WorldWideScience

Sample records for aqueous phase analytes

  1. Optical Detection of Aqueous Phase Analytes via Host-Guest Interactions on a Lipid Membrane Surface

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, D.Y.; Waggoner, T.A.

    1999-01-11

    The organization and assembly of molecules in cellular membranes is orchestrated through the recognition and binding of specific chemical signals. A simplified version of the cellular membrane system has been developed using a synthetically prepared membrane receptor incorporated into a biologically derived lipid bilayer. Through an interplay of electrostatic and van der Wards interactions, aggregation or dispersion of molecular components could be executed on command using a specific chemical signal. A pyrene fluorophore was used as an optical probe to monitor the aggregational state of the membrane receptors in the bilayer matrix. The pyrene excimer emission to monomer emission (E/M) intensity ratio gave a relative assessment of the local concentration of receptors in the membrane. Bilayers were prepared with receptors selective for the divalent metal ions of copper, mercury, and lead. Addition of the metal ions produced a rapid dispersion of aggregated receptor components at nano- to micro-molar concentrations. The process was reversible by sequestering the metal ions with EDTA. Receptors for proteins and polyhistidine were also prepared and incorporated into phosphatidylcholine lipid bilayers. In this case, the guest molecules bound to the membrane through multiple points of interaction causing aggregation of initially dispersed receptor molecules. The rapid, selective, and sensitive fluorescence optical response of these lipid assemblies make them attractive in sensor applications for aqueous phase metal ions and polypeptides.

  2. Analytical capabilities of laboratory, benchtop and handheld X-ray fluorescence systems for detection of metals in aqueous samples pre-concentrated with solid-phase extraction disks

    Energy Technology Data Exchange (ETDEWEB)

    Margui, E., E-mail: eva.margui@udg.edu [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Hidalgo, M. [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Queralt, I. [Laboratory of X-ray Analytical Applications, Institute of Earth Sciences ' Jaume Almera' , CSIC, Sole Sabaris s/n, 08028 Barcelona (Spain); Van Meel, K. [Department of Chemistry, University of Antwerp, Universiteitsplein 1, 2640 Antwerp (Belgium); Fontas, C. [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain)

    2012-01-15

    We aimed to achieve improved instrumental sensitivity and detection limits for the analysis of several elements (Cu, Ni, Zn, Pb and Cd) in aqueous samples with energy dispersive X-ray fluorescence spectrometry (EDXRF). The metals were pre-concentrated from aqueous solutions using commercially available organic-based solid-phase extraction (SPE) disks functionalized with iminodiacetate groups. These thin-layer organic materials provide an ideal support for XRF analysis. The elements were collected on the SPE extraction disks using a simple filtration procedure (starting with 1 L of aqueous sample) that allows direct XRF measurements to be performed in the field (in situ). We evaluated the analytical possibilities and drawbacks of using this pre-concentration procedure in combination with the following XRF configurations: a handheld unit, a benchtop EDXRF system and a high-energy polarized-beam EDXRF instrument (HE-P-EDXRF). Using the HE-P-EDXRF system, the detection limits for all metals were more than one order of magnitude lower than those attained using handheld and benchtop EDXRF instrumentation. For the detection of metal concentrations higher than {approx} 20 {mu}g/L, however, handheld or benchtop systems remain a very good option due to their extreme simplicity of operation and low-cost, compact design. We demonstrate the application of these methodologies, using the three equipment systems, to the analysis of trace concentrations of metals in different types of aqueous samples, including tap water and waste water. - Highlights: Black-Right-Pointing-Pointer Use of solid-phase extraction disks for pre-concentration of Cu, Ni, Zn, Pb and Cd. Black-Right-Pointing-Pointer Combination of this pre-concentration procedure with different XRF systems. Black-Right-Pointing-Pointer Successful application to trace metal determination in tap and waste water samples. Black-Right-Pointing-Pointer Direct measurements in the field are possible if a handheld unit is used.

  3. Analytical investigation of fluorescent complexes of leucine-8-hydroxyquinaldine and leucine-8-hydroxyquinoline in aqueous phase using spectroscopic techniques

    International Nuclear Information System (INIS)

    A new method has been developed by preparing complexes involving condensation of Leucine with 8-hydroxyquinaldine and 8-hydroxyquinoline separately. The products so obtained are being investigated for identification and quantitative estimation using different spectroscopic techniques including fluorescence activity of newly synthesized complexes. The method adopted in our laboratory is rapid, versatile, reproducible and provides excellent results for adoption by analytical, agriculture and biomedical laboratories to estimate amino acids and metals in composite matrix at economical costs. Identification of amino acids in nano mole quantities has become possible by fluorescence activity of leucine- 8-hydroxyquinaldine and leucine-8-hydroxyquinoline complexes involving different excitation and emission wavelengths. This fluorescence activity of the complexes is 100 to 1000 times higher than assay method involving ninhydrin and amino acid analyzer. (author)

  4. Aqueous-phase OH oxidation of glyoxal: application of a novel analytical approach employing aerosol mass spectrometry and complementary off-line techniques.

    Science.gov (United States)

    Lee, Alex K Y; Zhao, R; Gao, S S; Abbatt, J P D

    2011-09-29

    Aqueous-phase chemistry of glyoxal may play an important role in the formation of highly oxidized secondary organic aerosol (SOA) in the atmosphere. In this work, we use a novel design of photochemical reactor that allows for simultaneous photo-oxidation and atomization of a bulk solution to study the aqueous-phase OH oxidation of glyoxal. By employing both online aerosol mass spectrometry (AMS) and offline ion chromatography (IC) measurements, glyoxal and some major products including formic acid, glyoxylic acid, and oxalic acid in the reacting solution were simultaneously quantified. This is the first attempt to use AMS in kinetics studies of this type. The results illustrate the formation of highly oxidized products that likely coexist with traditional SOA materials, thus, potentially improving model predictions of organic aerosol mass loading and degree of oxidation. Formic acid is the major volatile species identified, but the atmospheric relevance of its formation chemistry needs to be further investigated. While successfully quantifying low molecular weight organic oxygenates and tentatively identifying a reaction product formed directly from glyoxal and hydrogen peroxide, comparison of the results to the offline total organic carbon (TOC) analysis clearly shows that the AMS is not able to quantitatively monitor all dissolved organics in the bulk solution. This is likely due to their high volatility or low stability in the evaporated solution droplets. This experimental approach simulates atmospheric aqueous phase processing by conducting oxidation in the bulk phase, followed by evaporation of water and volatile organics to form SOA. PMID:21854005

  5. Analytical applications of partitioning in aqueous two-phase systems: Exploring protein structural changes and protein-partner interactions in vitro and in vivo by solvent interaction analysis method.

    Science.gov (United States)

    Zaslavsky, Boris Y; Uversky, Vladimir N; Chait, Arnon

    2016-05-01

    This review covers the fundamentals of protein partitioning in aqueous two-phase systems (ATPS). Included is a review of advancements in the analytical application of solute partitioning in ATPS over the last two decades, with multiple examples of experimental data providing evidence that phase-forming polymers do not interact with solutes partitioned in ATPS. The partitioning of solutes is governed by the differences in solute interactions with aqueous media in the two phases. Solvent properties of the aqueous media in these two phases may be characterized and manipulated. The solvent interaction analysis (SIA) method, based on the solute partitioning in ATPS, may be used for characterization and analysis of individual proteins and their interactions with different partners. The current state of clinical proteomics regarding the discovery and monitoring of new protein biomarkers is discussed, and it is argued that the protein expression level in a biological fluid may be not the optimal focus of clinical proteomic research. Multiple examples of application of the SIA method for discovery of changes in protein structure and protein-partner interactions in biological fluids are described. The SIA method reveals new opportunities for discovery and monitoring structure-based protein biomarkers. PMID:26923390

  6. Aqueous phase processing of secondary organic aerosol from isoprene photooxidation

    Science.gov (United States)

    Liu, Y.; Monod, A.; Tritscher, T.; Praplan, A. P.; DeCarlo, P. F.; Temime-Roussel, B.; Quivet, E.; Marchand, N.; Dommen, J.; Baltensperger, U.

    2012-07-01

    Transport of reactive air masses into humid and wet areas is highly frequent in the atmosphere, making the study of aqueous phase processing of secondary organic aerosol (SOA) very relevant. We have investigated the aqueous phase processing of SOA generated from gas-phase photooxidation of isoprene using a smog chamber. The SOA collected on filters was extracted by water and subsequently oxidized in the aqueous phase either by H2O2 under dark conditions or by OH radicals in the presence of light, using a photochemical reactor. Online and offline analytical techniques including SMPS, HR-AMS, H-TDMA, TD-API-AMS, were employed for physical and chemical characterization of the chamber SOA and nebulized filter extracts. After aqueous phase processing, the particles were significantly more hygroscopic, and HR-AMS data showed higher signal intensity at m/z 44 and a lower signal intensity at m/z 43, thus showing the impact of aqueous phase processing on SOA aging, in good agreement with a few previous studies. Additional offline measurement techniques (IC-MS, APCI-MS2 and HPLC-APCI-MS) permitted the identification and quantification of sixteen individual chemical compounds before and after aqueous phase processing. Among these compounds, small organic acids (including formic, glyoxylic, glycolic, butyric, oxalic and 2,3-dihydroxymethacrylic acid (i.e. 2-methylglyceric acid)) were detected, and their concentrations significantly increased after aqueous phase processing. In particular, the aqueous phase formation of 2-methylglyceric acid and trihydroxy-3-methylbutanal was correlated with the consumption of 2,3-dihydroxy-2-methyl-propanal, and 2-methylbutane-1,2,3,4-tetrol, respectively, and an aqueous phase mechanism was proposed accordingly. Overall, the aging effect observed here was rather small compared to previous studies, and this limited effect could possibly be explained by the lower liquid phase OH concentrations employed here, and/or the development of oligomers

  7. Aqueous phase processing of secondary organic aerosol from isoprene photooxidation

    Directory of Open Access Journals (Sweden)

    Y. Liu

    2012-07-01

    Full Text Available Transport of reactive air masses into humid and wet areas is highly frequent in the atmosphere, making the study of aqueous phase processing of secondary organic aerosol (SOA very relevant. We have investigated the aqueous phase processing of SOA generated from gas-phase photooxidation of isoprene using a smog chamber. The SOA collected on filters was extracted by water and subsequently oxidized in the aqueous phase either by H2O2 under dark conditions or by OH radicals in the presence of light, using a photochemical reactor. Online and offline analytical techniques including SMPS, HR-AMS, H-TDMA, TD-API-AMS, were employed for physical and chemical characterization of the chamber SOA and nebulized filter extracts. After aqueous phase processing, the particles were significantly more hygroscopic, and HR-AMS data showed higher signal intensity at m/z 44 and a lower signal intensity at m/z 43, thus showing the impact of aqueous phase processing on SOA aging, in good agreement with a few previous studies. Additional offline measurement techniques (IC-MS, APCI-MS2 and HPLC-APCI-MS permitted the identification and quantification of sixteen individual chemical compounds before and after aqueous phase processing. Among these compounds, small organic acids (including formic, glyoxylic, glycolic, butyric, oxalic and 2,3-dihydroxymethacrylic acid (i.e. 2-methylglyceric acid were detected, and their concentrations significantly increased after aqueous phase processing. In particular, the aqueous phase formation of 2-methylglyceric acid and trihydroxy-3-methylbutanal was correlated with the consumption of 2,3-dihydroxy-2-methyl-propanal, and 2-methylbutane-1,2,3,4-tetrol, respectively, and an aqueous phase mechanism was proposed accordingly. Overall, the aging effect observed here was rather small compared to previous studies, and this limited effect could possibly be explained by the lower liquid phase OH

  8. Spectroelectrochemical Sensing of Aqueous Iron: An Experiment for Analytical Chemistry

    Science.gov (United States)

    Shtoyko, Tanya; Stuart, Dean; Gray, H. Neil

    2007-01-01

    We have designed a laboratory experiment to illustrate the use of spectroelectrochemical techniques for determination of aqueous iron. The experiment described in this article is applicable to an undergraduate laboratory course in analytical chemistry. Students are asked to fabricate spectroelectrochemical sensors, make electrochemical and optical…

  9. Modeling Non-aqueous Phase Liquid Displacement Process

    Institute of Scientific and Technical Information of China (English)

    Yang Zhenqing; Shao Changjin; Zhou Guanggang; Qiu Chao

    2007-01-01

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

  10. A New Efficient Analytical Method for Picolinate Ion Measurements in Complex Aqueous Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Parazols, M.; Dodi, A. [CEA Cadarache, Lab Anal Radiochim and Chim, DEN, F-13108 St Paul Les Durance (France)

    2010-07-01

    This study focuses on the development of a new simple but sensitive, fast and quantitative liquid chromatography method for picolinate ion measurement in high ionic strength aqueous solutions. It involves cation separation over a chromatographic CS16 column using methane sulfonic acid as a mobile phase and detection by UV absorbance (254 nm). The CS16 column is a high-capacity stationary phase exhibiting both cation exchange and RP properties. It allows interaction with picolinate ions which are in their zwitterionic form at the pH of the mobile phase (1.3-1.7). Analysis is performed in 30 min with a detection limit of about 0.05 {mu}M and a quantification limit of about 0.15 {mu}M. Moreover, this analytical technique has been tested efficiently on complex aqueous samples from an effluent treatment facility. (authors)

  11. Aqueous phase chemical properties of transactinides

    International Nuclear Information System (INIS)

    65-s 261Rf and 34-s 262Ha have been produced at the Lawrence Berkeley Laboratory 88-Inch Cyclotron by the 248Cm(18O,5n) and 249Bk(18O,5n) reactions, respectively. These isotopes of element 104 and 105 are produced at a one atom per minute rate, and rapid chemical separations are performed on a one-minute time scale. They are identified by detecting the α- and SF radiations from their decay. First aqueous phase chemical separations of Rf and Ha determined their primary oxidation states in aqueous solution, placing them in the periodic table at the bottom of groups 4 and 5, respectively, and confirming Seaborg's actinide concept. More recently, experiments measuring the chemical properties in more detail have uncovered some interesting and unexpected trends in periodic table properties

  12. Oxidation of Glyoxal in the Aqueous Phase

    Science.gov (United States)

    Schaefer, Thomas; Herrmann, Hartmut

    2014-05-01

    Large amounts of volatile organic compounds (VOCs) are emitted into the atmosphere from biogenic and anthropogenic sources. The emitted VOCs can be further oxidized in the gas phase as well as in the aqueous phase (cloud droplets, fog, rain and deliquescent particles) to form semivolatile carbonyl compounds. For example, the carbonyl compound glyoxal can be produced by the oxidation process of isoprene. Additionally, these semivolatile carbonyl compounds might be important for the formation of secondary organic aerosol (SOA) by partitioning between gas- and liquid phase of pre-existing particles. In the gas phase as well as in the aqueous phase (cloud droplets, fog, rain and deliquescent particles) these compounds can be further oxidized, e.g., by radicals (OH and NO3) leading to peroxy radicals and then to substituted organics. Two concepts exist in the literature to describe the glyoxal oxidation pathway via alkyl radicals to the peroxy radicals by the addition of molecular oxygen. The first one[1] states that peroxy radical formation occurs with a rate constant of k = 1 × 109 M-1 s-1. The second concept[2] assumes that this is a minor reaction pathway because of the lower rate constant of k = 1 × 106 M-1 s-1. The difference in the rate constants of the oxygen addition is of about three orders of magnitude which might lead to different oxidation products and yields in aqueous solution. In the present work, the formation and the decay of the formed glyoxyl radicals and glyoxyl peroxy radicals were studied in low and high concentrated oxygen solutions using a laser photolysis long path absorption setup (LP-LPA). To clarify the difference a method introduced by Adams et al., 1969[3] to measure the rate constant of the oxygen addition on alkyl radical was modified for laser flash photolysis conditions and successfully applied. In this study a rate constant for the addition reaction of molecular oxygen of k = 8 × 108 M-1 s-1 was measured. This clearly indicates

  13. Quick analytical method for the determination of iodide and iodate ions in aqueous solutions

    International Nuclear Information System (INIS)

    An analytical quick-test method was developed to determine iodide and iodate ions in aqueous solutions using solid phase extraction cartridges for sample preparation. Work was focussed on finding simple, but efficient conditions for quantitative separation of iodate and iodide. Iodine amounts were then determined by standard methods. Ion-exchange absorbers in cartridge form were used. Selectivity and yield of the species separation were studied at pH value of 5-10 and various solution compositions using 131I radioactive tracer. The electrolytes used were diluted alkaline, nitrate and boric acid-borate solutions. Application to nuclear reactor cooling water analysis or environmental investigations and monitoring is proposed. (author)

  14. Tunable aqueous polymer-phase impregnated resins-technology-a novel approach to aqueous two-phase extraction.

    Science.gov (United States)

    van Winssen, F A; Merz, J; Schembecker, G

    2014-02-14

    Aqueous Two-Phase Extraction (ATPE) represents a promising unit operation for downstream processing of biotechnological products. The technique provides several advantages such as a biocompatible environment for the extraction of sensitive and biologically active compounds. However, the tendency of some aqueous two-phase systems to form intensive and stable emulsions can lead to long phase separation times causing an increased footprint for the required mixer-settler devices or the need for additional equipment such as centrifuges. In this work, a novel approach to improve ATPE for downstream processing applications called 'Tunable Aqueous Polymer-Phase Impregnated Resins' (TAPPIR(®))-Technology is presented. The technology is based on the immobilization of one aqueous phase inside the pores of a solid support. The second aqueous phase forms the bulk liquid around the impregnated solids. Due to the immobilization of one phase, phase emulsification and phase separation of ATPE are realized in a single step. In this study, a biodegradable and sustainable aqueous two-phase system consisting of aqueous polyethylene glycol/sodiumcitrate solutions was chosen. The impregnation of different macroporous glass and ceramic solids was investigated and could be proven to be stable. Additionally, the separation of the dye Patent blue V was successfully performed with the TAPPIR(®)-Technology. Thus, the "proof of principle" of this technology is presented. PMID:24462465

  15. Application of an analytical phase transformation model

    Institute of Scientific and Technical Information of China (English)

    LIU Feng; WANG Hai-feng; YANG Chang-lin; CHEN Zheng; YANG Wei; YANG Gen-cang

    2006-01-01

    Employing isothermal and isochronal differential scanning calorimetry, an analytical phase transformation model was used to study the kinetics of crystallization of amorphous Mg82.3Cu17.7 and Pd40Cu30P20Ni10 alloys. The analytical model comprised different combinations of various nucleation and growth mechanisms for a single transformation. Applying different combinations of nucleation and growth mechanisms, the nucleation and growth modes and the corresponding kinetic and thermodynamic parameters, have been determined. The influence of isothermal pre-annealing on subsequent isochronal crystallization kinetics with the increase of pre-annealing can be analyzed. The results show that the changes of the growth exponent, n, and the effective overall activation energy Q, occurring as function of the degree of transformation, do not necessarily imply a change of nucleation and growth mechanisms, i.e. such changes can occur while the transformation is isokinetic.

  16. Advanced Aqueous Phase Catalyst Development using Combinatorial Methods Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The use of combinatorial methods is proposed to rapidly screen catalyst formulations for the advanced development of aqueous phase oxidation catalysts with greater...

  17. Electrostatic interactions and aqueous two-phase separation modes of aqueous mixed oppositely charged surfactants system.

    Science.gov (United States)

    Hao, Li-Sheng; Gui, Yuan-Xiang; Chen, Yan-Mei; He, Shao-Qing; Nan, Yan-Qing; You, Yi-Lan

    2012-08-30

    Electrostatic interactions play an important role in setting the aqueous two-phase separation behaviors of mixtures of oppositely charged surfactants. The aqueous mixture of cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfonate (AS) is actually a five-component system, comprised of CTAB, AS, complex salt (cetyltrimethylammonium dodecylsulfonate, abbreviated as CTA(+)AS(-)), NaBr, and water. In the three-dimensional pyramid phase diagram, the aqueous two-phase region with excess AS or with excess CTAB extends successively from the region very near to the NaBr-H2O line through the CTAB-AS-H2O conventional mixing plane to the CTA(+)AS(-)-AS-H2O side plane or to the CTA(+)AS(-)-CTAB-H2O side plane, respectively. Large or small molar ratios between the counterions and their corresponding surfactant ions for oppositely charged surfactants located in the NaBr side or the CTA(+)AS(-) side of the pyramid imply strong or weak electrostatic screening. Electrostatic screening of counterions alters the electrostatic attractions between the oppositely charged head groups or the electrostatic repulsions between the like-charged head groups in excess, and the electrostatic free energy of aggregation thus affects the aqueous two-phase separation modes. Composition analysis, rheological property investigation, and TEM images suggest that there are two kinds of aqueous two-phase systems (ATPSs). On the basis of these experimental results and Kaler's cell model, two kinds of phase separation modes were proposed. Experimental results also indicate that all of the top phases are surfactant-rich, and all of the bottom phases are surfactant-poor; the density difference between the top phase and the bottom phase in one ATPS is very small; the interfacial tension (σ) of the ATPS is ultralow. PMID:22856887

  18. Analytical method of elements in humic acid phase

    International Nuclear Information System (INIS)

    A method of rapid extraction of humic acid, determination of carbon in the humic acid and a phase analytical method of major relevant elements such as uranium, gold etc, in the humic acid phase are described. Good results are achieved in exploration of hidden uranium ores by using this phase analytical technique

  19. Charged hydrophobic colloids at an oil-aqueous phase interface

    Science.gov (United States)

    Kelleher, Colm P.; Wang, Anna; Guerrero-García, Guillermo Iván; Hollingsworth, Andrew D.; Guerra, Rodrigo E.; Krishnatreya, Bhaskar Jyoti; Grier, David G.; Manoharan, Vinothan N.; Chaikin, Paul M.

    2015-12-01

    Hydrophobic poly(methyl methacrylate) (PMMA) colloidal particles, when dispersed in oil with a relatively high dielectric constant, can become highly charged. In the presence of an interface with a conducting aqueous phase, image-charge effects lead to strong binding of colloidal particles to the interface, even though the particles are wetted very little by the aqueous phase. We study both the behavior of individual colloidal particles as they approach the interface and the interactions between particles that are already interfacially bound. We demonstrate that using particles which are minimally wetted by the aqueous phase allows us to isolate and study those interactions which are due solely to charging of the particle surface in oil. Finally, we show that these interactions can be understood by a simple image-charge model in which the particle charge q is the sole fitting parameter.

  20. Phase behaviour of tertiary recovery sulfonates - petroleum fractions - aqueous systems

    Energy Technology Data Exchange (ETDEWEB)

    Ghoniem, S.A.; Darwish, T.A.; Salamah, A.O.

    1988-02-01

    The phase behaviour of tertiary recovery sulfonates having commercial names TRS-10, TRS-16 and TRS-40 with aqueous phase and light petroleum fractions (non polar kerosene and gasoline) was studied at 20, 40 and 60/sup 0/C. The adopted pseudo components of the ternary diagram are hydrocarbon, surfactant and aqueous phase. The aqueous phase was composed of bidistilled water in addition to different proportions of pure alcohols and sodium chloride. The tested alcohols included methanol, ethanol, iso-propanol, n-butanol and n-pentanol. Thus, the best alcohol type and concentration in addition to optimum salinity, which correspond to maximum single phase region, were established for each surfactant at the various tested temperatures. It was shown that higher the affinity of the tested surfactant for hydrocarbon phase, the greater is the solubility of the corresponding optimum co-surfactant in water. The variation of optimum alcohol concentration with temperature, the effect of salt on the single phase region and the effect of hydrocarbon phase on the observed phenomena were discussed and found to agree with the previously established theories.

  1. Preparation of cationic polyacrylamide by aqueous two-phase polymerization

    Directory of Open Access Journals (Sweden)

    2010-05-01

    Full Text Available Cationic polyacrylamide (CPAM was synthesized by aqueous two-phase polymerization technique using acrylamide (AM and dimethylaminoethyl methacrylate methyl chloride (DMC as raw materials, aqueous polyethylene glycol 20000 (PEG 20000 solution as dispersant, 2,2′-azobis(2-amidinopropane dihydrochloride (V-50 as initiator and poly(dimethylaminoethyl methacrylate methyl chloride (PDMC as stabilizer. The polymer was characterized by infrared (IR spectroscopy, 1H-NMR spectrum and transmission electron microscopy (TEM. The copolymer composition was analyzed. The effect of monomers concentration, PEG 20000 concentration and stabilizer concentration on copolymer were investigated, respectively. The optimum reaction conditions for obtaining a stable CPAM aqueous two-phase system were monomers concentration 8~15%, PEG 20000 concentration 15~25%, and PDMC concentration 0.5~1.5%. Finally, the formation process of copolymer particles was investigated by optical microscope.

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

    International Nuclear Information System (INIS)

    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 H3PO4 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 μg L-1, repeatability of the extraction (R.S.D. -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

  3. Effect of salt identity on the phase diagram for a globularprotein in aqueous electrolyte solution

    Energy Technology Data Exchange (ETDEWEB)

    Bostrom, Mathias; Tavares, Frederico W.; Ninham, Barry W.; Prausnitz, John M.

    2006-02-22

    Monte Carlo simulations are used to establish the potential of mean force between two globular proteins in an aqueous electrolyte solution. This potential includes nonelectrostatic contributions arising from dispersion forces first, between the globular proteins, and second, between ions in solution and between each ion and the globular protein. These latter contributions are missing from standard models. The potential of mean force, obtained from simulation, is fitted to an analytic equation. Using our analytic potential of mean force and Barker-Henderson perturbation theory, we obtain phase diagrams for lysozyme solutions that include stable and metastable fluid-fluid and solid-fluid phases when the electrolyte is 0.2 M NaSCN or NaI or NaCl. The nature of the electrolyte has a significant effect on the phase diagram.

  4. Partitioning of glycomacropeptide in aqueous two-phase systems

    OpenAIRE

    Silva, C. A. S.; Coimbra, Jane Sélia dos Reis; Rojas, Edwin Elard Garcia; Teixeira, J. A.

    2009-01-01

    The partition behavior of glycomacropeptide (GMP) was determined in polyethylene glycol (PEG) and sodium citrate aqueous two-phase systems (ATPS). It was found that the partitioning of GMP depends on PEG molar mass, tie line length, pH, NaCl concentration and temperature. The obtained data indicates that GMP is preferentially partitioned into the PEG phase without addition of NaCl at pH 8.0. Larger tie line lengths and higher temperatures favor GMP partition to the PEG phase. Furt...

  5. Optimization of reversed-phase chromatography methods for peptide analytics.

    Science.gov (United States)

    Khalaf, Rushd; Baur, Daniel; Pfister, David

    2015-12-18

    The analytical description and quantification of peptide solutions is an essential part in the quality control of peptide production processes and in peptide mapping techniques. Traditionally, an important tool is analytical reversed phase liquid chromatography. In this work, we develop a model-based tool to find optimal analytical conditions in a clear, efficient and robust manner. The model, based on the Van't Hoff equation, the linear solvent strength correlation, and an analytical solution of the mass balance on a chromatographic column describing peptide retention in gradient conditions is used to optimize the analytical scale separation between components in a peptide mixture. The proposed tool is then applied in the design of analytical reversed phase liquid chromatography methods of five different peptide mixtures. PMID:26620597

  6. The role of nuclear analytical techniques in the study of aqueous corrosion of glasses

    International Nuclear Information System (INIS)

    Direct observation of resonant nuclear reactions, backscattering spectrometry and X ray microanalysis with a nuclear microprobe were used to determine elementary depth profiles in the near surface region of leached glasses. Some computing programs required to interpretate the analytical information detected were built. Experimental conditions to characterize glass samples without secondary effects were defined; and the influence of some leaching parameters was studied to describe the first stages of aqueous corrosion of borosilicate glasses

  7. New concept of analytical method for two-phase flow

    International Nuclear Information System (INIS)

    The authors are developing a new analytical method for vertical upward two-phase flow based on a concept that two-phase flow with minimum pressure energy consumption rate is the most stable and easily flowable two-phase flow for the given boundary conditions and, thus, such two-phase flow should be realized actually. Although this concept is applied basically one-dimensionally in the analytical method, gravity convection effect due to density difference between liquid film on the channel wall and two-phase flow core in the central region of the channel is taken into account through a two-dimensional turbulent flow analysis. An air-water two-phase flow experiment was performed to verify the proposed analytical method. In the present paper, results of the experimental analysis with the proposed method are reported. (author)

  8. Liquid crystalline phases in concentrated aqueous solutions of Na+ DNA.

    OpenAIRE

    Rill, R L

    1986-01-01

    Concentrated aqueous saline solutions of short (146-base-pair) DNA fragments suddenly become turbid and iridescent when the DNA concentration is slightly increased or the temperature is decreased. Microscopic examination through crossed polarizing filters shows that turbidity and iridescence is due to formation of a liquid crystalline DNA phase similar to cholesteric liquid crystals formed by other semirigid, but nonelectrolyte, chiral polymers. Several distinct textures of the liquid crystal...

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

    OpenAIRE

    Kneafsey, Timothy J.; HUNT, JAMES R.

    2004-01-01

    Many non-aqueous phase liquids (NAPLs) are expected to spread at the air – water interface, particularly under non-equilibrium conditions. In the vadose zone, this spreading should increase the surface area for mass transfer and the efficiency of volatile NAPL recovery by soil vapor extraction (SVE). Observations of spreading on water wet surfaces led to a conceptual model of oil spreading vertically above a NAPL pool in the vadose zone. Analysis of this model predicts that spreading can enha...

  10. Road Transportable Analytical Laboratory system. Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    Finger, S.M.; Keith, V.F.; Spertzel, R.O.; De Avila, J.C.; O`Donnell, M.; Vann, R.L.

    1993-09-01

    This developmental effort clearly shows that a Road Transportable Analytical Laboratory System is a worthwhile and achievable goal. The RTAL is designed to fully analyze (radioanalytes, and organic and inorganic chemical analytes) 20 samples per day at the highest levels of quality assurance and quality control. It dramatically reduces the turnaround time for environmental sample analysis from 45 days (at a central commercial laboratory) to 1 day. At the same time each RTAL system will save the DOE over $12 million per year in sample analysis costs compared to the costs at a central commercial laboratory. If RTAL systems were used at the eight largest DOE facilities (at Hanford, Savannah River, Fernald, Oak Ridge, Idaho, Rocky Flats, Los Alamos, and the Nevada Test Site), the annual savings would be $96,589,000. The DOE`s internal study of sample analysis needs projects 130,000 environmental samples requiring analysis in FY 1994, clearly supporting the need for the RTAL system. The cost and time savings achievable with the RTAL system will accelerate and improve the efficiency of cleanup and remediation operations throughout the DOE complex.

  11. Simultaneous Separation of Manganese, Cobalt, and Nickel by the Organic-Aqueous-Aqueous Three-Phase Solvent Extraction

    Science.gov (United States)

    Shirayama, Sakae; Uda, Tetsuya

    2016-04-01

    This research outlines an organic-aqueous-aqueous three-phase solvent extraction method and proposes its use in a new metal separation process for the recycling of manganese (Mn), cobalt (Co), and nickel (Ni) from used lithium ion batteries (LIBs). The three-phase system was formed by mixing xylene organic solution, 50 pct polyethylene glycol (PEG) aqueous solution, and 1 mol L-1 sodium sulfate (Na2SO4) aqueous solution. The xylene organic solution contained 2-ethylhexylphosphonic acid (D2EHPA) as an extractant for Mn ion, and the Na2SO4 aqueous solution contained 1 mol L-1 potassium thiocyanate (KSCN) as an extractant for Co ion. Concentrations of the metal ions were varied by dissolving metal sulfates in the Na2SO4 aqueous solution. As a result of the experiments, Mn, Co, and Ni ions were distributed in the xylene organic phase, PEG-rich aqueous phase, and Na2SO4-rich aqueous phase, respectively. The separation was effective when the pH value was around 4. Numerical simulation was also conducted in order to predict the distribution of metal ions after the multi-stage counter-current extractions.

  12. An analytical formulation for phase noise in MEMS oscillators.

    Science.gov (United States)

    Agrawal, Deepak; Seshia, Ashwin

    2014-12-01

    In recent years, there has been much interest in the design of low-noise MEMS oscillators. This paper presents a new analytical formulation for noise in a MEMS oscillator encompassing essential resonator and amplifier nonlinearities. The analytical expression for oscillator noise is derived by solving a second-order nonlinear stochastic differential equation. This approach is applied to noise modeling of an electrostatically addressed MEMS resonator-based square-wave oscillator in which the resonator and oscillator circuit nonlinearities are integrated into a single modeling framework. By considering the resulting amplitude and phase relations, we derive additional noise terms resulting from resonator nonlinearities. The phase diffusion of an oscillator is studied and the phase diffusion coefficient is proposed as a metric for noise optimization. The proposed nonlinear phase noise model provides analytical insight into the underlying physics and a pathway toward the design optimization for low-noise MEMS oscillators. PMID:25474770

  13. Adsorption of Carboxylic Acids on Reservoir Minerals from Organic and Aqueous Phase

    DEFF Research Database (Denmark)

    Madsen, Lene; Lind, Ida

    1998-01-01

    Adsorption of organic acids onto North Sea chalk and pure minerals from a hydrocarbon phase and an aqueous phase show that the maximum adsorption is larger for calcite than for silicate surfaces in the hydrocarbon phase. The opposite is observed, however, in the aqueous phase. This suggests that...

  14. Isotropic-nematic phase transition in aqueous sepiolite suspensions.

    Science.gov (United States)

    Woolston, Phillip; van Duijneveldt, Jeroen S

    2015-01-01

    Aqueous suspensions of sepiolite clay rods in water tend to form gels on increase of concentration. Here it is shown how addition of a small amount (0.1% of the clay mass) of a common stabiliser for clay suspensions, sodium polyacrylate, can allow the observation of an isotropic-nematic liquid crystal phase transition. This transition was found to move to higher clay concentrations upon adding NaCl, with samples containing 10(-3) M salt or above only displaying a gel phase. Even samples that initially formed liquid crystals had a tendency to form gels after several weeks, possibly due to Mg(2+) ions leaching from the clay mineral. PMID:25313468

  15. Kinetics of the electropolymerization of aminoanthraquinone from aqueous solutions and analytical applications of the polymer film

    Directory of Open Access Journals (Sweden)

    Shymaa S. Medany

    2012-07-01

    Full Text Available Poly 1-amino-9, 10-anthraquinone (PAAQ films were prepared by the electropolymerization of 1-amino-9,10-anthraquinone (AAQ on platinum substrate from aqueous media, where 5.0 × 10−3 mol L−1 AAQ and 6.0 mol L−1 H2SO4 were used. The kinetics of the electropolymerization process was investigated by determining the change of the charge consumed during the polymerization process with time at different concentrations of both monomer and electrolyte. The results have shown that the process follows first order kinetics with respect to the monomer concentration. The order of the reaction with respect to the aqueous solvent i.e. H2SO4 was found to be negative. The polymer films were successfully used as sensors for the electroanalytical determination of many hazardous compounds, e.g. phenols, and biologically important materials like dopamine. The electroanalytical determination was based on the measurements of the oxidation current peak of the material in the cyclic voltammetric measurements. The cyclic voltammograms were recorded at a scan rate of 100 mV s−1 and different analyte concentrations. A calibration curve was constructed for each analyte, from which the determination of low concentrations of catechol and hydroquinone (HQ as examples of hazardous compounds present in waste water and also for ascorbic acid and dopamine as examples of valuable biological materials can be achieved.

  16. Determination of protein loss during aqueous and phase partition fixation using formalin and glutaraldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Mays, E.T.; Feldhoff, R.C.; Nettleton, G.S.

    1984-10-01

    In phase partition fixation tissue is immersed in an organic solvent at equilibrium with an aqueous phase containing a fixing agent. By using radioisotope labeling techniques the effects of phase partition fixation on protein retention during fixation of tissue with formalin and glutaraldehyde have been determined and compared with those of standard aqueous fixation using these fixatives. It has been shown that retention of protein in tissue during phase partition fixation was as good or better than during aqueous fixation. Improved retention provides further evidence that phase partition fixation may be a useful alternative to aqueous fixation.

  17. Bioligand-mediated partitioning of radionuclides to the aqueous phase

    International Nuclear Information System (INIS)

    The aqueous-phase partitioning of 59Fe, 147Pm, 234Th and 241Am by complexing compounds from subsurface bacteria has previously been studied in the presence of quartz sand. In this study the aqueous-phase partitioning of pico- to submicromolar amounts of 59Fe, 147Pm, 234Th and 241Am was analyzed in the presence of TiO2 and exudates from three species of subsurface bacteria: Pseudomonas fluorescens, Pseudomonas stutzeri, and Shewanella putrefaciens. All were grown under aerobic conditions and P. stutzeri and S. putrefaciens were grown under anaerobic conditions as well. The supernatants of the aerobic and anaerobic cultures were collected and radionuclide was added. TiO2, with BET surface area of 49.9 m2 x g-1, was added to the supernatant radionuclide mix, and the pH was adjusted to approximately 8. After incubation, the amount of radionuclide in the liquid phase of the samples and controls was analyzed using scintillation method. Two types of values were calculated: solution% = the activity maintained in solution relative to the total activity, and Q-values = the quotient between the activity in samples and the activity in controls. Aerobic supernatants had solution% values between 89% and 100% for 59Fe and between 18 and 43% for 234Th. The solution% values for 241Am and 147Pm were less than 2% overall, but the Q-values were between 34 and 115 times more 241Am in bacterial supernatants than in controls. The corresponding values for 147Pm ranged from 6 to 20 times more than in the control. The solution% values for all elements in the presence of anaerobic supernatants were below 2%, but the Q-values clustered around 7 for 59Fe and ranging from 2 to 29 for 234Th, indicated that anaerobic supernatants partitioned these elements to the aqueous phase. Both aerobic and anaerobic supernatants tested positive for complexing compounds when analyzed, using the Chrome Azurol S assay. Complexation with excreted organic ligands is most likely the reason for the higher amounts

  18. Analytical Approach to Grid Operation With Phase Shifting Transformers

    NARCIS (Netherlands)

    Verboomen, J.; Van Hertem, D.; Schavemaker, P.H.; King, W.L.; Belmans, R.

    2008-01-01

    Analytical expressions are derived to gain insight in the operating principles of phase shifting transformers (PSTs) in a highly meshed grid. To this extent, the dc load flow algorithm is adapted to account for such devices. This leads to a linear expression for the relation between PST settings and

  19. Dissolved plume attenuation with DNAPL source remediation, aqueous decay and volatilization — Analytical solution, model calibration and prediction uncertainty

    Science.gov (United States)

    Parker, Jack C.; Park, Eungyu; Tang, Guoping

    2008-11-01

    A vertically-integrated analytical model for dissolved phase transport is described that considers a time-dependent DNAPL source based on the upscaled dissolution kinetics model of Parker and Park with extensions to consider time-dependent source zone biodecay, partial source mass reduction, and remediation-enhanced source dissolution kinetics. The model also considers spatial variability in aqueous plume decay, which is treated as the sum of aqueous biodecay and volatilization due to diffusive transport and barometric pumping through the unsaturated zone. The model is implemented in Excel/VBA coupled with (1) an inverse solution that utilizes prior information on model parameters and their uncertainty to condition the solution, and (2) an error analysis module that computes parameter covariances and total prediction uncertainty due to regression error and parameter uncertainty. A hypothetical case study is presented to evaluate the feasibility of calibrating the model from limited noisy field data. The results indicate that prediction uncertainty increases significantly over time following calibration, primarily due to propagation of parameter uncertainty. However, differences between the predicted performance of source zone partial mass reduction and the known true performance were reasonably small. Furthermore, a clear difference is observed between the predicted performance for the remedial action scenario versus that for a no-action scenario, which is consistent with the true system behavior. The results suggest that the model formulation can be effectively utilized to assess monitored natural attenuation and source remediation options if careful attention is given to model calibration and prediction uncertainty issues.

  20. Dissolved plume attenuation with DNAPL source remediation, aqueous decay and volatilization--analytical solution, model calibration and prediction uncertainty.

    Science.gov (United States)

    Parker, Jack C; Park, Eungyu; Tang, Guoping

    2008-11-14

    A vertically-integrated analytical model for dissolved phase transport is described that considers a time-dependent DNAPL source based on the upscaled dissolution kinetics model of Parker and Park with extensions to consider time-dependent source zone biodecay, partial source mass reduction, and remediation-enhanced source dissolution kinetics. The model also considers spatial variability in aqueous plume decay, which is treated as the sum of aqueous biodecay and volatilization due to diffusive transport and barometric pumping through the unsaturated zone. The model is implemented in Excel/VBA coupled with (1) an inverse solution that utilizes prior information on model parameters and their uncertainty to condition the solution, and (2) an error analysis module that computes parameter covariances and total prediction uncertainty due to regression error and parameter uncertainty. A hypothetical case study is presented to evaluate the feasibility of calibrating the model from limited noisy field data. The results indicate that prediction uncertainty increases significantly over time following calibration, primarily due to propagation of parameter uncertainty. However, differences between the predicted performance of source zone partial mass reduction and the known true performance were reasonably small. Furthermore, a clear difference is observed between the predicted performance for the remedial action scenario versus that for a no-action scenario, which is consistent with the true system behavior. The results suggest that the model formulation can be effectively utilized to assess monitored natural attenuation and source remediation options if careful attention is given to model calibration and prediction uncertainty issues. PMID:18502537

  1. Aqueous two-phase system based on natural quaternary ammonium compounds for the extraction of proteins.

    Science.gov (United States)

    Zeng, Chao-Xi; Xin, Rui-Pu; Qi, Sui-Jian; Yang, Bo; Wang, Yong-Hua

    2016-02-01

    Aqueous two-phase systems, based on the use of natural quaternary ammonium compounds, were developed to establish a benign biotechnological route for efficient protein separation. In this study, aqueous two-phase systems of two natural resources betaine and choline with polyethyleneglycol (PEG400/600) or inorganic salts (K2 HPO4 /K3 PO4 ) were formed. It was shown that in the K2 HPO4 -containing aqueous two-phase system, hydrophobic interactions were an important driving force of protein partitioning, while protein size played a vital role in aqueous two-phase systems that contained polyethylene glycol. An extraction efficiency of more than 90% for bovine serum albumin in the betaine/K2 HPO4 aqueous two-phase system can be obtained, and this betaine-based aqueous two-phase system provided a gentle and stable environment for the protein. In addition, after investigation of the cluster phenomenon in the betaine/K2 HPO4 aqueous two-phase systems, it was suggested that this phenomenon also played a significant role for protein extraction in this system. The development of aqueous two-phase systems based on natural quaternary ammonium compounds not only provided an effective and greener method of aqueous two-phase system to meet the requirements of green chemistry but also may help to solve the mystery of the compartmentalization of biomolecules in cells. PMID:26447826

  2. Analytical techniques for characterization of cyclodextrin complexes in aqueous solution: a review.

    Science.gov (United States)

    Mura, Paola

    2014-12-01

    Cyclodextrins are cyclic oligosaccharides endowed with a hydrophilic outer surface and a hydrophobic inner cavity, able to form inclusion complexes with a wide variety of guest molecules, positively affecting their physicochemical properties. In particular, in the pharmaceutical field, cyclodextrin complexation is mainly used to increase the aqueous solubility and dissolution rate of poorly soluble drugs, and to enhance their bioavailability and stability. Analytical characterization of host-guest interactions is of fundamental importance for fully exploiting the potential benefits of complexation, helping in selection of the most appropriate cyclodextrin. The assessment of the actual formation of a drug-cyclodextrin inclusion complex and its full characterization is not a simple task and often requires the use of different analytical methods, whose results have to be combined and examined together. The purpose of the present review is to give, as much as possible, a general overview of the main analytical tools which can be employed for the characterization of drug-cyclodextrin inclusion complexes in solution, with emphasis on their respective potential merits, disadvantages and limits. Further, the applicability of each examined technique is illustrated and discussed by specific examples from literature. PMID:24680374

  3. Condensed Phase Membrane Introduction Mass Spectrometry with Direct Electron Ionization: On-line Measurement of PAHs in Complex Aqueous Samples

    Science.gov (United States)

    Termopoli, Veronica; Famiglini, Giorgio; Palma, Pierangela; Cappiello, Achille; Vandergrift, Gregory W.; Krogh, Erik T.; Gill, Chris G.

    2016-02-01

    Polycyclic aromatic hydrocarbons (PAHs) are USEPA regulated priority pollutants. Their low aqueous solubility requires very sensitive analytical methods for their detection, typically involving preconcentration steps. Presented is the first demonstrated `proof of concept' use of condensed phase membrane introduction mass spectrometry (CP-MIMS) coupled with direct liquid electron ionization (DEI) for the direct, on-line measurement of PAHs in aqueous samples. DEI is very well suited for the ionization of PAHs and other nonpolar compounds, and is not significantly influenced by the co-elution of matrix components. Linear calibration data for low ppb levels of aqueous naphthalene, anthracene, and pyrene is demonstrated, with measured detection limits of 4 ppb. Analytical response times (t10%-90% signal rise) ranged from 2.8 min for naphthalene to 4.7 min for pyrene. Both intra- and interday reproducibility has been assessed (waters, sea waters, and a hydrocarbon extraction production waste water sample. For these spiked, complex samples, direct PAH measurement by CP-MIMS-DEI yielded minimal signal suppression from sample matrix effects (81%-104%). We demonstrate the use of this analytical approach to directly monitor real-time changes in aqueous PAH concentrations with potential applications for continuous on-line monitoring strategies and binding/adsorption studies in heterogeneous samples.

  4. Polyethylene Glycol as Support and Phase Transfer Catalyst in Aqueous Palladium-catalyzed Liquid-phase Synthesis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Excellent yields and purity were obtained in the aqueous medium Suzuki, Sonogashira, Stille and Heck reactions using palladium (Ⅱ) as catalyst in liquid phase synthesis. Polyethylene glycol (PEG) acted as soluble polymeric support and phase transfer catalyst as well.

  5. Structure and phase behavior of aqueous methylcellulose solutions

    Science.gov (United States)

    McAllister, John; Schmidt, Peter; Lodge, Timothy; Bates, Frank

    2015-03-01

    Cellulose ethers (CE) constitute a multi-billion dollar industry, and have found end uses in a broad array of applications from construction materials, food products, personal care products, and pharmaceuticals for more than 80 years. Methylcellulose (MC, with the trade name METHOCEL™) is a CE in which there is a partial substitution of -OH groups with -OCH3 groups. This results in a polymer that is water-soluble at low temperatures, and aqueous solutions of MC display gelation and phase separation at higher temperatures. The nature of MC gelation has been debated for many years, and this project has made significant advances in the understanding of the solution properties of CEs. We have characterized a fibrillar structure of MC gels by cryogenic transmission electron microscopy (cryo-TEM) and small angle neutron scattering (SANS). Using light scattering, turbidity measurements, and dynamic mechanical spectroscopy (DMS) we report that MC microphase separates by nucleation and growth of fibril aggregates, and is a different process from LCST phase separation.

  6. Aqueous Two Phase System Assisted Self-Assembled PLGA Microparticles

    Science.gov (United States)

    Yeredla, Nitish; Kojima, Taisuke; Yang, Yi; Takayama, Shuichi; Kanapathipillai, Mathumai

    2016-06-01

    Here, we produce poly(lactide-co-glycolide) (PLGA) based microparticles with varying morphologies, and temperature responsive properties utilizing a Pluronic F127/dextran aqueous two-phase system (ATPS) assisted self-assembly. The PLGA polymer, when emulsified in Pluronic F127/dextran ATPS, forms unique microparticle structures due to ATPS guided-self assembly. Depending on the PLGA concentration, the particles either formed a core-shell or a composite microparticle structure. The microparticles facilitate the simultaneous incorporation of both hydrophobic and hydrophilic molecules, due to their amphiphilic macromolecule composition. Further, due to the lower critical solution temperature (LCST) properties of Pluronic F127, the particles exhibit temperature responsiveness. The ATPS based microparticle formation demonstrated in this study, serves as a novel platform for PLGA/polymer based tunable micro/nano particle and polymersome development. The unique properties may be useful in applications such as theranostics, synthesis of complex structure particles, bioreaction/mineralization at the two-phase interface, and bioseparations.

  7. Aqueous-phase behavior of natural glycolipid biosurfactant mannosylerythritol lipid A: sponge, cubic, and lamellar phases.

    Science.gov (United States)

    Imura, Tomohiro; Hikosaka, Yusuke; Worakitkanchanakul, Wannasiri; Sakai, Hideki; Abe, Masahiko; Konishi, Masaaki; Minamikawa, Hiroyuki; Kitamoto, Dai

    2007-02-13

    The aqueous-phase behavior of mannosylerythritol lipid A (MEL-A), which is a glycolipid biosurfactant produced from vegetable oils by yeast strains of the genus Pseudozyma, was investigated using polarized optical microscopy, small-angle X-ray scattering (SAXS), and differential scanning calorimetry (DSC). MEL-A was found to self-assemble into a variety of distinctive lyotropic liquid crystals including sponge (L3), bicontinuous cubic (V2), and lamella (Lalpha) phases. On the basis of SAXS measurements, we determined the structure of the liquid crystals. The estimated lattice constant for Lalpha was 3.58 nm. DSC measurement revealed that the phase transition enthalpies from the liquid crystal to the fluid isotropic phase were in the range of 0.22-0.44 kJ/mol. Although the present MEL-A phase diagram closely resembled that obtained from relatively hydrophobic poly(oxyethylene) or fluorinated surfactants, the MEL-A L3 region was spread considerably over a wide temperature range (20-65 degrees C) compared to L3 of those surfactants: this is probably due to the unique structure which is molecularly engineered by microorganisms. In this paper, we clarify the aqueous phase diagram of the natural glycolipid biosurfactant MEL-A, and we suggest that the obtained lyotropic crystals are potentially useful as novel nanostructured biomaterials. PMID:17279642

  8. Advanced Aqueous Phase Catalyst Development using Combinatorial Methods Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Combinatorial methods are proposed to develop advanced Aqueous Oxidation Catalysts (AOCs) with the capability to mineralize organic contaminants present in...

  9. Analytic approach to the motion of cosmological phase transition fronts

    International Nuclear Information System (INIS)

    We consider the motion of planar phase-transition fronts in first-order phase transitions of the Universe. We find the steady state wall velocity as a function of a friction coefficient and thermodynamical parameters, taking into account the different hydrodynamic modes of propagation. We obtain analytical approximations for the velocity by using the thin wall approximation and the bag equation of state. We compare our results to those of numerical calculations and discuss the range of validity of the approximations. We analyze the structure of the stationary solutions. Multiple solutions may exist for a given set of parameters, even after discarding non-physical ones. We discuss which of these will be realized in the phase transition as the stationary wall velocity. Finally, we discuss on the saturation of the friction at ultra-relativistic velocities and the existence of runaway solutions.

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

    Science.gov (United States)

    Kneafsey, Timothy J.; Hunt, James R.

    2004-02-01

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

  11. A green deep eutectic solvent-based aqueous two-phase system for protein extracting

    International Nuclear Information System (INIS)

    Highlights: • A strategy for the protein purification with a deep eutectic solvent(DES)-based aqueous two-phase system. • Choline chloride-glycerin DES was selected as the extraction solvent. • Bovine serum albumin and trypsin were used as the analytes. • Aggregation phenomenon was detected in the mechanism research. - Abstract: As a new type of green solvent, deep eutectic solvent (DES) has been applied for the extraction of proteins with an aqueous two-phase system (ATPS) in this work. Four kinds of choline chloride (ChCl)-based DESs were synthesized to extract bovine serum albumin (BSA), and ChCl-glycerol was selected as the suitable extraction solvent. Single factor experiments have been done to investigate the effects of the extraction process, including the amount of DES, the concentration of salt, the mass of protein, the shaking time, the temperature and PH value. Experimental results show 98.16% of the BSA could be extracted into the DES-rich phase in a single-step extraction under the optimized conditions. A high extraction efficiency of 94.36% was achieved, while the conditions were applied to the extraction of trypsin (Try). Precision, repeatability and stability experiments were studied and the relative standard deviations (RSD) of the extraction efficiency were 0.4246% (n = 3), 1.6057% (n = 3) and 1.6132% (n = 3), respectively. Conformation of BSA was not changed during the extraction process according to the investigation of UV–vis spectra, FT-IR spectra and CD spectra of BSA. The conductivity, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to explore the mechanism of the extraction. It turned out that the formation of DES–protein aggregates play a significant role in the separation process. All the results suggest that ChCl-based DES-ATPS are supposed to have the potential to provide new possibilities in the separation of proteins

  12. A green deep eutectic solvent-based aqueous two-phase system for protein extracting

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Kaijia; Wang, Yuzhi, E-mail: wyzss@hnu.edu.cn; Huang, Yanhua; Li, Na; Wen, Qian

    2015-03-15

    Highlights: • A strategy for the protein purification with a deep eutectic solvent(DES)-based aqueous two-phase system. • Choline chloride-glycerin DES was selected as the extraction solvent. • Bovine serum albumin and trypsin were used as the analytes. • Aggregation phenomenon was detected in the mechanism research. - Abstract: As a new type of green solvent, deep eutectic solvent (DES) has been applied for the extraction of proteins with an aqueous two-phase system (ATPS) in this work. Four kinds of choline chloride (ChCl)-based DESs were synthesized to extract bovine serum albumin (BSA), and ChCl-glycerol was selected as the suitable extraction solvent. Single factor experiments have been done to investigate the effects of the extraction process, including the amount of DES, the concentration of salt, the mass of protein, the shaking time, the temperature and PH value. Experimental results show 98.16% of the BSA could be extracted into the DES-rich phase in a single-step extraction under the optimized conditions. A high extraction efficiency of 94.36% was achieved, while the conditions were applied to the extraction of trypsin (Try). Precision, repeatability and stability experiments were studied and the relative standard deviations (RSD) of the extraction efficiency were 0.4246% (n = 3), 1.6057% (n = 3) and 1.6132% (n = 3), respectively. Conformation of BSA was not changed during the extraction process according to the investigation of UV–vis spectra, FT-IR spectra and CD spectra of BSA. The conductivity, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to explore the mechanism of the extraction. It turned out that the formation of DES–protein aggregates play a significant role in the separation process. All the results suggest that ChCl-based DES-ATPS are supposed to have the potential to provide new possibilities in the separation of proteins.

  13. Two-phase aqueous micellar systems: an alternative method for protein purification

    Directory of Open Access Journals (Sweden)

    Rangel-Yagui C. O.

    2004-01-01

    Full Text Available Two-phase aqueous micellar systems can be exploited in separation science for the extraction/purification of desired biomolecules. This article reviews recent experimental and theoretical work by Blankschtein and co-workers on the use of two-phase aqueous micellar systems for the separation of hydrophilic proteins. The experimental partitioning behavior of the enzyme glucose-6-phosphate dehydrogenase (G6PD in two-phase aqueous micellar systems is also reviewed and new results are presented. Specifically, we discuss very recent work on the purification of G6PD using: i a two-phase aqueous micellar system composed of the nonionic surfactant n-decyl tetra(ethylene oxide (C10E4, and (ii a two-phase aqueous mixed micellar system composed of C10E4 and the cationic surfactant decyltrimethylammonium bromide (C10TAB. Our results indicate that the two-phase aqueous mixed (C10E4/C10TAB micellar system can improve significantly the partitioning behavior of G6PD relative to that observed in the two-phase aqueous C10E4 micellar system.

  14. Thermal mixing of phases numerical and analytical studies

    CERN Document Server

    Gleiser, Marcello

    1995-01-01

    The dynamics of phase transitions plays a crucial r\\^ole in the so-called interface between high energy particle physics and cosmology. Many of the interesting results generated during the last fifteen years or so rely on simplified assumptions concerning the complex mechanisms typical of nonequilibrium field theories. In particular, whenever first order phase transitions are invoked, the metastable background is assumed to be sufficiently smooth to justify the use of homogeneous nucleation theory in the computation of nucleation rates of critical bubbles. In this talk I present the results of numerical simulations which were designed to quantify ``smoothness''; that is, how the contribution from nonperturbative subcritical fluctuations may spoil the homogeneity assumption of nucleation theory. I then show how the numerical results can be understood {\\it quantitatively} in terms of a simple analytical model of subcritical thermal fluctuations. Encouraged by the success of the model in matching the numerical r...

  15. Hydrogen production by aqueous phase reforming of light oxygenated hydrocarbons

    Science.gov (United States)

    Shabaker, John William

    Aqueous phase reforming (APR) of renewable oxygenated hydrocarbons (e.g., methanol, ethylene glycol, glycerol, sorbitol, glucose) is a promising new technology for the catalytic production of high-purity hydrogen for fuel cells and chemical processing. Supported Pt catalysts are effective catalysts for stable and rapid H2 production at temperatures near 500 K (H 2 turnover frequencies near 10 min-1). Inexpensive Raney Ni-based catalysts have been developed using a combination of fundamental and high-throughput studies that have similar catalytic properties as Pt-based materials. Promotion of Raney Ni with Sn by controlled surface reaction of organometallic tin compounds is necessary to control formation of thermodynamically-favorable alkane byproducts. Detailed characterization by Mossbauer spectroscopy, electron microscopy, adsorption studies, and x-ray photoelectron spectroscopy (XPS/ESCA) has shown that NiSn alloys are formed during heat treatment, and may be responsible for enhanced stability and selectivity for hydrogen production. Detailed kinetic studies led to the development of a kinetic mechanism for the APR reaction on Pt and NiSn catalysts, in which the oxygenate decomposes through C--H and O--H cleavage, followed by C--C cleavage and water gas shift of the CO intermediate. The rate limiting step on Pt surfaces is the initial dehydrogenation, while C--C cleavage appears rate limiting over NiSn catalysts. Tin promotion of Raney Ni catalysts suppresses C--O bond scission reactions that lead to alkane formation without inhibiting fast C--C and C--H cleavage steps that are necessary for high rates of reforming. A window of operating temperature, pressure, and reactor residence time has been identified for use of the inexpensive NiSn catalysts as a Pt substitute. Concentrated feed stocks and aggressive pretreatments have been found to counteract catalyst deactivation by sintering in the hydrothermal APR environment and allow stable, long-term production of H

  16. A novel procedure for phase separation in dispersive liquid-liquid microextraction based on solidification of the aqueous phase.

    Science.gov (United States)

    March, J G; Cerdà, V

    2016-08-15

    In this paper, an alternative for handling the organic phase after a dispersive liquid-liquid microextraction using organic solvents lighter than water is presented. It is based on solidification (at -18°C) of the aqueous phase obtained after centrifugation, and the decantation, collection and analysis of the liquid organic layer. The extraction of nicotine in toluene, and its determination in eggplant samples was conducted as a proof of concept. The study has been carried out using standards prepared in water and the formation of the dispersion was assisted by sonication. The organic extract was analysed using gas chromatography coupled to mass spectrometry. Satisfactory analytical figures of merit as: limit of detection (0.4µgL(-1), 2ngg(-1) wet sample), limit of quantification (1.2µgL(-1), 6.5ngg(-1) wet sample), within-day precision (RSD=7%), and linearity interval (up to 384µgL(-1) nicotine) were achieved. It constituted a contribution to the handling of organic extracts after microextraction processes. PMID:27260454

  17. Chemiluminescence studies between aqueous phase synthesized mercaptosuccinic acid capped cadmium telluride quantum dots and luminol-H2O2

    Science.gov (United States)

    Kaviyarasan, Kulandaivelu; Anandan, Sambandam; Mangalaraja, Ramalinga Viswanathan; Asiri, Abdullah M.; Wu, Jerry J.

    2016-08-01

    Mercaptosuccinic acid capped Cadmium telluride quantum dots have been successfully synthesized via aqueous phase method. The products were well characterized by a number of analytical techniques, including FT-IR, XRD, HRTEM, and a corrected particle size analysis by the statistical treatment of several AFM measurements. Chemiluminescence experiments were performed to explore the resonance energy transfer between chemiluminescence donor (luminol-H2O2 system) and acceptor CdTe QDs. The combination of such donor and acceptor dramatically reduce the fluorescence while compared to pristine CdTe QDs without any exciting light source, which is due to the occurrence of chemiluminescence resonance energy transfer (CRET) processes.

  18. Chemiluminescence studies between aqueous phase synthesized mercaptosuccinic acid capped cadmium telluride quantum dots and luminol-H2O2.

    Science.gov (United States)

    Kaviyarasan, Kulandaivelu; Anandan, Sambandam; Mangalaraja, Ramalinga Viswanathan; Asiri, Abdullah M; Wu, Jerry J

    2016-08-01

    Mercaptosuccinic acid capped Cadmium telluride quantum dots have been successfully synthesized via aqueous phase method. The products were well characterized by a number of analytical techniques, including FT-IR, XRD, HRTEM, and a corrected particle size analysis by the statistical treatment of several AFM measurements. Chemiluminescence experiments were performed to explore the resonance energy transfer between chemiluminescence donor (luminol-H2O2 system) and acceptor CdTe QDs. The combination of such donor and acceptor dramatically reduce the fluorescence while compared to pristine CdTe QDs without any exciting light source, which is due to the occurrence of chemiluminescence resonance energy transfer (CRET) processes. PMID:27131144

  19. Formation of aqueous-phase α-hydroxyhydroperoxides (α-HHP): potential atmospheric impacts

    OpenAIRE

    Zhao, R.; A. K. Y. Lee; Soong, R; Simpson, A. J.; J. P. D. Abbatt

    2013-01-01

    The focus of this work is on quantifying the degree of the aqueous-phase formation of α-hydroxyhydroperoxides (α-HHPs) via reversible nucleophilic addition of H2O2 to aldehydes. Formation of this class of highly oxygenated organic hydroperoxides represents a poorly characterized aqueous-phase processing pathway that may lead to enhanced SOA formation and aerosol toxicity. Specifically, the equilibrium constants of α-HHP formation have been determi...

  20. Formation of aqueous-phase α-hydroxyhydroperoxides (α-HHP): potential atmospheric impacts

    OpenAIRE

    Zhao, R.; A. K. Y. Lee; Soong, R; Simpson, A. J.; J. P. D. Abbatt

    2013-01-01

    The focus of this work is on quantifying the degree of the aqueous-phase formation of α-hydroxyhydroperoxides (α-HHPs) via reversible nucleophilic addition of H2O2 to aldehydes. Formation of this class of highly oxygenated organic hydroperoxides represents a poorly characterized aqueous-phase processing pathway that may lead to enhanced SOA formation and aerosol toxicity. Specifically, the equilibrium constants of α-HHP formation have been determined using proton nuclear-magnetic-resonance (1...

  1. Influence of aqueous phase emulsifiers on lipid oxidation in water-in-walnut oil emulsions.

    Science.gov (United States)

    Yi, Jianhua; Zhu, Zhenbao; McClements, D Julian; Decker, Eric A

    2014-03-01

    Effects of selected aqueous phase emulsifiers on lipid oxidative stability of water-in-walnut oil (W/O) emulsions stabilized by polyglycerol polyricinoleate (PGPR) were evaluated. The formation of primary oxidation products (lipid hydroperoxides) and secondary oxidation products (headspace hexanal) increased with increasing dodecyltrimethylammonium bromide (DTAB) concentration (0.1-0.2 wt % of emulsions). In contrast, the addition of sodium dodecyl sulfate (SDS) in the aqueous phase reduced lipid hydroperoxide and hexanal formation. In addition, the presence of Tween 20 in the aqueous phase did not significantly influence lipid oxidation rates in W/O emulsions compared to the control (without Tween 20). Whey protein isolate (WPI) was observed to inhibit lipid oxidation in the W/O emulsions (0.05-0.2 wt % of emulsions). Aqueous phase pH had an important impact on the antioxidant capability of WPI, with higher pH improving its ability to inhibit lipid oxidation. The combination of WPI and DTAB in the aqueous phase suppressed the prooxidant effect of DTAB. The combination of WPI and SDS resulted in improved antioxidant activity, with inhibition being greater at pH 7.0 than at pH 3.0. These results suggest that the oxidative stability of W/O emulsions could be improved by the use of suitable emulsifiers in the aqueous phase. PMID:24446832

  2. Separation of aqueous two-phase polymer systems in microgravity

    Science.gov (United States)

    Vanalstine, J. M.; Harris, J. M.; Synder, S.; Curreri, P. A.; Bamberger, S. B.; Brooks, D. E.

    1984-01-01

    Phase separation of polymer systems in microgravity is studied in aircraft flights to prepare shuttle experiments. Short duration (20 sec) experiments demonstrate that phase separation proceeds rapidly in low gravity despite appreciable phase viscosities and low liquid interfacial tensions (i.e., 50 cP, 10 micro N/m). Ostwald ripening does not appear to be a satisfactory model for the phase separation mechanism. Polymer coated surfaces are evaluated as a means to localize phases separated in low gravity. Contact angle measurements demonstrate that covalently coupling dextran or PEG to glass drastically alters the 1-g wall wetting behavior of the phases in dextran-PEG two phase systems.

  3. Phase Separation Behavior and System Properties of Aqueous Two-Phase Systems with Polyethylene Glycol and Different Salts: Experiment and Correlation

    OpenAIRE

    Haihua Yuan; Yang Liu; Wanqian Wei; Yongjie Zhao

    2015-01-01

    The phase separation behaviors of PEG1000/sodium citrate, PEG4000/sodium citrate, PEG1000/ammonium sulfate, and PEG4000/ammonium sulfate aqueous two-phase systems were investigated, respectively. There are two distinct situations for the phase separation rate in the investigated aqueous two-phase systems: one state is top-continuous phase with slow phase separation rate and strong bottom-continuous phase with fast phase separation rate and weak volume ratio dependence. The system properties s...

  4. Nickel/ruthenium catalyst and method for aqueous phase reactions

    Science.gov (United States)

    Elliott, Douglas C.; Sealock, John L.

    1998-01-01

    A method of hydrogenation using a catalyst in the form of a plurality of porous particles wherein each particle is a support having nickel metal catalytic phase or reduced nickel deposited thereon in a first dispersed phase and an additional ruthenium metal deposited onto the support in a second dispersed phase. The additional ruthenium metal is effective in retarding or reducing agglomeration or sintering of the nickel metal catalytic phase thereby increasing the life time of the catalyst during hydrogenation reactions.

  5. Extraction Equilibrium of Acrylic Acid by Aqueous Two-Phase Systems Using Hydrophilic Ionic Liquids

    International Nuclear Information System (INIS)

    As an effective method for extraction of acrylic acid, aqueous two-phase systems based on morpholinium ionic liquids were used in this study. Effects of the alkyl chain length of cation in morpholinium ionic liquids on phase diagram and extraction efficiencies were investigated. Experimental results show that aqueous two phase systems can be formed by adding appropriate amount of morpholinium ionic liquids to aqueous K2HPO4 solutions. It can be found that the ability of morpholinium ionic liquids for phase separation followed the order [HMMor][Br]>[OMMor][Br]>[BMMor][Br]>[EMMor][Br]. There was little difference between binodal curves of imidazolium ionic liquids and those of morpholinium ionic liquids. 50-90% of the extraction efficiency was observed for acrylic acid by aqueous two phase extraction of acrylic acid with morpholinium ionic liquids. It can be concluded that morpholinium ionic liquids/K2HPO4 were effective for aqueous two phases extraction of acrylic acid comparing to imidazolium ionic liquids/K2HPO4 systems because of their lower cost

  6. Synergistic extraction of transition metal cations from aqueous media by two separated organic phases

    International Nuclear Information System (INIS)

    We have therefore initiated novel approaches to the study of the mechanism of the synergistic extraction of metal ions by means of two separated organic phases, which are brought in contact with the same aqueous phase. The present work is concerned with the extraction of transition metals and actinides ions from nitric acid by chelating agents e.g., HTTA thenoyltrifluoroacetone in a diluent - the first organic phase, and by natural donor, e.g., TBP, tri-butyl phosphate in a diluent the second organic phase. The adduct formation was studied by means of spectrochemical and radiochemical methods. In the first approach the aqueous phase was attacked with both organic phases simultanously (the static or parallel extraction). In this method organic phase are separated one from the other. It was shown that even in the absence of mixing, synergism is observed under this experimental conditions. The results indicate, that adduct formation occurs in both organic phases. Nevertheless the enhanchment of extraction in the TBP phase is by far greater than that in the HTTA containing phase. This approach has one disadvatage, viz., the experiments are very time consuming, a typical experiment requiring over 10 days. In order to overcome this difficulty, the following experiments were carried out: the aqueous phase were first shaken with diluent containing an anionic ligand and the phases were allowed to separate. Then the aqueous solution were shaken with diluent containing a netural donor and the phase again were allowed to separate. The concentration of the metal ions in all the phases were determined. The experiments were repeated with an other diluent replacing the first diluent in one or both organic phases. In this way eight sequences of experiments were carried out for each concentration set chosen. The results thus point out that this experimental approach open new possibilities to investigate the mechanism and the kinetics of synergistic extraction processes. (author) the

  7. Propene Hydroformylation by Supported Aqueous-phase Rh-NORBOS Catalysts

    DEFF Research Database (Denmark)

    Riisager, Anders; Eriksen, Kim Michael; Hjortkjær, Jes; Fehrmann, Rasmus

    The gas-phase hydroformylation reaction of propene using supported aqueous-phase (SAP) Rh-NORBOS modified catalysts in a continuous flow reactor has been examined. SAP catalysts supported on six different support materials were made by wet impregnation using solutions of the precursor complex Rh(...

  8. 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.

  9. Hydrate phase equilibria of CO2+N2+aqueous solution of THF, TBAB or TBAF system

    DEFF Research Database (Denmark)

    Sfaxi, Imen Ben Attouche; Durand, Isabelle; Lugo, Rafael;

    2014-01-01

    We report hydrate dissociation conditions of CO2 (15 and 30mol%)+N2 (85 and 70mol%) in the presence of aqueous solutions of THF, TBAB or TBAF. The concentrations of TBAB and TBAF in the aqueous solutions are 5wt% and 9wt% while THF concentration in aqueous solution is 3mol%. Two different...... experimental techniques including isochoric pressure search method and a DSC method are used to measure the hydrate dissociation conditions. A comparison is finally made with the literature data. It is expected that this study provides better understanding of hydrate phase equilibria associated with CO2...... capture. © 2014 Elsevier Ltd....

