Effect of polyurethane surface chemistry on its lipid sorption behavior

The relationships among surface, bulk properties and lipid sorption behaviors of segmented polyurethanes (SPUs) with various polyol soft segments were investigated. The polyols used in this study were poly(ethylene oxide) (PEO), poly(tetramethylene oxide) (PTMO), and poly(dimethylsiloxane) (PDMS). The hard segment of these segmented polyurethanes was composed of 4,4'-diphenylmethane diisocyanate and 1,4-butanediol, present at 50 wt%. X-ray photoelectron spectroscopic (XPS) and dynamic contact angle measurements were carried out in order to analyze the surface chemical structure in the air- and water-equilibrated states. XPS revealed that in the air-equilibrated state, lower surface free energy components were enriched at the air-solid interface, whereas in the water-equilibrated state, higher surface free energy components were enriched at the water-solid interface. The change in environment from air to water induced the surface reorganization in order to minimize interfacial free energy. Lipid sorption behaviors of SPUs were investigated by means of infrared spectroscopy. Even after extensive rinsing of the surface, the amount of lipid present on the SPU surface was more than that calculated on the assumption that a monolayer covers the SPU surface. Therefore, the lipid was not only adsorbed on the surface of SPU but absorbed into SPU. The SPU with hydrophilic PEO sorbed larger amount of phospholipid compared with that with hydrophobic polyol such as PTMO and PDMS. Also, the competitive sorption behaviors of phospholipid and cholesterol from their mixed liposome solution were studied. The ratio of sorbed cholesterol to phospholipid increased with an increase in surface hydrophobicity owing to the hydrophobic nature of cholesterol.     

Effects of nondensifying inclusions on the densification and microstructure of zinc oxide matrix composites

The densification and microstructure development of ZnO containing Zn₇Sb₂O₁₂, ZrO₂, and aggregated ZnO were investigated to elucidate the effect of nondensifying inclusions on the sintering of ceramic/ceramic composites. The inclusion retarded the densification, and the degree of retardation was found to depend on the chemical species of inclusion; Zn₇Sb₂O₁₂ had the largest effect, followed by ZrO₂ and then aggregated ZnO last. The experimental results for aggregated ZnO was explained by the theory which predicts the generation of backstresses. The backstresses give a less significant effect on the densification. For Zn₇Sb₂O₁₂ and ZrO₂, the microstructure of the matrix varied with distance from an inclusion particle; much porosity was observed in the region surrounding the inclusion. Circumferential voids, which are responsible for the suppression of densification, form during the initial stage of sintering. Inclusion particles generate an anchoring effect which retards the densification of the matrix immediately surrounding the inclusion particle during the intermediate stage.Supported by the Inamori Foundation.     

CSDL: a language for cooperative systems design

The aim of a cooperative system is to coordinate and support group activities. Cooperative Systems Design Language (CSDL) is an experimental language designed to support the development of cooperative systems from specification to implementation. In CSDL, a system is defined as a collection of reusable entities implementing floor control disciplines and shared workspaces. CSDL tries to address the difficulties of integrating different aspects of cooperative systems: cooperation control, communication, and system modularization. This paper presents CSDL as a specification language. Basic units are coordinators that can be combined hierarchically. A coordinator is composed of a specification, a body, and a context. The specification defines the cooperation policy; the body controls the underlying communication channels; and the context defines coordinators' interaction in modular systems     

Dynamic Mechanical Properties and Adhesive Joint Strengths of Emulsion Polymers Produced by Power Feed Technique. III. Adhesive Joint Strengths of Grafted Power Feed Copolymer

Power feed copolymers were synthesized using styrene and n-butyl acrylate through non-uniform feeding emulsion polymerization. Poly(vinyl alcohol) (PVA) was used as a protective colloid, onto which vinyl monomers were grafted. Power feed copolymer had a very broad glass transition temperature compared with random copolymer, even if grafting and/or crosslinking were introduced to the system. This tendency was almost the same as the non-grafted power feed copolymer where only low molecular weight surfactant was used.

