交叉响应传感器鉴别β受体激动剂及其混合体系

开发了一种鉴别β受体激动剂的新型阵列传感器。该传感器由8种传感物质构成,使用96孔板酶标仪采集响应数据,结合主成分分析(PCA)、分层聚类分析(HCA)、判别分析(LDA)等模式识别方法进行数据处理,对5类β受体激动剂及其混合物进行检测。PCA结果表明,该传感器主要是基于空间结构以及氢键作用实现对β受体激动剂的识别;HCA结果显示,93个分析样本归类正确;LDA结果显示,该传感器对于β受体激动剂识别的准确率达98.9%。本方法在β受体激动剂的检测中有潜在应用价值。     

多媒体教学课件《原子核与原子核反应》的研制

本文简要介绍了多媒体教学课件《原子核与原子核反应》的内容 ,开发环境和影像数字化技术及其在多媒体课件中的应用等     

多媒体化学教科书系统《化学元素周期系》

戴安邦老师离开我们已经一年了 ,给我们留下了无限的哀思。戴老师在生前最重视基础课教学 ,他领衔四教授专著的教科书《无机化学教程》 ,为我国化学教育和无机化学的发展奠定了先期基础。他老人家长期担任基础课教学 ,重视课堂直观教学效果 ,重视有效教学辅助手段上课堂 ,教学效果优异 ,永远垂范后人 ,我们无限怀念他老人家。际此新的一轮教学改革高潮的来临 ,我们把戴老师留传给我们的丰富辅助教学手段集中表达在多媒体投影屏幕上 ,藉此增强教学效果 ,作为我们纪念戴老师丰功伟业的实际行动 ,把他遗留下来的教学经验永远延续推广。我们南开大学无机化学学科的部分师生 ,从 1 996年开始学习多媒体计算机技术 ,并萌发了创新思想 ,用三年时间 ,完成了一套多媒体化学教科书软件《化学元素周期系》 ,两张光盘 ,已由高等教育出版社出版。并获得教育部第二届全国高校优秀教学软件一等奖。教育部高教司在 1 999年 8月组织专家进行鉴定验收 ,鉴定结论是 :“《化学元素周期系》教科书软件的成果 ,是我国化学教学手段和教学方法的一项重大改革成就 ,属国内领先 ,达到了国际先进水平”。现将该项教学研究成果汇总成文 ,借以纪念我们尊敬的戴安邦老师     

New 4H silicon carbide metal semiconductor field-effect transistor with a buffer layer between the gate and the channel layer

A new 4H silicon carbide metal semiconductor field-effect transistor (4H-SiC MESFET) structure with a buffer layer between the gate and the channel layer is proposed in this paper for high power microwave applications.The physics-based analytical models for calculating the performance of the proposed device are obtained by solving one-and two-dimensional Poisson’s equations.In the models,we take into account not only two regions under the gate but also a third high field region between the gate and the drain which is usually omitted.The direct-current and the alternatingcurrent performances for the proposed 4H-SiC MESFET with a buffer layer of 0.2 μm are calculated.The calculated results are in good agreement with the experimental data.The current is larger than that of the conventional structure.The cutoff frequency (fT) and the maximum oscillation frequency (f max) are 20.4 GHz and 101.6 GHz,respectively,which are higher than 7.8 GHz and 45.3 GHz of the conventional structure.Therefore,the proposed 4H-SiC MESFET structure has better power and microwave performances than the conventional structure.     

化学教科书多媒体软件——《化学元素周期系》

介绍了《化学元素周期系》教科书软件的内容和特点,及在教学中初步试用的效果。     

Modeling of the drain-induced barrier lowering effect and optimization for a dual-channel 4H silicon carbide metal semiconductor field effect transistor

A new analytical model to describe the drain-induced barrier lowering (DIBL) effect has been obtained by solving the two-dimensional (2D) Poisson's equation for the dual-channel 4H-SiC MESFET (DCFET). Using this analytical model, we calculate the threshold voltage shift and the sub-threshold slope factor of the DCFET, which characterize the DIBL effect. The results show that they are significantly dependent on the drain bias, gate length as well as the thickness and doping concentration of the two channel layers. Based on this analytical model, the structure parameters of the DCFET have been optimized in order to suppress the DIBL effect and improve the performance.     

栅漏间表面外延层对4H-SiC功率MESFET击穿 特性的改善机理与结构优化

本文提出了一种带栅漏间表面p型外延层的新型MESFET结构并整合了能精确描述4H-SiC MESFET工作机理的数值模型,模型综合考虑了高场载流子饱和、雪崩碰撞离化以及电场调制等效应. 利用所建模型分析了表面外延层对器件沟道表面电场分布的改善作用,并采用突变结近似法对p型外延层参数与器件输出电流(I_ds)和击穿电压(V_B)的关系进行了研究.结果表明,通过在常规MESFET漏端处引入新的电场峰来降低栅极边缘的强电场峰并在栅漏之间的沟道表面引入p-n结内建电场进一步降低电场峰值,改善了表面电场沿电流方向的分布.通过与常规结构以及场板结构SiC MESFET的特性对比表明,本文提出的结构可以明显改善SiC MESFET的功率特性.此外,针对文中给定的器件结构,获得了优化的设计方案,选择p型外延层厚度为0.12 μupm,掺杂浓度为5× 10¹⁵ cm^-3,可使器件的V_B提高33%而保持I_ds基本不变.     

低交换容量阳离子交换树脂的制备及离子色谱分离性能的考察

本文制备了用于离子色谱的大孔型和微孔型两类低交换容量阳离子交换树脂。考察了表面磺化反应条件(温度、时间)与交换容量之间的变化关系及具有各种交换容量的以上两种树脂在抑制型离子色谱上对Li~+、Na~+、NH_4~+、K~+四种一价阳离子的分离效果。实验结果表明:大孔型树脂对四种离子的分离效果优于微孔型,Li~+—Na~+两者的分离度为1.35。之外,文中还计算了具有不同交换容量的表面磺化树脂的磺化层厚度。     

3D打印光敏树脂的研究进展

以光敏树脂为原料的立体快速成形3D打印技术,具有成本低、精度高、成型快等优点,在各个领域得到广泛的应用。但是,与之相适应的光敏树脂价格较高,并被国外的一些大公司所垄断,而国内相关研发起步较晚,能够生产和研发性能优良的3D打印光敏树脂的企业较少。简要阐述了3D打印光敏树脂的成形方式、固化原理和组成,重点讨论了配方设计的基本方法和评价指标,并对该领域进行了展望。     

Microwave damage susceptibility trend of bipolar transistor as a function of frequency

We conduct a theoretical study of the damage susceptibility trend of a typical bipolar transistor induced by high-power microwave (HPM) as a function of frequency. The dependences of the burnout time and the damage power on the signal frequency are obtained. Studies of the internal damage process and the mechanism of the device are carried out from the variation analysis of the distribution of the electric field, current density, and temperature. The investigation shows that the burnout time linearly depends on the signal frequency. The current density and the electric field at the damage position decrease with increasing frequency. Meanwhile, the temperature elevation occurs in the area between the p-n junction and the n-n⁺ interface due to the increase of the electric field. Adopting the data analysis software, the relationship between the damage power and the frequency is obtained. Moreover, the thickness of the substrate has a significant effect on the burnout time.