  10. Plutonium silicate alteration phases produced by aqueous corrosion of borosilicate glass

    International Nuclear Information System (INIS)

    Borosilicate glasses loaded with ∼10 wt % plutonium were found to produce plutonium-silicate alteration phases upon aqueous corrosion under a range of conditions. The phases observed were generally rich in lanthanide (Ln) elements and were related to the lanthanide orthosilicate phases of the monoclinic Ln2SiO5 type. The composition of the phases was variable regarding [Ln]/[Pu] ratio, depending upon type of corrosion test and on the location within the alteration layer. The formation of these phases likely has implications for the incorporation of plutonium into silicate alteration phases during corrosion of titanate ceramics, high-level waste glasses, and spent nuclear fuel

  11. The role of bio-ethanol in aqueous phase reforming to sustainable hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Tokarev, A.V.; Murzina, E.V.; Eraenen, K.; Murzin, D.Yu. [Aabo Akademi University, Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Biskopsgatan 8, FIN-20500 Turku/Aabo (Finland); Kirilin, A.V. [Aabo Akademi University, Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Biskopsgatan 8, FIN-20500 Turku/Aabo (Finland); Zelinsky Institute of Organic Chemistry, Moscow (Russian Federation); Kustov, L.M. [Zelinsky Institute of Organic Chemistry, Moscow (Russian Federation); Mikkola, J.-P. [Aabo Akademi University, Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Biskopsgatan 8, FIN-20500 Turku/Aabo (Finland); Umeaa University, Technical Chemistry Department of Chemistry, Chemical-Biological Centre, Umeaa (Sweden)

    2010-11-15

    Aqueous Phase Reforming (APR) has during the recent years emerged as a potent, alternative means of processing raw materials of biological origin to component suitable as chemicals and fuel components. In contrary to e.g. steam reforming, aqueous phase reforming bares the promise of lower temperatures in processing which gives rise to potential of reduced energy consumption in the upgrading process itself. Aqueous phase reforming was studied over Pt/Al2O3 at 225 C. Stable catalyst performance and high selectivity was observed. Upon a comparison of two 'bio-alcohols', bio-ethanol and Sorbitol (a sugar alcohol), the latter one is a better feedstock from overall energy utilization viewpoint but the use of it results in a broad range of products. Interestingly, in the case of sorbitol-ethanol mixtures, an improvement in the hydrogen yield was observed. (author)

  12. Liquid-liquid phase separation in mixed organic/inorganic single aqueous aerosol droplets

    OpenAIRE

    Stewart, D J; Cai, C.; Nayler, J.; Preston, T. C.; J. P. Reid; Krieger, U. K.; Marcolli, C.; Zhang, Y H

    2015-01-01

    Direct measurements of the phase separation relative humidity (RH) and morphology of aerosol particles consisting of liquid organic and aqueous inorganic domains are presented. Single droplets of mixed phase composition are captured in a gradient force optical trap, and the evolving size, refractive index (RI), and morphology are characterized by cavity-enhanced Raman spectroscopy. Starting at a RH above the phase separation RH, the trapped particle is dried to lower RH and the transition to ...

  13. Selective separation of protein and saccharides by ionic liquids aqueous two-phase systems

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In the present work,it was found that aqueous solution of a hydrophilic ionic liquid (IL),1-butyl-3-methylimidazolium dicyanamide ([C4mim][N(CN)2]),could be separated into an aqueous two-phase system (ATPS) by inorganic salts such as K2HPO4 and K3PO4.The top phase is IL-rich,while the bottom phase is phosphate-rich.It was shown that 82.7%-100% bovine serum albumin (BSA) could be enriched into the top phase and almost quantitative saccharides (arabinose,glucose,sucrose,raffinose or dextran) were preferentially extracted into the bottom phase in a single-step extraction by [C4mim][N(CN)2] + K2HPO4 ATPS.The extraction efficiency of BSA from the aqueous saccharide solutions was influenced by the molecular structure of saccharides.The conductivity,dynamic light scattering (DLS) and transmission electron microscopy (TEM) were combined to investigate the microstructure of the IL-rich top phase and the possible mechanism for the selective separation.It is suggested that the formation of the IL aggregate and the IL aggregate-BSA complex plays a significant role in the separation of BSA from aqueous saccharide solutions.This is the first example for the selective separation by ILs-based ATPSs.It is expected that these findings would have potential applications in bio-analysis,separation,and IL recycle.

  14. Subcritical hydrothermal liquefaction of barley straw in fresh water and recycled aqueous phase

    DEFF Research Database (Denmark)

    Zhu, Zhe; Toor, Saqib; Rosendahl, Lasse;

    2014-01-01

    addition of recycling aqueous phase in HTL process, it is expected that the amount of the waste water and energy consumption can be reduced. The effect of water recirculation on product yield and properties was investigated in this study. The results showed that bio-oil yield was 34.85 wt% when the barley...... straw was first liquefied in fresh distilled water with the presence of K2CO3 catalyst at 300 C as the reference run. Afterwards, the aqueous phase which is obtained from liquefaction process in the previous run was recycled and used as the reaction medium from the second to the fourth run. With the...

  15. CATALYTIC GENERATION OF HYDROGEN FROM BIOMASS DERIVED LACTIC ACID VIA AQUEOUS PHASE REFORMING

    OpenAIRE

    Bosilj, Monika

    2015-01-01

    Hydrogen production from aqueous phase reforming (APR) of organic acids in aqueous phase and from residue of a biomass decomposition process over 3 wt% Pt/ZrO2 has been studied in the absence and presence of barium ions. The results have been compared with Pt/TiO2, Pt/C and Ni/C catalysts. Having identified barium hydroxide as a promising reagent in combination with Pt/ZrO2 catalyst for the hydrogen production out of organic acids, the method for the lactic acid conversion was extended. Lacti...

  16. Phase Changes of Monosulfoaluminate in NaCl Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Seyoon Yoon

    2016-05-01

    Full Text Available Monosulfoaluminate (Ca4Al2(SO4(OH12∙6H2O plays an important role in anion binding in Portland cement by exchanging its original interlayer ions (SO42− and OH− with chloride ions. In this study, scanning transmission X-ray microscope (STXM, X-ray absorption near edge structure (XANES spectroscopy, and X-ray diffraction (XRD were used to investigate the phase change of monosulfoaluminate due to its interaction with chloride ions. Pure monosulfoaluminate was synthesized and its powder samples were suspended in 0, 0.1, 1, 3, and 5 M NaCl solutions for seven days. At low chloride concentrations, a partial dissolution of monosulfoaluminate formed ettringite, while, with increasing chloride content, the dissolution process was suppressed. As the NaCl concentration increased, the dominant mechanism of the phase change became ion exchange, resulting in direct phase transformation from monosulfoaluminate to Kuzel’s salt or Friedel’s salt. The phase assemblages of the NaCl-reacted samples were explored using thermodynamic calculations and least-square linear combination (LC fitting of measured XANES spectra. A comprehensive description of the phase change and its dominant mechanism are discussed.

  17. Roles of Mineralogical Phases in Aqueous Carbonation of Steelmaking Slag

    Directory of Open Access Journals (Sweden)

    Huining Zhang

    2016-05-01

    Full Text Available Mineralogical phases of steelmaking slags have significant influences on the carbonation of the slags. In this paper, the effects of temperature and reaction time on the conversion of calcium-related phases and the carbonation degree of a slag sample were studied. The experimental conditions were a liquid-to-solid ratio of 20 mL/g, a carbon dioxide flow rate of 1 L/min and a slag particle size of 38–75 μm. The results show that the optimum carbonation temperature and reaction time are 60 °C and 90 min, respectively, and calcite phase content is about 26.78% while the conversion rates of Ca3Al2O6, CaSiO3, Ca2SiO4 and free CaO are about 40%, 42.46%, 51% and 100%, respectively, and the carbon dioxide sequestration efficiency is about 170 g/kg slag.

  18. Multi-analyte approach for the determination of ng L-1 levels of steroid hormones in unidentified aqueous samples

    International Nuclear Information System (INIS)

    Since the 1970s, many analytical methods for the detection of illegal growth promoters, such as thyreostats, anabolics, β-agonists and corticosteroids have been developed for a wide range of matrices of animal origin, including meat, fat, organ tissue, urine and faeces. The aim of this study was to develop an analytical method for the determination of ng L-1 levels of estrogens, gestagens, androgens (EGAs) and corticosteroids in aqueous preparations (i.e. drinking water, drinking water supplements), commercially available on the 'black' market. For this, extraction was performed with Bakerbond C18 speedisk, a technique commonly used in environmental analysis. After fractionation, four fractions were collected using a methanol:water gradient program. Gas chromatography coupled to electron impact multiple mass spectrometry (GC-EI-MS2) screening for the EGAs was carried out on the derivatized extracts. For the detection of corticosteroids, gas chromatography coupled to negative chemical ionization mass spectrometry (GC-NCI-MS) was used after oxidation of the extracts. Confirmation was done by liquid chromatography coupled to electrospray ionization multiple mass spectrometry (LC-ESI-MS2). The combined use of GC and LC coupled to MS enabled the identification and quantification of anabolics and corticosteroids at the low ng L-1 level. This study demonstrated the occurrence of both androgens and corticosteroids in different commercial aqueous samples

  19. Multi-analyte approach for the determination of ng L(-1) levels of steroid hormones in unidentified aqueous samples.

    Science.gov (United States)

    Noppe, H; Verheyden, K; Gillis, W; Courtheyn, D; Vanthemsche, P; De Brabander, H F

    2007-03-14

    Since the 1970s, many analytical methods for the detection of illegal growth promoters, such as thyreostats, anabolics, beta-agonists and corticosteroids have been developed for a wide range of matrices of animal origin, including meat, fat, organ tissue, urine and faeces. The aim of this study was to develop an analytical method for the determination of ng L(-1) levels of estrogens, gestagens, androgens (EGAs) and corticosteroids in aqueous preparations (i.e. drinking water, drinking water supplements), commercially available on the 'black' market. For this, extraction was performed with Bakerbond C18 speedisk, a technique commonly used in environmental analysis. After fractionation, four fractions were collected using a methanol:water gradient program. Gas chromatography coupled to electron impact multiple mass spectrometry (GC-EI-MS2) screening for the EGAs was carried out on the derivatized extracts. For the detection of corticosteroids, gas chromatography coupled to negative chemical ionization mass spectrometry (GC-NCI-MS) was used after oxidation of the extracts. Confirmation was done by liquid chromatography coupled to electrospray ionization multiple mass spectrometry (LC-ESI-MS2). The combined use of GC and LC coupled to MS enabled the identification and quantification of anabolics and corticosteroids at the low ng L(-1) level. This study demonstrated the occurrence of both androgens and corticosteroids in different commercial aqueous samples. PMID:17386692

  20. On-chip aqueous two-phase system (ATPS) formation, consequential self-mixing, and their influence on drop-to-drop aqueous two-phase extraction kinetics

    Science.gov (United States)

    Wijethunga, Pavithra A. L.; Moon, Hyejin

    2015-09-01

    Aqueous two-phase systems (ATPSs) allow an advantageous aqueous two-phase extraction process (ATPE), a special type of liquid-liquid extraction. Compared with conventional liquid-liquid extraction using aqueous/organic extraction media, ATPE is known to provide relatively easy mass transfer and a gentle environment for biological separation applications. Considering the recent interest in microscale ATPE, we aimed to study (i) the potential of preparing ATPS droplets on a digital microfluidic device, and (ii) the influence of the fluidic dynamics created during the formation of ATPS, with the goal of enhancing on-chip ATPE process. On-chip ATPS formation was evaluated by preparing a series of ATPSs on electrowetting on dielectric digital microfluidic chips and comparing their characteristics with the same ATPSs prepared at macroscale using conventional procedures. An enhanced on-chip drop-to-drop ATPE process was achieved by incorporating a self-mixing condition created during ATPSformation. Results indicate a successful on-chip ATPS preparation as well as enhanced extraction performance by self-mixing in the absence of forced mixing. Findings of this research suggest an alternative, simple, yet adequate technique to provide mixing for on-chip applications, such as sample preparation in portable microfluidics, for which it is unfavorable to implement complicated mixing sequences or complex device geometries.

  1. Phase Behavior of Light Gases in Hydrocarbon and Aqueous Solvents.

    Energy Technology Data Exchange (ETDEWEB)

    Gasem, K.A.M.; Robinson, R.L., Jr.; Gao, W.; Ratzalff, D.W.

    1997-10-01

    Under previous support from the Department of Energy, an experimental facility has been established and operated to measure valuable vapor-liquid equilibrium data for systems of interest in the production and processing of coal fluids. To facilitate the development and testing of models for prediction of the phase behavior for such systems, we have acquired substantial amounts of data on the equilibrium phase compositions for binary mixtures of heavy hydrocarbon solvents with a variety of supercritical solutes, including hydrogen, methane, ethane, carbon monoxide, and carbon dioxide. The present project focuses on measuring the phase behavior of light gases and water in Fischer-Tropsch (F-T) type solvents at conditions encountered in indirect liquefaction processes and evaluating and developing theoretically-based correlating frameworks to predict the phase behavior of such systems. Specific goals of the proposed work include (a) developing a state-of-the-art experimental facility to permit highly accurate measurements of equilibrium phase compositions (solubilities) of challenging F-T systems, (b) measuring these properties for systematically-selected binary, ternary and molten F-T wax mixtures to provide critically needed input data for correlation development, (c) developing and testing models suitable for describing the phase behavior of such mixtures, and (d) presenting the modeling results in generalized, practical formats suitable for use in process engineering calculations. During the present reporting period, the solubility of carbon monoxide, hydrogen, and nitrogen in n-dodecane were measured using a static equilibrium cell over the temperature range from 344.3 to 410.9 K and pressures to 13.2 MPa. The uncertainty in these new solubility measurements is estimated to be less than 0.001 in mole fraction. The data were analyzed using the Peng-Robinson (PR) equation of state (EOS). In general, the PR EOS represents the experimental data well when two

  2. Lignin solubilization and aqueous phase reforming for the production of aromatic chemicals and hydrogen

    NARCIS (Netherlands)

    Zakzeski, J.; Weckhuysen, B.M.

    2011-01-01

    The solubilization and aqueous phase reforming of lignin, including kraft, soda, and alcell lignin along with sugarcane bagasse, at low temperatures (T≤498 K) and pressures (P≤29 bar) is reported for the first time for the production of aromatic chemicals and hydrogen. Analysis of lignin model compo

  3. Gas-Phase Oxidation of Aqueous Ethanol by Nanoparticle Vanadia/Anatase Catalysts

    DEFF Research Database (Denmark)

    Jørgensen, Betina; Kristensen, Steffen Buus; Kunov-Kruse, Andreas Jonas;

    2009-01-01

    The gas-phase oxidation of aqueous ethanol with dioxygen has been examined with a new nanoparticle V2O5/TiO2 catalyst. Product selectivity could to a large extent be controlled by small alterations of reaction parameters, allowing production of acetaldehyde at a selectivity higher than 90%, near ...

  4. Correlations for the partition behavior of proteins in aqueous two-phase systems

    DEFF Research Database (Denmark)

    Schmidt, A.S.; Andrews, B.A.; Asenjo, J.A.

    1996-01-01

    The effect of protein concentration in partitioning in PEG/ salt aqueous two-phase systems has been investigated. PEG 4000/phosphate systems in the presence of 0% w/w and 8.8% w/w NaCl have been evaluated using amyloglucosidase, subtilisin, and trypsin inhibitor. Also, a PEG 4000/phosphate system...

  5. PHASE BEHAVIOR OF LIGHT GASES IN HYDROGEN AND AQUEOUS SOLVENTS

    Energy Technology Data Exchange (ETDEWEB)

    KHALED A.M. GASEM; ROBERT L. ROBINSON, JR.

    1999-03-31

    Under previous support from the US Department of Energy, an experimental facility has been established and operated to measure valuable vapor-liquid equilibrium data for systems of interest in the production and processing of coal fluids. To facilitate the development and testing of models for prediction of the phase behavior for such systems, we have acquired substantial amounts of data on the equilibrium phase compositions for binary mixtures of heavy hydrocarbon solvents with a variety of supercritical solutes, including hydrogen, methane, ethane, carbon monoxide, and carbon dioxide. The present project focuses on measuring the phase behavior of light gases and water in Fischer-Tropsch (F-T) type solvents at conditions encountered in indirect liquefaction processes and evaluating and developing theoretically-based correlating frameworks to predict the phase behavior of such systems. Specific goals of the proposed work include (a) developing a state-of-the-art experimental facility to permit highly accurate measurements of equilibrium phase compositions (solubilities) of challenging F-T systems, (b) measuring these properties for systematically-selected binary, ternary and molten F-T wax mixtures to provide critically needed input data for correlation development, (c) developing and testing models suitable for describing the phase behavior of such mixtures, and (d) presenting the modeling results in generalized, practical formats suitable for use in process engineering calculations. During the present reporting period, the solubilities of hydrogen in n-hexane, carbon monoxide in cyclohexane, and nitrogen in phenanthrene and pyrene were measured using a static equilibrium cell over the temperature range from 344.3 to 433.2 K and pressures to 22.8 MPa. The uncertainty in these new solubility measurements is estimated to be less than 0.001 in mole fraction. The data were analyzed using the Peng-Robinson (PR) equation of state (EOS). In general, the PR EOS represents

  6. Rapid RNA Exchange in Aqueous Two-Phase System and Coacervate Droplets

    OpenAIRE

    Jia, Tony Z.; Hentrich, Christian; SZOSTAK, JACK W.

    2014-01-01

    Compartmentalization in a prebiotic setting is an important aspect of early cell formation and is crucial for the development of an artificial protocell system that effectively couples genotype and phenotype. Aqueous two-phase systems (ATPSs) and complex coacervates are phase separation phenomena that lead to the selective partitioning of biomolecules and have recently been proposed as membrane-free protocell models. We show in this study through fluorescence recovery after photobleaching (FR...

  7. Toward stable nickel catalysts for aqueous phase reforming of biomass-derived feedstock under reducing and alkaline conditions

    NARCIS (Netherlands)

    Haasterecht, van T.; Ludding, C.C.I.; Jong, de K.P.; Bitter, J.H.

    2014-01-01

    Nickel nanoparticles supported on carbon nanofibers (CNF) can be stabilized in aqueous phase processes at elevated temperatures and pressures by tuning the reaction conditions to control Ni oxidation and leaching. As a showcase, Ni/CNF was used for the production of hydrogen via aqueous phase reform

  8. Electrophoretic mobilities of neutral analytes and electroosmotic flow markers in aqueous solutions of Hofmeister salts

    Czech Academy of Sciences Publication Activity Database

    Křížek, T.; Kubíčková, A.; Hladílková, Jana; Coufal, P.; Heyda, J.; Jungwirth, Pavel

    2014-01-01

    Roč. 35, č. 5 (2014), s. 617-624. ISSN 0173-0835 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : EOF markers * ion-specific effects * ion-specific mobilization * molecular dynamics simulations * neutral analytes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.028, year: 2014

  9. Aqueous-phase story of isoprene - A mini-review and reaction with HONO

    Science.gov (United States)

    Rudziński, Krzysztof J.; Szmigielski, Rafał; Kuznietsova, Inna; Wach, Paulina; Staszek, Dorota

    2016-04-01

    Isoprene is a major biogenic hydrocarbon emitted to the atmosphere and a well-recognized player in atmospheric chemistry, formation of secondary organic aerosol and air quality. Most of the scientific work on isoprene has focused on the gas-phase and smog chamber processing while direct aqueous chemistry has escaped the major attention because physical solubility of isoprene in water is low. Therefore, this work recollects the results of genuine research carried on atmospherically relevant aqueous-phase transformations of isoprene. It clearly shows that isoprene dissolves in water and reacts in aqueous solutions with common atmospheric oxidants such as hydrogen peroxide, ozone, hydroxyl radicals, sulfate radicals and sulfite radicals. The reactions take place in the bulk of solutions or on the gas-liquid interfaces and often are acid-catalyzed and/or enhanced by light. The review is appended by an experimental study of the aqueous-phase reaction of isoprene with nitrous acid (HONO). The decay of isoprene and formation of new products are demonstrated. The tentative chemical mechanism of the reaction is suggested, which starts with slow decomposition of HONO to NO2 and NO. The aqueous chemistry of isoprene explains the formation of a few tropospheric components identified by scientists yet considered of unknown origin. The reaction of isoprene with sulfate radicals explains formation of the MW 182 organosulfate found in ambient aerosol and rainwater while the reaction of isoprene with HONO explains formation of the MW 129 and MW 229 nitroorganic compounds identified in rainwater. Thus, aqueous transformations of isoprene should not be neglected without evidence but rather considered and evaluated in modeling of atmospheric chemical processes even if alternative and apparently dominant heterogeneous pathways of isoprene transformation, dry or wet, are demonstrated.

  10. Phase Diagrams of the Aqueous Two-Phase Systems of Poly(ethylene glycol)/Sodium Polyacrylate/Salts

    OpenAIRE

    Adalberto Pessoa Junior; Hans-Olof Johansson; Eloi Feitosa

    2011-01-01

    Aqueous two-phase systems consisting of polyethylene glycol (PEG), sodium polyacrylate (NaPAA), and a salt have been studied. The effects of the polymer size, salt type (NaCl, Na2SO4, sodium adipate and sodium azelate) and salt concentrations on the position of the binodal curve were investigated. The investigated PEG molecules had a molar mass of 2,000 to 8,000 g/mol, while that of NaPAA was 8,000 g/mol. Experimental phase diagrams, and tie lines and calculated phase diagrams, based on Flory...

  11. Calcium chloride and calcium bromide aqueous solutions of technical and analytical grade in Lemna bioassay.

    Science.gov (United States)

    Vujević, M; Vidaković-Cifrek, Z; Tkalec, M; Tomíc, M; Regula, I

    2000-11-01

    Saturated water solutions of calcium chloride, calcium bromide and their 1:1 mixture are commonly used as "high density brines" for pressure control in oil wells. To compare the effect of these chemicals of technical grade with the effect of the chemicals of analytical grade the Lemna test was used. The multiplication rate, fresh weight, dry to fresh weight ratio, area covered by plants and chlorophyll content were measured as toxicity parameters. The concentrations of tested chemicals were 0.025, 0.05. 0.075 and 0.1 mol dm(-3). Generally, the chemicals of both technical and analytical grade in concentrations of 0.025 mol dm(-3) stimulated the Lemna minor growth, while tested chemicals in concentrations of 0.05 mol dm(-3) did not affect the growth significantly. The exceptions were results obtained by measuring fresh weight. Most of tested chemicals in concentrations of 0.075 mol dm(-3) and all chemicals in concentrations of 0.1 mol dm(-3) reduced the growth. No major differences between effects of tested chemicals of technical and analytical grade on plant growth were observed, except that tested chemicals of analytical grade in concentrations of 0.1 mol dm(-3) increased dry to fresh weight ratio much stronger than chemicals of technical grade. All tested chemicals in all concentrations increased chlorophyll content. After treatment with chemicals of analytical grade much higher increase of chlorophyll a concentration in comparison to increase of chlorophyll b was noticed, while chemicals of technical grade caused more prominent increase of chlorophyll b. PMID:11057678

  12. Gas-Phase and Aqueous Photocatalytic Oxidation of Methylamine: The Reaction Pathways

    Directory of Open Access Journals (Sweden)

    Anna Kachina

    2007-08-01

    Full Text Available Photocatalytic oxidation (PCO of methylamine (MA on titanium dioxide in aqueous and gaseous phases was studied. A simple batch glass reactor for aqueous PCO and an annular continuous flow reactor for the gas-phase PCO were used. Maximum aqueous PCO efficiency was achieved in alkaline media. Two mechanisms of aqueous PCO—decomposition to formate and ammonia, and oxidation of organic nitrogen directly to nitrite—lead ultimately to CO2, water, ammonia, and nitrate: formate and nitrite were observed as intermediates. A part of the ammonia formed in the reaction was oxidized to nitrite and nitrate. Volatile PCO products of MA included ammonia, nitrogen dioxide (NO2, nitrous oxide (N2O, carbon dioxide, and water. Thermal catalytic oxidation (TCO resulted in the formation of ammonia, hydrogen cyanide, carbon monoxide, carbon dioxide, and water. The gas-phase PCO kinetics is described by the monomolecular Langmuir-Hinshelwood model. No deactivation of TiO2 catalyst was observed.

  13. Ionic liquid-anionic surfactant based aqueous two-phase extraction for determination of antibiotics in honey by high-performance liquid chromatography.

    Science.gov (United States)

    Yang, Xiao; Zhang, Shaohua; Yu, Wei; Liu, Zhongling; Lei, Lei; Li, Na; Zhang, Hanqi; Yu, Yong

    2014-06-01

    An ionic liquid-anionic surfactant based aqueous two-phase extraction was developed and applied for the extraction of tetracycline, oxytetracycline and chloramphenicol in honey. The honey sample was mixed with Na2EDTA aqueous solution. The sodium dodecyl sulfate, ionic liquid 1-octyl-3-methylimidazolium bromide and sodium chloride were added in the mixture. After the resulting mixture was ultrasonically shaken and centrifuged, the aqueous two phase system was formed and analytes were extracted into the upper phase. The parameters affecting the extraction efficiency, such as the volume of ionic liquid, the category and amount of salts, sample pH value, extraction time and temperature were investigated. The limits of detection of tetracycline, oxytetracycline and chloramphenicol were 5.8, 8.2 and 4.2 μg kg(-1), respectively. When the present method was applied to the analysis of real honey samples, the recoveries of analytes ranged from 85.5 to 110.9% and relative standard deviations were lower than 6.9%. PMID:24767438

  14. A portable and autonomous multichannel fluorescence detector for on-line and in situ explosive detection in aqueous phase.

    Science.gov (United States)

    Xin, Yunhong; Wang, Qi; Liu, Taihong; Wang, Lingling; Li, Jia; Fang, Yu

    2012-11-21

    A multichannel fluorescence detector used to detect nitroaromatic explosives in aqueous phase has been developed, which is composed of a five-channel sample-sensor unit, a measurement and control unit, a microcontroller, and a communication unit. The characteristics of the detector as developed are mainly embedded in the sensor unit, and each sensor consists of a fluorescent sensing film, a light emitting diode (LED), a multi-pixel photon counter (MPPC), and an optical module with special bandpass optical filters. Due to the high sensitivity of the sensing film, the small size and low cost of LED and MPPC, the developed detector not only has a better detecting performance and small size, but also has a very low cost - it is an alternative to the device made with an expensive high power lamp and photomultiplier tube. The wavelengths of the five sensors covered extend from the upper UV through the visible spectrum, 370-640 nm, and thereby it possesses the potential to detect a variety of explosives and other hazardous materials in aqueous phase. An additional function of the detector is its ability to function via a wireless network, by which the data recorded by the detector can be sent to the host computer, and at the same time the instructions can be sent to the detector from the host computer. By means of the powerful computing ability of the host computer, and utilizing the classical principal component analysis (PCA) algorithm, effective classification of the analytes is achieved. Furthermore, the detector has been tested and evaluated using NB, PA, TNT and DNT as the analytes, and toluene, benzene, methanol and ethanol as interferent compounds (concentration various from 10 and 60 μM). It has been shown that the detector can detect the four nitroaromatics with high sensitivity and selectivity. PMID:23007322

  15. Modeling of aqueous and organic phase speciation for solvent extraction systems

    International Nuclear Information System (INIS)

    The TRUEX (TRansUranic EXtraction) solvent extraction process has the ability to remove, separate, and recover transuranic (TRU) elements from acidic nuclear waste solutions. A computer model of the TRUEX process is currently being developed for use in flowsheet design and process optimization. The correlations that are to be used in the model for generating extraction distribution ratios are based on chemical mass action principles and require calculation of aqueous and organic phase speciation. Aqueous phase activity coefficients are calculated using methods available in the literature, while the organic phase species are treated in terms of ideal associated solution theory. This approach is demonstrated for the extraction of HNO3, HTcO4, and americium nitrate by n-octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO)---the primary metal extractant in the TRUEX solvent. 23 refs., 5 figs

  16. Explicit modeling of volatile organic compounds partitioning in the atmospheric aqueous phase

    Directory of Open Access Journals (Sweden)

    C. Mouchel-Vallon

    2012-09-01

    Full Text Available The gas phase oxidation of organic species is a multigenerational process involving a large number of secondary compounds. Most secondary organic species are water-soluble multifunctional oxygenated molecules. The fully explicit chemical mechanism GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere is used to describe the oxidation of organics in the gas phase and their mass transfer to the aqueous phase. The oxidation of three hydrocarbons of atmospheric interest (isoprene, octane and α-pinene is investigated for various NOx conditions. The simulated oxidative trajectories are examined in a new two dimensional space defined by the mean oxidation state and the solubility. The amount of dissolved organic matter was found to be very low (<2% under a water content typical of deliquescent aerosols. For cloud water content, 50% (isoprene oxidation to 70% (octane oxidation of the carbon atoms are found in the aqueous phase after the removal of the parent hydrocarbons for low NOx conditions. For high NOx conditions, this ratio is only 5% in the isoprene oxidation case, but remains large for α-pinene and octane oxidation cases (40% and 60%, respectively. Although the model does not yet include chemical reactions in the aqueous phase, much of this dissolved organic matter should be processed in cloud drops and modify both oxidation rates and the speciation of organic species.

  17. Explicit modeling of volatile organic compounds partitioning in the atmospheric aqueous phase

    Directory of Open Access Journals (Sweden)

    C. Mouchel-Vallon

    2013-01-01

    Full Text Available The gas phase oxidation of organic species is a multigenerational process involving a large number of secondary compounds. Most secondary organic species are water-soluble multifunctional oxygenated molecules. The fully explicit chemical mechanism GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere is used to describe the oxidation of organics in the gas phase and their mass transfer to the aqueous phase. The oxidation of three hydrocarbons of atmospheric interest (isoprene, octane and α-pinene is investigated for various NOx conditions. The simulated oxidative trajectories are examined in a new two dimensional space defined by the mean oxidation state and the solubility. The amount of dissolved organic matter was found to be very low (yield less than 2% on carbon atom basis under a water content typical of deliquescent aerosols. For cloud water content, 50% (isoprene oxidation to 70% (octane oxidation of the carbon atoms are found in the aqueous phase after the removal of the parent hydrocarbons for low NOx conditions. For high NOx conditions, this ratio is only 5% in the isoprene oxidation case, but remains large for α-pinene and octane oxidation cases (40% and 60%, respectively. Although the model does not yet include chemical reactions in the aqueous phase, much of this dissolved organic matter should be processed in cloud drops and modify both oxidation rates and the speciation of organic species.

  18. Characterization of fatty acid and triacylglycerol composition in animal fats using silver-ion and non-aqueous reversed-phase high-performance liquid chromatography/mass spectrometry and gas chromatography/flame ionization detection

    Czech Academy of Sciences Publication Activity Database

    Lísa, M.; Netušilová, K.; Franěk, L.; Dvořáková, H.; Vrkoslav, Vladimír; Holčapek, M.

    2011-01-01

    Roč. 1218, č. 42 (2011), s. 7499-7510. ISSN 0021-9673 R&D Projects: GA ČR GA203/09/0139 Institutional research plan: CEZ:AV0Z40550506 Keywords : silver-ion HPLC * non-aqueous reversed-phase HPLC * triacylglycerol Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.531, year: 2011

  19. Preparation,characterization and properties studies of quinine-imprinted polymer in the aqueous phase

    Institute of Scientific and Technical Information of China (English)

    He Jianfeng; Liu Lan; Yang Guilan; Deng Qinying

    2006-01-01

    The uniform-sized spherical molecularly imprinted polymers were successfully prepared through molecular imprinting technology by two-step seed swelling and mini-emulsion polymerization in the aqueous condition using quinine as template molecules and methacrylic acid (MAA)as functional monomer.The polymers were characterized by IR spectra,thermal-weight analysis,scanning electron microscope and laser particle size analysis.The properties of imprinted polymers were investigated in different organic phases and aqueous media.In the organic media,results suggested that polar interactions(hydrogen bonding,ionic interactions)between acidic monomer/polymer and template molecules are mainly responsible for the binding and recognition;whereas in the aqueous medium,a considerable recognition effect was also obtained where the ionic(electrostatic)interaction and hydrophobic interaction play an important role.The experiments of binding different substrates indicated that the MIPs possessed an excellent rebinding ability and inherent selectivity to quinine.

  20. Electrochemical oxidation of loop diuretic furosemide in aqueous acid medium and its analytical application

    Directory of Open Access Journals (Sweden)

    Shikandar D. Bukkitgar

    2016-12-01

    Full Text Available An investigation of oxidative–reductive mechanisms of pharmaceutically important molecules gives us information about the metabolic fact of targeted drug. As compared to recent ongoing, time-consuming and costly techniques, there is an urgent needing for development of a sensitive technique, which can help easy understanding of these pathways. Therefore, in the present work, an effective, low-cost and time-saving technique to investigate the reaction mechanism of furosemide in aqueous acid medium is attempted. Furosemide undergoes two-proton and two-electron transfer reaction. The product obtained was analysed by UV spectra. It was found that the chemical oxidation and electrochemical oxidation of furosemide follows two different pathways. In addition, an effective technique has been developed to determine furosemide in its trace level. Good recoveries and low detection limit accomplished the magnitude of the proposed method. The proposed method was adopted for furosemide determination in human urine and pharmaceutical samples.

  1. Analytical and experimental study of high phase order induction motors

    Science.gov (United States)

    Klingshirn, Eugene A.

    1989-08-01

    Induction motors having more than three phases were investigated to determine their suitability for electric vehicle applications. The objective was to have a motor with a current rating lower than that of a three-phase motor. The name chosen for these is high phase order (HPO) motors. Motors having six phases and nine phases were given the most attention. It was found that HPO motors are quite suitable for electric vehicles, and for many other applications as well. They have characteristics which are as good as or better than three-phase motors for practically all applications where polyphase induction motors are appropriate. Some of the analysis methods are presented, and several of the equivalent circuits which facilitate the determination of harmonic currents and losses, or currents with unbalanced sources, are included. The sometimes large stator currents due to harmonics in the source voltages are pointed out. Filters which can limit these currents were developed. An analysis and description of these filters is included. Experimental results which confirm and illustrate much of the theory are also included. These include locked rotor test results and full-load performance with an open phase. Also shown are oscillograms which display the reduction in harmonic currents when a filter is used with the experimental motor supplied by a non-sinusoidal source.

  2. Fullerene-containing phases obtained from aqueous dispersions of carbon nanoparticles

    Science.gov (United States)

    Rozhkov, S. P.; Kovalevskii, V. V.; Rozhkova, N. N.

    2007-06-01

    The hydration of fullerenes and shungite carbon nanoclusters in aqueous dispersions at various carbon concentrations is studied on frozen samples by EPR with spin probes. It is found that, for stable dispersions of both substances (at carbon concentrations of 0.1 mg/ml), the probe rotation frequency versus 1/T dependences exhibit a plateau in the range 243 257 K, which is probably associated with the peculiarities of freezing of water localized near hydrophobic structures of carbon nanoclusters. Solid phases isolated from supersaturated aqueous dispersions of fullerenes and shungites by slow evaporation of water at temperatures higher than 0°C are examines by electron diffraction and electron microscopy. It is established that obtained films of fullerenes contain at least two phases: fullerite with a face-centered cubic lattice and a phase similar in interplanar spacing and radically different in distribution of intensities of diffraction peaks. It is concluded that this phase is formed by the interaction of fullerenes and water (an analogous phase is found in shungite carbon films). It is found that the morphology of the new crystal phase is characterized by globules of size 20 to 70 nm, for fullerenes, and 10 to 400 nm for shungites. It is established that processes of crystallization of fullerites and fullerene-containing phases are very sensitive to temperature: a decrease in the temperature (within the range from 40 to 1°C) is accompanied by an increase in the new phase content.

  3. Polyvinyl pyrrolidone capped fluorescent anthracene nanoparticles for sensing fluorescein sodium in aqueous solution and analytical application for ophthalmic samples.

    Science.gov (United States)

    Bhopate, Dhanaji P; Mahajan, Prasad G; Garadkar, Kalyanrao M; Kolekar, Govind B; Patil, Shivajirao R

    2015-11-01

    Based on the known complexation ability between polyvinyl pyrrolidone (PVP) and fluorescein sodium (FL Na(+)), fluorescent PVP capped anthracene nanoparticles (PVP-ANPs) were prepared using a reprecipitation method for detection of fluorescein in aqueous solution using the fluorescence resonance energy transfer (FRET) approach. A dynamic light scattering histogram of PVP-ANPs showed narrower particle size distribution and the average particle size was 15 nm. The aggregation-induced enhanced emission (AIEE) of PVP-ANPs was red shifted from its monomer by 1087.22 cm(-1). The maximum emission was seen to occur at 420 nm. The presence of FL Na(+) in the vicinity of PVP-ANPs quenched the fluorescence of PVP-ANPs because of its adsorption on the surface of PVP-ANPs in aqueous suspension. The FL Na(+) and PVP-ANPs were brought close enough, typically to 7.89 nm, which was less than the distance of 10 nm that is required between the energy donor-acceptor molecule for efficient FRET. The quenching results fit into the Stern-Volmer relationship even at temperatures greater than ambient temperatures. The thermodynamic parameters determined from FRET results helped to propose binding mechanisms involving hydrophobic and electrostatic molecular interaction. The fluorescence quenching results were used further to develop an analytical method for estimation of fluorescein sodium from ophthalmic samples available commercially in the market. PMID:25736374

  4. Phase transfer of platinum nanoparticles from aqueous to organic solutions using fatty amine molecules

    Indian Academy of Sciences (India)

    Ashavani Kumar; Hrushikesh M Joshi; Anandrao B Mandale; Rajendra Srivastava; Suguna D Adyanthaya; Renu Pasricha; Murali Sastry

    2004-08-01

    In this report we demonstrate a simple process based on amine chemistry for the phase transfer of platinum nanoparticles from an aqueous to an organic solution. The phase transfer was accomplished by vigorous shaking of a biphasic mixture of platinum nanoparticles synthesised in an aqueous medium and octadecylamine (ODA) in hexane. During shaking of the biphasic mixture, the aqueous platinum nanoparticles complex via either coordination bond formation or weak covalent interaction with the ODA molecules present in the organic phase. This process renders the nanoparticles sufficiently hydrophobic and dispersible in the organic phase. The ODA-stabilised platinum nanoparticles could be separated out from hexane in the form of a powder that is readily redispersible in weakly polar and nonpolar organic solvents. The ODA-capped platinum nanoparticles show high catalytic activity in hydrogenation reactions and this is demonstrated in the efficient conversion of styrene to ethyl benzene. The nature of binding of the ODA molecules to the platinum nanoparticles surface was characterised by thermogravimetry, transmission electron microscopy (TEM), X-ray photoemission spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR).

  5. Aqueous preparation of polyethylene glycol/sulfonated graphene phase change composite with enhanced thermal performance

    International Nuclear Information System (INIS)

    Highlights: • We report an aqueous preparation technique of PEG/graphene phase change composite. • Hydrophilic sulfonated graphene (SG) nanosheets were synthesized. • Large increase in thermal conductivity is attained at low SG loading. • High latent heat is retained due to the low filler loading. • Affinity between SG and PEG contributes to the enhanced thermal performance. - Abstract: A polyethylene glycol (PEG)/sulfonated graphene (SG) phase change composite with enhanced thermal performance was prepared by solution processing in aqueous medium. It is remarkable that the addition of only 4 wt.% of SG to PEG could lead to a four times higher increase in thermal conductivity and a slight decrease in the phase change enthalpy, which is attributed to the formation of efficient thermal conductive network within the PEG matrix relevant to the excellent thermal property and unique 2-dimensional morphology of graphene as well as strong interface affinity between PEG matrix and SG nanosheets. The aqueous preparation technique is expected to pioneer a new way to prepare environment friendly organic phase change materials, and the production of PEG/SG composites is potentially scalable due to the facile fabricating process

  6. Towards a more detailed description of tropospheric aqueous phase organic chemistry: CAPRAM 3.0

    Science.gov (United States)

    Herrmann, H.; Tilgner, A.; Barzaghi, P.; Majdik, Z.; Gligorovski, S.; Poulain, L.; Monod, A.

    CAPRAM 3.0 is the latest development of the chemical aqueous phase radical mechanism (CAPRAM) series which is incorporating CAPRAM 2.4 (Ervens et al., 2003a, Journal of Geophysical Research—Atmospheres 108) and a new extended reaction mechanism for atmospherically relevant hydrocarbons containing more than two and up to six carbon atoms. The chemistry of organics containing three and four carbon atoms is now described in detail. Almost 400 new reactions are now implemented considering the chemistry of organic compounds containing different functional groups, i.e. alcohols, carbonyl compounds, mono- and dicarboxylic acids, polyfunctional compounds as well as some esters and one heterocyclic compound. The aqueous chemistry has been coupled to the gas phase mechanism RACM (regional atmospheric chemistry modeling) (Stockwell et al., 1997, Journal of Geophysical Research—Atmpspheres 102, 25847-25879), and phase exchange is treated using the resistance model of Schwartz (1986. In: Jaeschke, W. (Ed.), Chemistry of Multiphase Atmospheric Systems, NATO ASI Series, Springer, Berlin, pp. 415-471). The CAPRAM remote scenario which was chosen as the standard scenario showed that the introduction of the higher organic chemistry has a relevant influence on the standard subsystems. The diurnal peak concentration of OH radical in the droplets decreases with about 40% and the reactions of OH with hydrocarbons containing 3 or 4 carbon atoms account for about 10% out of the total sinks of OH in the droplets. A slightly stronger acidification of the aqueous phase in comparison to CAPRAM 2.4 is observed. The simulations for the standard scenario showed that there is an increase of organic mass within the droplets where the organic compounds containing 4 carbon atoms represent the 67.5% of the total mass, whereas in the urban and in the marine scenario the contribution of two carbon atom compounds is dominating. The formation and accumulation of substituted mono- and dicarboxylic

  7. Discovery of a tetracontinuous, aqueous lyotropic network phase with unusual 3D-hexagonal symmetry.

    Science.gov (United States)

    Sorenson, Gregory P; Schmitt, Adam K; Mahanthappa, Mahesh K

    2014-11-01

    Network phase aqueous lyotropic liquid crystals (LLCs) are technologically useful materials with myriad applications in chemistry, biology, and materials science, which stem from their structurally periodic aqueous and hydrophobic nanodomains (∼0.7-5.0 nm in diameter) that are lined with well-defined chemical functionalities. The exclusive observation of bicontinuous cubic network phase LLCs (e.g., double gyroid, double diamond, and primitive phases) has fueled speculations that all stable LLC network phases must exhibit cubic symmetry. Herein, we describe the self-assembly behavior of a simple aliphatic gemini surfactant that forms the first example of a triply periodic network phase LLC with the 3D-hexagonal symmetry P63/mcm (space group #193). This normal, tetracontinuous 3D-hexagonal network LLC phase HI(193) partitions space into four continuous and interpenetrating, yet non-intersecting volumes. This discovery directly demonstrates that the gemini amphiphile platform furnishes a rational strategy for discovering and stabilizing new, three-dimensionally periodic multiply continuous network phase LLCs with variable symmetries and potentially new applications. PMID:25182008

  8. Quality Measures in Pre-Analytical Phase of Tissue Processing: Understanding Its Value in Histopathology

    Science.gov (United States)

    Masilamani, Suresh; Sundaram, Sandhya; Duvuru, Prathiba; Swaminathan, Rajendiran

    2016-01-01

    Introduction Quality monitoring in histopathology unit is categorized into three phases, pre-analytical, analytical and post-analytical, to cover various steps in the entire test cycle. Review of literature on quality evaluation studies pertaining to histopathology revealed that earlier reports were mainly focused on analytical aspects with limited studies on assessment of pre-analytical phase. Pre-analytical phase encompasses several processing steps and handling of specimen/sample by multiple individuals, thus allowing enough scope for errors. Due to its critical nature and limited studies in the past to assess quality in pre-analytical phase, it deserves more attention. Aim This study was undertaken to analyse and assess the quality parameters in pre-analytical phase in a histopathology laboratory. Materials and Methods This was a retrospective study done on pre-analytical parameters in histopathology laboratory of a tertiary care centre on 18,626 tissue specimens received in 34 months. Registers and records were checked for efficiency and errors for pre-analytical quality variables: specimen identification, specimen in appropriate fixatives, lost specimens, daily internal quality control performance on staining, performance in inter-laboratory quality assessment program {External quality assurance program (EQAS)} and evaluation of internal non-conformities (NC) for other errors. Results The study revealed incorrect specimen labelling in 0.04%, 0.01% and 0.01% in 2007, 2008 and 2009 respectively. About 0.04%, 0.07% and 0.18% specimens were not sent in fixatives in 2007, 2008 and 2009 respectively. There was no incidence of specimen lost. A total of 113 non-conformities were identified out of which 92.9% belonged to the pre-analytical phase. The predominant NC (any deviation from normal standard which may generate an error and result in compromising with quality standards) identified was wrong labelling of slides. Performance in EQAS for pre-analytical phase was

  9. Aqueous phase partitioning of hexachlorocyclohexane (HCH) isomers by biosurfactant produced by Pseudomonas aeruginosa WH-2

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Suman; Singh, Partapbir [Department of Microbiology, Guru Nanak Dev University, Amritsar 143005, Punjab (India); Raj, Mayil [MTCC, IMTECH, Sector 39-A, Chandigarh 160036 (India); Chadha, Bhupinder Singh [Department of Microbiology, Guru Nanak Dev University, Amritsar 143005, Punjab (India); Saini, Harvinder Singh, E-mail: sainihs@yahoo.com [Department of Microbiology, Guru Nanak Dev University, Amritsar 143005, Punjab (India)

    2009-11-15

    The different isomers of technical-grade hexachlorocyclohexane (t-HCH) including the insecticidal {gamma}-isomer, commonly known as lindane, have been reported to be toxic, carcinogenic and endocrine disrupters. The spatial arrangements of the chlorine atoms on different isomers and low aqueous phase solubility contribute to their persistence in environment, {beta}-HCH being the most resistance to transformation. The biosurfactant preparation of Pseudomonas aeruginosa isolate WH-2 was evaluated for its ability to improve the aqueous phase partitioning of different isomers of HCH-muck. Further, the ability of biosurfactant preparation to emulsify HCH and n-hexadecane was checked under different conditions, usually characteristic of sites contaminated with pollutants viz. wide range of pH, temperature, and salinity. The data obtained from this study will be helpful in designing suitable bioremediation strategies for huge stock piles of HCH-muck and sites polluted by reckless use/disposal of HCH-isomers.

  10. Aqueous phase partitioning of hexachlorocyclohexane (HCH) isomers by biosurfactant produced by Pseudomonas aeruginosa WH-2

    International Nuclear Information System (INIS)

    The different isomers of technical-grade hexachlorocyclohexane (t-HCH) including the insecticidal γ-isomer, commonly known as lindane, have been reported to be toxic, carcinogenic and endocrine disrupters. The spatial arrangements of the chlorine atoms on different isomers and low aqueous phase solubility contribute to their persistence in environment, β-HCH being the most resistance to transformation. The biosurfactant preparation of Pseudomonas aeruginosa isolate WH-2 was evaluated for its ability to improve the aqueous phase partitioning of different isomers of HCH-muck. Further, the ability of biosurfactant preparation to emulsify HCH and n-hexadecane was checked under different conditions, usually characteristic of sites contaminated with pollutants viz. wide range of pH, temperature, and salinity. The data obtained from this study will be helpful in designing suitable bioremediation strategies for huge stock piles of HCH-muck and sites polluted by reckless use/disposal of HCH-isomers.

  11. Metallic and semiconducting carbon nanotubes separation using an aqueous two-phase separation technique: a review

    Science.gov (United States)

    Tang, Malcolm S. Y.; Ng, Eng-Poh; Juan, Joon Ching; Ooi, Chien Wei; Ling, Tau Chuan; Woon, Kai Lin; Loke Show, Pau

    2016-08-01

    It is known that carbon nanotubes show desirable physical and chemical properties with a wide array of potential applications. Nonetheless, their potential has been hampered by the difficulties in acquiring high purity, chiral-specific tubes. Considerable advancement has been made in terms of the purification of carbon nanotubes, for instance chemical oxidation, physical separation, and myriad combinations of physical and chemical methods. The aqueous two-phase separation technique has recently been demonstrated to be able to sort carbon nanotubes based on their chirality. The technique requires low cost polymers and salt, and is able to sort the tubes based on their diameter as well as metallicity. In this review, we aim to provide a review that could stimulate innovative thought on the progress of a carbon nanotubes sorting method using the aqueous two-phase separation method, and present possible future work and an outlook that could enhance the methodology.

  12. Large-scale synthesis of CdTe quantum dots in aqueous phase

    International Nuclear Information System (INIS)

    In this paper, we present the systematically experimental results on the influence of pH of the reaction medium, molar ratio of the precursors on the synthesis in aqueous phase of CdTe quantum dots (QDs) and CdTe/CdS QDs with core/shell structure. Under optimal synthesis conditions, water-soluble CdTe and CdTe/CdS QDs has been prepared that exhibit very strong photoluminescence peaking in the spectral range between 520 nm and 650 nm with narrow full width at half maximum (∼ 32 nm in the short-wavelength emission case); depending on the emission range, most samples however exhibit the high luminescence quantum yields (∼ 40%). Moreover, the synthesis in aqueous phase shows some additional advantages: it is possible to prepare high quality CdTe QDs in large-scale (up to gram/reaction) with low cost, less toxic and short production time. (author)

  13. Heterogeneous Catalytic Conversion of Biobased Chemicals into Liquid Fuels in the Aqueous Phase.

    Science.gov (United States)

    Wu, Kejing; Wu, Yulong; Chen, Yu; Chen, Hao; Wang, Jianlong; Yang, Mingde

    2016-06-22

    Different biobased chemicals are produced during the conversion of biomass into fuels through various feasible technologies (e.g., hydrolysis, hydrothermal liquefaction, and pyrolysis). The challenge of transforming these biobased chemicals with high hydrophilicity is ascribed to the high water content of the feedstock and the inevitable formation of water. Therefore, aqueous-phase processing is an interesting technology for the heterogeneous catalytic conversion of biobased chemicals. Different reactions, such as dehydration, isomerization, aldol condensation, ketonization, and hydrogenation, are applied for the conversion of sugars, furfural/hydroxymethylfurfural, acids, phenolics, and so on over heterogeneous catalysts. The activity, stability, and reusability of the heterogeneous catalysts in water are summarized, and deactivation processes and several strategies are introduced to improve the stability of heterogeneous catalysts in the aqueous phase. PMID:27158985

  14. Multi-analyte approach for the determination of ng.l-1 amounts of steroid hormones in unidentified aqueous samples

    OpenAIRE

    Noppe, H.; VERHEYDEN, K; Gillis, W.; Courtheyn, D.; Vanthemsche, P.; De Brabander, H.F.

    2006-01-01

    Since the 70s, many analytical methods for the detection of illegal growth promotors, such as thyreostats, anabolics, ß-agonists and corticosteroids have been developed for a wide range of matrices of animal origin, including meat, fat, organ tissue, urine and faeces. The aim of this study was to develop an analytical method for the determination of ng.l-1 levels of estrogens, gestagens, androgens (EGAs) and corticosteroids in aqueous preparations (i.e. drinking water, drinking water suppleme...

  15. Partitioning Behavior of Papain in Ionic Liquids-Based Aqueous Two-Phase Systems

    OpenAIRE

    Zhiwen Bai; Yanhong Chao; Meiling Zhang; Changri Han; Wenshuai Zhu; Yonghui Chang; Huaming Li; Yang Sun

    2013-01-01

    This paper attempts to study and optimize the affinity partitioning conditions of papain in an aqueous two-phase system (ATPS). The effect of the amount of ionic liquids (ILs), the concentration of K2HPO4, temperature, pH, and the volume of papain solution were discussed concretely. The optimum conditions were determined as ionic liquid was 1.4 g and K2HPO4 was 1.4 g, the extraction efficiency of papain co...

  16. Ultradry Carbon Dioxide-in-Water Foams with Viscoelastic Aqueous Phases.

    Science.gov (United States)

    Xue, Zheng; Worthen, Andrew J; Da, Chang; Qajar, Ali; Ketchum, Isaiah Robert; Alzobaidi, Shehab; Huh, Chun; Prodanović, Maša; Johnston, Keith P

    2016-01-12

    For foams with ultra low water contents, the capillary pressure is very large and induces rapid drainage that destabilizes the aqueous lamellae between the gas bubbles. However, we show that high-pressure CO2-in-water foams can be stabilized with a viscoelastic aqueous phase composed of entangled wormlike micelles, even for extremely high CO2 volume fractions ϕ of 0.95 to 0.98; the viscosity of these ultradry foams increased by up to 3-4-fold, reaching more than 100 cP relative to foams formed with conventional low viscosity aqueous phases. The foam morphology consisted of fine ∼20 μm polyhedral-shaped CO2 bubbles that were stable for hours. The wormlike micelles were formed by mixing anionic sodium lauryl ether sulfate (SLES) with salt and a protonated cationic surfactant, as shown by cryogenic transmission electron microscopy (cryo-TEM) and large values of the zero-shear viscosity and the dynamic storage and loss moduli. With the highly viscous continuous aqueous phases, the foam lamella drainage rates were low, as corroborated by confocal microscopy. The preservation of viscous thick lamellae resulted in lower rates of Ostwald ripening relative to conventional foams as shown by high-pressure optical microscopy. The ability to stabilize viscous ultra high internal phase foams is expected to find utility in various practical applications, including nearly "waterless" fracturing fluids for recovery of oil and gas in shale, offering the possibility of a massive reduction in the amount of wastewater. PMID:26666311

  17. Temperature-induced phase transition in aqueous solutions and gels of multicomponent polymer systems

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Konefal, Rafal; Dybal, Jiří

    Kolkata : Indian Association for the Cultivation of Science, 2016. s. 48-49. [International IUPAC Conference on Polymer -Solvent Complexes and Intercalates /11./ - POLYSOLVAT-11. 27.01.2016-30.01.2016, Kolkata] R&D Projects: GA ČR(CZ) GA15-13853S Institutional support: RVO:61389013 Keywords : temperature-induced phase transition * aqueous solution * hydrogel Subject RIV: CD - Macromolecular Chemistry

  18. A Novel Approach for Microencapsulation of Nanoemulsions to Overcome the Oxidation of Bioactives in Aqueous Phase

    OpenAIRE

    Haroon Jamshaid Qazi; Hamid Majeed; Waseem Safdar; John Antoniou; Zhong Fang

    2015-01-01

    Microencapsulation is a promising technique to retain the physical attributes of nanoemulsions and to overcome the oxidation of bioactives that become more available to aqueous phase during emulsification. Purity Gum Ultra (PGU) and Hi-CAP 100 (HiCap) emulsified nanoemulsions of Clove Oil (CO) co-encapsulated with Canola oil (CA) and Medium Chain Triglyceride (MCT) (5:5% v/v CO:CA and CO:MCT) were prepared through high pressure homogenization. Microencapsulation of nanoemulsions was performed...

  19. Ruthenium on rutile catalyst, catalytic system, and method for aqueous phase hydrogenations

    Science.gov (United States)

    Elliot, Douglas C.; Werpy, Todd A.; Wang, Yong; Frye, Jr., John G.

    2001-01-01

    An essentially nickel- and rhenium-free catalyst is described comprising ruthenium on a titania support where the titania is greater than 75% rutile. A catalytic system containing a nickel-free catalyst comprising ruthenium on a titania support where the titania is greater than 75% rutile, and a method using this catalyst in the hydrogenation of an organic compound in the aqueous phase is also described.

  20. REMOVAL OF METHYLENE BLUE FROM AQUEOUS PHASE BY PRETREATED WALNUT SHELL IN A PACKED COLUMN

    OpenAIRE

    A.A. Nazari-Moghaddam; Najafpour, G.D.; A.A. Ghoeyshi; M Mohammadi; harif Hussein Sharif Zein

    2010-01-01

    Methylene blue (MB) adsorption from aqueous phase was investigated. Pretreated walnut shell, as adsorbent was used. Experiments were conducted in a batch system for determination of sorption equilibria and then the data were incorporated in a packed column for the removal of MB from synthetic wastewater. The generated wastewater was contained 4 mg/l of MB. The wastewater was pumped through the column with flow rate of 18 ml/min and the effluent samples were collected. The effect of influent M...

  1. Two-phase bounded acceleration traffic flow model: Analytical solutions and applications

    OpenAIRE

    LEBACQUE, JP

    2003-01-01

    The present paper describes a two phase traffic flow model. One phase is traffic equilibrium: flow and speed are functions of density, and traffic acceleration is low. The second phase is characterized by constant acceleration. This model extends first order traffic flow models and recaptures the fact that traffic acceleration is bounded. The paper show how to calculate analytical solutions of the two-phase model for dynamic traffic situations, provides a set of calculation rules, and analyze...

  2. Equivalent aqueous phase modulation of domain segregation in myelin monolayers and bilayer vesicles

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, R.G. [Universidad Nacional de Cordoba, Cordoba, CO (Argentina)

    2012-07-01

    Full text: Purified myelin can be spread as monomolecular films at the air/aqueous interface. These films were visualized by fluorescence and Brewster angle microscopy, showing phase coexistence at low and medium surface pressures (<20-30 mN/m). Beyond this threshold, the film becomes homogeneous or not, depending on the aqueous sub phase composition. Pure water as well as sucrose, glycerol, dimethylsulfoxide, and dimethylformamide solutions (20% in water) produced monolayers that become homogeneous at high surface pressures; on the other hand, the presence of salts (NaCl, CaCl{sub 2}) in Ringers and physiological solution leads to phase domain microheterogeneity over the whole compression isotherm. These results show that surface heterogeneity is favored by the ionic milieu. The modulation of the phase-mixing behavior in monolayers is paralleled by the behavior of multilamellar vesicles as determined by small-angle and wide-angle x-ray scattering. The correspondence of the behavior of monolayers and multilayers is achieved only at high surface pressures near the equilibrium adsorption surface pressure; at lower surface pressures, the correspondence breaks down. The equilibrium surface tension on all sub phases corresponds to that of the air/alkane interface (27 mN/m), independently on the surface tension of the clean sub phase. (author)

  3. Carbon Mineralization by Aqueous Precipitation for Beneficial Use of CO2 from Flue Gas. Phase I. Final Topical Report

    International Nuclear Information System (INIS)

    Calera's innovative Mineralization via Aqueous Precipitation (MAP) technology for the capture and conversion of CO2 to useful materials for use in the built environment was further developed and proven in the Phase 1 Department of Energy Grant. The process was scaled to 300 gallon batch reactors and subsequently to Pilot Plant scale for the continuous production of product with the production of reactive calcium carbonate material that was evaluated as a supplementary cementitious material (SCM). The Calera SCM(trademark) was evaluated as a 20% replacement for ordinary portland cement and demonstrated to meet the industry specification ASTM 1157 which is a standard performance specification for hydraulic cement. The performance of the 20% replacement material was comparable to the 100% ordinary portland cement control in terms of compressive strength and workability as measured by a variety of ASTM standard tests. In addition to the performance metrics, detailed characterization of the Calera SCM was performed using advanced analytical techniques to better understand the material interaction with the phases of ordinary portland cement. X-ray synchrotron diffraction studies at the Advanced Photon Source in Argonne National Lab confirmed the presence of an amorphous phase(s) in addition to the crystalline calcium carbonate phases in the reactive carbonate material. The presence of carboaluminate phases as a result of the interaction of the reactive carbonate materials with ordinary portland cement was also confirmed. A Life Cycle Assessment was completed for several cases based on different Calera process configurations and compared against the life cycle of ordinary portland cement. In addition to the materials development efforts, the Calera technology for the production of product using an innovative building materials demonstration plant was developed beyond conceptual engineering to a detailed design with a construction schedule and cost estimate.

  4. Purification of plasmid DNA vectors by aqueous two-phase extraction and hydrophobic interaction chromatography

    OpenAIRE

    Trindade, Inês P.; Diogo, Maria M.; Prazeres, Duarte M. F.; Marcos, João Carlos

    2005-01-01

    The current study explores the possibility of using a polyethyleneglycol(PEG)/ammonium sulphate aqueous two-phase system (ATPS) as an early step in a process for the purification of a model 6.1 kbp plasmid DNA (pDNA) vector. Neutralised alkaline lysates were fed directly to ATPS. Conditions were selected to direct pDNA towards the salt-rich bottom phase, so that this stream could be subsequently processed by hydrophobic interaction chromatography (HIC). Screening of the best conditions for AT...

  5. Comparison of colorimetric methods for the quantification of model proteins in aqueous two-phase systems.

    Science.gov (United States)

    Glyk, Anna; Heinisch, Sandra L; Scheper, Thomas; Beutel, Sascha

    2015-05-15

    In the current study, the quantification of different model proteins in the presence of typical aqueous two-phase system components was investigated by using the Bradford and bicinchoninic acid (BCA) assays. Each phase-forming component above 1 and 5 wt% had considerable effects on the protein quantification in both assays, respectively, resulting in diminished protein recoveries/absorption values by increasing poly(ethylene glycol) (PEG)/salt concentration and PEG molecular weight. Therefore, a convenient dilution of both components (up to 1 and 5 wt%) before protein quantification is recommended in both assays, respectively, where the BCA assay is favored in comparison with the Bradford assay. PMID:25684109

  6. Purification and In Situ Immobilization of Papain with Aqueous Two-Phase System

    OpenAIRE

    Li, Mingliang; Su, Erzheng; You, Pengyong; Gong, Xiangyu; Sun, Ming; Xu, Diansheng; Wei, Dongzhi

    2010-01-01

    Papain was purified from spray-dried Carica papaya latex using aqueous two-phase system (ATPS). Then it was recovered from PEG phase by in situ immobilization or preparing cross-linked enzyme aggregates (CLEAs). The Plackett-Burman design and the central composite design (CCD) together with the response surface methodology (RSM) were used to optimize the APTS processes. The highly purified papain (96–100%) was achieved under the optimized conditions: 40% (w/w) 15 mg/ml enzyme solution, 14.33–...

  7. Purification of Active Myrosinase from Plants by Aqueous Two-Phase Counter-Current Chromatography

    Science.gov (United States)

    Wade, Kristina L.; Ito, Yoichiro; Ramarathnam, Aarthi; Holtzclaw, W. David; Fahey, Jed W.

    2014-01-01

    Introduction Myrosinase (thioglucoside glucohydrolase; E.C. 3.2.1.147), is a plant enzyme of increasing interest and importance to the biomedical community. Myrosinase catalyses the formation of isothiocyanates such as sulforaphane (frombroccoli) and 4-(α-l-rhamnopyranosyloxy)benzyl isothiocyanate (from moringa), which are potent inducers of the cytoprotective phase-2 response in humans, by hydrolysis of their abundant glucosinolate (β-thioglucoside N-hydroxysulphate) precursors. Objective To develop an aqueous two-phase counter-current chromatography (CCC) system for the rapid, three-step purification of catalytically active myrosinase. Methods A high-concentration potassium phosphate and polyethylene glycol biphasic aqueous two-phase system (ATPS) is used with a newly developed CCC configuration that utilises spiral-wound, flat-twisted tubing (with an ovoid cross-section). Results Making the initial crude plant extract directly in the ATPS and injecting only the lower phase permitted highly selective partitioning of the myrosinase complex before a short chromatography on a spiral disk CCC. Optimum phase retention and separation of myrosinase from other plant proteins afforded a 60-fold purification. Conclusion Catalytically active myrosinase is purified from 3-day broccoli sprouts, 7-day daikon sprouts, mustard seeds and the leaves of field-grown moringa trees, in a CCC system that is predictably scalable. PMID:25130502

  8. Low-temperature aqueous-phase reforming of ethanol on bimetallic PdZn catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Haifeng; DelaRiva, Andrew; Wang, Yong; Dayte, Abhaya

    2015-01-01

    Bimetallic PdZn catalysts supported on carbon black (CB) and carbon nanotubes (CNTs) were found to be selective for CO-free H-2 production from ethanol at low temperature (250 degrees C). On Pd, the H-2 yield was low (similar to 0.3 mol H-2/mol ethanol reacted) and the CH4/CO2 ratio was high (similar to 1.7). Addition of Zn to Pd formed the intermetallic PdZn beta phase (atomic ratio of Zn to Pd is 1) with increased H-2 yield (similar to 1.9 mol H-2/mol ethanol reacted) and CH4/CO2 ratio of <1. The higher H-2 yield and low CH4 formation was related to the improved dehydrogenation activity of the L1(0) PdZn beta phase. The TOF increased with particle size and the CNTs provided the most active and selective catalysts, which may be ascribed to pore-confinement effects. Furthermore, no significant changes in either the supports or the PdZn beta particles was found after aqueous-phase reforming (APR) indicating that the metal nanoparticles and the carbon support are hydrothermally stable in the aqueous phase at elevated temperatures and pressures (>200 degrees C, 65 bar). No CO was detected for all the catalysts performed in aqueous-phase reaction, indicating that both monometallic Pd and bimetallic PdZn catalysts have high water-gas shift activity during APR. However, the yield of H-2 is considerably lower than the theoretical value of 6 H-2 per mole ethanol which is due to the presence of oxygenated products and methane on the PdZn catalysts.

  9. Numerical Verification of an Analytical Model for Phase Noise in MEMS Oscillators.

    Science.gov (United States)

    Agrawal, D K; Bizzarri, F; Brambilla, A; Seshia, A A

    2016-08-01

    A new analytical formulation for phase noise in MEMS oscillators was recently presented encompassing the role of essential nonlinearities in the electrical and mechanical domains. In this paper, we validate the effectiveness of the proposed analytical formulation with respect to the unified theory developed by Demir et al. describing phase noise in oscillators. In particular, it is shown that, over a range of the second-order mechanical nonlinear stiffness of the MEMS resonator, both models exhibit an excellent match in the phase diffusion coefficient calculation for a square-wave MEMS oscillator. PMID:27295660

  10. On the form invariant volume transformation in phase space by focusing neutron guides: An analytic treatment

    Energy Technology Data Exchange (ETDEWEB)

    Stüßer, N., E-mail: stuesser@helmholtz-berlin.de; Hofmann, T., E-mail: tommy.hofmann@helmholtz-berlin.de

    2013-11-01

    Tapered guides with supermirror coating are frequently used to focus neutron beams on specimens. The divergence distribution in the focused beam is of a great importance for the quality of neutron instrumentation. Using an analytic approach we derive the tapering which is needed to achieve a form invariant phase space transformation of a rectangular phase volume. In addition we consider the effect of beam attenuation by the finite reflectivity of supermirrors. -- Highlights: • Form invariant volume transformation in phase space. • Focusing modules for neutron beams. • Analytical approach. • Attenuation effects in linearly and nonlinearly tapered guides.

  11. Evaluation of the Component Chemical Potentials in Analytical Models for Ordered Alloy Phases

    Directory of Open Access Journals (Sweden)

    W. A. Oates

    2011-01-01

    Full Text Available The component chemical potentials in models of solution phases with a fixed number of sites can be evaluated easily when the Helmholtz energy is known as an analytical function of composition. In the case of ordered phases, however, the situation is less straightforward, because the Helmholtz energy is a functional involving internal order parameters. Because of this, the chemical potentials are usually obtained numerically from the calculated integral Helmholtz energy. In this paper, we show how the component chemical potentials can be obtained analytically in ordered phases via the use of virtual cluster chemical potentials. Some examples are given which illustrate the simplicity of the method.

  12. Distribution of selected halogenated organic compounds among suspended particulate, colloid, and aqueous phases in the Mississippi River and major tributaries

    Science.gov (United States)

    Rostad, C.E.; Daniel, S.R.

    2007-01-01

    Suspended particulate, colloid, and aqueous phases were separated and analyzed to determine spatial variation of specific organic compound transport associated with each phase in a dynamic river system. Sixteen sites along the Mississippi River and its major tributaries were sampled at low-flow conditions to maximize the possibility of equilibrium. Across the solubility range studied, the proportion transported by each phase depended on the compound solubility, with more water-soluble compounds (dacthal, trifluralin) transported predominantly in the aqueous phase and less-water soluble compounds (polychlorinated biphenyls, chlordane-related compounds) transported predominantly in the particulate and colloid phases. ?? 2007 Springer Science+Business Media, LLC.

  13. Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets

    Science.gov (United States)

    Hoyle, C. R.; Fuchs, C.; Järvinen, E.; Saathoff, H.; Dias, A.; El Haddad, I.; Gysel, M.; Coburn, S. C.; Tröstl, J.; Bernhammer, A.-K.; Bianchi, F.; Breitenlechner, M.; Corbin, J. C.; Craven, J.; Donahue, N. M.; Duplissy, J.; Ehrhart, S.; Frege, C.; Gordon, H.; Höppel, N.; Heinritzi, M.; Kristensen, T. B.; Molteni, U.; Nichman, L.; Pinterich, T.; Prévôt, A. S. H.; Simon, M.; Slowik, J. G.; Steiner, G.; Tomé, A.; Vogel, A. L.; Volkamer, R.; Wagner, A. C.; Wagner, R.; Wexler, A. S.; Williamson, C.; Winkler, P. M.; Yan, C.; Amorim, A.; Dommen, J.; Curtius, J.; Gallagher, M. W.; Flagan, R. C.; Hansel, A.; Kirkby, J.; Kulmala, M.; Möhler, O.; Stratmann, F.; Worsnop, D. R.; Baltensperger, U.

    2016-02-01

    The growth of aerosol due to the aqueous phase oxidation of sulfur dioxide by ozone was measured in laboratory-generated clouds created in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN). Experiments were performed at 10 and -10 °C, on acidic (sulfuric acid) and on partially to fully neutralised (ammonium sulfate) seed aerosol. Clouds were generated by performing an adiabatic expansion - pressurising the chamber to 220 hPa above atmospheric pressure, and then rapidly releasing the excess pressure, resulting in a cooling, condensation of water on the aerosol and a cloud lifetime of approximately 6 min. A model was developed to compare the observed aerosol growth with that predicted using oxidation rate constants previously measured in bulk solutions. The model captured the measured aerosol growth very well for experiments performed at 10 and -10 °C, indicating that, in contrast to some previous studies, the oxidation rates of SO2 in a dispersed aqueous system can be well represented by using accepted rate constants, based on bulk measurements. To the best of our knowledge, these are the first laboratory-based measurements of aqueous phase oxidation in a dispersed, super-cooled population of droplets. The measurements are therefore important in confirming that the extrapolation of currently accepted reaction rate constants to temperatures below 0 °C is correct.

  14. Phase Diagrams of the Aqueous Two-Phase Systems of Poly(ethylene glycol/Sodium Polyacrylate/Salts

    Directory of Open Access Journals (Sweden)

    Adalberto Pessoa Junior

    2011-03-01

    Full Text Available Aqueous two-phase systems consisting of polyethylene glycol (PEG, sodium polyacrylate (NaPAA, and a salt have been studied. The effects of the polymer size, salt type (NaCl, Na2SO4, sodium adipate and sodium azelate and salt concentrations on the position of the binodal curve were investigated. The investigated PEG molecules had a molar mass of 2,000 to 8,000 g/mol, while that of NaPAA was 8,000 g/mol. Experimental phase diagrams, and tie lines and calculated phase diagrams, based on Flory-Huggins theory of polymer solutions are presented. Due to strong enthalpic and entropic balancing forces, the hydrophobicity of the added salt has a strong influence on the position of the binodal, which could be reproduced by model calculations.

  15. Hydro fuel is produce through aqueous-phase reforming process by using glycerol as by-product from oil palms

    International Nuclear Information System (INIS)

    Full text: The research is aim to study the type of catalysts (e.g. Pt-Ni, Pt and Ni catalysts) that are use to increase the yield of hydrogen gas in the reaction of aqueous-phase reforming (APR) process ,that use glycerol to produce hydrogen gas using steam. The output product of aqueous-phase reforming (APR) process are hydrogen, carbon monoxide and carbon dioxide gases. (author)

  16. Analytic Study of First-Order Phase Transition in Holographic Superconductor and Superfluid

    OpenAIRE

    Huang, Wung-Hong

    2013-01-01

    We use the matching method to investigate the first-order phase transition in holographic superconductor and superfluid. We first use the simple holographic superconductor model to describe the matching method and mention how to see the first-order phase transition. Next, we study the holographic superconductor with St\\"uckelberg term and see that the analytic results indicate the existence of first-order phase transition. Finally, we study the holographic superfluid and show that the first-o...

  17. Thermodynamic modelling of phase equilibrium for water + poly(Ethylene glycol + salt aqueous two-phase systems

    Directory of Open Access Journals (Sweden)

    R.A.G. Sé

    2002-04-01

    Full Text Available The NRTL (nonrandom, two-liquid model, expressed in mass fraction instead of mole fraction, was used to correlate liquid-liquid equilibria for aqueous two-phase polymer-salt solutions. New interaction energy parameters for this model were determined using reported data on the water + poly(ethylene glycol + salt systems, with different molecular masses for PEG and the salts potassium phosphate, sodium sulfate, sodium carbonate and magnesium sulfate. The correlation of liquid-liquid equilibrium is quite satisfactory.

