Structure and Properties of Cast Ti-Al-Si Alloys

Intermetallic compounds based on Ti-Al- (Si) are attractive materials with good thermal stability and low density. However, the production of these materials is quite complicated. Partially modified conventional methods of melting metallurgy are most often used due to availability, possible high productivity, and relatively low production costs. Therefore, some technologies for the production of intermetallics based on Ti-Al are currently available, but with certain disadvantages, which are caused by poor casting properties or extreme reactivity of the melt with crucibles. Some shortcomings can be eliminated by modifying the melting technology, which contributes to increasing the cost of the process. The work deals with the preparation of Ti-Al-Si intermetallic compounds with different contents of aluminum and silicon, which were produced by centrifugal casting in an induction vacuum furnace Linn Supercast-Titan. This process could contribute to the commercial use of these alloys in the future. For this research, the TiAl15Si15(in wt.%) alloy was selected, which represents a balanced ratio of aluminides and silicides in its structure, and the TiAl35Si5 alloy, which due to the lower silicon content allows better melting conditions, especially with regard to the melting temperature. This alloy was also investigated after HIP (“Hot Isostatic Pressing”) treatment.     

Quality-of-Life Research in Acne Vulgaris: Current Status and Future Directions

American Journal of Clinical Dermatology - Acne patients may have significant quality-of-life (QoL) impairment, therefore assessment of health-related QoL (HRQoL) in acne patients is recommended by...     

Synthetic Cannabinoid Intoxication Presenting as Malignant Catatonia: a Case Report

International Journal of Mental Health and Addiction - The use of synthetic cannabinoids (SCs) has been steadily increasing in recent years and represents a new class of substances of abuse....     

Double S-Curve Versus Cusp-Overlap Technique: Defining the Optimal Fluoroscopic Projection for TAVR With a Self-Expanding Device

ObjectivesThe purpose of this study was to assess the concordance between transcatheter aortic valve implantation angles generated by the “double S-curve” and “cusp-overlap” techniques.BackgroundThe “double S-curve” and “cusp-overlap” methods aim to define optimal fluoroscopic projections for transcatheter aortic valve replacement (TAVR) with a self-expandable device.MethodsThe study included 100 consecutive patients undergoing TAVR with self-expanding device planned by multidetector computed tomography. TAVR was performed using the double S-curve model, as a view in which both the aortic valve annulus and delivery catheter planes are displayed perpendicularly on fluoroscopy. Optimal projection according to the cusp-overlap technique was retrospectively generated by overlapping the right and left cups on the multidetector computed tomography annular plane. The angular difference between methods was assessed in spherical 3 dimensions and on the left and right anterior oblique (RAO) and cranial and caudal (CAU) axes.ResultsThe double S-curve and cusp-overlap methods provided views located in the same quadrant, mostly the RAO and CAU, in 92% of patients with a median 3-dimensional angular difference of 10.0° (interquartile range: 5.5° to 17.9°). The 3-dimensional deviation between the average angulation obtained by each method was not statistically significant (1.49°; p = 0.349). No significant differences in average coordinates were noted between the double S-curve and cusp-overlap methods (RAO: 14.7 ± 15.2 vs. 12.9 ± 12.5; p = 0.36; and CAU: 27.0 ± 9.4 vs. 26.9 ± 10.4; p = 0.90). TAVR using the double S-curve was associated with 98% device success, low complication rate, and absence of moderate-to-severe paravalvular leak.ConclusionsThe double S-curve and cusp-overlap methods provide comparable TAVR projections, mostly RAO and CAU. TAVR using the double S-curve model is associated with a high rate of device success and low rate of procedural complications.