Showing papers by "Academy of Sciences of the Czech Republic published in 1982"
TL;DR: In this article, a linear response theory is applied to the Hall effect, thermopower and thermal conductivity in two-dimensional systems, and the periodic potential is taken into account.
Abstract: On the basis of linear response theory, the Hall conductivity is expressed as a sum of two contributions: one corresponding to the classical Drude-Zener formula, and a second which has no classical analogy. The developed theory is applied to the Hall effect, thermopower and thermal conductivity in two-dimensional systems. The periodic potential is taken into account.
444 citations
TL;DR: In this article, two types of amorphous and glassy Sb 2 S 3 were studied: a powder obtained by precipitating a SbCl 3 solution using a stream of hydrogen sulphide in a bath of boiling water and a glassy material in the form of thin platelets obtained by rotating cylinders.
Abstract: Two types of amorphous and glassy Sb 2 S 3 were studied: amorphous orange-red powder obtained by precipitating a SbCl 3 solution using a stream of hydrogen sulphide in a bath of boiling water and a glassy material in the form of thin platelets obtained by the method of rotating cylinders. It was found by DTA that there is a great difference in the crystallization entropy and temperature between the powder and glass. Radial electron density distribution curves were measured for both modifications and a difference analysis showed that they can be considered to be much the same. From the distribution curves it follows that the basic unit is a trigonal SbS 3 pyramid which forms in the case of Sb 2 S 3 glass, a covalent random network while for the amorphous powder a random ordering of crystalline-like and band-like (Sb 2 S 3 ) n molecules can be considered as an appropriate model. A comparison of radial electron density distribution curves for As 2 X ( X =S, Se, Te and Sb 2 S 3 shows that Sb 2 S 3 belongs to the class of glassy As 2 X 3 structures. A rule is found that in this class of glasses the mutual ratios of diameters of corresponding coordination spheres are constant. On the basis of coordination numbers and of broadening functions for individual coordination spheres it is shown that in the series As 2 S 3 :As 2 Se 3 As 2 Te 3 a gradual transition from a layer-like to a random network takes place and that glassy Sb 2 S 3 can be put beside As 2 Te 3 . This process is a result of the difference between orpiment-like configurations and the As 2 X 5 ones, which evoke chain branching and interconnecting. This leads finally for As 2 Te 3 and Sb 2 S 3 to a random continuous covalent network. This process is confirmed by increase of both occupation numbers and the widths of broadening functions corresponding to individual coordination spheres.
78 citations
TL;DR: In this paper, explicit expressions for NPP limiting current densities influenced by reactant adsorption are derived for two cases: (1) a linear NPP and (2) a lin
44 citations
TL;DR: The results suggest that the formation of the proteinase during growth may be controlled differently from that during sporulation.
Abstract: Bacillus megaterium 27 produces one exocellular metalloproteinase during growth as well as during sporogenesis. The formation of the enzyme during growth is repressed by the addition of amino acids of the leucine–isoleucine group. Its synthesis during sporogenesis is rather insensitive to repression. The enzyme is formed during the first 90 min after transfer to a sporulation medium, amino acids delaying only the onset of its synthesis as well as the onset of sporogenesis. The synthesis of the proteinase in asporogenic B. megaterium KM1 is repressed by amino acids during growth as well as during incubation in the sporulation medium and proceeds for a longer time under the latter condition. The results suggest that the formation of the proteinase during growth may be controlled differently from that during sporulation.
41 citations
Journal Article•
37 citations
TL;DR: In this article, a method for the separation of four isomers of lysergic acid α-hydroxyethlamide and its decomposition products ergine and erginine using LiC-hrosorb NH 2 as the stationary phase and isocratic elution is described.
36 citations
TL;DR: In this paper, a phenomenological theory of ferromagnetic resonances in a metallic cylinder magnetized along its axis is based on the simultaneous solution of the equation of motion and Maxwell's equations.
