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  • 1
    Electronic Resource
    Electronic Resource
    Calorimetric determination of the enthalpy of ionization of oxidized and reduced horse heart cytochrome c (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 899-911 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The heats of ionization of protons, ΔHi, of oxidized and reduced horse heart cytochrome c in 0.15M KCl at 20°C were determined using a titration calorimeter which simultaneously afforded the potentiometric titration curve. Reproducibility of the thermal titrations is within 2%, and evaluation of the heats observed after the heat loss corrections is estimated to be within 5%. A single titration of oxidized cytochrome c from pH 11 to 3 is in excellent agreement with the thermal titration of this protein obtained with flow calorimetry. The thermal titration, however, is not reversible, due in part to the loss of titratable group(s) in this pH region and to the heat contribution of the acid and alkaline conformational changes which occur. Although of lesser magnitude, the reduced form also indicates similar thermal transitions. These differences are due solely to conformational contributions to the thermal process, since the potentiometric curves are reversible. The nature of the irreversibility for oxidized cytochrome c appears to involve the loss of a group with pK′ 8.9 and the shift of two groups from pK′ 5.6 to 4.8. Thermal difference curves for this process indicate that heats of -7.8 and -24.1 kcal/mol are liberated which are centered at pH 9.3 and 3.9, respectively.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190413
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  • 2
    Electronic Resource
    Electronic Resource
    Analysis of the ionization constants and heats of ionization of reduced and oxidized horse heart cytochrome c (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2253-2261 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Simultaneous curve fitting for the ionization parameters of oxidized and reduced horse heart cytochrome c in 0.15M KCl and 20°C yields values for the ionization constants (as pK′) and the heats of ionization (ΔHi) which can reconstruct either the potentiometric or thermal titration curves. Reduced cytochrome c requires 8 sets of groups, whereas oxidized cytochrome c requires 10 sets of groups. The additional groups in the oxidized preparation appear to involve the ferriheme (pK′, 9.25; ΔHi, 13.7 kcal/mol) and a tyrosine (pK′ ≃ 10.24) that is not present in the reduced form. The potentiometric and thermal difference curves (reduced - oxidized) involve the appearance of 17 kcal/mol centered at pH 9.7 and 5.8 kcal/mol centered at pH 4.9. The carboxyl groups in both species appear to be normal for the hydrogen-bonded form. Only one histidine has normal ionization properties (pK′, 6.7; ΔHi, 7.5 kcal/mol), as do 17 of the lysine residues (pK′, 10.8; ΔHi, 11.5 kcal/mol).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360201017
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  • 3
    Electronic Resource
    Electronic Resource
    Thermolysis and Chemiluminescence of Monocyclic 1,2,4-Trioxan-5-ones (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 1851-1860 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 3,6-substituted 1,2,4-trioxan-5-ones 11-14, on heating to 170-200°, underwent unimolecular thermolysis to generate electronically excited singlet ketones with an efficiency of ca. 0.2%. The chemiluminescence quantum yields (φoSCL) depended on the nature of the 6-substitutents and increased linearly with temperature. The Arrhenius activation energies were obtained by measuring the rate of decay of luminescence and determined as 22.9, 30.4, 35.6, and 34.2 kcal/mol for 11-14, respectively. Step analysis of the chemiluminescence of 14 afforded an average activation energy of 44.3 kcal/mol. This latter result is explicable in terms of two decomposition paths, higher and lower in energy, leading to excited and ‘dark’ products, respectively. The thermolysis of trioxanones 12-14 lacking a H-atom at the 6-position is interpreted as involving successive rupture of the peroxide bond, excision of ketone at the 3-substituted end, and loss of CO2, to finally produce ketone originating from the 6-position (see Scheme 4).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19940770716
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of stoichiometry and diffusion on an epoxy/amine reaction mechanism (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 673-689 
    Details
    ISSN: 0887-624X
