U71Mn 起重机轨道焊接工艺

由于起重机轨道通常采用高碳中锰的U71Mn钢轧制而成,焊接性能较差,焊缝中容易产生裂纹、夹渣等缺陷;同时由于轨道截面的特殊性,轨道焊接易产生挠曲变形。文章进行了U71Mn钢的焊接性能分析,分析了轨道焊接常见问题和产生原因,提出了控制措施,并详细介绍了U71Mn钢轨道焊接的施工工艺,对同类钢轨焊接具有借鉴意义。     

肠道病毒71型吉林分离株的全基因组序列分析

目的对2011年吉林省肠道病毒71型(enterovirus type 71,EV71)分离株全基因组进行序列分析。方法将手足口病伴发重症脑炎患者的粪便样品接种至Vero细胞,分离EV71;采用RT-PCR法分8段扩增全基因组序列,进行双酶切及序列测定;应用Mega5软件构建EV71系统进化树;通过DNAMAN7和DNASTAR7软件进行EV71分离株核苷酸和氨基酸序列的同源性比较;经RDP4软件对EV71分离株进行同源重组分析。结果粪便样品接种至Vero细胞2 d后,细胞出现圆缩、透亮、聚堆的病变现象;各PCR扩增产物经双酶切鉴定,均可见与预期大小一致的目的条带;经种系进化树分析显示,EV71分离株属C4a亚型,命名为EV71-JiLin-11-China;其与A、B和C亚型间核苷酸序列的平均同源性分别为22.44%、17.72%和11.96%,与A、B和C亚型间氨基酸序列的平均同源性分别为96.0%、97.2%和97.3%;全基因同源重组分析显示,EV71分离株的165～1 946和7 289～7 366核苷酸区有重组现象,分别源于分离自湖北的C4a-EV71-Hubei-09-China及马来西亚的B4-SB2864-SAR-00和C1-S18062-SAR-98。结论 2011年吉林地区流行的EV71为C4a基因型,为EV71基因特征及流行病学的研究提供了实验依据。     

高速大容量 SRAM IDT71V3558 的原理及应用

IDT71V3558是IDT公司新推出的一种高速、大容量的TTL同步静态存储器(SRAM) ,利用它可以对大容量数据进行高速缓存。文中介绍了该芯片的结构和原理 ,同时给出了一个可满足通信过程中大容量、高速数据传输要求的设计方案。     

The political side of public utilities: How opportunistic behaviour and yardstick competition shape water prices in Austria

This paper studies the effect of politics on water prices in Austria. When public utilities are under political control, price setting may be affected by political incentives. Besides theories like the political budget cycle, more current research stresses the role of spatial interactions between jurisdictions (yardstick competition). The paper tests for both local political determinants and yardstick competition using a spatial lag model. The results suggest that water prices are lower when political competition is strong and before elections. At the same time the magnitude of the political budget cycle appears to depend upon neighbouring jurisdictions, thus confirming yardstick competition as an indirect determinant of water prices.     

“华中”系统数控车削G71指令的编程技巧

在数控编程和数控实训教学过程中从学生应用G71指令经常出现错误问题出发，探讨了G71指令在编程中的技巧，力求通过建立的编程模板，让学生能够准确应用G71指令，保证了零件加工的尺寸精度（加工精度）和安全问题。     

肠道病毒71型P1和3CD基因双顺反子重组腺病毒的构建及表达

目的构建肠道病毒71型(EV71)P1和3CD基因双顺反子重组腺病毒,并检测3CD蛋白酶的切割作用和表达产物的抗原性。方法采用RT-PCR法从阜阳分离的EV71中扩增P1和3CD基因,构建穿梭质粒pShuttle-CMV-P1-3CD、pShuttle-CMV-P1和pShuttle-CMV-3CD;经同源重组获得重组腺病毒rAd-P1-3CD、rAd-P1和rAd-3CD,分别转染293细胞,RT-PCR法检测目的基因的转录,免疫荧光法检测目的蛋白的表达。结果3种重组腺病毒经PCR和酶切鉴定表明构建正确;RT-PCR检测表明,3个重组腺病毒均已转录目的基因mRNA;免疫荧光检测仅观察到rAd-P1-3CD表达产物具有特异性,而rAd-P1、rAd-3CD未能检测到特异性表达产物。结论已成功构建EV71P1和3CD基因双顺反子重组腺病毒,表达产物具有EV71特异抗原性,提示P1产物只有在被3CD蛋白酶切割后才体现抗原性。     

