WorldWideScience

Sample records for polar solvent typically

  1. Photophysics of Curcumin excited state in toluene-polar solvent mixtures: Role of H-bonding properties of the polar solvent

    Energy Technology Data Exchange (ETDEWEB)

    Saini, R.K.; Das, K., E-mail: kaustuv@rrcat.gov.in

    2014-01-15

    Excited state dynamics of Curcumin in binary solvent mixtures of toluene and polar H-bonding solvents were compared by using an instrument endowed with 40 ps time resolution. The solvation time constant of Curcumin increases significantly (and can therefore be measured) in polar solvents which have, either, both H-bond donating and accepting ability, or, only H-bond donating ability. These results suggest that the rate limiting step in the excited state dynamics of the pigment might be the formation and reorganization of the intermolecular H-bonding between the keto group of the pigment and the H-bond donating moieties of the polar solvent. -- Highlights: • Excited state dynamics of Curcumin in a binary solvent mixture of toluene and three polar H-bonding solvents were compared. • The solvation time constant increases significantly with polar solvents having, H-bond donating and accepting, or, H-bond donating ability. • Observed results suggest that H-bonding property of polar solvent plays an important role in the excited state dynamics. • Intermolecular H-bonding between the keto group of the pigment and polar solvent may be the rate limiting step.

  2. Photophysics of Curcumin excited state in toluene-polar solvent mixtures: Role of H-bonding properties of the polar solvent

    International Nuclear Information System (INIS)

    Saini, R.K.; Das, K.

    2014-01-01

    Excited state dynamics of Curcumin in binary solvent mixtures of toluene and polar H-bonding solvents were compared by using an instrument endowed with 40 ps time resolution. The solvation time constant of Curcumin increases significantly (and can therefore be measured) in polar solvents which have, either, both H-bond donating and accepting ability, or, only H-bond donating ability. These results suggest that the rate limiting step in the excited state dynamics of the pigment might be the formation and reorganization of the intermolecular H-bonding between the keto group of the pigment and the H-bond donating moieties of the polar solvent. -- Highlights: • Excited state dynamics of Curcumin in a binary solvent mixture of toluene and three polar H-bonding solvents were compared. • The solvation time constant increases significantly with polar solvents having, H-bond donating and accepting, or, H-bond donating ability. • Observed results suggest that H-bonding property of polar solvent plays an important role in the excited state dynamics. • Intermolecular H-bonding between the keto group of the pigment and polar solvent may be the rate limiting step

  3. Dispersing surface-modified imogolite nanotubes in polar and non-polar solvents

    Science.gov (United States)

    Li, Ming; Brant, Jonathan A.

    2018-02-01

    Furthering the development of nanocomposite structures, namely membranes for water treatment applications, requires that methods be developed to ensure nanoparticle dispersion in polar and non-polar solvents, as both are widely used in associated synthesis techniques. Here, we report on a two-step method to graft polyvinylpyrrolidone (PVP), and a one-step method for octadecylphosphonic acid (OPA), onto the outer surfaces of imogolite nanotubes. The goal of these approaches was to improve and maintain nanotube dispersion in polymer compatible polar and non-polar solvents. The PVP coating modified the imogolite surface charge from positive to weakly negative at pH ≤ 9; the OPA made it weakly positive at acidic pH values to negative at pH ≥ 7. The PVP surface coating stabilized the nanotubes through steric hindrance in polar protic, dipolar aprotic, and chloroform. In difference to the PVP, the OPA surface coating allowed the nanotubes to be dispersed in n-hexane and chloroform, but not in the polar solvents. The lack of miscibility in the polar solvents, as well as the better dispersion in n-hexane, was attributed to the stronger hydrophobicity of the OPA polymer relative to the PVP. [Figure not available: see fulltext.

  4. Polar and low polar solvents media effect on dipole moments of some diazo Sudan dyes

    Science.gov (United States)

    Zakerhamidi, M. S.; Golghasemi Sorkhabi, Sh.; Shamkhali, A. N.

    2014-06-01

    Absorption and fluorescence spectra of three Sudan dyes (SudanIII, SudanIV and Sudan black B) were recorded in various solvents with different polarity in the range of 300-800 nm, at room temperature. The solvatochromic method was used to investigate dipole moments of these dyes in ground and excited states, in different media. The solvatochromic behavior of these substances and their solvent-solute interactions were analyzed via solvent polarity parameters. Obtained results express the effects of solvation on tautomerism and molecular configuration (geometry) of Sudan dyes in solvent media with different polarity. Furthermore, analyze of solvent-solute interactions and value of ground and excited states dipole moments suggests different forms of resonance structures for Sudan dyes in polar and low-polar solvents.

  5. Effect of solvent polarity and temperature on the spectral and thermodynamic properties of exciplexes of 1-cyanonaphthalene with hexamethylbenzene in organic solvents

    International Nuclear Information System (INIS)

    Asim, Sadia; Mansha, Asim; Grampp, Günter; Landgraf, Stephan; Zahid, Muhammad; Bhatti, Ijaz Ahmad

    2014-01-01

    Study of the effect of solvent polarity and temperature is done on the exciplex emission spectra of 1-cyanonaphthalene with hexamethylbenzene. Exciplex system is studied in the range of partially polar solvents and in solvent mixture of propyl acetate and butyronitrile. The unique feature of this solvent mixture is that only the solvent polarity changes (6.0≤ε s ≤24.7) with the change in the mole fraction of solvents whereas the solvent viscosity and refractive index remains unaffected. Thermodynamic properties are calculated according to the models developed by Weller and Kuzmin. Fluorescence lifetimes for both the fluorophore as well as the exciplex are evaluated in all used solvents. Exciplex energetics as a function of solvent polarity and temperature are also discussed. Kuzmin model of self-consistent polarization is used for the explanation of the exciplex emission spectra. The effects of solvent polarity and temperature on energy of zero–zero transitions (hv 0 / ), Huang–Rhys factor (S), Gauss broadening of vibronic level (σ) and the dominant high-frequency vibration (hν ν ) are investigated. The strong dependence of exciplex stability and energetics upon the solvent polarity and temperature are observed. Full charge transfer exciplexes were observed in solvents of all polarities and stronger exciplex with large emission intensities were found in solvents of low polarities but with the increase in solvent polarity the exciplex becomes weak and they dissociate fastly into radical ion pairs. The kinetic model of Kuzmin was observed to reduce into the Weller kinetic model for this exciplex system with ∆G ET = −0.22 eV and the spectral shift, h∆ν>0.2 eV. - Highlights: • Exciplex formed as a result of mixing of charge transfer and locally excited states. • Effect of solvents polarity and temperature on the exciplex stability and thermodynamics. • Solvent polarity will decide the formation of contact radical ion pair or solvent separated

  6. Effect of solvent polarity and temperature on the spectral and thermodynamic properties of exciplexes of 1-cyanonaphthalene with hexamethylbenzene in organic solvents

    Energy Technology Data Exchange (ETDEWEB)

    Asim, Sadia [Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremaryrgasse 9, A-8010 Graz (Austria); Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad (Pakistan); Mansha, Asim [Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremaryrgasse 9, A-8010 Graz (Austria); Department of Chemistry, Government College University, Faisalabad (Pakistan); Grampp, Günter, E-mail: grampp@tugraz.at [Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremaryrgasse 9, A-8010 Graz (Austria); Landgraf, Stephan [Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremaryrgasse 9, A-8010 Graz (Austria); Zahid, Muhammad [Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremaryrgasse 9, A-8010 Graz (Austria); Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad (Pakistan); Bhatti, Ijaz Ahmad [Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad (Pakistan)

    2014-09-15

    Study of the effect of solvent polarity and temperature is done on the exciplex emission spectra of 1-cyanonaphthalene with hexamethylbenzene. Exciplex system is studied in the range of partially polar solvents and in solvent mixture of propyl acetate and butyronitrile. The unique feature of this solvent mixture is that only the solvent polarity changes (6.0≤ε{sub s}≤24.7) with the change in the mole fraction of solvents whereas the solvent viscosity and refractive index remains unaffected. Thermodynamic properties are calculated according to the models developed by Weller and Kuzmin. Fluorescence lifetimes for both the fluorophore as well as the exciplex are evaluated in all used solvents. Exciplex energetics as a function of solvent polarity and temperature are also discussed. Kuzmin model of self-consistent polarization is used for the explanation of the exciplex emission spectra. The effects of solvent polarity and temperature on energy of zero–zero transitions (hv{sub 0}{sup /}), Huang–Rhys factor (S), Gauss broadening of vibronic level (σ) and the dominant high-frequency vibration (hν{sub ν}) are investigated. The strong dependence of exciplex stability and energetics upon the solvent polarity and temperature are observed. Full charge transfer exciplexes were observed in solvents of all polarities and stronger exciplex with large emission intensities were found in solvents of low polarities but with the increase in solvent polarity the exciplex becomes weak and they dissociate fastly into radical ion pairs. The kinetic model of Kuzmin was observed to reduce into the Weller kinetic model for this exciplex system with ∆G{sub ET} = −0.22 eV and the spectral shift, h∆ν>0.2 eV. - Highlights: • Exciplex formed as a result of mixing of charge transfer and locally excited states. • Effect of solvents polarity and temperature on the exciplex stability and thermodynamics. • Solvent polarity will decide the formation of contact radical ion pair

  7. Dispersions of Goethite Nanorods in Aprotic Polar Solvents

    Directory of Open Access Journals (Sweden)

    Delphine Coursault

    2017-10-01

    Full Text Available Colloidal suspensions of anisotropic nanoparticles can spontaneously self-organize in liquid-crystalline phases beyond some concentration threshold. These phases often respond to electric and magnetic fields. At lower concentrations, usual isotropic liquids are observed but they can display very strong Kerr and Cotton-Mouton effects (i.e., field-induced particle orientation. For many examples of these colloidal suspensions, the solvent is water, which hinders most electro-optic applications. Here, for goethite (α-FeOOH nanorod dispersions, we show that water can be replaced by polar aprotic solvents, such as N-methyl-2-pyrrolidone (NMP and dimethylsulfoxide (DMSO, without loss of colloidal stability. By polarized-light microscopy, small-angle X-ray scattering and electro-optic measurements, we found that the nematic phase, with its field-response properties, is retained. Moreover, a strong Kerr effect was also observed with isotropic goethite suspensions in these polar aprotic solvents. Furthermore, we found no significant difference in the behavior of both the nematic and isotropic phases between the aqueous and non-aqueous dispersions. Our work shows that goethite nanorod suspensions in polar aprotic solvents, suitable for electro-optic applications, can easily be produced and that they keep all their outstanding properties. It also suggests that this solvent replacement method could be extended to the aqueous colloidal suspensions of other kinds of charged anisotropic nanoparticles.

  8. The spectral properties of (--epigallocatechin 3-O-gallate (EGCG fluorescence in different solvents: dependence on solvent polarity.

    Directory of Open Access Journals (Sweden)

    Vladislav Snitsarev

    Full Text Available (--Epigallocatechin 3-O-gallate (EGCG a molecule found in green tea and known for a plethora of bioactive properties is an inhibitor of heat shock protein 90 (HSP90, a protein of interest as a target for cancer and neuroprotection. Determination of the spectral properties of EGCG fluorescence in environments similar to those of binding sites found in proteins provides an important tool to directly study protein-EGCG interactions. The goal of this study is to examine the spectral properties of EGCG fluorescence in an aqueous buffer (AB at pH=7.0, acetonitrile (AN (a polar aprotic solvent, dimethylsulfoxide (DMSO (a polar aprotic solvent, and ethanol (EtOH (a polar protic solvent. We demonstrate that EGCG is a highly fluorescent molecule when excited at approximately 275 nm with emission maxima between 350 and 400 nm depending on solvent. Another smaller excitation peak was found when EGCG is excited at approximately 235 nm with maximum emission between 340 and 400 nm. We found that the fluorescence intensity (FI of EGCG in AB at pH=7.0 is significantly quenched, and that it is about 85 times higher in an aprotic solvent DMSO. The Stokes shifts of EGCG fluorescence were determined by solvent polarity. In addition, while the emission maxima of EGCG fluorescence in AB, DMSO, and EtOH follow the Lippert-Mataga equation, its fluorescence in AN points to non-specific solvent effects on EGCG fluorescence. We conclude that significant solvent-dependent changes in both fluorescence intensity and fluorescence emission shifts can be effectively used to distinguish EGCG in aqueous solutions from EGCG in environments of different polarity, and, thus, can be used to study specific EGCG binding to protein binding sites where the environment is often different from aqueous in terms of polarity.

  9. Plasma-polymerized films providing selective affinity to the polarity of vaporized organic solvents

    International Nuclear Information System (INIS)

    Akimoto, Takuo; Ikeshita, Yusuke; Terashima, Ryo; Karube, Isao

    2009-01-01

    Plasma-polymerized films (PPFs) were fabricated as recognition membranes for a vapor-sensing device, and their affinity to vaporized organic solvents was evaluated with surface plasmon resonance. The affinity we intended to create is the selective sorption of the vaporized organic solvents depending on their polarity. For this purpose, acetonitrile, ethylenediamine (EDA), styrene, hexamethyldisiloxane (HMDSO), and hexamethyldisilazane were used to fabricate PPFs. Vaporized methanol, ethanol, and 1-propanol were used as high-polar solvents to be analyzed. Hexane, toluene, and p-xylene were used as low-polar solvents. As a result, the HMDSO-PPF with 97.3 o of contact angle was found to provide affinity to the low-polar solvents. In contrast, the EDA-PPF with 7.1 o of contact angle provided affinity to the high-polar solvents. Observations of the surface morphology of the HMDSO- and EDA-PPFs with a scanning electron microscope revealed that they are composed of nano-scale islands.

  10. Directed Assembly of Janus Cylinders by Controlling the Solvent Polarity.

    Science.gov (United States)

    Kim, Jongmin; Choi, Chang-Hyung; Yeom, Su-Jin; Eom, Naye; Kang, Kyoung-Ku; Lee, Chang-Soo

    2017-08-01

    This study demonstrates the possibility of controlling the directed self-assembly of microsized Janus cylinders by changing the solvent polarity of the assembly media. Experimental results are analyzed and theoretical calculations of the free energy of adhesion (ΔG ad ) are performed to elucidate the underlying basic principles and investigate the effects of the solvent on the self-assembled structures. This approach will pave a predictive route for controlling the structures of assembly depending on the solvent polarity. In particular, we find that a binary solvent system with precisely controlled polarity induces directional assembly of the microsized Janus cylinders. Thus, the formation of two-dimensional (2D) and three-dimensional (3D) assembled clusters can be reliably tuned by controlling the numbers of constituent Janus cylinders in a binary solvent system. Finally, this approach is expanded to stepwise assembly, which forms unique microstructures via secondary growth of primary seed clusters formed by the Janus cylinders. We envision that this investigation is highly promising for the construction of desired superstructures using a wide variety of polymeric Janus microparticles with chemical and physical multicompartments.

  11. Organic high ionic strength aqueous two-phase solvent system series for separation of ultra-polar compounds by spiral high-speed counter-current chromatography

    Science.gov (United States)

    Zeng, Yun; Liu, Gang; Ma, Ying; Chen, Xiaoyuan; Ito, Yoichiro

    2011-01-01

    Existing two-phase solvent systems for high-speed countercurrent chromatography cover the separation of hydrophobic to moderately polar compounds, but often fail to provide suitable partition coefficient values for highly polar compounds such as sulfonic acids, catecholamines and zwitter ions. The present paper introduces a new solvent series which can be applied for the separation of these polar compounds. It is composed of 1-butanol, ethanol, saturated ammonium sulfate and water at various volume ratios and consists of a series of 10 steps which are arranged according to the polarity of the solvent system so that the two-phase solvent system with suitable K values for the target compound(s) can be found in a few steps. Each solvent system gives proper volume ratio and high density difference between the two phases to provide a satisfactory level of retention of the stationary phase in the spiral column assembly. The method is validated by partition coefficient measurement of four typical polar compounds including methyl green (basic dye), tartrazine (sulfonic acid), tyrosine (zwitter ion) and epinephrine (a catecholamine), all of which show low partition coefficient values in the polar 1-butanol-water system. The capability of the method is demonstrated by separation of three catecholamines. PMID:22033108

  12. Solvent polarity effects on supramolecular chirality of a polyfluorene-thiophene copolymer.

    Science.gov (United States)

    Hirahara, Takashi; Yoshizawa-Fujita, Masahiro; Takeoka, Yuko; Rikukawa, Masahiro

    2018-06-01

    This study demonstrates the supramolecular chirality control of a conjugated polymer via solvent polarity. We designed and synthesized a chiral polyfluorene-thiophene copolymer having two different chiral side chains at the 9-position of the fluorene unit. Chiral cyclic and alkyl ethers with different polarities were selected as the chiral side chains. The sign of the circular dichroism spectra in the visible wavelength region was affected by the solvent system, resulting from the change of supramolecular structure. The estimation of the solubility parameter revealed that the solubility difference of the side chains contributed to the change of the circular dichroism sign, which was also observed in spin-coated films prepared from good solvents having different polarities. © 2018 Wiley Periodicals, Inc.

  13. Effects of polar protic solvents on dual emissions of 3 ...

    Indian Academy of Sciences (India)

    TECS

    Figure 1. Scheme of the ESIPT reaction of 3-hydroxy- chromone, 1. Chart 1. Chemical structures of the studied ... Materials and methods. Absorption and ... 85. Table 1. Spectroscopic properties of 3HC dyes in different polar solvents.a. Solvent.

  14. Anion-π aromatic neutral tweezers complexes: are they stable in polar solvents?

    Science.gov (United States)

    Sánchez-Lozano, Marta; Otero, Nicolás; Hermida-Ramón, Jose M; Estévez, Carlos M; Mandado, Marcos

    2011-03-17

    The impact of the solvent environment on the stabilization of the complexes formed by fluorine (T-F) and cyanide (T-CN) substituted tweezers with halide anions has been investigated theoretically. The study was carried out using computational methodologies based on density functional theory (DFT) and symmetry adapted perturbation theory (SAPT). Interaction energies were obtained at the M05-2X/6-31+G* level. The obtained results show a large stability of the complexes in solvents with large dielectric constant and prove the suitability of these molecular tweezers as potential hosts for anion recognition in solution. A detailed analysis of the effects of the solvent on the electron withdrawing ability of the substituents and its influence on the complex stability has been performed. In particular, the interaction energy in solution was split up into intermonomer and solvent-complex terms. In turn, the intermonomer interaction energy was partitioned into electrostatic, exchange, and polarization terms. Polar resonance structures in T-CN complexes are favored by polar solvents, giving rise to a stabilization of the intermonomer interaction, the opposite is found for T-F complexes. The solvent-complex energy increases with the polarity of the solvent in T-CN complexes, nonetheless the energy reaches a maximum and then decreases slowly in T-F complexes. An electron density analysis was also performed before and after complexation, providing an explanation to the trends followed by the interaction energies and their different components in solution.

  15. A comparison of geochemical features of extracts from coal-seams source rocks with different polarity solvents

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jianping; Deng, Chunping; Wang, Huitong

    2009-02-15

    There exists a great difference in group-type fractions and biomarker distributions of chloroform extracts from coals and coal-seams oils, which makes the source identification of coal-seams oils in sedimentary basins rather difficult. The experiment, in which four different polarity solvents, n-hexane, benzene, dichloromethane and chloroform, were used to extract 9 coal-seams source rocks and 3 typical lacustrine source rocks, showed that the yield of extracts increased gradually with increasing solvent polarity. The distribution features of their n-alkanes, isoprenoids and sterane and terpane biomarkers remained, in general, similar, showing no distinct enrichment or depletion for a certain fraction by any solvent. The compositional analysis on n-hexane and chloroform extracts showed that the absolute amount (concentration) of biomarkers was relatively low for the n-hexane extract but comparatively high for the chloroform extract, this difference became great among coal-seams source rocks but small among lacustrine mudstones. The statistical analysis on the relative amount of the 18 major biomarkers in n-hexane and chloroform extracts from 10 source rock samples showed that extracts with a proportional error for the same biomarker of less than 5% (including the analytical error) accounted for 84% while those with a proportional error over 10% amounted to below 5%. This suggested that the outcome of oil-source correlation made by these biomarkers will be independent of variations in amounts of saturates and biomarkers arising from solvent polarity. Therefore, biomarkers obtained from organic-rich source rocks including coals by the extraction with the commonly used chloroform solvent can be applied for the oilsource correlation of coal-seams petroliferous basins.

  16. Simultaneously 'pushing' and 'pulling' graphene oxide into low-polar solvents through a designed interface.

    Science.gov (United States)

    Liu, Zhen; Liu, Jingquan; Wang, Yichao; Razal, Joselito M; Francis, Paul S; Biggs, Mark J; Barrow, Colin J; Yang, Wenrong

    2018-08-03

    Dispersing graphene oxide (GO) in low-polar solvents can realize a perfect self-assembly with functional molecules and application in removal of organic impurities that only dissolve in low-polar solvents. The surface chemistry of GO plays an important role in its dispersity in these solvents. The direct transfer of hydrophilic GO into low-polar solvents, however, has remained an experimental challenge. In this study, we design an interface to transfer GO by simultaneously 'pushing and pulling' the nanosheets into low-polar solvents. Our approach is outstanding due to the ability to obtain monolayers of chemically reduced GO (CRGO) with designed surface properties in the organic phase. Using the transferred GO or CRGO dispersions, we have fabricated GO/fullerene nanocomposites and assessed the ability of CRGOs for dye adsorption. We hope our work can provide a universal approach for the phase transfer of other nanomaterials.

  17. Characterization of microenvironment polarity and solvent accessibility of polysilsesquioxane xerogels by the fluorescent probe technique

    Energy Technology Data Exchange (ETDEWEB)

    Shea, K.J.; Zhu, H.D. [Univ., of California, Irvine, CA (United States). Dept. of Chemistry; Loy, D.A. [Sandia National Labs., Albuquerque, NM (United States)

    1995-05-01

    Poly (1, 4 bis(triethoxysilyl)benzene) (PTESB), a representative of a new type of organic-inorganic hybrid polysilsesquioxane material, was characterized by fluorescence spectroscopy for both microenvironmental polarity and solvent accessibility. A dansyl fluorescent molecule was incorporated into the bulk as well as onto the surface of both PTESB and silica materials. Information about the microenvironment polarity and accessibility of PTESB to various organic solvents was determined and compared to that of silica gel. This study found that both the bulk and surface of PTESB are less polar than that of the silica material. The silica material is accessible to polar solvents and water, while YMB is accessible to polar solvents but not to water. The hydrophobicity of PTESB differentiates these new materials from silica gel.

  18. The Role of Solvent Polarity on Low-Temperature Methanol Synthesis Catalyzed by Cu Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ahoba-Sam, Christian [Department of Process, Energy and Environmental Technology, University College of Southeast Norway, Porsgrunn (Norway); Olsbye, Unni [Department of Chemistry, University of Oslo, Oslo (Norway); Jens, Klaus-Joachim, E-mail: Klaus.J.Jens@usn.no [Department of Process, Energy and Environmental Technology, University College of Southeast Norway, Porsgrunn (Norway)

    2017-07-14

    Methanol syntheses at low temperature in a liquid medium present an opportunity for full syngas conversion per pass. The aim of this work was to study the role of solvents polarity on low-temperature methanol synthesis reaction using eight different aprotic polar solvents. A “once through” catalytic system, which is composed of Cu nanoparticles and sodium methoxide, was used for methanol synthesis at 100°C and 20 bar syngas pressure. Solvent polarity rather than the 7–10 nm Cu (and 30 nm Cu on SiO{sub 2}) catalyst used dictated trend of syngas conversion. Diglyme with a dielectric constant (ε) = 7.2 gave the highest syngas conversion among the eight different solvents used. Methanol formation decreased with either increasing or decreasing solvent ε value of diglyme (ε = 7.2). To probe the observed trend, possible side reactions of methyl formate (MF), the main intermediate in the process, were studied. MF was observed to undergo two main reactions; (i) decarbonylation to form CO and MeOH and (ii) a nucleophilic substitution to form dimethyl ether and sodium formate. Decreasing polarity favored the decarbonylation side reaction while increasing polarity favored the nucleophilic substitution reaction. In conclusion, our results show that moderate polarity solvents, e.g., diglyme, favor MF hydrogenolysis and, hence, methanol formation, by retarding the other two possible side reactions.

  19. Effects of solvent polarity on mutual polypropylene grafting by electron beam irradiation

    International Nuclear Information System (INIS)

    Geraldo, A.B.C.; Moura, E.; Somessari, E.S.R.; Silveira, C.G.; Paes, H.A.; Souza, C.A.; Fernandes, W.; Manzoli, J.E.

    2011-01-01

    Complete text of publication follows. Copolymerization by grafting is a process largely known and the advantages of modifying polymers by radiation includes superimposition of properties related to the backbone and the grafted chains in the absence of an initiator. This process produces low byproduct levels, costs and hazards. Since polypropylene is applied in many industrial and commercial sectors, the grafting process is an alternative to improve some of its physical and chemical properties. The aim of this work was to verify the effect of distinct organic solvents on polypropylene grafting process by mutual irradiation applying absorbed doses from 30 kGy to 100 kGy at dose rates of 2.2 kGy/s and 22.4 kGy/s. All process were performed in atmosphere air presence. Styrene was the monomer grafted on polymer substrate and some non-polar and polar organic solvents, like toluene, xylene, acetone, methanol and its homologous, were used at distinct concentrations. The grafted samples were evaluated by degree of styrene grafting (gravimetric determination) and the Mid-FTIR spectrophotometry. As a general behavior, the degree of grafting increases when absorbed dose values increase in a specific solvent until a maximum dose value (50-70 kGy), after this, the degree of grafting decreases. Moreover, the grafting process have high yields when protic polar solvents are used. These results suggest the grafting process does not have dependence of substrate swelling, that is expected when a non-polar substrate and a non-polar media are in contact. The grafting, in this case, can be related to the free radical generation at protic polar solvents in a first step of process mechanism; these reactive specimens start the reaction on substrate surface to allow the accessibility of monomer species to active sites. Some reaction mechanisms are proposed.

  20. Ionic magnetic fluids in polar solvents with tuned counter-ions

    Energy Technology Data Exchange (ETDEWEB)

    Lopes Filomeno, C. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Grupo de Fluidos Complexos Inst. de Quimica, Univ. de Brasília, Brasília (DF) (Brazil); Kouyaté, M. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Cousin, F. [Lab. Léon Brillouin – CE-Saclay, Gif-sur-Yvette (France); Demouchy, G. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Dpt de physique, Univ. de Cergy Pontoise, Cergy-Pontoise (France); Dubois, E.; Michot, L.; Mériguet, G. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Perzynski, R., E-mail: regine.perzynski@upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Peyre, V.; Sirieix-Plénet, J. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Tourinho, F.A. [Grupo de Fluidos Complexos Inst. de Quimica, Univ. de Brasília, Brasília (DF) (Brazil)

    2017-06-01

    The aim of the present study is to propose a new reproducible method for preparing colloidal dispersions of electrostatically charged nanoparticles (NPs) in polar solvents with different kinds of counter-ions. Maghemite NPs are here dispersed in solvents of different dielectric constant, namely water, dimethylsulfoxide (DMSO) and an ionic liquid, ethylammonium nitrate (EAN). If the existence of a NP superficial charge happens to be necessary for the colloidal stability of the dispersions in these three solvents, the standard DLVO theory cannot be used any more to describe the colloidal stability in EAN. The structure of the dispersions and the strength of the interparticle repulsion are investigated by small angle X-ray scattering measurements, in association with Ludwig–Soret coefficient determinations. Specificities, associated to the nature of the counter-ions are identified in this work on the colloidal stability, on the interparticle repulsion and on the Ludwig–Soret coefficient. - Highlights: • A controlled synthesis of ionic magnetic fluids in three polar solvents is proposed. • Colloidal repulsion in the magnetic fluids depends on the counter-ion nature. • Soret coefficient of citrate-coated maghemite nanoparticles is probed in water-pH7. • Thermophilicity of nanoparticles depends on the nature of their counter-ions. • Nanoparticles dressed with same counter-ions have solvent-dependent thermoproperties.

  1. Influence of polar solvents on the enhancement of light-ends in ...

    African Journals Online (AJOL)

    Crude oil 'micelle' can be dispersed into fuels, oil and resin/asphalthene components using some hydrocarbon solvents. This can be adapted towards influencing/enhancing its product slates during the processing of crude oils. This research was carried out to investigate the effect of polar solvents (ethanol and acetone) in ...

  2. Solvent polarity scale on the fluorescence spectra of a dansyl monomer copolymerizable in aqueous media

    Science.gov (United States)

    Ren, Biye; Gao, Feng; Tong, Zhen; Yan, Yu

    1999-06-01

    A copolymerizable fluorescent monomer N-[2-[[[5-(N,N-dimethylamino)-1-naphthalenyl]sulfonyl]-amino]ethyl]-2-propenamide (DANSAEP) was synthesized, which exhibits dual fluorescence due to the twisted intramolecular charge transfer in the excited state. The emission maximum λem shifts from 463.3 nm in n-hexane to 530.0 nm in water, showing solvent polarity dependence. The relations between λem and the conventional solvent polarity parameters ET(30) or Z are linear, dividing solvents into protic and aprotic groups. Kamlet's linear solvation energy relationship gives a good description for λem as a solvent polarity scale. The increment of dipole moment Δ μ at the excited state was estimated as 5.09 D with the solvatochromic analysis.

  3. How many molecular layers of polar solvent molecules control chemistry? The concept of compensating dipoles.

    Science.gov (United States)

    Langhals, Heinz; Braun, Patricia; Dietl, Christian; Mayer, Peter

    2013-09-27

    The extension of the solvent influence of the shell into the volume of a polar medium was examined by means of anti-collinear dipoles on the basis of the E(T)(30) solvent polarity scale (i.e., the molar energy of excitation of a pyridinium-N-phenolatebetaine dye; generally: E(T) =28,591 nm kcal mol(-1)/λmax) where no compensation effects were found. As a consequence, solvent polarity effects are concentrated to a very thin layer of a few thousand picometres around the solute where extensions into the bulk solvent become unimportant. A parallelism to the thin surface layer of water to the gas phase is discussed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Characterization of molecularly imprinted polymers using a new polar solvent titration method.

    Science.gov (United States)

    Song, Di; Zhang, Yagang; Geer, Michael F; Shimizu, Ken D

    2014-07-01

    A new method of characterizing molecularly imprinted polymers (MIPs) was developed and tested, which provides a more accurate means of identifying and measuring the molecular imprinting effect. In the new polar solvent titration method, a series of imprinted and non-imprinted polymers were prepared in solutions containing increasing concentrations of a polar solvent. The polar solvent additives systematically disrupted the templation and monomer aggregation processes in the prepolymerization solutions, and the extent of disruption was captured by the polymerization process. The changes in binding capacity within each series of polymers were measured, providing a quantitative assessment of the templation and monomer aggregation processes in the imprinted and non-imprinted polymers. The new method was tested using three different diphenyl phosphate imprinted polymers made using three different urea functional monomers. Each monomer had varying efficiencies of templation and monomer aggregation. The new MIP characterization method was found to have several advantages. To independently verify the new characterization method, the MIPs were also characterized using traditional binding isotherm analyses. The two methods appeared to give consistent conclusions. First, the polar solvent titration method is less susceptible to false positives in identifying the imprinting effect. Second, the method is able to differentiate and quantify changes in binding capacity, as measured at a fixed guest and polymer concentration, arising from templation or monomer aggregation processes in the prepolymerization solution. Third, the method was also easy to carry out, taking advantage of the ease of preparing MIPs. Copyright © 2014 John Wiley & Sons, Ltd.

  5. Evidence for the TICT mediated nonradiative deexcitation process for the excited coumarin-1 dye in high polarity protic solvents

    Energy Technology Data Exchange (ETDEWEB)

    Barik, Atanu [Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Kumbhakar, Manoj [Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Nath, Sukhendu [Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Pal, Haridas [Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India)

    2005-08-29

    Photophysical properties of coumarin-1 (C1) dye in different protic solvents have been investigated using steady-state and time-resolved fluorescence measurements. Correlation of the Stokes' shifts ({delta}{nu}-bar ) with the solvent polarity ({delta}f) suggests the intramolecular charge transfer (ICT) character for the dye fluorescent state. Fluorescence quantum yields ({phi}{sub f}) and lifetimes ({tau}{sub f}) of the dye show an abrupt reduction in high polarity solvents having {delta}f >{approx}0.28. In these solvents {tau}{sub f} is seen to be strongly temperature dependent, though it is temperature independent in solvents with {delta}f <{approx}0.28. It is inferred that in high polarity protic solvents there is a participation of an additional nonradiative decay process via the involvement of twisted intramolecular charge transfer (TICT) state. Unlike present results, no involvement of TICT state was observed even in strongly polar aprotic solvent like acetonitrile. It is indicated that the intermolecular hydrogen bonding of the dye with protic solvents in addition with the solvent polarity helps in the stabilization of the TICT state for C1 dye. Unlike most TICT molecules, the activation barrier ({delta}E{sub a}) for the TICT mediated nonradiative process for C1 dye is seen to increase with solvent polarity. This is rationalized on the basis of the assumption that the TICT to ground state conversion is the activation-controlled rate-determining step for the present system than the usual ICT to TICT conversion as encountered for most other TICT molecules.

  6. Covalent Surface Modification of Silicon Oxides with Alcohols in Polar Aprotic Solvents.

    Science.gov (United States)

    Lee, Austin W H; Gates, Byron D

    2017-09-05

    Alcohol-based monolayers were successfully formed on the surfaces of silicon oxides through reactions performed in polar aprotic solvents. Monolayers prepared from alcohol-based reagents have been previously introduced as an alternative approach to covalently modify the surfaces of silicon oxides. These reagents are readily available, widely distributed, and are minimally susceptible to side reactions with ambient moisture. A limitation of using alcohol-based compounds is that previous reactions required relatively high temperatures in neat solutions, which can degrade some alcohol compounds or could lead to other unwanted side reactions during the formation of the monolayers. To overcome these challenges, we investigate the condensation reaction of alcohols on silicon oxides carried out in polar aprotic solvents. In particular, propylene carbonate has been identified as a polar aprotic solvent that is relatively nontoxic, readily accessible, and can facilitate the formation of alcohol-based monolayers. We have successfully demonstrated this approach for tuning the surface chemistry of silicon oxide surfaces with a variety of alcohol containing compounds. The strategy introduced in this research can be utilized to create silicon oxide surfaces with hydrophobic, oleophobic, or charged functionalities.

  7. In silico study of amphiphilic nanotubes based on cyclic peptides in polar and non-polar solvent

    DEFF Research Database (Denmark)

    Vijayakumar, Vinodhkumar; Vijayaraj, Ramadoss; Peters, Günther H.J.

    2016-01-01

    The stability of cyclic peptide assemblies (CPs) forming a macromolecular nanotube structure was investigated in solvents of different polarity using computational methods. The stability and structure of the complexes were studied using traditional molecular dynamics (MD). Energy of dissociation ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-30

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

  9. Solvent wash solution

    International Nuclear Information System (INIS)

    Neace, J.C.

    1986-01-01

    This patent describes a process for removing diluent degradation products from a solvent extraction solution comprising an admixture of an organic extractant for uranium and plutonium and a non-polar organic liquid diluent, which has been used to recover uranium and plutonium from spent nuclear fuel. Comprising combining a wash solution consisting of: (a) water; and (b) a positive amount up to about, an including, 50 volume percent of at least one highly-polar water-miscible organic solvent, based on the total volume of the water and the highly-polar organic solvent, with the solvent extraction solution after uranium and plutonium values have been stripped from the solvent extraction solution, the diluent degradation products dissolving in the highly-polar organic solvent and the extractant and diluent of the extraction solution not dissolving in the highly-polar organic solvent, and separating the highly-polar organic solvent and the extraction solution to obtain a purified extraction solution

  10. Lid opening and conformational stability of T1 Lipase is mediated by increasing chain length polar solvents

    Directory of Open Access Journals (Sweden)

    Jonathan Maiangwa

    2017-05-01

    Full Text Available The dynamics and conformational landscape of proteins in organic solvents are events of potential interest in nonaqueous process catalysis. Conformational changes, folding transitions, and stability often correspond to structural rearrangements that alter contacts between solvent molecules and amino acid residues. However, in nonaqueous enzymology, organic solvents limit stability and further application of proteins. In the present study, molecular dynamics (MD of a thermostable Geobacillus zalihae T1 lipase was performed in different chain length polar organic solvents (methanol, ethanol, propanol, butanol, and pentanol and water mixture systems to a concentration of 50%. On the basis of the MD results, the structural deviations of the backbone atoms elucidated the dynamic effects of water/organic solvent mixtures on the equilibrium state of the protein simulations in decreasing solvent polarity. The results show that the solvent mixture gives rise to deviations in enzyme structure from the native one simulated in water. The drop in the flexibility in H2O, MtOH, EtOH and PrOH simulation mixtures shows that greater motions of residues were influenced in BtOH and PtOH simulation mixtures. Comparing the root mean square fluctuations value with the accessible solvent area (SASA for every residue showed an almost correspondingly high SASA value of residues to high flexibility and low SASA value to low flexibility. The study further revealed that the organic solvents influenced the formation of more hydrogen bonds in MtOH, EtOH and PrOH and thus, it is assumed that increased intraprotein hydrogen bonding is ultimately correlated to the stability of the protein. However, the solvent accessibility analysis showed that in all solvent systems, hydrophobic residues were exposed and polar residues tended to be buried away from the solvent. Distance variation of the tetrahedral intermediate packing of the active pocket was not conserved in organic solvent

  11. Effect of electrostatic interaction on thermochemical behavior of 12-crown-4 ether in various polar solvents

    International Nuclear Information System (INIS)

    Barannikov, Vladimir P.; Guseynov, Sabir S.; Vyugin, Anatoliy I.

    2010-01-01

    The enthalpies of solution of 12-crown-4 ether have been measured in chloroform, ethyl acetate, acetone, pyridine, acetonitrile and methanol at 298.15 K. The values of enthalpy of solvation and solute-solvent interaction were determined from the obtained results and similar literature data for 12-crown-4 in solvents of various polarities. It was shown that the certain correlation is observed between the enthalpy of solute-solvent interaction and the squared dipole moment of the solvent molecules for solutions in tetrachlormethane, ethyl acetate, pyridine, acetonitrile, DMF, DMSO and propylene carbonate. This means that the electrostatic interaction of 12-crown-4 with polar solvent molecules contributes significantly to the exothermic effect of solvation. The understated negative value was found for the enthalpy of interaction of 12-crown-4 with acetone that can be connected with domination of low polar conformer of the crown ether in acetone medium. The most negative values of enthalpy of solvation are observed for solutions in chloroform and water because of hydrogen bonding between O-atoms of crown ether and molecules of the indicated solvents. This effect is not observed for methanol. The negative coefficient of pairwise solute-solute interaction in methanol indicates that the effects of solvophobic solute-solute interaction and H-bonding of the ether molecule with chain associates of methanol are not evinced in the thermochemical behavior of 12-crown-4.

  12. Alkali-assisted coal extraction with polar aprotic solvents

    Energy Technology Data Exchange (ETDEWEB)

    Makgato, M.H.; Moitsheki, L.J.; Shoko, L.; Kgobane, B.L.; Morgan, D.L.; Focke, W.W. [SARChI Chair in Carbon Technology and Materials, Institute of Applied Materials, University of Pretoria, Pretoria 0002 (South Africa)

    2009-04-15

    Coal extraction experiments were conducted using a coal, containing ca. 10% ash, from the Tshikondeni mine in South Africa. This coal dissolves only to a limited extent in pure polar aprotic solvents such as dimethylformamide (DMF) and N-methyl-2-pyrrolidinone (NMP). However, the addition of a strong base, e.g. sodium hydroxide (NaOH) or sodium tert-butoxide increased the degree of coal dissolution in these organic solvents. Depending on the extraction conditions, carbon extraction efficiencies of up to 90% were obtained. Carbon precursor material was recovered from the solution as a gel by precipitation with water. Ash content was reduced from 10% in the coal to less than 1.6% in the coal extracts. Sodium sulfide (Na{sub 2}S) addition further reduced ash content and aided the recovery of carbon precursors that led to graphitizable cokes but the degree of extraction was significantly reduced. (author)

  13. Biofiltration of paint solvent mixtures in two reactor types: overloading by polar components.

    Science.gov (United States)

    Paca, Jan; Halecky, Martin; Misiaczek, Ondrej; Kozliak, Evguenii I; Jones, Kim

    2012-01-01

    Steady-state performances of a trickle bed reactor (TBR) and a biofilter (BF) in loading experiments with increasing inlet concentrations of polar solvents, acetone, methyl ethyl ketone, methyl isobutyl ketone and n-butyl acetate, were investigated, along with the system's dynamic responses. Throughout the entire experimentation time, a constant loading rate of aromatic components of 4 g(c)·m(-3)·h(-1) was maintained to observe the interactions between the polar substrates and aromatic hydrocarbons. Under low combined substrate loadings, the BF outperformed TBR not only in the removal of aromatic hydrocarbons but also in the removal of polar substrates. However, increasing the loading rate of polar components above the threshold value of 31-36 g(c)·m(-3)·h(-1) resulted in a steep and significant drop in the removal efficiencies of both polar (except for butyl acetate) and hydrophobic components, which was more pronounced in the BF; so the relative TBR/BF efficiency became reversed under such overloading conditions. A step-drop of the overall OL(POLAR) (combined loading by polar air pollutants) from overloading values to 7 g(c)·m(-3)·h(-1) resulted in an increase of all pollutant removal efficiencies, although in TBR the recovery was preceded by lag periods lasting between 5 min (methyl ethyl ketone) to 3.7 h (acetone). The occurrence of lag periods in the TBR recovery was, in part, due to the saturation of mineral medium with water-soluble polar solvents, particularly, acetone. The observed bioreactor behavior was consistent with the biological steps being rate-limiting.

  14. Lipase mediated synthesis of rutin fatty ester: Study of its process parameters and solvent polarity.

    Science.gov (United States)

    Vaisali, C; Belur, Prasanna D; Regupathi, Iyyaswami

    2017-10-01

    Lipophilization of antioxidants is recognized as an effective strategy to enhance solubility and thus effectiveness in lipid based food. In this study, an effort was made to optimize rutin fatty ester synthesis in two different solvent systems to understand the influence of reaction system hydrophobicity on the optimum conditions using immobilised Candida antartica lipase. Under unoptimized conditions, 52.14% and 13.02% conversion was achieved in acetone and tert-butanol solvent systems, respectively. Among all the process parameters, water activity of the system was found to show highest influence on the conversion in each reaction system. In the presence of molecular sieves, the ester production increased to 62.9% in tert-butanol system, unlike acetone system. Under optimal conditions, conversion increased to 60.74% and 65.73% in acetone and tert-butanol system, respectively. This study shows, maintaining optimal water activity is crucial in reaction systems having polar solvents compared to more non-polar solvents. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Synthesis of sol–gel silica particles in reverse micelles with mixed-solvent polar cores: tailoring nanoreactor structure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Bürglová, Kristýna; Hlaváč, Jan [Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry (Czech Republic); Bartlett, John R., E-mail: jbartlett@usc.edu.au [University of the Sunshine Coast, Faculty of Science, Health, Education and Engineering (Australia)

    2015-07-15

    In this paper, we describe a new approach for producing metal oxide nano- and microparticles via sol–gel processing in confined media (sodium bis(2-ethylhexyl)sulfosuccinate reverse micelles), in which the chemical and physical properties of the polar aqueous core of the reverse micelles are modulated by the inclusion of a second polar co-solvent. The co-solvents were selected for their capacity to solubilise compounds with low water solubility and included dimethylsulfoxide, dimethylformamide, ethylene glycol, n-propanol, dimethylacetamide and N-methylpyrrolidone. A broad range of processing conditions across the sodium bis(2-ethylhexyl)sulfosuccinate/cyclohexane/water phase diagram were identified that are suitable for preparing particles with dimensions <50 to >500 nm. In contrast, only a relatively narrow range of processing conditions were suitable for preparing such particles in the absence of the co-solvents, highlighting the role of the co-solvent in modulating the properties of the polar core of the reverse micelles. A mechanism is proposed that links the interactions between the various reactive sites on the polar head group of the surfactant and the co-solvent to the nucleation and growth of the particles.

  16. Solvent polarity controls the helical conformation of short peptides rich in Calpha-tetrasubstituted amino acids.

    Science.gov (United States)

    Bellanda, Massimo; Mammi, Stefano; Geremia, Silvano; Demitri, Nicola; Randaccio, Lucio; Broxterman, Quirinus B; Kaptein, Bernard; Pengo, Paolo; Pasquato, Lucia; Scrimin, Paolo

    2007-01-01

    The two peptides, rich in C(alpha)-tetrasubstituted amino acids, Ac-[Aib-L-(alphaMe)Val-Aib](2)-L-His-NH(2) (1) and Ac-[Aib-L-(alphaMe)Val-Aib](2)-O-tBu (2 a) are prevalently helical. They present the unique property of changing their conformation from the alpha- to the 3(10)-helix as a function of the polarity of the solvent: alpha in more polar solvents, 3(10) in less polar ones. Conclusive evidence of this reversible change of conformation is reported on the basis of the circular dichroism (CD) spectra and a detailed two-dimensional NMR analysis in two solvents (trifluoroethanol and methanol) refined with molecular dynamics calculations. The X-ray diffractometric analysis of the crystals of both peptides reveals that they assume a prevalent 3(10)-helix conformation in the solid state. This conformation is practically superimposable on that obtained from the NMR analysis of 1 in methanol. The NMR results further validate the reported CD signature of the 3(10)-helix and the use of the CD technique for its assessment.

  17. Gels with exceptional thermal stability formed by bis(amino acid) oxalamide gelators and solvents of low polarity.

    Science.gov (United States)

    Makarević, Janja; Jokić, Milan; Frkanec, Leo; Katalenić, Darinka; Zinić, Mladen

    2002-10-07

    Some bis (amino acid) oxalamide gelators form common thermo-reversible gels with various organic solvents but also gels of exceptional thermal stability with some solvents of medium and low polarity; the latter gels can be heated up to 50 degrees C higher temperatures than the bp of the solvent without apparent gel-to-sol transition.

  18. Direct Detection of the Ion Pair to Free Ions Transformation upon Complexation with an Ion Receptor in Non‐Polar Solvents by using Conductometry

    Science.gov (United States)

    Iseda, Kazuya

    2018-01-01

    Abstract In this study, we performed conductometry in various organic solvents to directly detect the transformation from tetrabutylammonium chloride (TBACl) ion‐pair salt to the free ions through complexation with meso‐octamethylcalix[4]pyrrole (CP), which is a well‐known receptor for chloride anions. In the presence of CP, the conductivity of TBACl increases in various non‐polar solvents, indicating that complexation with CP enhances the ionic dissociation of TBACl in such non‐polar solvents. In other words, CP recognizes chloride as an ion‐paired salt as well as a free anion in non‐polar solvents. Additionally, the TBA(CP–Cl) complex exhibited a considerably lower ion‐pairing constant (K ip) than TBACl in non‐polar solvents, resulting in enhanced conductivity. Based on these findings, we can conclude that complexation of an anion with a hydrophobic anion receptor will be useful for creating functional and stimuli‐responsive soft materials in organic solvents using coulombic forces. PMID:29610717

  19. Direct Detection of the Ion Pair to Free Ions Transformation upon Complexation with an Ion Receptor in Non-Polar Solvents by using Conductometry.

    Science.gov (United States)

    Iseda, Kazuya; Kokado, Kenta; Sada, Kazuki

    2018-03-01

    In this study, we performed conductometry in various organic solvents to directly detect the transformation from tetrabutylammonium chloride ( TBACl ) ion-pair salt to the free ions through complexation with meso -octamethylcalix[4]pyrrole ( CP ), which is a well-known receptor for chloride anions. In the presence of CP , the conductivity of TBACl increases in various non-polar solvents, indicating that complexation with CP enhances the ionic dissociation of TBACl in such non-polar solvents. In other words, CP recognizes chloride as an ion-paired salt as well as a free anion in non-polar solvents. Additionally, the TBA(CP - Cl ) complex exhibited a considerably lower ion-pairing constant ( K ip ) than TBACl in non-polar solvents, resulting in enhanced conductivity. Based on these findings, we can conclude that complexation of an anion with a hydrophobic anion receptor will be useful for creating functional and stimuli-responsive soft materials in organic solvents using coulombic forces.

  20. Ultra-high performance size-exclusion chromatography in polar solvents.

    Science.gov (United States)

    Vancoillie, Gertjan; Vergaelen, Maarten; Hoogenboom, Richard

    2016-12-23

    Size-exclusion chromatography (SEC) is amongst the most widely used polymer characterization methods in both academic and industrial polymer research allowing the determination of molecular weight and distribution parameters, i.e. the dispersity (Ɖ), of unknown polymers. The many advantages, including accuracy, reproducibility and low sample consumption, have contributed to the worldwide success of this analytical technique. The current generation of SEC systems have a stationary phase mostly containing highly porous, styrene-divinylbenzene particles allowing for a size-based separation of various polymers in solution but limiting the flow rate and solvent compatibility. Recently, sub-2μm ethylene-bridged hybrid (BEH) packing materials have become available for SEC analysis. These packing materials can not only withstand much higher pressures up to 15000psi but also show high spatial stability towards different solvents. Combining these BEH columns with the ultra-high performance LC (UHPLC) technology opens up UHP-SEC analysis, showing strongly reduced runtimes and unprecedented solvent compatibility. In this work, this novel characterization technique was compared to conventional SEC using both highly viscous and highly polar solvents as eluent, namely N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF) and methanol, focusing on the suitability of the BEH-columns for analysis of highly functional polymers. The results show a high functional group compatibility comparable with conventional SEC with remarkably short runtimes and enhanced resolution in methanol. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Solvent effect on the degree of (a)synchronicity in polar Diels-Alder reactions from the perspective of the reaction force constant analysis.

    Science.gov (United States)

    Yepes, Diana; Martínez-Araya, Jorge I; Jaque, Pablo

    2017-12-29

    In this work, we computationally evaluated the influence of six different molecular solvents, described as a polarizable continuum model at the M06-2X/6-31+G(d,p) level, on the activation barrier/reaction rate, overall energy change, TS geometry, and degree of (a)synchronicity of two concerted Diels-Alder cycloadditions of acrolein (R1) and its complex with Lewis acid acrolein···BH 3 (R2) to cyclopentadiene. In gas-phase, we found that both exothermicity and activation barrier are only reduced by about 2.0 kcal mol -1 , and the asynchronicity character of the mechanism is accentuated when BH 3 is included. An increment in the solvent's polarity lowers the activation energy of R1 by 1.3 kcal mol -1 , while for R2 the reaction rate is enhanced by more than 2000 times at room temperature (i.e., the activation energy decreases by 4.5 kcal mol -1 ) if the highest polar media is employed. Therefore, a synergistic effect is achieved when both external agents, i.e., Lewis acid catalyst and polar solvent, are included together. This effect was ascribed to the ability of the solvent to favor the encounter between cyclopentadiene and acrolein···BH 3 . This was validated by the asymmetry of the TS which becomes highly pronounced when either both or just BH 3 is considered or the solvent's polarity is increased. Finally, the reaction force constant κ(ξ) reveals that an increment in the solvent's polarity is able to turn a moderate asynchronous mechanism of the formation of the new C-C σ-bonds into a highly asynchronous one. Graphical abstract A synergistic effect is achieved when both external agents, i.e., Lewis acid catalyst and polar solvent, are included together: lowered energy barriers and increased asynchronicities.

  2. Influence of polar solvents on photovoltaic performance of Monascusred dye-sensitized solar cell

    Science.gov (United States)

    Lee, Jae Wook; Kim, Tae Young; Ko, Hyun Seok; Han, Shin; Lee, Suk-Ho; Park, Kyung Hee

    Dye-sensitized solar cells (DSSCs) were assembled using natural dyes extracted from Monascus red pigment as a sensitizer. In this work, we studied the adsorption characteristics for harvesting sunlight and the electrochemical behavior for electron transfer in Monascus red DSSC using different solvents. The effect of polar aprotic and protic solvents including water, ethanol, and dimethylsulfoxide (DMSO) used in the sensitization process was investigated for the improvement in conversion efficiency of a cell. As for the Monascus red dye-sensitized electrode in DMSO solvent, the solar cell yields a short-circuit current density (Jsc) of 1.23 mA/cm2, a photovoltage (Voc) of 0.75 V, and a fill factor of 0.72, corresponding to an energy conversion efficiency (η) of 0.66%.

  3. Salting out the polar polymorph: analysis by alchemical solvent transformation.

    Science.gov (United States)

    Duff, Nathan; Dahal, Yuba Raj; Schmit, Jeremy D; Peters, Baron

    2014-01-07

    We computationally examine how adding NaCl to an aqueous solution with α- and γ-glycine nuclei alters the structure and interfacial energy of the nuclei. The polar γ-glycine nucleus in pure aqueous solution develops a melted layer of amorphous glycine around the nucleus. When NaCl is added, a double layer is formed that stabilizes the polar glycine polymorph and eliminates the surface melted layer. In contrast, the non-polar α-glycine nucleus is largely unaffected by the addition of NaCl. To quantify the stabilizing effect of NaCl on γ-glycine nuclei, we alchemically transform the aqueous glycine solution into a brine solution of glycine. The alchemical transformation is performed both with and without a nucleus in solution and for nuclei of α-glycine and γ-glycine polymorphs. The calculations show that adding 80 mg/ml NaCl reduces the interfacial free energy of a γ-glycine nucleus by 7.7 mJ/m(2) and increases the interfacial free energy of an α-glycine nucleus by 3.1 mJ/m(2). Both results are consistent with experimental reports on nucleation rates which suggest: J(α, brine) transformation approach can predict the results for both polar and non-polar polymorphs. The results suggest a general "salting out" strategy for obtaining polar polymorphs and also a general approach to computationally estimate the effects of solvent additives on interfacial free energies for nucleation.

  4. Solvent polarity effects on hyperfine couplings of cyclohexadienyl-type radicals

    International Nuclear Information System (INIS)

    Vujosevic', D.; Scheuermann, R.; Dilger, H.; Tucker, I.M.; Martyniak, A.; McKenzie, I.; Roduner, E.

    2006-01-01

    In this study muon-spin rotation (μSR) serves as a tool for sensitive monitoring of the environment of muoniated radicals in isotropic liquids. A systematic investigation of the behaviour of the hyperfine coupling constants of cyclohexadienyl-type radicals is performed, and it is found that they are in linear dependence on solvent polarity, with certain deviations. These deviations are discussed in detail. It is found that with increasing length of the hydroxyalkyl substituent group the perturbation of the phenyl ring becomes smaller

  5. Solvent polarity effects on hyperfine couplings of cyclohexadienyl-type radicals

    Energy Technology Data Exchange (ETDEWEB)

    Vujosevic' , D. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Scheuermann, R. [Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Dilger, H. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Tucker, I.M. [Unilever Research and Development, Port Sunlight, Wirral CH63 3JW (United Kingdom); Martyniak, A. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); McKenzie, I. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Roduner, E. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany)]. E-mail: e.rodunder@ipc.uni-stuttgart.de

    2006-03-31

    In this study muon-spin rotation ({mu}SR) serves as a tool for sensitive monitoring of the environment of muoniated radicals in isotropic liquids. A systematic investigation of the behaviour of the hyperfine coupling constants of cyclohexadienyl-type radicals is performed, and it is found that they are in linear dependence on solvent polarity, with certain deviations. These deviations are discussed in detail. It is found that with increasing length of the hydroxyalkyl substituent group the perturbation of the phenyl ring becomes smaller.

  6. studies dielectric behaviour of some long chain alcohols and their mixtures with a non-polar solvent at various concentration

    International Nuclear Information System (INIS)

    Yaqub, M.; Ahmed, S.S.; Hussain, A.

    2006-01-01

    Dielectric constant, refractive index and the Kirkwood linear correlation factor of 1-propanol, 1-butanol and 1-pentanol in mixtures with carbon tetrachloride at various concentration have been measured at fixed frequency (100 KHz) at 303.15 K. For the study of dielectric properties of polar molecules in a non-polar solvent at different concentrations, polarization per unit volume and excess free-energy of mixing were evaluated at this temperature. In order to study the association of polar molecules in such a non-polar solvent, the Kirkwood correlation factor (g) between molecular pairs, which exists due to the hydrogen bond association suggesting the presence of some dimension in the liquid phase with a number of dimmers, was determined. The refractive index and dielectric constant measurements are expected to shed some light on the configuration of molecules in various mixtures, and give some idea about the specific interactions between components, which decrese with the increase in the concentration of alcohol. All the three mixtures showed different behaviour for the value of correlation factor (g) as a function of concentration. The response of 1-pentanol was broadly identical to that of small chain alcohols. The different behaviour of the correlation factor (g) was interpreted in terms of the Kirkwood-Frohlich theory, as it takes into account, explicitly, such type of short and long range interactions of a mixture of polar molecules with non-polar solvents. (author)

  7. Influence of polar solvents on photovoltaic performance of Monascusred dye-sensitized solar cell.

    Science.gov (United States)

    Lee, Jae Wook; Kim, Tae Young; Ko, Hyun Seok; Han, Shin; Lee, Suk-Ho; Park, Kyung Hee

    2014-05-21

    Dye-sensitized solar cells (DSSCs) were assembled using natural dyes extracted from Monascus red pigment as a sensitizer. In this work, we studied the adsorption characteristics for harvesting sunlight and the electrochemical behavior for electron transfer in Monascus red DSSC using different solvents. The effect of polar aprotic and protic solvents including water, ethanol, and dimethylsulfoxide (DMSO) used in the sensitization process was investigated for the improvement in conversion efficiency of a cell. As for the Monascus red dye-sensitized electrode in DMSO solvent, the solar cell yields a short-circuit current density (Jsc) of 1.23mA/cm(2), a photovoltage (Voc) of 0.75V, and a fill factor of 0.72, corresponding to an energy conversion efficiency (η) of 0.66%. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Solvent polarity and nanoscale morphology in bulk heterojunction organic solar cells: A case study

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Ajith [Centre for Nano-Bio-Polymer Science and Technology, Department of Physics, St. Thomas College, Pala, Kerala 686574 (India); Research and Development Centre, Bharathiar University, Coimbatore, Tamilnadu 641046 (India); Elsa Tom, Anju; Ison, V. V., E-mail: isonvv@yahoo.in, E-mail: praveen@materials.iisc.ernet.in [Centre for Nano-Bio-Polymer Science and Technology, Department of Physics, St. Thomas College, Pala, Kerala 686574 (India); Rao, Arun D.; Varman, K. Arul; Ranjith, K.; Ramamurthy, Praveen C., E-mail: isonvv@yahoo.in, E-mail: praveen@materials.iisc.ernet.in [Department of Materials Engineering, Indian Institute of Science Bangalore, Karnataka 560012 (India); Vinayakan, R. [Department of Chemistry, SVR NSS College Vazhoor, Kerala 686505 (India)

    2014-03-14

    Organic bulk heterojunction solar cells were fabricated under identical experimental conditions, except by varying the solvent polarity used for spin coating the active layer components and their performance was evaluated systematically. Results showed that presence of nitrobenzene-chlorobenzene composition governs the morphology of active layer formed, which is due to the tuning of solvent polarity as well as the resulting solubility of the P3HT:PCBM blend. Trace amount of nitrobenzene favoured the formation of better organised P3HT domains, as evident from conductive AFM, tapping mode AFM and surface, and cross-sectional SEM analysis. The higher interfacial surface area thus generated produced cells with high efficiency. But, an increase in the nitrobenzene composition leads to a decrease in cell performance, which is due to the formation of an active layer with larger size polymer domain networks with poor charge separation possibility.

  9. Solvent polarity and nanoscale morphology in bulk heterojunction organic solar cells: A case study

    International Nuclear Information System (INIS)

    Thomas, Ajith; Elsa Tom, Anju; Ison, V. V.; Rao, Arun D.; Varman, K. Arul; Ranjith, K.; Ramamurthy, Praveen C.; Vinayakan, R.

    2014-01-01

    Organic bulk heterojunction solar cells were fabricated under identical experimental conditions, except by varying the solvent polarity used for spin coating the active layer components and their performance was evaluated systematically. Results showed that presence of nitrobenzene-chlorobenzene composition governs the morphology of active layer formed, which is due to the tuning of solvent polarity as well as the resulting solubility of the P3HT:PCBM blend. Trace amount of nitrobenzene favoured the formation of better organised P3HT domains, as evident from conductive AFM, tapping mode AFM and surface, and cross-sectional SEM analysis. The higher interfacial surface area thus generated produced cells with high efficiency. But, an increase in the nitrobenzene composition leads to a decrease in cell performance, which is due to the formation of an active layer with larger size polymer domain networks with poor charge separation possibility

  10. Polar-solvent-free colloidal synthesis of highly luminescent alkylammonium lead halide perovskite nanocrystals

    Science.gov (United States)

    Vybornyi, Oleh; Yakunin, Sergii; Kovalenko, Maksym V.

    2016-03-01

    A novel synthesis of hybrid organic-inorganic lead halide perovskite nanocrystals (CH3NH3PbX3, X = Br or I) that does not involve the use of dimethylformamide or other polar solvents is presented. The reaction between methylamine and PbX2 salts is conducted in a high-boiling nonpolar solvent (1-octadecene) in the presence of oleylamine and oleic acid as coordinating ligands. The resulting nanocrystals are characterized by high photoluminescence quantum efficiencies of 15-50%, outstanding phase purity and tunable shapes (nanocubes, nanowires, and nanoplatelets). Nanoplatelets spontaneously assemble into micrometer-length wires by face-to-face stacking. In addition, we demonstrate amplified spontaneous emission from thin films of green-emitting CH3NH3PbBr3 nanowires with low pumping thresholds of 3 μJ cm-2.A novel synthesis of hybrid organic-inorganic lead halide perovskite nanocrystals (CH3NH3PbX3, X = Br or I) that does not involve the use of dimethylformamide or other polar solvents is presented. The reaction between methylamine and PbX2 salts is conducted in a high-boiling nonpolar solvent (1-octadecene) in the presence of oleylamine and oleic acid as coordinating ligands. The resulting nanocrystals are characterized by high photoluminescence quantum efficiencies of 15-50%, outstanding phase purity and tunable shapes (nanocubes, nanowires, and nanoplatelets). Nanoplatelets spontaneously assemble into micrometer-length wires by face-to-face stacking. In addition, we demonstrate amplified spontaneous emission from thin films of green-emitting CH3NH3PbBr3 nanowires with low pumping thresholds of 3 μJ cm-2. Electronic supplementary information (ESI) available: Materials and methods, additional figures. See DOI: 10.1039/c5nr06890h

  11. Transfers of Colloidal Silica from Water into Organic Solvents of Intermediate Polarities

    Science.gov (United States)

    Kasseh; Keh

    1998-01-15

    Dispersions of discrete metal-oxide submicroparticles in organic solvents of medium polarities are uneasy to generate and weakly documented. We address this topic along two general methods focusing on silica. Successive transfers of colloidal particles from water into n-propanol and then into 1,2-dichloroethane by azeotropic distillation yield a stable organosol. The particles are found to be propanol-coated by surface esterification to the extent of 0.40 nm2 per molecule. Alternatively, centrifugation-redispersion cycles make it possible to obtain stable suspensions of unaltered silica in methanol and acetonitrile starting from an aqueous silicasol. Particles are characterized by various methods including nitrogen adsorption, transmission electron microscopy, dynamic light scattering, and electrophoresis. The stabilities of these suspensions in various organic solvents are investigated with special concern for the role of residual water. Stabilization of silica in methanol is inconspicuously related to solvent permittivity and prominently dependent on the presence of adsorbed water. In contrast, the acetonitrile silicasol, which is unaffected by residual water, displays electrophoretic behavior compatible with electrostatic stabilization. Copyright 1998 Academic Press. Copyright 1998Academic Press

  12. Decontamination of Oils Contaminated with Polychlorinated Biphenyls and Dibenzyl Disulfide Using Polar Aprotic Solvents

    Czech Academy of Sciences Publication Activity Database

    Kaštánek, František; Matějková, Martina; Spáčilová, Lucie; Maléterová, Ywetta; Kaštánek, P.; Šolcová, Olga

    2015-01-01

    Roč. 4, č. 2 (2015), s. 41-48 ISSN 2319-5967 R&D Projects: GA TA ČR(CZ) TA04020151 Institutional support: RVO:67985858 Keywords : corrosive sulfur * dibenzyl disulfide * polar aprotic solvents Subject RIV: CI - Industrial Chemistry, Chemical Engineering http://www.ijesit.com/Volume%204/Issue%202/IJESIT201502_06.pdf

  13. Comparison of methanol and isopropanol as wash solvents for determination of hair cortisol concentration in grizzly bears and polar bears.

    Science.gov (United States)

    Kroshko, Thomas; Kapronczai, Luciene; Cattet, Marc R L; Macbeth, Bryan J; Stenhouse, Gordon B; Obbard, Martyn E; Janz, David M

    2017-01-01

    Methodological differences among laboratories are recognized as significant sources of variation in quantification of hair cortisol concentration (HCC). An important step in processing hair, particularly when collected from wildlife, is the choice of solvent used to remove or "wash" external hair shaft cortisol prior to quantification of HCC. The present study systematically compared methanol and isopropanol as wash solvents for their efficiency at removing external cortisol without extracting internal hair shaft cortisol in samples collected from free-ranging grizzly bears and polar bears. Cortisol concentrations in solvents and hair were determined in each of one to eight washes of hair with each solvent independently. •There were no significant decreases in internal hair shaft cortisol among all eight washes for either solvent, although methanol removed detectable hair surface cortisol after one wash in grizzly bear hair whereas hair surface cortisol was detected in all eight isopropanol washes.•There were no significant differences in polar bear HCC washed one to eight times with either solvent, but grizzly bear HCC was significantly greater in hair washed with isopropanol compared to methanol.•There were significant differences in HCC quantified using different commercial ELISA kits commonly used for HCC determinations.

  14. Use of uranyl nitrate as a shift reagent in polar and inert solvents

    International Nuclear Information System (INIS)

    Nosov, B.P.

    1988-01-01

    This work examines the effect of uranyl nitrate as a shift reagent on the PMR spectra of different organic molecules in polar and inert solvents. In order to identify the coordination site of the uranyl ion, its effect on the spectra of amino acids and acetic or propionic acids in water was compared. It was found that the induced shifts of the protons in the corresponding positions of the different acids after addition of uranyl nitrate agreed to within ±0.01 ppm. When nitrogenous bases such as diethylamine and pyridine were added to solutions of the carboxylic acids with uranyl nitrate, an increase in the induced chemical shift of the resonance signals occurred. These facts suggest the coordination of the uranyl ion with the carboxyl oxygen both for acetic and propionic acids and for amino acids. The authors established that the addition of uranyl nitrate to solutions of organic compounds caused different downfield shifts of the resonance signals from the protons. In polar solvents shifts induced by uranyl nitrate in the PMR spectra of carboxylic acids occur only when nitrogenous bases are added

  15. Carbon nanotube enhanced membrane distillation for online preconcentration of trace pharmaceuticals in polar solvents.

    Science.gov (United States)

    Gethard, Ken; Mitra, Somenath

    2011-06-21

    Carbon nanotube enhanced membrane distillation (MD) is presented as a novel, online analytical preconcentration method for removing polar solvents thereby concentrating the analytes, making this technique an alternate to conventional thermal evaporation. In a carbon nanotube immobilized membrane (CNIM), the CNTs serve as sorbent sites and provide additional pathways for enhanced solvent vapor transport, thus enhancing preconcentration. Enrichment using CNIM doubled compared to membranes without CNTs, while the methanol flux and mass transfer coefficients increased by 61% and 519% respectively. The carbon nanotube enhanced MD process showed excellent precision (RSD of 3-5%), linearity, and the detection limits were in the range of 0.001 to 0.009 mg L(-1) by HPLC analysis.

  16. Microfluidic Extraction of Biomarkers using Water as Solvent

    Science.gov (United States)

    Amashukeli, Xenia; Manohara, Harish; Chattopadhyay, Goutam; Mehdi, Imran

    2009-01-01

    A proposed device, denoted a miniature microfluidic biomarker extractor (mu-EX), would extract trace amounts of chemicals of interest from samples, such as soils and rocks. Traditionally, such extractions are performed on a large scale with hazardous organic solvents; each solvent capable of dissolving only those molecules lying within narrow ranges of specific chemical and physical characteristics that notably include volatility, electric charge, and polarity. In contrast, in the mu-EX, extractions could be performed by use of small amounts (typically between 0.1 and 100 L) of water as a universal solvent. As a rule of thumb, in order to enable solvation and extraction of molecules, it is necessary to use solvents that have polarity sufficiently close to the polarity of the target molecules. The mu-EX would make selection of specific organic solvents unnecessary, because mu-EX would exploit a unique property of liquid water: the possibility of tuning its polarity to match the polarity of organic solvents appropriate for extraction of molecules of interest. The change of the permittivity of water would be achieved by exploiting interactions between the translational states of water molecules and an imposed electromagnetic field in the frequency range of 300 to 600 GHz. On a molecular level, these interactions would result in disruption of the three-dimensional hydrogen-bonding network among liquid-water molecules and subsequent solvation and hydrolysis of target molecules. The mu-EX is expected to be an efficient means of hydrolyzing chemical bonds in complex macromolecules as well and, thus, enabling analysis of the building blocks of these complex chemical systems. The mu-EX device would include a microfluidic channel, part of which would lie within a waveguide coupled to an electronically tuned source of broad-band electromagnetic radiation in the frequency range from 300 to 600 GHz (see figure). The part of the microfluidic channel lying in the waveguide would

  17. Qualitative and quantitative evaluation of solvent systems for countercurrent separation.

    Science.gov (United States)

    Friesen, J Brent; Ahmed, Sana; Pauli, Guido F

    2015-01-16

    Rational solvent system selection for countercurrent chromatography and centrifugal partition chromatography technology (collectively known as countercurrent separation) studies continues to be a scientific challenge as the fundamental questions of comparing polarity range and selectivity within a solvent system family and between putative orthogonal solvent systems remain unanswered. The current emphasis on metabolomic investigations and analysis of complex mixtures necessitates the use of successive orthogonal countercurrent separation (CS) steps as part of complex fractionation protocols. Addressing the broad range of metabolite polarities demands development of new CS solvent systems with appropriate composition, polarity (π), selectivity (σ), and suitability. In this study, a mixture of twenty commercially available natural products, called the GUESSmix, was utilized to evaluate both solvent system polarity and selectively characteristics. Comparisons of GUESSmix analyte partition coefficient (K) values give rise to a measure of solvent system polarity range called the GUESSmix polarity index (GUPI). Solvatochromic dye and electrical permittivity measurements were also evaluated in quantitatively assessing solvent system polarity. The relative selectivity of solvent systems were evaluated with the GUESSmix by calculating the pairwise resolution (αip), the number of analytes found in the sweet spot (Nsw), and the pairwise resolution of those sweet spot analytes (αsw). The combination of these parameters allowed for both intra- and inter-family comparison of solvent system selectivity. Finally, 2-dimensional reciprocal shifted symmetry plots (ReSS(2)) were created to visually compare both the polarities and selectivities of solvent system pairs. This study helps to pave the way to the development of new solvent systems that are amenable to successive orthogonal CS protocols employed in metabolomic studies. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Influence of solvent polarization and non-uniform ion size on electrostatic properties between charged surfaces in an electrolyte solution

    Science.gov (United States)

    Sin, Jun-Sik

    2017-12-01

    In this paper, we study electrostatic properties between two similar or oppositely charged surfaces immersed in an electrolyte solution by using the mean-field approach accounting for solvent polarization and non-uniform size effects. Applying a free energy formalism accounting for unequal ion sizes and orientational ordering of water dipoles, we derive coupled and self-consistent equations to calculate electrostatic properties between charged surfaces. Electrostatic properties for similarly charged surfaces depend on the counterion size but not on the coion size. Moreover, electrostatic potential and osmotic pressure between similarly charged surfaces are found to be increased with increasing counterion size. On the other hand, the corresponding ones between oppositely charged surfaces are related to both sizes of positive and negative ions. For oppositely charged surfaces, the electrostatic potential, number density of solvent molecules, and relative permittivity of an electrolyte having unequal ion sizes are not symmetric about the centerline between the charged surfaces. For either case, the consideration of solvent polarization results in a decrease in the electrostatic potential and the osmotic pressure compared to the case without the effect.

  19. Ionic Liquids in Selective Oxidation: Catalysts and Solvents.

    Science.gov (United States)

    Dai, Chengna; Zhang, Jie; Huang, Chongpin; Lei, Zhigang

    2017-05-24

    Selective oxidation has an important role in environmental and green chemistry (e.g., oxidative desulfurization of fuels and oxidative removal of mercury) as well as chemicals and intermediates chemistry to obtain high-value-added special products (e.g., organic sulfoxides and sulfones, aldehydes, ketones, carboxylic acids, epoxides, esters, and lactones). Due to their unique physical properties such as the nonvolatility, thermal stability, nonexplosion, high polarity, and temperature-dependent miscibility with water, ionic liquids (ILs) have attracted considerable attention as reaction solvents and media for selective oxidations and are considered as green alternatives to volatile organic solvents. Moreover, for easy separation and recyclable utilization, IL catalysts have attracted unprecedented attention as "biphasic catalyst" or "immobilized catalyst" by immobilizing metal- or nonmetal-containing ILs onto mineral or polymer supports to combine the unique properties of ILs (chemical and thermal stability, capacity for extraction of polar substrates and reaction products) with the extended surface of the supports. This review highlights the most recent outcomes on ILs in several important typical oxidation reactions. The contents are arranged in the series of oxidation of sulfides, oxidation of alcohols, epoxidation of alkenes, Baeyer-Villiger oxidation reaction, oxidation of alkanes, and oxidation of other compounds step by step involving ILs as solvents, catalysts, reagents, or their combinations.

