LYVE-1 在甲状腺乳头状癌的表达和意义

目的 观察淋巴管透明质酸受体1（LYVE-1）的表达和癌周组织中淋巴管的生成情况在甲状腺恶性肿瘤的变化及转 移中的作用。方法 应用免疫组织化学和real-time PCR方法检测45 例甲状腺乳头状癌中央区、癌周边区和正常甲状腺组织中的LYVE-1及其mRNA 表达情况,并计算淋巴管密度（LVD）。结果 甲状腺乳头状癌周边区LVD 高于甲状腺乳头状癌中央区,而正常组织中很少见LYVE-1 阳性的微淋巴管;甲状腺乳头状癌周边区LVD 与淋巴结转移有密切关系（P＜0.05）。结论 LYVE-1是一种特异性较高的淋巴管内皮特异性标志物,对淋巴管生成促进甲状腺乳头状癌的淋巴结转移。     

高功率多脉冲调制器研究

 研制了能产生多脉冲的高功率脉冲调制器，该调制器由初级储能系统、带绕式变压器、水介质Blumlein线和场发射二极管组成。在场发射二极管上获得3个峰值功率大于20 GW，半高脉宽约60 ns，脉冲间隔约15 ms，电压约400 kV的高功率电脉冲。理论计算、模拟计算与实验结果基本一致。分析表明主开关恢复时间是影响调制器输出脉冲时间间隔的主要因素。     

Bi1.8Pb0.4Sr2Ca2.2Cu3Oy的磁通运动与临界电流特征

制备了银包套的Bi_1.8Pb_0.4Sr₂Ca_2.2Cu₃O_y带材。微结构观察证明样品是高度织构化的Bi2223单相。输运测量发现J_c(T,B,θ,φ)和R(T,B,θ,φ)均与θ有关,与φ无关(T=77K,B<1T),式中的θ和φ分别表示磁场与ab面和电流的夹角。求得了磁通运动的激活能。提出了热激活磁通弯结的形成与运动模型,并用London理论计算了弯结 关键词：     

Influences of total ionizing dose on single event effect sensitivity in floating gate cells

The influences of total ionizing dose(TID) on the single event effect(SEE) sensitivity of 34-nm and 25-nm NAND flash memories are investigated in this paper. The increase in the cross section of heavy-ion single event upset(SEU) in memories that have ever been exposed to TID is observed, which is attributed to the combination of the threshold voltage shifts induced by γ-rays and heavy ions. Retention errors in floating gate(FG) cells after heavy ion irradiation are observed.Moreover, the cross section of retention error increases if the memory has ever been exposed to TID. This effect is more evident at a low linear energy transfer(LET) value. The underlying mechanism is identified as the combination of the defects induced by γ-rays and heavy ions, which increases the possibility to constitute a multi-trap assisted tunneling(mTAT) path across the tunnel oxide.     

Investigation of flux dependent sensitivity on single event effect in memory devices

Heavy-ion flux is an important experimental parameter in the ground based single event tests. The flux impact on a single event effect in different memory devices is analyzed by using GEANT4 and TCAD simulation methods. The transient radial track profile depends not only on the linear energy transfer(LET) of the incident ion, but also on the mass and energy of the ion. For the ions with the energies at the Bragg peaks, the radial charge distribution is wider when the ion LET is larger. The results extracted from the GEANT4 and TCAD simulations, together with detailed analysis of the device structure, are presented to demonstrate phenomena observed in the flux related experiment. The analysis shows that the flux effect conclusions drawn from the experiment are intrinsically connected and all indicate the mechanism that the flux effect stems from multiple ion-induced pulses functioning together and relies exquisitely on the specific response of the device.     

深亚微米SRAM质子单粒子翻转实验研究

宇航半导体器件运行在一个复杂的空间辐射环境中,质子是空间辐射环境中粒子的重要组成部分,因而质子在半导体器件中导致的辐射效应一直受到国内外的关注。利用兰州重离子加速器(Heavy Ion Research Facility In Lanzhou) 加速出的H2 分子打靶产生能量为10 MeV 的质子,研究了特征尺寸为0.5/0.35/0.15 μm体硅和绝缘体上硅(SOI) 工艺静态随机存储器(SRAM) 的质子单粒子翻转敏感性,这也是首次在该装置上开展的质子单粒子翻转实验研究。实验结果表明特征尺寸为亚微米的SOI 工艺SRAM器件对质子单粒子翻转不敏感,但随着器件特征尺寸的减小和工作电压的降低,SOI 工艺SRAM器件对质子单粒子翻转越来越敏感;特征尺寸为深亚微米的体硅工艺SRAM器件单粒子翻转截面随入射质子能量变化明显,存在发生翻转的质子能量阈值,CREME-MC模拟结果表明质子在深亚微米的体硅工艺SRAM器件中通过质子核反应导致单粒子翻转。Microelectronic devices are used in a harsh radiation environment for space missions. Among all the reliability issues concerned, proton induced single event upset (SEU) is becoming more and more noticeable for semiconductor components exposed on space. In this work, an experimental research of SEU induced by 10 MeV proton for static random access memory (SRAM) of 0.5, 0.35 and 0.15 m feature size is carried out on HeavyIon Research Facility in Lanzhou for the rst time. The experimental results show that proton induced SEUs in submicron and deep-submicron (SRAMs) are dominated by secondary ions generated by proton nuclear reaction events. The silicon-on-insulator SRAMs characters natural radiation-hardened SEU by proton. For the deep-submicron bulk-silicon technology SRAM, the proton SEU cross section is closely related to the proton energy and there is a threshold energy for the SEU occurrence by proton indirect ionization. CREME-MC simulation indicates that the SEU events in deep-submicron SRAM are induced by the proton nuclear reaction.     

