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It has been shown that, at elevated temperatures (∼350°C), the most distinct response to H2 from the thin film structure Pt/WO x /SiC is achieved at registration of change in voltage for the reverse branch of a current-voltage characteristic. Comparative studies of electric current conduction through the structure and over its surface (with deposited Pt film) have led to the conclusion that a change in properties of the Pt/WO x and WO x /SiC interfaces under action of H2 mostly determines efficiency of response of the structure in the case of “transverse” measuring geometry. In the case of a 2% concentration of H2 in air the voltage shift for the reverse branch at a current of ∼10 μA reached 5 V against 2 V on the forward branch and “planar” geometry of measurements.

Modification of biologically active cycloalkaneindoles by incorporation of a 2-trifluoromethylimidazo[1,2-a]pyridin-6-yl fragment has been proposed and performed via the interaction with 3-fluoro-2-trifluoromethylimidazo[1,2-a]pyridines in the presence of potassium hydroxide. The action of the prepared compounds on neuronal NMDA receptors has been studied by means of radioligand binding.

A method for the modification of tetrahydrocarbazoles with the 2-(5-fluoropyridin-3-yl)ethyl fragment was suggest, which consists in the reaction of 5-fluoro-3-vinylpyridine with tetrahydrocarbazoles under conditions of fluoride ion catalysis and leads to the earlier unknown 9-[2-(5-fluoropyridin-3-yl)ethyl]-2,3,4,9-tetrahydro-1H-carbazoles. Method of radioligand binding was used to study the influence of compounds synthesized on neuronal NMDA-receptors.

Bis(dialkylamides) of phosphoryl-substituted α,ω-dicarboxylic acids were synthesized and their biological activity was studied.

A series of amides of benzodioxane-6-carboxylic and piperonylic acids have been synthesized. Biological studies showed that some of the synthesized compounds influence the central nervous system (in particular, AMPA receptors).

The stability of poly-α-olefin oils with molecular mass of from 500 to 1000 is investigated. It is found that the molecular mass, temperature, and introduction of various antioxidizers affect the thermo-oxidative stability of oils. It is shown that poly-α-olefin oils with antioxidizers can be used as liquid dielectrics.

The hygroscopicity of poly-α-olefin based oils is studied. Moisture saturation of all oils used in this study is reached by 60 h into the tests. The dependence of the hygroscopocity of the oils on the molecular mass of the oligomer is determined. The presence of functional additives in the oils does not greatly affect their hygroscopicity, while polar compounds (products of aging) sharply (almost twofold) increase the hygroscopicity.

The effect of cyclic heat treatments and diffusion of gold into silicon with inherent quenched-in donors on the electrical properties of the material is studied. An analysis of the data on slow cooling and quenching makes it possible to conclude that the mechanisms of transformation of quenched-in donors in the course of quenching and multi-cycle heat treatment with slow cooling are different and that there are two different acceptor states of gold atoms.

A method for stereospecific synthesis of allomargaritarin and other amination products of the natural alkaloid securinine was developed. Stereoselective nucleophilic addition of an amine at the double bond of the azobicyclooctane moiety of securinin was achieved by using ytterbium triflate as the catalyst. The biological activity of securining caused by adding pharmacophores to the molecule was shown to change experimentally.

Experimental results of studying the photoconductivity kinetics in silicon doped with either gold or sulfur are reported. The nonequilibrium charge-carrier concentration was generated by the effect of pulsed laser radiation. The time dependence of nonequilibrium conductivity was determined by contactless measurements from a variation in the reflected power of the microwave field. The long-term photoconductivity with the time constant of τ ≈ 1.6 ms at room temperature is observed in the silicon samples overcompensated with sulfur. Conventional short-term processes (τ ≈ 2–3 µs) characteristic of the centers with deep levels are observed in the silicon samples doped with gold. These differences are accounted for using the known data on the energy characteristics of the gold and sulfur levels in the silicon band gap and their charge states.

A positive allosteric modulator of AMPA receptors has been designed using computer-aided molecular modeling techniques. It possessed a record high experimentally confirmed potency in the picomolar concentration range and belongs to a new type of bivalent AMPA receptor ligands containing bicyclo[3.3.1]nonane scaffold. The suggested structure could serve as a basis for further optimization and development of drugs for the treatment of neurodegenerative diseases, cognition enhancement, and improvement of memory.

The influence of high-temperature annealings followed by cooling under different conditions on changes in the specific resistance and photoconductivity relaxation time in silicon and on the formation of the acceptor state of gold, when gold diffused from a layer vacuum-deposited on the surface, was studied in experiments including sequences of processes conducted using various temperatures, cooling conditions, and surface states. The experimental data are analyzed based on the concept of changes in the state of impurities present in silicon and in the corresponding dynamic and static force fields.

