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Electrodeposition of chitosan/graphene oxide conduit to enhance peripheral nerve regeneration

Neural Regeneration Research 2023年第1期18卷 207-212页

作者： Ya-Nan Zhao Ping Wu Zi-Yuan Zhao fei-xiang chen Ao Xiao Zhi-Yi Yue Xin-Wei Han Yong Zheng Yun chen Department of Biomedical Engineering and Hubei Province Key Laboratory of Allergy and Immune Related Disease School of Basic Medical SciencesWuhan UniversityWuhanHubei ProvinceChina Department of Interventional Radiology The First Affiliated Hospital of Zhengzhou UniversityZhengzhouHenan ProvinceChina Clinical Medical College Hubei University of Science and TechnologyXianningHubei ProvinceChina

Currently available commercial nerve guidance conduits have been applied in the repair of peripheral nerve defects.However,a conduit exhibiting good biocompatibility remains to be developed.In this work,a series of chitosan/graphene oxide(GO)films with concentrations of GO varying from 0-1 wt%(collectively referred to as CHGF-n)were prepared by an electrodeposition technique.The effects of CHGF-n on proliferation and adhesion abilities of Schwann cells were evaluated.The results showed that Schwann cells exhibited elongated spindle shapes and upregulated expression of nerve regeneration-related factors such as Krox20(a key myelination factor),Zeb2(essential for Schwann cell differentiation,myelination,and nerve repair),and transforming growth factorβ(a cytokine with regenerative functions).In addition,a nerve guidance conduit with a GO content of 0.25%(CHGFC-0.25)was implanted to repair a 10-mm sciatic nerve defect in rats.The results indicated improvements in sciatic functional index,electrophysiology,and sciatic nerve and gastrocnemius muscle histology compared with the CHGFC-0 group,and similar outcomes to the autograft group.In conclusion,we provide a candidate method for the repair of peripheral nerve defects using free-standing chitosan/GO nerve conduits produced by electrodeposition.

关键词： chitosan electrodeposition free-standing graphene oxide nerve conduit nerve factors Schwann cells tissue engineerin

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Role of clinical data and multidetector computed tomography findings in acute superior mesenteric artery embolism

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World Journal of Clinical Cases 2022年第13期10卷 4020-4032页

作者： Ju-Shun Yang Zhen-Yu Xu fei-xiang chen Mei-Rong Wang Ruo-chen Cong Xiao-Le Fan Bo-Sheng He Wei Xing Department of Radiology The Third Affiliated Hospital of Soochow UniversityChangzhou 213003Jiangsu ProvinceChina Department of Radiology The Second Affiliated Hospital of Nantong UniversityNantong 226001Jiangsu ProvinceChina Department of Ultrasonography The Second People's Hospital of NantongNantong 226002Jiangsu ProvinceChina

BACKGROUND Superior mesenteric artery embolism(SMAE)has acute onset and fast progression,which seriously threatens the life of patients.Multidetector computed tomography(MDCT)is one of the most important diagnostic methods for SMAE,which plays an important role in the diagnosis and prognosis of SMAE.AIM To evaluate the value of combined clinical data and MDCT findings in the diagnosis of acute SMAE and predict the risk factors for SMAE-related death.METHODS Data from 53 SMAE patients who received abdominal MDCT multi-phase enhancement and superior mesenteric artery digital subtraction angiography examinations were collected.Univariate cox regression and multivariate cox model were used to analyze the correlation between death risk and clinical and computed tomography features in SMAE patients.RESULTS Univariate Cox regression model showed that intestinal wall thinning,intestinal wall pneumatosis,blood lactate>2.1 mmol/L and blood pH2.1 mmol/L(HR=5.26,95%CI:1.04-26.69,P=0.045)and intestinal wall thinning(HR=9.40,95%CI:1.05-83.46,P=0.044)were significantly increases the risk of death in patients with SMAE.CONCLUSION For patients with SAME,increased blood lactate and intestinal wall thinning are the risk factors for death;hence,close monitoring may reduce the mortality rate.Clinical observation combined with MDCT signs can significantly improve SMAE diagnosis.

