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991.
Nakazawa Takashi; Kawai Hikaru; Okamoto Yuko; Fukugita Masataka 《Protein engineering, design & selection : PEDS》1992,5(6):495-503
A tertiary structure prediction is described using Monte Carlosimulated annealing for the peptide fragment corresponding toresidues 1636 of bovine pancreatic trypsin inhibitor(BPTI). The simulation starts with randomly chosen initial conformationsand is performed without imposing experimental constraints usingenergy functions given for generic interatomic interactions.Out of 20 simulation trials, seven conformations show a sheet-likestructuretwo strands connected by a turnalthoughthis sheet-like structure is not as rigid as that observed innative BPTI. It is also shown that these conformations are mostlylooped and exhibit a native- like right-handed twist. Unlikethe case with the C-peptide of RNase A, no conspicuous -helicalstructure is found in any of the final conformations obtainedin the simulation. However, the lowest-energy conformation doesnot resemble exactly the native structure. This indicates thatthe rigid ß-sheet conformation of native BPTI merelycorresponds to a local minimum of the energy function if thefragment with residues 1636 is isolated from the nativeprotein. A statistical analysis of all 20 final conformationssuggests that the tendency for the peptide segments to formextended ß-strands is strong for those with residues1824, and moderate for those with residues 3035.The segment of residues 2529 does not tend to form anydefinite structure. In native BPTI, the former segments areinvolved in the ß-sheet and the latter in the turn.A folding scenario is also speculated from this analysis. 相似文献
992.
Coating of titanium carbide films on stainless steel by chemical vapour deposition and their corrosion behaviour in a Br2-O2-Ar atmosphere 总被引:1,自引:0,他引:1
Takashi Goto Chen -Yan Guo Hajime Takeya Toshio Hirai 《Journal of Materials Science》1992,27(1):233-239
Stainless steel (SUS304) plates were coated with TiC films using chemical vapour deposition (CVD) as a candidate material for UT-3 which is a promising process of hydrogen production through the thermal decomposition of water. The corrosion behaviour of the TiC film-coated SUS304 plates was examined in a Br2-O2-Ar atmosphere. The effects of CVD conditions on the surface texture, deposition rates and preferred orientation of the TiC films were investigated, and the optimum CVD conditions determined. Corrosion of the TiC film-coated SUS304 plates in the Br2-O2-Ar atmosphere was mainly caused by oxidation of the TiC film and SUS304 substrate. Microcracks in the TiC films lead to corrosion of the SUS304 substrate. At oxygen partial pressures below 0.1 kPa, weight loss was observed due to the formation of volatile titanium and iron bromides. At oxygen partial pressures greater 0.1 kPa, the time dependence of weight increase was parabolic due to the formation of oxide scale. The oxide scales were mixtures of TiO2, Fe2O3 and Fe3O4. The corrosion mechanism is discussed thermodynamically. 相似文献
993.
Dr. Purnandhu Bose Dr. Toshiaki Takei Dr. Xianglan Li Dr. Takashi Minowa Rajamani Rajmohan Dr. Pothiappan Vairaprakash Dr. Kentaro Tashiro 《Chembiochem : a European journal of chemical biology》2018,19(16):1706-1710
A short metal–organic complex array (MOCA) containing a sequence of RPtRRu ( 1Cl ) was found to exhibit unique responses to a major biothiol, glutathione (GSH). Upon binding of GSH to 1Cl , the resultant 1:1 complex ( 1GS ) formed nanofibrous assemblies that suggested supramolecular polymerization through the double‐salt‐bridge structure formation. The binding behavior of this MOCA sequence to calf thymus DNA was also dependent on GSH; a larger conformational change of DNA was observed upon binding with 1GS , relative to that with 1Cl . 相似文献
994.
Peipei Zhu Meijun Yang Qingfang Xu Qingyun Sun Rong Tu Jun Li Song Zhang Qizhong Li Lianmeng Zhang Takashi Goto Ji Shi Haiwen Li Hitoshi Ohmori Marina Kosinova Bikramjit Basu 《Journal of the American Ceramic Society》2018,101(9):3850-3856
Epitaxial 3C–SiC films have been deposited on Si(111) and Si(001) substrates via laser CVD with deposition rate of 12.32 and 15.56 μm/h, respectively. The activation energy of 3C–SiC on Si(111) and Si(001) was 80 and 160 kJ/mol, and the root mean square (RMS) roughness (w) as a function of the film thickness (h) follows power laws of w~h0.31 and w~h0.06, respectively. The growth mechanisms of epitaxial 3C–SiC films on Si(111) and Si(001) was investigated based on the structural analysis and roughness evolution. 相似文献
995.
