On the Hahn--Mazurkiewicz theorem

The following generalization of the Hahn-Mazurkiewicz theorem is proved: Let (E,e) be a locally compact locally connected metric space. Let M be a continuum in this space and let d,e∈ M. Then there is a continuous mapping f: [0,1]→E such that f(0) = d, f(1)= e and M⊂f([0,1]). Also some corollaries of this theorem are proved.     

Measurability implies continuity for solutions of functional equations - even with few variables

Summary. We prove that - under certain conditions - measurable solutions $f$ of the functional equation $f(x)=h(x,y,f(g_{1}(x,y)),\ldots,f(g_{n}(x,y))),\quad(x,y)\in D \subset \mathbb{R}^{s} \times \mathbb{R}^{l}$ are continuous, even if $1\le l\le s$. As a tool we introduce new classes of functions which - roughly speaking - interpolate between continuous and Lebesgue measurable functions. Connection between these classes are also investigated.     

Assignment of the EPR spectrum of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) superoxide spin adduct

[structure: see text] Spin trapping consists of using a nitrone or a nitroso compound to "trap" an unstable free radical as a long-lived nitroxide that can be characterized by electron paramagnetic resonance (EPR) spectroscopy. The formation of DMPO-OOH, the spin adduct resulting from trapping superoxide (O(2)(*)(-)) with 5,5-dimethyl-1-pyrroline N-oxide (DMPO), has been exploited to detect the generation of superoxide in a wide variety of biological and chemical systems. The 12-line EPR spectrum of DMPO-OOH has been either reported or mentioned in more than a thousand papers. It has been interpreted as resulting from the following couplings: A(N) approximately 1.42 mT, A(H)beta approximately 1.134 mT, and A(H)gamma(1H) approximately 0.125 mT. However, the DMPO-OOH EPR spectrum has an asymmetry that cannot be reproduced when the spectrum is calculated considering a single species. Recently, it was proposed that the 0.125 mT splitting was misassigned and actually results from the superimposition of two individual EPR spectra associated with different conformers of DMPO-OOH. We have prepared 5,5-dimethyl-[3,3-(2)H(2)]-1-pyrroline N-oxide (DMPO-d(2)), and we showed that the EPR spectrum of the corresponding superoxide spin adduct is composed of only six lines, in agreement with the assignment of the 0.125 mT splitting to a gamma-splitting from a hydrogen atom bonded to carbon 3 of DMPO. This result was supported by DFT calculations including water solvation, and the asymmetry of the DMPO-OOH EPR spectrum was nicely reproduced assuming a chemical exchange between two conformers.     

Evaluation of cyclodextrin polymer as a disintegrating agent

Cyclodextrin polymer was compared to other well known disintegrants concerning the swelling properties /water uptake, moisture uptake, hydration capacity, sedimentation volume in water/. Its high disintegrating effect was proved in directly compressed tablets as well as in tablets made by wet granulation. A remarkable improvement in tablet properties was observed. Not only the disintegration of tablets and the dissolution of the drug was accelerated but also the hardness increased when CDP was used as disintegrant.     

Bestimmung des Osmiums auf katalytischer Grundlage mittels einer Photokomparationsmethode

Zusammenfassung Auf Grund seiner katalytischen Wirkung auf die Lumineszenzreaktion von Luzigenin mit Wasserstoffperoxid läßt sich Osmiumtetroxid im Konzentrationsbereich von 1 bis 60g/5 ml mit Hilfe der Simultan-komparationsmethode hinreichend genau bestimmen. Die störenden Ionen des Cu, Cd, Pb, Hg, Co, Ni, Ca und Mg lassen sich mit ÄDTA maskieren.

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Summary Osmium tetroxide can be detected in the concentration range of 1 to 60g/5 ml through its luminescence reaction with hydrogen peroxide and lucigenin with sufficient precision by means of the simultaneous comparation method. The interfering ions (Cu, Cd, Pb, Hg, Co, Ni, Ca, and Mg) can be masked with EDTA.

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Résumé En utilisant l'action catalytique du tétroxyde d'osmium sur la réaction de luminescence de la lucigénine avec l'eau oxygénée, on peut le doser avec suffisamment de précision dans le domaine des concentrations allant de 1 à 60g/5 ml par la méthode de comparaison photométrique. On peut masquer par l'EDTA les ions gênants de Cu, Cd, Pb, Hg, Co, Ni, Ca et Mg.

