Showing papers by "Bulgarian Academy of Sciences published in 1992"
01 Jan 1992
TL;DR: It is proved that the basic phenomenon is sequences of lateral fusions of smaller vesicles induced by the applied AC electric field.
Abstract: We suggest a method for preparation of large (∼ 15 ÷ 70 μm in diameter), unilamellar, fluctuating, isolated vesicles, allowing us to perform routine measurements of membrane bending elasticity modulus k c by image analysis of thermal fluctuations. The method is based on the effects of AC electric fields on the lipid swelling and liposome formation. We have observed a monotonous decrease of k c for egg phosphatidylcholine (EPC) vesicles from (0.66 ± 0.06) · 10−19 J for 1 day to (0.45 ± 0.05) · 10−19 J for 13 days after vesicle formation. The lipid mixture Chol/PC 37:63 mol/mol led to k c = (1.06 ± 0.15) · 10−19 J, and PE/PC 25:75 mol/mol — to (0.72 ± 0.06) · 10−19 J. — The mechanism of vesicle formation is discussed. It proved that the basic phenomenon is sequences of lateral fusions of smaller vesicles induced by the applied AC electric field.
751 citations
TL;DR: In this paper, the number of light neutrino species is found to be Nv=3.30% CL with the constraints of the standard electroweak model, which rules out the possibility of a fourth type of LN at 98% CL.
234 citations
TL;DR: The main objective of this survey is to study convergence properties of difference methods applied to differential inclusions to present a number of results scattered in the literature.
Abstract: The main objective of this survey is to study convergence properties of difference methods applied to differential inclusions. It presents, in a unified way, a number of results scattered in the li...
201 citations
TL;DR: The foam bilayer is used as a model for investigating short-range forces in biological structures, the interaction between membranes and cell fusion, and a clinical diagnostic method is developed for assessment of the human foetal lung maturity.
146 citations
TL;DR: In this paper, the kinetics of polyaniline were studied under potentiostatic conditions on gold and platinum microelectrodes, and two different stages of growth were observed, the first corresponding to the formation of a compact layer with average thickness of about 200 nm, the second corresponding to growth of a branched structure.
144 citations
TL;DR: The alteration in C1q complement component and total protein synthesis, and also in nitroblue tetrazolium reduction, suggests that macrophage activation makes a major contribution to the capacity of WSD to prevent infections.
135 citations
TL;DR: Theoretical expressions for the supersaturation dependence of the induction time in seeded and unseeded precipitation are derived for different mechanisms of crystallite growth in this article, and a combined analysis is presented, which allows separate determination of the nucleation and growth rates.
132 citations
TL;DR: It was found that the maximal inhibition of viral reproduction was observed when test substances were present in the medium during the whole infectious process.
Abstract: The antiviral activity of six synthetic substances, esters of substituted cinnamic acids, identical with or analogous to some of the constituents of the Et2O fraction of propolis was studied in vitro. One of them, isopentyl ferulate, inhibited significantly the infectious activity of influenza virus A/Hong Kong (H3N2) in vitro and the production of hemagglutinins in ovo. By the use of diverse experimental patterns, it was found that the maximal inhibition of viral reproduction was observed when test substances were present in the medium during the whole infectious process.
132 citations
TL;DR: It is shown that the fuzzy concepts of Positive, Negative and Boundary region of a set, proposed in the paper, coincide with the original definitions if appropriately applied to ordinary rough classfication.
127 citations
TL;DR: Les secretions des bourgeons, apres une breve extraction a l'acetone, ont ete analyses en chromatogrphie sur couche mince et chromatographie liquide haute pression.
