Effect of crosslinking structure on sorption of CO2 in photocrosslinked PVCA film

The sorption behavior of CO₂ gas in photocrosslinked poly(vinyl cinnamate) film was examined under atmospheric pressure. The sorption isotherm was well described by the Langmuir equation, suggesting that sorption of CO₂ is mainly governed by adsorption in the microvoids. The amount of sorbed CO₂ was significantly affected by the degree of crosslinking. The CO₂ sorption was enhanced at a lower degree of crosslinking but was decreased at a higher degree of crosslinking. The unexpected increase in the amount of adsorbed CO₂ correlated with the increase in the number of microvoids that occurred as a result of the crosslinking reaction. However, further crosslinking led to a decrease in the mean size of the microvoids. The smaller microvoids, in comparison to CO₂ molecules, did not act as adsorption sites, so that the amount of sorbed CO₂ decreased. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1744–1750, 2000     

Development of advanced arresters for GIS from 66 kV to 500 kV

New zinc oxide elements with a varistor voltage about twice that of conventional ones have been developed by reducing the ZnO grain size with a new additive, making it possible to halve the series number of elements in metal oxide surge arresters. The advanced arresters with these elements for GIS are smaller in volume by 40 to 60% compared with conventional ones. These advanced MOAs increase the flexibility in positioning MOAs and optimizing the GIS layout. This paper describes the performance of the new elements, the specification and construction of the advanced MOAs, and the results of typical evaluation tests. © 2000 Scripta Technica, Electr Eng Jpn, 131(3): 34–42, 2000     

Experiments on bubble behavior in a horizontal narrow divergent passage

This paper investigates a bubble, placed so that it bridges the cross section of a horizontal narrow divergent passage under Earth gravity (1-G). In a narrow passage, inertial forces are known to be small in comparison with viscous forces. Gravitational force is not dominant in bubble behavior in a horizontal narrow passage under the 1-G condition. In this sense, the bubble behavior in the passage is similar to that under a low-gravity condition. Understanding bubble behavior is important in relation to separating a gas from a two-phase gas-liquid flow and controlling a gas-liquid interface under low-gravity conditions. Thus, a single bubble is placed under the 1-G condition. The bubble geometry and its behavior are studied experimentally for gap sizes ranging from 0.5 mm to 2 mm and divergent angles from 1° to 5° using ethyl alcohol as the working fluid. The following results were obtained: (1) the bubble was found to move to the greater cross-sectional area; (2) the gas-liquid interface geometry in a top view can be expressed as a contact circle model that takes the maximum radius in the passage; and (3) the effects of gap size and the projected bubble area on bubble behavior are clarified. © 1998 Scripta Technica, Heat Trans Jpn Res, 27(6): 447–461, 1998     

Lysophosphatic acid modulates prostaglandin secretion in the bovine uterus

Lysophosphatidic acid (LPA) modulates prostaglandin (PG) synthesis via LPA receptor 3 (LPAR3) in the murine endometrium. The lack of functional LPAR3 in mice may lead to embryo mortality. In the present study, we examined the role of LPA in the bovine uterus. We confirmed that LPA is locally produced and released from the bovine endometrium. Moreover, there are enzymes involved in LPA synthesis (phospholipase (PL) D(2) and PLA2G1B) in the bovine endometrium during estrous cycle and early pregnancy. Expression of the receptor for LPA (LPAR1) was positively correlated with the expression of PGE(2) synthase (PGES) and negatively correlated with the expression of PGF(2alpha) synthase (aldose reductase with 20 alpha-hydroxysteroid dehydrogenase activity - PGFS) during early pregnancy. In vivo LPA induced P4 and PGE(2) secretion was inhibited by LPAR1 antagonist (Ki16425). The overall results indicate that LPA is locally produced and released from the bovine endometrium. Moreover, LPAR1 gene expression in the endometrium during the estrous cycle and early pregnancy indicates that LPA may play autocrine and/or paracrine roles in the bovine uterus. LPAR1 gene expression is positively correlated with the expression of the enzyme responsible for luteotropic PGE(2) production (PGES) in endometrium. In cow, LPA stimulates P4 and PGE(2) secretion. Thus, LPA in the bovine reproductive tract may indirectly (via endometrium) or directly support corpus luteum action via the increase of P4 synthesis and the increase of PGE(2)/PGF(2)(alpha) ratio. It suggests that LPA may serve as an important factor in the maintenance of early pregnancy in cow.     

