[en] Ruthenium catalysts supported on SiO₂, Al₂O₃ and TiO₂ were prepared by the impregnation method. Temperature-programmed desorption (TPD) method was applied to investigate the kinetics of hydrogen adsorption/desorption on these catalysts. All the TPD results show two-peak profile, except Ru/SiO₂. The low-temperature peak was assigned to the hydrogen adsorbed on the Ru metal. The high-temperature peak was attributed to the spillover of hydrogen atoms from metal to the support. Both are activated process. The amount of adsorbed hydrogen increased with increasing adsorption temperature, and the maximum adsorption occurs at above 200 deg. C. The activation energy of adsorption is a function of catalyst support and the reduction temperature. It decreases in the order of Ru/TiO₂ (500 deg. C reduction)>Ru/Al₂O₃>Ru/TiO₂ (300 deg. C reduction)>Ru/SiO₂. The results demonstrated that the strong metal-support interaction exerted on Ru/TiO₂ would suppress hydrogen chemisorption at room temperature due to its high activation energy. However, hydrogen chemisorption on Ru/TiO₂ was not suppressed at high temperature. One is able to measure the Ru dispersion by adsorption of hydrogen at high temperature

[en] The purpose of this article is to propose both state and time-dependent preventive maintenance policy for a multi-state deteriorating system, which is equipped with inspection equipment(s) connected to a computer center. After the system being identified as state x at nd through computation by the computer center after inspection (or measurement) via equipment(s), one maintenance action with the minimum expected total cost since nd till Nd (where N=n+K for a fixed integer 0< K<∞) will be chosen from the set A_x of alternatives also with the help of the computer center. In real case, the expected total costs since nd till Nd will be time-dependent and so is the maintenance action chosen at nd. A numerical example is given to illustrate such a maintenance policy for a Markovian deteriorating system to describe its state dependent aspect only for simplicity reason. Due to the fact that both equipment measurement and computer computation take time, the preventive maintenance policy for a sufficiently small d may be used in fact as the one under continuous inspection

[en] Self-organization of nano-size spherical particles in opal-like structures has been demonstrated to be a powerful mean to build three-dimensional (3D) photonic crystal. We here present a simplified sedimentation process leading to photonic crystal layer with a non-absolute bandgap in the visible range. The stacking organization is cross checked directly by classical optical microscopy (COM), atomic force microscopy (AFM) and scanning electron microscopy (SEM), giving a detailed scheme of the short range and long range organization, and indirectly by reflection/transmission spectroscopy for different incidence angles. The results show a very good resonance associated with a low cost deposition technique. The implementation of our method for further application like photonic waveguides is also discussed

[en] When the intense laser pulse propagates in the atomic vapor over a long distance, the laser pulse shape, the carrier frequency and the propagating velocity are greatly modified during the propagation by the resonant and/or the near-resonant interactions with atoms. We have been investigating these effects on the laser beam propagation experimentally and analytically. The simulation code named CEALIS-P has been developed, which employs the coupled three- level Bloch-Maxwell equations to study the atomic excitation and laser beam propagation simultaneously. Several features of the resonant and near-resonant effects based on the the self-induced transparency, the self-phase modulation and the nonlinear group velocity dispersion are described and the influences of such effects on the photoionization efficiency are analyzed.

[en] The effects of inert particles on the liquid hydrogenation over nano-sized Ni-B catalysts were investigated in a batch reactor. Nitrobenzene hydrogenation was used as a test reaction. The effects of stirring speed and the dispersant/catalysts ratio were investigated. Addition of inert particle in the reaction system of nano-catalysts could increase the reaction conversion significantly. The reaction conversion increased with increasing stirring speeding until 900-rpm, and then decreased. The addition of inert particle to the reaction system could prevent the agglomeration of nano-metals and disperse them over the entire reaction system. Nano-metals were physically attached on the external surface of the inert particles. In addition, the addition of inert particle may enhance the absorption rate of hydrogen in solvent, and resulting in the increase of reaction rate. Both are beneficial to the reaction conversion. The enhancement effect of Al₂O₃ is much greater than that of SiO₂