  18. Characterization of aqueous two phase systems by combining lab-on-a-chip technology with robotic liquid handling stations.

    Science.gov (United States)

    Amrhein, Sven; Schwab, Marie-Luise; Hoffmann, Marc; Hubbuch, Jürgen

    2014-11-01

    Over the last decade, the use of design of experiment approaches in combination with fully automated high throughput (HTP) compatible screenings supported by robotic liquid handling stations (LHS), adequate fast analytics and data processing has been developed in the biopharmaceutical industry into a strategy of high throughput process development (HTPD) resulting in lower experimental effort, sample reduction and an overall higher degree of process optimization. Apart from HTP technologies, lab-on-a-chip technology has experienced an enormous growth in the last years and allows further reduction of sample consumption. A combination of LHS and lab-on-a-chip technology is highly desirable and realized in the present work to characterize aqueous two phase systems with respect to tie lines. In particular, a new high throughput compatible approach for the characterization of aqueous two phase systems regarding tie lines by exploiting differences in phase densities is presented. Densities were measured by a standalone micro fluidic liquid density sensor, which was integrated into a liquid handling station by means of a developed generic Tip2World interface. This combination of liquid handling stations and lab-on-a-chip technology enables fast, fully automated, and highly accurate density measurements. The presented approach was used to determine the phase diagram of ATPSs composed of potassium phosphate (pH 7) and polyethylene glycol (PEG) with a molecular weight of 300, 400, 600 and 1000 Da respectively in the presence and in the absence of 3% (w/w) sodium chloride. Considering the whole ATPS characterization process, two complete ATPSs could be characterized within 24h, including four runs per ATPS for binodal curve determination (less than 45 min/run), and tie line determination (less than 45 min/run for ATPS preparation and 8h for density determination), which can be performed fully automated over night without requiring man power. The presented methodology provides

  19. A stable liquid–liquid extraction system for clavulanic acid using polymer-based aqueous two-phase systems

    OpenAIRE

    Pereira, Jorge F. B.; Santos, Valéria Carvalho; Johansson, Hans-Olof; J. A. Teixeira; Pessoa Júnior, Adalberto

    2012-01-01

    The partitioning of Clavulanic Acid (CA) in a novel inexpensive and stable aqueous two-phase system (ATPS) composed by poly(ethylene glycol) (PEG) and sodium polyacrylate (NaPA) has been studied. The aqueous two-phase systems are formed by mixing both polymers with a salt (NaCl or Na2SO4) and an aqueous solution of CA. The stability of CA on the presence of both polymers was investigated and it was observed that these polymers do not degrade the biomolecule. The effect of PEG-molecular ...

  20. The Effect of pH Difference Between Two Phases on the Partition of Lysozyme in Aqueous Two-Phase System

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the investigation of effect of KSCN on the partitioning of lysozyme in PEG2000/ammonium sulfate aqueous two-phase system, it was found that the KSCN could alter the pH difference between the two phases, and thus affect the partition of lysozyme. The relationship between partition coefficients of lysozyme and pH differences between two phases was discussed.

  1. Selective separation and enrichment of proteins in aqueous two-phase extraction system

    Institute of Scientific and Technical Information of China (English)

    Feng Qu; Hao Qin; Min Dong; Dong Xu Zhao; Xin Ying Zhao; Jing Hua Zhang

    2009-01-01

    A simple aqueous two-phase extraction system(ATPS)of PEG/phosphate was proposed for selective separation and enrichment of proteins.The combination of ATPE with HPLC was applied to identify the partition of proteins in two phases.Five proteins (bovine serum albumin,Cytochrome C,lysozyme,myoglobin,and trypsin)were used as model proteins to study the effect of phosphate concentration and pH on proteins partition.The PEG/phosphate system was firstly applied to real human saliva and plasma samples,some proteins showed obviously different partition in two phases.The primary results manifest the selective separation and enrichment of proteins in ATPS provided the potential for high abundance proteins depletion in proteomics.

  2. NMR signal analysis to characterize solid, aqueous, and lipid phases in baked cakes.

    Science.gov (United States)

    Le Grand, F; Cambert, M; Mariette, F

    2007-12-26

    Proton mobility was studied in molecular fractions of some model systems and of cake using a 1H nuclear magnetic resonance (NMR) relaxation technique. For cake, five spin-spin relaxation times (T2) were obtained from transverse relaxation curves: T2 (1) approximately 20 micros, T2 (2) approximately 0.2 ms, T2 (3) approximately 3 ms, T2 (4) approximately 50 ms, and T2 (2) approximately 165 ms. The faster component was attributed to the solid phase, components 2 and 3 were associated with the aqueous phase, and the two slowest components were linked to the lipid phase. After cooking, the crust contained more fat but less water than the center part of the cake. The amount of gelatinized starch was lower in the crust, and water was more mobile due to less interaction with macromolecules. This preliminary study revealed different effects of storage on the center and crust. PMID:18044835

  3. Rapid RNA Exchange in Aqueous Two-Phase System and Coacervate Droplets

    Science.gov (United States)

    Jia, Tony Z.; Hentrich, Christian; Szostak, Jack W.

    2014-02-01

    Compartmentalization in a prebiotic setting is an important aspect of early cell formation and is crucial for the development of an artificial protocell system that effectively couples genotype and phenotype. Aqueous two-phase systems (ATPSs) and complex coacervates are phase separation phenomena that lead to the selective partitioning of biomolecules and have recently been proposed as membrane-free protocell models. We show in this study through fluorescence recovery after photobleaching (FRAP) microscopy that despite the ability of such systems to effectively concentrate RNA, there is a high rate of RNA exchange between phases in dextran/polyethylene glycol ATPS and ATP/poly-L-lysine coacervate droplets. In contrast to fatty acid vesicles, these systems would not allow effective segregation and consequent evolution of RNA, thus rendering these systems ineffective as model protocells.

  4. Protein partitioning in poly(ethylene glycol)/sodium polyacrylate aqueous two-phase systems.

    Science.gov (United States)

    Johansson, Hans-Olof; Magaldi, Flavio Musa; Feitosa, Eloi; Pessoa, Adalberto

    2008-01-18

    The partition of hemoglobin, lysozyme and glucose-6-phosphate dehydrogenase (G6PDH) in a novel inexpensive aqueous two-phase system (ATPS) composed by poly(ethylene glycol) (PEG) and sodium polyacrylate (NaPA) has been studied. The effect of NaCl and Na(2)SO(4), pH and PEG molecular size on the partitioning has been studied. At high pH (above 9), hemoglobin partitions strongly to the PEG-phase. Although some precipitation of hemoglobin occurs, high recovery values are obtained particularly for lysozyme and G6PDH. The partitioning forces are dominated by the hydrophobic and electrochemical (salt) effects, since the positively charged lysozyme and negatively charged G6PDH partitions to the non-charged PEG and the strongly negatively charged polyacrylate enriched phase, respectively. PMID:18078945

  5. Phase field modelling of stressed grain growth: Analytical study and the effect of microstructural length scale

    Energy Technology Data Exchange (ETDEWEB)

    Jamshidian, M., E-mail: mostafa.jamshidian@gmail.com [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Institute of Structural Mechanics, Bauhaus-University Weimar, Marienstrasse 15, 99423 Weimar (Germany); Rabczuk, T., E-mail: timon.rabczuk@uni-weimar.de [Institute of Structural Mechanics, Bauhaus-University Weimar, Marienstrasse 15, 99423 Weimar (Germany); School of Civil, Environmental and Architectural Engineering, Korea University, Seoul (Korea, Republic of)

    2014-03-15

    We establish the correlation between the diffuse interface and sharp interface descriptions for stressed grain boundary migration by presenting analytical solutions for stressed migration of a circular grain boundary in a bicrystalline phase field domain. The validity and accuracy of the phase field model is investigated by comparing the phase field simulation results against analytical solutions. The phase field model can reproduce precise boundary kinetics and stress evolution provided that a thermodynamically consistent theory and proper expressions for model parameters in terms of physical material properties are employed. Quantitative phase field simulations are then employed to investigate the effect of microstructural length scale on microstructure and texture evolution by stressed grain growth in an elastically deformed polycrystalline aggregate. The simulation results reveal a transitional behaviour from normal to abnormal grain growth by increasing the microstructural length scale.

  6. Phase field modelling of stressed grain growth: Analytical study and the effect of microstructural length scale

    International Nuclear Information System (INIS)

    We establish the correlation between the diffuse interface and sharp interface descriptions for stressed grain boundary migration by presenting analytical solutions for stressed migration of a circular grain boundary in a bicrystalline phase field domain. The validity and accuracy of the phase field model is investigated by comparing the phase field simulation results against analytical solutions. The phase field model can reproduce precise boundary kinetics and stress evolution provided that a thermodynamically consistent theory and proper expressions for model parameters in terms of physical material properties are employed. Quantitative phase field simulations are then employed to investigate the effect of microstructural length scale on microstructure and texture evolution by stressed grain growth in an elastically deformed polycrystalline aggregate. The simulation results reveal a transitional behaviour from normal to abnormal grain growth by increasing the microstructural length scale

  7. Analytical calculation of spectral phase of grism pairs by the geometrical ray tracing method

    Science.gov (United States)

    Rahimi, L.; Askari, A. A.; Saghafifar, H.

    2016-07-01

    The most optimum operation of a grism pair is practically approachable when an analytical expression of its spectral phase is in hand. In this paper, we have employed the accurate geometrical ray tracing method to calculate the analytical phase shift of a grism pair, at transmission and reflection configurations. As shown by the results, for a great variety of complicated configurations, the spectral phase of a grism pair is in the same form of that of a prism pair. The only exception is when the light enters into and exits from different facets of a reflection grism. The analytical result has been used to calculate the second-order dispersions of several examples of grism pairs in various possible configurations. All results are in complete agreement with those from ray tracing method. The result of this work can be very helpful in the optimal design and application of grism pairs at various configurations.

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

    Science.gov (United States)

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

    2011-07-22

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

  9. Mapping the Complex Phase Behaviors of Aqueous Mixtures of κ-Carrageenan and Type B Gelatin.

    Science.gov (United States)

    Cao, Yiping; Wang, Lu; Zhang, Ke; Fang, Yapeng; Nishinari, Katsuyoshi; Phillips, Glyn O

    2015-07-30

    We report a detailed and complete phase diagram for an aqueous mixture of oppositely charged gelling biopolymers, type B gelatin and κ-carrageenan (KC) at pH 7.0. The phase diagram is studied in the ionic strength-temperature coordinate by means of turbidity, rheological and differential scanning calorimetric measurements, and macroscopic phase compositional analysis. Seven phase regions are identified, including (I) compatible region, (II) electrostatically induced associative phase separation (EIAPS) region, (III) hydrogen bonding induced associative phase separation (HBIAPS) region, (IV) coexistence of EIAPS and HBIAPS, (V) segregative phase separation (SPS) region, (VI) coexistence of HBIAPS and SPS, and (VII) SPS trapped by gelation. The HBIAPS reported for the first time here is attributed to the extensive hydrogen bonding formation between gelatin and KC above their conformational transition temperatures, as probed by addition of urea and methylene blue as well as by 2D (1)H-(1)H NOESY NMR. NaCl is found to have dual effects on HBIAPS. The electrostatic complexation at lower ionic strength facilitates the formation of hydrogen bonds between gelatin and KC and hence the HBIAPS. It is believed that the local structural arrangement of gelatin molecules or the change in local solvent environment prior to triple helix formation during cooling enables the formation of hydrogen bonds with KC. PMID:26147592

  10. The phase transport and reactions of γ-irradiated aqueous-ionic liquids

    International Nuclear Information System (INIS)

    A novel technology based on the transfer of chemical species across water/ionic liquid interfaces via specific complexation reactions is currently being considered for the separation and sequestration of metal ion contaminants from radioactive waste effluents in the nuclear fuel cycle. An ideal solvent for these applications should have a high intrinsic selectivity for a targeted metal or group of metals (e.g., trans-Pu actinides, lanthanides, or other fission products), an efficient switching mechanism (between complexation and decomplexation), and a high immiscibility with aqueous solutions. These characteristics must be maintained in the chemical, radiation, and mass transport environments present during the separation process. Ionic liquids (ILs) have an almost negligible vapour pressure and high thermal stability. Their ability to dissolve a wide range of substrate molecules and potential to be highly resilient in radiation fields make ILs particularly promising media. The separation efficiency of the biphasic system will depend on many parameters, including the aqueous oxidation state of the targeted metal ion, and the thermodynamics and kinetics of interfacial transport and metal-ligand complex formation at the water/IL interface or in the IL phase. The most uncertain and unstudied area for these applications is the effect of ionizing radiation on the stability and separation efficiency of the biphasic system. The present study investigates the effect of γ-radiation on gas/IL and water/IL interfacial stability and mass transfer with trihexyltetradecylphosphonium bis(trifluoromethyl-sulfonyl)imide, a phosphonium-based IL. The IL, in contact with either gas or water, was irradiated at a dose rate of 6.4 kGy·h-1. Gas-phase samples were analyzed by gas chromatography-mass spectrometry (GC-MS) and the changes in the IL and aqueous phases were monitored by conductivity measurements and Raman spectroscopy. In this paper we discuss these observations and their

  11. Formation of aqueous-phase α-hydroxyhydroperoxides (α-HHP: potential atmospheric impacts

    Directory of Open Access Journals (Sweden)

    R. Zhao

    2013-06-01

    Full Text Available The focus of this work is on quantifying the degree of the aqueous-phase formation of α-hydroxyhydroperoxides (α-HHPs via reversible nucleophilic addition of H2O2 to aldehydes. Formation of this class of highly oxygenated organic hydroperoxides represents a poorly characterized aqueous-phase processing pathway that may lead to enhanced SOA formation and aerosol toxicity. Specifically, the equilibrium constants of α-HHP formation have been determined using proton nuclear-magnetic-resonance (1H NMR spectroscopy and proton-transfer-reaction mass spectrometry (PTR-MS. Significant α-HHP formation was observed from formaldehyde, acetaldehyde, propionaldehyde, glycolaldehyde, glyoxylic acid, and methylglyoxal, but not from methacrolein and ketones. Low temperatures enhanced the formation of α-HHPs but slowed their formation rates. High inorganic salt concentrations shifted the equilibria toward the hydrated form of the aldehydes and slightly suppressed α-HHP formation. Using the experimental equilibrium constants, we predict the equilibrium concentration of α-HHPs to be in the μM level in cloud water, but it may also be present in the mM level in aerosol liquid water (ALW, where the concentrations of H2O2 and aldehydes can be high. Formation of α-HHPs in ALW may significantly affect the effective Henry's law constants of H2O2 and aldehydes but may not affect their gas-phase levels. The photochemistry and reactivity of this class of atmospheric species have not been studied.

  12. Formation of aqueous-phase α-hydroxyhydroperoxides (α-HHP): potential atmospheric impacts

    Science.gov (United States)

    Zhao, R.; Lee, A. K. Y.; Soong, R.; Simpson, A. J.; Abbatt, J. P. D.

    2013-06-01

    The focus of this work is on quantifying the degree of the aqueous-phase formation of α-hydroxyhydroperoxides (α-HHPs) via reversible nucleophilic addition of H2O2 to aldehydes. Formation of this class of highly oxygenated organic hydroperoxides represents a poorly characterized aqueous-phase processing pathway that may lead to enhanced SOA formation and aerosol toxicity. Specifically, the equilibrium constants of α-HHP formation have been determined using proton nuclear-magnetic-resonance (1H NMR) spectroscopy and proton-transfer-reaction mass spectrometry (PTR-MS). Significant α-HHP formation was observed from formaldehyde, acetaldehyde, propionaldehyde, glycolaldehyde, glyoxylic acid, and methylglyoxal, but not from methacrolein and ketones. Low temperatures enhanced the formation of α-HHPs but slowed their formation rates. High inorganic salt concentrations shifted the equilibria toward the hydrated form of the aldehydes and slightly suppressed α-HHP formation. Using the experimental equilibrium constants, we predict the equilibrium concentration of α-HHPs to be in the μM level in cloud water, but it may also be present in the mM level in aerosol liquid water (ALW), where the concentrations of H2O2 and aldehydes can be high. Formation of α-HHPs in ALW may significantly affect the effective Henry's law constants of H2O2 and aldehydes but may not affect their gas-phase levels. The photochemistry and reactivity of this class of atmospheric species have not been studied.

  13. Effects of Mixing Conditions, Oil Type and Aqueous Phase Composition on Some Crude Oil Emulsions

    OpenAIRE

    O. Omole; O.A. Falode

    2005-01-01

    The ease of formation of emulsions is described for some crude oil systems in which the mixing conditions, oil type, aqueous phase composition and concentration are varied. The most stable emulsions have quality that ranged between 10 and 20% while the least stable have quality that ranged between 50 and 60%. Droplet coalescence was highest at 2 min agitation and below 5000 rpm. Addition of 70% FY crude to BL crude caused 24% emulsion stability increase while a decrease of 50% in emulsion sta...

  14. Preparation and adsorption performance of a novel bipolar PS-EDTA resin in aqueous phase

    International Nuclear Information System (INIS)

    A novel chelating resin containing many amino and carboxyl functional groups, PS-EDTA resin, was prepared from chloromethylated polystyrene bead by reacting with ethylenediamine and chloroacetate in aqueous phase in sequence. The structure of PS-EDTA resin was characterized by means of infrared spectroscopy, scanning electron microscopy, surface area analysis and thermogravimetry. Adsorption behavior of the resin for Ag (I) ions in aqueous solutions was investigated by batch experiments. The results indicated that the adsorption removal of PS-EDTA resin for Ag (I) could achieve more than 99.9% at pH values of 5.0 with an initial Ag (I) concentration of 60.0 mg/L within 2 h. The maximum removal capacity of PS-EDTA toward Ag (I) was found to be almost 3314.97 mg/g at 25 deg. C. In addition, adsorption kinetic data were described by pseudo-second-order equation and the equilibrium data fitted very well with the Freundlich model. It was found that the PS-EDTA resin had excellent adsorption properties for Ag (I), so it should be a promising composite adsorbent with application in the recovery of Ag (I) ions from aqueous environment.

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

    Science.gov (United States)

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

    2014-12-01

    This study is based on the assumption that the off-flavour of pea proteins might be decreased using the retention of volatile compounds by a mixture with another biopolymer. The partition of volatile compounds in an aqueous system containing pea protein and maltodextrins was followed under thermodynamic incompatibility conditions. Firstly, the phase diagram of the system was established. Then, the partition of aroma compounds between the phase rich in protein and the phase rich in maltodextrin was measured by SPME-GC-MS. There was a transfer of volatile compounds during phase separation. Variations of pH were also used to vary the retention of volatile compounds by proteins. The concentration of volatile compounds in protein solution at pH 2.4 was higher than at pH 7.2. It was possible to increase the transfer of volatile compounds from the phase rich in protein to the phase rich in maltodextrin using the effect of pH on protein denaturation. PMID:24996351

  16. Tritium distribution ratios between the 30 % tributyl phosphate(TBP)-normal dodecane(nDD) organic phase and uranyl nitrate-nitric acid aqueous phase

    International Nuclear Information System (INIS)

    Tritium distribution ratios between the organic and aqueous phases were measured for the system of 30 % tributyl phosphate(TBP)-normal dodecane(nDD)/uranyl nitrate-nitric acid water. It was confirmed that tritium is extracted by TBP into the organic phase in both chemical forms of tritiated water (HTO) and tritiated nitric acid (TNO3). The value of tritium distribution ratio ranged from 0.002 to 0.005 for the conditions of 0-6 mol/L nitric acid, 0.5-800 mCi/L tritium in aqueous phase, and 0-125 g-U/L uranium in organic phase. Isotopic distribution coefficient of tritium between the organic and aqueous phases was observed to be about 0.95. (author)

  17. Quantification of colloidal and aqueous element transfer in soils: The dual-phase mass balance model

    Science.gov (United States)

    Bern, Carleton R.; Thompson, Aaron; Chadwick, Oliver A.

    2015-01-01

    Mass balance models have become standard tools for characterizing element gains and losses and volumetric change during weathering and soil development. However, they rely on the assumption of complete immobility for an index element such as Ti or Zr. Here we describe a dual-phase mass balance model that eliminates the need for an assumption of immobility and in the process quantifies the contribution of aqueous versus colloidal element transfer. In the model, the high field strength elements Ti and Zr are assumed to be mobile only as suspended solids (colloids) and can therefore be used to distinguish elemental redistribution via colloids from redistribution via dissolved aqueous solutes. Calculations are based upon element concentrations in soil, parent material, and colloids dispersed from soil in the laboratory. We illustrate the utility of this model using a catena in South Africa. Traditional mass balance models systematically distort elemental gains and losses and changes in soil volume in this catena due to significant redistribution of Zr-bearing colloids. Applying the dual-phase model accounts for this colloidal redistribution and we find that the process accounts for a substantial portion of the major element (e.g., Al, Fe and Si) loss from eluvial soil. In addition, we find that in illuvial soils along this catena, gains of colloidal material significantly offset aqueous elemental loss. In other settings, processes such as accumulation of exogenous dust can mimic the geochemical effects of colloid redistribution and we suggest strategies for distinguishing between the two. The movement of clays and colloidal material is a major process in weathering and pedogenesis; the mass balance model presented here is a tool for quantifying effects of that process over time scales of soil development.

  18. Pre-analytic phase in molecular biology: criticism and non-compliance management

    Directory of Open Access Journals (Sweden)

    Catia Sias

    2010-06-01

    Full Text Available Introduction: During workflow in Laboratories the most delicate and important step is pre-analytic sample treatment because it involves more than one operator of the same structure and often different health services. In fact, the biological materials used for the diagnosis should be collected, sent and properly treated before the analytic phase. Correct methods for collecting and handling biological materials, including guidelines to users of laboratory services, improve performance of Laboratory testing activity. In the pre-analytic phase the operators check sample integrity, and prepare the sample for the subsequent analytic phase: in all these steps monitoring and control of “non- compliance” is crucial. Methods: During 2007-2008 we created a “non- compliance” check-list, to monitor errors which occurred in different sectors of the preanalytic phase, particularly in the nucleic acid extraction step. These “non-compliances” are analysed to identify and to remove errors, adopting preventive and corrective proceedings. Since 2008 we have been using DNA/RNA internal controls synthesized in our Laboratory. They can be amplified by the same primers and recognized by different probes. Results: Examination of the “non compliance” check-list for molecular biology investigations shows that the percentage of urine repeat samples decreased from 17% to 2% and the percentage of stool repeat samples from 27% to 2%. Regarding use of internal controls, they allow the assessment of inhibitory factors that can prevent gene amplification. Conclusions: Monitoring “non-compliance” cases and dividing them by typology allow us identifying the most frequent causes of incorrect sample handling, as a non optimal procedure of pre-treatment, thus improving the pre-analytic phase. Therefore by monitoring the preanalytic phase we can prevent the introduction of confounding factors that may negatively influence the accuracy of results and their

  19. Molecular dynamics simulations on aqueous two-phase systems - Single PEG-molecules in solution

    Directory of Open Access Journals (Sweden)

    Oelmeier Stefan A

    2012-08-01

    Full Text Available Abstract Background Molecular Dynamics (MD simulations are a promising tool to generate molecular understanding of processes related to the purification of proteins. Polyethylene glycols (PEG of various length are commonly used in the production and purification of proteins. The molecular mechanisms behind PEG driven precipitation, aqueous two-phase formation or the effects of PEGylation are however still poorly understood. Results In this paper, we ran MD simulations of single PEG molecules of variable length in explicitly simulated water. The resulting structures are in good agreement with experimentally determined 3D structures of PEG. The increase in surface hydrophobicity of PEG of longer chain length could be explained on an atomic scale. PEG-water interactions as well as aqueous two-phase formation in the presence of PO4 were found to be correlated to PEG surface hydrophobicity. Conclusions We were able to show that the taken MD simulation approach is capable of generating both structural data as well as molecule descriptors in agreement with experimental data. Thus, we are confident of having a good in silico representation of PEG.

  20. THERMAL PERFORMANCE OF A TWO PHASE CLOSED THERMOSYPHON USING AQUEOUS SOLUTION

    Directory of Open Access Journals (Sweden)

    M. Karthikeyan

    2010-05-01

    Full Text Available The thermal performance of an inclined two phase closed thermosyphon with different working fluid has been investigated experimentally in this paper. Distilled water and an aqueous solution that has a positive gradient of surface tension with temperature are used as the working fluid. A copper thermosyphon with a length of 1000 mm long, an inner diameter of 17 mm and an outer diameter of 19 mm was mployed. Each thermosyphon was charged with 60% of the working fluid and was tested with an evaporator length of 400 mm and condenser length of 450 mm. The thermosyphon was tested for various inclinations of 45○, 60○ and 90○ to the horizontal. Flow rate of 0.08Kg/min, 0.1 Kg/min and 0.12 Kg/min and heat input of 40 W, 60 W and 80 W were taken as input parameters. The thermal performance of aqueous solution charged two phase closed thermosyphon was out performed the distilled water in both heat transfer and temperature distribution.

  1. Aqueous phase adsorption of different sized molecules on activated carbon fibers: Effect of textural properties.

    Science.gov (United States)

    Prajapati, Yogendra N; Bhaduri, Bhaskar; Joshi, Harish C; Srivastava, Anurag; Verma, Nishith

    2016-07-01

    The effect that the textural properties of rayon-based activated carbon fibers (ACFs), such as the BET surface area and pore size distribution (PSD), have on the adsorption of differently sized molecules, namely, brilliant yellow (BY), methyl orange (MO) and phenol (PH), was investigated in the aqueous phase. ACF samples with different BET areas and PSDs were produced by steam-activating carbonized fibers for different activation times (0.25, 0.5, and 1 h). The samples activated for 0.25 h were predominantly microporous, whereas those activated for relatively longer times contained hierarchical micro-mesopores. The adsorption capacities of the ACFs for the adsorbate increased with increasing BET surface area and pore volume, and ranged from 51 to 1306 mg/g depending on the textural properties of the ACFs and adsorbate size. The adsorption capacities of the hierarchical ACF samples followed the order BY > MO > PH. Interestingly, the number of molecules adsorbed by the ACFs followed the reverse order: PH > MO > BY. This anomaly was attributed to the increasing molecular weight of the PH, MO and BY molecules. The equilibrium adsorption data were described using the Langmuir isotherm. This study shows that suitable textural modifications to ACFs are required for the efficient aqueous phase removal of an adsorbate. PMID:27107386

  2. Approximate Analytic Solutions for the Two-Phase Stefan Problem Using the Adomian Decomposition Method

    Directory of Open Access Journals (Sweden)

    Xiao-Ying Qin

    2014-01-01

    Full Text Available An Adomian decomposition method (ADM is applied to solve a two-phase Stefan problem that describes the pure metal solidification process. In contrast to traditional analytical methods, ADM avoids complex mathematical derivations and does not require coordinate transformation for elimination of the unknown moving boundary. Based on polynomial approximations for some known and unknown boundary functions, approximate analytic solutions for the model with undetermined coefficients are obtained using ADM. Substitution of these expressions into other equations and boundary conditions of the model generates some function identities with the undetermined coefficients. By determining these coefficients, approximate analytic solutions for the model are obtained. A concrete example of the solution shows that this method can easily be implemented in MATLAB and has a fast convergence rate. This is an efficient method for finding approximate analytic solutions for the Stefan and the inverse Stefan problems.

  3. An analytical inductor design procedure for three-phase PWM converters in power factor correction applications

    DEFF Research Database (Denmark)

    Kouchaki, Alireza; Niroumand, Farideh Javidi; Haase, Frerk; Nymand, Morten

    This paper presents an analytical method for designing the inductor of three-phase power factor correction converters (PFCs). The complex behavior of the inductor current complicates the inductor design procedure as well as the core loss and copper loss calculations. Therefore, this paper analyze...

  4. An analytical description of longitudinal phase space distortions in magnetic bunch compressors

    International Nuclear Information System (INIS)

    In this paper we consider a possible mechanism of strong distortions of longitudinal phase space due to collective effects in an electron bunch passing a bunch compressor. Analytical expressions are derived for the case of a linear compression. Estimates for the TESLA Test Facility at DESY are presented

  5. Phase diagrams of ionic liquids-based aqueous biphasic systems as a platform for extraction processes

    International Nuclear Information System (INIS)

    Highlights: • Novel ABS based in ionic liquids were determined as a platform for distinct extraction processes. • The effect of pH, IL cation core, alkyl side chain length, IL anion nature, and salt nature on the ABS formation was investigated. • The ability to form ABS increases with the pH and alkyl chain length for all systems studied. • The ILs cation core and anion nature effect on the ABS formation is dominated by the IL (hydrophobic/hydrophilic) nature. • The effect of the different salts depends of the ionic liquid nature and salt valency. - Abstract: In the past few years, ionic liquid-based aqueous biphasic systems have become the subject of considerable interest as a promising technique for the extraction and purification of several macro/biomolecules. Aiming at developing guidelines for more benign and efficient extraction processes, phase diagrams for aqueous biphasic systems composed of ionic liquids and inorganic/organic salts are here reported. Several combinations of ionic liquid families (imidazolium, pyridinium, phosphonium, quaternary ammonium and cholinium) and salts [potassium phosphate buffer (KH2PO4/K2HPO4 at pH 7), potassium citrate buffer (C6H5K3O7/C6H8O7 at pH 5, 6, 7 and 8) and potassium carbonate (K2CO3 at pH ∼13)] were evaluated to highlight the influence of the ionic liquid structure (cation core, anion and alkyl chain length), the pH and the salt nature on the formation of aqueous biphasic systems. The binodal curves and respective tie-lines reported for these systems were experimentally determined at (298 ± 1) K. In general, the ability to promote the aqueous biphasic systems formation increases with the pH and alkyl chain length. While the influence of the cation core and anion nature of the ionic liquids on their ability to form aqueous biphasic systems closely correlates with ionic liquids capacity to be hydrated by water, the effect of the different salts depends of the ionic liquid nature and salt valency

  6. Interplay of capillarity, drainage height, and aqueous phase saturation on mass transfer rate of solvent vapor into heavy oil

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadloo, F.; Asghari, K.; Freitag, N.P. [Society of Petroleum Engineers (Canada); Henni, A. [University of Regina (United States)

    2011-07-01

    The vapor extraction process has emerged as a potentially effective solvent based gravity drainage-based recovery technique in low-pressure and shallow recovery oil and bitumen reservoirs. The performance of this process depends on the efficiency of the mass transfer rate between the solvent and heavy oil and bitumen. For reliable prediction of production rates, a realistic approximation of diffusion and convective dispersion at the edge of the vapor chamber is required. To address this issue, a comprehensive experimental study is presented that systematically investigates the interplay of capillarity, drainage height, and aqueous phase saturation on the efficiency of the mass transfer rate of solvent vapor into the heavy oil. To simulate the vapor extraction process, a novel experimental approach is described that eliminates the effect of pressure disturbances. Analytical models were made to determine the effective diffusion coefficient. From the study, it was noticed that effective diffusion coefficients in the presence of immobile water saturation are higher than those derived in the absence of immobile water saturation.

  7. Secondary organic aerosol (trans)formation through aqueous phase guaiacol photonitration: chemical characterization of the products

    Science.gov (United States)

    Grgić, Irena; Kitanovski, Zoran; Kroflič, Ana; Čusak, Alen

    2014-05-01

    One of the largest primary sources of organic aerosol in the atmosphere is biomass burning (BB) (Laskin et al. 2009); in Europe its contribution to annual mean of PM10 is between 3 and 14 % (Maenhaut et al. 2012). During the process of wood burning many different products are formed via thermal degradation of wood lignin. Hardwood burning produces mainly syringol (2,6-dimetoxyphenol) derivatives, while softwood burning exclusively guaiacol (2-methoxyphenol) and its derivatives. Taking into account physical properties of methoxyphenols only, their concentrations in atmospheric waters might be underestimated. So, their aqueous phase reactions can be an additional source of SOA, especially in regions under significant influence of wood combustion. An important class of compounds formed during physical and chemical aging of the primary BBA in the atmosphere is nitrocatechols, known as strong absorbers of UV and Vis light (Claeys et al. 2012). Very recently, methyl-nitrocatechols were proposed as suitable markers for highly oxidized secondary BBA (Iinuma et al. 2010, Kitanovski et al. 2012). In the present work, the formation of SOA through aqueous phase photooxidation and nitration of guaiacol was examined. The key objective was to chemically characterize the main low-volatility products and further to check their possible presence in the urban atmospheric aerosols. The aqueous phase reactions were performed in a thermostated reactor under simulated sunlight in the presence of H2O2 and nitrite. Guaiacol reaction products were first concentrated by solid-phase extraction (SPE) and then subjected to semi-preparative liquid chromatography.The main product compounds were fractionated and isolated as pure solids and their structure was further elucidated by using nuclear magnetic resonance spectroscopy (1H, 13C and 2D NMR) and direct infusion negative ion electro-spray ionization tandem mass spectrometry (( )ESI-MS/MS). The main photonitration products of guaiacol (4

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

    Energy Technology Data Exchange (ETDEWEB)

    Chokejaroenrat, Chanat, E-mail: chanat@sut.ac.th [Department of Civil Engineering, University of Nebraska, Lincoln, NE 68588-0531 (United States); School of Environmental Engineering, Institute of Engineering, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Comfort, Steve, E-mail: scomfort1@unl.edu [School of Natural Resources, University of Nebraska, Lincoln, NE 68583-0915 (United States); Sakulthaew, Chainarong, E-mail: cvtcns@ku.ac.th [School of Natural Resources, University of Nebraska, Lincoln, NE 68583-0915 (United States); Department of Veterinary Technology, Kasetsart University, Bangkok 10900 (Thailand); Dvorak, Bruce, E-mail: bdvorak1@unl.edu [Department of Civil Engineering, University of Nebraska, Lincoln, NE 68588-0531 (United States)

    2014-03-01

    Graphical abstract: - Highlights: • Transport experiments used transmissive and low permeability zones (LPZs). • {sup 14}C-labeled TCE was used to quantify oxidation of DNAPL in LPZs by permanganate. • Stabilization aids prevented MnO{sub 2} rind formation. • DNAPL oxidation improved when xanthan and stabilization aids were used. - Abstract: Treating dense non-aqueous phase liquids (DNAPLs) embedded in low permeability zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate (MnO{sub 4}{sup −}) into LPZs to treat high concentrations of TCE. This was accomplished by conducting transport experiments that quantified the penetration of various permanganate flooding solutions into a LPZ that was spiked with non-aqueous phase {sup 14}C-TCE. The treatments we evaluated included permanganate paired with: (i) a shear-thinning polymer (xanthan); (ii) stabilization aids that minimized MnO{sub 2} rind formation and (iii) a phase-transfer catalyst. In addition, we quantified the ability of these flooding solutions to improve TCE destruction under batch conditions by developing miniature LPZ cylinders that were spiked with {sup 14}C-TCE. Transport experiments showed that MnO{sub 4}{sup −} alone was inefficient in penetrating the LPZ and reacting with non-aqueous phase TCE, due to a distinct and large MnO{sub 2} rind that inhibited the TCE from further oxidant contact. By including xanthan with MnO{sub 4}{sup −}, the sweeping efficiency increased (90%) but rind formation was still evident. By including the stabilization aid, sodium hexametaphosphate (SHMP) with xanthan, permanganate penetrated 100% of the LPZ, no rind was observed, and the percentage of TCE oxidized increased. Batch experiments using LPZ cylinders allowed longer contact times between the flooding solutions and the DNAPL and results showed that SHMP + MnO{sub 4}{sup −} improved TCE destruction by

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

    International Nuclear Information System (INIS)

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

  10. Analytical solution of laminar-laminar stratified two-phase flows with curved interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Brauner, N.; Rovinsky, J.; Maron, D.M. [Tel-Aviv Univ. (Israel)

    1995-09-01

    The present study represents a complete analytical solution for laminar two-phase flows with curved interfaces. The solution of the Navier-Stokes equations for the two-phases in bipolar coordinates provides the `flow monograms` describe the relation between the interface curvature and the insitu flow geometry when given the phases flow rates and viscosity ratios. Energy considerations are employed to construct the `interface monograms`, whereby the characteristic interfacial curvature is determined in terms of the phases insitu holdup, pipe diameter, surface tension, fluids/wall adhesion and gravitation. The two monograms are then combined to construct the system `operational monogram`. The `operational monogram` enables the determination of the interface configuration, the local flow characteristics, such as velocity profiles, wall and interfacial shear stresses distribution as well as the integral characteristics of the two-phase flow: phases insitu holdup and pressure drop.

  11. Analytical solution of laminar-laminar stratified two-phase flows with curved interfaces

    International Nuclear Information System (INIS)

    The present study represents a complete analytical solution for laminar two-phase flows with curved interfaces. The solution of the Navier-Stokes equations for the two-phases in bipolar coordinates provides the 'flow monograms' describe the relation between the interface curvature and the insitu flow geometry when given the phases flow rates and viscosity ratios. Energy considerations are employed to construct the 'interface monograms', whereby the characteristic interfacial curvature is determined in terms of the phases insitu holdup, pipe diameter, surface tension, fluids/wall adhesion and gravitation. The two monograms are then combined to construct the system 'operational monogram'. The 'operational monogram' enables the determination of the interface configuration, the local flow characteristics, such as velocity profiles, wall and interfacial shear stresses distribution as well as the integral characteristics of the two-phase flow: phases insitu holdup and pressure drop

  12. Experimental determination and thermodynamic modeling of phase equilibrium and protein partitioning in aqueous two-phase systems containing biodegradable salts

    International Nuclear Information System (INIS)

    Highlights: ► Binodal data of systems (water + polyethyleneglycol + sodium) succinate are reported. ► Pitzer model describes the phase equilibrium of systems formed by polyethyleneglycol and biodegradable salts satisfactorily. ► This simple thermodynamic framework was able to predict the partitioning behaviour of model proteins acceptably well. - Abstract: Phase diagrams of sustainable aqueous two-phase systems (ATPSs) formed by polyethyleneglycols (PEGs) of different average molar masses (4000, 6000, and 8000) and sodium succinate are reported in this work. Partition coefficients (Kps) of seven model proteins: bovine serum albumin, catalase, beta-lactoglobulin, alpha-amylase, lysozyme, pepsin, urease and trypsin were experimentally determined in these systems and in ATPSs formed by the former PEGs and other biodegradable sodium salts: citrate and tartrate. An extension of Pitzer model comprising long and short-range term contributions to the excess Gibbs free energy was used to describe the (liquid + liquid) equilibrium. Comparison between experimental and calculated tie line data showed mean deviations always lower than 3%, thus indicating a good correlation. The partition coefficients were modeled by using the same thermodynamic approach. Predicted and experimental partition coefficients correlated quite successfully. Mean deviations were found to be lower than the experimental uncertainty for most of the assayed proteins.

  13. CFD Analysis of Multi-Phase Reacting Transport Phenomena in Discharge Process of Non-Aqueous Lithium-Air Battery

    OpenAIRE

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

    2015-01-01

    A computational fluid dynamics (CFD) model is developed for rechargeable non-aqueous electrolyte lithium-air batteries with a partial opening for oxygen supply to the cathode. Multi-phase transport phenomena occurred in the battery are considered, including dissolved lithium ions and oxygen gas in the liquid electrolyte, solid-phase electron transfer in the porous functional materials and liquid-phase charge transport in the electrolyte. These transport processes are coupled with the electroc...

  14. Single step aqueous two-phase extraction for downstream processing of C-phycocyanin from Spirulina platensis

    OpenAIRE

    Chethana, S.; Nayak, Chetan A.; M.C. Madhusudhan; Raghavarao, K. S. M. S.

    2014-01-01

    C-phycocyanin, a natural food colorant, is gaining importance worldwide due to its several medical and pharmaceutical applications. In the present study, aqueous two-phase extraction was shown to be an attractive alternative for the downstream processing of C-phycocyanin from Spirulina platensis. By employing differential partitioning, C-phycocyanin selectively partitioned to the polymer rich (top) phase in concentrated form and contaminant proteins to the salt rich (bottom) phase. This resul...

  15. Sonochemical preparation of copper sulfides with different phases in aqueous solutions

    International Nuclear Information System (INIS)

    Highlights: ► Sonochemical preparation of copper sulfides in aqueous solutions is reported. ► CuS and Cu2S nanoparticles with crystallite sizes between 7 and 18 nm were obtained. ► Crystallite size can be changed using different complexing agents. ► Thermal behavior was studied by TG and XRD measurements. - Abstract: There is a growing interest in the synthesis of nanostructured copper sulfides due to their ability to form compounds with various stoichiometries. We report a sonochemical route for the preparation of copper sulfides with different compositions in aqueous solutions, using different, general and convenient copper sources such as copper acetate, copper hydroxide or basic copper carbonate and thiourea or thioacetamide as sulfur precursors under ambient air. Phase analysis, purity and morphology of the products were studied by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The results revealed that nanoparticles of covellite, CuS, with crystallite sizes between 7 and 18 nm can be obtained by using different precursors and complexing agents and that chalcocite, Cu2S, can also be prepared sonochemically

  16. Sonochemical preparation of copper sulfides with different phases in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kristl, Matjaž, E-mail: matjaz.kristl@uni-mb.si [Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova 17, 2000 Maribor (Slovenia); Hojnik, Nuša [Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova 17, 2000 Maribor (Slovenia); Gyergyek, Sašo [Jožef Stefan Institute, Department for Material Synthesis, Jamova 39, 1000 Ljubljana (Slovenia); Drofenik, Miha [Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova 17, 2000 Maribor (Slovenia); Jožef Stefan Institute, Department for Material Synthesis, Jamova 39, 1000 Ljubljana (Slovenia)

    2013-03-15

    Highlights: ► Sonochemical preparation of copper sulfides in aqueous solutions is reported. ► CuS and Cu{sub 2}S nanoparticles with crystallite sizes between 7 and 18 nm were obtained. ► Crystallite size can be changed using different complexing agents. ► Thermal behavior was studied by TG and XRD measurements. - Abstract: There is a growing interest in the synthesis of nanostructured copper sulfides due to their ability to form compounds with various stoichiometries. We report a sonochemical route for the preparation of copper sulfides with different compositions in aqueous solutions, using different, general and convenient copper sources such as copper acetate, copper hydroxide or basic copper carbonate and thiourea or thioacetamide as sulfur precursors under ambient air. Phase analysis, purity and morphology of the products were studied by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The results revealed that nanoparticles of covellite, CuS, with crystallite sizes between 7 and 18 nm can be obtained by using different precursors and complexing agents and that chalcocite, Cu{sub 2}S, can also be prepared sonochemically.

  17. A Novel Approach for Microencapsulation of Nanoemulsions to Overcome the Oxidation of Bioactives in Aqueous Phase

    Directory of Open Access Journals (Sweden)

    Haroon Jamshaid Qazi

    2015-02-01

    Full Text Available Microencapsulation is a promising technique to retain the physical attributes of nanoemulsions and to overcome the oxidation of bioactives that become more available to aqueous phase during emulsification. Purity Gum Ultra (PGU and Hi-CAP 100 (HiCap emulsified nanoemulsions of Clove Oil (CO co-encapsulated with Canola oil (CA and Medium Chain Triglyceride (MCT (5:5% v/v CO:CA and CO:MCT were prepared through high pressure homogenization. Microencapsulation of nanoemulsions was performed using Whey Protein Isolates (WPI under vacuum using freeze drying, which is considered as appropriate method for heat sensitive compounds. The reconstituted emulsions of microencapsulated powder had similar particle sizes as that of fresh nanoemulsions while uncoated showed a big increase (<400 nm. Oxidation of bioactives with and without CO, before and after freeze drying was investigated at different intervals during 60 days of storage at 4 and 25°C by Thiobarbituric Acid Reactive Substances (TBARS assay. Microencapsulated PGU-CO:CA showed minimum TBARS values compared to other emulsions. Gas chromatography analysis of microcapsules also showed higher retention of CO and lower content on the interphase for aqueous interaction. Conclusively, this study proposes a novel strategy using a freeze drying process to microencapsulate nanoemulsion.

  18. Aqueous phase hydration and hydrate acidity of perfluoroalkyl and n:2 fluorotelomer aldehydes.

    Science.gov (United States)

    Rayne, Sierra; Forest, Kaya

    2016-06-01

    The SPARC software program and comparative density functional theory (DFT) calculations were used to investigate the aqueous phase hydration equilibrium constants (Khyd) of perfluoroalkyl aldehydes (PFAlds) and n:2 fluorotelomer aldehydes (FTAlds). Both classes are degradation products of known industrial compounds and environmental contaminants such as fluorotelomer alcohols, iodides, acrylates, phosphate esters, and other derivatives, as well as hydrofluorocarbons and hydrochlorofluorocarbons. Prior studies have generally failed to consider the hydration, and subsequent potential hydrate acidity, of these compounds, resulting in incomplete and erroneous predictions as to their environmental behavior. In the current work, DFT calculations suggest that all PFAlds will be dominantly present as the hydrated form in aqueous solution. Both SPARC and DFT calculations suggest that FTAlds will not likely be substantially hydrated in aquatic systems or in vivo. PFAld hydrates are expected to have pKa values in the range of phenols (ca. 9 to 10), whereas n:2 FTAld hydrates are expected to have pKa values ca. 2 to 3 units higher (ca. 12 to 13). In order to avoid spurious modeling predictions and a fundamental misunderstanding of their fate, the molecular and/or dissociated hydrate forms of PFAlds and FTAlds need to be explicitly considered in environmental, toxicological, and waste treatment investigations. The results of the current study will facilitate a more complete examination of the environmental fate of PFAlds and FTAlds. PMID:26980678

  19. Characterization of complex non-aqueous phase liquids (NAPLs) in the subsurface environment: partitioning and interfacial tracer tests and numerical dissolution assessment

    OpenAIRE

    Piepenbrink, Matthias

    2007-01-01

    Contamination of the subsurface environment by complex organic non-aqueous phase liquids (NAPLs) and the resulting release of carcinogenic or mutagenic organic compounds impose a serious risk on groundwater quality. Due to the low aqueous solubilities of the individual organic components the rate of mass transfer from the non-aqueous phase to the water phase is very slow, thus NAPL source zones typically represent long-term contamination problems with organic compounds leaching into the...

  20. Partition of Chiral pharmaceutical intermediate R(-)-Mandelic Acid in Aqueous Two-Phase System of Poly(ethylene glycol)-Ammonium Sulfate

    Institute of Scientific and Technical Information of China (English)

    Xu Xiaoping; Li Zhongqin; Chen Jiebo; Huang Xinghua

    2004-01-01

    An aqueous two-phase system of poly (ethylene glycol)-ammonium sulfate was employed to separate R (-)-mandelic acid.The result showed that R (-)-mandelic acid has priority to partition in PEG-rich top phase. This indicated that aqueous two-phase is a very suitable system for separation of R(-)-mandelic acid.

  1. Aqueous-phase behavior and vesicle formation of natural glycolipid biosurfactant, mannosylerythritol lipid-B.

    Science.gov (United States)

    Worakitkanchanakul, Wannasiri; Imura, Tomohiro; Fukuoka, Tokuma; Morita, Tomotake; Sakai, Hideki; Abe, Masahiko; Rujiravanit, Ratana; Chavadej, Sumaeth; Minamikawa, Hiroyuki; Kitamoto, Dai

    2008-08-01

    Mannosylerythritol lipids (MELs) are one of the most promising glycolipid biosurfactants produced by yeast strains of the genus Pseudozyma. In this study, the aqueous-phase behavior of a new monoacetyl MEL derivative, 1-O-beta-(2',3'-di-O-alka(e)noyl-6'-O-acetyl-d-mannopyranosyl)-d-erythritol (MEL-B), was investigated using polarized optical microscopy, small-angle X-ray scattering (SAXS), confocal laser scanning microscopy (CLSM), and differential scanning calorimetry (DSC). The present MEL-B was found to self-assemble into a lamellar (L(alpha)) phase over remarkably wide concentration and temperature ranges. According to SAXS measurement, the interlayer spacing (d) was estimated to be almost constant (about 4.7 nm) at the low MEL-B concentration (60 wt.%) region, the d-spacing gradually decreased to 3.1 nm with an increase in the MEL-B concentration. The thermal stability of the liquid crystalline phase was investigated by DSC measurement. The obtained L(alpha) phase was found to be stable up to 95 degrees C below a MEL-B concentration of 85 wt.%; then, the melting temperature of the liquid crystalline phase dramatically decreased with an increase in MEL-B concentration (above 85 wt.%). Furthermore, we found relatively large vesicles (1-5 microm) at the low MEL-B concentration using CLSM observation. The trapped volume of the obtained MEL-B vesicle was estimated to be about 0.42 microL/mumol by glucose dialysis method. These results suggest that the natural glycolipid biosurfactant, the newly found MEL-B, would be useful in various fields of applications as an L(alpha) phase- and/or vesicle-forming lipid. PMID:18456469

  2. REMOVAL OF METHYLENE BLUE FROM AQUEOUS PHASE BY PRETREATED WALNUT SHELL IN A PACKED COLUMN

    Directory of Open Access Journals (Sweden)

    A.A. Nazari-Moghaddam

    2010-01-01

    Full Text Available Methylene blue (MB adsorption from aqueous phase was investigated. Pretreated walnut shell, as adsorbent was used. Experiments were conducted in a batch system for determination of sorption equilibria and then the data were incorporated in a packed column for the removal of MB from synthetic wastewater. The generated wastewater was contained 4 mg/l of MB. The wastewater was pumped through the column with flow rate of 18 ml/min and the effluent samples were collected. The effect of influent MB concentration (4 and 8 mg/l and pH (5, 7 and 9 of wastewater on removal efficiency of dye were investigated. Langmuir adsorption isotherm model was implemented to interpret the experimental data. The obtained results revealed that the sorption data were well described by Langmuir model at pH value of 9. At contact time of 300 min, maximum equilibrium adsorption of MB uptake 6.7mg/g adsorbent was achieved.

  3. The Distribution of Plutonium(Ⅲ,Ⅳ) Nitrate Between Dilute TBP/OK and Aqueous Phase

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The distribution of plutonium (Ⅲ, Ⅳ) nitrate between dilute TBP/OK and aqueous phase is systematically investigated. On the basis of the preparation and stabilization of Pu(Ⅲ, Ⅳ), the influences of the concentration of HNO3, Al(NO3)3, TBP and UO2(NO3)2 on the distribution ratio of them are studied at 25℃. The results indicate that the distribution ratio of Pu(Ⅳ) has a maximum while that of Pu(Ⅲ) increases with the concentration of HNO3. The distribution ratio of Pu(Ⅲ, Ⅳ) increases along with the concentration of Al(NO3)3 and TBP. The extraction reaction

  4. Poly(ionic liquid)s as phase splitting promoters in aqueous biphasic systems.

    Science.gov (United States)

    João, Karen G; Tomé, Liliana C; Isik, Mehmet; Mecerreyes, David; Marrucho, Isabel M

    2015-11-01

    Aqueous biphasic systems (ABSs) provide a sustainable and efficient alternative to conventional liquid-liquid extraction techniques with volatile organic solvents, and can be used for the extraction, recovery, and purification of diverse solutes. In this work, and for the first time, ABSs composed of poly(ionic liquid)s (PILs) and inorganic salts were measured at 25 °C and atmospheric pressure. New PILs having pyrrolidinium polycations combined with different counter-anions, namely acetate [Ac](-), trifluoroacetate [TFAc](-), hexanoate [Hex](-), adipate [Adi](-), and citrate [Cit](-) were synthesized, by a simple and environmentally-friendly procedure, and characterized. The effect of the PIL features, namely molecular weight and anionic character, and other experimental variables, such as temperature, on the phase splitting ability was researched. The aptitude of the studied ABS to be implemented as separation technologies was also evaluated through the use of a model biomolecule, tryptophan. PMID:26421939

  5. Oxidation of 1,4-dichloro-2-butene by aqueous sodium hypochlorite under phase transfer conditions

    Energy Technology Data Exchange (ETDEWEB)

    Grigoryan, G.S.; Karoyan, I.L.; Malkhasyan, A.Ts.; Martirosyan, G.T.; Artamkina, G.A.; Beletskaya, I.P.

    1987-11-10

    In the industrial process for the production of chloroprene from butadiene, the problem of reducing the organic impurities in the waste water to 2000 mg/liter has not yet been solved. A method has been patented for the oxidation of organic compounds by sodium hypochlorite at high temperatures and high pressure but this method is limited by the oxidation of soluble organic compounds. The oxidation of 1,4-dichloro-2-butene by aqueous sodium hypochlorite was studied. A sharp increase in the reaction rate was found in the presence of phase transfer catalysts and surfactants. The involvement of oxygen as a cooxiant and the effect of surfactants on the absorption of atmospheric oxygen by the reaction system were demonstrated.

  6. Direct recovery of cyclodextringlycosyltransferase from Bacillus cereus using aqueous two-phase flotation.

    Science.gov (United States)

    Lin, Yu Kiat; Show, Pau Loke; Yap, Yee Jiun; Tan, Chin Ping; Ng, Eng-Poh; Ariff, Arbakariya B; Mohamad Annuar, Mohamad Suffian B; Ling, Tau Chuan

    2015-12-01

    Purification of cyclodextrin glycosyl transferase (CGTase) from Bacillus cereus using polyethylene glycol (PEG)-potassium phosphates aqueous two-phase flotation (ATPF) system was studied in this paper. The effects of varying PEG molecular weight, tie-line length (TLL) value, volume ratio (VR), pH value, crude concentration and gas nitrogen flotation time were investigated. The optimal condition for purification of CGTase was attained at 18.0% (w/w) PEG 8000, 7.0% (w/w) potassium phosphates, VR of 3.0, 20% (w/w) crude load at pH 7, and 80 min nitrogen flotation time at a flow rate of 5 L/min. With this optimal condition, purification factor (PFT) of 21.8 and a yield (YT) of 97.1% were attained. CGTase was successfully purified in a single downstream processing step using the ATPF. PMID:26111602

  7. Softness and non-spherical shape define the phase behavior and the structural properties of lysozyme in aqueous solutions

    Science.gov (United States)

    Baumketner, A.; Melnyk, R.; Holovko, M. F.; Cai, W.; Costa, D.; Caccamo, C.

    2016-01-01

    In this study, Boltzmann inversion is applied in conjunction with molecular dynamics simulations to derive inter-molecular potential for protein lysozyme in aqueous solution directly from experimental static structure factor. The potential has a soft repulsion at short distances and an attraction well at intermediate distances that give rise to the liquid-liquid phase separation. Moreover, Gibbs ensemble Monte Carlo simulations demonstrate that a non-spherical description of lysozyme is better suited to correctly reproduce the experimentally observed properties of such a phase separation. Our findings shed new light on the common problem in molecular and cell biology: "How to model proteins in their natural aqueous environments?"

  8. Analytical Determining Of The Steinmetz Equivalent Diagram Elements Of Single-Phase Transformer

    Directory of Open Access Journals (Sweden)

    T. Aly Saandy

    2015-08-01

    Full Text Available This article presents to an analytical calculation methodology of the Steinmetz Equivalent Diagram Elements applied to the prediction of Eddy current loss in a single-phase transformer. Based on the electrical circuit theory the active and reactive powers consumed by the core are expressed analytically in function of the electromagnetic parameters as resistivity permeability and the geometrical dimensions of the core. The proposed modeling approach is established with the duality parallel series. The equivalent diagram elements empirically determined by Steinmetz are analytically expressed using the expressions of the no loaded transformer consumptions. To verify the relevance of the model validations both by simulations with different powers and measurements were carried out to determine the resistance and reactance of the core. The obtained results are in good agreement with the theoretical approach and the practical results.

  9. A rapid and sensitive assay of perfluorocarboxylic acids in aqueous matrices by headspace solid phase microextraction-gas chromatography-triple quadrupole mass spectrometry.

    Science.gov (United States)

    Monteleone, Marcello; Naccarato, Attilio; Sindona, Giovanni; Tagarelli, Antonio

    2012-08-17

    The work aims at developing a rapid and sensitive method for the quantification of perfluorocarboxylic acids in aqueous matrices. The proposed analytical approach is based on the use of solid phase microextraction in headspace mode after a fast derivatization of the carboxylate function by propylchloroformate/propanol mixture. Several fibers were evaluated and the optimization of the parameters affecting the SPME process was carried out using a central composite design. The optimum working conditions in terms of response values were achieved by performing analysis with CAR/PDMS fiber at room temperature, without addition of NaCl, with a sample volume of 6 ml and an extraction time of 10 min. Assay of PFCAs was performed by using a gas chromatography-triple quadrupole mass spectrometry (GC-QqQ MS) system in negative chemical ionization mode with ammonia as reagent gas. An overall evaluation of all analytical parameters shows that the proposed method provides satisfactory results. In particular, the observed accuracies, ranging from 84.4% to 116.8%, and the RSD values in the range 0.4% and 14.5% confirm the effectiveness of the developed protocol in the assay of PFCAs content in aqueous matrices. Moreover, LOD and LOQ values ranging from 0.08 to 6.6 ng l(-1) and from 0.17 to 14.3 ng l(-1), respectively, can be considered very satisfactory. None of the compounds were detected in six samples of river collected in Calabria. PMID:22762954

  10. Online Investigation of Aqueous-Phase Electrochemical Reactions by Desorption Electrospray Ionization Mass Spectrometry

    Science.gov (United States)

    Lu, Mei; Liu, Yong; Helmy, Roy; Martin, Gary E.; Dewald, Howard D.; Chen, Hao

    2015-08-01

    Electrochemistry (EC) combined with mass spectrometry (MS) is a powerful tool for elucidation of electrochemical reaction mechanisms. However, direct online analysis of electrochemical reaction in aqueous phase was rarely explored. This paper presents the online investigation of several electrochemical reactions with biological relevance in the aqueous phase, such as nitrosothiol reduction, carbohydrate oxidation, and carbamazepine oxidation using desorption electrospray ionization mass spectrometry (DESI-MS). It was found that electroreduction of nitrosothiols [e.g., nitrosylated insulin B (13-23)] leads to free thiols by loss of NO, as confirmed by online MS analysis for the first time. The characteristic mass shift of 29 Da and the reduced intensity provide a quick way to identify nitrosylated species. Equally importantly, upon collision-induced dissociation (CID), the reduced peptide ion produces more fragment ions than its nitrosylated precursor ion (presumably the backbone fragmentation cannot compete with the facile NO loss for the precursor ion), thus facilitating peptide sequencing. In the case of saccharide oxidation, it was found that glucose undergoes electro-oxidation to produce gluconic acid at alkaline pH, but not at neutral and acidic pHs. Such a pH-dependent electrochemical behavior was also observed for disaccharides such as maltose and cellobiose. Upon electrochemical oxidation, carbamazepine was found to undergo ring contraction and amide bond cleavage, which parallels the oxidative metabolism observed for this drug in leucocytes. The mechanistic information of these redox reactions revealed by EC/DESI-MS would be of value in nitroso-proteome research and carbohydrate/drug metabolic studies.

  11. Aqueous phase reforming of sorbitol to bio-gasoline over Ni/HZSM-5 catalysts

    International Nuclear Information System (INIS)

    Highlights: ► Development of an efficient bifunctional Ni/HZSM-5 catalyst for aqueous phase reforming of sorbitol. ► Optimizing the reaction process parameters for bio-gasoline production. ► Optimizing the interaction between Ni species and zeolite by calcination. -- Abstract: Liquid fuel such as bio-gasoline derived from biomass is widely recognized as a potential substitution for the diminishing fossil fuels due to its abundance of raw materials and lower greenhouse gas emissions. In this work, Ni/HZSM-5 catalysts were developed by incipient impregnation method and applied in the bio-gasoline production by aqueous phase reforming of sorbitol. The effects of reaction temperature, hydrogen pressure and calcination temperature of the catalysts on the catalytic performance were investigated. The activity test results showed that the catalyst calcined at 500 °C had the maximal activity with 47.6% of the bio-gasoline yield and 76.4% of the total selectivity of lighter alkanes (C5-C6) at 240 °C and 4.0 MPa. The catalysts were characterized by N2 physical adsorption, H2 temperature-programmed reduction (H2-TPR), H2 temperature-programmed desorption (H2-TPD), and infrared spectroscopy (IR) techniques. The characterization results revealed that the catalyst calcined at 500 °C can provide optimum surface area and pore volume for the reaction. Moreover, 100% of the reducibility of Ni species was detected on the surface of HZSM-5, following by more nickel active sites, which led to a visible increase in the yield of bio-gasoline.

  12. Directing carbon nanotubes from aqueous phase to o/w interface for heavy metal uptaking.

    Science.gov (United States)

    Gao, Lili; Yin, Huayi; Mao, Xuhui; Zhu, Hua; Xiao, Wei; Wang, Dihua

    2015-09-01

    Separation and reuse of dispersed nanoparticles are major obstacles to the extensive application of nano-sized absorbents in wastewater treatment. Herein, we demonstrate the capability of directing acid-oxidized carbon nanotubes (CNTs) as the transfer vehicles of heavy metal ions from simulated wastewater. The heavy metal-loaded CNTs can be readily separated from the aqueous phase via the aggregation process at an oil/water (o/w) interface. The minimum surfactant amount to achieve 99 % transfer ratio (Tr) of 100 mg/L CNTs from water phase to o/w interface was ∼0.01 mM. The adsorption experiments showed that the removal efficiency of the divalent lead ions increased with an increase in CNT mass, and the subsequent addition of cetyltrimethylammonium bromide (CTAB) surfactant did not negatively impact the removal of soluble divalent lead species (Pb(II)). In a wide region of pH and ionic strength, both the decontamination of Pb(II) and the transfer of CNTs from water phase to o/w interface can be accomplished successively. The method presented in this study may be developed as a generic one for collecting or recycling the pollutant-loaded nano-sized absorbents. PMID:25966885

  13. AQUEOUS TWO-PHASE GAS FLOATATION SPECTROPHOTOMETRIC DETERMINATION OF TRACE TETRACYCLINE IN ENVIRONMENTAL WATER SAMPLE

    Institute of Scientific and Technical Information of China (English)

    HOU Yanmin; YAN Yongsheng; LI Chunxiang; ZHAO Xiaojun; WANG Liang

    2008-01-01

    A green method for separating and enriching trace tetracycline (TC) in environment water by Aqueous Two-phase Gas Fioatation Spectrophotometry has been proposed, the principium was discussed.In this paper, the hydrophobic complex composed of Mg(Ⅱ) and TC was floated into organic phase under the optimal conditions: pH=10, the floatatlon equipment is home-made, n-propyl alcohol as the organic solvent, sodium chloride as the separating phase reagent.The data were obtained by spectrophotometry after floatatlon; The linear regression ,equation is A=2.33×105 C(mol/L)+0.2179, linear range is from 3.77×107mol/L to 6.32×105mol/L, respectively, with the correlation coefficient (r) better than 0.9997, relative recoveries is 99.7% to 100.3%, limit of detection was 4.29×10-8mol/L, The method can be applied to analyse the trace TC in water sample, the result is better.

  14. Supercooling of aqueous dimethylsulfoxide solution at normal and high pressures: Evidence for the coexistence of phase-separated aqueous dimethylsulfoxide solutions of different water structures

    Science.gov (United States)

    Kanno, H.; Kajiwara, K.; Miyata, K.

    2010-05-01

    Supercooling behavior of aqueous dimethylsulfoxide (DMSO) solution was investigated as a function of DMSO concentration and at high pressures. A linear relationship was observed for TH (homogeneous ice nucleation temperature) and Tm (melting temperature) for the supercooling of aqueous DMSO solution at normal pressure. Analysis of the DTA (differential thermal analysis) traces for homogeneous ice crystallization in the bottom region of the TH curve for a DMSO solution of R =20 (R: moles of water/moles of DMSO) at high pressures supported the contention that the second critical point (SCP) of liquid water should exist at Pc2=˜200 MPa and at Tc2<-100 °C (Pc2: pressure of SCP, Tc2: temperature of SCP). The presence of two TH peaks for DMSO solutions (R =15, 12, and 10) suggests that phase separation occurs in aqueous DMSO solution (R ≤15) at high pressures and low temperatures (<-90 °C). The pressure dependence of the two TH curves for DMSO solutions of R =10 and 12 indicates that the two phase-separated components in the DMSO solution of R =10 have different liquid water structures [LDL-like and HDL-like structures (LDL: low-density liquid water, HDL: high-density liquid water)] in the pressure range of 120-230 MPa.

  15. How Is the Oxidative Capacity of the Cloud Aqueous Phase Modified By Bacteria?

    Science.gov (United States)

    Deguillaume, L.; Mouchel-Vallon, C.; Passananti, M.; Wirgot, N.; Joly, M.; Sancelme, M.; Bianco, A.; Cartier, N.; Brigante, M.; Mailhot, G.; Delort, A. M.; Chaumerliac, N. M.

    2014-12-01

    The aqueous phase photochemical reactions of constituents present in atmospheric water like H2O2, NO3-, NO2- and Fe(III) aqua-complexes or organic complexes can form radicals such as the hydroxyl radical HO within the water drop. However, the literature lacks of data precising the rate of HO formation and the relative contribution of the photochemical sources of HO. The production of radicals in cloud aqueous phase drives the oxidative capacity of the cloud medium and the efficiency of organic matter oxidation. The oxidation of organic compounds is suspected to lead to oxygenated species that could contribute to secondary organic aerosol (SOA) mass (Ervens et al., 2011). In current cloud chemistry models, HO concentrations strongly depend on the organic and iron amount. For high concentrations of organic compounds, this radical is efficiently consumed during the day due to the oxidation process. When iron concentrations are typical from continental cloud, the photolysis of Fe(III) complexes and the Fenton reaction drive the HO concentrations in the cloud models. The concept of biocatalysed reactions contributing to atmospheric chemistry as an alternative route to photochemistry is quite new (Vaïtilingom et al., 2013); it emerged from the recent discovery of metabolically active microorganisms in clouds. Microorganisms are well-known to degrade organic matter but they could also interact with oxidant species such as H2O2 (or their precursors) thanks to their oxidative and nitrosative stress metabolism that will act directly on these species and on their interactions with iron (metalloproteins and siderophores). For the moment, biological impact on radical chemistry within cloud has not been yet considered in cloud chemistry models. Bacterial activity will be introduced as catalysts in a multiphase cloud chemistry model using degradation rates measured in the laboratory. For example, biodegradation rates of the oxidants H2O2 by model bacteria will be tested in the

  16. A UNIVERSAL ANALYTIC POTENTIAL-ENERGY FUNCTION BASED ON A PHASE FACTOR

    Institute of Scientific and Technical Information of China (English)

    C.F. Yu; K. Yan; D.Z. Liu

    2006-01-01

    Using a field equation with a phase factor, a universal analytic potential-energy function applied to the interactions between diatoms or molecules is derived, and five kinds of potential curves of common shapes are obtained adjusting the phase factors. The linear thermal expansion coefficients and Young's moduli of eleven kinds of fuce-centered cubic (fcc) metals - Al, Cu, Ag, etc. Are calculated using the potential-energy function; the computational results are quite consistent with experimental values. Moreover, an analytic relation between the linear thermal expansion coefficients and Young's moduli of fcc metals is given using the potential-energy function. Finally, the force constants of fifty-five kinds of diatomic moleculars with low excitation state are computed using this theory, and they are quite consistent with RKR (Rydberg-Klein-Rees) experimental values.

  17. Instabilities Induced by Phase Fronts Coalescence During the Phase Transitions in a Thin Sma Layer: Mechanism and Analytical Descriptions

    CERN Document Server

    Dai, Hui-Hui

    2009-01-01

    Systematic experiments on stress-induced phase transitions in thin SMA structures in literature have revealed two interesting instability phenomena: the coalescence of two martensite-austenite fronts leads to a sudden stress drop and that of two austenite-martensite fronts leads to a sudden stress jump. In order to get an insight into these two phenomena, in this work we carry out an analytical study on the stress-induced phase transitions in a thin SMA layer (a simple structure in which the two coalescence processes can happen). We derive a quasi-2D model with a non-convex effective strain energy function while taking into account the rate-independent dissipation effect. By using a coupled series-asymptotic expansion method, we manage to express the total energy dissipation in terms of the leading-order term of the axial strain. The equilibrium equations are obtained by maximizing the total energy dissipation, which are then solved analytically under suitable boundary conditions. The analytical results revea...

  18. Method and apparatus for selective capture of gas phase analytes using metal .beta.-diketonate polymers

    Science.gov (United States)

    Harvey, Scott D [Kennewick, WA

    2011-06-21

    A process and sensor device are disclosed that employ metal .beta.-diketonate polymers to selectively capture gas-phase explosives and weaponized chemical agents in a sampling area or volume. The metal .beta.-diketonate polymers can be applied to surfaces in various analytical formats for detection of: improvised explosive devices, unexploded ordinance, munitions hidden in cargo holds, explosives, and chemical weapons in public areas.

  19. Phase behavior of ABC-type triple-hydrophilic block copolymers in aqueous solutions.

    Science.gov (United States)

    Zheng, Lingfei; Wu, Jianqi; Wang, Zheng; Yin, Yuhua; Jiang, Run; Li, Baohui

    2016-07-01

    The phase behavior of symmetric ABC triple-hydrophilic triblock copolymers in concentrated aqueous solutions is investigated using a simulated annealing technique. Two typical cases, in which the hydrophilicity of the middle B-block is either stronger or weaker than that of the end A- and C-blocks, are studied. In these two cases, a variety of phase diagrams are constructed as a function of the volume fraction of the B-block and the copolymer concentration ([Formula: see text] for both non-frustrated and frustrated copolymers. Structures, such as two-color alternatingly packed cylinders or gyroid, and lamellae-in-lamellae etc. that do not occur in the melt system, are obtained in solutions. Rich phase transition sequences, especially re-entrant phase transitions involving complex continuous networks of alternating gyroid and alternating diamond are observed for a given copolymer with decreasing [Formula: see text] . The difference in hydrophilicity among different blocks can result in inhomogeneous distribution of solvent molecules in the morphology, and with the decrease of [Formula: see text] , the distribution of solvent molecules presents a non-monotonic variation. This results in a non-monotonic variation of the effective volume fraction of each domain with the decrease of [Formula: see text] , which induces the re-entrant phase transitions. The presence of a good solvent for all the blocks can cause changes in the effective segregation strengths between different blocks and also in chain conformations, hence can alter the bulk phases and results in the occurrence of new structures and phase transitions. Especially, structures having A-C interfaces or A-C mixed domains can be obtained even in the non-frustrated copolymer systems, and structures obtained in the frustrated systems may be similar to those obtained in the non-frustrated systems. The window of the alternating gyroid structures may occupy a large part of the phase diagram for non

  20. A splitting technique for analytical modelling of two-phase multicomponent flow in porous media

    DEFF Research Database (Denmark)

    Pires, A.P.; Bedrikovetsky, P.G.; Shapiro, Alexander

    2006-01-01

    introduction of a potential associated with one of the conservation laws and its use as a new independent coordinate reduces the number of equations by one. The (n)x(n) conservation law model for two-phase n-component EOR flows in new coordinates is transformed into a reduced (n-1)x(n-1) auxiliary system...... problem, solution of one lifting hyperbolic equation and inversion of the coordinate transformation. The splitting allows proving the independence of phase transitions occurring during displacement of phase relative permeabilities and viscosities. For example, the minimum miscibility pressure (MMP) and...... containing just thermodynamical variables (equilibrium fractions of components, sorption isotherms) and one lifting equation containing just hydrodynamical parameters (phase relative permeabilities and viscosities). The algorithm to solve analytically the problem includes solution of the reduced auxiliary...

