Showing papers by "Hungarian Academy of Sciences published in 1968"

Importance of the Electric Properties of Supports in the Carrier Effect

Abstract: It has long been recognized in heterogeneous catalysis that the efficiency of the catalyst can be markedly increased when supported by certain solids of large surface. Although this observation has been applied very fruitfully in the preparation of catalysts with technical importance, the reason for the carrier effect is still not fully understood. In earlier investigations the effect of support was explained mainly by saying that it stabilizes the state of the active component or that it increases the degree of dispersion and the surface area of the catalyst. There were, however, some observations stating that, besides the above-mentioned factors, there is a chemical interaction between the catalyst and the support which may also play an important role in producing the carrier effect. Therefore Adadurov and co-workers [1] have pointed out that, depending on its atomic radius and valence, the carrier polarizes the molecules of the catalyst, thus considerably altering the properties of the latter....

Digitonin reaction in electron microscopy.

Abstract: The ultrastructural localization of cholesterol (3β-hydroxysterols) has been studied by the digitonin reaction adapted to the electron microscope. The reaction was undertaken in the adrenal gland, liver, and seminiferous tubules of adult albino rats. The digitonincholesterol crystals formed in the reaction proved to be an osmiophilous cylindrical structure made up of coaxial lamellae.

Pipecolic acid as an indicator of abnormal protein metabolism in diseased plants

Abstract: During the study of the free amino acid spectrum of diseased rice, soybean, potato and tobacco leaves, an unknown compound was detected, the occurrence of which was correlated with an abnormal physiological condition of the plants or with some disturbance in amino acid or protein metabolism. On chromatograms this substance stains blue following fixation with cupric nitrate. After purification with the aid of bacteria, this ‘blue substance’ was identified as pipecolic acid. Since pipecolic acid could be found in the leaves of rice sprayed with maleic hydrazide, but not in control plants, it would seem that it is a metabolic product of growth inhibition.

Responses of cortical neurones to stimulation of the visual afferent radiations.

Abstract: Extracellular spikes of visual cortical neurones in unanesthetized cats were recorded. The latency after electric stimuli of the optic radiation to the onset of firing of cells with concentric fields, simple receptive fields and complex receptive fields was measured.

On some potassium-like qualities of the thallium ion

Abstract: Thallium ist am isolierten Forschherz und M. rectus abdominis von kaliumahnlicher Wirkung. Es setzt das mit kaliumfreier Losung in Stillstand gebrachte Froschherz in Bewegung, bei erhohter Konzentration fuhrt es zum Herzstillstand. Am rectus-Muskel verursacht Thallium eine Kontraktur. Seine Aktivitat am Froschherz ubertrifft jene von Kalium, wahrend am isolierten rectus-Muskel ihre Aktivitat gleichwertig ist.

Simulation of rhythmic nervous activities. II. Mathematical models for the function of networks with cyclic inhibition.

Abstract: Die in diesem Artikel beschriebenen mathematischen Modelle geben eine allgemeine exakte Behandlung des Verhaltens einfacher Netze, die in den Abschnitten 3.1.1–3.1.8. des Teiles I eingefuhrt wurden. Gerichtete Graphen werden studiert, deren Kanten hemmend wirken und deren Punkte durch eine standige „Hintergrundwirkung” angeregt sind, wobei die Stimulation einen linearen Anstieg des Erregungswertes hervorruft. Die Graphen enthalten keine Schlingen und kein Paar ubereinstimmend gerichteter paralleler Kanten. Eine weitere Beschrankung der Struktur der Graphen wird nicht gefordert. Im Gegenteil, es ist eine wesentliche Annahme, das der Reiz auf jeden Punkt in genau derselben Weise wirkt. — Das im Abschnitt 3 konzipierte Modell beschreibt, wie ein Graph von einem gegebenen Anfangszustand aus funktioniert. Die Zeitpunkte T′0(=0), T′1, T′2,..., die den Beginn einer oder mehreren Hemmungsphasen bezeichnen, heisen Sprungmomente. Sind die Erregungswerte im Sprungmoment T′ k bekannt, so definieren wir das folgende Sprungmoment T′ k +1, ferner bestimmen wir durch die Formeln (3.1) und (3.2) die Erregungswerte, die den Punkten zwischen den Zeitpunkten T′ k und T′ k +1 zugeordnet werden. — Im Abschnitt 4 wird ein anderes mathematisches Modell eingefuhrt. Die virtuellen Sprungmomente T0(=0), T1T2,... werden in der Formel (4.1) definiert, die Matrix (4.2) enthalt alle die zu diesen Zeitpunkten moglichen Werte. Die Formeln (4.6)–(4.10) beschreiben, wie die Mengen der Punkte, die die verschiedenen Werte haben, von Tm zu Tm+1 sich verandern. Feststellung 8 behauptet, das das im Abschnitt 4 enthaltene Modell die wesentlichen Aspekte des Vorganges ausdruckt, der durch das im Abschnitt 3 ausgearbeitete Modell formuliert worden ist.

