Newly identified Chinese hamster ovary cell mutants are defective in biogenesis of peroxisomal membrane vesicles (Peroxisomal ghosts), representing a novel complementation group in mammals

We isolated peroxisome biogenesis-defective mutants from Chinese hamster ovary cells by the 9-(1'-pyrene)nonanol/ultraviolet (P9OH/UV) method. Seven cell mutants, ZP116, ZP119, ZP160, ZP161, ZP162, ZP164, and ZP165, of 11 P9OH/UV-resistant cell clones showed cytosolic localization of catalase, a peroxisomal matrix enzyme, apparently indicating a defect of peroxisome biogenesis. By transfection of PEX cDNAs and cell fusion analysis, mutants ZP119 and ZP165 were found to belong to a novel complementation group (CG), distinct from earlier mutants. CG analysis by cell fusion with fibroblasts from patients with peroxisome biogenesis disorders such as Zellweger syndrome indicated that ZP119 and ZP165 were in the same CG as the most recently identified human CG-J. The peroxisomal matrix proteins examined, including PTS1 proteins as well as a PTS2 protein, 3-ketoacyl-CoA thiolase, were also found in the cytosol in ZP119 and ZP165. Furthermore, these mutants showed typical peroxisome assembly-defective phenotype such as severe loss of resistance to 12-(1'-pyrene)dodecanoic acid/UV treatment. Most strikingly, peroxisomal reminiscent vesicular structures, so-called peroxisomal ghosts noted in all CGs of earlier Chinese hamster ovary cell mutants as well as in eight CGs of patients' fibroblasts, were not discernible in ZP119 and ZP165, despite normal synthesis of peroxisomal membrane proteins. Accordingly, ZP119 and ZP165 are the first cell mutants defective in import of both soluble and membrane proteins, representing the 14th peroxisome-deficient CG in mammals, including humans.     

汽车发动机用无Co排气阀座圈材料的开发

烧结合金广泛地用于制作汽车发动机阀座圈（VSI）。就增高耐热与耐磨耗性能而言，在合金化设计上，烧结合金远比常规的锻钢与铸造合金灵活。特别足，一些高钻烧结材料由于耐磨耗与耐热性高而广泛用作排气阀座圈材料。鉴于近来将发动机的A／F比（空气／燃料比）调整到比常规的贫化（即空气／燃料比增高），排气阀座圈的工作环境趋于严酷。这种A／F比贫化的趋向旨在减少排出的废气和减低燃料消耗。另一方面。也需要不断地减少使用像钴之类环境负荷高的材料。同时，钴昂贵，减低钴含母有利于节省这些材料。这篇论文详细报道了无钴、无铅及有利于环境的排气阀座矧的开发与使用。     

Computer-aided design of surface modified adsorbent for adsorption of 5-hydroxy-methyl-furfural

The saccharide containing in high-starch crops could be converted into various products such as 5-hydroxy-methyl-furfural (HMF) which could be used to manufacture plastics. Currently, most of plastics are produced from petroleum feedstock that is one of the main sources of greenhouse gases. Therefore, the use of HMF produced from high-starch crops might reduce the generation of greenhouse gases since the high-starch crops is renewable. For example, d-fructose derived from high-starch crops could be decomposed into HMF in concentrated hydrochloric acid solution. The HMF could be effectively recovered by phenyl groups surface modified silica gel (PMSG) adsorbent during the decomposition process. However, the optimum loading of phenyl groups on the silica gel surface of PMSG would rely on time-consuming experimental works. Therefore, this research focuses on using Molecular Mechanics Simulator based on frontier orbital theory to obtain the optimum loading of phenyl groups on the silica gel in order to reach the maximum adsorption capacity of HMF. The simulated optimum loading of phenyl groups on the silica surface was about 0.5 mequiv./g. This dosage was in consistent with the value obtained from the experimental tests.     

