硫酸软骨素A对草酸钙晶体生长和聚集的影响

用体外模拟方法研究了硫酸软骨素 A(简称 C4S)对草酸钙晶体矿化热力学的影响 ,并对纯水体系和 C4S- H2 O体系中形成的草酸钙晶体进行了物相分析与形貌观察。发现 C4S不但在热力学过程中有利于提高溶液中 Ca2 + 存在的浓度 ,而且能诱导一水草酸钙 ( COM)晶体的 ( 1 0 1 )晶面优先生长 ,并抑制 COM的二维生长和聚集。     

Spectroscopic properties of vacancies and trap levels in Lu3Al5O12：Ce^3＋ crystals

In order to study the spectroscopic properties of vacancies and trap levels in Lu₃Al₅O₁₂:Ce³⁺ (LuAG:Ce³⁺) crystal, the <111>-oriented LuAG:Ce³⁺ crystal grown in pure nitrogen atmosphere by Czochralski method was annealed in oxidizing atmosphere (air) and reducing atmosphere (H₂+N₂), respectively. The excitation and emission spectra of LuAG:Ce³⁺ crystal after different thermal annealing treatments were measured in the temperature range of 8?450 K, and the thermally stimulated luminescence curves of LuAG:Ce³⁺ crystal were characterized. It is found that the oxygen vacancies in LuAG:Ce³⁺ crystal are effectively eliminated through the annealing treatment in air and four trap levels are observed in as-grown LuAG:Ce³⁺ crystal with temperature position peaking at 110, 210, 325 and 475 °C, respectively.     

Effects of Annealing Treatments on Luminescence and Scintillation Properties of Ce：Lu3 Al5 O12 Crystal Grown by Czochralski Method

Lu3Al5O12 single crystals grown in pure N2 atmosphere by Czochralski method were annealed in oxidizing atmosphere （air）and reducing atmosphere （H2 ＋ N2）, respectively. Effects of annealing treatments on luminescence and scintillation properties of the crystals were investigated. The crystal annealed in air showed the highest luminescence intensity under blue light or vacuum ultraviolet excitation in comparison with that annealed in reducing flux or the as-grown crystal. Under X-ray excitation, crystal annealed in reducing atmosphere had the lowest light yield, and crystal annealed in air had the fastest decay time under ^137Cs 662 keV γ-ray excitation. Different annealing treatments resulted in different luminescence and scintillation properties, which might related with oxygen vacancies or defect existing in the crystals.     

基于压电晶体的声波激励小型化低频天线技术研究

水下信息实时传输的需求与日俱增,水声通信和光通信等传统通信手段在传输安全性与稳定性方面具有先天难以弥补的劣势,且在传输速率方面难以形成突破,因此亟待对新技术进行研究。为解决此问题,近年一些学者提出一种新机理、新材料和新工艺的小型化天线,有望实现低频天线在尺寸和性能上的跨越,实现水下通信技术的变革。该文对此类声波激励小型化天线进行研究。首先阐述并建立了天线辐射机理及理论模型,分析了不同材料参数对天线性能的影响;然后根据模型参数设计加工了基于铌酸锂(LiNbO₃)晶体的压电型声波激励天线样机,实验结果表明在40.83 kHz谐振频率处,与同尺寸单极子天线相比,其接收电压峰值为后者的22倍,辐射效率为400多倍;最后对天线进行了方位测试和辐射效率计算。上述结果表明：基于压电晶体的声波激励天线技术在低频段小型化、机动化水下无线通信设备的应用中具有巨大潜力。