Ti–Pd Alloys as Heterogeneous Catalysts for Hydrogen Autotransfer Reaction and Catalytic Improvement by Hydrogenation Effects

Ti−Pd alloys were investigated as heterogeneous catalysts for hydrogen autotransfer reactions. This is the first reported study of alloys as catalysts for hydrogen‐borrowing reactions using alcohols. We improved the catalytic activities of alloys by increasing their specific surface areas via a hydrogenation−powdering process. The reactivities and selectivities of hydrogenated Ti−Pd alloys [Ti−Pd (Hy) ] were higher than those of non‐hydrogenated alloy catalysts in N‐alkylation by hydrogen autotransfer using alcohols. A plausible catalytic cycle is proposed based on control studies and deuterium labelling experiments

Reaction kinetics of muonium with the halogen gases (F2, Cl2, and Br2)

Copyright @ 1989 American Institute of PhysicsBimolecular rate constants for the thermal chemical reactions of muonium (Mu) with the halogen gases—Mu+X2→MuX+X—are reported over the temperature ranges from 500 down to 100, 160, and 200 K for X2=F2,Cl2, and Br2, respectively. The Arrhenius plots for both the chlorine and fluorine reactions show positive activation energies Ea over the whole temperature ranges studied, but which decrease to near zero at low temperature, indicative of the dominant role played by quantum tunneling of the ultralight muonium atom. In the case of Mu+F2, the bimolecular rate constant k(T) is essentially independent of temperature below 150 K, likely the first observation of Wigner threshold tunneling in gas phase (H atom) kinetics. A similar trend is seen in the Mu+Cl2 reaction. The Br2 data exhibit an apparent negative activation energy [Ea=(−0.095±0.020) kcal mol−1], constant over the temperature range of ∼200–400 K, but which decreases at higher temperatures, indicative of a highly attractive potential energy surface. This result is consistent with the energy dependence in the reactive cross section found some years ago in the atomic beam data of Hepburn et al. [J. Chem. Phys. 69, 4311 (1978)]. In comparing the present Mu data with the corresponding H atom kinetic data, it is found that Mu invariably reacts considerably faster than H at all temperatures, but particularly so at low temperatures in the cases of F2 and Cl2. The current transition state calculations of Steckler, Garrett, and Truhlar [Hyperfine Interact. 32, 779 (986)] for Mu+X2 account reasonably well for the rate constants for F2 and Cl2 near room temperature, but their calculated value for Mu+Br2 is much too high. Moreover, these calculations seemingly fail to account for the trend in the Mu+F2 and Mu+Cl2 data toward pronounced quantum tunneling at low temperatures. It is noted that the Mu kinetics provide a crucial test of the accuracy of transition state treatments of tunneling on these early barrier HX2 potential energy surfaces.NSERC (Canada), Donors of the Petroleum Research Fund, administered by the American Chemical Society, for their partial support of this research and the Canada Council

ZZ-Branes of N=2 Super-Liouville Theory

We study conformal boundary conditions and corresponding one-point functions of the N=2 super-Liouville theory using both conformal and modular bootstrap methods. We have found both continuous (`FZZT-branes') and discrete (`ZZ-branes') boundary conditions. In particular, we identify two different types of the discrete ZZ-brane solutions, which are associated with degenerate fields of the N=2 super-Liouville theory.Comment: 26 page

Boundary Action of N=2 Super-Liouville Theory

We derive a boundary action of N=2 super-Liouville theory which preserves both N=2 supersymmetry and conformal symmetry by imposing explicitly $T={\bar T}$ and $G={\bar G}$. The resulting boundary action shows a new duality symmetry.Comment: 15 pages; One reference is adde

Fed batch production of hydrogen from palm oil mill effluent using anaerobic microflora

Anaerobic production of hydrogen from palm oil mill effluent (POME) by microflora was investigated in 5-l bioreactor at 60 °C and pH 5.5. POME sludge was collected from the anaerobic pond of a POME treatment plant at a palm oil mill and used as a source of inocula. A batch reactor was found to yield a total of 4708 ml H2H2/(l POME) and the maximum evolution rate was 454 ml-H2H2/(l POME h). A fed batch process was conducted after 50 h. Two liters of reaction medium was removed and 2 l of fresh POME was added to the reactor every 24 h (15 times). The reproducibility of the fed batch process checked by changing the feeding time every 8 h (10 times). A yield of 2382 ml H2H2/(l POME) and 2419 ml H2H2/(l POME) at maximum evolution rate of 313 ml H2H2/(l POME h) and 436 ml H2H2/(l POME h) were obtained, respectively. Throughout the study, methane gas was not observed in the evolved gas mixture

Performance of Repulsive Type Magnetic Bearing System Under Nonuniform Magnetization of Permanent Magnet

Permanent magnet bearing system utilizes the repulsive forces between the stator and rotor permanent magnets (PM) for the levitation of the system and it results a simplified axial control scheme. A repulsive type magnetic bearing system based on the above principle was fabricated in our laboratory. Material characteristics and the configuration of the permanent magnets are the central component for this type of bearing system. Due to aging or as both the magnets are repelling each other, there will be demagnetization of the permanent magnet, resulting the field distribution along the magnet\u27s periphery nonuniform. In this paper the effect of this magnetization nonuniformity on the performance of the bearing system has been studied

Measurement and Visualization of Three-Dimensional Radial and Vectored Magnetic Field Distribution by Usue of the Magnetic CT Method

金沢大学環日本海域環境研究センター生体機能計測研究部