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171.
The research described in this paper presents a method for chemically modifying the surface of plant photosynthetic membranes
in such a way that electrical contact can be made. Colloidal platinum was prepared, precipitated directly onto thylakoid membranes
from aqueous solution, and entrapped on fiberglass filter paper. This composition of matter was capable of sustained simultaneous
photoevolution of hydrogen and oxygen when irradiated at any wavelength (400–700 nm) in the chlorophyll absorption spectrum.
Experimental data support the interpretation that part of the platinum metal catalyst is precipitated adjacent to the photosystem-I
reduction site of photosynthesis and that electron transfer occurs across the interface between photosystem I and the catalyst.
When contacted with metal electrodes, the thylakoid-platinum combination was capable of generating a sustained flow of current
through an external load resistor. Procedures for preparing this material and experimental data on its catalytic and electronic
properties are presented. Also presented is an analysis of the flow of photocurrent in terms of the interfacial electron transfer
reactions that occur at the interfaces of the components of the assembly. 相似文献
172.
A. Bismarck M. Pfaffernoschke M. Selimović J. Springer 《Colloid and polymer science》1998,276(12):1110-1116
The grafting method that has successfully been applied to methacrylic acid and liquid crystalline monomers was expanded to
prepare amphoteric carbon fiber surfaces using 2-(N,N-dimethylamino)ethyl methacrylate as monomer. The obtained carbon fiber surfaces were characterized by contact angle and ζ-potential
measurements. The expected basic behavior was not observed, instead an amphoteric character of the modified carbon fiber surface
was found. The fiber surfaces display a basic character in the acidic pH-range, while they are acidic in the alkaline part
of the pH-scale.
An important influence is derived from the amount of initiator used to graft the monomers onto the fibers. The smaller the
initiator concen-tration used during polymerization, the larger the amount of amino functionalities introduced to the carbon
fiber surface.
The wetting behavior versus water depends on the overall conformation of the immobilized polymer. During immersion into water
the polymer acts hydrophobic, while during emersion, a hydrophilic character is observed, probably derived from conformational
changes and swelling during the contact angle measure-ments in water.
Received: 9 June 1998 Accepted: 13 August 1998 相似文献
173.
A series of acrylic ester copolymers with viologen group as pendant were synthesizedthrough the reaction of MMA-EBA (Ethenyl bromoacetate) copolymer with 4-(4'-pyridyl)-N-alkyl (or arylalkyl) pyridiniums. These viologen copolymers can exchange their anionwith NH_4PF_6 in methanol to improve their solubility in organic solvents such as DMFand acetone. Compared with the corresponding low molecular viologens, these viologencopolymers have relatively lower color development rate under UV light and fade fasterin air due to less affinity to photo-reductant and deficiency of association between theircation radicals. Their photofatigue resistant ability is also slightly better than that of lowmolecular vinlogens. 相似文献
174.
The title reaction has been used as an example to test the importance of using a hindered rotor treatment instead of a harmonic oscillator model for calculating vibrational partition functions corresponding to low-frequency internal rotation modes. First, a normal-mode analysis according to the Ayala and Schlegel's algorithm has been used to identify the internal rotation modes of methanethiol and the transition state structure. Then, after calculation of the energy barrier for each internal rotation, the corresponding hindered rotor partition functions have been calculated following the CW scheme of Chuang and Truhlar. The results show that the anharmonic treatment produces a rather modest improvement of the rate constants at room temperature or below. 相似文献
175.
Kinetics of chemiluminescence reactions of 2-methyl-6-phenylimidazo[1,2-a]pyrazin-3(7H)-one (1c, Cypridina luciferin analogue) and substituent effects of the 6-aryl group of derivatives 1 strongly suggest that the rate-determining step is a single electron transfer from an anion derived from 1 to a triplet molecular oxygen (O2) in the oxygenation process. 相似文献
176.
Summary {\rtf1\ansi\ansicpg1250\deff0\deflang1038\deflangfe1038\deftab708{\fonttbl{\f0\froman\fprq2\fcharset238{\*\fname Times New Roman;}Times New Roman CE;}}
\viewkind4\uc1\pard\f0\fs20 New explanations are given for two types of irregular thermogravimetric (TG) data. A TG relationship between mass and temperature is derived on the basis of migration behavior of bubbles generated in bulk of sample system, and superposed on that derived on the basis of kinetics of the 4\super th\nosupersub order event, which is superposed on the experimental TG data obtained from three reference papers. This suggests that these TG data are reflecting migration of bubbles. A dependence of TG behavior on heating rate, which is contrary to usual that, is shown and is explained in terms of event-rate determination by boiling.
\par } 相似文献
177.
The thermal decomposition characteristics of1,7-diazido-2,4,6-trinitrazaheptane (DATH) and multi-component systems containing
DATH were studied by using DSC, TG and DTG techniques. Three –NO2 groups in the DATH molecule break away first from the main chain when DATH is heated up to 200°C. Following this process,
the azido groups and the residual molecule decompose rapidly to release a great deal of heat within a short time. In the multi-component
systems, DATH undergoes a strong interaction with the binder of the double-base propellant and a weak interaction with RDX.
The burning rates of the two propellants were determined by using a Crawford bomb. The results showed that the burning rate
rises by about 19–66% when 23.5%DATH is substituted for RDX in a minimum smoke propellant. Meanwhile, the N2 level in the combustion gases is enhanced, which is valuable for a reduction of the signal level of the solid propellant.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
178.
O. F. Shlensky 《Journal of Thermal Analysis and Calorimetry》1993,40(3):941-947
New modifications of a contact heater are suggested for investigating thermal decomposition processes, as well as for determining
kinetic characteristics of substances under conditions of intense heating to a fixed constant temperature.
Zusammenfassung Zur Untersuchung von thermischen Zersetzungsprozessen und der Bestimmung der Reaktionskinetik von Substanzen bei intensivem Erhitzen auf vorgegebene konstante Temperaturen wird eine neue Abart von Kontakterhitzern beschrieben.相似文献
179.
E. P. Honig 《Rheologica Acta》1987,26(1):2-6
Equations are derived for the coaxial cylinder system in the combined oscillatory and steady-state shear mode. The limitations of the use of the various equations are presented. If the usual linear equations are used, the main limitation, in the case of oscillatory shear only, is that the frequency of measurement should be below 0.016 |
*|/(r
2
–r
1
)2. Here |
*| is the modulus of the complex viscosity, is the density of the liquid andr
1
andr
2
are the radii of the cylinders. Furthermore it is shown that there is a small error in the numerical factor of the usually applied equations. The calculations are set up in such a way that extension to higher harmonics follows in a natural way. An experimental example illustrates the use of the derived equations. 相似文献
180.
V. Yu. Filinovskii 《Russian Journal of Electrochemistry》2006,42(12):1319-1324
Identity of mathematical problems concerning calculation of the distribution of reactants’ concentrations and the current near the surface of a nonuniform (strip) electrode and distribution of displacements and forces in the case of an elastic layer “antiplane” deformation caused by the punch action. Formulas for calculating the current at a strip electrode are derived for various ratios between the electrode width and the diffusion layer thickness by means of asymptotic methods designed for calculating problems of mechanical contact interactions. It is noted that calculations of the diffusion current for involved activity distributions at the electrode surface may benefit from asymptotic methods of mechanics of contact interactions. 相似文献