电击基因转移系统的研究

电击法是一种新的生物技术，其转化效率是用化学法所得不到的．ＬＮ—１０１和ＬＮ—２０１是两种基因脉冲导入系统，能提供可以控制的高压、大电流脉冲。     

忆阻型模糊细胞神经网络在时滞脉冲控制下的全局指数同步

文章研究了忆阻型模糊细胞神经网络的全局指数同步控制问题。首先,通过采用Filippo解和可测选择理论将忆阻模糊细胞神经网络转化成一类参数不确定的神经网络,并给出一个新颖的不等式以解决模糊反馈连接权重的参数不确定问题;然后,通过设计时滞脉冲控制器,并结合李雅普诺夫函数法、脉冲不等式以及给出的新的不等式,得到驱动忆阻模糊细胞神经网络与响应忆阻模糊细胞神经网络在时滞脉冲控制下指数同步的结果;最后,通过数值模拟验证了理论结果的有效性。研究结果表明:采用合适的控制器,忆阻型模糊细胞神经网络的驱动-响应系统是可以达到指数同步的。     

电极材料对NbOx Mott忆阻器稳定性的影响

为了改善NbO_xMott忆阻器电学稳定性和一致性，提升NbO_x Mott忆阻器构建人工脉冲神经元的应用潜力，研究制备了通孔型NbO_x Mott忆阻器，并对比研究了Pt、W电极材料对器件稳定性和一致性的影响。研究结果表明，相较于常见报道的Pt电极器件，采用W电极的NbO_x Mott忆阻器表现出了更为优越的稳定性和一致性。此外，利用NbO_x Mott忆阻器搭建了振荡电路，成功实现了人工脉冲神经元的功能。基于W电极NbO_xMott忆阻器的人工脉冲神经元可以稳定振荡时间超过10⁶ s,循环耐久性可达10¹²次以上，其振荡波形的幅度及频率稳定性远好于基于Pt电极的人工脉冲神经元。进一步的XPS结果显示，在基于W电极的NbO_xMott忆阻器中，W和NbO_x界面生成了一层致密的WO_x层，有效地阻挡了氧空位在NbO_x材料中的迁移。相比之下，基...     

基于忆阻脉冲耦合神经网络的图像去噪

为解决传统脉冲耦合神经网络的参数不固定问题,在图像处理中应用忆阻元件突出的记忆属性,提出了 应用两个忆阻元器件反向并联模拟脉冲神经网络中的神经元间的连接强度,构建新型忆阻脉冲神经网络,实现 神经元间连接强度动态可变化,再将该新型网络用于图像去噪问题。通过Matlab 仿真实验,验证了改进后的 新型网络在图像去噪方面的良好性能,并通过峰值信噪比和图像相似度指标证明了该方法用于图像去噪具有 较好的效果。     

水平井段脉冲携岩数值模拟研究

水平井钻井技术已成为现代油气勘探开发的重要手段,水平井段岩屑运移不畅造成钻井过程中的高摩阻和扭矩、卡钻和憋泵等情况,影响钻具的使用寿命和钻进安全,特别是使用现有的常规携岩方法无法解决,为此,提出脉冲携岩方法。在现有水力脉冲的基础上,根据分流继能机理,建立小井眼水平井岩屑运移的流场模型,采用RNG k-ε模型、幂律模式及二次开发子程序进行数值计算,确定脉冲携岩合理的脉冲周期、占空比等参数,并研究水力脉冲条件下钻井液排量、偏心度、岩屑粒径等参数对偏心环空岩屑运移的影响,得到环空岩屑运移速度和浓度的分布规律。研究表明,在同等条件下,脉冲携岩效率更高,破坏岩屑床效果更好,降低岩屑床浓度约40%。     

气体放电管直流击穿电压测量技术的研究

为了寻找一个能有效表征气体放电管(GDT)从高阻状态转变为低阻状态的判据,在分析和实验对比现有技术的基础上,提出了利用电磁感应原理设计判据提取的方法.该方法设计了一个耦合线圈,将初级线圈串入主回路采集GDT击穿瞬间产生的微电流脉冲,将该脉冲整形后作为判据信号.对GDT击穿瞬间的电路状态进行了建模分析,首次从电路角度分析了GDT击穿瞬间出现的脉冲电流的形成原因,并指出不同的脉冲电流是由电流中脉冲分量和线性分量相互作用的结果.实验结果表明:在宽电压范围(50～5 000V)测量系统中,稳态击穿电流小于5 mA,且在上升速率为100V/s直流电压作用下,从GDT击穿到系统响应最小时间为2.06μS,最大为3.34 μS,平均为2.81 μS.     

