Biosynthesis of iso-fatty acids in myxobacteria: iso-even fatty acids are derived by alpha-oxidation from iso-odd fatty acids

The biosynthesis of iso-fatty acids was investigated in the myxobacteria Myxococcus xanthus and Stigmatella aurantiaca by feeding labeled precursors of these fatty acids and by conducting detailed analysis of the fatty acid profiles and fatty acid MS and NMR spectra. These experiments revealed that in S. aurantiaca all iso-even fatty acids are formed via alpha-oxidation of iso-odd fatty acids and not by using valine-derived isobutyryl-CoA.     

Unnatural-parity states in 44 21Sc23

The neutron-deficient nucleus ⁶⁸As was populated at high spin in two experiments using the reaction ⁴⁰Ca(³²S, 3pn) at beam energies of 105 and 95 MeV. A self-supporting and a gold-backed, highly enriched ⁴⁰Ca target were used. Gamma rays were detected with the EUROBALL array, combined with the charged-particle detector array EUCLIDES and the Neutron Wall. The ⁶⁸As level scheme was considerably extended, especially at negative parity and many previous spin-parity assignments were confirmed or rejected. The total-Routhian-surface (TRS) calculations find shape coexistence and softness for the negative- and positive-parity states, respectively.     

Synthese und Eigenschaften einiger h?hergliedriger cyclischer Atheracetale

Ohne Zusammenfassung     

An example of a cubic graph with two orbits and simple eigenvalue √3

The question whether there exist cubic graphs with two orbits and simple eigenvalues ±√3 is answered in the affirmative; the minimum number of vertices of such graphs is equal to 32.     

Das System Wolfram/Iod

The System Tungsten/Iodine The compounds W₆I₁₂, W₆I₁₄, W₆I₁₅, W₆I₁₇ and WI_3,3(W₆I₂₀?) are prepared. Lattice constants for W₆I₁₂ and W₆I₁₅ are given. WI_3.00 is prepared by synthesis from the elements or by transport of WI_3.3. It is deposited at 350°C. The chemical transport of WI_3.00 (450 ° 350°C) in the presence of I_2.g leads to the formation of small quantitites of WI_3.00 (350°C) and of a residue of W₆I₁₂.     

Phase-distribution chromatography (PDC) of polystyrene

A chromatographic technique is described where the stationary phase is a layer of a very high molecular polystyrene fraction (M = 10⁷) on glass beads (ballotines). The mobile phase is cyclohexane passing the column at a constant temperature below the theta-temperature. A polystyrene sample of sufficiently low molecular weight (M ≤ 10⁶) injected as a small plug at the top of the column is fractionated because the distribution between the mobile and the stationary phase depends on the molecular weight. Since the large molecules preferentially remain in the stationary phase, the smaller molecules leave the column first. The fractionation effect is inverse to that found in GPC experiments. The separation efficiency is rather good and can be described by a simple thermodynamic theory.