A new time interval analysis system for the on-line monitoring of artificial radionuclides in airborne dust using a phosfitch type alpha/beta detector

A portable system for high-speed time interval analysis (TIA) method was constructed. The system installed with an original time counting board could record pulse incident time of 1 MHz precisely. During the measurement, calculation of time intervals for all the pulses and on-line display of the results were performed simultaneously. Using this system, the correlated decay events of ²¹⁴Bi to ²¹⁰Po in the airborne dust collected on filter paper were counted, together with a dual-phosphor type alpha/beta detector. A rapidly detective technique of artificial radioactivity under the variations of naturally occurring radioactivities is discussed.     

Heteroatom-guided torquoselective olefination of alpha-oxy and alpha-amino ketones via ynolates

Ynolates were found to react with alpha-alkoxy-, alpha-siloxy-, and alpha-aryloxyketones at room temperature to afford tetrasubstituted olefins with high Z selectivity. Since the geometrical selectivity was determined in the ring opening of the beta-lactone enolate intermediates, the torquoselectivity was controlled by the ethereal oxygen atoms. From experimental and theoretical studies, the high Z selectivity is induced by orbital and steric interactions rather than by chelation. In a similar manner, alpha-dialkylamino ketones provided olefins with excellent Z selectivity. These products can be easily converted into multisubstituted butenolides and gamma-butyrolactams in good yield.     

Addition of alkyl radicals, generated from carboxylic acids via photochemical decarboxylation, to glyoxylic oxime ether: a mild and efficient route to α-substituted α-aminoesters

Radical addition to a glyoxylic oxime ether was accomplished under mild conditions using an alkyl radical generated from a free carboxylic acid via photochemical decarboxylation. The photoreaction provided an efficient route to α-substituted α-aminoesters from carboxylic acids and oxime ether.     

Thermal stresses around two parallel cracks in two bonded dissimilar elastic half-planes

Summary Thermal stresses around two parallel cracks in two bonded dissimilar elastic half-planes are determined. One of the cracks lies in the upper half-plane, while the other is in the lower half-plane. Uniform heat flow is assumed to be at right angles to the interface. Application of the Fourier transform technique reduces the problem to that of solving dual integral equations. To solve the equations, the difference of the crack surface temperature and those of the crack surface displacements are expanded in a series of functions which are automatically zero outside the cracks. The unknown coefficients in the series are solved by the Schmidt method. The stress intensity factors are calculated numerially for composite materials featuring a ceramic upper half-plane and a steel lower half-plane.

---

Wärmespannungen um zwei parallele Risse in zwei verbundenen, verschiedenen, elastischen Halbunendlichplatten

Übersicht Es werden die Wärmespannungen um zwei parallele Risse in zwei verbundenen, verschiedenen, elastischen Halbunendlichplatten bestimmt. Einer der beiden Risse liegt in der oberen Halbunendlichplatte, der andere in der unteren. Es wird angenommen, daß ein gleichmäßiger Wärmefluß senkrecht zur Grenzfläche erfolgt. Die Anwendung der Fourier-Transformation reduziert das Problem auf die Lösung dualer Integralgleichungen. Zur Lösung der Gleichungen werden die Temperatur-sowie die Verschiebungsdifferenzen an der Rißoberfläche in eine Reihe von Funktionen entwickelt, die außerhalb der Risse automatisch zu Null werden. Die unbekannten Koeffizienten dieser Reihe werden dann über das Schmidt-Verfahren bestimmt. Anschließend werden für Verbundmaterialien, bei denen die obere Halbunendlichplatte aus Keramik und die untere aus Stahl besteht, die Spannungsintensitätsfaktoren numerisch berechnet.

     

Competing ferromagnetism and superconductivity on FeAs layers in EuFe2(As0.73P0.27)2

We have measured the spin-polarized electron momentum density distributions of EuFe2(As0.73P0.27)2 by magnetic Compton scattering (MCS) measurements. For the first time, we show direct evidence of competing ferromagnetism and superconductivity (SC) on FeAs layers in this iron pnictide system. The MCS orbitalwise decomposition of the density distributions reveals that between 16 and 19 K, the spin-polarized Fe-3d character is enhanced (as the ferromagnetic character supersedes superconducting character), where the resistivity shows a maximum, reentrant SC-like peak, at 18 K. The spin polarization of the Fe-3d orbital, enhanced by ferromagnetic Eu ions, suppresses the SC around 18 K, while at other temperatures the system indeed exhibits SC where the Fe-3d spin polarization is suppressed or collapses.     

Tantalum(V) or niobium(V) catalyzed oxidation of sulfides with 30% hydrogen peroxide

Tantalum(V) and niobium(V) are effective catalysts for the oxidation of sulfides with 30% hydrogen peroxide. The reaction of sulfides with 30% hydrogen peroxide catalyzed by tantalum(V) chloride or niobium(V) chloride in acetonitrile, i-propanol or t-butanol selectively provided the corresponding sulfoxides in high yields. The corresponding sulfones are efficiently obtained from the reaction of sulfides with 30% hydrogen peroxide in methanol catalyzed by tantalum(V) or niobium(V).     

Spin-dependent electron momentum densities in Co2FeGa studied by Compton scattering

The spin density of Heusler alloy Co₂FeGa, has been studied using the Compton scattering technique with 274 keV circularly polarized synchrotron radiation in the high energy inelastic scattering beamline (BL08W), at SPring-8, Japan. The magnetic Compton profiles along the two principal directions [1 1 0] and [1 1 1] were measured. The spin profiles shows a good agreement with our FLAPW-GGA results, where the theoretical results were based on the ferromagnetic ground state. The 3d spin moment at the Co and the Fe site was found to be in excellent agreement with the earlier reported neutron diffraction measurements.