01 (1995) Scientific papers, Series A
Permanentní URI k tomuto záznamuhttps://hdl.handle.net/10195/38111
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Článek Otevřený přístup peer-reviewedpublished Use of plastic membrane ion-selective electrodes for the analysis of drug substances(Univerzita Pardubice, 1995) Shoukry, Adel F.An overview is given on plastic membrane ion-selective electrodes of the conventional and/or coated-wire type constructed for 23 drug compounds. These are based on incorporation of ion-pairs or ion-associates in poly(vinyl chloride) network in the presence of dioctyl phthalate as a plasticizer. The electrodes are very selective to their respective drugs; a comparative study proved that stereospecifity is a major factor affecting their selectivity. They have a relatively large working pH-ranges (more than 4 pH units for most cases). The isothermal temperature coefficients. (dE°/dT) of the electrodes range from 2.5×10-5 to 32.0×10-4 V/°C over a wide temperature limits. The electrodes can be employed successfully for assaying the investigated drugs in many of their pharmaceutical preparations.Článek Otevřený přístup peer-reviewedpublished Preparation and reactions of diazonium salts. II. Reactions of ArN2+(Univerzita Pardubice, 1995) Štěrba, VojeslavArenediazonium slats can react with nucleophiles in three ways: (1) The substitution of diazonium group by nucleophile, (2) the substitution of a substituent at ortho or para position by a nucleophile, (3) the addition of a nucleophile to the diazonium group producing the corresponding diazo compound Ar-N=N-Nu od a five- or six-membered ring if the nucleophile is presented by an ortho-standing substituent with regard to the diazonium group.Článek Otevřený přístup peer-reviewedpublished Preparation and reactions of azo compounds(Univerzita Pardubice, 1995) Vrba, ZdeněkThe term azo compounds involves the compounds of general formula R-N=N-R´ where the nitrogen atoms of the azo group N=N are bound with carbon atoms of the groups R and R´. From among the large variety of such combinations practically important are those in which both groups (R, R´) or at least one of them have aromatic character. Extraordinarily important are compounds having hydroxy and/or amino groups in positions conjugated with the azo group since they are intensively coloured, can be widely modified to obtain various physico-chemical properties, and are relatively easily available.Článek Otevřený přístup peer-reviewedpublished Catalysis for propene oxidation to acrylic acid(Univerzita Pardubice, 1995) Tichý, Josef; Machek, Jaroslav; Švachula, JiříCatalysts used in industry represent, in many cases, multicomponent compounds and/or their mixtures therefore. The catalytic properties depend not only on a suitable selection of elements but also on the way of preparation. To optimise this chemical process, a great many different parameters have to be taken into account. It is useful to utilize the methods of mathematical statistics for effective research. This paper shows the use of the Plackett-Burman statistical block in exploring the significant variable parameters of preparing multicomponent oxide catalysts for the oxidation of propene and acrolein.Článek Otevřený přístup peer-reviewedpublished Bestimmung der Temperaturabhängigkeit der Dichte von Rapsöl und Rapsöl-Methylester (Biodiesel) unter Anwendung der Methode der Volumen-ausdehnung(Univerzita Pardubice, 1995) Skopal, František; Komers, KarelSimple methods and apparatus for determination of the density of liquids at variable temperatures were developed. Their correct function was demonstrated by the comparison of the literature and experimental data for ethanol. The temperature dependences of the density of crude rape seed oil and of rape seed oil-ethyl ester (bio-diesel) were measured in the interval of 15–70 °C. The precision of the method described is better than ± 0.5 mg cm−3 at the temperature tolerance ± 0.1 °C.Článek Otevřený přístup peer-reviewedpublished A study of influence of alkali cations on dialysis rate of nickel(II) sulfate(Univerzita Pardubice, 1995) Handlířová, Marie; Macenauer, JaroslavThe dialysis rate of nickel(II) sulfate in a stirred bath dialyser through the cation exchange membrane Nafion 427 has been measured using aqueous solutions of alkali sulfates or sulfuric acid as a stripping solution. The influence of stirring velocity in the feed and stripping solutions on the transport rate of nickel(II) cations through the membrane has been studied. The individual values of dialysis coefficients of the membrane have been evaluated using the Wilson diagram. The time dependences of concentration of nickel(II) cations have been measured spectrophotometrically at the wavelength of 394 nm. It has been concluded that the dialysis coefficients KMj (j = H+, K+, Na+, Li+) of the membrane depend on the character of the cations and follow the order KMH+ > KMK+ > KMNa+ > KMLi+. This order does not agree with the expected reverse order of the radii of cations. The change in the order of cations is connected with the hydration number of the cations.Článek Otevřený přístup peer-reviewedpublished Erfahrung mit der ionenselektiven Bleielektrode Cryptur 82-17(Univerzita Pardubice, 1995) Svoboda, Ladislav; Schmidt, UweThe properties of a led ion-selective electrode Cryptur 82-17 after guaranteed lifetime were investigated and its suitability for kinetic and continuous measurements is discussed. The response of the electrode strongly depends on the ionic strength, composition and stirring intensity of the solution. Effect of pH in the pH range of 2–6 has not been observed. It is necessary from time to time to polish the surface of the electrode membrane because of the passivation. It is very important to know the electrode response time and the drift of its potential. The electrode can be recommended as an indication electrode for precipitation and complexometric titrations, whereas an application to direct, especially continuous potentiometric measurements is not advisable.Článek Otevřený přístup peer-reviewedpublished Computer simulation of bath dyeing of fibrous material(Univerzita Pardubice, 1995) Přikryl, Josef; Burgert, Ladislav; Akrman, JiříA mathematical model has been formulated for the dyeing process of a fibrous substrate in aqueous dyeing bath of finite ratio. The model has been constructed for the isothermal process kinetically controlled by the diffusion of dyestuff into the mass of fibre polymer for the case of nonlinear partition function of the dyestuff between the phases of fibre and bath. The numerical simulation by the Schmidt method of finite differences has been used to find the functions of concentration fields of dyestuff in cylindrical space of fibre and the transfer function of kinetic integral amount of dyestuff to fibre. The model has been formulated on the basis of dimensionless criteria of the theory of similarity. On the basis of the model suggested, the dimensionless criterial parameters have been found for the dyeing system which crucially affect the rate of dyestuff transfer from bath to fibre, the development of concentration field of dyestuff in fibre, and the degree of utilization of dyestuff in dyeing process. The results found can be applied in selecting and developing the dyestuffs for optimized and high-speed processes for the dyestuffs of disperse and reactive technological classes.Článek Otevřený přístup peer-reviewedpublished Determination of mean pore diameter of ceramic microfiltration membrane using retention characteristics(Univerzita Pardubice, 1995) Šedá, HanaMolecular weight cut-off experiments have been done to characterize alumina microporous membrane using PEG and dextran solutions. For the evaluation of the results, the final porous model was applied. The mass transfer coefficient was determined by the velocity variation method. The mean pore radius of the membrane used was estimated to be 60 nm, which corresponds well to the value obtained using the bubble-point technique.Článek Otevřený přístup peer-reviewedpublished Water transport properties of ceramic microfiltration membranes(Univerzita Pardubice, 1995) Mikulášek, Petr; Šedá, HanaThis paper deals with both theoretical and experimental study of the transport of water through α-alumina microfiltration membranes. A simple model combining the ideas of the capillary flow and the flow around solid bodies has been tested as a means for the precipitation of the hydraulic resistance in the flow of water through the ceramic membrane structure.