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Sample records for 2-methylpropane

  1. Vibrational analysis of 1,2-dichloro-2-methylpropane and 1,2-dibromo-2-methylpropane

    NASA Astrophysics Data System (ADS)

    Crowder, G. A.; Richardson, Mary Townsend

    1982-02-01

    Liquid-state IR and Raman spectra and solid-state IR spectra have been obtained for 1,2-dichloro-2-methylpropane and l,2-dibromo-2-methylpropane. Carbon-halogen stretching bands are observed in the liquid-state spectrum of the dichloro compound at 751, 725, 624 and 574 cm -1 and at 677, 640, 551 and 507 cm -1 in the liquid-state spectrum of the dibromo compound. Both compounds exist as P CTt HHH and P XT XHH conformations in the liquid, but only the P XT XHH conformer is present for each in the crystalline solid. Further Interpretation of the spectra was aided by normal coordinate calculations.

  2. Synthesis and properties of poly(methyl methacrylate-2-acrylamido-2-methylpropane sulfonic acid)/PbS hybrid composite

    SciTech Connect

    Preda, N.; Rusen, E.; Musuc, A.; Enculescu, M.; Matei, E.; Marculescu, B.; Fruth, V.; Enculescu, I.

    2010-08-15

    The synthesis of a new hybrid composite based on PbS nanoparticles and poly(methyl methacrylate-2-acrylamido-2-methylpropane sulfonic acid) [P(MMA-AMPSA)] copolymer is reported. The chemical synthesis consists in two steps: (i) a surfactant-free emulsion copolymerization between methyl methacrylate and 2-acrylamido-2-methylpropane sulfonic acid and (ii) the generation of PbS particles in the presence of the P(MMA-AMPSA) latex, from the reaction between lead nitrate and thiourea. The composite was studied by scanning electron microscopy (SEM), X-ray diffraction, FTIR spectroscopy, thermogravimetric analysis and differential scanning calorimetry. The microstructure observed using SEM proves that the PbS nanoparticles are well dispersed in the copolymer matrix. The X-ray diffraction measurements demonstrate that the PbS nanoparticles have a cubic rock salt structure. It was also found that the inorganic semiconductor nanoparticles improve the thermal stability of the copolymer matrix.

  3. Quasielastic electron scattering from methane, methane-d4, methane-d2, ethylene, and 2-methylpropane

    NASA Astrophysics Data System (ADS)

    Cooper, G.; Christensen, E.; Hitchcock, A. P.

    2007-08-01

    Quasielastic electron scattering from gaseous species at high momentum transfer was recently reported for the first time [Cooper et al., J. Electron Spectrosc. Relat. Phenom. 155, 28 (2007)]. The first results for CH4 and CD4 were well explained by a classical electron Compton scattering picture in which the electron scatters independently from each atom rather than the molecule as a whole. However, an alternative possible interpretation in terms of nondipole molecular vibrational excitation is suggested by previously published quantum mechanical calculations on high momentum transfer electron scattering from diatomic molecules [Bonham and de Souza, J. Chem. Phys. 79, 134 (1983)]. In order to determine which of these two interpretations best fits the experimental results, we have measured the quasielastic spectra of gaseous 2-methylpropane, ethylene, methane, and two isotopically substituted methanes, CH2D2 and CD4, at a momentum transfer of ˜20a.u. (2.25keV impact energy and 100° scattering angle). The experimental spectra are found to be composed of as many peaks as there are different atomic isotopes in the molecule (two for CH4, C2H4, 2-methylpropane, and CD4 and three for CH2D2). The peak positions are predicted accurately by the independent atom electron Compton scattering model, and the relative intensities are in reasonable agreement. The experimental results thus support classical electron Compton scattering as the origin of the signal.

  4. Synthesis and evaluation of poly(Sodium 2-Acrylamido-2-Methylpropane Sulfonate-co-Styrene)/magnetite nanoparticle composites as corrosion inhibitors for steel.

    PubMed

    El-Mahdy, Gamal A; Atta, Ayman M; Al-Lohedan, Hamad A

    2014-01-01

    Self-stabilized magnetic polymeric composite nanoparticles of coated poly-(sodium 2-acrylamido-2-methylpropane sulfonate-co-styrene)/magnetite (PAMPS-Na-co-St/Fe3O4) were prepared by emulsifier-free miniemulsion polymerization using styrene (St) as a monomer, 2-acrylamido-2-methylpropane sulfonic acid sodium salt (AMPS-Na) as an ionic comonomer, N,N-methylenebisacrylamide (MBA) as crosslinker, hexadecane (HD) as a hydrophobic solvent, and 2,2-azodiisobutyronitrile (AIBN) as an initiator in the presence of hydrophobic oleic acid coated magnetite particles. Hydrophobic oleic acid coated magnetite particles with an average size of about 7-10 nm were prepared with the new modified water-based magnetite ferrofluid, synthesized by a chemical modified coprecipitation method. The morphology and the particle size distributions of the crosslinked PAMPS-Na-co-St/Fe3O4 composite were observed and analyzed by transmission electron microscopy (TEM). The average Fe3O4 content of PAMPS-Na-co-St/Fe3O4 was determined by thermogravimetric analysis (TGA). The inhibitory action of PAMPS-Na-co-St/Fe3O4 towards steel corrosion in 1 M HCl solutions has been investigated by polarization and electrochemical impedance spectroscopy (EIS) methods. Polarization measurements indicate that PAMPS-Na-co-St/Fe3O4 acts as a mixed type-inhibitor and the inhibition efficiency increases with inhibitor concentration. The results of potentiodynamic polarization and EIS measurements clearly showed that the inhibition mechanism involves blocking of the steel surface by inhibitor molecules via adsorption. PMID:24487568

  5. Synthesis and evaluation of poly(Sodium 2-Acrylamido-2-Methylpropane Sulfonate-co-Styrene)/magnetite nanoparticle composites as corrosion inhibitors for steel.

    PubMed

    El-Mahdy, Gamal A; Atta, Ayman M; Al-Lohedan, Hamad A

    2014-01-30

    Self-stabilized magnetic polymeric composite nanoparticles of coated poly-(sodium 2-acrylamido-2-methylpropane sulfonate-co-styrene)/magnetite (PAMPS-Na-co-St/Fe3O4) were prepared by emulsifier-free miniemulsion polymerization using styrene (St) as a monomer, 2-acrylamido-2-methylpropane sulfonic acid sodium salt (AMPS-Na) as an ionic comonomer, N,N-methylenebisacrylamide (MBA) as crosslinker, hexadecane (HD) as a hydrophobic solvent, and 2,2-azodiisobutyronitrile (AIBN) as an initiator in the presence of hydrophobic oleic acid coated magnetite particles. Hydrophobic oleic acid coated magnetite particles with an average size of about 7-10 nm were prepared with the new modified water-based magnetite ferrofluid, synthesized by a chemical modified coprecipitation method. The morphology and the particle size distributions of the crosslinked PAMPS-Na-co-St/Fe3O4 composite were observed and analyzed by transmission electron microscopy (TEM). The average Fe3O4 content of PAMPS-Na-co-St/Fe3O4 was determined by thermogravimetric analysis (TGA). The inhibitory action of PAMPS-Na-co-St/Fe3O4 towards steel corrosion in 1 M HCl solutions has been investigated by polarization and electrochemical impedance spectroscopy (EIS) methods. Polarization measurements indicate that PAMPS-Na-co-St/Fe3O4 acts as a mixed type-inhibitor and the inhibition efficiency increases with inhibitor concentration. The results of potentiodynamic polarization and EIS measurements clearly showed that the inhibition mechanism involves blocking of the steel surface by inhibitor molecules via adsorption.

  6. Engineered ketol-acid reductoisomerase and alcohol dehydrogenase enable anaerobic 2-methylpropan-1-ol production at theoretical yield in Escherichia coli.

    PubMed

    Bastian, Sabine; Liu, Xiang; Meyerowitz, Joseph T; Snow, Christopher D; Chen, Mike M Y; Arnold, Frances H

    2011-05-01

    2-methylpropan-1-ol (isobutanol) is a leading candidate biofuel for the replacement or supplementation of current fossil fuels. Recent work has demonstrated glucose to isobutanol conversion through a modified amino acid pathway in a recombinant organism. Although anaerobic conditions are required for an economically competitive process, only aerobic isobutanol production has been feasible due to an imbalance in cofactor utilization. Two of the pathway enzymes, ketol-acid reductoisomerase and alcohol dehydrogenase, require nicotinamide dinucleotide phosphate (NADPH); glycolysis, however, produces only nicotinamide dinucleotide (NADH). Here, we compare two solutions to this imbalance problem: (1) over-expression of pyridine nucleotide transhydrogenase PntAB and (2) construction of an NADH-dependent pathway, using engineered enzymes. We demonstrate that an NADH-dependent pathway enables anaerobic isobutanol production at 100% theoretical yield and at higher titer and productivity than both the NADPH-dependent pathway and transhydrogenase over-expressing strain. Our results show how engineering cofactor dependence can overcome a critical obstacle to next-generation biofuel commercialization.

  7. Solubility of n-butane and 2-methylpropane (isobutane) in 1-alkyl-3-methylimidazolium-based ionic liquids with linear and branched alkyl side-chains.

    PubMed

    Pison, Laure; Shimizu, Karina; Tamas, George; Lopes, José Nuno Canongia; Quitevis, Edward L; Gomes, Margarida F Costa

    2015-11-11

    The solubility of n-butane and 2-methylpropane (isobutane) in three ionic liquids - 1-(2-methylpropyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [(2mC3)C1im][Ntf2], 1-(3-methylbutyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [(3mC4)C1im][Ntf2] and 1-methyl-3-pentylimidazolium bis(trifluoromethylsulfonyl)imide [C5C1im][Ntf2] - has been measured at atmospheric pressure from 303 to 343 K. Isobutane is less soluble than n-butane in all the ionic liquids. Henry's constant values range from 13.8 × 10(5) Pa for n-butane in [C5C1im][Ntf2] at 303 K to 64.5 × 10(5) Pa for isobutane in [(2mC3)C1im][Ntf2] at 343 K. The difference in solubility between the two gases can be explained by a more negative enthalpy of solvation for n-butane. A structural analysis of the pure solvents and of the solutions of the gases, probed by molecular dynamics simulations, could explain the differences found in the systems: (i) the nonpolar domains of the ionic liquids accommodate better the long and more flexible n-butane solute; (ii) the small differences in solubility of each gas in the ionic liquids with the same number of carbon atoms in the alkyl side-chains are explained by the absence of large structural differences in the pure solvents. In all cases, the structural analysis of the four ionic liquids confirms that the studied gases can act as probes of the molecular structure of the ionic liquids, the simulations being always compatible with the experimental solubility data.

  8. Solubility of n-butane and 2-methylpropane (isobutane) in 1-alkyl-3-methylimidazolium-based ionic liquids with linear and branched alkyl side-chains.

    PubMed

    Pison, Laure; Shimizu, Karina; Tamas, George; Lopes, José Nuno Canongia; Quitevis, Edward L; Gomes, Margarida F Costa

    2015-11-11

    The solubility of n-butane and 2-methylpropane (isobutane) in three ionic liquids - 1-(2-methylpropyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [(2mC3)C1im][Ntf2], 1-(3-methylbutyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [(3mC4)C1im][Ntf2] and 1-methyl-3-pentylimidazolium bis(trifluoromethylsulfonyl)imide [C5C1im][Ntf2] - has been measured at atmospheric pressure from 303 to 343 K. Isobutane is less soluble than n-butane in all the ionic liquids. Henry's constant values range from 13.8 × 10(5) Pa for n-butane in [C5C1im][Ntf2] at 303 K to 64.5 × 10(5) Pa for isobutane in [(2mC3)C1im][Ntf2] at 343 K. The difference in solubility between the two gases can be explained by a more negative enthalpy of solvation for n-butane. A structural analysis of the pure solvents and of the solutions of the gases, probed by molecular dynamics simulations, could explain the differences found in the systems: (i) the nonpolar domains of the ionic liquids accommodate better the long and more flexible n-butane solute; (ii) the small differences in solubility of each gas in the ionic liquids with the same number of carbon atoms in the alkyl side-chains are explained by the absence of large structural differences in the pure solvents. In all cases, the structural analysis of the four ionic liquids confirms that the studied gases can act as probes of the molecular structure of the ionic liquids, the simulations being always compatible with the experimental solubility data. PMID:26506981

  9. THERMODYNAMIC PROPERTIES HF 298, S 298, AND CP(T) FOR 2-FLUORO-2-METHYLPROPANE, HF 298 OF FLUORINATED ETHANES, AND GROUP ADDITIVITY FOR FLUOROALKANES. (R824970)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  10. Density and viscosity of binary mixtures of ethyl acetate with methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, 2-methylpropan-1-ol, and 2-methylpropan-2-ol at (298.15, 303.15, and 308.15) K

    SciTech Connect

    Nikam, P.S.; Mahale, T.R.; Hasan, M.

    1996-09-01

    Densities and viscosities have been measured for the binary mixtures of ethyl acetate with linear and branched alkanols (C{sub 1}-C{sub 4}) at (298.15, 303.15, and 308.15) K. The experimental density ({zeta}) and viscosity ({eta}) values were used to calculate the excess molar volume (V{sup E}) and viscosity deviation ({Delta}{eta}). The V{sup E} and {Delta}{eta} values have been fitted to a Redlich-Kister polynomial.

  11. Perfusion Imaging with a Freely Diffusible Hyperpolarized Contrast Agent

    PubMed Central

    Grant, Aaron K.; Vinogradov, Elena; Wang, Xiaoen; Lenkinski, Robert E.; Alsop, David C.

    2011-01-01

    Contrast agents that can diffuse freely into or within tissue have numerous attractive features for perfusion imaging. Here we present preliminary data illustrating the suitability of hyperpolarized 13C labeled 2-methylpropan-2-ol (also known as dimethylethanol, tertiary butyl alcohol and tert-butanol) as a freely diffusible contrast agent for magnetic resonance perfusion imaging. Dynamic 13C images acquired in rat brain with a balanced steady-state free precession (bSSFP) sequence following administration of hyperpolarized 2-methylpropan-2-ol show that this agent can be imaged with 2–4s temporal resolution, 2mm slice thickness, and 700 micron in-plane resolution while retaining adequate signal-to-noise ratio. 13C relaxation measurements on 2-methylpropan-2-ol in blood at 9.4T yield T1=46±4s and T2=0.55±0.03s. In the rat brain at 4.7T, analysis of the temporal dynamics of the bSSFP image intensity in tissue and venous blood indicate that 2-methylpropan-2-ol has a T2 of roughly 2–4s and a T1 of 43±24s. In addition, the images indicate that 2-methylpropan-2-ol is freely diffusible in brain and hence has a long residence time in tissue; this in turn makes it possible to image the agent continuously for tens of seconds. These characteristics show that 2-methylpropan-2-ol is a promising agent for robust and quantitative perfusion imaging in the brain and body. PMID:21432901

  12. Rate of Hydrolysis of Tertiary Halogeno Alkanes

    ERIC Educational Resources Information Center

    Pritchard, D. R.

    1978-01-01

    Describes an experiment to measure the relative rate of hydrolysis of the 2-x-2 methylpropanes, where x is bromo, chloro or iodo. The results are plotted on a graph from which the relative rate of hydrolysis can be deduced. (Author/GA)

  13. Well cementing method using an am/amps fluid loss additive blend

    SciTech Connect

    Boncan, V.G.; Gandy, R.

    1986-12-30

    A method is described of cementing a wellbore, comprising the steps of: mixing together a hydraulic cement, water in an amount to produce a pumpable slurry, and a non-retarding fluid loss additive blend. The blend comprises a copolymer of acrylamide and 2-acrylamide-2-methylpropane sulfonate, the sodium salt of naphthalene formaldehyde sulfonate, and polyvinylpyrrolidone polymer; pumping the cement slurry to the desired location in the wellbore; and allowing the cement slurry to harden to a solid mass.

  14. Metabolism of 2-Methylpropene (Isobutylene) by the Aerobic Bacterium Mycobacterium sp. Strain ELW1

    PubMed Central

    Kottegoda, Samanthi; Waligora, Elizabeth

    2015-01-01

    An aerobic bacterium (Mycobacterium sp. strain ELW1) that utilizes 2-methylpropene (isobutylene) as a sole source of carbon and energy was isolated and characterized. Strain ELW1 grew on 2-methylpropene (growth rate = 0.05 h−1) with a yield of 0.38 mg (dry weight) mg 2-methylpropene−1. Strain ELW1 also grew more slowly on both cis- and trans-2-butene but did not grow on any other C2 to C5 straight-chain, branched, or chlorinated alkenes tested. Resting 2-methylpropene-grown cells consumed ethene, propene, and 1-butene without a lag phase. Epoxyethane accumulated as the only detected product of ethene oxidation. Both alkene consumption and epoxyethane production were fully inhibited in cells exposed to 1-octyne, suggesting that alkene oxidation is initiated by an alkyne-sensitive, epoxide-generating monooxygenase. Kinetic analyses indicated that 1,2-epoxy-2-methylpropane is rapidly consumed during 2-methylpropene degradation, while 2-methyl-2-propen-1-ol is not a significant metabolite of 2-methylpropene catabolism. Degradation of 1,2-epoxy-2-methylpropane by 2-methylpropene-grown cells led to the accumulation and further degradation of 2-methyl-1,2-propanediol and 2-hydroxyisobutyrate, two sequential metabolites previously identified in the aerobic microbial metabolism of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA). Growth of strain ELW1 on 2-methylpropene, 1,2-epoxy-2-methylpropane, 2-methyl-1,2-propanediol, and 2-hydroxyisobutyrate was fully inhibited when cobalt ions were omitted from the growth medium, while growth on 3-hydroxybutyrate and other substrates was unaffected by the absence of added cobalt ions. Our results suggest that, like aerobic MTBE- and TBA-metabolizing bacteria, strain ELW1 utilizes a cobalt/cobalamin-dependent mutase to transform 2-hydroxyisobutyrate. Our results have been interpreted in terms of their impact on our understanding of the microbial metabolism of alkenes and ether oxygenates. PMID:25576605

  15. Discovery of novel (4-piperidinyl)-piperazines as potent and orally active acetyl-CoA carboxylase 1/2 non-selective inhibitors: F-Boc and triF-Boc groups are acid-stable bioisosteres for the Boc group.

    PubMed

    Chonan, Tomomichi; Wakasugi, Daisuke; Yamamoto, Daisuke; Yashiro, Miyoko; Oi, Takahiro; Tanaka, Hiroaki; Ohoka-Sugita, Ayumi; Io, Fusayo; Koretsune, Hiroko; Hiratate, Akira

    2011-03-01

    Novel (4-piperidinyl)-piperazine derivatives were synthesized and evaluated as ACC1/2 non-selective inhibitors. Optimization of the substituents on the nitrogen of the piperidine ring led to the identification of the fluorine substituted tert-butoxycarbonyl group. Advanced analog, 1,1,1-trifluoro-2-methylpropan-2-yl 4-{4-[(2-amino-6-methyl-1-benzothiophen-3-yl)carbonyl]piperazin-1-yl}piperidine-1-carboxylate (12c) showed potent inhibitory activities in enzyme-assay and cell-based assays. Compound 12c also exhibited reduction of hepatic de novo fatty acid synthesis in rats after oral administration.

