Crystallographic analysis of 9-(3-methylbut2-enyloxyfurano)[3,2-g] benzopyran-2-one

This structure of 9-(3-methylbut-2-enyloxyfurano)[3,2-g] benzopyran-2-one has been determined by X-ray diffraction methods. The compound crystallizes in the triclinic (space group P \(bar 1\)) with the unit cell parameters a = 11.1150(10), b = 11.8240(10), c = 11.9290(10) Å, α = 64.90(1)^°, β = 83.53(1)^°, γ = 89.25(1)^° and Z = 4. The structure has been solved by direct methods and refined to reliability index of 0.043. The unit cell contains two crystallographically independent molecules in the asymmetric unit, which exhibit different side-chain conformations. The crystal structure is stabilized by the intra molecular and intermolecular C–H?sO interactions.     

Nonnegative matrices having nonnegative Drazin pseudoinverses

Necessary and sufficient conditions for nonnegative matrices having nonnegative Drazin pseudoinverses are obtained. A decomposition theorem which characterizes the class of all nonnegative matrices with nonnegative Drazin pseudoinverses is proved, thus answering a question raised by several people. It is also shown that if a row (or column) stochastic matrix has a nonnegative Drazin pseudoinverse A(^d), then A(^d) is some power of A. These results extend known results for nonnegative group-monotone matrices.     

Evidence supporting a single electron transfer pathway in the reduction of aromatic ketones by metal alkoxides. Lithium isopropoxide,an excellent reducing agent for aromatic ketones.

Reactions of various metal alkoxides with aromatic ketones have been shown to produce radical intermediate. Lithium isopropoxide has been found to be an excellent reducing agent for aromatic ketones and reduces benzophenone at a faster rate than does aluminum isopropoxide.     

Evidence for single electron transfer in the reduction of alcoholswith lithium aluminum hydride

EPR evidence supporting a single electron transfer mechanism in the reduction of secondary and tertiary alcohols to hydrocarbons with LiAlH₄ is presented.     

Nonnegative mth roots of nonnegative 0-symmetric idempotent matrices

Nonnegative mth roots of nonnegative 0-symmetric idempotent matrices have been characterized. As an application, a characterization of nonnegative matrices A whose Moore-Penrose generalized inverse A² is some power of A is obtained, thus yielding some well-known theorems.     

Experimental study of the variation of the plasma temperature with the laser flux

Experiments performed with a 50 MW — 60 nsec ruby laser to estimate the temperature of the plasma produced on the planar targets of carbon as well as polyethylene are reported. Temperatures were estimated by two foil ratio technique. The temperatures of carbon and polyethylene plasma show aφ ^2/9 dependance on flux in the flux regime of 10¹⁰ W/cm² to 5 × 10¹¹ W/cm². The comparatively slower dependance is explained on the basis of purely collisional absorption, the effect being enhanced due to relatively long duration of the laser pulses. Scaling laws of plasma temperature against laser flux obtained by different workers in different flux regimes have been analysed on the basis of collisional and non-collisional absorption.     

Electroproduction of η mesons in the region of the resonances S11(1535)

We report on an experiment on electroproduction in the resonance region in the mass range 1505 ? W ? 1715 MeV. Data have been taken at q² = 0. 22, 0.6 and 1 GeV². The angular distributions obtained support that η production proceeds mainly through S-wave excitation due to the resonance S₁₁(1535).The total cross section of the formation of this resonance decreases much more slowly with increasing momentum transfer than the total ep cross section.