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81.
82.
Saburo Yamaguchi Hisao Hayashi Fumiyuki Hamada Akio Nakajima 《Journal of Polymer Science.Polymer Physics》1984,22(9):1551-1559
Scattering functions for amylose chains have been calculated as a statistical mechanical average over eligible configurations based on the rotational isomeric state approximation. Main emphasis has been placed on an intermediate-angle range (0.1 < h = (4π/γ)sinθ < 1.0 Å?1) where the scattering function is sensitive to local chain configurations. In order to avoid overestimation of the regularity of chain configurations, the rotational isomeric states for each glycosidic bond have been defined by a set of discrete torsion angles at intervals of 5°. Pair correlation functions for atoms separated by sequences shorter than 31 glucose units are evaluated by the Monte Carlo method, while the interference for longer sequences is calculated by a series expansion in the even moments of the chain. All carbons and all skeletal oxygens are treated as point scatterers in order to incorporate all the interferences between atoms in unit pairs in the calculations. The calculated scattering function shows appreciable oscillation at intermediate angles, reflecting the characteristic helical tendency of the configurations. The Debye function is found to be inadequate in the intermediate-angle region owing to the non-Gaussian character of the distribution function and to breakdown of the assumption that the mean-square distance between a pair of atoms is proportional to the number of bonds between them, because of the bulkiness of the glucose unit. 相似文献
83.
Summary The thermodynamic interaction parameters for linear polyethylene-n-alkanes were investigated with n-C6H14, n-C7H16, n-C8H18, n-C18H38, and n-C32H66 as diluents, by determining the melting temperatures of polyethylene in its mixtures with n-alkanes. It follows that, with increasing the number of carbon atom in n-alkanes, the entropy parameter
1 increases, the enthalpy parameter
1 remains approximately equal to zero, and the free energy parameter
1 decreases and approaches to zero. The change of the interaction parameters with the number of carbon atom in n-alkanes were discussed byPrigogine's theory.
Zusammenfassung Die thermodynamischen Wechselwirkungsparameter für das System lineares PolyÄthylen/n-Alkane wurden durch die Schmelzpunktsmessungen von PolyÄthylen in den Mischungen mit n-Alkanen bestimmt. Die als Verdünnungsmittel verwandten n-Alkane waren n-C6H14, n-C7H16, n-C8H18, n-C18H38 und n-C32H66. Es wurde gefunden, da\ mit steigender Zahl der Kohlenstoffatome in den n-Alkanen der Entropieparameter 1 zunimmt, wÄhrend der Enthalpieparameter 1 annÄhernd Null bleibt. Der Parameter der freien Energie 1 nimmt ab und nÄhert sich Null. Die VerÄnderung der Wechselwirkungsparameter von der Zahl des Kohlenstoffatome in den n-Alkanen wurden nach der Prigogineschen Theorie diskutiert.相似文献
84.
Ozawa F Okamoto H Kawagishi S Yamamoto S Minami T Yoshifuji M 《Journal of the American Chemical Society》2002,124(37):10968-10969
The (pi-allyl)palladium complex bearing an sp2-hybridized phosphorus ligand (DPCB-OMe: 1,2-bis(4-methoxyphenyl)-3,4-bis[(2,4,6-tri-tert-butylphenyl)phosphinidene]cyclobutene) efficiently catalyzes direct conversion of allylic alcohols in the absence of activating agents of alcohols such as Lewis acids. N-Allylation of aniline proceeds at room temperature to afford monoallylated anilines in 90-97% yields. C-Allylation of active methylene compounds is also successful at 50 degrees C using a catalytic amount of pyridine as a base, giving monoallylation products in 85-95% yields. The catalytic mechanism involving hydrido- and (pi-allyl)palladium intermediates has been proposed on the basis of stoichiometric examinations using model compounds of presumed intermediates. 相似文献
85.
