19mm和21mm St.Jude主动脉瓣膜置换术后长期随访结果比较

应用小直径人造心脏瓣膜行主动脉瓣置换术后可能会导致左心室流出道残余梗阻,引起心肌肥厚,妨碍术后病情康复,并有可能影响术后长期生存率。该文对229例置换19mm或21mm标准St.Jude瓣膜的患者进行了近15年的长期临床随访、研究。

Hot-rolled strips of up to 19 mm in thickness and their processing to helically welded large diameter pipes of grade X80

Hot-rolled wide strip for production of large diameter,heavy gauged(up to 19 mm) helical line pipe grade X80 was a priority development over the last three years.Microstructure,texture and mechanical properties of strips have been characterised.Also the welding conditions have been simulated.The favourable microstructure is achieved by the proper selection of an appropriate chemical composition of low carbon content and increased niobium micro alloying in combination with suitable strictly controlled hot-rolling parameters.The addition of niobium in combination with the adjustment of other alloying elements increases the recrystallisation stop temperature and thus makes it possible to apply a high temperature processing(HTP) concept.The homogeneous bainitic microstructure across the strip gauge is then formed during accelerated cooling on the run-out table of the hot-rolling mill.All results indicated excellent properties of these hot strips which make it suitable for spiral pipes of grade X80 for example 18.9mm×Φ1 220 mm at dimension.

全自动盘料铜管单根校直无屑下料机的研究与设计

全自动盘料铜管单根校直无屑下料机是将盘料紫铜管校直切断成定尺直管的专用设备。该机通过更换校直轮、夹紧模具、切刀滑块、托轮滑块即可加工不同管径不同壁厚的铜管,特别适用于多品种、小批量产品,该机主要由主动开料盘料架、校直机构、夹紧送料装置、切断装置、拉断装置、接料架等组成。该机使紫铜管由盘料切割成定尺直料的过程全部实现了自动化,主动力来源于气动系统。该机为割刀无屑切割,并且通过更换零件具有切割从Φ(6.35～19)mm之间任何一种外径铜管的功能(更换时间只需5min)。该机具有自动操作和手动操作两种操作方法。