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71.
F. Akbarian A. Lin B.S. Dunn J.S. Valentine J.I. Zink 《Journal of Sol-Gel Science and Technology》1997,8(1-3):1067-1070
Biological activity of cholinesterases can be determined by optically monitoring the enzymatic reaction with indophenyl acetate,
(N-4′-acetoxyphenyl)-4-quinone imine. At pH 8.0 cholinesterases hydrolyze this yellow dye to yield a blue reaction product.
Cholinesterase inhibitors reduce the rate of this hydrolysis. Thus, by monitoring absorbance of the hydrolysis product at
its maximum (630 nm) as a function of time, reaction rates of both cholinesterase activity and cholinesterase inhibition may
be quantified spectroscopically. Using this technique, we measured the enzymatic activity of butyrylcholinesterase (BuChE)
molecules encapsulated in tetramethyl orthosilicate (TMOS) silicate gel-glass prepared by hydrolysis and condensation. This
activity is reduced, in a concentration-dependent manner, by the reversible cholinesterase inhibitors 1,5-bis(4-allyldimethyl-ammoniumphenyl) pentan 3-one dibromide (BADAPP) and 9-amino-1,2,3,4-tetrahydroacridine (THA; tacrine, Cognex).
The gel-glasses are rigid, and compact, transparent and porous enough to allow reagents to diffuse in and out. 相似文献
72.
Arthur E. Hill und William A. H. Zink 《Fresenius' Journal of Analytical Chemistry》1909,48(7-8):448-456
Ohne ZusammenfassungAus dem Englischen übersetzt von der Redaktion.(Mitteilung aus dem Havemeyer Chemischen Laboratorium der Universität New York.) 相似文献
73.
Julius Zink und Friedr Hollandt 《Fresenius' Journal of Analytical Chemistry》1927,71(10):386-388
Ohne Zusammenfassung 相似文献
74.
The first values of the absolute triboluminescence intensity, in units of photons/mol, are reported for molecular crystals and salts. The values range from 5 × 1016 photons/mol for cholesteryl salicylate to 6.2 × 1010 photons/mol for magnesium sulfate. The mechanical yield of triboluminescence is defined and the lower limit is determined. 相似文献
75.
76.
Carl Amthor und Julius Zink 《Fresenius' Journal of Analytical Chemistry》1892,31(1):381-383
Ohne Zusammenfassung 相似文献
77.
Nelsen SF Weaver MN Zink JI Telo JP 《Journal of the American Chemical Society》2005,127(30):10611-10622
The optical spectra of nine dinitroaromatic radical anions (1,2- and 1,4-dinitrobenzene, 1,5- and 2,6-dinitro naphthalene, 4,4'-dinitrobiphenyl, 2,7-dinitro-9,9-dimethylfluorene, 2,6-dinitroanthracene, and 2,7- and 1,8-dinitrobiphenylene) in dimethylformamide are reported and analyzed. All have delocalized charge distribution, as demonstrated by the vibrational fine structure that is observed in their optical spectra: All show lowest energy absorption bands that correspond to an alpha-homo (highest occupied molecular orbital) to alpha-lumo (lowest unoccupied) transition, as shown by Koopmans-based UB3LYP calculation of the orbital separation of the neutral at the geometry of the radical anion. These single-point calculations are shown to be significantly more accurate for five of these compounds than the much more complex and expensive TD-DFT method. The two-state model should not be used to estimate the electronic coupling in delocalized intervalence compounds such as these. Neighboring orbital estimation of the electronic couplings show that using the two-state model greatly underestimates electronic coupling here. 相似文献
78.
E. C. C. Vasconcellos S. C. Zerbetto L. R. Zink K. M. Evenson 《International Journal of Infrared and Millimeter Waves》2000,21(5):731-737
Twenty-seven new far-infrared laser lines from the isotopomers of methanol: 12CD3OH, 12CH3OD, and 12CH2DOH, were obtained by optically-pumping the molecules with an efficient cw CO2 laser. The CO2 laser provided pumping from regular, sequence, and hot-band CO2 laser transitions. The 2-m long far-infrared cavity was a metal-dielectric waveguide closed by two, flat end mirrors. Several short-wavelength (below 100 m) lines were observed. The frequencies of 28 laser lines observed in this cavity (including new lines and already known lines) were measured with a fractional uncertainty limited by the fractional resetability of the far-infrared laser cavity, of 2 parts in 107. 相似文献
79.
An analytical expression is derived for the decrease in the absorption cross section that occurs when two molecular electronic states are coupled by spin-orbit coupling. The loss of intensity, or interference dip, is common in the spectra of metal compounds. The derivation is based on a coupling of a single forbidden donor state to a broadened harmonic acceptor potential, and leads to simple analytical expressions. The new expressions give line shape functions different from those in the commonly used Fano antiresonance interpretation and are based on interpretable molecular properties. 相似文献
80.
E. C. C. Vasconcellos M. D. Allen L. R. Zink K. M. Evenson 《International Journal of Infrared and Millimeter Waves》2000,21(5):725-730
A far-infrared laser cavity designed to favor short-wavelength laser lines was used to generate optically-pumped far-infrared laser radiation. New far-infrared laser lines were discovered in hydrazine, heavy water, ammonia, and several short-wavelength lines previously discovered in methanol were observed. Wavelength, frequency, and relative intensity measurements were performed on laser lines in the wavelength range 42.4 to 253.7 m. Each far-infrared frequency measurement was obtained by mixing the far-infrared radiation with radiation from two reference CO2 lasers and from a microwave synthesizer in a metal-insulator-metal diode. The pump laser was a high-Q Fabry Perot resonator oscillating on 275 grating-selected laser lines including regular, sequence, and hot band lines. 相似文献