Showing papers by "Bulgarian Academy of Sciences published in 1970"
TL;DR: In this paper, the passivation process of the Pb/PbSO 4 electrode was investigated by measuring the potential, capacitance and resistance during galvanostatic anodic polarization and a subsequent open-circuit period.
90 citations
TL;DR: Voluntary saccades of 13° arc are made and temporal thresholds for two kinds of stimuli—horizontal and vertical bands—are obtained and data, that “smearing” of the retinal image plays a definite role are given.
40 citations
TL;DR: The concentration of UDP-glucuronic acid was higher in the liver of rats, rabbits and guinea pigs than in the same tissue of some species of birds, amphibia and fishes; also, the concentration in rat liver, kidney and small intestine was several times lower than that of the same tissues of Guinea pigs.
Abstract: 1. A method for the isolation from animal tissues of UDP-glucuronic acid by one-dimensional paper chromatography is described and its concentrations in some tissues of several species of vertebrates are reported; the incorporation of [32P]-phosphate into UDP-glucuronic acid in vivo was also investigated. 2. The concentration of UDP-glucuronic acid was higher in the liver of rats, rabbits and guinea pigs than in the same tissue of some species of birds, amphibia and fishes; also, the concentration of UDP-glucuronic acid in rat liver, kidney and small intestine was several times lower than that of the same tissues of guinea pigs. 3. The rate of [32P]-phosphate incorporation into UDP-glucuronic acid was very high in rat liver and kidney and almost reached equilibrium with the radioactivity of UDP-glucose 30min after the administration of the [32P]phosphate.
39 citations
TL;DR: In this article, a variation of apparatus for the rapid determination of specific surface areas on the basis of an approximate estimation of point B in the BET theory has been proposed, which enables one to measure minimum surface areas of the order of 0.1 m 2 g.
32 citations
TL;DR: In this article, the distribution of visual suppression during voluntary saccade on different places of the retina was obtained, showing that the fovea centralis is not always the most sensitive part of retina.
28 citations
TL;DR: A linear dependence between the size of the saccade and the percentage has been observed, which gives clear evidence that the simple “smearing” of the retinal image can not be the only cause for the decrease in vision during a voluntary saccades.
27 citations
TL;DR: Theoretically, the peristaltik myogen is a myogener Natur, sie last sich weder durch Atropin noch durch Tetrodotoxin unterdrucken.
Abstract: An Muskelpraparaten aus verschiedenen Regionen des Meerschweinchen-Magens wurde neben der Kraftentwicklung die elektrische Spontanaktivitat gemessen, und zwar a) mit extracellularen Elektroden und b) intracellular mit Hilfe von Mikroelektroden. Funduspraparate besitzen in der Regel eine tonische Aktivitat in Form von regelmasigen schnellen elektrischen Oscillationen mit einer Frequenz um 60/min (Sekunden-Rhythmus), welche die Spikes tragen und so die Kontraktionen triggern. Dieser Grundtonus wird durch langsamere Rhythmen moduliert: einmal durch eine Minuten-Rhythmik, die Periodendauern von 1–3 min aufweist, sowie ferner durch noch langsamere Fluktuationen mit einer Periodendauer bis zu 1 Std (Stunden-Rhythmus). Der im Fundus nur angedeutete peristaltische Grundrhythmus wird nach distal immer starker und erreicht im Antrum seine maximale Auspragung, wahrend Minuten- und Stunden-Rhythmik nach distal hin immer schwacher werden. Die Peristaltik ist an Schwankungen des basalen Membranpotentials gebunden, deren Amplitude in Antrumpraparaten bis zu 35 mV betragt. In den Phasen der Depolarisation werden sekundenrhythmische Oscillationen und Spikes ausgelost. Die Spontanaktivitat ist myogener Natur, sie last sich weder durch Atropin noch durch Tetrodotoxin unterdrucken. Es wird die Theorie aufgestellt, das die Peristaltik myogen ist und im tonischen Funduspol des Magens ihren Ursprung hat. Gliederung und Terminologie der glattmuskularen Spontanrhythmen des Verdauungstraktes werden diskutiert.
