Surface hardness and transparency of poly(methyl methacrylate)‐silica coat film derived from perhydropolysilazane

To prepare hard and transparent poly (methyl methacrylate)‐silica coat film on glass or polycarbonate substrates, poly(methyl methacrylate‐co‐2‐hydroxyethyl methacrylate) random copolymers and perhydropolysilazane (PHPS) were blended in solution. Then the solution was cast on the substrates. The grafting of PHPS onto 2‐hydroxyethyl methacrylate unit was analyzed by ¹H NMR spectroscopy. Surface hardness and transparency of the coat film were measured by nano‐indentation method and UV‐Vis spectroscopy, respectively. Surface hardness of coat film depended on the volume fraction of silica in the coat film, and reached 2.7 GPa when the volume fraction of silica was 76.4%. Transparency of the coat films prepared with PHPS was almost 100%, indicating that the coat film prepared with PHPS was highly transparent not only on glass substrate but also on the polycarbonate substrate. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Removal of endocrine disruptors in milk by circulation through polydimethylsiloxane tubing

A simple circulating system was developed, in which an aqueous solution, cow milk, or human milk was circulated through hydrophobic polymeric tubing to remove the endocrine disruptors from the solution by sorption into the tubing. The effect of circulating parameters, such as tube length, circulating time, and flow rate, against the removal ratio (R) of endocrine disruptors was investigated. R of 1,2,3,4,5,6‐hexachlorocyclohexane (γ‐HCH, lindane) increased with the length of the hydrophobic polymeric tubing, circulating time, and flow rate when cow milk containing 1 ppm γ‐HCH was circulated through polydimethylsiloxane tubing. The R values of several endocrine disruptors with different octanol–water distribution coefficients (log P_ow) was investigated for γ‐HCH and dichlorodiphenyltrichloroethane in an aqueous solution, cow milk, and human milk. A similar trend for R versus log P_ow of the human milk to that of the aqueous solution and cow milk was observed. The R values of the endocrine disruptors decreased in the following order: Aqueous solution > Human milk > Cow milk. Stable micelles in cow milk disturbed the shift of the endocrine disruptors from the milk micelles into the hydrophobic tubing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3634–3640, 2006     

TEM image simulation study of small carbon nanotubes and carbon nanowire

Recent findings of extremely small diameter carbon nanotube and nanowire in the core of a multi-walled carbon nanotube (MWCNT) have attracted interests from broad range of researchers. Direct observation of carbon nanotube is usually done using a transmission electron microscope (TEM). When nanotubes become smaller, it becomes harder to correctly understand the TEM images, not only because of the weak scattering, but also due to the artifact that starts to appear because of the interference effect and the inappropriate defocus condition.In this study, we have shown that the artifact such as ghost fringes due to inappropriate defocus conditions of the TEM appear in the core of an MWCNT, and can be misinterpreted as either carbon nanowire or small carbon nanotube. It is also shown that, in the TEM image, it is hard to distinguish a single-walled nanotube bundle from a double-walled carbon nanotube bundle. Finally, we propose that the cross-sectional observation is necessary for the correct characterization of single- and double-walled carbon nanotube bundles.     

Improvements of data quality of the LHD Thomson scattering diagnostics in high-temperature plasma experiments

In Large Helical Device (LHD) experiments, an electron temperature (T(e)) more than 15 keV has been observed by the yttrium-aluminum-garnet (YAG) laser Thomson scattering diagnostic. Since the LHD Thomson scattering system has been optimized for the temperature region, 50?eV≤T(e)≤10?keV, the data quality becomes worse in the higher T(e) region exceeding 10 keV. In order to accurately determine T(e) in the LHD high-T(e) experiments, we tried to increase the laser pulse energy by simultaneously firing three lasers. The technique enables us to decrease the uncertainties in the measured T(e). Another signal accumulation method was also tested. In addition, we estimated the influence of high-energy electrons on T(e) obtained by the LHD Thomson scattering system.     

Fracture Process of Silicon Carbide Fiber-Reinforced Glasses

This paper evaluates the fracture process for fiber-reinforced glasses under tensile loading. Two types of unidirectionally aligned Nicalon SiC-fiber-reinforced glass with different fiber coatings were examined. One channel acoustic emission (AE) measurement was employed during the tensile tests. Probabilistic fracture analysis as well as the replication technique were used to investigate the relation between the AE signals and fracture processes. The AE technique proved to be an effective method for observing fracture processes of the material systems studied. The fracture process could be distinguished in terms of the AE amplitude. AE signals with high amplitudes corresponded to fiber breaking; AE signals with low amplitudes corresponded to matrix cracking, interfacial debonding, and fiber pullout. In the well-toughened material studied the reinforcing fibers would break extensively over 75% load of the ultimate strength.     

