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991.
The applicability of laser processing for small-lot micro-electromechanical system devices is discussed in this paper. This simple process could replace conventional complex processes designed with mass production in mind. Ablation, protrusions or surface modification is revealed to occur by argon ion laser scanning into silicon. Which of them occurs depends on the laser power. It is found that the protrusions are covered by a thin layer of oxide; however, oxidation of the modified surface is not established even though some results suggest it. Surface modification is more applicable to surface patterning than coarse protrusion is because the laser-modified surface can be used as a mask in KOH etching to make sharp patterns. The applicability of this method is indicated by demonstrating pattern width control, patterning over a large area and the fabrication of a 16-bit linear scale. 相似文献
992.
Takashi Nagatani 《Physica A》2009,388(14):2911-2921
We study the dynamic behavior of vehicular traffic through a series of traffic lights on selected paths in a two-dimensional (2d) traffic network. The city traffic network is made of one-way perpendicular streets arranged in a square lattice with traffic signals where vertical streets are oriented upwards and horizontal streets are oriented rightwards. A vehicle moves through the series of signals on a path selected by the driver. The selected path is one of the straight, zigzag, and random paths in a 2d traffic network. The vehicular motion on a selected path is presented by the nonlinear-map model. Vehicular traffic exhibits very complex behavior with varying selected paths, cycle times, and vehicular density. The dependence of the arrival time on cycle time, selected path, and density is clarified for 2d city traffic. 相似文献
993.
Angular and spatial profiles of undulator radiation have been investigated to derive a universal function that evaluates the brilliance of undulator radiation and takes into account the effects of electron beam emittance and energy spread. It has been found that the effects of energy spread on the angular divergence and source size can be expressed by simple analytic expressions, and a universal brilliance function has been derived by convolution with the electron beam distribution functions. Comparisons with numerical results have been carried out to show the validity and applicability of the universal function. 相似文献
994.
Takashi Harumoto Javed Iqbal Xiaofang Liu Ji Shi Yoshio Nakamura Ronghai Yu 《Applied Physics A: Materials Science & Processing》2009,97(1):211-215
Co doped SnO2 nanoparticles have been prepared via a wet chemical method with different precipitation processes. The structure and morphology
of Co doped SnO2 nanoparticles demonstrate that the nanoparticles are in a rutile single phase and uniform, respectively. X-ray photoelectron
spectroscopy shows that the Co dopants are in 2+ oxidation valence state and doped ∼2 atm% in SnO2 nanoparticles. Moreover, Raman spectroscopy further confirms that Co doped SnO2 nanoparticles have single phase crystallinity without forming any extra modes related to secondary phases. The magnetic measurements
reveal that all nanoparticles exhibit room temperature ferromagnetism (RTFM) due to the presence of disorders and defects
introduced by hydroxyls in the crystal structure. In addition, it has been clearly observed that the saturated magnetic moments
are strongly affected by the precipitation processes which control the incorporation of hydroxyls into the lattice. 相似文献
995.
Kazuaki Sakoda Takashi Kuroda NaokiI keda Takaaki Mano Yoshimasa Sugimoto Tetsuyuki Ochiai Keiji Kuroda Shunsuke Ohkouchi Nobuyuki Koguchi Kiyoshi Asakawa 《中国光学快报(英文版)》2009,7(10):879-881
We fabricate photonic crystal slab microcavities embedded with GaAs quantum dots by electron beam lithography and droplet epitaxy. The Purcell effect of exciton emission of the quantum dots is confirmed by the micro photoluminescence measurement. The resonance wavelengths, widths, and polarization are consistent with numerical simulation results. 相似文献
996.