  20. Estimate of electrostatic solvation free energy of electron in various polar solvents by using modified born equation

    International Nuclear Information System (INIS)

    Yamashita, Kazuo; Kitamura, Mitsutaka; Imai, Hideo

    1976-01-01

    The modified Born equation was tentatively applied to estimate the electrostatic free energies of solvation of the electron in various polar solvents. The related data of halide ions and a datum of the hydration free energy of the electron obtained by radiation chemical studies were used for the numerical calculations. (auth.)

  1. Investigation of the Use of a Bio-Derived Solvent for Non-Solvent-Induced Phase Separation (NIPS Fabrication of Polysulfone Membranes

    Directory of Open Access Journals (Sweden)

    Xiaobo Dong

    2018-05-01

    Full Text Available Organic solvents, such as N-methyl-2-pyrrolidone (NMP and dimethylacetamide (DMAc, have been traditionally used to fabricate polymeric membranes. These solvents may have a negative impact on the environment and human health; therefore, using renewable solvents derived from biomass is of great interest to make membrane fabrication sustainable. Methyl-5-(dimethylamino-2-methyl-5-oxopentanoate (Rhodiasolv PolarClean is a bio-derived, biodegradable, nonflammable and nonvolatile solvent. Polysulfone is a commonly used polymer to fabricate membranes due to its thermal stability, strong mechanical strength and good chemical resistance. From cloud point curves, PolarClean showed potential to be a solvent for polysulfone. Membranes prepared with PolarClean were investigated in terms of their morphology, porosity, water permeability and protein rejection, and were compared to membranes prepared with traditional solvents. The pores of polysulfone/PolarClean membranes were sponge-like, and the membranes displayed higher water flux values (176.0 ± 8.8 LMH along with slightly higher solute rejection (99.0 ± 0.51%. On the other hand, PSf/DMAc membrane pores were finger-like with lower water flux (63.1 ± 12.4 LMH and slightly lower solute rejection (96 ± 2.00% when compared to PSf/PolarClean membranes.

  2. 10.6% Certified Colloidal Quantum Dot Solar Cells via Solvent-Polarity-Engineered Halide Passivation.

    Science.gov (United States)

    Lan, Xinzheng; Voznyy, Oleksandr; García de Arquer, F Pelayo; Liu, Mengxia; Xu, Jixian; Proppe, Andrew H; Walters, Grant; Fan, Fengjia; Tan, Hairen; Liu, Min; Yang, Zhenyu; Hoogland, Sjoerd; Sargent, Edward H

    2016-07-13

    Colloidal quantum dot (CQD) solar cells are solution-processed photovoltaics with broad spectral absorption tunability. Major advances in their efficiency have been made via improved CQD surface passivation and device architectures with enhanced charge carrier collection. Herein, we demonstrate a new strategy to improve further the passivation of CQDs starting from the solution phase. A cosolvent system is employed to tune the solvent polarity in order to achieve the solvation of methylammonium iodide (MAI) and the dispersion of hydrophobic PbS CQDs simultaneously in a homogeneous phase, otherwise not achieved in a single solvent. This process enables MAI to access the CQDs to confer improved passivation. This, in turn, allows for efficient charge extraction from a thicker photoactive layer device, leading to a certified solar cell power conversion efficiency of 10.6%, a new certified record in CQD photovoltaics.

  3. The Future of Polar Organometallic Chemistry Written in Bio-Based Solvents and Water.

    Science.gov (United States)

    García-Álvarez, Joaquín; Hevia, Eva; Capriati, Vito

    2018-06-19

    There is a strong imperative to reduce the release of volatile organic compounds (VOCs) into the environment, and many efforts are currently being made to replace conventional hazardous VOCs in favour of safe, green and bio-renewable reaction media that are not based on crude petroleum. Recent ground-breaking studies from a few laboratories worldwide have shown that both Grignard and (functionalised) organolithium reagents, traditionally handled under strict exclusion of air and humidity and in anhydrous VOCs, can smoothly promote both nucleophilic additions to unsaturated substrates and nucleophilic substitutions in water and other bio-based solvents (glycerol, deep eutectic solvents), competitively with protonolysis, at room temperature and under air. The chemistry of polar organometallics in the above protic media is a complex phenomenon influenced by several factors, and understanding its foundational character is surely stimulating in the perspective of the development of a sustainable organometallic chemistry. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. An absorbing microwave micro-solid-phase extraction device used in non-polar solvent microwave-assisted extraction for the determination of organophosphorus pesticides

    International Nuclear Information System (INIS)

    Wang Ziming; Zhao Xin; Xu Xu; Wu Lijie; Su Rui; Zhao Yajing; Jiang Chengfei; Zhang Hanqi; Ma Qiang; Lu Chunmei; Dong Deming

    2013-01-01

    Highlights: ► An absorbing microwave μ-SPE device packed with activated carbon was used. ► Absorbing microwave μ-SPE device was made and used to enrich the analytes. ► Absorbing microwave μ-SPE device was made and used to heat samples directly. ► MAE-μ-SPE was applied to the extraction of OPPs with non-polar solvent only. - Abstract: A single-step extraction-cleanup method, including microwave-assisted extraction (MAE) and micro-solid-phase extraction (μ-SPE), was developed for the extraction of ten organophosphorus pesticides in vegetable and fruit samples. Without adding any polar solvent, only one kind of non-polar solvent (hexane) was used as extraction solvent in the whole extraction step. Absorbing microwave μ-SPE device, was prepared by packing activated carbon with microporous polypropylene membrane envelope, and used as not only the sorbent in μ-SPE, but also the microwave absorption medium. Some experimental parameters effecting on extraction efficiency was investigated and optimized. 1.0 g of sample, 8 mL of hexane and three absorbing microwave μ-SPE devices were added in the microwave extraction vessel, the extraction was carried out under 400 W irradiation power at 60 °C for 10 min. The extracts obtained by MAE-μ-SPE were directly analyzed by GC–MS without any clean-up process. The recoveries were in the range of 93.5–104.6%, and the relative standard deviations were lower than 8.7%.

  5. Salting-out-enhanced ionic liquid microextraction with a dual-role solvent for simultaneous determination of trace pollutants with a wide polarity range in aqueous samples.

    Science.gov (United States)

    Gao, Man; Qu, Jingang; Chen, Kai; Jin, Lide; Dahlgren, Randy Alan; Wang, Huili; Tan, Chengxia; Wang, Xuedong

    2017-11-01

    In real aquatic environments, many occupational pollutants with a wide range of polarities coexist at nanogram to milligram per liter levels. Most reported microextraction methods focus on extracting compounds with similar properties (e.g., polarity or specific functional groups). Herein, we developed a salting-out-enhanced ionic liquid microextraction based on a dual-role solvent (SILM-DS) for simultaneous detection of tetracycline, doxycycline, bisphenol A, triclosan, and methyltriclosan, with log K ow ranging from -1.32 to 5.40 in complex milk and environmental water matrices. The disperser in the ionic-liquid-based dispersive liquid-liquid microextraction was converted to the extraction solvent in the subsequent salting-out-assisted microextraction procedures, and thus a single solvent performed a dual role as both extractant and disperser in the SILM-DS process. Acetonitrile was selected as the dual-role solvent because of its strong affinity for both ionic liquids and water, as well as the extractant in the salting-out step. Optimized experimental conditions were 115 μL [C 8 MIM][PF 6 ] as extractor, 1200 μL acetonitrile as dual-role solvent, pH 2.0, 5.0 min ultrasound extraction time, 3.0 g Na 2 SO 4 , and 3.0 min vortex extraction time. Under optimized conditions, the recoveries of the five pollutants ranged from 74.5 to 106.9%, and their LODs were 0.12-0.75 μg kg -1 in milk samples and 0.11-0.79 μg L -1 in environmental waters. Experimental precision based on relative standard deviation was 1.4-6.4% for intraday and 2.3-6.5% for interday analyses. Compared with previous methods, the prominent advantages of the newly developed method are simultaneous determination of pollutants with a wide range of polarities and a substantially reduced workload for ordinary environmental monitoring and food tests. Therefore, the new method has great application potential for simultaneous determination of trace pollutants with strongly contrasting polarities in several

  6. Speeding up the self-assembly of a DNA nanodevice using a variety of polar solvents

    Science.gov (United States)

    Kang, Di; Duan, Ruixue; Tan, Yerpeng; Hong, Fan; Wang, Boya; Chen, Zhifei; Xu, Shaofang; Lou, Xiaoding; Wei, Wei; Yurke, Bernard; Xia, Fan

    2014-11-01

    The specific recognition and programmable assembly properties make DNA a potential material for nanodevices. However, the more intelligent the nanodevice is, the more complicated the structure of the nanodevice is, which limits the speed of DNA assembly. Herein, to address this problem, we investigate the performance of DNA Strand Displacement Reaction (DSDR) in a mixture of polar organic solvents and aqueous buffer and demonstrate that the organic polar solvent can speed up DNA self-assembly efficiently. Taking DSDR in 20% ethanol as an example, first we have demonstrated that the DSDR is highly accelerated in the beginning of the reaction and it can complete 60% of replacement reactions (160% enhancement compared with aqueous buffer) in the first 300 seconds. Secondly, we calculated that the ΔΔG of the DSDR in 20% ethanol (-18.2 kcal mol-1) is lower than that in pure aqueous buffer (-32.6 kcal mol-1), while the activation energy is lowered by introducing ethanol. Finally, we proved that the DSDR on the electrode surface can also be accelerated using this simple strategy. More importantly, to test the efficacy of this approach in nanodevices with a complicated and slow DNA self-assembly process, we apply this strategy in the hybridization chain reaction (HCR) and prove the acceleration is fairly obvious in 20% ethanol, which demonstrates the feasibility of the proposed strategy in DNA nanotechnology and DNA-based biosensors.The specific recognition and programmable assembly properties make DNA a potential material for nanodevices. However, the more intelligent the nanodevice is, the more complicated the structure of the nanodevice is, which limits the speed of DNA assembly. Herein, to address this problem, we investigate the performance of DNA Strand Displacement Reaction (DSDR) in a mixture of polar organic solvents and aqueous buffer and demonstrate that the organic polar solvent can speed up DNA self-assembly efficiently. Taking DSDR in 20% ethanol as an

  7. In situ alcoholysis of triacylglycerols by application of switchable-polarity solvents. A new derivatization procedure for the gas-chromatographic analysis of vegetable oils.

    Science.gov (United States)

    Saliu, Francesco; Orlandi, Marco

    2013-10-01

    We describe a new use of switchable-polarity solvents for the simultaneous derivatization and extraction of triacylglycerols from vegetable oils before gas-chromatographic analysis. Different equimolecular mixtures of the commercially available amidine 1,8-diazabicyclo[5.4.0]undec-7-ene and n-alkyl alcohols were tested. Triolein was used as a model compound. Very good results were achieved by using butanol (recovery of butyl oleate was 89 ± 4%). The procedure was applied for the characterization of the fatty acid profile of different vegetable oils. No statistically significant differences from the results obtained with the application of two traditional methods were evidenced. Moreover, the use of switchable-polarity solvents showed many advantages: owing to the basicity of the amidines, no catalyst was required; the transterification reaction was conducted under mild conditions, one step and in situ; no particular matrix interferences were evidenced; the solvent was recovered.

  8. An absorbing microwave micro-solid-phase extraction device used in non-polar solvent microwave-assisted extraction for the determination of organophosphorus pesticides

    Energy Technology Data Exchange (ETDEWEB)

    Wang Ziming, E-mail: wangziming@jlu.edu.cn [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); College of Environment and Resources, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Zhao Xin; Xu Xu; Wu Lijie; Su Rui; Zhao Yajing; Jiang Chengfei; Zhang Hanqi [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Ma Qiang [Chinese Academy of Inspection and Quarantine, Beijing 100123 (China); Lu Chunmei [College of Technology Center, Jilin Entry-Exit Inspection and Quarantine Bureau, Changchun 130062 (China); Dong Deming [College of Environment and Resources, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)

    2013-01-14

    Highlights: Black-Right-Pointing-Pointer An absorbing microwave {mu}-SPE device packed with activated carbon was used. Black-Right-Pointing-Pointer Absorbing microwave {mu}-SPE device was made and used to enrich the analytes. Black-Right-Pointing-Pointer Absorbing microwave {mu}-SPE device was made and used to heat samples directly. Black-Right-Pointing-Pointer MAE-{mu}-SPE was applied to the extraction of OPPs with non-polar solvent only. - Abstract: A single-step extraction-cleanup method, including microwave-assisted extraction (MAE) and micro-solid-phase extraction ({mu}-SPE), was developed for the extraction of ten organophosphorus pesticides in vegetable and fruit samples. Without adding any polar solvent, only one kind of non-polar solvent (hexane) was used as extraction solvent in the whole extraction step. Absorbing microwave {mu}-SPE device, was prepared by packing activated carbon with microporous polypropylene membrane envelope, and used as not only the sorbent in {mu}-SPE, but also the microwave absorption medium. Some experimental parameters effecting on extraction efficiency was investigated and optimized. 1.0 g of sample, 8 mL of hexane and three absorbing microwave {mu}-SPE devices were added in the microwave extraction vessel, the extraction was carried out under 400 W irradiation power at 60 Degree-Sign C for 10 min. The extracts obtained by MAE-{mu}-SPE were directly analyzed by GC-MS without any clean-up process. The recoveries were in the range of 93.5-104.6%, and the relative standard deviations were lower than 8.7%.

  9. Co-C Dissociation of Adenosylcobalamin (Coenzyme B-12): Role of Dispersion, Induction Effects, Solvent Polarity, and Relativistic and Thermal Corrections

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta

    2014-01-01

    for dispersion, relativistic effects, solvent polarity, basis set superposition error, and thermal and vibrational effects were investigated, totaling more than SSO single-point energies for the large model. The results show immense variability depending on method, including solvation, functional type...

  10. Electro-responsivity of ionic liquid boundary layers in a polar solvent revealed by neutron reflectance

    Science.gov (United States)

    Pilkington, Georgia A.; Harris, Kathryn; Bergendal, Erik; Reddy, Akepati Bhaskar; Palsson, Gunnar K.; Vorobiev, Alexei; Antzutkin, Oleg. N.; Glavatskih, Sergei; Rutland, Mark W.

    2018-05-01

    Using neutron reflectivity, the electro-responsive structuring of the non-halogenated ionic liquid (IL) trihexyl(tetradecyl)phosphonium-bis(mandelato)borate, [P6,6,6,14][BMB], has been studied at a gold electrode surface in a polar solvent. For a 20% w/w IL mixture, contrast matched to the gold surface, distinct Kiessig fringes were observed for all potentials studied, indicative of a boundary layer of different composition to that of the bulk IL-solvent mixture. With applied potential, the amplitudes of the fringes from the gold-boundary layer interface varied systematically. These changes are attributable to the differing ratios of cations and anions in the boundary layer, leading to a greater or diminished contrast with the gold electrode, depending on the individual ion scattering length densities. Such electro-responsive changes were also evident in the reflectivities measured for the pure IL and a less concentrated (5% w/w) IL-solvent mixture at the same applied potentials, but gave rise to less pronounced changes. These measurements, therefore, demonstrate the enhanced sensitivity achieved by contrast matching the bulk solution and that the structure of the IL boundary layers formed in mixtures is strongly influenced by the bulk concentration. Together these results represent an important step in characterising IL boundary layers in IL-solvent mixtures and provide clear evidence of electro-responsive structuring of IL ions in their solutions with applied potential.

  11. Substituent and solvent effects on spectroscopic properties of 2-amino-1,3-dicyano-5,6,7,8-tetrahydronaphthalene derivatives

    International Nuclear Information System (INIS)

    Józefowicz, M.; Bajorek, A.; Pietrzak, M.; Heldt, J.R.; Heldt, J.

    2014-01-01

    In this article, we report the photophysical properties of six, newly synthesized donor-substituted 2-amino-1,3-dicyano-5,6,7,8-tetrahydronaphthalene fluorophores. The steady-state and time-resolved spectroscopic experiments have been used to investigate the substituent and solvent effects on the locally excited (LE) and intramolecular charge transfer (ICT) emission. We demonstrate that the spectroscopic characteristics (fluorescence quantum yields, fluorescence decay times, radiative rate constants, and ground and excited state dipole moments) of the studied D–A dyes, as well as the reorganization energies characterizing the solute–solvent interactions and intramolecular torsion motions greatly depend on different substituents and microenvironment. On the basis of the experimental results and our previous quantum-chemical calculations, it was shown that two emitting charge transfer states: non-relaxed (ICT) NR and relaxed (ICT) R exist in six biphenyl derivatives dissolved in polar solvents (e.g., THF), whereas in non-polar medium (MCH) the existence of two emissive states have been attributed to non-relaxed and relaxed, locally excited state ((LE) NR , (LE) R ). - Highlights: • Spectroscopic properties greatly depend on different substituents and microenvironment. • Investigated dyes form a typically spectrally inhomogeneous system. • Two emitting charge transfer states (ICT) NR and (ICT) R exist in polar solvents. • In non-polar medium locally excited fluorescence is possible from (LE) NR and (LE) R states

  12. Effect of dynamic surface polarization on the oxidative stability of solvents in nonaqueous Li-O 2 batteries

    Science.gov (United States)

    Khetan, Abhishek; Pitsch, Heinz; Viswanathan, Venkatasubramanian

    2017-09-01

    Polarization-induced renormalization of the frontier energy levels of interacting molecules and surfaces can cause significant shifts in the excitation and transport behavior of electrons. This phenomenon is crucial in determining the oxidative stability of nonaqueous electrolytes in high-energy density electrochemical systems such as the Li-O2 battery. On the basis of partially self-consistent first-principles Sc G W0 calculations, we systematically study how the electronic energy levels of four commonly used solvent molecules, namely, dimethylsulfoxide (DMSO), dimethoxyethane (DME), tetrahydrofuran (THF), and acetonitrile (ACN), renormalize when physisorbed on the different stable surfaces of Li2O2 , the main discharge product. Using band level alignment arguments, we propose that the difference between the solvent's highest occupied molecular orbital (HOMO) level and the surface's valence-band maximum (VBM) is a refined metric of oxidative stability. This metric and a previously used descriptor, solvent's gas phase HOMO level, agree quite well for physisorbed cases on pristine surfaces where ACN is oxidatively most stable followed by DME, THF, and DMSO. However, this effect is intrinsically linked to the surface chemistry of the solvent's interaction with the surface states and defects, and depends strongly on their nature. We conclusively show that the propensity of solvent molecules to oxidize will be significantly higher on Li2O2 surfaces with defects as compared to pristine surfaces. This suggests that the oxidative stability of a solvent is dynamic and is a strong function of surface electronic properties. Thus, while gas phase HOMO levels could be used for preliminary solvent candidate screening, a more refined picture of solvent stability requires mapping out the solvent stability as a function of the state of the surface under operating conditions.

  13. Nitrobenzene anti-parallel dimer formation in non-polar solvents

    Directory of Open Access Journals (Sweden)

    Toshiyuki Shikata

    2014-06-01

    Full Text Available We investigated the dielectric and depolarized Rayleigh scattering behaviors of nitrobenzene (NO2-Bz, which is a benzene mono-substituted with a planar molecular frame bearing the large electric dipole moment 4.0 D, in non-polar solvents solutions, such as tetrachloromethane and benzene, at up to 3 THz for the dielectric measurements and 8 THz for the scattering experiments at 20 °C. The dielectric relaxation strength of the system was substantially smaller than the proportionality to the concentration in a concentrated regime and showed a Kirkwood correlation factor markedly lower than unity; gK ∼ 0.65. This observation revealed that NO2-Bz has a tendency to form dimers, (NO2-Bz2, in anti-parallel configurations for the dipole moment with increasing concentration of the two solvents. Both the dielectric and scattering data exhibited fast and slow Debye-type relaxation modes with the characteristic time constants ∼7 and ∼50 ps in a concentrated regime (∼15 and ∼30 ps in a dilute regime, respectively. The fast mode was simply attributed to the rotational motion of the (monomeric NO2-Bz. However, the magnitude of the slow mode was proportional to the square of the concentration in the dilute regime; thus, the mode was assigned to the anti-parallel dimer, (NO2-Bz2, dissociation process, and the slow relaxation time was attributed to the anti-parallel dimer lifetime. The concentration dependencies of both the dielectric and scattering data show that the NO2-Bz molecular processes are controlled through a chemical equilibrium between monomers and anti-parallel dimers, 2NO2-Bz ↔ (NO2-Bz2, due to a strong dipole-dipole interaction between nitro groups.

  14. General Solvent-dependent Strategy toward Enhanced Oxygen Reduction Reaction in Graphene/Metal Oxide Nanohybrids: Effects of Nitrogen-containing Solvent

    Science.gov (United States)

    Kao, Wei-Yao; Chen, Wei-Quan; Chiu, Yu-Hsiang; Ho, Yu-Hsuan; Chen, Chun-Hu

    2016-11-01

    A general solvent-dependent protocol directly influencing the oxygen reduction reaction (ORR) in metal oxide/graphene nanohybrids has been demonstrated. We conducted the two-step synthesis of cobalt oxide/N-doped graphene nanohybrids (CNG) with solvents of water, ethanol, and dimethylformamide (DMF), representing tree typical categories of aqueous, polar organic, and organic N-containing solvents commonly adopted for graphene nanocomposites preparation. The superior ORR performance of the DMF-hybrids can be attributed to the high nitrogen-doping, aggregation-free hybridization, and unique graphene porous structures. As DMF is the more effective N-source, the spectroscopic results support a catalytic nitrogenation potentially mediated by cobalt-DMF coordination complexes. The wide-distribution of porosity (covering micro-, meso-, to macro-pore) and micron-void assembly of graphene may further enhance the diffusion kinetics for ORR. As the results, CNG by DMF-synthesis exhibits the high ORR activities close to Pt/C (i.e. only 8 mV difference of half-wave potential with electron transfer number of 3.96) with the better durability in the alkaline condition. Additional graphene hybrids comprised of iron and manganese oxides also show the superior ORR activities by DMF-synthesis, confirming the general solvent-dependent protocol to achieve enhanced ORR activities.

  15. Preferential solvation of fluorenone and 4-hydroxyfluorenone in binary solvent mixtures

    International Nuclear Information System (INIS)

    Jozefowicz, Marek; Heldt, Janina R.

    2003-01-01

    Preferential solvation of fluorenone and 4-hydroxyfluorenone in binary solvent mixtures has been studied using steady-state spectroscopic measurements. This study concerns the solvent-induced shift of the absorption and fluorescence spectra of both molecules in two solvent mixtures, i.e., cyclohexane-tetrahydrofuran and cyclohexane-ethanol. The first system contains polar solute molecules, fluorenone and 4-hydroxyfluorenone, in a mixture of polar aprotic (tetrahydrofuran) and non-polar (cyclohexane) solvents. In the second solvents mixture, hydrogen bonding with solute molecules (ethanol) may occur. The results of spectroscopic measurements are analysed using theoretical models of Bakshiev, Mazurenko and Suppan which describe preferential solvation phenomena. In the case of cyclohexane-tetrahydrofuran mixtures, the deviation from linearity in the absorption and fluorescence solvatochromic shifts vs. the solution polarity is due to non-specific dipolar solvent-solute interactions. For cyclohexane-ethanol binary mixtures, both non-specific and specific (hydrogen bond and proton-relay tautomerization) interactions contribute to the observed solvatochromism

  16. Photoinduced electron transfer in covalent ruthenium-anthraquinone dyads: relative importance of driving-force, solvent polarity, and donor-bridge energy gap.

    Science.gov (United States)

    Hankache, Jihane; Wenger, Oliver S

    2012-02-28

    Four rigid rod-like molecules comprised of a Ru(bpy)(3)(2+) (bpy = 2,2'-bipyridine) photosensitizer, a 9,10-anthraquinone electron acceptor, and a molecular bridge connecting the two redox partners were synthesized and investigated by optical spectroscopic and electrochemical means. An attempt was made to assess the relative importance of driving-force, solvent polarity, and bridge variation on the rates of photoinduced electron transfer in these molecules. Expectedly, introduction of tert-butyl substituents in the bipyridine ligands of the ruthenium complex and a change in solvent from dichloromethane to acetonitrile lead to a significant acceleration of charge transfer rates. In dichloromethane, photoinduced electron transfer is not competitive with the inherent excited-state deactivation processes of the photosensitizer. In acetonitrile, an increase in driving-force by 0.2 eV through attachment of tert-butyl substituents to the bpy ancillary ligands causes an increase in electron transfer rates by an order of magnitude. Replacement of a p-xylene bridge by a p-dimethoxybenzene spacer entails an acceleration of charge transfer rates by a factor of 3.5. In the dyads from this study, the relative order of importance of individual influences on electron transfer rates is therefore as follows: solvent polarity ≥ driving-force > donor-bridge energy gap.

  17. An absorbing microwave micro-solid-phase extraction device used in non-polar solvent microwave-assisted extraction for the determination of organophosphorus pesticides.

    Science.gov (United States)

    Wang, Ziming; Zhao, Xin; Xu, Xu; Wu, Lijie; Su, Rui; Zhao, Yajing; Jiang, Chengfei; Zhang, Hanqi; Ma, Qiang; Lu, Chunmei; Dong, Deming

    2013-01-14

    A single-step extraction-cleanup method, including microwave-assisted extraction (MAE) and micro-solid-phase extraction (μ-SPE), was developed for the extraction of ten organophosphorus pesticides in vegetable and fruit samples. Without adding any polar solvent, only one kind of non-polar solvent (hexane) was used as extraction solvent in the whole extraction step. Absorbing microwave μ-SPE device, was prepared by packing activated carbon with microporous polypropylene membrane envelope, and used as not only the sorbent in μ-SPE, but also the microwave absorption medium. Some experimental parameters effecting on extraction efficiency was investigated and optimized. 1.0 g of sample, 8 mL of hexane and three absorbing microwave μ-SPE devices were added in the microwave extraction vessel, the extraction was carried out under 400 W irradiation power at 60°C for 10 min. The extracts obtained by MAE-μ-SPE were directly analyzed by GC-MS without any clean-up process. The recoveries were in the range of 93.5-104.6%, and the relative standard deviations were lower than 8.7%. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Scanning force microscopy study of phase segregation in fuel cell membrane materials as a function of solvent polarity and relative humidity

    Energy Technology Data Exchange (ETDEWEB)

    Hawley, Marilyn Emily [Los Alamos National Laboratory; Kim, Yu S [Los Alamos National Laboratory; Hjelm, Rex P [Los Alamos National Laboratory

    2010-01-01

    Scanning force microscopy (SFM) phase imaging provides a powerful method for directly studying and comparing phase segregation in fuel cell membrane materials due to different preparation and under different temperature and hwnidity exposures. In this work, we explored two parameters that can influence phase segregation: the properties of the solvents used in casting membrane films and how these solvents alter phase segregation after exposure to boiling water as a function of time. SFM was used under ambient conditions to image phase segregation in Nafion samples prepared using five different solvents. Samples were then subjected to water vapor maintained at 100C for periods ranging from 30 minutes to three hours and re-imaged using the same phase imaging conditions. SFM shows what appears to be an increase in phase segregation as a function of solvent polarity that changes as a function of water exposure.

  19. Solvent jet desorption capillary photoionization-mass spectrometry.

    Science.gov (United States)

    Haapala, Markus; Teppo, Jaakko; Ollikainen, Elisa; Kiiski, Iiro; Vaikkinen, Anu; Kauppila, Tiina J; Kostiainen, Risto

    2015-03-17

    A new ambient mass spectrometry method, solvent jet desorption capillary photoionization (DCPI), is described. The method uses a solvent jet generated by a coaxial nebulizer operated at ambient conditions with nitrogen as nebulizer gas. The solvent jet is directed onto a sample surface, from which analytes are extracted into the solvent and ejected from the surface in secondary droplets formed in collisions between the jet and the sample surface. The secondary droplets are directed into the heated capillary photoionization (CPI) device, where the droplets are vaporized and the gaseous analytes are ionized by 10 eV photons generated by a vacuum ultraviolet (VUV) krypton discharge lamp. As the CPI device is directly connected to the extended capillary inlet of the MS, high ion transfer efficiency to the vacuum of MS is achieved. The solvent jet DCPI provides several advantages: high sensitivity for nonpolar and polar compounds with limit of detection down to low fmol levels, capability of analyzing small and large molecules, and good spatial resolution (250 μm). Two ionization mechanisms are involved in DCPI: atmospheric pressure photoionization, capable of ionizing polar and nonpolar compounds, and solvent assisted inlet ionization capable of ionizing larger molecules like peptides. The feasibility of DCPI was successfully tested in the analysis of polar and nonpolar compounds in sage leaves and chili pepper.

  20. Gas separation by composite solvent-swollen membranes

    Science.gov (United States)

    Matson, Stephen L.; Lee, Eric K. L.; Friesen, Dwayne T.; Kelly, Donald J.

    1989-01-01

    There is disclosed a composite immobulized liquid membrane of a solvent-swollen polymer and a microporous organic or inorganic support, the solvent being at least one highly polar solvent containing at least one nitrogen, oxygen, phosphorous or sulfur atom, and having a boiling point of at least 100.degree. C. and a specified solubility parameter. The solvent or solvent mixture is homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. The membrane is suitable for acid gas scrubbing and oxygen/nitrogen separation.

  1. Gas separation by composite solvent-swollen membranes

    Science.gov (United States)

    Matson, S.L.; Lee, E.K.L.; Friesen, D.T.; Kelly, D.J.

    1989-04-25

    There is disclosed a composite immobilized liquid membrane of a solvent-swollen polymer and a microporous organic or inorganic support, the solvent being at least one highly polar solvent containing at least one nitrogen, oxygen, phosphorus or sulfur atom, and having a boiling point of at least 100 C and a specified solubility parameter. The solvent or solvent mixture is homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. The membrane is suitable for acid gas scrubbing and oxygen/nitrogen separation. 3 figs.

  2. Organic solvents improve hydrocarbon desorption and biodegradation in highly contaminated weathered soils

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Rivero, M. [Tecnologico de Estudios Superiores de Ecatepec, Mexico City (Mexico); Saucedo-Casteneda, G.; Gutierrez-Rojas, M. [Autonoma Metropolitan Univ., Mexico City (Mexico). Dept. of Biotechnology

    2007-07-15

    A toluene-based microbial slurry phase system was used to remediate hydrocarbons (HC) in highly contaminated soil samples collected from a site next to a working refinery in Mexico. Initial HC concentrations of the samples were 237.2 {+-} 16,6 g kg{sup -1} in dry soil. The microbial consortium consisted of 10 different strains in a mineral solution. Non-polar solvents used in the phase system included hexane, benzene, and toluene. Polar solvents included n-butanol, acetone, and methanol. The bioavailability of the HCs was increased using both polar and nonpolar solvents in order to promote desorption from the soil and to enhance overall HC biodegradation. HC desorption was analyzed in an abiotic system. Respiration and residual HCs were examined after a period of 30 days in order to compare the effects of the 2 solvents. The biodegradation extracts were then fractionated in a silica gel column to determine if the solvents actually enhanced the biodegradation of specific HC fractions. The study showed that induced dipole interactions forces resulted when nonpolar molecules were dissolved into a nonpolar solvent. Results for desorption and solubility varied among the 6 solvents. Higher dielectric constants resulted in higher solubility and desorption of HCs for nonpolar solvents, while the opposite effect was observed for polar solvents. It was concluded that toluene produced better biodegradation results than any of the milder solvents. 34 refs., 4 tabs., 1 fig.

  3. Stability of the solid electrolyte Li{sub 3}OBr to common battery solvents

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, D.J. [Department of Engineering Technology, College of Engineering and Engineering Technology, Northern Illinois University, 301B Still Gym, DeKalb, IL 60115 (United States); Hubaud, A.A. [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439-4837 (United States); Vaughey, J.T., E-mail: vaughey@anl.gov [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439-4837 (United States)

    2014-01-01

    Graphical abstract: The stability of the anti-perovskite phase Li{sub 3}OBr has been assessed in a variety of battery solvents. - Highlights: • Lithium stable solid electrolyte Li{sub 3}OBr unstable to polar organic solvents. • Solvation with no dissolution destroys long-range structure. • Ion exchange with protons observed. - Abstract: Recently a new class of solid lithium ion conductors was reported based on the anti-perovskite structure, notably Li{sub 3}OCl and Li{sub 3}OBr. For many beyond lithium-ion battery uses, the solid electrolyte is envisioned to be in direct contact with liquid electrolytes and lithium metal. In this study we evaluated the stability of the Li{sub 3}OBr phase against common battery solvents electrolytes, including diethylcarbonate (DEC) and dimethylcarbonate (DMC), as well as a LiPF{sub 6} containing commercial electrolyte. In contact with battery-grade organic solvents, Li{sub 3}OBr was typically found to be insoluble but lost its crystallinity and reacted with available protons and in some cases with the solvent. A low temperature heat treatment was able to restore crystallinity of the samples; however evidence of proton ion exchange was conserved.

  4. Catalyst of a metal heteropoly acid salt that is insoluble in a polar solvent on a non-metallic porous support and method of making

    Science.gov (United States)

    Wang, Yong [Richland, WA; Peden, Charles H. F. [West Richland, WA; Choi, Saemin [Richland, WA

    2002-10-29

    The present invention includes a catalyst having (a) a non-metallic support having a plurality of pores; (b) a metal heteropoly acid salt that is insoluble in a polar solvent on the non-metallic support; wherein at least a portion of the metal heteropoly acid salt is dispersed within said plurality of pores. The present invention also includes a method of depositing a metal heteropoly acid salt that is insoluble in a polar solvent onto a non-metallic support having a plurality of pores. The method has the steps of: (a) obtaining a first solution containing a first precursor of a metal salt cation; (b) obtaining a second solution containing a second precursor of a heteropoly acid anion in a solvent having a limited dissolution potential for said first precursor; (c) impregnating the non-metallic support with the first precursor forming a first precursor deposit within the plurality of pores, forming a first precursor impregnated support; (d) heating said first precursor impregnated support forming a bonded first precursor impregnated support; (e) impregnating the second precursor that reacts with the precursor deposit and forms the metal heteropoly acid salt.

  5. Solvent-dependent fluorescence enhancement and piezochromism of a carbazole-substituted naphthopyran

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lihui; Wang, Aixia [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China); Wang, Guang, E-mail: wangg923@nenu.edu.cn [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China); Munyentwari, Alexis [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China); Zhou, Yihan, E-mail: yhzhou@ciac.ac.cn [National Analytical Research Center of Electrochemistry and Spectroscopy, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2015-09-15

    A novel carbazole-substituted naphthopyran, 3,3-bis-(4-carbazolylphenyl)-[3H]-naphtho[2,1-b]pyran (CzNP) was designed and synthesized. The new compound exhibited normal photochromism in dichloromethane solution and the UV irradiation did not influence its fluorescence. On the contrary, the fluorescence of CzNP in N,N-dimethylformamide (DMF) was intensively enhanced to 29 times after 60 min of the UV irradiation and this enhanced fluorescence can be quenched by addition of triethylamine (TEA). The study of enhanced extent of fluorescence of CzNP in solvents with different polarities and in mixed solvents demonstrated that the enhanced fluorescence is dependent on the polarity of solvents. The larger the polarity of solvent was, the stronger was the fluorescence of CzNP. CzNP also exhibited piezochromic performance and the pressure led to the cleavage of the C–O bond of pyran ring. - Highlights: • A carbazole-substituted photochromic naphthopyran was designed and synthesized. • The fluorescence was enhanced under the existence of DMF and UV irradiation. • The polarity of solvent was the dominating factor to affect the fluorescence. • The new compound also displayed piezochromic performance.

  6. Vegetable Oils as Alternative Solvents for Green Oleo-Extraction, Purification and Formulation of Food and Natural Products.

    Science.gov (United States)

    Yara-Varón, Edinson; Li, Ying; Balcells, Mercè; Canela-Garayoa, Ramon; Fabiano-Tixier, Anne-Sylvie; Chemat, Farid

    2017-09-05

    Since solvents of petroleum origin are now strictly regulated worldwide, there is a growing demand for using greener, bio-based and renewable solvents for extraction, purification and formulation of natural and food products. The ideal alternative solvents are non-volatile organic compounds (VOCs) that have high dissolving power and flash point, together with low toxicity and less environmental impact. They should be obtained from renewable resources at a reasonable price and be easy to recycle. Based on the principles of Green Chemistry and Green Engineering, vegetable oils could become an ideal alternative solvent to extract compounds for purification, enrichment, or even pollution remediation. This review presents an overview of vegetable oils as solvents enriched with various bioactive compounds from natural resources, as well as the relationship between dissolving power of non-polar and polar bioactive components with the function of fatty acids and/or lipid classes in vegetable oils, and other minor components. A focus on simulation of solvent-solute interactions and a discussion of polar paradox theory propose a mechanism explaining the phenomena of dissolving polar and non-polar bioactive components in vegetable oils as green solvents with variable polarity.

  7. Tipping Point for Expansion of Layered Aluminosilicates in Weakly Polar Solvents: Supercritical CO 2

    Energy Technology Data Exchange (ETDEWEB)

    Schaef, Herbert T.; Loganathan, Narasimhan; Bowers, Geoffrey M.; Kirkpatrick, Robert J.; Yazaydin, A. O.; Burton, Sarah D.; Hoyt, David W.; Thanthiriwatte, Sahan; Dixon, David A.; McGrail, Bernard P.; Rosso, Kevin M.; Ilton, Eugene S.; Loring, John S.

    2017-10-11

    Layered aluminosilicates play a dominant role in the mechanical and gas storage properties of the subsurface, are used in diverse industrial applications, and serve as model materials for understanding solvent-ion-support systems. Although expansion in the presence of H2O is well known to be systematically correlated with the hydration free energy of the interlayer cation, in environments dominated by non-polar solvents (i.e. CO2), uptake into the interlayer is not well-understood. Using novel high pressure capabilities, we investigated the interaction of super-critical CO2 with Na+-, NH4+-, and Cs+-saturated montmorillonite, comparing results with predictions from molecular dynamics simulations. Despite the known trend in H2O, and that cation solvation energies in CO2 suggest a stronger interaction with Na+, both the NH4+- and Cs+-clays readily absorbed CO2 and expanded while the Na+-clay did not. The apparent inertness of the Na+-clay was not due to kinetics, as experiments seeking a stable expanded state showed that none exists. Molecular dynamics simulations revealed a large endothermicity to CO2 intercalation in the Na+-clay, but little or no energy barrier for the NH4+- and Cs+-clays. Consequently, we have shown for the first time that in the presence of a low dielectric constant gas swelling depends more on the strength of the interaction between interlayer cation and aluminosilicate sheets and less on that with solvent. The finding suggests a distinct regime in layered aluminosilicates swelling behavior triggered by low solvent polarizability, with important implications in geomechanics, storage and retention of volatile gases, and across industrial uses in gelling, decoloring, heterogeneous catalysis, and semi-permeable reactive barriers.

  8. Influence of anion on thermophysical properties of ionic liquids with polar solvent

    International Nuclear Information System (INIS)

    Govinda, Varadhi; Reddy, P. Madhusudhana; Attri, Pankaj; Venkatesu, P.; Venkateswarlu, P.

    2013-01-01

    Highlights: ► We have reported a series of ionic liquids (ILs) involving a common cation. ► The molecular interactions between ILs and DMSO. ► The results for observed anion dependent phenomena. ► Redlich–Kister polynomial was used to correlate the results. ► The intermolecular interactions were analyzed on the basis of properties. -- Abstract: In this work, we have reported a series of ionic liquids (ILs) involving a common cation trimethyl ammonium, ([(CH 3 ) 3 NH] + ), with generally used anions (acetate, [CH 3 COO] − , sulfate, [HSO 4 ] − , phosphate, [H 2 PO 4 ] − ). To address the molecular interactions between the relatively new class of solvents such as trimethylammonium acetate [(CH 3 ) 3 NH + ] [CH 3 COO – ] (TMAA), trimethylammonium hydrogen sulfate [(CH 3 ) 3 NH + ][HSO 4 − ] (TMAS), and trimethylammonium dihydrogen phosphate [(CH 3 ) 3 NH + ][H 2 PO 4 – ] (TMAP), with the polar solvent, dimethylsulfoxide (DMSO), the density (ρ), speed of sound (u) and viscosity (η) values have been measured over complete concentration range and wide temperature range from 298.15 K to 313.15 K in steps of 5 K under ambient pressure. By using these experimental results, excess volumes (V E ), isentropic compressibility deviations (Δκ s ) and viscosity deviations (Δη) were obtained for all these binary systems at all experimental temperatures. The results are correlated by the Redlich−Kister type function to derive the coefficients and estimate the standard error. Further, the results for observed anion dependent phenomena and temperature influence on measured and derived properties are also discussed

  9. Acetone-based cellulose solvent.

    Science.gov (United States)

    Kostag, Marc; Liebert, Tim; Heinze, Thomas

    2014-08-01

    Acetone containing tetraalkylammonium chloride is found to be an efficient solvent for cellulose. The addition of an amount of 10 mol% (based on acetone) of well-soluble salt triethyloctylammonium chloride (Et3 OctN Cl) adjusts the solvent's properties (increases the polarity) to promote cellulose dissolution. Cellulose solutions in acetone/Et3 OctN Cl have the lowest viscosity reported for comparable aprotic solutions making it a promising system for shaping processes and homogeneous chemical modification of the biopolymer. Recovery of the polymer and recycling of the solvent components can be easily achieved. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Solvent induced supramolecular anisotropy in molecular gels

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Michael A., E-mail: mroger09@uoguelph.ca [Department of Food Science, University of Guelph, Guelph, Ontario, N3C3X9 (Canada); Corradini, Maria G. [Department of Food Science, University of Massachusetts Amherst, Amherst, MA, 01003 (United States); Emge, Thomas [Department of Chemistry and Biochemistry, Rutgers University, New Brunswick, NJ, 08901 (United States)

    2017-06-15

    Herein is the first report of solvent induced anisotropy in 12-hydroxystearic acid self-assembled fibrillar networks. Increasing the chain length of polar solvent, such as nitriles and ketones, tailored the anisotropy of the fibrillar aggregates. 12HSA molecular gels, comprised of alkanes, exhibited an isotropic fibrillar network irrespective of the alkane chain length. In polar solvents, anisotropy, observed using 2D powder x-ray diffraction profiles, is correlated to a fibrillar supramolecular morphologies in long chain nitriles and ketones while sphereulitic crystals are correlated to x-ray diffraction patterns with an isotropic scatter intensity in short chain ketones and nitriles. These changes directly modify the final physical properties of the gels. - Highlights: • 12-HSA self-assembles into crystalline supramolecular morphologies depending on the solvent. • Alkanes, short chain nitriles and ketones led to 12-HSA displaying supramolecular isotropy. • In long chain nitriles and ketones, 12-HSA displays supramolecular anisotropy.

  11. Solvent induced supramolecular anisotropy in molecular gels

    International Nuclear Information System (INIS)

    Rogers, Michael A.; Corradini, Maria G.; Emge, Thomas

    2017-01-01

    Herein is the first report of solvent induced anisotropy in 12-hydroxystearic acid self-assembled fibrillar networks. Increasing the chain length of polar solvent, such as nitriles and ketones, tailored the anisotropy of the fibrillar aggregates. 12HSA molecular gels, comprised of alkanes, exhibited an isotropic fibrillar network irrespective of the alkane chain length. In polar solvents, anisotropy, observed using 2D powder x-ray diffraction profiles, is correlated to a fibrillar supramolecular morphologies in long chain nitriles and ketones while sphereulitic crystals are correlated to x-ray diffraction patterns with an isotropic scatter intensity in short chain ketones and nitriles. These changes directly modify the final physical properties of the gels. - Highlights: • 12-HSA self-assembles into crystalline supramolecular morphologies depending on the solvent. • Alkanes, short chain nitriles and ketones led to 12-HSA displaying supramolecular isotropy. • In long chain nitriles and ketones, 12-HSA displays supramolecular anisotropy.

  12. 40 CFR Table 4 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction... formulation data. Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical organic HAP, percent...

  13. 40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the... Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical organic HAP, percent by mass 1...

  14. 40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the.... Solvent/solvent blend CAS. No. Average organic HAP mass fraction Typical organic HAP, percent by mass 1...

  15. Kinetic isotope effects and tunnelling in the proton-transfer reaction between 4-nitrophenylnitromethane and tetramethylguanidine in various aprotic solvents

    International Nuclear Information System (INIS)

    Caldin, E.F.; Mateo, S.

    1975-01-01

    Rates and equilibrium constants have been determined for the proton-transfer reaction of 4-nitrophenylnitromethane, NO 2 C 6 H 4 CH 2 NO 2 , and its αα-deuterated analogue NO 2 C 6 H 4 CD 2 NO 2 , with the strong base tetramethylguanidine [HN=C(NMe 2 ) 2 ), at temperatures between -60 0 C and +65 0 in a range of aprotic solvents. Spectrophotometry and the stopped-flow technique were used. The reaction is a simple proton-transfer process leading to an ion-pair. The kinetic isotope effects are correlated with the polarity of the solvents, as measured by the dielectric constant or by the empirical parameter Esub(T). In the less polar solvents they are exceptionally large. In toluene, for example, at 25 0 C the rate ratio ksup(H)/ksup(D) = 45 +- 2, the activation energy difference Esub(a)sup(D) - Esub(a)sup(H) =4.3 +- 0.3 kcal molsup(-1) (16 kJ molsup(-1), and the ratio of the pre-exponential factors logsub(10) (Asup(D)/Asup(H)) = 1.5 +- 0.2+ and even larger values of logsub(10)(Asup(D)/Asup(H)) are found for mesitylene (1.94 +- 0.06) and cyclohexane (2.4 +- 0.2). Positive deviations from linear Arrhenius plots are found for these solvents. Tunnelling is the only interpretation that cannot account for these results. For the more polar solvents (dielectric constant 7 to 37), the isotope effects are closer to the range predicted by semi-classical theory. The isotope effects in all solvents have been fitted to Bell's equation for a parabolic barrier, and the barrier dimensions calculated for each solvent. The suggested interpretation of the results is that the solvent-solute interactions affect the height of the barrier and that motions of solvent molecules are coupled with the motion of the proton in the more polar solvents but not in the less polar ones; reorganization of solvent molecules accompanies the proton-transfer in the more polar solvents, but only electron-polarization in the less polar. Tunnelling has large effects in the less polar solvents, where the

  16. Spectroscopic and DFT study of solvent effects on the electronic absorption spectra of sulfamethoxazole in neat and binary solvent mixtures

    Science.gov (United States)

    Almandoz, M. C.; Sancho, M. I.; Blanco, S. E.

    2014-01-01

    The solvatochromic behavior of sulfamethoxazole (SMX) was investigated using UV-vis spectroscopy and DFT methods in neat and binary solvent mixtures. The spectral shifts of this solute were correlated with the Kamlet and Taft parameters (α, β and π*). Multiple lineal regression analysis indicates that both specific hydrogen-bond interaction and non specific dipolar interaction play an important role in the position of the absorption maxima in neat solvents. The simulated absorption spectra using TD-DFT methods were in good agreement with the experimental ones. Binary mixtures consist of cyclohexane (Cy)-ethanol (EtOH), acetonitrile (ACN)-dimethylsulfoxide (DMSO), ACN-dimethylformamide (DMF), and aqueous mixtures containing as co-solvents DMSO, ACN, EtOH and MeOH. Index of preferential solvation was calculated as a function of solvent composition and non-ideal characteristics are observed in all binary mixtures. In ACN-DMSO and ACN-DMF mixtures, the results show that the solvents with higher polarity and hydrogen bond donor ability interact preferentially with the solute. In binary mixtures containing water, the SMX molecules are solvated by the organic co-solvent (DMSO or EtOH) over the whole composition range. Synergistic effect is observed in the case of ACN-H2O and MeOH-H2O, indicating that at certain concentrations solvents interact to form association complexes, which should be more polar than the individual solvents of the mixture.

  17. Exfoliation of graphite into graphene in polar solvents mediated by amphiphilic hexa-peri-hexabenzocoronene.

    Science.gov (United States)

    Kabe, Ryota; Feng, Xinliang; Adachi, Chihaya; Müllen, Klaus

    2014-11-01

    A water-soluble surfactant consisting of hexa-peri-hexabenzocoronene (HBC) as hydrophobic aromatic core and hydrophilic carboxy substituents was synthesized. It exhibited a self-assembled nanofiber structure in the solid state. Profiting from the π interactions between the large aromatic core of HBC and graphene, the surfactant mediated the exfoliation of graphite into graphene in polar solvents, which was further stabilized by the bulky hydrophilic carboxylic groups. A graphene dispersion with a concentration as high as 1.1 mg L(-1) containing 2-6 multilayer nanosheets was obtained. The lateral size of the graphene sheets was in the range of 100-500 nm based on atomic force microscope (AFM) and transmission electron microscope (TEM) measurements. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Solvent Optimization for Efficient Enzymatic Monoacylglycerol Production Based on a Glycerolysis Reaction

    DEFF Research Database (Denmark)

    Damstrup, Marianne; Jensen, Tine; Sparsø, Flemming V.

    2005-01-01

    This study was aimed at screening solvent systems of varying polarities to identify suitable solvents for efficient and practical enzymatic glycerolysis. Several pure solvents and solvent mixtures were screened in a batch reaction system consisting of glycerol, sunflower oil, and Novozymo (R) 435...

  19. Solvent Dependency of the UV-Vis Spectrum of Indenoisoquinolines: Role of Keto-Oxygens as Polarity Interaction Probes

    Science.gov (United States)

    Coletta, Andrea; Castelli, Silvia; Chillemi, Giovanni; Sanna, Nico; Cushman, Mark; Pommier, Yves; Desideri, Alessandro

    2013-01-01

    Indenoisoquinolines are the most promising non-campthotecins topoisomerase IB inhibitors. We present an integrated experimental/computational investigation of the UV-Vis spectra of the IQNs parental compound (NSC314622) and two of its derivatives (NSC724998 and NSC725776) currently undergoing Phase I clinical trials. In all the three compounds a similar dependence of the relative absorption intensities at 270 nm and 290 nm on solvent polarity is found. The keto-oxygens in positions 5 and 11 of the molecular scaffold of the molecule are the principal chromophores involved in this dependence. Protic interactions on these sites are also found to give rise to absorptions at wavelength <250 nm observed in water solution, due to the stabilization of highly polarized tautomers of the molecule. These results suggest that the keto-oxygens are important polarizable groups that can act as useful interactors with the molecular receptor, providing at the same time an useful fingerprint for the monitoring of the drug binding to topoisomerase IB. PMID:24086299

  20. Solvents effects on crystallinity and dissolution of β-artemether.

    Science.gov (United States)

    Xu, Jianghui; Singh, Vikramjeet; Yin, Xianzhen; Singh, Parbeen; Wu, Li; Xu, Xiaonan; Guo, Tao; Sun, Lixin; Gui, Shuangying; Zhang, Jiwen

    2017-03-01

    β-artemether (ARM) is a widely used anti-malarial drug isolated from the Chinese antimalarial plant, Artemisia annua. The solvent effects on crystal habits and dissolution of ARM were thoroughly investigated and discussed herein. The ARM was recrystallized in nine different solvents of varied polarity, namely, methanol, ethanol, isopropanol, tetrahydrofuran, dichloromethane, trichloromethane, ethyl acetate, acetone and hexane by solvent evaporation method. The obtained crystals were morphologically characterized using scanning electron microscope (SEM). The average sizes of crystals were 1.80-2.64 μm calculated from microscopic images using Image-Pro software. No significant change in chemical structure was noticed after recrystallization and the specific band at 875 cm -1 wavenumber (C-O-O-C) confirmed the presence of most sensitive functional group in the ARM chemical structure. The existence and production of two polymorphic forms, polymorph A and polymorph B, was confirmed by differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). The data suggested that the fabrication of polymorph B can be simply obtained from the recrystallization of ARM in a specific solvent. Significant effects of solvent polarity, crystals shapes and sizes on drug dissolution were noticed during in vitro dissolution test. The release kinetics were calculated and well fitted by the Higuchi and Hixon-Crowell models. The ARM-methanol and ARM-hexane showed highest and slowest dissolution, respectively, due to the effects of solvent polarity and crystal morphologies. Overall, proper selection of the solvents for the final crystallization of ARM helps to optimize dissolution and bioavailability for a better delivery of anti-malarial drug.

  1. Distribution of multi-component solvents in solvent vapor extraction chamber

    Energy Technology Data Exchange (ETDEWEB)

    Das, S. [Society of Petroleum Engineers, Richardson, TX (United States)]|[Marathon Oil Corp., Houston, TX (United States)

    2008-10-15

    Vapex process performance is sensitive to operating pressures, temperatures and the types of solvent used. The hydrocarbon solvents used in Vapex processes typically have between 5 and 10 per cent hydrocarbon impurities, and the accumulation of dense phases inside the vapor chamber reduces gravity drainage potential. This study investigated the partitioning of solvent compounds inside the vapor chamber during in situ Vapex processes.The aim of the study was to examine how the different components of the mixed solvent partitioned inside the extracted chamber during the oil and vapor phase. A 2-D homogenous reservoir model was used to simulate the Vapex process with a solvent mixture comprised of propane and methane at various percentages. The effect of injecting a hot solvent vapor was also investigated. The study showed that injected methane accumulated at both the top and the extraction interface. Accumulations near the top had a positive impact on solvent confinement in thin reservoirs. Diffusion of the solvent component was controlled by gas phase molecular diffusion, and was much faster than the diffusion of solvent molecules in the liquid phase. The use of hot solvent mixtures slowed the extraction process due to lower solvent solubility in the oil phase. It was concluded that the negative impact on viscosity reduction by dilution was not compensated by rises in temperature. 6 refs., 11 figs.

  2. Green solvents and technologies for oil extraction from oilseeds

    OpenAIRE

    Kumar, S. P. Jeevan; Prasad, S. Rajendra; Banerjee, Rintu; Agarwal, Dinesh K.; Kulkarni, Kalyani S.; Ramesh, K. V.

    2017-01-01

    Oilseeds are crucial for the nutritional security of the global population. The conventional technology used for oil extraction from oilseeds is by solvent extraction. In solvent extraction, n-hexane is used as a solvent for its attributes such as simple recovery, non-polar nature, low latent heat of vaporization (330?kJ/kg) and high selectivity to solvents. However, usage of hexane as a solvent has lead to several repercussions such as air pollution, toxicity and harmfulness that prompted to...

  3. Photophysical properties of coumarin-120: Unusual behavior in nonpolar solvents

    International Nuclear Information System (INIS)

    Pal, Haridas; Nad, Sanjukta; Kumbhakar, Manoj

    2003-01-01

    Photophysical properties of coumarin-120 (C120; 7-amino-4-methyl-1,2-benzopyrone) dye have been investigated in different solvents using steady-state and time-resolved fluorescence and picosecond laser flash photolysis (LFP) and nanosecond pulse radiolysis (PR) techniques. C120 shows unusual photophysical properties in nonpolar solvents compared to those in other solvents of moderate to higher polarities. Where the Stokes shifts (Δν-bar=ν-bar abs -ν-bar fl ), fluorescence quantum yields (Φ f ), and fluorescence lifetimes (τ f ) show more or less linear correlation with the solvent polarity function Δf={(ε-1)/(2ε+1)-(n 2 -1)/(2n 2 +1)}, all these parameters are unusually lower in nonpolar solvents. Unlike in other solvents, both Φ f and τ f in nonpolar solvents are also strongly temperature dependent. It is indicated that the excited singlet (S 1 ) state of C120 undergoes a fast activation-controlled nonradiative deexcitation in nonpolar solvents, which is absent in all other solvents. LFP and PR studies indicate that the intersystem crossing process is negligible for the present dye in all the solvents studied. Photophysical behavior of C120 in nonpolar solvent has been rationalized assuming that in these solvents the dye exists in a nonpolar structure, with its 7-NH 2 group in a pyramidal configuration. In this structure, since the 7-NH 2 group is bonded to the 1,2-benzopyrone moiety by a single bond, the former group can undergo a fast flip-flop motion, which in effect causes the fast nonradiative deexcitation of the dye excited state. In moderate to higher polarity solvents, it is indicated that the dye exists in an intramolecular charge-transfer structure, where the bond between 7-NH 2 group and the 1,2-benzopyrone moiety attains substantial double bond character. In this structure, the flip-flop motion of the 7-NH 2 group is highly restricted and thus there is no fast nonradiative deexcitation process for the excited dye

  4. Solvent effects on the fluorescence and effective three-photon absorption of a Zn(II)-[meso-tetrakis(4-octyloxyphenyl)porphyrin

    Science.gov (United States)

    Wan, Yong; Xue, Yuxiong; Sheng, Ning; Rui, Guanghao; Lv, Changgui; He, Jun; Gu, Bing; Cui, Yiping

    2018-06-01

    The fluorescence and effective three-photon absorption (3PA) properties of Zn(II)-[meso-tetrakis(4-octyloxyphenyl)porphyrin] (labeled Zn(II)-porphyrin) dissolved in three different polar solvents were systematically investigated. The electrochemical and photophysical properties of Zn(II)-porphyrin were investigated by 1H NMR spectra, IR spectra, mass spectroscopy, and electronic absorption spectra. The fluorescence emission of Zn(II)-porphyrin in three different solvents excited at the wavelengths of 420 nm (Soret band) and 550 nm (Q-band) were analyzed. By performing Z-scan experiments with femtosecond laser pulses at a wavelength of 800 nm, the effective 3PA process of Zn(II)-porphyrin in three different solvents was observed and the underlying mechanism was discussed in detail. It is found that the fluorescence spectra slightly depend on the polarity of the solvent. Interestingly, the effective 3PA properties of Zn(II)-porphyrin strongly depend on the solvent polarity. The lower the solvent polarity is, the larger effective 3PA cross-section is. Low polar solvents are beneficial to applications of Zn(II)-porphyrin in optical limiting, photodynamic therapy, etc.

  5. Scattering of polarized electrons from polarized targets: Coincidence reactions and prescriptions for polarized half-off-shell single-nucleon cross sections

    International Nuclear Information System (INIS)

    Caballero, J.A.; Massachusetts Inst. of Tech., Cambridge, MA; Donnelly, T.W.; Massachusetts Inst. of Tech., Cambridge, MA; Poulis, G.I.; Massachusetts Inst. of Tech., Cambridge, MA

    1993-01-01

    Coincidence reactions of the type vector A( vector e, e'N)B involving the scattering of polarized electrons from polarized targets are discussed within the context of the plane-wave impulse approximation. Prescriptions are developed for polarized half-off single-nucleon cross sections; the different prescriptions are compared for typical quasi-free kinematics. Illustrative results are presented for coincidence polarized electron scattering from typical polarized nuclei. (orig.)

  6. Isolation Of Compounds Of Steroids Teripang Gamat (Stichopus variegatus With Various Types Of Solvents

    Directory of Open Access Journals (Sweden)

    Meydia Meydia

    2016-12-01

    Full Text Available Sea cucumber is one of the fisheries commodity that has an important economic value. Generally istraded in dried form (beche-de-mer. One of thebioactive substances contained in sea cucumber is steroidcompounds that serves as an aphrodisiac and sex reversal. The purpose of this study was to extract thesteroid of the gamma sea cucumber by using three types of solvents (methanol, ethyl acetate and hexaneand get the best solvent in producing the highest yield of the steroids. The study revealed that steroid ofgamma sea cucumber (Stichopus variegatus dissolved completely ethyl acetate (semi-polar solvent duringthe first phase, second phase and the third phase of extraction. In the methanol (polar solvent steroids onlydissolved in the first extraction phase, while using the hexane (non polar solvent steroid was undetectable.Fractionation by thin layer chromatography was obtained two fractions that identified as cholesterol (Rf =0.96 and testosterone (Rf = 0.91.

  7. Sugar-Based Polyamides: Self-Organization in Strong Polar Organic Solvents.

    Science.gov (United States)

    Rosu, Cornelia; Russo, Paul S; Daly, William H; Cueto, Rafael; Pople, John A; Laine, Roger A; Negulescu, Ioan I

    2015-09-14

    Periodic patterns resembling spirals were observed to form spontaneously upon unassisted cooling of d-glucaric acid- and d-galactaric acid-based polyamide solutions in N-methyl-N-morpholine oxide (NMMO) monohydrate. Similar observations were made in d-galactaric acid-based polyamide/ionic liquid (IL) solutions. The morphologies were investigated by optical, polarized light and confocal microscopy assays to reveal pattern details. Differential scanning calorimetry was used to monitor solution thermal behavior. Small- and wide-angle X-ray scattering data reflected the complex and heterogeneous nature of the self-organized patterns. Factors such as concentration and temperature were found to influence spiral dimensions and geometry. The distance between rings followed a first-order exponential decay as a function of polymer concentration. Fourier-Transform Infrared Microspectroscopy analysis of spirals pointed to H-bonding between the solvent and the pendant hydroxyl groups of the glucose units from the polymer backbone. Tests on self-organization into spirals of ketal-protected d-galactaric acid polyamides in NMMO monohydrate confirmed the importance of the monosaccharide's pendant free hydroxyl groups on the formation of these patterns. Rheology performed on d-galactaric-based polyamides at high concentration in NMMO monohydrate solution revealed the optimum conditions necessary to process these materials as fibers by spinning. The self-organization of these sugar-based polyamides mimics certain biological materials.

  8. Influence of the solvent environments on the spectral features of CdSe quantum dots with and without ZnS shell

    Energy Technology Data Exchange (ETDEWEB)

    Ibnaouf, K.H., E-mail: kheo90@gmail.com [Al Imam Mohammad Ibn Saud Islamic University (IMSIU), Physics Department, College of Science, P.O. Box 90905, Riyadh 11623 (Saudi Arabia); Prasad, Saradh; Al Salhi, M.S.; Hamdan, A. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Research Chair for Laser Diagnosis of Cancer, King Saud University (Saudi Arabia); Zaman, M.B. [CEREM, College of Engineering, King Saud University (Saudi Arabia); Advanced Medical Research Institute of Canada, Sudbury (Canada); El Mir, L. [Al Imam Mohammad Ibn Saud Islamic University (IMSIU), Physics Department, College of Science, P.O. Box 90905, Riyadh 11623 (Saudi Arabia)

    2014-05-01

    The spectral properties of 5 nm size of bare CdSe and (CdSe)ZnS core–shell quantum dots (QDs) have been recorded and investigated under different solvent environments with different polarities and different concentrations. The results showed that the spectral profile of absorption did not change for both quantum dots in different solvents under a wide range of concentrations. On the other hand, the photoluminescence (PL) spectra of (CdSe)ZnS core–shell quantum dots in non-polar solvents showed two bands; the primary around 420 nm and the secondary around 620 nm. In contrast, the PL spectra of bare CdSe in non-polar solvents, showed a very strong band around 590 nm, with a total absence of the primary wavelength band at 420 nm. Under high polar solvent environments, bare CdSe showed a new peak around 420 nm, which was totally absent in non-polar solvent. Therefore, the solvent plays an important role in the PL spectra of bare CdSe and (CdSe)ZnS core–shell quantum dots.

  9. Sensitivity of viscosity Arrhenius parameters to polarity of liquids

    Science.gov (United States)

    Kacem, R. B. H.; Alzamel, N. O.; Ouerfelli, N.

    2017-09-01

    Several empirical and semi-empirical equations have been proposed in the literature to estimate the liquid viscosity upon temperature. In this context, this paper aims to study the effect of polarity of liquids on the modeling of the viscosity-temperature dependence, considering particularly the Arrhenius type equations. To achieve this purpose, the solvents are classified into three groups: nonpolar, borderline polar and polar solvents. Based on adequate statistical tests, we found that there is strong evidence that the polarity of solvents affects significantly the distribution of the Arrhenius-type equation parameters and consequently the modeling of the viscosity-temperature dependence. Thus, specific estimated values of parameters for each group of liquids are proposed in this paper. In addition, the comparison of the accuracy of approximation with and without classification of liquids, using the Wilcoxon signed-rank test, shows a significant discrepancy of the borderline polar solvents. For that, we suggested in this paper new specific coefficient values of the simplified Arrhenius-type equation for better estimation accuracy. This result is important given that the accuracy in the estimation of the viscosity-temperature dependence may affect considerably the design and the optimization of several industrial processes.

  10. Isolation Of Compounds Of Steroids Teripang Gamat (Stichopus variegatus With Various Types Of Solvents

    Directory of Open Access Journals (Sweden)

    Meydia Meydia

    2017-02-01

    Full Text Available AbstractSea cucumber is one of the fisheries commodity that has an important economic value. Generally is traded in dried form (beche-de-mer. One of thebioactive substances contained in sea cucumber is steroid compounds that serves as an aphrodisiac and sex reversal. The purpose of this study was to extract the steroid of the gamma sea cucumber by using three types of solvents (methanol, ethyl acetate and hexane and get the best solvent in producing the highest yield of the steroids. The study revealed that steroid of gamma sea cucumber (Stichopus variegatus dissolved completely ethyl acetate (semi-polar solvent during the first phase, second phase and the third phase of extraction. In the methanol (polar solvent steroids only dissolved in the first extraction phase, while using the hexane (non polar solvent steroid was undetectable. Fractionation by thin layer chromatography was obtained two fractions that identified as cholesterol (Rf = 0.96 and testosterone (Rf = 0.91.

  11. Sorption mechanism of solvent vapors to coals; Sekitan eno yobai joki no shuchaku kiko no kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, K.; Takanohashi, T.; Iino, M. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science

    1996-10-28

    With an objective to clarify the interactions between micropore structure of coal and solvent reagents, a sorption experiment was carried out under solvent saturated vapor pressure. Low-volatile bituminous coal, Pocahontas No. 3 coal, has the aromatic ring structure developed, and makes solvent more difficult to diffuse into coal, hence sorption amount is small. Methanol has permeated since its polarity is high. High-volatile bituminous coal, Illinois No. 6 coal, makes solvent penetrate easily, and the sorption amount was large with both of aromatic and polar solvents. Since brown coal, Beulah Zap coal, contains a large amount of oxygen, and hydrogen bonding is predominant, sorption amount of cyclohexane and benzene having no polarity is small. Methanol diffuses while releasing hydrogen bond due to its polarity, and its sorption amount is large. A double sorption model is available, which expresses the whole sorption amount as a sum of physical sorption amount and amount of permeation into coal. This model was applied when it explained successfully the sorption behavior of the solvents relative to coals, excepting some of the systems. However, also observed were such abnormal behavior as sorption impediment due to interactions between coal surface and solvents, and permeation impediment due to hydroxyl groups inside the coals. 1 ref., 10 figs., 2 tabs.

  12. Solvent effects on the photochemistry of dimethyl sulfoxide-Cl complexes studied by combined pulse radiolysis and laser flash photolysis

    International Nuclear Information System (INIS)

    Sumiyoshi, Takashi; Minegishi, Hideki; Fujiyoshi, Ryoko; Sawamura, Sadashi

    2006-01-01

    Photolysis of complexes of dimethyl sulfoxide (DMSO) with chlorine atoms results in rapid and permanent photobleaching which may be due to intramolecular hydrogen abstraction. The effects of solvent polarity were examined in a wide variety of DMSO-carbon tetrachloride mixed solvents. The quantum yields of photobleaching decreased from 0.27 to 0.08 as the solvent polarity increased, while significant changes were observed in the low DMSO concentration range ( -3 ). This cannot be accounted for by simple solvent polarity effects. The effects of polar and nonpolar additives were also examined and it is concluded that the specific solvation effect of DMSO was the main cause of the significant change in quantum yields in the low concentration range of DMSO

  13. Application of acetone acetals as water scavengers and derivatization agents prior to the gas chromatographic analysis of polar residual solvents in aqueous samples.

    Science.gov (United States)

    van Boxtel, Niels; Wolfs, Kris; Van Schepdael, Ann; Adams, Erwin

    2015-12-18

    The sensitivity of gas chromatography (GC) combined with the full evaporation technique (FET) for the analysis of aqueous samples is limited due to the maximum tolerable sample volume in a headspace vial. Using an acetone acetal as water scavenger prior to FET-GC analysis proved to be a useful and versatile tool for the analysis of high boiling analytes in aqueous samples. 2,2-Dimethoxypropane (DMP) was used in this case resulting in methanol and acetone as reaction products with water. These solvents are relatively volatile and were easily removed by evaporation enabling sample enrichment leading to 10-fold improvement in sensitivity compared to the standard 10μL FET sample volumes for a selection of typical high boiling polar residual solvents in water. This could be improved even further if more sample is used. The method was applied for the determination of residual NMP in an aqueous solution of a cefotaxime analogue and proved to be considerably better than conventional static headspace (sHS) and the standard FET approach. The methodology was also applied to determine trace amounts of ethylene glycol (EG) in aqueous samples like contact lens fluids, where scavenging of the water would avoid laborious extraction prior to derivatization. During this experiment it was revealed that DMP reacts quantitatively with EG to form 2,2-dimethyl-1,3-dioxolane (2,2-DD) under the proposed reaction conditions. The relatively high volatility (bp 93°C) of 2,2-DD makes it possible to perform analysis of EG using the sHS methodology making additional derivatization reactions superfluous. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Extraction of Polychlorinated Biphenyls (PCBs) and Dibenzyl Disulfide from Transformer Oils using Polar Aprotic Solvents andReductive Dehalogenation of Extracted PCBs

    OpenAIRE

    Kaštánek, P. (Petr); Kaštánek, F. (František); Maléterová, Y. (Ywetta); Matějková, M. (Martina); Spáčilová, L. (Lucie); Šolcová, O. (Olga)

    2014-01-01

    Extractions of PCBs from mineral oils with polar aprotic solvents (PAS) acrylonitrile AC, dimethyl sulfoxide DMSO, dimethyl formamide DMF, N-methyl pyrrolidone NMP and propylene carbonate PC were performed in order to compare the extraction efficiencies. In a single-stage extraction performed at room temperature, the efficiencies ranged from the highest to the lowest as follows: NMP → DMF → DMSO → PC → AC. NMP exhibited the highest efficiency, around 70%. . Pyridine N-oxide was also used a...

  15. Generating highly polarized nuclear spins in solution using dynamic nuclear polarization

    DEFF Research Database (Denmark)

    Wolber, J.; Ellner, F.; Fridlund, B.

    2004-01-01

    A method to generate strongly polarized nuclear spins in solution has been developed, using Dynamic Nuclear Polarization (DNP) at a temperature of 1.2K, and at a field of 3.354T, corresponding to an electron spin resonance frequency of 94GHz. Trityl radicals are used to directly polarize 13C...... and other low-γ nuclei. Subsequent to the DNP process, the solid sample is dissolved rapidly with a warm solvent to create a solution of molecules with highly polarized nuclear spins. Two main applications are proposed: high-resolution liquid state NMR with enhanced sensitivity, and the use...

  16. Radiation destruction of vitamin A in lipid solvents

    International Nuclear Information System (INIS)

    Snauwaert, F.; Maes, E.; Tobback, P.; Bhushan, B.

    1978-01-01

    The radiation response of vitamin A alcohol and its acetate derivative was compared in different lipid solvents. In all the solvents vitamin A alcohol exhibited a much higher radiation sensitivity than its ester counterpart. The nature of the solvent and the initial concentration was found to have a great influence on the extent of radiation degradation of vitamin A alcohol. In contrast to a high radiolability in non-polar solvents, vitamin A alcohol exhibited a remarkable stability in isopropanol. In addition, in isopropanol the G(-) relationship with radiation dose showed a reverse trend to that observed for other solvents. A thin-layer chromatographic procedure was developed for separation of the radiation degradation products. (author)

  17. Structure determination of small molecular phase in coal by solvent extraction

    Energy Technology Data Exchange (ETDEWEB)

    Feng, J.; Wang, B.; Ye, C.; Li, W.; Xie, K. [Taiyuan University of Technology, Taiyuan (China)

    2004-04-01

    7 typical Chinese coal samples were extracted by NMP/CS{sub 2} system at around 90{degree}C by Soxhlet method. Compared with results from NMP, a higher coal extraction rate was acquired when NMP + CS{sub 2} solvent system was adopted. Except for anthracite extraction rate of about 20% was acquired, particularly 41% for long flame coal. By using the method of retention index of coal extracts analysis by HPLC, it is found that the polar part with less than six-carbon numbers in coal is the active site for coal reactivity, and the inert site belongs to the aromatic hydrocarbon derivation with 3 aromatic rings. 13 refs., 3 figs., 2 tabs.

  18. Selective nonspecific solvation under dielectric saturation and fluorescence spectra of dye solutions in binary solvents.

    Science.gov (United States)

    Bakhshiev, N G; Kiselev, M B

    1991-09-01

    The influence of selective nonspecific solvation on the fluorescence spectra of three substitutedN-methylphthalimides in a binary solvent system consisting of a nonpolar (n-heptane) and a polar (pyridine) component has been studied under conditions close to dielectric saturation. The substantially nonlinearity of the effect is confirmation that the spectral shifts of fluorescence bands depend on the number of polar solvent molecules involved in solvating the dye molecule. The measured fluorescence spectral shifts determined by substituting one nonpolar solvent molecula with a polar one in the proximity of the dye molecule agree quantitatively with the forecasts of the previously proposed semiempirical theory which describes this nonlinear solvation phenomenon.

  19. Solvent effects on the excited-state double proton transfer mechanism in the 7-azaindole dimer: a TDDFT study with the polarizable continuum model.

    Science.gov (United States)

    Yu, Xue-Fang; Yamazaki, Shohei; Taketsugu, Tetsuya

    2017-08-30

    Solvent effects on the excited-state double proton transfer (ESDPT) mechanism in the 7-azaindole (7AI) dimer were investigated using the time-dependent density functional theory (TDDFT) method. Excited-state potential energy profiles along the reaction paths in a locally excited (LE) state and a charge transfer (CT) state were calculated using the polarizable continuum model (PCM) to include the solvent effect. A series of non-polar and polar solvents with different dielectric constants were used to examine the polarity effect on the ESDPT mechanism. The present results suggest that in a non-polar solvent and a polar solvent with a small dielectric constant, ESDPT follows a concerted mechanism, similar to the case in the gas phase. In a polar solvent with a relatively large dielectric constant, however, ESDPT is likely to follow a stepwise mechanism via a stable zwitterionic intermediate in the LE state on the adiabatic potential energy surface, although inclusion of zero-point vibrational energy (ZPE) corrections again suggests the concerted mechanism. In the meantime, the stepwise reaction path involving the CT state with neutral intermediates is also examined, and is found to be less competitive than the concerted or stepwise path in the LE state in both non-polar and polar solvents. The present study provides a new insight into the experimental controversy of the ESDPT mechanism of the 7AI dimer in a solution.

