Thickness dependence of H2 gas sensor in amorphous SnQx films prepared by ion-beam sputtering

Amorphous SnO_x films were deposited by ion-beam sputtering on sintered alumina substrates. Amorphous film sensors were prepared by annealing the films at 300° C for 2 h in air. The thickness dependence of resistivity and hydrogen gas sensitivity were measured at 150° C over the thickness range 1 to 700 nm. A resistivity maximum was observed in ultrathin films. Resistivity increased by three orders of magnitude with increasing film thickness from 0.9 to 7.4 nm and then decreased by five orders of magnitude from 7.4 to 35 nm. Ultrathin film sensors showed sensitivity maxima around a thickness of 10 nm. Sensitivity and resistivity of ultrathin films were significantly influenced by the thermal expansion coefficient and the surface state of the substrate.     

Developmental ability of cloned embryos from neural stem cells

The success rate is generally higher when cloning mice from embryonic stem (ES) cell nuclei than from somatic cell nuclei, suggesting that the embryonic nature or the undifferentiated state of the donor cell increases cloning efficiency. We assessed the developmental ability of cloned embryos derived from cultured neural stem cell (NSC) nuclei and compared the success rate with that of embryos cloned from other donor cells such as differentiated NSCs, cumulus cells, Sertoli cells and ES cells in the mouse. The transfer of two-cell cloned embryos derived from cultured NSC nuclei into surrogate mothers produced five live cloned mice. However, the success rate (0.5%) was higher in embryos cloned from cultured NSC nuclei than from differentiated NSCs (0%), but lower than that obtained by cloning mice from other cell nuclei (2.2-3.5%). Although the in vitro developmental potential to the two-cell stage of the cloned embryos derived from NSC nuclei (73%) was similar to that of the cloned embryos derived from other somatic cell nuclei (e.g., 85% in Sertoli cells and 75% in cumulus cells), the developmental rate to the morula-blastocyst stage was only 7%. This rate is remarkably lower than that produced from other somatic cells (e.g., 50% in Sertoli cells and 54% in cumulus cells). These results indicate that the undifferentiated state of neural cells does not enhance the cloning efficiency in mice and that the arrest point for in vitro development of cloned embryos depends on the donor cell type.     

Control of percolation curve by filler particle shape in Cu- SBR composites

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

成型冶金灰脱硫剂对烟气脱硫及其再生的研究

冶金灰(MD)因含大量的金属氧化物而有很强的脱硫能力.但是,MD颗粒细小,易被气流吹走,不能直接应用.必须将MD成型为有一定尺寸和足够机械强度后才能采用.研究了成型冶金灰脱硫剂(DSMD)的成型、脱硫和再生.实验结果指出,首先将诸如粘土,水玻璃,聚磷酸钠等粘结剂,水和MD混合,混合质量比MD:粘土:水玻璃:聚磷酸钠:水为100:3.3:3.3:3.3:5.0,然后将混合粉末压制成圆柱状块体,最后在973 K时结烧3 h.DsMD在烟气脱硫(FGD)过程中的脱硫率和MD相近,而且经过几次连续的脱硫-再生循环后,脱硫率仍保持稳定.此外,当DSMD未被贯透和DSMD的硫容量到达约5～6 mol/kg(＞773 K)之前,烟气出口处的H2S浓度可保持在小于10 mg/m3的水平.     

Melting Temperatures of Monazite and Xenotime

The melting temperatures of natural and synthetic monazite and xenotime (rare-earth ortnophosphates) were measured, using a heliostat-type solar furnace. The results obtained are as follows: natural monazite from Japan (2057°40°C), synthetic monazite RPO₄ (R=La, 2072°20°C; R=Ce, 2045°20°C; R=Pr, 1938°20°C; R=Nd, 1975°20°C; R=Sm, 1916°20°C), and synthetic xenotime RPO₄(R=Y, 1995°20°C; R=Er, 1896°20°C).     

Fine structure of tooth enamel in the yellowing human teeth: SEM and HRTEM studies

Objective : The aim of this study was to clarify an influence of the fine structure of human tooth enamel to the yellowing teeth. Materials and methods : Sound maxillary first premolars of 15–50‐year‐old females that were extracted for the orthodontic treatment were used as the test samples. The tooth enamel sections of these teeth that prepared by ion polishing were observed by scanning electron microscopy (SEM). Furthermore, the fine structure of substance filling the inter‐rod spaces was analyzed by high resolution transmission electron microscopy (HRTEM). Results : In white tooth, the inter‐rod spaces were observed at the width of about 0.1 μm, while in yellow tooth, the inter‐rod spaces were not clearly observed by SEM. HRTEM observations revealed for the first time that the inter‐rod spaces were filled with fine particles of poorly crystallized hydroxyapatite in the yellow tooth. In yellow tooth, it was considered that the color of the inner dentin was recognized due to the decrease of light scattering by filling the tooth enamel inter‐rod spaces. The generation of particles in the tooth enamel inter‐rod spaces was considered to be caused by the long‐time progression of calcification. Conclusions : These results suggested that the change in fine structure, filling in inter‐rod spaces of tooth enamel, was related to progression of calcification in the inter‐rod spaces with advancing age and one of the factors of yellowness of human tooth. Microsc. Res. Tech. 79:14–22, 2016. © 2015 Wiley Periodicals, Inc.     

Near-infrared imaging of water in a polymer electrolyte membrane during a fuel cell operation

A novel technique of spectroscopic imaging using a near-infrared (NIR) laser sheet beam was developed for visualization of liquid water in a proton-exchange membrane (PEM) sandwiched between two opaque electrodes set in a polymer electrolyte fuel cell (PEFC). In-plane two-dimensional distribution of water in the thin membrane was clearly visualized during the fuel cell operation. Under the condition of fuel feeding into the PEFC without humidification, water was generated by the fuel cell reaction in the whole electrode area. In contrast, under the condition of fuel feeding with humidification, the PEM got wet in the vicinity of a gas flow field locally.