Pionic and muonic X-ray transitions in liquid helium

Energies and intensities of pionic and muonic X-rays in liquid ⁴He have been measured with a Si (Li) detector. The energy shift due to strong interaction effects of the pionic 1s level in ⁴He was determined to be ?75.7±2.0 eV. The natural line width of this level is 45±3 eV. These values are compared with different theoretical predictions. Cascade calculations, including external Auger effect and sliding transitions, have been performed to reproduce the yields of the muonic and pionic transitions. The pionic 2p level width is deduced: $\text{Γ}{}_{\mathrm{<mtext>2</mtext><mtext>p</mtext>}}\text{= (1.1 ± 0.5) × 10}{}^{12}\text{sec}{}^{\mathrm{?1}}\text{=}\text{(7.2±3.3) × 10}{}^{\mathrm{?4}}\text{eV}$.     

Zur Synthese von 1-(3,3-Dimethyl-2-norbornyl)-äthanon

An improved synthesis of the title compound (1) is described. The catalytical action of variousLewis acids on the sterically hinderedDiels-Alder reaction of mesityl oxide with cyclopentadiene has been investigated. The mixture ofendo- andexo-isomers of the unsaturated intermediate2 yielded pure1 on hydrogenation and isomerization by sodium methoxide. The proof of theexo-configuration of the acetyl group has been achieved by mass spectra and 100 MHz¹H-NMR spectra.

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Herrn Prof. Dr.M. Pailer mit den besten Wünschen zum 65. Geburtstag gewidmet.     

Constantes de couplage vicinales à travers deux hétéroatomes: III—Calculs théoriques et mesures expérimentales dans les hydrazides enrichies en 15N

Different calculations, among them those utilizing the finite perturbation theory with INDO wave functions, have been effected to calculate the value of the ³J(¹H ? N? N? ¹H ) coupling constant in hydrazides as a function of the dihedral angle. Experimental coupling constants have been compared with calculated ones in order to determine the conformation around the N? N bond. The first example of a ²J(¹H ? N? ¹⁵N ) coupling is described.     

Reaktionsanalyse durch nichtisotherme Kalorimetrie: Lösungsreaktionen von Peroxiden,Ozoniden und Trioxiden

Homogeneous solution reactions (half-life-time for 1 M solutionsτ ₂₀° > ≈ 10^?4 sec, [ΔH] > 0.5 kcal/mole) have been investigated by non-isothermal differential calorimetry. By application of a new diagnostic procedure developed by use of an analogue computer, it can be decided whether the reactions of the substances tested are formal one-step processes, or what types of reaction-mechanisms must be considered. For the decompositions of some peroxide compounds the basic mechanism types, activation energies and action constants or entropies of the starting processes were determined. The cyclic furan ozonides have similar stabilities to that of the trioxide of di-isopropyl ether. On the other hand, triphenyl phosphite ozonide is considerably more unstable and can transfer oxygen to various acceptors below its decomposition temperature.     

On shortest cocycle covers of graphs

A cocycle (resp. cycle) cover of a graph G is a family C of cocycles (resp. cycles) of G such that each edge of G belongs to at least one member of C. The length of C is the sum of the cardinalities of its members. While it is known (see [5, 6]) that every bridgeless graph G = (V, E) has a cycle cover of length not greater than $\text{5}\text{3}\text{|E|}$, it is shown that there exists no α < 2 such that every loopless graph G = (V, E) has a cocycle cover with length not greater than α |E|. To do this, cocycle covers of minimal length are determined for the complete graphs, thus solving a problem stated at the end of [6].     

Sur une inegalite de H.P. Rosenthal et le theoreme limite central dans les espaces de Banach

This paper studies an inequality of H. P. Rosenthal for vector valued random variables, its relations with some geometric properties of Banach spaces and its applications to the study of the central limit theorem in Banach spaces.      

Septorine and N-methoxy septorine,substituted pyrazines from the fungus Septoria nodorum berk

On the basis of ¹H nmr correlations with synthetic analogs, structures $\text{1}$ and $\text{2}$ are proposed for septorine and N-methoxy septorine, two p-hydroxybenzoyl 1-isobutyl substituted pyrazines obtained from the fungus $\text{Septoria nodorum}$ Berk, a parasite of wheat.