Controlled degradation of polystyrene

For the purpose of efficient utilization of waste polystyrene, the recovery method of a styrene oligomer having a molecular weight of 1000–3000 was studied. Thermal and catalytic degradations were carried out. It was impossible to obtain a styrene oligomer with a molecular weight less than 5000 by thermal degradation in the temperature range of 300–500°C. Catalytic degradation in the presence of silica–alumina catalyst in the temperature range of 190–230°C made it possible to control the decrease in molecular weight and to obtain a styrene oligomer having a molecular weight of 500–3000. Simultaneously, the molecular structures of the reaction products from thermal and catalytic degradations were determined by NMR analysis.     

Experimental validation of steering torque feedback simulator through vehicle running test

This paper describes a force feedback system based on real-time multibody dynamic analysis. This system can provide the analyzed reactive force to the operator through the operational device. In this study, this system is used as a steering torque feedback simulator of an automobile. This simulator can provide the haptic sensation of the steering wheel to the operator. For the purpose of evaluating the validity of the developed simulator, we conducted some vehicle running tests with an experimental electric vehicle. The results of these tests were compared with the results simulated on the steering torque feedback simulator. It was shown that the developed simulator can provide a suitable steering torque to the operator. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Dr. Taichi Shiiba received a Doctor of Engineering from The University of Tokyo in 2001. He became an Associate Professor at Meiji University in 2007. A Member of JSME and JSAE, his major areas are multibody dynamics, vehicle dynamics, and driving simulators. Wataru Murata received a B.S. degree in mechanical engineering from Meiji University in 2007. His research interests are vehicle dynamics, real-time analysis, and multibody dynamics.     

Behavior and mechanisms of Ni/ScSZ cermet anode deterioration by trace tar in wood gas in a solid oxide fuel cell

In order to determine both the criterion for diagnosing the deterioration of Ni/ScSZ cermet anodes in solid oxide fuel cells (SOFCs) by tar contaminants in wood gas and the tolerance limit of tar in wood gas for such anodes, the influence of tar concentration in wood gas on anode deterioration behavior was examined by means of scanning electron microscopy. We found that the anode degradation mechanism consisted of three phenomena: the disappearance of Ni particles, the destruction of sintered ScSZ, and carbon deposition. Furthermore, the Ni particle disappearance occurred at lower tar concentrations than did sintered ScSZ destruction and apparent carbon deposition. Therefore, we propose that the disappearance of Ni particles be set as the criterion for confirming deterioration of Ni/ScSZ cermet anodes in SOFCs by tar. On the basis of this criterion, the tolerance limit of toluene in fuel gas was determined to be 3 g/Nm³ when the operating temperature, steam to carbon molar ratio, and current density were 1073 K, 1, and 0.5 A/cm², respectively. The tolerance limit for tar for the fuel cell constructed herein was one to two orders of magnitude higher than that for internal combustion engines.     

Remodelling of capillary networks around muscle fibres in the extensor digitorum longus muscle of the normal aged rat

Structural changes of capillaries around muscle fibres following their degeneration and regeneration were further examined in the extensor digitorum longus muscle of the 24-month-old normal rat. Bundles of muscle fibres were divided into three types: muscle bundles consisting of large muscle fibres exclusively more than 35 microm in diameter (type 1), various-sized muscle fibres ranging from 10 to 60 microm in diameter (type 2) and only small muscle fibres 20-40 microm in diameter (type 3). The mean number of capillaries around a muscle fibre was extremely high in the type 3 muscle bundle (4.83) and much lower in the type 2 muscle bundle (2.72) compared with that in the type 1 muscle bundle (3.48). Capillaries in the type 1 muscle bundle were round or oval in shape and were of the continuous type. In the type 2 muscle bundle, capillaries around large degenerating muscle fibres showed an irregularly compressed shape and the scaffolds of basal laminae were often found around them, being a result of the destruction of capillaries. On the other hand, small-sized capillaries less than 5 microm in diameter, being possibly regenerating capillaries, were found around small (probably regenerating) muscle fibres and often had a small number (less than 10) of fenestrae. Capillaries in the type 3 muscle bundle, similar in shape and size to those in the type 1, frequently branched or joined, but some of them were partially destroyed. These findings suggest that capillaries degenerate and regenerate to remodel capillary networks around the muscle fibres following their degeneration and regeneration, and that to effectively supply oxygen and nutrients to regenerating muscle fibres, capillaries temporarily form fenestrae and then the capillary networks become dense by sprouts from the existing capillaries, but excess capillaries may be gradually destroyed following maturation of the muscle fibres.     

Discontinuous capillary segments in the extensor digitorum longus muscle of aged BUF/Mna rats

We examined the structural changes of capillaries in the extensor digitorum longus muscle of aged (25 months) male BUF/Mna rats, which caused severe muscle weakness of hind legs during aging. The aged muscle mostly consisted of bundles of muscle fibres 15-35 microm in diameter (type 1). In some small areas, however, muscle bundles contained small muscle fibres mainly 15-25 microm in diameter (type 2), possibly indicating that these small fibres are in the course of regeneration after necrosis. Examination of serial ultrathin sections revealed some remarkable changes of capillaries in the type 2 muscle bundle. In some capillaries, the vascular lumen became discontinuous by several close contacts of opposed endothelial cells in their course, forming plural closed vascular segments. Moreover, a solitary endothelial cell was often observed within a scaffold of basal lamina, which remained after destruction of endothelial cells. The segmentation of capillaries and the occurrence of the scaffolds of basal laminae are considered to indicate the degenerative process of capillaries. In some instances, on the other hand, endothelial cells closely apposed each other with no vascular lumen for distances of up to 100 microm, and some capillaries had a narrow vascular lumen (1-3 microm diameter) for a long distance (approximately 300 microm), probably indicating that these structures are in the course of regenerating capillaries to remodel the capillary networks around the muscle fibres. Pericytic processes circularly arranged outside the endothelium at the slit-like and narrow vascular lumen, like hoops, possibly preventing the rupture of the newly-formed vascular lumen from the increased blood flow and/or blood pressure. In addition, the occasional occurrence of capillaries with fenestrations may participate to increase the supply of nutrients and oxygen to the regenerating muscle fibres. The present findings suggest that the capillary networks in the extensor digitorum longus muscle of aged BUF/Mna rats are remodelled following the regeneration of muscle fibres after necrosis, and that on occasion, neighbouring endothelial cells may closely contact with each other both in the degenerative and regenerative processes of capillaries.     

