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171.
Yongbo Bian Jin Guo Changzheng Gao Chunguang Li Hong Li Jia Wang Bin Cui Xiaofeng He Chao Li Na Li Guoqiang Li Qiang Zhang Xueqiang Zhang Jibao Meng Yusheng He 《Physica C: Superconductivity and its Applications》2010,470(15-16):617-621
This paper presents a miniaturized high performance high temperature superconducting (HTS) microwave receiver front-end subsystem, which uses a mini stirling cryocooler to cool a high selective HTS filter and a low noise amplifier (LNA). The HTS filter was miniaturized by using specially designed compact resonators and fabricating with double-sided YBCO films on LAO substrate which has a relatively high permittivity. The LNA was specially designed to work at cryogenic temperature with noise figure of 0.27 dB at 71 K. The mini cryocooler, which is widely used in infrared detectors, has a smaller size (60 mm × 80 mm × 100 mm) and a lighter weight (340 g) than the stirling cryocoolers commonly used in other HTS filter subsystem. The whole front-end subsystem, including a HTS filter, a LNA, a cryocooler and the vacuum chamber, has a size of only φ120 mm × 175 mm and a weight of only 3.3 kg. The microwave devices inside the subsystem are working at 71.8 K with a consumed cooling power of 0.325 W. The center frequency of this subsystem is 925.2 MHz and the bandwidth is 2.7 MHz (which is a fractional bandwidth of 0.2%), with the gain of 19.75 dB at center frequency and the return loss better than ?18.11 dB in the pass band. The stop band rejection is more than 60 dB and the skirt slope is exceeding 120 dB MHz?1. The noise figure of this subsystem is less than 0.8 dB. This front-end subsystem can be used in radars and communication systems conveniently due to it’s compact size and light weight. 相似文献
172.
Weiwei Liang Feng Chen Hao Bian Qing Yang Xianhua Wang Jinhai Si Xun Hou 《Optics Communications》2010,283(11):2385-2389
Periodic surface nanostructures induced by femtosecond laser pulses on polycrystalline ZnO are presented. By translating the sample line-by-line under appropriate irradiation conditions, grating-like nanostructures with an average period of 160 nm are fabricated. The dependence of surface morphologies on the processing parameters, such as laser fluence, pulse number and laser polarization, are studied by scanning electronic microscope (SEM). In addition, photoluminescence (PL) analysis at room-temperature indicates that the PL intensity of the irradiated area increases significantly compared with the un-irradiated area. Using femtosecond laser pulses irradiation to fabricate periodic surface nanostructures on polycrystalline ZnO is efficient, simple and low cost, which shows great potential applications in ZnO-based optoelectronic devices. 相似文献
173.
Ablikim M Achasov MN An L An Q An ZH Bai JZ Baldini R Ban Y Becker J Berger N Bertani M Bian JM Boyko I Briere RA Bytev V Cai X Cao GF Cao XX Chang JF Chelkov G Chen G Chen HS Chen JC Chen ML Chen SJ Chen Y Chen YB Cheng HP Chu YP Cronin-Hennessy D Dai HL Dai JP Dedovich D Deng ZY Denysenko I Destefanis M Ding Y Dong LY Dong MY Du SX Duan MY Fan RR Fang J Fang SS Feldbauer F Feng CQ Fu CD Fu JL Gao Y Geng C Goetzen K Gong WX Greco M Grishin S Gu MH Gu YT Guan YH Guo AQ Guo LB Guo YP Hao XQ 《Physical review letters》2010,105(26):261801
The decays ψ'→γπ(0), γη and γη' are studied using data collected with the BESIII detector at the BEPCII e(+)e(-) collider. The processes ψ'→γπ(0) and ψ'→γη are observed for the first time with signal significances of 4.6σ and 4.3σ, respectively. The branching fractions are determined to be B(ψ'→γπ(0))=(1.58±0.40±0.13)×10(-6), B(ψ'→γη)=(1.38±0.48±0.09)×10(-6), and B(ψ'→γη')=(126±3±8)×10(-6), where the first errors are statistical and the second ones systematic. 相似文献
174.
Yi Fu Baojun Bian Jizhou Zhang Dirk Linowski 《Journal of Applied Analysis & Computation》2018,8(4):1122-1142
In this paper, we develop an optimal execution strategy for employee stock options by means of the fluid model, in which a voluntary turnover is considered. We show that the value function is the viscosity solution of the Hamilton-Jacobi-Bellman variational inequality and prove the uniqueness of the viscosity solution. Finally, we present numerical illustrative examples and numerical solutions of optimal strategies which are computed by the finite difference method. 相似文献
175.
A selective reduction method of an electronically deficient imine in the presence of ketone was developed by employing Et(2)Zn and 5 mol % of Ni(acac)(2). The method was applied in the reduction of S(S)-tert-butanesulfinyl ketimines 1 to afford amines 2 in 23-92% yields and 73:27 to 98:2 diastereoselectivities. A plausible mechanism was proposed on the basis of an NMR study. 相似文献
176.
