Design,fabrication and characterization of miniature RF MEMS switched capacitor based phase shifter

This paper aims to present in detail the design, fabrication and the various characterization techniques adopted in realizing a novel miniature-size switched capacitor based phase shifter. The work strives to provide an all-round development of a DMTL (Distributed MEMS Transmission Line) based phase shifting unit yielding an overall phase shift of 15° at a frequency of 15 GHz. The RF MEMS (Radio Frequency Micro Electro Mechanical Systems) Switched Capacitor based phase shifter has highly miniaturized dimensions, and is capable of solving many limitations to which the conventional Switched Capacitors are mostly susceptible. This miniature RF MEMS switched capacitor actuates at a low actuation voltage of 12 V, exhibits a fundamental frequency of vibration as high as 1.468 MHz and a switching time of 1.4 
81;s which is an improvement over the other reported designs. Various characterization results seem to validate the simulations.     

异嗪皮啶对人乳腺癌干细胞凋亡相关基因Bcl-2与Caspase家族表达的影响

目的: 研究草珊瑚中异嗪皮啶成分对乳腺癌干细胞中凋亡相关基因通路Bcl-2、Caspase-3、Caspase-8基因表达影响，进而明确其抑制增殖、迁移和促凋亡的机制。方法: 无血清培养法诱导MDA-MB-231细胞株富集乳腺癌干细胞，流式细胞仪分选CD44⁺ /CD24 ^-/low干细胞群。各组分别给予0、17、50、150、450 μmol/L异嗪皮啶，CCK-8法观察给药后24、48、72 h的细胞活力；细胞划痕实验法检测给药后细胞痕道宽度变化值并判断其对细胞迁移能力的影响；Annexin V-FITC/PI染色法检测给药后细胞总凋亡率变化；实时荧光定量PCR测定各组Bcl-2、Caspase-3、Caspase-8基因的mRNA水平；Western blot检测上述基因的蛋白水平。结果: 与对照组比较，50、150和450 μmol/L异嗪皮啶组24、48、72 h的细胞活力降低，细胞迁移能力下降。与对照组比较，50、150和450 μmol/L异嗪皮啶组细胞总凋亡率高于对照组，Bcl-2基因mRNA和蛋白表达水平降低，Caspase-3和Caspase-8基因mRNA和蛋白表达水平升高。以上结果均呈明显剂量效应关系。结论: 异嗪皮啶能通过下调Bcl-2基因表达与激活Caspase基因家族诱导乳腺癌干细胞的凋亡，同时能抑制其增殖与迁移。     

Growth Hormone Releasing Peptide-2 Attenuation of Protein Kinase C-Induced Inflammation in Human Ovarian Granulosa Cells

Cyclooxygenase-2 (COX-2) and interleukin-8 (IL-8) are two important inflammatory mediators in ovulation. Ghrelin may modulate inflammatory signaling via growth hormone secretagogue receptors. We investigated the role of ghrelin in KGN human ovarian granulosa cells using protein kinase C (PKC) activator phorbol 12, 13-didecanoate (PDD) and synthetic ghrelin analog growth hormone releasing peptide-2 (GHRP-2). GHRP-2 attenuated PDD-induced expression of protein and mRNA, the promoter activity of COX-2 and IL-8 genes, and the secretion of prostaglandin E2 (PGE₂) and IL-8. GHRP-2 promoted the degradation of PDD-induced COX-2 and IL-8 proteins with the involvement of proteasomal and lysosomal pathways. PDD-mediated COX-2 production acts via the p38, c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways; PDD-mediated IL-8 production acts via the p38, JNK and ERK pathways. GHRP-2 reduced the PDD-induced phosphorylation of p38 and JNK and activator protein 1 (AP-1) reporter activation and PDD-induced NF-κB nuclear translocation and reporter activation. The inhibitors of mitogen-activated protein kinase phosphatase-1 (MKP-1) and protein phosphatase 2 (PP2A) reduced the inhibitory effect of GHRP-2 on PDD-induced COX-2 and IL-8 expression. Our findings demonstrate an anti-inflammatory role for ghrelin (GHRP-2) in PKC-mediated inflammation of granulosa cells, at least in part, due to its inhibitory effect on PKC-induced activation of p38, JNK and NF-κB, possibly by targeting to MKP-1 and PP2A.     

两步法制备新型钛镍合金TiNi45V8In0.2的组织与性能研究

采用两步法成功制备了新型钛镍合金Ti Ni45V8In0.2,并进行XRD、SEM以及力学性能、抗应力松弛性能和耐腐蚀性能的测试与分析。结果表明:该新型合金由网状Ti Ni母相和弥散分布的V3Ni相组成,具有较佳的力学性能、抗应力松弛性能和耐腐蚀性能。与常规Ti Ni合金相比,新型合金的-40、25℃和150℃抗拉强度分别增加47.1%、39.4%、123.9%;-40、25℃和150℃屈服强度分别增加110.3%、92.5%、263.8%;腐蚀电位正移267 m V;50 h后的应力松弛从16%减小至0.5%。     

等温退火对Alnico8合金微观结构的影响

利用透射电镜(TEM)和X射线小角衍射技术(SAXS)研究了磁场等温退火工艺参数对Alnico8合金的微观组织的影响,样本的晶格结构清晰可见。结果表明,在等温退火阶段Alnico8合金通过调幅分解形成两相结构,棒状的铁磁相(1α相)粒子高度有序地弥散在弱磁性相(2α相)当中。其中,1α相的平均长度由SAXS测得,并与TEM照片数据进行了验证比对。本文着重研究了1α相粒子平均长度随等温退火处理的温度及时间参数的改变规律,结果显示样本的磁性能与其微观结构有一定相关性。     

AGA8—92DC计算方法天然气压缩因子计算

按照GB／T 17747．2—1999《天然气压缩因子的计算第2部分：用摩尔组成进行计算》,采用AGA8—92DC计算方法,用VB编程计算了天然气压缩因子。用二分法求解状态方程,精度满足工程需要。     

8mm三次谐波潘尼管的理论设计与粒子模拟研究

潘尼管是利用电子在高频结构中的位置选择机制实现注波净能量交换的回旋器件,具有高效率与低磁场的显著特点。本文在简述其基本原理的基础上,研究了其设计理论与方法,进行了相应的数值计算,设计了一只8 mm波段三次回旋谐波潘尼管:采用4开槽渐变到圆波导的开放式谐振腔高频结构,2π工作模式,束电压43.5 kV,束电流1.45 A,最后采用3D-PIC模拟软件进行验证、优化。模拟结果显示,该器件可获得37.8 kW平均输出功率,器件效率可达到60%,展示了其作为高效永磁包装器件的良好应用前景。     

基于硅与非硅复合方法的异平面空心微针制作

为了解决制备空心微针工艺复杂且成本高的问题,本文提出了采用湿法刻蚀、光刻和电镀结合的方法制备低成本空心金属微针.首先采用湿法刻蚀硅,得到280μm深的倒四棱锥锥坑;然后在锥坑上甩200μm厚的负胶SU-8填充锥坑,并通过曝光显影负胶形成微针的形貌;最后在曝光显影后的负胶上电镀50μm厚的镍得到所需形状的空心金属微针.用此方法制备的空心微针高度为350μm、壁厚为50μm,其针尖形状为三棱锥和四棱锥.通过有限元仿真分析微针强度与微针结构尺寸的关系.用此方法加工出的微针具有锥形尖,改善了刺入皮肤的效果.