Observation of the electrorheological effect of siliconeoil/polymer particles suspension

A liquid insulator that suspends small particles is one of the electrorheological fluids (ERF) whose apparent viscosity becomes larger under an electric field because of the formation of particle chains. Since many possible applications of ERF are expected, the development of a more practical ERF is required. We have investigated the ER effect of silicone oil in which small particles are suspended. Silica particles, silica particles coated by conductive polymer film, and polymer particles (microcrystalline cellulose), with a diameter between 5~100 μm, are investigated in order to clarify the difference between suspending materials. To measure the ER effect, a rotational viscometer was constructed. It became clear that the shear stress for cellulose particles is much stronger than that for other particles because of its peculiar particle chain formation due to the particle shape     

In Situ Observation of Phase Separation of a Barium Borate Melt in a Stable Immiscibility Region under Microgravity

The precipitation of droplets was directly observed on a BaO–B₂O₃ melt in a drop shaft experiment. This is the first time that precipitation of droplets has been observed in a 4.5 s drop test. The melt film of 4BaOz96B₂O₃ (mol%) held on a platinum wire loop was heated above the critical tem-perature to produce uniformity and was cooled down to the phase separation temperature range. Phase separation of the melt was observed directly with a video camera. The IR image of the melt was simultaneously detected with a CCD array and was converted into a two-dimensional thermograph.     

Cell distributions in and sound absorption characteristics of flexible polyurethane foams

In this article, the two-dimensional distributions of cells from the cross section of some flexible polyurethane foams were cleared, and the three-dimensional distributions of cells based on Saltykov's theory were estimated further. As a result, it was found that a mean of the two-dimensional distributions of cells was a good linear relation with a mean of the three-dimensional distributions of cells, and it was confirmed that cell structure of the foams which should have been analyzed in the three-dimensional distributions was evaluated by analysis of the two-dimensional distributions fully. It was also found that not only cell number but also cell distribution was necessary in the evaluation of flexible polyurethane foams, and cell diameter was closely related to the sound absorption coefficient in polyester-based flexible polyurethane foams. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1395–1402, 1997     

Effect of rolling deformation on the structures and properties of multi‐walled carbon nanotube filled isotactic polypropylene

Isotactic polypropylene filled with various contents of multi‐walled carbon nanotubes (MWCNTs) were fabricated by the injection molding technique and then rolled at room temperature. The unrolled samples (URS) and rolled samples (RS) were characterized by X‐ray diffraction studies, scanning electron microscopy, mechanical and micromechanical tests and differential thermal analyses. Although the URS exhibit the lamellar α‐crystal with a*‐axis orientation, the RS show the same crystals with both a*‐ and c‐axis orientation, which is explained by interlamellar and intralamellar slips and lamellar destruction. Scanning electron micrographs display distinct surface morphological features for both URS and RS. While the tensile strength of RS is higher than that of URS, the Young's modulus (Y) is found to be lower than that of URS. Anisotropy in microharness (H) parallel and perpendicular to the rolled direction has been detected, although H for both samples increases with increasing MWCNT contents. The average relationship H/Y ≈ 0.18 as estimated for URS is closer to the predicted value of 0.10 for polymers than the H/Y ≈ 0.22 obtained for RS. The lamellar thickness for URS increases with increase of MWCNT content and that for RS decreases, as evaluated from both differential thermal analyses and X‐ray diffraction data. Copyright © 2011 Society of Chemical Industry     

Stabilization of Hydroxynitrile Lyases from Two Variants of Passion Fruit,Passiflora edulis Sims and Passiflora edulis Forma flavicarpa,by C-Terminal Truncation

Because the synthesis of chiral compounds generally requires a broad range of substrate specificity and stable enzymes, screening for better enzymes and/or improvement of enzyme properties through molecular approaches is necessary for sustainable industrial development. Herein, the discovery of unique hydroxynitrile lyases (HNLs) from two species of passion fruits, Passiflora edulis forma flavicarpa (yellow passion fruit, PeHNL-Ny) and Passiflora edulis Sims (purple passion fruit, PeHNL-Np), isolated and purified from passion fruit leaves is reported. These are the smallest HNLs (comprising 121 amino acids). Amino acid sequences of both enzymes are 99 % identical; there is a difference of one amino acid in a consensus sequence. PeHNL-Np has an Ala residue at position 107 and is nonglycosylated at Asn105. Because it was confirmed that natural and glycosylated PeHNL-Ny showed superior thermostability, pH stability, and organic tolerance to that of PeHNL-Np, it has been speculated that protein engineering around the only glycosylation site, Asn105, located at the C-terminal region of PeHNL-Ny, might contribute to the stabilization of PeHNL. Therefore, the focus is on improved stability of the nonglycosylated PeHNL by truncating its C-terminal region. The C-terminal-truncated PeHNLΔ₁₀₇ was obtained by truncating 15 amino acids from the C terminus followed by expression in Escherichia coli. PeHNLΔ₁₀₇ expressed in E. coli was not glycosylated, and showed improved thermostability, solvent stability, and reusability similar to that of the wild-type glycosylated form of PeHNL expressed in Pichia pastoris. These data reveal that the lack of the high-flexibility region at the C terminus of PeHNL might be a possible reason for improving the stability of PeHNL.     

