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The Nrf2 antioxidant defense system in intervertebral disc degeneration: Molecular insights
Xiang Qian,Zhao Yongzhao,Lin Jialiang,Jiang Shuai,Li Weishi 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-
Intervertebral disc degeneration (IDD) is a common degenerative musculoskeletal disorder and is recognized as a major contributor to discogenic lower back pain. However, the molecular mechanisms underlying IDD remain unclear, and therapeutic strategies for IDD are currently limited. Oxidative stress plays pivotal roles in the pathogenesis and progression of many age-related diseases in humans, including IDD. Nuclear factor E2-related factor 2 (Nrf2) is a master antioxidant transcription factor that protects cells against oxidative stress damage. Nrf2 is negatively modulated by Kelch-like ECH-associated protein 1 (Keap1) and exerts important effects on IDD progression. Accumulating evidence has revealed that Nrf2 can facilitate the transcription of downstream antioxidant genes in disc cells by binding to antioxidant response elements (AREs) in promoter regions, including heme oxygenase-1 (HO-1), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and NADPH quinone dehydrogenase 1 (NQO1). The Nrf2 antioxidant defense system regulates cell apoptosis, senescence, extracellular matrix (ECM) metabolism, the inflammatory response of the nucleus pulposus (NP), and calcification of the cartilaginous endplates (EP) in IDD. In this review, we aim to discuss the current knowledge on the roles of Nrf2 in IDD systematically.
Xiangqian Shen,Tong Li,Lei Xu,Faraz Kiarasi,Masoud Babaei,Kamran Asemi Techno-Press 2024 Advances in nano research Vol.16 No.1
In this study, free vibration analysis of FG porous spherical cap reinforced by graphene platelets resting on Winkler-type elastic foundation has been surveyed for the first time. Three different types of porosity patterns are considered for the spherical cap whose two types of porosity patterns in the metal matrix are symmetric and the other one is uniform. Besides, five GPL patterns are assumed for dispersing of GPLs in the metal matrix. Tsai-Halpin and extended rule of the mixture are used to determine the Young modulus and mass density of the shell, respectively. Employing 3D FEM elasticity in conjunction with Hamilton's Principle, the governing motion equations of the structure are obtained and solved. The impact of various parameters including porosity coefficient, various porosity distributions in conjunction with different GPL patterns, the weight fraction of graphene Nano fillers, polar angles and stiffness coefficient of elastic foundation on natural frequencies of FG porous spherical cap reinforced by GPLs have been reported for the first time.
Xiangqian Zhu,Wan-Suk Yoo 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.춘계 No.-
Lumped mass modeling of cable is widely used for dynamic analyzing mooring cables in ocean. Both motions of cables and loads acting on cables are expressed with respect to the element frames. Generally, Frenet frame, which is suitable for continuous and differentiable space curves, is widely used for the lumped mass modeling in former researches. The rotational transformation matrix is based on Euler angles of which the rotation angles are carried out by inverse kinematics. However, singularities exist in the combination of the Frenet frame and Euler angles. This paper puts forward a new element frame which is created based on vectors of element orientation and relative velocity. Comparisons with the results by the Frenet frame show this new element frame is stable and overcomes singularities well.
Dynamic Analysis of a Cable Considering the Impact of Seabed
Xiangqian Zhu,Min Hyung Cho,Wan Suk Yoo 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
The lumped-mass modelling is adopted in this paper for the dynamic analysis of a mooring cable. Since the condition of the seabed affects the motion of cable, the impact of seabed is divided into vertical and horizontal components in this paper. The seabed is simplified as plane and treated as spring modelling in vertical direction; meanwhile, the friction is applied on the cable resting on seabed in horizontal direction. Considering the environments, this paper also includes the tension and damping of cable, the hydrodynamic drag forces and the effect of added-mass during building the formulation of cable modelling. Finally, this numerical modelling is verified with commercial simulation code ProteusDS.
Damage and fracture processes of concrete using acoustic emission parameters
Fan Xiangqian,Hu Shaowei,Lu Jun 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.18 No.2
In order to observe the internal damage of concrete in real time, we introduced acoustic emission nondestructive detecting technology into a series of fracture tests; the test results revealed the whole process that concrete undergoes when it sustains damage that leads to failure, according to the change rules of the acoustic emission parameters. The results showed that both the initiation and unstable loads can be accurately determined using the abrupt change of the acoustic emission rate curves and the turning point of the acoustic emission parameters’ accumulative curves. The whole process, from damage to failure, includes five phases, beginning with damage, such as cracking, a stable crack growth process, a critical unstable stage, and unstable propagation. The brittle fracture characteristics of concrete change when steel bars are joined, because the steel bars and the concrete structure bond, which causes an increase in the acoustic emission signals within the fracture process of the reinforced concrete. The unstable propagation stage is also extended. Our research results provide a valid methodology and technical explanations, which can help researchers to monitor the cracking process of concrete structures, in real time, during actual projects.