A 13C n.m.r. study of the charge-transfer complexes between o-chloranil and some aromatic electron donors

The ¹³C n.m.r. spectra of complexes between o-chloranil and aromatic electron donors were studied. Complexation leads to a general diamagnetic shift of the ¹³C n.m.r. signals for the acceptor (o-chloranil), but for signals from the ¹³C nuclei in the donors both diamagnetic and paramagnetic shifts are found. These phenomena are thought to be the result of competing anisotropy and charge-migration effects. Charge migration in o-chloranil complexes appears to be more important than in corresponding 1,3,5-trinitrobenzene complexes.     

Relativistic kinetic theory of quantum systems: III. Transport equation for a neutrino system

On the basis of the quantum-mechanical equations of motion and the statistical assumption that dynamical correlations present in the initial state may be ignored, a kinetic equation for a dilute neutrino system is derived. If the system is sufficiently uniform in space this equation reduces to the relativistic Boltzmann equation for massless particles with a quantum-mechanical transition probability.     

Values for the transport coefficients of a neutrino-antineutrino system

The transport coefficients of a neutrino-antineutrino mixture are calculated numerically in successive orders of approximation for various compositions of the system. A cosmological application is suggested.     

The level structure of 90Mo

High-spin states of the N = 48 nucleus ⁹⁰Mo have been studied using the 33 MeV ⁹⁰Zr(³He, 3nγ) reaction. A previously unknown level structure above the 8⁺ isomer and several new lower-lying levels have been identified. The results are discussed in terms of shell-model calculations which allow four protons in the $\text{2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{and}\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ subshells and two neutron holes in the $\text{1}\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{, 2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{, 2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{,}\text{or}\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ orbitals.     

The problem of the azatropylium ion: Hydrogen elimination from the molecular ion of γ-picoline

Comparison of the mass spectrum of γ-picoline with that of analogues, specifically deuterated in the methyl group, the ring or both, has shown that the molecular ion loses the α,β and methyl hydrogen atoms (ω-hydrogen') in the ratio 1.43: 1: 1. 13. The same trend is found for the elimination of HCN from the molecular ion. Moreover, a value of 1.52 is found for the isotope effect, expressing the favoured loss of H over D, irrespective of its position.     

Zur Theorie der viskoplastischen Stoffe

Zusammenfassung Für viskoplastische Stoffe wird eine modifizierte Stoffgleichung der bekannten Ansätze von Perzyna [1] vorgeschlagen. Mit dieser Stoffgleichung gelingt es bei relativ langsam viskoplastischem Fließen die Eindeutigkeit der Lösungen nachzuweisen und zwei Extremalprinzipe anzugeben, die es gestatten, den wirklichen Spannungs- und Verzerrungsgeschwindigkeitszustand einzuschränken.

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Summary A modified form of the well-known equations from Perzyna [1] for viscoplastic material is presented. With these modified equations, one can prove the uniqueness of the solution and derive extremum principles for the problems having slow viscoplastic flow. Using these extremum principles, the upper and lower bounds for the actual stresses and the rate of change of strains can be given.