Thermodynamic assessment of the Ni-Sb binary system

The Ni-Sb binary alloy system was thermodynamically assessed using CALPHAD approach in this article.Excess Gibbs energies of solution phases,liquid and fcc phases,were formulated using the Redlich-Kister expression.The intermediate phases were modeled by the sublattice model with (Ni,Va)0.5(Ni,Sb)0.25(Ni)0.25 for Ni3Sb_HT phase and (Ni,Va)0.3333(Sb)0.3333(Ni,Va)0.3333 for NiSb phase.The other phases including Ni3Sb,Ni7Sb3,and NiSb2 were treated as stoichiometric compound owing to their narrow composition ranges.Based on the reported thermodynamic properties and phase diagram data,the thermodynamic parameters of these phases were optimized,and the obtained values can reproduce the available experimental data well.     

Synthesis of a minute SiC product from polyvinylsilane with radiation curing: Part II—Ceramization process of radiation cured polyvinylsilane

We have synthesized minute SiC products from polyvinylsilane (PVS), which is a liquid organosilicon polymer, with radiation curing. Since there is a close relationship between the properties of obtained SiC products and pyrolysis condition, it is important to investigate the ceramization process of cured PVS in order to find out the optimum pyrolysis condition. In this paper, the ceramization process of the PVS cured by γ-ray irradiation at room temperature was investigated by gas analysis, thermogravimetric analysis (TGA), density measurement, and so on. It was found that the ceramization of γ-ray cured PVS starts above 500 K, and drastic organic–inorganic conversion occurs in the temperature range of 700–1100 K. According to the changes of mass and density, it was found that the volume shrinkage of PVS during the curing and pyrolysis processes is 80%. The SiC obtained by pyrolysis at 1573 K in argon gas atmosphere showed the density of 2500 kg/m³ and microvickers hardness of 31.6 GPa.     

Development of Bi-base high-temperature Pb-free solders with second-phase dispersion: Thermodynamic calculation, microstructure, and interfacial reaction

Bismuth and its alloys are candidates for Pb-free high-temperature solders that can be substituted for conventional Pb-rich Pb−Sn solders (melting point (mp) = 573 – 583 K). However, inferior properties such as brittleness and weak bonding strength should be improved for practical use. To that end, BiCu−X (X=Sb, Sn, and Zn) Pb-free high-temperature solders are proposed. Miscibility gaps in liquid BiCu−X alloys were surveyed using the thermodynamic database ADAMIS (alloy database for micro-solders), and compositions of the BiCu−X solders were designed on the basis of calculation. In-situ composite solders that consist of a Bi-base matrix with fine intermetallic compound (IMC) particles were produced by gas-atomizing and melt-spinning methods. The interfacial reaction between in-situ composite solders and Cu or Ni substrates was investigated. The IMCs at the interface formed a thin, uniform layer, which is an appropriate morphology for a reliable solder joint.     

Synthesis of a polytitanocarbosilane and its conversion into inorganic compounds

The novel polytitanocarbosilane, formed by the cross-linking of polycarbosilane with titanium tetra-alkoxide, was synthesized to examine the process of converting a multielement organometallic polymer into an inorganic compound. The chemical structure of this polymer was investigated by the techniques of infra-red spectroscopy (IR), gel permeation chromatography (GPC), number average molecular weight measurements and²⁹Si nuclear magnetic resonance (NMR) measurements. The pyrolysis products in N₂ gas at 1400° C and 1700° C were the microcrystalline and crystalline states of silicon carbide and titanium carbide, respectively.     

Phase equilibria in the Cu-Fe-Mo and Cu-Fe-Nb systems

Phase equilibria in the Cu-Fe portion of the Cu-Fe-Mo and the Cu-Fe-Nb systems, in the temperature ranges 1073 to 1573 K and 1373 to 1573 K, respectively, were determined by metallography and scanning electron microscopy-energy dispersive x-ray methods. Based on the present experimental data combined with the previous assessments of the component binary systems, thermodynamic calculations of phase equilibria were carried out adopting the subregular solution model to describe the Gibbs energies of the liquid, bcc, and fcc phases. The evaluated thermodynamic parameters lead to a better fit between calculations and experimental data in both the Cu-Fe-Mo and Cu-Fe-Nb systems.     