Kaempferol inhibits enterovirus 71 replication and internal ribosome entry site (IRES) activity through FUBP and HNRP proteins

Flavonoids are associated with multiple biological and pharmacological activities, including anti-enterovirus activity. An internal ribosomal entry site (IRES) required for viral protein translation is a potential drug target for enterovirus 71 (EV71). Regulation translation initiation requires the interaction of IRES specific trans-acting host factors with viral IRES element. By evaluation of 12 flavonoids against EV71 infection, we found that (a) 7,8-dihydroxyflavone, kaempferol, quercetin, hesperetin and hesperidin exhibited more than 80% of cell survival and inhibition of EV71 infection; however, no anti-oxidative effects were noted from these flavonoids; (b) among them, only 7,8-dihydroxyflavone, kaempferol and hesperetin showed 40% of viral IRES activity; (c) kaempferol interfered with EV71 virus replication and pseudotyped virus production; and (d) FUBP1, FUBP3, HNRPD, HNRH1 and HNRPF proteins are associated with EV71 5′-UTR as shown using RNA affinity pull-down assay coupled with LC–MS/MS analysis. We firstly found that kaempferol may change the composition of these IRES associated trans-acting factors, and affect IRES function and EV71 virus replication. These studies help not only to understand the IRES function but also the mechanism by which drug induced cellular proteins are acting against EV71 infection.     

G71与G70指令使用中应注意的几个问题

G71与G70指令是二个复合固定循环指令,在机械零件加工制造中常用于形状复杂的阶梯轴零件的编程与加工。但是要正确使用这二个指令还需要注意一些问题,才能取得理想的加工效果。     

一种新式发爆器的研制及应用

根据国内现使用各类发爆器的情况,在原普通电容式发爆器的基础上,为完善FB-100型袖珍多功能发爆器,经过研究小组的共同努力,研制出了FD-100Z自动检查爆破网路电阻数码电容式发爆器。该发爆器具有网路全电阻值检查、操作简单、指示明确、性能稳定、造型美观、体积小、质量轻、工作时用电量小,有导通和电源指示等功能。已获国家专利。     

基于结晶收缩特性的连铸矩形坯成形曲线研究

针对传统连铸结晶器效率低、拉坯速度慢、铸坯表面及形状缺陷等问题,设计并加工了一种高效、高速、高质(Efficient,speedy and quality, ESQ)连铸结晶器内腔形线。基于矩形坯结晶器内传热和结晶收缩行为特性,推导并建立了结晶器铜管内腔形线几何模型,运算得到形线曲线表达式和锥度表达式。根据连铸坯热交换收缩组成模型,针对高碳钢材料大矩形坯规格修正原模型及表达式,将优化结果与钢厂传统形线对比分析。依托Matlab/GUI二次开发了结晶器形线尺寸输出系统,为现有钢厂设计并加工了230 mm×170 mm断面U71Mn钢种结晶器芯棒和铜管,保持其他连铸条件基本不变,使现有连铸机拉坯速度从1.1 m/min提高至1.6～1.7 m/min。结果表明,得到的连铸坯产品表面质量与原产品相近,且并无形状缺陷,验证了模型计算的合理性和正确性。相比于传统连铸结晶器内腔形线,新形线曲线提高了结晶器的换热效率,且保证了铸坯质量,这为增加连铸坯产量提供了基础。