Abstract: A phenomenological theory of ferromagnetic resonances in a ferromagnetic metallic cylinder magnetized along its axis is based on the simultaneous solution of the equation of motion and Maxwell's equations. A general relaxation term in the equation of motion is used. The boundary conditions correspond to the dynamic surface anisotropy with the preferred direction parallel to the static magnetization. It is shown that the solution yields an infinite number of resonance modes of different spatial symmetry. Formulas for the surface impedance and the relative absorption of individual modes are derived. The effect of the finite radius of the cylinder on the resonance, antiresonance and spin wave resonance behaviour is discussed.
32 citations
TL;DR: In this paper, the spectral dependence of the index of refraction (n) in Ge40−xSbxS60 glasses has been described by a simple one-oscillator approximation using the Wemple-DiDomenico treatment (W-D).
Abstract: The spectral dependence of the index of refraction (n) in Ge40−xSbxS60 glasses has been described by a simple one-oscillator approximation using the Wemple-DiDomenico treatment (W-D). The possibility of application of the Moss formula or W-D in some amorphous materials for estimation of the optical gap (E
g) fromn or vice versa has been examined. From the results of optical and d.c. electrical conductivity measurements and bond statistics suggestions it can be concluded that many types of defect states are created in Ge40−xSbxS60 glasses, which pin the Fermi level in the vicinity ofE
g/2.
19 citations
TL;DR: Using experimentally determined curves representing the dependence of the amount of sorbed enzyme on the content of immobilized inhibitor, it is possible to estimate the order of magnitude of the equilibrium constant of the respective specific complex.
18 citations
17 citations
TL;DR: In this paper, the luminescence spectra, decay times, and EPR spectra of manganese activated aluminum nitride samples were studied under different conditions, according to the preparation conditions manganous can be present in AlN as Mn4+ or Mn2+ ions with orange or green emission band, respectively.
Abstract: The luminescence spectra, decay times, and EPR spectra of manganese activated aluminum nitride samples prepared under different conditions are studied. According to the preparation conditions manganese can be present in AlN as Mn4+ or Mn2+ ions with orange or green emission band, respectively. Efficient energy transfer from Mn2+ to Mn4+ ions takes place if both kinds of ions are present. At high concentration of manganese exceeding 0.005 wt% a new red emission band is observed, probably due to the pairs of interacting Mn4+ ions. The observed EPR spectra show HFS of Mn2+ ions and indicate that several nonequivalent positions of the Mn2+ ions with distorted cubic symmetry giving many possible values of the g-factor are present in AlN.
[Russian Text Ignored.]
TL;DR: The hypothesis of a presynaptic origin of PTP at this muscarinic synapse was corroborated in the experiments where acetylcholine stores were labelled with [3H] choline and the release of the label was increased during PTP.
TL;DR: Titanocene hydride derivatives induce cyclization of 1,2-divinylcyclohexanes to trans-and cis-1-methylene-octahydro-1H-indene and their isomerization to trans and cis-3-methyl-3a,4,5,6,7,7a-hexahydroid-1 hindene as mentioned in this paper.
TL;DR: Leozym, a commercial pectic enzyme preparation, was subjected to medium-pressure liquid chromatography on weakly, medium, and strongly acidic cation exchangers and weakly and strongly basic anion exchangers.
TL;DR: In this article, the relative Raman intensities associated with various electronic transitions are used simultaneously with the usually considered energy levels and g-values for determination of the phenomenological crystal field parameters in YbAG and YbGG.
Abstract: The relative Raman intensities associated with various electronic transitions are used simultaneously with the usually considered energy levels and g-values for determination of the phenomenological crystal-field parameters in YbAG and YbGG. The best-fit parameters reproduce well all the available data but their values do not agree with the superposition model of the crystal field. It is concluded that the earlier crystal-field calculation for Yb3+:YAG is impaired by the misinterpretation of the optical data.
[Russian Text Ignored].
TL;DR: In this article, the optimal electrolyte content in the active layer ensuring the maximum electrical characteristics of working electrodes has been found to depend on the structure and hydrophobic properties of the carbon catalyst.