Adhesive joint strengths of power feed copolymers were evaluated compared with random copolymers. In the case of usual linear power feed copolymer, the adhesive joint strengths were not higher than those of random copolymer, which was considered to be due to the lower film strengths of the power feed copolymer. Power feed copolymer having grafting showed slightly higher adhesive joint strengths over a wide range of temperatures than random copolymer. When crosslinking was introduced to the system, power feed copolymer showed much higher adhesive joint strengths over a wide temperature range.     

Metastatic Voyage of Ovarian Cancer Cells in Ascites with the Assistance of Various Cellular Components

Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy and has a unique metastatic route using ascites, known as the transcoelomic root. However, studies on ascites and contained cellular components have not yet been sufficiently clarified. In this review, we focus on the significance of accumulating ascites, contained EOC cells in the form of spheroids, and interaction with non-malignant host cells. To become resistant against anoikis, EOC cells form spheroids in ascites, where epithelial-to-mesenchymal transition stimulated by transforming growth factor-β can be a key pathway. As spheroids form, EOC cells are also gaining the ability to attach and invade the peritoneum to induce intraperitoneal metastasis, as well as resistance to conventional chemotherapy. Recently, accumulating evidence suggests that EOC spheroids in ascites are composed of not only cancer cells, but also non-malignant cells existing with higher abundance than EOC cells in ascites, including macrophages, mesothelial cells, and lymphocytes. Moreover, hetero-cellular spheroids are demonstrated to form more aggregated spheroids and have higher adhesion ability for the mesothelial layer. To improve the poor prognosis, we need to elucidate the mechanisms of spheroid formation and interactions with non-malignant cells in ascites that are a unique tumor microenvironment for EOC.     

A novel gene delivery system in plants with calcium alginate micro-beads

We have produced micrometer-sized calcium alginate beads referred to as "bio-beads" that encapsulate plasmid DNA molecules carrying a reporter gene. In order to evaluate the efficiency of the bio-beads in mediating genetic transfection, protoplasts isolated from cultured tobacco cells (BY-2) were transfected with bio-beads containing a plasmid that carries the modified green fluorescent protein gene CaMV35S-sGFP. With the bio-beads treatment, approximately ten-fold higher GFP expression was observed after 24 h incubation compared to that with the conventional method using a naked plasmid solution. Transfection was up to 0.22% efficient. These results indicate that bio-beads have a possibility for efficient transformation in plants.     

Effects of age and sex on sodium chloride sensitivity: association with plasma renin activity

The mechanism by which excessive NaCl intake raises blood pressure has not been fully clarified. The present study was undertaken in 87 Japanese inpatients with essential hypertension to investigate the interrelation among effects of age, sex and the renin-angiotensin system on NaCl sensitivity. After ingesting a regular NaCl diet (170 mmol/day) for one week, subjects were placed sequentially on a week of low NaCl diet (50 mmol/day) and a week of high NaCl diet (340 mmol/day). NaCl sensitivity defined as the difference in mean blood pressure between the low and high NaCl diets did not differ between genders. NaCl sensitivity was positively correlated with age and the change in PRA. The fall in PRA after NaCl loading was significantly smaller in women than in men. By multiple regression analysis, age and the change in PRA independently contributed to the change in mean blood pressure. Furthermore, the interaction between sex and the change in PRA was selected as a statistically significant variable. In conclusion, NaCl sensitivity of blood pressure is independently associated with age and the inadequate suppression of the renin-angiotensin system. Because the contribution of the change in PRA to NaCl sensitivity was greater in women than in men, the mechanism of blood pressure elevation after NaCl loading may differ between genders.     

The occurrence of geometric polyprenol isomers in the rubber-producing plant, Eucommia ulmoides Oliver

The chain length and geometric isomerism of polyprenols from Eucommia ulmoides Oliver were analyzed using supercritical fluid chromatography. After intensive effort to establish separation conditions for geometric isomers, a phenyl-bonded silica gel-packed column was found that cleanly separated poly-trans and-cis prenols. The presence of longchain poly-trans prenols (>9 mers) was confirmed for the first time in plants. Trans isomers were found in the leaf, seed coat, and root, but not in the bark and seed. Poly-trans prenols in this plant may act as intermediates for trans-polyisoprene biosynthesis.