Spectral changes in the fluorescence of chlorophyll during photosynthesis induction

With the help of a light-emitting diode with a radiation maximum at 407 nm and an S-2000 UV-VIS spectrometer connected with a computer, the spectral changes in the fluorescence of chlorophyll from acacia leaves (Acacia sp.) preliminarily subjected to a dark adaptation are studied. It is found that, in the slow induction phase, the Kautsky effect manifests itself in the “compression” of the intensity of the chlorophyll fluorescence spectrum, with this spectrum exponentially approaching the steady-state shape with a time constant of 10–20 s. Once the steady-state fluorescence spectrum of chlorophyll was established, the amount of energy delivered to the upper singlet level is one and a half times greater than at 735 nm. The ratio between the energies spent for photochemical processes of photosynthesis and for fluorescence depends on the wavelength and the instant of time of the induction period. In the steady-state state of the chlorophyll fluorescence, the values of this ratio at 685 and 735 nm are equal to 5.9 and 3.4, respectively.     

Existence of the stationary solution of a Rayleigh-type equation

A fluid flow along a semi-infinite plate with small periodic irregularities on the surface is considered for large Reynolds numbers. The boundary layer has a double-deck structure: a thin boundary layer (“lower deck”) and a classical Prandtl boundary layer (“upper deck”). The aim of this paper is to prove the existence and uniqueness of the stationary solution of a Rayleigh-type equation, which describes oscillations of the vertical velocity component in the classical boundary layer.     

Conservation laws, hierarchy of dynamics and explicit integration of nonholonomic systems

This paper can be regarded as a continuation of our previous work [1, 2] on the hierarchy of the dynamical behavior of nonholonomic systems. We consider different mechanical systems with nonholonomic constraints; in particular, we examine the existence of tensor invariants (laws of conservation) and their connection with the behavior of a system. Considerable attention is given to the possibility of conformally Hamiltonian representation of the equations of motion, which is mainly used for the integration of the considered systems.      

Propagation of weakly nonlinear disturbances of the interface between two layers of fluid

The dynamics of internal waves of small but finite amplitude in a two-layer fluid system bounded by rigid horizontal surfaces at bottom and top is investigated theoretically. For linear disturbances of the fluid interface the authors propose a polynomial approximation of the dispersion relation which has the same asymptotics as the exact formula in the limiting situations of very long and short waves. In the case of three-dimensional, weakly nonlinear disturbances of slowly varying shape (in the coordinate system moving with the wave) an equation like the wave equation is derived. This equation has Stokes solutions coinciding with the well-known results for infinitely deep layers. For fairly long disturbances solitary solutions of the model wave equation which fit the experimental data are determined. Novosibirsk. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.1, pp. 125–131, January–February, 1994.     

Copper,cobalt, and nickel complexes with unsymmetrical porphyrazines based on 3,6-di(hexadecyloxy)phthalonitrile and anthraquinone-2,3-dicarboxylic imide. Synthesis and spectral properties

Copper, cobalt, and nickel complexes with А3В, ААВВ и АВАВ unsymmetrical porphyrazines have been synthesized via the reaction between 3,6-di(hexadecyloxy)phthalonitrile (component А), anthraquinone-2,3-dicarboxylic imide (component В), and the corresponding metal acetate in the presence of urea. Spectral properties of the synthesized compounds have been studied.     

Temperature dependence of protonic conductivity of porous glasses saturated with solutions of cesium dihydroorthophosphate in orthophosphoric acid

Wide-pore-glass plates saturated with solutions of cesium dihydroorthophosphate in orthophosphoric acid demonstrate a monotonic rise in the protonic conductivity in the temperature range 373–523 K, with σ ≥ 10^–2 Ω^–1 cm^–1 reached.     

The complex Eu(phen)L3��5CH2Cl2 (HL is 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)propane-1,3-dione): synthesis, crystal structure, and luminescent properties

A reaction of Eu(NO₃)₃·6H₂O with the novel heterocyclic ligand 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)propane-1,3-dione and 1,10-phenanthroline in the presence of NaOH gave the complex Eu(phen)L₃·5CH₂Cl₂. The crystal structure of the complex was determined by single-crystal X-ray diffraction. The coordination polyhedron {EuO₆N₂} is a tetragonal antiprism. The complex shows bright orange-red luminescence in both the solid state and solution.     

Study of the electronic spectra of sydnones and sydnoneimines

The absorption spectrum of 3-methylsydnone and the luminescence spectra of 3-methyl- and 3-phenylsydnone and 3-methylsydnoneimine hydrochloride were interpreted on the basis of calculations by the Pariser-Parr-Pople method with allowance for a correction for the solvent effect.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 53–55, January, 1976.     

Skeletal Sublattices of Heavy Components As a Basis of Stability of Crystal Structures

Crystallography Reports - A crystallographic structural analysis of low- and high-temperature phases of BaSi2O5 and Na3SO4F compounds has been carried out in order to confirm the thesis that the...