Showing papers by "Academy of Sciences of the Czech Republic published in 1985"
TL;DR: Le complexe de transfert de charge organique, β-(BEDT-TTF) 2 I 3 avec BEDT TTF: bis(ethylenedithio) tetrathiafulvalene est le 1er supraconducteur organique as discussed by the authors, a base de soufre, sous pression ambiante.
Abstract: Le complexe de transfert de charge organique, β-(BEDT-TTF) 2 I 3 avec BEDT-TTF: bis(ethylenedithio) tetrathiafulvalene est le 1er supraconducteur organique, a base de soufre, sous pression ambiante. Donnees sur sa structure cristalline
87 citations
TL;DR: In this paper, a new experimental method for the evaluation of minimum fluidizing velocity in gas fluidized beds is proposed based on the pressure fluctuations measurements, which is determined solely from the measurements in the fluidized bed regime, unlike the traditional method where experiments in the fixed bed regime are also necessary.
Abstract: A new experimental method for the evaluation of minimum fluidizing velocity in gas fluidized beds is proposed based on the pressure fluctuations measurements. The minimum fluidizing velocity is determined solely from the measurements in the fluidized bed regime, unlike the traditional method, where experiments in the fixed bed regime are also necessary. Using the proposed method the on-line evaluation and prediction of the minimum fluidizing velocity is possible which is important for the control of industrial fluidized bed reactors.
76 citations
TL;DR: In this article, the swelling and mechanical behavior of copolymer of diethylacrylamide (DEAAm) with a small quantity of sodium methacrylate (mole fraction xMNa = 0.067) swollen in water was investigated in the temperature range 1 − 80°C.
45 citations
TL;DR: A comparison of the results obtained by solving the Boltzmann equation with the experimental results from optical emissions obtained in SF6-O2 radiofrequency discharges, when N2, Ar, and He are also admitted as actinometers, has allowed to explore the potentialities and limits of actinometry.
Abstract: A comparison of the results obtained by solving the Boltzmann equation with the experimental results from optical emissions obtained in SF6-O2 radiofrequency discharges, when N2, Ar, and He are also admitted as actinometers, has allowed us to explore the potentialities and limits of actinometry. The use of different actinometers also allowed us to monitor the evolution of the electron distribution functions as a function of the plasma parameters.
42 citations
TL;DR: In this article, the standard Kubo formulas for the thermal transport coefficients are profoundly altered in the presence of a quantizing magnetic field and quite general expressions are derived using quantum linear-response theory.
Abstract: The standard Kubo formulas (current-current correlation functions) for the thermal transport coefficients are profoundly altered in the presence of a quantizing magnetic field. Quite general expressions are derived using quantum linear-response theory. They clearly reflect the role of magnetization in the electronic thermal transport. These fundamental corrections are of purely quantum-mechanical origin and vanish in the classical high-field limit.
40 citations
TL;DR: Two types of sporogony of the microsporidian Chytridiopsis typographi in the midgut of adult bark beetle, Ips typographus, have been examined by means of light and electron microscopy and new data is reported on spore dimorphism and on the formation of pansporoblasts in two types of spore types.
23 citations
TL;DR: In this article, the usual correspondence between twistors and geometrical objects in the Minkowski space is generalized to the supertwistor case by means of flag supermanifolds.
Abstract: In the paper the usual correspondence between twistors and geometrical objects in the Minkowski space is generalized to the supertwistor case by means of flag supermanifolds. This supertwistor correspondence is treated in detail. Chiral and non-chiral superspaces are constructed and their properties studied by means of supertwistors.
20 citations
TL;DR: In this article, the authors investigated the gas phase protonation of β-amino alcohols and subsequent water loss in an ion cyclotron resonance spectrometer and found that the loss of water is correlated with the formation of oxonium ions.
Abstract: The gas phase protonation of β-amino alcohols and subsequent water loss is investigated in an ion cyclotron resonance spectrometer. It is found that the loss of water is correlated with the formation of oxonium ions (OH protonation). A relationship is found between the extent of internal stabilization at short interfunctional distance in protonated amono alcohols and the exoergicity of protonation required to induce the loss of a water molecule.