空心阴极放电自脉冲现象的实验研究

研究了氩气中圆柱形空心阴极放电的自脉冲现象.测试了空心阴极放电不同阶段的伏安特性及自脉冲频率和电流脉冲上升沿随放电平均电流、气压和电路电容的变化;讨论了自脉冲的形成机理. 结果表明,自脉冲现象出现在空心阴极放电的负阻特性阶段,并具有稳定的频率.自脉冲频率随平均电流的增加而线性增大,气压和孔径的乘积pD值对频率的影响与其大小有关,但电极间的并联电容不影响脉冲频率;电流脉冲上升沿几乎与平均电流、气压或并联电容无关. 实验结果表明,自脉冲现象是空心阴极本身的一种特征放电过程.     

忆阻混沌系统的同步

忆阻器之所以引起了人们的大量关注,是因为它具有其一些特殊的特点,在普通的混沌系统中代替蔡氏二极管通过用忆阻器,因之得到了一个忆阻混沌系统;研究了忆阻混沌系统的同步,通过用Lyapunov稳定性理论,并设计一个脉冲控制器来实现忆阻混沌系统在不同的条件下的同步,从理论分析上说明了结果的有效性。     

基于忆阻器的鉴相电路设计与分析

分析忆阻器的基本理论,推导忆阻器阻值与电量、时间的函数关系,使用Simulink建立忆阻器模型,并验证该模型在正弦信号激励下,电流和电压具有滞回特性.设计基于忆阻器的鉴相电路,将相位差测量转化成对脉冲宽度的测量,对方法进行理论分析,并通过仿真实验验证了电路的功能.通过仿真、计算,得到忆阻器在边界非线性效应的影响下,非线性误差为9.82%.     

激光解吸/激光电离-质谱法二恶英及其关联物的在线检测

本研究使用毛细管直接进样法,利用气体绝热膨胀过程的冷却效果使样品和载气分子凝结、浓缩于毛细管端口,再利用脉冲激光解吸技术将样品解吸以脉冲气流的方式引入质谱,通过考察毛细管加热温度、解吸激光能量、解吸激光与电离激光之间的延迟时间等因素确立了有效的分析条件,实现了对氯苯酚、五氯苯等5种化合物的在线检测。相对于传统的连续导入方式,脉冲式导入方式增加了样品浓缩的环节有利于降低检出限。同时本实验中高密度飞秒电离激光的采用也确保了解吸后的分子能够被共振增强双光子电离,增强了分析的灵敏度。     

Combinational electroporation and transplantation approach to studying gene functions in avian embryos

Gene transfection is an indispensable approach for studying gene function since it provides important information on gain- and/or loss-of-function. Chick embryos are also extensively employed for studying bio- logical function since they are easily accessible and can be maintained alive after manipulation. The combination of both techniques presents a powerful approach to under- standing how genes regulate embryo development. Fur- thermore, combining these approaches with tissue transplant techniques make even more attractive for elu- cidate gene function. Electroporation, employing parallelly fashioned electrodes, has been widely used in chick embryos. However, experimenters have been frustrated by unsuccessfully transfection in some embryonic tissue of interest because the electrodes were improperly positioned.We presently demonstrated the different patterns of orga- nizing and positioning the electrodes, in combination with tissue transplantation, to efficiently and specifically trans- fect the chick embryonic head, trunk neural tube, heart tube, somites and neural crest cells with the GFP reporter gene.     

原生质体融合和转化技术的进展

本文通过文献查阅,对原生质体融合和转化技术进行了下列综述: 原生质体融合—灭活融合;电融合;荧光标记融合;激光融合等。 原生质体转化—显微注射;脂质体法;电击穿法;基因直接转化等。     

Effect of cell history on response to helix-loop-helix family of myogenic regulators

In multinucleated heterokaryons formed from the fusion of differentiated muscle cells to either hepatocytes or fibroblasts, muscle-specific gene expression is activated, liver-specific gene expression is repressed, and there are changes in the location of the Golgi apparatus. An understanding of the regulatory mechanisms that underlie this plasticity is of particular interest given the stability of the differentiated state in vivo. We have now investigated whether MyoD or myogenin, regulators of muscle-specific gene expression that have a helix-loop-helix motif, can induce the phenotypic conversion observed in heterokaryons. When these regulators were stably or transiently introduced into fibroblasts or hepatocytes by microinjection, transfection or retroviral infection with complementary DNA in expression vectors, fibroblasts expressed muscle-specific genes, whereas hepatocytes did not. However, fusion of hepatocytes stably expressing MyoD to fibroblasts resulted in activation in the heterokaryon of muscle-specific genes of both cell types. These results imply that other regulators, present in fibroblasts but not in hepatocytes, are necessary for the activation of muscle-specific genes, and indicate that the differentiated state of a cell is dictated by its history and a dynamic interaction among the proteins that it contains.     