  16. K2CO3-catalyzed synthesis of chromones and 4-quinolones through the cleavage of aromatic C-O bonds.

    PubMed

    Zhao, Jie; Zhao, Yufen; Fu, Hua

    2012-06-01

    Phenol-derived electrophiles are favorable substrates because phenols are naturally abundant or can be readily prepared from other aromatic compounds. However, the cleavage of aromatic C-O bonds is a great challenge because of their high energy. K(2)CO(3)-catalyzed intramolecular cyclization of 1-(2-alkoxyphenyl)-3-akylpropane-1,3-dione and 3-(alkylimino)-1-(2-methoxyphenyl)-2-methylpropan-1-one derivatives via the selective cleavage of aromatic C-O bonds is reported. The corresponding chromone and 4-quinolone derivatives were obtained in reasonable yields. PMID:22587645

  17. Well treating fluids and additives therefor

    SciTech Connect

    Patel, B.

    1991-07-16

    This patent describes a solid, dry additive for reducing the water loss and improving other properties of well treating fluids in high temperature environments. It comprises a mixture of a water soluble copolymer of N-vinyl pyrrolidone and the sodium salt of 2- acrylamido-2-methylpropane sulfonic acid and an organic compound selected from the group consisting of lignites, tannins, asphaltic materials, derivatives thereof and mixtures of such compounds, the mixture of the water soluble copolymer and organic compound being prepared by mixing a water and oil emulsion containing the copolymer with the organic compound followed by removing the oil and water from the resultant mixture.

  18. Structure-Guided Engineering of Lactococcus lactis Alcohol Dehydrogenase LlAdhA for Improved Conversion of Isobutyraldehyde to Isobutanol

    PubMed Central

    Liu, Xiang; Bastian, Sabine; Snow, Christopher D.; Brustad, Eric M.; Saleski, Tatyana E.; Xu, Jian-He; Meinhold, Peter; Arnold, Frances H.

    2012-01-01

    We have determined the X-ray crystal structures of the NADH-dependent alcohol dehydrogenase LlAdhA from Lactococcus lactis and its laboratory-evolved variant LlAdhARE1 at 1.9 Å and 2.5 Å resolution, respectively. LlAdhARE1, which contains three amino acid mutations (Y50F, I212T, and L264V), was engineered to increase the microbial production of isobutanol (2-methylpropan-1-ol) from isobutyraldehyde (2-methylpropanal). Structural comparison of LlAdhA and LlAdhARE1 indicates that the enhanced activity on isobutyraldehyde stems from increases in the protein’s active site size, hydrophobicity, and substrate access. Further structure-guided mutagenesis generated a quadruple mutant (Y50F/N110S/I212T/L264V), whose KM for isobutyraldehyde is ~17-fold lower and catalytic efficiency (kcat/KM) is ~160-fold higher than wild-type LlAdhA. Combining detailed structural information and directed evolution, we have achieved significant improvements in non-native alcohol dehydrogenase activity that will facilitate the production of next-generation fuels such as isobutanol from renewable resources. PMID:22974724

  19. Use of amidoximated hydrogel for removal and recovery of U(VI) ion from water samples.

    PubMed

    Hazer, Orhan; Kartal, Senol

    2010-10-15

    Poly(acrylamidoxime-co-2-acrylamido-2-methylpropane sulfonic acid) (PAMSA) hydrogel was prepared by copolymerization of acrylonitrile and 2-acrylamido-2-methylpropane sulfonic acid as monomer, N,N'-methylenebis(acrylamide) as crosslinking agent and potassium peroxodisulfate as initiator. Amidoximated copolymer network was prepared by the reaction of copolymer network with hydroxylamine hydrochloride. A batch procedure was used for the determination of the characteristics of the U(VI) solid phase extraction from the amidoximated hydrogel. The determination of U(VI) was performed by spectrophotometric method using arsenazo-III as complexing agent. Optimal pH value for the quantitative preconcentration was 3, and full desorption was achieved with 3 mol L(-1) HClO(4). The adsorption process can be well described by the pseudo-second-order kinetic model, and the equilibrium adsorption isotherm was closely fitted with the Langmuir model. A preconcentration factor of 20 and the three sigma detection limit of 2.8 μg L(-1) (n=20) were achieved for uranium(VI) ions. The PAMSA hydrogel was used for separating and preconcentrating the uranyl ion existing in sea water samples, thermal spring water samples and the certified reference materials (TMDA 64; fortified lake water sample). PMID:20875604

  20. Amino-functionalized (meth)acryl polymers by use of a solvent-polarity sensitive protecting group (Br-t-BOC)

    PubMed Central

    Tabatabai, Monir; Herrmann, Markus

    2016-01-01

    Summary We describe the synthesis of bromo-tert-butyloxycarbonyl (Br-t-BOC)-amino-protected monomers 2-((1-bromo-2-methylpropan-2-yl)oxycarbonylamino)ethyl (meth)acrylate 3a,b. For this purpose, 2-isocyanatoethyl (meth)acrylate 1a,b was reacted with 1-bromo-2-methylpropan-2-ol (2a). The free radical polymerization of (Br-t-BOC)-aminoethyl (meth)acrylates 3a,b yielded poly((Br-t-BOC)-aminoethyl (meth)acrylate) 6a,b bearing protected amino side groups. The subsequent solvolysis of the Br-t-BOC function led to the new polymers poly(2-aminoethyl (meth)acrylate) 8a,b with protonated free amino groups. The monomers and the resulting polymers were thoroughly characterized by 1H NMR, IR, GPC and DSC methods. The kinetics of the deprotection step was followed by 1H NMR spectroscopy. The solvent polarity and neighboring group effects on the kinetics of deprotection are discussed. PMID:26977183

  1. Solvent effects on kinetics of an heteroatomic nucleophilic substitution reaction in ionic liquid and molecular solvents mixtures

    NASA Astrophysics Data System (ADS)

    Salari, Hadi; Pedervand, Mohsen; Sadeghzadeh-Darabi, Faramarz; Gholami, Mohammad Reza

    2013-12-01

    Rate constants, k A, for the aromatic nucleophilic substitution reaction of 2-chloro-3,5-dinitropyridine with aniline were determined in different compositions of 2-propanol mixed with hexane, benzene, and 2-methylpropan-2-ol and 1-ethyl-3-methylimidazolium ethylsulfate ([Emim][EtSO4]) with dimethyl sulfoxide at 25°C. The obtained rate constants of the reaction in pure solvents are in the following order: 2-methylpropan-2-ol > dimethyl sulfoxide > 2-propanol > hexane > benzene > [Emim][EtSO4]. Molecularmicroscopic solvent parameters corresponding to the selected binary mixtures were utilized to study the kinetics of a nucleophilic substitution reaction in order to investigate and compare the effects of the solvents on a chemical process. The influence of solvent parameters including normalized polarity ( E {/T N }), dipolarity/polarizability (π*), hydrogen bond donor acidity (α), and hydrogen bond acceptor basicity (β) on the second-order rate constants were investigated and multiple linear regressions gave much better results with regard to single parameter regressions. The dipolarity/polarizability of media has a positive effect in all mixtures regarding zwitterionic character of the reaction intermediate and the hydrogen bond acceptor basicity of the solvent by stabilizing of activated complex increases the reaction rate.

  2. Identification and characterization of the aroma-impact components of Thai fish sauce.

    PubMed

    Lapsongphon, Nawaporn; Yongsawatdigul, Jirawat; Cadwallader, Keith R

    2015-03-18

    Comprehensive analysis of the potent odorants in Thai premium fish sauce samples was accomplished by use of complementary volatile isolation methods combined with gas chromatography-olfactometry (GC-O) and GC-mass spectrometry. Odorants of intermediate and low volatility were determined by direct solvent extraction/solvent-assisted flavor evaporation (DSE-SAFE) and aroma extract dilution analysis (AEDA). Meanwhile, static headspace dilution analysis (SHDA) and headspace solid-phase microextraction (H-SPME) were used to determine the highly volatile odorants. Results of AEDA indicated the importance (log3FD factor≥6) of five acidic odorants (butanoic acid, 3-methylbutanoic acid, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 4-hydroxy-2-ethyl-5-methyl-3(2H)-furanone, and 2-phenylacetic acid) and four neutral/basic odorants (3-methylbutanal, (Z)-1,5-octadien-3-one, phenylacetaldehyde, and o-aminoacetophone). Results of SHDA indicated the predominant (log3FD factors≥5) headspace odorants were methanethiol, 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, dimethyl trisulfide, 3-(methylthio)propanal, and butanoic acid. Concentrations for 21 odorants were determined by stable isotope dilution analysis (SIDA), and their odor-activity values (OAVs) were calculated. Among these, methanethiol, 2-methylpropanal, 3-methylbutanal, dimethyl trisulfide, 3-(methylthio)propanal, and butanoic acid had the highest OAVs (>500). Results of aroma recombination and omission studies revealed the importance of acids, aldehydes, and sulfur-containing compounds to the overall aroma of the Thai fish sauce. PMID:25730550

  3. Amino-functionalized (meth)acryl polymers by use of a solvent-polarity sensitive protecting group (Br-t-BOC).

    PubMed

    Ritter, Helmut; Tabatabai, Monir; Herrmann, Markus

    2016-01-01

    We describe the synthesis of bromo-tert-butyloxycarbonyl (Br-t-BOC)-amino-protected monomers 2-((1-bromo-2-methylpropan-2-yl)oxycarbonylamino)ethyl (meth)acrylate 3a,b. For this purpose, 2-isocyanatoethyl (meth)acrylate 1a,b was reacted with 1-bromo-2-methylpropan-2-ol (2a). The free radical polymerization of (Br-t-BOC)-aminoethyl (meth)acrylates 3a,b yielded poly((Br-t-BOC)-aminoethyl (meth)acrylate) 6a,b bearing protected amino side groups. The subsequent solvolysis of the Br-t-BOC function led to the new polymers poly(2-aminoethyl (meth)acrylate) 8a,b with protonated free amino groups. The monomers and the resulting polymers were thoroughly characterized by (1)H NMR, IR, GPC and DSC methods. The kinetics of the deprotection step was followed by (1)H NMR spectroscopy. The solvent polarity and neighboring group effects on the kinetics of deprotection are discussed. PMID:26977183

  4. Polyprenylated Phloroglucinols from Hypericum maculatum.

    PubMed

    Nedialkov, Paraskev T; Momekov, Georgi; Kokanova-Nedialkova, Zlatina K; Heilmann, Jörg

    2015-07-01

    A detailed phytochemical investigation of the dichloromethane extract of the aerial parts of Hypericum maculatum Crantz. led to the isolation of four new (2-5) and six known (1a/b, 6-10) polyprenylated phloroglucinol derivatives. The new compounds were identified by means of spectral methods (MS, NMR, IR, UV) as (E)-4-(3,7-dimethylocta-2,6-dien-1-yl)-5-hydroxy-2-(3-methylbut-2-en-1-yl)-3,6-dioxocyclohexa-1,4-dien-1-yl isobutyrate (2), (E)-2-(3,7-dimethylocta-2,6-dien-1-yl)-5-hydroxy-4-(3-methylbut-2-en-1-yl)-3,6-dioxocyclohexa-1,4-dien-1-yl isobutyrate (3), (E)-4-(3,7-dimethylocta-2,6-dien-1-yl)-5-hydroxy-2-(3-methylbut-2-en-1-yl)-3,6-dioxocyclohexa-1,4-dien-1-yl 2-methylbutanoate (4) and (E)-2-(3,7-dimethylocta-2,6-dien-1-yl)-5-hydroxy-4-(3-methylbut-2-en-1-yl)-3,6-dioxocyclohexa-1,4-dien-1-yl 2-methylbutanoate (5). The known compounds have been identified as hyperpolyphyllirin/hyperibine J (1a/b), erectquione A (6), (E)-1-(3-(3,7-dimethylocta-2,6-dien--yl)-2,4,6-trihydroxyphenyl)-2-methylpropan-1-one (7), (E)-1-(3-(3,7-dimethylocta-2,6-dien-1-yl)- 2,4,6-trihydroxyphenyl)-2-methylbutan-1-one (8), 1-(5,7-dihydroxy-2-methyl-2-(4-methylpent-3-en-1-yl)chroman-8-yl)-2-methylpropan-1-one (9) and 1-(6,8-dihydroxy-1,1,4a-trimethyl-2,3,4,4a,9,9a-hexahydro-1H-xanthen-5-yl)-2-methylpropan-1-one (10). The stereochemistry of 1a is described for the first time. The cytotoxicity of 1-6 on SKW-3, BV-173 and K-562 tumor cell lines was determined using MTT based assays. PMID:26411018

  5. Solubility of anthracene in binary alkane + methyl tert-butyl ether solvent mixtures at 298.15 K

    SciTech Connect

    McHale, M.E.R.; Kauppila, A.S.M.; Acree, W.E. Jr.

    1996-09-01

    Experimental solubilities are reported for anthracene dissolved in seven binary mixtures containing methyl tert-butyl ether (also called 2-methoxy-2-methylpropane) with hexane, heptane, octane, cyclohexane, methylcyclohexane, 2,2,4-trimethylpentane, and tert-butylcyclohexane (also called (1,1-dimethylethyl)-cyclohexane) at 25 C. Results of these measurements are used to test two mathematical representations based upon the combined nearly ideal binary solvent (NIBS)/Redlich-Kister equation and modified Wilson model. For the seven systems studied, both equations were found to provide an accurate mathematical representation of the experimental data, with an overall average absolute deviation between measured and calculated values being on the order of 0.5%.

  6. The separation and analysis of symmetric and asymmetric dimethylarginine and other hydrophilic isobaric compounds using aqueous normal phase chromatography.

    PubMed

    Pesek, Joseph J; Matyksa, Maria T; Modereger, Brent; Hasbun, Alejandra; Phan, Vy T; Mehr, Zahra; Guzman, Mariano; Watanable, Seiichiro

    2016-04-01

    Two biologically important compounds with clinical relevance, asymmetric dimethylarginine and symmetric dimethylarginine, are analyzed using aqueous normal phase chromatography on silica hydride-based columns. Two different stationary phases were tested, a commercially available Diamond Hydride™ and a 2-acrylamido-2-methylpropane sulfonic acid experimental column. Two types of analytical protocols were investigated: analysis of the compounds when separation was achieved and analysis of the compounds with partial chromatographic separation. Urine samples from tuberculosis patients were tested for levels of asymmetric and symmetric dimethylarginine. The mass spectrometric technique of in-source fragmentation that can provide data similar to a tandem mass analyzer was evaluated as a means of identification and quantitation of the two compounds when complete separation is not achieved. This same protocol was also evaluated for two other isobaric compounds, glucose-1 and glucose-6 phohsphate, and leucine and isoleucine.

  7. Producing Radical-Free Hyperpolarized Perfusion Agents for In Vivo Magnetic Resonance Using Spin-Labeled Thermoresponsive Hydrogel.

    PubMed

    Cheng, Tian; Mishkovsky, Mor; Junk, Matthias J N; Münnemann, Kerstin; Comment, Arnaud

    2016-07-01

    Dissolution dynamic nuclear polarization (DNP) provides a way to tremendously improve the sensitivity of nuclear magnetic resonance experiments. Once the spins are hyperpolarized by dissolution DNP, the radicals used as polarizing agents become undesirable since their presence is an additional source of nuclear spin relaxation and their toxicity might be an issue. This study demonstrates the feasibility of preparing a hyperpolarized [1-(13) C]2-methylpropan-2-ol (tert-butanol) solution free of persistent radicals by using spin-labeled thermoresponsive hydrophilic polymer networks as polarizing agents. The hyperpolarized (13) C signal can be detected for up to 5 min before the spins fully relax to their thermal equilibrium. This approach extends the applicability of spin-labeled thermoresponsive hydrogel to the dissolution DNP field and highlights its potential as polarizing agent for preparing neat slowly relaxing contrast agents. The hydrogels are especially suited to hyperpolarize deuterated alcohols which can be used for in vivo perfusion imaging. PMID:27184565

  8. Cell proliferation and cell sheet detachment from the positively and negatively charged nanocomposite hydrogels.

    PubMed

    Liu, Dan; Wang, Tao; Liu, Xinxing; Tong, Zhen

    2014-01-01

    The charged nanocomposite hydrogels (NC gels) were synthesized by copolymerization of positively or negatively chargeable monomer with N-isopropylacrylamide (NIPAm) in the aqueous suspension of hectorite clay. The ionic NC gels preserved the thermo-responsibility with the phase-transition temperature below 37°C. The L929 cell proliferation was sensitive to charge polarity and charge density. As compared to the PNIPAm NC gel, the cationic NC gels with <5 mol % of 2-(dimethylamino)ethyl methacrylate (DMAEMA) showed improved cell proliferation, whereas the cells grew slowly on the gels with negatively charged 2-acrylamido-2-methylpropane sulfonic acid (AMPSNa). By lowering temperature, rapid cell sheet detachment was observed from the surface of ionic NC gels with 1 mol % of ionizable monomers. However, lager amount of AMPSNa or DMAEMA did not support rapid cell sheet detachment, probably owing to the adverse swelling effects and/or enhanced electrostatic attraction.

  9. Thermodynamic and acoustical properties of mixtures p-anisaldehyde—alkanols (C1-C4)—2-methyl-1-propanol at 303.15 K

    NASA Astrophysics Data System (ADS)

    Saini, Balwinder; Kumar, Ashwani; Rani, Ruby; Bamezai, Rajinder K.

    2016-07-01

    The density, viscosity and speed of sound of pure p-anisaldehyde and some alkanols, for example, methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol, 2-methylpropan-1-ol, and the binary mixtures of p-anisaldehyde with these alkanols were measured over the entire composition range at 303.15 K. From the experimental data, various thermodynamic parameters such as excess molar volume ( V E), excess Gibbs free energy of activation (Δ G*E), and deviation parameters like viscosity (Δη), speed of sound (Δ u), isentropic compressibility (Δκs), are calculated. The excess as well as deviation parameters are fitted to Redlich—Kister equation. Additionally, the viscosity data for the systems has been used to correlate the application of empirical relation given by Grunberg and Nissan, Katti and Chaudhari, and Hind et al. The results are discussed in terms of specific interactions present in the mixtures.

  10. Fluorinated Alkoxide-Based Magnesium-Ion Battery Electrolytes that Demonstrate Li-Ion-Battery-Like High Anodic Stability and Solution Conductivity.

    PubMed

    Crowe, Adam J; Stringham, Kyle K; Bartlett, Bart M

    2016-09-01

    Based on DFT predictions, a series of highly soluble fluorinated alkoxide-based electrolytes were prepared, examined electrochemically, and reversibly cycled. The alcohols react with ethylmagnesium chloride to generate a fluoroalkoxy-magnesium chloride intermediate, which subsequently reacts with aluminum chloride to generate the electrolyte. Solutions starting from a 1,1,1,3,3,3-hexafluoro-2-methylpropan-2-ol precursor exhibit high anodic stability, 3.2 V vs Mg(2+/0), and a record 3.5 mS/cm solution conductivity. Excellent galvanostatic cycling and capacity retention (94%) is observed with more than 300 h of cycle time while employing the standard Chevrel phase-Mo6S8 cathode material.

