Showing papers by "Jožef Stefan Institute published in 1994"
TL;DR: In this paper, Sb doped and undoped SnO2 thin solid coatings were prepared by the dip-coating technique via the sol-gel route, which was achieved through the addition of SbCl3 in the concentration range 1-10 mol%.
Abstract: Sb doped and undoped SnO2 thin solid coatings were prepared by the dip-coating technique via the sol-gel route. Aqueous gels of undoped compound were made by using a SnCl4 precursor and doping was achieved through the addition of SbCl3 in the concentration range 1–10 mol%. Fourier transform infrared (FTIR), ATR and near normal reflectance spectroscopic techniques were utilized to determine the vibrational spectra of aqueous gels, xerogels and oxides of Sb doped and undoped compounds. Analysis of the corresponding FTIR spectra revealed the existence of Sb-O modes at 770 cm−1. The drying of both types of gel was accompanied by the formation of hydrogen bonds of medium strength wit the OH-O length about 2.7–2.8 A. Some properties of pure and Sb doped oxide powders formed in the temperature range ≤1000°C were measured by the thermogravimetry, X-ray diffraction and FTIR spectroscopic techniques. The doping brought about a broadening of the X-ray diffraction peaks. The reflectivity of the samples increased in the spectral range 4000-600 cm−1 up to 60%, due to the formation of plasma modes. Thin solids films were made by the dip-coating method. The efficiency of the dip-coating process was 0.02–0.1 μm per dipping, depending on the viscosity of the gel. The electrical resistivity of the doped SnO2 coatings was about 1.2 × 10−2 ω cm and thus comparable to the electrical resistivity of the alkoxide derived Sb doped SnO2. Doping decreased visible transmittance ∼5% but infrared reflectance increased up to 40%, depending on the film thickness.
116 citations
TL;DR: A simplified mathematical model is introduced which is used to determine the workspace related to the reachability of the wrist and represents the spatial motion of two characteristic points, epicondylus lateralis and proc.
Abstract: The paper introduces a simplified mathematical model of the human arm kinematics which is used to determine the workspace related to the reachability of the wrist. The model contains six revolute degrees of freedom, five in the shoulder complex and one in the elbow joint. It is not directly associated to the anatomical structure of the arm, but represents the spatial motion of two characteristic points, epicondylus lateralis and proc. styloideus. Use of this simplified model for the determination of reachable workspace offers several advantages versus direct measurement: (i) the workspace can be obtained in few minutes on a micro VAX II computer, (ii) patients with various injuries in various stages of recovery can be treated since only a few brief and simple measurements of the model's parameters are needed, and (iii) the calculated workspace includes complete information of the envelope, as well as inside characteristics. >
105 citations
TL;DR: The effect of neutral or alkaline pH on cathepsin B activity and structure was investigated and the good agreement of the rate constants of inactivation and unfolding of the enzyme indicates an important structure-function relationship.
Abstract: The effect of neutral or alkaline pH on cathepsin B activity and structure was investigated. An irreversible loss of activity, accompanied by large structural changes, was observed at pH > or = 7.0. The high activation energy of 183.5 kJ mol-1, calculated for the inactivation process, is in good agreement with structural changes observed by circular dichroism. Both the pH-induced inactivation and the pH-induced unfolding of cathepsin B were found to be first-order processes, exponentially increasing with increasing pH of the solution. The good agreement of the rate constants of inactivation and unfolding of the enzyme indicates an important structure-function relationship. Cathepsin B was also found to be destabilized both by increasing ionic strength and organic solvent content.
84 citations
25 Aug 1994
TL;DR: In this article, a technique for learning qualitative models of dynamic systems is described, and the problem of learning QSIM-type models is formulated in logic and the GOLEM learning program is used for induction.
Abstract: A technique is described for learning qualitative models of dynamic systems. The QSIM formalism is used as a representation for learned qualitative models. The problem of learning QSIM-type models is formulated in logic, and the GOLEM learning program is used for induction. An experiment in learning a qualitative model of the connected containers system, also called U-tube, is described in detail.
