Some aspects of element distribution inBetula alba, a contribution to representative sampling of terrestrial plants for multi-element analysis

Summary The leaves of six differently aged birch trees (Betula alba), growing under slightly varying soil conditions, were collected representatively. The elements Ca, K, Mg and Zn were determined by different analytical methods (AAS and AES/ICP). The data sets obtained were in good agreeent with each other. The biological variances of Al, Ba, Ca, Cu, Fe, K, Mg, P and Zn between leaves of different trees were less than 30%, with the exception of phosphorus (38%). Ca, K, Mg, Mn and Zn show an increase of between 50%–70% depending on the height of the trees. The developed sampling procedure (5–10 trees per ecosystem) can be adapted to produce a representative sampling design on population level.

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Einige Aspekte der Elementverteilung inBetula alba, ein Beitrag zur repräsentativen Probenahme von terrestrischen Pflanzen für die Multielement-Analyse

     

Die Synthese von 3β-Acetoxy-24-aza-24-desoxa-xysmalogenin,. Partialsynthetische Versuche in der Reihe der Herzgifte. 12. Mitteilung,

Synthesis of 3β-acetoxy-24-aza-24-desoxa-xymalogenin Starting from the pregnenolone-derivative 1 we report the synthesis of the possibly cardiac-active compound 24-aza-24-desoxa-xysmalogenin 15 .     

Theoretical investigation of the cyclic conformer of ozone

Ab initio SCF and CI calculations are reported which find the cyclic conformer of ozone to lie 16 kcal/mole above the preferred (open-chain) form of this substance. Polarization functions in the AO basis set are found to be quite important in this determination, strongly favoring the cyclic species. The possible experimental significance of such a relatively stable ring conformer of ozone is assessed.     

Aluminium

Ohne Zusammenfassung     

Calculation of wavefunctions and frequencies for noninfinitesimal vibrations: Comparison of various methods using ab initio CI potential curves

Three computational methods employing different means of representing molecular potentials are used to obtain wavefunctions and energy levels for noninfinitesimal vibrations. An interpolation scheme based on a cubic spline fitting procedure is introduced to supplement the CI energy results obtained explicitly in actual calculations. As long as a representative set of potential points is available it is found that the results of all three methods (two of variational and one of numerical integration type) are quite consistent, for both bending and stretching vibrations of ground and electronically excited states (examples for HCN and O₂ are considered). In addition a comparison of one- and two-dimensional bending vibrational treatments is made.