TL;DR: The evaluation of electron‐diffraction patterns of both the primary septum and the adjacent circular zone of scar ring led to the conclusion that α‐chitin is present in both these parts of the mother bud scar.
Abstract: Crustacean and yeast cell wall chitin were analyzed by means of transmission electron microscopy and selected-area diffraction. Single fibrils 8–25 nm wide have been observed in the micrographs of crustacean chitin. Analysis of a series of diffraction patterns obtained from thin crustacean chitin platelets yielded results which were in a better agreement with the theoretical structural model than those measured earlier. In this respect electron diffraction is shown to be superior to the more commonly used x-ray diffraction. Yeast cell wall chitin had a less perfect structure than the crustacean chitin. Single fibrils were not observed on the micrographs and electron diffraction patterns did not show any preferred fiber orientation. The evaluation of electron-diffraction patterns of both the primary septum and the adjacent circular zone of scar ring led to the conclusion that α-chitin is present in both these parts of the mother bud scar.
TL;DR: In this article, a diatomics-in-molecules method was used to study the adaption of hydrogen atom on the surface of Li 9 clusters and the most obvious effects of the nonadiabatic behaviour of the system on the course of the adsorption process were considered.
TL;DR: In this paper, the spin-wave resonance modes in a metallic film are derived analytically for arbitrary values of the spinpinning parameter β in the case of parallel as well as perpendicular static magnetisation, under the assumption of weak interaction between the spin and the electromagnetic solution of the secular equation.
Abstract: The exchange-conductivity contribution to the linewidth of the spin-wave resonance modes in a metallic film is derived analytically for arbitrary values of the spin-pinning parameter β in the case of parallel as well as perpendicular static magnetisation, under the assumption of weak interaction between the spin- and the electromagnetic solution of the secular equation. Analytical results are compared with those obtained numerically for the full model. Very good agreement between the results of both models and a simple functional dependence of the analytical formulae on β gives a possibility to determine the surface anisotropy constant and other film parameters.
Der Leitfahigkeitsaustauschbeitrag zur Linienbreite der Spinwellenresonanzmoden in einem metallischen Film wird analytisch fur willkurliche Werte des Spinwellenfixierungsparameter β im Fall paralleler als auch senkrechter statischer Magnetisierung abgeleitet. Dabei wird eine schwache Wechselwirkung zwischen der Spin- und der elektromagnetischen Losung der Sakulargleichung angenommen. Die analytische Formel wird mit numerischen Ergebnissen der vollstandigen Theorie verglichen. Die sehr gute Ubereinstimmung zwischen den Ergebnissen und die einfache funktionale Abhangigkeit der analytischen Formel von β gibt eine Moglichkeit, den Wert der Oberflachenanisotropiekonstante sowie der anderen Filmparameter zu bestimmen.
TL;DR: In this article, the core structure of an edge dislocation in a liquid crystal is analyzed by using the Peierls-Nabarro method, and the stress necessary for a glide motion of dislocation and the dislocation core energy are estimated.
Abstract: The core structure of an edge dislocation in Sm A liquid crystal is analysed by using the Peierls-Nabarro method. The stress necessary for a glide motion of dislocation and the dislocation core energy are estimated.
TL;DR: In this article, the statistical properties for the couples of modes in Brillouin scattering are derived making use of the coherent state technique, assuming the initial fields to be coherent, and it is shown that periodical antibunching, bunching, and coherent state behaviour can occur, provided that the anti-Stokes interaction prevails.
Abstract: The statistical properties for the couples of modes in Brillouin scattering are derived making use of the coherent state technique. Assuming the initial fields to be coherent, it is shown that periodical antibunching, bunching as well as coherent state behaviour can occur, provided that the anti-Stokes interaction prevails. This is demonstrated with the help of the photocount distributions and their reduced factorial moments.
