Preparation of Aragonite Whiskers

A simple synthetic method for preparing aragonite whiskers has been developed. A suspension of CaCl₂-MgCl₂-Mg(OH)₂ with pH ∼9 has been prepared by adding Ca(OH)₂ to MgCl₂ aqueous solution. CaCO₃ whiskers (aragonite phase) have been prepared easily by blowing CO₂-containing gas into the suspension. The whiskers have high aspect ratios ranging from 20 to 80 with diameters of 0.5–1 μm .     

Anodic Dissolution of Uranium Mononitride in Lithium Chloride-Potassium Chloride Eutectic Melt

Uranium-plutonium nitride is a candidate fuel for fast reactors, but its major drawback is ¹⁴C formation from natural nitrogen. One would probably have to use highly ¹⁵N-enriched nitrogen. A pyrochemical process with molten-salt electroreflning has been proposed as a means to increase the nuclear proliferation resistance of the fuel cycle. Molten-salt electroreflning could also be applied to nitride fuels to make possible the recycling of ¹⁵N. The anodic dissolution behavior of UN in LiCI-KCI melt was studied to provide the basis for a feasibility study of electroreflning of irradiated nitride fuels.     

Monte Carlo simulation of the sol-gel process for the hydrolysis and polycondensation of tin tetra-n-butoxide

The sol-gel process for the hydrolysis and polycondensation of tin tetra-n-butoxide in butanol was followed by viscosity measurements. The precipitation of tin-containing ultrafine particles was observed without any variation in the solution viscosity in the absence of diethylene glycols, while the viscosity increase was made without any precipitation by the addition of diethylene glycol. The induction period and the rate of the viscosity increase after the induction period was independent of the diethylene glycol content but depended upon the water content. The Monte Carlo simulation data were consistent with data for the viscosity experiment. The simulation was based on a kinetic model of the slow hydrolysis of tin tetra-n-butoxide, the reverse reaction of hydrolysis, and the polycondensation of the hydroxy derivatives.     

Processing of Silicon Carbide-Mullite-Alumina Nanocomposites

Nanocomposite materials in the form of nanometer-sized second-phase particles dispersed in a ceramic matrix have been shown to display enhanced mechanical properties. In spite of this potential, processing methodologies to produce these nanocomposites are not well established. In this paper, we describe a new method for processing SiC-mullite-Al₂O₃ nanocomposites by the reaction sintering of green compacts prepared by colloidal consolidation of a mixture of SiC and Al₂O₃ powders. In this method, the surface of the SiC particles was first oxidized to produce silicon oxide and to reduce the core of the SiC particles to nanometer size. Next, the surface silicon oxide was reacted with alumina to produce mullite. This process results in particles with two kinds of morphologies: nanometer-sized SiC particles that are distributed in the mullite phase and mullite whiskers in the SiC phase. Both particle types are immersed in an Al₂O₃ matrix.     

Tantalum powder production by magnesiothermic reduction of TaCl5 through an electronically mediated reaction (EMR)

Tantalum powder production by magnesiothermic reduction of tantalum pentachloride (TaCl₅) through an electronically mediated reaction (EMR) has been examined. Feed material, TaCl₅, and reductant magnesium alloy were charged into electronically isolated locations in the molten salt (e.g. NaCl–KCl–MgCl₂) at 1073 K. After providing external path for electron flow, the current flow between the feed and the reductant locations was monitored. A large current, more than 1 A, was detected during the reaction and tantalum powder with low nickel and silver content was obtained, although liquid Mg–Ag–Ni alloy was used as the reductant. This clearly demonstrates that tantalum powder can be produced by electronically mediated reaction (EMR) without direct physical contact between the feed (TaCl₅) and the reductant (magnesium). The feasibility of tantalum reduction using Dy²⁺ ions dissolved in molten salt has also been demonstrated by utilizing molten salt containing DyCl₂ as a reaction mediator. The mechanism of magnesiothermic reduction of TaCl₅ in the molten salt is discussed using isothermal chemical potential diagrams.     