Application of the extended separated pair theory to the π-electrons of trans-butadiene without zero differential overlap approximation

Abstract: Localized strongly orthogonal geminals are constructed by using the SCF orbitals of Parr and Mulliken. The best geminal product wave function is taken as zeroth order function and second order correction is calculated by the extended separated pair theory. 101.3 % of the total “horizontal” correlation energy is obtained taking the result of the “full” CI calculation as standard. It is found that the contribution of terms neglected in the conventional separated pair theory is very important. The results are compared with those obtained by other variants of the Rayleigh-Schrodinger perturbation theory. As has been expected the result of the extended separated pair theory is superior to that of other perturbation theories discussed in the paper.

Investigation of the Near and Far Ultraviolet Denaturation Difference Spectra of Dehydrogenases

Abstract: 1 We have studied the denaturation difference spectra of glyceraldehyde-3-phosphate dehydrogenase and lactic dehydrogenase in the 270–300 mμ and 220–250 mμ wavelength regions. 2 When hydrogen ion concentration is varied in the range from pH 7 to pH 2, the absorption changes at 230–232 mμ are very similar to those at 291–293 mμ with both dehydrogenases. The pH dependence of the optical rotatory parameters b0 and [mμ]232 follows a very similar pattern. 3 The addition of sodium dodecyl sulfate induces hardly any change in the optical rotatory properties of the two dehydrogenases, while the difference spectra both in the near and in the far ultraviolet region closely resemble the corresponding denaturation difference spectra. 4 The solvent perturbation spectra of aromatic chromophores due to 20% ethylene glycol exhibit a maximum in the far ultraviolet region at about 227 mμ. At this wavelength, the extent of perturbation of tryptophan is 6.3 times greater than that of tyrosine. 5 Calculations based on the far ultraviolet perturbation of aromatic chromophores suggest that the far ultraviolet denaturation difference spectra of the two dehydrogenases may be attributed to changes in the environment of aromatic chromophores, particularly of tryptophan.

On the possible mechanism of X-ray coloration in KCl(Ca) crystals

Abstract: It is established by the authors, that in KCl(Ca) crystals grown OH-free and X-irradiated in the temperature interval between −80°C and room temperature the less stableVKM band is observable beside the stableV2M band in the first so-called fast stage of coloration. (The superscriptM referring to the divalent metal impurity serves to distinguish the bands from the correspondingV2 andVK bands of pure crystals.) The positions of the band-maxima, measured at −180 °C are 222 and 323 nm, respectively. TheVKM centres may be transformed spontaneously intoV2M centres, so they can be considered to be “pre-centres” ofV2M centres. The opposite process can also be brought about by illumination with white light. If the crystal, X-irradiated at room temperature (RT) is illuminated at −180 °C with white light, the transformation ofV2M centres into intermediate centres, denoted byV2,KM, becomes observable. Their absorption band lies at 335 nm. With an increase of temperature theV2,KM centres are transformed intoVKM centres. Based on the works ofHayes andNichols and that ofCrawford andNelson, the authors consider theVKM centre to be a Cl2− molecular ion situated in a vacancy-pair next to a Ca++ ion. Starting from this, and on the basis of experimental results, models are proposed for the structure ofV2M andV2,KM centres and for the coloration mechanism at higher temperatures. The oscillator strengths of theVM1 andV2M bands are determined with the aid of the models.

Histochemical and Electron-Microscopic Studies on the Relation between Dopamine and Dense-Core Vesicles in the Neurons of Anodonta Cygnea L.

