Vesicles from sucrose fatty acid esters

It has been confirmed, from observations with an electron microscope after staining negatively with aqueous uranyl acetate solutions and using a flourescent microscope, that sucrose fatty acid esters form closed vesicles. The range of particle size of the vesicle, consisting of chromatographically fractionated sucrose dilaurate, was apparently 70–700 nm in the longer diameter of individual vesicles based on the transmission electron microscopic (TEM) observation. The weight-average particle size was 424 nm as shown by means of the photon-correlation method. The amounts of 6-carboxyfluorescein trapped in the vesicles of sucrose fatty acid esters were determined, and it was ascertained that the volumes of the central water phase depended upon the acyl chain lengths of fatty acid residues. Further, the effect of the additives [cholesterol and dicetyl phosphate (DCP) was examined. As an example, the vesicle of sucrose stearate had a central water phase of 1.7 one water/mol ester, and showed a slow release of 6-carboxyfluorescein from the central water phase after preparation of the vesicle.     

Reduction of irreversible capacities of amorphous carbon materials for lithium ion battery anodes by Li2CO3 addition

Amorphous carbon materials for lithium ion battery anodes which contain a small amount of Li₂CO₃ were prepared by three methods. The obtained materials were characterized using X-ray diffraction (XRD) analysis, Raman spectroscopy and CO₂ adsorption experiments. Although the XRD profiles and Raman spectra of these materials were similar to those of carbon materials synthesized with no addition, the amount of CO₂ adsorbed was largely decreased by Li₂CO₃ addition. These results suggest that the micropores in these materials were plugged and/or filled with Li₂ CO₃. Galvanostatic lithium charging and discharging experiments showed that the irreversible capacity of the material can be significantly decreased by Li₂CO₃ addition, which is thought to be due to the plugging of the pore inlets by Li₂CO₃. Moreover, it was also found that the reversible capacities of the materials can be increased by adjusting both the amount of Li₂CO₃ addition and carbonization temperature.     

Preparation of fine polymer particles containing metallocene derivatives

This article deals with preparations of fine particles of metallocene copolymers by emulsifierfree emulsion polymerization of vinylferrocene (VFc), ferrocenylmethyl methacrylate (FMMA), 1-ferrocenylethyl methacrylate (1-FEMA), 2-ferrocenylethyl methacrylate (2-FEMA), and 1-ruthenocenylethyl methacrylate (1-REMA) with acrylonitrile (AN), styrene (St), and methyl methacrylate (MMA) in water/ethanol medium. As a result, spherical copolymer particles containing metallocene derivatives have been successfully synthesized in the particle size of ca. 120 to 600 nm. The contents of ferrocenyl or ruthenocenyl groups in copolymer particles increased with increasing concentration of charged metallocene derivatives, while the amounts of metallocene derivatives incorporated into particles are much lower than the charged ratio. © 1994 John Wiley & Sons, Inc.     

Desiccation survival of Listeria monocytogenes and other potential foodborne pathogens on stainless steel surfaces is affected by different food soils

Food processing environments are suspected to be the primary source of Listeria monocytogenes contamination of foods. We investigated the survival of L. monocytogenes on stainless steel that was soiled with food components (minced tuna, ground pork, and cabbage) followed by dehydration. Stainless steel coupons were inoculated with 10⁷ CFU/coupon and stored up to 30 days. In comparison with Staphylococcus aureus and Salmonella Typhimurium, L. monocytogenes demonstrated the highest survivability where about 3 log CFU/coupon remained at the end of the experimental period. While survival during the early storage period was markedly affected by both food-component attachment and food type, a long dehydration period diminished the effect of those.     

Environmental ecological modeling of human blood lead levels in East Asia

Environmental ecological modeling (EEM), which unifies models simulating transport of chemicals and exposure of humans to chemicals, was used to simulate long-term trends of female adult human blood lead levels (BLLs) and historical exposure to the atmospheric lead in four East Asian countries: Japan, Korea, China, and Vietnam. Anthropogenic lead emissions to the atmosphere in Vietnam were estimated from energy statistics to be 1931 t yr(-1). Calculated BLLs generally agreed with those observed in samples collected in these countries as the error factors were less than 2. The model results revealed that BLLs decreased significantly in Tokyo (by 58%) and Seoul (by 45%) in recent decades and confirmed the effects of efforts to reduce environmental lead in Japan and Korea. The model results also revealed that BLLs in Beijing did not decrease in this decade as much as in Tokyo and Seoul, despite the phasing out of leaded gasoline, and that the contribution from the atmospheric component was increasing (43% in 2009). Finally, we applied EEM to simulate BLLs of children in Hanoi. The probability of children having BLLs greater than 50 μg L(-1) was 7.5%, which was greater than those observed in developed countries.     

Heat transfer of tubes closely spaced in an in-line bankTransfert thermique de tubes serres dans un reseau en ligneWärmeübergang in einem fluchtenden rohrbündelTeплoпepeнoc oт тpyб в кopидopнoм лyKhcyкe

An experimental investigation of heat transfer around four cylinders closely spaced in a cross-flow of air has been conducted. The cylinders are settled in tandem with equal distances between centers. Their inline pitch ratio is in the range of $\text{1.15 ≤}\text{c}\text{d ≤ 3.4}$ (c = distance between cylinders' centers, d = cylinder diameter); the Reynolds number ranges from 10⁴ to 5 × 10⁴. It is found that there exists a critical Reynolds number Red_c at which the heat transfer behavior changes drastically, and is correlated with the in-line pitch ratio by $\text{Red}{}_{\mathrm{c}}\text{= 1.14 × 10}{}^5\text{(}\text{c}\text{d)}{}^{\mathrm{?5.84}}$.Variations of characteristic features of the mean and local Nusselt numbers are discussed in relation to the length of the vortex formation region behind the cylinder.     

Higher order structures and toughening mechanisms for simultaneously polymerized polymethacrylate/polyurethane

Amorphous polymer/crystalline polymer blends can be prepared via the simultaneous polymerization of polymethacrylate/polyurethane combinations. The relationship between higher order structures and fracture mechanisms in these blends must be uncovered to elucidate the source of the increased fracture toughness of such materials. The present work involves the production of blended polymethacrylate/polyurethane and assess the internal structures of these specimens using optical and electron microscopy. These observations reveal the presence of both spherulites and elastomeric phases. The spherulites consisting of the polyurethane and are several micrometers in diameter whereas the phase-separated polyurethane elastomeric domains are approximately 100 nm in size. Multiple cracks, crack bridging and plastic deformation around the precrack tips of loaded specimens are evidently responsible for the increased toughness of these blends. The former two phenomena are attributed to the presence of spherulites while the plastic deformation of the methacrylate matrix is ascribed to cavitation of the polyurethane elastomeric phases in response to loading.