Abstract: A tunable fixation device for fixation of heart valve leaflets includes a central assembly, an arm moveably coupled to the central assembly, and a gripping element moveable relative to the arm to capture a native leaflet therebetween. The arm has a body portion and a wire frame coupled to the body portion. The wire frame has a first and second wire segment, and an interconnection portion interconnecting the first and second wire segments. The interconnection portion is slidingly engaged with the body portion. The first wire segment is configured to deform upon force applied to the second wire segment by sliding movement of the interconnection portion relative to the body portion, and the second wire segment is configured to deform upon force applied to the first wire segment by sliding movement of the interconnection portion relative to the body portion.

Abstract: A control process of inclusions in ultra-clean rare earth steel, wherein the content of rare earth elements REM in the ultra-clean rare earth steel, the total oxygen content T[O]m, the total sulfur content T[S]m in the steel, and the total oxygen content T[O]r in a rare earth metal or alloy added to the steel are controlled to satisfy the following formula: ?500<REM?(m*T[O]m+n*T[O]r+k*T[S]m)<?30, where REM is the content of rare earth elements in the steel, in ppm; T[O]m is the total oxygen content in the steel, in ppm; T[O]r is the total oxygen content in a rare earth metal or alloy added to the steel, in ppm; T[S]m is the total sulfur content in the steel, in ppm; m is a first correction coefficient, with a value of 2-4.5;n is a second correction coefficient; and k is a third correction coefficient.

Abstract: Provided in the present application are a rare-earth microalloyed steel and a control process. The steel has a special microstructure, and the microstructure comprises a rare earth-rich nanocluster having a diameter of 1-50 nm. The nanocluster has the same crystal structure type as a matrix. The rare earth-rich nanocluster inhibits the segregation of the elements S, P and As on a grain boundary, and obviously improves the fatigue life of the steel. In addition, a rare-earth solid solution also directly affects a phase change dynamics process so that the diffusion-type phase change starting temperature in the steel changes at least to 2° C., and even changes to 40-60° C. in some kinds of steel, thereby greatly improving the mechanical properties thereof, and providing a foundation for the development of more kinds of high-performance steel.

Abstract: Provided in the present application are a rare-earth microalloyed steel and a control process. The steel has a special microstructure, and the microstructure comprises a rare earth-rich nanocluster having a diameter of 1-50 nm. The nanocluster has the same crystal structure type as a matrix. The rare earth-rich nanocluster inhibits the segregation of the elements S, P and As on a grain boundary, and obviously improves the fatigue life of the steel. In addition, a rare-earth solid solution also directly affects a phase change dynamics process so that the diffusion-type phase change starting temperature in the steel changes at least to 2° C., and even changes to 40-60° C. in some kinds of steel, thereby greatly improving the mechanical properties thereof, and providing a foundation for the development of more kinds of high-performance steel.

Abstract: Provided are an ultra-clean rare earth steel and an occluded foreign substance modification control method, the steel includes 10-200 ppm of rare earth elements, 50% or more occluded foreign substances in the steel are dispersed into RE-oxygen-sulfide with the average equivalent diameter Dmean ranging from 1-5 ?m in a spherical shape or a substantially spherical shape or a granular shape; according to the method, at least 80%, preferably at least 90%, of Al2O3 occluded foreign substances in the steel are modified into RE-oxygen-sulfide, compared with steel with the same components without rare earth, the total amount of the occluded foreign substances in the steel is reduced by 18% or higher, the cracking probability caused by occluded foreign substances such as Al2O3 in traditional pure steel is reduced, the mechanical performance such as the fatigue life of the steel is remarkably improved.