  20. Thermodynamic constrains for life based on non-aqueous polar solvents on free-floating planets.

    Science.gov (United States)

    Badescu, Viorel

    2011-02-01

    Free-floating planets (FFPs) might originate either around a star or in solitary fashion. These bodies can retain molecular gases atmospheres which, upon cooling, have basal pressures of tens of bars or more. Pressure-induced opacity of these gases prevents such a body from eliminating its internal radioactive heat and its surface temperature can exceed for a long term the melting temperature of a life-supporting solvent. In this paper two non-aqueous but still polar solvents are considered: hydrogen sulfide and ammonia. Thermodynamic requirements to be fulfilled by a hypothetic gas constituent of a life-supporting FFP's atmosphere are studied. The three gases analyzed here (nitrogen, methane and ethane) are candidates. We show that bodies with ammonia oceans are possible in interstellar space. This may happen on FFPs of (significantly) smaller or larger mass than the Earth. Generally, in case of FFP smaller in size than the Earth, the atmosphere exhibits a convective layer near the surface and a radiative layer at higher altitudes while the atmosphere of FFPs larger in size than Earth does not exhibit a convective layer. The atmosphere mass of a life-hosting FFP of Earth size is two or three orders of magnitude larger than the mass of Earth atmosphere. For FFPs larger than the Earth and specific values of surface pressure and temperature, there are conditions for condensation (in the ethane atmosphere). Some arguments induce the conclusion than the associated surface pressures and temperatures should be treated with caution as appropriate life conditions.

  1. Nitropyrroles, Diels-Alder reactions assisted by microwave irradiation and solvent effect. An experimental and theoretical study

    Science.gov (United States)

    Mancini, Pedro M. E.; Kneeteman, María N.; Cainelli, Mauro; Ormachea, Carla M.; Domingo, Luis R.

    2017-11-01

    The behaviors of N-tosylnitropyrroles acting as electrophilic dienophiles in polar Diels-Alder reactions joint to different dienes of increeased nucleophilicity are analyzed. The reactions were developed under microwave irradiation using toluene or protic ionic liquids (PILs) as solvents and in free solvent conditions. In all the cases explored we observed good yields in short reaction times. For these reactions, the free solvent condition and the use of protic ionic liquids as solvents offer similar results. However, the free solvent conditions favor environmental sustainability. The role of PILs in these polar Diels-Alder reactions has been theoretically studied within the Molecular Electron Density Theory.

  2. Sorption behaviour of polystyrene grafted sago starch in various solvents

    International Nuclear Information System (INIS)

    Janarthanan, P.; Yunus, W.M.Z.W.; Ahmed, M.B.; Rahman, M.Z.; Haron, M.J.; Silong, S.

    2001-01-01

    This paper describes swelling properties of polystyrene grafted sago starch in dimethyl sulfoxide (DMSO); chloroform (CHCl/sub 3/), water, acetone carbon tetrachloride (CCl/sub 4/) cyclohexanone and toluene. The copolymer for this study was prepared by grafting styrene onto sago starch using ceric ammonium nitrate as a redox initiator. Solvent uptake of the copolymer with respect to time was obtained by soaking the samples in chosen solvents for various time intervals at 25+-1 degree centigrade. The results obtained from swelling of polystyrene grafted sago starch in polar and non polar solvents showed that the percentage of swelling at equilibrium and the swelling rate coefficient decreased in the following order: DMSO > water > acetone cyclohexanone approx. CHCl/sub 3/ > toluene approx. CCl/sub 4/. Dimethyl sulfoxide showed the highest percentage of swelling at equilibrium that is 765%. Diffusions of the solvents onto the polymers were found to be of a Fickian only for DMSO. (author)

  3. Solvent density mode instability in non-polar solutions

    Indian Academy of Sciences (India)

    and excited states of the solute with the compressibility and solvent structure is found to have .... The organization of the rest of the paper is as follows. ...... For the ground state term, as C2 is nearly flat at qσ = q0 = 2π, we can safely ignore.

  4. Communication: Potentials of mean force study of ionic liquid ion pair aggregation in polar covalent molecule solvents

    Science.gov (United States)

    Bandlamudi, Santosh Rathan Paul; Benjamin, Kenneth M.

    2018-05-01

    Molecular dynamics (MD) simulations were conducted for 1-ethyl-3-methylimidazolium methylsulfate [EMIM][MeSO4] dissolved in six polar covalent molecules [acetic acid, acetone, chloroform, dimethyl sulfoxide (DMSO), isopropyl alcohol, and methanol] to understand the free energies of ionic liquid (IL) ion pairing/aggregation in the limit of infinite dilution. Free energy landscapes or potentials of mean force (PMF) were computed using umbrella sampling and the weighted histogram analysis method. The PMF studies showed the strongest IL ion pairing in chloroform, and the strength of IL ion pairing decreases in the order of chloroform, acetone, propanol, acetic acid, DMSO, and methanol. In the limit of infinite dilution, the free energy curves for IL ion aggregation in co-solvents were characterized by two distinct minima [global (˜3.6 Å) and local (˜5.7 Å)], while free energy values at these minima differed significantly for IL in each co-solvent. The PMF studies were extended for determining the free energy of IL ion aggregation as a function of concentration of methanol. Studies showed that as the concentration of methanol increased, the free energy of ion aggregation decreased, suggesting greater ion pair stability, in agreement with previously reported MD clustering and radial distribution function data.

  5. Spectral behaviour of eosin Y in different solvents and aqueous surfactant media

    Science.gov (United States)

    Chakraborty, Moumita; Panda, Amiya Kumar

    2011-10-01

    Photophysical behaviour of the anionic xanthene dye, eosin Y (EY) was investigated in solvents of different polarities as well as in the presence of aqueous cationic surfactants. From the correlation between ET(30) and Kosower Z values of EY in different solvents, subsequent parameters for EY were determined in the presence of surfactants. A red shift, both in the absorption and emission spectra of EY, was observed with decreasing solvent polarity. Dimerisation of EY was found to be dependent on solvent polarity. Cationic surfactants retarded the process of dimerisation, which were evident from the lower dimerisation constant ( KD) values, compared to that of in pure water. Dye-surfactant interaction constants were determined at different temperatures (298-318 K) and subsequently the thermodynamic parameters, viz., Δ G°, Δ H° and Δ S° were evaluated using the interaction constant values. The fluorescence spectra of EY followed the same trend as in the absorption spectra, although with lesser extents. Stokes shifts were calculated and correlated with the polarity of the medium. Fluorescence of EY was initially quenched by the cationic surfactants in their pre-micellar region, which then followed a red shift with intensity enhancement. Fluorescence quenching was found to be of Stern-Volmer type where the excited state lifetime of EY remained unchanged in different surfactant media. However, the anisotropy value of EY was changed in the post micellar region of surfactants.

  6. Heavy atoms as molecular probes in studying the solvent dependence of the dynamics of triplet exciplexes

    International Nuclear Information System (INIS)

    Steiner, U.; Winter, G.

    1981-01-01

    Electron transfer reactions between thiopyronine triplet (acceptor 3 A + ) and the electron donors (D), aniline, p-Br-aniline and p-I-aniline, are investigated by flash spectroscopy in solvents of different viscosity and polarity. Due to the heavy-atom effect the radical yield becomes very sensitive to the solvent influence, which can be explained by the dynamic properties of a triplet exciplex ( 3 (AD + )) formed as a primary product in the reaction between acceptor triplet and donor. Whereas on variation of solvent viscosity the solvent cage effect on the dissociation of 3 (AD + ) is observed, a change in solvent polarity is suggested to affect the radiationless deactivation of 3 (AD + ) to the ground state of the components. (author)

  7. Supercapacitor Electrolyte Solvents with Liquid Range Below -80 C

    Science.gov (United States)

    Brandon, Erik; Smart, Marshall; West, William

    2010-01-01

    A previous NASA Tech Brief ["Low-Temperature Supercapacitors" (NPO-44386) NASA Tech Briefs, Vol. 32, No 7 (July 2008), page 32] detailed ongoing efforts to develop non-aqueous supercapacitor electrolytes capable of supporting operation at temperatures below commercially available cells (which are typically limited to charging and discharging at > or equal to -40 C). These electrolyte systems may enable energy storage and power delivery for systems operating in extreme environments, such as those encountered in the Polar regions on Earth or in the exploration of space. Supercapacitors using these electrolytes may also offer improved power delivery performance at moderately low temperatures (e.g. -40 to 0 C) relative to currently available cells, offering improved cold-cranking and cold-weather acceleration capabilities for electrical or hybrid vehicles. Supercapacitors store charge at the electrochemical double-layer, formed at the interface between a high surface area electrode material and a liquid electrolyte. The current approach to extending the low-temperature limit of the electrolyte focuses on using binary solvent systems comprising a high-dielectric-constant component (such as acetonitrile) in conjunction with a low-melting-point co-solvent (such as organic formates, esters, and ethers) to depress the freezing point of the system, while maintaining sufficient solubility of the salt. Recent efforts in this area have led to the identification of an electrolyte solvent formulation with a freezing point of -85.7 C, which is achieved by using a 1:1 by volume ratio of acetonitrile to 1,3-dioxolane

  8. An organic solvent-, detergent-, and thermo-stable alkaline protease from the mesophilic, organic solvent-tolerant Bacillus licheniformis 3C5.

    Science.gov (United States)

    Rachadech, W; Navacharoen, A; Ruangsit, W; Pongtharangkul, T; Vangnai, A S

    2010-01-01

    Bacillus licheniformis 3C5, isolated as mesophilic bacterium, exhibited tolerance towards a wide range of non-polar and polar organic solvents at 45 degrees C. It produced an extracellular organic solvent-stable protease with an apparent molecular mass of approximately 32 kDa. The inhibitory effect of PMSF and EDTA suggested it is likely to be an alkaline serine protease. The protease was active over abroad range of temperatures (45-70 degrees C) and pH (8-10) range with an optimum activity at pH 10 and 65 degrees C. It was comparatively stable in the presence ofa relatively high concentration (35% (v/v)) of organic solvents and various types of detergents even at a relatively high temperature (45 degrees C). The protease production by B. licheniformis 3C5 was growth-dependent. The optimization of carbon and nitrogen sources for cell growth and protease production revealed that yeast extract was an important medium component to support both cell growth and the protease production. The overall properties of the protease produced by B. licheniformis 3C5 suggested that this thermo-stable, solvent-stable, detergent-stable alkaline protease is a promising potential biocatalyst for industrial and environmental applications.

  9. In Vitro Toxicological Evaluation of Cigarette Smoke Particulate Matter: Effect of Dimethyl Sulfoxide (DMSO as Solvent

    Directory of Open Access Journals (Sweden)

    Misra M

    2014-12-01

    Full Text Available This study examined the potential to minimize the cytotoxic or genotoxic effects that dimethylsulfoxide (DMSO, when used as solvent, has on the in vitro interleukin-8 (IL-8 release, mammalian cell cytotoxicity and micronuclei formation, and bacterial mutagenesis induced by cigarette smoke wet total particulate matter (WTPM. The use of DMSO as a solvent vehicle for test articles of limited water solubility is widely applied in in vitro assays due to its moderate toxicity to test organisms and its excellent solvent properties for both polar and non-polar compounds, such as WTPM. A significant DMSO dose-dependent depletion in the IL-8 release was observed, with or without the addition of WTPM, at concentrations spanning those typically employed in in vitro assays. DMSO at 3.6% reduced cell viability 40-50%. Overall, DMSO at final concentrations of 0.5% and 4.0% resulted in about 50% and 90% depletion of final IL-8 levels, respectively. DMSO-induced cytotoxicity was evident only at concentrations of 1.5% or more, a concentration higher than that typically employed in such testing. The WTPM-induced cytotoxicity was equivalent at low ranges of DMSO concentrations. DMSO concentrations of 3.6% or higher resulted in an increase of cytotoxicity by 20-25%. DMSO alone did not give rise to bacterial mutagenicity at doses from 0% to 3.9%; however, WTPM exposure with increasing levels of DMSO resulted in increased toxicity of the WTPM at doses of DMSO greater than 6.9%, as indicated by lower revertant counts. This effect suggests that for Ames assay analysis of WTPM collected in DMSO, the level of DMSO should be minimized to prevent lower revertant counts due to DMSO-induced toxicity. DMSO alone gave a dose-dependent increase in the background micronuclei percentage, with a statistically significant increase at 4%. In the presence of WTPM, DMSO at 3% concentration resulted in a significantly higher micro-nucleus frequency, suggesting a possible clastogenic

  10. Solvent Vapour Detection with Cholesteric Liquid Crystals—Optical and Mass-Sensitive Evaluation of the Sensor Mechanism

    Directory of Open Access Journals (Sweden)

    Adnan Mujahid

    2010-05-01

    Full Text Available Cholesteric liquid crystals (CLCs are used as sensitive coatings for the detection of organic solvent vapours for both polar and non-polar substances. The incorporation of different analyte vapours in the CLC layers disturbs the pitch length which changes the optical properties, i.e., shifting the absorption band. The engulfing of CLCs around non-polar solvent vapours such as tetrahedrofuran (THF, chloroform and tetrachloroethylene is favoured in comparison to polar ones, i.e., methanol and ethanol. Increasing solvent vapour concentrations shift the absorbance maximumto smaller wavelengths, e.g., as observed for THF. Additionally, CLCs have been coated on acoustic devices such as the quartz crystal microbalance (QCM to measure the frequency shift of analyte samples at similar concentration levels. The mass effect for tetrachloroethylene was about six times higher than chloroform. Thus, optical response can be correlated with intercalation in accordance to mass detection. The mechanical stability was gained by combining CLCs with imprinted polymers. Therefore, pre-concentration of solvent vapours was performed leading to an additional selectivity.

  11. Excited-state inter- and intramolecular proton transfer in methyl 3-hydroxy-2-quinoxalinate: effects of solvent and acid or base concentrations

    International Nuclear Information System (INIS)

    Dogra, S.K.

    2005-01-01

    Absorption, fluorescence excitation and fluorescence spectroscopy, combined with time-dependent spectroscopy and semi-empirical (AM1) and density functional theory using Gaussian 98 program calculations have been used to study the effects of solvent and acid or base concentration on the spectral characteristics of methyl 3-hydroxy-2-quinoxalinate (M3HQ). M3HQ is present as enol in less polar solvents and as keto in polar media. In non-polar solvents, large Stokes shifted fluorescence band is assigned to the phototautomer, formed by the excited-state intramolecular proton transfer, whereas fluorescence is only observed from keto in the polar solvents. In aqueous and polar solvents the monocation (MC5/MC6) is formed by protonating the carbonyl oxygen atom in the ground (S 0 ) and the first excited singlet states (S 1 ). Dication is formed by protonating one of ?N- atom of MC5/MC6. Monoanion is formed by deprotonating the phenolic proton of enol in the basic solution. pK a values for different prototropic equilibriums were determined in S 0 and S 1 states and discussed

  12. Effects of Extraction Solvents on the Quantification of Free Amino Acids in Lyophilised Brewer’s Yeast

    Directory of Open Access Journals (Sweden)

    Andreea STĂNILĂ

    2018-05-01

    Full Text Available The aim of this work was to test some solvents in order to improve the free amino acids extraction from lyophilised brewer’s yeast. The brewer’ yeast was treated with four types of extraction solvents: Solvent I – acetonitrile 25%/HCl 0.01M (ACN; Solvent II – ethanol 80%; solvent III – HCl 0.05M/deionized water (1/1 volume; Solvent IV – HCl 0.05M/ethanol 80% (1/1 volume. The supernatants were analysed by HPLC-DAD-ESI-MS method. Acetonitrile provided the less quantities and number of amino acids extracted due to its weaker polarity. Solvent II and IV (ethanol, respectively acidified ethanol, which have an increased polarity, extracted 15 amino acids due to the addition of HCl in solvent IV. Solvent III (acidified water proved to be the best extraction solvent for the amino acids from brewer’s yeast providing the separation of 17 compounds: GLN, ASN, SER, GLY, ALA, ORN, PRO, HIS, LYS, GLU, TRP, LEU, PHE, ILE, AAA, HPHE, TYR.

  13. Diluent effects in solvent extraction. The Effects of Diluents in Solvent Extraction - a literature study

    International Nuclear Information System (INIS)

    Loefstroem-Engdahl, Elin; Aneheim, Emma; Ekberg, Christian; Foreman, Mark; Skarnemark, Gunnar

    2010-01-01

    The fact that the choice of organic diluent is important for a solvent extraction process goes without saying. Several factors, such as e.g. price, flash point, viscosity, polarity etc. each have their place in the planning of a solvent extraction system. This high number of variables makes the lack of compilations concerning diluent effects to an interesting topic. Often the interest for the research concerning a specific extraction system focuses on the extractant used and the complexes built up during an extraction. The diluents used are often classical ones, even if it has been shown that choice of diluent can affect extraction as well as separation in an extraction system. An attempt to point out important steps in the understanding of diluent effects in solvent extraction is here presented. This large field is, of course, not summarized in this article, but an attempt is made to present important steps in the understanding of diluents effects in solvent extraction. Trying to make the information concerning diluent effects and applications more easily accessible this review offers a selected summarizing of literature concerning diluents effects in solvent extraction. (authors)

  14. Nonhazardous solvent composition and method for cleaning metal surfaces

    International Nuclear Information System (INIS)

    Googin, J.M.; Simandl, R.F.; Thompson, L.M.

    1993-01-01

    A solvent composition for displacing greasy and oily contaminants as well as water and/or aqueous residue from metallic surfaces, especially surfaces of radioactive materials so that such surfaces can be wiped clean of the displaced contaminants, water and/or aqueous residue. The solvent composition consists essentially of a blend of nonpolar aliphatic hydrocarbon solvent having a minimum flash point of about 140 F and 2 to 25 volume percent of a polar solvent having a flash point sufficiently high so as to provide the solvent composition with a minimum flash point of at least 140 F. The solvent composition is nonhazardous so that when it is used to clean the surfaces of radioactive materials the waste in the form of paper or cloth wipes, lab coats and the like used in the cleaning operation is not considered to be mixed waste composed of a hazardous solvent and a radioactive material

  15. Dynamically polarized hydrogen target as a broadband, wavelength-independent thermal neutron spin polarizer

    International Nuclear Information System (INIS)

    Zhao Jinkui; Garamus, Vasil M.; Mueller, Wilhelm; Willumeit, Regine

    2005-01-01

    A hydrogen-rich sample with dynamically polarized hydrogen nuclei was tested as a wavelength-independent neutron transmission spin polarizer. The experiment used a modified setup of the dynamic nuclear polarization target station at the GKSS research center. The standard solvent sample at the GKSS DNP station was used. It is 2.8mm thick and consists of 43.4wt% water, 54.6wt% glycerol, and 2wt% of EHBA-Cr(v) complex. The wavelength of the incident neutrons for the transmission experiment was λ=8.1A with Δλ/λ=10%. The polarization of neutron beam after the target sample was analyzed with a supermirror analyzer. A neutron polarization of -52% was achieved at the hydrogen polarization of -69%. Further experiments will test the feasibility of other hydrogen-rich materials, such as methane, as the polarizer. A theoretical calculation shows that a polarized methane target would allow over 95% neutron polarizations with more than 30% transmission

  16. Optimization of soy isoflavone extraction with different solvents using the simplex-centroid mixture design.

    Science.gov (United States)

    Yoshiara, Luciane Yuri; Madeira, Tiago Bervelieri; Delaroza, Fernanda; da Silva, Josemeyre Bonifácio; Ida, Elza Iouko

    2012-12-01

    The objective of this study was to optimize the extraction of different isoflavone forms (glycosidic, malonyl-glycosidic, aglycone and total) from defatted cotyledon soy flour using the simplex-centroid experimental design with four solvents of varying polarity (water, acetone, ethanol and acetonitrile). The obtained extracts were then analysed by high-performance liquid chromatography. The profile of the different soy isoflavones forms varied with different extractions solvents. Varying the solvent or mixture used, the extraction of different isoflavones was optimized using the centroid-simplex mixture design. The special cubic model best fitted to the four solvents and its combination for soy isoflavones extraction. For glycosidic isoflavones extraction, the polar ternary mixture (water, acetone and acetonitrile) achieved the best extraction; malonyl-glycosidic forms were better extracted with mixtures of water, acetone and ethanol. Aglycone isoflavones, water and acetone mixture were best extracted and total isoflavones, the best solvents were ternary mixture of water, acetone and ethanol.

  17. Environment effects on the optical properties of some fluorinated poly(oxadiazole ether)s in binary solvent mixtures

    International Nuclear Information System (INIS)

    Homocianu, Mihaela; Ipate, Alina Mirela; Hamciuc, Corneliu; Airinei, Anton

    2015-01-01

    The solvatochromic behavior of some fluorinated poly(oxadiazole ether)s was studied using UV–vis absorption and fluorescence spectroscopy in neat solvents and in their solvent mixtures at several ratios of cosolvents. Quantitative investigations of the spectral changes caused by solvent polarity were discussed using the Lippert‐Mataga, Bakhshiev and Kawski–Chamma–Viallet polarity functions. Repartitioning of cosolvent between local (solvation shell) and bulk phase was investigated by means of a solvatochromic shift method in chloroform–N,N-dimethylformamide (CHCl 3 /DMF) and chloroform–dimethyl sulfoxide (CHCl 3 /DMSO) solvent mixtures. Solvatochromic properties in the binary solvent environments were predominantly influenced by the acidity and basicity of the solvent systems. The fluorescence quenching process by nitrobenzene was characterized by Stern–Volmer plots which display a positive deviation from linearity. This was explained by static and dynamic quenching mechanisms. - Highlights: • Solvatochromic behavior in solvent mixtures was studied. • Stokes shift and local environments in binary mixed solvent were discussed. • Repartitioning of cosolvent between local and bulk phase in solvent mixture has been investigated. • Fluorescence intensity was quenched in presence of nitrobenzene

  18. Solvents interactions with thermochromic print

    Directory of Open Access Journals (Sweden)

    Mirela Rožić

    2017-12-01

    Full Text Available In this study, the interactions between different solvents (benzene, acetone, cyclohexanone, various alcohols and water and thermochromic printing ink were investigated. Thermochromic printing ink was printed on metal surface. Components of thermochromic printing inks are polymeric microcapsules and classic yellow offset printing ink. Below its activation temperature, dye and developer within the microcapsules form a blue coloured complex. Therefore, thermochromic print is green. By heating above the activation temperature, blue colour of the complex turns into the leuco dye colourless state and the green colour of the prints turns into the yellow colour of the classic offset pigment. The results of the interaction with various solvents show that the thermochromic print is stable in all tested solvents except in ethanol, acetone and cyclohexanone. In ethanol, the green colour of the print becomes yellow. SEM analysis shows that microcapsules are dissolved. In acetone and cyclohexanone, the green colour of the print turns into blue, and the microcapsules become significantly more visible. Thus, the yellow pigment interacts with examined ketones. Based on the obtained interactions it can be concluded that the microcapsules have more polar nature than the classical pigment particles. Solvent-thermocromic print interactions were analysed using Hansen solubility parameters that rank the solvents based on their estimated interaction capabilities.

  19. Self-Assembly of Block and Graft Copolymers in Organic Solvents: An Overview of Recent Advances

    Directory of Open Access Journals (Sweden)

    Leonard Ionut Atanase

    2018-01-01

    Full Text Available This review is an attempt to update the recent advances in the self-assembly of amphiphilic block and graft copolymers. Their micellization behavior is highlighted for linear AB, ABC triblock terpolymers, and graft structures in non-aqueous selective polar and non-polar solvents, including solvent mixtures and ionic liquids. The micellar characteristics, such as particle size, aggregation number, and morphology, are examined as a function of the copolymers’ architecture and molecular characteristics.

  20. A Correlation between the Activity of Candida antarctica Lipase B and Differences in Binding Free Energies of Organic Solvent and Substrate

    DEFF Research Database (Denmark)

    Banik, Sindrila Dutta; Nordblad, Mathias; Woodley, John

    2016-01-01

    in an inhibitory effect which is also confirmed by the binding free energies for the solvent and substrate molecules estimated from the simulations. Consequently, the catalytic activity of CALB decreases in polar solvents. This effect is significant, and CALB is over 10 orders of magnitude more active in nonpolar...... of the enzyme may be ascribed to binding of solvent molecules to the enzyme active site region and the solvation energy of substrate molecules in the different solvents. Polar solvent molecules interact strongly with CALB and compete with the substrate to bind to the active site region, resulting...

  1. Relaxation phenomena of polar non-polar liquid mixtures under low ...

    Indian Academy of Sciences (India)

    der high-frequency electric field have gained much importance to study the structure as ... Purohit et al [1,2] and Srivastava and Srivastava [3] had measured the real ε¼ ... The cell containing the experimental liquid in a given solvent .... due to inductive, mesomeric and electromeric effects of the substituent polar groups at-.

  2. Benchmarking Continuum Solvent Models for Keto-Enol Tautomerizations.

    Science.gov (United States)

    McCann, Billy W; McFarland, Stuart; Acevedo, Orlando

    2015-08-13

    Experimental free energies of tautomerization, ΔGT, were used to benchmark the gas-phase predictions of 17 different quantum mechanical methods and eight basis sets for seven keto-enol tautomer pairs dominated by their enolic form. The G4 method and M06/6-31+G(d,p) yielded the most accurate results, with mean absolute errors (MAE's) of 0.95 and 0.71 kcal/mol, respectively. Using these two theory levels, the solution-phase ΔGT values for 23 unique tautomer pairs composed of aliphatic ketones, β-dicarbonyls, and heterocycles were computed in multiple protic and aprotic solvents. The continuum solvation models, namely, polarizable continuum model (PCM), polarizable conductor calculation model (CPCM), and universal solvation model (SMD), gave relatively similar MAE's of ∼1.6-1.7 kcal/mol for G4 and ∼1.9-2.0 kcal/mol with M06/6-31+G(d,p). Partitioning the tautomer pairs into their respective molecular types, that is, aliphatic ketones, β-dicarbonyls, and heterocycles, and separating out the aqueous versus nonaqueous results finds G4/PCM utilizing the UA0 cavity to be the overall most accurate combination. Free energies of activation, ΔG(‡), for the base-catalyzed keto-enol interconversion of 2-nitrocyclohexanone were also computed using six bases and five solvents. The M06/6-31+G(d,p) reproduced the ΔG(‡) with MAE's of 1.5 and 1.8 kcal/mol using CPCM and SMD, respectively, for all combinations of base and solvent. That specific enolization was previously proposed to proceed via a concerted mechanism in less polar solvents but shift to a stepwise mechanism in more polar solvents. However, the current calculations suggest that the stepwise mechanism operates in all solvents.

  3. CO2-Binding Organic Liquids Gas Capture with Polarity-Swing-Assisted Regeneration Full Technology Feasibility Study B1 - Solvent-based Systems

    Energy Technology Data Exchange (ETDEWEB)

    Heldebrant, David J

    2014-08-31

    PNNL, Fluor Corporation and Queens University (Kingston, ON) successfully completed a three year comprehensive study of the CO2BOL water-lean solvent platform with Polarity Swing Assisted Regeneration (PSAR). This study encompassed solvent synthesis, characterization, environmental toxicology, physical, thermodynamic and kinetic property measurements, Aspen Plus™ modeling and bench-scale testing of a candidate CO2BOL solvent molecule. Key Program Findings The key program findings are summarized as follows: • PSAR favorably reduced stripper duties and reboiler temperatures with little/no impact to absorption column • >90% CO2 capture was achievable at reasonable liquid-gas ratios in the absorber • High rich solvent viscosities (up to 600 cP) were successfully demonstrated in the bench-scale system. However, the projected impacts of high viscosity to capital cost and operational limits compromised the other levelized cost of electricity benefits. • Low thermal conductivity of organics significantly increased the required cross exchanger surface area, and potentially other heat exchange surfaces. • CO2BOL had low evaporative losses during bench-scale testing • There was no evidence of foaming during bench scale testing • Current CO2BOL formulation costs project to be $35/kg • Ecotoxicity (Water Daphnia) was comparable between CO2BOL and MEA (169.47 versus 103.63 mg/L) • Full dehydration of the flue gas was determined to not be economically feasible. However, modest refrigeration (13 MW for the 550 MW reference system) was determined to be potentially economically feasible, and still produce a water-lean condition for the CO2BOLs (5 wt% steady-state water loading). • CO2BOLs testing with 5 wt% water loading did not compromise anhydrous performance behavior, and showed actual enhancement of CO2 capture performance. • Mass transfer of CO2BOLs was not greatly impeded by viscosity • Facile separation of antisolvent from lean CO2BOL was

  4. Solvent and ion-pairing effects on the chlorine kinetic isotope effect of t-butyl chloride

    International Nuclear Information System (INIS)

    McCord, B.R.

    1986-01-01

    The solvolysis of t-butyl chloride and 1-adamantyl chloride was measured in mixtures of aqueous 2,2,2-trifluoroethanols and in mixtures of aqueous ethanols. The KIEs for t-butyl chloride at 25 0 C in 94% TFE/water, and 60% ethanol/water (solvent mixtures with similar polarity) were 1.0097 and 1.0104 respectively. Further investigations showed a KIE of 1.0104 in 50% ethanol/water and 1.0105 in 100% ethanol while the isotope effect in the fluorinated ethanols rose from 1.0094 in 99% TFE/water to 1.0101 in 70% ethanol/water. The KIE in all these solvents were shown to be directly proportional to the nucleophilicity of the solvent and indicates nucleophilic attack on an ion pair. The similar KIE of t-butyl chloride in the ethanol/water solvents was found to support the contention that solvent polarity exerts a minimal effect on the chlorine KIE

  5. The influence of molecular architecture and solvent type on the size and structure of poly(benzyl ether) dendrimers by SANS

    NARCIS (Netherlands)

    Evmenenko, G.; Bauer, B.J.; Kleppinger, R.; Forier, B.; Dehaen, W.; Amis, E.J.; Mischenko, N.; Reynaers, H.

    2001-01-01

    The size of poly(benzyl ether) dendrimers with different molecular architectures was measured by small angle neutron scattering (SANS). Both polar and non-polar solvents were used to measure the effect of solvent type. The radius of gyration (Rg) of all of the dendrimers follows a scaling law of Rg

  6. Carbon Nanotube Dispersion in Solvents and Polymer Solutions: Mechanisms, Assembly, and Preferences.

    Science.gov (United States)

    Pramanik, Chandrani; Gissinger, Jacob R; Kumar, Satish; Heinz, Hendrik

    2017-12-26

    Debundling and dispersion of carbon nanotubes (CNTs) in polymer solutions play a major role in the preparation of carbon nanofibers due to early effects on interfacial ordering and mechanical properties. A roadblock toward ultrastrong fibers is the difficulty to achieve homogeneous dispersions of CNTs in polyacrylonitrile (PAN) and poly(methyl methacrylate) (PMMA) precursor solutions in solvents such as dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMAc), and N,N-dimethylformamide (DMF). In this contribution, molecular dynamics simulations with accurate interatomic potentials for graphitic materials that include virtual π electrons are reported to analyze the interaction of pristine single wall CNTs with the solvents and polymer solutions at 25 °C. The results explain the barriers toward dispersion of SWCNTs and quantify CNT-solvent, polymer-solvent, as well as CNT-polymer interactions in atomic detail. Debundling of CNTs is overall endothermic and unfavorable with dispersion energies of +20 to +30 mJ/m 2 in the pure solvents, + 20 to +40 mJ/m 2 in PAN solutions, and +20 to +60 mJ/m 2 in PMMA solutions. Differences arise due to molecular geometry, polar, van der Waals, and CH-π interactions. Among the pure solvents, DMF restricts CNT dispersion less due to the planar geometry and stronger van der Waals interactions. PAN and PMMA interact favorably with the pure solvents with dissolution energies of -0.7 to -1.1 kcal per mole monomer and -1.5 to -2.2 kcal per mole monomer, respectively. Adsorption of PMMA onto CNTs is stronger than that of PAN in all solvents as the molecular geometry enables more van der Waals contacts between alkyl groups and the CNT surface. Polar side groups in both polymers prefer interactions with the polar solvents. Higher polymer concentrations in solution lead to polymer aggregation via alkyl groups and reduce adsorption onto CNTs. PAN and PMMA solutions in DMSO and dilute solutions in DMF support CNT dispersion more than other

  7. Superinsulating Polyisocyanate Based Aerogels: A Targeted Search for the Optimum Solvent System.

    Science.gov (United States)

    Zhu, Zhiyuan; Snellings, Geert M B F; Koebel, Matthias M; Malfait, Wim J

    2017-05-31

    Polyisocyanate based aerogels combine ultralow thermal conductivities with better mechanical properties than silica aerogel, but these properties critically depend on the nature of the gelation solvent, perhaps more so than on any other parameter. Here, we present a systematic study of the relationship between the polyurethane-polyisocyanurate (PUR-PIR) aerogel microstructure, surface area, thermal conductivity, and density and the gelation solvent's Hansen solubility parameters for an industrially relevant PUR-PIR rigid foam formulation. We first investigated aerogels prepared in acetone-dimethyl sulfoxide (DMSO) blends and observed a minimum in thermal conductivity (λ) and maximum in specific surface area for an acetone:DMSO ratio of 85:15 v/v. We then prepared PUR-PIR aerogels in 32 different solvent blends, divided into three series with δ Dispersion , δ Polarity , and δ H-bonding fixed at 15.94, 11.30, and 7.48 MPa 1/2 , respectively, corresponding to the optimum parameters for the acetone:DMSO series. The aerogel properties display distinct dependencies on the various solubility parameters: aerogels with low thermal conductivity can be synthesized in solvents with a high δ H-bonding parameter (above 7.2) and δ Dispersion around 16.3 MPa 1/2 . In contrast, the δ Polarity parameter is of lesser importance. Our study highlights the importance of the gelation solvent, clarifies the influence of the different solvent properties, and provides a methodology for a targeted search across the solvent chemical space based on the Hansen solubility parameters.

  8. Green solvents and technologies for oil extraction from oilseeds.

    Science.gov (United States)

    Kumar, S P Jeevan; Prasad, S Rajendra; Banerjee, Rintu; Agarwal, Dinesh K; Kulkarni, Kalyani S; Ramesh, K V

    2017-01-01

    Oilseeds are crucial for the nutritional security of the global population. The conventional technology used for oil extraction from oilseeds is by solvent extraction. In solvent extraction, n -hexane is used as a solvent for its attributes such as simple recovery, non-polar nature, low latent heat of vaporization (330 kJ/kg) and high selectivity to solvents. However, usage of hexane as a solvent has lead to several repercussions such as air pollution, toxicity and harmfulness that prompted to look for alternative options. To circumvent the problem, green solvents could be a promising approach to replace solvent extraction. In this review, green solvents and technology like aqueous assisted enzyme extraction are better solution for oil extraction from oilseeds. Enzyme mediated extraction is eco-friendly, can obtain higher yields, cost-effective and aids in obtaining co-products without any damage. Enzyme technology has great potential for oil extraction in oilseed industry. Similarly, green solvents such as terpenes and ionic liquids have tremendous solvent properties that enable to extract the oil in eco-friendly manner. These green solvents and technologies are considered green owing to the attributes of energy reduction, eco-friendliness, non-toxicity and non-harmfulness. Hence, the review is mainly focussed on the prospects and challenges of green solvents and technology as the best option to replace the conventional methods without compromising the quality of the extracted products.

  9. Studies on sludge from waxy crude oil storage tank. II. Solvent fractionation

    Energy Technology Data Exchange (ETDEWEB)

    Fazal, S.A.; Zarapkar, S.S.; Joshi, G.C. [D.G. Ruparel College, Bombay (India). Dept. of Chemistry

    1995-12-31

    The sludge formed from crude oil (Bombay Hindu Crude oil) dump storage has been analysed by solvent extraction with a series of solvents of increasing polarity. The extract fractions so obtained have been analysed extensively. The nature of the sludge is compared with the similar sludges reported by other workers. 9 refs., 4 figs., 2 tabs.

  10. Solvent Extraction and Characterization of Neutral Lipids in Oocystis sp.

    Directory of Open Access Journals (Sweden)

    Renil eAnthony

    2015-01-01

    Full Text Available Microalgae are a favorable feedstock for bioproducts and biofuels due to their high oil content, fast growth rates and low resource demands. Solvent lipid extraction efficiency from microalgae is dependent on algal strain and the extraction solvent. Four non-polar extraction solvents were evaluated for the recovery of neutral cellular lipids from microalgae Oocystis sp. (UTEX LB2396. Methylene chloride, hexane, diethyl ether, and cyclohexane were selected as the extraction solvents. All solvent extracts contained hexadecanoic acid, linoleic acid and linolenic acid; accounting for 70% of total lipid content with a proportional wt% composition of the three fatty acids, except for the hexane extracts that showed only hexadecanoic acid and linoleic acid. While not statistically differentiated, methylene chloride proved to be the most effective solvent for Oocystis sp. among the four solvents tested with a total average neutral lipid recovery of 0.25% of dry weight followed by diethyl ether (0.18%, cyclohexane (0.14% and hexane (0.11%. This research presents a simple methodology to optimize the selection of lipid specific extraction solvents for the microalgal strain selected.

  11. Insights into the effects of solvent properties in graphene based electric double-layer capacitors with organic electrolytes

    Science.gov (United States)

    Zhang, Shuo; Bo, Zheng; Yang, Huachao; Yang, Jinyuan; Duan, Liangping; Yan, Jianhua; Cen, Kefa

    2016-12-01

    Organic electrolytes are widely used in electric double-layer capacitors (EDLCs). In this work, the microstructure of planar graphene-based EDLCs with different organic solvents are investigated with molecular dynamics simulations. Results show that an increase of solvent polarity could weaken the accumulation of counter-ions nearby the electrode surface, due to the screen of electrode charges and relatively lower ionic desolvation. It thus suggests that solvents with low polarity could be preferable to yield high EDL capacitance. Meanwhile, the significant effects of the size and structure of solvent molecules are reflected by non-electrostatic molecule-electrode interactions, further influencing the adsorption of solvent molecules on electrode surface. Compared with dimethyl carbonate, γ-butyrolactone, and propylene carbonate, acetonitrile with relatively small-size and linear structure owns weak non-electrostatic interactions, which favors the easy re-orientation of solvent molecules. Moreover, the shift of solvent orientation in surface layer, from parallel orientation to perpendicular orientation relative to the electrode surface, deciphers the solvent twin-peak behavior near negative electrode. The as-obtained insights into the roles of solvent properties on the interplays among particles and electrodes elucidate the solvent influences on the microstructure and capacitive behavior of EDLCs using organic electrolytes.

  12. Quantification of residual solvents in antibody drug conjugates using gas chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Medley, Colin D., E-mail: medley.colin@gene.com [Genentech Inc., Small Molecule Pharmaceutical Sciences, 1 DNA Way, South San Francisco, CA 94080 (United States); Kay, Jacob [Research Pharmaceutical Services, 520 Virginia Dr. Fort, Washington, PA (United States); Li, Yi; Gruenhagen, Jason; Yehl, Peter; Chetwyn, Nik P. [Genentech Inc., Small Molecule Pharmaceutical Sciences, 1 DNA Way, South San Francisco, CA 94080 (United States)

    2014-11-19

    Highlights: • Sensitive residual solvents detection in ADCs. • 125 ppm QL for common conjugation solvents. • Generic and validatable method. - Abstract: The detection and quantification of residual solvents present in clinical and commercial pharmaceutical products is necessary from both patient safety and regulatory perspectives. Head-space gas chromatography is routinely used for quantitation of residual solvents for small molecule APIs produced through synthetic processes; however residual solvent analysis is generally not needed for protein based pharmaceuticals produced through cultured cell lines where solvents are not introduced. In contrast, antibody drug conjugates and other protein conjugates where a drug or other molecule is covalently bound to a protein typically use solvents such as N,N-dimethylacetamide (DMA), N,N‑dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or propylene glycol (PG) to dissolve the hydrophobic small molecule drug for conjugation to the protein. The levels of the solvent remaining following the conjugation step are therefore important to patient safety as these parental drug products are introduced directly into the patients bloodstream. We have developed a rapid sample preparation followed by a gas chromatography separation for the detection and quantification of several solvents typically used in these conjugation reactions. This generic method has been validated and can be easily implemented for use in quality control testing for clinical or commercial bioconjugated products.

  13. The effect of solvents on the stabilities (color and Fe) of anthocyanin isolated from the red-color-melinjo peels

    Energy Technology Data Exchange (ETDEWEB)

    Tarmizi, Ermiziar, E-mail: uph-ermi@yahoo.com, E-mail: ermitarmizi@gmail.com; Saragih, Raskita, E-mail: raskitasaragih@yahoo.com [Indonesia Institute of Technology (ITI), Raya PuspiptekSerpong, Tangerang Banten 15320 (Indonesia); Lalasari, Latifa Hanum, E-mail: ifa-sari@yahoo.com, E-mail: lati003@lipi.go.id [Research Centre for Metallurgy and Material, Indonesian Institute of Sciences (LIPI), KawasanPuspiptekSerpong, Tangerang Selatan 15314 (Indonesia)

    2015-12-29

    Anthocyanin from the red-color-melinjo peels could be isolated using a polar solvent (ethanol) [ermiziar, 2010]. The amount of hydrocarbons in the structure of anthocyanin might cause that anthocyanin could be isolated using a non polar solvent. The purpose of research is to isolate anthocyanin using non polar solvents (hexane and petroleum ether) with maceration steps for 24 hours and separate solvents using rotary evaporator equipment. The stability of anthocyanin could be observed every week (1,2,3 and 4 weeks) in various environmental conditions (with or without light in refrigerator and open or closed storage). The characterization of anthocyanin was analyzed with visual (physic photo) and or using equipments such as Fourier Transform Infrared Spectroscopy (FTIR) for determining functional groups, Ultraviolet–Visible Spectroscopy (UV/Vis) with 500-550 nm wavelengths for deciding absorption of anthocyanin and atomic absorption spectroscopy (AAS) for analyzing Fe element. The result showed that anthocyanin isolation with hexane solvent has yield higher than petroleum eter solvent. From the results of physic observation for 4 weeks looked that there are changing colors of samples significant after 3 and 4 weeks in cooler with or without light. The stability of anthocyanin color was the best on the storage time until 2 weeks using hexane solvent in refrigerator and closed condition that it has absorption of 0.6740 with 500 nm wavelengths and Fe concentration 6.29 ppm.

  14. The effect of solvents on the stabilities (color and Fe) of anthocyanin isolated from the red-color-melinjo peels

    International Nuclear Information System (INIS)

    Tarmizi, Ermiziar; Saragih, Raskita; Lalasari, Latifa Hanum

    2015-01-01

    Anthocyanin from the red-color-melinjo peels could be isolated using a polar solvent (ethanol) [ermiziar, 2010]. The amount of hydrocarbons in the structure of anthocyanin might cause that anthocyanin could be isolated using a non polar solvent. The purpose of research is to isolate anthocyanin using non polar solvents (hexane and petroleum ether) with maceration steps for 24 hours and separate solvents using rotary evaporator equipment. The stability of anthocyanin could be observed every week (1,2,3 and 4 weeks) in various environmental conditions (with or without light in refrigerator and open or closed storage). The characterization of anthocyanin was analyzed with visual (physic photo) and or using equipments such as Fourier Transform Infrared Spectroscopy (FTIR) for determining functional groups, Ultraviolet–Visible Spectroscopy (UV/Vis) with 500-550 nm wavelengths for deciding absorption of anthocyanin and atomic absorption spectroscopy (AAS) for analyzing Fe element. The result showed that anthocyanin isolation with hexane solvent has yield higher than petroleum eter solvent. From the results of physic observation for 4 weeks looked that there are changing colors of samples significant after 3 and 4 weeks in cooler with or without light. The stability of anthocyanin color was the best on the storage time until 2 weeks using hexane solvent in refrigerator and closed condition that it has absorption of 0.6740 with 500 nm wavelengths and Fe concentration 6.29 ppm

  15. Intramolecular, Exciplex-Mediated, Proton-Coupled, Charge-Transfer Processes in N,N-Dimethyl-3-(1-pyrenyl)propan-1-ammonium Cations: Influence of Anion, Solvent Polarity, and Temperature.

    Science.gov (United States)

    Safko, Trevor M; Faleiros, Marcelo M; Atvars, Teresa D Z; Weiss, Richard G

    2016-06-16

    An intramolecular exciplex-mediated, proton-coupled, charge-transfer (PCCT) process has been investigated for a series of N,N-dimethyl-3-(1-pyrenyl)propan-1-ammonium cations with different anions (PyS) in solvents of low to intermediate polarity over a wide temperature range. Solvent mediates both the equilibrium between conformations of the cation that place the pyrenyl and ammonium groups in proximity (conformation C) or far from each other (conformation O) and the ability of the ammonium group to transfer a proton adiabatically in the PyS excited singlet state. Thus, exciplex emission, concurrent with the PCCT process, was observed only in hydrogen-bond accepting solvents of relatively low polarity (tetrahydrofuran, ethyl acetate, and 1,4-dioxane) and not in dichloromethane. From the exciplex emission and other spectroscopic and thermodynamic data, the acidity of the ammonium group in conformation C of the excited singlet state of PyS (pKa*) has been estimated to be ca. -3.4 in tetrahydrofuran. The ratios between the intensities of emission from the exciplex and the locally excited state (IEx/ILE) appear to be much more dependent on the nature of the anion than are the rates of exciplex formation and decay, although the excited state data do not provide a quantitative measure of the anion effect on the C-O equilibrium. The activation energies associated with exciplex formation in THF are calculated to be 0.08 to 0.15 eV lower than for the neutral amine, N,N-dimethyl-3-(1-pyrenyl)propan-1-amine. Decay of the exciplexes formed from the deprotonation of PyS is hypothesized to occur through charge-recombination processes. To our knowledge, this is the first example in which photoacidity and intramolecular exciplex formation (i.e., a PCCT reaction) are coupled.

  16. Solvent effects on extraction of polycyclic aromatic hydrocarbons in ambient aerosol samples

    Directory of Open Access Journals (Sweden)

    Flasch Mira

    2016-01-01

    Full Text Available Polycyclic Aromatic Hydrocarbons (PAHs in the ambient particulate matter pose one of the most important issues in the focus of environmental management. The concentration of their representative, Benzo(apyrene (BaP, undergoes limitations according to European Union directive. However, a successful control over the pollution levels and their sources is limited by the high uncertainty of analytical and statistical approaches used for their characterization. Here we compare differences in PAH concentrations related to the use of different solvents in the course of ultrasonic extraction of a certified reference material (PM10-like PAH mixture and filter samples of ambient particulate matter collected in Austria for the CG-MS PAH analysis. Using solvents of increasing polarity: Cyclohexane (0,006, Toluene (0,099, Dichloromethane (0,309, Acetone (0,43 and Acetonitrile (0,460, as well as mixtures of those, filters representing high and low concentrations of particulate matter were investigated. Although some scatter of the obtained concentrations was observed no trend related to the polarity of the solvent became visible. Regarding the reproducibility, which can be expected of PAH analysis no significant difference between the different solvents was determined. This result is valid for all compounds under investigation.

  17. Photonic crystal based sensor for organic solvents and for solvent-water mixtures.

    Science.gov (United States)

    Fenzl, Christoph; Hirsch, Thomas; Wolfbeis, Otto S

    2012-12-12

    Monodisperse polystyrene nanoparticles with a diameter of 173 nm were incorporated into a polydimethylsiloxane matrix where they display an iridescent color that can be attributed to the photonic crystal effect. The film is of violet color if placed in plain water, but turns to red in the presence of the non-polar solvent n-hexane. Several solvents were studied in some detail. We show that such films are capable of monitoring the water content of ethanol/water mixtures, where only 1% (v/v) of water leads to a shift of the peak wavelength of reflected light by 5 nm. The method also can be applied to determine, both visually and instrumentally, the fraction of methanol in ethanol/methanol mixtures. Here, a fraction of 1% of methanol (v/v) results in a wavelength shift of 2 nm. The reflected wavelength is not influenced by temperature changes nor impeded by photobleaching. The signal changes are fully reversible and response times are <1 s.

  18. Photonic Crystal Based Sensor for Organic Solvents and for Solvent-Water Mixtures

    Directory of Open Access Journals (Sweden)

    Otto S. Wolfbeis

    2012-12-01

    Full Text Available Monodisperse polystyrene nanoparticles with a diameter of 173 nm were incorporated into a polydimethylsiloxane matrix where they display an iridescent color that can be attributed to the photonic crystal effect. The film is of violet color if placed in plain water, but turns to red in the presence of the non-polar solvent n-hexane. Several solvents were studied in some detail. We show that such films are capable of monitoring the water content of ethanol/water mixtures, where only 1% (v/v of water leads to a shift of the peak wavelength of reflected light by 5 nm. The method also can be applied to determine, both visually and instrumentally, the fraction of methanol in ethanol/methanol mixtures. Here, a fraction of 1% of methanol (v/v results in a wavelength shift of 2 nm. The reflected wavelength is not influenced by temperature changes nor impeded by photobleaching. The signal changes are fully reversible and response times are <1 s.

  19. Xerogel p-anisidinapropilsílica: estudo da estabilidade térmica e da resistência à lixiviação com solventes p-anisidinepropylsilica xerogel: thermal stability and resistance to leaching by solvents

    Directory of Open Access Journals (Sweden)

    Leonardo Franken

    2002-07-01

    Full Text Available The xerogel p-anisidinepropylsilica was obtained. This solid presents some residual paraffin and also a small fraction of high organofunctionalized material that was leached in polar solvent. The xerogel purification could be achieved by exhaustively washing with hexane and dichloromethane solvents, or submitting the xerogel to thermal treatment up to 300 ºC, in vacuum. The resulting purified xerogel material present an appreciable thermal stability and resistance to leaching by solvents.

  20. Solvent Extraction and Characterization of Neutral Lipids in Oocystis sp

    Energy Technology Data Exchange (ETDEWEB)

    Anthony, Renil [Department of Mechanical Engineering, Ohio University, Athens, OH (United States); Stuart, Ben, E-mail: stuart@ohio.edu [Department of Civil Engineering, Ohio University, Athens, OH (United States)

    2015-01-20

    Microalgae are a favorable feedstock for bioproducts and biofuels due to their high oil content, fast growth rates, and low resource demands. Solvent lipid extraction efficiency from microalgae is dependent on algal strain and the extraction solvent. Four non-polar extraction solvents were evaluated for the recovery of neutral cellular lipids from microalgae Oocystis sp. (University of Texas at Austin LB2396). Methylene chloride, hexane, diethyl ether, and cyclohexane were selected as the extraction solvents. The lipid extracts were derivatized and analyzed using gas chromatography–mass spectroscopy. All solvent extracts contained hexadecanoic acid, linoleic acid, and linolenic acid; accounting for 70% of total lipid content with a proportional wt% composition of the three fatty acids, except for the hexane extracts that showed only hexadecanoic acid and linoleic acid. While not statistically differentiated, methylene chloride proved to be the most effective solvent for Oocystis sp. among the four solvents tested with a total average neutral lipid recovery of 0.25% of dry weight followed by diethyl ether (0.18%), cyclohexane (0.14%), and hexane (0.11%). This research presents a simple methodology to optimize the selection of lipid specific extraction solvents for the microalgal strain selected.

  1. Solvent Extraction and Characterization of Neutral Lipids in Oocystis sp

    International Nuclear Information System (INIS)

    Anthony, Renil; Stuart, Ben

    2015-01-01

    Microalgae are a favorable feedstock for bioproducts and biofuels due to their high oil content, fast growth rates, and low resource demands. Solvent lipid extraction efficiency from microalgae is dependent on algal strain and the extraction solvent. Four non-polar extraction solvents were evaluated for the recovery of neutral cellular lipids from microalgae Oocystis sp. (University of Texas at Austin LB2396). Methylene chloride, hexane, diethyl ether, and cyclohexane were selected as the extraction solvents. The lipid extracts were derivatized and analyzed using gas chromatography–mass spectroscopy. All solvent extracts contained hexadecanoic acid, linoleic acid, and linolenic acid; accounting for 70% of total lipid content with a proportional wt% composition of the three fatty acids, except for the hexane extracts that showed only hexadecanoic acid and linoleic acid. While not statistically differentiated, methylene chloride proved to be the most effective solvent for Oocystis sp. among the four solvents tested with a total average neutral lipid recovery of 0.25% of dry weight followed by diethyl ether (0.18%), cyclohexane (0.14%), and hexane (0.11%). This research presents a simple methodology to optimize the selection of lipid specific extraction solvents for the microalgal strain selected.

  2. Influence of Solvent-Solvent and Solute-Solvent Interaction Properties on Solvent-Mediated Potential

    International Nuclear Information System (INIS)

    Zhou Shiqi

    2005-01-01

    A recently proposed universal calculational recipe for solvent-mediated potential is applied to calculate excess potential of mean force between two large Lennard-Jones (LJ) or hard core attractive Yukawa particles immersed in small LJ solvent bath at supercritical state. Comparison between the present prediction with a hypernetted chain approximation adopted for solute-solute correlation at infinitely dilute limit and existing simulation data shows high accuracy for the region with large separation, and qualitative reliability for the solute particle contact region. The calculational simplicity of the present recipe allows for a detailed investigation on the effect of the solute-solvent and solvent-solvent interaction details on the excess potential of mean force. The resultant conclusion is that gathering of solvent particles near a solute particle leads to repulsive excess PMF, while depletion of solvent particles away from the solute particle leads to attractive excess PMF, and minor change of the solvent-solvent interaction range has large influence on the excess PMF.

  3. Determination and correlation of the solubility for diosgenin in alcohol solvents

    International Nuclear Information System (INIS)

    Chen Feixiong; Zhao Mingrui; Liu Chuochuo; Peng Feifei; Ren Baozeng

    2012-01-01

    Highlights: ► The solubilities of diosgenin in different alcohols solvents have been obtained. ► The solubility decreases with the increase of the polarity of the alcohols solvents. ► The results show that the three models agree well with the experimental data. - Abstract: Using a laser monitoring technique, the solubility of diosgenin in ethanol, 1-propanol, 1-butanol, isobutyl alcohol, tert-butanol, 1-pentanol, and iso-octyl alcohol was measured over the temperature range from (290.15 to 330.15) K at atmospheric pressure. Its corresponding (solid + liquid) equilibrium data will provide essential support for industrial design and further theoretical studies. From the experimental results, the solubility of diosgenin in ethanol, 1-propanol, 1-butanol, isobutyl alcohol, tert-butanol, 1-pentanol, and iso-octyl alcohol was found to increase with increasing temperature and decrease with the increase of the polarity of the alcohols solvents. The Apelblat equation, the ideal model and the λh equation were used to correlate the solubility values. The results showed that the three models mentioned above agreed well with the experimental data.

  4. Action of solvents on torbanite and the nature of extracted products

    Energy Technology Data Exchange (ETDEWEB)

    Dulhunty, J A

    1943-01-01

    Tests were made on torbanite with polar and nonpolar solvents under various conditions. Torbanite undergoes no change when heated below 250/sup 0/C, but depolymerization of the organic matter, absorption of solvent, and swelling and softening of the torbanite occurred between 250 and 300/sup 0/C, although no appreciable quantity of soluble product was formed. Between 300 and 350/sup 0/C depolymerization continued and more solvent was absorbed, which caused swelling, softening, and partial breakdown of the physical structure of torbanite. The intimate mixture of torbanite and solvent produced a jellylike mass, which could not be filtered. Continued heating between 350 and 400/sup 0/C caused the organic matter to dissolve in the solvent and produced a complete breakdown in the physical structure of the torbanite. The extracts consisted largely of heavy paraffin compounds, including waxes.

  5. Solvent-dependent excited-state hydrogen transfer and intersystem crossing in 2-(2′-hydroxyphenyl)-benzothiazole

    KAUST Repository

    Aly, Shawkat Mohammede

    2015-02-12

    The excited-state intramolecular hydrogen transfer (ESIHT) of 2-(2′-hydroxyphenyl) benzothiazole (HBT) has been investigated in a series of nonpolar, polar aprotic, and polar protic solvents. A variety of state-of-the-art experimental methods were employed, including femto- and nanosecond transient absorption and fluorescence upconversion spectroscopy with broadband capabilities. We show that the dynamics and mechanism of ESIHT of the singlet excited HBT are strongly solvent-dependent. In nonpolar solvents, the data demonstrate that HBT molecules adopt a closed form stabilized by O-H⋯N chelated hydrogen bonds with no twisting angle, and the photoinduced H transfer occurs within 120 fs, leading to the formation of a keto tautomer. In polar solvents, owing to dipole-dipole cross talk and hydrogen bonding interactions, the H transfer process is followed by ultrafast nonradiative deactivation channels, including ultrafast internal conversion (IC) and intersystem crossing (ISC). This is likely to be driven by the twisting motion around the C-C bond between the hydroxyphenyl and thiazole moieties, facilitating the IC back to the enol ground state or to the keto triplet state. In addition, our femtosecond time-resolved fluorescence experiments indicate, for the first time, that the lifetime of the enol form in ACN is approximately 280 fs. This observation indicates that the solvent plays a crucial role in breaking the H bond and deactivating the excited state of the HBT. Interestingly, the broadband transient absorption and fluorescence up-conversion data clearly demonstrate that the intermolecular proton transfer from the excited HBT to the DMSO solvent is about 190 fs, forming the HBT anion excited state.

  6. Solvent-dependent excited-state hydrogen transfer and intersystem crossing in 2-(2′-hydroxyphenyl)-benzothiazole

    KAUST Repository

    Aly, Shawkat Mohammede; Usman, Anwar; Alzayer, Maytham; Hamdi, Ghada A.; Alarousu, Erkki; Mohammed, Omar F.

    2015-01-01

    The excited-state intramolecular hydrogen transfer (ESIHT) of 2-(2′-hydroxyphenyl) benzothiazole (HBT) has been investigated in a series of nonpolar, polar aprotic, and polar protic solvents. A variety of state-of-the-art experimental methods were employed, including femto- and nanosecond transient absorption and fluorescence upconversion spectroscopy with broadband capabilities. We show that the dynamics and mechanism of ESIHT of the singlet excited HBT are strongly solvent-dependent. In nonpolar solvents, the data demonstrate that HBT molecules adopt a closed form stabilized by O-H⋯N chelated hydrogen bonds with no twisting angle, and the photoinduced H transfer occurs within 120 fs, leading to the formation of a keto tautomer. In polar solvents, owing to dipole-dipole cross talk and hydrogen bonding interactions, the H transfer process is followed by ultrafast nonradiative deactivation channels, including ultrafast internal conversion (IC) and intersystem crossing (ISC). This is likely to be driven by the twisting motion around the C-C bond between the hydroxyphenyl and thiazole moieties, facilitating the IC back to the enol ground state or to the keto triplet state. In addition, our femtosecond time-resolved fluorescence experiments indicate, for the first time, that the lifetime of the enol form in ACN is approximately 280 fs. This observation indicates that the solvent plays a crucial role in breaking the H bond and deactivating the excited state of the HBT. Interestingly, the broadband transient absorption and fluorescence up-conversion data clearly demonstrate that the intermolecular proton transfer from the excited HBT to the DMSO solvent is about 190 fs, forming the HBT anion excited state.

  7. Electronic excitations in a dielectric continuum solvent with quantum Monte Carlo: Acrolein in water

    International Nuclear Information System (INIS)

    Floris, Franca Maria; Amovilli, Claudio; Filippi, Claudia

    2014-01-01

    We investigate here the vertical n → π * and π → π * transitions of s-trans-acrolein in aqueous solution by means of a polarizable continuum model (PCM) we have developed for the treatment of the solute at the quantum Monte Carlo (QMC) level of the theory. We employ the QMC approach which allows us to work with highly correlated electronic wave functions for both the solute ground and excited states and, to study the vertical transitions in the solvent, adopt the commonly used scheme of considering fast and slow dielectric polarization. To perform calculations in a non-equilibrium solvation regime for the solute excited state, we add a correction to the global dielectric polarization charge density, obtained self consistently with the solute ground-state wave function by assuming a linear-response scheme. For the solvent polarization in the field of the solute in the ground state, we use the static dielectric constant while, for the electronic dielectric polarization, we employ the solvent refractive index evaluated at the same frequency of the photon absorbed by the solute for the transition. This choice is shown to be better than adopting the most commonly used value of refractive index measured in the region of visible radiation. Our QMC calculations show that, for standard cavities, the solvatochromic shifts obtained with the PCM are underestimated, even though of the correct sign, for both transitions of acrolein in water. Only by reducing the size of the cavity to values where more than one electron is escaped to the solvent region, we regain the experimental shift for the n → π * case and also improve considerably the shift for the π → π * transition

  8. Electronic excitations in a dielectric continuum solvent with quantum Monte Carlo: Acrolein in water

    Science.gov (United States)

    Floris, Franca Maria; Filippi, Claudia; Amovilli, Claudio

    2014-01-01

    We investigate here the vertical n → π* and π → π* transitions of s-trans-acrolein in aqueous solution by means of a polarizable continuum model (PCM) we have developed for the treatment of the solute at the quantum Monte Carlo (QMC) level of the theory. We employ the QMC approach which allows us to work with highly correlated electronic wave functions for both the solute ground and excited states and, to study the vertical transitions in the solvent, adopt the commonly used scheme of considering fast and slow dielectric polarization. To perform calculations in a non-equilibrium solvation regime for the solute excited state, we add a correction to the global dielectric polarization charge density, obtained self consistently with the solute ground-state wave function by assuming a linear-response scheme. For the solvent polarization in the field of the solute in the ground state, we use the static dielectric constant while, for the electronic dielectric polarization, we employ the solvent refractive index evaluated at the same frequency of the photon absorbed by the solute for the transition. This choice is shown to be better than adopting the most commonly used value of refractive index measured in the region of visible radiation. Our QMC calculations show that, for standard cavities, the solvatochromic shifts obtained with the PCM are underestimated, even though of the correct sign, for both transitions of acrolein in water. Only by reducing the size of the cavity to values where more than one electron is escaped to the solvent region, we regain the experimental shift for the n → π* case and also improve considerably the shift for the π → π* transition.

  9. Produced Water Treatment Using the Switchable Polarity Solvent Forward Osmosis (SPS FO) Desalination Process: Preliminary Engineering Design Basis

    Energy Technology Data Exchange (ETDEWEB)

    Wendt, Daniel; Adhikari, Birendra; Orme, Christopher; Wilson, Aaron

    2016-05-01

    Switchable Polarity Solvent Forward Osmosis (SPS FO) is a semi-permeable membrane-based water treatment technology. INL is currently advancing SPS FO technology such that a prototype unit can be designed and demonstrated for the purification of produced water from oil and gas production operations. The SPS FO prototype unit will used the thermal energy in the produced water as a source of process heat, thereby reducing the external process energy demands. Treatment of the produced water stream will reduce the volume of saline wastewater requiring disposal via injection, an activity that is correlated with undesirable seismic events, as well as generate a purified product water stream with potential beneficial uses. This paper summarizes experimental data that has been collected in support of the SPS FO scale-up effort, and describes how this data will be used in the sizing of SPS FO process equipment. An estimate of produced water treatment costs using the SPS FO process is also provided.

  10. The Case for Tetrahedral Oxy-subhydride (TOSH Structures in the Exclusion Zones of Anchored Polar Solvents Including Water

    Directory of Open Access Journals (Sweden)

    Klaus Oehr

    2014-11-01

    Full Text Available We hypothesize a mechanistic model of how negatively-charged exclusion zones (EZs are created. While the growth of EZs is known to be associated with the absorption of ambient photonic energy, the molecular dynamics giving rise to this process need greater elucidation. We believe they arise due to the formation of oxy-subhydride structures (OH−(H2O4 with a tetrahedral (sp3 (OH−(H2O3 core. Five experimental data sets derived by previous researchers were assessed in this regard: (1 water-derived EZ light absorbance at specific infrared wavelengths, (2 EZ negative potential in water and ethanol, (3 maximum EZ light absorbance at 270 nm ultraviolet wavelength, (4 ability of dimethyl sulphoxide but not ether to form an EZ, and (5 transitory nature of melting ice derived EZs. The proposed tetrahedral oxy-subhydride structures (TOSH appear to adequately account for all of the experimental evidence derived from water or other polar solvents.

  11. Solvent accessible surface area (ASA) of simulated phospholipid membranes

    DEFF Research Database (Denmark)

    Tuchsen, E.; Jensen, Morten Østergaard; Westh, P.

    2003-01-01

    The membrane-solvent interface has been investigated through calculations of the solvent accessible surface area (ASA) for simulated membranes of DPPC and POPE. For DPPC at 52 degreesC we found an ASA of 126 +/- 8 Angstrom(2) per lipid molecule, equivalent to twice the projected lateral area......, even the most exposed parts of the PC head-group show average ASAs of less than half of its maximal or 'fully hydrated' value. The average ASA of a simulated POPE membrane was 96 +/- 7 Angstrom(2) per lipid. The smaller value than for DPPC reflects much lower ASA of the ammonium ion, which is partially...... compensated by increased exposure of the ethylene and phosphate moieties. The ASA of the polar moieties Of (PO4, NH3 and COO) constitutes 65% of the total accessible area for POPE, making this interface more polar than that of DPPC. It is suggested that ASA information can be valuable in attempts...

  12. Is Water a Universal Solvent for Life?

    Science.gov (United States)

    Pohorill, Andrew

    2012-01-01

    There are strong reasons to believe that the laws, principles and constraints of physics and chemistry are universal. It is much less clear how this universality translates into our understanding of the origins of life. Conventionally, discussions of this topic focus on chemistry that must be sufficiently rich to seed life. Although this is clearly a prerequisite for the emergence of living systems, I propose to focus instead on self-organization of matter into functional structures capable of reproduction, evolution and responding to environmental changes. In biology, most essential functions are largely mediated by noncovalent interactions (interactions that do not involve making or breaking chemical bonds). Forming chemical bonds is only a small part of what living systems do. There are specific implications of this point of view for universality. I will concentrate on one of these implications. Strength of non-covalent interactions must be properly tuned. If they were too weak, the system would exhibit undesired, uncontrolled response to natural fluctuations of physical and chemical parameters. If they were too strong kinetics of biological processes would be slow and energetics costly. This balance, however, is not a natural property of complex chemical systems. Instead, it has to be achieved with the aid of an appropriate solvent for life. In particular, potential solvents for life must be characterized by a high dielectric constant to ensure solubility of polar species and sufficient flexibility of biological structures stabilized by electrostatic interactions. Among these solvents, water exhibits a remarkable trait that it also promotes solvophobic (hydrophobic) interactions between non-polar species, typically manifested by a tendency of these species to aggregate and minimize their contacts with the aqueous solvent. Hydrophobic interactions are responsible, at least in part, for many self-organization phenomena in biological systems, such as the formation

  13. Solvent/oxidant-switchable synthesis of multisubstituted quinazolines and benzimidazoles via metal-free selective oxidative annulation of arylamidines.

    Science.gov (United States)

    Lin, Jian-Ping; Zhang, Feng-Hua; Long, Ya-Qiu

    2014-06-06

    A fast and simple divergent synthesis of multisubstituted quinazolines and benzimidazoles was developed from readily available amidines, via iodine(III)-promoted oxidative C(sp(3))-C(sp(2)) and C(sp(2))-N bond formation in nonpolar and polar solvents, respectively. Further selective synthesis of quinazolines in polar solvent was realized by TEMPO-catalyzed sp(3)C-H/sp(2)C-H direct coupling of the amidine with K2S2O8 as the oxidant. No metal, base, or other additives were needed.

  14. Cooling crystallization of Indomethacin from different organic solvents

    DEFF Research Database (Denmark)

    Malwade, Chandrakant Ramkrishna; Qu, Haiyan

    , 25, 35, and 45 °C. The solvents with varying polarities (ethanol, methanol, ethyl acetate, acetone, acetonitrile, and dichloromethane) were used for solubility measurement. Maximum solubility of IMC was observed in acetone, while acetonitrile showed the lowest solubility. Solid phase analysis...... of excess solute with XRPD and Raman spectroscopy confirmed formation of IMC solvate in acetone, methanol and dichloromethane at 15 °C. Based on solubility of IMC, the solvents ethanol, ethyl acetate, acetone, and dichloromethane were selected for crystallization experiments. Nucleation kinetics of IMC...... in selected solvents was investigated through the measurement of induction time at 5 °C and 15 °C. Longer induction times were observed for IMC in ethanol at both temperatures compared to the one in acetone. Metastable α form of IMC was obtained from ethanol, while solvate of IMC was produced from acetone....

  15. Measurement of dielectric constant of organic solvents by indigenously developed dielectric probe

    Science.gov (United States)

    Keshari, Ajay Kumar; Rao, J. Prabhakar; Rao, C. V. S. Brahmmananda; Ramakrishnan, R.; Ramanarayanan, R. R.

    2018-04-01

    The extraction, separation and purification of actinides (uranium and plutonium) from various matrices are an important step in nuclear fuel cycle. One of the separation process adopted in an industrial scale is the liquid-liquid extraction or solvent extraction. Liquid-liquid extraction uses a specific ligand/extractant in conjunction with suitable diluent. Solvent extraction or liquid-liquid extraction, involves the partitioning of the solute between two immiscible phases. In most cases, one of the phases is aqueous, and the other one is an organic solvent. The solvent used in solvent extraction should be selective for the metal of interest, it should have optimum distribution ratio, and the loaded metal from the organic phase should be easily stripped under suitable experimental conditions. Some of the important physical properties which are important for the solvent are density, viscosity, phase separation time, interfacial surface tension and the polarity of the extractant.

  16. Microwave-assisted extraction and accelerated solvent extraction with ethyl acetate-cyclohexane before determination of organochlorines in fish tissue by gas chromatography with electron-capture detection.

    Science.gov (United States)

    Weichbrodt, M; Vetter, W; Luckas, B

    2000-01-01

    Focused open-vessel microwave-assisted extraction (FOV-MAE), closed-vessel microwave-assisted extraction (CV-MAE), and accelerated solvent extraction (ASE) were used for extraction before determination of organochlorine compounds (polychlorinated biphenyls, DDT, toxaphene, chlordane, hexachlorobenzene, hexachlorocyclohexanes, and dieldrin) in cod liver and fish fillets. Wet samples were extracted without the time-consuming step of lyophilization or other sample-drying procedures. Extractions were performed with the solvent mixture ethyl acetate-cyclohexane (1 + 1, v/v), which allowed direct use of gel-permeation chromatography without solvent exchange. For FOV-MAE, the solvent mixture removed water from the sample matrix via azeotropic distillation. The status of water removal was controlled during extraction by measuring the temperature of the distillate. After water removal, the temperature of the distillate increased and the solvent mixture became less polar. Only the pure extraction solvent allowed quantitative extraction of the organochlorine compounds. For CV-MAE, water could not be separated during the extraction. For this reason, the extraction procedure for wet fish tissue required 2 extraction steps: the first for manual removal of coextracted water, and the second for quantitative extraction of the organochlorine compounds with the pure solvent. Therefore, CV-MAE is less convenient for samples with high water content. For ASE, water in the sample was bound with Na2SO4. The reproducibility for each technique was very good (relative standard deviation was typically <10%); the slightly varying levels were attributed to deviations during sample cleanup and the generally low levels.

  17. The Effect of Solvents, Acetone, Water, and Ethanol, on the Morphological and Optical Properties of ZnO Nanoparticles Prepared by Microwave

    Directory of Open Access Journals (Sweden)

    Phindile B. Khoza

    2012-01-01

    Full Text Available HDA-capped ZnO nanoparticles were prepared by solvothermal method using solvents of different polarities. A number of parameters were kept constant such as temperature, pressure, time, and pH while solvents were varied, that is, water, ethanol, and acetone. The TEM was used for the structural properties and morphologies such as spheres, mixture of rods, and spheres and stars were obtained in ethanol, acetone, and water, respectively, in a given reaction time of 15 minutes. Both ethanol and acetone gave rods with high aspect ratio primarily because of the lengths of the rods. Water and ethanol have the hydroxyl groups which interact with nanoparticles from nucleation, growth, and termination giving rise to nonspherical shapes. The hydroxyl group promotes growth in a nonuniform way resulting in stars and rods. The optical features were typical of ZnO nanoparticles with excitonic peaks in the range 368 to 374 nm from their absorption spectra. The XRD patterns of the particles gave the most stable form of ZnO which is the hexagonal phase, with high degree of crystallinity and with the 101 plane predominant in all solvents.

  18. System and process for polarity swing assisted regeneration of gas selective capture liquids

    Science.gov (United States)

    Heldebrant, David J.; Tegrotenhuis, Ward E.; Freeman, Charles J.; Elliott, Michael L.; Koech, Phillip K.; Humble, Paul H.; Zheng, Feng; Zhang, Jian

    2017-07-18

    A polarity swing-assisted regeneration (PSAR) process is disclosed for improving the efficiency of releasing gases chemically bound to switchable ionic liquids. Regeneration of the SWIL involves addition of a quantity of non-polar organic compound as an anti-solvent to destabilize the SWIL, which aids in release of the chemically bound gas. The PSAR decreases gas loading of a SWIL at a given temperature and increases the rate of gas release compared to heating in the absence of anti-solvent.

  19. Solubility and crystallization of piroxicam from different solvents in evaporative and cooling crystallizations

    DEFF Research Database (Denmark)

    Qu, Haiyan; Ostergaard, Iben

    2018-01-01

    polarities; It has been found that the solubility of piroxicam in the solvents is in the following order: chloroform > dichloromethane > acetone > ethyl acetate > acetonitrile > acetic acid > methanol > hexane. Crystallization of piroxicam from different solvents has been performed with evaporative.......Results obtained in the present work showed the stochastic nature of nucleation of different polymorphs as well as the complexity of the crystallization of a polymorphic system....

