Showing papers by "Armenian National Academy of Sciences published in 1986"
TL;DR: In this paper, the zero-field splitting and g-values of the 3A2 ground state for d8 impurity ions in a trigonally distorted octahedral field are calculated.
Abstract: On the basis of the crystal-field theory the zero-field splitting and g-values of the 3A2 ground state for d8 impurity ions in a trigonally distorted octahedral field are calculated. Using perturbation theory the analytical expressions connecting the spin-Hamiltonian parameters with the crystal-field parameters are obtained. It is shown that experimental data for Cu3+ in Al2O3, and Ni2+ in Al2O3, α-LiIO3, LiNbO3 can be explained taking into account the influence of all the excited levels on the ground state.
[Russian Text Ignored].
44 citations
TL;DR: The set of all translation invariant Gibbs states in theq-state Potts model for the case ofq large enough and the other parameters to be arbitrary is described.
Abstract: We describe the set of all translation invariant Gibbs states in theq-state Potts model for the case ofq large enough and the other parameters to be arbitrary.
39 citations
TL;DR: In this paper, the authors considered the problem of channelled ultrarelativistic positron radiation in the longitudinal standing hypersonic (HS) wave field and obtained analytical expressions for the first harmonic radiation intensity and for the upper limit of the radiation frequency depending on the HS wave parameters.
32 citations
TL;DR: In this article, the influence of thermal expansion and thermal expansion on the spin-phonon interactions in α-LiIO3, single crystal lattice is investigated. And the deformation of the oxygen octahedron close to the Cr3+ ion is determined.
Abstract: Results concerning the influence of hydrostatic pressure, uniaxial stress, and temperature on the spin-Hamiltonian parameters of Cr3+ in α-LiIO3, single crystals are reported. Assuming that the local compressibility and thermal expansion of the nearest surroundings of the Cr3+ ion is the same as of α-LiIO3 crystal lattice it is shown that the temperature and pressure variations on the D-parameter are mainly due to thermal expansion and compressibility of the lattice, whereas the contribution from spin-phonon interactions is several times smaller. The deformation of the oxygen octahedron close to the Cr3+ ion is determined.
18 citations
TL;DR: In this paper, single crystals of yttrium aluminium garnet doped with zirconium ions are grown from the melt and their optical and ESR absorption spectra are investigated, and it is established that the color centers and paramagnetic centers have an identical nature being caused by Zr3+ ions in dodechahedrical sites of the garnet lattice.
Abstract: Single crystals of yttrium aluminium garnet doped with zirconium ions (Y3Al5O12:Zr, YAG:Zr) are grown from the melt and their optical and ESR absorption spectra are investigated. It is established that the color centers and paramagnetic centers have an identical nature being caused by Zr3+ ions in dodechahedrical sites of the garnet lattice. The experimental results are interpreted in the approximation of crystal field and molecular orbital theories.
[Russian Text Ignored].
12 citations
TL;DR: The apoform of neurocuprein, the copper protein from brain and chromaffin granules, was found to be a potent inhibitor of the hydroxylating activity of dopamine beta-monooxygenase, whereas the holoform has no effect on the activity of the enzyme.
11 citations
TL;DR: In this article, the authors considered the possibility of determining the refractive index profiles of optical planar waveguides, formed by ion implantation in YAG:Nd 3+ crystals, by measuring the mode spectrum of the waveguide.
11 citations
TL;DR: The results suggest that decenoic acid-induced changes in membrane fluidity modulate cholinoreceptive properties of the neuronal membrane by the inhibition of the K+ carrier involved in the generation of ACh responses.
Abstract: 1.
We have examined the effects of short-chain fatty acids on acetylcholine (ACh)-induced transmembrane currents using internally dialized neurons ofHelix.
2.
Decenoic acid, which increased the fluidity of excitable membranes, caused dramatic changes in the voltage sensitivity of ACh currents consisting of an ACh-induced increase in membrane permeability for K+ and Na+ ions and a shift of theErev of these ACh responses to more positive potentials. Valeric acid, which did not change the membrane fluidity, had no effect on this type of ACh response.
3.
Changes of theENa andECl had no effect on the size of the decenoic acid-induced shift of theErev. But the influence of decenoic acid on the voltage sensitivity of ACh-induced currents almost disappeared after the change of theEK by the reduction of the internal K concentration.
4.