PRMT5 suppresses DR4-mediated CCL20 release via NF-κB pathway

Construct expression vectors of pCMV-DR4-HA and pCMV-PRMT5-Flag,and transfect them into HEK293 cells to identify the interaction between TRAIL-R1 and PRMT5 and the molecular mechanism underlying DR4-mediated inhibition of chemokine CCL20 release via TRAIL receptor 1(DR4).Inflammatory cytokine was detected by RT-PCR and ELISA after TRAIL-R1 and/or PRMT5 transfection,respectively.NF-κB activity was detected by Dual Luciferase Reporter Gene Assay.ERK1/2 phosphorylation was analyzed by Western blot.PRMT5 could inhibit DR4-activated NF-κB activity and ERK1/2 phosphorylation.PRMT5 could inhibit NF-κB activition,ERK1/2 phosphorylation as well as CCL20 secretion via binding with DR4 in HEK293 cell,suggesting that PRMT5 may involve in DR4 dependent immune regulation.     

Electrofusion of tobacco protoplasts in space

Electrofusion of plant cell protoplasts is a techniqueto induce fusion between protoplasts by the reversibleelectric breakdown of their plasma membranes. This method is reliable and not toxic compared with chemicalfusion. Some somatic plant cell hybrids have been suc-cessfully produced by this method[1—5]. However, it is notwidely applied in agriculture due to the low yield of vi-able hybrids[6]. The reasons resulting in the low yield ofhybrids might be as the followings: (1) different densit…     

体育运动中的基因兴奋剂

WADA将基因或细胞兴奋剂定义为“能增强运动能力的基因，遗传元素和／或细胞的非治疗性的使用”．遗传学和基因学的新的研究结果不仅将用于疾病的诊断和治疗，而且还将用于试图增强机体的运动能力．用于治疗疾病的基因疗法，如贫血（EPO基因）、肌肉营养不良（IGF—I基因）和外周血管疾病（血管内皮生长因子基因）等，都可能被用于兴奋剂．为保护运动员的健康和保证公平竞争，IOC、WADA和ISF（国际体育联合会）已将提高运动能力的药物和方法定义为基因兴奋剂，并禁止其使用．     

Up-regulation of endothelial nitric oxide synthase by cytochrome P450 arachidonic acid epoxygenase BM3F87V

Cytochrome P450 (CYP)-dependent metabolites of arachidonic acid, epoxyeicosatrienoic acids (EETs), have been suggested to be an endothelium-derived hyperpolarizing factor (EDHF). However, the interaction or relation between EDHF and endothelial nitric oxide synthase (eNOS) is still to be elucidated. In the present study, the regulation of eNOS by endogenous EDHF is examined. The cytochrome P450 epoxygenase BM3F87V is cloned into the mammalian expression vector pCB6. Cultured bovine aortic endothelial cells (BAECs) less than 4 passages are used and transfected with BM3F87V. The effects of endogenous EETs result from BM3F87V transfection on eNOS are assessed in the endothelial cells by Western blot and Northern blot, and eNOS activity is also measured by the conversion of L-arginine to L-citrulline. Compared to transfection with the empty pCB6 vector, transfection of BAECs with BM3F87V significantly elevates the levels of eNOS protein expression, which is markedly inhibited by treatment with CYP inhibitor 17-ODYA. BM3F87V transfection also elevates the eNOS mRNA level and increases the eNOS activity. This study suggests that EDHF up-regulates eNOS gene expression.     

Enhancement of the efficiency of PEI/liposome transfection by magnetofectins formed via electrostatic self-assembly

One of the major challenges for successful gene therapy is improving the transfection efficiency of non-viral vectors. Magnetic nanoparticles (MNPs) have been developed as enhancers of non-viral vehicles. We prepared MNPs and modified them with polyethyleneimine (PEI), citric acid (CA) or carboxylmethyl-dextran (CMD). Both positively charged MNPs (MNPs@PEI) and negatively charged MNPs (MNPs@CA, MNPs@CMD) could spontaneously form transfection complexes (magnetofectins) with plasmid DNA and PEI/liposome via electrostatic self-assembly. Our results showed as-prepared magnetofectins apparently enhanced PEI/liposome transfection efficiency and/or gene expression level into COS-7 cells with reduced transfection time from 4 h to 15 min under a magnetic field in vitro. Meanwhile, the effect of magnetofection was cell line-dependant. These results suggest that charged MNPs could improve transfection efficiency for non-viral vectors by simply mixing with them and by exerting a magnetic force. Thus such MNPs provide a convenient platform for further applications of gene delivery.     

心电图机报警器研制

通过深入分析心电图机的具体工作原理和常见故障以及心电图机的技术指标、特性、用途、标准、使用注意事项等，设计出保障心电图机安全工作的报警器．报警器的系统由心率报警器、电极脱落报警器、心跳中断报警器、超压、欠压报警器、漏电报警器、电池电压（直流电压）低落报警器、保险丝熔断报警器、走纸电机转速过高、过低报警器、简易心电图机校验器、微型心脏除颤急救器等组成．使用该报警系统，可确保心电图机安全工作，保证操作者和病人的安全．