检索结果-南通市图书馆

Influence of Voltage on the Corrosion and Wear Resistance of MicroArc Oxidation Coating on Mg-8Li-2Ca Alloy

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2019年第2期32卷 194-204页

作者： bing-yu qian Wei Miao Min Qiu Fan Gao Dong-Hui Hu Jian-Feng Sun Rui-Zhi Wu Boris Krit Sergey Betsofen College of Material Science and Engineering Heilongjiang University of Science and Technology Key Laboratory of Superlight Materials and Surface Technology Ministry of Education Harbin Engineering University College of Science Heihe University Moscow Aviation Institute National Research University

Calcium phosphate(CaP) coatings were prepared on Mg–8Li–2Ca magnesium alloy by micro-arc oxidation(MAO) in an alkaline Na_3PO_4–Ca[C_3H_7O_6P] base solution at the different applied voltages. Scanning electron microscope and X-ray diffraction were employed to characterize the microstructure and phase composition of the coatings, respectively. The corrosion resistance of the coatings was assessed by potential dynamic polarization curves, electrochemical impedance spectroscopy and hydrogen evolution experiment in simulated body fluids solution. The friction and wear properties were evaluated by friction and wear testing machine. The results demonstrate that the coating surface is porous and mainly composed of MgO, Ca_5(PO_4)_3(OH) and CaH_2P_2O_5. With the increase in voltage, the corrosion resistance and wear resistance of the MAO coating are both enhanced. The corrosion current density of the MAO coating decreases about two orders of the magnitude compared to the substrate. Additionally, wear and corrosion mechanisms are discussed.

关键词： Magnesium alloy Micro-arc oxidation Electrochemical impedance Wear mechanisms

Evolutions of Microstructure and Mechanical Properties in Mg-5Li-1Zn-0.5Ag-0.5Zr-xGd Alloy

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2023年第2期36卷 215-228页

作者： bing-yu qian Rui-Zhi Wu Jian-Feng Sun Jing-Huai Zhang Le-Gan Hou Xiao-Chun Ma Jia-Hao Wang Hai-Ting Hu Key Laboratory of Superlight Materials&Surface Technology Ministry of EducationHarbin Engineering UniversityHarbin150001China College of Materials Science and Engineering Heilongjiang University of Science and TechnologyHarbin150022China

The evolution of the microstructure and mechanical properties of alloy system with nominally composition Mg-5Li-1Zn-0.5Ag-0.5Zr-xGd(x=0,1.2,2.4,3.6,4.8,6)is evaluated based on computational phase diagram and corresponding experimental *** results show that grains are significantly refined with the increase of Gd *** main phases of as-cast alloys areα-Mg,β-Li,AgLi_(2)Mg,and Mg_(3)*** the increase of Gd content,the amounts of Mg_(3)Gd phase andβ-Li phase have been *** the Gd content exceeds 3.6 wt%,Mg_(3)Gd phase precipitates in a form of the network at the grain *** precipitation ofβ-Li can be attributed to the competitive dissolution of Zn,Gd,and Li in ***,γ″is formed after the addition of Gd,which grows and transforms intoγ′with the increase of Gd *** solidification process,stacking faults are formed by solid transformation of partialα-Mg and Mg_(3)***,with the synergistic effect of Mg_(3)Gd,β-Li,andγ″(orγ′),as the Gd content increasing,the tensile strength of the alloy first increases,then decreases,and the elongation *** the content of Gd is 4.8 wt%,the ultimate tensile strength and yield strength reach the maximum values of 227 MPa and 139 MPa,and the elongation is 18.1%,respectively.

关键词： Mg-Li-Zn-Gd alloy Phase diagram Microstructure evolution Mechanical properties

Strain-promoted S-arylation and alkenylation of sulfinamides using arynes and cyclic alkynes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第3期67卷 928-935页

作者： Xi Zou Boming Shen Gao-lin Li qian Liang Yanhua Ouyang binghe Yang Peiyuan yu bing Gao State Key Laboratory of Chemo/Bio-Sensing and Chemometrics College of Chemistry and Chemical EngineeringInstitute of Chemical Biology and NanomedicineHunan UniversityChangsha 410082China Department of Chemistry and Shenzhen Grubbs Institute Guangdong Provincial Key Laboratory of CatalysisSouthern University of Science and TechnologyShenzhen 518055China

The conversion of commercially available chiral sulfinamides into pharmaceutically useful chiral sulfoximines via direct SIVfunctionalization is synthetically attractive but challenging due to the competitive reaction of N-functionalization. Herein, we disclose a novel strain-release strategy to access stereospecific and chemoselective SIV-arylation and alkenylation of sulfinamides using arynes and strained cyclic alkynes. This method tolerates an unprecedented chemical diversity of functional groups attached to the nitrogen center(N-R). The origin of the high SIV-selectivity is elucidated by density functional theory calculations, suggesting a stepwise mechanism for the aryne substrates and a concerted mechanism for the cyclic alkynes.

