Showing papers by "Academy of Sciences of the Czech Republic published in 1971"
TL;DR: In this paper, the importance of the correct selection for the assessment of the progress of the reaction and the acquisition of representative experimental data, as well as the effect of non-isothermal conditions and possible change of the equilibrium on the kinetic equation are stressed.
1,249 citations
TL;DR: In this paper, the authors presented a linear plot of the TG trace corresponding to a heterogeneous process which proceeds with a constant increase of the temperature, where α is the fraction decomposed, function g(α) is given by the rate controlling process and function p( x ) depends on its activation energy.
273 citations
01 Jan 1971
TL;DR: In this paper, the isotopic exchange of oxygenl8O between gaseous oxygen and solids is studied and a review is concerned with the isotope exchange (IE) of oxygen
Abstract: This review is concerned with the isotopic exchange (IE) of oxygenl8O between gaseous oxygen and solids.
103 citations
74 citations
TL;DR: In this paper, a method for determining the orientations of domain walls in ferroelectrics which are permissible under the condition that neighbouring domains must be mechanically compatible is presented. But this method has not been applied to all 88 ferroelectric species in which the polarization is the parameter of the transition.
Abstract: A previously developed method makes it possible to determine the orientations of domain walls in ferroelectrics which are permissible under the condition that neighbouring domains must be mechanically compatible. In this paper, the method has been applied to all 88 ferroelectric species in which the polarization is the parameter of the transition. Types of permissible walls and their orientations are listed in form of tables. Cases where no walls fulfil the compatibility conditions are shown.
55 citations
46 citations
Abstract: The phase transitions in boracites are analysed by using the group-theoretical formulation of the Landau theory of phase transitions. It is shown that the orthorhombic, monoclinic and trigonal phase transitions could be induced by the same irreducible representation of the space groupTd5 with the star determined by the wave vectork=1/2(b1+b2). The corresponding free energy function is constructed and the symmetry of normal modes is discussed.
43 citations
TL;DR: In this article, a thermodynamic theory of the cubic-orthorhombic phase transition in boracites is developed and the temperature dependences of dielectric, piezoelectric and elastic constants near the phase transition temperature are derived.
Abstract: A thermodynamic theory of the cubic-orthorhombic phase transition in boracites is developed. The temperature dependences of dielectric, piezoelectric and elastic constants near the phase transition temperature are derived. Since the parameter of the phase transition is not the polarization, the spontaneous strains and polarization are not related by electromechanical constants. Magnetic properties of boracites are not considered.
42 citations
01 Dec 1971
TL;DR: Theoretical equations for the pressure drop of high-porosity fibrous aerosol filters for low-speed Newtonian flow are summarized and the relations between them are discussed in this article.
Abstract: Theoretical equations for the pressure drop of high-porosity fibrous aerosol filters for low-speed Newtonian flow are summarized, and the relations between them are discussed. Using these equations the general character of the dependence of the pressure drop on the gas pressure (pressure characteristics) is analyzed over the whole range of Knudsen numbers. The dimensionless equations describing the reduction of the pressure drop with decreasing gas pressure are derived. Analyzing these equations, it is concluded that the pressure-drop reduction is dependent on three factors: the character of flow through a filter at normal pressure (continuum, slip, transient and free molecule flow), the dilution (reduction of the gas pressure), and porosity of the filter. The theory is checked against available experimental data.
41 citations
37 citations
TL;DR: High and reproducible antibody response to miligram quantities of 2,4‐dinitrophenyl (DNP)‐conjugated bovine IgG was elicited in pigs with the aid of a novel adjuvant composed of aluminium hydroxide, paraffin oil and Sorbitan trioleate.
Abstract: High and reproducible antibody response to miligram quantities of 2,4-dinitrophenyl (DNP)-conjugated bovine IgG was elicited in pigs with the aid of a novel adjuvant composed of aluminium hydroxide, paraffin oil and Sorbitan trioleate (Al-Span-Oil) Repeated injections of antigen produced antibody levels up to 8 mg per ml of serum The antibody level reached the maximum around the 12th day after first antigen injection, but around the 7th day after subsequent antigen injection Isolated anti-DNP antibody was found to be chemically heterogeneous It bound ϵ-DNP-lysine with a mean association constant of about 106 M−1
TL;DR: A circadian rhythm in pineal serotonin content was found not only in young rats maintained in diurnal lighting conditions but also in rats kept from birth in continuous darkness, suggesting light or an environmental light-dark cycle is not essential for the induction of a serotonin rhythm after birth.
Journal Article•
TL;DR: The oleoresin of Copaifera langsdorfii L has been found to contain some sesquiterpenic hydrocarbons and diterpenics.
TL;DR: In this paper, single crystals of binary solid solutions of TGS and TGFB have been grown and morphological descriptions of crystals are presented and the growth rates under comparable conditions are determined.
TL;DR: In this article, the complex damping constant of an ultrasonic wave in a ferroelectric crystal which is non-piezoelectric above the Curie temperature was calculated in the hydrodynamic approximation.
Abstract: The complex damping constant of an ultrasonic wave in a ferroelectric crystal which is non-piezoelectric above the Curie temperature was calculated in the hydrodynamic approximation. The interaction of the ultrasound with polarization waves is expressed in terms of electrostrictive constants. Ferroelectrics both of the relaxation and displacive type are treated in an unified way. The frequency and temperature dependence of the sound attenuation constant and frequency shift was studied in detail for two typical representatives of ferroelectrics, i.e. barium titanate and tri-glycine sulphate.
TL;DR: The serotonin content in the rat pineal gland responded very quickly to changes in lighting conditions, and was not due to stress properties of an abrupt light change, because another stress agent, cold, did not cause any increase.
