SiO2-supported NbC catalysts were prepared by using temperature-programmed reactions (TPR). XAFS analysis confirmed that Nb2O5 was reduced to NbO2 in the first TPR stage and converted into NbC in the second TPR stage. Nb particles grew only in the second TPR stage. Formation of highly dispersed NbC particles on SiO2 surfaces was achieved. 相似文献
Oils were extracted from the pits ofCeltis sinensis Pers. var.japonica Nakai and the fruits ofZelkova serrata Makino, of the family Ulmaceae. The oils were examined for their characteristics and fatty acid composition. The percentages
of component acids ofCeltis andZelkova oils determined by gas liquid chromatography of their methyl esters were, respectively: propionic (−, 0.9), butyric (−, trace),
caproic (−, 0.1), caprylic (−, 7.3), capric (−, 76.5), lauric (−, 3.3), myristic (0.1, 1.0), palmitic (6.8, 2.8), hexadecenoic
(trace, −), stearic (3.5, 0.4), oleic (7.5, 3.9), linoleic (80.0, 3.3), linolenic (2.1, 0.5), and arachidic (trace, −) acids. 相似文献
In this study, flexible transparent hybrid films with low thermal expansion coefficient were prepared by combination of alumina fillers and polymerizable/non-polymerizable surface modifiers with carboxyl group. Four types of alumina fillers with different shape and size were used in this study, and could modify with surface modifiers containing carboxyl groups by electrostatic interaction and disperse homogeneously in resulting hybrid films regardless of the shape and size. So the hybrid films obtained showed high transmittance around 90%T, and it was considered, from transmission electron microscopic analysis, alumina fillers were dispersed at near original filler size, without aggregation. Moreover, thermal mechanical analysis cleared that the use of pillar or fiber type filler is more effective to reduce CTE compared with plate type fillers, especially CTE of hybrid film prepared with fiber type filler was drastically decreased to 17 ppm/K, while the influence by the difference of filler shape/size was not observed on tensile properties, surface hardness. By use of fiber type alumina filler and combination of polymerizable surface modifier and non-polymerizable surface modifier which seems to interact with matrix, for optimizing of the crosslink density, it was possible to reduce CTE, while the good mechanical properties was kept. Finally, hybrid film indicating low CTE value as 19 ppm/K, high flexibility (windable against 0.4 mm radius steel bar), and good tensile properties and surface hardness which were equal to or higher than those of matrix could prepared. 相似文献
The interphase transfer behavior of poly(styrene-co-α-methyl styrene), which is known as a tackifier in rubber industry, is investigated using poly(butadiene) rubber (BR) and poly(styrene-co-butadiene) rubber (SBR). The films of pure rubbers and the blends with the tackifier were prepared by a solution-cast method using toluene as a solvent. Two sheets composed of different rubbers, in which the tackifier was mixed at least in one rubber sheet, were piled together and annealed beyond the glass transition temperature Tg of the tackifier. The transfer phenomenon of the tackifier between the sheets was evaluated by the peak shift in the tensile loss modulus E″ curve, ascribed to Tg of the rubbers, which was measured by the dynamic mechanical analysis. Moreover, crystallization temperature of BR was also employed as a measure of the transfer, because the tackifier retards the crystallization of BR. It is found that the tackifier moves from one rubber to another during annealing procedure to reduce severe localization. When the content is the same in each rubber, the tackifier immigrates from BR to SBR, suggesting a better miscibility with SBR. This behavior is attributed to the small difference in the solubility parameter between SBR and the tackifier as compared to that between BR and the tackifier. 相似文献
The process of cold seeding melt growth of GdBa2Cu3Oy (Gd123) bulk superconductors using NdBa2Cu3Oy (Nd123) thin films was reported. In addition, a novel cold seeding concept of combining MgO crystal and buffer pellet was also introduced. The misorientation caused by the lattice mismatch between MgO and Gd123 melt was overcome by choosing suitable heat treatment program and Gd2BaCuO5 (Gd211) content of the buffer pellet. The doping effect of soft ferromagnetic NiFe alloy particles was also reported. The bulk sample with 0.4% (mole fraction) doping amount shows the best performance on the flux trapping. The critical current density is largely enhanced under the external field of 1–2 T, which is promising for large-scale applications. This effect is originated from the substitution of Fe and Ni ions for the Cu sites contributing to magnetic flux pinning. 相似文献
