Showing papers by "Wrocław University of Technology published in 1991"
TL;DR: Aminophosphonates are analogues of amino acids in which a carboxylic moiety is replaced by phosphonic acid or related groups that inhibit enzymes involved in amino acid metabolism and thus affect the physiological activity of the cell.
Abstract: Aminophosphonates are analogues of amino acids in which a carboxylic moiety is replaced by phosphonic acid or related groups. Acting as antagonists of amino acids, they inhibit enzymes involved in amino acid metabolism and thus affect the physiological activity of the cell. These effects may be exerted as antibacterial, plant growth regulatory or neuromodulatory. Chosen representative examples of biologically active aminophosphonates are presented in some detail.
899 citations
TL;DR: A review of recent developments in the spectroscopy of the chromium ion covering the literature published mostly in the last decade can be found in this paper, where the authors focus on the high-oxidation state of chromium(VI) ion.
73 citations
TL;DR: It is shown that the decision form of the problem dealt with is NP-complete in the strong sense for the case of identical release date reduction rates and some efficiently solvable cases and an approximate algorithm are shown.
66 citations
TL;DR: Both Pb(II) and UO2�2+ were abstracted from aqueous solution by both living and dead biomasses of Streptomyces sp. as discussed by the authors.
Abstract: Both Pb(II) and UO2
2+ were abstracted from aqueous solution by both living and dead biomasses of Streptomyces sp. The organisms were particularly effective in taking up UO2
2+ ions. Optimum pH for both metals was pH 5 to 6. For a UO2
2+ concentrations of 1 mmol L−1 and a dead biomass concentration of 1 g L−1, 60% of the UO2
2+ was removed from solution. If cell wall material of the organism was prepared from a killed biomass an equal weight of the material removed 90% of the UO2
2+ from solution. in this case accumulated U in the biomass was 0.9 mmol g−1 of dry biomass. Electron micrographs showed clearly that the Pb abstracted was only in the microorganisms cell surface, but UO2
2+ uptake was also intracellular.
57 citations
TL;DR: A program of singularity theory is claimed to be of systematic use in robotics and complete lists of normal forms are proposed and are regarded as candi date models of kinematics of robot manipulators.
Abstract: In this paper a program of singularity theory is pro claimed to be of systematic use in robotics. Complete lists of normal forms are proposed and are regarded as candi date models of kinematics of robot manipulators. Argu ments for the applicability of candidate normal forms to manipulator kinematics are provided. Singularities and bifurcation diagrams of the normal forms are examined and consequences derived for the inverse kinematic prob lem in redundant kinematics with singularities.
41 citations
TL;DR: To recover the system nonlinearity the Legendre orthogonal polynomials based procedure is proposed and the procedure consistency and the rate of convergence are established.
41 citations
TL;DR: In this paper, the synthesis of a series of phosphonic acid analogues of this diamino-dicarboxylic acid is described: mono- and diphosphonic acid derivatives as well as their homologues, N -alkyl analogues and some peptidyl derivatives.
39 citations
TL;DR: The presence of Pb(II) on the bacterium's cell walls significantly increased flotation even in the absence of the collector, and addition of SDS further increased both flotation rate and recovery.
Abstract: The flotation of Streptomyces pilosus was studied in the absence and presence of adsorbed Pb(II) ions on the cell walls and with and without using sodium dodecylsulfate (SDS) as collector. Adsorption of SDS onto the organism in the absence and presence of Pb(II) ions was also investigated. It was found that in the absence of adsorbed Pb(II), very little flotation took place with or without the presence of SDS although SDS adsorbed to some extent on the organism. The presence of Pb(II) on the bacterium's cell walls significantly increased flotation even in the absence of the collector. Addition of SDS, however, further increased both flotation rate and recovery.
37 citations
01 Nov 1991
TL;DR: Methods based on the Fourier technique for real-time determination of the basic waveforms of signals and their recursive implementation can be applied to the control and protection of electrical power systems.