  20. Tolerance of anaerobic bacteria to chlorinated solvents.

    Science.gov (United States)

    Koenig, Joanna C; Groissmeier, Kathrin D; Manefield, Mike J

    2014-01-01

    The aim of this research was to evaluate the effects of four chlorinated aliphatic hydrocarbons (CAHs), perchloroethene (PCE), carbon tetrachloride (CT), chloroform (CF) and 1,2-dichloroethane (1,2-DCA), on the growth of eight anaerobic bacteria: four fermentative species (Escherichia coli, Klebsiella sp., Clostridium sp. and Paenibacillus sp.) and four respiring species (Pseudomonas aeruginosa, Geobacter sulfurreducens, Shewanella oneidensis and Desulfovibrio vulgaris). Effective concentrations of solvents which inhibited growth rates by 50% (EC50) were determined. The octanol-water partition coefficient or log Po/w of a CAH proved a generally satisfactory measure of its toxicity. Most species tolerated approximately 3-fold and 10-fold higher concentrations of the two relatively more polar CAHs CF and 1,2-DCA, respectively, than the two relatively less polar compounds PCE and CT. EC50 values correlated well with growth rates observed in solvent-free cultures, with fast-growing organisms displaying higher tolerance levels. Overall, fermentative bacteria were more tolerant to CAHs than respiring species, with iron- and sulfate-reducing bacteria in particular appearing highly sensitive to CAHs. These data extend the current understanding of the impact of CAHs on a range of anaerobic bacteria, which will benefit the field of bioremediation.

  1. Collapse in two good solvents, swelling in two poor solvents: defying the laws of polymer solubility?

    Science.gov (United States)

    Mukherji, Debashish; Marques, Carlos M; Kremer, Kurt

    2018-01-17

    In this work we discuss two mirror but distinct phenomena of polymer paradoxical properties in mixed solvents: co-non-solvency and co-solvency. When a polymer collapses in a mixture of two miscible good solvents the phenomenon is known as co-non-solvency, while co-solvency is a phenomenon that is associated with the swelling of a polymer in poor solvent mixtures. A typical example of co-non-solvency is provided by poly(N-isopropylacrylamide) in aqueous alcohol, while poly(methyl methacrylate) in aqueous alcohol shows co-solvency. We discuss these two phenomena to compare their microscopic origins and show that both can be understood within generic universal concepts. A broad range of polymers is therefore expected to exhibit these phenomena where specific chemical details play a lesser role than the appropriate combination of interactions between the trio of molecular components.

  2. High temperature solvent extraction of oil shale and bituminous coal using binary solvent mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Goetz, G.K.E. [Lehrstuhl fuer Geologie, Geochemie und Lagerstaetten des Erdoels und der Kohle, RWTH Aachen (Germany)

    1997-12-31

    A high volatile bituminous coal from the Saar Basin and an oil shale from the Messel deposit, both Germany, were extracted with binary solvent mixtures using the Advanced Solvent Extraction method (ASE). Extraction temperature and pressure were kept at 100 C, respectively 150 C, and 20,7 MPa. After the heating phase (5 min) static extractions were performed with mixtures (v:v, 1:3) of methanol with toluene, respectively trichloromethane, for further 5 min. Extract yields were the same or on a higher level compared to those from classical soxhlet extractions (3 days) using the same solvents at 60 C. Comparing the results from ASE with those from supercritical fluid extraction (SFE) the extract yields were similar. Increasing the temperature in ASE releases more soluble organic matter from geological samples, because compounds with higher molecular weight and especially more polar substances were solubilized. But also an enhanced extraction efficiency resulted for aliphatic and aromatic hydrocarbons which are used as biomarkers in Organic Geochemistry. Application of thermochemolysis with tetraethylammonium hydroxide (TEAH) using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) on the extraction residues shows clearly that at higher extraction temperatures minor amounts of free fatty acids or their methyl esters (original or produced by ASE) were trapped inside the pore systems of the oil shale or the bituminous coal. ASE offers a rapid and very efficient extraction method for geological samples reducing analysis time and costs for solvents. (orig.)

  3. Solvent extraction: the coordination chemistry behind extractive metallurgy.

    Science.gov (United States)

    Wilson, A Matthew; Bailey, Phillip J; Tasker, Peter A; Turkington, Jennifer R; Grant, Richard A; Love, Jason B

    2014-01-07

    The modes of action of the commercial solvent extractants used in extractive hydrometallurgy are classified according to whether the recovery process involves the transport of metal cations, M(n+), metalate anions, MXx(n-), or metal salts, MXx into a water-immiscible solvent. Well-established principles of coordination chemistry provide an explanation for the remarkable strengths and selectivities shown by most of these extractants. Reagents which achieve high selectivity when transporting metal cations or metal salts into a water-immiscible solvent usually operate in the inner coordination sphere of the metal and provide donor atom types or dispositions which favour the formation of particularly stable neutral complexes that have high solubility in the hydrocarbons commonly used in recovery processes. In the extraction of metalates, the structures of the neutral assemblies formed in the water-immiscible phase are usually not well defined and the cationic reagents can be assumed to operate in the outer coordination spheres. The formation of secondary bonds in the outer sphere using, for example, electrostatic or H-bonding interactions are favoured by the low polarity of the water-immiscible solvents.

  4. Physicochemical and catalytic properties of Au nanorods micro-assembled in solvents of varying dipole moment and refractive index

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Rupinder; Pal, Bonamali, E-mail: bpal@thapar.edu

    2015-02-15

    Highlights: • Physicochemical activities of Au nanorods in water largely differ from organic solvents. • Au nanorods agglomeration increased with dipole moments of different polar solvents. • Refractive indexes of Au nanorods dispersion in various polar solvents are enhanced. • Electrokinetics significantly altered depending on agglomerated size of Au nanorods. • Catalysis or co-catalysis activity is varied as per the extent of Au nanorods coagulation. - Abstract: This paper deals with the impact of dipole moment (1.66–3.96 D) and refractive index (1.333–1.422) of the dispersion solvent on the plasmon absorption, surface charge, zeta potential, and adsorption properties of Au nanorods (AuNRs). AuNRs (length ≈ 53 nm and width ≈ 20 nm) undergo agglomeration (size 50–180 nm) with increase in the dipole moment of solvent (iPrOH < MeOH < DMF < DMSO). Whereas, no such coagulation occurs in H{sub 2}O and CCl{sub 4} suspension as confirmed by DLS and TEM size distribution. The electrostatic interaction of AuNRs with its surface adsorbed solvent dipoles leads to alteration of the their ionic state, absolute electronic charge and zeta potential (+49.79 mV in H{sub 2}O, +8.99 mV in DMF and −4.65 mV in MeOH dispersion) to a greater extent. This interaction distinctly modifies the adsorption behavior of polar molecules like p-nitrophenol and salicylic acid on AuNRs surface, as evidenced by the measured changes in their electro-kinetic parameters. As a result, we observe a substantial difference in catalytic and co-catalytic activities of AuNRs dispersed in various solvents as mentioned above because the catalytic properties of AuNRs are strongly dependent on the type of solvent in which they are dispersed.

  5. Solvent Effects in Asymmetric Hetero Diels-Alder and Ene Reactions

    DEFF Research Database (Denmark)

    Johannsen, Mogens; Jørgensen, Karl Anker

    1996-01-01

    The use of polar solvents such as nitromethane or 2-nitropropane leads to a significant improvement of the catalytic properties of a cationic copper-Lewis acid in the hetero Diels-Alder reaction of alkyl glyoxylates with dienes; The scope of a newly developed copper(II)-bisoxazoline catalyst...... for the hetero Diels-Alder reaction is demonstrated by the reaction of different dienes with alkyl glyoxylates in nitroalkane solvents with the formation of the hetero Diels-Alder adduct in high enantiomeric excess as the major product. The synthetic application of the reaction is exemplified by an improved...

  6. Electronic excitations in a dielectric continuum solvent with quantum Monte Carlo: Acrolein in water

    Energy Technology Data Exchange (ETDEWEB)

    Floris, Franca Maria, E-mail: floris@dcci.unipi.it; Amovilli, Claudio [Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Risorgimento 35, 56126 Pisa (Italy); Filippi, Claudia [MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2014-01-21

    We investigate here the vertical n → π{sup *} and π → π{sup *} transitions of s-trans-acrolein in aqueous solution by means of a polarizable continuum model (PCM) we have developed for the treatment of the solute at the quantum Monte Carlo (QMC) level of the theory. We employ the QMC approach which allows us to work with highly correlated electronic wave functions for both the solute ground and excited states and, to study the vertical transitions in the solvent, adopt the commonly used scheme of considering fast and slow dielectric polarization. To perform calculations in a non-equilibrium solvation regime for the solute excited state, we add a correction to the global dielectric polarization charge density, obtained self consistently with the solute ground-state wave function by assuming a linear-response scheme. For the solvent polarization in the field of the solute in the ground state, we use the static dielectric constant while, for the electronic dielectric polarization, we employ the solvent refractive index evaluated at the same frequency of the photon absorbed by the solute for the transition. This choice is shown to be better than adopting the most commonly used value of refractive index measured in the region of visible radiation. Our QMC calculations show that, for standard cavities, the solvatochromic shifts obtained with the PCM are underestimated, even though of the correct sign, for both transitions of acrolein in water. Only by reducing the size of the cavity to values where more than one electron is escaped to the solvent region, we regain the experimental shift for the n → π{sup *} case and also improve considerably the shift for the π → π{sup *} transition.

  7. Synthesis of SERS active Au nanowires in different noncoordinating solvents

    Energy Technology Data Exchange (ETDEWEB)

    Hou Xiaomiao; Zhang Xiaoling, E-mail: zhangxl@bit.edu.cn [Key Laboratory of Cluster Science of Ministry of Education, Beijing Institute of Technology, Department of Chemistry, School of Science (China); Fang Yan, E-mail: fangyan@mail.cnu.edu.cn [Beijing Key Laboratory for Nano-Photonics and Nano-Structure (NPNS), Capital Normal University (China); Chen Shutang; Li Na; Zhou Qi [Key Laboratory of Cluster Science of Ministry of Education, Beijing Institute of Technology, Department of Chemistry, School of Science (China)

    2011-06-15

    Au nanowires with length up to micrometers were synthesized through a simple and one-pot solution growth method. HAuCl{sub 4} was reduced in a micellar structure formed by 1-octadecylamine and oleic acid in hexane, heptane, toluene and chloroform, respectively. As the non-polarity of noncoordinating solvents can affect the nucleation and growth rates of Au nanostructures, Au nanowires with different diameters could be obtained by changing the noncoordinating solvents in the synthetic process. The influences of the solvents on the morphology of Au nanowires were systematically studied. When using hexane as reaction solvent, the product turned to be high portion of Au nanowires with more uniform size than the others. Furthermore, surface-enhanced Raman scattering (SERS) spectrum of 2-thionaphthol was obtained on the Au nanowire-modified substrate, indicating that the as-synthesized Au nanowires have potential for highly sensitive optical detection application.

  8. Thin-film composite crosslinked polythiosemicarbazide membranes for organic solvent nanofiltration (OSN)

    KAUST Repository

    Aburabie, Jamaliah

    2015-01-01

    In this work we report a new class of solvent stable thin-film composite (TFC) membrane fabricated on crosslinked polythiosemicarbazide (PTSC) as substrate that exhibits superior stability compared with other solvent stable polymeric membranes reported up to now. Integrally skinned asymmetric PTSC membranes were prepared by the phase inversion process and crosslinked with an aromatic bifunctional crosslinker to improve the solvent stability. TFC membranes were obtained via interfacial polymerization using trimesoyl chloride (TMC) and diaminopiperazine (DAP) monomers. The membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and contact angle measurement.The membranes exhibited high fluxes toward solvents like tetrahydrofuran (THF), dimethylformamide (DMF) and dimethylsulfoxide (DMSO) ranging around 20L/m2 h at 5bar with a molecular weight cut off (MWCO) of around 1000g/mol. The PTSC-based thin-film composite membranes are very stable toward polar aprotic solvents and they have potential applications in the petrochemical and pharmaceutical industry.

  9. Crosslinked copolyazoles with a zwitterionic structure for organic solvent resistant membranes

    KAUST Repository

    Chisca, Stefan

    2015-01-01

    The preparation of crosslinked membranes with a zwitterionic structure based on a facile reaction between a newly synthesized copolyazole with free OH groups and (3-glycidyloxypropyl)trimethoxysilane (GPTMS) is reported. The new OH-functionalized copolyazole is soluble in common organic solvents, such as tetrahydrofuran (THF), dimethylsulfoxide (DMSO), N,N′-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP) and can be easily processed by phase inversion. After crosslinking with GPTMS, the membranes acquire high solvent resistance. We show the membrane performance and the influence of the crosslinking reaction conditions on the thermal stability, surface polarity, pore morphology, and solvent resistance. By using UV-spectroscopy we monitored the solvent resistance of the membranes in four aggressive solvents (THF, DMSO, DMF and NMP) for 30 days. After this time, only minor changes (less than 2%) were detected for membranes subjected to a crosslinking reaction for 6 hours or longer. Our data suggest that the novel crosslinked membranes can be used for industrial applications in wide harsh environments in the presence of organic solvents.

  10. A comparative study on the effect of solvent on nucleophilic fluorination with [18F]fluoride. Protic solvents as co-solvents in SN2 and SNAr reactions

    International Nuclear Information System (INIS)

    Koivula, T.; Simecek, J.; Jalomaeki, J.; Helariutta, K.; Airaksinen, A.J.

    2011-01-01

    The effect of solvent on nucleophilic substitution with cyclotron-produced [ 18 F]fluoride was studied in polar aprotic (CH 3 CN and DMF) and protic solvent (t-BuOH and t-amyl alcohol) mixtures (CH 3 CN/co-solvent, 2:8) in a series of model compounds, 4-(R 1 -methyl)benzyl R 2 -benzoates, using a K2.2.2/[ 18 F]KF phase transfer system (R 1 = -Cl, -OMs or -OH; R 2 = -Cl, -I or -NO 2 ). 18 F-fluorination of compounds 1-3, with chloride or mesylate as a leaving group in the benzylic position (R 1 ), afforded the desired 4-([ 18 F]fluoromethyl)benzyl analogues in all solvents during 15 min reaction time. The highest radiochemical yields (RCY) in all the studied reaction temperatures (80, 120 and 160 C) were achieved in CH 3 CN. Radiochemical yields in protic solvents were comparable to RCY in CH 3 CN only with the sulfonate ester 3 as a starting material. 18 F-Fluorination of the benzylic halides 1 and 2 was not promoted in the same extent; in addition, labelled side-products were detected at higher reaction temperatures. Radiofluorination in tert-alcohols was also studied using [ 18 F]CsF with and without added phase transfer catalyst, resulting in both conditions lower RCY when compared to K2.2.2/[ 18 F]KF system. Protic solvents were not able to promote aromatic 18 F-fluorination. 18 F-Fluorination of compound 5, having para-activated nitro group in the aromatic position (R 2 ), failed in tert-alcohols even at the highest temperature, but it was labelled successfully in DMF and to some extent in CH 3 CN. (orig.)

  11. Synthesis and investigation of solvent effects on the ultraviolet absorption spectra of 5-substituted-4-methyl-3-cyano-6-hydroxy-2-pyridones

    Directory of Open Access Journals (Sweden)

    NATASA V. VALENTIC

    2001-08-01

    Full Text Available A number of 5-substituted-4-methyl-3-cyano-6-hydroxy-2-pyridones from cyanoacetamide and the corresponding alkyl ethyl acetoacetates were synthesized according to modified literature procedures. The alkyl ethyl acetoacetates were obtained by the reaction of C-alkylation of ethyl acetoacetate. An investigation of the reaction conditions for the synthesis of 4-methyl-3-cyano-6-hydroxy-2-pyridone from cyanoacetamide and ethyl acetoacetate in eight different solvents was also performed. The ultraviolet absorption spectra of synthesized pyridones were measured in nine different solvents in the range 200–400 nm. The effects of solvent polarity and hydrogen bonding on the absorption spectra are interpreted by means of linear solvation energy relationships using a general equation of the form n = n0 + sp* + aa + bb, where p* is a measure of the solvent polarity, a is the scale of the solvent hydrogen bond donor acidities and b is the scale of the solvent hydrogen bond acceptor basicities.

  12. Nonadiabatic dynamics of electron transfer in solution: Explicit and implicit solvent treatments that include multiple relaxation time scales

    International Nuclear Information System (INIS)

    Schwerdtfeger, Christine A.; Soudackov, Alexander V.; Hammes-Schiffer, Sharon

    2014-01-01

    The development of efficient theoretical methods for describing electron transfer (ET) reactions in condensed phases is important for a variety of chemical and biological applications. Previously, dynamical dielectric continuum theory was used to derive Langevin equations for a single collective solvent coordinate describing ET in a polar solvent. In this theory, the parameters are directly related to the physical properties of the system and can be determined from experimental data or explicit molecular dynamics simulations. Herein, we combine these Langevin equations with surface hopping nonadiabatic dynamics methods to calculate the rate constants for thermal ET reactions in polar solvents for a wide range of electronic couplings and reaction free energies. Comparison of explicit and implicit solvent calculations illustrates that the mapping from explicit to implicit solvent models is valid even for solvents exhibiting complex relaxation behavior with multiple relaxation time scales and a short-time inertial response. The rate constants calculated for implicit solvent models with a single solvent relaxation time scale corresponding to water, acetonitrile, and methanol agree well with analytical theories in the Golden rule and solvent-controlled regimes, as well as in the intermediate regime. The implicit solvent models with two relaxation time scales are in qualitative agreement with the analytical theories but quantitatively overestimate the rate constants compared to these theories. Analysis of these simulations elucidates the importance of multiple relaxation time scales and the inertial component of the solvent response, as well as potential shortcomings of the analytical theories based on single time scale solvent relaxation models. This implicit solvent approach will enable the simulation of a wide range of ET reactions via the stochastic dynamics of a single collective solvent coordinate with parameters that are relevant to experimentally accessible

  13. Influence of Solvent Polarity and DNA-Binding on Spectral Properties of Quaternary Benzo[c]phenanthridine Alkaloids.

    Directory of Open Access Journals (Sweden)

    Michal Rájecký

    Full Text Available Quaternary benzo[c]phenanthridine alkaloids are secondary metabolites of the plant families Papaveraceae, Rutaceae, and Ranunculaceae with anti-inflammatory, antifungal, antimicrobial and anticancer activities. Their spectral changes induced by the environment could be used to understand their interaction with biomolecules as well as for analytical purposes. Spectral shifts, quantum yield and changes in lifetime are presented for the free form of alkaloids in solvents of different polarity and for alkaloids bound to DNA. Quantum yields range from 0.098 to 0.345 for the alkanolamine form and are below 0.033 for the iminium form. Rise of fluorescence lifetimes (from 2-5 ns to 3-10 ns and fluorescence intensity are observed after binding of the iminium form to the DNA for most studied alkaloids. The alkanolamine form does not bind to DNA. Acid-base equilibrium constant of macarpine is determined to be 8.2-8.3. Macarpine is found to have the highest increase of fluorescence upon DNA binding, even under unfavourable pH conditions. This is probably a result of its unique methoxy substitution at C12 a characteristic not shared with other studied alkaloids. Association constant for macarpine-DNA interaction is 700000 M(-1.

  14. Polar aprotic solvent-water mixture as the medium for catalytic production of hydroxymethylfurfural (HMF) from bread waste.

    Science.gov (United States)

    Yu, Iris K M; Tsang, Daniel C W; Chen, Season S; Wang, Lei; Hunt, Andrew J; Sherwood, James; De Oliveira Vigier, Karine; Jérôme, François; Ok, Yong Sik; Poon, Chi Sun

    2017-12-01

    Valorisation of bread waste for hydroxymethylfurfural (HMF) synthesis was examined in dimethyl sulfoxide (DMSO)-, tetrahydrofuran (THF)-, acetonitrile (ACN)-, and acetone-water (1:1v/v), under heating at 140°C with SnCl 4 as the catalyst. The overall rate of the process was the fastest in ACN/H 2 O and acetone/H 2 O, followed by DMSO/H 2 O and THF/H 2 O due to the rate-limiting glucose isomerisation. However, the formation of levulinic acid (via rehydration) and humins (via polymerisation) was more significant in ACN/H 2 O and acetone/H 2 O. The constant HMF maxima (26-27mol%) in ACN/H 2 O, acetone/H 2 O, and DMSO/H 2 O indicated that the rates of desirable reactions (starch hydrolysis, glucose isomerisation, and fructose dehydration) relative to undesirable pathways (HMF rehydration and polymerisation) were comparable among these mediums. They also demonstrated higher selectivity towards HMF production over the side reactions than THF/H 2 O. This study differentiated the effects of polar aprotic solvent-water mediums on simultaneous pathways during biomass conversion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Exciplex fluorescence emission from simple organic intramolecular constructs in non-polar and highly polar media as model systems for DNA-assembled exciplex detectors.

    Science.gov (United States)

    Bichenkova, Elena V; Sardarian, Ali R; Wilton, Amanda N; Bonnet, Pascal; Bryce, Richard A; Douglas, Kenneth T

    2006-01-21

    Organic intramolecular exciplexes, N-(4-dimethylaminobenzyl)-N-(1-pyrenemethyl)amine (1) and N'-4-dimethylaminonaphthyl-N-(1-pyrenemethyl)amine (2), were used as model systems to reveal major factors affecting their exciplex fluorescence, and thus lay the basis for developing emissive target-assembled exciplexes for DNA-mounted systems in solution. These models with an aromatic pyrenyl hydrocarbon moiety as an electron acceptor appropriately connected to an aromatic dimethylamino electron donor component (N,N-dimethylaminophenyl or N,N-dimethylaminonaphthyl) showed strong intramolecular exciplex emission in both non-polar and highly polar solvents. The effect of dielectric constant on the maximum wavelength for exciplex emission was studied, and emission was observed for 1 and 2 over the full range of solvent from non-polar hydrocarbons up to N-methylformamide with a dielectric constant of 182. Quantum yields were determined for these intramolecular exciplexes in a range of solvents relative to that for Hoechst 33,258. Conformational analysis of 1 was performed both computationally and via qualitative 2D NMR using (1)H-NOESY experiments. The results obtained indicated the contribution of pre-folded conformation(s) to the ground state of 1 conducive to exciplex emission. This research provides the initial background for design of self-assembled, DNA-mounted exciplexes and underpins further development of exciplex-based hybridisation bioassays.

  16. Reduction of coating induced polarization aberrations by controlling the polarization state variation

    International Nuclear Information System (INIS)

    Li, Yanghui; Shen, Weidong; Zheng, Zhenrong; Zhang, Yueguang; Liu, Xu; Hao, Xiang

    2011-01-01

    The mechanism of coating induced polarization state variation is analysed by the Jones matrix. Pauli spin matrices are used to establish the relationship between coating induced polarization state variation and polarization aberrations. To reduce coating induced polarization aberrations, we propose that δ = 0 and T s = T p at arbitrary incident angle should be appended as two additional optimization goals of optical coating design when the requirements of transmittance are met. Two typical anti-reflection (AR) coatings are designed and the polarization state variation induced by them is simulated. The MTF (modulation transfer function) calculated by polarization ray tracing is applied to evaluate the polarization aberrations of the practical lithography objective system with the two AR coatings. All the obtained results show that the coating induced polarization aberrations can be reduced by optimizing the angle dependent properties of the optical coating without additional optical elements

  17. Depleted depletion drives polymer swelling in poor solvent mixtures.

    Science.gov (United States)

    Mukherji, Debashish; Marques, Carlos M; Stuehn, Torsten; Kremer, Kurt

    2017-11-09

    Establishing a link between macromolecular conformation and microscopic interaction is a key to understand properties of polymer solutions and for designing technologically relevant "smart" polymers. Here, polymer solvation in solvent mixtures strike as paradoxical phenomena. For example, when adding polymers to a solvent, such that all particle interactions are repulsive, polymer chains can collapse due to increased monomer-solvent repulsion. This depletion induced monomer-monomer attraction is well known from colloidal stability. A typical example is poly(methyl methacrylate) (PMMA) in water or small alcohols. While polymer collapse in a single poor solvent is well understood, the observed polymer swelling in mixtures of two repulsive solvents is surprising. By combining simulations and theoretical concepts known from polymer physics and colloidal science, we unveil the microscopic, generic origin of this collapse-swelling-collapse behavior. We show that this phenomenon naturally emerges at constant pressure when an appropriate balance of entropically driven depletion interactions is achieved.

  18. Theoretical Study on the Extraction of Alkaline Earth Salts by 18-Crown-6: Roles of Counterions, Solvent Types and Extraction Temperatures

    Directory of Open Access Journals (Sweden)

    Saprizal Hadisaputra

    2014-07-01

    Full Text Available The roles of counterions, solvent types and extraction temperatures on the selectivity of 18-crown-6 (L toward alkaline earth salts MX2 (M = Ca, Sr, Ba; X = Cl-, NO3- have been studied by density functional method at B3LYP level of theory in gas and solvent phase. In gas phase, the chloride anion Cl- is the preference counterion than nitrate anion NO3-. This result is confirmed by the interaction energies, the second order interaction energies, charge transfers, energy difference between HOMO-LUMO and electrostatic potential maps. The presence of solvent reversed the gas phase trend. It is found that NO3- is the preference counterion in solvent phase. The calculated free energies demonstrate that the solvent types strongly change the strength of the complex formation. The free energies are exothermic in polar solvent while for the non polar solvent the free energies are endothermic. As the temperature changes the free energies also vary where the higher the temperatures the lower the free energy values. The calculated free energies are correlated well with the experimental stability constants. This theoretical study would have a strong contribution in planning the experimental conditions in terms of the preference counterions, solvent types and optimum extraction temperatures.

  19. Influence of electrolyte ion-solvent interactions on the performances of supercapacitors porous carbon electrodes

    Science.gov (United States)

    Decaux, C.; Matei Ghimbeu, C.; Dahbi, M.; Anouti, M.; Lemordant, D.; Béguin, F.; Vix-Guterl, C.; Raymundo-Piñero, E.

    2014-10-01

    The development of advanced and safe electrochemical supercapacitors or hybrid supercapacitors combining a battery electrode material such as graphite and a porous carbon electrode implies the use of new electrolytes containing a tetra-alkylammonium or lithium salt dissolved preferentially in a safe and environmentally friendly solvent such as alkylcarbonates. In those systems, the carbon porosity of the activated carbon electrode controls the electrochemical behavior of the whole device. In this work, it is demonstrated that electrolytes containing highly polarizing ions such as Li+ dissolved in polar solvents such as alkylcarbonates do not completely loss their solvation shell at the opposite of what is observed for poorly solvated cations like TEABF4. As a consequence, the optimal carbon pore size for obtaining the largest energy density, while keeping a high power density, is wider when strongly solvated cations, like Li+ are used than for conventional organic electrolytes using acetonitrile as solvent and TEA+ as salt cations. TEA+ cations are easily desolvated and hence are able to penetrate in small pores matching the dimensions of bare ions. The dissimilarity of behavior of alkylcarbonates and acetonitrile based electrolytes highlights the importance of ion-solvent interactions when searching the optimal porous texture for the electrode material.

  20. Ultrasonication-Assisted Solvent Extraction of Quercetin Glycosides from ‘Idared’ Apple Peels

    Directory of Open Access Journals (Sweden)

    Gwendolyn M. Huber

    2011-11-01

    Full Text Available Quercetin and quercetin glycosides are physiologically active flavonol molecules that have been attributed numerous health benefits. Recovery of such molecules from plant matrices depends on a variety of factors including polarity of the extraction solvent. Among the solvents of a wide range of dielectric constants, methanol recovered the most quercetin and its glycosides from dehydrated ‘Idared’ apple peels. When ultra-sonication was employed to facilitate the extraction, exposure of 15 min of ultrasound wavelengths of dehydrated apple peel powder in 80% to 100% (v/v methanol in 1:50 (w:v solid to solvent ratio provided the optimum extraction conditions for quercetin and its glycosides. Acidification of extraction solvent with 0.1% (v/v or higher concentrations of HCl led to hydrolysis of naturally occurring quercetin glycosides into the aglycone as an extraction artifact.

  1. Effect of Solvents on the Product Distribution and Reaction Rate of a Buchwald-Hartwig Amination Reaction

    DEFF Research Database (Denmark)

    Christensen, H.; Kiil, Søren; Dam-Johansen, Kim

    2006-01-01

    The Buchwald-Hartwig amination reaction between p-bromotoluene and piperazine in the presence of the homogeneous catalytic system Pd(dba)(2)/(+/-)-BINAP and the base NaO-t-Bu was investigated in two different classes of solvents: aprotic, nonpolar and aprotic, polar. The reaction was carried out...... solvent for the Buchwald-Hartwig amination reaction under the conditions applied was m-xylene....

  2. Solvent, isotope, and magnetic field effects in the geminate recombination of radical ion pairs

    International Nuclear Information System (INIS)

    Werner, H.; Staerk, H.; Weller, A.

    1978-01-01

    The magnetic field dependence of the geminate recombination triplet yield of radical ion pairs generated via photoinduced electron transfer in polar solvents is investigated for the systems pyrene/N,N-dimethylaniline (Py/DMA), pyrene/3,5-dimethoxy-N,N-dimethylaniline (Py/DMDMA), and the perdeuterated system Py-d 10 /DMA-d 11 . The magnetic field dependence characterized through its B/sub 1/2/ value is found to be dependent on the sum of the hyperfine coupling constants in the radical pair in agreement with previous theoretical predictions. A drastic reduction of the B/sub 1/2/ value is observed with the perdeuterated system. By means of measurements of the radical ion and triplet absorption signals with nanosecond time resolution, the influence of the solvent on the geminate singlet and triplet recombination yields is investigated. Complementary measurements of exciplex lifetimes and quantum yields are carried out in a series of solvents with different polarities in order to determine the rate constants of fluorescence emission and intersystem crossing in the exciplexes

  3. Free energy functionals for polarization fluctuations: Pekar factor revisited.

    Science.gov (United States)

    Dinpajooh, Mohammadhasan; Newton, Marshall D; Matyushov, Dmitry V

    2017-02-14

    The separation of slow nuclear and fast electronic polarization in problems related to electron mobility in polarizable media was considered by Pekar 70 years ago. Within dielectric continuum models, this separation leads to the Pekar factor in the free energy of solvation by the nuclear degrees of freedom. The main qualitative prediction of Pekar's perspective is a significant, by about a factor of two, drop of the nuclear solvation free energy compared to the total (electronic plus nuclear) free energy of solvation. The Pekar factor enters the solvent reorganization energy of electron transfer reactions and is a significant mechanistic parameter accounting for the solvent effect on electron transfer. Here, we study the separation of the fast and slow polarization modes in polar molecular liquids (polarizable dipolar liquids and polarizable water force fields) without relying on the continuum approximation. We derive the nonlocal free energy functional and use atomistic numerical simulations to obtain nonlocal, reciprocal space electronic and nuclear susceptibilities. A consistent transition to the continuum limit is introduced by extrapolating the results of finite-size numerical simulation to zero wavevector. The continuum nuclear susceptibility extracted from the simulations is numerically close to the Pekar factor. However, we derive a new functionality involving the static and high-frequency dielectric constants. The main distinction of our approach from the traditional theories is found in the solvation free energy due to the nuclear polarization: the anticipated significant drop of its magnitude with increasing liquid polarizability does not occur. The reorganization energy of electron transfer is either nearly constant with increasing the solvent polarizability and the corresponding high-frequency dielectric constant (polarizable dipolar liquids) or actually noticeably increases (polarizable force fields of water).

  4. Free energy functionals for polarization fluctuations: Pekar factor revisited

    International Nuclear Information System (INIS)

    Dinpajooh, Mohammadhasan; Newton, Marshall D.; Matyushov, Dmitry V.

    2017-01-01

    The separation of slow nuclear and fast electronic polarization in problems related to electron mobility in polarizable media was considered by Pekar 70 years ago. This separation leads to the Pekar factor in the free energy of solvation by the nuclear degrees of freedom, within dielectric continuum models. The main qualitative prediction of Pekar’s perspective is a significant, by about a factor of two, drop of the nuclear solvation free energy compared to the total (electronic plus nuclear) free energy of solvation. The Pekar factor enters the solvent reorganization energy of electron transfer reactions and is a significant mechanistic parameter accounting for the solvent effect on electron transfer. We study the separation of the fast and slow polarization modes in polar molecular liquids (polarizable dipolar liquids and polarizable water force fields) without relying on the continuum approximation. We derive the nonlocal free energy functional and use atomistic numerical simulations to obtain nonlocal, reciprocal space electronic and nuclear susceptibilities. A consistent transition to the continuum limit is introduced by extrapolating the results of finite-size numerical simulation to zero wavevector. The continuum nuclear susceptibility extracted from the simulations is numerically close to the Pekar factor. But, we derive a new functionality involving the static and high-frequency dielectric constants. The main distinction of our approach from the traditional theories is found in the solvation free energy due to the nuclear polarization: the anticipated significant drop of its magnitude with increasing liquid polarizability does not occur. The reorganization energy of electron transfer is either nearly constant with increasing the solvent polarizability and the corresponding high-frequency dielectric constant (polarizable dipolar liquids) or actually noticeably increases (polarizable force fields of water).

  5. Opportunities for Bio-Based Solvents Created as Petrochemical and Fuel Products Transition towards Renewable Resources.

    Science.gov (United States)

    Clark, James H; Farmer, Thomas J; Hunt, Andrew J; Sherwood, James

    2015-07-28

    The global bio-based chemical market is growing in size and importance. Bio-based solvents such as glycerol and 2-methyltetrahydrofuran are often discussed as important introductions to the conventional repertoire of solvents. However adoption of new innovations by industry is typically slow. Therefore it might be anticipated that neoteric solvent systems (e.g., ionic liquids) will remain niche, while renewable routes to historically established solvents will continue to grow in importance. This review discusses bio-based solvents from the perspective of their production, identifying suitable feedstocks, platform molecules, and relevant product streams for the sustainable manufacturing of conventional solvents.

  6. Opportunities for Bio-Based Solvents Created as Petrochemical and Fuel Products Transition towards Renewable Resources

    Science.gov (United States)

    Clark, James H.; Farmer, Thomas J.; Hunt, Andrew J.; Sherwood, James

    2015-01-01

    The global bio-based chemical market is growing in size and importance. Bio-based solvents such as glycerol and 2-methyltetrahydrofuran are often discussed as important introductions to the conventional repertoire of solvents. However adoption of new innovations by industry is typically slow. Therefore it might be anticipated that neoteric solvent systems (e.g., ionic liquids) will remain niche, while renewable routes to historically established solvents will continue to grow in importance. This review discusses bio-based solvents from the perspective of their production, identifying suitable feedstocks, platform molecules, and relevant product streams for the sustainable manufacturing of conventional solvents. PMID:26225963

  7. Continuum model of non-equilibrium solvation and solvent effect on ultra-fast processes

    International Nuclear Information System (INIS)

    Li Xiangyuan; Fu Kexiang; Zhu Quan

    2006-01-01

    In the past 50 years, non-equilibrium solvation theory for ultra-fast processes such as electron transfer and light absorption/emission has attracted particular interest. A great deal of research efforts was made in this area and various models which give reasonable qualitative descriptions for such as solvent reorganization energy in electron transfer and spectral shift in solution, were developed within the framework of continuous medium theory. In a series of publications by the authors, we clarified that the expression of the non-equilibrium electrostatic free energy that is at the dominant position of non-equilibrium solvation and serves as the basis of various models, however, was incorrectly formulated. In this work, the authors argue that reversible charging work integration was inappropriately applied in the past to an irreversible path linking the equilibrium or the non-equilibrium state. Because the step from the equilibrium state to the nonequilibrium state is factually thermodynamically irreversible, the conventional expression for non-equilibrium free energy that was deduced in different ways is unreasonable. Here the authors derive the non-equilibrium free energy to a quite different form according to Jackson integral formula. Such a difference throws doubts to the models including the famous Marcus two-sphere model for solvent reorganization energy of electron transfer and the Lippert-Mataga equation for spectral shift. By introducing the concept of 'spring energy' arising from medium polarizations, the energy constitution of the non-equilibrium state is highlighted. For a solute-solvent system, the authors separate the total electrostatic energy into different components: the self-energies of solute charge and polarized charge, the interaction energy between them and the 'spring energy' of the solvent polarization. With detailed reasoning and derivation, our formula for non-equilibrium free energy can be reached through different ways. Based on the

  8. Enzymatic synthesis of 6-O-glucosyl-poly(3-hydroxyalkanoate) in organic solvents and their binary mixture.

    Science.gov (United States)

    Gumel, A M; Annuar, M S M; Heidelberg, T

    2013-04-01

    The effects of organic solvents and their binary mixture in the glucose functionalization of bacterial poly-3-hydroxyalkanoates catalyzed by Lecitase™ Ultra were studied. Equal volume binary mixture of DMSO and chloroform with moderate polarity was more effective for the enzyme catalyzed synthesis of the carbohydrate polymer at ≈38.2 (±0.8)% reactant conversion as compared to the mono-phasic and other binary solvents studied. The apparent reaction rate constant as a function of medium water activity (aw) was observed to increase with increasing solvent polarity, with optimum aw of 0.2, 0.4 and 0.7 (±0.1) observed in hydrophilic DMSO, binary mixture DMSO:isooctane and hydrophobic isooctane, respectively. Molecular sieve loading between 13 to 15gL(-1) (±0.2) and reaction temperature between 40 to 50°C were found optimal. Functionalized PHA polymer showed potential characteristics and biodegradability. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Solvent influence on the photophysical properties of 4-(2-Oxo-2H-benzo[h]chromen-4-ylmethoxy)-benzaldehyde

    Science.gov (United States)

    Pramod, A. G.; Renuka, C. G.; Shivashankar, K.; Boregowda, P.; Nadaf, Y. F.

    2018-05-01

    Steady-state absorption and the fluorescence properties of the synthesized Benzofuran derivatives were studied. Absorption and fluorescence spectra of 4-(2-Oxo-2H-benzo[h]chromen-4-ylm ethoxy)-benzaldehyde (4-OBCM) have been recorded at room temperature in extensive variety of solvents of various polarities. 4-OBCM Fluorescence band maxima of the solvents are small amount spectral shifted to hypsochromic when the solvent polarity will increase, compared to absorption band under the identical circumstance. This suggests an increase in dipole moment of excited state compared to ground state. The ground-state dipole moment of 4-OBCM was found from quantum mechanical methods and the excited state dipole moment of 4-OBCM was evaluated from Lippert-Mataga Bakhshiev's, Kawski-Chamma-Viallet's and Reichardt conditions by methods for solvatochromic shift. Kamlet-Taft coefficients which affect this absorption profiles.

  10. Vitamin E Circular Dichroism Studies: Insights into Conformational Changes Induced by the Solvent’s Polarity

    Directory of Open Access Journals (Sweden)

    Drew Marquardt

    2016-12-01

    Full Text Available We used circular dichroism (CD to study differences in CD spectra between α-, δ-, and methylated-α-tocopherol in solvents with different polarities. CD spectra of the different tocopherol structures differ from each other in intensity and peak locations, which can be attributed to chromanol substitution and the ability to form hydrogen bonds. In addition, each structure was examined in different polarity solvents using the Reichardt index—a measure of the solvent’s ionizing ability, and a direct measurement of solvent–solute interactions. Differences across solvents indicate that hydrogen bonding is a key contributor to CD spectra at 200 nm. These results are a first step in examining the hydrogen bonding abilities of vitamin E in a lipid bilayer.

  11. Thermodynamically based solvent design for enzymatic saccharide acylation with hydroxycinnamic acids in non-conventional media

    DEFF Research Database (Denmark)

    Zeuner, Birgitte; Kontogeorgis, Georgios; Riisager, Anders

    2012-01-01

    as well as other enzymatic hydroxycinnamate acylations in ionic liquid systems. The choice of solvent system is highly decisive for enzyme stability, selectivity, and reaction yields in these synthesis reactions. To increase the understanding of the reaction environment and to facilitate solvent screening......-free microemulsions of a hydrocarbon, a polar alcohol, and water are interesting solvent systems because they accommodate different substrate and product solubilities and maintain enzyme stability. Ionic liquids may provide advantages as solvents in terms of increased substrate and product solubility, higher...... of their amphiphilicity and antioxidative potential. Synthetic reactions using mono- or disaccharides as one of the substrates may moreover direct new routes for biomass upgrading in the biorefinery. The paper reviews the available data for enzymatic hydroxycinnamate saccharide ester synthesis in organic solvent systems...

  12. Novel Paradigm Supercapacitors V: Significance of Organic Polar Solvents and Salt Identities

    Science.gov (United States)

    2017-06-01

    146 E. DISCUSSION OF VARIABLES ..........................................................146 1. Viscosity and Density...146 Table 77. Kinematic Viscosity and Density of Water and Tested Solvents...surface area per unit mass, or unit volume [22]. Examples of this material include carbon, conductive clays , some metal and oxides and graphene. These

  13. Modelos contínuos do solvente: fundamentos Continuum solvation models: fundamentals

    Directory of Open Access Journals (Sweden)

    Josefredo R. Pliego Jr

    2006-06-01

    Full Text Available Continuum solvation models are nowadays widely used in the modeling of solvent effects and the range of applications goes from the calculation of partition coefficients to chemical reactions in solution. The present work presents a detailed explanation of the physical foundations of continuum models. We discuss the polarization of a dielectric and its representation through the volume and surface polarization charges. The Poisson equation for a dielectric was obtained and we have also derived and discuss the apparent surface charge method and its application for free energy of solvation calculations.

  14. 40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... Large Appliances Pt. 63, Subpt. NNNN, Table 3 Table 3 to Subpart NNNN of Part 63—Default Organic HAP.../solvent blend CAS. No. Average organic HAP mass fraction Typical organic HAP, percent by mass 1. Toluene...

  15. Molecular and ionic hydrogen bond formation in fluorous solvents.

    Science.gov (United States)

    O'Neal, Kristi L; Weber, Stephen G

    2009-01-08

    There are only a few studies of noncovalent association in fluorous solvents and even fewer that are quantitative. A full understanding, particularly of stoichiometry and binding strength of noncovalent interactions in fluorous solvents could be very useful in improved molecular-receptor-based extractions, advancements in sensor technologies, crystal engineering, and supramolecular chemistry. This work investigates hydrogen bonding between heterocyclic bases and a perfluoropolyether with a terminal carboxylic acid group (Krytox 157FSH (1)), chiefly in FC-72 (a mixture of perfluorohexanes). In particular, we were interested in whether or not proton transfer occurs, and if so, under what conditions in H-bonded complexes. Continuous variations experiments show that in FC-72 weaker bases (pyrazine, pyrimidine, and quinazoline) form 1:1 complexes with 1, whereas stronger bases (quinoline, pyridine, and isoquinoline) form 1:3 complexes. Ultraviolet and infrared spectral signatures reveal that the 1:1 complexes are molecular (B.HA) whereas the 1:3 complexes are ionic (BH+.A-HAHA). Infrared spectra of 1:3 ionic complexes are discussed in detail. Literature and experimental data on complexes between N-heterocyclic bases and carboxylic acids in a range of solvents are compiled to compare solvent effects on proton transfer. Polar solvents support ionic hydrogen bonds at a 1:1 mol ratio. In nonpolar organic solvents, ionic hydrogen bonds are only observed in complexes with 1:2 (base/acid) stoichiometries. In fluorous solvents, a larger excess of acid, 1:3, is necessary to facilitate proton transfer in hydrogen bonds between carboxylic acids and the bases studied.

  16. Virtual colorimetric sensor array: single ionic liquid for solvent discrimination.

    Science.gov (United States)

    Galpothdeniya, Waduge Indika S; Regmi, Bishnu P; McCarter, Kevin S; de Rooy, Sergio L; Siraj, Noureen; Warner, Isiah M

    2015-04-21

    There is a continuing need to develop high-performance sensors for monitoring organic solvents, primarily due to the environmental impact of such compounds. In this regard, colorimetric sensors have been a subject of intense research for such applications. Herein, we report a unique virtual colorimetric sensor array based on a single ionic liquid (IL) for accurate detection and identification of similar organic solvents and mixtures of such solvents. In this study, we employ eight alcohols and seven binary mixtures of ethanol and methanol as analytes to provide a stringent test for assessing the capabilities of this array. The UV-visible spectra of alcoholic solutions of the IL used in this study show two absorption bands. Interestingly, the ratio of absorbance for these two bands is found to be extremely sensitive to alcohol polarity. A virtual sensor array is created by using four different concentrations of IL sensor, which allowed identification of these analytes with 96.4-100% accuracy. Overall, this virtual sensor array is found to be very promising for discrimination of closely related organic solvents.

  17. Deep eutectic solvents: sustainable media for nanoscale and functional materials.

    Science.gov (United States)

    Wagle, Durgesh V; Zhao, Hua; Baker, Gary A

    2014-08-19

    Deep eutectic solvents (DESs) represent an alternative class of ionic fluids closely resembling room-temperature ionic liquids (RTILs), although, strictly speaking, they are distinguished by the fact that they also contain an organic molecular component (typically, a hydrogen bond donor like a urea, amide, acid, or polyol), frequently as the predominant constituent. Practically speaking, DESs are attractive alternatives to RTILs, sharing most of their remarkable qualities (e.g., tolerance to humidity, negligible vapor pressure, thermostability, wide electrochemical potential windows, tunability) while overcoming several limitations associated with their RTIL cousins. Particularly, DESs are typically, less expensive, more synthetically accessible (typically, from bulk commodity chemicals using solvent/waste-free processes), nontoxic, and biodegradable. In this Account, we provide an overview of DESs as designer solvents to create well-defined nanomaterials including shape-controlled nanoparticles, electrodeposited films, metal-organic frameworks, colloidal assemblies, hierarchically porous carbons, and DNA/RNA architectures. These breakthroughs illustrate how DESs can fulfill multiple roles in directing chemistry at the nanoscale: acting as supramolecular template, metal/carbon source, sacrificial agent (e.g., ammonia release from urea), and/or redox agent, all in the absence of formal stabilizing ligand (here, solvent and stabilizer are one and the same). The ability to tailor the physicochemical properties of DESs is central to controlling their interfacial behavior. The preorganized "supramolecular" nature of DESs provides a soft template to guide the formation of bimodal porous carbon networks or the evolution of electrodeposits. A number of essential parameters (viscosity, polarity, surface tension, hydrogen bonding), plus coordination with solutes/surfaces, all play significant roles in modulating species reactivity and mass transport properties governing the

  18. Mn(II)-coordinated Fluorescent Carbon Dots: Preparation and Discrimination of Organic Solvents

    Science.gov (United States)

    Wang, Yuru; Wang, Tianren; Chen, Xi; Xu, Yang; Li, Huanrong

    2018-04-01

    Herein, we prepared a Mn(II)-coordinated carbon dots (CDs) with fluorescence and MRI (magnetic resonance imaging) bimodal properties by a one-pot solvothermal method and separated via silica column chromatography. The quantum yield of the CDs increased greatly from 2.27% to 6.75% with increase of Mn(II) doping, meanwhile the CDs exhibited a higher MR activity (7.28 mM-1s-1) than that of commercial Gd-DTPA (4.63 mM-1s-1). In addition, white light emitting CDs were obtained by mixing the different types of CDs. Notably, these CDs exhibited different fluorescence emissions in different organic solvents and could be used to discriminate organic solvents based on the polarity and protonation of the solvents.

  19. Porous polymeric membranes with thermal and solvent resistance

    KAUST Repository

    Pulido, Bruno

    2017-05-30

    Polymeric membranes are highly advantageous over their ceramic counterparts in terms of the simplicity of the manufacturing process, cost and scalability. Their main disadvantages are low stability at temperatures above 200 °C, and in organic solvents. We report for the first time porous polymeric membranes manufactured from poly(oxindolebiphenylylene) (POXI), a polymer with thermal stability as high as 500 °C in oxidative conditions. The membranes were prepared by solution casting and phase inversion by immersion in water. The asymmetric porous morphology was characterized by scanning electronic microscopy. The pristine membranes are stable in alcohols, acetone, acetonitrile and hexane, as well as in aqueous solutions with pH between 0 and 14. The membrane stability was extended for application in other organic solvents by crosslinking, using various dibromides, and the efficiency of the different crosslinkers was evaluated by thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). POXI crosslinked membranes are stable up to 329 °C in oxidative conditions and showed organic solvent resistance in polar aprotic solvents with 99% rejection of Red Direct 80 in DMF at 70 °C. With this development, the application of polymeric membranes could be extended to high temperature and harsh environments, fields currently dominated by ceramic membranes.

  20. Molecular accessibility in solvent swelled coals. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kispert, L.D.

    1994-04-01

    The conversion of coal by an economically feasible catalytic method requires the catalyst to diffuse into the coal sample so that hydrogenation catalysis can occur from within as well as the normal surface catalysis. Thus an estimate of the size, shape, and reactivity, of the pores in the coal before and after the swelling with different solvents is needed so that an optimum sized catalyst will be used. This study characterizes the accessible area found in Argonne Premium Coal Samples (APCS) using a EPR spin probe technique. The properties deduced in this manner correlate well with the findings deduced from SANS, NMR, SEM, SAXS and light scattering measurements. The use of nitroxide spin probes with swelling solvents is a simple way in which to gain an understanding of the pore structure of coals, how it changes in the presence of swelling solvents and the chemistry that occurs at the pore wall. Hydrogen bonding sites occur primarily in low-rank coals and vary in reactive strength as rank is varied. Unswelled coals contain small, spherical pores which disappear when coal is swelled in the presence of polar solvents. Swelling studies of polystyrene-divinyl benzene copolymers implied that coal is polymeric, contains significant quantities of covalent cross-links and the covalent cross-link density increases with rank.

  1. Control of Electronic Conduction at an Oxide Heterointerface using Surface Polar Adsorbates

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Christopher

    2011-08-19

    We study the effect of the surface adsorption of a variety of common laboratory solvents on the conductivity at the interface between LaAlO{sub 3} and SrTiO{sub 3}. This interface possesses a range of intriguing physics, notably a proposed connection between the surface state of the LaAlO{sub 3} and the conductivity buried in the SrTiO{sub 3}. We show that the application of chemicals such as acetone, ethanol, and water can induce a large change (factor of three) in the conductivity. This phenomenon is observed only for polar solvents. These data provide experimental evidence for a general polarization-facilitated electronic transfer mechanism.

  2. Pressure and solvent shifts of charge transfer absorption band of iodine complexes

    International Nuclear Information System (INIS)

    Sawamura, Seiji; Taniguchi, Yoshihiro; Suzuki, Keizo

    1979-01-01

    Absorption spectra of the CT band of I 2 complexes were observed in several nonpolar solvents at 1 bar, and in heptane up to 4400 bar. All solvent shifts were red with an increase in (n 2 - 1)/(2n 2 + 1), the refractive index (n) function of solvents, consistent with the solvent shift theory. On the other hand pressure caused a variety of shifts, that is, red shifts in benzene-, toluene-, and mesitylene-I 2 complexes, an inversion shift from red to blue in HMB-I 2 complex, and blue shifts in Et 3 N-, n-Pr 3 N-, and n-Bu 3 N-I 2 complexes, though increase in pressure invariably raises the (n 2 - 1)/(2n 2 + 1) value of solvent. The pressure shifts of I 2 complexes seem to be interpreted by a sum of two effects. One is the increased polarity of the solvent, which causes a red shift. The other is the decrease in the bond distance between a donor and an acceptor, which contributes to a blue shift in a strong CT complex and to a red shift in a week one. The pressure and solvent shifts of I 2 complexes were compared with those of π-donor-TCNE complexes. (author)

  3. Spatiotemporal polarization gradients in phase-bearing light

    International Nuclear Information System (INIS)

    Lembessis, V. E.; Babiker, M.

    2010-01-01

    It is shown how the interference of two circularly polarized laser beams endowed with orbital angular momentum can give rise to spatial and temporal polarization gradients, displaying axial as well as angular symmetry properties. Illustrations are given with reference to circularly polarized Laguerre-Gaussian beams as typical light beams carrying orbital angular momentum.

  4. Micron-sized columnar grains of CH3NH3PbI3 grown by solvent-vapor assisted low-temperature (75 °C) solid-state reaction: The role of non-coordinating solvent-vapor

    Science.gov (United States)

    Zheng, Huifeng; Liu, Yangqiao; Sun, Jing

    2018-04-01

    The preparation of hybrid perovskite films with large columnar grains via low-temperature solid-state reaction remains a big challenge. Conventional solvent annealing using DMF, DMSO and ethanol, etc. fails to work effectively at low temperature (solar cells based on benzyl-alcohol-vapor annealing (75 °C), delivered much higher photovoltaic performance, better stability and smaller hysteresis than those based on conventional thermal annealing. Additionally, a champion power conversion efficiency (PCE) of 15.1% was obtained and the average PCE reached 12.2% with a tiny deviation. Finally, the mechanism of solvent annealing with non-coordinating solvent was discussed. Moreover, we revealed that high polarity and high boiling point of the solvent used for generating vapor, was critical to grow micron-sized columnar grains at such a low temperature (75 °C). This work will contribute to understanding the mechanism of grain growth in solvent annealing and improving its facility and effectiveness.

  5. [Inventory and environmental impact of VOCs emission from the typical anthropogenic sources in Sichuan province].

    Science.gov (United States)

    Han, Li; Wang, Xing-Rui; He, Min; Guo, Wei-Guang

    2013-12-01

    Based on Sichuan province environmental statistical survey data and other relevant activity data, volatile organic compounds (VOCs) emissions from typical anthropogenic sources in Sichuan province were calculated for the year of 2011 by applying the emission factor method. Besides, ozone and secondary organic aerosol formation potentials of these typical anthropogenic sources were discussed. The total VOC emission from these sources was about 482 kt in Sichuan province, biomass burning, solvent utilization, industrial processes, storage and distribution of fuel, and fossil fuel combustion contributed 174 kt, 153 kt, 121 kt, 21 kt and 13 kt, respectively; architecture wall painting, furniture coating, wood decoration painting and artificial board were the major emission sectors of the solvent utilization; while for the industrial processes, 19.4% of VOCs emission was from the wine industry. Chengdu was the largest contributor compared to the other cities in Sichuan, whose VOCs emission from these typical anthropogenic sources in 2011 was 112 kt. OFP of these sources was 1,930 kt altogether. Solvent utilization contributed 50.5% of the total SOA formation potentials, biomass burning and industrial processes both contributed about 23% , with storage and distribution of fuel and fossil fuel combustion accounting for 1% and 1.4%, respectively.

  6. Discrete and continuum modeling of solvent effects in a twisted intramolecular charge transfer system: The 4-N,N-dimethylaminobenzonitrile (DMABN) molecule.

    Science.gov (United States)

    Modesto-Costa, Lucas; Borges, Itamar

    2018-08-05

    The 4-N,N-dimethylaminobenzonitrile (DMABN) molecule is a prototypical system displaying twisted intramolecular (TICT) charge transfer effects. The ground and the first four electronic excited states (S 1 -S 4 ) in gas phase and upon solvation were studied. Charge transfer values as function of the torsion angle between the donor group (dimethylamine) and the acceptor moiety (benzonitrile) were explicitly computed. Potential energy curves were also obtained. The algebraic diagrammatic construction method at the second-order [ADC(2)] ab initio wave function was employed. Three solvents of increased polarities (benzene, DMSO and water) were investigated using discrete (average solvent electrostatic configuration - ASEC) and continuum (conductor-like screening model - COSMO) models. The results for the S 3 and S 4 excited states and the S 1 -S 4 charge transfer curves were not previously available in the literature. Electronic gas phase and solvent vertical spectra are in good agreement with previous theoretical and experimental results. In the twisted (90°) geometry the optical oscillator strengths have negligible values even for the S 2 bright state. Potential energy curves show two distinct pairs of curves intersecting at decreasing angles or not crossing in the more polar solvents. Charge transfer and electric dipole values allowed the rationalization of these results. The former effects are mostly independent of the solvent model and polarity. Although COSMO and ASEC solvent models mostly lead to similar results, there is an important difference: some crossings of the excitation energy curves appear only in the ASEC solvation model, which has important implications to the photochemistry of DMABN. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Separation of polar betalain pigments from cacti fruits of Hylocereus polyrhizus by ion-pair high-speed countercurrent chromatography.

    Science.gov (United States)

    Wybraniec, Sławomir; Stalica, Paweł; Jerz, Gerold; Klose, Bettina; Gebers, Nadine; Winterhalter, Peter; Spórna, Aneta; Szaleniec, Maciej; Mizrahi, Yosef

    2009-10-09

    Polar betacyanin pigments together with betaxanthins from ripe cactus fruits of Hylocereus polyrhizus (Cactaceae) were fractionated by means of preparative ion-pair high-speed countercurrent chromatography (IP-HSCCC) also using the elution-extrusion (EE) approach for a complete pigment recovery. HSCCC separations were operated in the classical 'head-to-tail' mode with an aqueous mobile phase. Different CCC solvent systems were evaluated in respect of influence and effectiveness of fractionation capabilities to separate the occurring pigment profile of H. polyrhizus. For that reason, the additions of two different volatile ion-pair forming perfluorinated carboxylic acids (PFCA) were investigated. For a direct comparison, five samples of Hylocereus pigment extract were run on preparative scale (900 mg) in 1-butanol-acetonitrile-aqueous TFA 0.7% (5:1:6, v/v/v) and the modified systems tert.-butyl methyl ether-1-butanol-acetonitrile-aqueous PFCA (2:2:1:5, v/v/v/v) using 0.7% and 1.0% trifluoroacetic acid (TFA) or heptafluorobutyric acid (HFBA) in the aqueous phase, respectively. The chemical affinity to the organic stationary CCC solvent phases and in consequence the retention of these highly polar betalain pigments was significantly increased by the use of the more lipophilic fluorinated ion-pair reagent HFBA instead of TFA. The HFBA additions separated more effectively the typical cacti pigments phyllocactin and hylocerenin from betanin as well as their iso-forms. Unfortunately, similar K(D) ratios and selectivity factors alpha around 1.0-1.1 in all tested solvent systems proved that the corresponding diastereomers, 15S-type pigments cannot be resolved from the 15R-epimers (iso-forms). Surprisingly, additions of the stronger ion-pair reagent (HFBA) resulted in a partial separation of hylocerenin from phyllocactin which were not resolved in the other solvent systems. The pigments were detected by means of HPLC-DAD and HPLC-electrospray ionization-MS using also

  8. A class of fluorescent heterocyclic dyes revisited: photophysics, structure, and solvent effects

    DEFF Research Database (Denmark)

    Zhu, Lianjie; Jensen, Hans-Christian Becker; Henriksen, Lars

    2009-01-01

    The photophysical behavior of a series of 2-methylthio-5-(Z-carbonyl)thieno-[3,4-e]-3,4-dihydro-1,2,3-triazine-4-ones was investigated by absorption and emission spectroscopy in a range of solvents representing a systematic variation in polarity, polarizability, as well as hydrogen bond donating ...

  9. Metal retention in human transferrin: consequences of solvent composition in analytical sample preparation methods.

    Science.gov (United States)

    Quarles, C Derrick; Randunu, K Manoj; Brumaghim, Julia L; Marcus, R Kenneth

    2011-10-01

    The analysis of metal-binding proteins requires careful sample manipulation to ensure that the metal-protein complex remains in its native state and the metal retention is preserved during sample preparation or analysis. Chemical analysis for the metal content in proteins typically involves some type of liquid chromatography/electrophoresis separation step coupled with an atomic (i.e., inductively coupled plasma-optical emission spectroscopy or -mass spectrometry) or molecular (i.e., electrospray ionization-mass spectrometry) analysis step that requires altered-solvent introduction techniques. UV-VIS absorbance is employed here to monitor the iron content in human holo-transferrin (Tf) under various solvent conditions, changing polarity, pH, ionic strength, and the ionic and hydrophobic environment of the protein. Iron loading percentages (i.e. 100% loading equates to 2 Fe(3+):1 Tf) were quantitatively determined to evaluate the effect of solvent composition on the retention of Fe(3+) in Tf. Maximum retention of Fe(3+) was found in buffered (20 mM Tris) solutions (96 ± 1%). Exposure to organic solvents and deionized H(2)O caused release of ~23-36% of the Fe(3+) from the binding pocket(s) at physiological pH (7.4). Salt concentrations similar to separation conditions used for ion exchange had little to no effect on Fe(3+) retention in holo-Tf. Unsurprisingly, changes in ionic strength caused by additions of guanidine HCl (0-10 M) to holo-Tf resulted in unfolding of the protein and loss of Fe(3+) from Tf; however, denaturing and metal loss was found not to be an instantaneous process for additions of 1-5 M guanidinium to Tf. In contrast, complete denaturing and loss of Fe(3+) was instantaneous with ≥6 M additions of guanidinium, and denaturing and loss of iron from Tf occurred in parallel proportions. Changes to the hydrophobicity of Tf (via addition of 0-14 M urea) had less effect on denaturing and release of Fe(3+) from the Tf binding pocket compared to changes

  10. Plasma polarization spectroscopy. History and future prospects

    International Nuclear Information System (INIS)

    Fujimoto, Takashi

    2002-01-01

    An intuitive account is given of the polarized emission line of atoms and ions, both classically and quantum mechanically. Polarization is a result of the population imbalance among the magnetic sublevels, or of the alignment, in the upper level. The history of Plasma Polarization Spectroscopy (PPS) is reviewed. Various polarization phenomena are divided into three classes. For each of the classes, typical experiments undertaken so far are reviewed. The advantages, limitations, and challenges regarding PPS are discussed. (author)

  11. Efficient Regeneration of Physical and Chemical Solvents for CO2 Capture

    Energy Technology Data Exchange (ETDEWEB)

    Tande, Brian [Univ. of North Dakota, Grand Forks, ND (United States); Seames, Wayne [Univ. of North Dakota, Grand Forks, ND (United States); Benson, Steve [Univ. of North Dakota, Grand Forks, ND (United States)

    2013-12-01

    The objective of this project was to evaluate the use of composite polymer membranes and porous membrane contactors to regenerate physical and chemical solvents for capture of carbon dioxide (CO2) from synthesis gas or flue gas, with the goal of improving the energy efficiency of carbon capture. Both a chemical solvent (typical for a post-combustion capture of CO2 from flue gas) and a physical solvent (typical for pre- combustion capture of CO2 from syngas) were evaluated using two bench-scale test systems constructed for this project. For chemical solvents, polytetrafluoroethylene and polypropylene membranes were found to be able to strip CO2 from a monoethanolamine (MEA) solution with high selectivity without significant degradation of the material. As expected, the regeneration temperature was the most significant parameter affecting the CO2 flux through the membrane. Pore size was also found to be important, as pores larger than 5 microns lead to excessive pore wetting. For physical solvents, polydimethyl-siloxane (PDMS)-based membranes were found to have a higher CO2 permeability than polyvinylalcohol (PVOH) based membranes, while also minimizing solvent loss. Overall, however, the recovery of CO2 in these systems is low – less than 2% for both chemical and physical solvents – primarily due to the small surface area of the membrane test apparatus. To obtain the higher regeneration rates needed for this application, a much larger surface area would be needed. Further experiments using, for example, a hollow fiber membrane module could determine if this process could be commercially viable.

  12. Solvent Dependency in the Quantum Efficiency of 4-[(4-Aminophenyl)-(4-imino-1-cyclohexa-2, 5- dienylidene) methyl] Aniline Hydrochloride.

    Science.gov (United States)

    Pathrose, Bini; Nampoori, V P N; Radhakrishnan, P; Sahira, H; Mujeeb, A

    2015-05-01

    In the present work dual beam thermal lens technique is used for studying the solvent dependency on the quantum efficiency of a novel dye used for biomedical applications. The role of solvent in the absolute fluorescence quantum yield of 4-[(4-Aminophenyl)-(4-imino-1-cyclohexa-2, 5- dienylidene) methyl] aniline hydrochloride is studied using thermal lens technique. It is observed that the variation in solvents and its concentration results considerable variations in the fluorescence quantum yield. These variations are due to the non-radiative relaxation of the absorbed energy and because of the different solvent properties. The highest quantum yield of the dye is observed in the polar protic solvent-water.

  13. Nickel-Catalyzed Suzuki-Miyaura Cross-Coupling in a Green Alcohol Solvent for an Undergraduate Organic Chemistry Laboratory

    Science.gov (United States)

    Hie, Liana; Chang, Jonah J.; Garg, Neil K.

    2015-01-01

    A modern undergraduate organic chemistry laboratory experiment involving the Suzuki-Miyaura coupling is reported. Although Suzuki-Miyaura couplings typically employ palladium catalysts in environmentally harmful solvents, this experiment features the use of inexpensive nickel catalysis, in addition to a "green" alcohol solvent. The…

  14. Hydrodynamic instabilities and concentration polarization coupled by osmotic pressure in a Taylor-Couette cell

    Science.gov (United States)

    Martinand, Denis; Tilton, Nils

    2016-11-01

    This study addresses analytically and numerically the coupling between hydrodynamic instabilities and osmotic pressure driven by concentration polarization. The configuration consists of a Taylor-Couette cell filled with a Newtonian fluid carrying a passive scalar. Whereas the concentric inner and outer cylinders are membranes permeable to the solvent, they totally reject the scalar. As a radial in- or outflow of solvent is imposed through both cylinders, a concentration boundary layer develops on the cylinder where the solvent exits, until an equilibrium steady state is reached. In addition, the rotation of the inner cylinder is used to drive centrifugal instabilities in the form of toroidal vortices, which interact with the concentration boundary layer. By means of the osmotic pressure, concentration polarization is found to promote or hinder the hydrodynamic instabilities, depending on capacity of the vortices and diffusion to increase the concentration field at the membrane. The results obtained by analytical stability analysis agree with dedicated Direct Numerical Simulations.

  15. Potential of mean force for ion pairs in non-aqueous solvents. Comparison of polarizable and non-polarizable MD simulations

    Science.gov (United States)

    Odinokov, A. V.; Leontyev, I. V.; Basilevsky, M. V.; Petrov, N. Ch.

    2011-01-01

    Potentials of mean force (PMF) are calculated for two model ion pairs in two non-aqueous solvents. Standard non-polarizable molecular dynamics simulation (NPMD) and approximate polarizable simulation (PMD) are implemented and compared as tools for monitoring PMF profiles. For the polar solvent (dimethylsulfoxide, DMSO) the PMF generated in terms of the NPMD reproduces fairly well the refined PMD-PMF profile. For the non-polar solvent (benzene) the conventional NPMD computation proves to be deficient. The validity of the correction found in terms of the approximate PMD approach is verified by its comparison with the result of the explicit PMD computation in benzene. The shapes of the PMF profiles in DMSO and in benzene are quite different. In DMSO, owing to dielectric screening, the PMF presents a flat plot with a shallow minimum positioned in the vicinity of the van der Waals contact of the ion pair. For the benzene case, the observed minimum proves to be unexpectedly deep, which manifests the formation of a tightly-binded contact ion pair. This remarkable effect arises owing to the strong electrostatic interaction that is incompletely screened by a non-polar medium. The PMFs for the binary benzene/DMSO mixtures display intermediate behaviour depending on the DMSO content.

  16. Solvent selection methodology for pharmaceutical processes: Solvent swap

    DEFF Research Database (Denmark)

    Papadakis, Emmanouil; Kumar Tula, Anjan; Gani, Rafiqul

    2016-01-01

    A method for the selection of appropriate solvents for the solvent swap task in pharmaceutical processes has been developed. This solvent swap method is based on the solvent selection method of Gani et al. (2006) and considers additional selection criteria such as boiling point difference...... in pharmaceutical processes as well as new solvent swap alternatives. The method takes into account process considerations such as batch distillation and crystallization to achieve the swap task. Rigorous model based simulations of the swap operation are performed to evaluate and compare the performance...

  17. Photo-dynamics of roseoflavin and riboflavin in aqueous and organic solvents

    International Nuclear Information System (INIS)

    Zirak, P.; Penzkofer, A.; Mathes, T.; Hegemann, P.

    2009-01-01

    Roseoflavin (8-dimethylamino-8-demethyl-D-riboflavin) and riboflavin in aqueous and organic solvents are studied by optical absorption spectroscopy, fluorescence spectroscopy, and fluorescence decay kinetics. Solvent polarity dependent absorption shifts are observed. The fluorescence quantum yields are solvent dependent. For roseoflavin the fluorescence decay shows a bi-exponential dependence (ps to sub-ps time constant, and 100 ps to a few ns time constant). The roseoflavin photo-dynamics is explained in terms of fast intra-molecular charge transfer (diabatic electron transfer) from the dimethylamino electron donor group to the pteridin carbonyl electron acceptor followed by intra-molecular charge recombination. The fast fluorescence component is due to direct locally-excited-state emission, and the slow fluorescence component is due to delayed locally-excited-state emission and charge transfer state emission. The fluorescence decay of riboflavin is mono-exponential. The S 1 -state potential energy surface is determined by vibronic relaxation and solvation dynamics due to excited-state dipole moment changes (adiabatic optical electron transfer).

  18. Photo-dynamics of roseoflavin and riboflavin in aqueous and organic solvents

    Science.gov (United States)

    Zirak, P.; Penzkofer, A.; Mathes, T.; Hegemann, P.

    2009-03-01

    Roseoflavin (8-dimethylamino-8-demethyl- D-riboflavin) and riboflavin in aqueous and organic solvents are studied by optical absorption spectroscopy, fluorescence spectroscopy, and fluorescence decay kinetics. Solvent polarity dependent absorption shifts are observed. The fluorescence quantum yields are solvent dependent. For roseoflavin the fluorescence decay shows a bi-exponential dependence (ps to sub-ps time constant, and 100 ps to a few ns time constant). The roseoflavin photo-dynamics is explained in terms of fast intra-molecular charge transfer (diabatic electron transfer) from the dimethylamino electron donor group to the pteridin carbonyl electron acceptor followed by intra-molecular charge recombination. The fast fluorescence component is due to direct locally-excited-state emission, and the slow fluorescence component is due to delayed locally-excited-state emission and charge transfer state emission. The fluorescence decay of riboflavin is mono-exponential. The S 1-state potential energy surface is determined by vibronic relaxation and solvation dynamics due to excited-state dipole moment changes (adiabatic optical electron transfer).

  19. Photo-dynamics of roseoflavin and riboflavin in aqueous and organic solvents

    Energy Technology Data Exchange (ETDEWEB)

    Zirak, P. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany); Penzkofer, A., E-mail: alfons.penzkofer@physik.uni-regensburg.de [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany); Mathes, T.; Hegemann, P. [Institut fuer Biologie/Experimentelle Biophysik, Humboldt Universitaet zu Berlin, Invalidenstrasse 42, D-10115 Berlin (Germany)

    2009-03-30

    Roseoflavin (8-dimethylamino-8-demethyl-D-riboflavin) and riboflavin in aqueous and organic solvents are studied by optical absorption spectroscopy, fluorescence spectroscopy, and fluorescence decay kinetics. Solvent polarity dependent absorption shifts are observed. The fluorescence quantum yields are solvent dependent. For roseoflavin the fluorescence decay shows a bi-exponential dependence (ps to sub-ps time constant, and 100 ps to a few ns time constant). The roseoflavin photo-dynamics is explained in terms of fast intra-molecular charge transfer (diabatic electron transfer) from the dimethylamino electron donor group to the pteridin carbonyl electron acceptor followed by intra-molecular charge recombination. The fast fluorescence component is due to direct locally-excited-state emission, and the slow fluorescence component is due to delayed locally-excited-state emission and charge transfer state emission. The fluorescence decay of riboflavin is mono-exponential. The S{sub 1}-state potential energy surface is determined by vibronic relaxation and solvation dynamics due to excited-state dipole moment changes (adiabatic optical electron transfer).