关键词： Multidetector computed tomography Superior mesenteric artery Embolization Blood lactate

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Reduction of unactivated alkyl chlorides enabled by light-induced single electron transfer

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Science China Chemistry 2024年第2期67卷 471-481页

作者： Lei Dai Zhao-fei Zhang xiang-Yu chen School of Chemical Sciences University of the Chinese Academy of SciencesBeijing100049China Institute of Chemistry Chinese Academy of SciencesBeijing100190China Binzhou Institute of Technology Weiqiao-UCAS Science and Technology ParkBinzhou256606China

Alkyl chlorides are abundant and easily accessible starting materials.However,due to the high reduction potentials associated with unactivated alkyl chlorides,achieving their single electron reduction remains a persistent challenge.This challenge has spurred the exploration of efficient activation methods to overcome this issue.In recent years,photocatalysis has emerged as a mild and potent tool for the single electron reduction of unactivated alkyl chlorides,opening up new possibilities in this field.Considering the rapid advancements in this area,a comprehensive review that provides a conceptual understanding of this emerging field,with a specific focus on reaction design and catalytic mechanisms,would be timely and highly valuable.Hence,we present an overview of various synthetic techniques for photoinduced single electron reduction of unactivated alkyl chlorides.Furthermore,we also discuss the limitations of the present methods and future directions that lie ahead in this field.

关键词： photocatalysis unactivated alkyl chlorides single electron transfer radical reactions

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Practical cloud storage auditing using serverless computing

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Science China(Information Sciences) 2024年第3期67卷 33-47页

作者： fei chen Jianquan CAI Tao xiang Xiaofeng LIAO College of Computer Science and Software Engineering Shenzhen University College of Computer Science Chongqing University

Cloud storage auditing research is dedicated to solving the data integrity problem of outsourced storage on the cloud. In recent years, researchers have proposed various cloud storage auditing schemes using different techniques. While these studies are elegant in theory, they assume an ideal cloud storage model;that is, they assume that the cloud provides the storage and compute interfaces as required by the proposed schemes. However, this does not hold for mainstream cloud storage systems because these systems only provide read and write interfaces but not the compute interface. To bridge this gap, this work proposes a serverless computing-based cloud storage auditing system for existing mainstream cloud object storage. The proposed system leverages existing cloud storage auditing schemes as a basic building block and makes two adaptations. One is that we use the read interface of cloud object storage to support block data requests in a traditional cloud storage auditing scheme. Another is that we employ the serverless computing paradigm to support block data computation as traditionally required. Leveraging the characteristics of serverless computing, the proposed system realizes economical, pay-as-you-go cloud storage auditing. The proposed system also supports mainstream cloud storage upper layer applications(e.g., file preview) by not modifying the data formats when embedding authentication tags for later auditing. We prototyped and open-sourced the proposed system to a mainstream cloud service, i.e., Tencent Cloud. Experimental results show that the proposed system is efficient and promising for practical use. For 40 GB of data, auditing takes approximately 98 s using serverless computation. The economic cost is 120.48 CNY per year, of which serverless computing only accounts for 46%. In contrast, no existing studies reported cloud storage auditing results for real-world cloud services.

关键词： cloud storage auditing serverless computing object storage usability

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High-temperature Thermo-oxidative Aging of Vulcanized Natural Rubber Nanocomposites:Evolution of Microstructure and Mechanical Properties

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Chinese Journal of Polymer Science 2023年第8期41卷 1287-1297,I0010页

作者： Zhou-Xian Li Yi-Ran Kong xiang-fei chen Ya-Jiang Huang Ya-Dong Lv Guang-Xian Li College of polymer science and engineering State key laboratory of polymer materials engineering of ChinaSichuan UniversityChengdu 610065China

The aging of natural rubber(NR)at high temperatures will seriously affect its service lifetime in many key applications.In the present work,the changes in microstructure and mechanical properties of semi-efficient vulcanized NR/carbon black(CB)vulcanizates during thermooxidative aging at high temperatures(150-200℃)and a moderate temperature(95℃)were compared.At high temperatures,a two-stage aging behavior,which was characteristic of a first rapid decline and then a continuous rise in the crosslinking density(ve),was identified and was found to be closely related to the depletion behavior of antioxidants.The surface cracking behavior observed in the second stage of high-temperature aging was discussed in terms of the grafting reaction of macromolecular radicals on CB particles and thermal expansion.In contrast,the aging of NR at moderate temperatures was much mild,which featured a continuous increase in ve and an oxidation mechanism dominated by peroxy radicals attacking double bonds.In general,the mechanical properties of NR vulcanizates during high-temperature aging depended on the competition effects of structural evolution in the crosslinked network and oxidation-induced chain scission.

