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Showing papers by "Bulgarian Academy of Sciences published in 1996"


Journal ArticleDOI
TL;DR: Removal and reorganization of FN from the material surfaces into extracellular matrixlike structures occurred on GLASS but not on less wettable surfaces, suggesting that this removal/reorganization process may be more sensitive to changes in surface wettability than other parameters of biocompatibility.
Abstract: The ability of human fibroblasts to remove and reorganize fibronectin (FN) bound on material surfaces was studied as a novel feature of material surface biocompatibility. Other traditional parameters of biocompatibility analyzed included cell spreading, clustering of fibronectin receptors into focal adhesions, development of stress fibers, and cell growth. Five different materials with surface wettability ranging from hydrophilic (underwater contact angle 25 degrees) to hydrophobic (underwater contact angle 111 degrees) were used, i.e., clean glass (GLASS), aminopropylsilane (APS), octadecylsilane (ODS), polylactate (PL), and silicone (SI). When cells were cultured on these materials in serum-containing medium, formation of FN receptor-rich focal adhesions and actin stress fibers were more evident on the hydrophilic surfaces (GLASS and APS) compared to the hydrophobic ones (PL, ODS, and SI). Cell growth showed a similar pattern, that is, increased cell proliferation with increasing material surface wettability. Preadsorption of FN on the material surfaces increased subsequent cell spreading and cytoskeletal reorganization on hydrophobic surfaces except SI. Removal and reorganization of FN from the material surfaces into extracellular matrixlike structures occurred on GLASS but not on less wettable surfaces, suggesting that this removal/reorganization process may be more sensitive to changes in surface wettability than other parameters of biocompatibility.

367 citations


Journal ArticleDOI
TL;DR: The in vitro treatment of splenocytes with berberine showed that the anti-SRBC antibody synthesis was influenced in a different manner depending on the time course of its application, and the TEE was most effective in a chronic inflammatory model of adjuvant arthritis.

231 citations


Journal ArticleDOI
TL;DR: A combination of methods, including separation procedures, light microscopy, SEM, TEM, XRD and DTA-TGA methods, were used to characterize the phasemineralogical and chemical composition, microstructural and some genetic phase peculiarities of solid waste products from coal burning as mentioned in this paper.

203 citations


Journal ArticleDOI
TL;DR: The mineralogy of coal and coal ash samples from a wide variety of deposits worldwide has been studied by X-ray diffractometry, light microscopy, SEM, TEM, and DTA-TGA methods as mentioned in this paper.

194 citations


Journal ArticleDOI
TL;DR: The calculated values of the intercellular CO 2 concentration, CO 2 -compensation point and the maximal carboxylating efficiency of ribulose-l,5-bisphosphate car boxylase support the suggestion that biochemical factors are involved in the response of photosynthesis to SA.

193 citations


Journal ArticleDOI
TL;DR: In this article, the water-gas shift reaction (WGSR) was studied on Auα-Fe2O3 catalyst and the results obtained can be explained on the basis of the associative mechanism of the WGSR.
Abstract: The water-gas shift reaction (WGSR) has been studied on Auα-Fe2O3 catalyst. The structure of the samples has been investigated by chemical and physical methods—TEM, X-ray, DTA, FTIR. A high dispersion degree of the gold particles and an increased concentration of the hydroxyl groups on Auα-Fe2O3 has been established in comparison to the pure α-Fe2O3. The results obtained can be explained on the basis of the associative mechanism of the WGSR. The essential aspects are the dissociative adsorption of water on ultrafine gold particles, followed by spillover of active hydroxyl groups onto adjacent sites of the ferric oxide. The formation and decomposition of intermediate species is accompanied by redox transfer Fe3+ Fe2+ in Fe3O4.

181 citations


Journal ArticleDOI
A. Adam1, M. Aguilar-Benitez, J. Alarcon, J. Alberdi  +150 moreInstitutions (13)
TL;DR: The forward-backward muon detector of the L3 experiment is presented in this paper, which consists of 96 self-calibrating drift chambers of a new design enclosing the magnet pole pieces of the l3 solenoid.
Abstract: The forward-backward muon detector of the L3 experiment is presented. Intended to be used for LEP 200 physics, it consists of 96 self-calibrating drift chambers of a new design enclosing the magnet pole pieces of the L3 solenoid. The pole pieces are toroidally magnetized to form two independent analyzing spectrometers. A novel trigger is provided by resistive plate counters attached to the drift chambers. Details about the design, construction and performance of the whole system are given together with results obtained during the 1995 running at LEP.