  11. Electrochromic cells with lutetium diphthalocyanine and semisolid polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Pizzarello, F. A.; Nicholson, M. M.

    1987-11-01

    Cyclic voltammograms were obtained for lutetium diphthalocyanine films in contact with plasticized poly(ethylene oxide) (PEO) electrolytes or solvent-swollen 2-acrylamido-2-methylpropane- sulfonic acid (AMPS) polymer electrolytes. Cells containing PEO-salt combinations plasticized with propylene glycol (PG) or acetonitrile resulted in slow, nonuniform color changes due to high interfacial resistance. The AMPS cell fabrication was simplified by starting with a commercial AMPS polymer product in the form of a transparent sheet containing water and other additives. This material, when further swollen in a PG-HC1 solution, produced the full range of uniform colors, accompanied by well defined voltammograms. It maintained good contact with the dye from -5 to 40 C.

  12. Separation of PCR-ready DNA from dairy products using magnetic hydrophilic microspheres and poly(ethylene glycol)-NaCl water solutions

    NASA Astrophysics Data System (ADS)

    Rittich, Bohuslav; Španová, Alena; Šálek, Petr; Němcová, Petra; Trachtová, Štěpánka; Horák, Daniel

    2009-05-01

    Carboxyl group-containing magnetic nonporous poly(2-hydroxyethyl methacrylate- co-glycidyl methacrylate) (P(HEMA- co-GMA)) and magnetic glass microspheres were used for the isolation of bacterial DNA. P(HEMA- co-GMA) microspheres were prepared by the dispersion polymerization in toluene/2-methylpropan-1-ol mixture in the presence of magnetite nanoparticles obtained by coprecipitation of Fe(II) and Fe(III) salts with ammonium hydroxide. Carboxyl groups were then introduced by oxidation of the microspheres with potassium permanganate. The most extensive DNA recovery was achieved at PEG 6000 concentrations of 12% or 16% and 2 M NaCl. The method proposed was used for bacterial DNA isolation from different dairy products containing Bifidobacterium and Lactobacillus cells. The presence of target DNA and the quality of isolated DNA were checked by polymerase chain reaction (PCR) amplification with specific primers.

  13. The separation and analysis of symmetric and asymmetric dimethylarginine and other hydrophilic isobaric compounds using aqueous normal phase chromatography.

    PubMed

    Pesek, Joseph J; Matyksa, Maria T; Modereger, Brent; Hasbun, Alejandra; Phan, Vy T; Mehr, Zahra; Guzman, Mariano; Watanable, Seiichiro

    2016-04-01

    Two biologically important compounds with clinical relevance, asymmetric dimethylarginine and symmetric dimethylarginine, are analyzed using aqueous normal phase chromatography on silica hydride-based columns. Two different stationary phases were tested, a commercially available Diamond Hydride™ and a 2-acrylamido-2-methylpropane sulfonic acid experimental column. Two types of analytical protocols were investigated: analysis of the compounds when separation was achieved and analysis of the compounds with partial chromatographic separation. Urine samples from tuberculosis patients were tested for levels of asymmetric and symmetric dimethylarginine. The mass spectrometric technique of in-source fragmentation that can provide data similar to a tandem mass analyzer was evaluated as a means of identification and quantitation of the two compounds when complete separation is not achieved. This same protocol was also evaluated for two other isobaric compounds, glucose-1 and glucose-6 phohsphate, and leucine and isoleucine. PMID:26952368

  14. Characterization of the most odor-active compounds of Iberian ham headspace.

    PubMed

    Carrapiso, Ana I; Ventanas, Jesús; García, Carmen

    2002-03-27

    Gas chromatography-olfactometry (GC-O) based on detection frequency (DF) was used to characterize the most odor-active compounds from the headspace of Iberian ham. Twenty-eight odorants were identified by GC-O on two capillary columns, including aldehydes (11), sulfur-containing compounds (7), ketones (5), nitrogen-containing compounds (2), esters (2), and an alcohol. Among them, the highest odor potencies (DF values) were found for 2-methyl-3-furanthiol, 2-heptanone, 3-methylbutanal, methanethiol, hexanal, hydrogen sulfide, 1-penten-3-one, 2-methylpropanal, ethyl 2-methylbutyrate, and (E)-2-hexenal. Nine of the 28 most odor-active compounds were identified for the first time as aroma components of dry-cured ham, including hydrogen sulfide, 1-penten-3-one, (Z)-3-hexenal, 1-octen-3-one, and the meaty-smelling compounds 2-methyl-3-furanthiol, 2-furfurylthiol, 3-mercapto-2-pentanone, 2-acetyl-1-pyrroline, and 2-propionyl-1-pyrroline.

  15. Crystal structures of 6-[(2-hydroxy-1,1-bishydroxymethylethylamino)methylene]-2, 4-dinitrocyclohexa-2, 4-dienone hydrate and complexes of copper(II) chloride and copper(II) nitrate with this ligand

    SciTech Connect

    Chumakov, Yu. M. Tsapkov, V. I.; Jeanneau, E.; Bocelli, G.; Luneau, D.

    2006-07-15

    The crystal structures of 6-[(2-hydroxy-1,1-bishydroxymethylethylamino)methylene]-2, 4-dinitrocyclohexa-2, 4-dienone hydrate L . H{sub 2}O (I), chloro-(2-hydroxymethyl-2-methylpropane-1,3-diol-2-iminomethyl-4, 6-dinitrophenolo)aquacopper hydrate [Cu(H{sub 2}O)(L-H)Cl] . H{sub 2}O (II), and (2-hydroxymethyl-2-methylpropane-1,3-diol-2-iminomethyl-4,6-dinitrophenolo) aquacopper nitrate [Cu(H{sub 2}O)(L-H)]NO{sub 3} (III) are determined using X-ray diffraction. It is established that the salicylidene fragment of azomethine L in the structure of compound I is in a quinoid tautomeric form. In the crystal, molecules L and water molecules are joined together by hydrogen bonds into two-dimensional layers aligned parallel to the (010) plane. The copper atom in the structure of compound II coordinates the singly deprotonated tridentate molecule L (whose salicylidene fragment is in a benzenoid form), the chlorine ion, and the water molecule. The coordination polyhedron of the central copper atom is a distorted tetragonal pyramid. In the structure of compound III, the polymer chains are formed through the coordination bonds of the copper atom with two oxygen atoms of the amino alcohol fragment of azomethine L of the neighboring complex, which is related to the initial complex by the translation along the x axis. The coordination polyhedron of the central atom is an elongated tetragonal bipyramid. Polymers and nitro groups form a three-dimensional framework through hydrogen bonds.

  16. Phase equilibrium of binary mixtures of cyclic ethers + chlorobutane isomers: experimental measurements and SAFT-VR modeling.

    PubMed

    Giner, Beatriz; Gascón, Ignacio; Artigas, Héctor; Lafuente, Carlos; Galindo, Amparo

    2007-08-16

    The phase equilibria (experimental and modeled) of eight binary mixtures each formed by a cyclic ether (1,3-dioxolane or 1,4-dioxane) and a chlorobutane isomer (1-chlorobutane, 2-chlorobutane, 1-chloro-2-methylpropane, or 2-chloro-2-methylpropane) are presented. New experimental vapor-liquid equilibrium data at isothermal conditions (298.15, 313.15, and 328.15 K) has been obtained, and the statistical associating fluid theory for potentials of variable range (SAFT-VR) is used to model the mixtures. The results are discussed in terms of both the molecular characteristics of the pure compounds and the unlike intermolecular interactions present in the mixtures. The SAFT-VR approach is first used together with standard combining rules without adjustable parameters in order to predict the phase behavior at isothermal conditions. Good agreement between experiment and the prediction is found with such a model. Mean absolute deviations for pressures lie between 1 and 3 kPa, while for vapor phase compositions are less than 0.03 in mole fraction. However, a better agreement, can be obtained by introducing one adjustable parameter kij, which modifies the strength of the dispersion interaction between unlike components in the mixtures. This parameter is adjusted so as to model the phase equilibrium of the whole family of mixtures studied here at isothermal and isobaric conditions. We find that a unique unlike parameter kij is valid for all the studied mixtures and it is not temperature or pressure dependent. This unique transferable parameter together with the SAFT-VR approach provide a description of the vapor-liquid equilibrium of the mixtures that is in excellent agreement with the experimental data. In this case, the absolute deviations are of the order of 0.001 in mole fraction for vapor-phase compositions and less than 1 kPa for pressure.

  17. Volatiles released from bean plants in response to agromyzid flies.

    PubMed

    Wei, Jia-Ning; Zhu, Junwei; Kang, Le

    2006-07-01

    Liriomyza sativae Blanchard and Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae) are two invasive flies in China that have caused economical damage on vegetables and ornamental plants. In this article, we report the profiles of emitted volatiles from healthy, mechanically damaged, and leafminer-damaged bean, Phaseolus vulgaris L., plants. Among 25 emitted volatiles identified, (E)-2-hexen-1-al, (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), (Z)-3-hexenyl acetate, (Z)-3-hexen-1-ol, (syn)- and (anti)-2-methylpropanal oxime, (syn)-2-methylbutanal oxime, linalool, and (E,E)-alpha-farnesene were consistently released from damaged bean plants. Combined amounts of these nine compounds made up more than 70% of the total volatiles emitted from each treatment. No qualitative differences in volatile emission were found between bean plants damaged by the two fly species; however, amounts of several major compounds induced by L. huidobrensis damage were significantly higher than those from plants damaged by L. sativae. The mechanically damaged plants released a higher proportion of green leaf volatiles than plants in the other treatments, whereas leafminer-damaged plants produced more terpenoids and oximes. Furthermore, the volatile profiles emitted from plants, damaged by adult leafminers, by second instar larvae, and even the plants with empty mines left by leafminer larvae (the pupal stage) were significantly different. The identification of volatile oximes released from damaged plants was confirmed and is discussed in a behavioral and biological control context.

  18. Redox Potentials, Laccase Oxidation, and Antilarval Activities of Substituted Phenols

    PubMed Central

    Prasain, Keshar; Nguyen, Thi D. T.; Gorman, Maureen J.; Barrigan, Lydia M.; Peng, Zeyu; Kanost, Michael R.; Syed, Lateef U.; Li, Jun; Zhu, Kun Yan; Hua, Duy H.

    2012-01-01

    Laccases are copper-containing oxidases that are involved in sclerotization of the cuticle of mosquitoes and other insects. Oxidation of exogenous compounds by insect laccases may have the potential to produce reactive species toxic to insects. We investigated two classes of substituted phenolic compounds, halogenated di- and trihydroxybenzenes and substituted di-tert-butylphenols, on redox potential, oxidation by laccase and effects on mosquito larval growth. An inverse correlation between the oxidation potentials and laccase activity of halogenated hydroxybenzenes was found. Substituted di-tert-butylphenols however were found to impact mosquito larval growth and survival. In particular, 2,4-di-tert-butyl-6-(3-methyl-2-butenyl)phenol (15) caused greater than 98% mortality of Anopheles gambiae larvae in a concentration of 180 nM, whereas 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-methylpropanal oxime (13) and 6,8-di-tert-butyl-2,2-dimethyl-3,4-dihydro-2H-chromene (33) caused 93% and 92% mortalities in concentrations of 3.4 and 3.7 μM, respectively. Larvae treated with di-tert-butylphenolic compounds died just before pupation. PMID:22300888

  19. Correlations of Henry's Law Gas-Solid Virial Coefficients and Chromatographic Retention Times for Hydrocarbons and Halocarbons Adsorbed on Carbopack C Carbon.

    PubMed

    Rybolt; Logan; Milburn; Thomas; Waters

    1999-12-01

    Second gas-solid virial coefficients were determined at 403.5 +/- 0.5 K for 6 adsorbates, including butane, chloroform, trichlorofluoromethane (Freon 11), bromochloromethane, 1-chloro-2-methylpropane, and dibromodifluoromethane. For another 11 adsorbates, including dichlorodifluoromethane (Freon 12), chlorodifluoromethane (Freon 22), methyl chloride, methylene chloride, propane, n-pentane, n-hexane, carbon tetrachloride, 1,2-dichloropropane, butyl chloride, and cyclohexane, B(2s) was measured over a range of temperatures between 308 and 494 K. These values were found using gas-solid chromatography with Carbopack C (Supelco Inc.), a graphitized carbon black powder, as the adsorbent. We find that both the ln B(2s) values and the gas-solid interaction energies are effectively correlated with adsorbate-calculated molar refractivity, r(2) = 0.947 and r(2) = 0.964, respectively. Dipole moment alone provides a nearly random correlation of ln B(2s) and, if used with molar refractivity, gives r(2) = 0.970 for the 17 hydrocarbon and alkyl halide (halocarbon) adsorbates. A theoretical equation was developed that predicts a quantitative structure retention relationship (QSRR) used to correlate ln B(2s) values with molar refractivity. B(2s) values are directly proportional to the retention times of the adsorbates. Using one-surface and two-surface models, a calculation of the surface area of the Carbopack C for each of the 17 adsorbates provided a check on the consistency of the analysis as the adsorbate was varied. Copyright 1999 Academic Press.

  20. Adsorption energies for a nanoporous carbon from gas-solid chromatography and molecular mechanics.

    PubMed

    Rybolt, Thomas R; Ziegler, Katherine A; Thomas, Howard E; Boyd, Jennifer L; Ridgeway, Mark E

    2006-04-01

    Gas-solid chromatography was used to obtain second gas-solid virial coefficients, B2s, in the temperature range 342-613 K for methane, ethane, propane, butane, 2-methylpropane, chloromethane, chlorodifluoromethane, dichloromethane, and dichlorodifluoromethane. The adsorbent used was Carbosieve S-III (Supelco), a carbon powder with fairly uniform, predominately 0.55 nm slit width pores and a N2 BET surface area of 995 m2/g. The temperature dependence of B2s was used to determine experimental values of the gas-solid interaction energy, E*, for each of these molecular adsorbates. MM2 and MM3 molecular mechanics calculations were used to determine the gas-solid interaction energy, E*(cal), for each of the molecules on various flat and nanoporous model surfaces. The flat model consisted of three parallel graphene layers with each graphene layer containing 127 interconnected benzene rings. The nanoporous model consisted of two sets of three parallel graphene layers adjacent to one another but separated to represent the pore diameter. A variety of calculated adsorption energies, E*(cal), were compared and correlated to the experimental E* values. It was determined that simple molecular mechanics could be used to calculate an attraction energy parameter between an adsorbed molecule and the carbon surface. The best correlation between the E*(cal) and E* values was provided by a 0.50 nm nanoporous model using MM2 parameters.

  1. Comparison of Aroma-Active Volatiles in Oolong Tea Infusions Using GC-Olfactometry, GC-FPD, and GC-MS.

    PubMed

    Zhu, JianCai; Chen, Feng; Wang, LingYing; Niu, YunWei; Yu, Dan; Shu, Chang; Chen, HeXing; Wang, HongLin; Xiao, ZuoBing

    2015-09-01

    The aroma profile of oolong tea infusions (Dongdingwulong, DDWL; Tieguanyin, TGY; Dahongpao, DHP) were investigated in this study. Gas chromatography-olfactometry (GC-O) with the method of aroma intensity (AI) was employed to investigate the aroma-active compounds in tea infusions. The results presented forty-three, forty-five, and forty-eight aroma-active compounds in the TGY, DHP, and DDWL infusions, including six, seven, and five sulfur compounds, respectively. In addition, the concentration of volatile compounds in the tea infusions was further quantitated by solid phase microextraction-gas chromatography (SPME)-GC-MS and SPME-GC-flame photometric detection (FPD). Totally, seventy-six and thirteen volatile and sulfur compounds were detected in three types of tea infusions, respectively. Quantitative results showed that forty-seven aroma compounds were at concentrations higher than their corresponding odor thresholds. On the basis of the odor activity values (OAVs), 2-methylpropanal (OAV: 230-455), 3-methylbutanal (1-353), 2-methylbutanal (34-68), nerolidol (108-184), (E)-2-heptenal (148-294), hexanal (134-230), octanal (28-131), β-damascenone (29-59), indole (96-138), 6-methyl-5-hepten-2-one (34-67), (R)-(-)-linalool (63-87), and dimethyl sulfide (7-1320) presented relatively higher OAVs than those of other compounds, indicating the importance of these compounds in the overall aroma of tea infusions.

  2. Second vital coefficients of aqueous alcohols at elevated temperatures: A calorimetric study

    SciTech Connect

    Archer, D.G. )

    1989-06-29

    Enthalpies of dilution of cyclohexanol (aq) to 448 K and of myo-inositol (aq) and of cyclohexanol + myo-inositol (aq) to 398 K are reported. These results, along with enthalpies of dilution for 1-butanol (aq) to 448 K and for 2-methyl-2-propanol (aq) to 423 K, were combined with freezing point depression measurements and ambient-temperature enthalpy of dilution and heat capacity measurements in order to provide the excess Gibbs energy for the aqueous solutes from 273 to 523 K. These excess Gibbs energies were then used to provide parameters for an additivity scheme that permits an approximation of the excess Gibbs energy, and thus the solute and solvent activity coefficients, for dilute aqueous alcohols for which high-temperature data do not exist. These excess Gibbs energies were also used to estimate the aqueous-solution second virial coefficients of the alcohols and of cyclohexane (aq), 1-butane (aq), and 2-methylpropane (aq) in the McMillan-Mayer convention. These virial coefficients for the aqueous hydrocarbons, when compared to gas-phase virial coefficients for the hydrocarbons, suggest that the effect of low-temperature (298 K) water is to lessen the pairwise attraction of aqueous hydrocarbon over that found in the gas phase at the same temperature and that this lessening of the pairwise attraction diminishes at higher temperatures.

  3. Determination of compounds responsible for tempeh aroma.

    PubMed

    Jeleń, Henryk; Majcher, Małgorzata; Ginja, Alexandra; Kuligowski, Maciej

    2013-11-01

    Tempeh is a fermented food, popular mainly in south-east Asia, but also among vegetarians worldwide. It is produced by fermenting soybean or other beans with Rhizopus strains and usually eaten deep-fried, steamed or roasted. The flavour of tempeh depends upon the fermentation time, beans used and the (eventual) frying process. Our goal was to identify compounds responsible for the unique aroma of fermented and fried soy tempeh. Gas chromatography-olfactometry (GC-O) with the aroma extract dilution analysis (AEDA) approach, was used to determine key odorants after 1 and 5 days of fermentation and subsequent frying. Comprehensive gas chromatography-mass spectrometry (GC×GC-ToF-MS) was used for their quantitation using stable isotope dilution analysis (SIDA) or standard addition (SA) methods. Odour activity values (OAV) were calculated for 19 out of 21 key odorants. Tempeh was fermented for 5 days and fried, and the main aroma compounds were found to be the following: 2-acetyl-1-pyrroline, (FD=1024, OAV 1380), 2-ethyl-3,5-dimethylpyrazine (FD=512, OAV 338), dimethyl trisulfide, (FD=512, OAV 900), methional (FD=512, OAV 930), 2-methylpropanal (FD=512, OAV 311) and (E,E)-2,4-decadienal (FD=512, OAV 455). The frying process induced the increase or appearance of the main key odorants in tempeh.