关键词： Natural rubber nanocomposites High-temperature Thermo-oxidative aging

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Laser Driver for Optic Fiber Gyro with 4 mA to 200 mA Drive Current

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Journal of Electronic Science and Technology 2013年第3期11卷 277-280页

作者： fei-xiang chen Zong-Min Wang Ying Kong Xin-Mang Peng he Beijing Microelectronics Technology Institute

Abstract---The stability of the drive current is very important for a laser driver, while it is difficult to maintain the current stable at a high value for the laser driver. On the other hand, the range of the drive current is expected to be as wide as possible to be applied to different kinds of lasers. In this paper, a high current laser driver for the superluminescent light emitting diode （SLED） is presented, which is used in the optic fiber gyro embedded by a 0.35 μm bipolar complementary metal-oxide-semiconductor transistor （BiCMOS） process. The laser driver provides automatic power control and certain value of current determined by the external resister. The system is based on the optic-electric feedback theory and uses the closed-loop control technique to maintain the drive current stable. The system is capable of producing stable current ranges from 4 mA to 200 mA when the value of external resister changes.

关键词： Index Terms---Average power control calibratedreference current high current output laser driver.

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Effect of rare earth on primary carbides in H13 die steel and their addition method:a review

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Journal of Iron and Steel Research(International) 2024年第3期31卷 531-551页

作者： Jing-feng Wang Lin-zhu Wang Chao-yi chen xiang Wang fei Zhao School of Materials and Metallurgy Guizhou UniversityGuiyang 550025GuizhouChina Zhengzhou Railway Vocational and Technical College Zhengzhou 450000HenanChina Guizhou Provincial University Key Laboratory of High Performance Battery Materials Guizhou UniversityGuiyang 550025GuizhouChina Shougang Guiyang Special Steel Co. Guiyang 550005GuizhouChina

Larger-sized primary carbides lead to stress concentration during the application of H13 hot-work die steel,resulting in microcracks and fatigue failure.Rare earth was usually added to modify the carbides and inclusions.The existing literature is reviewed on the effect of rare earth on primary carbides in H13 steel.A comprehensive review on the effect of rare earth on the characteristics of primary carbides,i.e.,number,size,morphology,and thermal stability in H13 steel,was done.The precipitation mechanism and nucleation of primary carbides with rare earth were summarized.The position and form of rare earth in steel and their effects on alloying elements segregation were reviewed.The addition techniques of rare earth in H13 steel were compared,and the prospects for other uncommon rare earth and emerging technology were present.Based on the current references,it can be known that adding rare earth facilitated refined and dispersed primary carbides.The size of primary carbides would be reduced,and their morphology would be improved because the rare earth inclusions formed in H13 steel can act as nucleation cores forγ-Fe orδ-Fe,refining the dendritic structure.Besides,the number of primary carbides at grain boundaries would be significantly reduced.However,rare earth had little impact on thermal stability.The nucleation of primary carbides tended to be inhibited due to the modification of inclusions by rare earth which were likely to be nucleation cores for primary carbides.Rare earth had been reported to affect the mechanism and process of primary carbide precipitation.Additionally,the addition of rare earth can inhibit the segregation of alloying elements and carbon diffusion by calculation.Thus,laboratory experiments and theoretical calcu-lations need to be conducted to study the states and evolution of rare earth steels.

关键词： Rare earth H13 die steel Primary carbide Nucleation Dendritic structure

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Spark plasma sintering of tungsten-based WTaVCr refractory high entropy alloys for nuclear fusion applications

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 146-154页

作者： Yongchul Yoo xiang Zhang fei Wang Xin chen Xing-Zhong Li Michael Nastasi Bai Cui Department of Mechanical&Materials Engineering University of Nebraska-LincolnLincolnNE 68588USA Nebraska Center for Materials and Nanoscience University of Nebraska-LincolnLincolnNE 68588USA Department of Nuclear Engineering Texas A&M UniversityCollege StationTX 77843USA

W-based WTaVCr refractory high entropy alloys (RHEA) may be novel and promising candidate materials for plasma facing components in the first wall and diverter in fusion reactors. This alloy has been developed by a powder metallurgy process combining mechanical alloying and spark plasma sintering (SPS). The SPSed samples contained two phases, in which the matrix is RHEA with a body-centered cubic structure, while the oxide phase was most likely Ta2VO6through a combined analysis of X-ray diffraction (XRD),energy-dispersive spectroscopy (EDS), and selected area electron diffraction (SAED). The higher oxygen affinity of Ta and V may explain the preferential formation of their oxide phases based on thermodynamic calculations. Electron backscatter diffraction (EBSD) revealed an average grain size of 6.2μm. WTaVCr RHEA showed a peak compressive strength of 2997 MPa at room temperature and much higher micro-and nano-hardness than W and other W-based RHEAs in the literature. Their high Rockwell hardness can be retained to at least 1000°C.