25 citations
TL;DR: The electrical conductivity of the blue solution is in the range of 10-5 to 10-6 ohm-1 cm-1 and that of the discolored solution is 10-8 to 10 -9 ohm 1 cm- 1 cm 1.
Abstract: Alkali metals dissolve not only in liquid ammonia but also in ethers, such as tetrahydrofuran (THF), 1.2-dimethoxyethane (DME), and dimethyl ether of diethylene glycol (diglyme), blue solutions being obtained1,2. “Blue” solutions can be obtained only with rigorously purified reagents in full absence of moisture and oxygen, usually at low temperature. They are not very stable systems, especially at room temp., and discoloration begins shortly after the removal of the metal. The concn. of the metal dissolved is as low as 10-4 to 10-3 mole/1. The electrical conductivity of the “blue” solutions is in the range of 10-5 to 10-6 ohm-1 cm-1 and that of the discolored solution is 10-8 to 10-9 ohm-1 cm-1.
Obviously the solvation ability of the solvent plays a very important role in the formation of metal solutions. DAINTON et al.1,3 presented arguments that the predominant species in the “blue” solutions are pairs of electrons (e2) with coupled spins, whereas TUTTLE and WEISSMAN4 observed at -80°C a weak singlet in the ESR spectrum of the potassium solution in DME, and CAFASSO and SUNDHEIM2 revealed a weak ESR signal in a rubidium solution in bis-2-(2-methoxyethoxy) ethyl ether as well as in a frozen potassium solution in DME.
“Blue” alkali metal solutions can be easily obtained in hexamethylphosphoramide but it is not still clear whether they are solutions of alkali metals5 or of anion-radicals of the solvent6.
It was established that potassium solutions in THF and DME initiated polymerization of acrylonitrile (conversion about 4%) and of styrene (conversion up to 100%), but not of methyl methacrylate and acrylamide3.
25 citations
21 citations
TL;DR: Using the approach of Harrison, a general expression which permits to calculate the probability of electron transitions through and over potential barriers in solids for any given energy value is derived as mentioned in this paper.
Abstract: Using the approach of Harrison, a general expression is derived which permits to calculate the probability of electron transitions through and over potential barriers in solids for any given energy value. The conditions at which this expression is valid are specified.
Unter Anwendung des Verfahrens von Harrison gelingt es, einen allgemeinen Ausdruck abzuleiten, der es gestattet, die Ubergangswahrscheinlichkeit des Elektrons durch und uber Potentialschwellen in Festkorpern fur beliebige Energiewerte zu berechnen. Die Gultigkeitsbedingungen dieses Ausdrucks werden bestimmt.
20 citations
TL;DR: In this article, the authors investigated the growth mechanism of α-Na2S2O3 · 5 H2O by means of a specially developed capillary technique and proved a quantitative agreement with the theory of two-dimensional nucleation.
Abstract: The mechanism of crystal growth from undercooled melts is investigated experimentally in α-Na2S2O3 · 5 H2O by means of a specially developed capillary technique. Dislocation-free crystal faces are obtained by continuous growth of a α-Na2S2O3 · 5 H2O single crystal in a capillary or by appropriate annealing. The growth mechanism of such perfect crystal faces can be described by the theory of two-dimensional nucleation. The crystallization mechanism of the same single crystals when damaged intentionally or accidentally is determined by screw dislocations. These two basic growth mechanisms as well as the process of dissolution of α-Na2S2O3 · 5 H2O in its own melt are thoroughly studied on one and the same crystal face. A quantitative agreement with theory is demonstrated.
TL;DR: In this paper, the authors derived expressions for the nucleation rate and the total number of nuclei formed in the system with respect to a linear supersaturation change during the process.
TL;DR: Some of the theoretical bases of the bubbling method (different terms of an equipotential family can be approximately obtained using this method) are considered and a few examples for application are given, showing its efficacy at solving problems from the exploration geophysics.
Abstract: Some of the theoretical bases of the bubbling method (different terms of an equipotential family can be approximately obtained using this method) are considered. A few examples for application of this method are given (a programme for a digital computer is used), showing its efficacy at solving problems from the exploration geophysics.