  4. Gas chromatographic determination of volatile congeners in spirit drinks: interlaboratory study.

    PubMed

    Kelly, J; Chapman, S; Brereton, P; Bertrand, A; Guillou, C; Wittkowski, R

    1999-01-01

    An interlaboratory study of a gas chromatographic (GC) method for the determination of volatile congeners in spirit drinks was conducted; 31 laboratories from 8 countries took part in the study. The method uses GC with flame ionization detection and incorporates several quality control measures which permit the choice of chromatographic system and conditions to be selected by the user. Spirit drink samples were prepared and sent to participants as 10 blind duplicate or split-level test materials for the determination of 1,1-diethoxyethane (acetal), 2-methylbutan-1-ol (active amyl alcohol), 3-methylbutan-1-ol (isoamyl alcohol), methanol (methyl alcohol), ethyl ethanoate (ethyl acetate), butan-1-ol (n-butanol), butan-2-ol (sec-butanol), 2-methylpropan-1-ol (isobutyl alcohol), propan-1-ol (n-propanol), and ethanal (acetaldehyde). The precision of the method for 9 of the 10 analytes was well within the range predicted by the Horwitz equation. The precision of the most volatile analyte, ethanal, was just above statistically predicted levels. This method is recommended for official regulatory purposes. PMID:10589492

  5. bFGF interaction and in vivo angiogenesis inhibition by self-assembling sulfonic acid-based copolymers.

    PubMed

    García-Fernández, L; Aguilar, M R; Ochoa-Callejero, L; Abradelo, C; Martínez, A; San Román, J

    2012-01-01

    The antiangiogenic activity of different families of biocompatible and non-toxic polymer drugs based on 2-acrylamido-2-methylpropane sulfonic acid (AMPS) or polymethacrylic derivatives of 5-aminonaphthalen sulfonic acid (MANSA) is analyzed using directed in vivo angiogenesis assay and correlated with in vitro results. These active compounds were copolymerized with butylacrylate (BA) and N-vinylpyrrolidone in order to obtain two families of copolymers with different properties in aqueous media. The most hydrophobic copolymers poly(BA-co-MANSA) and poly(BA-co-AMPS) formed amphiphilic copolymers and presented micellar morphology in aqueous media. This supramolecular organization of the copolymers had a clear effect on bioactivity. Poly(BA-co-MANSA) copolymers showed the best antiangiogenic activity and very low toxicity at relatively low dose, with the possibility to be injected directly in the solid tumors alone or in combination with other therapeutic agents such as anti-VEGF drugs. The obtained results demonstrate that not only the chemical structure but also the supramolecular organization of the macromolecules plays a key role in the anti-angiogenic activity of these active polymers.

  6. Development and characterization of a novel, antimicrobial, sterile hydrogel dressing for burn wounds: single-step production with gamma irradiation creates silver nanoparticles and radical polymerization.

    PubMed

    Boonkaew, Benjawan; Barber, Philip M; Rengpipat, Sirirat; Supaphol, Pitt; Kempf, Margit; He, Jibao; John, Vijay T; Cuttle, Leila

    2014-10-01

    Patients with burn wounds are susceptible to wound infection and sepsis. This research introduces a novel burn wound dressing that contains silver nanoparticles (SNPs) to treat infection in a 2-acrylamido-2-methylpropane sulfonic acid sodium salt (AMPS-Na(+) ) hydrogel. Silver nitrate was dissolved in AMPS-Na(+) solution and then exposed to gamma irradiation to form SNP-infused hydrogels. The gamma irradiation results in a cross-linked polymeric network of sterile hydrogel dressing and a reduction of silver ions to form SNPs infused in the hydrogel in a one-step process. About 80% of the total silver was released from the hydrogels after 72 h immersion in simulated body fluid solution; therefore, they could be used on wounds for up to 3 days. All the hydrogels were found to be nontoxic to normal human dermal fibroblast cells. The silver-loaded hydrogels had good inhibitory action against Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. Results from a pilot study on a porcine burn model showed that the 5-mM silver hydrogel was efficient at preventing bacterial colonization of wounds, and the results were comparable to the commercially available silver dressings (Acticoat(TM) , PolyMem Silver(®) ). These results support its use as a potential burn wound dressing.

  7. Direct nuclear magnetic resonance observation of odorant binding to mouse odorant receptor MOR244-3.

    PubMed

    Burger, Jessica L; Jeerage, Kavita M; Bruno, Thomas J

    2016-06-01

    Mammals are able to perceive and differentiate a great number of structurally diverse odorants through the odorant's interaction with odorant receptors (ORs), proteins found within the cell membrane of olfactory sensory neurons. The natural gas industry has used human olfactory sensitivity to sulfur compounds (thiols, sulfides, etc.) to increase the safety of fuel gas transport, storage, and use through the odorization of this product. In the United States, mixtures of sulfur compounds are used, but the major constituent of odorant packages is 2-methylpropane-2-thiol, also known as tert-butyl mercaptan. It has been fundamentally challenging to understand olfaction and odorization due to the low affinity of odorous ligands to the ORs and the difficulty in expressing a sufficient number of OR proteins. Here, we directly observed the binding of tert-butyl mercaptan and another odiferous compound, cis-cyclooctene, to mouse OR MOR244-3 on living cells by saturation transfer difference (STD) nuclear magnetic resonance (NMR) spectroscopy. This effort lays the groundwork for resolving molecular mechanisms responsible for ligand binding and resulting signaling, which in turn will lead to a clearer understanding of odorant recognition and competition.

  8. Fabrication, modeling and optimization of an ionic polymer gel actuator

    NASA Astrophysics Data System (ADS)

    Jo, Choonghee; Naguib, Hani E.; Kwon, Roy H.

    2011-04-01

    The modeling of the electro-active behavior of ionic polymer gel is studied and the optimum conditions that maximize the deflection of the gel are investigated. The bending deformation of polymer gel under an electric field is formulated by using chemo-electro-mechanical parameters. In the modeling, swelling and shrinking phenomena due to the differences in ion concentration at the boundary between the gel and solution are considered prior to the application of an electric field, and then bending actuation is applied. As the driving force of swelling, shrinking and bending deformation, differential osmotic pressure at the boundary of the gel and solution is considered. From this behavior, the strain or deflection of the gel is calculated. To find the optimum design parameter settings (electric voltage, thickness of gel, concentration of polyion in the gel, ion concentration in the solution, and degree of cross-linking in the gel) for bending deformation, a nonlinear constrained optimization model is formulated. In the optimization model, a bending deflection equation of the gel is used as an objective function, and a range of decision variables and their relationships are used as constraint equations. Also, actuation experiments are conducted using poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) gel and the optimum conditions predicted by the proposed model have been verified by the experiments.

  9. Volatile compound profile of sous-vide cooked lamb loins at different temperature-time combinations.

    PubMed

    Roldán, Mar; Ruiz, Jorge; Del Pulgar, José Sánchez; Pérez-Palacios, Trinidad; Antequera, Teresa

    2015-02-01

    Lamb loins were subjected to sous-vide cooking at different combinations of temperature (60 and 80°C) and time (6 and 24h) to assess the effect on the volatile compound profile. Major chemical families in cooked samples were aliphatic hydrocarbons and aldehydes. The volatile compound profile in sous-vide cooked lamb loin was affected by the cooking temperature and time. Volatile compounds arising from lipid oxidation presented a high abundance in samples cooked at low or moderate cooking conditions (60°C for 6 and 24h, 80°C for 6h), while a more intense time and temperature combination (80°C for 24h) resulted on a higher concentration of volatile compounds arising from Strecker degradations of amino acids, as 2-methylpropanal and 3-methylbutanal. Therefore, sous-vide cooking at moderately high temperatures for long times would result in the formation of a stronger meaty flavor and roast notes in lamb meat. PMID:25306511

  10. γ-Unsaturated aldehydes as potential Lilial replacers.

    PubMed

    Schroeder, Martin; Mathys, Marion; Ehrensperger, Nadja; Büchel, Michelle

    2014-10-01

    A series of Claisen rearrangements was undertaken in order to find a replacement for Lilial (=3-(4-(tert-butyl)phenyl)-2-methylpropanal), a high-tonnage perfumery ingredient with a lily-of-the-valley odour, which is a CMR2 material [1]. 5,7,7-Trimethyl-4-methyleneoctanal (10), the synthesis of which is described, became the main lead. It possesses an odour which is very close to that of Lilial but lacks its substantivity. Aldehydes with higher molecular weights than that of 10 were, therefore, synthesised in order to boost substantivity and to understand the structural requirements for a 'Lilial' odour. The aldehydes were obtained via Claisen rearrangements of 'exo-methylidene' vinyl ethers, allenyl vinyl ethers, or allenyl allyl ethers. Alternatively, coupling of terminal alkynes with allyl alcohols led to the desired aldehydes. Derivatives of 10 and their sila analogues were also synthesised. The olfactory properties of all synthesised molecules were evaluated for possible structure-odour relationships (SOR).

  11. [Analysis of the vol atiles from pigeon's excrement with capillary gas chromatography].

    PubMed

    He, F; Sun, Y; Huang, A; Sun, Y

    1997-01-01

    The volatiles from pigeon's excrement were obtained with a simultaneous distillation and extraction (SDE) equipment. The chemical composition of the volatiles was examined by means of capillary gas chromatography and combined gas chromatography-mass spectrometry. Forty seven constitutents of the volatiles were identified by gas chromatography-mass spectrometry. Of these compounds, thirty nine were further identified by measuring their temperature-programmed retention indexes or retention times on OV-1 and PEG-20M columns and making comparison with those of the corresponding authentic samples. The total compounds identified make 57% of the total peak areas. The compound classes consist of alcohols (4), aldehydes (11), ketones(4), acids (8), esters (5), and phenols (2), amounting to 43.68% of the total peak areas. The ten compounds with highest contents are, hexadecanoic acid (9.03%), ethyl acetate (6.85%), ethanol (4.03%), 1-ethoxy-2-methylpropane (3.87%), acetic acid (3.23%), heptadecane-(8)-carbonic acid (3.20%), (Z,Z)-9,12-octadecadienoic acid (3.18%), nonanal (2.85%), 1,2-benzenedicarboxylic, dibutyl ester (2.65%), and acetaldehyde (2.32%). Pigeon's excrement has long been used as a Chinese traditional medicine for the therapeutic treatment of haemorrhoid. Some of the constituents identified in the work have been reported to have antibacterial activities.

  12. Improved polymers for enhanced-oil-recovery synthesis and rheology. Fifth annual report, October 1981-September 1982

    SciTech Connect

    McCormick, C.L.; Hester, R.D.; Neidlinger, H.H.; Wildman, G.C.

    1983-10-01

    The goal of this project is to gain a more complete understanding of structure/property/performance interrelationships of water-soluble polymers which can aid industry in commercial production of polymers which are more efficient than those presently used. During the past the following have been accomplished: synthesis of model dextran-g-poly(acrylamide-co-sodium acrylates); synthesis of model dextran-g-poly(acrylamide-co-sodium-2-acrylamido-2-methylpropane sulfonates); characterization of model copolymers by elemental analysis, C-13NMR, and viscometry; study of dilute solution properties of the models including the effects of temperature, salt, pH; rheological studies of model graft copolymers; development of mathematical models, new calibration functions, analytical methods, and data acquisition techniques for aqueous size exclusion chromatography; application of quasielastic light scattering techniques to the study of hydrodynamic volume concepts; preferential and overall solvation studies of AN/NaA and AM/NaAMPS copolymers; study of phase behavior of model polymers in mono- and multivalent electrolytes at different polymer and salt concentrations as a function of temperature; education and training of students in basic energy research.

  13. Configuration control on the shape memory stiffness of molecularly imprinted polymer for specific uptake of creatinine

    NASA Astrophysics Data System (ADS)

    Ang, Qian Yee; Zolkeflay, Muhammad Helmi; Low, Siew Chun

    2016-04-01

    In this study, sol-gel processing was proposed to prepare a creatinine (Cre)-imprinted molecularly imprinted polymer (MIP). The intermolecular interaction constituted by the cross-linkers, i.e., 2-acrylamido-2-methylpropane-sulfonic acid (AMPS) and aluminium ion (Al3+), was studied and compared in order to form a confined matrix that promises the effectiveness of molecular imprinting. In view of the shape recognition, the hydrogen bonded Cre-AMPS did not demonstrate good recognition of Cre, with Cre binding found only at 5.70 ± 0.15 mg g-1 of MIP. Whilst, MIP cross-linked using Al3+ was able to attain an excellent Cre adsorption capacity of 19.48 ± 0.64 mg g-1 of MIP via the stronger ionic interaction of Cre-Al3+. Based on the Scatchard analysis, a higher Cre concentration in testing solution required greater driving force to resolve the binding resistance of Cre molecules, so as to have a precise Cre binding with shape factor. The molecular recognition ability of Cre-MIP in present work was shape-specific for Cre as compared to its structural analogue, 2-pyrrolidinone (2-pyr), by an ideal selectivity coefficient of 6.57 ± 0.10. In overall, this study has come up with a practical approach on the preparation of MIP for the detection of renal dysfunction by point-of-care Cre testing.

  14. Use of Lactococcus lactis subsp. cremoris NCDO 763 and α-ketoglutarate to improve the sensory quality of dry fermented sausages.

    PubMed

    Herranz, B; Fernández, M; Hierro, E; Bruna, J M; Ordóñez, J A; de la Hoz, L

    2004-01-01

    The aim of the present work was to enhance the degradation of free amino acids in dry fermented sausages as precursors of volatile compounds responsible for the ripened flavour. For this purpose, Lactococcus lactis subsp. cremoris NCDO 763, its intracellular cell free extract (ICFE) and α-ketoglutarate were added to sausages. Papain was also used to increase the amount of free amino acids. When L. lactis was inoculated in sausages, an increase in the proteolytic phenomena was observed. The addition of α-ketoglutarate increased transamination phenomena in batches where it was added. The enhancement of these phenomena determined a noticeable rise in the content of glutamic acid (the main final product in transamination reactions) and a decrease, among other amino acids, of valine and leucine, with the formation of high amounts of their derivatives 2-methylpropanal and 3-methylbutanal. These aldehydes are responsible for the ripened flavour of dry fermented sausages. Sensory analysis showed an improvement of odour and flavour when L. lactis and α-ketoglutarate were combined. On the other hand, the intracellular cell free extract of L. lactis did not show any important activity in relation to amino acid breakdown even when used together with α-ketoglutarate and/or papain. PMID:22063943

  15. Volatile compound profile of sous-vide cooked lamb loins at different temperature-time combinations.

    PubMed

    Roldán, Mar; Ruiz, Jorge; Del Pulgar, José Sánchez; Pérez-Palacios, Trinidad; Antequera, Teresa

    2015-02-01

    Lamb loins were subjected to sous-vide cooking at different combinations of temperature (60 and 80°C) and time (6 and 24h) to assess the effect on the volatile compound profile. Major chemical families in cooked samples were aliphatic hydrocarbons and aldehydes. The volatile compound profile in sous-vide cooked lamb loin was affected by the cooking temperature and time. Volatile compounds arising from lipid oxidation presented a high abundance in samples cooked at low or moderate cooking conditions (60°C for 6 and 24h, 80°C for 6h), while a more intense time and temperature combination (80°C for 24h) resulted on a higher concentration of volatile compounds arising from Strecker degradations of amino acids, as 2-methylpropanal and 3-methylbutanal. Therefore, sous-vide cooking at moderately high temperatures for long times would result in the formation of a stronger meaty flavor and roast notes in lamb meat.

  16. Controlled delivery of valsartan by cross-linked polymeric matrices: Synthesis, in vitro and in vivo evaluation.

    PubMed

    Sohail, Muhammad; Ahmad, Mahmood; Minhas, Muhammad Usman; Ali, Liaqat; Khalid, Ikrima; Rashid, Haroon

    2015-06-20

    The purpose of study was to develop chemically cross-linked chitosan-co-poly(AMPS) hydrogel based on low molecular weight chitosan for pH-responsive and controlled drug delivery of a model drug. Cross-linking was achieved chemically, by using free radical polymerization technique. Polymer (low molecular weight chitosan) was chemically cross-linked with monomer (2-acrylamido-2-methylpropane sulfonic acid) in aqueous medium. N, N'-Methylenebisacrylamide (MBA) was used as cross-linking agent. Sodium hydrogen sulfite (SHS) and ammonium peroxodisulphate (APS) were used as initiators in a chemical reaction. Hydrogels were characterized by FT-IR, SEM and DSC. Swelling studies and pH-sensitivity of hydrogels were studies at pH 1.2 and 7.4. Chitosan-co-poly(AMPS) hydrogels were administered to rabbits orally to evaluate its pharmacokinetic behavior. As a result of successful cross-linking of polymer and monomer, novel co-polymer has been developed, having suitable characteristics as desired for controlled release drug delivery system. Maximum swelling, drug loading and release have been observed at pH 7.4. In vivo results exhibited significant drug release and absorption at pH 7.4 in rabbits. It is concluded that highly swelling chitosan-AMPS based hydrogels were developed having pH independent swelling and pH dependent drug release properties. These hydrogels have great potential to be used for loading and controlled release of various therapeutic agents. PMID:25865571

  17. Sulfonated macro-RAFT agents for the surfactant-free synthesis of cerium oxide-based hybrid latexes.

    PubMed

    Garnier, Jérôme; Warnant, Jérôme; Lacroix-Desmazes, Patrick; Dufils, Pierre-Emmanuel; Vinas, Jérôme; van Herk, Alex

    2013-10-01

    Three types of amphiphatic macro-RAFT agents were employed as compatibilizers to promote the polymerization reaction at the surface of nanoceria for the synthesis of CeO2-based hybrid latexes. Macro-RAFT copolymers and terpolymers were first synthesized employing various combinations of butyl acrylate as a hydrophobic monomer and acrylic acid (AA) and/or 2-acrylamido-2-methylpropane sulfonic acid (AMPS) as hydrophilic monomers. After characterizing the adsorption of these macro-RAFT agents at the cerium oxide surface by UV-visible spectrometry, emulsion copolymerization reactions of styrene and methyl acrylate were then carried out in the presence of the surface-modified nanoceria. Dynamic Light Scattering and cryo-Transmission Electron Microscopy were employed to confirm the hybrid structure of the final CeO2/polymer latexes, and proved that the presence of acrylic acid units in amphiphatic macro-RAFT agents enabled an efficient formation of hybrid structures, while the presence of AMPS units, when combined with AA units, resulted in a better distribution of cerium oxide nanoclusters between latex particles.

