Showing papers by "Charles University in Prague published in 1974"
107 citations
TL;DR: In this article, the dependence of the forming process and of the voltage-controlled negative resistance (VCNR) on the temperature and pressure of an ambient gas (particularly O 2 ) have been studied in Al-Al 2 O 3 -Au sandwich structures.
63 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 effect of Mg, Si, In and Cd solute atoms on the critical resolved shear stress of single crystals has been studied in the “plateau” region in order to complete data on the solid solution hardening of Cu base alloys.
Abstract: The effect of Mg, Si, In and Cd solute atoms on the critical resolved shear stress of Cu single crystals has been studied in the “plateau” region in order to complete data on the solid solution hardening of Cu base alloys. Labusch's equation is obeyed both for the concentration dependences and for the dependence of dτp/dc2/3 one4/3. Edge dislocation/ solute atoms interaction dominates in Cu as in Au and Ag base alloys.
53 citations
TL;DR: A new separation technique has been developed combining the principles of a affinity chromatography and electrophoresis for the separation of phytohemagglutinins from the plant protein mixtures using O-glycosyl polyacrylamide derivatives as affinity gels.
51 citations
TL;DR: The anti-H specific hemagglutinin has been isolated from the seeds of Ulex europaeus L. by saline extraction, (NH4)2SO4 precipitation and affinity chromatography of the active protein fraction on an O-α-l-fucosyl polyacrylamide adsorbent as discussed by the authors.
46 citations
TL;DR: In this article, the main optical, dark and photoconductivity, photo-emf, and photoemission characteristics for thin-layers of pentacene (Pc) crystals were studied.
Abstract: The main optical, dark and photoconductivity, photo-emf, and photoemission characteristics are studied for thin-layers of pentacene (Pc) crystals. It is shown that in the h = = 2.2 to 4.0 eV spectral region intrinsic photogeneration is dominant in Pc crystals, presumably proceeding via an autoionization mechanisms with a threshold value Ec = = (2.20 ± 0.05) eV. Whereas in the hvv = 1.4 to 2.2 eV spectral region an exciton photogeneration mechanism, namely, generation of excess charge carriers through triplet exciton-trapped hole interaction, seems most probably. The energy level spectra of neutral and ionized states of the Pc crystal are determined. The Pc crystal ionization energy Ic equals to (5.07 ± 0.05) eV; the forbidden energy gap ΔE0 = (2.20 ± 0.05) eV; the intrinsic dark conductivity activation energy E = ΔE0/2 = (1.15 ± 0.15) eV. The electron affinity Ac of the Pc crystal, determined by three independent methods equals to (2.87 ± 0.10) eV, (2.70 ± 0.15) eV, or (2.73 ± 0.2) eV, respectively. The characteristic energies of the quasi-continuous trap distribution for vacuum evaporated thin Pc crystals layers are kTc = 0.12 eV in an exponential approximation and ± = 0.28 eV in a Gaussian one as determined from SCLC measurements.
[Russian Text Ignored].
43 citations
TL;DR: In this article, the existence of Frechet smooth norms in weakly compactly generated (WCG) Banach spaces is shown to be hereditary and the property of having a shrinking Markusevic basis is hereditary.
38 citations
TL;DR: periods of the spring depression may be followed by the maxima of either Aphanizomenon or Chlorococcales, with concentrations of chlorophyll increasing to 100 μg/l and more, but all the mechanisms responsible for the transition are not yet fully understood.
Abstract: At the fish ponds under study the authors defined several types of plankton which have been frequently found during the season (April – October). These types are: Early-spring maximum of phytoplankton, Depression of phytoplankton, Bloom of Aphanizomenon, Maximum of Chlorococcales.
The periods of “depression” seem to be typical for the managed carp ponds in the spring. They are characterized by the low density of rapidly reproducing algal populations (e. g. Cryptomonas) and by the dense populations of large cladocerans of the genus Daphnia. Chlorophyll in phytoplankton is less than 5μg/l, transparency is higher than 2 meters.
