Showing papers by "Bulgarian Academy of Sciences published in 1978"
113 citations
TL;DR: Visual localization phenomena were studied before, during, and after a saccade, and a possible theory to deal with the data was suggested by modifying the algebra of outflow-inflow theories.
Abstract: Visual localization phenomena were studied before, during, and after a saccade. Light flashes of 5 and 9 msec duration presented before and during the eye movement were mislocated in the saccade direction, the localization error being a time function. When the 9-msec duration stimulus and saccade did not overlap in time, a stripe was reported, when they did not, the stimulus was perceived as a point. If a long-duration stimulus moved perpendicularly to the saccade direction with the same “sigmoidal” velocity, a curvilinear trace was perceived, regardless of the linear trace of the image on the retina. A stimulus with stabilized retinal image was perceived as a stationary point during the saccade. A possible theory to deal with the data was suggested by modifying the algebra of outflow-inflow theories.
112 citations
TL;DR: In this article, it was shown that the process of photoelectrochemical oxidation of tet-PbO to PbO2 in H2SO4 solution in the potential region leads to the transformation of PbOn into a semiconductor with electrone conductivity.
106 citations
TL;DR: Experiments were made concerning the delay times involved in smooth eye movements in the case of a disappearing target and an alternative point of view is entirely different from the largely accepted “servomotor” theory.
99 citations
85 citations
75 citations
TL;DR: In this article, a structural model on tellurite glasses based on neutron diffraction data was proposed and the coordination scheme of Te was determined and the binding system of the basic coordination polyhedra was establihsed.
Abstract: A structural model on tellurite glasses, based on neutron diffraction data, is proposed. The coordination scheme of Te is determined and the binding system of the basic coordination polyhedra is establihsed. The role of the modifier (Fe2O3) in the glasses is discussed. The atomic density radial distribution function obtained, permits to conclude that the interatomic distances in the region 3.7 to 4.0 A considerably increase at the vitreous state transition.
[Russian Text Ignored].
74 citations
TL;DR: In this article, the invariant subspaces of the reducible EIR are introduced and the differential intertwining operators between partially equivalent EIRs are defined. And the results will be applied elsewhere to the nonpertubative analysis of Euclidean conformal invariant quantum field theory.
54 citations
TL;DR: In this article, the corrosion anodique du plomb decoule en deux etapes, i.e., decoupling dans la masse de loxyde ou bien a son interface avec the solution.
48 citations
TL;DR: The Srednogorie zone of Bulgaria was the site of extensive Late Cretaceous calc-alkalic and shoshonitic magmatism as mentioned in this paper, which is the most similar to our own.
Abstract: The Srednogorie zone of Bulgaria was the site of extensive Late Cretaceous calc-alkalic and shoshonitic magmatism. The calc-alkalic volcanism developed mainly in the central and western parts, whereas shoshonitic volcanism was the predominant magmatic feature of the eastern part. Leucitic basanites, limburgites, and picrites occur in minor amounts in eastern Srednogorie. The shoshonitic volcanic rocks are intermediate to silicic in composition and are characterized by high K 2 O, K 2 O/Na 2 O around unity, high Rb, Sr, and Ba, and low TiO 2 contents. They are associated with calc-alkalic rocks less strongly enriched in K and incompatible elements. Petrographically, the calc-alkalic rocks are characterized by the presence of hydrous mineral phenocrysts that are not present in the shoshonitic rocks. Shoshonitic and calc-alkalic rocks have some common chemical characteristics such as low TiO 2 , lack of absolute iron enrichment, and large overlap in many trace-element abundances. These are considered evidence for a genetic relationship between their primary magmas, which may have undergone different degrees of enrichment in incompatible elements. The eastward increase of K-rich volcanic rocks relative to calc-alkalic rocks in the Srednogorie zone is believed to be related to distension tectonics connected with the opening of the Black Sea.
47 citations
TL;DR: The results of these studies suggest that oleuropein, the valepotratic fraction, carataemon, hyperoside, and peucordin produce a clear-cut coronary dilatory action.
