Residual entropy of the one-dimensional Ising antiferromagnet with general spin

We have calculated the ground-state degeneracy and the concominant residual entropy of the one-dimensional Ising antiferromagnet in a critical magnetic field. We demonstrate that the results obtained can be related to the ground-state properties of the q-state Potts antiferromagnet in the corresponding external field.     

Non-uniqueness of the heat current operator and the hopping thermoelectric and Nernst-Ettingshausen effects in amorphous semiconductors

The Hardy correction in the heat current operator is generalized to the case of non-zero electron-phonon coupling constantg. It is then shown that not only the lowest (minus first) order but also the fist order contribution ing to the thermoelectric power of amorphous semiconductors in the hopping regime disappears. Consequently, since the lowest (zero) order contribution to the thermoelectric effects in the magnetic field yields no Nernst-Ettingshausen effect in these materials, the last effect is of the second order ing, at least.     

A model of structure periodically modulated in three dimensions

A model of structure periodically modulated in three dimensions is calculated in the presented paper and applied to the alloy Cu₈₀Au₂₀. The existence and intensity of the side-bands of the Bragg lines appearing with hyperstructural lines on films of this alloy after heating to temperature on the border of the order-disorder transformation are explained by means of the given model and the value of the period of sinusoidal variation of the lattice parameter and scattering power is calculated.ikova 22, Brno, Czechoslovakia.The author thanks Mrs. V. Gregor and Mr. M. Jelínek who prepared the necessary pictures.     

The syn and anti Steric Course in Bimolecular Olefin-Forming Eliminations

Earlier evidence led to the view that in bimolecular olefin-forming eliminations the anti steric course is generally preferred over the syn. Recent experiments, however, show that in some common bimolecular elimination reactions, notably those involving onium bases, syn- and anti-eliminations proceed side by side, the former preferentially leading to the trans- and the latter to the cis-olefins.     

Analysis of finite element methods for second order boundary value problems using mesh dependent norms

This paper presents a new approach to the analysis of finite element methods based onC ⁰-finite elements for the approximate solution of 2nd order boundary value problems in which error estimates are derived directly in terms of two mesh dependent norms that are closely ralated to theL ₂ norm and to the 2nd order Sobolev norm, respectively, and in which there is no assumption of quasi-uniformity on the mesh family. This is in contrast to the usual analysis in which error estimates are first derived in the 1st order Sobolev norm and subsequently are derived in theL ₂ norm and in the 2nd order Sobolev norm — the 2nd order Sobolev norm estimates being obtained under the assumption that the functions in the underlying approximating subspaces lie in the 2nd order Sobolev space and that the mesh family is quasi-uniform.     

Arc plasma in air with calcium and fluorine—I. Calculation of the plasma composition

The equilibrium composition of the gaseous system containing N, O, C, F and Ca was calculated in the temperature range between 298 and 7000 K. This gas mixture corresponds to the plasma of a d.c. low current arc freely burning in the air between graphite electrodes in the presence of fluorine and calcium.     

Polarometrische Bestimmung von Methylenblau mit Phosphorwolframsäure

Zusammenfassung Ein Mol Phosphorwolframsäure reagiert in 2,5M Salzsäure mit 5 Mol Methylenblau unter Bildung eines Niederschlages, der in Wasser und verdünnten Mineralsäuren unlöslich ist. Diese Reaktion wurde zur polarometrischen Bestimmung von Methylenblau benützt. Bei Einhaltung aller Versuchsbedingungen, besonders der Acidität der Lösung, sind die Resultate gut. Der Äquivalenzpunkt der Titration wurde unter Verwendung einer modifizierten Rechenmethode bestimmt.

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Polarometric determination of methylene blue with phosphotungstic acid

Summary One mol phosphotungstic acid reacts in 2.5M hydrochloric acid with 5 mol Methylene Blue creating a precipitate insoluble in water and in diluted mineral acids. The given reaction was applied for the polarometric determination of Methylene Blue. Under keeping of all experimental conditions, especially of the solution acidity, the results are good. The equivalence point of the titration was determined using a modified method of calculation.