A method to characterize attosecond extreme ultra violet (XUV) pulses from photoelectron spectra of atoms is presented. A pump pulse prepares a coherent superposition of two atomic bound states, from which photoionization takes place after variable time delays by the attosecond XUV pulse. Information on the spectral phase of the attosecond XUV pulse is extracted from the analysis of photoelectron spectra as a function of photoelectron energy and time delay. Together with information on the spectral intensity obtained from a separate optical measurement, a temporal shape of the attosecond XUV pulse can be precisely reconstructed. After the theoretical formulation of the problem, we present numerical examples for H atom and show that, depending on the choice of energy separation of two bound states, a different accuracy is reached to characterize attosecond XUV pulses. 相似文献
997.
Mariame A. Hassan Loreto B. Feril Kosho Suzuki Nobuki Kudo Katsuro Tachibana Takashi Kondo 《Ultrasonics sonochemistry》2009,16(3):372-378
Three novel lipid-shell-type microbubbles (MBs), AS-0100, BG6356A and BG6356B, have been evaluated for their impact on ultrasound (US)-induced cell death and free radicals production. Previously studied and well-characterized US exposure conditions were employed in which human myelomonocytic lymphoma U937 cells were exposed to 1 MHz pulsed US beam (0.3 W/cm2, 10% duty factor) for 1 min with or without MBs. Three different concentrations of each MB were used. Apoptosis and cell lysis were assessed by examining phosphatidylserine externalization and by counting viable cells, respectively, 6 h post-exposure. Free radicals production and scavenging activities were evaluated using electron paramagnetic resonance (EPR)-spin trapping. The results showed that only AS-0100 and BG6356A were able to enhance the US-induced apoptosis, mainly by increasing the secondary necrosis. Apoptosis and cell lysis seemed to depend more on mechanical forces exerted by oscillating MBs while free radicals played a trivial role. BG series MBs exhibited pronounced scavenging activities. Generally, despite the need for further optimization, AS-0100 and BG6356A appear to be promising as adjuncts in cases where US-induced cell death is required. 相似文献
998.
999.
Saburo Yuasa Masaru Kawashima Takashi Sakurai 《Proceedings of the Combustion Institute》2009,32(2):1929-1936
To examine the pyrophoric characteristics of Mg powder, we generated ultra-fine Mg particles (average particle diameter: about 0.3 μm) without an original oxide coat in an Ar stream. The ignition of the powder was measured by using the impinging O2/N2 mixture streams over a wide range of the experimental parameters: pressure, oxygen concentration and velocity of the streams. The Mg powder was found to ignite even at room temperature. The spontaneous ignition temperatures in the range of 278 324 K were insensitive to all the experimental parameters. The ignition delay time had a tendency to decrease with increasing experimental parameters.The ignition process of the Mg powder was found to be controlled by the surface reaction rate without an oxide coat. We proposed a new ignition hypothesis considering a critical oxide thickness on the Mg powder particles at the transition temperature from protective to non-protective nature: that is, the ignition of the Mg powder occurs when the powder temperature rises above the transition temperature before surface reactions form a protective oxide coat with the critical thickness on the individual particle surfaces. According to this hypothesis, an ignition model of Mg powder cluster was developed, and the relation between the spontaneous critical ignition temperature and the ultra-fine powder size, depending on the critical thickness of the protective oxide coat, was clarified. The critical oxide thickness was estimated. 相似文献
1000.
结合氢在GaN中的扩散特性,运用阴极荧光(CL)谱,对氢化前后低能电子束辐照下GaN带边发光强度的演变进行了研究.实验发现,氢化前GaN在低能电子束辐照下带边发光强度呈现衰减的趋势,而氢化后带边发射强度先上升后衰减,而且氢化后的衰减比氢化前弱.1 h辐照过程中,氢化后GaN带边发光强度的变化比氢化前要小很多.另外,实验中发现经过氢化处理的GaN在辐照后20 h内没有观察到带边发射强度的恢复.研究表明氢原子在GaN中可以钝化缺陷来增强发光,但这种钝化缺陷的作用必须通过克服高的扩散势垒来实现,而低能电子束可以
关键词:
阴极荧光
低能电子束
氢化
演变 相似文献