Abstract: Studies were made of the action of biologically active substances isolated from medicinal plants on the coronary circulation under normal conditions and under conditions of induced coronary insufficiency, as well as on models of rhythmic disturbances provoked by different methods. The substances tested were: iridoid Oleuropein isolated from the olive leaves (Olea europaea); valepotriatic fraction Vpt2 isolated for the valerian roots (Valeriana officinalis), all the flavonoids named crataemon and the hyperoside isolated from it, obtained from the flowers and leaves of hawthorn (Crataegus monogina); and all the furocoumarines named peucordin isolated from Peucedanum officinale. The results of these studies suggest that oleuropein, the valepotratic fraction, carataemon, hyperoside, and peucordin produce a clear-cut coronary dilatory action. The coronary flow of a rabbit heart isolated after the method of Langendorf was found to increase by more than 160% by crataemon (2×10-5), hyperoside (1×10-5) and peucordin (2×10-5) and more than 50% by oleuropein and the valepotriatic fraction. This effect of cratemon, hyperoside, and peucordin showed them to be superior to prenylamine. The coronary dilatory effect was also evaluated in experiments on whole organism (cats). It was found that in a dose of 10 mg/kg, peucordin increased the coronary flow by 82% hyperoside by 47%; crataemon, by 37% and the valepotriatic fraction, by 30%. The natural substances tested also eliminated induced pituitrin coronary spasm (experiments on unanaesthetized rabbits). Some of these substances showed a marked antiarrhythmic action, too. Oleuropein was active against BaCl2-induced arrhythmia (in rabbits) and against calcium-induced arrhythmia (in rats); it weakened the aconitine-induced arrhythmia. Crataemon also exerted a clear-cut effect on some kinds of induced arrhythmia. Crataemon and peucordin decrease oxygen utilization in the myocardium.
TL;DR: In this article, the half-life of isomeric nuclei has been determined by in-beam measurements applying the method of delayed γ-γ coincidences as well as by experiments in the radioactive decay with the delay σ-ce coincidences, respectively.
TL;DR: In this paper, the authors derived an equation for the time of appearance of dendrites which accounts for the effect of diffusion and experimentally tested it on a rotating disc electrode under potentiostatic conditions.
Abstract: By means of microscopic measurements on a rotating disc electrode under potentiostatic conditions it is established that the propagation rate of the precursors is constant within the limits of the diffusion layer boundary. The propagation kinetics follow the expression of Diggle, Despic and Bockris [3] if it is assumed that the radii of curvature at the tip of the growing precursorsr increase proportionally with the height of the precursorsy. The overpotential dependence of the ratioy/r is linear and probably reflects the Kelvin relation. At constant diffusion layer thickness the moment of the visual appearance of the dendrites coincides with the transition time on the potentiostaticI-t curves. The average heighty at this moment is equal to the diffusion layer thickness δ. The average rate of growth of precursors is inversely proportional to δ. An equation for the time of appearance of dendrites which accounts for the effect of diffusion is derived and experimentally tested. The effect of lead ions on the time of appearance is discussed in terms of the kinetic equation.
TL;DR: In this paper, the possibility for direct preparation of ionic coal adducts from finely ground low-volatile bituminous coal (89.2% C) and metallic potassium with stirring at 120 °C and a vacuum of 13 mPa was shown.
TL;DR: The arising of saddle splay instability is considered in this paper, where a necessary condition for this condition is that the saddle Splay elastic modulus K exceeds a given critical positive value.
TL;DR: In this paper, an expression for the mean thickness N 99 of vapour-deposited thin films at the moment t 99 of 99% substrate coverage was derived, characterizing the thickness at which thin films reach continuity, decreases with decreasing substrate temperature T and/or increasing deposition rate R.
TL;DR: In this paper, the conformation of the NH-CS-NH grouping in a series of N,N-diarylthioureas some of which possess a marked anti-viral activity is studied using IR spectral data.
TL;DR: The rate of synthesis of total nuclear proteins decreases steadily but the histones show a reproducible pattern of an initial increase in this parameter at a time when DNA synthesis is blocked, indicating that histone synthesis becomes independent of DNA replication during Friend cell differentiation.
Abstract: ERYTHROLEUKAEMIC mouse spleen cells (Friend cells) can undergo erythropoietic differentiation in vitro when cultured in the presence of a variety of different inducers1–6. Untreated Friend cells are arrested at a proerythroblast-like stage of development in the erythropoietic lineage7 and contain little or no globin mRNAs and no haemoglobin. In response to an inducer the cells start transcribing the globin genes, accumulate globin mRNAs and haemoglobin in the cytoplasm3,8 and express morphological and biochemical changes which parallel changes observed during normal in vivo erythropoiesis in the mouse. Dimethyl sulphoxide-induced Friend cells (strain 745 A) show a transient block in the initiation of DNA synthesis which precedes detectable expressions of the differentiated functions9. We report here a G1 phase prolongation in another Friend cell line using another inducer (n-butyrate). We have also characterised the induction process in respect of the capacity of the cells to synthesise and transport proteins to the nucleus. The rate of synthesis of total nuclear proteins decreases steadily but the histones show a reproducible pattern of an initial increase in this parameter at a time when DNA synthesis is blocked, indicating that histone synthesis becomes independent of DNA replication during Friend cell differentiation.
TL;DR: In this article, it was found that the considerable differences observed in IR spectra in the range 900-1250 cm−1 are caused by irregularities of the G conformation of the polymer chain.