  1. Effects of organic solvents on the partitioning of enzymes in aqueous two-phase systems.

    Science.gov (United States)

    Johansson, G; Kopperschläger, G

    1987-02-13

    Organic solvents (ethylene glycol, glycerol, dimethyl sulphoxide, dimethylformamide, dioxane, methanol and propanol-2, as well as sucrose and urea) have been included in aqueous two-phase (liquid-liquid) systems comprised of water, dextran and poly(ethylene glycol). The concentration of the organic solvent was in most cases 20% (w/w). The influence of these solvents on the phase-forming properties, the volume ratio, the freezing point and the partitioning of a polymer-bound ligand, Procion Red HE-3B poly(ethylene glycol), has been studied. The partition coefficients for alkaline phosphatase decrease with ethylene glycol, glycerol, sucrose and urea (factors of 0.25-0.5), but increase with the other substances (factors of 1.2-1.6). The temperature effects on the partitioning of alkaline phosphatase from calf intestine as well as of phosphofructokinase from yeast in systems containing ethylene glycol have been studied and compared with partitioning in standard systems, not containing solvents. The possible uses of the above systems for partitioning studies of enzymes are discussed. PMID:2951391

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

    Energy Technology Data Exchange (ETDEWEB)

    Crouse, D. [Roy F. Weston, Inc., Edison, NJ (United States); Powell, G. [Environmental Protection Agency, Cincinnati, OH (United States); Hawthorn, S. [Environmental Protection Agency, Cincinnati, OH (United States); Weinstock, S. [Environmental Protection Agency, Butte, MT (United States)

    1997-12-31

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

  3. Evolution of phase and morphology of titanium dioxide induced from peroxo titanate complex aqueous solution.

    Science.gov (United States)

    Chang, Jeong Ah; Vithal, Muga; Baek, In Chan; Seok, Sang Il

    2010-01-01

    We demonstrate the growth of anatase TiO2 in nanospheres and rutile TiO2 in nanorods, by the hydrolysis of titanium tetraisopropoxide (TTIP) in the presence of hydrogen peroxide at 100 degrees C using sol-gel method. X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), and surface area measurement techniques are used to characterize the phase and shape developments of TiO2 obtained from peroxo titanate complex in an aqueous solution at 100 degrees C. Peroxo titanate complexes were prepared by a reaction of titanium hydroxide, formed by hydrolysis of titanium tetraisopropoxide (TTIP), and different amounts of hydrogen peroxide (H2O2). TEM and XRD investigations reveal that the size of spheres (anatase) and rods (rutile) are about 8 nm (diameter) and about 13 x 29 nm approximately 20 x 75 nm (width x length) respectively. The influence of molar ratio of H2O2/TTIP on the phase and morphology of TiO2 is presented. A mixture of anatase spheres and short rutile rods are formed at low H2O2/TTIP ratio while predominantly rutile a quit long rods are formed at higher H2O2/TTIP ratio. PMID:20352827

  4. Ionic Liquid-salt Aqueous Two-phase System, a Novel System for the Extraction of Abused Drugs

    Institute of Scientific and Technical Information of China (English)

    She Hong LI; Chi Yang HE; Hu Wei LIU; Ke An LI; Feng LIU

    2005-01-01

    A 1-butyl-3-methylimidazolium chloride-salt aqueous two-phase system was studied on extraction of abused drugs. The effects of sorts of salts, temperature, concentration of salt and drugs on system were investigated systematically. A satisfactory extraction efficiency of 93%was obtained for papaverine while that of morphine was 65%. The extraction mechanism was primarily discussed.

  5. Recovery of acetic acid from an aqueous pyrolysis oil phase by reactive extraction using tri-n-octylamine

    NARCIS (Netherlands)

    Rasrendra, C. B.; Girisuta, B.; van de Bovenkamp, H. H.; Winkelman, J. G. M.; Leijenhorst, E. J.; Venderbosch, R. H.; Windt, M.; Meier, D.; Heeres, H. J.

    2011-01-01

    The application of reactive extraction to isolate organic acids, particularly acetic acid, from the aqueous stream of phase splitted pyrolysis oil using a long chain aliphatic tertiary amine is reported. Acetic acid recovery was optimized by selecting the proper amine and diluent combination and adj

  6. Highly selective bimetallic Pt-Cu/Mg(Al)O catalysts for the aqueous-phase reforming of glycerol

    NARCIS (Netherlands)

    Boga, D.A.; Oord, R.; Beale, A.M.; Chung, Y.M.; Bruijnincx, P.C.A.; Weckhuysen, B.M.

    2013-01-01

    Monometallic Pt and bimetallic Pt-Cu catalysts supported on Mg(Al)O mixed oxides, obtained by calcination of the corresponding layered double hydroxides (LDHs), were prepared and tested in the aqueous-phase reforming (APR) of glycerol. The effect of the Mg/Al ratio and calcination temperature of the

  7. Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids

    Science.gov (United States)

    In most ecosystems, atmospheric deposition is the primary input of mercury. The total wet deposition of mercury in atmospheric chemistry models is sensitive to parameterization of the aqueous-phase reduction of divalent oxidized mercury (Hg2+). However, most atmospheric chemistry...

  8. A multiplex and straightforward aqueous phase immunoassay protocol through the combination of SERS-fluorescence dual mode nanoprobes and magnetic nanobeads.

    Science.gov (United States)

    Zong, Shenfei; Wang, Zhuyuan; Zhang, Ruohu; Wang, Chunlei; Xu, Shuhong; Cui, Yiping

    2013-03-15

    A novel aqueous phase immunoassay protocol was demonstrated, using surface enhanced Raman scattering (SERS)-fluorescence dual mode nanoprobes combined with magnetic nanobeads (MBs). Here, the dual mode nanoprobes provide an excellent multiplexing ability while the MBs greatly simplify the immunoassay process. Basically, the nanoprobes were acquired by assembling the Raman reporter tagged Au@Ag core-shell nanorods and quantum dots onto the silica nanospheres. When the specific antigens are presented in the immunoassay system containing antibody modified nanoprobes and MBs, the nanoprobes are captured by the MBs and further precipitated by a magnet. Consequently, both SERS and fluorescence signals are detected in the precipitates. Sandwich type immunoassay was conducted to examine the practicability of this protocol. Experimental results confirmed that the presented immunoassay protocol can accomplish highly specific and sensitive recognition of the target antigens. The detection limit was found out to be 0.1 pg/mL. We anticipate that high throughput bioanalysis can be fulfilled using the proposed immunoassay protocol, as the dual mode nanoprobes provide a great multiplexing capability while the MBs facilitate the convenient aqueous phase detection of the analytes. PMID:23084027

  9. A Novel Aqueous Two Phase System Composed of Surfactant and Xylitol for the Purification of Lipase from Pumpkin (Cucurbita moschata Seeds and Recycling of Phase Components

    Directory of Open Access Journals (Sweden)

    Mehrnoush Amid

    2015-06-01

    Full Text Available Lipase is one of the more important enzymes used in various industries such as the food, detergent, pharmaceutical, textile, and pulp and paper sectors. A novel aqueous two-phase system composed of surfactant and xylitol was employed for the first time to purify lipase from Cucurbita moschata. The influence of different parameters such as type and concentration of surfactants, and the composition of the surfactant/xylitol mixtures on the partitioning behavior and recovery of lipase was investigated. Moreover, the effect of system pH and crude load on the degree of purification and yield of the purified lipase were studied. The results indicated that the lipase was partitioned into the top surfactant rich phase while the impurities partitioned into the bottom xylitol-rich phase using an aqueous two phase system composed of 24% (w/w Triton X-100 and 20% (w/w xylitol, at 56.2% of tie line length (TLL, (TTL is one of the important parameters in this study and it is determined from a bimodal curve in which the tie-line connects two nodes on the bimodal, that represent concentration of phase components in the top and bottom phases and a crude load of 25% (w/w at pH 8.0. Recovery and recycling of components was also measured in each successive step process. The enzyme was successfully recovered by the proposed method with a high purification factor of 16.4 and yield of 97.4% while over 97% of the phase components were also recovered and recycled. This study demonstrated that the proposed novel aqueous two phase system method is more efficient and economical than the traditional aqueous two phase system method for the purification and recovery of the valuable enzyme lipase.

  10. A Novel Aqueous Two Phase System Composed of Surfactant and Xylitol for the Purification of Lipase from Pumpkin (Cucurbita moschata) Seeds and Recycling of Phase Components.

    Science.gov (United States)

    Amid, Mehrnoush; Manap, Mohd Yazid; Hussin, Muhaini; Mustafa, Shuhaimi

    2015-01-01

    Lipase is one of the more important enzymes used in various industries such as the food, detergent, pharmaceutical, textile, and pulp and paper sectors. A novel aqueous two-phase system composed of surfactant and xylitol was employed for the first time to purify lipase from Cucurbita moschata. The influence of different parameters such as type and concentration of surfactants, and the composition of the surfactant/xylitol mixtures on the partitioning behavior and recovery of lipase was investigated. Moreover, the effect of system pH and crude load on the degree of purification and yield of the purified lipase were studied. The results indicated that the lipase was partitioned into the top surfactant rich phase while the impurities partitioned into the bottom xylitol-rich phase using an aqueous two phase system composed of 24% (w/w) Triton X-100 and 20% (w/w) xylitol, at 56.2% of tie line length (TLL), (TTL is one of the important parameters in this study and it is determined from a bimodal curve in which the tie-line connects two nodes on the bimodal, that represent concentration of phase components in the top and bottom phases) and a crude load of 25% (w/w) at pH 8.0. Recovery and recycling of components was also measured in each successive step process. The enzyme was successfully recovered by the proposed method with a high purification factor of 16.4 and yield of 97.4% while over 97% of the phase components were also recovered and recycled. This study demonstrated that the proposed novel aqueous two phase system method is more efficient and economical than the traditional aqueous two phase system method for the purification and recovery of the valuable enzyme lipase. PMID:26091076

  11. Liquid-phase and evanescent-wave cavity ring-down spectroscopy in analytical chemistry.

    Science.gov (United States)

    van der Sneppen, L; Ariese, F; Gooijer, C; Ubachs, W

    2009-01-01

    Due to its simplicity, versatility, and straightforward interpretation into absolute concentrations, molecular absorbance detection is widely used in liquid-phase analytical chemistry. Because this method is inherently less sensitive than zero-background techniques such as fluorescence detection, alternative, more sensitive measurement principles are being explored. This review discusses one of these: cavity ring-down spectroscopy (CRDS). Advantages of this technique include its long measurement pathlength and its insensitivity to light-source-intensity fluctuations. CRDS is already a well-established technique in the gas phase, so we focus on two new modes: liquid-phase CRDS and evanescent-wave (EW)-CRDS. Applications of liquid-phase CRDS in analytical chemistry focus on improving the sensitivity of absorbance detection in liquid chromatography. Currently, EW-CRDS is still in early stages: It is used to study basic interactions between molecules and silica surfaces. However, in the future this method may be used to develop, for instance, biosensors with high specificity. PMID:20636052

  12. Teachable, high-content analytics for live-cell, phase contrast movies.

    Science.gov (United States)

    Alworth, Samuel V; Watanabe, Hirotada; Lee, James S J

    2010-09-01

    CL-Quant is a new solution platform for broad, high-content, live-cell image analysis. Powered by novel machine learning technologies and teach-by-example interfaces, CL-Quant provides a platform for the rapid development and application of scalable, high-performance, and fully automated analytics for a broad range of live-cell microscopy imaging applications, including label-free phase contrast imaging. The authors used CL-Quant to teach off-the-shelf universal analytics, called standard recipes, for cell proliferation, wound healing, cell counting, and cell motility assays using phase contrast movies collected on the BioStation CT and BioStation IM platforms. Similar to application modules, standard recipes are intended to work robustly across a wide range of imaging conditions without requiring customization by the end user. The authors validated the performance of the standard recipes by comparing their performance with truth created manually, or by custom analytics optimized for each individual movie (and therefore yielding the best possible result for the image), and validated by independent review. The validation data show that the standard recipes' performance is comparable with the validated truth with low variation. The data validate that the CL-Quant standard recipes can provide robust results without customization for live-cell assays in broad cell types and laboratory settings. PMID:20639505

  13. Analytical and experimental studies of an optimum multisegment phased liner noise suppression concept

    Science.gov (United States)

    Sawdy, D. T.; Beckemeyer, R. J.; Patterson, J. D.

    1976-01-01

    Results are presented from detailed analytical studies made to define methods for obtaining improved multisegment lining performance by taking advantage of relative placement of each lining segment. Properly phased liner segments reflect and spatially redistribute the incident acoustic energy and thus provide additional attenuation. A mathematical model was developed for rectangular ducts with uniform mean flow. Segmented acoustic fields were represented by duct eigenfunction expansions, and mode-matching was used to ensure continuity of the total field. Parametric studies were performed to identify attenuation mechanisms and define preliminary liner configurations. An optimization procedure was used to determine optimum liner impedance values for a given total lining length, Mach number, and incident modal distribution. Optimal segmented liners are presented and it is shown that, provided the sound source is well-defined and flow environment is known, conventional infinite duct optimum attenuation rates can be improved. To confirm these results, an experimental program was conducted in a laboratory test facility. The measured data are presented in the form of analytical-experimental correlations. Excellent agreement between theory and experiment verifies and substantiates the analytical prediction techniques. The results indicate that phased liners may be of immediate benefit in the development of improved aircraft exhaust duct noise suppressors.

  14. Experimental and Analytical Study of Lead-Bismuth-Water Direct Contact Boiling Two-Phase Flow

    Science.gov (United States)

    Novitrian; Dostal, Vaclav; Takahashi, Minoru

    The characteristics of lead-bismuth(Pb-Bi)-water boiling two-phase flow were investigated experimentally and analytically using a Pb-Bi-water direct contact boiling two-phase flow loop. Pb-Bi flow rates and void fraction were measured in a vertical circular tube at conditions of system pressure 7MPa, liquid metal temperature 460°C and injected water temperature 220°C. The drift-flux model with the assumption that bubble sizes were dependent on the fluid surface tension and the density ratio of Pb-Bi to steam-water mixture was chosen and modified by the best fit to the measured void fraction. Pb-Bi flow rates were analytically estimated using balance condition between buoyancy force and pressure losses, where the buoyancy force was calculated from void fraction estimated using the modified drift-flux model. The deviation of the analytical results of the flow rates from the experimental ones was less than 10%.

  15. Zirconium distribution between two phases: di-2-ethyl-hexyl phosphoric acid diluted in dodecane and aqueous phase of nitric acid

    International Nuclear Information System (INIS)

    Zirconium extraction by di-2-ethyl-hexyl phosphoric acid, from 0.5 to 10M nitric acid solutions is measured. The mechanism is independent of the acidity of the aqueous phase; a carbonic complex of zirconium nitrate is extracted. From a concentration 6M HNO3, an important extraction of nitric acid is noted. Consequences are brought out

  16. Polymers as Reference Partitioning Phase: Polymer Calibration for an Analytically Operational Approach To Quantify Multimedia Phase Partitioning.

    Science.gov (United States)

    Gilbert, Dorothea; Witt, Gesine; Smedes, Foppe; Mayer, Philipp

    2016-06-01

    Polymers are increasingly applied for the enrichment of hydrophobic organic chemicals (HOCs) from various types of samples and media in many analytical partitioning-based measuring techniques. We propose using polymers as a reference partitioning phase and introduce polymer-polymer partitioning as the basis for a deeper insight into partitioning differences of HOCs between polymers, calibrating analytical methods, and consistency checking of existing and calculation of new partition coefficients. Polymer-polymer partition coefficients were determined for polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs) by equilibrating 13 silicones, including polydimethylsiloxane (PDMS) and low-density polyethylene (LDPE) in methanol-water solutions. Methanol as cosolvent ensured that all polymers reached equilibrium while its effect on the polymers' properties did not significantly affect silicone-silicone partition coefficients. However, we noticed minor cosolvent effects on determined polymer-polymer partition coefficients. Polymer-polymer partition coefficients near unity confirmed identical absorption capacities of several PDMS materials, whereas larger deviations from unity were indicated within the group of silicones and between silicones and LDPE. Uncertainty in polymer volume due to imprecise coating thickness or the presence of fillers was identified as the source of error for partition coefficients. New polymer-based (LDPE-lipid, PDMS-air) and multimedia partition coefficients (lipid-water, air-water) were calculated by applying the new concept of a polymer as reference partitioning phase and by using polymer-polymer partition coefficients as conversion factors. The present study encourages the use of polymer-polymer partition coefficients, recognizing that polymers can serve as a linking third phase for a quantitative understanding of equilibrium partitioning of HOCs between any two phases. PMID:27115830

  17. Analytical Modeling Of The Steinmetz Coefficient For Single-Phase Transformer Eddy Current Loss Prediction

    Directory of Open Access Journals (Sweden)

    T. Aly Saandy

    2015-08-01

    Full Text Available Abstract This article presents to an analytical calculation methodology of the Steinmetz coefficient applied to the prediction of Eddy current loss in a single-phase transformer. Based on the electrical circuit theory the active power consumed by the core is expressed analytically in function of the electrical parameters as resistivity and the geometrical dimensions of the core. The proposed modeling approach is established with the duality parallel series. The required coefficient is identified from the empirical Steinmetz data based on the experimented active power expression. To verify the relevance of the model validations both by simulations with two in two different frequencies and measurements were carried out. The obtained results are in good agreement with the theoretical approach and the practical results.

  18. Analytical Energy Gradients in Range-Separated Hybrid Density Functional Theory with Random Phase Approximation

    CERN Document Server

    Mussard, Bastien; Ángyán, János G

    2015-01-01

    Analytical forces have been derived in the Lagrangian framework for several random phase approximation (RPA) correlated total energy methods based on the range separated hybrid (RSH) approach, which combines a short-range density functional approximation for the short-range exchange-correlation energy with a Hartree-Fock-type long-range exchange and RPA long-range correlation. The RPA correlation energy has been expressed as a ring coupled cluster doubles (rCCD) theory. The resulting analytical gradients have been implemented and tested for geometry optimization of simple molecules and intermolecular charge transfer complexes, where intermolecular interactions are expected to have a non-negligible effect even on geometrical parameters of the monomers.

  19. Analysis of Solid and Aqueous Phase Products from Hydrothermal Carbonization of Whole and Lipid-Extracted Algae

    Directory of Open Access Journals (Sweden)

    Amber Broch

    2013-12-01

    Full Text Available Microalgae have tremendous potential as a feedstock for production of liquid biofuels, particularly biodiesel fuel via transesterification of algal lipids. However, biodiesel production results in significant amounts of algal residues, or “lipid extracted algae” (LEA. Suitable utilization of the LEA residue will improve the economics of algal biodiesel. In the present study, we evaluate the hydrothermal carbonization (HTC of whole and lipid extracted algal (Spirulina maxima feedstocks in order to produce a solid biofuel (hydrochar and value-added co-products in the aqueous phase. HTC experiments were performed using a 2-L Parr reactor (batch type at 175–215 °C with a 30-min holding time. Solid, aqueous and gaseous products were analyzed using various laboratory methods to evaluate the mass and carbon balances, and investigate the existence of high value chemicals in the aqueous phase. The HTC method is effective in creating an energy dense, solid hydrochar from both whole algae and LEA at lower temperatures as compared to lignocellulosic feedstocks, and is effective at reducing the ash content in the resulting hydrochar. However, under the treatment temperatures investigated, less than 1% of the starting dry algae mass was recovered as an identified high-value chemical in the aqueous phase.

  20. Exploring Feasibility for Application of Luminescent CdTe Quantum Dots Prepared in Aqueous Phase to Live Cell Imaging

    Institute of Scientific and Technical Information of China (English)

    Ji Fang WENG; Xing Tao SONG; Liang LI; Hui Feng QIAN; Ke Ying CHEN; Xue Ming XU; Cheng Xi CAO; Ji Cun REN

    2006-01-01

    This paper explored the feasibility for the application of luminescent CdTe quantum dots prepared in aqueous phase to live cell imaging. The highly luminescent CdTe quantum dots (QDs)were first prepared in aqueous phase, and then were covalently coupled to a plant lectin (UEA-1),as a fluorescent probe. After incubating with of human umbilical vein endothelial cells (HUVECs), the QD probe with UEA-1 was able to specifically bind the corresponding cell receptor. The good cell images were obtained in live cells using laser confocal scanning microscopy. We predict that QDs prepared in water phase will probably become an attractive alternative probe in cellular imaging and bio-labeling.

  1. Multi-analyte approach for the determination of ng L{sup -1} levels of steroid hormones in unidentified aqueous samples

    Energy Technology Data Exchange (ETDEWEB)

    Noppe, H. [Ghent University, Faculty of Veterinary Medicine, Research group of Veterinary Public Health and Zoonoses, Laboratory of Chemical Analysis, Salisburylaan 133, B-9820 Merelbeke (Belgium)]. E-mail: Herlinde.Noppe@UGent.be; Verheyden, K. [Ghent University, Faculty of Veterinary Medicine, Research group of Veterinary Public Health and Zoonoses, Laboratory of Chemical Analysis, Salisburylaan 133, B-9820 Merelbeke (Belgium); Gillis, W. [Federal Agency for the Safety of the Food Chain, WTC III, Simon Bolivarlaan 30, B-1000 Brussels (Belgium); Courtheyn, D. [Federal Feed and Food Laboratory, Braemkasteelstraat 59, B-9050 Ghent (Belgium); Vanthemsche, P. [Federal Agency for the Safety of the Food Chain, WTC III, Simon Bolivarlaan 30, B-1000 Brussels (Belgium); De Brabander, H.F. [Ghent University, Faculty of Veterinary Medicine, Research group of Veterinary Public Health and Zoonoses, Laboratory of Chemical Analysis, Salisburylaan 133, B-9820 Merelbeke (Belgium)

    2007-03-14

    Since the 1970s, many analytical methods for the detection of illegal growth promoters, such as thyreostats, anabolics, {beta}-agonists and corticosteroids have been developed for a wide range of matrices of animal origin, including meat, fat, organ tissue, urine and faeces. The aim of this study was to develop an analytical method for the determination of ng L{sup -1} levels of estrogens, gestagens, androgens (EGAs) and corticosteroids in aqueous preparations (i.e. drinking water, drinking water supplements), commercially available on the 'black' market. For this, extraction was performed with Bakerbond C{sub 18} speedisk, a technique commonly used in environmental analysis. After fractionation, four fractions were collected using a methanol:water gradient program. Gas chromatography coupled to electron impact multiple mass spectrometry (GC-EI-MS{sup 2}) screening for the EGAs was carried out on the derivatized extracts. For the detection of corticosteroids, gas chromatography coupled to negative chemical ionization mass spectrometry (GC-NCI-MS) was used after oxidation of the extracts. Confirmation was done by liquid chromatography coupled to electrospray ionization multiple mass spectrometry (LC-ESI-MS{sup 2}). The combined use of GC and LC coupled to MS enabled the identification and quantification of anabolics and corticosteroids at the low ng L{sup -1} level. This study demonstrated the occurrence of both androgens and corticosteroids in different commercial aqueous samples.

  2. Adsorption and solid phase extraction of 8-hydroxyquinoline from aqueous solutions by using natural bentonite

    International Nuclear Information System (INIS)

    The nitrogen-heterocyclic compound 8-hydroxyquinoline (8HQ) is one of the components of coal tar and has a wide variety of uses in industry. Because of its toxicity for aquatic organisms and harmful effects for human health, the removal of 8HQ from aqueous solutions by adsorption onto natural bentonite was investigated in the present work. The experimental results show that the optimum pH value of 2.5 is favourable for the 8HQ adsorption. The experimental data were fitted well with the pseudo-second-order kinetic and Langmuir adsorption isotherm models at all studied temperatures. The maximum adsorption capacity obtained from the Langmuir isotherm model at 20 deg. C was 120.6 mg g-1. The calculated thermodynamic results such as ΔGo (-24.3 kJ mol-1) and ΔHo (-9.56 kJ mol-1) indicate that the adsorption process is spontaneous and exothermic in nature. Solid phase extraction of 8HQ was also performed. The X-ray diffractometry (XRD), Fourier Transform Infrared (FTIR) and thermogravimetric (TG) analyses were carried out in order to confirm the 8HQ adsorption onto bentonite. According to the obtained results, natural bentonite can be a reusable and effective adsorbent for the removal of 8HQ.

  3. Aqueous Two-phase Systems with Ultrasonic Extraction Used for Extracting Phenolic Compounds from Inonotus obliquus

    Institute of Scientific and Technical Information of China (English)

    ZHAO; Yan-xia; LIU; Yu-bing; LIU; Feng; ZHENG; Wei-fa

    2013-01-01

    Objective To optimize the extracting technology of assessing the maximum yield of phenolic compounds (PC) from Inonotus obliquus by single factor experiments and orthogonal array design methods through aqueous two-phase systems combined with ultrasonic extraction. Methods The range of the independent variables, namely levels of acetone and ammonium sulfate, and ultrasonic time were identified by a first set of single factor experiments. The actual values of the independent variables coded at four levels and three factors were selected based on the results of the single factor experiments. Subsequently, the levels of acetone and ammonium sulfate, and ultrasonic time were optimized using the orthogonal array method. Results The optimum conditions for the extraction of PC were found to use 7.0 mL acetone, 5.5 mg ammonium sulfate, with ultrasonic time for 5 min. Under these optimized conditions, the experimental maximum yield of PC was 37.8 mg/g, much higher than that of the traditional ultrasonic extraction (UE, 29.0 mg/g). And the PC obtained by this method had stronger anti-oxidative activities than those by traditional UE method. Conclusion These results indicate the suitability of the models developed and the success in optimizing the extraction conditions. This is an economical and efficient method for extracting polyphenols from I. obliquus.

  4. Aqueous Two-phase Systems with Ultrasonic Extraction Used for Extracting Phenolic Compounds from Inonotus obliquus

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yan-xia; LIU Yu-bing; LIU Feng; ZHENG Wei-fa

    2013-01-01

    Objective To optimize the extracting technology of assessing the maximum yield of phenolic compounds (PC)from Inonotus obliquus by single factor experiments and orthogonal array design methods through aqueous two-phase systems combined with ultrasonic extraction.Methods The range of the independent variables,namely levels of acetone and ammonium sulfate,and ultrasonic time were identified by a first set of single factor experiments.The actual values of the independent variables coded at four levels and three factors were selected based on the results of the single factor experiments.Subsequently,the levels of acetone and ammonium sulfate,and ultrasonic time were optimized using the orthogonal array method.Results The optimum conditions for the extraction of PC were found to use 7.0 mL acetone,5.5 mg ammonium sulfate,with ultrasonic time for 5 min.Under these optimized conditions,the experimental maximum yield of PC was 37.8 mg/g,much higher than that of the traditional ultrasonic extraction (UE,29.0 mg/g).And the PC obtained by this method had stronger anti-oxidative activities than those by traditional UE method.Conclusion These results indicate the suitability of the models developed and the success in optimizing the extraction conditions.This is an economical and efficient method for extracting polyphenols from Ⅰ.obliquus.

  5. Aqueous Phase Photo-Oxidation of Succinic Acid: Changes in Hygroscopic Properties and Reaction Products

    Science.gov (United States)

    Hudson, P. K.; Ninokawa, A.; Hofstra, J.; de Lijser, P.

    2013-12-01

    Atmospheric aerosol particles have been identified as important factors in understanding climate change. The extent to which aerosols affect climate is determined, in part, by hygroscopic properties which can change as a result of atmospheric processing. Dicarboxylic acids, components of atmospheric aerosol, have a wide range of hygroscopic properties and can undergo oxidation and photolysis reactions in the atmosphere. In this study, the hygroscopic properties of succinic acid aerosol, a non-hygroscopic four carbon dicarboxylic acid, were measured with a humidified tandem differential mobility analyzer (HTDMA) and compared to reaction products resulting from the aqueous phase photo-oxidation reaction of hydrogen peroxide and succinic acid. Reaction products were determined and quantified using gas chromatography-flame ionization detection (GC-FID) and GC-mass spectrometry (GC-MS) as a function of hydrogen peroxide:succinic acid concentration ratio and photolysis time. Although reaction products include larger non-hygroscopic dicarboxylic acids (e.g. adipic acid) and smaller hygroscopic dicarboxylic acids (e.g. malonic and oxalic acids), comparison of hygroscopic growth curves to Zdanovskii-Stokes-Robinson (ZSR) predictions suggests that the hygroscopic properties of many of the product mixtures are largely independent of the hygroscopicity of the individual components. This study provides a framework for future investigations to fully understand and predict the role of chemical reactions in altering atmospheric conditions that affect climate.

  6. Hydrogen production by aqueous-phase reforming of glycerol on supported noble metal catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Boonyanuwat, A.; Jentys, A.; Lercher, J.A. [Technische Univ. Muenchen, Garching (Germany). Dept. Chemie

    2006-07-01

    Hydrogen produced from renewable feedstocks such as crude glycerol, which is the main by-product formed during bio-diesel production, will develop into an attractive alternative energy source in the near future. A low temperature process is being developed using noble metal catalysts supported on gamma alumina. The overall catalytic activity of the catalysts Pt/Al{sub 2}O{sub 3}, Pd/Al{sub 2}O{sub 3}, Ni/Al{sub 2}O{sub 3}, Ru/Al{sub 2}O{sub 3} and Rh/Al{sub 2}O{sub 3} was studied. The activation energy decreased in the order: Pt>Pd>Ni>>Ru>Rh. The H{sub 2} selectivity of Pt was the highest and decreased for Pd > Ni > Ru > Rh. The H{sub 2} selectivity of Pt and Pd supported on gamma alumina was above 90%. The Pt/Al{sub 2}O{sub 3} catalyst showed a long term stability above 2 weeks using 1%wt glycerol in the feed, which indicates that these catalysts might have a high potential to be used for the aqueous phase reforming process of glycerol. (orig.)

  7. Adsorption and solid phase extraction of 8-hydroxyquinoline from aqueous solutions by using natural bentonite

    Science.gov (United States)

    Erdem, Bilge; Özcan, Adnan; Özcan, A. Safa

    2010-06-01

    The nitrogen-heterocyclic compound 8-hydroxyquinoline (8HQ) is one of the components of coal tar and has a wide variety of uses in industry. Because of its toxicity for aquatic organisms and harmful effects for human health, the removal of 8HQ from aqueous solutions by adsorption onto natural bentonite was investigated in the present work. The experimental results show that the optimum pH value of 2.5 is favourable for the 8HQ adsorption. The experimental data were fitted well with the pseudo-second-order kinetic and Langmuir adsorption isotherm models at all studied temperatures. The maximum adsorption capacity obtained from the Langmuir isotherm model at 20 °C was 120.6 mg g -1. The calculated thermodynamic results such as Δ G° (-24.3 kJ mol -1) and Δ H° (-9.56 kJ mol -1) indicate that the adsorption process is spontaneous and exothermic in nature. Solid phase extraction of 8HQ was also performed. The X-ray diffractometry (XRD), Fourier Transform Infrared (FTIR) and thermogravimetric (TG) analyses were carried out in order to confirm the 8HQ adsorption onto bentonite. According to the obtained results, natural bentonite can be a reusable and effective adsorbent for the removal of 8HQ.

  8. The effect of sulphates on partitioning of pectinases in aqueous two-phase systems

    Directory of Open Access Journals (Sweden)

    Antov Mirjana G.

    2004-01-01

    Full Text Available The effect of various sulphate salts on the partitioning of endo-pectinase and exo-pectinase in aqueous two-phase systems, composed of polyethylene glycol and dextran, was studied. Presence of ammonium sulphate and sodium sulphate at concentration 15 mmol/l in the system polyethylene glycol 4000/crude dextran, at tie-line length 7.44%, increased partition coefficient of endo-pectinase 1.25 and 1.2 fold, respectively. Ammonium sulphate at 15 mmol/l and sodium sulphate at 5 mmol/l enhanced partition coefficient for exo-pectinase for about 60% in comparison to the system without salts. Addition of magnesium and sodium sulphate to a final concentration of 0.3 mmol/l in the system containing polyethylene glycol 6000/dextran 500 000, at tie-line length 6.26%, increased the partition coefficient of endo activity for 95% and 32%, respectively. Both salts at the same concentration increased partition coefficient of exo activity 1.5 and 3 times, respectively, in comparison to the system without salts.

  9. Purification and characterization of polyphenol oxidase from waste potato peel by aqueous two-phase extraction.

    Science.gov (United States)

    Niphadkar, Sonali S; Vetal, Mangesh D; Rathod, Virendra K

    2015-01-01

    Potato peel from food industrial waste is a good source of polyphenol oxidase (PPO). This work illustrates the application of an aqueous two-phase system (ATPS) for the extraction and purification of PPO from potato peel. ATPS was composed of polyethylene glycol (PEG) and potassium phosphate buffer. Effect of different process parameters, namely, PEG, potassium phosphate buffer, NaCl concentration, and pH of the system, on partition coefficient, purification factor, and yield of PPO enzyme were evaluated. Response surface methodology (RSM) was utilized as a statistical tool for the optimization of ATPS. Optimized experimental conditions were found to be PEG1500 17.62% (w/w), potassium phosphate buffer 15.11% (w/w), and NaCl 2.08 mM at pH 7. At optimized condition, maximum partition coefficient, purification factor, and yield were found to be 3.7, 4.5, and 77.8%, respectively. After partial purification of PPO from ATPS, further purification was done by gel chromatography where its purity was increased up to 12.6-fold. The purified PPO enzyme was characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), followed by Km value 3.3 mM, and Vmax value 3333 U/mL, and enzyme stable ranges for temperature and pH of PPO were determined. These results revealed that ATPS would be an attractive option for obtaining purified PPO from waste potato peel. PMID:25036474

  10. Partitioning in aqueous two-phase systems: Analysis of strengths, weaknesses, opportunities and threats.

    Science.gov (United States)

    Soares, Ruben R G; Azevedo, Ana M; Van Alstine, James M; Aires-Barros, M Raquel

    2015-08-01

    For half a century aqueous two-phase systems (ATPSs) have been applied for the extraction and purification of biomolecules. In spite of their simplicity, selectivity, and relatively low cost they have not been significantly employed for industrial scale bioprocessing. Recently their ability to be readily scaled and interface easily in single-use, flexible biomanufacturing has led to industrial re-evaluation of ATPSs. The purpose of this review is to perform a SWOT analysis that includes a discussion of: (i) strengths of ATPS partitioning as an effective and simple platform for biomolecule purification; (ii) weaknesses of ATPS partitioning in regard to intrinsic problems and possible solutions; (iii) opportunities related to biotechnological challenges that ATPS partitioning may solve; and (iv) threats related to alternative techniques that may compete with ATPS in performance, economic benefits, scale up and reliability. This approach provides insight into the current status of ATPS as a bioprocessing technique and it can be concluded that most of the perceived weakness towards industrial implementation have now been largely overcome, thus paving the way for opportunities in fermentation feed clarification, integration in multi-stage operations and in single-step purification processes. PMID:26213222

  11. One-pot aqueous phase catalytic conversion of sorbitol to gasoline over nickel catalyst

    International Nuclear Information System (INIS)

    Highlights: • Directly production gasoline (C5–C12 alkanes) from biomass-derived sugar alcohol sorbitol. • Temperature of STG (553–593 K) was lower than that of traditional methanol to gasoline (MTG) (623–773 K). • Gasoline yield of 46.9% and C7–C12 hydrocarbons reached up to 45.5% in the gasoline products. - Abstract: The carbon chain extension and hydrodeoxygenation steps play critical roles in the high-energy-density hydrocarbons production. In this paper, a systematic study had been carried out to investigate one-pot aqueous phase catalytic conversion of sorbitol to gasoline (STG) over bifunctional Ni-based catalysts. Characterization technologies of N2 physisorption, X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and NH3 temperature-programmed desorption (NH3-TPD) were used to study the textural properties, phase compositions, acid behavior and morphologies of the catalysts. The catalytic performances were tested in a fixed bed reactor. It was found that the physically mixed Ni/HZSM-5 and Ni/silica-gel (mesoporous SG) catalyst realized the carbon chain extension and exhibited excellent performances on hydrodeoxygenation (HDO) reaction (46.9% of gasoline (C5–C12) yield and 45.5% of C7–C12 hydrocarbons in the gasoline products). Especially, the temperature of STG (553–593 K) was lower obviously than that of the traditional methanol to gasoline (MTG) process (623–773 K). It provided a novel transformation of sorbitol to long-chain alkanes by one-pot process over the bifunctional catalyst (Ni@HZSM-5/SG), wherein hydrodeoxygenation, ketonization and aldol condensation steps were integrated

  12. Extraction of amylase from fermentation broth in poly (Ethylene Glycol salt aqueous two-phase system

    Directory of Open Access Journals (Sweden)

    Raquel Pedrosa Bezerra

    2006-07-01

    Full Text Available Studies were carried out on the partition of amylase from Bacillus subtilis in a minimal medium at 37 ºC and 110 rpm. Enzyme recovery was carried out in aqueous two-phase system PEG-Phosphate salt were carried out. The best purification factor (5.4 was obtained in system PEG 1000 (16.7% w/w with potassium phosphate (14.8% w/w, at pH 6.0, resulting in a recovery of 45.2% activity enzymatic in the salt-rich phase.Enzimas amilolíticas têm sido amplamente investigadas com a finalidade de melhorar os processos industriais para a degradação do amido. Foi determinado que a extração da enzima em sistema bifásico aquosos é um método aplicável para separação e purificação de biomoléculas em misturas. Vários sistemas compostos de soluções aquosas de polietilenoglicol e fosfato foram avaliados. Estudos de produção em meio mínimo suplementado, à 37ºC, com uma velocidade de agitação de 110rpm e recuperação da amilase a partir do Bacillus subtilis em sistema bifásico aquoso PEG-fosfato foram avaliados. O melhor fator de purificação (5.4 foi obtido no sistema PEG 1000 (16.7% w/w com fosfato de potássio (14.8% w/w, a pH 6.0, resultando na recuperação da atividade enzimática de 45.2% na fase rica em sal.

  13. Semi-analytic variable charge solitary waves involving dust phase-space vortices (holes)

    Energy Technology Data Exchange (ETDEWEB)

    Tribeche, Mouloud; Younsi, Smain; Amour, Rabia; Aoutou, Kamel [Plasma Physics Group, Faculty of Sciences-Physics, Theoretical Physics Laboratory, University of Bab-Ezzouar, USTHB BP 32, El Alia, Algiers 16111 (Algeria)], E-mail: mtribeche@usthb.dz

    2009-09-15

    A semi-analytic model for highly nonlinear solitary waves involving dust phase-space vortices (holes) is outlined. The variable dust charge is expressed in terms of the Lambert function and we take advantage of this transcendental function to investigate the localized structures that may occur in a dusty plasma with variable charge trapped dust particles. Our results which complement the previously published work on this problem (Schamel et al 2001 Phys. Plasmas 8 671) should be of basic interest for experiments that involve the trapping of dust particles in ultra-low-frequency dust acoustic modes.

  14. Extraction and characterization of polysaccharides from Semen Cassiae by microwave-assisted aqueous two-phase extraction coupled with spectroscopy and HPLC.

    Science.gov (United States)

    Chen, Zhi; Zhang, Wei; Tang, Xunyou; Fan, Huajun; Xie, Xiujuan; Wan, Qiang; Wu, Xuehao; Tang, James Z

    2016-06-25

    A novel and rapid method for simultaneous extraction and separation of the different polysaccharides from Semen Cassiae (SC) was developed by microwave-assisted aqueous two-phase extraction (MAATPE) in a one-step procedure. Using ethanol/ammonium sulfate system as a multiphase solvent, the effects of MAATPE on the extraction of polysaccharides from SC such as the composition of the ATPS, extraction time, temperature and solvent-to-material ratio were investigated by UV-vis analysis. Under the optimum conditions, the yields of polysaccharides were 4.49% for the top phase, 8.80% for the bottom phase and 13.29% for total polysaccharides, respectively. Compared with heating solvent extraction and ultrasonic assisted extraction, MAATPE exhibited the higher extraction yields in shorter time. Fourier-transform infrared spectra showed that two polysaccharides extracted from SC to the top and bottom phases by MAATPE were different from each other in their chemical structures. Through acid hydrolysis and PMP derivatization prior to HPLC, analytical results by indicated that a polysaccharide of the top phases was a relatively homogeneous homepolysaccharide composed of dominant gucose glucose while that of the bottom phase was a water-soluble heteropolysaccharide with multiple components of glucose, xylose, arabinose, galactose, mannose and glucuronic acid. Molar ratios of monosaccharides were 95.13:4.27:0.60 of glucose: arabinose: galactose for the polysaccharide from the top phase and 62.96:14.07:6.67: 6.67:5.19:4.44 of glucose: xylose: arabinose: galactose: mannose: glucuronic acid for that from the bottom phase, respectively. The mechanism for MAATPE process was also discussed in detail. MAATPE with the aid of microwave and the selectivity of the ATPS not only improved yields of the extraction, but also obtained a variety of polysaccharides. Hence, it was proved as a green, efficient and promising alternative to simultaneous extraction of polysaccharides from SC. PMID

  15. A modular approach to the analytic calculation of spectral phase for grisms and other refractive/diffractive structures.

    Science.gov (United States)

    Durfee, Charles G; Squier, Jeff A; Kane, Steve

    2008-10-27

    Analytic expressions for spectral phase for optical systems are very important for the design of wide-bandwidth optical systems. We describe a general formalism for analytically calculating the spectral phase for arbitrary optical structure made up of nested pairs of plane-parallel interfaces that can be diffractive or refractive. Our primary application is the calculation of the spectral phase of a grism pair, which is then used to analyze the behavior of higher-order phase terms. The analytic expressions for the grism spectral phase provide insight into the tunability of the third-order phase of grisms as well as the fourth-order limits. Our exact and approximate expressions are compared with a raytracing model. PMID:18958079

  16. Discrimination between biologically relevant calcium phosphate phases by surface-analytical techniques

    International Nuclear Information System (INIS)

    The spatially resolved phase identification of biologically relevant calcium phosphate phases (CPPs) in bone tissue is essential for the elucidation of bone remodeling mechanisms and for the diagnosis of bone diseases. Analytical methods with high spatial resolution for the discrimination between chemically quite close phases are rare. Therefore the applicability of state-of-the-art ToF-SIMS, XPS and EDX as chemically specific techniques was investigated. The eight CPPs hydroxyapatite (HAP), β-tricalcium phosphate (β-TCP), α-tricalcium phosphate (α-TCP), octacalcium phosphate (OCP), dicalcium phosphate dihydrate (DCPD), dicalcium phosphate (DCP), monocalcium phosphate (MCP) and amorphous calcium phosphate (ACP) were either commercial materials in high purity or synthesized by ourselves. The phase purity was proven by XRD analysis. All of the eight CPPs show different mass spectra and the phases can be discriminated by applying the principal component analysis method to the mass spectrometric data. The Ca/P ratios of all phosphates were determined by XPS and EDX. With both methods some CPPs can be distinguished, but the obtained Ca/P ratios deviate systematically from their theoretical values. It is necessary in any case to determine a calibration curve, respectively the ZAF values, from appropriate standards. In XPS also the O(1s)-satellite signals are correlated to the CPPs composition. Angle resolved and long-term XPS measurements of HAP clearly prove that there is no phosphate excess at the surface. Decomposition due to X-ray irradiation has not been observed.

  17. Discrimination between biologically relevant calcium phosphate phases by surface-analytical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Kleine-Boymann, Matthias, E-mail: matthias.kleine-boymann@phys.chemie.uni-giessen.de; Rohnke, Marcus, E-mail: marcus.rohnke@phys.chemie.uni-giessen.de; Henss, Anja, E-mail: anja.henss@phys.chemie.uni-giessen.de; Peppler, Klaus, E-mail: klaus.peppler@phys.chemie.uni-giessen.de; Sann, Joachim, E-mail: joachim.sann@phys.chemie.uni-giessen.de; Janek, Juergen, E-mail: juergen.janek@phys.chemie.uni-giessen.de

    2014-08-01

    The spatially resolved phase identification of biologically relevant calcium phosphate phases (CPPs) in bone tissue is essential for the elucidation of bone remodeling mechanisms and for the diagnosis of bone diseases. Analytical methods with high spatial resolution for the discrimination between chemically quite close phases are rare. Therefore the applicability of state-of-the-art ToF-SIMS, XPS and EDX as chemically specific techniques was investigated. The eight CPPs hydroxyapatite (HAP), β-tricalcium phosphate (β-TCP), α-tricalcium phosphate (α-TCP), octacalcium phosphate (OCP), dicalcium phosphate dihydrate (DCPD), dicalcium phosphate (DCP), monocalcium phosphate (MCP) and amorphous calcium phosphate (ACP) were either commercial materials in high purity or synthesized by ourselves. The phase purity was proven by XRD analysis. All of the eight CPPs show different mass spectra and the phases can be discriminated by applying the principal component analysis method to the mass spectrometric data. The Ca/P ratios of all phosphates were determined by XPS and EDX. With both methods some CPPs can be distinguished, but the obtained Ca/P ratios deviate systematically from their theoretical values. It is necessary in any case to determine a calibration curve, respectively the ZAF values, from appropriate standards. In XPS also the O(1s)-satellite signals are correlated to the CPPs composition. Angle resolved and long-term XPS measurements of HAP clearly prove that there is no phosphate excess at the surface. Decomposition due to X-ray irradiation has not been observed.

  18. Studies on Pt–Mo phases using analytical techniques with high resolution

    Energy Technology Data Exchange (ETDEWEB)

    Topic, M., E-mail: mtopic@tlabs.ac.za [iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129 (South Africa); Khumalo, Z. [iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129 (South Africa); University of Cape Town, Physics Department, Private Bag X3, Rondebosch 7701 (South Africa); Pineda-Vargas, C.A. [iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129 (South Africa); Faculty of Health and Wellness Sciences, CPUT, Belville (South Africa)

    2014-01-01

    Pt–Mo coated system annealed at 1050 °C for 24 h was investigated using several analytical techniques with high resolution (SEM/EDX, μ-PIXE, RBS and XRD). These techniques provide structural and compositional data throughout the material depth and probing area. The results depend on the applied beam, its energy and size. They contribute to a better understanding of thermal annealing effects on the solid-state phase transformation and morphological changes in Pt–Mo coatings. The results indicate the presence of Pt- and Mo-solid solutions and two Pt–Mo phases (PtMo and Pt{sub 2}Mo{sub 3}), changes in the coating morphology, such as increased surface roughness and formation of “lace morphology”, as well as an increase in coating thickness.

  19. A semi-analytic model of the turbulent multi-phase interstellar medium

    CERN Document Server

    Braun, Harald

    2011-01-01

    We present a semi-analytic model for the interstellar medium that considers local processes and structures of turbulent star-forming gas. A volume element of the interstellar medium is described as a multiphase system, comprising a cold and a warm gas phase in effective (thermal plus turbulent) pressure equilibrium, and a stellar component. Since turbulence has a critical impact on the shape of the gaseous phases, on the production of molecular hydrogen and on the formation of stars, the consistent treatment of turbulence energy -- the kinetic energy of unresolved motions -- is an important new feature of our model. Besides turbulence production by supernovae and by the cooling instability, we also take into account the forcing by large scale motions. We formulate a set of ordinary differential equations, which statistically describes star formation and the exchange between the different budgets of mass and energy in a region of the interstellar medium with given mean density, size, metallicity and external t...

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

    Science.gov (United States)

    KANG, S.; Jeong, H. Y.

    2013-12-01

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

  1. Concurrence of aqueous and gas phase contamination of groundwater in the Wattenberg oil and gas field of northern Colorado.

    Science.gov (United States)

    Li, Huishu; Son, Ji-Hee; Carlson, Kenneth H

    2016-01-01

    The potential impact of rapid development of unconventional oil and natural gas resources using hydraulic fracturing and horizontal drilling on regional groundwater quality has received significant attention. Major concerns are methane or oil/gas related hydrocarbon (such as TPHs, BTEX including benzene, toluene, ethybenzene and xylene) leaks into the aquifer due to the failure of casing and/or stray gas migration. Previously, we investigated the relationship between oil and gas activity and dissolved methane concentration in a drinking water aquifer with the major finding being the presence of thermogenic methane contamination, but did not find detectable concentrations of TPHs or BTEX. To understand if aqueous and gas phases from the producing formation were transported concurrently to drinking water aquifers without the presence of oil/gas related hydrocarbons, the ionic composition of three water groups was studied: (1) uncontaminated deep confined aquifer, (2) suspected contaminated groundwater - deep confined aquifer containing thermogenic methane, and (3) produced water from nearby oil and gas wells that would represent aqueous phase contaminants. On the basis of quantitative and spatial analysis, we identified that the "thermogenic methane contaminated" groundwater did not have similarities to produced water in terms of ionic character (e.g. Cl/TDS ratio), but rather to the "uncontaminated" groundwater. The analysis indicates that aquifer wells with demonstrated gas phase contamination have not been contacted by an aqueous phase from oil and gas operations according to the methodology we use in this study and the current groundwater quality data from COGCC. However, the research does not prove conclusively that this the case. The results may provide insight on contamination mechanisms since improperly sealed well casing may result in stray gas but not aqueous phase transport. PMID:26519629

  2. Microbial side-chain cleavage of phytosterols by mycobacteria in vegetable oil/aqueous two-phase system.

    Science.gov (United States)

    Xu, Yang-Guang; Guan, Yi-Xin; Wang, Hai-Qing; Yao, Shan-Jing

    2014-09-01

    Microbial side-chain cleavage of natural sterols to 4-androstene-3,17-dione (AD) and 1,4-androstadiene-3,17-dione (ADD) by Mycobacteria has received much attention in pharmaceutical industry, while low yield of the reaction owing to the strong hydrophobicity of sterols is a tough problem to be solved urgently. Eight kinds of vegetable oils, i.e., sunflower, peanut, corn, olive, linseed, walnut, grape seed, and rice oil, were used to construct oil/aqueous biphasic systems in the biotransformation of phytosterols by Mycobacterium sp. MB 3683 cells. The results indicated that vegetable oils are suitable for phytosterol biotransformation. Specially, the yield of AD carried out in sunflower biphasic system (phase ratio of 1:9, oil to aqueous) was greatly increased to 84.8 % with 10 g/L feeding concentration after 120-h transformation at 30 °C and 200 rpm. Distribution coefficients of AD in different oil/aqueous systems were also determined. Because vegetable oils are of low cost and because of their eco-friendly characters, there is a great potential for the application of oil/aqueous two-phase systems in bacteria whole cell biocatalysis. PMID:25082765

  3. Rapid determination of alkylphenols in aqueous samples by in situ acetylation and microwave-assisted headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry.

    Science.gov (United States)

    Wu, Yu-Pei; Wang, Yu-Chen; Ding, Wang-Hsien

    2012-08-01

    A rapid and solvent-free procedure for the determination of 4-tert-octylphenol and 4-nonylphenol isomers in aqueous samples is described. The method involves in-situ acetylation and microwave-assisted headspace solid-phase microextraction prior to their determination using gas chromatography-ion trap mass spectrometry operated in the selected ion storage mode. The dual experimental protocols to evaluate the effects of various derivatization and extraction parameters were investigated and the conditions optimized. Under optimized conditions, 300 μL of acetic anhydride mixed with 1 g of potassium hydrogencarbonate and 2 g of sodium chloride in a 20 mL aqueous sample were efficiently extracted by a 65 μm polydimethylsiloxane-divinylbenzene fiber that was located in the headspace when the system was microwave irradiated at 80 W for 5 min. The limits of quantitation were 5 and 50 ng/L for 4-tert-octylphenol and 4-nonylphenol isomers, respectively. The precision for these analytes, as indicated by relative standard deviations, were less than 8% for both intra- and inter-day analysis. Accuracy, expressed as the mean extraction recovery, was between 74 to 88%. A standard addition method was used to quantitate 4-tert-octylphenol and 4-nonylphenol isomers, and the concentrations ranged from 120 to 930 ng/L in various environmental water samples. PMID:22899640

  4. Phase relation studies and thermo analytical analysis of melt quenched bscco glasses

    International Nuclear Information System (INIS)

    The Bi-2223 samples having nominal composition Bi/sub 1.6/ Pb/0.4/ Sr/sub 2/Ca/sub 2/Cu/sub 3/ O/sub 10/ were quenched from 1200 degree C, 1250 degree C and 1300 degree C to room temperature on brass, stainless steel, copper and bronze blocks. The samples were thermo analytically analyzed by differential thermal analyses (DTA) and Thermogravimetric Analysis (TGA). Activation energy, reaction rate constant and frequency factor for crystallization were evaluated employing different models. The precursors decomposed peritectically during melting, forming liquid and solid phases. Kinetic studies revealed that the thermal stability increases for the sample quenched from 1250 degree C. Resistivity measurement reveled that sample quenched on brass from 1250 degree C has highest value of critical temperature. X-ray diffraction results showed that major phase is high-Tc 2223 phase while low-Tc 2212 phase is also present in the samples. The change in structural and kinetic parameters could be ascribed to the oxygen diffusion behavior, resulting in hole carrier concentration. PACS Codes: 74.72 Hs; 67.80 Gb; 61.10 Nz. (author)

  5. Purification of C-phycocyanin from Spirulina platensis in aqueous two-phase systems using an experimental design

    OpenAIRE

    Francine Silva Antelo; Jorge Alberto Vieira Costa; Susana Juliano Kalil

    2015-01-01

    C-phycocyanin from Spirulina platensis was purified in aqueous two-phase systems (ATPS) of polyethylene glycol (PEG)/potassium phosphate, varying the molar mass of the PEG. Results using a full factorial design showed that an increase in the concentration of salt and decrease in the concentration of PEG caused an increment in the purification factor for all the ATPS studied. Optimization of the conditions of the purification was studied using a central composite rotatable design for each mola...

  6. Aqueous two-phase micellar systems in an oscillatory flow micro-reactor: Study of perspectives and experimental performance

    OpenAIRE

    A. M. LOPES; Silva, Daniel Pereira da; A.A. Vicente; Pessoa Júnior, Adalberto; Teixeira, J. A.

    2011-01-01

    Aqueous two-phase micellar systems (ATPMS) are micellar surfactant solutions with physical properties that make them very efficient for the extraction/concentration of biological products. In this work the main proposal that has been discussed is the possible applicability and importance of a novel oscillatory flow micro-reactor (micro-OFR) envisaged for parallel screening and/or development of industrial bioprocesses in ATPMS. Based on the technology of oscillatory flow mixing (OFM), this ba...

  7. Crystallization processes of hydrous metal oxides in the presence of aqueous-phase

    International Nuclear Information System (INIS)

    Evaluation of solubility-limiting solid is a central theme for predicting the rate of radionuclide release from HLW repository to the accessible environment. Such solids which control the concentration of radionuclide in subsurface water are considered to be sparingly soluble hydrous oxides. However, most of the hydrous oxides are thermodynamically unstable and alter from the amorphous form into crystal (oxyhydroxide or oxide), which, in turn, changes the solubility of radionuclide drastically. So far, such crystallization rates have been hardly clarified. This co-operative research focused on (1) the crystallization process from amorphous Fe(OH)3 to goethite, i.e., α-FeO(OH), and (2) the precipitation of Ce(III) or Ce(IV) and the chemical change in ageing. To begin with, the method to determine the crystallization fraction has been developed for the study. This method using TG(thermogravimetry)-curve quantifies the mole fraction of crystalline hydrous oxides, e.g., (Fe in goethite)/(total Fe in hydrous iron oxides precipitated). Using this method, the crystallization process of Fe(OH)3 was examined. The experimental parameters were the ageing time, pH-value, temperature, and dehydration methods. The results suggested that the aqueous phase plays an important role in changing the chemical structure into the crystal form. This tendency was observed also in the hydrous oxides of Ce(III) and Ce(IV). Further, the crystallization rate of Ce(OH)4 to CeO2 depended on the initial amount of CeO2 in ageing (although its amount of CeO2 was relatively small as compared to Ce(OH)4). These information will contribute to predicting the solubility-limiting solid in the performance assessment of HLW repository system. (author)

  8. Electrical resistivity for detecting subsurface non-aqueous phase liquids: A progress report

    International Nuclear Information System (INIS)

    Soils and groundwater have been contaminated by hazardous substances at many places in the United States and many other countries. The contaminants are commonly either petroleum products or industrial solvents with very low solubility in water. These contaminants are usually called non-aqueous phase liquids (NAPLs). The cost of cleaning up the affected sites in the United States is estimated to be of the order of 100 billion dollars. In spite of the expenditure of several billion dollars during the last 15 years, to date, very few, if any major contaminated site has been restored. The presence of NAPL pools in the subsurface is believed to be the main cause for the failure of previous cleanup activities. Due to their relatively low water solubility, and depending on their volume, it takes tens or even hundreds of years to deplete the NAPL sources if they are not removed from the subsurface. The intrinsic electrical resistivity of most NAPLs is typically in the range of 107 to 1012Ω-m, which is several orders of magnitude higher than that of groundwater containing dissolved solids (usually in the range of a few Ω-m to a few thousand Ω-m). Although a dry soil is very resistive, the electrical resistivity of a wet soil is on the order of 100 Ω-m and is dependent on the extent of water saturation. For a given soil, the electrical resistivity increases with decrease of water saturation. Therefore, if part of the pore water is replaced by a NAPL, the electrical resistivity will increase. At many NAPL sites, both the vadose and phreatic zones can be partially occupied by NAPL pools. It is the great contrast in electrical resistivity between the NAPLs and groundwater that may render the method to be effective in detecting subsurface NAPLs at contaminated sites. The following experiments were conducted to investigate the change of the electrical resistivity of porous media when diesel fuel (NAPL) replaces part of the water

  9. Analytical Evaluation of Two-Phase Natural Circulation Flow Under ERVC condition

    International Nuclear Information System (INIS)

    The process of two-phase natural circulation flow induced in the annular gap between the reactor vessel and the insulation under external reactor vessel cooling conditions was investigated analytically. HERMES-HALF experiments were performed to observe and quantify the induced two-phase natural circulation flow in the annular gap. A half-scaled non-heating experimental facility was designed by utilizing the results of a scaling analysis to simulate the APR1400 reactor and its insulation system. The behavior of the boiling-induced two-phase natural circulation flow in the annular gap was observed, and the liquid mass flow rates driven by the natural circulation loop and the void fraction distribution were measured. To complement the HERMES-HALF experimental effort, an analytical study of the dependence of the induced natural circulation mass flow rate on the inlet area and the volumetric air injection rate was performed using a loop integration of the momentum equation. The loop-integrated momentum equation was formulated in terms of the dimensionless mass flow rate and the area ratio. Asymptotic solutions were obtained for two limiting cases for which the dimensionless mass flow rate was either very large or very small. First-order approximate solution was also obtained and was found to agree with the experimental data within 20% in most situations. The natural circulation mass flow rate was found to increase as the water inlet area and the volumetric air injection rate were increased. For large inlet areas, the mass flow rate was found to depend almost linearly on the inlet area

  10. Exact analytical solution to three-dimensional phase change heat transfer problems in biological tissues subject to freezing

    Institute of Scientific and Technical Information of China (English)

    Fang-fang LI; Jing LIU; Kai YUE

    2009-01-01

    Analytically solving a three-dimensional (3-D) bioheat transfer problem with phase change during a freezing process is extremely difficult but theoretically important. The moving heat source model and the Green function method are introduced to deal with the cryopreservation process of in vitro biomaterials. Exact solutions for the 3-D temper-ature transients of tissues under various boundary conditions, such as totally convective cooling, totally fixed temperature cooling and a hybrid between them on tissue surfaces, are obtained. Furthermore, the cryosurgical process in living tissues subject to freezing by a single or multiple cryoprobes is also analytically solved. A closed-form analytical solution to the bioheat phase change process is derived by considering contributions from blood perfusion heat transfer, metabolic heat generation, and heat sink of a cryoprobe. The present method is expected to have significant value for analytically solving complex bioheat transfer problems with phase change.

  11. Chemical characterization of the main secondary organic aerosol (SOA products formed through aqueous-phase photonitration of guaiacol

    Directory of Open Access Journals (Sweden)

    Z. Kitanovski

    2014-04-01

    Full Text Available Guaiacol (2-methoxyphenol and its derivatives can be emitted into the atmosphere by thermal degradation (i.e. burning of wood lignins. Due to its volatility, guaiacol is predominantly distributed in the atmospheric gaseous phase. Recent studies have shown the importance of aqueous-phase reactions in addition to the dominant gas-phase and heterogeneous reactions of guaiacol, in the formation of secondary organic aerosol (SOA in the atmosphere. The main objectives of the present study were to chemically characterize the low-volatility SOA products of the aqueous-phase photonitration of guaiacol and examine their possible presence in urban atmospheric aerosols. The aqueous-phase reactions were carried out under simulated sunlight and in the presence of H2O2 and nitrite. The formed guaiacol reaction products were concentrated by using solid-phase extraction (SPE and then purified by means of semi-preparative high-performance liquid chromatography (HPLC. The fractionated individual compounds were isolated as pure solids and further analyzed with liquid-state 1H, 13C and 2D nuclear magnetic resonance (NMR spectroscopy and direct infusion negative ion electrospray ionization tandem mass spectrometry ((–ESI-MS/MS. The NMR and product ion (MS2 spectra were used for unambiguous product structure elucidation. The main products of guaiacol photonitration are 4-nitroguaiacol (4NG, 6-nitroguaiacol (6NG, and 4,6-dinitroguaiacol (4,6DNG. Using the isolated compounds as standards, 4NG and 4,6DNG were unambiguously identified in winter PM10 aerosols from the city of Ljubljana (Slovenia by means of HPLC/(–ESI-MS/MS. Owing to the strong absorption of UV and visible light, 4,6DNG could be an important constituent of atmospheric "brown" carbon, especially in regions affected by biomass burning.

  12. A Novel Aqueous Two Phase System Composed of Surfactant and Xylitol for the Purification of Lipase from Pumpkin (Cucurbita moschata) Seeds and Recycling of Phase Components

    OpenAIRE

    Mehrnoush Amid; Mohd Yazid Manap; Muhaini Hussin; Shuhaimi Mustafa

    2015-01-01

    Lipase is one of the more important enzymes used in various industries such as the food, detergent, pharmaceutical, textile, and pulp and paper sectors. A novel aqueous two-phase system composed of surfactant and xylitol was employed for the first time to purify lipase from Cucurbita moschata. The influence of different parameters such as type and concentration of surfactants, and the composition of the surfactant/xylitol mixtures on the partitioning behavior and recovery of lipase was invest...

  13. A new analytical model for conduction heating during the SAGD circulation phase

    Energy Technology Data Exchange (ETDEWEB)

    Duong, A.N. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[ConocoPhillips Canada Resources Corp., Calgary, AB (Canada); Tomberlin, T.A. [ConocoPhillips Canada Resources Corp., Calgary, AB (Canada); Cyrot, M. [Total E and P Canada Ltd., Calgary, AB (Canada)

    2008-10-15

    The steam assisted gravity drainage (SAGD) process has become the common procedure to recover bitumen from Alberta's oilsands. Inter-well communication must be initiated during the start-up phase of a SAGD process. The shape of an initial steam chamber that develops during the circulation phase influences the efficiency of bitumen recovery. As such, the heating conformance distributed along the horizontal wellbores must be well understood. The duration of the start-up phase varies with the characteristics of the oilsand formation and the distance between the wellbores, but it is typically a month to several months. This paper presented a newly developed analytical model that predicts the initial steam chamber. The model improves bitumen recovery efficiency by predicting the mid-point temperature front and heating efficiency of a wellpair during the SAGD circulation phase. The Excel-based model uses the exponential integral solution for radial heating in a long cylinder and superposition in space for multi-heating sources. It can predict the temperature profile if the steam temperatures or pressures are known during the circulation period. Wellbore modeling that includes any variation in distances between the wellbores is critical to both circulation time and heating conformance. This model has an advantage over numerical simulation in terms of reducing computational time and accurately modelling any variation in distance between wellbores. The results can be optimized under various operational conditions, wellbore profiles, tubing sizes and convection flow effects. This easy to use model is currently being used by ConocoPhillips Canada to optimize, predict and guide oilsands projects during the start-up phase of a SAGD process. 5 refs., 13 figs.

  14. Water-compatible dummy molecularly imprinted resin prepared in aqueous solution for green miniaturized solid-phase extraction of plant growth regulators.

    Science.gov (United States)

    Wang, Mingyu; Chang, Xiaochen; Wu, Xingyu; Yan, Hongyuan; Qiao, Fengxia

    2016-08-01

    A water-compatible dummy molecularly imprinted resin (MIR) was synthesized in water using melamine, urea, and formaldehyde as hydrophilic monomers of co-polycondensation. A triblock copolymer (PEO-PPO-PEO, P123) was used as porogen to dredge the network structure of MIR, and N-(1-naphthyl) ethylenediamine dihydrochloride, which has similar shape and size to the target analytes, was the dummy template of molecular imprinting. The obtained MIR was used as the adsorbent in a green miniaturized solid-phase extraction (MIR⬜mini-SPE) of plant growth regulators, and there was no organic solvent used in the entire MIR⬜mini-SPE procedure. The calibration linearity of MIR⬜mini-SPE⬜HPLC method was obtained in a range 5⬜250ngmL(↙1) for IAA, IPA, IBA, and NAA with correlation coefficient (r) Ⱕ0.9998. Recoveries at three spike levels are in the range of 87.6⬜100.0% for coconut juice with relative standard deviations Ⱔ8.1%. The MIR⬜mini-SPE method possesses the advantages of environmental friendliness, simple operation, and high efficiency, so it is potential to apply the green pretreatment strategy to extraction of trace analytes in aqueous samples. PMID:27378249

  15. An analytical study on the carrier-phase linear combinations for triple-frequency GNSS

    Science.gov (United States)

    Li, Jinlong; Yang, Yuanxi; He, Haibo; Guo, Hairong

    2016-08-01

    The linear combinations of multi-frequency carrier-phase measurements for Global Navigation Satellite System (GNSS) are greatly beneficial to improving the performance of ambiguity resolution (AR), cycle slip correction as well as precise positioning. In this contribution, the existing definitions of the carrier-phase linear combination are reviewed and the integer property of the resulting ambiguity of the phase linear combinations is examined. The general analytical method for solving the optimal integer linear combinations for all triple-frequency GNSS is presented. Three refined triple-frequency integer combinations solely determined by the frequency values are introduced, which are the ionosphere-free (IF) combination that the Sum of its integer coefficients equal to 0 (IFS0), the geometry-free (GF) combination that the Sum of its integer coefficients equal to 0 (GFS0) and the geometry-free and ionosphere-free (GFIF) combination. Besides, the optimal GF, IF, extra-wide lane and ionosphere-reduced integer combinations for GPS and BDS are solved exhaustively by the presented method. Their potential applications in cycle slip detection, AR as well as precise positioning are discussed. At last, a more straightforward GF and IF AR scheme than the existing method is presented based on the GFIF integer combination.

  16. Solubility measurements of (methane + ethane + propane) mixtures in the aqueous phase with gas hydrates under vapour unsaturated conditions

    International Nuclear Information System (INIS)

    Highlights: • The study focuses on mixed hydrates formed from a ternary hydrocarbon gas mixture. • Establish equilibrium conditions between mixed gas hydrate and aqueous phase, in the absence of the vapor phase. • Study the effect of temperature, pressure and salinity on the equilibrium concentrations of the dissolved gases. • Similar trends of measured and predicted concentrations of the dissolved gases with temperature, pressure, salinity. • Predicted concentrations were found systematically inferior to the measured ones. -- Abstract: The equilibrium concentrations of two ternary mixtures of methane, ethane and propane in the aqueous phase with gas hydrates were measured at pressures from 6 MPa to 20 MPa and temperatures from 274 K to 299 K at different salinity levels. These conditions for the gas mixtures selected were well inside the hydrate formation envelope so that the vapour phase could not coexist in equilibrium. A laboratory procedure was developed for the formation of homogeneous mixed hydrate crystals in the absence of a vapour phase. The compositional results generated in this work were compared against experimental data reported in the literature as well as against the predictions of the CSMGem thermodynamic model (Sloan and Koh, 2008; Ballard, 2002) [1,2

  17. Analytical Simulation of Flow and Heat Transfer of Two-Phase Nanofluid (Stratified Flow Regime

    Directory of Open Access Journals (Sweden)

    Mohammad Abbasi

    2014-01-01

    Full Text Available Nanofluids have evoked immense interest from researchers all around the globe due to their numerous potential benefits and applications in important fields such as cooling electronic parts, cooling car engines and nuclear reactors. An analytical study of fluid flow of in-tube stratified regime of two-phase nanofluid has been carried out for CuO, Al2O2, TiO3, and Au as applied nanoparticles in water as the base liquid. Liquid film thickness, convective heat transfer coefficient, and dryout length have been calculated. Among the considered nano particles, Al2O3 and TiO2 because of providing more amounts of heat transfer along with longer lengths of dryout found as the most appropriate nanoparticles to achieve cooling objectives.

  18. Composite ferric oxyhydroxide-containing phases formed in neutral aqueous solutions of tryptophan and indole-3-acetic acid

    International Nuclear Information System (INIS)

    Moessbauer, FTIR and XRD analyses showed that in aqueous medium in air in the presence of L-tryptophan (Trp) or indole-3-acetic acid (IAA) the ambient-temperature ageing of the precipitates formed from ferrous sulphate at pH ∼ 7 gave composite phases with varying proportions of γ-FeOOH (a dominating crystalline phase), α-FeOOH (both fine-grained, showing superparamagnetic behaviour at 298 K, and relatively better crystallized) and amorphous ferric hydroxide. The experimental data suggested a competition for adsorption sites at the oxyhydroxide surface in the suspension during phase transformations, as well as the transformation of γ-FeOOH (and/or amorphous ferric hydroxide) to α-FeOOH via the dissolution-reprecipitation mechanism. The formation of certain ferric oxyhydroxide phases in the presence of Trp and IAA - released e.g., in the course of bacterial and plant metabolism - can contribute to the regulation of soil mineral composition. (author)

  19. Behaviour of some compounds on interface and settling out into layers time of aqueous and organic phases

    International Nuclear Information System (INIS)

    Stability of oil-water and water-oil type emulsions in case of formation of structural and mechanical barrier phases on the interface, is studied. Investigation is conducted for systems which contain tributyl phosphate and its solutions in heptane as organic phase, and solutions of nitric acid, of silicic acid and of zirconium nitrate as aqueous phase. Time of emulsion stratification increases and can not be determined by physical properties of phases within the volume at presence of structural and mechanical barrier formed by polymeric forms od silicic acid. Additions of substances capable of formation of hydrogeneous bonds, prevent formation of stable extraction emulsions. At addition of dibutyl phosphoric acid slow stratification results from film formation on the interface consisting of oil-soluble zirconium dibutyl phosphates

  20. Study of Phase Separation of Poly(N-isopropylacrylamide-co-styrene) Aqueous Solutions with Rayleigh Scattering Technique

    Institute of Scientific and Technical Information of China (English)

    Yi Guobin; Zhu Zhenghong; Wang Fei; Chen Xudong; Yang Jin; Huang Yunwei

    2011-01-01

    A thermally sensitive copolymer, poly(N-isopropylacrylamfide-co-styrene) [P(NIPAM-co-St)] (Mn=9.5×105 g/mol and Mw/Mn= 1.51) was synthesized by soap-free emulsion polymerization. The phase separation of the co-polymer in water was investigated by Rayleigh scattering (RS) technique. The RS spectra revealed the transition of molecular conformation and the aggregation of molecular chains in the course of phase separation. The coil-to-globule and globule-to-coil transitions of P(NIPAM-co-St) chains were found in one heating-and-cooling cycle. By means of Avrami formula, apparent activation energy of phase separation of P(NIPAM-co-St) aqueous solutions was estimated. Moreover, a model was proposed to describe the phase separation process.

