MASS TRANSFER IN GAS-SPARGED POROUS ELECTRODES

The electrochemical limiting current method was used to measure mass transfer coefficients with cocurrent upward gas-liquid flow in packed bed electrodes. Liquid-solid and overall gas-solid coefficients were determined from limiting current data in the presence of inert or reactive gas flows with the use of a plug flow model. The presence of inert gas flow increased mass transfer coefficients over those in single-phase flow by a factor of up to 1.7. As a result of boundary layer penetration by gas bubbles, sparging with reactive gas increased mass transfer rates by a factor of up to 3.5.     

A novel trans-4-hydroxycinnamic acid derivative from Meyer lemon (Citrus meyeri)

Isolation and structural elucidation of a new trans-4-hydroxycinnamic acid derivative from Meyer lemon (Citrus meyeri hort. ex Y. Tanaka) was carried out. The derivative exhibited the antioxidative activity by ORAC (oxygen radical absorbance capacity) assay and was found in the flavedo and alvedo of Meyer lemon peel.     

用有限元多晶体弹塑性模型预测FCC金属冲压变形后的织构和塑性各向异性

开发出一套适于FCC(面心立方)金属的三维弹塑性有限元程序FEPM-3DFCC，该程序将与应变速率无关的多晶体弹塑性模型引入到立方体单元晶粒塑性应变增量的计算中．文中以Al板为例用FEPM-3DFCC程序计算出常温下单向拉伸和压缩、双向压缩、平面应变、面内剪切和厚向剪切等六种典型受力状态下的织构演变和各向异性变化，并对Al圆管扭曲与拉伸复合加载和Al圆管冷径缩挤拔加工进行了数值模拟．     

Nanoscale dynamic wetting and spreading of molten Ti alloy on 6H–SiC

We have investigated nanoscale features at the reactive wetting front of the molten Ag–27.4 wt.% Cu–4.9 wt.% Ti on 6H–SiC using video movies recorded in situ on a high-temperature stage of a high-resolution transmission electron microscope and also proposed a model of a chemical reaction at each tip. One of the features of reactive wetting and spreading at 1073 K in 4 × 10⁻⁵ Pa was the discontinuous motion of the tip, and the halting time depended on the thickness of an amorphous Si–O layer on SiC, which can be explained by the time needed for the decomposition of the layer by Ti atoms to form TiC nanoparticles since Ti atoms in the molten alloy sufficiently rapidly diffuse to the tip on the SiC surface. Molten Ti and TiC nanolayers preceded the Ti₅Si₃ nanolayer at the tip. The reaction required to form the TiC nanolayer is also the rate-determining step for spreading. The contact angle of the tip increased up to 60–80° when the tip halted, whereas the tip decreased down to 10° on the nonbasal plane and 20° on the basal plane of SiC when it traveled rapidly. The high traveling angle of the molten tip on the basal polar plane of SiC indicates a high interfacial energy between Ti and SiC(0 0 0 1).     

PHASEOLIN RFLP IN BEAN (PHASEOLUS VULGARIS) CULTIVARS

A 0.5 kbp phaseolin gene fragment was used as a probe to study phaseolin restriction fragment length polymorphism (RFLP) in P. vulgaris cultivars. Results obtained from plants displaying type S and type T phaseolin suggest a genomic organization more variable than that previously described. This variability could be exploited to aid gene identification as well as to improve germ plasm bank organization. The same probe was useful in detecting phaseolin linked RFLP in other leguminosae.     

HYDRODYNAMIC CHROMATOGRAPHY: THREE DIMENSIONAL LAMINAR DISPERSION IN RECTANGULAR CONDUITS WITH TRANSVERSE FLOW

Experimental observations^1,9 indicate much poorer separations than are predicted by two dimensional theory. The purpose of this work is to explain these differences and suggest ways in which system performance can be improved.

The large effect of span-wise variation in axial velocity caused by side walls on hydrodynamic separations carried out in rectangular conduits with transverse flow is studied theoretically. As the aspect ratio increases, the steady stale retentivity (convection coefficient) approaches an asymptotic value obtained by neglecting side wall effects. However, the dispersion coefficient does not reduce to that for a flow with no side walls. Indeed, the asymptotic steady state dispersion coefficient is at least six times larger than that obtained by two dimensional theory which neglects side wall effects. As the transverse Peclet number increases, the effect of side walls on the dispersion coefficient becomes much larger.

The present three dimensional theoretical predictions, in contrast to two dimensional ones, are in good agreement with the experimental data of Caldwell, et al.⁹ and Kesner, et al.¹ on electrical field flow fractionation. The results indicate that side wall effects may be of major importance in hydrodynamic chromatography even when the aspect ratio is 70 or more.