TL;DR: A computer model is presented explaining the observed dependency of the IH shape on the MI duration in terms of the change in the mean frequency of common input process.
Abstract: The spontaneous nerve impulse activity of 354 neurons of the mesencephalic reticular formation resp. the superior colliculus of unanesthetized curarized rats resp. cats has been recorded by microelectrodes and processed by means of a LINC computer. A relationship between the shape of interimpulse interval histogram (IH) and the mean interimpulse intervals (MI) of the same spike train has been found. Neurons with long MI's (low frequency of firing) are never characterized by symmetrical IH's, the exponential IH (characterizing random occurrence of impulses) being the most common in these cases. Neurons with symmetrical IH's are usually those with short MI's (fast firing rate). Longlasting recordings with changing MI show that the shape of IH's may not be considered in general a stable feature of certain neurons (in the majority of cases it changes together with the MI). Neurons with symmetrical IH's and short MI's may not be found in the superficial layers but in the depth of the superior colliculus only (having probably like the reticular formation integrative functions). A computer model is presented explaining the observed dependency of the IH shape on the MI duration in terms of the change in the mean frequency of common input process.
TL;DR: The result is a simple rule permitting the determination of the column volume and volume and slope of the gradient which are the most suitable for the fractionation of a given amount of a certain mixture.
TL;DR: Evidence is provided showing that tosylphenylalanyl chloromethane (TPCK, 1-chloro-4-phenyl-3tosyl-amido-2-butanone) is a selective irreversible inhibitor of the complex of Sr S3 -factors in the cellfree protein-synthetizing system from B. sfearothermophilus.
TL;DR: In this paper, a model of helium atom possessing four excitation levels (23S, 21S, 23P, 21P) is assumed and the calculated volt-ampere characteristic is compared with an experiment and the relative densities of excited atoms are derived.
Abstract: On the basis of good knowledge of the energy distribution function of electrons corresponding to the conditions of low-current discharge the electrons as well as the excited helium atoms are balanced. A model of helium atom possessing four excitation levels (23S, 21S, 23P, 21P) is assumed. The calculated volt-ampere characteristic is compared with an experiment and the relative densities of excited atoms are given. For these quantities approximate formulae are derived. The laws of similarity, ionization mechanism and energy balance of the electron gas are discussed.
TL;DR: It has been proposed that Na complexes with the above polypeptides to form a more active molecule by alteration of the steric conformation of the peptide chain.
TL;DR: The aim of this work was to fractionate and to characterize the population of isolated y- chains, i.e. to examine the heterogeneity of y-chains under conditions where theogeneity of light chains does not interfere.
TL;DR: In this article, the Schmid curves of carbon-rich specimens were measured and the changes of the curves caused by increased carbon content were discussed from the point of view of the low temperature induced cross-slip.
Abstract: Specimens with 18 ppm and 100 ppm carbon of different orientations were deformed by compression (έ∼1·1×10−4 s−1) at the temperatures 150 °K, 195 °K, 293 °K, 393 °K and 483 °K. The measuredΨ(χ) andτ(χ) curves are presented. The changes of the curves caused by increased carbon content are discussed from the point of view of the low temperature induced cross-slip. Deviations from the Schmid law of critical resolved shear stress are found for both carbon contents. The dependence of the CRSS on temperature for specimens of standard purity has a slightly different course for orientationχ=−30° than for orientationsχ=0° andχ=+30°. These deviations are discussed in terms of the influence of normal stress on the slip. The course ofΔτ (difference between the CRSS in the MRSS plane for specimens with 100 ppm and 18 ppm of carbon) onχ is discussed using different models of lattice hardening due to interstitial impurities. These models can also be applied to the explanation of deviations ofτ(χ) curves from the Schmid law.
TL;DR: In this paper, the authors performed a systematic study of the wave phenomena in the nitrogen glow discharge at the pressures from 0·1 to 5 Torr and the currents from 0.1 to 40 mA. They concluded that at least three different varieties of ionization waves exist in this region and three independent dispersion curves were observed.
Abstract: The systematic study of the wave phenomena was performed in the nitrogen glow discharge at the pressures from 0·1 to 5 Torr and the currents from 0·1 to 40 mA. From the measurement of the phase and group velocities and Novak's potentials in dependence on pressure and current changes it was concluded, that at least three different varieties of ionization waves exist in this region and three independent dispersion curves were observed. Relations between various types and varieties of ionization waves and their connection with possible ionization processes were studied.
TL;DR: In this paper, the ferromagnetic resonance linewidth ΔH in plane configuration was measured in single crystal discs of Fe-2·2% Si at frequency 36·14 GHz.
Abstract: The ferromagnetic resonance linewidthΔH in “in plane” configuration was measured in single crystal discs of Fe-2·2% Si at frequency 36·14 GHz. Several methods of electrolytic and chemical polishing were used to minimize the effects of sample surface irregularities. By rotating the external field in the plane of the discs ((110) plane) the linewidth of well polished samples was found to be isotropic within the experimental errors (about 5%). Spurious anisotropy of linewidth was found in some imperfectly polished samples.
01 Jan 1971
TL;DR: In this paper, cyclic voltammetry was used for monitoring of cysteine and ascorbic acid in the kidney in vivo after intravenous injection of these substances.
Abstract: Electrochemical oxidation of cysteine, reduced glutathione and ascorbic acid at a platinum electrode was studied in phosphate buffer solution at pH 7.2 using cyclic voltammetry. This method makes it possible to obtain reproducible oxidation waves of these substances dissolved in blood serum. Cyclic voltammetry was also used for monitoring of cysteine and ascorbic acid in the kidney in vivo after intravenous injection of these substances. In this way cysteine or ascorbic acid function as electrochemical indicators, for example, for assessment of blood supply to the kidney.