COLOURING OF PURE IRON AFTER Ti~＋-O~＋ DUAL ION IMPLANTATION

用电化学的方法对经Ｔｉ~＋－Ｏ~＋二重离子注入后的钝铁表面进行处理，可呈现出深蓝、海蓝、褐、紫、金黄、淡黄等颜色用Ｘ射线光电子能谱（ＸＰＳ）对着色表面进行分析，发现表层有ＴｉＯ＿２富集，证明存在钛的氧化物是着色的必要条件．同时着色后的表面存在Ｔｉ的浓化层，着色的深浅程度与钛的浓度有关     

Electron microscope studies of nano-domain structures in Ru-based magneto-superconductors: RuSr(2)Gd(1.5)Ce(0.5)Cu(2)O(10-delta) (Ru-1222) and RuSr(2)GdCu(2)O(8) (Ru-1212)

Microstructures of the RuSr(2)Gd(1.5)Ce(0.5)Cu(2)O(10-delta) (Ru-1222) and RuSr(2)GdCu(2)O(8) (Ru-1212) magneto-superconductors have been investigated by using selected-area electron diffraction, convergent-beam electron diffraction, dark-field electron microscopy and high-resolution electron microscopy at room temperature. Both Ru-1212 and Ru-1222 consist of nm-size domains stacked along the [Formula: see text] direction, where the domains are formed by two types of superstructures due to ordering of rotated RuO(6) octahedra about the c-axis. In Ru-1212, both primitive-and body-centered tetragonal superstructures (the possible space groups: P4/mbm and I4/mcm) are derived to form the corresponding nm-domains. It is of great interest that Ru-1212 consists of domains of two crystallographically different superstructures, while the similar domains observed in Ru-1222 have crystallographically identical superstructure with an orthorhombic symmetry (possible space group: Aeam), related by 90 degrees rotation around the c-axis (Yokosawa et al., 2003, submitted for publication).     

Cementation of Sands Due to Microbiologically-Induced Carbonate Precipitation

In this study, microbial precipitation of carbonate was observed using high microbial urease activity, and it was found that the ratio of Mg/Ca affected the types of crystals produced. Without Mg²⁺, calcite was produced using only CaCl₂, while the presence of Mg produced Mg-calcite, magnesite and/or possibly dolomite of round, spherical or fibrous shapes, depending on reaction time, pH and Mg/Ca ratio. The carbonate produced contributed to the development of cementation for sands. The presence of Mg showed a relatively strong cementation of the carbonate.     

On the aggregation problem in input-output models

The purpose of this paper is to shed new light on the consistent aggregation problem in input-output systems by making use of some properties ofM-matrices. For example, we show that the stability of a multisectoral dynamic multiplier model is invariant under consistent aggregation, that a consistently aggregated dynamic Leontief model is relatively stable if the original system is stable, and that Gillen and Guccione's Third Proposition can be generalized to cover the case of weighted aggregation.     

Imaging of selective nuclear receptor modulator-induced conformational changes in the nuclear receptor to allow interaction with coactivator and corepressor proteins in living cells

Selective nuclear receptor modulators (SNRMs), which are used clinically for the treatment of NR-related diseases, display mixed agonistic/antagonistic activity in a tissue-selective manner depending on the cellular concentrations of coregulator proteins, that is, coactivators and corepressors. The molecular details of the SNRM function provided us with an idea for a rational method for the high-throughput screening of SNRMs in real time in intact living cells. We have developed genetically encoded fluorescent indicators based on the principle of ligand-induced coactivator and/or corepressor recruitment to NR ligand binding domain in single living cells. We demonstrated that an SNRM induces a distinct conformational change in the NR LBD, which is different from that induced by a full agonist or antagonist, but favorable for the recruitment of a coactivator or corepressor protein to the NR. The molecular details of an SNRM binding to a NR, and the subsequently induced conformational changes and recruitment of coregulator protein(s) are important features for the understanding of SNRM action in the living body. Our fluorescent indicators are capable of distinguishing among agonists, antagonists, and SNRMs, and can therefore serve as versatile molecular sensors that predict the pharmacological character of ligands, which is important for an accurate cure of a disease.