  20. Natural deep eutectic solvents as new potential media for green technology

    International Nuclear Information System (INIS)

    Dai, Yuntao; Spronsen, Jaap van; Witkamp, Geert-Jan; Verpoorte, Robert; Choi, Young Hae

    2013-01-01

    Highlights: ► Natural products were used as a source for deep eutectic solvents and ionic liquids. ► We define own chemical and physical properties of natural deep eutectic solvents. ► Interaction between natural deep eutectic solvents and solutes was confirmed by NMR. ► The developed natural deep eutectic solvents were applied as green media. - Abstract: Developing new green solvents is one of the key subjects in Green Chemistry. Ionic liquids (ILs) and deep eutectic solvents, thus, have been paid great attention to replace current harsh organic solvents and have been applied to many chemical processing such as extraction and synthesis. However, current ionic liquids and deep eutectic solvents have still limitations to be applied to a real chemical industry due to toxicity against human and environment and high cost of ILs and solid state of most deep eutectic solvents at room temperature. Recently we discovered that many plant abundant primary metabolites changed their state from solid to liquid when they were mixed in proper ratio. This finding made us hypothesize that natural deep eutectic solvents (NADES) play a role as alternative media to water in living organisms and tested a wide range of natural products, which resulted in discovery of over 100 NADES from nature. In order to prove deep eutectic feature the interaction between the molecules was investigated by nuclear magnetic resonance spectroscopy. All the tested NADES show clear hydrogen bonding between components. As next step physical properties of NADES such as water activity, density, viscosity, polarity and thermal properties were measured as well as the effect of water on the physical properties. In the last stage the novel NADES were applied to the solubilization of wide range of biomolecules such as non-water soluble bioactive natural products, gluten, starch, and DNA. In most cases the solubility of the biomolecules evaluated in this study was greatly higher than water. Based on the

  1. Natural deep eutectic solvents as new potential media for green technology

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Yuntao [Natural Products Laboratory, Institute of Biology, Leiden University, 2300 RA Leiden (Netherlands); Spronsen, Jaap van; Witkamp, Geert-Jan [Laboratory for Process Equipment, Delft University of Technology, Delft (Netherlands); Verpoorte, Robert [Natural Products Laboratory, Institute of Biology, Leiden University, 2300 RA Leiden (Netherlands); Choi, Young Hae, E-mail: y.choi@chem.leidenuniv.nl [Natural Products Laboratory, Institute of Biology, Leiden University, 2300 RA Leiden (Netherlands)

    2013-03-05

    Highlights: ► Natural products were used as a source for deep eutectic solvents and ionic liquids. ► We define own chemical and physical properties of natural deep eutectic solvents. ► Interaction between natural deep eutectic solvents and solutes was confirmed by NMR. ► The developed natural deep eutectic solvents were applied as green media. - Abstract: Developing new green solvents is one of the key subjects in Green Chemistry. Ionic liquids (ILs) and deep eutectic solvents, thus, have been paid great attention to replace current harsh organic solvents and have been applied to many chemical processing such as extraction and synthesis. However, current ionic liquids and deep eutectic solvents have still limitations to be applied to a real chemical industry due to toxicity against human and environment and high cost of ILs and solid state of most deep eutectic solvents at room temperature. Recently we discovered that many plant abundant primary metabolites changed their state from solid to liquid when they were mixed in proper ratio. This finding made us hypothesize that natural deep eutectic solvents (NADES) play a role as alternative media to water in living organisms and tested a wide range of natural products, which resulted in discovery of over 100 NADES from nature. In order to prove deep eutectic feature the interaction between the molecules was investigated by nuclear magnetic resonance spectroscopy. All the tested NADES show clear hydrogen bonding between components. As next step physical properties of NADES such as water activity, density, viscosity, polarity and thermal properties were measured as well as the effect of water on the physical properties. In the last stage the novel NADES were applied to the solubilization of wide range of biomolecules such as non-water soluble bioactive natural products, gluten, starch, and DNA. In most cases the solubility of the biomolecules evaluated in this study was greatly higher than water. Based on the

  2. Polarization patterns of the twilight sky

    Science.gov (United States)

    Cronin, Thomas W.; Warrant, Eric J.; Greiner, Birgit

    2005-08-01

    Although natural light sources produce depolarized light, patterns of partially linearly polarized light appear in the sky due to scattering from air molecules, dust, and aerosols. Many animals, including bees and ants, orient themselves to patterns of polarization that are present in daytime skies, when the intensity is high and skylight polarization is strong and predictable. The halicitid bee Megalopta genalis inhabits rainforests in Central America. Unlike typical bees, it forages before sunrise and after sunset, when light intensities under the forest canopy are very low, and must find its way to food sources and return to its nest in visually challenging circumstances. An important cue for the orientation could be patterns of polarization in the twilight sky. Therefore, we used a calibrated digital camera to image skylight polarization in an overhead patch of sky, 87.6° across, before dawn on Barro Colorado Island in Panama, where the bees are found. We simultaneously measured the spectral properties of polarized light in a cloudless patch of sky 15° across centered on the zenith. We also performed full-sky imaging of polarization before dawn and after dusk on Lizard Island in Australia, another tropical island. During twilight, celestial polarized light occurs in a wide band stretching perpendicular to the location of the hidden sun and reaching typical degrees of polarization near 80% at wavelengths >600 nm. This pattern appears about 45 minutes before local sunrise or disappears 45 minutes after local sunset (about 20 minutes after the onset of astronomical twilight at dawn, or before its end at dusk) and extends with little change through the entire twilight period. Such a strong and reliable orientation cue could be used for flight orientation by any animal with polarization sensitivity that navigates during twilight.

  3. Polarized targets at triangle universities nuclear laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Seely, M.L. [North Carolina State Univ., Raleigh, NC (United States); Gould, C.R. [North Carolina State Univ., Raleigh, NC (United States); Haase, D.G. [North Carolina State Univ., Raleigh, NC (United States); Huffman, P.R. [Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Keith, C.D. [North Carolina State Univ., Raleigh, NC (United States); Roberson, N.R. [Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Tornow, W. [Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Wilburn, W.S. [Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States)

    1995-03-01

    A summary of the polarized and aligned nuclear targets which have been constructed and used at the Triangle Universities Nuclear Laboratory is given. Statically polarized targets, typically operating at a temperature of 12 mK and a magnetic field of 7 T, have provided significant nuclear polarization in {sup 1}H, {sup 3}He, {sup 27}Al, {sup 93}Nb and {sup 165}Ho. A rotating, aligned {sup 165}Ho target is also in use. A {sup 3}He melting curve thermometer has been developed for use in statically polarized targets. A dynamically polarized proton target is under construction. ((orig.))

  4. Effect of extraction solvents on polyphenols and antioxidant activity of medicinal halophytes

    International Nuclear Information System (INIS)

    Qasim, M.; Aziz, I.; Gul, B.

    2016-01-01

    This study was conducted to determine the most effective solvent for extraction of polyphenols and antioxidant activity of medicinally important coastal halophytes (Thespesia populneoides, Salvadora persica, Ipomoea pes-caprae, Suaeda fruticosa and Pluchea lanceolata) known for high antioxidant potential. Five different solvents (water, 80% methanol, 80% ethanol, acetone and chloroform) were used to quantify polyphenols including total phenolic (TPC), total flavonoid (TFC) and proanthocyanidin contents (PC) and antioxidant capacity using DPPH radical scavenging and Ferric reducing antioxidant power (FRAP) activities. Among solvents of different polarities 80% methanol appeared most effective for polyphenol extraction. Thespesia populneoides had the highest polyphenols (TPC, TFC and PC) followed by Salvadora persica. Highest antioxidant activity was also found in T. populneoides and S. persica using the same solvent (80% methanol) which appeared better than synthetic antioxidants (BHA and BHT). The correlation analyses of each solvent showed strong to weak relationships among all studied parameters with maximum values (r and R2) in methanol followed by ethanol and water. Weaker correlation of acetone and chloroform indicates low capacity of these solvents both for polyphenol extraction and antioxidant activity. Our results reveal that aqueous methanol extracts of coastal halophytes had comparatively higher antioxidant activity than commercial antioxidants which indicate both their prospective efficacy and potential to replace synthetic derivatives from edible and medicinal products. (abstract)

  5. Exploring a multi-scale method for molecular simulation in continuum solvent model: Explicit simulation of continuum solvent as an incompressible fluid.

    Science.gov (United States)

    Xiao, Li; Luo, Ray

    2017-12-07

    We explored a multi-scale algorithm for the Poisson-Boltzmann continuum solvent model for more robust simulations of biomolecules. In this method, the continuum solvent/solute interface is explicitly simulated with a numerical fluid dynamics procedure, which is tightly coupled to the solute molecular dynamics simulation. There are multiple benefits to adopt such a strategy as presented below. At this stage of the development, only nonelectrostatic interactions, i.e., van der Waals and hydrophobic interactions, are included in the algorithm to assess the quality of the solvent-solute interface generated by the new method. Nevertheless, numerical challenges exist in accurately interpolating the highly nonlinear van der Waals term when solving the finite-difference fluid dynamics equations. We were able to bypass the challenge rigorously by merging the van der Waals potential and pressure together when solving the fluid dynamics equations and by considering its contribution in the free-boundary condition analytically. The multi-scale simulation method was first validated by reproducing the solute-solvent interface of a single atom with analytical solution. Next, we performed the relaxation simulation of a restrained symmetrical monomer and observed a symmetrical solvent interface at equilibrium with detailed surface features resembling those found on the solvent excluded surface. Four typical small molecular complexes were then tested, both volume and force balancing analyses showing that these simple complexes can reach equilibrium within the simulation time window. Finally, we studied the quality of the multi-scale solute-solvent interfaces for the four tested dimer complexes and found that they agree well with the boundaries as sampled in the explicit water simulations.

  6. Temperature dependence measurements and structural characterization of trimethyl ammonium ionic liquids with a highly polar solvent.

    Science.gov (United States)

    Attri, Pankaj; Venkatesu, Pannuru; Hofman, T

    2011-08-25

    We report the synthesis and characterization of a series of an ammonium ionic liquids (ILs) containing acetate, dihydrogen phosphate, and hydrogen sulfate anions with a common cation. To characterize the thermophysical properties of these newly synthesized ILs with the highly polar solvent N,N-dimethylformamide (DMF), precise measurements such as densities (ρ) and ultrasonic sound velocities (u) over the whole composition range have been performed at atmospheric pressure and over wide temperature ranges (25-50 °C). The excess molar volume (V(E)) and the deviation in isentropic compressibilities (Δκ(s)) were predicted using these temperature dependence properties as a function of the concentration of ILs. The Redlich-Kister polynomial was used to correlate the results. The ILs investigated in the present study included trimethylammonium acetate [(CH(3))(3)NH][CH(3)COO] (TMAA), trimethylammonium dihydrogen phosphate [(CH(3))(3)NH][H(2)PO(4)] (TMAP), and trimethylammonium hydrogen sulfate [(CH(3))(3)NH][HSO(4)] (TMAS). The intermolecular interactions and structural effects were analyzed on the basis of the measured and the derived properties. In addition, the hydrogen bonding between ILs and DMF has been demonstrated using semiempirical calculations with help of Hyperchem 7. A qualitative analysis of the results is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding between ILs and DMF molecules and their structural factors. The influence of the anion of the protic IL, namely, acetate (CH(3)COO), dihydrogen phosphate (H(2)PO(4)), and hydrogen sulfate (HSO(4)), on the thermophysical properties is also provided. © 2011 American Chemical Society

  7. The atomic structure of polar and non-polar InGaN quantum wells and the green gap problem

    Energy Technology Data Exchange (ETDEWEB)

    Humphreys, C.J., E-mail: colin.humphreys@msm.cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Griffiths, J.T., E-mail: jg641@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Tang, F., E-mail: ft274@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Oehler, F., E-mail: fabrice.oehler@lpn.cnrs.fr [CNRS/C2N, Paris Sud University, Route de Nozay, 91460 Marcoussis (France); Findlay, S.D., E-mail: scott.findlay@monash.edu [School of Physics and Astronomy, Monash University, Victoria 3800 (Australia); Zheng, C., E-mail: changlin.zheng@monash.edu [Monash Centre for Electron Microscopy, Monash University, Victoria 3800 (Australia); Etheridge, J., E-mail: joanne.etheridge@mcem.monash.edu [Department of Materials Science and Engineering, Monash University, Victoria 3800 (Australia); Martin, T.L., E-mail: tomas.martin@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Bagot, P.A.J., E-mail: paul.bagot@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Moody, M.P., E-mail: michael.moody@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Sutherland, D., E-mail: danny.sutherland@manchester.ac.uk [School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL (United Kingdom); Dawson, P., E-mail: philip.dawson@manchester.ac.uk [School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL (United Kingdom); Schulz, S., E-mail: stefan.schulz@tyndall.ie [Tyndall National Institute, Lee Maltings Complex, Dyke Parade, Cork (Ireland); and others

    2017-05-15

    Highlights: • We have studied the atomic structure of polar and non-polar InGaN quantum wells. • The non-polar (11-20) InGaN quantum wells contain indium-rich clusters, unlike the polar (0001) quantum wells. • The electrons and holes in the quantum wells are localised by different mechanisms. - Abstract: We have used high resolution transmission electron microscopy (HRTEM), aberration-corrected quantitative scanning transmission electron microscopy (Q-STEM), atom probe tomography (APT) and X-ray diffraction (XRD) to study the atomic structure of (0001) polar and (11-20) non-polar InGaN quantum wells (QWs). This paper provides an overview of the results. Polar (0001) InGaN in QWs is a random alloy, with In replacing Ga randomly. The InGaN QWs have atomic height interface steps, resulting in QW width fluctuations. The electrons are localised at the top QW interface by the built-in electric field and the well-width fluctuations, with a localisation energy of typically 20 meV. The holes are localised near the bottom QW interface, by indium fluctuations in the random alloy, with a localisation energy of typically 60 meV. On the other hand, the non-polar (11-20) InGaN QWs contain nanometre-scale indium-rich clusters which we suggest localise the carriers and produce longer wavelength (lower energy) emission than from random alloy non-polar InGaN QWs of the same average composition. The reason for the indium-rich clusters in non-polar (11-20) InGaN QWs is not yet clear, but may be connected to the lower QW growth temperature for the (11-20) InGaN QWs compared to the (0001) polar InGaN QWs.

  8. Review of Abiotic Degradation of Chlorinated Solvents by Reactive Iron Minerals

    Science.gov (United States)

    Abiotic degradation of chlorinated solvents by reactive iron minerals such as iron sulfides, magnetite, green rust, and other Fe(II)-containing minerals has been observed in both laboratory and field conditions. These reactive iron minerals typically form under iron and sulfate ...

  9. Reactivity of cyclohex-1-enylcarboxylic and 2-methylcyclohex-1-enylcarboxylic acids with diazodiphenylmethane in aprotic solvents

    Directory of Open Access Journals (Sweden)

    VERA V. KRSTIC

    2000-12-01

    Full Text Available Rate constants for the reaction of diazodiphenylmethane with cyclohex-1-enylcarboxylic acid and 2-methylcyclohex-1-enylcarboxylic acid were determined in nine aprotic solvents, as well as in seven protic solvents, at 30°C using the appropriate UV-spectroscopic method. In protic solvents the unsubsituted acid displayed higher reaction rates than the methyl-substituted one. The results in aprotic solvents showed quite the opposite, and the reaction rates were considerably lower. In order to explain the obtained results through solvent effects, reaction rate constants (k of the examined acids were correlated using the total solvatochromic equation of the form: log k=logk0+sp*+aa+bb, where p* is the measure of the solvent polarity, a represents the scale of the solvent hydrogen bond donor acidities (HBD and b represents the scale of the solvent hydrogen bond acceptor basicities (HBA. The correlation of the kinetic data were carried out by means of multiple linear regression analysis and the opposite effects of aprotic solvents, as well as the difference in the influence of protic and aprotic solvents on the reaction of the two examined acids with DDM were discussed. The results presented in this paper for cyclohex-1-enylcarboxylic and 2-methylcyclohex-1-enylcarboxylic acids were compared with the kinetic data for benzoic acid obtained in the same chemical reaction, under the same experimental conditions.

  10. High stability of few layer graphene nanoplatelets in various solvents

    KAUST Repository

    Xu, X; Zhou, Jian; Lubineau, Gilles

    2017-01-01

    Dispersion of few-layer graphene nanoplatelets (GNPs) in liquid media is a crucial step for various applications. Here, we highlight a simple, nondestructive method for preparing stable aqueous colloidal solutions with GNP powder quickly dispersed in 5 wt.% sodium–hypochlorite- (NaClO) and sodium-bromide- (NaBr) salted solvent by bath sonication. This method makes it possible to easily prepare a highly concentrated colloidal solution (1 mgcenterdotml−1) of GNPs that can easily be re-dispersed in water (treated GNPs). The aqueous suspension we prepared remained stable for longer than a few weeks. We made similar tests with various solvents and dispersibility appeared to decrease with decreasing polarity. High-concentration suspensions using our facile dispersion method could be of particular interest to the large community using graphene for a diversity of applications.

  11. High stability of few layer graphene nanoplatelets in various solvents

    KAUST Repository

    Xu, X

    2017-04-25

    Dispersion of few-layer graphene nanoplatelets (GNPs) in liquid media is a crucial step for various applications. Here, we highlight a simple, nondestructive method for preparing stable aqueous colloidal solutions with GNP powder quickly dispersed in 5 wt.% sodium–hypochlorite- (NaClO) and sodium-bromide- (NaBr) salted solvent by bath sonication. This method makes it possible to easily prepare a highly concentrated colloidal solution (1 mgcenterdotml−1) of GNPs that can easily be re-dispersed in water (treated GNPs). The aqueous suspension we prepared remained stable for longer than a few weeks. We made similar tests with various solvents and dispersibility appeared to decrease with decreasing polarity. High-concentration suspensions using our facile dispersion method could be of particular interest to the large community using graphene for a diversity of applications.

  12. CO2 Binding Organic Liquids Gas Capture with Polarity Swing Assisted Regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Heldebrant, David [Battelle Memorial Institute, Columbus, OH (United States)

    2014-05-31

    This report outlines the comprehensive bench-scale testing of the CO2-binding organic liquids (CO2BOLs) solvent platform and its unique Polarity Swing Assisted Regeneration (PSAR). This study outlines all efforts on a candidate CO2BOL solvent molecule, including solvent synthesis, material characterization, preliminary toxicology studies, and measurement of all physical, thermodynamic and kinetic data, including bench-scale testing. Equilibrium and kinetic models and analysis were made using Aspen Plus™. Preliminary process configurations, a technoeconomic assessment and solvent performance projections for separating CO2 from a subcritical coal-fired power plant are compared to the U.S. Department of Energy's Case 10 monoethanolamine baseline.

  13. Nonlocal Poisson-Fermi model for ionic solvent.

    Science.gov (United States)

    Xie, Dexuan; Liu, Jinn-Liang; Eisenberg, Bob

    2016-07-01

    We propose a nonlocal Poisson-Fermi model for ionic solvent that includes ion size effects and polarization correlations among water molecules in the calculation of electrostatic potential. It includes the previous Poisson-Fermi models as special cases, and its solution is the convolution of a solution of the corresponding nonlocal Poisson dielectric model with a Yukawa-like kernel function. The Fermi distribution is shown to be a set of optimal ionic concentration functions in the sense of minimizing an electrostatic potential free energy. Numerical results are reported to show the difference between a Poisson-Fermi solution and a corresponding Poisson solution.

  14. The effect of various solvents on the back channel of solution-processed In-Ga-Zn-O thin-film transistors intended for biosensor applications

    International Nuclear Information System (INIS)

    Kim, Si Joon; Jung, Joohye; Yoon, Doo Hyun; Kim, Hyun Jae

    2013-01-01

    This study investigated the effects of exposing solution-processed In-Ga-Zn-O (IGZO) thin-film transistors (TFTs), intended for biosensor applications, to various solvents. Various solvents, such as the nonpolar solvent chlorobenzene and the polar solvents ethanol and deionized (DI) water, were dropped and adsorbed on exposed IGZO channel surfaces. All IGZO TFT devices exhibited a negative threshold voltage shift and a sub-threshold swing degradation, without an accompanying degradation in field-effect mobility. These variations depended on the dielectric constant of the solvents; with the exception of the IGZO TFT device exposed to DI water, they all gradually returned to their initial states.

  15. Fabrication and characterization of poly(L-lactic acid) gels induced by fibrous complex crystallization with solvents

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Yasuhiro [ORNL; Fukatsu, Akinobu [Shizuoka University, Hamamatsu, Japan; Wang, Yangyang [ORNL; Miyamoto, Kazuaki [Shizuoka University, Hamamatsu, Japan; Mays, Jimmy [University of Tennessee, Knoxville (UTK); Tasaka, Shigeru [Shizuoka University, Hamamatsu, Japan

    2014-01-01

    Complex crystal induced gelation of poly(L-lactic acid) (PLLA) solutions was studied for a series of solvents, including N,N-dimethylformamide (DMF). By cooling the solutions prepared at elevated temperatures, PLLA gels were produced in solvents that induced complex crystals ( -crystals) with PLLA. Fibrous structure of PLLA in the gel with DMF was observed by polarizing optical microscopy, field emission electron microscopy, and atomic force microscopy. Upon heating, the crystal form of PLLA in the DMF gel changed from -crystal to a-crystal, the major crystal form in common untreated PLLA films, but the morphology and high elastic modulus of the gel remained until the a-crystal dissolved at higher temperature. In addition, a solvent exchanging method was developed, which allowed PLLA gels to be prepared in other useful solvents that do not induce -crystals without losing the morphology and mechanical properties.

  16. Use of solvent to regulate the degree of polymerisation in weakly associated supramolecular oligomers

    DEFF Research Database (Denmark)

    Bähring, Steffen; Kim, D. S.; Duedal, T.

    2014-01-01

    Using a tetrathiafulvalene functionalised calix[4] pyrrole (TTF-C[4]P; 1) and alkyl diester-linked bis-dinitrophenols (2-4), it was found that the solvent polarity and linker length have an effect on the molecular aggregation behaviour. 2D H-1 NOESY, DOSY NMR and UV-vis-NIR spectroscopic studies...

  17. Fotodegradação da 4-((4-N,N-dimetilamino-benzilideno-2-feniloxazolona em diferentes solventes orgânicos = Photodegradation of 4-((4-N,N-dimethylamine-benzylidene-2- phenyl-oxazolone in different organic solvents

    Directory of Open Access Journals (Sweden)

    Mauricio Ferreira da Rosa

    2007-07-01

    Full Text Available Foram sintetizados 13 derivados oxazolônicos, e o comportamento fotoquímico de um deles foi analisado em função da polaridade do solvente utilizado quando irradiado no comprimento de onda de 350 nm. Observou-se que, em solvente polar aprótico (acetonitrila, a degradação ocorre mais rapidamente que em solvente apolar. Verifica-se, nos espectros de absorção no UV-vis em função do tempo de irradiação em acetonitrila, a presença de um ponto isobéstico em 419 nm, mostrando que somente duas espécies coexistem no meio. A adição de um segundo solvente destrói este comportamento. Para osoutros solventes utilizados, não foi observada a presença de ponto isosbéstico.Thirteen (13 oxazolone derivatives were synthesized and the photochemical behavior of one of them was analyzed for solventpolarity when submitted to irradiation in 350 nm. When acetonitrile is used as solvent, photodegradation is faster when compared with n-hexane. The electronic spectra in acetonitrile showed an isosbestic point in 419 nm, indicating that only two species co-exist in solution. The addition of a second solvent destroyed this behavior. The others solvents did not show an isosbestic point.

  18. Solvent extraction

    Energy Technology Data Exchange (ETDEWEB)

    Coombs, D.M.; Latimer, E.G.

    1988-01-05

    It is an object of this invention to provide for the demetallization and general upgrading of heavy oil via a solvent extracton process, and to improve the efficiency of solvent extraction operations. The yield and demetallization of product oil form heavy high-metal content oil is maximized by solvent extractions which employ either or all of the following techniques: premixing of a minor amount of the solvent with feed and using countercurrent flow for the remaining solvent; use of certain solvent/free ratios; use of segmental baffle tray extraction column internals and the proper extraction column residence time. The solvent premix/countercurrent flow feature of the invention substantially improves extractions where temperatures and pressures above the critical point of the solvent are used. By using this technique, a greater yield of extract oil can be obtained at the same metals content or a lower metals-containing extract oil product can be obtained at the same yield. Furthermore, the premixing of part of the solvent with the feed before countercurrent extraction gives high extract oil yields and high quality demetallization. The solvent/feed ratio features of the invention substanially lower the captial and operating costs for such processes while not suffering a loss in selectivity for metals rejection. The column internals and rsidence time features of the invention further improve the extractor metals rejection at a constant yield or allow for an increase in extract oil yield at a constant extract oil metals content. 13 figs., 3 tabs.

  19. A whiff of death: fatal volatile solvent inhalation abuse.

    Science.gov (United States)

    Steffee, C H; Davis, G J; Nicol, K K

    1996-09-01

    Inhalation abuse of volatile solvents, previously known generically as "glue sniffing," is typically pursued by adolescents. A wide range of legal, easily obtained products containing volatile substances are available for abuse. We report two illustrative cases of fatal volatile substance abuse: gasoline sniffing in a 20-year-old man and aerosol propellant gas inhalation (aerosol air freshener) in a 16-year-old girl with underlying reactive airway disease. Although the ratio of deaths to nonfatal inhalation escapades is extremely low, volatile solvent abuse carries the risk of sudden death due to cardiac arrest after a dysrhythmia or vasovagal event, central nervous system respiratory depression, hypoxia and hypercapnia due to the techniques of inhalation, and other mechanisms. Investigation of the patient's substance abuse history, examination of the scene of death, and special toxicologic analyses are critical to identifying volatile substance inhalation abuse as the cause of death because anatomic autopsy findings will typically be nonspecific. Above all, physicians must suspect the diagnosis of volatile substance inhalation abuse, especially in any case of sudden death involving an otherwise healthy young person.

  20. Use of solvent mixtures for total lipid extraction of Chlorella vulgaris and gas chromatography FAME analysis.

    Science.gov (United States)

    Moradi-Kheibari, Narges; Ahmadzadeh, Hossein; Hosseini, Majid

    2017-09-01

    Lipid extraction is the bottleneck step for algae-based biodiesel production. Herein, 12 solvent mixture systems (mixtures of three non-polar and two polar organic solvents) were examined to evaluate their effects on the total lipid yield from Chlorella vulgaris (C. vulgaris). Moreover, the extraction yields of three solvent systems with maximum extraction efficiency of esterifiable lipids were determined by acidic transesterification and GC-FID analysis. Three solvent systems, which resulted in a higher extraction yield, were further subjected to fatty acid methyl ester (FAME) analysis. The total lipid extraction yields (based on dry biomass) were (38.57 ± 1.51), (25.33 ± 0.58), and (25.17 ± 1.14) %, for chloroform-methanol (1:2) (C1M2), hexane-methanol (1:2) (H1M2), and chloroform-methanol (2:1) (C2M1), respectively. The extraction efficiency of C1M2 was approximately 1.5 times higher than H1M2 and C2M1, whereas the FAME profile of extracted lipids by H1M2 and C1M2 were almost identical. Moreover, the esterifiable lipid extraction yields of (18.14 ± 2.60), (16.66 ± 0.35), and (13.22 ± 0.31) % (based on dry biomass) were obtained for C1M2, H1M2, and C2M1 solvent mixture systems, respectively. The biodiesel fuel properties produced from C. vulgaris were empirically predicted and compared to that of the EN 14214 and ASTM 6751 standard specifications.

  1. Phase Behavior and Evaporation Profile of Tween 20 - Eugenol System. Effect of Different Alkane Chain Length and Solvent System

    International Nuclear Information System (INIS)

    Kassim, A.; Lim, W.H.; Kuangl, D.; Rusmawati, W.W.M.; Abdullah, A.H.; Teoh, S.P.

    2003-01-01

    The isotropic region of Tween 20/eugenol/n-alkane in aqueous systems was determined. The solubilisation trend of isotropic solution formed in the presence of eugenol was studied as a function of different alkyl chain length of n-alkane. The solubility of solvent in surfactant solution is dependent on their molecular polarity. An increase in n-alkane chain length (lower polarity) lead to smaller isotropic region which will affect the surfactant partitioning between the interface, the oil phase and the aqueous phase of the microemulsion as the oil chain length is varied. The changes of evaporation behaviour were affected strongly by the types of phases existed in the systems. The increment of n-alkane and water content led to higher evaporation rate. But the formation of w/o microemulsion would lower the evaporation rate because water molecules were trapped in the core of aggregates. In solubilisation system, evaporation rate is dependent on the solvent content and the interaction between Tween 20 and solvent molecules in the mixed composition. (author)

  2. Polystyrene Microbeads by Dispersion Polymerization: Effect of Solvent on Particle Morphology

    Directory of Open Access Journals (Sweden)

    Lei Jinhua

    2014-01-01

    Full Text Available Polystyrene microspheres (PS were synthesized by dispersion polymerization in ethanol/2-Methoxyethanol (EtOH/EGME blend solvent using styrene (St as monomer, azobisisobutyronitrile (AIBN as initiator, and PVP (polyvinylpyrrolidone K-30 as stabilizer. The typical recipe of dispersion polymerization is as follows: St/Solvent/AIBN/PVP = 10 g/88 g/0.1 g/2 g. The morphology of polystyrene microspheres was characterized by the scanning electron microscopy (SEM and the molecular weights of PS particles were measured by the Ubbelohde viscometer method. The effect of ethanol content in the blend solvent on the morphology and molecular weight of polystyrene was studied. We found that the size of polystyrene microspheres increased and the molecular weight of polystyrene microspheres decreased with the decreasing of the ethanol content in the blend solvent from 100 wt% to 0 wt%. What is more, the size monodispersity of polystyrene microspheres was quite good when the pure ethanol or pure 2-Methoxyethanol was used; however when the blend ethanol/2-Methoxyethanol solvent was used, the polystyrene microspheres became polydisperse. We further found that the monodispersity of polystyrene microspheres can be significantly improved by adding a small amount of water into the blend solvent; the particles became monodisperse when the content of water in the blend solvent was up to 2 wt%.

  3. Ion and solvent diffusion and ion conduction of PC-DEC and PC-DME binary solvent electrolytes of LiN(SO2CF3)2

    International Nuclear Information System (INIS)

    Hayamizu, Kikuko; Aihara, Yuichi

    2004-01-01

    Two binary mixed solvent systems typically used for lithium batteries were studied by measuring the self-diffusion coefficients of the solvent, lithium ion and anion, independently by using the multi-nuclear pulsed field-gradient spin-echo (PGSE) 1 H, 7 Li and 19 F NMR method. One system was propylene carbonate (PC) and diethyl carbonate (DEC) system and the other binary system was PC and 1,2-dimethoxyethane (DME), and the lithium salt used was LiN(SO 2 CF 3 ) 2 (LiTFSI). The relative ratio of the PC was changed from zero (pure DME and DEC) to 100% (pure PC) in the DME-PC and the DEC-PC systems, respectively. The self-diffusion coefficients of the solvents were measured with and without the lithium salt, and the two solvents had almost the same diffusion coefficient in the DEC-PC system, while DME diffused faster than PC in the DME-PC system. In the electrolytes the solvents diffused the fastest, followed by the anion with the lithium ion diffusing the slowest. The degree of ion dissociation was estimated for each electrolyte by comparing the ionic conductivities estimated from the ion diffusion and those measured directly by the electrochemical method

  4. Polarization variablity among Wolf-Rayet stars. IV. A complete lack of circular polarization in the optical continuum

    International Nuclear Information System (INIS)

    Robert, C.; Moffat, A.F.J.

    1989-01-01

    Quasi-simultaneous blue and red, broadband optical monitoring in linear and circular polarization and in intensity has been carried out over an interval of three weeks for several Wolf-Rayet stars that show relatively large Delta P variations in linear polarization. No significant varying Delta V component of circular polarization is detected in any of these stars. The lower upper limit Delta V/Delta P implies that the intrinsic linearly polarized light which does vary cannot be produced by electrons gyrating in a magnetic field, unless they are ultrarelativistic - a rather unlikely situation. The low mean circular polarization typically observed is probably interstellar in origin. Lack of periodicity in the observed variations of linear polarization implies that even weak magnetic field loops are unlikely to be involved in confining pockets of wind plasma. The observed linear polarization variations are related mainly to electron scattering. 25 refs

  5. Canyon solvent cleaning

    International Nuclear Information System (INIS)

    Reif, D.J.

    1986-01-01

    The HM Process at the Savannah River Plant (SRP) uses 7.5% tributylphosphate in n-paraffin as an extraction solvent. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials that influence product losses, produce decontamination, and separation efficiencies. Laboratory studies to improve online solvent cleaning have shown the carbonate washing, although removing residual solvent activity does not remove binding ligands that hold fission products in the solvent. Treatment of solvent by an alumina adsorption process removes binding ligands and significantly improves recycle solvent performance. Both laboratory work defining a full-scale alumina adsorption process and the use of the process to clean HM Process first cycle solvent are presented

  6. Relation between separation factor of carbon isotope and chemical reaction of CO2 with amine in nonaqueous solvent

    International Nuclear Information System (INIS)

    Takeshita, Kenji; Kitamoto, Asashi

    1989-01-01

    The separation factor for carbon isotope exchange reaction between CO 2 and amine in nonaqueous solvent was related to absorption reaction of CO 2 in a solution. The test solutions were mixtures of primary amine (such as butylamine and tert-butylamine) or secondary amine (such as diethylamine, dipropylamine and dibutylamine) diluted with nonpolar solvent (octane or triethyalmine) or polar solvent (methanol), respectively. The isotope exchange reaction consists of three steps related to chemical reaction of CO 2 in amine and nonaqueous solvent mixture, namely the reaction between CO 2 and carbamic acid, that between CO 2 and amine carbamate, and that between CO 2 and carbamic ion. Above all, the isotope separation factor between CO 2 and carbamic acid had the highest value. The overall separation factor can be higher in amine-nonaqueous solvent mixture where the concentration of carbamic acid becomes higher. (author)

  7. Quantum Monte Carlo formulation of volume polarization in dielectric continuum theory

    NARCIS (Netherlands)

    Amovilli, Claudio; Filippi, Claudia; Floris, Franca Maria

    2008-01-01

    We present a novel formulation based on quantum Monte Carlo techniques for the treatment of volume polarization due to quantum mechanical penetration of the solute charge density in the solvent domain. The method allows to accurately solve Poisson’s equation of the solvation model coupled with the

  8. Imaging with Polarized Neutrons

    Directory of Open Access Journals (Sweden)

    Nikolay Kardjilov

    2018-01-01

    Full Text Available Owing to their zero charge, neutrons are able to pass through thick layers of matter (typically several centimeters while being sensitive to magnetic fields due to their intrinsic magnetic moment. Therefore, in addition to the conventional attenuation contrast image, the magnetic field inside and around a sample can be visualized by detecting changes of polarization in a transmitted beam. The method is based on the spatially resolved measurement of the cumulative precession angles of a collimated, polarized, monochromatic neutron beam that traverses a magnetic field or sample.

  9. Basicity comparison for di-substituted 4-nitropyridine derivatives in polar non-aqueous media

    International Nuclear Information System (INIS)

    Gurzynski, Lukasz; Puszko, Aniela; Chmurzynski, Lech

    2007-01-01

    Acid dissociation, as well as cationic homoconjugation equilibria have been studied potentiometrically in systems involving four di-substituted 4-nitropyridines and conjugate cationic acids in the polar non-aqueous solvents - aprotic protophobic acetonitrile (AN) and propylene carbonate (PC), the amphiprotic methanol (MeOH), and in the aprotic protophilic dimethyl sulfoxide (DMSO). The influence of solvent effect on the obtained acidity constants has been discussed. The acidity constants (expressed as pK a values) were compared with those previously determined in another polar protophobic aprotic solvent - acetone (AC), and obtained for the unsubstituted pyridine (Py). A comparison of the acid dissociation constants determined in all media studied has proved that the strength of the cationic acids increases on going from acetonitrile through propylene carbonate, acetone, and methanol to dimethyl sulfoxide. Furthermore, the values of acidity constants in the non-aqueous media have shown that in all the solvents studied they change according to the substituent effects. It has been also found that substituted 4-nitropyridine derivatives studied exhibit no tendency towards cationic homoconjugation in acetonitrile, propylene carbonate, and methanol and dimethyl sulfoxide. Moreover, it has been demonstrated that the acid dissociation constants determined by potentiometric titration method in all the solutions investigated correlate well with the calculated energy parameters of the protonation reactions in the gaseous phase

  10. Basicity comparison for di-substituted 4-nitropyridine derivatives in polar non-aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Gurzynski, Lukasz [Department of General and Inorganic Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Puszko, Aniela [Department of Organic Chemistry, School of Economics, Wroclaw (Poland); Chmurzynski, Lech [Department of General and Inorganic Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)], E-mail: lech@chemik.chem.univ.gda.pl

    2007-12-15

    Acid dissociation, as well as cationic homoconjugation equilibria have been studied potentiometrically in systems involving four di-substituted 4-nitropyridines and conjugate cationic acids in the polar non-aqueous solvents - aprotic protophobic acetonitrile (AN) and propylene carbonate (PC), the amphiprotic methanol (MeOH), and in the aprotic protophilic dimethyl sulfoxide (DMSO). The influence of solvent effect on the obtained acidity constants has been discussed. The acidity constants (expressed as pK{sub a} values) were compared with those previously determined in another polar protophobic aprotic solvent - acetone (AC), and obtained for the unsubstituted pyridine (Py). A comparison of the acid dissociation constants determined in all media studied has proved that the strength of the cationic acids increases on going from acetonitrile through propylene carbonate, acetone, and methanol to dimethyl sulfoxide. Furthermore, the values of acidity constants in the non-aqueous media have shown that in all the solvents studied they change according to the substituent effects. It has been also found that substituted 4-nitropyridine derivatives studied exhibit no tendency towards cationic homoconjugation in acetonitrile, propylene carbonate, and methanol and dimethyl sulfoxide. Moreover, it has been demonstrated that the acid dissociation constants determined by potentiometric titration method in all the solutions investigated correlate well with the calculated energy parameters of the protonation reactions in the gaseous phase.

  11. Cleanup of 7.5% tributyl phosphate/n-paraffin solvent-extraction solvent

    International Nuclear Information System (INIS)

    Reif, D.J.

    1987-02-01

    The HM process at the Savannah River Plant uses 7.5% tributyl phosphate in n-paraffin as an extraction solvent. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials which influence product losses, product decontamination, and separation efficiencies. Laboratory studies to improve online solvent cleaning have shown that carbonate washing, although removing residual solvent activity, does not remove binding ligands which hold fission products in the solvent. Treatment of solvent by an alumina adsorption process removes binding ligands and significantly improves recycle solvent performance. Both laboratory work defining a full-scale alumina adsorption process and the use of the process to clean HM process first cycle solvent is discussed

  12. A Solvent-Vapor Approach toward the Control of Block Ionomer Morphologies

    Energy Technology Data Exchange (ETDEWEB)

    Mineart, Kenneth P.; Lee, Byeongdu; Spontak, Richard J.

    2016-04-26

    Sulfonated block ionomers possess advantageous properties for a wide range of diverse applications such as desalination membranes, fuel cells, electroactive media, and photovoltaic devices. Unfortunately, their inherently high incompatibilities and glass transition temperatures e ff ectively prevent the use of thermal annealing, routinely employed to re fi ne the morphologies of nonionic block copolymers. An alternative approach is therefore required to promote morphological equilibration in block ionomers. The present study explores the morphological characteristics of midblock- sulfonated pentablock ionomers (SBIs) di ff ering in their degree of sulfonation (DOS) and cast from solution followed by solvent-vapor annealing (SVA). Transmission electron microscopy con fi rms that fi lms deposited from di ff erent solvent systems form nonequilibrium morphologies due to solvent-regulated self-assembly and drying. A series of SVA tests performed with solvents varying in polarity reveals that exposing cast fi lms to tetrahydrofuran (THF) vapor for at least 2 h constitutes the most e ff ective SVA protocol, yielding the anticipated equilibrium morphology. That is, three SBI grades subjected to THF-SVA self-assemble into well-ordered lamellae wherein the increase in DOS is accompanied by an increase in lamellar periodicity, as measured by small-angle X-ray scattering.

  13. Accuracy comparison of several common implicit solvent models and their implementations in the context of protein-ligand binding.

    Science.gov (United States)

    Katkova, E V; Onufriev, A V; Aguilar, B; Sulimov, V B

    2017-03-01

    In this study several commonly used implicit solvent models are compared with respect to their accuracy of estimating solvation energies of small molecules and proteins, as well as desolvation penalty in protein-ligand binding. The test set consists of 19 small proteins, 104 small molecules, and 15 protein-ligand complexes. We compared predicted hydration energies of small molecules with their experimental values; the results of the solvation and desolvation energy calculations for small molecules, proteins and protein-ligand complexes in water were also compared with Thermodynamic Integration calculations based on TIP3P water model and Amber12 force field. The following implicit solvent (water) models considered here are: PCM (Polarized Continuum Model implemented in DISOLV and MCBHSOLV programs), GB (Generalized Born method implemented in DISOLV program, S-GB, and GBNSR6 stand-alone version), COSMO (COnductor-like Screening Model implemented in the DISOLV program and the MOPAC package) and the Poisson-Boltzmann model (implemented in the APBS program). Different parameterizations of the molecules were examined: we compared MMFF94 force field, Amber12 force field and the quantum-chemical semi-empirical PM7 method implemented in the MOPAC package. For small molecules, all of the implicit solvent models tested here yield high correlation coefficients (0.87-0.93) between the calculated solvation energies and the experimental values of hydration energies. For small molecules high correlation (0.82-0.97) with the explicit solvent energies is seen as well. On the other hand, estimated protein solvation energies and protein-ligand binding desolvation energies show substantial discrepancy (up to 10kcal/mol) with the explicit solvent reference. The correlation of polar protein solvation energies and protein-ligand desolvation energies with the corresponding explicit solvent results is 0.65-0.99 and 0.76-0.96 respectively, though this difference in correlations is caused

  14. Theoretical study of solvent effects on the coil-globule transition

    Science.gov (United States)

    Polson, James M.; Opps, Sheldon B.; Abou Risk, Nicholas

    2009-06-01

    The coil-globule transition of a polymer in a solvent has been studied using Monte Carlo simulations of a single chain subject to intramolecular interactions as well as a solvent-mediated effective potential. This solvation potential was calculated using several different theoretical approaches for two simple polymer/solvent models, each employing hard-sphere chains and hard-sphere solvent particles as well as attractive square-well potentials between some interaction sites. For each model, collapse is driven by variation in a parameter which changes the energy mismatch between monomers and solvent particles. The solvation potentials were calculated using two fundamentally different methodologies, each designed to predict the conformational behavior of polymers in solution: (1) the polymer reference interaction site model (PRISM) theory and (2) a many-body solvation potential (MBSP) based on scaled particle theory introduced by Grayce [J. Chem. Phys. 106, 5171 (1997)]. For the PRISM calculations, two well-studied solvation monomer-monomer pair potentials were employed, each distinguished by the closure relation used in its derivation: (i) a hypernetted-chain (HNC)-type potential and (ii) a Percus-Yevick (PY)-type potential. The theoretical predictions were each compared to results obtained from explicit-solvent discontinuous molecular dynamics simulations on the same polymer/solvent model systems [J. Chem. Phys. 125, 194904 (2006)]. In each case, the variation in the coil-globule transition properties with solvent density is mostly qualitatively correct, though the quantitative agreement between the theory and prediction is typically poor. The HNC-type potential yields results that are more qualitatively consistent with simulation. The conformational behavior of the polymer upon collapse predicted by the MBSP approach is quantitatively correct for low and moderate solvent densities but is increasingly less accurate for higher densities. At high solvent densities

  15. Electron-Spin Filters Would Offer Spin Polarization Greater than 1

    Science.gov (United States)

    Ting, David Z.

    2009-01-01

    A proposal has been made to develop devices that would generate spin-polarized electron currents characterized by polarization ratios having magnitudes in excess of 1. Heretofore, such devices (denoted, variously, as spin injectors, spin polarizers, and spin filters) have typically offered polarization ratios having magnitudes in the approximate range of 0.01 to 0.1. The proposed devices could be useful as efficient sources of spin-polarized electron currents for research on spintronics and development of practical spintronic devices.

  16. 40 CFR Table 5 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... 63—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction... formulation data: Solvent type Averageorganic HAP mass fraction Typical organic HAP, percent by mass Aliphatic...

  17. Electrochemical behavior of uranyl in anhydrous polar organic media

    Energy Technology Data Exchange (ETDEWEB)

    Burn, Adam G.; Nash, Kenneth L. [Washington State Univ., Pullmann, WA (United States). Dept. of Chemistry

    2017-09-01

    Weak complexes between pentavalent and hexavalent actinyl cations have been reported to exist in acidic, non-complexing high ionic strength aqueous media. Such ''cation-cation complexes'' were first identified in the context of actinide-actinide redox reactions in acidic aqueous media relevant to solvent extraction-based separation systems, hence their characterization is of potential interest for advanced nuclear fuel reprocessing. This chemistry could be relevant to efforts to develop advanced actinide separations based on the upper oxidation states of americium, which are of current interest. In the present study, the chemical behavior of pentavalent uranyl was examined in non-aqueous, aprotic polar organic solvents (propylene carbonate and acetonitrile) to determine whether UO{sub 2}{sup +} cations generated at the reducing working electrode surface would interact with the UO{sub 2}{sup 2+} cations in the bulk phase to form cation-cation complexes in such media. In magnesium perchlorate media, the electrolyte adsorbed onto the working electrode surface and interfered with the uranyl reduction/diffusion process through an ECE (electron transfer/chemical reaction/electron transfer) mechanism. In parallel studies of uranyl redox behavior in tetrabutylammonium hexafluorophosphate solutions, an EC (electron transfer/chemical reaction) mechanism was observed in the cyclic voltammograms. Ultimately, no conclusive electrochemical evidence demonstrated uranyl cation-cation interactions in the non-aqueous, aprotic polar organic solvent solutions, though the results reported do not completely rule out the presence of UO{sub 2}{sup +}.UO{sub 2}{sup 2+} complexes.

  18. Enhanced fluidity liquid chromatography of inulin fructans using ternary solvent strength and selectivity gradients.

    Science.gov (United States)

    Bennett, Raffeal; Olesik, Susan V

    2018-01-25

    The value of exploring selectivity and solvent strength ternary gradients in enhanced fluidity liquid chromatography (EFLC) is demonstrated for the separation of inulin-type fructans from chicory. Commercial binary pump systems for supercritical fluid chromatography only allow for the implementation of ternary solvent strength gradients which can be restrictive for the separation of polar polymeric analytes. In this work, a custom system was designed to extend the capability of EFLC to allow tuning of selectivity or solvent strength in ternary gradients. Gradient profiles were evaluated using the Berridge function (RF 1 ), normalized resolution product (NRP), and gradient peak capacity (P c ). Selectivity gradients provided the separation of more analytes over time. The RF 1 function showed favor to selectivity gradients with comparable P c to that of solvent strength gradients. NRP did not strongly correlate with P c or RF 1 score. EFLC with the hydrophilic interaction chromatography, HILIC, separation mode was successfully employed to separate up to 47 fructan analytes in less than 25 min using a selectivity gradient. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Esterase Active in Polar Organic Solvents from the Yeast Pseudozyma sp. NII 08165

    Directory of Open Access Journals (Sweden)

    Deepthy Alex

    2014-01-01

    Full Text Available Esterases/lipases active in water miscible solvents are highly desired in biocatalysis where substrate solubility is limited and also when the solvent is desired as an acyl acceptor in transesterification reactions, as with the case of biodiesel production. We have isolated an esterase from the glycolipid producing yeast-Pseudozyma sp. NII 08165 which in its crude form was alkali active, thermo stable, halo tolerant and also capable of acting in presence of high methanol concentration. The crude enzyme which maintained 90% of its original activity after being treated at 70°C was purified and the properties were characterized. The partially purified esterase preparation had temperature and pH optima of 60°C and 8.0 respectively. The enzyme retained almost complete activity in presence of 25% methanol and 80% activity in the same strength of ethanol. Conditions of enzyme production were optimized, which lead to 9 fold increase in the esterase yield. One of the isoforms of the enzyme LIP1 was purified to homogeneity and characterized. Purified LIP1 had a Km and Vmax of 0.01 and 1.12, respectively. The purified esterase lost its thermo and halo tolerance but interestingly, retained 97% activity in methanol.

  20. Comparison of ambient solvent extraction methods for the analysis of fatty acids in non-starch lipids of flour and starch

    Science.gov (United States)

    Bahrami, Niloufar; Yonekura, Lina; Linforth, Robert; Carvalho da Silva, Margarida; Hill, Sandra; Penson, Simon; Chope, Gemma; Fisk, Ian Denis

    2014-01-01

    BACKGROUND Lipids are minor components of flours, but are major determinants of baking properties and end-product quality. To the best of our knowledge, there is no single solvent system currently known that efficiently extracts all non-starch lipids from all flours without the risk of chemical, mechanical or thermal damage. This paper compares nine ambient solvent systems (monophasic and biphasic) with varying polarities: Bligh and Dyer (BD); modified Bligh and Dyer using HCl (BDHCL); modified BD using NaCl (BDNaCl); methanol–chloroform–hexane (3:2:1, v/v); Hara and Radin (hexane–isopropanol, 3:2, v/v); water-saturated n-butanol; chloroform; methanol and hexane for their ability to extract total non-starch lipids (separated by lipid classes) from wheat flour (Triticum aestivum L.). Seven ambient extraction protocols were further compared for their ability to extract total non-starch lipids from three alternative samples: barley flour (Hordeum vulgare L.), maize starch (Zea mays L.) and tapioca starch (Manihot esculenta Crantz). RESULTS For wheat flour the original BD method and those containing HCl or NaCl tended to extract the maximum lipid and a significant correlation between lipid extraction yield (especially the glycolipids and phospholipids) and the polarity of the solvent was observed. For the wider range of samples BD and BD HCl repeatedly offered the maximum extraction yield and using pooled standardized (by sample) data from all flours, total non-starch lipid extraction yield was positively correlated with solvent polarity (r = 0.5682, P starches when compared to the flour samples, which is due to the differences in lipid profiles between the two sample types (flours and starches). PMID:24132804

  1. 40 CFR Table 4 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... Part 63—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction... formulation data. Solvent type Average organic HAP mass fraction Typical organic HAP, percent by mass...

  2. 40 CFR Table 4 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in the.... Solvent type Averageorganic HAP mass fraction Typical organic HAP, percent by mass Aliphatic b 0.03 1...

  3. 40 CFR Table 4 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in the... Solvent type Averageorganic HAP mass fraction Typical organic HAP, percent by mass Aliphatic b 0.03 1...

  4. Asphaltene self-association: Modeling and effect of fractionation with a polar solvent

    DEFF Research Database (Denmark)

    Garcia, Daniel Merino; Murgich, J; Andersen, Simon Ivar

    2004-01-01

    of DeltaH(a) obtained suggest that a fraction of asphaltenes is not active in the calorimetric experiments. Asphaltenes from Venezuela (LM1) and Mexico (KU) have been fractionated by precipitation with a mixture of acetone and toluene. It is considered that the most polar compounds are collected...

  5. Crystal Nucleation of Tolbutamide in Solution: Relationship to Solvent, Solute Conformation, and Solution Structure.

    Science.gov (United States)

    Zeglinski, Jacek; Kuhs, Manuel; Khamar, Dikshitkumar; Hegarty, Avril C; Devi, Renuka K; Rasmuson, Åke C

    2018-04-03

    The influence of the solvent in nucleation of tolbutamide, a medium-sized, flexible and polymorphic organic molecule, has been explored by measuring nucleation induction times, estimating solvent-solute interaction enthalpies using molecular modelling and calorimetric data, probing interactions and clustering with spectroscopy, and modelling solvent-dependence of molecular conformation in solution. The nucleation driving force required to reach the same induction time is strongly solvent-dependent, increasing in the order: acetonitrilenucleation difficulty is a function of the strength of solvent-solute interaction, with emphasis on the interaction with specific H-bonding polar sites of importance in the crystal structure. A clear exception from this rule is the most difficult nucleation in toluene despite the weakest solvent-solute interactions. However molecular dynamics modelling predicts that tolbutamide assumes an intramolecularly H-bonded conformation in toluene, substantially different from and more stable than the conformation in the crystal structure, and thus presenting an additional barrier to nucleation. This explains why nucleation in toluene is the most difficult and why the relatively higher propensity for aggregation of tolbutamide molecules in toluene solution, as observed with FTIR spectroscopy, does not translate into easier nucleation. Thus, our combined experimental and molecular modelling study suggests that the solvent can influence on the nucleation not only via differences in the desolvation but also through the influence on molecular conformation. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Steady State and Time-Resolved Fluorescence Dynamics of Triphenylamine Based Oligomers with Phenylene/Thiophene/Furan in Solvents

    International Nuclear Information System (INIS)

    Qi, Zeng; Ying-Liang, Liu; Kang, Meng; Xiang-Jie, Zhao; Shu-Feng, Wang; Qi-Huang, Gong

    2009-01-01

    We investigate the photo-physical properties of a series of triphenylamine-based oligomers by steady-state and picosecond transient fluorescence measurements in solvents. The oligomers are composed alternatively with triphenylamine and phenylene/thiophene/furan group, bridged by vinyl group (PNB/PNT/PNF). Their fluorescence spectra show bathochromic phenomenon with solvent polarity and viscosity increasing. The fluorescence decays are bi-exponential for PNB and PNT, and tri-exponential for PNF in THF and aniline. The strong viscosity dependence suggests conformational relaxation along the PNF chain after photo excitation. (condensed matter: electronicstructure, electrical, magnetic, and opticalproperties)

  7. Spin boson models for quantum decoherence of electronic excitations of biomolecules and quantum dots in a solvent

    International Nuclear Information System (INIS)

    Gilmore, Joel; McKenzie, Ross H

    2005-01-01

    We give a theoretical treatment of the interaction of electronic excitations (excitons) in biomolecules and quantum dots with the surrounding polar solvent. Significant quantum decoherence occurs due to the interaction of the electric dipole moment of the solute with the fluctuating electric dipole moments of the individual molecules in the solvent. We introduce spin boson models which could be used to describe the effects of decoherence on the quantum dynamics of biomolecules which undergo light-induced conformational change and on biomolecules or quantum dots which are coupled by Foerster resonant energy transfer

  8. Anti-solvent co-crystallization of carbamazepine and saccharin.

    Science.gov (United States)

    Wang, In-Chun; Lee, Min-Jeong; Sim, Sang-Jun; Kim, Woo-Sik; Chun, Nan-Hee; Choi, Guang J

    2013-06-25

    The co-crystal approach has been investigated extensively over the past decade as one of the most promising methods to enhance the dissolution properties of insoluble drug substances. Co-crystal powders are typically produced by mechanical grinding (neat or wet) or a solution method (evaporation or cooling). In this study, high-purity carbamazepine-saccharin (CBZ-SAC) co-crystals were manufactured by a novel method, anti-solvent addition. Among various solvents, methanol was found to perform well with water as the anti-solvent for the co-crystallization of CBZ and SAC. When water was added to the methanol solution of CBZ and SAC at room temperature under agitation, nucleation of CBZ-SAC co-crystals occurred within 2-3 min. Co-crystallization was complete after 30 min, giving a solid yield as high as 84.5% on a CBZ basis. The effects of initial concentrations, focusing on the SAC/CBZ ratio, were examined to establish optimal conditions. The whole anti-solvent co-crystallization process was monitored at-line via ATR-FTIR analysis of regularly sampled solutions. The nucleation and crystal growth of CBZ-SAC co-crystals were detected by a significant increase in absorption in the range of 2400-2260 cm(-1), associated with the formation of hydrogen bonds between the carbonyl group in CBZ and the N-H of SAC. When CBZ hydrates were formed as impurities during anti-solvent co-crystallization, the hydrogen bonding between methanol and water was reduced greatly, primarily due to the incorporation of water molecules into the CBZ crystal lattice. In conclusion, an anti-solvent approach can be used to produce highly pure CBZ-SAC co-crystal powders with a high solid yield. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Photo-physical and interactional behavior of two members of group B vitamins in different solvent media

    Science.gov (United States)

    Zakerhamidi, M. S.; Zare Haghighi, L.; Seyed Ahmadian, S. M.

    2017-09-01

    In this paper, absorption and fluorescence spectra of vitamin B12 (cyanocobalamin) and vitamin B6 (pyridoxine) were recorded in solvents with different polarity, at room temperature. These vitamins' photo-physical behavior depends strongly on the solvent's nature along with different attached groups in their structures. In order to investigate the solvent-solute interactions and environmental effect on spectral variations, linear solvation energy relationships concept, suggested by Kamlet and Taft was used. Solvatochromic method was also used for measuring the ground and excited state dipole moments of these vitamins. According to our experimental results, dipole moment of these groups of vitamins in excited state is larger than ground state. Furthermore, obtained photo-physical and interactional properties of used vitamins can give important information on how this group of vitamins behaves in biological systems.

  10. Natural deep eutectic solvents (NADES) as green solvents for carbon dioxide capture

    Science.gov (United States)

    Mulia, Kamarza; Putri, Sylvania; Krisanti, Elsa; Nasruddin

    2017-03-01

    This study was conducted to determine the effectiveness of Natural Deep Eutectic Solvent (NADES), consisting of choline chloride and a hydrogen bonding donor (HBD) compound, in terms of carbon dioxide absorption. Solubility of carbon dioxide in NADES was found to be influenced HBD compound used and choline chloride to HBD ratio, carbon dioxide pressure, and contact time. HBD and choline/HBD ratios used were 1,2-propanediol (1:2), glycerol (1:2), and malic acid (1:1). The carbon dioxide absorption measurement was conducted using an apparatus that utilizes the volumetric method. Absorption curves were obtained up to pressures of 30 bar, showing a linear relationship between the amount absorbed and the final pressure of carbon dioxide. The choline and 1,2-propanediol eutectic mixture absorbs the highest amount of carbon dioxide, approaching 0.1 mole-fraction at 3.0 MPa and 50°C. We found that NADES ability to absorb carbon dioxide correlates with its polarity as tested using Nile Red as a solvatochromic probe.

  11. Broadband polarized emission from P(NDI2OD-T2) polymer.

    Science.gov (United States)

    Ulrich, Steve; Sutch, Tabitha; Szulczewski, Greg; Schweizer, Matthias; Barbosa, Newton; Araujo, Paulo

    2018-05-18

    We investigate the P(NDI2OD-T2) photophysical properties via absorbance and fluorescence spectroscopy, in association with the experimental approach baptized Stokes Spectroscopy, which provides valuable material information through the acquisition and analysis of the fluorescence polarization degree. By changing solvents and using different samples such as solutions, thick, and thin films, it is possible to control the polarization degree spectrum associated to the fluorescence emitted by the polymer's isolated chains and aggregates. We show that the polarization degree could become a powerful tool to obtain information related to the samples morphology, which is connected to their microscopic structure. Moreover, the polarization degree spectra suggest that depolarization effects linked to energy and charge transfer mechanisms are likely taking place. Our findings indicate that P(NDI2OD-T2) polymers are excellent candidates for the advancement of organic technologies that rely on the emission and detection of polarized lights. © 2018 IOP Publishing Ltd.

  12. Polar Diels-Alder reactions using electrophilic nitrobenzothiophenes. A combined experimental and DFT study

    Science.gov (United States)

    Della Rosa, Claudia D.; Mancini, Pedro M. E.; Kneeteman, Maria N.; Lopez Baena, Anna F.; Suligoy, Melisa A.; Domingo, Luis R.

    2015-01-01

    The reactions between 2- and 3-nitrobenzothiophenes with three dienes of different nucleophilicity, 1-methoxy-3-trimethylsilyloxy-1,3-butadiene, 1-trimethylsilyloxy-1,3-butadiene and isoprene developed in anhydrous benzene and alternative under microwave irradiation with molecular solvents or in free solvent conditions, respectively, for produce dibenzothiophenes permit to conclude that both nitroheterocycles act as electrophile with the cited dienes. In the cases of the dienes 1-methoxy-3-trimethylsilyloxy-1,3-butadiene and 1-trimethylsilyloxy-1,3-butadiene which posses major nucleophilicity the observed product is the normal cycloaddition one. However when the diene is isoprene the product with both electrophiles follow the hetero Diels-Alder way. These reactions are considered polar cycloaddition reactions and the yields are reasonables. Moreover the polar Diels-Alder reactions of nitrobenzothiophenes with electron rich dienes 1-trimethylsilyloxy-1,3-butadiene have been theoretically studied using DFT methods.

  13. SFC-MS/MS as an orthogonal technique for improved screening of polar analytes in anti-doping control.

    Science.gov (United States)

    Parr, Maria Kristina; Wuest, Bernhard; Naegele, Edgar; Joseph, Jan F; Wenzel, Maxi; Schmidt, Alexander H; Stanic, Mijo; de la Torre, Xavier; Botrè, Francesco

    2016-09-01

    HPLC is considered the method of choice for the separation of various classes of drugs. However, some analytes are still challenging as HPLC shows limited resolution capabilities for highly polar analytes as they interact insufficiently on conventional reversed-phase (RP) columns. Especially in combination with mass spectrometric detection, limitations apply for alterations of stationary phases. Some highly polar sympathomimetic drugs and their metabolites showed almost no retention on different RP columns. Their retention remains poor even on phenylhexyl phases that show different selectivity due to π-π interactions. Supercritical fluid chromatography (SFC) as an orthogonal separation technique to HPLC may help to overcome these issues. Selected polar drugs and metabolites were analyzed utilizing SFC separation. All compounds showed sharp peaks and good retention even for the very polar analytes, such as sulfoconjugates. Retention times and elution orders in SFC are different to both RP and HILIC separations as a result of the orthogonality. Short cycle times could be realized. As temperature and pressure strongly influence the polarity of supercritical fluids, precise regulation of temperature and backpressure is required for the stability of the retention times. As CO2 is the main constituent of the mobile phase in SFC, solvent consumption and solvent waste are considerably reduced. Graphical Abstract SFC-MS/MS vs. LC-MS/MS.

  14. The Polarization of Achernar

    Science.gov (United States)

    McDavid, D.

    2005-11-01

    Recent near-infrared measurements of the angular diameter of Achernar (the bright Be star alpha Eridani) with the ESO VLT interferometer have been interpreted as the detection of an extremely oblate photosphere, with a ratio of equatorial to polar radius of at least 1.56 ± 0.05 and a minor axis orientation of 39° ± 1° (from North to East). The optical linear polarization of this star during an emission phase in 1995 September was 0.12 ± 0.02% at position angle 37° ± 8° (in equatorial coordinates), which is the direction of the projection of the rotation axis on the plane of the sky according to the theory of polarization by electron scattering in an equatorially flattened circumstellar disk. These two independent determinations of the orientation of the rotation axis are therefore in agreement. The observational history of correlations between Hα emission and polarization as found in the literature is that of a typical Be star, with the exception of an interesting question raised by the contrast between Schröder's measurement of a small polarization perpendicular to the projected rotation axis in 1969--70 and Tinbergen's measurement of zero polarization in 1974.5, both at times when emission was reportedly absent.

  15. Competitive photocyclization/rearrangement of 4-aryl-1,1-dicyanobutenes controlled by intramolecular charge-transfer interaction. Effect of medium polarity, temperature, pressure, excitation wavelength, and confinement.

    Science.gov (United States)

    Ito, Tadashi; Nishiuchi, Emi; Fukuhara, Gaku; Inoue, Yoshihisa; Mori, Tadashi

    2011-09-01

    A series of 4-aryl-1,1-dicyanobutenes (1a-1f) with different substituents were synthesized to control the intramolecular donor-acceptor or charge-transfer (C-T) interactions in the ground state. Photoexcitation of these C-T substrates led to competitive cyclization and rearrangement, the ratio being critically controlled by various environmental factors, such as solvent polarity, temperature and static pressure, and also by excitation wavelength and supramolecular confinement (polyethylene voids). In non-polar solvents, the rearrangement was dominant (>10 : 1) for all examined substrates, while the cyclization was favoured in polar solvents, in particular at low temperatures. Selective excitation at the C-T band further enhanced the cyclization up to >50 : 1 ratios. More importantly, the cyclization/rearrangement ratio was revealed to be a linear function of the C-T transition energy. However, the substrates with a sterically demanding or highly electron-donating substituent failed to give the cyclization product.

  16. Nanospikes functionalization as a universal strategy to disperse hydrophilic particles in non-polar media

    Science.gov (United States)

    Hang, Tian; Chen, Hui-Jiuan; Wang, Ji; Lin, Di-an; Wu, Jiangming; Liu, Di; Cao, Yuhong; Yang, Chengduan; Liu, Chenglin; Xiao, Shuai; Gu, Meilin; Pan, Shuolin; Wu, Mei X.; Xie, Xi

    2018-05-01

    Dispersion of hydrophilic particles in non-polar media has many important applications yet remains difficult. Surfactant or amphiphilic functionalization was conventionally applied to disperse particles but is highly dependent on the particle/solvent system and may induce unfavorable effects and impact particle hydrophilic nature. Recently 2 μm size polystyrene microbeads coated with ZnO nanospikes have been reported to display anomalous dispersity in phobic media without using surfactant or amphiphilic functionalization. However, due to the lack of understanding whether this phenomenon was applicable to a wider range of conditions, little application has been derived from it. Here the anomalous dispersity phenomenons of hydrophilic microparticles covered with nanospikes were systematically assessed at various conditions including different particle sizes, material compositions, particle morphologies, solvent hydrophobicities, and surface polar groups. Microparticles were functionalized with nanospikes through hydrothermal route, followed by dispersity test in hydrophobic media. The results suggest nanospikes consistently prevent particle aggregation in various particle or solvent conditions, indicating the universal applicability of the anomalous dispersion phenomenons. This work provides insight on the anomalous dispersity of hydrophilic particles in various systems and offers potential application to use this method for surfactant-free dispersions.

  17. Cyclodextrin Films with Fast Solvent Transport and Shape-Selective Permeability

    KAUST Repository

    Villalobos, Luis Francisco

    2017-04-24

    This study describes the molecular-level design of a new type of filtration membrane made of crosslinked cyclodextrins-inexpensive macrocycles of glucose, shaped like hollow truncated cones. The channel-like cavities of cyclodextrins spawn numerous paths of defined aperture in the separation layer that can effectively discriminate between molecules. The transport of molecules through these membranes is highly shape-sensitive. In addition, the presence of hydrophobic (cavity) and hydrophilic (ester-crosslinked outer part) domains in these films results in high permeances for both polar and nonpolar solvents.

  18. Apparatus and methods for regeneration of precipitating solvent

    Science.gov (United States)

    Liu, Guohai; Vimalchand, Pannalal; Peng, Wan Wang; Bonsu, Alexander

    2015-08-25

    A regenerator that can handle rich loaded chemical solvent containing precipitated absorption reaction products is disclosed. The invention is particularly suitable for separating CO.sub.2 from large gas streams that are typical of power plant processes. The internally circulating liquid stream in the regenerator (ICLS regenerator) rapidly heats-up the in-coming rich solvent stream in a downcomer standpipe as well as decreases the overall concentration of CO.sub.2 in the mixed stream. Both these actions lead to dissolution of precipitates. Any remaining precipitate further dissolves as heat is transferred to the mixed solution with an inverted bayonet tube heat exchanger in the riser portion of the regenerator. The evolving CO.sub.2 bubbles in the riser portion of the regenerator lead to substantial gas hold-up and the large density difference between the solutions in the downcomer standpipe and riser portions promotes internal circulation of the liquid stream in the regenerator. As minor amounts of solvent components present in the exit gas stream are condensed and returned back to the regenerator, pure CO.sub.2 gas stream exits the disclosed regenerator and condenser system.

  19. Effect of reaction solvent on hydroxyapatite synthesis in sol-gel process

    Science.gov (United States)

    Nazeer, Muhammad Anwaar; Yilgor, Emel; Yagci, Mustafa Baris; Unal, Ugur; Yilgor, Iskender

    2017-12-01

    Synthesis of hydroxyapatite (HA) through sol-gel process in different solvent systems is reported. Calcium nitrate tetrahydrate (CNTH) and diammonium hydrogen phosphate (DAHP) were used as calcium and phosphorus precursors, respectively. Three different synthesis reactions were carried out by changing the solvent media, while keeping all other process parameters constant. A measure of 0.5 M aqueous DAHP solution was used in all reactions while CNTH was dissolved in distilled water, tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) at a concentration of 0.5 M. Ammonia solution (28-30%) was used to maintain the pH of the reaction mixtures in the 10-12 range. All reactions were carried out at 40 ± 2°C for 4 h. Upon completion of the reactions, products were filtered, washed and calcined at 500°C for 2 h. It was clearly demonstrated through various techniques that the dielectric constant and polarity of the solvent mixture strongly influence the chemical structure and morphological properties of calcium phosphate synthesized. Water-based reaction medium, with highest dielectric constant, mainly produced β-calcium pyrophosphate (β-CPF) with a minor amount of HA. DMF/water system yielded HA as the major phase with a very minor amount of β-CPF. THF/water solvent system with the lowest dielectric constant resulted in the formation of pure HA.

  20. Theoretical and experimental study of the relaxation of excited states of the DCM laser dye. Intra-molecular electron transfer and photo-isomerization. Solvent effects

    International Nuclear Information System (INIS)

    Marguet, Sylvie

    1992-01-01

    This research thesis reports the study of a styrenic laser dye, the 4-(dicyanomethylene)-2-methyl-6-[p-(dimethylamino) styryl]-4H-pyrane or DCM for the characterization of the first electronic states and of the influence of the solvent on efficiencies of different relaxation processes of the first excited state S1 of the DCM. Due to the presence of a combination of a donor group and acceptor group, this compound has interesting properties of intra-molecular charge transfer and of photo-isomerization which highly depend on solvent polarity. Two approaches have been adopted to study these complementary processes: an experimental approach (determination of rate constants of the different deactivation ways of the S1 state by measuring fluorescence quantum efficiencies, photo-isomerization quantum efficiencies, and fluorescence lifetimes of DCM in about twenty solvent of increasing polarity), and a computational approach (a CS-INDO-MRI type quantum chemistry calculation to obtain potential energy curves, charge distributions, and dipolar moments of DCM first electronic states) [fr

  1. Response behavior of an epoxy resin/amine curing agent/carbon black composite film to various solvents

    Energy Technology Data Exchange (ETDEWEB)

    Luo Yanling [School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China)]. E-mail: luoyl0401@yahoo.com.cn; Li Zhanqing [School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China); Lan Wenxiang [School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China)

    2007-04-25

    A novel polymer based sensitive film was prepared from thermosetting epoxy resins (EP) filled with carbon blacks. The curing reaction of amine curing agents with epoxy resins and the response of the curing resultants to solvent vapors were dealt with. The influence of the types and content of carbon blacks and curing agents, and curing temperatures and time on curing reactions and response selectivity of the conductive films were investigated. The structural characterization was conducted on a Fourier transform infrared spectrophotometer (FTIR). The results indicated that the conductive films showed high response selectivity to polar solvent vapors, especially to chloroform vapor, while no response was observed in non-polar solvent vapors. The responsivity of the film increased with the decreased carbon black contents. The film filled with acetylene carbon black gave an optimal response, with responsivity of about 700 times. The response performances were improved with the amount of curing agents increased, and an optimal response appeared at the amount of the curing agent of 8%. The film's responsivity was remarkably enhanced, the reversibility property, however, rapidly declined in the order of diethyleneltriamine < triethylenetetramine < ethylenediamine. The curing reaction tended to complete with the curing temperature elevated and the curing time prolonged. But the response performance dropped because of over cross-linking as the temperature was too high or the time was too long.

  2. Response behavior of an epoxy resin/amine curing agent/carbon black composite film to various solvents

    International Nuclear Information System (INIS)

    Luo Yanling; Li Zhanqing; Lan Wenxiang

    2007-01-01

    A novel polymer based sensitive film was prepared from thermosetting epoxy resins (EP) filled with carbon blacks. The curing reaction of amine curing agents with epoxy resins and the response of the curing resultants to solvent vapors were dealt with. The influence of the types and content of carbon blacks and curing agents, and curing temperatures and time on curing reactions and response selectivity of the conductive films were investigated. The structural characterization was conducted on a Fourier transform infrared spectrophotometer (FTIR). The results indicated that the conductive films showed high response selectivity to polar solvent vapors, especially to chloroform vapor, while no response was observed in non-polar solvent vapors. The responsivity of the film increased with the decreased carbon black contents. The film filled with acetylene carbon black gave an optimal response, with responsivity of about 700 times. The response performances were improved with the amount of curing agents increased, and an optimal response appeared at the amount of the curing agent of 8%. The film's responsivity was remarkably enhanced, the reversibility property, however, rapidly declined in the order of diethyleneltriamine < triethylenetetramine < ethylenediamine. The curing reaction tended to complete with the curing temperature elevated and the curing time prolonged. But the response performance dropped because of over cross-linking as the temperature was too high or the time was too long

  3. Parâmetros reacionais para a síntese enzimática do butirato de butila em solventes orgânicos Reactional parameters for enzymatic synthesis of butyl butyrate in organic solvent

    Directory of Open Access Journals (Sweden)

    Heizir F. CASTRO

    1997-12-01

    Full Text Available A síntese orgânica catalisada por enzimas envolve um mecanismo complexo dependente do tipo de substrato, enzima, solvente orgânico e teor de água no meio reacional. Neste trabalho foi estudado a influência de alguns desses parâmetros no rendimento da esterificação do butanol com ácido butírico, utilizando uma preparação enzimática comercial de lipase. A polaridade e natureza do solvente, bem como a razão molar entre o butanol e ácido butírico, foram considerados os fatores que mais influenciaram o desenvolvimento dessa síntese enzimática.The organic synthesis catalyzed by enzymes is a complex function of substrate concentration, water concentration in the liquid phase, enzyme and organic solvent properties. In this work the influence of some parameters on the esterification of butanol with butyric acid was investigated, using a commercial lipase preparation. The polarity and nature of the solvent and also the substrate mole ratios played an important role in the performance of this enzymatic synthesis.

  4. Modifying Poisson equation for near-solute dielectric polarization and solvation free energy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Pei-Kun, E-mail: peikun@isu.edu.tw

    2016-06-15

    Highlights: • We modify the Poisson equation. • The dielectric polarization was calculated from the modified Poisson equation. • The solvation free energies of the solutes were calculated from the dielectric polarization. • The calculated solvation free energies were similar to those obtained from MD simulations. - Abstract: The dielectric polarization P is important for calculating the stability of protein conformation and the binding affinity of protein–protein/ligand interactions and for exploring the nonthermal effect of an external electric field on biomolecules. P was decomposed into the product of the electric dipole moment per molecule p; bulk solvent density N{sub bulk}; and relative solvent molecular density g. For a molecular solute, 4πr{sup 2}p(r) oscillates with the distance r to the solute, and g(r) has a large peak in the near-solute region, as observed in molecular dynamics (MD) simulations. Herein, the Poisson equation was modified for computing p based on the modified Gauss’s law of Maxwell’s equations, and the potential of the mean force was used for computing g. For one or two charged atoms in a water cluster, the solvation free energies of the solutes obtained by these equations were similar to those obtained from MD simulations.

  5. Testing proton spin models with polarized beams

    International Nuclear Information System (INIS)

    Ramsey, G.P.

