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131.
A systematic series of ESCA measurements in Pt1?xCux manifest observable shifts for only the Cu core levels. These shifts are linearly related to the corresponding centroids of the valence band spectra. Physical arguments permit extraction of electronic valence structure changes induced by alloying from the measured quantities. Changes in Fermi energy are not related to differences in work function. The Pt valence structure appears unchanged and the Cu structure exhibits dehybridization. There is little charge transfer. 相似文献
132.
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135.
Raghvendra S. Yadav Avinash C. Pandey Sharda Sundaram Sanjay 《Structural chemistry》2007,18(6):1001-1004
ZnO porous structures have been fabricated by cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal process. X-ray diffraction
(XRD) pattern indicated that the synthesized ZnO porous structures were hexagonal. It is found that CTAB influences the morphology
of ZnO structures. On the basis of structural information provided by XRD, SEM, and TEM, a growth mechanism is proposed for
the formation of ZnO porous structures. 相似文献
136.
P. V. Sundaram 《Applied biochemistry and biotechnology》1978,3(3):241-246
The determination of kinetic parameters such as the apparent Michaelis constant (Km app.) of enzymic reactions occurring at a mixed interface, that is, at a solid/liquid interface where the catalyst is bound to the solid phase, can lead to values that are too high when an unstirred layer is present. The perturbatior, for which an equation is derived in this paper, depends on the thickness of the unstirred layer, the maximal catalytic rate, and the diffusion constant. An additional error is introduced by the graphical determination of Km using the Lineweaver-Burk plot since after transformation the relation is not linear if an unstirred layer is present. A numerical example shows that apparent Michaelis constants obtained from in vitro experiments involving immobilized enzymes can lead to misleading results originating from conditions used in experiments such as stirring rate (CSTR-continuous stirred tank reactors) or flow rate (packed-bed reactors) of substrate. This can partly be explained by a greater bias of the Km determination caused by unstirred layers of the liquid medium (substrate) being present around the solid particles onto which the enzyme molecules are attached. 相似文献
137.
The nature of the substituent is found to exhibit a profound influence on the mechanism of oxidation of anilides by iodate. The process appears to be smooth with electron-releasing groups, while it involves consecutive reactions with electron-withdrawing groups. Azobenzenes and quinones are obtained as the major products with electron-releasing and withdrawing groups, respectively.
. - , - . -, .相似文献
138.
The kinetics of cerium(III) ion catalyzed Br(V) oxidation of oxalic acid in the presence of HClO4/H2SO4 and mercury(II)-a bromide removing ion, exhibits second order each in [br(V)] and [acid], 0.4 and zero order in [Ce(III)]. However, the kinetic behavior of oxalic acid is anomalous with –0.7, zero and 1.4 order. The chemistry underlying the phenomena is discussed.
Br(V), Ce(III), HClO4/H2SO4 (II), , [Br(V)], [], 0,4 [Ce(III)]. , , .. –0,7, 0 1,4. , .相似文献
139.
140.
P. V. Sundaram 《Applied biochemistry and biotechnology》1978,3(3):185-197
A coupled enzyme nylon tube reactor has been made by simultaneously immobilizing rabbit muscle pyruvate kinase (EC 2.7.1.40) and lactate dehydrogenase (EC 1.1.1.27) onto the inside surface of a nylon tube initially derivatized with poly (scl)-lysine to serve as a spacer molecule. The enzymes were covalently linked to the amino groups of the poly lysine spacer molecule by cross-linking with glutaraldehyde. The coupled enzyme system may be used in routine analysis to determine the concentrations of PEP, ADP, pyruvate, and NADH in a given solution and also to modify radioactively labeled nucleotides. The kinetic properties of the enzymes appear to be partially diffusion controlled as shown by an inverse relationship ofK m(app) values and activities to the flow rate of substrates through the tube reactor. This coupled enzyme system may be used as an indicator system when used in conjunction with other enzymes to complete a sequence of catalytic steps. An example of this is demonstrated in this paper by linking a nylon tube supported acetate kinase (EC 2.7.2.1) to this coupled enzyme system so that the three enzymes function in a series that facilitates the estimation of acetate. 相似文献