  18. Impact of higher alcohols blended in gasoline on light-duty vehicle exhaust emissions.

    PubMed

    Ratcliff, Matthew A; Luecke, Jon; Williams, Aaron; Christensen, Earl; Yanowitz, Janet; Reek, Aaron; McCormick, Robert L

    2013-12-01

    Certification gasoline was splash blended with alcohols to produce four blends: ethanol (16 vol%), n-butanol (17 vol%), i-butanol (21 vol%), and an i-butanol (12 vol%)/ethanol (7 vol%) mixture; these fuels were tested in a 2009 Honda Odyssey (a Tier 2 Bin 5 vehicle) over triplicate LA92 cycles. Emissions of oxides of nitrogen, carbon monoxide, non-methane organic gases (NMOG), unburned alcohols, carbonyls, and C1-C8 hydrocarbons (particularly 1,3-butadiene and benzene) were determined. Large, statistically significant fuel effects on regulated emissions were a 29% reduction in CO from E16 and a 60% increase in formaldehyde emissions from i-butanol, compared to certification gasoline. Ethanol produced the highest unburned alcohol emissions of 1.38 mg/mile ethanol, while butanols produced much lower unburned alcohol emissions (0.17 mg/mile n-butanol, and 0.30 mg/mile i-butanol); these reductions were offset by higher emissions of carbonyls. Formaldehyde, acetaldehyde, and butyraldehyde were the most significant carbonyls from the n-butanol blend, while formaldehyde, acetone, and 2-methylpropanal were the most significant from the i-butanol blend. The 12% i-butanol/7% ethanol blend was designed to produce no increase in gasoline vapor pressure. This fuel's exhaust emissions contained the lowest total oxygenates among the alcohol blends and the lowest NMOG of all fuels tested.

  19. Mid-infrared surface transmitting and detecting quantum cascade device for gas-sensing

    PubMed Central

    Harrer, Andreas; Szedlak, Rolf; Schwarz, Benedikt; Moser, Harald; Zederbauer, Tobias; MacFarland, Donald; Detz, Hermann; Andrews, Aaron Maxwell; Schrenk, Werner; Lendl, Bernhard; Strasser, Gottfried

    2016-01-01

    We present a bi-functional surface emitting and surface detecting mid-infrared device applicable for gas-sensing. A distributed feedback ring quantum cascade laser is monolithically integrated with a detector structured from a bi-functional material for same frequency lasing and detection. The emitted single mode radiation is collimated, back reflected by a flat mirror and detected by the detector element of the sensor. The surface operation mode combined with the low divergence emission of the ring quantum cascade laser enables for long analyte interaction regions spatially separated from the sample surface. The device enables for sensing of gaseous analytes which requires a relatively long interaction region. Our design is suitable for 2D array integration with multiple emission and detection frequencies. Proof of principle measurements with isobutane (2-methylpropane) and propane as gaseous analytes were conducted. Detectable concentration values of 0–70% for propane and 0–90% for isobutane were reached at a laser operation wavelength of 6.5 μm utilizing a 10 cm gas cell in double pass configuration. PMID:26887891

  20. Comparison of Aroma-Active Volatiles in Oolong Tea Infusions Using GC-Olfactometry, GC-FPD, and GC-MS.

    PubMed

    Zhu, JianCai; Chen, Feng; Wang, LingYing; Niu, YunWei; Yu, Dan; Shu, Chang; Chen, HeXing; Wang, HongLin; Xiao, ZuoBing

    2015-09-01

    The aroma profile of oolong tea infusions (Dongdingwulong, DDWL; Tieguanyin, TGY; Dahongpao, DHP) were investigated in this study. Gas chromatography-olfactometry (GC-O) with the method of aroma intensity (AI) was employed to investigate the aroma-active compounds in tea infusions. The results presented forty-three, forty-five, and forty-eight aroma-active compounds in the TGY, DHP, and DDWL infusions, including six, seven, and five sulfur compounds, respectively. In addition, the concentration of volatile compounds in the tea infusions was further quantitated by solid phase microextraction-gas chromatography (SPME)-GC-MS and SPME-GC-flame photometric detection (FPD). Totally, seventy-six and thirteen volatile and sulfur compounds were detected in three types of tea infusions, respectively. Quantitative results showed that forty-seven aroma compounds were at concentrations higher than their corresponding odor thresholds. On the basis of the odor activity values (OAVs), 2-methylpropanal (OAV: 230-455), 3-methylbutanal (1-353), 2-methylbutanal (34-68), nerolidol (108-184), (E)-2-heptenal (148-294), hexanal (134-230), octanal (28-131), β-damascenone (29-59), indole (96-138), 6-methyl-5-hepten-2-one (34-67), (R)-(-)-linalool (63-87), and dimethyl sulfide (7-1320) presented relatively higher OAVs than those of other compounds, indicating the importance of these compounds in the overall aroma of tea infusions. PMID:26257073

  1. Mid-infrared surface transmitting and detecting quantum cascade device for gas-sensing.

    PubMed

    Harrer, Andreas; Szedlak, Rolf; Schwarz, Benedikt; Moser, Harald; Zederbauer, Tobias; MacFarland, Donald; Detz, Hermann; Andrews, Aaron Maxwell; Schrenk, Werner; Lendl, Bernhard; Strasser, Gottfried

    2016-01-01

    We present a bi-functional surface emitting and surface detecting mid-infrared device applicable for gas-sensing. A distributed feedback ring quantum cascade laser is monolithically integrated with a detector structured from a bi-functional material for same frequency lasing and detection. The emitted single mode radiation is collimated, back reflected by a flat mirror and detected by the detector element of the sensor. The surface operation mode combined with the low divergence emission of the ring quantum cascade laser enables for long analyte interaction regions spatially separated from the sample surface. The device enables for sensing of gaseous analytes which requires a relatively long interaction region. Our design is suitable for 2D array integration with multiple emission and detection frequencies. Proof of principle measurements with isobutane (2-methylpropane) and propane as gaseous analytes were conducted. Detectable concentration values of 0-70% for propane and 0-90% for isobutane were reached at a laser operation wavelength of 6.5 μm utilizing a 10 cm gas cell in double pass configuration. PMID:26887891

  2. Mid-infrared surface transmitting and detecting quantum cascade device for gas-sensing.

    PubMed

    Harrer, Andreas; Szedlak, Rolf; Schwarz, Benedikt; Moser, Harald; Zederbauer, Tobias; MacFarland, Donald; Detz, Hermann; Andrews, Aaron Maxwell; Schrenk, Werner; Lendl, Bernhard; Strasser, Gottfried

    2016-02-18

    We present a bi-functional surface emitting and surface detecting mid-infrared device applicable for gas-sensing. A distributed feedback ring quantum cascade laser is monolithically integrated with a detector structured from a bi-functional material for same frequency lasing and detection. The emitted single mode radiation is collimated, back reflected by a flat mirror and detected by the detector element of the sensor. The surface operation mode combined with the low divergence emission of the ring quantum cascade laser enables for long analyte interaction regions spatially separated from the sample surface. The device enables for sensing of gaseous analytes which requires a relatively long interaction region. Our design is suitable for 2D array integration with multiple emission and detection frequencies. Proof of principle measurements with isobutane (2-methylpropane) and propane as gaseous analytes were conducted. Detectable concentration values of 0-70% for propane and 0-90% for isobutane were reached at a laser operation wavelength of 6.5 μm utilizing a 10 cm gas cell in double pass configuration.

  3. Semiconductor/solid electrolyte junctions for optical information storage. Solid-state electrochromic cell using lutecium diphthalocyanine

    NASA Astrophysics Data System (ADS)

    Sammells, A. F.; Pujare, N. U.

    1986-01-01

    The overall program goal is to perform a basic investigation of photoelectrochemical and electrochemical effects by electrochromic materials in solid polymer electrolyte (SPE) containing solid-state cells. Initial investigations have been directed towards reversible electrochromic behavior at the interface between lutecium diphthalocyanine deposited onto electronically conducting glass, and the homopolymer poly-2-acrylamido -2-methylpropane sulfonic acid (poly(Amps)). We wish to report here some recent work on solid-state electrochromic cells in which ionic mediation to thin-film deposits of lutecium diphthalocyanine is via the homopolymer poly-2-acrylamido-2-methyl propane sulfonic acid (poly-Amps). Separation between the working (LuH(Pc)2 deposited onto SnO2 conducting glass) and counter (CeCl3 in poly (Amps)) electrodes in these solid-state cells was realized by the use of the insoluble copolymer perfluorosulfonic acid (Nafion). Solid-state electrochromic cells were prepared using the supporting electrolytes (SEs) 0.1M Na2SO4 and 0.1M KCl. Upon subjecting the cell to anodic and cathodic voltage scans, up to four distinct color changes were observed varying from red (at anodic potentials) to violet (at cathodic potentials). Formation of the violet lutecium diphthalocyanine reduction product was not found contingent upon the absence of alkali cations as reported by others.

  4. Structural effects in photopolymerized sodium AMPS hydrogels crosslinked with poly(ethylene glycol) diacrylate for use as burn dressings.

    PubMed

    Nalampang, Kanarat; Panjakha, Rachanida; Molloy, Robert; Tighe, Brian J

    2013-01-01

    Synthetic hydrogel polymers were prepared by free radical photopolymerization in aqueous solution of the sodium salt of 2-acrylamido-2-methylpropane sulfonic acid (Na-AMPS). Poly(ethylene glycol) diacrylate (PEGDA) and 4,4'-azo-bis(4-cyanopentanoic acid) were used as the crosslinker and UV-photoinitiator, respectively. The effects of varying the Na-AMPS monomer concentration within the range of 30-50% w/v and the crosslinker concentration within the range of 0.1-1.0% mol (relative to monomer) were studied in terms of their influence on water absorption properties. The hydrogel sheets exhibited extremely high swelling capacities in aqueous media which were dependent on monomer concentration, crosslink density, and the ionic strength and composition of the immersion medium. The effects of varying the number-average molecular weight of the PEGDA crosslinker from [Formula: see text] = 250 to 700 were also investigated. Interestingly, it was found that increasing the molecular weight and therefore the crosslink length at constant crosslink density decreased both the rate of water absorption and the equilibrium water content. Cytotoxicity testing by the direct contact method with mouse fibroblast L929 cells indicated that the synthesized hydrogels were nontoxic. On the basis of these results, it is considered that photopolymerized Na-AMPS hydrogels crosslinked with PEGDA show considerable potential for biomedical use as dressings for partial thickness burns. This paper describes some structural effects which are relevant to their design as biomaterials for this particular application. PMID:23796031

  5. Determination of direct photolysis rate constants and OH radical reactivity of representative odour compounds in brewery broth using a continuous flow-stirred photoreactor

    NASA Astrophysics Data System (ADS)

    Jürgens, Marion; Jacob, Fritz; Ekici, Perihan; Friess, Albrecht; Parlar, Harun

    A method based on photolysis was developed for the appropriate treatment of organic pollutants in air exhausting from breweries upon wort decoction, and thereby causing smell nuisance. A continuous flow stirred photoreactor was built-up exclusively, allowing OH radicals to react with selected odorous compounds contained in exhaust vapours, such as: 2-methylpropanal, 3-methylbutanal, 2-methylbutanal, 3-methyl-1-butanol, n-hexanal, 2-methylbutyl isobutyrate, 2-undecanone, phenyl acetaldehyde, myrcene, limonene, linalool, humulene, dimethylsulphide, and dimethyltrisulphide. These substances were quantified in brewery broth before and after UV irradiation using high-resolution gas chromatography-mass spectrometry (HRGC-MS). For odour analysis, high-resolution gas chromatography-flame ionisation detection (HRGC-FID) coupled with sensory methods was used. Determined quantum yields of about 10 -3 for phenyl acetaldehyde, myrcene, and humulene pointed out that direct photolysis contributed to their decay. Quantum yields of below 10 -4 for the other substances indicated that UV irradiation did not contribute significantly to their degradation processes. Hydroxyl radical reaction rate constants and Henry constants of organic compounds were also measured. Substances accompanied with low Henry constants converted rapidly, whereas those with higher ones, relatively slowly. Determined aroma values concluded that after UV-H 2O 2 treatment, only dimethylsulphide and myrcene remained as important odorous compounds, but in significantly reduced concentrations. The UV-H 2O 2 treatment of brewery broth has been proved effective to reduce smell-irritating substances formed upon wort decoction.

  6. On the atmospheric degradation of multifunctional organic compounds by NO3 and SO4- radicals in aqueous solution

    NASA Astrophysics Data System (ADS)

    Schöne, Luisa; Stieger, Bastian; Weller, Christian; Herrmann, Hartmut

    2014-05-01

    The atmospheric decomposition and transformation of a large number of organic compounds is initiated by radicals in the gas and aqueous phase. With increasing degree of oxidation and functionalization, organics become less volatile and more water soluble and partition into aqueous particles and cloud droplets where the oxidation by radicals continues. NO3 and SO4- radicals dominate the atmospheric aqueous phase besides OH radicals. Within this work, temperature dependent kinetic investigations were conducted by use of a laser flash photolysis laser long path absorption (LFPLLPA) setup. Second order rate constants for the reactions of 3-methoxy-1-propanol, diethylether, methylpropylether, 2-methyloxirane-2-carbaldehyde, 2,3-dihydroxy-2-methylpropanal, pyruvic, glyoxylic and glycolic acid as well as glyoxal, methylglyoxal and glycolaldehyde with NO3 and SO4- radicals were measured in a temperature range of 278 and 318 K applying pseudo-first order kinetics. The reactivity of the acids and their anions were investigated separately adjusting the pH to pH 1 or pH 8 for the acid or the anion form, respectively. From these measurements, activation parameters were derived. Measured k2nd range from 106 - 108 M1 s1. The kinetic and thermodynamic parameters as well as reaction mechanisms will be discussed within this contribution.

  7. SANS Study of Static Structure of The Double Network Polymers

    NASA Astrophysics Data System (ADS)

    Tominaga, Taiki; Takata, Shin-ichi; Suzuki, Jun-ichi; Aizawa, Kazuya; Seto, Hideki; Arai, Masatoshi

    The freeze-dried double-network hydrogels (DN-polymers) have cross-linked aqueous polymer networks giving unique mechanical properties [1]. The Young's modulus of the DN-polymers is nearly unchanged around 102 MPa in the relative humidity (RH) between 0 and 80%. The DN-polymers also show maximum values in both Young's modulus and fracture stress around 30% RH, which corresponds to the water content of about 7 wt.%, in contrast with the plastics for which tinny amount of water causes significant decrease of mechanical properties. Small-angle neutron scattering (SANS) measurements were carried out to investigate the humidity dependence of the nanoscaled structure of the DN-polymers. Several SANS profiles obtained for un-deformed DN-polymers made of poly- (2-acrylamido-2-methylpropane sulfonic acid) sodium salt (PNaAMPS) and polyacrylamide (PAAm) are compared with each other. The SANS results show that water is adsorbed on the structure larger than a mesh-size of the polymer network at low RH but is adsorbed gradually also on the structure in a scale of the segment of the polymer with increasing RH.

  8. A flow reactor study of neopentane oxidation at 8 atmospheres: Experiments and modeling

    SciTech Connect

    Wang, S.; Miller, D.L.; Cernansky, N.P.; Curran, H.J.; Pitz, W.J.; Westbrook, C.K.

    1999-08-01

    An existing detailed chemical kinetic reaction mechanism for neopentane oxidation is applied to new experimental measurements, taken in a flow reactor operating at a pressure of 8 atm. The reactor temperature ranged from 620 K to 810 K and flow rates of the reactant gases neopentane, oxygen, and nitrogen were 0.285, 7.6, and 137.1 standard liter per minute (SLM), respectively, producing an equivalence ratio of 0.3. Initial simulations identified some deficiencies in the existing model and the paper presents modifications which included upgrading the thermodynamic parameters of alkyl radical and alkylperoxy radical species, adding an alternative isomerization reaction of hydroperoxy-neopentyl-peroxy, and a multistep reaction sequence for 2-methylpropan-2-yl radical with molecular oxygen. These changes improved the calculation for the overall reactivity and the concentration profiles of the following primary products: formaldehyde, acetone, isobutene; 3,3-dimethyloxetane, methacrolein, carbon monoxide, carbon dioxide, and water. Experiments indicate that neopentane shows negative temperature coefficient behavior similar to other alkanes, though it is not as pronounced as that shown by n-pentane for example. Modeling results indicate that this behavior is caused by the {beta}-scission of the neopentyl radical and the chain propagation reactions of the hydroperoxyl-neopentyl radical.

  9. Characterization of the key aroma compounds in an american bourbon whisky by quantitative measurements, aroma recombination, and omission studies.

    PubMed

    Poisson, Luigi; Schieberle, Peter

    2008-07-23

    Thirty-one of the 45 odor-active compounds previously identified by us in an American Bourbon whisky were quantified by stable isotope dilution assays. Also for this purpose, new synthetic pathways were developed for the synthesis of the deuterium-labeled whisky lactone as well as for gamma-nona- and gamma-decalactone. To obtain the odor activity values (OAVs), the concentrations measured were divided by the odor thresholds of the odorants determined in water/ethanol (6:4 by vol.). Twenty-six aroma compounds showed OAVs >1, among which ethanol, ethyl (S)-2-methylbutanoate, 3-methylbutanal, 4-hydroxy-3-methoxybenzaldehyde, (E)-beta-damascenone, ethyl hexanoate, ethyl butanoate, ethyl octanoate, 2-methylpropanal, (3S,4S)- cis-whiskylactone, (E, E)-2,4-decadienal, 4-allyl-2-methoxyphenol, ethyl-3-methylbutanoate, and ethyl 2-methylpropanoate showed the highest values. The overall aroma of the Bourbon whisky could be mimicked by an aroma recombinate consisting of the 26 key odorants in their actual concentrations in whisky using water/ethanol (6:4 by vol.) as the matrix. Omission experiments corroborated the importance of, in particular, 4-hydroxy-3-methoxybenzaldehyde, (3S,4S)-cis-whiskylactone, ethanol, and the entire group of esters for the overall aroma of the Bourbon whisky.

  10. Characterization of protein hydrolysis and odor-active compounds of fish sauce inoculated with Virgibacillus sp. SK37 under reduced salt content.

    PubMed

    Lapsongphon, Nawaporn; Cadwallader, Keith R; Rodtong, Sureelak; Yongsawatdigul, Jirawat

    2013-07-10

    The effect of Virgibacillus sp. SK37, together with reduced salt content, on fish sauce quality, particularly free amino acids and odor-active compounds, was investigated. Virgibacillus sp. SK37 was inoculated with an approximate viable count of 5 log CFU/mL in samples with varied amounts of solar salt, for example, 10, 15, and 20% of total weight. Eighteen selected odorants were quantitated by stable isotope dilution assays (SIDA), and their odor activity values (OAVs) were calculated. Samples prepared using 10% salt underwent spoilage after 7 days of fermentation. The viable count of Virgibacillus sp. SK37 was found over 3 months in the samples containing 15 and 20% salt. However, acceleration of protein hydrolysis was not pronounced in inoculated samples at both 15 and 20% salt. Virgibacillus sp. SK37, together with salt contents reduced to 15-20%, appeared to increase the content of 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, acetic acid, and 2-methylpropanoic acid. However, only aldehydes were found to have an effect on the overall aroma of fish sauce based on high OAVs, suggesting that the inoculation of samples with Virgibacillus sp. SK37 under reduced salt contents of 15-20% likely contributed to stronger malty or dark chocolate notes. PMID:23768048

  11. Determination of stability constants of complexes of neutral analytes with charged cyclodextrins by affinity capillary electrophoresis.

