Showing papers by "Academy of Sciences of the Czech Republic published in 1974"
TL;DR: In this paper, a theoretical study of the statistical mechanical description of systems composed of non-spherical convex molecules is made, where the averaged contact correlation function is introduced and approximate expressions for the averaged correlation functions are given in terms of the geometric functionals of hard convex bodies.
Abstract: A theoretical study of the statistical mechanical description of systems composed of non-spherical convex molecules is made. Thermodynamic functions of one-component and multicomponent systems of particles interacting via the pair potential of the Kihara core type are expressed by integrals over the minimum distance between two interacting convex bodies and three angles characterizing the convex body geometry. The approach is applied to the hard convex body system where the averaged contact correlation function is introduced. Exploiting ideas of the scaled particle theory the approximate expressions for the averaged correlation functions are given in terms of the geometric functionals of hard convex bodies.
159 citations
TL;DR: The geographical distribution of Ordovician acritarchs is not uniform as discussed by the authors, and two main provinces can be distinguished: (1) the Baltic province, characterized by the prevalence of acanthomorphids, and (2) the Mediterranean province, characterised by the occurrence of diacromorphids.
71 citations
TL;DR: In this paper, a method for the calculation of rays and geometrical spreading of seismic body waves propagating in laterally inhomogeneous media with curved interfaces is suggested. But this method is based on a system of ordinary differential equations of the first order and the initial conditions for these quantities at the interface are derived.
Abstract: Summary
Methods for the calculation of rays and geometrical spreading of seismic body waves propagating in laterally inhomogeneous media with curved interfaces are suggested. Seismic rays and geometric spreading are described by a system of ordinary differential equations of the first order. When the ray impinges on an interface, certain quantities of the above system change discontinuously. The initial conditions for these quantities at the interface are derived. Once the geometrical spreading has been determined the computation of ray amplitudes is easy.
54 citations
TL;DR: In this article, the authors attributed the excitation and recombination processes in D-A complexes formed of substitutional oxygen donors ON and aluminum vacancies V and proposed a model of these centers.
Abstract: Emission luminescence spectra of A1N with oxygen impurity are composed of several overlapping bands ranging from 2.37 eV to 3.51 eV. The intensity of these bands depends on the excitation conditions. The Stokes shift of corresponding excitation bands is ∼0.93 eV; this shift is compatible with the experimental half-width of individual bandsΘ ∼ 0.46 eV. The observed complex spectra are ascribed to the excitation and recombination processes in D-A complexes formed of substitutional oxygen donors ON and aluminum vacancies V
Al
. Tentative models of these centers are proposed.
35 citations
TL;DR: In this article, a continuous free-flow apparatus for thin-layer zone electrophoresis and adaptations for separations by isotachophoresis, and by isoelectric focusing are described.
28 citations
TL;DR: It is suggested that the early and late antibodies represent closely related subclasses of porcine IgG differing by the shape and/or flexibility of the molecule.
23 citations
22 citations
TL;DR: It is suggested that the isolated fraction represents a mixture of alpha‐ MSH and 1–13 ACTH, and that alpha‐MSH may be an acetylated end‐product of ACTH cleavage in the pituitary.
Abstract: . Crude Van Dyke protein prepared from frozen bovine posterior pituitary glands was treated with formic acid to release small bound and adsorbed peptides. Gel filtration, continuous free-flow electrophoresis and descending paper electrophoresis were used to separate the small peptides into successively purer fractions which were assayc sdfor pressor, utero tonic, natriuretic and melanocyte stimulating activities under double blind conditions. The highest peak of natriuretic activity was associated with only a small pressor and no uterotonic activities, and the same fractions contained a ninhydrin-positive spot on paper electrophoresis, the mobility of which at pH 5.6 was similar to that of alpha-melanocyte stimulating hormone (MSH) and ACTH-(i-13-amide)-tri-decapeptide (1–13 ACTH-amide) but differed from vasopressin and oxytocin. Material from this spot had an amino acid composition which corresponded with the first 13 residues of ACTH. Quantitative bioassay of the final fraction in the frog demonstrated a melanotropic activity which, however, was lower than would have been expected for pure alpha-MSH. The natriuretic activity of the isolated fraction was far higher than the potency of separately administered peptides which might be present: arginine-vasopressin, alpha-MSH or 1–13 ACTH. It is suggested that the isolated fraction represents a mixture of alpha-MSH and 1–13 ACTH, and that alpha-MSH may be an acetylated end-product of ACTH cleavage in the pituitary.
21 citations
TL;DR: In this paper, experimental observations on the motion of s prime variety ionization waves in neon are reported, and the results are explained in terms of mode-jumping and forced modulation due to nonlinear effects.
Abstract: Experimental observations on the motion of s prime variety ionization waves in neon are reported. The results are explained in terms of mode-jumping and forced modulation due to nonlinear effects.
