敏化光波长对(Fe,Ni):LiNbO3晶体全息记录性能的影响

分别采用514 nm绿光、488 nm蓝光和390 nm紫外光作为敏化光,633 nm红光作为记录光,详细研究了敏化光波长对氧化(Fe,Ni):LiNbO3晶体全息记录性能的影响.结果表明:随着敏化光波长的逐渐减小,氧化(Fe,Ni):LiNbO3晶体的非挥发全息记录性能逐渐优化,390 nm紫外光是这三种敏化光中最优的敏化光.考虑敏化光的吸收,为了在双中心全息记录中获得最优的性能,应当选择合适波长的敏化光:一方面短波长敏化光能有效地敏化深中心;另一方面短波长敏化光的吸收太强(如对光折变效应无用的基质吸收),不能沿厚度方向有效地敏化晶体,所以实际上需折衷考虑,并从理论上给予了解释.     

对地观测平台恒星敏感器离焦成像折中设计分析

从对地观测平台角秒量级姿态确定需求出发,在构建星敏感器惯性系成像模型的基础上指出,恒星在成像面上的定位误差是星敏感器姿态确定误差的主要来源。同时,结合理想光学系统离焦模型,分析了星敏感器主要性能指标间的量化关系,并给出了成像面定位误差最低限。仿真结果表明,从优化系统性能考虑,成像模糊区直径为2~3个像元的配置是利用星敏感器焦平面的“轻微离焦”来实现亚像元定位的最佳方案,定位误差可达0.2个像元,能够满足星敏感器惯性姿态确定精度4″~5″的要求。理论分析和数值仿真结果可为后续星敏感器指标的提出及仪器设计提供技术参考。     

激光熔覆硬质合金强化化纤切断刀的研究

在机械压制法预置硬质合金WC/Co粉末的条形55Si2Mn弹簧钢上,用激光熔覆方法制备了化纤切断刀.调整熔覆层粉末配方中Al、TiC的加入量,结果表明加适量的Al粉能有效地抑制气孔,加TiC粉末能提高熔覆硬度.通过优化激光熔覆工艺参数,得到了无气孔缺陷、组织性能良好、硬度达到HV0.21250的激光熔覆层,达到了化纤切断刀的性能要求.     

Simultaneous Determination of Seven Lipophilic and Hydrophilic Components in Salvia miltiorrhiza Bunge by LC-MS/MS Method and Its Application to a Transport Study in a Blood-Brain-Barrier Cell Model

Salvia miltiorrhiza Bunge (SM) has been extensively used in Alzheimer’s disease treatment, the permeability through the blood-brain barrier (BBB) determining its efficacy. However, the transport mechanism of SM components across the BBB remains to be clarified. A simple, precise, and sensitive method using LC-MS/MS was developed for simultaneous quantification of tanshinone I (TS I), dihydrotanshinone I (DTS I), tanshinone IIA (TS IIA), cryptotanshinone (CTS), protocatechuic aldehyde (PAL), protocatechuic acid (PCTA), and caffeic acid (CFA) in transport samples. The analytes were separated on a C18 column by gradient elution. Multiple reaction monitoring mode via electrospray ionization source was used to quantify the analytes in positive mode for TS I, DTS I, TS IIA, CTS, and negative mode for PAL, PCTA, and CFA. The linearity ranges were 0.1–8 ng/mL for TS I and DTS I, 0.2–8 ng/mL for TS IIA, 1–80 ng/mL for CTS, 20–800 ng/mL for PAL and CFA, and 10–4000 ng/mL for PCTA. The developed method was accurate and precise for the compounds. The relative matrix effect was less than 15%, and the analytes were stable for analysis. The established method was successfully applied for transport experiments on a BBB cell model to evaluate the apparent permeability of the seven components.     

