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71.
Microscale silicon structures oriented along <100> and <110> orientations were laser treated with different conditions with the cross section shape and tensile strength investigated after the treatment. Finite element simulation was performed to examine the temperature distribution at different conditions during laser treatment. Using a low energy (1.2 J/cm2) and high tilt angle (65°) led to a more preserved cross section with a slight strength improvement. The strength improvement was limited due to other surfaces that were not affected by laser treatment. An improvement of 30 % in tensile strength was achieved with a higher energy (4 J/cm2) lower tilt angle (45°) treatment that was consistent for different sample orientations. The cross section of the samples treated at such condition was significantly changed however. The effect of sample orientation on fracture behaviour was studied and unstable crack propagation was observed for <100> oriented samples that was more significant after laser treatment. 相似文献
72.
Unstable chemical species, that is, radicals generated by the thermal treatment of a dimethyl sulfoxide (DMSO) solution of the lignin of a softwood, Yezo spruce (Picea jezoensis Carr.), were studied in detail with an electron spin resonance (ESR) method combined with a spin‐trapping technique. An unstable secondary carbon radical (~CH ·) in the solution was trapped as a stable nitroxide spin adduct [R? (N? O ·)? CH~ (R = tert‐butyl benzene)] when the DMSO solution was heat‐treated in the presence of a spin‐trapping reagent [2,4,6‐tri‐tert‐butylnitrosobenzene (BNB)] at about 40°C. This meant that alkyl phenyl ether bonds (~CH? O‐phenyl), known as interunitary lignin bonds, were homolytically scissioned by the thermal treatment in the lignin solution. A detailed analysis of the ESR spectrum revealed that three kinds of radicals—primary (~CH2 ·), secondary (~CH ·), and tertiary (~C ·) carbon radicals—were trapped as stable spin adducts at about 60°C, although the phenoxy radical (Ph? O ·) was not trapped by the BNB spin trap as the counter radical of the secondary carbon radical. This suggested that a fairly large steric hindrance existed between the so‐called guaiacoxy radical with a methoxy group in the ortho position and the BNB molecule bearing two butyl groups as bulky moieties in the ortho positions. However, the phenoxy radicals in the lignin solution were stable up to about 60°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2136–2141, 2004 相似文献
73.
Yoshinobu Nakamura Haruo Tabata Hideto Suzuki Kazuo Iko Masayoshi Okubo Tsunetaka Matsumoto 《应用聚合物科学杂志》1986,32(5):4865-4871
In order to reduce the internal stress in a cured epoxy resin, the submicron polymer particles were dispersed therein prior to curing. For this purpose, four kinds of poly(butyl acrylate), poly(methyl methacrylate) core-shell particles were prepared by seeded emulsion polymerization for methyl methacrylate with poly(butyl acrylate) seed particles having different particle diameter, and subsequently were powdered by drying at room temperature. It was observed by SEM that poly(butyl acrylate) particles as core were dispersed in the cured epoxy matrix. Poly(methyl methacrylate) as shell seems to dissolve in the matrix. The internal stress of cured epoxy resin decreased with the modification of the particles and the tendency was enhanced with a decreasing in the particle diameter. 相似文献
74.
Polyynes were synthesized by laser ablation of diamond particles with various sizes suspended in ethanol. Chain length distributions and total yields of polyynes produced were compared with those produced from graphitized diamond particles and graphite particles. The relative amounts of long polyynes such as C14H2 and C16H2 produced from diamond particles were found to be larger than those from graphitized diamond particles and graphite particles. From the change of the chain length distribution with the laser irradiation time, it is concluded that the long polyynes are produced directly from diamond particles at the initial stage of ablation. Furthermore, the total yield of polyynes was found to increase with the size of diamond particles and decrease as their graphitization proceeds. Possible mechanisms of these results are discussed. 相似文献
75.
Praveen Singh Thakur Koji Sugano Toshiyuki Tsuchiya Osamu Tabata 《Microsystem Technologies》2014,20(3):403-411
The effect of in- and anti-phase mode decoupling on the frequency response of coupled in-plane resonators was examined, experimentally, to suppress the acceleration sensitivity (acceleration output) in tuning fork gyroscopes (TFGs). Finite element simulations, conducted in our recent works, show that the origin of acceleration sensitivity for the sensing resonators in TFGs lies in the transduction of linear (in-phase) acceleration to anti-phase resonant vibration of the sensing resonators in TFGs. We further revealed that the frequency decoupling of the in- and anti-phase vibration modes is effective in suppressing the transduction. To experimentally validate this, two types of coupled resonators (one coupled with a frame and the other with a spring) to represent the sensing resonators of TFGs were fabricated on silicon-on-insulator wafer. Different resonant frequencies were used to evaluate the frequency decoupling effect on the coupled resonators, i.e., the coupling from in-phase mode oscillation to the anti-phase mode vibration. The vibration amplitude of the anti-phase mode increased in the coupled resonators with small frequency decoupling (decoupling ratio, DR) value. Additionally, the two types of coupled resonators exhibit similar output after considering the effect of decoupling ratio, anti-phase frequency and different stiffness unbalances. Our results reveal that TFG can be designed with lower acceleration sensitivity by utilizing sense resonators with large decoupling ratio, higher anti-phase frequency, and possessing structures which are insensitive to fabrication imperfections. 相似文献
76.
