电子束辐射对LED发光性能的影响

研究了低能电子束辐照对发光二极管(Light emitting diode,LED)发光性能的影响。利用实验室加速器提供的电子束模拟空间电子辐射,分别对发不同颜色的光的LED进行不同剂量的辐照,并对比辐照前后的LED的电学性质及光学性质的变化。在电子束辐照下,LED的发光强度提高,同时在统计了大量LED后,发现这些LED的发光强度的离散性变好。对经电子束辐照后的LED进行电流加速老化实验,发现电子束辐照后的LED的发光强度下降趋势相比未经辐照的LED更为明显。同时利用电子束辐照机理对实验结果进行分析和讨论。     

一种高增益宽频带的增益自举运算放大器

设计了一个应用于高精度流水线结构ADC中的高增益、宽频带全差分运算跨导放大器(OTA).整体运放采用了2级结构,第一级采用套筒共源共栅结构,并结合增益自举技术来提高增益;第二级采用共源放大器结构作为输出级,以增大运放的输出信号摆幅.该设计采用UMC 0.18μm CMOS工艺,版图面积为320μm×260μm.仿真结果显示:在1.8 V电源供电5 pF负载下,在各个工艺角及温度变化下增益高于120 dB,增益带宽积(GBW)大于800 MHz,而整个运放消耗16.36 mA的电流,FOM值为306 MHz·pF/mA.     

Fiber-shaped organic electrochemical transistors for biochemical detections with high sensitivity and stability

Precise and continuous monitoring of biochemicals by biosensors assists to understand physiological functions for various diagnostics and therapeutic applications. For implanted biosensors, small size and flexibility are essential for minimizing tissue damage and achieving accurate detection. However, the active surface area of sensor decreases as the sensor becomes smaller,which will increase the impedance and decrease the signal to noise ratio, resulting in a poor detection limit. Taking advantages of local amplification effect, organic electrochemical transistors(OECTs) constitute promising candidates for high-sensitive monitoring. However, their detections in deep tissues are rarely reported. Herein, we report a family of implantable, fiber-shaped all-in-one OECTs based on carbon nanotube fibers for versatile biochemical detection including H_2O_2, glucose, dopamine and glutamate. These fiber-shaped OECTs demonstrated high sensitivity, dynamical stability in physiological environment and antiinterference capability. After implantation in mouse brain, 7-day dopamine monitoring in vivo was realized for the first time.These fiber-shaped OECTs could be great additions to the "life science" tool box and represent promising avenue for biomedical monitoring.     

Second-order Nonlinearity Induced Unconventional Photon Blockade

In the recent publications (Gerace and Savona, Phys. Rev. A 89(R), 031803 2014; Zhou et al., Opt. Express 24, 17332 2016), the unconventional photon blockades are studied in a three-mode-second-order-nonlinearity system with linear coupling between the two low frequency modes. In this paper, the unconventional photon blockade is studied in a complementary case with linear coupling between the two high frequency modes. By solving the master equation in the steady-state limit and calculating the zerodelay- time second-order correlation function, a strong photon antibunching is found in this three-mode-second-order-nonlinearity system. The optimal antibunching conditions are derived and the numerical simulations confirm the optimal conditions. Our scheme can be used as a tunable single-photon source.

     

浅谈2018年诺贝尔化学奖:驾驭进化的力量

In living organisms, protein functions are constantly evolving over generations throughout the history. Through iterative rounds of genetic mutations and natural selection of fit phenotypes, protein functions have been gradually optimized. This process could be mimicked and even greatly accelerated in the laboratory, when the selection pressure is directly applied to biomolecules of interest, which forms the basis of a technique called directed evolution. The Nobel Prize in chemistry 2018 was awarded jointly to Frances Arnold, George Smith and Gregory P. Winter for their pioneering contributions to the development and applications of directed evolution. Here we briefly review the history of this technique and its impact on renewable energy and pharmaceutical industry.     

基于不同社会责任承担模式的闭环供应链决策研究

供应链成员企业对不同社会责任承担模式有自己的偏好选择,探讨供应链成员企业承担的社会责任对供应链决策的影响.对于可能的任何一种社会责任承担模式,企业承担社会责任均会使产品销售价格降低、需求量增加、回收量增加.承担企业社会责任虽然会使自身收益减少,但其他成员和系统的收益却会增加,有利于增加消费者剩余,实现社会福利最大化.当承担的社会责任程度较大时,供应链成员企业能保持长期合作关系,使供应链正常运行.当承担的社会责任程度都较小时,由于供应链成员企业之间对社会责任承担模式的偏好存在矛盾将难以维持供应链合作,最终会导致供应链断链.     

A Theoretical and Empirical Comparison of Gradient Approximations in Derivative-Free Optimization

Foundations of Computational Mathematics - In this paper, we analyze several methods for approximating gradients of noisy functions using only function values. These methods include finite...     

Diphenyl ethers from a marine-derived isolate of Aspergillus sp. CUGB-F046

One new diphenyl ether, diorcinol K (1), along with three known compounds, diorcinols D (2), F (3) and I (4) were isolated from the fermentation media of a marine-derived fungus Aspergillus sp. CUGB-F046 which was isolated from a sediment sample collected from the Bohai Sea, China. Their structures were elucidated by detailed spectroscopic methods. Compounds 1, 2 and 4 displayed significant antibacterial activities against Staphylococcus aureus and methicillin-resistant S. aureus with MIC values of 3.125, 6.25 and 6.25 μg/mL, respectively.     

集成电路氧化层失效定位技术研究

介绍了一种针对集成电路氧化层失效的定位和分析技术。采用光发射显微镜、光致电阻变化技术,对比出电路中不同的发光机构或电阻变化点。结合电路故障假设法和版图分析,对氧化层失效位置进行定位。最终,采用制样和物理分析方法,找到失效原因。案例分析表明,该方法精确、快速,可应用于CMOS集成电路的栅氧化层、双极集成电路的MOS电容氧化层、GaAs集成电路的MIM电容的失效定位,减少了后续FIB或RIE等物理分析方法的工作量,提高了失效分析的成功率。     

基于模块化多电平拓扑的谐振变换器设计

在海洋科学研究和海洋观测领域中,水下系统的供电方式大多是岸基负高压传输到海底接驳设备。海底接驳设备中的功率变换器将岸基电源的数千伏至十几千伏的直流高压转换成低压375 V供海底设备供电。针对变换器高电压输入、宽电压范围输入及输入输出电压变比大的技术难点,提出了模块化多电平的LLC谐振变换器拓扑结构,文中对变换器进行了模型搭建和电路仿真,并完成了一台40 kW工程样机的设计,最后根据仿真和实验结果验证了模块化多电平谐振变换器工作原理的正确性及可行性。