The adverse effect of side walls may be avoided by having the membranes enclose thin annular regions rather than rectangular conduits. This should improve performance significantly.     

Development of a food frequency questionnaire to estimate habitual dietary intake in Japanese children

Background  

Food frequency questionnaires (FFQ) are used for epidemiological studies. Because of the wide variations in dietary habits within different populations, a FFQ must be developed to suit the specific group. To date, no FFQ has been developed for Japanese children. In this study, we developed a FFQ to assess the regular dietary intake of Japanese children. The FFQ included questions regarding both individual food items and mixed dishes.     

Chimeric Mice with Humanized Livers: A Unique Tool for in Vivo and in Vitro Enzyme Induction Studies

We performed in vivo and in vitro studies to determine the induction of human cytochrome P450 (CYP) using chimeric mice with humanized liver (PXB-mice^®) and human hepatocytes isolated from the PXB-mice (PXB-cells), which were derived from the same donor. For the in vivo study, PXB-mice were injected with 3-methylcholanthrene (3-MC, 2 or 20 mg/kg) or rifampicin (0.1 or 10 mg/kg) for four days. For the in vitro study, PXB-cells were incubated with 3-MC (10, 50, or 250 ng/mL) or with rifampicin (5 or 25 μg/mL). The CYP1A1 and 1A2, and CYP3A4 mRNA expression levels increased significantly in the PXB-mouse livers with 20 mg/kg of 3-MC (C_max, 12.2 ng/mL), and 10 mg/kg rifampicin (C_max, 6.9 μg/mL), respectively. The CYP1A1 mRNA expression level increased significantly in PXB-cells with 250 ng/mL of 3-MC, indicating lower sensitivity than in vivo. The CYP1A2 and CYP3A4 mRNA expression levels increased significantly with 50 ng/mL of 3-MC, and 5 μg/mL of rifampicin, respectively, which indicated that the sensitivities were similar between in vivo and in vitro studies. In conclusion, PXB-mice and PXB-cells provide a robust model as an intermediate between in vivo and in vitro human metabolic enzyme induction studies.     

2020s scenario analysis of nutrient load in the Mekong River Basin using a distributed hydrological model

A distributed hydrological model, YHyM, was integrated with the export coefficient concept and applied to simulate the nutrient load in the Mekong River Basin. In the validation period (1992–1999), Nash–Sutcliffe efficiency was 76.4% for discharge, 65.9% for total nitrogen, and 45.3% for total phosphorus at Khong Chiam. Using the model, scenario analysis was then performed for the 2020s taking into account major anthropogenic factors: climate change, population, land cover, fertilizer use, and industrial waste water. The results show that the load at Kompong Cham in 2020s is 6.3 × 10⁴ tN a^− 1 (+ 13.0% compared to 1990s) and 4.3 × 10³ tP a^− 1 (+ 24.7%). Overall, the noticeable nutrient sources are cropland in the middle region and urban load in the lower region. The installation of waste water treatment plants in urban areas possibly cut 60.6%N and 19.9%P of the estimated increase in the case without any treatment.     

Percolation threshold for electrical resistivity of Ag-nanoparticle/titania composite thin films fabricated using molecular precursor method

To find the percolation threshold for the electrical resistivity of metallic Ag-nanoparticle/titania composite thin films, Ag-NP/titania composite thin films, with different volumetric fractions of silver (0.26 ≤ φ_Ag ≤ 0.68) to titania, were fabricated on a quartz glass substrate at 600 °C using the molecular precursor method. Respective precursor solutions for Ag-nanoparticles and titania were prepared from Ag salt and a titanium complex. The resistivity of the films was of the order of 10⁻² to 10⁻⁵ Ω cm with film thicknesses in the range 100–260 nm. The percolation threshold was identified at a φ_Ag value of 0.30. The lowest electrical resistivity of 10⁻⁵ Ω cm at 25 °C was recorded for the composite with the Ag fraction, φ_Ag, of 0.55. X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), and transmission electron microscopic (TEM) evaluation of the effect of the morphology and the nanostructures of the Ag nanoparticles in the composite thin films on the electrical resistivity of the film revealed that the films consist of rutile, anatase, and metallic Ag nanoparticles homogeneously distributed in the titania matrix. It could be deduced that the electrical resistivity of the thin films formed at 600 °C was unaffected by the anatase/rutile content within the thin film, whereas the shape, size, and separation distance of the Ag nanoparticles strongly influenced the electrical resistivity of the Ag-nanoparticle/titania composite thin films.