  1. Analytical electron microscope study of the omega phase transformation in a zirconium--niobium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zaluzec, N.J.

    1979-06-01

    An in-situ study of the as-quenched omega phase transformation in Zr--15% Nb was conducted between the temperatures of 77 and 300/sup 0/K using analytical electron microscopy. The domain size of the omega regions observed in this investigation was on the order of 30 A, consistent with previous observations in this system. No alignment of omega domains along <222> directions of the bcc lattice was observed and in-situ thermal cycling experiments failed to produce a long period structure of alternating ..beta.. and ..omega.. phase regions as predicted by one theory of this transformation. Several techniques of microstructural analysis were developed, refined, and standardized. Grouped under the general classification of Analytical Electron Microscopy (AEM) they provide the experimentalist with a unique tool for the microcharacterization of solids, allowing semiquantitative to quantitative analysis of the morphology, crystallography, elemental composition, and electronic structure of regions as small as 20 A in diameter. These techniques have complications, and it was necessary to study the AEM system used in this work so that instrumental artifacts which invalidate the information produced in the microscope environment might be eliminated. Once these factors had been corrected, it was possible to obtain a wealth of information about the microvolume of material under investigation. The microanalytical techniques employed during this research include: energy dispersive x-ray spectroscopy (EDS) using both conventional and scanning transmission electron microscopy (CTEM, STEM), transmission scanning electron diffraction (TSED), the stationary diffraction pattern technique, and electron energy loss spectroscopy (ELS) using a dedicated scanning transmission electron microscope (DSTEM).

  2. Fabrication of platinum nanoparticles in aqueous solution and solid phase using amphiphilic PB-b-PEO copolymer nanoreactors

    International Nuclear Information System (INIS)

    Graphical abstract: TEM image of Pt nanoparticles produced by reducing by NaBH4 within PB-b-PEO micelles in aqueous media (scale bar 1 nm). - Highlights: • Pt nanoparticles were synthesized within amphiphilic diblock copolymer micelles. • The effects of reducing agents and precursor dose on Pt np size were investigated. • The effect on fabrication of Pt np by reducing in aqueous and solid phases was compared. • The size of nanoparticles was about 1.4 nm for all doses and reducing agents types. - Abstract: Fabrication of Pt nanoparticles using an amphiphilic copolymer template in aqueous solution was achieved via polybutadiene-block-polyethyleneoxide copolymer micelles, which acted as nanoreactors. In addition, Pt nanoparticles were synthesized using hydrogen gas as the reducing agent in solid state for the first time to compare against solution synthesis. The influences of loaded precursor salt amount to micelles and the type of reducing agent on the size of nanoparticles were investigated through transmission electron microscopy. It was found that increasing the ratio of precursor salt to copolymer and using different type of reducing agent, even in solid phase reduction, did not affect the nanoparticle size. The average size of Pt nanoparticles was estimated to be 1.4 ± 0.1 nm. The reason for getting same sized nanoparticles was discussed in the light of nucleation, growth process, stabilization and diffusion of nanoparticles within micelles

  3. Fabrication of platinum nanoparticles in aqueous solution and solid phase using amphiphilic PB-b-PEO copolymer nanoreactors

    Energy Technology Data Exchange (ETDEWEB)

    Hoda, Numan, E-mail: nhoda@akdeniz.edu.tr [Department of Chemistry, Faculty of Sciences, Akdeniz University, 07058 Antalya (Turkey); Budama, Leyla; Çakır, Burçin Acar; Topel, Önder [Department of Chemistry, Faculty of Sciences, Akdeniz University, 07058 Antalya (Turkey); Ozisik, Rahmi [Department of Materials Science and Engineering and Renssleaer Nanotechnology Center, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    2013-09-01

    Graphical abstract: TEM image of Pt nanoparticles produced by reducing by NaBH{sub 4} within PB-b-PEO micelles in aqueous media (scale bar 1 nm). - Highlights: • Pt nanoparticles were synthesized within amphiphilic diblock copolymer micelles. • The effects of reducing agents and precursor dose on Pt np size were investigated. • The effect on fabrication of Pt np by reducing in aqueous and solid phases was compared. • The size of nanoparticles was about 1.4 nm for all doses and reducing agents types. - Abstract: Fabrication of Pt nanoparticles using an amphiphilic copolymer template in aqueous solution was achieved via polybutadiene-block-polyethyleneoxide copolymer micelles, which acted as nanoreactors. In addition, Pt nanoparticles were synthesized using hydrogen gas as the reducing agent in solid state for the first time to compare against solution synthesis. The influences of loaded precursor salt amount to micelles and the type of reducing agent on the size of nanoparticles were investigated through transmission electron microscopy. It was found that increasing the ratio of precursor salt to copolymer and using different type of reducing agent, even in solid phase reduction, did not affect the nanoparticle size. The average size of Pt nanoparticles was estimated to be 1.4 ± 0.1 nm. The reason for getting same sized nanoparticles was discussed in the light of nucleation, growth process, stabilization and diffusion of nanoparticles within micelles.

  4. Synthesis and characterization of conditioned carbon with iron nanoparticles for the arsenic removal in aqueous phase

    International Nuclear Information System (INIS)

    Using pineapple husks conditioned with carboxymethylcellulose, hexamine and ferric nitrate, a carbonaceous material was obtained with nanoparticles of Fe (C Fe), which was characterized and tested for arsenic removal in the aqueous phase. The microscopic study showed spheres 4 microns and filaments 100 nm wide, so as iron particles whose diameter decreases to an average of 38.81 nm, when pyrolysis time was increased to 180 min. their distribution in the carbonaceous matrix is homogeneous. According to energy dispersive X-ray spectroscopy, C Fe contains C (82.29%), O (7.23%), K (0.68%), Ca (3.77%) and Fe (6.25%) and its diffraction pattern shows the characteristic peak of Fe (0), which is not observed in the coal without iron. By neutron activation analysis were quantified Al, Br, Ce, Co, Cr, Cs, Eu, Hf, K, Mg, Mn, Na, Rb, Sb, Sc and Zn, they can be involved in the process of sorption of As (v) forming surface active sites. For C Fe and C B characterized by Fourier transform infrared spectrometry, groups C-H, C=O, C=C, -Nh, NH2, isocyanate and isonitrile were found, the last two were formed by the present hexamine. X-ray photoelectron spectroscopy showed energy states of C 1 and O 1 in pineapple shell washed, shell conditioned with iron, C Fe at different times and the pyrolysis coal without iron (C B). The material C Fe 180 presented a specific area of 167 m2/g and 7.12 ± 1 sites/nm2 isoelectric point while pHi = 11.1 C B is 98.80 m2/g specific area and 1.5 ± 1 sites/nm2 and pHi = 10.6, being favorable to the sorption process. The highest removal of As(v) for both materials was at ph = 2, fitting the kinetic data to pseudo-second order model. The isotherms as a function of concentration were adjusted to Freundlich model indicating multilayer chemisorption at specific sites of a heterogeneous medium. Characterization by scanning electron microscopy after the sample sorption Fe nanoparticles remain in the carbonaceous matrix being not affected by the agitation of

  5. Aqueous-phase photochemical oxidation and direct photolysis of vanillin - a model compound of methoxy phenols from biomass burning

    Science.gov (United States)

    Li, Y. J.; Huang, D. D.; Cheung, H. Y.; Lee, A. K. Y.; Chan, C. K.

    2014-03-01

    We present here experimental results on aqueous-phase (A) photochemical oxidation (with UV and OH radicals generated from H2O2 photolysis) and (B) direct photolysis (with only UV irradiation) of a methoxy phenol, vanillin (VL), as a model compound from biomass burning. Both on-line aerosol mass spectrometric (AMS) characterization and off-line chemical analyses were performed. AMS analyses of dried atomized droplets of the bulk reacting mixtures showed that VL almost entirely evaporates during the drying process. Large amounts of organic mass remained in the particle phase after reactions under both conditions. Under condition (A), AMS measured organic mass first increased rapidly and then decreased, attributable to the formation of non-volatile products and subsequent formation of smaller and volatile products, respectively. The oxygen-to-carbon (O : C) ratio of the products reached 1.5 after about 80 min, but dropped substantially thereafter. In contrast, organic mass increased slowly under condition (B). The O : C ratio reached 1.0 after 180 min. In off-line analyses, small oxygenates were detected under condition (A), while hydroxylated products and dimers of VL were detected under condition (B). Particle hygroscopic growth factor (GF) and cloud condensation nuclei (CCN) activity of the reacting mixtures were found to depend on both organic volume fraction and the degree of oxygenation of organics. Results show that (1) aqueous-phase processes can lead to the retention of a large portion of the organic mass in the particle phase; (2) once retained, this portion of organic mass significantly changes the hygroscopicity and CCN activity of the aerosol particles; (3) intensive photochemical oxidation gave rise to an O : C ratio as high as 1.5 but the ratio decreased as further oxidation led to smaller and more volatile products; and (4) polymerization occurred with direct photolysis, resulting in high-molecular-weight products of a yellowish color. This study

  6. Aqueous-phase photochemical oxidation and direct photolysis of vanillin - a model compound of methoxy-phenols from biomass burning

    Science.gov (United States)

    Li, Y. J.; Huang, D. D.; Cheung, H. Y.; Lee, A. K. Y.; Chan, C. K.

    2013-10-01

    We present here experimental results on aqueous-phase (A) photochemical oxidation (with UV and OH radicals generated from H2O2 photolysis) and (B) direct photolysis (with only UV irradiation) of a methoxy-phenol, vanillin (VL), as a model compound from biomass burning. Both on-line aerosol mass spectrometric (AMS) characterization and off-line chemical analyses were performed. AMS analyses of dried atomized droplets of the bulk reacting mixtures showed that VL almost entirely evaporates during the drying process. Large amounts of organic mass remained in the particle phase after reactions under both conditions. Under condition (A), AMS measured organic mass first increased rapidly and then decreased, attributable to the formation of non-volatile products and subsequent formation of smaller and volatile products, respectively. The oxygen-to-carbon (O:C) ratio of the products reached 1.5 after about 80 min, but dropped substantially thereafter. In contrast, organic mass increased slowly under condition (B). The O:C ratio reached 1.0 after 180 min. In off-line analyses, small oxygenates were detected under condition (A), while hydroxylated products and dimers of VL were detected under condition (B). Particle hygroscopic growth factor (GF) and cloud condensation nuclei (CCN) activity of the reacting mixtures were found to be dependent on both organic volume fraction and the degree of oxygenation of organics. Results show that (1) aqueous-phase processes can lead to the retention of a large portion of the organic mass in the particle phase; (2) once retained, this portion of organic mass significantly changes the hygroscopicity and CCN activity of the aerosol particles; (3) intensive photochemical oxidation gave rise to an O:C ratio as high as 1.5 but the ratio decreased as further oxidation led to smaller and more volatile products; and (4) polymerization occurred with direct photolysis, resulting in high-molecular-weight products of a yellowish color. This study

  7. Enhanced translocation and growth of Rhodococcus erythropolis PR4 in the alkane phase of aqueous-alkane two phase cultures were mediated by GroEL2 overexpression.

    Science.gov (United States)

    Takihara, Hayato; Ogihara, Jun; Yoshida, Takao; Okuda, Shujiro; Nakajima, Mutsuyasu; Iwabuchi, Noriyuki; Sunairi, Michio

    2014-01-01

    We previously reported that R. erythropolis PR4 translocated from the aqueous to the alkane phase, and then grew in two phase cultures to which long-chain alkanes had been added. This was considered to be beneficial for bioremediation. In the present study, we investigated the proteins involved in the translocation of R. erythropolis PR4. The results of our proteogenomic analysis suggested that GroEL2 was upregulated more in cells that translocated inside of the pristane (C19) phase than in those located at the aqueous-alkane interface attached to the n-dodecane (C12) surface. PR4 (pK4-EL2-1) and PR4 (pK4-ΔEL2-1) strains were constructed to confirm the effects of the upregulation of GroEL2 in translocated cells. The expression of GroEL2 in PR4 (pK4-EL2-1) was 15.5-fold higher than that in PR4 (pK4-ΔEL2-1) in two phase cultures containing C12. The growth and cell surface lipophilicity of PR4 were enhanced by the introduction of pK4-EL2-1. These results suggested that the plasmid overexpression of groEL2 in PR4 (pK4-EL2-1) led to changes in cell localization, enhanced growth, and increased cell surface lipophilicity. Thus, we concluded that the overexpression of GroEL2 may play an important role in increasing the organic solvent tolerance of R. erythropolis PR4 in aqueous-alkane two phase cultures. PMID:25311591

  8. An Analytical-Numerical Model for Two-Phase Slug Flow through a Sudden Area Change in Microchannels

    Directory of Open Access Journals (Sweden)

    A. Mehdizadeh Momen

    2016-01-01

    Full Text Available In this paper, two new analytical models have been developed to calculate two-phase slug flow pressure drop in microchannels through a sudden contraction. Even though many studies have been reported on two-phase flow in microchannels, considerable discrepancies still exist, mainly due to the difficulties in experimental setup and measurements. Numerical simulations were performed to support the new analytical models and to explore in more detail the physics of the flow in microchannels with a sudden contraction. Both analytical and numerical results were compared to the available experimental data and other empirical correlations. Results show that models, which were developed based on the slug and semi-slug assumptions, agree well with experiments in microchannels. Moreover, in contrast to the previous empirical correlations which were tuned for a specific geometry, the new analytical models are capable of taking geometrical parameters as well as flow conditions into account.

  9. Metal catalysts impregnated on porous media for aqueous phenol decomposition within three-phase fluidized-bed reactor

    International Nuclear Information System (INIS)

    Performance of metal catalysts to decompose aqueous phenol was experimentally investigated. Comparison of the phenol decomposition rates within three-phase fluidized-bed reactors utilizing only O3, TiO2 deposited on silica beads, metal catalyst (Ni or Co) impregnated on mesoporous carbon beads, or O3 in combination with each catalyst was thoroughly examined. It was found that the use of Co catalyst with the presence of O3 led to the best removal condition which aqueous phenol was completely decomposed within 10 min (k = 0.1944 min-1). In contrast, the use of TiO2 without O3 resulted in the worst decomposition of phenol (k = 0.0066 min-1). Some intermediate products, such as hydroquinone and catechol, were also detected but their final concentrations were negligibly low.

  10. Evidence of primary migration of condensate by molecular solution in aqueous phase in Yacheng Field, offshore South China

    Science.gov (United States)

    Quanxing, Zhang; Qiming, Zhang

    The composition of Yacheng condensate provides possible evidences of primary migration of petroleum by molecular solution in the aqueous phase. Aromatic hydrocarbons (HCs), especially benzene and toluene, make up a high percentage of the condensate. The abundance of each hydrocarbon (HC) in the condensate is mainly controlled by compound type and carbon number. The distribution of normal alkanes is discontinuous at C 16. Aromatic hydrocarbons are 3.8‰ isotopically heavier than the saturated hydrocarbons. The isoprenoid hydrocarbons are very abundant, especially pristane. The specific gravity of the Yacheng condensate is 0.85530 g cm -3, which is much higher than the average for condensates. These features are in good agreement with the HC solubilities in aqueous solution.

  11. Design and development of single stage purification of papain using Ionic Liquid based aqueous two phase extraction system and its Partition coefficient studies

    OpenAIRE

    Senthilkumar Rathnasamy; R.Kumaresan2

    2013-01-01

    As an emerging trend in bioseparation, aqueous two phase extractions based on phosponium ionic liquid have been utilized in this work to extract papain from Carica papaya fruit latex and the same wascompared with conventional aqueous two phase extraction system. Factors affecting the partition coefficient of papain such as ionic liquid concentration, pH of the extraction system and temperature have been investigated. The optimization studies show that ionic liquid concentrations and pH are ma...

  12. Aqueous two-phase systems: an efficient, environmentally safe and economically viable method for purification of natural dye carmine.

    Science.gov (United States)

    Mageste, Aparecida Barbosa; de Lemos, Leandro Rodrigues; Ferreira, Guilherme Max Dias; da Silva, Maria do Carmo Hespanhol; da Silva, Luis Henrique Mendes; Bonomo, Renata Cristina Ferreira; Minim, Luis Antonio

    2009-11-01

    Partition of the natural dye carmine has been studied in aqueous two-phase systems prepared by mixing aqueous solutions of polymer or copolymer with aqueous salt solutions (Na(2)SO(4) and Li(2)SO(4)). The carmine dye partition coefficient was investigated as a function of system pH, polymer molar mass, hydrophobicity, system tie-line length and nature of the electrolyte. It has been observed that the carmine partition coefficient is highly dependent on the electrolyte nature and pH of the system, reaching values as high as 300, indicating the high potential of the two-phase extraction with ATPS in the purification of carmine dye. The partition relative order was Li(2)SO(4)"Na(2)SO(4). Carmine molecules were concentrated in the polymer-rich phase, indicating an enthalpic specific interaction between carmine and the pseudopolycation, which is formed by cation adsorption along the macromolecule chain. When the enthalpic carmine-pseudopolycation interaction decreases, entropic forces dominate the natural dye-transfer process, and the carmine partitioning coefficient decreases. The optimization of the extraction process was obtained by a central composite face-centered (CCF) design. The CCF design was used to evaluate the influence of Li(2)SO(4) and PEO 1500 concentration and of the pH on the partition coefficient of carmine. The conditions that maximize the partition of carmine into the top phase were determined to be high concentrations of PEO and Li(2)SO(4) and low pH values within the ranges studied. PMID:19800067

  13. Multi-phase analytical model of radionuclide migration in lake water and bottom sediment system

    Energy Technology Data Exchange (ETDEWEB)

    Maceika, Evaldas; Filistovic, Vitold; Luksiene, Bena; Tarasiuk, Nikolay; Buivydas, Sarunas; Konstantinova, Marina; Puzas, Andrius [State research institute Center for Physical Sciences and Technology, Savanoriu ave. 231, LT-2300 Vilnius (Lithuania)

    2014-07-01

    Migration of long-lived radionuclides in lake eco-system is governed by several processes: advection, dilution, seasonal exchange, sedimentation; bioaccumulation. Interaction of dissolved radionuclide in water with the bottom sediments is of particular importance. Radionuclide can be adsorbed and desorbed by the bottom sediments. In turn, radionuclide is rapidly absorbed by organic and nonorganic origin particles in the lake water sphere. At the end, the particles will sink to the lake bottom and will form sediment layers of elevated contamination. Therefore explicit evaluation and balance of multi-phase radionuclide activity fluxes at the interface of lake water and bottom sediments surface is modelled in details. Created mathematical model, analytically describing dynamic of radionuclide migration, encompass both spheres of lake eco-system: water and bottom sediments. Solid and liquid radionuclide activity fractions are considered in every sphere. Sediment contamination is described by 1-D depth dependent advection-diffusion and adsorption/desorption reaction equation. Processes, taking place in the solid phase at the lake water sphere, are described by the adsorption/desorption dynamic equation as well as by activity fluxes balance at the interface with bottom sediments. Mathematical equations are rapidly solved by using Laplace transform and numerical inversion methods. Created model better described experimental measurement data of {sup 137}Cs radionuclide activity distribution profiles in studied lake bottom sediment vertical layers. This research was funded by a grant (No. MIP-041/2012) from the Research Council of Lithuania. (authors)

  14. Multi-phase analytical model of radionuclide migration in lake water and bottom sediment system

    International Nuclear Information System (INIS)

    Migration of long-lived radionuclides in lake eco-system is governed by several processes: advection, dilution, seasonal exchange, sedimentation; bioaccumulation. Interaction of dissolved radionuclide in water with the bottom sediments is of particular importance. Radionuclide can be adsorbed and desorbed by the bottom sediments. In turn, radionuclide is rapidly absorbed by organic and nonorganic origin particles in the lake water sphere. At the end, the particles will sink to the lake bottom and will form sediment layers of elevated contamination. Therefore explicit evaluation and balance of multi-phase radionuclide activity fluxes at the interface of lake water and bottom sediments surface is modelled in details. Created mathematical model, analytically describing dynamic of radionuclide migration, encompass both spheres of lake eco-system: water and bottom sediments. Solid and liquid radionuclide activity fractions are considered in every sphere. Sediment contamination is described by 1-D depth dependent advection-diffusion and adsorption/desorption reaction equation. Processes, taking place in the solid phase at the lake water sphere, are described by the adsorption/desorption dynamic equation as well as by activity fluxes balance at the interface with bottom sediments. Mathematical equations are rapidly solved by using Laplace transform and numerical inversion methods. Created model better described experimental measurement data of 137Cs radionuclide activity distribution profiles in studied lake bottom sediment vertical layers. This research was funded by a grant (No. MIP-041/2012) from the Research Council of Lithuania. (authors)

  15. Aqueous phase reforming of ethylene glycol - Role of intermediates in catalyst performance

    NARCIS (Netherlands)

    Vlieger, de D.J.M.; Mojet, B.L.; Lefferts, L.; Seshan, K.

    2012-01-01

    Liquid product formation during the aqueous catalytic reforming of ethylene glycol (EG) was studied up to 450 °C and 250 bar pressure. Methanol, ethanol, and acetic acid were the main liquid by-products during EG reforming in the presence of alumina-supported Pt and Pt–Ni catalysts. The effect of th

  16. Phosphate removal from aqueous phase using iron impregnated natural clay: kinetic and equilibrium modeling

    International Nuclear Information System (INIS)

    Even through phosphate is a major nutrient for plants and microorganisms, its excess amount (>1 ng/L) is often responsible for eutrophication of water bodies. Eutrophication is a phenomenon of algal booming causing high economic damage due to the death of tones of fishes. Therefore, nowadays, the removal of phosphate from aqueous solution and municipal sewage attains great concern. (Author)

  17. Conformation of lanthanides complexes of L-serine phosphate and ethanolamine phosphate in aqueous phase

    International Nuclear Information System (INIS)

    NMR paramagnetic shifts induced by rare earth cations lead to conformations of complexes in aqueous solution. A computer treatment is developped for complexes of L-serine phosphate and ethanolamine phosphate with lanthanides in acidic solution (pH=1 to 1.8). Angle and distance values are discussed with a hindered rotation about P-O1 bond

  18. Partition of synaptic membranes in aqueous two-phase systems at subzero temperatures by using anti-freeze solvent.

    Science.gov (United States)

    Johansson, G; Joelsson, M; Olde, B

    1990-11-16

    The freezing point of aqueous two-phase (liquid-liquid) systems containing water, dextran and poly(ethylene glycol) has been lowered by including glycerol. Biological membranes, obtained by fragmentation of a crude synaptosomal preparation from calf brain cortex, have been included in the two-phase systems. The effects of temperature and the concentration of glycerol on the partition of the membranes within the systems have been investigated. Considerable stabilisation of the membranes was noticed when they were partitioned at -10 degrees C compared with 0 degrees C. The influences of glycerol, ethylene glycol, N,N-dimethylformamide and tetrahydrofuran on the phase-forming properties of the systems and on enzyme activities are also presented. Possible use of the above systems for studies and separation of biological membranes are discussed. PMID:2245213

  19. The redox chemistry of neptunium in γ-irradiated aqueous nitric acid in the presence of an organic phase

    International Nuclear Information System (INIS)

    The radiolytic changes in oxidation state for solutions of initially Np(V) and/or Np(VI) were investigated by gamma-irradiation in conjunction with UV/Vis spectroscopy of the aqueous phase. Samples were irradiated in varying concentrations of nitric acid, and with or without the presence of 30 % TBP in dodecane. At short irradiation times Np(V) was oxidized to Np(VI), even in the presence of the organic phase. Upon the radiolytic production of sufficient amounts of nitrous acid, reduction of Np(VI) to Np(V) occurred in both phases. This was accompanied by stripping of the previously extracted Np(VI). Nitric acid concentrations of 6 M mitigated this reduction. (author)

  20. Analytical and experimental demonstration of depth of field extension for incoherent imaging system with a standard sinusoidal phase mask

    Institute of Scientific and Technical Information of China (English)

    Hui Zhao; Yingcai Li

    2012-01-01

    The wavefront coding technique is used to enlarge the depth of field (DOF) of incoherent imaging systems.The key to wavefront coding lies in the design of suitable phase masks. To date,numerous kinds of phase masks are proposed.However,further understanding is needed regarding phase mask with its phase function being in a standard sinusoidal form.Therefore,the characteristics of such a phase mask are studied in this letter.Deriving the defocused optical transfer function (OTF) analytically proves that the standard sinusoidal phase mask is effective in extending the DOF,and actual experiments confirm the numerical results.At the same time,with the Fisher information as a criterion,the standard sinusoidal phase mask shows a higher tolerance to focus errors (especially severe focus errors) than the classical cubic phase mask.%The wavefront coding technique is used to enlarge the depth of field (DOF) of incoherent imaging systems. The key to wavefront coding lies in the design of suitable phase masks. To date, numerous kinds of phase masks are proposed. However, further understanding is needed regarding phase mask with its phase function being in a standard sinusoidal form. Therefore, the characteristics of such a phase mask are studied in this letter. Deriving the defocused optical transfer function (OTF) analytically proves that the standard sinusoidal phase mask is effective in extending the DOF, and actual experiments confirm the numerical results. At the same time, with the Fisher information as a criterion, the standard sinusoidal phase mask shows a higher tolerance to focus errors (especially severe focus errors) than the classical cubic phase mask.

  1. Chelate-Modified Fenton Reaction for the Degradation of Trichloroethylene in Aqueous and Two-Phase Systems

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Scott [Univ of KY, dept of chemical and materials engineering; lynch, Andrew [Univ of KY, dept of chemical and materials engineering; Bachas, Leonidas [Univ of KY, Dept of Chemistry; hampson, Steve [Univ of KY Center for Applied Energy Research - KY Research Consortium of Energy and Environment; Ormsbee, Lindelle [Univ of KY Center for Applied Energy Research - KY Research Consortium of Energy and Environment; Bhattacharyya, Dibakar [Univ of KY, dept of chemical and materials engineering

    2008-06-01

    The Standard Fenton reaction has been used for In-Situ Chemical Oxidation (ISCO) of toxic organics in groundwater. However, it requires low pH operating conditions, and thus has limitations for in situ applications. In addition, hydroxyl radicals are rapidly consumed by hydroxyl scavengers found in the subsurface. These problems are alleviated through the chelate-modified Fenton (hydroxyl radical) reaction, which includes the addition of nontoxic chelate (L) such as citrate or gluconic acid. This chelate allows the reaction to take place at bear neutral pH and control hydrogen peroxide consumption by binding to Fe(II), forming an FeL complex. The chelate also binds to Fe(III), preventing its precipitation as ferric hydroxide and thus prevents problems associated with injection well plugging. The rate of TCE dechlorination in chelate-modified Fenton systems is a function of pH, H2O2 concentration, and FE:L ratio. The primary objective of this research is to model and apply this process to the destruction of trichloroethylene (TCE) present in both the aqueous and organic (in the form of droplets) phases. Experimentation proved the chelate-modified Fenton reaction effectively dechlorinates TCE in both the aqueous and organic phases at near-neutral pH. Other focuses of this work include determining the effect of [L]:[Fe] ratios on H2O2 and TCE degradation as well as reusability of the FE citrate solution under repeated H2O2 injections. Generalized models were developed to predict the concentration of TCE in the aqueous phase and TCE droplet radius as a function of time using established hydroxyl radial kinetics and mass transfer relationships.

  2. Key parameters controlling OH-initiated formation of secondary organic aerosol in the aqueous phase (aqSOA)

    Science.gov (United States)

    Ervens, Barbara; Sorooshian, Armin; Lim, Yong B.; Turpin, Barbara J.

    2014-04-01

    Secondary organic aerosol formation in the aqueous phase of cloud droplets and aerosol particles (aqSOA) might contribute substantially to the total SOA burden and help to explain discrepancies between observed and predicted SOA properties. In order to implement aqSOA formation in models, key processes controlling formation within the multiphase system have to be identified. We explore parameters affecting phase transfer and OH(aq)-initiated aqSOA formation as a function of OH(aq) availability. Box model results suggest OH(aq)-limited photochemical aqSOA formation in cloud water even if aqueous OH(aq) sources are present. This limitation manifests itself as an apparent surface dependence of aqSOA formation. We estimate chemical OH(aq) production fluxes, necessary to establish thermodynamic equilibrium between the phases (based on Henry's law constants) for both cloud and aqueous particles. Estimates show that no (currently known) OH(aq) source in cloud water can remove this limitation, whereas in aerosol water, it might be feasible. Ambient organic mass (oxalate) measurements in stratocumulus clouds as a function of cloud drop surface area and liquid water content exhibit trends similar to model results. These findings support the use of parameterizations of cloud-aqSOA using effective droplet radius rather than liquid water volume or drop surface area. Sensitivity studies suggest that future laboratory studies should explore aqSOA yields in multiphase systems as a function of these parameters and at atmospherically relevant OH(aq) levels. Since aerosol-aqSOA formation significantly depends on OH(aq) availability, parameterizations might be less straightforward, and oxidant (OH) sources within aerosol water emerge as one of the major uncertainties in aerosol-aqSOA formation.

  3. Linear free energy relationships between aqueous phase hydroxyl radical reaction rate constants and free energy of activation.

    Science.gov (United States)

    Minakata, Daisuke; Crittenden, John

    2011-04-15

    The hydroxyl radical (HO(•)) is a strong oxidant that reacts with electron-rich sites on organic compounds and initiates complex radical chain reactions in aqueous phase advanced oxidation processes (AOPs). Computer based kinetic modeling requires a reaction pathway generator and predictions of associated reaction rate constants. Previously, we reported a reaction pathway generator that can enumerate the most important elementary reactions for aliphatic compounds. For the reaction rate constant predictor, we develop linear free energy relationships (LFERs) between aqueous phase literature-reported HO(•) reaction rate constants and theoretically calculated free energies of activation for H-atom abstraction from a C-H bond and HO(•) addition to alkenes. The theoretical method uses ab initio quantum mechanical calculations, Gaussian 1-3, for gas phase reactions and a solvation method, COSMO-RS theory, to estimate the impact of water. Theoretically calculated free energies of activation are found to be within approximately ±3 kcal/mol of experimental values. Considering errors that arise from quantum mechanical calculations and experiments, this should be within the acceptable errors. The established LFERs are used to predict the HO(•) reaction rate constants within a factor of 5 from the experimental values. This approach may be applied to other reaction mechanisms to establish a library of rate constant predictions for kinetic modeling of AOPs. PMID:21410278

  4. Liquid-Liquid Equilibria of Aqueous Two-phase Systems Containing Polyethylene Glycol 4000 and Two Different Salts of Ammonium

    Directory of Open Access Journals (Sweden)

    G. Khayati

    2011-02-01

    Full Text Available The aim of this study was to survey on phase diagrams and Liquid-Liquid Equilibrium (LLE data of the aqueous PEG4000 - (NH42HPO4 and PEG4000 - (NH42SO4 systems experimentally at 298.15 K. The salting-out effect was also discussed on the basis of the Gibbs free energy of hydration of ions. The experimental binodal data were satisfactorily correlated with the Merchuk equation. Tie line compositions were correlated using the Othmer-Tobias and Bancroft equations, and the parameters have also reported. Good agreement was obtained with the experimental data with the model equations.

  5. Propeller-Like Nanorod-Upconversion Nanoparticle Assemblies with Intense Chiroptical Activity and Luminescence Enhancement in Aqueous Phase.

    Science.gov (United States)

    Wu, Xiaoling; Xu, Liguang; Ma, Wei; Liu, Liqiang; Kuang, Hua; Kotov, Nicholas A; Xu, Chuanlai

    2016-07-01

    Propeller-like nanoscale assemblies with exceptionally intense chiroptical activity and strong luminescence are prepared using gold nanorods and upconversion nanoparticles. The circular dichroism intensity of the tetramer reached 80.9 mdeg, with g-factor value of 2.1 × 10(-2) . The enhancement factor of upconversion luminescence is as high as 21.3 in aqueous phase. Attomolar bioanalysis of a cancer biomarker with two model is also achieved, showing potential for early disease diagnosis and environmental monitoring. PMID:27158947

  6. Analytical Estimation of Carrier Phase Recovery Approaches in Long-Haul High-Speed Optical Communication Systems

    CERN Document Server

    Xu, Tianhua

    2016-01-01

    The analytical study on the carrier phase estimation (CPE) approaches, involving a one-tap normalized least-mean-square (NLMS) algorithm, a block-wise average (BWA) algorithm, and a Viterbi-Viterbi (VV) algorithm has been investigated in the long-haul high-speed n-level phase shift keying (n-PSK) coherent optical fiber communication systems. The close-form predictions for the bit-error-rate (BER) performance have been derived and analyzed by considering both the intrinsic laser phase noise and the equalization enhanced phase noise (EEPN).

  7. Single step aqueous two-phase extraction for downstream processing of C-phycocyanin from Spirulina platensis.

    Science.gov (United States)

    Chethana, S; Nayak, Chetan A; Madhusudhan, M C; Raghavarao, K S M S

    2015-04-01

    C-phycocyanin, a natural food colorant, is gaining importance worldwide due to its several medical and pharmaceutical applications. In the present study, aqueous two-phase extraction was shown to be an attractive alternative for the downstream processing of C-phycocyanin from Spirulina platensis. By employing differential partitioning, C-phycocyanin selectively partitioned to the polymer rich (top) phase in concentrated form and contaminant proteins to the salt rich (bottom) phase. This resulted in an increase in the product purity (without losing much of the yield) in a single step without the need of multiple processing steps. Effect of process parameters such as molecular weight, tie line length, phase volume ratio, concentration of phase components on the partitioning behavior of C-phycocyanin was studied. The results were explained based on relative free volume of the phase systems. C-phycocyanin with a purity of 4.32 and yield of about 79 % was obtained at the standardized conditions. PMID:25829627

  8. Aqueous two-phase flotation for primary recovery of bacteriocin-like inhibitory substance (BLIS) from Pediococcus acidilactici Kp10.

    Science.gov (United States)

    Md Sidek, Nurul Lyana; Tan, Joo Shun; Abbasiliasi, Sahar; Wong, Fadzlie Wong Faizal; Mustafa, Shuhaimi; Ariff, Arbakariya B

    2016-08-01

    An aqueous two-phase flotation (ATPF) system based on polyethylene glycol (PEG) and sodium citrate (NaNO3C6H5O7·2H2O) was considered for primary recovery of bacteriocin-like inhibitory substance (BLIS) from Pediococcus acidilactici Kp10. The effects of ATPF parameters namely phase composition, tie-line length (TLL), volume ratio between the two phases (VR), amount of crude load (CL), pH, nitrogen gas flow rate (FR) and flotation time (FT) on the performance of recovery were evaluated. BLIS was mainly concentrated into the upper PEG-rich phase in all systems tested so far. The optimum conditions for BLIS purification, which composed of PEG 8000/sodium citrate, were: TLL of 42.6, VR of 0.4, CL of 22% (w/w), pH 7, average FT of 30min and FR of 20mL/min. BLIS was partially purified up to 5.9-fold with a separation efficiency of 99% under this optimal conditions. A maximum yield of BLIS activity of about 70.3% was recovered in the PEG phase. The BLIS from the top phase was successfully recovered with a single band in SDS-gel with molecular weight of about 10-15kDa. ATPF was found to be an effective technique for the recovery of BLIS from the fermentation broth of P. acidilactici Kp10. PMID:27262666

  9. Analytical model of the breakdown mechanism in a two-phase mixture

    International Nuclear Information System (INIS)

    A two-phase mixture (TPM) is a mixture of gas and macroparticles of high concentration. It is of interest in many different areas, such as in macroparticle-contaminated insulated systems, gas-liquid discharges, dusty plasmas and processing plasmas. Based on Townsend's theory, a physical model in analytical form for the breakdown mechanism in TPM is presented. In this model, two factors that influence the electron avalanche propagation are considered: macroparticles distorting the electric field and capture of the electrons. According to this breakdown mechanism and the dipole-enhanced model for calculating the maximum local field strength in TPM, the modified Paschen' law for TPM is presented to calculate the breakdown voltage. When the number of series of macroparticles (m) between two plate electrodes is very small, such as when m = 1, the breakdown voltage of the TPM is always lower than that of gas. With an increase in m or a decrease in the radius of macroparticles, the breakdown voltage tends to increase gradually for the same volume fraction of macroparticles. When m >> 1, the breakdown voltage of TPM may be lower or higher than that of gas, depending on the ratio of the number of saturation electrons captured by a macroparticle to the cell primary electrons generated at the cathode. Some other relevant factors, such as the volume fraction of macroparticles, the dielectric mismatch, the charging rate and the product of gas pressure and the gas length, are also discussed

  10. Analytical Model for Gyro-Phase Drift Arising from Abrupt Inhomogeneity

    Science.gov (United States)

    Walker, Jeffrey J.; Koepke, M. E.; Zimmerman, M. I.; Farrell, W. M.; Demidov, V. I.

    2013-01-01

    If a magnetized-orbit-charged grain encounters any abrupt inhomogeneity in plasma conditions during a gyro-orbit, such that the resulting in-situ equilibrium charge is significantly different between these regions (q(sub1)/q(sub 2) approximately 2, where q(sub 1) is the in-situ equilibrium charge on one side of the inhomogeneity, q(sub 2) is the in-situ equilibrium charge on the other side, and q(sub1) less than q(sub 2) less than 0), then the capacitive effects of charging and discharging of the dust grain can result in a modification to the orbit-averaged grain trajectory, i.e. gyro-phase drift. The special case of q(sub 1)/q(sub 2) is notioned for the purpose of illustrating the utility of the method. An analytical expression is derived for the grain velocity, assuming a capacitor approximation to the OML charging model. For cases in which a strong electric field suddenly appears in the wake or at the space-plasma-to-crater interface from solar wind and/or ultraviolet illumination and in which a magnetic field permeates an asteroid, comet, or moon, this model could contribute to the interpretation of the distribution of fields and particles.

  11. Analytical investigation of effect of fuel composition on the premixing phase of a steam explosion

    Energy Technology Data Exchange (ETDEWEB)

    Vierow, K. [Advanced Simulation Systems Department, Nuclear Power Engineering Corporation, Tokyo (Japan)

    2000-10-01

    In a hypothesized severe accident of a light water nuclear reactor, molten fuel may be released from the reactor pressure vessel and mix with a coolant pool in the lower regions of the containment vessel. If a suitable mixture is formed, an explosion may result in large pressure waves that impact and damage containment vessel structures. The purpose of this paper is to analytically study the effect of the molten fuel composition on the premixing phase with the VESUVIUS code. The JRC/Ispra KROTOS experiments, in particular, have shown that prototypic corium fuels are much less likely than alumina to form a pre-mixture that results in a steam explosion. In this paper, first, calculation results of three tests are compared against experimental data, Next, calculated spatial distributions of the fuel and void distributions for alumina and corium fuels and other detailed data that are not available experimentally are presented. These results are used to examine the fuel descent rates through the coolant pool, breakup characteristics, and other aspects of the fuel behaviors. Based on these results, insight is gained on the reasons for the relatively low potential of corium to form a favorable pre-explosion mixture. Finally, directions for future modeling efforts are summarized. (author)

  12. Multidimensional self-similar analytical solutions of two-phase flow in porous media

    Science.gov (United States)

    Fučík, Radek; Illangasekare, Tissa H.; Beneš, Michal

    2016-04-01

    In general, analytical solutions serve a useful purpose to obtain better insights and to verify numerical codes. For flow of two incompressible and immiscible phases in homogeneous porous media without gravity, one such method that neglects capillary pressure in the solution was first developed by Buckley and Leverett (1942). Subsequently, McWhorter and Sunada (1990) derived an exact solution for the one and two dimensional cases that factored in capillary effects. This solution used a similarity transform that allowed to reduce the governing equations into a single ordinary differential equation (ODE) that can be further integrated into an equivalent integral equation. We present a revision to McWhorter and Sunada solution by extending the self-similar solution into a general multidimensional space. Inspired by the derivation proposed by McWhorter and Sunada (1990), we integrate the resulting ODE in the third and higher dimensions into a new integral equation that can be subsequently solved iteratively by means of numerical integration. We developed implementations of the iterative schemes for one- and higher dimensional cases that can be accessed online on the authors' website.

  13. Cu determination in crude oil distillation products by atomic absorption and inductively coupled plasma mass spectrometry after analyte transfer to aqueous solution

    International Nuclear Information System (INIS)

    Cu was determined in a wide range of petroleum products from crude oil distillation using flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma mass spectrometry (ICP-MS). Different procedures of sample preparation were evaluated: (i) mineralization with sulfuric acid in an open system (ii) mineralization in a closed microwave system (iii) combustion in hydrogen-oxygen flame in the Wickbold's apparatus (iv) matrix evaporation followed by acid dissolution, and (v) acidic extraction. All the above procedures led to the transfer of the analyte into an aqueous solution for the analytical measurement step. It was found that application of FAAS was limited to the analysis of the heaviest petroleum products of high Cu content. In ICP-MS, the use of internal reference method (with Rh or In as internal reference element) was required to eliminate the matrix effects in the analysis of extracts and the concentrated solutions of mineralized heavy petroleum products. The detection limits (in original samples) were equal to, respectively, 10, 86, 3.3, 0.9 and 0.4 ng g-1 in procedures i-v with ETAAS detection and 10, 78, 1.1 and 0.5 ng g-1 in procedures i-iii and v with ICP-MS detection. The procedures recommended here were validated by recovery experiments, certified reference materials analysis and comparison of results, obtained for a given sample, in different ways. The Cu content in the analyzed samples was: 50-110 ng g-1 in crude oil, -1 in gasoline, -1 in atmospheric oil, -1 in heavy vacuum oil and 140-300 ng g-1 in distillation residue

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

    International Nuclear Information System (INIS)

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

  15. Design of functional guanidinium ionic liquid aqueous two-phase systems for the efficient purification of protein

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • A series of novel cationic functional hexaalkylguanidinium ionic liquids and anionic functional tetraalkylguanidinium ionic liquids have been synthesized. • Functional guanidinium ionic liquid aqueous two-phase systems have been first designed for the purification of protein. • Mechanisms and performances of the process were researched. • Simple, green, safety and presents better purified ability than ordinary process. • A potential efficient platform for protein purification and related studies. - Abstract: A series of novel cationic functional hexaalkylguanidinium ionic liquids and anionic functional tetraalkylguanidinium ionic liquids have been devised and synthesized based on 1,1,3,3-tetramethylguanidine. The structures of the ionic liquids (ILs) were confirmed by 1H nuclear magnetic resonance (1H NMR) and 13C nuclear magnetic resonance (13C NMR) and the production yields were all above 90%. Functional guanidinium ionic liquid aqueous two-phase systems (FGIL-ATPSs) have been first designed with these functional guanidinium ILs and phosphate solution for the purification of protein. After phase separation, proteins had transferred into the IL-rich phase and the concentrations of proteins were determined by measuring the absorbance at 278 nm using an ultra violet visible (UV–vis) spectrophotometer. The advantages of FGIL-ATPSs were compared with ordinary ionic liquid aqueous two-phase systems (IL-ATPSs). The proposed FGIL-ATPS has been applied to purify lysozyme, trypsin, ovalbumin and bovine serum albumin. Single factor experiments were used to research the effects of the process, such as the amount of ionic liquid (IL), the concentration of salt solution, temperature and the amount of protein. The purification efficiency reaches to 97.05%. The secondary structure of protein during the experimental process was observed upon investigation using UV–vis spectrophotometer, Fourier-transform infrared spectroscopy (FT

  16. Design of functional guanidinium ionic liquid aqueous two-phase systems for the efficient purification of protein

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Xueqin; Wang, Yuzhi, E-mail: wyzss@hnu.edu.cn; Zeng, Qun; Chen, Jing; Huang, Yanhua; Xu, Kaijia

    2014-03-01

    Graphical abstract: - Highlights: • A series of novel cationic functional hexaalkylguanidinium ionic liquids and anionic functional tetraalkylguanidinium ionic liquids have been synthesized. • Functional guanidinium ionic liquid aqueous two-phase systems have been first designed for the purification of protein. • Mechanisms and performances of the process were researched. • Simple, green, safety and presents better purified ability than ordinary process. • A potential efficient platform for protein purification and related studies. - Abstract: A series of novel cationic functional hexaalkylguanidinium ionic liquids and anionic functional tetraalkylguanidinium ionic liquids have been devised and synthesized based on 1,1,3,3-tetramethylguanidine. The structures of the ionic liquids (ILs) were confirmed by {sup 1}H nuclear magnetic resonance ({sup 1}H NMR) and 13C nuclear magnetic resonance (13C NMR) and the production yields were all above 90%. Functional guanidinium ionic liquid aqueous two-phase systems (FGIL-ATPSs) have been first designed with these functional guanidinium ILs and phosphate solution for the purification of protein. After phase separation, proteins had transferred into the IL-rich phase and the concentrations of proteins were determined by measuring the absorbance at 278 nm using an ultra violet visible (UV–vis) spectrophotometer. The advantages of FGIL-ATPSs were compared with ordinary ionic liquid aqueous two-phase systems (IL-ATPSs). The proposed FGIL-ATPS has been applied to purify lysozyme, trypsin, ovalbumin and bovine serum albumin. Single factor experiments were used to research the effects of the process, such as the amount of ionic liquid (IL), the concentration of salt solution, temperature and the amount of protein. The purification efficiency reaches to 97.05%. The secondary structure of protein during the experimental process was observed upon investigation using UV–vis spectrophotometer, Fourier-transform infrared

  17. Differential partition of virulent Aeromonas salmonicida and attenuated derivatives possessing specific cell surface alterations in polymer aqueous-phase systems

    Science.gov (United States)

    Van Alstine, J. M.; Trust, T. J.; Brooks, D. E.

    1986-01-01

    Two-polymer aqueous-phase systems in which partitioning of biological matter between the phases occurs according to surface properties such as hydrophobicity, charge, and lipid composition are used to compare the surface properties of strains of the fish pathogen Aeromonas salmonicida. The differential ability of strains to produce a surface protein array crucial to their virulence, the A layer, and to produce smooth lipopolysaccharide is found to be important in the partitioning behavior of Aeromonas salmonicida. The presence of the A layer is shown to decrease the surface hydrophilicity of the pathogen, and to increase specifically its surface affinity for fatty acid esters of polyethylene glycol. The method has application to the analysis of surface properties crucial to bacterial virulence, and to the selection of strains and mutants with specific surface characteristics.

  18. Distribution and speciation of cesium, strontium, and europium in the aqueous two-phase system milk-pectin

    International Nuclear Information System (INIS)

    Partition of radionuclides in aqueous liquid-liquid systems allows speciation of bioinorganic forms under nondenaturing conditions. From the fresh pasteurized skim bovine milk spiked with respective radionuclides and agitated with 4% w/w water solution of apple pectin, about 80% of cesium, 22% of strontium and less than 1.5% of europium is recovered with the pectin, phase at an initial milk - pectin volume ratio of 7:3. This recovery fraction is proportional to the abundance of radionuclides in milk serum. No protein bound fraction of strontium extractable by Aerosol OT in isooctane was obtained. More than 3-fold preconcentration of strontium and europium radionuclides in milk is achieved after 10-15 min membraneless osmosis with pectin phase. (author) 26 refs.; 6 tabs

  19. Morphological and phase evolution of TiO 2 nanocrystals prepared from peroxotitanate complex aqueous solution: Influence of acetic acid

    Science.gov (United States)

    Chang, Jeong Ah; Vithal, Muga; Baek, In Chan; Seok, Sang Il

    2009-04-01

    Nanosized anatase and rutile TiO 2 having different shape, phase and size have been prepared from aqueous solutions of peroxo titanium complex starting from titanium(IV) isopropoxide (TTIP), acetic acid and hydrogen peroxide (H 2O 2) in water/isopropanol media by a facile sol-gel process. The TiO 2 nanocrystals are characterized by powder X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, TEM, high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) techniques. The influence of pH and the sequence of addition of reaction contents on the phase and morphology of TiO 2 are studied. The reasons for the observation of only anatase and/or mixture of anatase and rutile are given.

  20. A Simple and Fast Aqueous-Phase Synthesis of Ultra-Highly Concentrated Silver Nanoparticles and Their Catalytic Properties.

    Science.gov (United States)

    Shahzad, Aasim; Chung, Minsub; Yu, Taekyung; Kim, Woo-Sik

    2015-11-01

    A simple and fast synthetic route to ultra-highly concentrated silver nanoparticles with long-term stability by reducing AgNO3 with ascorbic acid in the presence of polyethyleneimine (PEI) as a stabilizer in an aqueous phase is reported. The concentration of silver precursor was as high as 2000 mm (200 g of Ag nanoparticle per liter of water) and the reaction time was less than 10 min. The resulting silver nanoparticles show long-term stability after two months of storage at room temperature without any signs of particle aggregation or precipitation in an aqueous phase. The successful ligand exchange of PEI-stabilized silver nanoparticles to polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) without particle aggregation is also demonstrated. In addition, the catalytic activities of silver nanoparticles stabilized by various stabilizers prepared by the ligand exchange method was investigated. The PEI-stabilized silver nanoparticles exhibited a higher stability than those of PEG- and PVP-stabilized silver nanoparticles in the diffusion-controlled catalytic reduction of 4-nitrophenol to 4-aminophenol by NaBH4 . PMID:26324024

  1. Structure-activity relationship for the estimation of OH-oxidation rate constants of carbonyl compounds in the aqueous phase

    Directory of Open Access Journals (Sweden)

    J. F. Doussin

    2013-06-01

    Full Text Available In the atmosphere, one important class of reactions occurs in the aqueous phase in which organic compounds are known to undertake oxidation towards a number of radicals, among which OH radicals are the most reactive oxidants. In 2008, Monod and Doussin have proposed a new structure activity relationship (SAR to calculate OH-oxidation rate constants in the aqueous phase. This estimation method is based on the group-additivity principle and was until now limited to alkanes, alcohols, acids, bases and related polyfunctional compounds. In this work, the initial SAR is extended to carbonyl compounds, including aldehydes, ketones, dicarbonyls, hydroxy-carbonyls, acidic carbonyls, their conjugated bases, and the hydrated form of all these compounds. To do so, only five descriptors have been added and none of the previously attributed descriptors were modified. This extension leads now to a SAR which is based on a database of 102 distinct compounds for which 252 experimental kinetic rate constants have been gathered and reviewed. The efficiency of this updated SAR is such that 58% of the rate constants could be calculated within ±20% of the experimental data and 76% within ±40%.

  2. Steam-Enhanced Extraction Experiments, Simulations and Field Studies for Dense Non-Aqueous Phase Liquid Removal: A Review

    Directory of Open Access Journals (Sweden)

    Azizan Nor Asni

    2016-01-01

    Full Text Available Experiments, simulations and field studies for dense non-aqueous phase liquid (DNAPL removal have demonstrated successful recovery through steam-enhanced extraction. Steam-enhanced extraction is an innovative technology for soil and groundwater remediation to remove as much contamination as possible. Most of researchers study the main DNAPL recovery mechanisms such as physical displacement by vaporization, evaporation and condensation, reduction in interfacial tension and DNAPL viscosity influenced by temperature. Other removal mechanism such as steam distillation and steam stripping also has been studied. The removal of DNAPL using steam-enhanced extraction shall be investigated to identify, acquire, analyze, visualize, and evaluate the effectiveness of the remediation. Several parameters can be controlled to justify the successful of the remediation. A comprehensive understanding of the subsurface environment, multiphase fluid flow and the physical processes is required to prevent remediation failure. Thus, it will avoid continuous contamination of the subsurface environment. The researcher can quantify the reduction in contamination remediation and acquire high quality data sets to validate future numerical model. Aim of this paper is to review and to summarize the existing laboratory experiment, simulations and field studies from other researchers regarding steam-enhanced extraction for dense non-aqueous phase liquid removal.

  3. Effect of biochar addition on hydrogen and methane production in two-phase anaerobic digestion of aqueous carbohydrates food waste.

    Science.gov (United States)

    Sunyoto, Nimas M S; Zhu, Mingming; Zhang, Zhezi; Zhang, Dongke

    2016-11-01

    Effect of biochar addition on hydrogen and methane production in two-phase anaerobic digestion of aqueous carbohydrates was studied using bench-scale bioreactors. The cultures with biochar additions were placed in 100ml reactors and incubated at 35°C and pH 5 for hydrogen production. The residual cultures were then used for methane production, incubated at 35°C and pH 7. Daily yields of hydrogen and methane and weekly yield of volatile fatty acids (VFA) were measured. The hydrogen and methane production potentials, rate and lag phases of the two phases were analysed using the Gompertz model. The results showed that biochar addition increased the maximum production rates of hydrogen by 32.5% and methane 41.6%, improved hydrogen yield by 31.0% and methane 10.0%, and shortened the lag phases in the two phases by 36.0% and 41.0%, respectively. Biochar addition also enhanced VFA generation during hydrogen production and VFA degradation in methane production. PMID:27474855

  4. Derivatisation/solid-phase microextraction followed by gas chromatography-mass spectrometry for the analysis of phenoxy acid herbicides in aqueous samples

    DEFF Research Database (Denmark)

    Nilsson, Torben; Baglio, Daniela; Galdo-Miguez, Isabel;

    1998-01-01

    Different combinations of derivatisation and solid-phase microextraction followed by gas chromatography-mass spectrometry were optimised and evaluated for the analysis of phenoxy acid herbicides in water. The most successful derivatisation approach was aqueous-phase derivatisation with benzyl...

  5. Temperature-induced phase separation and hydration in poly(N-vinylcaprolactam) aqueous solutions: a study by NMR and IR spectroscopy, SAXS, and quantum-chemical calculations

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Dybal, Jiří; Starovoytova, Larisa; Zhigunov, Alexander; Sedláková, Zdeňka

    2012-01-01

    Roč. 8, č. 22 (2012), s. 6110-6119. ISSN 1744-683X R&D Projects: GA ČR GA202/09/1281 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : phase separation * coil-globule phase transition * aqueous solution Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.909, year: 2012

  6. Liquid-liquid equilibrium of water + PEG 8000 + magnesium sulfate or sodium sulfate aqueous two-phase systems at 35°C: experimental determination and thermodynamic modeling

    Directory of Open Access Journals (Sweden)

    B. D. Castro

    2005-09-01

    Full Text Available Liquid-liquid extraction using aqueous two-phase systems is a highly efficient technique for separation and purification of biomolecules due to the mild properties of both liquid phases. Reliable data on the phase behavior of these systems are essential for the design and operation of new separation processes; several authors reported phase diagrams for polymer-polymer systems, but data on polymer-salt systems are still relatively scarce. In this work, experimental liquid-liquid equilibrium data on water + polyethylene glycol 8000 + magnesium sulfate and water + polyethylene glycol 8000 + sodium sulfate aqueous two-phase systems were obtained at 35°C. Both equilibrium phases were analyzed by lyophilization and ashing. Experimental results were correlated with a mass-fraction-based NRTL activity coefficient model. New interaction parameters were estimated with the Simplex method. The mean deviations between the experimental and calculated compositions in both equilibrium phases is about 2%.

  7. Ionic liquid directed syntheses of water-stable Eu- and Tb-organic-frameworks for aqueous-phase detection of nitroaromatic explosives.

    Science.gov (United States)

    Qin, Jian-Hua; Ma, Bing; Liu, Xiao-Fei; Lu, Hong-Lin; Dong, Xi-Yan; Zang, Shuang-Quan; Hou, Hongwei

    2015-09-01

    Reactions of lanthanide nitrate, 1,3,5-benzenetrisbenzoic acid (H3BTB) and [RMI]Br ionic liquids (RMI = 1-alkyl-3-methylimidazolium; R = ethyl, propyl, butyl, amyl, or hexyl), gave rise to two novel lanthanide metal-organic frameworks (Ln-MOFs) [Ln(BTB)H2O], where Ln = Eu , Tb . In addition to helping solubilise the starting materials under the reaction conditions there is evidence that [RMI]Br itself can play a structure directing role and is intimately involved in template ordering in [Ln(BTB)H2O], even though neither the [RMI](+) cation nor the Br(-) anion is occluded into the ultimate structure. and are isostructural and consist of infinite rod-shaped lanthanide-carboxylate building units which are further bridged by trigonal-planar BTB ligands to give noninterpenetrated open 3D frameworks featuring a (6,6)-connected topology with the point symbol (4(4)·6(7)·8(4))(4(8)·6(7)). Importantly, the strong emission of and dispersed in water prompted us to explore their application for detection of different nitroaromatics in an aquatic system. and show similar selectivity and sensitivity towards the presence of trace amounts of nitroaromatic analytes in the aqueous phase, showing potential as explosive sensors. PMID:26174185

  8. Determination of illicit drugs in aqueous environmental samples by online solid-phase extraction coupled to liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Yao, Bo; Lian, Lushi; Pang, Weihai; Yin, Daqiang; Chan, Shen-An; Song, Weihua

    2016-10-01

    In this study, a fully automated analytical method, based on online solid phase extraction coupled to liquid chromatography-triple quadrupole tandem mass spectrometry (online SPE-LC-MS/MS), has been developed and optimized for the quantification of 10 illicit drugs and metabolites in environmentally aqueous samples collected from China. The particular attention was devoted to minimize the matrix effects through a washing step, which washed out the interferences effectively and helped to reduce the matrix effect significantly. The key advantages of the method are high sensitivity, selectivity and reliability of results, smaller sample manipulation, full automation, and fairly high throughput. The whole procedure was then successfully applied in the analysis of various surface water and wastewater effluents samples. Pseudoephedrine have been detected at trace levels (several tens ng L(-1) or less), while MDA, MDMA, benzoylecgonine and methadone were below the LOQ in all samples. Caffeine, cotinine and paraxanthine, which may be derived from medicines and foods, were detected with the highest frequencies and concentrations. PMID:27376860

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

    Science.gov (United States)

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

    2013-04-01

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

  10. Near-explicit Gas-phase Chemistry Coupled with Extensive Aqueous Mechanism: Looking at Ethanol (E85) Exhaust in a Fog

    Science.gov (United States)

    Ginnebaugh, D. L.; Jacobson, M. Z.

    2011-12-01

    We combine a near-explicit gas-phase chemical mechanism with an extensive aqueous mechanism in a chemical solver to examine the effects of ethanol (E85) versus gasoline on the fate of pollutants in the presence of a fog. We use the Master Chemical Mechanism (MCM, version 3.1, Leeds University) and the Chemical Aqueous Phase Radical Mechanism, CAPRAM 3.0, with the SMVGEAR II chemical ordinary differential solver to provide the speed necessary to simulate complex chemistry. The MCM has over 13, 500 organic reactions and 4,600 species, while CAPRAM treats aqueous chemistry among 390 species and 829 reactions (including 51 gas-to-aqueous phase reactions). We validate a simplified version of the model against results from a comprehensive intercomparison by Barth et al (2003). In previous work on ethanol (E85), we analyzed the temperature-dependence of ethanol and gasoline exhaust chemistry and its impact on urban air pollution considering only gas-phase chemistry. In addition to the air pollution findings, we verified that using the MCM with SMVGEAR is practical in a 3-D model. Here, we extend our study to include aqueous chemistry in the presence of a fog. We investigate the impact aqueous reactions have on unburned ethanol and acetaldehyde mixing ratios in the atmosphere in particular because acetaldehyde is an ozone precursor and carcinogen, and aqueous oxidation has potential to speed the conversion of unburned ethanol to acetaldehyde. Acetaldehyde also forms acetic acid in aqueous solution. Acetic acid vapor is an eye, nose, and lung irritant, so both species contribute negatively to human health. We look at the impact of fog liquid water content and temperature on the degradation of emitted aromatic and other species as well, from both gasoline and E85.

  11. Analytical predictions for vibration phase shifts along fluid-conveying pipes due to Coriolis forces and imperfections

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel; Dahl, Jonas

    2010-01-01

    Resonant vibrations of a fluid-conveying pipe are investigated, with special consideration to axial shifts in vibration phase accompanying fluid flow and various imperfections. This is relevant for understanding elastic wave propagation in general, and for the design and trouble-shooting of phase......-proportional damping, weak nonlinearity, and flow pulsation. A multiple time scaling perturbation analysis is employed for a simple model of an imperfect fluid-conveying pipe. This leads to simple analytical expressions for the approximate prediction of phase shift, providing direct insight into which imperfections...

  12. A General Analytical Method for a Three-Phase Line-Start Permanent-Magnet Synchronous Motor

    Science.gov (United States)

    Tsuboi, Kazuo; Takegami, Tsuneo; Hirotsuka, Isao; Nakamura, Masanori

    A line-start permanent-magnet synchronous motor (LSPMM) consists of a stator with symmetrical three-phase armature windings and a salient pole rotor with a permanent magnet for excitation and a starting winding similar to the squirrel-cage winding of an induction motor. In this paper, a general analytical method based on tensor analysis is proposed for practical performance calculation of a three-phase LSPMM. The general equation for the currents of the three-phase LSPMM is derived from the transient impedance tensor expressed in polyphase symmetrical axes, and the general equation for vibratory and non-vibratory torques is derived from the current equation.

  13. Stripping of TBP degraded product along with actinides from organic phase generated during the remediation of the aqueous phase of spent organic waste storage tank

    International Nuclear Information System (INIS)

    Degraded products of Tri butyl phosphate (TBP) are generated during extraction of U and Pu by PUREX due to high radiation field. Sodium carbonate wash is given to clean up the TBP solvent and the wash liquid is in a separate tank along with the spent organic waste. Though the aqueous phase from this tank comes intermediate level liquid waste category, presence of the degrade products of TBP are creating problem during its treatment by ion exchange process. To remediate this waste for ion exchange treatment, the degraded products of TBP are removed by solvent extraction using spent TBP stored in the same tank as solvent. Present paper details the stripping of the TBP degraded product along with alpha activity from the organic phase

  14. An Overview of Mode of Action and Analytical Methods for Evaluation of Gas Phase Activities of Flame Retardants

    Directory of Open Access Journals (Sweden)

    Khalifah A. Salmeia

    2015-03-01

    Full Text Available The latest techniques used to prove, describe and analyze the gas phase activity of a fire retardant used in polymeric materials are briefly reviewed. Classical techniques, such as thermogravimetric analysis or microscale combustion calorimetry, as well as complex and advanced analytical techniques, such as modified microscale combustion calorimeter (MCC, molecular beam mass spectroscopy and vacuum ultra violet (VUV photoionization spectroscopy coupled with time of flight MS (TOF-MS, are described in this review. The recent advances in analytical techniques help not only in determining the gas phase activity of the flame-retardants but also identify possible reactive species responsible for gas phase flame inhibition. The complete understanding of the decomposition pathways and the flame retardant activity of a flame retardant system is essential for the development of new eco-friendly-tailored flame retardant molecules with high flame retardant efficiency.

  15. Application of Liquid-Phase Deposition in Analytical Chemistry%液相沉积法(LPD)在分析化学中的应用

    Institute of Scientific and Technical Information of China (English)

    余琼卫; 冯钰锜

    2011-01-01

    Liquid phase deposition (LPD) technique, developed from wet chemical processing, is a new thin film-forming method to create thin oxide films from aqueous solutions. Due to the distinguishing characteristic of LPD, it has received increasing interest in recent years and been widely used in many fields, especially in the preparation of functional oxide coatings for integrated circuit, metal oxide semiconducting nanomaterials, biosensor, photocatalysis and antibacterial materials. In current review, we first briefly introduced the basic principles and characteristics of LPD and then summarized previous empirical studies for the preparation of metal oxide thin films fabricated by using LPD technique. Furthermore, the applications of LPD method in analytical chemistry, such as the preparation of separation media for chromatography and solid-phase extraction, chemical sensors and composited electrodes, are discussed in detail. At last, the future development and application of LPD in analytical chemistry is prospected.%液相沉积法(LPD)是湿化学法中发展起来的一种全新成膜方法,现已广泛应用于集成电路、金属-氧化物半导体、生物传感器、光催化及抗菌材料领域功能性薄膜的制备.本文简要介绍了液相沉积法的原理、特点及采用LPD法制备的多种金属氧化物薄膜,并详细综述了近年来液相沉积技术在分析化学领域中的应用,主要包括LPD在制备分离介质、化学传感器、复合电极等材料中的应用,并对LPD法在分析化学中的未来发展趋势进行了展望.

  16. Adsorption of Monobutyl Phthalate from Aqueous Phase onto Two Macroporous Anion-Exchange Resins

    Directory of Open Access Journals (Sweden)

    Zhengwen Xu

    2014-01-01

    Full Text Available As new emerging pollutants, phthalic acid monoesters (PAMs pose potential ecological and human health risks. In the present study, adsorption performance of monobutyl phthalate (MBP onto two macroporous base anion-exchange resins (D-201 and D-301 was discussed. It was found that the adsorption isotherms were best fitted by the Langmuir equation while the adsorption kinetics were well described by pseudo-first-order model. Analyses of sorption isotherms and thermodynamics proved that the adsorption mechanisms for DBP onto D-201 were ion exchange. However, the obtained enthalpy values indicate that the sorption process of MBP onto D-301 is physical adsorption. The equilibrium adsorption capacities and adsorption rates of DBP on two different resins increased with the increasing temperature of the solution. D-301 exhibited a higher adsorption capacity of MBP than D-201. These results proved that D-301, as an effective sorbent, can be used to remove phthalic acid monoesters from aqueous solution.

  17. Structural phase transition of merocyanine J-aggregate induced by ion-recombination in the aqueous sub-phase

    Science.gov (United States)

    Kato, Noritaka; Saito, Kentaro; Uesu, Yoshiaki

    2000-08-01

    By using the sub-phase, which contains two different kinds of counter-ions, we found a reversible thermochromic transition between different J-aggregate states of amphiphilic merocyanine dye (MD) molecules in the monolayer at the air-water interface. This chromatic change is attributed to the structural phase transition of MD J-aggregate crystallites induced by the mutual recombination of different counter-ions to MD molecules. The drastic morphological change of the MD monolayer during the transition is revealed by the in-situ observation using a multipurpose non-linear optical microscope.

  18. Aqueous-Phase Reactions of Isoprene with Sulfoxy Radical Anions as a way of Wet Aerosol Formation in the Atmosphere

    Science.gov (United States)

    Kuznietsova, I.; Rudzinski, K. J.; Szmigielski, R.; Laboratory of the Environmental Chemistry

    2011-12-01

    Atmospheric aerosols exhibit an important role in the environment. They have implications on human health and life, and - in the larger scale - on climate, the Earth's radiative balance and the cloud's formation. Organic matter makes up a significant fraction of atmospheric aerosols (~35% to ~90%) and may originate from direct emissions (primary organic aerosol, POA) or result from complex physico-chemical processes of volatile organic compounds (secondary organic aerosol, SOA). Isoprene (2-methyl-buta-1,3-diene) is one of the relevant volatile precursor of ambient SOA in the atmosphere. It is the most abundant non-methane hydrocarbon emitted to the atmosphere as a result of living vegetation. According to the recent data, the isoprene emission rate is estimated to be at the level of 500 TgC per year. While heterogeneous transformations of isoprene have been well documented, aqueous-phase reactions of this hydrocarbon with radical species that lead to the production of new class of wet SOA components such as polyols and their sulfate esters (organosulfates), are still poorly recognized. The chain reactions of isoprene with sulfoxy radical-anions (SRA) are one of the recently researched route leading to the formation of organosulfates in the aqueous phase. The letter radical species originate from the auto-oxidation of sulfur dioxide in the aqueous phase and are behind the phenomenon of atmospheric acid rain formation. This is a complicated chain reaction that is catalyzed by transition metal ions, such as manganese(II), iron(III) and propagated by sulfoxy radical anions . The presented work addresses the chemical interaction of isoprene with sulfoxy radical-anions in the water solution in the presence of nitrite ions and nitrous acid, which are important trace components of the atmosphere. We showed that nitrite ions and nitrous acid significantly altered the kinetics of the auto-oxidation of SO2 in the presence of isoprene at different solution acidity from 2 to 8

  19. Removal of diethyl phthalate from aqueous phase using magnetic poly(EGDMA-VP) beads

    Energy Technology Data Exchange (ETDEWEB)

    Tuemay Oezer, Elif [Department of Chemistry, Uludag University, Bursa (Turkey); Osman, Bilgen, E-mail: bilgeno@uludag.edu.tr [Department of Chemistry, Uludag University, Bursa (Turkey); Kara, Ali; Besirli, Necati; Guecer, Seref [Department of Chemistry, Uludag University, Bursa (Turkey); Soezeri, Hueseyin [TUBITAK-UME, National Metrology Institute, PO Box 54 TR-41470, Gebze/Kocaeli (Turkey)

    2012-08-30

    Highlights: Black-Right-Pointing-Pointer Magnetic beads were prepared for removal of diethyl phthalate (DEP). Black-Right-Pointing-Pointer Total capacity of the beads was determined as 98.9 mg DEP per gram polymer. Black-Right-Pointing-Pointer Magnetic beads were regenerated easily and reused for DEP adsorption. Black-Right-Pointing-Pointer Adsorption isotherms, kinetics and thermodynamics were elucidated. - Abstract: The barium hexaferrite (BaFe{sub 12}O{sub 19}) containing magnetic poly(ethylene glycol dimethacrylate-vinyl pyridine), (mag-poly(EGDMA-VP)) beads (average diameter = 53-212 {mu}m) were synthesized and characterized. Their use as an adsorbent in the removal of diethyl phthalate (DEP) from an aqueous solution was investigated. The mag-poly(EGDMA-VP) beads were prepared by copolymerizing of 4-vinyl pyridine (VP) with ethylene glycol dimethacrylate (EGDMA). The mag-poly(EGDMA-VP) beads were characterized by N{sub 2} adsorption/desorption isotherms (BET), vibrating sample magnetometer (VSM), X-ray powder diffraction (XRD), elemental analysis, scanning electron microscope (SEM) and swelling studies. At a fixed solid/solution ratio, the various factors affecting the adsorption of DEP from aqueous solutions such as pH, initial concentration, contact time and temperature were analyzed. The maximum DEP adsorption capacity of the mag-poly(EGDMA-VP) beads was determined as 98.9 mg/g at pH 3.0, 25 Degree-Sign C. All the isotherm data can be fitted with both the Langmuir and the Dubinin-Radushkevich isotherm models. The pseudo first-order, pseudo-second-order, Ritch-second-order and intraparticle diffusion models were used to describe the adsorption kinetics. The thermodynamic parameters obtained indicated the exothermic nature of the adsorption. The DEP adsorption capacity did not change after 10 batch successive reactions, demonstrating the usefulness of the magnetic beads in applications.

  20. Removal of diethyl phthalate from aqueous phase using magnetic poly(EGDMA–VP) beads

    International Nuclear Information System (INIS)

    Highlights: ► Magnetic beads were prepared for removal of diethyl phthalate (DEP). ► Total capacity of the beads was determined as 98.9 mg DEP per gram polymer. ► Magnetic beads were regenerated easily and reused for DEP adsorption. ► Adsorption isotherms, kinetics and thermodynamics were elucidated. - Abstract: The barium hexaferrite (BaFe12O19) containing magnetic poly(ethylene glycol dimethacrylate–vinyl pyridine), (mag-poly(EGDMA–VP)) beads (average diameter = 53–212 μm) were synthesized and characterized. Their use as an adsorbent in the removal of diethyl phthalate (DEP) from an aqueous solution was investigated. The mag-poly(EGDMA–VP) beads were prepared by copolymerizing of 4-vinyl pyridine (VP) with ethylene glycol dimethacrylate (EGDMA). The mag-poly(EGDMA–VP) beads were characterized by N2 adsorption/desorption isotherms (BET), vibrating sample magnetometer (VSM), X-ray powder diffraction (XRD), elemental analysis, scanning electron microscope (SEM) and swelling studies. At a fixed solid/solution ratio, the various factors affecting the adsorption of DEP from aqueous solutions such as pH, initial concentration, contact time and temperature were analyzed. The maximum DEP adsorption capacity of the mag-poly(EGDMA–VP) beads was determined as 98.9 mg/g at pH 3.0, 25 °C. All the isotherm data can be fitted with both the Langmuir and the Dubinin-Radushkevich isotherm models. The pseudo first-order, pseudo-second-order, Ritch-second-order and intraparticle diffusion models were used to describe the adsorption kinetics. The thermodynamic parameters obtained indicated the exothermic nature of the adsorption. The DEP adsorption capacity did not change after 10 batch successive reactions, demonstrating the usefulness of the magnetic beads in applications.