Decenoic acid had no effect on ACh responses in which K+ ions were not involved in the generation of ACh-induced currents.
5.
The results suggest that decenoic acid-induced changes in membrane fluidity modulate cholinoreceptive properties of the neuronal membrane by the inhibition of the K+ carrier involved in the generation of ACh responses.
11 citations
TL;DR: From data of both X-ray phase analysis and differential thermal analysis, as well as measurements of the crystal lattice parameters, electric conductivity and diffusion coefficients of cations in ceramics and single crystals, the width of the homogeneity region of the lead molybdate phase which lies in the composition range of 49.85-50.50 mole% MoO3, has been determined.
Abstract: From data of both X-ray phase analysis and differential thermal analysis, as well from measurements of the crystal lattice parameters, electric conductivity and diffusion coefficients of cations in ceramics and single crystals the width of the homogeneity region of the lead molybdate phase which lies in the composition range of 49.85–50.50 mole% MoO3, has been determined. It was also established that the compound was a daltonide phase. The results obtained explain the Pb/Mo ratio changes along the crystal.
[Russian Text Ignored.]
9 citations
TL;DR: 2-Decenoic acid (DA), having 10 carbon atoms in the hydrocarbon chain, suppressed the excitability of bursting neurons RPal (Sakharov and Salanki, 1969), while valeric acid (VA), having 5 carbon atoms, had no significant effect on excitability.
Abstract: 1.
The effects of short-chain fatty acids on the membrane excitability, currentvoltage (I-V) characteristics, and cell volume ofHelix pomatia neurons were studied.
2.
2-Decenoic acid (DA), having 10 carbon atoms in the hydrocarbon chain, suppressed the excitability of bursting neurons RPal (Sakharov and Salanki, 1969) for 30–60 min, while valeric acid (VA), having 5 carbon atoms, had no significant effect on excitability.
3.
DA had three different effects on the excitability of beating neurons: in some neurons DA suppressed excitability as in bursting neurons; in a second type of neuron DA had a negligible effect on excitability; and in the neuron located near RPa1 DA had a pentylentetrazol (PTZ)-like effect, i.e., it converted the discharge of the neuron from beating to bursting.
4.
DA decreased the peak value of the current, inducing a negative-resistance region in theI-V curve of the bursting neuron without any change in the level of the voltage at which the current reaches its maximal value.
5.
DA inhibited the hyperpolarization induced by activation of the Na+ pump, tested after preliminary enrichment of neurons with Na+ ions by incubation in a potassium-free solution for 20 min.
6.
DA caused a swelling of the neuron by about 10% which was independent of the Na+ pump. In all the above-mentioned cases VA had no significant effect.
8 citations
TL;DR: In this article, a three-prism method for measuring losses of optical waveguides is presented, which can be applied to all kinds of planar waveguide and enables one to obtain results which are independent of the coupling efficiencies of the middle movable prism and laser radiation fluctuations.
TL;DR: All the fatty acids used had an inhibiting effect on the ouabain-insensitive22Na efflux from the cells independent on the number of carbon atoms in the hydrocarbon chain.
Abstract: 1.
The effect of short-chain fatty acids on both ouabain-sensitive and ouabaininsensitive fractions of22Na efflux from the neurons ofHelix pomatia was studied.
2.
Fatty acids, having fewer than 10 carbon atoms in the hydrocarbon chain, increased the ouabain-sensitive22Na efflux from the neurons, while fatty acids, having more than 9 carbon atoms, inhibited the22Na efflux in comparison with that in normal physiological solution.
3.
All the fatty acids used had an inhibiting effect on the ouabain-insensitive22Na efflux from the cells independent on the number of carbon atoms in the hydrocarbon chain.
4.
These studies indicate that these short-chain fatty acids can be effective modulators of both ouabain-sensitive and ouabain-insensitive fractions of Na efflux from the cells.
TL;DR: In this paper, the results of experimental and theoretical investigations of the absorption of the pumping lamp radiation from the excited (4 I 13 2 ) level of erbium ions in LuAG are presented.
TL;DR: Application of phospholipase C to isolated voltage‐clamped molluscan neurons substantially increased the voltage‐gated Ca current (I ca) in most of the cells studied and inhibited I ca in all neurons.