Polyethylene was mechanochemically produced by milling of alumina powder at room temperature in the presence of ethylene monomer. Nearly 50% of the produced polyethylene was chemically bonded with the matrix of the alumina. The other 50% of the polymer was extracted by the organic solvents. The polyethylene extracted by the hot n-heptane was characterized as having a structure similar to that of the branched polyethylene of low density, and the toluene extracted polyethylene had a structure similar to that of the high density polyethylene. The molecular weights of the mechanochemically produced polyethylene were found to distribute from 102 to 106 by gel permeation chromatography. The weight average molecular weight was estimated as 260,000 after the 3 days milling. Mechanochemical polymerization of ethylene was also demonstrated by milling of silica in the presence of ethylene monomer. Polymerization of propylene by milling of alumina under propylene atmosphere was performed. The obtained polymer was found to be an atactic by IR measurement and the molecular weight of the extracted product was determined as ? 400 by the vapor pressure osmometer. 相似文献
77.
Role of supported metals in the selective reduction of nitrogen monoxide with hydrocarbons over metal/alumina catalysts 总被引:3,自引:0,他引:3
HideakiHamada Yoshiaki Kintaichi Megumu Inaba Mitsunori Tabata Tomohiro Yoshinari Hiroshi Tsuchida 《Catalysis Today》1996,29(1-4):53-57
The promoting effect of supported metals on alumina catalyst was investigated for the reduction of nitrogen monoxide in oxygen-rich atmospheres. For NO reduction with propene over impregnated CoO/A12O3, the first reaction step was found to be the oxidation of NO to NO2 probably catalyzed by dispersed cobalt species. The next reaction step, which is the reaction of NO2 with propene to form N2, was considered to take place on the alumina surface. Although the activity of impregnated FeO/A12O3 was low because of the presence of large iron oxide particles catalyzing propene oxidation with dioxygen, FeO/A12O3 prepared with sol-gel method showed excellent deNOx activity. 相似文献
78.
A new anti-biofouling ozone system which intermittently supplies high-concentration ozone was demonstrated to be effective for preventing marine biofouling in test cooling tubes (titanium, aluminum brass and epoxy-coated PVC) simulating condenser and intake conduit systems of power plants. Injection of ozone of about 5 mg/L for five minutes once each day was enough to keep them clean. Corrosion of titanium and aluminum brass tubes after the three-month test was found tobe negligible. 相似文献
79.
S Higashi N Tabata KH Kondo M Kai K Miyamoto Y Maeda T Setoguchi 《Canadian Metallurgical Quarterly》1999,81(2):243-248
OBJECTIVE: To determine the effect of the surgeon and the wavelength of laser used on the response to focal photocoagulation for diabetic macular edema. DESIGN: Retrospective case-control study. PARTICIPANTS: Forty-four matched pairs of cases by two different retina surgeons in the study of surgeon influence were examined. Sixty-nine matched pairs of cases using dye yellow versus argon green laser treatment in the study of wavelength influence also were studied. In both studies, eyes were matched for the only patient-dependent variables affecting outcome: age, initial visual acuity, follow-up time, and diabetic control by diet versus any other method. INTERVENTION: Focal laser photocoagulation for clinically significant diabetic macular edema was performed. MAIN OUTCOME MEASURE: Visual acuity at 6 months follow-up was measured. RESULTS: For the study in which the only difference was the surgeon, at 6 months follow-up the mean difference in logarithm of the minimum angle of resolution (logMAR) visual acuity was -0.045, 95% confidence interval (-0.160, 0.070). For the study in which wavelength varied, at 6 months the mean difference in logMAR visual acuity was -0.048, 95% confidence interval (-0.147, 0.052). The power of the surgeon study to detect a difference in the logMAR visual acuity of 0.3 is 88% and of the wavelength study to detect this difference is 99%. CONCLUSION: In looking at the 6-month visual outcome after focal laser photocoagulation for clinically significant diabetic macular edema, different fellowship trained surgeons and the choice of green or yellow wavelength had no effect on the treatment outcome. 相似文献
80.