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  • 11
    Electronic Resource
    Electronic Resource
    Polymerization of acrylamide in aqueous medium initiated with a redox system composed of cysteine and potassium bromate (1997)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 198 (1997), S. 2027-2034 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Aqueous polymerization of acrylamide initiated with a redox initiator system composed by cysteine and potassium bromate was investigated as a model of the redox initiator system composed of poly(vinyl alcohol) having a thiol groups at one end and potassium bromate. The rate of polymerization was proportional to almost the square root of cysteine and potassium bromate concentration, indicating the initiation system is a usual free radical polymerization initiator. On the other hand, the rate was proportional to the 1.8th power of the monomer concentration. The activation energy of the rate of polymerization was about 5 kcal · mol-1, indicating also a typical redox initiation system. Chain transfer constant of polyacrylamide radical to cysteine was calculated to be 0.4. From these results, it is concluded that cysteine exerts two important roles: (1) as a reductant of the redox initiation and (2) as a powerful chain transfer reagent.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1997.021980703
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  • 12
    Electronic Resource
    Electronic Resource
    AB INITIO MO AND MONTE CARLO SIMULATION STUDY ON THE CONFORMATION OF L-ALANINE ZWITTERION IN AQUEOUS SOLUTION (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 145-151 
    Details
    ISSN: 0894-3230
    Keywords: ab initio calculation ; Monte Carlo simulation ; solvent effect ; alanine ; conformation ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conformation of the L-alanine zwitterion (ALAZ) in aqueous solution was examined by an ab initio MO method including the solvent effect with the generalized Born (GB) equation. The geometry optimization with the 6-31++G* basis set gave the (φ, θ)=(80, 8) conformation as the most stable conformation of ALAZ in aqueous solution, where φ is the HNCαC torsional angle and θ is the NCαCO torsional angle. Stabilization by the solvent is larger in the θ=90° conformation than in the θ=0° conformation. However, the differential solvation is small and the conformation with a nearly planar NCαCO skeleton is the most stable conformation in aqueous solution. The barrier to rotation of the CO2 group (θ rotation) was calculated to be 6·7 (6-31++G*) and 5·9 (MP2/6-31++G*) kcal mol-1, while that to rotation of the NH3 group (φ rotation) was very small (〈1 kcal mol-1). The relative free energy of solvation and relative stability among the representative conformations of ALAZ were calculated by Monte Carlo (MC) simulation with the statistical perturbation method. The energy variation along the θ rotation indicated that the value of θ=5-10° is favorable for ALAZ in aqueous solution. The MC simulation supports the ab initio GB results for the conformational properties of ALAZ in aqueous solution. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    Ab initio GB study of chemical intermediates in solution; Ethylenesulfonium ion in hydrolysis of 2-chloroethyl methyl sulfide (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 9 (1998), S. 503-510 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio MO theory including solvent effects has been applied to the structure and reactivity of methyl ethylenesulfonium ion, 1, in aqueous solution as a model of the three-membered cyclic sulfonium intermediate expected in the toxic action of sulfur mustard. The 6-31 + G* geometry optimization of the cyclic sulfonium ion 1 suggested that the ring size of 1 is expanded slightly by solvation. The contour lines map of the interaction energy between 1 and Cl- has a very shallow and wide well at 5-6 Å distance from 1. This is the solvent-separated ion pair, and the contact ion pair was not found between 1 and Cl-. The calculated energy diagrams for the SN2-type reactions of 1 with Cl-, H2O, and OH- that give ring-opened compounds indicated the following: (1) The energy of the 1 + Cl- system is similar to that of chloroethyl methyl sulfide (CEMS, 2), and the interconversion between 1 + Cl- and 2 occurs easily in aqueous solution. The 3-21 + G(*) and 6-31 + G* activation energies for the 2 → 1 + Cl- reaction, 20-22 kcal/mol, agree well with the experimental enthalpy of activation for the hydrolysis of 2. (2) The reaction of 1 with OH- gives a very stable hydroxyl compound, 4, and no transition state was found. (3) The reaction of 1 with H2O gives an unstable addition product that is expected to be converted to 4 with the assistance of another H2O molecule. This mechanism is consistent with that proposed by Bartlett and Swain in their pioneering work on the hydrolysis of sulfur mustard. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:503-510, 1998
    Additional Material: 6 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    Ab initio MO study of the solvent effect on the SN2 reaction of the trimethylsulfonium cation with chloride anion (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 7 (1996), S. 273-279 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A recently developed ab initio MO theory including solvent effects has been applied to a typical cation-anion reaction, the SN2 reaction of the trimethylsulfonium cation with the chloride anion. In the gas phase, the trimethylsulfonium and chloride ions are unstabilized, and the reaction is expected to proceed rapidly. In aqueous solution, the reactant ions are largely stabilized, and the reaction has been predicted to be endothermic, with an activation energy of 30-40 kcal/mol. This potential energy profile, which agrees with experimental results, has been well elucidated by differential solvation at several stages of the reaction path. At the transition state of this reaction, the C and H atoms in the transferring CH3 group are almost in a plane that is perpendicular to the Cl(SINGLE BOND)C(SINGLE BOND)S line, reflecting the concerted nature of the reaction. The population analysis has shown that the electrons in the C(SINGLE BOND)S bond are mostly withdrawn by the sulfur atom at the transition state and that the electron transfer from Cl to CH3 occurs after the transition state. The calculated activation energy for the reaction in ethanol is smaller than that in water. This agrees with experiments. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Novel thermally reversible hydrogel as detachable cell culture substrate (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 40 (1998), S. 631-639 