Abstract: Des bourgeons de Populus nigra, P italica, P tremula, Betula verrucosa, Aesculus hippocastanum, Alnus glutinosa, Fraxinus excelsior, Salix alba, Prunus padus et Prunus cerasus ainsi que des echantillons de propolis ont ete preleves dans la region de Sofia, Bulgarie. En Mongolie, de la propolis et des bourgeons de Populus suaveolens ont ete recoltes dans la region d'Ulan Bator, les peupliers de cette espece etant les seusl arbres a pousser dans cette region. Les secretions des bourgeons, apres une breve extraction a l'acetone, ont ete analyses en chromatogrphie sur couche mince et chromatographie liquide haute pression. Seules les secretions de bourgeons de Populus nigra, P italica et P tremula ont fourni des phenols semblables a ceux trouves dans le propolis bulgare
127 citations
TL;DR: In this article, an experimental study has been conducted with the aim to investigate and evaluate thermophysical properties of technical grade paraffins appropriate for solar energy storage applications, which involved the kinetics of phase transition and latent heat of phase change, the thermal cycling stability at heating and cooling and specific heat for the temperature range of application.
TL;DR: In this paper, neutral heavy leptons that are isosinglets under the standard SU (2)L gauge group were searched for and no evidence for a signal has been found and the limit Br(NSu0 → vlNl) < 3 x 10−5 at the 95% CL for mass range from 3 GeV up to Mz.
TL;DR: This paper is an attempt to systematize and solve the problems connected with biomechanical modelling and mathematical investigation of the upper limb, when all muscles acting on the shoulder, elbow and wrist joint are included.
TL;DR: The rate of substrate oxidation increases with increasing α-tocopherol concentration, especially at lower temperatures, but decreases with increasing ferulic acid concentration, which is explained in terms of the participation of antioxidant molecules and radicals in the autoxidation process.
Abstract: Purified lard triacylglycerols have been oxidised at 25, 50, 75 and 100°C in the presence and absence of 0.2–2.0 g kg−1 (0.45–10.3 mmol litre−1) of the antioxidants α-tocopherol and ferulic acid. Increasing the temperature does not influence the effect of ferulic acid on the induction period or the rate of autoxidation, α-tocopherol is more effective at extending the induction period and reducing the rate of autoxidation as the temperature is increased. The rate of substrate oxidation increases with increasing α-tocopherol concentration, especially at lower temperatures, but decreases with increasing ferulic acid concentration. This behaviour is explained in terms of the participation of antioxidant molecules and radicals in the autoxidation process. High-temperature oxidation results can be extrapolated only to room temperature when no change occurs in the antioxidative mechanism.
TL;DR: In this paper, the number of scattering poles in the disc |z|≦r for a large class of compactly supported perturbations (not necessarily selfadjoint) of the Laplacian in ℝ n ≥ 3, odd, was shown to be n(r) ≈Crn+C.
Abstract: Sharp bounds on the numberN(r) of the scattering poles in the disc |z|≦r for a large class of compactly supported perturbations (not necessarily selfadjoint) of the Laplacian in ℝ
n
,n≧3, odd, are obtained. In particular, in the elliptic case the estimateN(r)≦Cr
n+C is proved.
TL;DR: In this paper, it was shown that every module over a commutative homogeneous Koszul algebra has regularity bounded by its regularity over a polynomial ring of which the k-algebra is a homomorphic image.
TL;DR: In this article, the influence of transition metal ions during a thermal process in which electrocatalysts are made from polyacrylonitrile is discussed, and the results concerning the electrocatalitic properties of these materials in self-breathing oxygen electrodes as well as the long-term behaviour and metal dissolution are compared.
TL;DR: Differences in male attraction among the populations studied confirm the existence of significant population variation in the pheromone of A. segetum, and Interpretation of the present results suggests that this variation is more or less continuous in Eurasia and north Africa, while a clearly distinct phersomone type is present in the areas south of the Sahara desert.