Abstract: Methods based on the Fourier technique are widely used for real-time determination of the basic waveforms of signals. The paper presents possibilities for the recursive implementation of these methods. Recursive algorithms have the same properties (frequency characteristics, response time) as nonrecursive ones, but they reduce the time of calculation very efficiently. The methods presented can be applied to the control and protection of electrical power systems.
35 citations
01 Nov 1991
TL;DR: In this article, an analysis of the electronegativity and hardness of a bonded atom (A) is given on the ground of the Hartree-Fock Hamiltonian and based on Mulliken population analysis.
Abstract: An analysis of the electronegativity (χ A ) and hardness (η A ) of a bonded atom (A) is given on the ground of the Hartree-Fock Hamiltonian and based on Mulliken population analysis. Practical expressions for χ A and η A are developed within the Koopmans approximation. Electronegativity equalization (EE) has not been pursued, partial EE has been obtained, though. The resulting indices χ A and η A describe correctly atoms in simple molecules. The directional effect of the substituent in the benzene ring is properly rationalized and enhanced by means of the electronegativity and hardness of the ring carbons.
34 citations
TL;DR: In this paper, the authors studied the transport of Amino acid hydrochlorides through 1-decanol membranes supported by a porous polyacrylonitrile hollow fiber matrix and found that the choice of the membrane phase, the kind of polymeric support and the mode of membrane preparation are of great importance for the efficiency of the process.
TL;DR: In this article, the results of pollution tests with AC voltages were carried out with a multiunit zinc oxide arrester and the interaction between the polluted porcelain housing and the inner varistor column due to capacitive coupling has been found to be responsible for the temperature rise of varistor elements.
Abstract: Results of pollution tests with AC voltages which were carried out with a multiunit zinc oxide arrester are presented. The interaction between the polluted porcelain housing and the inner varistor column due to capacitive coupling has been found to be responsible for the temperature rise of varistor elements. Different voltage distributions inside and outside the arrester cause a high radial electric field which can lead to internal discharges if the radial insulation system is not properly designed. These internal discharges may damage varistor elements which are not adequately coated and may cause the total destruction of the arrester. The shape of the internal and external currents due to discharges is analyzed. A test method for comparing different arrester constructions under severe pollution is proposed. The method can also be used to demonstrate the absence of discharges for a certain arrester design under extreme conditions of pollution during type tests. >
TL;DR: It is concluded that juvenile-hormone binding induces a conformational transition of its carrier protein, which might have a physiological significance for signal transmission.
Abstract: A juvenile-hormone-binding protein (juvenile-hormone carrier), isolated fromGalleria mellonella haemolymph, was treated with trypsin, chymotrypsin, carboxypeptidase A and subtilisin. Among these enzymes, only subtilisin was able to affect juvenile-hormone-binding activity of this protein. With SDS/PAGE it was shown that juvenile-hormone-binding protein, a 32-kDa peptide, is first slowly converted into a 30-kDa molecule, then into two or three smaller-molecular-mass species (20–25 kDa), which in turn were further digested to small peptides undetectable in PAGE. The 30-kDa peptide has a 2.4-times-higher dissociation constant for juvenile hormone than the native protein. No binding activity was detected for 20–25-kDa peptides. The rate of proteolysis of juvenile-hormone-binding protein was decreased by more than twofold in the presence of hormone, however, the overall cleavage pattern was unchanged. Under non-denaturing conditions, free binding-protein molecules could be separated from juvenile-hormone–binding-protein complex due to a slower electrophoretic mobility of the complex. As judged from ultracentrifugation and cross-linking experiments, binding of the hormone to its haemolymph carrier does not induce formation of oligomers, but shifts the sedimentation coefficient from 2.30S to 2.71S. It is conclude that juvenile-hormone binding induces a conformational transition of its carrier protein. This hormone-induced change might have a physiological significance for signal transmission.
