Lewis acid promoted annulation of p-quinoneimines by allylsilanes: a facile entry into benzofused heterocycles

[reaction: see text] Lewis acid promoted addition of allyltriisopropylsilane to p-quinoneimines afforded different benzofused heterocycles in moderate to good yields depending on the conditions employed.     

Hydrogenated silicon fullerenes: effects of H on the stability of metal-encapsulated silicon clusters

Ab initio calculations of H interaction on Si12M, Si18M2 (M=Cr, Mo, and W), and Zr@Si(16) fullerene (f) show relatively weak binding of H in agreement with experimental results of H free Si12M and Si18M2 clusters. Adsorption of H enhances sp(3) bonding between the Si atoms, weakens the M-Si cage interactions, and leads to distortions in the cages. Si12CrH12 has 4 mu(B) magnetic moment in contrast to zero for Si12Cr. Removal of the M atom leads to stable empty cages of Si12H12, f-Si16H16, and f-Si20H20 with large highest occupied-lowest unoccupied molecular orbital gaps of 2.5-3.0 eV, making them attractive for optoelectronic applications.     

Bioremediation of soil contaminated with organic compounds with special reference to acrylonitrile

Enrichment of acrylonitrile (AN) degrading bacterial culture from contaminated soil resulted in the isolation of two cultures which were identified as gram negative small rods (C1) and gram positive cocci (C2). One of the cultures (C1) was identified as Citrobacter fruendii on the basis of biochemical and physiological tests. Both the cultures (C1 and C2) were able to utilize acrylonitrile up to a concentration of 2000 mg/l as the sole source of carbon and nitrogen. The studies also confirmed that the acrylonitrile contaminated soil when ploughed with well mixed AN degrading culture, diammonium phosphate and farmyard manure, could be completely remediated within two months from the date of soil amendment.     

A sharp estimate on the degree of approximation to functions of bounded variation by certain operators

Recently Guo^[2] introduced integrated Meyer-König and Zeller operators and studied the rate of convergence for function of bounded variation. In this note we give a sharp estimate for these operators.     

NONMARKET RESOURCE VALUATION: A BILEVEL OPTIMIZATION APPROACH

The social value of a common property/open access resource is in general different from the value attributed by individual users. Therefore, public intervention in the form of prices, quotas and marketable licenses has often been necessary to prevent overexploitation of such resources. This paper addresses the pricing issue. The existing mathematical programming studies in the resource economics literature suggest using the shadow price information obtained from an aggregate model where the sum of net returns to individual users and the management authority is maximized. When the policy maker's objective takes a different form, however, the shadow price strategy may result in a socially suboptimum or infeasible resource utilization. A bilevel optimization approach is proposed in this paper where the price of the resource is introduced as a policy variable and the optimizing behavior of individual users is considered as an explicit constraint in a global optimization problem. An empirical application of the proposed approach to the steady state management of a large scale irrigation system is presented.     

Grouping multi-item inventory using common cycle periods

Multi-item inventory control may be simplified by grouping items into subgroups with a common order cycle for all the items in each group. The methods provided in the literature for determination of the order cycle values are either suboptimal or computationally inefficient. This note proposes a procedure which finds the optimal values and is also computationally efficient.     

Electrochemical reduction of α,α′-Dibromo-dibenzylsulfone, -sulfoxide,and -sulfide

The electrochemical reduction of the title compounds in dimethylformamide affords in all cases stilbene as a major product, leading to the conclusion that cyclization to a three-membered ring containing sulfur is a common feature in these reductions. Other products isolated in the reductions help to shed light upon the course of the reactions.     

Intermediacy of bicyclo[2.2.1]hepteneone in the photolysis of bicyclo[2.2.2]octenediones

UV Irradiation of cyclohexane solution of bicyclo[2.2.2]octenediones led to facile extrusion of carbon monoxide to give substituted dihydrobiphenyls along with the dehydrogenated products. The inseparable mixtures on DDQ oxidation afforded the biphenyl derivatives. Isolation of an intermediate arising from the initial monodecarbonylation lends support to a proposed mechanistic rationalization.