Reflection of a pulse by multiple-dielectric layers

The reflection of a pulse by multiple-dielectric layers is treated theoretically. The reflected wave is obtained by expanding the reflection coefficient of an elementary plane wave in a series, including the special case for which total reflection occurs. The pulsed waves reflected by two-dielectric slabs are considered in detail both analytically and numerically. The effect of a carrier frequency of a pulse-modulated carrier wave on the reflected wave form is also discussed.     

The contact charge density of conduction electrons of Fe in Co metal as derived from internal conversion

From an internal-conversion measurement of the 14.4 keV transition ⁵⁷Fe, the contact 1 charge density of conduction electrons for Fe in Co metal was obtained to be ?_4s(0) = 4.6 ±0.4 a₀⁻³, which is close to theoretical values but is smaller than that for Fe in Fe metal obtained recently.     

Determination of testosterone propionate in human plasma by gas chromatography-mass spectrometry

A specific, sensitive and accurate quantitative analysis of testosterone propionate in human plasma was developed using gas chromatography-mass spectrometry-selected-ion monitoring. For the calculation of testosterone propionate in plasma, peak height ratios were measured by selected-ion monitoring performed on the molecular ions of the trifluoroacetyl derivative of testosterone propionate (m/z 440) and testosterone propionate-19,19,19-d3 (m/z 443). The sensitivity of the method was judged from the lower limit of the detection of the mass spectrometer which was at 20 pg. The inter-assay coefficients of variation and relative error at a concentration of 1.31 ng/ml of plasma were 5.47% and -2.3%, respectively. The method described was applied to the determination of plasma concentrations of testosterone propionate-19,19,19-d3 following an intramuscular dose of testosterone propionate-19,19,19-d3 in a healthy male volunteer.     

Contact density and number of 5s electrons inβ-Sn

Lifetimes and feeding times of high spin states in ¹⁵⁶ Er have been measured employing the recoil distance method in the reaction ¹²³ Sb(³⁷ Cl,4n) at bombarding energies of 158 and 166 MeV. The yrast states up to spin 20 ? were found to be collective. These levels are fed, however, from long-lived high spin states, causing time delays up to ～ 100 ps, the existence of which is interpreted as a signature for an oblate shape at high spin.     

Raman scattering studies of the Ba2MnWO6 and Sr2MnWO6 double perovskites

Polycrystalline Ba2MnWO6 (BMW) and Sr2MnWO6 (SMW) samples were studied between 80 and 1200 K by Raman scattering spectroscopy. In the case of BMW (space group Fmm), four Raman active vibrational modes, predicted by factor group analysis, were identified. Raman scattering studies with different wavelengths revealed a resonant bands between 300 and 800 cm-1. The origin of these bands was related to the Franck-Condon process. Line broadening versus temperature and phonon frequency were studied, and a qualitative explanation was proposed. SMW samples had considerably more complex Raman spectra. It was found that SMW transformed from tetragonal (room-temperature space group P42/n) to the cubic phase between 670 and 690 K; the phase transition temperature was dependent on sample preparation conditions, and it was considerably lower than in the case of large grain size powders. The role of grain size in phase transition is discussed. Mn ions were found to have a crucial role in the lattice dynamics of both materials.     

Intramolecular bromo-amination of 1,4-cyclohexadiene aminal: one-pot discrimination of two olefins and concise asymmetric synthesis of (-)-gamma-lycorane

The reaction of cyclohexa-2,5-dienyl-1-methylaldehyde and optically pure 1,2-diaryl-1,2-diamine followed by intramolecular bromo-amination produced a one-pot discrimination of two olefins in the cyclohexane system, which was used for the asymmetric synthesis of (-)-gamma-lycorane.     

Chirality control in oligothiophene through chiral wrapping

[structure: see text] Mixing oligothiophenes and polysaccharides, such as amylose and schizophyllan, affords novel inclusion complexes, in which oligothiophene guests adopt twisted conformation in the chiral channel created by left- or right-handed helical wrapping with the polysaccharide host polymers, leading to optical activity.     

First enantioselective synthesis of salinipostin A,a marine cyclic enol-phosphotriester isolated from Salinispora sp

Salinipostins are cyclic enol-phosphotriesters isolated from a marine-derived Salinispora sp. as antimalarial compounds. Herein, the first enantioselective synthesis of salinipostin A was achieved. Organocatalyst-mediated asymmetric cyclopropanation and regioselective cyclopropane ring opening were the key steps.