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Sample records for tetrahydrofuran

  1. Stereoselective tetrahydrofuran synthesis

    OpenAIRE

    Shaw, Duncan Edward

    1993-01-01

    This thesis begins in Chapter One with a discussion of the role of electrophilic cyclisation in the synthesis of tetrahydrofurans. Chapter Two begins with a discussion of the synthesis of iodo-olactones, by the iodolactonisation of β-silyloxy-δ-alkenoic acids (Scheme A). It will show how the potential of this chemistry has been expanded by proving the absolute stereochemistry at the iodine centre. Chapter Two goes on to consider the stereospecific synthesis of 2,3,5-trisubstituted iodo-te...

  2. Positron scattering from 3-hydroxy-tetrahydrofuran

    Energy Technology Data Exchange (ETDEWEB)

    Zecca, Antonio; Chiari, Luca [Department of Physics, University of Trento, I-38050 Povo, Trento (Italy); Sarkar, Anindya [Bangabasi Morning College, 19 RC Sarani, Kolkata 700 009 (India); Brunger, Michael J [ARC Center for Antimatter-Matter Studies, School of Chemistry, Physics and Earth Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia)

    2008-04-28

    We report on the first measurements of total cross sections for positron scattering from the important bio-molecule 3-hydroxy-tetrahydrofuran. In this case the energy range of our work is 0.4-18.4 eV. While there are currently no theoretical data against which we can compare these results, a comparison with corresponding measurements for the geometrically similar species tetrahydrofuran is made. This comparison enables us to infer information on the role that the conformers of 3-hydroxy-tetrahydrofuran play in the scattering process.

  3. Solution Characterization of Poly(isobornyl Methacrylate) in Tetrahydrofuran

    Science.gov (United States)

    1994-06-15

    solutions of poly( isobornyl meth- acrylate ) (PIMA) in tetrahydrofuran (THF) were characterized by using viscosity, static, and dynamic light scattering...dilute aolutions of poly ( isobornyl meth- acrylate ) (PIMA) in tetrahydrofuran (THF) were characterized by using viscosity, static, and dynamic light...FUNDING NUMBERS Solution Characterization of Poly( isobornyl Methacrylat #313H030in Tetrahydrofuran Kenneth J. Wynne X.Q. Zhang and C.H. Wang 7. PERFORMING

  4. New adjacent Bis-tetrahydrofuran Annonaceous acetogenins from Annona muricata.

    Science.gov (United States)

    Chang, Fang-Rong; Liaw, Chih-Chuang; Lin, Chih-Yuan; Chou, Chi-Jung; Chiu, Hui-Fen; Wu, Yang-Chang

    2003-03-01

    Bioactivity-guided fractionation led to the isolation of two new Annonaceous acetogenins, annocatacin A ( 1). and annocatacin B ( 2). from the seeds and the leaves, respectively, of Annona muricata. Compounds 1 and 2 are the first examples where the adjacent bis-tetrahydrofuran ring system is located at C-15. The new structures were elucidated and characterized by spectral and chemical methods. Both Annonaceous acetogenins 1 and 2 showed significant in vitro cytotoxicity toward the human hepatoma cell lines, Hep G2 and 2,2,15, and were compared with the known adjacent bis-tetrahydrofuran acetogenins, neoannonin ( 3). desacetyluvaricin ( 4). bullatacin ( 5). asimicin ( 6). annoglaucin ( 7). squamocin ( 8). and rollimusin ( 9).

  5. Reaction of chlorine radical with tetrahydrofuran: a theoretical investigation on mechanism and reactivity in gas phase.

    Science.gov (United States)

    Begum, Samiyara; Subramanian, Ranga

    2014-06-01

    Reaction of chlorine (Cl) radical with heterocyclic saturated ether, tetrahydrofuran has been studied. The detailed reactivity and mechanism of this reaction is analyzed using hybrid density functional theory (DFT), B3LYP and BB1K methods, and aug-cc-pVTZ basis set. To explore the mechanism of the reaction of tetrahydrofuran with Cl radical, four possible sites of hydrogen atom (H) abstraction pathways in tetrahydrofuran were analyzed. The barrier height and rate constants are calculated for the four H-abstraction channels. The BB1K calculated rate constant for α-axial H-abstraction is comparable with the experimentally determined rate constant. It reflects that α-axial H-abstraction is the main degradation pathway of tetrahydrofuran with Cl radical. DFT-based reactivity descriptors are also calculated and these values describe α-axial H-abstraction as the main reaction channel.

  6. Synthesis, Spectral Characterization and biological activity of N-Substituted Derivatives of Tetrahydrofuran-2-ylmethylamine

    OpenAIRE

    Aziz-ur-Rehman,; Rasool, S.; M. A. Abbasi; Khan, K M; Ahmad, I; Afzal, S.

    2014-01-01

    Tetrahydrofuran-2-ylmethylamine (1) was subjected to condensation reaction with 4-chlorobenzenesulfonyl chloride (2) in a mild basic medium to synthesize N-(tetrahydrofuran-2-ylmethyl)-4-chlorobenzenesulfonamide (3). A series of N-substituted derivatives, 5a-f, were synthesized by condensing alkyl/aralkyl halides, 4a-f, with 3 under polar aprotic conditions using sodium hydride activator. The spectral characterization of all the molecules included IR, 1H-NMR and EI-MS data. The biological act...

  7. [Characteristics of tetrahydrofuran degradation by Pseudomonas oleovorans DT4].

    Science.gov (United States)

    Zhou, Yu-Yang; Chen, Dong-Zhi; Jin, Xiao-Jun; Chen, Jian-Meng; He, Jie

    2011-01-01

    A tetrahydrofuran (THF)-degrading strain Pseudomonas oleovorans DT4 was isolated from the activated sludge of a pharmaceutical plant. P. oleovorans DT4 was able to utilize THF as the sole carbon and energy source under aerobic condition. 5 mmol/L of THF could be completely degraded by 3.2 mg/L inoculums of P. oleovorans DT4 in 14 h at pH 7.2 and 30 degrees C, with the cells concentration increasing to 188.6 mg/L. After the complete consumption of THF, no TOC could be detected but IC reached the stable value of about 46 mg/L, with pH decreasing to 6.54, which indicated that the substance was totally mineralized by P. oleovorans DT4. The optimum conditions for THF biodegradation in shaking flasks were pH 7.5 and temperature 37 degrees C, respectively. Results from the oxygen control experiments revealed that the oxygen supply by shaking was the satisfactory growth condition. Additionally, as the important elements for DT4, Mg2+ and Ca2+ at concentrations of 0.80 mmol/L and 0.20 mmol/L, respectively, were suitable for THF degradation. All the results contribute to the efficient bioremediation for the THF contaminated.

  8. Biotransformation of a tetrahydrofuran lignan by the endophytic fungus Phomopsis Sp

    Energy Technology Data Exchange (ETDEWEB)

    Verza, Michelle; Arakawa, Nilton S.; Lopes, Norberto P.; Pupo, Monica T.; Said, Suraia; Carvalho, Ivone [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Ciencias Farmaceuticas; Kato, Massuo J. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica]. E-mail: carronal@usp.br

    2009-07-01

    The biotrasformation of the tetrahydrofuran lignan, (-)-grandisin, by the endophitic fungus Phomopsis sp, obtained from Viguiera arenaria, led to the formation of a new compound determined as 3,4-dimethyl-2- (4'-hydroxy-3',5'-dimethoxyphenyl)-5-methoxy-tetrahydrofuran. The metabolite was evaluated against the parasite Trypanosoma cruzi, the causative agent of Chagas's disease, and showed a trypanocidal activity (IC{sub 50} 9.8 {mu}mol L{sup -1}) similar to the natural precursor (IC{sub 50} 3.7 {mu}mol L{sup -1}). (author)

  9. Transition-metal triflate catalyzed unprecedented formation of oxime ketals of tetrahydrofuran via C-H functionalization

    Science.gov (United States)

    Shafi, Syed

    2015-02-01

    Benzaldehyde O-tetrahydrofuran-2-yl oximes were formed through the C-H functionalization from the reaction between benzaldoximes and aqueous tetrahydrofuran catalyzed by water tolerant transition metal triflates (Lewis acids). The formation of oxime ketal has been confirmed from 2D NMR analysis (HMBC and HSQC studies).

  10. Trehalose promotes Rhodococcus sp. strain YYL colonization in activated sludge under tetrahydrofuran (THF) stress.

    Science.gov (United States)

    He, Zhixing; Zhang, Kai; Wang, Haixia; Lv, Zhenmei

    2015-01-01

    Few studies have focused on the role of compatible solutes in changing the microbial community structure in bioaugmentation systems. In this study, we investigated the influence of trehalose as a biostimulant on the microbial community in tetrahydrofuran (THF)-treated wastewater bioaugmentation systems with Rhodococcus sp. YYL. Functional gene profile changes were used to study the variation in the microbial community. Soluble di-iron monooxygenases (SDIMO), particularly group-5 SDIMOs (i.e., tetrahydrofuran and propane monooxygenases), play a significant role in the initiation of the ring cleavage of tetrahydrofuran. Group-5 SDIMOs genes are enriched upon trehalose addition, and exogenous tetrahydrofuran monooxygenase (thmA) genes can successfully colonize bioaugmentation systems. Cytochrome P450 monooxygenases (P450s) have a significant role in catalyzing the region- and stereospecific oxidation of non-activated hydrocarbons, and THF was reported to inhibit P450s in the environment. The CYP153 family was chosen as a representative P450 to study the inhibitory effects of THF. The results demonstrated that CYP153 family genes exhibited significant changes upon THF treatment and that trehalose helped maintain a rich diversity and high abundance of CYP153 family genes. Biostimulation with trehalose could alleviate the negative effects of THF stress on microbial diversity in bioaugmentation systems. Our results indicated that trehalose as a compatible solute plays a significant role for environmental strains under extreme conditions.

  11. Modelling of tetrahydrofuran promoted gas hydrate systems for carbon dioxide capture processes

    DEFF Research Database (Denmark)

    Herslund, Peter Jørgensen; Thomsen, Kaj; Abildskov, Jens

    2014-01-01

    . CPA descriptions are adjusted when needed by correlation of binary parameters in the applied mixing- and combining rules. Kihara cell potential parameters in the hydrate model are regressed for the three hydrate formers, tetrahydrofuran, carbon dioxide and nitrogen. The developed model provides highly...

  12. Fukui Function Analysis and Optical, Electronic, and Vibrational Properties of Tetrahydrofuran and Its Derivatives: A Complete Quantum Chemical Study

    Directory of Open Access Journals (Sweden)

    Apoorva Dwivedi

    2015-01-01

    Full Text Available The spectroscopic, optical, and electronic properties of tetrahydrofuran and its derivatives were investigated by FTIR techniques. We have done a comparative study of tetrahydrofuran and its derivatives with B3LYP with 6-311 G (d, p as the basis set. Here we have done a relative study of their structures, vibrational assignments, and thermal, electronic, and optical properties of ttetrahydrofuran and its derivatives. We have plotted frontier orbital HOMO-LUMO surfaces and molecular electrostatic potential surfaces to explain the reactive nature of tetrahydrofuran and its derivatives.

  13. 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.

  14. iso-Petromyroxols: Novel Dihydroxylated Tetrahydrofuran Enantiomers from Sea Lamprey (Petromyzon marinus

    Directory of Open Access Journals (Sweden)

    Ke Li

    2015-03-01

    Full Text Available An enantiomeric pair of new fatty acid-derived hydroxylated tetrahydrofurans, here named iso-petromyroxols, were isolated from sea lamprey larvae-conditioned water. The relative configuration of iso-petromyroxol was elucidated with 1D and 2D NMR spectroscopic analyses. The ratio of enantiomers (er in the natural sample was measured by chiral-HPLC-MS/MS to be ca. 3:1 of (–- to (+-antipodes.

  15. Copolymerization of Carbon–carbon Double-bond Monomer (Styrene with Cyclic Monomer (Tetrahydrofuran

    Directory of Open Access Journals (Sweden)

    Sari Fouad

    2012-12-01

    Full Text Available We reported in this work that the cationic copolymerization in one step takes place between carbon–carbon double-bond monomer styrene with cyclic monomer tetrahydrofuran. The comonomers studied belong to different families: vinylic and cyclic ether. The reaction is initiated with maghnite-H+ an acid exchanged montmorillonite as acid solid ecocatalyst. Maghnite-H+ is already used as catalyst for polymerization of many vinylic and heterocyclic monomers. The oxonium ion of tetrahydrofuran and carbonium ion of styrene propagated the reaction of copolymerization. The acetic anhydride is essential for the maintenance of the ring opening of tetrahydrofuran and the entry in copolymerization. The temperature was kept constant at 40°C in oil bath heating for 6 hours. A typical reaction product was analyzed by 1H-NMR, 13C-NMR and IR and the formation of the copolymer was confirmed. The reaction was proved by matched with analysis. The maghnite-H+ allowed us to obtain extremely pure copolymer in good yield by following a simples operational conditions. Copyright © 2012 by BCREC UNDIP. All rights reservedReceived: 29th October 2012; Revised: 29th November 2012; Accepted: 29th November 2012[How to Cite: S. Fouad, M.I. Ferrahi, M. Belbachir. (2012. Copolymerization of Carbon–carbon Double-bond Monomer (Styrene with Cyclic Monomer (Tetrahydrofuran. Bulletin of Chemical Reaction Engineering & Catalysis, 7(2: 165-171. (doi:10.9767/bcrec.7.2.4074.165-171][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.2.4074.165-171 ] | View in 

  16. Thermodynamic Functions of Solvation of Hydrocarbons, Noble Gases, and Hard Spheres in Tetrahydrofuran-Water Mixtures.

    Science.gov (United States)

    Sedov, I A; Magsumov, T I

    2015-07-16

    Thermodynamic solvation properties of mixtures of water with tetrahydrofuran at 298 K are studied. The Gibbs free energies and enthalpies of solvation of n-octane and toluene are determined experimentally. For molecular dynamics simulations of the binary solvent, we have modified a TraPPE-UA model for tetrahydrofuran and combined it with the SPC/E potential for water. The excess thermodynamic functions of neon, xenon, and hard spheres with two different radii are calculated using the particle insertion method. Simulated and real systems share the same characteristic trends for the thermodynamic functions. A maximum is present on dependencies of the enthalpy of solvation from the composition of solvent at 70-90 mol % water, making it higher than in both of the cosolvents. It is caused by a high enthalpy of cavity formation in the mixtures rich with water due to solvent reorganization around the cavity, which is shown by calculation of the enthalpy of solvation of hard spheres. Addition of relatively small amounts of tetrahydrofuran to water effectively suppresses the hydrophobic effect, leading to a quick increase of both the entropy and enthalpy of cavity formation and solvation of low polar molecules.

  17. Trehalose promotes Rhodococcus sp. strain YYL colonization in activated sludge under tetrahydrofuran (THF stress

    Directory of Open Access Journals (Sweden)

    Zhixing eHe

    2015-05-01

    Full Text Available Few studies have focused on the role of compatible solutes in changing the microbial community structure in bioaugmentation systems. In this study, we investigated the influence of trehalose as a biostimulant on the microbial community in THF-treated wastewater bioaugmentation systems with Rhodococcus sp. YYL. Functional gene profile changes were used to study the variation in the microbial community. Soluble di-iron monooxygenases (SDIMO, particularly group-5 SDIMOs (i.e., tetrahydrofuran and propane monooxygenases, play a significant role in the initiation of the ring cleavage of tetrahydrofuran. Group-5 SDIMOs genes are enriched upon trehalose addition, and exogenous tetrahydrofuran monooxygenase (thmA genes can successfully colonize bioaugmentation systems. Cytochrome P450 monooxygenases (P450s have a significant role in catalyzing the region- and stereospecific oxidation of non-activated hydrocarbons, and THF was reported to inhibit P450s in the environment. The CYP153 family was chosen as a representative P450 to study the inhibitory effects of THF. The results demonstrated that CYP153 family genes exhibited significant changes upon THF treatment and that trehalose helped maintain a rich diversity and high abundance of CYP153 family genes. Biostimulation with trehalose could alleviate the negative effects of THF stress on microbial diversity in bioaugmentation systems. Our results indicated that trehalose as a compatible solute plays a significant role for environmental strains under extreme conditions.

  18. Cross-linked poly(tetrahydrofuran) as promising sorbent for organic solvent/oil spill

    Energy Technology Data Exchange (ETDEWEB)

    Yati, Ilker; Ozan Aydin, Gulsah; Bulbul Sonmez, Hayal, E-mail: hayalsonmez@gtu.edu.tr

    2016-05-15

    Highlights: • Poly(tetrahydrofuran) based sorbents were prepared. • PTHF sorbents demonstrate reusability at least for ten times. • PTHF based sorbents show fast and quick absorption-desorption process. • 19 g of oil can be absorbed by 1 g of PTHF based sorbent. - Abstract: In this study, a series of different molecular weights of poly(tetrahydrofuran) (PTHF), which is one of the most important commercial polymers around the world, was condensed with tris[3-(trimethoxysilyl)propyl]isocyanurate (ICS) to generate a cross-linked 3-dimensional network in order to obtain organic solvent/oil sorbents having high swelling capacity. The prepared sorbents show high and fast swelling capacity in oils such as dichloromethane (DCM), tetrahydrofuran (THF), acetone, t-butyl methyl ether (MTBE), gasoline, euro diesel, and crude oil. The recovery of the absorbed oils from contaminated surfaces, especially from water, and the regeneration of the sorbents after several applications are effective. The characterization and thermal properties of the sorbents are identified by Fourier transform infrared spectroscopy (FTIR), solid-state {sup 13}C and {sup 29}Si cross-polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and thermal gravimetric analyses (TGA), respectively. The new usage area of PTHF is emerged by the preparation of PTHF-based network structure with high oil absorption capacity and having excellent reusability as an oil absorbent for the removal of organic liquids from the spill site.

  19. Key fuel properties and engine performances of diesel-ethanol blends, using tetrahydrofuran as surfactant additive

    Science.gov (United States)

    Molea, A.; Visuian, P.; Barabás, I.; Suciu, R. C.; Burnete, N. V.

    2017-10-01

    In this paper there were presented researches related to preparation and characterization of physicochemical properties of diesel-ethanol blends stabilized with tetrahydrofuran as surfactant, in order to be used as fuels in compression ignition engines. The main spray characteristics and engine performances of these blends were evaluated by using AVL Fire software. In the first stage of the studies, commercial diesel was mixed with ethanol, in different concentrations (between 2% and 15% v/v), followed by the addition of tetrahydrofuran (THF) until the blends were miscible, i.e. the blends were stabilized. The experiments were done at room temperature (22 °C). The obtained blends were characterized in order to determine the chemical composition and physicochemical properties, i.e. density, kinematic viscosity, surface tension. UV-Vis spectroscopy was utilized in order to determine a semi-quantitative evaluation regarding the chemical composition of the prepared blends and chemical interaction between diesel, ethanol and THF. Based on the determined properties, the fuel spray characteristics, engine performances and emission characteristics were evaluated by simulation using the AVL Fire software. The obtained results regarding physicochemical properties of blends were compared with diesel. Some improvements were observed when operating with the prepared blends compared to diesel with respect to engine performances and emission characteristics. Based on physicochemical evaluation and computer simulation, it was demonstrated that diesel-ethanol-tetrahydrofuran blends can be used as alternative fuel in compression ignition engines.

  20. An experimental and theoretical kinetic study of the reaction of OH radicals with tetrahydrofuran

    KAUST Repository

    Giri, Binod

    2016-06-24

    Tetrahydrofuran (CHO, THF) and its alkylated derivatives of the cyclic ether family are considered to be promising future biofuels. They appear as important intermediates during the low-temperature oxidation of conventional hydrocarbon fuels and of heavy biofuels such as long-chain fatty acid methyl esters. The reaction of tetrahydrofuran with OH radicals was investigated in a shock tube, over a temperature range of 800-1340 K and at pressures near 1.5 bar. Hydroxyl radicals were generated by the rapid thermal decomposition of tert-butyl hydroperoxide, and a UV laser absorption technique was used to monitor the mole fraction of OH radicals. High-level CCSD(T)/cc-pV(D,T)Z//MP2/aug-cc-pVDZ quantum chemical calculations were performed to explore the chemistry of the THF+OH reaction system. Our calculations reveal that the THF+OH (R1) reaction proceeds via either direct or indirect H-abstraction from various sites, leading to the formation of tetrahydrofuran-2-yl (THF-R2) or tetrahydrofuran-3-yl (THF-R3) radicals and water. Theoretical kinetic analysis revealed that both channels are important under conditions relevant to combustion. To our knowledge, this is the first direct experimental and theoretical kinetic study of the reaction of tetrahydrofuran with OH radicals at high temperatures. The following theoretical rate expressions (in units of cmmols) are recommended for combustion modeling in the temperature range 800-1350 K: . k1(T)=4.11×1040.16em0ex(TK)2.69exp(1316.80.16em0exKT)2.em0ex0.16em0ex(THF+OH→Products) . k2(T)=6.930.16em0ex×10110.16em0ex(TK)0.41exp(-106.80.16em0exKT)2.em0ex0.16em0ex(THF+OH→THF-R20.16em0ex+H2O) . k3(T)=4.120.16em0ex×1030.16em0ex(TK)3.02exp(456.90.16em0exKT)2.em0ex0.16em0ex(THF+OH→THF-R30.16em0ex+H2O) . .

  1. The application of hydrogen-palladium electrode for potentiometric acid-base determinations in tetrahydrofuran

    Directory of Open Access Journals (Sweden)

    Jokić Anja B.

    2013-01-01

    Full Text Available The application of the hydrogen-palladium electrode (H2/Pd as the indicator electrode for the determination of relative acidity scale (Es, mV of tetrahydrofuran (THF and the potentiometric titrations of acids in this solvent was investigated. The relative acidity scale tetrahydrofuran was determined from the difference half-neutralization potentials of perchloric acid and tetrabutylammonium hydroxide (TBAH, which were measured by using both H2/Pd-SCE and glass-SCE electrode pairs. The experimentally obtained value of Es scale THF with a H2/Pd-SCE electrode pair was 1155 mV, and those obtained with glass-SCE electrode pair 880 mV. By using a H2/Pd indicator electrode, the individual acids (benzoic acid, palmitic acid, maleic acid, acetyl acetone, α-naphthol and two component acid mixtures (benzoic acid + α-naphthol, palmitic acid + α-naphthol, maleic acid + α-naphthol and maleic acid + ftalic acid were titrated with a standard solution of TBAH. In addition, sodium methylate and potassium hydroxide proved to be very suitable titrating agents for titrating of the individual acids and the acids in mixtures, respectively. The relative error of the determination of acids in mixture was less than 3%. The results are in agreement with those obtained by a conventional glass electrode. The advantages of H2/Pd electrode over a glass electrode in potentiometric acid-base determinations in tetrahydrofuran lie in the following: this electrode gives wider relative acidity scale THF, higher the potential jumps at the titration end-point and relatively fast response time; furthermore, it is very durable, simple to prepare and can be used in the titrations of small volumes. [Projekat Ministarstva nauke Republike Srbije, br.172051

  2. Biodegradation Kinetics of Tetrahydrofuran, Benzene, Toluene, and Ethylbenzene as Multi-substrate by Pseudomonas oleovorans DT4

    Directory of Open Access Journals (Sweden)

    Dong-Zhi Chen

    2014-12-01

    Full Text Available The biodegradation kinetics of tetrahydrofuran, benzene (B, toluene (T, and ethylbenzene (E were systematically investigated individually and as mixtures by a series of aerobic batch degradation experiments initiated by Pseudomonas oleovorans DT4. The Andrews model parameters, e.g., maximum specific growth rates (μmax, half saturation, and substrate inhibition constant, were obtained from single-substrate experiments. The interaction parameters in the sum kinetics model (SKIP were obtained from the dual substrates. The μmax value of 1.01 for tetrahydrofuran indicated that cell growth using tetrahydrofuran as carbon source was faster than the growth on B (μmax, B = 0.39 or T (μmax, T = 0.39. The interactions in the dual-substrate experiments, including genhancement, inhibition, and co-metabolism, in the mixtures of tetrahydrofuran with B or T or E were identified. The degradation of the four compounds existing simultaneously could be predicted by the combination of SKIP and co-metabolism models. This study is the first to quantify the interactions between tetrahydrofuran and BTE.

  3. Biodegradation kinetics of tetrahydrofuran, benzene, toluene, and ethylbenzene as multi-substrate by Pseudomonas oleovorans DT4.

    Science.gov (United States)

    Chen, Dong-Zhi; Ding, Yun-Feng; Zhou, Yu-Yang; Ye, Jie-Xu; Chen, Jian-Meng

    2014-12-31

    The biodegradation kinetics of tetrahydrofuran, benzene (B), toluene (T), and ethylbenzene (E) were systematically investigated individually and as mixtures by a series of aerobic batch degradation experiments initiated by Pseudomonas oleovorans DT4. The Andrews model parameters, e.g., maximum specific growth rates (μmax), half saturation, and substrate inhibition constant, were obtained from single-substrate experiments. The interaction parameters in the sum kinetics model (SKIP) were obtained from the dual substrates. The μmax value of 1.01 for tetrahydrofuran indicated that cell growth using tetrahydrofuran as carbon source was faster than the growth on B (μmax, B = 0.39) or T (μmax, T = 0.39). The interactions in the dual-substrate experiments, including genhancement, inhibition, and co-metabolism, in the mixtures of tetrahydrofuran with B or T or E were identified. The degradation of the four compounds existing simultaneously could be predicted by the combination of SKIP and co-metabolism models. This study is the first to quantify the interactions between tetrahydrofuran and BTE.

  4. [Disulfanediylbis(ferrocenylthiophosphinato-κ2O,O]titanocene tetrahydrofuran trisolvate

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    Mehmet Karakus

    2012-04-01

    Full Text Available The title compound, [Fe2Ti(C5H54(C10H8O2P2S4]·3C4H8O, contains a central seven-membered TiO2P2S2 ring with a very similar geometry compared to the derivative showing anisyl instead of ferrocenyl substituents, the Ti—O distance being marginally longer for the anisyl derivative. Two tetrahydrofuran solvent molecules are each disordered on a twofold axis.

  5. NMR identification of the terminal groups of the telomers of tetrafluoroethylene with tetrahydrofuran

    Science.gov (United States)

    Kim, I. P.; Kunitsa, A. A.; Chernyak, A. V.

    2013-11-01

    1H, 13C, and 19F high-resolution NMR spectra with heteronuclear spin-spin decoupling and without it were recorded for identification of the terminal groups of oligomers obtained by radical polymerization of tetrafluroethylene (TFE) in tetrahydrofuran (THF) solutions. The analysis of the spectra and their comparison with the quantum-chemically calculated spectra of possible polymerization products led to the conclusion that the terminal groups of oligomers are the α radical of THF and the hydrogen atom. The structure of oligomers found in this study opens up an opportunity of synthesizing from them polymers consisting of a flexible main chain with substituents in the form of rigid perfluorinated rods.

  6. Tandem Olefin Metathesis/Oxidative Cyclization: Synthesis of Tetrahydrofuran Diols from Simple Olefins.

    Science.gov (United States)

    Dornan, Peter K; Lee, Daniel; Grubbs, Robert H

    2016-05-25

    A tandem olefin metathesis/oxidative cyclization has been developed to synthesize 2,5-disubstituted tetrahydrofuran (THF) diols in a stereocontrolled fashion from simple olefin precursors. The ruthenium metathesis catalyst is converted into an oxidation catalyst in the second step and is thus responsible for both catalytic steps. The stereochemistry of the 1,5-diene intermediate can be controlled through the choice of catalyst and the type of metathesis conducted. This olefin stereochemistry then controls the THF diol stereochemistry through a highly stereospecific oxidative cyclization.

  7. 1,1,1-Tris(dimethylamino-2-[tris(dimethylaminophosphoranylidene]diphosphinium tetraphenylborate tetrahydrofuran monosolvate

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    Bobby D. Ellis

    2014-06-01

    Full Text Available In the tetrahydrofuran solvate of the title salt, C12H36N6P3+·C24H20B−·C4H8O, the cation features short P—P bond lengths [2.1111 (11 and 2.1364 (10 Å] and a distinctly bent P—P—P angle [104.67 (4°] that confirm that the molecule is not allene-like. In the crystal, the solvent molecule is linked to the cation via a weak C—H...O hydrogen bond.

  8. Third derivative thermodynamic quantities of aqueous tetrahydrofuran at 25 degrees C

    DEFF Research Database (Denmark)

    Westh, Peter; Yoshida, Koh; Inaba, Akira

    2015-01-01

    We measured the excess chemical potential, μΕTHF, the excess partial molar enthalpy and entropy of solute tetrahydrofuran (THF), HETHF and SETHF, in THF–H2O at 25 °C. Using these second derivatives of G, we graphically evaluated the third derivative quantities; the enthalpic, entropic THF......THFSV, another third derivative quantity. By comparing the mole fraction dependence patterns of these third derivative quantities between the present THF–H2O with what we thought to be the weakest member of a hydrophobic mono-ol series, methanol (ME), we suggest that in spite of its larger non-polar surface area...

  9. catena-Poly[[(tetrahydrofuran-κOlithium(I]-bis(μ-trimethylsilanolato-κ2O:O-gallium(III-bis(μ-trimethylsilanolato-κ2O:O-[(tetrahydrofuran-κOlithium(I]-μ-bromido

    Directory of Open Access Journals (Sweden)

    Jerzy Pikies

    2010-10-01

    Full Text Available The title chain polymer compound, [GaLi2Br(C3H9OSi4(C4H8O2]n, was obtained in the reaction of GaBr3 with Me3SiOLi in toluene/tetrahydrofuran. The GaIII atom, located on a twofold rotation axis, is coordinated by four trimethylsilanolate ligands and has a distorted tetrahedral geometry. The LiI atom is four coordinated by one bridging Br atom located on an inversion centre, two trimethylsilanolate ligands and one tetrahydrofurane molecule in a distorted tetrahedral geometry. The polymeric chains extend along [001]. The tetrahydrofurane molecule is disordered over two positions with site-occupancy factors of 0.57 (2 and 0.43 (2.

  10. Inhalation developmental toxicology studies: Teratology study of tetrahydrofuran in mice and rats: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Mast, T.J.; Evanoff, J.J.; Stoney, K.H.; Westerberg, R.B.; Rommereim, R.L.; Weigel, R.J.

    1988-08-01

    Tetrahydrofuran (THF), a four-carbon cyclic ether, is widely used as an industrial solvent. Although it has been used in large quantities for many years, few long-term toxicology studies, and no reproductive or developmental studies, have been conducted on THF. This study addresses the potential for THF to cause developmental toxicity in rodents by exposing Sprague-Dawley rats and Swiss (CD-1) mice to 0, 600, 1800, or 5000 ppm tetrahydrofuran (THF) vapors, 6 h/day, 7 dy/wk. Each treatment group consisted of 10 virgin females (for comparison), and approx.33 positively mated rats or mice. Positively mated mice were exposed on days 6--17 of gestation (dg), and rats on 6--19 dg. The day of plug or sperm detection was designated as O dg. Body weights were obtained throughout the study period, and uterine and fetal body weights were obtained at sacrifice (rats, 20 dg; mice, 18 dg). Implants were enumerated and their status recorded and live fetuses were examined for gross, visceral, skeletal, and soft-tissue craniofacial defects. 27 refs., 6 figs., 23 tabs.

  11. Diaquabis(1,10-phenanthrolinenickel(II tetrakis(cyanido-κCnickelate(II tetrahydrofuran solvate monohydrate

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2010-10-01

    Full Text Available The title complex, [Ni(C12H8N22(H2O2][Ni(CN4]·C4H8O·H2O, consists of a cationic [Ni(C12H8N22(H2O2]2+ unit, an anionic [Ni(CN4]2− unit, one uncoordinated water and one tetrahydrofuran molecule. In the cationic unit, the Ni2+ atom is coordinated by four N atoms and two O atoms from two 1,10-phenanthroline ligands and two water molecules in a distorted octahedral coordination environment. In the anionic unit, the Ni2+ atom is in a square-planar coordination by four C atoms from four monodentate terminal cyanide ligands. O—H...N and O—H...O hydrogen bonds link neighboring cationic and anionic units, forming a three-dimensional supramolecular network. The interstitial tetrahydrofuran molecule is independently disordered over two sites in a 1:1 ratio.

  12. [3,3]-Sigmatropic rearrangement of boronated allylcyanates: a new route to α-aminoboronate derivatives and trisubstituted tetrahydrofurans.

    Science.gov (United States)

    Touchet, Sabrina; Macé, Aurélie; Roisnel, Thierry; Carreaux, François; Bouillon, Alexandre; Carboni, Bertrand

    2013-06-07

    [3,3]-Sigmatropic cyanate-isocyanate rearrangement provides a powerful tool for the preparation of α-isocyanato allylboronic esters, which can be further trapped with a variety of nucleophiles. Hydrogenation gave the corresponding α-aminoboronates derivatives while addition of aldehydes afforded homoallylic alcohols, (tetrahydrofuran-2-yl)carbamate, ether, or urea derivatives.

  13. Thermodynamic promotion of carbon dioxide-clathrate hydrate formation by tetrahydrofuran, cyclopentane and their mixtures

    DEFF Research Database (Denmark)

    Herslund, Peter Jørgensen; Thomsen, Kaj; Abildskov, Jens

    2013-01-01

    Gas clathrate hydrate dissociation pressures are reported for mixtures of carbon dioxide, water and thermodynamic promoters forming structure II hydrates.Hydrate (H)-aqueous liquid (Lw)-vapour (V) equilibrium pressures for the ternary system composed of water, tetrahydrofuran (THF), and carbon......) equilibrium data are presented for the ternary system of water-cyclopentane-carbon dioxide at temperatures ranging from 285.2K down to 275.5K.New four-phase H-Lw-La-V equilibrium data for the quaternary system water-THF-cyclopentane-carbon dioxide are presented in the temperature range from 275.1K to 286.6K....... It is shown that upon adding THF to the pure aqueous phase to form a 4mass percent solution, the equilibrium pressure of the formed hydrates may be lowered compared to the ternary system of water, cyclopentane and carbon dioxide. © 2013 Elsevier Ltd....

  14. Synthesis of BaSO4 nanoparticles in a water-tetrahydrofuran system

    Science.gov (United States)

    Boguslavskii, L. I.; Buslaeva, T. M.; Fomichev, V. V.; Kopylova, E. V.; Kaplun, A. P.; Popenko, V. I.

    2015-02-01

    A highly nonequilibrium system of two miscible liquids is proposed as a generator of barium sulfate nanoparticles. A dynamic transition layer model developed in this work is used to explain the obtained results; according to this model, the smallest diameter of the resulting particles is determined by the size of the prephase associates formed in rotating Benard cells. It is hypothesized that the Benard cell-ambient solution interface has certain barrier properties, at least with respect to the new phase precursor's particles penetrating from outside. The effect of the H2O/tetrahydrofuran ratio on the size of particles and the shape of associates and nanocrystallites is studied. The dependence of the size of nanocrystalline particles on the above ratio is derived. A possible explanation is proposed for the dependence of the size of nanoparticles on the viscosity of a solvent.

  15. NMR studies of the conformation and motion of tetrahydrofuran in graphite intercalation compounds

    Energy Technology Data Exchange (ETDEWEB)

    Caplan, Daniel Franz [Univ. of California, Berkeley, CA (United States)

    1991-11-01

    The behavior of tetrahydrofuran (THF) molecules intercalated in graphite layers in compounds Cs(THF){sub 1.3}C{sub 24} and K(THF){sub 2.5}C{sub 24} was studied by proton NMR. The graphite layers in these compounds impose a uniform ordering on the THF molecules, giving rise to sharp NMR spectra. Experimental and simulated proton NMR spectra were used to investigate geometry, orientation and conformation of intercalated THF, and to determine whether pseudorotation, a large amplitude low-frequency vibration observed in gaseous THF, can also occur in the constrained environment provided by the graphite intercalation compounds. Deuterium and multiple quantum proton NMR spectra were also simulated in order to determine if these techniques could further refine the proton NMR results.

  16. [Biodegradation of tetrahydrofuran by combined immobilized of Pseudomonas oleovorans DT4].

    Science.gov (United States)

    Shao, Qian; Ye, Jie-Xu; Ouyang, Du-Juan; Chen, Jian-Meng; Chen, Dong-Zhi

    2013-08-01

    A new composite matrix, calcium alginate (CA) coupled with activated carbon fiber (ACF) was designed to immobilize the cells of Pseudomonas oleovorans DT4 for tetrahydrofuran (THF) degradation. The average removal rate of the CA-ACF immobilized cells reached 24.0 mg x (L x h)(-1) with an initial THF concentration of 360 mg x L(-1) when the concentration of CA and ACF was 3% and 1.5% respectively. The mechanical strength of the mobilized cells was also significantly improved with the addition of ACF. Compared to the free suspended cells, higher stable removal efficiency (more than 80%) of CA-ACF cells was detected under different conditions of temperature and pH. The feasibility of the newly designed matrix was also reflected by the repeated batch degradation which showed that the removal activity decreased insignificantly after 80 cycles with the modified reaction system (PNS).

  17. Complexation equilibria in tetrahydrofuran solutions of palladium(II) and lithium bromides

    Science.gov (United States)

    Putin, A. Yu.; Katsman, E. A.; Temkin, O. N.; Bruk, L. G.

    2017-04-01

    The solutions of palladium PdBr2 and lithium LiBr bromides in tetrahydrofuran (THF) at different concentrations were studied by UV-Vis spectroscopy. The data obtained were mathematically processed using various models. The best description was obtained with the model that includes the formation of four monomeric (PdBr+, PdBr2, PdBr 3 - , PdBr 4 2- ) and three dimeric (Pd2Br 2 2+ , Pd2Br4, Pd2Br 6 2- ) palladium complexes. The equilibrium constants of the monomer and dimer complexation stages and the extinction coefficients of the palladium complexes were calculated. The spectra of the individual monomer and dimer palladium complexes were calculated using this model.

  18. Measurement and correlation of isobaric vapor-liquid equilibrium for the binary system of cyclopentane and tetrahydrofuran

    OpenAIRE

    Yumei Li

    2014-01-01

    Isobaric vapor-liquid equilibrium (VLE) data for the cyclopentane and tetrahydrofuran (THF) system were measured at 101.3 kPa by using an equilibrium still. Thermodynamic consistency of the experimental data was confirmed by means of the Herington method. The experimental data were correlated and calculated by the Margules, Van Laar and Wilson activity-coefficient models, respectively. The Wilson and Van Laar activity-coefficient models are better than the Margules activity-coefficient model ...

  19. The combined effect of thermodynamic promoters tetrahydrofuran and cyclopentane on the kinetics of flue gas hydrate formation

    DEFF Research Database (Denmark)

    Daraboina, Nagu; von Solms, Nicolas

    2015-01-01

    Carbon dioxide (CO2) capture through hydrate crystallization is a promising method among the new approaches for mitigating carbon emissions into the atmosphere. In this work, we investigate a combination of tetrahydrofuran (THF) and cyclopentane (CP) on the kinetics of flue gas (CO2:20 mol %/N2...... of these two promoters is favorable both thermodynamically and kinetically for hydrate formation from flue gas....

  20. Three new anti-proliferative Annonaceous acetogenins with mono-tetrahydrofuran ring from graviola fruit (Annona muricata).

    Science.gov (United States)

    Sun, Shi; Liu, Jingchun; Kadouh, Hoda; Sun, Xiuxiu; Zhou, Kequan

    2014-06-15

    Bioassay-guided fractionation of the fruit powder of graviola (Annona muricata) yielded three novel compounds: muricins J, K, and L. The compounds are all C35 Annonaceous acetogenins with a mono-tetrahydrofuran ring and four hydroxyls. Their structures were elucidated by spectral methods and chemical modification after isolation via chromatographic techniques and HPLC purification. These three acetogenins demonstrated an antiproliferative against human prostate cancer PC-3 cells. Copyright © 2014. Published by Elsevier Ltd.

  1. Biodegradation Kinetics of Tetrahydrofuran, Benzene, Toluene, and Ethylbenzene as Multi-substrate by Pseudomonas oleovorans DT4

    OpenAIRE

    Dong-Zhi Chen; Yun-Feng Ding; Yu-Yang Zhou; Jie-Xu Ye; Jian-Meng Chen

    2014-01-01

    The biodegradation kinetics of tetrahydrofuran, benzene (B), toluene (T), and ethylbenzene (E) were systematically investigated individually and as mixtures by a series of aerobic batch degradation experiments initiated by Pseudomonas oleovorans DT4. The Andrews model parameters, e.g., maximum specific growth rates (? max), half saturation, and substrate inhibition constant, were obtained from single-substrate experiments. The interaction parameters in the sum kinetics model (SKIP) were obtai...

  2. An efficient and economical process for lignin depolymerization in biomass-derived solvent tetrahydrofuran.

    Science.gov (United States)

    Long, Jinxing; Zhang, Qi; Wang, Tiejun; Zhang, Xinghua; Xu, Ying; Ma, Longlong

    2014-02-01

    The depolymerization of renewable lignin for phenolic monomer, a versatile biochemical and precursor for biofuel, has attracted increasing attention. Here, an efficient base-catalyzed depolymerization process for this natural aromatic polymer is presented with cheap industrial solid alkali MgO and biomass-derived solvent tetrahydrofuran (THF). Results showed that more than 13.2% of phenolic monomers were obtained under 250°C for 15 min, because of the excellent lignin dissolution of THF and its promotion effect on the catalytic activity of MgO. Furthermore, comparison characterization on the raw material, products and residual solid using elemental analysis, FT-IR, TG-DSC, Py-GC-MS and chemo-physical absorption and desorption demonstrated that this base-catalyzed process can inhibit char formation significantly. Whereas, the fact that thermal repolymerization of oligomer on the pore and surface of catalyst resulting in the declination of the catalytic performance is responsible for the residue formation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Tetrahydrofuran as solvent in dental adhesives: cytotoxicity and dentin bond stability.

    Science.gov (United States)

    Fontes, Silvia Terra; Fernández, María Raquel; Ogliari, Fabrício Aulo; de Carvalho, Rodrigo Varella; de Moraes, Rafael Ratto; Pinto, Márcia Bueno; Piva, Evandro

    2013-01-01

    The aim of this study was to investigate the cytotoxicity and 1-year dentin bond stability of solvated etch-and-rinse dental adhesives based on tetrahydrofuran (THF), acetone, or ethanol, containing water or not. Seven primers were prepared using the following solvents: THF, acetone, ethanol, water, THF/water, acetone/water, and ethanol/water. Bovine dentin was used, and specimens for microtensile bond strength (μTBS) test were prepared. Specimens were tested after storage in distilled water for 24 h or 1 year. Cytotoxicity of the solvents was evaluated in 3T3/NIH mouse fibroblasts using a colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay after exposure for 24 h. No significant differences were detected among solvents after storage for 24 h, except for the water-based group, which showed the lowest μTBS values. After storage for 1 year, the THF-based adhesive system resulted in more stable bonds. Yet, THF showed an intermediate cytotoxicity when compared with the other solvents, being less toxic than phosphate monomer and similar to 2-hydroxyethyl methacrylate. THF seems to be a suitable solvent for adhesive systems. THF is a promising solvent that can be used to improve dentin bond stability.

  4. Molecular dynamics study on the nucleation of methane + tetrahydrofuran mixed guest hydrate.

    Science.gov (United States)

    Wu, Jyun-Yi; Chen, Li-Jen; Chen, Yan-Ping; Lin, Shiang-Tai

    2016-04-21

    The nucleation of methane (CH4), tetrahydrofuran (THF), and CH4 + THF hydrates are investigated by microsecond MD simulations. These three systems exhibit distinct structural developments in the aqueous phase quantified by the formation of cage structures of hydrogen bonded water molecules. The development of a cluster of cages in the CH4 system is limited by the scarce CH4 molecules in the solution, while in the THF system it is limited by the short lifetime of cages. In the CH4 + THF mixed guest system, a small cluster of caged CH4 molecules can be rapidly stabilized by abundant neighboring cages of THF molecules. Therefore, the induction time of the CH4 + THF mixed guest system is found to be significantly shorter than that of the pure CH4 and pure THF systems. Furthermore, the structure of cages found in the initially formed cage clusters are often different from the typical 5(12)6(n) (n = 0, 2, 3, 4) cages observed in clathrate hydrate systems. The cluster of cages may grow or transform into structure I or II clathrate hydrate in the later stages.

  5. Observations related to tetrahydrofuran and methane hydrates for laboratory studies of hydrate-bearing sediments

    Science.gov (United States)

    Lee, J.Y.; Yun, T.S.; Santamarina, J.C.; Ruppel, C.

    2007-01-01

    The interaction among water molecules, guest gas molecules, salts, and mineral particles determines the nucleation and growth behavior of gas hydrates in natural sediments. Hydrate of tetrahydrofuran (THF) has long been used for laboratory studies of gas hydrate-bearing sediments to provide close control on hydrate concentrations and to overcome the long formation history of methane hydrate from aqueous phase methane in sediments. Yet differences in the polarizability of THF (polar molecule) compared to methane (nonpolar molecule) raise questions about the suitability of THF as a proxy for methane in the study of hydrate-bearing sediments. From existing data and simple macroscale experiments, we show that despite its polar nature, THF's large molecular size results in low permittivity, prevents it from dissolving precipitated salts, and hinders the solvation of ions on dry mineral surfaces. In addition, the interfacial tension between water and THF hydrate is similar to that between water and methane hydrate. The processes that researchers choose for forming hydrate in sediments in laboratory settings (e.g., from gas, liquid, or ice) and the pore-scale distribution of the hydrate that is produced by each of these processes likely have a more pronounced effect on the measured macroscale properties of hydrate-bearing sediments than do differences between THF and methane hydrates themselves.

  6. Successful bioaugmentation of an activated sludge reactor with Rhodococcus sp. YYL for efficient tetrahydrofuran degradation.

    Science.gov (United States)

    Yao, Yanlai; Lu, Zhenmei; Zhu, Fengxiang; Min, Hang; Bian, Caimiao

    2013-10-15

    The exchange of tetrahydrofuran (THF)-containing wastewater should significantly affect the performance of an activated sludge system. In this study, the feasibility of using THF-degrading Rhodococcus sp. strain YYL to bioaugment an activated sludge system treating THF wastewater was explored. As indicated by a DGGE analysis, strain YYL alone could not dominate the system, with the concentration of mixed liquor suspended solids (MLSS) decreasing to nearly half of the initial concentration after 45 d, and the microbial diversity was found to be significantly reduced. However, after the reactor was augmented with the mixed culture of strain YYL and two bacilli initially coexisting in the enriched isolation source, strain YYL quickly became dominant in the system and was incorporated into the activated sludge. The concentration of MLSS increased from 2.1g/L to 7.3g/L in 20 d, and the efficiency of THF removal from the system was remarkably improved. After the successful bioaugmentation, more than 95% of THF was completely removed from the wastewater when 20mM THF was continuously loaded into the system. In conclusion, our research first demonstrates that bioaugmentation of activated sludge system for THF degradation is feasible but that successful bioaugmentation should utilize a THF-degrading mixed culture as the inoculum, in which the two bacilli might help strain YYL colonize in activated sludge by co-aggregation. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. A Tetrahydrofuran-selective Optical Solvent Sensor Based on Solvatochromic Polydiacetylene

    Energy Technology Data Exchange (ETDEWEB)

    Park, Dong-Hoon; Kim, Bubsung; Kim, Jong-Man [Hanyang University, Seoul (Korea, Republic of)

    2016-06-15

    Polydiacetylene (PDAs) have received great attention as colorimetric sensors since these conjugated polymers undergo a blue-to-red color change upon various chemical/biochemical and physical stimuli. PDAs have been reported to display thermochromism (heat), solvatochromism (solvent), mechanochromism (mechanical strain) as well as magnetochromism (magnetic force) electrochromism (electric current), and affinochromism (ligand-receptor interaction). The solvent induced color change of PDA is generally non-specific and irreversible. For instance, the PDA derived from 10,12-pentacosadiynoic acid (PCDA) undergoes a blue-to-red (or purple) color change upon exposure to many common organic solvents including tetrahydrofuran (THF), chloroform, dichloromethane, acetone, methanol (MeOH), ethyl acetate (EA), and diethyl ether. The results obtained from Raman spectral analysis suggests that exposure to THF causes the distortion of the backbone of the polymer main chain and some conformational changes in the aliphatic side chain. Solvatochromism of a PDA is closely related to the solubility of a diacetylene monomer. PDA undergoes a color change when the dissolution of unpolymerized monomers causes some void in the PDA supramolecules. Since PCDA-mBzA has a good solubility only in THF, colorimetric transition of PDA occurs only in response to THF. Since solubility of a diacetylene monomer can be manipulated by structural change of the monomer, we believe the strategy described in current investigation should be useful for the development of solvent-specific PDA sensor systems.

  8. Polycondensation of Tetrahydrofuran with Phthalic Anhydride Induced By a Proton Exchanged Montmorillonite Clay

    Directory of Open Access Journals (Sweden)

    Mohammed Belbachir

    2003-05-01

    Full Text Available Abstract: “Maghnite” a montmorillonite sheet silicate clay, exchanged with protons to produce “H-Maghnite” is an efficient catalyst for polymerization of many vinylic and heterocyclic monomers (Belbachir, M. U.S. Patent. 066969.0101 –2001. The structure compositions of both “Maghnite” and “H-Maghnite” have been developed. This catalyst was used for the polycondensation of the tetrahydrofuran with phthalic anhydride. The polymerization was performed under suitable conditions at temperature (40°C, in presence of acetic anhydride. Experiments revealed that polymerization induced by “H-Maghnite”, proceed in bulk and the conversion increases with increasing “H-Maghnite” proportion.

  9. Pervaporation study for the dehydration of tetrahydrofuran-water mixtures by polymeric and ceramic membranes.

    Science.gov (United States)

    McGinness, Colleen A; Slater, C Stewart; Savelski, Mariano J

    2008-12-01

    Pervaporation technology can effectively separate a tetrahydrofuran (THF) solvent-water waste stream at an azeotropic concentration. The performance of a Sulzer 2210 polyvinyl alcohol (PVA) membrane and a Pervatech BV silica membrane were studied, as the operating variables feed temperature and permeate pressure, were varied. The silica membrane was found to exhibit a flux of almost double that of the PVA membrane, but both membranes had comparable separation ability in purifying the solvent-water mixture. At benchmark feed conditions of 96 wt% THF and 4 wt% water, 50 degrees C and 10 torr permeate pressure, the silica membrane flux was 0.276 kg/m(2)hr and selectivity was 365. For both membranes, flux was found to increase at an exponential rate as the feed temperature increased from 20 to 60 degrees C. The flux through the silica membrane increases at a 6% faster rate than the PVA membrane. Flux decreased as permeate pressure was increased from 5 to 25 torr for both membranes. The amount of water in the permeate decreased exponentially as the permeate pressure was increased, but increased linearly with increasing temperature. Optimum conditions for flux and selectivity are at low permeate pressure and high feed temperature. When a small amount of salt is added to the feed solution, an increase in flux is observed. Overall models for flux and permeate concentration were created from the experimental data. The models were used to predict scale-up performance in separating an azeotropic feed waste to produce dehydrated THF solvent for reuse and a permeate stream with a dilute THF concentration.

  10. Gradient HPLC separation of dehydroepiandrosterone (DHEA) from its metabolites and biological congeners: role of tetrahydrofuran in the chromatographic mechanism.

    Science.gov (United States)

    Gergely, András; Horváth, Péter; Szász, György; Veress, Gábor

    2009-08-01

    A three-step gradient reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the separation of dehydroepiandrosterone (DHEA), its sulfate ester (DHEA-S), its three C7-oxidized metabolites (7alphaOH-DHEA, 7betaOH-DHEA, 7-keto-DHEA), and its biosynthetic congeners (androstenedione, testosterone, estradiol, pregnenolone). This new method allows the quantitative characterization of DHEA metabolism and biosynthetic transformation under given physiological, pathological, or therapeutically influenced circumstances. Tetrahydrofuran probably acts as a proton acceptor coadsorbent, while isopropanol behaves as a proton donor during the separation of testosterone, estradiol, and the stereoisomers of 7-OH-DHEA.

  11. Short-chain grafting of tetrahydrofuran and 1,4-dioxane cycles on vinylchloride-maleic anhydride copolymer

    Directory of Open Access Journals (Sweden)

    2009-01-01

    Full Text Available Mass increase of vinylchloride-maleic anhydride (VC-MA copolymer samples aged in tetrahydrofuran (THF or in 1,4-dioxane results from chemical interaction of VC-MA macromolecules with 1,4-dioxane or THF. Microstructure of the products of such modification was proved by infrared spectroscopy (IR- and nuclear magnetic resonance spectroscopy (13C NMR and 1H NMR. Mechanism of modification has been proposed. The results of microstructure research of VC-MA samples aged in THF and in 1,4-dioxane coincide with already known data on the reactions of opening of these and other oxygen-containing cycles under mild conditions.

  12. Measuring and modelling of the combined thermodynamic promoting effect of tetrahydrofuran and cyclopentane on carbon dioxide hydrates

    DEFF Research Database (Denmark)

    Herslund, Peter Jørgensen; Daraboina, Nagu; Thomsen, Kaj

    2014-01-01

    promoters due to its significant pressure reducing effect in hydrate forming systems such as those related to carbon dioxide capture.The present work shows that hydrate dissociation pressures may be lowered by up to 22% compared to those of the cyclopentane promoted carbon dioxide hydrate system by addition......This work documents both experimental data, and by thermodynamic modelling, the synergistic effect occurring in promoted carbon dioxide hydrate systems at the simultaneous presence of tetrahydrofuran and cyclopentane.Cyclopentane has previously been considered a reference among gas hydrate...

  13. Acoustical studies of some derivatives of 1,5-benzodiazepines formamide and tetrahydrofuran solutions at 298.15 K

    Science.gov (United States)

    Baluja, S.; Movaliya, J.; Godvani, N.

    2009-12-01

    Some derivatives of 1,5-benzodiazepines have been synthesized and characterized by TLC, IR, NMR, and Mass Spectral data. The ultrasonic velocity, density and viscosity of these synthesized compounds have been measured in dimethyl formamide and tetrahydrofuran at 298.15 K. From these experimental data, various acoustical parameters such as isentropic compressibility, intermolecular free path length, molar compressibility, Rao’s molar sound function, relaxation strength, internal pressure, free volume etc., have been calculated which helps in understanding the molecular interactions occurring in these solutions.

  14. Regenerative γ-Lactone Annulations: A Modular, Iterative Approach to Oligo-tetrahydrofuran Molecular Stairs and Related Frameworks.

    Science.gov (United States)

    Rashid, Showkat; Bhat, Bilal A; Mehta, Goverdhan

    2015-07-17

    A unified, stereocontrolled, regenerative γ-butyrolactone annulation approach has been conceptualized and validated through syntheses of a range of oligo-THFs. The new protocol is short (four steps), simple (table-top reagents), and efficient (50-61% overall yields). Although the scope of this approach is unlimited, it has been demonstrated up to five iterations on commercial γ-butyrolactone to assemble six fused tetrahydrofuran moieties in a staircase-like architecture. A selection of exploratory transformations is presented to exemplify the potential applications of this protocol.

  15. The effect of stirring on the heterogeneous nucleation of water and of clathrates of tetrahydrofuran/water mixtures

    Directory of Open Access Journals (Sweden)

    P.W. Wilson

    2016-03-01

    Full Text Available The statistics of liquid-to-crystal nucleation are measured for both water and for clathrate-forming mixtures of tetrahydrofuran (THF and water using an automatic lag time apparatus (ALTA. We measure the nucleation temperature using this apparatus in which a single sample is repeatedly cooled, nucleated and thawed. The effect of stirring on nucleation has been evaluated numerically and is discussed. We find that stirring of the solution makes no difference to the nucleation temperature of a given solution in a given tube.

  16. On interfacial properties of tetrahydrofuran: Atomistic and coarse-grained models from molecular dynamics simulation

    Science.gov (United States)

    Garrido, J. M.; Algaba, J.; Míguez, J. M.; Mendiboure, B.; Moreno-Ventas Bravo, A. I.; Piñeiro, M. M.; Blas, F. J.

    2016-04-01

    We have determined the interfacial properties of tetrahydrofuran (THF) from direct simulation of the vapor-liquid interface. The molecules are modeled using six different molecular models, three of them based on the united-atom approach and the other three based on a coarse-grained (CG) approach. In the first case, THF is modeled using the transferable parameters potential functions approach proposed by Chandrasekhar and Jorgensen [J. Chem. Phys. 77, 5073 (1982)] and a new parametrization of the TraPPE force fields for cyclic alkanes and ethers [S. J. Keasler et al., J. Phys. Chem. B 115, 11234 (2012)]. In both cases, dispersive and coulombic intermolecular interactions are explicitly taken into account. In the second case, THF is modeled as a single sphere, a diatomic molecule, and a ring formed from three Mie monomers according to the SAFT-γ Mie top-down approach [V. Papaioannou et al., J. Chem. Phys. 140, 054107 (2014)]. Simulations were performed in the molecular dynamics canonical ensemble and the vapor-liquid surface tension is evaluated from the normal and tangential components of the pressure tensor along the simulation box. In addition to the surface tension, we have also obtained density profiles, coexistence densities, critical temperature, density, and pressure, and interfacial thickness as functions of temperature, paying special attention to the comparison between the estimations obtained from different models and literature experimental data. The simulation results obtained from the three CG models as described by the SAFT-γ Mie approach are able to predict accurately the vapor-liquid phase envelope of THF, in excellent agreement with estimations obtained from TraPPE model and experimental data in the whole range of coexistence. However, Chandrasekhar and Jorgensen model presents significant deviations from experimental results. We also compare the predictions for surface tension as obtained from simulation results for all the models with

  17. Measurement and correlation of isobaric vapor-liquid equilibrium for the binary system of cyclopentane and tetrahydrofuran

    Directory of Open Access Journals (Sweden)

    Yumei Li

    2014-09-01

    Full Text Available Isobaric vapor-liquid equilibrium (VLE data for the cyclopentane and tetrahydrofuran (THF system were measured at 101.3 kPa by using an equilibrium still. Thermodynamic consistency of the experimental data was confirmed by means of the Herington method. The experimental data were correlated and calculated by the Margules, Van Laar and Wilson activity-coefficient models, respectively. The Wilson and Van Laar activity-coefficient models are better than the Margules activity-coefficient model based on the average absolute deviations of temperature and the vapor-phase composition. For the Wilson and Van Laar activity-coefficient models the average absolute deviations between the experimental and the calculated values were 0.24 K and 0.23 K for the boiling point, and 0.0040 for vapor-phase composition, respectively. These agree well with the experimental data. Therefore, it was shown that the Wilson and Van Laar activity-coefficient models satisfactorily correlate the experimental results of the cyclopentane and tetrahydrofuran system.

  18. Kinetic of formation for single carbon dioxide and mixed carbon dioxide and tetrahydrofuran hydrates in water and sodium chloride aqueous solution

    NARCIS (Netherlands)

    Sabil, K.M.; Duarte, A.R.C.; Zevenbergen, J.F.; Ahmad, M.M.; Yusup, S.; Omar, A.A.; Peters, C.J.

    2010-01-01

    A laboratory-scale reactor system is built and operated to measure the kinetic of formation for single and mixed carbon dioxide-tetrahydrofuran hydrates. The T-cycle method, which is used to collect the kinetic data, is briefly discussed. For single carbon dioxide hydrate, the induction time

  19. Water dissociation in a radio-frequency electromagnetic field with ex situ electrodes—decomposition of perfluorooctanoic acid and tetrahydrofuran

    Science.gov (United States)

    Schneider, Jens; Holzer, Frank; Kraus, Markus; Kopinke, Frank-Dieter; Roland, Ulf

    2016-10-01

    The application of radio waves with a frequency of 13.56 MHz on electrolyte solutions in a capillary reactor led to the formation of reactive hydrogen and oxygen species and finally to molecular oxygen and hydrogen. This process of water splitting can be principally used for the elimination of hazardous chemicals in water. Two compounds, namely perfluorooctanoic acid (PFOA) and tetrahydrofuran, were converted using this process. Their main decomposition products were highly volatile and therefore transferred to a gas phase, where they could be identified by GC-MS analyses. It is remarkable that the chemical reactions could benefit from both the oxidizing and reducing species formed in the plasma process, which takes place in gas bubbles saturated with water vapor. The breaking of C-C and C-F bonds was proven in the case of PFOA, probably initiated by electron impacts and radical reactions.

  20. An Unusual Tetrahydrofuran Lignan from the Roots of Zanthoxylum planispinum and the Potential Anti-inflammatory Effects.

    Science.gov (United States)

    Su, Guang-Yao; Cheng, Yu-Chun; Wang, Kui-Wu; Wang, Xiang-Yang; Wu, Bin

    2017-01-01

    An unusual tetrahydrofuran lignin, zanthplanispine (1), together with 14 known lignans (2 - 15) were isolated from the AcOEt-soluble fraction from the MeOH extract of Z. planispinum roots. The structures of 1 was elucidated on the basis of 1D- and 2D-NMR experiments as well as HR-ESI-MS analysis. The known compounds were identified by the comparison of their NMR data with previously reported in the literatures. Bioassay showed that compounds 1 - 4 could inhibit nitric oxide (NO) production in lipopolysaccharide (LPS) stimulated RAW 264.7 cells. In particular, compound 1 showed significant inhibitory activity with an IC 50 value of 36.8 μm. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

  1. Absolute cross sections for electronic excitation of condensed tetrahydrofuran (THF) by 11-16 eV electrons.

    Science.gov (United States)

    Lemelin, V; Bass, A D; Cloutier, P; Sanche, L

    2016-11-07

    Absolute cross section (CS) data on the interaction of low energy electrons with DNA and its molecular constituents are required as input parameters in Monte-Carlo type simulations, for several radiobiological applications. Previously [V. Lemelin et al., J. Chem. Phys. 144, 074701 (2016)], we measured absolute vibrational CSs for low-energy electron scattering from condensed tetrahydrofuran, a convenient surrogate for the deoxyribose. Here we report absolute electronic CSs for energy losses of between 6 and 11.5 eV, by electrons with energies between 11 and 16 eV. The variation of these CSs with incident electron energy shows no evidence of transient anion states, consistent with theoretical and other experimental results, indicating that initial electron capture leading to DNA strand breaks occurs primarily on DNA bases or the phosphate group.

  2. Water-tunable solvatochromic and nanoaggregate fluorescence: dual colour visualisation and quantification of trace water in tetrahydrofuran.

    Science.gov (United States)

    Tanioka, Masaru; Kamino, Shinichiro; Muranaka, Atsuya; Shirasaki, Yoshinao; Ooyama, Yousuke; Ueda, Masashi; Uchiyama, Masanobu; Enomoto, Shuichi; Sawada, Daisuke

    2017-01-04

    While investigating the unique optical properties of aminobenzopyranoxanthenes (ABPXs), organic fluorescent dyes with the fusion of two rhodamines, we have found that the spirolactone form of ABPXs exhibited solvatochromic fluorescence in organic solvents. Detailed spectrophotometric and theoretical analyses showed that the solvatochromic fluorescence of ABPXs originated from the photo-excited charge separation in solvents of different dipolarities. Further studies revealed that fluorescent nanoaggregates were also formed in highly concentrated solution. The intriguing dual fluorescence properties of ABPXs were tunable in response to the water content, and served as a new detection principle for naked-eye visualisation (above 0.5 wt%) and quantification (0.010-0.125 wt%) of water in tetrahydrofuran.

  3. Design and synthesis of potent HIV-1 protease inhibitors with (S)-tetrahydrofuran-tertiary amine-acetamide as P2-ligand: Structure-activity studies and biological evaluation.

    Science.gov (United States)

    Bai, Xiaoguang; Yang, Zhiheng; Zhu, Mei; Dong, Biao; Zhou, Lei; Zhang, Guoning; Wang, Juxian; Wang, Yucheng

    2017-09-08

    The design, synthesis, and SAR study of a new series of HIV-1 protease inhibitors incorporating stereochemically defined tetrahydrofuran-tertiary amine-acetamide P2-ligand are described. Various substituent effects on the tertiary amine P2-ligand and phenylsulfonamide P2'-ligand were investigated to maximize the ligand-binding site interactions in the protease active site. Most of inhibitors displayed low nanomolar to subnanomolar inhibitory potency. Inhibitor 20e containing N-(S-tetrahydrofuran)-N-(2-methoxyethyl)acetamide as P2-ligand along with 4-methoxylphenylsulfonamide as P2'-ligand displayed the most potent enzyme inhibitory activity (IC50 = 0.35 nM) and remarkably low cytotoxicity (CC50 = 305 μM). Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  4. Organic Liquids-Responsive β-Cyclodextrin-Functionalized Graphene-Based Fluorescence Probe: Label-Free Selective Detection of Tetrahydrofuran

    Directory of Open Access Journals (Sweden)

    Huawen Hu

    2014-06-01

    Full Text Available In this study, a label-free graphene-based fluorescence probe used for detection of volatile organic liquids was fabricated by a simple, efficient and low-cost method. To fabricate the probe, a bio-based β-cyclodextrin (β-CD was firstly grafted on reduced graphene surfaces effectively and uniformly, as evidenced by various characterization techniques such as Ultraviolet/Visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The subsequent inclusion of Rhodamine B (RhB into the inner cavities of the β-CD grafted on the graphene surfaces was achieved easily by a solution mixing method, which yielded the graphene-based fluorescent switch-on probe. In addition, the gradual and controllable quenching of RhB by Fluorescence Resonance Energy Transfer from RhB to graphene during the process of stepwise accommodation of the RhB molecules into the β-CD-functionalized graphene was investigated in depth. A wide range of organic solvents was examined using the as-fabricated fluorescence probe, which revealed the highest sensitivity to tetrahydrofuran with the detection limit of about 1.7 μg/mL. Some insight into the mechanism of the different responsive behaviors of the fluorescence sensor to the examined targets was also described.

  5. A newly isolated strain capable of effectively degrading tetrahydrofuran and its performance in a continuous flow system.

    Science.gov (United States)

    Chen, Jian-Meng; Zhou, Yu-Yang; Chen, Dong-Zhi; Jin, Xiao-Jun

    2010-08-01

    A Gram-negative strain DT4, capable of growing aerobically on tetrahydrofuran (THF) as the sole carbon and energy source was isolated from a pharmaceutical wastewater treatment plant. It was identified as Pseudomonas oleovorans by morphological and physiological characteristics as well as Biolog profiling and 16S rDNA sequence. Cells of P. oleovorans DT4 pre-cultured in THF could degrade 5 mM THF completely without lag phase. The generation time of 2.7 h and the maximum degradation rate of 203.9 mg THF/(h g dry weight) were observed, demonstrating that DT4 bears the highest THF-degrading activity in ever described strains. Furthermore, THF concentration as high as 100 mM was tolerated by the culture. Several important compounds including gamma-butyrrolactone and benzene could be directly metabolized, whereas other pollutants (e.g., tetrahydropyrane) could be cometabolized by DT4. THF removal was achieved in a continuous flow system with the maximum specific growth rate 0.113 h(-1) and half-saturation constant 1.224 mg/L, indicating the great potential of THF bioremediation in future full-scale application. Copyright 2010 Elsevier Ltd. All rights reserved.

  6. Dielectric relaxation of binary mixtures of tetrahydrofuran and N-methylformamide in benzene solution using microwave absorption studies

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Raman [Govt. Coll. Amb. (H.P.) (India); Kumar, Raman [L. R. Inst. of Engineering and Tech., Solan (H.P.) (India); Rangra, Vir S. [Physics Dept., Himachal Pradesh Univ., Shimla (H.P.) (India)

    2010-01-15

    Using standard standing wave microwave X-band technique and following Gopala Krishna's single frequency (9.90 GHz) concentration variational method, the dielectric relaxation times {tau} and the dipole moments {mu} of dilute solutions of Tetrahydrofuran (THF), N-methylformamide (NMF), and THF+NMF binary mixtures in benzene solutions have been calculated at different temperatures (25 C, 30 C, 35 C, and 40 C). The energy parameters ({delta}H{sub {epsilon}}, {delta}F{sub {epsilon}}, {delta}S{sub {epsilon}}) for the dielectric relaxation process for the THF+NMF binary mixture containing 30 mol% THF have been calculated at 25 C, 30 C, 35 C, and 40 C and compared with the corresponding viscosity parameters. A good agreement between the free energy of activation from these two sets of values shows that the dielectric relaxation process like the viscous flow process can be treated as a rate process. From relaxation time behaviour of THF and NMF binary mixture in benzene solution, solute-solute types of the molecular association has been proposed. (orig.)