Supersaturation ratio, S, has been theoretically related to the supply rate of solute, Q, from growth rate and mass-balance equations in the quasi-steady state in the growth process of isotropic monodisperse particles. The derived equation, (S - 1) = (1/D + 1/kr)(Q/betaC(0)nr) + 2V(m)gamma/rRT, suggests a linear dependence of S on Q under constant n and r, where D is the diffusion coefficient, k is the rate constant for surface-reaction, C(0) is the solubility, n and r are the number and radius of growing particles, respectively, V(m) is the molar volume of particles, R is the gas constant, T is the absolute temperature, and beta is the shape factor defined by beta identical with (1/r(2)) dupsilon/dr, where upsilon is the volume of an individual particle. The equation was applied to the analysis of growth kinetics and determinations of critical supersaturation ratio in monodisperse AgBr particles in the controlled double-jet system with the assistance of a potentiometric supersaturation measurement. In both cubic and octahedral particles, growth rates were completely limited by diffusion and surface-reaction at pBr ( identical with -log[Br(-)]) 3.0 and 1.0, respectively, while the growths were intermediate of them at pBr 2.0 and 4.0. The growth parameters, DC(0) and kC(0), were experimentally determined. Also, critical supersaturation ratio was estimated as 1.28 as an average in the present study. 相似文献
86.
Nahoko Uchiyama Fumiyuki Kiuchi Yoshio Takeda Ozodbek A. Ashurmetov 《Tetrahedron letters》2004,45(3):531-533
A new diterpene, komarovispirone (1) with a spiro-octahydroindene skeleton, was isolated from Dracocephalum komarovi. The structure was elucidated by extensive analyses of spectral data. Komarovispirone (1) showed trypanocidal activity against epimastigote of Trypanosoma cruzi, the causative agent of American trypanosomiasis, with a minimum lethal concentration of 23 μM. 相似文献
87.
Akio Nakajima Hiroshi Fujiwara Fumiyuki Hamada 《Journal of Polymer Science.Polymer Physics》1966,4(3):507-518
Phase equilibria between linear polyethylene and a number of organic diluents of varying type have been investigated. The diluents include aliphatic alcohols, alkyl phenols, aryl phenols, diphenyl derivatives, alkyl aryl ethers, esters, and ketones. It is found that n-octyl alcohol, n-decyl alcohol, n-lauryl alcohol, p-tert-amyl alcohol, p-octyl phenol, p-nonyl, phenol, diphenyl, diphenylmethane, diphenyl ether, benzyl phenyl ether, and anisole are Θ-solvents for linear polyethylene at temperatures between 120 and 200°C. Thermodynamic interactions are discussed in relation to the type of diluent. 相似文献
88.
Rader S. Jensen Anil S. Gajare Masaaki Yoshifuji Fumiyuki Ozawa 《Tetrahedron letters》2005,46(50):8645-8647
A palladium complex bearing 1,2-diphenyl-3,4-diphosphinidenecyclobutene ligand (DPCB) has been used to facilitate the catalytic cyanation of aryl bromides. A series of substituted benzonitriles was prepared in good to high yields by the treatment of the corresponding aryl bromides with Zn(CN)2 in N-methyl-2-pyrrolidone in the presence of 2-4 mol % catalyst at 100 °C for 16 h. 相似文献
89.
90.
Trypanocidal constituents of the fruits of Vitex trifolia were investigated. Activity-guided isolation of the acetone extract resulted in the isolation of two new norditerpene aldehydes, 1 and 2, together with five known diterpenes: vitexifolin E (3), vitexifolin F (4), vitexilactone (5), 6-acetoxy-9-hydroxy-13(14)-labden-16,15-olide (6), and previtexilactone (7). In vitro minimum lethal concentrations of the isolated compounds against epimastigotes of Trypanosoma cruzi were 11 microM (1), 36 microM (2), 34 microM (3), 34 microM (4), 66 microM (5), 66 microM (6), and >265 microM (7). 相似文献