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991.
Modal interferometer based on tapering single-mode-multimode-single-mode fiber structure by hydrogen flame 总被引:1,自引:0,他引:1
A modal interferometer is experimentally demonstrated based on tapering a single-mode-multimode-singlemode (SMS) fiber structure heated by hydrogen flame.The interference fringe begins to form when tapering length is 19.8 mm,and becomes regular and clear when the tapering length is longer and the tapered waist diameter is smaller.Annealing process is undertaken to achieve a high extension ratio of approximately 17 dB with free spectral range of 1.5 nm when the tapering length is 33 mm and the tapered waist diameter is approximately 5μm.The temperature and axial strain dependences of the tapered SMS structure are characterized,and the measured temperature and strain coefficients are +7 pm/℃and -9.536 pm/με, respectively. 相似文献
992.
Thampy V Kang J Rodriguez-Rivera JA Bao W Savici AT Hu J Liu TJ Qian B Fobes D Mao ZQ Fu CB Chen WC Ye Q Erwin RW Gentile TR Tesanovic Z Broholm C 《Physical review letters》2012,108(10):107002
Using polarized and unpolarized neutron scattering, we show that interstitial Fe in superconducting Fe(1+y)Te(1-x)Se(x) induces a magnetic Friedel-like oscillation that diffracts at Q⊥=(1/2 0) and involves >50 neighboring Fe sites. The interstitial >2μ(B) moment is surrounded by compensating ferromagnetic four-spin clusters that may seed double stripe ordering in Fe(1+y)Te. A semimetallic five-band model with (1/2 1/2) Fermi surface nesting and fourfold symmetric superexchange between interstitial Fe and two in-plane nearest neighbors largely accounts for the observed diffraction. 相似文献
993.
CO adsorption on the Ge(100) surface has been investigated using a slab model with density functional theory implemented in SIESTA. CO was found to be exclusively adsorbed on the asymmetric dimer with C attaching on the lower Ge dimer atom. The adsorption process is barrierless. The calculated adsorption energy and vibration frequencies are comparable to previous experimental results. The crystal orbital Hamilton analysis showed that the bonding between Ge and CO is mainly attributable to the Ge 4pz orbital overlapping with C 2 s, or with CO molecular orbitals 3σ and 4σ. The repulsive energy between adsorbed CO molecules is less than 1 kcal/mol. The diffusion barrier of CO on the Ge(100) surface is about 14 kcal/mol. 相似文献
994.
不同于传统的非制冷红外成像技术,提出了基于微电子机械系统(MEMS)的新概念光学读出非制冷红外成像技术。它的光学读出系统基于空间刀口滤波原理,具有高灵敏度、高分辨率和高抗震性等优点,但同时也受到了反光板的弯曲变形、粗糙度等复杂因素的影响。在大量实验数据的基础上,利用夫琅禾费近场衍射理论,建立了复杂因素下光学灵敏度的理论分析模型,详细分析了刀口滤波位置、反光板的长度、曲率半径、粗糙度、LED光源的强度以及扩展宽度等对光学灵敏度的影响,并提出了通过极限操作使系统的光学灵敏度最大化的光学优化方法。 相似文献
995.
Xingyu Mao Zhijian KeWeidong Zou Qiubao LinZhijie Qin Yan Wu 《Journal of magnetism and magnetic materials》2012,324(4):389-393
The dynamic magnetization processes of nanocrystalline Fe80Ge3Nb10B7 alloys after annealing at different temperatures are studied through the permeability spectroscopy. Three steps of crystallization are found when amorphous Fe80Ge3Nb10B7 alloys are heated from 300to 1200 K. The dominant magnetization process varies with different annealing temperatures. Domain wall bulging is the main magnetization mechanism under weak applied field. When the applied field exceeds pinning field Hp, the depinning-involved domain wall displacement occurs. Different annealing temperature results in different Hp. The lower value of μ′ and high relaxation frequency after heating at 923 and 973 K are due to the strengthened domain wall pinning and the increase of magnetocrystalline anisotropy. 相似文献
996.
p-Sulfonated calix[6]arene modified graphene has been firstly synthesized and provided as a 'turn on' probe for L-carnitine through monitoring the fluorescence signal both in vitro and in living cells. 相似文献
997.
998.
PET/silica nanocomposite fibers of high quality were fabricated from electrospinning by choosing appropriate surface modification of inorganic fillers, solution properties, and processing conditions. The existence of an immobilized layer around silane-modified silica particles in PET fibers was verified by Fourier transform infrared spectroscopy, the results of which confirm previous thermal analysis studies. The influence of silica particles on the crystal growth during isothermal crystallization as well as the phase structure of the crystallized nanocomposite fibers were examined using differential scanning calorimetry. The PET crystallization rate increases significantly with increasing silica content, which indicates that the silica nanoparticles act as an efficient nucleating agent to facilitate PET crystallization. Using Avrami analysis, for the first time, preferred 1-D crystal growth was confirmed for geometrically confined nanocomposite fibers. Addition of silica particles makes the crystal growth more likely to occur in a 1-D manner. 相似文献
999.
Jia-jia Ji Hui Sun Xiang-yu Mao Wei Wang Xiao-bing Chen 《Journal of Sol-Gel Science and Technology》2012,61(2):328-331
The Bi5FeTi3O15 (BFTO) films of layered structure have been fabricated on Pt/Ti/SiO2/Si substrates by the sol–gel method. The thermal decomposition behaviors of precursor powder were examined using thermo-gravimetric
and differential scanning calorimeters analysis. The optimal heat treatment process for BFTO films were determined to be low-temperature
drying at 200 °C for 4 min and high-temperature drying at 350 °C for 5 min followed by annealing at 740 °C for 60 min, which
led to the formation of compact films with uniform grains of ~300 nm. The structural, surface topography, ferroelectric and
magnetic properties of the films were investigated. The remnant polarization (2P
r) of BFTO thin films under an applied electric field of ~550 kV/cm are determined to be 67.5 μC/cm2
. Meanwhile, the weak ferromagnetic properties of the BFTO films were observed at room temperature. 相似文献
1000.
A highly efficient catalyst system assembled from enantiomerically pure diaminocyclohexane and Ni(OAc)(2) is, for the first time, used to catalyze the cascade Michael-Henry reaction of various diones and substituted nitroalkenes. A series of polyfunctionalized bicyclo[3.2.1]octane derivatives containing four stereogenic centers are prepared with excellent enantioselectivities (up to >99% ee) and diastereoselectivities (up to 50 : 1 dr) with high yields. In addition, via this chiral diamine-Ni(OAc)(2) catalyst system, the base-induced epimerization leading to the decrease of stereoselectivity can be prevented. 相似文献