  7. Non-hydrolytic formation of silica and polysilsesquioxane particles from alkoxysilane monomers with formic acid in toluene/tetrahydrofuran solutions

    Science.gov (United States)

    Boday, Dylan J.; Tolbert, Stephanie; Keller, Michael W.; Li, Zhe; Wertz, Jason T.; Muriithi, Beatrice; Loy, Douglas A.

    2014-03-01

    Silica and polysilsesquioxane particles are used as fillers in composites, catalyst supports, chromatographic separations media, and even as additives to cosmetics. The particles are generally prepared by hydrolysis and condensation of tetraalkoxysilanes and/or organotrialkoxysilanes, respectively, in aqueous alcohol solutions. In this study, we have discovered a new, non-aqueous approach to prepare silica and polysilsesquioxane particles. Spherical, nearly monodisperse, silica particles (600-6,000 nm) were prepared from the reaction of tetramethoxysilane with formic acid (4-8 equivalents) in toluene or toluene/tetrahydrofuran solutions. Polymerization of organotrialkoxysilanes with formic acid failed to afford particles, but bridged polysilsesquioxane particles were obtained from monomers with two trialkoxysilyl group attached to an organic-bridging group. The mild acidic conditions allowed particles to be prepared from monomers, such as bis(3-triethoxysilylpropyl)tetrasulfide, which are unstable to Stöber or base-catalyzed emulsion polymerization conditions. The bridged polysilsesquioxane particles were generally less spherical and more polydisperse than silica particles. Both silica and bridged polysilsesquioxane nanoparticles could be prepared in good yields at monomer concentrations considerably higher than used in Stöber or emulsion approaches.

  8. Poly(ethylene glycol-poly(tetrahydrofuran-poly(ethylene glycol triblock copolymer : Synthesis, crystallization behavior and novel morphology

    Directory of Open Access Journals (Sweden)

    X. Q. Liao

    2013-05-01

    Full Text Available Poly(ethylene glycol-poly(tetrahydrofuran-poly(ethylene glycol (PEG-PTHF-PEG triblock copolymer was synthesized by ring-opening polymerization of ethylene oxide using sodium alcoholate of PTHF as the macroinitiator. Its crystallization behavior and formation mechanisms of different crystal structures were studied. The study showed that the molecular weight of PEG-PTHF-PEG exhibited a significant effect on its crystallization: that is, with the increase of the copolymer’s molecular weight, the crystallizability of PTHF blocks decreased gradually, which led to the transition of copolymer from crystalline-crystalline to crystalline-amorphous. By adjusting the total molecular weight of triblock copolymer, the crystallization process can be effectively controlled, and as a result, different spherulite structures were obtained. Particularly, when PTHF blocks became amorphous, novel double concentric spherulites were observed. The morphological structures were studied by differential scanning calorimetry (DSC, Fourier transform infrared spectroscopy (FTIR, scanning electron microscope (SEM, polarized optical microscopy (POM, and its crystalline process was investigated.

  9. Dimethyl 3,3′-diphenyl-2,2′-[(S-thiophene-2,5-diylbis(carbonylazanediyl]dipropanoate tetrahydrofuran monosolvate

    Directory of Open Access Journals (Sweden)

    GuoXin Sun

    2010-10-01

    Full Text Available The title compound, C26H26N2O6S·C4H8O, a solvated bis-amide derivative, is also a chiral amino acid ester with l-phenylalanine methyl ester groups as amine substituents. The thiophene-2,5-dicarboxamide core approximates C2 point symmetry. The tetrahydrofuran solvent molecule is linked to the main molecule through an intermolecular N—H...O hydrogen bond. The central ring makes dihedral angles of 90.0 (2 and 76.5 (2° with the pendant rings.

  10. Tetrahydrofuran-water extraction, in-line clean-up and selective liquid chromatography/tandem mass spectrometry for the quantitation of perfluorinated compounds in food at the low picogram per gram level

    NARCIS (Netherlands)

    Ballesteros-Gómez, A.; Rubio, S.; van Leeuwen, S.P.J.

    2010-01-01

    A new solvent extraction system was developed for extraction of PFCs from food. The extraction is carried out with 75:25 (v/v) tetrahydrofuran:water, a solvent mixture that provides an appropriate balance of hydrogen bonding, dispersion and dipole-dipole interactions to efficiently extract PFCs with

  11. {μ-1,2-Bis[bis(4-methoxyphenylphosphanyl]-1,2-diethylhydrazine-κ2P:P′}bis[chloridogold(I] tetrahydrofuran disolvate

    Directory of Open Access Journals (Sweden)

    Judy Coates

    2011-10-01

    Full Text Available The title compound, [Au2Cl2(C32H38N2O4P2]·2C4H8O, is formed from a bidentate phosphine ligand complexed to two linear gold(I nuclei [P—Au—Cl = 175.98 (3°]. The nuclei are 3.1414 (2 Å apart. The molecule exhibits a twofold symmetry axis. Stacks of the compound are formed through intermolecular C—H...Cl interactions, while the tetrahydrofuran (THF solvate is further attached to the stacks through weak C—H...O hydrogen bonding from the THF O atom to two separate H atoms on the complex.

  12. Properties of Electrospun Nanofibers of Multi-Block Copolymers of [Poly-ε-caprolactone-b-poly(tetrahydrofuran-co-ε-caprolactone]m Synthesized by Janus Polymerization

    Directory of Open Access Journals (Sweden)

    Muhammad Ijaz Shah

    2017-10-01

    Full Text Available Novel biodegradable multiblock copolymers of [PCL-b-P(THF-co-CL]m with PCL fractions of 53.3 and 88.4 wt % were prepared by Janus polymerization of ε-caprolactone (CL and tetrahydrofuran (THF. Their electrospun mats were obtained with optimized parameters containing bead-free nanofibers whose diameters were between 290 and 520 nm. The mechanical properties of the nanofiber scaffolds were measured showing the tensile strength and strain at break of 8–10 MPa and 123–161%, respectively. Annealing improved their mechanical properties and their tensile strength and strain at break of the samples increased to 10–13 MPa and 267–338%, respectively. Due to the porous structure and crystallization in nanoscale confinement, the mechanical properties of the nanofiber scaffolds appeared as plastics, rather than as the elastomers observed in bulk thermal-molded film.

  13. Effect tetrahydrofuran as solvent in the synthesis of mullite by the Pechini; Efeito do tetrahidrofurano como solvente na sintese de mulita pelo Metodo Pechini

    Energy Technology Data Exchange (ETDEWEB)

    Braga, A.N.S.; Santos, V.B. [Universidade Federal do Piaui (UFPI), Teresina, PI (Brazil); Simoes, V.N.; Neves, G.A.; Lira, H.L.; Menezes, R.R., E-mail: Aluskasimoes@homail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

    2016-07-01

    Mullite has been considered interesting in recent decades, due to its properties. The reaction mechanisms in the mullite formation may vary according to the precursor and the methods employed. In order to get mullite by a promising chemical synthesis and understudied in its production, this paper aims to synthesize mullite by Pechini method. We investigated the mullite crystallization kinetics from use of tetrahydrofuran as solvent. The samples were characterized by diffraction of X-ray (XRD), thermal analysis and scanning electron microscopy (SEM). The XRD results showed the formation of mullite, but together with the alpha alumina phase. Thermal analysis confirmed the disruption of the polymer chain prior to the formation of crystalline phases, with a total weight loss of 97%. The SEM showed a morphology consists of large aggregates, damaging the properties of refractory and performance of the material. (author)

  14. Application of the cubic-plus-association (CPA) equation of state to model the fluid phase behaviour of binary mixtures of water and tetrahydrofuran

    DEFF Research Database (Denmark)

    Herslund, Peter Jørgensen; Thomsen, Kaj; Abildskov, Jens

    2013-01-01

    The complex fluid phase behaviour, of the binary system comprised of water and tetrahydrofuran (THF) is modelled by use of the cubic-plus-association (CPA) equation of state. A total of seven modelling approaches are analysed, differing only in their way of describing THF and its interactions...... presented in this work, it is suggested to model this binary system considering THF as cross-associating only, with two cross-association sites. The use of a temperature dependent binary interaction parameter and a correlated binary cross-association volume then allows for both accurate VLE and LLE...... (hydrogen bonding) with water.The qualitative behaviour of the fluid phase equilibria in this system can only be described by CPA when cross-association between water and THF is allowed.Six of the seven tested modelling scenarios allow for cross-association between the two compounds. These scenarios...

  15. International Conference on Harmonisation; final recommendations on the revision of the permitted daily exposures for two solvents, n-methylpyrrolidone and tetrahydrofuran, according to the maintenance procedures for the guidance Q3C Impurities: Residual Solvents; Availability. Notice.

    Science.gov (United States)

    2003-11-13

    The Food and Drug Administration (FDA) is announcing final recommendations to revise the permitted daily exposures (PDEs) for two solvents, n-methylpyrrolidone (NMP) and tetrahydrofuran (THF), according to the maintenance procedures for the guidance for industry entitled "Q3C Impurities: Residual Solvents." The final recommendations were reached under the auspices of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH).

  16. Analytical validation applied to simultaneous determination of solvents dichloromethane (DCM), methyl isobutyl ketone (MIBK), tetrahydrofuran (THF) and toluene (TOL) in urine by headspace extraction and injection on chromatographic system with a flame ionization detector

    Science.gov (United States)

    Muna, E. D. M.; Pereira, R. P.

    2016-07-01

    The determination of the volatile organic solvents dichloromethane (DCM), methyl isobutyl ketone (MIBK), tetrahydrofuran (THF) and toluene (TOL) is applied on toxicological monitoring of employees in various industrial activities. The gas chromatography technique with flame ionization detector and headspace injection system has been applied. The analytical procedure developed allows the simultaneous determination of the above-mentioned solvents and the accuracy of the method was tested following the INMETRO guidelines through the DOQ-CGRE 008 Rev.04-July/2011.

  17. Biodegradation of tetrahydrofuran by Pseudomonas oleovorans DT4 immobilized in calcium alginate beads impregnated with activated carbon fiber: mass transfer effect and continuous treatment.

    Science.gov (United States)

    Chen, Dong-Zhi; Fang, Jun-Yi; Shao, Qian; Ye, Jie-Xu; Ouyang, Du-Juan; Chen, Jian-Meng

    2013-07-01

    A novel entrapment matrix, calcium alginate (CA) coupled with activated carbon fiber (ACF), was prepared to immobilize Pseudomonas oleovorans DT4 for degrading tetrahydrofuran (THF). The addition of 1.5% ACF increased the adsorption capacity of the immobilized bead, thus resulting in an enhanced average removal rate of 30.3mg/(Lh). The synergism between adsorption and biodegradation was observed in the hybrid CA-ACF beads instead of in the system comprising CA beads and freely suspended ACF. The effective diffusion coefficient of the CA-ACF bead was not significantly affected by bead size, but the bead's value of 1.14×10(-6)cm(2)/s (for the bead diameter of 0.4 cm) was larger than that of the CA bead by almost one order of magnitude based on the intraparticle diffusion-reaction kinetics analysis. Continuous treatment of the THF-containing wastewater was succeeded by CA-ACF immobilized cells in a packed-bed reactor for 54 d with a >90% removal efficiency. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Continuous hydrogenation of ethyl levulinate to γ-valerolactone and 2-methyl tetrahydrofuran over alumina doped Cu/SiO2 catalyst: the potential of commercialization

    Science.gov (United States)

    Zheng, Junlin; Zhu, Junhua; Xu, Xuan; Wang, Wanmin; Li, Jiwen; Zhao, Yan; Tang, Kangjian; Song, Qi; Qi, Xiaolan; Kong, Dejin; Tang, Yi

    2016-01-01

    Hydrogenation of levulinic acid (LA) and its esters to produce γ-valerolactone (GVL) and 2-methyl tetrahydrofuran (2-MTHF) is a key step for the utilization of cellulose derived LA. Aiming to develop a commercially feasible base metal catalyst for the production of GVL from LA, with satisfactory activity, selectivity, and stability, Al2O3 doped Cu/SiO2 and Cu/SiO2 catalysts were fabricated by co-precipitation routes in parallel. The diverse physio-chemical properties of these two catalysts were characterized by XRD, TEM, dissociative N2O chemisorptions, and Py-IR methods. The catalytic properties of these two catalysts were systematically assessed in the continuous hydrogenation of ethyl levulinate (EL) in a fixed-bed reactor. The effect of acidic property of the SiO2 substrate on the catalytic properties was investigated. To justify the potential of its commercialization, significant attention was paid on the initial activity, proper operation window, by-products control, selectivity, and stability of the catalyst. The effect of reaction conditions, such as temperature and pressure, on the performance of the catalyst was also thoroughly studied. The development of alumina doped Cu/SiO2 catalyst strengthened the value-chain from cellulose to industrially important chemicals via LA and GVL. PMID:27377401

  19. Crystal structure of an unknown tetrahydrofuran solvate of tetrakis(μ3-cyanato-κ3N:N:Ntetrakis[(triphenylphosphane-κPsilver(I

    Directory of Open Access Journals (Sweden)

    Peter Frenzel

    2015-10-01

    Full Text Available In the title compound, [{[(C6H53P]Ag}4{NCO}4], a distorted Ag4N4-heterocubane core is set up by four AgI ions being coordinated by the N atoms of the cyanato anions in a μ3-bridging mode. In addition, a triphenylphosphine ligand is datively bonded to each of the AgI ions. Intramolecular Ag...Ag distances as short as 3.133 (9 Å suggest the presence of argentophilic (d10...d10 interactions. Five moderate-to-weak C—H...O hydrogen-bonding interactions are observed in the crystal structure, spanning a three-dimensional network. A region of electron density was treated with the SQUEEZE procedure in PLATON [Spek (2015. Acta Cryst. C71, 9–18] following unsuccessful attempts to model it as being part of disordered tetrahydrofuran solvent molecules. The given chemical formula and other crystal data do not take into account these solvent molecules.

  20. Moving solvated electrons with light: nonadiabatic mixed quantum/classical molecular dynamics simulations of the relocalization of photoexcited solvated electrons in tetrahydrofuran (THF).

    Science.gov (United States)

    Bedard-Hearn, Michael J; Larsen, Ross E; Schwartz, Benjamin J

    2006-11-21

    Motivated by recent ultrafast spectroscopic experiments [Martini et al., Science 293, 462 (2001)], which suggest that photoexcited solvated electrons in tetrahydrofuran (THF) can relocalize (that is, return to equilibrium in solvent cavities far from where they started), we performed a series of nonequilibrium, nonadiabatic, mixed quantum/classical molecular dynamics simulations that mimic one-photon excitation of the THF-solvated electron. We find that as photoexcited THF-solvated electrons relax to their ground states either by continuous mixing from the excited state or via nonadiabatic transitions, approximately 30% of them relocalize into cavities that can be over 1 nm away from where they originated, in close agreement with the experiments. A detailed investigation shows that the ability of excited THF-solvated electrons to undergo photoinduced relocalization stems from the existence of preexisting cavity traps that are an intrinsic part of the structure of liquid THF. This explains why solvated electrons can undergo photoinduced relocalization in solvents like THF but not in solvents like water, which lack the preexisting traps necessary to stabilize the excited electron in other places in the fluid. We also find that even when they do not ultimately relocalize, photoexcited solvated electrons in THF temporarily visit other sites in the fluid, explaining why the photoexcitation of THF-solvated electrons is so efficient at promoting recombination with nearby scavengers. Overall, our study shows that the defining characteristic of a liquid that permits the photoassisted relocalization of solvated electrons is the existence of nascent cavities that are attractive to an excess electron; we propose that other such liquids can be found from classical computer simulations or neutron diffraction experiments.

  1. Phase equilibria in ternary (carbon dioxide + tetrahydrofuran + water) system in hydrate-forming region: Effects of carbon dioxide concentration and the occurrence of pseudo-retrograde hydrate phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Sabil, Khalik M. [Delft University of Technology, Laboratory of Process Equipment, Mechanical, Maritime and Materials Eng, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Chemical Engineering Programme, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Witkamp, Geert-Jan [Delft University of Technology, Laboratory of Process Equipment, Mechanical, Maritime and Materials Eng, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Peters, Cor J., E-mail: C.J.Peters@tudelft.n [Delft University of Technology, Laboratory of Process Equipment, Mechanical, Maritime and Materials Eng, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Chemical Engineering Programme, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); The Petroleum Institute, Chemical Engineering Program, Bu Hasa Building, Room 2203, P.O. Box 2203, Abu Dhabi (United Arab Emirates)

    2010-01-15

    In the present work, the three- and four-phase hydrate equilibria of (carbon dioxide (CO{sub 2}) + tetrahydrofuran (THF) + water) system are measured by using Cailletet equipment in the temperature and pressure range of (272 to 292) K and (1.0 to 7.5) MPa, respectively, at different CO{sub 2} concentration. Throughout the study, the concentration of THF is kept constant at 5 mol% in the aqueous solution. In addition, the fluid phase transitions of L{sub W}-L{sub V}-V -> L{sub W}-L{sub V} (bubble point) and L{sub W}-L{sub V}-V -> L{sub W}-V (dew point) are determined when they are present in the ternary system. For comparison, the three-phase hydrate equilibria of binary (CO{sub 2} + H{sub 2}O) are also measured. Experimental measurements show that the addition of THF as a hydrate promoter extends hydrate stability region by elevating the hydrate equilibrium temperature at a specified pressure. The three-phase equilibrium line H-L{sub W}-V is found to be independent of the overall concentration of CO{sub 2}. Contradictory, at higher pressure, the phase equilibria of the systems are significantly influenced by the overall concentration of CO{sub 2} in the systems. A liquid-liquid phase split is observed at overall concentration of CO{sub 2} as low as 3 mol% at elevated pressure. The region is bounded by the bubble-points line (L{sub W}-L{sub V}-V -> L{sub W}-L{sub V}), dew points line (L{sub W}-L{sub V}-V -> L{sub W} + V) and the four-phase equilibrium line (H + L{sub W} + L{sub V} + V). At higher overall concentration of CO{sub 2} in the ternary system, experimental measurements show that pseudo-retrograde behaviour exists at pressure between (2.5 and 5) MPa at temperature of 290.8 K.

  2. 8-Iodoquinolinium triiodide tetrahydrofuran solvate

    Directory of Open Access Journals (Sweden)

    Jung-Ho Son

    2008-11-01

    Full Text Available The title compound, C9H7IN+·I3−·C4H8O, was synthesized from 8-aminoquinoline using the Sandmeyer reaction. The 8-iodoquinolinium cation is essentially planar and the triiodide ion is almost linear. N—H...O hydrogen bonds, and intermolecular I...I [3.7100 (5 Å] and I...H interactions, between the cation, anion and solvent molecules result in the formation of sheets oriented parallel to the (overline{1}03 plane. Between the sheets, 8-iodoquinolinium and triiodide ions are stacked alternately, with I...C distances in the range ∼3.8–4.0 Å.

  3. MOLECULAR-STRUCTURE AND CHARGE-DISTRIBUTION OF THE 4F AND 5F ELEMENTS .3. DIPOLE-MOMENTS AND CHARGE-DISTRIBUTION OF 1/1-ADDUCTS OF TRIS(CYCLOPENTADIENYL)LANTHANOIDS(III) AND TRIS(CYCLOPENTADIENYL) ACTINOIDS(III) WITH TETRAHYDROFURAN - X-RAY STRUCTURAL-ANALYSIS OF (C5H5)3DY.THF

    NARCIS (Netherlands)

    MAIER, R; KANELLAKOPULOS, B; APOSTOLIDIS, C; NUBER, B

    1992-01-01

    The dielectricity constant and the dipole moment of the 1:1 adducts of the tris(cyclopentadienyl)compounds of the trivalent lanthanoids La to Lu (with exception of the Pm compound) and of the lighter actinoids Th, U, Np, and Pu with tetrahydrofuran, (C5H5)3M(III).THF, were measured and the charge

  4. Molecular thermodynamic analysis for assessing the relationship between reentrant swelling behavior and ternary liquid-liquid equilibrium for poly(N-isopropylacrylamide) nanometer-sized gel particles in a water-tetrahydrofuran cosolvent system.

    Science.gov (United States)

    Jung, Sang Chul; Bae, Young Chan

    2012-02-23

    The influence of phase separation on swelling behavior was investigated based on the thermodynamic framework of reswelling phenomena. The cloud-point for a ternary system of water(1)-tetrahydrofuran (THF)(2)-poly(N-isopropylacrylamide)(3) was examined by thermo-optical analysis (TOA). Nanometer-sized N-isopropylacrylamide (NIPA) gel particles were prepared by precipitation polymerization, and their swelling behaviors were determined using photon correlation spectroscopy (PCS). NIPA gel particles underwent reswelling when the ratio of water to THF was varied. First, the modified double lattice model (MDL) was employed to determine ternary interaction energy parameters for the liquid-liquid equilibrium (LLE) of linear poly-NIPA in a water-THF cosolvent system. The reentrant swelling equilibria of the NIPA gel in the water-THF system were then calculated using the interaction energy parameters. © 2012 American Chemical Society

  5. Synthesis and 2D-QSAR studies of neolignan-based diaryl-tetrahydrofuran and -furan analogues with remarkable activity against Trypanosoma cruzi and assessment of the trypanothione reductase activity.

    Science.gov (United States)

    Hartmann, Ana Paula; de Carvalho, Marcelo Rodrigues; Bernardes, Lilian Sibelle Campos; Moraes, Milena Hoehr de; de Melo, Eduardo Borges; Lopes, Carla Duque; Steindel, Mario; da Silva, João Santana; Carvalho, Ivone

    2017-11-10

    Two series of diaryl-tetrahydrofuran and -furan were synthesised and screened for anti-trypanosomal activity against trypomastigote and amastigote forms of Trypanosoma cruzi, the causative agent of Chagas disease. Based on evidence that modification of a natural product may result in a more effective drug than the natural product itself, and using known neolignan inhibitors veraguensin 1 and grandisin 2 as templates to synthesise simpler analogues, remarkable anti-trypanosomal activity and selectivity were found for 3,5-dimethoxylated diaryl-furan 5c and 2,4-dimethoxylated diaryl-tetrahydrofuran 4e analogues with EC 50 0.01 μM and EC 50 0.75 μM, respectively, the former being 260-fold more potent than veraguensin 1 and 150-fold better than benznidazole, the current available drugs for Chagas disease treatment. The ability of the most potent anti-trypanosomal compounds to penetrate LLC-MK2 cells infected with T. cruzi amastigotes parasite was tested, which revealed 4e and 5e analogues as the most effective, causing no damage to mammalian cells. In particular, the majority of the derivatives were non-toxic against mice spleen cells. 2D-QSAR studies show the rigid central core and the position of dimethoxy-aryl substituents dramatically affect the anti-trypanosomal activity. The mode of action of the most active anti-trypanosomal derivatives was investigated by exploring the anti-oxidant functions of Trypanothione reductase (TR). As a result, diarylfuran series displayed the strongest inhibition, highlighting compounds 5d-e (IC 50 19.2 and 17.7 μM) and 5f-g (IC 50 8.9 and 7.4 μM), respectively, with similar or 2-fold higher than the reference inhibitor clomipramine (IC 50 15.2 μM). Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  6. Crystal structure of cis-bis[4-phenyl-2-(1,2,3,4-tetrahydronaphthalen-1-ylidenehydrazinecarbothioamidato-κ2N1,S]nickel(II monohydrate tetrahydrofuran disolvate

    Directory of Open Access Journals (Sweden)

    Adriano Bof de Oliveira

    2014-08-01

    Full Text Available The reaction of NiII acetate tetrahydrate with the ligand 4-phenyl-2-(1,2,3,4-tetrahydronaphthalen-1-ylidenehydrazinecarbothioamide in a 2:1 molar ratio yielded the title compound, [Ni(C16H16N3S2]·2C4H8O·H2O. The deprotonated ligands act as N,S-donors, forming five-membered metallacycles with the metal ion exhibiting a cis coordination mode unusual for thiosemicarbazone complexes. The NiII ion is four-coordinated in a tetrahedrally distorted square-planar geometry. Trans-arranged anagostic C—H...Ni interactions are observed. In the crystal, the complex molecules are linked by water molecules through N—H...O and O—H...S hydrogen-bonding interactions into centrosymmetric dimers stacked along the c axis, forming rings of graph-set R44(12. Classical O—H...O hydrogen bonds involving the water and tetrahydrofuran solvent molecules as well as weak C—H...π interactions are also present.

  7. Structure and reactivity of lithium amides. /sup 6/Li, /sup 13/C, and /sup 15/N NMR spectroscopic studies and colligative measurements of lithium diphenylamide and lithium diphenylamide-lithium bromide complex solvated by tetrahydrofuran

    Energy Technology Data Exchange (ETDEWEB)

    DePue, J.S.; Collum, D.B.

    1988-08-03

    /sup 6/Li, /sup 13/C, and /sup 15/N NMR spectroscopic studies of lithium diphenylamide in THF/hydrocarbon solutions (THF = tetrahydrofuran) detected two different species. /sup 6/Li and /sup 15/N NMR spectroscopic studies of (/sup 6/Li, /sup 15/N)lithium diphenylamide showed the species observed at low THF concentrations to be a cyclic oligomer. Structural analogies provided strong support for a dimer while colligative measurements at 0/degrees/C indicated the dimer to be di- or trisolvated. On the basis of the observed mass action effects, the species appearing at intermediate THF concentrations is assigned as a contact or solvent-separated ion-paired monomer. Lithium diphenylamide forms a 1:1 adduct with lithium bromide at low THF concentrations. A combination of /sup 6/Li-/sup 15/N double labeling studies and colligative measurements supports a trisolvated cyclic mixed dimer structure. Although detailed spectroscopic studies at elevated THF concentrations were precluded by high fluctionality, the similarity of the /sup 13/C chemical shifts of lithium diphenylamide in the presence and absence of lithium bromide provide indirect evidence that the mixed dimer undergoes a THF concentration dependent dissociation to the monomeric amide and free lithium bromide. 24 references, 9 figures, 2 tables.

  8. Design of HIV-1 Protease Inhibitors with Amino-bis-tetrahydrofuran Derivatives as P2-Ligands to Enhance Backbone-Binding Interactions: Synthesis, Biological Evaluation, and Protein-Ligand X-ray Studies.

    Science.gov (United States)

    Ghosh, Arun K; Martyr, Cuthbert D; Osswald, Heather L; Sheri, Venkat Reddy; Kassekert, Luke A; Chen, Shujing; Agniswamy, Johnson; Wang, Yuan-Fang; Hayashi, Hironori; Aoki, Manabu; Weber, Irene T; Mitsuya, Hiroaki

    2015-09-10

    Structure-based design, synthesis, and biological evaluation of a series of very potent HIV-1 protease inhibitors are described. In an effort to improve backbone ligand-binding site interactions, we have incorporated basic-amines at the C4 position of the bis-tetrahydrofuran (bis-THF) ring. We speculated that these substituents would make hydrogen bonding interactions in the flap region of HIV-1 protease. Synthesis of these inhibitors was performed diastereoselectively. A number of inhibitors displayed very potent enzyme inhibitory and antiviral activity. Inhibitors 25f, 25i, and 25j were evaluated against a number of highly-PI-resistant HIV-1 strains, and they exhibited improved antiviral activity over darunavir. Two high resolution X-ray structures of 25f- and 25g-bound HIV-1 protease revealed unique hydrogen bonding interactions with the backbone carbonyl group of Gly48 as well as with the backbone NH of Gly48 in the flap region of the enzyme active site. These ligand-binding site interactions are possibly responsible for their potent activity.

  9. Design of HIV-1 Protease Inhibitors with Amino-bis-tetrahydrofuran Derivatives as P2-Ligands to Enhance Backbone-Binding Interactions. Synthesis, Biological Evaluation, and Protein-Ligand X-ray Studies

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Arun K.; Martyr, Cuthbert D.; Osswald, Heather L.; Sheri, Venkat Reddy; Kassekert, Luke A.; Chen, Shujing; Agniswamy, Johnson; Wang, Yuan-Fang; Hayashi, Hironori; Aoki, Manabu; Weber, Irene T.; Mitsuya, Hiroaki (GSU); (Kumamoto); (Purdue)

    2015-10-30

    Structure-based design, synthesis, and biological evaluation of a series of very potent HIV-1 protease inhibitors are described. In an effort to improve backbone ligand–binding site interactions, we have incorporated basic-amines at the C4 position of the bis-tetrahydrofuran (bis-THF) ring. We speculated that these substituents would make hydrogen bonding interactions in the flap region of HIV-1 protease. Synthesis of these inhibitors was performed diastereoselectively. A number of inhibitors displayed very potent enzyme inhibitory and antiviral activity. Inhibitors 25f, 25i, and 25j were evaluated against a number of highly-PI-resistant HIV-1 strains, and they exhibited improved antiviral activity over darunavir. Two high resolution X-ray structures of 25f- and 25g-bound HIV-1 protease revealed unique hydrogen bonding interactions with the backbone carbonyl group of Gly48 as well as with the backbone NH of Gly48 in the flap region of the enzyme active site. These ligand–binding site interactions are possibly responsible for their potent activity.

  10. New validated high-performance liquid chromatographic method for simultaneous analysis of ten flavonoid aglycones in plant extracts using a C18 fused-core column and acetonitrile-tetrahydrofuran gradient.

    Science.gov (United States)

    Olszewska, Monika A

    2012-09-01

    An HPLC method of high resolution has been developed and validated for the simultaneous determination of ten prominent flavonoid aglycones in plant materials using a fused-core C18-silica column (Ascentis® Express, 4.6 mm × 150 mm, 2.7 μm). The separation was accomplished with an acetonitrile-tetrahydrofuran gradient elution at a flow rate of 1 mL/min and temperature of 30°C. UV spectrophotometric detection was employed at 370 nm for flavonols (quercetin [QU], myricetin [MY], isorhamnetin [IS], kaempferol [KA], sexangularetin [SX], and limocitrin [LM]) and 340 nm for flavones (apigenin [AP], acacetin [AC], chrysoeriol [CH], and luteolin [LU]). The high resolution of critical pairs QU/LU (10.50), QU/CH (3.40), AP/CH (2.51), SX/LM (2.30), and IS/KA (2.70) was achieved within 30.3 min. The observed column back pressure was less than 4300 psi, thus acceptable for conventional HPLC equipment. The method was sensitive enough having LODs of 0.115-0.525 ng and good linearity (r > 0.9999) over the test range. The precision values, expressed as RSD values, were Sorbus species. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. The binuclear dual emitter [Br(CO)3Re(PN)(NP)Re(CO)3Br] (PN): 3-chloro-6-(4-diphenylphosphinyl)butoxypyridazine, a new bridging P,N-bidentate ligand resulting from the ring opening of tetrahydrofuran.

    Science.gov (United States)

    Saldías, Marianela; Manzur, Jorge; Palacios, Rodrigo E; Gómez, María L; Fuente, Julio De La; Günther, Germán; Pizarro, Nancy; Vega, Andrés

    2017-01-31

    Lithium diphenylphosphide unexpectedly provokes the ring-opening of tetrahydrofuran (THF) and by reaction with 3,6-dichloropyridazine leads to the formation of the ligand 3-chloro-6-(4-diphenylphosphinyl)butoxypyridazine (P⋯N), which was isolated. The reaction of this ligand with the (Re(CO)3(THF)Br)2 dimer yields the novel complex [Br(CO)3Re(μ-3-chloro-6-(4-diphenylphosphinyl)butoxypyridazine)2Re(CO)3Br] (BrRe(P⋯N)(N⋯P)ReBr), which was crystallized in the form of a chloroform solvate, (C46H40Br2Cl2N4O8P2Re2)·(CHCl3). The monoclinic crystal (P21/n) displays a bimetallic cage structure with a symmetry inversion centre in the middle of the rhenium to rhenium line. The molecule shows two oxidation signals occurring at +1.50 V and +1.76 V which were assigned to the Re(I)/Re(II) and Re(II)/Re(III) metal-centered couples, respectively, while signals observed at -1.38 V and -1.68 V were assigned to ligand centered reductions. Experimental and DFT/TDDFT results indicate that the UV-Vis absorption maximum of BrRe(P⋯N)(N⋯P)ReBr occurring near 380 nm displays a metal to ligand charge transfer (MLCT) character, which is consistent with CV results. Upon excitation at this wavelength, a weak emission (Φem P⋯N ligand's long carbon chain. Measurements in a frozen solvent at 77 K, where vibrational deactivation is hindered, show intense emission associated with the (3)MLCT state. These results demonstrate that BrRe(P⋯N)(N⋯P)ReBr preserves the dual emitting nature previously reported for the mononuclear complex RePNBr, with emission associated with and states.

  12. Excess molar volume, viscosity, and refractive index study for the ternary mixture {l_brace}2-methyl-2-butanol (1) + tetrahydrofuran (2) + propylamine (3){r_brace} at different temperatures. Application of the ERAS-model and Peng-Robinson-Stryjek-Vera equation of state

    Energy Technology Data Exchange (ETDEWEB)

    Fattahi, M. [Faculty of Chemistry, University of Bu-Ali Sina, Hamedan 65174 (Iran, Islamic Republic of); Iloukhani, H., E-mail: iloukhani@basu.ac.i [Faculty of Chemistry, University of Bu-Ali Sina, Hamedan 65174 (Iran, Islamic Republic of)

    2010-11-15

    Densities, viscosities, and refractive indices of the ternary mixture consist of {l_brace}2-methyl-2-butanol (1) + tetrahydrofuran (THF) (2) + propylamine (3){r_brace} at a temperature of 298.15 K and related binary mixtures were measured at temperatures of (288.15, 298.15, and 308.15) K at ambient pressure. Data were used to calculate the excess molar volumes and the deviations of the viscosity and refractive index. The Redlich-Kister and the Cibulka equations were used for correlating binary and ternary properties, respectively. The ERAS-model has been applied for describing the binary and ternary excess molar volumes and also Peng-Robinson-Stryjek-Vera (PRSV) equation of state (EOS) has been used to predict the binary and ternary excess molar volumes and viscosities.

  13. A new tetrahydrofuran lignan diglycoside from Viola tianshanica Maxim.

    Science.gov (United States)

    Qin, Yan; Yin, Chengle; Cheng, Zhihong

    2013-11-04

    A new lignan glycoside, tianshanoside A (1), together with a known phenylpropanoid glycoside, syringin (2) and two known lignan glycosides, picraquassioside C (3), and aketrilignoside B (4), were isolated from the whole plant of Viola tianshanica Maxim. The structure of the new compound was elucidated by extensive NMR (1H, 13C, COSY, HSQC, HMBC and ROESY) and high resolution mass spectrometry analysis. The three lignans 1, 3, and 4 did not exhibit significant cytotoxicity against human gastric cancer Ags cells or HepG2 liver cancer cells. This is the first report of the isolation of a lignan skeleton from the genus Viola L.

  14. A New Tetrahydrofuran Lignan Diglycoside from Viola tianshanica Maxim

    Directory of Open Access Journals (Sweden)

    Yan Qin

    2013-11-01

    Full Text Available A new lignan glycoside, tianshanoside A (1, together with a known phenylpropanoid glycoside, syringin (2 and two known lignan glycosides, picraquassioside C (3, and aketrilignoside B (4, were isolated from the whole plant of Viola tianshanica Maxim. The structure of the new compound was elucidated by extensive NMR (1H, 13C, COSY, HSQC, HMBC and ROESY and high resolution mass spectrometry analysis. The three lignans 1, 3, and 4 did not exhibit significant cytotoxicity against human gastric cancer Ags cells or HepG2 liver cancer cells. This is the first report of the isolation of a lignan skeleton from the genus Viola L.

  15. Dielectric relaxation of amides and tetrahydrofuran polar mixture in ...

    Indian Academy of Sciences (India)

    Author Affiliations. S SAHOO1 S K SIT2. Department of Electronics & Instrumentation Engineering, National Institute of Technology, Silchar 788 010, India; Department of Physics, Dr. Meghnad Saha Institute of Technology, P.O. Debhog, Haldia, Dist:-Purba Medinipore 721 657, India ...

  16. 8-Iodo-quinolinium triiodide tetra-hydro-furan solvate.

    Science.gov (United States)

    Son, Jung-Ho; Hoefelmeyer, James D

    2008-10-04

    The title compound, C(9)H(7)IN(+)·I(3) (-)·C(4)H(8)O, was synthesized from 8-amino-quinoline using the Sandmeyer reaction. The 8-iodo-quinolinium cation is essentially planar and the triiodide ion is almost linear. N-H⋯O hydrogen bonds, and inter-molecular I⋯I [3.7100 (5) Å] and I⋯H inter-actions, between the cation, anion and solvent mol-ecules result in the formation of sheets oriented parallel to the (03) plane. Between the sheets, 8-iodo-quinolinium and triiodide ions are stacked alternately, with I⋯C distances in the range ∼3.8-4.0 Å.

  17. Dielectric relaxation of amides and tetrahydrofuran polar mixture in ...

    Indian Academy of Sciences (India)

    2016-12-06

    Dec 6, 2016 ... attempted by measuring the conductivity of the solution under 9.90 GHz electric field using Debye theory. The estimated relaxation time ... tivity measurement technique is concerned with bound molecular charge of the polar ...... at the site of carbon or nitrogen atoms of the amides and fractional negative ...

  18. CCDC 887968: Experimental Crystal Structure Determination : Dichloro-bis(tricyclohexylphosphine)-(3-phenylindenylidene)-ruthenium tetrahydrofuran solvate

    KAUST Repository

    Urbina-Blanco, C.A.

    2014-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  19. A new efficient and stereospecific conversion of aminodeoxyalditols into aminoalkyl-substituted tetrahydrofurans

    DEFF Research Database (Denmark)

    Norrild, Jens Chr.; Pedersen, Christian; Defaye, Jacques

    1996-01-01

    . In all cases the reactive intermediate is believed to be a 4,5- or 5,6-dioxolenium ion, which can react intramolecularly with a hydroxy group to form a five-membered oxolane ring. The dimethylamino-D-gulo-oxolane was converted into a new 3-hydroxymuscarine isomer, namely, 2,5-anhydro-1,6-dideoxy-1...

  20. Synthesis and phytotoxicity of 4,5 functionalized tetrahydrofuran-2-ones

    Energy Technology Data Exchange (ETDEWEB)

    Resende, Gabriela C.; Alvarenga, Elson S., E-mail: elson@ufv.br [Universidade Federal de Vicosa (UFV), MG (Brazil). Dept. de Quimica; Galindo, Juan C.G.; Macias, Francisco A. [Grupo de Alelopatia, Departamento de Quimica Organica, Facultad de Ciencias, Universidad de Cadiz (Spain)

    2012-12-15

    In this work we report a versatile synthesis of fourteen {gamma}-lactones all structurally related, nine of which are novel compounds, accomplished from the readily available furfural. The phytotoxic activity of the synthesized compounds was evaluated in vitro by the influence on the growth of heat coleoptiles. The percentages of inhibition were mostly small and not statistically different from control after the third dilution (100 Greek-Small-Letter-Mu mol L{sup -1}). In general, {alpha},{beta}-unsaturated lactones presented better activities than the saturated ones. The most active compounds presented 51, 68 and 76% of inhibition in 1000 Greek-Small-Letter-Mu mol L-1. The results indicate that regardless of saturation, the presence of the {gamma}-lactone moiety is important for the bioactivity, but their presence has no implications with potency. (author)

  1. [μ2-Bis(diphenylphosphanylmethane][μ3-bis(diphenylphosphanylmethyl]trichloridotetragold(I tetrahydrofuran disolvate

    Directory of Open Access Journals (Sweden)

    Huan-Huan Wang

    2011-02-01

    Full Text Available The title tetranuclear complex, [Au4(C25H21P2Cl3(C25H22P2]·2C4H8O, features two non-equivalent Ph2PCPPh2 fragments, one of which represents the `complete' molecule (with two H atoms at the central C atom; each of the two P atoms of this molecule is coordinated by an Au atom [Au—P = 2.2256 (13 and 2.2710 (13 Å], and these two Au atoms form an Au—Au bond [3.2945 (3 Å], thus closing the five-membered Au2P2C ring. The first of these Au atoms has a terminal chlorido ligand [Au—Cl = 2.2806 (12 Å], whereas the second Au atom forms a covalent bond with the central C atom of the bis(diphenylphosphinomethyl group [Au—C = 2.114 (5 Å]; the latter group in turn coordinates with its P atoms the gold atoms of the Cl–Au–Au–Cl group [Au—P = 2.2356 (13 and 2.2338 (13, Au—Au = 3.3177 (3, Au—Cl = 2.3091 (12 and 2.2950 (13 Å], thus closing the second Au2P2C ring. The two such rings have different chemical functions, but both exhibit envelope conformations. However, the first (with different substituents at the Au atoms is non-symmetrical with one of the P atoms in the flap position of the envelope; the other one has a conformation with mirror symmetry, and the gold-substituted C atom is displaced by 0.740 (5 Å from the almost exactly planar (r.m.s. deviation = 0.0038 Å Au2P2 group.

  2. Determination of the Solubility Limit of Tris(dibenzylideneacetone) Dipalladium(0) in Tetrahydrofuran/Water Mixtures

    Science.gov (United States)

    Franzen, Stefan

    2011-01-01

    Determination of the solubility limit of a strongly colored organometallic reagent in a mixed-solvent system provides an example of quantitative solubility measurement appropriate to understand polymer, nanoparticle, and other macromolecular aggregation processes. The specific example chosen involves a solution of tris(dibenzylideneacetone)…

  3. Synthesis and phytotoxicity of 4,5 functionalized tetrahydrofuran-2-ones

    OpenAIRE

    Resende,Gabriela C.; Alvarenga,Elson S.; Galindo,Juan C. G.; Macias,Francisco A.

    2012-01-01

    In this work we report a versatile synthesis of fourteen γ-lactones all structurally related, nine of which are novel compounds, accomplished from the readily available furfural. The phytotoxic activity of the synthesized compounds was evaluated in vitro by the influence on the growth of wheat coleoptiles. The percentages of inhibition were mostly small and not statistically different from control after the third dilution (100 µmol L-1). In general, α,β-unsaturated lactones presented better a...

  4. Phase Behaviour, Thermodynamics and Kinetics of Clathrate Hydrate Systems of Carbon Dioxide in Presence of Tetrahydrofuran and Electrolytes

    NARCIS (Netherlands)

    Mohamad Sabil, K. Bin

    2009-01-01

    In view of the possibilities for new development of carbon dioxide hydrate processes, this study focused on experimental measurements to obtain fundamental insight into the phase behaviour and the kinetic of formation of carbon dioxide hydrate forming systems. These data are essential for the

  5. Modeling thermodynamic properties of propane or tetrahydrofuran mixed with carbon dioxide or methane in structure-II clathrate hydrates

    NARCIS (Netherlands)

    Fang, Bin; Ning, Fulong; Cao, Pinqiang; Peng, Li; Wu, Jianyang; Zhang, Zhun; Vlugt, T.J.H.; Kjelstrup, Signe

    2017-01-01

    A sound knowledge of thermodynamic properties of sII hydrates is of great importance to understand the stability of sII gas hydrates in petroleum pipelines and in natural settings. Here, we report direct molecular dynamics (MD) simulations of the thermal expansion coefficient, the

  6. Preparative gel permeation chromatographic separation of solvent refined coal. [Tetrahydrofuran and chloroform; evaluation of 3 column packings

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, W.M.; Wooton, D.L.; Dorn, H.C.; Taylor, L.T.

    1977-04-01

    A preparative quantitative separation of THF- and CHCl/sub 3/-soluble solvent refined coal (Pittsburgh No. 8) has been demonstrated employing gel permeation chromatographic techniques utilizing three column packings: a styrene--divinyl benzene packing (Bio-Beads S-X4), a cross-linked poly(N-acryloylmorpholine) polymer (Enzacryl Gel K-1), and a modified alkylated dextran (Sephadex LH-20). Each packing material is evaluated based on the extent and time of separation and the cost of materials. The percent recovery in the Bio-Bead case is greater than 95 percent. Average molecular weights via vapor phase osmometry on the four sized fractions of THF-soluble SRC from Bio-Beads suggests that a separation according to molecular weight has been achieved. The description of a short tapered glass column to economically carry out these preparative separations is described.

  7. Bis-Tetrahydrofuran: a Privileged Ligand for Darunavir and a New Generation of HIV Protease Inhibitors That Combat Drug Resistance

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Arun K.; Sridhar, Perali Ramu; Kumaragurubaran, Nagaswamy; Koh, Yasuhiro; Weber, Irene T.; Mitsuya, Hiroaki (Kumamoto Univ, Japan); (GSU); (NIH); (Purdue)

    2008-06-06

    Two inhibitors that incorporate bis-THF as an effective high-affinity P{sub 2} ligand for the HIV-1 protease substrate binding site maintain impressive potency against mutant strains resistant to currently approved protease inhibitors. Crystallographic structures of protein-ligand complexes help to explain the superior antiviral property of these inhibitors and their potency against a wide spectrum of HIV-1 strains.

  8. CCDC 808552: Experimental Crystal Structure Determination : (4,7-Diphenyl-1,10-phenanthroline)(trifluoromethyl)-copper tetrahydrofuran solvate

    KAUST Repository

    Weng, Zhiqiang

    2011-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  9. CCDC 808551: Experimental Crystal Structure Determination : (4,7-Diphenyl-1,10-phenanthroline)-trifluoromethyl-silver tetrahydrofuran solvate

    KAUST Repository

    Weng, Zhiqiang

    2011-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  10. Crystal structure of bis[1,3-bis(2,6-diisopropylphenylimidazol-2-ylidene]silver(I chloride tetrahydrofuran monosolvate

    Directory of Open Access Journals (Sweden)

    Inge Sänger

    2015-05-01

    Full Text Available In the title salt, [Ag(C27H36N22]Cl·C4H8O, the AgI atom is coordinated by two 1,3-bis(2,6-dimethylphenylimidazol-2-ylidene ligands. The imidazole rings are inclined to one another by 46.69 (13° and the benzene rings in each ligand are almost normal to the imdazole ring to which they are attached, with dihedral angles varying from 82.39 (13 to 88.27 (12°. There are C—H...π interactions present in the cation, involving the two ligands, and the solvent molecule is linked to the cation via a C—H...O hydrogen bond. In the crystal, molecules are linked by trifurcated C—H...(Cl,Cl,Cl hydrogen bonds, forming slabs parallel to (101. One isopropyl group is disordered over two sets of sites with an occupancy ratio of 0.447 (17:0.553 (17 and the THF molecule is disordered over two positions with an occupancy ratio of 0.589 (6:0.411 (6.

  11. CCDC 873769: Experimental Crystal Structure Determination : (1,3-bis(2,6-Di-isopropylphenyl)imidazol-2-ylidene)-(formato-O)-hydrido-(tricyclohexylphosphine)-palladium tetrahydrofuran solvate

    KAUST Repository

    Broggi, Julie

    2014-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  12. Experimental observations on the competing effect of tetrahydrofuran and an electrolyte and the strength of hydrate inhibition among metal halides in mixed CO{sub 2} hydrate equilibria

    Energy Technology Data Exchange (ETDEWEB)

    Sabil, Khalik M., E-mail: khalik_msabil@petronas.com.m [Delft University of Technology, Laboratory of Process Equipment, Mechanical, Maritime and Materials Engineering, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Universiti Teknologi PETRONAS, Chemical Engineering Programme, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Roman, Vicente R.; Witkamp, Geert-Jan [Delft University of Technology, Laboratory of Process Equipment, Mechanical, Maritime and Materials Engineering, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Peters, Cor J., E-mail: C.J.Peters@tudelft.n [Delft University of Technology, Laboratory of Process Equipment, Mechanical, Maritime and Materials Engineering, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Petroleum Institute, Chemical Engineering Program, Bu Hasa Building, Room 2207A, P.O. Box 2533, Abu Dhabi (United Arab Emirates)

    2010-03-15

    In the present work, experimental data on the equilibrium conditions of mixed CO{sub 2} and THF hydrates in aqueous electrolyte solutions are reported. Seven different electrolytes (metal halides) were used in this work namely sodium chloride (NaCl), calcium chloride (CaCl{sub 2}), magnesium chloride (MgCl{sub 2}), potassium bromide (KBr), sodium fluoride (NaF), potassium chloride (KCl), and sodium bromide (NaBr). All equilibrium data were measured by using Cailletet apparatus. Throughout this work, the overall concentration of CO{sub 2} and THF were kept constant at (0.04 and 0.05) mol fraction, respectively, while the concentration of electrolytes were varied. The experimental temperature ranged from (275 to 305) K and pressure up 7.10 MPa had been applied. From the experimental results, it is concluded that THF, which is soluble in water is able to suppress the salt inhibiting effect in the range studied. In all quaternary systems studied, a four-phase hydrate equilibrium line was observed where hydrate (H), liquid water (L{sub W}), liquid organic (L{sub V}), and vapour (V) exist simultaneously at specific pressure and temperature. The formation of this four-phase equilibrium line is mainly due to a liquid-liquid phase split of (water + THF) mixture when pressurized with CO{sub 2} and the split is enhanced by the salting-out effect of the electrolytes in the quaternary system. The strength of hydrate inhibition effect among the electrolytes was compared. The results shows the hydrate inhibiting effect of the metal halides is increasing in the order NaF < KBr < NaCl < NaBr < CaCl{sub 2} < MgCl{sub 2}. Among the cations studied, the strength of hydrate inhibition increases in the following order: K{sup +} < Na{sup +} < Ca{sup 2+} < Mg{sup 2+}. Meanwhile, the strength of hydrate inhibition among the halogen anion studied decreases in the following order: Br{sup -} > Cl{sup -} > F{sup -}. Based on the results, it is suggested that the probability of formation and the strength of ionic-hydrogen bond between an ion and water molecule and the effects of this bond on the ambient water network are the major factors that contribute to hydrate inhibition by electrolytes.

  13. Chloridonitrosyl[meso-5,10,15,20-tetrakis(p-tolylporphyrinato-κ4N,N′,N′′,N′′′]osmium(II tetrahydrofuran tetrasolvate

    Directory of Open Access Journals (Sweden)

    Li Chen

    2011-02-01

    Full Text Available The title compound, [OsCl(NO(C48H36N4]·4C4H8O, is a six-coordinate osmium(II porphyrin complex with nitrosyl (NO and chloride (Cl ligands trans to each other in an octahedral geometry. The metal complex lies on a fourfold rotation axis that passes through the Os, N, O and Cl atoms. The NO and Cl ligands are disordered in an 0.511 (12:0.486 (12 ratio.

  14. {μ-1,2-Bis[bis(4-methoxyphenylphosphanyl]-1,2-dimethylhydrazine-κ2P:P′}bis[chloridogold(I] tetrahydrofuran disolvate

    Directory of Open Access Journals (Sweden)

    Frederik H. Kriel

    2011-08-01

    Full Text Available The title compound, [Au2Cl2(C30H34N2O4P2]·2C4H8O, is formed from a bidentate phosphine ligand complexed to two almost linearly coordinated gold(I atoms [P—Au—Cl = 175.68 (3 Å]. The nuclei are 3.122 (2 Å apart. The molecule exhibits a twofold rotation axis.

  15. P2' benzene carboxylic acid moiety is associated with decrease in cellular uptake: evaluation of novel nonpeptidic HIV-1 protease inhibitors containing P2 bis-tetrahydrofuran moiety.

    Science.gov (United States)

    Yedidi, Ravikiran S; Maeda, Kenji; Fyvie, W Sean; Steffey, Melinda; Davis, David A; Palmer, Ira; Aoki, Manabu; Kaufman, Joshua D; Stahl, Stephen J; Garimella, Harisha; Das, Debananda; Wingfield, Paul T; Ghosh, Arun K; Mitsuya, Hiroaki

    2013-10-01

    GRL007 and GRL008, two structurally related nonpeptidic human immunodeficiency virus type 1 (HIV-1) protease inhibitors (PIs) containing 3(R),3a(S),6a(R)-bis-tetrahydrofuranylurethane (bis-THF) as the P2 moiety and a sulfonamide isostere consisting of benzene carboxylic acid and benzene carboxamide as the P2' moiety, respectively, were evaluated for their antiviral activity and interactions with wild-type protease (PR(WT)). Both GRL007 (Ki of 12.7 pM with PR(WT)) and GRL008 (Ki of 8.9 pM) inhibited PR(WT) with high potency in vitro. X-ray crystallographic analysis of PR(WT) in complex with GRL007 or GRL008 showed that the bis-THF moiety of both compounds has three direct polar contacts with the backbone amide nitrogen atoms of Asp29 and Asp30 of PR(WT). The P2' moiety of both compounds showed one direct contact with the backbone of Asp30' and a bridging polar contact with Gly48' through a water molecule. Cell-based antiviral assays showed that GRL007 was inactive (50% effective concentration [EC50] of >1 μM) while GRL008 was highly active (EC50 of 0.04 μM) against wild-type HIV-1. High-performance liquid chromatography (HPLC)/mass spectrometry-based cellular uptake assays showed 8.1- and 84-fold higher intracellular concentrations of GRL008 than GRL007 in human MT-2 and MT-4 cell extracts, respectively. Thus, GRL007, in spite of its favorable enzyme-inhibitory activity and protease binding profile, exhibited a lack of antiviral activity in cell-based assays, most likely due to its compromised cellular uptake associated with its P2' benzene carboxylic acid moiety. The anti-HIV-1 potency, favorable toxicity, and binding profile of GRL008 suggest that further optimization of the P2' moiety may improve its antiretroviral features.

  16. Design of gem-difluoro-bis-tetrahydrofuran as P2 ligand for HIV-1 protease inhibitors to improve brain penetration: synthesis, X-ray studies, and biological evaluation.

    Science.gov (United States)

    Ghosh, Arun K; Yashchuk, Sofiya; Mizuno, Akira; Chakraborty, Nilanjana; Agniswamy, Johnson; Wang, Yuan-Fang; Aoki, Manabu; Gomez, Pedro Miguel Salcedo; Amano, Masayuki; Weber, Irene T; Mitsuya, Hiroaki

    2015-01-01

    The structure-based design, synthesis, biological evaluation, and X-ray structural studies of fluorine-containing HIV-1 protease inhibitors are described. The synthesis of both enantiomers of the gem-difluoro-bis-THF ligands was carried out in a stereoselective manner using a Reformatskii-Claisen reaction as the key step. Optically active ligands were converted into protease inhibitors. Two of these inhibitors, (3R,3aS,6aS)-4,4-difluorohexahydrofuro[2,3-b]furan-3-yl(2S,3R)-3-hydroxy-4-((N-isobutyl-4-methoxyphenyl)sulfonamido)-1-phenylbutan-2-yl) carbamate (3) and (3R,3aS,6aS)-4,4-difluorohexahydrofuro[2,3-b]furan-3-yl(2S,3R)-3-hydroxy-4-((N-isobutyl-4-aminophenyl)sulfonamido)phenylbutan-2-yl) carbamate (4), exhibited HIV-1 protease inhibitory Ki values in the picomolar range. Both 3 and 4 showed very potent antiviral activity, with respective EC50 values of 0.8 and 3.1 nM against the laboratory strain HIV-1LAI . The two inhibitors exhibited better lipophilicity profiles than darunavir, and also showed much improved blood-brain barrier permeability in an in vitro model. A high-resolution X-ray structure of inhibitor 4 in complex with HIV-1 protease was determined, revealing that the fluorinated ligand makes extensive interactions with the S2 subsite of HIV-1 protease, including hydrogen bonding interactions with the protease backbone atoms. Moreover, both fluorine atoms on the bis-THF ligand formed strong interactions with the flap Gly 48 carbonyl oxygen atom. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. CCDC 1050930: Experimental Crystal Structure Determination : Chloro-(N,N'-(pyridine-2,6-diyl)bis(P,P-di-t-butyl(phosphinous amide)))-rhodium tetrahydrofuran solvate

    KAUST Repository

    Wang, Yuan

    2015-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  18. Ferrocene adsorbed into the porous octakis(hydridodimethylsiloxy)silsesquioxane after thermolysis in tetrahydrofuran media: An applied surface for ascorbic acid determination

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro do Carmo, Devaney, E-mail: docarmo@dfq.feis.unesp.br [Faculdade de Engenharia de Ilha Solteira UNESP - Univ Estadual Paulista, Departamento de Fisica e Quimica, Av. Brasil Centro, 56 CEP 15385-000, Ilha Solteira, SP (Brazil); Lataro Paim, Leonardo; Ramos Stradiotto, Nelson [Instituto de Quimica de Araraquara UNESP - Univ Estadual Paulista, Rua Francisco Degni s/n, CEP 14801-970, Araraquara, SP (Brazil)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Octakis(hydridodimethylsiloxi)silsesquioxane was synthesized and Ferrocene was adsorbed. Black-Right-Pointing-Pointer Polymeric net through electrostatic interactions was observed. Black-Right-Pointing-Pointer The novel materials presents electroacatalytic activity for Ascorbic acid. -- Abstract: Octakis(hydridodimethylsiloxi)silsesquioxane (Q{sub 8}M{sub 8}{sup H}) was synthesized and Ferrocene was adsorbed in a polymeric net through electrostatic interactions, with anion forming after the cleavage of any siloxy groups (ESFc). The nanostructured materials (Q{sub 8}M{sub 8}{sup H} and EsFc) were characterized by Fourier transform infrared spectra (FT-IR), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), Thermogravimetric analyses and Voltammetric technique The cyclic voltammograms of the graphite paste electrode modified with ESFc showed one redox couple with E{sup 0} Prime = 0.320 V (1.0 mol L{sup -1} NaCl, v = 50 mV s{sup -1}), with a diffusion-controlled process and the redox process shows electrocatalytic activity for the oxidation of ascorbic acid.

  19. Excess enthalpies of the ternary mixtures: {l_brace}tetrahydrofuran + 3-methylpentane + (octane or decane){r_brace} at the temperature 298.15 K[Excess enthalpy; Ternary mixture; Tetrahydrofuran; 3-Methylpentane; n-Octane; n-Decane; Liebermann-Fried model

    Energy Technology Data Exchange (ETDEWEB)

    Wang Zhaohui; Benson, George C. E-mail: gbenson@eng.uottawa.ca; Lu, Benjamin C.-Y

    2003-10-01

    Measurements of excess molar enthalpies at the temperature 298.15 K in a flow microcalorimeter, are reported for the two ternary mixtures {l_brace}X{sub 1}C{sub 4}H{sub 8}O + X{sub 2}CH{sub 3}CH{sub 2}CH(CH{sub 3})CH{sub 2}CH{sub 3} + (1-X{sub 1}-X{sub 2})CH{sub 3}(CH{sub 2}){sub v-2}CH{sub 3}{r_brace} with v=8 and 10. Smooth representations of the results are described and used to construct constant-enthalpy contours on Roozeboom diagrams. It is shown that useful estimates of the ternary enthalpies can be obtained from the Liebermann-Fried model, using only the physical properties of the components and their binary mixtures.

  20. A conserved hydrogen-bonding network of P2 bis-tetrahydrofuran-containing HIV-1 protease inhibitors (PIs) with a protease active-site amino acid backbone aids in their activity against PI-resistant HIV.

    Science.gov (United States)

    Yedidi, Ravikiran S; Garimella, Harisha; Aoki, Manabu; Aoki-Ogata, Hiromi; Desai, Darshan V; Chang, Simon B; Davis, David A; Fyvie, W Sean; Kaufman, Joshua D; Smith, David W; Das, Debananda; Wingfield, Paul T; Maeda, Kenji; Ghosh, Arun K; Mitsuya, Hiroaki

    2014-07-01

    In the present study, GRL008, a novel nonpeptidic human immunodeficiency virus type 1 (HIV-1) protease inhibitor (PI), and darunavir (DRV), both of which contain a P2-bis-tetrahydrofuranyl urethane (bis-THF) moiety, were found to exert potent antiviral activity (50% effective concentrations [EC50s], 0.029 and 0.002 μM, respectively) against a multidrug-resistant clinical isolate of HIV-1 (HIVA02) compared to ritonavir (RTV; EC50, >1.0 μM) and tipranavir (TPV; EC50, 0.364 μM). Additionally, GRL008 showed potent antiviral activity against an HIV-1 variant selected in the presence of DRV over 20 passages (HIVDRV(R)P20), with a 2.6-fold increase in its EC50 (0.097 μM) compared to its corresponding EC50 (0.038 μM) against wild-type HIV-1NL4-3 (HIVWT). Based on X-ray crystallographic analysis, both GRL008 and DRV showed strong hydrogen bonds (H-bonds) with the backbone-amide nitrogen/carbonyl oxygen atoms of conserved active-site amino acids G27, D29, D30, and D30' of HIVA02 protease (PRA02) and wild-type PR in their corresponding crystal structures, while TPV lacked H-bonds with G27 and D30' due to an absence of polar groups. The P2' thiazolyl moiety of RTV showed two conformations in the crystal structure of the PRA02-RTV complex, one of which showed loss of contacts in the S2' binding pocket of PRA02, supporting RTV's compromised antiviral activity (EC50, >1 μM). Thus, the conserved H-bonding network of P2-bis-THF-containing GRL008 with the backbone of G27, D29, D30, and D30' most likely contributes to its persistently greater antiviral activity against HIVWT, HIVA02, and HIVDRV(R)P20. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  1. [Cu2R2BrLi(thf)3], R = Si(SiMe3)3–a complex containing five-coordinate silicon in a three-centre two-electron bond (thf = tetrahydrofuran)

    OpenAIRE

    Heine, Andreas; Herbst-Irmer, Regine; Stalke, Dietmar

    1993-01-01

    The title compound is obtained from the reaction of (Me3Si)3SiLi(thf)3 with CuBr in n-hexane and structurally characterised by X-ray diffraction; in [Cu2R2BrLi(thf)3], R = Si(SiMe3)3 one silyl ligand is bridging a very short Cu–Cu bond, resulting in a three-centre two-electron bond, while the second is terminally bound to copper; the other copper atom is linked to a lithium atom via a Cu Br Li bridge. peerReviewed

  2. Mitochondrial protection by the mixed muscarinic/σ1 ligand ANAVEX2-73, a tetrahydrofuran derivative, in Aβ25-35 peptide-injected mice, a nontransgenic Alzheimer's disease model

    Directory of Open Access Journals (Sweden)

    Valentine eLahmy

    2015-01-01

    Full Text Available Alzheimer’s disease (AD, the most prevalent dementia in the elderly, is characterized by progressive synaptic and neuronal loss. Mitochondrial dysfunctions have been consistently reported as an early event in AD and appear before Aβ deposition and memory decline. In order to define a new neuroprotectant strategy in AD targeting mitochondrial alterations, we develop tetrahydro-N,N-dimethyl-2,2-diphenyl-3-furanmethanamine (ANAVEX2-73, AE37, a mixed muscarinic receptor ligand and a sigma-1 receptor (σ1R agonist. We previously reported that ANAVEX2-73 shows anti-amnesic and neuroprotective activities in mice injected ICV with oligomeric amyloid-β25-35 peptide (Aβ25-35. The σ1R is present at mitochondria-associated endoplasmic reticulum membranes, where it acts as a sensor/modulator of endoplasmic reticulum (ER stress responses and local Ca2+ exchanges with the mitochondria. We therefore evaluated the effect of ANAVEX2-73 and PRE-084, a reference σ1R agonist, on preservation of mitochondrial integrity in Aβ25-35-injected mice. In isolated mitochondria from hippocampus preparations of Aβ25-35 injected animals, we measured respiration rates, complex activities, lipid peroxidation, Bax/Bcl-2 ratios and cytochrome c release into the cytosol. Five days after Aβ25-35 injection, mitochondrial respiration in mouse hippocampus was altered. ANAVEX2-73 (0.01-1 mg/kg IP restored normal respiration and PRE-084 (0.5-1 mg/kg IP increased respiration rates. Both compounds prevented Aβ25-35-induced increases in lipid peroxidation levels, Bax/Bcl-2 ratio and cytochrome c release into the cytosol, all indicators of increased toxicity. ANAVEX2-73 and PRE-084 efficiently prevented the mitochondrial respiratory dysfunction and resulting oxidative stress and apoptosis. The σ1R, targeted selectively or non-selectively, therefore appears as a valuable target for protection against mitochondrial damages in AD.

  3. Material Database for Additive Manufacturing Techniques

    Science.gov (United States)

    2017-12-01

    Weldon 2 PLA - - -Tetrahydrofuran -Weldon 3 ABS - - Acetone 4 ABS - - Acetone 5 PLA - - -Tetrahydrofuran -Weldon 6 ABS - - Acetone 7...ABS - - Acetone 8 ABS - - Acetone 9 ABS - - Acetone 10 Conductive PLA #VALUE! #VALUE! -Tetrahydrofuran -Weldon 11 SS PLA #VALUE! #VALUE...Limonene Bad print quality 17 ABS - - Acetone *Note different thickness 18 ABS - - Acetone *Note different thickness 19 ABS - - Acetone

  4. Application of selectively acylated glycosides for the α-galactosidase-catalyzed synthesis of disaccharides

    National Research Council Canada - National Science Library

    Simerská, P; Kuzma, M; Pišvejcová, A; Weignerová, L; Macková, M; Riva, S; Křen, V

    2003-01-01

    .... A series of water-miscible organic solvents (acetone, acetonitrile, dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, 2-methoxyethanol, pyridine, 2-methylpropan-2-ol, tetrahydrofuran, propargyl alcohol...

  5. Application of selectively acylated glycosides for the [alpha]-galactosidase-catalyzed synthesis of disaccharides

    National Research Council Canada - National Science Library

    P Simerská; M Kuzma; A Pisvejcová; L Weignerová; M Macková; S Riva; V Kren

    2003-01-01

    .... A series of water-miscible organic solvents (acetone, acetonitrile, dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, 2-methoxyethanol, pyridine, 2-methylpropan-2-ol, tetrahydrofuran, propargyl alcohol...

  6. CCDC 1055170: Experimental Crystal Structure Determination : Methyl 5,5-difluoro-1,3,7,9-tetramethyl-2,8-bis(triphenylvinyl)-5H-4lambda5,5lambda5-dipyrrolo[1,2-c:2',1'-f][1,3,2]diazaborinine-10-carboxylate tetrahydrofuran solvate

    KAUST Repository

    Chua, Ming Hui

    2015-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  7. Racemic methyl 3,10-dioxa-2-azatricyclo[6.2.1.02,6]undecane-4- carboxylate

    KAUST Repository

    Moosa, Basem

    2011-04-29

    The structure of the racemic title compound, C10H 15NO4, consists of a tricyclic skeleton comprising a six-membered piperidine ring and five-membered isoxazolidine and tetrahydrofuran rings. The piperidine ring adopts a distorted chair conformation, while the isoxazolidine and tetrahydrofuran rings have envelope conformations.

  8. Structural and electrochemical properties of -tetrabromo ...

    Indian Academy of Sciences (India)

    porphinato copper(II) tetrahydrofuran solvate was examined and it features enhanced non-planar distortion of the porphyrin ring. The normal coordinate structural decomposition (NSD) analysis for the out-of-plane displacement of atoms of the ...

  9. Gene expression profiling of sesaminol triglucoside and its tetrahydrofuranoid metabolites in primary rat hepatocytes.

    Science.gov (United States)

    Jan, Kuo-Ching; Yang, Binghuei-Barry; Liu, Tristan C

    2014-12-01

    Sesaminol triglucoside is a major lignin in sesame meal and has a methylenedioxyphenyl group and multiple functions in vivo. As a tetrahydrofurofuran type lignan, sesaminol triglucoside is metabolized to mammalian lignans. This investigation studies the effect of sesaminol triglucoside and its tetrahydrofuranoid metabolites (sesaminol, 2-episesaminol, hydroxymethyl sesaminol-tetrahydrofuran, enterolactone, and enterodiol) on gene expression in primary rat hepatocytes using a DNA microarray. Sesame lignans significantly affected the expression of xenobiotic-induced transcripts of cytochrome P450, solute carrier (SLC), and ATP-binding cassette (ABC) transporters. Changes in gene expression were generally greater in response to metabolites with methylenedioxyphenyl moieties (sesaminol triglucoside, sesaminol, and 2-episesaminol) than to the tetrahydrofuranoid metabolites (hydroxymethyl sesaminol-tetrahydrofuran, enterolactone, and enterodiol). Tetrahydrofuran lignans, such as sesaminol triglucoside, sesamin, hydroxymethyl sesaminol-tetrahydrofuran, and sesaminol changed the expression of ABC transporters.

