- Home
- Seminar
Seminar on Mechanical Science and Bioengineering
|
200th
|
July 19, 2024 15:00-16:00 Seminar Room, Engineering Science International Building |
|---|---|
| Thermodynamic and mechanical stability of multi-principal elemental alloys: The role of chemical short-range order | |
| In the past two decades, materials science has witnessed a remarkable breakthrough with the introduction of multiple principal elements into a single-phase crystal, leading to a conceptual revolution in physical metallurgy known as multi-principal elemental alloys (MPEAs). These alloys exhibit a unique characteristic where chemical short-range order (CSRO) is formed due to the competition between enthalpic and entropy interactions. However, the underlying physical mechanism behind the thermodynamic and mechanical stability of such alloys, especially the formation mechanism of CSRO remains incompletely understood, and its impact on the mechanical properties of MPEAs is still being explored. In this presentation, I will elucidate the process of chemical disorder-order transition in solid solutions by examining the absolute free energy of the alloy configuration. Through atomistic simulations, I will discuss the role of SRO in phonon instability, diffusion, and dislocation plasticity. Furthermore, I will emphasize the significance of vibrational and configurational entropy in comprehending the thermodynamic stability and deformation mechanisms of MPEAs. | |
|
Dr. Yun-Jiang Wang
Institute of Mechanics, Chinese Academy of Sciences |
|
|
199th
|
July 16, 2024 12:00-13:00 Room C419 |
| ECM-mediated EndMT in vascular wall remodeling | |
| Endothelial-to-mesenchymal transition (EndMT) is a fundamental process in vascular remodeling, which involves functional changes in both cells and extracellular matrix (ECM) in response to various stimuli. EndMT has been implicated in the pathogenesis of cardiovascular pathologies, however the details of its regulatory mechanism remain unclear. We have previously shown that EndMT is the main cause of neointima formation in vascular stenosis upon carotid artery ligation, and that hypoxic conditions associated with blood flow arrest trigger EndMT and neointima formation (Yamashiro. Cardiovasc. Res., 2023). However, how does EndMT initiate in a hypoxic environment? The details of the pathogenic mechanism have not been clarified. Therefore, using human aortic endothelial cells (HAEC), we clarified the genes whose expression increases or decreases under hypoxic conditions by RNA-seq analysis. We also identified the ECM protein, Angiopoietin-like 4 (ANGPTL4), which is secreted from HAECs under hypoxic conditions, by secretome analysis. The mRNA expression at the single-cell resolution by spatial transcriptomics (HybISS) and the analysis of ECM dynamics using timelapse-live imaging techniques will reveal the details of the mechanism of EndMT onset. | |
|
Dr. Yoshito Yamashiro
Laboratory Chief (Team Leader), Department of Advanced Technologies, National Cerebral and Cardiovascular Center, Research Institute |
|
|
198th
|
July 4, 2024 15:00-16:00 Seminar Room J114, Engineering Science International Building |
| Molecular dynamics and enhanced energy landscape sampling investigations on defect evolution in crystalline metals | |
| The evolutions of crystalline defects as responses to external thermo-mechanical stimuli are responsible for the properties of structural materials at different spatial/temporal scales. Molecular dynamics simulation enables us to follow such atomic-level processes with its predictive power, and this power can be enhanced by probing the complex energy landscape via the Activation-Relaxation Technique or other Metadynamics-based algorithms. With these approaches, explorations on defect evolutions including both interface behaviors and dislocation behaviors were made, to elucidate some controversial topics or to constitute a more comprehensive mechanism map, with a particular attention paid to hexagonal close-packed metals. | |
|
Dr. Xiao-Zhi Tang
Associate Professor, Department of Mechanics, School of Physical Science and Engineering, Beijing Jiaotong University |
