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241.
Y. L. Jia X. Geng H. Sun Y. Luo 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,83(4):451-455
We have studied the exciton effects in armchair graphene nanoribbons systematically,
using the nonorthogonal tight-binding model supplement by the long-range Coulomb
interactions. It is found from our calculations that the excitation energies, the exciton
binding energies and the exciton wave function sizes of
the E
11 and E
22 excitons all
exhibit oscillation as a function of the ribbon width. And there is a phase shift
of π between the oscillation of the E
11
and E
22 excitons. 相似文献
242.
243.
Influence of reaction gas flows on the properties of SiGe:H thin film prepared by plasma assisted
reactive thermal chemical vapour deposition 总被引:1,自引:0,他引:1
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A new preparing technology, very high frequency plasma assisted reactive thermal chemical vapour deposition (VHFPA-RTCVD), is introduced to prepare SiGe:H thin films on substrate kept at a lower temperature. In the previous work, reactive thermal chemical vapour deposition (I~TCVD) technology was successfully used to prepare SiGe:H thin films, but the temperature of the substrate needed to exceed 400℃. In this work, very high frequency plasma method is used to assist RTCVD technology in reducing the temperature of substrate by largely enhancing the temperature of reacting gases on the surface of the substrate. The growth rate, structural properties, surface morphology, photo- conductivity and dark-conductivity of SiGe:H thin films prepared by this new technology are investigated for films with different germanium concentrations, and the experimental results are discussed. 相似文献
244.
1 IntroductionIn this paper we study the blow--up of positive solutions as A - 0+ fOr thefOllowing boundary value problem of the weighted pLaplacian on the unit ballcenter at the origin B = B1(0) C Rn:where cr5 u > fi --p > --n and p* = p(n + a)/(fi +n --p) is the critical exponentof the embedding Wl"(fl, lxtpdx) - Lp*(fl, lxl"dx) (see, for example, [6]).When u is radially symmetric, y(r) = u(x), fOr r = lxl, satisfieswhere the new exponents cr, g, p and p* satisfyThe existence and non-exi… 相似文献
245.
G.L. Tu C.Y. Mei Q.G. Zhou Y.X. Cheng Y.H. Geng L.X. Wang D.G. Ma X.B. Jing F.S. Wang 《Advanced functional materials》2006,16(1):101-106
Light‐emitting diodes exhibiting efficient pure‐white‐light electroluminescence have been successfully developed by using a single polymer: polyfluorene derivatives with 1,8‐naphthalimide chromophores chemically doped onto the polyfluorene backbones. By adjusting the emission wavelength of the 1,8‐naphthalimide components and optimizing the relative content of 1,8‐naphthalimide derivatives in the resulting polymers, white‐light electroluminescence from a single polymer, as opposed to a polymer blend, has been obtained in a device with a configuration of indium tin oxide/poly(3,4‐ethylenedioxythiophene)(50 nm)/polymer(80 nm)/Ca(10 nm)/Al(100 nm). The device exhibits Commission Internationale de l'Eclairage coordinates of (0.32,0.36), a maximum brightness of 11 900 cd m–2, a current efficiency of 3.8 cd A–1, a power efficiency of 2.0 lm W–1, an external quantum efficiency of 1.50 %, and quite stable color coordinates at different driving voltages, even at high luminances of over 5000 cd m–2. 相似文献
246.
247.
Geng NF Goh PG Johnson BF Martin CM Shephard DS Zhou W 《Angewandte Chemie (International ed. in English)》2000,39(9):1661-1664
248.
Geng W Cosman P Berry CC Feng Z Schafer WR 《IEEE transactions on bio-medical engineering》2004,51(10):1811-1820
This paper presents a method for automatic tracking of the head, tail, and entire body movement of the nematode Caenorhabditis elegans (C. elegans) using computer vision and digital image analysis techniques. The characteristics of the worm's movement, posture and texture information were extracted from a 5-min image sequence. A Random Forests classifier was then used to identify the worm type, and the features that best describe the data. A total of 1597 individual worm video sequences, representing wild type and 15 different mutant types, were analyzed. The average correct classification ratio, measured by out-of-bag (OOB) error rate, was 90.9%. The features that have most discrimination ability were also studied. The algorithm developed will be an essential part of a completely automated C. elegans tracking and identification system. 相似文献
249.
Signal changes can be detected by proton density-weighted functional imaging in both the brain and the spinal cord. These are attributed to changes in extravascular water proton (signal enhancement by extravascular protons) density during neuronal activation. In this study, we used this technique to detect correlations between acupoint stimulation and neural activity in the spinal cord. Stimulation of acupoints associated with treatment of sensorimotor deficits (LI4 and LI11) was performed on 11 volunteers. During stimulation, 8 of the 11 subjects had consistent functional activations in C6/C7. A bilateral activation pattern was common. Our findings show that acupoint stimulation modulates activity in the spinal cord. 相似文献
250.
Deeply penetrating photoacoustic tomography in biological tissues enhanced with an optical contrast agent 总被引:3,自引:0,他引:3
Photoacoustic tomography (PAT) in a circular scanning configuration was developed to image deeply embedded optical heterogeneity in biological tissues. While the optical penetration was maximized with near-infrared laser pulses of 800-nm wavelength, the optical contrast was enhanced by Indocyanine Green (ICG) dye whose absorption peak matched the laser wavelength. This optimized PAT was able to image objects embedded at depths of as much as 5.2 cm, 6.2 times the 1/e optical penetration depth, in chicken breast muscle at a resolution of <780 microm and a sensitivity of <7 pmol of ICG in blood. The resolution was found to deteriorate slowly with increasing imaging depth. The effects of detection bandwidth on the quality of images acquired simultaneously by four different ultrasonic transducers are described. 相似文献