    1991-01-01

    We review models for spin-weighted parton distributions in a proton. Sum rules involving the nonsinglet components of the structure function xg 1 p help narrow the range of parameters in these models. The contribution of the γ 5 anomaly term depends on the size of the integrated polarized gluon distribution and experimental predictions depend on its size. We have proposed three models for the polarized gluon distributions, whose range is considerable. These model distributions give an overall range is considerable. These model distributions give an overall range of parameters that can be tested with polarized beam experiments. These are discussed with regard to specific predictions for polarized beam experiments at energies typical of UNK

  6. Preferential solvation and solvation shell composition of free base and protonated 5, 10, 15, 20-tetrakis(4-sulfonatophenyl)porphyrin in aqueous organic mixed solvents

    Science.gov (United States)

    Farajtabar, Ali; Jaberi, Fatemeh; Gharib, Farrokh

    2011-12-01

    The solvatochromic properties of the free base and the protonated 5, 10, 15, 20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) were studied in pure water, methanol, ethanol (protic solvents), dimethylsulfoxide, DMSO, (non-protic solvent), and their corresponding aqueous-organic binary mixed solvents. The correlation of the empirical solvent polarity scale ( ET) values of TPPS with composition of the solvents was analyzed by the solvent exchange model of Bosch and Roses to clarify the preferential solvation of the probe dyes in the binary mixed solvents. The solvation shell composition and the synergistic effects in preferential solvation of the solute dyes were investigated in terms of both solvent-solvent and solute-solvent interactions and also, the local mole fraction of each solvent composition was calculated in cybotactic region of the probe. The effective mole fraction variation may provide significant physico-chemical insights in the microscopic and molecular level of interactions between TPPS species and the solvent components and therefore, can be used to interpret the solvent effect on kinetics and thermodynamics of TPPS. The obtained results from the preferential solvation and solvent-solvent interactions have been successfully applied to explain the variation of equilibrium behavior of protonation of TPPS occurring in aqueous organic mixed solvents of methanol, ethanol and DMSO.

  7. Solvent extraction of Zn and metals in Zn ores by nonphosphorous solvents

    International Nuclear Information System (INIS)

    Auchapt, J.M.; Tostain, Jacqueline.

    1975-07-01

    This bibliography follows a first work on Zn solvent extraction by organo-phosphorous compounds. The other solvents used in Zn extraction, are studied: oxygenated nonphosphorous solvents (ketones, alcohols, carboxylic acids, sulfonates), nitrogenous solvents and hydrocarbons [fr

  8. Potentiometric investigations of (acid+base) equilibria in (n-butylamine+acetic acid) systems in binary (acetone+cyclohexane) solvent mixtures

    International Nuclear Information System (INIS)

    Czaja, MaIgorzata; Kozak, Anna; Makowski, Mariusz; Chmurzynski, Lech

    2005-01-01

    By using the potentiometric titration method, standard equilibrium constants have been determined of acid dissociation of molecular acid, K a (HA), cationic acid, K a (BH + ), of anionic and cationic homoconjugation, K AHA - andK BHB + , respectively, and of molecular heteroconjugation, K AHB (K BHA ), in (acid+base) systems without proton transfer consisting of n-butylamine and acetic acid in binary (acetone+cyclohexane) solvent mixtures. The results have shown that both the pK a (HA) and pK a (BH + ), as well as lgK AHA - values change non-linearly as a function of composition of the solvent mixture. On the other hand, standard molecular heteroconjugation constants without proton transfer do not depend on the cyclohexane content in the mixture, i.e. on solvent polarity

  9. Dust in the small Magellanic cloud. 1: Interstellar polarization and extinction data

    Science.gov (United States)

    Magalhaes, A. M.; Rodrigues, C. V.; Coyne, C. V.; Piirola, V.

    1996-01-01

    The typical extinction curve for the Small Magellanic Cloud (SMC), in contrast to that for the Galaxy, has no bump at 2175 A and has a steeper rise into the far ultraviolet. For the Galaxy the interpretation of the extinction and, therefore, the dust content of the interstellar medium has been greatly assisted by measurements of the wavelength dependence of the polarization. For the SMC no such measurements existed. Therefore, to further elucidate the dust properties in the SMC we have for the first time measured linear polarization with five colors in the optical region of the spectrum for a sample of reddened stars. For two of these stars, for which there were no existing UV spectrophotometric measurements, but for which we measured a relatively large polarization, we have also obtained data from the International Ultraviolet Explorer (IUE) in order to study the extinction. We also attempt to correlate the SMC extinction and polarization data. The main results are: the wavelength of maximum polarization, lambda(sub max), in the SMC is typically smaller than that in the Galaxy; however, AZC 456, which shows the UV extinction bump, has a lambda(sub max) typical of that in the Galaxy, but its polarization curve is narrower and its bump is shifted to shorter wavelengths as compared to the Galaxy; and from an analysis of both the extinction and polarization data it appears that the SMC has typically smaller grains than those in the Galaxy. The absence of the extinction bump in the SMC has generally been thought to imply a lower carbon abundance in the SMC compared to the Galaxy. We interpret our results to mean that te size distribution of the interstellar grains, and not only the carbon abundance, is different in the SMC as compared to the Galaxy. In Paper 2 we present dust model fits to these observations.

  10. Solvent substitution

    International Nuclear Information System (INIS)

    1990-01-01

    The DOE Environmental Restoration and Waste Management Office of Technology Development and the Air Force Engineering and Services Center convened the First Annual International Workshop on Solvent Substitution on December 4--7, 1990. The primary objectives of this joint effort were to share information and ideas among attendees in order to enhance the development and implementation of required new technologies for the elimination of pollutants associated with industrial use of hazardous and toxic solvents; and to aid in accelerating collaborative efforts and technology transfer between government and industry for solvent substitution. There were workshop sessions focusing on Alternative Technologies, Alternative Solvents, Recovery/Recycling, Low VOC Materials and Treatment for Environmentally Safe Disposal. The 35 invited papers presented covered a wide range of solvent substitution activities including: hardware and weapons production and maintenance, paint stripping, coating applications, printed circuit boards, metal cleaning, metal finishing, manufacturing, compliance monitoring and process control monitoring. This publication includes the majority of these presentations. In addition, in order to further facilitate information exchange and technology transfer, the US Air Force and DOE solicited additional papers under a general ''Call for Papers.'' These papers, which underwent review and final selection by a peer review committee, are also included in this combined Proceedings/Compendium. For those involved in handling, using or managing hazardous and toxic solvents, this document should prove to be a valuable resource, providing the most up-to-date information on current technologies and practices in solvent substitution. Individual papers are abstracted separated

  11. Optimization of co-solvent addition in supercritical fluid extraction of fat with carbon dioxide

    Directory of Open Access Journals (Sweden)

    Ivanov Dušica S.

    2011-01-01

    Full Text Available This investigation is concerned with supercritical fluid extraction (SFE using CO2, as an analytical technique for total fat extraction from food and feed samples. Its most significant advantages are safety, cleanness, and shorter extraction time. The main limitation of this technique includes the difficulty of extracting polar lipids due to the non-polar character of the solvent (CO2 used for the extraction. The influence of ethanol as a co-solvent on the SFE of mash pig feed was investigated in this paper. Total fat content was determined by SFE and Soxhlet method for ten commercially available mesh pig feeds. Yields of the fat extracted by both methods were plotted one against the other and compared. Statistically significant difference (p ≤ 0.05 has been found only between the total fat obtained by the Soxhlet extraction and SFE by pure CO2. Based on the mathematical model, maximum yield of the extracted fat is achieved at an ethanol addition of 0.67 ml/g of sample, when the other parameters are the same as recommended by the producer’s procedure.

  12. Determination of water traces in various organic solvents using Karl Fischer method under FIA conditions.

    Science.gov (United States)

    Dantan, N; Frenzel, W; Küppers, S

    2000-05-31

    Flow injection methods utilising the Karl Fischer (KF) reaction with spectrophotometric and potentiometric detection are described for the determination of the trace water content in various organic solvents. Optimisation of the methods resulted in an accessible (linear) working range of 0.01-0.2% water for many solvents studied with a typical precision of 1-2% R.S.D. Only 50 mul of organic solvent was injected and the sampling frequency was about 120 samples per h. Since the slopes of the calibration curves were different for different solvents appropriate calibration was required. Problems associated with spectrophotometric detection and caused by refractive index changes were pointed out and a nested-loop configuration was proposed to overcome this kind of interference. The potentiometric method with a novel flow-through detector cell was shown to surpass the performance of spectrophotometric detection in any respect. The characteristics of the procedures developed made them well applicable for on-line monitoring of technical solvent distillations in an industrial plant.

  13. Solvent effects on ion-receptor interactions in the presence of an external electric field.

    Science.gov (United States)

    Novák, Martin; Foroutan-Nejad, Cina; Marek, Radek

    2016-11-09

    In this work we investigated the influence of an external electric field on the arrangement of the solvent shells around ions interacting with a carbon-based receptor. Our survey reveals that the mechanism of interaction between a monoatomic ion and a π-type ion receptor varies by the variation in the solvent polarity, the nature of the ion, and the strength of the external field. The characteristics of the ion-surface interaction in nonpolar solvents are similar to those observed in a vacuum. However, in water, we identified two mechanisms. Soft and polarizable ions preferentially interact with the π-receptor. In contrast, two bonded states were found for hard ions. A fully solvated ion, weakly interacting with the receptor at weak field, and a strong π-complex at the strong-field regime were identified. An abrupt variation in the potential energy surface (PES) associated with the rearrangement of the solvation shell on the surface of the receptor induced by an external field was observed both in implicit and explicit solvent environments. The electric field at which the solvation shell breaks is proportional to the hardness of the ion as has been suggested recently based on experimental observations.

  14. Electric Dipole Transition Moments and Solvent-Dependent Interactions of Fluorescent Boron-Nitrogen Substituted Indole Derivatives.

    Science.gov (United States)

    Saif, Mari; Widom, Julia R; Xu, Senmiao; Abbey, Eric R; Liu, Shih-Yuan; Marcus, Andrew H

    2015-06-25

    Fluorescent analogues of the indole side chain of tryptophan can be useful spectroscopic probes of protein-protein and protein-DNA interactions. Here we present linear dichroism and solvent-dependent spectroscopic studies of two fluorescent analogues of indole, in which the organic C═C unit is substituted with the isosteric inorganic B-N unit. We studied the so-called "external" BN indole, which has C2v symmetry, and the "fused" BN indole with Cs symmetry. We performed a combination of absorption and fluorescence spectroscopy, ultraviolet linear dichroism (UV-LD) in stretched poly(ethylene) (PE) films, and quantum chemical calculations on both BN indole compounds. Our measurements allowed us to characterize the degree of alignment for both molecules in stretched PE films. We thus determined the orientations and magnitudes of the two lowest energy electric dipole transition moments (EDTMs) for external BN indole, and the two lowest energy EDTMs for fused BN indole within the 30 000-45 000 cm(-1) spectral range. We compared our experimental results to those of quantum chemical calculations using standard density functional theory (DFT). Our theoretical predictions for the low-energy EDTMs are in good agreement with our experimental data. The absorption and fluorescence spectra of the external and the fused BN indoles are sensitive to solvent polarity. Our results indicate that the fused BN indole experiences much greater solvation interactions with polar solvents than does the external BN indole.

  15. Purification and characterization of an extracellular halophilic and organic solvent-tolerant amylopullulanase from a haloarchaeon, Halorubrum sp. strain Ha25.

    Directory of Open Access Journals (Sweden)

    Mostafa Fazeli

    2013-01-01

    Full Text Available Introduction: Halophiles, especially haloarchaea are one of the most important groups of extremophiles. Halophilic hydrolases have been studied worldwide and have been considered for biotechnology and industrial technologies. This study is the first report in amylopullulanase production in halophilic microorganisms.Materials and methods: A halophilic archaeon, Halorubrum sp. strain Ha25, produced extracellular halophilic organic solvent-tolerant amylopullulanase. The enzyme was purified using ethanol precipitation and anion exchange chromatography method. Molecular mass of purified enzyme was determined by SDS–PAGE method. After purification, the enzyme was characterized. To study the effects of organic solvents in the stability of the enzyme, the enzyme solution was incubated in the presence of various organic compounds and then, residual enzyme activity was measured. Mode of action of the enzyme was determined by thin-layer chromatography.Results: Molecular weight of the purified enzyme was estimated to be 140 kDa by SDS–PAGE method. Optimum temperature for amylolitic and pullulytic activities was 50 °C. Optimum pH for amylolitic activity was 7.0 and for pullulytic activity was 7.5. This enzyme was active over a wide range of concentrations (0-4.5 M of NaCl. The effect of organic solvents on the amylolitic and pullulytic activities showed that this enzyme was more stable in the presence of non-polar organic solvents than polar solvents. The enzyme solely hydrolyzed pullulan and soluble starch to glucose.Discussion and conclusion: Halorubrum sp. strain Ha25 produces thermophilic and extremely halophilic amylopullulanase. The catalytic function under multi extreme condition of high temperature, high salinity, and low water activity might possess biotechnological and commercial values such as treatment waste solutions with starch residues, high salt content and solvents.

  16. Characteristics and antioxidant of Ulva intestinalis sulphated polysaccharides extracted with different solvents.

    Science.gov (United States)

    Peasura, Napassorn; Laohakunjit, Natta; Kerdchoechuen, Orapin; Wanlapa, Sorada

    2015-11-01

    Ulva intestinalis, a tubular green seaweed, is a rich source of nutrient, especially sulphated polysaccharides. Sulphated polysaccharides from U. intestinalis were extracted with distilled water, 0.1N HCl, and 0.1N NaOH at 80°C for 1, 3, 6, 12, and 24h to study the effect of the extraction solvent and time on their chemical composition and antioxidant activity. Different types of solvents and extraction time had a significant influence on the chemical characteristics and antioxidant activity (pMonosaccharide composition and FT-IR spectra analyses revealed that sulphated polysaccharides from all solvent extractions have a typical sugar backbone (glucose, rhamnose, and sulphate attached at C-2 or C-3 of rhamnose). Sulphated polysaccharides extracted with acid exhibited greater antioxidant activity than did those extracted with distilled water and alkali. The results indicated that solvent extraction could be an efficacious method for enhancing antioxidant activity by distinct molecular weight and chemical characteristic of sulphated polysaccharides. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Determination of solvents permeating through chemical protective clothing with a microsensor array.

    Science.gov (United States)

    Park, J; Zellers, E T

    2000-08-01

    The performance of a novel prototype instrument in determining solvents and solvent mixtures permeating through samples of chemical protective clothing (CPC) materials was evaluated. The instrument contains a mini-preconcentrator and an array of three polymer-coated surface-acoustic-wave (SAW) microsensors whose collective response patterns are used to discriminate among multiple permeants. Permeation tests were performed with a 2.54 cm diameter test cell in an open-loop configuration on samples of common glove materials challenged with four individual solvents, three binary mixtures, and two ternary mixtures. Breakthrough times, defined as the times required for the permeation rate to reach a value of 1 microg cm(-2) min(-1), determined by the instrument were within 3 min of those determined in parallel by manual sampling and gas chromatographic analysis. Permeating solvents were recognized (identified) from their response patterns in 59 out of 64 measurements (92%) and their vapor concentrations were quantified to an accuracy of +/- 31% (typically +/- 10%). These results demonstrate the potential for such instrumentation to provide semi-automated field or bench-top screening of CPC permeation resistance.

  18. Dissolution Dynamic Nuclear Polarization capability study with fluid path

    DEFF Research Database (Denmark)

    Malinowski, Ronja Maja; Lipsø, Hans Kasper Wigh; Lerche, Mathilde Hauge

    2016-01-01

    Signal enhancement by hyperpolarization is a way of overcoming the low sensitivity in magnetic resonance; MRI in particular. One of the most well-known methods, dissolution Dynamic Nuclear Polarization, has been used clinically in cancer patients. One way of ensuring a low bioburden of the hyperp......Signal enhancement by hyperpolarization is a way of overcoming the low sensitivity in magnetic resonance; MRI in particular. One of the most well-known methods, dissolution Dynamic Nuclear Polarization, has been used clinically in cancer patients. One way of ensuring a low bioburden...... of the hyperpolarized product is by use of a closed fluid path that constitutes a barrier to contamination. The fluid path can be filled with the pharmaceuticals, i.e. imaging agent and solvents, in a clean room, and then stored or immediately used at the polarizer. In this study, we present a method of filling...

  19. Do embryonic polar bodies commit suicide?

    Science.gov (United States)

    Fabian, Dušan; Čikoš, Štefan; Rehák, Pavol; Koppel, Juraj

    2014-02-01

    The extrusion and elimination of unnecessary gametic/embryonic material is one of the key events that determines the success of further development in all living organisms. Oocytes produce the first polar body to fulfill the maturation process just before ovulation, and release the second polar body immediately after fertilization. The aim of this study was to compile a physiological overview of elimination of polar bodies during early preimplantation development in mice. Our results show that three-quarters of the first polar bodies were lost even at the zygotic stage; the 4-cell stage embryos contained only one (second) polar body, and the elimination of second polar bodies proceeded continuously during later development. Both first and second polar bodies showed several typical features of apoptosis: phosphatidylserine redistribution (observed for the first time in the first polar body), specific DNA degradation, condensed nuclear morphology, and inability to exclude cationic dye from the nucleus during the terminal stage of the apoptotic process. Caspase-3 activity was recorded only in the second polar body. From the morphological point of view, mouse polar bodies acted very similarly to damaged embryonic cells which have lost contact with their neighboring blastomeres. In conclusion, polar bodies possess all the molecular equipment necessary for triggering and executing an active suicide process. Furthermore, similarly as in dying embryonic cells, stressing external conditions (culture in vitro) might accelerate and increase the incidence of apoptotic elimination of the polar bodies in embryos.

  20. Solvent/Non-Solvent Sintering To Make Microsphere Scaffolds

    Science.gov (United States)

    Laurencin, Cato T.; Brown, Justin L.; Nair, Lakshmi

    2011-01-01

    A solvent/non-solvent sintering technique has been devised for joining polymeric microspheres to make porous matrices for use as drug-delivery devices or scaffolds that could be seeded with cells for growing tissues. Unlike traditional sintering at elevated temperature and pressure, this technique is practiced at room temperature and pressure and, therefore, does not cause thermal degradation of any drug, protein, or other biochemical with which the microspheres might be loaded to impart properties desired in a specific application. Also, properties of scaffolds made by this technique are more reproducible than are properties of comparable scaffolds made by traditional sintering. The technique involves the use of two miscible organic liquids: one that is and one that is not a solvent for the affected polymer. The polymeric microspheres are placed in a mold having the size and shape of the desired scaffold, then the solvent/non-solvent mixture is poured into the mold to fill the void volume between the microspheres, then the liquid mixture is allowed to evaporate. Some of the properties of the resulting scaffold can be tailored through choice of the proportions of the liquids and the diameter of the microspheres.

  1. Solvent substitution

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    The DOE Environmental Restoration and Waste Management Office of Technology Development and the Air Force Engineering and Services Center convened the First Annual International Workshop on Solvent Substitution on December 4--7, 1990. The primary objectives of this joint effort were to share information and ideas among attendees in order to enhance the development and implementation of required new technologies for the elimination of pollutants associated with industrial use of hazardous and toxic solvents; and to aid in accelerating collaborative efforts and technology transfer between government and industry for solvent substitution. There were workshop sessions focusing on Alternative Technologies, Alternative Solvents, Recovery/Recycling, Low VOC Materials and Treatment for Environmentally Safe Disposal. The 35 invited papers presented covered a wide range of solvent substitution activities including: hardware and weapons production and maintenance, paint stripping, coating applications, printed circuit boards, metal cleaning, metal finishing, manufacturing, compliance monitoring and process control monitoring. This publication includes the majority of these presentations. In addition, in order to further facilitate information exchange and technology transfer, the US Air Force and DOE solicited additional papers under a general Call for Papers.'' These papers, which underwent review and final selection by a peer review committee, are also included in this combined Proceedings/Compendium. For those involved in handling, using or managing hazardous and toxic solvents, this document should prove to be a valuable resource, providing the most up-to-date information on current technologies and practices in solvent substitution. Individual papers are abstracted separated.

  2. Activity and conformation of lysozyme in molecular solvents, protic ionic liquids (PILs) and salt-water systems.

    Science.gov (United States)

    Wijaya, Emmy C; Separovic, Frances; Drummond, Calum J; Greaves, Tamar L

    2016-09-21

    Improving protein stabilisation is important for the further development of many applications in the pharmaceutical, specialty chemical, consumer product and agricultural sectors. However, protein stabilization is highly dependent on the solvent environment and, hence, it is very complex to tailor protein-solvent combinations for stable protein maintenance. Understanding solvent features that govern protein stabilization will enable selection or design of suitable media with favourable solution environments to retain protein native conformation. In this work the structural conformation and activity of lysozyme in 29 solvent systems were investigated to determine the role of various solvent features on the stability of the enzyme. The solvent systems consisted of 19 low molecular weight polar solvents and 4 protic ionic liquids (PILs), both at different water content levels, and 6 aqueous salt solutions. Small angle X-ray scattering, Fourier transform infrared spectroscopy and UV-vis spectroscopy were used to investigate the tertiary and secondary structure of lysozyme along with the corresponding activity in various solvation systems. At low non-aqueous solvent concentrations (high water content), the presence of solvents and salts generally maintained lysozyme in its native structure and enhanced its activity. Due to the presence of a net surface charge on lysozyme, electrostatic interactions in PIL-water systems and salt solutions enhanced lysozyme activity more than the specific hydrogen-bond interactions present in non-ionic molecular solvents. At higher solvent concentrations (lower water content), solvents with a propensity to exhibit the solvophobic effect, analogous to the hydrophobic effect in water, retained lysozyme native conformation and activity. This solvophobic effect was observed particularly for solvents which contained hydroxyl moieties. Preferential solvophobic effects along with bulky chemical structures were postulated to result in less

  3. Driving Forces Controlling Host-Guest Recognition in Supercritical Carbon Dioxide Solvent.

    Science.gov (United States)

    Ingrosso, Francesca; Altarsha, Muhannad; Dumarçay, Florence; Kevern, Gwendal; Barth, Danielle; Marsura, Alain; Ruiz-López, Manuel F

    2016-02-24

    The formation of supramolecular host-guest complexes is a very useful and widely employed tool in chemistry. However, supramolecular chemistry in non-conventional solvents such as supercritical carbon dioxide (scCO2 ), one of the most promising sustainable solvents, is still in its infancy. In this work, we explored a successful route to the development of green processes in supercritical CO2 by combining a theoretical approach with experiments. We were able to synthesize and characterize an inclusion complex between a polar aromatic molecule (benzoic acid) and peracetylated-β-cyclodextrin, which is soluble in the supercritical medium. This finding opens the way to wide, environmental friendly, applications of scCO2 in many areas of chemistry, including supramolecular synthesis, reactivity and catalysis, micro and nano-particle formation, molecular recognition, as well as enhanced extraction processes with increased selectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Solvents and solvent effects in organic chemistry

    National Research Council Canada - National Science Library

    Reichardt, C; Welton, T

    2011-01-01

    .../guest complexation equilibria and reactions in biphasic solvent systems and neoteric solvents, respectively. More than 900 new references have been added, giving preference to review articles, and many older ones have been deleted. New references either replace older ones or are added to the end of the respective reference list of each chapter. Th...

  5. Caustic-Side Solvent Extraction: Chemical and Physical Properties of the Optimized Solvent

    Energy Technology Data Exchange (ETDEWEB)

    Delmau, L.H.

    2002-10-08

    This work was undertaken to optimize the solvent used in the Caustic Side Solvent Extraction (CSSX) process and to measure key chemical and physical properties related to its performance in the removal of cesium from the alkaline high-level salt waste stored in tanks at the Savannah River Site. The need to adjust the solvent composition arose from the prior discovery that the previous baseline solvent was supersaturated with respect to the calixarene extractant. The following solvent-component concentrations in Isopar{reg_sign} L diluent are recommended: 0.007 M calix[4]arene-bis(tert-octylbenzo-crown-6) (BOBCalixC6) extractant, 0.75 M 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol (Cs-7SB) phase modifier, and 0.003 M tri-n-octylamine (TOA) stripping aid. Criteria for this selection included BOBCalixC6 solubility, batch cesium distribution ratios (D{sub Cs}), calculated flowsheet robustness, third-phase formation, coalescence rate (dispersion numbers), and solvent density. Although minor compromises within acceptable limits were made in flowsheet robustness and solvent density, significant benefits were gained in lower risk of third-phase formation and lower solvent cost. Data are also reported for the optimized solvent regarding the temperature dependence of D{sub Cs} in extraction, scrubbing, and stripping (ESS); ESS performance on recycle; partitioning of BOBCalixC6, Cs-7SB, and TOA to aqueous process solutions; partitioning of organic anions; distribution of metals; solvent phase separation at low temperatures; solvent stability to elevated temperatures; and solvent density and viscosity. Overall, the technical risk of the CSSX process has been reduced by resolving previously identified issues and raising no new issues.

  6. Chemical approach to solvent removal during nanoencapsulation: its application to preparation of PLGA nanoparticles with non-halogenated solvent

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngme [Ewha Womans University, College of Pharmacy (Korea, Republic of); Sah, Eric [University of Notre Dame, College of Science (United States); Sah, Hongkee, E-mail: hsah@ewha.ac.kr [Ewha Womans University, College of Pharmacy (Korea, Republic of)

    2015-11-15

    droplets, eventually solidifying them into nanoparticles. It is a simple but effective nanoencapsulation technique that has advantages over typical solvent evaporation and/or extraction methods.

  7. Chemical approach to solvent removal during nanoencapsulation: its application to preparation of PLGA nanoparticles with non-halogenated solvent

    International Nuclear Information System (INIS)

    Lee, Youngme; Sah, Eric; Sah, Hongkee

    2015-01-01

    droplets, eventually solidifying them into nanoparticles. It is a simple but effective nanoencapsulation technique that has advantages over typical solvent evaporation and/or extraction methods

  8. Physics with polarized electrons and targets

    International Nuclear Information System (INIS)

    Donnelly, T.W.

    1984-01-01

    With the advent of electron stretcher or storage rings electron scattering from polarized targets becomes a general new tool for nuclear structure studies. Without such facilities it is necessary to have very dense polarized targets for use with the typical (less or approximately equal 50 μA) electron beams available and very few measurements of this type have been attempted. On the other hand, with electron rings the effective circulating current can be greatly increased. In this case much thinner internal targets may be used while still maintaining the same luminosity as in external beam experiments. In ancticipation of such new experimental capabilities we have re-developed the theoretical basis for discussions of electron scattering from polarized targets using either unpolarized or polarized electron beams. This work takes the formalism of unpolarized (e,e') and extends it in a straightforward way to include general polarizations of electrons, target nuclei, recoil nuclei or any combinations of these polarizations. In the present context it is only possible to provide a brief summary of the general form of the cross section and to present a few illustrative examples of the nuclear structure information that may be extracted from such polarization measurements

  9. The influence of solvent stress on MMS-induced genetic change in Saccharomyces cerevisiae.

    Science.gov (United States)

    Zimmermann, F K; Rohlfs, A

    1991-01-01

    MMS induced mitotic recombination but not mitotic chromosome loss when tested in pure form in strain D61.M of Saccharomyces cerevisiae, confirming previous results of Albertini (1991), whereas in Aspergillus nidulans it also induced chromosomal malsegregation in addition to mitotic recombination (Käfer, 1988). However, induction of mitotic chromosome loss was observed in combination with strong inducers of chromosome loss such as the aprotic polar solvents ethyl acetate and to a lesser extent methyl ethyl ketone but not with gamma-valerolactone and propionitrile. In addition to this, 4 solvents, dimethyl formamide, dimethyl sulfoxide, dioxane and pyridine, enhanced the MMS-induced mitotic recombination in strain D61.M. An enhancement of MMS-induced mitotic recombination and reverse mutation could be demonstrated for ethyl acetate and gamma-valerolactone in yeast strain D7.

  10. Solvent Clathrate Driven Dynamic Stereomutation of a Supramolecular Polymer with Molecular Pockets.

    Science.gov (United States)

    Kulkarni, Chidambar; Korevaar, Peter A; Bejagam, Karteek K; Palmans, Anja R A; Meijer, E W; George, Subi J

    2017-10-04

    Control over the helical organization of synthetic supramolecular systems is intensively pursued to manifest chirality in a wide range of applications ranging from electron spin filters to artificial enzymes. Typically, switching the helicity of supramolecular assemblies involves external stimuli or kinetic traps. However, efforts to achieve helix reversal under thermodynamic control and to understand the phenomena at a molecular level are scarce. Here we present a unique example of helix reversal (stereomutation) under thermodynamic control in the self-assembly of a coronene bisimide that has a 3,5-dialkoxy substitution on the imide phenyl groups (CBI-35CH), leading to "molecular pockets" in the assembly. The stereomutation was observed only if the CBI monomer possesses molecular pockets. Detailed chiroptical studies performed in alkane solvents with different molecular structures reveal that solvent molecules intercalate or form clathrates within the molecular pockets of CBI-35CH at low temperature (263 K), thereby triggering the stereomutation. The interplay among the helical assembly, molecular pockets, and solvent molecules is further unraveled by explicit solvent molecular dynamics simulations. Our results demonstrate how the molecular design of self-assembling building blocks can orchestrate the organization of surrounding solvent molecules, which in turn dictates the helical organization of the resulting supramolecular assembly.

  11. In vitro biocompatibility and proliferative effects of polar and non-polar extracts of cucurbita ficifolia on human mesenchymal stem cells.

    Science.gov (United States)

    Aristatile, Balakrishnan; Alshammari, Ghedeir M

    2017-05-01

    Cucurbita ficifolia (C. ficifolia) has been traditionally known for its medicinal properties as an antioxidant, anti-diabetic and anti-inflammatory agent. However, there has been an enduring attention towards the identification of unique method, to isolate the natural components for therapeutic applications. Our study focuses on different polar and non-polar solvents (methanol, hexane and chloroform) to extract the bioactive components from C. ficifolia (pumpkin) and to study the biocompatibility and cytotoxicity effects on human bone marrow-mesenchymal stem cells (hBM-MSCs). The extracts were screened for their effects on cytotoxicity, cell proliferation and cell cycle on the hBM-MSCs cell line. The assays demonstrated that the chloroform extract was highly biocompatible, with less cytotoxic effect, and enhanced the cell proliferation. The methanol extract did not exhibit significant cytotoxicity when compare to the control. Concordantly, the cell cycle analysis confirmed that chloroform extract enhances the proliferation at lower concentrations. On the other hand, hexane extract showed high level of cytotoxicity with apoptotic and necrotic changes in hBM-MSCs. Collectively, our data revealed that chloroform is a good candidate to extract the bioactive components from C. ficifolia. Furthermore, our results suggest that specific gravity and density of the solvent might play a crucial role in the extraction process, which warrants further investigations. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  12. Results Of The Extraction-Scrub-Strip Testing Using An Improved Solvent Formulation And Salt Waste Processing Facility Simulated Waste

    International Nuclear Information System (INIS)

    Peters, T.; Washington, A.; Fink, S.

    2012-01-01

    The Office of Waste Processing, within the Office of Technology Innovation and Development, is funding the development of an enhanced solvent - also known as the next generation solvent (NGS) - for deployment at the Savannah River Site to remove cesium from High Level Waste. The technical effort is a collaborative effort between Oak Ridge National Laboratory (ORNL) and Savannah River National Laboratory (SRNL). As part of the program, the Savannah River National Laboratory (SRNL) has performed a number of Extraction-Scrub-Strip (ESS) tests. These batch contact tests serve as first indicators of the cesium mass transfer solvent performance with actual or simulated waste. The test detailed in this report used simulated Tank 49H material, with the addition of extra potassium. The potassium was added at 1677 mg/L, the maximum projected (i.e., a worst case feed scenario) value for the Salt Waste Processing Facility (SWPF). The results of the test gave favorable results given that the potassium concentration was elevated (1677 mg/L compared to the current 513 mg/L). The cesium distribution value, DCs, for extraction was 57.1. As a comparison, a typical D Cs in an ESS test, using the baseline solvent formulation and the typical waste feed, is ∼15. The Modular Caustic Side Solvent Extraction Unit (MCU) uses the Caustic-Side Solvent Extraction (CSSX) process to remove cesium (Cs) from alkaline waste. This process involves the use of an organic extractant, BoBCalixC6, in an organic matrix to selectively remove cesium from the caustic waste. The organic solvent mixture flows counter-current to the caustic aqueous waste stream within centrifugal contactors. After extracting the cesium, the loaded solvent is stripped of cesium by contact with dilute nitric acid and the cesium concentrate is transferred to the Defense Waste Processing Facility (DWPF), while the organic solvent is cleaned and recycled for further use. The Salt Waste Processing Facility (SWPF), under

  13. Precise determination of the degree of polarization of a cold neutron beam

    International Nuclear Information System (INIS)

    Nastoll, H.; Schreckenbach, K.; Baglin, C.; Bussiere, A.; Guillaud, J.P.; Kossakowski, R.; Liaud, P.

    1991-01-01

    A cold neutron beam at the ILL High Flux Reactor was used to produce highly polarized neutrons by means of a bent supermirror polarizer. A following current sheet spin flipper allowed the change of the neutron spin direction relative to the guiding magnetic fields. The degree of polarization of the beam was measured as a function of the neutron velocity in the range 300-1500 m/s achieving an accuracy of 0.2% at typically 98% polarization. Two spin flippers and the permutation of three supermirror polarizers as polarizer/analyzer were employed. (orig.)

  14. Solvent extraction of indium and gallium complexes with bromopyrogallol red by mixed extractants containing chloroform, a polar organic solvent and monocarboxylic acids

    International Nuclear Information System (INIS)

    Pyatnitskij, I.V.; Lysenko, O.V.; Kolomiets, L.L.

    1987-01-01

    Solvent extraction of indium and gallium complexes with bromopyragallol red (BPR) has been studied using mixed extractants containing chloroform, capronic acid (HL) and 1-pentanol (S) (extractant 1), and chloroform, HL, S and propionic acid (extractant 2). The latter is more selectie and extracts only the indium complex. Optimal conditions have been found for the extraction of In-BRP complex (pH 6.3-6.5; C BPR 1.5x10 -4 M) its composition has been estimated and discussed

  15. Description of the equilibrium conditions of chemical reactions in various solvents

    International Nuclear Information System (INIS)

    Roehl, H.

    1983-01-01

    Empirical knowledge is taken as the basis for establishing a method to predict the equilibrium conditions of reactions of macrocyclic polyethers and monovalent metal cations in various solvents. The reactions in the solvents under review can be well described by the donor number DN according to Gutmann, and by the parameters alpha and pi-asterisk for the H bonding donor and polarity/polarisability, respectively, using a three-parameter equation according to Kamlet/Taft. This applies to both protic and aprotic solvents. The calculations rely on data found in the literature and on own experimental results obtained by microcalorimetric examinations. The evaluation methods evolved for this purpose also allow, by means of additional dilution experiments, to convert the ''integral'', microcalorimetrically obtained complex stability constants, (i.e. those non-discriminating between different types of state such as ions or ion pairs) to the corresponding ''differentiating'' constants (referring to purely ionic quantities), and this applied to the various solvents used. The method does not use foreign ions and can thus also be applied to those cases for which the normal standardisation of reaction conditions published in the literature cannot be maintained (e.g. for reasons of solubility). In some cases it was possible to obtain additional information on the dissociation behaviour of the salts used, which revealed differently strong inclination to form higher aggregations in solution, as shown e.g. by the strong concentration dependence of the salt ion pair dissociation constants obtained. (orig./EF) [de

  16. Glymes as benign co-solvents for CaO-catalyzed transesterification of soybean oil to biodiesel.

    Science.gov (United States)

    Tang, Shaokun; Zhao, Hua; Song, Zhiyan; Olubajo, Olarongbe

    2013-07-01

    The base (such as CaO)-catalyzed heterogeneous preparation of biodiesel encounters a number of obstacles including the need for CaO pretreatment and the reactions being incomplete (typically 90-95% yields). In this study, a number of glymes were investigated as benign solvents for the CaO-catalyzed transesterification of soybean oil into biodiesel with a high substrate loading (typically soybean oil >50% v/v). The triglyceride-dissolving capability of glymes led to a much faster reaction rate (>98% conversions in 4h) than in methanol alone (typically 24h) and minimized the saponification reaction when catalyzed by anhydrous CaO or commercial lime without pre-activation. The use of glyme (e.g. P2) as co-solvent also activates commercial lime to become an effective catalyst without calcination pretreatment. The SEM images suggest a dissolution-agglomeration process of CaO surface in the presence of P2, which could remove the CaCO3 and Ca(OH)2 layer coated on the surface of lime. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. The chemistry of nonaqueous solvents v.4 solution phenomena and aprotic solvents

    CERN Document Server

    Lagowski, J J

    1976-01-01

    The Chemistry of Nonaqueous Solvents, Volume IV: Solution Phenomena and Aprotic Solvents focuses on the chemistry of nonaqueous solvents, with emphasis on solution phenomena and aprotic solvents such as tetramethylurea, inorganic acid chlorides, cyclic carbonates, and sulfolane. This book is organized into seven chapters and begins with an overview of the theory of electrical conductivity and elementary experimental considerations, along with some of the interesting research on nonaqueous solvents. It then turns to a discussion on hydrogen bonding phenomena in nonaqueous systems as probed

  18. Amphiphilic invertible polymers: Self-assembly into functional materials driven by environment polarity

    Science.gov (United States)

    Hevus, Ivan

    Stimuli-responsive polymers adapt to environmental changes by adjusting their chain conformation in a fast and reversible way. Responsive polymeric materials have already found use in electronics, coatings industry, personal care, and bio-related areas. The current work aims at the development of novel responsive functional polymeric materials by manipulating environment-dependent self-assembly of a new class of responsive macromolecules strategically designed in this study,—amphiphilic invertible polymers (AIPs). Environment-dependent micellization and self-assembly of three different synthesized AIP types based on poly(ethylene glycol) as a hydrophilic fragment and varying hydrophobic constituents was demonstrated in polar and nonpolar solvents, as well as on the surfaces and interfaces. With increasing concentration, AIP micelles self-assemble into invertible micellar assemblies composed of hydrophilic and hydrophobic domains. Polarity-responsive properties of AIPs make invertible micellar assemblies functional in polar and nonpolar media including at interfaces. Thus, invertible micellar assemblies solubilize poorly soluble substances in their interior in polar and nonpolar solvents. In a polar aqueous medium, a novel stimuli-responsive mechanism of drug release based on response of AIP-based drug delivery system to polarity change upon contact with the target cell has been established using invertible micellar assemblies loaded with curcumin, a phytochemical drug. In a nonpolar medium, invertible micellar assemblies were applied simultaneously as nanoreactors and stabilizers for size-controlled synthesis of silver nanoparticles stable in both polar and nonpolar media. The developed amphiphilic nanosilver was subsequently used as seeds to promote anisotropic growth of CdSe semiconductor nanoparticles that have potential in different applications ranging from physics to medicine. Amphiphilic invertible polymers were shown to adsorb on the surface of silica

  19. A solvent/non-solvent system for achieving solution-processed multilayer organic light-emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yue; Wu, Zhaoxin, E-mail: zhaoxinwu@mail.xjtu.edu.cn; He, Lin; Jiao, Bo; Hou, Xun

    2015-08-31

    We developed a solvent/non-solvent system to fabricate the multilayer organic light-emitting devices (OLEDs) based on poly(N-vinylcarbazole) (PVK) by solution-process. This solvent system consists of both the solvent and non-solvent of PVK, in which fluorescent small molecules could be fully dissolved and directly spin-coated on top of the PVK layer; it could effectively avoid the redissolution of PVK during the spin-coating process of small molecules emitting layer. In the further investigation of this system, we also demonstrated the three-component solvent system, and found out that the third component, a less volatile solvent of PVK, was crucial for preparing a smoother interface between PVK and emitting layer. Compared with OLEDs through the vacuum deposition, the devices fabricated by solution-process from the solvent/non-solvent system showed comparable efficiency, which indicate that the solvent/non-solvent system can be used as an alternative process to prepare the polymer and small molecule multilayer devices through all-solution-process. - Highlights: • We fabricate the multilayer OLEDs by solution-process using a novel system. • We develop a solvent/non-solvent system of polymer (PVK) to avoid redissolution. • Small molecules could be fully dissolved and directly spin-coated on PVK layer. • The devices fabricated by the system and vacuum deposition show comparable efficiency.

  20. Anhydrous formic acid and acetic anhydride as solvent or additive in nonaqueous titrations.

    Science.gov (United States)

    Buvári-Barcza, A; Tóth, I; Barcza, L

    2005-09-01

    The use and importance of formic acid and acetic anhydride (Ac2O) is increasing in nonaqueous acid-base titrations, but their interaction with the solutes is poorly understood. This paper attempts to clarify the effect of the solvents; NMR and spectrophotometric investigations were done to reveal the interactions between some bases and the mentioned solvents. Anhydrous formic acid is a typical protogenic solvent but both the relative permittivity and acidity are higher than those of acetic acid (mostly used in assays of bases). These differences originate from the different chemical structures: liquid acetic acid contains basically cyclic dimers while formic acid forms linear associates. Ac2O is obviously not an acidic but an aprotic (very slightly protophilic) solvent, which supposedly dissociates slightly into acetyl (CH3CO+) and acetate (AcO-) ions. In fact, some bases react with Ac2O forming an associate: the Ac+ group is bound to the delta- charged atom of the reactant while AcO- is associated with the delta+ group at appropriate distance.

  1. Aqueous solutions that model the cytosol : studies on polarity, chemical reactivity and enzyme kinetics

    NARCIS (Netherlands)

    Asaad, N.; den Otter, M.J.; Engberts, J.B.F.N.

    2004-01-01

    Concentrated solutions of a series of organic compounds have been prepared and the effects of these solutes on the properties of the solvent system assessed as a function of their concentration and nature. Polarity, as measured by Reichardt's E-T(30) probe, exhibits a linear variation with both

  2. RETRIEVAL OF AEROSOL PHASE FUNCTION AND POLARIZED PHASE FUNCTION FROM POLARIZATION OF SKYLIGHT FOR DIFFERENT OBSERVATION GEOMETRIES

    Directory of Open Access Journals (Sweden)

    L. Li

    2018-04-01

    Full Text Available The phase function and polarized phase function are important optical parameters, which describe scattering properties of atmospheric aerosol particles. Polarization of skylight induced by the scattering processes is sensitive to the scattering properties of aerosols. The Stokes parameters I, Q, U and the polarized radiance Lp of skylight measured by the CIMEL dual-polar sun-sky radiometer CE318- DP can be use to retrieve the phase function and polarized phase function, respectively. Two different observation geometries (i.e., the principal plane and almucantar are preformed by the CE318-DP to detect skylight polarization. Polarization of skylight depends on the illumination and observation geometries. For the same solar zenith angle, retrievals of the phase function and the polarized phase function are still affected by the observation geometry. The performance of the retrieval algorithm for the principal plane and almucantar observation geometries was assessed by the numerical experiments at two typical high and low sun’s positions (i.e. solar zenith angles are equal to 45° and 65°. Comparing the results for the principal plane and almucantar geometries, it is recommended to utilize the principal plane observations to retrieve the phase function when the solar zenith angle is small. The Stokes parameter U and the polarized radiance Lp from the almucantar observations are suggested to retrieve the polarized phase function, especially for short wavelength channels (e.g., 440 and 500 nm.

  3. Retrieval of Aerosol Phase Function and Polarized Phase Function from Polarization of Skylight for Different Observation Geometries

    Science.gov (United States)

    Li, L.; Qie, L. L.; Xu, H.; Li, Z. Q.

    2018-04-01

    The phase function and polarized phase function are important optical parameters, which describe scattering properties of atmospheric aerosol particles. Polarization of skylight induced by the scattering processes is sensitive to the scattering properties of aerosols. The Stokes parameters I, Q, U and the polarized radiance Lp of skylight measured by the CIMEL dual-polar sun-sky radiometer CE318- DP can be use to retrieve the phase function and polarized phase function, respectively. Two different observation geometries (i.e., the principal plane and almucantar) are preformed by the CE318-DP to detect skylight polarization. Polarization of skylight depends on the illumination and observation geometries. For the same solar zenith angle, retrievals of the phase function and the polarized phase function are still affected by the observation geometry. The performance of the retrieval algorithm for the principal plane and almucantar observation geometries was assessed by the numerical experiments at two typical high and low sun's positions (i.e. solar zenith angles are equal to 45° and 65°). Comparing the results for the principal plane and almucantar geometries, it is recommended to utilize the principal plane observations to retrieve the phase function when the solar zenith angle is small. The Stokes parameter U and the polarized radiance Lp from the almucantar observations are suggested to retrieve the polarized phase function, especially for short wavelength channels (e.g., 440 and 500 nm).

  4. The Geissen polarization facility. I

    International Nuclear Information System (INIS)

    Arnold, W.; Berg, H.; Krause, H.H.; Ulbricht, J.; Clausnitzer, G.

    1977-01-01

    A source for the production of polarized negative hydrogen or deuterium ions following the Lambshift method is described. A duoplasmatron with expansion cup and extended ion optics is used. The polarization is generated by a diabetic zero field passage of the metastable atoms. For precision experiments the polarization can be switched 'on' and 'off' with a frequency of 1 kHz by a disturbance with a transverse magnetic field. The quantization axis can be rotated with a Wien filter. All source components are installed in a compact vacuum chamber, which allows high effective pumping speeds. The overal length of the source including the Wien filter is 1.7m. With a 10mm diameter cesium canal typical H - currents of 0.6-0.75 μA (P=0.7-0.75) and maximum currents of 0.9μA are obtained. (Auth.)

  5. Effect of temperature on the transport of solvents through PTMSP under ultra-high pressures

    International Nuclear Information System (INIS)

    Grekhov, A M; Belogorlov, A A; Eremin, Yu S; Pastukhova, E V; Yushkin, A A; Volkov, A V

    2016-01-01

    Despite a large number of studies, by now there is no any definitive explanation of the solvent transport mechanism in nanostructured polymer materials. Both convective and diffusive transport of solvents can be observed in these materials. The study of the solvents permeability at different temperatures and pressures allow the variation of the physical parameters and structure of the solvent-membrane interaction thus becoming the key factor in the understanding of the fundamental aspects of the selective transport process in nanostructured polymer membranes. The paper presents the study of ethanol, propanol and water transport through poly [1- (trimethylsilyl)-l-propine] (PTMSP) at pressures 50-150 atm and temperature up to 90°C. The study was done by the method of pressure dynamic decay. As the temperature rises, the permeability of ethanol and propanol through PTMSP is shown to increase in proportion to decreasing viscosity that denotes a convective type of transport. As for water, the permeability change is thermo-activated that is typical for a diffusive type of transport. This difference in the transport characteristics can be related to a change in the membrane structure and energetic characteristics of the solvent-polymer interaction. (paper)

  6. Analysis of solvent extracts from coal liquefaction in a flowing solvent reactor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wen-Ying; Feng, Jie; Xie, Ke-Chang [Key Laboratory of Coal Science and Technology, Taiyuan University of Technology, Ministry of Education and Shanxi Province, No. 79 Yingze West Street, Taiyuan 030024 (China); Kandiyoti, R. [Department of Chemical Engineering and Chemical Technology, Imperial College, University of London, London SW7 2BY (United Kingdom)

    2004-10-15

    Point of Ayr coal has been extracted using three solvents, tetralin, quinoline and 1-methyl-2-pyrrolidinone (NMP) at two temperatures 350 and 450 C, corresponding approximately to before and after the onset of massive covalent bond scission by pyrolysis. The three solvents differ in solvent power and the ability to donate hydrogen atoms to stabilise free radicals produced by pyrolysis of the coal. The extracts were prepared in a flowing solvent reactor to minimise secondary thermal degradation of the primary extracts. Analysis of the pentane-insoluble fractions of the extracts was achieved by size exclusion chromatography, UV-fluorescence spectroscopy in NMP solvent and probe mass. With increasing extraction temperature, the ratio of the amount having big molecular weight to that having small molecular weight in tetralin extracts was increased; the tetralin extract yield increased from 12.8% to 75.9%; in quinoline, increasing extraction temperature did not have an effect on the molecular weight of products but there was a big increase in extract yield. The extracts in NMP showed the enhanced solvent extraction power at both temperatures, with a shift in the ratio of larger molecules to smaller molecules with increasing extraction temperature and with the highest conversion of Point of Ayr coal among these three solvents at both temperatures. Solvent adducts were detected in the tetralin and quinoline extracts by probe mass spectrometry; solvent products were formed from NMP at both temperatures.

  7. Potentiometric investigations of (acid+base) equilibria in (n-butylamine+acetic acid) systems in binary (acetone+cyclohexane) solvent mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Czaja, MaIgorzata [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Kozak, Anna [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Makowski, Mariusz [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Chmurzynski, Lech [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)]. E-mail: lech@chem.univ.gda.pl

    2005-08-15

    By using the potentiometric titration method, standard equilibrium constants have been determined of acid dissociation of molecular acid, K{sub a}(HA), cationic acid, K{sub a}(BH{sup +}), of anionic and cationic homoconjugation, K{sub AHA{sup -}}andK{sub BHB{sup +}}, respectively, and of molecular heteroconjugation, K{sub AHB} (K{sub BHA}), in (acid+base) systems without proton transfer consisting of n-butylamine and acetic acid in binary (acetone+cyclohexane) solvent mixtures. The results have shown that both the pK{sub a}(HA) and pK{sub a}(BH{sup +}), as well as lgK{sub AHA{sup -}} values change non-linearly as a function of composition of the solvent mixture. On the other hand, standard molecular heteroconjugation constants without proton transfer do not depend on the cyclohexane content in the mixture, i.e. on solvent polarity.

  8. The Solvent Selection framework: solvents for organic synthesis, separation processes and ionic-organic synthesis

    DEFF Research Database (Denmark)

    Mitrofanov, Igor; Sansonetti, Sascha; Abildskov, Jens

    2012-01-01

    This paper presents a systematic integrated framework for solvent selection and solvent design. The framework is divided into several modules, which can tackle specific problems in various solvent-based applications. In particular, three modules corresponding to the following solvent selection pr...

  9. Solvent effects in the synergistic solvent extraction of Co2+

    International Nuclear Information System (INIS)

    Kandil, A.T.; Ramadan, A.

    1979-01-01

    The extraction of Co 2+ from a 0.1M ionic strength aqueous phase (Na + , CH 3 COOH) of pH = 5.1 was studied using thenoyltrifluoroacetone, HTTA, in eight different solvents and HTTA + trioctylphosphine oxide, TOPO, in the same solvents. A comparison of the effect of solvent dielectric constant on the equilibrium constant shows a synergism as a result of the increased hydrophobic character imparted to the metal complex due to the formation of the TOPO adduct. (author)

  10. SOLVENT FIRE BY-PRODUCTS

    Energy Technology Data Exchange (ETDEWEB)

    Walker, D; Samuel Fink, S

    2006-05-22

    Southwest Research Institute (SwRI) conducted a burn test of the Caustic-Side Solvent Extraction (CSSX) solvent to determine the combustion products. The testing showed hydrogen fluoride gas is not a combustion product from a solvent fire when up to 70% of the solvent is consumed. The absence of HF in the combustion gases may reflect concentration of the modifier containing the fluoride groups in the unburned portion. SwRI reported results for other gases (CO, HCN, NOx, formaldehyde, and hydrocarbons). The results, with other supporting information, can be used for evaluating the consequences of a facility fire involving the CSSX solvent inventory.

  11. An overview of industrial solvent use or is there life after chlorinated solvents?

    International Nuclear Information System (INIS)

    Green, B.

    1991-01-01

    Everyone using industrial chemicals has been affected by the fire- storm of new regulations governing solvent use. How will companies currently using hazardous solvents prepare for the changes ahead? What will the impact be on commonly used industrial solvents? What effect are environmental pressures having on solvent use and disposal? Are the responsible individuals in your company up-to-date on phase-out schedules? This paper is written for an audience of compliance coordinators, consultants, production engineers and corporate management. In it, the either addresses the above questions and discusses the specific products affected. The author reviews currently available alternatives to chlorinated and hazardous solvents and introduces a simple system for rating alternatives. The program also includes a discussion of solvent minimization programs and worker reeducation

  12. The effects of solvents and structure on the electronic absorption spectra of the isomeric pyridine carboxylic acid N-oxides

    Directory of Open Access Journals (Sweden)

    Drmanić Saša Ž.

    2013-01-01

    Full Text Available The ultraviolet absorption spectra of the carboxyl group of three isomeric pyridine carboxylic acids N-oxides (picolinic acid N-oxide, nicotinic acid N-oxide and isonicotinic acid N-oxide were determined in fourteen solvents in the wavelength range from 200 to 400 nm. The position of the absorption maxima (λmax of the examined acids showed that the ultraviolet absorption maximum wavelengths of picolinic acid N-oxide are the shortest, and those of isonicotinic acid N-oxide acid are the longest. In order to analyze the solvent effect on the obtained absorption spectra, the ultraviolet absorption frequencies of the electronic transitions in the carboxylic group of the examined acids were correlated using a total solvatochromic equation of the form max = v0 + sπ + aα+ bβ, where υmax is the absorption frequency (1/λmax, p is a measure of the solvent polarity, β represents the scale of solvent hydrogen bond acceptor basicities and α represent the scale of solvent hydrogen bond donor acidities. The correlation of the spectroscopic data was carried out by means of multiple linear regression analysis. The solvent effects on the ultraviolet absorption maximums of the examined acids were discussed.

  13. High-power laser diodes with high polarization purity

    Science.gov (United States)

    Rosenkrantz, Etai; Yanson, Dan; Peleg, Ophir; Blonder, Moshe; Rappaport, Noam; Klumel, Genady

    2017-02-01

    Fiber-coupled laser diode modules employ power scaling of single emitters for fiber laser pumping. To this end, techniques such as geometrical, spectral and polarization beam combining (PBC) are used. For PBC, linear polarization with high degree of purity is important, as any non-perfectly polarized light leads to losses and heating. Furthermore, PBC is typically performed in a collimated portion of the beams, which also cancels the angular dependence of the PBC element, e.g., beam-splitter. However, we discovered that single emitters have variable degrees of polarization, which depends both on the operating current and far-field divergence. We present data to show angle-resolved polarization measurements that correlate with the ignition of high-order modes in the slow-axis emission of the emitter. We demonstrate that the ultimate laser brightness includes not only the standard parameters such as power, emitting area and beam divergence, but also the degree of polarization (DoP), which is a strong function of the latter. Improved slow-axis divergence, therefore, contributes not only to high brightness but also high beam combining efficiency through polarization.

  14. Polarization-sensitive electro-optic detection of terahertz wave using three different types of crystal symmetry: Toward broadband polarization spectroscopy

    International Nuclear Information System (INIS)

    Oguchi, Kenichi; Iwasaki, Hotsumi; Okano, Makoto; Watanabe, Shinichi

    2016-01-01

    We investigated polarization-sensitive electro-optic (EO) detection of terahertz (THz) waves by using two uniaxial crystals: a c-cut gallium selenide and a c-cut lithium niobate crystals. We formulated a general frequency-domain description of EO detection by in-plane isotropic EO crystals, which holds regardless of the frequency. Based on this description, the polarization of THz waves can be derived by analyzing EO sampling signals measured with two orthogonal configurations of the in-plane isotropic EO crystals as well as typical (111) zinc-blende EO crystals. In addition, we experimentally demonstrated that the frequency-dependent polarization of THz waves can be reproducibly retrieved using three EO crystals with different crystal symmetries and with different phase matching conditions. Our description provides essential information for practical polarization sensing in the THz frequency range as well as in the mid-infrared range

  15. Rapid, facile synthesis of conjugated polymer zwitterions in ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Page, Zachariah A. [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA; Liu, Feng [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA; Russell, Thomas P. [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA; Emrick, Todd [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA

    2014-01-01

    Ionic liquids (ILs) were utilized for the rapid air-stable Suzuki polymerization of polar zwitterionic thiophene monomers, precluding the need for volatile organic solvents, phosphine ligands and phase transfer catalysts typically used in conjugated polymer synthesis.

  16. Extraction of microalgal lipids and the influence of polar lipids on biodiesel production by lipase-catalyzed transesterification.

    Science.gov (United States)

    Navarro López, Elvira; Robles Medina, Alfonso; González Moreno, Pedro Antonio; Esteban Cerdán, Luis; Molina Grima, Emilio

    2016-09-01

    In order to obtain microalgal saponifiable lipids (SLs) fractions containing different polar lipid (glycolipids and phospholipids) contents, SLs were extracted from wet Nannochloropsis gaditana microalgal biomass using seven extraction systems, and the polar lipid contents of some fractions were reduced by low temperature acetone crystallization. We observed that the polar lipid content in the extracted lipids depended on the polarity of the first solvent used in the extraction system. Lipid fractions with polar lipid contents between 75.1% and 15.3% were obtained. Some of these fractions were transformed into fatty acid methyl esters (FAMEs, biodiesel) by methanolysis, catalyzed by the lipases Novozym 435 and Rhizopus oryzae in tert-butanol medium. We observed that the reaction velocity was higher the lower the polar lipid content, and that the final FAME conversions achieved after using the same lipase batch to catalyze consecutive reactions decreased in relation to an increase in the polar lipid content. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Solvent - solute interaction

    International Nuclear Information System (INIS)

    Urbanczyk, A.; Kalinowski, M.K.

    1983-01-01

    The electronic absorption spectrum of vanadyl acetylacetonate has been studied in 15 organic solvents. It has been found that wavenumbers and molar absorptivities of the long-wavelength bands (d-d transitions) can be well described by a complementary Lewis acid-base model including Gutmann's donor number [Gutmann V., Wychera E., Inorg. Nucl. Chem. Letters 2, 257 (1966)] and acceptor number [Mayer U., Gutmann V., Gerger W., Monatsh. Chem. 106, 1235 (1975)] of a solvent. This model describes also the solvent effect of the hyperfine splitting constant, Asub(iso)( 51 V), from e.s.r. spectra of VOacac 2 . These observations are discussed in terms of the donor-acceptor concept for solvent-solute interactions. (Author)

  18. Deasphalting solvents

    International Nuclear Information System (INIS)

    Carrillo, J. A; Caceres, J; Vela, G; Bueno, H

    1996-01-01

    This paper describes how the deasphalted oil (DMO) or demetalized oil (DMO) quality (CCR, Ni, V end asphaltenes contents) changes with: DAO or DMO yield, solvent/feed ratio, type of vacuum reside (from paraffinic to blends with vis breaking bottoms), extraction temperature and extraction solvent (propane, propylene, n-butane and I butane)

  19. Theoretical study of chain transfer to solvent reactions of alkyl acrylates.

    Science.gov (United States)

    Moghadam, Nazanin; Srinivasan, Sriraj; Grady, Michael C; Rappe, Andrew M; Soroush, Masoud

    2014-07-24

    This computational and theoretical study deals with chain transfer to solvent (CTS) reactions of methyl acrylate (MA), ethyl acrylate (EA), and n-butyl acrylate (n-BA) self-initiated homopolymerization in solvents such as butanol (polar, protic), methyl ethyl ketone (MEK) (polar, aprotic), and p-xylene (nonpolar). The results indicate that abstraction of a hydrogen atom from the methylene group next to the oxygen atom in n-butanol, from the methylene group in MEK, and from a methyl group in p-xylene by a live polymer chain are the most likely mechanisms of CTS reactions in MA, EA, and n-BA. Energy barriers and molecular geometries of reactants, products, and transition states are predicted. The sensitivity of the predictions to three hybrid functionals (B3LYP, X3LYP, and M06-2X) and three different basis sets (6-31G(d,p), 6-311G(d), and 6-311G(d,p)) is investigated. Among n-butanol, sec-butanol, and tert-butanol, tert-butanol has the highest CTS energy barrier and the lowest rate constant. Although the application of the conductor-like screening model (COSMO) does not affect the predicted CTS kinetic parameter values, the application of the polarizable continuum model (PCM) results in higher CTS energy barriers. This increase in the predicted CTS energy barriers is larger for butanol and MEK than for p-xylene. The higher rate constants of chain transfer to n-butanol reactions compared to those of chain transfer to MEK and p-xylene reactions suggest the higher CTS reactivity of n-butanol.

  20. Membrane curvature, lipid segregation, and structural transitions for phospholipids under dual-solvent stress

    International Nuclear Information System (INIS)

    Rand, R.P.; Fuller, N.L.; Gruner, S.M.; Parsegian, V.A.

    1990-01-01

    Amphiphiles respond both to polar and to nonpolar solvents. In this paper X-ray diffraction and osmotic stress have been used to examine the phase behavior, the structural dimensions, and the work of deforming the monolayer-lined aqueous cavities formed by mixtures of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC) as a function of the concentration of two solvents, water and tetradecane (td). In the absence of td, most PE/PC mixtures show only lamellar phases in excess water; all of these become single reverse hexagonal (H II ) phases with addition of excess td. The spontaneous radius of curvature R 0 of lipid monolayers, as expressed in these H II phases, is allowed by the relief of hydrocarbon chain stress by td; R 0 increases with the ratio DOPC/DOPE. Single H II phases stressed by limited water or td show several responses. (a) the molecular area is compressed at the polar end of the molecule and expanded at the hydrocarbon ends. (b) For circularly symmetrical water cylinders, the degrees of hydrocarbon chain splaying and polar group compression are different for molecules aligned in different directions around the water cylinder. (c) A pivotal position exists along the length of the phospholipid molecule where little area change occurs as the monolayer is bent to increasing curvatures. (d) By defining R 0 at the pivotal position, the authors find that measured energies are well fit by a quadratic bending energy. (e) For lipid mixtures, enforced deviation of the H II monolayer from R 0 is sufficiently powerful to cause demixing of the phospholipids in a way suggesting that the DOPE/DOPC ratio self-adjusts so that its R 0 matches the amount of td or water available, i.e., that curvature energy is minimized

  1. Role of solvent environments in single molecule conductance used insulator-modified mechanically controlled break junctions

    Science.gov (United States)

    Muthusubramanian, Nandini; Maity, Chandan; Galan Garcia, Elena; Eelkema, Rienk; Grozema, Ferdinand; van der Zant, Herre; Kavli Institute of Nanoscience Collaboration; Department of Chemical Engineering Collaboration

    We present a method for studying the effects of polar solvents on charge transport through organic/biological single molecules by developing solvent-compatible mechanically controlled break junctions of gold coated with a thin layer of aluminium oxide using plasma enhanced atomic layer deposition (ALD). The optimal oxide thickness was experimentally determined to be 15 nm deposited at ALD operating temperature of 300°C which yielded atomically sharp electrodes and reproducible single-barrier tunnelling behaviour across a wide conductance range between 1 G0 and 10-7 G0. The insulator protected MCBJ devices were found to be effective in various solvents such as deionized water, phosphate buffered saline, methanol, acetonitrile and dichlorobenzene. The yield of molecular junctions using such insulated electrodes was tested by developing a chemical protocol for synthesizing an amphipathic form of oligo-phenylene ethynylene (OPE3-PEO) with thioacetate anchoring groups. This work has further applications in studying effects of solvation, dipole orientation and other thermodynamic interactions on charge transport. Eu Marie Curie Initial Training Network (ITN). MOLECULAR-SCALE ELECTRONICS: ``MOLESCO'' Project Number 606728.

  2. Solvent exposure and related work practices amongst apprentice spray painters in automotive body repair workshops.

    Science.gov (United States)

    Winder, C; Turner, P J

    1992-08-01

    As part of a multidisciplinary study into the health effects of solvents, workplace assessments and airborne solvent vapour monitoring was conducted in 46 spray painting workshops in the Sydney metropolitan area. Breathing-zone samples were taken from 50 apprentices and 14 experienced spray painters. An interview schedule was developed to obtain information about the use of acrylic or two-pack paint systems, the use of engineering controls, the use of personal protective equipment and the availability of material safety data sheets. Contaminants typical of the chemical products used in this industry were encountered (aromatic hydrocarbons, C5-C7 aliphatic hydrocarbons, ketones, esters). The results of airborne solvent monitoring indicate a total solvent exposure in the range 1-99% of a combined Worksafe Australia exposure standard, with a mean of 19%. Solvent exposure was highest when spraying acrylic paint in the open workshop and lowest when spraying two pack paint in a spray booth. Much the same personal protective equipment was available in all workshops, but wide variation in its use was observed. Material safety data sheets were not observed in any of the workshops.

  3. Well-constructed cellulose acetate membranes for forward osmosis: Minimized internal concentration polarization with an ultra-thin selective layer

    KAUST Repository

    Zhang, Sui; Wang, Kaiyu; Chung, Tai Shung Neal; Chen, Hongmin; Jean, Yanching; Amy, Gary L.

    2010-01-01

    polarization (ECP) and ICP, and the St value of the double dense-layer membrane is much smaller than those reported in literatures. Furthermore, the effects of an intermediate immersion into a solvent/water mixed bath prior to complete immersion in water

  4. Solvent cleaning system and method for removing contaminants from solvent used in resin recycling

    Science.gov (United States)

    Bohnert, George W [Harrisonville, MO; Hand, Thomas E [Lee's Summit, MO; DeLaurentiis, Gary M [Jamestown, CA

    2009-01-06

    A two step solvent and carbon dioxide based system that produces essentially contaminant-free synthetic resin material and which further includes a solvent cleaning system for periodically removing the contaminants from the solvent so that the solvent can be reused and the contaminants can be collected and safely discarded in an environmentally safe manner.

  5. Studies on the effect of solvents on self-assembly of thioctic acid and Mercaptohexanol on gold

    Energy Technology Data Exchange (ETDEWEB)

    Li Zhiguo; Niu Tianxing [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry of China and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China); Zhang Zhenjiang [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry of China and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China); College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215006 (China); Feng Guiying [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry of China and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China); Bi Shuping, E-mail: bisp@nju.edu.c [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry of China and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China)

    2011-04-29

    In this article we investigated the effect of solvents (CCl{sub 4}, CH{sub 3}CN, DMF, ethanol, ethanol-H{sub 2}O and H{sub 2}O) on self-assembly of Thioctic acid (TA) and Mercaptohexanol (MCH) on gold by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Electrochemical characteristics of TA and MCH self-assembled monolayers (SAMs) formed in different solvents were evaluated by inspecting the ions permeability (interfacial capacitance C and phase angle {phi}{sub 1Hz}) and electron transfer capability (current density difference {Delta}i and charge transfer resistance R{sub ct}). Experimental results indicated that the ability of solvents availing the ordering of SAMs was: for TA, CCl{sub 4} > ethanol > CH{sub 3}CN > ethanol-H{sub 2}O > DMF; for MCH, H{sub 2}O > ethanol-H{sub 2}O {approx} CCl{sub 4} > ethanol {approx} CH{sub 3}CN > DMF. Through relating the C, {phi}{sub 1Hz}, {Delta}i and R{sub ct} of SAMs (TA and MCH) with parameters of solvent (polarity E{sub T}{sup N}, solubility parameter {delta} and octanol/water partition coefficients logP{sub ow}), it was found that solvents with bigger logP{sub ow} (smaller E{sub T}{sup N} and {delta}) availed the ordering of TA-SAMs but the effect of solvents on MCH self-assembly was complex and MCH-SAMs formed in H{sub 2}O (the biggest E{sub T}{sup N}, {delta} and the smallest logP{sub ow}) and CCl{sub 4} (the smallest E{sub T}{sup N}, {delta} and the biggest logP{sub ow}) were more ordered than in other solvents.

  6. Photoreactivity of biologically active compounds. XVII. Influence of solvent interactions on spectroscopic properties and photostability of primaquine.

    Science.gov (United States)

    Kristensen, S

    2005-06-01

    The influence of solvent interactions on absorption properties, fluorescence properties (emission spectra and quantum yields) and relative photochemical degradation rates of primaquine has been investigated, in order to evaluate photochemical reaction mechanisms and chemical properties of the compound. The first absorption band (n - pi*) of primaquine is only slightly dependent on properties of the solvent, which can be ascribed to a strong, intramolecular hydrogen bond between the quinoline N and amine group in the ground state (S0). Amphiprotic solvents with predominant acidic properties (water and methanol) will to some extent stabilize the molecule and initiate hypsochromic shifts of the absorption band by protic interactions, while the other solvents (amphiprotic, basic and neutral) influence the absorption spectrum by general solvent effects only. The excited singlet (S1*) state of primaquine interacts more efficiently with the surrounding solvents than the S0 state, as evaluated by the Stokes shifts. The pKa value of the quinoline N is likely to increase in the S1* state, which is important for the observed protic interactions with amphiprotic solvents of predominant acidity. Specific solvent effects are highly important for the efficiency of the fluorescence (fluorescence quantum yields; phi f). The fluorescence is quenched by amphiprotic solvents, likely due to a rupture of the intramolecular bond and protonation of the quinolone N, and enhanced by polar, non-protic (basic) solvents, probably by stabilization of the delta intramolecular hydrogen bond. The observed photochemical degradation rates of primaquine in amphiprotic media are positively correlated with phi f, indicating that the photochemical degradation of primaquine is dependent on intramolecular hydrogen bonding and non protonated lone-pair electrons at the quinoline N. The intramolecular ring-formation with a subsequent increased lipophilic character and (lack of) interactions with the

  7. Characterization and antioxidant activity of bovine serum albumin and sulforaphane complex in different solvent systems

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Xueyan; Zhou, Rui; Jing, Hao, E-mail: h200521@cau.edu.cn

    2014-02-15

    Modes and influencing factors of bovine serum albumin (BSA) and sulforaphane (SFN) interaction will help us understand the interaction mechanisms and functional changes of bioactive small molecule and biomacromolecule. This study investigated interaction mechanisms of BSA and SFN and associated antioxidant activity in three solvent systems of deionized water (dH{sub 2}O), dimethyl sulfoxide (DMSO) and ethanol (EtOH), using Fourier transform infrared spectroscopy (FT-IR), fluorescence spectroscopy, synchronous fluorescence spectroscopy, DPPH and ABTS radical scavenging assays. The results revealed that SFN had ability to quench BSA's fluorescence in static modes, and to interact with BSA at both tyrosine (Tyr) and tryptophan (Trp) residues, while the Trp residues were highly sensitive, which was demonstrated by fluorescence at 340 nm. Hydrophobic forces, hydrogen bonds and van der Waals interactions were all involved in BSA and SFN interaction, which were not significantly changed by three solvents. The binding constant values and binding site numbers were in a descending order of dH{sub 2}O>DMSO>EtOH. The values of free energy change were in a descending order of dH{sub 2}O>DMSO>EtOH, which indicated that the binding forces were in a descending order of dH{sub 2}O>DMSO>EtOH. There was no significant difference in antioxidant activity between SFN and BSA–SFN. Moreover, three solvents had not significant influence on antioxidant activity of SFN and BSA–SFN. -- Highlights: • We report interaction mechanisms of BSA and sulforaphane in three solvent systems. • We report antioxidant activity of BSA–sulforaphane complex in three solvent systems. • Decreasing the solvent polarity will decrease the binding of BSA and sulforaphane. • Three solvents had not influence on antioxidant activity of BSA–sulforaphane.

  8. Anti-Solvent Crystallization Strategies for Highly Efficient Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Maria Konstantakou

    2017-09-01

    Full Text Available Solution-processed organic-inorganic halide perovskites are currently established as the hottest area of interest in the world of photovoltaics, ensuring low manufacturing cost and high conversion efficiencies. Even though various fabrication/deposition approaches and device architectures have been tested, researchers quickly realized that the key for the excellent solar cell operation was the quality of the crystallization of the perovskite film, employed to assure efficient photogeneration of carriers, charge separation and transport of the separated carriers at the contacts. One of the most typical methods in chemistry to crystallize a material is anti-solvent precipitation. Indeed, this classical precipitation method worked really well for the growth of single crystals of perovskite. Fortunately, the method was also effective for the preparation of perovskite films by adopting an anti-solvent dripping technique during spin-coating the perovskite precursor solution on the substrate. With this, polycrystalline perovskite films with pure and stable crystal phases accompanied with excellent surface coverage were prepared, leading to highly reproducible efficiencies close to 22%. In this review, we discuss recent results on highly efficient solar cells, obtained by the anti-solvent dripping method, always in the presence of Lewis base adducts of lead(II iodide. We present all the anti-solvents that can be used and what is the impact of them on device efficiencies. Finally, we analyze the critical challenges that currently limit the efficacy/reproducibility of this crystallization method and propose prospects for future directions.

  9. Analysis of solvent dyes in refined petroleum products by electrospray ionization mass spectrometry

    Science.gov (United States)

    Rostad, C.E.

    2010-01-01

    Solvent dyes are used to color refined petroleum products to enable differentiation between gasoline, diesel, and jet fuels. Analysis for these dyes in the hydrocarbon product is difficult due to their very low concentrations in such a complex matrix. Flow injection analysis/electrospray ionization/mass spectrometry in both negative and positive mode was used to optimize ionization of ten typical solvent dyes. Samples of hydrocarbon product were analyzed under similar conditions. Positive electrospray ionization produced very complex spectra, which were not suitably specific for targeting only the dyes. Negative electrospray ionization produced simple spectra because aliphatic and aromatic moieties were not ionized. This enabled screening for a target dye in samples of hydrocarbon product from a spill.

  10. [Analysis of organic solvent poisonings occurring in Japan from 1995 to 2006].

    Science.gov (United States)

    Maki, Syou; Nawata, Hideki; Ogawa, Yasutaka

    2011-01-01

    Statistical analyses based on incidence rate were carried out for organic solvent poisonings occurring in Japan. We used the published data of "Typical cases of occupational diseases" and "Current situation of occupational disease occurrence" in the "Industrial Hygiene Guidebook (Roudoueisei no Shiori)". The number of workers as a population of occupational solvent handlers was obtained from the Ministry of Health, Labour and Welfare, Japan. The annual incidences of solvent poisoning from 1995 to 2006, poisoning, death-by-poisoning, and secondary poisoning were 3.3-5.4, 0.0-0.83, and 0.0-0.34 cases/(100,000 solvent handlers × yr), respectively. Annual incidence classified by manufacturing, construction, and other services were 2.5, 52.0, and 6.1, respectively. Manufacturing showed a small increase from 1999 to 2003, and stopped increasing after 2004. Construction had a peak in 2000. Other services notably decreased from 14.4 in 1999 to 2.5 in 2006. The monthly distribution of the number of poisoning cases was prominent in January. Annual incidences of poisoning, death-by-poisoning, and secondary poisoning were 3.9, 0.5, 0.2 for toluene, 3.5, 0.5, 0.3 for xylene, and 16.4, 4.7, 2.3 for trichloroethylene, respectively. The annual incidences classified by industry and solvents showed no change for manufacturing, whereas that for construction notably decreased from 88.6 in 2000 to 12.0 in 2006.

  11. Solvent dielectric effect and side chain mutation on the structural stability of Burkholderia cepacia lipase active site: a quantum mechanical/molecular mechanics study.

