Preparation of monodispersed polymeric microspheres for toner particles by the shirasu porous glass membrane emulsification technique

This investigation describes the experiment directed toward the production of monodispersed toner particles by suspension polymerization. That is, relatively monodispersed poly(styrene-co-divinylbenzene) microspheres containing electrifying additives were successfully prepared by suspension polymerization employing the Shirasu Porous Glass (SPG) membrane emulsification technique. The diameter distribution of the dispersed droplets prepared with an SPG membrane module was fairly narrow, compared with that prepared with a conventional mechanical homogenizer. The effect of Sumiplast Blue S as coloring matter and E-81 as charge control agent on the triboelectric discharging properties of prepared polymeric microspheres was studied. The addition of electrifying additives strongly affected the triboelectric discharging property. It was consequently clarified that a small amount of electrifying additives added raised the electrostatic capacity of polymeric microspheres. However, a further addition reduced the triboelectric discharge of polymeric microspheres. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1107–1113, 1997     

The True Origin of Ductile Fracture in Aluminum Alloys

It has generally been assumed that metals usually fail as a result of microvoid nucleation induced by particle fracture. Here, we concentrate on high-density micropores filled with hydrogen in aluminum, existence of which has been largely overlooked until quite recently. These micropores exhibit premature growth under external loading, thereby inducing ductile fracture, whereas the particle fracture mechanism operates only incidentally. Conclusive evidence of a micropore mechanism is provided by the observation of an instantaneous release of gas at failure. We can therefore conclude that the growth of micropores dominates ductile fracture. Since the material we used has a standard pore density, we can assume that an identical fracture mechanism operates in other aluminum alloys. This finding suggests that intense heat treatment, which is generally believed to enhance the mechanical properties through homogenization, may have entirely the opposite effect. This revelation will have a major impact on the engineering design of metals.     

Structural control of core/shell polystyrene microcapsule‐immobilized microbial cells and their application to polymeric microbioreactors

Polystyrene microcapsules possessing a large single core and highly microporous wall were prepared as immobilization supports for microbial cells by a new method based on phase separation of polystyrene within a mixed organic solvent system in an oil‐in‐water (o/w) emulsion. The structures of core and micropore were controlled by changing the concentration of isooctane in the organic phase and the temperature of solvent evaporation. The immobilization of baker's yeast into the polystyrene microcapsules was carried out by entrapping the yeast into calcium alginate beads before encapsulating in the microcapsules and followed by removing the beads with HCl solution. The morphology of the microcapsules was observed by means of SEM, and the activity of the immobilized yeast was evaluated by using the microcapsules in ethanol fermentation. It was found that the formation of the core and wall pore was remarkably influenced by the isooctane concentration, and the diameter of the core was affected by the temperature of solvent evaporation. The yeast was successfully immobilized into the polystyrene microcapsules at a high density and a high catalyst activity by the proposed immobilization method. Furthermore, the polystyrene microcapsules exhibited a high operational stability in the repeated batchwise fermentation test. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1966–1975, 2003     

Polymer electrolyte membranes derived from novel fluorine-containing poly(arylene ether ketone)s by controlled post-sulfonation

Precise assignment with ¹H, ¹³C and some two dimensional NMR measurements showed that sulfonation reaction by concentrated sulfuric acid at 30 °C of fluorine-containing poly(arylene ether ketone) copolymers derived from 4,4′-bis(2,4,5,6-pentafluorobenzoyl)diphenyl ether (BPDE) and 9,9-bis(4-hydroxypehnyl)fluorene (HF) and 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (6FBA) yielded quantitative introduction of sulfonic groups onto 2- and 7-positions of fluorene ring in HF unit. A series of sulfonated poly(arylene ether ketone)s with different ion exchange capacity was prepared by using this method with different compositions of HF and 6FBA, and membranes obtained from these polymers were characterized by TGA, moisture and water uptake, proton conductivity, methanol permeability, and Fenton testing. These membranes showed sufficient thermal stability, high proton conductivity at high humidified condition for PEFC and good balance in proton conductivity in water and methanol permeability for DMFC. On the other hand, they showed relatively high swelling by water probably due to weak intermolecular interaction caused by the existence of fluorine atoms in the polymer structure.     

Autoimmune pancreatitis: CT and MR characteristics

OBJECTIVE: Our goal was to elucidate the CT and MR imaging characteristics in patients with autoimmune pancreatitis, which is a reversible chronic pancreatitis with an autoimmune cause. CONCLUSION: On CT and MR imaging, a capsulelike rim, which is thought to correspond to an inflammatory process involving peripancreatic tissues, appears to be a characteristic finding of autoimmune pancreatitis. Also, diffuse pancreatic enlargement along with hypointensity on T1-weighted MR images and delayed enhancement on dynamic CT and MR studies are other features of this disorder.     