  1. Aqueous organic phases separation by membrane reactors in bio desulfurization reactions

    International Nuclear Information System (INIS)

    This work presents o membrane bioreactor prototype used to separate emulsion phases formed in the bio desulfurization reaction. Hydrophobic membranes used for the construction of the prototype allow the separation of the organic/watery phases. The separation unit resembles o tube and carcass heat exchanger. by feeding the emulsion through the housing and due to the pressure gradient pushed on the membrane, the organic phase pass through and allow to obtain on organic phase free of cells and water. Several organic phase/watery phase ratios and many cellular concentrations were evaluated. Results indicate that is possible to separate the phases by manipulating the fluid pressure within the bioreactor. This is possible even for cellular concentrations of the order of 7 g/l. the system can also be used as a reaction unit. The biological conversion was evaluated by verifying the presence of 2-HBP one of the metabolites of the path 45 in the bio desulfurization reaction. This bioreactor configuration has not been explored before for the bio desulfurization process and therefore it represents an innovation in this research area

  2. Extraction of penicillin G by aqueous two-phase system of [Bmim]BF4/NaH2PO4

    Institute of Scientific and Technical Information of China (English)

    LIU Qingfen; HU Xuesheng; WANG Yuhong; YANG Ping; XIA Hansong; YU Jiang; LIU Huizhou

    2005-01-01

    A novel approach for the extraction of penicillin G by aqueous two-phase system comprised of hydrophilic ionic liquid [Bmim]BF4 (1-butyl-3- methylimidazolium tetrafluoroborate) and NaH2PO4 is reported. The effects of some important parameters involving the concentration of NaH2PO4, the concentration of penicillin G, the amount of [Bmim]BF4 on the formation of aqueous two-phase system and the extraction yield of penicillin were investigated. The primary result shows that the ATPS can take advantage of penicillin concentrated in upper phase at higher pH value for penicillin extraction from its aqueous solution without emulsification.

  3. High-Yield Synthesis of Silver Nanoparticles by Precipitation in a High-Aqueous Phase Content Reverse Microemulsion

    Directory of Open Access Journals (Sweden)

    Y. D. Sosa

    2010-01-01

    Full Text Available Silver nanoparticles were precipitated at 70°C in a reverse microemulsion containing a high concentration of 0.5 M silver nitrate aqueous solution, toluene as organic phase, and a mixture of surfactants sodium bis (2-ethylhexyl sulfosuccinate/sodium dodecyl sulfate (2/1, w/w. Nanoparticles were characterized by X-ray diffraction, atomic absorption spectroscopy, and high-resolution transmission electron microscopy. In spite of the high-water/surfactant molar ratio and concentration of silver nitrate solution used in this study, characterizations demonstrated that nanoparticles were silver crystals (purity >99% with 8.6–8.8 nm in average diameter and 2.9–4.7 nm in standard deviation. It is proposed that slow dosing rate of aqueous solution of precipitating agent and the small molecular volume of toluene attenuated both particle aggregation and polydispersity widening. Experimental yield of silver nanoparticles obtained in this study was much higher than theoretical yields calculated from available data in the literature on preparation of silver nanoparticles in reverse microemulsions.

  4. Photocatalytic degradation of different chromophoric dyes in aqueous phase using La and Mo doped TiO2 hybrid carbon spheres

    International Nuclear Information System (INIS)

    Highlights: • La and Mo doped TiO2 hybrid carbon spheres have been synthesized using hydrothermal method. • The characterization of La and Mo doped TiO2 hybrid carbon spheres uniform morphology having anatase phase and good structural stability. • TiO2 hybrid carbon spheres with dopant concentration of 2.0% (La) and 1.5% (Mo) showed the highest photocatalytic activity as compared to the other dopant concentrations for the degradation of all the dyes under investigation. - Abstract: La and Mo-doped TiO2 coated carbon spheres have been synthesized using the hydrothermal method. The prepared materials were characterized by standard analytical techniques, X-ray diffraction (XRD), UV–Vis spectrophotometry, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and Raman spectroscopy. The XRD and Raman spectroscopic analysis showed that the particles are in anatase phase. The EDX and SEM images showed that La/Mo-doped TiO2 are present on the surface of the carbon spheres. The photocatalytic activity of the synthesized particles were tested by studying the degradation of three different chromophoric dyes, i.e., Acid Yellow 29 (azo dye), Coomassie Brilliant Blue G250 (triphenylmethane dye) and Acid Green 25 (anthraquinone dye) as a function of time on irradiation in aqueous suspension. TiO2 particle with dopant concentration of 2.0% La and 1.5% Mo showed the highest photocatalytic activity as compared to the other dopant concentrations for the degradation of all the dyes under investigation

  5. Photocatalytic degradation of different chromophoric dyes in aqueous phase using La and Mo doped TiO{sub 2} hybrid carbon spheres

    Energy Technology Data Exchange (ETDEWEB)

    Raza, Waseem; Haque, M.M. [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India); Muneer, M., E-mail: m.muneer.ch@amu.ac.in [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India); Fleisch, M.; Hakki, A.; Bahnemann, D. [Institut fuer Technische Chemie, Leibniz Universität Hannover, Callinstrasse 3, D-30167 Hannover (Germany)

    2015-05-25

    Highlights: • La and Mo doped TiO{sub 2} hybrid carbon spheres have been synthesized using hydrothermal method. • The characterization of La and Mo doped TiO{sub 2} hybrid carbon spheres uniform morphology having anatase phase and good structural stability. • TiO{sub 2} hybrid carbon spheres with dopant concentration of 2.0% (La) and 1.5% (Mo) showed the highest photocatalytic activity as compared to the other dopant concentrations for the degradation of all the dyes under investigation. - Abstract: La and Mo-doped TiO{sub 2} coated carbon spheres have been synthesized using the hydrothermal method. The prepared materials were characterized by standard analytical techniques, X-ray diffraction (XRD), UV–Vis spectrophotometry, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and Raman spectroscopy. The XRD and Raman spectroscopic analysis showed that the particles are in anatase phase. The EDX and SEM images showed that La/Mo-doped TiO{sub 2} are present on the surface of the carbon spheres. The photocatalytic activity of the synthesized particles were tested by studying the degradation of three different chromophoric dyes, i.e., Acid Yellow 29 (azo dye), Coomassie Brilliant Blue G250 (triphenylmethane dye) and Acid Green 25 (anthraquinone dye) as a function of time on irradiation in aqueous suspension. TiO{sub 2} particle with dopant concentration of 2.0% La and 1.5% Mo showed the highest photocatalytic activity as compared to the other dopant concentrations for the degradation of all the dyes under investigation.

  6. Cell separation in immunoaffinity partition in aqueous polymer two-phase systems

    Science.gov (United States)

    Karr, Laurel J.; Van Alstine, James M.; Snyder, Robert S.; Shafer, Steven G.; Harris, J. Milton

    1989-01-01

    Two methods for immunoaffinity partitioning are described. One technique involves the covalent coupling of poly (ethylene glycol) (PEG) to immunoglobulin G antibody preparations. In the second method PEG-modified Protein A is used to complex with cells and unmodified antibody. The effects of PEG molecular weight, the degree of modification, and varying phase system composition on antibody activity and its affinity for the upper phase are studied. It is observed that both methods resulted in effective cell separation.

  7. Phase equilibrium conditions for simulated landfill gas hydrate formation in aqueous solutions of tetrabutylammonium nitrate

    International Nuclear Information System (INIS)

    Highlights: • Hydrate equilibrium conditions for the simulated landfill gas (LFG) were reported. • Thermodynamic effect of tetrabutylammonium nitrate changes with its mass fraction. • The phase boundary was determined by employing an isochoric pressure-search method. -- Abstract: Hydrate phase equilibrium conditions for the simulated landfill gas (LFG) of methane and carbon dioxide (50 mol% methane, 50 mol% carbon dioxide) were investigated with the pressure range of (1.90 to 13.83) MPa and temperature range of (280.0 to 288.3) K at (0.050, 0.170, 0.340, and 0.394) mass fraction (w) of tetrabutylammonium nitrate (TBANO3). The phase boundary between liquid–vapor–hydrate (L–V–H) phases and liquid–vapor (L–V) phases was determined by employing an isochoric pressure-search method. The phase equilibrium data measured showed that TBANO3 appeared a remarkable promotion effect at wTBANO3 = 0.394, corresponding to TBANO3 · 26H2O, but inhibition effect at wTBANO3 = (0.050, or 0.170) on the semiclathrate hydrate formation. In addition, the application of TBANO3 at 0.340 mass fraction, corresponding to TBANO3 · 32H2O, displayed promotion effect at lower pressures (below 6.38 MPa) and inhibition effect at higher pressures (above 6.38 MPa)

  8. Molecular transformations of phenolic SOA during photochemical aging in the aqueous phase: competition among oligomerization, functionalization, and fragmentation

    Directory of Open Access Journals (Sweden)

    L. Yu

    2015-10-01

    Full Text Available Organic aerosol is formed and transformed in atmospheric aqueous phases (e.g., cloud and fog droplets and deliquesced airborne particles containing small amounts of water through a multitude of chemical reactions. Understanding these reactions is important for a predictive understanding of atmospheric aging of aerosols and their impacts on climate, air quality, and human health. In this study, we investigate the chemical evolution of aqueous secondary organic aerosol (aqSOA formed during reactions of phenolic compounds with two oxidants – the triplet excited state of an aromatic carbonyl (3C* and hydroxyl radical (•OH. Changes in the molecular composition of aqSOA as a function of aging time are characterized using an offline nanospray desorption electrospray ionization mass spectrometer (nano-DESI MS whereas the real-time evolution of SOA mass, elemental ratios, and average carbon oxidation state (OSC are monitored using an online aerosol mass spectrometer (AMS. Our results indicate that oligomerization is an important aqueous reaction pathway for phenols, especially during the initial stage of photooxidation equivalent to ∼ 2 h irradiation under midday, winter solstice sunlight in northern California. At later reaction times functionalization (i.e., adding polar oxygenated functional groups to the molecule and fragmentation (i.e., breaking of covalent bonds become more important processes, forming a large variety of functionalized aromatic and open-ring products with higher OSC values. Fragmentation reactions eventually dominate the photochemical evolution of phenolic aqSOA, forming a large number of highly oxygenated open-ring molecules with carbon numbers (nC below 6. The average nC of phenolic aqSOA decreases while average OSC increases over the course of photochemical aging. In addition, the saturation vapor pressures C* of dozens of the most abundant phenolic aqSOA molecules are estimated. A wide range of C* values is

  9. Molecular transformations of phenolic SOA during photochemical aging in the aqueous phase: competition among oligomerization, functionalization, and fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Lu; Smith, Jeremy; Laskin, Alexander; George, Kathryn; Anastasio, Cort N.; Laskin, Julia; Dillner, Ann M.; Zhang, Qi

    2016-04-13

    Organic aerosol is formed and transformed in atmospheric aqueous phases (e.g., cloud and fog droplets and aerosol particles containing small amounts of water) through a multitude of chemical reactions. Understanding these reactions is important for a predictive understanding of atmospheric aging of aerosol particles and their impacts on climate, air quality, and human health. In this study, we investigate the chemical evolution of aqueous secondary organic aerosol (aqSOA) formed during reactions of phenolic compounds with two oxidants – the triplet excited state of an aromatic carbonyl (3C*) and hydroxyl radical (•OH). Changes in the molecular composition of aqSOA as a function of aging time are characterized using an offline nanospray desorption electrospray ionization mass spectrometer (nano-DESI MS) whereas the real-time evolution of SOA mass, elemental ratios, and average carbon oxidation state (OSC) are monitored using an online aerosol mass spectrometer (AMS). Our results indicate that oligomerization is an important aqueous reaction pathway for phenols, especially during the initial stage of photooxidation equivalent to ~ 2 hours irradiation under midday, winter solstice sunlight in northern California. At later reaction times functionalization (i.e., adding polar oxygenated functional groups to the molecule) and fragmentation (i.e., breaking of covalent bonds) become more important processes, forming a large variety of functionalized aromatic and open-ring products with higher OSC values. Fragmentation reactions eventually dominate the photochemical evolution of phenolic aqSOA, forming a large number of highly oxygenated open-ring molecules with carbon numbers (nC) below 6. The average nC of phenolic aqSOA decreases while average OSC increases over the course of photochemical aging. In addition, the saturation vapor pressures (C*) of dozens of the most abundant phenolic aqSOA molecules are estimated. A wide range of C* values is observed, varying from

  10. Molecular transformations of phenolic SOA during photochemical aging in the aqueous phase: competition among oligomerization, functionalization, and fragmentation

    Science.gov (United States)

    Yu, Lu; Smith, Jeremy; Laskin, Alexander; George, Katheryn M.; Anastasio, Cort; Laskin, Julia; Dillner, Ann M.; Zhang, Qi

    2016-04-01

    Organic aerosol is formed and transformed in atmospheric aqueous phases (e.g., cloud and fog droplets and deliquesced airborne particles containing small amounts of water) through a multitude of chemical reactions. Understanding these reactions is important for a predictive understanding of atmospheric aging of aerosols and their impacts on climate, air quality, and human health. In this study, we investigate the chemical evolution of aqueous secondary organic aerosol (aqSOA) formed during reactions of phenolic compounds with two oxidants - the triplet excited state of an aromatic carbonyl (3C∗) and hydroxyl radical (•OH). Changes in the molecular composition of aqSOA as a function of aging time are characterized using an offline nanospray desorption electrospray ionization mass spectrometer (nano-DESI MS) whereas the real-time evolution of SOA mass, elemental ratios, and average carbon oxidation state (OSC) are monitored using an online aerosol mass spectrometer (AMS). Our results indicate that oligomerization is an important aqueous reaction pathway for phenols, especially during the initial stage of photooxidation equivalent to ˜ 2 h irradiation under midday winter solstice sunlight in Northern California. At later reaction times functionalization (i.e., adding polar oxygenated functional groups to the molecule) and fragmentation (i.e., breaking of covalent bonds) become more important processes, forming a large variety of functionalized aromatic and open-ring products with higher OSC values. Fragmentation reactions eventually dominate the photochemical evolution of phenolic aqSOA, forming a large number of highly oxygenated ring-opening molecules with carbon numbers (nC) below 6. The average nC of phenolic aqSOA decreases while average OSC increases over the course of photochemical aging. In addition, the saturation vapor pressures (C∗) of dozens of the most abundant phenolic aqSOA molecules are estimated. A wide range of C∗ values is observed, varying

  11. Solid-phase development of a L-hydroxybenzotriazole linker for heterocycle synthesis using analytical constructs.

    Science.gov (United States)

    Scicinski, J J; Congreve, M S; Jamieson, C; Ley, S V; Newman, E S; Vinader, V M; Carr, R A

    2001-01-01

    The development of a 1-hydroxybenzotriazole linker for the synthesis of heterocyclic derivatives is described, utilizing analytical construct methodology to facilitate the analysis of resin samples. A UV-chromophore-containing analytical construct enabled the accurate determination of resin loading and the automated monitoring of key reactions using only small quantities of resin. The syntheses of an array of isoxazole derivatives are reported. PMID:11442396

  12. Investigation on the extraction of strontium ions from aqueous phase using crown ether-ionic liquid systems

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The extraction of strontium ions using DCH18C6 as the extractant and various ionic liquids(ILs) as solvents has been investigated.The distribution ratio of Sr2+ can reach as high as 103 under certain conditions,much larger than that in DCH18C6/n-octanol system.The extraction capacity depends greatly on the structure of ionic liquids.In Ils-based extraction systems,the extraction efficiency of strontium ions is reduced by increasing the concentration of nitric acid and can also be influenced directly by the presence of Na+ and K+ in the aqueous phase.It is confirmed that the extraction proceeds mainly via a cation-exchange mechanism.

  13. Quantification of the antifungal lipopeptide iturin A by high performance liquid chromatography coupled with aqueous two-phase extraction.

    Science.gov (United States)

    Yuan, Jun; Raza, Waseem; Huang, Qiwei; Shen, Qirong

    2011-09-15

    Iturin A, a powerful antifungal surfactant, is a kind of bacterial lipopeptide produced by Bacillus strains. This study addresses the use of an aqueous two-phase system (ATPS) using ethanol/ammonium sulfate to extract iturin A from Bacillus amyloliquefaciens NJN-6 fermentation broth and the quantification of iturin A by HPLC. Baseline separation of iturin A homologues was performed using an RP-C(18) column with a mixture of water and acetonitrile. The results showed that the correlation coefficient between integral area and concentration was 0.9961 within the range of 20-140 mg/l. The RSD of the retention time and the peak area were 1.29% and 1.45%, respectively. The effects of some operating parameters in ATPS, e.g., pH, temperature and centrifugation time, were also studied. This method can be successfully used for the rapid quantification of iturin A. PMID:21872538

  14. Optimization of aqueous enzymatic oil extraction from kernel of oil palm (elaeis guineensis) using three phase partitioning and microwave

    International Nuclear Information System (INIS)

    The use of microwave irradiation as a pretreatment before aqueous enzymatic oil extraction from oil palm kernel was found to be useful. The microwave irradiation for 10 min -assisted extraction was found to be a simpler and more effective alternative to the solvent extraction methods for the productions of palm kernel oil. Further enhancement was achieved when the microwave irradiated slurries were treated with a commercial enzyme preparation of proteases, followed by three phase partitioning. This resulted in 93% (w/w) oil yields form the palm kernel. The efficiency of the present technique is comparable to solvent extraction with an added advantage of being less time consuming and using t-butanol which is a safer solvent as compared to n-hexane used in conventional oil extraction process. The technique also tries to reduce the amount of enzyme used and hence reduces the overall cost. (author)

  15. Noble metal catalyzed aqueous phase hydrogenation and hydrodeoxygenation of lignin-derived pyrolysis oil and related model compounds.

    Science.gov (United States)

    Mu, Wei; Ben, Haoxi; Du, Xiaotang; Zhang, Xiaodan; Hu, Fan; Liu, Wei; Ragauskas, Arthur J; Deng, Yulin

    2014-12-01

    Aqueous phase hydrodeoxygenation of lignin pyrolysis oil and related model compounds were investigated using four noble metals supported on activated carbon. The hydrodeoxygenation of guaiacol has three major reaction pathways and the demethylation reaction, mainly catalyzed by Pd, Pt and Rh, produces catechol as the products. The presence of catechol and guaiacol in the reaction is responsible for the coke formation and the catalysts deactivation. As expected, there was a significant decrease in the specific surface area of Pd, Pt and Rh catalysts during the catalytic reaction because of the coke deposition. In contrast, no catechol was produced from guaiacol when Ru was used so a completely hydrogenation was accomplished. The lignin pyrolysis oil upgrading with Pt and Ru catalysts further validated the reaction mechanism deduced from model compounds. Fully hydrogenated bio-oil was produced with Ru catalyst. PMID:25280108

  16. Transformation of Vesicles in Aqueous Two-Phase System of an Anionic Gemini Surfactant and a Cationic Conventional Surfactant Mixture

    Institute of Scientific and Technical Information of China (English)

    JIANG Rong; HUANG Yi-Xiong; ZHAO Jian-Xi; HUANG Chang-Cang

    2008-01-01

    Transformation of vesicles formed in DTAB/C11-p-PhCNa aqueous surfactant two-phase (ASTP) was observed by the transmission electron microscopy (TEM). The trans-conformation of the gemini surfactant in the aggregates was considered to be the important factor for constructing the multi-lamellar structure of the vesicle wall. The cation-π interaction between the quaternary ammonium cation and the aromatic ring in the spacer was determined by the UV-Vis spectrum analysis, which, as well as the general electrostatic attraction and hydrophobic force, contributes to the stability of the multi-lamellar structure. The concentrations of the surface-active ions were measured for understanding the mechanism of vesicle transformation. The results show that isoelectric mixing of the two components benefits the growth of vesicles both in size and wall thickness.

  17. Base-Free Aqueous-Phase Oxidation of 5-Hydroxymethylfurfural over Ruthenium Catalysts Supported on Covalent Triazine Frameworks.

    Science.gov (United States)

    Artz, Jens; Palkovits, Regina

    2015-11-01

    The base-free aqueous-phase oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxilic acid (FDCA) was performed at 140 °C and 20 bar of synthetic air as the oxidant. Ru clusters supported on covalent triazine frameworks (CTFs) enabled superior conversion (99.9%) and FDCA yields in comparison to other support materials such as activated carbon and γ-Al2O3 after only 1 h. The properties of the CTFs such as pore volume, specific surface area, and polarity could be tuned by using different monomers. These material properties influence the catalytic activity of Ru/CTF significantly as mesoporous CTFs showed superior activity compared to microporous materials, whereas high polarities provide further beneficial effects. The recyclability of the prepared Ru/CTF catalysts was comparable to that of Ru/C at high conversions and product yields. Nevertheless, minor deactivation in five successive recycling experiments was observed. PMID:26482331

  18. Fourier Transform Infrared Spectroscopy for Identification and Quantification of Organic Functional Groups in Aqueous Phase Secondary Organic Aerosol

    Science.gov (United States)

    George, K.; Ruthenburg, T. C.; Smith, J.; Anastasio, C.; Dillner, A. M.

    2011-12-01

    Particles in the atmosphere influence visibility, climate, and human health. Secondary organic aerosols (SOA) formed from chemical reactions in the atmosphere constitute a portion of total organic particle mass. Most research on SOA has focused on gas phase reactions; however, reactions taking place in cloud and fog drops may be significant. One group of water-soluble compounds that participate in these reactions is phenols. Phenols, emitted from biomass burning, react in the aqueous phase to form low-volatility SOA products. The products formed from these reactions are currently poorly characterized. In order to characterize laboratory-generated samples, we are developing an attenuated total reflectance-Fourier transform infrared spectroscopic (ATR-FTIR) technique to identify and quantify organic functional groups in SOA. Aqueous SOA is made in the laboratory by illuminating solutions of phenolic compounds with an oxidant. The illuminated solution is then blown to dryness in order to determine the mass of SOA produced. The dry SOA is reconstituted in water and drops of this solution are placed onto a single-reflection ATR accessory. In order to identify and quantify functional groups in the complex SOA samples, it is necessary to calibrate with compounds and mixtures of compounds containing bond types similar to those found in the laboratory-generated SOA. Initially, focus has been placed on multiple peaks located in the region between 1800 cm-1 and 800 cm-1, including peaks for C=O and C-O. We distinguish between characteristic absorbances to begin determining the organic functional group composition of the SOA samples. This ATR-FTIR technique complements information from mass spectrometry measurements and allows us to quantify organic mass for non-volatile SOA products.

  19. Aqueous Phase Glycerol Reforming by PtMo Bimetallic Nano-Particle Catalyst: Product Selectivity and Structural Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Stach E. A.; Dietrich, P.J.; Lobo-Lapidus, R.J.; Wu, T.; Sumer, A.; Akatay, M.C.; Fingland, B.R.; Guo, N.; Dumesic, J.A.; Marshall, C.L.; Jellinek, J.; Delgass, W.N.; Ribeiro, F.H.; Miller, J.T.

    2012-03-01

    A carbon supported PtMo aqueous phase reforming catalyst for producing hydrogen from glycerol was characterized by analysis of the reaction products and pathway, TEM, XPS and XAS spectroscopy. Operando X-ray absorption spectroscopy (XAS) indicates the catalyst consists of bimetallic nano-particles with a Pt rich core and a Mo rich surface. XAS of adsorbed CO indicates that approximately 25% of the surface atoms are Pt. X-ray photoelectron spectroscopy indicates that there is unreduced and partially reduced Mo oxide (MoO{sub 3} and MoO{sub 2}), and Pt-rich PtMo bimetallic nano-particles. The average size measured by transmission electron microscopy of the fresh PtMo nano-particles is about 2 nm, which increases in size to 5 nm after 30 days of glycerol reforming at 31 bar and 503 K. The catalyst structure differs from the most energetically stable structure predicted by density functional theory (DFT) calculations for metallic Pt and Mo atoms. However, DFT indicates that for nano-particles composed of metallic Pt and Mo oxide, the Mo oxide is at the particle surface. Subsequent reduction would lead to the experimentally observed structure. The aqueous phase reforming reaction products and intermediates are consistent with both C-C and C-OH bond cleavage to generate H{sub 2}/CO{sub 2} or the side product CH{sub 4}. While the H{sub 2} selectivity at low conversion is about 75%, cleavage of C-OH bonds leads to liquid products with saturated carbon atoms. At high conversions (to gas), these will produced additional CH{sub 4} reducing the H{sub 2} yield and selectivity.

  20. The diastereomers of mannosylerythritol lipids have different interfacial properties and aqueous phase behavior, reflecting the erythritol configuration.

    Science.gov (United States)

    Fukuoka, Tokuma; Yanagihara, Takashi; Imura, Tomohiro; Morita, Tomotake; Sakai, Hideki; Abe, Masahiko; Kitamoto, Dai

    2012-04-01

    Mannosylerythritol lipids (MELs) produced by yeasts are one of the most promising glycolipid biosurfactants. There are two MEL diastereomers, in which the configurations of the erythritol moieties are opposite. The 4-O-β-D-mannopyranosyl-(2S,3R)-erythritol (S-form) or 4-O-β-D-mannopyranosyl-(2R,3S)-erythritol (R-form) is the hydrophilic domain. In this study, we prepared S- and R-form MEL homologs with similar fatty acyl groups, and compared their interfacial properties. Among the four diastereomers (S-MEL-B and -D/R-MEL-B and -D), R-form MELs showed a higher critical aggregation concentration and hydrophilicity compared to the corresponding S-form. R-form MELs also efficiently formed relatively large vesicles compared to S-form. Moreover, we estimated the binary phase diagram of the MEL-water system and compared the aqueous phase behavior among the four diastereomers. The present MELs self-assembled into a lamellar (L(α)) structure at all concentration ranges. Meanwhile, the one-phase L(α) region of R-form MELs was wider than those of S-form MELs. R-form MELs may maintain more water between the polar layers in accordance with an extension of the interlayer spacing. These results suggest that the differences in MEL carbohydrate configurations significantly affect interfacial properties, self-assembly, and hydrate ability. PMID:22341919

  1. Thermal conductivity and phase-change properties of aqueous alumina nanofluid

    International Nuclear Information System (INIS)

    Highlights: ► The alumina nanofluid with chitosan was produced by two-step synthesis method. ► The k and phase-change properties of alumina nanofluid were examined. ► Adding Al2O3 nanoparticles into water indeed improves the k. ► Adding the chitosan decreases the thermal conductivity of alumina nanofluid. ► The Tcp and hc are 53.4% and 97.8% of those in DW with the optimal combination. - Abstract: This study uses thermal conductivity and differential scanning calorimeter experiments to explore the thermal conductivity and phase-change properties of alumina (Al2O3)–water nanofluid produced using a two-step synthesis method. Deionized water (DW) is used as a control group, and the Al2O3–water nanofluid uses chitosan as a dispersant. Nanoparticle morphology and materials were confirmed using transmission electron microscopy (TEM) and X-ray diffraction (XRD), respectively. The results show that adding Al2O3 nanoparticles to DW improves DW thermal conductivity, but adding chitosan reduces the thermal conductivity of Al2O3–water nanofluid. Adding the nanoparticles to DW affects the phase-change peak temperature and phase change heat. The optimal combination is 0.1 wt.% chitosan and 0.5 wt.% Al2O3 nanoparticles; the charging phase-change peak temperature and latent heat are 53.4% and 97.8% of those in DW, respectively

  2. Supercritical Fluid Extraction Directly Coupled with Reversed Phase Liquid Chromatography for Quantitative Analysis of Analytes in Complex Matrices

    OpenAIRE

    Wang, Zhenyu

    2004-01-01

    The purpose of this research was to design a simple, novel interface for on-line coupling of Supercritical Fluid Extraction (SFE) with High Performance Reversed Phase Liquid Chromatography (HP-RPLC), and to explore its ability for quantitative analysis of analytes in different matrices. First, a simple interface was developed via a single one six-port injection valve to connect the SFE and LC systems. A water displacement method was utilized to eliminate decompressed CO2 gas in the solid phas...

  3. An Overview of Mode of Action and Analytical Methods for Evaluation of Gas Phase Activities of Flame Retardants

    OpenAIRE

    Khalifah A. Salmeia; Julien Fage; Shuyu Liang; Sabyasachi Gaan

    2015-01-01

    The latest techniques used to prove, describe and analyze the gas phase activity of a fire retardant used in polymeric materials are briefly reviewed. Classical techniques, such as thermogravimetric analysis or microscale combustion calorimetry, as well as complex and advanced analytical techniques, such as modified microscale combustion calorimeter (MCC), molecular beam mass spectroscopy and vacuum ultra violet (VUV) photoionization spectroscopy coupled with time of flight MS (TOF-MS), are d...

  4. Phase effects on chemical behaviors of tin, antimony and tellurium fission products in aqueous solutions

    International Nuclear Information System (INIS)

    The oxidation states of tin, antimony and tellurium isotopes formed predominantly (>91%) by fission were investigated in aqueous solutions of 233U irradiated in a reactor. Results were corrected for the thermal reactions with the bulk radiolysis products using tracers for each element. In 0.4 M H2SO4 solutions containing 4.3 mM 233UO22+, 1.5 mM Te(IV) and 1.5 mM Te(VI), the fraction of Te(IV) is 98 +- 2% in the absence of oxygen and 92 +- 3% in the presence of oxygen. In frozen solutions of the same composition, the fraction of Te(IV) is 83 +- 2% in the absence of oxygen and 81 +- 3% in the presence of oxygen. Similar differences are also found in the case of the antimony isotopes in 0.4 M H2SO4 solutions and the tin isotopes in 1 M HCl solutions. For the interpretation of the differences, the reducing action of the species diffusing from the track of the fission fragments is considered. (author)

  5. Aqueous Phase Synthesis of ZIF-8 Membrane with Controllable Location on an Asymmetrically Porous Polymer Substrate.

    Science.gov (United States)

    Shamsaei, Ezzatollah; Lin, Xiaocheng; Low, Ze-Xian; Abbasi, Zahra; Hu, Yaoxin; Liu, Jefferson Zhe; Wang, Huanting

    2016-03-01

    In this study, we have demonstrated a simple, scalable, and environmentally friendly route for controllable fabrication of continuous, well-intergrown ZIF-8 on a flexible polymer substrate via contra-diffusion method in conjunction with chemical vapor modification of the polymer surface. The combined chemical vapor modification and contra-diffusion method resulted in controlled formation of a thin, defect-free, and robust ZIF-8 layer on one side of the support in aqueous solution at room temperature. The ZIF-8 membrane exhibited propylene permeance of 1.50 × 10(-8) mol m(-2) s(-1) Pa(-1) and excellent selective permeation properties; after post heat-treatment, the membrane showed ideal selectivities of C3H6/C3H8 and H2/C3H8 as high as 27.8 and 2259, respectively. The new synthesis approach holds promise for further development of the fabrication of high-quality polymer-supported ZIF membranes for practical separation applications. PMID:26886288

  6. Aqueous Phase Synthesis and Enhanced Field Emission Properties of ZnO-Sulfide Heterojunction Nanowires.

    Science.gov (United States)

    Wang, Guojing; Li, Zhengcao; Li, Mingyang; Chen, Chienhua; Lv, Shasha; Liao, Jiecui

    2016-01-01

    ZnO-CdS, ZnO-ZnS, and ZnO-Ag2S core-shell heterojunction structures were fabricated using low-temperature, facile and simple aqueous solution approaches. The polycrystalline sulfide shells effectively enhance the field emission (FE) properties of ZnO nanowires arrays (NWAs). This results from the formation of the staggered gap heterointerface (ZnO-sulfide) which could lead to an energy well at the interfaces. Hence, electrons can be collected when an electric field is applied. It is observed that ZnO-ZnS NWAs have the lowest turn-on field (3.0 Vμm(-1)), compared with ZnO-CdS NWAs (6.3 Vμm(-1)) and ZnO-Ag2S NWAs (5.0 Vμm(-1)). This may be associated with the pyramid-like ZnS shell which increases the number of emission nanotips. Moreover, the Fowler-Nordheim (F-N) plot displays a nonlinear relationship in the low and high electric field regions caused by the double well potential effect of the heterojunction structures. PMID:27387653

  7. Irradiation of ultrasound to 5-methylbenzotriazole in aqueous phase: Degradation kinetics and mechanisms.

    Science.gov (United States)

    Kim, Duk K; He, Yingxin; Jeon, Junho; O'Shea, Kevin E

    2016-07-01

    Ultrasonic irradiation (640kHz) leads to the effective degradation of 5-methyl-benzotriazole (5-MBT) in O2 saturated aqueous solution. Up to 97% of 5-MBT is eliminated within 2h of treatment. Upon extended treatment of 6h, UV absorbance of the n→π(∗) and π→π(∗) transitions associated with aromatic and conjugated systems are completely removed, indicating complete destruction of the aromatic system in 5-MBT. The decomposition of 5-MBT follows pseudo-first order kinetics and the observed decomposition rate dropped significantly in the presence of tertiary butyl alcohol. Detailed product studies were performed employing a negative mode ESI LC-MS. Twenty eight intermediate products were detected during ultrasonic mediated degradation of 5-MBT. Reaction pathways are proposed based on the structures of products assigned to observed 28 masses from LC-MS and commonly accepted degradation pathways observed by thermal and hydroxyl radical mediated pathways often associated with ultrasonic treatment. PMID:26964945

  8. Analytic signal phase-based myocardial motion estimation in tagged MRI sequences by a bilinear model and motion compensation.

    Science.gov (United States)

    Wang, Liang; Basarab, Adrian; Girard, Patrick R; Croisille, Pierre; Clarysse, Patrick; Delachartre, Philippe

    2015-08-01

    Different mathematical tools, such as multidimensional analytic signals, allow for the calculation of 2D spatial phases of real-value images. The motion estimation method proposed in this paper is based on two spatial phases of the 2D analytic signal applied to cardiac sequences. By combining the information of these phases issued from analytic signals of two successive frames, we propose an analytical estimator for 2D local displacements. To improve the accuracy of the motion estimation, a local bilinear deformation model is used within an iterative estimation scheme. The main advantages of our method are: (1) The phase-based method allows the displacement to be estimated with subpixel accuracy and is robust to image intensity variation in time; (2) Preliminary filtering is not required due to the bilinear model. The proposed algorithm, integrating phase-based optical flow motion estimation and the combination of global motion compensation with local bilinear transform, allows spatio-temporal cardiac motion analysis, e.g. strain and dense trajectory estimation over the cardiac cycle. Results from 7 realistic simulated tagged magnetic resonance imaging (MRI) sequences show that our method is more accurate compared with state-of-the-art method for cardiac motion analysis and with another differential approach from the literature. The motion estimation errors (end point error) of the proposed method are reduced by about 33% compared with that of the two methods. In our work, the frame-to-frame displacements are further accumulated in time, to allow for the calculation of myocardial Lagrangian cardiac strains and point trajectories. Indeed, from the estimated trajectories in time on 11 in vivo data sets (9 patients and 2 healthy volunteers), the shape of myocardial point trajectories belonging to pathological regions are clearly reduced in magnitude compared with the ones from normal regions. Myocardial point trajectories, estimated from our phase-based analytic

  9. Comparison of analytical protein separation characteristics for three amine-based capillary-channeled polymer (C-CP) stationary phases.

    Science.gov (United States)

    Jiang, Liuwei; Marcus, R Kenneth

    2016-02-01

    Capillary-channeled polymer (C-CP) fiber stationary phases are finding utility in the realms of protein analytics as well as downstream processing. We have recently described the modification of poly(ethylene terephthalate) (PET) C-CP fibers to affect amine-rich phases for the weak anion-exchange (WAX) separation of proteins. Polyethylenimine (PEI) is covalently coupled to the PET surface, with subsequent cross-linking imparted by treatment with 1,4-butanediol diglycidyl ether (BUDGE). These modifications yield vastly improved dynamic binding capacities over the unmodified fibers. We have also previously employed native (unmodified) nylon 6 C-CP fibers as weak anion/cation-exchange (mixed-mode) and hydrophobic interaction chromatography (HIC) phases for protein separations. Polyamide, nylon 6, consists of amide groups along the polymer backbone, with primary amines and carboxylic acid end groups. The analytical separation characteristics of these three amine-based C-CP fiber phases are compared here. Each of the C-CP fiber columns in this study was shown to be able to separate a bovine serum albumin/hemoglobin/lysozyme mixture at high mobile phase linear velocity (∼70 mm s(-1)) but with different elution characteristics. These differences reflect the types of protein-surface interactions that are occurring, based on the active group composition of the fiber surfaces. This study provides important fundamental understanding for the development of surface-modified C-CP fiber columns for protein separation. PMID:26345444

  10. Analytical evaluation of the signal and noise propagation in x-ray differential phase-contrast computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Raupach, Rainer; Flohr, Thomas G, E-mail: rainer.raupach@siemens.com [Siemens AG Healthcare Sector, H IM CT R and D PA, Siemensstrasse 1, D-91301 Forchheim (Germany)

    2011-04-07

    We analyze the signal and noise propagation of differential phase-contrast computed tomography (PCT) compared with conventional attenuation-based computed tomography (CT) from a theoretical point of view. This work focuses on grating-based differential phase-contrast imaging. A mathematical framework is derived that is able to analytically predict the relative performance of both imaging techniques in the sense of the relative contrast-to-noise ratio for the contrast of any two materials. Two fundamentally different properties of PCT compared with CT are identified. First, the noise power spectra show qualitatively different characteristics implying a resolution-dependent performance ratio. The break-even point is derived analytically as a function of system parameters such as geometry and visibility. A superior performance of PCT compared with CT can only be achieved at a sufficiently high spatial resolution. Second, due to periodicity of phase information which is non-ambiguous only in a bounded interval statistical phase wrapping can occur. This effect causes a collapse of information propagation for low signals which limits the applicability of phase-contrast imaging at low dose.

  11. Analytical possibilities of different X-ray fluorescence systems for determination of trace elements in aqueous samples pre-concentrated with carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Marguí, E., E-mail: eva.margui@udg.edu [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Zawisza, B.; Skorek, R. [Institute of Chemistry, University of Silesia, Szkolna 9, 40-006 Katowice (Poland); Theato, T. [SPECTRO Analytical Instruments GmbH, Boschstr. 10, 47533 Kleve (Germany); Queralt, I. [Laboratory of X-Ray Analytical Applications, Institute of Earth Sciences Jaume Almera, CSIC, Solé Sabarís s/n, 08028 Barcelona (Spain); Hidalgo, M. [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Sitko, R. [Institute of Chemistry, University of Silesia, Szkolna 9, 40-006 Katowice (Poland)

    2013-10-01

    This study was aimed to achieve improved instrumental sensitivity and detection limits for multielement determination of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Se, Pb and Cd in liquid samples by using different X-ray fluorescence (XRF) configurations (a benchtop energy-dispersive X-ray fluorescence spectrometer, a benchtop polarised energy-dispersive X-ray fluorescence spectrometer and a wavelength-dispersive X-ray fluorescence spectrometer). The preconcentration of metals from liquid solutions consisted on a solid-phase extraction using carbon nanotubes (CNTs) as solid sorbents. After the extraction step, the aqueous sample was filtered and CNTs with the absorbed elements were collected onto a filter paper which was directly analyzed by XRF. The calculated detection limits in all cases were in the low ng mL{sup −1} range. Nevertheless, results obtained indicate the benefits, in terms of sensitivity, of using polarized X-ray sources using different secondary targets in comparison to conventional XRF systems, above all if Cd determination is required. The developed methodologies, using the aforementioned equipments, have been applied for multielement determination in water samples from an industrial area of Poland. - Highlights: • Use of carbon nanotubes for preconcentration of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Se, Pb and Cd • Combination of this preconcentration procedure with different XRF systems • Benefit of using polarized X-ray sources for trace element determination.

  12. Semi-analytical model of filtering effects in microwave phase shifters based on semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Chen, Yaohui; Xue, Weiqi; Öhman, Filip;

    2008-01-01

    We present a model to interpret enhanced microwave phase shifts based on filter assisted slow and fast light effects in semiconductor optical amplifiers. The model also demonstrates the spectral phase impact of input optical signals.......We present a model to interpret enhanced microwave phase shifts based on filter assisted slow and fast light effects in semiconductor optical amplifiers. The model also demonstrates the spectral phase impact of input optical signals....

  13. Spectroscopic studies of fluorescent complexes of tyrosine 8-hydroxyquinoline and tyrosine-8-hydroxyquinaldine in aqueous phase

    International Nuclear Information System (INIS)

    A new method has been developed by preparing complexes involving condensation of tyrosine with 8-hydroxyquinoline (Oxine) and 8-hydroxyquinaldine (Quinaldine) respectively, producing fluorescent products. The products obtained have been investigated for identification and quantitative estimation using different spectroscopic techniques including fluorescence activity of newly synthesized products. 8-hydroxyquinaldine and 8-hydroxyquinoline (Oxine) condensed with tyrosine separately produced water soluble fluorescent complexes. The complexes have been investigated for identification and quantitative estimation of amino acids. Identification of amino acids in nano mole or below than nano mole has become possible by present fluorometric activity of these complexes involving different excitation and emission wavelengths. The fluorometric activity of complexes has been observed to be 100 to 1000 times higher than assay method involving ninhydrin and amino acid analyzer. The method adopted in our laboratory is rapid, versatile with good reproducibility and provides excellent results for adoption by analytical, agricultural and biomedical laboratories to estimate amino acids and metals in composite matrix. (author)

  14. A study of iodine, cesium, and strontium sorption on alkali-earth hydro-phosphates from the aqueous phase

    International Nuclear Information System (INIS)

    Full text of publication follows: The amount of radioactive species penetrating into the environment because of human activities has been increasingly growing. The most biologically dangerous nuclear-fuel fission products are iodine, cesium, and strontium radionuclides, which can sorb from aqueous solutions on various natural objects, including apatite minerals. This work studied the sorption of 131I-, 131IO3-137Cs+ and 85Sr2+ ions of various samples of Ca, Sr, and Ba hydro-phosphates. The samples of alkali-earth hydro-phosphates (AEHP) were synthesized by the following reactions: MCl2 + Na3PO4 + NaOH → M5(PO4)3OH↓; MCl2 + NH4OH + (NH4)2HPO4 → M5(PO4)3OH↓; MCl2 + NaOH + (NH4)2HPO4 → M5(PO4)3OH↓ (where M is Ca, Sr, or Ba). The experiments on a study of the sorption of 131I-, 131IO3-137Cs+, and 85Sr2+ ions on AEHP from aqueous solutions of KI, KIO3, CsNO3, or Sr(NO3)2 were carried out using the following procedure. A calculated amount of the target AEHP was added upon mixing to a 1.10-5 mg/dm3 water solution (200 ml) of KI, KIO3, CsNO3, or Sr(NO3)2 containing the radionuclides 131I, 137Cs, and 85Sr. The calculation of the AEHP was carried out based on the condition that the ratio between the volume of the liquid and the weight of the solid phase V/m was equal to 500 or 200 ml/g. The suspension was actively mixed over the necessary period of time, and the precipitate was then filtered off. The precipitate on the filter was washed two times with 50-ml portions of water, which were merged in one fraction with the filtered matter. Following that, the concentrations of 131I, 137Cs and 85Sr radionuclides in the solution and precipitate were measured using a gamma spectrometric study. Using the known V/m ratio and the distribution of radionuclides between the solid and liquid phases, the distribution coefficient Kd was calculated by the formula: Kd = V/m . I1/I2, where I1 and I2 are the concentrations of radionuclides in the solid and liquid phases, respectively

  15. Analytical quality assurance procedures developed for the IAEA's Reference Asian Man Project (Phase 2)

    International Nuclear Information System (INIS)

    Analytical quality assurance procedures adopted for use in the IAEA Co-ordinated Research Project on Ingestion and Organ Content of Trace Elements of Importance in Radiological Protection are designed to ensure comparability of the analytical results for Cs, I, Sr, Th, U and other elements in human tissues and diets collected and analysed in nine participating countries. The main analytical techniques are NAA and ICP-MS. For sample preparation, all participants are using identical food blenders which have been centrally supplied after testing for contamination. For quality control of the analyses, six NIST SRMs covering a range of matrices with certified and reference values for the elements of interest have been distributed. A new Japanese reference diet material has also been developed. These quality assurance procedures are summarized here and new data are presented for Cs, I, Sr, Th and U in the NIST SRMs. (author)

  16. Tetracycline degradation by ozonation in the aqueous phase: Proposed degradation intermediates and pathway

    International Nuclear Information System (INIS)

    During the ozonation of tetracycline (TC) in aqueous media at pHs 2.2 and 7.0, the effects of pH variations, protonation and dissociation of functional groups and variation in free radical exposure were investigated to elucidate the transformation pathway. Liquid chromatography-triple quadrupole mass spectrometry detected around 15 ozonation products, and uncovered their production and subsequent degradation patterns. During ozonation at pH 2.2, the TC degradation pathway was proposed on the basis of the structure, ozonation chemistry and mass spectrometry data of TC. Ozonation of TC at the C11a-C12 and C2-C3 double bonds, aromatic ring and amino group generated products of m/z 461, 477, 509 and 416, respectively. Further ozonation at the above mentioned sites gave products of m/z 432, 480, 448, 525 and 496. The removal of TOC reached a maximum of ∼40% after 2 h of ozonation, while TC was completely removed within 4-6 min at both pHs. The low TOC removal efficiency might be due to the generation of recalcitrant products and the low ozone supply for high TC concentration. Ozonation decreased the acute toxicity of TC faster at pH 7.0 than pH 2.2, but the maximum decrease was only about 40% at both pHs after 2 h of ozonation. In this study, attempts were made to understand the correlation between the transformation products, pathway, acute toxicity and quantity of residual organics in solution. Overall, ozonation was found to be a promising process for removing TC and the products initially generated.

  17. Tetracycline degradation by ozonation in the aqueous phase: Proposed degradation intermediates and pathway

    Energy Technology Data Exchange (ETDEWEB)

    Khan, M. Hammad; Bae, Hyokwan [Water Environment Center, Korea Institute of Science and Technology, 39-1 Hawolgok-Dong, Seongbuk-Gu, Seoul 136-791 (Korea, Republic of); Jung, Jin-Young, E-mail: jinjung@ynu.ac.kr [Department of Environmental Engineering, Yeungnam University, 214-1 Dae-Dong, Gyeongsan-Si, Gyeongsangbuk-Do 712-749 (Korea, Republic of)

    2010-09-15

    During the ozonation of tetracycline (TC) in aqueous media at pHs 2.2 and 7.0, the effects of pH variations, protonation and dissociation of functional groups and variation in free radical exposure were investigated to elucidate the transformation pathway. Liquid chromatography-triple quadrupole mass spectrometry detected around 15 ozonation products, and uncovered their production and subsequent degradation patterns. During ozonation at pH 2.2, the TC degradation pathway was proposed on the basis of the structure, ozonation chemistry and mass spectrometry data of TC. Ozonation of TC at the C11a-C12 and C2-C3 double bonds, aromatic ring and amino group generated products of m/z 461, 477, 509 and 416, respectively. Further ozonation at the above mentioned sites gave products of m/z 432, 480, 448, 525 and 496. The removal of TOC reached a maximum of {approx}40% after 2 h of ozonation, while TC was completely removed within 4-6 min at both pHs. The low TOC removal efficiency might be due to the generation of recalcitrant products and the low ozone supply for high TC concentration. Ozonation decreased the acute toxicity of TC faster at pH 7.0 than pH 2.2, but the maximum decrease was only about 40% at both pHs after 2 h of ozonation. In this study, attempts were made to understand the correlation between the transformation products, pathway, acute toxicity and quantity of residual organics in solution. Overall, ozonation was found to be a promising process for removing TC and the products initially generated.

  18. 1H NMR study of thermotropic phase transition in aqueous polymer solutions

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Hanyková, L.

    Poznan : Adam Mickiewicz University, Poznan, 2002 - (Garsztka, M.; Pisula, D.; Wegorowska, W.). s. 237 [Congress AMPERE: Magnetic Resonance and Related Phenomena /31./. 15.07.2002-19.07.2002, Poznan] R&D Projects: GA AV ČR KSK4050111 Grant ostatní: GA UK(CZ) 164/20B Keywords : 1H NMR * thermotropic phase transition * poly(vinyl methyl ether)/D2O solutions Subject RIV: CD - Macromolecular Chemistry

  19. Linker Length-Dependent Control of Gemini Surfactant Aqueous Lyotropic Gyroid Phase Stability.

    Science.gov (United States)

    Perroni, Dominic V; Baez-Cotto, Carlos M; Sorenson, Gregory P; Mahanthappa, Mahesh K

    2015-03-19

    Network-phase lyotropic liquid crystals (LLCs) derived from the water-directed self-assembly of small molecule amphiphiles comprise a useful class of soft nanomaterials, with wide-ranging applications in structural biology and membrane science. However, few known surfactants enable access to these mesophases over wide temperature and amphiphile concentration phase windows. Recent studies have demonstrated that gemini ("twin tail") dicarboxylate surfactants, in which alkyl carboxylates are covalently linked near the headgroups by a hydrophobic bridge, exhibit increased propensities to form double gyroid network phase LLCs. We demonstrate herein that the lyotropic self-assembly behaviors of gemini dicarboxylates sensitively depend on the linker length, whereby odd-carbon linkers stabilize the double gyroid network LLC over unprecedented amphiphile concentration windows up to ∼45 wt % wide between T ≈ 22-80 °C. These self-assembly phenomena, which arise from the linker length-dependent preferred molecular conformations of these amphiphiles, will broaden the technological applications of these nanostructured LLCs. PMID:26262858

  20. Application of a charge coupled device Raman microscope imaging system for quantitative analysis of aqueous surfactant phases

    International Nuclear Information System (INIS)

    Tile development of the molecular optical laser examiner Raman microprobe during the 70's has provided the ability to acquire analytical quality Raman spectra with spatial resolution of the order of one micron. In recent years, with the introduction of charge coupled device detectors and holographic filters, this technology has become efficient enough to allow spectral mapping experiments to be possible. The main aim of this project was to modify the Jobin Yvon/Spex confocal Raman spectrometer to provide line imaging capabilities and use this feature to provide a rapid means of producing a phase composition diagram of a surface active agent with water. The surfactants chosen for phase behavior were polyoxyethylenes C12H25(OCH2CH2)xOH [C12EO8] and C12H25(OCH2CH2)6OH [C12EO6]. Each solid surfactant was placed at one end in a 0.4 mm pathlength borosilicate cell and water introduced at the other end. The different phases and boundaries were allowed to develop, in the cell by means of the diffuse interfacial transport method at different temperatures. These were then examined by line imaging and their corresponding composition determined using a series of external ethoxylate standards. The resulting phase boundaries were found to be comparable with those obtained using alternative methods, however the time taken to obtain them was considerably reduced. (author)

  1. Analytical closed-form solution of three-phase four-switch PWM rectifier

    Czech Academy of Sciences Publication Activity Database

    Škramlík, Jiří; Valouch, Viktor; Klíma, J.; Pecha, I.

    2010-01-01

    Roč. 55, č. 3 (2010), s. 223-235. ISSN 0001-7043 R&D Projects: GA MPO FT-TA5/123 Institutional research plan: CEZ:AV0Z20570509 Keywords : four-switch PWM rectifier * space vector modulation * closed-form analytical solution Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  2. Production of dry Lactobacillus rhamnosus GG preparations by spray drying and lyophilization in aqueous two-phase systems

    Directory of Open Access Journals (Sweden)

    Katarzyna Leja

    2009-12-01

    Full Text Available Background. Drying is the oldest method of food preservation. It works by removing water from the food, which prevents the growth of microorganisms and decay. Moreover, spray or freeze drying is also used for the preservation of probiotic cultures. The aim of this study was to compare a survival rate of probiotic bacteria Lactobacillus rhamnosus during spray and freeze drying in ATPS. These results were also compared with survival rate of cells dried under the same conditions but suspended only in skim milk, 6% solution of PVP or 6% solution of dextran. Material and methods. The bacteria Lactobacillus rhamnosus GGwere suspended and spray or freeze dried in various types of aqueous two-phase emulsions: PVP/dextran, PEG4000/dextran and PEG8000/dextran. These emulsions consisted of different types of polymers and had varying ratio of polymers in dispersed (dextran and dispersing (PEG and PVP phases. Results. The research demonstrated that survival rate of bacteria directly after drying depended mainly on protective reagent, rather than on drying method. After 30-day-storage of the dried bacteria cell specimens, the highest survival rate was noted in case of freeze dried cells in milk. In case of spray drying the highest cell survival rate was observed when emulsion PVP3.6%/dextran2.4% was used as a drying medium. Conclusions. Finally, it has been found that cell survival rate was not strongly influenced by the storage temperature of the powder but it depended on the drying medium.  

  3. Purification of C-phycocyanin from Spirulina platensis in aqueous two-phase systems using an experimental design

    Directory of Open Access Journals (Sweden)

    Francine Silva Antelo

    2015-02-01

    Full Text Available C-phycocyanin from Spirulina platensis was purified in aqueous two-phase systems (ATPS of polyethylene glycol (PEG/potassium phosphate, varying the molar mass of the PEG. Results using a full factorial design showed that an increase in the concentration of salt and decrease in the concentration of PEG caused an increment in the purification factor for all the ATPS studied. Optimization of the conditions of the purification was studied using a central composite rotatable design for each molar mass of PEG. The ATPS composed of 7% (w/w PEG 1500 or 4% (w/w PEG 8000 (g/gmol and 23 or 22.5% (w/w of phosphate resulted a purification factor of 1.6-fold for C-phycocyanin, with total and 57% recovery, respectively. Process conditions were optimized for the purification factor for the system with PEG 1500. The ATPS with 4% (w/w PEG 4000 or 4% (w/w PEG 6000 and 21% (w/w phosphate resulted purification factors of 2.1 and 2.2-fold, recovering 100% and 73.5%, respectively of C-phycocyanin in the top phase.

  4. EFFECT OF AQUEOUS PHASE PROPERTIES ON CLAY PARTICLE ZETA POTENTIAL AND ELECTRO-OSMOTIC PERMEABILITY: IMPLICATIONS FOR ELECTRO-KINETIC SOIL REMEDIATION PROCESSES

    Science.gov (United States)

    The influence of aqueous phase properties (pH, ionic strength and divalent metal ion concentration) on clay particle zeta potential and packed-bed electro-osmotic permeability was quantified. Although pH strongly altered the zeta potential of a Georgia kaolinite, it did not signi...

  5. INVESTIGATION INTO THE RATE OF TRIOCTYLAMINE PARTITIONING INTO THE MCU AQUEOUS PHASES

    Energy Technology Data Exchange (ETDEWEB)

    Peters, T.; Couture, A.

    2013-07-16

    The Savannah River National Laboratory (SRNL) has examined the issue of trioctylamine (TOA) losses at the Modular Caustic-Side Solvent Extraction Unit (MCU) solvent. For this study, SRNL used partitioning and radiolysis data from the Oak Ridge National Laboratory (ORNL) as well as actual MCU operational data. From the radiolysis data, SRNL prepared a model on the rate of TOA degradation. From the combined sets of data, SRNL has calculated the largest possible value of TOA (although this value is not credible) in the Strip Effluent (SE) and also calculated two different conservative, more realistic values for TOA in the SE. Even under conservative assumptions, such as all of the TOA losses partitioning solely into the Strip Effluent (SE), the MCU operational data suggests that the maximum realistic TOA concentration in the SE is < 0.6 mg/L. Furthermore, from understanding the chemical differences between the old and new strip solutions, SRNL does not believe that the TOA will deplete from the blended BOBCalixC6 – Next Generation Solvent (NGS-MCU) at a rate higher than previously experienced. Finally, SRNL recommends pursuing analytical development of a method for TOA with a superior precision compared to the current method. However, as the TOA in the blended solvent will continuously decline during MCU operations, further improvements in the development of the understanding of TOA losses may not be cost effective.

  6. Synthesis, characterization and study of arsenate adsorption from aqueous solution by α- and δ-phase manganese dioxide nanoadsorbents

    International Nuclear Information System (INIS)

    Single-phase α-MnO2 nanorods and δ-MnO2 nano-fiber clumps were synthesized using manganese pentahydrate in an aqueous solution. These nanomaterials were characterized using the Transmission Electron Microscope (TEM), Field Emission Scanning Electron Microscope (FE-SEM), Powder X-ray diffraction (XRD) and the Brunauer-Elmet-Teller nitrogen adsorption technique (BET-N2 adsorption). The structural analysis shows that α-MnO2 (2x2 tunnel structure) has the form of needle-shaped nanorods and δ-MnO2 (2D-layered structure) consists of fine needle-like fibers arranged in ball-like aggregates. Batch adsorption experiments were carried out to determine the effect of pH on adsorption kinetics and adsorption capacity for the removal of As(V) from aqueous solution onto these two types of nanoadsorbents. The adsorption capacity of As(V) was found to be highly pH dependent. The adsorption of As(V) onto α-MnO2 reached equilibrium more rapidly with higher adsorption capacity compared to δ-MnO2. -- Graphical abstract: α-MnO2 (2x2 tunnel structure) nanorods and δ-MnO2 (2-D layered structure) nano-fiber clumps were synthesized in a facile way in an aqueous solution and characterized by TEM, FE-SEM, XRD and BET-N2 adsorption techniques. The structural analysis shows that α-MnO2 is needle shaped nanorods and δ-MnO2 consists of 2-D platelets of fine needle-like fibers arranged in ball-like aggregates. Further batch experiments confirmed that both nanoadsorbents are potential candidates for the adsorption of As(V) with a capacity of 19.41 and 15.33 mg g-1 for α-MnO2 and δ-MnO2, respectively. The presence of As3d peak in XPS study indicates that arsenic on the surface of nanoadsorbents is in the stable form of As(V) with a percentage of arsenate onto α-MnO2 is 0.099% as compared to 0.021% onto δ-MnO2, clearly indicating the higher adsorption of As(V) in case of α-MnO2 as compared to δ-MnO2, which is in good agreement with the adsorption studies results. Display Omitted

  7. Analytical calculation of the RFOC method in single-phase induction motor

    Science.gov (United States)

    Jannati, M.; Monadi, A.; Idris, N. R. N.; Faudzi, A. A. M.

    2016-05-01

    This study discusses the different techniques for speed control of single-phase induction motor with two asymmetrical main and auxiliary windings based on Rotor Field-Oriented Control (RFOC) method. In the presented methods, transformation matrices are introduced and applied to the equations of single-phase induction motor. It is shown by applying these rotational transformations to the unbalanced equations of single-phase induction motor, equations of single-phase induction motor are transformed into symmetrical equations. These rotational transformations are achieved based from the steady-state equivalent circuit of single-phase induction motor. Finally, a method for RFOC of single-phase induction motor is proposed. Results show the good performance of the proposed method.

  8. Use of a Combined Technology of Ultrasonication, Three-Phase Partitioning, and Aqueous Enzymatic Oil Extraction for the Extraction of Oil from Spirogyra sp.

    OpenAIRE

    Adisheshu Reddy; Majumder, Abir B

    2014-01-01

    Algal oil from Spirogyra sp. was extracted using a combined technology of ultrasonication, three-phase partitioning, and aqueous enzymatic oil extraction. Ultrasonication was done to rupture the cell wall and papain was used for an easier release of the trapped oil. The salt concentration for three-phase partitioning, preincubation period with (or without) the protease, and its operational temperature were optimized for a maximum possible yield of the oil and the effect of ultrasonication, an...

  9. Equilibrium partial pressures, thermodynamic properties of aqueous and solid phases, and Cl{sub 2} production from aqueous HCl and HNO{sub 3} and their mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Massucci, M.; Clegg, S.L.; Brimblecombe, P. [Univ. of East Anglia, Norwich (United Kingdom). School of Environmental Sciences

    1999-05-27

    Equilibrium total pressures have been measured above aqueous HNO{sub 3} and aqueous HCl using a capacitance manometer. Equilibrium partial pressures of the acids have also been determined, by mass spectrometry, from 274.8 to 234.6 K for both HCl solutions, and from 265.0 to 240.1 K for 15.73 mol kg{sup {minus}1} HNO{sub 3}. Results are generally consistent with model predictions, though with small systematic deviations for the total pressure measurements over aqueous HCl at about 220 K. Mixtures of HCl{minus}HNO{sub 3}{minus}H{sub 2}O composition yielded measured total pressures orders of magnitude greater than predicted for the gases H{sub 2}O, HNO{sub 3}, and HCl. Mass spectrometric determinations and equilibrium thermodynamic calculations suggest that Cl{sub 2} and NOCl were produced by the reaction: 4H{sup +}{sub aq} + NO{sub 3}{sup {minus}}{sub aq} + 3Cl{sup {minus}}{sub aq} {r_equilibrium} NOCl{sub aq} + Cl{sub 2(aq)} + 2H{sub 2}O{sub (1)}, which is known to occur in aqua regia. Calculations for aqueous solutions of stratospheric aerosol composition suggest, purely on equilibrium grounds, that the reaction could be a source of active chlorine in the stratosphere. The correlation of Clegg and Brimblecombe of the thermodynamic properties of aqueous HNO{sub 3} activities has been revised, and vapor pressure products assessed from literature studies. The activity product for the reaction HNO{sub 3}{center_dot}2H{sub 2}O{sub (cr)} {r_equilibrium} H{sup +}{sub (aq)} + NO{sub 3}{sup {minus}}{sub (aq)} + 2H{sub 2}O{sub (1)} has also been determined. The model of Carslaw et al. has been revised for the solubility of HBr in aqueous H{sub 2}SO{sub 4} to stratospheric temperatures.

  10. Phase diagrams and water activities of aqueous ammonium salts of malonic acid.

    Science.gov (United States)

    Beyer, Keith D; Richardson, Michael; Reusch, Breanna

    2011-04-14

    Malonic acid has been observed in the free troposphere and as a component of tropospheric aerosol, among other dicarboxylic acids. These aerosols can uptake ammonia, which partially or completely neutralizes the acids. Therefore, the impact of ammoniated dicarboxylic acids on the phases that can exist in aerosols at atmospheric temperatures needs investigation. To that end, the low temperature, solid/liquid phase diagrams of ammonium hydrogen malonate/water, ammonium malonate/water, and triammonium hydrogen malonate/water have been investigated with differential scanning calorimetry and infrared spectroscopy of thin films. Results show that the order of increasing solubility is triammonium hydrogen malonate, ammonium hydrogen malonate, malonic acid, and ammonium malonate. We have also determined a hydrate may form in the ammonium malonate system and decompose below 240 K. We report water activities at the ice melting points for each system up to the respective eutectic concentrations, and find for a given mole fraction of water, increasing ammonium content leads to decreasing water activity coefficients. PMID:21428389

  11. Enzymatic synthesis of a novel glycolipid biosurfactant, mannosylerythritol lipid-D and its aqueous phase behavior.

    Science.gov (United States)

    Fukuoka, Tokuma; Yanagihara, Takashi; Imura, Tomohiro; Morita, Tomotake; Sakai, Hideki; Abe, Masahiko; Kitamoto, Dai

    2011-02-01

    Mannosylerythritol lipids (MELs) produced by yeasts are one of the most promising glycolipid biosurfactants. In this study, we succeeded in the preparation of a novel MEL homolog having no acetyl groups, namely MEL-D. MEL-D was synthesized by lipase-catalyzed hydrolysis of acetyl groups from a known MEL, and identified as 4-O-[2',3'-di-O-alka(e)noyl-β-d-mannopyranosyl]-(2R,3S)-erythritol. The obtained MEL-D showed a higher critical aggregation concentration (CAC=1.2 × 10(-5)M) and hydrophilicity compared to known MELs, retaining an excellent surface tension lowering activity (the surface tension at the CAC was 24.5mN/m). In addition, we estimated the binary phase diagram of the MEL-D-water system based on a combination of visual inspection, polarized optical microscopy, and SAXS measurement. From these results, MEL-D was found to self-assemble into a lamellar (L(α)) structure over all ranges of concentration. Meanwhile, the one-phase L(α) region of MEL-D was extended wider than those of known MELs. MEL-D might keep more water between the polar layers in accordance with the extension of the interlayer spacing (d). These results suggest that the newly obtained MEL-D would facilitate the application of MELs in various fields as a lamellar-forming glycolipid with higher hydrate ability. PMID:21163471

  12. Analytical applications of emulsions and microemulsions.

    Science.gov (United States)

    Burguera, José Luis; Burguera, Marcela

    2012-07-15

    Dispersion systems like emulsions and microemulsions are able to solubilize both polar and non-polar substances due to the special arrangement of the oil and aqueous phases. The main advantages of using emulsions or microemulsions in analytical chemistry are that they do not require the previous destruction of the sample matrix or the use of organic solvents as diluents, and behave similarly to aqueous solutions, frequently allowing the use of aqueous standard solutions for calibration. However, it appears that there are many contradictory concepts and misunderstandings often related to terms definition when referring to such systems. The main aim of this review is to outline the differences between these two aggregates and to give an overview of the most recent advances on their analytical applications with emphasis on the potentiality of the on-line emulsification processes. PMID:22817921

  13. pH recycling aqueous two-phase systems applied in extraction of Maitake β-Glucan and mechanism analysis using low-field nuclear magnetic resonance.

    Science.gov (United States)

    Hou, Huiyun; Cao, Xuejun

    2015-07-31

    In this paper, a recycling aqueous two-phase systems (ATPS) based on two pH-response copolymers PADB and PMDM were used in purification of β-Glucan from Grifola frondosa. The main parameters, such as polymer concentration, type and concentration of salt, extraction temperature and pH, were investigated to optimize partition conditions. The results demonstrated that β-Glucan was extracted into PADB-rich phase, while impurities were extracted into PMDM-rich phase. In this 2.5% PADB/2.5% PMDM ATPS, 7.489 partition coefficient and 96.92% extraction recovery for β-Glucan were obtained in the presence of 30mmol/L KBr, at pH 8.20, 30°C. The phase-forming copolymers could be recycled by adjusting pH, with recoveries of over 96.0%. Furthermore, the partition mechanism of Maitake β-Glucan in PADB/PMDM aqueous two-phase systems was studied. Fourier transform infrared spectra, ForteBio Octet system and low-field nuclear magnetic resonance (LF-NMR) were introduced for elucidating the partition mechanism of β-Glucan. Especially, LF-NMR was firstly used in the mechanism analysis in partition of aqueous two-phase systems. The change of transverse relaxation time (T2) in ATPS could reflect the interaction between polymers and β-Glucan. PMID:26094138

  14. Multiresidue analytical method for the simultaneous determination of 72 micropollutants in aqueous samples with ultra high performance liquid chromatography-high resolution mass spectrometry.

    Science.gov (United States)

    Wode, Florian; Reilich, Christa; van Baar, Patricia; Dünnbier, Uwe; Jekel, Martin; Reemtsma, Thorsten

    2012-12-28

    A multiresidue method for the simultaneous quantification of 72 micropollutants in aqueous samples by ultra high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) is described. A variety of substance classes like industrial chemicals, analgesics, anticonvulsants, antihypertensives, psychoactive substances, flame retardants, neutral and acidic pesticides are comprised. A sample volume of 1 mL was enriched by online solid phase extraction (SPE), separated on a 2.6 μm core-shell column and detected with an Exactive™ high resolution mass spectrometer. Simultaneous determination of compounds with different ionization behavior was achieved by polarity switching. One complete run lasted 15 min. The method was validated in the matrices drinking water (DW), diluted surface water (dSW) and diluted waste water treatment plant effluent (dWW) by analyzing 10 replicates spiked at two concentration levels. Limits of quantification (LOQs) ranged between 0.01 and 0.06 μg/L in DW, 0.03 and 0.38 μg/L in dSW, 0.06 and 0.38 μg/L in dWW. The accuracies were between 77 and 117% in DW, 70 and 121% in dSW, 71 and 121% in dWW for both spike levels, respectively. Five compounds in dSW and one compound in dWW were affected by matrix effects, leading to accuracies outside the ranges stated above. The precision for level 2 was excellent with relative standard deviations (RSDs) between 2.2 and 6.5% in DW, 0.5 and 4.9% in dSW and between 1.2 and 6.6% in dWW. PMID:23182284

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

    Science.gov (United States)

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

    2015-05-15

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

  16. Evaluating the potential for quantitative monitoring of in situ chemical oxidation of aqueous-phase TCE using in-phase and quadrature electrical conductivity

    Science.gov (United States)

    Hort, R. D.; Revil, A.; Munakata-Marr, J.; Mao, D.

    2015-07-01

    Electrical resistivity measurements can potentially be used to remotely monitor fate and transport of ionic oxidants such as permanganate (MnO4-) during in situ chemical oxidation (ISCO) of contaminants like trichloroethene (TCE). Time-lapse two-dimensional bulk conductivity and induced polarization surveys conducted during a sand tank ISCO simulation demonstrated that MnO4- plume movement could be monitored in a qualitative manner using bulk conductivity tomograms, although chargeability was below sensitivity limits. We also examined changes to in-phase and quadrature electrical conductivity resulting from ion injection, MnO2 and Cl- production, and pH change during TCE and humate oxidation by MnO4- in homogeneous aqueous solutions and saturated porous media samples. Data from the homogeneous samples demonstrated that inversion of the sand tank resistivity data using a common Tikhonov regularization approach was insufficient to recover an accurate conductivity distribution within the tank. While changes to in-phase conductivity could be successfully modeled, quadrature conductivity values could not be directly related to TCE oxidation product or MnO4- concentrations at frequencies consistent with field induced polarization surveys, limiting the utility of quadrature conductivity for monitoring ISCO.

  17. THREE-WAY-CATALYTIC CONVERTERS: ANALYTICAL INVESTIGATION OF A TWO-PHASE MODELL I. SEPARATION METHOD

    OpenAIRE

    Volkmann, J.; Migranov, N.

    2010-01-01

    The two-phase-model describes the thermal and chemical behaviour of a three-way-catalytic onverter (TWC). According to this model energy, mass balance equations for gas and solid phase are taking into account. These equations are investigated by the separation of variables method in order to construct solutions.

  18. Experimental measurement and thermodynamic modelling of phase equilibria of semi-clathrate hydrates of (CO2 + tetra-n-butyl-ammonium bromide) aqueous solution

    International Nuclear Information System (INIS)

    Highlights: • Hydrate phase equilibrium data are reported for the CO2 + TBAB aqueous solutions systems. • A thermodynamic model is developed to predict the dissociation conditions of the latter systems. • The properties of the aqueous phase are calculated using the AMSA-NRTL electrolyte model. • The model satisfactorily predicts the experimental data with an AARD% of approximately 13%. - Abstract: Comprehensive studies on semi-clathrate hydrates phase equilibria are still required to better understand characteristics of this type of clathrates. In this communication, new experimental data on the dissociation conditions of semi-clathrate hydrates of {carbon dioxide + tetra-n-butyl-ammonium bromide (TBAB)} aqueous solution are first reported in a wide range of TBAB concentrations and at different pressures and temperatures. A thermodynamic model is then proposed to predict the dissociation conditions of the semi-clathrate hydrates for the latter system. The (hydrate + TBAB) aqueous solution (H + Lw) phase equilibrium prediction is considered based on Gibbs free energy minimization approach. A modified van der Waals–Platteeuw solid solution theory developed based on the (H + Lw) equilibrium information is employed to predict the dissociation conditions of semi-clathrate hydrates of carbon dioxide + TBAB. The properties of the aqueous solution are estimated using the AMSA-NRTL electrolyte model (considering the association and hydration of ions). The Peng–Robinson equation of state is used for estimating the gas/vapour phase properties. Results show that the proposed model satisfactorily predicts the experimental values with an average absolute relative deviation of approximately 13%

  19. Extraction of natural red colorants from the fermented broth of Penicillium purpurogenum using aqueous two-phase polymer systems.