83 citations
TL;DR: In this paper, the coherent twin boundary in BaTiO3 was investigated using high-resolution transmission electron microscopy and spatially resolved electron-energy-loss spectroscopy (EELS).
Abstract: The coherent (111) twin boundary in BaTiO3 has been investigated using quantitative high-resolution transmission electron microscopy and spatially resolved electron-energy-loss spectroscopy (EELS). Lattice images under different defocusing conditions were obtained and compared with simulated images for different structural models. An excellent match between calculated and observed images was obtained only for the model where the Ba-O3 plane constitutes the twin boundary. The oxidation state of Ti at twin boundaries was interrogated by studying the near-edge structure of the L23 ionization edge of Ti using spatially resolved EELS. The difference between spectra taken from the bulk and those including the boundary indicates the presence of Ti in a reduced oxidation state at the boundary. The charge is compensated by oxygen vacancies Vo in the twin plane, which is therefore composed of Ba-O3-x[Vo]x instead of Ba-O3.
79 citations
TL;DR: The exposure of fish to various concentration levels (sub‐lethal) of chromium under laboratory and field conditions caused an increase in the frequency of micronuclei compared with the control groups.
Abstract: An investigation of the cytogenetic effects of chromium (Cr(VI) and Cr(III)) in Prussian carp (Carassius auratus gibelio) was made. For detecting cytogenetic damage, micronuclei induction in fish erythrocyte cells was employed. Fish were investigated 100 m above and 400 m below the discharge of leather waste products into the river Ljubljanica, and by exposing fish to three doses of chromium (Cr(VI) and Cr(III)) in the laboratory. The exposure of fish to various concentration levels (sub-lethal) of chromium under laboratory and field conditions caused an increase in the frequency of micronuclei compared with the control groups.
78 citations
TL;DR: This novel approach to genotoxicity testing using binucleated cytokinesis-blocked erythrocytes in fish appears to be worth further study as a method for monitoring the genotoxic effects of waterborne pollutants.
Abstract: The genotoxic effects of low concentrations of Se(IV), Hg2+, and CH3HgCl added separately or together (Se(IV)/CH3HgCI) were studied by determining the induction of micronuclei in the binucleated erythrocytes of Prussian carp. The frequencies of micronuclei were elevated in a dose-dependent manner in all treatments when compared to the relevant controls. Addition of Se(IV) reduced the frequencies of micronuclei in treatments with both forms of mercury. This novel approach to genotoxicity testing using binucleated cytokinesis-blocked erythrocytes in fish appears to be worth further study as a method for monitoring the genotoxicity of waterborne pollutants.
67 citations
TL;DR: In this article, the First and Second Order Reliability Methods (FORM and SORM) have been applied in the safety assessment of steam generator tubes with through-wall axial stress corrosion cracks.
56 citations
01 Jan 1994
56 citations
TL;DR: A specific, high-affinity binding site for ammodytoxin C in synaptic membranes from bovine cerebral cortex was detected and partially characterized and overlaps, at least partially, with the neuronal acceptors for some of the related presynaptically neurotoxic phospholipases A2 (beta-neurotoxins).
Abstract: A specific, high-affinity binding site for ammodytoxin C in synaptic membranes from bovine cerebral cortex was detected and partially characterized. Equilibrium binding analysis revealed a single population of [125I]ammodytoxin C acceptors with the following binding parameters: Kd = 6.0 nM and Bmax = 5.7 pmol/mg membrane protein. Such binding was strongly inhibited by three ammodytoxins (A, B, and C) and by crotoxin B. Vipera berus berus phospholipase A2 was a weaker inhibitor; nontoxic phospholipase A2, ammodytin I2, and the myotoxic phospholipase A2 homologue, ammodytin L, both from Vipera ammodytes ammodytes venom, inhibited binding only at very high concentrations, whereas alpha-dendrotoxin, beta-bungarotoxin, and crotoxin A had no influence on the [125I]ammodytoxin C-specific binding. The ammodytoxin C neuronal binding site therefore overlaps, at least partially, with the neuronal acceptors for some of the related presynaptically neurotoxic phospholipases A2 (beta-neurotoxins). [125I]-Ammodytoxin C was covalently attached to its acceptor by chemical cross-linking. Subsequent SDS-PAGE analysis followed by autoradiography revealed saturably labeled membrane components with apparent M(r) values of 51,000 (weaker band) and 53,000-56,000 (stronger band). Pretreatment of synaptic membranes with Staphylococcus aureus V-8 proteinase and proteinase K, heat, or low pH decreased the [125I]ammodytoxin C-specific binding to various extents, but never abolished it completely. Membrane protein and certain phospholipids residing in its vicinity are therefore most likely involved in the binding of ammodytoxin C to bovine synaptic membranes.