关键词： arylation alkenylation sulfoximines sulfinamides arynes

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting

在线全文

学校读者我要写书评

暂无评论

Frontiers in Energy 2024年第3期18卷 378-389页

作者： Zhao-ting SHANG Tang-ming LI bing-qian HU Min LIU Wang-ting LU Fan yu yun ZHENG Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education College of Optoelectronic Materials and TechnologyJianghan UniversityWuhan 430056China Institute of New Energy Materials and Engineering School of Materials Science and EngineeringFuzhou UniversityFuzhou 350108China Department of Chemical Engineering University of WaterlooWaterlooOntario N2L 3G1Canada

The use of two-dimensional(2D)layered metal-organic frameworks(MOFs)as self-sacrificial templates has been proven to be a successful method to create high-efficiency Selenium(Se)-containing electrocatalysts for overall water ***,two strategies are then utilized to introduce Se element into the Co–Fe MOF,one being the etching of as-prepared MOF by SeO_(2) solution,and the other,the replacing of SCN−with SeCN−as the construction *** electrochemical activity of the pristine 2D MOF and their calcinated derivatives for catalyzing the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is evaluated and further *** is found that the effect of introducing Se on improving electrochemical catalytic activity is significant for the HER ***,the calcinated derivative in the replacing method exhibits an overpotential of 235 mV for HER and 270 mV for OER at a current density of 10 mA/*** comparing the two methods of introducing Se element into MOF,similar electrocatalytic activity can be achieved on the their calcinated *** high electrochemical performance of 2D CoFe-MOF derivatives may be resulted from the unique 2D hierarchical porous structure and strong synergistic effect between different components in the material.

关键词： 2D MOF selenium(Se)-containing materials hydrogen evolution reaction(HER) oxygen evolution reaction(OER)

Therapeutic potential of dental pulp stem cell transplantation in a rat model of Alzheimer’s disease

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2021年第5期16卷 893-898页

作者： Xue-Mei Zhang yuan-Jiao Ouyang bing-qian yu Wei Li Mei-yu yu Jin-yue Li Zhuo-Min Jiao Dan Yang Na Li Ying Shi yun-yun Xu Zhi-Jun He Duo Wang Hui yue Jin Fu Department of Neurology The 2nd Affiliated Hospital of Harbin Medical UniversityHarbinHeilongjiang ProvinceChina Department of Neurology Ningbo Hangzhou Bay HospitalNingboZhejiang ProvinceChina Department of Neurology the First Hospital of QiqiharQiqiharHeilongjiang ProvinceChina

Dental pulp stem cells are dental pulp-derived mesenchymal stem cells that originate from the neural *** exhibit greater potential for the treatment of nervous system diseases than other types of stem cells because of their neurogenic differentiation capability and their ability to secrete multiple neurotrophic *** studies have reported Alzheimer’s disease treatment using dental pulp stem *** models of Alzheimer’s disease were established by injecting amyloid-β1–42 into the *** days later,5×106 dental pulp stem cells were injected into the *** and western blot assays showed that dental pulp stem cell transplantation increased the expression of neuron-related doublecortin,NeuN,and neurofilament 200 in the hippocampus,while the expression of amyloid-βwas ***,cognitive and behavioral abilities were *** findings indicate that dental pulp stem cell transplantation in rats can improve cognitive function by regulating the secretion of neuron-related proteins,which indicates a potential therapeutic effect for Alzheimer’s *** study was approved by the Animal Ethics Committee of Harbin Medical University,China(approval ***2017-132)on February 21,2017.

关键词： Alzheimer’s disease brain central nervous system dental pulp stem cell in vivo model rat stem cells transplantation

BLS-identification:A device fingerprint classification mechanism based on broad learning for Internet of Things

在线全文

学校读者我要写书评

暂无评论

Digital Communications and Networks 2024年第3期10卷 728-739页

作者： yu Zhang Bei Gong qian Wang Faculty of Information Technology Beijing University of TechnologyBeijing100124China School of Information Science and Technology Zhengzhou Normal UniversityHenan450044China

The popularity of the Internet of Things(IoT)has enabled a large number of vulnerable devices to connect to the Internet,bringing huge security *** a network-level security authentication method,device fingerprint based on machine learning has attracted considerable attention because it can detect vulnerable devices in complex and heterogeneous access ***,flexible and diversified IoT devices with limited resources increase dif-ficulty of the device fingerprint authentication method executed in IoT,because it needs to retrain the model network to deal with incremental features or *** address this problem,a device fingerprinting mechanism based on a Broad Learning System(BLS)is proposed in this *** mechanism firstly characterizes IoT devices by traffic analysis based on the identifiable differences of the traffic data of IoT devices,and extracts feature parameters of the traffic packets.A hierarchical hybrid sampling method is designed at the preprocessing phase to improve the imbalanced data distribution and reconstruct the fingerprint *** complexity of the dataset is reduced using Principal Component Analysis(PCA)and the device type is identified by training weights using *** experimental results show that the proposed method can achieve state-of-the-art accuracy and spend less training time than other existing methods.

