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101.
Bernard A. Olsen Dennis H. Evans I. Agranat 《Journal of Electroanalytical Chemistry》1982,136(1):139-148
The electrochemical reduction of several substituted bianthrones is similar to that of the parent compound. 3,3′-Dimethylbianthrone (II), 3,3′-di-n-heptylbianthrone (III). 3,3′-dimethoxybianthrone (IV) and 1,1′-dimethylbianthrone -(V) were studied in dimethylformamide using cyclic voltammetry and transmission mode spectroelectrochemistry. For each compound the low temperature A form is reduced in a two-electron irreversible reaction to a twisted dianion, B2?. Upon oxidation, B2? forms first B, then B, whose spectral properties are identical to those of the high-temperature thermochromic form of the bianthrones. Rate constants for the B-A reaction were determined for each compound. The reduction of 2,3,2′,3′-dibenzo-7,7′-dimethylbianthrone (VI) showed somewhat different features which were tentatively interpreted in terms of redox catalysis. 相似文献
102.
S.D. Olsen R.A. Edge R.G. Böhmer 《Spectrochimica Acta Part B: Atomic Spectroscopy》1982,37(4):303-308
Synthetic heavy mineral concentrate standards for calibrating a d.c. arc emission spectrometer were prepared from specpure oxides and compounds. X-ray diffraction and scanning electron microscope studies of the heat-treated synthetic matrix showed that minerals which occurred in natural heavy mineral concentrates were formed. An optimum sintering time of 4 hr was established by monitoring X-ray diffraction peaks of minerals undergoing alteration or being formed in the synthetic base. 相似文献
103.
104.
105.
Three prominant peaks are observed in Kα X-ray spectra of both Al and Si at energies below the characteristic Kα1,2 lines. These emission lines were produced by 30 MeV oxygen bombardment and recorded with a crystal spectrometer. The exact origin of these lines is not understood. 相似文献
106.
The mechanism of Lengyel, Li, Kustin, and Epstein (J. Am. Chem. Soc. 1996, 118, 3708) for the oscillatory chlorine dioxide-iodide reaction accurately models the reaction in closed and open systems. We investigated whether this mechanism minus the single reaction involving chlorine dioxide models the chlorite-iodide reaction equally well. It agrees qualitatively with clock reaction results. As for open system dynamics, the mechanism predicts the existence of two steady states and bistability in very nearly the same regions where these features are found experimentally in the pH range 2-4. A discrepancy in the range of bistability emerges as pH decreases, and it cannot be remedied by taking into account chlorous acid decomposition. That we were unable to locate an oscillatory region is of greater significance. Because the chlorite-iodide reaction is sensitive to mixing effects, we incorporated a two-parameter model of imperfect mixing but still found no oscillations at physically reasonable parameter values. These discrepancies strongly suggest that to obtain predictive utility for the chlorite-iodide reaction, revision of the chlorine dioxide-iodide mechanism is required. 相似文献
107.
108.
The interaction between solitary wave solutions to a double sine-Gordon equation is examined numerically. Depending on the velocity, formation of breather-like modes or quasi solitonic behaviour are observed when a 2δ-kink interact with a 2π-antikink. As a result of collision between a (2π-2δ)-kink and a (2π-2δ)-antikink two 2δ-kink-antikink pairs always appear. 相似文献
109.
F. Geoffrey N. Cloke Malcolm L.H. Green Patrick J. Lennon 《Journal of organometallic chemistry》1980,188(3):C25-C26
Cocondensation of cycloheptatriene with zirconium or hafnium vapours gives, after vacuum pyrolysis of the reaction mixture the diamagnetic d2 compounds [m(η-C7H7)(η-C7H9)]. 相似文献
110.