177 citations


Journal ArticleDOI
TL;DR: It is shown that polarization holography may be used for real-time simultaneous measurement of photoinduced linear and circular birefringence in thin phase polarization holographic gratings recorded with two waves with orthogonal linear polarizations in materials in which illumination with linearly/ Circularly polarized light gives rise to linear/circular bireFringence.
Abstract: We investigate thin phase polarization holographic gratings recorded with two waves with orthogonal linear polarizations in materials in which illumination with linearly/circularly polarized light gives rise to linear/circular birefringence. The theoretical analysis shows that the presence of circular photoanisotropy changes significantly the diffraction characteristics of the gratings. The intensities of the waves diffracted in the +1 and −1 orders of diffraction and their ratio depend substantially on the reconstructing-wave polarization. Experiments with films of side-chain liquid-crystalline azobenzene polyester that is a photoanisotropic material of the considered type confirm the unusual polarization properties. It is shown that polarization holography may be used for real-time simultaneous measurement of photoinduced linear and circular birefringence.

167 citations


Journal ArticleDOI
TL;DR: The results suggest that measurement of the phosphotyrosine activity of cells may be a sensitive parameter for the ability of biomaterials to support the attachment and proliferation of cells.

149 citations


Journal ArticleDOI
TL;DR: In this paper, four labdane-type diterpenic acids and syringaldehyde were isolated and identified from Brazilian propolis, and all the compounds exhibit antibacterial activity.
Abstract: Four labdane-type diterpenic acids and syringaldehyde were isolated and identified from Brazilian propolis. All the compounds exhibit antibacterial activity. The diterpenes, found for the first time in propolis, are typical for some Araucaria species and thus indicate a possible plant source of Brazilian propolis.

132 citations


Journal ArticleDOI
TL;DR: The adsorption and coadsorption of selective catalytic reduction (SCR) reactants and reaction products on CuZSM-5-37 containing 11 wt.-% CuO have been studied by FTIR spectroscopy as discussed by the authors.
Abstract: The adsorption and coadsorption of selective catalytic reduction (SCR) reactants and reaction products on CuZSM-5-37 containing 11 wt.-% CuO have been studied by FTIR spectroscopy. The catalyst surface is characterized by both weak acidity and weak basicity as revealed by testing with probe molecules (CO2, NH3, H2O). NO2 adsorption results in formation of different kinds of nitrates. The same species are formed when NO is coadsorbed with oxygen at 180°C. NO adsorption at ambient temperature also leads to formation of nitrates as well as of Cu2+NO species. In the presence of oxygen the latter are converted according to the scheme: NO → N2O3 → N2O4 → NO2 → NO3. It is concluded that the surface nitrates are important intermediates in the SCR process. They are thermally stable and resistant towards interaction with CO2, N2, O2, and are only slightly affected by H2O and NO. However, they posses a high oxidation ability and are fully reduced by propane at 180°C. It is concluded that one of the most important roles of oxygen in SCR by hydrocarbons is to convert NOx into highly active surface nitrates.

Journal ArticleDOI
TL;DR: In this paper, the interaction of poly(ethylene glycol) Mn = 3000 with copper I and II ions in aqueous-acidic media was studied by investigation of the specific electrical conductivity, optical density and the cyclic voltamperometric curves in Cu+ and Cu2+ solutions.
Abstract: The interaction of poly(ethylene glycol) M n= 3000 with copper I and II ions in aqueous-acidic media was studied by investigation of the specific electrical conductivity, optical density and the cyclic voltamperometric curves in Cu+ and Cu2+ solutions. The results suggest the formation of complexes of the {Cu+(-EO-)3(x − 1)H2O} and {Cu2+(-EO-)4.(y − 1)(H2O)2} types. In the case when {−CH2CH2-O-} n and Cl− are simultaneously present in the copper electrolyte, the possibility of simultaneous complex formation between both copper ions and ethylene oxide units, and copper ions and chloride ions is considered. The strong increase in copper electrodeposition over-potential after the addition of polyethers to the electrolytes containing brighteners is explained by the formation of these complexes.