    PubMed

    Beneš, Martin; Zusková, Iva; Svobodová, Jana; Gaš, Bohuslav

    2012-03-01

    A novel procedure for the determination of stability constants in systems with neutral analytes and charged complexation agents by affinity capillary electrophoresis was established. This procedure involves all necessary corrections to achieve precise and reliable data. Temperature, ionic strength, and viscosity corrections were applied. Based on the conductivity measurements, the average temperature of the background electrolyte in the capillary was kept at the constant value of 25°C by decreasing the temperature of the cooling medium. The viscosity correction was performed using the viscosity ratio determined by an external viscosimeter. The electrophoretical measurements were performed, at first, at constant ionic strength. In this case, the increase of ionic strength caused by increasing complexation agent concentration was compensated by changing of the running buffer concentration. Subsequently the dependence of the analyte effective mobility on the complexation agent concentration was measured without the ionic strength compensation (at variable ionic strength). The new procedure for determination of the stability constants even from such data was established. These stability constants are in a very good agreement with those obtained at the constant ionic strength. The established procedure was applied for determination of the thermodynamic stability constants of (R, R)-(+)- and (S, S)-(-)-hydrobenzoin and R- and S-(3-bromo-2-methylpropan-1-ol) complexing with 6-monodeoxy-6-mono(3-hydroxy)propylamino-β-cyclodextrin hydrochloride.

  12. Mid-infrared surface transmitting and detecting quantum cascade device for gas-sensing

    NASA Astrophysics Data System (ADS)

    Harrer, Andreas; Szedlak, Rolf; Schwarz, Benedikt; Moser, Harald; Zederbauer, Tobias; Macfarland, Donald; Detz, Hermann; Andrews, Aaron Maxwell; Schrenk, Werner; Lendl, Bernhard; Strasser, Gottfried

    2016-02-01

    We present a bi-functional surface emitting and surface detecting mid-infrared device applicable for gas-sensing. A distributed feedback ring quantum cascade laser is monolithically integrated with a detector structured from a bi-functional material for same frequency lasing and detection. The emitted single mode radiation is collimated, back reflected by a flat mirror and detected by the detector element of the sensor. The surface operation mode combined with the low divergence emission of the ring quantum cascade laser enables for long analyte interaction regions spatially separated from the sample surface. The device enables for sensing of gaseous analytes which requires a relatively long interaction region. Our design is suitable for 2D array integration with multiple emission and detection frequencies. Proof of principle measurements with isobutane (2-methylpropane) and propane as gaseous analytes were conducted. Detectable concentration values of 0-70% for propane and 0-90% for isobutane were reached at a laser operation wavelength of 6.5 μm utilizing a 10 cm gas cell in double pass configuration.

  13. Recovery of anhydrous Na{sub 2}SO{sub 4} from SO{sub 2}-scrubbing liquor by extractive crystallization: Liquid-liquid equilibria for aqueous solutions of sodium carbonate, sulfate, and/or sulfite plus acetone, 2-propanol, or tert-butyl alcohol

    SciTech Connect

    Lynn, S.; Cos, R.; Prausnitz, J.M. |; Schiozer, A.L.; Jaecksch, W.L.

    1996-11-01

    Sodium carbonate is a superior scrubbing agent for removing SO{sub 2} from combustion gases, but the resulting sodium sulfate (or sulfite) must be recovered for environmental reasons. Recovery by evaporative crystallization is energy-intensive; extractive crystallization provides an attractive alterative when technically feasible. Liquid/liquid equilibrium data were determined for two-phase mixtures containing aqueous solutions of sodium carbonate, sulfate, or sulfite and a polar organic solvent: acetone, 2-propanol, and 2-methylpropan-1-ol (i.e., tert-butyl alcohol). In the salt-saturated two-phase region, data were obtained between the lower consolute temperature and 60 C (50 C for acetone). data were also obtained at 35 C for liquid/liquid systems that were subsaturated with their respective salts and for liquid/liquid systems with overall molar ratios of sodium sulfite/sodium sulfate fixed at 25/75, 50/50, and 75/25. In the latter systems, it was found that the sulfite/sulfate ratios in the organic and aqueous phases were the same, i.e., there is no selectivity by these solvents for one salt relative to the other. The data show that any one of these solvents can be used to extract water from a concentrated solution of either sodium sulfite or sodium sulfate in a countercurrent extractor at 35 C, causing the anhydrous salt to crystallize. The wet solvent can be dried for recycle in a similar countercurrent operation at 35 C, using a saturated solution of Na{sub 2}CO{sub 3} as the drying agent. The number of moles of carbonate required for drying does not exceed the number of moles of sulfite-plus-sulfate precipitated. The process energy is about 0% of that required for single-stage evaporative crystallization of the same liquor.

  14. Oxytetracycline recovery from aqueous media using computationally designed molecularly imprinted polymers.

    PubMed

    Rodríguez-Dorado, Rosalía; Carro, Antonia M; Chianella, Iva; Karim, Kal; Concheiro, Angel; Lorenzo, Rosa A; Piletsky, Sergey; Alvarez-Lorenzo, Carmen

    2016-09-01

    Polymers for recovery/removal of the antimicrobial agent oxytetracycline (OTC) from aqueous media were developed with use of computational design and molecular imprinting. 2-Hydroxyethyl methacrylate, 2-acrylamide-2-methylpropane sulfonic acid (AMPS), and mixtures of the two were chosen according to their predicted affinity for OTC and evaluated as functional monomers in molecularly imprinted polymers and nonimprinted polymers. Two levels of AMPS were tested. After bulk polymerization, the polymers were crushed into particles (200-1000 μm). Pressurized liquid extraction was implemented for template removal with a low amount of methanol (less than 20 mL in each extraction) and a few extractions (12-18 for each polymer) in a short period (20 min per extraction). Particle size distribution, microporous structure, and capacity to rebind OTC from aqueous media were evaluated. Adsorption isotherms obtained from OTC solutions (30-110 mg L(-1)) revealed that the polymers prepared with AMPS had the highest affinity for OTC. The uptake capacity depended on the ionic strength as follows: purified water > saline solution (0.9 % NaCl) > seawater (3.5 % NaCl). Polymer particles containing AMPS as a functional monomer showed a remarkable ability to clean water contaminated with OTC. The usefulness of the stationary phase developed for molecularly imprinted solid-phase extraction was also demonstrated. Graphical Abstract Selection of functional monomers by molecular modeling renders polymer networks suitable for removal of pollutants from contaminated aqueous environments, under either dynamic or static conditions.

  15. Improving the efficiency of configurational-bias Monte Carlo: A density-guided method for generating bending angle trials for linear and branched molecules

    SciTech Connect

    Sepehri, Aliasghar; Loeffler, Troy D.; Chen, Bin

    2014-08-21

    A new method has been developed to generate bending angle trials to improve the acceptance rate and the speed of configurational-bias Monte Carlo. Whereas traditionally the trial geometries are generated from a uniform distribution, in this method we attempt to use the exact probability density function so that each geometry generated is likely to be accepted. In actual practice, due to the complexity of this probability density function, a numerical representation of this distribution function would be required. This numerical table can be generated a priori from the distribution function. This method has been tested on a united-atom model of alkanes including propane, 2-methylpropane, and 2,2-dimethylpropane, that are good representatives of both linear and branched molecules. It has been shown from these test cases that reasonable approximations can be made especially for the highly branched molecules to reduce drastically the dimensionality and correspondingly the amount of the tabulated data that is needed to be stored. Despite these approximations, the dependencies between the various geometrical variables can be still well considered, as evident from a nearly perfect acceptance rate achieved. For all cases, the bending angles were shown to be sampled correctly by this method with an acceptance rate of at least 96% for 2,2-dimethylpropane to more than 99% for propane. Since only one trial is required to be generated for each bending angle (instead of thousands of trials required by the conventional algorithm), this method can dramatically reduce the simulation time. The profiling results of our Monte Carlo simulation code show that trial generation, which used to be the most time consuming process, is no longer the time dominating component of the simulation.

  16. Infrared absorption of 1-chloro-2-methyl-2-propyl [ṡC(CH3)2CH2Cl] and 2-chloro-2-methylpropyl [ṡCH2C(CH3)2Cl] radicals produced in the addition reactions of Cl with isobutene (i-C4H8) in solid para-hydrogen

    NASA Astrophysics Data System (ADS)

    Chou, Ching-Yin; Lee, Yuan-Pern

    2016-10-01

    The addition reactions of chlorine atom with isobutene (i-C4H8) in solid para-hydrogen (p-H2) were investigated with infrared (IR) absorption spectra. When a p-H2 matrix containing Cl2 and isobutene was irradiated with ultraviolet light at 365 nm, intense lines in a set at 534.5, 1001.0, 1212.9, 1366.0, 2961.6, and 2934.7 cm-1, and several weaker others due to the 1-chloro-2-methyl-2-propyl radical, ṡC(CH3)2CH2Cl, and those in a second set including intense ones at 642.7, 799.2, 1098.2, 1371.8, and 3027.3 cm-1 due to the 2-chloro-2-methylpropyl radical, ṡCH2C(CH3)2Cl, appeared; the ratio of ṡC(CH3)2CH2Cl to ṡCH2C(CH3)2Cl was approximately (3 ± 1):1. The observed wavenumbers and relative intensities agree with the vibrational wavenumbers and IR intensities predicted with the B3PW91/aug-cc-pVTZ method. That the Cl atom adds to both carbons of the C=C bond of isobutene with the terminal site slightly favored is consistent with the energies of products predicted theoretically, but is in contrast to the reaction of Cl + propene in solid p-H2 in which the addition of Cl to mainly the central C atom was previously reported. The role of the p-H2 matrix in affecting the reaction paths is discussed. Absorption lines of the complex i-C4H8ṡCl2 and the dichloro-product anti-1,2-dichloro-2-methylpropane, a-CH2ClCCl(CH3)2, are also characterized.

  17. Synthesis of Discodermolide Subunits by S(E)2' Addition of Nonracemic Allenylstannanes to Aldehydes.

    PubMed

    Marshall, James A.; Lu, Zhi-Hui; Johns, Brian A.

    1998-02-01

    Three subunits, 15, 29, and 34, of the immunosuppressant discodermolide were prepared starting from (S)-3-[(tert-butyldimethylsilyl)oxy]-2-methylpropanal ((S)-1) and the enantioenriched allenylstannanes (P)-2a, (P)-2b, and (P)-31. The route to 15 involved BF(3)-promoted addition of stannane (P)-2a to aldehyde (S)-1 which afforded the syn,syn-homopropargylic alcohol adduct 3 in 97% yield. The derived p-methoxybenzylidene acetal 5 was treated with Red-Al to effect cleavage of the pivalate and reduction of the double bond leading to the (E)-allylic alcohol 6. Sharpless epoxidation and subsequent addition of Me(2)CuCNLi(2) yielded the syn,syn,syn,anti stereopentad, diol 8. Protection of the secondary alcohol and oxidation of the primary gave aldehyde 12, which was treated with the alpha-bromo allylsilane 13 and CrCl(2), followed by NaH to effect elimination to the diene 15. A similar sequence was employed to prepare aldehyde 29. In this case aldehyde (S)-1 was converted to the anti,syn-homopropargylic alcohol 20 by treatment with the allenyl indium reagent formed in situ from allenylstannane (P)-2b and InBr(3). Epoxy alcohol 24, prepared from alcohol 20 by the above-described sequence, was reduced with Red-Al to afford diol 25. Protection of the secondary alcohol and oxidation of the primary completed the synthesis of 29. The anti,syn-homopropargylic alcohol 32 was obtained through addition of the allenic indium reagent, from allenylstannane (P)-31, to aldehyde (S)-1. Protection of the derived diol 33 as the p-methoxybenzylidene acetal afforded the third subunit, acetylene 34. Addition of the lithio derivative of 34 to aldehyde 29 gave alcohol 35 with the carbinyl stereochemistry needed for C7 of discodermolide as the major product.

  18. On-road emission characteristics of VOCs from rural vehicles and their ozone formation potential in Beijing, China

    NASA Astrophysics Data System (ADS)

    Yao, Zhiliang; Wu, Bobo; Shen, Xianbao; Cao, Xinyue; Jiang, Xi; Ye, Yu; He, Kebin

    2015-03-01

    This paper is the second in a series of papers aimed at understanding volatile organic compound (VOC) emissions from motor vehicles in Beijing using on-board emission measurements, focusing specifically on rural vehicles (RVs). In this work, 13 RVs, including 6 different 3-wheel (3-W) RVs and 7 different 4-wheel (4-W) RVs, were examined using a portable emissions measurement system (PEMS) as the vehicles were driven on predesigned fixed test routes in rural areas of Beijing. Overall, 50 VOC species were quantified in this study, including 18 alkanes, 5 alkenes, 11 aromatics, 13 carbonyls and 3 other compounds. The average emission factor (EF) of the total VOCs for the 4-W RVs based on the distance traveled was 326.2 ± 129.3 mg/km, which is 2.5 times greater than that of the 3-W RVs. However, the VOC emissions for the 3-W RVs had higher EFs based on their CO2 emissions due to the different fuel economies of the two types of RVs. Formaldehyde, toluene, acetaldehyde, m-xylene, p-xylene, isopentane, benzene, ethylbenzene, n-pentane, 2-methoxy-2-methylpropane and butenal were the dominant VOC species from the RVs, accounting for an average of 68.6% of the total VOC emissions. Overall, the RVs had high proportions of aromatics and carbonyls. The ozone formation potentials (OFPs) were 670.6 ± 227.2 and 1454.1 ± 643.0 mg O3/km for the 3-W and 4-W RVs, respectively, and approximately 60%-70% of the OFP resulted from carbonyls. We estimated that the 3-W and 4-W RVs accounted for approximately 50% and 10%, respectively, of the total OFP caused by diesel vehicles (including diesel trucks and RVs) in Beijing in 2012. Thus, more attention should be given to VOC emissions and their impact on ozone formation.

  19. Formation of volatile compounds during heating of spice paprika (Capsicum annuum) powder.

    PubMed

    Cremer, D R; Eichner, K

    2000-06-01

    Spice paprika (red pepper; Capsicum annuum) is the most cultivated spice worldwide and is used mainly for its color and pungency. However, current research is also focusing on the flavor as an important parameter. This paper deals with the kinetics of the formation of those volatiles that indicate a decrease in spice paprika quality due to Maillard reaction, hydrolytic reactions, and oxidative degradation reactions of lipids such as fatty acids and carotenoids. Spice paprika volatiles were quantitatively analyzed by means of headspace gas chromatography (HS-GC) and solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS). The kinetics of their formation were investigated, and the respective activation energies determined. Strecker aldehyde, acetone, and methanol formation followed a pseudo-zero-order reaction kinetic, and formation of dimethyl sulfide (DMS) was characterized by a first-order kinetic. The activation energies determined were between 86.3 and 101.8 for the Strecker aldehydes acetaldehyde (AA), 2-methylpropanal (2-MP), 3-methylbutanal (3-MB), and 2-methylbutanal (2-MB), 130.7 for acetone, 114.2 for methanol, and 109.7 kJ/mol for DMS. The amounts of Strecker aldehydes formed were correlated to the concentrations of the corresponding free amino acids present in the samples. The formation of hexanal and 6-methyl-5-hepten-2-one in Capsicum annuum during processing was confirmed, and the formation of beta-ionone was probably described for the first time. During heating, the concentration of hexanal increased rapidly. The formation of 6-methyl-5-hepten-2-one confirms that Capsicum annuum fruits contain lycopene.

  20. Bacterial degradation of tert-amyl alcohol proceeds via hemiterpene 2-methyl-3-buten-2-ol by employing the tertiary alcohol desaturase function of the Rieske nonheme mononuclear iron oxygenase MdpJ.

    PubMed

    Schuster, Judith; Schäfer, Franziska; Hübler, Nora; Brandt, Anne; Rosell, Mònica; Härtig, Claus; Harms, Hauke; Müller, Roland H; Rohwerder, Thore

    2012-03-01

    Tertiary alcohols, such as tert-butyl alcohol (TBA) and tert-amyl alcohol (TAA) and higher homologues, are only slowly degraded microbially. The conversion of TBA seems to proceed via hydroxylation to 2-methylpropan-1,2-diol, which is further oxidized to 2-hydroxyisobutyric acid. By analogy, a branched pathway is expected for the degradation of TAA, as this molecule possesses several potential hydroxylation sites. In Aquincola tertiaricarbonis L108 and Methylibium petroleiphilum PM1, a likely candidate catalyst for hydroxylations is the putative tertiary alcohol monooxygenase MdpJ. However, by comparing metabolite accumulations in wild-type strains of L108 and PM1 and in two mdpJ knockout mutants of strain L108, we could clearly show that MdpJ is not hydroxylating TAA to diols but functions as a desaturase, resulting in the formation of the hemiterpene 2-methyl-3-buten-2-ol. The latter is further processed via the hemiterpenes prenol, prenal, and 3-methylcrotonic acid. Likewise, 3-methyl-3-pentanol is degraded via 3-methyl-1-penten-3-ol. Wild-type strain L108 and mdpJ knockout mutants formed isoamylene and isoprene from TAA and 2-methyl-3-buten-2-ol, respectively. It is likely that this dehydratase activity is catalyzed by a not-yet-characterized enzyme postulated for the isomerization of 2-methyl-3-buten-2-ol and prenol. The vitamin requirements of strain L108 growing on TAA and the occurrence of 3-methylcrotonic acid as a metabolite indicate that TAA and hemiterpene degradation are linked with the catabolic route of the amino acid leucine, including an involvement of the biotin-dependent 3-methylcrotonyl coenzyme A (3-methylcrotonyl-CoA) carboxylase LiuBD. Evolutionary aspects of favored desaturase versus hydroxylation pathways for TAA conversion and the possible role of MdpJ in the degradation of higher tertiary alcohols are discussed.

  1. Bacterial Degradation of tert-Amyl Alcohol Proceeds via Hemiterpene 2-Methyl-3-Buten-2-ol by Employing the Tertiary Alcohol Desaturase Function of the Rieske Nonheme Mononuclear Iron Oxygenase MdpJ

    PubMed Central

    Schuster, Judith; Schäfer, Franziska; Hübler, Nora; Brandt, Anne; Rosell, Mònica; Härtig, Claus; Harms, Hauke; Müller, Roland H.

