Advances of molecular dynamics simulation in tribochemistry and lubrication investigations: A review

Jiaqi He,Huajie Tang,Chenglong Wang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.126 No.-

As a hot topic in recent years, molecular dynamics (MD) simulation has become an effective tool in tribochemistryand lubrication investigations, which provides unique insight on dealing with these issues fromatomic scale. This review paper presents an overview of recent MD simulation studies on revealing the frictionlaws, wear mechanism and lubrication performance of materials and lubricants, which aims to provideguidance and reference for future theoretical investigations on revealing the essence of friction, wear andlubrication. MD simulation researches upon the tribology, tribochemistry and lubrication are summarized,focusing on the field of friction and wear mechanism, nano-tribology, liquid lubricants, lubricant additives,superlubricity phenomenon, etc. Besides, the challenges and problems remain to be considered, as well asfuture development directions of MD simulation are briefly discussed.With the help of MD method, the obstacleto tribology research caused by insufficient experimental methods can be reduced in the future.

Calculation of thermal neutron scattering data of MgF2 and its effect on beam shaping assembly for BNCT

Hu Jiaqi,Qiao Zhaopeng,Fan Lunhe,Tang Yongqiang,Cao Liangzhi,Zu Tiejun,He Qingming,Li Zhifeng,Wang Sheng 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.4

MgF2 as a moderator material has been extensively used in the beam shaping assembly (BSA) that plays an important role in the boron neutron capture therapy (BNCT). Regarded as important for applications, the thermal neutron scattering data of MgF2 were calculated, based on the phonon expansion model. The structural properties of MgF2 were researched by the VASP code based on the ab-initio methods. The PHONOPY code was employed to calculate the phonon density of states. Furthermore, the NJOY code was used to calculate the thermal neutron scattering data of MgF2. The calculated inelastic cross sections plus absorption cross sections are in agreement with the available experimental data. The neutron transport in the BSA has been simulated by using a hybrid Monte-Carlo-Deterministic code NECP-MCX. The results indicated that compared with the calculation of the free gas model, the thermal neutron flux and epithermal neutron flux at the BSA exit port calculated by using the thermal neutron scattering data of MgF2 were reduced by 27.7% and 8.2%, respectively.

MiR-126-3p inhibits apoptosis and promotes proliferation by targeting phosphatidylinositol 3-kinase regulatory subunit 2 in porcine ovarian granulosa cells

Zhou, Xiaofeng,He, Yingting,Jiang, Yao,He, Bo,Deng, Xi,Zhang, Zhe,Yuan, Xiaolong,Li, Jiaqi Asian Australasian Association of Animal Productio 2020 Animal Bioscience Vol.33 No.6

Objective: Numerous studies have indicated that the apoptosis and proliferation of granulosa cells (GCs) are closely related to the normal growth and development of follicles and ovaries. Previous evidence has suggested that miR-126-3p might get involved in the apoptosis and proliferation of GCs, and phosphatidylinositol 3-kinase regulatory subunit 2 (PIK3R2) gene has been predicted as one target of miR-126-3p. However, the molecular regulation of miR-126-3p on PIK3R2 and the effects of PIK3R2 on porcine GCs apoptosis and proliferation remain virtually unexplored. Methods: In this study, using porcine GCs as a cellular model, luciferase report assay, mutation and deletion were applied to verify the targeting relationship between miR-126-3p and PIK3R2. Annexin-V/PI staining and 5-ethynyl-2'-deoxyuridine assay were applied to explore the effect of PIK3R2 on GCs apoptosis and proliferation, respectively. Real-time quantitative polymerase chain reaction and Western Blot were applied to explore the regulation of miR-126-3p on PIK3R2 expression. Results: We found that miR-126-3p targeted at PIK3R2 and inhibited its mRNA and protein expression. Knockdown of PIK3R2 significantly inhibited the apoptosis and promoted the proliferation of porcine GCs, and significantly down-regulated the mRNA expression of several key genes of PI3K pathway such as insulin-like growth factor 1 receptor (IGF1R), insulin receptor (INSR), pyruvate dehydrogenase kinase 1 (PDK1), and serine/threonine kinase 1 (AKT1). Conclusion: MiR-126-3p might target and inhibit the mRNA and protein expressions of PIK3R2, thereby inhibiting GC apoptosis and promoting GC proliferation by down-regulating several key genes of the PI3K pathway, IGF1R, INSR, PDK1, and AKT1. These findings would provide great insight into further exploring the molecular regulation of miR-126-3p and PIK3R2 on the functions of GCs during the folliculogenesis in female mammals.

