High Temperature Oxidation Resistance of NiCoCrAl High Entropy Alloy Coating on the TiAl Alloy

Yuanyuan Sun,Qiang Miao,Wenping Liang,Kai Zang,Yuting Wu,Haiyang Yu,Mengjuan Yin,Xiguang Gao,Yindong Song 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.1

The high entropy alloy coating is considered as one of the most promising methods to improve the high-temperature oxidationresistance of titanium aluminum alloys due to its fine mechanical property and thermal stability. However, the high entropyalloy coating prepared so far has poor coating quality, and low coating forming efficiency and there are certain requirementsfor the substrate alloys. To this end, a NiCoCrAl high entropy alloy coating was developed using the double glow plasmaalloying technique on the TiAl alloy. The morphology, phase structure, and high temperature oxidation resistance of thecoating were comprehensively studied. The results indicate that a uniform and dense coating with a single solid solution offace-centered cube phase formed on the alloy surface. Furthermore, isothermal oxidation test was performed, and the oxidationfailure process of the TiAl substrate and the NiCoCrAl-coated sample with different oxidation times was analyzed. It isfound that the coating efficiently prevented the TiAl alloy from degeneration for up to 100 h at 900 °C.

Optimum synthesis of esomeprazole catalyzed by Rhodococcus rhodochrous ATCC 4276 through response surface methodology

Yuanyuan Zhang,Qiuxiang Zhao,Hui Tang,Huiling Li,Depeng Li,Zhiyong Wang,Xin Gao,Fanye Wang 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.5

Enantiopure esomeprazole is an important drug in the treatment of gastric ulcer. The asymmetric sulfoxidation of omeprazole thioether was catalyzed by immobilized cells of a mutant of Rhodococcus rhodocrous ATCC 4276 to synthesize esomeprazole. The bioreaction was carried out in a biphasic system (chloroform-water), at a high substrate concentration (200mM), and optimized using response surface methodology (RSM). The optimal yield of esomeprazole obtained was 94.8% with e.e. (>99%) without the formation of the sulfone form as a byproduct, under the optimal conditions: the concentration of immobilized cells, 283.5 g/L, the incubation temperature, 37.05 oC, and pH of phosphate buffer, 7.35, respectively. A quadratic polynomial model was developed with R2 of 0.9998, which indicates that the model predicts the observed data with very high accuracy. The mutant exhibited a high enantioselective activity and substrate and product tolerance. The small size of immobilized cell beads (0.5-1 mm) creates a large reaction interface. The aerated flask provides enough oxygen for a high concentration of cells. The significant improvement of substrate tolerance may mainly be attributed to employing the chloroform-water biphasic system because organic substrates may be partitioned in the organic phase, eliminating potential damage and inhibition to cells. Based on the above, the asymmetric sulfoxidation catalyzed by immobilized bacterial cells is therefore more promising for efficient synthesis of chiral sulfoxides.

State of Charge Estimation for Li-Ion Batteries Based on an Unscented H-Infi nity Filter

Yuanyuan Liu,Tiantian Cai,Jingbiao Liu,Mingyu Gao,Zhiwei He 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.6

The state of charge (SOC) of lithium-ion batteries refl ects their remaining capacity. Accurate estimation of SOC helps battery safety and is benefi cial to the effi cient management of batteries. The charging and discharging processes of lithium-Ion batteries are very complicated, and it is diffi cult to obtain accurate SOC estimation results. Therefore, it is important to study improved algorithms for SOC estimation for this nonlinear non-Gaussian battery system. In this paper, we propose an unscented H-infi nity fi lter (UHF) based SOC estimation method, which combines the advantages of both the unscented Kalman fi lter (UKF) and the H-infi nity fi lter (HF). The UKF propagates the sigma points through the nonlinear system and does not need the fi rst-order linear approximation of the system equation, while the HF can suppress the non-Gaussian noise in the system to the greatest extent. The proposed UHF based SOC estimation algorithm is verifi ed and evaluated in the battery management system, and further optimized in practical problems. Experimental results show that the proposed UHF based algorithm can perform accurate SOC estimation for lithium-ion batteries, and is superior to the UKF based SOC estimation.

