Kinetic theory of bridge processes

The detailed consideration of the kinetic aspect of the bridge process has allowed us to correctly write a kinetic equation beginning with knowledge of system microparameters. The solution of the equations makes it possible to elucidate the character of the relaxation process and to determine its typical constants as functions of those microparameters. Particular attention was given to kinetics in the presence of polaron effects. In this case the standard perturbation theory applied to derive the kinetic equations is not valid. The solutions obtained for this case are different both in the form of correlation functions and in the character of the interaction taken into account.     

Mitteilungen aus chemischen Gesellschaften

Ohne Zusammenfassung     

Discrete breathers in Fermi-Pasta-Ulam lattices

We study the properties of spatially localized and time-periodic excitations--discrete breathers--in Fermi-Pasta-Ulam (FPU) chains. We provide a detailed analysis of their spatial profiles and stability properties. We especially demonstrate that the Page mode is linearly stable for symmetric FPU potentials. A resonant interaction between a localized and delocalized perturbations causes weak but finite strength instabilities for asymmetric FPU potentials. This interaction induces Fano resonances for plane waves scattered by the breather. Finally we analyze the interplay between energy thresholds for breathers in the presence of strongly asymmetric FPU potentials and the corresponding profiles of the low-frequency limit of breather families.     

Über die anwendbarkeit der mikrotorsionswaage 1700 zur mikrogrammanalyse

The high precision of the Sartorius micro-balance 1700 with its load capacity of 2 g permits a weighing precision of ± 10 μg, which is the value of a half scale-division; by means of the classical “statistical weighing method”, an increased precision of ±1 μg is attainable. This accuracy is, in the investigated range, independent of the load up to 1.5 g.     

Beitrag zur Anwendung der Gel-Chromatographie in der Rückstandsanalyse,insbesondere am Beispiel der Bestimmung von Triazophos und Pyrazophos

The clean-up of the ethylacetate extracts of 31 common crops with the aid of liquid chromatography on polysterene gel is described. With a few exceptions, e.g. onions, the pesticide residue can be determined directly in the eluate gas-chromatographically using the electron capture or the flame photometric detector.     

Resonant light scattering by optical solitons

We consider the process of light scattering by optical solitons in a planar waveguide with homogeneous and inhomogeneous refractive index cores. We observe resonant reflection (Fano resonances) as well as resonant transmission of light by optical solitons. All resonant effects can be controlled in experiment by changing the soliton intensity.     

Calculation of the components of the photoelastic effect in alkali-halide crystals

Calculations are made to determine the contribution of Lorentz-field and Coulomb-field anisotropy in alkali-halide crystals to the photoelastic coefficients p₁₁–p₁₂ and p₄₄ as well as to the piezopolarizability constants K, K, K_x, K_z, and K₀. These calculations are based on Mueller's theory of the photoelastic effect, with data on iron polarizability and photoelastic coefficients. The applicability of Mueller' s theory to the complete series of alkali-halide crystals is analyzed. Criteria are established for the ionicity of bonds in these crystals.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 28–34, December, 1975.     

Die Bestimmung von Vanadiumspuren

Zusammenfassung Das Verhalten kleiner Vanadiummengen bei den gebräuchlichsten analytischen Operationen wird untersucht. Zur Abtrennung besonders geeignet erscheinen die Elektrolyse an der Hg-Kathode und das Ausschütteln der Vanadium-Hydroxychinolin-, der Kupferronoder der Dithiocarbamatverbindungen. Als Bestimmungsmethode wird die Polarographie in schwach alkalischem Boratpuffer wegen geringer Störungen und hoher Empfindlichkeit bevorzugt. Durch Kombination geeigneter, je nach Analysensubstanz auszuwählender Aufschluß-, Trennungs- und Bestimmungsmethoden lassen sich in praktisch allen vorkommenden Substanzen Vanadiumspuren bis herab zu etwa 10^–4%, in günstigen Fällen bis zu etwa 10^–7% quantitativ bestimmen. Durch Auswahl empfindlicherer Bestimmungsmethoden können möglicherweise noch kleinere Konzentrationen erfaßt werden.

---

Summary The behavior of slight amounts of vanadium in the ordinary analytical operations was studied. For separation, electrolysis on the Hg-cathode and extraction of the vanadium hydroxyquinoline- or dithiocarbamate compounds seem to be most suitable. As a method of determination, preference is given to polarography in weak alkaline borate buffer because of less interference and higher sensitivity. By combining suitable methods, to be selected according to the sample being analyzed, for the decomposition, separation, and determination, it is possible to make quantitative measurements, in practically all materials that will be met, of traces of vanadium down to around 10^–4%, in favorable instances to about 10^–7%. Even still lower concentrations might possibly be taken care of by selecting more sensitive determination methods.

---

Résumé Recherches sur le comportement de petites quantités de vanadium dans les opérations analytiques les plus courantes. Il apparaît que les méthodes de séparation les mieux appropriées sont l'électrolyse sur cathode de mercure et la précipitation sous forme de composés de l'hydroxyquinoléine, du cupferron ou du dithiocarbamate. La méthode de dosage la plus appropriée est la polarographie en tampon boracique faiblement alcalin car les effets perturbateurs y sont peu importants et la sensibilité en est très élevée. En associant, suivant la substance analysée, des méthodes choisies d'attaque, de séparation et de dosage, il est possible de déterminer des traces de vanadium pratiquement en présence de toutes substances jusqu'à une limite inférieure de 10^–4% qui peut être abaissée dans les cas favorables jusqu'à environ 10^–7 pour 100. Par le choix de méthodes de dosage plus sensibles, il est d'ailleurs possible de déterminer des concentrations encore plus faibles.

---

---

Wir danken Frl. A. Kratz und Herrn H. Oeser ffir ttilfe bei einem Teil der Versuehe.