基于分子参数的药物小肠吸收预测模型

选择100个化合物作为数据集,随机选取其中80个为训练集,其他分子为验证集,并为每个化合物分子计算了30个参数.通过采用五种不同多元线性回归分析方法对其训练模拟,建立了数学模型,并用验证集检验了所建模型的预测能力.结果发现向后筛选法为最优小肠吸收建模方法.由该法所建模型的统计结果良好(R2>0.80),应用于验证集时也表现出较强预测能力.该模型确定了对小肠吸收影响较大的分子参数,有助于指导进一步的新药筛选和开发.     

偏振选择可调谐双带太赫兹吸收器

提出并研究了一种偏振选择可调谐双带太赫兹吸收器。吸收器由顶层方形劈裂石墨烯环、中间SiO₂介质层以及底层金反射层组成。基于时域有限差分法的仿真结果显示,该吸收器在不同偏振光入射下均可以实现双带高效率吸收。x偏振光时在7.86和12.63THz处的吸收率分别为97.9%和91.2%;y偏振光时在6.30和10.52THz处的吸收率分别为94.1%和93.2%。通过改变石墨烯费米能级,可以对两个偏振的双带吸收峰波长进行调谐。此外,研究了介质层厚度和石墨烯劈裂环的物理参数对共振吸收峰的影响。因为在两个偏振状态下都能产生双带高吸收,所以此吸收器在太赫兹偏振成像、太赫兹传感、选择性光谱检测和偏振复用等领域有重要的潜在应用价值。     

Effects of Low-Damage Plasma Treatment on the Channel 2DEG and Device Characteristics of AlGaN/GaN HEMTs

We investigate the effects of remote nitride-based plasma treatment on the channel carrier and device characteristics of AlGaN/GaN high electron mobility transistors(HEMTs).A 200 W NH₃/N₂ remote plasma causes little degeneration of carrier mobility and an increase in electron density due to surface alteration,which results in a decrease in sheet resistance and an increase in output current by 20-30%.Improved current slump,suppressed gate leakage current,and improved Schottk...     

High-frequency enhancement-mode millimeterwave AlGaN/GaN HEMT with an fT/fmax over 100 GHz/200 GHz

Ultra-thin barrier (UTB) 4-nm-AlGaN/GaN normally-off high electron mobility transistors (HEMTs) having a high current gain cut-off frequency (f_T) are demonstrated by the stress-engineered compressive SiN trench technology. The compressive in-situ SiN guarantees the UTB-AlGaN/GaN heterostructure can operate a high electron density of 1.27×10¹³cm^-2, a high uniform sheet resistance of 312.8 Ω /□, but a negative threshold for the short-gate devices fabricated on it. With the lateral stress-engineering by full removing in-situ SiN in the 600-nm SiN trench, the short-gated (70 nm) devices obtain a threshold of 0.2 V, achieving the devices operating at enhancement-mode (E-mode). Meanwhile, the novel device also can operate a large current of 610 mA/mm and a high transconductance of 394 mS/mm for the E-mode devices. Most of all, a high f_T/f_max of 128 GHz/255 GHz is obtained, which is the highest value among the reported E-mode AlGaN/GaN HEMTs. Besides, being together with the 211 GHz/346 GHz of f_T/f_max for the D-mode HEMTs fabricated on the same materials, this design of E/D-mode with the realization of f_max over 200 GHz in this work is the first one that can be used in Q-band mixed-signal application with further optimization. And the minimized processing difference between the E- and D-mode designs the addition of the SiN trench, will promise an enormous competitive advantage in the fabricating costs.     

产生毫微秒脉冲高压的螺旋形带状线发生器的研究

本文叙述了能产生毫微秒脉冲高压的螺旋形带状线发生器(以下简称SSLG)的基本原理,给出了具有一个短路开关,内端为高压输出端,外端接地的SSLG的设计方法,并提供了为便携式X光发生器设计的SSLG的制作工艺。对该发生器电性能的实验研究表明:该发生器能输出脉宽40100ns、电压100kV的高压脉冲,接上X光管负载时,在距X光管输出窗1m处能得到4070R的X光辐照量。     

数据中心综合布线系统设计浅析

结合数据中心的特点,从综合布线系统的空间构成、拓扑结构、系统配置设计、产品选择及通道设计等方面进行了论述.     