关键词： refractory high entropy alloy plasma-facing material fusion reactor spark plasma sintering

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Constructing electron-blocking grain boundaries in garnet to suppress lithium dendrite growth

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Journal of Advanced Ceramics 2024年第2期13卷 166-175页

作者： Xing xiang Zecheng Fang Congkun Du Zhenzhen Zhao Jiajia chen Yanhua Zhang Huihu Wang chenhuinan Wei fei chen Qiang Shen Hubei Provincial Key Laboratory of Green Materials for Light Industry Hubei University of TechnologyWuhan 430068China Hubei Longzhong Laboratory Wuhan University of Technology Xiangyang Demonstration ZoneXiangyang 441000China Collaborative Innovation Center of Green Light-weight Materials and Processing Hubei University of TechnologyWuhan 430068China New Materials and Green Manufacturing Talent Introduction and Innovation Demonstration Base Hubei University of TechnologyWuhan 430068China State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

Li_(7)La_(3)Zr_(2)O_(12)(LLZO)is considered as a promising solid-state electrolyte due to its high ionic conductivity,wide electrochemical window,and excellent electrochemical stability.However,its application in solid-state lithium metal batteries(SSLMBs)is impeded by the growth of lithium dendrites in LLZO due to some reasons such as its high electronic conductivity.In this study,lithium fluoride(LiF)was introduced into Ta-doped LLZO(LLZTO)to modify its grain boundaries to enhance the performance of SSLMBs.A nanoscale LiF layer was uniformly coated on the LLZTO grains,creating a threedimensional continuous electron-blocking network at the grain boundaries.Benefiting from the electronic insulator LiF and the special structure of the modified LLZTO,the symmetric cells based on LLZO achieved a high critical current density(CCD)of 1.1 mA·cm^(-2)(in capacity-constant mode)and maintained stability over 2000 h at 0.3 mA·cm^(-2).Moreover,the full cells combined with a LiFePO_(4)(LFP)cathode,demonstrated excellent cycling performance,retaining 97.1% of capacity retention after 500 cycles at 0.5 C.Therefore,this work provides a facile and effective approach for preparing a modified electrolyte suitable for high-performance SSLMBs.

关键词： solid electrolyte garnet lithium dendrite microstructure solid-state batteries

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Reduced macular thickness and vascular density in abnormal glucose metabolism patients: A meta-analysis of optical coherence tomography (OCT) and OCT angiography studies

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中华医学杂志(英文版) 2024年第9期137卷 1054-1068页

作者： Fu xiangyu Ren xiang chen Wenyue chen Danian Department of Ophthalmology West China Hospital Sichuan University Chengdu Sichuan China Research Laboratory of Ophthalmology and Vision Sciences State Key Laboratory of Biotherapy West China Hospital Sichuan University Chengdu Sichuan China Department of Ophthalmology The People’s Hospital of Guizhou Province Guiyang Guizhou China

Background: Alterations in macular thickness and vascular density before clinically visible diabetic retinopathy (DR) remain inconclusive. This study aimed to determine whether retinal manifestations in abnormal glucose metabolism (AGM) patients differ from those in the healthy individuals.Methods: PubMed, Embase, and Web of Science were searched between 2000 and 2021. The eligibility criteria were AGM patients without DR. Primary and secondary outcomes measured by optical coherence tomography (OCT) and OCT angiography (OCTA) were analyzed and expressed as standardized mean differences (SMDs) with 95% confidence intervals (CIs). A random-effects model was used in the data synthesis. The potential publication bias for the variables was evaluated using Egger’s test.Results: A total of 86 observational studies involving 13,773 participants and 15,416 eyes were included. OCT revealed that compared to healthy controls, the total macular thickness of AGM patients was thinner, including the thickness of fovea (–0.24, 95% CI [–0.39, –0.08];P = 0.002,I2 = 87.7%), all regions of parafovea (–0.32, 95% CI [–0.54, –0.11];P = 0.003;I2 = 71.7%) and the four quadrants of perifovea; the thickness of peripapillary retinal nerve fiber layer (pRNFL), macular retinal nerve fiber layer (mRNFL), and ganglion cell layer (GCL) also decreased. OCTA indicated that the superficial and deep vascular density decreased, the foveal avascular zone (FAZ) area enlarged, and the acircularity index (AI) reduced in AGM individuals.Conclusions: Retinal thinning and microvascular lesions have occurred before the advent of clinically detectable DR; OCT and OCTA may have the potential to detect these preclinical changes.Registration: PROSPERO; http://www.***.york.***.uk/prospero/; No. CRD42021269885.

关键词： Abnormal glucose metabolism Optical coherence tomography Optical coherence tomography angiography Diabetic retinopathy Prediabetes Meta-analysis

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