13 citations
TL;DR: The seasonal variation in the occurrence of sporadic-E measured by ionosondes in temperate northern and southern latitudes during a 6-yr period, is compared with the seasonal variation of the zonal wind system and with meteor activity over both hemispheres as discussed by the authors.
12 citations
TL;DR: It is suggested that the disappearance of tyrosyl residues with age may be due to the conversion of these into a cross-linking element of the Pummerer's ketone type.
TL;DR: In this article, it is suggested that the one-electron oxidation of (π-Cp) 2 TiBH 4 produces oxygen radicals, which can initiate homogeneous hydrogeneation of olefins.
TL;DR: Some of the compounds which enhanced hepatic uridine kinase activity concomitantly suppressed the activity of the enzyme in the thymus, while daunoruhicin adriamycin and thioacetamide were much less effective in this respect.
TL;DR: An efficient algorithm for the integration of stiff systems of ordinary differential equations based on the boundary value technique is derived and the automatic step-size control procedure can be easily adapted.
Abstract: An efficient algorithm for the integration of stiff systems of ordinary differential equations based on the boundary value technique is derived. The automatic step-size control procedure can be easily adapted. Results for a very stiff problem are compared with those obtained by other methods and the high effectiveness of the method is shown.
TL;DR: The effect of some factors (sugar source, concentration of substrates, pH) on biosynthesis of 1-hydroxy-2-(β-d-glucopyranosyloxy)anthraquinone was studied and optimum conditions for the microbial glucosidation were determined.
Abstract: Corresponding mono-β-d-glucosides were obtained by fermentation ofStreptomyces aureofaciens B 96 with four isomeric dihydroxyanthraquinones (alizarin, quinizarin, chrysazin and anthraflavin). The effect of some factors (sugar source, concentration of substrates, pH) on biosynthesis of 1-hydroxy-2-(β-d-glucopyranosyloxy)anthraquinone was studied and optimum conditions for the microbial glucosidation were determined.
TL;DR: The results obtained represent a reliable basis for further research in soil microbiology and for attempts at maintaining and improving the useful properties and productivity of the soil as a renewable natural resource as discussed by the authors.
TL;DR: The theoretical and experimental study of the magnetic moments of Nd3+ ions in aluminium and gallium garnets respectively was performed in this article, and it was concluded that the crystal field effects are not sufficient to explain the whole magnitude of the anisotropy of magnetization in Nd-Sc-Fe garnet observed in our earlier work.
Abstract: The theoretical and experimental study of the magnetic moments of Nd3+ ions in aluminium and gallium garnets respectively was performed. The calculation of the field dependence of the magnetic moment of Nd3+ in YAG, based on the complete set of 9 crystal field parameters determined from the analysis of the optical spectra, gives at 4·2 K the anisotropy of the magnetic moment of about 10%. The magnetization curves of Nd3Ga5O12 were measured in static fields up to 46 kOe and found to be anisotropic and lying very near to the theoretical curves for Nd: YAG. The pulse field measurements up to 210 kOe provided no reliable results probably owing to the strong magnetocaloric effect. It is concluded that the crystal field effects are not sufficient to explain the whole magnitude of the anisotropy of magnetization in Nd-Sc-Fe garnet observed in our earlier work.
TL;DR: In this article, the relation between strength and porosity was derived and compared with commonly used empirical relations, assuming that the distribution of particles in the porous body is random, and compared to the empirical relations.
Abstract: Many porous bodies form by the growth and joining of individual solid particles into a network-like structure. Assuming that the distribution of particles in the porous body is random, the relation between strength and porosity was derived and compared with commonly used empirical relations.
TL;DR: In this article, the equation of motion for radial oscillations of bubble domains is formulated, linearized, and solved for a bubble interacting with a general environment, for the cases of one bubble in finite plate and a close packed hexagonal array of bubbles special solutions are presented and discussed.
Abstract: The equation of motion for radial oscillations of bubble domains is formulated, linearized, and solved for a bubble interacting with a general environment. For the cases of one bubble in finite plate and a close packed hexagonal array of bubbles special solutions are presented and discussed. Domain wall resonance effects in such bubble systems can be expected even in materials with rather high values of the wall motion damping constant.
Es werden die Bewegungsgleichungen fur radiale Schwingungen von Bubble-Domanen in Wechselwirkung mit einer allgemeinen Umgebung formuliert, linearisiert und gelost. Fur den Fall einer Bubble in einem begrenzten Plattchen und fur ein dichtgepacktes hexagonales Bubblegitter werden spezielle Losungen angegeben und diskutiert. In derartigen Bubblesystemen kann man Wandresonanzeffekte auch in Werkstoffen mit ziemlich hoher Wanddampfung erwarten.
TL;DR: In this paper, it is shown that part of the presumed Upper Proterozoic in Bohemia could well belong to the Lower Paleozoic (Cambrian) and a comparison is made with assemblages from the Middle Cambrian (Acadian) of Bohemia.
