On the Broadwell model of the Boltzmann equation for a simple discrete velocity gas

The Broadwell model of the Boltzmann equation for a simple discrete velocity gas is investigated on two asymptotic problems. (a) The decay of solutions inxR ast+. (b) The hydrodynamical limit in the compressible Euler level as the mean free path0.     

Selective hydrogenolysis of the benzyl protecting group for hydroxy function with raney nickel in the presence of the MPM (4-methoxybenzyl) and DMPM (3,4-dimethoxybenzyl) protecting groups

The benzyl protecting group for hydroxy function was selectively removed by catalytic hydrogenolysis with Raney nickel in the presence of the MPM (4-methoxybenzyl) and DMPM (3,4-dimethoxybenzyl) protecting groups, and applied to the synthesis of some synthons to macrolide and polyether antibiotics.     

Active control of methanol carbonylation selectivity over Au/carbon anode by electrochemical potential

Electrochemical oxidative carbonylation of methanol was studied over Au supported carbon anode in CO. The major carbonylation products were dimethyl oxalate (DMO) and dimethyl carbonate (DMC). The minor oxidation products were dimethoxy methane (DMM) and methyl formate (MF) from methanol and CO(2). Influences of various reaction conditions were studied on carbonylation activities and selectivities. The selectivities to DMO and DMC can be controlled by the electrochemical potential. Electrocatalysis of Au/carbon anode was studied by cyclic voltammetry (CV), stoichiometric reactions among Au(3+), methanol, and CO, and UV-vis spectra. The Au/carbon anode was characterized by XRD, SEM, and BE images before and after the carbonylation. These experimental facts strongly suggest that transition of oxidation states of Au affects changing of the carbonylation selectivities to DMO and DMC. Au(0) is the active species for the selective DMO formation by direct electrochemical carbonylation at low potentials (<+1.2 V (Ag/AgCl)). On the other hand, Au(3+) is the active spices for the selective DMC formation by indirect electrochemical carbonylation through Au(3+)/Au(+) redox at high potentials (>+1.3 V).     

Determinations of citric acid by differential pulse polarography with immobilized enzymes

Summary Citrate lyase and oxaloacetate decarboxylase can be rapidly and simply immobilized in polyacrylamide gel to provide a selective and sensitive reactor. Conversion ratio of citric acid to pyruvic acid comes up to 90% under the optimal conditions. Generated pyruvic acid can be determined by differential pulse polarography. The bioreactor can be used for thirty determinations over several weeks. Samples of sports drinks and wine were successfully tested without pretreatment; the relative standard deviation with 1.0×10^-5 mol l^-1 citric acid in polarographic solutions was 1.17% and the detection limit was 6.6×10^-7 mol l^-1 (=2).     

A chiral ligand-mediated asymmetric addition of a lithium BHA ester enolate to an aldehyde

The asymmetric reaction of a lithium enolate generated from a BHA (2, 6-di-tert-buty-4-methoxyphenyl) propanoate was allowed to react with benzaldehyde in the presence of a diether-type chiral ligand affording the corresponding anti-aldol product in a moderate enantioselectivity. A tetradentate ligand induced better enantioselectivity albeit relative loss of anti-selectivity. A variation of lithiating amide agent affected the selectivity, indicating involvement of an amine as a component of the mixed aggregate. Absolute configuration of some of the aldol products was determined by standard transformations.     

Synthesis and reactions of 1,2-fused 3-cyanoindolizines

With the intention that annulation of carbo- or heteroaromatic rings at the 1,2-positions can activate 3-cyanoindolizines as 1,3-dipolar species, 6-cyanobenz[a]indolizines, pyridazino[4,5-a]indolizines and 5-cyano-1,3-diphenylthiopheno[3,4-a]indolizine were prepared. 6-Cyanobenz[a]indolizines smoothly -underwent 1,3-dipolar cycloaddition on to dibenzoylacetylene and diacetylacetylene to afford the corresponding indolizino[3,4,5-ab]isoindoles, whereas 5-cyano-1,4-diphenylpyridazino[4,5-a]indolizine reacted with dimethyl acetylenedicarboxylate to give the 1:2 adduct. Only a 3% yield of 5-cyano-1,3-diphenylthiopheno[3,4-a]indolizine formed upon phosphorus pentasulfide treatment of 1,2-dibenzoyl-3-cyanoindolizine.     

A CSF-based multireference coupled pair approximation

Summary MRCPA (multireference coupled pair approximation) is formulated by the use of the wave operator formalism and Rayleigh-Schrödiner perturbation theory with special selection of the unperturbed part of the electronic Hamiltonian. By considering super molecule, it is shown that the theory is size consistent with the help of the new formalism. The method has been tested for three simple systems, H₂O, FH, and O₂.     

Determination of electrochemical kinetic parameters from the measurement of faradaic impedance during the growth of the dropping mercury electrode

The electrochemical kinetic parameters of the V(II)/V(III) couple in HBr solutions of different concentrations were determined from the measurement of faradaic impedance as a function of time during the growth of the dropping mercury electrode. The same method of analysis was applied to the study of the effect of uncharged surfactants on the electrode reaction of Cd(II) in 1 M NaNO₃ solutions. The rate constant of the vanadium system decreased with increasing concentration of HBr; this change of the rate constant was discussed in terms of the Frumkin double-layer effect. The relationship between the rate constant of Cd(II) and coverage of the surfactants was not linear, and followed the equation based upon Parsons' model of the blocking effect. The conditional rate constant of Cd(II) in the absence of surfactants was determined to be 0.6–1.1 cm s^?1 from the dependence of the rate constant on the coverage.     

Copper L X-ray spectra measured by a high resolution ion-induced X-ray spectrometer

High resolution L X-ray emission spectra of Cu have been measured by 0.75 MeV/u H, He, and F, 0.73 MeV/u Ar, 0.64 MeV/u Si, and 0.073 MeV/u Si ion impacts with a crystal spectrometer. The X-ray transition energies in the Cu target for Lι, Lη, L_1,2, Lβ₁, and Lβ_3,4 diagram lines induced by H ion impact are determined, which are in good agreement with those given in the reference by Bearden (Rev. Mod. Phys. 39, 78, 1967). The X-ray spectra produced by F, Si, and Ar ions have complicated structures due to multiple L and M shell vacancy production. The L_1,2 and Lβ₁ emission spectra for H and He ions are compared with the calculated ones based on the multiconfiguration Dirac-Fock method. The origin of the broadening of the L_1,2 line to the lower energy for H ion impact is attributed to one 2p plus one 3d electron vacancy production.     

Application of fragment molecular orbital scheme to silicon-containing systems

The fragment molecular orbital (FMO) scheme has been successfully used for a variety of large-scale molecules such as proteins and nucleic acids so far. We have applied the FMO calculations to the silicon-containing systems like polysilanes. The error caused by the fragmentation was examined by the Hartree–Fock method and the second-order Møller-Plesset (MP2) perturbation method for the ground state energy. The dynamic polarizability as a linear response property was also evaluated with and without the fragmentation. A series of numerical comparisons showed that the FMO scheme is applicable to silicon-based molecules with reasonable accuracy. This implied a potential availability of FMO calculations for the issues relevant to nanoscience and nanotechnology.