Dimebon in low concentrations potentiated activity of AMPA-receptors in rat cerebellar Purkinje neurons, while memantine produced only an insignificant potentiation in a small group of these cells. In cortical neurons of rat brain memantine efficiently blocked NMDA-induced currents in dimebon-insensitive neurons. By contrast, its effect was far weaker in neurons, where the blocking action of dimebon on NMDA-receptors was most pronounced. It was hypothesized that the differences in the effects of memantine and dimebon are determined by their interaction with different sites of NMDA-receptors.

Data are presented on the effect of long-term high-temperature heat treatment (750°C, 200 h; 950°C, 50 h; and 1050°C, 50 h) preceding Au diffusion on the acceptor behavior of Au in n-type Czochralski silicon. Detailed studies of Au diffusion reveal that the impurity gettering process depends strongly on the heat treatment conditions. The results are interpreted in terms of oxygen precipitation in Si.

The equations of thermally stimulated currents were derived for an exponential heating profile. The applicability of this approach was checked using experimental data for Si〈P,Au〉. The ionization energies of two trap levels in Si〈P,Au〉 were determined to be 0.25 and 0.40 eV.

Data are presented on the electrical activity of Au in Czochralski Si heat-treated and diffusion-doped under various conditions. The results are interpreted in terms of force fields responsible for changes in the concentration of electrically active centers. Long-term heat treatment between 700 and 1050°C is shown to have a significant effect on the acceptor behavior of Au in diffusion-doped Si. The concentration of Au acceptors is sensitive to the surface condition in the course of heat treatment: a tungsten coating increases the Au concentration in the bulk of diffusion-doped Si.

Visible and IR absorption spectra are studied for copper phthalocyanin (CuPc)-polyyimide composites. The composite films are obtained by vacuum codeposition of CuPc, pyromellitedianhydride, and diaminodiphenyloxide followed by temperature-induced imidization. On the basis of IR spectra it is shown that in the prepared composites imidization occurs over the whole CuPc concentration range (10–90%). From the visible spectra it is found that CuPc is deposited mainly in the form of a-microcrystals, which are destroyed during imidization to produce noncrystalline molecular aggregates. Subsequent heat treatment (320–350°C) gives rise to CuPc β-microscrystals.

A theory of signal shaping is proposed for semiconductor investigation by the method of photodeflection spectroscopy with pulse excitation that would take account of the influence of charge carrier recombination on the temperature distribution in the specimen. Quantitative computations are performed for silicon that demonstrate the change in PDS signal amplitude and shape when taking account of bulk carrier recombination. It is shown that taking account of the influence of bulk recombination discloses the possibility of obtaining additional quantitative information about the charge carrier lifetime in the specimen.

We studied the effect of delta sleep-inducing peptide on GABA receptors of hippocampal and cerebellar neurons in rats. It was shown that delta sleep-inducing peptide considerably and dose-dependently potentiates GABA-activated currents in these neurons and blocks NMDA-activated potentiation in cortical and hippocampal neurons. The peptide modulates activity of presynaptic NMDA receptors, which is seen from changes in (45)Ca(2+) uptake into synaptosomes of the brain cortex after uptake stimulation with glutamate and NMDA.

Transmembrane currents elicited by application of N-methyl-D-aspartate (NMDA), aspartate (As), or quinolinic acid (QA) were recorded from isolated unidentified neurons of the rat cortex. It was found that As and QA acted not only on NMDA-receptors: in some neurons they elicited other responses, whose characteristics suggest that As and QA act on their common receptors, different from those of NMDA type.

The effect of interleukin-1beta on presynaptic NMDA receptors was evaluated by studying NMDA-induced 45Ca2+ uptake by synaptosomes from rat brain cortex. Interleukin-1beta inhibited 45Ca2+ uptake by synaptosomes. Our results indicate that interleukin-1beta modulates presynaptic NMDA receptors and is probably involved in the regulation of synaptic transmission in the central nervous system.

We have measured heat fluxes on the inner (cylindrical and edge) surfaces of a shock tube. The experiments were performed in gases (air, xenon) heated by a strong shock wave. For the first time, the heat flux in a shock wave was measured using sensors based on anisotropic single crystals of bismuth.

This article investigates the effects on the individual stages in the polymerization of C/sub 4/ olefins of using reactive aromatic hydrocarbons and high-aromatic cuts as components of catalysts. The effect of aromatic hydrocarbons on C/sub 4/ olefin polymerization is determined by the nature and concentration of the arene and also by the polymerization conditions. C/sub 4/ olefin polymerization in the presence of aromatic hydrocarbons results in a side reaction of alkylation of the aromatic hydrocarbons by the monomer to form a light alkylate (distilling up to 250/sup 0/C at 0.101 MPa). It is demonstrated that a lowering of the isobutene polymerization temperature suppresses the formation of light alkylate. Polybutene synthesized in the presence of aromatic hydrocarbons contains aromatic fragments as end-groups. Depending on the C/sub 4/ olefin polymerization conditions, the aromatic hydrocarbons can promote the formation of light alkylate, modify the catalyst and bind it strongly in the polymer product, and change the composition and properties of the polybutenes. It is concluded that the multiple role of aromatic compounds in cationic polymerization processes must be taken into account when they are used for the synthesis of low-molecular-weight polybutenes. Includes 3 tables.