    2012-01-01

    Tertiary alcohols, such as tert-butyl alcohol (TBA) and tert-amyl alcohol (TAA) and higher homologues, are only slowly degraded microbially. The conversion of TBA seems to proceed via hydroxylation to 2-methylpropan-1,2-diol, which is further oxidized to 2-hydroxyisobutyric acid. By analogy, a branched pathway is expected for the degradation of TAA, as this molecule possesses several potential hydroxylation sites. In Aquincola tertiaricarbonis L108 and Methylibium petroleiphilum PM1, a likely candidate catalyst for hydroxylations is the putative tertiary alcohol monooxygenase MdpJ. However, by comparing metabolite accumulations in wild-type strains of L108 and PM1 and in two mdpJ knockout mutants of strain L108, we could clearly show that MdpJ is not hydroxylating TAA to diols but functions as a desaturase, resulting in the formation of the hemiterpene 2-methyl-3-buten-2-ol. The latter is further processed via the hemiterpenes prenol, prenal, and 3-methylcrotonic acid. Likewise, 3-methyl-3-pentanol is degraded via 3-methyl-1-penten-3-ol. Wild-type strain L108 and mdpJ knockout mutants formed isoamylene and isoprene from TAA and 2-methyl-3-buten-2-ol, respectively. It is likely that this dehydratase activity is catalyzed by a not-yet-characterized enzyme postulated for the isomerization of 2-methyl-3-buten-2-ol and prenol. The vitamin requirements of strain L108 growing on TAA and the occurrence of 3-methylcrotonic acid as a metabolite indicate that TAA and hemiterpene degradation are linked with the catabolic route of the amino acid leucine, including an involvement of the biotin-dependent 3-methylcrotonyl coenzyme A (3-methylcrotonyl-CoA) carboxylase LiuBD. Evolutionary aspects of favored desaturase versus hydroxylation pathways for TAA conversion and the possible role of MdpJ in the degradation of higher tertiary alcohols are discussed. PMID:22194447

  2. Antipsychotic profiles of TASP0443294, a novel and orally active positive allosteric modulator of metabotropic glutamate 2 receptor.

    PubMed

    Hikichi, Hirohiko; Hiyoshi, Tetsuaki; Marumo, Toshiyuki; Tomishima, Yasumitsu; Kaku, Ayaka; Iida, Izumi; Urabe, Hiroki; Tamita, Tomoko; Yasuhara, Akito; Karasawa, Jun-ichi; Chaki, Shigeyuki

    2015-03-01

    Glutamatergic dysfunction has been implicated in psychiatric disorders such as schizophrenia. The stimulation of metabotropic glutamate (mGlu) 2 receptor has been shown to be effective in a number of animal models of schizophrenia. In this study, we investigated the antipsychotic profiles of (2S)-5-methyl-2-{[4-(1,1,1-trifluoro-2-methylpropan-2-yl)phenoxy]methyl}-2,3-dihydroimidazo[2,1-b][1,3]oxazole-6-carboxamide (TASP0443294), a newly synthesized positive allosteric modulator of the mGlu2 receptor. TASP0443294 potentiated the response of human mGlu2 and rat mGlu2 receptors to glutamate with EC50 values of 277 and 149 nM, respectively, without affecting the glutamate response of human mGlu3 receptor. TASP0443294 was distributed in the brain and cerebrospinal fluid after peroral administration in rats. The peroral administration of TASP0443294 inhibited methamphetamine-induced hyperlocomotion in rats, which was attenuated by an mGlu2/3 receptor antagonist, and improved social memory impairment induced by 5R,10S-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801) in rats. Furthermore, TASP0443294 reduced the ketamine-induced basal gamma hyperactivity in the prefrontal cortex and suppressed rapid eye movement (REM) sleep in rats. These findings indicate that TASP0443294 is an mGlu2 receptor positive allosteric modulator with antipsychotic activity, and that the suppression of aberrant gamma oscillations and REM sleep could be considered as neurophysiological biomarkers for TASP0443294. PMID:25837934

  3. Oxytetracycline recovery from aqueous media using computationally designed molecularly imprinted polymers.

    PubMed

    Rodríguez-Dorado, Rosalía; Carro, Antonia M; Chianella, Iva; Karim, Kal; Concheiro, Angel; Lorenzo, Rosa A; Piletsky, Sergey; Alvarez-Lorenzo, Carmen

    2016-09-01

    Polymers for recovery/removal of the antimicrobial agent oxytetracycline (OTC) from aqueous media were developed with use of computational design and molecular imprinting. 2-Hydroxyethyl methacrylate, 2-acrylamide-2-methylpropane sulfonic acid (AMPS), and mixtures of the two were chosen according to their predicted affinity for OTC and evaluated as functional monomers in molecularly imprinted polymers and nonimprinted polymers. Two levels of AMPS were tested. After bulk polymerization, the polymers were crushed into particles (200-1000 μm). Pressurized liquid extraction was implemented for template removal with a low amount of methanol (less than 20 mL in each extraction) and a few extractions (12-18 for each polymer) in a short period (20 min per extraction). Particle size distribution, microporous structure, and capacity to rebind OTC from aqueous media were evaluated. Adsorption isotherms obtained from OTC solutions (30-110 mg L(-1)) revealed that the polymers prepared with AMPS had the highest affinity for OTC. The uptake capacity depended on the ionic strength as follows: purified water > saline solution (0.9 % NaCl) > seawater (3.5 % NaCl). Polymer particles containing AMPS as a functional monomer showed a remarkable ability to clean water contaminated with OTC. The usefulness of the stationary phase developed for molecularly imprinted solid-phase extraction was also demonstrated. Graphical Abstract Selection of functional monomers by molecular modeling renders polymer networks suitable for removal of pollutants from contaminated aqueous environments, under either dynamic or static conditions. PMID:27488280

  4. Kinetics and products of the OH radical-initiated reaction of 3-methyl-2-butenal.

    PubMed

    Tuazon, Ernesto C; Aschmann, Sara M; Nishino, Noriko; Arey, Janet; Atkinson, Roger

    2005-06-01

    Kinetics and products of the gas-phase reaction of OH radicals with 3-methyl-2-butenal [(CH3)2C=CHCHO] have been investigated at room temperature and atmospheric pressure of air. Using a relative rate method with methacrolein as the reference compound, a rate constant for the reaction of OH radicals with 3-methyl-2-butenal of (6.21 +/- 0.18) x 10(-11) cm3 molecule(-1) s(-1) at 296 +/- 2 K was measured, where the indicated error does not include the uncertainty in the rate constant for the methacrolein reference compound. Products of this reaction were investigated using in situ Fourier transform infrared (FT-IR) spectroscopy and solid phase microextraction (SPME) fibers coated with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine for on-fiber derivatization of carbonyl compounds, with subsequent thermal desorption and analysis by gas chromatography. The products observed and the molar formation yields were: glyoxal, 40 +/- 3%; acetone, 74 +/- 6%; 2-hydroxy-2-methylpropanal, 4.6 +/- 0.7%; CO2, 39% initially, decreasing to 30% at greater extents of reaction; peroxyacyl nitrate(s) [RC(O)OONO2], 5-8%, increasing with the extent of reaction and with the sum of the CO2 and RC(O)OONO2 yields being 38 +/- 6%; and organic nitrates [RONO2], 8.5 +/- 2.3%. The formation of these products is readily explained by a reaction mechanism based on those previously formulated for the corresponding reactions of the alpha,beta-unsaturated aldehydes acrolein, crotonaldehyde and methacrolein. Based on the mechanism proposed, at room temperature H-atom abstraction from the CHO group accounts for 40 +/- 6% of the overall reaction, and OH radical addition to the carbon atoms of the C=C bond accounts for 53 +/- 4% of the overall reaction. Hence 93 +/- 8% of the reaction products and pathways are accounted for.

  5. Excited singlet molecular O2 (1Δg) is generated enzymatically from excited carbonyls in the dark

    PubMed Central

    Mano, Camila M.; Prado, Fernanda M.; Massari, Júlio; Ronsein, Graziella E.; Martinez, Glaucia R.; Miyamoto, Sayuri; Cadet, Jean; Sies, Helmut; Medeiros, Marisa H. G.; Bechara, Etelvino J. H.; Di Mascio, Paolo

    2014-01-01

    In mammalian tissues, ultraweak chemiluminescence arising from biomolecule oxidation has been attributed to the radiative deactivation of singlet molecular oxygen [O2 (1Δg)] and electronically excited triplet carbonyl products involving dioxetane intermediates. Herein, we describe evidence of the generation of O2 (1Δg) in aqueous solution via energy transfer from excited triplet acetone. This involves thermolysis of 3,3,4,4-tetramethyl-1,2-dioxetane, a chemical source, and horseradish peroxidase-catalyzed oxidation of 2-methylpropanal, as an enzymatic source. Both sources of excited carbonyls showed characteristic light emission at 1,270 nm, directly indicative of the monomolecular decay of O2 (1Δg). Indirect analysis of O2 (1Δg) by electron paramagnetic resonance using the chemical trap 2,2,6,6-tetramethylpiperidine showed the formation of 2,2,6,6-tetramethylpiperidine-1-oxyl. Using [18O]-labeled triplet, ground state molecular oxygen [18O2 (3Σg-)], chemical trapping of 18O2 (1Δg) with disodium salt of anthracene-9,10-diyldiethane-2,1-diyl disulfate yielding the corresponding double-[18O]-labeled 9,10-endoperoxide, was detected through mass spectrometry. This corroborates formation of O2 (1Δg). Altogether, photoemission and chemical trapping studies clearly demonstrate that chemically and enzymatically nascent excited carbonyl generates 18O2 (1Δg) by triplet-triplet energy transfer to ground state oxygen O2 (3Σg−), and supports the long formulated hypothesis of O2 (1Δg) involvement in physiological and pathophysiological events that might take place in tissues in the absence of light. PMID:25087485

  6. Selective determination of pharmaceuticals and illicit drugs in wastewaters using a novel strong cation-exchange solid-phase extraction combined with liquid chromatography-tandem mass spectrometry.

    PubMed

    Gilart, Núria; Cormack, P A G; Marcé, Rosa Maria; Fontanals, Núria; Borrull, Francesc

    2014-01-17

    In this study, two materials are presented with strong cation-exchange (SCX) behaviour synthesised by two different approaches and then crushed for their application as sorbents for solid-phase extraction (SPE) to extract a group of pharmaceuticals and illicit drugs selectively from wastewater samples. The first SCX polymer was obtained by copolymerisation of three monomers: 2-acrylamido-2-methylpropane sulphonic acid (AMPSA), 2-hydroxyethyl methacrylate (HEMA) and pentaerythritol triacrylate (PETRA), while the second was obtained by post-modification with sulphuric acid (H2SO4) of a copolymer based on HEMA and divinylbenzene (DVB). After their syntheses, both polymers were evaluated as SPE sorbents, with all parameters affecting SPE being optimised, such as sample pH, washing and elution solvents and volumes. Thanks to the sulphonic groups present in the structure of the polymers, all of the compounds with basic functionalities were retained on the sorbents after the washing step, removing the acidic analytes and other interfering compounds, providing successful results in terms of ion suppression/enhancement (-12% and 21%) when wastewater samples were analysed. However, AMPSA/HEMA/PETRA (20/60/20) failed to retain the analytes after loading wastewater samples (25 or 50mL), decreasing analyte recovery values significantly, whereas the sulphonated HEMA/DVB (50/50) enabled good SPE performance with recovery values between 70% and 98%, except for ranitidine and EDDP (39% and 43%, respectively). Therefore, this polymer was selected for further method validation and quantification of wastewater samples, providing low method detection limits (MDLs) in this matrix (from 2 to 40ngL(-1)). Finally, most of the studied compounds were detected and quantified in wastewater samples, especially atenolol, ranitidine, cocaine and its metabolite benzoylecgonine. PMID:24369996

  7. Indigenous Georgian Wine-Associated Yeasts and Grape Cultivars to Edit the Wine Quality in a Precision Oenology Perspective

    PubMed Central

    Vigentini, Ileana; Maghradze, David; Petrozziello, Maurizio; Bonello, Federica; Mezzapelle, Vito; Valdetara, Federica; Failla, Osvaldo; Foschino, Roberto

    2016-01-01

    In Georgia, one of the most ancient vine-growing environment, the homemade production of wine is still very popular in every rural family and spontaneous fermentation of must, without addition of chemical preservatives, is the norm. The present work investigated the yeast biodiversity in five Georgian areas (Guria, Imereti, Kakheti, Kartli, Ratcha-Lechkhumi) sampling grapes and wines from 22 different native cultivars, in 26 vineyards and 19 family cellars. One hundred and eighty-two isolates were ascribed to 15 different species by PCR-ITS and RFLP, and partial sequencing of D1/D2 domain 26S rDNA gene. Metschnikowia pulcherrima (F’ = 0.56, I’ = 0.32), Hanseniaspora guilliermondii (F’ = 0.49, I’ = 0.27), and Cryptococcus flavescens (F’ = 0.31, I’ = 0.11) were the dominant yeasts found on grapes, whereas Saccharomyces cerevisiae showed the highest prevalence into wine samples. Seventy four isolates with fermentative potential were screened for oenological traits such as ethanol production, resistance to SO2, and acetic acid, glycerol and H2S production. Three yeast strains (Kluyveromyces marxianus UMY207, S. cerevisiae UMY255, Torulaspora delbrueckii UMY196) were selected and separately inoculated in vinifications experiments at a Georgian cellar. Musts were prepared from healthy grapes of local varieties, Goruli Mtsvane (white berry cultivar) and Saperavi (black berry cultivar). Physical (°Brix) and microbial analyses (plate counts) were performed to monitor the fermentative process. The isolation of indigenous S. cerevisiae yeasts beyond the inoculated strains indicated that a co-presence occurred during the vinification tests. Results from quantitative GC-FID analysis of volatile compounds revealed that the highest amount of fermentation flavors, such as 4-ethoxy-4-oxobutanoic acid (monoethyl succinate), 2-methylpropan-1-ol, ethyl 2-hydroxypropanoate, and 2-phenylethanol, were significantly more produced in fermentation conducted in Saperavi variety

  8. Thermochemical Properties Enthalpy, Entropy, and Heat Capacity of C1-C4 Fluorinated Hydrocarbons: Fluorocarbon Group Additivity.

    PubMed

    Wang, Heng; Castillo, Álvaro; Bozzelli, Joseph W

    2015-07-23

    Enthalpies of formation for 14 C2–C4 fluorinated hydrocarbons were calculated with nine popular ab initio and density functional theory methods: B3LYP, CBS-QB3, CBS-APNO, M06, M06-2X, ωB97X, G4, G4(MP2)-6X, and W1U via several series of isodesmic reactions. The recommended ideal gas phase ΔHf298° (kcal mol(–1)) values calculated in this study are the following: −65.4 for CH3CH2F; −70.2 for CH3CH2CH2F; −75.3 for CH3CHFCH3; −75.2 for CH3CH2CH2CH2F; −80.3 for CH3CHFCH2CH3; −108.1 for CH2F2; −120.9 for CH3CHF2; −125.8 for CH3CH2CHF2; −133.3 for CH3CF2CH3; −166.7 for CHF3; −180.5 for CH3CF3; −185.5 for CH3CH2CF3; −223.2 for CF4; and −85.8 for (CH3)3CF. Entropies (S298° in cal mol(–1) K(–1)) were estimated using B3LYP/6-31+G(d,p) computed frequencies and geometries. Rotational barriers were determined and hindered internal rotational contributions for S298°, and Cp(T) were calculated using the rigid rotor harmonic oscillator approximation, with direct integration over energy levels of the intramolecular rotation potential energy curve. Thermochemical properties for the fluorinated carbon groups C/C/F/H2, C/C2/F/H, C/C/F2/H, C/C2/F2, and C/C/F3 were derived from the above target fluorocarbons. Previously published enthalpies and groups for 1,2-difluoroethane, 1,1,2-trifluoroethane, 1,1,2,2-tetrafluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,1,2,2-pentafluoroethane, 2-fluoro-2-methylpropane that were previously determined via work reaction schemes are revised using updated reference species values. Standard deviations are compared for the calculation methods.

  9. Optimisation and validation of a HS-SPME-GC-IT/MS method for analysis of carbonyl volatile compounds as biomarkers in human urine: Application in a pilot study to discriminate individuals with smoking habits.

    PubMed

    Calejo, Isabel; Moreira, Nathalie; Araújo, Ana Margarida; Carvalho, Márcia; Bastos, Maria de Lourdes; de Pinho, Paula Guedes

    2016-02-01

    A new and simple analytical approach consisting of an automated headspace solid-phase microextraction (HS-SPME) sampler coupled to gas chromatography-ion trap/mass spectrometry detection (GC-IT/MS) with a prior derivatization step with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) was developed to detect volatile carbonyl metabolites with low molecular weights in human urine. A central composite design (CCD) was used to optimise the PFBHA concentration and extraction conditions that affect the efficiency of the SPME procedure. With a sample volume of 1 mL, optimal conditions were achieved by adding 300 mg/L of PFBHA and allowing the sample to equilibrate for 6 min at 62°C and then extracting the samples for 51 min at the same temperature, using a divinylbenzene/polydimethylsiloxane (DVB/PDMS) fibre. The method allowed the simultaneous identification and quantification of 44 carbonyl compounds consisting of aldehydes, dialdehydes, heterocyclic aldehydes and ketones. The method was validated with regards to the linearity, inter- and intra-day precision and accuracy. The detection limits ranged from 0.009 to 0.942 ng/mL, except for 4-hydroxy-2-nonenal (15 ng/mL), and the quantification limits varied from 0.029 to 1.66 ng/mL, except for butanal (2.78 ng/mL), 2-butanone (2.67 ng/mL), 4-heptanone (3.14 ng/mL) and 4-hydroxy-2-nonenal (50.0 ng/mL). The method accuracy was satisfactory, with recoveries ranging from 90 to 107%. The proof of applicability of the methodology was performed in a pilot target analysis of urine samples obtained from 18 healthy smokers and 18 healthy non-smokers (control group). Chemometric supervised analysis was performed using the volatile patterns acquired for these samples and clearly showed the potential of the volatile carbonyl profiles to discriminate urine from smoker and non-smoker subjects. 5-Methyl-2-furfural (p<0.0001), 2-methylpropanal, nonanal and 2-methylbutanal (p<0.05) were identified as potentially useful

  10. Comparison of different real time VOC measurement techniques in a ponderosa pine forest

    NASA Astrophysics Data System (ADS)

    Kaser, L.; Karl, T.; Schnitzhofer, R.; Graus, M.; Herdlinger-Blatt, I. S.; DiGangi, J. P.; Sive, B.; Turnipseed, A.; Hornbrook, R. S.; Zheng, W.; Flocke, F. M.; Guenther, A.; Keutsch, F. N.; Apel, E.; Hansel, A.

