An open 4-manifold having no instanton

Taubes proved that all compact oriented Riemannian 4-manifolds admit non-flat instantons. We show that there exists a non-compact oriented complete Riemannian 4-manifold having no non-flat instanton.     

Sorption and diffusion behaviours of strontium in sodium-type bentonite bed

Sorption and diffusion of Sr were examined using a typical Japanese bentonite. The experimental results showed that Sr sorption on the bentonite had linear relationship between the equilibrium Sr concentration and Sr sorption amount, i.e., Henry’s type of sorption, in wide initial Sr concentration from 1.1 × 10^?9 to 1.1 × 10^?4 mol L^?1 at pH 10. The Sr sorption also indicated pH dependence in pH range between 2 and 12. Sorption modelling calculation indicated that cation-exchange reactions contributed to Sr sorption in the pH range studied and a surface complexation reaction was predominant above pH 8. Diffusion of Sr in loosely compacted bentonite bed was described by pore and surface diffusion and surface complexation of Sr. Chemical-transport calculations reproduce the diffusion data at pH 5 using the cation-exchange parameters obtained in the analysis of the batch sorption experiment.     

Vector Bundle-Valued Poisson and Cauchy Kernel Functions on Classical Domains

In this paper we investigate the vector bundle-valued Cauchy and Poisson kernel functions. We compute explicitly matrix-valued eigenfunctions of an invariant differential operator on the classical domain of Type I. Furthermore, a special choice of a vector bundle gives us a matrix-valued Cauchy and Poisson kernel function which satisfies the matrix-valued Laplacian operator on the classical domain of Type I.     

EXAFS study of U(VI) uptake by calcium silicate hydrates

Among the different cement minerals, calcium silicate hydrates (C-S-H) are the prime candidates for heavy metal binding because of their abundance and appropriate structure. Immobilization processes of heavy metals by cementitious materials, and in particular C-S-H phases, thus play an important role in multibarrier concepts developed worldwide for the safe disposal of hazardous and radioactive wastes. In this study, the uptake of U(VI) by C-S-H has been investigated using X-ray absorption fine structure (XAFS) spectroscopy. C-S-H phases were synthesized using two different procedures: One is based on the mixing of CaO and SiO2 solids ("direct reaction" method); for the other one starting solutions of Ca and Si are used ("solution reaction" method). XAFS investigations were carried out on samples doped with U(VI). U(VI) was either sorbed onto previously precipitated C-S-H phases (sorption samples) or added during C-S-H synthesis (coprecipitation samples). The coordination environment of U(VI) in the sorption samples was found to be independent of the procedure used for C-S-H synthesis. A split equatorial oxygen shell (Oeq1: R=2.23-2.27 A; Oeq2: R=2.36-2.45 A), neighboring silicon atoms at short (R=3.07-3.11 A) and long (R=3.71-3.77 A) distances, and neighboring Ca atoms (R=3.77-3.81 and 4.15-4.29 A) were observed for all the samples. The structural parameters resemble those reported for uranophane. The coordination environment of U(VI) in the coprecipitation samples depends on the method used for C-S-H synthesis, and further, the spectra differ from those determined for the sorption samples. UU backscattering contributions were observed in the samples prepared using the direct reaction method, whereas no split equatorial shell appeared in the samples prepared using the solution reaction method.     

Effect of octabromination of a tetrakis(4-carboxyphenyl)porphine derivative bound to silica gels on HPLC retention behaviors of polyaromatic hydrocarbons

The effect of bromination of Cu-porphyrin-derivative-immobilized silica gels (Cu-TCPP_D) was examined by comparing the retention behaviors of polyaromatic hydrocarbons (PAHs) on Cu-TCPP_D and Cu-octabromotetrakis(4-carboxyphenyl)porphine-derivative-immobilized silica gels (Cu-OBTCPP_D) columns. It was revealed that bromination affects strongly the π–π electron interactions caused from hydration energy in a polar eluent (80% methanol) possibly as a result of a destruction of planar structure of porphine-ring by bromination. It was also revealed that bromination enhances π–d interactions as well as the π–π electron interactions in a broad sense (e.g., dispersion forces) in a non-polar eluent (n-hexane). However, the bromination did not exert much influence on electrostatic interactions caused from polarization of mono-halogenated benzenes.     

Palladium(0)-catalyzed alkylative cyclization of alkynals and alkynones: remarkable trans-addition of organoboronic reagents

Palladium/monophosphine complexes catalyze trans-selective arylative, alkenylative, and alkylative cyclization reactions of alkynals and alkynones with organoboronic reagents. These reactions afford six-membered allylic alcohols with endo-tri- or tetrasubstituted olefin groups and/or five-membered counterparts with exo olefin groups. The ratios of these products are dramatically affected by alkyne substituents as well as the phosphine ligand. The remarkable trans-selectivity of the process results from the novel reaction mechanism involving oxidative addition without oxametallacycle formation.     

Production of nitric monoxide using pulsed discharges for a medicalapplication

Nitric monoxide (NO) is widely used in medical treatment of acute respiratory distress syndrome (ARDS). The production of NO is of interest to the medical community. In the present work, NO is generated by pulsed discharges between two rod electrodes in a mixture of nitrogen and oxygen. An arc discharge having a temperature of about 10000 K was produced, which was sufficient to generate NO. Some of the important parameters affecting the production of NO have been investigated. These include the percentage of O₂ (6-94%) in the mixture of Na and O₂, the energy of the discharge (0.5-12 J/pulse), the pulse repetition rate (0.54.5 pps) and the flow rate (1.35-5.4 l/min) of the gas mixture. NO₂ produced in the discharge was successfully changed to NO using a heated molybdenum tube, NO₂ must be extracted from the gas before clinical inhalation. The concentration of ozone was completely eliminated by bubbling the gas mixture through water. A maximum of NO and a minimum of NO₂ concentrations were generated when the proportion of O₂ in the gas mixture was in the range of 20-27%. The concentrations of NO and NO₂ increased with increasing pulse repetition rate and with decreasing flow rate of the mixture. In all cases, No₂ was effectively removed using a heated molybdenum tube