Categorical observers for metamerism

A method is proposed to generate categorical colour observer functions (individual colour matching functions) for any field size based on the CIE 2006 system of physiological observer functions. The method combines proposed categorical observer techniques of Sarkar et al with a physiologically-based individual observer model of Asano et al and a clustering technique to produce the optimal set of categorical observers. The number of required categorical observers varies depending on an application with as many as 50 required to predict individual observers' matches when a laser projector is viewed. However, 10 categorical observers are sufficient to represent colour-normal populations for personalized colour imaging. The proposed and recommended categorical observers represent a robust and inclusive technique to examine and quantify observer metamerism in any application of colorimetry.     

Composition Regulation by Flow Copolymerization of Methyl Methacrylate and Glycidyl Methacrylate with Free Radical Method

It is important to match the feeding ratio of comonomers to the composition ratio in the resulting copolymers as closely as possible in industrial production, where the goal is often to produce more a homogeneous composition in copolymers. In this study, a flow copolymerization system with a conventionally initiated free radical method, together with randomly selected polymerization conditions is investigated. It is succeeded in achieving a closer match between the composition ratio and feeding ratio than previously reported in the copolymerization of styrene with methyl methacrylate and of glycidyl methacrylate with methyl methacrylate, which will widen the range of applications, by precisely controlling the mixing and heating in a flow polymerization apparatus. This is confirmed by the fact that the estimated values of reactivity ratios, r₁ and r₂, which are used in the reaction kinetics of copolymerization, are close to 1.     

Microhardness studies of PMMA/natural rubber blends

The microhardness, H, of PMMA/natural rubber blends, prepared following the solution method has been investigated by means of the microindentation technique. Hardness changes are correlated with the variation of the glass transition temperature. The influence of temperature and degree of deformation on H were additionally examined. The inclusion of rubber particles in the PMMA matrix is shown to soften the blends. The variation of the micromechanical property at the phase boundary of polymer/rubber particle has been studied. Results reveal that H drastically drops at the interphase. In the case of the drawn materials, the indentation anisotropy (ΔH) is shown to gradually increase with the draw ratio, where ΔH is found to be higher for the PMMA/rubber blend than for the original PMMA. This result is explained by the higher orientation of the PMMA molecules near the periphery of stretched rubber particles. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 205–210, 2004     

Increased Lipid Synthesis and Decreased β-Oxidation in the Liver of SHR/NDmcr-cp (cp/cp) Rats, an Animal Model of Metabolic Syndrome

SHR/NDmcr-cp (cp/cp) rats (SHR/NDcp) are an animal model of metabolic syndrome. A previous study of ours revealed drastic increases in the mass of palmitic (16:0), oleic (18:1n-9), palmitoleic (16:1n-7), cis-vaccenic (18:1n-7) and 5,8,11-eicosatrienoic acids in the liver of SHR/NDcp. However, detailed information on the class of lipid accumulated and the mechanism responsible for the overproduction of the accumulated lipid in the liver was not obtained. This study aimed to characterize the class of lipid accumulated and to explore the mechanism underlying the lipid accumulation in the liver of SHR/NDcp, in comparison with SHR/NDmcr-cp (+/+) (lean hypertensive littermates of SHR/NDcp) and Wistar Kyoto rats. In the liver of SHR/NDcp, de novo synthesis of fatty acids (16:0, 18:1n-9 and 16:1n-7) and triacylglycerol (TAG) synthesis were up-regulated and fatty acid β-oxidation was down-regulated. These perturbations of lipid metabolism caused fat accumulation in hepatocytes and accumulation of TAG, which were enriched with 16:0, 18:1n-9 and 16:1n-7, in the liver of SHR/NDcp. On the other hand, no changes were found in hepatic contents of diacylglycerol and unesterified fatty acid (FFA); among FFA, there were no differences in the hepatic concentrations of unesterified 16:0 and stearic acid between SHR/NDcp and two other groups of rats. Moreover, little change was brought about in the expression of genes responsive to endoplasmic reticulum stress in the liver of SHR/NDcp. These results may reinforce the pathophysiological role of stearoyl-CoA desaturase 1 and fatty acid elongase 6 in the liver of SHR/NDcp.     

Creation of functional materials by use of a slow crystallization process in the nonequilibrium state. I. porous polyamide microparticles

Recently a number of investigations have focused on the self‐organization process from the nonequilibrium state as a new technique that may be used to develop many functional materials. In many cases, amorphous polymers were used and semicrystalline polymers were seldom used in spite of their importance. In this study, we basically investigated the crystal structure, crystalline process, and inner structures of polyamide by using slow phase separation and crystallization process from the nonequilibrium state of the polymer solution. We were able to observe the crystalline lamella growing twisted from the center of the particle. Between these lamella layers, narrow pores were created. From this investigation, we developed a new method to create functional materials of polyamide, the semicrystalline polymer. Porous spherical particles may be properly applied to functional materials such as adsorption materials, catalyst support materials, and so on. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2428–2432, 2003