TL;DR: In this article, colour centers in YAlO3:Pr3+ crystals originating under xenon lamp or y-radiation and oxidizing annealing are considered and the nature of colour centers under these treatments is similar in nominally pure and Pr3+ containing crystals but the intensity of induced absorption lines is higher in activated crystals which assumably is associated with valent transitions of Pr ions.
Abstract: Colour centers in YAlO3:Pr3+ crystals originating under xenon lamp or y–radiation and oxidizing annealing are considered. The nature of colour centers under these treatments is similar in nominally pure and Pr3+ containing crystals but the intensity of induced absorption lines is higher in activated crystals which assumably is associated with valent transitions of Pr ions.
[Russian text Ignored]
TL;DR: In this article, the authors describe the spherical X-ray diffractional focusing discovered outside the crystal affected by a temperature gradient and show that the focus distance decreases with the growth of the temperature gradient if the latter is anti-parallel to the diffraction vector.
TL;DR: A fraction enriched in dendro-dendritic synaptosomes was isolated from rat olfactory bulb by a rapid method and evoked a considerable release of GABA and dopamine but not of noradrenaline or serotonin in accordance with histochemical published data.
Abstract: A fraction enriched in dendro-dendritic synaptosomes was isolated from rat olfactory bulb by a rapid method. Synaptosomes preserved their ultrastructure and showed configurational changes in relation to incubation in physiological ion medium as described earlier in the case of cortical synaptosomes. Dendro-dendritic synaptosomes were larger and contained more mitochondria than cortical synaptosomes. Doublets of terminals synapsing with each other were frequently seen and each terminal contained synaptic vesicles. Oxygen consumption of dendro-dendritic synaptosomes was decreased by ouabain and increased by 2,4-dinitrophenol. High-potassium medium evoked a considerable release of GABA and dopamine but not of noradrenaline or serotonin in accordance with histochemical published data.
TL;DR: The blood of 57 donors was used in the work; the data obtained were subjected to statistical treatment using the Student--Fischer criterion.
Abstract: In experiments studying platelet aggregation we used platelet-rich plasma (PRP). The blood of healthy donors (who had not taken nonsteroid antiinflammatory drugs for a period of two weeks) was collected in a polyethylene vessel with a 3.8% solution of sodium citrate (9:1 by volume) and centrifuged for i0 min at 210g. The upper layer was collected and, after measuring the number of platelets in an aliquot with the aid of a Picoscale microparticle counter (Hungary), their number was adjusted to 0.25,10 i -0.30,106 per ul with the aid of buffer solution (0.14 M NaCI, I0 mM Tris-HC1, pH 7.4). The degree of platelet aggregation, expressed in percent of light transmission, was recorded by the Born method [3] using a two-channel aggregometer from Chrono-Log Corp., Haverton, PA (USA), connected to an automatic recording device. Portions of 5 ul of i mM aqueous solutions (or solutions in dimethyl sulfoxide) of the test substances were added to 450 ul of PRP and incubated at 37~ for i0 min, after which an inducer of platelet aggregation was introduced. Aggregation was induced by adding 50 ~i of aqueous solutions of ADP, collagen, adrenalin (Dade), or an ethanol solution of arachidonic acid (Sigma); the final concentrations of the solutions were 2.i0 -s M, 2.10 -~ mg/ml, 10 -5 M, and 3.3.10-7M, respectively. The blood of 57 donors was used in the work; the data obtained were subjected to statistical treatment using the Student--Fischer criterion.
TL;DR: In this article, a selfconsistent set of equations for ultrashort pulse propagation through the resonance two-level atomic medium is solved, where phase modulation and group velocity dependence on both intensity and frequency are taken into account.
TL;DR: In this article, the corrosion and erosion by heat and electricity of refractories used as thermal insulation in glass-melting electric furnaces is analyzed and a method for their protection involving the installation of molybdenum sheeting is described.
Abstract: This paper analyzes the corrosion and erosion by heat and electricity of refractories used as thermal insulation in glass-melting electric furnaces and describes a method for their protection involving the installation of molybdenum sheeting between the electrodes and the refractories. The analysis of this protective system incorporates all the process parameters occurring in the furnace, including the electrical and thermal and corrosive behavior of the glass undergoing melting, and enables recommendations to be made for optimal disposition and utilization of the insulating and protecting materials.
TL;DR: 74. M. Thibonnier, M. D, Lardoux, and P. Corvol, Br.