    Keywords: epoxy/amine mechanism ; crosslinking ; rate law ; diffusion limit ; kinetics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bulk phase kinetics of an epoxy (DGEBA) /amine (DDS) thermoset have been studied using DSC, FTIR, and 13C-NMR. In the absence of catalyst, the reaction was found to involve a main exothermic reaction between epoxide and amine hydrogen and a side reaction between tertiary amine formed in the main reaction and epoxide. The main reaction was exothermic while the side reaction had no discernable exotherm. Etherification did not occur to any significant extent. Since only the main reaction is exothermic, DSC was very useful for studying the main reaction kinetics. FTIR was used for determining whether epoxide and amine hydrogen were consumed at different rates as a way of following the side reaction. An IR band previously unused by other investigators was used to monitor the amine hydrogen concentration. NMR confirmed the above mechanism by identifying the formation of a quaternary ammonium ion/alkoxide ion pair as a reaction product of tertiary amine and epoxide. This mechanism has been successfully fit to a rate law valid over the entire extent of reaction. The rate constant for the epoxy/amine addition reaction was found to depend on hydroxide concentration (extent), reaction temperature, and glass transition temperature and included contributions from uncatalyzed and autocatalyzed parts. The side reaction (quaternary ammonium ion formation) formed weak bonds which did not affect the overall system Tg. Both reactions were second order. The rate constants for the main reaction first increase with increasing extent due to autocatalysis by hydroxide before decreasing due to the diffusion limit caused by gelation and vitrification. © 1995 John Wiley & Sons, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330409
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  • 5
    Electronic Resource
    Electronic Resource
    Stimulation by organic solvents and detergents of conversion of L-sorbose to L-sorbosone by Gluconobacter melanogenus IFO 3293For proceedings papers in this series see refs. 1 and 2. (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 17 (1975), S. 1473-1483 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Treatment of Gluconobacter melanogenus IFO 3293 cells with benzene, carbon tetrachloride, cyclohexane, deoxycholate, toluene, or xylene stimulated their conversion of L-sorbose to L-sorbosone two- to threefold. The degree of stimulation depended upon the length of exposure time to the agent and the age of the G. melanogenus cells. A rapid decrease in viability of the cells and degradation of cell RNA was noted after treatment with the effective agents. The G. melanogenus cells were unable to absorb L-sorbose actively after toluene treatment.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260171008
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  • 6
    Electronic Resource
    Electronic Resource
    Conversion of L-sorbose to L-sorbosone by immobilized cells of Gluconobacter melanogenus IFO 3293 (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 18 (1976), S. 217-237 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gluconobacter melanogenus IFO 3293 cells capable of converting L-sorbose to L-sorbosone were immobilized in polyacrylamide gel. The preferred polymer composition for high activity and stability was determined to contain a total monomer concentration of 7.2% and 16.6% crosslinking agent. No significant differences in optimal conditions for conversion, e. g., pH and temperature, were found in comparison with free cell suspensions. However, in the absence of L-sorbose, the thermal stability of immobilized cells was lower. After the initial loss, the conversion activity of immobilized cells increased, possibly due to lysis, and this increase was related to the polymerization conditions and the incubation temperature for the L-sorbose conversion.The enzymatic activity and stability of the immobilized cells also depended on the physical form of the gel and the aeration levels. Addition of electron acceptors or addition of L-sorbosone to the medium reduced, while addition of neomycin, ampicillin, chloramphenicol, and tetracycline increased the stability of the enzymatic activity.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260180208
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  • 7
    Electronic Resource
    Electronic Resource