Fumio Kawamura Hitoshi Yusa Takashi Taniguchi 《Journal of the American Ceramic Society》2018,101(2):949-956
Hexagonal tungsten nitrides were synthesized by the metathesis reaction between WCl6 and NaN3 under high pressure and temperature. As well as tungsten mononitride (WN), which is isostructural with hexagonal tungsten carbide (WC), a nitrogen‐rich hexagonal compound was also confirmed in the product. The ratio of nitrogen to tungsten was determined to be 1.34 by the quantitative combustion method. The composition was estimated to be W2.25N3 by considering the crystal structure that is best explained by the X‐ray diffraction profile. Volume compression measurements under hydrostatic pressure revealed that the WC‐type WN has a higher bulk modulus (K0 = 342 ± 1 GPa) than that of hexagonal W2.25N3 (K0 = 291 ± 2 GPa). 相似文献
996.
Indene Compounds Synthetically Derived from Vitamin D Have Selective Antibacterial Action on Helicobacter pylori
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Kiyofumi Wanibuchi Kouichi Hosoda Masato Ihara Kentaro Tajiri Yuki Sakai Hisashi Masui Takashi Takahashi Yoshikazu Hirai Hirofumi Shimomura 《Lipids》2018,53(4):393-401
Helicobacter pylori infects the human stomach and is closely linked with the development of gastric cancer. When detected, this pathogen can be eradicated from the human stomach using wide‐spectrum antibiotics. However, year by year, H. pylori strains resistant to the antibacterial action of antibiotics have been increasing. The development of new antibacterial substances effective against drug‐resistant H. pylori is urgently required. Our group has recently identified extremely selective bactericidal effects against H. pylori in (1R,3aR,7aR)‐1‐[(1R)‐1,5‐dimethylhexyl]octahydro‐7a‐methyl‐4H‐inden‐4‐one (VDP1) (otherwise known as Grundmann's ketone), an indene compound derived from the decomposition of vitamin D3 and proposed the antibacterial mechanism whereby VDP1 induces the bacteriolysis by interacting at least with PtdEtn (dimyristoyl‐phosphatidylethanolamine [di‐14:0 PtdEtn]) retaining two 14:0 fatty acids of the membrane lipid constituents. In this study, we synthesized new indene compounds ((1R,3aR,7aR)‐1‐((2R,E)‐5,6‐dimethylhept‐3‐en‐2‐yl)‐7a‐methyloctahydro‐4H‐inden‐4‐one [VD2‐1], (1R,3aR,7aR)‐1‐((S)‐1‐hydroxypropan‐2‐yl)‐7a‐methyloctahydro‐1H‐inden‐4‐ol [VD2‐2], and (1R,3aR,7aR)‐7a‐methyl‐1‐((R)‐6‐methylheptan‐2‐yl)octahydro‐1H‐inden‐4‐ol [VD3‐1]) using either vitamin D2 or vitamin D3 as materials. VD2‐1 and VD3‐1 selectively disrupted the di‐14:0 PtdEtn vesicles without destructing the vesicles of PtdEtn (dipalmitoyl‐phosphatidylethanolamine) retaining two 16:0 fatty acids. In contrast, VD2‐2, an indene compound lacking an alkyl group, had no influence on the structural stability of both PtdEtn vesicles. In addition, VD2‐1 and VD3‐1 exerted extremely selective bactericidal action against H. pylori without affecting the viability of commonplace bacteria. Meanwhile, VD2‐2 almost forfeited the bactericidal effects on H. pylori. These results suggest that the alkyl group of the indene compounds has a crucial conformation to interact with di‐14:0 PtdEtn of H. pylori membrane lipid constituents whereby the bacteriolysis is ultimately induced. 相似文献
997.
Thermal properties of glass fiber reinforced polyamide 6 composites throughout the direct long‐fiber reinforced thermoplastic process
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Thomas Whitfield Takashi Kuboki Jeffrey Wood Vanja Ugresic Shyam Sathyanarayana Koffi Dagnon 《Polymer Engineering and Science》2018,58(1):46-54
The direct long‐fiber reinforced thermoplastic (D‐LFT) process offers a streamlined material processing technique and decreases the degradation of the material. To ensure product consistency and process optimization, it is imperative to understand how the process sequence affects degradation and thermal properties of the material during the D‐LFT process. This study investigates variation in molecular weight and thermal properties of the glass fiber reinforced polyamide 6 (PA6) composites throughout the D‐LFT process. Viscosity number (VN) measurements, thermogravimetric analyses (TGA), and differential scanning calorimetry (DSC) analyses were performed on samples taken from different locations along the D‐LFT process. It was found that VN, which is a measure of molecular weight of the PA6 base resin, decreased throughout the processes. In contrast, TGA results suggested that apparent activation energy for decomposition increased during consecutive process stages. Non‐isothermal DSC results showed that there were no significant changes to the degree of crystallization; however, isothermal DSC results indicated that later stages of the process showed a decrease in crystallization half‐time, and the largest changes were observed in areas after the two extrusion portions of the process. POLYM. ENG. SCI., 58:46–54, 2018. © 2017 Society of Plastics Engineers 相似文献
998.