    Science.gov (United States)

    Santos-Ebinuma, Valéria Carvalho; Lopes, André Moreni; Pessoa, Adalberto; Teixeira, Maria Francisca Simas

    2015-01-01

    Safety concerns related to the increasing and widespread application of synthetic coloring agents have increased the demand for natural colorants. Fungi have been employed in the production of novel and safer colorants. In order to obtain the colorants from fermented broth, suitable extraction systems must be developed. Aqueous two-phase polymer systems (ATPPS) offer a favorable chemical environment and provide a promising alternative for extracting and solubilizing these molecules. The aim of this study was to investigate the partitioning of red colorants from the fermented broth of Penicillium purpurogenum using an ATPPS composed of poly(ethylene glycol) (PEG) and sodium polyacrylate (NaPA). Red colorants partitioned preferentially to the top (PEG-rich phase). In systems composed of PEG 6,000 g/mol/NaPA 8,000 g/mol, optimum colorant partition coefficient (KC ) was obtained in the presence of NaCl 0.1 M (KC  = 10.30) while the PEG 10,000 g/mol/NaPA 8,000 g/mol system in the presence of Na2 SO4 0.5 M showed the highest KC (14.78). For both polymers, the mass balance (%MB) and yield in the PEG phase (%ηTOP ) were close to 100 and 79%, respectively. The protein selectivity in all conditions evaluated ranged from 2.0-3.0, which shows a suitable separation of the red colorants and proteins present in the fermented broth. The results suggest that the partitioning of the red colorants is dependent on both the PEG molecular size and salt type. Furthermore, the results obtained support the potential application of ATPPS as the first step of a purification process to recover colorants from fermented broth of microorganisms. PMID:26097197

  20. Phase transitions of aqueous atmospheric particles: Crystallization of ammonium salts promoted by oxide mineral constituents

    Science.gov (United States)

    Han, Jeong-Ho

    2001-09-01

    Knowledge of the hygroscopic response of aerosols is a fundamental factor necessary for the accurate quantitative modeling of visibility degradation, global warming, PM-10 health issues, cloud microphysics, and the oxidizing capacity of the troposphere. At the present time, however, our current understanding of phase transitions is insufficient to develop accurate quantitative models. The discrepancy between current atmospheric models and field measurements originates mainly from a lack of understanding of the efflorescence of real atmospheric particles. While there have been many studies on the homogeneous nucleation of the soluble organic, inorganic, or multi-component materials, many recent in situ field measurements with single-particle mass spectrometry reveal that the individual particles in the troposphere are primarily composed of more than one component. One of the common mixed component particle types contains both water- soluble and insoluble components. Through atmospheric processes, the soluble component can be expected to form a coating around the insoluble constituents. This type of atmospheric particles is very important because the insoluble constituent can play a role as a template for the crystallization of the soluble components by heterogeneous nucleation. In the atmosphere, the most prevalent insoluble constituents are mineral dusts, which have their origin from Saharan and Gobbi deserts. The existence of these coated particles has been supported by several field measurements as well as model studies. Therefore, it becomes imperative to simulate more realistic atmospheric particles for more exact (or realistic) understanding the phase transition of the ambient aerosol particles in the real world. In this context, a series of studies has been completed to solve the aforementioned problems in the phase transition study and to better understand the heterogeneous nucleation of these internally mixed particles. An in-line tube furnace has been

  1. Supercritical fluid chromatography with ionic liquid stationary phases: Practical experience with determination of analyte distribution constants

    Czech Academy of Sciences Publication Activity Database

    Planeta, Josef; Karásek, Pavel; Roth, Michal

    Pardubice: Univerzita Pardubice, 2005 - (Jandera, P.). s. 186-187 ISBN 80-7194-771-7. [International Symposium on Separation Sciences (ISSS 2005) /11./. 12.09.2005-14.09.2005, Pardubice] R&D Projects: GA AV ČR IAA4031301; GA AV ČR KJB400310504; GA ČR GA203/05/2106 Keywords : ionic liquid * supecritical carbon dioxide * capillary-column chromatography Subject RIV: CB - Analytical Chemistry, Separation

  2. Analytical Modeling and Implementation of Three-Phase Four-Switch Space-Vector PWM Converter

    Czech Academy of Sciences Publication Activity Database

    Paclt, Zdeněk; Šimek, Petr; Škramlík, Jiří; Valouch, Viktor; Klíma, J.

    Prague : Institute of Thermomechanics AS CR, v. v. i., 2008, s. 49-52. ISBN 978-80-87012-13-0. [Symposium Electric Machines and Drives, Power Electronics and Drive Control. Prague (CZ), 30.09.2008-02.10.2008] R&D Projects: GA AV ČR IAA200760703 Institutional research plan: CEZ:AV0Z20570509 Keywords : four-switch PWM rectifier * space vector modulation * closed-form analytical solution Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  3. An example of transition from a corrosion process in gaseous phase to corrosion in aqueous environment: the case of Z2CN18-10 stainless steel by iodine and water in vapour phase

    International Nuclear Information System (INIS)

    This research thesis addresses an example of transition of a corrosion process in gaseous phase towards corrosion in aqueous environment, specifically in the case of the corrosion of the Z2CN18-10 stainless steel by gaseous iodine in presence of water vapour (and possibly nitrogen dioxide). This transition occurs in two steps: initiation in gaseous phase and growth in aqueous environment. This transition is due to hygroscopic properties of mostly chromium iodides and, to a lesser extent, iron iodides. Morphological, electrochemical and thermogravimetry studies have been performed by varying different parameters governing corrosion processes: corrosion temperature, iodine concentration, relative humidity, and reaction time

  4. Interpretation of in-phase and out-of-phase BWR oscillations using an extended reduced order model and semi-analytical bifurcation analysis

    International Nuclear Information System (INIS)

    An extended reduced order model is presented and applied to analyze global and regional oscillations in BWRs. Stability and semi-analytical bifurcation analyses are performed using this model in conjunction with the bifurcation code BIFDD to determine the stability limits for both in-phase and out-of-phase oscillation modes and the nature of Poincare-Andronov-Hopf bifurcation. The results obtained show that both sub- and supercritical PAH bifurcations are encountered in different regions of the parameter space. An in-depth investigation of the properties of the elements of the eigenvectors associated with these two modes of oscillation is carried out. Results show that these eigenvectors provide information as regards the corresponding oscillation mode (in-phase or out-of-phase) without solving the set of system ODEs. The analysis clearly brings out the fact that in-phase and out-of-phase oscillations are whole-system mechanisms. A clear distinction is thereby made between these oscillation modes, on the one hand, and the fundamental and first azimuthal neutronics modes on the other hand

  5. Dissolution of metal oxides in an acid-saturated ionic liquid solution and investigation of the back-extraction behaviour to the aqueous phase

    OpenAIRE

    Wellens, Sil; Vander Hoogerstraete, Tom; Möller, Claudia; Thijs, Ben; Luyten, Jan; Binnemans, Koen

    2014-01-01

    The dissolution of metal oxides in an acid-saturated ionic liquid, followed by selective stripping of the dissolved metal ions to an aqueous phase is proposed as a new ionometallurgical approach for the processing of metals in ionic liquids. The hydrophobic ionic liquid trihexyl(tetradecyl)phosphonium chloride (Cyphos IL 101) saturated with a concentrated aqueous hydrochloric acid solution was used to dissolve CaO, NiO, MnO, CoO, CuO, ZnO and Fe2O3. It was found that nickel(II) and calcium...

  6. Countercurrent Chromatographic Separation of Lipophilic Ascorbic Acid Derivatives and Extract from Kadsura Coccinea Using Hydrophobic Organic-Aqueous Two-Phase Solvent Systems

    OpenAIRE

    Shinomiya, Kazufusa; Li, Heran; Kitanaka, Susumu; Ito, Yoichiro

    2009-01-01

    Countercurrent chromatographic (CCC) separation of lipophilic ascorbic acid derivatives and the crude extract from Kadsura Coccinea was performed using the type-J multilayer coil planet centrifuge with a hydrophobic organic-aqueous two-phase solvent system composed of n-hexane/ethyl acetate/ethanol/aqueous 0.1% trifluoroacetic acid at the volume ratio of (5 : 5 : 6 : 2). The lipophilic ascorbic acid derivatives were separated in the order of L-ascrobyl 2,6-dibutyrate, L-ascorbyl 6-palmitate a...

  7. Semi-analytic calculation of the gravitational wave signal from the electroweak phase transition for general quartic scalar effective potentials

    International Nuclear Information System (INIS)

    Upcoming gravitational wave (GW) detectors might detect a stochastic background of GWs potentially arising from many possible sources, including bubble collisions from a strongly first-order electroweak phase transition. We investigate whether it is possible to connect, via a semi-analytical approximation to the tunneling rate of scalar fields with quartic potentials, the GW signal through detonations with the parameters entering the potential that drives the electroweak phase transition. To this end, we consider a finite temperature effective potential similar in form to the Higgs potential in the Standard Model (SM). In the context of a semi-analytic approximation to the three dimensional Euclidean action, we derive a general approximate form for the tunneling temperature and the relevant GW parameters. We explore the GW signal across the parameter space describing the potential which drives the phase transition. We comment on the potential detectability of a GW signal with future experiments, and physical relevance of the associated potential parameters in the context of theories which have effective potentials similar in form to that of the SM. In particular we consider singlet, triplet, higher dimensional operators, and top-flavor extensions to the Higgs sector of the SM. We find that the addition of a temperature independent cubic term in the potential, arising from a gauge singlet for instance, can greatly enhance the GW power. The other parameters have milder, but potentially noticeable, effects

  8. DISTRIBUTION OF ACTINIDES BETWEEN THE AQUEOUS AND ORGANIC PHASES IN THE TALSPEAK PROCESS

    Energy Technology Data Exchange (ETDEWEB)

    Rudisill, T.; Kyser, E.

    2010-09-02

    One objective of the US Department of Energy's Office of Nuclear Energy (DOE-NE) is the development of sustainable nuclear fuel cycles which improve uranium resource utilization, maximize energy generation, minimize waste generation, improve safety, and complement institutional measures limiting proliferation risks. Activities in progress which support this objective include the development of advanced separation technologies to recover the actinides from used nuclear fuels. With the increased interest in the development of technology to allow closure of the nuclear fuel cycle, the TALSPEAK process is being considered for the separation of Am and Cm from the lanthanide fission products in a next generation reprocessing plant. However, at this time, the level of understanding associated with the chemistry and the control of the process variables is not acceptable for deployment of the process on an industrial scale. To address this issue, DOE-NE is supporting basic scientific studies focused on the TALSPEAK process through its Fuel Cycle Research and Development (R&D) program. One aspect of these studies is an experimental program at the Savannah River National Laboratory (SRNL) in which temperature-dependent distribution coefficients for the extraction of actinide elements in the TALSPEAK process were measured. The data were subsequently used to calculate conditional enthalpies and entropies of extraction by van't Hoff analysis to better understand the thermodynamic driving forces for the TALSPEAK process. In the SRNL studies, the distribution of Pu(III) in the TALSPEAK process was of particular interest. A small amount of Pu(III) would be present in the feed due to process losses and valence adjustment in prior recovery operations. Actinide elements such as Np and Pu have multiple stable oxidation states in aqueous solutions; therefore the oxidation state for these elements must be controlled in the TALSPEAK process, as the extraction chemistry is

  9. Directly light scattering imaging of the aggregations of biopolymer bound chromium(III) hydrolytic oligomers in aqueous phase and liquid/liquid interface

    International Nuclear Information System (INIS)

    Investigations of inorganic oligomers are important in both chemistry and physiology. In this contribution, we propose a laser induced light scattering imaging (LSI) and a total internal reflected light scattering imaging (TIR-LSI) technique, and apply them to characterize the interactions of inorganic oligomers with biopolymer in aqueous phase and at liquid/liquid interface, respectively. In aqueous medium, synthetic chromium(III) hydrolytic oligomers (CrHO) react with DNA, and the resultant binary could be extracted into the H2O/CCl4 interface in the presence of triocyctyl phosphine oxide (TOPO), forming a DNA-CrHO-TOPO ternary amphipathic complex at the interface with the associate constant of 1.32 x 103 mol-1 dm4 for a given 1.0 x 10-4 mol l-1 TOPO. Under the excitation of a 441-nm He-Cd laser light beam, the resultant light scattering and total internal reflected light scattering (TIR-LS) signals of the formed binary in aqueous phase and ternary at liquid/liquid interface could be easily captured using a common microscope coupled with a CCD camera. By digitally analyzing the CCD captures, we demonstrate that aggregations of the CrHO-DNA binary in aqueous phase and DNA-CrHO-TOPO ternary at liquid/liquid interface have occurred, respectively

  10. Analytical Assessment of the Q-Factor due to Cross-Phase Modulation (XPM)

    Institute of Scientific and Technical Information of China (English)

    Stephan; Pachnicke; Edgar; Voges

    2003-01-01

    The paper describes the impact of cross-phase modulation on NRZ modulated WDM systems. The impairments due to XPM will be related to a Q-factor and the effects of dispersion management will be covered.

  11. Analytical electron microscope study of the omega phase transformation in a zirconium-niobium alloy

    International Nuclear Information System (INIS)

    The study of the as-quenched omega phase morphology shows that the domain size of Zr-15% Nb is on the order of 30 A. No alignment of omega domains along β directions was observed and samples having undergone thermal cycling in thin foil form, did not develop a long-period structure of alternating β and ω phases below the omega transformation temperature

  12. Analytical electron microscope study of the omega phase transformation in a zirconium-niobium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zaluzec, N. J.

    1979-01-01

    The study of the as-quenched omega phase morphology shows that the domain size of Zr-15% Nb is on the order of 30 A. No alignment of omega domains along <222>..beta.. directions was observed and samples having undergone thermal cycling in thin foil form, did not develop a long-period structure of alternating ..beta.. and ..omega.. phases below the omega transformation temperature. (FS)

  13. Partitioning of chloroaromatic compounds between the aqueous phase and dissolved and particulate soil organic matter at chlorophenol contaminated sites

    Energy Technology Data Exchange (ETDEWEB)

    Frankki, Sofia [Department of Forest Ecology, Swedish University of Agricultural Sciences, SE-901 83 Umea (Sweden); Persson, Ylva [Environmental Chemistry, Department of Chemistry, Umea University, SE-901 87 Umea (Sweden); Shchukarev, Andrei [Inorganic Chemistry, Department of Chemistry, Umea University, SE-901 87 Umea (Sweden); Tysklind, Mats [Environmental Chemistry, Department of Chemistry, Umea University, SE-901 87 Umea (Sweden); Skyllberg, Ulf [Department of Forest Ecology, Swedish University of Agricultural Sciences, SE-901 83 Umea (Sweden)]. E-mail: ulf.skyllberg@sek.slu.se

    2007-07-15

    The retention and mobility of hydrophobic organic contaminants (HOCs) in soil is mainly determined by hydrophobic partitioning to dissolved and particulate organic matter (DOM and POM, respectively). The aqueous phase, DOM, and POM fractions were extracted and separated from soils at three sites contaminated with technical chlorophenol formulations. Concentrations of chlorophenols (CP), polychlorinated phenoxyphenols (PCPP), polychlorinated diphenyl ethers (PCDE) and polychlorinated dibenzo-p-dioxins and furans (PCDD/F) were determined. The partitioning to POM, in relation to DOM, increased in all three soils with increasing hydrophobicity in the order CP < PCPP {approx} PCDE {approx} PCDF < PCDD. Differences in partitioning to DOM (log K {sub DOC}) and POM (log K {sub POC}) could not be explained by differences in gross organic C chemistry. Black carbon did not contribute significantly to the sorption of PCDDs, whereas >70% wood fibre in one soil resulted in a decrease of log K {sub POC} of 0.5 units for CPs and PCDDs. We conclude that log K {sub OC} for both DOM and POM need to be explicitly determined when the retention and mobility of HOCs is described and modelled in soils. - Increasing hydrophobicity of organic compounds increases the partitioning to particulate natural organic matter relative to dissolved natural organic matter.

  14. Partitioning of chloroaromatic compounds between the aqueous phase and dissolved and particulate soil organic matter at chlorophenol contaminated sites

    International Nuclear Information System (INIS)

    The retention and mobility of hydrophobic organic contaminants (HOCs) in soil is mainly determined by hydrophobic partitioning to dissolved and particulate organic matter (DOM and POM, respectively). The aqueous phase, DOM, and POM fractions were extracted and separated from soils at three sites contaminated with technical chlorophenol formulations. Concentrations of chlorophenols (CP), polychlorinated phenoxyphenols (PCPP), polychlorinated diphenyl ethers (PCDE) and polychlorinated dibenzo-p-dioxins and furans (PCDD/F) were determined. The partitioning to POM, in relation to DOM, increased in all three soils with increasing hydrophobicity in the order CP DOC) and POM (log K POC) could not be explained by differences in gross organic C chemistry. Black carbon did not contribute significantly to the sorption of PCDDs, whereas >70% wood fibre in one soil resulted in a decrease of log K POC of 0.5 units for CPs and PCDDs. We conclude that log K OC for both DOM and POM need to be explicitly determined when the retention and mobility of HOCs is described and modelled in soils. - Increasing hydrophobicity of organic compounds increases the partitioning to particulate natural organic matter relative to dissolved natural organic matter

  15. Structural mechanisms of the Ih–II and II → Ic transitions between the crystalline phases of aqueous ice

    Energy Technology Data Exchange (ETDEWEB)

    Zheligovskaya, E. A., E-mail: lmm@phyche.ac.ru [Russian Academy of Sciences, Frumkin Institute of Physical Chemistry and Electrochemistry (Russian Federation)

    2015-09-15

    Structural mechanisms are proposed for experimentally observed phase transitions between crystalline modifications of aqueous ice, Ih and II, as well as II and Ic. It is known that the Ih–II transition occurs with the conservation of large structural units (hexagonal channels) common for these ices. It is shown that the Ih → II transition may occur with the conservation of 5/6 of all hydrogen bonds in crystal, including all hydrogen bonds in the retained channels (3/4 of the total number of bonds in crystal) and 1/3 of the bonds between these channels (1/12 of the total number). The transformation of other hydrogen bonds between the retained channels leads to the occurrence of proton order in ice II. A structural mechanism is proposed to explain the transformation of single crystals of ice Ih either into single crystals of ice II or into crystalline twins of ice II with c axes rotated by 180° with respect to each other, which is often observed at the Ih → II transition. It is established that up to 7/12 of all hydrogen bonds are retained at the irreversible cooperative II → Ic transition.

  16. Electrodeposited ZnO/ Zn Photo catalysts for the Degradation of Benzene-Toluene-Xylene Mixture in Aqueous Phase

    International Nuclear Information System (INIS)

    The recognition of the ability of volatile organic compounds, (VOCs) to pollute the ground water is now well documented. VOCs such as benzene, toluene and xylene from the petroleum industries processed water leaked through the underground old piping system into the soils and groundwater during its transportation to the wastewater plant. Photo catalysis have been used as a potential system in the degradation of VOCs in the wastewater. However, the powdered form photo catalysts that were used in various studies are difficult to be separated from the aqueous solution at the end of the treatment. Therefore, the main objective of this research is to prepare the electrodeposited photo catalysts for the degradation of aromatic hydrocarbon mixture, benzene-toluene-xylene (BTX) solution under UV light (354 nm). The concentrations of electrolyte and electrodeposition voltages used to prepare the photo catalysts were studied for their efficiency in the degradation. From the research, ZnO/ Zn prepared in 0.8 M NaOH and under 12 V possessed the best catalytic degradation performance by degrading 32.37 % of BTX in the solution. The ZnO/ Zn photo catalyst was characterized using X-ray Diffraction Techniques (XRD) which illustrated high crystallinity of Zn species and reasonably high amorphous phase of ZnO species. (author)

  17. Separation of porcine parvovirus from bovine serum albumin using PEG-salt aqueous two-phase system.

    Science.gov (United States)

    Vijayaragavan, K Saagar; Zahid, Amna; Young, Jonathan W; Heldt, Caryn L

    2014-09-15

    Vaccine production faces a challenge in adopting conventional downstream processing steps that can efficiently purify large viral particles. Some major issues that plague vaccine purification are purity, potency, and quality. The industry currently considers 30% as an acceptable virus recovery for a vaccine purification process, including all downstream processes, whereas antibody recovery from CHO cell culture is generally around 80-85%. A platform technology with an improved virus recovery would revolutionize vaccine production. In a quest to fulfill this goal, we have been exploring aqueous two-phase systems (ATPSs) as an optional mechanism to purify virus. ATPS has been unable to gain wide implementation mainly due to loss of virus infectivity, co-purification of proteins, and difficulty of polymer recycling. Non-enveloped viruses are chemically resistant enough to withstand the high polymer and salt concentrations that are required for effective ATPS separations. We used infectious porcine parvovirus (PPV), a non-enveloped, DNA virus as a model virus to test and develop an ATPS separation method. We successfully tackled two of the three main disadvantages of ATPS previously stated; we achieved a high infectious yield of 64% in a PEG-citrate ATPS process while separating out the main contaminate protein, bovine serum albumin (BSA). The most dominant forces in the separation were biomolecule charge, virus surface hydrophobicity, and the ATPS surface tension. Highly hydrophobic viruses are likely to benefit from the discovered ATPS for high-purity vaccine production and ease of implementation. PMID:25086421

  18. Valorisation of Vietnamese Rice Straw Waste: Catalytic Aqueous Phase Reforming of Hydrolysate from Steam Explosion to Platform Chemicals

    Directory of Open Access Journals (Sweden)

    Cao Huong Giang

    2014-12-01

    Full Text Available A family of tungstated zirconia solid acid catalysts were synthesised via wet impregnation and subsequent thermochemical processing for the transformation of glucose to 5-hydroxymethylfurfural (HMF. Acid strength increased with tungsten loading and calcination temperature, associated with stabilisation of tetragonal zirconia. High tungsten dispersions of between 2 and 7 W atoms·nm−2 were obtained in all cases, equating to sub-monolayer coverages. Glucose isomerisation and subsequent dehydration via fructose to HMF increased with W loading and calcination temperature up to 600 °C, indicating that glucose conversion to fructose was favoured over weak Lewis acid and/or base sites associated with the zirconia support, while fructose dehydration and HMF formation was favoured over Brönsted acidic WOx clusters. Aqueous phase reforming of steam exploded rice straw hydrolysate and condensate was explored heterogeneously for the first time over a 10 wt% WZ catalyst, resulting in excellent HMF yields as high as 15% under mild reaction conditions.

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

    Science.gov (United States)

    Munch, Federico D.; Zyserman, Fabio I.

    2016-07-01

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

  20. Effects of gamma radiation on phase behaviour and critical micelle concentration of Triton X-100 aqueous solutions

    International Nuclear Information System (INIS)

    Ionising radiation used for sterilisation can have an effect on the physico-chemical properties of pharmaceutically relevant excipient systems, affecting therefore the stability of the formulation. The effect of gamma irradiation on the phase behaviour (cloud point - CP) and critical micelle concentration (CMC) of aqueous solutions of Triton X-100, used as a model nonionic surfactant, is investigated in this paper. Micellar solutions irradiated with ?-rays in a dose range between 0 and 70 kGy, including the sterilisation range of pharmaceutical preparations, were analysed using mass spectrometry. Results show a slight shift in molecular mass distribution of ethoxylated surfactant, which indicates degradation of polyethoxylated chains by water radical attacks. This fact, combined with the formation of cross-linked species, is considered to be responsible for the decrease observed in CP and CMC values of micellar solutions at all absorbed doses. There is no spectroscopic evidence of radiation damage to aromatic ring or hydrocarbon tail of surfactant. Models based on Flory-Huggins theory were employed to estimate CP from changes in mass distribution and to obtain cross-linking fractions. (Author)

  1. Partitioning of L-methionine in aqueous two-phase systems containing poly(propylene glycol) and sodium phosphate salts

    Energy Technology Data Exchange (ETDEWEB)

    Salabat, Alireza, E-mail: a-salabat@araku.ac.ir [Chemistry Department, Arak University, P.O. Box 38156-879, Arak (Iran, Islamic Republic of); Sadeghi, Rahmat [Department of Chemistry, University of Kurdistan, Sanandaj, Kurdistan 66135 (Iran, Islamic Republic of); Moghadam, Somayeh Tiani [Chemistry Department, Arak University, P.O. Box 38156-879, Arak (Iran, Islamic Republic of); Jamehbozorg, Bahman [Department of Chemistry, University of Kurdistan, Sanandaj, Kurdistan 66135 (Iran, Islamic Republic of)

    2011-10-15

    Highlights: > Thermodynamics parameters for partitioning of L-methionine in ATPS. > Investigation of different effects on partition coefficient of the amino acid. > Propose the best condition for L-methionine partitioning. - Abstract: The partitioning behavior of L-methionine has been studied in aqueous two-phase systems of (poly(propylene glycol) + sodium phosphate salts + H{sub 2}O) at different temperatures. The salts used were sodium di-hydrogen phosphate (NaH{sub 2}PO{sub 4}), di-sodium hydrogen phosphate (Na{sub 2}HPO{sub 4}) and tri-sodium phosphate (Na{sub 3}PO{sub 4}). The effects of tie line length, salt type, and temperature on the partition coefficient of this amino acid have been studied. In addition, thermodynamic parameters ({Delta}H{sup o}, {Delta}S{sup o} and {Delta}G{sup o}) as a function of temperature were calculated. The results showed that increasing tie line length led to decreasing of the partition coefficient. We also showed that the partition coefficients of the amino acid in the systems containing Na{sub 3}PO{sub 4} are greater than the other two salts. Moreover, it is verified that increasing temperature led to decreasing the partition coefficient. The experimental partition coefficient data are correlated using a modified virial-type model.

  2. Catalytic Activity and Physical Properties of Various Metal Nanoparticles Supported on Bentonite in Aqueous Phase Hydrogenolysis of Glycerol

    International Nuclear Information System (INIS)

    The catalytic conversion of glycerol to 1,2-propanediol by aqueous phase hydrogenolysis on several noble metal catalysts was studied. Catalysts prepared from a variety of noble metal (Os, Ru, Pd and Au) supported on bentonite using conventional impregnation method showed different activity and selectivity. Among these catalysts, Os/ bentonite and Ru/ bentonite catalyst showed high activity in glycerol hydrogenolysis reaction at 150 degree Celsius, 20-30 hydrogen pressure for 7 hours. Analysis using TEM revealed that Os and Ru have smaller average size in range 1- 3 nm gave high activity which are 54.1 % and 61.2 % respectively. In contrast, less activity was obtained when using Pd/bentonite (29.0 %) and Au/bentonite (27.8 %) catalyst and TEM result showed that Pd and Au nanoparticles have large average particles size (8- 10) nm. This study revealed that size of nanoparticles metal catalyst play an important role in the performance and selectivity of the catalyst. These catalysts were also characterized by BET, XRD and XPS in order to get some physicochemical properties of the catalyst. (author)

  3. Development of green betaine-based deep eutectic solvent aqueous two-phase system for the extraction of protein.

    Science.gov (United States)

    Li, Na; Wang, Yuzhi; Xu, Kaijia; Huang, Yanhua; Wen, Qian; Ding, Xueqin

    2016-05-15

    Six kinds of new type of green betaine-based deep eutectic solvents (DESs) have been synthesized. Deep eutectic solvent aqueous two-phase systems (DES-ATPS) were established and successfully applied in the extraction of protein. Betaine-urea (Be-U) was selected as the suitable extractant. Single factor experiments were carried out to determine the optimum conditions of the extraction process, such as the salt concentration, the mass of DES, the separation time, the amount of protein, the temperature and the pH value. The extraction efficiency could achieve to 99.82% under the optimum conditions. Mixed sample and practical sample analysis were discussed. The back extraction experiment was implemented and the back extraction efficiency could reach to 32.66%. The precision experiment, repeatability experiment and stability experiment were investigated. UV-vis, FT-IR and circular dichroism (CD) spectra confirmed that the conformation of protein was not changed during the process of extraction. The mechanisms of extraction were researched by dynamic light scattering (DLS), the measurement of the conductivity and transmission electron microscopy (TEM). DES-protein aggregates and embraces phenomenon play considerable roles in the separation process. All of these results indicated that betaine-based DES-ATPS may provide a potential substitute new method for the separation of proteins. PMID:26992491

  4. Phase Behavior of Aqueous NA-K-MG-CA-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

    Energy Technology Data Exchange (ETDEWEB)

    M.S. Gruszkiewiez; D.A. Palmer; R.D. Springer; P. Wang; A. Anderko

    2006-09-14

    A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems.

  5. Analytical Round Robin for Elastic-Plastic Analysis of Surface Cracked Plates: Phase I Results

    Science.gov (United States)

    Wells, D. N.; Allen, P. A.

    2012-01-01

    An analytical round robin for the elastic-plastic analysis of surface cracks in flat plates was conducted with 15 participants. Experimental results from a surface crack tension test in 2219-T8 aluminum plate provided the basis for the inter-laboratory study (ILS). The study proceeded in a blind fashion given that the analysis methodology was not specified to the participants, and key experimental results were withheld. This approach allowed the ILS to serve as a current measure of the state of the art for elastic-plastic fracture mechanics analysis. The analytical results and the associated methodologies were collected for comparison, and sources of variability were studied and isolated. The results of the study revealed that the J-integral analysis methodology using the domain integral method is robust, providing reliable J-integral values without being overly sensitive to modeling details. General modeling choices such as analysis code, model size (mesh density), crack tip meshing, or boundary conditions, were not found to be sources of significant variability. For analyses controlled only by far-field boundary conditions, the greatest source of variability in the J-integral assessment is introduced through the constitutive model. This variability can be substantially reduced by using crack mouth opening displacements to anchor the assessment. Conclusions provide recommendations for analysis standardization.

  6. Mg2+-Dependent Control of the Spatial Arrangement of Rhodococcus erythropolis PR4 Cells in Aqueous-Alkane Two Phase Culture Containing n-Dodecane

    Science.gov (United States)

    Takihara, Hayato; Akase, Yumiko; Sunairi, Michio; Iwabuchi, Noriyuki

    2016-01-01

    We recently reported that a close relationship exists between alkane carbon-chain length, cell growth, and translocation frequency in Rhodococcus. In the present study, we examined the regulation of the spatial arrangement of cells in aqueous-alkane two phase cultures. An analysis of the effects of minerals on cell localization revealed that changes in the concentration of MgSO4 in two phase cultures containing n-dodecane (C12) altered cell localization from translocation to adhesion and vice versa. Our results indicate that the spatial arrangement of cells in two phase culture systems is controlled through the regulation of MgSO4 concentrations. PMID:27180641

  7. Analytical model of chemical phase and formation of DSB in chromosomes by ionizing radiation

    Czech Academy of Sciences Publication Activity Database

    Barilla, J.; Lokajíček, Miloš; Pisaková, Hana; Šimr, P.

    2013-01-01

    Roč. 36, č. 1 (2013), s. 11-17. ISSN 0158-9938 Institutional support: RVO:68378271 Keywords : radiobiological mechanism * chemical phase * DSB formation * oxygen effect Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 0.848, year: 2013

  8. Polymers as reference partitioning phase: polymer calibration for an analytically operational approach to quantify multimedia phase partitioning

    DEFF Research Database (Denmark)

    Gilbert, Dorothea; Witt, Gesine; Smedes, Foppe;

    2016-01-01

    ), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs) by equilibrating 13 silicones, including polydimethylsiloxane (PDMS) and low-density polyethylene (LDPE) in methanol-water solutions. Methanol as cosolvent ensured that all polymers reached equilibrium while its effect on the...... polymers' properties did not significantly affect silicone-silicone partition coefficients. However, we noticed minor cosolvent effects on determined polymer-polymer partition coefficients. Polymer-polymer partition coefficients near unity confirmed identical absorption capacities of several PDMS materials......-lipid, PDMS-air) and multimedia partition coefficients (lipid-water, air-water) were calculated by applying the new concept of a polymer as reference partitioning phase and by using polymer-polymer partition coefficients as conversion factors. The present study encourages the use of polymer-polymer partition...

  9. A static analytical apparatus for vapour pressures and (vapour + liquid) phase equilibrium measurements with an internal stirrer and view windows

    International Nuclear Information System (INIS)

    Highlights: • A new static analytical apparatus for vapour pressures and VLE data was designed. • The {R600a + R245fa} system was selected as a verification system. • Correlation of VLE data was made using PRvdWs and PRHVNRTL model. • Good agreement can be found with the literature data. - Abstract: A new static analytical apparatus for reliable vapour pressures and (vapour + liquid) equilibrium data of small-scale cell (≈150 mL) with internal stirrer and view windows was designed. In this work, the compositions of the phases were analyzed by a gas chromatograph connected on-line with TCD detectors. The operating pressure ranges from (0 to 3000) kPa, and the operating temperature range from (293 to 400) K. Phase equilibrium data for previously reported systems were first measured to test the credibility of the newly developed apparatus. The test included vapour pressure of 1,1,1,3,3-pentafluoropropane (R245fa) and isobutane (R600a), VLE of the (R600a + R245fa) system from T = (293.150 to 343.880) K. The measured VLE data are regressed with thermodynamic models using Peng–Robinson EoS with two different models, viz. the van der Waals mixing rule, and the Huron–Vidal mixing rule utilising the non-random two-liquid activity coefficient model. Thermodynamic consistency testing is also performed for the newly measured experimental data

  10. Analytical design of sensors for measuring during terminal phase of atmospheric temperature planetary entry

    Science.gov (United States)

    Millard, J. P.; Green, M. J.; Sommer, S. C.

    1972-01-01

    An analytical study was conducted to develop a sensor for measuring the temperature of a planetary atmosphere from an entry vehicle traveling at supersonic speeds and having a detached shock. Such a sensor has been used in the Planetary Atmosphere Experiments Test Probe (PAET) mission and is planned for the Viking-Mars mission. The study specifically considered butt-welded thermocouple sensors stretched between two support posts; however, the factors considered are sufficiently general to apply to other sensors as well. This study included: (1) an investigation of the relation between sensor-measured temperature and free-stream conditions; (2) an evaluation of the effects of extraneous sources of heat; (3) the development of a computer program for evaluating sensor response during entry; and (4) a parametric study of sensor design characteristics.

  11. Analytical calculation of the transition to complete phase synchronization in coupled oscillators

    Indian Academy of Sciences (India)

    P Muruganandam; F F Ferreira; H F El-Nashar; H A Cerdeira

    2008-06-01

    Here we present a system of coupled phase oscillators with nearest neighbors coupling, which we study for different boundary conditions. We concentrate at the transition to the total synchronization. We are able to develop exact solutions for the value of the coupling parameter when the system becomes completely synchronized, for the case of periodic boundary conditions as well as for a chain with fixed ends. We compare the results with those calculated numerically.

  12. Development of analytical methodologies for iodine species in gaseous and particulate phases of the coastal atmosphere

    OpenAIRE

    Chen, Hongwei

    2005-01-01

    It has been demonstrated that iodine does have an important influence on atmospheric chemistry, especially the formation of new particles and the enrichment of iodine in marine aerosols. It was pointed out that the most probable chemical species involved in the production or growth of these particles are iodine oxides, produced photochemically from biogenic halocarbon emissions and/or iodine emission from the sea surface. However, the iodine chemistry from gaseous to particulate phase in the ...

  13. Phase equilibria of methane and carbon dioxide clathrate hydrates in the presence of (methanol + MgCl2) and (ethylene glycol + MgCl2) aqueous solutions

    International Nuclear Information System (INIS)

    Highlights: • Hydrate dissociation conditions for CH4 and CO2 in the presence of pure water/inhibitor aqueous solution are reported. • The inhibitors include: methanol + MgCl2 and ethylene glycol + MgCl2. • An isochoric pressure-search method was used in all the experimental data measurements. • The aqueous solutions shift the equilibrium data to high pressure/low temperature. • The aqueous solutions containing methanol has more inhibition effect than ethylene glycol. -- Abstract: In this work, the experimental data for the equilibrium conditions of methane and carbon dioxide clathrate hydrates in the presence of (0.1 mass fraction methanol + 0.03, 0.1 mass fraction MgCl2) and (0.1, 0.2 mass fraction ethylene glycol + 0.1 mass fraction MgCl2) aqueous solutions at different temperature and pressure range 263.74 to 280.54 K and 0.98 to 8.02 MPa, respectively and for various concentrations of inhibitors are reported, which is not available in open literature. The equilibrium pressure–temperature curves were generated using an isochoric pressure-search method. The experimental results of methane and carbon dioxide clathrate hydrates in the presence of pure water and the above mentioned aqueous inhibitor solutions are compared with some selected experimental data from the literature in the presence of pure water, single glycol, alcohol or salt aqueous solutions to validate the experimental result and to show the inhibition effects of the aqueous solutions used in this work. The results show that the phase equilibrium of the quaternary system (H2O + ethylene glycol/methanol + CH4/CO2 + MgCl2) is shifted to higher pressures/lower temperatures compared to the phase equilibrium of pure CH4/CO2 due to the inhibition effect. Also, it has been observed that the quaternary system containing methanol has a more inhibition effect than the quaternary system containing ethylene glycol at the same mass fraction of the inhibitor in the aqueous solution

  14. Design and development of single stage purification of papain using Ionic Liquid based aqueous two phase extraction system and its Partition coefficient studies

    Directory of Open Access Journals (Sweden)

    Senthilkumar Rathnasamy

    2013-04-01

    Full Text Available As an emerging trend in bioseparation, aqueous two phase extractions based on phosponium ionic liquid have been utilized in this work to extract papain from Carica papaya fruit latex and the same wascompared with conventional aqueous two phase extraction system. Factors affecting the partition coefficient of papain such as ionic liquid concentration, pH of the extraction system and temperature have been investigated. The optimization studies show that ionic liquid concentrations and pH are majorly influencing the phaseformations and papain partitioning. It reveals the importance of electrostatic and hydrophobic interactions in the papain partitioning. Purification studies performed on Gel Filtration Chromatography shows that 96% of the papain enzyme could be extracted with the phosponium based ionic liquid in a single stage extraction. The final fraction containing papain enzyme was confirmed by SDS Page analysis.

  15. A plant-wide aqueous phase chemistry module describing pH variations and ion speciation/pairing in wastewater treatment process models

    DEFF Research Database (Denmark)

    Flores Alsina, Xavier; Kazadi Mbamba, Christian; Solon, Kimberly;

    2015-01-01

    There is a growing interest within the Wastewater Treatment Plant (WWTP) modelling community to correctly describe physico-chemical processes after many years of mainly focusing on biokinetics. Indeed, future modelling needs, such as a plant-wide phosphorus (P) description, require a major, but...... unavoidable, additional degree of complexity when representing cationic/anionic behaviour in Activated Sludge (AS)/Anaerobic Digestion (AD) systems. In this paper, a plant-wide aqueous phase chemistry module describing pH variations plus ion speciation/pairing is presented and interfaced with industry...... different cationic/anionic loads. In this way, the general applicability/flexibility of the proposed approach is demonstrated, by implementing the aqueous phase chemistry module in some of the most frequently used WWTP process simulation models. Finally, it is shown how traditional wastewater modelling...

  16. Simultaneous separation/enrichment and detection of trace ciprofloxacin and lomefloxacin in food samples using thermosensitive smart polymers aqueous two-phase flotation system combined with HPLC.

    Science.gov (United States)

    Lu, Yang; Chen, Bo; Yu, Miao; Han, Juan; Wang, Yun; Tan, Zhenjiang; Yan, Yongsheng

    2016-11-01

    Smart polymer aqueous two phase flotation system (SPATPF) is a new separation and enrichment technology that integrated the advantages of the three technologies, i.e., aqueous two phase system, smart polymer and flotation sublation. Ethylene oxide and propylene oxide copolymer (EOPO)-(NH4)2SO4 SPATPF is a pretreatment technique, and it is coupled with high-performance liquid chromatography to analyze the trace ciprofloxacin and lomefloxacin in real food samples. The optimized conditions of experiment were determined in the multi-factor experiment by using response surface methodology. The flotation efficiency of lomefloxacin and ciprofloxacin was 94.50% and 98.23% under the optimized conditions. The recycling experimentsshowed that the smart polymer EOPO could use repeatedly, which will reduce the cost in the future application. PMID:27211613

  17. Behaviour of water during temperature-induced phase transition in poly(vinyl methyl ether) aqueous solutions. NMR and optical microscopy study

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Hanyková, L.; Labuta, J.

    Istanbul : Department of Chemical Engineering, Yeditepe University, 2009. P.IV.033. [European Colloid and Interface Society Meeting /23./. 06.09.2009-11.09.2009, Antalya ] R&D Projects: GA ČR GA202/09/1281 Institutional research plan: CEZ:AV0Z40500505 Keywords : temperature-induced phase transition * hydration * poly(vinyl methyl ether) aqueous solution * NMR Subject RIV: CD - Macromolecular Chemistry

  18. Aqueous-phase reforming of xylitol over Pt/C and Pt/TiC-CDC catalysts : catalyst characterization and catalytic performance

    OpenAIRE

    Kirilin, Alexey V.; Hasse, Benjamin; Tokarev, Anton V.; Kustov, Leonid M.; Baeva, Galina N.; Bragina, Galina O.; Stakheev, Aleksandr Yu.; Rautio, Anne-Riikka; Salmi, Tapio; Etzold, Bastian J.M.; Mikkola, Jyri-Pekka; Murzin, Dmitry Yu

    2014-01-01

    The aqueous phase reforming (APR) of xylitol was studied over five Pt/C catalysts. The correlation between physico-chemical properties of the catalysts and catalytic performance was established. The Pt/C catalysts have different textural properties as well as different mean Pt cluster sizes and surface acidity. The average Pt cluster size was investigated by means of CO chemisorption as well as by TEM. The reaction was found to be structure sensitive and TOF linearly increases with increasing...

  19. Partitioning and purification of extracellular β-1,3-1,4-glucanase in aqueous two-phase systems

    Institute of Scientific and Technical Information of China (English)

    HE Guo-qing; ZHANG Xiu-yan; TANG Xing-jun; CHEN Qi-he; RUAN Hui

    2005-01-01

    The partition behaviors of β-1,3-1,4-glucanase, α-amylase and neutral proteases from clarified and whole fermentation broths of Bacillus subtilis ZJF-1A5 were investigated. An aqueous two-phase system (polyethylene glycol (PEG)/MgSO4)was examined with regard to the effects of PEG molecular weight (MW) and concentration, MgSO4 concentration, pH and NaCl concentration on enzyme partition and extraction. The MW and concentration of PEG were found to have significant effects on enzyme partition and extraction with low MW PEG showing the greatest benefit in the partition and extraction of β-glucanase with the PEG/MgSO4 system. MgSO4 concentration influenced the partition and extraction of β-glucanase significantly. pH had little effect on β-glucanase or proteases partition but affected α-amylase partition when pH was over 7.0. The addition of NaCl had little effect on the partition behavior of β-glucanase but had very significant effects on the partitioning of α-amylase and on the neutral proteases. The partition behaviors of β-glucanase, α-amylase and proteases in whole broth were also investigated and results were similar to those obtained with clarified fermentation broth. A two-step process for purifying β-glucanase was developed, which achieved β-glucanase recovery of 65.3% and specific activity of 14027 U/mg, 6.6 times improvement over the whole broth.

  20. Using radon as environmental tracer for the assessment of subsurface non-aqueous phase liquid (NAPL) contamination - a review

    International Nuclear Information System (INIS)

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

  1. Analytical method for softness abrasive flow field based on discrete phase model

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Aiming at the problem of difficult contact finishing for mini structural surface in course of mould manufacturing,a new no-tool precision machining method based on soft abrasive flow machining (SAFM) was proposed. It allocated restrained component near surface machined,constituted restrained abrasive flow passage,and made the surface become a segment of passage wall. It could control turbulence abrasive flow in restrained passage,realize micro cutting for passage wall,and utilize the irregular motion of abrasive flow to eliminate the mono-directional marks on machined surfaces,and the precision could reach the specular level. A two-phase dynamic model of abrasive flow oriented to SAFM combined with discrete phase model (DPM) was established,the law of two-phase flow motion and the related physical parameters was obtained by corresponding numerical simulation method,and the mechanism of precision machining in SAFM was discussed. Simulation results show that the abrasive flow machining process mainly appears as translation of ablating location with the influence by granular pressure,and as the variation of machining efficiency with the influence by near-wall particle velocity. Thus via control of the inlet velocity and its corresponding machining time,it is supposed to work out the machining process according to the machining requirements by using the Preston equation to seek the relationship among velocity,pressure and material removing rate. By tracking near-wall particles,it can be confirmed that the movement of near-wall abrasive particles is similar to stream-wise vortices. The cutting traces on workpiece surfaces assume disorderly arrangement,so the feasibility of the SAFM method can be reaffirmed.

  2. Analytical data from phases I and II of the Willamette River basin water quality study, Oregon

    Science.gov (United States)

    Harrison, Howard E.; Anderson, Chauncey W.; Rinella, Frank A.; Gasser, Timothy M.; Pogue, Ted R., Jr.

    1995-01-01

    This report presents trace-element, organic-compound (pesticides, volatile and semivolatile organic compounds, and dioxin and furan compounds), and nutrient concentration data from the analyses of water column, suspended-sediment, and bed-sediment samples collected by the U.S. Geological Survey as part of Phases I and II of the comprehensive Willamette River Basin Water Quality Study in western Oregon. The overall study was designed by the Oregon Department of Environmental Quality to acquire the technical and regulatory knowledge necessary to protect and enhance water quality in the Willamette River Basin.

  3. Quantum chemical analysis of the energy of proton transfer from phenol and chlorophenols to H2O in the gas phase and in aqueous solution

    Science.gov (United States)

    Schüürmann, Gerrit

    1998-12-01

    Proton transfer energies of phenol and 14 chlorophenols with H2O as a base are analyzed in the gas phase and in solution using quantum chemical methods at the semiempirical and ab initio level of computation. The effect of aqueous solution was accounted for by applying the density functional theory (DFT) implementation of the conductor-like screening model (COSMO) as well as semiempirical continuum-solvation models. The results reveal substantial and systematic overestimations of the free energies of proton transfer as derived from experimental solution-phase pKa data. This can be traced back to both deficiencies in the current model parameterization as well as to limitations of the underlying gas-phase quantum chemical models, which is further illustrated by additional complete-basis-set (CBS) calculations for the proton transfer reaction with phenol. In contrast, the relative pKa trend is reflected well by COSMO-DFT calculations with correlation coefficients (adjusted for degrees of freedom) of 0.96. Decomposition of the dissociation energy in aqueous solution into a gas-phase term and a term summarizing the solvation contributions provides new insights into the effect of solvation on proton transfer energies, and yields mechanistic explanations for the observed differences in the gas-phase and solution-phase acidity orders of various subgroups of the compounds.

  4. Reversible hydration and aqueous exfoliation of the acetate-intercalated layered double hydroxide of Ni and Al: Observation of an ordered interstratified phase

    Energy Technology Data Exchange (ETDEWEB)

    Manohara, G.V. [Department of Chemistry, The Central College Campus, Bangalore University, Bangalore 560 001 (India); Vishnu Kamath, P., E-mail: vishnukamath8@hotmail.com [Department of Chemistry, The Central College Campus, Bangalore University, Bangalore 560 001 (India); Milius, Wolfgang [Department of Inorganic Chemistry I, University of Bayreuth, Bayreuth D-95440 (Germany)

    2012-12-15

    Acetate-intercalated layered double hydroxides (LDHs) of Ni and Al undergo reversible hydration in the solid state in response to the ambient humidity. The LDH with a high layer charge (0.33/formula unit) undergoes facile hydration in a single step, whereas the LDH with a lower layer charge (0.24/formula unit) exhibits an ordered interstratified intermediate, comprising the hydrated and dehydrated layers stacked alternatively. This phase, also known as the staged S-2 phase, coexists with the end members suggesting the existence of a solution-type equilibrium between the S-2 phase and the end members of the hydration cycle. These LDHs also undergo facile aqueous exfoliation into 2-5 nm-thick tactoids with a radial dimension of 0.2-0.5 {mu}m. - Graphical abstract: Schematic of the hydrated, dehydrated and interstratified phases observed during the hydration-dehydration of Ni/Al-CH{sub 3}COO LDH. Highlights: Black-Right-Pointing-Pointer Ni/Al-acetate LDHs were synthesized by HPFS method by hydrolysis of acetamide. Black-Right-Pointing-Pointer Intercalated acetate ion shows reversible hydration with variation in humidity. Black-Right-Pointing-Pointer An ordered interstratified phase was observed during hydration/dehydration cycle. Black-Right-Pointing-Pointer A solution type equilibrium is observed between hydration-dehydration phases. Black-Right-Pointing-Pointer These LDHs undergo facile aqueous exfoliation.

  5. Reversible hydration and aqueous exfoliation of the acetate-intercalated layered double hydroxide of Ni and Al: Observation of an ordered interstratified phase

    International Nuclear Information System (INIS)

    Acetate-intercalated layered double hydroxides (LDHs) of Ni and Al undergo reversible hydration in the solid state in response to the ambient humidity. The LDH with a high layer charge (0.33/formula unit) undergoes facile hydration in a single step, whereas the LDH with a lower layer charge (0.24/formula unit) exhibits an ordered interstratified intermediate, comprising the hydrated and dehydrated layers stacked alternatively. This phase, also known as the staged S-2 phase, coexists with the end members suggesting the existence of a solution-type equilibrium between the S-2 phase and the end members of the hydration cycle. These LDHs also undergo facile aqueous exfoliation into 2–5 nm-thick tactoids with a radial dimension of 0.2–0.5 μm. - Graphical abstract: Schematic of the hydrated, dehydrated and interstratified phases observed during the hydration–dehydration of Ni/Al–CH3COO LDH. Highlights: ► Ni/Al-acetate LDHs were synthesized by HPFS method by hydrolysis of acetamide. ► Intercalated acetate ion shows reversible hydration with variation in humidity. ► An ordered interstratified phase was observed during hydration/dehydration cycle. ► A solution type equilibrium is observed between hydration–dehydration phases. ► These LDHs undergo facile aqueous exfoliation.

  6. Test plan for Geo-Cleanse reg-sign demonstration (in situ destruction of dense non-aqueous phase liquid (DNAPL))

    International Nuclear Information System (INIS)

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

  7. Study of the applicability of non-conventional aqueous two-phase systems in counter-current and centrifugal partition chromatography.

    Science.gov (United States)

    Bezold, Franziska; Goll, Johannes; Minceva, Mirjana

    2015-04-01

    Aqueous two-phase systems composed of imidazolium-based ionic liquids and phosphate salts were evaluated for their applicability in liquid-liquid chromatography. The influence of the nature of ionic liquid anion and cation on the partitioning of bovine serum albumin, lysozyme and myoglobin was investigated. A mixture of K2HPO4 and KH2PO4 in a ratio of 1.82:1 wt/wt was used in all of the tested biphasic systems to adjust the pH to a range of 7-8. The results show that more hydrophobic cations decrease the partition coefficients of the proteins in the biphasic systems and outweigh the effect of the anion on the distribution of the macromolecules. Viscosities and densities of the biphasic systems were in a suitable range for liquid-liquid chromatography. Even though the partition coefficients were too high for a conventional batch operation mode, these aqueous two-phase systems show favorable properties for protein capturing in liquid-liquid chromatographic columns. Additionally, the possible application of ionic liquids as modifiers in polyethylene glycol (PEG)-based aqueous two-phase systems was investigated. It could be demonstrated that ionic liquids alter the partition coefficients of the proteins. PMID:25736304

  8. Phase equilibrium measurements for semi-clathrate hydrates of the (CO2 + N2 + tetra-n-butylammonium bromide) aqueous solution system

    International Nuclear Information System (INIS)

    Highlights: ► Semi-clathrate hydrate phase equilibrium for CO2+N2+TBAB aqueous solutions. ► Measurements for temperatures from 277.1 K to 293.2 K and pressures up to 16.21 MPa. ► TBAB has a promotion effect on semi-clathrate hydrate formation. - Abstract: The application of semi-clathrate hydrate formation technology for gas separation purposes has gained much attention in recent years. Consequently, there is a demand for experimental data for relevant semi-clathrate hydrate phase equilibria. In this work, semi-clathrate hydrate dissociation conditions for the system comprising mixtures of {CO2 (0.151/0.399 mole fraction) + N2 (0.849/0.601 mole fraction) + 0.05, 0.15, and 0.30 mass fraction tetra-n-butylammonium bromide (TBAB)} aqueous solutions have been measured and are reported. An experimental apparatus which was designed and built in-house was used for the measurements using the isochoric pressure-search method. The range of conditions for the measurements was from 277.1 K to 293.2 K for temperature and pressures up to 16.21 MPa. The phase equilibrium data measured demonstrate the high hydrate promotion effects of TBAB aqueous solutions.

  9. Analytical modeling of instabilities of two-phase flows in BWR boiling channels

    International Nuclear Information System (INIS)

    New approaches are presented in studying the mechanism of the coupled thermal/nuclear instabilities in BWR's. For the case of instabilities of the in-phase mode, a simple model based on the point-reactor model for the neutron dynamics and the lumped parameter model for the fuel dynamics was found useful in revealing the basic mechanism. For the case of instabilities of the out-of-phase mode, new models are developed which, in different levels of sophistication, take into consideration the nuclear/thermal interaction between different parts of a BWR core. In a simpler model called the subcore model, a coefficient is introduced which allows the neutron density in one subcore to be affected by the reactivity in another subcore. In a more completed model called the multi-point reactor model, a similar coefficient is introduced in establishing the neutron dynamics equation for each subcore, which directly accounts for the effect of neutron diffusion between subcores. Results are presented for these models, and discussions are made on their usefulness. (author)

  10. Liquid-liquid transfer phenomena studies coupled with redox reactions: back-extraction of nitrous acid in the presence of scavengers in aqueous phase

    International Nuclear Information System (INIS)

    This work deals with the investigation of redox reaction contribution to the kinetics of liquid-liquid transfer, in relation with PUREX reprocessing of spent nuclear fuel. The chemical system chosen concerns the tripping of nitrous acid from tributylphosphate organic phase into a nitric acid aqueous solution containing an 'anti-nitrous' component, namely hydrazinium nitrate. According to the abundant literature, a major attention is devoted to the very important role of interfacial phenomena on the kinetics of solvent extraction with tributylphosphate. Although, a suitable experimental technique is chosen, using a constant interfacial area cell of the ARMOLLEX-type. Furthermore, the effects of the hydrodynamical and the physico-chemical parameters on the extraction rate led to the identification of the extraction regime nature: diffusional, then chemical limitation. When no 'anti-nitrous' component is used, the diffusional resistance is found to be mainly located in the aqueous diffusion layer. The presence of hydrazinium nitrate into the aqueous solution has an overall accelerating effect on the rate of extraction, related to both a complete suppression of the aqueous diffusional resistance, and a very significant enhancement of the interfacial transfer of the nitrous acid, as a function of hydrazinium concentration. If the first effect could be expected because of the well known fast redox reaction in aqueous phase, the second phenomenon represents a quite original and new result which has never been explored before, to the best of our knowledge. A reaction mechanism is postulated and validated, taking into account the reactive effect of hydrazinium on the interfacial step. In order to support the drawn general patterns, different complementary studies were attempted. When hydroxyl-ammonium nitrate is used, a surprising interfacial transfer blockage is observed, pointing out the extreme performance and specificity of the common hydrazinium component. (author)

  11. Ordered mesoporous carbon film as an effective solid-phase microextraction coating for determination of benzene series from aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Hui [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); School of Geography Science, Nantong University, Nantong 226001 (China); Li, Jiansheng, E-mail: lijsh@mail.njust.edu.cn [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Jiang, Mingyue; Lu, Rui; Shen, Jinyou; Sun, Xiuyun; Han, Weiqing [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Wang, Lianjun, E-mail: wanglj@mail.njust.edu.cn [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2015-08-12

    The present work reports preparation of ordered mesoporous carbon (OMC) film supported on a graphite fiber as a new type of solid-phase microextraction (SPME) fiber for determination of benzene series from aqueous media. The strategy for the supported OMC film preparation was combined dip-coating technology with solvent evaporation-induced self-assembly (EISA) approach. A graphite fiber was immersed in an ethanol solution containing phenolic resin and Pluronic triblock copolymer. Upon solvent evaporation and subsequent pyrolysis under 700 °C, the phenolic resin and the surfactant self-assembled on the surface of the graphite fiber to form smooth OMC film. X-ray diffraction (XRD), transmission electron microscopy (TEM) and nitrogen isothermal adsorption results indicate that the resultant OMC film possesses well-ordered two dimensional hexagonal mesostructure with pore diameters of 4.5 nm and BET surfaces of 630 m{sup 2}/g. Scanning electron microscopy (SEM) studies show the supported OMC film with thickness at 8.5 μm is continuous and defect-free. The SPME efficiency of the OMC fiber was evaluated by analysis of five benzene series (benzene, toluene, ethylbenzene, p-xylene and m-xylene) from water samples by gas chromatography-flame ionization detection (GC-FID). The analysis results indicate that the prepared OMC fiber has wide linear ranges (0.5–500 μg/L), low detection limits (0.01–0.05 μg/L) and good repeatabilities (4.0–5.8% for one fiber, 2.9–8.7% for fiber-to-fiber). Compared with commercial counterparts, the OMC fiber exhibits improved extraction efficiency for benzene series and PAHs. - Highlights: • Ordered mesoporous carbon film supported on graphite fiber was first reported as solid-phase microextraction coating. • The strategy for the film preparation was combined dip-coating technology with evaporation-induced self-assembly approach. • The obtained fiber showed enhanced thermal stability and organic solvents resistance. • The

  12. Purification of a fibrinolytic protease from Mucor subtilissimus UCP 1262 by aqueous two-phase systems (PEG/sulfate).

    Science.gov (United States)

    Nascimento, Thiago Pajeú; Sales, Amanda Emmanuelle; Porto, Camila Souza; Brandão, Romero Marcos Pedrosa; de Campos-Takaki, Galba Maria; Teixeira, José Antônio Couto; Porto, Tatiana Souza; Porto, Ana Lúcia Figueiredo; Converti, Attilio

    2016-07-01

    A fibrinolytic protease from M. subtilissimus UCP 1262 was recovered and partially purified by polyethylene glycol (PEG)/sodium sulfate aqueous two-phase systems (ATPS). The simultaneous influence of PEG molar mass, PEG concentration and sulfate concentration on the enzyme recovery was first investigated using a 2(3) full factorial design, and the Response Surface Methodology used to identify the optimum conditions for enzyme extraction by ATPS. Once the best PEG molar mass for the process had been selected (6000g/mol), a two-factor central composite rotary design was applied to better evaluate the effects of the other two independent variables. The fibrinolytic enzyme was shown to preferentially partition to the bottom phase with a partition coefficient (K) ranging from 0.2 to 0.7. The best results in terms of enzyme purification were obtained with the system formed by 30.0% (w/w) PEG 6000g/mol and 13.2% (w/w) sodium sulfate, which ensured a purification factor of 10.0, K of 0.2 and activity yield of 102.0%. SDS-PAGE and fibrin zymography showed that the purified protease has a molecular mass of 97kDa and an apparent isoelectric point of 5.4. When submitted to assays with different substrates and inhibitors, it showed selectivity for succinyl-l-ala-ala-pro-l-phenylalanine-p-nitroanilide and was almost completely inhibited by phenylmethylsulfonyl fluoride, behaving as a chymotrypsin-like protease. At the optimum temperature of 37°C, the enzyme residual activity was 94 and 68% of the initial one after 120 and 150min of incubation, respectively. This study demonstrated that M. subtilissimus protease has potent fibrinolytic activity compared with similar enzymes produced by solid-state fermentation, therefore it may be used as an agent for the prevention and therapy of thrombosis. Furthermore, it appears to have the advantages of low cost production and simple purification. PMID:27183214

  13. Ordered mesoporous carbon film as an effective solid-phase microextraction coating for determination of benzene series from aqueous media

    International Nuclear Information System (INIS)

    The present work reports preparation of ordered mesoporous carbon (OMC) film supported on a graphite fiber as a new type of solid-phase microextraction (SPME) fiber for determination of benzene series from aqueous media. The strategy for the supported OMC film preparation was combined dip-coating technology with solvent evaporation-induced self-assembly (EISA) approach. A graphite fiber was immersed in an ethanol solution containing phenolic resin and Pluronic triblock copolymer. Upon solvent evaporation and subsequent pyrolysis under 700 °C, the phenolic resin and the surfactant self-assembled on the surface of the graphite fiber to form smooth OMC film. X-ray diffraction (XRD), transmission electron microscopy (TEM) and nitrogen isothermal adsorption results indicate that the resultant OMC film possesses well-ordered two dimensional hexagonal mesostructure with pore diameters of 4.5 nm and BET surfaces of 630 m2/g. Scanning electron microscopy (SEM) studies show the supported OMC film with thickness at 8.5 μm is continuous and defect-free. The SPME efficiency of the OMC fiber was evaluated by analysis of five benzene series (benzene, toluene, ethylbenzene, p-xylene and m-xylene) from water samples by gas chromatography-flame ionization detection (GC-FID). The analysis results indicate that the prepared OMC fiber has wide linear ranges (0.5–500 μg/L), low detection limits (0.01–0.05 μg/L) and good repeatabilities (4.0–5.8% for one fiber, 2.9–8.7% for fiber-to-fiber). Compared with commercial counterparts, the OMC fiber exhibits improved extraction efficiency for benzene series and PAHs. - Highlights: • Ordered mesoporous carbon film supported on graphite fiber was first reported as solid-phase microextraction coating. • The strategy for the film preparation was combined dip-coating technology with evaporation-induced self-assembly approach. • The obtained fiber showed enhanced thermal stability and organic solvents resistance. • The fiber

  14. V6O13 films by control of the oxidation state from aqueous precursor to crystalline phase

    OpenAIRE

    PEYS, Nick; Ling, Yun; DEWULF, Daan; Gielis, Sven; DE DOBBELAERE, Christopher; Cuypers, Daniel; Adriaensens, Peter; Van Doorslaer, Sabine; De Gendt, Stefan; Hardy, An; Van Bael, Marlies

    2013-01-01

    An aqueous deposition process for V6O13 films is developed whereby the vanadium oxidation state is continuously controlled throughout the entire process. In the precursor stage, a controlled wet chemical reduction of the vanadium(V) source with oxalic acid is achieved and monitored by (51)Vanadium Nuclear Magnetic Resonance (V-51-NMR) and Ultraviolet-Visible (UV-Vis) spectroscopy. The resulting vanadium(IV) species in the aqueous solution are identified as mononuclear citrato-oxovanadate(IV) ...

  15. Analytical Phase Equilibrium Function for Mixtures Obeying Raoult's and Henry's Laws

    Science.gov (United States)

    Hayes, Robert

    When a mixture of two substances exists in both the liquid and gas phase at equilibrium, Raoults and Henry's laws (ideal solution and ideal dilute solution approximations) can be used to estimate the gas and liquid mole fractions at the extremes of either very little solute or solvent. By assuming that a cubic polynomial can reasonably approximate the intermediate values to these extremes as a function of mole fraction, the cubic polynomial is solved and presented. A closed form equation approximating the pressure dependence on mole fraction of the constituents is thereby obtained. As a first approximation, this is a very simple and potentially useful means to estimate gas and liquid mole fractions of equilibrium mixtures. Mixtures with an azeotrope require additional attention if this type of approach is to be utilized. This work supported in part by federal Grant NRC-HQ-84-14-G-0059.

  16. Liquid-liquid equilibrium and partitioning features of bovine trypsin in Ucon 50 HB5100 /sodium citrate aqueous two phase systems

    OpenAIRE

    Tubío, Gisela; Venâncio, Armando; J. A. Teixeira; Nerli, Bibiana B.; Picó, Guillermo A.

    2008-01-01

    The phase diagrams of Ucon 50-HB-5100, a non-ionic random copolymer of ethylene oxide and propylene oxide (EOPO) and sodium citrate aqueous two-phase systems were determined at different pHs (5.20 and 8.20) and temperatures (5, 20 and 40º C). The binodal curves were determined by refractive index and enzymatic assay of the solution and described using a four-parameter sigmoidal equation, the reliability of the measured tie line compositions was ascertained by correlation equations...

  17. Determination of methyl mercury by aqueous phase Eehylation, followed by gas chromatographic separation with cold vapor atomic fluorescence detection

    Science.gov (United States)

    De Wild, John F.; Olsen, Mark L.; Olund, Shane D.

    2002-01-01

    A recent national sampling of streams in the United States revealed low methyl mercury concentrations in surface waters. The resulting median and mean concentrations, calculated from 104 samples, were 0.06 nanograms per liter (ng/L) and 0.15 ng/L, respectively. This level of methyl mercury in surface water in the United States has created a need for analytical techniques capable of detecting sub-nanogram per liter concentrations. In an attempt to create a U.S. Geological Survey approved method, the Wisconsin District Mercury Laboratory has adapted a distillation/ethylation/ gas-phase separation method with cold vapor atomic fluorescence spectroscopy detection for the determination of methyl mercury in filtered and unfiltered waters. This method is described in this report. Based on multiple analyses of surface water and ground-water samples, a method detection limit of 0.04 ng/L was established. Precision and accuracy were evaluated for the method using both spiked and unspiked ground-water and surface-water samples. The percent relative standard deviations ranged from 10.2 to 15.6 for all analyses at all concentrations. Average recoveries obtained for the spiked matrices ranged from 88.8 to 117 percent. The precision and accuracy ranges are within the acceptable method-performance limits. Considering the demonstrated detection limit, precision, and accuracy, the method is an effective means to quantify methyl mercury in waters at or below environmentally relevant concentrations

  18. Sound propagation in dilute suspensions of spheres: Analytical comparison between coupled phase model and multiple scattering theory.

    Science.gov (United States)

    Valier-Brasier, Tony; Conoir, Jean-Marc; Coulouvrat, François; Thomas, Jean-Louis

    2015-10-01

    Sound propagation in dilute suspensions of small spheres is studied using two models: a hydrodynamic model based on the coupled phase equations and an acoustic model based on the ECAH (ECAH: Epstein-Carhart-Allegra-Hawley) multiple scattering theory. The aim is to compare both models through the study of three fundamental kinds of particles: rigid particles, elastic spheres, and viscous droplets. The hydrodynamic model is based on a Rayleigh-Plesset-like equation generalized to elastic spheres and viscous droplets. The hydrodynamic forces for elastic spheres are introduced by analogy with those of droplets. The ECAH theory is also modified in order to take into account the velocity of rigid particles. Analytical calculations performed for long wavelength, low dilution, and weak absorption in the ambient fluid show that both models are strictly equivalent for the three kinds of particles studied. The analytical calculations show that dilatational and translational mechanisms are modeled in the same way by both models. The effective parameters of dilute suspensions are also calculated. PMID:26520342

  19. Development of analytical methodology for determination of chloroform in samples of flavoured waters using headspace-solid phase microextraction technique

    Directory of Open Access Journals (Sweden)

    Marcel Silveira dos Santos

    2009-11-01

    Full Text Available A simple and fast analytical methodology was developed using the headspace-solid phase micro extration (HS-SPME for the determination of chloroform in 15 samples of flavoured waters. The extraction of the chloroform was performed with the fiber CAR-PDMS and analyzed on a gas chromatography equipped with electron capture detector (ECD - 63Ni. The variables that affect the efficiency of extraction: temperature and time of extraction, volume of headspace, magnetic stirring and salt addition were optimized. The linearity of the method ranged from 0,5 - 45 µg L-1. Low limit of detection was obtained, 0,46 µg L-1. The method showed excellent precision, calculated as the relative standard deviation (RSD% (n = 6 using spiked solutions of 1, 15 and 35 µg L-1 of chloroform, values obtained: 11,2%, 6,4% and 5,7%. Excellent relative sensitivity of 94% was obtained.

  20. Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 1: Concept development and feasibility

    Science.gov (United States)

    Oken, S.; June, R. R.

    1971-01-01

    The analytical and experimental investigations are described in the first phase of a program to establish the feasibility of reinforcing metal aircraft structures with advanced filamentary composites. The interactions resulting from combining the two types of materials into single assemblies as well as their ability to function structurally were studied. The combinations studied were boron-epoxy reinforced aluminum, boron-epoxy reinforced titanium, and boron-polyimide reinforced titanium. The concepts used unidirectional composites as reinforcement in the primary loading direction and metal for carrying the transverse loads as well as its portion of the primary load. The program established that several realistic concepts could be fabricated, that these concepts could perform to a level that would result in significant weight savings, and that there are means for predicting their capability within a reasonable degree of accuracy. This program also encountered problems related to the application of polyimide systems that resulted in their relatively poor and variable performance.

  1. Analyticity of Transverse Polarization Tensor in the Normal Phase of hot QED and Gauge/Gravity Duality

    CERN Document Server

    Yin, Lei; Lee, Ting Kou; Hou, Defu

    2016-01-01

    We explore the momentum analyticity of the static transverse polarization tensor of a 2+1 dimensional holographic superconductor in its normal phase with a nonzero chemical potential, aiming at finding the holographic counterpart of the singularities underlying the Friedel-like oscillations of an ordinary field theory. We prove that the polarization tensor is a meromorphic function with an infinite number of poles located on the complex momentum plane off real axis. With the aid of the WKB approximation these poles are found to lies asymptotically along two straight lines parallel to the imaginary axis for a large momentum magnitude. The similarity between the holographic Green's function and that of an weakly coupled ordinary field theory (e.g., 2+1 dimensional QED) regarding the location of the momentum singularities offers further support to the validity of the gauge/gravity duality.

  2. On the Impact of GPS phase centre corrections on geodetic parameters: analytical formulation and empirical evaluation by PPP

    Science.gov (United States)

    Hiemer, Leonard; Kersten, Tobias; Schön, Steffen

    2015-04-01

    Several contributions and papers in geodesy intensively discuss the impact of the variability of GPS/GNSS absolute phase centre corrections (PCCs) directly on the positioning domain, neglecting any studies on the observation domain. Furthermore, it is very complex to evaluate in a general way the impact of several PCCs in geodetic positioning due to the different positioning concepts (e.g. PPP, relative positioning in networks) as well as implementation philosophy. Up to know, it is not clear how accurate different PCCs have to be for an individual geodetic grade antenna, in order to assume no significant and negative impact on the geodetic parameter estimation. Currently, individual calibrations have to be comparable of at least below 1mm. The poster will cover this topic by studying the observation domain as well as the geodetic position domain. The used approach is based on a pragmatic method, investigated by Geiger (1988), using generic PCC pattern. The contribution is divided into an analytical approach and an empirical approach. The analytical step discusses in detail the mathematical model and the propagation of error functions, classified by several antenna models. The empirical step evaluates these findings by practical experiments carried out with pre-defined errors on PCCs within a geodetic positioning estimation (PPP) using different software packages. We will show on the one side that some symmetrical error contributions of typical geodetic antenna designs can be described very well by this simple and pragmatic approach. The theoretical findings are compared to PPP solutions, revealing differences between the used software packages. On the other side, we show that asymmetrical error contributions are highly correlated with the satellite constellation and the geographical location. References: Geiger A. (1988): Modeling of Phase Centre Variation and its Influence on GPS-Positioning, In GPS-Techniques Applied to Geodesy and Surveying, Lecture Notes in

  3. Analytical model of the ablative Rayleigh-Taylor instability in the deceleration phase

    International Nuclear Information System (INIS)

    A sharp boundary model for the deceleration phase of imploding capsules in inertial confinement fusion, in both direct and indirect drive, has been developed. The model includes heat conduction, local α-particle energy deposition, and shell compressibility effects. A differential equation for the temporal evolution of the modal amplitude interface is obtained. It is found that the α-particle energy has a strong influence on the evolution of the low l modes, via the compressibility of the shell. The modes are damped by vorticity convection, fire polishing, and α-particle energy deposition. The existence of a cutoff l number arises from the high blow of velocity into the hot region (rocket effect) if density gradient scale length effects are taken into account at the interface. The differential equation for the modal amplitude is used as a postprocessor to the results of 1D-SARA code [J. J. Honrubia, J. Quant. Spectrosc. Radiat. Transfer. 49, 491 (1993)] in a typical capsule for indirect-drive ignition designed on the National Ignition Facility. It is found that modes with l>180 are completely stabilized. The results are in agreement with two-dimensional simulations

  4. Analytical model of the ablative Rayleigh-Taylor instability in the deceleration phase

    Science.gov (United States)

    Sanz, J.; Betti, R.