TL;DR: In this article, two simple electron detectors (low and high take-off angles) for lowvoltage scanning electron microscopy were built and tested, which are able to detect backscattered electrons with high efficiency.
Abstract: Two simple electron detectors (low and high take-off angles) for low-voltage scanning electron microscopy were built and tested. They contain large area scintillators with an applied high voltage and are able to detect backscattered electrons with high efficiency. These detectors also can record the sum of backscattered and secondary electrons. The primary beam of the microscope is screened from the scintillator high voltage by grids, which also permit switching from the BSE to the (SE + BSE) mode. The circular symmetry of the grids minimizes the influence of applied potentials on the primary beam. The use of the low and high take-off detectors permits the detection of back-scattered electrons emitted from the specimen surface into different ranges of take-off angles.
TL;DR: In this paper, an experimental investigation of batch ion flotation of the transition metal cations Cr3-, Fe3+, Mn2+, Co2+, Zn2+, Ag+, Cd2+, and In3+ was presented.
Abstract: An experimental investigation is presented of the batch ion flotation of the transition metal cations Cr3-, Fe3+, Mn2+, Co2+, Zn2+, Ag+, Cd2+, and In3+ from acidic aqueous solutions with sodium dodecylsulfonate and sodium dodecylben-zenesulfonate as anionic surfactants. The selectivity sequences Mn2+ < Zn2+ < Co2+ < Fe3+ < Cr3+ and Ag+ < Cd2+ < In3+ are established, both from data for single and multi-ion metal cations solutions, where sublate was not formed in the bulk solution. Good agreement between the selectivity sequences and the values of ionic potential of metal cations was found. An experimental investigation was also performed on the solubility of sublates. The sublates solubility values are discussed in terms of ionic potentials of metal cations as well as of the surfactant size.
TL;DR: The redox properties of 1,1′-ferrocene-disulfonate-doped polypyrrole showed stabilization of iron(II) in the polymer as mentioned in this paper.
TL;DR: Three efficient approximation algorithms are described and analyzed that guarantee worst-case performance bounds of n −1, 2 and 5 3 .
TL;DR: In this article, a triacylglycerol lipase was purified from Pseudomonas fluorescens wild strain by chromatography on DEAE-cellulose and octyl-Sepharose CL-4B.
Abstract: Lipase (triacylglycerol lipase, EC 3113) has been purified from Pseudomonas fluorescens wild strain by chromatography on DEAE-cellulose and octyl-Sepharose CL-4B The yield was 21% and the specific activity of the purified enzyme 4780 U/mg protein It showed a Mr of about 45 times 10(4) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis The enzyme is active over a wide pH range and at 50–55 degrees C
TL;DR: A worst-case analysis of an algorithm proposed by Dannenbring for the m-machine permutation flow-shop problem is presented and the performance ratio of m / @/2 is found.
TL;DR: In this article, the possibility of a self-sustained magnetron sputtering process without the presence of an inert gas is demonstrated, which combines the advantages of both electron beam evaporation (purity, rate) and sputtering (good adhesion, repeatability, free choice of deposition geometry).
Abstract: The possibility of a self-sustained magnetron sputtering process, without the presence of an inert gas, is demonstrated. The advantages of this process are as follows: the possibility of thin metal film deposition at very low pressures p ⩽ 4 × 10−4 Torr; a very high sputtering rate; an absence of inert gas particles in the deposited films; a possibility of deposition on substrates placed at a distance from the target much smaller than the mean free path; a decrease in the plasma discharge influence on substrate, the substrate can be placed at a greater than usual distance from the target. Low pressure magnetron sputtering using target ions opens new possibilities for thin film deposition. The method combines the advantages of both electron beam evaporation (purity, rate) and sputtering (good adhesion, repeatability, free choice of deposition geometry).