Journal Article•
TL;DR: Inner surface of the trabecular meshwork in eighteen human eyes between 5 and 80 years of age were studied by means of the wet replica technique.
Abstract: Inner surface of the trabecular meshwork in eighteen human eyes between 5 and 80 years of age were studied by means of the wet replica technique. Three different kinds of age changes can occur separately and differ not only with respect to age, but also within the same age group, and even within the same eye. They all begin mostly in small, circumscribed areas at the comeal margin and from there they can eventually encroach upon the whole circumference of the anterior chamber angle. The replica technique has definite advantages for this type of investigation.
TL;DR: In this article, a DTA apparatus has been developed which can operate up to pressures of 500 atm and temperatures of 500°C and a coated thermocouple (thermocoax) is used for the measurement of temperature differences, for the dehydration of gypsum, hydration of cement paste and hydrothermal synthesis of calcium silicates hydrates.
TL;DR: In this paper, a method that enables precise measurements of birefringence by employing the light phase modulator (cubic electro-optic crystal) to improve the accuracy of the measurements performed with Senarmont compensators is described.
Abstract: The paper contains a description and discussion of a method that enables precise measurements of birefringence by employing the light phase modulator (cubic electro-optic crystal) to improve the accuracy of the measurements performed with Senarmont compensators. In principle, this method allows to attain the same limiting accuracies as those attained by apparatuses using the polarization plane modulators (Faraday cells). The main advantage of the new method is its simplicity. In a practical realization, relative accuracy of ±001° in the determination of the phase shiftδ of measured sample was reached.
TL;DR: In this article, the specific retention volumes, Vg, of the C1-C5 fatty acids and water have been measured and some thermodynamic quantities (ΔH) have been calculated, providing information on the nature and the magnitude of the sorbate-sorbent interactions.
TL;DR: It was concluded that the 1–4 sequence Ser‐Tyr‐Ser‐Met, regardless of whether the N‐terminal is free or blocked, can potentiate the natriuretic action of vasopressin.
Abstract: . Because a) a mixture of alpha-melanotropin (MSH) and corticotropin (1–13)-tridecapeptide (1–13 ACTH) has apparently been isolated from natriuretic fractions of posterior pituitary which also contained arginine-vasopressin, and b) the natriuretic activity of the isolated fraction was greater than that of any of the above three peptides (synthetic) given separately, possible interaction was studied with model substances in the chloralosed cat preparation. It was found that with both alpha-MSH and lysine-vasopressin, extracted samples were more natriuretic than synthetic samples despite an equivalence of pressor activities. When combined with arginine-vasopressin in one injectate, synthetic alpha-MSH, 1–4 ACTH, 1–13 ACTH-amide and 1–18 ACTH all showed potentiation of natriuretic activities with no effect on pressor activity. This effect was not shown by synthetic 4–10 ACTH and 5–18 ACTH, or by extracted alpha-MSH. It was concluded that the 1–4 sequence Ser-Tyr-Ser-Met, regardless of whether the N-terminal is free or blocked, can potentiate the natriuretic action of vasopressin.
01 Jan 1974-Zentralblatt für Bakteriologie, Parasitenkunde, Infektionskrankheiten und Hygiene. Zweite Naturwissenschaftliche Abteilung: Allgemeine, Landwirtschaftliche und Technische Mikrobiologie
TL;DR: Improved methods for detection of morphological changes induced in fungi by antibiotics are described, which standardize the cultivation conditions and sampling, and thus allow to detect even minimal morphological differences.
01 Jan 1974
TL;DR: The human keratinocytes of the outermost granular cell layer were studied by means of conventional electron microscopic procedures to provide more information on the nuclear dense inclusions.
Abstract: The human keratinocytes of the outermost granular cell layer were studied by means of conventional electron microscopic procedures to provide more information on the nuclear dense inclusions. The morphology of these inclusions was very variable in respect to their size and density depending on the fixation of specimens for the electron microscopy. The less mature keratinocytes usually contained small inclusion bodies. More mature cells mostly possessed large inclusions. In addition, the cytoplasm of these cells frequently contained similar inclusions. However, cytoplasmic inclusions were absent in keratinocytes lacking similar structures in their nuclei.
TL;DR: In this article, the Boltzmann equation was applied to the electron gas in the positive column in a helium-metal vapour mixture discharge, taking into account elastic and inelastic collisions of electrons with helium and metal atoms as well as mutual impacts of electrons.
Abstract: The Boltzmann equation was applied to the electron gas in the positive column in a helium-metal vapour mixture discharge. The problem was solved both numerically and approximately taking into account elastic and inelastic collisions of electrons with helium and metal atoms as well as mutual impacts of electrons. Separately the influence of Zn, Cd and Hg atoms on the mean kinetic energy, the mobility (drift velocity) and the diffusion of the electrons was investigated. Approximative relations for those quantities were found and a physical interpretation of their behaviour is given.