Effect of electroplastic processing on the structure of aluminum-lithium alloy 1463

The effect of electroplastic rolling of aluminum-lithium alloy 1463 on its structural evolution has been considered. The differences in the structures formed under rolling with passage of a constant or pulse current through the deformation zone and under current-free processing have been studied.     

Lone pairs vs. covalent bonds: conformational effects in bicyclo[3.3.1]nonane derivatives

Structural Chemistry - Investigations on the relative energy of two least-strain conformers for bicyclo[3.3.1]nonane 1, bicyclo[3.3.1]nonan-9-one 2, and their heteroanalogues:...     

The Nature of Anomalous Particles (Granules) in Rapidly Quenched PREP Powders—II. A Multiscale Study of PREP Powders and PM HIP Compacts of Ni-Based Superalloys and Stainless Steels

Physics of Atomic Nuclei - The formation of anomalous particles (granules) with a significantly different content of microalloying interstitial elements of carbon and boron characterizes the...     

A monopole mass filter with a hyperbolic V-shaped electrode

In this article we compare the classical monopole mass filter of von Zahn and the monopole mass filter with a hyperbolic V-shaped electrode. The experimental results and those of computer simulation for both mass spectrometers are presented. We show that the replacement of a conventional 90 degrees V-shaped electrode by an electrode with a hyperbolic profile substantially improves the peak shape of any given mass, and increases the mass resolution by a factor of 3-4 and the abundance sensitivity by a factor of 100. The potential of high analytical performance combined with electroforming techniques for electrode manufacture indicate future practical uses of such instruments. Copyright 1999 John Wiley & Sons, Ltd.     

Simulation of sputtering from ion-beam-roughened carbon surfaces

Effects of ion-induced surface roughness on sputtering of amorphous carbon under ion bombardment are studied by means of binary-collision computer simulation in a wide range of incidence angles. Most simulations refer to 1–10?keV Ar ion bombardment, and sinusoidal ripple morphology is assumed. It is shown that surface roughness is a key factor to achieve quantitative agreement with experiment. The simulation results are compared with the analytical estimates of the yield from sine-shaped and ridged surfaces based on continuum models of ion sputtering. Some deviations between the results are discussed.     

On a way to new types of the polyfunctional and polytopic systems based on cage metal complexes: Cadmium-promoted nucleophilic substitution with low-active nucleophilic agents

The nucleophilic substitution of the reactive halogen atoms of clathrochelate precursors with soft nucleophilic agents was promoted by cadmium(II) ion using various types of cadmium-containing compounds. Cadmium(II) activates the C–Hal bond both by the coordination of halogen substituents to this ion and the formation of anionic forms of a nucleophilic agent with cadmium amides, that increase the electron density on a reactive site of this agent. The cadmium-promoted substitution reactions of the reactive chlorine ribbed substituents in the di- and hexachlorine-containing clathrochelate precursors afforded the clathrochelate ribbed-functionalized derivatives of soft nucleophiles [alcohols (including fluorinated ones) and aromatic amines (including the nucleophiles with electron-withdrawing substituents)] by efficient one-pot procedures in high yields under mild conditions with generated in situ low-basic cadmium(II) alcoholates and amides. The complexes obtained were characterized using elemental analysis, MALDI-TOF mass spectrometry, IR, UV–Vis, ⁵⁷Fe Mössbauer, and NMR spectroscopies, and X-ray crystallography. The potential of cadmium-promoted reactions for synthesis of different types of organic and coordination compounds is discussed.     

Synthesis and Some Reactions of 6H-Indolo[2,3-b]quinoxalines

Russian Journal of Organic Chemistry - 6H-Indolo[2,3-b]quinoxalines were synthesized by condensation of isatin and 5-nitroisatin with o-phenylenediamine. The alkylation of the title compounds with...     

Analysis of photoluminescence spectra of anthracene traces in photon traps

Photoluminescence spectra of small amounts of anthracene being in the photon trap, a specific type of the resonant cavity, were measured. In photon traps, radiation is input and output by optical waveguides. The use of ultraviolet light-emitting-diode sources of exciting radiation and a minipolychromator allowed photoluminescence spectra measurements in the range of 340–500 nm at an exposure of ～ 10^?3 s.     

NMR Study of the graphite–<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylformamide system after ultrasonication

A suspension formed as a result of ultrasonication of a mixture of graphite with N,N-dimethylformamide has been studied by ¹H NMR spectroscopy. The dependence of the width of the ¹H NMR signal on the N,N-dimethylformamide content of the suspension has been determined.     

Structured water in partially dehydrated yeast cells and at partially hydrophobized fumed silica surface

Nonfreezable water structured due to interaction with endocellular objects in yeast cells (endocellular water) or with partially hydrophobic fumed silica (interfacial water) was studied by means of (1)H NMR spectroscopy with layer-by-layer freezing-out of bulk water and quantum chemical methods applied to water clusters in the gas and liquid (chloroform and cyclohexene) phases and adsorbed on silylated silica. Variation in cell hydration as well as in amount of water adsorbed on modified fumed silica leads to changes in the ratio between contributions of two water states characterized by NMR chemical shifts at delta(H)=1.1-1.7 and 4-5 ppm. Lowering of hydration and temperature results in an enhancement of the first signal, and the opposite result is observed for the second signal. These effects may be explained by structured water distribution in the form of relatively large nanodroplets (delta(H)=4-5 ppm is close to that for bulk water) and small clusters of the 2D structure, in which the fraction of hydrogen atoms out of the hydrogen bonds (delta(H)=1.1-1.7 ppm) is larger than that in nanodroplets.