  10. Synthesis of Acetogenin Analogs as Potential Therapeutics for Treating Prostate Cancer

    National Research Council Canada - National Science Library

    Pagenkopf, Brian

    2002-01-01

    .... As an additional bonus from this work, a new cobalt complex was developed that catalyzes the stereoselective oxidative cyclization of bis-homoallylic alcohols to trans-tetrahydrofurans in high yield...

  11. Synthesis of low polydisperse isotactic poly(N-isopropylacrylamide)s ...

    Indian Academy of Sciences (India)

    glass distillation appa- ratus. Tetrahydrofuran (THF) and hexane were used without purification. 2.2 Synthesis and Characterization of PNIPAMs. (Table 1). The polymerization was performed in different com- positions of methanol-water mixture.

  12. Stereochemical Complexity in Oxocarbenium-Ion-Initiated Cascade Annulations for the Synthesis of the ABCD Core of Mattogrossine.

    Science.gov (United States)

    Kong, Aidi; Andreansky, Eric S; Blakey, Simon B

    2017-04-21

    Mattogrossine is an indole alkaloid isolated from Strychnos mattogrossensis that contains an unusual tetrahydrofuran ring with a concomitant hemiacetal in its structure. While tetrahydrofuran intermediates have been used in the synthesis of other strychnos alkaloids, no investigations have been performed into the synthesis of alkaloids containing this structure. We have developed an oxocarbenium-ion-initiated cascade annulation that provides us access to the ABCD ring structure of mattogrossine.

  13. The Use of a Flexible Calix[4]arene Template to Stabilize a Cyclooctatetraindiyl Samarium-Potassium Complex

    Directory of Open Access Journals (Sweden)

    Geoffroy Guillemot

    2013-01-01

    Full Text Available A sandwich compound of cyclooctatetraendiyl (COT2− samarium-potassium was synthesized and analyzed using a flexible calix[4]arene dianion. This compound, [p-tBu-calix[4]-(OMe2(O2]arenediyl-samarium-(η8-cyclooctatetraendiyl-potassium (tetrahydrofurane3, is constructed as a linear sequence L-Sm--K-, where L, , and are specific ligands with L = O,O-dimethyl-calix[4]arene2−, = cyclo-octatetraendiyl, and = tetrahydrofurane templates.

  14. Agastinol and agastenol, novel lignans from Agastache rugosa and their evaluation in an apoptosis inhibition assay.

    Science.gov (United States)

    Lee, Choonghwan; Kim, Hyuna; Kho, Yunghee

    2002-03-01

    Investigation of the whole plant of Agastache rugosa resulted in the isolation of two new lignan compounds. Their structures were elucidated as (8S,7'R,8'S)-4-hydroxybenzoic acid 4-(4-hydroxy-3-methoxybenzyl)-2-(4-hydroxy-3-methoxyphenyl)tetrahydrofuran-3-ylmethyl ester (agastinol, 1) and (7'R,8'S)-4-hydroxybenzoic acid 4-(hydroxy-3-methoxybenzylidene)-2-(4-hydroxy-3-methoxyphenyl)-tetrahydrofuran-3-ylmethyl ester (agastenol, 2). Agastinol and agastenol inhibited etoposide-induced apoptosis in U937 cells with IC50 values of 15.2 and 11.4 microg/mL, respectively.

  15. Direct Observations of Three Dimensional Growth of Hydrates Hosted in Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Kerkar, P.; Jones, K; Kleinberg, R; Lindquist, W; Tomov, S; Feng, H; Mahajan, D

    2009-01-01

    The visualization of time-resolved three-dimensional growth of tetrahydrofuran hydrates with glass spheres of uniform size as porous media using synchrotron x-ray computed microtomography is presented. The images of hydrate patches, formed from excess tetrahydrofuran in aqueous solution, show random nucleation and growth concomitant with grain movement but independent of container-wall effect. Away from grain surfaces, hydrate surface curvature was convex showing that liquid, not hydrate, was the wetting phase, similar to ice growth in porous media. The extension of the observed behavior to methane hydrates could have implications in understanding their role in seafloor stability and climate change.

  16. Evaluation of miscibility of poly(epichlorohydrin-co-ethylene oxide) and poly(methylmethacrylate) blends; Avaliacao da miscibilidade de blendas de poli(epicloridrina-co-oxido de etileno) e poli(metacrilato de metila)

    Energy Technology Data Exchange (ETDEWEB)

    Turchete, Renato; Felisberti, Maria Isabel [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica

    1999-07-01

    The miscibility of blends of poly(methylmethacrylate), (PMMA) and poly(epichlorohydrin-co-ethylene oxide), (ECO) were investigated by differential scanning calorimetry. The ECO was fractionated using two different systems: a solvent-non solvent system and by cooling the solution in tetrahydrofuran in the temperature range from 20 to 0 deg C. The fractions with different composition and molecular weight were used to prepare the blends by casting from solution in tetrahydrofuran. The blends exhibit two glass transitions shifted in relation to the glass transitions of the pure polymers, indicating a partial miscibility. Blends containing copolymer richer in epichlorohydrin segments were more miscible than blends of non-fractionated ECO. (author)

  17. Terahertz Time Domain Spectroscopy for Structure-II Gas Hydrates

    DEFF Research Database (Denmark)

    Takeya, Kei; Zhang, Caihong; Kawayama, Iwao

    2009-01-01

    For the nondestructive inspection of gas hydrates, terahertz (THz) time-domain spectroscopy (TDS) was applied to tetrahydrofuran (THF) hydrate and propane hydrate. The absorption of propane hydrate monotonically increases with frequency, similar to the case of ice, while THF hydrate has a charact......For the nondestructive inspection of gas hydrates, terahertz (THz) time-domain spectroscopy (TDS) was applied to tetrahydrofuran (THF) hydrate and propane hydrate. The absorption of propane hydrate monotonically increases with frequency, similar to the case of ice, while THF hydrate has...

  18. Ring-opening of cyclic ethers with carbon–carbon bond formation by Grignard reagents

    DEFF Research Database (Denmark)

    Christensen, Stig Holden; Holm, Torkil; Madsen, Robert

    2014-01-01

    The ring-opening of cyclic ethers with concomitant C–C bond formation was studied with a number of Grignard reagents. The transformation was performed in a sealed vial by heating to ∼160 °C in an aluminum block or at 180 °C in a microwave oven. Good yields of the product alcohols were obtained...... with allyl- and benzylmagnesium halides when the ether was tetrahydrofuran or 3,3-dimethyloxetane. Lower yields were obtained with substituted tetrahydrofurans while no ring-opening was observed with tetrahydropyran. Only highly reactive allyl and benzyl Grignard reagents participated in the transformation...

  19. Studies on the acaricidal mechanism of the active components from neem (Azadirachta indica) oil against Sarcoptes scabiei var. cuniculi.

    Science.gov (United States)

    Chen, Zhen-zhen; Deng, Yun-xia; Yin, Zhong-qiong; Wei, Qin; Li, Mei; Jia, Ren-yong; Xu, Jiao; Li, Li; Song, Xu; Liang, Xiao-xia; Shu, Gang; He, Chang-liang; Gu, Xiao-bin; Lv, Cheng; Yin, Lizi

    2014-08-29

    Octadecanoic acid-3,4-tetrahydrofuran diester, isolated from neem (Azadirachta indica) oil, exhibited potent acaricidal activity against Sarcoptes scabiei var. cuniculi. In this paper, the acaricidal mechanism of octadecanoic acid-3,4-tetrahydrofuran diester against Sarcoptes scabiei var. cuniculi was evaluated based on pathologic histology and enzyme activities. The results showed that after compound treatment for 24h at a concentration of 20mg/mL, the lesions of mites were prominent under transmission electron microscopy. The lesions consisted of the lysis of dermis cell membranes and cell nuclear membranes, mitochondrial morphological abnormalities, the drop of spinal disorders, and mitochondrial vacuolization. The activity of superoxide dismutase (SOD), peroxidase (POD), glutathione-s-transferases (GSTs), and Ca(2+)-ATPase of mites significantly changed after treatment with octadecanoic acid-3,4-tetrahydrofuran diester compared with the control group. The activities of SOD, POD, and Ca(2+)-ATPase were significantly suppressed, whereas that of GSTs was activated. These results indicated that the mechanism of the acaricidal activity of octadecanoic acid-3,4-tetrahydrofuran diester was mainly achieved through interference with the energy metabolism of mites, thus resulting in insect death. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. A new one-pot synthesis of 1,2,4-oxadiazoles from aryl nitriles ...

    Indian Academy of Sciences (India)

    by esterification in tetrahydrofuran (THF) and cycliza- tion/dehydration in dimethyl sulphoxide (DMSO) to give 1,2,4-oxadiazole (scheme 1). In general, there is no need to remove THF after esterification and both cyclizations/dehydrations are facilitated in high tempe- ratures by addition of DMSO, and therefore these three.

  1. 2-Alquil-4-Hidroxi-Tetrahidrofuranos de la Pulpa del Aguacate

    Directory of Open Access Journals (Sweden)

    Alfonso Rivas-Gil

    2006-12-01

    Full Text Available From a hexane extract of avocado pulp (Persea americana Mill., an 1:3 mixture of 2-(heptadec-16-enyl- and 2-(heptadec-16-ynyl-4-hydroxy -tetrahydrofurans was characterized by NMR techniques. These compounds have not been previously reported from natural sources.

  2. Lecithin Complex

    African Journals Online (AJOL)

    China). Lecithin from soya bean was a product of. Sangon (Shanghai, China). Methanol of HPLC grade was purchased from Tedia (USA). Other chemicals used were of analytical grade. Preparation of polydatin-lecithin complex. Polydatin (200 mg) and lecithin (400 mg) were dissolved in 50 mL of tetrahydrofuran and stirred.

  3. Formation Kinetics of Aqueous Suspensions of Fullerenes:Meeting in New Orleans.

    Science.gov (United States)

    Stable colloidal suspension of C60 is commonly achieved through various solvent exchange techniques. Nevertheless, the additives such as tetrahydrofuran may be retained in the C60 aggregates, which may influence the surface properties of the suspension. In this study, colloidal...

  4. Mechanistic study of trivalent europium transport through supported liquid membranes (SLMs) and a novel immobilized phase solvent extraction (IPSE) system

    NARCIS (Netherlands)

    Boerrigter, H.; Tomasberger, Tanja; Booij, Arend S.; Verboom, Willem; Reinhoudt, David; de Jong, Feike

    2000-01-01

    As a new method of membrane formation, we have investigated microcellular foaming of thin (100 μm) polysulfone films containing varying trace concentrations of tetrahydrofuran using carbon dioxide as a physical blowing agent. Membrane morphologies were obtained by first saturating the polymer with

  5. Novel open-cellular polysulfone morphologies produced with trace concentrations of solvens as pore opener

    NARCIS (Netherlands)

    Krause, B.; Boerrigter, M.E.; van der Vegt, N.F.A.; Strathmann, H.; Wessling, Matthias

    2001-01-01

    As a new method of membrane formation, we have investigated microcellular foaming of thin (not, vert, similar100 ¿m) polysulfone films containing varying trace concentrations of tetrahydrofuran using carbon dioxide as a physical blowing agent. Membrane morphologies were obtained by first saturating

  6. Synthesis and unexpected reactivity of [Ru(η -cymene)Cl2(PPh2Cl ...

    Indian Academy of Sciences (India)

    The source of hydrogen is not unam- biguously identified due to the exchangeable nature of the P-H bond. 2. Experimental. 2.1 Materials and methods. All reactions and manipulations were routinely perform- ed under nitrogen atmosphere using standard Schlenk techniques in oven-dried glassware. Tetrahydrofuran and.

  7. Tuning of intermolecular interactions results in packing diversity in ...

    Indian Academy of Sciences (India)

    Crystal structures of four green fluorescent protein (GFP) chromophore analogues with different packing interactions could be tuned by appropriate substitutions around the imidazolin-5-one ring are reported here. Compound 1 was crystallized from tetrahydrofuran at room temperature while compounds 2-4 have been ...

  8. Coronin from roots of Annona muricata, a putative intermediate in acetogenin biosynthesis (1).

    Science.gov (United States)

    Gleye, C; Akendengue, B; Laurens, A; Hocquemiller, R

    2001-08-01

    A novel acetogenin, coronin, was isolated from the roots of Annona muricata L. The structure was elucidated by a combination of chemical and spectral methods including MS and NMR measurements. Coronin is probably an intermediate in the biosynthetic pathway of bis-tetrahydrofuran acetogenins, and is proposed as a biogenetic precursor of neoannonin-B.

  9. Assessment of the Larvicidal potentials of Thymol derivatives on ...

    African Journals Online (AJOL)

    DR. MIKE HORSFALL

    -methyl ether (2): 15mls (0.08 moles) of an ethereal solution of diazomethane was added to a solution of 1g (0.07 moles) thymol (1) in 4mls dry tetrahydrofuran (THF) and stirred for 16 hours at room temperature. The solvent was evaporated off.

  10. Crystallization-induced red emission of a facilely synthesized biodegradable indigo derivative.

    Science.gov (United States)

    Yang, Cangjie; Trinh, Quang Thang; Wang, Xiaochen; Tang, Yuxin; Wang, Kai; Huang, Shuo; Chen, Xiaodong; Mushrif, Samir H; Wang, Mingfeng

    2015-02-25

    We report a new class of crystallization-induced red-emitting luminogen based on a synthetic biodegradable indigo derivative, Indigoid-B. This compound, upon an ultrasonic treatment, formed well-defined microcrystals that showed striking crystallization-induced emission (CIE) in mixed solvents of tetrahydrofuran-water.

  11. DFT-based inhibitor and promoter selection criteria for pentagonal ...

    Indian Academy of Sciences (India)

    Methane hydrate formation inhibition by methanol and ethylene glycol as well as methane hydrate stabilization by cyclopentane and tetrahydrofuran are critically analysed based on the interaction energy, free energy change, dipole moment and infrared frequency calculation. Calculation of free energy change for formation ...

  12. Nano copper ferrite: A reusable catalyst for the synthesis of , ...

    Indian Academy of Sciences (India)

    Copper ferrite nano material as reusable heterogeneous initiator in the synthesis of , -unsaturated ketones and allylation to acid chlorides are presented. The reaction of allylichalides with various acid chlorides is achieved in the presence of copper ferrite nano powders at room temperature in tetrahydrofuran (THF).

  13. Synthesis of fluorescent diblock copolymer nanoparticle supported ...

    Indian Academy of Sciences (India)

    ROP of caprolactonewas carried out at 160 ∘ C for 2 h under nitrogen atmosphere in the presence of stannous octoate (Sn(Oct) 2 ) as a catalyst followed by the ROP of tetrahydrofuran in the presence of phthalicanhydride as a co-monomer. Thus, synthesized fluorescent DBCNC was characterized by various analytical tools ...

  14. Synthesis and characterization of poly(2-ethylhexyl acrylate ...

    Indian Academy of Sciences (India)

    (Aldrich), tetrahydrofuran (THF) (Merck) and acetone. (Merck) were used as received. BPO (Merck) was purified by recrystallizing from acetone. 2.2 Polymerization. 2.2a Homo polymerization of EHA: ATRP of EHA was carried out in bulk. In a typical bulk polymeriza- tion, the catalyst CuCl (0.0118g, 0.12mmol) and the.

  15. Encapsulated PDMS microspheres with reactive handles

    DEFF Research Database (Denmark)

    Gonzalez, Lidia; Ma, Baoguang; Li, Li

    2014-01-01

    , cured PDMS microspheres are coated with poly(methyl methacrylate) using a chemical process (solvent evaporation technique). Three solvents are used in three different experiments: dichloromethane, tetrahydrofuran, and acetone. The composition and morphology of the cured PDMS microspheres and PMMA coated...

  16. Dipeptide synthesis in near-anhydrous organic media: Long-term stability and reusability of immobilized Alcalase

    NARCIS (Netherlands)

    Vossenberg, P.; Beeftink, H.H.; Nuijens, T.; Quaedflieg, P.J.L.M.; Cohen Stuart, M.A.; Tramper, J.

    2013-01-01

    The long-term stability and re-use of Alcalase covalently immobilized onto macroporous acrylic beads (Cov) in tetrahydrofuran (THF) were investigated. Cov can be used to synthesize dipeptides under near-anhydrous conditions in THF. Cov was incubated with and without molecular sieves (beads or

  17. Effect of chain length on the adhesion behaviour of n-alkanethiol self ...

    Indian Academy of Sciences (India)

    CH2)nSH (n = 5, 6, 7, 9, 10,. 11, 14 and 15) were purchased from Aldrich, USA and used as-received. AR grade tetrahydrofuran (Ranbaxy, India) and absolute ethanol (AR grade, Les alcools de. 754. Pramana – J. Phys., Vol. 65, No. 4, October ...

  18. Photoelectronic properties of HgI 2 crystals for nuclear radiation ...

    Indian Academy of Sciences (India)

    Photoelectronic properties of red mercuric iodide single crystals, grown from its saturated solution in tetrahydrofuran, have been studied for the wavelength range 450-700 nm at temperatures 80, 110, 175, 235 and 300 K. Various aspects of the optical generation of charge carriers have been discussed. The computer ...

  19. 40 CFR Appendix A to Part 439 - Tables

    Science.gov (United States)

    2010-07-01

    ... Chloroform 1 Chlorinated Alkanes. Methylene chloride 1 1,2-Dichloroethane 1 Ethyl acetate 1 Esters. Isopropyl acetate n-Amyl acetate n-Butyl acetate Methyl formate Tetrahydrofuran 1 Ethers. Isopropyl ether Acetone 1...-Amyl acetate n-Butyl acetate Ethyl acetate Medium strippability. Isopropyl acetate Methyl formate...

  20. Treatments of intrinsic viscosity and glass transition temperature data of poly(2,6-dimethylphenylmethacrylate)

    Energy Technology Data Exchange (ETDEWEB)

    Hamidi, Nasrollah; Massoudi, Ruhullah

    2003-03-05

    A useful relationship, ln(T{sub g})=ln(T{sub g,{infinity}})-m[{eta}]{sup -{nu}}, between intrinsic viscosity and glass transition temperature for a series of homologous polymers was obtained by combining the Mark-Houwink-Kuhn-Sakurada (MHKS) relation for intrinsic viscosity and molecular mass, and the Fox-Flory equation for glass transition temperature and number-average molecular mass. This relationship was applied to poly(2,6-dimethylphenylmethacrylate) (PDMPh) in a variety of solvents (ideal to good) such as toluene, tetrahydrofuran/water, tetrahydrofuran, and chlorobenzene systems. The parameter {alpha} estimated by this procedure in toluene, tetrahydrofuran/water, tetrahydrofuran, and chlorobenzene systems are 0.50{sub 6}, 0.51{sub 1}, 0.56{sub 7}, and 0.67{sub 3}, respectively which are in agreement with those of Mark-Houwink-Kuhn-Sakurada values by less than 5% differences. The T{sub g,{infinity}} quantity estimated from this equation also is within the standard deviation of that obtained from the Fox-Flory method. The m quantity is increasing as the thermodynamic quality of the solvent improves, therefore, m may be considered as an indicator of coil conformations in a given solvent.

  1. Low-Cost and High-Impact Environmental Solutions for Military Composite Structures

    Science.gov (United States)

    2005-12-15

    thermal gravimetric analysis THF tetrahydrofuran UHC unburned hydrocarbons UP UPE unsaturated polyester UV VARTM vacuum assisted resin...was established. Traditional methods of volatiles analysis involve thermal gravimetric analysis (TGA) and desorption gas chromatography-mass...manner relative to biodiesel . The cost of biodiesel is ~ $2/gallon or $0.30/lb. Considering the inexpensive chemicals and similar purification

  2. Viscosities of oxalic acid and its salts in water and binary aqueous ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Relative viscosities for the solutions of oxalic acid and its salts, viz. ammonium oxalate, sodium oxalate and potassium oxalate, at different concentrations have been determined in water and in binary aqueous mixtures of tetrahydrofuran (THF) [5, 10, 15 and 20% by weight of THF] at 298⋅15 K, and in water and in ...

  3. Cross-coupling of nonactivated alkyl halides with alkynyl Grignard reagents: a nickel pincer complex as the catalyst.

    OpenAIRE

    Vechorkin Oleg; Godinat Aurélien; Scopelliti Rosario; Hu Xile

    2011-01-01

    The nickel pincer complex 1 catalyzes the cross coupling of the title compounds with remarkable substrate scope and functional group tolerance. A nickel/alkynyl species was isolated and shown to be catalytically competent. THF=tetrahydrofuran O TMEDA=bis[2 (NN dimethylaminoethyl)] ether.

  4. Effect of silver nanoparticle on the properties of poly (methyl ...

    Indian Academy of Sciences (India)

    Photopolymerization was performed in the presence of allyl methacrylate, as crosslinking agent, and various amount of silver nanoparticles (AgNPs). AgNPs were synthesized via chemical reduction of silver nitrate with t-BuONa-activated sodium hydride in tetrahydrofuran. The degree of monomer conversion (DC%) during ...

  5. Self-Assembly, Guest Capture, and NMR Spectroscopy of a Metal-Organic Cage in Water

    Science.gov (United States)

    Go, Eun Bin; Srisuknimit, Veerasak; Cheng, Stephanie L.; Vosburg, David A.

    2016-01-01

    A green organic-inorganic laboratory experiment has been developed in which students prepare a self-assembling iron cage in D[subscript 2]O at room temperature. The tetrahedral cage captures a small, neutral molecule such as cyclohexane or tetrahydrofuran. [Superscript 1]H NMR analysis distinguishes captured and free guests through diagnostic…

  6. Synthesis and Antimicrobial Activity of 3-[(4-Substituted) (2-oxo-1,3 ...

    African Journals Online (AJOL)

    Bis-(2-oxo-1,3-oxazolidin-3-yl)-phosphonic chloride (2) prepared by the reaction of two moles of oxazolidin-2-one (1) with phosphorus oxychloride in dry tetrahydrofuran in the presence of triethylamine and treatment with various heterocyclic aromatic and aliphatic amines under the same experimental conditions afforded ...

  7. Coal anion structure and chemistry of coal alkylation. Final report, March 1, 1979-February 29, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Stock, L.M.

    1980-01-01

    In accord with Task 1, some ether cleavage reactions were carried out in two different media - potassium/naphthalene/tetrahydrofuran and potassium/ ammonia - so that the merits and demerits of the two methods could be compared. Preliminary results suggest that both systems yield the same products, and that the ammonia medium is more convenient to work with, because of the absence of by-products such as reduced naphthalenes and tetralin. Dialkyl ethers were found to be least reactive compounds while the benzyl and phenyl ethers were found to be most reactive, as would be expected. The reductive alkylation of coal was carried out in ammonia at 25/sup 0/C. The tetrahydrofuran solubility of the reaction product was surprisingly low. We have obtained additional /sup 13/C)/sup 1/H) nmr data for tetrahydrofuran-soluble butylated coal and some model compounds; obtained additional Styragel(R) chromatography data of tetrahydrofuran-soluble coal labelled with 98%-enriched butyl-1,1-d/sub 2/ iodide; and obtained /sup 2/D nmr spectra of all the deuterium-labelled, tetrahydrofuran-soluble coal products. In accord with Task 4, we have undertaken a review of the information now available concerning the nature of Illinois No. 6 coal. Also, the effects of organic additives on the exchange reactions between tetralin-d/sub 12/ and diphenyl-methane and on the thermal cleavage reactions of several model compounds in tetralin were investigated to probe the relationship between structure and reactivity. The exchange reaction can be accelerated by coal, asphaltene-preasphaltene fractions derived from coal, compounds with labile bonds, or compounds which can be reduced readily. The pyridine-insoluble coal product, acids, and bases are inactive toward the exchange reaction.

  8. Electrospun cellulose acetate phthalate nanofibrous scaffolds fabricated using novel solvent combinations biocompatible for primary chondrocytes and neurons.

    Science.gov (United States)

    Shrestha, Rupendra; Palat, Asha; Punnoose, Alan M; Joshi, Shailesh; Ponraju, D; Paul, Solomon F D

    2016-12-01

    Electrospun nanofibres have been shown to exhibit extracellular matrix (ECM)-like characteristics required for tissue engineering in terms of porosity, flexibility, fibre organization and strength. This study focuses on developing novel cellulose acetate phthalate (CAP) scaffolds by electrospinning for establishing 3-D chondrocyte and neuronal cultures. Five solvent combinations were employed in fabricating the fibres, namely, acetone/ethanol (9:1), dimethylformamide/tetrahydrofuran/acetone (3:3:4), tetrahydrofuran/acetone (1:1), tetrahydrofuran/ethanol (1:1) and chloroform/methanol (1:1). The electrospun fibres were characterized by scanning electron microscopy (SEM) analysis and confirmed to be within the nanometre range. Based on the morphology of the fibers from SEM results, two solvent combinations such as acetone/ethanol and dimethylformamide/tetrahydrofuran/acetone were selected for stabilization as CAP exhibits a pH dependent solubility. Fourier-Transform Infrared (FTIR) analysis revealed the hydrolysis of CAP which was overcome by EDC [1-ethyl-3-(3-dimethylaminopropyl) carbodiimide] and EDC/NHS (N-hydroxysuccinimide) cross-linking resulting in its stability (pH of 7.2) for three months. MTT [3-(4, 5-dimethylthiazol-2-yl)-1, 5-diphenyltetrazolium bromide] assay performed using L6 myoblast confirmed the biocompatibility of the scaffolds. 3-D primary chondrocyte and neuronal cultures were established on the scaffolds and maintained for a period of 10 days. H&E staining and SEM analysis showed the attachment of the chondrocytes and neurons on CAP scaffolds prepared using dimethylformamide/tetrahydrofuran/acetone and acetone/ethanol respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Solution small-angle x-ray scattering as a screening and predictive tool in the fabrication of asymmetric block copolymer membranes

    KAUST Repository

    Dorin, Rachel Mika

    2012-05-15

    Small-angle X-ray scattering (SAXS) analysis of the diblock copolymer poly(styrene-b-(4-vinyl)pyridine) in a ternary solvent system of 1,4-dioxane, tetrahydrofuran, and N,N-dimethylformamide, and the triblock terpolymer poly(isoprene-b-styrene-b-(4-vinyl)-pyridine) in a binary solvent system of 1,4-dioxane and tetrahydrofuran, reveals a concentration-dependent onset of ordered structure formation. Asymmetric membranes fabricated from casting solutions with polymer concentrations at or slightly below this ordering concentration possess selective layers with the desired nanostructure. In addition to rapidly screening possible polymer solution concentrations, solution SAXS analysis also predicts hexagonal and square pore lattices of the final membrane surface structure. These results suggest solution SAXS as a powerful tool for screening casting solution concentrations and predicting surface structure in the fabrication of asymmetric ultrafiltration membranes from self-assembled block copolymers. (Figure presented) © 2012 American Chemical Society.

  10. Biological activities of lignoids from Amazon Myristicaceae species: Virota michelii, V. mollissima, V. pavonis and Iryanthera juruensis

    Energy Technology Data Exchange (ETDEWEB)

    Morais, Sabrina K.R.; Yoshida, Massayoshi [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica; Centro de Biotecnologia da Amazonia, Manaus, AM (Brazil)], e-mail: myoshida@iq.usp.br; Teixeira, Ana F. [Universidade do Estado do Amazonas, Manaus, AM (Brazil). Escola Normal Superior; Torres, Zelina E. dos S. [Universidade do Estado do Amazonas, Manaus, AM (Brazil). Escola Superior de Ciencias da Saude; Numomura, Sergio M. [Instituto Nacional de Pesquisas da Amazonia (INPA), Manaus, AM (Brazil). Coordenacao de Pesquisa de Produtos Naturais; Yamashiro-Kanashiro, Edite H.; Lindoso, Jose Angelo I. [Universidade de Sao Paulo, SP (Brazil). Hospital das Clinicas. Lab. de Epidemiologia e Imunobiologia

    2009-07-01

    This work revisits the fruits of Iryanthera juruensis and Virola pavonis and the leaves from V. michelii, as well as describing a study of the fruits of V. mollissima. In I. juruensis aryltetraline neolignan (1) and tetrahydrofuran neolignan (2), were found while from V. pavonis neolignans of benzofuran type (6-9), the tetrahydrofuran type (2, 11-13, 17) and the biphenyl type (10), in addition to diastereoisomers of the 8.O.4'-oxyneolignan type (14 and 15) and others were isolated. The V. mollissima accumulates the aryltetralone neolignan 4 and its seco derivative (5). The lignoids 1 and 2 obtained from I. juruensis arils possess antileishmanial activity against the promastigote form of Leishmania amazonensis. (author)

  11. Methyl (9aR*,10S*,11R*,13aS*,13bS*-9-oxo-6,7,9,9a,10,11-hexahydro-5H,13bH-11,13a-epoxypyrrolo[2′,1′:3,4][1,4]diazepino[2,1-a]isoindole-10-carboxylate

    Directory of Open Access Journals (Sweden)

    Flavien A. A. Toze

    2011-11-01

    Full Text Available The title compound, C17H18N2O4, is the methyl ester of the adduct of intramolecular Diels–Alder reaction between maleic anhydride and 1-(2-furyl-2,3,4,5-tetrahydro-1H-pyrrolo[1,2-a][1,4]diazepine. The molecule comprises a fused pentacyclic system containing four five-membered rings (viz. pyrrole, 2-pyrrolidinone, tetrahydrofuran and dihydrofuran and one seven-membered ring (1,4-diazepane. The pyrrole ring is approximately planar (r.m.s. deviation = 0.003 Å while the 2-pyrrolidinone, tetrahydrofuran and dihydrofuran five-membered rings have the usual envelope conformations. The central seven-membered diazepane ring adopts a boat conformation. In the crystal, molecules are bound by weak intermolecular C—H...O hydrogen-bonding interactions into zigzag chains propagating in [010]. In the crystal packing, the chains are stacked along the a axis.

  12. Influência de diferentes solventes utilizados na deposição de filme de poli(9-vinilcarbazol em dispositivos OLEDs

    Directory of Open Access Journals (Sweden)

    Emerson Roberto Santos

    2014-01-01

    Full Text Available This work studies the influence of the film deposition process on light emission performance and on threshold voltage of OLEDs, with architecture glass/ITO/PEDOT:PSS/PVK/Alq3/Al. The commercial PVK was dissolved in different solvents such as: chloroform, tetrahydrofuran, 1,2,4-trichlorobenzene and trimethylpentane. OLEDs were characterized by current-voltage and revealed a significant influence of the solvents, although all devices emitted green electroluminescence. A difference in threshold voltage up to 10 V was observed among OLEDs prepared from different solvents. The 1,2,4-trichlorobenzene showed best performance, presenting lowest treshold voltage (≈ 6 V, followed by tetrahydrofuran (≈ 8 V, trimethylpentane (≈ 14 V and chloroform (≈ 16 V.

  13. Thermal stability and structural characteristics of PTHF–Mmt organophile nanocomposite

    Directory of Open Access Journals (Sweden)

    Youcef Hattab

    2015-05-01

    The objective of this study is to use organophilized montmorillonites in the presence of monomer tetrahydrofuran to obtain polytétrahydrofuran montmorillonites (PTHF–Mmt of composites by polymerization in situ. The organophilisation of the Mmt is formed by active cationic surface. The obtained results show an increase in the distance inside the reticular in the diffractograms of X-rays (DRX and the appearance of absorption bands of the characteristics of polytétrahydrofuran on the spectra of infrared spectroscopy (IR, which indicate pre-polymerization of tetrahydrofuran in the galleries of clay and, therefore, the obtaining of a nanocomposite. We have also studied the thermal stability of the samples by differential analysis calorimetric (DSC analysis, and we can conclude that the nanocomposites are stabilized thermally by the presence of clay in the matrix.

  14. 5-(4-Bromophenyl-1,2,3,4-tetrahydrobenzo[a]phenanthridine

    Directory of Open Access Journals (Sweden)

    Ling Su

    2009-05-01

    Full Text Available The title compound, C23H18BrN, was synthesized by the reaction of 4-bromobenzaldehyde, naphthalen-2-amine and cyclohexanone in tetrahydrofuran, catalyzed by iodine. The saturated six-membered ring adopts a half-chair conformation, and the four vicinal rings form a helical conformation, which results in a significant deviation from planarity for the pyridine ring. In the crystal, a weak C—H...π interaction occurs, leading to inversion dimers.

  15. Electrochemical selenium- and iodonium-initiated cyclisation of hydroxy-functionalised 1,4-dienes

    Directory of Open Access Journals (Sweden)

    Philipp Röse

    2015-01-01

    Full Text Available The cobalt(I-catalysed 1,4-hydrovinylation reaction of allyloxytrimethylsilane and allyl alcohol with substituted 1,3-dienes leads to hydroxy-functionalised 1,4-dienes in excellent regio- and diastereoselective fashion. Those 1,4-dienols can be converted into tetrahydrofuran and pyran derivatives under indirect electrochemical conditions generating selenium or iodonium cations. The reactions proceed in good yields and regioselectivities for the formation of single diastereomers.

  16. Pinoresinol from Ipomoea cairica cell cultures.

    Science.gov (United States)

    Páska, Csilla; Innocenti, Gabbriella; Ferlin, Mariagrazia; Kunvári, Mónika; László, Miklós

    2002-10-01

    Ipomoea cairica cell cultures produced a tetrahydrofuran lignan, (+)-pinoresinol, identified by UV, IR, MS and NMR methods, not yet found in the intact plant, and new in the Convolvulaceae family. Pinoresinol was found to have antioxidant and Ca2+ antagonist properties. As it could be requested for its biological activity, we examined the possibility to raise the pinoresinol yield of I. cairica cultures, as well as we continued investigations on lignans' response to optimization.

  17. Materials Research Center, University of Pittsburgh

    Science.gov (United States)

    1994-04-29

    enzyme in tetrahydrofuran (THF), following the catalysis of transesterification rather thanI hydrolysis. The kinetic constants for the methanolysis of...Baillargeon, M.W., Sonnet, P.E. 1988. Lipase modified for solubility in organic solvents. Ann. N.Y. Acad. Sci. 542: 244-249. 2. Chatterjee, S., Russell... transesterification in anhydrous environments. Ayala, G.A., Kamat, S., Komives, C., Beckman, E.J. and Russell, A.J. (1992)I Annals New York Acad. Sci

  18. Enhancement of the thermo-mechanical properties and efficacy of mixing technique in the preparation of graphene/PVC nanocomposites compared to carbon nanotubes/PVC

    OpenAIRE

    Hasan, Mudassir; Lee, Moonyong

    2014-01-01

    Thin films of poly vinyl chloride (PVC)/multiwalled carbon nanotubes (MWCNT) and PVC/graphene (GN) nanocomposites were prepared by mixing in the presence of different quantities of nanoparticles. Film casting was performed using tetrahydrofuran as a solvent. The as-prepared PVC/MWCNT and PVC/GN nanocomposites were characterized by scanning electron microscopy, Raman spectroscopy, X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and...

  19. Inferences regarding the nature of solvent-refined coal (SRC)

    Energy Technology Data Exchange (ETDEWEB)

    Wooton, D.L.; Dorn, H.C.; Taylor, L.T.; Coleman, W.M.

    1976-07-01

    Solvent-refined coal product has been subjected to numerous analytical techniques in an effort to ascertain its chemical nature. Electron spin resonance, /sup 13/C and /sup 1/H nuclear magnetic resonance, and mass spectroscopy along with elemental and molecular weight analyses have been employed. High-performance liquid chromatography via gel permeation separates tetrahydrofuran-soluble SRC into several size fractions. Nuclear magnetic resonance data strongly suggest that hexamethylphosphoramide-soluble SRC is approximately 95 percent aromatic in character.

  20. Chemical synthesis of benzamide riboside.

    Science.gov (United States)

    Krohn, K; Dörner, H; Zukowski, M

    2002-04-01

    The C-glycosidic nicotinamide riboside analogue (1) was prepared by reaction of ribonolactone 16 with the lithiated 2-oxazoline 13 followed by triethylsilane reduction of the hemiacetal 17 to the tetrahydrofurane 18. Cleavage of the oxazoline group in 20 to the acid 21, conversion of the acid chloride 22 to the amide 23, and hydrogenative debenzylation afforded the benzamide riboside 1. Phosphorylation of the acetonide 26 and acid-catalyzed cleavage of the resulting ketal yielded the pseudonucleotide 27.

  1. Biomimetic asymmetric total syntheses of spirooliganones A and B.

    Science.gov (United States)

    Song, Liyan; Yao, Hongliang; Tong, Rongbiao

    2014-07-18

    Biomimetic total syntheses of potent antiviral spirooliganones A and B were achieved with 3% and 2% yield, respectively, in 12 steps from commercially available materials. The synthetic strategy was inspired primarily by the biogenetic hypothesis and was enabled by two independent cascade events: (i) an unprecedented reaction involving aromatic Claisen rearrangement/o-quinone methide formation/hetero-Diels-Alder cycloaddition to construct the tetracyclic framework and (ii) phenol oxidative dearomatization/spirocyclization to build the spiro-fused cyclohexadienone/tetrahydrofuran moiety.

  2. Methyl 4,5-diacetoxy-1-oxo-2-phenylperhydro-4,6-epoxycyclopenta[c]pyridine-7-carboxylate ethanol solvate

    Directory of Open Access Journals (Sweden)

    Victor N. Khrustalev

    2009-12-01

    Full Text Available The title compound, the product of an acid-catalysed Wagner–Meerwein skeletal rearrangement, crystallizes as an ethanol monosolvate, C20H21NO8·C2H6O. The title molecule comprises a fused tricyclic system containing two five-membered rings (cyclopentane and tetrahydrofuran in the usual envelope conformations and one six-membered ring (piperidinone adopting a flattened twist–boat conformation.

  3. Lipase-catalysed selective deacetylation of phenolic/enolic acetoxy groups in peracetylated benzyl phenyl ketones.

    Science.gov (United States)

    Parmar, V S; Pati, H N; Azim, A; Kumar, R; Himanshu; Bisht, K S; Prasad, A K; Errington, W

    1998-01-01

    Highly chemo- and regioselective de-esterification has been observed in the deacetylation of peracetylated enolic forms of polyphenolic benzyl phenyl ketones by lipase from porcine pancreas (PPL) suspended in tetrahydrofuran (THF). The enzyme selectively deacetylates the enolic acetoxy over the phenolic acetoxy group(s) and continuation of the reaction resulted, in addition the regioselective deacetylation of acetoxy function para to the nuclear carbonyl group.

  4. CHROMIUM(II) AMIDES - SYNTHESIS AND STRUCTURES

    NARCIS (Netherlands)

    EDEMA, JJH; GAMBAROTTA, S; MEETSMA, A; SPEK, AL; SMEETS, WJJ; CHIANG, MY

    1993-01-01

    A novel class of mono- and di-meric chromium(II) amides has been prepared and characterized. Reaction of [CrCl2(thf)2] (thf = tetrahydrofuran) with 2 equivalents of M(NR2) (R = C6H11, Pr(i), Ph, or phenothiazinyl; M = Li or Na) allowed the formation of the homoleptic amides [{Cr(mu-NR2)(NR2)}2] (R =

  5. USAF Summer Research Program - 1994 Summer Faculty Research Program, Final Reports, Volume 5A, Wright Laboratory

    Science.gov (United States)

    1994-12-01

    pp. 569-578 (1986). (b) Turchi, C. S.; Ollis, D. F. " Photocatalytic Degradation of Organic Water Contaminants: Mechanisms Involving Hydroxyl Radical...brominated-fluorene solution 9, the mixture turned a clear yellow- orange color. However once the ice bath was removed, the solution turned black. It is...tetrahydrothiophene (THS), and 2- methyl tetrahydrofuran (2MTHF) are summarized in Table I. In addition, MOPAC 6 (AMI and PM3) parameters (obtained from

  6. Hitorins A and B, Hexacyclic C25 Terpenoids from Chloranthus japonicus.

    Science.gov (United States)

    Kim, Sang-Yong; Nagashima, Hisako; Tanaka, Naonobu; Kashiwada, Yoshiki; Kobayashi, Jun'ichi; Kojoma, Mareshige

    2016-10-10

    Two novel C25 terpenoids with a 6/5/5/5/5/3 hexacyclic skeleton including one γ-lactone ring and two tetrahydrofuran rings, hitorins A (1) and B (2), were isolated from the aerial parts of Chloranthus japonicus. The structures of 1 and 2 were elucidated on the basis of spectroscopic analyses as well as TDDFT ECD calculations. Hitorins A (1) and B (2) might be biogenetically derived from eudesmane sesquiterpene and thujane monoterpene.

  7. Identification of an Unexpected 2-Oxonia[3,3]sigmatropic Rearrangement/Aldol Pathway in the Formation of Oxacyclic Rings. Total Synthesis of (+)-Aspergillin PZ

    OpenAIRE

    Canham, Stephen M.; Overman, Larry E.; Tanis, Paul S.

    2011-01-01

    This paper reports the first unambiguous evidence that the cascade synthesis of tetrahydrofuran-containing oxacyclic molecules depicted in Scheme 12 can take place by a 2-oxonia[3,3]sigmatropic/aldol mechanism rather than by a Prins cyclization/pinacol rearrangement sequence. The 8-oxabicyclo[3.2.1]octyl aldehyde products of this reaction, 20 and 29, were employed to complete the first total synthesis of the structurally remarkable isoindolone alkaloid (+)-aspergillin PZ (1). The lack of acti...

  8. Preparation and characterization of aliphatic diphenyl esters intended as precursors for polyesters

    DEFF Research Database (Denmark)

    Hvilsted, S.; Andruzzi, F.; Cerrai, P.

    1991-01-01

    based on similar data from phenyl esters, interpreted as the results of an apparent macrocyclic conformation of the larger diphenyl esters. High-performance size exclusion chromatography (s.e.c.) of diphenyl esters, phenyl esters, aromatic and linear hydrocarbons in tetrahydrofuran, toluene...... and chloroform points to specific phenyl ester-solvent interactions, which obscure a potential s.e.c. conformational analysis of the diphenyl esters....

  9. Lycopene enrichment of cultured airway epithelial cells decreases the inflammation induced by rhinovirus infection and lipopolysaccharide.

    Science.gov (United States)

    Saedisomeolia, Ahmad; Wood, Lisa G; Garg, Manohar L; Gibson, Peter G; Wark, Peter A B

    2009-08-01

    Rhinovirus infection results in increased release of inflammatory mediators from airway epithelial cells in asthma. As an antioxidant, lycopene offers protection from adverse effects of inflammation. The aim of this study was to find an appropriate method of lycopene enrichment of airway epithelial cells and to determine the effects of lycopene enrichment on the inflammatory response of cells infected by rhinovirus or exposed to lipopolysaccharide. Lycopene enrichment of airway epithelial cells using solubilisation in tetrahydrofuran versus incorporation in liposomes was compared. After determining that solubilisation of lycopene in tetrahydrofuran was the most suitable method of lycopene supplementation, airway epithelial cells (Calu-3) were incubated with lycopene (dissolved in tetrahydrofuran) for 24 h, followed by rhinovirus infection or lipopolysaccharide exposure for 48 h. The release of interleukin-6, interleukin-8 and interferon-gamma induced protein-10 (IP-10) and their messenger RNA levels were measured using enzyme linked immunosorbent assay and reverse transcription polymerase chain reaction, respectively. Viral replication was measured by tissue culture infective dose of 50% assay. Lycopene concentration of cells and media were analysed using high-performance liquid chromatography. Preincubation of airway epithelial cells with lycopene (dissolved in tetrahydrofuran) delivered lycopene into the cells and resulted in a 24% reduction in interleukin-6 after rhinovirus-1B infection, 31% reduction in IP-10 after rhinovirus-43 infection and 85% reduction in rhinovirus-1B replication. Lycopene also decreased the release of IL-6 and IP-10 following exposure to lipopolysaccharide. We conclude that lycopene has a potential role in suppressing rhinovirus induced airway inflammation.

  10. Stereoselective total synthesis of the potent anti-asthmatic compound CMI-977 (LDP-977)

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Luiz Carlos; Farina, Lui Strambi; Ferreira, Marco Antonio Barbosa, E-mail: ldias@iqm.unicamp.br [Universidade de Campinas (UNICAMP), SP (Brazil). Instituto de Quimica

    2013-02-15

    A short and efficient stereoselective total synthesis of CMI-977 (LDP-977), a potent and orally active anti-asthmatic compound, was developed. The key steps involve a highly diastereoselective Mukaiyama oxidative cyclization, which provides the trans-THF (tetrahydrofuran) unit and a Seyferth-Gilbert homologation to construct the triple bond in the target molecule. The synthesis of the key chiral building block was performed using Jacobsen hydrolytic kinetic resolution. (author)

  11. Chemical cleaning agents and bonding to glass-fiber posts

    OpenAIRE

    Ana Paula Rodrigues Gonçalves; Aline de Oliveira Ogliari; Patrícia dos Santos Jardim; Rafael Ratto de Moraes

    2013-01-01

    The influence of chemical cleaning agents on the bond strength between resin cement and glass-fiber posts was investigated. The treatments included 10% hydrofluoric acid, 35% phosphoric acid, 50% hydrogen peroxide, acetone, dichloromethane, ethanol, isopropanol, and tetrahydrofuran. Flat glass-fiber epoxy substrates were exposed to the cleaners for 60 s. Resin cement cylinders were formed on the surfaces and tested in shear. All treatments provided increased bond strength compared to untreate...

  12. Hawaii Energy and Environmental Technologies (HEET) Initiative

    Science.gov (United States)

    2011-12-01

    of glucose by Saccharomyces cerevisiae , a well documented and appropriate model system for biocalorimetry (Yonsel et al, 2007). Anaerobic...I 200 i 100 I -40mg -20m§ Tima (Hours) Figure 3.11 Thermograms of the anaerobic fermentation of glucose by Saccharomyces cerevisia ...synthesize and maintain pure H2 hydrate make it impractical as a medium to store and transport fuel, certain hydrate promoters such as tetrahydrofuran

  13. Preparation and study of properties of dispersed graphene oxide

    Directory of Open Access Journals (Sweden)

    Evgeniya Seliverstova

    2015-09-01

    Full Text Available Ability of graphene oxide to form stable dispersion in organic solvents was studied in this work. As it was shown, sonication of graphene leads to the decreas of the particle size. Stability of prepared graphene dispersions was studied upon measurements of distribution of number of the particles via size and change of optical density of the solutions with time. It was found that graphene oxide forms a more stable dispersion in tetrahydrofuran and dimethylformamide than in chloroform and acetone.

  14. The Mark-Houwink-Sakurada Equation for the Viscosity of Atactic Polystyrene

    Science.gov (United States)

    Wagner, Herman L.

    1985-10-01

    In this review, the second in a series, the viscosity-molecular weight (Mark-Houwink-Sakurada) relationships have been critically evaluated for atactic polystyrene for a variety of solvents often used for viscosity measurements. These are benzene, toluene, 1,2,4-trichlorobenzene, tetrahydrofuran, o-dichlorobenzene, 2-butanone, and two theta solvents, cyclohexane and decalin. In addition, the Mark-Houwink-Sakurada parameters for several other solvents, not used as frequently, are provided.

  15. Aldonolactones as Chiral Synthons

    DEFF Research Database (Denmark)

    Lundt, Inge

    1997-01-01

    closure of brominated aldonolactones with unsaturation yields functionalized cyclopentanes regio- and stereospecifically. This results in the synthesis of optically pure carbasugars. Easy manipulation of the hydroxy groups in the cyclopentane-lactones obtained, gives access to other hydroxy...... as the sulfonylated, lactones are suitable starting materials for the preparation of hydroxylated and amino substituted pyrrolidines and piperidines, obtained by simple treatment with ammonia. Boiling in water transformed the activated lactones into hydroxylated tetrahydrofurans. Radical-initiated internal ring...

  16. Enantioselective synthesis of 2,3-disubstituted trans-2,3-dihydrobenzofurans using a Brønsted base/thiourea bifunctional catalyst.

    Science.gov (United States)

    Barrios Antúnez, Diego-Javier; Greenhalgh, Mark D; Fallan, Charlene; Slawin, Alexandra M Z; Smith, Andrew D

    2016-07-26

    The diastereo- and enantioselective synthesis of 2,3-disubstituted trans-2,3-dihydrobenzofuran derivatives (15 examples, up to 96 : 4 dr, 95 : 5 er) via intramolecular Michael addition has been developed using keto-enone substrates and a bifunctional tertiary amine-thiourea catalyst. This methodology was extended to include non-activated ketone pro-nucleophiles for the synthesis of 2,3-disubstituted indane and 3,4-disubstituted tetrahydrofuran derivatives.

  17. The effect of poly (lactic-co-glycolic) acid composition on the mechanical properties of electrospun fibrous mats

    DEFF Research Database (Denmark)

    Liu, Xiaoli; Aho, Johanna Maaria; Baldursdottir, Stefania G.

    2017-01-01

    The aim of this study was to investigate the influence of polymer molecular structure on the electrospinnability and mechanical properties of electrospun fibrous mats (EFMs). Polymers with similar molecular weight but different composition ratios (lactic acid (LA) and glycolic acid (GA)) were...... dissolved in binary mixtures of N,N-dimethylformamide (DMF) and tetrahydrofuran (THF). The intrinsic viscosity and rheological properties of polymer solutions were investigated prior to electrospinning. The morphology and mechanical properties of the resulting EFMs were characterized by scanning electron...

  18. Facilitated preparation of bioconjugatable zwitterionic quantum dots using dual-lipid encapsulation.

    Science.gov (United States)

    Shrake, Robert; Demillo, Violeta G; Ahmadiantehrani, Mojtaba; Zhu, Xiaoshan; Publicover, Nelson G; Hunter, Kenneth W

    2015-01-01

    Zwitterionic quantum dots prepared through incorporated zwitterionic ligands on quantum dot surfaces, are being paid significant attention in biomedical applications because of their excellent colloidal stability across a wide pH and ionic strength range, antifouling surface, good biocompatibility, etc. In this work, we report a dual-lipid encapsulation approach to prepare bioconjugatable zwitterionic quantum dots using amidosulfobetaine-16 lipids, dipalmitoyl-sn-glycero-3-phosphoethanolamine lipids with functional head groups, and CuInS2/ZnS quantum dots in a tetrahydrofuran/methanol/water solvent system with sonication. Amidosulfobetaine-16 is a zwitterionic lipid and dipalmitoyl-sn-glycero-3-phosphoethanolamine, with its functional head, provides bioconjugation capability. Under sonication, tetrahydrofuran/methanol containing amidosulfobetaine-16, dipalmitoyl-sn-glycero-3-phosphoethanolamine, and hydrophobic quantum dots are dispersed in water to form droplets. Highly water-soluble tetrahydrofuran/methanol in droplets is further displaced by water, which induces the lipid self-assembling on hydrophobic surface of quantum dots and thus forms water soluble zwitterionic quantum dots. The prepared zwitterionic quantum dots maintain colloidal stability in aqueous solutions with high salinity and over a wide pH range. They are also able to be conjugated with biomolecules for bioassay with minimal nonspecific binding. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Sol-Gel Titanium Dioxide Nanoparticles: Preparation and Structural Characterization

    Directory of Open Access Journals (Sweden)

    Oon Lee Kang

    2016-01-01

    Full Text Available Titanium dioxide (TiO2 nanoparticle was achieved in an alternative sol-gel route, as involved in 1 M acidic solution: HCl-tetrahydrofuran (HCl-THF, HNO3-tetrahydrofuran (HNO3-THF, and ClHNO2-tetrahydrofuran (ClHNO2-THF solution. Resultant TiO2 nanoparticle was further investigated in a systematic analytical approach. Nanoscale TiO2 structure was observed at a moderate hydrolysis ratio (8≤RH≤16. Particle size range was much narrower in an aprotic HNO3-THF medium, as compared to a differential HCl-THF medium. Biphasic TiO2 structure was detected at a certain hydrolysis ratio (RH≥16. Even so, relative anatase content was rather insignificant in an aprotic HCl-THF medium, as compared to a differential HNO3-THF medium. Tetragonal TiO2 structure was observed in the entire hydrolysis ratio (4≤RH≤32. Interstitial lattice defect was evident in an aprotic HNO3-THF medium but absent in a differential ClHNO2-THF medium.

  20. Water-soluble metal working fluids additives derived from the esters of acid anhydrides with higher alcohols for aluminum alloy materials.

    Science.gov (United States)

    Yamamoto, Syutaro; Tomoda, Hideyuki; Watanabe, Shoji

    2007-01-01

    Water-soluble metal working fluids are used for processing of aluminum alloy materials. This short article describes properties of new additives in water-soluble metal working fluids for aluminum alloy materials. Many half esters or diesters were prepared from the reactions of higher alcohols with acid anhydrides. Interestingly, diesters of PTMG (tetrahydrofuran oligomer, MW = 650 and 1000) and polybutylene oxide (MW = 650) with maleic anhydride and succinic anhydride showed both of an excellent anti-corrosion property for aluminum alloy and a good hard water tolerance. The industrial soluble type processing oils including these additives also showed anti-corrosion property and hard water tolerance.

  1. Biocatalytic Synthesis of Novel Partial Esters of a Bioactive Dihydroxy 4-Methylcoumarin by Rhizopus oryzae Lipase (ROL

    Directory of Open Access Journals (Sweden)

    Vinod Kumar

    2016-11-01

    Full Text Available Highly regioselective acylation has been observed in 7,8-dihydroxy-4-methylcoumarin (DHMC by the lipase from Rhizopus oryzae suspended in tetrahydrofuran (THF at 45 °C using six different acid anhydrides as acylating agents. The acylation occurred regioselectively at one of the two hydroxy groups of the coumarin moiety resulting in the formation of 8-acyloxy-7-hydroxy-4-methylcoumarins, which are important bioactive molecules for studying biotansformations in animals, and are otherwise very difficult to obtain by only chemical steps. Six monoacylated, monohydroxy 4-methylcoumarins have been biocatalytically synthesised and identified on the basis of their spectral data and X-ray crystal analysis.

  2. Highly stable red-emitting polymer dots for cellular imaging

    Science.gov (United States)

    Chelora, Jipsa; Zhang, Jinfeng; Chen, Rui; Thachoth Chandran, Hrisheekesh; Lee, Chun-Sing

    2017-07-01

    Polymer dots (Pdots) have emerged as a new type of fluorescent probe material for biomedical applications and have attracted great interest due to their excellent optical properties and biocompatability. In this work, we report on a red-emitting P3HT Pdot fluorescent probe for intracellular bioimaging. The as-prepared Pdot fluorescent probe exhibits good stability and has a large Stokes shift (121 nm) compared to molecules in tetrahydrofuran (THF). Furthermore, the probe shows low cytotoxicity, broad absorption spectrum, resistance against photodegradation, and good water dispersibility. These advantageous characteristics make P3HT Pdots a promising fluorescent probe material for bioimaging.

  3. The direct oxidative diene cyclization and related reactions in natural product synthesis

    Directory of Open Access Journals (Sweden)

    Juliane Adrian

    2016-09-01

    Full Text Available The direct oxidative cyclization of 1,5-dienes is a valuable synthetic method for the (diastereoselective preparation of substituted tetrahydrofurans. Closely related reactions start from 5,6-dihydroxy or 5-hydroxyalkenes to generate similar products in a mechanistically analogous manner. After a brief overview on the history of this group of transformations and a survey on mechanistic and stereochemical aspects, this review article provides a summary on applications in natural product synthesis. Moreover, current limitations and future directions in this area of chemistry are discussed.

  4. Synthesis of Conformationally North-Locked Pyrimidine Nucleosides Built on an Oxabicyclo[3.1.0]hexane Scaffold | Center for Cancer Research

    Science.gov (United States)

    Beginning with a known 3-oxabicyclo[3.1.0]-hexane scaffold, the relocation of the fused cyclopropane ring bond and the shifting of the oxygen atom to an alternative location engendered a new 2-oxabicyclo[3.1.0]hexane template that mimics more closely the tetrahydrofuran ring of conventional nucleosides. The synthesis of this new class of locked nucleosides involved a novel approach that required the isocyanate with a hydroxyl-protected scaffold as a pivotal intermediate that was obtained in 11 steps from a known dihydrofuran precursor.

  5. POLY(GLYCIDYL METHACRYLATE-DIVINYLBENZENE MONOLITHIC CAPILLARY AS A STATIONARY PHASE FOR THE REVERSED-PHASE CHROMATOGRAPHIC SEPARATION OF PROTEINS

    Directory of Open Access Journals (Sweden)

    Nurul Hidayat Aprilita

    2010-06-01

    Full Text Available Capillary column with monolithic stationary phase was prepared from silanized fused-silica capillary of 200 µm I.D. by in situ free radical polymerization of divinylbenzene with glycidy methacrylate in the presence of decanol and tetrahydrofuran as porogens.  The hydrodynamic and chromatographic properties of this monolith, such as backpressure at different flow-rate, pore size distribution, van Deemter plot and the effect of varying gradient-rate were investigated.  Poly(glycidyl methacrylate-divinylbenzene monolithic capillary has been used successfully for the reversed-phase chromatographic separation of proteins.   Keywords: monolithic stationary phase, poly(glycidyl methacrylate-divinylbenzene, proteins

  6. A stable aquo-complex of lithiated di-tert-butylfluorosilanol. Synthesis and crystal structure

    OpenAIRE

    Schütte, Steffen; Pieper, Ursula; Klingebiel, Uwe; Stalke, Dietmar

    1993-01-01

    It was possible by crystallizing the lithiated derivative of di-tert-butylfluorosilanol to isolate a stable aquo-complex of this tetrameric compound as the first hydrolysis product. An X-ray diffraction study has revealed the existence of ([R2Si(F)OLi]3·[R2Si(OH)OLi] ·THF·H2O (R = CMe3; THF = tetrahydrofuran). The mechanism of hydrolysis from [R2Si(F)OLi]4 to this aquo-complex is discussed. peerReviewed

  7. sup 1 H nuclear magnetic resonance studies of the reduction of paramagnetic iron(III) alkyl porphyrin complexes to diamagnetic iron(II) alkyl complexes

    Energy Technology Data Exchange (ETDEWEB)

    Balch, A.L.; Cornman, C.R.; Safari, N. (Univ. of California, Davis (United States)); Latos-Grazynski, L. (Univ. of Wroclaw (Poland))

    1990-09-01

    Reaction of (TPP)Fe{sup III}Cl in dichloromethane with LiHBEt{sub 3} yields (TPP)Fe{sup III}Et. Reduction of (TPP)Fe{sup III}R to ((TPP)Fe{sup II}R){sup {minus}} (R = n-propyl, ethyl) by either LiHBEt{sub 3} or KHB(i-Bu){sub 3} can be accomplished in benzene/tetrahydrofuran solution, where electron exchange between the iron(III) and iron(II) alkyls is rapid. ((TPP)Fe{sup II}R){sup {minus}} is diamagnetic and is reoxidized by dioxygen by (TPP)Fe{sup III}R.

  8. Method of synthesizing tungsten nanoparticles

    Science.gov (United States)

    Thoma, Steven G; Anderson, Travis M

    2013-02-12

    A method to synthesize tungsten nanoparticles has been developed that enables synthesis of nanometer-scale, monodisperse particles that can be stabilized only by tetrahydrofuran. The method can be used at room temperature, is scalable, and the product concentrated by standard means. Since no additives or stabilizing surfactants are required, this method is particularly well suited for producing tungsten nanoparticles for dispersion in polymers. If complete dispersion is achieved due to the size of the nanoparticles, then the optical properties of the polymer can be largely maintained.

  9. Trichloridobis(ethyldiphenylphosphine(tetrahydrofuranmolybdenum(III

    Directory of Open Access Journals (Sweden)

    Tomasz Kruczyński

    2010-07-01

    Full Text Available In the mononuclear title compound, [MoCl3(C4H8O(C14H15P2], obtained by the reaction of trichlorotris(tetrahydrofuranmolybdenum(III and ethyldiphenylphosphine in tetrahydrofuran (THF solution, the MoIII atom is six-coordinated by one O atom of a THF molecule, two P atoms from two ethyldiphenylphosphine ligands and three Cl atoms in a distorted octahedral geometry. The C atoms of the THF molecule are disordered over two positions in a 0.55 (2:0.45 (2 ratio.

  10. Zirconium(IV)- and hafnium(IV)-catalyzed highly enantioselective epoxidation of homoallylic and bishomoallylic alcohols.

    Science.gov (United States)

    Li, Zhi; Yamamoto, Hisashi

    2010-06-16

    In this report, zirconium(IV)- and hafnium(IV)-bishydroxamic acid complexes were utilized in the highly enantioselective epoxidation of homoallylic alcohols and bishomoallylic alcohols, which used to be quite difficult substrates for other types of asymmetric epoxidation reactions. The performance of the catalyst was improved by adding polar additive and molecular sieves. For homoallylic alcohols, the reaction could provide epoxy alcohols in up to 83% yield and up to 98% ee, while, for bishomoallylic alcohols, up to 79% yield and 99% ee of epoxy alcohols rather than cyclized tetrahydrofuran compounds could be obtained in most cases.

  11. Origin and biochemical cycling of particulate nitrogen in the Mandovi estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, L.

    H 6.5) containing 3% of tetrahydrofuran as solvent A and methanol as solvent B was used to separate amino acids which were subsequently detected using a fluorescence detector (excitation λ=328 and emission λ=450 nm). The relative standard deviation... column (4.6 mm ID, 15 cm length, 5 mm particle size) was used to separated D-amino acids. A multi-step gradient system consisting of solvent A and B of 25 mM sodium acetate buffer at pH 7.0 and pH 5.3, respectively, and methanol as solvent C at flow...

  12. 9-{[4-(Dimethylaminobenzyl]amino}-5-(4-hydroxy-3,5-dimethoxyphenyl-5,5a,8a,9-tetrahydrofuro[3′,4′:6,7]naphtho[2,3-d][1,3]dioxol-6(8H-one methanol monosolvate

    Directory of Open Access Journals (Sweden)

    Hong Chen

    2011-11-01

    Full Text Available In the title compound, C30H32N2O7·CH4O, the tetrahydrofuran ring and the six-membered ring fused to it both display envelope conformations, with the ring C atom opposite the carbonyl group and the adjacent bridgehead C atom as the flaps, respectively. In the crystal structure, intermolecular O—H...O hydrogen bonds link all moieties into ribbons along [010]. Weak intermolecular C—H...O interactions consolidate the crystal packing further.

  13. Isolation of three new annonaceous acetogenins from Graviola fruit (Annona muricata) and their anti-proliferation on human prostate cancer cell PC-3.

    Science.gov (United States)

    Sun, Shi; Liu, Jingchun; Zhou, Ninghui; Zhu, Wenjun; Dou, Q Ping; Zhou, Kequan

    2016-09-01

    Bioassay-guided fractionation of the fruit powder of Graviola (Annona muricata) was continued to be conducted and yielded three more novel bioactive compounds: C-35 annonaceous acetogenins, muricins M and N, and C-37 annonaceous acetogenins, muricenin. They all contain a mono-tetrahydrofuran ring and four hydroxyl groups. The structures were elucidated by spectral methods and chemical modification after isolation via open column chromatographic separation and HPLC purification. Especially, murices M and N demonstrated more potent anti-proliferative activities against human prostate cancer PC-3 cells. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Alkyne- and alkyl-tris(cyclopentadienyl) complexes of uranium(III)

    Energy Technology Data Exchange (ETDEWEB)

    Foyentin, M.; Folcher, G.; Ephritkhine, M.

    1987-04-01

    Treatment of cp/sub 3/U(THF) (1) (cp=eta-C/sub 5/H/sub 5/, THF=tetrahydrofuran) with diphenylacetylene affords the alkyne complex cp/sub 3/U(Ph-C identical to C-Ph); (1) reacts with RLi (R = Me, Busup(n)) to give the alkyl compounds cp/sub 3/URLi (3); hydrogenolysis of (3) in the presence of a terminal alkene R'(-H) leads to the formation of cp/sub 3/UR'Li.

  15. N–H•••O hydrogen bonding. An FT-IR, NIR study of N-methylformamide–ether systems

    Directory of Open Access Journals (Sweden)

    BRANISLAV JOVIĆ

    2010-02-01

    Full Text Available This paper reports the results of an FT-IR and NIR study of N-methylformamide in carbon tetrachloride solution in presence of ethers as the O--electron donors, i.e., diethyl ether (DEE, diisopropyl ether (DiPE, methyl t--butyl ether (MtBE, dibutyl ether (DBE, dipentyl ether (DPE, tetrahydro-furan (THF and tetrahydropyran (THP. The spectroscopic characteristics of the N–H•••O hydrogen bonded complexes are given. In addition, the equilibrium constants for 1:1 complex formation were determined at 25 °C using Mid-IR and NIR measurements.

  16. 2007 International Brain Mapping and Intraoperative Surgical Planning Society’s (IBMISPS) Annual World Congress

    Science.gov (United States)

    2008-02-01

    0.15 mercury 0.01 0.08 methane 3000 2150 methanol 5 7 2-propanol 50 6 sulfur dioxide 1 3 tetrahydrofuran 40 118 1,1,1-trichloroethane 11 60 toluene 15 56...imaging of a sheep brain Accelerated imaging Magnetoencephalography Conclusions Introduction Magnetic resonance imaging (MRI) Magnetoencephalography...channels for Y=12 mm 3D imaging of a sheep brain Imaging parameters Pre-polarization time: tp = 0.5 s Encoding time: tg = 33 ms Acquisition time: tacq

  17. Star-shaped poly(2-(9-carbazolyl)methylthiirane): Synthesis, analysis and photoluminescencent properties

    Science.gov (United States)

    Swinarew, Andrzej; Stolarzewicz, Andrzej; Grobelny, Zbigniew; Swinarew, Beata; Grazulevicius, Juozas V.; Simokaitiene, Jurate; Andrikaityte, Egle

    2011-11-01

    The polymerization of 2-(9-carbazolyl)methylthiirane (CMT) in the presence of cyclic oligo(potassium glycidoxide) as the macroinitiator activated 18-crown-6 leads to star-shaped polythioether with a cyclic core and mainly six arms, and with molecular masses relatively near to the calculated ones. A particularly intensive blue photoluminescence is shown by poly(CMT) in tetrahydrofuran solution at the concentration equal to 2 × 10 -6 mol/dm 3. This polymer dispersed in commercially available transparent polymers, i.e. poly(methyl methacrylate), polycarbonate or polystyrene gives blue photoluminescent materials.

  18. "Hairy" Poly(3-hexylthiophene) Particles Prepared via Surface-Initiated Kumada Catalyst-Transfer Polycondensation

    DEFF Research Database (Denmark)

    Senkovskyy, Volodymyr; Tkachov, Roman; Beryozkina, Tetyana

    2009-01-01

    Herein, we present a new paradigm in the engineering of nanostructured hybrids between conjugated polymer and inorganic materials via a chain-growth surface-initiated Kumada catalyst-transfer polycondensation (SI-KCTP) from particles. Poly(3-hexylthiophene), P3HT, a benchmark material for organic...... to the untethered counterparts (red shift and vibronic fine structure in absorption and fluorescence spectra), as a result of efficient planarization and chain-aggregation. These effects are observed in solvents that are normally recognized as good solvents for P3HT (e.g., tetrahydrofurane). We attribute...

  19. Carbon dots with aggregation induced emission enhancement for visual permittivity detection.

    Science.gov (United States)

    Liu, Ze Xi; Wu, Zhu Lian; Gao, Ming Xuan; Liu, Hui; Huang, Cheng Zhi

    2016-02-04

    Photoluminescent carbon dots (CDs), hydrothermally prepared using tannic acid (TA), show visual aggregation induced emission enhancement (AIEE) properties at 455 nm when excited at 350 nm owing to the rotational hindering of the surface groups on CDs such as aromatic rings and phenolic hydroxyl ones, causing exponential decay between the ratio of the photoluminescence intensity in organic solvents to that in water and the permittivity of the solvent, and thus dazzling emissions of the CDs in the presence of solvents with small permittivity, tetrahydrofuran (THF), for instance, could be visually observed.

  20. Chemical transformations of neolignans

    Directory of Open Access Journals (Sweden)

    Massayoshi Yoshida

    1991-01-01

    Full Text Available Neolignans, generated by oxydative dimerization of propenylphenol and/or allylphenol, undergo further modifying steps. These biosynthetic reactions, confirmed in vitro, include Cope, retro-Claisen and Claisen rearrangements. Additionally acid catalysis effects convertions of bicyclo [3.2.1] octanoid neolignans into hydrobenzofuranoid neolignans, or inversely of hydrobenzofuranoid neolignans into bicyclo [3.2.1] octanoid neolignans, of hydrobenzofuranoid neolignans into futoenone type neolignans, of tetrahydrofuran neolignans into aryltetralin neolignans, as well as modifications by Friedel - Crafts reactions and the transformation of aryltetralin neolignans into arylindanones by pinacoline - pinacolone type rearrangement.