Abstract: IR spectra of hexagonal poly(oxymethylene) samples prepared by various polymerization procedures have been studied. The samples were further modified by pressure and by milling in liquid nitrogen. It was found that the considerable differences observed in IR spectra in the range 900–1250 cm−1 are caused by irregularities of the G conformation of the polymer chain. The regularity of the G conformational structure increases by pressing and milling.
TL;DR: It was found that an increased proteolytic activity was present in liver homogenates from carcinogen-fed animals which caused differences between the nonhistone chromosomal proteins of control and carcinogens-treated livers.
Abstract: The chromosomal proteins of rat liver were studied by SDS-gel electrophoresis during the process of nitrosomorpholine-induced hepatocarcinogenesis, in the primary hepatomas thus obtained, and in their metastases. It was found that an increased proteolytic activity was present in liver homogenates from carcinogen-fed animals which caused differences between the nonhistone chromosomal proteins of control and carcinogen-treated livers. These differences disappeared in the presence of the protease inhibitor PMSF. In the primary hepatomas slight quantitative changes were observed: an increased amount of two proteins of 43000 and 63000 daltons molecular weight, respectively, and a decrease in the histone subfraction H 1°. In the metastases both quantitative and qualitative differences were detected: a strong decrease in the protein bands corresponding to the contractile proteins α-tubulin, β-tubulin, and actin; an increased content of the 63000 dalton protein; the appearance of new proteins of approximately 60000, 90000, and 120000 daltons molecular weight, and the complete disappearance of histone H1°.
TL;DR: In this paper, the influence of the contacting electrolyte on the electronic conduction of a system electrolyte/anodic film/metal(+) was studied with Al, Ta, Nb, and Zr, previously anodized under standard conditions.
TL;DR: In this article, the adsorption behavior of polyethers of the polypropyleneglycol (P) type, derivatives of safronic dyes (B); sulpho-organic aliphatic compounds containing the disulphide group -S-S- (DS) and combinations of the three additives (KD) were investigated.
TL;DR: In this article, the authors studied the uranium adsorption on activated carbon from dilute solutions as a function of pH, uranium concentration and ageing time, and they determined the optimum conditions for quantitative adaption of uranium from water solutions: uranium concentration 2.10−4 g/l or less.
Abstract: The uranium adsorption on activated carbon from dilute solutions was studied as a function of pH, uranium concentration and ageing time. Optimum conditions for quantitative adsorption of uranium from water solutions were determined: uranium concentration 2.5.10−4 g/l or less; adsorption must be carried out in fresh prepared solutions with ageing time not more than one hour; pH 7.5–8.5; time for achieving the adsorption equilibrium not less than 20 min. The instrumental neutron activation method was used for the uranium analysis.
TL;DR: In this article, the induction period for the onset of crystallization in poly(ethylene terephthalate) in the presence and absence of small metallic particles was determined in terms of nucleation activity.
Abstract: The induction period for the onset of crystallization was determined in poly(ethylene terephthalate) in the presence and absence of small metallic particles. Two kinds of substrates were used: single microcrystals “transplanted” from the water-soluble inorganic polymer (NaPO3)x and powders of the same metals (Au, Pt, and Ir). The nucleating activity ϕ of the substrates was determined on the basis of classical nucleation theory. Values of ϕ obtained for PET are compared with the corresponding values in the (NaPO3)x melt and with theoretical concepts.
TL;DR: In this article, a general theory of macro-stress in polycrystalline metal layers was developed and the main origin of the stress is the excess of free surface energy (or grain boundary energy) of the crystallites in comparison with the crystal with equilibrium form.
TL;DR: In this paper, optical microscopic observations of the morphology of supermolecular structures grown isothermally from the melt were used to determine the dependance of structural-morphological changes on temperature.
Abstract: Poly(ethylene oxide) fractions with molecular weights in the range from 1.55 × 103 to 1.5 × 105 were studied. The optical microscopic observations of the morphology of supermolecular structures grown isothermally from the melt were used to determine the dependance of structural-morphological changes on temperature. Two morphological transitions were established: (1) a high temperature transition at 49 [Ptilde] 3° C from hedritic structures to positive spherulitoids and (2) a low temperature transition at 38 [Ptilde] 2° C from positive spherulitoids to negative spherulites. It is supposed that the transition from hedrites to positive spherulitoids proceeds through a transition from b-axis-oriented lamellae with tilted chains to [401] lamellae with chains perpendicular to the lamellar surface.
TL;DR: In this paper, the mechanism of preparation of Co 3 O 4 by thermal decomposition of cobaltous salts (oxalate, nitrate, carbonate) using magnetic methods and thermogravimetry was studied.
TL;DR: In this article, anionic polymerization of methyl methacrylate in THF and toluene at −70° was studied by means of i.r. spectroscopy, and the reaction mixtures show characteristic absorption at 1600-1750 cm−1 caused by the stretching vibrations of the propagating centre as well as by the groups obtained in side reactions (metal splitting, addition to a carbonyl group, cyclization).