A reaction which is the inverse of the synthesis of methanol was investigated on the surface of copper-containing catalysts. By using the data on the decomposition of methanol in accordance with the principle of a detailed equilibrium, information can be obtained on the nature and roles of the intermediate compounds which are formed during the synthesis of methanol. Apart from these reasons, the investigation of the dehydration of methanol is also important from the point of view of the study of the processes involved in its catalytic conversion (the preparation of CH/sub 2/O, hydrocarbons, H/sub 2/). Results indicated that the dehydration of methanol on copper-containing catalysts is realized sequentially with the formation of surface methoxyl, formaldehyde, and formate complexes. The formate type complex is broken down with the evolution of both CO and CO/sub 2/ into the gas phase. And, surface hydroxyl groups participate in the dehydration by reacting with the formaldehyde complex to form formate. A scheme for the synthesis of methanol is discussed in which a significant role is assigned to the surface OH groups which act as catalytically active centers. Carbon monoxide is activated by reacting with these centers to form formate structures which are then sequentiallymore » hydrated to methanol.« less

1. Carbon monoxide is a “probe” for the interaction of water with the surface of copper-containing catalysts. 2. The state of the surface of the catalyst affects the form of the water adsorbed onto copper applied to γ-Al2O3. Adsorption in the molecular form is more probable on the surface containing oxygen, and in the dissociative form on the reduced surface. 3. The surface of copper reduced to the metallic state can undergo partial oxidation from the effect of a mixture of CO and water vapor.

Excitatory miniature postsynaptic potentials were studied by an intracellular recording method in fast and slow muscle fibers ofLocusta migratorioides. Statistical analysis showed that liberation of mediator in both types of fibers can be predicted by the formula for a negative binomial distribution with a probability of 85%. This correlation is evidence of some degree of interaction between consecutive liberations of quanta of mediator by nerve endings. It is shown that the fraction of miniature potentials depending on the external calcium concentration is greater in fast muscle fibers. An increase in the magnesium ion concentration from 2 to 40 mM led to a decrease in the frequency of miniature potentials, and this decrease was greater in fast fibers; an increase in the magnesium ion concentration from 1 to 10 mM in calcium-free solutions, on the other hand, led to some increase in frequency, and this also was greater in fast muscle fibers. It is concluded that nerve endings in fast and slow muscle fibers differ in their sensitivity to changes in the ionic composition of the medium.

This article is aimed at studying the gas mixing conditions in the moving bed of a heat carrier as applied to the production of hydrogen. An increase in the gas velocity is shown to lead to an increase in the diffusion coefficient. When the sand bed height is increased from 0.15 to 0.45 m, the value of the diffusion coefficient is cut almost in half. The diffusion coefficient is independent of the solid-phase circulation velocity, which can be explained by the comparatively low velocity of descending movement of the solid particles in comparison with the velocity of gas filtration.

The formate ion is the most probable intermediate compound in the reaction for the conversion of CO and H2O, and the reaction of CO2 with H2, on reduced copper catalysts.

N-methyl-DL-aspartate induced in mice and rats hyperactivity and convulsions. In the mice convulsions effectively suppressed by selected antagonists of NMDA receptors AP 5 and AP 7, and also diazepam and ketamine. But hyperactivity very little attenuated by these substances in high doses. In the rats all these substances on the contrary suppressed hyperactivity and convulsions in the same degree. In the rats hynurenic acid prevented hyperactivity and convulsions. Observations point out to the fact that in mice there are two pharmacological and functional types of NMDA receptors whereas in rats there is only one type which is different from NMDA mice receptors.

These esters are produced as plasticizers. They include di-2-ethylhexyl phthalate (GOST JAil-Union State Standard] 8728-77), diisononyl phthalate (specification TU 6051356-70), and dibutyl phthalate (GOST 8728-77). It is necessary to improve their insulating properties in order to use these products as base stocks for dielectric liquids in capacitor insulation. We investigated the possibility of improving the dielectric indexes of dioctyl phthalate (DOP) by purification and addition of stabilizing additives.

Ignition ofPETN particles by a gas-detonation wave in a gas suspension has been studied experimentally. The critical pressure at which the total rate ofPETN decomposition increases sharply has been found using a method of multiwave pyrometry with variation in the pressure of the initial gas mixture from 0.1 to 0.4MPa. It is shown that this can occur owing to a large increase in thePETN surface area because of the fragmentation of melting particles in a high-enthalpy flow of gas.

A sample of used OMTI oil based on trixylenyl phosphate was used which did not meet specification requirements for optical density, acid number, content of xylenols and other property indexes. The filtered OMTI oil samples were finished by treatment with adsorbents and physiocochemical treatment with caustic solutions (aqueous and alcohol) were performed. Results of each treatment are presented. The effect of demulsifiers was investigated with the aim of intensifying the treatment and reducing the losses with the introduction of 0.5% Disolvan. The feasibility of reclaiming used turbine oils was demonstrated.