  1. Palladium-catalysed cyclisation of alkenols: Synthesis of oxaheterocycles as core intermediates of natural compounds

    Directory of Open Access Journals (Sweden)

    Miroslav Palík

    2014-09-01

    Full Text Available The study of Pd-catalysed cyclisation reactions of alkenols using different catalytic systems is reported. These transformations affect the stereoselective construction of mono- and/or bicyclic oxaheterocyclic derivatives depending on a starting alkenol. The substrate scope and proposed mechanism of Pd-catalysed cyclisation reactions are also discussed. Moreover, the diastereoselective Pd-catalysed cyclisation of appropriate alkenols to tetrahydrofurans and subsequent cyclisation provided properly substituted 2,5-dioxabicyclo[2.2.1]heptane and 2,6-dioxabicyclo[3.2.1]octane, respectively. Such bicyclic ring subunits are found in many natural products including ocellenynes and aurovertines.

  2. [Bis(TrimethylsilylMethyl]Lithium and -Sodium: Solubility in Alkanes and Complexes with O- and N- Donor Ligands

    Directory of Open Access Journals (Sweden)

    Markus von Pilgrim

    2017-06-01

    Full Text Available In contrast to alkyl compounds of lithium, which play an important role in organometallic chemistry, the corresponding heavier alkali metal compounds are less investigated. These compounds are mostly insoluble in inert solvents or undergo solvolysis in coordinating solvents due to their high reactivity. An exception from this typical behavior is demonstrated by bis(trimethylsilylmethylsodium. This study examines alkane solutions of bis(trimethylsilylmethyllithium and -sodium by NMR spectroscopic and cryoscopic methods. In addition, structural studies by X-ray crystallography of the corresponding compounds coordinated by O- and N- ligands (tetrahydrofuran and tetramethylethylenediamine present possible structural motifs of the uncoordinated compounds in solution.

  3. Development and Validation of New RP-HPLC Method for the Determination of Dexrazoxane

    OpenAIRE

    Basaveswara Rao, M. V.; Prasanthi, V.; Rao, G. Venkata; Raman, B. V.

    2012-01-01

    A new sensitive, precise, rapid and linear RP-HPLC method was developed and validated for the determination of dexrazoxane in formulations and human serum samples. Good chromatographic separation of dexrazoxane was achieved by using Kromasil C18 column. The system was operated at ambient temperature using a mobile phase consisting of methanol, 5% ortho phosphoric acid, 0.01M ammonium dihydrogen phosphate and tetrahydrofuran, pH 4.2 (10:40:30:20, v/v) isocratically at a flow rate of 1 ml/min. ...

  4. Synthesis of Substituted 2-Pyridyl-4-phenylquinolines

    Directory of Open Access Journals (Sweden)

    N. Cam Tat

    2002-08-01

    Full Text Available The acid-catalyzed condensation of o-aminobenzophenones with aromatic acetyl derivatives, in a basic methanol/tetrahydrofuran medium, has been used to prepare a series of substituted 2-pyridyl-4-phenylquinolines. Derivatives having two aza binding sites can act as asymmetric bidendate ligands to complex transition metals such as ruthenium, osmium or iridium. All the compounds were characterized by elemental analysis, Ei or FAB (+ MS, 1H- and 13C-NMR spectroscopies. Complete assignments of the 1H spectra were accomplished by using a combination of one- and two-dimensional NMR techniques.

  5. Stereoselective Synthesis of the C1-C9 and C11-C25 Fragments of Amphidinolides C, C2, C3, and F.

    Science.gov (United States)

    Akwaboah, Daniel C; Wu, Dimao; Forsyth, Craig J

    2017-03-03

    An efficient synthesis of the C1-C9 and the C11-C25 fragments of amphidinolides C, C2, C3, and F from a common intermediate is reported. The construction of the C1-C9 fragment involves an intramolecular hetero-Michael cyclization to form the 3,5-disubstituted trans-tetrahydrofuran moiety. The approach to prepare the C11-C25 fragment utilizes a highly stereoselective aerobic cobalt-catalyzed alkenol cyclization and a chelated Mukaiyama aldol reaction to form the C13-C14 bond and to concomitantly install the C13 hydroxyl group.

  6. Identification of an Unexpected 2-Oxonia[3,3]sigmatropic Rearrangement/Aldol Pathway in the Formation of Oxacyclic Rings. Total Synthesis of (+)-Aspergillin PZ.

    Science.gov (United States)

    Canham, Stephen M; Overman, Larry E; Tanis, Paul S

    2011-12-23

    This paper reports the first unambiguous evidence that the cascade synthesis of tetrahydrofuran-containing oxacyclic molecules depicted in Scheme 12 can take place by a 2-oxonia[3,3]sigmatropic/aldol mechanism rather than by a Prins cyclization/pinacol rearrangement sequence. The 8-oxabicyclo[3.2.1]octyl aldehyde products of this reaction, 20 and 29, were employed to complete the first total synthesis of the structurally remarkable isoindolone alkaloid (+)-aspergillin PZ (1). The lack of activity seen in two tumor cell lines for synthetic (+)-aspergillin PZ calls into question the suggestion that aspergillin PZ, like many aspochalasin diterpenes, might exhibit useful antitumor properties.

  7. Pyrimidine and nucleoside gamma-esters of L-Glu-Sar

    DEFF Research Database (Denmark)

    Eriksson, André H; Elm, Peter L; Begtrup, Mikael

    2005-01-01

    quantitatively by specific base-catalysed hydrolysis at pH>6.0. II was labile in aqueous buffer solution, whereas I and III showed appropriate stability for oral administration. In 10% porcine intestinal homogenate, the half-lives of the dipeptide derivatives indicated limited enzyme catalyzed degradation. All......-tetrahydrofuran-3-yl ester)-Sar (I), l-Glu(thymine-1-yl-methyl ester)-Sar (II) and l-Glu(acyclothymidine)-Sar (III) were synthesised and in vitro stability was studied in various aqueous and biological media. Affinity to and translocation via hPEPT1 was investigated in mature Caco-2 cell monolayers, grown...

  8. μ4-Sulfido-bis{(μ-2-furylmethanethiolatobis[tricarbonyliron](Fe—Fe}

    Directory of Open Access Journals (Sweden)

    Cong Han

    2010-07-01

    Full Text Available The title compound, [Fe4(C5H5OS2S(CO12], was prepared by the direct reaction of Fe3(CO12 and 2-furylmethanethiol in tetrahydrofuran. Desulfurization took place readily to form an Fe4S3 cluster. The molecule consists of two similar [(μ-2-C4H3O—CH2SFe2(CO6] moieties joined to a spiro-type four-coordinate μ4-S atom such that this bridging sulfur is tetrahedrally coordinated to the four Fe atoms. In each diiron subcluster core, the 2-furylmethanethiolate ligand bridges the two Fe atoms.

  9. Iminoiodane- and Brønsted Base-Mediated Cross Dehydrogenative Coupling of Cyclic Ethers with 1,3-Dicarbonyl Compounds

    Directory of Open Access Journals (Sweden)

    Ciputra Tejo

    2015-07-01

    Full Text Available A one-pot, two-step approach to prepare 2-tetrahydrofuran and -pyran substituted 1,3-dicarbonyl compounds by PhI=NTs-mediated amination/Brønsted base-catalyzed cross dehydrogenative coupling (CDC reaction of the cyclic ether and 1,3-dicarbonyl derivative under mild conditions is reported. The reaction is compatible with a variety of cyclic ethers and 1,3-dicarbonyl compounds, affording the corresponding coupled products in moderate to good yields of up to 80% over two steps.

  10. Novel protocol for lutein extraction from microalga Chlorella vulgaris

    DEFF Research Database (Denmark)

    D'Este, Martina; De Francisci, Davide; Angelidaki, Irini

    2017-01-01

    Lutein is a pigment generally extracted from marigold flowers. However, lutein is also found in considerable amounts in microalgae. In this study a novel method was developed to improve the extraction efficiency of lutein from microalga C. vulgaris. Differently from conventional methods, ethanol...... purity was increased from 73.6% to 93.7% by decreasing the ethanol-water ratio from 85% to 50% in the resolubilization step. The novel method was also tested with tetrahydrofuran. The extraction proved to be again more effective than the conventional one; however dichloromethane outperformed...

  11. A general approach for the synthesis of bimetallic M–Sn (M = Ru, Rh and Ir) catalysts for efficient hydrogenolysis of ester

    KAUST Repository

    Samal, Akshaya Kumar

    2016-11-24

    A versatile synthetic method was applied for the preparation of Sn containing bimetallic catalysts. The synthesis was performed by simply mixing the super hydride [LiB(C2H5)(3)H], with a metal (Ru, Rh or Ir) salt and an organotin complex in tetrahydrofuran solvent without using any surfactant. This leads to the formation of monodispersed M-Sn (M = Ru, Rh or Ir) bimetallic nanoparticles (NPs). These bimetallic catalysts show high performances in the hydrogenolysis of ester to the corresponding alcohol.

  12. Non-intuitive clustering of 9,10-phenanthrenequinone on Au(111

    Directory of Open Access Journals (Sweden)

    Ryan D. Brown

    2017-08-01

    Full Text Available The direct injection of a 9,10-phenanthrenequinone in tetrahydrofuran solution on a Au(111 substrate in high vacuum results in the formation of metastable clusters with a non-intuitive structure. Metastable, rectangular tetramers of this molecule form in which the net molecular dipoles all orient toward the center of the cluster. This structure does not allow for additional hydrogen bonding and thus the origin of its metastability is not clear. We compare this feature to other structures observed on this surface, as well as those formed during the deposition of 9-fluorenone, which does not exhibit this anomalous clustering behavior.

  13. Automated synthesis of {sup 11}C-acetoacetic acid, a key alternate brain fuel to glucose

    Energy Technology Data Exchange (ETDEWEB)

    Tremblay, Sebastien [Research Center on Aging, Sherbrooke University Geriatric Institute, 1036 Belvedere Street South, Sherbrooke, Quebec, J1H 4C4 (Canada)]. E-mail: Sebastien.Tremblay@USherbrooke.ca; Ouellet, Rene [Sherbrooke Molecular Imaging Centre, Etienne-LeBel Clinical Research Centre, Centre Hospitalier Universitaire de Sherbrooke, Quebec, J1H 5N4 (Canada); Rodrigue, Serge [Sherbrooke Molecular Imaging Centre, Etienne-LeBel Clinical Research Centre, Centre Hospitalier Universitaire de Sherbrooke, Quebec, J1H 5N4 (Canada); Langlois, Rejean [Sherbrooke Molecular Imaging Centre, Etienne-LeBel Clinical Research Centre, Centre Hospitalier Universitaire de Sherbrooke, Quebec, J1H 5N4 (Canada); Department of Nuclear Medicine and Radiobiology, Quebec, J1H 5N4 (Canada); Benard, Francois [Sherbrooke Molecular Imaging Centre, Etienne-LeBel Clinical Research Centre, Centre Hospitalier Universitaire de Sherbrooke, Quebec, J1H 5N4 (Canada); Department of Nuclear Medicine and Radiobiology, Quebec, J1H 5N4 (Canada); Cunnane, Stephen C. [Research Center on Aging, Sherbrooke University Geriatric Institute, 1036 Belvedere Street South, Sherbrooke, Quebec, J1H 4C4 (Canada); Department of Medicine, Faculty of Medicine and Health Sciences, Universite de Sherbrooke, Sherbrooke, Quebec, J1H 5N4 (Canada)

    2007-08-15

    An automated, one-pot radio-synthesis module for the routine preparation of 1-[{sup 11}C]acetoacetic acid has been developed. The enolate anion of acetone was reacted with [{sup 11}C]CO{sub 2} in tetrahydrofuran (THF), followed by hydrolysis and purification by ion-exchange chromatography. The total synthesis time was 18 min and radiochemical yield was 34% after decay correction. HPLC analysis showed {<=}3% impurities while residual THF ({<=}200 ppm) and ethanol ({<=}500 ppm) were well under the tolerable limits for human studies.

  14. 1,3-Dimesitylimidazolidinium tetrachloridogold(III dichloromethane solvate

    Directory of Open Access Journals (Sweden)

    Tesfamariam K. Hagos

    2008-11-01

    Full Text Available The title ionic compound, (C21H27N2[AuCl4]·CH2Cl2, was obtained from the reaction of 1,3-dimesitylimidazolidinium chloride with t-BuOK and a solution of AuCl3 in tetrahydrofuran. In the crystal structure, numerous weak C—H...Cl hydrogen bonds form double layers parallel to (100, which are further stabilized by π–π interactions between mesitylene rings [centroid–centroid distance = 4.308 (4 Å], resulting in the formation of a three-dimensional supramolecular assembly.

  15. Chemical cleaning agents and bonding to glass-fiber posts.

    Science.gov (United States)

    Gonçalves, Ana Paula Rodrigues; Ogliari, Aline de Oliveira; Jardim, Patrícia dos Santos; Moraes, Rafael Ratto de

    2013-01-01

    The influence of chemical cleaning agents on the bond strength between resin cement and glass-fiber posts was investigated. The treatments included 10% hydrofluoric acid, 35% phosphoric acid, 50% hydrogen peroxide, acetone, dichloromethane, ethanol, isopropanol, and tetrahydrofuran. Flat glass-fiber epoxy substrates were exposed to the cleaners for 60 s. Resin cement cylinders were formed on the surfaces and tested in shear. All treatments provided increased bond strength compared to untreated control specimens. All failures were interfacial. Although all agents improved the bond strength, dichloromethane and isopropanol were particularly effective.

  16. Chemical cleaning agents and bonding to glass-fiber posts

    Directory of Open Access Journals (Sweden)

    Ana Paula Rodrigues Gonçalves

    2013-02-01

    Full Text Available The influence of chemical cleaning agents on the bond strength between resin cement and glass-fiber posts was investigated. The treatments included 10% hydrofluoric acid, 35% phosphoric acid, 50% hydrogen peroxide, acetone, dichloromethane, ethanol, isopropanol, and tetrahydrofuran. Flat glass-fiber epoxy substrates were exposed to the cleaners for 60 s. Resin cement cylinders were formed on the surfaces and tested in shear. All treatments provided increased bond strength compared to untreated control specimens. All failures were interfacial. Although all agents improved the bond strength, dichloromethane and isopropanol were particularly effective.

  17. Kinetics of solvent-swelling of coal

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, G.; Rincon, J.M.; Mora, E. [Lab. de Combustibles, Univ. Nacional de Colombia, Santafe de Bogota (Colombia); Klose, W. [GF Thermodynamik, Kassel Univ. (Germany)

    1997-12-31

    The kinetics of coal swelling by solvent of different basic strength is followed; Cerrejon and Yerbabuena (Colombian coals), Sacer-Endsdorf and Ruhr-Anna (Germany coals) were swollen with tetrahydrofuran, pyridine and butylamine. It was found that the swelling index decreases both with solvent basicity and coal rank. When the coal rank increases, the rates of swelling are: Initially, THF follows Fickian diffusion then follows anomalous case near case II; pyridine follows anomalous case near Fickian diffusion, whereas rate with butylamine initially is anomalous case of transport to Fickian diffusion. (orig.)

  18. Stable high-order molecular sandwiches: Hydrocarbon polyanion pairs with multiple lithium ions inside and out

    Energy Technology Data Exchange (ETDEWEB)

    Ayalon, A.; Rabinovitz, M. (Hebrew Univ. of Jerusalem (Israel)); Sygula, A.; Rabideau, P.W. (Louisiana State Univ., Baton Rouge, LA (United States)); Cheng, P.C.; Scott, L.T. (Boston College, Chestnut Hill, MA (United States))

    1994-08-19

    Stable ten-component sandwich compounds have been characterized in which four lithium ions reside between two tetraanions derived from corannulene or its alkyl-substituted derivatives and four additional lithium ions decorate the exterior. In tetrahydrofuran solution, the four lithium ions inside the sandwich can exchange environments with the four external lithium atoms, but the two tetraanion decks of the sandwich never separate from one another on the time scale of nuclear magnetic resonance. Theoretical calculations point to a [open quotes]stacked bowl[close quotes] conformation and a low energy barrier for synchronous double inversion of the tetraanion bowls in the solvated sandwich compounds.

  19. Synthesis, characterisation and antimicrobial activity of (5-bromo-5-nitro-2-oxido-1,3,2-dioxaphosphinan-2-yl amino acid esters

    Directory of Open Access Journals (Sweden)

    CIRANDUR SURESH REDDY

    2011-05-01

    Full Text Available Synthesis of a new series of (5-bromo-5-nitro-2-oxido-1,3,2-dioxaphosphinan-2-ylamino acid esters (3a–l was accomplished via a two step process, which involves the prior preparation of the monochloride intermediate (2 and its subsequent reaction with the amino acid esters in dry tetrahydrofuran in the presence of triethylamine at reflux temperature. The title compounds (3a–l structures were established by analytical, IR, 1H-, 13C- and 31P-NMR, and mass spectral data. They exhibited significant antibacterial and antifungal activity.

  20. One-step catalytic conversion of biomass-derived carbohydrates to liquid fuels

    Science.gov (United States)

    Sen, Ayusman; Yang, Weiran

    2014-03-18

    The invention relates to a method for manufacture of hydrocarbon fuels and oxygenated hydrocarbon fuels such as alkyl substituted tetrahydrofurans such as 2,5-dimethyltetrahydrofuran, 2-methyltetrahydrofuran, 5-methylfurfural and mixtures thereof. The method generally entails forming a mixture of reactants that includes carbonaceous material, water, a metal catalyst and an acid reacting that mixture in the presence of hydrogen. The reaction is performed at a temperature and for a time sufficient to produce a furan type hydrocarbon fuel. The process may be adapted to provide continuous manufacture of hydrocarbon fuels such as a furan type fuel.

  1. The Mark-Houwink-Sakurada Relation for Poly(Methyl Methacrylate)

    Science.gov (United States)

    Wagner, Herman L.

    1987-04-01

    In this third review of a series, the literature values for the viscosity-molecular weight relationship (Mark-Houwink-Sakurada) for poly(methyl methacrylate) have been critically evaluated. Although most of the studies have been concerned with conventionally produced poly(methyl methacrylate), some work has also been done with the isotactic polymer. The Mark-Houwink relations for the following solvents are discussed: benzene, toluene, acetone, chloroform, 2-butanone, and tetrahydrofuran, as well as for several other infrequently used solvents. The values of the coefficient K in the relation [η]=KM0.5 for several theta solvents are also reported.

  2. Antioxidant lignoids from leaves of Ribes nigrum.

    Science.gov (United States)

    Sasaki, Tatsunori; Li, Wei; Zaike, Shinnosuke; Asada, Yoshihisa; Li, Qin; Ma, Fenghua; Zhang, Qingbo; Koike, Kazuo

    2013-11-01

    Phytochemical investigation of the leaves of Ribes nigrum resulted in the isolation of fourteen compounds, including four 7,7'-epoxylignans, three tetrahydrofuran-type sesquilignans, and a spirocyclic dilignan. Their structures were elucidated by extensive spectroscopic analyses and by chemical transformations. The isolated compounds were evaluated for their antioxidant activities using superoxide anion scavenging assay and DPPH free radical scavenging assay. Ribesin D and ribesin G showed the most potent superoxide anion scavenging activity with EC50 values of 1.24 and 1.12 μM, respectively, and the structure-activity relationship was discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Biocatalytic Synthesis of Novel Partial Esters of a Bioactive Dihydroxy 4-Methylcoumarin by Rhizopus oryzae Lipase (ROL).

    Science.gov (United States)

    Kumar, Vinod; Mathur, Divya; Srivastava, Smriti; Malhotra, Shashwat; Rana, Neha; Singh, Suraj K; Singh, Brajendra K; Prasad, Ashok K; Varma, Anjani J; Len, Christophe; Kuhad, Ramesh C; Saxena, Rajendra K; Parmar, Virinder S

    2016-11-09

    Highly regioselective acylation has been observed in 7,8-dihydroxy-4-methylcoumarin (DHMC) by the lipase from Rhizopus oryzae suspended in tetrahydrofuran (THF) at 45 °C using six different acid anhydrides as acylating agents. The acylation occurred regioselectively at one of the two hydroxy groups of the coumarin moiety resulting in the formation of 8-acyloxy-7-hydroxy-4-methylcoumarins, which are important bioactive molecules for studying biotansformations in animals, and are otherwise very difficult to obtain by only chemical steps. Six monoacylated, monohydroxy 4-methylcoumarins have been biocatalytically synthesised and identified on the basis of their spectral data and X-ray crystal analysis.

  4. 8a-Methyl-5,6,8,8a,9,10-hexahydro-10,12a-epoxyisoindolo[1,2-a]isoquinolinium iodide

    Directory of Open Access Journals (Sweden)

    Flavien A. A. Toze

    2010-06-01

    Full Text Available The title compound, C17H18NO+·I−, is an adduct resulting from an intramolecular Diels–Alder reaction of methallyl chloride with 3,4-dihydro-1-furylisoquinoline. The cation comprises a fused pentacyclic system containing three five-membered rings (dihydropyrrole, dihydrofuran and tetrahydrofuran and two six-membered rings (tetrahydropyridine and benzene. The five-membered rings have the usual envelope conformations, and the central six-membered tetrahydropyridine ring adopts the unsymmetrical half-boat conformation. In the crystal, cations and iodide anions are bound by weak intermolecular hydrogen-bonding interactions into a three-dimensional framework.

  5. Electrospinning of Polyvinylidene Fluoride and Polyetherimide From Mixed Solvents

    Science.gov (United States)

    Morgret, Leslie D.; Pawlowski, Kristin J.; Hinkley, Jeffrey A.

    2005-01-01

    Polyvinylidene fluoride and Ultem(TradeMark) polyetherimide were dissolved in 50/50 acetone/N,N dimethylformamide (DMF) and 80/20 tetrahydrofuran/DMF, respectively, and electrospun. Polymer solution concentrations and molecular weights were changed while other spinning parameters (voltage, distance, solution feed rate) were held constant. Fiber diameters in the resulting electrospun mats varied from 0.25 to 4.4 microns, increasing with polymer concentration and molecular weight; trends in diameter were compared with trends in viscosities and surface tensions of the spinning solutions.

  6. 2-Methyl-1,3-benzoxazol-4-yl diphenylphosphinate

    Directory of Open Access Journals (Sweden)

    Dewald J. Kleinhans

    2011-02-01

    Full Text Available The title compound, C20H16NO3P, was synthesized by the addition of diphenylphosphine chloride to a tetrahydrofuran solution of Et3N and 2-methyl-1,3-benzoxazol-4-ol at 233 K. In the molecule, the almost planar (r.m.s. deviation = 0.010 Å benzoxazole moiety is attached to the slightly distorted tetrahedral P atom [C—P—C—C torsion angle = 132.20 (18°]. The crystal structure does not exhibit any significant intermolecular interactions.

  7. Amino sugars in suspended particulate matter from the Bay of Bengal during the summer monsoon of 2001

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, L.; DeSouza, F.P.; Matondkar, S.G.P.; Bhosle, N.B.

    and Sri Lanka on the west and by the Andaman?Nicobar islands and Burma on the east. The uniqueness of the Bay is the reversing monsoons that cause seasonal changes in circulation and weather. Furthermore, the Bay receives large quantities of fresh water...) and reversed phase Shim-Pack HRC-ODS analytical column (4.6 mm ID, 15 cm length, 5?m particle size) was used. A binary solvent system consisting of 50mM sodium acetate buffer (pH 6.5) containing 3% of tetrahydrofuran as solvent A and methanol as solvent B...

  8. Rhodium-Catalyzed Intramolecular C-H Bond Activation with Triazoles: Preparation of Stereodefined Pyrrolidines and Other Related Cyclic Compounds.

    Science.gov (United States)

    Senoo, Masato; Furukawa, Ayana; Hata, Takeshi; Urabe, Hirokazu

    2016-01-18

    On treatment of triazoles having an N-sulfonyl-protected benzylamine moiety with [Rh2 (C7 H15 CO2 )4 ], intramolecular C-H bond insertion takes place at the benzylic position to give cis-N-sulfonyl-2-aryl-3-[(sulfonylimino)methyl]pyrrolidines in good yields and with highly stereoselectivities. Analogously, the similar treatment of triazoles having an ether or even an alkyl moiety affords 2-alkyl- or 2-aryl-3-[(sulfonylimino)methyl]tetrahydrofurans or a 2-alkyl-3-[(sulfonylimino)methyl]cyclopentane in good yields. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. The oxidation of chiral alcohols catalyzed by catalase in organic solvents

    Energy Technology Data Exchange (ETDEWEB)

    Magner, E.; Klibanov, A.M. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemistry

    1995-04-20

    The catalytic properties of bovine liver catalase have been investigated in organic solvents. In tetrahydrofuran, dioxane, and acetone (all containing 1% to 3% of water), the enzyme breaks down tert-butyl hydroperoxide several fold faster than in pure water. Furthermore, the rate of catalase-catalyzed production of tert-butanol from tert-butyl hydroperoxide increases more than 400-fold upon transition from aqueous buffer to ethanol as the reaction medium. The mechanistic rationale for this striking effect is that in aqueous buffer the rate-limiting step of the enzymatic process involves the reduction of catalase`s compound 1 by tert-butyl hydroperoxide. In ethanol, an additional step in the reaction scheme becomes available in which ethanol, greatly outcompeting the hydroperoxide, is oxidized by compound 1 regenerating the free enzyme. In solvents, such as acetonitrile or tetrahydrofuran, which themselves are not oxidizable by compound 1, catalase catalyzes the oxidation of numerous primary and secondary alcohols with tert-butyl hydroperoxide to the corresponding aldehydes or ketones. The enzymatic oxidation of some chiral alcohols (2,3-butanediol, citronellol, and menthol) under these conditions occurs enantioselectively. Examination of the enantioselectivity for the oxidation of 2,3-butanediol in a series of organic solvents reveals a considerable solvent dependence.

  10. Factors screening to statistical experimental design of racemic atenolol kinetic resolution via transesterification reaction in organic solvent using free Pseudomonas fluorescens lipase.

    Science.gov (United States)

    Agustian, Joni; Kamaruddin, Azlina Harun; Aboul-Enein, Hassan Y

    2017-07-01

    As the (R)-enantiomer of racemic atenolol has no β-blocking activity and no lack of side effects, switching from the racemate to the (S)-atenolol is more favorable. Transesterification of racemic atenolol using free enzymes investigated as a resource to resolve the racemate via this method is limited. Screenings of enzyme, medium, and acetyl donor were conducted first to give Pseudomonas fluorescens lipase, tetrahydrofuran, and vinyl acetate. A statistical design of the experiment was then developed using Central Composite Design on some operational factors, which resulted in the conversions of 11.70-61.91% and substrate enantiomeric excess (ee) of 7.31-100%. The quadratic models are acceptable with R 2 of 95.13% (conversion) and 89.63% (ee). The predicted values match the observed values reasonably well. Temperature, agitation speed, and substrate molar ratio factor have low effects on conversion and ee, but enzyme loading affects the responses highly. The interaction of temperature-agitation speed and temperature-substrate molar ratio show significant effects on conversion, while temperature-agitation speed, temperature-substrate molar ratio, and agitation speed-substrate molar ratio affect ee highly. Optimum conditions for the use of Pseudomonas fluorescens lipase, tetrahydrofuran, and vinyl acetate were found at 45°C, 175 rpm, 2000 U, and 1:3.6 substrate molar ratio. © 2017 Wiley Periodicals, Inc.

  11. PVC/carbon nanotubes nanocomposites: evaluation of electrical resistivity and the residual solvent effect over the thermal properties of nanocomposites; Nanocompositos PVC/nanotubos de carbono: avaliacao da resistividade eletrica e efeito do solvente utilizado na obtencao dos nanocompositos nas propriedades termicas

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Rogerio Gomes [Instituto Superior Tupy (UNISOCIESC), Joinville, SC (Brazil); Pires, Alfredo T.N., E-mail: araujo@sociesc.org.br [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

    2013-07-01

    The procedure for obtaining nanocomposite by dispersing the nanoparticles in matrix polymer in solution with subsequent elimination of the solvent has been widely used, considering better efficiency in obtaining homogeneity of the final product. However, the presence of residual solvent may affect the nanocomposites in micro-and macroscopic properties of the product. The aim of this study was to evaluate the thermal properties of nanocomposites of poly(vinylchloride)/multi-walled carbon nanotube obtained from the polymer solution and dispersion of carbon nanotubes in tetrahydrofuran (THF), as well as the electrical resistivity of nanocomposites and the influence of residual solvent. The presence of residual tetrahydrofuran reduces the glass transition temperature (Tg) up to 26 °C, being independent of the amount of carbon nanotubes. The total elimination of the solvent is an important factor that does not induce changes in the properties of the polymeric matrix. The graft-COOH groups in the structure of the nanotubes leads to a considerable reduction of the electrical resistivity in ten orders of magnitude, from 0.4 %wt of nanotubes in the nanocomposite composition. (author)

  12. Synthesis and properties of methacrylic-functionalized tween monomer networks.

    Science.gov (United States)

    Muzzalupo, Rita; Tavano, Lorena; Rossi, Cesare Oliviero; Cassano, Roberta; Trombino, Sonia; Picci, Nevio

    2009-02-03

    Tween surfactants possess very interesting properties such as biodegradability, biocompatibility, and low toxicity. The synthesis of acrylate monomers by means of the chemical modification of polysorbate surfactants Tween 20, 40, and 60 with unsaturated groups is described. Monomers were obtained as a result of the reaction of methacrylic anhydride with different grades of Tween surfactants. Further polymerization was carried out in tetrahydrofuran, dimethylformamide, and a mixture of water-tetrahydrofuran. Physicochemistry properties of the polymer networks were investigated, and the obtained results reveal that they strongly depend on the type of solvent used during the polymerization, as well as on the concentration of the casting solution. In particular, our study demonstrated that, depending on the solvent boiling point, i.e., the facility to remove the solvent from the polymer matrix, it is possible to predict properties of the network morphology. Moreover, in vitro studies on controlled release were accomplished to demonstrate the possibility of utilizing these new materials as drug delivery systems. All resulting networks represent a novel class of cross-linked polymeric materials useful both in pharmaceutical and chemical applications.

  13. Nanocellulose Derivative/Silica Hybrid Core-Shell Chiral Stationary Phase: Preparation and Enantioseparation Performance

    Directory of Open Access Journals (Sweden)

    Xiaoli Zhang

    2016-05-01

    Full Text Available Core-shell silica microspheres with a nanocellulose derivative in the hybrid shell were successfully prepared as a chiral stationary phase by a layer-by-layer self-assembly method. The hybrid shell assembled on the silica core was formed using a surfactant as template by the copolymerization reaction of tetraethyl orthosilicate and the nanocellulose derivative bearing triethoxysilyl and 3,5-dimethylphenyl groups. The resulting nanocellulose hybrid core-shell chiral packing materials (CPMs were characterized and packed into columns, and their enantioseparation performance was evaluated by high performance liquid chromatography. The results showed that CPMs exhibited uniform surface morphology and core-shell structures. Various types of chiral compounds were efficiently separated under normal and reversed phase mode. Moreover, chloroform and tetrahydrofuran as mobile phase additives could obviously improve the resolution during the chiral separation processes. CPMs still have good chiral separation property when eluted with solvent systems with a high content of tetrahydrofuran and chloroform, which proved the high solvent resistance of this new material.

  14. Critical analysis of the accuracy of models predicting or extracting liquid structure information.

    Science.gov (United States)

    Van Houteghem, Marc; Ghysels, An; Verstraelen, Toon; Poelmans, Ward; Waroquier, Michel; Van Speybroeck, Veronique

    2014-03-06

    This work aims at a critical assessment of properties predicting or extracting information on the density and structure of liquids. State-of-the-art NVT and NpT molecular dynamics (MD) simulations have been performed on five liquids: methanol, chloroform, acetonitrile, tetrahydrofuran, and ethanol. These simulations allow the computation of properties based on first principles, including the equilibrium density and radial distribution functions (RDFs), characterizing the liquid structure. Refinements have been incorporated in the MD simulations by taking into account basis set superposition errors (BSSE). An extended BSSE model for an instantaneous evaluation of the BSSE corrections has been proposed, and their impact on the liquid properties has been assessed. If available, the theoretical RDFs have been compared with the experimentally derived RDFs. For some liquids, significant discrepancies have been observed, and a profound but critical investigation is presented to unravel the origin of these deficiencies. This discussion is focused on tetrahydrofuran where the experiment reveals some prominent peaks completely missing in any MD simulation. Experiments providing information on liquid structure consist mainly of neutron diffraction measurements offering total structure factors as the primary observables. The splitting of these factors in reciprocal space into intra- and intermolecular contributions is extensively discussed, together with their sensitivity in reproducing correct RDFs in coordinate space.

  15. Association and Dissociation of Grignard Reagents RMgCl and Their Turbo Variant RMgCl⋅LiCl.

    Science.gov (United States)

    Schnegelsberg, Christoph; Bachmann, Sebastian; Kolter, Marlene; Auth, Thomas; John, Michael; Stalke, Dietmar; Koszinowski, Konrad

    2016-06-01

    Grignard reagents RMgCl and their so-called turbo variant, the highly reactive RMgCl⋅LiCl, are of exceptional synthetic utility. Nevertheless, it is still not fully understood which species these compounds form in solution and, in particular, in which way LiCl exerts its reactivity-enhancing effect. A combination of electrospray-ionization mass spectrometry, electrical conductivity measurements, NMR spectroscopy (including diffusion-ordered spectroscopy), and quantum chemical calculations is used to analyze solutions of RMgCl (R=Me, Et, Bu, Hex, Oct, Dec, iPr, tBu, Ph) in tetrahydrofuran and other ethereal solvents in the absence and presence of stoichiometric amounts of LiCl. In tetrahydrofuran, RMgCl forms mononuclear species, which are converted into trinuclear anions as a result of the concentration increase experienced during the electrospray process. These trinuclear anions are theoretically predicted to adopt open cubic geometries, which remarkably resemble structural motifs previously found in the solid state. The molecular constituents of RMgCl and RMgCl⋅LiCl are interrelated via Schlenk equilibria and fast intermolecular exchange processes. A small portion of the Grignard reagent also forms anionic ate complexes in solution. The abundance of these more electron-rich and hence supposedly more nucleophilic ate complexes strongly increases upon the addition of LiCl, thus rationalizing its beneficial effect on the reactivity of Grignard reagents. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. POROGEN EFFECT TOWARDS THE QUALITY OF CURCUMIN IMPRINTED POLYMER

    Directory of Open Access Journals (Sweden)

    Emi Shaqiza Azizi

    2011-12-01

    Full Text Available Molecularly imprinted polymer (MIP is gaining importance in separation technology. In this study, curcumin has been selected as template in MIP which can be applied as sorbent materials in solid-phase extraction (SPE. Effect of porogen on the quality of curcumin-MIP is very sensitive depends on the molecular size and polarity of the porogen. We varied three solvents as the porogen i.e. tetrahydrofuran (THF, chloroform (CHCl3 and acetonitrile (MeCN. The MIP was prepared using non-covalent approach through bulk polymerization and non-imprinted polymer (NIP as control, also prepared using the same procedure in the absence of template. The largest imprinting factor, 1.27 was obtained from polymer P1 at ratio 1:4 of template: functional monomer. The P1 was prepared using methacrylic acid (MAA as functional monomer and tetrahydrofuran (THF as porogen with the highest average pore diameter i.e. 618.43 nm trough gas adsorption analysis. This will lead to better access of curcumin during batch binding analysis.

  17. Crystal structure of methyl (3RS,4SR,4aRS,11aRS,11bSR-5-oxo-3,4,4a,5,7,8,9,10,11,11a-decahydro-3,11b-epoxyazepino[2,1-a]isoindole-4-carboxylate

    Directory of Open Access Journals (Sweden)

    Flavien A. A. Toze

    2015-10-01

    Full Text Available The title compound, C15H19NO4, is the a product of the esterification of the corresponding carbonic acid with methanol. The molecule comprises a fused tetracyclic system containing three five-membered rings (2-pyrrolidinone, tetrahydrofuran and dihydrofuran and one seven-membered ring (azepane. The five-membered rings have the usual envelope conformations, with the quaternary C atom being the flap atom for the 2-pyrrolidinone ring, and the ether O atom being the common flap atom for the remaining rings. The seven-membered azepane ring adopts a chair conformation with the methine and middle methylene C atoms lying above and below the mean plane defined by the remaining five atoms. The carboxylate substituent is rotated by 77.56 (5° with respect to the base plane of the tetrahydrofuran ring. In the crystal, the molecules are bound by weak C—H...O hydrogen-bonding interactions into puckered layers parallel to (001.

  18. Intestinal distribution and excretion of sesaminol and its tetrahydrofuranoid metabolites in rats.

    Science.gov (United States)

    Jan, Kuo-Ching; Ku, Kuo-Lung; Chu, Yan-Hwa; Hwang, Lucy Sun; Ho, Chi-Tang

    2011-04-13

    Sesame seeds (Sesamum indicum L.) are unique because of potent and various physiological activities imparted by their bioactive lignans. This investigation studied the intestinal distribution and excretion of sesaminol in Sprague-Dawley (SD) rats. To investigate the distribution of sesaminol (per oral 220 mg/kg), the changes in concentration of sesaminol and its metabolites were determined in the intestines and plasma within the 24 h period after tube feeding of sesaminol to SD rats. Results show that the epimerization of sesaminol appeared to be catalyzed by acid in the simulated gastric fluids. The major sesaminol epimer was characterized as 2-episesaminol using 2D-NMR. These findings indicate that sesame sesaminol and its epimer are poorly absorbed prior to reaching the rectum and that substantial amounts pass from the small to the large intestine, where they are metabolized by the colonic microflora to tetrahydrofuranoid metabolites. Sesaminol in plasma was largely present as phase II conjugates, and the seven metabolites were detected as the 2-episesaminol, sesaminol-6-catechol, methylated sesaminol-catechol, R,R-hydroxymethylsesaminol-tetrahydrofuran, S,R-hydroxymethylsesaminol-tetrahydrofuran, enterolactone, and enterodiol. Excretions of sesaminol in urine and feces within the 24 h period were equivalent to 0.02 and 9.33% of the amount ingested, respectively.

  19. Tissue distribution and cytochrome P450 inhibition of sesaminol and its tetrahydrofuranoid metabolites.

    Science.gov (United States)

    Jan, Kuo-Ching; Chang, Yi-Wei; Hwang, Lucy Sun; Ho, Chi-Tang

    2012-09-05

    Sesame lignans such as sesamin, sesaminol, and sesamolin are major constituents of sesame oil, and all have a methylenedioxyphenyl group and multiple functions in vivo. It was previously reported that sesaminol, a tetrahydrofurofuran type lignin, was metabolized to mammalian lignans. The present study examined the tissue distribution of sesaminol in Sprague-Dawley (SD) rats. Changes in the concentration of sesaminol and its metabolites (sesaminol glucuronide/sulfate, hydroxymethylsesaminol-tetrahydrofuran, enterolactone, and enterodiol) were determined in tissues within a 24 h period after tube feeding (po 220 mg/kg) to SD rats. The concentrations of enterodiol and enterolactone were significantly higher than those of sesaminol and its tetrahydrofuranoid metabolites in the organs (liver, heart, brain, and kidney). This study demonstrates that sesaminol has potent inhibition of cytochrome P450 (CYPs), compared to tetrahydrofuranoid metabolites. The IC(50) values of CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 for sesaminol were determined as 3.57, 3.93, 0.69, 1.33, and 0.86 μM, respectively. In addition, hydroxymethylsesaminol-tetrahydrofuran and enterodiol were weak inhibitors of CYP2C9 and CYP1A2, respectively.

  20. Analyses of Acidic Tar Dyes in High-Protein Foods and Examination of Extraction and Clean-Up Methods for Various Foods.

    Science.gov (United States)

    Osuga, Asa; Uematsu, Yoko; Yamajima, Yukiko; Fujiwara, Takushi; Tahara, Shoichi; Miyakawa, Hiroyuki; Monma, Kimio

    2017-01-01

    Extraction and clean-up methods were examined for the analysis of acidic tar dyes in various high-protein foods. 1% Aqueous ammonia followed by ethanol, 1% aqueous ammonia-ethanol (1 : 1) mixture, and 1% aqueous ammonia-tetrahydrofuran (1 : 1) mixture were used in sequence for boiled fish paste (kamaboko), pounded fish cake (hanpen), and sausage. The sausage extract was centrifuged at low temperature to solidify and remove the contained fat. Salted cod roe with red pepper was extracted twice with 1% aqueous ammonia-ethanol (1 : 1) mixture, followed by extraction with 1% aqueous ammonia-tetrahydrofuran (1 : 1) mixture. A divinylbenzene-N-vinylpyrrolidone copolymer column was used for the clean-up of xanthen dyes. In the case of clogging-prone samples, the same type of large-particle-size column was used. A polyamide column was used for clean-up of the other dyes. When each dye was added at 5 μg/g in the foods, recoveries from kamaboko, hanpen, and sausage ranged from 76 to 102%, and the average recovery from the two types of salted cold roe with red pepper ranged from 45 to 98%.

  1. Hydroformylation of dihydrofurans catalyzed by rhodium complex encapsulated hexagonal mesoporous silica

    KAUST Repository

    Khokhar, Munir

    2015-05-01

    HRh(CO)(PPh3)3 encapsulated hexagonal mesoporous silica (HMS) is found to be an efficient heterogeneous catalyst for the selective hydroformylation of 2,3-dihydrofuran (2,3DHF) and 2,5-dihydrofuran (2,5DHF). The Rh-complex encapsulated in situ in the organic phase of template inside the pores of HMS was found to act as nano phase reactors. Conversion of 2,3-DHF and 2,5-DHF and selectivity of the corresponding aldehydes were thoroughly investigated by studying the reaction parameters: catalyst amount, substrate concentration, partial as well as total pressure of CO and H2, and temperature. The selectivity for the formation of tetrahydrofuran-2-carbaldehyde (THF-2-carbaldehyde) from the hydroformylation of 2,3-DHF was found to be more than the selectivity of the formation of tetrahydrofuran-3-carbaldehyde (THF-3-carbaldehyde) from 2,5-DHF. The reaction paths are suggested and discussed for the selective formation of the corresponding aldehydes. The catalyst was elegantly separated and effectively recycled for six times.

  2. Size characterization of metal oxide nanoparticles in commercial sunscreen products

    Science.gov (United States)

    Bairi, Venu Gopal; Lim, Jin-Hee; Fong, Andrew; Linder, Sean W.

    2017-07-01

    There is an increase in the usage of engineered metal oxide (TiO2 and ZnO) nanoparticles in commercial sunscreens due to their pleasing esthetics and greater sun protection efficiency. A number of studies have been done concerning the safety of nanoparticles in sunscreen products. In order to do the safety assessment, it is pertinent to develop novel analytical techniques to analyze these nanoparticles in commercial sunscreens. This study is focused on developing analytical techniques that can efficiently determine particle size of metal oxides present in the commercial sunscreens. To isolate the mineral UV filters from the organic matrices, specific procedures such as solvent extraction were identified. In addition, several solvents (hexane, chloroform, dichloromethane, and tetrahydrofuran) have been investigated. The solvent extraction using tetrahydrofuran worked well for all the samples investigated. The isolated nanoparticles were characterized by using several different techniques such as transmission electron microscopy, scanning electron microscopy, dynamic light scattering, differential centrifugal sedimentation, and x-ray diffraction. Elemental analysis mapping studies were performed to obtain individual chemical and morphological identities of the nanoparticles. Results from the electron microscopy techniques were compared against the bulk particle sizing techniques. All of the sunscreen products tested in this study were found to contain nanosized (≤100 nm) metal oxide particles with varied shapes and aspect ratios, and four among the 11 products were showed to have anatase TiO2.

  3. Secondary Metabolites in Allergic Plant Pollen Samples Modulate Afferent Neurons and Murine Tracheal Rings.

    Science.gov (United States)

    Božičević, Alen; De Mieri, Maria; Nassenstein, Christina; Wiegand, Silke; Hamburger, Matthias

    2017-11-22

    Plant pollens are strong airborne elicitors of asthma. Their proteinaceous allergens have been studied intensively, but little is known about a possible contribution of pollen secondary metabolites to the nonallergic exacerbation of asthma. Pollen samples originating from 30 plant species were analyzed by HPLC coupled to PDA, ESIMS, and ELSD detectors and off-line NMR spectroscopy. Polyamine conjugates, flavonoids, and sesquiterpene lactones were identified. Polyamine conjugates were characteristic of all Asteraceae species. The presence of sesquiterpene lactones in Asteraceae pollen varied between species and pollen lots. All plant pollen, including those from non-Asteraceae species, contained to some extent electrophiles as determined by their reaction with N-acetyl-l-cysteine. Selected pollen extracts and pure compounds were tested in murine afferent neurons and in murine tracheal preparations. Tetrahydrofuran extracts of Ambrosia artemisiifolia and Ambrosia psilostachya pollen and a mixture of sesquiterpene lactones coronopilin/parthenin increased the intracellular Ca2+ concentration in 15%, 32%, and 37% of cinnamaldehyde-responsive neurons, respectively. In organ bath experiments, only the sesquiterpene lactones tested induced a weak dilatation of naïve tracheas and strongly lowered the maximal methacholine-induced tracheal constriction. A tetrahydrofuran extract of A. psilostachya and coronopilin/parthenin led to a time-dependent relaxation of the methacholine-preconstricted trachea. These results provide the first evidence for a potential role of pollen secondary metabolites in the modulation of the tracheal tone.

  4. Accelerated solvent extraction of carotenoids from: Tunisian Kaki (Diospyros kaki L.), peach (Prunus persica L.) and apricot (Prunus armeniaca L.).

    Science.gov (United States)

    Zaghdoudi, Khalil; Pontvianne, Steve; Framboisier, Xavier; Achard, Mathilde; Kudaibergenova, Rabiga; Ayadi-Trabelsi, Malika; Kalthoum-Cherif, Jamila; Vanderesse, Régis; Frochot, Céline; Guiavarc'h, Yann

    2015-10-01

    Extraction of carotenoids from biological matrices and quantifications remains a difficult task. Accelerated solvent extraction was used as an efficient extraction process for carotenoids extraction from three fruits cultivated in Tunisia: kaki (Diospyros kaki L.), peach (Prunus persica L.) and apricot (Prunus armeniaca L.). Based on a design of experiment (DoE) approach, and using a binary solvent consisting of methanol and tetrahydrofuran, we could identify the best extraction conditions as being 40°C, 20:80 (v:v) methanol/tetrahydrofuran and 5 min of extraction time. Surprisingly and likely due to the high extraction pressure used (103 bars), these conditions appeared to be the best ones both for extracting xanthophylls such as lutein, zeaxanthin or β-cryptoxanthin and carotenes such as β-carotene, which present quite different polarities. Twelve surface responses were generated for lutein, zeaxanthin, β-cryptoxanthin and β-carotene in kaki, peach and apricot. Further LC-MS analysis allowed comparisons in carotenoids profiles between the fruits. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Electric Field Simulation and Effect of Different Solvent Ratios on the Performance of Single Electrospun PVDF/PEI Composite Film

    Directory of Open Access Journals (Sweden)

    Jin-gang Jiang

    2016-01-01

    Full Text Available On the basis of the finite element calculation theory of electric field, the electric field distribution in a representative electrospinning device is computed. The electric field structure of a needle-plate type electrospinning device was simulated by means of ANSYS software. And the vector distribution of the nozzle on the spinneret pipe was got. For the purpose of the analysis on the influence of different solvent ratios on the performance of a single electrospun PVDF/PEI composite film, polyvinylidene fluoride and polyetherimide with a mass ratio of 8/2 were dissolved in a mixed solvent. The mixed solvent is composed of N,N-dimethylformamide and tetrahydrofuran, added in different proportions. Through the electrostatic spinning technology, PVDF/PEI composite fiber membranes were prepared. Using scanning electron microscopy (SEM, X-ray diffraction (XRD, differential scanning calorimetry (DSC, and mechanical properties testing, the effects of tetrahydrofuran on the composite microstructure, crystallinity, and mechanical properties of the PVDF/PEI composite fiber membranes are discussed.

  6. Crystal structures of hibiscus acid and hibiscus acid dimethyl ester isolated from Hibiscus sabdariffa (Malvaceae).

    Science.gov (United States)

    Zheoat, Ahmed M; Gray, Alexander I; Igoli, John O; Kennedy, Alan R; Ferro, Valerie A

    2017-09-01

    The biologically active title compounds have been isolated from Hibiscus sabdariffa plants, hibiscus acid as a dimethyl sulfoxide monosolvate [systematic name: (2S,3R)-3-hy-droxy-5-oxo-2,3,4,5-tetra-hydro-furan-2,3-di-carb-oxy-lic acid dimethyl sulfoxide monosolvate], C6H6O7·C2H6OS, (I), and hibiscus acid dimethyl ester [systematic name: dimethyl (2S,3R)-3-hy-droxy-5-oxo-2,3,4,5-tetra-hydro-furan-2,3-di-carboxyl-ate], C8H10O7, (II). Compound (I) forms a layered structure with alternating layers of lactone and solvent mol-ecules, that include a two-dimensional hydrogen-bonding construct. Compound (II) has two crystallographically independent and conformationally similar mol-ecules per asymmetric unit and forms a one-dimensional hydrogen-bonding construct. The known absolute configuration for both compounds has been confirmed.

  7. Cellulose multilayer Membranes manufacture with Ionic liquid

    KAUST Repository

    Livazovic, Sara

    2015-05-09

    Membrane processes are considered energy-efficient for water desalination and treatment. However most membranes are based on polymers prepared from fossil petrochemical sources. The development of multilayer membranes for nanofiltration and ultrafiltration, with thin selective layers of naturally available cellulose has been hampered by the availability of non-aggressive solvents. We propose the manufacture of cellulose membranes based on two approaches: (i) silylation, coating from solutions in tetrahydrofuran, followed by solvent evaporation and cellulose regeneration by acid treatment; (ii) casting from solution in 1-ethyl-3-methylimidazolum acetate ([C2mim]OAc), an ionic liquid, followed by phase inversion in water. By these methods porous supports could be easily coated with semi-crystalline cellulose. The membranes were hydrophilic with contact angles as low as 22.0°, molecular weight cut-off as low as 3000 g mol-1 with corresponding water permeance of 13.8 Lm−2 h−1 bar−1. Self-standing cellulose membranes were also manufactured without porous substrate, using only ionic liquid as green solvent. This membrane was insoluble in water, tetrahydrofuran, hexane, N,N-dimethylformamide, 1-methyl-2-pyrrolidinone and N,N-dimethylacetamide.

  8. (3R,3aR,6R,6aR-Hexahydrofuro[3,2-b]furan-3,6-diyl dibenzoate

    Directory of Open Access Journals (Sweden)

    Vincenzo Piccialli

    2013-09-01

    Full Text Available The title compound, C20H18O6, prepared from d-mannitol by a two-step procedure, is a functionalized fused bis-tetrahydrofuran. In the central fragment, consisting of two fused tetrahydrofuran rings, one O atom and its two adjacent C atoms, a methylene and a bridgehead C atom, are disordered over two sets of sites with an occupancy ratio of 0.735 (9:0.265 (9. In the major component, the ring containing the disordered O atom is a half-chair conformation with twisted methylene and benzoate-substituted C atoms, whereas the other ring has a half-chair or T-form conformation. In the minor component, the ring with the disordered O atom has an envelope conformation, with the O atom as the flap, and the other ring has a half-chair conformation, with the O atom and the other bridgehead CH atom being twisted. The two aromatic rings are inclined to one another by 20.00 (12°. In the crystal, adjacent molecules are linked via C—H...π interactions, forming chains propagating along [010].

  9. Biofuel and chemical production by recombinant microorganisms via fermentation of proteinaceous biomass

    Science.gov (United States)

    Liao, James C.; Cho, Kwang Myung; Yan, Yajun; Huo, Yixin

    2016-03-15

    Provided herein are metabolically modified microorganisms characterized by having an increased keto-acid flux when compared with the wild-type organism and comprising at least one polynucleotide encoding an enzyme that when expressed results in the production of a greater quantity of a chemical product when compared with the wild-type organism. The recombinant microorganisms are useful for producing a large number of chemical compositions from various nitrogen containing biomass compositions and other carbon sources. More specifically, provided herein are methods of producing alcohols, acetaldehyde, acetate, isobutyraldehyde, isobutyric acid, n-butyraldehyde, n-butyric acid, 2-methyl-1-butyraldehyde, 2-methyl-1-butyric acid, 3-methyl-1-butyraldehyde, 3-methyl-1-butyric acid, ammonia, ammonium, amino acids, 2,3-butanediol, 1,4-butanediol, 2-methyl-1,4-butanediol, 2-methyl-1,4-butanediamine, isobutene, itaconate, acetoin, acetone, isobutene, 1,5-diaminopentane, L-lactic acid, D-lactic acid, shikimic acid, mevalonate, polyhydroxybutyrate (PHB), isoprenoids, fatty acids, homoalanine, 4-aminobutyric acid (GABA), succinic acid, malic acid, citric acid, adipic acid, p-hydroxy-cinnamic acid, tetrahydrofuran, 3-methyl-tetrahydrofuran, gamma-butyrolactone, pyrrolidinone, n-methylpyrrolidone, aspartic acid, lysine, cadeverine, 2-ketoadipic acid, and/or S-adenosyl-methionine (SAM) from a suitable nitrogen rich biomass.

  10. Gallium nanoparticles colloids synthesis for UV bio-optical sensors

    Science.gov (United States)

    Nucciarelli, Flavio; Bravo, Iria; Vázquez, Luis; Lorenzo, Encarnación; Pau, Jose Luis

    2017-05-01

    A new method for the synthesis of colloidal gallium nanoparticles (Ga NPs) based on the thermal evaporation of Ga on an expendable aluminum zinc oxide (AZO) layer is presented here. The growth of AZO layers was investigated on different substrates at room temperature and 300 °C. By means of physical evaporation process, nanoparticles were deposited with a distribution ranging from 10 nm to 80 nm in diameter. A study of their endurance in acidic environment was carried out in order to assure the NPs shape and size stability during the etching process. Smaller particles start to disappear between 1h and 2h immersion time in a pH=1 solution, while bigger particles reduce their dimension. The NPs were dispersed in tetrahydrofuran (THF) organic solvent and optically characterized, showing strong UV absorption with a band centered at 280 nm. The colloids size distribution of as-evaporated samples was compared with the distribution obtained in droplets of the solution after drop-casting. By Dipole Discrete Approximation simulations, a close relationship between the UV absorption and the NPs with diameter smaller than 40 nm was found. Because of the gallium oxide (Ga1-xOx) outer shell that surrounds the Ga NPs, an enhancement of their hydrophobicity occurs. Hence, the low agglomeration state between NPs in tetrahydrofuran allows to obtain narrow absorption band in the optical spectrum.

  11. Synthetic oligomer analysis using atmospheric pressure photoionization mass spectrometry at different photon energies

    Energy Technology Data Exchange (ETDEWEB)

    Desmazières, Bernard [Global Bioenergies, 5 rue Henri Desbruyeres, 91030 Evry (France); Legros, Véronique [CNRS, UMR8587, Université d’Evry-Val-d’Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, F-91025 Evry (France); Giuliani, Alexandre [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette (France); UAR1008, CEPIA, INRA, Rue de la Geraudiere, F-44316 Nantes (France); Buchmann, William, E-mail: william.buchmann@univ-evry.fr [CNRS, UMR8587, Université d’Evry-Val-d’Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, F-91025 Evry (France)

    2014-01-15

    Graphical abstract: Atmospheric pressure photoIonization mass spectra of synthetic oligomers were recorded in the negative mode by varying the photon energy using synchrotron radiation. Photon energy required for an efficient ionization of the polymer was correlated to ionization potential of the solvent (for example 9.4 eV for tetrahydrofuran). -- Highlights: •Atmospheric pressure photoionization was performed using synchrotron radiation. •Photoionization of oligomers in THF with 10% CH{sub 2}Cl{sub 2} produces intact [M + Cl]{sup −} ions. •The photon energy required corresponds to ionization potential of the solvent. •Polymer distributions depend on source parameters such T °C and applied voltages. •Liquid chromatography was coupled to MS using an APPI interface for polymer analysis. -- Abstract: Atmospheric pressure photoionization (APPI) followed by mass spectrometric detection was used to ionize a variety of polymers: polyethylene glycol, polymethyl methacrylate, polystyrene, and polysiloxane. In most cases, whatever the polymer or the solvent used (dichloromethane, tetrahydrofuran, hexane, acetone or toluene), only negative ion mode produced intact ions such as chlorinated adducts, with no or few fragmentations, in contrast to the positive ion mode that frequently led to important in-source fragmentations. In addition, it was shown that optimal detection of polymer distributions require a fine tuning of other source parameters such as temperature and ion transfer voltage. Series of mass spectra were recorded in the negative mode, in various solvents (dichloromethane, tetrahydrofuran, hexane, toluene, and acetone), by varying the photon energy from 8 eV up to 10.6 eV using synchrotron radiation. To these solvents, addition of a classical APPI dopant (toluene or acetone) was not necessary. Courtesy of the synchrotron radiation, it was demonstrated that the photon energy required for an efficient ionization of the polymer was correlated to the

  12. Photosensitizers for photodynamic therapy: One-pot heterogeneous catalytic transfer reduction of porphyrins

    Directory of Open Access Journals (Sweden)

    Amadeu F Brigas

    2011-01-01

    Full Text Available A number of new porphyrin-based photosensitizers have been developed for Photodynamic Therapy (PDT in recent years. Chlorins, which are a reduced form of porphyrins, show better potential of application since they have a stronger absorption band on the red region of the visible spectrum and, hence, a deeper penetration into tissues. We found that by using heterogeneous catalytic transfer reduction (CTR, meso-tetraphenylporphyrin (TPP could be hydrogenated, although in modest yields, to meso-tetraphenylchlorin (TPC in a single reaction step. Best reaction conditions were attained using formic acid or sodium phosphinate/water as hydrogen donors, tetrahydrofuran (THF or toluene as solvent and 10% palladium on charcoal as catalyst.

  13. Changing the Mechanism for CO2 Hydrogenation Using Solvent-Dependent Thermodynamics.

    Science.gov (United States)

    Burgess, Samantha A; Appel, Aaron M; Linehan, John C; Wiedner, Eric S

    2017-11-20

    A critical scientific challenge for utilization of CO2 is the development of catalyst systems that function in water and use inexpensive and environmentally friendly reagents. We have used thermodynamic insights to predict and demonstrate that the HCoI (dmpe)2 catalyst system, previously described for use in organic solvents, can hydrogenate CO2 to formate in water with bicarbonate as the only added reagent. Replacing tetrahydrofuran as the solvent with water changes the mechanism for catalysis by altering the thermodynamics for hydride transfer to CO2 from a key dihydride intermediate. The need for a strong organic base was eliminated by performing catalysis in water owing to the change in mechanism. These studies demonstrate that the solvent plays a pivotal role in determining the reaction thermodynamics and thereby catalytic mechanism and activity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Incorporation of pyrene in polypyrrole/polystyrene magnetic beads.

    Science.gov (United States)

    Głowala, Paulina; Budniak, Adam; Krug, Pamela; Wysocka, Barbara; Berbeć, Sylwia; Dec, Robert; Dołęga, Izabela; Kacprzak, Kamil; Wojciechowski, Jarosław; Kawałko, Jakub; Kępka, Paweł; Kępińska, Daria; Kijewska, Krystyna; Mazur, Maciej

    2014-10-15

    Pyrene, a fluorescent dye, was incorporated into polystyrene particles coated with polypyrrole. The incorporation was achieved by treating the polypyrrole/polystyrene (PPy/PS) beads in a tetrahydrofuran (THF) solution of the pyrene fluorophore followed by rinsing with methanol. The polystyrene cores of the beads swell in THF, allowing penetration of pyrene molecules into the polystyrene structure. The addition of methanol causes contraction of the swollen polystyrene, which encapsulates the dye molecules inside the beads. It is shown that the polypyrrole coating is permeable with respect to both the dye and the solvent, allowing the transport of molecules between the polystyrene cores and the contacting solution. The polypyrrole adlayer can be used as a matrix for the incorporation of magnetic nanoparticles. Embedded particles provide magnetic functionality to the PPy/PS beads. It is demonstrated that the pyrene-loaded beads can be manipulated with an external magnetic field. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Development and Characterization of Novel Polyurethane Films Impregnated with Tolfenamic Acid for Therapeutic Applications

    Science.gov (United States)

    Sheraz, Muhammad Ali; Rehman, Ihtesham ur

    2013-01-01

    The present study deals with the preparation of polyurethane (PU) films impregnated with a nonsteroidal anti-inflammatory drug, tolfenamic acid (TA). Solvent evaporation technique has been employed for the preparation of TA-PU films in two different ratios of 1 : 2 and 1 : 5 in Tetrahydrofuran (THF) or THF-ethanol mixtures. The prepared films were characterized using X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and release studies. The results indicate transformation of crystalline TA to its amorphous form. The degree of crystallinity changes both by increasing the polymer concentration and solvent used for the film preparations. The release profiles of TA were also found to be affected, showing a decrease from approximately 50% to 25% from 1 : 2 to 1 : 5 ratios, respectively. PMID:24073394

  16. Tyrosinase Inhibition Type of Isolated Compounds Obtained from Pachyrhizus erosus

    Directory of Open Access Journals (Sweden)

    Endang Lukitaningsih

    2013-12-01

    Full Text Available In Indonesia, Bengkoang (Phacyrhizus erosus have been used as one of cosmetics especially as sun screening and skin whitening materials. Six active compounds in Bengkoang with antioxidant and skin whitening activities have been isolated, namely daidzein, daidzin, genistin, (8,9-furanyl-pterocarpan-3-ol, 4-(2-(furane-2-ylethyl-2-methyl-2,5-dihydro-furane-3-carbaldehyde and 2-butoxy-2,5-bis(hydroxymethyl-tetrahydrofurane-3,4-diol. According to literatures, the type of their tyrosinase inhibitory activity has not yet reported. The determination of whitening activity of each compound was evaluated by the evaluation of Lineweaver-Burk plot. The result showed that five compounds had competitive inhibitory activity and 8,9-furanyl-pterocarpan-3-ol showed a non-competitive inhibition.

  17. Understanding the Lewis Acidity of Co(II) Sites on a Silica Surface.

    Science.gov (United States)

    Estes, Deven P; Cook, Amanda K; Lam, Erwin; Wong, Louise; Copéret, Christophe

    2017-07-17

    Heterogeneous catalysts consisting of isolated transition-metal sites dispersed on the surface of metal oxide supports are commonly used in the chemical industry. Often their reactivity relies on the Lewis acidity of the active sites on the surface of the catalyst. A recent report from our group showed that silica-supported Co(II) sites, prepared via surface organometallic chemistry, are active in both alkene hydrogenation and alkane dehydrogenation, possibly linked to the Lewis acidity of the Co(II) sites. Here we use molecular probes and analogues to both qualitatively and quantitatively model the Lewis acidity of the surface sites. Some sites do not bind probe molecules like carbon monoxide, tetrahydrofuran, and olefins, while others exhibit a continuum of Lewis acidities. This is consistent with variations in the coordination environment of Co. These results suggest that only the most Lewis acidic sites are involved in dehydrogenation and hydrogenation, consistent with catalyst poisoning studies.

  18. Viscoelastic, Spectroscopic and Microscopic Study of the Photo Irradiation Effect on the Stability of PVC in the Presence of Sulfamethoxazole Schiff’s Bases

    Directory of Open Access Journals (Sweden)

    Emad Yousif

    2015-11-01

    Full Text Available The photostabilization of poly(vinyl chloride (PVC films having five Schiff’s bases derived from sulphamethoxazole has been investigated. The casting method was used to produce PVC films containing sulphamethoxazoles (0.5% by weight, in tetrahydrofuran. The photostabilization activities of five additives were determined by monitoring the hydroxyl, polyene and carbonyl indices with irradiation time. In addition, the quantum yield of the chain scission (Φcs and the changes in viscosity average molecular weight of PVC films containing Schiff’s basses were evaluated with irradiation time. The rate of photostabilization for PVC films in the presence of five Schiff’s base additives was found to be the highest in the case of 2-hydroxybenzylidene derivative and the lowest in the unsubstituted benzylidene derivative. Several mechanisms have been suggested to explain the photostabilization of PVC in the presence of Schiff’s bases that mainly act as UV absorbers and radical scavengers for photostabilizers.

  19. Heronapyrrole D: A case of co-inspiration of natural product biosynthesis, total synthesis and biodiscovery

    Directory of Open Access Journals (Sweden)

    Jens Schmidt

    2014-05-01

    Full Text Available The heronapyrroles A–C have first been isolated from a marine-derived Streptomyces sp. (CMB-0423 in 2010. Structurally, these natural products feature an unusual nitropyrrole system to which a partially oxidized farnesyl chain is attached. The varying degree of oxidation of the sesquiterpenyl subunit in heronapyrroles A–C provoked the hypothesis that there might exist other hitherto unidentified metabolites. On biosynthetic grounds a mono-tetrahydrofuran-diol named heronapyrrole D appeared a possible candidate. We here describe a short asymmetric synthesis of heronapyrrole D, its detection in cultivations of CMB-0423 and finally the evaluation of its antibacterial activity. We thus demonstrate that biosynthetic considerations and the joint effort of synthetic and natural product chemists can result in the identification of new members of a rare class of natural products.

  20. Nonlinear optical characterization of Disperse Orange 3

    Science.gov (United States)

    Derkowska-Zielinska, Beata; Fedus, Kamil; Wang, Hongzhen; Cassagne, Christophe; Boudebs, Georges

    2017-10-01

    The nonlinear optical responses of Disperse Orange 3 (DO3) dissolved in tetrahydrofuran (THF) with different concentrations were investigated by Z-scan D4σ technique employing 12 ps and 17 ps pulses of Nd:YAG laser at 532 nm and 1064 nm, respectively. The comparison of the experimental results at both wavelengths demonstrates the strong influence of the resonant phenomena related to the linear absorption on the nonlinear response at 532 nm. In particular, DO3 solution was found to exhibit negative resonant nonlinear refraction with negligible saturable and multi-photon absorption. Moreover, the competition between negative and positive nonlinear refractive indices (n2) of the solute and the solvent was observed at low concentrations. The linear dependence of n2 on the latter quantity allowed to estimate an effective second-order hyperpolarizability of DO3 molecule at 532 nm.

  1. Highly Sensitive and Selective Gas Sensor Using Hydrophilic and Hydrophobic Graphenes

    Science.gov (United States)

    Some, Surajit; Xu, Yang; Kim, Youngmin; Yoon, Yeoheung; Qin, Hongyi; Kulkarni, Atul; Kim, Taesung; Lee, Hyoyoung

    2013-06-01

    New hydrophilic 2D graphene oxide (GO) nanosheets with various oxygen functional groups were employed to maintain high sensitivity in highly unfavorable environments (extremely high humidity, strong acidic or basic). Novel one-headed polymer optical fiber sensor arrays using hydrophilic GO and hydrophobic reduced graphene oxide (rGO) were carefully designed, leading to the selective sensing of volatile organic gases for the first time. The two physically different surfaces of GO and rGO could provide the sensing ability to distinguish between tetrahydrofuran (THF) and dichloromethane (MC), respectively, which is the most challenging issue in the area of gas sensors. The eco-friendly physical properties of GO allowed for faster sensing and higher sensitivity when compared to previous results for rGO even under extreme environments of over 90% humidity, making it the best choice for an environmentally friendly gas sensor.

