Showing papers by "Academy of Sciences of the Czech Republic published in 1978"
TL;DR: In this paper, the amplitudon and phason branches are calculated and their activity in infrared and Raman spectra is determined, and the observed static dielectric anomaly is explained by softening of the infrared active phason mode when the wavevector of the incommensurate wave approaches its commensurate value.
Abstract: Low-frequency normal modes of the incommensurate structure are discussed using the example of K2SeO4. The amplitudon and phason branches are calculated and their activity in infrared and Raman spectra is determined. The observed static dielectric anomaly is explained by softening of the infrared-active phason mode when the wavevector of the incommensurate wave approaches its commensurate value.
56 citations
TL;DR: In this paper, the authors describe two computer programs useful for the evaluation of heterogeneous kinetics, namely, ALANTA and SQUEST, which determine the kinetic mechanism which is the most appropriate to a given nonisothermal kinetic curve and evaluate the corresponding kinetic parameters.
40 citations
TL;DR: In this paper, the low-field magnetic properties of amorphous (Fe1−xNix)80P10B10 are examined by measuring the local magnetic reversal field and the pinning field as function of position.
Abstract: The low-field magnetic properties of amorphous (Fe1−xNix)80P10B10 are examined by measuring the local magnetic reversal field and the pinning field as function of position. Also measurements of magnetic anisotropy using FMR are reported. The observed magnetic behaviour is discussed generally. The magnetization reversal for the ideal parts of the wires may be described by the process of growth of nuclei present.
34 citations
TL;DR: The domain structure of a TGS crystal can be seen under a polarizing microscope on a cleaved crystal surface covered with the nematic MBBA crystal in this paper, where the electric field can be applied on the TGS sample and slow domain switching directly observed.
Abstract: The domain structure of a TGS crystal can be seen under a polarizing microscope on a cleaved crystal surface covered with the nematic MBBA crystal. The domains with the minus end of Ps at the surface appear as dark areas at the extinction of the TGS sample (which corresponds to homeotropic alignment of liquid crystal molecules), in contrast with the antiparallel ones, which are bright (due to the parallel orientation of molecules). For observation of the domain structure close to the phase transition, MBBA + EBBA mixture is to be used. The electric field can be applied on the TGS sample and slow domain switching directly observed.
34 citations
TL;DR: In this article, a crystal field analysis of the reported optical spectra of Nd3+ in the series of aluminium and gallium garnets LuAG, YAG, GGG, LuGG, and YGG is presented.
Abstract: A crystal field analysis of the reported optical spectra of Nd3+ in the series of aluminium and gallium garnets LuAG, YAG, GGG, LuGG, and YGG is presented. The reliability of the crystal field parameters determined in this way is confirmed by comparison with ESR g-values given in the literature. The results obtained represent a basis for a further study of the relation between the crystal field parameters of rare earths in garnets and the structure of the coordination dodecahedron.
[Russian Text Ignore]
32 citations
TL;DR: In this paper, a method of high-performance liquid chromatography was developed for the separation and quantitative analysis of a mixture of ergot alkaloids on MicroPak NH2 columns using isocratic and gradient elution.
31 citations
TL;DR: In this article, a numerical solution of the Boltzmann equation for a weakly ionized discharge in O2 ranging from 5 Td to 200 Td was presented, and a comparison of the results on the collisional rates with the values available in the literature was performed as well.
Abstract: The calculations of the distribution function of electrons and the collisional rates were carried out on the basis of a numerical solution of the Boltzmann equation for a weakly ionized discharge in O2 rangingE/N from 5 Td to 200 Td. The distribution function, Townsend ionization and dissociative attachment coefficients calculated were found to be in good agreement with experiments. A comparison of the results on the collisional rates with the values available in the literature was performed as well.
30 citations
TL;DR: In this paper, the effect of the viscosity of the injected polymer solution in gel permeation chromatography was investigated using samples of polystyrene standards with molecular weights above the exclusion limit of the column packing used.
27 citations
TL;DR: In this paper, the anodic stripping determination of Te(IV) using a rotating glassy carbon disc electrode is described, which enables the determination of 10 μg Te in the presence of 25 mg Pb and Sb and 0.5 mg Ag, Cu, Bi, As, Sn, Cd, Zn with reproducible results and error ±5%.
16 citations
TL;DR: In this paper, the effect of noncentrosymmetric anharmonic vibrations of atoms in cuprous chloride is investigated by X-ray diffraction on a single crystal at room temperature.
Abstract: The effect of noncentrosymmetric anharmonic vibrations of atoms in cuprous chloride is investigated by X-ray diffraction on a single crystal at room temperature. The observed structure factors are found to be sufficiently sensitive to anharmonic vibrations of atoms and the parameters of the effective one-atom potential fields are determined.
