Optische Rotationsdispersion und Circulardichroismus bei Jod-Polysaccharid-Komplexen

Zusammenfassung Die wäßrigen Lösungen der Jodkomplexe von Stärke, verschiedenen Amylosen und Amylopektinen zeigen im Bereich der betreffenden Absorptionsmaxima einen induzierten positiven Cotton-Effekt. Die Drehwerte hängen in der gleichen Weise vom Jod-Amylose-Verhältnis ab wie die Extinktionen bei 660 und 445 m. Die Drehwerte einiger Jod-Polysaccharid-Komplexe nehmen mit der Zeit stark zu, obwohl die Extinktion konstant bleibt. Maßnahmen, durch welche die Struktur der Jod-Einschlußverbindung verändert wird (Erwärmung, Zusatz von Salzen, Lösungsmitteln, Harnstoff, Netzmitteln) haben einen starken Einfluß auf den induzierten Cotton-Effekt.

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Summary Aqueous solutions of iodine complexes with starch, different samples of amylose or amylopectin show an induced positive Cotton effect in the region of the absorption maximum. The rotatory power and the extinction at 660 and 445 m depends upon iodine amylose ratio. The optical of some complexes increases with time, whereas the absorption remains constant. Experimental conditions which change the structure of the channel complexe (heating, addition of salts, solvents, urea or detergents) influence the induced Cotton effect.

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Mit 8 Abbildungen in 9 Einzeldarstellungen und 1 Tabelle

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2. Mitt. J. macromol. Sci. Chem.A2 im Druck; 1. Mitt.R. Wolf undR. C. Schulz, Tetrahedron Letters1967, 1799.

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Vortrag anläßlich der 23. Arbeitstagung der Kolloid-Gesellschaft in Bad Oeynhausen 27. 10. 1967.

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Auszug aus der Dissertation vonH. Mayerhöfer, Mainz 1967, D. 77.     

Zur Ermittlung von Diffusionskoeffizienten in Festkörpern aus Sorptionsdaten

Zusammenfassung Für die Ermittlung von Diffusionskoeffizienten in Festkörpern aus Sorptionsdaten wurden die in der Literatur angeführten Näherungslösungen des zweitenFickschen Diffusionsgesetzes hinsichtlich ihrer Genauigkeit und ihrer Gültigkeitsbereiche untersucht. Dabei konnten zwei weitere Näherungslösungen mit größerer Genauigkeit abgeleitet werden. Zur Berechnung der Diffusionskoeffizienten wurde der ZeitparameterDt/r ² als Funktion vom Umsetzungsgrad mit einer relativen Genauigkeit von 0,001 (auch im Falle der Interpolation) tabelliert. Weiterhin werden einige graphische Verfahren zur Bestimmung des Diffusionskoeffizienten vorgeschlagen und deren Anwendungsmöglichkeiten diskutiert.

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Summary In order to determine the diffusivities in solids from sorption data, the approximation solutions of the secondFick's law as cited in literature have been investigated with regard to their accuracy and validity range. Two new approximation solutions showing a greater accuracy have been derived. With a view to compute the diffusivities, the time parameterDt/r ² has been tabulated as a function of the fractional attaintment of equilibrium, with a relative precision of 0.001 (also in the case of interpolation). Furthermore some graphic procedures for the determination of the diffusivities are proposed and their applicabilities are discussed.

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Mit 8 Abbildungen und 7 Tabellen     

Interdependence of enthalpic and entropic contributions to the second osmotic virial coefficient

The interdependence of the enthalpic contribution A_{2, H} and the entropic contribution A_{2, s} to the second osmotic virial coefficient for a given polymer-solvent system has been investigated from the experimental and the theoretical point of view. Experimentally, the following common facts were observed for various systems at temperatures and pressures below the critical values for the solvent. Both the isobaric and isothermal dependences can be approximated over relatively wide ranges of A_{2, H} by linear relations with a slope deviating only slightly, but in a characteristic manner from a value of ?1. When the temperature is increased at constant pressure one moves along an isobar towards higher A_{2, H}; when the pressure is increased at constant temperature, one moves along an isotherm in the opposite direction, i.e., towards lower A₂, _H. Theoretically this behavior can be described in a qualitative manner, starting from a relation derived by Patterson and Delmas on the basis of the Prigogine corresponding-states theory. The reasons for the lack of quantitative agreement are discussed.     

Inclusive Δ++ production in K+p interactions at 8.2 and 16 GeV/c

The reaction K⁺p→Δ⁺⁺(1236)+ anything is studied at beam momenta 8.2 and 16 GeV/c and compared with other Δ⁺⁺ producing reactions. We find that the low-mass Δ⁺⁺π^? enhancement affects the shapes of Δ⁺⁺ inclusive distributions. The triple-Regge formula is found to be consistent with the data. Dual properties of this formula are successfully tested.     

Dissipation,mass exchange and the microscopic time scale of heavy-ion collisions

The time scale provided by the nucleon exchange mechanism in heavy-ion reactions is employed to study kinetic energy damping. The experimental kinetic energy lost per nucleon exchanged in Kr- and Xe-induced reactions is observed to decrease linearly with the total kinetic energy loss. These results, which are consistent with energy dissipation and nucleon exchange occuring on a similar time scale, are compared with the predictions of a one-body dissipation mechanism and a diffusion model.     

Measurement of the reactions K+d → K+d and K+d → p+pn and an investigation of elastic K+-nucleon scattering at 4.6 GeV/c

The coherent elastic reaction K⁺d → K⁺d and the break-up reaction K⁺d → K⁺pn are studied in a K⁺d experiment at 4.6 GeV/c which the CERN 2 m bubble chamber. Partial and differential cross sections are given and the slopes of the differential cross sections are determined. The results for the reaction K⁺d → K⁺p(n_s), where n_s denotes the spectator neutron, are compared with those of the reaction K⁺p → K⁺p on free protons. Combining our data with existing data on the reactions K⁺d → K⁰pp and K⁺p → K⁺p, parameters of the elastic K⁺-nucleon scattering at 4.6 GeV/c are determined in the framework of the Glauber model. The D-wave of the deuteron and spin-flip effects are taken into account.