Evaluation of pinhole defect in DLC film prepared by hybrid process of plasma-based ion implantation and deposition

Pinhole defect in diamond-like carbon (DLC) film prepared by a hybrid process of plasma-based ion implantation and deposition using toluene plasma was evaluated by the critical passivation current density in the anodic polarization method. The area ratio of pinhole defects to the SUS304 bare substrate was decreased exponentially with increasing DLC film thickness and reached about 3×10^-6% at film thickness. As a result, it is found that the corrosion resistance of DLC-coated specimens was improved with increasing film thickness. The production of an interfacial mixing layer by ion implantation from methane and acetylene plasmas between the DLC film and the substrate material reduced pinhole defects in the film.     

Specific affinity extraction method for small molecule-binding proteins

Validation of the targets of candidate drugs is critical for rapid and efficient drug discovery and development and for understanding the pharmacological action and potential toxicities of the prospective therapeutic agent. Due to the nonspecific binding of abundant proteins to small molecule-immobilized gels, it is difficult to identify the protein targets of small molecules from crude biological samples by affinity extraction. To address this problem, we have developed an affinity gel for the specific extraction of small molecule-binding proteins. We immobilized small molecules on the agarose gel through a disulfide linker that is cleavable by mild reduction. This system has allowed specific and noncovalent complex formation between the small molecule and the target protein, keeping the effect of the nonspecific abundant proteins adsorbed on both the linker and gel surface to minimum. By preparing this affinity matrix with deoxycholate as a model small molecule, we captured two independent deoxycholate-binding proteins of different affinities from mouse ascites, anti-deoxycholate antibody, and serum albumin. As other proteins were not captured, this affinity extraction method should contribute significantly to the accurate and rapid drug discovery and development.     

Preparation of a single-chain variable fragment and a recombinant antigen-binding fragment against the anti-malarial drugs, artemisinin and artesunate, and their application in an ELISA

Two different recombinant antibodies, a single-chain variable fragment (scFv) and an antigen-binding fragment (Fab), were prepared against artemisinin (AM) and artesunate (AS) and were developed for use in an enzyme-linked immunosorbent assay (ELISA). The recombinant antibodies, which were derived from a single monoclonal antibody against AM and AS (mAb 1C1) prepared by us, were expressed by Escherichia coli cells and their reactivity and specificity were characterized. As a result, to obtain sufficient signal in indirect ELISA, a much greater amount of a first antibody was needed in the use of scFv due to the differences of the secondary antibody and conformational stability. Therefore, we focused on the development of the recombinant Fab antibodies and applied it to indirect competitive ELISA. The specificity of the Fab was similar to that of mAb 1C1 in that it showed specific reactivity toward AM and AS only. The sensitivity of the icELISA (0.16 μg/mL to 40 μg/mL for AM and 8.0 ng/mL to 60 ng/mL for AS) was sufficient for analysis of antimalarial drugs, and its utility for quality control of analysis of Artemisia spp. was validated. The Fab expression and refolding systems provided a good yield of high-quality antibodies. The recombinant antibody against AM and AS provides an essential component of an economically attractive immunoassay and will be useful in other immunochemical applications for the analysis and purification of antimalarial drugs.     

Nitrogen-doped titanium dioxide photocatalysts for visible response prepared by using organic compounds

In order to utilize visible light in photocatalytic reactions, nitrogen atoms were doped in commercially available photocatalytic TiO₂ powders by using an organic compound such as urea and guanidine. Analysis by X-ray photoelectron spectroscopy (XPS) indicated that N atoms were incorporated into two different sites of the bulk phase of TiO₂. A significant shift of the absorption edge to a lower energy and a higher absorption in the visible light region were observed. These N-doped TiO₂ powders exhibited photocatalytic activity for the decomposition of 2-propanol in aqueous solution under visible light irradiation. The photocatalytic activity increased with the decrease of doped N atoms in O site, while decreased with decrease of the other sites. Degradation of photocatalytic activity based on the release of nitrogen atoms was observed for the reaction in the aqueous suspension system.     

High flux mesoporous MCM-48 membranes: Effects of support and synthesis conditions on membrane permeance and quality

This communication reports experimental efforts to synthesize defect-free mesoporous MCM-48 membranes with improved gas flux. We demonstrate a facile and inexpensive method of synthesizing defect-free supported MCM-48 membranes with improved N₂ and CO₂ permeance (>2 × 10⁻⁷ mol/m² s Pa) employing asymmetric supports for the membrane synthesis which contain layers of macropores possessing different pore sizes. The membranes prepared on asymmetric -alumina supports displayed higher gas permeance than those fabricated on symmetric supports (N₂ permeance <10⁻⁷ mol/m² s Pa) as confirmed by unsteady-state gas permeation experiments. Further improvement in gas permeance was achieved by covering one face and the sides of the support with a ceramic tape during membrane synthesis.