Thermodynamics of phosphorus and sulfur in the BaO-MnO flux system between 1573 and 1673 K

The oxidative dephosphorization of carbon-saturated Fe-Mn alloys was successfully demonstrated by measuring the phosphorus partition ratio between BaO-MnO, BaO-MnO-BaF₂, and BaO-CaO_satd.-MnO fluxes and liquid Fe-Mn-C_satd. alloy between 1573 and 1673 K. The phosphorus partition ratio increases with increasing BaO content of the flux. The phosphate capacity of the BaO-MnO flux is as high as that of the BaO-BaF₂ flux and is far larger than those of CaO-bearing fluxes. Addition of BaF₂ to the BaO-MnO flux increases BaO solubility, which increases the phosphate capacity. The manganese partition ratios between the BaO-MnO flux and Fe-Mn-C_satd. alloy were approximately constant at 0.64, 0.33, and 0.23 at 1573, 1623, and 1673 K, respectively. The carbon content of the BaO-MnO flux was measured as functions of slag composition, temperature, and partial pressure of CO. A stable species of carbon in the BaO-MnO flux was found to be BaC₂ experimentally and thermodynamically. The sulfide capacity of the BaO-MnO system at 1573 K has been shown to be far larger than any known flux systems and to be a few times larger than that for the BaO-BaF₂ system. Formerly Graduate Student, Department of Metallurgy, The University of Tokyo     

Insight into unusual impurity absorbability of GeO(2) in GeO(2)∕Ge stacks

Adsorbed species and its diffusion behaviors in GeO(2)∕Ge stacks, which are future alternative metal-oxide-semiconductor (MOS) materials, have been investigated using various physical analyses. We clarified that GeO(2) rapidly absorbs moisture in air just after its exposure. After the absorbed moisture in GeO(2) reaches a certain limit, the GeO(2) starts to absorb some organic molecules, which is accompanied by a structural change in GeO(2) to form a partial carbonate or hydroxide. We also found that the hydrogen distribution in GeO(2) shows intrinsic characteristics, indicative of different diffusion behaviors at the surface and at the GeO(2)∕Ge interface. Because the impurity absorbability of GeO(2) has a great influence on the electrical properties in Ge-MOS devices, these results provide valuable information in realizing high quality GeO(2)∕Ge stacks for the actual use of Ge-MOS technologies.     

Preparation and morphology of transparent poly(methyl methacrylate)–poly(dimethylsiloxane) hybrid materials using multifunctional silicone macromonomer

In this study, transparent poly(methylmethacrylate) (PMMA)‐silicone hybrid materials, P(MMA‐co‐SigUMAx), were prepared with methylmethacrylate (MMA) and multifunctional silicone macromonomer introduced methacryl groups. The transmittance of hybrid materials improved with increase of methacryl groups of silicone macromonomer and reached around 90% T. Atomic force microscopic analysis, scanning electron microscope examinations, and copolymerization kinetics estimation by proton nuclear magnetic resonance revealed that the silicone macromonomer randomly incorporated in the copolymer with MMA by the increase of methacryl groups and suppresses the aggregation of the silicone segment. The hybrid materials introduced over 10 wt % of silicone component had water‐shedding surface and the water contact angle was elevated from 65 to 95°. Though the mechanical properties of hybrid materials were lowered by introduction of flexible silicone component, thermal property such as 5 wt % weight loss temperature were improved. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Water flow experiments and analyses on the cross-flow type mercury target model with the flow guide plates

A mercury target is used in the spallation neutron source driven by a high-intensity proton accelerator. In this study, the effectiveness of the cross-flow type mercury target structure was evaluated experimentally and analytically. Prior to the experiment, the mercury flow field and the temperature distribution in the target container were analyzed assuming a proton beam energy and power of 1.5 GeV and 5 MW, respectively, and the feasibility of the cross-flow type target was evaluated. Then the average water flow velocity field in the target mock-up model, which was fabricated from Plexiglass for a water experiment, was measured at room temperature using the PIV technique. Water flow analyses were conducted and the analytical results were compared with the experimental results. The experimental results showed that the cross-flow could be realized in most of the proton beam path area and the analytical result of the water flow velocity field showed good correspondence to the experimental results in the case when the Reynolds number was more than 4.83×10⁵ at the model inlet. With these results, the effectiveness of the cross-flow type mercury target structure and the present analysis code system was demonstrated.     

Low-Temperature Fabrication of Cordierite Ceramics from Kaolinite and Magnesium Hydroxide Mixtures with Boron Oxide Additions

Thermal reactions of mixtures of ultrafine particles of magnesium hydroxide (Mg(OH)₂) and kaolinite in a composition of MgO:Al₂O₃:2SiO₂ were investigated to obtain dense cordierite ceramics at temperatures <1000°C. While heating the mixture of kaolinite and Mg(OH)₂ with the equivalent of 2 mass% of boron oxide (B₂O₃) (in the form of magnesium borate, 2MgOB₂O₃), an amorphous phase formed at a temperature of ∼850°C after thermal decomposition. Firing the mixture at a temperature of 900°C yielded dense ceramics with an apparent porosity of almost zero. The addition of B₂O₃ promoted the densification at 850°-900°C and accelerated the crystallization of alpha-cordierite. The specimen with 3 mass% of B₂O₃ that was fired at a temperature of 950°C showed a linear thermal expansion coefficient of ∼3 × 10⁻⁶ K⁻¹, a bending strength of >200 MPa, and a relative dielectric constant of 5.5 at 1 MHz. These cordierite ceramics may be used as substrate materials for semiconductor interconnection applications.     