  2. Interstitial modification of palladium nanoparticles with boron atoms as a green catalyst for selective hydrogenation

    Science.gov (United States)

    Chan, Chun Wong Aaron; Mahadi, Abdul Hanif; Li, Molly Meng-Jung; Corbos, Elena Cristina; Tang, Chiu; Jones, Glenn; Kuo, Winson Chun Hsin; Cookson, James; Brown, Christopher Michael; Bishop, Peter Trenton; Tsang, Shik Chi Edman

    2014-12-01

    Lindlar catalysts comprising of palladium/calcium carbonate modified with lead acetate and quinoline are widely employed industrially for the partial hydrogenation of alkynes. However, their use is restricted, particularly for food, cosmetic and drug manufacture, due to the extremely toxic nature of lead, and the risk of its leaching from catalyst surface. In addition, the catalysts also exhibit poor selectivities in a number of cases. Here we report that a non-surface modification of palladium gives rise to the formation of an ultra-selective nanocatalyst. Boron atoms are found to take residence in palladium interstitial lattice sites with good chemical and thermal stability. This is favoured due to a strong host-guest electronic interaction when supported palladium nanoparticles are treated with a borane tetrahydrofuran solution. The adsorptive properties of palladium are modified by the subsurface boron atoms and display ultra-selectivity in a number of challenging alkyne hydrogenation reactions, which outclass the performance of Lindlar catalysts.

  3. 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.

  4. Devices and methods to detect and quantify trace gases

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D.; Robinson, Alex

    2016-05-03

    Sensing devices based on a surface acoustic wave ("SAW") device coated with an absorbent crystalline or amorphous layer for detecting at least one chemical analyte in a gaseous carrier. Methods for detecting the presence of a chemical analyte in a gaseous carrier using such devices are also disclosed. The sensing devices and methods for their use may be configured for sensing chemical analytes selected from the group consisting of water vapor, carbon dioxide, methanol, ethanol, carbon monoxide, nitric oxide, nitrous oxide, organic amines, organic compounds containing NO.sub.2 groups, halogenated hydrocarbons, acetone, hexane, toluene, isopropanol, alcohols, alkanes, alkenes, benzene, functionalized aromatics, ammonia (NH.sub.3), phosgene (COCl.sub.2), sulfur mustard, nerve agents, sulfur dioxide, tetrahydrofuran (THF) and methyltertbutyl ether (MTBE) and combinations thereof.

  5. Surfactant-free single-layer graphene in water.

    Science.gov (United States)

    Bepete, George; Anglaret, Eric; Ortolani, Luca; Morandi, Vittorio; Huang, Kai; Pénicaud, Alain; Drummond, Carlos

    2017-04-01

    Dispersing graphite in water to obtain true (single-layer) graphene in bulk quantity in a liquid has been an unreachable goal for materials scientists in the past decade. Similarly, a diagnostic tool to identify solubilized graphene in situ has been long awaited. Here we show that homogeneous stable dispersions of single-layer graphene (SLG) in water can be obtained by mixing graphenide (negatively charged graphene) solutions in tetrahydrofuran with degassed water and evaporating the organic solvent. In situ Raman spectroscopy of these aqueous dispersions shows all the expected characteristics of SLG. Transmission electron and atomic force microscopies on deposits confirm the single-layer character. The resulting additive-free stable water dispersions contain 400 m 2 l -1 of developed graphene surface. Films prepared from these dispersions exhibit a conductivity of up to 32 kS m -1 .

  6. Effective inhibition by beta-carotene of cellular DNA breaking induced by peroxynitrous acid.

    Science.gov (United States)

    Hiramoto, K; Tomiyama, S; Kikugawa, K

    1999-01-01

    Peroxynitrous acid synthesized by reaction of hydrogen peroxide and nitrite and generated from 3-morpholinosydononimine (SIN-1) induced cellular DNA breaking of human promyelocytic leukemia HL-60 cells in phosphate buffer (pH 7.5) as assessed by alkaline single cell gel electrophoresis (comet) assay and quantification of comet types. Ascorbate and Trolox inhibited cellular DNA breaking induced by peroxynitrous acid, but the concentrations of these antioxidants required for effective inhibition was about 50-fold higher than that of peroxynitrous acid. beta-Carotene protected DNA breaking by peroxynitrous acid in 20% tetrahydrofuran-phosphate buffer (pH 7.5) much more effectively than ascorbate and Trolox. The concentrations of beta-carotene required for effective inhibition was lower than the concentration of peroxynitrous acid.

  7. Study of the parameters solution blow spinning technique in the obtaining of mullite nanofibers; Estudo de parametros da tecnica de fiacao por sopro em solucao na obtencao de nanofibras de mulita

    Energy Technology Data Exchange (ETDEWEB)

    Severo, L.L.; Farias, R.M.C.; Menezes, R.R.; Santos, M.A., E-mail: lucasleite_14.1@hotmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

    2016-07-01

    The Solution Blow Spinning (SBS) technique which use aerodynamic forces and has a high production rate, was created for production of nanofiber with versatile way, such as electrospinning. Therefore, the objective is to analyze the process parameters in order to optimize the production of mullite nanofiber using the SBS technique to determine the influence of air pressure, the concentration of the polymer and ejection rate in the diameter of the fibers. For this, it was used PVC as polymer in spinning, tetrahydrofuran as the solvent, HCl as acidifying, aluminum nitrate nonahydrate and tetraethylorthosilicate as precursors of mullite. The nanofibers obtained were heat treated at 1100°C. From of XRD and SEM results, it was proved the achievement of mullite nanofiber, and STATISTICA 7 software revealed that only ejection rate and the concentration influence in the average diameters of the fibers. (author)

  8. Synthesis, characterization and stability of chitosan and poly(methyl methacrylate) grafted carbon nanotubes.

    Science.gov (United States)

    Carson, Laura; Hibbert, Kemar; Akindoju, Feyisayo; Johnson, Chevaun; Stewart, Melisa; Kelly-Brown, Cordella; Beharie, Gavannie; Fisher, Tavis; Stone, Julia; Stoddart, Dahlia; Oki, Aderemi; Neelgund, Gururaj M; Regisford, Gloria; Traisawatwong, Pasakorn; Zhou, Jianren; Luo, Zhiping

    2012-10-01

    The single walled carbon nanotubes (CNTs) were effectively functionalized through grafting with chitosan (CTS) and poly(methyl methacrylate) (PMMA). Prior to grafting reaction, the carboxylated SWNCTs (SWNCTs-COOH) were obtained by treating pristine CNTs with a mixture of 3:1 (v/v) H(2)SO(4) and HNO(3), and the successive treatment of SWNCTs-COOH with SOCl(2) yielded the acylated CNTs (CNTs-COCl). The functionalized derivatives of CNTs were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. Both CTS and PMMA grafted CNTs showed better dispersability in acetic acid and tetrahydrofuran, in addition to higher stability in solution. Published by Elsevier B.V.

  9. Simple Efficient Routes for the Preparation of Pyrazoleamines and Pyrazolopyrimidines: Regioselectivity of Pyrazoleamines Reactions with Bidentate Reagents

    Directory of Open Access Journals (Sweden)

    Moustafa Sherief Moustafa

    2016-06-01

    Full Text Available Simple and efficient routes for the preparation of 2-amino-5-phenyl-4,5-dihydrofuran-3-carbonitrile (12, 2-oxo-5-phenyl-tetrahydrofuran-3-carbonitrile (13 and the 3,5-diaminopyrazole derivative 2h were developed. The results of the reactivity profiles of 12 and 2h are reported and the previously investigated reaction of pyrazole-3,5-diamine (2b with acrylonitrile to yield compound (31, a N-1 acylation product, is currently justified by using X-ray crystallographic analysis. Taken together, the observation of alkenes and alkynes substitution when reacting with 3,5-diaminopyrazole derivative 2h is explained by the terminal electron withdrawing group. This pattern of substitution is attributed to involvement of sterically unhindered electrophiles primarily at the N-1 position. This work is licensed under a Creative Commons Attribution 4.0 International License.

  10. A Rapid Determination of Cinnarizine in Bulk and Pharmaceutical Dosage Form by LC

    Directory of Open Access Journals (Sweden)

    A. A. Heda

    2010-01-01

    Full Text Available A simple, selective, rapid and precise reverse phase high pressure liquid chromatographic method has been developed for the estimation of cinnarizine from pharmaceutical formulation. The method was developed using MICRA-NPS C18 (length×OD×ID =33×8.0×6.0 mm, 1.5 μm column with a mobile phase consisting of acetonitrile, triethylamine buffer (adjusted to pH 4.5 with 10% w/v potassium hydroxide and tetrahydrofuran in the ratio 30:66:4 respectively, at a flow rate of 0.5 mL/min. Wavelength was fixed at 253 nm. The developed method was validated for linearity, accuracy, precision, limit of detection and limit of quantitation. The proposed method can be used for the routine estimation of cinnarizine in pharmaceutical dosage form.

  11. Methyl 7,8-diacetoxy-11-oxo-5-(2-oxopyrrolidin-1-yl-7,9-epoxycyclopenta[4,5]pyrido[1,2-a]quinoline-10-carboxylate sesquihydrate

    Directory of Open Access Journals (Sweden)

    Atash V. Gurbanov

    2010-01-01

    Full Text Available The title compound, C26H28N2O9·1.5H2O, the product of an acid-catalysed Wagner–Meerwein skeletal rearrangement, crystallizes as a sesquihydrate with the O atom of one of the two independent water molecules occupying a special position on a twofold axis. The organic molecule comprises a fused pentacyclic system containing two five-membered rings (cyclopentane and tetrahydrofuran and three six-membered rings (piperidinone, tetrahydropyridine and benzene. The five-membered rings have the usual envelope conformations, and the central six-membered piperidinone and tetrahydropyridine rings adopt boat and sofa conformations, respectively. In the crystal, there are three independent O—H...O hydrogen bonds, which link the organic molecules and water molecules into complex two-tier layers parallel to (001. The layers are further linked into a three-dimensional framework by attractive intermolecular carbonyl–carbonyl interactions.

  12. 4,5,7,8,17-Pentahydroxy-14,18-dimethyl-6-methylene-3,10-dioxapentacyclo[9.8.0.01,7.04,19.013,18]nonadec-14-ene-9,16-dione methanol solvate dihydrate

    Directory of Open Access Journals (Sweden)

    Chin Hoe Teh

    2009-04-01

    Full Text Available The title quassinoid compound, C20H24O9·CH3OH·2H2O, is a natural eurycomanone isolated from the roots of Eurycoma longifolia. The molecules contain a fused five-ring system, with one tetrahydrofuran ring adopting an envelope conformation, one tetrahydropyran-2-one ring in a screw boat conformation, one cyclohexenone ring in a half-chair conformation and two cyclohexane rings in chair conformations. Intramolecular C—H...O interactions generate S(5 ring motifs and an O—H...O interaction generates an S(7 ring motif. In the crystal, molecules are linked via intermolecular O—H...O interactions along the b axis and further stacked along a axis. The absolute configuration of the title compound was inferred from previously solved structures of its analogues.

  13. Photophysical, Photochemical, and BQ Quenching Properties of Zinc Phthalocyanines with Fused or Interrupted Extended Conjugation

    Directory of Open Access Journals (Sweden)

    Gülşah Gümrükçü

    2014-01-01

    Full Text Available The effects of substituents and solvents on the photophysical and photochemical parameters of zinc(II phthalocyanines containing four Schiff’s base substituents attached directly and through phenyleneoxy-bridges on peripheral positions are reported. The group effects on peripheral position and the continual and intermittent conjugation of the phthalocyanine molecules on the photophysical and photochemical properties are also investigated. General trends are described for photodegradation, singlet oxygen, and fluorescence quantum yields of these compounds in dimethylsulfoxide (DMSO, dimethylformamide (DMF, and tetrahydrofurane (THF. Among the different substituents, phthalocyanines with cinnamaldimine moieties (1c and 2c have the highest singlet oxygen quantum yields (ΦΔ and those with nitro groups (1a and 2a have the highest fluorescence quantum yields in all the solvents used. The fluorescence of the substituted zinc(II phthalocyanine complexes is effectively quenched by 1,4-benzoquinone (BQ in these solvents.

  14. Synthesis and characterization of near-IR absorbing metal-free and zinc(II phthalocyanines modified with aromatic azo groups

    Directory of Open Access Journals (Sweden)

    Mukaddes Özçeşmeci

    2015-05-01

    Full Text Available Metal-free and zinc(II phthalocyanine complexes bearing peripheral (E-4-((2-hydroxynaphthalen-1-yldiazenyl units have been synthesized. Novel phthalonitrile derivative required for the preparation of phthalocyanine complexes was prepared by coupling 4-aminophthalonitrile and 2-naphthol. The structures of these new compounds were characterized by using elemental analyses, proton nuclear magnetic resonance, fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, fluorescence spectroscopy and mass spectrometry. In the UV-Vis spectra a broad absorption band appears for phthalocyanine complexes at around 450–500 nm resulting from azo-group introduced onto the phthalocyanine ring. The photophysical properties of metal-free and zinc(II phthalocyanines were studied in tetrahydrofuran.

  15. Iron Oxide Arrays Prepared from Ferrocene- and Silsesquioxane-Containing Block Copolymers

    Directory of Open Access Journals (Sweden)

    Raita Goseki

    2012-01-01

    Full Text Available Arrays of iron oxides as precursors of iron clusters were prepared by oxygen plasma treatment of block copolymer microphase-separated nanostructures in thin films. Block copolymers composed of ferrocene-containing and silsesquioxane-containing polymethacrylate (PMAPOSS-b-PMAHFC were successfully prepared, with different molecular weights and compositions and narrow molecular weight distributions, by living anionic polymerization. The formed microphase-separated nanostructures in the bulk were characterized by wide- and small-angle X-ray scattering (WAXS and SAXS, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. Thin films were prepared from a solution of PMAPOSS-b-PMAHFC in tetrahydrofuran by spin coating onto silicon wafers. Fingerprint-type line nanostructures were formed in the PMAPOSS-b-PMAHFCs thin films after solvent annealing with carbon disulfide. Oxygen plasma treatment provided the final line arrays of iron oxides based on the formed nanostructural patterns.

  16. Reversible Deposition and Dissolution of Magnesium from Imidazolium-Based Ionic Liquids

    Directory of Open Access Journals (Sweden)

    QingSong Zhao

    2012-01-01

    Full Text Available The electrochemical performance of six imidazolium cation-based ionic liquids (ILs containing 0.3 mol L-1 Mg(CF3SO32 as the electrolytes for magnesium deposition-dissolution was examined by cyclic voltammogramms and constant current discharge-charge techniques. Scanning electron microscopy and energy dispersive X-ray spectroscopy measurements were conducted to characterize the morphologies and components of the deposits. The cathodic satiability of imidazolium cations can be improved by increasing the length of alkyls at the 1-position and introducing methyl group at the 2-position of the imidazolium cations. A reversible magnesium deposition-dissolution can be achieved at room temperature. After adding appreciate amount of tetrahydrofuran (THF organic solvent, the conductivity and the peak currents for Mg deposition and dissolution can be significantly improved. The potential polarization of deposition-dissolution process is decreased using Mg powder electrode.

  17. Manipulating the Morphology of P3HT–PCBM Bulk Heterojunction Blends with Solvent Vapor Annealing

    KAUST Repository

    Verploegen, Eric

    2012-10-23

    Using grazing incidence X-ray scattering, we observe the effects of solvent vapors upon the morphology of poly(3-hexylthiophene)-phenyl-C 61-butyric acid methyl ester (P3HT-PCBM) bulk heterojunction thin film blends in real time; allowing us to observe morphological rearrangements that occur during this process as a function of solvent. We detail the swelling of the P3HT crystallites upon the introduction of solvent and the resulting changes in the P3HT crystallite morphology. We also demonstrate the ability for tetrahydrofuran vapor to induce crystallinity in PCBM domains. Additionally, we measure the nanoscale phase segregated domain size as a function of solvent vapor annealing and correlate this to the changes observed in the crystallite morphology of each component. Finally, we discuss the implications of the morphological changes induced by solvent vapor annealing on the device properties of BHJ solar cells. © 2012 American Chemical Society.

  18. Photostabilizing Efficiency of PVC in the Presence of Schiff Bases as Photostabilizers

    Directory of Open Access Journals (Sweden)

    Emad Yousif

    2015-11-01

    Full Text Available The photostabilization of polyvinyl chloride (PVC films by Schiff bases was investigated. Polyvinyl chloride films containing 0.5 wt % Schiff bases were produced using the same casting method as that used for additive-free PVC films from tetrahydrofuran (THF solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl, polyene and hydroxyl indices with irradiation time. The changes in viscosity average molecular weight of PVC with irradiation time were also monitored using THF as a solvent. The quantum yield of chain scission (Φcs for the studied complexes in PVC was estimated to range between 4.72 and 8.99 × 10−8. According to the experimental results, several mechanisms were suggested, depending on the structure of the additive. Ultra violet (UV absorption, peroxide decomposition and radical scavenging were suggested as the photostabilizing mechanisms.

  19. Effects of dope extrusion rate on the morphology and gas separation performance of asymmetric polysulfone hollow fiber membranes for O2/N2 separation

    Directory of Open Access Journals (Sweden)

    Ahmad Fausi Ismail

    2002-11-01

    Full Text Available The objective of this study was to investigate the influence of dope extrusion rates on morphology and gas separation performance of asymmetric polysulfone hollow fiber membranes. Asymmetric polysulfone hollow fiber membranes for gas separation were prepared from a solution consisting of 26.0 wt. % of polysulfone, 30.4 wt. % of N, N-dimethylacetamide, 30.4 wt. % of tetrahydrofuran and 13.2 wt. % ethanol. The dry/wet phase separation process was applied to a dry/wet spinning process. Fibers were spun at various dope extrusion rates (DER ranging from 1.5 - 3.0 cm3/min and hence at different levels of shear. The results suggest that as the dope extrusion rate is increased, the selectivity will increase until a critical level of shear is reached, beyond which the membrane performance deteriorates. Pressure-normalized-fluxes and selectivities were evaluated by using pure oxygen and nitrogen as test gases.

  20. Direct transfer of graphene films for polyurethane substrate

    Energy Technology Data Exchange (ETDEWEB)

    Vilani, C.; Romani, E.C.; Larrudé, D.G. [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900 Rio de Janeiro, RJ (Brazil); Barbosa, Gelza M. [Diretoria de Sistemas de Armas da Marinha, Marinha do Brasil, 20010-00 Rio de Janeiro, RJ (Brazil); Freire, F.L., E-mail: lazaro@vdg.fis.puc-rio.br [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900 Rio de Janeiro, RJ (Brazil); Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro, RJ (Brazil)

    2015-11-30

    Highlights: • Graphene was prepared by CVD using copper foils as substrates. • Monolayer, bilayer and multilayer graphene were transferred to PU. • Samples were characterized by Raman and optical spectroscopies. • PU/monolayer graphene has transmittance around 80% in visible range. - Abstract: We have proposed the direct transfer of large-area graphene films grown by chemical vapor deposition to polymeric substrate by evaporating of solvents of polyurethane/tetrahydrofurane solution. The graphene films on polyurethane substrates were characterized by Raman spectroscopy, optical and atomic force microscopies and UV–vis spectroscopy measurements. The Raman spectra revealed that it is possible to transfer in a controlled manner monolayer, bilayer and multilayer graphene films over polyurethane substrate.

  1. The use of white-rot fungi as active biofilters

    Energy Technology Data Exchange (ETDEWEB)

    Braun-Luellemann, A.; Johannes, C.; Majcherczyk, A.; Huettermann, A. [Univ. Goettingen (Germany). Forstbotanisches Inst.

    1995-12-31

    White-rot fungi, growing on lignocellulosic substrates, have been successfully used as active organisms in biofilters. Filters using these fungi have a very high biological active surface area, allowing for high degrees of retention, a comparatively low pressure drop, and a high physical stability. The unspecific action of the extracellular enzymes of the white-rot fungi allows for the degradation of a wide variety of substances by the same organism. Degradation of several compounds in the gas phase by the white-rot fungi Trametes versicolor, Pleurotus ostreatus, Bjerkandera adusta, and Phanerochaete chrysosporium was tested. Among the aromatic solvents, styrene was the compound that was most readily degraded, followed by ethylbenzene, xylenes, and toluene. Tetrahydrofuran and dichloromethane were also degraded, whereas dioxane could not be attacked by fungi under the conditions used. Acrylonitrile and aniline were degraded very well, whereas pyridine was resistant to degradation. The process for removing styrene is now in the scaling-up stage.

  2. Control of Self-Assembly of Lithographically Patternable Block Copolymer Films

    Energy Technology Data Exchange (ETDEWEB)

    Black, C.T.; Bosworth, J.K.; Paik, M.Y.; Ruiz, R.; Schwartz, E.L.; Huang, J.Q.; Ko, A.W.; Smilgies, D.-M.; Ober, C.K.

    2008-07-22

    Poly({alpha}-methylstyrene)-block-poly(4-hydroxystyrene) acts as both a lithographic deep UV photoresist and a self-assembling material, making it ideal for patterning simultaneously by both top-down and bottom-up fabrication methods. Solvent vapor annealing improves the quality of the self-assembled patterns in this material without compromising its ability to function as a photoresist. The choice of solvent used for annealing allows for control of the self-assembled pattern morphology. Annealing in a nonselective solvent (tetrahydrofuran) results in parallel orientation of cylindrical domains, while a selective solvent (acetone) leads to formation of a trapped spherical morphology. Finally, we have self-assembled both cylindrical and spherical phases within lithographically patterned features, demonstrating the ability to precisely control ordering. Observing the time evolution of switching from cylindrical to spherical morphology within these features provides clues to the mechanism of ordering by selective solvent.

  3. Control of Self-Assembly of Lithographically Patternable Block Copolymer Films

    Energy Technology Data Exchange (ETDEWEB)

    Bosworth, Joan K.; Paik, Marvin Y.; Ruiz, Ricardo; Schwartz, Evan L.; Huang, Jenny Q.; Ko, Albert W.; Smilgies, Detlef-M.; Black, Charles T.; Ober, Christopher K. (Cornell); (IBM)

    2008-08-06

    Poly({alpha}-methylstyrene)-block-poly(4-hydroxystyrene) acts as both a lithographic deep UV photoresist and a self-assembling material, making it ideal for patterning simultaneously by both top-down and bottom-up fabrication methods. Solvent vapor annealing improves the quality of the self-assembled patterns in this material without compromising its ability to function as a photoresist. The choice of solvent used for annealing allows for control of the self-assembled pattern morphology. Annealing in a nonselective solvent (tetrahydrofuran) results in parallel orientation of cylindrical domains, while a selective solvent (acetone) leads to formation of a trapped spherical morphology. Finally, we have self-assembled both cylindrical and spherical phases within lithographically patterned features, demonstrating the ability to precisely control ordering. Observing the time evolution of switching from cylindrical to spherical morphology within these features provides clues to the mechanism of ordering by selective solvent.

  4. Nanostructured oxygen sensor--using micelles to incorporate a hydrophobic platinum porphyrin.

    Directory of Open Access Journals (Sweden)

    Fengyu Su

    Full Text Available Hydrophobic platinum(II-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl-porphyrin (PtTFPP was physically incorporated into micelles formed from poly(ε-caprolactone-block-poly(ethylene glycol to enable the application of PtTFPP in aqueous solution. Micelles were characterized using dynamic light scattering (DLS and atomic force microscopy (AFM to show an average diameter of about 140 nm. PtTFPP showed higher quantum efficiency in micellar solution than in tetrahydrofuran (THF and dichloromethane (CH₂Cl₂. PtTFPP in micelles also exhibited higher photostability than that of PtTFPP suspended in water. PtTFPP in micelles exhibited good oxygen sensitivity and response time. This study provided an efficient approach to enable the application of hydrophobic oxygen sensors in a biological environment.

  5. Synthesis of hollow silver spheres using poly-(styrene-methyl acrylic acid) as templates in the presence of sodium polyacrylate

    Science.gov (United States)

    Wang, Aili; Yin, Hengbo; Ge, Chen; Ren, Min; Liu, Yumin; Jiang, Tingshun

    2010-02-01

    Hollow silver spheres were successfully prepared by reducing AgNO 3 with ascorbic acid and using negatively charged poly-(styrene-methyl acrylic acid) (PSA) spheres as templates in the presence of sodium polyacrylate as a stabilizer. Firstly, silver cations adsorbed on the surface of PSA spheres via electrostatic attraction between the carboxyl groups and silver cations were reduced in situ by ascorbic acid. The silver nanoparticles deposited on the surface of PSA spheres served as seeds for the further growth of silver shells. After that, extra amount of AgNO 3 and ascorbic acid solutions were added to form PSA/Ag composites with thick silver shells. In order to obtain compact silver shells, the as-prepared PSA/Ag composites were heated at 150 °C for 3 h. Then hollow silver spheres were prepared by dissolving PSA templates with tetrahydrofuran.

  6. Effect of porogenic solvent on selective performance of molecularly imprinted polymer for quercetin

    Directory of Open Access Journals (Sweden)

    Xingliang Song

    2009-09-01

    Full Text Available Molecularly imprinted polymers (MIP's for quercetin were successfully synthesized by a thermal polymerization method using quercetin as template molecule, acrylamide as functional monomer and ethylene glycol dimethacrylate as cross-linker in the presence of four different porogenic solvents: 1,4-dioxane, tetrahydrofuran (THF, acetone, and acetonitrile. The selective performance of obtained MIP's was evaluated through HPLC analysis. The results indicated that the MIP obtained in THF showed the highest capacity and selectivity. The Scatchard method also supported HPLC results. The results were interpreted by computational quantum chemical analysis through Onsager self-consistent reaction field (SCRF technique in term of stabilization energy. It was also found that the amount of porogenic solvent used had impact on the adsorption effectiveness of MIP's.

  7. Determination of donepezil in serum samples using molecularly imprinted polymer nanoparticles followed by high-performance liquid chromatography with ultraviolet detection.

    Science.gov (United States)

    Khansari, Mehdi Rajabnia; Bikloo, Shahrzad; Shahreza, Sara

    2016-03-01

    A molecularly imprinted polymer designed for the selective extraction of donepezil from serum samples was synthesized using a noncovalent molecular imprinting approach. The molecularly imprinted polymer was evaluated chromatographically and then its affinity for donepezil was confirmed by solid-phase extraction. The optimal conditions for solid-phase extraction were provided by cartridge conditioning using acidified water purified from a Milli-Q system, sample loading under basic aqueous conditions, clean-up using acetonitrile, and elution with methanol/tetrahydrofuran. Desirable molecular recognition properties of the molecularly imprinted polymer led to good donepezil recoveries (90-102%). The data indicated that the imprinted polymer has a perfect selectivity and affinity for donepezil and could be used for selective extraction and analysis of donepezil in human serum. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Antioxidant Properties of Pyroligneous Acid Obtained by Thermochemical Conversion of Schisandra chinensis Baill

    Directory of Open Access Journals (Sweden)

    Chunhui Ma

    2014-12-01

    Full Text Available Sustainable development of renewable resources is a major challenge globally. Biomass is an important renewable energy source and an alternative to fossil fuels. Pyrolysis of biomass is a promising method for simultaneous production of biochar, bio-oil, pyroligneous acid (PA, and gaseous fuels. The purpose of this study was to investigate the pyrolysis process and products yields of Schisandra chinensis fruits with different pyrolysis powers. The obtained PA was extracted with organic solvents, including ethyl formate, dichloromethane, methanol and tetrahydrofuran. The antioxidant activities, including the free radical scavenging activity and ferric reducing power, of the PA extracts were investigated. The synthetic antioxidants butylated hydroxyanisole and butylated hydroxytoluene were used as positive controls. A dichloromethane extract of PA showed excellent antioxidant properties compared to the other extracts. The chemical compositions of the PA extracts were determined by GC-MS, and further proved that the dichloromethane extract had the best antioxidant characteristics among the extracts tested.

  9. Desenvolvimento e validação de método espectrofotométrico para determinação de corante à base de luteína adicionado em iogurte desnatado

    Directory of Open Access Journals (Sweden)

    Ana Augusta Odorissi Xavier

    2012-01-01

    Full Text Available A simple analytical method for extraction and quantification of lutein colorant added to yogurt was developed and validated. The method allowed complete extraction of carotenoids using tetrahydrofuran in vortex, followed by centrifugation, partition to diethyl ether/petroleum ether, and drying. The carotenoids dissolved in ethanol were quantified by UV-Vis spectrophotometry. This method showed linearity in the range tested (1.41-13.42 µg g-1, limits of detection and quantification of 0.42 and 1.28 µg g-1, respectively, low relative standard deviation (3.4% and recovery ranging from 95 to 103%. The method proved reliable for quantification of lutein added to yogurt.

  10. The effect on poly (ethylene oxide) / poly (vinyl chloride) / polyaniline (PAni) films by ethylene dimethacrylate as surface modifier: electrical conductivity and characterization

    Science.gov (United States)

    Yazid, M. I. M.; Ghani, S. A.; Osman, A. F.; Din, S. H. M.; Jin, T. S.

    2017-10-01

    In this paper, the electrical conductivity and the characterizations of poly (ethylene oxide) / poly (vinyl chloride) / polyaniline (PEO/PVC/PAni) films with and without the presence of Ethylene Dimethacrylate (EDMA) were investigated. The films were prepared using solution casting method using tetrahydrofuran as the solvent. The results indicated that the electrical conductivity of PEO/PVC/PAni films increased as the PAni loadings increased while PEO/PVC/PAni films with EDMA showed higher electrical conductivity than PEO/PVC/PAni films. PEO/PVC/PAni films with EDMA showed a value as high as 0.68 × 10-4 S/mm as it enhanced the interfacial adhesion between the matrix and the filler as proved by the SEM morphology. Meanwhile, the FTIR analysis confirmed there are no new chemical bonding occurred with the introduction of EDMA into the films.

  11. Recent advancements on the use of 2-methyltetrahydrofuran in organometallic chemistry.

    Science.gov (United States)

    Monticelli, Serena; Castoldi, Laura; Murgia, Irene; Senatore, Raffaele; Mazzeo, Eugenia; Wackerlig, Judith; Urban, Ernst; Langer, Thierry; Pace, Vittorio

    2017-01-01

    Since the introduction of 2-methyltetrahydrofuran as an useful alternative to the classical tetrahydrofuran, there has been a continuous interest in the synthetic community operating at academic and industrial towards it. In particular, the much higher stability that basic organometallic reagents display in 2-methyltetrahydrofuran makes it suitable for processes involving such sensitive species including asymmetric transformations. The easy formation of an azeotropic mixture with water, the substantial immiscibility with water, and the fact it derives from natural sources (corncobs or bagasse), allow to consider it in agreement with the Anastas' Geen Chemistry principles. In this minireview, selected examples of its employment in organometallic transformations ranging from carbanions to radical and transition metal-catalyzed processes are provided.

  12. Facile and efficient one-pot synthesis of 2-arylbenzoxazoles using hydrogen tetrachloroaurate as catalyst under oxygen atmosphere*

    Science.gov (United States)

    Liu, Yun-kui; Mao, Da-jie; Lou, Shao-jie; Qian, Jian-qiang; Xu, Zhen-yuan

    2009-01-01

    In this paper, we presented a novel method for the facile and efficient one-pot synthesis of 2-arylbenzoxazoles, which were directly synthesized from 2-aminophenol and aldehydes catalyzed by hydrogen tetrachloroaurate (HAuCl4·4H2O) under an oxygen atmosphere with anhydrous tetrahydrofuran (THF) as solvent or in solvent-free condition. The results show that this method could bring excellent yields as high as 96%. THF was proven to be the best choice among several solvents screened and the reaction was tolerated with a variety of aromatic aldehydes possessing electron-donating or withdrawing groups. The advantages of the present method lie in catalytic process using economic and environmentally benign dioxygen as oxidant. PMID:19489113

  13. Selective cloud point extraction and preconcentration of trace amounts of silver as a dithizone complex prior to flame atomic absorption spectrometric determination

    Energy Technology Data Exchange (ETDEWEB)

    Manzoori, Jamshid L.; Karim-Nezhad, Ghasem

    2003-05-19

    Dithizone (diphenylthiocarbazone) was used as a complexing agent in cloud point extraction for the first time and applied for selective preconcentration of trace amounts of silver. The analyte in the initial aqueous solution was acidified with sulfuric acid (pH<1) and Triton X-114 was added as a surfactant. After phase separation, based on the cloud point separation of the mixture, the surfactant rich phase was diluted with tetrahydrofuran (THF) and the analyte determined in the enriched solution by flame atomic absorption spectrometry. After optimization of the complexation and extraction conditions, a preconcentration factor of 43 was obtained for only 10 ml of sample. The analytical curve was linear in the range of 3-200 ng ml{sup -1} and the limit of detection was 0.56 ng ml{sup -1}. The proposed method was applied to the determination of silver in water samples.

  14. Aerosol-OT micelles in Sephadex gels for concentrating metal-dithizone chelates from water

    Energy Technology Data Exchange (ETDEWEB)

    Saitoh, Tohru [Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)]. E-mail: saitoh@numse.nagoya-u.ac.jp; Hattori, Kazuki [Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Hiraide, Masataka [Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2005-07-06

    Anionic surfactants, sodium dodecyl sulfate (SDS), and di-2-ethylhexyl sodium sulfosuccinate (Aerosol-OT, AOT), were incorporated into a hydrated macroreticular anion-exchanger such as a DEAE- or QAE-Sephadex A-25 gel. The observation of fluorescence spectra of N-phenyl-1-naphthlamine indicated the formation of the surfactant micelles in gels. The hydrophobicity of the micelles corresponded to octanol, tetrahydrofuran, or ethyl acetate. A hydrophobic chelating agent, dithizone (1,5-diphenylthiocarbazone), and its metal chelates were incorporated into the Sephadex gels. The complex formation with dithizone and the subsequent adsorption on Sephadex gels required 10 min. The metals collected in gels were desorbed with 8 M nitric acid. As a result of 300-fold concentrations, traces of heavy metal ions at ng l{sup -1} levels in river water were successfully determined by graphite-furnace atomic absorption spectrometry.

  15. Organonickel(II) complexes with anionic tridentate 1, 3-bis(azolylmethyl)phenyl ligands. synthesis, structural characterization and catalytic behavior

    Energy Technology Data Exchange (ETDEWEB)

    Hurtado, John; Rojas, Rene; Valderrama, Mauricio, E-mail: jmvalder@puc.cl [Departamento de Quimica Inorganica, Facultad de Quimica, Pontificia Universidad Catolica de Chile, Santiago (Chile); Ibanez, Andres [Centro para la Investigacion Interdisciplinaria Avanzada en Ciencia de los Materiales (CIMAT), Santiago (Chile); Froehlich, Roland [Organisch Chemisches Institut der Universitaet Muenster, Muenster (Germany)

    2011-09-15

    The reaction of 2-bromo-1,3-bis(bromomethyl)benzene with 3,5-dimethylpyrazole and {sup 1}H-indazole yields the tridentate ligands 2-bromo-1,3-bis(3,5-dimethylpirazol-1-ylmethyl)benzene (1) and 2-bromo-1,3-bis(indazol-2-ylmethyl)benzene (2). These compounds react with [Ni(cod)2] in tetrahydrofuran (thf) to form the oxidative addition complexes [NiBr{l_brace}1,3-bis(azolylmethyl)phenyl-N,C,N{r_brace}], azol 3,5-dimethylpyrazol (3), indazol (4), which were isolated in good yields as stable yellow solids and characterized by elemental analysis, Fourier-transform infrared spectroscopy (FTIR), mass spectroscopy and nuclear magnetic resonance (NMR). In addition, the molecular structures of 2 and 4 were determined by single-crystal X-ray diffraction analysis. Complex 4 was tested as a catalyst in ethylene polymerization reaction. (author)

  16. Unusual Closure of the Ten-Vertex Nido Cage via Alkylation: Regiospecific Synthesis of 3-Alkyl Derivatives of closo-1,2-C2B8H10.

    Science.gov (United States)

    Bakardjiev, Mario; Štíbr, Bohumil; Tok, Oleg L; Holub, Josef

    2018-01-05

    Alkylation of the [nido-5,6-R12C2B8H9]- anions (where R1 = H and Me) with alkyl halides (RX, where R = primary and secondary alkyls) in boiling tetrahydrofuran (THF) proceeds via unusual H2 elimination, followed by cage closure to give a series of the neutral closo-1,2-R12C2B8H7-3-R derivatives in ∼70-80% yields. In contrast, treatment of the unsubstituted [nido-5,6-C2B8H11]- anion with tert-butyl bromide (t-BuBr) led to the formation of the parent closo-1,2-C2B8H10 in >85% yield. The constitution of all compounds isolated has been confirmed unambiguously by multinuclear (11B, 1H, and 13C) nuclear magnetic resonance measurements and α-shift correlation assessments.

  17. Synthesis, characterisation and antimicrobial-activity of 3-thio-1,5-dihydro-2,4,3-benzodioxaphosphepin-3-amino acid esters

    Directory of Open Access Journals (Sweden)

    Chinthaparthi Radha Rani

    2011-01-01

    Full Text Available A new series of 3-thio-1,5-dihydro-2,4,3-benzodioxaphosphepin-3-amino acid esters (4a-k were synthesized by treating different amino acid ester hydrochlorides (3a-k with phosphorus monochloride intermediate (2 which was previously formed in situ from 1,2-phenylenedimethanol (1 and thiophosphoryl chloride in the presence of triethylamine in dry tetrahydrofuran (THF at 0-5 ºC to room temperature. The structures of the title compounds (4a-k were established by analytical, IR, NMR (1H, 13C and 31P and mass spectra, and they have been screened for their antimicrobial activity. They exhibited significant antibacterial, and antifungal activity.

  18. Copper(I) chloride: a simple salt for enhancement of polystyrene cationization in matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Kéki, S; Deák, G; Zsuga, M

    2001-01-01

    The possibility of using copper(I) chloride as a doping salt to enhance the cationization of polystyrene in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was investigated. It was shown that copper(I) chloride possesses sufficient solubility in tetrahydrofuran. The parameters of the MALDI mass spectra of different polystyrene samples, such as the number-average (M(n)) and mass-average (M(w)) molecular mass values, obtained by copper(I) cationization were compared with those obtained by means of silver(I) cationization, and good agreement was found. It was also shown that application of copper(I) chloride as a doping salt, and dithranol as a matrix, ensured good MALDI mass spectra of the sample spots even after storage for 1 month. Copyright 2001 John Wiley & Sons, Ltd.

  19. Comparison of the activities of fine-particle size catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Stohl, F.V.; Diegert, K.V.; Goodnow, D.C.

    1994-12-31

    The objectives of Sandia`s fine-particle size catalyst testing project are to evaluate and compare the activities of the fine-particle size catalysts being developed in DOE/PETCs Advanced Research Coal Liquefaction Program by using standard coal liquefaction test procedures. The standard procedures use Blind Canyon coal, phenanthrene as the reaction solvent, and a factorial experimental design with temperatures from 350{degrees}C to 400{degrees}C, reaction times from 20 to 60 minutes, and catalyst loadings up to 1 wt%. Catalytic activity is measured in terms of tetrahydrofuran conversion, heptane conversion, the amount of 9,10-dihydrophenanthrene in the product, and the gas yield. Several catalysts have been evaluated including a commercially available pyrite, a sulfated iron oxide from the University of Pittsburgh, and several preparations of 6-line ferrihydrites from Pacific Northwest Laboratories. Results have demonstrated that significant differences in activity can be detected among these catalysts.

  20. Effect of Polymer Concentration, Rotational Speed, and Solvent Mixture on Fiber Formation Using Forcespinning®

    Directory of Open Access Journals (Sweden)

    Nancy Obregon

    2016-06-01

    Full Text Available Polycaprolactone (PCL fibers were produced using Forcespinning® (FS. The effects of PCL concentration, solvent mixture, and the spinneret rotational speed on fiber formation were evaluated. The concentration of the polymer in the solvents was a critical determinant of the solution viscosity. Lower PCL concentrations resulted in low solution viscosities with a correspondingly low fiber production rate with many beads. Bead-free fibers with high production rate and uniform fiber diameter distribution were obtained from the optimum PCL concentration (i.e., 12.5 wt% with tetrahydrofuran (THF as the solvent. The addition of N, N-dimethylformamide (DMF to the THF solvent promoted the gradual formation of beads, split fibers, and generally affected the distribution of fiber diameters. The crystallinity of PCL fibers was also affected by the processing conditions, spinning speed, and solvent mixture.

  1. Optical signatures of bulk and solutions of KC{sub 8} and KC{sub 24}

    Energy Technology Data Exchange (ETDEWEB)

    Tristant, Damien [CEMES-CNRS, UPR-8011, Université Fédérale de Toulouse-Midi-Pyrénées, 29 rue Jeanne Marvig, BP 94347 Toulouse, Cedex 4 (France); LPCNO, UMR-5215 CNRS, INSA, Université Fédérale de Toulouse-Midi-Pyrénées, Université de Toulouse, 135 Avenue de Rangueil, 31077 Toulouse (France); Wang, Yu; Pénicaud, Alain [CNRS, CRPP, UPR-8641, Université Bordeaux 1, F-33600 Pessac (France); Gerber, Iann [LPCNO, UMR-5215 CNRS, INSA, Université Fédérale de Toulouse-Midi-Pyrénées, Université de Toulouse, 135 Avenue de Rangueil, 31077 Toulouse (France); Monthioux, Marc; Puech, Pascal, E-mail: Pascal.Puech@cemes.fr [CEMES-CNRS, UPR-8011, Université Fédérale de Toulouse-Midi-Pyrénées, 29 rue Jeanne Marvig, BP 94347 Toulouse, Cedex 4 (France)

    2015-07-28

    We first performed an analysis of the shape of the Raman features of potassium-intercalated graphite at stage 1 (KC{sub 8} GIC) and 2 (KC{sub 24} GIC), respectively. By varying the excitation energy from ultraviolet to infrared, we observed a sign change of the Fano coupling factor below and above the optical transition related to the shift of the Fermi level which was determined from first principle calculations. This behavior is explained by a sign change in the Raman scattering amplitude of the electronic continuum. The GICs were then dissolved in two different solvents (N-Methyl-2-pyrrolidone and tetrahydrofuran), and the absorbance of the graphenide solutions obtained was measured in the UV range. Two peaks were observed which correspond to the maximum of the computed imaginary part of the optical index.

  2. Nanotextured Morphology of Poly(methyl methacrylate and Ultraviolet Curable Poly(urethane acrylate Blends via Phase Separation

    Directory of Open Access Journals (Sweden)

    Ju-Hyung Kim

    2015-01-01

    Full Text Available Domain structures of spin-coated immiscible poly(methyl methacrylate (PMMA and ultraviolet (UV curable poly(urethane acrylate (PUA blends were studied using atomic force microscopy (AFM. Spin casting the PMMA/PUA blends in propylene glycol monomethyl ether acetate (PGMEA was accompanied with phase separation, and PUA was subsequently cross-linked under UV radiation. Selective dissolution of PMMA in the phase-separated films was feasible using tetrahydrofuran (THF solvent after the UV curing process, because the cured PUA material is highly stable against THF. Morphology of phase-separated structure, including domain size and height, could be controlled by varying total concentration of the blended solution, and various nanoscale features such as island-like and hole-like structures were achieved by changing weight ratio of the two immiscible polymers.

  3. Tuning the self-assembly of oligothiophenes on chemical vapor deposition graphene: effect of functional group, solvent, and substrate.

    Science.gov (United States)

    Sun, Xiuling; Mu, Youbing; Zhang, Jia; Wang, Xiaona; Hu, Pingan; Wan, Xiaobo; Guo, Zongxia; Lei, Shengbin

    2014-07-01

    Tuning and characterizing the interfacial structure of organic semiconductors on graphene is essential for graphene-based devices. Regulation of the supramolecular assembling structure of oligothiophenes on graphene by changing functional groups attached to the backbone of oligothiophenes is described and the assembling behavior is compared with that on the basal plane of highly oriented pyrolytic graphite. It reveals that terminal functional groups attached to the conjugated backbone of oligothiophene can entirely change the assembling structures. Significant solvent and substrate effects have also been confirmed by comparing the assembling structures of oligothiophenes deposited from tetrahydrofuran, 1,2,4-trichlorobenzene, and octanoic acid onto graphene and graphite. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Reaction of lithium diethylamide with an alkyl bromide and alkyl benzenesulfonate: origins of alkylation, elimination, and sulfonation.

    Science.gov (United States)

    Gupta, Lekha; Ramírez, Antonio; Collum, David B

    2010-12-17

    A combination of NMR, kinetic, and computational methods are used to examine reactions of lithium diethylamide in tetrahydrofuran (THF) with n-dodecyl bromide and n-octyl benzenesulfonate. The alkyl bromide undergoes competitive S(N)2 substitution and E2 elimination in proportions independent of all concentrations except for a minor medium effect. Rate studies show that both reactions occur via trisolvated-monomer-based transition structures. The alkyl benzenesulfonate undergoes competitive S(N)2 substitution (minor) and N-sulfonation (major) with N-sulfonation promoted at low THF concentrations. The S(N)2 substitution is shown to proceed via a disolvated monomer suggested computationally to involve a cyclic transition structure. The dominant N-sulfonation follows a disolvated-dimer-based transition structure suggested computationally to be a bicyclo[3.1.1] form. The differing THF and lithium diethylamide orders for the two reactions explain the observed concentration-dependent chemoselectivities.

  5. Preparation of Two-Layer Anion-Exchange Poly(ethersulfone Based Membrane: Effect of Surface Modification

    Directory of Open Access Journals (Sweden)

    Lucie Zarybnicka

    2016-01-01

    Full Text Available The present work deals with the surface modification of a commercial microfiltration poly(ethersulfone membrane by graft polymerization technique. Poly(styrene-co-divinylbenzene-co-4-vinylbenzylchloride surface layer was covalently attached onto the poly(ethersulfone support layer to improve the membrane electrochemical properties. Followed by amination, a two-layer anion-exchange membrane was prepared. The effect of surface layer treatment using the extraction in various solvents on membrane morphological and electrochemical characteristics was studied. The membranes were tested from the point of view of water content, ion-exchange capacity, specific resistance, permselectivity, FT-IR spectroscopy, and SEM analysis. It was found that the two-layer anion-exchange membranes after the extraction using tetrahydrofuran or toluene exhibited smooth and porous surface layer, which resulted in improved ion-exchange capacity, electrical resistance, and permselectivity of the membranes.

  6. Theoretical Investigation of Solvation Effects on the Tautomerism of Maleic Hydrazide

    Directory of Open Access Journals (Sweden)

    Meisam Shabanian

    2012-01-01

    Full Text Available A DFT study is used to calculate structural data of tautomers of maleic hydrazide (MH in the gas phase and selected solvents such as benzene (non-polar solvent, tetrahydrofuran (polar aprotic solvent and methanol (protic solvent, dimethyl sulfoxide (polar aprotic solvent and water (protic solvent using PCM model. All tautomers are optimized at the B3LYP/6−31++G(d,p. The results show that the tautomer MH2except in methanol is more stable than the other tautomers but in methanol MH5 (Diol is more stable. In addition, stability of the tautomers in deferent solvents shows interesting results. Variation of dipole moments and NBO charges on atoms in the solvents were studied.

  7. A DFT study of solvation effects and NBO analysis on the tautomerism of 1-substituted hydantoin

    Directory of Open Access Journals (Sweden)

    Meisam Shabanian

    2016-09-01

    Full Text Available 1-Substituted hydantoins (1-SH have been known as a benefit intermediate for producing agricultural and pharmaceuticals. The effect of solvent polarity on the tautomeric equilibria of 1-substituted hydantoin ring is studied by the density functional theory calculation (B3LYP/6–31++G(d,p level for predominant tautomeric forms of hydantoin derivatives (1-NO2, 1-CF3, 1-Br, 1-H, 1-CHCH2, 1-OH, 1-CH3 in the gas phase and selected solvents (benzene (non-polar solvent, tetrahydrofuran (THF (polar aprotic solvent and water (protic solvent. For electron withdrawing and releasing derivatives in the gas phase and solution Hy1 forms is more stable and dominant form. In addition variation of dipole moments and charges on atoms in the solvents are studied.

  8. Highly efficient and enzymatic regioselective undecylenoylation of gastrodin in 2-methyltetrahydrofuran-containing systems.

    Directory of Open Access Journals (Sweden)

    Rongling Yang

    Full Text Available Highly efficient and regioselective acylation of pharmacologically interesting gastrodin with vinyl undecylenic acid has been firstly performed through an enzymatic approach. The highest catalytic activity and regioselectivity towards the acylation of 7'-hydroxyl of gastrodin was obtained with Pseudomonas cepacia lipase. In addition, it was observed the lipase displayed higher activity in the eco-friendly solvent 2-methyltetrahydrofuran-containing systems than in other organic solvents. In the co-solvent mixture of tetrahydrofuran and 2-methyltetrahydrofuran (3/1, v/v, the reaction rate was 60.6 mM/h, substrate conversion exceeded 99%, and 7'-regioselectivity was 93%. It was also interesting that the lipase-catalyzed acylation couldn't be influenced by the benzylic alcohol in gastrodin. However, pseudomonas cepacia lipase displayed different regioselectivity towards gastrodin and arbutin.

  9. Cellulose derivatives carrying triphenylamine (TPA) moieties: synthesis and electro-optical properties.

    Science.gov (United States)

    Qu, Jinqing; Liao, Wenbo; Chen, Huanqin; Masuda, Toshio

    2009-06-11

    A novel ethyl cellulose derivative [poly(1)] that carries triphenylamine moieties is synthesized with a moderate number-average molecular weight up to 78,200 in 85% yield by the reaction of 4-(diphenylamino)benzoic acid with the residual hydroxy group of ethyl cellulose. Poly(1) is soluble in common organic solvents including toluene, CHCl3, CH2Cl2, and tetrahydrofuran while insoluble in hexane, diethyl ether, and methanol. The polymer emits blue-green fluorescence with quantum yields up to 65% in CHCl3 and displays unique solvatochromism. The cyclic voltammograms of poly(1) indicate that the polymer carrying TPA moieties is electrochemically redox active. The onset temperature of weight loss of the poly(1) is about 177 degrees C according to thermogravimetric analysis in air.

  10. Nitric oxide inhibitory constituents from the barks of Cinnamomum cassia.

    Science.gov (United States)

    He, Shan; Zeng, Ke-Wu; Jiang, Yong; Tu, Peng-Fei

    2016-07-01

    Six new compounds including one γ-butyrolactone, cinncassin A (1), two tetrahydrofuran derivatives, cinncassins B and C (2, 3), two lignans, cinncassins D and E (4, 5), and one phenylpropanol glucoside, cinnacassoside D (6), together with 14 known lignans (7-20) were isolated from the barks of Cinnamomum cassia. The structures of 1-6 were elucidated by extensive 1D and 2D NMR spectroscopic data analysis as well as chemical methods, and the absolute configurations were established by experimental and calculated ECD data. The anti-inflammatory activities of the isolates were evaluated on nitric oxide (NO) production in lipopolysaccharide (LPS)-induced BV-2 microglial cells. Compounds 5, 7, 8, and 15 showed potent inhibition activities with IC50 values of 17.6, 17.7, 18.7, and 17.5μM, respectively. Copyright © 2016. Published by Elsevier B.V.

  11. The effect of moisture on the liquefaction of some Turkish coals in tetralin with microwave energy

    Energy Technology Data Exchange (ETDEWEB)

    Simsek, E.H.; Karaduman, A.; Togrul, T. [Ankara University, Ankara (Turkey). Dept. of Chemical Engineers

    2002-07-01

    The effect of the moisture content of coals, solvent/coal ratio, and the heating period by microwave energy on solubilization of Turkish coals (Bolu-Goynuk, Beypazari, Mugla-Yatagan, Tuncbilek, Aydin-Yeniceltek lignites, and Zonguldak coal) in tetralin has been investigated. The yields of tetrahydrofuran (THF) solubles and oils were increased with increasing moisture content of coals. When solvent/coal ratio increased from 2/1 to 4/1, the yield of oils increased. However, the yields of asphaltenes and preasphaltenes decreased. The yields of THF solubles and oils did not change considerably with reaction time. While the yields of asphaltenes and preasphaltenes decreased with reaction time at the value of 2/1 of solvent/coal ratio and increased with reaction time at the value of 4/1 of solvent/coal ratio, the yields are lower than at the value of 2/1 of solvent/coal ratio.

  12. Effect of preswelling on soxhlet and supercritical gas extraction of a Turkish lignite

    Energy Technology Data Exchange (ETDEWEB)

    Simsek, E.H.; Bilgesu, A.; Olcay, A. [Ankara University, Ankara (Turkey). Dept. of Chemical Engineering

    1995-06-01

    Preswelling of Mugla-Yatagan lignite with THF (tetrahydrofuran) followed by removal of the swelling agents results in higher extract yields, probably because the solvent molecules had easier access to the expanded pore structure of the swollen lignite. On the other hand, the yields of supercritical THF extract of the same lignite sample indicated that during removal of the swelling agent the expanded pore structure had collapsed. The results show that higher extract yields might have been obtained by the combined effect of the expanded pore structure of the swollen lignite and the solvent power of the mixed solvent, i.e. of the mixture of swelling agent and supercritical extraction fluid. 14 refs., 4 tabs.

  13. Validação de métodos para determinação de fluoxetina em cápsulas Validation of methods for determination of fluoxetine capsules

    Directory of Open Access Journals (Sweden)

    Marlene Maria Fregonezi-Nery

    2008-01-01

    Full Text Available A UV spectrophotometric method was developed and validated and a chromatographic method was adapted from the American Pharmacopeia for the analysis of Fluoxetine Hydrochloride capsules. Ethanol was used as solvent for the spectrophotometric method, with detection and determination at 276 nm. The separation for the chromatographic method was carried out using the reversed-phase column LC-8, triethylamine buffer, stabilizer free tetrahydrofuran and methanol (5:3.5:1.5, pH 6.0 as mobile phase and detection at 227 nm. The results obtained for both methods showed to be accurate, precise, robust and linear over the concentration range 100.00 - 300.00 µg/mL and 40.00 - 80.00 µg/mL of fluoxetine hydrochloride for the spectrophotometric and chromatographic methods, respectively. The accuracy of the methods was evaluated by a recovery test and showed results between 98.89 and 101.10%.

  14. Evaluation of dosimetric characteristics of graphene oxide/PVC nanocomposite for gamma radiation applications

    Energy Technology Data Exchange (ETDEWEB)

    Feizi, Shahzad; Malekie, Shahryar; Ziaie, Farhood [Nuclear Science and Technology Research Institute (NSTRI), Karaj (Iran, Islamic Republic of). Radiation Application Research School; Rahighi, Reza; Tayyebi, Ahmad [Univ. of Technology, Tehran (Iran, Islamic Republic of). Dept. of Physics

    2017-04-01

    Graphene oxide-polyvinyl chloride composite was prepared using tetrahydrofuran solvent-assisted dispersion of characterized nano flakes of graphene oxide in polymer matrix. Electrical percolation threshold of GO/PVC nanocomposite was determined via a finite element simulation method with a 2D model and compared with experimental results. A conductive cell with two silver coated walls was designed and fabricated for exploring dosimetric properties of the composite. Some characteristics of the new nanocomposite such as linearity of dose response, repeatability, sensitivity and angular dependence are investigated. According to 2D proposed method, obtained data associated to electrical conductivity of the GO/polymer composite for PVC matrix plotted in different GO weight percentages and had good compatibility (validity) with experimental data. The dose response is linear in the 17-51 mGy dose range and it can be introduced for gamma radiation dosimetry in diagnostic activities.

  15. Investigation of Polyvinyl Chloride and Thermoplastic Polyurethane Waste Blend Miscibility

    Directory of Open Access Journals (Sweden)

    Agnė LAUKAITIENĖ

    2013-12-01

    Full Text Available In this study the miscibility of polyvinyl chloride (PVC and poly-e-caprolactone based thermoplastic polyurethanes (TPU waste blends were investigated by dilute solution viscometry. The miscibility criteria a, Db, DB, and D[h] were used to assess the degree of miscibility of polymers in tetrahydrofuran solution. Also, to assess the miscibility and microstructure of PVC/TPU blends obtained by solution casting have been characterized by X-ray diffraction. The tensile strength and deformability properties varying on the blend composition were determined. It was found that PVC and TPU are partially miscible, their blend is amorphous and show two-phase structure. TPU changes the mechanical behaviour of PVC the blends. Increase of TPU content causes PVC elongation at break increase and tensile strength decreases. DOI: http://dx.doi.org/10.5755/j01.ms.19.4.3145

  16. Carbon nanofiber supported bimetallic PdAu nanoparticles for formic acid electrooxidation

    Science.gov (United States)

    Qin, Yuan-Hang; Jiang, Yue; Niu, Dong-Fang; Zhang, Xin-Sheng; Zhou, Xing-Gui; Niu, Li; Yuan, Wei-Kang

    2012-10-01

    Carbon nanofiber (CNF) supported PdAu nanoparticles are synthesized with sodium citrate as the stabilizing agent and sodium borohydride as the reducing agent. High resolution transmission electron microscopy (HRTEM) characterization indicates that the synthesized PdAu particles are well dispersed on the CNF surface and X-ray diffraction (XRD) characterization indicates that the alloying degree of the synthesized PdAu nanoparticles can be improved by adding tetrahydrofuran to the synthesis solution. The results of electrochemical characterization indicate that the addition of Au can promote the electrocatalytic activity of Pd/C catalyst for formic acid oxidation and the CNF supported high-alloying PdAu catalyst possesses better electrocatalytic activity and stability for formic acid oxidation than either the CNF supported low-alloying PdAu catalyst or the CNF supported Pd catalyst.

  17. Molecular layer deposition of polyurethane-Polymerisation at the very contact to native aluminium and copper

    Science.gov (United States)

    Fug, Frank; Petry, Adrien; Jost, Hendrik; Ahmed, Aisha; Zamanzade, Mohammad; Possart, Wulff

    2017-12-01

    Thin layers of polyurethane monomers (diol, triol, diisocyanate) are deposited from gas phase onto native aluminium and copper surfaces. According to infrared external reflection absorption spectra both alcohols undergo only weak physical interactions with both metals. The diisocyanate on the other hand reveals resistance against desorption and rich new spectral features indicate strong adhesion. Preparation of urethane layers by sequential deposition of diisocyanate and diol yields urethane linkages. Urethane is formed faster on Cu than on Al. Scanning force microscopy reveals heterogeneous layers with metal dependent morphology. They show poor resistance against tetrahydrofuran rinsing i.e. most part of the formed urethane containing molecules are removed. Nevertheless, a residue of molecules sticks on the metal. It contains strongly adsorbed isocyanates and few isocyanate units which are bonded to diol units via urethane links. Further improvement of the molecular layer deposition is necessary to achieve well-crosslinked polyurethane layers.

  18. Development and validation of a dissolution method for warfarin sodium and aspirin combination tablets.

    Science.gov (United States)

    McCormick, T J; Gibson, A B; Diana, F J

    1997-08-01

    A dissolution method for warfarin sodium-aspirin combination tablets was developed which utilizes USP Apparatus 1 (baskets) at 50 rpm with 900 ml of phosphate buffer (pH 6.8; 0.05 M) medium at 37 degrees C. A reversed-phase liquid chromatographic method was also developed for the simultaneous determination of warfarin sodium, aspirin and salicylic acid on an octadecylsilica column using acetonitrile-tetrahydrofuran-glacial acetic acid-water (23:5:5:67, v/v/v/v) as the mobile phase with UV detection at 282 nm. Validation data were obtained which demonstrate that the dissolution methodology is accurate, precise, linear and rugged for the combination tablets.

  19. Double concave cesium encapsulation by two charged sumanenyl bowls

    Energy Technology Data Exchange (ETDEWEB)

    Spisak, Sarah N.; Wei, Zheng; Petrukhina, Marina A. [Department of Chemistry, University at Albany, State University of New York, Albany, NY (United States); Rogachev, Andrey Yu. [Department of Chemistry, Illinois Institute of Technology, Chicago, IL (United States); Amaya, Toru [Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita (Japan); Hirao, Toshikazu [Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita (Japan); The Institute of Scientific and Industrial Research, Osaka University (Japan)

    2017-03-01

    The controlled reaction of Na and Cs, two alkali metals of different ionic sizes and binding abilities, with sumanene (C{sub 21}H{sub 12}) affords a novel type of organometallic sandwich [Cs(C{sub 21}H{sub 11}{sup -}){sub 2}]{sup -}, which crystallized as a solvent-separated ion pair with a [Na(18-crown-6)(THF){sub 2}]{sup +} cation (where THF=tetrahydrofuran). The unprecedented double concave encapsulation of a metal ion by two bowl-shaped sumanenyl anions in [Cs(C{sub 21}H{sub 11}{sup -}){sub 2}]{sup -} was revealed crystallographically. Evaluation of bonding and energetics of the remarkable product was accomplished computationally (B2PLYP-D/TZVP/ZORA), providing insights into its formation. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Simple home-made sensors for potentiometric titrations. [Nitroform CH(NO/sub 2/)/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Selig, W.

    1982-04-01

    A sensor for potentiometric titrations was prepared by coating a spectroscopic graphite rod with a solution of poly(vinyl chloride) and dioctyphthalate in tetrahydrofuran. The reference electrode was an Ag/AgCl single-junction electrode. The sensor was used in precipitation, acid-base, compleximetric, and redox titrations. Preparation of the coated-graphite sensor is simple and rapid. Moreover, it is quite inexpensive. A limitation is its applicability in aqueous media only, because organic solvents will dissolve the membrane. Various uncoated types of graphite have also been investigated as sensors, particularly in two applications of interest in the analysis of propellants: the titration of nitroform and perchlorate. Obviously, these sensors can be used also in nonaqueous, or partially nonaqueous media. These sensors may also find use in the potentiometric titration of fluoride vs La(III) or Th(IV).

  1. Effects of phthalic anhydride modification on horseradish peroxidase stability and activity.

    Science.gov (United States)

    O'Brien, Anne Marie; Smith, Andrew T; O'Fágáin, Ciarán

    2003-01-20

    Phthalic anhydride (PA) modification stabilizes horseradish peroxidase (HRP) by reversal of the positive charge on two of HRP's six lysine residues. Native and PA-HRP had half-inactivation temperatures of 51 and 65 degrees C and half-lives at 65 degrees C of 4 and 17 min, respectively. PA-HRP was more resistant to dimethylformamide at room temperature and tetrahydrofuran at 60 degrees C and to unfolding by heat, guanidine chloride, EDTA, and the reducing agent tris(2-carboxyethyl)phosphine hydrochloride. Binding of the hydrophobic probe Nile Red to the native enzyme and to PA-HRP was similar. The kinetics of both HRPs with the substrates ABTS, ferrocyanide, ferulic acid, and indole-3-propionic acid were measured, as was binding of the inhibitor benzhydroxamic acid. Small improvements in the catalytic properties were detected. Copyright 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 233-240, 2003.

  2. 2-(5-Iodo-2-oxoindolin-3-ylidenehydrazinecarbothioamide including an unknown solvate

    Directory of Open Access Journals (Sweden)

    Viviane Conceição Duarte de Bittencourt

    2014-06-01

    Full Text Available The molecule of the title compound, C9H7IN4OS, is almost planar (r.m.s. deviation = 0.0373 Å. In the molecule, N—H...N and N—H...O hydrogen bonds generate, respectively, S(5 and S(6 ring motifs. In the crystal, molecules are linked via N—H...O hydrogen bonds, forming chains propagating along [010]. These chains are linked via S...I contacts [3.4915 (16 Å], forming sheets lying parallel to (100. A region of disordered electron density, probably a disordered tetrahydrofuran solvent molecule, was treated using the SQUEEZE routine in PLATON [Spek (2009. Acta Cryst. D65, 148–155]. The formula mass and unit-cell characteristics were not taken into account during refinement.

  3. The intake of carotenoids in Denmark

    DEFF Research Database (Denmark)

    Leth, Torben; Jakobsen, Jette; Andersen, N. L.

    2000-01-01

    To estimate the intake of carotenoids in the Danish population Danish fruits and vegetables were screened with an HPLC method consisting of extraction with ethanol:tetrahydrofuran, separation by reversed phase HPLC with the mobile phase acetonitril:methanol:dichlormethan, triethylamin, BHT...... and detection at 450 nm. Food intakes were estimated by the national dietary surveys (1995) from 7 days' food registration (n = 1837 adults), which allows the whole diet to be described by the mean intake and intake distribution of 207 raw or semiprepared foods. By multiplication with the mean content...... in the foods the mean intake and intake distribution of the carotenoids were calculated. Carrots and tomatoes have both high contents of carotenoids (8,450 mu g/100 g alpha- + beta-carotene and 4,790 mu g/100 g lycopene, respectively) and high intakes (19 and 15 g/day, respectively) and were responsible for 47...

  4. Self-consistency of electron-THF cross sections using electron swarm techniques

    Science.gov (United States)

    Casey, M. J. E.; de Urquijo, J.; Serkovic Loli, L. N.; Cocks, D. G.; Boyle, G. J.; Jones, D. B.; Brunger, M. J.; White, R. D.

    2017-11-01

    The drift velocity and first Townsend ionization coefficient of electrons in gaseous tetrahydrofuran are measured over the range of reduced electric fields 4-1000 Td using a pulsed-Townsend technique. The measured drift velocities and Townsend ionization coefficients are subsequently used, in conjunction with a multi-term Boltzmann equation analysis, as a further discriminative assessment on the accuracy and completeness of a recently proposed set of electron-THF vapor cross sections. In addition, the sensitivity of the transport coefficients to uncertainties in the existing cross sections is presented. As a result of that analysis, a refinement of the momentum transfer cross section for electron-THF scattering is presented, along with modifications to the neutral dissociation and dissociative electron attachment cross sections. With these changes to the cross section database, we find relatively good self-consistency between the measured and simulated drift velocities and Townsend coefficients.

  5. Morphogenesis and Optoelectronic Properties of Supramolecular Assemblies of Chiral Perylene Diimides in a Binary Solvent System.

    Science.gov (United States)

    Shang, Xiaobo; Song, Inho; Ohtsu, Hiroyoshi; Tong, Jiaqi; Zhang, Haoke; Oh, Joon Hak

    2017-07-14

    Chiral supramolecular structures are attracting great attention due to their specific properties and high potential in chiral sensing and separation. Herein, supramolecular assembling behaviors of chiral perylene diimides have been systematically investigated in a mixed solution of tetrahydrofuran and water. They exhibit remarkably different morphologies and chiral aggregation behaviors depending on the mixing ratio of the solvents, i.e., the fraction of water. The morphogenesis and optoelectronic properties of chiral supramolecular structures have been thoroughly studied using a range of experimental and theoretical methods to investigate the morphological effects of chiral supramolecular assemblies on the electrical performances and photogenerated charge-carrier behaviors. In addition, chiral perylene diimides have been discriminated by combining vibrational circular dichroism with theoretical calculations, for the first time. The chiral supramolecular nanostructures developed herein strongly absorb visible spectral region and exhibit high photoresponsivity and detectivity, opening up new opportunities for practical applications in optoelectronics.

  6. Determination of diclofenac sodium and related compounds in raw materials and formulations.

    Science.gov (United States)

    Beaulieu, N; Lovering, E G; Lefrançois, J; Ong, H

    1990-01-01

    A liquid chromatographic method has been developed for determination of drug and related compounds in diclofenac sodium raw material, slow-release, and enteric coated tablets. The method specifies a 5 microns octadecylsilane bonded phase column, a mobile phase of tetrahydrofuran-acetonitrile-buffer, pH 5 (1 + 4 + 8.3), and detection at 229 nm. The method resolves 10 known related compounds with limits of quantitation of 0.2% or less. Seventeen drug raw material samples were evaluated. Total impurity levels ranged from 0.1 to 0.9%. The method has also been used for determination of drug content in raw materials and formulations. Mean assay levels in drug raw materials ranged between 98.3% and 101.8%.

  7. Metal-Free Polymethyl Methacrylate (PMMA Nanoparticles by Enamine “Click” Chemistry at Room Temperature

    Directory of Open Access Journals (Sweden)

    José A. Pomposo

    2011-10-01

    Full Text Available “Click” chemistry has become an efficient avenue to unimolecular polymeric nanoparticles through the self-crosslinking of individual polymer chains containing appropriate functional groups. Herein we report the synthesis of ultra-small (7 nm in size polymethyl methacrylate (PMMA nanoparticles (NPs by the “metal-free” cross-linking of PMMA-precursor chains prepared by reversible addition-fragmentation chain transfer (RAFT polymerization containing b-ketoester functional groups. Intramolecular collapse was performed by the one-pot reaction of b-ketoester moieties with alkyl diamines in tetrahydrofurane at r.t. (i.e., by enamine formation. The collapsing process was followed by size exclusion chromatography and by nuclear magnetic resonance spectroscopy. The size of the resulting PMMA-NPs was determined by dynamic light scattering. Enamine “click” chemistry increases the synthetic toolbox for the efficient synthesis of metal-free, ultra-small polymeric NPs.