Abstract: On the basis of data from the literature and our own investigations I should like to sum up some properties of the neurons of Anodonta cygnea: 1. Falck’s method (Falck 1962) gives green fluorescence in the majority of axons and in several nerve cells, and this, as made evident by analyses, originates predominantly from dopamine (Dahl et al. 1962, 1966; Zs.-Nagy 1967a). The dopamine can be depleted from the axons with reserpine. Three to four hours after reserpine treatment, practically no green fluorescence remains in the neuropile of the cerebral ganglion. Within 12 h, all cells produce green fluorescence in the cerebral ganglia, which intensifies for 2–3 days; from the second day, more and more green fluorescence is found in the axons as well (Zs.-Nagy 1967a). 2. The second property of the neurons is that the majority of axons and several cells give a specific positivity with Sterba’s pseudoisocyanine fluorescence method (Sterba 1961) (Zs.-Nagy 1965). This method, according to Sterba (1964), indicates the carrier protein of the elementary neurosecretory granules.

On schwinger’s angular-momentum calculus and the dirac bracket

Abstract: It is shown that canonical quantization of the rigid rotator, according to the procedure proposed by Dirac for systems subject to constraints, naturally leads to Schwinger’s representation of angular momentum. The de Sitter dynamical groupSO3,2 serves as a framework of the treatment.

APPLICABILITY OF THE STATISTICAL MODEL FOR EXPLAINING THE RATIO OF THE (n,n') TO (n,2n) CROSS SECTIONS.

Abstract: The cross sections for the reactions Tl203(n, 2n)Tl202, Hg204(n, 2n)Hg203, Pb204(n, 2n)Pb203m Y89(n, n′)Y89m , Zr91(n, 2n)+Zr90(n, n′)Zr90m , Au197(n, n′)Au197m , and Pb208(n, 2n)+Pb207(n, n′)Pb207m have been measured at neutron energy 15±0,3 MeV, the results are 1680±210, 2230±300, 860±180, 594±130, 820±200, 280±64, and 1340±174 mb respectively. The cross section ratios of (n, n′) to (n, 2n) reactions are considerably higher than the values predicted by the statistical model. Features of (n, 2n) reactions are in agreement with evaporation mechanism, so the most probable explanation of these disagreements is the deviation of the actual spectrum from the evaporation spectrum supposed in the calculations. According to the present results, the competition of inelastic scattering can be important in the case of the heaviest elements too, so theWeisskopf assumptions are not applicable for nuclei with relatively low neutron excess. For the interpretation of theN−Z dependence of (n, 2n) reactions it is necessary to investigate the mechanism of the competing (n, n′) processes.

Correlation between noradrenaline content of the brain and the number of granular vesicles in rat hypothalamus during Nialamid administration.

Abstract: The fine structure of ventromedial hypothalamic nucleus was studied in the rat with the electron microscope under circumstances of elevated brain monoamine level following treatment with a monoamine oxidase inhibitor Nialamid. The number of granular vesicles (size in diameter 450–1100 A) in synaptic terminals increased after Nialamid treatment significantly, while their size did not change; the number of agranular vesicles remained unchanged. The time courses of the increase of granular vesicles and elevation of brain noradrenaline content were approximately parallel. It is inferred that the granular vesicles of size 450 to 1100 A may possibly be the storage sites of noradrenaline.

Theory of zero bias anomalies due to paramagnetic impurities

Abstract: The method developed by one of the authors is generalized to include paramagnetic impurities in order to explain zero bias tunneling anomalies. The self-energy of the electrons is supposed to be a local function in space; nonlocal or assisted tunneling effects are beyond the scope of the present theory. The tunneling current is expressed in terms of the local density of states at the barrier which in turn is given in terms of the life-time of the conduction electrons. The change of the local density of states depends on the positions of the impurities relative to the metal-oxide interface. This dependence is thoroughly investigated.

Apparatus for intensified contacting of plural fluids

Abstract: Different fluids are fed to equipment having at least two chambers separated by a wall having fine perforations, further preferably also separated spaces. The operation is effected by contacting these streams of different components through the partition wall. Liquids are preferably transformed into foams and solids fluidized during the process.