背景与目的以人骨髓间充质干细胞(human bone marrow mesenchymal stem cells,hBMSCs)作为抑癌基因IL-24的细胞载体的研究目前未见报道。应用Gateway法构建共表达增强型绿色荧光蛋白(enhanced green uorescentprotein,EGFP)基因和IL-24...背景与目的以人骨髓间充质干细胞(human bone marrow mesenchymal stem cells,hBMSCs)作为抑癌基因IL-24的细胞载体的研究目前未见报道。应用Gateway法构建共表达增强型绿色荧光蛋白(enhanced green uorescentprotein,EGFP)基因和IL-24基因的慢病毒载体,探讨其对hBMSCs的转导情况,为今后肿瘤的基因治疗奠定基础。方法应用DNA重组技术构建含有IL-24和EGFP基因的慢病毒表达载体,并与慢病毒包装系统(ViraPowerTMLentiviralPackaging Mix)共转染293FT细胞,收集上清,纯化浓缩,测定重组病毒的滴度。取重组慢病毒感染hBMSCs,通过嘌呤霉素筛选并纯化hBMSCs,应用实时荧光定量PCR(quantitative PCR,qPCR)及ELISA法分别检测hBMSCs中IL-24mRNA及IL-24蛋白水平的表达情况。结果成功构建了共表达IL-24和EGFP基因的重组慢病毒载体,经包装、纯化及浓缩,病毒滴度为7.25×107PFU/mL。重组慢病毒转导hBMSCs后,通过筛选获得纯化,转导效率可达到100%。qPCR检测示:转导组IL-24mRNA表达明显高于未转导组(P<0.05);ELISA法检测显示转导组hBMSCs上清液IL-24蛋白表达40g/L,未转导组为阴性。结论构建的携带IL-24基因的重组慢病毒载体可有效转导hBMSCs,表达IL-24蛋白。展开更多
In this paper the topology of a four-leg shunt active-power filter (APF) is given. The APF compensates har-monic and reactive power in a three-phase four-wire system. The scheme adopted for control of the four-leg act...In this paper the topology of a four-leg shunt active-power filter (APF) is given. The APF compensates har-monic and reactive power in a three-phase four-wire system. The scheme adopted for control of the four-leg active power filter,a 3-Dimensional Pulse Width Modulation (PWM) technique,is presented. The theoretical deduction of a space vector PWM (SVPWM) algorithm is given in this paper. The paper also analyzes the distribution of the volt-age-space vector of the four-leg converter in αβγ coordinates and describes methods to determine the location of the voltage-space vector and to calculate duration time. Finally,the algorithm is implemented in simulation; the results show that the total harmonic distortion (THD) of the three phase-current waveforms is reduced. The neutral wire current,after compensation,is about 0 A showing that the topology of the four-leg shunt APF is feasible and the proposed scheme is effective.展开更多
文摘背景与目的以人骨髓间充质干细胞(human bone marrow mesenchymal stem cells,hBMSCs)作为抑癌基因IL-24的细胞载体的研究目前未见报道。应用Gateway法构建共表达增强型绿色荧光蛋白(enhanced green uorescentprotein,EGFP)基因和IL-24基因的慢病毒载体,探讨其对hBMSCs的转导情况,为今后肿瘤的基因治疗奠定基础。方法应用DNA重组技术构建含有IL-24和EGFP基因的慢病毒表达载体,并与慢病毒包装系统(ViraPowerTMLentiviralPackaging Mix)共转染293FT细胞,收集上清,纯化浓缩,测定重组病毒的滴度。取重组慢病毒感染hBMSCs,通过嘌呤霉素筛选并纯化hBMSCs,应用实时荧光定量PCR(quantitative PCR,qPCR)及ELISA法分别检测hBMSCs中IL-24mRNA及IL-24蛋白水平的表达情况。结果成功构建了共表达IL-24和EGFP基因的重组慢病毒载体,经包装、纯化及浓缩,病毒滴度为7.25×107PFU/mL。重组慢病毒转导hBMSCs后,通过筛选获得纯化,转导效率可达到100%。qPCR检测示:转导组IL-24mRNA表达明显高于未转导组(P<0.05);ELISA法检测显示转导组hBMSCs上清液IL-24蛋白表达40g/L,未转导组为阴性。结论构建的携带IL-24基因的重组慢病毒载体可有效转导hBMSCs,表达IL-24蛋白。
文摘In this paper the topology of a four-leg shunt active-power filter (APF) is given. The APF compensates har-monic and reactive power in a three-phase four-wire system. The scheme adopted for control of the four-leg active power filter,a 3-Dimensional Pulse Width Modulation (PWM) technique,is presented. The theoretical deduction of a space vector PWM (SVPWM) algorithm is given in this paper. The paper also analyzes the distribution of the volt-age-space vector of the four-leg converter in αβγ coordinates and describes methods to determine the location of the voltage-space vector and to calculate duration time. Finally,the algorithm is implemented in simulation; the results show that the total harmonic distortion (THD) of the three phase-current waveforms is reduced. The neutral wire current,after compensation,is about 0 A showing that the topology of the four-leg shunt APF is feasible and the proposed scheme is effective.