Abstract: 74. M. Thibonnier, M. D, Lardoux, and P. Corvol, Br. J. Clin Pharmacol., 9, 561-567 (1980). 75. K. Tomioka, T. Yamada, and T. Takenaka, Arch. Int. Pharmacodyn., 256, 97-107 (1982). 76. Y. Uchida, M. Nakamura, S. Shimizu, et al., Arc!~. Int. Pharmacodyn., 262, 132-139 (]983). 77. E. M. Vaughan Williams, J. S. Hillar, and T. J. Campbell, Cardiovasc. Res., 16, 233-239 (1982). 78. A. J. M. Verberne and M. J. Rand, Eur. J. Pharmacol., ~i08, 193-196 (1985). 79. H. J. Waal-Manning and F. O. Simpson, Br. J. Clin. Pharmacol., 13, No. i, Suppl. 65S-73S (1982). 80. J. J. Walker, I. A. Greer, M. McLaren, et al., Br. J. Obstet. Gynaec., 90, 1094-1098 (1983). 81. J. K. Woodward and H. C. Cheng, J. Pharm. Pharmacol., 34, 193-195 (1982). 82. H. Zschedrich, W. Neuroh, J. Lutt, et al., Klin. Wochenschr., 61, 661-667 (1983).
TL;DR: The fate of concepts which comprise the philosophical knowledge of our epoch, an epoch in which the information explosion, including scientific information, has become a universal conditioning factor, unfolds in various ways as mentioned in this paper.
Abstract: The fate of concepts which comprise the philosophical knowledge of our epoch, an epoch in which the information explosion, including scientific information, has become a universal conditioning factor, unfolds in various ways. Some of these concepts are inscribed in a basic way in the categorial apparatus of philosophy. Others, having failed the tests of time and philosophical and methodological practice, lose their significance for philosophy and drop out of the conceptual apparatus as easily as they entered. Among the various new concepts in contemporary philosophy, that of "metaphilosophy" occupies a special place.
01 Jan 1986
TL;DR: In this article, a light-induced Frederiks transition is predicted for cells with a hybrid nematic orientation, in which radiation absorption may reorient the director, and conditions are found for critical behavior to occur for a non-threshold interaction.
Abstract: The orientation interaction is considered for light waves and liquid crystals with a uniform initial director orientation (such crystals include twisted nematics and cholesterics, and crystals with “hybrid” or “hyperhybrid” structures). Conditions are found for critical behavior to occur for a nonthreshold interaction. A light-induced Frederiks transition is predicted for cells with a hybrid nematic orientation, in which radiation absorption may reorient the director.
TL;DR: A non‐blue copper‐containing glycoprotein was isolated from Pseudomonas aeruginosa and may be considered as an endogenous inhibitor of nitrite reductase.
TL;DR: In this paper, a systematical study of electrical conductivity and EPR of iodine-doped anthracene polymers (C14H6Ix)n is carried out within a wide range of iodine concentrations (0.07 ≦ x ≦ 0.85).
Abstract: A systematical study of electrical conductivity and EPR of iodine-doped anthracene polymers (C14H6Ix)n is carried out within a wide range of iodine concentrations (0.07 ≦ x ≦ 0.85). The room temperature electrical conductivity has a broad maximum near x = 0.5. No metallic-type conduction is observed. The intensity of EPR signal for all of the investigated samples depends on temperature according to the Curie law and has a minimum near x = 0.19. A clear decoupling of paramagnetism with iodine concentration and electrical conductivity is detected. An idealized model of the structure of (C14H6Ix)n including polarons and bipolarons is proposed. On the base of the model a mechanism of generation and compensation of spin and charge during the doping process is discussed and an interpretation of experimental data is given.
[Russian Text Ignored]
TL;DR: The applications of methods of integral transforms and Vinner-Hopf to solution of problems of dynamical elasticity are given in this article, where the authors consider the problem of finding the optimal solution of a dynamic elasticity problem.
TL;DR: In this article, a general method of formulation and crystal growth of ornamental material with color smoothly changing from violet to red is proposed. But the method is not suitable for the use of crystal fields.
Abstract: “Compositional” shift of spectral lines of Eu2+, Yb2+ and Zr3+ ions resulting from crystal field variation in e-sites of the garnet lattice is considered with respect to the provision of a general method of formulation and crystal growth of ornamental material with colour smoothly changing from violet to red.
[Russian Text Ignored]