Nichtzentrosymmetrische anharmonische Gitterschwingungen in CuCl werden mittels Rontgendiffraktometrie an Einkristallen bei Raumtemperatur untersucht. Es wird festgestellt, das die Strukturfaktoren zur Ermittlung der Parameter der anharmonischen Schwingungen der Atome genugend empfindlich sind.
16 citations
TL;DR: In this paper, a simple procedure of evaluation of experimental data from the elution volumes of the maxima of elution curves and from graphically determined chromatogram widths is used.
TL;DR: In this article, the possibility of using this concept for explanation of successive structural phase transitions in Rochelle salt and langbeinites is discussed, and physical requirements for being reasonable to consider such a hypothetical phase are pointed out.
Abstract: Examples known so far of structural phase transitions which can be treated as an instability of a hypothetical parent phase are enumerated. Physical requirements for being reasonable to consider such hypothetical phase are pointed out. The possibility of using this concept for explanation of successive structural phase transitions in Rochelle salt and langbeinites is discussed.
TL;DR: In this paper, the phase diagram of the binary system PbO-Ga 2 O 3 was determined by means of DTA and X-ray measurement, and the existence of compound PbGa 2O 4 in the investigated system was confirmed.
TL;DR: It appears possible that the impaired response of the old laboratory rodents to various stimuli reflects, besides other factors, the distortion of transport processes caused by the accumulation of specific collagen types.
TL;DR: In this paper, the decay of 4.8 min 160 Yb has been investigated by means of Ge(Li) detectors, toroidal and magnetic-lens β-spectrometers and scintillation counters.
TL;DR: In this paper, the problem of X-ray diffraction on a crystal containing a misfit boundary is solved using dynamical theory (plane wave approximation, Laue case of diffraction).
Abstract: X-ray diffraction on a crystal containing a misfit boundary is solved using dynamical theory (plane wave approximation, Laue case of diffraction). Resulting explicit formulas for complex amplitudes of all diffracted and forward diffracted waves may be used for direct calculation of diffracted and transmitted intensities and of contrast in diffraction topographs.
Rontgen-Strahl-Beugung an einem Kristall, der eine ebene Gitterstorung enthalt, wird unter Anwendung der dynamischen Theorie (Naherung der ebenen Welle, Laue-Fall der Beugung) gelost. Die resultierenden expliziten Formeln fur die komplexen Amplituden aller reflektierten und durchgestrahlten Wellen konnen fur die direkte Berechnung der Intensitaten und des Kontrastes in den topographischen Aufnahmen angewendet werden.
TL;DR: In this article, special cases (coherent boundary; interface parallel to the entrance surface) and extreme cases (ΔH = 0 or large; intersection of the interface with the entrance and exit surfaces) are discussed.
Abstract: Using results of Part I, special cases (coherent boundary; interface parallel to the entrance surface) and extreme cases (ΔH = 0 or large; intersection of the interface with the entrance and exit surfaces) are discussed.
Unter Anwendung der Ergebnisse des Teils I werden Sonderfalle (koharente Grenze; Grenzflache parallel zur Eintrittsoberflache) und Grenzfalle (ΔH = 0 oder gros; Schnitt der Grenzflache mit der Eintritts- und Austrittsoberflache) untersucht.
TL;DR: The frequency dependence of the electric conductivity of glassy CdAs2+six and As2+Sbx was studied in this paper, where the frequency-dependent conductivity increases with frequency as ωs with s ≈ 12.
Abstract: The frequency dependence of the electric conductivity of glassy CdAs2+Six and CdAs2+Sbx (with x = 0 to 06) is presented The frequency-dependent conductivity denoted by σF increases with frequency as ωs with s ≈ 12 Experimental values of the relative dielectric constant and its dependence on chemical composition are given also Gold contacts do not influence the measured conductivity in the whole frequency range (102 to 108 Hz), but the capacitance is influenced by the contact layer at lower frequencies (up to 106 Hz) The dielectric constant is correlated to the gap according to the Moss rule
On presente la variation de la conductivite electrique des semiconducteurs vitreux CdAs2+Six et CdAs2+Sbx (ou x varie de 0 a 0,6) avec la frequence La conductivite dependante de la frequence, σF, suit la relation σF(ω)∼ ωs avec s ≈ 1,2 On montre aussi les valeurs experimentales de la constante dielectrique et sa variation avec la composition chimique Les contacts electriques (Au) n'ont pas d'influence sur la conductivite mesuree dans toute la gamme des frequences (102 a 108 Hz) mais ils ont une influence sur la capacite dans la gamme des frequences basses (jusqu'a 106 Hz) La constante dielectrique est liee au gap par la regle de Moss
TL;DR: Polypeptides reduce the number of binding sites on DNA available for actinomycin D binding, and the extent of this change depends mainly on the content and distribution of basic lysine residues.