    Science.gov (United States)

    Tahan, A; Monajjemi, M

    2011-12-01

    Quantum mechanical and molecular dynamics methods were used to analyze the structure and stability of neutral and zwitterionic configurations of the extracted active site sequence from a Burkholderia cepacia lipase, histidyl-seryl-glutamin (His86-Ser87-Gln88) and its mutated form, histidyl-cysteyl-glutamin (His86-Cys87-Gln88) in vacuum and different solvents. The effects of solvent dielectric constant, explicit and implicit water molecules and side chain mutation on the structure and stability of this sequence in both neutral and zwitterionic forms are represented. The quantum mechanics computations represent that the relative stability of zwitterionic and neutral configurations depends on the solvent structure and its dielectric constant. Therefore, in vacuum and the considered non-polar solvents, the neutral form of the interested sequences is more stable than the zwitterionic form, while their zwitterionic form is more stable than the neutral form in the aqueous solution and the investigated polar solvents in most cases. However, on the potential energy surfaces calculated, there is a barrier to proton transfer from the positively charged ammonium group to the negatively charged carboxylat group or from the ammonium group to the adjacent carbonyl oxygen and or from side chain oxygen and sulfur to negatively charged carboxylat group. Molecular dynamics simulations (MD) were also performed by using periodic boundary conditions for the zwitterionic configuration of the hydrated molecules in a box of water molecules. The obtained results demonstrated that the presence of explicit water molecules provides the more compact structures of the studied molecules. These simulations also indicated that side chain mutation and replacement of sulfur with oxygen leads to reduction of molecular flexibility and packing.

  12. Bio-Inspired Sensing and Imaging of Polarization Information in Nature

    Science.gov (United States)

    2008-05-04

    Neurobiology of polarization vision,” Trends Neu- rosci. 12, 353–359 (1989). 32. R. Wehner, “‘Matched filters’: neural models of the external world,” J...degrees of polarization,” J. Exp. Biol. 199, 1467–1475 (1996). 47. T. Labhart and E. P. Meyer, Neural mechanisms in insect navigation: polarization...mm by 0.3–0.5 in. 7.6–12.7 mm while a typical ight bulb is 3 in. 76 mm in diameter and needs to be laced at least 7 in. 177.8 mm from the

  13. Zeno inhibition of polarization rotation in an optically active medium

    International Nuclear Information System (INIS)

    Gonzalo, Isabel; Luis, Alfredo; Porras, Miguel A

    2015-01-01

    We describe an experiment in which the rotation of the polarization of light propagating in an optically active water solution of D-fructose tends to be inhibited by frequent monitoring whether the polarization remains unchanged. This is an example of the Zeno effect that has remarkable pedagogical interest because of its conceptual simplicity, easy implementation, low cost, and because the same the Zeno effect holds at classical and quantum levels. An added value is the demonstration of the Zeno effect beyond typical idealized assumptions in a practical setting with real polarizers. (paper)

  14. The Indigo Molecule Revisited Again: Assessment of the Minnesota Family of Density Functionals for the Prediction of Its Maximum Absorption Wavelengths in Various Solvents

    Directory of Open Access Journals (Sweden)

    Francisco Cervantes-Navarro

    2013-01-01

    Full Text Available The Minnesota family of density functionals (M05, M05-2X, M06, M06L, M06-2X, and M06-HF were evaluated for the calculation of the UV-Vis spectra of the indigo molecule in solvents of different polarities using time-dependent density functional theory (TD-DFT and the polarized continuum model (PCM. The maximum absorption wavelengths predicted for each functional were compared with the known experimental results.

  15. Geissen polarization facility. I. Lambshift source

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, W; Berg, H; Krause, H H; Ulbricht, J; Clausnitzer, G [Giessen Univ. (Germany, F.R.). Strahlenzentrum

    1977-06-15

    A source for the production of polarized negative hydrogen or deuterium ions following the Lambshift method is described. A duoplasmatron with expansion cup and extended ion optics is used. The polarization is generated by a diabetic zero field passage of the metastable atoms. For precision experiments the polarization can be switched 'on' and 'off' with a frequency of 1 kHz by a disturbance with a transverse magnetic field. The quantization axis can be rotated with a Wien filter. All source components are installed in a compact vacuum chamber, which allows high effective pumping speeds. The overal length of the source including the Wien filter is 1.7m. With a 10mm diameter cesium canal typical H/sup -/ currents of 0.6-0.75 ..mu..A (P=0.7 to 0.75) and maximum currents of 0.9..mu..A are obtained.

  16. The Polarized Electron Source at ELSA

    International Nuclear Information System (INIS)

    Drachenfels, Wolther von; Frommberger, Frank; Gowin, Michael; Hillert, Wolfgang; Hoffmann, Markus; Neff, Bernhold

    2003-01-01

    At the electron stretcher accelerator ELSA in Bonn a pulsed 50 kV inverted gun of polarized electrons has been in operation since February 2000. A strained-layer superlattice crystal is used to deliver a beam with a polarization of about 80 %. A flashlamp-pumped Ti-Sapphire laser with a pulse repetition rate of 50 Hz serves as source of light. The gun is operated in space charge limitation. The current can be chosen by varying the distance between cathode and anode. With 1 μs pulses of 100 mA the source was particularly used together with a polarized target for a GDH sum rule experiment. The high photocathode lifetime allows continuous operation at 100 mA typically for periods of about two weeks without maintenance. So far no change of the crystal was necessary

  17. A potentiometric study of molecular heteroconjugation equilibria in (n-butylamine+acetic acid) systems in binary (acetonitrile +1,4-dioxane) solvent mixtures

    International Nuclear Information System (INIS)

    Czaja, Malgorzata; Makowski, Mariusz; Chmurzynski, Lech

    2006-01-01

    By using the potentiometric method the following quantities have been determined: acidity constants of molecular acid, K a (HA), of cationic acid, K a (BH + ), anionic and cationic homoconjugation constants, K AHA - and K BHB + , respectively, as well as molecular heteroconjugation constants, K AHB , in (n-butylamine+acetic acid) systems without proton transfer in binary (acetonitrile+1,4-dioxane), AN+D, solvent mixtures. The results of these measurements have shown that the magnitudes of the molecular heteroconjugation constants do not depend on the 1,4-dioxane content in the mixed solvent, i.e., on solvent polarity. It has also been found that in the (acid+base) systems without proton transfer, the manner of carrying out the titration (direct B+HA vs. reverse HA+B) does not affect the magnitudes of the molecular heteroconjugation constants

  18. Induced Polarization Influences the Fundamental Forces in DNA Base Flipping

    OpenAIRE

    Lemkul, Justin A.; Savelyev, Alexey; MacKerell, Alexander D.

    2014-01-01

    Base flipping in DNA is an important process involved in genomic repair and epigenetic control of gene expression. The driving forces for these processes are not fully understood, especially in the context of the underlying dynamics of the DNA and solvent effects. We studied double-stranded DNA oligomers that have been previously characterized by imino proton exchange NMR using both additive and polarizable force fields. Our results highlight the importance of induced polarization on the base...

  19. Solvent effect on polystyrene surface roughness on top of QCM sensor

    Energy Technology Data Exchange (ETDEWEB)

    Sakti, Setyawan P., E-mail: sakti@ub.ac.id; Rahmawati, Eka; Robiandi, Fadli [Advanced System and Material Technology, Laboratory of Instrumentation and Measurement Department of Physics, Brawijaya University (Indonesia)

    2016-03-11

    Quartz Crystal Microbalance (QCM) has been used as a basis for many chemical sensors and biosensor. Its sensitivity to mass change which can detect a mass change on its surface down to sub ng/cm2 is one of its interesting aspects. Another interesting feature is its ability to work in liquid environment. However, there are many aspects which influence QCM sensor properties in contact with liquid. One of the aspects is surface roughness of the matrix layer where on top of it a biological sensitive layer will be immobilized. One of matrix layers in the immobilizing biological sensitive layer was polystyrene. Polystyrene was coated on the QCM sensor by using the spin coating method. During the coating process, polystyrene was solved using non-polar solvent. It is known that the physical and chemical properties of the solvent affect a transition process from soluble polymer becoming rigid polymer layer. In this work, we show that polystyrene solved in chloroform has a higher surface roughness compare to one solved in toluene, xylene, or tetrahydrofuran. Surface roughness of the polystyrene coating were measured using a non-contact profilometer. However, we also found that there is no difference on the electrical impedance of the QCM sensor coated with polystyrene resulted from differing solvent when the sensor was in contact with air and water. Thus, all of the mentioned solvent can be used to solve the polystyrene as a coating material for QCM sensor without affecting the electrical performance of the sensor, but the choice of the solution can be used as a simple method to control the difference roughness of the polystyrene coating.

  20. Two novel solvent system compositions for protected synthetic peptide purification by centrifugal partition chromatography.

    Science.gov (United States)

    Amarouche, Nassima; Giraud, Matthieu; Forni, Luciano; Butte, Alessandro; Edwards, F; Borie, Nicolas; Renault, Jean-Hugues

    2014-04-11

    Protected synthetic peptide intermediates are often hydrophobic and not soluble in most common solvents. They are thus difficult to purify by preparative reversed-phase high-performance liquid chromatography (RP-HPLC), usually used for industrial production. It is then challenging to develop alternative chromatographic purification processes. Support-free liquid-liquid chromatographic techniques, including both hydrostatic (centrifugal partition chromatography or CPC) and hydrodynamic (counter-current chromatography or CCC) devices, are mainly involved in phytochemical studies but have also been applied to synthetic peptide purification. In this framework, two new biphasic solvent system compositions covering a wide range of polarity were developed to overcome solubility problems mentioned above. The new systems composed of heptane/tetrahydrofuran/acetonitrile/dimethylsulfoxide/water and heptane/methyl-tetrahydrofuran/N-methylpyrrolidone/water were efficiently used for the CPC purification of a 39-mer protected exenatide (Byetta®) and a 8-mer protected peptide intermediate of bivalirudin (Angiox®) synthesis. Phase compositions of the different biphasic solvent systems were determined by (1)H nuclear magnetic resonance. Physico-chemical properties including viscosity, density and interfacial tension of these biphasic systems are also described. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Study of the efectiveness of the mixed solvents for radically removing thiophenes from benzene and toluene by extractive rectification

    Energy Technology Data Exchange (ETDEWEB)

    Miroshnicenko, A.A.; Fedosyuk, A.A.

    1981-01-01

    A study has been made of the selectivity of solvents under the conditions of liquid-liquid equilibrium in the systems which include thiophene, benzene, toluene, the polar solvent and n-decane. The presence of the latter has maintained the heterogeneity of the mixtures being studied. The systems under consideration were drawn up in volumetric ratios. Equilibrium was studied in thermostat units. The equilibrium phases were analyzed by a special method, while the coefficient of the relative distribution of the components with respect to selectivity was calculated by the known relations. The investigations of the systems with different solvents have shown that there are functionally selective classes of extractants in which selectivity is determined by free unsubstituted functional groups of a solvent. The growth of the selectivity of solvents according to the following classes has been observed: aprotic ones with a keto group < protic ones with a hydroxyl < < unsubstituted amides of acids < sulphones < sulphoxides. To study the liquid-vapor equilibrium, use was made of the most selective extractants (including DMSO, Pyrrolidone-2, carbamide, ethylene carbamide, and NMP) which were revealed earlier in extraction investigations. Since the most selective representative of acid amides, namely, ethylene carbamide and carbamide, are solids, they were studied in mixtures with the less selective liquid solvents of NMP and pyrrolidone-2. NMP-ethylene-carbamide-water and pyrrolidone-2-ethylene carbamida-water are the most selective mixed solvents, and preference is given to the latter one.

  2. Electrically polarized PLLA nanofibers as neural tissue engineering scaffolds with improved neuritogenesis.

    Science.gov (United States)

    Barroca, Nathalie; Marote, Ana; Vieira, Sandra I; Almeida, Abílio; Fernandes, Maria H V; Vilarinho, Paula M; da Cruz E Silva, Odete A B

    2018-07-01

    Tissue engineering is evolving towards the production of smart platforms exhibiting stimulatory cues to guide tissue regeneration. This work explores the benefits of electrical polarization to produce more efficient neural tissue engineering platforms. Poly (l-lactic) acid (PLLA)-based scaffolds were prepared as solvent cast films and electrospun aligned nanofibers, and electrically polarized by an in-lab built corona poling device. The characterization of the platforms by thermally stimulated depolarization currents reveals a polarization of 60 × 10 -10 C cm -2 that is stable on poled electrospun nanofibers for up to 6 months. Further in vitro studies using neuroblastoma cells reveals that platforms' polarization potentiates Retinoic Acid-induced neuronal differentiation. Additionally, in differentiating embryonic cortical neurons, poled aligned nanofibers further increased neurite outgrowth by 30% (+70 μm) over non-poled aligned nanofibers, and by 50% (+100 μm) over control conditions. Therefore, the synergy of topographical cues and electrical polarization of poled aligned nanofibers places them as promising biocompatible and bioactive platforms for neural tissue regeneration. Given their long lasting induced polarization, these PLLA poled nanofibrous scaffolds can be envisaged as therapeutic devices of long shelf life for neural repair applications. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Porous fiber formation in polymer-solvent system undergoing solvent evaporation

    Science.gov (United States)

    Dayal, Pratyush; Kyu, Thein

    2006-08-01

    Temporal evolution of the fiber morphology during dry spinning has been investigated in the framework of Cahn-Hilliard equation [J. Chem. Phys. 28, 258 (1958)] pertaining to the concentration order parameter or volume fraction given by the Flory-Huggins free energy of mixing [P. J. Flory, Principles of Polymer Chemistry (Cornell University Press, Ithaca, NY, 1953), p. 672] in conjunction with the solvent evaporation rate. To guide the solvent evaporation induced phase separation, equilibrium phase diagram of the starting polymer solution was established on the basis of the Flory-Huggins free energy of mixing. The quasi-steady-state approximation has been adopted to account for the nonconserved nature of the concentration field caused by the solvent loss. The process of solvent evaporation across the fiber skin-air interface was treated in accordance with the classical Fick's law [R. B. Bird et al., Transport Phenomena (J. Wiley, New York, 1960), p. 780]. The simulated morphologies include gradient type, hollow fiber type, bicontinuous type, and host-guest type. The development of these diverse fiber morphologies is explicable in terms of the phase diagram of the polymer solution in a manner dependent on the competition between the phase separation dynamics and rate of solvent evaporation.

  4. Essential roles of protein-solvent many-body correlation in solvent-entropy effect on protein folding and denaturation: Comparison between hard-sphere solvent and water

    International Nuclear Information System (INIS)

    Oshima, Hiraku; Kinoshita, Masahiro

    2015-01-01

    In earlier works, we showed that the entropic effect originating from the translational displacement of water molecules plays the pivotal role in protein folding and denaturation. The two different solvent models, hard-sphere solvent and model water, were employed in theoretical methods wherein the entropic effect was treated as an essential factor. However, there were similarities and differences in the results obtained from the two solvent models. In the present work, to unveil the physical origins of the similarities and differences, we simultaneously consider structural transition, cold denaturation, and pressure denaturation for the same protein by employing the two solvent models and considering three different thermodynamic states for each solvent model. The solvent-entropy change upon protein folding/unfolding is decomposed into the protein-solvent pair (PA) and many-body (MB) correlation components using the integral equation theories. Each component is further decomposed into the excluded-volume (EV) and solvent-accessible surface (SAS) terms by applying the morphometric approach. The four physically insightful constituents, (PA, EV), (PA, SAS), (MB, EV), and (MB, SAS), are thus obtained. Moreover, (MB, SAS) is discussed by dividing it into two factors. This all-inclusive investigation leads to the following results: (1) the protein-water many-body correlation always plays critical roles in a variety of folding/unfolding processes; (2) the hard-sphere solvent model fails when it does not correctly reproduce the protein-water many-body correlation; (3) the hard-sphere solvent model becomes problematic when the dependence of the many-body correlation on the solvent number density and temperature is essential: it is not quite suited to studies on cold and pressure denaturating of a protein; (4) when the temperature and solvent number density are limited to the ambient values, the hard-sphere solvent model is usually successful; and (5) even at the ambient

  5. Restoring solvent for nuclear separation processes

    International Nuclear Information System (INIS)

    Reif, D.J.

    1987-01-01

    Solvent extraction separation processes are used to recover usable nuclear materials from spent fuels. These processes involve the use of an extractant/diluent (solvent) for separation of the reusable actinides from unwanted fission products. The most widely used processes employ tributyl phosphate as an extractant diluted with a normal-paraffin hydrocarbon. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials that influence product losses, product decontamination, and separation efficiencies. In most processes, the solvent is recycled after cleaning. Solvent cleaning generally involves scrubbing with a sodium carbonate solution. Studies at the Savannah River Laboratory have shown that carbonate washing, although removing residual solvent activity, does not remove more solvent-soluble binding ligands (formed by solvent degradation), which hold fission products in the solvent. Treatment of the solvent with a solid adsorbent after carbonate washing removes binding ligands and significantly improves recycled solvent performance. Laboratory work to establish the advantage of adsorbent cleaning and the development of a full-scale adsorption process is described. The application of this process for cleaning the first cycle solvent of a Savannah River Plant production process is discussed

  6. Selective solvent extraction of oils

    Energy Technology Data Exchange (ETDEWEB)

    1938-04-09

    In the selective solvent extraction of naphthenic base oils, the solvent used consists of the extract obtained by treating a paraffinic base oil with a selective solvent. The extract, or partially spent solvent is less selective than the solvent itself. Selective solvents specified for the extraction of the paraffinic base oil are phenol, sulphur dioxide, cresylic acid, nitrobenzene, B:B/sup 1/-dichlorethyl ether, furfural, nitroaniline and benzaldehyde. Oils treated are Coastal lubricating oils, or naphthenic oils from the cracking, or destructive hydrogenation of coal, tar, lignite, peat, shale, bitumen, or petroleum. The extraction may be effected by a batch or counter-current method, and in the presence of (1) liquefied propane, or butane, or naphtha, or (2) agents which modify the solvent power such as, water, ammonia, acetonitrile, glycerine, glycol, caustic soda or potash. Treatment (2) may form a post-treatment effected on the extract phase. In counter-current treatment in a tower some pure selective solvent may be introduced near the raffinate outlet to wash out any extract therefrom.

  7. Effect of Viscosity and Polar Properties of Solvent on Dynamics of Photoinduced Charge Transfer in BTA-1 Cation — Derivative of Thioflavin T

    Science.gov (United States)

    Gogoleva, S. D.; Stsiapura, V. I.

    2018-05-01

    It was found that the spectral and fluorescent properties of BTA-1C cation in protic and aprotic solvents differ. It was shown that for solutions in long-chain alcohols viscosity is the main factor that determines the dynamics of intramolecular charge transfer in the excited state of the BTA-1C molecule. In the case of aprotic solvents a correlation was found between the rate constant of twisted intramolecular charge transfer (TICT) during rotation of fragments of the molecule in relation to each other in the excited state and the solvent relaxation rate: k TICT 1/τ S .

  8. An analog VLSI chip emulating polarization vision of Octopus retina.

    Science.gov (United States)

    Momeni, Massoud; Titus, Albert H

    2006-01-01

    Biological systems provide a wealth of information which form the basis for human-made artificial systems. In this work, the visual system of Octopus is investigated and its polarization sensitivity mimicked. While in actual Octopus retina, polarization vision is mainly based on the orthogonal arrangement of its photoreceptors, our implementation uses a birefringent micropolarizer made of YVO4 and mounted on a CMOS chip with neuromorphic circuitry to process linearly polarized light. Arranged in an 8 x 5 array with two photodiodes per pixel, each consuming typically 10 microW, this circuitry mimics both the functionality of individual Octopus retina cells by computing the state of polarization and the interconnection of these cells through a bias-controllable resistive network.

  9. Operation of the optically pumped polarized H- source at LAMPF

    International Nuclear Information System (INIS)

    York, R.L.; Tupa, D.; Swenson, D.R.; van Dyck, O.B.

    1991-01-01

    We report on the first five months of operation of the Optically Pumped Polarized Ion Source (OPPIS) for the nuclear physics research program at LAMPF. The LAMPF OPPIS is unique in using Ti: Sapphire lasers to polarize the potassium charge-exchange medium, and until recently was unique in using a superconducting magnet in the ECR source and polarizer regions. The ECR extraction electrode biasing arrangement is also unique. Typical performance was 25 microamps of peak current (measured at 750 keV) with 55% beam polarization or 15 microamps at 62%. Ion source availability was greater than 90%. We also report our planned improvements in preparation for research operation in May of 1991. 3 refs., 4 figs

  10. Surface tension of a coal extract in an organic solvent; Sekitan chushutsu seibun no kaigo to hyomen choryoku

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, T.; Hayasaka, K.; Takanohashi, T.; Iino, M. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science

    1996-10-28

    The behavior and properties of associated bodies were studied through measurement of surface tension considering acetone-soluble fraction relatively light among various solvent extracts of coal. In experiment, the acetone-soluble fraction was extracted from the substances extracted from Upper Freeport coal as standard specimen using the mixed solvent of carbon disulfide (CS2) and N-methyl-2-pyrrolidinone (NMP), and it was dissolved into NMP after drying. Surface tension was measured by Wilhelmy method. The experimental results are as follows. Equilibrium surface tension is equal to the surface tension of pure solvent in a low concentration range of solution, and decreases with an increase in concentration approaching a fixed value at 0 in log concentration, nearly showing an S curve. Adsorption of species with non-polar aromatic ring of the acetone-soluble fraction on a solution surface probably decreases surface tension. Change with time in surface tension is observed which suggests fast initial reaction and slow subsequent reaction. 4 figs.

  11. Process for removing halogenated aliphatic and aromatic compounds from petroleum products. [Polychlorinated biphenyls; methylene chloride; perchloroethylene; trichlorofluoroethane; trichloroethylene; chlorobenzene

    Science.gov (United States)

    Googin, J.M.; Napier, J.M.; Travaglini, M.A.

    1982-03-31

    A process for removing halogenated aliphatic and aromatic compounds, e.g., polychlorinated biphenyls, from petroleum products by solvent extraction. The halogenated aliphatic and aromatic compounds are extracted from a petroleum product into a polar solvent by contracting the petroleum product with the polar solvent. The polar solvent is characterized by a high solubility for the extracted halogenated aliphatic and aromatic compounds, a low solubility for the petroleum product and considerable solvent power for polyhydroxy compound. The preferred polar solvent is dimethylformamide. A miscible polyhydroxy compound, such as, water, is added to the polar extraction solvent to increase the polarity of the polar extraction solvent. The halogenated aliphatic and aromatic compounds are extracted from the highly-polarized mixture of polyhydroxy compound and polar extraction solvent into a low polar or nonpolar solvent by contacting the polyhydroxy compound-polar solvent mixture with the low polar or nonpolar solvent. The halogenated aliphatic and aromatic compounds in the low polar or nonpolar solvent by physical means, e.g., vacuum evaporation. The polar and nonpolar solvents are recovered for recycling. The process can easily be designed for continuous operation. Advantages of the process include that the polar solvent and a major portion of the nonpolar solvent can be recycled, the petroleum products are reclaimable and the cost for disposing of waste containing polychlorinated biphenyls is significantly reduced. 2 tables.

  12. Experimental study and thermodynamic modeling for determining the effect of non-polar solvent (hexane)/polar solvent (methanol) ratio and moisture content on the lipid extraction efficiency from Chlorella vulgaris.

    Science.gov (United States)

    Malekzadeh, Mohammad; Abedini Najafabadi, Hamed; Hakim, Maziar; Feilizadeh, Mehrzad; Vossoughi, Manouchehr; Rashtchian, Davood

    2016-02-01

    In this research, organic solvent composed of hexane and methanol was used for lipid extraction from dry and wet biomass of Chlorella vulgaris. The results indicated that lipid and fatty acid extraction yield was decreased by increasing the moisture content of biomass. However, the maximum extraction efficiency was attained by applying equivolume mixture of hexane and methanol for both dry and wet biomass. Thermodynamic modeling was employed to estimate the effect of hexane/methanol ratio and moisture content on fatty acid extraction yield. Hansen solubility parameter was used in adjusting the interaction parameters of the model, which led to decrease the number of tuning parameters from 6 to 2. The results indicated that the model can accurately estimate the fatty acid recovery with average absolute deviation percentage (AAD%) of 13.90% and 15.00% for the two cases of using 6 and 2 adjustable parameters, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. The second-order polarization propagator approximation (SOPPA) method coupled to the polarizable continuum model

    DEFF Research Database (Denmark)

    Eriksen, Janus Juul; Solanko, Lukasz Michal; Nåbo, Lina J.

    2014-01-01

    2) wave function coupled to PCM, we introduce dynamical PCM solvent effects only in the Random Phase Approximation (RPA) part of the SOPPA response equations while the static solvent contribution is kept in both the RPA terms as well as in the higher order correlation matrix components of the SOPPA...... response equations. By dynamic terms, we refer to contributions that describe a change in environmental polarization which, in turn, reflects a change in the core molecular charge distribution upon an electronic excitation. This new combination of methods is termed PCM-SOPPA/RPA. We apply this newly...... defined method to the challenging cases of solvent effects on the lowest and intense electronic transitions in o-, m- and p-nitroaniline and o-, m- and p-nitrophenol and compare the performance of PCM-SOPPA/RPA with more conventional approaches. Compared to calculations based on time-dependent density...

  14. Solvent substitutes

    International Nuclear Information System (INIS)

    Evanoff, S.P.

    1995-01-01

    The environmental and industrial hygiene regulations promulgated since 1980, most notably the Superfund Amendments and Reauthorization Act (SARA), the Hazardous and Solid Waste Amendments to the Resources Conservation and Recovery Act (RCRA), and the Clean Air Act Amendments of 1990, have brought about an increased emphasis on user exposure, hazardous waste generation, and air emissions. As a result, industry is performing a fundamental reassessment of cleaning solvents, processes, and procedures. The more progressive organizations have made their goal the elimination of solvents that may pose significant potential human health and environmental hazards. This chapter discusses solvent cleaning in metal-finishing, metal-manufacturing, and industrial maintenance applications; precision cleaning; and electronics manufacturing. Nonmetallic cleaning, adhesives, coatings, inks, and aerosols also will be addressed, but in a more cursory manner

  15. The structure of the interface in the solvent mediated interaction of dipolar surfaces

    International Nuclear Information System (INIS)

    Dzhavakhidze, P.G.; Levadny, V.G.

    1987-08-01

    Interaction of two dipolar surfaces separated by a polar medium is considered within the framework of nonlocal electrostatics. The dipolar surface layers are modelled as regular lattices with fixed orientation of dipoles which are immersed into the solvent; solvent response is characterized by nonlocal dielectric function. The model is elaborated in order to reveal the role of the dipolar layer discreteness in the electric field produced by one surface and the interaction between two surfaces (which gives rise to the so called ''hydration'' or ''structural'' force acting between mineral surfaces and phospholipid bilayers). The discreteness effects are present only for commensurate lattices. Their special mutual arrangement then may lead to considerable reduction of structural forces, viz. the usual repulsion regime may change at short distances to attraction. Conditions are considered when repulsion is entirely replaced by attraction, i.e. the ''hydration barrier'' disappears. In appended note we discuss the role of solvation of surface dipolar groups. We propose an explanation of why two modes of decay (one with oscillative fine structure) may be present in the dependence of the force upon distance if the surface dipolar groups are immersed deep enough in the solvent and how the long-range oscillative mode disappears when the surface is but weakly solvated. (author). 35 refs, 5 figs

  16. The structure of the interface in the solvent-mediated interaction of dipolar surfaces

    International Nuclear Information System (INIS)

    Dzhavakhidze, P.G.; Kornyshev, A.A.; Levadny, V.G.

    1988-01-01

    Interaction of two dipolar surfaces separated by a polar medium is considered within the framework of nonlocal electrostatics. The dipolar-surface layers are modelled as regular lattices with fixed orientation of dipoles which are immersed into the solvent; solvent response is characterized by nonlocal dielectric function. The model is elaborated in order to reveal the role of the dypolar-layer discreteness in the electric field produced by one surface and the interaction between two surfaces (which gives rise to the so-called ''hydration'' or ''structural'' force acting between mineral surfaces and phospholipid bilayers). The discreteness effects are present only for commensurate lattices. Their special mutual arrangement then may lead to considerable reduction of structural forces, viz. the usual repulsion regime may change at short distances to attraction. Conditions are considered when repulsion is entirely replaced by attraction, i.e. the ''hydration barrier'' disappears. In appended note it is discussed the role of solvation of surface dipolar groups. It is proposed an explanation of why two modes of decay (one with oscillative fine structure) may be present in the dependence of the force upon distance, if the surface dipolar groups are immersed deep enough in the solvent, and how the long-range oscillative mode disappears when the surface is but weakly solvated

  17. Conformation Analysis of T1 Lipase on Alcohols Solvent using Molecular Dynamics Simulation

    Science.gov (United States)

    Putri, A. M.; Sumaryada, T.; Wahyudi, S. T.

    2017-07-01

    Biodiesel usually is produced commercially via a transesterification reaction of vegetable oil with alcohol and alkali catalyst. The alkali catalyst has some drawbacks, such as the soap formation during the reaction. T1 Lipase enzyme had been known as a thermostable biocatalyst which is able to produce biodiesel through a cleaner process. In this paper the performance of T1 lipase enzyme as catalyst for transesterification reaction in pure ethanol, methanol, and water solvents were studied using a Molecular Dynamics (MD) Simulation at temperature of 300 K for 10 nanoseconds. The results have shown that in general the conformation of T1 lipase enzyme in methanol is more dynamics as shown by the value of root mean square deviation (RMSD), root mean squared fluctuation (RMSF), and radius of gyration. The highest solvent accessible surface area (SASA) total was also found in methanol due to the contribution of non-polar amino acid in the interior of the protein. Analysis of MD simulation has also revealed that the enzyme structure tend to be more rigid in ethanol environment. The analysis of electrostatic interactions have shown that Glu359-Arg270 salt-bridge pair might hold the key of thermostability of T1 lipase enzyme as shown by its strong and stable binding in all three solvents.

  18. Canyon solvent cleaning with solid adsorbents

    International Nuclear Information System (INIS)

    Reif, D.J.

    1987-01-01

    The HM Process at the Savannah River Plant (SRP) uses 7.5% tributyl phosphate in n-paraffin as an extraction solvent. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials that influence product losses, product decontamination, and separation efficiencies. Laboratory studies to improve online solvent cleaning have shown that carbonate washing, although removing residual solvent activity, does not remove binding ligands that hold fission products in the solvent. Treatment of solvent with a solid adsorbent removes binding ligands and significantly improves recycle solvent performance. Both laboratory work defining a full-scale adsorption process and the use of the process to clean HM Process first cycle solvent are presented

  19. Substitution of Organic Solvents - a Way to improve Working Environment and reduce Emissions to the Atmosphere

    DEFF Research Database (Denmark)

    Jacobsen, Thomas

    1996-01-01

    solvents as cleaning agents has been reached. However, some barriers to this substitution process, are found outside the printing companies. In designing of machines and auxiliary equipment, the manufacturers must take into account, that cleaning with non-volatile agents should be possible. Even a rather...... the process in order to omit the solvents or to use water-based products. In cases, where a change to water-based is not evident, improvements can be reached by using non-volatile, low-toxic products, typically esters of fatty acids from vegetable oils. In offset printing a drastic reduction of use of organic...

  20. Next Generation Solvent Performance in the Modular Caustic Side Solvent Extraction Process - 15495

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Tara E. [Savannah River Remediation, LLC., Aiken, SC (United States); Scherman, Carl [Savannah River Remediation, LLC., Aiken, SC (United States); Martin, David [Savannah River Remediation, LLC., Aiken, SC (United States); Suggs, Patricia [Savannah River Site (SRS), Aiken, SC (United States)

    2015-01-14

    Changes to the Modular Caustic Side Solvent Extraction Unit (MCU) flow-sheet were implemented in the facility. Implementation included changing the scrub and strip chemicals and concentrations, modifying the O/A ratios for the strip, scrub, and extraction contactor banks, and blending the current BoBCalixC6 extractant-based solvent in MCU with clean MaxCalix extractant-based solvent. During the successful demonstration period, the MCU process was subject to rigorous oversight to ensure hydraulic stability and chemical/radionuclide analysis of the key process tanks (caustic wash tank, solvent hold tank, strip effluent hold tank, and decontaminated salt solution hold tank) to evaluate solvent carryover to downstream facilities and the effectiveness of cesium removal from the liquid salt waste. Results indicated the extraction of cesium was significantly more effective with an average Decontamination Factor (DF) of 1,129 (range was 107 to 1,824) and that stripping was effective. The contactor hydraulic performance was stable and satisfactory, as indicated by contactor vibration, contactor rotational speed, and flow stability; all of which remained at or near target values. Furthermore, the Solvent Hold Tank (SHT) level and specific gravity was as expected, indicating that solvent integrity and organic hydraulic stability were maintained. The coalescer performances were in the range of processing results under the BOBCalixC6 flow sheet, indicating negligible adverse impact of NGS deployment. After the Demonstration period, MCU began processing via routine operations. Results to date reiterate the enhanced cesium extraction and stripping capability of the Next Generation Solvent (NGS) flow sheet. This paper presents process performance results of the NGS Demonstration and continued operations of MCU utilizing the blended BobCalixC6-MaxCalix solvent under the NGS flowsheet.

  1. Purex process solvent: literature review

    International Nuclear Information System (INIS)

    Geier, R.G.

    1979-10-01

    This document summarizes the data on Purex process solvent presently published in a variety of sources. Extracts from these various sources are presented herein and contain the work done, the salient results obtained, and the original, unaltered conclusions of the author of each paper. Three major areas are addressed: solvent stability, solvent quality testing, and solvent treatment processes. 34 references, 44 tables

  2. Purex process solvent: literature review

    Energy Technology Data Exchange (ETDEWEB)

    Geier, R.G.

    1979-10-01

    This document summarizes the data on Purex process solvent presently published in a variety of sources. Extracts from these various sources are presented herein and contain the work done, the salient results obtained, and the original, unaltered conclusions of the author of each paper. Three major areas are addressed: solvent stability, solvent quality testing, and solvent treatment processes. 34 references, 44 tables.

  3. Heavy Atom Substituents as Molecular Probes for Solvent Effects on the Dynamics of Short-lived Triplet Exciplexes

    OpenAIRE

    Winter, Gerhard; Steiner, Ulrich

    1980-01-01

    The influence of heavy atom substituents (Br, I) in the electron donor aniline on the electron transfer reaction with thiopyronine triplet is investigated by flash spectroscopy in solvents of different viscosity and polarity. Triplet quenching constants and radical yields are determined. The results are analysed in terms of decay constants of an intermediate triplet exciplex where the heavy atom substituents significantly enhance the intersystem crossing process leading to singlet ground stat...

  4. Comparative Assessment of Nonlocal Continuum Solvent Models Exhibiting Overscreening

    Directory of Open Access Journals (Sweden)

    Ren Baihua

    2017-01-01

    Full Text Available Nonlocal continua have been proposed to offer a more realistic model for the electrostatic response of solutions such as the electrolyte solvents prominent in biology and electrochemistry. In this work, we review three nonlocal models based on the Landau-Ginzburg framework which have been proposed but not directly compared previously, due to different expressions of the nonlocal constitutive relationship. To understand the relationships between these models and the underlying physical insights from which they are derive, we situate these models into a single, unified Landau-Ginzburg framework. One of the models offers the capacity to interpret how temperature changes affect dielectric response, and we note that the variations with temperature are qualitatively reasonable even though predictions at ambient temperatures are not quantitatively in agreement with experiment. Two of these models correctly reproduce overscreening (oscillations between positive and negative polarization charge densities, and we observe small differences between them when we simulate the potential between parallel plates held at constant potential. These computations require reformulating the two models as coupled systems of local partial differential equations (PDEs, and we use spectral methods to discretize both problems. We propose further assessments to discriminate between the models, particularly in regards to establishing boundary conditions and comparing to explicit-solvent molecular dynamics simulations.

  5. A potentiometric study of molecular heteroconjugation equilibria in (n-butylamine+acetic acid) systems in binary (acetonitrile +1,4-dioxane) solvent mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Czaja, Malgorzata [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Makowski, Mariusz [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Chmurzynski, Lech [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)]. E-mail: lech@chem.univ.gda.pl

    2006-05-15

    By using the potentiometric method the following quantities have been determined: acidity constants of molecular acid, K{sub a}(HA), of cationic acid, K{sub a}(BH{sup +}), anionic and cationic homoconjugation constants, K{sub AHA{sup -}} and K{sub BHB{sup +}}, respectively, as well as molecular heteroconjugation constants, K{sub AHB}, in (n-butylamine+acetic acid) systems without proton transfer in binary (acetonitrile+1,4-dioxane), AN+D, solvent mixtures. The results of these measurements have shown that the magnitudes of the molecular heteroconjugation constants do not depend on the 1,4-dioxane content in the mixed solvent, i.e., on solvent polarity. It has also been found that in the (acid+base) systems without proton transfer, the manner of carrying out the titration (direct B+HA vs. reverse HA+B) does not affect the magnitudes of the molecular heteroconjugation constants.

  6. Polar bears and sea ice habitat change

    Science.gov (United States)

    Durner, George M.; Atwood, Todd C.; Butterworth, Andy

    2017-01-01

    The polar bear (Ursus maritimus) is an obligate apex predator of Arctic sea ice and as such can be affected by climate warming-induced changes in the extent and composition of pack ice and its impacts on their seal prey. Sea ice declines have negatively impacted some polar bear subpopulations through reduced energy input because of loss of hunting habitats, higher energy costs due to greater ice drift, ice fracturing and open water, and ultimately greater challenges to recruit young. Projections made from the output of global climate models suggest that polar bears in peripheral Arctic and sub-Arctic seas will be reduced in numbers or become extirpated by the end of the twenty-first century if the rate of climate warming continues on its present trajectory. The same projections also suggest that polar bears may persist in the high-latitude Arctic where heavy multiyear sea ice that has been typical in that region is being replaced by thinner annual ice. Underlying physical and biological oceanography provides clues as to why polar bear in some regions are negatively impacted, while bears in other regions have shown no apparent changes. However, continued declines in sea ice will eventually challenge the survival of polar bears and efforts to conserve them in all regions of the Arctic.

  7. Process for removing halogenated aliphatic and aromatic compounds from petroleum products

    Science.gov (United States)

    Googin, J.M.; Napier, J.M.; Travaglini, M.A.

    1983-09-20

    A process is described for removing halogenated aliphatic and aromatic compounds, e.g., polychlorinated biphenyls, from petroleum products by solvent extraction. The halogenated aliphatic and aromatic compounds are extracted from a petroleum product into a polar solvent by contacting the petroleum product with the polar solvent. The polar solvent is characterized by a high solubility for the extracted halogenated aliphatic and aromatic compounds, a low solubility for the petroleum product and considerable solvent power for polyhydroxy compound. The preferred polar solvent is dimethylformamide. A miscible compound, such as, water or a polyhydroxy compound, is added to the polar extraction solvent to increase the polarity of the polar extraction solvent. The halogenated aliphatic and aromatic compounds are extracted from the highly-polarized mixture of water or polyhydroxy compound and polar extraction solvent into a low polar or nonpolar solvent by contacting the water or polyhydroxy compound-polar solvent mixture with the low polar or nonpolar solvent. The halogenated aliphatic and aromatic compounds and the low polar or nonpolar solvent are separated by physical means, e.g., vacuum evaporation. The polar and nonpolar solvents are recovered from recycling. The process can easily be designed for continuous operation. Advantages of the process include that the polar solvent and a major portion of the nonpolar solvent can be recycled, the petroleum products are reclaimable and the cost for disposing of waste containing polychlorinated biphenyls is significantly reduced. 1 fig.

  8. Low Operational Stability of Enzymes in Dry Organic Solvents: Changes in the Active Site Might Affect Catalysis

    Directory of Open Access Journals (Sweden)

    Gabriel Barletta

    2012-02-01

    Full Text Available The potential of enzyme catalysis in organic solvents for synthetic applications has been overshadowed by the fact that their catalytic properties are affected by organic solvents. In addition, it has recently been shown that an enzyme’s initial activity diminishes considerably after prolonged exposure to organic media. Studies geared towards understanding this last drawback have yielded unclear results. In the present work we decided to use electron paramagnetic resonance spectroscopy (EPR to study the motion of an active site spin label (a nitroxide free radical during 96 h of exposure of the serine protease subtilisin Carlsberg to four different organic solvents. Our EPR data shows a typical two component spectra that was quantified by the ratio of the anisotropic and isotropic signals. The isotropic component, associated with a mobile nitroxide free radical, increases during prolonged exposure to all solvents used in the study. The maximum increase (of 43% was observed in 1,4-dioxane. Based on these and previous studies we suggest that prolonged exposure of the enzyme to these solvents provokes a cascade of events that could induce substrates to adopt different binding conformations. This is the first EPR study of the motion of an active-site spin label during prolonged exposure of an enzyme to organic solvents ever reported.

  9. Solubility of sulfur compounds in commercial physical solvents and an ionic liquid from Monte Carlo simulations

    NARCIS (Netherlands)

    Jamali, S.H.; Ramdin, M.; Becker, T.M.; Torres-Knoop, Ariana; Dubbeldam, D.; Buijs, W.; Vlugt, T.J.H.

    2017-01-01

    Natural gas, synthesis gas, and flue gas typically contain a large number of impurities (e.g., acidic gases), which should be removed to avoid environmental and technological problems, and to meet customer specifications. One approach is to use physical solvents to remove the acidic gases. If no

  10. Solvent/non-solvent sintering: a novel route to create porous microsphere scaffolds for tissue regeneration.

    Science.gov (United States)

    Brown, Justin L; Nair, Lakshmi S; Laurencin, Cato T

    2008-08-01

    Solvent/non-solvent sintering creates porous polymeric microsphere scaffolds suitable for tissue engineering purposes with control over the resulting porosity, average pore diameter, and mechanical properties. Five different biodegradable biocompatible polyphosphazenes exhibiting glass transition temperatures from -8 to 41 degrees C and poly (lactide-co-glycolide), (PLAGA) a degradable polymer used in a number of biomedical settings, were examined to study the versatility of the process and benchmark the process to heat sintering. Parameters such as: solvent/non-solvent sintering solution composition and submersion time effect the sintering process. PLAGA microsphere scaffolds fabricated with solvent/non-solvent sintering exhibited an interconnected porosity and pore size of 31.9% and 179.1 mum, respectively which was analogous to that of conventional heat sintered PLAGA microsphere scaffolds. Biodegradable polyphosphazene microsphere scaffolds exhibited a maximum interconnected porosity of 37.6% and a maximum compressive modulus of 94.3 MPa. Solvent/non-solvent sintering is an effective strategy for sintering polymeric microspheres, with a broad spectrum of glass transition temperatures, under ambient conditions making it an excellent fabrication route for developing tissue engineering scaffolds and drug delivery vehicles. (c) 2007 Wiley Periodicals, Inc.

  11. Measurement and correlation of solubility of cefmenoxime hydrochloride in pure solvents and binary solvent mixtures

    International Nuclear Information System (INIS)

    Wang, Jinxiu; Xie, Chuang; Yin, Qiuxiang; Tao, Linggang; Lv, Jun; Wang, Yongli; He, Fang; Hao, Hongxun

    2016-01-01

    Highlights: • Solubility of cefmenoxime hydrochloride in pure and binary solvents was determined. • The experimental solubility data were correlated by thermodynamic models. • A model was employed to calculate the melting temperature of cefmenoxime hydrochloride. • Mixing thermodynamic properties of cefmenoxime hydrochloride were calculated. - Abstract: The solubility of cefmenoxime hydrochloride in pure solvents and binary solvent mixtures was measured at temperatures from (283.15 to 313.15) K by using the UV spectroscopic method. The results reveal that the solubility of cefmenoxime hydrochloride increases with increasing temperature in all solvent selected. The solubility of cefmenoxime hydrochloride reaches its maximum value when the mole fraction of isopropanol is 0.2 in the binary solvent mixtures of (isopropanol + water). The modified Apelblat equation and the NRTL model were successfully used to correlate the experimental solubility in pure solvents while the modified Apelblat equation, the CNIBS/R–K model and the Jouyban–Acree model were applied to correlate the solubility in binary solvent mixtures. In addition, the mixing thermodynamic properties of cefmenoxime hydrochloride in different solvents were also calculated based on the NRTL model and experimental solubility data.

  12. Measurement and prediction of dabigatran etexilate mesylate Form II solubility in mono-solvents and mixed solvents

    International Nuclear Information System (INIS)

    Xiao, Yan; Wang, Jingkang; Wang, Ting; Ouyang, Jinbo; Huang, Xin; Hao, Hongxun; Bao, Ying; Fang, Wen; Yin, Qiuxiang

    2016-01-01

    Highlights: • Solubility of DEM Form II in mono-solvents and binary solvent mixtures was measured. • Regressed UNIFAC model was used to predict the solubility in solvent mixtures. • The experimental solubility data were correlated by different models. - Abstract: UV spectrometer method was used to measure the solubility data of dabigatran etexilate mesylate (DEM) Form II in five mono-solvents (methanol, ethanol, ethane-1,2-diol, DMF, DMAC) and binary solvent mixtures of methanol and ethanol in the temperature range from 287.37 K to 323.39 K. The experimental solubility data in mono-solvents were correlated with modified Apelblat equation, van’t Hoff equation and λh equation. GSM model and Modified Jouyban-Acree model were employed to correlate the solubility data in mixed solvent systems. And Regressed UNIFAC model was used to predict the solubility of DEM Form II in the binary solvent mixtures. Results showed that the predicted data were consistent with the experimental data.

  13. Polarity Control in Group-III Nitrides beyond Pragmatism

    Science.gov (United States)

    Mohn, Stefan; Stolyarchuk, Natalia; Markurt, Toni; Kirste, Ronny; Hoffmann, Marc P.; Collazo, Ramón; Courville, Aimeric; Di Felice, Rosa; Sitar, Zlatko; Vennéguès, Philippe; Albrecht, Martin

    2016-05-01

    Controlling the polarity of polar semiconductors on nonpolar substrates offers a wealth of device concepts in the form of heteropolar junctions. A key to realize such structures is an appropriate buffer-layer design that, in the past, has been developed by empiricism. GaN or ZnO on sapphire are prominent examples for that. Understanding the basic processes that mediate polarity, however, is still an unsolved problem. In this work, we study the structure of buffer layers for group-III nitrides on sapphire by transmission electron microscopy as an example. We show that it is the conversion of the sapphire surface into a rhombohedral aluminum-oxynitride layer that converts the initial N-polar surface to Al polarity. With the various AlxOyNz phases of the pseudobinary Al2O3 -AlN system and their tolerance against intrinsic defects, typical for oxides, a smooth transition between the octahedrally coordinated Al in the sapphire and the tetrahedrally coordinated Al in AlN becomes feasible. Based on these results, we discuss the consequences for achieving either polarity and shed light on widely applied concepts in the field of group-III nitrides like nitridation and low-temperature buffer layers.

  14. Proton triggered circularly polarized luminescence in orthogonal- and co-assemblies of chiral gelators with achiral perylene bisimide.

    Science.gov (United States)

    Han, Dongxue; Han, Jianlei; Huo, Shengwei; Qu, Zuoming; Jiao, Tifeng; Liu, Minghua; Duan, Pengfei

    2018-05-29

    The orthogonal- or co-assembly of achiral perylene bisimide (PBI) with chiral gelators can be regulated by solvents. While the coassembly leads to the formation of chiroptical nanofibers through chirality transfer, the orthogonal assemblies could not. Moreover, protonation on the coassembled nanofibers could light up the circularly polarized luminescence (CPL).

  15. Detecting Changing Polarization Structures in Sagittarius A* with High Frequency VLBI

    Science.gov (United States)

    Fish, Vincent L.; Doeleman, Sheperd S.; Broderick, Avery E.; Loeb, Abraham; Rogers, Alan E. E.

    2009-12-01

    Sagittarius A* is the source of near infrared, X-ray, radio, and (sub)millimeter emission associated with the supermassive black hole at the Galactic Center. In the submillimeter regime, Sgr A* exhibits time-variable linear polarization on timescales corresponding to errors. Although the source-integrated linear polarization fraction in the models is typically only a few percent, the linear polarization fraction on small angular scales can be much higher, enabling the detection of changes in the polarimetric structure of Sgr A* on a wide variety of baselines. The shortest baselines track the source-integrated linear polarization fraction, while longer baselines are sensitive to polarization substructures that are beam-diluted by connected-element interferometry. The detection of periodic variability in source polarization should not be significantly affected even if instrumental polarization terms cannot be calibrated out. As more antennas are included in the (sub)millimeter-VLBI array, observations with full polarization will provide important new diagnostics to help disentangle intrinsic source polarization from Faraday rotation effects in the accretion and outflow region close to the black hole event horizon.

  16. Antimicrobial Activity Investigation on Wuyiencin Fractions of Different Polarity

    Directory of Open Access Journals (Sweden)

    Zengjie Cui

    2010-04-01

    Full Text Available The aim of this study was to evaluate the antimicrobial activity of Wuyiencin fractions with different polarities against six indicator microorganisms: Rhodotorula rubra, Bacillus subtilis, Bacillus megaterium, Escherichia coli, Cladosporium fulvum and Staphylococcus aureus. The fermentation broth of Wuyiencin was submitted to AB-8 macroporous adsorptive resin and fractionated with solvents of different polarity. The fraction eluted with water had remarkably antimicrobial activity against all the microorganisms investigated except for C. fulvum and S. aureus (MIC ≤ 0.0625 mg/mL, probably due to the presence of active components. The fraction eluted with methanol showed potential antimicrobial activity against all the test microorganisms except for R.rubra, with MIC values of0.5 and 2 mg/mL. In conclusion, fractions eluted with water and methanol, respectively, represent the main active-part of Wuyiencin, and could be emphasized for agricultural applications in the future.

  17. Lattice-polarity-driven epitaxy of hexagonal semiconductor nanowires

    KAUST Repository

    Wang, Ping

    2015-12-22

    Lattice-polarity-driven epitaxy of hexagonal semiconductor nanowires (NWs) is demonstrated on InN NWs. In-polarity InN NWs form typical hexagonal structure with pyramidal growth front, whereas N-polarity InN NWs slowly turn to the shape of hexagonal pyramid and then convert to an inverted pyramid growth, forming diagonal pyramids with flat surfaces and finally coalescence with each other. This contrary growth behavior driven by lattice-polarity is most likely due to the relatively lower growth rate of the (0001 ̅) plane, which results from the fact that the diffusion barriers of In and N adatoms on the (0001) plane (0.18 and 1.0 eV, respectively) are about two-fold larger in magnitude than those on the (0001 ̅) plane (0.07 and 0.52 eV), as calculated by first-principles density functional theory (DFT). The formation of diagonal pyramids for the N-polarity hexagonal NWs affords a novel way to locate quantum dot in the kink position, suggesting a new recipe for the fabrication of dot-based devices.

  18. Solvent extraction process development for high plutonium fuel cycles

    Energy Technology Data Exchange (ETDEWEB)

    Anil Kumar, R; Selvaraj, P G; Natarajan, R; Raman, V R [Reprocessing Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    1994-06-01

    The purification of high plutonium bearing irradiated fuels using 30% TBP in dodecane diluent requires precise determination of concentration profiles during steady state, transient and process upset conditions. Mathematical models have been developed and a computer code is in use for determining Pu-U concentration profiles in a solvent extraction equipment in a typical reprocessing plant. The process parameters have been optimised for recovery of U and Pu and decontamination from the fission products. This computer code is used to analyse the extraction flow sheets of fuels of two typical Pu-U compositions encountered in Indian fast breeder programme. The analysis include the effect of uncertainty in equilibrium condition prediction by the model and the variation of flows of streams during plant operation. The studies highlight the margin available to avoid second organic phase formation and adjustments required in the process flowsheet. (author). 7 refs., 7 figs., 2 tabs.

  19. J-aggregation, its impact on excited state dynamics and unique solvent effects on macroscopic assembly of a core-substituted naphthalenediimide

    KAUST Repository

    Kar, Haridas; Gehrig, Dominik W.; Laquai, Fré dé ric; Ghosh, Suhrit

    2015-01-01

    Herein we reveal a straightforward supramolecular design for the H-bonding driven J-aggregation of an amine-substituted cNDI in aliphatic hydrocarbons. Transient absorption spectroscopy reveals sub-ps intramolecular electron transfer in isolated NDI molecules in a THF solution followed by a fast recombination process, while a remarkable extension of the excited state lifetime by more than one order of magnitude occurred in methylcyclohexane likely owing to an increased charge-separation as a result of better delocalization of the charge-separated states in J-aggregates. We also describe unique solvent-effects on the macroscopic structure and morphology. While J-aggregation with similar photophysical characteristics was noticed in all the tested aliphatic hydrocarbons, the morphology strongly depends on the “structure” of the solvents. In linear hydrocarbons (n-hexane, n-octane, n-decane or n-dodecane), formation of an entangled fibrillar network leads to macroscopic gelation while in cyclic hydrocarbons (methylcyclohexane or cyclohexane) although having a similar polarity, the cNDI exhibits nanoscale spherical particles. These unprecedented solvent effects were rationalized by establishing structure-dependent specific interactions of the solvent molecules with the cNDI which may serve as a general guideline for solvent-induced morphology-control of structurally related self-assembled materials.

  20. J-aggregation, its impact on excited state dynamics and unique solvent effects on macroscopic assembly of a core-substituted naphthalenediimide

    KAUST Repository

    Kar, Haridas

    2015-03-12

    Herein we reveal a straightforward supramolecular design for the H-bonding driven J-aggregation of an amine-substituted cNDI in aliphatic hydrocarbons. Transient absorption spectroscopy reveals sub-ps intramolecular electron transfer in isolated NDI molecules in a THF solution followed by a fast recombination process, while a remarkable extension of the excited state lifetime by more than one order of magnitude occurred in methylcyclohexane likely owing to an increased charge-separation as a result of better delocalization of the charge-separated states in J-aggregates. We also describe unique solvent-effects on the macroscopic structure and morphology. While J-aggregation with similar photophysical characteristics was noticed in all the tested aliphatic hydrocarbons, the morphology strongly depends on the “structure” of the solvents. In linear hydrocarbons (n-hexane, n-octane, n-decane or n-dodecane), formation of an entangled fibrillar network leads to macroscopic gelation while in cyclic hydrocarbons (methylcyclohexane or cyclohexane) although having a similar polarity, the cNDI exhibits nanoscale spherical particles. These unprecedented solvent effects were rationalized by establishing structure-dependent specific interactions of the solvent molecules with the cNDI which may serve as a general guideline for solvent-induced morphology-control of structurally related self-assembled materials.

  1. Cesium Concentration in MCU Solvent

    International Nuclear Information System (INIS)

    Walker, D

    2006-01-01

    During Modular Caustic-Side Solvent Extraction (CSSX) Unit (MCU) operations, Cs-137 concentrations in product streams will vary depending on the location in the process and on the recent process conditions. Calculations of cesium concentrations under a variety of operating conditions reveal the following: (1) Under nominal operations with salt solution feed containing 1.1 Ci Cs-137 per gallon, the maximum Cs-137 concentration in the process will occur in the strip effluent (SE) and equal 15-16.5 Ci/gal. (2) Under these conditions, the majority of the solvent will contain 0.005 to 0.01 Ci/gal, with a limited portion of the solvent in the contactor stages containing ∼4 Ci/gal. (3) When operating conditions yield product near 0.1 Ci Cs-137/gal in the decontaminated salt solution (DSS), the SE cesium concentration will be the same or lower than in nominal operations, but majority of the stripped solvent will increase to ∼2-3 Ci/gal. (4) Deviations in strip and waste stream flow rates cause the largest variations in cesium content: (a) If strip flow rates deviate by -30% of nominal, the SE will contain ∼23 Ci/gal, although the cesium content of the solvent will increase to only 0.03 Ci/gal; (b) If strip flow rate deviates by -77% (i.e., 23% of nominal), the SE will contain 54 Ci/gal and solvent will contain 1.65 Ci/gal. At this point, the product DSS will just reach the limit of 0.1 Ci/gal, causing the DSS gamma monitors to alarm; and (c) Moderate (+10 to +30%) deviations in waste flow rate cause approximately proportional increases in the SE and solvent cesium concentrations. Recovery from a process failure due to poor cesium stripping can achieve any low cesium concentration required. Passing the solvent back through the contactors while recycling DSS product will produce a ∼70% reduction during one pass through the contactors (assuming the stripping D value is no worse than 0.36). If the solvent is returned to the solvent hold tank (containing additional

  2. Metasurface for multi-channel terahertz beam splitters and polarization rotators

    Science.gov (United States)

    Zang, XiaoFei; Gong, HanHong; Li, Zhen; Xie, JingYa; Cheng, QingQing; Chen, Lin; Shkurinov, Alexander P.; Zhu, YiMing; Zhuang, SongLin

    2018-04-01

    Terahertz beam splitters and polarization rotators are two typical devices with wide applications ranging from terahertz communication to system integration. However, they are faced with severe challenges in manipulating THz waves in multiple channels, which is desirable for system integration and device miniaturization. Here, we propose a method to design ultra-thin multi-channel THz beam splitters and polarization rotators simultaneously. The reflected beams are divided into four beams with nearly the same density under illumination of linear-polarized THz waves, while the polarization of reflected beams in each channel is modulated with a rotation angle or invariable with respect to the incident THz waves, leading to the multi-channel polarization rotator (multiple polarization rotation in the reflective channels) and beam splitter, respectively. Reflective metasurfaces, created by patterning metal-rods with different orientations on a polyimide film, were fabricated and measured to demonstrate these characteristics. The proposed approach provides an efficient way of controlling polarization of THz waves in various channels, which significantly simplifies THz functional devices and the experimental system.

  3. Effects of Reentry Plasma Sheath on GPS Patch Antenna Polarization Property

    Directory of Open Access Journals (Sweden)

    L. Zhao

    2013-01-01

    Full Text Available A plasma sheath enveloping a reentry vehicle would affect performances of on-board antenna greatly, especially the navigation antennas. This paper studies the effects of reentry plasma sheath on a GPS right-hand circularly polarized (RHCP patch antenna polarization property during a typical reentry process. Utilizing the algorithm of finite integration technique, the polarization characteristic of a GPS antenna coated by a plasma sheath is obtained. Results show that the GPS RHCP patch antenna radiation pattern distortions as well as polarization deteriorations exist during the entire reentry process, and the worst polarization mismatch loss between a GPS antenna and RHCP GPS signal is nearly 3 dB. This paper also indicates that measures should be taken to alleviate the plasma sheath for maintaining the GPS communication during the reentry process.

  4. π--induced single charge exchange on polarized 3He

    International Nuclear Information System (INIS)

    Zhao, Q.; Burleson, S.; Blanchard, T.

    1995-01-01

    Asymmetries, A y , for the (π - ,π 0 ) reaction on polarized 3 He were measured using the pion beam of the P3W channel at LAMPF. The π 0 were detected with the new Neutral Meson Spectrometer (NMS) in coincidence with recoiling tritons. The recoil detector consisted of scintillation-counter telescopes and a wire chamber that provided energy-loss and direction information, respectively. The polarized gaseous 3 He target developed at TRIUMF was modified and run with the use of two diode lasers. Polarizations were typically 50%. The A y taken at T π = 200 MeV between 60 and 105 degrees were found to be strongly angle-dependent. The results will be compared with the theoretical predictions

  5. The polarized proton and deuteron beam at the Bonn isochronous cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, K G; Enders, R; Hammon, W; Krause, K D; Lesemann, D; Scholzen, A [Bonn Univ. (F.R. Germany). Inst. fuer Angewandte Physik; Euler, K; Schueller, B [Bonn Univ. (F.R. Germany). Inst. fuer Strahlen- und Kernphysik

    1976-02-15

    The present state of the polarized proton and deuteron source at the Bonn cyclotron is described. The source, which is of the atomic beam type, gives typical ion beam intensities of 2 ..mu..A for protons and 3 ..mu..A for deuterons. The overall transmission from the source to the first stopper after extraction from the cyclotron is 3%. Target currents with an energy resolution E/..delta..E=500 are 20 nA for deuterons and 10 nA for protons. For the proton beam, a polarization P=-0.71 was measured. For the deuteron beam, a pure vector polarization Psub(z)=-0.47 or various mixtures of vector and tensor polarization are obtained.

  6. Iodine removing method in organic solvent

    International Nuclear Information System (INIS)

    Suzuki, Takeo; Sakurai, Manabu

    1988-01-01

    Purpose: To effectively remove iodine in an organic solvent to thereby remove iodine in the solvent that can be re-used or put to purning treatment. Method: Organic solvent formed from wastes of nuclear facilities is mixed with basic lead acetate, or silica gel or activated carbon incorporated with such a compound to adsorb iodine in the organic solvent to the basic lead acetate. Then, iodine in the organic solvent is removed by separating to eliminate the basic lead acetate adsorbing iodine from the organic solvent or by passing the organic solvent through a tower or column charged or pre-coated with silica gel or activated carbon incorporated with lead acetate. By using basic lead acetate as the adsorbents, iodine can effective by adsorbed and eliminated. Thus, the possibility of circumstantial release of iodine can be reduced upon reusing or burning treatment of the organic solvent. (Kamimura, M.)

  7. Sensibilidade do carrapato Boophilus microplus a solventes Sensibility of Boophilus microplus tick to solvents

    Directory of Open Access Journals (Sweden)

    Ana Carolina de Souza Chagas

    2003-02-01

    Full Text Available Os experimentos envolvendo o uso de acaricidas sintéticos ou naturais, geralmente necessitam da utilização de um solvente. Com a finalidade de verificar a sensibilidade do carrapato bovino Boophilus microplus a diferentes solventes, larvas e fêmeas ingurgitadas deste ectoparasito foram expostas a sete solventes em cinco diferentes concentrações, na ausência e presença de azeite de oliva. Os resultados mostraram que a utilização do azeite de oliva não produz resultados diferentes estatisticamente em testes de larvas com papel impregnado, fato não verificado em testes de imersão de adultos com compostos hidrofílicos. A mortalidade média causada pelos solventes foi menor nos testes com papel impregnado, aumentando nos testes de imersão de larvas e de adultos. Solventes de baixo peso molecular e pouca viscosidade como o álcool metílico e o álcool etílico, não interferiram na mortalidade média em testes biológicos de B. microplus, principalmente em concentrações inferiores a 76%.Experiments carried out with synthetic or natural acaricides usually use a solvent. To investigate the sensitivity of Boophilus microplus cattle tick to different solvents, larvae and engorged female were subjected to seven solvents in five different concentrations. It was done in the presence and absence of olive oil. The results showed that the utilization of olive oil doesn't produce different statistical results in impregnated paper larvae test. It did not happen in adults immersion test with hydrophilic compounds. The mean mortality caused by solvents was small in impregnated paper larvae test, increasing in immersion tests of larvae and adults. Solvents with low molecular weight and viscosity like ethyl alcohol and methyl alcohol did not cause interference in the mortality of B. microplus in biological tests, mainly in concentrations below 76%.

  8. Highly crystalline films of PCPDTBT with branched side chains by solvent vapor crystallization: influence on opto-electronic properties.

    Science.gov (United States)

    Fischer, Florian S U; Trefz, Daniel; Back, Justus; Kayunkid, Navaphun; Tornow, Benjamin; Albrecht, Steve; Yager, Kevin G; Singh, Gurpreet; Karim, Alamgir; Neher, Dieter; Brinkmann, Martin; Ludwigs, Sabine

    2015-02-18

    PCPDTBT, a marginally crystallizable polymer, is crystallized into a new crystal structure using solvent-vapor annealing. Highly ordered areas with three different polymer-chain orientations are identified using TEM/ED, GIWAXS, and polarized Raman spectroscopy. The optical and structural properties differ significantly from films prepared by standard device preparation protocols. Bilayer solar cells, however, show similar performance. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Next Generation Solvent Development for Caustic-Side Solvent Extraction of Cesium

    Energy Technology Data Exchange (ETDEWEB)

    Moyer, Bruce A. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Birdwell, Joseph F. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Bonnesen, Peter V. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Bruffey, Stephanie [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

    2014-03-01

    This report summarizes the FY 2010 and 2011 accomplishments at Oak Ridge National Laboratory (ORNL) in developing the Next Generation Caustic-Side Solvent Extraction (NG-CSSX) process, referred to commonly as the Next Generation Solvent (NGS), under funding from the U.S. Department of Energy, Office of Environmental Management (DOE-EM), Office of Technology Innovation and Development. The primary product of this effort is a process solvent and preliminary flowsheet capable of meeting a target decontamination factor (DF) of 40,000 for worst-case Savannah River Site (SRS) waste with a concentration factor of 15 or higher in the 18-stage equipment configuration of the SRS Modular Caustic-Side Solvent Extraction Unit (MCU). In addition, the NG-CSSX process may be readily adapted for use in the SRS Salt Waste Processing Facility (SWPF) or in supplemental tank-waste treatment at Hanford upon appropriate solvent or flowsheet modifications. Efforts in FY 2010 focused on developing a solvent composition and process flowsheet for MCU implementation. In FY 2011 accomplishments at ORNL involved a wide array of chemical-development activities and testing up through single-stage hydraulic and mass-transfer tests in 5-cm centrifugal contactors. Under subcontract from ORNL, Argonne National Laboratory (ANL) designed a preliminary flowsheet using ORNL cesium distribution data, and Tennessee Technological University confirmed a chemical model for cesium distribution ratios (DCs) as a function of feed composition. Inter laboratory efforts were coordinated with complementary engineering tests carried out (and reported separately) by personnel at Savannah River National Laboratory (SRNL) and Savannah River Remediation (SRR) with helpful advice by Parsons Engineering and General Atomics on aspects of possible SWPF implementation.

  10. Selection and design of solvents

    DEFF Research Database (Denmark)

    Gani, Rafiqul

    and design of solvents will be presented together with application examples. The selection problem is defined as finding known chemicals that match the desired functions of a solvent for a specified set of applications. The design problem is defined as finding the molecular structure (or mixture of molecules....... With increasing interest on issues such as waste, sustainability, environmental impact and green chemistry, the selection and design of solvents have become important problems that need to be addressed during chemical product-process design and development. Systematic methods and tools suitable for selection......) that match the desired functions of a solvent for a specified set of applications. Use of organic chemicals and ionic liquids as solvents will be covered....

  11. Enhanced mobility of poly(3-hexylthiophene) transistors by spin-coating from high-boiling-point solvents

    DEFF Research Database (Denmark)

    Chang, J.F.; Sun, B.Q.; Breiby, Dag Werner

    2004-01-01

    chloroform are typically on the order of 0.01 cm(2)/(V s). Here we investigate a range of solvents with higher boiling points. We find that 1,2,4-trichlorobenzene with good solubility and a high boiling point significantly improves the field-effect mobilities up to 0.12 cm(2)/(V s) with on:off ratios of 10...

  12. Immunomodulatory activities of different solvent extracts from Tricholoma matsutake (S. Ito et S. Imai) singer (higher basidiomycetes) on normal mice.

    Science.gov (United States)

    Yin, Xiulian; You, Qinghong; Jiang, Zhonghai

    2012-01-01

    The immunomodulatory activities of different solvent extracts from the culinary-medicinal mushroom Tricholoma matsutake were studied in vivo in normal mice. The extracts were prepared using different solvents in an order of increasing polarity. The immunomodulatory activities were investigated by measuring the thymus and spleen index, phagocytic rate of macrophage phagocytosis, delayed-type hypersensitivity, plaque-forming cell, and proliferation of splenocytes. Results demonstrated that water extract (WE) and n-butyl alcohol extract (BAE) of T. matsutake could enhance the immunity of mice significantly compared with the control group. Main components of WE and BAE were polysaccharides, proteins, and flavonoids; we presume that these may be the main immunomodulating and immuno-enhancing agents in T. matsutake.

  13. New solvent systems for gradient counter-current chromatography in separation of betanin and its derivatives from processed Beta vulgaris L. juice.

    Science.gov (United States)

    Spórna-Kucab, Aneta; Garrard, Ian; Ignatova, Svetlana; Wybraniec, Sławomir

    2015-02-06

    Betalains, natural plant pigments, are beneficial compounds due to their antioxidant and possible chemoprotective properties. A mixture of betalains: betanin/isobetanin, decarboxybetanins and neobetanin from processed red beet roots (Beta vulgaris L.) juice was separated in food-grade, gradient solvent systems using high-performance counter-current chromatography (HPCCC). The decarboxylated and dehydrogenated betanins were obtained by thermal degradation of betanin/isobetanin from processed B. vulgaris L. juice under mild conditions. Two solvent systems (differing in their composition by phosphoric acid and ethanol volume gradient) consisting of BuOH-EtOH-NaClsolution-H2O-H3PO4 (v/v/v/v/v, 1300:200-1000:1300:700:2.5-10) in the 'tail-to-head' mode were run. The flow rate of the mobile phase (organic phase) was 1.0 or 2.0 ml/min and the column rotation speed was 1,600 rpm (20°C). The retention of the solvent system stationary phase (aqueous phase) was ca. 80%. The system with the acid and ethanol volume gradient consisting of BuOH-EtOH-NaClsolution-H2O-H3PO4 (v/v/v/v/v, 1300:200-240:1300:700:2.5-4.5) pumped at 2.0 ml/min was the most effective for a separation of betanin/isobetanin, 17-decarboxy-betanin/-isobetanin, 2-decarboxy-betanin/-isobetanin, 2,17-bidecarboxy-betanin/-isobetanin pairs as well as neobetanin. The pigments were detected by LC-DAD and LC-MS. The results are crucial in the application of completely food-grade solvent systems in separation of food-grade compounds as well, and the systems can possibly be extended to other ionizable and polar compounds with potential health benefits. In particular, the method is applicable for the isolation and purification of betalains present in such rich sources as B. vulgaris L. roots as well as cacti fruits and Amaranthaceae flowering plants due to modification possibilities of the solvent systems polarity. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. d-PET-controlled “off-on” Polarity-sensitive Probes for Reporting Local Hydrophilicity within Lysosomes

    Science.gov (United States)

    Zhu, Hao; Fan, Jiangli; Mu, Huiying; Zhu, Tao; Zhang, Zhen; Du, Jianjun; Peng, Xiaojun

    2016-10-01

    Polarity-sensitive fluorescent probes are powerful chemical tools for studying biomolecular structures and activities both in vitro and in vivo. However, the lack of “off-on” polarity-sensing probes has limited the accurate monitoring of biological processes that involve an increase in local hydrophilicity. Here, we design and synthesize a series of “off-on” polarity-sensitive fluorescent probes BP series consisting of the difluoroboron dippyomethene (BODIPY) fluorophore connected to a quaternary ammonium moiety via different carbon linkers. All these probes showed low fluorescence quantum yields in nonpolar solution but became highly fluorescent in polar media. BP-2, which contains a two-carbon linker and a trimethyl quaternary ammonium, displayed a fluorescence intensity and quantum yield that were both linearly correlated with solvent polarity. In addition, BP-2 exhibited high sensitivity and selectivity for polarity over other environmental factors and a variety of biologically relevant species. BP-2 can be synthesized readily via an unusual Mannich reaction followed by methylation. Using electrochemistry combined with theoretical calculations, we demonstrated that the “off-on” sensing behavior of BP-2 is primarily due to the polarity-dependent donor-excited photoinduced electron transfer (d-PET) effect. Live-cell imaging established that BP-2 enables the detection of local hydrophilicity within lysosomes under conditions of lysosomal dysfunction.

  15. Hazardous solvent substitution

    International Nuclear Information System (INIS)

    Twitchell, K.E.

    1995-01-01

    This article is an overview of efforts at INEL to reduce the generation of hazardous wastes through the elimination of hazardous solvents. To aid in their efforts, a number of databases have been developed and will become a part of an Integrated Solvent Substitution Data System. This latter data system will be accessible through Internet

  16. Organic Solvent Tropical Report

    International Nuclear Information System (INIS)

    COWLEY, W.L.

    2000-01-01

    This report provides the basis for closing the organic solvent safety issue. Sufficient information is presented to conclude that risk posed by an unmitigated organic solvent fire is within risk evaluation guidelines

  17. Role of α-Helical Structure in Organic Solvent-Activated Homodimer of Elastase Strain K

    Directory of Open Access Journals (Sweden)

    Chee Fah Wong

    2011-09-01

    Full Text Available Recombinant elastase strain K overexpressed from E. coli KRX/pCon2(3 was purified to homogeneity by a combination of hydrophobic interaction chromatography and ion exchange chromatography, with a final yield of 48% and a 25-fold increase in specific activity. The purified protein had exhibited a first ever reported homodimer size of 65 kDa by SDS-PAGE and MALDI-TOF, a size which is totally distinct from that of typically reported 33 kDa monomer from P. aeruginosa. The organic solvent stability experiment had demonstrated a stability pattern which completely opposed the rules laid out in previous reports in which activity stability and enhancement were observed in hydrophilic organic solvents such as DMSO, methanol, ethanol and 1-propanol. The high stability and enhancement of the enzyme in hydrophilic solvents were explained from the view of alteration in secondary structures. Elastinolytic activation and stability were observed in 25 and 50% of methanol, respectively, despite slight reduction in α-helical structure caused upon the addition of the solvent. Further characterization experiments had postulated great stability and enhancement of elastase strain K in broad range of temperatures, pHs, metal ions, surfactants, denaturing agents and substrate specificity, indicating its potential application in detergent formulation.

