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991.
Kawashima Hitoshi; Yamagishi Jun-ichi; Yamayoshi Michiko; Ohue Mayumi; Fukui Toshikazu; Kotani Hirotada; Yamada Masaaki 《Protein engineering, design & selection : PEDS》1992,5(2):171-176
To identify the sites important for the different biologicalactivities of human interleukin-l (hIL-1), 56 single-amino acid-substitutedmutants of hIL-l were produced in Escherichia coli using site-directedmutagenesis, and were examined for their biological activitiessuch as mouse lymphocyte activating factor activity (LAF activity),cytostatic activity against human melanoma cells A-375 (A375activity) and prostaglandin E2 (PGE2) inducing activity in humanosteosarcoma cells MG-63 (PEI activity). Two amino acid residues,Asp26 and Asp151, were found to be important for these activities.The replacement of Asp26 by Val caused a decrease in LAF andA375 activities by one or two orders of magnitude and a slightdecrease in A375 activity. The Tyr or Phe substitution for Asp151caused decreases in LAF and A375 activities by one or two ordersof magnitude and complete loss of PEI activity. The change fromAsp151 to Lys or Arg resulted in marked decrease in LAF activityand complete loss of A375 and PEI activities. Since Asp26 andAsp151 are close to each other in the three-dimensional structure,the region involving these amino acids seems to be importantfor the biological activities of hIL-1. 相似文献
992.
Jianren Zeng Isao Tanaka Yoshinari Miyamoto Osamu Yamada Koichi Niihara 《Journal of the American Ceramic Society》1992,75(1):195-200
The role of high-purity silica in the fracture of Si3 N4 at high temperatures has been investigated. The flexural strength at 1400°C was found to be greater than that at room temperature. Little plastic deformation was observed even when 10 wt% SiO2 was added and the strain rate was decreased 2 orders of magnitude from that for a standard bend test. Microstructural observations revealed that the glassy phase was localized at intergranular pockets when SiO2 additions were ≤ 10 wt%. High strength at 1400°C despite the presence of a fairly large amount of glassy phase is attributed to a high cavitation threshold in such glassy pockets consisting of high-purity SiO2 . However, the deformation behavior changed abruptly for SiO2 additions of 10 and 20 wt%, which is explained by the morphological change of the glassy phase to thicker intergranular layers which allow macroscopic viscous flow. 相似文献
993.
Initially amorphous and semicrystalline films of poly(ethylene 2,6-naphthalate) with different molecular weights were drawn by two-stage drawing, that is, coextrusion at low temperatures (25–160°C) followed by tensile drawing at high temperatures (200–245°C). Both films could be drawn up to a draw ratio of 8–10 by this method under controlled conditions. The tensile modulus and strength of drawn samples were greatly affected by the draw temperature for the first stage, predrawn morphology, and molecular weight. The remarkable effects of these variables on the tensile properties are closely related to the difference in the resultant amorphous chain orientation of the samples, reflecting the disentanglements and chain slippage during drawing, and the dissipation of chain orientation after processing. 相似文献
994.
Shinji Kishimura Atsumi Yamaguchi Yoshiaki Yamada Hitoshi Nagata 《Polymer Engineering and Science》1992,32(20):1550-1555
We investigated the masking effect, that is, the dissolution inhibition effect, of photoactive compounds (PAC) with various ballast moelcules in novolak-naphthoquinonediazide positive photoresists. Two types of ballast molecules were examined: hydroxybenzophenones (HBP) and several m-cresol novolak resins (MCN) of different molecular lengths. The number of naphthoquinonediazide sulfonic (NQDS) moieties in the resist film and the average esterification value of the PACs were the same for each type of ballast molecule. The smaller the size of the HBP ballast molecule, the larger the masking effect becomes. As the size of the ballast molecule becomes smaller, the number of PACs increases and the degree of dispersion of the NQDS moieties in the resist film increases. At the same time, the longer the MCN ballast molecule, the larger the masking effect becomes. The distance between the NQDS moieties in the MCN ballast molecule is greater than that in the HBP ballast molecule. The masking effect per NQDS moiety in the MCN ballast molecule is larger than that in the HBP ballast molecule. As a result, the distance between the NQDS moieties in the ballast molecule and the degree of dispersion of the NQDS moieties in the resist film control the masking effect, which depends on the probability of existence of NQDS moieties around the alkali-soluble hydroxyl groups of the novolak resin. The molecular length of the ballast molecule influences the degree of entanglement with the novolak resins and promotes the masking effect. 相似文献
995.
