Fourth-order orbital equations in stationary weak gravitational fields

The equations of motion in fourth approximation for gravitational bodies are used to obtain orbital equations, first integrals, differential equations for the corresponding trajectories, and fourth-order contributions to the orbital motions in stationary weak gravitational fields.     

ECR Plasma in Growth of Cubic GaN by Low Pressure MOCVD

To heteroepitaxally grow the crystalline cubic-GaN (c-GaN) film on the substrates with large lattice mismatch is basically important for fabricating the blue or ultra-violet laser diodes based on cubic group III nitride materials. We have obtained the crystalline c-GaN film and the heteroepitaxial interface between c-Gan and GaAs(001) substrate by the ECR Plasma-Assisted Metal Organic Chemical Vapor Deposition (PA-MOCVD) under low-pressure and low-temperature (600°C) on a homemade ECR-plasma Semiconductor Processing Device (ESPD). In order to decrease the growth temperature, the ECR plasma source was adopted as the activated nitrogen source, therefore the working pressure of MOCVD was decreased down to the region less than 1 Pa. To eliminate the damages from energetic ions of current plasma source, a Multi-cusp cavity-coupling ECR Plasma source (MEP) was selected to use in our experiment. To decrease the strain and dislocations induced from the large lattice mismatch between c-GaN and GaAs substrate, the plasma pretreatment procedure i.e., the initial growth technique was investigated. The experiment arrangements, the characteristics of plasma and the growth procedure, the characteristics of c-GaN film and interface between c-GaN and GaAs(001), and the roles of ECR plasma are described in this contribution.     

On the rational cuspidal subgroup and the rational torsion points of

For two distinct prime numbers , , we compute the rational cuspidal subgroup of and determine the -primary part of the rational torsion subgroup of the old subvariety of for most primes . Some results of Berkovic on the nontriviality of the Mordell-Weil group of some Eisenstein factors of are also refined.

     

Oxidation ofn-butane and propene on exhydrotalcite Mg, Al, Fe mixed oxides

Oxidative dehydrogenation ofn-butane and propene has been studied on six Mg−Al−Fe oxide catalysts prepared by thermal decomposition of layered double hydroxides with a hydrotalcite-like structure, possessing Mg²⁺ and Al³⁺ ions in the brucite-like layers, and hexacyanoferrate in the interlayers. In all cases, CO₂ and H₂O are formed, together with minor amounts of ethylene and methane. On the solids prepared from hexacyanoferrate(II), formation of benzene is also observed.     

Cyanosugars III : The reaction of trimethylsilyl cyanide with keto,epoxy and acetal derivatives of carbohydrates

Reaction of methyl 2-acetamido-4,6-$\text{O}$-benzylidene-2-deoxy-α-$\text{D}$-$\text{ribo}$-hexopyranosid-3-ulose with Me₃SiCN afforded methyl 2-acetamido-4,6-$\text{O}$-benzylidene-3-$\text{C}$-cyano-2-deoxy-3-$\text{O}$-trimethylsilyl-α-$\text{D}$-$\text{allo}$- Reaction of ethyl 4,6-di-$\text{O}$-acetyl-2,3-anhydro-α-$\text{D}$-mannopyranoside with Me₃SiCN gave the corresponding ethyl 4,6-di-$\text{O}$-acetyl-2-$\text{C}$-cyano-2-deoxy-α-$\text{D}$-glucopyranoside. Reaction of methyl 4,6-$\text{O}$-benzylidene-2,3-anhydro-α-$\text{D}$-allopyranoside or methyl 4,6-$\text{O}$-benzylidene-2,3-di-$\text{O}$-tosyl-α-$\text{D}$-glucopyranoside with Me₃SiCN at - 75° or - 50° gave the corresponding methyl 6-$\text{O}$-[(R)-cyano phenyl methyl]-α-$\text{D}$-glyco-pyranosides with high or total regio and stereoselectivity.     

Standard Enthalpies of Formation for Solid Complexes of Chromium Chloride with L—α—Amino Acids

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Synthesis,free-radical polymerization,and stereochemical configuration of methyl α-p-cyanobenzylacrylate

Methyl α-p-cyanobenzylacrylate was synthesized from dimethyl malonate following well-known organic reactions. The purified monomer was polymerized by a free-radical mechanism in benzene solution, using AIBN as initiator in the interval 50–90°C. The kinetic results seem to indicate an apparent ceiling temperature near 90°C. The analysis by ¹³C-NMR of polymers obtained indicates that the macromolecular chains are predominantly syndiotactic and the tacticity is independent of the polymerization temperature in the experimental interval studied. However, the determination of conditional probabilities for iso- and syndiotactic additions and the persistence ratios indicate that the propagation mechanism for the radical polymerization of methyl α-p-cyanobenzylacrylate does not follow a typical Bernoullian statistics.     

Synthesis and fluorescence of a series of multichromophoric acenaphthenyl compounds

A novel free radical trapping reaction based on a stepwise radical reversible addition-fragmentation mechanism has been utilized to synthesize a series of acenaphthenyl dimers and trimers. The synthetic procedure involves the reaction of acenaphthylene with dithiobenzoate compounds (S=C(Ph)-SR) in the presence of a free radical initiator followed by reduction of the dithiobenzoyl end group with tributyltin hydride. Stereoisomers of the compounds have been isolated and their structures determined by proton NMR and X-ray crystallography. The solution fluorescence of the compounds has been characterized to reveal the requirements for intramolecular excimer (excited-state dimer) formation. Only in compounds containing identical stereochemical arrangements of adjacent acenaphthenyl groups is excimer fluorescence observed following photoexcitation.