Micro Galvanic Cell To Generate PtO and Extend the Triple-Phase Boundary during Self-Assembly of Pt/C and Nafion for Catalyst Layers of PEMFC

Long, Zhi,Gao, Liqin,Li, Yankai,Kang, Baotao,Lee, Jin Yong,Ge, Junjie,Liu, Changpeng,Ma, Shuhua,Jin, Zhao,Ai, Hongqi American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.44

<P>The self-assembly powder (SAP) with varying Nafion content was synthesized and characterized by XRD, XPS, HRTEM, and mapping. It is observed that the oxygen from oxygen functional groups transfers to the surface of Pt and generate PtO during the process of self-assembly with the mechanism of micro galvanic cell, where Pt, carbon black, and Nafion act as the anode, cathode and electrolyte, respectively. The appearance of PtO on the surface of Pt leads to a turnover of Nafion structure, and therefore more hydrophilic sulfonic groups directly contact with Pt, and thus the triple-phase boundary (TPB) has been expanded.</P>

Trimethyl-Ammonium Alkaline Anion Exchange Membranes with the Vinylbenzyl Chloride/Acrylonitrile Main Chain

Zhenghan Li,Junjie Chen,JinYue Zhou,YiWen Nie,Chunhui Shen,Shanjun Gao 한국고분자학회 2021 Macromolecular Research Vol.29 No.7

The main chain of polyolefin was synthesized by copolymerization of 4 - vinylbenzyl chloride (VBC) and acrylonitrile (AN), and trimethylamine is used for quaternization to prepare heterogeneous benzyl trimethyl-ammonium anion exchange membranes (Heter-X) and homogeneous benzyl trimethyl-ammonium anion exchange membrane (Homo-X). The results of Fourier-transform infrared (FT-IR), gel permeation chromatography (GPC), and 1H nuclear magnetic resonance (NMR) showed that VBC and AN were successfully copolymerized to form a polymer with a certain molecular weight, and trimethylamine was successfully quaternized. The prepared membranes exhibited good thermal stability and mechanical properties. The theoretical ion exchange capacity (IEC) values of Homo-3 and Heter-3 are the same, but the conductivity at 80 °C were 0.0572 S cm-1 and 0.0505 S cm-1. The results showed that the homogeneous method has a higher degree of quaternization and a more uniform distribution of quaternary ammonium groups, forming a more obvious microphase separation structure, which can also be seen in the atomic force microscopy (AFM) diagram. After being soaked in 1M KOH solution for 480 h, the ionic conductivity of Homo-6 and Heter-6 can still remain 91.4% and 85.5%, and the IEC loss rates were 17.21% and 24.34%. These results indicate that the prepared membranes are promising materials for application in fuel cells.

Inter-server Computation Offloading and Resource Allocation in Multi-drone Aided Space-Air-Ground Integrated IoT Networks

Yongpeng Shi,Junjie Zhang,Ya Gao,Yujie Xia 한국통신학회 2022 Journal of communications and networks Vol.24 No.3

Combining mobile edge computing (MEC), themulti-drone aided space-air-ground integrated Internet of things(SAG-IoT) networks can provide ground IoT devices (GIDs) highqualitywireless access and computing services. However, the diversetasks, moving drones, and limited network resources revealgreat challenges for the task offloading and resource allocationscheme exploitation. Especially, given the restricted computationresources, how to make full use of available applications deployedon MEC servers (MECSs) to compute various types of tasks, iseven an important issue. To the best of our knowledge, it is anentirely new problem since most existing works in this line assumethat all types of applications can be deployed on one MECS so asto process various offloaded tasks. Toward this end, we presentthis paper to investigate inter-server computation offloading, resourceallocation, and drone deployment to minimize the overallcomputation overhead of all GIDs. An iteratively optimizationalgorithm is proposed which alternately utilizes heuristic greedyand successive convex approximation methods. Simulation resultsverify that, for different GID numbers, optimization schemes, andcomputing models, our devised schemes can not only significantlyreduce the overall computation overhead but also achieve optimaldecisions of computation offloading, spectrum allocation, anddrone deployment.