Discovery of Novel Pleuromutilin Derivatives as Potent Antibacterial Agents for the Treatment of MRSA Infection

A series of novel pleuromutilin derivatives containing nitrogen groups on the side chain of C14 were synthesized under mild conditions. Most of the synthesized derivatives displayed potent antibacterial activities. Compound 9 was found to be the most active antibacterial derivative against MRSA (MIC = 0.06 μg/mL). Furthermore, the result of time-kill curves showed that compound 9 had a certain inhibitory effect against MRSA in vitro. Moreover, according to a surface plasmon resonance (SPR) study, compound 9 (K_D = 1.77 × 10⁻⁸ M) showed stronger affinity to the 50S ribosome than tiamulin (K_D = 2.50 × 10⁻⁸ M). The antibacterial activity of compound 9 was further evaluated in an MRSA-infected murine thigh model. Compared to the negative control group, tiamulin reduced MRSA load (~0.7 log₁₀ CFU/mL), and compound 9 performed a treatment effect (~1.3 log₁₀ CFU/mL). In addition, compound 9 was evaluated in CYP450 inhibition assay and showed only moderate in vitro CYP3A4 inhibition (IC₅₀ = 2.92 μg/mL).     

p型G aSb窗口层在热光伏电池中的应用研究

为了提高GaSb热光伏电池的转换效率,在电池结构中引入p+-GaSb窗口层,研究了生长基底、衬底温度和反应物源温度对p+-GaSb薄膜性能的影响,并优化了电池结构中p+-GaSb窗口层的厚度和掺杂浓度.实验结果表明,生长基底和温度等制备参数影响着p+-GaSb薄膜的结构特性和电学特性,而且,较薄的高掺杂p+-GaSb层有利于提高电池性能.通过测试和仿真,热光伏电池的转换效率达到9.49;(AM1.5测试)和20.34;(AFORS-HET仿真).     

塞曼效应仿真实验平台

塞曼效应实验是学生了解原子具有磁矩和空间取向量子化现象的重要实验,至今塞曼效应仍是研究能级结构的重要方法之一.为了能够让学生更加清楚地了解塞曼效应实验的基本原理和操作规程,针对教学中的重点和难点,运用flash软件制作出塞曼效应仿真实验.该程序可全程高度仿真实验过程,具有界面友好、易于操作、无需安装等优点.为实验教学提供了一种新的辅助方式.     

相对性区域创新指数与经济周期挖掘

提出了一类新的相对性区域创新指数,并采用世界专利申请数据对其进行了具体计算.基于区域创新同经济发展水平之间的超线性关系,该指数消除了经济发展水平对创新能力的影响,可以实现对不同发展水平的经济体之间进行有效的创新能力横纵对比.该创新指数尽管极其简单,却揭示出一系列迥异于传统认知的现象,例如中国大陆地区的技术创新能力在1980年代就已经位居世界前列.采用该指数,不但可以在较高水平上解释世界各国的经济增长,还发现它同经济增长率之间的相关性存在一个20年的经济周期.这些结果显示,该指数作为一个单一性指标,以极小的数据依赖就实现了较高程度的解释性,不但重新定位了世界各经济体的创新能力,对深入理解创新同经济发展之间的关系提供了新的角度,而且暗示着这类相对性经济指标的发展潜力与应用空间.     

1200 V碳化硅功率MOSFET低温特性的实验表征及分析

碳化硅功率MOSFET是宽禁带功率半导体器件的典型代表,具有优异的电气性能。基于低温环境下的应用需求,研究了1200 V碳化硅功率MOSFET在77.7 K至300 K温区的静/动态特性,定性分析了温度对碳化硅功率MOSFET性能的影响。实验结果显示,温度从300 K降低至77.7 K时,阈值电压上升177.24%,漏-源极击穿电压降低32.99%,栅极泄漏电流降低82.51%,导通电阻升高1142.28%,零栅压漏电流降低89.84%(300 K至125 K)。双脉冲测试显示,开通时间增大8.59%,关断时间降低16.86%,开关损耗增加48%。分析发现,碳化硅功率MOSFET较高的界面态密度和较差的沟道迁移率,是导致其在低温下性能劣化的主要原因。     

Controllable soliton transition and interaction in nonlocal nonlinear media

Nonlinear Dynamics - Two kinds of controllable evolutions of optical solitons are predicted in nonlocal nonlinear media by gradually tuning the characteristic length of response function. On the...