检索结果-南通市图书馆

Creep-Resistant Covalent Adaptable Networks with Excellent SelfHealing and Reprocessing Performance via Phase-Locked Dynamic Covalent Benzopyrazole-Urea Bonds

在线全文

维普期刊数据库

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 1545-1556,I0013页

作者： miao Xie xiao-Rong wang Zhan-Hua wang He-Sheng Xia State Key Laboratory of Polymer Materials Engineering Polymer Research InstituteSichuan UniversityChengdu610065China School of Petrochemical Engineering Liaoning Petrochemical UniversityFushun113001China

Covalent adaptive networks(CANs)are capable of undergoing segment rearrangement after being heated,which endows the materials with excellent self-healing and reprocessing performance,providing an efficient solution to the environment pollution caused by the plastic *** main challenge remains in developing CANs with both excellent reprocessing performance and creep-resistance *** this study,a series of CANs containing dynamic covalent benzopyrazole-urea bonds were developed based on the addition reaction between benzopyrazole and isocyanate *** calculation confirmed that relatively low dissociation energy is obtained through undergoing a five-member ring transition state,confirming excellent dynamic property of the benzopyrazole-urea *** verified by the FTIR results,this nice dynamic property can be well maintained after incorporating the benzopyrazole-urea bonds into polymer *** self-healing and reprocessing performance is observed by the 3-ABP/PDMS elastomers owing to the dynamic benzopyrazole-urea *** separation induced by the aggregation of the hard segments locked the benzopyrazole-urea bonds,which also makes the elastomers display excellent creep-resistance *** hard phase locking strategy provides an efficient approach to design CANs materials with both excellent reprocessing and creep-resistance performance.

关键词： Covalent adaptive networks Self-healing polymer Dynamic covalent bond

Improvement of enamel bond strengths for conventional and resin-modified glass ionomers: acid-etching vs. conditioning

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2013年第11期14卷 1013-1024页

作者： Ling ZHANG Tian TANG Zhen-liang ZHANG Bing LIANG xiao-miao wang Bai-ping FU Hospital of Stomatology Affiliated to Zhejiang University School of Medicine

Objective:This study deals with the effect of phosphoric acid etching and conditioning on enamel micro-tensile bond strengths(μTBSs)of conventional and resin-modified glass ionomer cements(GICs/RMGICs).Methods:Forty-eight bovine incisors were prepared into rectangular ***-polished labial enamel surfaces were either acid-etched,conditioned with liquids of cements,or not further treated(control).Subsequently,two matching pre-treated enamel surfaces were cemented together with one of four cements[two GICs:Fuji I(GC),Ketac Cem Easymix(3M ESPE);two RMGICs:Fuji Plus(GC),RelyX Luting(3M ESPE)]in preparation forμTBS ***-treated enamel surfaces and cement-enamel interfaces were analyzed by scanning electron microscopy(SEM).Results:Phosphoric acid etching significantly increased the enamelμTBS of GICs/*** with the liquids of the cements produced significantly weaker or equivalent enamelμTBS compared to the *** of etching,RMGICs yielded stronger enamelμTBS than GICs.A visible hybrid layer was found at certain enamelcement interfaces of the etched ***:Phosphoric acid etching significantly increased the enamelμTBSs of GICs/*** acid etching should be recommended to etch the enamel margins before the cementation of the prostheses such as inlays and onlays,using GICs/RMGICs to improve the bond *** provided stronger enamel bond strength than GICs and conditioning did not increase enamel bond strength.

关键词： Glass ionomer cements Surface treatments Bovine enamels Scanning electron microscopy(SEM) Micro-tensile bond strengths

The Spectrum of (gv, g, 3, λ)-dDF in Zgv

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2010年第2期26卷 377-392页

作者： xiao miao wang Yan Xun CHANG Institute of Mathematics, Beijing Jiaotong University, Beijing 100044, P. R. China Institute of Mathematics Beijing Jiaotong University Beijing P. R. China

In this paper, several recursive constructions for directed difference family and perfectdirected difference family are presented by means of difference matrix and incomplete difference *** the necessary and sufficient conditions for the existence of a (gv, g, 3, λ)-directed differencefamily in Zare established. As a consequence, the necessary and sufficient conditions for the existenceof a cyclic directed group divisible design with block size three and type g~v are obtained.

