排序方式: 共有136条查询结果,搜索用时 31 毫秒
1.
Jun Dai Liqiang Xu Zengli Fang Daopeng Sheng Qingfeng Guo Zeyu Ren Kang Wang Yitai Qian 《Chemical physics letters》2007,440(4-6):253-258
Straight boron nitride nanotubes (BNNTs) with pure hexagonal phase were conveniently prepared by heating the mixture of Mg(BO2)2 · H2O, NH4Cl, NaN3 and Mg powder in an autoclave at 600 °C for 20–60 h. These BNNTs had diameters mainly ranging 30–300 nm and lengths up to 5 μm, and a majority of them had at least one closed end. Besides the traditional end tips, additional cone-like tips were frequently found to be attached on the BNNTs. The effects of temperature, reactants and the possible mechanism of the catalytic formation of the BNNTs are discussed. 相似文献
2.
We demonstrated a 3D laser imaging system at 1550 nm with a 1.5-GHz sine-wave gated Geiger-mode InGaAs/InP avalanche photodiode (APD). An optical fiber bundle with 100 individual fiber outputs was implemented at the focal plane of the telescope, providing a 2.5-mrad imaging view. The system used single-pixel near-infrared single-photon detector to measure photons at fiber outputs instead of a photon counting array. The 1.5-GHz gated Geiger-mode InGaAs/InP APD with a timing jitter of 290 ps was operated in quasi-continuous mode with detection efficiency of ∼4.3%. We achieved higher than 6-cm surface-to-surface resolution at single-photon level, showing a potential of low-energy and eye-safe laser imaging system for long-distance measurements. 相似文献
4.
Dongliang Tang Changtao Wang Zeyu Zhao Yanqin Wang Mingbo Pu Xiong Li Ping Gao Xiangang Luo 《Laser \u0026amp; Photonics Reviews》2015,9(6):713-719
Conventional optics is diffraction limited due to the cutoff of spatial frequency components, and evanescent waves allow subdiffraction optics at the cost of complex near‐field manipulation. Recently, optical superoscillatory phenomena were employed to realize superresolution lenses in the far field, but suffering from very narrow working wavelength band due to the fragility of the superoscillatory light field. Here, an ultrabroadband superoscillatory lens (UBSOL) is proposed and realized by utilizing the metasurface‐assisted law of refraction and reflection in arrayed nanorectangular apertures with variant orientations. The ultrabroadband feature mainly arises from the nearly dispersionless phase profile of transmitted light through the UBSOL for opposite circulation polarization with respect to the incident light. It is demonstrated in experiments that subdiffraction light focusing behavior holds well with nearly unchanged focal patterns for wavelengths spanning across visible and near‐infrared light. This method is believed to find promising applications in superresolution microscopes or telescopes, high‐density optical data storage, etc.
5.
Siyuan Li Weidong Zhang Qiang Wu Lei Fan Xinyang Wang Xiao Wang Zeyu Shen Yi He Yingying Lu 《Angewandte Chemie (International ed. in English)》2020,59(35):14935-14941
A rechargeable Li metal anode coupled with a high‐voltage cathode is a promising approach to high‐energy‐density batteries exceeding 300 Wh kg?1. Reported here is an advanced dual‐additive electrolyte containing a unique solvation structure and it comprises a tris(pentafluorophenyl)borane additive and LiNO3 in a carbonate‐based electrolyte. This system generates a robust outer Li2O solid electrolyte interface and F‐ and B‐containing conformal cathode electrolyte interphase. The resulting stable ion transport kinetics enables excellent cycling of Li/LiNi0.8Mn0.1Co0.1O2 for 140 cycles with 80 % capacity retention under highly challenging conditions (≈295.1 Wh kg?1 at cell‐level). The electrolyte also exhibits high cycling stability for a 4.6 V LiCoO2 (160 cycles with 89.8 % capacity retention) cathode and 4.95 V LiNi0.5Mn1.5O4 cathode. 相似文献
6.
Nonlinear Dynamics - During the process of spacecraft launch, the extreme vibration environment is the major influence factor that induces the failure of the mission. Inspired by the smooth motions... 相似文献
7.
Xiaoyong Chen Zeyu Zhang Jiajie Wu Jiale Wang Aolong Gao 《Particle & Particle Systems Characterization》2021,38(7):2100076
Red fluorescent carbon dots (R-CDs) are special desirable for biochemical analysis due to good biological compatibility and deep penetration; however, they remain as bottlenecks due to difficulties in expanding the sp2 domain, especially those are fused from rigid polycyclic conjugated molecules (RPCMs) with heteroatom substituents due to huge steric hindrance and heteroatom blockage toward graphic lattice. Here, an RPCM with heteroatom substituents, 1,5-diamino-4,8-dihydroxyanthraquinone (DDAQ), based self-doped R-CDs with PL emission at 635 nm is reported. Further investigations reveal that the expanding, hybrid sp2 domain with indanthrone tannin structure from DDAQ is mainly responsible for the obtained red fluorescence of R-CDs. Taking advantage of optical properties, R-CDs are considered to construct a colorimetric/fluorescent dual mode sensing array for quantifying trace levels of Fe3+ and glyphosate based on the static quenching, and a biomarker for cell imaging. The CD-based sensors exhibit outstanding recovery, high selectivity, and sensitivity, also facilitated dual-mode detection with the naked-eye. The R-CDs have low cytotoxicity, good cell membrane penetration for rapid cell entry, and high resolution, demonstrating their potential for biolabeling and bioanalytic applications. 相似文献
8.
Pt/Eu2O3-CeO2 materials with different Eu concentrations were prepared and applied to toluene destruction, and the remarkable promotion impact of EuOx on Pt/CeO2 can be observed. The characterization results reveal that the presence of EuOx significantly enhances the redox property, lattice O concentration, and Ce3+ ratio of the Pt/CeO2 material, which facilitates the dispersion and activity of Pt active sites and thus accelerates the decomposition process of toluene. Among all catalysts, a sample with an Eu content of 2.5 at.% (Pt/EC-2.5) possesses the best catalytic activity with 0.09 vol% of toluene completely destructed at 200 °C under a relatively high GHSV of 50000 h?1. The possible reaction pathway and mechanism of toluene combustion over Pt/Eu2O3-CeO2 samples are presented according to in-situ DRIFTS, which confirms that the toluene oxidation process obeys the Mars-van Krevelen mechanism with aldehydes and ketones as primary organic intermediates. 相似文献
9.
Huiliang Xu Zeyu Zhao Yueguang Lv Chunlei Du Xiangang Luo 《International Journal of Infrared and Millimeter Waves》2008,29(5):493-498
A high directive planar antenna made from a metamaterial superstrate and an electromagnetic band-gap (EBG) substrate has been
investigated. A patch antenna surrounded with EBG structures is used as the radiation source. The CST Microwave Studio is
used for the simulation. The results show that the gain of the antenna with metamaterial is 21.6 dB at the operating frequency
of 14.6 GHz. Compared with the patch feed with the same aperture size but without the metamaterial superstrate, the performance
of the antenna is improved obviously and the gain increases about 12.4 dB. 相似文献
10.
Journal of Visualization - Interpreting the decision-making of black boxes in machine learning becomes urgent nowadays due to their lack of transparency. One effective way to interpret these models... 相似文献