黄芪、黄连复方有效成分对二亚硝基哌嗪诱导气虚状态大鼠鼻咽上皮组织癌前病变的影响

目的观察二亚硝基哌嗪在正常状态和气虚状态大鼠鼻咽上皮细胞的诱癌效率差异以及黄芪、黄连复方有效成分的防护作用。方法SD大鼠每日力竭游泳10min,连续30d以建立气虚状态模型,然后分组,每组动物10只。DNP皮下注射法诱癌,并应用黄芪、黄连复方有效成分进行干预。干预完成后200天,分别取各组动物鼻咽黏膜行常规病理组织学和超微病理观察。结果力竭游泳联合DNP诱癌组动物中,鼻咽黏膜上皮细胞出现癌前病变例数(n1=8)显著多于单纯DNP诱癌组(n2=3,P<0.05),而应用益气解毒中药干预后,该类动物鼻咽黏膜上皮细胞癌前病变例数显著降低(n3=3,P<0.05)。结论气虚状态下,实验动物鼻咽黏膜上皮细胞对DNP诱癌效应更加敏感,而黄芪、黄连复方活性成分能够有效阻逆该类病理过程。

Multi-field dynamic modeling and numerical simulation of aluminum alloy resistance spot welding

In order to explore the influence of welding parameters and to investigate the Al alloy (AA) nugget formation process, a comprehensive model involving electrical-thermal-mechanical and metallurgical analysis was established to numerically display the resistance spot welding (RSW) process within multiple fields and understand the AA-RSW physics. A multi-disciplinary finite element method (FEM) framework and a empirical sub-model were built to analyze the affecting factors on weld nugget and the underlying nature of welding physics with dynamic simulation procedure. Specifically, a counter-intuitive phenomenon of the resistance time-variation caused by the transient inverse virtual variation (TIVV) effect was highlighted and analyzed on the basis of welding current and temperature distribution simulation. The empirical model describing the TIVV phenomenon was used for modifying the dynamic resistance simulation during the AA spot welding process. The numerical and experimental results show that the proposed multi-field FEM model agrees with the measured AA welding feature, and the modified dynamic resistance model captures the physics of nugget growth and the electrical-thermal behavior under varying welding current and fluctuating heat input.

带有p型柱体的三维阳极短路LIGBT结构

为了有效消除器件的逆阻现象,提出了一种带有p型柱体的三维阳极短路横向绝缘栅双极型晶体管(SA-LIGBT)结构。p型柱体位于n型缓冲层中,提高了集电极区域的短路电阻,从而使逆阻现象完全消失。另一方面,p型柱体会向漂移区注入更多的空穴,可以增强通态条件下器件的电导调制效应,降低器件的通态压降。利用三维仿真软件Crosslight-APSYS仿真研究了p型柱体的高度、宽度和长度对逆阻现象以及对器件通态压降和关断速度的影响。结果表明,当p型柱体的高度为1μm,宽度为12μm,长度为20μm时,器件的逆阻现象完全消失。通态压降为1.61 V,关断时间为110.3 ns,而传统结构LIGBT的通态压降为1.56 V,关断时间为2.33μs。