Thermal placement of elements of integrated circuits on crystal surface

The criterion and the corresponding approach for the thermal placement of integrated circuits (IC) elements on the crystal surface are proposed. The criterion of placement is identical to the traditional criteria of minimizing the total length of connections between elements, which at the placement stage enables to apply an additive multiparametric criterion of joint consideration of electrical and thermal modes for operating of the IC elements.     

Synthesis of alpha-amino acids via asymmetric phase transfer-catalyzed alkylation of achiral nickel(II) complexes of glycine-derived Schiff bases

Achiral, diamagnetic Ni(II) complexes 1 and 3 have been synthesized from Ni(II) salts and the Schiff bases, generated from glycine and PBP (7) and PBA (11), respectively, in MeONa/MeOH solutions. The requisite carbonyl-derivatizing agents pyridine-2-carboxylic acid(2-benzoyl-phenyl)-amide 7 (PBP) and pyridine-2-carboxylic acid(2-formyl-phenyl)-amide 11 (PBA) were readily prepared from picolinic acid and o-aminobenzophenone or picolinic acid and methyl o-anthranilate, respectively. The structure of 1 was established by X-ray crystallography. Complexes 1 and 3 were found to undergo C-alkylation with alkyl halides under PTC conditions in the presence of beta-naphthol or benzyltriethylammonium bromide as catalysts to give mono- and bis-alkylated products, respectively. Decomposition of the complexes with aqueous HCl under mild conditions gave the required amino acids, and PBP and PBA were recovered. Alkylation of 1 with highly reactive alkyl halides, carried out under the PTC conditions in the presence of 10% mol of (S)- or (R)-2-hydroxy-2'-amino-1,1'-binaphthyl 31a (NOBIN) and/or its N-acyl derivatives and by (S)- or (R)-2-hydroxy-8'-amino-1,1'-binaphthyl 32a (iso-NOBIN) and its N-acyl derivatives, respectively, gave rise to alpha-amino acids with high enantioselectivities (90-98.5% ee) in good-to-excellent chemical yields at room temperature within several minutes. An unusually large positive nonlinear effect was observed in these reactions. The Michael addition of acrylic derivatives 37 to 1 was conducted under similar conditions with up to 96% ee. The (1)H NMR and IR spectra of a mixture of the sodium salt of NOBIN and 1 indicated formation of a complex between the two components. Implications of the association and self-association of NOBIN for the observed sense of asymmetric induction and nonlinear effects are discussed.     

Manganese catalysed asymmetric cis-dihydroxylation with H2O2

High turnover enantioselective alkene cis-dihydroxylation is achieved with H(2)O(2) catalysed by manganese based complexes containing chiral carboxylato ligands.     

Features of hopping conductivity in weakly doped and weakly compensated semiconductor quantum wells

Main features of hopping transport in quantum wells in the conditions of low doping and low compensation are considered. Based on the features of the classical law of interaction between the impurities and on the percolation problem in quantized wells, it is shown that the specific resistance and activation energy of donor centers of the well are determined by the doping parameters and sharply depend on the width of the well.     

Copper(I) catalyzed asymmetric 1,2-addition of Grignard reagents to α-methyl substituted α,β-unsaturated ketones

The first catalytic enantioselective 1,2-addition of Grignard reagents to ketones is presented. This additive-free copper(I) catalyzed 1,2-addition provides chiral allylic tertiary alcohols with an er of up to 98:2 and excellent yields due to the complete shift of overwhelming 1,4-selectivity of copper(I)-catalysts towards 1,2-selectivity in the addition reaction to enones.     

Magnetocaloric effect of compounds in Gd<Subscript>5−<Emphasis Type="Italic">x</Emphasis></Subscript>Dy<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Si<Subscript>2</Subscript>Ge<Subscript>2</Subscript> system

Magnetization of magnetically ordered Gd_5−x Dy _x Si₂Ge₂ compounds with a partial substitution of Gd atoms by isovalent Dy atoms has been investigated. From temperature and field dependences of Gd_5−x Dy _x Si₂Ge₂ alloys with x = 0−2.0 changes of the magnetic part of entropy (ΔS _M ) of alloys are determined. It is established that ΔS _M achieves its maximum values at different temperatures, which linearly depend on the Dy concentration, and their values are comparable with ΔS _M ^max in Gd₅Si₂Ge₂. The obtained data allow us to conclude that the above-mentioned compounds have high magnetocaloric effect and are promising materials for using as a combined working body of magnetic refrigerators operating in the 200–270 K range of temperatures.     

Semiconductor nanocylindrical layer in a strong electric field: Spectrum of carriers and intraband transitions

The single-electron states in a quantized cylindrical layer in the presence of a strong homogeneous electric field have been considered in the isotropic effective mass approximation. The energy spectrum and the envelope wave functions of charge carriers in the layer have been obtained in the explicit form. It has been shown that a strong external electric field leads to an additional localization of carriers in their angular motion. The corresponding selection rules have been derived, and the absorption band of intraband-intersubband optical transitions in the layer has been calculated.