INDO calculations on the sigmatropic [1, 5] H-Shift in 1,3-cyclohexadiene and 1,3,5-cycloheptatriene A homo-cyclopentadienyl transition state model

INDO calculations have been performed for the activated complex of the [1, 5] H.-shift in 1,3-cyclohexadiene and 1,3,5-cycloheptatriene. During the migration in the cyclohexadiene system a homoconjugation was calculated between the carbon atoms C₁ and C₅. For cycloheptatriene it could be demonstrated that one double bond does not participate in the reaction. Activation enthalpies are related to (homo)conjugation in the transition state of the reaction for cyclic conjugated dienes and trienes. The electron density on the migrating hydrogen can be related to the electron affinity of the ring system in the transition state.[/p]     

A microcomputer for the simultaneous data processing of different automatic elemental analysers

Summary A microcomputer has been developed for automated data processing of different automatic elemental analysers. The microcomputer allows users, already in possession of multimeters or integrators, an electronic microbalance and elemental analysers, to combine their equipment into an automated system. Depending on the elemental analysers available, it is possible with this system to determine simultaneously the elements C-H-N and O, C-H-N and S, or O and S, or it is also possible to determine these elements in duplicate. The microcomputer system is flexible and can easily be adapted for other applications by changing the software. After the analysers have been started, this system processes all data and calculates the blanks, calibration factors and percentages successively. The modes of operation of the principal parts of the microcomputer are described.

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Ein Mikrocomputer zur gleichzeitigen Datenverarbeitung verschiedener automatischer Elementaranalysengeräte

Zusammenfassung Ein Mikrocomputer zur automatischen Datenverarbeitung verschiedener automatischer Elementaranalysengeräte wurde entwickelt. Dieser ermöglicht, Vielfachmeßgeräte oder Zählgeräte, eine elektronische Mikrowaage und Analysengeräte zu einem automatischen System zusammenzuschließen. Je nach dem vorhandenen Analysator lassen sich damit C-H-N und O, C-H-N und S oder O und S gleichzeitig bestimmen oder man kann Doppelbestimmungen dieser Elemente durchführen. Das Mikrocomputer-System ist flexibel und kann durch Austausch der Soft-ware leicht für andere Zwecke adaptiert werden. Nach dem Start der Analysatoren verarbeitet dieses System alle Daten und berechnet die Leer werte, die Berechnungsfaktoren und die Prozentgehalte der Reihe nach. Die Arbeitsweise der Hauptteile des Mikrocomputers wurde beschrieben.

     

Single-crystal esr study of x-irradiated 2-chloro-2,2'-spirobis (1,3,2-benzodioxaphosphole): phosphorus in an octahedral geometry with the unpaired electron and chlorine in axial positions

X-irradiation of a single crystal of 2-chloro-2,2'-spirobis(1,3,2-benzodioxaphosphole) yields the oriented P^VI radical anion formed by electron capture. Directions of maximum values of the magnetic hyperfine tensors of ³¹P, ³⁵Cl, and ³⁷Cl are coincident and oriented along the P—Cl linkage, indicating an octahedral structure with the unpaired electron and chlorine in axial positions.     

Mechanical stresses in vapour quenched films of Al and Al rich compounds

The measurement of mechanical stresses in vapour quenched metal films can give additional structural information. Especially the near absence of stresses yields a sufficient condition for the formation of amorphous structures, since stress contributions due to the crystallite boundary mismatch are present in every micro crystalline film. From this point of view we find that Al films containing more than 25 at.% Ag grow in an amorphous phase whereas films with less than 25 at.% Ag are micro crystalline. The influence of other impurities, especially oxygen, is also investigated. Further evidence is presented for the high superconducting transition temperatures of Al films evaporated from Al₂O₃ crucibles, which films are micro crystalline, to be due to the presence of Al₂O impurities in these films.     

The inhibition of factor inhibiting hypoxia-inducible factor (FIH) by beta-oxocarboxylic acids

Cyclic beta-oxocarboxylic acids inhibit factor inhibiting hypoxia-inducible factor via ligation to the active site iron.     

A rutherford scattering study of the diffusion of heavy metal impurities in silicon to ion-damaged surface layers

Rutherford backscattering of 1.75 and 2 MeV ⁴He⁺ ions has been utilized to study the high temperature gettering of Fe, Co, Ni, Cu and Au from silicon by ion-damaged surface layers. In a typical experiment a metal film was evaporated onto one side of a silicon wafer (125 microm thick) which had received ion implantation damage (10¹⁶/cm² Si⁺ ions at 100 keV) on the opposite side; the wafer was then annealed at 900°C, usually for 30 min. The results of such experiments show that the metals studied may be divided into two classes, those which are gettered slowly - Fe, Co, and Au, and those gettered rapidly - Cu and Ni. Fe, Co, and Au were found at levels of 1×10¹³?1×10¹⁴/cm² in the damaged layer, whereas Cu and Ni appeared at levels of 6×10¹⁴ to 5 ×10¹⁶cm². The gettered level of Au, one of the “slow” group, was increased ten-fold by an equal increase in the anneal time to 300 min. The gettered Cu and Au exhibited double peaks in the scattered ion spectra, corresponding to metal concentrated at the most heavily damaged region (end of range for Si implant) and also at the outer surface, with a separation of ~ 1300 Å. A simple model is proposed to explain the slow and fast gettering, based on published interstitial diffusivities and solubilities of the five elements studied.Rutherford scattering has proven to be well suited for the quantitative identification of low levels of impurities on Si surfaces and for impurities gettered at damaged layers close to the surface.     

Dilute solution studies of nitrogen-substituted polyurethanes

A high molecular weight linear polyurethane was prepared by the polyaddition of equimolar amounts of ethylene glycol and methylene bis(4-phenyl isocyanate). Varying amounts of the labile carbamate protons of the polyurethane backbone were substituted by a number of groups of varying length and composition. The resultant grafted or nitrogen-substituted polyurethanes were then studied viscometrically in both polymer solvent and in a polymer solvent—nonsolvent mixture. The configuration of the nitrogen-substituted polyurethane was found to be dependent upon the number and length of pendent branches.