    Enzymatic hydrolysis of lignocellulosic biomass from Onopordum nervosum (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 32 (1988), S. 341-344 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Some properties of the cellulolytic complex obtained from Trichoderma reesei QM 9414 grown on Solka floc as carbon source and its ability to hydrolyze the lignocellulosic biomass of Onopordum nervosum Boiss were studied. The optimum enzyme activity was found at temperatures between 50 and 55°C and pH ranging from 4.3 to 4.8. Hydrolysis of 4-nitropnenyl-β-D-glucopyranoside (4-NPG) and cellobiose by the β-glucosidase of the complex, showed competitive inhibition by glucose with a Ki value of 0.8 mM for 4-NPG and 2. 56 mM for cellobiose. Enzymatic hydrolysis yield of Onopordum nervosum, evaluated as glucose production after 48 h, showed a threefold increase by pretreating the lignocellulosic substrate with alkali. When the loss of glucose incurred by de pretreatment was taken into account, a 160% increase in the final cellulose to glucose conversion was found to be due to the pretreatment.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260320311
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  • 8
    Electronic Resource
    Electronic Resource
    Dissolution of a homogeneous porous medium by surface reaction (1973)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 19 (1973), S. 1190-1195 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this paper a mathematical model is used to predict the time behavior of porosity and permeability of a porous medium being dissolved by acid. Experimentally determined reaction kinetics and pore size distribution are used in the model. The acidizing process studied here is of importance in the stimulation of oil well reservoirs. A polynomial expansion method is used to obtain an approximate solution to an infinite hierarchy of moment equations resulting from application of the capillary model. Experimental porosity and permeability measurements using a sintered glass disk dissolved by hydrofluoric acid are in good agreement with predictions from the model.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690190616
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  • 9
    Electronic Resource
    Electronic Resource
    [N-Alkyl-(2-pyridyl)methanimine]copper(I) Complexes: Characterisation and Application as Catalysts for Atom-Transfer Polymerisation (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1799-1806 
    Details
    ISSN: 1434-1948
    Keywords: Atom-transfer polymerisation ; Methyl methacrylate ; Copper(I) ; Schiff base ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterisation of a series of novel bis(imine)copper(I) complexes and their use in atom-transfer polymerisation of methyl methacrylate is described. Several N-alkyl-(2-pyridyl)methanimines (alkyl = n-butyl, isobutyl, sec-butyl, n-propyl) and N-(n-propyl)-1-(2-pyridyl)ethanimine as ligands have been fully characterised. Three bis[N-alkyl-(2-pyridyl)methanimine]copper(I) complexes, [Cu{(C5H4N)CH=N(iBu)}2][BF4], [Cu{(C5H4N)C(CH3)=N(nPr)}2][PF6], and [Cu{(C5H4N)CH=N(sBu)}2][BF4] have been structurally characterised; all having a distorted tetrahedral arrangement of co-ordinating nitrogen atoms surrounding the metal centre. All of the catalysts were found to be effective atom-transfer polymerisation catalysts for the polymerisation of MMA in hydrocarbon solution. However, it was discovered that the performance of the catalysts containing n-alkyl substituents was superior to those containing branched alkyl substituents. The presence of branching in the alkyl substituent results in a reduction of reaction rate and a corresponding broadening of the polydispersity index.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Electrostatic effect of the polar bond-polarizable bond interaction on 13C chemical shifts (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 70 (1998), S. 105-112 
    Details
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the present work, a theoretical analysis was carried out on the effect of the proximity of a polar bond to a polarizable bond on the magnetic shielding constants of the nuclei belonging to the polarizable bond. In particular, the case of 13C magnetic shielding constants in a vinylic C=C bond is considered. The electric field of the polar bond is simulated by two opposite point charges proximate to the C=C bond in (I) C2H4 and (II) (OH)HC2H2. Changes in the 13C magnetic shieldings as well as the polarization of the π C=C bond are evaluated as a function of the magnitudes of such point charges. The shielding effect on the C nucleus proximate to the positive charge is of the same order of magnitude as that experimentally determined in aryl methyl ethers. The present analysis yields theoretical support to the assumption that changes in magnetic shielding constants can be adequate probes to detect the stabilization effect in a molecular system originating in an electrostatic interaction between a polar bond proximate to a polarizable bond.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 105-112, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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