TL;DR: In this paper, the authors considered the problem of spatial dynamic response of a suspension bridge to the passage of trains of concentrated forces with random values, and developed a computer-oriented algorithm aimed at the numerical solution of the problem.
Abstract: The problem of spatial dynamic response of a suspension bridge to the passage of trains of concentrated forces with random values is considered. The arrival of forces at the bridge is assumed to constitute a Poisson process of events. Such an excitation process is an appropriate model of vehicular traffic loads acting on the bridge. The bridge is idealized by a single-span thin-walled beam underslung to two cables. The response of the bridge in the space-time domain is described by a coupled system of non-linear, integro-differential equations. The dynamic influence functions of vertical and horizontal deflections at each cross-section point are obtained for the linear case. Cumulants and probability density functions of response are determined. Numerical methods have been used to develop a computer-oriented algorithm aimed at the numerical solution of the problem. As examples, numerical results for a particular bridge with some practical load cases are presented and illustrated by graphs.
TL;DR: In this article, the influence of petrographic constituent mineral substances on the reactivity and porosity development of coal char grains has been assessed from their behaviour in the reactions of model composite chars (obtained from brown coal humic acids (HA) doped with the macerals low temperature ash (LTA)).
TL;DR: In this paper, the pyroelectric properties of (CH3NH3)5Bi2Cl11 crystals were measured in the range 100-320 K and a ferropy-roelectric type phase transition at 170 K was confirmed.
Abstract: The pyroelectric properties of (CH3NH3)5Bi2Cl11 crystals were measured in the range 100–320 K. A ferropyroelectric type phase transition at 170 K was confirmed. Critical exponent β ≃ 0.5 was found in the region 0.5–12 K below Tc = 307 K.
TL;DR: Copper chromate and dichromate complexes with 2,2′-bipyridyl and 1,10-phenanthroline were synthesized and characterized (UV-vis, IR, FIR, ESR and thermal data) as discussed by the authors.
TL;DR: In this article, surface tension measurements were performed for individual monoethers of oligooxyethylene glycols and individual oligoxypropylene analogs in aqueous solution at 293.15 K.
TL;DR: In this article, an investigation was made into the kinetics and mechanism of pressure reduction with hydrogen of aqueous cobalt(II) from acetate solution containing powdered aluminium, and the effect of temperature, initial pH of the feed solution, partial pressure of hydrogen, stirring rate, and total surface area of the powdered aluminium on the course of reduction and on the quality of the resultant Co(Al) composite powder.
TL;DR: In this article, the properties of nine selected samples of Polish brown coals from both strip mines and perspective deposits varying in lithotype have been determined, which involved technical analysis of the elementary, group and petrographie compositions.
TL;DR: In this paper, general relations between viscometric and volumetric properties of polymers as functions of temperature and deformation conditions (shear rate or shear stress) have been derived.
Abstract: Using the free volume theory, general relations between viscometric and volumetric properties of polymers as functions of temperature and deformation conditions (shear rate or shear stress) have been derived. In particular, it has been shown that thermal expansion of polymers can be calculated from viscometric data. The obtained relations have been applied for description of the rheological behavior of polymer blends. Theoretical predictions have been compared with experimental data. Good agreement between theory and experiment has been stated if rheological properties of blends were compared at a constant shear rate.
TL;DR: A simple stochastic model assuming continuous traits, normally distributed modifications, selection for fertility and multiplicative fitness was used to simulate phenotypic evolution by “reproducing individuals” in a given fitness landscape, exhibiting a strong dualism.
Abstract: A simple stochastic model assuming continuous traits, normally distributed modifications, selection for fertility and multiplicative fitness was used to simulate phenotypic evolution by "reproducing individuals" in a given fitness landscape. Of particular interest was how small populations cross saddles separating distinct adaptive peaks. The simulated evolution exhibits a strong dualism: at the same level of reproductive errors, sexual reproduction provides significantly better local adaptation and asexual repreduction provides significantly better adaptive dynamics.