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51.
The interaction of water-soluble cationic 5,10,15,20-tetrakis(4-N-methyl pyridyl) porphyrin (H2TMPyP4) with some mono-and polynucleotides is studied by time-resolved and steady-state fluorescence spectroscopy, as well as by steady-state absorption spectroscopy. The fluorescence decay kinetics are analyzed by reconstructing the decay time distributions, which made it possible to describe in more detail than previously the complexes formed due to the interaction. The main effect of binding of H2TMPyP4 adenosine 5′-monophosphate and to poly(dA-dT)2 is shown to be an increase in the fluorescence lifetime from 4.6 ns in the solution to 8.3 and 12.3 ns, respectively. This effect is explained by a less polar (in comparison with water) environment of porphyrin in complexes, which leads to a decrease in the quenching action of the intramolecular charge transfer state between the porphyrin macrocycle and methyl pyridyl groups. In the case of complex formation with guanine-containing nucleotides (guanosine 5′-monophosphate and poly(dG-dC)2), the effect of decrease in the quenching action of the intramolecular charge transfer state caused by a decrease in the medium polarity is superimposed by a stronger effect of decrease in the fluorescence lifetime of porphyrin as a result of intermolecular electron transfer from guanine to excited porphyrin. A high sensitivity of this intermolecular quenching to the mutual arrangement of the electron donor and the electron acceptor makes it possible to reveal four types of complexes between H2TMPyP4 and guanosine 5′-monophosphate, which differ in the positions of four broad peaks in the porphyrin fluorescence decay time distribution (0.1, 0.7, 2.4, and 6.1 ns). For the complex with poly(dG-dC)2, a narrow peak at 2.8 ns prevails in the fluorescence decay time distribution, with the contributions from two additional narrow peaks at 1.0 and 6.2 ns being small. 相似文献
52.
53.
54.
V. V. Petrov 《Journal of Mathematical Sciences》1992,61(1):1905-1906
Upper bounds are obtained for the absolute moments of order p>1 of sums of independent random variables.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akademii Nauk SSSR, Vol. 177, pp. 120–121, 1989. 相似文献
55.
Vladimir V. Veremey Yury A. Tuchkin 《International Journal of Infrared and Millimeter Waves》1997,18(4):909-938
An analysis of resonances of scattering from multi-element grating formed by a finite number of resonant elements is presented.
It has been shown that gratings with three and more elements on its period can support the π-mode. The π-mode of a grating
is characterized by the existence of the regions in the vicinity of the grating and along its period where the electromagnetic
field has opposite phases. The existence and excitation of the π-mode in finite gratings with resonant cells formed by several
scatterers having open cavities have been studied. The particular case of the grating with cells formed by three identical
slotted cylinders has been considered in detail. An application of gratings which support the π-mode in electron-vacuum oscillators
of millimeter waves for efficient deceleration of electrons and extracting energy from electron beam is discussed. 相似文献
56.
We have determined the various parameters of the electric field gradient (EFG) for different Fe-oxygen configurations. This was achieved by analyses of a variety of spectra using a procedure which allows fitting of all spectra of oriented 1-2-3 compounds obtained at different tilt angles β simultaneously, taking into account the degree of texture. The use of a point charge model is invalidated because of the high degree of estimated covalence. The Mössbauer parameters are rationalized. The absence of any observed anisotropy of the mean square displacement of the dopant at the Cu(1) site is rather intriguing. 相似文献
57.
V. P. Nesterenko K. P. Aref'ev V. I. Merkulov A. A. Kondratyuk A. V. Petrov 《Russian Physics Journal》2003,46(2):157-160
The electric strength of a polyoxide mass obtained on the surface of hard alloy composite materials by their high-temperature heating in an electric furnace with direct access of atmospheric air is studied. 相似文献
58.
R. M. Vlasova N. V. Drichko B. V. Petrov V. N. Semkin E. I. Zhilyaeva R. N. Lyubovskaya I. Olejniczak A. Kobayashi H. Kobayashi 《Physics of the Solid State》2004,46(11):1985-1993
Polarized reflectance and optical conductivity spectra of single crystals of two new isostructural organic conductors based
on the BEDT-TSeF molecule, namely, the κ-(BETS)4Hg2.84Br8 superconductor (T
c
=2 K) and the κ-(BETS)4Hg3Cl8 metal, which undergoes a smooth transition to the dielectric state near 35 K, have been obtained in the spectral region 700–6500
cm−1 at temperatures of 300–15 K. At 300 K, the spectra of both compounds are nearly identical and differ from the Drude spectrum
characteristic of metals. The nature of the observed difference is discussed, and the spectra are described in terms of a
cluster approach with inclusion of electron-electron correlations in the Hubbard approximation combined with the Drude model.
The parameters of the theory were determined, including the electron transfer integrals between molecules in a cluster. The
spectra in the conducting plane of the crystals were found to be essentially anisotropic, which should be assigned to specific
features of in-plane interaction between molecules. The spectra of the superconductor and the metal become increasingly different
as the temperature is lowered. The spectra of the metal obtained for T<150 K exhibit splitting of the broad electronic maximum in the mid-IR region into two bands, which is accompanied by a splitting
of a vibronic feature deriving from electron interaction with intramolecular BETS vibrations of ν3(A
g
) symmetry. No such splitting is observed in the superconductor spectra with decreasing temperature.
__________
Translated from Fizika Tverdogo Tela, Vol. 46, No. 11, 2004, pp. 1921–1929.
Original Russian Text Copyright ? 2004 by Vlasova, Drichko, Petrov, Semkin, Zhilyaeva, Lyubovskaya, Olejniczak, A. Kobayashi,
H. Kobayashi. 相似文献
59.
60.