In-situ SiN combined with etch-stop barrier structure for high-frequency AlGaN/GaN HEMT

The etch-stop structure including the in-situ SiN and AlGaN/GaN barrier is proposed for high frequency applications.The etch-stop process is realized by placing an in-situ SiN layer on the top of the thin AlGaN barrier.F-based etching can be self-terminated after removing SiN,leaving the AlGaN barrier in the gate region.With this in-situ SiN and thin barrier etch-stop structure,the short channel effect can be suppressed,meanwhile achieving highly precisely controlled and low damage etching process.The device shows a maximum drain current of 1022 mA/mm,a peak transconductance of 459 mS/mm,and a maximum oscillation frequency(fmax)of 248 GHz.     

N和F共掺杂C3N4的制备及其可见光催化性能

针对氮化碳（C₃N₄）光生电荷易复合、光催化性能有限的不足,我们制备N和F共掺杂C₃N₄（NF-C₃N₄）,以提升其光催化性能。利用NH₄F在高温下原位分解产生的HF和NH₃,对C₃N₄刻蚀的同时实现N和F双元素共掺杂。以氯化铵（NH₄Cl）为对照,制备N掺杂C₃N₄（N-C₃N₄）。利用扫描电子显微镜（SEM）、能谱仪（EDS）、X射线光电子能谱（XPS）、X射线衍射（XRD）、比表面积测试和电化学表征手段研究N、F共掺杂对C₃N₄形貌、成分、结构和物化性质等的影响规律。相比于C₃N₄和N-C₃N₄,NF-C₃N₄呈多孔状,比表面积增大,光生电荷的生成、分离和转移均被促进,NF-C₃N₄光催化还原Cr （Ⅵ）的速率是C₃N₄的2.6倍、N-C₃N₄的1.7倍。进一步考察了不同前驱体（尿素、双氰胺和三聚氰胺）对制备C₃N₄的影响,发现以尿素为前驱体的C₃N₄与NH₄F的质量比为3∶2时,NF-C₃N₄呈现最佳的光催化性能。催化剂用量、光照强度、空穴捕获剂浓度的增加和pH的降低均能提高Cr （Ⅵ）还原速率。在NF-C₃N₄浓度为0.1 g·L^-1、pH=3、c_EDTA-2Na=2 mmol·L^-1、40 min可见光照射后,Cr （Ⅵ）去除率达到90%。5次循环实验表明,优化制备的NF-C₃N₄光催化还原Cr （Ⅵ）的性能保持良好,具有较高的稳定性。     

催化材料对病毒的吸附和灭活作用及对哺乳动物细胞的毒性

 提出了以吸附和催化原理灭活病毒的设想，旨在开发出对病毒有过滤、吸附及灭活作用的高效非特异性催化材料，应用于各种防护设施，有效控制非典型肺炎（SARS）的传播．采用与SARS病毒相似的副流感病毒作为模拟对象，进行了吸附及灭活该病毒的催化材料研究，并考察了催化材料对哺乳动物细胞的毒性．结果表明，病毒气溶胶的阻留及吸附结果与基于DNA吸附的色谱分析结果相一致；部分材料可以强烈地吸附病毒（100％），甚至在强烈振荡下并洗脱至第3次，病毒也不能脱附；一些材料不仅可以吸附病毒，而且强烈振荡后的洗脱液虽然表现出一定的血凝效价，但接种鸡胚后，病毒并不增殖，说明材料具有明显的催化病毒灭活性能；对细胞毒性极低的材料可以用在与人体接触的防护材料和设施中．筛选出的性能优异的催化材料，拟进一步考察其对SARS病毒的灭活作用．     

Electric-stress reliability and current collapse of different thickness SiNx passivated AlGaN/GaN high electron mobility transistors

This paper investigates the impact of electrical degradation and current collapse on different thickness SiNx passivated AlGaN/GaN high electron mobility transistors.It finds that higher thickness SiNx passivation can significantly improve the high-electric-field reliability of a device.The degradation mechanism of the SiNx passivation layer under ON-state stress has also been discussed in detail.Under the ON-state stress,the strong electric-field led to degradation of SiNx passivation located in the gate-drain region.As the thickness of SiNx passivation increases,the density of the surface state will be increased to some extent.Meanwhile,it is found that the high NH 3 flow in the plasma enhanced chemical vapour deposition process could reduce the surface state and suppress the current collapse.