Pt-supported Spherical Mesoporous Silica as a Nanosized Catalyst for Efficient Liquid-Phase Hydrogenation

Mesoporous silica nanospheres with an average diameter of approximately 240 and 600 nm have been used as catalyst supports of active Pt nanoparticles, which were found to be highly efficient for liquid-phase hydrogenation under atmospheric H₂ compared to the micron-sized conventional mesoporous silica because of the suppression of mass-transport limitation toward active sites.     

Dissolution behavior of core structure materials by molten corium in boiling water reactor plants during severe accidents

For the decommissioning of the Fukushima Daiichi Nuclear Power Plant, it is necessary to consider the access route to the fuel debris for its removal, which can be determined by knowing the corruption situation of the core support structure. To predict the damage condition of reactor vessel, dissolution behavior of the core structure material should be understood. In this study, the dissolution behavior of core structure materials (stainless steel) by molten metallic corium (stainless steel + B₄C) originated from control rod and its cladding was investigated. As a result of immersion experiment, it was found that there were two types of dissolution mode in this system: (1) chemical dissolution by eutectic reaction between Fe and B and (2) physical dissolution caused by the grains falling off from solid steel due to infiltration of molten metal. Moreover, on the basis of kinetic analysis, it was considered that the chemical dissolution in this system was slow. Therefore, the dissolution is considered to mainly occur through the mechanism that physical dissolution precedes chemical dissolution.     

Pore formation in p-type silicon in solutions containing different types of alcohol

ABSTRACT: Macroporous structure of silicon can be obtained with anodization in HF solution. The macropore formation in the presence of alcohol was studied. Macroporous layer formation in a low-concentration HF solution is stabilized with increasing the number of carbon in alcohol. Dissolution at the topmost part of the porous layer is observed though the behavior depends upon the type of alcohol. Meanwhile the total mass loss of dissolved silicon is almost constant. Such dissolution at the top surface occurs only when the concentration of HF is low. Adding organic solvents to the HF solution also leads to the suppression of the pore wall dissolution. The type of alcohol and HF concentration in solution affect the formation of porous silicon.     

A convenient synthesis of long-chain 1-O-Alkyl glyceryl ethers

A convenient and economical procedure for synthesis of long-chain 1-O-alkyl glyceryl ethers (V) is described. Alkyl glycidyl ethers (II) which were derived from the reaction of alcohols (I) with epichlorohydrin using a phase transfer catalyst were first converted into the corresponding dioxolanes (III) or 1-O-alkyl-2,3-di-O-acetylglycerols (IV). Subsequent hydrolysis of the resultant products provided 1-O-alkyl glyceryl ethers (V) in high yields.     

Molecular dynamics study on nano‐particles reinforced oxide glass

Energy release rate and fracture toughness of amorphous aluminum nanoparticles reinforced soda‐lime silica glass (SLSG) were measured by performing fracture simulations of a single‐notched specimen via molecular dynamics simulations. The simulation procedure was first applied to conventional oxide glasses and the accuracy was verified with comparing to experimental data. According to the fracture simulations on three models of SLSG/‐Al₂O₃ composite, it was found that the crack propagation in the composites is prevented through following remarkable phenomena; one is that a‐Al₂O₃ nanoparticles increase fracture surface area by disturbing crack propagation. The other is that the deformation of a‐Al₂O₃ nanoparticle dissipates energy through cracking. Moreover, one of the models shows us that the crack cannot propagate if the initial notch is generated inside a‐Al₂O₃ nanoparticle. Such strengthening is partly due to the fact that the strength of the interface between nanoparticle and SLSG matrix is comparable to that of SLSG matrix, implying that their interface does not reduce crack resistance of the oxide glass.     

The alkyl glycidyl ether as synthetic building blocks

Alkyl glycidyl ether is one of the most useful key materials for industrial applications because the addition reaction of various kinds of nucleophilic reagents to the reactive epoxy bond of the glycidyl ethers has led to glyceryl ether derivatives. Glyceryl ether exhibits many interesting physical and pharmacological properties. The alkyl glycidyl ether can presently be produced at an industrial scale under the phase-transfer catalytic Williamson ether synthesis. We have reviwwed some addition reactions of the alkyl glycidyl ether and possibilities for use as the building blocks for the syntheses of surfactants, pharmaceuticals, etc. that contain glyceryl ether skeletons. Typical examples of alkyl glyceryl ether derivatives include: amino ether as cosmetic material, and isodiglycerin mono- and dialkyl ethers and triglycerin monoalkyl ether as a cosmetic or a pharmacologically useful material, respectively. Another interesting reaction is the rearrangement of the epoxy bond of the alkyl glycidyl ether, which gives alkoxy ketone in a one-pot synthesis.     

Unique block molecules based on glycerol skeleton as C‐3 building blocks for liquid crystals formation by self‐assembly and their future potential for the “nano‐chemistry”

Studies on design of liquid crystalline block molecules with non‐conventional mesophase morphoplogies have been proposed by Tschierske and co‐workers. These block molecules have a rigid core, a lateral substituent, and an alkyl chain segmenting blocks from each other. Related to this, diglyceryl alkyl ethers found by us have glycerol as a rigid core, a lateral substituent, and an alkyl chain similar to the Tschierske design. These two cases are compared with each other with regard to the relationship between the molecular structure and the liquid crystalline morphologies and other properties. Recently, new soft materials suitable for liquid crystals exhibiting self‐assembly of phase‐segregated structures have been designed. Typical examples of such “block” molecules containing glycerol having a C‐3 building block include: (i) undecyl‐glycerylether‐ modified siloxane derivatives with a siloxane segment as the rigid core and alkyl chains with 2, 3‐dihydroxypropoxy group as a hydrophilic group at a lateral or terminal position of the siloxane segment; (ii) novel hyper branched dendrimers forming the basis of polyglycerol nanocapsules with a core‐shell molecular architecture; (iii) carbon nanotubes based on cyclodextrins (CDs); (iv) polymerizable amphiphilic diacetylene‐containing phospholipids suitable for construction of functional nanocomposites. This is done by self‐assembly and polymerization of diacetylene creating a “block molecular structure” with a polyacetylene chain as a rigid core segment, the lipid headgroups as the hydrophilic segment, and terminal flexible alkyl chains. On the basis of these results, future potential of block molecules as a soft building material for liquid crystalline structures was discussed.     

Melatonin treatment for circadian rhythm sleep disorders

We administered 1-3 mg melatonin to 11 patients (eight men, three women, aged 16-46 years) with circadian rhythm sleep disorders; nine with delayed sleep phase syndrome and two with non-24-hour sleep-wake syndrome. Sleep logs were recorded throughout the study periods and actigraph and rectal temperature were monitored during treatment periods. Melatonin was administered 1-2 h before the desirable bedtime for expected phase-shifting, or 0.5-1 h before habitual bedtime for gradual advance expecting an hypnotic effect of the melatonin. Melatonin treatments were successful in 6/11 patients. Timing and dose of melatonin administration, together with its pharmacological properties for circadian rhythm sleep disorders, should be further studied.     

Progress in Physics and Technology Developments for the Modification of JT-60

Recent progress in the physics and engineering design study for the modification programme of JT-60 is presented. In order to achieve a steady state high-β plasma operation, which is the dominant issue of this programme, physics design for the MHD control and the stability analysis is investigated. Engineering design and the R & D for the superconducting coils, irradiation shield are performed well towards the mission of programme.