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991.
Ezoe Y Moriyama T Ogawa T Kakiuchi T Mitsuishi I Mitsuda K Aoki T Morishita K Nakajima K 《Optics letters》2012,37(5):779-781
Large-aperture focusing of Al K(α) 1.49 keV x-ray photons using micropore optics made from a dry-etched 4 in. (100 mm) silicon wafer is demonstrated. Sidewalls of the micropores are smoothed with high-temperature annealing to work as x-ray mirrors. The wafer is bent to a spherical shape to collect parallel x rays into a focus. Our result supports that this new type of optics allows for the manufacturing of ultralight-weight and high-performance x-ray imaging optics with large apertures at low cost. 相似文献
992.
Tomohiro Uchiyama 《代数通讯》2018,46(3):1333-1343
Let k be a nonperfect separably closed field. Let G be a connected reductive algebraic group defined over k. We study rationality problems for Serre’s notion of complete reducibility of subgroups of G. In particular, we present a new example of subgroup H of G of type D4 in characteristic 2 such that H is G-completely reducible but not G-completely reducible over k (or vice versa). This is new: all known such examples are for G of exceptional type. We also find a new counterexample for Külshammer’s question on representations of finite groups for G of type D4. A problem concerning the number of conjugacy classes is also considered. The notion of nonseparable subgroups plays a crucial role in all our constructions. 相似文献
993.
The photolysis of CH3OH/Cl2/air, CH3OH/Cl2/NO2/air, and (CH3)2CHOH/Cl2/NO2/air at 28 ± 2°C was studied using the long-path FTIR method. The primary reactions of methanol and isopropanol with Cl atoms were α-hydrogen abstraction (100%), and α hydrogen (85%), and α-hydrogen abstraction (15%), respectively. The failure to detect hydroxyalkyl-peroxy nitrates suggested that the oxygen addition to α-hydroxy radicals is not important. From the product distribution an upper limit of the ratio of oxygen addition to CH2OH and CH3CHOH was estimated to be about 6 and 7%, respectively. The oxygen addition ratio to (CH3)2COH was very low. The reaction mechanism is also discussed. 相似文献
994.
995.
The phase transition behavior and the structural properties of a thermotropic polyester, poly-(chloro-1,4-phenylene-trans-1,4-cyclohexanedicarboxylate), were studied by differential scanning calorimetry, x-ray diffraction, polarized-light microscopy, and electron microscopy. The polyester shows two first-order transitions in heating, i.e., a crystal-crystal transition and a crystal-liquid-crystal transition at 190–220 and 300–330°C, respectively. The texture in the liquid-crystalline phase is very similar to that of nematic low-molecular-weight materials. Oriented films of the polyester can be obtained from the liquid-crystalline state. Many fibrils occur in a fractured lateral surface of the film. Bandlike structures 50–100 nm wide were observed in surfaces of both oriented and unoriented films. The direction of the polymer chain axis is almost perpendicular to that of band elongation. In the oriented film, the band structures are perpendicular to the direction of orientation. 相似文献
996.
Tomohiro Ohta 《国际化学动力学杂志》1984,16(7):879-886
Relative rate constants for the reactions of hydroxyl radicals with a series of alkyl substituted olefins were measured by competitive reactions between pairs of olefins at 298 ± 2 K and 1 atmospheric pressure. Hydroxyl radicals were produced by the photolysis of H2O2 with 254-nm irradiation. The obtained rate constants were (× 10?11 cm3 molecule?1 s?1): 2.53 ± 0.06, propylene; 5.49 ± 0.17, cis-2-butene; 5.47 ± 0.1, isobutene; 6.46 ± 0.13, 2-methyl-1-butene; 6.37 ± 0.16, cis-2-pentene; 6.23 ± 0.1, 2-methyl-1-pentene; 8.76 ± 0.14, 2-methyl-2-pentene; 6.24 ± 0.08, trans-4-methyl-2-pentene; 10.3 ± 0.1, 2,3-dimethyl-2-butene; 9.94 ± 0.1, 2,3-dimethyl-2-pentene; 5.59 ± 0.07, trans-4,4-dimethyl-2-pentene. A trend in alkyl substituent effect on the rate constant was found, which is useful to predict kOH on the basis of the number of alkyl substituents on the double bond. 相似文献
997.
The photooxidation of chloral was studied by infrared spectroscopy under steady-state conditions with irradiation of a blackblue fluorescent lamp (300 nm < λ < 400 nm, λmax = 360 nm) at 296 ± 2 K. The products were hydrogen chloride, carbon monoxide, carbon dioxide, and phosgen. The kinetic results reveal that the reaction proceeds via chain reaction of the Cl atom: The results lead to the conclusion that mechanism (B) is confirmed to be more likely than mechanism (A), which was favored at one time by Heicklen for the mechanism of the oxidation of trichloromethyl radicals by oxygen molecules: The ratio of the initial rates of CO and CO2 formation gave k7/k6 = 4.23M?1, and the lower limit of reaction (5) was found to be 3.7 × 108M?1 sec?1. 相似文献
998.
Hiroko Kyotani Hisaaki Kanetsuna Masanao ya 《Journal of Polymer Science.Polymer Physics》1977,15(6):1029-1036
Conditions that affect the conformation of poly(β-benzyl L-aspartate) in films have been studied. A slow transition from the left-handed to the right-handed α-helical form is observed under certain conditions in half-dried film cast from chloroform solutions and after exposure of amorphous films of the left-handed β-helical form to chloroform vapor. This transition is caused by adsorption of moisture. Thermal transitions of these films were examined by differential scanning calorimetry and infrared spectroscopy. The right-handed α-helices change to left-handed ω-helices around 140°C, and sharp exothermic peak is observed in this region for some films. 相似文献
999.
Mutsumasa Kyotani Shigenobu Mitsuhashi 《Journal of Polymer Science.Polymer Physics》1972,10(8):1497-1508
The relative amounts of the α and the γ crystalline forms of nylon 6 obtained from the melt under different crystallization conditions have been studied by an x-ray diffraction procedure by comparison with a calibration curve obtained from the diffraction of standard samples. The weight fraction of the α form decreases with increasing crystallization temperature and that of the γ form increases. Growth of the α form is predominant in crystallization at 100°C and of the α form at 200°C. The amount of the α form tends to increase on annealing at 200°C for specimens crystallized at any temperature. 相似文献
1000.
Kazukiyo Kohno Tomohiro Tsunada Hideyuki Seto Michio Tanaka 《Finite Elements in Analysis and Design》1991,7(4):279-290
This paper is concerned with the hybrid method of boundary element and finite element techniques by means of an “external-super-element” function of the commercial finite element method code
. The proposed super-element method preserves the modelling simplicity of the boundary element method and the generality of
. Two- and three-dimensional elastostatic analyses are performed to demonstrate the accuracy of this method as well as its applicability to practical problems. 相似文献