High-field magnetoresistance and magnetothermal e.m.f. in many-valley semiconductors with ellipsoidal energy surface

Thermomagnetic coefficients appropriate to a many-valley model of a semiconductor of the n -Germanium type are evaluated in the framework of the density matrix formalism developed earlier. These coefficients are determined for arbitrary values of the magnetic field, within the effective mass approximation. The phonon-drag contribution is not included in this work. An application is made to the four-ellipsoidal model of n-Ge under the conditions where elastic-acoustic phonon scattering is the predominant mechanism of scattering and the high-temperature limit of the phonon distribution is valid. The thermoelectric power (magneto-Seebeck effect) is found to increase with increasing values of the magnetic field except for a small region of low magnetic field values where it decreases in the longitudinal configuration only.     

Design of feedback controllers by two-stage methods

When the eigenvalues of linear, time-invariant discrete systems are widely separated in absolute value, it is shown that the design of state or output feedback controllers can be best approached by two-stage methods. In these methods, the feedback gain matrices are computed by separately placing slow and fast eigenvalues at desired locations. Applications to the problem of independently controlling the speed and torque of petrol engine/dynamometer test rig have demonstrated the potential of the two-stage feedback design methods.     

Paper electrophoresis of growth hormone

Summary A simple method is described for the identification of bovine growth hormone crude fractions using paper electrophoresis. The mobilities of the fractions are tabulated and shown on the extinction curves. The separation of the bands was carried out at room temperature using glycine buffer at pH 10 and Elphor Horizontal apparatus.

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Zusammenfassung Die Rohfraktionen von Rinder-Wachstumshormon wurden papierelektrophoretisch untersucht (Elphor Horizontalgerät; Glycinpuffer pH 10; Zimmertemperatur). Die Versuchsergebnisse für die einzelnen Fraktionen werden tabellarisch und durch eine Abbildung dargestellt.

     

Passivation of Organic-Inorganic Hybrid Sol–Gel

A passivation method for improving long-term stability of organic-inorganic sol–gel material is reported. The effect is observed in experiments with two different passivation materials: Teflon AF and SiO₂. A regime of material curing prior to the passivation is found to strongly affect the optical loss. The degradation of waveguide loss with time due to moisture adsorption from the atmosphere is drastically suppressed by coating the material with a thin silica film. The results indicate a long-term optical loss below 0.3 dB/cm in coated waveguides, significantly smaller than that in uncoated waveguides. The mechanism of the loss reduction is described and experimentally confirmed.     

Channelled spectrum with the double-layer interferometer

The work reported here concerns concentric rings whose centre serves as a fiduciary point and a compensation method is applicable. The applications to dispersion, refraction, length or phase shift measurements are pointed out.     

Solvent free synthesis of 1,3-diaryl-2-propenones catalyzed by commercial acid-clays under ultrasound irradiation

This paper presents a novel solvent free method of synthesis of trans-chalcones. The method was based on ultrasound irradiation of the reagents (aryl methyl ketones and aryl aldehydes) in presence of commercial acid-montmorillonites as catalysts. The trans-chalcones were synthesized in high yields (85–95%) and excellent selectivity in a short reaction time.     

△-Resonances in Ground State Properties of ^40 20Ca Spherical Cold Finite Nucleus at Equilibrium and under Compression

The ground state properties of the spherical nucleus ^40Ca have been investigated by using constrained spherical Hartree Fock （CSHF） approximation at equilibrium and under high radial compression in a six major shells. The effective baryon-baryon interaction that includes the △（1236） resonance freedom degrees to calculate nuclear properties is used. The nucleon-nucleon （N-N） interaction is based on Reid soft core （RSC） potential. The results of calculations show that much of increase in the nuclear energy generated under compression is used to create the massive △ particles. The number of △ ＇s can be increased to about 2.1% of constituents of nucleus when nuclear density reaches about 1.34 times of normal density. The single particle energy levels are calculated and their behavior under compression is also examined. △ good agreement has been found between current calculations and phenomenological shell model for low lying single-particle spectra. The gap between shells is very clear and L-S coupling become stronger as increasing the static load on the nucleus. The results show a considerable reduction in compressibility when freedom degrees of △＇s are taken into account. It has been found that the total nuclear radial density becomes denser in the interior and less dense in the exterior region of nucleus. The surface of nucleus becomes more and more responsive to compression than outer region.