Periods of the spring depression may be followed by the maxima of either Aphanizomenon or Chlorococcales, with concentrations of chlorophyll increasing to 100 μg/l and more. The change from the phase of “depression” to the “maximum of Chlorococcales” is accompanied by decrease in numbers of Daphnia and increase in numbers of the small cladoceran species, but all the mechanisms responsible for the transition are not yet fully understood.
34 citations
TL;DR: A very low hemagglutinating activity is associated only with the heavy subunit; the light subunit is inactive and both subunits contain serine, as the C-terminal amino acid.
28 citations
TL;DR: In this paper, a conductivity sensor was constructed which can be incorporated into instruments for capillary isotachophoresis and the appropriate electronic equipment was developed using the perspective inland component base.
TL;DR: The normal male phenotypes in all three adult translocation carriers support the hypothesis that the locus for the male determining factor is on the short arm of the chromosome Y.
Abstract: The Robertsonian translocation 45,X,t(Y;15q) was detected in four generations of male progeny. The karyotypes were studied by G-, Q-, and C-banding techniques. The chromosome Y involved in this translocation was of a “short”, “nonfluorescent” variant. The normal male phenotypes in all three adult translocation carriers (the great grandfather, the grandfather, and the father) support the hypothesis that the locus for the male determining factor is on the short arm of the chromosome Y.
TL;DR: The existence of subunits in the molecules of the two pea isophytohemagglutinins was demonstrated by sodium dodecylsulfate polyacrylamide gel electrophoresis, gel filtration and ultracentrifugation in concentrated guanidine · HCl solutions.
TL;DR: The maximum concentration of ethanol precedes the peak of enzyme activity, which is higher big more than one order of magnitude as compared to the amount of lactate, in the case of alcohol dehydrogenases.
Abstract: Lactate as well as ethanol is formed in seeds of soybean, maize, pea, bean, lentil and broad-bean in the course of germination during the so-called natural anaerobiosis. After 0 to 30 h of germination a concentration peak of lactate appears. Maximum in ethanol content is found after 40 h. The amount of ethanol is higher big more than one order of magnitude as compared to the amount of lactate. Both products of anaerobiosis occur in germinating seeds irrespective of the type of reserve substances.
TL;DR: In this paper, the performance of the lanthanum trifluoride electrode in solutions of various acidities, and the surface properties of the LaF 3 crystals in these solutions, have been studied potentiometrically and with the help of x-ray powder patterns, infrared spectrometry and measurement of the β-activity in 3 H-labelled systems.
TL;DR: In this paper, the reflection and transmission coeficients of plane elastic waves for a transition layer were derived from the delta matrices and the 3 × 3 subdeterminants of these matrices were used to derive the transmission coefficients.
Abstract: Formulae are derived for the reflection and transmission coeficients of plane elastic waves for a transition layer. Haskell's technique and the so-called delta matrices[5, 7] are used for this purpose. No problems are encountered in deriving the reflections and transmission coefficients from Haskell's matrices[3]. However, in some cases Haskell's matrices do not guarantee the accuracy required. For this reason attention is mainly devoted to deriving the reflection and transmission coefficients from the delta matrices. In deriving the transmission coefficients use is made of the fact that some3×3 subdeterminants of the delta matrices are squares of the3×3 subdeterminants of Haskell's matrices.
TL;DR: Two phytohemagglutinins isolated from normal saline extract of scarlet runner seeds show non specific agglutinating activity towards all ABO types of human erythrocytes and are shown to be homogeneous on starch and polyacrylamide gels as well as on cellulose acetate strips at different pH values and by thin-layer gel filtration on Sephadex.
TL;DR: In this paper, ten new species of Trichobius were described from the Neotropical Region: T. intermedius (Dominican Republic, Haiti, Bahama Islands, Cuba, Jamaica, Puerto Rico, Virgin Islands, Lesser Antilles, Mexico, Guatemala, Honduras, and El Salvador); T. neotropicus (Dominica and Cuba); T. wenzeli (Cuba); t. cernyi (Cernyi), T. macroti (Bahama Islands); T., robynae (Puerto Rico); and
Abstract: Ten new species of Trichobius are described from the Neotropical Region: T . intermedius (Dominican Republic, Haiti, Bahama Islands, Cuba, Jamaica, Puerto Rico, Virgin Islands, Lesser Antilles, Mexico, Guatemala, Honduras, and El Salvador); T . neotropicus (Dominican Republic); T . cognatus (Dominica and Cuba); T . wenzeli (Cuba); T . dusbabeki (Cuba); T . cernyi (Cuba); T . frequens (Cuba, Dominican Republic, and Jamaica); T . macroti (Cuba and Bahama Islands); T . robynae (Puerto Rico); and T . dominicanus (Dominican Republic).