Properties of Modified Lead Zirconate Titanate Ceramics Prepared at Low Temperature (800°C) by Hot Isostatic Pressing

High-density lead zirconate titanate (PZT) ceramics were fabricated for the first time at a temperature as low as 800°C via the hot isostatic pressing (HIP) of a PZT powder with a modified composition of 0.92Pb(Zr_0.53Ti_0.47)O₃—0.05BiFeO₃—0.03Ba(Cu_0.5W_0.5)O₃ that contained 0.5 mass% MnO₂. The resultant PZT ceramics exhibited a microstructure that was denser and finer than that of PZT sintered at 935°C, which is the lowest temperature for the densification of the same composition via normal sintering. The relevant dielectric and piezoelectric properties of the HIPed PZT ceramics were as follows: coefficient of electromechanical coupling ( K ₃₁), 31.8%; mechanical quality factor ( Q _m), 1364; piezoelectric constant ( d ₃₁), −73.7 × 10⁻¹² C/N; relative dielectric constant (ɛ₃₃^T/ɛ₀), 633; dielectric loss factor (tan δ), 0.5%; Curie temperature ( T _c), 285°C; and density (ρ), 8.06 g/cm³. In addition to these reasonably good piezoelectric properties, the HIPed PZT exhibited better mechanical properties—particularly, higher fracture strength—than the normally sintered PZT.     

Fabrication of tin-filled carbon nanofibres by microwave plasma vapour deposition and their in situ heating observation by environmental transmission electron microscopy

Sn-filled carbon nanofibres (CNFs) are fabricated by microwave plasma chemical deposition. Scanning electron microscopy observations revealed the existence of a Sn island under the CNFs. The structure of the CNFs is investigated, and the behaviour of Sn in the internal space of CNFs is revealed by performing in situ heating observations by environmental transmission electron microscopy (ETEM). ETEM observations reveal that they have low-crystallized carbon wall and Sn occupies not only the CNF’s internal space but also its carbon wall. The Sn inside the CNF is completely covered by the carbon wall. Further, the in situ heating observations reveal that Sn within the internal space and the carbon wall of the CNFs diffused to the outside during heating. Moreover, it is found that higher membered carbon rings and defects in the graphite layer act as diffusion routes between disordered carbon layers.     

Dynamic range criterion of THz spectrum for amino acids measurements

Terahertz (THz) absorption spectra have been applied to measure the compositions of amino acid samples.Because the concentration information about a specific composition is involved in its spectrum, keeping the spectrum length and dynamic range as wide as possible is essential for precise measurements.It is well known that a spectrum is always contaminated by apparatus noises.In this paper, we present a criterion for noise cutting based on wavelet transform, which usually extends the range determined by traditional threshold criterion.Finally, theimprovement on measurement precision shows the validity of the new criterion.     

A method for accurate temperature measurement using infrared thermal camera

The temperature distribution on a centre-holed thin foil of molybdenum, used as a sample and heated using a sample-heating holder for electron microscopy, was measured using an infrared thermal camera. The temperature on the heated foil area located near the heating stage of the heating holder is almost equal to the temperature on the heating stage. However, during the measurement of the temperature at the edge of the hole of the foil located farthest from the heating stage, a drop in temperature should be taken into consideration; however, so far, no method has been developed to locally measure the temperature distribution on the heated sample. In this study, a method for the accurate measurement of temperature distribution on heated samples for electron microscopy is discussed.     

A 52-week feeding study of genetically modified soybeans in F344 rats

A chronic feeding study to evaluate the safety of the genetically modified glyphosate-tolerant soybeans (GM soybeans) was conducted using rats. F344 DuCrj rats were fed diet containing GM soybeans or Non-GM soybeans at the concentration of 30% in basal diet. Non-GM soybeans were closely related strain of GM soybeans. These two diets were adjusted to an identical nutrient level. In this study, the influence of GM soybeans on rats was compared with that of the Non-GM soybeans, and furthermore, to assess the effect of soybeans themselves, the groups of rats fed GM and Non-GM soybeans were compared with a group fed commercial diet (CE-2). General conditions were observed daily and body weight and food consumption were recorded. At the intermediate examination (26 weeks), and at the termination (52 weeks), animals were subjected to hematology, serum biochemistry, and pathological examination. There were several differences in animal growth, food intake, serum biochemical parameters and histological findings between the rats fed the GM and/or Non-GM soybeans and the rats fed CE-2. However, body weight and food intake were similar for the rats fed the GM and Non-GM soybeans. Gross necropsy findings, hematological and serum biochemical parameters, organ weights, and pathological findings showed no meaningful difference between rats fed the GM and Non-GM soybeans. These results indicate that long-term intake of GM soybeans at the level of 30% in diet has no apparent adverse effect in rats.