The study presented in this paper concerns the influence of the counter materials on wear and friction performance of polytetrafluoroethylene (PTFE) reservoirs arranged in distinct patterns on coated surfaces. Al-bronze and Mo coatings were deposited on a mild steel substrate using an atmospheric plasma spray process. Three patterns of PTFE reservoirs were used. Pins, which served as counter surface, were made of three different materials. Wear tests were carried out in a pin-on-disc test rig at room temperature and under dry contact conditions. The tests were carried out at a constant pressure of 10 MPa. An average linear speed of the test disc was 0.036 m/s. The importance of appropriately matched hardness of two surfaces in sliding contact is emphasised. Due to inadequate hardness of the counter material, performance of Mo coating was adversely affected and expected beneficial action of PTFE reservoirs severely hindered. Al-bronze coating proved to be performing far better than Mo coating. Serious deterioration of Mo coating occurred faster than that for Al-bronze coating. 相似文献
Polycrystalline silicon (poly-Si) films thicker than 1.5 μm, consisting of dense small grains called nano-grain poly-Si (ngp-Si), are formed by flash lamp annealing (FLA) of amorphous silicon (a-Si) films prepared by catalytic chemical vapor deposition (Cat-CVD) method. Crystallinity of the ngp-Si films can be controlled by changing lamp irradiance. Secondary ion mass spectroscopy (SIMS) profiles of dopants in the ngp-Si films after FLA shows no serious diffusion. A minority carrier lifetime of over 5 μs is observed from these ngp-Si films after defect termination process using high pressure water vapor annealing (HPWVA), showing possibility of application for high-efficient thin film solar cells. 相似文献
A new technique to provide melt elasticity using flexible fine fibers prepared from a polymer with high melting point is demonstrated. A polymer composite of poly(propylene) with a small amount of fine fibers of poly(butylene terephthalate) shows marked strain‐hardening behavior in elongational viscosity, i.e., a rapid increase in the transient elongational viscosity with time or strain. The blend also shows prominent normal stress difference at steady shear. These elastic properties have not been observed for polymer composites with rigid fibers and can be applicable to the modification of rheological properties and thus the improvement of processability.
To test the effects of the annual fluctuation of the environmental factors on the starch properties in potato tuber development, starches were isolated from potato cultivars grown for ten consecutive years (2001–2010) on the experimental farm in Memuro, Hokkaido, the northernmost island of Japan. The median granule size, phosphorus content, and rapid visco‐analyzer pasting properties, peak viscosity, breakdown, and pasting temperature of these starches were analyzed. Daily temperature and precipitation records in Memuro were obtained from the Japan Meteorological Agency. Moreover, the correlation coefficients of yearly accumulated temperature and precipitation from flowering to harvesting with all the starch quality parameters were calculated. No relationships of accumulated temperature with median granule size, peak viscosity, and breakdown were found. The low phosphorus content was slightly associated with the high accumulated temperature. The pasting temperature was significantly and positively correlated with the accumulated temperature, suggesting that the pasting temperature strongly responds to the environmental temperature during potato tuber development. In contrast, all the starch quality parameters were almost irrespective of the precipitation during potato tuber development. 相似文献
Shotgun cloning of the Lactobacillus gasseri JCM 1131T whole DNA yielded two recombinant plasmids, p118gaY1 and p118gaY2, which directed cell lysis activity. Sequencing analysis revealed that the two plasmids carried almost identical inserted genes in following orders (truncated genes, in parentheses): in p118gaY1, (orf149)-orf92-holgaY-lysgaY-orf35-attL-(mnaAgaY1); in p118gaY2, (orfXgaY1)-orf169-orf149-orf92-holgaY-lysgaY-orf35-attP-(intgaY). The lysgaY-encoded protein (designated as LysgaY, 33.7 kDa) showed significant homology with putative muramidases (peptidoglycan-degrading enzyme) of the Lactobacillus phage phiadh, Lj965, Lj928, LL-H, mv4, and mv1. By zymogram analysis, LysgaY overproduced in Escherichia coli exhibited lytic activity towards 17 Gram-positive bacterial strains, including lactobacilli, lactococci, and staphylococci. The holgaY-encoded protein (15.7 kDa) contained three potential transmembrane helices, resembling putative holins (cytoplasmic membrane-disrupting protein) of Lj928 and Lj965. On the other hand, another clone p118gaYR obtained by EcoRI-shotgun cloning carried the (ptsCgaY1)-attR-(intgaY) genes. Three sequences, attL, attP, and attR, had a 47-bp common (core) sequence, and the core of attR was located in 3' region of a potential tRNA(Arg) gene. These results suggested that (i) attL and attR are phage-host junctions, left- and right-arms, respectively, (ii) attP is a phage attachment site, and (iii) intgaY is an integrase gene for phage integration and/or excision. After mitomycin C-induction, phage particles were demonstrated by electron microscopy. The prophage (phigaY) is somewhat leaky in the host, and has the two-component lysis system (HolgaY-LysgaY), closely resembling that of Lj928 as well as Lj965. 相似文献