[en] A series of NiP_xB_y nanomaterials were prepared by a chemical reduction method under various preparation parameters. Experiment results show that the different preparation parameters affected the morphology, particle size, surface area and the composition of the sample. However, they did not influence the electronic state of nickel. The type of solution showed significant influence on the properties of the sample, whereas, the type of nickel salt did not. The particle size of NiPB, NiB, and NiP were 10-30 nm. The NiP sample prepared in the aqueous solution had the largest particle size 50-150 nm. If the solvent was 50% ethanol in water, the surface area of the sample significantly increased nine fold for NiP and four fold for NiPB powders. In contrast, the surface area of NiB did not increase. The NiPB, NiB, and NiP powders had a spherical morphology if they were prepared with aqueous solution. The NiPB prepared in 50% ethanol solution showed floss morphology and had a very high surface area

[en] Atomic vapor laser isotope separation (AVLIS) is a process which uses intense pulsed lasers to selectively photoionize one isotopic species of a chemical element, after which these ions are extracted electromagnetically. The AVLIS has several advantages over the traditional methods based on the mass difference, such as high selectivity, low energy consumption, short starting time and versatility to any atoms. The efforts for atomic vapor laser isotope separation at ILT and ILE, Osaka University have been concentrated into the following items: 1) studies on laser spectroscopy and laser isotope separation of atomic gadolinium, 2) studies on interaction processes including coherent dynamics, propagation effects and atom-ion collision in AVLIS system, 3) development of laser systems for AVLIS. In this paper, we present experimental results on the laser spectroscopy and laser isotope separation of atomic gadolinium.

[en] Electrosorption of ions from aqueous solutions with carbon nanotubes and nanofibers (CNTs-CNFs) composite film electrodes has been demonstrated. The large area CNTs-CNFs film was directly grown on Ni plate by low pressure and low temperature thermal chemical vapor deposition. The CNTs-CNFs electrodes have great advantages such as low cost, easy operation, long-term reproducibility, and integrity of monolithic CNTs-CNFs film and current collector. Batch-mode experiments at low voltage (0.4-2 V) were conducted in a continuously recycling system to investigate the electrosorption process. Purification of water with good reproducibility was achieved because of optimal pore size distribution of CNTs-CNFs composite films

[en] Refractory high entropy alloys (RHEAs), with excellent properties at high temperature, have several applications. In this work, the ZrTiHfNbMo_x (x=0.5, 1.0, 1.5) alloys were prepared by arc melting. All these alloys form body centered cubic (BCC) structure without other intermediate phases. The Mo element contributes to the strength of alloys at high temperature, but too much of Mo decreases the plasticity severely and enhances the strength. The ZrTiHfNbMo alloy, whose compressive stress is 1099 MPa at 800° C, is a promising material for high-temperature applications. (paper)

[en] A method to prepare iron oxide material which has a higher surface area and nanosized particle was developed. It was used as a catalyst for CO oxidation at low temperature. Iron oxide materials were prepared by precipitation under constant pH value. The effects of preparation parameters, such as iron salt (FeCl₃, Fe(NO₃)₃ and FeCl₂), pH value (between 8 and 12), drying temperature (between 120 deg. C and 300 deg. C), and feeding rate of the aqueous solution of the iron salt, on the characteristics of iron oxide have been investigated. The materials were characterized by N₂ sorption, powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The surface area of iron oxide was greater than 400 m²/g using FeCl₃ as the starting material with very low feeding rate of 10 ml/min, the pH value of 11, and drying at 120 deg. C. The XRD patterns indicated that the iron oxide samples heated at a temperature below 180 deg. C was either amorphous or of a particle size too small (<4 nm) for the samples prepared with FeCl₃. Depending on the preparation conditions, the iron oxide samples showed a phase transition from amorphous to various crystalline phases. Large amount of hydroxyl groups were preserved if the drying temperature was below 200 deg. C. TEM images showed that the particle diameters were less than 4 nm for the samples prepared with FeCl₃ at pH value of 11 with a low feeding rate of 10 ml/min, and heated below 200 deg. C. XPS Fe 2p_3/2 spectra showed the phase transition of iron oxide from Fe₃O₄ to FeO. The feeding rate of starting material and pH value during precipitation played the important roles to obtain iron oxide with high surface area. The nanosized iron oxide demonstrated high activity for CO oxidation even at ambient condition. The higher activity of Fe_xO_y nanoparticles in CO oxidation was attributed to a small particle size, high surface area, high concentration of hydroxyl groups, and more densely populated surface coordination unsaturated sites