TL;DR: In this article, the authors synthesized and characterized the pentavalent tungsten with EDTA as salts of the complex anion, [W2O4Y]2−.
TL;DR: In this paper, the effect of the concentration and composition of the electrolyte, pH and age of the solution on polyethylene's adsorption was analyzed and compared with its zeta potential.
Abstract: Adsorption of trace amounts of cations (Ba2−), molecules (Hg(OH)2) and colloids (Fe(OH)3) on polyethylene from aqueous solutions has been studied as a function of the concentration and composition of the electrolyte, pH and age of the solution. The results were analysed and compared with the effect of these factors on zeta potential of polyethylene. It has been concluded that the negative zeta potential indicates that cations can be adsorbed in the outer part of the surface double layer, but the degree of the adsorption is not simply proportional to the zeta potential. Macroconcentrations of electrolytes affect substantially the sorption capacity of polyethylene for cations. Adsorption of molecules and colloids on polyethylene has no direct relation to its zeta potential. The adsorption is mostly enhanced by the addition of an electrolyte, but higher concentrations of the electrolyte may suppress it again. The most probable explanation of the electrolyte effect is the change of the properties of the interface polyethylene-solution or the coagulation of colloids.
TL;DR: In this article, the increase of the critical resolved shear stress of cadmium single crystals by addition of silver has been investigated in the temperature range of 77 K to 199 K, wherec is the atomic concentration of silver as solute, and it decreases with increasing temperature.
Abstract: The increase of the critical resolved shear stress of cadmium single crystals by addition of silver has been investigated in the temperature range of 77 K to 199 K. At all temperatures the critical resolved shear stress increases withc2/3, wherec is the atomic concentration of silver as solute, and it decreases with increasing temperature. The concentration dependence of the critical resolved shear stress is explained according to the theory ofLabusch (phys. stat. sol.41 (1970), 659).
TL;DR: In this paper, single crystals of CdCr2Se4 were prepared by crystallization of polycrystalline material from the melt of cadmium chloride and by synthesis from anhydrous CrCl3 and CdSe.
Abstract: Single crystals of CdCr2Se4 were prepared by crystallization of polycrystalline material from the melt of cadmium chloride and by synthesis from anhydrous CrCl3 and CdSe. Basic optical and transport properties were measured on the crystals. The results are compared with the available literature data and a brief survey of existing interpretation is given.
TL;DR: In this article, a dynamic generator for the separation of carrier-free224Ra is described, where the mother224Ra was extracted on the top of the column with di-(2-ethylhexyl)phosphoric acid on hydrophobized Chromosorb W DMCS.
Abstract: The construction of a dynamic generator for the separation of carrier-free224Ra is described. The mother228Th was extracted on the top of the column with di-(2-ethylhexyl)phosphoric acid on hydrophobized Chromosorb W DMCS. The function of the generator was checked during 6 months by measuring the decontamination of224Ra from228Th. Simultaneously the yield of224Ra was determined as a function of the HCl concentration and of the means of milking. The best results were obtained with 0.01–0.1M HCl; the yield was about 75% of the theoretical value, and the224Ra contained less than 0.01% of228Th.
TL;DR: It was possible to reveal the activity of hetero-β-galactosidase in sections of the rabbit and monkey intestine with phenazonium methosulfate as oxidation agent and nitro BT enhanced the coloration both in zymograms and in sections.
Abstract: The histochemical demonstration of hetero-β-galactosidase (glucosidase) has been attempted in sections and zymograms of rabbit, monkey and human intestine and of rat kidney.
TL;DR: The morphogenesis of muscles of the forearm and hand was studied in embryonic limbs of the axolotl (Ambystoma mexicanum) and compared with the course of morphogenesis in the regenerating limb of adults as discussed by the authors.