Studies of the crystallisation of gallium hydroxide precipitated from hydrochloric acid solutions by various alkalis

Gallium hydroxide precipitated from aqueous gallium chloride solution on addition of alkalis at varying pH have been aged in the mother liquors for different periods of time. The resulting precipitates have been examined by X-ray diffraction and i.r. spectrophotometry. It is found that the precipitate, separated immediately from the mother liquor after preparation, exists in an amorphous type and transforms to α-gallium oxyhydroxide during aging independent of pH.     

Thermodynamic assessment of the Cu−Pt system

A CALPHAD assessment of the Cu−Pt system has been carried out. Two and four sublattice models were applied to describe the Gibbs free energies of ordered phases where the contribution of SRO is taken explicity into account through the reciprocal parameters. The disordered fcc A1 and liquid phases were treated as substitutional solutions. A consistent set of parameters for the phases in the Cu−Pt system as obtained, and those parameters can satisfactorily reproduce the experimental phase equilibria and thermodynamic properties, such as enthalpies, activity of Cu, and long-range order parameters. This paper was presented at the International Symposium on User Aspects of Phase Diagrams. Materials Solutions Conference and Exposition, Columbus, Ohio, 18–20 October, 2004.     

Mechanical and thermal properties of potassium salts of poly(ethylene‐co‐ethylacrylate): Polyolefin ionomers in the absence of acid groups

The thermal and mechanical properties of ionomers prepared by partial saponification of poly(ethylene‐co‐ethylacrylate) (EEA) with potassium were investigated by using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The Vicat softening temperature (VST) and bending modulus were also evaluated. Molecular design of the present EEA‐based ionomers eliminates acid groups, which affect ionic aggregates for conventional ionomers. The DSC results showed that the melting enthalpy and main crystallization temperature decreased as the ion content increased, whereas on the other hand, the crystal melting temperature at about 360 K did not depend on the ion content, and a secondary exothermal peak was observed in the cooling process. The variance of the VST increased as the crystallinity decreased. The temperature‐dependent curves of DMA data of the EEA‐based potassium ionomers with a higher ion content showed elastic plateau even at temperatures above their crystal melting points. Our results indicate the existence of strong cross‐linking mediated by ion aggregates. The quadratic increase of stiffness as a function of ion content, increasing VST with decreasing crystallinity, and elastic plateau of temperature‐dependent moduli above crystal melting temperature are significant characteristics of the EEA‐based potassium ionomers, which contain ionic aggregations without acid group presence. POLYM. ENG. SCI., 55:1843–1848, 2015. © 2014 Society of Plastics Engineers     

Protein-Protein Recognition Involved in the Intermodular Transacylation Reaction in Modular Polyketide Synthase in the Biosynthesis of Vicenistatin

The ketosynthase (KS) domain is a core domain found in modular polyketide synthases (PKSs). To maintain the polyketide biosynthetic fidelity, the KS domain must only accept an acyl group from the acyl carrier protein (ACP) domain of the immediate upstream module even when they are separated into different polypeptides. Although it was reported that both the docking domain-based interactions and KS-ACP compatibility are important for the interpolypeptide transacylation reaction in 6-deoxyerythronolide B synthase, it is not clear whether these findings are broadly applied to other modular PKSs. Herein, we describe the importance of protein-protein recognition in the intermodular transacylation between VinP1 module 3 and VinP2 module 4 in vicenistatin biosynthesis. We compared the transacylation activity and crosslinking efficiency of VinP2 KS₄ against the cognate VinP1 ACP₃ with the noncognate one. As a result, it appeared that VinP2 KS₄ distinguishes the cognate ACP₃ from other ACPs.     

Quantitative Analysis of The High-Yield Hydrolysis of Kelp by Laminarinase and Alginate Lyase

Kelp is an abundant, farmable biomass-containing laminarin and alginate as major polysaccharides, providing an excellent model substrate to study their deconstruction by simple enzyme mixtures. Our previous study showed strong reactivity of the glycoside hydrolase family 55 during hydrolysis of purified laminarin, raising the question of its reactivity with intact kelp. In this study, we determined that a combination of a single glycoside hydrolase family 55 β-1,3-exoglucanase with a broad-specificity alginate lyase from the polysaccharide lyase family 18 gives efficient hydrolysis of untreated kelp to a mixture of simple sugars, that is, glucose, gentiobiose, mannitol-end glucose, and mannuronic and guluronic acids and their soluble oligomers. Quantitative assignments from nanostructure initiator mass spectrometry (NIMS) and 2D HSQC NMR spectroscopy and analysis of the reaction time-course are provided. The data suggest that binary combinations of enzymes targeted to the unique polysaccharide composition of marine biomass are sufficient to deconstruct kelp into soluble sugars for microbial fermentation.