     

Particle-size analysis of latexes by classical and small-angle spectrodissymmetry

The spectral dependence of classical and small-angle dissymmetryZ in polydispersions containing spherical particles with lognormal distribution was theoretically studied. It has been found, for instance, for polystyrene latex that small-angle dissymmetry may be used for determining the distribution parameters in systems with particle medial radius 60–700 nm on the basis of measurements ofZ (10°/5°( at two wavelengths of radiation. For particles outside this interval and by use of working relationships of classical dissymmetry only the application of a wide range of wavelengths comes into consideration by distribution analysis.     

Bestimmung von Ascorbinsäure auf Grund ihrer in einem Landolt-System ausgeübten reduzierenden Wirkung

Zusammenfassung Im Bromat-Jodid-Ascorbinsäure-System hängt die Zeit, die bis zur Jodausscheidung vergeht, von der Konzentration der Ascorbinsäure ab. Unter entsprechenden Versuchsbedingungen ist die Reaktionszeit proportional der Ascorbinsäurekonzentration. Danach kann die Ascorbinsäure sowohl mit Hilfe der Simultankomparationsmethode, als auch chronometrisch bestimmt werden. Die Genauigkeit ist ± 3% im Bereich von 5 bis 300g/5 ml. Die Grenzen der Bestimmung sind 1g bzw. 1000g Ascorbinsäure in 5 ml.

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Determination of ascorbic acid on the basis of its reducing action in a landolt system

Summary In the bromate-iodide-ascorbic acid system, the time that elapses until the iodine appears is dependent on the concentration of the ascorbic acid. Under appropriate experimental conditions, the reaction time is proportional to the ascorbic acid concentration. Accordingly, the ascorbic acid may be determined with the aid not only of the simultaneous comparison method but also chronometrically. The precision is ± 3% in the 5–300g/5 ml range. The limits of the determination are 1g and 1000g ascorbic acid in 5 ml respectively.

     

Coordination modes between copper(II) and N-acetylneuraminic (sialic) acid from a 2D-simulation analysis of EPR spectra. Implications for copper mediation of sialoglycoconjugate chemistry relevant to human biology

The equilibrium distribution of species formed between Cu(II) and N-acetylneuraminic (sialic) acid (I, LH) at 298 K has been determined using a two-dimensional (2D) simulation analysis of electron paramagnetic resonance (EPR) spectra. In acidic solutions (pH values < 4), the major species present are Cu(2+), [CuL]+ [logbeta = 1.64(4)], and [CuL2] [logbeta = 2.77(5)]. At intermediate pH values (4.0 < pH < 7.5), [CuL2H-1]- [logbeta = -2.72(7)] and two isomers of [CuLH-1] [logbeta (overall) = -3.37(2)] are present. At alkaline pH values (7.5 < pH < 11), the major species present is [CuL2H-2]2-, modeled as three isomers with unique giso and Aiso values [logbeta (overall) = -8.68(3)]. Two further species ([CuLH-3]2- and [CuL2H-3]3-) appear at pH values > 11. It is proposed that [CuL]+ most likely features I coordinated via the deprotonated carboxylic acid group (O1) and the endocyclic oxygen atom (OR) forming a five-membered chelate ring. Select Cu(II)-I species of the form [CuLH-1] may feature I acting as a dianionic tridentate chelate, via oxygen atoms derived from O1, OR, and one deprotonated hydroxy group (O7 or O8) from the glycerol tail. Alternatively, I may coordinate Cu(II) in a bidentate fashion as the tert-2-hydroxycarboxylato (O1,O2) dianion. Spectra predicted for Cu(II)-I complexes in which I is coordinated in either a O1,OR {I1-} or O1,O2 {I2-} bidentate fashion {e.g., [CuL]+ (O1,O R), [CuL2] (bis-O1,O R), [CuLH-1] (isomer: O1, O2), [CuL2H-1]- (O1, O R; O1, O2), and [CuL2H-2]2- (isomer: bis-O1, O2)} have "irregular" EPR spectra that are ascribed to the existence of Cu(II)-I(monomer) <==> Cu(II)-I(polymer) equilibria. The formation of polymeric Cu(II)-I species will be favored in these complexes because the glycerol-derived hydroxyl groups at the complex periphery (O, 7O, 8O9) are available for further Cu(II) binding. The presence of polymeric Cu(II)-I species is supported by EPR spectral data from solutions of Cu(II) and the homopolymer of I, colominic acid (Ipoly). Conversely, spectra predicted for Cu(II)-I complexes where I is coordinated in a {I2-} tridentate {e.g., [CuLH-1] (isomer: O1, O R, O7, or O8) and [CuL2H-2]2- (isomer: bis-O1,O R,O7, or O8)} or tetradentate fashion {I3-} {e.g., [CuLH-3]2- (O1, O R, O, 8O9)} are typical for mononuclear tetragonally elongated Cu(II) octahedra. In this latter series of complexes, the tendency toward the formation of polymeric Cu(II)-I analogues is small because the polydentate I effectively wraps up the mononuclear Cu(II) center. This work shows that Cu(II) could potentially mediate the chemistry of sialoglycoconjugate-containing proteins in human biology, such as the sialylated amyloid precursor protein of relevance to Alzheimer's disease.     