Journal ArticleDOI
TL;DR: In this paper, the existence of soliton-like solutions of the Maxwell-Dirac system in (3+1)-Minkowski space-time has been proved by a variational method, as critical points of an energy functional.
Abstract: The Maxwell-Dirac system describes the interaction of an electron with its own electromagnetic field. We prove the existence of soliton-like solutions of Maxwell-Dirac in (3+1)-Minkowski space-time. The solutions obtained are regular, stationary in time, and localized in space. They are found by a variational method, as critical points of an energy functional. This functional is strongly indefinite and presents a lack of compactness. We also find soliton-like solutions for the Klein-Gordon-Dirac system, arising in the Yukawa model.

Journal ArticleDOI
TL;DR: The thermal stability of acid-soluble collagen type I from calf skin in salt solutions is studied by high-sensitivity differential scanning calorimetry and variations of the collagen denaturation enthalpy at low and intermediate salt concentrations are consistent with a weak linear increase of theEnthalpy with denaturation temperature.

Journal ArticleDOI
TL;DR: In this article, noncrystalline solids with LiCoC6H5O7·5H2O and (NH4)3LiCo(C 6H 5O7)2 compositions were obtained by ethanol dehydration of concentrated lithium−cobalt citrate solutions.
Abstract: Noncrystalline solids with LiCoC6H5O7·5H2O and (NH4)3LiCo(C6H5O7)2 compositions were obtained by ethanol dehydration of concentrated lithium−cobalt citrate solutions. Electron spectroscopy of solut...

Journal ArticleDOI
TL;DR: In this article, fine CoFe 2 O 4 particles with average size of 50 A have been produced by coprecipitation from Fe(II and Co(II) solutions followed by a low-temperature calcination.

Book ChapterDOI
TL;DR: It has been shown that both interval systems can be used for the computation of tight inner and outer inclusions of ranges of functions and consequently for the development of software for automatic computation of range of functions.
Abstract: We discuss two closely related interval arithmetic systems: i) the system of directed (generalized) intervals studied by E. Kaucher, and ii) the system of normal intervals together with the outer and inner interval operations. A relation between the two systems becomes feasible due to introduction of special notations and a so-called normal form of directed intervals. As an application, it has been shown that both interval systems can be used for the computation of tight inner and outer inclusions of ranges of functions and consequently for the development of software for automatic computation of ranges of functions.

Journal ArticleDOI
TL;DR: A unified analysis of all existing solitary wave solutions of the cubic-quintic nonlinear Schrodinger equation (CQNLSE) is made concretely, considering a monomode step-index optical fiber with third and fifth-order nonlinearities in the anomalous dispersion frequency region.

Journal ArticleDOI
TL;DR: The calculated stability curve shows that Sso7d has, despite of its high melting temperature, an only moderate intrinsic stability, which reaches its maximum at 282 K, and is particularly poorly stabilized at the maximum physiological growth temperature of Sulfolobus solfataricus.

Journal ArticleDOI
01 Oct 1996-Fuel
TL;DR: In this paper, the relationship between coal rank and the mineral and chemical composition of coals and their high-temperature ashes worldwide were studied, and it was found that the occurrence, abundance and origin of mineral matter in coal depends on the coal rank to a certain extent.

Journal ArticleDOI
TL;DR: In this paper, high-temperature solutions of the K2W2O7-KGd1 − xNdx(WO4)2 (KGW:Nd) single crystals were grown.

Journal ArticleDOI
TL;DR: In this paper, the morphological 2D−3D transformations of insoluble supersaturated monolayers of long chain alkanoic acids, and their methyl ester and salt derivatives are studied directly at the air/water interface by means of Brewster angle microscopy.
Abstract: The mechanism of the morphological 2D−3D transformations of insoluble supersaturated monolayers of long chain alkanoic acids, and their methyl ester and salt derivatives is studied directly at the air/water interface by means of Brewster angle microscopy. The phase changes occurring upon continuous overcompression of nonionic and charged monolayers are compared. The relationship between the shape of the monolayer isotherms in the region of the attained maximum surface pressure and the morphological features of the 2D−3D transformations is investigated. The effects of the hydrocarbon chain length variation (C14, C18, C22), hydrophilic head groups ionization, strength of interfacial hydrogen bonding, temperature, and compression rate on the morphology of the 3D phase, separated from the overcompressed monolayers, are monitored. It is found that the interaction of the monolayers with the aqueous subphase (through head groups ionization or hydrogen bonding) has the strongest influence on the morphology of the...

Journal ArticleDOI
TL;DR: In this paper, the authors studied the kinetics of modification of a fluoropolymer coating during its contact with octane, dodecane, and hexadecane via measurement of quasi-static (velocity independent) advancing and receding dynamic contact angles.