Glucocorticoid-induced expansion of classical monocytes contributes to bone loss

Liu Pei,Gao Youshui,Luo Pengbo,Yu Hongping,Guo Shang,Liu Fuyun,Gao Junjie,Xu Jianzhong,Wang Shengdian,Zhang Changqing 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Classical monocytes are commonly involved in the innate inflammatory response and are the progenitors of osteoclasts. Excess endogenous glucocorticoids (GCs) can increase the levels of classical monocytes in blood and bone marrow. The role of this cell population in high-dose exogenous GC-induced osteoporosis (GIOP) remains to be elucidated. In this study, GIOP was established in rats and mice by daily methylprednisolone injection, and monocyte subsets were analyzed by flow cytometry. We demonstrated that classical monocytes accumulate in bone marrow during GIOP. Similarly, the monocyte proportion among bone marrow nucleated cells was also increased in patients with steroid treatment history. We sorted classical monocytes and analyzed their transcriptional profile in response to GCs by RNA sequencing. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that classical monocytes isolated from GC-treated rats exhibited osteoclast differentiation potential. Deletion of classical monocytes by clodronate liposome treatment prevented GIOP via inhibition of osteoclastogenesis and restoration of CD31HiendomucinHi vessels. Regarding the molecular mechanism, classical monocytes express high levels of glucocorticoid receptors. In vitro treatment with GCs increased both the percentage and absolute number of monocytes and promoted their proliferation. In summary, classical monocytes mediated GC-induced bone loss and are a potential target for therapeutic intervention in GIOP treatment.

Transient heat transfer and crust evolution during debris bed melting process in the hypothetical severe accident of HPR1000

Lv Chao,Li Gen,Gao Jinchen,Wang Jinshi,Yan Junjie 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.8

In the late in-vessel phase of a nuclear reactor severe accident, the internal heat transfer and crust evolution during the debris bed melting process have important effects on the thermal load distribution along the vessel wall, and further affect the reactor pressure vessel (RPV) failure mode and the state of melt during leakage. This study coupled the phase change model and large eddy simulation to investigate the variations of the temperature, melt liquid fraction, crust and heat flux distributions during the debris bed melting process in the hypothetical severe accident of HPR1000. The results indicated that the heat flow towards the vessel wall and upper surface were similar at the beginning stage of debris melting, but the upward heat flow increased significantly as the development of the molten pool. The maximum heat flux towards the vessel wall reached 0.4 MW/m2 . The thickness of lower crust decreased as the debris melting. It was much thicker at the bottom region with the azimuthal angle below 20 and decreased rapidly at the azimuthal angle around 20e50. The maximum and minimum thicknesses were 2 and 90 mm, respectively. By contrast, the distribution of upper crust was uniform and reached stable state much earlier than the lower crust, with the thickness of about 10 mm. Moreover, the sensitivity analysis of initial condition indicated that as the decrease of time interval from reactor scram to debris bed driedout, the maximum debris temperature and melt fraction became larger, the lower crust thickness became thinner, but the upper crust had no significant change. The sensitivity analysis of in-vessel retention (IVR) strategies indicated that the passive and active external reactor vessel cooling (ERVC) had little effect on the internal heat transfer and crust evolution. In the case not considering the internal reactor vessel cooling (IRVC), the upper crust was not obvious

Quintic Polynomial-based Obstacle Avoidance Trajectory Planning and Tracking Control Framework for Tractor-trailer System

Ming Yue,Xiangmin Wu,Lie Guo,Junjie Gao 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.10

In this paper, a dynamic automatic obstacle avoidance trajectory planning and tracking control framework is proposed for tractor-trailer system. Tractor-trailer is a special class of multibody and nonholonomic system, whose backward and forward operations have difference kinetic mechanisms. Because the obstacle avoidance behaviors are concerned with the two motion modes, the kinematic models including backward and forward movements are firstly derived. Secondly, a time-based quintic polynomial function is developed to plan two kinds of dynamic obstacle avoidance trajectories based on dynamics constraints and the information from on board sensors, so as to minimize the collision risk. Thirdly, a model predictive control (MPC)-based posture controller is designed, by which better tracking performance can be achieved for both forward and backward obstacle avoidance maneuvers. Lastly, the simulation results validate the effectiveness of the proposed dynamic obstacle avoidance framework and the designed methods.

