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316L stainless steel materials are widely used in impact-resistant structures. Heat treatments could affect the mechanical properties of 316L stainless steel parts formed by selective laser melting (SLM), which is vital for ensuring service safety. This study aimed to analyze the mechanical behavior of SLM 316L stainless steel under different heat treatment methods. Therefore, test specimens were prepared using the SLM technique and then annealed at 400°C for 1 h. The solution was treated at 1050°C for 20 min. The dynamic compressive mechanical properties of the deposited, annealed, and solution-treated specimens were tested at high strain rates by using a split Hopkinson pressure bar (SHPB) experimental apparatus. Moreover, the microstructures of the previously mentioned samples were analyzed by optical microscopy and scanning electron microscopy. The experimental results showed that the three-state samples exhibited strain rate sensitivity in the dynamic mechanical tests and that solution treatment could alter their mechanical properties significantly. In addition, the microstructure of the deposited specimens presented cylindrical cellular crystal features, which have a higher dislocation density. Hence, the yield strength of deposited specimens is higher than that of the solution-treated ones. After annealing, the microstructures of the samples did not change obviously, and their dynamic yield strength remained almost unchanged. After solution treatment, its cellular crystal disappeared and dislocation density dropped dramatically, resulting in a sharp decrease in yield strength. Finally, this research can provide a theoretical reference for broadening the practical application of SLM 316L material parts. [ABSTRACT FROM AUTHOR]

Oxidase-catalyzed kinetic resolution is important for the production of enantiopure 2-hydroxycarboxylic acids (2-HAs), which are versatile building blocks for the synthesis of many significant compounds. However, in contrast to that of ( R)-2-HAs, the production of ( S)-2-HA is challenging because of the lack of related oxidases. Herein, suitable enzymes were screened systematically through the analysis of numerous putative d-lactate oxidase sequences and identification of several required properties. Finally, a d-lactate oxidase from Gluconobacter oxydans 621H with advantageous characteristics, such as good solubility, broad substrate spectrum, and high stereoselectivity, was selected to resolve 2-HAs into ( S)-2-HAs. A variety of ( S)-2-HAs was produced successfully using this d-lactate oxidase with excellent enantiomeric excess values (>99 %). The presented screening criteria and approach for target biocatalysis suggested a guideline for the production of optically active chemicals such as ( S)-2-HAs. [ABSTRACT FROM AUTHOR]

Background: The in-depth understanding of the fine anatomy of the liver has promoted the development of modern liver surgery. With the rapid popularity of laparoscopic hepatectomy, the membrane structure of the liver and its ability to dissect the intrahepatic and extrahepatic vascular system more conveniently and accurately has been gradually emphasized., Objective: Exploring the value of extrahepatic sheath dissection of the hepatic pedicle in minimally invasive anatomical hepatectomy with cystic plate approach. This study aims to assess the benefits of integrating the cystic plate approach with real-time guided laparoscopic anatomical hepatectomy, in comparison with conventional laparoscopic anatomical hepatectomy., Materials and Methods: Based on the theory of cystic plate and hepatic portal plate, the authors have pioneered the fluorescence real-time guided cystic plate approach in hepatectomy. The article focuses on the anatomical knowledge and technical difficulties of anatomical hepatectomy with fluoroscopic laparoscopic cystic plate approach and explores the safety and practicality of the cystic plate approach in laparoscopic anatomical hepatectomy. Additionally, a retrospective cohort study was also conducted to compare the operation time, intraoperative blood loss, and postoperative complications between the cystic plate approach and the conventional approach during fluoroscopic laparoscopic hepatectomy., Results: A total of 38 patients who met the inclusion criteria underwent laparoscopic hepatectomy between January 2019 and November 2022. No significant disadvantages were found in terms of operation time and intraoperative blood loss during the surgeries. Furthermore, the postoperative indications, including liver function indexes on the first postoperative day, WBC, and the postoperative hospital stay, were also not affected, thus proving the safety of the cystic approach. Importantly, through the cystic plate approach, the target liver pedicle was fully freed, and then the segments to be resected were precisely marked by positive or negative staining, followed by hepatectomy under real-time fluoroscopic guidance. This approach is extremely advantageous in anatomical liver segment resections, especially in right posterior lobe or hemi-hepatectomy, without increasing intraoperative bleeding or postoperative complication rates., Conclusion: This technique allows for easy and safe freeing of the target liver pedicle using membrane structures, and also allows for precise anatomical hepatectomy in combination with real-time fluoroscopic laparoscopic navigation., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)