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排序方式: 共有624条查询结果,搜索用时 15 毫秒
91.
We introduce an approach to implement full coherent control on nanometer length scales. It is based on spatiotemporal modulation of the surface plasmon polariton (SPP) fields at the thick edge of a nanowedge. The SPP wavepackets propagating toward the sharp edge of this nanowedge are compressed and adiabatically concentrated at a nanofocus, forming an ultrashort pulse of local fields. The profile of the focused waveform as a function of time and one spatial dimension is completely coherently controlled. 相似文献
92.
93.
McCulloch I Heeney M Bailey C Genevicius K Macdonald I Shkunov M Sparrowe D Tierney S Wagner R Zhang W Chabinyc ML Kline RJ McGehee MD Toney MF 《Nature materials》2006,5(4):328-333
Organic semiconductors that can be fabricated by simple processing techniques and possess excellent electrical performance, are key requirements in the progress of organic electronics. Both high semiconductor charge-carrier mobility, optimized through understanding and control of the semiconductor microstructure, and stability of the semiconductor to ambient electrochemical oxidative processes are required. We report on new semiconducting liquid-crystalline thieno[3,2-b ]thiophene polymers, the enhancement in charge-carrier mobility achieved through highly organized morphology from processing in the mesophase, and the effects of exposure to both ambient and low-humidity air on the performance of transistor devices. Relatively large crystalline domain sizes on the length scale of lithographically accessible channel lengths ( approximately 200 nm) were exhibited in thin films, thus offering the potential for fabrication of single-crystal polymer transistors. Good transistor stability under static storage and operation in a low-humidity air environment was demonstrated, with charge-carrier field-effect mobilities of 0.2-0.6 cm(2) V(-1) s(-1) achieved under nitrogen. 相似文献
94.
Labib M Zamay AS Muharemagic D Chechik AV Bell JC Berezovski MV 《Analytical chemistry》2012,84(4):1813-1816
The development of aptamer-based viability impedimetric sensor for viruses (AptaVISens-V) is presented. Highly specific DNA aptamers to intact vaccinia virus were selected using cell-SELEX technique and integrated into impedimetric sensors via self-assembly onto a gold microelectrode. Remarkably, this aptasensor is highly selective and can successfully detect viable vaccinia virus particles (down to 60 virions in a microliter) and distinguish them from nonviable viruses in a label-free electrochemical assay format. It also opens a new venue for the development of a variety of viability sensors for detection of many microorganisms and spores. 相似文献
95.
大塑性变形纳米结构Al-Mg合金中的形变缺陷和电子辐照效应 总被引:1,自引:0,他引:1
为澄清大塑性变形纳米结构Al-Mg合金中形变缺陷形成的本质,采用高分辨透射电子显微镜(HRTEM)研究电子辐照对高压扭转合金中面缺陷形成的影响。结果表明:对已有高密度面缺陷的HRTEM图像,经电子束照射一段时间后,这些面缺陷会完全消失;而在没有缺陷的HRTEM图像区域进行电子辐照,即使电子束的照射提高到足以在该区域击出孔洞,整个过程均未观察到任何晶格缺陷。因此,高压扭转合金中的面缺陷主要来源于极度的塑性变形,而与HRTEM观察过程中的电子辐照效应无关。 相似文献
96.
A predictive model for heat induced shape deviations would facilitate the optimization of dry milling strategies. Results from milling experiments aiming at a physically based regression model for the heat flux distribution along the contact arc are presented. The contact arc was discretised by varying the width of cut on four levels for each combination of cutting speed, feed speed, and depth of cut. Heat fluxes to the workpiece were iteratively determined in an inverse procedure. Heat partitioning not only depends on the thermal number as in orthogonal cutting but also on the feed speed and the depth of cut. 相似文献
97.
Goryachev M Galliou S Abbe P Bourgeois PY Grop S Dubois B 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2012,59(1):21-29
The phase noise of a quartz crystal resonator working at liquid helium temperatures is studied. Measurement methods and the device environment are explained. The phase noise is measured for different resonance modes, excitation levels, amount of operating time, device orientations in relation to the cryocooler vibration axis, and temperatures. Stability limits of a frequency source based on such devices are evaluated in the present measurement conditions. The sources of phase flicker and white noises are identified. Finally, the results are compared with previous works. 相似文献
98.
Kokhanchik LS Borodin MV Burimov NI Shandarov SM Shcherbina VV Volk TR 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2012,59(6):1076-1084
We report the results of fabrication and investigations of surface periodic domain structures created by a set of quasi-point e-beam irradiations both on the Y- and X-cuts of LiNbO(3), and on Ti:LiNbO(3) and Zn:LiNbO(3) planar waveguides. Domain gratings with spatial periods from 4.75 to 7.25 μm were formed by a 25-keV e-beam. Doses from 500 to 2000 μC/cm(2) were used for different structures to estimate optimal fabrication conditions. The investigations allowed the visualization of the formed surface domain structures, estimation of their uniformity, and determination of waveguide generation of the second optical harmonic. The surface structures can be used in optical devices for the realization of quasi-phase-matched frequency conversion, which includes the creation of compact radiation sources based on waveguides. 相似文献
99.
Maksyutenko P Grechko M Rizzo TR Boyarkin OV 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2012,370(1968):2710-2727
We summarize here our experimental studies of the high rovibrational energy levels of water. The use of double-resonance vibrational overtone excitation followed by energy-selective photofragmentation and laser-induced fluorescence detection of OH fragments allowed us to measure previously inaccessible rovibrational energies above the seventh OH-stretch overtone. Extension of the experimental approach to triple-resonance excitation provides access to rovibrational levels via transitions with significant transition dipole moments (mainly OH-stretch overtones) up to the dissociation threshold of the O-H bond. A collisionally assisted excitation scheme enables us to probe vibrations that are not readily accessible via pure laser excitation. Observation of the continuous absorption onset yields a precise value for the O-H bond dissociation threshold, 41?145.94 ± 0.15?cm(-1). Finally, we detect long-lived resonances as sharp peaks in spectra above the dissociation threshold. 相似文献
100.
Ruslan Z. Valiev Maxim Yu. Murashkin Askar Kilmametov Boris Straumal Nguyen Q. Chinh Terence G. Langdon 《Journal of Materials Science》2010,45(17):4718-4724
Processing by severe plastic deformation (SPD) typically increases the strength of metals and alloys drastically by decreasing
their grain size into the submicrometer or nanometer range but the ductility of such materials remains typically low. This
report describes the first demonstration that it is possible to increase the room temperature ductility of aluminum-based
alloys processed by SPD and to attain elongations to failure of >150% while retaining the enhanced strength. This unique combination
of properties is due to the occurrence of grain boundary sliding at room temperature. The sliding was obviously achieved by
introducing a grain boundary wetting of the aluminum/aluminum grain boundaries. 相似文献