Journal ArticleDOI
TL;DR: In this paper, the formation of V2O5 and Bi2O3-rich glasses was investigated by the roller-quenching method and low melting V 2O5- and Bi 2O3 -rich glasses were obtained.
Abstract: Glass formation V2O5Bi2O3Fe2O3 system was investigated by the roller-quenching method and low melting V2O5- and Bi2O3-rich glasses were obtained. Glasses were characterized by X-ray diffraction, differential thermal analysis (DTA), IR and Mossbauer spectroscopy. The glass transformation temperature, Tg, varied between 270 and 442°C, and the crystallization temperature, Tx, was in the range of 342–550°C. Structural models for glasses of the V2O5Bi2O3Fe2O3 system are suggested on the basis of IR and Mossbauer spectral investigations. It was shown that the glasses posses [VO5], [VO4], [BiO6], [FeO6] and [FeO4] groups as basic structural units.

Journal ArticleDOI
TL;DR: In this article, the angular overlap model (AOMM) was used to analyze the absorption spectra and luminescence spectra of a single crystal ion in tetroxo coordination.
Abstract: Polarized single crystal absorption spectra and luminescence spectra of ${\mathrm{Cr}}^{4+}$-doped ${\mathrm{Ca}}_{2}$${\mathrm{GeO}}_{4}$ and ${\mathrm{Mg}}_{2}$${\mathrm{SiO}}_{4}$ are presented and discussed. The absorption spectra are analyzed using the angular overlap model (AOM). The agreement between the experimental and the AOM-calculated energies of the ligand field states is satisfactory. The ligand field parameters 10Dq and B are 8950 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ and 540 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ for ${\mathrm{Ca}}_{2}$${\mathrm{GeO}}_{4}$ and 10 100 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ and 560 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ for ${\mathrm{Mg}}_{2}$${\mathrm{SiO}}_{4}$, respectively. The $^{3}$${\mathit{A}}_{2}$${\ensuremath{\rightarrow}}^{1}$${\mathit{A}}_{1}$ transition appears as a Fano antiresonance in the spectrum of ${\mathrm{Cr}}^{4+}$-doped ${\mathrm{Mg}}_{2}$${\mathrm{SiO}}_{4}$. The luminescence spectra are assigned to a transition from an excited triplet state, which is definitely not mixed with $^{1}$E contributions in ${\mathrm{Ca}}_{2}$${\mathrm{GeO}}_{4}$. The luminescence spectra are surprisingly sharp. Possible explanations are discussed. The luminescence of ${\mathrm{Cr}}^{4+}$-doped ${\mathrm{Ca}}_{2}$${\mathrm{GeO}}_{4}$ is much less quenched at room temperature than in the ${\mathrm{Mg}}_{2}$${\mathrm{SiO}}_{4}$ host. Finally, the spectroscopic properties of ${\mathrm{Cr}}^{4+}$-doped materials are compared with those of other 3${\mathit{d}}^{2}$ ions in tetroxo coordination. \textcopyright{} 1996 The American Physical Society.

Journal ArticleDOI
TL;DR: Data showed that posture control during balancing on unstable support surface consists mainly in adapting the motor program according to the postural requirements rather than in changes of thePostural strategy.

Journal ArticleDOI
TL;DR: In this paper, an improved drying procedure was proposed for anhydrous CeCl3, which was demonstrated to activate rapidly (in catalytic and stoichiometric amounts) ketones at room temperature, providing excellent addition of organometallic reagents.

Journal ArticleDOI
TL;DR: It seems very likely that the reduced ATP level under glucose-free conditions leads to an inhibition of the activity of Na+/K(+)-ATPase that results in reversal of the uptake processes and in [Ca2+]o-independent [3H]DA release from the axon terminals.

Journal ArticleDOI
TL;DR: In this paper, a class of standard finitely presented quadratic algebras over a fixed field, called binomial skew polynomial rings, are studied, and a condition called (∗) is imposed on the set of defining relations, which is necessary and sufficient for the existence of a finite Groebner basis of every one-sided ideal in the set.

Journal ArticleDOI
TL;DR: In this article, the authors studied resonances associated to the elasticity operator in the exterior of an arbitrary obstacle in R3 with Neumann boundary conditions and proved that there exists a sequence of resonances tending rapidly to the real axis.
Abstract: We study resonances (scattering poles) associated to the elasticity operator in the exterior of an arbitrary obstacle inR3 with Neumann boundary conditions. We prove that there exists a sequence of resonances tending rapidly to the real axis.