16 citations
TL;DR: In the development of the microsporidian Vairimorpha ephestiae are two types of sporogony: one ending with single binucleate spores, and a second with spores in octosporous pansporoblasts, both of which are uninucleate.
13 citations
TL;DR: In this paper, an energy transfer between Ce3+ and Nd3+ ions in YAlG:Nd,Ce laser crystal with varying small Ce concentrations has been studied.
Abstract: Laser excited luminescence has been used to study an energy transfer between Ce3+ and Nd3+ ions in YAlG:Nd,Ce laser crystal with varying small Ce concentrations. Radiative Ce3+→Nd3+ energy transfer dominates in the studied single crystal samples but this process can also be accompanied by multistep transfer mechanisms (for example by (Ce3+→Ce3+)n→ Nd3+ transfer mechanism). The Ce3+→Nd3+ radiative energy transfer improves pumping of green and yellow excitation lines in YAlG:Nd,Ce laser rods because the contribution of the additional transfer pumping of Nd3+ ions from Ce3+ ions is more than three times greater than should be expected from concentration differences between Nd and Ce. This favourable behaviour is explained from high quantum efficiency of Ce3+ emission and higher Ce3+ absorption cross sections in comparison with the Nd3+ ones (more than one order of magnitude difference).
12 citations
TL;DR: The chemical stability of anion radical TCNQ- salts derived from low-molecular weight and polymer 1,3-disubstituted imidazoles and poly(trimethylammonium ethyl methacrylate) was investigated spectrophotometrically in dimethylformamide as a function of time, water content and the presence of oxygen.
Abstract: The chemical stability of anion radical TCNQ- salts derived from low-molecular weight and polymer 1,3-disubstituted imidazoles and poly(trimethylammonium ethyl methacrylate) was investigated spectrophotometrically in dimethylformamide as a function of time, water content and the presence of oxygen The low-molecular weight TCNQ- salts are stable in anhydrous DMF also in the presence of oxygen Polymer salts are decomposed already in anhydrous DMF in an ihert atmosphere The decomposition products are the known α,α-dicyano-p-toluoyl-cyanide and the still unidentified compound with an intensive absorption at 330 nm Along with protolytic reactions, direct oxidation with oxygen also participates in the decomposition of TCNQ- in aqueous DMF in the presence of oxygen
Die chemische Stabilitat der mit niedermolekularen und polymeren 1,3-disubstituierten Imidazolen sowie mit Poly(trimethylammonium-ethylmethacrylat) gebildeten Salze des Anionenradikals TCNQ- wurde spektralphotometrisch in Dimethylformamid in Abhangigkeit von der Zeit und vom Wassergehalt sowie in An- und Abwesenheit von Sauerstoff untersucht Die niedermolekularen TCNQ--Salze sind in wasserfreiem DMF auch in Gegenwart von Sauerstoff stabil Die polymeren Salze werden bereits in wasserfreiem DMF in einer inerten Atmosphare zersetzt Als Zersetzungsprodukte treten das bekannte α,α-Dicyano-p-toluoyl-cyanid und eine noch nicht identifizierte Verbindung mit einer intensiven Absorption bei 330 nm auf Neben protolytischen Reaktionen spielt auch die direkte Oxidation durch Sauerstoff bei der Zersetzung von TCNQ- in wasrigem DMF eine Rolle
TL;DR: In this paper, optical absorption, conductivity and thermopower measurements were performed on glasses of the pseudobinary (GeS 2 ) x (Bi 2 S 3 ) 1−x system.
Abstract: Measurements of optical absorption, conductivity and thermopower were performed on glasses of the pseudobinary (GeS 2 ) x (Bi 2 S 3 ) 1−x system. The results are interpreted on the assumption that the glasses are inhomogeneous on a medium scale range. Evidence for this comes from DSC, XRD and IR reflectivity measurements. The compositional dependence of the conductivity can be well described by percolation-controlled transport. A p → n transition occurs in the vicinity of a percolation threshold.
TL;DR: The behavior of the initial permeability of the single crystal magnetite and of the Mn0·5Fe2·5O4 ferrite (Mn-ferrite) is studied by two methods in the 10 to 300 K temperature range at three audio frequencies as mentioned in this paper.
