Co-Cr系相平衡的热力学计算和fcc相的磁性诱导相分离

Two-phase equilibria between the ferromagnetic fcc and the paramagnetic fcc phase from 800 ℃ to 900 ℃ in the Co-rich region have been detected by the diffusion couple technique. Two phase separation region of the fcc has been confirmed along the Curie temperature. The phase equilibria including the present results and the thermodynamic data of the Co-Cr system reported in the literature were analyzed on the basis of the thermodynamic evaluation. A set of thermodynarnic values for the liquid, fcc, hcp, bcc, sigma phases was obtained. The calculated phase equilibria were in good agreement with most of the experimental data.     

Co-Al二元系中的fcc/hcp马氏体相变和形状记忆效应

It is known that pure Co undergoes martensitic transformation from γ phase (fcc) to ε phase (hcp) by the movement of a/6<112> Shockley partial dislocations at around 400 ℃, however, there have been few systematic works on the SM effect in Co and Co-based alloys. In this study, the fcc/hcp martensitic transformation and the SM effect were investigated in Co-Al binary alloys(mole fraction of Al=0～16%).The γ/ε martensitic transformation temperatures were found from the DSC measurements to decrease with increasing Al content, while the transformation temperature hystereses were observed to increase from 60 ℃ at x(Al)=0 to 150 ℃at x(Al)= 16%. The SM effect evaluated by a conventional bending test was enhanced by the addition of Al over 4%(mole fraction) and Co-Al alloys containing over 10%(mole fraction) exhibit a good SM effect associated with the hcp →fcc reverse transformation above 200 ℃. The SM effect was significantly improved by precipitation ofβ (B2) phase and the maximal shape recovery strain of 2. 2% was obtained, which can be explained by precipitation hardening. The crystallographic orientations between theβ, ε and γ phases were also determined. Finally, the magnetic properties were investigated and it was found that the Curie temperature and saturation magnetization of Co-14% Al(mole fraction) are 690 ℃and 120 emu/g, respectively. It is concluded that the Co-Al alloys hold promise as new high-temperature and ferromagnetic SM alloys.     

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.