β to ω phase transformation due to aging in a Ti–Mo alloy deformed in impact compression

We investigated the roles of vacancies and their clusters introduced in a Ti–20mass% Mo alloy by high-speed compression in the formation of aged ω-phase crystals. Specimens were deformed by a static compression mode and a high-speed compression mode, and were then aged. The relationships between morphology of aged ω-phase crystals and deformation modes are discussed along with the roles of vacancies and their clusters in the nucleation and growth of aged ω-phase crystals. Aged ω-phase crystals were found to be smaller but of higher density in a high-speed deformation specimen. These results suggest that vacancies and their clusters easily become nucleation sites of aged ω-phase crystals. Several aged ω-phase crystals in a high-speed deformation specimen were of string-like shape. High-resolution electron microscopy confirmed that the string-like crystals have the ω-phase crystal structure. One of the roles of vacancies of and their clusters introduced by high-speed deformation is considered to be relief of compressive stress, which is predicted to arise in the course of transformation.     

Electrooptical‐responsive microsphere with ferroelectric liquid crystalline segments

We synthesized a ferroelectric liquid crystalline monomer (4‐[4′‐(7‐octeneloxy)benzoyloxy]benzoate‐2‐methylbutyester, OBBM) possessing both carboxyl p‐benzolxybenzoate and carboxyl (s)‐(‐)‐2‐methylbutylester as a mesogenic group in its side chain. The liquid crystalline and styrene monomers were employed to make matrices of microspheres prepared by dispersion, suspension, or emulsion polymerization. In this study, we investigated, in detail, physicochemical properties, thermal responses, and electrooptical responses of the microspheres possessing liquid crystalline abilities. The ferroelectric liquid crystalline monomer OBBM had a thermotropic liquid crystalline ability, two‐phase transition temperatures, and a Smectic C* texture, which is characteristic of ferroelectric liquid crystalline substances. The microspheres prepared also exhibited a liquid crystalline ability, and the phase‐transition temperatures toward the liquid crystalline segments into the microspheres prepared by copolymerizing the liquid crystalline and styrene monomers could be decreased with increasing of the styrene monomer. Furthermore, we found that the microspheres remarkably exhibited electrooptical responses at about 8 V. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2490–2499, 2001     

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.     

Early HCC and adenomatous hyperplasia: evaluation of arterial and portal blood flow with CTA, CTAP, and pathologic correlation

In order to analyze the hemodynamic properties of early hepatocellular carcinoma (HCC) and adenomatous hyperplasia (AH), three lesions (two HCCs, one AH) depicted as hypoattenuating at CTA and iso attenuating at CTAP were correlated with the histopathological findings. The number of normal hepatic arteries in the tumor was lower than in the liver. Degeneration and narrowing of the lumens were also seen microscopically. All tumors showed the replacing growth pattern and had similar numbers of the portal tracts in the tumor to the liver. The decreased number of intratumoral normal arteries is suspected to be a characteristic finding of the early stage of HCC.     

Reaction of α-tocopherol with alkyl and alkylperoxyl radicals of methyl linoleate

α-Tocopherol was reacted with alkyl and alkylperoxyl radicals at 37°C in bulk phase. The lipid-free radicals were generated by the reaction of methyl linoleate with the free radical initiator, 2,2′-azobis(2,4-dimethylvaleronitrile) (AMVN) under air-insufficient conditions. The products were isolated by high-performance liquid chromatography. Their structures were identified as 2-(α-tocopheroxy)-2,4-dimethylvaleronitrile (1), a mixture of methyl 9-(8a-peroxy-α-tocopherone)-10(E),12(Z)-octadecadienoate and methyl 13-(8a-peroxy-α-tocopherone)-9(Z),11(E)-octadecadienoate (2), methyl 9-(α-tocopheroxy)-10(E),12(Z)-octadecadienoate (3a), methyl 13-(α-tocopheroxy)-9(Z),11(E)-octadecadienoate (3b), α-tocopherol spirodiene dimer (4) and α-tocopherol trimer (5). When methyl linoleate containing α-tocopherol was oxidized with AMVN under airsufficient conditions, the main products were 8a-alkyl-peroxy-α-tocopherones (2). In addition to these compounds, 6-O-alkyl-α-tocopherols (1, 3a and 3b) were formed when the reaction was carried out under air-insufficient conditions. The results indicate that α-tocopherol can react with both alkyl and alkylperoxyl radicals during the autoxidation of polyunsaturated lipids.