Showing papers by "Wrocław University of Technology published in 1981"

Density-free Bayes risk consistency of nonparametric pattern recognition procedures

Abstract: Pattern recognition procedures based on the Cesaro mean of orthogonal series are presented and their Bayes risk consistency is established. No restrictions are put on the class conditional densities.

Photoconductivity of Crystalline Iodoform I.

Abstract: Steady state photoconduction in iodoform has been studied between 210–400 nm. The photoconduction threshold is at 345 nm whereas the crystal absorption extends up to 480 nm. The photoconductivity action spectrum shows a steep rise of the photo carrier generation efficiency in the range 345–290 nm and a plateau at shorter wavelengths. Current-voltage characteristics measured under steady illumination show a square dependence of the photocurrent on applied voltage showing the influence of space charge effects. Electron photocurrents are three orders of magnitude lower than hole photocurrents. The lower limit of the photogeneration quantum yield is estimated as 6 × 10−3 charge carriers/photon with an applied field of 1 × 104 V/cm.

Inhibition of rat liver glutamine synthetase by phosphonic analogues of glutamic acid.

Abstract: Analogues of glutamic acid, α-methylglutamic acid and glutamine in which the α-or γ-COOH groups are replaced by PO3H2 or P(O)(OH3)OH functions competitively inhibit rat liver glutamine synthetase. The K1 values are comparable to or lower than KM for L-glutamate.

A novel method for determining the parameters of microbial kinetics

Abstract: It is conventional to describe the relationship between the specific rate of microbial growth and the concentration of the inhibitory substrate in terms of the Andrews–Edwards equation. A novel method for establishing the constants of this equation is presented. The equation is transformed to a polynomial and the empirical data are approximated by a quadratic polynomial. The results obtained for the biodegradation of phenol in a mixed culture (activated sludge) are discussed.

Rare earth oxide films: their preparation and optical properties

Abstract: The results of investigations into the production methods of Gd2O3, Eu2O3, Er2O3, Yb2O3 films are presented. A description of the optical properties contains the optical constants n and k of the films evaporated by an electron-beam gun in the 0.2–9-μm wavelength range. Interpretations of the IR absorption bands is given

Outline of a fuzzy logic approach to information retrieval

Abstract: An information retrieval method based on fuzzy logic is presented. The method described takes into account in a straightforward way the varying importance of descriptors which reflect the content of the information system documents as well as the varying formal relevance grades of documents in relation to a given query. The use of the simple operations of fuzzy logic allows retrieval of documents with the highest grades of formal relevance (in a given information system).

Porosity variation and swelling of cation exchangers

Abstract: Polystyrenesulfonic cation exchangers have been obtained from styrene-divinylbenzene copolymers modified with organic solvents The cation exchangers were characterized by varying porosity analogous to that of the parent copolymers The porosity varied from zero to 045 and the specific surface area from zero to 350 m2/g; these changes were induced by drying the cation exchangers from poorly solvating solvents The sorption degrees towards a model dye (methylene blue) from an aqueous solution reached a value up to unity and the pseudoequilibration time decreased with an increase in the sorption temperature The sorption degrees of the dye from an acetone solution were lower and proportional to swelling of the gel in acetone The presented results indicate that, similarly as in copolymers from which the cation exchangers were obtained, the structural changes occur on drying and they result from the surface tension of solvents, but the swollen cation exchangers have the gel structure Polystyrolsulfonsaure-Kationenaustauscher wurden aus mit organischen Losungsmitteln modifizierten Styrol-Divinylbenzol-Copolymeren synthetisiert Die Kationenaustauscher wurden wie die Ausgangspolymeren durch ihre Porositat charakterisiert Diese variierte von 0 bis 0,45, die spezifische Oberflache von 0 bis 350 m2/g Diese Unterschiede wurden erhalten, indem die Kationenaustauscher aus schlecht losenden Losungsmitteln durch Trocknen gewonnen wurden Die Sorptionsgrade, gegenuber dem Modellfarbstoff Methylenblau in wasriger Losung gemessen, erreichten den Wert eins, und die Pseudoequilibrierungszeit sank mit steigender Sorptionstemperatur Die Sorptionsgrade des Farbstoffs aus einer Acetonlosung waren geringer und dem Quellungsgrad des Gels in Aceton proportional Die Ergebnisse zeigen, das, ahnlich wie bei den Ausgangspolymeren, auch bei den Kationenaustauschern die strukturellen anderungen beim Trocknen eintreten, und das dies ein Ergebnis der Oberflachenspannung der Losungsmittel ist Die gequollenen Austauscher haben nach wie vor Gelstruktur

Selection of scientific journals based on the data obtained from an information service system

Abstract: A great and constantly growing number of scientific journals editions demands strict selection of journals during the planning of their purchase. The method of journal selection on the basis of the information service system data is described in this article. The primary value of a journal has been defined as an amount of the retrieved for the readers information concerning the articles published in a given journal. This parameter and the costs of subscription are the basis for journal ranking and determination of the number of copies (to be bought). This method has been verified by the use of data from the SDI system exploited at Wroclaw Technical University. Having compared the achieved results with the results of the simultaneously conducted questionnaire investigation, it has been found that there is a considerable degree of accordance between the results of journal acquisition planning based on the described method, and the demands of journal users.

Topography of ion-etched Corning 7059 glass

Abstract: Topographs of Corning 7059 glass, developed by 7Kv, 70μA Ar+ irradiation from a hollow anode ion gun were investigated. Two forms of surface topography were observed: lens-shaped cavities and waves. These are discussed in terms of measured sputtering yield against incidence angle relation or beam divergence. Practical applications in specimen preparation for transmission electron microscopy and glass homogeneity testing are suggested.

Structure variation in styrene-divinylbenzene copolymers and its influence on sorption properties

Abstract: The effect of a series of solvents on the structure of solvent-modified styrene-divinylbenzene copolymers has been investigated. It has been found that by a consecutive treatment of these copolymers with toluene, acetone, methanol, and water marked changes can be brought about in the structure of these copolymers which lead to the formation of, or increase in, their specific surface area. This phenomenon was explained by the disintegration of large aggregates into smaller ones and the parallel formation of a larger number of small pores. Such a treatment enhances the sorption properties of the copolymers. Der Einflus einer Reihe von Losungsmitteln auf die Struktur losungsmittelmodifizierter Styrol-Divinylbenzol-Copolymerer wurde untersucht. Es ergab sich, das sich durch nachfolgendes Behandeln dieser Copolymeren mit Toluol, Aceton, Methanol und Wasser die Struktur dieser Copolymeren merklich andert. Es wurde eine Vergroserung der spezifischen Oberflache der Polymeren beobachtet. Dieses Ergebnis wurde durch die Bildung kleinerer Aggregate aus groseren sowie durch die parallel erfolgte Bildung einer groseren Anzahl kleiner Poren erklart. Eine solche Behandlung erhoht die Sorptionseigenschaften der Copolymeren.

Synthesis and polymerization of p-bromomethylstyrene and p-lodomethylstyrene

Abstract: Synthesis of p-bromomethylstyrene (3) and p-iodome-thylstyrene (4) is reported. 3 was obtained by the bromomethylation of 2-phenylethyl bromide followed by dehydrobromination of the resultant p-(2-bromoethyl) benzyl bromide (2) with t-BuOK, as well as by cleaving p-vinyl-benzyl methanosulfonate with LiBr in the presence of 18--crown-6. 4 was obtained from p-chloromethylstyrene (1) via the Finkelstein reaction. 3 was polymerized successfully in the presence of free-radical initiators, but 4 was found to be too unstable to give a well-defined polymer.