Oxymatrine inhibits the pyroptosis in rat insulinoma cells by affecting nuclear factor kappa B and nuclear factor (erythroid-derived 2)-like 2 protein/heme oxygenase-1 pathways

Jingying Gao,Lixia Xia,Yuanyuan Wei 대한약리학회 2022 The Korean Journal of Physiology & Pharmacology Vol.26 No.3

As the mechanism underlying glucose metabolism regulation by oxymatrine is unclear, this study investigated the effects of oxymatrine on pyroptosis in INS-1 cells. Flow cytometry was employed to examine cell pyroptosis and reactive oxygen species (ROS) production. Cell pyroptosis was also investigated via transmission electron microscopy and lactate dehydrogenase (LDH) release. Protein levels were detected using western blotting and interleukin (IL)-1β and IL-18 secretion by enzyme-linked immunosorbent assay. The caspase-1 activity and DNA-binding activity of nuclear factor kappa B (NF-κB) and nuclear factor (erythroid-derived 2)-like 2 protein (Nrf2) were also assessed. In the high glucose and high fat-treated INS-1 cells (HG + PA), the caspase-1 activity and LDH content, as well as Nod-like receptor family pyrin domain containing 3, Gsdmd-N, caspase-1, apoptosis-associated specklike protein containing a CARD, IL-1β, and IL-18 levels were increased. Moreover, P65 protein levels increased in the nucleus but decreased in the cytoplasm. Oxymatrine attenuated these effects and suppressed high glucose and high fat-induced ROS production. The increased levels of nuclear Nrf2 and heme oxygenase-1 (HO-1) in the HG + PA cells were further elevated after oxymatrine treatment, whereas cytoplasmic Nrf2 and Keleh-like ECH-associated protein levels decreased. Additionally, the elevated transcriptional activity of p65 in HG + PA cells was reduced by oxymatrine, whereas that of Nrf2 increased. The results indicate that the inhibition of pyroptosis in INS- 1 cells by oxymatrine, a key factor in its glucose metabolism regulation, involves the suppression of the NF-κB pathway and activation of the Nrf2/HO-1 pathway.

Polydopamine Used as Hollow Capsule and Core-Shell Structures for Multiple Applications

Xinyu Cui,Yuanyuan Yin,Zuo Ma,Yongkui Yin,Yue Guan,Shengzhong Rong,Jinxia Gao,Yingying Niu,Miaojing Li 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.5

Polydopamine (PDA) capsule and core – shell structures with tailored structures and properties are of particular interests due to their multifunctions and potential applications as new colloidal structures in diverse fields. Among the available fabrication methods, PDA film onto colloidal particles followed by selective template removal has attracted extensive attention due to its advantages of precise control over the size, wall thickness and functions of the obtained capsules. The past several years has witnessed a rapid increase of research concerning the new fabrication strategies, functionalization and applications of this kind of capsules and core – shell structures, particularly in many fields such as drug delivery, catalysis, antibacterial, etc. In this review, the very recent progress of the capsule and core – shell structures based on PDA are summarized. There are basically two sections, including the fabrication process of PDA capsules, core – shell structures, and the various applications based on PDA.

Theoretical analysis of overlay resisting crack propagation in old cement concrete pavement

Pan, Baofeng,Gao, Yuanyuan,Zhong, Yang Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.4

The main purpose of this study is to determine the effect of overlay on the crack propagation. In order to simplify the problem, a cement concrete pavement is modeled as an elastic plate on Winkler foundation. To derive the singular integral equations, the Fourier transform and dislocation density function are used. Lobatto-Chebyshev integration formula, as a numerical method, is used to solve the singular integral equations. The numerical solution of stress intensity factor at the crack tip is derived. In order to examine the effect of overlay for resisting crack propagation, numerical analyses are carried out for a cement concrete pavement with an embedded crack and a concrete pavement with an asphalt overlay. Results show the significant factors that influence the crack propagation.

Theoretical analysis of overlay resisting crack propagation in old cement concrete pavement

Baofeng Pan,Yuanyuan Gao,Yang Zhong 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.4

The main purpose of this study is to determine the effect of overlay on the crack propagation. In order to simplify the problem, a cement concrete pavement is modeled as an elastic plate on Winkler foundation. To derive the singular integral equations, the Fourier transform and dislocation density function are used. Lobatto-Chebyshev integration formula, as a numerical method, is used to solve the singular integral equations. The numerical solution of stress intensity factor at the crack tip is derived. In order to examine the effect of overlay for resisting crack propagation, numerical analyses are carried out for a cement concrete pavement with an embedded crack and a concrete pavement with an asphalt overlay. Results show the significant factors that influence the crack propagation.