  8. Activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate.

    Science.gov (United States)

    Domańska, Urszula; Marciniak, Andrzej

    2008-09-04

    The activity coefficients at infinite dilution, gamma 13 (infinity) for 32 solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, tetrahydrofurane, tert-butyl methyl ether, and water in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][CF3SO3] were determined by gas-liquid chromatography at the temperatures from 298.15 to 368.15 K. The partial molar excess enthalpies at infinite dilution values Delta H 1 (E,infinity) were calculated from the experimental gamma 13 (infinity) values obtained over the temperature range. The selectivities for the hexane/benzene, cyclohexane/benzene, n-hexane/thiophene, n-decane/thiophene, cyclohexane/thiophene, toluene/thiophene, and oct-1-ene/thiophene separation problems were calculated from the gamma 13 (infinity). Obtained values were compared to the literature values for the other ionic liquids, NMP, and sulfolane.

  9. Trienylfuranol A and trienylfuranone A-B: metabolites isolated from an endophytic fungus, Hypoxylon submoniticulosum, in the raspberry Rubus idaeus.

    Science.gov (United States)

    Burgess, Kevin M N; Ibrahim, Ashraf; Sørensen, Dan; Sumarah, Mark W

    2017-06-01

    A strain of Hypoxylon submonticulosum was isolated as an endophyte from a surface-sterilized leaf of a cultivated raspberry (Rubus idaeus). The liquid culture extract displayed growth inhibition activity against Saccharomyces cerevisiae using a disc diffusion assay. The extract's major component was identified as a new natural product, trienylfuranol A (1S,2S,4R)-1-((1'E,3'E)-hexa-1',3',5'-trienyl)-tetrahydro-4-methylfuran-2-ol (1), by high-resolution LC-MS and 1D and 2D NMR spectroscopy. Two additional new metabolites, trienylfuranones A (2) and B (3), were isolated as minor components of the extract and their structure elucidation revealed that they were biosynthetically related to 1. Absolute stereochemical configurations of compounds 1-3 were confirmed by NOE NMR experiments and by the preparation of Mosher esters. Complete hydrogenation of 1 yielded tetrahydrofuran 7 that was used for stereochemical characterization and assessment of antifungal activity.

  10. Synthesis of core-fluorescent four-armed star and dicyclic 8-shaped poly(THF)s by electrostatic self-assembly and covalent fixation (ESA–CF) protocol

    KAUST Repository

    Fujiwara, Susumu

    2013-12-07

    A pair of four-armed star and dicyclic 8-shaped poly(tetrahydrofuran)s, poly(THF)s, possessing a perylene diimide group at the core position (Ia and Ib, respectively) were synthesized by means of an electrostatic self-assembly and covalent fixation (ESA–CF) protocol. Mono- and bifunctional poly(THF)s having N-phenylpiperidinium salt end groups accompanying a perylene diimide tetracarboxylate as a counteranion were prepared by the ion-exchange reaction, and the subsequent covalent conversion by reflux in toluene afforded the corresponding core-fluorescent four-armed star and dicyclic 8-shaped poly(THF)s, (Ia and Ib, respectively) for the use of single-molecule fluorescence microscopy measurements.

  11. Biomass pre-treatment for co-production of high-concentration C5- and C6-carbohydrates and their derivatives

    Science.gov (United States)

    Dumesic, James A.; Martin Alonso, David; Luterbacher, Jeremy Scott

    2016-06-07

    Described is a method of processing biomass to separate it into a liquid fraction enriched in solubilized C5-sugar-containing oligomers and C-5 sugar monomers and a solid fraction enriched in substantially insoluble cellulose and C6-sugar-containing oligomers. The method includes the steps of reacting biomass with a solvent system comprising water, at least one lactone, or at least one furan, or at least one cyclic ether, and at least one acid, for a time and at a temperature to yield the liquid and solid fractions. The liquid and solid fractions may then be separated. Gamma-valeroloactone is a preferred lactone for use in the solvent system. Tetrahydrofuran is a preferred furan species for use in the solvent system.

  12. Development and Characterization of Novel Polyurethane Films Impregnated with Tolfenamic Acid for Therapeutic Applications

    Directory of Open Access Journals (Sweden)

    Hilal Istanbullu

    2013-01-01

    Full Text Available The present study deals with the preparation of polyurethane (PU films impregnated with a nonsteroidal anti-inflammatory drug, tolfenamic acid (TA. Solvent evaporation technique has been employed for the preparation of TA-PU films in two different ratios of 1 : 2 and 1 : 5 in Tetrahydrofuran (THF or THF-ethanol mixtures. The prepared films were characterized using X-Ray Diffraction (XRD, Differential Scanning Calorimetry (DSC, Fourier Transform Infrared Spectroscopy (FTIR, Scanning Electron Microscopy (SEM, and release studies. The results indicate transformation of crystalline TA to its amorphous form. The degree of crystallinity changes both by increasing the polymer concentration and solvent used for the film preparations. The release profiles of TA were also found to be affected, showing a decrease from approximately 50% to 25% from 1 : 2 to 1 : 5 ratios, respectively.

  13. Effect of solvents on the optical and morphological properties of MEH-PPV: PC70BM nanocomposites

    Science.gov (United States)

    Mhamdi, Asya; Ltaief, Adnen; Bouazizi, Abdelaziz

    2017-10-01

    Focused on phase separation and morphologies of polymer poly [2-methoxy-5-(2'-ethyl) hexoxy-1,4-phenylenevinylene] (MEH-PPV) and [6,6]-phenylC71-butyric acid methyl ester (PC70BM) nanocomposite, we studied the effect of organic solvent on the optical and morphological properties of these blends. The MEH-PPV: PC70BM films was prepared using three different solvent; Tetrahydrofuran (THF), Chlorobenzene (CB) and Toluene. On the other hand, the effect of 1-8 octanedithiol additives is also studied with the same different solvents. These blend films are characterized by photoluminescence spectroscopy, UV-Vis absorption spectroscopy and atomic force microscopy (AFM). The photoluminescence results show that the THF solvent provide the better charge transfer. In a morphological view point, the phase segregation was clearly appearing by the addition of the additive on the surface of the blend films.

  14. Electrospun Nanocomposite Materials, A Novel Synergy of Polyurethane and Bovine Derived Hydroxyapatite

    Science.gov (United States)

    Bozkurt, Y.; Sahin, A.; Sunulu, A.; Aydogdu, M. O.; Altun, E.; Oktar, F. N.; Ekren, N.; Gunduz, O.

    2017-04-01

    Polyurethane (PU) is a synthetic polymer that is used for construction of scaffold in tissue engineering applications in order to obtain desirable mechanical, physical and chemical properties like elasticity and durability. Bovine derived hydroxyapatite (BHAp) is a ceramic based natural polymer that is used as the most preferred implant material in orthopedics and dentistry due to their chemically and biologically similarity to the mineral phase found in the human bone structure. PU and bovine derived hydroxyapatite (BHAp) solutions with different concentrations were prepared with dissolving polyurethane and BHAp in Dimethylformamide (DMF) and Tetrahydrofuran (THF) solutions. Blended PU-BHAp solutions in different concentrations were used for electrospinning technique to create nanofiber scaffolds and new biocomposite material together. SEM, FTIR and physical analysis such as viscosity, electrical conductivity, density measurement and tensile strength measurement tests were carried out after production process.

  15. Polypeptide Liquid Crystal Assisted Assembly of Cylindrically Symmetric Silica-Polypeptide Hybrid Microparticles

    Science.gov (United States)

    Russo, Paul; Rosu, Cornelia; Jacobeen, Shane; Park, Katherine; Yunker, Peter; Reichmanis, Elsa

    Liquid crystals can organize dispersed particles into exotic structures. Matching the particle surface coating to the chemistry of the mesogenic phase permits a tight focus on factors such as extended particle shape. The colloidal particles developed for this work consist of a magnetic and fluorescent cylinder-like silica core. One end of the silica is rounded, almost hemispherical, giving the particles a bullet-like shape. These particles are functionalized with helical poly(γ-stearyl-L-glutamate) and dispersed, at different concentrations in cholesteric liquid crystals (ChLC) of the same polymer in tetrahydrofuran. Defects introduced by the particles to the director field of the bulk PSLG/THF host led to a variety of phases, including a quasi-hexagonal alignment of the particles. National Science Foundation.

  16. Microfluidic synthesis of atto-liter scale double emulsions toward ultrafine hollow silica spheres with hierarchical pore networks.

    Science.gov (United States)

    Jeong, Woong-Chan; Choi, Minkee; Lim, Che Ho; Yang, Seung-Man

    2012-12-21

    A facile PDMS-glass hybrid microfluidic device is developed for generating uniform submicrometer-scale double emulsion droplets with unprecedented simplicity and controllability. Compared with planar flow-focusing geometries, our three-dimensional flow-focusing geometry is advantageous for stably producing femto- to atto-liter droplets without the retraction problem of the dispersed phase fluid. In addition, this microfluidic platform can withstand the use of strong organic solvents (e.g. tetrahydrofuran (THF) and toluene) as a dispersed phase without deforming PDMS devices because the dispersed phase containing organic solvents does not directly contact the PDMS wall. In particular, monodisperse double emulsions are generated spontaneously via the internal phase separation of single emulsions driven by the diffusion of a co-solvent (tetrahydrofuran) in microfluidic devices. Finally, we demonstrated that the double emulsions can be used as morphological templates of ultrafine spherical silica capsules with controlled hierarchical pore networks via the evaporation-induced self-assembly (EISA) method. During EISA, triblock copolymers (Pluronic F127) act as a surfactant barrier separating the internal droplet from the continuous oil phase, resulting in the 'inverse' morphology (i.e. hydrophobic polymer-in-water-in-oil emulsions). Depending on the precursor composition and kinetic condition, various structural and morphological features, such as mesoporous hollow silica spheres with a single central core, multi-cores, or a combination of these with robust controllability can be seen. Electron microscopy (SEM, STEM, HR-TEM), small angle X-ray scattering (SAXS), and N(2) adsorption-desorption confirm the well-controlled hierarchical pore structure of the resulting particles.

  17. The effect of fullerenes and functionalized fullerenes on Daphnia magna phototaxis and swimming behavior.

    Science.gov (United States)

    Brausch, Kathryn A; Anderson, Todd A; Smith, Philip N; Maul, Jonathan D

    2011-04-01

    The effects of carbon fullerenes (C(60) ) on the environment is a growing concern as the use of nanotechnology continues to increase. Previous studies have reported alteration in Daphnia magna behavior, including increased hopping frequency, heart rate, and appendage movement in response to tetrahydrofuran-solubilized C(60) and increased hopping rate and appendage movement in response to tetrahydrofuran-solubilized C(60) HxC(70) Hx exposure. The objective of the current study was to evaluate effects of water-stirred C(60) and sonicated carboxylic acid functionalized fullerenes (fC(60) ) on D. magna behavior. Behavioral endpoints are important because changes in behavior can influence predator avoidance behaviors, alter predation risk, and potentially lead to population-level effects in D. magna. To evaluate the potential effect of fullerenes on phototactic behavior, D. magna were exposed to 545.4 µg/L C(60) and 545.6 µg/L fC(60) , and vertical position was monitored. Daphnia magna were also exposed to 545.4 µg/L C(60) , 545.6 µg/L fC(60) , and 829.3 µg/L fC(60) , and swimming movements were recorded. Fullerenes altered the vertical migration response of D. magna to the addition of food, but D. magna vertical position response to predator cues was similar for fullerenes and controls. In addition, D. magna reduced swimming speed when exposed to C(60) , but other components of D. magna swimming behavior were not affected. This research supports previous findings and suggests that C(60) may influence D. magna behavior and highlights the need for further research on sublethal behavioral modifications in aquatic organisms in response to nanomaterials. Copyright © 2011 SETAC.

  18. Freeze-substitution methods for Ni localization and quantitative analysis in Berkheya coddii leaves by means of PIXE

    Energy Technology Data Exchange (ETDEWEB)

    Budka, D. [Materials Research Group, iThemba LABS, P.O. Box 722, Somerset West 7129 (South Africa); Mesjasz-PrzybyIowicz, J. [Materials Research Group, iThemba LABS, P.O. Box 722, Somerset West 7129 (South Africa)]. E-mail: mesjasz@tlabs.ac.za; Tylko, G. [Materials Research Group, iThemba LABS, P.O. Box 722, Somerset West 7129 (South Africa); PrzybyIowicz, W.J. [Materials Research Group, iThemba LABS, P.O. Box 722, Somerset West 7129 (South Africa)

    2005-04-01

    Leaves of Ni hyperaccumulator Berkheya coddii were chosen as a model to investigate the influence of eight freeze-substitution protocols on the Ni content and distribution. Freeze-substitution of leaf samples cryofixed by high-pressure freezing was carried out in dry acetone, methanol, diethyl ether and tetrahydrofuran. The same substitution media were also used with dimethylglyoxime added as a precipitation reagent. The samples were infiltrated and embedded in Spurr's resin. Micro-PIXE analysis of Ni concentration and localization, complemented by proton backscattering for matrix assessment, was performed using the nuclear microprobe at Materials Research Group, iThemba LABS, South Africa. True elemental maps and concentrations were obtained using GeoPIXE-II software. The results were compared with the control results obtained for the parallel air-dried samples, corrected for the water content. The highest Ni content was found in the leaf samples substituted in diethyl ether. This concentration was statistically different from the results obtained for other media. In case of diethyl ether medium Ni was mainly localized in the mesophyll tissue, and the distribution map of this element was in accordance with previous results obtained for freeze-dried and frozen-hydrated leaves of this species. The same distribution pattern was observed for specimens embedded in dry acetone, but Ni concentration was significantly lower. Tetrahydrofuran medium preserved Ni preferentially in the epidermis and vascular tissue, and the elemental map for samples embedded in this medium was distorted. Ni was almost completely washed out from samples substituted in methanol and it was thus impossible to obtain a picture of its distribution. Dimethylglyoxime did not improve the preservation of this element. These results show that diethyl ether is a suitable substitution medium for assessment of Ni concentration and distribution in leaves of B. coddii.

  19. Thermodynamic and kinetic study of chiral separations of coumarin-based anticoagulants on derivatized amylose stationary phase.

    Science.gov (United States)

    Gebreyohannes, Kahsay G; McGuffin, Victoria L

    2010-09-17

    Thermodynamic and kinetic studies are performed on amylose derivatized with tris-(3,5-dimethylphenyl carbamate) stationary phase for the chiral separation of coumarin-based anticoagulants. Polar-organic eluents that contain acetonitrile as bulk solvent with modifiers such as methanol, i-butanol, t-butanol, and tetrahydrofuran are used in the study. Temperature is varied from 5 to 45 degrees C at constant pressure of 1500psi. In general, both retention and enantioselectivity decrease as the temperature increases and as hydrogen bond donating ability of the modifiers increases. The van't Hoff plots are found to show both linear and non-linear behavior. The non-linear plots are believed to be the result of conformational changes in the derivatized amylose phase and are observed around room temperature. The retention behavior in acetonitrile mobile phase provides a linear enthalpy-entropy compensation plot, indicating that all coumarins may have a similar retention mechanism. In contrast, enthalpy-entropy compensation is not observed for warfarin and coumatetralyl enantiomers when separated with different organic modifiers in the mobile phase. The kinetic data indicate that the rate of sorption is always greater than the rate of desorption. An increase in the concentration of alcohol modifiers causes an increase in the desorption rate constant. In contrast, an increase in the concentration of tetrahydrofuran causes a decrease in the desorption rate constant. This effect is most significant for the second eluted enantiomer of coumatetralyl, for which the desorption rate is 36 times slower than the first eluted enantiomer. 2010 Elsevier B.V. All rights reserved.

  20. Total synthesis of macrodiolide ionophores aplasmomycin A and boromycin via double ring contraction.

    Science.gov (United States)

    Avery, Mitchell A; Choudhry, Satish C; Dhingra, Om Prakash; Gray, Brian D; Kang, Myung-chol; Kuo, Shen-chun; Vedananda, Thalathani R; White, James D; Whittle, Alan J

    2014-12-07

    The half structure of the symmetrical macrodiolide aplasmomycin A was synthesized by alkylation of a C3-C10 α-sulfonyl ketone subunit, prepared from (R)-pulegone and protected as a C3 ortholactone with (2R,3R)-butanediol, by a protected 15,16-dihydroxy (12E)-allylic chloride representing C11-C17. The latter was obtained from (2S,3R)-1,2-epoxy-3-butanol and propargyl alcohol. Regio- and stereoselective 5-exo-trig cyclization of the ene diol moiety in this segment, mediated by N-bromosuccinimide, led to the (2R,3S,5R)-tetrahydrofuran substructure of aplasmomycin A. Attachment of an α-acetic ester at the C3 carboxylic acid and esterification of the 3'-hydroxyl group of the tetrahydrofuran as its α-bromoacetate enabled coupling of two aplasmomycin half structures as an α-acyloxy acetate. Mukaiyama macrolactonization of this hydroxy acid afforded a symmetrical 36-membered diolide. Base-mediated double Chan rearrangement of this bis α-acyloxy dilactone caused ring contraction to the 34-membered macrocycle of desboroaplasmomycin A while generating the transannular 2-hydroxy-3-hemiketal motif of the natural product in the correct configuration. Final incorporation of boron into the tetraol core produced aplasmomycin A, isolated as its sodium borate. Extension of this route to the unsymmetrical macrodiolide boromycin was accomplished by modifications that included reversal of C12-C13 olefin geometry to (Z) for the southern half structure along with stereoselective hydride reductions of the C9 ketone that produced (9R) and (9S) alcohols for northern and southern half structures, respectively. Coupling of these half structures was made using an α-acyloxy ester linkage as for aplasmomycin A, but ring closure in this case was orchestrated via a blocked C16 alcohol that left open the C15 hydroxyl group of the southern half for Mukaiyama macrolactonization. A double Chan rearrangement of the resulting 35-membered macrocycle produced the 33-membered diolide of

  1. Oxidative stress-mediated hemolytic activity of solvent exchange-prepared fullerene (C{sub 60}) nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Trpkovic, Andreja; Todorovic-Markovic, Biljana; Kleut, Duska; Jovanovic, Svetlana; Dramicanin, Miroslav; Markovic, Zoran [Vinca Institute of Nuclear Sciences, POB 522, University of Belgrade, Belgrade 11000 (Serbia); Misirkic, Maja; Janjetovic, Kristina; Vucicevic, Ljubica [Institute for Biological Research ' Sinisa Stankovic' , University of Belgrade (Serbia); Pantovic, Aleksandar; Trajkovic, Vladimir, E-mail: zormark@vinca.rs, E-mail: vtrajkovic@eunet.rs [Institute of Microbiology and Immunology, School of Medicine, University of Belgrade, Dr Subotica 1, Belgrade 11000 (Serbia)

    2010-09-17

    The present study investigated the hemolytic properties of fullerene (C{sub 60}) nanoparticles prepared by solvent exchange using tetrahydrofuran (nC{sub 60}THF), or by mechanochemically assisted complexation with macrocyclic oligosaccharide gamma-cyclodextrin (nC{sub 60}CDX) or the copolymer ethylene vinyl acetate-ethylene vinyl versatate (nC{sub 60}EVA-EVV). The spectrophotometrical analysis of hemoglobin release revealed that only nC{sub 60}THF, but not nC{sub 60}CDX or nC{sub 60}EVA-EVV, was able to cause lysis of human erythrocytes in a dose- and time-dependent manner. Atomic force microscopy revealed that nC{sub 60}THF-mediated hemolysis was preceded by erythrocyte shrinkage and increase in cell surface roughness. A flow cytometric analysis confirmed a decrease in erythrocyte size and demonstrated a significant increase in reactive oxygen species production in red blood cells exposed to nC{sub 60}THF. The nC{sub 60}THF-triggered hemolytic activity was efficiently reduced by the antioxidants N-acetylcysteine and butylated hydroxyanisole, as well as by serum albumin, the most abundant protein in human blood plasma. These data indicate that nC{sub 60}THF can cause serum albumin-preventable hemolysis through oxidative stress-mediated damage of the erythrocyte membrane.

  2. A first archetype of boron dipyrromethene-phthalocyanine pentad dye: design, synthesis, and photophysical and photochemical properties.

    Science.gov (United States)

    Göl, Cem; Malkoç, Mustafa; Yeşilot, Serkan; Durmuş, Mahmut

    2014-05-28

    A novel type of phthalocyanine pentad containing four boron dipyrromethene (BODIPY) units at peripheral positions of the phthalocyanine framework has been designed and synthesized for the first time. The Sonogashira coupling reaction between 4,4'-difluoro-8-(4-ethynyl)-phenyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene (Ethynyl-BODIPY) and 2(3),9(10),16(17),23(24)-tetrakis(iodo) zinc(ii) phthalocyanine (Iodo-Pc) has been used for the synthesis of the target compound. The BODIPY-phthalocyanine pentad dye (BODIPY-Pc) has been fully characterized by (1)H NMR, MALDI-TOF mass, FT-IR and UV-Vis spectroscopic techniques and elemental analysis as well. The photoinduced energy transfer process for this dye system was explored in tetrahydrofuran solution. The singlet oxygen generation capability and photodegradation behaviours of this BODIPY-Pc pentad dye were also investigated in DMSO for the determination of the usability of this new type of dye system as a photosensitizer in PDT applications.

  3. Effect of the high cross flow velocity on performance of a pilot-scale anaerobic membrane bioreactor for treating antibiotic solvent wastewater.

    Science.gov (United States)

    Hu, Dongxue; Xiao, Tingting; Chen, Zhaobo; Wang, Haixu; Xu, Jiao; Li, Xue; Su, Haiyan; Zhang, Ying

    2017-11-01

    The effect of high cross flow velocity (CFV) on the operational efficiency of a pilot-scale anaerobic membrane bioreactor (AnMBR) treating antibiotic solvent effluents was explored. The average of total Chemical Oxygen Demand (COD) and tetrahydrofuran (THF) removal efficiencies during four Runs were 96.5% and 98.7%. Meanwhile, biological removal contributions were 74.3% and 78%, the rest part was attributed by the physical removal process of the membrane block, VFA (Volatile Fatty Acids) and alpha value (VFA/alkalinity) increased with the increase of CFV, resulted alkalinity decreased. Biomass concentration mixed liquid suspended solids (MLSS) and mixed liquor volatile suspended solids (MLVSS) as well as the polysaccharide increased smoothly in the suspended sludge with the CFV increasing, and the protein content decreased gradually. However, the concentration of biomass, polysaccharide and protein presented opposite trends in the attached sludge of the membrane. The results indicated that AnMBR can effectively treat the antibiotic solvent wastewater under high CFV. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Micro-Tomographic Investigation of Ice and Clathrate Formation and Decomposition under Thermodynamic Monitoring

    Directory of Open Access Journals (Sweden)

    Stefan Arzbacher

    2016-08-01

    Full Text Available Clathrate hydrates are inclusion compounds in which guest molecules are trapped in a host lattice formed by water molecules. They are considered an interesting option for future energy supply and storage technologies. In the current paper, time lapse 3D micro computed tomographic (µCT imaging with ice and tetrahydrofuran (THF clathrate hydrate particles is carried out in conjunction with an accurate temperature control and pressure monitoring. µCT imaging reveals similar behavior of the ice and the THF clathrate hydrate at low temperatures while at higher temperatures (3 K below the melting point, significant differences can be observed. Strong indications for micropores are found in the ice as well as the THF clathrate hydrate. They are stable in the ice while unstable in the clathrate hydrate at temperatures slightly below the melting point. Significant transformations in surface and bulk structure can be observed within the full temperature range investigated in both the ice and the THF clathrate hydrate. Additionally, our results point towards an uptake of molecular nitrogen in the THF clathrate hydrate at ambient pressures and temperatures from 230 K to 271 K.

  5. Synthesis and Properties of Carbon Nanotube-Grafted Silica Nanoarchitecture-Reinforced Poly(Lactic Acid

    Directory of Open Access Journals (Sweden)

    Yao-Wen Hsu

    2017-07-01

    Full Text Available A novel nanoarchitecture-reinforced poly(lactic acid (PLA nanocomposite was prepared using multi-walled carbon nanotube (MWCNT-grafted silica nanohybrids as reinforcements. MWCNT-grafted silica nanohybrids were synthesized by the generation of silica nanoparticles on the MWCNT surface through the sol-gel technique. This synthetic method involves organo-modified MWCNTs that are dispersed in tetrahydrofuran, which incorporates tetraethoxysilane that undergoes an ultrasonic sol-gel process. Gelation yielded highly dispersed silica on the organo-modified MWCNTs. The structure and properties of the nanohybrids were established using 29Si nuclear magnetic resonance, Raman spectroscopy, wide-angle X-ray diffraction, thermogravimetric analysis, and transmission electron microscopy. The resulting MWCNT nanoarchitectures were covalently assembled into silica nanoparticles, which exhibited specific and controllable morphologies and were used to reinforce biodegradable PLA. The tensile strength and the heat deflection temperature (HDT of the PLA/MWCNT-grafted silica nanocomposites increased when the MWCNT-grafted silica was applied to the PLA matrix; by contrast, the surface resistivity of the PLA/MWCNT-grafted silica nanocomposites appeared to decline as the amount of MWCNT-grafted silica in the PLA matrix increased. Overall, the reinforcement of PLA using MWCNT-grafted silica nanoarchitectures was efficient and improved its mechanical properties, heat resistance, and electrical resistivity.

  6. [6-chloro-3-pyridylmethyl-{sup 3}H]neonicotinoids as high-affinity radioligands for the nicotinic acetylcholine receptor: preparation using NaB{sup 3}H{sub 4} and LiB{sup 3}H{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Latli, Bachir; Casida, J.E. [California Univ., Berkeley, CA (United States). Dept. of Environmental Science Policy and Management; Chit Than; Morimoto, Hiromi; Williams, P.G. [Lawrence Berkeley National Lab., CA (United States)

    1996-11-01

    NaB{sup 3}H{sub 4} and LiB{sup 3}H{sub 4} at 78% and 97% isotopic enrichments, respectively, were used in the synthesis of {sup 3}H-labeled 1-(6-chloro-3-pyridyl)-methyl-2-nitromethyleneimidazolidine (CH-IMI) and N`-[(6-chloro-3-pyridyl)methyl]-n``-cyano-n`-methylacetamidine (acetamiprid) (two very potent insecticides) and of 1-(6-chloro-3-pyridyl)methyl-2-iminoimidazolidine (desnitro-IMI) (a metabolite of the commercial insecticides imidacloprid). 6-Chloronicotinoyl chloride was treated with either NaB{sup 3}H{sub 4} in methanol or LiB{sup 3}H{sub 4} in tetrahydrofuran and the resulting alcohol transformed to 2-chloro-5-chloromethylpyridine, which was then coupled to N-cyano-N`-methylacetamidine to give [{sup 3}H] acetamiprid (45 Ci/mmol). 2-Chloro-5-chloro[{sup 3}H]methylpyridine was also reacted with ethylenediamine and the product was either refluxed in absolute ethanol with 1,1-bis(methylthio)-2-nitro-ethylene to provide [{sup 3}H]CH-IMI or reacted in toluene with a solution of cyanogen bromide to produce [{sup 3}H] desnitro-IMI (each 55 Ci/mmol). (author).

  7. Engineering the Re-Entrant Hierarchy and Surface Energy of PDMS-PVDF Membrane for Membrane Distillation Using a Facile and Benign Microsphere Coating.

    Science.gov (United States)

    Lee, Eui-Jong; Deka, Bhaskar Jyoti; Guo, Jiaxin; Woo, Yun Chul; Shon, Ho Kyong; An, Alicia Kyoungjin

    2017-09-05

    To consolidate the position of membrane distillation (MD) as an emerging membrane technology that meets global water challenges, it is crucial to develop membranes with ideal material properties. This study reports a facile approach for a polyvinylidene fluoride (PVDF) membrane surface modification that is achieved through the coating of the surface with poly(dimethylsiloxane) (PDMS) polymeric microspheres to lower the membrane surface energy. The hierarchical surface of the microspheres was built without any assistance of a nano/microcomposite by combining the rapid evaporation of tetrahydrofuran (THF) and the phase separation from condensed water vapor. The fabricated membrane exhibited superhydrophobicity-a high contact angle of 156.9° and a low contact-angle hysteresis of 11.3°-and a high wetting resistance to seawater containing sodium dodecyl sulfate (SDS). Compared with the control PVDF-hexafluoropropylene (HFP) single-layer nanofiber membrane, the proposed fabricated membrane with the polymeric microsphere layer showed a smaller pore size and higher liquid entry pressure (LEP). When it was tested for the direct-contact MD (DCMD) in terms of the desalination of seawater (3.5% of NaCl) containing SDS of a progressively increased concentration, the fabricated membrane showed stable desalination and partial wetting for the 0.1 and 0.2 mM SDS, respectively.

  8. Evaluation of PHB/Clay nanocomposite by spin-lattice relaxation time

    Directory of Open Access Journals (Sweden)

    Mariana Bruno

    2008-12-01

    Full Text Available Poly(3-hydroxybutyrate (PHB based on nanocomposites containing different amounts of a commercial organically modified clay (viscogel B7 were prepared employing solution intercalation method. Three solvents, such as: CHCl3, dimethylchloride (DMC and tetrahydrofuran (THF were used. The relationship among the processing conditions; molecular structure and intermolecular interaction, between both nanocomposite components, were investigated using a nuclear magnetic resonance (NMR, as a part of characterization methodology, which has been used by Tavares et al. It involves the hydrogen spin-lattice relaxation time, T1H, by solid state nuclear magnetic resonance, employing low field NMR. X ray diffraction was also employed because it is a conventional technique, generally used to obtain the first information on nanocomposite formation. Changes in PHB crystallinity were observed after the organophilic nanoclay had been incorporated in the polymer matrix. These changes, in the microstructure, were detected by the variation of hydrogen nuclear relaxation time values and by X ray, which showed an increase in the clay interlamelar space due to the intercalation of the polymer in the clay between lamellae. It was also observed, for both techniques, that the solvents affect directly the organization of the crystalline region, promoting a better intercalation, considering that they behave like a plasticizer.

  9. TLC determination of flavonoids from different cultivars of Allium cepa and Allium ascalonicum

    Directory of Open Access Journals (Sweden)

    Pobłocka-Olech Loretta

    2016-12-01

    Full Text Available This study comprises the optimization and validation of a new TLC method for determination of flavonols in the bulbs of seven cultivars of onions and shallots. Separation was performed on RP-18 plates with the solvent mixture tetrahydrofuran/water/formic acid (40+60+6, V/V/V as a mobile phase. The method was evaluated for precision, linearity, LOD, LOQ, accuracy and robustness. Chromatographic analysis of the extracts revealed the presence of three main flavonols, quercetin, quercetin-4′-O-glucoside and quercetin-3,4′-O-diglucoside in the majority of analyzed cultivars. The content of flavonols in the analyzed extracts of onion bulbs varied from 123 (‘Exihibition’ to 1079 mg kg-1 fresh mass (fm (‘Hybing’ in edible parts, and from 1727 (‘Hyline’ to 28949 mg kg-1 fm (‘Red Baron’ in outer scales. The bulbs of two shallot cultivars contained 209 (‘Ambition’ and 523 mg kg-1 fm (‘Matador’ of flavonols in edible parts and 5426 and 8916 mg kg-1 fm in outer scales, respectively.

  10. Preparation and characterization, stable bismaleimide-triarylamine polymers with reversible electrochromic properties

    Science.gov (United States)

    Zhang, Haiyang; Niu, Haijun; Ji, Yan; Wu, Wenjun; Cai, Jiwei; Wang, Cheng; Lian, Yongfu; Bai, Xuduo; Wang, Wen

    2013-07-01

    A series of novel polyimides were synthesized from bismaleimide containing different diaminetriarylamines by Michael addition reaction. The prepolymer is readily soluble in many common organic solvents, such as CHCl3, Tetrahydrofuran (THF) and N, N-dimethyl formamide (DMF). Prepolymers can be solution-cast into transparent, tough, and flexible films. These aromatic polyimides display good thermal stabilities, i.e. 5% weight-loss temperatures in excess of 200 °C under nitrogen. All obtained polyimides revealed excellent stability of electrochromic characteristics, changing color from original yellowish to green. The energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of the investigated the polymers were estimated by experimental method are in the range of -4.78 eV to -4.98 eV and -1.64 eV to -2.09 eV vs the vacuum level, respectively. All the polymer films reveal good electrochemical and electrochromic stability under repeatedly switching electrode voltages, with coloration change from the yellow neutral state to green oxidized state.

  11. Bis[bis(pentamethylcyclopentadienylcobalt(III] tetrachloridocobaltate(II dichloromethane disolvate

    Directory of Open Access Journals (Sweden)

    Joseph S. Merola

    2013-09-01

    Full Text Available The title compound, [Co(C10H152]2[CoCl4]·2CH2Cl2, was isolated as a dichloromethane solvate and was formed in the reaction between lithium pentamethylcyclopentadienide and anyhydrous cobalt(II chloride in tetrahydrofuran. There are two decamethylcobaltocenium cations, one tetrachloridocobaltate(II anion and two dichloromethane solvent molecules in the formula unit. There is a slight disorder of the dichloromethane solvent which was treated with a two-site model [occupancy rates = 0.765 (4 and 0.235 (4]. The dichloromethane molecules display significant C—H...Cl interactions with the tetrachloridocobaltate(II dianion. The cobalt atom of the decamethylcobaltocenium cation sits on a twofold rotation axis, with only one pentamethylcyclopentadiene ligand being unique and the second generated by symmetry. The cobalt atom of the [CoCl4]−2 ion sits on a special site with -4 symmetry, with one unique chloride ligand and the others generated by the fourfold inversion axis.

  12. Direct synthesis of aqueous quantum dots through 4,4'-bipyridine-based twin ligand strategy.

    Science.gov (United States)

    Kalita, Mausam; Cingarapu, Sreeram; Roy, Santanu; Park, Seok Chan; Higgins, Daniel; Jankowiak, Ryszard; Chikan, Viktor; Klabunde, Kenneth J; Bossmann, Stefan H

    2012-04-16

    We report a new class of derivatized 4,4'-bipyridinium ligands for use in synthesizing highly fluorescent, extremely stable, water-soluble CdSe and CdTe quantum dots (QDs) for bioconjugation. We employed an evaporation-condensation technique, also known as solvated metal atom dispersion (SMAD), followed by a digestive ripening procedure. This method has been used to synthesize both metal nanoparticles and semiconductors in the gram scale with several stabilizing ligands in various solvents. The SMAD technique comprised evaporation condensation and stabilization of CdSe or CdTe in tetrahydrofuran. The as-prepared product was then digestively ripened in both water and dimethyl formamide, leading to narrowing of the particle size distributions. The ligands were synthesized by nucleophilic substitution (S(N)2) reactions using 4,4'-bipyridine as a nucleophile. Confocal microscopy images revealed the orange color of the nanocrystalline QDs with diameters of ~5 nm. The size has been confirmed by using transmission electron microscopy. As a part of our strategy, 85% of the 4,4'-bipyridinium salt was synthesized as propionic acid derivative and used to both stabilize the QDs in water and label basic amino acids and different biomarkers utilizing the carboxylic acid functional group. Fifteen percent of the 4,4'-bipyridinium salt was synthesized as N-propyl maleimide and used as a second ligand to label any protein containing the amino acid cysteine by means of a 1,4-Michael addition. © 2012 American Chemical Society

  13. Production of Fluconazole-Loaded Polymeric Micelles Using Membrane and Microfluidic Dispersion Devices.

    Science.gov (United States)

    Lu, Yu; Chowdhury, Danial; Vladisavljević, Goran T; Koutroumanis, Konstantinos; Georgiadou, Stella

    2016-05-25

    Polymeric micelles with a controlled size in the range between 41 and 80 nm were prepared by injecting the organic phase through a microengineered nickel membrane or a tapered-end glass capillary into an aqueous phase. The organic phase was composed of 1 mg·mL(-1) of PEG-b-PCL diblock copolymers with variable molecular weights, dissolved in tetrahydrofuran (THF) or acetone. The pore size of the membrane was 20 μm and the aqueous/organic phase volumetric flow rate ratio ranged from 1.5 to 10. Block copolymers were successfully synthesized with Mn ranging from ~9700 to 16,000 g·mol(-1) and polymeric micelles were successfully produced from both devices. Micelles produced from the membrane device were smaller than those produced from the microfluidic device, due to the much smaller pore size compared with the orifice size in a co-flow device. The micelles were found to be relatively stable in terms of their size with an initial decrease in size attributed to evaporation of residual solvent rather than their structural disintegration. Fluconazole was loaded into the cores of micelles by injecting the organic phase composed of 0.5-2.5 mg·mL(-1) fluconazole and 1.5 mg·mL(-1) copolymer. The size of the drug-loaded micelles was found to be significantly larger than the size of empty micelles.

  14. Production of Fluconazole-Loaded Polymeric Micelles Using Membrane and Microfluidic Dispersion Devices

    Directory of Open Access Journals (Sweden)

    Yu Lu

    2016-05-01

    Full Text Available Polymeric micelles with a controlled size in the range between 41 and 80 nm were prepared by injecting the organic phase through a microengineered nickel membrane or a tapered-end glass capillary into an aqueous phase. The organic phase was composed of 1 mg·mL−1 of PEG-b-PCL diblock copolymers with variable molecular weights, dissolved in tetrahydrofuran (THF or acetone. The pore size of the membrane was 20 μm and the aqueous/organic phase volumetric flow rate ratio ranged from 1.5 to 10. Block copolymers were successfully synthesized with Mn ranging from ~9700 to 16,000 g·mol−1 and polymeric micelles were successfully produced from both devices. Micelles produced from the membrane device were smaller than those produced from the microfluidic device, due to the much smaller pore size compared with the orifice size in a co-flow device. The micelles were found to be relatively stable in terms of their size with an initial decrease in size attributed to evaporation of residual solvent rather than their structural disintegration. Fluconazole was loaded into the cores of micelles by injecting the organic phase composed of 0.5–2.5 mg·mL−1 fluconazole and 1.5 mg·mL−1 copolymer. The size of the drug-loaded micelles was found to be significantly larger than the size of empty micelles.

  15. Bioactive Constituents of Zanthoxylum rhetsa Bark and Its Cytotoxic Potential against B16-F10 Melanoma Cancer and Normal Human Dermal Fibroblast (HDF) Cell Lines.

    Science.gov (United States)

    Santhanam, Ramesh Kumar; Ahmad, Syahida; Abas, Faridah; Safinar Ismail, Intan; Rukayadi, Yaya; Tayyab Akhtar, Muhammad; Shaari, Khozirah

    2016-05-24

    Zanthoxylum rhetsa is an aromatic tree, known vernacularly as "Indian Prickly Ash". It has been predominantly used by Indian tribes for the treatment of many infirmities like diabetes, inflammation, rheumatism, toothache and diarrhea. In this study, we identified major volatile constituents present in different solvent fractions of Z. rhetsa bark using GC-MS analysis and isolated two tetrahydrofuran lignans (yangambin and kobusin), a berberine alkaloid (columbamine) and a triterpenoid (lupeol) from the bioactive chloroform fraction. The solvent fractions and purified compounds were tested for their cytotoxic potential against human dermal fibroblasts (HDF) and mouse melanoma (B16-F10) cells, using the MTT assay. All the solvent fractions and purified compounds were found to be non-cytotoxic to HDF cells. However, the chloroform fraction and kobusin exhibited cytotoxic effect against B16-F10 melanoma cells. The presence of bioactive lignans and alkaloids were suggested to be responsible for the cytotoxic property of Z. rhetsa bark against B16-F10 cells.

  16. Bioactive Constituents of Zanthoxylum rhetsa Bark and Its Cytotoxic Potential against B16-F10 Melanoma Cancer and Normal Human Dermal Fibroblast (HDF Cell Lines

    Directory of Open Access Journals (Sweden)

    Ramesh Kumar Santhanam

    2016-05-01

    Full Text Available Zanthoxylum rhetsa is an aromatic tree, known vernacularly as “Indian Prickly Ash”. It has been predominantly used by Indian tribes for the treatment of many infirmities like diabetes, inflammation, rheumatism, toothache and diarrhea. In this study, we identified major volatile constituents present in different solvent fractions of Z. rhetsa bark using GC-MS analysis and isolated two tetrahydrofuran lignans (yangambin and kobusin, a berberine alkaloid (columbamine and a triterpenoid (lupeol from the bioactive chloroform fraction. The solvent fractions and purified compounds were tested for their cytotoxic potential against human dermal fibroblasts (HDF and mouse melanoma (B16-F10 cells, using the MTT assay. All the solvent fractions and purified compounds were found to be non-cytotoxic to HDF cells. However, the chloroform fraction and kobusin exhibited cytotoxic effect against B16-F10 melanoma cells. The presence of bioactive lignans and alkaloids were suggested to be responsible for the cytotoxic property of Z. rhetsa bark against B16-F10 cells.

  17. Synthesis, Characterization and Properties of Nanoparticles of Intermetallic Compounds

    Energy Technology Data Exchange (ETDEWEB)

    DiSalvo, Francis J. [Cornell Univ., Ithaca, NY (United States)

    2015-03-12

    The research program from 2010 to the end of the grant focused on understanding the factors important to the synthesis of single phase intermetallic nano-particles (NPs), their size, crystalline order, surface properties and electrochemical activity. The synthetic method developed is a co-reduction of mixtures of single metal precursors by strong, soluble reducing agents in a non-protic solvent, tetrahydrofuran (THF). With some exceptions, the particles obtained by room temperature reduction are random alloys that need to be annealed at modest temperatures (200 to 600 °C) in order to develop an ordered structure. To avoid significant particle size growth and agglomeration, the particles must be protected by surface coatings. We developed a novel method of coating the metal nanoparticles with KCl, a by-product of the reduction reaction if the proper reducing agents are employed. In that case, a composite product containing individual metal nanoparticles in a KCl matrix is obtained. The composite can be heated to at least 600 °C without significant agglomeration or growth in particle size. Washing the annealed product in the presence of catalyst supports in ethylene glycol removes the KCl and deposits the particles on the support. Six publications present the method and its application to producing and studying new catalyst/support combinations for fuel cell applications. Three publications concern the use of related methods to explore new lithium-sulfur battery concepts.

  18. Solvent exposure associated with single abasic sites alters the base sequence dependence of oxidation of guanine in DNA in GG sequence contexts.

    Science.gov (United States)

    Lee, Young-Ae; Liu, Zhi; Dedon, Peter C; Geacintov, Nicholas E; Shafirovich, Vladimir

    2011-07-25

    The effect of exposure of guanine in double-stranded oligonucleotides to aqueous solvent during oxidation by one-electron oxidants was investigated by introducing single synthetic tetrahydrofuran-type abasic sites (Ab) either adjacent to or opposite tandem GG sequences. The selective oxidation of guanine was initiated by photoexcitation of the aromatic sensitizers riboflavin and a pyrene derivative, and by the relatively small negatively charged carbonate radical anion. The relative rates of oxidation of the 5'- and 3' side G in runs of 5'⋅⋅⋅GG⋅⋅⋅ (evaluated by standard hot alkali treatment of the damaged DNA strand followed by high resolution gel electrophoresis of the cleavage fragments) are markedly affected by adjacent abasic sites either on the same or opposite strand. For example, in fully double-stranded DNA or one with an Ab adjacent to the 5'-G, the 5'-G/3'-G damage ratio is ≥4, but is inverted (<1.0) with the Ab adjacent to the 3'-G. These striking effects of Ab are attributed to the preferential localization of the "hole" on the most solvent-exposed guanine regardless of the size, charge, or reduction potential of the oxidizing species. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Characterization of the Interunit Bonds of Lignin Oligomers Released by Acid-Catalyzed Selective Solvolysis of Cryptomeria japonica and Eucalyptus globulus Woods via Thioacidolysis and 2D-NMR.

    Science.gov (United States)

    Saito, Kaori; Kaiho, Atsushi; Sakai, Ryo; Nishimura, Hiroshi; Okada, Hitomi; Watanabe, Takashi

    2016-12-07

    Acid-catalyzed degradation of lignin in toluene containing methanol selectively yields C6-C2 lignin monomers and releases lignin oligomers, a potential raw feedstock for epoxy resins. We herein characterize the structures of the lignin oligomers by focusing on the changes in the interunit linkage types during solvolysis. The oligomeric lignin products were analyzed via thioacidolysis and 2D-HSQC-NMR. The results show that lignin oligomers ranging from monomers to tetramers are released through considerable cleavage of the β-O-4 linkages. The lignin oligomers from Cryptomeria japonica (softwood) mainly comprise β-5, β-1, and tetrahydrofuran β-β linkages, whereas Eucalyptus globulus (hardwood) yields oligomers rich in β-1 and syringaresinol β-β linkages. Both wood samples exhibit selective release of β-β dimers and a relative decrease in 5-5 and 4-O-5 bonds during solvolysis. The method presented for the separation of lignin oligomers without β-O-4 linkages and with linkages unique to each wood species will be useful for the production of lignin-based materials.

  20. Rechargeable biofilm-controlling tubing materials for use in dental unit water lines.

    Science.gov (United States)

    Luo, Jie; Porteous, Nuala; Sun, Yuyu

    2011-08-01

    A simple and practical surface grafting approach was developed to introduce rechargeable N-halamine-based antimicrobial functionality onto the inner surfaces of continuous small-bore polyurethane (PU) dental unit waterline (DUWL) tubing. In this approach, tetrahydrofuran (THF) solution of a free-radical initiator, dicumyl peroxide (DCP), flowed through the PU tubing (inner diameter of 1/16 in., or 1.6 mm) to diffuse DCP into the tubing's inner walls, which was used as initiator in the subsequent grafting polymerization of methacrylamide (MAA) onto the tubing. Upon chlorine bleach treatment, the amide groups of the grafted MAA side chains were transformed into acyclic N-halamines. The reactions were confirmed with attenuated total reflectance infrared (ATR) spectra and iodometric titration. The mechanical properties of the tubing were not significantly affected by the grafting reactions. The biofilm-controlling function of the new N-halamine-based PU tubing was evaluated with Pseudomonas aeruginosa (P. aeruginosa), one of the most isolated water bacteria from DUWLs, in a continuous bacterial flow model. Bacteria culturing and SEM studies showed that the inner surfaces of the new N-halamine-based PU tubing completely prevented bacterial biofilm formation for at least three to four weeks. After that, bacteria began to colonize the tubing surface. However, the lost function was fully regenerated by exposing the tubing inner surfaces to diluted chlorine bleach. The recharging process could be repeated periodically to further extend the biofilm-controlling duration for long-term applications.

  1. Quantitative analysis of dimethyl titanocene by iodometric titration, gas chromatography and NMR.

    Science.gov (United States)

    Vailaya, A; Wang, T; Chen, Y; Huffman, M

    2001-06-01

    In this study we report the use of an automated iodometric titration method and a novel gas chromatography (GC) method for the quantitative analysis of dimethyl titanocene (DMT), a key raw material in drug synthesis. Both approaches are based on the reaction of DMT in toluene or tetrahydrofuran solutions with iodine. In the case of iodometric titration, excess iodine is titrated with a standardized aqueous sodium thiosulfate solution to a potentiometric end-point for the determination of DMT concentration. Alternatively, GC is employed to measure the concentration of iodomethane, a product of the reaction between DMT and iodine, in order to determine the concentration of DMT in the solution. Excellent agreement between iodometric titration, GC and NMR results using several DMT samples confirms the accuracy of the two methods and strongly supports the use of either method as a replacement to the expensive NMR for quantitative DMT analysis. The relatively few sources of error associated with the two methods, their ubiquitous nature and ease of application in routine analysis make them the analytical methods of choice, among all. Both methods have been validated according to ICH requirements. The use of iodometric titration method for DMT analysis is demonstrated with a couple of applications.

  2. DFT Studies on cis-1,4-Polymerization of Dienes Catalyzed by a Cationic Rare-Earth Metal Complex Bearing an Ancillary PNP Ligand

    Directory of Open Access Journals (Sweden)

    Xingbao Wang

    2017-02-01

    Full Text Available Dnsity functional theory (DFT calculations have been carried out for the highly selective cis-1,4-polymerization of butadiene catalyzed by a cationic rare-earth metal complex bearing an ancillary PNP ligand. It has been found that the chain initiation and propagation of butadiene polymerization occurs via the favorable cis-1,4-insertion route. The trans-1,4 and 1,2-insertion are unfavorable both kinetically and thermodynamically. The chain growth follows the π-allyl-insertion mechanism. The analyses of energy decomposition of transition states indicate that the likelihood of rival insertion pathways is predominantly controlled by the interaction energy of butadiene with a metal center and the deformation energy of butadiene moiety. The electronic factor of the central metal has a decisive influence on the cis- vs. trans-insertion and the regioselectivity (cis-1,4- vs. cis-1,2-insertion is mainly determined by steric hindrance. Tetrahydrofuran (THF coordination made monomer insertion less favorable compared with THF-free case and had more noticeable impact on the trans-monomer insertion compared with the cis case. During the chain propagation, cis-insertion of monomer facilitates THF de-coordination and the THF molecule could therefore dissociate from the central metal.

  3. Synthesis and optoelectronic properties of new polyarylates with 2-naphthyldiphenylamine units

    Science.gov (United States)

    Cai, Wanan; Wu, Xiaotong; Xiao, Tiandi; Niu, Haijun; Bai, Xuduo; Wang, Cheng; Wang, Wen; Zhang, Yanhong

    2018-02-01

    Herein, five kinds of soluble electrochromic polyarylates were synthesized from the reaction of N,N'-bis(4-carboxyphenyl)-N,N'-di-2-naphthyl-1,4-phenylenediamine with five bisphenols via direct polycondensation process, respectively. These new materials showed no significant decomposition below 400 °C in nitrogen atmosphere. The maximum UV-vis absorption bands of these polyarylates located at 328-348 nm and 327-353 nm for solid films and DMSO solution, respectively. The polyarylate 6a, as an example, exhibited not only aggregation-induced emission (AIE) effect in different fraction tetrahydrofuran/water solution, but also solvatochromism in various polar solvents, markedly. Two reversible pairs of distinct redox peaks were associated with noticeable color changed from original colorless to yellowish orange and green for polymeric film could be observed in the cyclic voltammetry (CV) test. New absorption peaks emerged in near-infrared (NIR) region with increasing voltage in the UV-vis spectra, which indicates these polyarylates can be used as NIR electrochromic materials. These polyarylates performed high contrast of optical transmittance change around 42-53% with the highest coloration efficiency up to 236 cm2C-1.

  4. Effect of minimizing amount of template by addition of macromolecular crowding agent on preparation of molecularly imprinted monolith.

    Science.gov (United States)

    Sun, Guang-Ying; Zhong, Dan-Dan; Li, Xiang-Jie; Luo, Yu-Qing; Ba, Hang; Liu, Zhao-Sheng; Aisa, Haji Akber

    2015-09-01

    One of the main challenges in the preparation of molecularly imprinted polymers (MIPs) is the substantial initial amount of template needed because of the requirement of high load capacities for most applications. A new strategy of macromolecular crowding was suggested to solve this problem by reducing the amount of template in the polymerization recipe. In a ternary porogenic system of polystyrene (PS) (crowding agent), tetrahydrofuran, and toluene, an imprinted monolithic column with high porosity and good permeability was synthesized using a mixture of ellagic acid (template), acrylamide, and ethylene glycol dimethacrylate. The effect of polymerization factors, including monomer-template molar ratio and the molecular weight and concentration of PS, on the imprinting effect of the resulting MIP monoliths was systematically investigated. At a high ratio of monomer-template (120:1), the greatest imprinting factor of 32.4 was obtained on the MIP monolith with the aid of macromolecular crowding agent. The PS-based imprinted monolith had imprinting even at the extremely high ratio of functional monomer to template of 1510:1. Furthermore, an off-line solid-phase extraction based on the ground MIP was conducted, and the purification recovery of ellagic acid from pomegranate-rind extract was up to 80 %. In conclusion, this approach based on macromolecular crowding is simple, and is especially valuable for those applications of MIP preparation for which a rare template is used.

  5. Imidazolium-functionalized poly(ether ether ketone) as membrane and electrode ionomer for low-temperature alkaline membrane direct methanol fuel cell

    Science.gov (United States)

    Yan, Xiaoming; Gu, Shuang; He, Gaohong; Wu, Xuemei; Benziger, Jay

    2014-03-01

    A series of imidazolium-functionalized poly(ether ether ketone)s (PEEK-ImOHs) were successfully synthesized by a two-step chloromethylation-Menshutkin reaction followed by hydroxide exchange. PEEK-ImOH membranes with ion exchange capacity (IEC) ranging from 1.56 to 2.24 mmol g-1 were prepared by solution casting. PEEK-ImOHs show selective solubility in aqueous solutions of acetone and tetrahydrofuran, but are insoluble in lower alcohols. PEEK-ImOH membranes with IEC of 2.03 mmol g-1 have high hydroxide conductivity (52 mS cm-1 at 20 °C), acceptable water swelling ratio (51% at 60 °C), and great tensile strength (78 MPa), and surprising flexibility (elongation-to-break of 168%), and high thermal stability (Decomposition temperature: 193 °C). In addition, PEEK-ImOH membranes show low methanol permeability (1.3-6.9 × 10-7 cm2 s-1). PEEK-ImOH membrane was tested in methanol/O2 fuel cell as both the HEM and the ionomer impregnated into the catalyst layer; the open circuit voltage is 0.84 V and the peak power density is 31 mW cm-2.

  6. Generation of powerful tungsten reductants by visible light excitation.

    Science.gov (United States)

    Sattler, Wesley; Ener, Maraia E; Blakemore, James D; Rachford, Aaron A; LaBeaume, Paul J; Thackeray, James W; Cameron, James F; Winkler, Jay R; Gray, Harry B

    2013-07-24

    The homoleptic arylisocyanide tungsten complexes, W(CNXy)6 and W(CNIph)6 (Xy = 2,6-dimethylphenyl, Iph = 2,6-diisopropylphenyl), display intense metal to ligand charge transfer (MLCT) absorptions in the visible region (400-550 nm). MLCT emission (λ(max) ≈ 580 nm) in tetrahydrofuran (THF) solution at rt is observed for W(CNXy)6 and W(CNIph)6 with lifetimes of 17 and 73 ns, respectively. Diffusion-controlled energy transfer from electronically excited W(CNIph)6 (*W) to the lowest energy triplet excited state of anthracene (anth) is the dominant quenching pathway in THF solution. Introduction of tetrabutylammonium hexafluorophosphate, [Bu(n)4N][PF6], to the THF solution promotes formation of electron transfer (ET) quenching products, [W(CNIph)6](+) and [anth](•-). ET from *W to benzophenone and cobalticenium also is observed in [Bu(n)4N][PF6]/THF solutions. The estimated reduction potential for the [W(CNIph)6](+)/*W couple is -2.8 V vs Cp2Fe(+/0), establishing W(CNIph)6 as one of the most powerful photoreductants that has been generated with visible light.

  7. Docking Studies and Anti-inflammatory Activity of β-Hydroxy-β-arylpropanoic Acids

    Directory of Open Access Journals (Sweden)

    Ivan O. Juranic

    2008-03-01

    Full Text Available The article describes a two-step synthesis of diastereomeric 3-hydroxy-2-methyl-3-(4-biphenylylbutanoic acids. In the first step an intermediate α-bromo propanoicacid 1-ethoxyethyl ester was synthesized. The second step is a new modified Reformatskyreaction in presence of Zn in tetrahydrofuran (THF at –5 to 10 °C between the previouslysynthesized intermediate and 4-acetylbiphenyl. Synthesis of the other studied β-hydroxy-β-arylpropanoic acids has already been reported. These β-hydroxy-β-arylpropanoic acidsbelong to the arylpropanoic acid class of compounds, structurally similar to the NSAIDssuch as ibuprofen. The anti-inflammatory activity and gastric tolerability of thesynthesized compounds were evaluated. Molecular docking experiments were carried outto identify potential COX-2 inhibitors among the β-hydroxy-β-aryl-alkanoic acids class.The results indicate that all compounds possess significant anti-inflammatory activity afteroral administration and that the compounds 2-(9-(9-hydroxy-fluorenyl-2-methylpropanoic acid (5 and 3-hydroxy-3,3-diphenyl-propanoic acid (3 possess thestrongest anti-inflammatory activity, comparable to that of ibuprofen, a standard NSAID,and that none of tested substances or ibuprofen produced any significant gastric lesions.

  8. Effect of mobile phase composition on the retention of selected alkaloids in reversed-phase liquid chromatography with chaotropic salts.

    Science.gov (United States)

    Flieger, J

    2007-12-21

    Sodium hexafluorophosphate, perchlorate and trifluoroacetate were applied as ion-ion interaction reagents in reversed-phase liquid chromatography. The separation of chosen alkaloids was performed by changing the kind of the organic modifier (methanol, acetonitrile, tetrahydrofuran), concentration of the ion-ion-interaction reagents and the concentration of phosphate buffer at constant pH (2.7) in the mobile phase. Obtained results were analyzed in connection to a dynamic ion-exchange model of retention and ion-ion interaction effects. The perturbation method was applied to test proposed retention theories. The formation of ion-complexes controlling the retention in chaotropic systems was confirmed. On the basis of the relationships of capacity factors (k) versus salt concentrations derived experimentally, absolute increases in capacity factors, the desolvation parameters and the limiting retention factors were calculated and compared for all the investigated compounds in eluent systems studied. The selectivity of the proposed mobile phases was compared on the basis of the separation of alkaloid mixture.

  9. Synthesis, structural characterization and dielectric behavior of new oxime-cyclotriphosphazene derivatives

    Science.gov (United States)

    Koran, Kenan; Özen, Furkan; Biryan, Fatih; Görgülü, Ahmet Orhan

    2016-02-01

    The cyclotriphosphazene compound (2) bearing formyl groups as side groups was obtained from the reaction of 2,2-Dichloro-4,4,6,6-bis[spiro(2‧,2″-dioxy-1‧,1″-biphenylyl)]cyclotriphosphazene (1) with 4-hydroxy-3-methoxybenzaldehyde in the presence K2CO3 in tetrahydrofuran. Oxime-cyclotriphosphazene compound (3) was synthesized from the reaction of compound 2 with hydroxylamine hydrochloride in pyridine. The synthesized oxime-phosphazene compound (3) was reacted with alkyl and acyl halides. As a results, the cyclotriphosphazene compounds (1-10) bearing oxime ether and ester as side groups were obtained. The chemical structures of these compounds (1-10) were determined by elemental analysis, FT-IR, 1H, 13C and 31P NMR spectroscopic methods. Dielectric constant, dielectric loss factors and conductivity properties of cyclotriphosphazene compounds were measured over the frequency range from 100 Hz to 2 kHz at 25 °C and compared with each other. It is found that ester substituted cyclotriphosphazenes have higher dielectric constant. Our study suggests that these phosphazenes promising candidate materials in multifunctional optoelectronic devices.

  10. Femtosecond time-resolved photophysics of 1,4,5,8-naphthalene diimides.

    Science.gov (United States)

    Ganesan, Palaniswamy; Baggerman, Jacob; Zhang, Hong; Sudhölter, Ernst J R; Zuilhof, Han

    2007-07-19

    The photophysical properties of a tetrahedral molecule with naphthalene diimide (NDI) moieties and of two model compounds were investigated. The absorption and fluorescence spectra of dialkyl-substituted NDI are in agreement with literature. While the absorption spectra of phenyl-substituted molecules are similar to all other NDIs, their fluorescence showed a broad band between 500 and 650 nm. This band is sensitive to the polarity of the solvent and is attributed to a CT state. The absorption spectra and lifetime (10+/-2 ps) of the electronically excited singlet state of a dialkyl-substituted NDI was determined by femtosecond transient absorption spectroscopy, and the latter was confirmed by picosecond fluorescence spectroscopy. Nanosecond flash photolysis showed the subsequent formation of the triplet state. The presence of a phenyl substituent on the imide nitrogen of NDI resulted in faster deactivation of the singlet state (lifetime 0.5-1 ps). This is attributed to the formation of a short-lived CT state, which decays to the local triplet state. The faster deactivation was confirmed by fluorescence lifetime measurements in solution and in a low-temperature methyl-tetrahydrofuran glass.

  11. Using Photosensitive Dye To Improve Multi Walled Carbon Nanotubes Dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Costanzo, Guadalupe; Goyanes, Silvia [Laboratorio de PolImeros y Materiales Compuestos, Dpto. de Fisica, FCEyN, Universidad de Buenos Aires (Argentina) (Argentina); Ledesma, Silvia, E-mail: ledesma@df.uba.ar [Laboratorio de Procesado de Imagenes, Dpto. de Fisica, FCEyN, Universidad de Buenos Aires (Argentina) (Argentina)

    2011-01-01

    As already well-known, the outstanding mechanical and electrical properties of carbon nanotubes (CNT) are partially lost when CNT aggregate. The fact that CNT tend to aggregate makes difficult to put them into a host matrix, for example. Until now, achieving stable dispersions of CNT is still a challenge. In the present work, we show that the addition of an azobenzene derivative, Disperse Orange 3 (DO3) to dispersions of multi walled carbon nanotubes (MWCNT) in the organic solvent tetrahydrofuran (THF) efficiently helps debundling MWCNT and makes dispersions stable for days. We report UV-Vis optical absorption experiments that suggest an interaction between MWCNT and DO3 molecules following the behavior qualitatively observed. Dispersions with MWCNT and DO3 in THF were observed qualitatively over time. Successful suspensions (for the higher DO3 concentrations studied) were stable for several days. Also, we prepared polymeric films doped with MWCNT non-covalent functionalized with DO3 in one of the proper DO3/MWCNT weight relation where stable supensions were obtained. In this study we show preliminary results where the optical response of these samples was also measured.

  12. Development of Low Energy Gap and Fully Regioregular Polythienylenevinylene Derivative

    Directory of Open Access Journals (Sweden)

    Tanya M. S. David

    2014-01-01

    Full Text Available Low energy gap and fully regioregular conjugated polymers find its wide use in solar energy conversion applications. This paper will first briefly review this type of polymers and also report synthesis and characterization of a specific example new polymer, a low energy gap, fully regioregular, terminal functionalized, and processable conjugated polymer poly-(3-dodecyloxy-2,5-thienylene vinylene or PDDTV. The polymer exhibited an optical energy gap of 1.46 eV based on the UV-vis-NIR absorption spectrum. The electrochemically measured highest occupied molecular orbital (HOMO level is −4.79 eV, resulting in the lowest unoccupied molecular orbital (LUMO level of −3.33 eV based on optical energy gap. The polymer was synthesized via Horner-Emmons condensation and is fairly soluble in common organic solvents such as tetrahydrofuran and chloroform with gentle heating. DSC showed two endothermic peaks at 67°C and 227°C that can be attributed to transitions between crystalline and liquid states. The polymer is thermally stable up to about 300°C. This polymer appears very promising for cost-effective solar cell applications.

  13. Solvate Structures and Computational/Spectroscopic Characterization of LiBF4 Electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Seo, D. M.; Boyle, Paul D.; Allen, Joshua L.; Han, Sang D.; Jonsson, Erlendur; Johansson, Patrik; Henderson, Wesley A.

    2014-07-21

    Crystal structures have been determined for both LiBF4 and HBF4 solvates—(acetonitrile)2:LiBF4, (ethylene glycol diethyl ether)1:LiBF4, (diethylene glycol diethyl ether)1:LiBF4, (tetrahydrofuran)1:LiBF4, (methyl methoxyacetate)1:LiBF4, (suc-cinonitrile)1:LiBF4, (N,N,N',N",N"-pentamethyldiethylenetriamine)1:HBF4, (N,N,N',N'-tetramethylethylenediamine)3/2:HBF4 and (phenanthroline)2:HBF4. These, as well as other known LiBF4 solvate structures, have been characterized by Raman vibrational spectroscopy to unambiguously assign the anion Raman band positions to specific forms of BF4-...Li+ cation coordination. In addition, complementary DFT calculations of BF4-...Li+ cation complexes have provided additional insight into the challenges associated with accurately interpreting the anion interactions from experimental Raman spectra. This information provides a crucial tool for the characterization of the ionic association interactions within electrolytes.

  14. Effect of pretreating of host oil on coprocessing. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Wender, I.; Tierney, J.W.

    1995-10-01

    A petroleum vacuum resid (1,000 F+) was pretreated by catalytic hydrogenation and hydrocracking reactions and the pretreated resids (host oils) were then coprocessed with coal. The fraction of coal converted to soluble products and the yield of pentane-soluble oils were determined after coprocessing. The phenolic oxygen concentration of the oil product provided a means for estimating the fraction of coal liquids in the products; oils originating from coal had much higher concentrations of phenolic oxygen than those originating from petroleum. Resids that were pretreated by mild temperature hydrogenation reactions, where cracking was suppressed, became better host oils; when these pretreated resids were coprocessed with coal, more of the mixture was converted to tetrahydrofuran-soluble products. Depending on the pretreatment, the pentane-soluble oil yields following thermal coprocessing were either significantly lower or slightly higher than the oil yields obtained with untreated resid. The yield of oils was strongly affected by the concentration of coal in the feed. The presence of small amounts, less than 33% of coal, enhanced the conversion of petroleum resid to oils during coprocessing, although the increases were small. 91 refs.

  15. Electrochemical Properties and Speciation in Mg(HMDS)2-Based Electrolytes for Magnesium Batteries as a Function of Ethereal Solvent Type and Temperature.

    Science.gov (United States)

    Merrill, Laura C; Schaefer, Jennifer L

    2017-09-19

    Magnesium batteries are a promising alternative to lithium-ion batteries due to the widespread abundance of magnesium and its high specific volumetric energy capacity. Ethereal solvents such as tetrahydrofuran (THF) are commonly used for magnesium-ion electrolytes due to their chemical compatibility with magnesium metal, but the volatile nature of THF is a concern for practical application. Herein, we investigate magnesium bis(hexamethyldisilazide) plus aluminum chloride (Mg(HMDS)2-AlCl3) electrolytes in THF, diglyme, and tetraglyme at varying temperature. We find that, despite the higher thermal stability of the glyme-based electrolytes, THF-based electrolytes have better reversibility at room temperature. Deposition/stripping efficiency is found to be a strong function of temperature. Diglyme-based Mg(HMDS)2-AlCl3 electrolytes are found to not exchange as quickly as THF and tetraglyme, stabilizing AlCl2+ and facilitating undesired aluminum deposition. Raman spectroscopy, 27Al NMR, and mass spectrometry are used to identify solution speciation.

  16. Reactive phase inversion for manufacture of asymmetric poly (ether imide sulfone) membranes

    KAUST Repository

    Jalal, Taghreed

    2014-12-01

    Poly (ether imide sulfone) membranes were manufactured by combining phase inversion and functionalization reaction between epoxy groups and amine modified polyether oligomers (Jeffamine) or TiO2 nanoparticles. Polysilsesquioxanes containing epoxy functionalities were in-situ grown in the casting solution and made available for further reaction with amines in the coagulation/annealing baths. The membranes were characterized by field emission scanning electron microscopy, porosimetry and water flux measurements. Water permeances up to 1500 l m-2 h-1 bar-1 were obtained with sharp pore size distribution and a pore diameter peak at 66 nm, confirmed by porosimetry, which allowed 99.2% rejection of γ-globulin. Water flux recovery of 77.5% was achieved after filtration with proteins. The membranes were stable in 50:50 dimethylformamide/water, 50:50 N-methyl pyrrolidone/water and 100% tetrahydrofuran. The possibility of using similar concept for homogeneous and stable attachment of nanoparticles on the membrane surface was demonstrated.

  17. Molecular and electronic structures of the members of the electron transfer series [Mn(bpy)3]n (n = 2+, 1+, 0, 1-) and [Mn(tpy)2]m (m = 4+, 3+, 2+, 1+, 0). An experimental and density functional theory study.

    Science.gov (United States)

    Wang, Mei; England, Jason; Weyhermüller, Thomas; Wieghardt, Karl

    2014-02-17

    The members of the electron transfer series [Mn(bpy)3](n) (n = 2+, 1+, 0, 1-) and [Mn(tpy)2](m) (m = 2+, 1+, 0) have been investigated using a combination of magnetochemistry, electrochemistry, and UV-vis-NIR spectroscopy; and X-ray crystal structures of [Mn(II)((Me)bpy(•))2((Me)bpy(0))](0), [Li(THF)4][Mn(II)(bpy(•))3], and [Mn(II)(tpy(•))2](0) have been obtained (bpy = 2,2'-bipyridine; (Me)bpy = 4,4'-dimethyl-2,2'-bipyridine; tpy = 2,2':6,2″-terpyridine; THF = tetrahydrofuran). It is the first time that the latter complex has been isolated and characterized. Through these studies, the electronic structures of each member of both series of complexes have been elucidated, and their molecular and electronic structures further corroborated by broken symmetry (BS) density functional theoretical (DFT) calculations. It is shown that all one-electron reductions that comprise the aforementioned redox series are ligand-based. Hence, all species contain a central high-spin Mn(II) ion (SMn = 5/2). In contrast, the analogous series of Tc(II) and Re(II) complexes possess low-spin electron configurations.

