Ein Cohen-Macaulay-Kriterium mit Anwendungen auf den Konormalenmodul und den Differentialmodul

Ohne Zusammenfassung     

Der Zerfall des94Sr

The nuclide⁹⁴Sr was isolated by chemical separation methods after thermal neutron induced fission of²³⁵U. Its decay properties were investigated employing semi-conductor spectrometers and coincidence techniques. A half-life of 74.1±0.3 sec was found. Besides the 1428.3 keV γ-ray we found 4 new γ-rays which could be placed in a decay scheme comprising three excited states of⁹⁴Y. The 1⁺ states in theuu-nuclides^90,92,94Y and^88,90,92Rb are compared.     

Certain complexes associated to a sequence and a matrix

Let R be a commutative noetherian ring with unit. To a sequencex:=x₁,...,x_n of elements of R and an m-by-n matrix α:=(α_ij) with entries in R we assign a complex D*(x;α), in case that m=n or m=n?1. These complexes will provide us in certain cases with explicit minimal free resolutions of ideals, which are generated by the elements a_i:=∑α_ijx_j and the maximal minors of α.     

Coupling of HPLC and NMR 1—analysis of flowing liquid chromatographic fractions by proton magnetic resonance

A procedure is described which allows the recording of ¹H NMR spectra from high performance liquid chromatography (HPLC) fractions flowing through the magnetic field with a velocity of either 0.05 or 0.25 cm/s. The NMR spectra are obtained by the pulse Fourier transform technique; the beginning and the termination of the pulse sequence is timed according either to the chromatogram from a UV detector or to the free induction decay of the appropriate HPLC fraction. The linewidth of the signals in the NMR spectra is between 1.5 and 2.0 Hz.     

Semi-empirical molecular orbital calculations for pyridinealdoximes and acetamidopyridines

Tautomerism of pyridinealdoximes and acetamidopyridines is discussed with regard to their electronic absorption spectra. The spectra of both neutral and ionic forms of the molecules are interpreted by means of the Pariser—Parr—Pople type of calculation in a satisfactory way.The stability of 2- and 4-pyridinealdoxime tautomers is investigated using the CNDO/2 method. The lactim are more stable than the lactam forms of the molecules. The molecules having the substituent group of the syn-configuration are more stable than the molecules with other configurations of the substituent.     

Quantification of hydroxylic groups in a river humic substance by 29Si-NMR

Quantification of the hydroxylic functions of carboxylic, phenolic and alcoholic groups in a selected river humic substance (Ruhr/Germany) is performed by methylation/silylation and ²⁹Si-NMR analysis. The well known methylation/silylation procedure of Thorn et al. is modified by carrying out the diazomethane methylation in the presence of the proton catalyst p-toluene sulphonic acid. Additional experiments by both ¹³C-NMR-spectroscopy and potentiometric acid-base titration confirm the results obtained by ²⁹Si-NMR.