Ablikim M Bai JZ Ban Y Bian JG Cai X Chang JF Chen HF Chen HS Chen HX Chen JC Chen J Chen J Chen ML Chen YB Chi SP Chu YP Cui XZ Dai HL Dai YS Deng ZY Dong LY Du SX Du ZZ Fang J Fang SS Fu CD Fu HY Gao CS Gao YN Gong MY Gong WX Gu SD Guo YN Guo YQ Guo ZJ Harris FA He KL He M He X Heng YK Hu HM Hu T Huang GS Huang L Huang XP Ji XB Jia QY Jiang CH Jiang XS Jin DP Jin S Jin Y Lai YF Li F Li G Li HB Li HH Li J Li JC Li QJ Li RB Li RY Li SM Li WG Li XL Li XQ Li XS Liang YF Liao HB Liu CX Liu F Liu F 《Physical review letters》2006,97(6):062001
The decay J/psi-->NNpi provides an effective isospin 1/2 filter for the piN system due to isospin conservation. Using 58x10(6) J/psi decays collected with the Beijing Electromagnetic Spectrometer at the Beijing Electron Positron Collider, more than 100 thousand J/psi-->ppi-n+c.c. events are obtained. Besides the two well-known N* peaks at around 1500 MeV/c2 and 1670 MeV/c2, there are two new, clear N* peaks in the ppi invariant mass spectrum around 1360 MeV/c2 and 2030 MeV/c2 with statistical significance of 11sigma and 13sigma, respectively. We identify these as the first direct observation of the N*(1440) peak and a long-sought missing N* peak above 2 GeV/c2 in the piN invariant mass spectrum. 相似文献
177.
采用基于密度泛函理论的第一性原理赝势法对Ag-N共掺杂ZnO体 系以及间隙N和间隙H掺杂p型ZnO: (Ag, N)体系的缺陷形成能和离化能进行了研究. 结果表明, 在AgZn和NO所形成的众多受主复合体中, AgZn-NO受主对不仅具有较低的缺陷形成能同时其离化能也相对较小, 因此, AgZn-NO受主对的形成是Ag-N共掺ZnO体系实现p型导电的主要原因. 研究发现, 当ZnO: (Ag, N)体系有额外间隙N原子存在时, AgZn-NO受主对容易与Ni形成AgZn-(N2)m O施主型缺陷, 该施主缺陷的形成降低了Ag-N共掺ZnO的掺杂效率因而不利于p型导电. 当间隙H引入到ZnO: (Ag, N)体系时, Hi易与AgZn-NO受主对形成 受主-施主-受主复合结构(AgZn-Hi-NO), 此复合体的形成不仅提高了AgZn-NO受主对在ZnO中的固溶度, 同时还能使其受主能级变得更浅而有利于p型导电. 因此, H辅助Ag-N共掺ZnO可能是一种有效的p型掺杂手段.
关键词:
p型ZnO
缺陷形成能
受主离化能
第一性原理 相似文献
178.
Chongxin Yin Min Wang Qingzhi Ma Huiyang Bian Hao Ren Hongqi Dai Jinlan Cheng 《Molecules (Basel, Switzerland)》2021,26(14)
Rice straw hydrotropic lignin was extracted from p-Toluene sulfonic acid (p-TsOH) fractionation with a different combined delignification factor (CDF). Hydrotropic lignin characterization was systematically investigated, and alkaline lignin was also studied for the contrast. Results showed that the hydrotropic rice straw lignin particle was in nanometer scopes. Compared with alkaline lignin, the hydrotropic lignin had greater molecular weight. NMR analysis showed that β-aryl ether linkage was well preserved at low severities, and the unsaturation in the side chain of hydrotropic lignin was high. H units and G units were preferentially degraded and subsequently condensed at high severity. High severity also resulted in the cleavage of part β-aryl ether linkage. 31P-NMR showed the decrease in aliphatic hydroxyl groups and the increasing carboxyl group content at high severity. The maximum weight loss temperature of the hydrotropic lignin was in the range of 330–350 °C, higher than the alkaline lignin, and the glass conversion temperature (Tg) of the hydrotropic lignin was in the range of 107–125 °C, lower than that of the alkaline lignin. The hydrotropic lignin has high β-aryl ether linkage content, high activity, nanoscale particle size, and low Tg, which is beneficial for its further valorization. 相似文献
179.
Shuwei Wan Xingming Bian Lan Chen Deming Yu Liming Wang Zhicheng Guan 《Journal of Electrostatics》2013,71(4):778-780
The effect of electrostatic discharge on safe distance determination for 500 kV ac transmission line's helicopter inspection is investigated. Potential difference exists while helicopter is near the power transmission line, which is harmful to the inspection persons. The electric field in the helicopter cabin is calculated when it is near the power line. The result indicates that the potential difference becomes higher with the decrease of the distance between the helicopter and transmission line. Considering the discharge energy and the guarantee of the persons' safety, the safe distance for 500 kV ac transmission lines is determined as d ≥ 15 m. 相似文献
180.
AbstractThe interaction of pioglitazone hydrochloride bound to tryptophan residues and tyrosine residues in bovine transferrin was investigated using synchronous fluorescence spectroscopy at various temperatures (298, 310, and 318?K). From binding constants and thermodynamic parameters, it was shown that 1:1 stable compound was formed by the electrostatic force interaction of pioglitazone hydrochloride bound to tryptophan residues and tyrosine residues in bovine transferrin. The extent of binding between pioglitazone hydrochloride and tryptophan residues in bovine transferrin was more than that between pioglitazone hydrochloride and tyrosine residues in bovine transferrin. At 310?K, the fluorescence quenching ratio number of tyrosine residues and tryptophan residues in bovine transferrin were 47.52% and 54.19%, respectively, which indicated that the fluorescence contribution of tryptophan residues was greater. At 310?K, pioglitazone hydrochloride-tyrosine residues(in bovine transferrin) binding rate were 55.60–73.82%, and the combined model was W?=??0.0315R2???0.1520R?+?0.7385. The value of Hill’s coefficients was greater than 1, which suggested that there was a positive cooperativity between pioglitazone hydrochloride and subsequent ligands. The results of molecular docking were consistent with that of experimental calculation. 相似文献