Die katalytischen Reaktionen bei der Spurenanalyse und die Untersuchung ihrer Mechanismen. II Untersuchung der Tiron—H2O2-Reaktion

Zusammenfassung Die Oxydation von Tiron durch H₂O₂ in basischem Milieu wird durch Kobalt stark katalysiert. Die katalysierten Vorgänge sind p_H-abhängig. Im p_H-Bereich 9 bis 11 entsteht ein rotes Oxydationsprodukt unbekannter Struktur; wahrscheinlich handelt es sich um ein o-Chinonderivat. Mit Hilfe der katalytischen Reaktion können 10^–4 g Kobalt/5 ml nachgewiesen werden. In diesem p_H-Bereiche stabilisiert Tiron H₂O₂ bei 100° C, bei 40° C jedoch katalysiert es — in Abhängigkeit von der Konzentration des Tirons — den Zerfall des H₂O₂. Der Effekt spielt im Mechanismus der katalysierten Reaktion wahrscheinlich eine Rolle, doch können die Zusammenhänge an Hand der bisher veröffentlichten Angaben nicht klar gedeutet werden. Der die Reaktion begleitende bzw. ihr folgende Nebenvorgang kann auf den katalytischen Zerfall des H₂O₂ · OOH-Komplexes zurückgeführt werden. Zwischen p_H 7 und 9 entsteht bei der katalysierten Reaktion Semichinon, über p_H 11 oxydiert Tiron das Semichinon unter Ringspaltung und Abspaltung von 1 Mol Sulfat zu Verbindungen, die Säurecharakter tragen.

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Summary The oxidation of Tiron by H₂O₂ in basic milieu is strongly catalyzed by cobalt. The catalyzed reactions are p_H-dependent. A red oxidation product of unknown structure results in the p_H range 9 to 11; probably it is ano-quinone product. As little as 10^–4 g cobalt/5ml can be detected by this catalytic action. In this p_H region, Tiron stabilizes H₂O₂ at 100° C, but at 45° C it catalyzes the decomposition of H₂O₂, in relation to the concentration of the Tiron. The effect probably plays a rôle in the mechanism of the catalyzed reaction, but the up to now published informations are not sufficient to clarify the relationships. The auxiliary process, accompanying or following the reaction, can be attributed to the catalytic decomposition of the H₂O₂-OOH^– complex. Semiquinone is produced by the catalytic reaction between p_H 7 and 9, above p_H 11, the Tiron oxidizes the semiquinone with opening of the ring and splitting off of 1 mol of sulfate yielding compounds which have an acidic character.

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Résumé L'oxydation du Tiron par H₂O₂ en milieu basique est fortement catalysée par le cobalt. Les processus de catalyse dépendent du p_H. Dans le domaine de p_H de 9 à 11, il apparaît un produit d'oxydation rouge, de structure inconnue; il s'agit probablement d'un dérivé de l'o-quinone. La réaction catalytique permet de déceler 10^–4 g cobalt/5 ml. Dans ce domaine de p_H, à 100° C le Tiron stabilise l'eau oxygénée et à 45° C, suivant sa concentration, il catalyse la décomposition de l'eau oxygénée. L'effet joue probablement un rôle sur le mécanisme de la réaction catalysée; on ne peut pourtant pas interpréter clairement ces relations au moyen des indications publiées jusqu'ici. Le processus secondaire qui accompagne la réaction ou qui la suit, peut être ramené à la décomposition catalytique du complexe H₂O₂-OOH^–. Entre p_H 7 et 9, la réaction catalysée donne naissance à une semiquinone; au-dessus de p_H 11, le Tiron oxyde la semi-quinone avec ouverture du cycle et élimination d'une mole de sulfate ce qui donne ensuite des composés qui portent le caractère acide.

     

Encapsulation of magnetite in vesicles

The encapsulation of fine magnetite particles of 10 nm size and marker ANS within asolectin vesicles has been made by sonication of the mixture in water. For the proof of encapsulation of magnetite in vesicles the electron microscope and spectrofluoriphotometer technique were used. The theory for the calculation of the magnetic force acting on the system consisted of non-capsulated magnetic particles dispersed in water and magnetic vesicles was developed.This work was supported by the Slovak Academy of Sciences within the framework of Project GAV No. 1361.