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Xing Pei,Jiyoung Shin,김희정,Nana Wang,Chaewon Seo,Miyun Yoon,Xiongwen Chen,Jianqing Gao,Victor C. Yang,Huining He,Seungjin Lee 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.105 No.-
Stem cell-based therapeutic approach provides a possible treatment for critical limb ischemia (CLI) byinducing revascularization and regenerating ischemic tissue. However, the clinical benefit is modestdue to low cell survival and limited efficacy after transplantation. Cardiac-derived stem cells (CSCs) mightbe a novel cell source for CLI treatment owing to their superb endothelial differentiation potential andangiogenic paracrine functions. In this study, the angiogenic ability of CSCs was maximized by geneticengineering with constitutively active form of hypoxia-inducible factor-1a (CA-HIF-1a), resistant tooxygen-dependent degradation. CSCs transfected with CA-HIF-1a (CA-HIF-CSCs) promoted supplementaryexpression of proangiogenic factors including VEGF, bFGF, Ang-1 and PDGF-B, along with enhancedangiogenic function including migratory effect, tube formation and endothelial differentiation potential. In the mouse CLI model, CA-HIF-CSCs transplanted into the ischemic region using fibrin gel as cell deliveryvehicle, improved blood perfusion and limb functional recovery with minimal incidence of foot necrosisand limb loss by promoting new vessel formation. Histological evidence further confirmed that CAHIF-CSC/gel treatment markedly alleviated muscle degeneration and fibrosis. CSCs genetically engineeredwith constitutively active HIF-1a provide a novel therapeutic modality in CLI combining stem cell andgene therapy.
Empirical Study on Characteristics of Angled Spoke-Based Wheels on Granular Media
Kyungwook Lee,Sahoon Ahn,Kwan Yeong Yoo,ChaeWon Kim,TaeWon Seo 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
In this study, the optimal shape of angled spoke-based wheels (ASWs) was designed to maximize the driving speed of a mobile robot with ASWs on granular media. As a lightweight search and rescue mobile robot, it is required to have a high driving speed to reach the disaster site quickly. When granular media behave as fluids, slippage occurs, and the mobile robot slows down compared with when the media behave similarly to a solid ground. There are no exact criteria to explain the behavior of granular media. Therefore, the Taguchi method and L9(34) orthogonal array were employed to empirically optimize the shape of the ASW. The design variables evaluated were the motor RPM, width–height proportion of the foot, radius of curvature, and toe angle of the foot. The size of the ocher balls was adopted as the user condition. An orthogonal array and signal–to–noise (S/N) ratio were used to analyze the validity of the design variables. The optimal design variables of the ASW were a motor RPM of 6000, width–height proportion of 3:7, radius of curvature of 1.0×h, and toe angle of 15deg. Verification experiments were performed to evaluate the improved driving speed of the ASW. The angular velocity of the ASW increases by 2.79% for f1 (mm) and 10.50% for f6 (mm). Therefore, an optimized ASW de sign is expected to improve the driving speed of a mobile robot with ASWs.