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981.
8‐Hydroxy‐1,3,6‐pyrene trisulfonic acid, trisodium salt (pyranine), readily reacts with peroxyl radicals generated in the aerobic pyrolysis of 2,2′‐azobis(2‐amidinopropane) (AAPH). The process can be followed by monitoring the decrease in pyranine absorbance (460 nm) or fluorescence (excitation: 460 nm; emission: 510 nm). The reaction follows a nearly zero‐order kinetics in pyranine (0.25–30 μM range), suggesting a very efficient trapping of peroxyl radicals. In agreement with this, the process is order one in AAPH. The bleaching process is totally prevented by Trolox (μM range), and partially prevented by Trp (mM range). The protection afforded by Trp is very little dependent upon the pyranine concentration. This result indicates that the main protective pathway is not a competitive scavenging of the peroxyl radicals. The data suggest protection due to repair of the initially produced pyranyl radicals. These radicals are also very efficient in the destruction of C‐phycocyanin bilin groups. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 525–531, 2003 相似文献
982.
Heriberto Espinoza-Gómez Shui Wai Lin Eduardo Rogel-Hernández 《Heat and Mass Transfer》2005,41(6):503-509
This paper present a method to determine pore diameters and effective transport through membranes using a mixture of oligosaccharides. The results are compared with the Maxwell–Stefan equations. The partition coefficients of the solutes are a function of the pore diameter according to the Ferry equation. Thus, with the pore diameter as the only unknown parameter, rejection is described and the pore diameter is obtained by a Marquardt–Levenberg optimization procedure. 相似文献
983.
Eduardo Gallego 《Differential Geometry and its Applications》2005,22(3):315-325
Using results from integral geometry, we find inequalities involving mean curvature integrals of convex hypersurfaces in hyperbolic space. Such inequalities generalize the Minkowski formulas for euclidean convex sets. 相似文献
984.
Francisco Garcia Sanchez Miguel Hernandez Lopez Eduardo de Gracia Villodres 《Mikrochimica acta》1987,92(4-6):217-224
1,2-Diaminoanthraquinone forms a 11 inclusion complex with-cyclodextrin in aqueous media and at different pH. This can be employed to solubilize the anthraquinone in water for use as a ligand for metal ions. This ligand can be used to determine palladium at trace levels spectrophotometrically. The limit of detection is 11 ng/ml and the R.S.D. is 2.1%. The performance can be improved by using derivative spectrometry. 相似文献
985.
A general method for evaluation of equilibrium geometries and vibronic transition intensities of crystalline excimers is described. The method provides realistic potential surfaces which include, in addition to the α electron surfaces, also the repulsive hard core of the α electrons and the effect of the crystal potential. The method is applied to the study of the potential surfaces of the pyrene excimer, both in the crystal and in the gas phase. The method is also used for a direct evaluation of the vibronic structure of the excimer emission. The calculations reproduce the main experimentally observed properties including the structureless envelope of the emission band and the temperature dependence of its line width. 相似文献
986.
In the hydroformylation of racemic 3-phenyl-1-butene in the presence of an asymmetric rhodium-catalyst different regioselectivities have been observed for the two enantiomers, as indicated by the optical activity of the products. 相似文献
987.
The conditions that ensure that an optimal variational wave function ø under general restricting requirements satisfies the hypervirial theorem are analysed. Application is made to a system where thez -component of angular momentum is a constant of motion and results are discussed in connection with those obtained via symmetry considerations. 相似文献
988.
989.
Felix Splinder György Bor Urs K. Dietler Piero Pino 《Journal of organometallic chemistry》1981,213(1):303-312
The formation of a new compound, the most characteristic IR absorption bands of which appear at 2007 cm-1 and 1956 cm-1, has been in the reaction between Co2(CO)8 and Rh4(CO)12 under carbon monoxide pressure in a hydrocarbon medium. The same compound is also formed either by the reaction of Co2(CO)8 with [Rh(CO)2Cl]2 or by the reaction of Co3Rh(CO)12 with carbon monoxide. The new complex has not been isolated in a pure state, but the formula CoRh(CO)7 is proposed on the basis of the stoichiometry of its formation and its physico-chemical properties. Equilibrium constants and thermo-dynamic parameters for the reaction 2 Co2(CO)8 + Rh4(CO)12 4 CoRh(CO)7 have been estimated. Possible structures for the new complex are discussed on the basis of its IR spectrum. 相似文献
990.
Let n be a positive integer. For each \({0 \leq j \leq n-1}\), we let \({C_{n}^{j}}\) denote Cayley graph for the cyclic group \({\mathbb{Z}_n}\) with respect to the subset \({\{1, j\}}\). For any such pair (n, j), we compute the size of the Grothendieck group of the Leavitt path algebra \({L_K(C_{n}^{j})}\); the analysis is related to a collection of integer sequences described by Haselgrove in the 1940s. When j = 0, 1, or 2, we are able to extract enough additional information about the structure of these Grothendieck groups so that we may apply a Kirchberg-Phillips-type result to explicitly realize the algebras \({L_K(C_{n}^{j})}\) as the Leavitt path algebras of graphs having at most three vertices. The analysis in the j = 2 case leads us to some perhaps surprising and apparently nontrivial connections to the classical Fibonacci sequence. 相似文献