Abstract: Complexes of DNA with histone H1 and random and sequential polypeptides containing 30–100% of lysine were studied using actinomycin D as a probe. The binding of actinomycin D was measured by spectrophotometric titration in 0.15M NaCl and in 0.01M Tris buffer. The excluded-site model was used for the evaluation of binding data. Polypeptides reduce the number of binding sites on DNA available for actinomycin D binding. The extent of this change depends mainly on the content and distribution of basic lysine residues. Of the hydrophobic residues constituting the peptides, only leucine strongly depresses the actinomycin D binding. The helix-forming and helix-breaking amino acid residues are without effect.
TL;DR: In this article, the authors measured the constant Ku of magnetic uniaxial anisotropy in sputtered amorphous Gd-Co films by different methods and found significant discrepancies between the results of static and of ferromagnetic resonance measurements, especially in the region of magnetic compensation.
Abstract: The constant Ku of magnetic uniaxial anisotropy is measured in sputtered amorphous Gd–Co films by different methods. Considerable discrepancies are found between the results of static and of ferromagnetic resonance measurements, especially in the region of magnetic compensation. The reasons for the different results are probably inhomogeneous composition and microstructure of the films and slightly field-dependent magnetic parameters of amorphous Gd–Co. To get more insight in the origin of Ku in amorphous Gd–Co, measurements in a broad temperature range are performed before and after annealing. The results show clearly two main contributions to Ku. Atomic short range order leads to positive Ku and disappears during annealing. Stresses in the films produce negative Ku at temperatures below the temperature during preparation and are not significantly influenced by annealing.
Die Konstante Ku der magnetischen uniaxialen Anisotropie wird in gesputterten amorphen Gd–Co-Schichten mit verschiedenen Methoden gemessen. Ferromagnetische Resonanz und statische Methoden ergeben stark unterschiedliche Werte, insbesondere in der Nahe der magnetischen Kompensation. Inhomogene Zusammensetzung und Mikrostruktur sowie eine leichte Feldabhangigkeit der magnetischen Eigenschaften des Gd–Co tragen zu diesen Diskrepanzen bei. Um Aufschlus uber die Natur der Anisotropie zu gewinnen, wird daher Ku in einem grosen Temperaturbereich vor und nach dem Tempern gemessen. Die Ergebnisse zeigen zwei Hauptursachen fur Ku. Anisotrope Nahordnung fuhrt zu positivem Ku und verschwindet wahrend des Temperns. Spannungen in den Schichten geben unterhalb der Herstellungstemperatur einen negativen Beitrag, der sich durch das Tempern nicht wesentlich andert.
TL;DR: In this paper, the resonance field, linewidth, and asymmetry of the absorption curve are computed as a function of the ratio a/δ of the radius of cylinder to the skin depth.
Abstract: The FMR parameters of an infinitly long ferromagnetic cylinder with arbitrary value of conductivity are calculated neglecting the exchange term in the equation of motion. For low resistivity magnetic materials the resonance field, linewidth, and asymmetry of the absorption curve are computed as a function of the ratio a/δ of the radius of cylinder to the skin depth . These dependences are compared with the experimental results on low-resistivity manganese-iron ferrites. Further an approximative formula is derived for the radiation contribution to linewidth, and for the resonance field shift depending on conductivity.
TL;DR: In this article, a system of wedge disclinations parallel to a free surface is used to describe stresses and magnetostrictive displacements caused by a parallel system of domain wall junctions of two 90 and one 180 walls in a half-space.
Abstract: A system of wedge disclinations parallel to a free surface is used to describe stresses and magnetostrictive displacements caused by a parallel system of domain wall junctions of two 90‡ and one 180‡ walls in a half-space. The local inclination of the surface is determined.
01 Jan 1978
TL;DR: Methods for the covalent binding of imidazole to poly-(hydroxyethyl-methacrylates) and polysaccharides are described and their applications for affinity chromatography of hemoproteins and hemoglobin/ myoglobin are described.
Abstract: Methods for the covalent binding of imidazole to poly-(hydroxyethyl-methacrylates) and polysaccharides are described These matrices are suitable for affinity chromatography of hemoproteins (hemoglobin/ myoglobin, cytochrome P-450/cytochrome P-420 etc) The separation effectivity depends on the spacer length of the matrix, pH and temperature Ligand specific contacts (coordinative binding between hemin iron and imidazole) are essential in case of a short spacer Long spacers are responsible for unspecific interactions Separation of hemoglobin/myoglobin is possible also by means of matrices containing ω-aminoalkyl groups
TL;DR: The marked labelling of the gliomesenchymal scar by colloidal-iron indicates furthermore that this newly vascularized tissue with leaky capillaries may be a source of perifocal edema.