Prevention of acetaminophen-induced hepatocyte injury: JNK inhibition and GSTA1 involvement

Chang Yicong,He Jingshan,Ma Bingke,Ishfaq Muhammad,Wang Jiaqi,Zhang Ruichen,Yuan Liang,Liu Jiarui,Li Changwen,Liu Fangping 대한독성 유전단백체 학회 2021 Molecular & cellular toxicology Vol.17 No.2

Background Glutathione S-transferase A1 (GSTA1) is a detoxification enzyme and a sensitive marker for hepatotoxicity. We investigated the effects of JNK inhibition on different degrees of Acetaminophen (APAP)-induced hepatocyte injury and GSTA1 expression. Objective This study aimed to investigate the role of JNK signaling pathway in APAP-induced different degrees of hepatocyte injury and its correlation with GSTA1 by inhibiting the phosphorylation of JNK by SP600125. Results 6 and 8 mM APAP induced different degrees of hepatocyte injury and apoptosis, both activated JNK signaling pathway. In contrast, JNK inhibitor significantly reduced activation of JNK and c-JUN on exposure to APAP. Meanwhile, the levels of hepatocyte injury, oxidative stress, and apoptosis obviously decreased. Importantly, GSTA1 expression was significantly increased by JNK inhibition. Conclusions JNK inhibition attenuates APAP-induced hepatocyte injury and oxidative stress and increases GSTA1 expression. Furthermore, GSTA1 may be involved in this signaling pathway for detoxification. Background Glutathione S-transferase A1 (GSTA1) is a detoxification enzyme and a sensitive marker for hepatotoxicity. We investigated the effects of JNK inhibition on different degrees of Acetaminophen (APAP)-induced hepatocyte injury and GSTA1 expression. Objective This study aimed to investigate the role of JNK signaling pathway in APAP-induced different degrees of hepatocyte injury and its correlation with GSTA1 by inhibiting the phosphorylation of JNK by SP600125. Results 6 and 8 mM APAP induced different degrees of hepatocyte injury and apoptosis, both activated JNK signaling pathway. In contrast, JNK inhibitor significantly reduced activation of JNK and c-JUN on exposure to APAP. Meanwhile, the levels of hepatocyte injury, oxidative stress, and apoptosis obviously decreased. Importantly, GSTA1 expression was significantly increased by JNK inhibition. Conclusions JNK inhibition attenuates APAP-induced hepatocyte injury and oxidative stress and increases GSTA1 expression. Furthermore, GSTA1 may be involved in this signaling pathway for detoxification.

Efficiency optimization of variable‑frequency controlled power factor correction converters

Yufei Zhou,Xueru He,Shuai Liu,Feng Hong,Jiaqi Ren,Dongdong Li 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.6

More attention is being paid to energy effi ciency and harmonic reduction. Thus, power factor correction (PFC) is widely used in power supplies. However, under the condition of light load, the single-stage LLC PFC converter has the problems of low effi ciency and output voltage misaligned, such as other PFC topologies. Aiming at the problems that occur under light load conditions, this paper proposes a least-pulse delta (Δ)–sigma (Σ) modulation (LPΔ–Σ modulation). Under diff erent loads, the system can automatically select the appropriate pulse density and reduce the energy transfer to the secondary side by uniformly turning off the driving signals, which stabilizes the output voltage and improves the system effi ciency. Meanwhile, LPΔ–Σ modulation is more benefi cial for improving the PF value when compared with the burst mode under light load conditions. Experimental results show that LPΔ–Σ modulation based on the traditional dual-loop control can eff ectively stabilize the output voltage and improve effi ciency. When compared with the existing burst control scheme, it reduces the output voltage ripple and eff ectively improves the PF.

Research Progress of Interface Conditions and Tribological Reactions: A Review

Huajie Tang,Jianlin Sun,Jiaqi He,Ping Wu 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.94 No.-

Tribology plays a crucial role in progress of industry and engineering. The dependence of interfaceconditions and interfacial reactions provides the strategies for friction reduction as well as anti-wear inindustrial processes. That is to modify the surface structure of materials or tune the properties oflubricants. This review provides an overview on the important interface conditions and surface-inducedtribological reactions with emphasis on the underlying of their formation and action mechanism. Thetribological features of asperity, debris and surface texture arefirstly dictated. Then the main surfaceinducedphysicochemical reactions including wetting/dewetting, deposition/adsorption are discussed. Inparticular, the thermal, mechanical and electrical effects that trigger tribochemical reactions are alsoaddressed. Finally, some deficiencies in related investigations are summarized, with perspectives for thedevelopment of tribology in both science research and industrial application.

