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1.
Mechanical properties of sinter-forged Al2O3-ZrO2 ceramics 总被引:1,自引:0,他引:1
Two kinds of composites, Al2O3-25 wt% ZrO2(2 mol% Y2O3) (Y-ZTA), Al2O3-25 wt% ZrO2(8 mol% CeO2) (Ce-ZTA) were produced by the sinter-forging process. The effect of presintering temperature on the mechanical properties of the composites was examined. The sinter-forging process increased the room-temperature bending strength in comparison with pressureless sintering, owing to the smaller grain size in sinter-forged bodies than in pressureless sintered ones. It was found necessary to keep the presintering temperature considerably lower than sinter-forging temperature in order to improve the room-temperature strength. The strength of sinter-forged Ce-ZTA was higher than that of sinter-forged Y-ZTA. The residual surface compressive stress induced by the phase transition during grinding in Ce-ZTA was found to be effective to further improve the strength and fracture toughness. 相似文献
2.
C Nishiyama M Fukada Y Usui N Iwamoto T Yuuki Y Okumura H Okudaira 《Canadian Metallurgical Quarterly》1995,32(14-15):1021-1029
Der f 2 is a major mite allergen composed of 129 amino acid residues. To determine the major epitopes on Der f 2 recognized by human IgE antibodies, artificial mutations were introduced to Der f 2 protein. The IgE-binding activity of Der f 2 was significantly decreased by deletion of 10 amino acids at the N-terminus or nine amino acids at the C-terminus. Site-directed mutagenesis with a single amino acid replacement by Ala or Leu in both N- and C-terminal regions as well as a central portion was performed to generate 42 single-site mutations. Amino acid replacement around a disulfide bond of Cys8-Cys119 caused a marked decrease in IgE-binding activity. Furthermore, a distinct decrease in IgE-binding was also caused by Ala-substitution close to a disulfide bond of Cys73-Cys78 and by mutations of a few charged residues. From these results, it was concluded that the two disulfide-forming regions of Der f 2 and several charged residues are important for forming major epitope structures recognized by human IgE antibodies. 相似文献
3.
T Sakai A Konishi T Nishiyama T Higashizawa H Bito 《Canadian Metallurgical Quarterly》1998,47(8):998-1001
Effectiveness in visualization of the vocal cord during orotracheal intubation with McCoy (McC) compared with Macintosh (Min) and Miller (Mil) blades were investigated. After an institutional review board approval, 117 patients for elective surgery under general anesthesia requiring tracheal intubation were investigated. Five board certified anesthesiologists tried to visualize the vocal cord of a patient three times with the three different types of laryngoscope. Total of 351 intubation attempts were studied. The view obtained at laryngoscopy with each of the three blades was recorded as follows. Grade 1. If most of the glottis is visible. Grade 2. If only the posterior extremity of the glottis is visible. Grade 3. If no part of the glottis can be seen. Grade 4. If not even the epiglottis can be exposed. Eight-two Grade 1 views were obtained with McC, 72 with Mil and 47 with Min, respectively. Thirty-three Grade 2 views were obtained with McC, 36 with Min and 24 with Mil. Two Grade 3 views with McC, 34 with Min and 14 with Mil were obtained. Seven Grade 4 views were obtained with Mil. The grades of laryngeal visualization with McC were significantly lower than those with Min and Mil. 相似文献
4.
5.
Formation of carbon on nickel sheet from benzene vapor carried by hydrogen was studied at a temperature range from 520 to 730°C. A maximum rate was observed at about 630°C, above which the deposition rate decreased rapidly. The carbon formed was hydrogenated in situ. Methane was the main gaseous product and a maximum rate was observed at about 670°C. Very high reactivity of deposited carbon toward hydrogenation was ascribed to the catalytic action of nickel particles dispersed in the carbon. The hydrogenation rates were divided into three zones and possible interpretations are discussed. A mechanism which is a reverse process to deposition was suggested. The decrease of the hydrogenation rate at higher temperatures was due to the equilibrium among carbon, hydrogen and methane, where carbon was more reactive than graphite. 相似文献
6.