38 citations
TL;DR: In this paper, electric currents through small conductive samples were measured and a series of 2D electric-current distributions through the selected slice with a plane resolution of 60 × 60 μm was presented.
TL;DR: Grain growth in donor doped BaTiO3 was studied below the temperature of liquid phase formation and it was found that a high donor concentration and high oxygen partial pressure effectively inhibit grain growth rate during sintering.
Abstract: Grain growth in donor doped BaTiO3 was studied below the temperature of liquid phase formation. It was found that a high donor concentration and high oxygen partial pressure effectively inhibit grain growth rate during sintering. Defect chemistry, derived from a model consistent with electrical measurements, well describes the grain growth properties of donor doped BaTiO3 in the subsolidus grain growth region.
TL;DR: The kinetics of the complex formation between bovine cathepsin S and bovines stefin B was studied by conventional and stopped‐flow techniques and the competitive nature of inhibition was confirmed.
15 Jan 1994-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The Forward Ring Imaging Cherenkov detector of the DELPHI experiment at LEP provides hadron identification at polar angles 15° < θ < 35° and 145° < ǫ < 165°.
Abstract: The Forward Ring Imaging Cherenkov detector of the DELPHI experiment at LEP provides hadron identification at polar angles15° < θ < 35° and 145° < θ < 165°. Two radiator media, a layer of liquid C6F14 and a volume of gaseous C4F10, in combination provide coverage of momenta up to 40 GeV/c. A single array of photosensitive Time Projection Chambers registers the impact points of ultraviolet photons from both radiators. The design of the detector and of its readout system is described. First results obtained with a partly installed detector are reported.
TL;DR: A variety of task scheduling policies for use with real-time embedded systems are described, including commonly used practical strategies as well as new ideas from the research community.
CERN1, National and Kapodistrian University of Athens2, DSM3, Collège de France4, University of Grenoble5, University of Paris6, University of Mons7, Uppsala University8, University of Genoa9, Niels Bohr Institute10, Federal University of Rio de Janeiro11, National Technical University12, University of Wuppertal13, Jožef Stefan Institute14
01 Apr 1994-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the DELPHI ring imaging Cherenkov detector system was designed to do particle identification over most of the solid angle in the momentum range from ∼2 GeV c to ∼40 sol GeVc.
Abstract: The ring imaging Cherenkov detector system in the DELPHI experiment at the Large Electron-Positron storage ring at CERN, is designed to do particle identification over most of the solid angle in the momentum range from ∼2 GeV c to ∼40 sol GeV c . Two radiator media are used to cover the momentum range; (i) a 1 cm layer of liquid C6F14, and (ii) a volume filled with gaseous C5F12 or C4F10. Photosensitive time projection chambers record the conversion points of the ultraviolet photons produced in both radiator systems. The total active area is ∼30 m2 in the barrel region and ∼8 m2 in the two endcaps. The design of the detector systems is described in this paper. We will also report performance figures and compare them to simulation studies.
TL;DR: In this article, an expression for the self-diffusion attenuation of the spin echo is derived that is valid for a strong non-uniform magnetic field, and it is shown that the nonuniform field must have the appropriate spatial symmetry and that only isotropic selfdiffusion can be measured with the new method.
TL;DR: The goal of the research is to show that using advanced artificial intelligence techniques, measurements, and some general basic knowledge about the ecosystem suffice to automatically generate better models and in less time than is the case by traditional construction of models.
