Structure of effective catalyst layers around bubbles in a fluidized catalyst bed

In a fluidized catalyst bed, the reactant gas transfers from the bubble phase to the emulsion phase and reactions proceed in the emulsion phase. The catalyst particles around the bubbles should contact the gases containing a high concentration of the reactants. Therefore, the effect of the catalysts around the bubbles is very important for estimating the conversion and selectivity in the reactor. In order to study the role of these catalysts, the hydrogenation of carbon dioxide was carried out in a fluidized catalyst bed. Based on the results, the amount of the catalyst that was effective for the reaction was calculated. In addition, the shape of the bubbles ascending in the fluidized catalyst bed was observed using a fast X-ray computer tomography (CT) scanner. The structure of the bubbles in the fluidized catalyst bed was very complicated and the surface area of the bubbles was much greater than the obtained when assuming spherical shaped bubble. By assuming that effective catalysts existed around the bubbles, the thickness of catalyst layer was obtained. Finally, the 3-dimensional images of the catalyst layers around the bubbles were reconstructed.     

Influence of Bile Salts on the Permeability Through the Nasal Mucosa of Rabbits of Insulin in Comparison with Dextran Derivatives

The nasal drug absorption and the effect of absorption promoters have been studied in rabbits. Nasal mucosa excised from rabbits was mounted as a flat sheet in an in vitro chamber. The result indicates that the change in the porosity of the membrane by pretreatment with bile salts increased the permeability coefficient of sodium chloride in the nasal membrane. The permeabilities of dextran derivatives were enhanced by pretreatment with sodium glycocholate (GC). The permeability coefficient (P) of fluorescein isothiocyanate diethylaminoethyl dextran     

Improvement of strength distribution inside slab concrete by vacuum dewatering method

The strength and hardness of concrete slab surface is considered significantly affected by bleeding of concrete. It has been reported that dewatering by vacuum processing is quite effective to obtain high density of concrete. The method, however, has not been successfully used for the concrete work in the field of building construction, compared with that of civil engineering works in Japan. In the present study, firstly the state of the art concerning vacuum dewatering method is reviewed and the newly improved vacuum dewatering method is introduced. Then the effect of the proposed method on concrete properties of slab is examined by a series of experiments in order to find more reasonable and effective way in the application of the proposed method.     

Improved Filtration Performance of Continuous Alumina-fiber-reinforced Mullite Composites for Hot-Gas Cleaning

The effect of filtration layer morphology on filtration performance at 673 K was investigated for continuous alumina-fiber-reinforced mullite composite filters that capture fly ash on their outer surfaces. Two types of filtration layers were prepared on the outer surfaces: a mono-layer consisting of mullite agglomerated particulates and a bi-layer, with mullite whiskers formed by a vapor-phase reaction and strongly adhered to the particulates exposed on the outer surfaces. For filters with mono-filtration layers, the filtration efficiency was improved slightly by increasing the filtration layer thickness. However, the maximum differential pressure increased during the filtration tests. Adhesion of whiskers to the outer surface decreased the maximum differential pressure to about one-third less than that with the mono-filtration layer. This low differential pressure remained constant throughout the duration of the test, with corresponding increases in filtration efficiency.     

Titanium aluminide coating on titanium surface using three-dimensional microwelder

Feasibility of a new method of titanium aluminide coating on titanium surface based on a reaction between aluminum liquid beads and the surface of titanium substrate has been studied using a computer-aided three-dimensional microwelder (3DMW) designed by the present authors. A predetermined length of thin aluminum wire was fed onto the substrate surface, and a spark was stricken from a thin electrode of a W-Ce₂O₃ alloy to make a small aluminum liquid bead on the substrate surface and to simultaneously melt a small area of the substrate surface beneath the bead. All conditions including the length of the wire feeding, the position of the electrode, electric power, etc. had been programmed beforehand. The liquid bead containing aluminum and titanium rapidly solidified on the titanium substrate surface producing titanium aluminides on it. Repetition of the aluminum wire feeding, the electrode positioning and the spark striking produced a coating layer consisting of sub-layers of TiAl₃, TiAl and Ti₃Al from the surface side to the substrate side. Vickers hardness and wear resistance of the coated sample were remarkably improved.     

Group Symmetry in Interior-Point Methods for Semidefinite Program

A class of group symmetric Semi-Definite Program (SDP) is introduced by using the framework of group representation theory. It is proved that the central path and several search directions of primal-dual interior-point methods are group symmetric. Preservation of group symmetry along the search direction theoretically guarantees that the numerically obtained optimal solution is group symmetric. As an illustrative example, we show that the optimization problem of a symmetric truss under frequency constraints can be formulated as a group symmetric SDP. Numerical experiments using an interior-point algorithm demonstrate convergence to strictly group symmetric solutions.     

Design of robotic behavior that imitates animal consciousness

A 6-degrees-of-freedom serial arm hand is controlled to move toward an object in an unseen environment. We developed a consciousness-based architecture (CBA), which is a hierarchical human development model representing the relationship between consciousness and behavior and is used for imitating a human groping action. During forward motion toward the object, a robot arm hand can help to avoid obstacles from which the robot collects contact information. The CBA organizes such information to learn a path plan for backward motion to the origin without contact with the obstacles. Experimental results show that the CBA successfully extends the hand to the goal while avoiding any obstacle. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007     

Fuzzy controller for AUV robots based on machine learning and genetic algorithm

Artificial Life and Robotics - Marine robots play a crucial role in exploring and investigating underwater and seafloor environments, organisms, structures, and resources. In this study, we...     

Dimeric C34 Derivatives Linked through Disulfide Bridges as New HIV-1 Fusion Inhibitors

C34, a 34-mer fragment peptide, is contained in the HIV-1 envelope protein gp41. A dimeric derivative of C34 linked through a disulfide bridge at its C terminus was synthesized and found to display potent anti-HIV activity, comparable with that of a previously reported PEGylated dimer of C34REG. The reduction in the size of the linker moiety for dimerization was thus successful, and this result might shed some light on the mechanism of the suppression of six-helix bundle formation by these C34 dimeric derivatives. Addition of a Gly-Cys(CH₂CONH₂)-Gly-Gly motif at the N-terminal position of a C34 monomeric derivative significantly increased the anti-HIV-1 activity. This moiety functions as a new pharmacophore, and this might provide a useful insight into the design of potent HIV-1 fusion inhibitors.     

Effects of solid lubricants in backward extrusion

In the present paper, some solid lubricants were tested in backward extrusion friction tests with flat-headed punches using aluminium at room temperature. The results showed that anti-seizure ability was improved when wax was added to the solid lubricant samples. In addition, a water-based graphite lubricant and an ultrahigh molecular weight polyethylene (UHMW-PE) lubricant were tested using aluminium workpieces heated to 500°C. The lubricity of the UHMW-PE lubricant was found to be superior to that of the graphite lubricant.