  18. Enzyme catalysis in organic solvents: influence of water content, solvent composition and temperature on Candida rugosa lipase catalyzed transesterification.

    Science.gov (United States)

    Herbst, Daniela; Peper, Stephanie; Niemeyer, Bernd

    2012-12-31

    In the present study the influence of water content, solvent composition and reaction temperature on the transesterification of 1-phenylpropan-2-ol catalyzed by Candida rugosa lipase was examined. Reactions were carried out in different mixtures of hexane and tetrahydrofurane. The studies showed that an increasing water content of the organic solvent results in an increasing enzyme activity and a decreasing enantiomeric excess. Furthermore, a significant influence of the solvent hydrophilicity both on the enzyme activity and on the enantiomeric excess was found. An increase in solvent hydrophilicity leads to a decrease of enzyme activity and an increase of the enantiomeric excess. This indicates that the enzyme becomes more selective with decreasing flexibility. Similar effects were found by variation of the reaction temperature. Taken together, the decrease in conversion and the increase in selectivity with increasing solvent hydrophilicity are induced by the different water contents on the enzyme surface and not by the solvent itself. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Final technical report, Volume 2 - hydrogenative and hydrothermal pretreatments and spectroscopic characterization using pyrolysis-GC-MS, CPMAS {sup 13}C NMR and FT-IR

    Energy Technology Data Exchange (ETDEWEB)

    Chunshan Song; Hatcher, P.G.; Saini, A.K.; Wenzel, K.A.

    1998-01-01

    It has been indicated by DOE COLIRN panel that low-temperature catalytic pretreatment is a promising approach to the development of an improved liquefaction process. This work is a fundamental study on effects of pretreatments on coal structure and reactivity in liquefaction. The main objectives of this project are to study the coal structural changes induced by low-temperature catalytic and thermal pretreatments by using spectroscopic techniques; and to clarify the pretreatment-induced changes in reactivity or convertibility of coals. As the second volume of the final report, here we summarize our work on spectroscopic characterization of four raw coals including two subbituminous coals and two bituminous coals, tetrahydrofuran (THF)-extracted but unreacted coals, the coals (THF-insoluble parts) that have been thermally pretreated. in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent, and the coals (THF-insoluble parts) that have been catalytically pretreated in the presence of a dispersed Mo sulfide catalyst in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent.

  20. Silicon-carbon composite dispersed in a carbon paper substrate for solid polymer lithium-ion batteries

    Science.gov (United States)

    Si, Q.; Kawakubo, M.; Matsui, M.; Horiba, T.; Yamamoto, O.; Takeda, Y.; Seki, N.; Imanishi, N.

    2014-02-01

    Carbon coated silicon (Si/C) dispersed in a carbon paper (CP) was examined as the anode for solid polymer lithium-ion batteries. The CP was prepared by pyrolysis of poly(acrylonitrile) fiber and Manila hemp non-woven cloth at 2600 °C under an inert atmosphere. The Si/C composite was formed by pyrolysis of a slurry consisting of Si power and a solution of polyvinyl chloride in tetrahydrofuran as the carbon source. Si/C:CP with a weight ratio of 20:100 had a high initial capacity of 980 mAh g-1 of Si/C and a high initial columbic efficiency of 77%, and also exhibited excellent capacity retention with a reversible capacity of 710 mAh g-1 of Si/C even after 250 cycles at a charge and discharge rate of 0.1 A g-1. The carbon fiber framework in the carbon paper could adsorb the volume change of Si during the lithium insertion and stripping processes.

  1. Multicomponent Matrimid Membrane for Gas Separation

    KAUST Repository

    Irerua, Olayinka

    2012-07-01

    Matrimid was utilized for the preparation of membranes with asymmetric structures. A combination of well-known solvents for Matrimid which include 1- methyl-2-Pyrrolidone (NMP), tetrahydrofuran (THF), dichloromethane, tetrachloroethane as well as non-solvents n-butanol, xylene, and acetic acid were used. Cast solutions were prepared at room temperature for different combinations and compositions of polymer/solvent/non-solvent systems. PEG and Octa-(amino phenyl) POSS were introduced in some of the cast solutions. The membranes obtained were characterized by permeation test for gas permeabilities and selectivities, Scanning Electron Microscopy (SEM) and Nuclear Magnetic Resonance (NMR) Spectroscopy. The gas permeation test showed that the use of mixture of dichloromethane and tetrachloroethane as solvents with xylene non-solvent and acetic acid as stabilizer gave membranes with very high gas selectivity of 133 for CO2/N2 and 492 for CO2/CH4. Also, cast solutions containing PEG resulted in membranes with slightly enhanced selectivities from 30 to 42 for CO2/N2. Permeation results for CO2, N2 and H2 and the selectivities for gas pairs such as CO2/N2, CO2/CH4, are discussed in relation to the effect of pressure on the membrane permeance, they are also compared with existing results.

  2. Exfoliation of Reduced Graphene Oxide with Self-Assembled π-Gelators for Improved Electrochemical Performance.

    Science.gov (United States)

    Vedhanarayanan, Balaraman; Babu, Binson; Shaijumon, Manikoth M; Ajayaghosh, Ayyappanpillai

    2017-06-14

    Among several methodologies to improve the solution processing of graphene-based materials, noncovalent functionalization has been considered as the simplest and nondestructive method. Herein, we show that molecular self-assembly process can be used as a useful tool to exfoliate reduced graphene oxide (RGO), resulting in hybrid materials with improved physical properties. Upon interacting with a π-gelator, the dispersing ability of the RGO increased significantly in most of nonpolar and polar aprotic solvents when compared to the bare one. The amount of RGO dispersed was 1.7-1.8 mg mL -1 in solvents such as toluene, o-dichlorobenzene (ODCB) and tetrahydrofuran (THF). Morphological studies revealed that aggregation of π-gelator over RGO helps to exfoliate graphene layers to remain as individual sheets with higher surface area. Experimental studies revealed enhanced surface area (250 m 2 g -1 ) and better conductivity (3.7 S m -1 ) of the hybrid materials with 30% of RGO content resulting in excellent electrochemical performance (specific capacitance of 181 F g -1 ) as electrodes for supercapacitors.

  3. Eluent Tolerance and Enantioseparation Recovery of Chiral Packing Materials Based on Chitosan Bis(Phenylcarbamate-(n-Octyl Ureas for High Performance Liquid Chromatography

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2016-11-01

    Full Text Available The goal of the present work was to study the influence of the swelling of chitosan derivatives on the enantioseparation and the separation performance recovery of chiral stationary phases (CSPs based on these derivatives. Therefore, six chitosan bis(phenylcarbamate-(n-octyl ureas were synthesized, which were coated on macroporous 3-aminopropyl silica gel affording new CSPs. Most of the CSPs demonstrated strong enantioseparation capability for the tested chiral compounds. The swelling capacity of the chitosan bis(phenylcarbamate-(n-octyl ureas in ethyl acetate, acetone and tetrahydrofuran (THF was evaluated. Among the chitosan derivatives, the chitosan bis(3,5-dichlorophenylcarbamate-(n-octyl urea polymer showed the highest swelling capacity in ethyl acetate and THF. The polymer-based CSPs could be utilized with pure ethyl acetate and a normal phase containing 70% THF, but was damaged by pure THF. On the other hand, the separation performance of the damaged CSP could be recovered after it was allowed to stand for a period of time. The observations are important for the development and application of polysaccharide derivative-based CSPs.

  4. In situ synthesis and characterization of hydroxyapatite/natural rubber composites for biomedical applications.

    Science.gov (United States)

    Dick, T A; Dos Santos, L A

    2017-08-01

    In this work, a biomimetic synthesis reaction for the production of hydroxyapatite (HA)/natural rubber (NR) composites is presented. HA was synthesized in the presence of solubilized NR in tetrahydrofuran (THF), which permits that negatively charged domains in proteins and lipids in NR work as nucleation sites for hydroxyapatite. The mechanical and physicochemical properties of composites containing 10, 20 and 30wt% HA were studied. NR influenced HA crystallite morphology, shape and size and was able to disperse the HA particles in THF. The dispersion of HA in the composites promoted the enhancement of mechanical properties and loss of solubility of composites, which is believed to be macroscopic manifestations of the physical adsorption of NR to HA particles, known as the bound rubber phenomenon. Preliminary cell studies indicated that HepG2 cells presented viabilities ranging from 71.6 to 91.3%, with cell proliferation positively influenced by HA content at shorter culture times. The good dispersion of HA in the composites is expected to improve NR bioactivity and direct its use towards bone applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Polymer Vesicles as Robust Scaffolds for the Directed Assembly of Highly Crystalline Nanocrystals †

    KAUST Repository

    Wang, Mingfeng

    2009-12-15

    We report the incorporation of various inorganic nanoparticles (NPs) (PbS, LaOF, LaF3, and TiO2, each capped by oleic acid, and CdSe/ZnS core/shell QDs capped by trioctylphosphine oxide) into vesicles (d = 70-150 nm) formed by a sample of poly(styrene-b-acrylic acid) (PS4o4-b-PAA 62, where the subscripts refer to the degree of polymerization) in mixtures of tetrahydrofuran (THF), dioxane, and water. The block copolymer formed mixtures of crew-cut micelles and vesicles with some enhancement of the vesicle population when the NPs were present. The vesicle fraction could be isolated by selective sedimentation via centrifugation, followed by redispersion in water. The NPs appeared to be incorporated into the PAA layers on the internal and external walls of the vesicles (strongly favoring the former). NPs on the exterior surface of the vesicles could be removed completely by treating the samples with a solution of ethylenediaminetetraacetate (EDTA) in water. The triangular nanoplatelets of LaF3 behaved differently. Stacks of these platelets were incorporated into solid colloidal entities, similar in size to the empty vesicles that accompanied them, during the coassembly as water was added to the polymer/LaF3/THF/ dioxane mixture. © 2009 American Chemical Society.

  6. High Ultraviolet Absorption in Colloidal Gallium Nanoparticles Prepared from Thermal Evaporation

    Directory of Open Access Journals (Sweden)

    Flavio Nucciarelli

    2017-07-01

    Full Text Available New methods for the production of colloidal Ga nanoparticles (GaNPs are introduced based on the evaporation of gallium on expendable aluminum zinc oxide (AZO layer. The nanoparticles can be prepared in aqueous or organic solvents such as tetrahydrofuran in order to be used in different sensing applications. The particles had a quasi mono-modal distribution with diameters ranging from 10 nm to 80 nm, and their aggregation status depended on the solvent nature. Compared to common chemical synthesis, our method assures higher yield with the possibility of tailoring particles size by adjusting the deposition time. The GaNPs have been studied by spectrophotometry to obtain the absorption spectra. The colloidal solutions exhibit strong plasmonic absorption in the ultra violet (UV region around 280 nm, whose width and intensity mainly depend on the nanoparticles dimensions and their aggregation state. With regard to the colloidal GaNPs flocculate behavior, the water solvent case has been investigated for different pH values, showing UV-visible absorption because of the formation of NPs clusters. Using discrete dipole approximation (DDA method simulations, a close connection between the UV absorption and NPs with a diameter smaller than ~40 nm was observed.

  7. Crystal structures of three complexes of zinc chloride with tri-tert-butylphosphane

    Directory of Open Access Journals (Sweden)

    Aaron D. Finke

    2016-01-01

    Full Text Available Under anhydrous conditions and in the absence of a Lewis-base solvent, a zinc chloride complex with tri-tert-butylphosphane as the μ-bridged dimer is formed, viz. di-μ-chlorido-bis[chloridobis(tri-tert-butylphosphanezinc], [ZnCl4(C12H27P2], (1, which features a nearly square-shaped (ZnCl2 cyclic core and whose Cl atoms interact weakly with C—H groups on the phosphane ligand. In the presence of THF, monomeric dichlorido(tetrahydrofuran-κO(tri-tert-butylphosphane-κPzinc, [ZnCl2(C4H8O(C12H27P] or [P(tBu3(THFZnCl2], (2, is formed. This slightly distorted tetrahedral Zn complex has weak C—H...Cl interactions between the Cl atoms and phosphane and THF C—H groups. Under ambient conditions, the hydrolysed complex tri-tert-butylphosphonium aquatrichloridozincate 1,2-dichloroethane monosolvate, (C12H28P[ZnCl3(H2O]·C2H4Cl2 or [HPtBu3]+ [(H2OZnCl3]−·C2H4Cl2, (3, is formed. This complex forms chains of [(H2OZnCl3]− anions from hydrogen-bonding interactions between the water H atoms and Cl atoms that propagate along the b axis.

  8. A fast response hafnium selective polymeric membrane electrode based on N,N'-bis(alpha-methyl-salicylidene)-dipropylenetriamine as a neutral carrier.

    Science.gov (United States)

    Rezaei, B; Meghdadi, S; Zarandi, R Fazel

    2008-08-30

    In this study a new hafnium selective sensor was fabricated from polyvinylchloride (PVC) matrix membrane containing neutral carrier N,N'-bis(alpha-methyl-salicylidene)-dipropylenetriamine (Mesaldpt) as a new ionophore, sodium tetraphenyl borate (NaTPB) as anionic discriminator and dioctyl phthalate (DOP) as plasticizing solvent mediator in tetrahydrofuran solvent. The electrode exhibits Nernstian response for Hf(4+) (Hafnium(IV)) over a wide concentration range (2.0 x 10(-7) to 1.0 x 10(-1)M) with the determination coefficient of 0.9966 and slope of 15.1+/-0.1 mVdecades(-1). The limit of detection is 1.9 x 10(-7)M. The electrode has a fast response time of 18s and a working pH range of 4-8. The proposed membrane shows excellent discriminating ability towards Hf(4+) ion with regard to several alkali, alkaline earth transition and heavy metal ions. It can be used over a period of 1.5 months with good reproducibility. It is successfully applied for direct determination of Hf(4+) in solutions by standard addition method for real sample analysis.

  9. Effect of polymer concentration on the morphology and mechanical characteristics of electrospun cellulose acetate and poly (vinyl chloride nanofiber mats

    Directory of Open Access Journals (Sweden)

    Bethwel Tarus

    2016-09-01

    Full Text Available Cellulose Acetate (CA and Poly (Vinyl Chloride (PVC nanofiber mats were electrospun into nanofibers. The morphology and mechanical properties of nanofiber mats were evaluated versus different solution concentrations. Solutions were prepared in mixed solvent systems of 2:1 (w/w Acetone/N,N-Dimethylacetamide (DMAc and 3:2 (w/w Acetone/N,N-Dimethylformamide (DMF for CA and 1:1 (w/w Tetrahydrofuran/DMF for PVC. Scanning electron microscopy (SEM images revealed that a beaded fibrous structure could be electrospun beginning at 10% CA in both Acetone/DMAc and Acetone/DMF solvent systems. The experimental results showed that smooth fibers were achievable at 14% CA in Acetone/DMAc and at 16% CA in Acetone/DMF solvent systems. For PVC, beaded fibers were formed at 12% PVC and smooth fibers were formed beginning at 14% PVC. Tensile strength tests showed that mechanical properties of the nonaligned nanofiber mats were influenced by solution concentration. With increasing solution concentration, the tensile strengths, break strains and initial moduli of the CA nanofiber mats increased. The effect of solution concentration on the tensile strengths of nanofiber mats was quite significant while it did not have any considerable effect on the tensile properties of the cast films.

  10. Effect of molecular conformation on the mechanofluorochromic properties based on DDIF

    Science.gov (United States)

    Mai, Runsheng; Peng, Huojun; Meng, Yuying; Chang, Xinyue; Jiang, Yue; Gao, Jinwei; Zhou, Guofu; Liu, Jun-ming

    2017-07-01

    Mechanofluorochromic (MFC) materials are smart materials in that their absorption and/or emission can respond to mechanical stimuli. They have received much attention recently. Although there have been several new material systems designed, little work has been done regarding the influence of molecular conformation on MFC properties. Herein, to disclose the relationship between molecular conformation and MFC properties, two molecules based on a 6, 12-Dihydro-6, 12-diaza-indeno[1,2-b]fluorine (DDIF) building block with thienyl linker, BDDIF-Th and BDDIF-BTh, have been designed and synthesized. Optical and electrochemical properties have been studied by UV-vis spectrometer and cyclic voltammetry measurements. Weak aggregation-induced emission (AIE) phenomena were obtained in the tetrahydrofuran (THF)/water solution. MFC behaviors suggest that BDDIF-Th is more sensible to the external mechanical forces than BDDIF-BTh. The color change could be attributed to the appearance of new emission peak instead of a bathochromic or hypsochromic effect. Theoretical calculations reveal that MFC performance is highly related to the molecular conformation, meaning that the BDDIF-BTh with perpendicular conformation is more difficult to flatten than the comparatively planar BDDIF-Th.

  11. Effect of molecular weight on the electrophoretic deposition of carbon black nanoparticles in moderately viscous systems.

    Science.gov (United States)

    Modi, Satyam; Panwar, Artee; Mead, Joey L; Barry, Carol M F

    2013-08-06

    Electrophoretic deposition from viscous media has the potential to produce in-mold assembly of nanoparticles onto three-dimensional parts in high-rate, polymer melt-based processes like injection molding. The effects of the media's molecular weight on deposition behavior were investigated using a model system of carbon black and polystyrene in tetrahydrofuran. Increases in molecular weight reduced the electrophoretic deposition of the carbon black particles due to increases in suspension viscosity and preferential adsorption of the longer polystyrene chains on the carbon black particles. At low deposition times (≤5 s), only carbon black deposited onto the electrodes, but the deposition decreased with increasing molecular weight and the resultant increases in suspension viscosity. For longer deposition times, polystyrene codeposited with the carbon black, with the amount of polystyrene increasing with molecular weight and decreasing with greater charge on the polystyrene molecules. This deposition behavior suggests that use of lower molecular polymers and control of electrical properties will permit electrophoretic deposition of nanoparticles from polymer melts for high-rate, one-step fabrication of nano-optical devices, biochemical sensors, and nanoelectronics.

  12. Comparison of different tissue clearing methods and 3D imaging techniques for visualization of GFP-expressing mouse embryos and embryonic hearts.

    Science.gov (United States)

    Kolesová, Hana; Čapek, Martin; Radochová, Barbora; Janáček, Jiří; Sedmera, David

    2016-08-01

    Our goal was to find an optimal tissue clearing protocol for whole-mount imaging of embryonic and adult hearts and whole embryos of transgenic mice that would preserve green fluorescent protein GFP fluorescence and permit comparison of different currently available 3D imaging modalities. We tested various published organic solvent- or water-based clearing protocols intended to preserve GFP fluorescence in central nervous system: tetrahydrofuran dehydration and dibenzylether protocol (DBE), SCALE, CLARITY, and CUBIC and evaluated their ability to render hearts and whole embryos transparent. DBE clearing protocol did not preserve GFP fluorescence; in addition, DBE caused considerable tissue-shrinking artifacts compared to the gold standard BABB protocol. The CLARITY method considerably improved tissue transparency at later stages, but also decreased GFP fluorescence intensity. The SCALE clearing resulted in sufficient tissue transparency up to ED12.5; at later stages the useful depth of imaging was limited by tissue light scattering. The best method for the cardiac specimens proved to be the CUBIC protocol, which preserved GFP fluorescence well, and cleared the specimens sufficiently even at the adult stages. In addition, CUBIC decolorized the blood and myocardium by removing tissue iron. Good 3D renderings of whole fetal hearts and embryos were obtained with optical projection tomography and selective plane illumination microscopy, although at resolutions lower than with a confocal microscope. Comparison of five tissue clearing protocols and three imaging methods for study of GFP mouse embryos and hearts shows that the optimal method depends on stage and level of detail required.

  13. Effects of silica content on the formation and morphology of ENR/PVC/Silica composites beads

    Science.gov (United States)

    Abdullah, Nurul Amni; Tahiruddin, Nordiana Suhada Mohmad; Othaman, Rizafizah

    2017-05-01

    The effects of silica content in preparing silica-filled epoxidized natural rubber/polyvinyl chloride (ENR/PVC) beads were investigated. ENR/PVC matrix blend used was of composition 60% (ENR50) and 40% (PVC) by weight. The matrix blend was then dissolved in tetrahydrofuran (THF) by sol-gel technique prior to addition of silica fume as filler at varying amounts up to 25 wt% of the matrix mass. The composites beads were formed via phase inversion method by dropping the polymeric solution into a non-solvent. The size and shape were improved by adding in an increased amount of silica. Morphological studies showed distinct features of beads' surface in terms of homogeneity of silica particle distribution and presence of agglomerations and voids within the ENR/PVC matrix. Formation of silica network was apparent on the bead at 25 wt% silica content. The bead formation was found to be significantly affected by the silica loading in the ENR/PVC solution.

  14. Low frequency dielectric dispersion study of PVC-PPy blends in dilute solution of different solvents

    Science.gov (United States)

    Sharma, Deepika; Tripathi, Deepti

    2017-05-01

    In present study,the effect of adding Polypyrrole (PPy), a conductive polymer, on the dielectric and electrical behavior of Polyvinyl chloride (PVC) in dilute solution of moderate polar solvent Tetrahydrofuran (THF) and polar solvent M-Cresol at low frequency is investigated. The blend of PVC with PPy forms a colloidal solution in both the solvents. The dielectric dispersion study of PVC-PPy blends in THF and M-Cresol has been carried out in the frequency range of 20Hz to 2MHz at temperature of 303 K. The influence of solvent on dielectric and electrical parameters such as dielectric constant [ɛ*(ω)], loss tangent (tan δ) and ac conductivity (σac) of PVC - PPy solutions is studied. At low frequencies, electrode polarization seems to have dominant effect on the complex dielectric constant. The values of relaxation time corresponding to this phenomena is also reported. Dielectric dispersion studies show that the solvent environment plays significant role in governing segmental motion of polymer chain in solution.

  15. Tuning the Morphology and Activity of Electrospun Polystyrene/UiO-66-NH2Metal-Organic Framework Composites to Enhance Chemical Warfare Agent Removal.

    Science.gov (United States)

    Peterson, Gregory W; Lu, Annie X; Epps, Thomas H

    2017-09-20

    This work investigates the processing-structure-activity relationships that ultimately facilitate the enhanced performance of UiO-66-NH 2 metal-organic frameworks (MOFs) in electrospun polystyrene (PS) fibers for chemical warfare agent detoxification. Key electrospinning processing parameters including solvent type (dimethylformamide [DMF]) vs DMF/tetrahydrofuran [THF]), PS weight fraction in solution, and MOF weight fraction relative to PS were varied to optimize MOF incorporation into the fibers and ultimately improve composite performance. It was found that composites spun from pure DMF generally resulted in MOF crystal deposition on the surface of the fibers, while composites spun from DMF/THF typically led to MOF crystal deposition within the fibers. For cases in which the MOF was incorporated on the periphery of the fibers, the composites generally demonstrated better gas uptake (e.g., nitrogen, chlorine) because of enhanced access to the MOF pores. Additionally, increasing both the polymer and MOF weight percentages in the electrospun solutions resulted in larger diameter fibers, with polymer concentration having a more pronounced effect on fiber size; however, these larger fibers were generally less efficient at gas separations. Overall, exploring the electrospinning parameter space resulted in composites that outperformed previously reported materials for the detoxification of the chemical warfare agent, soman. The data and strategies herein thus provide guiding principles applicable to the design of future systems for protection and separations as well as a wide range of environmental remediation applications.

  16. Co-pyrolysis of rice straw and polypropylene using fixed-bed pyrolyzer

    Science.gov (United States)

    Izzatie, N. I.; Basha, M. H.; Uemura, Y.; Mazlan, M. A.; Hashim, M. S. M.; Amin, N. A. M.; Hamid, M. F.

    2016-11-01

    The present work encompasses the impact of temperature (450, 500, 550, 600 °C) on the properties of pyrolysis oil and on other product yield for the co-pyrolysis of Polypropylene (PP) plastics and rice straw. Co-pyrolysis of PP plastic and rice straw were conducted in a fixed-bed drop type pyrolyzer under an inert condition to attain maximum oil yield. Physically, the pyrolysis oil is dark-brown in colour with free flowing and has a strong acrid smell. Copyrolysis between these typically obtained in maximum pyrolysis oil yields up to 69% by ratio 1:1 at a maximum temperature of 550 °C. From the maximum yield of pyrolysis oil, characterization of pyrolysis product and effect of biomass type of the composition were evaluated. Pyrolysis oil contains a high water content of 66.137 wt.%. Furfural, 2- methylnaphthalene, tetrahydrofuran (THF), toluene and acetaldehyde were the major organic compounds found in pyrolysis oil of rice straw mixed with PP. Bio-char collected from co-pyrolysis of rice straw mixed with PP plastic has high calorific value of 21.190 kJ/g and also carbon content with 59.02 wt.% and could contribute to high heating value. The non-condensable gases consist of hydrogen, carbon monoxide, and methane as the major gas components.

  17. Crosslinked polytriazole membranes for organophilic filtration

    KAUST Repository

    Chisca, Stefan

    2016-12-30

    We report the preparation of crosslinked membranes for organophilic filtration, by reacting a new polytriazole with free OH groups, using non-toxic poly (ethylene glycol) diglycidyl ether (PEGDE). The OH-functionalized polymer was obtained by converting the oxadiazole to triazole rings with high yield (98%). The maximum degree of crosslinking is achieved after 6 h of reaction. The crosslinked polytriazole membranes are stable in a wide range of organic solvents and show high creep recovery, indicating the robustness of crosslinked membranes. The influence of different casting solutions and different crosslinking time on the membrane morphology and membrane performance was investigated. The membranes performance was studied in dimethylformamide (DMF) and (tetrahydrofuran) THF. We achieved a permeance for THF of 49 L m−2 h−1 bar−1 for membranes with molecular weight cut off (MWCO) of 7 kg mol−1 and a permeance for THF of 17.5 L m−2 h−1 bar−1 for membranes with MWCO of 3 kg mol−1. Our data indicate that by using the new polytriazole is possible to adjust the pore dimensions of the membranes to have a MWCO, which covers ultra- and nanofiltration range.

  18. Changes of Lignin Molecular Structures in a Modification of Kraft Lignin Using Acid Catalyst

    Directory of Open Access Journals (Sweden)

    Sunghoon Kim

    2016-08-01

    Full Text Available The purpose of this study is to modify lignin for better blending with general purpose synthetic polymers. The possible advantages by using this modification would be cost reduction, better physical properties, and biodegradability. In this study, butyrolactone-modified lignin (BLL and tetrahydrofuran-modified lignin (THFL were used for aliphatic chain modification of lignin using an acid-catalyzed esterification method in order to mimic the relation of lignin-carbohydrate-complex (LCC and cellulose. The results of several analyses indicated that lignin was well modified. It was confirmed that the lignin was modified as expected and the reaction sites of the modification, as well as the reaction behaviors, were varied by the reagent types. The result of X-ray diffraction analysis (XRD analysis indicated that modified lignin/polymer blends increased the crystallinity due to their good compatibility. It can be confirmed that the type of alkyl chain and the miscibility gap between the alkyl chain-matrix affected the mechanical properties enormously in the fungi-degradable environment. From this study, a new method of lignin modification is proposed, and it is found that modified lignin retains the property of the substituted aliphatic chain well. This method could be a proper lignin modification method.

  19. Green synthesis of Co3O4/graphene nanocomposite as cathode for magnesium batteries

    Directory of Open Access Journals (Sweden)

    Kamar E. M.

    2017-10-01

    Full Text Available Ultrafine Co3O4 nanoparticles homogeneously attached to graphene sheets by sonochemical method have been demonstrated as a promising cathode material for magnesium batteries. X-ray diffraction (XRD, scanning electron microscopy (SEM, and energy dispersive spectroscopy (EDS have been employed to characterize the structural properties of this material. SEM analyses clearly confirmed that the Co3O4 nanoparticles have been uniformly coated on the entire surface of graphene sheets to form a compact composite. The Co3O4-graphene nanocomposite was employed as a cathode electrode in magnesium-ion batteries, and their electrochemical properties were briefly investigated. The graphene sheets can also effectively buffer the volume change in Co3O4 upon magnesium insertion/extraction, thus improving the cycling preformance of the composite electrode. It was revealed that the Co3O4-graphene composite can provide a small capacity of 16 mAh·g-1 using a new nonaqueous electrolyte that is tetrahydrofuran-free, which provides a new direction to explore cathode materials for Mg batteries.

  20. From carbon nanotubes and silicate layers to graphene platelets for polymer nanocomposites.

    Science.gov (United States)

    Zaman, Izzuddin; Kuan, Hsu-Chiang; Dai, Jingfei; Kawashima, Nobuyuki; Michelmore, Andrew; Sovi, Alex; Dong, Songyi; Luong, Lee; Ma, Jun

    2012-08-07

    In spite of extensive studies conducted on carbon nanotubes and silicate layers for their polymer-based nanocomposites, the rise of graphene now provides a more promising candidate due to its exceptionally high mechanical performance and electrical and thermal conductivities. The present study developed a facile approach to fabricate epoxy-graphene nanocomposites by thermally expanding a commercial product followed by ultrasonication and solution-compounding with epoxy, and investigated their morphologies, mechanical properties, electrical conductivity and thermal mechanical behaviour. Graphene platelets (GnPs) of 3.57 ± 0.50 nm in thickness were created after the expanded product was dispersed in tetrahydrofuran using 60 min ultrasonication. Since epoxy resins cured by various hardeners are widely used in industries, we chose two common hardeners: polyoxypropylene (J230) and 4,4'-diaminodiphenylsulfone (DDS). DDS-cured nanocomposites showed a better dispersion and exfoliation of GnPs, a higher improvement (573%) in fracture energy release rate and a lower percolation threshold (0.612 vol%) for electrical conductivity, because DDS contains benzene groups which create π-π interactions with GnPs promoting a higher degree of dispersion and exfoliation of GnPs during curing. This research pointed out a potential trend where GnPs would replace carbon nanotubes and silicate layers for many applications of polymer nanocomposites.

  1. Advanced liquefaction using coal swelling and catalyst dispersion techniques. Volume 2, appendices. Final technical report, October 1, 1991--September 30, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, C.W. [Auburn Univ., AL (United States); Chander, S. [Pennsylvania State Univ., College Park, PA (United States); Gutterman, C.

    1995-04-01

    Liquefaction experiments were undertaken using subbituminous Black Thunder mine coal to observe the effects of aqueous SO{sub 2} coal beneficiation and the introduction of various coal swelling solvents and catalyst precursors. Aqueous SO{sub 2} beneficiation of Black Thunder coal removed alkali metals and alkaline earth metals, increased the sulfur content and increased the catalytic liquefaction conversion to THF solubles compared to untreated Black Thunder coal. The liquefaction solvent had varying effects on coal conversion, depending upon the type of solvent added. The hydrogen donor solvent, dihydroanthracene, was most effective, while a coal-derived Wilsonville solvent promoted more coal conversion than did relatively inert 1-methylnaphthalene. Swelling of coal with hydrogen bonding solvents tetrahydrofuran (THF), isopropanol, and methanol, prior to reaction resulted in increased noncatalytic conversion of both untreated and SO{sub 2} treated Black Thunder coals, while dimethylsulfoxide (DMSO), which was absorbed more into the coal than any other swelling solvent, was detrimental to coal conversion. Swelling of SO{sub 2} treated coal before liquefaction resulted in the highest coal conversions; however, the untreated coal showed the most improvements in catalytic reactions when swelled in either THF, isopropanol, or methanol prior to liquefaction. The aprotic solvent DMSO was detrimental to coal conversion.

  2. Radiation effects in cold moderator materials: Experimental study of accumulation and release of chemical energy

    Science.gov (United States)

    Kulagin, E.; Kulikov, S.; Melikhov, V.; Shabalin, E.

    2004-01-01

    Study of radiation resistance of hydrogenous materials at low temperatures is a first priority task in the design of advanced cold neutron moderators. At temperatures 20-100 K the most essential radiation effects in solid hydrogenous substances are: Formation of radiolytic hydrogen. Accumulation of "frozen" radicals, which results in a rise of a self-sustaining reaction of their recombination followed with unexpected fast heating of the moderator. Formation of high-molecular, high-boiling products of radiolysis. Decrease of thermal conductivity. In the paper, the recently obtained results of the study of the accumulation of chemical energy and the conditions of its release performed with the URAM-2 cryogenic irradiation facility at the IBR-2 research reactor, are presented. Spontaneous releases of stored energy were detected in solid methane, water ice, hydrates of methane and tetrahydrofuran [Particles and Nuclei, Lett. 5 (2002) 82; Radiat. Phys. Chem. 67 (2003) 315] and in frozen mixtures of water ice with atomic hydrogen scavengers. A negligible amount of energy is accumulated in aromatic hydrocarbons which demonstrate no spontaneous self-heating under irradiation. All irradiation runs were performed at up to 20 MGy in the temperature range of 15-50 K.

  3. Synthesis and Insecticidal Activity of an Oxabicyclolactone and Novel Pyrethroids

    Directory of Open Access Journals (Sweden)

    Elson S. de Alvarenga

    2012-11-01

    Full Text Available Deltamethrin, a member of the pyrethroids, one of the safest classes of pesticides, is among some of the most popular and widely used insecticides in the World. Our objective was to synthesize an oxabicyclolactone 6 and five novel pyrethroids 8–12 from readily available furfural and D-mannitol, respectively, and evaluate their biological activity against four insect species of economic importance namely A. obtectus, S. zeamais, A. monuste orseis, and P. americana. A concise and novel synthesis of 6,6-dimethyl-3-oxabicyclo[3.1.0]hexan-2-one (6 from furfural is described. Photochemical addition of isopropyl alcohol to furan-2(5H-one afforded 4-(1'-hydroxy-1'-methylethyltetrahydro-furan-2-one (3. The alcohol 3 was directly converted into 4-(1'-bromo-1'-methylethyl-tetrahydrofuran-2-one (5 in 50% yield by reaction with PBr3 and SiO2. The final step was performed by cyclization of 5 with potassium tert-butoxide in 40% yield. The novel pyrethroids 8–12 were prepared from methyl (1S,3S-3-formyl-2,2-dimethylcyclopropane-1-carboxylate (7a by reaction with five different aromatic phosphorous ylides. Compounds 6–12 presented high insecticidal activity, with 6 and 11 being the most active. Compound 6 killed 90% of S. zeamais and 100% of all the other insects evaluated. Compound 11 killed 100% of all insects tested.

  4. Coordination Polymer Gels with Modular Nanomorphologies, Tunable Emissions, and Stimuli-Responsive Behavior Based on an Amphiphilic Tripodal Gelator.

    Science.gov (United States)

    Sutar, Papri; Maji, Tapas Kumar

    2017-08-21

    The recent upsurge in research on coordination polymer gels (CPGs) stems from their synthetic modularity, nanoscale processability, and versatile functionalities. Here we report self-assembly of an amphiphilic, tripodal low-molecular weight gelator (L) that consists of 4,4',4-[1,3,5-phenyl-tri(methoxy)]-tris-benzene core and 2,2':6',2″-terpyridyl termini, with different metal ions toward the formation of CPGs that show controllable nanomorphologies, tunable emission, and stimuli-responsive behaviors. L can also act as a selective chemosensor for Zn(II) with very low limit of detection (0.18 ppm) in aqueous medium. Coordination-driven self-assembly of L with Zn(II) in H2O/MeOH solvent mixture results in a coordination polymer hydrogel (ZnL) that exhibits sheet like morphology and charge-transfer emission. On the other hand, coordination of L with Tb(III) and Eu(III) in CHCl3/tetrahydrofuran solvent mixture results in green- and red-emissive CPGs, respectively, with nanotubular morphology. Moreover, precise stoichiometric control of L/Eu(III)/Tb(III) ratio leads to the formation of bimetallic CPGs that show emissions over a broad spectral range, including white-light-emission. We also explore the multistimuli responsive properties of the white-light-emitting CPG by exploiting the dynamics of Ln(III)-tpy coordination.

  5. Determination of polycyclic aromatic hydrocarbons in coffee brew using solid-phase extraction.

    Science.gov (United States)

    Houessou, Justin Koffi; Benac, Claire; Delteil, Corine; Camel, Valérie

    2005-02-23

    The presence of polycyclic aromatic hydrocarbons (PAHs) in coffee has been reported and is suspected to be due to the degradation of coffee compounds during the roasting step. Due to the high toxicity of these compounds, among which benzo[a]pyrene is known to be the most carcinogenic, their presence in the coffee, especially the coffee brew that is directly ingested by the consumer, is of prime importance. However, due to the low solubility of these compounds, their concentrations are expected to be rather low. As a consequence, reliable and sensitive analytical methods are required. The aim of this study was to develop a reliable and fast analytical procedure to determine these organic micropollutants in coffee brew samples. PAHs were retained on a 0.5 g polystyrene-divinylbenzene cartridge before being eluted by a mixture of methanol/tetrahydrofuran (10:90 v/v), concentrated, and directly analyzed by reversed-phase high-performance liquid chromatography coupled to a fluorescence detector. Application to the determination of PAHs in several coffee brew samples is also given, with mean estimated concentrations in the range of 0-100 ng L(-1) for suspected benzo[b]fluoranthene and benzo[a]pyrene, whereas no fluoranthene could be detected. Tentative identification was made on the basis of UV spectra. However, identification of the suspected traces of PAHs could not be achieved due to matrix effects, so that the presence of coeluting compounds may not be excluded.

  6. Simultaneous determination of MHD and DMD in dog plasma by high-performance liquid chromatography with fluorescence detection and its application to pharmacokinetic studies.

    Science.gov (United States)

    Li, Xiaoyu; Wang, Guangji; Xie, Haitang; Wang, Rui; Xu, Meijuan; Wang, Wei; Tao, Jining; Sun, Jianguo

    2006-02-01

    A rapid, reproducible high-performance liquid chromatographic (HPLC) method with fluorescence detection for the simultaneous determination of 3(or 8)-(1-methoxyethyl)-8(or 3)-(1-hydroxyethyl)-deuteroporphyrin IX (MHD) and 3,8-di-(1-methoxyethyl)-deuteroporphyrin IX (DMD) in dog plasma was described. Fluorescein was used as an internal standard. A simple extraction step with ethyl acetate was performed before chromatography on a Diamonsil C18 column (5 microm, 4.6 mm x 150 mm). The chromatography used 0.02 mol L(-1) sodium acetate/tetrahydrofuran (66:34 v/v). The analytical curve was linear over the concentration range 0.025-2.5 microg mL(-1). For a 100 microL dog plasma sample, the limit of determination for both MHD and DMD was 0.025 microg mL(-1). The recoveries of MHD and DMD were more than 76% and 89%, respectively. The intra-assay (within-run) and interassay (between-run) coefficients of variation (precisions) for MHD and DMD were less than 15%. This method was found to be suitable for the analysis of biosamples and was successfully applied to pharmacokinetic studies of Deuxemether in dogs.

  7. Solution-processable phosphorescence based on iridium-cored small molecules with the trifluoromethyl group

    Science.gov (United States)

    Zhang, Wenguan; He, Zhiqun; Wang, Yongsheng; Zhao, Shengmin

    2015-04-01

    A novel cyclometallated ligand 2-(4-(2‧-ethylhexyloxy)phenyl)-5-trifluoromethyl-pyridine (EHO-5CF3-ppy) was synthesized, and two solution-processable iridium complexes bis[2-(4-(2‧-ethylhexyloxy)phenyl)-5-trifluoromethylpyridinto-C3, N] iridium (acetylacetonate) (EHO-5CF3-ppy)2Ir(acac) (5) and bis[2-(4-(2‧-ethylhexyl-oxy)phenyl)-5-trifluoromethylpyridinto-C3, N] iridium (2-picolinic acid) (EHO-5CF3-ppy)2Ir(pic) (6) were afforded. Trifluoromethyl and dendritic ethylhexyloxy group were incorporated into iridium ligands to tune luminescent color, to reduce luminescence quenching and to improve the solution-processable property. Photoluminescent spectra of 5 and 6 in tetrahydrofuran peaked at around 540 and 523 nm. Electrophosphorescent devices were fabricated using 5 and 6 as dopant emitters (2%), which exhibited electroluminescent (EL) peaks at 536 and 524 nm, and current efficiencies of 10.4 and 16.7 cd/A, respectively. With the concentration of iridium complexes increasing to 8%, the main EL peak showed a 4 nm of red shift and a distinct shoulder peak occurred at 583 nm for 5 or 560 nm for 6, respectively. Maximum external quantum efficiencies of the devices at the concentration of 2% and 8% were 2.8% and 4.2% for 5, 4.7% and 4.8% for 6. These indicated that 5 and 6 were efficient solution-processable emitters.

  8. Method for analysis of polar volatile trace components in aqueous samples by gas chromatography.

    Science.gov (United States)

    Pettersson, Johan; Roeraade, Johan

    2005-05-15

    A new method has been developed for direct analysis of volatile polar trace compounds in aqueous samples by gas chromatography. Water samples are injected onto a short packed precolumn containing anhydrous lithium chloride. A capillary column is coupled in series with the prefractionation column for final separation of the analytes. The enrichment principle of the salt precolumn is reverse to the principles employed in conventional methods such as SPE or SPME in which a sorbent or adsorbent is utilized to trap or concentrate the analytes. Such methods are not efficient for highly polar compounds. In the LiCl precolumn concept, the water matrix is strongly retained on the hygroscopic salt, whereas polar as well as nonpolar volatile organic compounds show very low retention and are eluted ahead of the water. After transfer of the analytes to the capillary column, the retained bulk water is removed by backflushing the precolumn at elevated temperature. For direct injections of 120 microL of aqueous samples, the combined time for injection and preseparation is only 3.5 min. With this procedure, direct repetitive automated analyses of highly volatile polar compounds such as methanol or tetrahydrofuran can be performed, and a limit of quantification in the low parts-per-billion region utilizing a flame ionization detector is demonstrated.

  9. Solvent effects on polymer sorting of carbon nanotubes with applications in printed electronics.

    Science.gov (United States)

    Wang, Huiliang; Hsieh, Bing; Jiménez-Osés, Gonzalo; Liu, Peng; Tassone, Christopher J; Diao, Ying; Lei, Ting; Houk, Kendall N; Bao, Zhenan

    2015-01-07

    Regioregular poly(3-alkylthiophene) (P3AT) polymers have been previously reported for the selective, high-yield dispersion of semiconducting single-walled carbon nanotubes (SWCNTs) in toluene. Here, five alternative solvents are investigated, namely, tetrahydrofuran, decalin, tetralin, m-xylene, and o-xylene, for the dispersion of SWCNTs by poly(3-dodecylthiophene) P3DDT. The dispersion yield could be increased to over 40% using decalin or o-xylene as the solvents while maintaining high selectivity towards semiconducting SWCNTs. Molecular dynamics (MD) simulations in explicit solvents are used to explain the improved sorting yield. In addition, a general mechanism is proposed to explain the selective dispersion of semiconducting SWCNTs by conjugated polymers. The possibility to perform selective sorting of semiconducting SWCNTs using various solvents provides a greater diversity of semiconducting SWCNT ink properties, such as boiling point, viscosity, and surface tension as well as toxicity. The efficacy of these new semiconducting SWCNT inks is demonstrated by using the high boiling point and high viscosity solvent tetralin for inkjet-printed transistors, where solvent properties are more compatible with the inkjet printing head and improved droplet formation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Selective conversion of cellulose in corncob residue to levulinic acid in an aluminum trichloride-sodium chloride system.

    Science.gov (United States)

    Li, Jianmei; Jiang, Zhicheng; Hu, Libin; Hu, Changwei

    2014-09-01

    Increased energy consumption and environmental concerns have driven efforts to produce chemicals from renewable biomass with high selectivity. Here, the selective conversion of cellulose in corncob residue, a process waste from the production of xylose, to levulinic acid was carried out using AlCl3 as catalyst and NaCl as promoter by a hydrothermal method at relatively low temperature. A levulinic acid yield of 46.8 mol% was obtained, and the total selectivity to levulinic acid with formic acid was beyond 90%. NaCl selectively promoted the dissolution of cellulose from corncob residue, and significantly improved the yield and selectivity to levulinic acid by inhibiting lactic acid formation in the subsequent dehydration process. Owing to the salt effect of NaCl, the obtained levulinic acid could be efficiently extracted to tetrahydrofuran from aqueous solution. The aqueous solution with AlCl3 and NaCl could be recycled 4 times. Because of the limited conversion of lignin, this process allows for the production of levulinic acid with high selectivity directly from corncob residue in a simple separation process. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Direct Observation of THF Hydrate Formation in Porous Microstructure Using Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    Di Liu

    2012-04-01

    Full Text Available The porous microstructure of hydrates governs the mechanical strength of the hydrate-bearing sediment. To investigate the growth law and microstructure of hydrates in porous media, the growth process of tetrahydrofuran (THF hydrate under different concentration of THF solution is directly observed using Magnetic Resonance Imaging (MRI. The images show that the THF hydrate grows as different models under different concentration of THF solution (19%, 11.4% and 5.7% by weight at 1 °C. When the concentration is 19% (stoichiometric molar ratio of THF/H2O = 1:17, the THF hydrate grows as cementing model. However, with the decreasing concentration of THF, the growth model transfers from cementing model to floating model. The results show that the growth of the THF hydrate was influenced by the dissolved quantity of THF in the water. The extension of the observed behavior to methane hydrate could have implications in understanding their role in seafloor and permafrost stability.

  12. Seed oil triglyceride profiling of thirty-two hybrid grape varieties.

    Science.gov (United States)

    De Marchi, Fabiola; Seraglia, Roberta; Molin, Laura; Traldi, Pietro; De Rosso, Mirko; Panighel, Annarita; Dalla Vedova, Antonio; Gardiman, Massimo; Giust, Mirella; Flamini, Riccardo

    2012-09-01

    Triglyceride profile of seed oil samples from 32 hybrid grape varieties not studied before was investigated. A new method for the analysis of triacylglycerols (TAGs) has been developed based on the direct infusion in the electrospray ionization (ESI) source and employing tetrahydrofuran/methanol/water (85:10:5 v|v|v) as solvent; the formation of [M + Na](+) ions in high yield has been observed. TAGs were identified by ESI-tandem mass spectrometry analysis, and the matrix-assisted-laser-desorption-ionization and time-of-flight profile of samples was determined. Six were the principal TAGs identified in seed oil: trilinolein (LLL) was the most abundant (43%), followed by dilinoleoyl-oleoylglycerol (LOL, 23%), and dilinoleoyl-palmitoylglycerol (LPL, 15%). Compounds present in lower concentration were LSL and LOO (11%), LOP (6%), and LSP (2%). Compared with seed oils produced from V. Vinifera grapes, some significant differences in the relative abundances of TAGs were found, in particular hybrid grape seed oils showed higher LOL and lower LPL content, respectively. Among the samples studied, a particularly high content of LLL (rich in unsaturated fatty acids) was found in seed oils from two red varieties. Copyright © 2012 John Wiley & Sons, Ltd.

  13. Benzocoumarin-Styryl Hybrids: Aggregation and Viscosity Induced Emission Enhancement.

    Science.gov (United States)

    Warde, Umesh; Sekar, Nagaiyan

    2017-09-01

    Two benzo[h]chromen-3-yl)ethylidene) malononitrile styryl hybrid dyes are synthesized and characterized by NMR and elemental analysis. One is based on nitrogen donor and other on oxygen (3b and 3b respectively). Dyes are low emissive in the solution but dramatically showed increase in emission intensity in aggregates form in the THF (tetrahydrofuran) /water system. Dyes are also sensitive to viscosity and showed increased emission intensity in the DCM:PEG 400 system and DMF:PEG 400 system respectively. Dyes 3a and 3b showed higher viscosity sensitivity constant (0.67 and 0.39 respectively) in DMF:PEG 400 system compared to DCM:PEG 400 (0.47 and 0.21 respectively) system which is contrary to the traditional concept of FMRs. Results shows that lowering of twisted intramolecular charge transfer (TICT) and increase in intramolecular charge transfer (ICT) in the excited state could be the reason for such behavior in the aggregate and highly viscous state. This study may provide the new insights into the field of AIEE and FMR research of such hybrid molecules.

  14. The synthesis and properties of linear A-π-D-π-A type organic small molecule containing diketopyrrolopyrrole terminal units

    Science.gov (United States)

    Zhang, Shanshan; Niu, Qingfen; Sun, Tao; Li, Yang; Li, Tianduo; Liu, Haixia

    2017-08-01

    A novel linear A-π-D-π-A-type organic small molecule Ph2(PDPP)2 consisting diketopyrrolopyrrole (DPP) as acceptor unit, biphenylene as donor unit and acetylene unit as π-linkage has been successfully designed and synthesized. Its corresponding thermal, photophysical and electrochemical properties as well as the photoinduced charge-separation process were investigated. Ph2(PDPP)2 exhibits high thermal stability and it can be soluble in common organic solvents such as chloroform and tetrahydrofuran. The photophysical properties show that DPP2Ph2 harvests sunlight over the entire visible spectrum range in the thin-film state (300-800 nm). DPP2Ph2 has lower band gaps and appropriate energy levels to satisfy the requirement of solution-processable organic solar cells. The efficient photoinduced charge separation process was clearly observed between DPP2Ph2 with PC61BM and the Ksv value was found to be as high as 2.13 × 104 M- 1. Therefore, these excellent properties demonstrate that the designed A-π-D-π-A-type small molecule Ph2(PDPP)2 is the prospective candidate as donor material for organic photovoltaic material.

  15. Magnetically separable and recyclable Fe3O4-polydopamine hybrid hollow microsphere for highly efficient peroxidase mimetic catalysts.

    Science.gov (United States)

    Liu, Shujun; Fu, Jianwei; Wang, Minghuan; Yan, Ya; Xin, Qianqian; Cai, Lu; Xu, Qun

    2016-05-01

    Magnetic Fe3O4-polydopamine (PDA) hybrid hollow microspheres, in which Fe3O4 nanoparticles were firmly incorporated in the cross-linked PDA shell, have been prepared through the formation of core/shell PS/Fe3O4-PDA composites based on template-induced covalent assembly method, followed by core removal in a tetrahydrofuran solution. The morphology, composition, thermal property and magnetic property of the magnetic hybrid hollow microspheres were characterized by SEM, TEM, FT-IR, XRD, TGA, and vibrating sample magnetometer, respectively. Results revealed that the magnetic hybrid hollow microspheres had about 380 nm of inner diameter and about 30 nm of shell thickness, and 13.6 emu g(-1) of magnetization saturation. More importantly, the Fe3O4-PDA hybrid hollow microspheres exhibited intrinsic peroxidase-like activity, as they could quickly catalyze the oxidation of typical substrates 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide. Compared with PDA/Fe3O4 composites where Fe3O4 nanoparticles were loaded on the surface of PDA microspheres, the stability of Fe3O4-PDA hybrid hollow microspheres was greatly improved. As-prepared magnetic hollow microspheres might open up a new application field in biodetection, biocatalysis, and environmental monitoring. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Micro/nano-structured polypyrrole surfaces on oxidizable metals as smart electroswitchable coatings.

    Science.gov (United States)

    Santos, Luis; Martin, Pascal; Ghilane, Jalal; Lacaze, Pierre Camille; Lacroix, Jean-Christophe

    2013-10-23

    Polypyrrole (PPy) films were electrodeposited from a pyrrole/sodium salicylate solution in water, through two-dimensional (2-D) polystyrene (PS) templates self-assembled on various oxidizable metals, after which the template was removed by dissolution in tetrahydrofuran (THF). The resulting PPy films were analyzed by scanning electron microscopy and atomic force microscopy. Two-dimensional PPy honeycomb structures are obtained on copper or mild steel by using PS spheres of various sizes. The morphology of these structures was controlled electrochemically, as an increase in the polymerization charge does not disturb the PPy honeycomb arrangement, leading instead to the formation of deeper pores accompanied by a change in their diameter. The hydrophobicity of the reduced micro-structured PPy surface is much greater than that of a bulk PPy film generated on the same metal. Reversible electro-switching of the wettability was obtained with marked variation of the apparent contact angle upon PPy oxido-reduction, and an important effect of film micro-structuration upon the wettability range.

  17. PCL/MWCNT Nanocomposites as Nanosensors

    Science.gov (United States)

    Grozdanov, Anita; Buzarovska, Alexandra; Avella, Maurizio; Errico, Maria E.; Gentile, Gennaro

    Due to the unique electronic, metallic and structural properties of carbon nanotubes (CNTs) as compared to other materials, researchers focused on utilizing these characteristics for engineering applications such as actuators, hydrogen storage materials, chemical sensors and nanoelectronic devices. Many papers have been published utilizing CNTs as the sensing material in pressure, flow, thermal, gas, optical, mass, strain, stress, chemical and biological sensors. Amongst many of their superior electro-mechanical properties, the piezoresistive effect in CNTs is attractive for designing strain sensors. When CNTs are subjected to a mechanical strain, a change in their chirality leads to modulation of the conductance. In this paper, a novel carbon nanotube/biopolymer nanocomposite was used to develop a piezoresistive strain nano bio-sensor. A biocompatible polymer matrix has been used to provide good interfacial bonding between the carbon nanotubes. Multi-walled carbon nanotubes (MWCNT, diameter d = 30-50 nm, purity >95%) have been used for the preparation of polycaprolactone (PCL)-based nanocomposites (PCL/MWCNT). The nanocomposites were prepared by mixing the MWCNTs and PCL in a tetrahydrofuran solution for 24 h. Characterization of the PCL/MWCNTs nanocomposite films was performed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR) and scanning electron microscopy (SEM), as well as by mechanical and electrical measurements.

  18. Quinine-Based Zwitterionic Chiral Stationary Phase as a Complementary Tool for Peptide Analysis: Mobile Phase Effects on Enantio- and Stereoselectivity of Underivatized Oligopeptides.

    Science.gov (United States)

    Ianni, Federica; Sardella, Roccaldo; Carotti, Andrea; Natalini, Benedetto; Lindner, Wolfgang; Lämmerhofer, Michael

    2016-01-01

    Peptide stereoisomer analysis is of importance for quality control of therapeutic peptides, the analysis of stereochemical integrity of bioactive peptides in food, and the elucidation of the stereochemistry of peptides from a natural chiral pool which often contains one or more D-amino acid residues. In this work, a series of model peptide stereoisomers (enantiomers and diastereomers) were analyzed on a zwitterionic ion-exchanger chiral stationary phase (Chiralpak ZWIX(+) 5 µm), in order to investigate the retention and separation performance for such compounds on this chiral stationary phase and elucidate its utility for this purpose. The goal of the study focused on 1) investigations of the effects of the sample matrix used to dissolve the peptide samples; 2) optimization of the mobile phase (enabling deriving information on factors of relevance for retention and separation); and 3) derivation of structure-selectivity relationships. It turned out that small di- and tripeptides can be well resolved under optimized conditions, typically with resolutions larger than 1.5. The optimized mobile phase often consisted of methanol-tetrahydrofuran-water (49:49:2; v/v/v) with 25 mM formic acid and 12.5 mM diethylamine. This work proposes some guidance on which mobile phases can be most efficiently used for peptide stereoisomer separations on Chiralpak ZWIX. Chirality 28:5-16, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  19. Chiral liquid-crystalline polyacrylates from (S-(--2-methyl-1-butanol. Synthesis, mesomorphic properties and light scattering

    Directory of Open Access Journals (Sweden)

    Merlo Aloir A.

    2001-01-01

    Full Text Available The synthesis and mesomorphic behavior of two chiral side chain liquid crystalline polyacrylates from (S-(--2-methyl-1-butanol are described. These new polyacrylates show a dependence of the phase transition temperatures on both, molecular weight and spacer length. The polyacrylate with four methylene units in the spacer exhibits a chiral nematic phase whereas the polyacrylate with a spacer containing eleven methylene units presents a smectic phase. In addition, the chiral nematic phase appears for low molecular weight and smectic phase for high molecular weight polyacrylates. Light scattering experiments were performed in dilute solutions of the polyacrylate containing eleven methylene units in tetrahydrofuran and dichloromethane. Values for weight averaged molecular weight, radius of gyration and second virial coefficient were determined by static light scattering whereas the diffusion coefficient and the hydrodynamic radius of the chains were obtained by photon correlation spectroscopy. A comparison between both techniques indicates that the chain behavior can be taken as typical for a polydisperse linear chain in a good solvent.

  20. 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.

  1. Phosphorus-phosphorus coupling in a diphosphine with a ten bond P...P separation.

    Science.gov (United States)

    Kuhn, P; Jeunesse, C; Matt, D; Harrowfield, J; Ricard, L

    2006-07-28

    The large, unsymmetrical diphosphine 5,11,17,23-tetra-tert-butyl-25,26-bis(diphenylphosphinomethoxy)-27(or 28)-benzoyloxy-28(or 27)-hydroxycalix[4]arene, in which the phosphorus atoms are separated by ten bonds, was prepared by monobenzoylation of 5,11,17,23-tetra-tert-butyl-25,26-bis(diphenylphosphinoylmethoxy)-27,28-bis(hydroxy)calix[4]arene, followed by reduction with phenyl silane. Its molecular structure has been determined by X-ray crystallography. In the solid state, the phosphorus atoms are separated by 5.333(1) A. NMR investigations reveal an unexpected "through-space"J(PP') coupling constant of 8.0 Hz and also show that, in solution, the calixarene is conformationally mobile, the phenoxy ring flipping rapidly through the calixarene annulus. The spatial proximity of the two phosphorus atoms was further demonstrated by the ease of obtaining the cis-chelate complex [Pd(eta3-C3H4Me)(THF)2]BF4 (THF = tetrahydrofuran).

  2. Stability and Unimolecular Reactivity of Palladate(II) Complexes [Ln PdR3 ](-) (L=Phosphine, R=Organyl, n=0 and 1).

    Science.gov (United States)

    Kolter, Marlene; Koszinowski, Konrad

    2016-10-24

    The reduction of Pd(II) precatalysts to catalytically active Pd(0) species is a key step in many palladium-mediated cross-coupling reactions. Besides phosphines, the stoichiometrically used organometallic reagents can afford this reduction, but do so in a poorly understood way. To elucidate the mechanism of this reaction, we have treated solutions of Pd(OAc)2 and a phosphine ligand L in tetrahydrofuran with RMgCl (R=Ph, Bn, Bu) as well as other organometallic reagents. Analysis of these model systems by electrospray- ionization mass spectrometry found palladate(II) complexes [Ln PdR3 ](-) (n=0 and 1), thus pointing to the occurrence of transmetallation reactions. Upon gas-phase fragmentation, the [Ln PdR3 ](-) anions preferentially underwent a reductive elimination to yield Pd(0) species. The sequence of the transmetallation and reductive elimination, thus, constitutes a feasible mechanism for the reduction of the Pd(OAc)2 precatalyst. Other species of interest observed include the Pd(IV) complex [PdBn5 ](-) , which did not fragment via a reductive elimination but lost BnH instead. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Funcionamiento de una membrana de zeolita 4-A comercial en la deshidratación de disolventes industriales mediante pervaporación

    Directory of Open Access Journals (Sweden)

    Urtiaga, A. M.

    2004-02-01

    Full Text Available The performance of a commercial zeolite NaA pervaporation membrane supplied by Smart Chem., U.K. was studied with respect to the dehydration of industrial mixtures of tetrahydrofurane/water (CH2O≤7.9 wt.% and acetone/water (CH2O≤3.25 wt.%. The influence of water concentration and temperature in the range 40 ºC - 65 ºC on fluxes and selectivities was described. The stability of the membrane in consecutive operation cycles is also reported.

    En este trabajo se estudia el comportamiento de una membrana comercial de pervaporación con una capa activa de zeolita NaA (Smart Chem., Reino Unido aplicada a la separación de dos mezclas de origen industrial: tetrahidrofurano/agua con un contenido inicial de agua de 7,9% en peso y acetona/agua con un contenido inicial de agua de 3,25% en peso. Se ha caracterizado el flujo de agua y la selectividad de la separación, estudiándose la influencia de la composición y de la temperatura, en el rango 40 ºC - 65 ºC sobre ambos factores. Asimismo, se ha estudiado la estabilidad de la membrana en ciclos consecutivos de operación.

  4. Effect of gamma irradiation on the mechanical properties of PVC/ZnO polymer nanocomposite

    Directory of Open Access Journals (Sweden)

    Abdullah Al Naim

    2017-07-01

    Full Text Available Polyvinyl Chloride (PVC based nanocomposite with different weight ratios of Zinc oxide (ZnO nanoparticles is prepared by using a gel-like technique. The weight-ratio of ZnO nanoparticles, in a range of 2.5–10 wt%, is used to prepare nanocomposites' in the tetrahydrofuran (THF solvent. The as-prepared samples are exposed to gamma (γ radiation at different doses in a range of 5–40 kGy. The mechanical properties of irradiated samples are compared to that of unirradiated samples. For unirradiated samples, the elasticity is found to increase with the addition of ZnO nanoparticles. However, the plastic region of the stress-strain curve gets slightly affected on increasing the concentration of ZnO. Additionally, the elastic modulus is noticed to drop exponentially with ZnO concentration. For pure PVC, a slight dependence of stress-strain curves on the gamma irradiation doses has also been detected. Further, the gamma irradiation dose results in a detectable decrease of elastic modulus for pure and low weight-ratio ZnO nanoparticles. However, the irradiation dose does not have any effect on the elastic modulus for the 10 wt %, which is the highest weight ratio used in this study.

  5. Dispersive liquid-liquid microextraction combined with non-aqueous capillary electrophoresis for the determination of imazalil, prochloraz and thiabendazole in apples, cherry tomatoes and grape juice.

    Science.gov (United States)

    Xu, Lina; Luan, Feng; Liu, Huitao; Gao, Yuan

    2015-03-15

    Fruit and vegetables are frequently treated with fungicides to reduce possible spoilage. As a result, fungicide residues may be accumulated in derived products. This important group of chemical compounds has been heavily regulated because of their potential toxicity. Therefore, a simple and rapid method to determine fungicides is desired. A simple non-aqueous capillary electrophoresis (NACE) method based on dispersive liquid-liquid microextraction (DLLME) has been proposed for the determination of imazalil, prochloraz and thiabendazole fungicides in fruits and juice samples. Separation buffer consisted of a methanol-acetonitrile mixture (35:65, v/v) containing 30 mmol L⁻¹ ammonium chloride and 0.5% phosphoric acid. The optimum DLLME conditions were 80 µL trichloromethane as extraction solvent, 0.5 mL tetrahydrofuran as disperser solvent, sample solution pH at 6.0, 5% (w/v) NaCl and 10 s extraction time. Recoveries obtained for various samples ranged from 72% to 102%, with relative standard deviation lower than 6.4%. The limits of detection ranged from 0.47 to 0.72 µg kg⁻¹. The proposed method takes the advantages of DLLME and NACE. It is rapid, accurate, sensitive and reproducible for the determination of imazalil, prochloraz and thiabendazole in fruit samples. © 2014 Society of Chemical Industry.

  6. TLC determination of flavonoids from different cultivars of Allium cepa and Allium ascalonicum.

    Science.gov (United States)

    Pobłocka-Olech, Loretta; Głód, Daniel; Żebrowska, Maria E; Sznitowska, Małgorzata; Krauze-Baranowska, Miroslawa

    2016-12-01

    This study comprises the optimization and validation of a new TLC method for determination of flavonols in the bulbs of seven cultivars of onions and shallots. Separation was performed on RP-18 plates with the solvent mixture tetrahydrofuran/water/formic acid (40+60+6, V/V/V) as a mobile phase. The method was evaluated for precision, linearity, LOD, LOQ, accuracy and robustness. Chromatographic analysis of the extracts revealed the presence of three main flavonols, quercetin, quercetin-4'-O-glucoside and quercetin-3,4'-O-diglucoside in the majority of analyzed cultivars. The content of flavonols in the analyzed extracts of onion bulbs varied from 123 ('Exihibition') to 1079 mg kg-1 fresh mass (fm) ('Hybing') in edible parts, and from 1727 ('Hyline') to 28949 mg kg-1 fm ('Red Baron') in outer scales. The bulbs of two shallot cultivars contained 209 ('Ambition') and 523 mg kg-1 fm ('Matador') of flavonols in edible parts and 5426 and 8916 mg kg-1 fm in outer scales, respectively.

  7. Support vector regression and least squares support vector regression for hormetic dose-response curves fitting.

    Science.gov (United States)

    Qin, Li-Tang; Liu, Shu-Shen; Liu, Hai-Ling; Zhang, Yong-Hong

    2010-01-01

    Accurate description of hormetic dose-response curves (DRC) is a key step for the determination of the efficacy and hazards of the pollutants with the hormetic phenomenon. This study tries to use support vector regression (SVR) and least squares support vector regression (LS-SVR) to address the problem of curve fitting existing in hormesis. The SVR and LS-SVR, which are entirely different from the non-linear fitting methods used to describe hormetic effects based on large sample, are at present only optimum methods based on small sample often encountered in the experimental toxicology. The tuning parameters (C and p1 for SVR, gam and sig2 for LS-SVR) determining SVR and LS-SVR models were obtained by both the internal and external validation of the models. The internal validation was performed by using leave-one-out (LOO) cross-validation and the external validation was performed by splitting the whole data set (12 data points) into the same size (six data points) of training set and test set. The results show that SVR and LS-SVR can accurately describe not only for the hermetic J-shaped DRC of seven water-soluble organic solvents consisting of acetonitrile, methanol, ethanol, acetone, ether, tetrahydrofuran, and isopropanol, but also for the classical sigmoid DRC of six pesticides including simetryn, prometon, bromacil, velpar, diquat-dibromide monohydrate, and dichlorvos. Copyright 2009 Elsevier Ltd. All rights reserved.

  8. Third order nonlinear optical properties of stacked bacteriochlorophylls in bacterial photosynthetic light-harvesting proteins

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L.X.; Laible, P.D. [Argonne National Lab., IL (United States). Chemistry Div.; Spano, F.C.; Manas, E.S. [Temple Univ., Philadelphia, PA (United States). Dept. of Chemistry

    1997-09-01

    Enhancement of the nonresonant second order molecular hyperpolarizabilities {gamma} were observed in stacked macrocyclic molecular systems, previously in a {micro}-oxo silicon phthalocyanine (SiPcO) monomer, dimer and trimer series, and now in bacteriochlorophyll a (BChla) arrays of light harvesting (LH) proteins. Compared to monomeric BChla in a tetrahydrofuran (THF) solution, the <{gamma}> for each macrocycle was enhanced in naturally occurring stacked macrocyclic molecular systems in the bacterial photosynthetic LH proteins where BChla`s are arranged in tilted face-to-face arrays. In addition, the {gamma} enhancement is more significant in B875 of LH1 than in B850 in LH2. Theoretical modeling of the nonresonant {gamma} enhancement using simplified molecular orbitals for model SiPcO indicated that the energy level of the two photon state is crucial to the {gamma} enhancement when a two photon process is involved, whereas the charge transfer between the monomers is largely responsible when one photon near resonant process is involved. The calculated results can be extended to {gamma} enhancement in B875 and B850 arrays, suggesting that BChla in B875 are more strongly coupled than in B850. In addition, a 50--160 fold increase in <{gamma}> for the S{sub 1} excited state of relative to S{sub 0} of bacteriochlorophyll in vivo was observed which provides an alternative method for probing excited state dynamics and a potential application for molecular switching.

  9. Structure and Conductivity of Semiconducting Polymer Hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Huber, Rachel C.; Ferreira, Amy S.; Aguirre, Jordan C.; Kilbride, Daniel; Toso, Daniel B.; Mayoral, Kenny; Zhou, Z. Hong; Kopidakis, Nikos; Rubin, Yves; Schwartz, Benjamin J.; Mason, Thomas G.; Tolbert, Sarah H.

