集成电路引线键合机的最近发展概况

<正> 引线键合机是半导体组装工序中的典型设备。在过去十多年里,由于接受了高速化、省力化和小型化等许多要求,并采用了微型计算机和图象识别等最新技术,确实在发展和改造方面成绩显著。 作为其技术进步的结果,提高了集成电路的生产效率,实现了组装过程的省力化,减少了建造代价昂贵的净化厂房面积。因而     

SAD phasing by OASIS at different resolutions down to 0.30 nm and below

Single-wavelength anomalous diffraction （SAD） phasing is increasingly important in solving de novo protein structures. Direct methods have been proved very efficient in SAD phasing. This paper aims at probing the low-resolution limit of direct-method SAD phasing. Two known proteins TT0570 and Tom70p were used as test samples. Sulfur-SAD data of the protein TT0570 were collected with conventional Cu-Kα source at 0.18 nm resolution. Its truncated subsets respectively at 0.21, 0.30, 0.35 and 0.40 nm resolutions were used in the test. TT0570 Cu-Kα sulfur-SAD data have an expected Bijvoet ratio 〈 ｜△F｜ 〉 / 〈 F 〉 ～ 0.55%. In the 0.21 nm case, a single run of OASIS-DM-ARP/wARP led automatically to a model containing 1178 of the total 1206 residues all docked into the sequence. In 0.30 and 0.35 nm cases, SAD phasing by OASIS-DM led to traceable electron density maps. In the 0.40 nm case, SAD phasing by OASIS-DM resulted in a degraded electron density map, which may be difficult to trace but still contains useful secondary-structure information. Test on real 0.33 nm selenium-SAD data of the protein Tom70p showed that even automatic model building was not successful, the combination of manual tracing and direct-method fragment extension was capable of significantly improving the electron-density map. This provides the possibility of effectively improving the manually built model before structure refinement is performed.     

Rogers LS3/5A60周年纪念版探秘

多家厂商获得英国BBC公司的许可生产 这是一款1970年代诞生的英国BBC规格的小型鉴听音箱。Rogers公司诞生于20世纪的1946年,创始人是Jim Rogers,初创时期公司名称是Rogers Development（Electronics）LTD。