关键词： directed difference family incomplete difference matrix perfect directed difference family

A global model for evaluating discharge characteristics and performance of hollow cathodes

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

CHINESE JOURNAL OF AERONAUTICS 2024年第9期37卷 72-84页

作者： Tian, Feng miao, Long Xia, Qimeng Wu, Zhiwen wang, Ningfei Hou, xiao Beijing Inst Technol Sch Aerosp Engn Beijing 100081 Peoples R China Beijing Inst Technol Chongqing Innovat Ctr Chongqing 404100 Peoples R China

Hollow cathode, with the highest plasma density, current density, and temperature, becomes one of the most important components in the electro-thruster system. As the electric-propulsion thruster performance is directly related to the ionization rate, reliability, and lifetime of the hollow cathode, this paper develops a global model to study the effects of discharge current, gas flow rate, and gas species on the discharge characteristics in the insert and orifice regions of the hollow cathode. The emitter wall temperatures of hollow cathodes predicted by the global model are compared with experimental results from NSTAR thruster neutralization cathodes, confirming the model's validity. The influence of hollow cathode emitter material and structure sizes on the plasma parameters in the internal regions was also evaluated. The simulation results show that there is an optimal matching relationship between the discharge current and gas flow rate to guarantee the maximum ionization rate. The optimal working region for the hollow cathode has been determined under different energetic, regime and structural parameters. The global model established in this paper can quickly determine the key structure and operating parameters of hollow cathode at the design stage, and provide the theoretical basis for hollow cathode design and development. (c) 2024 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics. This is an open access article under the CC BY-NC-ND license (http://***/ licenses/by-nc-nd/4.0/).

关键词： Hollow cathode Global model Electric propulsion Discharge characteristics Optimal matching relationship ION PROPULSION SIMULATION

Boosting spring runoff into the sea by reservoir regulation and its potential for estuarine fishery recovery

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 Earth Sciences 2024年第5期67卷 1591-1603页

作者： xiao WU Houjie wang Yongyong FAN Naishuang BI Chiyuan miao Jingping XU Zuosheng YANG College of Marine Geosciences Key Laboratory of Submarine Geosciences and Prospecting Technologyand Frontiers Science Center for Deep Ocean Multispheres and Earth SystemOcean University of ChinaQingdao 266100China Laoshan National Laboratory Qingdao 266061China Institute of the Yellow River Estuary and Coast Science Dongying 257000China State Key Laboratory of Earth Surface Processes and Resource Ecology Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China Department of Ocean Science&Engineering Southern University of Science and TechnologyShenzhen 518055China

With global surge in reservoir construction over the past decades,river systems worldwide have been profoundly ***,flow manipulation by reservoirs has altered the natural hydrological processes,resulting in extensive modifications of fluvial-marine *** the adverse ecological consequences of reservoirs has become a global concern and has garnered increasing *** Yellow River,as one of the most extensively manipulated river systems globally,has experienced substantial changes in the amount and timing of water discharge due to the presence of numerous reservoirs scattered throughout its catchment *** alterations have caused physicochemical changes in the estuary and subsequent modifications to the estuarine *** recent years,the Yellow River Conservancy Committee initiated the release of water through the xiaolangdi Dam during the major spawning period of fisheries,specifically in the spring,with the aim of improving the estuarine ecological *** 2011 to 2020,a total of 84.05 km^(3)of water was discharged from the xiaolangdi Reservoir during spring seasons,of which 40%(33.16 km^(3))constituted water impounded within the reservoir during preceding ***,the spring water discharge from the Yellow River to the sea increased significantly from 1.50 km^(3)/yr to 3.46 km^(3)/yr in the past decade,leading to a decrease in estuarine salinity by 1.6 *** estuarine fishery resources,such as fish eggs in the Yellow River estuary,have demonstrated evident *** reservoir regulation in the Yellow River,which has successfully enhanced spring water discharge and subsequently restored estuarine fishery resources,presents an effective attempt for mitigating the adverse ecological effects associated with reservoirs.

关键词： Reservoir regulation Water release Spring runoff Estuarine ecosystem Yellow River

Multi-junction cascaded vertical-cavity surface-emitting laser with a high power conversion efficiency of 74%

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2024年第3期13卷 555-565页

作者： Yao xiao Jun wang Heng Liu Pei miao Yudan Gou Zhicheng Zhang Guoliang Deng Shouhuan Zhou College of Electronics and Information Engineering Sichuan UniversityChengdu 610064China Suzhou Everbright Photonics Co. LtdSuzhou 215163China

High electro-optical conversion efficiency is one of the most distinctive features of semiconductor lasers as compared to other types of *** further increase remains a significant *** enhancing the efficiency of edgeemitting lasers(EEL),which represent the highest efficiency among semiconductor lasers at present,is *** efficiency of vertical cavity surface emitting lasers(VCSELs)has always been relatively low compared to *** paper,combining modeling with experiments,demonstrates the potential of multi-junction cascaded VCSELs to achieve high efficiency beyond that of EELs,our simulations show,that a 20-junction VCSEL can achieve an efficiency of more than 88%at room *** fabricated VCSEL devices with different numbers of junctions and compared their energy efficiency.15-junction VCSELs achieved a maximum efficiency of 74%at room temperature under nanosecond driving current,the corresponding differential quantum efficiency exceeds 1100%,being the largest electro-optical conversion efficiency and differential quantum efficiency reported until now for VCSELs.

