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81.
82.
Low concentration of aliphatic mercaptan increase the quantum yield of photoreduction of benzophenone by 2-butylamine, nearly to the theoretical maximum value. It is proposed that the effect arises from catalysis by mercaptain of transfer of hydrogen from the amine radical cation to the ketyl radical anion in the charge-transfer of hydrogen complex. 相似文献
83.
Saul Barshay Patrick Heiliger Dieter Rein 《Zeitschrift fur Physik C Particles and Fields》1991,52(3):415-419
Using a new form for the diffractive amplitude, we show the possibility of a local increase above asymptotic behavior in the \(\bar p\) (p)?p total cross section well up in the TeV range with values of about 180 mb reached at 100 TeV and 316 mb at 1000 TeV. Use of this locally, relatively strongly rising cross section in the dispersion relation leads to evaluation of the real to imaginary part ratio ?, for the forward scattering amplitude up into the TeV range. This quantity increases; we obtain ?=18% at 40 TeV. On the basis of a physical picture involving the growth of average multiplicities, it appears possible that asymptotic, bounded growth for the cross section may be reached only at collision energies in the vicinity of 1000 TeV. In this domain, certain global measures of partonic behavior come close to the behavior of the produced physical hadrons. 相似文献
84.
Abstract— Growing wheat seedlings in the presence of BASF 13.338 [4-chloro-5-dimethylamino-2-phenyl-3(2H)pyridazinone], a PS II inhibitor of the pyridazinone group, brought about notable changes in the structure and functioning of photosynthetic apparatus. In BASF 13.338 treated plants, there was a decrease in the ratio of Chi a/Chl b, an increase in xanthophyll/carotene ratio and an increase in the content of Cyt b 559 (HP + LP). Chl/p700 ratio increased when measured with the isolated chloroplasts but not with the isolated PS I particles of the treated plants. The SDS-PAGE pattern of chloroplast preparations showed an increase in the CPII/CP I ratio. The F685/F740 ratio in the emission spectrum of chloroplasts at -196°C increased. The difference absorption spectrum of chloroplasts between the control and the treated plants showed a relative increase of a chlorophyll component with a peak absorption at 676 nm and a relative decrease of a chlorophyll component with a peak absorption at 692 nm for the treated plants. The excitation spectra of these chloroplast preparations were similar. Chloroplasts from the treated plants exhibited a greater degree of grana stacking as measured by the chlorophyll content in the 10 K pellet. The rate of electron transfer through photosystem II at saturating light intensity in chloroplast thylakoids isolated from the treated plants increased (by 50%) optimally at treatment of 125 μM BASF 13.338 as compared to the control. This increase was accompanied by an increase in (a) I50 value of DCMU inhibition of photosystem II electron transfer; (b) the relative quantum yield of photosystem II electron transfer; (c) the magnitude of C550 absorbance change; and (d) the rate of carotenoid photobleaching. These observations were interpreted in terms of preferential synthesis of photosystem II in the treated plants. The rate of electron transfer through photosystems I and through the whole chain (H2O → methyl viologen) also increased, due to an additional effect of BASF 13.338, namely, an increase in the rate of electron transfer through the rate limiting step (between plastoquinol and cytochrome f). This was linked to an enhanced level of functional cytochrome f. The increase in the overall rate of electron transfer occurred in spite of a decrease in the content of photosystem I relative to photosystem II. Treatment with higher concentrations (> 125 μM) of BASF 13.338 caused a further increase in the level of cytochrome f, but the rate of electron transfer was no greater than in the control. This was due to an inhibition of electron transfer at several sites in the chain. 相似文献
85.
Saul T. Epstein 《International journal of quantum chemistry》1987,31(3):425-427
It is made clear that two different statements in the literature concerning energy derivatives are completely compatible by deriving them as two different interpretations of the same equation. Some other aspects of these results are also discussed. 相似文献
86.
Campos-Fernández CS Thomson LM Galán-Mascarós JR Ouyang X Dunbar KR 《Inorganic chemistry》2002,41(6):1523-1533
A homologous series of dinuclear compounds with the bridging ligand 2-(2-pyridyl)-1,8-naphthyridine (pynp) has been prepared and characterized by X-ray crystallographic and spectroscopic methods. [Mo(2)(O(2)CCH(3))(2)(pynp)(2)][BF(4)](2) x 3CH(3)CN (1) crystallizes in the monoclinic space group P2(1)/c with a = 15.134(5) A, b = 14.301(6) A, c = 19.990(6) A, beta = 108.06(2) degrees, V = 4113(3) A(3), and Z = 4. [Ru(2)(O(2)CCH(3))(2)(pynp)(2)][PF(6)](2) x 2CH(3)OH (2) crystallizes in the monoclinic space group C2/c with a = 14.2228(7) A, b = 20.3204(9) A, c = 14.1022(7) A, beta = 95.144(1) degrees, V = 4059.3(3) A(3), and Z = 4. [Rh(2)(O(2)CCH(3))(2)(pynp)(2)][BF(4)](2) x C(7)H(8) (3) crystallizes in the monoclinic space group C2/c with a = 13.409(2) A, b = 21.670(3) A, c = 13.726(2) A, beta = 94.865(2) degrees, V = 3973.9(8) A(3), and Z = 4. A minor product, [Rh(2)(O(2)CCH(3))(2)(pynp)(2)(CH(3)CN)(2)][BF(4)][PF(6)] x 2CH(3)CN (4), was isolated from the mother liquor after crystals of 3 had been harvested; this compound crystallizes in the triclinic space group, P1 with a = 12.535(3) A, b = 13.116(3) A, c = 13.785(3) A, alpha = 82.52(3) degrees, beta = 77.70(3) degrees, gamma = 85.76(3) degrees, V = 2193.0(8) A(3), and Z = 2. Compounds 1-3 constitute a convenient series for probing the influence of the electronic configuration on the extent of mixing of the M-M orbitals with the pi system of the pynp ligand. Single point energy calculations performed on 1-3 at the B3LYP level of theory lend insight into the bonding in these compounds and allow for correlations to be made with electronic spectral data. Although purely qualitative in nature, the values for normalized change in orbital energies (NCOE) of the frontier orbitals before and after reduction are in agreement with the observed differences in reduction potentials as determined by cyclic voltammetry. 相似文献
87.
A simple expression derived from the Morse potential allows X-H bond dissociation energies to be estimated from the quadratic stretching force constants obtained in ab initio computations. Agreement with experiment is excellent for C-H bonds, except when the radical is stabilized by π-conjugative effects, in which case the bond dissociation energy is overestimated. The procedure also fails to estimate ionic dissociation energies. 相似文献
88.
Saul Barshay 《Zeitschrift fur Physik C Particles and Fields》1986,32(4):513-516
In high-energypp ( \((\bar pp)\) ) collisions, the average value of backward produced charged particles, taken at fixed number of forward produced particlesn F, depends significantly uponn F. This correlation is absent ine + e ? annihilation at present energies. We relate these facts using the picture of the broadpp multiplicity distribution which arises from the incoherent superposition of narrow distributions from all impact parameters. 相似文献
89.
90.