    2016-07-07

    Poly(fluorene-alt-thiophene) (PFT) is a conjugated polyelectrolyte that self-assembles into rod-like micelles in water, with the conjugated polymer backbone running along the length of the micelle. At modest concentrations (-10 mg/mL in aqueous solutions), PFT forms hydrogels, and this work focuses on understanding the structure and intermolecular interactions in those gel networks. The network structure can be directly visualized using cryo electron microscopy. Oscillatory rheology studies further tell us about connectivity within the gel network, and the data are consistent with a picture where polymer chains bridge between micelles to hold the network together. Addition of tetrahydrofuran (THF) to the gels breaks those connections, but once the THF is removed, the gel becomes stronger than it was before, presumably due to the creation of a more interconnected nanoscale architecture. Small polymer oligomers can also passivate the bridging polymer chains, breaking connections between micelles and dramatically weakening the hydrogel network. Fits to solution-phase small-angle X-ray scattering data using a Dammin bead model support the hypothesis of a bridging connection between PFT micelles, even in dilute aqueous solutions. Finally, time-resolved microwave conductivity measurements on dried samples show an increase in carrier mobility after THF annealing of the PFT gel, likely due to increased connectivity within the polymer network.

  10. Kinetics of Levoglucosenone Isomerization.

    Science.gov (United States)

    Krishna, Siddarth H; Walker, Theodore W; Dumesic, James A; Huber, George W

    2017-01-10

    We studied the acid-catalyzed isomerization of levoglucosenone (LGO) to 5-hydroxymethylfurfural (HMF) and developed a reaction kinetics model that describes the experimental data across a range of conditions (100-150 °C, 50-100 mm H2 SO4 , 50-150 mm LGO). LGO and its hydrated derivative exist in equilibrium under these reaction conditions. Thermal and catalytic degradation of HMF are the major sources of carbon loss. Within the range of conditions studied, higher temperatures and shorter reaction times favor the production of HMF. The yields of HMF and levulinic acid decrease monotonically as tetrahydrofuran is added to the aqueous solvent system, indicating that water plays a role in the LGO isomerization reaction. Initial-rate analyses show that HMF is produced solely from LGO rather than from the hydrated derivative of LGO. The results of this study are consistent with a mechanism for LGO isomerization that proceeds through hydration of the anhydro bridge, followed by ring rearrangement analogous to the isomerization of glucose to fructose. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. SYNTHESIS OF TETRA-p-PROPENYLTETRAESTERCALIX[4]ARENE AND TETRA-p-PROPENYLTETRACARBOXYLICACIDCALIX[4]ARENE FROM p-t-BUTYLPHENOL

    Directory of Open Access Journals (Sweden)

    Triana Kusumaningsih

    2010-06-01

    Full Text Available A research has been conducted to synthesize tetra-p-propenyltetraestercalix[4]arene and tetra-p-propenyltetracarboxylicacidcalix[4] arene using p-t-butylphenol as a starting material. The synthesis was carried out in following stages, i.e (1 synthesis of p-t-butylcalix[4]arene from p-t-butylphenol, (2 debutylation of p-t-butylcalix[4]arene, (3 tetraallilation of 25,26,27,28-tetrahydroxycalix[4]arene with NaH and allilbromida in dry tetrahydrofuran, (4 Claissen rearrangement of 25,26,27,28-tetrapropenyloxycalix[4]arene, (5 esterification of tetra-p-propenyltetrahydroxycalix[4]arene, (6 hydrolisis of tetra-p-propenyltetraestercalix[4]arene. The all structures of products were observed by means of melting point, FTIR, and 1H-NMR spectrometers. Tetra-p-propenyltetraestercalix[4]arene compound was obtained as yellow liquid product in 55.08% yield. Tetra-p-propenyltetracarboxylicacidcalix[4]arene compound was obtained as white solid product with the melting point 135-137 °C at decomposed and in 70.05% yield.   Keywords: calix[4]arene, Claissen rearrangement, esterification, hydrolisis

  12. An Efficient Synthesis Strategy for Metal-Organic Frameworks: Dry-Gel Synthesis of MOF-74 Framework with High Yield and Improved Performance.

    Science.gov (United States)

    Das, Atanu Kumar; Vemuri, Rama Sesha; Kutnyakov, Igor; McGrail, B Peter; Motkuri, Radha Kishan

    2016-06-16

    Vapor-assisted dry-gel synthesis of the metal-organic framework-74 (MOF-74) structure, specifically Ni-MOF-74 produced from synthetic precursors using an organic-water hybrid solvent system, showed a very high yield (>90% with respect to 2,5-dihydroxyterepthalic acid) and enhanced performance. The Ni-MOF-74 obtained showed improved sorption characteristics towards CO2 and the refrigerant fluorocarbon dichlorodifluoromethane. Unlike conventional synthesis, which takes 72 hours using the tetrahydrofuran-water system, this kinetic study showed that Ni-MOF-74 forms within 12 hours under dry-gel conditions with similar performance characteristics, and exhibits its best performance characteristics even after 24 hours of heating. In the dry-gel conversion method, the physical separation of the solvent and precursor mixture allows for recycling of the solvent. We demonstrated efficient solvent recycling (up to three times) that resulted in significant cost benefits. The scaled-up manufacturing cost of Ni-MOF-74 synthesized via our dry-gel method is 45% of conventional synthesis cost. Thus, for bulk production of the MOFs, the proposed vapor-assisted, dry-gel method is efficient, simple, and inexpensive when compared to the conventional synthesis method.

  13. Development and validation of an LC-ESI-MS/MS approach to determine a highly hydrophobic drug, norcantharidin palmitate, and apply to a preliminary pharmacokinetic study in rats.

    Science.gov (United States)

    Liu, Xiaolin; Tao, Xiaoguang; Zheng, Qi; Xu, Hang; Zhang, Yu; Lei, Tian; Yin, Tian; He, Haibing; Tang, Xing

    2017-12-01

    In order to investigate the pharmacokinetics of norcantharidin palmitate (NCTD-PAL) in rats, we developed and validated an LC-ESI-MS/MS method. The NCTD-PAL and internal standard (triamcinoloneacetonide palmitate, TAP) were separated on a Phenomenex Kinetex®XB C18 column, and the mobile phase was composed of tetrahydrofuran (THF)-acetonitrile (20/80, v/v) and an aqueous phase containing 0.2% ammonium hydroxide at a flow rate of 0.3 mL/min. The ESI interface operated in positive mode was used to acquire the mass spectrometric data, and the transition ions were m/z 635.50 → 168.95 and 673.65 → 397.13 for NCTD-PAL and IS, respectively. The method had a linear range of 10-2000 ng/mL with a correlation coefficient of >0.99. The accuracy (RE, %) was within ±10.1%, and the intra- and inter-day precisions (RSD, %) were 10.9 and 13.8%, respectively. The extraction recovery of NCTD-PAL at different concentrations ranged from 89.3 to 102.0%. The validated approach was efficaciously applied to a pharmacokinetic study of NCTD-PAL in rats via intravenous injection. Based on these results obtained, this method is practical and suitable for a wide range of applications. Copyright © 2017 John Wiley & Sons, Ltd.

  14. Exploration and characterization of new synthesis methods for C60 colloidal suspensions in water

    Science.gov (United States)

    Hilburn, Martha E.

    Buckminsterfullerene, C60, has been used in the production of several commercial products from badminton racquets and lubricants for their mechanical properties to cosmetics and even dietary supplements for their "antioxidant" properties. Multi-ton production of C60 began in 2003 encouraging serious consideration of its fate in the environment in the case of an accidental release or improper disposal. Although C60 is practically insoluble in water, it readily forms stable aqueous colloidal suspensions (termed nC60) through solvent exchange methods or long-term vigorous stirring in water. Two new solvent exchange methods for synthesizing nC60 are presented. These methods combine key advantages of multiple existing synthesis methods including high yield, narrow particle size distribution, short synthesis time, and an absence of solvents such as tetrahydrofuran that have historically caused problems in laboratory synthesized aggregates. The resulting samples are attractive candidates for use in controlled environmental impact, biological, and toxicity studies. An improved method for quantifying residual solvents in nC60 samples utilizing solid phase micro extraction gas chromatography mass spectrometry (SPME-GC-MS) is also discussed.

  15. Self-aggregation behavior of synthetic zinc 3-hydroxymethyl-13/15-carbonyl-chlorins as models of main light-harvesting components in photosynthetic green bacteria.

    Science.gov (United States)

    Tamiaki, Hitoshi; Yoshimura, Hideaki; Shimamura, Yasuhide; Kunieda, Michio

    2008-01-01

    Zinc complexes of 3-hydroxymethyl-13/15-carbonyl-chlorins having a six-membered lactone as the E-ring were prepared by modifying purpurin-18 as models of bacteriochlorophyll-d, one of the chlorophyllous pigments in the main light-harvesting antenna systems (chlorosomes) of green photosynthetic bacteria. The synthetic 13-carbonylated compound self-aggregated in 1%(v/v) tetrahydrofuran and hexane to give large oligomers possessing red-shifted and broadened electronic absorption bands and intense circular dichroism bands at the shifted Q ( y ) region, indicating that the supramolecular structure of the resulting self-aggregate was similar to those of natural and artificial chlorosomal aggregates. The red-shift value observed here was smaller than the reported values in chlorosomal pigments having a five-membered keto-ring, which was ascribable to a weaker intermolecular hydrogen-bonding of 13-C=O with 3(1)-OH in a supramolecule of the former self-aggregate and suppression of the pi-pi interaction among the composite chlorins. On the other hand, the isomeric 15-carbonylated molecule was monomeric even in the nonpolar organic solvent, confirming the reported proposal that the linear orientation of three interactive moieties, OH, C=O and Zn, in a molecule is requisite for its chlorosomal self-aggregation.

  16. Separation of nonylphenol ethoxylates and nonylphenol by non-aqueous capillary electrophoresis.

    Science.gov (United States)

    Babay, Paola A; Gettar, Raquel T; Silva, María F; Thiele, Björn; Batistoni, Daniel A

    2006-05-26

    Capillary electrophoresis based on non-aqueous solvent background electrolytes was employed, with single and multiple wavelength UV detection, to evaluate discrimination among oligomer components of mixtures of non-ionic, long chain nonylphenol ethoxylates (NPnEO, with n = number of ethoxy units) and their lipophilic degradation products. The tested organic solvents included acetonitrile, methanol, ethanol, 1- and 2-propanol, 1-butanol and tetrahydrofurane in the presence of sodium acetate. A rational variation of composition of background electrolyte solvent mixtures allowed to modify the mobility of electroosmotic flow and the type and degree of interactions between the ionic additive (sodium acetate) and the components of the analyte mixtures. The physicochemical properties of the solvents, such as dielectric constant, viscosity and electron donor-acceptor ability regarding the additive, were considered to improve the resolution of lipophilic compounds with less than three ethoxy groups and the discrimination attainable for longer chain oligomers. The studied methodologies also allowed discerning between surfactants of similar (nominal) ethoxy chain lengths. This was demonstrated by the different peak distribution patterns observed for NPnEO compounds with n = 7.5 and 10, respectively.

  17. Planar-rotor architecture based pyrene-vinyl-tetraphenylethylene conjugated systems: photophysical properties and aggregation behavior.

    Science.gov (United States)

    Jana, Debabrata; Boxi, Shatabdi; Parui, Partha P; Ghorai, Binay K

    2015-11-21

    Four pyrene-vinyl-tetraphenylethylene based conjugated materials were synthesized and characterized by FT-IR, NMR, and mass spectroscopy. The photophysical (including absorption, fluorescence, and fluorescence lifetime) and aggregation properties in tetrahydrofuran were investigated. The photophysical and aggregation behavior depends on the spacer, substituent, and also the architecture (mono or tetra-branched) of the molecule. The vinyl spacer mono-branched compound is aggregation induced emission (AIE) active (αAIE = ∼6). Vinyl spacer tetra-branched compounds are AIE inactive, but their emitting efficiency is good in both solution (Φfl = 63%) phase and in the aggregated state (Φfl = 43%). Phenylvinyl spacer tetra-branched compounds emit light strongly in solution (Φfl = 92%), but not in the aggregated state (Φfl = 8%). They are shown to be thermally stable and emit light in the green region (500-550 nm). The results of cyclic voltammetry measurements of these materials showed irreversible oxidation waves, and have high HOMO energy levels (-5.66 to -5.53 eV).

  18. Unusual Emission of Polystyrene-Based Alternating Copolymers Incorporating Aminobutyl Maleimide Fluorophore-Containing Polyhedral Oligomeric Silsesquioxane Nanoparticles

    Directory of Open Access Journals (Sweden)

    Mohamed Gamal Mohamed

    2017-03-01

    Full Text Available In this study, we synthesized an unusual 2-aminobutyl maleimide isobutyl polyhedral oligomeric silsesquioxane (MIPOSS-NHBu monomer lacking conventional fluorescent groups. We then prepared poly(styrene-alt-2-aminobutyl maleimide isobutyl POSS [poly(S-alt-MIPOSS-NHBu] and poly(4-acetoxystyrene-alt-2-aminobutyl maleimide isobutyl POSS [poly(AS-alt-MIPOSS-NHBu] copolymers through facile free radical copolymerizations using azobisisobutyronitrile as the initiator and tetrahydrofuran as the solvent. A poly(4-hydroxystyrene-alt-2-aminobutyl maleimide isobutyl POSS [poly(HS-alt-MIPOSS-NHBu] copolymer was prepared through acetoxyl hydrazinolysis of poly(AS-alt-MIPOSS-NHBu. We employed 1H, 13C, and 29Si nuclear magnetic resonance spectroscopy; Fourier transform infrared spectroscopy; differential scanning calorimetry; and photoluminescence spectroscopy to investigate the structures and the thermal and optical properties of the monomers and novel POSS-containing alternating copolymers. Intramolecular hydrogen bonding between the amino and dihydrofuran-2,5-dione group and clustering of the locked C=O groups from the POSS nanoparticles in the MIPOSS-NHBu units restricted the intramolecular motion of the polymer chain, causing it to exhibit strong light emission. As a result, the MIPOSS-NHBu monomer and the poly(AS-alt-MIPOSS-NHBu copolymer both have potential applicability in the detection of metal ions with good selectivity.

  19. 1,3,4-Tri-O-acetyl-2-N-(trifluoroacetyl-β-l-fucose

    Directory of Open Access Journals (Sweden)

    David C. McCutcheon

    2014-02-01

    Full Text Available The title compound, C14H18F3NO8, was produced through conjugation of 1,3,4-tri-O-acetyl-2-azidodeoxy-α,β-l-fucose with trifluoroacetyl chloride in the presence of bis(diphenylphosphinoethane in tetrahydrofuran at room temperature. The X-ray crystal structure reveals that the β-anomer of the product mixture crystallizes from ethyl acetate/hexanes. The compound exists in a typical chair conformation with the maximum possible number of substituents, four out of five, located in the sterically preferred equatorial positions. The major directional force facilitating packing of the molecules are N—H...O hydrogen bonds involving the amide moieties of neighboring molecules, which connect molecules stacked along the a-axis direction into infinite strands with a C11(4 graph-set motif. Formation of the strands is assisted by a number of weaker C—H...O interactions involving the methine and methyl H atoms. These strands are connected through further C—H...O and C—H...F interactions into a three dimensional network

  20. High-Performance Near-Infrared Luminescent Solar Concentrators.

    Science.gov (United States)

    Rondão, Raquel; Frias, Ana R; Correia, Sandra F H; Fu, Lianshe; de Zea Bermudez, Verónica; André, Paulo S; Ferreira, Rute A S; Carlos, Luís D

    2017-04-12

    Luminescent solar concentrators (LSCs) appear as candidates to enhance the performance of photovoltaic (PV) cells and contribute to reduce the size of PV systems, decreasing, therefore, the amount of material needed and thus the cost associated with energy conversion. One way to maximize the device performance is to explore near-infrared (NIR)-emitting centers, resonant with the maximum optical response of the most common Si-based PV cells. Nevertheless, very few examples in the literature demonstrate the feasibility of fabricating LSCs emitting in the NIR region. In this work, NIR-emitting LSCs are reported using silicon 2,3-naphthalocyanine bis(trihexylsilyloxide) (SiNc or NIR775) immobilized in an organic-inorganic tri-ureasil matrix (t-U(5000)). The photophysical properties of the SiNc dye incorporated into the tri-ureasil host closely resembled those of SiNc in tetrahydrofuran solution (an absolute emission quantum yield of ∼0.17 and a fluorescence lifetime of ∼3.6 ns). The LSC coupled to a Si-based PV device revealed an optical conversion efficiency of ∼1.5%, which is among the largest values known in the literature for NIR-emitting LSCs. The LSCs were posteriorly coupled to a Si-based commercial PV cell, and the synergy between the t-U(5000) and SiNc molecules enabled an effective increase in the external quantum efficiency of PV cells, exceeding 20% in the SiNc absorption region.

  1. Crystal structure of 2-azido-1,3-bis(2,6-diisopropylphenyl-1,3,2-diazaphospholidine

    Directory of Open Access Journals (Sweden)

    Alex J. Veinot

    2017-06-01

    Full Text Available The title compound, C26H38N5P, was synthesized by reacting 2-chloro-1,3-bis(2,6-diisopropylphenyl-1,3,2-diazaphospholidine with sodium azide and a catalytic amount of lithium chloride in tetrahydrofuran. The title compound is the first structurally characterized 2-azido-1,3,2-diazaphospholidine and exhibits a P atom in a trigonal pyramidal geometry. The azide P—N bond length of 1.8547 (16 Å is significantly longer than the P—N separations for the chelating diamine [P—N = 1.6680 (15 and 1.6684 (14 Å]. The sterically hindered 2,6-diisopropylphenyl groups twist away from the central heterocycle, with dihedral angles between the central heteocyclic ring and benzene rings of 76.17 (10 and 79.74 (9°. In the crystal, a weak C—H...N link to the terminal N atom of the azide group leads to [100] chains.

  2. Thermophysical properties of binary mixtures of N,N-dimethylformamide with three cyclic ethers

    Directory of Open Access Journals (Sweden)

    Sinha Biswajit

    2013-01-01

    Full Text Available Densities and viscosities of the binary mixtures consisting of tetrahydrofuran (THF, 1,3-dioxolane (1,3-DO and 1,4-dioxane (1,4-DO with N,N-dimethylformamide (DMF over the entire range of composition were measured at temperatures 298.15, 308.15 and 318.15 K and at atmospheric pressure. Ultrasonic speeds of sound of these binary mixtures were measured at ambient temperature and atmospheric pressure (T = 298.15 K and P = 1.01×105 Pa. The various experimental data were utilized to derive excess molar volumes (VmE, excess viscosities (ηE, and excess isentropic compressibilities (κsE. Using the excess molar volumes (VmE, excess partial molar volumes (and and excess partial molar volumes at infinite dilution (and of each liquid component in the mixtures were derived and discussed. Excess molar volumes (VmE as a function of composition at ambient temperature and atmospheric pressure were used further to test the applicability of the Prigogine-Flory-Patterson (PFP theory to the experimental binaries. The excess properties were found to be either negative or positive depending on the nature of molecular interactions and structural effects of liquid mixtures. Em,1V Em,2VE0,m,1VE0,m,2V.

  3. 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.

  4. Does Synergism in Microscopic Polarity Correlate with Extrema in Macroscopic Properties for Aqueous Mixtures of Dipolar Aprotic Solvents?

    Science.gov (United States)

    Duereh, Alif; Sato, Yoshiyuki; Smith, Richard Lee; Inomata, Hiroshi; Pichierri, Fabio

    2017-06-22

    Aqueous mixtures of dipolar aprotic solvents (acetonitrile, γ-valerolactone, γ-butyrolactone, tetrahydrofuran, 1,4-dioxane, acetone, pyridine, N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide) show synergism in microscopic polarity and extrema in macroscopic viscosity (η) and molar excess enthalpy (H E ) in water-rich compositions that correlate with solvent functional group electrostatic basicity (β 2 H ). Microscopic polarities of aqueous solvent mixtures were estimated by measuring the spectral shift (λ max ) of 4-nitroaniline with UV-vis spectroscopy at 25 °C. Dynamic viscosities (η) and densities were measured for eight aqueous dipolar aprotic mixtures over the full range of compositions at (25 to 45) °C. The λ max , η, and H E values of the aqueous mixtures showed a linear trend with increasing electrostatic basicity of the solvent functional groups that is attributed to the size and strength of the hydration shell of water. Density functional theory (DFT) calculations were performed for 1:3 complexes (solvent: (H 2 O) 3 ) and it was found that aqueous mixtures with high basicity have high binding energies and short hydrogen bonding distances implying that the size and strength of the hydration shell of water is proportional to functional group basicity. Consideration of functional group basicity of dipolar aprotic solvents allows one to relate synergism in microscopic polarity to extrema in macroscopic properties for a wide range of aqueous dipolar aprotic solvent mixtures.

  5. Chemistry and bioactivity of Flos Magnoliae, a Chinese herb for rhinitis and sinusitis.

    Science.gov (United States)

    Shen, Y; Li, C G; Zhou, S F; Pang, E C K; Story, D F; Xue, C C L

    2008-01-01

    Flos Magnoliae (FM, Chinese name: Xin-yi) is one of the most commonly used Chinese medicinal herbs. It has a long history of clinical use for managing rhinitis, sinusitis and headache. More than 20 different FM species have been used clinically, which makes species identification and evaluation of pharmacological effects of individual chemical ingredients difficult. In this review, we have summarized the current knowledge on FM phytochemistry and its bioactivity activities. The bioactive compounds in FM include both lipid and water-soluble components. More than 90% of the essential components of FM species are terpenoids, including monoterpenes and sesquiterpenes. Lignans and neolignans including tetrahydrofurofuran, tetrahydrofuran and aryltetralin are also present in FM species. A small number of water-soluble compounds have been isolated from Magnolia flower buds, including a benzylisoquinoline alkaloid magnoflorine, an ester ethyl-E-p-hydroxyl-cinnamate and a flavonoid biondnoid. A wide range of pharmacological actions of FM have been reported, including anti-allergy, anti-inflammation and anti-microbial activity. The structure-activity relationship analysis revealed the influence of methylation at position 5 on the 3,7-dioxabicyclo-(3,3,0)-octane backbone of six lignans in antagonistic activities against platelet-activating factor. In addition, the trans stereoisomer fargesin had a much lower bioactivity than the cis stereoisomer demethoxyaschantin. Recent studies have been directed towards the isolation of other bioactive compounds. Further studies on FM may help to develop new anti-inflammatory and anti-allergic drugs.

  6. Groundwater Monitoring and Tritium-Tracking Plan for the 200 Area State-Approved Land Disposal Site

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, D. Brent

    2000-08-31

    The 200 Area State-Approved Land Disposal Site (SALDS) is a drainfield which receives treated wastewater, occasionally containing high levels of tritium from treatment of Hanford Site liquid wastes. Only the SALDS proximal wells (699-48-77A, 699-48-77C, and 699-48-77D) have been affected by tritium from the facility thus far; the highest activity observed (2.1E+6 pCi/L) occurred in well 699-48-77D in February 1998. Analytical results of groundwater geochemistry since groundwater monitoring began at the SALDS indicate that all constituents with permit enforcement limits have been below those limits with the exception of one measurement of total dissolved solids (TDS) in 1996. The revised groundwater monitoring sampling and analysis plan eliminates chloroform, acetone, tetrahydrofuran, benzene, and ammonia as constituents. Replicate field measurements will replace laboratory measurements of pH for compliance purposes. A deep companion well to well 699-51-75 will be monitored for tritium deeper in the uppermost aquifer.

  7. Ordered macroporous quercetin molecularly imprinted polymers: Preparation, characterization, and separation performance.

    Science.gov (United States)

    Feng, Yonggang; Liu, Qin; Ye, Lifang; Wu, Quanzhou; He, Jianfeng

    2017-02-01

    Ordered macroporous molecularly imprinted polymers were prepared by a combination of the colloidal crystal templating method and the molecular imprinting technique by using SiO2 colloidal crystal as the macroporogen, quercetin as the imprinting template, acrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross-linker and tetrahydrofuran as the solvent. Scanning electron microscopy and Brunauer-Emmett-Teller measurements show that the ordered macroporous molecularly imprinted polymers have a more regular macroporous structure, a narrower pore distribution and a greater porosity compared with the traditional bulk molecularly imprinted polymers. The kinetic and isothermal adsorption behaviors of the polymers were investigated. The results indicate that the ordered macroporous molecularly imprinted polymers have a faster intraparticle mass transfer process and a higher adsorption capacity than the traditional bulk molecularly imprinted polymers. The ordered macroporous molecularly imprinted polymers were further employed as a sorbent for a solid-phase extraction. The results show that the ordered macroporous molecularly imprinted polymers can effectively separate quercetin from the Gingko hydrolysate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Computational Insights on Sulfonamide Imprinted Polymers

    Directory of Open Access Journals (Sweden)

    Chartchalerm Isarankura-Na-Ayudhya

    2008-12-01

    Full Text Available Molecular imprinting is one of the most efficient methods for preparing synthetic receptors that possess user defined recognition properties. Despite general success of non-covalent imprinting for a large variety of templates, some groups of compounds remain difficult to tackle due to their structural complexity. In this study we investigate preparation of molecularly imprinted polymers that can bind sulfonamide compounds, which represent important drug candidates. Compared to the biological system that utilizes metal coordinated interaction, the imprinted polymer provided pronounced selectivity when hydrogen bond interaction was employed in an organic solvent. Computer simulation of the interaction between the sulfonamide template and functional monomers pointed out that although methacrylic acid had strong interaction energy with the template, it also possessed high non-specific interaction with the solvent molecules of tetrahydrofuran as well as being prone to self-complexation. On the other hand, 1-vinyl-imidazole was suitable for imprinting sulfonamides as it did not cross-react with the solvent molecules or engage in self-complexation structures.

  9. High performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry for V and Ni quantification as tetrapyrroles

    Energy Technology Data Exchange (ETDEWEB)

    Duyck, Christiane Beatrice, E-mail: cbduyck@vm.uff.br [Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), R. Marques de Sao Vicente, 225, Gavea, Rio de Janeiro, RJ, 22451-900 (Brazil); Universidade Federal Fluminense (UFF), Campus do Valonguinho, Outeiro de Sao Joao Batista, s/no, 24020-150, Niteroi, RJ (Brazil); Saint' Pierre, Tatiana Dillenburg; Miekeley, Norbert [Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), R. Marques de Sao Vicente, 225, Gavea, Rio de Janeiro, RJ, 22451-900 (Brazil); Oliveira da Fonseca, Teresa Cristina; Szatmari, Peter [Centro de Pesquisas Leopoldo A. Miguez de Mello da Petrobras (CENPES), Av. Horacio Macedo, 950, Cidade Universitaria, Rio de Janeiro, RJ, 21941-915 (Brazil)

    2011-05-15

    A method was developed for the determination of V and Ni as tetrapyrroles by High Performance Liquid Chromatography hyphenated to Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS) using reversed phase and elution gradient. Chlorinated solvents and tetrahydrofuran were investigated as regard to separation time and ICP-MS detection efficiencies. The final elution gradient program started from pure methanol to a mixture of 20:80 (v/v) chloroform:methanol. External quantification of V and Ni with inorganic standards by flow injection ICP-MS, used online with HPLC, resulted in 95% of recoveries. The Limits of Detection for V during methanol elution and for Ni during the 20% chloroform gradient elution were evaluated by their minimum detectable concentrations, which were, respectively, 5 {mu}g L{sup -1} and 8 {mu}g L{sup -1}. The methodology was applied to polar and resin fractions separated from a Brazilian crude oil and a sediment extract from an oil-polluted area in the Guanabara Bay, Rio de Janeiro, Brazil. Vanadium as tetrapyrroles represented the totality of V content in the polar fraction, whereas Ni was in different polar forms in the resin and sediment extract.

  10. [Simultaneous determination of 10 synthetic colorants in cosmetics by high performance liquid chromatography].

    Science.gov (United States)

    Liu, Haishan; Qian, Xiaoyan; Lü, Chunhu; Zhu, Xiaoyu; Chen, Xiaomei; Mo, Weimin

    2013-11-01

    A high performance liquid chromatographic method was developed for the simultaneous determination of 10 synthetic colorants in cosmetics. The cosmetics were extracted by the ultrasonic technique with tetrahydrofuran (THF), dimethyl sulfoxide (DMSO) and methanol sequentially. Then the extracts were centrifuged for purification and separated on an Eclipse XDB-C18 column (150 mm x 4.6 mm, 5 microm) with gradient elution by acetonitrile and 0.02 mol/L ammonium acetate (pH 4.60, adjusted with acetic acid). A diode array detector was used to determine the colorants with the wavelengths ranging from 417 nm to 640 nm. The linear relationships of the 10 colorants between the peak areas and the mass concentrations were obtained in the range of 0.5-20.0 mg/L (r > 0.999). The limits of quantitation ranged from 10 to 20 mg/kg. The average recoveries at three concentration levels ranged from 92.9% to 108.8% with the relative standard deviations in the range of 0.5% to 6.1% (n = 6). The method is simple, rapid and sensitive. It is suitable for the simultaneous determination of the 10 colorants in the oil cosmetics, cream cosmetics and powder cosmetics.

  11. Production, extraction and stabilization of lutein from microalga Chlorella sorokiniana MB-1.

    Science.gov (United States)

    Chen, Chun-Yen; Jesisca; Hsieh, Chienyan; Lee, Duu-Jong; Chang, Chien-Hsiang; Chang, Jo-Shu

    2016-01-01

    The efficiencies of extraction and preservation of lutein from microalgae are critical for the success of its commercialization. In this study, lutein was produced by Chlorella sorokiniana MB-1 via semi-batch mixotrophic cultivation. The microalgal biomass with a lutein content of 5.21mg/g was pretreated by bead-beating and high pressure cell disruption methods, and the lutein content was harvested by a reduced pressure extraction method. The effect of pretreatment, pressure, solvent type, extraction time and temperature on lutein recovery was investigated. Using high pressure pretreatment followed by extraction with tetrahydrofuran (THF) as solvent resulted in high lutein recovery efficiencies of 87.0% (20min) and 99.5% (40min) at 850mbar and 25°C. In contrast, using ethanol as the solvent, 86.2% lutein recovery was achieved under 450mbar, 35°C and 40min extraction. The extracted lutein was stabilized in olive oil or sunflower oil with half-lives of 53.1 and 63.8days, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. The stability and degradation kinetics of acetylsalicylic acid in different organic solutions revisited – an UHPLC–ESI-QTOF spectrometry study

    Directory of Open Access Journals (Sweden)

    Skibinski Robert

    2016-04-01

    Full Text Available Ultra high performance liquid chromatography (UHPLC, coupled with accurate quadrupole-time-of-flight (Q-TOF mass spectrometry, was used for the stability study of acetylsalicylic acid within a variety of different organic solutions: methanol, ethanol, propan-2-ol, acetonitrile, tetrahydrofuran and 1,4-dioxane. With the use of gradient elution chromatography and mass spectrometry detection in negative ionization, MS and MS/MS spectra were recorded simultaneously. In addition, quantitative, as well as qualitative analysis was performed during one assay. The stability of acetylsalicylic acid in such solutions was tested at room temperature, in a 12h period. In the work, in all cases, only one main degradation product, salicylic acid, was found. What is more, the work revealed that the degradation of aspirin in the tested organic solutions yields apparent second-order kinetics. The study also demonstrated that acetonitrile and 1,4-dioxane turned out to be the most stable solvents, and an above 80% of initial concentration of acetylsalicylic acid was found in this case. Furthermore, the most popular analytical solvents, methanol and ethanol, were found to be very unstable media. Herein, below 40% of initial concentration of acetylsalicylic acid was seen after 12h. The obtained results were also compared with the degradation of acetylsalicylic acid in a water solution. In this situation, only about 25% of the analyzed compound was resolved to salicylic acid in the same time frame.

  13. Double differential cross sections for proton induced electron emission from molecular analogues of DNA constituents for energies in the Bragg peak region

    Science.gov (United States)

    Rudek, Benedikt; Bennett, Daniel; Bug, Marion U.; Wang, Mingjie; Baek, Woon Yong; Buhr, Ticia; Hilgers, Gerhard; Champion, Christophe; Rabus, Hans

    2016-09-01

    For track structure simulations in the Bragg peak region, measured electron emission cross sections of DNA constituents are required as input for developing parameterized model functions representing the scattering probabilities. In the present work, double differential cross sections were measured for the electron emission from vapor-phase pyrimidine, tetrahydrofuran, and trimethyl phosphate that are structural analogues to the base, the sugar, and the phosphate residue of the DNA, respectively. The range of proton energies was from 75 keV to 135 keV, the angles ranged from 15° to 135°, and the electron energies were measured from 10 eV to 200 eV. Single differential and total electron emission cross sections are derived by integration over angle and electron energy and compared to the semi-empirical Hansen-Kocbach-Stolterfoht (HKS) model and a quantum mechanical calculation employing the first Born approximation with corrected boundary conditions (CB1). The CB1 provides the best prediction of double and single differential cross section, while total cross sections can be fitted with semi-empirical models. The cross sections of the three samples are proportional to their total number of valence electrons.

  14. Regenerable Subnanometer Pd Clusters on Zirconia for Highly Selective Hydrogenation of Biomass-Derived Succinic Acid in Water

    Directory of Open Access Journals (Sweden)

    Chi Zhang

    2016-07-01

    Full Text Available The size of metal particles is an important factor to determine the performance of the supported metal catalysts. In this work, we report subnanometer Pd clusters supported on zirconia by the microwave-assisted hydrothermal method. The presence of subnanometer Pd clusters on the zirconia surface was confirmed by two-dimensional Gaussian-function fits of the aberration-corrected high-angle annual dark-field images. These subnanometer Pd catalysts exhibit high catalytic performance for the hydrogenation of biomass-derived succinic acid to γ-butyrolactone in water and avoid the formation of overhydrogenated products, such as 1,4-butanediol and tetrahydrofuran. The catalyst with an ultra-low Pd loading of 0.2 wt. % demonstrated high selectivity (95% for γ-butyrolactone using water as a solvent at 473 K and 10 MPa. Moreover, it can be reused at least six times without the loss of catalytic activity, illustrating high performance of the small Pd clusters.

  15. Phosphazene-catalyzed ring-opening polymerization of ε-caprolactone: Influence of solvents and initiators

    KAUST Repository

    Alamri, Haleema

    2014-01-01

    Phosphazene base (t-BuP2) catalysed metal-free ring-opening polymerization of ε-caprolactone (ε-CL) at room temperature with various protic initiators in different solvents was investigated. The polymerization proceeded, in most cases, in a controlled manner to afford poly(ε-caprolactone) with low dispersities and expected molecular weights. Kinetic studies showed that when a primary alcohol was used as an initiator the polymerization rate in different solvents followed the order of dichloromethane ≫ toluene > 1,4-dioxane ≈ tetrahydrofuran. Extremely fast polymerization of l-lactide (LLA), which was added as a second monomer, was observed in different solvents giving rise to poly(ε-caprolactone)-b- poly(l-lactide) diblock copolymers with neat PLLA blocks despite incomplete conversion of ε-CL. The dependence of polymerization rate on the concentrations of ε-CL and t-BuP2 was also revealed. In addition to primary alcohol, the feasibility of using other protic initiators, such as secondary alcohol (either on a small molecule or a polymer chain-end), (aliphatic/aromatic) amide, carboxylic acid, phenol and thiophenol, was also investigated. These studies provided important information for designing a metal-free route towards polyester-based (bio)materials. © 2014 the Partner Organisations.

  16. Role and composition of the mobile phase in coal

    Energy Technology Data Exchange (ETDEWEB)

    Grint, A.; Mehani, S.; Trewhella, M.; Crook, M.J.

    1985-10-01

    Extraction of Pittsburgh and Illinois No. 6 coals with tetrahydrofuran to remove a significant proportion of the mobile phase resulted in the elimination of thermoplastic properties. Cocarbonization of these extracted residues with large polycondensed aromatic molecules such as decacyclene and coronene resulted in the restoration of thermoplastic properties. It is proposed that large thermally stable aromatic molecules can perform a similar role to the molecular entities present in the mobile phase of bituminous coals, and that the presence of hydroaromatic (hydrogen donor) species in the mobile phase is unnecessary for the development of thermoplastic properties. The ability of thermally stable polycondensed aromatics to confer thermoplastic properties to coal appears to be related either to their hydrogen shuttling or radical stabilization propensity. The amounts and chemical nature of extracts from four coals (lignitic to high-volatile bituminous) were investigated. With increasing rank, the yields, aromaticity and degree of ring condensation of the extract (the mobile phase) all increased. For the two bituminous coals studied, the majority of the mobile phase was shown to consist of these thermally stable polycondensed aromatic species. 29 references.

  17. The mechanism of cell-damaging reactive oxygen generation by colloidal fullerenes.

    Science.gov (United States)

    Markovic, Zoran; Todorovic-Markovic, Biljana; Kleut, Duska; Nikolic, Nadezda; Vranjes-Djuric, Sanja; Misirkic, Maja; Vucicevic, Ljubica; Janjetovic, Kristina; Isakovic, Aleksandra; Harhaji, Ljubica; Babic-Stojic, Branka; Dramicanin, Miroslav; Trajkovic, Vladimir

    2007-12-01

    Because of the ability to induce cell death in certain conditions, the fullerenes (C(60)) are potential anticancer and toxic agents. The colloidal suspension of crystalline C(60) (nano-C(60), nC(60)) is extremely toxic, but the mechanisms of its cytotoxicity are not completely understood. By combining experimental analysis and mathematical modelling, we investigate the requirements for the reactive oxygen species (ROS)-mediated cytotoxicity of different nC(60) suspensions, prepared by solvent exchange method in tetrahydrofuran (THF/nC(60)) and ethanol (EtOH/nC(60)), or by extended mixing in water (aqu/nC(60)). With regard to their capacity to generate ROS and cause mitochondrial depolarization followed by necrotic cell death, the nC(60) suspensions are ranked in the following order: THF/nC(60)>EtOH/nC(60)>aqu/nC(60). Mathematical modelling of singlet oxygen ((1)O(2)) generation indicates that the (1)O(2)-quenching power (THF/nC(60)fullerene crystals determines their ability to produce ROS and cause cell damage. These data could have important implications for toxicology and biomedical application of colloidal fullerenes.

  18. Biotransformation of sesaminol triglucoside to mammalian lignans by intestinal microbiota.

    Science.gov (United States)

    Jan, Kuo-Ching; Hwang, Lucy Sun; Ho, Chi-Tang

    2009-07-22

    Plant lignans occur widely in foods, with flaxseed recognized as their richest source. Some plant lignans can be converted by intestinal microbiota to the mammalian lignans, enterodiol and enterolactone, which may have protective effects against hormone-related diseases such as breast cancer. This study determined whether plant lignans in sesame seed, particularly sesaminol triglucoside (STG), could be metabolized to mammalian lignans. STG is a furofuran lignan with methylenedioxyphenyls. The transformation of furofuran lignans to mammalian lignans by intestinal microbiota involves the hydrolysis of glucoside, demethylenation of a methylene group, oxidation of dibenzylbutanediol to dibenzylbutyrolactone, and reductive cleavage of furofuran rings. STG has methylenedioxyphenyl moieties in their structures that may require additional oxidative demethylenation of the methylenedioxyphenyl ring for conversion to mammalian lignans. However, STG is metabolized, via intestinal microbiota, to a catechol moiety. The major STG metabolite was characterized as 4-[((3R,4R)-5-(6-hydroxybenzo[d][1,3]dioxol-5-yl)-4-(hydroxymethyl)tetrahydrofuran-3-yl)methyl]benzene-1,2-diol using NMR and mass spectrometry, and STG could be converted to enterolactone and enterodiol by rat intestinal microflora.

  19. Hydride as a leaving group in the reaction of pinacolborane with halides under ambient Grignard and Barbier conditions. One-pot synthesis of alkyl, aryl, heteroaryl, vinyl, and allyl pinacolboronic esters.

    Science.gov (United States)

    Clary, Jacob W; Rettenmaier, Terry J; Snelling, Rachel; Bryks, Whitney; Banwell, Jesse; Wipke, W Todd; Singaram, Bakthan

    2011-12-02

    Grignard reagents (aliphatic, aromatic, heteroaromatic, vinyl, or allylic) react with 1 equiv of 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (pinacolborane, PinBH) at ambient temperature in tetrahydrofuran (THF) to afford the corresponding pinacolboronates. The initially formed dialkoxy alkylborohydride intermediate quickly eliminates hydridomagnesium bromide (HMgBr) and affords the product boronic ester in very good yield. Hydridomagnesium bromide (HMgBr) in turn disproportionates to a 1:1 mixture of magnesium hydride (MgH(2)) and magnesium bromide (MgBr(2)) on addition of pentane to the reaction mixture. DFT calculations (Gaussian09) at the B3LYP/6-31G(d) level of theory show that disproportionation of HMgBr to MgH(2) and MgBr(2) is viable in the coordinating ethereal solvents. This reaction also can be carried out under Barbier conditions, where the neat PinBH is added to the flask prior to the in situ formation of Grignard reagent from the corresponding organic halide and magnesium metal. Pinacolboronic ester synthesis under Barbier conditions does not give Wurtz coupling side products from reactive halides, such as benzylic and allylic halides. The reaction between PinBH and various Grignard reagents is an efficient, mild, and general method for the synthesis of pinacolboronates. © 2011 American Chemical Society

  20. Development a novel supramolecular solvent microextraction procedure for copper in environmental samples and its determination by microsampling flame atomic absorption spectrometry.

    Science.gov (United States)

    Yilmaz, Erkan; Soylak, Mustafa

    2014-08-01

    A supramolecular solvent (Ss) made up of reverse micelles of 1-decanol in tetrahydrofuran (THF): water was used for the fast and selective microextraction of Cu(II) prior to its determination by microsampling flame atomic absorption spectrometry (FAAS). Cu(II) was complexed with dimethyl dithiocarbamate (DMDC) to obtain hydrophobic complex and extracted to supramolecular solvent phase. The influences of some analytical parameters including pH, type and volume of supramolecular solvent, amount of complexing agent, ultrasonication and centrifuge time and sample volume were investigated. The effects of matrix components were also examined. The detection limit (LOD) and the quantification limit (LOQ) were 0.52µg L(-1) and 1.71µg L(-1) respectively. An preconcentration factor was obtained as 60 and the relative standard deviation was <3%. The accuracy of the developed method was evaluated by the analysis of the certified reference materials (TMDA-64.2 water, SRM 1568A Rice Flour and 8433 Corn Bran) and addition-recovery tests. The presented supramolecular solvent based liquid-liquid microextraction (SsLLME) procedure was applied to the determination of copper in food and water samples with satisfactory results. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Study of electrical conductivity response upon formation of ice and gas hydrates from salt solutions by a second generation high pressure electrical conductivity probe.

    Science.gov (United States)

    Sowa, Barbara; Zhang, Xue Hua; Kozielski, Karen A; Dunstan, Dave E; Hartley, Patrick G; Maeda, Nobuo

    2014-11-01

    We recently reported the development of a high pressure electrical conductivity probe (HP-ECP) for experimental studies of formation of gas hydrates from electrolytes. The onset of the formation of methane-propane mixed gas hydrate from salt solutions was marked by a temporary upward spike in the electrical conductivity. To further understand hydrate formation a second generation of window-less HP-ECP (MkII), which has a much smaller heat capacity than the earlier version and allows access to faster cooling rates, has been constructed. Using the HP-ECP (MkII) the electrical conductivity signal responses of NaCl solutions upon the formation of ice, tetrahydrofuran hydrates, and methane-propane mixed gas hydrate has been measured. The concentration range of the NaCl solutions was from 1 mM to 3M and the driving AC frequency range was from 25 Hz to 5 kHz. This data has been used to construct an "electrical conductivity response phase diagrams" that summarize the electrical conductivity response signal upon solid formation in these systems. The general trend is that gas hydrate formation is marked by an upward spike in the conductivity at high concentrations and by a drop at low concentrations. This work shows that HP-ECP can be applied in automated measurements of hydrate formation probability distributions of optically opaque samples using the conductivity response signals as a trigger.

  2. High molar activity of [{sup 11}C]TCH346 via [{sup 11}C]methyl triflate using the 'wet' [{sup 11}C]CO{sub 2} reduction method

    Energy Technology Data Exchange (ETDEWEB)

    Ermert, Johannes [Institut fuer Neurowissenschaften und Biophysik: Nuklearchemie, Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany)], E-mail: j.ermert@fz-juelich.de; Stuesgen, Stefan; Lang, Markus; Roden, Werner; Coenen, Heinz H. [Institut fuer Neurowissenschaften und Biophysik: Nuklearchemie, Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany)

    2008-05-15

    [{sup 11}C]TCH346, a compound acting on the glycolytic enzyme, glycerol-aldehyde-3-phosphate dehydrogenase, was produced under optimised conditions by methylation of the desmethyl compound with no-carrier added (n.c.a.) [{sup 11}C]methyl triflate. An i.v. injectable solution of n.c.a. [{sup 11}C]TCH346 containing 4040{+-}1550 MBq (n=6) containing a molar activity between 40 and 5700 GBq/{mu}mol and a radiochemical purity of >99% was obtained within 30 min (after EOB) by irradiation of nitrogen gas containing 0.5% oxygen with 16.5 MeV protons at 45 {mu}A for 30 min. The alkylation reagent [{sup 11}C]methyl triflate was prepared via on-line conversion of [{sup 11}C]methyl iodide. For the formation of [{sup 11}C]methyl iodide, [{sup 11}C]carbon dioxide from the target chamber was reduced by a lithium aluminium hydride solution, and the methanol obtained on-line was converted using triphenylphosphine diiodide. The molar activity of [{sup 11}C]TCH346 could be improved from 40 up to nearly 5700 GBq/{mu}mol during the optimisation of the synthesis using the same stock solution of lithium aluminium hydride solution in tetrahydrofuran.

  3. Inorganic chemistry. Synthesis and characterization of P₂N₃⁻: an aromatic ion composed of phosphorus and nitrogen.

    Science.gov (United States)

    Velian, Alexandra; Cummins, Christopher C

    2015-05-29

    Aromaticity is predominantly associated with carbon-rich compounds but can also occur in all-inorganic ones. We report the synthesis of the diphosphatriazolate anion, a rare example of a planar aromatic inorganic species. Treatment of azide (N3(-)) in tetrahydrofuran solution with P2A2 (A = C14H10), a source of P2, produced P2N3(-), which we isolated as its [Na-kryptofix-221](+) salt in 22% yield and characterized by single-crystal x-ray diffraction. Salts [Na-kryptofix-221] [P2N3] and [Na-kryptofix-221] [P2(15)NN2] were analyzed by infrared and Raman spectroscopy, (15)N and (31)P nuclear magnetic resonance spectroscopy, and mass spectrometry. The formation of the P2N3(-) anion was investigated using density functional theory, and its aromatic character was confirmed by NICS (nucleus-independent chemical shift) and QTAIM (quantum theory of atoms in molecules) methods. Copyright © 2015, American Association for the Advancement of Science.

  4. Selective cholesterol adsorption by molecular imprinted polymeric nanospheres and application to GIMS.

    Science.gov (United States)

    Inanan, Tülden; Tüzmen, Nalan; Akgöl, Sinan; Denizli, Adil

    2016-11-01

    Molecular imprinted polymers (MIPs) are tailor-made materials with selective recognition to the target. The goals of this study were to prepare cholesterol imprinted polymeric nanospheres (CIPNs) and optimize their adsorption parameters and also to use CIPNs for adsorption of cholesterol (CHO), which is an important physiological biomacromolecule, from gastrointestinal mimicking solution (GIMS). Pre-polymerization complex was prepared using CHO as template and N-methacryloylamido-(l)-phenylalanine methyl ester (MAPA). This complex was polymerized with 2-hydroxyethyl methacrylate (HEMA). CHO was removed by MeOH and tetrahydrofuran (THF). Adsorption studies were performed after chacterization studies to interrogate the effects of time, initial concentration, temperature, and ionic strength on CHO adsorption onto CIPNs. Maximum adsorption capacity (714.17mg/g) was higher than that of cholesterol imprinted polymers in literature. Pseudo-second-order kinetics and Langmuir isotherm fitted best with the adsorption onto CIPNs. 86% of adsorbed cholesterol was desorbed with MeOH:HAc (80:20, v/v) and CIPNs were used in adsorption-desorption cycle for 5-times with a decrease as 12.28%. CHO analogues; estron, estradiol, testosterone, and progesterone were used for competitive adsorption. The relative selectivity coefficients of CINPs for cholesterol/estron and cholesterol/testosterone were 3.84 and 10.47 times greater than the one of non-imprinted polymeric nanospheres (NIPNs) in methanol, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Fluorine-Containing ABC Linear Triblock Terpolymers: Synthesis and Self-assembly in Solution

    Energy Technology Data Exchange (ETDEWEB)

    He, Lihong [ORNL; Hinestrosa Salazar, Juan P [ORNL; Pickel, Joseph M [ORNL; Kilbey, II, S Michael [ORNL; Mays, Jimmy [ORNL; Zhang, Shanju [Georgia Institute of Technology; Bucknall, David G. [Georgia Institute of Technology; Hong, Kunlun [ORNL

    2011-01-01

    In this paper a fluorine-containing monomer, 2-fluroroethyl methacrylate (2FEMA) was used to synthesize the linear triblock terpolymer poly(n-butyl methacrylate)-poly(methyl methacrylate)-poly(2-fluoroethyl methacrylate) (PnBMA-PMMA-P2FEMA). A kinetic study of the homopolymerization of 2FEMA by reversible addition-fragmentation chain transfer (RAFT) polymerization showed that it demonstrates living character and produces well defined polymers with reasonably narrow polydispersities (~1.30). Triblock terpolymers were prepared sequentially using a purified Macro-CTA at 70 oC, resulting in final terpolymers with high Dp for each block (>150) and with polydispersities between 1.6 and 2.1. The structure and molecular weights of the resultant PnBMA-PMMA-P2FEMA triblock terpolymers were characterized via 1H NMR, 19F NMR, and gel permeation chromatography (GPC). Self-assembly of these polymers was carried out in a selective solvent and the micellar aggregates (MAs) thereby formed were analyzed using scanning electron microscopy (SEM) and dynamic light scattering (DLS). It was confirmed from SEM that these copolymers could directly self-organize into large compound micelles in tetrahydrofuran/methanol with different diameters, depending on polymer composition.

  6. Mode of action and human relevance of THF-induced mouse liver tumors.

    Science.gov (United States)

    Choi, Christopher J; Rushton, Erik K; Vardy, Audrey; Higgins, Larry; Augello, Andrea; Parod, Ralph J

    2017-07-05

    In a National Toxicology Program (NTP) bioassay, inhalation of tetrahydrofuran (THF) induced liver tumors in female B6C3F1 mice but not in male mice or rats of either sex. Since THF is not genotoxic, the NTP concluded this carcinogenic activity was likely mediated via non-genotoxic modes of action (MOA). Based on evidence that THF and phenobarbital share a similar MOA, female Car/Pxr knock-out mice were orally exposed to THF to evaluate the potential role of CAR activation in the MOA for THF-induced liver tumors. Because data from this oral study with Car/Pxr knock-out mice (C57Bl/6) and the inhalation studies with wild type mice (B6C3F1) reported by NTP and others were derived from different strains, oral studies with wild type B6C3F1 and C57Bl/6 mice were conducted to ensure THF responses in both strains were comparable. As seen in inhalation studies with THF, oral exposure of wild type female mice to a maximum tolerated dose of THF increased total P450 content, CAR-related P450 activities, and hepatocyte proliferation; these effects were not observed in Car/Pxr knock-out female mice. This finding supports the hypothesis THF-induced carcinogenicity is likely mediated via CAR activation that has limited, if any, relevance to humans. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  7. Direct observation of breaking of the intramolecular H-bond, and slowing down of the proton motion and tuning its mechanism in an HBO derivative.

    Science.gov (United States)

    Alarcos, Noemí; Gutiérrez, Mario; Liras, Marta; Sánchez, Félix; Moreno, Miquel; Douhal, Abderrazzak

    2015-06-14

    We report on spectroscopic and photodynamical behaviours of 5-amino-2-(2'-hydroxyphenyl)benzoxazole (5A-HBO) in different solutions. The dye undergoes an ultrafast ICT reaction (hydrogen bond (IHB). 5A-HBO in n-heptane solution exhibits an irreversible and slow (20 ps) ESIPT reaction, while that of the parent compound, HBO, takes place in less than 150 fs. Compared to excited HBO behaviour, theoretical calculations on 5A-HBO suggest a higher energy barrier (∼4 kcal mol(-1)) between the relaxed enol and keto tautomers, in addition to a less stabilization of the latter, which is in agreement with experiments in n-heptane. On the other hand, in dichloromethane, after the ICT reaction a subsequent and reversible proton motion occurs in an extraordinary slower regime (ns-time scale). No isotopic effect (OH/OD exchange) was observed in this solvent reflecting that the reversible ESIPT reaction evolves along the IHB and solvent coordinates. Using tetrahydrofurane and acetonitrile, we observed a breaking of the IHB due to specific intermolecular interactions with solvent molecules. This leads to the formation of open-enol forms, which undergo an ICT reaction as it occurs in 5A-MBO. These results bring new findings in the coupled ICT and ESIPT reactions. The photobehaviour of this new dye remarkably changes with the solvent nature, opening up the window for further research and possible applications in sensing polarity or H-bonding of media similar to that of the biological ones.

  8. [N,N′-Bis(2,6-diisopropylphenylmethanimidamidato][η8-1,4-bis(trimethylsilylcyclooctatetraenyl](tetrahydrofuransamarium(III toluene monosolvate

    Directory of Open Access Journals (Sweden)

    Anja Edelmann

    2010-12-01

    Full Text Available The title compound, [Sm(C25H35N2(C14H24Si2(C4H8O]·C7H8, was prepared by treatment of anhydrous samarium trichloride with a 1:1 mixture of in situ-prepared Li(DippForm [DippFormH = N,N′-bis(2,6-diisopropylphenylmethanimidamide] and Li2(COT′′ [COT′′ = 1,4-bis(trimethylsilylcyclooctatetraenyl] in tetrahydrofuran (THF. Despite the presence of two very bulky ligands (COT′′ and DippForm, the molecule still contains one coordinated THF ligand. The overall coordination geometry around the SmIII atom resembles a three-legged piano-stool with the COT′′ ligand being η8-coordinated and the DippForm− anion acting as an N,N′-chelating ligand [Sm—N = 2.5555 (15 and 2.4699 (15 Å]. The asymmetric unit also contains a disordered molecule of toluene, the refined ratio of the two components being 0.80 (4:0.20 (4.

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

    Directory of Open Access Journals (Sweden)

    Ariadna Fuente-Hernández

    2017-02-01

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

  10. Electrical and spectroscopic characterization of polyaniline-polyvinyl chloride (PANI-PVC) blends doped with sodium thiosulphate

    Energy Technology Data Exchange (ETDEWEB)

    Ameen, Sadia [Department of Physics, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025 (India); Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Ali, Vazid; Zulfequar, M. [Department of Physics, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025 (India); Mazharul Haq, M. [Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Husain, M. [Department of Physics, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025 (India)], E-mail: mush_reslab@rediffmail.com

    2008-08-01

    Polyaniline is doped with sodium thiosulphate in aqueous tetrahydrofuran (THF) and the blended films have been prepared by changing the amount of doped polyaniline (PANI) in the fixed amount of polyvinyl chloride (PVC). The electrical conductivity of various samples of polyaniline-polyvinyl chloride (PANI-PVC) blends has been studied to see the effect of dopant in the temperature range 300-400 K. Mott's parameters are used to explain the conduction mechanism. Different parameters such as pre-exponential factor ({sigma}{sub 0}), activation energy ({delta}E) and T{sub 0} have also been calculated to see the effect of chemical doping. The crystallinity of the blends is explained on the basis of T{sub 0}. The calculated values of T{sub 0} show that crystallinity increases with an increase of doped PANI in PANI-PVC blends. Fourier transform-infrared (FTIR) spectroscopy is done to explore the nature and interaction of dopant into the polymeric chain.

  11. Estimating thermal diffusivity and specific heat from needle probe thermal conductivity data

    Science.gov (United States)

    Waite, W.F.; Gilbert, L.Y.; Winters, W.J.; Mason, D.H.

    2006-01-01

    Thermal diffusivity and specific heat can be estimated from thermal conductivity measurements made using a standard needle probe and a suitably high data acquisition rate. Thermal properties are calculated from the measured temperature change in a sample subjected to heating by a needle probe. Accurate thermal conductivity measurements are obtained from a linear fit to many tens or hundreds of temperature change data points. In contrast, thermal diffusivity calculations require a nonlinear fit to the measured temperature change occurring in the first few tenths of a second of the measurement, resulting in a lower accuracy than that obtained for thermal conductivity. Specific heat is calculated from the ratio of thermal conductivity to diffusivity, and thus can have an uncertainty no better than that of the diffusivity estimate. Our thermal conductivity measurements of ice Ih and of tetrahydrofuran (THF) hydrate, made using a 1.6 mm outer diameter needle probe and a data acquisition rate of 18.2 pointss, agree with published results. Our thermal diffusivity and specific heat results reproduce published results within 25% for ice Ih and 3% for THF hydrate. ?? 2006 American Institute of Physics.

  12. Characterization of surface hydrophobicity of engineered nanoparticles.

    Science.gov (United States)

    Xiao, Yao; Wiesner, Mark R

    2012-05-15

    The surface chemistry of nanoparticles, including their hydrophobicity, is a key determinant of their fate, transport and toxicity. Engineered NPs often have surface coatings that control the surface chemistry of NPs and may dominate the effects of the nanoparticle core. Suitable characterization methods for surface hydrophobicity at the nano-scale are needed. Three types of methods, surface adsorption, affinity coefficient and contact angle, were investigated in this study with seven carbon and metal based NPs with and without coatings. The adsorption of hydrophobic molecules, Rose Bengal dye and naphthalene, on NPs was used as one measure of hydrophobicity and was compared with the relative affinity of NPs for octanol or water phases, analogous to the determination of octanol-water partition coefficients for organic molecules. The sessile drop method was adapted for measuring contact angle of a thin film of NPs. Results for these three methods were qualitatively in agreement. Aqueous-nC(60) and tetrahydrofuran-nC(60) were observed to be more hydrophobic than nano-Ag coated with polyvinylpyrrolidone or gum arabic, followed by nano-Ag or nano-Au with citrate-functionalized surfaces. Fullerol was shown to be the least hydrophobic of seven NPs tested. The advantages and limitations of each method were also discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. NMR studies of molecules in liquid crystals and graphite

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, M.E.

    1992-06-01

    NMR experiments to measure proton dipole couplings were performed on a series of n-alkanes (n-hexane through n-decane) dissolved in nematic liquid crystals. Computer modeling of the experimental NMR-spectra was done using several different models for intermolecular interactions in these systems. The model of Photinos et al. was found to be best in describing the intermolecular interactions in these systems and can provide a statistical picture of the conformation and orientation of the alkane molecules in their partially-oriented environment. Order parameters and conformational distributions for the alkanes can be calculated from the modeling. The alkanes are found to have conformational distributions very much like those found in liquid alkanes. Proton NMR spectra of tetrahydrofuran (THF) intercalated in two graphite intercalation compounds were also measured. Computer simulations of these spectra provide a picture of THF in the constrained environment between the graphene layers where the THF is oriented at a particular angle, can translate and rotate freely, but does not appear to pseudorotate.

  14. Electrospun Carbon Nanotube-Reinforced Nanofiber.

    Science.gov (United States)

    Kim, Sung Mm; Hee Kim, Sung; Choi, Myong Soo; Lee, Jun Young

    2016-03-01

    We fabricated multi-walled carbon nanotube (MWNT) reinforced polyurethane (PU) nanofiber (MWNT-PU) web via electrospinning. In order to optimize the electrospinning conditions, we investigated the effects of various parameters including kind of solvent, viscosity of the spinning solution, and flow rate on the spinnability and properties of nanofiber. N,N-dimethylformamide (DMF), tetrahydrofuran (THF) and their mixture with various volume ratio were used as the spinning solvent. Morphology of the nanofiber was studied using scanning electron microscope (SEM) and transmission electron microscope (TEM), confirming successful fabrication of MWNT-PU nanofiber web with uniform dispersion of MWNT in longitudinal direction of the fiber. The MWNT-PU nanofiber web exhibited two times higher tensile strength than PU nanofiber web. We also fabricated electrically conducting MWNT-PU nanofiber web by coating poly(3,4-ehtylenedioxythiophene) (PEDOT) on the surface of MWNT-PU nanofiber web for electromagnetic interference (EMI) shielding application. The electromagnetic interference shielding effectiveness (EMI SE) was quite high as 25 dB in the frequency range from 50 MHz to 10 GHz.

  15. Substrate interactions during the biodegradation of BTEX and THF mixtures by Pseudomonas oleovorans DT4.

    Science.gov (United States)

    Zhou, Yu-Yang; Chen, Dong-Zhi; Zhu, Run-Ye; Chen, Jian-Meng

    2011-06-01

    The efficient tetrahydrofuran (THF)-degrading bacterium, Pseudomonas oleovorans DT4 was used to investigate the substrate interactions during the aerobic biotransformation of THF and BTEX mixtures. Benzene and toluene could be utilized as growth substrates by DT4, whereas cometabolism of m-xylene, p-xylene and ethylbenzene occurred with THF. In binary mixtures, THF degradation was delayed by xylene, ethylbenzene, toluene and benzene in descending order of inhibitory effects. Conversely, benzene (or toluene) degradation was greatly enhanced by THF leading to a higher degradation rate of 39.68 mg/(h g dry weight) and a shorter complete degradation time about 21 h, possibly because THF acted as an "energy generator". Additionally, the induction experiments suggested that BTEX and THF degradation was initiated by independent and inducible enzymes. The transient intermediate hydroquinone was detected in benzene biodegradation with THF while catechol in the process without THF, suggesting that P. oleovorans DT4 possessed two distinguished benzene pathways. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. HPLC determination and clinical significance of serum prednisone in patients with nephrotic syndrome

    Science.gov (United States)

    Chen, Chun-Mei; Xia, Yun-Cheng; Zhang, Xu-Guang; Peng, Can-Hui; Liu, Fu-You; Peng, You-Ming; Sun, Lin

    2014-01-01

    Aim: A rapid protocol is necessary to determine the serum concentrations of prednisone. Methods: The HP1100 high-performance liquid chromatographic (HPLC) system was employed. The HP Lichrosphere C8 column (250 mm × 4 mm, i.d., 5 μm particle size) was used. The mobile phase was methanol, tetrahydrofuran and water in the ratio 25:25:50. The flow rate was 1.0 ml/min. The sample was monitored by UV absorbance at 240 nm. Acetanilide was used as the internal standard, and methanol was added into the serum for depositing the protein. Results: The chromatography was effective and was not interfered with by the serum components. Good linearity was observed, within the range of 10-500 μg/L for prednisone, and the detection limit was 5 μg/L. The serum concentrations of prednisone between the nephrotic syndrome (NS) group and the control group were significantly different (P 0.05). The serum ncentration of prednisone in the steroid-resistant group was lower than that in the steroid-sensitive group (P < 0.05). Conclusions: HPLC is a practical and reliable method to determine the serum concentration of prednisone with high accuracy, precision, linearity and repeatability. PMID:25664064

  17. Group type analysis of asphalt by column liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, C.; Yang, J.; Xue, Y.; Li, Y. [Chinese Academy of Science, Taiyuan (China)

    2008-07-01

    An improved analysis method for characterization of asphalt was established. The method is based on column chromatography technique. The asphalts were separated into four groups: saturates, aromatics, resins, and asphaltenes, quantitatively. About 0.1 g of sample was required in each analysis. About 20 mL of n-heptanes was used to separate out saturates first. Then about 35 mL of n-heptanes/dichloromethane (.5, v/v) mixture was used to separate out aromatics. About 30 mL of dichloromethane/tetrahydrofuran (1/3, v/v) mixture was used to separate out resin. The quality of the separation was confirmed by infrared spectra (IR) and {sup 1}H NMR analysis. The model compounds, tetracosan for saturates, dibenz(o)anthracen for aromatics, and acetanilide for resins were used for verification. The IR and {sup 1}H NMR analysis of the prepared fractions from the column liquid chromatography were in good agreement that of pure reagents.

  18. Controlling Morphology and Aggregation in Semiconducting Polymers: The Role of Solvents on Lasing Emission in Poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene].

    Science.gov (United States)

    Liu, Minghuan; Liu, Yonggang; Peng, Zenghui; Yang, Chengliang; Mu, Quanquan; Cao, Zhaoliang; Ma, Ji; Xuan, Li

    2017-06-29

    Systematic experiments were performed to investigate solvent-dependent morphology and aggregation of the semiconducting polymer film poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene] (MEH-PPV), which was span-cast from nonaromatic strong polarity solvents tetrahydrofuran (THF), trichloromethane (TCM) and aromatic weak polarity solvents chlorobenzene (CB), toluene, and p-xylene. The results indicated that the conformation of the spin-cast MEH-PPV films with weak aggregation such as THF and TCM demonstrated excellent lasing emission performances because of inhibiting the fluorescence quenching induced by bi-molecule process. The Atomic Force Microscope (AFM) images confirmed the distinct morphologies of the spin-cast MEH-PPV films. The amplified spontaneous emission (ASE) was investigated in a simple asymmetric slab planar waveguide structure by methods of variable stripe length (VSL) and shifting excitation stripe (SES). The amplified spontaneous emission (ASE) experiments confirmed the distinct polymer chain conformation. The conformation, which preserved from the spin-cast process, indicated the distinct interactions between solvents and MEH-PPV polymer chains. The pure film spectra were performed to confirm the effect of distinct conformation on the material energy level. This work provides insights into the morphology and aggregation effect of the spin-cast polymer films on the performances of lasers.

  19. EFFECT OF FUEL IMPURITIES ON FUEL CELL PERFORMANCE AND DURABILITY

    Energy Technology Data Exchange (ETDEWEB)

    Colon-Mercado, H.

    2010-09-28

    A fuel cell is an electrochemical energy conversion device that produces electricity during the combination of hydrogen and oxygen to produce water. Proton exchange membranes fuel cells are favored for portable applications as well as stationary ones due to their high power density, low operating temperature, and low corrosion of components. In real life operation, the use of pure fuel and oxidant gases results in an impractical system. A more realistic and cost efficient approach is the use of air as an oxidant gas and hydrogen from hydrogen carriers (i.e., ammonia, hydrocarbons, hydrides). However, trace impurities arising from different hydrogen sources and production increases the degradation of the fuel cell. These impurities include carbon monoxide, ammonia, sulfur, hydrocarbons, and halogen compounds. The International Organization for Standardization (ISO) has set maximum limits for trace impurities in the hydrogen stream; however fuel cell data is needed to validate the assumption that at those levels the impurities will cause no degradation. This report summarizes the effect of selected contaminants tested at SRNL at ISO levels. Runs at ISO proposed concentration levels show that model hydrocarbon compound such as tetrahydrofuran can cause serious degradation. However, the degradation is only temporary as when the impurity is removed from the hydrogen stream the performance completely recovers. Other molecules at the ISO concentration levels such as ammonia don't show effects on the fuel cell performance. On the other hand carbon monoxide and perchloroethylene shows major degradation and the system can only be recovered by following recovery procedures.

  20. Parametric study of the physical properties of hydrate-bearing sand, silt, and clay sediments: 1. Electromagnetic properties

    Science.gov (United States)

    Lee, J.Y.; Santamarina, J.C.; Ruppel, C.

    2010-01-01

    The marked decrease in bulk electrical conductivity of sediments in the presence of gas hydrates has been used to interpret borehole electrical resistivity logs and, to a lesser extent, the results of controlled source electromagnetic surveys to constrain the spatial distribution and predicted concentration of gas hydrate in natural settings. Until now, an exhaustive laboratory data set that could be used to assess the impact of gas hydrate on the electromagnetic properties of different soils (sand, silt, and clay) at different effective stress and with different saturations of hydrate has been lacking. The laboratory results reported here are obtained using a standard geotechnical cell and the hydrate-formed tetrahydrofuran (THF), a liquid that is fully miscible in water and able to produce closely controlled saturations of hydrate from dissolved phase. Both permittivity and electrical conductivity are good indicators of the volume fraction of free water in the sediment, which is in turn dependent on hydrate saturation. Permittivity in the microwave frequency range is particularly predictive of free water content since it is barely affected by ionic concentration, pore structure, and surface conduction. Electrical conductivity (or resistivity) is less reliable for constraining water content or hydrate saturation: In addition to fluid-filled porosity, other factors, such as the ionic concentration of the pore fluid and possibly other conduction effects (e.g., surface conduction in high specific surface soils having low conductivity pore fluid), also influence electrical conductivity.