IR spectroscopic study of the conformational lability of 4′-ethyl-4-cyanobiphenyl

The conformational lability of 4wk4837270u636116/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-ethyl-4-cyanobiphenyl molecules in solid crystal (SC) and isotropic liquid (IL) states was investigated by IR spectroscopic techniques (experiment and theory). IR absorption spectra were measured at 28°C–95°C in the frequency range 400 cm^–1–4000 cm^–1. Spectrum simulation was performed using the fragment method with allowance for the conformational fluctuations of molecules. The experimental and calculated spectra were compared and analyzed, and it was shown that in the IL, the samples are mixtures of conformers. The temperature changes in the spectra in the stated range are caused by the conformational lability of molecules.Original Russian Text Copyright © 2004 by L. M. Babkov, I. I. Gnatyuk, G. A. Puchkovskaya, and S. V. TrukhachevTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 398–405, May–June, 2004.     

Elimination of surface scratch/texture on the surface of single crystal Si substrate in chemo-mechanical grinding (CMG) process

Si wafers are widely used as a substrate material for fabricating ICs. The quality of ICs depends on the quality of Si wafers. The chemo-mechanical grinding (CMG) with soft abrasive grinding wheels (SAGW) has been recently found to be a great potential process for machining Si wafers to generate superior surface quality at low cost. However, there have been very few studies on observing variation of topography of scratch/texture and understanding basic eliminating process of scratch/texture on the ground Si wafer. Furthermore, few reports on the variation of surface roughness and material removal rate (MRR) during CMG process and relationship between MRR and surface roughness during CMG process are presented. In this paper, a series of CMG experiments have been conducted to study the elimination process of artificial scratches created on etched Si surfaces and residual textures induced by SD1500 diamond wheel in CMG process, and to understand the topography variations of Si surfaces and some basic grinding characteristics during CMG process.     

Theoretical studies of (d-p)ρ bonding,electronic spectra,and reactivities in homo- and heterometallic clusters: [Mo3- n W n X4(H2O)9]4+ ( X = O,S, Se,Te;n= 0-3)

Ab initio calculations with relativistic effective potentials have been carried out on 12 trinuclear molybdenum/tungsten cluster aqua ions [M₃X₄(H₂O)₉]^4– (M₃= Mo₃, W₃ for X = O, S, Se, Te; M₃=Mo₂W, MoW₂ for X = O, S). The electronic structures and bonding pictures of l-12 are discussed in terms of the delocalized and localized molecular orbitals as well as the Mulliken populations, natural populations, and Mayer bond orders. It is shown that the (d-p)wk13616327770436/xxlarge961.gif" alt="rgr" align="MIDDLE" BORDER="0"> bonding in the puckered six-membered ring of the [M₃(µ-X)₃] core arises from a closed continuous ring of three mutually adjacent localized (d-p-d)wk13616327770436/xxlarge961.gif" alt="rgr" align="MIDDLE" BORDER="0"> bonds with strong interactions. It is these three-centered two-electron (d-p-d)wk13616327770436/xxlarge961.gif" alt="rgr" align="MIDDLE" BORDER="0"> bonds that account for the unusual physicochemical properties and reactivities of these cluster compounds. The wavelengths and the assignment of electronic spectra have been given, and the relation between the wavelength shili and the (d-p)wk13616327770436/xxlarge961.gif" alt="rgr" align="MIDDLE" BORDER="0"> bonding is discussed, The reactivities of the ligand substitution reactions and two kinds of addition reactions as weil as some kinetic and redox properties of these compounds are briefly discussed by taking advantage of this Iocalization (d-p-d)wk13616327770436/xxlarge961.gif" alt="rgr" align="MIDDLE" BORDER="0"> a bonding picture.     

On nonregular ideals and <Emphasis Type="Italic">z</Emphasis>°-ideals in <Emphasis Type="Italic">C</Emphasis>(<Emphasis Type="Italic">X</Emphasis>)

The spaces X in which every prime z°-ideal of C(X) is either minimal or maximal are characterized. By this characterization, it turns out that for a large class of topological spaces X, such as metric spaces, basically disconnected spaces and one-point compactifications of discrete spaces, every prime z°-ideal in C(X) is either minimal or maximal. We will also answer the following questions: When is every nonregular prime ideal in C(X) a z°-ideal? When is every nonregular (prime) z-ideal in C(X) a z°-ideal? For instance, we show that every nonregular prime ideal of C(X) is a z°-ideal if and only if X is a ?-space (a space in which the boundary of any zeroset is contained in a zeroset with empty interior).     

Improvement of fat digestion in rats by dimethyl-β-cyclodextrin

Heptakis-(2,6-di-O-methyl)-wk07k3p87820/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin (DIMEB), a compound having a great water-solubility enhancing effect on lipids via inclusion complex formation was investigated as a potential bile-substituting agentin vivo in rats. The normal fat digestion was inhibited by ligating the bile duct. 3-H-Stearic acid or edible oil were administered orally to rats and the effect of simultaneously administered DIMEB on the lipid absorption was studied by measuring the blood radioactivity level or plasma triglyceride and free fatty acid concentrations. The lipid absorption was significantly improved by DIMEB. Accordingly, it seems to be a new fat digestion and absorption enhancing drug, i.e. a possible bile-substituting agent.Presented at the Fourth International Symposium on Inclusion Phenomena and the Third International Symposium on Cyclodextrins, Lancaster, U.K., 20–25 July 1986.     

New method for the synthesis of α-chlorocinnamonitriles

A novel method for the preparation of nitriles of wk08v2/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-chlorocinnamic acid from aldehydes and ketones was proposed. Transformation of carbonyl compounds into hydrazones followed by treatment of the reaction mixture with CCl₃CN in the presence of copper chloride(i) yields wk08v2/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-chlorocinnamonitriles.