Solid-state source of atomic oxygen for low-temperature oxidation processes: application to pulsed laser deposition of TiO2:N films

An atomic oxygen (AO) source has been redesigned to coordinate with a pulsed laser deposition system and used to grow nitrogen-doped TiO(2) films by deposition of TiN and simultaneous irradiation of the substrate with AO. The AO source uses an incandescently heated thin tube of zirconia as an oxygen permeation media to generate pure AO of low kinetic energy. The emission flux is calibrated using a silver-coated quartz crystal microbalance. The thin shape of the probe and transverse emission geometry of this emission device allow the emission area to be positioned close to the substrate surface, enhancing the irradiation flux at the substrate. AO irradiation is crucial for formation of TiO(2) phases via oxidation of the deposited TiN laser plume, and is effective for decrease of the substrate temperature for crystallization of anatase phase to as low as around 200 °C.     

Corrosion behavior of rapidly solidified Mg-Zn-rare earth element alloys in NaCl solution

Rapidly solidified flaky powder metallurgy (RS FP/M) processing was applied for preparation of corrosion-resistant bulk Mg alloys with Zn and rare earth elements. The corrosion behavior of the melt spun Mg-Zn-La and Mg-Zn-Yb alloy ribbons in 1% NaCl solution was investigated in order to determine optimum composition of corrosion-resistant Mg alloys. The effect of heat-treatment on the corrosion behavior of RS Mg-Zn-La and Mg-Zn-Yb alloys also was studied. In the Mg-Zn-La alloys, as-quenched alloys showed good corrosion resistance in the NaCl solution, but heat-treatment led to degradation due to microstructure change, that is, reduction in dispersion of the Mg₁₇La₂-type intermetallic compound. In the Mg-Zn-Yb alloys, both as-quenched and heat-treated Mg_97.5Zn_0.5Yb₂ alloys exhibited low corrosion rates because fine distribution of Mg₂Yb-type intermetallic compound in α-Mg matrix was not largely changed by heat treatment.     

Oxidation Behavior of a Re-Base Diffusion-Barrier/β-NiAl Coating on Nb–5Mo–15W at High Temperatures

A β-NiAl coating with or without a Re-base alloy layer was formed on a Nb–5Mo–15W alloy. The coated alloys were oxidized isothermally in air at 1373 and 1473 K. Electroplating of a high (more than 70at.%)-Re–Ni film, Cr-pack cementation, Ni plating, and then Al-pack cementation, in this sequence, formed a coating structure with Re-base alloy and β-NiAl layers. The Re-base alloy layers were comprised of an outer σ-phase in the Re–Cr(Ni) system and an inner χ-phase in the Re–Nb(Cr) system. It was found that reaction between the β-NiAl and the alloy substrate was significantly suppressed when the Re-base alloy layers were present. The Re-base σ and χ phases were found to be good candidates for a diffusion barrier against inward-Al diffusion because they have very low solubilities for Al.     

制造业的大都市圈——名古屋圈的产业结构与城市结构

泡沫经济崩溃以后，在通货紧缩经济的基础上进行了产业重建和结构重组，也就是企业活动的重新组合。在这个过程中，虽然出现了明显的企业破产、衰退或失业者增加等消极现象，不过这些是向新的经济阶段过渡时必然会有的，基本上已被大众所接受。进入新世纪以来经济景气指数回升，东京圈等大都市圈起到了带头作用，地方的都市圈也跟随而上。然而，虽然同是大都市圈，状况却各不相同。居第二位的大阪圈与第三位的名古屋圈的情形也不一样。如果从地域经济的角度对二者进行比较，名古屋圈出现繁荣的势头而大阪圈停滞不前，结果二者之间的差距有所减小。针对这种状况，近年来很多人从经济发展动向的角度出发对其原因进行探讨。不光在经济界和学术界，传媒和文化界、时尚界等等都对其非常关注。名古屋圈，或者名古屋大都市圈的这种良好的经济态势是本质性的还是暂时性的？它们产生的条件是什么？对这些问题可以从各种不同的角度进行分析，本文拟从产业结构和城市结构的角度出发，探讨名古屋圈和名古屋大都市圈近年来的经济发展。     

Development of sintered Ti-30mass%Mo alloy and its corrosion properties

Ti-30mass%Mo alloy is characterized by far better corrosion resistance than pure titanium in non-oxidizing acid such as 35% HC1 solution. This alloy was newly developed in this work by a powder metallurgical process, because the conventional melting-casting process had difficulties in manufacturing the alloy owing to its heavy gravity segregation. The corrosion behavior of sintered Ti-30Mo alloy was studied by both immersion test and electro-chemical measurement. The corrosion rate of 1.3X10⁻²[mm/yearxxx] was obtained by immersion test in 35% HC1 solution, which was 10³ times superior to that of pure titanium. The potentio-dynamic polarization curve of this alloy in 35% HC1 solution showed more noble corrosion potential and lower anodic current density than those of pure titanium. The passive film formed on the alloy, in which Mo was enriched by preferential dissolution of titanium, thought to suppress the anodic reaction and improve its corrosion resistance.