    2005-04-01

    A sharp boundary model for the deceleration phase of imploding capsules in inertial confinement fusion, in both direct and indirect drive, has been developed. The model includes heat conduction, local α-particle energy deposition, and shell compressibility effects. A differential equation for the temporal evolution of the modal amplitude interface is obtained. It is found that the α-particle energy has a strong influence on the evolution of the low l modes, via the compressibility of the shell. The modes are damped by vorticity convection, fire polishing, and α-particle energy deposition. The existence of a cutoff l number arises from the high blow of velocity into the hot region (rocket effect) if density gradient scale length effects are taken into account at the interface. The differential equation for the modal amplitude is used as a postprocessor to the results of 1D-SARA code [J. J. Honrubia, J. Quant. Spectrosc. Radiat. Transfer. 49, 491 (1993)] in a typical capsule for indirect-drive ignition designed on the National Ignition Facility. It is found that modes with l >180 are completely stabilized. The results are in agreement with two-dimensional simulations.

  5. Chemical reactions at aqueous interfaces

    Science.gov (United States)

    Vecitis, Chad David

    2009-12-01

    Interfaces or phase boundaries are a unique chemical environment relative to individual gas, liquid, or solid phases. Interfacial reaction mechanisms and kinetics are often at variance with homogeneous chemistry due to mass transfer, molecular orientation, and catalytic effects. Aqueous interfaces are a common subject of environmental science and engineering research, and three environmentally relevant aqueous interfaces are investigated in this thesis: 1) fluorochemical sonochemistry (bubble-water), 2) aqueous aerosol ozonation (gas-water droplet), and 3) electrolytic hydrogen production and simultaneous organic oxidation (water-metal/semiconductor). Direct interfacial analysis under environmentally relevant conditions is difficult, since most surface-specific techniques require relatively `extreme' conditions. Thus, the experimental investigations here focus on the development of chemical reactors and analytical techniques for the completion of time/concentration-dependent measurements of reactants and their products. Kinetic modeling, estimations, and/or correlations were used to extract information on interfacially relevant processes. We found that interfacial chemistry was determined to be the rate-limiting step to a subsequent series of relatively fast homogeneous reactions, for example: 1) Pyrolytic cleavage of the ionic headgroup of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) adsorbed to cavitating bubble-water interfaces during sonolysis was the rate-determining step in transformation to their inorganic constituents carbon monoxide, carbon dioxide, and fluoride; 2) ozone oxidation of aqueous iodide to hypoiodous acid at the aerosol-gas interface is the rate-determining step in the oxidation of bromide and chloride to dihalogens; 3) Electrolytic oxidation of anodic titanol surface groups is rate-limiting for the overall oxidation of organics by the dichloride radical. We also found chemistry unique to the interface, for example: 1

  6. An analytical method for modeling two-phase gravity-driven drainage systems in BOP applications

    International Nuclear Information System (INIS)

    Highlights: ► An actual gravity drainage system in an operating power plant is described. ► A drain flow oscillation exists in the system, which is replicated using RELAP5. ► The RELAP model identifies that steam binding due to poor venting is the cause. ► The RELAP model shows that new vent piping prevents the flow oscillations. ► The revised vent piping is installed in the plant and resolves the flow oscillations. - Abstract: Two-phase gravity-driven drainage systems are used in many applications within nuclear power Balance of Plant (BOP) applications such as the drain lines for moisture separator re-heaters (MSRs) and feedwater heaters. Design of these systems is typically based on industry-oriented guidelines and operator-based experience. Changes in plant operation, such as uprates and equipment modification and/or replacement, are relatively common as plants seek to generate more power with greater efficiency. These plant modifications may inadvertently change system operation from design conditions and impose undesirable system transients. This paper seeks to provide a method for analyzing BOP drainage systems in an effort to characterize and mitigate drain flow transients. Previous methodologies diagnose and evaluate drain instability through measurement, empirical analysis, and operational experience. This paper identifies methods that can be utilized to generate computational models of discrete plant drainage systems that decrease the level of speculation involved in previous analyses. Additionally, a real-world application of this method is presented to demonstrate how computer modeling can accurately mimic plant transients.

  7. Chitosan-Coated Magnetic Nanoparticles Prepared in One-Step by Precipitation in a High-Aqueous Phase Content Reverse Microemulsion

    Directory of Open Access Journals (Sweden)

    María Guadalupe Pineda

    2014-07-01

    Full Text Available Chitosan-coated magnetic nanoparticles (CMNP were prepared in one-step by precipitation in a high-aqueous phase content reverse microemulsion in the presence of chitosan. The high-aqueous phase concentration led to productivities close to 0.49 g CMNP/100 g microemulsion; much higher than those characteristic of precipitation in reverse microemulsions for preparing magnetic nanoparticles. The obtained nanoparticles present a narrow particle size distribution with an average diameter of 4.5 nm; appearing to be formed of a single crystallite; furthermore they present superparamagnetism and high magnetization values; close to 49 emu/g. Characterization of CMNP suggests that chitosan is present as a non-homogeneous very thin layer; which explains the slight reduction in the magnetization value of CMNP in comparison with that of uncoated magnetic nanoparticles. The prepared nanoparticles show high heavy ion removal capability; as demonstrated by their use in the treatment of Pb2+ aqueous solutions; from which lead ions were completely removed within 10 min.

  8. Chitosan-coated magnetic nanoparticles prepared in one-step by precipitation in a high-aqueous phase content reverse microemulsion.

    Science.gov (United States)

    Pineda, María Guadalupe; Torres, Silvia; López, Luis Valencia; Enríquez-Medrano, Francisco Javier; de León, Ramón Díaz; Fernández, Salvador; Saade, Hened; López, Raúl Guillermo

    2014-01-01

    Chitosan-coated magnetic nanoparticles (CMNP) were prepared in one-step by precipitation in a high-aqueous phase content reverse microemulsion in the presence of chitosan. The high-aqueous phase concentration led to productivities close to 0.49 g CMNP/100 g microemulsion; much higher than those characteristic of precipitation in reverse microemulsions for preparing magnetic nanoparticles. The obtained nanoparticles present a narrow particle size distribution with an average diameter of 4.5 nm; appearing to be formed of a single crystallite; furthermore they present superparamagnetism and high magnetization values; close to 49 emu/g. Characterization of CMNP suggests that chitosan is present as a non-homogeneous very thin layer; which explains the slight reduction in the magnetization value of CMNP in comparison with that of uncoated magnetic nanoparticles. The prepared nanoparticles show high heavy ion removal capability; as demonstrated by their use in the treatment of Pb2+ aqueous solutions; from which lead ions were completely removed within 10 min. PMID:24991759

  9. X-ray Amorphous Phases in Antarctica Dry Valley Soils: Insight into Aqueous Alteration Processes on Mars?

    Science.gov (United States)

    Ming, D. W.; Morris, R. V.; Rampe, E. B.; Quinn, J. E.; Graff, T. G.

    2015-12-01

    The Chemistry and Mineralogy (CheMin) instrument onboard the Mars Curiosity rover has detected abundant amounts (approx. 25-30 wt. %) of X-ray amorphous materials in a windblown deposit (Rocknest) and in a sedimentary mudstone (Cumberland and John Klein) in Gale crater. On Earth, X-ray amorphous components are common in soils and sediments, but usually not as abundant as detected in Gale crater. One hypothesis for the abundant X-ray amorphous materials on Mars is limited interaction of liquid water with surface materials, kinetically inhibiting maturation to more crystalline phases. The objective of this study was to characterize the chemistry and mineralogy of soils formed in the Antarctica Dry Valleys, one of the driest locations on Earth. Two soils were characterized from different elevations, including a low elevation, coastal, subxerous soil in Taylor Valley and a high elevation, ultraxerous soil in University Valley. A variety of techniques were used to characterize materials from each soil horizon, including Rietveld analysis of X-ray diffraction data. For Taylor Valley soil, the X-ray amorphous component ranged from about 4 wt. % in the upper horizon to as high as 15 wt. % in the lowest horizon just above the permafrost layer. Transmission electron microscopy indicated that the presence of short-range ordered (SRO) smectite was the most likely candidate for the X-ray amorphous materials in the Taylor Valley soils. The SRO smectite is likely an aqueous alteration product of mica inherited from granitic materials during glaciation of Taylor Valley. The drier University Valley soil had lower X-ray amorphous contents of about 5 wt. % througout the profile. The X-ray amorphous materials in University Valley are attributed to nanoparticles of TiO2 and possibly amorphous SiO2. The high abundance of X-ray amorphous materials in Taylor Valley is surprising for one of the driest places on Earth. These materials may have been physically and chemical altered during

  10. Ni(II) ion-imprinted solid-phase extraction and preconcentration in aqueous solutions by packed-bed columns

    International Nuclear Information System (INIS)

    Solid-phase extraction (SPE) columns packed with materials based on molecularly imprinted polymers (MIPs) were used to develop selective separation and preconcentration for Ni(II) ion from aqueous solutions. SPE is more rapid, simple and economical method than the traditional liquid-liquid extraction. MIPs were used as column sorbent to increase the grade of selectivity in SPE columns. In this study, we have developed a polymer obtained by imprinting with Ni(II) ion as a ion-imprinted SPE sorbent. For this purpose, NI(II)-methacryloylhistidinedihydrate (MAH/Ni(II)) complex monomer was synthesized and polymerized with cross-linking ethyleneglycoldimethacrylate to obtain [poly(EGDMA-MAH/Ni(II))]. Then, Ni(II) ions were removed from the polymer getting Ni(II) ion-imprinted sorbent. The MIP-SPE preconcentration procedure showed a linear calibration curve within concentration range from 0.3 to 25 ng/ml and the detection limit was 0.3 ng/ml (3 s) for flame atomic absorption spectrometry (FAAS). Ni(II) ion-imprinted microbeads can be used several times without considerable loss of adsorption capacity. When the adsorption capacity of nickel imprinted microbeads were compared with non-imprinted microbeads, nickel imprinted microbeads have higher adsorption capacity. The Kd (distribution coefficient) values for the Ni(II)-imprinted microbeads show increase in Kd for Ni(II) with respect to both Kd values of Zn(II), Cu(II) and Co(II) ions and non-imprinted polymer. During that time Kd decreases for Zn(II), Cu(II) and Co(II) ions and the k' (relative selectivity coefficient) values which are greater than 1 for imprinted microbeads of Ni(II)/Cu(II), Ni(II)/Zn(II) and Ni(II)/Co(II) are 57.3, 53.9, and 17.3, respectively. Determination of Ni(II) ion in sea water showed that the interfering matrix had been almost removed during preconcentration. The column was good enough for Ni determination in matrixes containing similar ionic radii ions such as Cu(II), Zn(II) and Co(II)

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

    Science.gov (United States)

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

    2016-04-01

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

  12. The salting-out effect and phase separation in aqueous solutions of tri-sodium citrate and 1-butyl-3-methylimidazolium bromide

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Rahmat, E-mail: rsadeghi@uok.ac.i [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Golabiazar, Roonak [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Shekaari, Hemayat [Department of Chemistry, Faculty of Science, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of)

    2010-04-15

    The aim of this work is to obtain further evidence about the salting-out effect produced by the addition of tri-sodium citrate to aqueous solutions of water miscible ionic liquid 1-butyl-3-methylimidazolium bromide ([C{sub 4}mim][Br]) by evaluating the effect of tri-sodium citrate on the thermodynamic properties of aqueous solutions of this ionic liquid. Experimental measurements of density and sound velocity at different temperatures ranging from (288.15 to 308.15) K, the refractive index at 308.15 K and the liquid-liquid phase diagram at different temperatures ranging from (288.15 to 338.15) K for aqueous solutions containing 1-butyl-3-methylimidazolium bromide ([C{sub 4}mim][Br]) and tri-sodium citrate (Na{sub 3}Cit) are taken. The apparent molar volume of transfer of [C{sub 4}mim][Br] from water to aqueous solutions of Na{sub 3}Cit have positive values and it increases by increasing salt molality. Although at high IL molality, the apparent molar isentropic compressibility shows similar behaviour with that of the apparent molar volume. However at low concentrations of IL, the apparent molar isentropic compressibility of transfer of [C{sub 4}mim][Br] from water to aqueous solutions of Na{sub 3}Cit have negative values. The effects of temperature and the addition of Na{sub 3}Cit and [C{sub 4}mim][Br] on the liquid-liquid phase diagram of the investigated system have been studied. It was found that an increase in temperature caused the expansion of the one-phase region. The presence of Na{sub 3}Cit triggers a salting-out effect, leading to significant upward shifts of the liquid-liquid de-mixing temperatures of the system. The effect of temperature on the phase-forming ability in the system investigated has been studied based on a salting-out coefficient obtained from fitting the binodal values to a Setschenow-type equation for each temperature. Based on cloud point values, the energetics of the clouding process have been estimated and it was found that both of

  13. The salting-out effect and phase separation in aqueous solutions of tri-sodium citrate and 1-butyl-3-methylimidazolium bromide

    International Nuclear Information System (INIS)

    The aim of this work is to obtain further evidence about the salting-out effect produced by the addition of tri-sodium citrate to aqueous solutions of water miscible ionic liquid 1-butyl-3-methylimidazolium bromide ([C4mim][Br]) by evaluating the effect of tri-sodium citrate on the thermodynamic properties of aqueous solutions of this ionic liquid. Experimental measurements of density and sound velocity at different temperatures ranging from (288.15 to 308.15) K, the refractive index at 308.15 K and the liquid-liquid phase diagram at different temperatures ranging from (288.15 to 338.15) K for aqueous solutions containing 1-butyl-3-methylimidazolium bromide ([C4mim][Br]) and tri-sodium citrate (Na3Cit) are taken. The apparent molar volume of transfer of [C4mim][Br] from water to aqueous solutions of Na3Cit have positive values and it increases by increasing salt molality. Although at high IL molality, the apparent molar isentropic compressibility shows similar behaviour with that of the apparent molar volume. However at low concentrations of IL, the apparent molar isentropic compressibility of transfer of [C4mim][Br] from water to aqueous solutions of Na3Cit have negative values. The effects of temperature and the addition of Na3Cit and [C4mim][Br] on the liquid-liquid phase diagram of the investigated system have been studied. It was found that an increase in temperature caused the expansion of the one-phase region. The presence of Na3Cit triggers a salting-out effect, leading to significant upward shifts of the liquid-liquid de-mixing temperatures of the system. The effect of temperature on the phase-forming ability in the system investigated has been studied based on a salting-out coefficient obtained from fitting the binodal values to a Setschenow-type equation for each temperature. Based on cloud point values, the energetics of the clouding process have been estimated and it was found that both of entropy and enthalpy are the driving forces for biphasic

  14. Design and In Vitro Evaluation of a New Nano-Microparticulate System for Enhanced Aqueous-Phase Solubility of Curcumin

    Directory of Open Access Journals (Sweden)

    Diana Guzman-Villanueva

    2013-01-01

    Full Text Available Curcumin, a yellow polyphenol derived from the turmeric Curcuma longa, has been associated with a diverse therapeutic potential including anti-inflammatory, antioxidant, antiviral, and anticancer properties. However, the poor aqueous solubility and low bioavailability of curcumin have limited its potential when administrated orally. In this study, curcumin was encapsulated in a series of novel nano-microparticulate systems developed to improve its aqueous solubility and stability. The nano-microparticulate systems are based entirely on biocompatible, biodegradable, and edible polymers including chitosan, alginate, and carrageenan. The particles were synthesized via ionotropic gelation. Encapsulating the curcumin into the hydrogel nanoparticles yielded a homogenous curcumin dispersion in aqueous solution compared to the free form of curcumin. Also, the in vitro release profile showed up to 95% release of curcumin from the developed nano-microparticulate systems after 9 hours in PBS at pH 7.4 when freeze-dried particles were used.

  15. Quaternary (liquid + liquid) equilibria of aqueous two-phase poly (ethylene glycol), poly (DMAM-TBAM), and KH2PO4: Experimental and generalized Flory-Huggins theory

    International Nuclear Information System (INIS)

    Quaternary (liquid + liquid) equilibrium (LLE) data of the aqueous two-phase poly (ethylene glycol), poly (N,N-dimethylacrylamide-t-butylacrylamide) with abbreviation name poly (DMAM-TBAM) as a hydrophobic association water-soluble copolymer and KH2PO4 has been determined experimentally at T = 338.15 K. Furthermore, the generalized Flory-Huggins theory with two electrostatic terms (the Debye-Hueckel and Pitzer-Debye-Hueckel) was used for correlation of the phase behavior of the quaternary system and the interaction parameters between all species were calculated. It was found that addition of poly (DMAM-TBAM) copolymer as well as changing the temperature can shift the binodal curves of aqueous two-phase systems containing polyethylene glycol (PEG) and salt. Also, the phase behavior of the DMAM-TBAM copolymer with some salts containing sodium chloride, ammonium hydrogen phosphate, potassium hydrogen phosphate, and sodium carbonate were studied experimentally at T = 338.15 K and the effect of the salt type on the their binodal curves was determined

  16. Develop of analytic method for the determination of vitamin D3 in multivitaminics and minerals using chromatography it liquidates of high efficiency in normal phase with ultraviolet detection

    International Nuclear Information System (INIS)

    The good chromatography conditions settled down for the determination vitamin D3 in multivitaminic samples by means of the analytic technique of chromatography it liquidates of high efficiency (HPLC) in normal phase, with ultraviolet detection to 265 nm. The best conditions in the proposed methodology settled down and the variables of analytic acting were validated, for the analytic quantification of vitamin D3 in International units. The applicability of the methodology was demonstrated in the vitamin determination D3 in multivitaminis samples in pill form

  17. Experimental measurement and modeling of the distribution of solvent and ions between an aqueous phase and an ion exchange resin

    DEFF Research Database (Denmark)

    Christensen, Søren Gregers; Thomsen, Kaj

    2005-01-01

    The distribution of solutes and solvent between an aqueous solution of salt and an ion exchange resin has been measured at ambient temperature. The experiments have been performed for aqueous solutions of KNO3, KCl, Ca(NO3)2 and CaCl2 in the concentration range of 0-3N. The absorption has been...... measured for 3 gel type and 3 macroreticular resins with a degree of crosslinking varying from 10.5 to 18.5%. The experimental results have been modeled with the Extended UNIQUAC model combined with an elastic term taking the elastic properties of the resin structure into account. The model shows very good...

  18. Batch, Kinetic and Equilibrium Studies of Chromium (Vi From Aqueous Phase Using Activated Carbon Derived From Lantana Camara Fruit

    Directory of Open Access Journals (Sweden)

    K. Nithya

    2015-12-01

    Full Text Available Batch experiments have been conducted to determine the maximum adsorption capacity of activated carbon derived from Lantana camara fruit to remove hexavalent chromium from aqueous solution. The removal efficiency and uptake capacity of the biosorbent were determined by varying several batch level parameters. Highest removal efficiency of the biosorbent was found to be almost 99% under optimal conditions. Maximum monolayer adsorption capacity was determined to be 86 mg/g. The experimental data best fitted with Langmuir adsorption isotherm and pseudo second order model. These findings conclude that the selected biosorbent has more promising features in binding hexavalent chromium in aqueous media.

  19. Extraction of Theanine from Waste Liquid of Tea Polyphenol Production in Aqueous Two-phase Systems with Cationic and Anionic Surfactants

    Institute of Scientific and Technical Information of China (English)

    ZHANG Junwei; WANG Yan; PENG Qijun

    2013-01-01

    Extraction of theanine from waste liquid of tea polyphenol production was studied in aqueous surfactant two-phase system (ASTP) with cationic suffactant (CTAB) and anionic surfactant (SDS).Results indicate that the region of ASTP is narrow and there is only a two-phase region of cationic surfactant.The increase in concentrations of NaBr and Na2SO4 are beneficial to the formation of ASTP.Theanine concentration in the bottom phase increases with increasing concentration of theanine,whereas the partition coefficient and extraction rate only change a little when the concentration of theanine is above 0.2 g· L-1.With the increase of SDS concentration,the phase ratio and the partition coefficient decrease,while the extraction efficiency of theanine increases and the concentration of theaninc changes a little in the range from 2.4/7.5 to 2.8/7.2 for SDS/CTAB ratio.The temperature has a notable effect on the concentration of theanine in the bottom phase,partition coefficient and extraction rate of theanine.The increase of waste liquid decreases the phase ratio,increases the concentration and extraction rate of theanine in the bottom phase,since the protein and the saccharide enter the bottom phase with theanine.

  20. Insights into secondary organic aerosol formed via aqueous-phase reactions of phenolic compounds based on high resolution mass spectrometry

    Directory of Open Access Journals (Sweden)

    Y. Sun

    2010-02-01

    Full Text Available Recent work has shown that aqueous-phase reactions of phenolic compounds – phenol (C6H6O, guaiacol (C7H8O2, and syringol (C8H10O3 – can form secondary organic aerosol (SOA at high yields. Here we examine the chemical characteristics of this SOA and its formation mechanisms using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-AMS, an Ion Chromatograph (IC, and a Total Organic Carbon (TOC analyzer. The phenolic SOA are highly oxygenated with oxygen-to-carbon (O/C ratios in the range of 0.80–1.06 and carbon oxidation states (=2×O/C–H/C between −0.14 and +0.47. The organic mass-to-carbon (OM/OC ratios determined by the HR-AMS (=2.21���2.55 agree well with values determined based on the SOA mass measured gravimetrically and the OC mass from the TOC analyzer. Both the O/C and OM/OC ratios of the phenolic SOA are similar to the values observed for ambient low-volatility oxygenated/secondary OA (LV-OOA. Oxalate is a minor, but ubiquitous, component of the SOA formed from all three phenolic precursors, accounting for 1.4–5.2% of the SOA mass, with generally higher yields in experiments with H2O2 added as an ·OH source compared to without. The AMS spectra show evidence for the formation of syringol and guaiacol dimers and higher oligomers via C–C and C–O coupling of phenoxyl radicals, which are formed through oxidation pathways such as abstraction of the phenolic hydrogen atom or ·OH addition to the aromatic ring. This latter pathway leads to hydroxylation of the aromatic ring, which is one mechanism that increases the degree of oxidation of the SOA products. Compared to direct photochemical reactions of the phenols, ·OH-initiated reactions favor the formation of smaller oxidation products but less dimers or higher oligomers. Two unique and prominent ions in the syringol and guaiacol SOA spectra,

  1. Suitable image parameters and analytical method for quantitatively measuring cerebral blood flow volume with phase-contrast magnetic resonance imaging

    International Nuclear Information System (INIS)

    The aim of this study was to determine suitable image parameters and an analytical method for phase-contrast magnetic resonance imaging (PC-MRI) as a means of measuring cerebral blood flow volume. This was done by constructing an experimental model and applying the results to a clinical application. The experimental model was constructed from the aorta of a bull and circulating isotonic saline. The image parameters of PC-MRI (repetition time, flip angle, matrix, velocity rate encoding, and the use of square pixels) were studied with percent flow volume (the ratio of actual flow volume to measured flow volume). The most suitable image parameters for accurate blood flow measurement were as follows: repetition time, 50 msec; flip angle, 20 degrees; and a 512 x 256 matrix without square pixels. Furthermore, velocity rate encoding should be set ranging from the maximum flow velocity in the vessel to five times this value. The correction in measuring blood flow was done with the intensity of the region of interest established in the background. With these parameters for PC-MRI, percent flow volume was greater than 90%. Using the image parameters for PC-MRI and the analytical method described above, we evaluated cerebral blood flow volume in 12 patients with occlusive disease of the major cervical arteries. The results were compared with conventional xenon computed tomography. The values found with both methods showed good correlation. Thus, we concluded that PC-MRI was a noninvasive method for evaluating cerebral blood flow in patients with occlusive disease of the major cervical arteries. (author)

  2. An efficient method for synthesis of phenacyl derivatives under homogeneous phase transfer catalyst condition in aqueous media

    Institute of Scientific and Technical Information of China (English)

    Soheil Sayyahi; Jafar Saghanezhad

    2011-01-01

    In this letter, a mild and efficient procedure for synthesis of phenacyl derivatives under homogenous catalysis in the presence of tetrabutylammonium bromide in aqueous media is described. The nucleophilic substitution reactions were performed under ecofriendly conditions and gave the corresponding products in high yields and short reaction times.

  3. Characterizing Fullerene Nanoparticles in Aqueous Suspensions

    Science.gov (United States)

    Studies have indicated that fullerenes can form stable colloidal suspensions in water when introduced to the aqueous phase through solvent exchange, sonication, or extended mixing. The colloidal suspensions created using these techniques have effective aqueous phase concentratio...

  4. Calculation of liquid-liquid equilibrium of aqueous two-phase systems using a chemical-theory-based excess Gibbs energy model

    Directory of Open Access Journals (Sweden)

    Pessôa Filho P. A.

    2004-01-01

    Full Text Available Mixtures containing compounds that undergo hydrogen bonding show large deviations from ideal behavior. These deviations can be accounted for through chemical theory, according to which the formation of a hydrogen bond can be treated as a chemical reaction. This chemical equilibrium needs to be taken into account when applying stability criteria and carrying out phase equilibrium calculations. In this work, we illustrate the application of the stability criteria to establish the conditions under which a liquid-phase split may occur and the subsequent calculation of liquid-liquid equilibrium using a chemical-theory-modified Flory-Huggins equation to describe the non ideality of aqueous two-phase systems composed of poly(ethylene glycol and dextran. The model was found to be able to correlate ternary liquid-liquid diagrams reasonably well by simple adjustment of the polymer-polymer binary interaction parameter.

  5. Chemical characterization of SOA formed from aqueous-phase reactions of phenols with the triplet excited state of carbonyl and hydroxyl radical

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Lu; Smith, Jeremy; Laskin, Alexander; Anastasio, Cort N.; Laskin, Julia; Zhang, Qi

    2014-01-01

    Phenolic compounds, which are emitted in significant amounts from biomass burning, can undergo fast reactions in atmospheric aqueous phases to form secondary organic aerosol (aqSOA). In this study, we investigate the reactions of phenol and two methoxy-phenols (syringol and guaiacol) with two major aqueous phase oxidants – the triplet excited states of an aromatic carbonyl (3C*) and hydroxyl radical (•OH). We thoroughly characterize the low-volatility species produced from these reactions and interpret their formation mechanisms using aerosol mass spectrometry (AMS), desorption electrospray ionization mass spectrometry (DESIMS), and ion chromatography (IC). A large number of oxygenated molecules are identified, including oligomers containing up to six monomer units, functionalized monomer and oligomers with carbonyl, carboxyl, and hydroxyl groups, and small organic acid anions (e.g., formate, acetate, oxalate, and malate). The average atomic oxygen-to-carbon (O/C) ratios of phenolic aqSOA are in the range of 0.85-1.23, similar to those of low-volatility oxygenated organic aerosol (LV-OOA) observed in ambient air. The aqSOA compositions are overall similar for the same precursor, but the reactions mediated by 3C* are faster than •OH-mediated reactions and produce more oligomers and hydroxylated species at the point when 50% of the phenol had reacted. Profiles determined using a thermodenuder indicate that the volatility of phenolic aqSOA is influenced by both oligomer content and O/C ratio. In addition, the aqSOA shows enhanced light absorption in the UV-vis region, suggesting that aqueous-phase reactions of phenols are likely an important source of brown carbon in the atmosphere, especially in regions influenced by biomass burning.

  6. Application of headspace solid-phase microextraction followed by gas chromatography–mass spectrometry to determine short-chain alkane monocarboxylic acids in aqueous samples

    OpenAIRE

    Banel, Anna; Wasielewska, Marta; Zygmunt, Bogdan

    2010-01-01

    In this study, a procedure was developed to determine short-chain alkane monocarboxylic acids (SCMAs) in aqueous samples using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography (GC) coupled with mass spectrometry (MS). A Stabilwax-DA capillary column (30 m × 0.32-mm inner diameter, 0.50-μm film thickness) was used for GC separation and a 60-μm poly(ethylene glycol) fiber was used to isolate SCMAs from water and introduce them into the gas chromatograph. Parameters...

  7. Influence of NO2 and metal ions on oxidation of aqueous-phase S(IV in atmospheric concentrations

    Directory of Open Access Journals (Sweden)

    Cláudia R. Martins

    2008-06-01

    Full Text Available An investigation was made of the influence of atmospheric concentrations (15 or 130 ppbv of NO2 on the aqueous-phase oxidation rate of S(IV in the presence and absence of Fe(III, Mn(II and Cr(VI metal ions under controlled experimental conditions (pH, T, concentration of reactants, etc.. The reaction rate in the presence of the NO2 flow was slower than the reaction rate using only clean air with an initial S(IV concentration of 10-4 mol/L. NO2 appears to react with S(IV, producing a kind of inhibitor that slows down the reaction. Conversely, tenfold lower concentrations of S(IV ([S(IV]º = 10-5 mol/L caused a faster reaction in the presence of NO2 than the reaction using purified air. Under these conditions, therefore, the equilibrium shifts to sulfate formation. With the addition of Fe(III, Mn(II or Cr(VI in the presence of a NO2 flow, the reaction occurred faster under all the conditions in which S(IV oxidation was investigated.A reação de oxidação de S(IV em fase aquosa foi estudada em laboratório em presença de NO2 dos íons metálicos Fe(III, Mn(II, e Cr(VI sob condições experimentais controladas (pH, T, concentração dos reagentes, etc.. Na presença de corrente de ar com NO2 (15 ou 130 ppbv a reação de oxidação de S(IV ocorreu mais lentamente do que na presença de ar purificado, para uma concentração inicial de S(IV de 10-4 mol/L. Ao contrário, para concentração inicial de S(IV dez vezes menor ([S(IV]° = 10-5 mol/L a reação ocorreu mais rapidamente na presença de NO2. A explicação está relacionada com o equilíbrio envolvendo a formação de espécies intermediárias de longa vida, que impedem o prosseguimento da reação, porém a depender das concentrações relativas de S(IV e NO2, essas espécies se decompõem deslocando o equilíbrio no sentido de formação de sulfato. A adição dos íons Fe(III, Mn(II ou Cr(VI em presença de corrente de ar com NO2 indicou atividade catalítica para esses íons, em todas

  8. Liquid-Phase Synthesis of Ba2V2O7 Phosphor Powders and Films Using Immiscible Biphasic Organic-Aqueous Systems.

    Science.gov (United States)

    Takahashi, Mami; Hagiwara, Manabu; Fujihara, Shinobu

    2016-08-15

    A liquid-phase synthesis of inorganic phosphor materials at a moderate temperature was proposed by using immiscible liquid-liquid biphasic systems. A self-activated Ba2V2O7 phosphor was actually synthesized from vanadium alkoxide dissolved in an organic solution and barium acetate in an aqueous solution. A mild hydrolysis reaction of the alkoxide started at the organic-inorganic interface, and an intermediate compound, Ba(VO3)2·H2O, was initially formed. Ba2V2O7 powders were then obtained by the conversion from Ba(VO3)2·H2O promoted in the aqueous solution. Ba2V2O7 films were obtained on surface-modified silica glass substrates through the similar chemical reactions. Factors such as the surface state of substrates, the kind of organic solvents, and the volume of aqueous solutions were examined to improve the film deposition behavior. The resultant Ba2V2O7 materials showed broad-band visible photoluminescence upon irradiation with ultraviolet light based on the charge transfer transition in the VO4(3-) units existing as dimers. PMID:27472450

  9. A Semi-Analytic Model of a Buoyant Flame Bubble Propagation During the Deflagration Phase of a Type Ia Supernova

    Science.gov (United States)

    Jumper, Kevin; Fisher, Robert

    2012-03-01

    Type Ia supernovae are astronomical events in which a white dwarf, the cold remnant of a star that has exhausted its hydrogen fuel, detonates and briefly produces an explosion brighter than most galaxies. Many researchers think that they could occur as the white dwarf approaches a critical mass of 1.4 solar masses by accreting matter from a companion main sequence star, a scenario that is referred to as the single-degenerate channel. Assuming such a progenitor, we construct a semi-analytic model of the propagation of a flame bubble ignited at a single off-center point within the white dwarf. The bubble then rises under the influences of buoyancy and drag, burning the surrounding fuel material in a process called deflagration. We contrast the behavior of the deflagration phase in the presence of a physically high Reynolds number regime with the low Reynolds number regimes inherent to three-dimensional simulations, which are a consequence of numerical viscosity. Our work may help validate three-dimensional deflagration results over a range of initial conditions.

  10. Expressions for multilinear combined pH/organic solvent elution of ionizable analytes in reversed-phase HPLC.

    Science.gov (United States)

    Zisi, Ch; Fasoula, S; Pappa-Louisi, A; Nikitas, P

    2013-10-15

    Expressions for the retention time of ionogenic analytes eluted under multilinear double pH/solvent-gradients in reversed-phase liquid chromatography are developed by dividing each gradient profile into a finite number of subportions, where the solute retention factors or their logarithms vary linearly with time. To test the theory, two series of experimental gradient retention data of amino acid OPA derivatives were analyzed: The first one was a monolinear or bilinear pH-gradient data set obtained in eluents with different but constant organic modifier contents, whereas the second data set comprised retention data of combined pH/organic solvent-gradients, where the organic content was changed linearly with time but the variation of pH exhibited a curved form approximated by five linear subportions. It was found that the derived expressions describe these experimental retention data with high accuracy, since under double pH/solvent-gradients the overall errors in the fitted and predicted retention times were 1.9% and 1.7%, respectively, whereas under simple pH-gradients these errors were 0.9% and 2%, respectively. PMID:24010983

  11. Formation and Dynamics of Ion-Stabilized Gas Nanobubble Phase in the Bulk of Aqueous NaCl Solutions.

    Science.gov (United States)

    Bunkin, Nikolai F; Shkirin, Alexey V; Suyazov, Nikolay V; Babenko, Vladimir A; Sychev, Andrey A; Penkov, Nikita V; Belosludtsev, Konstantin N; Gudkov, Sergey V

    2016-02-25

    Ion-stabilized gas nanobubbles (the so-termed "bubstons") and their clusters are investigated in bulk aqueous solutions of NaCl at different ion concentrations by four independent laser diagnostic methods. It turned out that in the range of NaCl concentration 10(-6) stirrer at different stirring rates. Different regimes of the bubston generation, resulting from various techniques of processing the liquid samples, were explored. PMID:26849451

  12. Optimization of the Parameters Affecting the Fenton Process for Decolorization of Reactive Red 198 (RR-198) from the Aqueous Phase

    OpenAIRE

    Mansooreh Dehghani; Mahshid Ghadami; Talat Gholami; Marzieh Ansari Shiri; Zahra Elhameyan; Mohammad Reza Javaheri; Narges Shamsedini; Samaneh Shahsavani

    2015-01-01

    Background: Recently, there has been a great concern about the consumption of dyes because of their toxicity, mutagenicity, carcinogenicity, and persistence in the aquatic environment. Reactive dyes are widely used in textile industry. Advanced oxidation processes are one of the cost-effective methods for the removal of these dyes. The main aims of this study were determining the feasibility of using Fenton process in removing Reactive Red 198 (RR-198) dye from aqueous so...

  13. A microdevice assisted approach for the preparation, characterization and selection of continuous aqueous two-phase systems: from micro to bench-scale.

    Science.gov (United States)

    Vázquez-Villegas, Patricia; Ouellet, Eric; González, Claudia; Ruiz-Ruiz, Federico; Rito-Palomares, Marco; Haynes, Charles A; Aguilar, Oscar

    2016-07-01

    Aqueous two-phase systems (ATPS) have emerged as an alternative strategy for the recovery and purification of a wide variety of biological products. Typical process development requires a large screening of experimental conditions towards industrial adoption where continuous processes are preferred. In this work, it was proved that under certain flow conditions, ATPS could be formed continuously inside a microchannel, starting from stocks of phase components. Staggered herringbone chaotic micromixers included within the device sequentially and rapidly prepare two-phase systems across an entire range of useful phase compositions. Two-phase diagrams (binodal curves) were easily plotted using the cloud-point method for systems of different components and compared with previously reported curves for each system, proving that phase formation inside the device correlated with the previously reported diagrams. A proof of concept for sample partitioning in such a microdevice was performed with two different experimental models: BSA and red blood cells. Finally, the microdevice was employed to obtain information about the recovery and partition coefficient of invertase from a real complex mixture of proteins (yeast extract) to design a process for the recovery of the enzyme selecting a suitable system and composition to perform the process at bench-scale. PMID:27302418

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

    Science.gov (United States)

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

    2013-03-15

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

  15. SPIDIA-DNA: An External Quality Assessment for the pre-analytical phase of blood samples used for DNA-based analyses

    Czech Academy of Sciences Publication Activity Database

    Malentacchi, F.; Pazzagli, M.; Simi, L.; Orlando, C.; Wyrich, R.; Hartmann, C.C.; Verderio, P.; Pizzamiglio, S.; Ciniselli, C.M.; Tichopád, Aleš; Kubista, Mikael; Gelmini, S.

    -, č. 424 (2013), s. 274-286. ISSN 0009-8981 Institutional research plan: CEZ:AV0Z50520701 Keywords : Pre-analytical phase * DNA quality * Blood samples Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.764, year: 2013

  16. SPIDIA-RNA: First external quality assessment for the pre-analytical phase of blood samples used for RNA based analyses

    Czech Academy of Sciences Publication Activity Database

    Pazzagli, M.; Malentacchi, F.; Simi, L.; Wyrich, R.; Guenther, K.; Hartmann, C.; Verderio, P.; Pizzamiglio, S.; Ciniselli, C.M.; Tichopád, Aleš; Kubista, Mikael; Gelmini, S.

    2013-01-01

    Roč. 59, č. 1 (2013), s. 20-31. ISSN 1046-2023 Institutional research plan: CEZ:AV0Z50520701 Keywords : Pre-analytical phase * RNA quality * Blood samples Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.221, year: 2013

  17. Comparison of Various Types of Stationary Phases in Non-Aqueous Reversed-Phase High-Performance Liquid Chromatography–Mass Spectrometry of Glycerolipids in Blackcurrant Oil and Its Enzymatic Hydrolysis Mixture

    Czech Academy of Sciences Publication Activity Database

    Lísa, M.; Holčapek, M.; Sovová, Helena

    2009-01-01

    Roč. 1216, č. 47 (2009), s. 8371-8378. ISSN 0021-9673 Institutional research plan: CEZ:AV0Z40720504 Keywords : ultra high-performance liquid chromatography * C30 stationary phase * triacylglycerols Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.101, year: 2009

  18. Anisotropic phase-mixing in homogeneous turbulence in a rapidly rotating or in a strongly stratified fluid: An analytical study

    Science.gov (United States)

    Salhi, A.; Cambon, C.

    2007-05-01

    Angular phase mixing in rapidly rotating or in strongly stratified flows is quantified for single-time single-point energy components, using linear theory. In addition to potential energy, turbulent kinetic energy is more easily analyzed in terms of its toroidal and poloidal components, and then in terms of vertical and horizontal components. Since the axial symmetry around the direction n (which bears both the system angular velocity and the mean density gradient) is consistent with basic dynamical equations, the input of initial anisotropy is investigated in the axisymmetric case. A general way to construct axisymmetric initial data is used, with a classical expansion in terms of scalar spherical harmonics for the 3D spectral density of kinetic energy e, and a modified expansion for the polarization anisotropy Z, which reflects the unbalance in terms of poloidal and toroidal energy components. The expansion involves Legendre polynomials of arbitrary order, P2n0(cosθ), (n=0,1,2,…,N0), in which the term [cosθ=(k•n)/∣k∣] characterizes the anisotropy in k-wavespace; two sets of parameters, β2n(e) and β2n(z), separately generate the directional anisotropy and the polarization anisotropy. In the rotating case, the phase mixing results in damping the polarization anisotropy, so that toroidal and poloidal energy components asymptotically equilibrate after transient oscillations. Complete analytical solutions are found in terms of Bessel functions. The envelope of these oscillations decay with time like (ft)-2 (f being the Coriolis parameter), whereas those for the vertical and horizontal components decay like (ft)-3. The long-time limit of the ratio of horizontal component to vertical one depends only on β2(e), which is eventually related to a classical component in structure-based modeling, independently of the degree of the expansion of the initial data. For the stratified case, both the degree of initial anisotropy and the initial unbalance in terms of

  19. A Screening Method for the Identification of Glycosylated Flavonoids and Other Phenolic Compounds Using a Standard Analytical Approach for All Plant Materials

    Science.gov (United States)

    A screening method was developed for the systematic identification of glycosylated flavonoids and other phenolic compounds in plant food materials based on an initial, standard analytical method. This approach applies the same analytical scheme (aqueous methanol extraction, reverse phase liquid chr...

  20. Water structure at aqueous solution surfaces of atmospherically relevant dimethyl sulfoxide and methanesulfonic acid revealed by phase-sensitive sum frequency spectroscopy.

    Science.gov (United States)

    Chen, Xiangke; Allen, Heather C

    2010-11-25

    Interfacial water structures of aqueous dimethyl sulfoxide (DMSO) and methanesulfonic acid (MSA) were studied by Raman, infrared, and conventional and phase-sensitive vibrational sum frequency generation (VSFG) spectroscopies. Through isotopic dilution, we probed bulk water hydrogen bonding strength using the vibrational frequency of dilute OD in H(2)O. As indicated by the frequency shift of the OD frequency, it is shown that DMSO has little influence on the average water hydrogen bonding strength at low concentrations in contrast with an overall weakening effect for MSA. For the water structure at the surface of aqueous solutions, although conventional VSFG spectra suggest only slight structural changes with DMSO and a red shift of hydrogen-bonded water OH frequency, phase-sensitive VSFG reveals more thoroughly structural changes in the presence of both DMSO and MSA. In the case of DMSO, reorientation of interfacial water molecules with their hydrogens pointing up toward the oxygen of the S=O group is observed. For MSA, the interfacial water structure is affected by both the dissociated methanesulfonate anions and the hydronium ions residing at the surface. Both the methanesulfonate anions and the hydronium ions have surface preference; therefore, the electric double layer (EDL) formed at the surface is relatively thin, which leads to partial reorientation of interface water molecules with net orientation of water hydrogens up. Surface DMSO molecules are more effective at reorienting surface water relative to MSA molecules. PMID:21047087

  1. Aqueous phase synthesis of upconversion nanocrystals through layer-by-layer epitaxial growth for in vivo X-ray computed tomography

    KAUST Repository

    Li, Feifei

    2013-05-21

    Lanthanide-doped core-shell upconversion nanocrystals (UCNCs) have tremendous potential for applications in many fields, especially in bio-imaging and medical therapy. As core-shell UCNCs are mostly synthesized in organic solvents, tedious organic-aqueous phase transfer processes are usually needed for their use in bio-applications. Herein, we demonstrate the first example of one-step synthesis of highly luminescent core-shell UCNCs in the "aqueous" phase under mild conditions using innocuous reagents. A microwave-assisted approach allowed for layer-by-layer epitaxial growth of a hydrophilic NaGdF4 shell on NaYF4:Yb, Er cores. During this process, surface defects of the nanocrystals could be gradually passivated by the homogeneous shell deposition, resulting in obvious enhancement in the overall upconversion emission efficiency. In addition, the up-down conversion dual-mode luminescent NaYF4:Yb, Er@NaGdF4:Ce, Ln (Eu, Tb, Sm, Dy) nanocrystals were also synthesized to further validate the successful formation of the core-shell structure. More significantly, based on their superior solubility and stability in water solution, high upconversion efficiency and Gd-doped predominant X-ray absorption, the as-prepared NaYF4:Yb, Er@NaGdF4 core-shell UCNCs exhibited high contrast in in vitro cell imaging and in vivo X-ray computed tomography (CT) imaging, demonstrating great potential as multiplexed luminescent biolabels and CT contrast agents.

  2. Physicochemical characterization of novel aqueous two-phase system: gemini surfactant 12-2-12/NaBr/H2O.

    Science.gov (United States)

    Yue, Ling; He, Zimeng; Zhu, Yunfeng; Shang, Yazhuo; Liu, Honglai

    2015-04-01

    A novel aqueous two-phase system (ATPS) only containing Gemini surfactant ethanediyl-1,2-bis(dodecyldimethylammonium bromide) and an inorganic salt sodium bromide was designed, and the physicochemical properties of the ATPS were investigated systematically. The results have shown that the coexisting two phases, one surfactant-rich and the other salt-rich, are stable and the phase behavior, volume ratio, and extraction efficiency of ATPS are strongly influenced by contents of surfactant and salt. The novel ATPS here investigated have potential application in partitioning and analysis of biomaterials. Compared with other complicated surfactant-based ATPS, the surfactant concentration for the formation of ATPS is much lower, which implies that the studied system is potentially more economical for purification and separation of biomaterials. Meanwhile, the surfactant can be recycled by altering salt concentration in ATPS. Lyotropic liquid crystal was found in the bottom phase besides micelles under different conditions. The salting-out effect may be the driving force of ATPS formation for the studied "living polymer"/salt system. However, the coexistence of micelles with different microstructures is the necessary condition of phase separation. The current studies not only present a new ATPS for partitioning and analysis of biomaterials but also have a great significance on rational use of Gemini surfactants. PMID:25649445

  3. Carbon nanoparticles from corn stalk soot and its novel application as stationary phase of hydrophilic interaction chromatography and per aqueous liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Li Yuanyuan [Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, Lanzhou University, Lanzhou 730000 (China); Key Laboratory of Energy and Chemical Engineering, Ningxia University, Yinchuan 750021 (China); Xu Luan; Chen Tong; Liu Xiaoyan; Xu Zhigang [Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, Lanzhou University, Lanzhou 730000 (China); Zhang Haixia, E-mail: zhanghx@lzu.edu.cn [Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, Lanzhou University, Lanzhou 730000 (China)

    2012-05-13

    Highlights: Black-Right-Pointing-Pointer Carbon nanoparticles (6-18 nm in size) were prepared from corn stalk soot. Black-Right-Pointing-Pointer CNPs-based silica were used as novel chromatography stationary phase. Black-Right-Pointing-Pointer The new phase shows good separation selectivity for polar compounds. Black-Right-Pointing-Pointer The new phase had the similar retention for polar probes in HILIC and PALC modes. Black-Right-Pointing-Pointer In contrast to PALC, under HILIC conditions high efficiencies were achieved. - Abstract: Carbon nanoparticles (CNPs) (6-18 nm in size) were prepared by refluxing corn stalk soot in nitric acid. The obtained acid-oxidized CNPs are soluble in water due to the existence of carboxylic and hydroxyl groups. {sup 13}C NMR measurement shows the CNPs are mainly of sp{sup 2} and sp{sup 3} carbon structure different from CNPs obtained from candle soot and natural gas soot. Furthermore, these CNPs exhibit unique photoluminescence properties. Interestingly, the CNPs might be exploited to immobilize on the surface of porous silica particles as chromatographic stationary phase. The resultant packing material was evaluated by high-performance liquid chromatography, indicating that the new stationary phase could be used in hydrophilic interaction liquid chromatography (HILIC) and per aqueous liquid chromatography (PALC) modes. The separation of five nucleosides, four sulfa compounds and safflower injection was achieved by using the new column in the HILIC and PALC modes, respectively.

  4. Separation of Cd and Ni from Ni-Cd batteries by an environmentally safe methodology employing aqueous two-phase systems

    Energy Technology Data Exchange (ETDEWEB)

    Lacerda, Vania Goncalves; Mageste, Aparecida Barbosa; Santos, Igor Jose Boggione; da Silva, Luis Henrique Mendes; da Silva, Maria do Carmo Hespanhol [Grupo de Quimica Verde Coloidal e Macromolecular, Departamento de Quimica, Centro de Ciencias e Tecnologicas, Universidade Federal de Vicosa, Av. P.H. Rolfs s/n, Campus da UFV, Vicosa, 36570-000 (Brazil)

    2009-09-05

    The separation of Cd and Ni from Ni-Cd batteries using an aqueous two-phase system (ATPS) composed of copolymer L35, Li{sub 2}SO{sub 4} and water is investigated. The extraction behavior of these metals from the bottom phase (BP) to the upper phase (UP) of the ATPS is affected by the amount of added extractant (potassium iodide), tie-line length (TLL), mass ratio between the phases of the ATPS, leaching and dilution factor of the battery samples. Maximum extraction of Cd (99.2 {+-} 3.1)% and Ni (10.6 {+-} 0.4)% is obtained when the batteries are leached with HCl, under the following conditions: 62.53% (w/w) TLL, concentration of KI equal to 50.00 mmol kg{sup -1}, mass ratio of the phases equal to 0.5 and a dilution factor of battery samples of 35. This novel methodology is efficient to separate the metals in question, with the advantage of being environmentally safe, since water is the main constituent of the ATPS, which is prepared with recyclable and biodegradable compounds. (author)

  5. CdTe quantum dots: aqueous phase synthesis, stability studies and protein conjugation for development of biosensors

    Science.gov (United States)

    Borse, Vivek; Sadawana, Mayur; Srivastava, Rohit

    2016-04-01

    Synthesis of quantum dots (QDs) in aqueous medium is advantageous as compared to the organic solvent mediated synthesis, as the aqueous synthesis is less toxic, reagent effective, easily reproducible and importantly, synthesized QDs have biological compatibility. The QDs should be aqueous in nature for use in cell imaging, drug labeling, tracking and delivery. Structural modifications are necessary to enable their use in biosensing application. In this work, mercaptopropionic acid capped cadmium telluride QDs (MPA-CdTe QDs) were synthesized by hydrothermal method and characterized by various techniques. Water and various biochemical buffers were used to study the fluorescence intensity stability of the QDs at different physicochemical conditions. QDs stored in 4° C showed excellent stability of fluorescence intensity values as compared to the samples stored at room temperature. Staphylococcal protein A (SPA) was conjugated with the QDs (SPA-QDs) and characterized using UV and fluorescence spectroscopy, zeta potential, HRTEM, FTIR, and AFM. Blue shift was observed in the fluorescence emission spectra that may be due to reduction in the surface charge as carboxyl groups on QDs were replaced by amino groups of SPA. This SPA conjugated to QDs enables binding of the C-terminal of antibodies on its surface allowing N-terminal binding site remain free to bind with antigenic biomarkers. Thus, the biosensor i.e. antibody bound on SPA-QDs would bind to the antigenic biomarkers in sample and the detection system could be developed. As QDs have better fluorescence properties than organic dyes, this biosensor will provide high sensitivity and quantitative capability in diagnostics.

  6. Overcoming Phase-Transfer Limitations in the Conversion of Lipophilic Oleo Compounds in Aqueous Media-A Thermomorphic Approach.

    Science.gov (United States)

    Gaide, Tom; Dreimann, Jens M; Behr, Arno; Vorholt, Andreas J

    2016-02-01

    A new process concept has been developed for recycling transition-metal catalysts in the synthesis of moderately polar products via aqueous thermomorphic multicomponent solvent systems. This work focuses on the use of "green" solvents (1-butanol and water) in the hydroformylation of the bio-based substrate methyl 10-undecenoate. Following the successful development of a biphasic reaction system on the laboratory scale, the reaction was transferred to a continuously operated miniplant to demonstrate the robustness of this innovative recycling concept for homogenous catalysts. PMID:26822502

  7. Structural and compositional changes of dissolved organic matter upon solid-phase extraction tracked by multiple analytical tools.

    Science.gov (United States)

    Chen, Meilian; Kim, Sunghwan; Park, Jae-Eun; Jung, Heon-Jae; Hur, Jin

    2016-09-01

    Although PPL-based solid-phase extraction (SPE) has been widely used before dissolved organic matter (DOM) analyses via advanced measurements such as ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), much is still unknown about the structural and compositional changes in DOM pool through SPE. In this study, selected DOM from various sources were tested to elucidate the differences between before and after the SPE utilizing multiple analytical tools including fluorescence spectroscopy, FT-ICR-MS, and size exclusion chromatography with organic carbon detector (SEC-OCD). The changes of specific UV absorbance indicated the decrease of aromaticity after the SPE, suggesting a preferential exclusion of aromatic DOM structures, which was also confirmed by the substantial reduction of fluorescent DOM (FDOM). Furthermore, SEC-OCD results exhibited very low recoveries (1-9 %) for the biopolymer fraction, implying that PPL needs to be used cautiously in SPE sorbent materials for treating high molecular weight compounds (i.e., polysaccharides, proteins, and amino sugars). A careful examination via FT-ICR-MS revealed that the formulas lost by the SPE might be all DOM source-dependent. Nevertheless, the dominant missing compound groups were identified to be the tannins group with high O/C ratios (>0.7), lignins/carboxyl-rich alicyclic molecules (CRAM), aliphatics with high H/C >1.5, and heteroatomic formulas, all of which were prevailed by pseudo-analogous molecular formula families with different methylene (-CH2) units. Our findings shed new light on potential changes in the compound composition and the molecular weight of DOM upon the SPE, implying precautions needed for data interpretation. Graphical Abstract Tracking the characteristics of DOM from various origins upon PPL-based SPE utilizing EEMPARAFAC, SEC-OCD, and FT-ICR-MS. PMID:27387996

  8. Nighttime aqueous-phase secondary organic aerosols in Los Angeles and its implication for fine particulate matter composition and oxidative potential

    Science.gov (United States)

    Saffari, Arian; Hasheminassab, Sina; Shafer, Martin M.; Schauer, James J.; Chatila, Talal A.; Sioutas, Constantinos

    2016-05-01

    Recent investigations suggest that aqueous phase oxidation of hydrophilic organic compounds can be a significant source of secondary organic aerosols (SOA) in the atmosphere. Here we investigate the possibility of nighttime aqueous phase formation of SOA in Los Angeles during winter, through examination of trends in fine particulate matter (PM2.5) carbonaceous content during two contrasting seasons. Distinctive winter and summer trends were observed for the diurnal variation of organic carbon (OC) and secondary organic carbon (SOC), with elevated levels during the nighttime in winter, suggesting an enhanced formation of SOA during that period. The nighttime ratio of SOC to OC was positively associated with the relative humidity (RH) at high RH levels (above 70%), which is when the liquid water content of the ambient aerosol would be high and could facilitate dissolution of hydrophilic primary organic compounds into the aqueous phase. Time-integrated collection and analysis of wintertime particles at three time periods of the day (morning, 6:00 a.m.-9:00 a.m.; afternoon, 11:00 a.m.-3:00 p.m.; night, 8:00 p.m.-4:00 a.m.) revealed higher levels of water soluble organic carbon (WSOC) and organic acids during the night and afternoon periods compared to the morning period, indicating that the SOA formation in winter continues throughout the nighttime. Furthermore, diurnal trends in concentrations of semi-volatile organic compounds (SVOCs) from primary emissions showed that partitioning of SVOCs from the gas to the particle phase due to the decreased nighttime temperatures cannot explain the substantial OC and SOC increase at night. The oxidative potential of the collected particles (quantified using a biological macrophage-based reactive oxygen species assay, in addition to the dithiothreitol assay) was comparable during afternoon and nighttime periods, but higher (by at least ∼30%) compared to the morning period, suggesting that SOA formation processes possibly

  9. Extended numerical and analytical model for heat transfer with and without phase change in non ferric powder for thermal spray plasma conditions

    International Nuclear Information System (INIS)

    Splat generation of metal particles on substrates is a very important process for a variety of depositions techniques like plasma thermal spray. In this article an analytical and a numerical model are presented to describe the heating and melting process(heating with phase change), using adequate boundary conditions, global thermal capacity and the Stefan condition at the interface. An analytical dimensionless expression is determined for the temperature distribution as well the position and velocity of the moving liquid-solid interface in terms of Bessel functions. Comparison with the numerical results are carried out.

  10. The challenge of sample-stabilisation in the era of multi-residue analytical methods: a practical guideline for the stabilisation of 46 organic micropollutants in aqueous samples.

    Science.gov (United States)

    Hillebrand, Olav; Musallam, Shadha; Scherer, Laura; Nödler, Karsten; Licha, Tobias

    2013-06-01

    Water sample storage and stabilisation may affect data quality, if samples are managed improperly. In this study three stabilising strategies are evaluated for 46 relevant organic micro-pollutants: addition of the biocides (i) copper sulphate and (ii) sodium azide to water samples directly after sampling with subsequent sample storage as liquid phase and (iii) direct solid phase extraction (SPE), stabilising the samples by reducing the activity of water. River water and treated effluent were chosen as commonly investigated matrices with a high potential of biotransformation activity. Analyses were carried out for sample storage temperatures of 4 and 28°C for water samples stored as liquid phase and for sample storage temperatures of 4, 20 and 40°C for SPE cartridges. Cooling of water samples alone was not sufficient for longer storage times (>24h). While copper sulphate caused detrimental interferences with nitrogen containing heterocyclic compounds, sodium azide proved to be a suitable stabilising agent. The best results could be obtained for SPE cartridges stored cool. Recommendations for samples preservation are provided. PMID:23562683

  11. Analytical solution for transient partitioning and reaction of a condensing vapor species in a droplet

    OpenAIRE

    Liu, Albert Tianxiang; Zaveri, Rahul A.; Seinfeld, John H.

    2014-01-01

    We present the exact analytical solution of the transient equation of gas-phase diffusion of a condensing vapor to, and diffusion and reaction in, an aqueous droplet. Droplet-phase reaction is represented by first-order chemistry. The solution facilitates study of the dynamic nature of the vapor uptake process as a function of droplet size, Henry's law coefficient, and first-order reaction rate constant for conversion in the droplet phase.

  12. Aqueous phase Ag nanoparticles with controlled shapes fabricated by a modified nanosphere lithography and their optical properties

    International Nuclear Information System (INIS)

    We have developed a modified nanosphere lithography (NSL) process to fabricate surface-confined Ag nanoparticles (NPs) with controlled shapes. NPs with different shapes, such as triangular, quadrilateral, pentagon or trapezoidal with rounded tips or edges, can be fabricated by this process. These Ag NPs can be dislodged into water forming NPs in an aqueous environment. The developed process results in better NP shape retaining than those obtained using the routine NSL process. The UV-vis absorption of the surface-confined Ag NPs show distinct blue shift and reduced intensity after surface modification. The NPs produced by the modified NSL and dislodged in water have significantly less density of debris as observed by transmission electron microscopy and UV-vis absorption spectrum.

  13. Peptide-lanthanide cation equilibria in aqueous phase. I. Bound shifts for L-carnosine-praseodymium complexes

    Science.gov (United States)

    Mossoyan, J.; Asso, M.; Benlian, D.

    L-Carnosine complexes of Pr 3+ were characterized in aqueous solution by 1H NMR and potentiometric titration. A rigorous treatment of chemical shifts and pH variation data with lanthanide concentration is presented. Two different forms of the peptide ligand, forming simultaneously two complexes, were taken into account. At low pH values the cation is only coordinated at the carboxylate site of the ligand in a weak complex ( β2 = 6) whereas in neutral solution a stronger complex ( β1 = 37) is present as a consequence of the deprotonation of the imidazole ring. The computation of induced bound shifts † 2 and Δ1 for resonating nuclei of the peptide in both forms yields consistent figures. These provide the experimental basis for a conformational model which is usually not obtainable for labile complexes with low stability constants.

  14. Partition of proteins in aqueous two-phase systems based on Cashew-nut tree gum and poly(ethylene glycol

    Directory of Open Access Journals (Sweden)

    Leonie Asfora Sarubbo

    2004-09-01

    Full Text Available The partitioning of two proteins, bovine serum albumin (BSA and trypsin was studied in an aqueous poly(ethylene glycol(PEG- Cashew-nut tree gum system. The phase diagram was provided for Cashew-nut tree gum and PEG molecular weight of 1500 at two different temperatures. The influence of several parameters including concentrations of polymers, pH, salt addition and temperature on the partitioning of these proteins were investigated.. The results of this research demonstrated the importance of the protein characteristics for partitioning in aqueous biphasic system.A partição de duas proteínas, albumina de soro bovino (BSA e tripsina foi estudada no sistema bifásico aquoso Polietileno glicol(PEG - Goma do cajueiro. O diagrama de fases foi estabelecido para a Goma do Cajueiro e para PEG de peso molecular 1500 em duas diferentes temperaturas. A influência de vários parâmetros na partição destas proteínas, incluindo concentração dos polímeros, pH, adição de sal e temperatura foi investigada. Os resultados desta pesquisa demonstraram a importância das características da proteína na partição em sistemas bifásicos aquosos.

  15. Multi-residue analysis of pharmaceuticals in aqueous environmental samples by online solid-phase extraction-ultra-high-performance liquid chromatography-tandem mass spectrometry: optimisation and matrix effects reduction by quick, easy, cheap, effective, rugged and safe extraction.

    Science.gov (United States)

    Bourdat-Deschamps, Marjolaine; Leang, Sokha; Bernet, Nathalie; Daudin, Jean-Jacques; Nélieu, Sylvie

    2014-07-01

    The aim of this study was to develop and optimise an analytical method for the quantification of a bactericide and 13 pharmaceutical products, including 8 antibiotics (fluoroquinolones, tetracyclines, sulfonamides, macrolide), in various aqueous environmental samples: soil water and aqueous fractions of pig slurry, digested pig slurry and sewage sludge. The analysis was performed by online solid-phase extraction coupled to ultra-high performance liquid chromatography with tandem mass spectrometry (online SPE-UHPLC-MS-MS). The main challenge was to minimize the matrix effects observed in mass spectrometry, mostly due to ion suppression. They depended on the dissolved organic carbon (DOC) content and its origin, and ranged between -22% and +20% and between -38% and -93% of the signal obtained without matrix, in soil water and slurry supernatant, respectively. The very variable levels of these matrix effects suggested DOC content cut-offs above which sample purification was required. These cut-offs depended on compounds, with concentrations ranging from 30 to 290mgC/L for antibiotics (except tylosine) up to 600-6400mgC/L for the most apolar compounds. A modified Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) extraction procedure was therefore optimised using an experimental design methodology, in order to purify samples with high DOC contents. Its performance led to a compromise, allowing fluoroquinolone and tetracycline analysis. The QuEChERS extraction salts consisted therefore of sodium acetate, sodium sulfate instead of magnesium sulfate, and sodium ethylenediaminetetraacetate (EDTA) as a ligand of divalent cations. The modified QuEChERS procedure employed for the extraction of pharmaceuticals in slurry and digested slurry liquid phases reduced the matrix effects for almost all the compounds, with extraction recoveries generally above 75%. The performance characteristics of the method were evaluated in terms of linearity, intra-day and inter

  16. Determination of Vitamin B6 by Fluorimetry after Aqueous Two-Phase Extraction Based on Ionic Liquid%离子液体双水相萃取荧光法测定维生素B6

    Institute of Scientific and Technical Information of China (English)

    谢秀娟; 张振新

    2011-01-01

    Based on the fact that water-miscible sol vent, such as ionic liquid, can be used to form aqueous two-phase system for extraction of analytes in the presence of salts, ionic liquid-salt system of ionic liquid( [Bmim]Br )and(NH4)2SO4 was developed for the determination of trace vitamin B6 coupled with fluorimetry after aqueous two-phase extraction. Factors that affect the extraction efficiencies of vitamin B6 including pH, the amount of extractant and extraction time were well studied. Under the optimal conditions, I. E. , λex/λem = 342/418 nm,pH = 8. 69, 1. 3 mL ionic liquid, 2. 8 g ammonium sulfate and 3 min of extraction, the extraction method presented a linear range of 1. 6×10-7~l. 04×10-5 g/L with a detection limit of 4. 8 × 10-7 g/L.%基于离子液体在盐的作用下能够形成双水相,用于目标物质的萃取,提出了离子液体-硫酸铵双水相萃取、荧光法测定痕量维生素B6的新方法.实验探讨了影响维生素B6萃取率的主要因素,如酸度、萃取剂的用量、时间等.在最适条件下,即λex/λem=342/418 nm,pH=8.69,离子液体和硫酸铵的用量分别为1.3mL、2.8g,萃取3 min时,体系测定维生素B6的线性范围为1.6×10-7~1.04×10-5 g/L,检出限为4.8×10-7 g/L.

  17. Phase diagrams for (liquid + liquid) and (liquid + solid) equilibrium of aqueous two-phase system containing {polyvinylpyrrolidone 3500 (PVP3500) + sodium sulfite (Na2SO3) + water} at different temperatures

    International Nuclear Information System (INIS)

    Highlights: • LLE of (polyvinylpyrrolidone + sodium sulfite + water) was studied. • The complete phase diagram for PVP3500 + Na2SO3 + H2O was determined at T = 298.15 K. • Binodal data were correlated with two empirical equations. • Tie-lines were fitted to several models including extended NRTL and modified NRTL. • The entropy is driving force for aqueous two-phase formation. - Abstract: The (liquid + liquid) equilibrium (LLE) for the {polyvinylpyrrolidone (PVP3500) + Na2SO3 + H2O} system has been determined experimentally at T = (298.15, 308.15 and 318.15) K. The (liquid + liquid + solid) equilibrium (LLSE) and complete phase diagram of this system were also obtained at T = 298.15 K. The effect of temperature on the binodal curves and the tie-lines for the investigated aqueous two-phase system (ATPS) have been studied. The Merchuk equation and an empirical equation that we proposed in our previous work were used for reproducing the experimental binodal results, and their three fitting parameters were obtained with the temperature dependence expressed in the linear form with (T − T0) K as a variable. Furthermore, the Othmer–Tobias and Bancroft, a temperature dependent Setschenow-type equation and osmotic virial model, the segment-based local composition models (i.e. the extended NRTL (E-NRTL) and modified NRTL (M-NRTL)) were used for the correlation of the (liquid + liquid) phase behavior of the studied system. Also, we estimated plait point, slope and the length of tie-lines at T = (298.15, 308.15 and 318.15) K

  18. Study of different HILIC, mixed-mode, and other aqueous normal-phase approaches for the liquid chromatography/mass spectrometry-based determination of challenging polar pesticides.

    Science.gov (United States)

    Vass, Andrea; Robles-Molina, José; Pérez-Ortega, Patricia; Gilbert-López, Bienvenida; Dernovics, Mihaly; Molina-Díaz, Antonio; García-Reyes, Juan F

    2016-07-01

    The aim of the study was to evaluate the performance of different chromatographic approaches for the liquid chromatography/mass spectrometry (LC-MS(/MS)) determination of 24 highly polar pesticides. The studied compounds, which are in most cases unsuitable for conventional LC-MS(/MS) multiresidue methods were tested with nine different chromatographic conditions, including two different hydrophilic interaction liquid chromatography (HILIC) columns, two zwitterionic-type mixed-mode columns, three normal-phase columns operated in HILIC-mode (bare silica and two silica-based chemically bonded columns (cyano and amino)), and two standard reversed-phase C18 columns. Different sets of chromatographic parameters in positive (for 17 analytes) and negative ionization modes (for nine analytes) were examined. In order to compare the different approaches, a semi-quantitative classification was proposed, calculated as the percentage of an empirical performance value, which consisted of three main features: (i) capacity factor (k) to characterize analyte separation from the void, (ii) relative response factor, and (iii) peak shape based on analytes' peak width. While no single method was able to provide appropriate detection of all the 24 studied species in a single run, the best suited approach for the compounds ionized in positive mode was based on a UHPLC HILIC column with 1.8 μm particle size, providing appropriate results for 22 out of the 24 species tested. In contrast, the detection of glyphosate and aminomethylphosphonic acid could only be achieved with a zwitterionic-type mixed-mode column, which proved to be suitable only for the pesticides detected in negative ion mode. Finally, the selected approach (UHPLC HILIC) was found to be useful for the determination of multiple pesticides in oranges using HILIC-ESI-MS/MS, with limits of quantitation in the low microgram per kilogram in most cases. Graphical Abstract HILIC improves separation of multiclass polar pesticides

  19. Simultaneous determination of benzothiazoles, benzotriazoles and benzosulfonamides by solid phase microextraction-gas chromatography-triple quadrupole mass spectrometry in environmental aqueous matrices and human urine.

    Science.gov (United States)

    Naccarato, Attilio; Gionfriddo, Emanuela; Sindona, Giovanni; Tagarelli, Antonio

    2014-04-18

    This work proposes a new approach for the simultaneous determination of benzothiazoles, benzotriazoles and benzosulfonamides in different environmental matrices and human urine, using solid-phase microextraction coupled with gas-chromatography-triple quadrupole mass spectrometry (SPME-GC-QqQMS). The analytes object of this investigation have been classified as toxic to aquatic organisms and their presence in human urine was reported to occur as result of human exposure to contaminated environment. In this work many of the challenges related to the chemical diversity and polarity of the analytes selected were overcame conducting a multivariate optimization of the working conditions by using the approach of "Experimental design". Tests performed to assess the performances of five SPME coatings in direct immersion mode revealed the polyacrylate coating to be the most suitable for the extraction of the probe analytes. A central composite design (CCD) was employed to determine the optimal conditions for four factors affecting the solid-phase microextraction process: extraction time, extraction temperature, pH and percentage of sodium chloride. The optimal working condition determined by using Derringer's desirability function were 40min as extraction time, pH 7.1 and 6.0% of NaCl. Since the extraction temperature do not significantly affects the responses for all the analytes considered, analyses were performed at room temperature. A careful evaluation of the matrix effect for all the matrices tested was carried out. The results obtained showed that the proposed method did not significantly influenced by matrix effects in most of the cases tested, and thus allows the use of simplified calibration procedure. Satisfactory values of accuracy and precision were also obtained for all the matrices considered. PMID:24636758

  20. Phase transition of silver nanoparticles from aqueous solution to chloroform with the help of inclusion complexes of p-sulfonated calix[4]arene and alkanethiol molecules and its application in the size sorting of nanoparticles

    International Nuclear Information System (INIS)

    Silver nanoparticles were synthesized in aqueous solution and capped with an inclusion complex of octadecanethiol (ODT) and p-sulfonated calix[4]arene (pSC4). By vigorous shaking of a biphasic mixture of the pSC4-threaded ODT-stabilized silver hydrosol and chloroform, the phase transition of the silver nanoparticles could be observed in the course of the transition of colour from the aqueous phase to the organic phase. The procedure of phase transition was independently verified by UV-vis spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, and 1H nuclear magnetic resonance (NMR). In shaking the biphasic mixture, it was believed that pSC4 molecules were desorbed from the inclusion complex and the protective layer of silver nanoparticles shifted from hydrophilic to hydrophobic, which drove the phase transition of silver nanoparticles from aqueous solution into chloroform. More interestingly, the efficiency in the phase transition of aqueous silver nanoparticles rigidly depended on their sizes, which maybe used in the size sorting of nanoparticles