TL;DR: Synthetic gene coding for human cysteine proteinase inhibitor stefin B was expressed in Escherichia coli by the use of pKP1500 plasmid-containing tac promotor and temperature-sensitive origin of replication, ensuring high Plasmid copy number.
TL;DR: It is suggested that the basic difference between the stefins is the domination of hydrophobic interaction in the stabilization of stefin B, which is due to its non-specific nature leading to the formation of a molten globule intermediate.
Abstract: Homology modelling has been used to model stefin A based on the X-ray structure of stefin B. Several models have been produced by interactive modelling or positioning of the side chains by Monte Carlo procedure with simulated annealing. The quality of models was evaluated by calculation of the free energy of hydration, 3D-1D potential or buried area of surface accessibility. Stefin A is a thermostable protein, exhibiting a two-state denaturation, while stefin B denatures at a 40 degrees C lower temperature and forms a stable molten globule intermediate under mild denaturing conditions. From the tertiary structures, thermodynamic functions were predicted, conforming closely to the experimental calorimetric results. Polar and apolar buried areas of surface accessibility were obtained by structural deconvolution of the thermograms. It is suggested that the basic difference between the stefins is the domination of hydrophobic interaction in the stabilization of stefin B, which is due to its non-specific nature leading to the formation of a molten globule intermediate. Modelling of stefin A predicts increased numbers of hydrogen bonds which stabilize it and increase the cooperativity of its denaturation.
05 Sep 1994
TL;DR: The presented distributed algorithm is based on the sequential Takahashi-Matsuyama algorithm and has been implemented as a set of node algorithms, which interact mutually and make collective decisions concerning multipoint liaison setup.
Abstract: Conventional Steiner tree algorithms have provided good solutions to the problem of multipoint virtual liaison construction in the networks where the complete knowledge of their topology was available in particular network nodes. As integrated service communication networks are growing towards a worldwide global network, the need for a distributed approach emerges where each network node is supposed to know only the topology of its vicinity. The presented distributed algorithm is based on the sequential Takahashi-Matsuyama algorithm (H. Takahashi and A. Matsuyama, 1980) and has been implemented as a set of node algorithms, which interact mutually and make collective decisions concerning multipoint liaison setup. Simulation results have shown that the efficiency of the proposed algorithm is practically identical to that of the distributed Kou-Markovsky-Berman algorithm (L. Kou, G. Markovsky, L. Berman, 1981), whereas it substantially surpasses DKMB as regards time complexity. >
TL;DR: In this article, three sandwich layers of an Si/Me/Si structure, where Me ≡ Al, Ni or Cr, with a total thickness between 116 and 170 nm were sputter deposited onto smooth silicon (111) substrates.
TL;DR: A spectrophotometric method for measuring the chemical yield in radiochemical neutron activation analysis of selenium in feedstuffs and biological materials is described in this paper, which is based on measuring the absorbance at 350nm, which is due to the 5-nitro-2, 1, 3, 3-benzoselenadiazole complex formed between the two elements.
Abstract: A spectrophotometric method for measuring the chemical yield in radiochemical neutron activation analysis of selenium in feedstuffs and biological materials is described. The method is based on measuring the absorbance at 350nm, which is due to the 5-nitro-2, 1, 3-benzoselenadiazole complex formed between selenium and 4-nitro-1, 2-diaminobenzene. The technique was checked against radiotracer techniques using 75Se or 81mSe, and was illustrated by results for different botanical samples and certified reference materials.
TL;DR: It is suggested that reduced binding of stefins with elongated amino termini is caused by the mini chain of cathepsin H which is probably in close proximity to the aminotermini in the complexes.