Abstract: The behaviour of the initial permeabilityμ of the single crystal magnetite and of the Mn0·5Fe2·5O4 ferrite (Mn-ferrite) is studied by two methods in the 10 to 300 K temperature range at three audio frequencies. Two anomalies in the temperature dependence ofμ were found in magnetite. The first, occurring near the Verwey transition,Tv=121 K, appeared to be independent of the measuring frequency. The other, near 40 K, was found to be frequency dependent and confirmed thus the presence of an electronic type of the relaxation process.
TL;DR: In this article, the electronic structure of a semi-infinite crystal with a partial coverage by adatoms is studied within the tight-binding formalism, and the effect of surface disorder is treated within the coherent potential approximation.
Abstract: The electronic structure of a semiinfinite crystal with a partial coverage by adatoms is studied within the tight-binding formalism. The effect of the surface is described via the surface Green function method, and the effect of disorder is treated within the coherent potential approximation. The local state densities at/near the surface and the interaction energy of adatoms are calculated as functions of the coverage. The examples representing the case of a gas adsorption on the transition metal surfaces, as well as the adsorption of the transition metal atoms on the transition metal surfaces are investigated numerically.
TL;DR: In this paper, the authors investigated the geometry and stability of such a disclination system in a high electric field and the critical electric field causing the disclination annihilation is estimated, and proposed a mutual disclination annihilation mechanism for the field induced transition from helicoidal Sm C* structure to unwound Sm C * structure with the twist along the sample thickness.
Abstract: In thick samples of Sm C* liquid crystals the helicoidal structure in the sample centre is connected to the unwound structure near sample surfaces by a regular system of (−2π) and (+2π)-twist disclinations associated in rows near the upper and lower sample surfaces The geometry and stability of such a disclination system in a high electric field is investigated and the critical electric field causing the disclination annihilation is estimated The mutual disclination annihilation is the proposed mechanism for the field induced transition from helicoidal Sm C* structure to unwound Sm C* structure with the twist along the sample thickness
TL;DR: The composition of fatty acids in high-production mutants differed substantially from that of the parent strains, so fatty acid analysis is probably only applicable in the taxonomy of non-mutated isolates of Claviceps cultured under standard conditions.
Abstract: Fatty acids were identified in the submerged mycelium of Claviceps purpurea, Claviceps paspali, Claviceps fusiformis and Claviceps sp. SD-58 by gas chromatography-mass spectrometry (GC-MS) and used for a chemotaxonomical study. A close relatedness was found between Claviceps sp. SD-58 and C. fusiformis. The composition of fatty acids in high-production mutants differed substantially from that of the parent strains. Fatty acid analysis is thus probably only applicable in the taxonomy of non-mutated isolates of Claviceps cultured under standard conditions.
TL;DR: In this paper, the elastic stresses due to the accommodation of elastic or plastic deformations differing in the both component crystals are calculated, and the elastic strength of the bicrystal composed of two anisotropic half-spaces joined by a planar infinite boundary is calculated.
Abstract: The bicrystal composed of two anisotropic half-spaces joined by a planar infinite boundary is uniaxially deformed in tension or compression. The additional elastic stresses due to the accommodation of elastic or plastic deformations differing in the both component crystals are calculated.
01 Jan 1985
TL;DR: Modern developments in nondifferentiable analysis have now made it possible to handle nondifferentiability optimal control problems, which in the most general case may involve compositions of non-differentiable functionals and operators.
Abstract: Modern developments in nondifferentiable analysis have now made it possible to handle nondifferentiable optimal control problems. Maximum principles of considerable generality have been derived by Clarke (1976), and a number of effective numerical methods for minimizing nonsmooth objectives are available. Nevertheless, nondifferentiable optimal control problems are still difficult to solve. The reason lies in their structure, which in the most general case may involve compositions of non-differentiable functionals and operators.
TL;DR: A novel method of serine determination during Edman degradation of proteins and peptides which is based on the reaction ofSerine degradation products with alkyl thiols is described and permits the products ofserine degradation to be obtained in a 70-80% yield.