Suppression of cell death in primary rat hepatocytes by alpha1-acid glycoprotein

In screening for effective additives for the long-term culture of hepatocytes, the hepatoprotective effect of alpha1-acid glycoprotein (AGP) was observed. AGP prevented primary hepatocytes from undergoing cell death induced by the chemical toxin, bromobenzene. Moreover, AGP added to medium was found to maintain the number of viable hepatocytes for as long as 6 d. The hepatoprotective effect of AGP was lost by removing sialic acid groups at the N-glycan chain terminal of AGP. It is shown that the complete form of N-glycan chain is needed for the hepatoprotectivity of AGP.     

Ln-M-O glasses obtained by rapid quenching using a laser beam

A rapid quenching apparatus employing a laser beam was developed to obtain the glassy state of oxides which have high melting temperatures. Using this apparatus, the glassy state in Ln-Ti-O, Ln-Nb-O and Ln-Ta-O (Ln=lanthanides) systems was investigated. The range of compositions which produced glasses and the crystallization process were studied in detail, and the metastable phases, which appear during the crystallization process, were examined by differential thermal and X-ray diffraction analysis.     

Glucose transporter mediation responsible for morphological changes of human epithelial cells on glucose-displayed surfaces

Cellular morphology is one of the important factors for coordinating cell signaling. In this study, the morphological variation via glucose transporter (GLUT)-mediated anchoring was investigated in the cultures of human mammary epithelial cells in the presence or absence of insulin on culture surfaces with the changed ratios of d- and l-glucose displayed. With increasing ratio of d-glucose displayed on the surfaces, the cells showed a stretched shape in the culture with 10 mug/cm(3) insulin, reaching the highest extent of cell stretching at 100%d-glucose display, whereas round cells were predominant at 0%d-glucose display. In the absence of insulin, on the other hand, the extent of cell stretching showed a concave profile in terms of the ratio of d-glucose displayed, the extent being highest at 50%d-glucose display. Blocking of integrin alpha(5)beta(1) or GLUTs1 and 4 on the cells using corresponding antibodies revealed that the primary mechanism for cell attachment was based on integrin-mediated binding, and that GLUTs1 and 4 contributed largely to morphological changes of cells. Confocal microscopy further revealed that GLUT4 localization occurred in response to d-glucose display as well as insulin addition. In the absence of insulin, GLUT4 spots were extensively observed in the cell body regardless of whether d-glucose was displayed or not. However, in the presence of insulin, the broad distribution of GLUT4 appeared on the basal and apical sides of cells at 100%d-glucose display, in contrast with its localization only on the apical side of cells at 0%d-glucose display. These results suggest that the quantitative balance between GLUTs on the cytoplasmic membrane and d-glucose displayed on a culture surface determines the cell morphology, as explained by the receptor saturation model.     

基于相图和组织控制的先进材料开发

Recent progress on research activities of phase diagrams in our laboratory has been presented. Experimental studies and thermodynamic calculations based on CALPHAD (Calculation of Phase Diagrams) method have been conducted in the following alloy systems. 1. Database on microalloying steels including carbide, nitride and sulfide is now being constructed. 2. ADAMIS (Alloy Database for Micro-Solders) containing 8 elements of Ag, Bi, Cu, In, Sb, Sn, Zn and Pb hasbeen constructed, which can handle all combinations of these elements and all composition ranges. 3. A thermodynamic database of Cu-base alloys including Cu-X binary system and Cu-Fe, Cu-Ni, Cu-Cr base ternarysystems has been constructed. 4. Experimental and thermodynamic calculations on Fe, Ni, Co and Ti aluminides have been conducted. 5. Experimental and thermodynamic calculations on Co base magnetic recording media have been conducted. 6. Thermodynamic analysis of interaction between magnetic and chemical orderings has been performed. By utilizing the information on phase diagrams, the following advanced materials have been developed. (A) New type of high speed steel with high hardness about Hv≈1000 by carbide dispersion carburizing method, (B) New Pb-free machinable stainless steel using titanium carbosulphide. (C) New Pb-free solder for Die-attaching use. (D) Shape memory alloys; Cu-base, Ferromagnetic Ni-base and Fe-base. (E) Invar alloys. (F) Egg-type powder. Typical examples of phase diagrams, phase stability, database and its application for the development of advanced materials will be presented.