Kenji Yamada Naoya Iwamoto Hirokazu Yamane Toshihide Haraguchi Tisato Kajiyama 《应用聚合物科学杂志》2002,86(5):1272-1277
A mixture of a vinyl monomer and a crosslinking agent was photopolymerized to form a crosslinked polymer film. Methacrylate with pendant oligo(oxyethylene) chain and poly(ethylene glycol) dimethacrylate were used as the vinyl monomer and crosslinking agent, respectively. The ionic conductivity of the film increased with an increasing concentration of LiClO4 and then decreased. The size of the quasicrystalline aggregation phase composed of pendant and crosslinking chains in the film decreased with an increasing concentration of LiClO4. The amorphous pendant and crosslinking oxyethylene chains gave rise to increased segmental motion and conductivity. The dissolution was depressed for a decrease in the ionic conductivity at a high LiClO4 concentration at which the interactions among ions became stronger and the crystal phase of LiClO4 was formed. The amount of the dissolution of the aggregation phase increased with an increasing crosslinking agent concentration. The quasicrystalline aggregation phase became larger with an increasing length of the pendant chains, and an increase in the size of the aggregation phase resulted in a decrease in the ionic conductivity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1272–1277, 2002 相似文献
996.
Blend films of silk fibrion (SF) and poly(vinyl alcohol) (PVA), with glycerin as an additive, were made, and the structure and properties of the blends were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FT‐IR) spectroscopy, differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WAXD) and with an Instron Material Tester. The results showed that SF and PVA are principally incompatible and the blends made by the two polymers were phase‐separated. The results, however, also demonstrated that the blend structure could be changed to some extent by addition of 3–8% glycerin. The boundary of the PVA and SF phases became indistinct, as reported by SEM, a new peak appeared in the WAXD curves, the width of the OH absorption peak in the FT‐IR spectra increased, and the melting points changed in the DSC curves. In particular, the mechanical properties obviously increased, from 350 kg/cm2 and 10% of PVA/SF (80/20) film to 832 kg/cm2 and 39% of PVA/SF (80/20) film because of the increase in glycerin. It was suggested that glycerin plays a role in building the relationship between PVA and SF, strengthening the interaction between them and improving their compatibility. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2342–2347, 2002 相似文献
997.
Harumi Homma Satoshi Kubo Tatsuhiko Yamada Yasuyuki Matsushita Yasumitsu Uraki 《木材化学与工艺学杂志》2013,33(4):270-282
Abstract Acetic acid lignin (AL), one of the organosolv lignins, was modified by polyoxyethylation using commercially available polyethylene glycol diglycidylethers (PEGDE) having various chain lengths in order to generate novel nonionic polymeric surfactants. AL could be converted to the amphiphile by modifying with PEGDE (PEGDE-AL) having more than 9 of the ethylene oxide (EO) repeating units. Although the surface activities of PEG and AL were very limited, PEGDE-AL did strongly depress surface tension of water, and showed clear critical micelle concentrations (CMC). The CMC value of PEGDE-AL could be comparable to a commercial anionic lignin surfactant, lignosulfonate. The surface activity of AL amphiphile was further improved by modification with monoepoxides, ethoxy-(2-hydroxy)-propoxy-polyethylene glycol glycidylether (EPEGGE). The surface tension of water was depressed by the addition of the EPEGGE-AL to the same level as Triton® X-100, which is a commercial PEG-based nonionic surfactant, although there is still room for improvement in CMC value. The hydrophile–lipophile balance (HLB) of these AL amphiphiles was in the range of 11–14, and significant biodegradation was observed. These results suggest that the AL amphiphiles can be used as emulsifier and detergent. 相似文献
998.
