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Gabriela Ionita Petre Ionita Victor EM. Sahini Constantin Luca 《Journal of inclusion phenomena and macrocyclic chemistry》2001,39(3-4):269-271
The kinetics of oxidation of amino acids (Arg, His, Lys, Phe, Thr and Tyr), a dipeptide (Gly-His), and BSA (bovine serum albumin) by two persistent water soluble free radicals of the hydrazyl type has been studied.The rate decreases in the order Arg>Lys>Tyr>Thr>HisBSAPheGly-His with bothfree radicals. Addition to the reaction mixture of - and -cyclodextrin decreases the oxidation rate, probably due to amino acidencapsulation in the cyclodextrin cavity. -Cyclodextrin protects more efficiently against oxidation than -cyclodextrin. 相似文献
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Superconducting YBa2Cu2.955Fe0.045O7 has been studied at temperatures between 300 and 1000 K. Spectra were recorded on a sample which was sealed as a pellet pressed with boron nitride. An atmosphere of oxygen was maintained in the sample region at all times. At temperatures up to 900 K, we observed the four iron sites A, (Cu(1) chain-site; square planar oxygen coordination with O(5) vacancy on thea-axis), B, (Cu(2) plane-site; square pyramidal oxygen coordination), C, (Cu(1) chain-site; square pyramidal oxygen coordination with O(5) site occupied) and D, (Cu(1) chain-site; quasi-tetrahedral oxygen coordination with O(4) vacancy along theb-axis). At temperatures up to 700 K, the relative area of the B and C sites remained nearly constant as the temperature was increased. However, the area of the A site decreased while, the D site area increased with increasing temperature. At all times, the total area of sites A and D remained constant, thereby indicating the possibility of oxygen atom hopping in thea-b plane. The quadrupole splitting of each site, except the B site, decreased linearly with increasing temperature.Research supported in part by the Old Dominion University Undergraduate Research Program. 相似文献
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D. W. Greeno M. S. Sommers R. N. Wolff 《The Journal of the Operational Research Society》1977,28(4):829-838
A number of transportation demand models have been formulated using the abstract mode concept. Unfortunately, most of these models use a priori economic theory to derive the variables used in the analysis. This study describes an empirical approach for the specification of mode attributes used by purchasers of transportation modes for the movement of commodities. Results reported from a study conducted on the Montreal-Toronto corridor in Canada suggest that a number of important variables have been neglected in models of carrier selection for freight. 相似文献
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Random contractions (subunitary random matrices) appear naturally when considering quantized chaotic maps within a general theory of open linear stationary systems with discrete time. We analyze statistical properties of complex eigenvalues of generic N × N random matrices  of such a type, corresponding to systems with broken time reversal invariance. Deviations from unitarity are characterized by rank M≤N and a set of eigenvalues 0<T i≤1, i=1,..., M of the matrix $\hat T = \hat 1 - \hat A^\dag \hat A$ . We solve the problem completely by deriving the joint probability density of N complex eigenvalues and calculating all n-point correlation functions. In the limit N?M, n, the correlation functions acquire the universal form found earlier for weakly non-Hermitian random matrices. 相似文献
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Westrum E. F. Justice B. H. Sommers J. A. Johnson D. A. 《Journal of Thermal Analysis and Calorimetry》1999,57(3):659-667
This paper is concerned with the estimation of heat capacities in the IVA 3d-transition element compounds using especially Zr and Hf compounds as examples. Most prediction schemes routinely tacitly assume that volumes and masses trend in parallel. However, the lanthanide contraction here ensures for ZrX/HfX systems — and generally elsewhere — that this is not so in this portion of the periodic table. Available methods such as Latimer's, Volumetric Priority, Komada-Westrum, Grimvall's, and Sommers' are compared on IVA elements and compounds. Only the Sommers approach has volumetric input. It provides the best prediction.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
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The density of states for the Ni-Cu alloy system has been calculated as a function of concentration by the supercell method. This method takes into account inter-site interactions in contrast with current effective medium or single site theories. We show that the method is practical for the study of disordered systems. Comparison is made with previous work as well as with photoemission data. 相似文献
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