    2013-03-01

    Volatile organic compound (VOC) mixing ratios measured by five independent instruments are compared at a forested site dominated by ponderosa pine (Pinus Ponderosa) during the BEACHON-ROCS field study in summer 2010. The instruments included a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-TOF-MS), a Proton Transfer Reaction Quadrupole Mass Spectrometer (PTR-MS), a Fast Online Gas-Chromatograph coupled to a Mass Spectrometer (GC/MS; TOGA), a Thermal Dissociation Chemical Ionization Mass Spectrometer (PAN-CIMS) and a Fiber Laser-Induced Fluorescence Instrument (FILIF). The species discussed in this comparison include the most important biogenic VOCs and a selected suite of oxygenated VOCs that are thought to dominate the VOC reactivity at this particular site as well as typical anthropogenic VOCs that showed low mixing ratios at this site. Good agreement was observed for methanol, the sum of the oxygenated hemiterpene 2-methyl-3-buten-2-ol (MBO) and the hemiterpene isoprene, acetaldehyde, the sum of acetone and propanal, benzene and the sum of methyl ethyl ketone (MEK) and butanal. Measurements of the above VOCs conducted by different instruments agree within 20%. The ability to differentiate the presence of toluene and cymene by PTR-TOF-MS is tested based on a comparison with GC-MS measurements, suggesting a study-average relative contribution of 74% for toluene and 26% for cymene. Similarly, 2-hydroxy-2-methylpropanal (HMPR) is found to interfere with the sum of methyl vinyl ketone and methacrolein (MVK + MAC) using PTR-(TOF)-MS at this site. A study-average relative contribution of 85% for MVK + MAC and 15% for HMPR was determined. The sum of monoterpenes measured by PTR-MS and PTR-TOF-MS was generally 20-25% higher than the sum of speciated monoterpenes measured by TOGA, which included α-pinene, β-pinene, camphene, carene, myrcene, limonene, cineole as well as other terpenes. However, this difference is consistent throughout the study, and

  11. Comparison of different real time VOC measurement techniques in a ponderosa pine forest

    NASA Astrophysics Data System (ADS)

    Kaser, L.; Karl, T.; Schnitzhofer, R.; Graus, M.; Herdlinger-Blatt, I. S.; DiGangi, J. P.; Sive, B.; Turnipseed, A.; Hornbrook, R. S.; Zheng, W.; Flocke, F. M.; Guenther, A.; Keutsch, F. N.; Apel, E.; Hansel, A.

    2012-10-01

    Volatile organic compound (VOC) mixing ratios measured by five independent instruments are compared at a forested site dominated by ponderosa pine (Pinus Ponderosa) during the BEACHON-ROCS field study in summer 2010. The instruments included a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-TOF-MS), a Proton Transfer Reaction Quadrupole Mass Spectrometer (PTR-MS), a Fast Online Gas-Chromatograph coupled to a Mass Spectrometer (GC/MS; TOGA), a Thermal Dissociation Chemical Ionization Mass Spectrometer (PAN-CIMS) and a Fiber Laser-Induced Fluorescence Instrument (FILIF). The species discussed in this comparison include the most important biogenic VOCs and a selected suite of oxygenated VOCs that are thought to dominate the VOC reactivity at this particular site as well as typical anthropogenic VOCs that showed low mixing ratios at this site. Good agreement was observed for methanol, the sum of the oxygenated hemiterpene 2-methyl-3-buten-2-ol (MBO) and the hemiterpene isoprene, acetaldehyde, the sum of acetone and propanal, benzene and the sum of methyl ethyl ketone (MEK) and butanal. Measurements of the above VOCs conducted by different instruments agree within 20%. The ability to differentiate the presence of toluene and cymene by PTR-TOF-MS is tested based on a comparison with GC-MS measurements, suggesting a study-average relative contribution of 74% for toluene and 26% for cymene. Similarly, 2-hydroxy-2-methylpropanal (HMPR) is found to interfere with the sum of methyl vinyl ketone and methacrolein (MVK+MAC) using PTR-(TOF)-MS at this site. A study-average relative contribution of 85% for MVK+MAC and 15% for HMPR was determined. The sum of monoterpenes measured by PTR-MS and PTR-TOF-MS was generally 20-25% higher than the sum of speciated monoterpenes measured by TOGA, which included α-pinene, β-pinene, camphene, carene, myrcene, limonene, cineole as well as other terpenes. However, this difference is consistent throughout the study, and likely

  12. Biosynthesis of the cyanogenic glucosides linamarin and lotaustralin in cassava: isolation, biochemical characterization, and expression pattern of CYP71E7, the oxime-metabolizing cytochrome P450 enzyme.

    PubMed

    Jørgensen, Kirsten; Morant, Anne Vinther; Morant, Marc; Jensen, Niels Bjerg; Olsen, Carl Erik; Kannangara, Rubini; Motawia, Mohammed Saddik; Møller, Birger Lindberg; Bak, Søren

    2011-01-01

    Cassava (Manihot esculenta) is a eudicotyledonous plant that produces the valine- and isoleucine-derived cyanogenic glucosides linamarin and lotaustralin with the corresponding oximes and cyanohydrins as key intermediates. CYP79 enzymes catalyzing amino acid-to-oxime conversion in cyanogenic glucoside biosynthesis are known from several plants including cassava. The enzyme system converting oxime into cyanohydrin has previously only been identified in the monocotyledonous plant great millet (Sorghum bicolor). Using this great millet CYP71E1 sequence as a query in a Basic Local Alignment Search Tool-p search, a putative functional homolog that exhibited an approximately 50% amino acid sequence identity was found in cassava. The corresponding full-length cDNA clone was obtained from a plasmid library prepared from cassava shoot tips and was assigned CYP71E7. Heterologous expression of CYP71E7 in yeast afforded microsomes converting 2-methylpropanal oxime (valine-derived oxime) and 2-methylbutanal oxime (isoleucine-derived oxime) to the corresponding cyanohydrins, which dissociate into acetone and 2-butanone, respectively, and hydrogen cyanide. The volatile ketones were detected as 2.4-dinitrophenylhydrazone derivatives by liquid chromatography-mass spectrometry. A K(S) of approximately 0.9 μm was determined for 2-methylbutanal oxime based on substrate-binding spectra. CYP71E7 exhibits low specificity for the side chain of the substrate and catalyzes the conversion of aliphatic and aromatic oximes with turnovers of approximately 21, 17, 8, and 1 min(-1) for the oximes derived from valine, isoleucine, tyrosine, and phenylalanine, respectively. A second paralog of CYP71E7 was identified by database searches and showed approximately 90% amino acid sequence identity. In tube in situ polymerase chain reaction showed that in nearly unfolded leaves, the CYP71E7 paralogs are preferentially expressed in specific cells in the endodermis and in most cells in the first cortex

  13. Light-scattering study of polyelectrolyte complex formation between anionic and cationic nanogels in an aqueous salt-free system.

    PubMed

    Miyake, Masafumi; Ogawa, Kazuyoshi; Kokufuta, Etsuo

    2006-08-15

    We studied complex formation in an aqueous salt-free system (pH approximately 3 and at 25 degrees C) between nanogel particles having opposite charges. Anionic gel (AG) and cationic gel (CG) particles consist of lightly cross-linked N-isopropylacrylamide (NIPA) copolymers with 2-acrylamido-2-methylpropane sulfonic acid and with 1-vinylimidazole, respectively. The number of charges per particle was -4490 for AG and +20 300 for CG, as estimated from their molar masses (3.33 MD for AG and 11.7 MD for CG) by static light scattering (SLS) and their charge densities (1.35 mmol/g for AG and 1.74 mmol/g for CG) by potentiometric titration. The complexes were formed through the addition of AG to CG and vice versa using a turbidimetric titration technique. At the endpoint of the titration, the aggregate formed was a complex based upon stoichiometric charge neutralization: CG(n)()(+) + xAG(m)()(-) --> CG(n)()(+) (AG(m)()(-))(x)() where x = (n)()/(m)(). At different stages of the titration before the endpoint, the resulting complexes were examined in detail using dynamic light scattering, SLS, and electrophoretic light scattering (ELS). The main results are summarized as follows: (i) When AG with a hydrodynamic radius (R(h)) of 119 nm is added to CG (R(h) approximately 156 nm), the (R(h)) of the complex size decreases from 156 to 80 nm. (ii) In contrast to this (R(h)) change, the molar mass increases from 11.7 MD to 24 MD with increasing amounts of added AG. (iii) Upon addition of CG to AG, the complex formed has the same size ((R(h)) approximately 80 nm) and the same molar mass (55 +/- 2.5 MD) until 55 +/- 5% of AG has been consumed in the complexation. To understand these results, we used the following two models: the random model (RM), in which the added AG particles uniformly bind to all of the CG particles in the system via a strong electrostatic attraction, and the all-or-none model (AONM), in which part of the AG particles in the system preferably bind to the added CG

  14. Optimisation and validation of a HS-SPME-GC-IT/MS method for analysis of carbonyl volatile compounds as biomarkers in human urine: Application in a pilot study to discriminate individuals with smoking habits.

    PubMed

    Calejo, Isabel; Moreira, Nathalie; Araújo, Ana Margarida; Carvalho, Márcia; Bastos, Maria de Lourdes; de Pinho, Paula Guedes

    2016-02-01

    A new and simple analytical approach consisting of an automated headspace solid-phase microextraction (HS-SPME) sampler coupled to gas chromatography-ion trap/mass spectrometry detection (GC-IT/MS) with a prior derivatization step with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) was developed to detect volatile carbonyl metabolites with low molecular weights in human urine. A central composite design (CCD) was used to optimise the PFBHA concentration and extraction conditions that affect the efficiency of the SPME procedure. With a sample volume of 1 mL, optimal conditions were achieved by adding 300 mg/L of PFBHA and allowing the sample to equilibrate for 6 min at 62°C and then extracting the samples for 51 min at the same temperature, using a divinylbenzene/polydimethylsiloxane (DVB/PDMS) fibre. The method allowed the simultaneous identification and quantification of 44 carbonyl compounds consisting of aldehydes, dialdehydes, heterocyclic aldehydes and ketones. The method was validated with regards to the linearity, inter- and intra-day precision and accuracy. The detection limits ranged from 0.009 to 0.942 ng/mL, except for 4-hydroxy-2-nonenal (15 ng/mL), and the quantification limits varied from 0.029 to 1.66 ng/mL, except for butanal (2.78 ng/mL), 2-butanone (2.67 ng/mL), 4-heptanone (3.14 ng/mL) and 4-hydroxy-2-nonenal (50.0 ng/mL). The method accuracy was satisfactory, with recoveries ranging from 90 to 107%. The proof of applicability of the methodology was performed in a pilot target analysis of urine samples obtained from 18 healthy smokers and 18 healthy non-smokers (control group). Chemometric supervised analysis was performed using the volatile patterns acquired for these samples and clearly showed the potential of the volatile carbonyl profiles to discriminate urine from smoker and non-smoker subjects. 5-Methyl-2-furfural (p<0.0001), 2-methylpropanal, nonanal and 2-methylbutanal (p<0.05) were identified as potentially useful

  15. Singlet molecular oxygen generated in dark biological process.

    PubMed

    Di Mascio, Paolo; Medeiros, Marisa H G

    2014-10-01

    Ultraweak chemiluminescence arising from biomolecules oxidation has been attributed to the radiative deactivation of singlet molecular oxygen [(1)O2] and electronically excited triplet carbonyl products involving dioxetane intermediates. As examples, we will discuss the generation of (1)O2 from lipid hydroperoxides, which involves a cyclic mechanism from a linear tetraoxide intermediate. The generation of (1)O2 in aqueous solution via energy transfer from the excited triplet acetone arising from the thermodecomposition of dioxetane a chemical source, and horseradish peroxidase-catalyzed oxidation of 2-methylpropanal, as an enzymatic source, will also be discussed. The approach used to unequivocally demonstrate the generation of (1)O2 in these reactions is the use of (18)O-labeled hydroperoxide / triplet dioxygen ((18)[(3)O2]), the detection of labeled compounds by HPLC coupled to tandem mass spectrometry (HPLC-MS/MS) and the direct spectroscopic detection and characterization of (1)O2 light emission. Characteristic light emission at 1,270nm, corresponding to the singlet delta state monomolecular decay was observed. Using(18)[(3)O2], we observed the formation of (18)O-labeled (1)O2 ((18)[(1)O2]) by the chemical trapping of (18)[(1)O2]with the anthracene-9,10-diyldiethane-2,1-diyl disulfate disodium salt (EAS) and detected the corresponding (18)O-labeled EAS endoperoxide usingHPLC-MS/MS. The combined use of the thermolysis of a water-soluble naphthalene endoperoxide as a generator of (18)O labeled (1)O2 and the sensitivity of HPLC-MS/MS allowed the study of (1)O2reactivity toward biomolecules. Photoemission properties and chemical trapping clearly demonstrate that the production of hydroperoxide and excited carbonyls generates (18)[(1)O2], and points to the involvement of (1)O2 in physiological and pathophysiological mechanism. Supported by FAPESP (2012/12663-1), CAPES, INCT Redoxoma (FAPESP/CNPq/CAPES; 573530/2008-4), NAP Redoxoma (PRPUSP; 2011.1.9352.1.8), CEPID

  16. Biosynthesis of the Cyanogenic Glucosides Linamarin and Lotaustralin in Cassava: Isolation, Biochemical Characterization, and Expression Pattern of CYP71E7, the Oxime-Metabolizing Cytochrome P450 Enzyme1[OA

    PubMed Central

    Jørgensen, Kirsten; Morant, Anne Vinther; Morant, Marc; Jensen, Niels Bjerg; Olsen, Carl Erik; Kannangara, Rubini; Motawia, Mohammed Saddik; Møller, Birger Lindberg; Bak, Søren

    2011-01-01

    Cassava (Manihot esculenta) is a eudicotyledonous plant that produces the valine- and isoleucine-derived cyanogenic glucosides linamarin and lotaustralin with the corresponding oximes and cyanohydrins as key intermediates. CYP79 enzymes catalyzing amino acid-to-oxime conversion in cyanogenic glucoside biosynthesis are known from several plants including cassava. The enzyme system converting oxime into cyanohydrin has previously only been identified in the monocotyledonous plant great millet (Sorghum bicolor). Using this great millet CYP71E1 sequence as a query in a Basic Local Alignment Search Tool-p search, a putative functional homolog that exhibited an approximately 50% amino acid sequence identity was found in cassava. The corresponding full-length cDNA clone was obtained from a plasmid library prepared from cassava shoot tips and was assigned CYP71E7. Heterologous expression of CYP71E7 in yeast afforded microsomes converting 2-methylpropanal oxime (valine-derived oxime) and 2-methylbutanal oxime (isoleucine-derived oxime) to the corresponding cyanohydrins, which dissociate into acetone and 2-butanone, respectively, and hydrogen cyanide. The volatile ketones were detected as 2.4-dinitrophenylhydrazone derivatives by liquid chromatography-mass spectrometry. A KS of approximately 0.9 μm was determined for 2-methylbutanal oxime based on substrate-binding spectra. CYP71E7 exhibits low specificity for the side chain of the substrate and catalyzes the conversion of aliphatic and aromatic oximes with turnovers of approximately 21, 17, 8, and 1 min−1 for the oximes derived from valine, isoleucine, tyrosine, and phenylalanine, respectively. A second paralog of CYP71E7 was identified by database searches and showed approximately 90% amino acid sequence identity. In tube in situ polymerase chain reaction showed that in nearly unfolded leaves, the CYP71E7 paralogs are preferentially expressed in specific cells in the endodermis and in most cells in the first cortex cell

  17. Indigenous Georgian Wine-Associated Yeasts and Grape Cultivars to Edit the Wine Quality in a Precision Oenology Perspective.

    PubMed

    Vigentini, Ileana; Maghradze, David; Petrozziello, Maurizio; Bonello, Federica; Mezzapelle, Vito; Valdetara, Federica; Failla, Osvaldo; Foschino, Roberto

    2016-01-01

    In Georgia, one of the most ancient vine-growing environment, the homemade production of wine is still very popular in every rural family and spontaneous fermentation of must, without addition of chemical preservatives, is the norm. The present work investigated the yeast biodiversity in five Georgian areas (Guria, Imereti, Kakheti, Kartli, Ratcha-Lechkhumi) sampling grapes and wines from 22 different native cultivars, in 26 vineyards and 19 family cellars. One hundred and eighty-two isolates were ascribed to 15 different species by PCR-ITS and RFLP, and partial sequencing of D1/D2 domain 26S rDNA gene. Metschnikowia pulcherrima (F' = 0.56, I' = 0.32), Hanseniaspora guilliermondii (F' = 0.49, I' = 0.27), and Cryptococcus flavescens (F' = 0.31, I' = 0.11) were the dominant yeasts found on grapes, whereas Saccharomyces cerevisiae showed the highest prevalence into wine samples. Seventy four isolates with fermentative potential were screened for oenological traits such as ethanol production, resistance to SO2, and acetic acid, glycerol and H2S production. Three yeast strains (Kluyveromyces marxianus UMY207, S. cerevisiae UMY255, Torulaspora delbrueckii UMY196) were selected and separately inoculated in vinifications experiments at a Georgian cellar. Musts were prepared from healthy grapes of local varieties, Goruli Mtsvane (white berry cultivar) and Saperavi (black berry cultivar). Physical (°Brix) and microbial analyses (plate counts) were performed to monitor the fermentative process. The isolation of indigenous S. cerevisiae yeasts beyond the inoculated strains indicated that a co-presence occurred during the vinification tests. Results from quantitative GC-FID analysis of volatile compounds revealed that the highest amount of fermentation flavors, such as 4-ethoxy-4-oxobutanoic acid (monoethyl succinate), 2-methylpropan-1-ol, ethyl 2-hydroxypropanoate, and 2-phenylethanol, were significantly more produced in fermentation conducted in Saperavi variety inoculated

  18. A Unique Equation to Estimate Flash Points of Selected Pure Liquids Application to the Correction of Probably Erroneous Flash Point Values

    NASA Astrophysics Data System (ADS)

    Catoire, Laurent; Naudet, Valérie

    2004-12-01

    several flash points have been reported erroneously, whatever the reason, in one or several reference compilations. In the following lists, the currently accepted flash points for bold compounds err, or probably err, on the hazardous side by at least 10 °C and for the nonbolded compounds, the currently accepted flash points err, or probably err, on the nonhazardous side by at least 10 °C: bicyclohexyl, sec-butylamine, tert-butylamine, 2-cyclohexen-1-one, ethanethiol, 1,3-cyclohexadiene, 1,4-pentadiene, methyl formate, acetonitrile, cinnamaldehyde, 1-pentanol, diethylene glycol, diethyl fumarate, diethyl phthalate, trimethylamine, dimethylamine, 1,6-hexanediol, propylamine, methanethiol, ethylamine, bromoethane, 1-bromopropane, tert-butylbenzene, 1-chloro-2-methylpropane, diacetone alcohol, diethanolamine, 2-ethylbutanal, and formic acid. For some other compounds, no other data than the currently accepted flash points are available. Therefore, it cannot be assessed that these flash point data are erroneous but it can be stated that they are probably erroneous. At least, they need experimental re-examination. They are probably erroneous by at least 15 °C: 1,3-cyclopentadiene, di-tert-butyl sulfide, dimethyl ether, dipropyl ether, 4-heptanone, bis(2-chloroethyl)ether, 1-decanol, 1-phenyl-1-butanone, furan, ethylcyclopentane, 1-heptanethiol, 2,5-hexanediol, 3-hexanone, hexanoic acid methyl ester, 4-methyl-1,3-pentadiene, propanoyl chloride, tetramethylsilane, thiacyclopentane, 1-chloro-2-methyl-1-propene, trans-1,3-pentadiene, 2,3-dimethylheptane, triethylenetetramine, methylal, N-ethylisopropylamine, 3-methyl-2-pentene, and 2,3-dimethyl-1-butene.