Abstract: Selected combinations of (Z)-5-decenyl, (Z)-7-dodecenyl, and (Z)-9-tetradecenyl acetates, the pheromone components of the turnip mothAgrotis Segetum were tested for field attractancy at six, two, and three sites in Europe, Asia, and Africa, respectively. At all of the sites in Eurasia and in northern Africa the ternary mixture of the acetates captured most males, while at the sites south of the Sahara in Africa, (Z)-5-decenyl acetate alone was responsible for attraction. Differences in male attraction among the populations studied confirm the existence of significant population variation in the pheromone ofA. segetum. Interpretation of the present results together with earlier studies suggests that this variation is more or less continuous in Eurasia and north Africa, while a clearly distinct pheromone type is present in the areas south of the Sahara desert.
TL;DR: The results suggest that stimulation of 5-HT1A receptors in the CA1 region of the dorsal hippocampus causes an impairment of spatial discrimination in rats.
TL;DR: A procedure using capillary gas chromatography with an internal standard has been developed for the determination of the main biologically active phenolics of propolis (bee glue): the flavonoid aglycones pinocembrin and galangin, and caffeic acid and its β-phenyl-ethyl ester as discussed by the authors.
TL;DR: In this article, a typical example of the preparation and characterization of polyaniline dispersion is described from a series of experiments, and a typical application of the typical example is described.
TL;DR: The problem of fuzzy optimal control of nonlinear systems is formulated and solved on the basis of fuzzy mathematical programming and the case of multicriteria optimal control with fuzzy objective function and crisp transversality conditions is considered.
TL;DR: In this paper, the processes of formation of the porous structure and the changes taking place on the surface of carbon adsorbents during their preparation by water-vapor pyrolysis from various agricultural byproducts are investigated.
TL;DR: In this paper, the adsorption of Cu2+, Pb2+, Zn2+, and Cd2+ from aqueous solutions at 20°C on oxidized anthracite was studied.
TL;DR: Electron microscopic observations on sections processed under either condition revealed that choline acetyltransferase-positive terminals form synaptic contacts of the symmetrical type with neuropeptide Y-positive somata and proximal dendrites and that cholinergic-positive neurons are contacted by neuropeptic Y- positive terminals.
TL;DR: A new type of instrument, a spectrophotopolarimeter, which can measure simultaneously in real time the spectra of all four Stokes parameters of light, is described.
Abstract: A new type of instrument, a spectrophotopolarimeter, which can measure simultaneously in real time the spectra of all four Stokes parameters of light, is described. The instrument has no moving parts and is extremely simple to calibrate.
TL;DR: The results indicate that muscle length is an important parameter for the propagation velocity of action potentials and for the development of static muscle fatigue.
TL;DR: In this article, the structure of hadronic events from Z ≥ 0 decay is studied by measuring event shape variables, factorial moments, and the energy flow distribution, after correction for detector effects and initial and final state radiation, compared with the predictions of different QCD Monte Carlo programs with optimized parameter values.
Abstract: The structure of hadronic events fromZ
0 decay is studied by measuring event shape variables, factorial moments, and the energy flow distribution. The distributions, after correction for detector effects and initial and final state radiation, are compared with the predictions of different QCD Monte Carlo programs with optimized parameter values. These Monte Carlo programs use either the second order matrix element or the parton shower evolution for the perturbative QCD calculations and use the string, the cluster, or the independent fragmentation model for hadronization. Both parton shower andO(α
2
s
matrix element based models with string fragmentation describe the data well. The predictions of the model based on parton shower and cluster fragmentation are also in good agreement with the data. The model with independent fragmentation gives a poor description of the energy flow distribution. The predicted energy evolutions for the mean values of thrust, sphericity, aplanarity, and charge multiplicity are compared with the data measured at different center-of-mass energies. The parton shower based models with string or cluster fragmentation are found to describe the energy dependences well while the model based on theO(α
2
s
calculation fails to reproduce the energy dependences of these mean values.
TL;DR: In this article, a study of the global event shape variables thrust and heavy jet mass, of energy-energy correlations and of jet multiplicities based on 250 000 hadronic Z 0 decays is presented.