TL;DR: In this article, the elastic interaction between dispiration and the 2π-disclination in Sm C* phases of liquid crystal is estimated and the core energy of the twist-edge dispiration with the Burgers vector equal to the smectic layer thickness is estimated using the Peierls-Nabarro model.
Abstract: The elastic interaction between the dispiration and the 2π-disclination in Sm C* phases of liquid crystal is estimated. It is shown that this interaction can influence the mobility of the 2π-disclinations through the Sm C* structure. The core energy of the twist-edge dispiration with the Burgers vector equal to the smectic layer thickness is estimated using the Peierls-Nabarro model.
TL;DR: The quadratic-APW (QAPW) method as mentioned in this paper is a more general formulation of the linear APW (LAPW), where the exact radial solution inside the muffin-tin (MT) sphere is replaced by its Taylor expansion with respect to the energy.
Abstract: Recently linearized versions of the augmented plane wave (APW) method have been introduced. The quadratic-APW (QAPW) method is presented which is a more general formulation of the linear-APW (LAPW) methods. Here the exact radial solution inside the muffin-tin (MT) sphere is replaced by its Taylor expansion with respect to the energy, truncated after the quadratic term, i.e. with higher accuracy when compared with the standard LAPW method which uses only the linear term. The standard LAPW method is obtained as a special case from our formulation. Similarly to the standard LAPW method, the energy independent APW's are formed from approximate radial wave functions which lead to the secular equations linear in energy. The analysis of the solution inside the MT-sphere shows that the eigenvalue error is proportional to (E-E0)6 in the method suggested as compared with (E-E0)4 for the standard LAPW method. As an application both non-self-consistent and self-consistent calculations are presented for the band structure of FCC copper metal.
TL;DR: In this paper, the authors examined the kinetics of iodine laser amplifiers by solving the time evolution equations of chemical kinetics during optical pumping and found that there exists an optimum pulse strength beyond which the inversion in the laser mixture no longer grows appreciably, only its lifetime is shortened.
Abstract: The kinetics of iodine laser amplifiers is examined by solving the time evolution equations of chemical kinetics during optical pumping. The pumping radiation intensity is modelled by a black body of the temperature varying in time (corresponding to the flash lamp pulse). A brief comparison is made of pumping effects by long and short light pulses. Pumping by the long pulse is studied in more detail and it is found that there exists an optimum pulse strength beyond which the inversion in the laser mixture no longer grows appreciably, only its lifetime is shortened. In this connection the effect of pyrolysis of the alkyliodide molecule is also discussed. The pyrolysis is found to occur under very strong illumination, but it does not interfere with the photolytic decomposition and the optimum laser action. Finally, the influence of the reaction rate constants is studied in a systematic way and only few of them are found to carry real weight.
TL;DR: The presence of a very fragrant component, C12H20O, in the liverwort Lophocolea heterophylla was proven in this paper, and a possible method for the isolation of this still unknown substance is discussed.
Abstract: The presence of a very fragrant component, C12H20O, in the liverwort Lophocolea heterophylla was proven. A possible method for the isolation of this still unknown substance is discussed. The special ‚mossy’ note of this natural product should be interesting as a possible component of fragrancies.
01 Jan 1985
TL;DR: In this paper, an itinerant LCAO model was proposed to predict the electronic structure of semimagnetic (Cd, Mn) Te using photoemission data from the (110) face of CdTe and Cd0.5Mn 0.5Te.
Abstract: The electronic structure of semimagnetic (Cd, Mn) Te involves the Mn3d states which strongly affect disorder, localized correlations, and hybridization. The model introduced here is LCAO, itinerant and incorporates both chemical disorder and magnetic moment fluctuations. Its predictions, obtained using the CPA, are compared with extensive photoemission data from the (110) face of CdTe and Cd0.5Mn0.5Te samples, measured using synchrotron light at the BESSY facility. For the first time, we identify in UPS the Mn3d states. Most of the other observed features are also classified as bulk alloy electronic structure properties.
TL;DR: In this article, the distortion of X-ray spectrum measured by the method of vertical dispersion is estimated and the function and adjustment of the spectrometer is discussed, and the formula for diffracted power for any Xray beam which may be diffracted from two crystals in antiparallel position is derived.