Abstract: Two blood-borne tracers, Evans-blue albumin (EBA) and colloidal-iron (Ferrlecit) were applied to visualize the development of perifocal edema in experimental epilepsy induced by cobalt-gelatin (Co-gelatin). This model is known to produce central necrosis with gliomesenchymal scar and peripheral transitory zone in the brain cortex. Characteristic red fluorescence of EBA was detected diffusely in the necrotic area surrounding the Co-gelatin implant and EBA labelled individual neurons reflecting cell membrane injury in the transitory zone. The colloidal iron tracer was localized mainly in the gliomesenchymal scar. It is proposed that neurons with altered membrane permeability to EBA in the transitory zone may play a role in the genesis of epileptic spike activity. The marked labelling of the gliomesenchymal scar by colloidal-iron indicates furthermore that this newly vascularized tissue with leaky capillaries may be a source of perifocal edema.
TL;DR: In this paper, the applicability of two different approaches to diffusion in a force field is examined for the steady state dislocation motion in solid solutions, and the results for a general interaction potential are derived in the one-dimensional case and both approaches are compared using numerical calculations for a chosen potential.
Abstract: The applicability of two different approaches to diffusion in a force field is examined for the steady state dislocation motion in solid solutions. The results for a general interaction potential are derived in the one-dimensional case and both approaches are compared using numerical calculations for a chosen potential.
Die Anwendungsmoglichkeit von zwei verschiedenen Naherungen zur Diffusion im Kraftfeld wird fur die stationare Versetzungsbewegung in einer festen Losung untersucht. Die Ergebnisse fur allgemeine Wechselwirkung werden fur den eindimensionalen Fall abgeleitet und beide Naherungen werden mit Hilfe von numerischen Berechnungen fur ein gewahltes Potential verglichen.
TL;DR: In this paper, the temperature and frequency dependence of the linear elastic constants for crystals of arbitrary symmetry near a second-order structural phase transition are derived on the basis of a thermodynamic potential including time and space (one-, two-, or three-dimensional) fluctuations of the order parameter.
Abstract: Relations for the temperature and frequency dependence of the linear elastic constants for crystals of arbitrary symmetry near a second-order structural phase transition are derived on the basis of a thermodynamic potential including time and space (one-, two-, or three-dimensional) fluctuations of the order parameter. The calculation is based on a perturbation expansion with respect to the small deformation tensor components and is given in detail for a two-component order parameter. The results are used for the explanation of the elastic constant anomalies of GMO and Hg2Cl2. The influence of the higher-order interaction terms above or below the phase transition is investigated with an application to the case of Hg2Cl2.
Des expressions pour les variations des constants elastiques des cristaux n'import quelle symetrie en fonction de la temperature et de la frequence au voisinage d'une transition structurelle du second ordre sont derivees a la base des fluctuations de temps et d'espace (d'une, de deux ou de trois dimensions) du parametre d'ordre avec utilisation du developpement de perturbation d'apres des elements du tenseur de deformation. Ces expressions sont liees avec des coefficients de developpement du potentiel thermodynamique. Le calcul detaille est fait pour le parametre d'ordre de deux elements et les resultats sont utilises pour l'explication des variations critiques des constantes elastiques de GMO et de Hg2Cl2. L'influence des termes de couplage d'ordre plus haut (au-dessus ou au-dessous de la transition) est examinee et elle est appliquee dans le cas de Hg2Cl2.
TL;DR: In this article, the influence of probe thickness and contamination on the measurement of the electron energy distribution function was studied in a homogeneous oxygen positive column, and the curve f(U) obtained by a thin cleaned probe was compared with the curve calculated by other authors.
Abstract: The influence of the probe thickness and contamination on the measurement of the electron energy distribution function is studied in a homogeneous oxygen positive column. The curve f(U) obtained by a thin cleaned probe is compared with f(U) calculated by other authors. The agreement is very good.
TL;DR: The absorption in the vacuum and near ultraviolet region of CaF2 crystals containing lead and oxygen has been measured in this article, and two main absorption bands at 155 and 202 nm are presumably due to lead centers and the band at 206 nm to oxygen.
Abstract: The absorption in the vacuum and near ultraviolet region of CaF2 crystals containing lead and oxygen has been measured. Two main absorption bands at 155 and 202 nm are presumably due to lead centres and the band at 206 nm to oxygen. The nature of the weak band at 166 nm remains obscure. The absorption below 145 nm is probably due to excitons.