Diversity-Multiplexing Tradeoff Analysis of Wireless Multiple-Antenna Cooperative Systems in General Fading Channels

( Kun Xu ),( Yuanyuan Gao ),( Xiaoxin Yi ),( Yajun Zhang ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.11

In this paper, diversity-multiplexing tradeoff (DMT) of three-user wireless multiple-antenna cooperative systems is investigated in general fading channels when half-duplex and decode-and-forward relay is employed. Three protocols, i.e., adaptive protocol, receive diversity protocol, and dual-hop relaying protocol, are considered. The general fading channels may include transmit and/or receive correlation and nonzero channel means, and are extensions of independent and identically distributed Rayleigh or Rician fading channels. Firstly, simple DMT expressions are derived for general fading channels with zero channel means and no correlation when users employ arbitrary number of antennas. Explicit DMT expressions are also obtained when all users employ the same number of antennas and the channels between any two users are of the same fading statistics. Finally, the impact of nonzero channel means and/or correlation on DMT is evaluated. It is revealed theoretically that the DMTs depend on the number of antennas at each user, channel means (except for Rayleigh and Rician fading statistics), transmit and/or receive correlation, and the polynomial behavior near zero of the channel gain probability density function. Examples are also provided to illustrate the analysis and results.

Robust Secure Transmit Design with Artificial Noise in the Presence of Multiple Eavesdroppers

( Xiaochen Liu ),( Yuanyuan Gao ),( Nan Sha ),( Guozhen Zang ),( Shijie. Wang ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.6

This paper studies secure wireless transmission from a multi-antenna transmitter to a single-antenna intended receiver overheard by multiple eavesdroppers with considering the imperfect channel state information (CSI) of wiretap channel. To enhance security of communication link, the artificial noise (AN) is generated at transmitter. We first design the robust joint optimal beamforming of secret signal and AN to minimize transmit power with constraints of security quality of service (QoS), i.e., minimum allowable signal-to-interference-and-noise ratio (SINR) at receiver and maximum tolerable SINR at eavesdroppers. The formulated design problem is shown to be nonconvex and we transfer it into linear matrix inequalities (LMIs). The semidefinite relaxation (SDR) technique is used and the approximated method is proved to solve the original problem exactly. To verify the robustness and tightness of proposed beamforming, we also provide a method to calculate the worst-case SINR at eavesdroppers for a designed transmit scheme using semidefinite programming (SDP). Additionally, the secrecy rate maximization is explored for fixed total transmit power. To tackle the nonconvexity of original formulation, we develop an iterative approach employing sequential parametric convex approximation (SPCA). The simulation results illustrate that the proposed robust transmit schemes can effectively improve the transmit performance.

Ginsenosides Rc, as a novel SIRT6 activator, protects mice against high fat diet induced NAFLD

Zehong Yang,Yuanyuan Yu,Nannan Sun,Limian Zhou,Dong Zhang,HaiXin Chen,Wei Miao,Weihang Gao,Canyang Zhang,Changhui Liu,Xiaoying Yang,Xiaojie Wu,Yong Gao The Korean Society of Ginseng 2023 Journal of Ginseng Research Vol.47 No.3

Background: Hepatic lipid disorder impaired mitochondrial homeostasis and intracellular redox balance, triggering development of non-alcohol fatty liver disease (NAFLD), while effective therapeutic approach remains inadequate. Ginsenosides Rc has been reported to maintain glucose balance in adipose tissue, while its role in regulating lipid metabolism remain vacant. Thus, we investigated the function and mechanism of ginsenosides Rc in defending high fat diet (HFD)-induced NAFLD. Methods: Mice primary hepatocytes (MPHs) challenged with oleic acid & palmitic acid were used to test the effects of ginsenosides Rc on intracellular lipid metabolism. RNAseq and molecular docking study were performed to explore potential targets of ginsenosides Rc in defending lipid deposition. Wild type and liver specific sirtuin 6 (SIRT6, 50721) deficient mice on HFD for 12 weeks were subjected to different dose of ginsenosides Rc to determine the function and detailed mechanism in vivo. Results: We identified ginsenosides Rc as a novel SIRT6 activator via increasing its expression and deacetylase activity. Ginsenosides Rc defends OA&PA-induced lipid deposition in MPHs and protects mice against HFD-induced metabolic disorder in dosage dependent manner. Ginsenosides Rc (20mg/kg) injection improved glucose intolerance, insulin resistance, oxidative stress and inflammation response in HFD mice. Ginsenosides Rc treatment accelerates peroxisome proliferator activated receptor alpha (PPAR-α, 19013)-mediated fatty acid oxidation in vivo and in vitro. Hepatic specific SIRT6 deletion abolished ginsenoside Rc-derived protective effects against HFD-induced NAFLD. Conclusion: Ginsenosides Rc protects mice against HFD-induced hepatosteatosis by improving PPAR-α-mediated fatty acid oxidation and antioxidant capacity in a SIRT6 dependent manner, and providing a promising strategy for NAFLD.