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1.
Hornstein MK Bajaj VS Griffin RG Temkin RJ 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2006,34(3):524-533
We report the regulated continuous-wave (CW) operation of a second harmonic gyrotron oscillator at output power levels of over 8 W (12.4 kV and 135 mA beam voltage and current) in the TE(0,6,1) mode near 460 GHz. The gyrotron also operates in the second harmonic TE(2,6,1) mode at 456 GHz and in the TE(2,3,1) fundamental mode at 233 GHz. CW operation was demonstrated for a one-hour period in the TE(0,6,1) mode with better than 1% power stability, where the power was regulated using feedback control. Nonlinear simulations of the gyrotron operation agree with the experimentally measured output power and radio-frequency (RF) efficiency when cavity ohmic losses are included in the analysis. The output radiation pattern was measured using a pyroelectric camera and is highly Gaussian, with an ellipticity of 4%. The 460-GHz gyrotron will serve as a millimeter-wave source for sensitivity-enhanced nuclear magnetic resonance (dynamic nuclear polarization) experiments at a magnetic field of 16.4 T. 相似文献
2.
V. R. Khabibulin A. V. Kulik I. V. Oshanina L. G. Bruk O. N. Temkin V. M. Nosova Yu. A. Ustynyuk V. K. Bel’skii A. I. Stash K. A. Lysenko M. Yu. Antipin 《Kinetics and Catalysis》2007,48(2):228-244
The formation mechanism of the active catalyst in the oxidative carbonylation of terminal alkynes at the ≡C-H bond has been investigated for the catalytic system Pd(OAc)2-PPh3-p-benzoquinone (Q)-MeOH. It has been demonstrated by NMR spectroscopy, X-ray crystallography, and kinetic measurements that the catalytically active palladium is in the oxidation state 0 and is bound into complexes stabilized by p-benzoquinone (PdL2Q, where L = PPh3). A mechanism is suggested for the catalytic process, which includes the formation of the complex PdL2Q, the oxidative addition of the alkyne to this complex at the ≡C-H bond, the insertion of CO into the Pd-C bond, and steps in which hydride hydrogen is intramolecularly transferred to the p-quinone. 相似文献
3.
The action of ultra violet rays of 260 nm on aqueous solutions of bases, nucleosides and nucleotides of DNA at 77°K is studied by electron spin resonance. It is shown that the free radicals observed are similar, with a few noteworthy exceptions to those induced by X-rays, under the same conditions of temperature, in the solid state. Contrary to what might be excepted on the basis of the results obtained by X-rays, the variation in the yield in paramagnetic centres in each sequence studied does not seem to be important. 相似文献
4.
ALBERT VAN DE VORST 《Photochemistry and photobiology》1971,13(4):321-336
Abstract— –The photosensitization of amino acids by proflavine is studied using the technique of electron spin resonance spectroscopy. The analysis of the line shape as a function of the incident microwave power (both in the presence and absence of oxygen) and the dependence of the numbers of free radicals on the intensity of the incident light allow one to suggest that two types of radicals are formed. One is formed by a biphotonic process, the nature of the radicals being the same as in the case of ionising radiation, while the other is probably the RO2 radical formed as a result of photodynamic action. 相似文献
5.
BARB FLORIN DAN; IONESCU VLAD; KONING WILLEM DE 《IMA Journal of Mathematical Control and Information》1994,11(4):277-309
In this paper, we deal with the digital output-measurement-feedbackH control problem for Pritchard-Salamon infinite-dimensionalsystems with unbounded input and output operators. A discretePopov-theory-based solution is given in terms of the solvabilityof Kalman-Szegö-Popov-Yakubovitch systems associated withthe equivalent discrete-time time-invariant system obtainedby lifting the T-periodic continuous-time system. 相似文献
6.
7.
The theory of the isotropic Raman line broadening is compared with gas and liquid experimental data. The effect of rotational structure narrowing with increasing density is confirmed. The vibrational relaxation (dephasing) contribution to the spectral broadening has been extracted, it being essential in liquid phase. It has been shown to be due to weak collisions and to increase proportionally to their frequency. 相似文献
8.
9.
Nitroxyl-radical rotational-mobility anisotropy effects in magnetization-transfer electron spin echo
Formulas have been derived for the magnetization transport in the limiting case of uniaxial rotation and any reorientation correlation (Ivanov-Valiev model). Numerical calculations have been performed for particular situations. Rotational-mobility anisotropy makes itself felt when the difference in the angles between the symmetry axis for the nitroxyl radical magnetic tensor and the rotation axis is less than 30° or close to 90°.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 6, pp. 647–653, November–December, 1989. 相似文献
10.
I. S. Kislina M. Yu. Kulikova S. G. Sysoeva O. N. Temkin 《Russian Chemical Bulletin》1994,43(10):1626-1629
The acidity functionsH
0
s of HCl solutions in EtOH-H2O solvents containing 1.09, 3.0, and 5.0% water have been measured at 25 and 40 °C by the indicator method. The concentration of HCl changes from 10–2 to 36m. Nitroanilines, for which a protonation mechanism is realized in the studied systems, were used as indicators.For each solvent,H
0
s is temperature independent atm
HCl < 4, and acidity atm
HCl > 4 mol L–1 increases more rapidly at 25 °C than at 40 °C. The acidity functions of aqueous and water-ethanol solutions of HCl were compared, and the concentrations of proton solvates of different compositions and their relative protonating ability were evaluated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1722–1725, October, 1994.This work was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-18356). 相似文献