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595 results on '"Li, Muzi"'

10. Bioabsorbable WE43 Mg alloy wires modified by continuous plasma-electrolytic oxidation for implant applications. Part I: processing, microstructure and mechanical properties

Author

Ali, Wahaaj, Li, Muzi, Tillmann, Leon, Mayer, Tim, González, Carlos, LLorca, Javier, and Kopp, Alexander

Subjects
Physics - Medical Physics, Condensed Matter - Materials Science
Abstract

In our work, a novel processing strategy for the continuous fabrication and surface modification of wires from Magnesium alloy WE43 by means of plasma-electrolytic oxidation (PEO) is presented. In the first step, wires with a strong basal texture and small grain size ($\approx$ 1 $\mu$m) were manufactured by combined cold drawing and in-line stress-relief heat treatment steps that optimized the mechanical properties (in terms of strength and ductility) by means of annealing. In a second step, and to the best of our knowledge for the first time ever, the wires were continuously surface-modified with a novel plasma electrolytic oxidation process, which was able to create a homogeneous porous oxide layer made of MgO and Mg$_3$(PO4)$_2$ on the wire surface. While the oxide layer slightly diminished the tensile properties, the strength of the surface-modified wires could be maintained close to 300 MPa with a strain-to-failure $\approx$ 8\%. Furthermore, the thickness of the oxide layer could be controlled by immersion time within the electrolytic bath and was adjusted to realize a thicknesses of $\approx$ 8 $\mu$m, which could be obtained in $<$ 20 s. Our experiments showed that the chemical composition, morphology and porosity of the oxide layer could be tailored by changing electrical parameters. The combined cold drawing and heat treatment process with additional continuous plasma electrolytic oxidation processing can be upscaled to produce a novel generation of bioabsorbable Mg wires with optimized mechanical, degradation and biological performance for use in biomedical applications.

Published
2023

11. The von Zeipel-Lidov-Kozai effect inside mean motion resonances with applications to trans-Neptunian objects

Author

Lei, Hanlun, Li, Jian, Huang, Xiumin, and Li, Muzi

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Secular dynamics inside MMRs plays an essential role in governing the dynamical structure of the trans-Neptunian region and sculpting the orbital distribution of trans-Neptunian objects (TNOs). In this study, semi-analytical developments are made to explore the von Zeipel-Lidov-Kozai (ZLK) resonance inside mean motion resonances (MMRs). To this end, a semi-secular model is formulated by averaging theory and then a single-degree-of-freedom integrable model is achieved based on the adiabatic invariance approximation. In particular, we introduce a modified adiabatic invariant, which is continuous around the separatrices of MMRs. During the long-term evolution, both the resonant Hamiltonian and the adiabatic invariant remain unchanged, thus phase portraits can be produced by plotting level curves of the adiabatic invariant with given Hamiltonian. The phase portraits provide global pictures to predict long-term behaviors of the eccentricity, inclination and argument of pericenter. Applications to some representative TNOs inside MMRs (2018 VO137, 2005 SD278, 2015 PD312, Pluto, 2004 HA79, 1996 TR66 and 2014 SR373) show good agreements between the numerically propagated trajectories under the full N-body model and the level curves arising in phase portraits. Interestingly, 2018 VO137 and 2005 SD278 exhibit switching behaviors during the long-term evolution and currently they are inside 2:5 MMR with Neptune., Comment: 17 pages, 11 figures. Accepted for publication in AJ

Published
2022
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21. Simulation of corrosion and mechanical degradation of additively manufactured Mg scaffolds in simulated body fluid

Author

Marvi-Mashhadi, Mohammad, Ali, Wahaaj, Li, Muzi, González, Carlos, and LLorca, Javier

Subjects
Physics - Applied Physics, Condensed Matter - Materials Science
Abstract

A simulation strategy based in the finite element model was developed to model the corrosion and mechanical properties of biodegradable Mg scaffolds manufactured by laser power bed fusion after immersion in simulated body fluid. Corrosion was simulated through a phenomenological, diffusion-based model which can take into account pitting. The elements in which the concentration of Mg was below a certain threshold (representative of the formation of Mg(OH)2) after the corrosion simulation were deleted for the mechanical simulations, in which Mg was assumed to behave as an isotropic, elastic-perfectly plastic solid and fracture was introduced through a ductile failure model. The parameters of the models were obtained from previous experimental results and the numerical predictions of the strength and fracture mechanisms of WE43 Mg alloy porous scaffolds in the as-printed condition and after immersion in simulated body fluid were in good agreement with the experimental results. Thus, the simulation strategy is able to assess the effect of corrosion on the mechanical behavior of biodegradable scaffolds, which is critical for design of biodegradable scaffolds for biomedical applications.

Published
2021

25. The application of large language models in medicine: A scoping review

Author

Meng, Xiangbin, Yan, Xiangyu, Zhang, Kuo, Liu, Da, Cui, Xiaojuan, Yang, Yaodong, Zhang, Muhan, Cao, Chunxia, Wang, Jingjia, Wang, Xuliang, Gao, Jun, Wang, Yuan-Geng-Shuo, Ji, Jia-ming, Qiu, Zifeng, Li, Muzi, Qian, Cheng, Guo, Tianze, Ma, Shuangquan, Wang, Zeying, Guo, Zexuan, Lei, Youlan, Shao, Chunli, Wang, Wenyao, Fan, Haojun, and Tang, Yi-Da

Published
2024
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42. Study of the Redox Potentials of Benzoquinone and Its Derivatives by Combining Electrochemistry and Computational Chemistry

Author

Ji, Xuan, Liu, Xiaomei, Li, Muzi, Shao, Songxue, Chang, Jing, Du, Jing, Ma, Xiaofei, Feng, Xia, Zhu, Lina, Yu, Xi, and Hu, Wenping

Abstract

As simple and ubiquitous redox-active organic molecules, quinones participate in diverse electron transfer processes in chemistry and biological systems for energy transformation and signal transduction. We introduce here a practical exercise to study the redox potentials of benzoquinone and its two derivatives by combining the electrochemistry method with quantum chemistry computation. The practical reduction potentials of three quinones were measured by cyclic voltammetry experiment. Quantum chemistry computation, on the other hand, provided theoretical Gibbs free energy change and reduction potentials of the three quinones, which were found to be in line with the experimental results. Detailed thermodynamic energy analysis based on the computation results revealed that the reduction Gibbs free energy changes of the three quinones were mainly contributed from the electronic energies change of the molecules, while thermal energy and entropy played a relatively minor role. The energy levels of the lowest unoccupied molecular orbital (LUMO) of the three quinones, which were modulated by substituent groups and conjugation structures, were further identified as the main origin of the reduction potential. This experiment provides practical and theoretical training on the fundamental ideas involved in major courses like thermodynamics, quantum chemistry, electrochemistry, and organic chemistry, and promotes students to find the tie between macroscopic redox properties of chemicals and their microscopic molecular structures, a key topic in chemistry education.

Published
2021
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