Poly(n-butyl acrylate) (PnBA) chemically crosslinked with tetraethylene glycol dimethacrylate (TEGDM) and physically crosslinked PnBAs produced by neutralization of poly(n-butyl acrylate-stat-acrylic acid) with NaOH or Ca(OH)2 were prepared as a polymer I network. Each polymer I was swollen with styrene and cured in situ into semi-IPN-TEGDM, semi-IPN-Na, or semi-IPN-Ca, respectively. Both physically crosslinked polymers maintained their shapes during the swelling procedure. Dynamic mechanical spectroscopy indicated that good mixing of the two polymers took place in the semi-IPN-Ca as well as in semi-IPN-TEGDM, but a distinct phase separation occurred in the semi-IPN-Na. These results were supported by their transparent or optical opaque appearances, respectively. Annealing at 180°C developed further phase separation in the semi-IPN-Na, but very little in the semi-IPN-Ca. Analyses by the incompatibility number (based on the modulus–temperature curve) and the calculation of individual phase compositions (from the glass transition temperature shifts) were used in estimating the extent of molecular mixing. 相似文献
7.
Ken-ichi Kumagai Kenji Kawano Isao Watanabe Kusuo Nishiyama Kanetada Nagamine 《Journal of Superconductivity》1994,7(1):63-67
Muon spin rotation (
+SR) measurement provides clear evidence of the antiferromagnetic order of Cu moments below 35 K for La2–x
Ba
x
CuO4 and below 15 K for La2–x
Sr
x
CuO4 in the narrow range ofx where the high-T
c
superconductivity (SC) is suppressed remarkably. The results suggest that the change of the electronic state coupled with the lattice instability is relevant to the local suppression of SC and freezing of spin fluctuations of the Cu moment. 相似文献
8.
Artificial Life and Robotics - In recent years, unspecified messages posted on social media have significantly affected the price fluctuations of online-traded products, such as stocks and virtual... 相似文献
9.
This note examines testing methods for Paretoness in the framework of rank-size rule regression. Rank-size rule regression describes a relationship found in the analysis of various topics such as city population, words in texts, scale of companies and so on. In terms of city population, it is basically an empirical rule that log?(S(i)) is approximately a linear function of log?(i) where S(i) is the number of population of i th largest city in a country. This is closely related to the so-called Zipf’s law. It is known that this kind of empirical observation is found when the city population is a random variable following a Pareto distribution. Thus one may be willing to test if city size has a Pareto distribution or not. Rosen and Resnick [K.T. Rosen, M. Resnick, The size distribution of cities: an explanation of the Pareto law and primacy, Journal of Urban Economics 8 (1980), 165–186] and Soo [K.T. Soo, Zipf’s law for cities: a cross country investigation, Regional Science and Urban Economics (35) 2005, 239–263] regress log?(S(i)) on log?(i) and log?2(i) and test the null of Paretoness by standard t-test for the latter regressor. It is found that t-statistics take large values and the Paretoness is rejected in many countries. We study the statistical properties of the t-statistic and show that it explodes asymptotically, in fact, by simulation and thus the t-test does not provide a reasonable testing procedure. We propose an alternative test statistic which seems to be asymptotically normally distributed. We also propose a test with the null hypothesis that the city size distribution is Pareto with exponent unity, which is a modification of the F-test. 相似文献
10.
In a field study an adjustable VDT workstation was given to each of the 68 operators for one week. The preferred settings, the body postures and subjective evaluations were assessed during normal working activities of the operators. The preferred ranges disclose the following figures: keyboard height (home row above floor) 71-87 cm, screen height (centre above floor) 92-116 cm, viewing angles (eye to screen centre) + 2 to -26 degrees, visual distance (eye to screen) 61-93 cm. There was practically no correlation between preferred settings and anthropometric data of body length or eye levels above floor. The study of body postures revealed that the great majority of operators tend to lean backwards with trunk inclinations between 97 degrees and 121 degrees (95% confidence interval). Some of the preferred settings strongly differ from those recommended in many brochures and standards. The physical complaints in the neck-shoulder and back area are diminished with the preferred settings. 相似文献