Hayashida T Ueda M Aiura K Tada H Onizuka M Seno M Yamada H Kitajima M 《Protein engineering, design & selection : PEDS》2005,18(7):321-327
Human pancreatic ribonuclease-1 (RNase1) does not exhibit its cytotoxicity unless it is artificially internalized into the cytosol. Furthermore, once it encounters the cytosolic RNase inhibitor (RI), the activity of RNase1 is seriously reduced. To achieve the cellular targeting of RNase1 and the blocking of RI binding simultaneously, the basic fibroblast growth factor (bFGF) sequence was inserted into RNase1 at the RI binding site using a gene fusion technique. The effect of this fusion protein, CL-RFN89, on the angiogenesis, which was accelerated by FGF-FGF receptor interaction, was investigated. It was shown by using fluorescein-labeled CL-RFN89, that the binding to human umbilical vein endothelial cells (HUVECs) was dependent on the existence of the FGF receptors. In addition, CL-RFN89 inhibited the cellular growth of HUVECs in vitro and also inhibited the tube formation, using a three-dimensional tube formation assay. Furthermore, this fusion protein was shown to prevent in vivo tumor cell-induced angiogenesis, using the mouse dorsal air sac assay. These results demonstrated that CL-RFN89 inhibits angiogenesis in vitro and in vivo and that it can be expected to be a potent antiangiogenic agent. 相似文献
999.
温升是引起微动台精度和环境变化的重要因素,从热特性分析着手进行微动台优化设计是提高微动台性能的一条重要途径。论文提出了一种新型纳米精度六自由度微动台结构,给出了微动台的发热热源、定子线圈等效导热系数和自然对流及强制水冷条件下表面散热系数,建立了微动台三维温度场的数学模型。根据热传导理论,完成了微动台定子线圈稳态温度场的理论计算,并采用数值方法计算了微动台在自然对流和强制水冷条件下的三维温度场分布。根据计算和分析结果,完成了微动台冷却系统的设计。结果表明,采用强制水冷后,微动台动子温升不超过1℃,满足微动台工程设计要求。 相似文献
1000.
Shinji Kudo Taisuke Maki Masahiro Yamada Kazuhiro Mae 《Chemical engineering science》2010,65(1):214-219
A new preparation method of Au/α-Fe2O3 catalyst for CO oxidation reaction was proposed in this paper. The method includes only a simple modification of the conventional coprecipitation method, adding HAuCl4 solution after the growth of iron hydroxide grain to a certain size, but significantly influenced the catalytic activity in the reaction. In the characterization study, XRD (X-ray diffractometer) analysis, TEM (transmission electron microscope) observation, and N2 adsorption measurement showed similar results among the samples calcined at the same temperature, but the effect of the preparation method appeared in the CO adsorption measurement among the samples calcined at 200 °C. Catalysts having high CO adsorption ability also performed well in CO oxidation tests. The CO adsorption and oxidation studies indicated that the proposed preparation method results in stable and effective loading of Au, compared to the conventional coprecipitation method. In the CO oxidation test, the catalyst prepared by the proposed mixing scheme achieved complete CO conversion for more than 3000 h at 25 °C, space velocity 100,000 h?1, and 500 ppm CO. The selectivity for the CO oxidation was confirmed using reformed gas containing excess H2. In addition, the NO reduction reaction was favored over CO oxidation by the catalyst. Thus, we were able to load Au on the α-Fe2O3 effectively and demonstrate its potential as an environmental catalyst. 相似文献