Abstract: The formula for diffracted power for any X-ray beam which may be diffracted from two crystals in antiparallel position is derived. The distortion of X-ray spectrum measured by the method of vertical dispersion is estimated. The function and adjustment of the spectrometer is discussed.
TL;DR: In this article, the effect of electron correlations on the Auger spectra from the substitutionally disordered narrow-band metal alloys with partially filled bands is studied within the degenerate Hubbard model.
Abstract: The effect of electron correlations on the Auger spectra from the substitutionally disordered narrow-band metal alloys with partially filled bands is studied within the degenerate Hubbard model. Perturbation theory is used limited to the second order in U/w (U Coulomb integral, w bandwidth) for the calculation of the one-particle Green function, and the ladder approximation for the two-particle Green function. The effect of disorder is included within the single-site approximation. The theory is illustrated on a simple model of the copper-nickel alloy.
Der Einflus der Elektronenkorrelationen auf die Augerspektren der substitutionell-ungeordneten Legierungen von Metallen mit teilweise gefullten schmalen Bandern wird in Rahmen eines entarteten Hubbard-Modells untersucht. Storungstheorie zweiter Ordnung in U/w (U Coulomb Integral, w Bandbreite) wird fur die Berechnung der Einteilchen-Greenfunktion benutzt sowie die Leiterapproximation fur die Zweiteilchen-Greenfunktion. Der Einflus der Fehlordnung wird in die Einzentrennaherung einbezogen. Die Theorie wird fur ein einfaches Modell der Kupfer–Nickel-Legierung dargestellt.
TL;DR: The temporal characteristics of the motor potentials and the neuronal activity suggest a rostro-caudal activation of the striatum during pecking in unrestrained pigeons.
Abstract: So-called motor potentials and changes in the neuronal activity of various regions of the striatum during pecking were studied in 50 unrestrained pigeons. The motor potentials which appeared during pecking were recorded from all regions of the striatum. Neurons of the striatum changed their level of activity during pecking (they became more active for the most part). The temporal characteristics of the motor potentials and the neuronal activity suggest a rostro-caudal activation of the striatum. The amplitude of the evoked potential of the tectum in response to a flash of a light changed during pecking movements.
TL;DR: In this article, simple qualitative reasoning based on symmetry arguments is used to study the reconstruction of the W(001) surface and it is assumed that the inherent lattice instability is caused mainly by electron-phonon coupling via Shockley surface states from the vicinity of the Fermi energy.
Abstract: Simple qualitative reasoning based on symmetry arguments is used to study the reconstruction of the W(001) surface. It is assumed that the inherent lattice instability is caused mainly by electron-phonon coupling via Shockley surface states from the vicinity of the Fermi energy. The introduction of the local C 4v symmetry enables to analyze the respective electron-phonon matrix elements and leads to the conclusion that in-plane reconstruction modes M 5 and X 3 are more perspective than the buckled ones.
TL;DR: In this paper, both the unperturbed and perturbed balance equations of the solidification front (mathematically modelled as the non-autonomous discontinuity surface at the macroscopic level) are evaluated in general forms in the frame of the standard linear perturbation analysis.
Abstract: Both the unperturbed and the perturbed balance equations of the solidification front (mathematically modelled as the non-autonomous discontinuity surface at the macroscopic level) are evaluated in general forms in the frame of the standard linear perturbation analysis. The balances of the energy, total and partial masses at the solidification front are determined as examples.
TL;DR: In this article, the dynamic susceptibility of a 3D metal is obtained in the Brooks tight-binding mean-field approximation (including orbital moments and spin-orbit interaction), compatible with the Kittel-Van Vleck g-factor theory and the classical phenomenology of anisotropy shifts.
Abstract: Dynamic susceptibility of a 3d metal is obtained in the Brooks tight-binding mean-field approximation (including orbital moments and spin-orbit interaction). The result is compatible with the Kittel-Van Vleck g-factor theory and the classical phenomenology of anisotropy shifts. Values ofg for Ni and Fe are computed numerically. Dominant contributions to anisotropy in Ni are derived from Bloch states with wave vectors close to 〈001〉 and orbital moments “quenched” along these axes. The role of non-collinearity of spin alignment in Bloch representation is pointed out.