Schisantherin A Improves Learning and Memory of Mice with D-Galactose-Induced Learning and Memory Impairment Through Its Antioxidation and Regulation of p19/p53/p21/ Cyclin D1/CDK4/RB Gene Expressions

Cong Liu,Weijing Sun,Ning Li,Jiaqi Gao,Chunyan Yu,Chunmei Wang,Jinghui Sun,Shu Jing,JianGuang Chen,He Li 한국식품영양과학회 2018 Journal of medicinal food Vol.21 No.7

Schisantherin A (SCA) was evaluated for possible function in restoring the learning and memory impairment induced by D-galactose in mice. ICR mice were treated with D-galactose subcutaneously (220 mg·kg−1), and followed by SCA in different doses (1.25, 2.50 and 5.00 mg·kg−1, administered orally) for 42 days. Effects of SCA on learning and memory were examined by step-through tests and Morris water maze tests. The activity of superoxide dismutase (SOD), the content of malondialdehyde (MDA) in the peripheral blood and hippocampus of mice were assayed by water-soluble tetrazolium-1 (WST-1) and thiobarbituric acid (TBA) methods. The contents of 8 hydroxy deoxy guanosine (8-OHdG) in the hippocampus of mice were detected by immunosorbent assay methods, respectively. Quantitative real-time PCR and Western Blot were respectively used to detect the expression of p19, p53, p21, cyclin D1, CDK4 and RB genes, and the phosphorylation of RB in the hippocampus of mice. We found that SCA significantly improved the learning and memory impairment induced by D-galactose in mice. After SCA treatment, SOD activity was increased and the content of MDA was decreased in both peripheral blood and hippocampus of mice. 8-OHDG content was also decreased in the hippocampus of mice. Furthermore, the expression of p19, p53 and p21 genes was reduced and the expression of cyclin D1 and CDK4 and the phosphorylation of RB protein were elevated in the hippocampus. SCA may improve the learning and memory impairment induced by D-galactose by enhancing the antioxidant capacity, and regulating the expression of p19/p53/p21/cyclinD1/CDK4 genes, and the phosphorylation of RB protein in the hippocampus of mice.

Genome wide association study on feed conversion ratio using imputed sequence data in chickens

Jiaying Wang,Xiaolong Yuan,Shaopan Ye,Shuwen Huang,Yingting He,Hao Zhang,Jiaqi Li,Xiquan Zhang,Zhe Zhang 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.4

Objective: Feed consumption contributes a large percentage for total production costs in the poultry industry. Detecting genes associated with feeding traits will be of benefit to improve our understanding of the molecular determinants for feed efficiency. The objective of this study was to identify candidate genes associated with feed conversion ratio (FCR) via genome-wide association study (GWAS) using sequence data imputed from single nucleotide polymorphism (SNP) panel in a Chinese indigenous chicken population. Methods: A total of 435 Chinese indigenous chickens were phenotyped for FCR and were genotyped using a 600K SNP genotyping array. Twenty-four birds were selected for sequencing, and the 600K SNP panel data were imputed to whole sequence data with the 24 birds as the reference. The GWAS were performed with GEMMA software. Results: After quality control, 8,626,020 SNPs were used for sequence based GWAS, in which ten significant genomic regions were detected to be associated with FCR. Ten candidate genes, ubiquitin specific peptidase 44, leukotriene A4 hydrolase, ETS transcription factor, R-spondin 2, inhibitor of apoptosis protein 3, sosondowah ankyrin repeat domain family member D, calmodulin regulated spectrin associated protein family member 2, zinc finger and BTB domain containing 41, potassium sodium-activated channel subfamily T member 2, and member of RAS oncogene family were annotated. Several of them were within or near the reported FCR quantitative trait loci, and others were newly reported. Conclusion: Results from this study provide valuable prior information on chicken genomic breeding programs, and potentially improve our understanding of the molecular mechanism for feeding traits.

BK Channel Deficiency in Osteoblasts Reduces Bone Formation via the Wnt/β-Catenin Pathway

Jiang, Lan,Yang, Qianhong,Gao, Jianjun,Yang, Jiahong,He, Jiaqi,Xin, Hong,Zhang, Xuemei Korean Society for Molecular and Cellular Biology 2021 Molecules and cells Vol.44 No.8

Global knockout of the BK channel has been proven to affect bone formation; however, whether it directly affects osteoblast differentiation and the mechanism are elusive. In the current study, we further investigated the role of BK channels in bone development and explored whether BK channels impacted the differentiation and proliferation of osteoblasts via the canonical Wnt signaling pathway. Our findings demonstrated that knockout of Kcnma1 disrupted the osteogenesis of osteoblasts and inhibited the stabilization of β-catenin. Western blot analysis showed that the protein levels of Axin1 and USP7 increased when Kcnma1 was deficient. Together, this study confirmed that BK ablation decreased bone mass via the Wnt/β-catenin signaling pathway. Our findings also showed that USP7 might have the ability to stabilize the activity of Axin1, which would increase the degradation of β-catenin in osteoblasts.