    Details
    ISSN: 0021-9304
    Keywords: thermoresponsive polymer surface ; interpenetrating network ; cell culture ; cell detachment ; epithelial cell ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A novel UV crosslinkable co-polymer of 4-(N-cinnamoylcarbamide)methylstyrene (CCMS) and N-isopropylacrylamide (IPAAm) was partially entrapped in traditional tissue-culture-treated polystyrene and crosslinked by UV light irradiation. Dishes modified by this method showed a change in contact angle with respect to temperature as compared to tissue culture polystyrene controls. Surface chemical analysis indicated that the crosslinked hydrogel does not detach from the surface after successive rinsing in ethanol and water, keeping the cells or cell construct free of unwanted soluble polymer after detachment. Cultures of both bovine endothelium and human retinal pigmented epithelium were confirmed to be able to attach and grow on the polymer-modified surfaces morphologically identical to that on control tissue culture polystyrene surfaces. Corresponding to a change in temperature, these cultures would detach and could be transplanted to another culture surface without functional and structural changes. These results show that the new, photo-crosslinkable hydrogel system can utilize the hydrophobic/hydrophilic change of the surface for cell culture detachment while being permanently applicable to any tissue culture geometry. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 631-639, 1998.
    Additional Material: 5 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    NUMERICAL SIMULATION OF THE PHENOMENA DUE TO THE PASSING-BY OF TWO BODIES USING THE UNSTEADY BOUNDARY ELEMENT METHOD (1996)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 23 (1996), S. 445-454 
    Details
    ISSN: 0271-2091
    Keywords: boundary element method ; unsteady aerodynamic force ; relative motion ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this paper a numerical analysis was made to investigate the aerodynamic forces surrounding two bodies in relative motion in a fluid at rest in three dimensions. The unsteady boundary element method was employed in the numerical calculations. This method is very convenient for obtaining an approximate expression of the velocity potential, especially for practical use. The passing-by of two spheres in an incompressible perfect fluid which extends to infinity is treated by the present method. The resultant pressure coefficients on two spheres passing each other in opposite directions are calculated and discussed numerically. Numerical examples are presented to show the validity of the present method. The method is also applied to the calculation of the passing-by of two trains in an open area in order to investigate its applicability.
    Additional Material: 10 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Relationship between heat of combustion, lignin content and burning weight loss (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 22 (1998), S. 1-6 
    Details
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The measurements of effective heat of combustion obtained from the Cone Calorimeter test for several wood composites (different types of plywood and particle board) at horizontal configuration are presented. Comparison of the average effective heat of combustion at different irradiation shows no correlation to gross heat of combustion measured in the oxygen bomb calorimeter. It was also found, that for the materials studied, there is no statistically significant correlation of heat of combustion to lignin content, but on the other hand, there is an evidence of correlation to the burning weight loss of the samples, but further investigation is necessary. Additionally, the effective heat of combustion is shown as a function of time for different external radiant heat-flux level for the chosen materials. Similar profiles have been found for remaining samples. Two different types of such curves can be distinguished. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 7 Ill.
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  • 18
    Electronic Resource
    Electronic Resource
    Topology optimization of compliant mechanisms using the homogenization method (1998)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 42 (1998), S. 535-559 
    Details
    ISSN: 0029-5981
    Keywords: optimal design ; topology optimization ; compliant mechanisms ; homogenization method ; mutual energy ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A procedure to obtain a topology of an optimal structure considering flexibility is presented. The methodology is based on a mutual energy concept for formulation of flexibility and the homogenization method. A multi-objective optimization problem is formulated as an application of compliant mechanism design. Some examples of the design of compliant mechanisms for plane structures are presented. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 18 Ill.
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  • 19
    Electronic Resource
    Electronic Resource
    Elektrochemische und ab-initio-Untersuchung des Dimetallofullerens La2@C80Diese Arbeit wurden vom japanischen Ministerium für Erziehung. Wissenschaft und Kultur (Nr. 06224230) gefördert. (1995)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 107 (1995), S. 1228-1230 
    Details
    ISSN: 0044-8249
    Keywords: Ab-initio-Rechnungen ; Elektrochemie ; Lanthanverbindungen ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19951071025
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  • 20
    Electronic Resource
    Electronic Resource
    Synthese der ersten Addukte der Dimetallofullerene La2@C80 und Sc2@C84 durch Addition eines DisiliransDiese Arbeit wurde von der Iketani Science and Technology Foundation sowie durch einen Grant-in-Aid for Scientific Research on Priority Area (Nr. 06224204) des japanischen Ministeriums für Erziehung, Wissenschaft und Kultur gefördert. (1995)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 107 (1995), S. 2303-2304 
    Details
    ISSN: 0044-8249
    Keywords: Fullerene ; Lanthanverbindungen ; Scandiumverbindungen ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19951071915
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