Impact of energy straggle on proton-induced single event upset test in a 65-nm SRAM cell

This paper presents a simulation study of the impact of energy straggle on a proton-induced single event upset(SEU)test in a commercial 65-nm static random access memory cell. The simulation results indicate that the SEU cross sections for low energy protons are significantly underestimated due to the use of degraders in the SEU test. In contrast, using degraders in a high energy proton test may cause the overestimation of the SEU cross sections. The results are confirmed by the experimental data and the impact of energy straggle on the SEU cross section needs to be taken into account when conducting a proton-induced SEU test in a nanodevice using degraders.     

重离子辐照带有ECC的65 nm SRAM器件“伪多位翻转”特性研究

为了提高纠错编码（ECC）的有效性,先进的静态随机存储器（SRAM）多采用位交错结构。但是,在没有物理版图信息的情况下,位交错设计使得从辐照测试数据中提取出多单元翻转（MCU）变得更加困难。运用Bi离子辐照带有ECC的65 nm SRAM器件,研究了该款器件在重离子辐照下的敏感性。为"伪多位翻转（FMBU）"以及MCU的数据分析提供了理论指导和帮助,完善了判别MCU的基本法则。除此之外,研究结果表明,ECC的汉明编码对于纳米器件的效果不够理想。在未来的空间应用中,需考虑更高层次的编码算法来抵抗单粒子翻转。In order to improve the robustness of error-correcting codes (ECC), modern static random access memory (SRAM) always use bit-interleaving structure. However, in the absence of physical layout information, the bit-interleaving design makes it more difficult to extract the multiple-cell upset (MCU) from the test data. In this paper, the sensitivity of Bi ion irradiation was investigated in a 65 nm technology SRAM with ECC. The experimental results provide a theoretical guidance and help for the fake multiple-bit upset (FMBU) and MCU data analyzing, which improve and perfect the basic rules extracting MCU from the test data. In addition, the results show that the performance of hamming encoding is not ideal in Nano scale SRAM. In the future of space applications, it is necessary to consider more advanced algorithms to against SEU.     

电离总剂量对纳米SRAM器件单粒子翻转敏感性的影响

电离总剂量（TID）与单粒子效应（SEE）是纳米SRAM器件在航天应用中的主要威胁。随着CMOS工艺的进步,两种辐射效应在纳米SRAM器件中的协同效应出现了一些新现象,有必要进一步开展深入研究。利用γ射线以及不同种类重离子对两款纳米SRAM器件开展了辐照实验,研究了不同辐照参数、测试模式以及数据图形条件下,电离总剂量对单粒子翻转（SEU）敏感性的影响。研究结果表明,γ射线辐照过后,存储单元中反相器开关阈值减小,漏电流增大,导致SRAM存储单元抗翻转能力降低,SEU截面有明显增大;未观察到"印记效应",数据图形对测试结果没有明显影响;多位翻转（MBU）比例无明显变化。     

Neutron-induced single event upset simulation in Geant4 for three-dimensional die-stacked SRAM

Three-dimensional integrated circuits(3D ICs)have entered into the mainstream due to their high performance,high integration,and low power consumption.When used in atmospheric environments,3D ICs are irradiated inevitably by neutrons.In this paper,a 3D die-stacked SRAM device is constructed based on a real planar SRAM device.Then,the single event upsets(SEUs)caused by neutrons with different energies are studied by the Monte Carlo method.The SEU cross-sections for each die and for the whole three-layer die-stacked SRAM device is obtained for neutrons with energy ranging from 1 MeV to 1000 MeV.The results indicate that the variation trend of the SEU cross-section for every single die and for the entire die-stacked device is consistent,but the specific values are different.The SEU cross-section is shown to be dependent on the threshold of linear energy transfer(LETth)and thickness of the sensitive volume(Tsv).The secondary particle distribution and energy deposition are analyzed,and the internal mechanism that is responsible for this difference is illustrated.Besides,the ratio and patterns of multiple bit upset(MBU)caused by neutrons with different energies are also presented.This work is helpful for the aerospace IC designers to understand the SEU mechanism of 3D ICs caused by neutrons irradiation.