TL;DR: In this article, the electrical, photoelectric and photopolarization properties of vitreous arsenic sulphide were investigated, and it was shown that this substance is a good photoelectric, and a model of its band structure was suggested.
Abstract: Investigations are described of the electrical, photoelectric and photopolarization properties of vitreous arsenic sulphide, both pure and containing silver and copper impurities. It is shown that this substance is a good photoelectric, and a model of its band structure is suggested.
TL;DR: In this paper, the activation energy of the ionic conduction process in γ-Fe 2 O 3 is 1·39 eV and the temperature dependence of the field coefficient is linear but shows an intercept at zero 1/T.
TL;DR: In this paper, the enhanced electron production rate of solar cosmic rays (CR) in the lower ionosphere is theoretically considered, and formulas for the relativistic and lowenergetic solar CR (polar cap absorption event) are derived at C β cos β θ angular distribution of the penetrating particles.
TL;DR: In this paper, an attempt is made to evaluate quantitatively the influence of non-steady state effects in the kinetics of two-dimensional nucleation on the growth of perfect crystals.
TL;DR: In this paper, a linear correlation between the electronic substituent effects and the value of CO splitting is observed, the latter becoming larger with increasing electron donor properties of the substituted carbonyl groups.
TL;DR: Results show that both actinomycin D and 2,4-dinitrophenol cause a preferential inhibition of rRNA synthesis.
TL;DR: The effect of some orotic acid analogues on the incorporation of 14 C-orotate into uridine and cytidine nucleotides by a soluble rat liver enzyme system was investigated.
TL;DR: In this chapter several new classes of functions are introduced which are characterized by their best-possible approximation by splines.
Abstract: Certain classes of functions are introduced which are characterized by their best-possible approximation by splines
TL;DR: Results indicate that RNA in the ribosomes can be easily attacked at some specific sites probably located at the surface of the particle; the rest of RNA appears relatively protected.
TL;DR: In this paper, the authors studied the time dependence of the adatom concentration at sufficiently low substrate temperatures in the presence of a process of formation and growth of three-dimensional nuclei and showed that after a sufficiently long time the number of nuclei tends to a constant value, which depends linearly on the incidence rate, and on the vapour pressure above the substrate.
TL;DR: It is shown that reversibility depended strongly on the ionization of the amino acid residues lying on the surface of the protein molecule and probably associated in “cluster groups”, and the specific effect of tyrosyl groups on the mechanism of reversibility is discussed.
TL;DR: A computer calculation was performed for the particle scattering factors and relative change of the scattered light by randomly and completely oriented cylindrical particles with greatest dimension not exceeding 3 and axial ratios from 0·1 to 10 as discussed by the authors.
TL;DR: In this paper, it has been established that the dark conduction of isatin]-thiophene]-indophenine and of three polymers in which it is a repeating unit is described by the expression [sgrave] = [ sgrave] exp (Eact/kT).
Abstract: It has been established that the dark conduction of isatin-[thiophene]-indophenine and of three polymers in which it is a repeating unit is described by the expression [sgrave] = [sgrave] exp (Eact/kT). The indophenine repeating units in the polymers are connected with a single bond, an oxygen atom, or a methylene group. The electronic spectra in solution and in the solid state indicate that these bonds between the basic units do not interrupt the conjugation along the chain. There is no correlation between the activation energy calculated from optical data and the thermal activation energy of conduction. The latter is considered as a sum of the energy necessary for the generation of the carriers and the energies needed to overcome the intramolecular and intermolecular potential barriers. The values of the parameters characteristic of the semiconducting properties are determined in the first place by the structure of the polymers as a solid body. Crystallinity tends to improve the electrophysical...
TL;DR: In this article, the increase in intensity of spectral lines of cobalt, nickel and manganese in d.c. arc with applied nonhomogeneous magnetic field and burning in oxygen, nitrogen and argon was investigated.
TL;DR: It is shown that proton relaxation, as well as other spin-label methods, can be highly sensitive for studying small-scale conformational changes in protein molecules.
01 May 1970