Ein supraleitender Gleichrichter und Verstärker

Ohne Zusammenfassung     

On the superconductivity in β-beryllium and related phases

Two high temperature beryllium allotropes have been stabilized at room temperature through the addition of transition elements. Superconductivity has been observed in almost all of them. Beryllium films reported superconducting in the past appear in all probability to require the presence of transition element impurities, in order to show the phenomenon.     

Technology showcase electronic penetrometer for field tests

The design and construction of a cone penetrometer for field use is described. The penetrometer is mounted on a frame to which two wheels are fitted for towing the device from one test site to the next. An electric motor drives the penetrometer during the test and simultaneous readings are performed of both cone depth and penetration resistance. The device weighs 70 kg and the maximum force on the cone typically exceeds 1.2 kN. The acquired data are transferred to a microcomputer and after each penetration the result is presented to the operator in graphic form. The microcomputer is equipped with a fairly large RAM memory which serves as storage medium for data during measuring work. Afterwards, data are easily moved to a mainframe computer for analysis.     

Electron-transfer reactions and conformational changes associated with the reduction of substituted bianthrones

The electrochemical reduction of several substituted bianthrones is similar to that of the parent compound. 3,3′-Dimethylbianthrone (II), 3,3′-di-n-heptylbianthrone (III). 3,3′-dimethoxybianthrone (IV) and 1,1′-dimethylbianthrone -(V) were studied in dimethylformamide using cyclic voltammetry and transmission mode spectroelectrochemistry. For each compound the low temperature A form is reduced in a two-electron irreversible reaction to a twisted dianion, B^2?. Upon oxidation, B^2? forms first B, then B, whose spectral properties are identical to those of the high-temperature thermochromic form of the bianthrones. Rate constants for the B-A reaction were determined for each compound. The reduction of 2,3,2′,3′-dibenzo-7,7′-dimethylbianthrone (VI) showed somewhat different features which were tentatively interpreted in terms of redox catalysis.     

The effect of sintering on the mineralogy of a synthetic heavy mineral concentrate base prepared by mixing together specpure oxides

Synthetic heavy mineral concentrate standards for calibrating a d.c. arc emission spectrometer were prepared from specpure oxides and compounds. X-ray diffraction and scanning electron microscope studies of the heat-treated synthetic matrix showed that minerals which occurred in natural heavy mineral concentrates were formed. An optimum sintering time of 4 hr was established by monitoring X-ray diffraction peaks of minerals undergoing alteration or being formed in the synthetic base.     

Anomalous low energy Kα lines in Al and Si from high energy oxygen bombardments

Three prominant peaks are observed in Kα X-ray spectra of both Al and Si at energies below the characteristic Kα_1,2 lines. These emission lines were produced by 30 MeV oxygen bombardment and recorded with a crystal spectrometer. The exact origin of these lines is not understood.