关键词： Device fingerprint Traffic analysis Class imbalance Broad learning system Access authentication

HEAT KERNEL ON RICCI SHRINKERS(II)

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2024年第5期44卷 1639-1695页

作者： yu LI bing WANG Institute of Geometry and Physics University of Science and Technology of ChinaHefei230026China Hefei National Laboratory Hefei230088China

This paper is the sequel to our study of heat kernel on Ricci shrinkers[29].In this paper,we improve many estimates in[29]and extend the recent progress of Bamler[2].In particular,we drop the compactness and curvature boundedness assumptions and show that the theory of F-convergence holds naturally on any Ricci flows induced by Ricci shrinkers.

关键词： Ricci flow Ricci shrinker heat kernel

A Strong,Tough,and Self-Healing Strengthening Thioctic Acid-based Elastomer for Highly Reliable Flexible Strain Sensor

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第10期42卷 1610-1618,I0016页

作者： Xin-yu Chen yu-bing Fu Xue-Ling Yan Lan Liu School of Materials Science and Engineering Key Lab of Guangdong Province for High Property and Functional Polymer MaterialsSouth China University of TechnologyGuangzhou510641China

Elastomers with high strength and toughness,excellent self-healing properties,and biocompatibility have broad application prospects in wearable electronics and other fields,but preparing it remains a *** this work,we propose a highly adaptable strategy by introducing the small molecule crosslinking agent of triethanolamine(TEA)to the poly(thioctic acid)(PTA)chains and preparing the PAx Ey elastomers using a simple synthesis *** strategy stabilizes the PTA chains by constructing multiple non-covalent cross-linked dynamic networks,endowing materials with excellent strength and toughness(tensile strength of 288 kPa,toughness of 278.2 kJ/m3),admirable self-healing properties(self-healing efficiency of 121.6%within 7 h at 70℃),and good *** PAx Ey elastomers can also be combined with MWNTs to become flexible strain sensors,which can be used to monitor human joint movements with high sensitivity,repeatable responses,and stability.

关键词： Thioctic acid Ion clusters Multiple dynamic networks Self-healing strengthening Flexible strain sensor

Biomimetic chitin hydrogel via chemical transformation

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第2期17卷 771-777页

作者： Rui-Rui Liu qian-qian Shi yu-Feng Meng Yong Zhou Li-Bo Mao Shu-Hong yu Division of Nanomaterials&Chemistry Hefei National Research Center for Physical Sciences at the MicroscaleDepartment of ChemistryInstitute of Biomimetic Materials&ChemistryAnhui Engineering Laboratory of Biomimetic MaterialsUniversity of Science and Technology of ChinaHefei 230026China College&Hospital of Stomatology Key Laboratory of Oral Diseases Research of Anhui ProvinceAnhui Medical UniversityHefei 230032China Department of Dental Implantology College&Hospital of StomatologyAnhui Medical UniversityHefei 230032China

Chitin hydrogel has been recognized as a promising material for various biomedical applications because of its biocompatibility and ***,the fabrication of strong chitin hydrogel remains a big challenge because of the insolubility of chitin in many solvents and the reduced chain length of chitin regenerated from *** herein introduce the fabrication of chitin hydrogel with biomimetic structure through the chemical transformation of chitosan,which is a water-soluble deacetylated derivative of *** reacetylation of the amino group in chitosan endows the obtained chitin hydrogel with outstanding resistance to swelling,degradation,extreme temperature and pH conditions,and organic *** chitin hydrogel has excellent mechanical properties while retaining a high water content(more than 95 wt.%).It also shows excellent antifouling performance that it resists the adhesion of proteins,bacteria,blood,and ***,as the initial chitosan solution can be feasibly frozen and templated by ice crystals,the chitin hydrogel structure can be either nacre-like or wood-like depending on the freezing method of the precursory chitosan *** to these anisotropic structures,such chitin hydrogel can exhibit anisotropic mechanics and mass transfer *** current work provides a rational strategy to fabricate chitin hydrogels and paves the way for its practical applications as a superior biomedical material.

关键词： chitin hydrogel biomimetic structure chemical stability mechanical strength antifouling