Abstract: Two mutants of the cysteine proteinase inhibitor, stefin B, were prepared by ligating the amino-terminal region from cystatin C and kininogen, members of two other families of cystatin superfamily. The mutant proteins were expressed in Escherichia coli and purified to homogeneity. Inhibition and kinetic constants were determined for authentic and mutated stefins against the four different cysteine proteinases, papain and human cathepsins B, L and H. Inhibition of both amino-terminal elongated stefin B mutants was decreased particularly for cathepsin H. A model of the tertiary structure of cathepsin H and its complex with stefin B was constructed. The framework for the model of cathepsin H consisted of structurally conserved regions from tertiary structures of three cysteine proteinases. Variable regions were selected from fragments of other proteins from the protein data base. We suggest that reduced binding of stefins with elongated amino termini is caused by the mini chain of cathepsin H which is probably in close proximity to the amino termini in the complexes. This mini chain is bridged to Cys214 and has already been proposed to be responsible for the aminopeptidase activity of cathepsin H. We conclude that the amino-terminal region of stefin B plays an important role in determining the strength of inhibition of cathepsin H.
01 May 1994
TL;DR: This paper describes an approach to the interpretation of discrete event simulation results using machine learning techniques and discovered some interesting regularities that were thereby automatically discovered.
Abstract: This paper describes an approach to the interpretation of discrete event simulation results using machine learning techniques. The results of two simulators were processed as machine learning problems. Interpretation obtained by the regression tree learning system Retis was intuitive but obviously expressed in a complicated way. To enable a more powerful knowledge representation, Inductive Logic Programming (ILP) system Markus was used, that also highlighted some attribute combinations. These attribute combinations were used as new attributes in further experiments with Retis and Assistant. Some interesting regularities were thereby automatically discovered.
TL;DR: Remedial actions were carried out in two kindergartens with average heating season radon concentrations of about 2,000 Bq m-3, thus reducing radon levels to an acceptable value.
Abstract: Remedial actions were carried out in two kindergartens with average heating season radon concentrations of about 2,000 Bq m{sup -3}. The first kindergarten is built on sedimentary gravel and the second one on fly ash and cinder fill. In both cases, radon accumulated in a sub-floor channel (service tunnel). The channels were opened at both ends. Natural ventilation of the tunnels did not produce a sufficient reduction in radon concentration. A fan was mounted in one kindergarten to ventilate the channel for 20 min three times each day, thus reducing radon levels to an acceptable value. 5 refs., 5 figs., 1 tab.
TL;DR: In this paper, the extraction efficiency of total water-soluble chromium and chromium(VI) in clay, peat and sandy soils was investigated, where water and a KH2 PO4 solution (0.015 mol dm−3) were used as extradants.
Abstract: The parameters influencing the extraction efficiency of total water-soluble chromium and chromium(VI) in clay, peat and sandy soils were investigated. Water and a KH2 PO4 solution (0.015 mol dm−3) were used as extradants. Samples were ultrasonicated or shaken in classical shakers. Variations of solution volume-to-soil weight ratio, and of shaking time were studied in order to develop the optimal extraction procedure for the determination of total water-soluble chromium and chromium(VI). Soil samples treated with tannery waste continuously for 17 years and soils freshly contaminated with the same waste were studied.
TL;DR: In this article, the levels and residue profiles of polychlorobiphenyls (PCB), polychloronaphthalenes (PCN), and chlorobenzenes (CBz) in plants (grass, pine needles) from a region contaminated with the corresponding technical compounds from an electroindustrial plant are presented.
TL;DR: In this article, the density of atomic hydrogen in the vicinity of the probe is calculated from the measured data on the energy dissipated on the probe surface in a unit time, and the density was measured at different total pressures in a vacuum system between 6 × 10−2 mbar and 2 × 101 mbar.
01 Oct 1994
TL;DR: The passive state of Ni-Cr (80/20) coatings prepared by a plasma beam sputter deposition process was studied using cyclic voltammetry and impedance spectroscopy techniques.
Abstract: The passive state of Ni–Cr (80/20) coatings prepared by a plasma beam sputter deposition process was studied using cyclic voltammetry and impedance spectroscopy techniques. The highly protective quality of the film formed in acetate buffer, pH = 5.7, is probably based on chromic species. The nickel content in the film was very low and influenced only the electronic properties of the film.
The appearance of a distinct transition in the capacitance potential characteristic may be correlated with the presence of higher valent chromium species. Cyclic voltammetry demonstrated that Cr(VI) was incorporated into the outer part of the oxide film, or was tenaciously adsorbed on the electrode surface. Its formation and reduction were reversible.