关键词： cascaded power cavity

A surgical alternative of fusiform penetrating keratoplasty for the management of severe infectious keratitis

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Ophthalmology(English edition) 2024年第8期17卷 1431-1436页

作者： xiao-Lin Qi Li-Chao wang miao-Lin wang Hua Gao Eye Hospital of Shandong First Medical University State Key Laboratory Cultivation BaseShandong Provincial Key Laboratory of OphthalmologyShandong Eye InstituteShandong First Medical University&Shandong Academy of Medical SciencesJinan 250021Shandong ProvinceChina

AIM:To describe the surgical procedure of fusiform penetrating keratoplasty(FPK)using multiple trephines of different sizes for treating patients with severe infectious ***:Fourteen eyes underwent FPK,and 15 eyes received conventional penetrating keratoplasty(PK)were included in the *** best-corrected visual acuity(BCVA),refractive outcomes,endothelial cell density,and postoperative complications were ***:The FPK group was followed for an average of 15.3±2.1mo,whereas the PK group was followed for 16.1±*** corneal ulcers were elliptical-shaped in all 14 eyes in the FPK *** mean BCVA(logMAR,0.26±0.13)showed no statistically significant differences from that in the PK group(logMAR,0.21±0.12,P>0.05)at 1y after *** the mean curvature,mean astigmatism,and mean spherical equivalent in the FPK group were lower than those in the PK group(P<0.05).Peripheral anterior synechia was observed in one patient in the FPK group,whereas 6 patients in the PK *** loosening and neovascularization were observed in 4 and 5 eyes in the PK group,*** graft immune rejection or elevation of intraocular pressure was observed in the two ***:For patients with elliptical-shaped corneas or corneal ulcers,FPK can avoid disrupting of corneal limbus,reduce the risk of postoperative complications,and can result in satisfactory visual quality.

关键词： fusiform penetrating keratoplasty multiple trephines infectious keratitis cornea

Recent advances in Pt catalysts and membrane electrode assemblies fabrication for proton exchange membrane fuel cells

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第9期43卷 4198-4221页

作者： miao Ma Li-xiao Shen Jing Liu Bin Xu Yun-Long Zhang Lei Zhao Zhen-Bo wang School of Chemistry and Chemical Engineering Harbin Instituteof Technology College of Environmental and Chemical Engineering YanshanUniversity Unipower Hydrogen Technology (Jiangsu) Corporation

Proton exchange membrane fuel cells(PEMFCs) have been identified as a highly promising means of achieving sustainable energy conversion. A crucial factor in enhancing the performance of PEMFCs for further potential energy applications is the advancement in the field of catalyst engineering that has led to remarkable performance enhancement in facilitating the oxygen reduction reaction(ORR). Subsequently, it is important to acknowledge that the techniques used in preparation of membrane electrode assemblies(MEAs), the vital constituents of PEMFCs, also possess direct and critical influence on exhibiting the full catalytic activity of meticulously crafted catalysts. Here, a succinct summary of the most recent advancements in Pt catalysts for ORR was offered and their underly catalytic mechanism were discussed. Then, both laboratory-scale and industrial-scale MEA fabrication techniques of Pt catalysts were summarized. Furthermore, a detailed analysis of the connections between materials, process, and performance in MEA fabrication was presented in order to facilitate the development of optimal catalyst layers.

关键词： MEA fabrication techniques Membrane electrode assemblies Oxygen reduction reaction Pt catalysts

Multifunctional Integrated Organic-Inorganic-Metal Hybrid Aerogel for Excellent Thermal Insulation and Electromagnetic Shielding Performance

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nano-Micro Letters 2024年第10期16卷 163-175页

作者： Zhaoqi Niu Fengjin Qu Fang Chen xiaoyan Ma Beixi Chen Luyao wang miao Xu Shumeng wang Liang Jin Chengshuang Zhang xiao Hou Ministry of Industry and Information Technology Key Laboratory of Special Function and Smart Polymer Materials Key Laboratory of Materials Physics and Chemistry of Ministry of Education for Extraordinary ConditionsNorthwestern Polytechnical UniversityXi'an 710072People's Republic of China Spallation Neutron Source Science Center Institution Dongguan 523803People's Republic of China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049People's Republic of China China Aerospace Science and Industry Corporation Sixth Academy Hohhot 022185People's Republic of China Xi'an Aerospace Composites Research Institute Xi'an 710025People's Republic of China China Aerospace Science and Technology Corporation Beijing 100037People's Republic of China

Vehicles operating in space need to withstand extreme thermal and electromagnetic environments in light of the burgeoning of space science and *** is imperatively desired to high insulation materials with lightweight and extensive mechanical ***,a boron-silica-tantalum ternary hybrid phenolic aerogel(BSiTa-PA)with exceptional thermal stability,extensive mechanical strength,low thermal conductivity(49.6 mW m^(-1)K^(-1)),and heightened ablative resistance is prepared by an expeditious *** extremely thermal erosion,the obtained carbon aerogel demonstrates noteworthy electromagnetic interference(EMI)shielding performance with an efficiency of 31.6 dB,accompanied by notable loading property with specific modulus of 272.8 kN·m kg^(-1).This novel design concept has laid the foundation for the development of insulation materials in more complex extreme environments.

关键词： Multi-hybrid aerogel Metal-phenolic coordination Thermal insulation EMI shielding Convertibility and multifunctionality