Features of Functionalization of MCM-41 Silica Mesoporous Molecular Sieves during Their Template Synthesis

We have shown that functionalization of MCM-41 mesoporous molecular sieves during their template synthesis using the effect of solubilization of organic hydrophobic co-condensing compounds makes it possible to obtain highly ordered mesoporous molecular sieves, with concentrations of vinyl or allyl groups covalently bonded to the surface of the silica matrix of about 3.5 mmol/g, which after sulfonation have acidic properties and exhibit catalytic activity in the process of ethyl tert-butyl ether synthesis.     

EXAFS Study of Ph3GeMn(CO)5 Structure Evolution on Exposure to X-Radiation

Ge K-edge and Mn K-edge EXAFS spectroscopy was used to study changes in the local environment of germanium and manganese atoms during radiolysis of the Ph₃GeMn(CO)₅ complex. On exposure to X-radiation, the metal complex undergoes a number of transformations depending on the radiant exposure (). It was shown that at = (6–8) × 10⁶ J/m², the initial metal complex decomposes into the [Ph₃Ge] and [Mn(CO) _n ] fragments with partial detachment of the CO groups from Mn atoms. When = 1.3 × 10⁷ J/m², Mn atoms lose completely the CO groups to form finely dispersed metal nanoparticles, which interact with the surrounding atoms (carbon or nitrogen). With further increase in , the local environment of the Mn atoms no longer changes. The Ge atoms remain coordinated to the Ph groups as increases up to 2 × 10⁷ J/m², but starting with = 1.6 × 10⁷ J/m², metal–metal bonds are formed; subsequently, the amount of this phase increases and when = 2.6 × 10⁸ J/m², it becomes predominant. Since manganese and germanium atoms lose their ligands at different values, one can conclude that germanium and manganese nanoparticles are the final products in the radiolysis of Ph₃GeMn(CO)₅.     

New octahedral Zn<Superscript>II</Superscript> and Cd<Superscript>II</Superscript> complexes based on azo derivatives and azomethines of pyrazole-5-thione

New metal chelates of Zn^II and Cd^II (ML₂) based on (4Z)-3-methyl-1- phenyl-5-thioxo-1,5-dihydro-4-H-pyrazol-4-one quinolin-8-ylhydrazone (HL¹) and (4Z)-5- methyl-2-phenyl-4-[(quinolin-8-ylimino)methyl]-2,4-dihydro-3H-pyrazole-3-thione (HL²) were synthesized. The structures of the metal chelates were studied by EXAFS and NMR (¹H, ¹³C, and ¹¹¹Cd) spectroscopy. The structure of the Cd(L¹)₂ complex was established by X-ray diffraction analysis. The complexes have pseudooctahedral structures with the N₄S₂ ligand environment.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 623–629, March, 2005.     

Implicit linear time‐dependent differential‐difference equations and applications

The paper deals with the differential‐difference equation in a Banach space. The operator coefficient of the delay‐free derivative is allowed to be degenerate. Existence and uniqueness theorems are proved under the main assumption that for every the point is a polar singularity of the resolvent . The results are applied to evolution problems of microwave circuits. Copyright © 2000 John Wiley & Sons, Ltd.     

Investigation of the characteristics of low-voltage electroluminescent films of ZnS · Mn excited by pulses

The brightness waves resulting from excitation by square pulses, the time constant of the flash initiation and of the electroluminescence decay, the average brightness of low-voltage ZnS · Mn films as a function of the voltage-pulse duration, the frequency of these pulses, and their amplitude and polarity were investigated. The equivalent circuit of cells with such electroluminescent films is discussed. A flash can be observed when the first of a series of monopolar pulses are applied to the cell or when the polarity of the pulses is changed. It was established that the average brightness of the electroluminescence from ZnS·Mn films can be increased considerably when pulses with varying polarity are applied instead of unipolar pulses.By excitation with pulses of varying polarity, one can achieve an average brightness of not less than 15–20 nits for a pulse amplitude greater than or equal to 30 volts, a pulse duration greater than or equal to 20 sec., and a pulse repetition frequency greater than or equal to 200 cps.In conclusion, the authors express their thanks to V. I. Kislyuk and I. Yu. Shablii for their help in the experiments, and to Dr. M. P. Lisitsa for her interest.     

Catalytic and asymmetrizing activity of mixed copper-nickel catalysts,deposited on aerosil,in the hydrogenation of acetylacetone

Conclusions A mixed Cu-Ni (11) catalyst, deposited on aerosil and modified with D-(+)-tartarie acid, was obtained, which is active in theselective stereoselective hydrogenation of acetylacetone to the (-)-ketol. The optical yield of the ketol is 9.1% at 133°.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 680–682, March, 1977.     

Synthesis and photochromic properties of spiroanthrooxazine

1,3,3-Trimethylspiro[indoline-2,3-3H-anthraceno[2,1-b][1,4]oxazine] was synthesized. The compound has photochromic properties in solutions and in polymeric matrices. It was found from the spectral data that the colored form of the spiroanthrooxazine exists in a quinoid form and is characterized by a positive solvatochromic effect.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1521–1525, July, 1990.     

On configurations of subspaces of a Hilbert space with fixed angles between them

We investigate the set of irreducible configurations of subspaces of a Hilbert space for which the angle between every two subspaces is fixed. This is the problem of *-representations of certain algebras generated by idempotents and depending on parameters (on the set of angles). We separate the class of problems of finite and tame representation type. For these problems, we indicate conditions on angles under which the configurations of subspaces exist and describe all irreducible representations.Translated from Ukrainskyi Matematychnyi Zhurnal, Vol. 56, No. 5, pp. 606–615, May, 2004.