Concept of secondary heterogeneous structure of long-chain branched polyethylene

The mechanism of formation of surface roughness and extrusion swelling of the extrudate and the steady-shear viscous flow behavior in the region of high shear rate for branched polymers were investigated using two low-density polyethylenes and their sheared samples. These two polyethylenes varied in their degree of branching, molecular weight, and molecular weight distribution but were similar in their melt flow index. The effect of molecular parameters, especially long-chain branching, on viscoelastic properties in the molten state was also considered. Samples of various degree of shearing level were prepared by passing them repeatedly through an extruder. Results of intrinsic viscometry, gel permeation chromatography, and infrared spectroscopy of the original and the sheared samples indicate that no appreciable variation between them takes place in the molecular parameters during the process of extrusion shearing. Both surface roughness and extrusion swelling of the extrudate diminish with increase in the extent of shear. The extrusion shearing affects the surface roughness and extrusion swelling of the extrudate as well as the capillary entrance effect more markedly for the highly branched polymers with considerably higher molecular weight than for the less branched species with bell-type molecular weight distribution. These results demonstrate that heterogeneity becomes more conspicuous with the degree of long-chain branching level, and therefore the role of long-chain branching in the development of the heterogeneity is particularly important. It is suggested that the secondary heterogeneous structure arises through phase separation or from the heterogeneous formation of strongly entangled network at the branching point of the long-chain branching in the manufacturing process of the low-density polyethylene and that its presence causes the distinctive viscoelastic properties of long-chain branched polymer melts.     

Flow properties of molten ethylene–vinyl acetate copolymer and melt fracture

In an investigation of the behavior and formation mechanism of melt fracture the flow properties of molten ethylene–vinyl acetate (EVA) copolymer in the region of high shear rate were measured with a capillary-type rheometer. EVA copolymer differs slightly in flow curve from low-density polyethylene (LDPE); it seems, however, that the difference is due to the difference in molecular weight distribution (MWD) rather than to the materials themselves. The fluidity of molten EVA copolymer having a narrow MWD is equivalent to that of LDPE having a broad MWD and, generally, EVA copolymer has a higher fluidity than LDPE. It is expected that the fluidity increases with incorporation of vinyl acetate at the same MWD and the same M?_w. The critical shear rate increases with melt index and temperature. It cannot be found that the materials themselves and the MWD directly influence the critical point of melt fracture formation when the melt index is taken as a parameter. The critical viscosity (η_c) at which melt fracture forms decreases in an almost straight line with an increase of melt index. It was found from the studies of end correction and behavior of melt fracture formation that melt fracture occurs at the inlet of the die, and it is supposed that the melt fracture formation is caused by the elastic turbulence in the flow pattern due to a failure of recoverable shear strain at the die inlet.     

STM-induced light emission from thin films of perylene derivatives on the HOPG and Au substrates

We have investigated the emission properties of N,N'-diheptyl-3,4,9,10-perylenetetracarboxylic diimide thin films by the tunneling-electron-induced light emission technique. A fluorescence peak with vibronic progressions with large Stokes shifts was observed on both highly ordered pyrolytic graphite (HOPG) and Au substrates, indicating that the emission was derived from the isolated-molecule-like film condition with sufficient π-π interaction of the perylene rings of perylenetetracarboxylic diimide molecules. The upconversion emission mechanism of the tunneling-electron-induced emission was discussed in terms of inelastic tunneling including multiexcitation processes. The wavelength-selective enhanced emission due to a localized tip-induced surface plasmon on the Au substrate was also obtained.     

Influence of shearing history on the rheological properties and processability of branched polymers. IV. Capillary flow and die swell of low-density polyethylene

Low-density polyethylene (LDPE) melts show anomalous rheological behavior; their viscoelastic properties vary with their shearing histories although their molecular structural parameters do not change. Capillary flow and die swell behavior were dependent not only on the experimental conditions such as temperature or shear stress but also on the processing index (PI), which was introduced in a preceding article in order to quantify the anomalous rheological behavior of LDPE melts. In addition, it was found that the flow activation energy at constant shear stress also varied with the shearing histories. The experimental findings are discussed in terms of the rheological flow units of LDPE melts.     

Plastic optical fibre with improved transmittance

A low-loss plastic optical fibre has been manufactured employing polystyrene as core material. The minimum transmission loss was 140 dB/km at 670 nm, and intrinsic material loss of polystyrene was estimated to be 105 dB/km.