  18. Spectral simulations of polar diatomic molecules immersed in He clusters: application to the ICl (X) molecule

    International Nuclear Information System (INIS)

    Villarreal, P; Lara-Castells, M P de; Prosmiti, R; Delgado-Barrio, G; Lopez-Duran, D; Gianturco, F A; Jellinek, J

    2007-01-01

    A recently developed quantum-chemistry-like methodology to study molecules solvated in atomic clusters is applied to the ICl (iodine chloride) polar diatomic molecule immersed in clusters of He atoms. The atoms of the solvent clusters are treated as the 'electrons' and the solvated molecule as a structured 'nucleus' of the combined solvent-solute system. The helium-helium and helium-dopant interactions are represented by parametrized two-body and ab initio three-body potentials, respectively. The ground-state wavefunctions are used to compute the infrared (IR) spectra of the solvated molecule. In agreement with the experimental observations, the computed spectra exhibit considerable differences depending on whether the solvent cluster is comprised of bosonic ( 4 He) or fermionic ( 3 He) atoms. The source of these differences is attributed to the different spin-statistics of the solvent clusters. The bosonic versus fermionic nature of the solvent is reflected in the IR absorption selection rules. Only P and R branches with single state transitions appear in the spectrum when the molecule is solvated in a bosonic cluster. On the other hand, when the solvent represents a fermionic environment, quasi-degenerate multiplets of spin states contribute to each branch and, in addition, the Q-branch becomes also allowed. Combined, these two factors explain the more congested nature of the spectrum in the fermionic case

  19. Contribution of vitamin K1 to the electron spin polarization in spinach photosystem I

    International Nuclear Information System (INIS)

    Rustandi, R.R.; Snyder, S.W.; Feezel, L.L.; Michalski, T.J.; Norris, J.R.; Thurnauer, M.C.; Biggins, J.

    1990-01-01

    The electron spin polarized (ESP) electron paramagnetic resonance (EPR) signal observed in spinach photosystem I (PSI) particles was examined in preparations depleted of vitamin K1 by solvent extraction and following biological reconstitution by the quinone. The ESP EPR signal was not detected in the solvent-extracted PSI sample but was restored upon reconstitution with either protonated or deuterated vitamin K1 under conditions that also restored electron transfer to the terminal PSI acceptors. Reconstitution using deuterated vitamin K1 resulted in a line narrowing of the ESP EPR signal, supporting the conclusion that the ESP EPR signals in the reconstituted samples arise from a radical pair consisting of the oxidized PSI primary donor, P700+, and reduced vitamin K1

  20. Total milk fat extraction and quantification of polar and neutral lipids of cow, goat, and ewe milk by using a pressurized liquid system and chromatographic techniques.

    Science.gov (United States)

    Castro-Gómez, M P; Rodriguez-Alcalá, L M; Calvo, M V; Romero, J; Mendiola, J A; Ibañez, E; Fontecha, J

    2014-11-01

    Although milk polar lipids such as phospholipids and sphingolipids located in the milk fat globule membrane constitute 0.1 to 1% of the total milk fat, those lipid fractions are gaining increasing interest because of their potential beneficial effects on human health and technological properties. In this context, the accurate quantification of the milk polar lipids is crucial for comparison of different milk species, products, or dairy treatments. Although the official International Organization for Standardization-International Dairy Federation method for milk lipid extraction gives satisfactory results for neutral lipids, it has important disadvantages in terms of polar lipid losses. Other methods using mixtures of solvents such as chloroform:methanol are highly efficient for extracting polar lipids but are also associated with low sample throughput, long time, and large solvent consumption. As an alternative, we have optimized the milk fat extraction yield by using a pressurized liquid extraction (PLE) method at different temperatures and times in comparison with those traditional lipid extraction procedures using 2:1 chloroform:methanol as a mixture of solvents. Comparison of classical extraction methods with the developed PLE procedure were carried out using raw whole milk from different species (cows, ewes, and goats) and considering fat yield, fatty acid methyl ester composition, triacylglyceride species, cholesterol content, and lipid class compositions, with special attention to polar lipids such as phospholipids and sphingolipids. The developed PLE procedure was validated for milk fat extraction and the results show that this method performs a complete or close to complete extraction of all lipid classes and in less time than the official and Folch methods. In conclusion, the PLE method optimized in this study could be an alternative to carry out milk fat extraction as a routine method. Copyright © 2014 American Dairy Science Association. Published by

  1. Scenarios Evaluation Tool for Chlorinated Solvent MNA

    Energy Technology Data Exchange (ETDEWEB)

    Vangelas, Karen; Michael J. Truex; Charles J. Newell; Brian Looney

    2007-02-28

    Over the past three decades, much progress has been made in the remediation of chlorinated solvents from the subsurface. Yet these pervasive contaminants continue to present a significant challenge to the U.S. Department of Energy (DOE), other federal agencies, and other public and private organizations. The physical and chemical properties of chlorinated solvents make it difficult to rapidly reach the low concentrations typically set as regulatory limits. These technical challenges often result in high costs and long remediation time frames. In 2003, the DOE through the Office of Environmental Management funded a science-based technical project that uses the U.S. Environmental Protection Agency's technical protocol (EPA, 1998) and directives (EPA, 1999) on Monitored Natural Attenuation (MNA) as the foundation on which to introduce supporting concepts and new scientific developments that will support remediation of chlorinated solvents based on natural attenuation processes. This project supports the direction in which many site owners want to move to complete the remediation of their site(s), that being to complete the active treatment portion of the remedial effort and transition into MNA. The overarching objective of the effort was to examine environmental remedies that are based on natural processes--remedies such as Monitored Natural Attenuation (MNA) or Enhanced Attenuation (EA). The research program did identify several specific opportunities for advances based on: (1) mass balance as the central framework for attenuation based remedies, (2) scientific advancements and achievements during the past ten years, (3) regulatory and policy development and real-world experience using MNA, and (4) exploration of various ideas for integrating attenuation remedies into a systematic set of ''combined remedies'' for contaminated sites. These opportunities are summarized herein and are addressed in more detail in referenced project documents and

  2. Polarized Neutron Reflectometry of Nickel Corrosion Inhibitors.

    Science.gov (United States)

    Wood, Mary H; Welbourn, Rebecca J L; Zarbakhsh, Ali; Gutfreund, Philipp; Clarke, Stuart M

    2015-06-30

    Polarized neutron reflectometry has been used to investigate the detailed adsorption behavior and corrosion inhibition mechanism of two surfactants on a nickel surface under acidic conditions. Both the corrosion of the nickel surface and the structure of the adsorbed surfactant layer could be monitored in situ by the use of different solvent contrasts. Layer thicknesses and roughnesses were evaluated over a range of pH values, showing distinctly the superior corrosion inhibition of one negatively charged surfactant (sodium dodecyl sulfate) compared to a positively charged example (dodecyl trimethylammonium bromide) due to its stronger binding interaction with the surface. It was found that adequate corrosion inhibition occurs at significantly less than full surface coverage.

  3. Insecticide solvents: interference with insecticidal action.

    Science.gov (United States)

    Brattsten, L B; Wilkinson, C F

    1977-06-10

    Several commercial solvent mixtures commonly used as insecticide carriers in spray formulations increase by more than threefold the microsomal N-demethylation of p-chloro N-methylaniline in midgut preparations of southern army-worm (Spodoptera eridania) larvae exposed orally to the test solvents. Under laboratory conditions, the same solvent mixtures exhibit a protective action against the in vivo toxicity of the insecticide carbaryl to the larvae. The data are discussed with respect to possible solvent-insecticide interactions occurring under field conditions and, more broadly, to potential toxicological hazards of these solvents to humans.

  4. Reduction of cross-polarized reflection to enhance dual-band absorption

    Science.gov (United States)

    Kundu, Debidas; Mohan, Akhilesh; Chakrabarty, Ajay

    2016-11-01

    In this paper, cross-polarized reflection from a periodic array of metal-dielectric-metal resonator units is reduced to improve its absorbing performance. Through this simple and typical example, it is shown that some reported absorbers are actually poor absorbers but efficient polarization converters, when the cross-polarized reflection is considered. Using a frequency selective surface, sandwiched between the top layer and the ground plane, the cross-polarized reflection is reduced by 7.2 dB at 5.672 GHz and 8.5 dB at 9.56 GHz, while negligibly affecting the co-polarized reflection reduction performance. The polarization conversion ratio is reduced from 90. 74% to 34.12% and 98.51% to 27.2% and total absorption is improved up to 80% from 26% and 21% around the two resonant frequencies. The reflection characteristics of the proposed absorber are quantitatively analyzed using interference theory, where the near field coupling of the resonant geometries and ground is taken into account. Measurement results show good agreement with both the numerically simulated and theoretical results.

  5. A turn-on type stimuli-responsive fluorescent dye with specific solvent effect: Implication for a new prototype of paper using water as the ink

    Science.gov (United States)

    Hu, Xiaochen; Liu, Yang; Duan, Yuai; Han, Jingqi; Li, Zhongfeng; Han, Tianyu

    2017-09-01

    In this study, we reported the photoluminescence (PL) behaviour of a new intramolecular charge transfer (ICT) compound, ((E)-2-(((2-hydroxynaphthalen-1-yl)methylene)amino)benzoic acid, (HABA), which shows ICT solvent effect in aprotic solvents as confirmed by absorption and emission spectra. While in protic solvents including water and ethanol, the charge transfer (CT) band significantly reduces. Remarkable fluorescence enhancement in the blue region was also observed for HABA in polar protic solvents. We described such phenomena as ;specific solvent effect;. It can be ascribed to the hydrogen bonding formation between HABA and protic solvents, which not only causes significant reduction in the rate of internal conversion but also elevates the energy gap. Density functional theory (DFT) calculations as well as the dynamics analysis were performed to further verify the existence of hydrogen bonding complexes. Stronger emission turn-on effect was observed on HABA solid film when it is treated with water and base solution. The stimuli-responsive fluorescence of HABA enables a new green printing technique that uses water/base as the ink, affording fluorescent handwritings highly distinct from the background. Thermoanalysis of the dye suggests the nice thermostability, which is highly desired for real-world printing in a wide temperature range.

  6. Absorption and emission behaviour of trans- p-coumaric acid in aqueous solutions and some organic solvents

    Science.gov (United States)

    Putschögl, M.; Zirak, P.; Penzkofer, A.

    2008-01-01

    The absorption and fluorescence behaviour of trans- p-coumaric acid ( trans-4-hydroxycinnamic acid) is investigated in buffered aqueous solution over a wide range from pH 1 to pH 12, in un-buffered water, and in some organic solvents. Absorption cross-section spectra, fluorescence quantum distributions, fluorescence quantum yields, and degrees of fluorescence polarisation are measured. p-Coumaric acid exists in different ionic forms in aqueous solution depending on the pH. There is an equilibrium between the neutral form ( p-CAH 2) and the single anionic form ( p-CAH -) at low pH (p Kna ≈ 4.9), and between the single anionic and the double anionic form ( p-CA 2-) at high pH (p Kaa ≈ 9.35). In the organic solvents studied trans- p-coumaric acid is dissolved in its neutral form. The fluorescence quantum yield of trans- p-coumaric acid in aqueous solution is ϕF ≈ 1.4 × 10 -4 for the neutral and the single anionic form, while it is ϕF ≈ 1.3 × 10 -3 for the double anionic form. For trans- p-coumaric acid in organic solvents fluorescence quantum yields in the range from 4.8 × 10 -5 (acetonitrile) to 1.5 × 10 -4 (glycerol) were measured. The fluorescence spectra are 7700-10,000 cm -1 Stokes shifted in aqueous solution, and 5400-8200 cm -1 Stokes shifted in the studied organic solvents. Decay paths responsible for the low fluorescence quantum yields are discussed (photo-isomerisation and internal conversion for p-CA 2-, solvent-assisted intra-molecular charge-transfer or ππ ∗ to nπ ∗ transfer and internal conversion for p-CAH 2 and p-CAH -). The solvent dependence of the first ππ ∗ electronic transition frequency and of the fluorescence Stokes shift of p-CAH 2 is discussed in terms of polar solute-solvent interaction effects. Thereby the ground-state and excite-state molecular dipole moments are extracted.

  7. Absorption and emission behaviour of trans-p-coumaric acid in aqueous solutions and some organic solvents

    International Nuclear Information System (INIS)

    Putschoegl, M.; Zirak, P.; Penzkofer, A.

    2008-01-01

    The absorption and fluorescence behaviour of trans-p-coumaric acid (trans-4-hydroxycinnamic acid) is investigated in buffered aqueous solution over a wide range from pH 1 to pH 12, in un-buffered water, and in some organic solvents. Absorption cross-section spectra, fluorescence quantum distributions, fluorescence quantum yields, and degrees of fluorescence polarisation are measured. p-Coumaric acid exists in different ionic forms in aqueous solution depending on the pH. There is an equilibrium between the neutral form (p-CAH 2 ) and the single anionic form (p-CAH - ) at low pH (pK na ∼ 4.9), and between the single anionic and the double anionic form (p-CA 2- ) at high pH (pK aa ∼ 9.35). In the organic solvents studied trans-p-coumaric acid is dissolved in its neutral form. The fluorescence quantum yield of trans-p-coumaric acid in aqueous solution is φ F ∼ 1.4 x 10 -4 for the neutral and the single anionic form, while it is φ F ∼ 1.3 x 10 -3 for the double anionic form. For trans-p-coumaric acid in organic solvents fluorescence quantum yields in the range from 4.8 x 10 -5 (acetonitrile) to 1.5 x 10 -4 (glycerol) were measured. The fluorescence spectra are 7700-10,000 cm -1 Stokes shifted in aqueous solution, and 5400-8200 cm -1 Stokes shifted in the studied organic solvents. Decay paths responsible for the low fluorescence quantum yields are discussed (photo-isomerisation and internal conversion for p-CA 2- , solvent-assisted intra-molecular charge-transfer or ππ* to nπ* transfer and internal conversion for p-CAH 2 and p-CAH - ). The solvent dependence of the first ππ* electronic transition frequency and of the fluorescence Stokes shift of p-CAH 2 is discussed in terms of polar solute-solvent interaction effects. Thereby the ground-state and excite-state molecular dipole moments are extracted

  8. Visualization of polarization state and its application in optics classroom teaching

    Science.gov (United States)

    Lei, Bing; Liu, Wei; Shi, Jianhua; Wang, Wei; Yao, Tianfu; Liu, Shugang

    2017-08-01

    Polarization of light and the related knowledge are key and difficult points in optical teaching, and they are difficult to be understood since they are very abstract concepts. To help students understand the polarization properties of light, some classroom demonstration experiments have been constructed by employing the optical source, polarizers, wave plates optical cage system and polarization axis finder (PAF). The PAF is a polarization indicating device with many linear polarizing components concentric circles, which can visualize the polarization axis's direction of linearly polarized light intuitively. With the help of these demonstration experiment systems, the conversion and difference between the linear polarized light and circularly polarized light have been observed directly by inserting or removing a quarter-wave plate. The rotation phenomenon of linearly polarized light's polarization axis when it propagates through an optical active medium has been observed and studied in experiment, and the strain distribution of some mounted and unmounted lenses have also been demonstrated and observed in experiment conveniently. Furthermore, some typical polarization targets, such as liquid crystal display (LCD), polarized dark glass and skylight, have been observed based on PAF, which is quite suitable to help students understand these targets' polarization properties and the related physical laws. Finally, these demonstration experimental systems have been employed in classroom teaching of our university in physical optics, optoelectronics and photoelectric detection courses, and they are very popular with teachers and students.

  9. AKTIVITAS ANTIOKSIDAN DAN ANTIBAKTERI EKSTRAK POLAR DAN NON POLAR BIJI SELASIH (Ocimum sanctum Linn [Antioxidant and Antibacterial Activities from Polar and Non Polar Basil (Ocimum sanctum Linn Seed Extracts

    Directory of Open Access Journals (Sweden)

    Agustina D. R. Nurcahyanti1*

    2011-06-01

    Full Text Available The aims of this study were to determine total phenolic content, antioxidant activity and antibacterial activity of polar and nonpolar extracts of basil (O. sanctum L. seed. Seeds of basil (O. sanctum L. were extracted using a soxhlet extractor using four types organic solvent, i.e. chloroform, ethyl acetate, acetone, and methanol for eight hours each. The total phenolic content was determined using Folin Ciocalteu method, antioxidant activity was determined using reducing power and DPPH (1,1-diphenyl,2-picrylhydrazyl scavenging activity methods, while antibacterial activity was tested using agar diffusion method. The result showed that the highest total phenolic content and antioxidant activity was obtained in methanol extract with 3.63 ± 0.21 mgGAE/g phenolic total, 58.39 ± 3.81 ek/g using reducing power method and 85.73 ± 0.86% free radical scavenging activity. Furthermore the result of antibacterial activity testing showed that the highest diameter of inhibition zone was observed in ethyl acetate extract inhibition on E.coli, P.aeruginosa, B.subtilis, and S.aureus where its inhibition zone were 13.53 ± 0.63; 10.67 ± 1.05; 14.93 ± 0.80, and 13.46 ± 0.79 mm, respectively. This result suggests that both polar and nonpolar basil seed extracts possess specific biological activity. This data provide valuable and strong database for exploration of natural antibacterial agents and antioxidant for food and health industry application.

  10. Next Generation Solvent (NGS): Development for Caustic-Side Solvent Extraction of Cesium

    Energy Technology Data Exchange (ETDEWEB)

    Moyer, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Birdwell, Jr, Joseph F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bonnesen, Peter V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bruffey, Stephanie H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Delmau, Laetitia Helene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Duncan, Nathan C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ensor, Dale [Tennessee Technological Univ., Cookeville, TN (United States); Hill, Talon G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lee, Denise L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Rajbanshi, Arbin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Roach, Benjamin D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Szczygiel, Patricia L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sloop, Jr., Frederick V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Stoner, Erica L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Williams, Neil J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-03-01

    This report summarizes the FY 2010 and 2011 accomplishments at Oak Ridge National Laboratory (ORNL) in developing the Next Generation Caustic-Side Solvent Extraction (NG-CSSX) process, referred to commonly as the Next Generation Solvent (NGS), under funding from the U.S. Department of Energy, Office of Environmental Management (DOE-EM), Office of Technology Innovation and Development. The primary product of this effort is a process solvent and preliminary flowsheet capable of meeting a target decontamination factor (DF) of 40,000 for worst-case Savannah River Site (SRS) waste with a concentration factor of 15 or higher in the 18-stage equipment configuration of the SRS Modular Caustic-Side Solvent Extraction Unit (MCU). In addition, the NG-CSSX process may be readily adapted for use in the SRS Salt Waste Processing Facility (SWPF) or in supplemental tank-waste treatment at Hanford upon appropriate solvent or flowsheet modifications. Efforts in FY 2010 focused on developing a solvent composition and process flowsheet for MCU implementation. In FY 2011 accomplishments at ORNL involved a wide array of chemical-development activities and testing up through single-stage hydraulic and mass-transfer tests in 5-cm centrifugal contactors. Under subcontract from ORNL, Argonne National Laboratory (ANL) designed a preliminary flowsheet using ORNL cesium distribution data, and Tennessee Technological University confirmed a chemical model for cesium distribution ratios (DCs) as a function of feed composition. Interlaboratory efforts were coordinated with complementary engineering tests carried out (and reported separately) by personnel at Savannah River National Laboratory (SRNL) and Savannah River Remediation (SRR) with helpful advice by Parsons Engineering and General Atomics on aspects of possible SWPF implementation.

  11. Computer Aided Solvent Selection and Design Framework

    DEFF Research Database (Denmark)

    Mitrofanov, Igor; Conte, Elisa; Abildskov, Jens

    and computer-aided tools and methods for property prediction and computer-aided molecular design (CAMD) principles. This framework is applicable for solvent selection and design in product design as well as process design. The first module of the framework is dedicated to the solvent selection and design...... in terms of: physical and chemical properties (solvent-pure properties); Environment, Health and Safety (EHS) characteristic (solvent-EHS properties); operational properties (solvent–solute properties). 3. Performing the search. The search step consists of two stages. The first is a generation and property...... identification of solvent candidates using special software ProCAMD and ProPred, which are the implementations of computer-aided molecular techniques. The second consists of assigning the RS-indices following the reaction–solvent and then consulting the known solvent database and identifying the set of solvents...

  12. Improvements in solvent extraction columns

    International Nuclear Information System (INIS)

    Aughwane, K.R.

    1987-01-01

    Solvent extraction columns are used in the reprocessing of irradiated nuclear fuel. For an effective reprocessing operation a solvent extraction column is required which is capable of distributing the feed over most of the column. The patent describes improvements in solvent extractions columns which allows the feed to be distributed over an increased length of column than was previously possible. (U.K.)

  13. Outlier populations: individual and social network correlates of solvent-using injection drug users.

    Directory of Open Access Journals (Sweden)

    Souradet Y Shaw

    Full Text Available We previously identified a high prevalence of Hepatitis C (HCV amongst solvent-using injection drug users (S-IDU relative to other injection drug users within the same locality. Here we incorporated social network variables to better characterize some of the behavioural characteristics that may be putting this specific subgroup of IDU at elevated disease risk.A cross-sectional survey of at-risk populations was carried out in Winnipeg, Canada in 2009. Individuals reporting any history of injection drug and/or solvent use were included in the study. Associations between subgroup membership, infection with HCV and HIV and individual and social network variables were examined.In relation to other IDU, S-IDU were more likely to be infected with HCV, to report ever having shared a syringe, and to associate with other IDU. They were further differentiated in terms of their self-reported sexual orientation, ethnicity and in the injection drugs typically used.Solvent use stands as a proxy measure of numerous other characteristics that put this group of IDU at higher risk of infection. Provision of adequate services to ostracized subpopulations may result in wider population-level benefits.

  14. Creation of polarized ultracold neutrons and observation of Ramsey resonance for electric dipole moment measurement

    Energy Technology Data Exchange (ETDEWEB)

    Matsuta, K., E-mail: matsuta@vg.phys.sci.osaka-u.ac.jp [Osaka University, Department of Physics (Japan); Masuda, Y. [High Energy Accelerator Research Organization (KEK) (Japan); Hatanaka, K. [Osaka University, RCNP (Japan); Jeong, S. C.; Kawasaki, S. [High Energy Accelerator Research Organization (KEK) (Japan); Matsumiya, R. [Osaka University, RCNP (Japan); Mihara, M. [Osaka University, Department of Physics (Japan); Watanabe, Y. [High Energy Accelerator Research Organization (KEK) (Japan); Nishimura, D. [Tokyo University of Science, Department of Physics (Japan); Morita, Y. [Osaka University, Department of Physics (Japan); Asahi, K. [Tokyo Institute of Technology (Japan); Adachi, T. [High Energy Accelerator Research Organization (KEK) (Japan); Martin, J. [University of Winnipeg, Department of Physics (Canada); Konaka, A.; Miller, A. [TRIUMF (Canada); Bidinosti, C.; Dawson, T. [University of Winnipeg, Department of Physics (Canada); Lee, L.; Davis, C.; Ramsay, D. [TRIUMF (Canada); and others

    2013-05-15

    Polarized UCNs have been created by selecting only one spin state passing through a magnetized Fe foil. Typical degree of polarization was about 90 %. The polarization relaxation time in the prototype Ramsey cell was T{sub 1} =1100{sup +800}{sub -400} s. Clear Ramsey resonance spectra have been observed for two precession time settings, t{sub c} = 100 ms and 30 s. The transverse relaxation time T{sub 2} was about 50 s.

  15. Role of the reaction intermediates in determining PHIP (parahydrogen induced polarization) effect in the hydrogenation of acetylene dicarboxylic acid with the complex [Rh (dppb)]+ (dppb: 1,4-bis(diphenylphosphino)butane)

    International Nuclear Information System (INIS)

    Reineri, F.; Aime, S.; Gobetto, R.; Nervi, C.

    2014-01-01

    This study deals with the parahydrogenation of the symmetric substrate acetylene dicarboxylic acid catalyzed by a Rh(I) complex bearing the chelating diphosphine dppb (1,4-bis(diphenylphosphino)butane). The two magnetically equivalent protons of the product yield a hyperpolarized emission signal in the 1 H-NMR spectrum. Their polarization intensity varies upon changing the reaction solvent from methanol to acetone. A detailed analysis of the hydrogenation pathway is carried out by means of density functional theory calculations to assess the structure of hydrogenation intermediates and their stability in the two solvents. The observed polarization effects have been accounted on the basis of the obtained structures. Insights into the lifetime of a short-lived reaction intermediate are also obtained

  16. Dynamics of the quiet polar cap

    International Nuclear Information System (INIS)

    Carlson, H.C. Jr.

    1990-01-01

    Work in the past has established that a few percent of the time, under northward interplanetary magnetic field and thus magnetically quiet conditions, sun aligned arcs are found in the polar cap with intensities greater than the order of a kilo Rayleigh in the visible. Here we extend this view. We first note that imaging systems with sensitivity down to tens of Rayleighs in the visible find sun aligned arcs in the polar cap far more often, closer to half the time than a few percent. Furthermore, these sun aligned arcs have simple electrodynamics. They mark boundaries between rapid antisunward flow of ionospheric plasma on their dawn side and significantly slower flow, or even sunward flow, on their dusk side. Since the sun aligned arcs are typically the order of 1000 km to transpolar in the sun-earth direction, and the order of 100 km or less in the dawn-dusk direction, they demarcate lines of strongly anisotropic ionospheric flow shears or convection cells. The very quiet polar cap (strongly northward IMF) is in fact characterized by the presence of sun aligned arcs and multiple highly anisotropic ionospheric flow shears. Sensitive optical images are a valuable diagnostic with which to study polar ionospheric convection under these poorly understood conditions. (author)

  17. Processing of polymers using reactive solvents

    NARCIS (Netherlands)

    Lemstra, P.J.; Kurja, J.; Meijer, H.E.H.; Meijer, H.E.H.

    1997-01-01

    A review with many refs. on processing of polymers using reactive solvents including classification of synthetic polymers, guidelines for the selection of reactive solvents, basic aspects of processing, examples of intractable and tractable polymer/reactive solvent system

  18. Preparation of silver colloid and enhancement of dispersion stability in organic solvent

    International Nuclear Information System (INIS)

    Kim, Ki Young; Choi, Young Tai; Seo, Dae Jong; Park, Seung Bin

    2004-01-01

    Silver colloid of nanometer size was prepared in liquid phase by a reduction method. AgNO 3 , FeSO 4 .7H 2 O, and Na 3 C 6 H 5 O 7 .2H 2 O were used as silver precursor, reducing agent and dispersing agent, respectively. As precursor concentration was decreased or the concentration of dispersing agent was increased, the prepared particle size was decreased from 180 nm to 20 nm. Apparently, the particle size seemed to be decreased with the increase of stirring rate, but it was confirmed by TEM that the size of primary particle remained the same. This result indicates that the uniformity of precursor concentration in the reactor affects the particle size and the stirring rate should be kept higher than the critical value to prevent the agglomeration of particles. In order to make the dispersion stability of the prepared silver colloid maintained even in non-polar organic solvent, electrodialysis technique was applied. As ionic species in colloidal solution were removed by electrodialysis, the dispersability of the colloid in the organic solvent of long carbon chain was confirmed to be increased

  19. The effect of the electrode material on the electrodeposition of zinc from deep eutectic solvents

    International Nuclear Information System (INIS)

    Vieira, L.; Schennach, R.; Gollas, B.

    2016-01-01

    Highlights: • Mechanistic insight into zinc electrodeposition from deep eutectic solvents. • Overpotential for hydrogen evolution affects the electrodeposition of zinc. • Electrodeposited zinc forms surface alloys on Cu, Au, and Pt. • In situ PM-IRRAS of a ZnCl_2 containing deep eutectic solvent on glassy carbon. - Abstract: The voltammetric behaviour of the ZnCl_2 containing deep eutectic solvent choline chloride/ethylene glycol 1:2 was investigated on glassy carbon, stainless steel, Au, Pt, Cu, and Zn electrodes. While cyclic voltammetry on glassy carbon and stainless steel showed a cathodic peak for zinc electrodeposition only in the anodic reverse sweep, a cathodic peak was found also in the cathodic forward sweep on Au, Pt, Cu, and Zn. This behaviour is in agreement with the proposed mechanism of zinc deposition from an intermediate species Z, whose formation depends on the cathodic reduction potential of the solvent. The voltammetric reduction of the electrolyte involves hydrogen evolution and as a result the formation of Z and its reduction to zinc depend on the hydrogen overpotential for each electrode material. On Au, Pt, and Cu also the anodic stripping was different from that on glassy carbon and steel due to the formation of surface zinc alloys with the three former metals. The morphology of the zinc layers on Cu has been characterised by scanning electron microscopy and focussed ion beam. X-ray diffraction confirmed the presence of crystalline zinc and a Cu_4Zn phase. Spectroelectrochemistry by means of polarization modulation reflection-absorption spectroscopy (PM-IRRAS) on a glassy carbon electrode in the ZnCl_2 containing deep eutectic solvent showed characteristic potential dependent changes. The variation of band intensities at different applied potentials correlate with the voltammetry and suggest the formation of a compact blocking layer on the electrode surface, which inhibits the electrodeposition of zinc at sufficiently negative

  20. Polarization measurement for internal polarized gaseous targets

    International Nuclear Information System (INIS)

    Ye Zhenyu; Ye Yunxiu; Lv Haijiang; Mao Yajun

    2004-01-01

    The authors present an introduction to internal polarized gaseous targets, polarization method, polarization measurement method and procedure. To get the total nuclear polarization of hydrogen atoms (including the polarization of the recombined hydrogen molecules) in the target cell, authors have measured the parameters relating to atomic polarization and polarized hydrogen atoms and molecules. The total polarization of the target during our measurement is P T =0.853 ± 0.036. (authors)

  1. Effects of solvent and structure on the reactivity of 6-substituted nicotinic acids with diazodiphenylmethane in aprotic solvents

    Directory of Open Access Journals (Sweden)

    BRATISLAV Ž. JOVANOVIĆ

    2009-12-01

    Full Text Available The rate constants for the reactions of diazodiphenylmethane (DDM with 6-substituted nicotinic acids in aprotic solvents at 30 °C were determined. The obtained second order rate constants in aprotic solvents, together with literature data for benzoic and nicotinic acids in protic solvents, were used for the calculation of solvent effects, employing the Kamlet-Taft solvatochromic equation (linear solvation energy relationship – LSER in the form: log k = log k0 + s* + a + b. The correlations of the kinetic data were performed by means of multiple linear regression analysis taking appropriate solvent parameters. The sign of the equation coefficients (s, a and b were in agreement with the postulated reaction mechanism, and the mode of the solvent influences on the reaction rate is discussed based on the correlation results. A similar contribution of the non-specific solvent effect and electrophilic solvation was observed for all acids, while the highest contribution of nucleophilic solvation was influenced by their high acidity. Correlation analysis of the rate data with substituent p parameters in an appropriate solvent using the Hammett equation was also performed. The substituent effect on the acid reactivity was higher in aprotic solvents of higher dipolarity/polarizability. The mode of the transmission of the substituent effect is discussed in light of the contribution of solute–solvent interaction on the acid reactivity.

  2. Solubility of daidzin in different organic solvents and (ethyl alcohol + water) mixed solvents

    International Nuclear Information System (INIS)

    Fan, Jie-Ping; Yang, Dan; Xu, Xiao-Kang; Guo, Xiao-Jie; Zhang, Xue-Hong

    2015-01-01

    Highlights: • The solubilities of daidzin were measured in various solvents. • The solubility data were correlated by three models. • The thermodynamic properties of the dissolution process were also determined. - Abstract: The solubility of daidzin in different organic solvents and (ethyl alcohol + water) mixed solvents was measured by high performance liquid chromatography (HPLC) analysis method from T = (283.2 to 323.2) K at atmosphere pressure. The results show that at higher temperature more daidzin dissolves, and moreover, the solubility increases with the ethyl alcohol mole fraction increase in the (ethyl alcohol + water) mixed solvents. The experimental solubility values were correlated by a simplified thermodynamic equation, λh equation and modified Apelblat equation. Based on the solubility of daidzin, the enthalpy and entropy of solution were also evaluated by van’t Hoff equation. The results illustrated that the dissolution process of daidzin is endothermic and entropy driven

  3. Use of aqueous and solvent extraction to assess risk and bioavailability of contaminated soil

    International Nuclear Information System (INIS)

    Bordelon, N.; Huebner, H.; Washburn, K.; Donnelly, K.C.

    1995-01-01

    Contaminated media at Superfund sites typically consist of complex mixtures of organic and inorganic chemicals. These mixtures are difficult to characterize, both analytically and toxicologically, especially the complex mixtures of polycyclic aromatic hydrocarbons. The current approach to risk assessment assumes that all contaminants in the soil are available for human exposure. EPA protocol uses solvent extraction to remove chemicals from the soil as a basis for estimating risk to the human population. However, contaminants that can be recovered with a solvent extract may not represent chemicals that are available for exposure. A system using aqueous extraction provides a more realistic picture of what chemicals are bioavailable through leaching and ingestion. A study was conducted with coal tar contaminated soil spiked with benzo(a)pyrene, and trinitrotoluene. Samples were extracted with hexane:acetone and water titrated to pH 2 and pH 7. HPLC analysis demonstrated up to 35% and 29% recovery of contaminants from aqueous extracts with an estimated cancer risk one order of magnitude less than that for solvent extracts. Analysis using the Salmonella/microsome assay showed that solvent extracts were genotoxic with metabolic activation while aqueous extracts showed no genotoxicity. These results suggest that aqueous extraction may be useful in determining what contaminants are available for human exposure, as well as what compounds may pose a risk to human health

  4. One-pot synthesis of stable colloidal solutions of MFe2O4 nanoparticles using oleylamine as solvent and stabilizer

    International Nuclear Information System (INIS)

    Pérez-Mirabet, Leonardo; Solano, Eduardo; Martínez-Julián, Fernando; Guzmán, Roger; Arbiol, Jordi; Puig, Teresa; Obradors, Xavier; Pomar, Alberto; Yáñez, Ramón; Ros, Josep; Ricart, Susagna

    2013-01-01

    Highlights: ► One-pot synthesis of ferrite magnetic nanoparticles ( 3 and M(acac) 2 (M = Co, Mn, Cu and Zn) in oleylamine, which also acts as a capping ligand, by producing stable colloidal dispersions of nanoparticles in non-polar solvents. The properties of the nanoparticles have been studied via different techniques, such as transmission electron microscopy, which shows that nanoparticles are monocrystallines and a narrow dispersion in size; magnetic analyses have demonstrated that the resulting ferrite nanoparticles show high saturation values and superparamagnetic behavior at room temperature; X-ray diffraction has also been performed, and it confirms that the synthesized nanoparticles have a spinel structure. Complementarily, ligand exchange has been also carried out in order to produce dispersions of the synthesized nanoparticles in polar media

  5. Environmental analysis of the life cycle emissions of 2-methyl tetrahydrofuran solvent manufactured from renewable resources.

    Science.gov (United States)

    Slater, C Stewart; Savelski, Mariano J; Hitchcock, David; Cavanagh, Eduardo J

    2016-01-01

    An environmental analysis has been conducted to determine the cradle to gate life cycle emissions to manufacture the green solvent, 2-methyl tetrahydrofuran. The solvent is considered a greener chemical since it can be manufactured from renewable resources with a lower life cycle footprint. Analyses have been performed using different methods to show greenness in both its production and industrial use. This solvent can potentially be substituted for other ether and chlorinated solvents commonly used in organometallic and biphasic reactions steps in pharmaceutical and fine chemical syntheses. The 2-methyl tetrahydrofuran made from renewable agricultural by-products is marketed by Penn A Kem under the name ecoMeTHF™. The starting material, 2-furfuraldehyde (furfural), is produced from corn cob waste by converting the available pentosans by acid hydrolysis. An evaluation of each step in the process was necessary to determine the overall life cycle and specific CO2 emissions for each raw material/intermediate produced. Allocation of credits for CO2 from the incineration of solvents made from renewable feedstocks significantly reduced the overall carbon footprint. Using this approach, the overall life cycle emissions for production of 1 kg of ecoMeTHF™ were determined to be 0.191 kg, including 0.150 kg of CO2. Life cycle emissions generated from raw material manufacture represents the majority of the overall environmental impact. Our evaluation shows that using 2-methyl tetrahydrofuran in an industrial scenario results in a 97% reduction in emissions, when compared to typically used solvents such as tetrahydrofuran, made through a conventional chemical route.

  6. Status and future plans of polarized beams at COSY

    Science.gov (United States)

    Lorentz, B.; Gebel, R.; Lehrach, A.; Maier, R.; Prasuhn, D.; Stockhorst, H.

    2011-05-01

    In this paper we report on the present status and future plans of polarized beams in the COSY synchrotron ring. COSY is a synchrotron ring in the momentum range from 295 to 3700 MeV/c. Polarized deuterons and protons are routinely delivered to experiments over the whole momentum range. No depolarization occurs during the acceleration of deuterons in COSY. For polarized protons many depolarizing resonances are crossed without polarization loss. At imperfection resonances, vertical steerer magnets are used to increase the resonance strength, leading to a complete polarization reversal. At intrinsic resonances a fast tune jump quadrupole is used to quickly cross the resonances without loss of polarization. Typical proton polarizations are close to 0.8 below 2.1 GeV/c and about 0.6 for higher momenta. During recent operation an induced depolarizing resonance was used for accurate determination of the relative momentum spread dp/p of the stored beam yielding an accuracy of better than 10-4. For spin filter studies of the PAX collaboration a low beta target section was installed in 2009 and was successfully put into operation early 2010. An upgrade of the EDDA polarimeter electronics and data acquisition system is underway to ensure continued availability of the polarimeter, which is essential for the polarized proton operation of COSY. In the near future it is planned to install a Siberian snake solenoid of 4.5 Tm to be able to provide in addition to vertically polarized protons, longitudinal polarization as well. This solenoid will allow the preparation of a longitudinally polarized beam up to a kinetic energy of 500 MeV.

  7. Fast, high-fidelity, all-optical and dynamically-controlled polarization gate using room-temperature atomic vapor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Runbing [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Center for Cold Atom Physics, Chinese Academy of Sciences, Wuhan 430071 (China); Zhu, Chengjie [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Deng, L.; Hagley, E. W. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

    2014-10-20

    We demonstrate a fast, all-optical polarization gate in a room-temperature atomic medium. Using a Polarization-Selective-Kerr-Phase-Shift (PSKPS) technique, we selectively write a π phase shift to one circularly-polarized component of a linearly-polarized input signal field. The output signal field maintains its original strength but acquires a 90° linear polarization rotation, demonstrating fast, high-fidelity, dynamically-controlled polarization gate operation. The intensity of the polarization-switching field used in this PKSPK-based polarization gate operation is only 2 mW/cm{sup 2}, which would be equivalent to 0.5 nW of light power (λ = 800 nm) confined in a typical commercial photonic hollow-core fiber. This development opens a realm of possibilities for potential future extremely low light level telecommunication and information processing systems.

  8. Adaptive Resolution Simulation of MARTINI Solvents

    NARCIS (Netherlands)

    Zavadlav, Julija; Melo, Manuel N.; Cunha, Ana V.; de Vries, Alex H.; Marrink, Siewert J.; Praprotnik, Matej

    We present adaptive resolution dynamics simulations of aqueous and apolar solvents coarse-grained molecular models that are compatible with the MARTINI force field. As representatives of both classes solvents we have chosen liquid water and butane, respectively, at ambient temperature. The solvent

  9. Green and Bio-Based Solvents.

    Science.gov (United States)

    Calvo-Flores, Francisco G; Monteagudo-Arrebola, María José; Dobado, José A; Isac-García, Joaquín

    2018-04-24

    Chemical reactions and many of the procedures of separation and purification employed in industry, research or chemistry teaching utilize solvents massively. In the last decades, with the birth of Green Chemistry, concerns about the employment of solvents and the effects on human health, as well as its environmental impacts and its dependence on non-renewable raw materials for manufacturing most of them, has drawn the attention of the scientific community. In this work, we review the concept of green solvent and the properties and characteristics to be considered green. Additionally, we discuss the different possible routes to prepare many solvents from biomass, as an alternative way to those methods currently applied in the petrochemical industry.

  10. Production of highly polarized 3He using spectrally narrowed diode laser array bars

    International Nuclear Information System (INIS)

    Chann, B.; Babcock, E.; Anderson, L.W.; Walker, T.G.; Chen, W.C.; Smith, T.B.; Thompson, A.K.; Gentile, T.R.

    2003-01-01

    We have produced 70%-75% 3 He polarization by spin-exchange optical pumping in cells ≅100 cm 3 in volume. The polarization achieved is consistent with known spin-exchange and spin-relaxation rates, but only when the recently discovered temperature dependence of 3 He relaxation is included. Absolute 3 He polarization measurements were performed using two different methods in two different laboratories. The results were obtained with either a spectrally narrowed laser or one type of broadband laser. Based on tests of several larger cells at pressures near 1 bar, we find that the power required to reach the same polarization is typically three times lower for the spectrally narrowed laser. This last result indicates that spectrally narrowed lasers will be important for obtaining the highest polarization in large volume neutron spin filters. Polarization in excess of 55% as obtained in cells up to 640 cm 3 in volume and 70% polarization is anticipated with available increases in spectrally narrowed laser power

  11. Active Polar Two-Fluid Macroscopic Dynamics

    Science.gov (United States)

    Pleiner, Harald; Svensek, Daniel; Brand, Helmut R.

    2014-03-01

    We study the dynamics of systems with a polar dynamic preferred direction. Examples include the pattern-forming growth of bacteria (in a solvent, shoals of fish (moving in water currents), flocks of birds and migrating insects (flying in windy air). Because the preferred direction only exists dynamically, but not statically, the macroscopic variable of choice is the macroscopic velocity associated with the motion of the active units. We derive the macroscopic equations for such a system and discuss novel static, reversible and irreversible cross-couplings connected to this second velocity. We find a normal mode structure quite different compared to the static descriptions, as well as linear couplings between (active) flow and e.g. densities and concentrations due to the genuine two-fluid transport derivatives. On the other hand, we get, quite similar to the static case, a direct linear relation between the stress tensor and the structure tensor. This prominent ``active'' term is responsible for many active effects, meaning that our approach can describe those effects as well. In addition, we also deal with explicitly chiral systems, which are important for many active systems. In particular, we find an active flow-induced heat current specific for the dynamic chiral polar order.

  12. Effect of synthesis solvent on the breathing behavior of MIL-53(Al).

    Science.gov (United States)

    Mounfield, William P; Walton, Krista S

    2015-06-01

    This work reports the effect of using dimethylformamide (DMF) as the solvent for synthesizing MIL-53(Al). This well-known breathing MOF is typically prepared using hydrothermal methods. The two materials synthesized in DMF at 120°C and 220°C show significant deviations from the breathing behavior exhibited by the material synthesized hydrothermally. Powder X-ray diffraction confirmed that MIL-53(Al) synthesized in DMF at 120°C remains in the large-pore form under all conditions, while the other material synthesized at 220°C undergoes a more gradual breathing transition than is observed for MIL-53(Al) prepared by traditional methods. Solid-state NMR was employed to elucidate additional structural information and gain insight into the role synthesis solvent plays on breathing behavior. The CO2 and water adsorption of these large-pore stabilized materials were studied, and the differences in adsorption behavior compared to MIL-53(Al) prepared by traditional methods was discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Enthalpies of solvation of ethylene oxide oligomers CH{sub 3}O(CH{sub 2}CH{sub 2}O){sub n}CH{sub 3} (n = 1 to 4) in different H-bonding solvents: Methanol, chloroform, and water. Group contribution method as applied to the polar oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Barannikov, Vladimir P., E-mail: vpb@isc-ras.ru [Institute of Solution Chemistry, Russian Academy of Sciences, Academicheskaya Str. 1, Ivanovo 153045 (Russian Federation); Guseynov, Sabir S.; Vyugin, Anatoliy I. [Institute of Solution Chemistry, Russian Academy of Sciences, Academicheskaya Str. 1, Ivanovo 153045 (Russian Federation)

    2011-12-15

    Highlights: > Solvation enthalpy is found for ethylene oxide oligomers in chloroform and methanol. > Coefficients of solute-solute interaction are determined for oligomers in methanol. > Enthalpies of hydrogen bonding of oligomers with chloroform and water are estimated. > Additivity scheme is developed for describing enthalpies of solvation of oligomers. - Abstract: The enthalpies of solution and solvation of ethylene oxide oligomers CH{sub 3}O(CH{sub 2}CH{sub 2}O){sub n}CH{sub 3} (n = 1 to 4) in methanol and chloroform have been determined from calorimetric measurements at T = 298.15 K. The enthalpic coefficients of pairwise solute-solute interaction for methanol solutions have been calculated. The enthalpic characteristics of the oligomers in methanol, chloroform, water and tetrachloromethane have been compared. The hydrogen bonding of the oligomers with chloroform and water molecules is exhibited in the values of solvation enthalpy and coefficient of solute-solute interaction. This effect is not observed for methanol solvent. The thermochemical data evidence an existence of multi-centred hydrogen bonds in associates of polyethers with the solvent molecules. Enthalpies of hydrogen bonding of the oligomers with chloroform and water have been estimated. The additivity scheme has been developed to describe the enthalpies of solvation of ethylene oxide oligomers, unbranched monoethers and n-alkanes in chloroform, methanol, water, and tetrachloromethane. The correction parameters for contribution of repeated polar groups and correction term for methoxy-compounds have been introduced. The obtained group contributions permit to describe the enthalpies of solvation of unbranched monoethers and ethylene oxide oligomers in the solvents with standard deviation up to 0.6 kJ . mol{sup -1}. The values of group contributions and corrections are strongly influenced by solvent properties.

  14. Miscibility Evaluation Of The Next Generation Solvent With Polymers Currently Used At DWPF, MCU, And Saltstone

    Energy Technology Data Exchange (ETDEWEB)

    Fondeur, F. F.

    2013-04-17

    The Office of Waste Processing, within the Office of Technology Innovation and Development, funded the development of an enhanced Caustic-Side Solvent Extraction (CSSX) solvent for deployment at the Savannah River Site for removal of cesium from High Level Waste. This effort lead to the development of the Next Generation Solvent (NGS) with Tris (3,7-dimethyl octyl) guanidine (TiDG). The first deployment target for the NGS solvent is within the Modular CSSX Unit (MCU). Deployment of a new chemical within an existing facility requires verification that the new chemical components are compatible with the installed equipment. In the instance of a new organic solvent, the primary focus is on compatibility of the solvent with organic polymers used in the affected facility. This report provides the calculated data from exposing these polymers to the Next Generation Solvent. An assessment of the dimensional stability of polymers known to be used or present in the MCU, Defense Waste Processing Facility (DWPF), and Saltstone facilities that will be exposed to the NGS showed that TiDG could selectively affect the elastomers and some thermoplastics to varying extents, but the typical use of these polymers in a confined geometry will likely prevent the NGS from impacting component performance. The polymers identified as of primary concern include Grafoil® (flexible graphite), Tefzel®, Isolast®, ethylene-propylene-diene monomer (EPDM) rubber, nitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), ultra high molecular weight polyethylene (UHMWPE), and fluorocarbon rubber (FKM). Certain polymers like NBR and EPDM were found to interact mildly with NGS but their calculated swelling and the confined geometry will impede interaction with NGS. In addition, it was found that Vellumoid (cellulose fibers-reinforced glycerin and protein) may leach protein and Polyvinyl Chloride (PVC) may leach plasticizer (such as Bis-Ethylhexyl-Phthalates) into the NGS solvent. Either case

  15. Solvent Extraction of Furfural From Biomass

    Science.gov (United States)

    Humphrey, M. F.

    1984-01-01

    Solvent-extraction method reduces energy required to remove furfural produced during acid hydrolysis of biomass. Acid hydrolysis performed in vessel containing both solvents and reacting ingredients. With intimate contact between solvents and aqueous hydrolyis liqour, furfural removed form liquor almost as fast as it forms.

  16. Flavor release and perception in hard candy: influence of flavor compound-flavor solvent interactions.

    Science.gov (United States)

    Schober, Amanda L; Peterson, Devin G

    2004-05-05

    The release kinetics of l-menthol dissolved in propylene glycol (PG), Miglyol, or 1,8-cineole (two common odorless flavor solvents differing in polarity and a hydrophobic flavor compound) were monitored from a model aqueous system via atmospheric pressure chemical ionization mass spectrometry (APCI-MS). Breath analysis was also conducted via APCI-MS to monitor release of l-menthol from hard candy that used PG and Miglyol for l-menthol incorporation. The quantities of l-menthol released when dissolved in PG or Miglyol from the model aqueous system were found to be similar and overall significantly greater in comparison to when dissolved in 1,8-cineole. Analogous results were reported by the breath analysis of hard candy. The release kinetics of l-menthol from PG or Miglyol versus from 1,8-cineole were notably more rapid and higher in quantity. Results from the sensory time-intensity study also indicated that there was no perceived difference in the overall cooling intensity between the two flavor solvent delivery systems (PG and Miglyol).

  17. Homogeneous solutions of hydrophilic enzymes in nonpolar organic solvents. New systems for fundamental studies and biocatalytic transformations.

    Science.gov (United States)

    Mozhaev, V V; Poltevsky, K G; Slepnev, V I; Badun, G A; Levashov, A V

    1991-11-04

    A typical hydrophilic enzyme, CT, can be dissolved in nonpolar organic solvents (n-octane, cyclohexane and toluene) up to microM concentrations. In the homogeneous solution obtained, the enzyme possesses catalytic activity and enormously high thermostability. It does not lose this activity even after several hours refluxing in octane (126 degrees C) or cyclohexane (81 degrees C).

  18. Biodiesel production from ethanolysis of palm oil using deep eutectic solvent (DES) as co-solvent

    Science.gov (United States)

    Manurung, R.; Winarta, A.; Taslim; Indra, L.

    2017-06-01

    Biodiesel produced from ethanolysis is more renewable and have better properties (higher oxidation stability, lower cloud and pour point) compared to methanolysis, but it has a disadvantage such as complicated purification. To improve ethanolysis process, deep eutectic solvent (DES) can be prepared from choline chloride and glycerol and used as co-solvent in ethanolysis. The deep eutectic solvent is formed from a quaternary ammonium salt (choline chloride) and a hydrogen bond donor (Glycerol), it is a non-toxic, biodegradable solvent compared to a conventional volatile organic solvent such as hexane. The deep eutectic solvent is prepared by mixing choline chloride and glycerol with molar ratio 1:2 at temperature 80 °C, stirring speed 300 rpm for 1 hour. The DES is characterized by its density and viscosity. The ethanolysis is performed at a reaction temperature of 70 °C, ethanol to oil molar ratio of 9:1, potassium hydroxide as catalyst concentration of 1.2 wt. DES as co-solvent with concentration 0.5 to 3 wt. stirring speed 400 rpm, and a reaction time 1 hour. The obtained biodiesel is then characterized by its density, viscosity, and ester content. The oil - ethanol phase condition is observed in the reaction tube. The oil - ethanol phase with DES tends to form meniscus compared to without DES, showed that oil and ethanol become more slightly miscible, which favors the reaction. Using DES as co-solvent in ethanolysis showed increasing in yield and easier purification. The esters properties meet the international standards ASTM D6751, with the highest yield achieved 83,67 with 99,77 conversion at DES concentration 2 . Increasing DES concentration above 2 in ethanolysis decrease the conversion and yield, because of the excessive glycerol in the systems makes the reaction equilibrium moves to the reactant side.

  19. Alfvénic fluctuations in "newborn"' polar solar wind

    Directory of Open Access Journals (Sweden)

    B. Bavassano

    2005-06-01

    Full Text Available The 3-D structure of the solar wind is strongly dependent upon the Sun's activity cycle. At low solar activity a bimodal structure is dominant, with a fast and uniform flow at the high latitudes, and slow and variable flows at low latitudes. Around solar maximum, in sharp contrast, variable flows are observed at all latitudes. This last kind of pattern, however, is a relatively short-lived feature, and quite soon after solar maximum the polar wind tends to regain its role. The plasma parameter distributions for these newborn polar flows appear very similar to those typically observed in polar wind at low solar activity. The point addressed here is about polar wind fluctuations. As is well known, the low-solar-activity polar wind is characterized by a strong flow of Alfvénic fluctuations. Does this hold for the new polar flows too? An answer to this question is given here through a comparative statistical analysis on parameters such as total energy, cross helicity, and residual energy, that are of general use to describe the Alfvénic character of fluctuations. Our results indicate that the main features of the Alfvénic fluctuations observed in low-solar-activity polar wind have been quickly recovered in the new polar flows developed shortly after solar maximum. Keywords. Interplanetary physics (MHD waves and turbulence; Sources of the solar wind – Space plasma physics (Turbulence

  20. Organic Solvent Tolerant Lipases and Applications

    Directory of Open Access Journals (Sweden)

    Shivika Sharma

    2014-01-01

    Full Text Available Lipases are a group of enzymes naturally endowed with the property of performing reactions in aqueous as well as organic solvents. The esterification reactions using lipase(s could be performed in water-restricted organic media as organic solvent(s not only improve(s the solubility of substrate and reactant in reaction mixture but also permit(s the reaction in the reverse direction, and often it is easy to recover the product in organic phase in two-phase equilibrium systems. The use of organic solvent tolerant lipase in organic media has exhibited many advantages: increased activity and stability, regiospecificity and stereoselectivity, higher solubility of substrate, ease of products recovery, and ability to shift the reaction equilibrium toward synthetic direction. Therefore the search for organic solvent tolerant enzymes has been an extensive area of research. A variety of fatty acid esters are now being produced commercially using immobilized lipase in nonaqueous solvents. This review describes the organic tolerance and industrial application of lipases. The main emphasis is to study the nature of organic solvent tolerant lipases. Also, the potential industrial applications that make lipases the biocatalysts of choice for the present and future have been presented.

  1. Interrogation and mitigation of polarization effects for standard and birefringent FBGs

    Science.gov (United States)

    Ibrahim, Selwan K.; Van Roosbroeck, Jan; O'Dowd, John A.; Van Hoe, Bram; Lindner, Eric; Vlekken, Johan; Farnan, Martin; Karabacak, Devrez M.; Singer, Johannes M.

    2016-05-01

    Optical sensors based on Fiber Bragg Gratings (FBGs) are used in several applications and industries. Several inscription techniques and type of fibers can be used. However, depending on the writing process, type of fiber used and the packaging of the sensor a Polarization Dependent Frequency Shift (PDFS) can often be observed with polarized tunable laser based optical interrogators. Here we study the PDFS of the FBG peak for the different FBG types. A PDFS of 20pm was observed across the FBGs. To mitigate and reduce this effect we propose a polarization mitigation technique which relies on a synchronous polarization switch to reduce the effect typically by a factor greater than 4. In other scenarios the sensor itself is designed to be birefringent (Bi-FBG) to allow pressure and/or simultaneous temperature and strain measurements. Using the same polarization switch we demonstrate how we can interrogate the Bi-FBGs with high accuracy to enable high performance of such sensors to be achievable.

  2. Abiotic systems for the catalytic treatment of solvent-contaminated water

    Energy Technology Data Exchange (ETDEWEB)

    Betterton, E.A.; Arnold, R.G.; Liu, Zhijie; Hollan, N. [Univ. of Arizona, Tucson, AZ (United States)] [and others

    1996-12-31

    Three abiotic systems are described that catalyze the reductive dehalogenation of heavily halogenated environmental pollutants, including carbon tetrachloride, trichloroethene, and perchloroethene. These systems include (a) an electrolytic reactor in which the potential on the working electrode (cathode) is fixed by using a potentiostat, (b) a light-driven system consisting of a semiconductor and (covalently attached) macrocycle that can accept light transmitted via an optical fiber, and a light-driven, two-solvent (isopropanol/acetone) system that promotes dehalogenation reactions via an unknown mechanism. Each is capable of accelerating reductive dehalogenation reactions to very high rates under laboratory conditions. Typically, millimolar concentrations of aqueous-phase targets can be dehalogenated in minutes to hours. The description of each system includes the elements of reaction mechanism (to the extent known), typical kinetic data, and a discussion of the feasibility of applying this technology for the in situ destruction of hazardous compounds. 14 refs., 11 figs., 2 tabs.

  3. Computer-aided tool for solvent selection in pharmaceutical processes: Solvent swap

    DEFF Research Database (Denmark)

    Papadakis, Emmanouil; K. Tula, Anjan; Gernaey, Krist V.

    -liquid equilibria). The application of the developed model-based framework is highlighted through several cases studies published in the literature. In the current state, the framework is suitable for problems where the original solvent is exchanged by distillation. A solvent selection guide for fast of suitable......-aided framework with the objective to assist the pharmaceutical industry in gaining better process understanding. A software interface to improve the usability of the tool has been created also....

  4. Effects of solvent evaporation conditions on solvent vapor annealed cylinder-forming block polymer thin films

    Science.gov (United States)

    Grant, Meagan; Jakubowski, William; Nelson, Gunnar; Drapes, Chloe; Baruth, A.

    Solvent vapor annealing is a less time and energy intensive method compared to thermal annealing, to direct the self-assembly of block polymer thin films. Periodic nanostructures have applications in ultrafiltration, magnetic arrays, or other structures with nanometer dimensions, driving its continued interest. Our goal is to create thin films with hexagonally packed, perpendicular aligned cylinders of poly(lactide) in a poly(styrene) matrix that span the thickness of the film with low anneal times and low defect densities, all with high reproducibility, where the latter is paramount. Through the use of our computer-controlled, pneumatically-actuated, purpose-built solvent vapor annealing chamber, we have the ability to monitor and control vapor pressure, solvent concentration within the film, and solvent evaporation rate with unprecedented precision and reliability. Focusing on evaporation, we report on two previously unexplored areas, chamber pressure during solvent evaporation and the flow rate of purging gas aiding the evaporation. We will report our exhaustive results following atomic force microscopy analysis of films exposed to a wide range of pressures and flow rates. Reliably achieving well-ordered films, while occurring within a large section of this parameter space, was correlated with high-flow evaporation rates and low chamber pressures. These results have significant implications on other methods of solvent annealing, including ``jar'' techniques.

  5. World polarization in carbon emissions, potential conflict and groups: An updated revision

    International Nuclear Information System (INIS)

    Antonio Duro, Juan; Teixidó-Figueras, Jordi

    2014-01-01

    Typically, conflicts in world environmental negotiations are related, amongst other aspects, to the level of polarization of the countries in groups with conflicting interests. Given the predictable relationship between polarization and conflict, it would seem logical to evaluate the degree to which the distribution of countries – for example, in terms of their CO 2 emissions per capita – would be structured through groups which in themselves are antagonistic, as well as their evolution over time. This paper takes the concept of polarization to explore this distribution for the period 1992–2010, looking at different analytic approaches related to the concept. Specifically, it makes a comparative evaluation of the results associated with endogenous multi-polarization measures (i.e. EGR and DER indices), exogenous measures (i.e. Z–K or multidimensional index) and strict bipolarization measures (i.e. Wolfson’s measure). Indeed, the interest lies not only in evaluating the global situation of polarization by comparing the different approaches and their temporal patterns, but also in examining the explanatory capacity of the different proxy groups used as a possible reference for designing global environmental policy from a group premise. - Highlights: • The world seems to have (multi) polarized typically less in terms of carbon emissions since 1992. • The advance of the within-groups cohesion and the equalization in their size allows some caution. • The division of countries into two endogenous groups appears as relevant. • It would be interesting the simplification through three exogenous income-groups of countries. • It would seem useful to design global negotiating mechanisms based on these types of groups

  6. On linear correlation between interfacial tension of water-solvent interface solubility of water in organic solvents and parameters of diluent effect scale

    International Nuclear Information System (INIS)

    Mezhov, Eh.A.; Khananashvili, N.L.; Shmidt, V.S.

    1988-01-01

    Presence of linear correlation between water solubility in nonmiscible with it organic solvents, interfacial tension of water-solvent interface, on the one hand, and solvent effect scale parameters and these solvents π* - on the other hand, is established. It allows, using certain tabular parameters of solvent effect or each solvent π*, to predict values of interfacial tension and water solubility for corresponding systems. It is shown, that solvent effect scale allows to predict values more accurately, than other known solvent scales, as it in contrast to other scales characterizes solvents, which are in equilibrium with water

  7. Principle for the Realization of Dual-Orthogonal Linearly Polarized Antennas for UWB Technique

    Directory of Open Access Journals (Sweden)

    Grzegorz Adamiuk

    2011-01-01

    The presented method introduces a superior possibility of an extension of typical UWB technique to fully polarized systems, which improves significantly performance in, for example, UWB-MIMO or UWB-Radar.

  8. Linear correlation of interfacial tension at water-solvent interface, solubility of water in organic solvents, and SE* scale parameters

    International Nuclear Information System (INIS)

    Mezhov, E.A.; Khananashvili, N.L.; Shmidt, V.S.

    1988-01-01

    A linear correlation has been established between the solubility of water in water-immiscible organic solvents and the interfacial tension at the water-solvent interface on the one hand and the parameters of the SE* and π* scales for these solvents on the other hand. This allows us, using the known tabulated SE* or π* parameters for each solvent, to predict the values of the interfacial tension and the solubility of water for the corresponding systems. We have shown that the SE* scale allows us to predict these values more accurately than other known solvent scales, since in contrast to other scales it characterizes solvents found in equilibrium with water

  9. Internal electric fields of electrolytic solutions induced by space-charge polarization

    Science.gov (United States)

    Sawada, Atsushi

    2006-10-01

    The dielectric dispersion of electrolytic solutions prepared using chlorobenzene as a solvent and tetrabutylammonium tetraphenylborate as a solute is analyzed in terms of space-charge polarization in order to derive the ionic constants, and the Stokes radius obtained is discussed in comparison with the values that have been measured by conductometry. A homogeneous internal electric field is assumed for simplicity in the analysis of the space-charge polarization. The justification of the approximation by the homogeneous field is discussed from two points of view: one is the accuracy of the Stokes radius value observed and the other is the effect of bound charges on electrodes in which they level the highly inhomogeneous field, which has been believed in the past. In order to investigate the actual electric field, numerical calculations based on the Poisson equation are carried out by considering the influence of the bound charges. The variation of the number of bound charges with time is clarified by determining the relaxation function of the dielectric constant attributed to the space-charge polarization. Finally, a technique based on a two-field approximation, where homogeneous and hyperbolic fields are independently applied in relevant frequency ranges, is introduced to analyze the space-charge polarization of the electrolytic solutions, and further improvement of the accuracy in the determination of the Stokes radius is achieved.

  10. 29 CFR 1915.32 - Toxic cleaning solvents.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Toxic cleaning solvents. 1915.32 Section 1915.32 Labor... Preservation § 1915.32 Toxic cleaning solvents. (a) When toxic solvents are used, the employer shall employ one or more of the following measures to safeguard the health of employees exposed to these solvents. (1...

  11. Simultaneous observations of sun-aligned polar cap arcs in both hemispheres by EXOS-C and viking

    International Nuclear Information System (INIS)

    Obara, T.; Kitayama, M.; Mukai, T.; Kaya, N.; Murphree, J.S.; Cogger, L.L.

    1988-01-01

    On September 25, 1986, the EXOS-C satellite traversed an intense electron precipitation in the southern polar cap, while the Viking satellite simultaneously obtained image data of the polar cap arc in the northern hemisphere. The energy spectrum of the precipitation, measured by instrumentation aboard EXOS-C, was very similar to that of adjacent (typical) auroral arcs, and the precipitation in the southern polar cap was observed in the same local time sector in which the arc was found in the northern polar cap. Observations seem to support the view that the polar cap arc occurs on closed field lines and is conjugate in both hemispheres. copyright American Geophysical Union 1988

  12. Analysis of recovered solvents from coal liquefaction in a flowing-solvent reactor by SEC and UV-fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Li, W.Y.; Feng, J.; Xie, K.C.; Kandiyoti, R. [Taiyuan University of Technology, Taiyuan (China)

    2005-08-01

    Point of Ayr coal has been extracted using three solvents: tetralin, quinoline and 1-methyl-2-pyrrolidinone (NMP); at two temperatures: 350 {sup o}C and 450{sup o}C, corresponding approximately to before and after the onset of massive covalent bond scission by pyrolysis. These solvents differ in solvent power and the ability to donate hydrogen atoms to stabilize free radicals produced by pyrolysis of the coal. Analysis of the fresh solvents and recovered solvents from coal liquefaction was achieved by size exclusion chromatography and UV-fluorescence spectroscopy. In the blank run, it was testified that the filling material sand and the steel powder did not react with solvent with increasing reaction temperature. The role of hydrogen donation in the tetralin extracts was to increase the proportion of large molecules with increasing extraction temperature. Quinoline and NMP both have the powerful extracting capability to get more materials out of coal with increasing extraction temperature.

  13. Analysis of recovered solvents from coal liquefaction in a flowing-solvent reactor by SEC and UV-fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Wen-Ying Li; Jie Feng; Ke-Chang Xie; R. Kandiyoti [Taiyuan University of Technology, Taiyuan (China). Key Laboratory of Coal Science and Technology for Ministry of Education and Shanxi Province

    2005-08-01

    Point of Ayr coal has been extracted using three solvents: tetralin, quinoline and 1-methyl-2-pyrrolidinone (NMP); at two temperatures: 350{sup o}C and 450{sup o}C, corresponding approximately to before and after the onset of massive covalent bond scission by pyrolysis. These solvents differ in solvent power and the ability to donate hydrogen atoms to stabilize free radicals produced by pyrolysis of the coal. Analysis of the fresh solvents and recovered solvents from coal liquefaction was achieved by size exclusion chromatography and UV-fluorescence spectroscopy. In the blank run, it was testified that the filling material sand and the steel powder did not react with solvent with increasing reaction temperature. The role of hydrogen donation in the tetralin extracts was to increase the proportion of large molecules with increasing extraction temperature. Quinoline and NMP both have the powerful extracting capability to get more materials out of coal with increasing extraction temperature.

  14. Evidences for decarbonation and exfoliation of layered double hydroxide in N,N-dimethylformamide-ethanol solvent mixture

    International Nuclear Information System (INIS)

    Gordijo, Claudia R.; Leopoldo Constantino, Vera R.; Oliveira Silva, Denise de

    2007-01-01

    The behavior of a Hydrotalcite-like material (carbonate-containing Mg,Al-layered double hydroxide) in N,N-dimethylformamide (DMF)-ethanol mixture, at ambient temperature, has been investigated. The releasing of CO 2 and production of a formate-containing material occurred mainly for 1:1 (v/v) solvent mixture. Decarbonation of Hydrotalcite is promoted by DMF hydrolysis followed by neutralization of brucite-like layers through HCOO - intercalation. Translucent colloidal dispersion of LDH nanoparticles from the formate-containing phase was characterized by transmission electron (TEM) and atomic force (AFM) microscopies. The absence of (00l) reflection at X-ray diffraction (XRD) pattern for dried colloidal dispersion indicated delamination of Hydrotalcite. The restacked sample exhibited broad reflections and typical hydroxide ordered layers non-basal (110) diffraction peaks. A LDH-HCOO - material was also prepared and characterized by FTIR and FT-Raman spectroscopies. Decarbonation and exfoliation of Hydrotalcite in N,N-dimethylformamide-ethanol mixed solvent provide an interesting method for preparation of new intercalated LDH materials. - Graphical abstract: Hydrotalcite suspended in 1:1 (v/v) N,N-dimethylformamide-ethanol solvent mixture, at ambient temperature, undergoes decarbonation and exfoliation. The process is promoted by DMF hydrolysis. Restacking of LDH layers is achieved by evaporating the solvent

  15. 40 CFR Table 6 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in the following... type Average organic HAP mass fraction Typical organic HAP, percent by mass Aliphatic b 0.03 1% xylene...

  16. Organic solvent topical report

    International Nuclear Information System (INIS)

    COWLEY, W.L.

    1999-01-01

    This report provides the basis for closing the organic solvent safety issue. Sufficient information is presented to conclude that risk posed by an organic solvent fire is within risk evaluation guidelines. This report updates information contained in Analysis of Consequences of Postulated Solvent Fires in Hanford Site Waste Tanks. WHC-SD-WM-CN-032. Rev. 0A (Cowley et al. 1996). However, this document will not replace Cowley et al (1996) as the primary reference for the Basis for Interim Operation (BIO) until the recently submitted BIO amendment (Hanson 1999) is approved by the US Department of Energy. This conclusion depends on the use of controls for preventing vehicle fuel fires and for limiting the use of flame cutting in areas where hot metal can fall on the waste surface.The required controls are given in the Tank Waste Remediation System Technical Safety Requirements (Noorani 1997b). This is a significant change from the conclusions presented in Revision 0 of this report. Revision 0 of this calcnote concluded that some organic solvent fire scenarios exceeded risk evaluation guidelines, even with controls imposed

  17. Organic solvent topical report

    Energy Technology Data Exchange (ETDEWEB)

    COWLEY, W.L.

    1999-05-13

    This report provides the basis for closing the organic solvent safety issue. Sufficient information is presented to conclude that risk posed by an organic solvent fire is within risk evaluation guidelines. This report updates information contained in Analysis of Consequences of Postulated Solvent Fires in Hanford Site Waste Tanks. WHC-SD-WM-CN-032. Rev. 0A (Cowley et al. 1996). However, this document will not replace Cowley et al (1996) as the primary reference for the Basis for Interim Operation (BIO) until the recently submitted BIO amendment (Hanson 1999) is approved by the US Department of Energy. This conclusion depends on the use of controls for preventing vehicle fuel fires and for limiting the use of flame cutting in areas where hot metal can fall on the waste surface.The required controls are given in the Tank Waste Remediation System Technical Safety Requirements (Noorani 1997b). This is a significant change from the conclusions presented in Revision 0 of this report. Revision 0 of this calcnote concluded that some organic solvent fire scenarios exceeded risk evaluation guidelines, even with controls imposed.

  18. Cooperative effects in the structuring of fluoride water clusters: Ab initio hybrid quantum mechanical/molecular mechanical model incorporating polarizable fluctuating charge solvent

    Science.gov (United States)

    Bryce, Richard A.; Vincent, Mark A.; Malcolm, Nathaniel O. J.; Hillier, Ian H.; Burton, Neil A.

    1998-08-01

    A new hybrid quantum mechanical/molecular mechanical model of solvation is developed and used to describe the structure and dynamics of small fluoride/water clusters, using an ab initio wave function to model the ion and a fluctuating charge potential to model the waters. Appropriate parameters for the water-water and fluoride-water interactions are derived, with the fluoride anion being described by density functional theory and a large Gaussian basis. The role of solvent polarization in determining the structure and energetics of F(H2O)4- clusters is investigated, predicting a slightly greater stability of the interior compared to the surface structure, in agreement with ab initio studies. An extended Lagrangian treatment of the polarizable water, in which the water atomic charges fluctuate dynamically, is used to study the dynamics of F(H2O)4- cluster. A simulation using a fixed solvent charge distribution indicates principally interior, solvated states for the cluster. However, a preponderance of trisolvated configurations is observed using the polarizable model at 300 K, which involves only three direct fluoride-water hydrogen bonds. Ab initio calculations confirm this trisolvated species as a thermally accessible state at room temperature, in addition to the tetrasolvated interior and surface structures. Extension of this polarizable water model to fluoride clusters with five and six waters gave less satisfactory agreement with experimental energies and with ab initio geometries. However, our results do suggest that a quantitative model of solvent polarization is fundamental for an accurate understanding of the properties of anionic water clusters.

  19. Ellipsometry-based combination of isothermal sorption-desorption measurement and temperature programmed desorption technique: A probe for interaction of thin polymer films with solvent vapor

    Science.gov (United States)

    Efremov, Mikhail Yu.; Nealey, Paul F.

    2018-05-01

    An environmental chamber equipped with an in situ spectroscopic ellipsometer, programmatic vapor pressure control, and variable temperature substrate holder has been designed for studying polymer coating behavior during an exposure to a solvent vapor and also for probing the residual solvent in the film afterwards. Both sorption-desorption cycle at a constant temperature and temperature programmed desorption (TPD) of the residual solvent manifest themselves as a change of the film thickness. Monitoring of ellipsometric angles of the coating allows us to determine the thickness as a function of the vapor pressure or sample temperature. The solvent vapor pressure is precisely regulated by a computer-controlled pneumatics. TPD spectra are recorded during heating of the film in an oil-free vacuum. The vapor pressure control system is described in detail. The system has been tested on 6-170 nm thick polystyrene, poly(methyl methacrylate), and poly(2-vinyl pyridine) films deposited on silicon substrates. Liquid toluene, water, ethanol, isopropanol, cyclohexane, 1,2-dichloroethane, and chlorobenzene were used to create a vapor atmosphere. Typical sorption-desorption and TPD curves are shown. The instrument achieves sub-monolayer sensitivity for adsorption studies on flat surfaces. Polymer-solvent vapor systems with strong interaction demonstrate characteristic absorption-desorption hysteresis spanning from vacuum to the glass transition pressure. Features on the TPD curves can be classified as either glass transition related film contraction or low temperature broad contraction peak. Typical absorption-desorption and TPD dependencies recorded for the 6 nm thick polystyrene film demonstrate the possibility to apply the presented technique for probing size effects in extremely thin coatings.

  20. Finite-Geometry and Polarized Multiple-Scattering Corrections of Experimental Fast- Neutron Polarization Data by Means of Monte Carlo Methods

    Energy Technology Data Exchange (ETDEWEB)

    Aspelund, O; Gustafsson, B

    1967-05-15

    After an introductory discussion of various methods for correction of experimental left-right ratios for polarized multiple-scattering and finite-geometry effects necessary and sufficient formulas for consistent tracking of polarization effects in successive scattering orders are derived. The simplifying assumptions are then made that the scattering is purely elastic and nuclear, and that in the description of the kinematics of the arbitrary Scattering {mu}, only one triple-parameter - the so-called spin rotation parameter {beta}{sup ({mu})} - is required. Based upon these formulas a general discussion of the importance of the correct inclusion of polarization effects in any scattering order is presented. Special attention is then paid to the question of depolarization of an already polarized beam. Subsequently, the afore-mentioned formulas are incorporated in the comprehensive Monte Carlo program MULTPOL, which has been designed so as to correctly account for finite-geometry effects in the sense that both the scattering sample and the detectors (both having cylindrical shapes) are objects of finite dimensions located at finite distances from each other and from the source of polarized fast-neutrons. A special feature of MULTPOL is the application of the method of correlated sampling for reduction of the standard deviations .of the results of the simulated experiment. Typical data of performance of MULTPOL have been obtained by the application of this program to the correction of experimental polarization data observed in n + '{sup 12}C elastic scattering between 1 and 2 MeV. Finally, in the concluding remarks the possible modification of MULTPOL to other experimental geometries is briefly discussed.