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Mao Jianxin,Wang Di,Wang Dong,Wu Qi,Shang Qiliang,Gao Chu,Wang Huanbo,Wang Han,Du Mu,Peng Pandi,Jia Haoruo,Xu Xiaolong,Wang Jie,Yang Liu,Luo Zhuojing 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-
Mitochondrial dysfunction plays a major role in the development of intervertebral disc degeneration (IDD). Sirtuin 5 (SIRT5) participates in the maintenance of mitochondrial homeostasis through its desuccinylase activity. However, it is still unclear whether succinylation or SIRT5 is involved in the impairment of mitochondria and development of IDD induced by excessive mechanical stress. Our 4D label-free quantitative proteomic results showed decreased expression of the desuccinylase SIRT5 in rat nucleus pulposus (NP) tissues under mechanical loading. Overexpression of Sirt5 effectively alleviated, whereas knockdown of Sirt5 aggravated, the apoptosis and dysfunction of NP cells under mechanical stress, consistent with the more severe IDD phenotype of Sirt5 KO mice than wild-type mice that underwent lumbar spine instability (LSI) surgery. Moreover, immunoprecipitation-coupled mass spectrometry (IP-MS) results suggested that AIFM1 was a downstream target of SIRT5, which was verified by a Co-IP assay. We further demonstrated that reduced SIRT5 expression resulted in the increased succinylation of AIFM1, which in turn abolished the interaction between AIFM1 and CHCHD4 and thus led to the reduced electron transfer chain (ETC) complex subunits in NP cells. Reduced ETC complex subunits resulted in mitochondrial dysfunction and the subsequent occurrence of IDD under mechanical stress. Finally, we validated the efficacy of treatments targeting disrupted mitochondrial protein importation by upregulating SIRT5 expression or methylene blue (MB) administration in the compression-induced rat IDD model. In conclusion, our study provides new insights into the occurrence and development of IDD and offers promising therapeutic approaches for IDD.
Fatigue Behavior of High-Performance Steel Beams Subjected to Different Corrosion Conditions
Ying Chai,Jianxin Peng,Linfa Xiao,Xinhua Liu,Jianren Zhang 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.4
The existing research mainly considers the fatigue properties of steel structures under the influence of the environment, corrosion rate, and load conditions without considering the effect of corrosion locations and areas. However, corrosion can happen to a steel structure in a practical engineering setting at any position. This paper investigates the fatigue behavior of high-performance steel beams (Q550E) subjected to different corrosion conditions through various tests. Results show that the fatigue life of the wholly corroded steel beams decreases as the frequency increases and increases as the stress ratio increases. Additionally, local corrosion has a greater impact on flexural stiffness than whole corrosion, and the lower half area has a greater impact than the right half area. Other corroded steel beams, with the exception of SCU-10, have fracture positions that are within the corrosion area. Because, despite the corrosion in the bending shear section, the fatigue strength of the corrosion area is higher than that of the fracture location. In addition, the degradation curves of the mid-span flexural stiffness of other steel beams under cyclic loading have not observed S-shaped curve characteristics, with the exception of GC-10B and SCU-20.
Huang Tang,Jianxin Peng,C.S. Cai,Deuckhang D. K. Lee 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.5
The main goal of this study is to investigate the eff ect of local corrosion at the mid-span region on the fl exural behavior of HPS (high-performance steel) beams. Four Q550E HPS beams were designed and subjected to electrochemically accelerated corrosion. The 3D scanning technology was used to analyze the geometric characteristics of corrosion regions. After the fourpoint fl exural test, the relationship between the degradation of fl exural behavior and the corrosion ratio or corroded location (right side of pure bending section and lower half of pure bending section) was studied in details. The FE (fi nite element) model of corroded HPS beams was established and strictly verifi ed by comparing with the tested results. Additionally, different heights and thicknesses of the corroded parts were considered in the FE models. Failure modes and bearing capacity degradation of the HPS beams caused by local corrosion were studied by analyzing above parameters. The results shows that the corrosion at the compressive fl ange of bending section has a greater infl uence on the ultimate bearing capacity than tension fl ange and web. The HPS beam corroded in right side of pure bending section has the most signifi cant compressive fl ange buckling compared. The failure mode of HPS beams with corrosion in lower half of pure bending section changes from obviously compressive fl ange buckling and local web yielded to all web yielded with the increase of corrosion ratio. The infl uence of bottom fl ange corrosion on remaining critical buckling load of beam is slightly more signifi cant than the ultimate load, but the infl uence degree of top fl ange corrosion on above two loads are basically the same.
Lightweight and Ultrastrong Polymer Foams with Unusually Superior Flame Retardancy
Xu, Linli,Xiao, Linhong,Jia, Pan,Goossens, Karel,Liu, Peng,Li, Hui,Cheng, Chungui,Huang, Yong,Bielawski, Christopher W.,Geng, Jianxin American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.31
<P>High-performance flame-retardant materials are urgently needed to address outstanding issues that pertain to safety. Traditional flame retardants are toxic to the environment and/or lack the physical properties required for use in many contemporary applications. Here, we show that isocyanate-based polyimide (PI) foam, a flammable material, can exhibit unusually superior flame retardancy as well as, other excellent properties, such as being lightweight and displaying high mechanical strength, by incorporating red phosphorus (RP)-hybridized graphene. The covalent bonds formed between the graphene platelets and the PI matrix provide the resultant PI foam with a specific Young's modulus (83 kNm kg(-1)) that is comparable to or even higher than those displayed by state-of-the-art foams, including silica aerogels, polystyrene foams, and polyurethane foams. In addition, even a low content of the RP -hybridized graphene (2.2 wt %) results in an exceptionally higher limiting oxygen index (39.4) than those of traditional flame-retardant polymer-based materials (typically 20-30). The resultant PI foam also exhibits thermal insulation properties that are similar to that of air. Moreover, the RP -hybridized graphene is prepared using a one-step ball milling process in 100% yield, and does not require solvent or produce waste. The preparation of the flame-retardant PI foams can be scaled as the starting materials are commercially available and the techniques employed are industrially compatible.</P>