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81.
Inner shell ionization cross sections by low-energy positron impact have been measured. Development of an x-ray detector with thin Si(Li) crystals has enabled the first measurements of the absolute cross sections for the positron impacts in the energy range below 30 keV. Threshold behavior of the measured cross sections for the Cu K shell and Ag L shell are compared with the theoretical results of Gryzinski and Kowalski [Phys. Lett. A 183, 196 (1993)]] and Khare and Wadehra [Can. J. Phys. 74, 376 (1996)]]. Good agreement has been found for the Cu K shell, while the experimental values for the Ag L shell were found to be smaller than the corresponding theoretical results. 相似文献
82.
83.
We show that modulational instability may arise even in the normal group-velocity dispersion regime of an optical fiber when the fiber loss (gain) varies depending on the wavelength. A simple analytical expression for the instability gain is obtained, which reveals that the odd-order terms of the loss dispersion are responsible for this phenomenon. The instability gain is measured experimentally in an optical-parametric-amplification configuration. Large parametric gain is induced in a non-phase-matched regime as we apply narrow band loss at the idler wavelength. 相似文献
84.
The effect of temperature perturbation on a single-chain-collapse process was studied for poly(methyl methacrylate) with the molecular weight M(w)=1.05 x 10(7) in the mixed solvent of tert-butyl alcohol+water (2.5 vol %). In the chain-collapse process after a quench from the theta; temperature to a temperature T(1), the temperature was changed from T(1) to T(2) at the time t(1) after the quench and returned to T(1) at the time t(1)+t(2). In the three stages at T(1), T(2), and T(1), measurements of the mean-square radius of gyration of polymer chains were carried out by static light scattering and the chain-collapse process was represented by the expansion factor as a function of time. An effect of chain aggregation on the measurements was negligibly small because of the very slow phase separation. For the negative temperature perturbation (T(1)>T(2)), the chain-collapse processes observed in the first and third stages were connected smoothly and agreed with the collapse process due to a single-stage quench to T(1). A memory of the chain collapse in the first stage at T(1) was found to persist into the third stage at the same temperature T(1) without being affected by the temperature perturbation of T(2) during t(2). The memory effect was observed irrespective of the time period of t(2). The positive temperature perturbation (T(1)相似文献
85.
The big surface pores of a porous stainless steel (PSS) tube filter with marked roughness were jammed with aluminium hydroxide gel by a combination of ultrasonic vibration and vacuum suction, then a thin dense Pd membrane (6 microm) was plated in-situ on this pre-jammed filter by a multi-dimensional plating mechanism; after recovering the substrate pores by high temperature treatment, higher H2 permeance and complete H2 selectivity were obtained. 相似文献
86.
[reaction: see text] The Heck reaction is a more efficient and reliable method than previous ones for introducing a C3 unit at the benzyl position for the synthesis of Beraprost. Especially, trialkylated long-chain amines such as (n-C(8)H(17))(3)N and (n-C(12)H(25))(3)N resulted in good yields. This development will be used for the industrial synthesis of Beraprost. 相似文献
87.
Strength characteristics of the self-sustained wave in grooved channels with different groove length
Faming Sun Yongning Bian Hirofumi Arima Yasuyuki Ikegami Xinsheng Xu 《Heat and Mass Transfer》2010,46(11-12):1229-1237
The self-sustained oscillations arising in a series of grooved channels are investigated experimentally. Pressure drop, time-averaged and time-various local pressure in the grooved channels with six kinds of groove length are measured with the differential transducer and the pressure sensor, respectively, and the flow structures are visualized using the aluminum dust method. The local pressure signal shows that the self-sustained wave appears in the first or second frequency, and the Strouhal number, based on the nature frequency of the self-sustained wave, is almost equivalent for the first or second frequency in the same channel. Meanwhile, the Strouhal number for each channel decreases monotonously with the groove length. Furthermore, it is found that increasing pressure will result in higher amplitude of the self-sustained wave, this behavior is significant for the efficient heat transfer in practical engineering. 相似文献
88.
Manabu Nakazono Yasuyuki Sato Shigeo Hasegawa Norimasa Arisuda Aiko Miyamoto Kiyoshi Zaitsu 《Chromatographia》2009,70(5-6):933-937
Rapid separation of hydrophobic compounds such as bisindolylmaleimides, indolocarbazoles or fullerene C60 derivatives by ultra performance liquid chromatography was developed. Bisindolylmaleimides and indolocarbazoles were separated within 7 and 5 min, respectively. The linear ranges for the determination of bisindolylmaleimides and indolocarbazoles were 1.25?500 pmol and 0.5?50 pmol per injection (r > 0.99), respectively. Fullerene C60 derivatives were separated within 9 min, and the linear range for the determination of fullerene C60 derivatives was 0.1?10 pmol per injection (r > 0.99). 相似文献
89.
Effect of refraction index and thickness of the light guide in the position-sensitive gamma-ray detector using compact PS-PMTs 总被引:1,自引:0,他引:1
Koji Inoue Haruo Saito Yasuyuki Nagashima Toshio Hyodo Yasuyoshi Nagai Shinichi Muramatsu Shota Nagai 《Radiation Physics and Chemistry》2000,58(5-6):763-766
We constructed a position-sensitive gamma-ray detector consisting of an array of BGO scintillators, a light guide and compact PS-PMTs. The effects of refractive index and thickness of the light guide of a glass plate on the detector performance were investigated. A light guide with higher refractive index and smaller thickness is found better for a good spatial resolution. 相似文献