Consistent aromaticity evaluations of methylenecyclopropene analogues

Quantitative evaluations of the aromaticity (antiaromaticity) of neutral exocyclic substituted cyclopropenes (HC)(2)C=X (X = BH to InH (group 13), CH(2) to SnH(2) (group 14), NH to SbH (group 15), O to Te (group 16)) by their computed extra cyclic resonance energies (ECRE, via the block-localized wave function method) and by their aromatic stabilization energies (ASEs, via energy decomposition analyses) correlate satisfactorily (R(2) = 0.974). Electronegative X-based substituents increase the aromaticity of the cyclopropene rings, whereas electropositive substituents have the opposite effect. For example, (HC)(2)C=O is the most aromatic (ECRE = 10.3 kcal/mol), and (HC)(2)C=InH is the most antiaromatic (ECRE = -15.0 kcal/mol). The most refined dissected nucleus-independent chemical shift magnetic aromaticity index, NICS(0)(πzz), also agrees with both energetic indexes (R(2) = 0.968, for ECRE; R(2) = 0.974, for ASE), as do anisotropy of the induced current density plots.     

Growth of suppression in humans based on distortion-product otoacoustic emission measurements

Distortion-product otoacoustic emissions (DPOAEs) were used to describe suppression growth in normal-hearing humans. Data were collected at eight f(2) frequencies ranging from 0.5 to 8 kHz for L(2) levels ranging from 10 to 60 dB sensation level. For each f(2) and L(2) combination, suppression was measured for nine or eleven suppressor frequencies (f(3)) whose levels varied from -20 to 85 dB sound pressure level (SPL). Suppression grew nearly linearly when f(3) ≈ f(2), grew more rapidly for f(3)?< f(2), and grew more slowly for f(3)?> f(2). These results are consistent with physiological and mechanical data from lower animals, as well as previous DPOAE data from humans, although no previous DPOAE study has described suppression growth for as wide a range of frequencies and levels. These trends were evident for all f(2) and L(2) combinations; however, some exceptions were noted. Specifically, suppression growth rate was less steep as a function of f(3) for f(2) frequencies ≤ 1 kHz. Thus, despite the qualitative similarities across frequency, there were quantitative differences related to f(2), suggesting that there may be subtle differences in suppression for frequencies above 1 kHz compared to frequencies below 1 kHz.     

Prior exposure to an attenuated <Emphasis Type="Italic">Listeria</Emphasis> vaccine does not reduce immunogenicity: pre-clinical assessment of the efficacy of a <Emphasis Type="Italic">Listeria</Emphasis>vaccine in the induction of immune responses against HIV

Background  

We have evaluated an attenuated Listeria monocytogenes (Lm) candidate vaccine vector in nonhuman primates using a delivery regimen relying solely on oral vaccination. We sought to determine the impact of prior Lm vector exposure on the development of new immune responses against HIV antigens.     

CaL-B a highly selective biocatalyst for the kinetic resolution of furylbenzthiazole-2-yl-ethanols and acetates

A highly stereoselective enzymatic kinetic resolution of novel various substituted racemic furylbenzthiazole-2-yl-ethanols and their acetates has been developed. Both processes, the enzymatic acylation of the racemic alcohols and the enzymatic methanolysis of racemic acetates yielded highly enantiomerically enriched (ee >98%) resolution product, when CaL-B was used as a biocatalyst in acetonitrile. The absolute configuration of the obtained (R)-(+)-1-(5-(4-chlorobenzo[d]thiazol-2-yl)furan-2-yl)ethanol was determined by a detailed ¹H NMR study of rac- and (+)-1-(5-(4-chlorobenzo[d]thiazol-2-yl)furan-2-yl)ethanol Mosher derivatives.     

Ultrasonic guided wave inspection with array sensors

Ultrasonic guided wave becomes one of promising tool for monitoring various types of structures such as large steel plates, vessels, and pipes in oil, chemical or nuclear industry, because guided waves have ability to travel wide range of the target structure in a single position. However, analysis of guided wave signals acquired from structure is difficult on account of low S/N ratio and its dispersive nature. To improve S/N ratio and overcome dispersion effect, focusing techniques for guided waves are needed. Thus, in this study, focusing techniques for guided waves were developed in order to improve long range inspection ability, and performance of the developed techniques was verified by experiments.     

A modular design of ruthenium(II) catalysts with chiral C2-symmetric phosphinite ligands for effective asymmetric transfer hydrogenation of aromatic ketones

Hydrogen-transfer reduction processes are attracting increasing interest from synthetic chemists in view of their operational simplicity. The new chiral C₂-symmetric ligands N,N′-bis-[(1S)-1-sec-butyl-2-O-(diphenylphosphinite)ethyl]ethanediamide, 1 and N,N′-bis-[(1S)-1-phenyl-2-O-(diphenylphosphinite)ethyl]ethanediamide, 2 and the corresponding ruthenium complexes 3 and 4 have been prepared and their structures have been elucidated by a combination of multi-nuclear NMR spectroscopy, IR spectroscopy, and elemental analysis. ¹H–³¹P NMR, DEPT, ¹H–¹³C HETCOR, or ¹H–¹H COSY correlation experiments were used to confirm the spectral assignments. The catalytic activity of complexes 3 and 4 in transfer hydrogenation of acetophenone derivatives by iso-PrOH has also been studied. Under optimized conditions, these chiral ruthenium complexes serve as catalyst precursors for the asymmetric transfer hydrogenation of acetophenone derivatives in iso-PrOH and act as excellent catalysts, giving the corresponding chiral alcohols in 99% yield and up to 75% ee. This transfer hydrogenation is characterized by low reversibility under these conditions.     

The AR-property for Roberts' example of a compact convex set with no extreme points Part 2: Application to the example

In this second part of our paper, we apply the result of Part 1 to show that the compact convex set with no extreme points, constructed by Roberts (1977), is an AR.

     

Ⅱ -Ⅳ族化合物半导体超微粒子光谱性质的研究Ⅱ : 硒化物、碲化物

本文报道了锌、镉、汞、铅硒化物、碲化物半导体超微粒子的制备以及它们的光谱性质 ,比较了它们的粗、细粒子的吸收光谱和荧光光谱的差异 ,以及与硫化物超微粒子的相似性 ,同时讨论了上述物质的超微粒子在老化过程中的行为及其原因.