Taisuke Tomonaga Hiroto Izumi Yukiko Yoshiura Toshihiko Myojo Takako Oyabu Byeong-Woo Lee Takami Okada Takashi Marui Ke-Yong Wang Masaru Kubo Manabu Shimada Shingo Noguchi Chinatsu Nishida Kazuhiro Yatera Yasuo Morimoto 《Particle and fibre toxicology》2018,15(1):41
Background
In order to examine whether myeloperoxidase (MPO) can be a useful marker for evaluating the pulmonary toxicity of nanomaterials, we analyzed MPO protein in bronchoalveolar lavage fluid (BALF) samples obtained from previous examinations of a rat model. In those examinations we performed intratracheal instillation exposures (dose: 0.2–1.0 mg) and inhalation exposures (exposure concentration: 0.32–10.4 mg/m3) using 9 and 4 nanomaterials with different toxicities, respectively. Based on those previous studies, we set Nickel oxide nanoparticles (NiO), cerium dioxide nanoparticles (CeO2), multi wall carbon nanotubes with short or long length (MWCNT (S) and MWCNT (L)), and single wall carbon nanotube (SWCNT) as chemicals with high toxicity; and titanium dioxide nanoparticles (TiO2 (P90) and TiO2 (Rutile)), zinc oxide nanoparticles (ZnO), and toner with external additives including nanoparticles as chemicals with low toxicity. We measured the concentration of MPO in BALF samples from rats from 3 days to 6 months following a single intratracheal instillation, and from 3 days to 3 months after the end of inhalation exposure.Results
Intratracheal instillation of high toxicity NiO, CeO2, MWCNT (S), MWCNT (L), and SWCNT persistently increased the concentration of MPO, and inhalation of NiO and CeO2 increased the MPO in BALF. By contrast, intratracheal instillation of low toxicity TiO2 (P90), TiO2 (Rutile), ZnO, and toner increased the concentration of MPO in BALF only transiently, and inhalation of TiO2 (Rutile) and ZnO induced almost no increase of the MPO. The concentration of MPO correlated with the number of total cells and neutrophils, the concentration of chemokines for neutrophils (cytokine-induced neutrophil chemoattractant (CINC)-1 and heme oxygenase (HO)-1), and the activity of released lactate dehydrogenase (LDH) in BALF. The results from the receiver operating characteristics (ROC) for the toxicity of chemicals by the concentration of MPO proteins in the intratracheal instillation and inhalation exposures showed that the largest areas under the curves (AUC) s in both examinations occurred at 1 month after exposure.Conclusion
These data suggest that MPO can be a useful biomarker for the ranking of the pulmonary toxicity of nanomaterials, especially at 1 month after exposure, in both intratracheal instillation and inhalation exposure.999.
The rapid, world‐wide spread of automobiles has necessitated the development of improved technologies for environmental protection,
resource utilization and customer satisfaction. As the designs of automotive components have changed, emphasis has shifted
to tribological approaches. New tribo‐materials are needed for automotive components that must run at higher temperatures
and higher [pressure] x.[velocity] conditions. This paper outlines current issues related to tribo‐materials in passenger
cars.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
1000.
The friction and transfer of various semi-crystalline polymers were studied in several experiments. The cylindrical surfaces of polymers were slid over glass plates at low speed and under constant load. The kinetic friction of PTFE in repeated traverses did not vary with the number of traverses and the transfer of PTFE occurred successively on previously transferred PTFE films. The film transferred at each traverse was extremely thin (< 50 Å). The friction of PTFE decreased with increased humidity in the environment and appeared to be independent of crystalline transitions. Other polymers exhibited higher friction than PTFE and their transfer was generally as small lumps or short streaks. HDPE displayed a very low friction, although the friction of ultrahigh molecular weight polyethylene (UHDPE) was somewhat higher than that of HDPE. With HDPE and UHDPE, as well as with PTFE, long films stretched from one side of the abrasion grooves produced on the polymer frictional surfaces to the other side, like a bridge. The static friction of the three different polymers was very sensitive to the direction of prerubbing on the frictional surfaces and the static friction in sliding parallel to the pre-rubbing direction was much smaller than that perpendicular to it. The roles of the molecular profile and of the banded or spherulitic structure of the polymers in the polymer transfer mechanism are discussed on the basis of the experimental results obtained. 相似文献