Abstract: The morphogenesis of muscles of the forearm and hand was studied in embryonic limbs of the axolotl (Ambystoma mexicanum) and compared with the course of morphogenesis in the regenerating limb of adults. The first part of the paper describes the morphogenesis of muscles ontogenetic development. The course of development, from the stage of muscle blastemas through that of the independent muscle anlagen is described for each muscle. The separation of muscle anlagen and their differentiation forms a prominent proximodistal gradient. At the same time there is a clear radioulnar gradient in the formation of muscle anlagen. Phylogenetically, this radioulnar gradient is restricted to the developing limb of Urodeles. In the second part of the paper, the morphogenesis of muscles is described in the regenerating limb. The major features in regeneration recapitulate those in the embryonic limb. Proximodistal and radioulnar gradients of development are also present in the regenerating limb. This structural similarity in development supports the viewpoint that the regeneration blastema is an integrated morphogenetic unit in which muscles differentiate according to the same genetic plan as they do in the embryo. There are some differences, however, between the regenerating and embryonic limb. The regenerating limb is larger, its muscle blastemas are also larger from the beginning, and the regenerating limb has a relatively greater amount of mesenchymal cells, which are not closely integrated into the muscle or skeletal anlagen.
TL;DR: In this article, the adsorption isotherms of benzene were measured on Porasils that were thermally pre-treated from 100° to 1000° and their specific surface areas were calculated.
TL;DR: In this paper, the orientation distributions of crystallites determined by measurements of 002 reflexions on texture goniometer can be described by simple analytical expressions and corrections for preferred orientation applied to measurements on powder diffractometer enable determination of Debye characteristic temperature from the dependence of intensities on diffraction angle.
Abstract: Cylindrico-symmetrical needle-type texture has been observed in powder samples of magnesium and magnesium-cadmium alloys. Orientation distributions of crystallites determined by measurements of 002 reflexions on texture goniometer can be described by simple analytical expressions. Corrections for preferred orientation applied to measurements on powder diffractometer enable determination of Debye characteristic temperature≡ from the dependence of intensities on diffraction angle. The values of≡ determined after correction from samples with preferred orientation are in agreement with the value of randomly oriented sample.
TL;DR: The purpose of the present communication is to describe ultrastructural fea tures of endocrine cells found in the gastric and intestinal mucosa of the dog.
Abstract: The chromaffin cells of the gastrointestinal mucosa were described for the first time by Heidenhain (1870) in the gastric mucosa of the rabbit and dog. Subse quently, the chromaffin cells were found in the gastrointestinal tract of various animal species and they were designated by the names of their discoverers (Heiden hain cells, Kultschitski cells, Schmidt cells, Feyrter cells). In addition, these cells were also designated as the \"enterochromaffin cells\" (EC). It was not until 1952 that Erspamer and Asero identified the chromaffin substance of the secretory granules of the EC cells as 5-hydroxytryptamine (5-HT), which is a specific product of these cells. The existence of other types of endocrine cells of the gastrointestinal tract was first mentioned by Kull (1913), who found the intestinal mucosa to contain non -chromaffin cells with small acidophilic granules, and by Erspamer (1939), who discovered non-argentaffin argyrophil cells in the gastrointestinal tract. Further differentiation of individual types of the endocrine cells of the gast rointestinal mucosa has become possible by the development of electron microscopic techniques (Toner 1964, Solcia et al. 1967, Orci et al. 1968). The system of endo crine cells has gradually been mapped in the gastrointestinal mucosa of the rat, cat, rabbit and man (Forssmann et al. 1969, Vassallo et al. 1969, Capella et al. 1969, Pearse et al. 1970, Vassallo et al. 1971, Nabeyama et al. 1971). In addition to serotonin, which is a well-known product of the EC cells, gastrin, secretin, cholecystokinin-pancreozymin, glucagon-like substance and enterogastrone were established as the hormonal products of different parts of the gastrointestinal mucosa (Gregory and Tracy 1964, Jorpes and Mutt 1961, Sutherland et al. 1949, Unger et al. 1966, Brown et al. 1969). The purpose of the present communication is to describe ultrastructural fea tures of endocrine cells found in the gastric and intestinal mucosa of the dog.