TL;DR: In this article, a method has been developed for the simultaneous measurement of several different transport coefficients on a sample, including electrical resistivity, thermal conductivity and thermopower, on a Bi single crystal at temperatures 1·5-50 K.
Abstract: A method has been developed for the simultaneous measurement of several different transport coefficients on a sample. Experiments were performed on a Bi single crystal at temperatures 1·5–50 K. Six transport properties were measured, including the electrical resistivity, thermal conductivity and thermopower. A set of quantities related to transport integrals of the phenomenological transport theory has been determined from experimental data. All the possible transport coefficients can be calculated from them. The possibilities of the determination from experiments of the full tensorial transport integrals for an anisotropic material like Bi are discussed.
TL;DR: In this paper, the authors derived a simple analytical expression for the real component of the microwave surface impedance in the ferromagnetic antiresonance region at the external field parallel to the sample surface.
Abstract: There is derived a simple analytical expression for the real component of the microwave surface impedance in the ferromagnetic antiresonance region at the external field parallel to the ferromagnetic metal sample surface. The formula for the field derivative of the surface impedance (the quantity usually measured in the experiment) is evaluated. Some properties of this expression are investigated and there are analyzed two definitions of the ferromagnetic antiresonance curve width which are suitable for the Landau-Lifshitz relaxation parameter determination from the experiment.
TL;DR: In this paper, the antisymmetric (A) and symmetric (S) SSWR modes in a conducting film are calculated in plane-wave approximation and in simple one-mode approximations.
Abstract: Intensities of antisymmetric (A) and symmetric (S) SSWR modes in a conducting film are calculated in plane-wave approximation and in simple one-mode approximations. Very good agreement between the two results is obtained for the integral intensities (i.e. resonance-line areas). Relations between the intensities of A and S modes detected experimentally in small films are interpreted taking into account thee field of surface charges occuring on film edges in A modes. Functional dependence of the A intensity on the spin-pinning parameterKs indicates that SSWR spectra should be observable even in films with very smallKs.
TL;DR: A new group of eudesmanolides -eudesman-6,12-olides was identified mainly on the basis of proton NMR spectroscopy and checked by X-ray analysis.
TL;DR: In this paper, the electronic bandstructures of fcc rhodium have been calculated for the normal value of the lattice constant and one 5% smaller, using the nonrelativistic symmetrized augmented plane wave method.
Abstract: The electronic bandstructures of fcc rhodium have been calculated for the normal value of the lattice constant and one 5% smaller, using the nonrelativistic symmetrized augmented plane wave method. The results of the first calculation are in good agreement with those of other workers. Under pressure the d-bands shift and broaden appreciably, resulting in a slight increase in d-occupation.
TL;DR: In this article, optical and photo-electrical studies performed on the layers of a-Si:H and a- Si:H implanted by C1 or As ions allowed the authors to draw an indirect conclusion about the stabilization of the Si-H bond that manifests itself in decreasing the Staebler-Wronski effect and in an increase of the exodiffusion temperature of hydrogen.
Abstract: Optical and photoelectrical studies performed on the layers of a-Si:H and a-Si:H implanted by C1 or As ions allowed us to draw an indirect conclusion /1/ about the stabilization of the Si-H bond that manifests itself in decreasing the Staebler-Wronski effect /2/ and in an increase of the exodiffusion temperature of hydrogen. One of the most direct methods for the determination of the bond stability is the IR absorption spectroscopy in the range of frequenciescorresponding to the vibrations of the Si-H bond in various configurations.
TL;DR: In this article, the theory of the intraatomic CVV Auger spectrum for a single impurity in a perfect crystal with an initially filled band is formulated within the generalized Wolff-Clogston model.
Abstract: The theory of the intraatomic CVV Auger spectrum for a single impurity in a perfect crystal with an initially filled band is formulated within the generalized Wolff-Clogston model. The impurity is characterized by its atomic level, the impurity-bulk coupling, and the contact pair interaction of electrons. The exact solution to the problem is obtained, and the theory is numerically illustrated for a simple bandstructure model.