LPBF and Post Processing of H13 Tool Steel

Laser powder bed fusion (LPBF) is an innovative method where metal powder is fused together to generate complex geometries. LPBF is used as a technology to reduce material waste, and extensive labor that are often linked to conventional subtractive manufacturing. H13 tool steel is one of the widely used materials in several industries and has, therefore, gained interest in the additive manufacturing field due to its excellent mechanical properties. To produce H13 parts with optimal mechanical properties, printing parameters are optimized and a high relative density of 98% is obtained. Laser power of 203W, scanning speed of 700 mm/s, hatch spacing of 40μm and layer thickness of 25 μm are used to obtain the optimal results. Hot isostatic pressing is applied to cure the microcracks and has shown a 0.5% increase in the relative density, while it showed a significant decrease in other samples due to the excessive residual heat. Optical and scanning electron microscopy are used to observe the recrystallization of grains and grain growth resulted by tempering and rapid cooling. Tempering temperatures of 650˚C resulted in a greater reduction of microhardness than 550 ˚C. While high hot isostatic pressing temperature (1163 ˚C) shows a worsening effect on the microstructures

Prevalence of CYP2C19*2 carriers in Saudi ischemic stroke patients and the suitability of using genotyping to guide antiplatelet therapy in a university hospital setup

OBJECTIVES: To mitigate the incidence of recurrent stroke in patients, dual antiplatelet therapy comprising aspirin and clopidogrel is usually administered. Clopidogrel is a prodrug and its bioactivation is catalyzed by cytochrome P450 (CYP)2C19. The main objective of this work was to determine the prevalence of CYP2C19*2 carriers in Saudi ischemic stroke patients and assess the suitability of using genotyping to guide antiplatelet therapy in a university hospital setup. METHODS: This prospective (2018-2019) study was conducted on 256 patients (age 61 ± 12.5) clinically diagnosed with ischemic stroke who were genotyped using Spartan RX CYP2C19 assay. RESULTS: From the total patient group (256), upon admission, 210 patients were prescribed either aspirin, clopidogrel or dual antiplatelet therapy. Of the 27 patients with the CYP2C19*2 allele who were prescribed clopidogrel (18) or dual antiplatelet therapy (9), only 21 patients could be followed up for a period of six months post stroke event, in addition to 21 age- and sex-matched patients with the normal allele. The CYP2C19*2 allele carriers had a statistically significant increased risk of recurrent stroke compared to patients carrying the normal allele. CONCLUSIONS: This study shows the suitability of using genotyping to guide antiplatelet therapy in ischemic stroke patients in a clinical setting