Identification and Expression Patterns of fvexpl1, an Expansin-Like Protein-Encoding Gene, Suggest an Auxiliary Role in the Stipe Morphogenesis of Flammulina velutipes

( Qianhui Huang ),( Xing Han ),( Irum Mukhtar ),( Lingling Gao ),( Rongmei Huang ),( Liping Fu ),( Junjie Yan ),( Yongxin Tao ),( Bingzhi Chen ),( Baogui Xie ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.4

Expansins are cell wall proteins that mediate cell wall loosening and promote specific tissue and organ morphogenesis in plants and in some microorganisms. Unlike plant expansins, the biological functions of fungal expansin-like proteins have rarely been discussed. In the present study, an expansin-like protein-encoding fvexpl1 gene, was identified from Flammulina velutipes by using local BLAST. It consisted of five exons with a total length of 822 bp. The deduced protein FVEXPL1 contained 274 amino acids with a predicted molecular mass and isoelectric point of 28,589 Da and pH 4.93, respectively. The first 19 amino acids from the N terminal are the signal peptide. Phylogenetic analysis and multiple protein alignment indicated FVEXPL1 was an expansin-like protein. The expression level of fvexpl1 gene in the stipe was significantly higher than that in the mycelia, primordia, and cap. However, the expression level of fvexpl1 gene was significantly higher in the fast elongation region of the stipe as compared with the slow elongation region. Expression analysis indicated that fvexpl1 gene might have an auxiliary role in the stipe morphogenesis of F. velutipes.

Ginsenosides Rg1 regulate lipid metabolism and temperature adaptation in Caenorhabditis elegans

Hao Shi,Jiamin Zhao,Yiwen Li,Junjie Li,Yunjia Li,Jia Zhang,Zhantu Qiu,Chaofeng Wu,Mengchen Qin,Chang Liu,Zhiyun Zeng,Chao Zhang,Lei Gao 고려인삼학회 2023 Journal of Ginseng Research Vol.47 No.4

Indirect-direct band gap transition through electric tuning in bilayer MoS2.

Zhang, Z Y,Si, M S,Wang, Y H,Gao, X P,Sung, Dongchul,Hong, Suklyun,He, Junjie American Institute of Physics 2014 The Journal of chemical physics Vol.140 No.17

<P>We investigate the electronic properties of bilayer MoS2 exposed to an external electric field by using first-principles calculations. It is found that a larger interlayer distance, referring to that by standard density functional theory (DFT) with respect to that by DFT with empirical dispersion corrections, makes indirect-direct band gap transition possible by electric control. We show that external electric field effectively manipulates the valence band contrast between the K- and γ-valleys by forming built-in electric dipole fields, which realizes an indirect-direct transition before a semiconductor-metal transition happens. Our results provide a novel efficient access to tune the electronic properties of two-dimensional layered materials.</P>

Mechanical overload-induced release of extracellular mitochondrial particles from tendon cells leads to inflammation in tendinopathy

Chen Ziming,Li Mengyuan,Chen Peilin,Tai Andrew,Li Jiayue,Bassonga Euphemie Landao,Gao Junjie,Liu Delin,Wood David,Kennedy Brendan F.,Zheng Qiujian,Zheng Ming H. 생화학분자생물학회 2024 Experimental and molecular medicine Vol.56 No.-

Tendinopathy is one of the most common musculoskeletal diseases, and mechanical overload is considered its primary cause. However, the underlying mechanism through which mechanical overload induces tendinopathy has not been determined. In this study, we identified for the first time that tendon cells can release extracellular mitochondria (ExtraMito) particles, a subtype of medium extracellular particles (mEPs), into the environment through a process regulated by mechanical loading. RNA sequencing systematically revealed that oxygen-related reactions, extracellular particles, and inflammation were present in diseased human tendons, suggesting that these factors play a role in the pathogenesis of tendinopathy. We simulated the disease condition by imposing a 9% strain overload on three-dimensional mouse tendon constructs in our cyclic uniaxial stretching bioreactor. The three-dimensional mouse tendon constructs under normal loading with 6% strain exhibited an extended mitochondrial network, as observed through live-cell confocal laser scanning microscopy. In contrast, mechanical overload led to a fragmented mitochondrial network. Our microscopic and immunoblot results demonstrated that mechanical loading induced tendon cells to release ExtraMito particles. Furthermore, we showed that mEPs released from tendon cells overloaded with a 9% strain (mEP9%) induced macrophage chemotaxis and increased the production of proinflammatory cytokines, including IL-6, CXCL1, and IL-18, from macrophages compared to mEP0%, mEP3%, and mEP6%. Partial depletion of the ExtraMito particles from mEP9% by magnetic-activated cell sorting significantly reduced macrophage chemotaxis. N-acetyl-L-cysteine treatment preserved the mitochondrial network in overloaded tendon cells, diminishing overload-induced macrophage chemotaxis toward mEP9%. These findings revealed a novel mechanism of tendinopathy; in an overloaded environment, ExtraMito particles convey mechanical response signals from tendon cells to the immune microenvironment, culminating in tendinopathy.