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SYNTHESIS AND THERMAL STABILITY Of NANOCOMPOSITE nc-TiN/a-TiB_2 THIN fILMS

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 307-312页

作者： Y.H.Lu z.f.zhou P.Sit Y.G.Shen K.Y.Li H.Chen DepartmentofPhysicsandMaterialsScience CityUniversityofHongKongKowloonHongKongChina／／DepartmentofManufacturingEngineeringg~EngineeringManagementCityUniversityofHongKongKowloonHongKongChina DepartmentofManufacturingEngineering＆EngineeringManagement CityUniversityofHongKongKowloonHongKongChina DepartmentofPhysicsandMaterialsScience CityUniversityofHongKongKowloonHongKongChina

Several nc-TiN/a-TiB2 thin films comprised of nanocrystalline (nc-) TiN and amor phous (a-) TiB2 phases were deposited on Si(100) at room temperature by reactive unbalanced dc magnetron sputtering, followed by vacuum annealed at 400, 600, 80 0 and 1000℃ for 1h, respectively. Effects of B content on microstructure, mecha nical behaviors and thermal microstructure stability have been investigated by X -ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and nanoindentation measurements. The results indicated that B addition greatly affected both microstructure and mechanical behavior of nc-Ti N/a-TiB2 thin films. With increasing B content the grain size decreased. A maxim um hardness value of about 33GPa was obtained at B content of about 19at.%. The improved mechanical properties of nc-TiN/a-TiB2 films with the addition of B int o TiN were attributed to their densified microstructure with development of fine grain size. Only addition of sufficient B could restrain grain growth during an nealing. High B content resulted in high microstructure stability. The crystalli zation of amorphous matrix occurred at about 800℃, forming TiB or TiB2 crystall ite, depending on B content. Before that no change in bonding configuration was found.

关键词： annealing boron reactive unbalanced dc magnetron sputtering ther mal stability nc-TiN/a-TiB2 thin film

COMPOSITION EffECT ON DRY SLIDING WEAR BEHAVIORS Of Ti-B-N THIN fILMS

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 300-306页

作者： P.Sit Y.H.Lu H.Chen z.f.zhou Y.G.Shen K.Y.Li DepartmentofPhysicsandMaterialsScience CityUniversityofHongKongKowloonHongKongChina DepartmentofPhysicsandMaterialsScience CityUniversityofHongKongKowloonHongKongChina／／DepartmentofManufacturingEngineeringg：EngineeringManagementCityUniversityofHongKongKowloonHongKongChina DepartmentofManufacturingEngineering＆EngineeringManagement CityUniversityofHongKongKowloonHongKongChina

friction and sliding wear behaviour of Ti-B-N coatings against AISI440C steel ba ll and WC-6wt%Co ball were studied by using pin-on-disk tribometer along with mi crostructure characterization using optical microscopy (OM), scanning electron m icroscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It is shown that the wear resistance of film depended on the wear mechanism. In the case of AISI440C steel, adhesive wear were pre-dominant and the wear rate increased sharply to a maximum when N content reach ~38at.%. This might be related to the change of fi lm microstructure and phase configuration, so the least adhesive transfer of tri bo-film was observed. If WC-6wt%Co ball was used, less deformation wear debris w as observed, this was responsible for the rise of wear rate. Despite of differen t wear modes, friction coefficients in both cases were found to depend mainly on the formation and the amount of h-BN phase. Elemental analysis by energy disper sive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) revealed that oxygen participated in the wear behavior by reacting with films to form the deb ris comprised of various types of Ti oxide including TiO, TiO2 and Ti2O3 , which increased wear resistance.

关键词： dry sliding wear friction coefficient oxidation Ti-B-N wear

TRIBOLOGICAL AND HIGH SPEED TURNING PERfORMANCE IN Ti_(1-x)Al_(x)N COATINGS PREPARED BY CLOSE-fIELD UNBALANCED MAGNETRON SPUTTERING

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 254-260页

作者： P.W.Shum M.Escursell T.H.Wong K.Y.Li z.f.zhou Y.G.Shen Advanced Coatings Applied Research Laboratory(ACARL) Department of Manufacturi ng Engineering and Engineering ManagementCity University of Hong KongKowloonHong KongChina

Titanium-aluminium-nitride(Ti_(1-x)Al_(x)N)coatings were deposited by close-field un balanced magnetron sputtering on M42 steel substrates and WC-6wt%Co inserts at 450℃.The tribological behavior was analyzed by sliding against steel and WC-6wt%Co balls,while the turning performance was evaluated by a conventional tu rning machine at high cutting speeds without using *** the tribological tests,the formation of transfer layer and the variations of hardness of the co atings played an important role for sliding against steel *** the coating s sliding against WC-6wt%Co balls,the Ti-Al-N coatings showed a similar frictio n coefficient,but the TiN coating exhibited a lower *** difference could be explained by the tri-oxidation wear *** the turning tests,a super ior cutting performance of the coating was found at x=0.45,which endured 38 min utes before the tool flank wear reached the maximum value of 0.3mm,whereas only 20 minutes were endured for the TiN *** excellent performance of the c oatings in the turning tests could be explained by the enhanced mechanical prope rties and oxidation/diffusion resistance of the coatings.

关键词： hardness Ti-Al-N coating tribology turning test wear test

The Size Dependence of Neel Temperature

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The Size Dependence of Neel Temperature

Precipitation of multi-type nano-quasicrystals in a Mg-zn-Y alloy

第十三届全国物理力学学术会议

作者： W.zhang z.f.zhou C.Q.Sun Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education) and faculty of Materials Optoelectronics and PhysicsXiangtan University

Broad research effort has been underway to study Antiferromagnetic(AfM)low-dimensional materials,However,The inherent mechanism of thermal properties of low dimensional magnetic nanomaterials is still *** paper mainly report the different properties between the surface and interface under small size and the *** on the BOLS correlation mechanism,We build an analytic and simple model for the size and interface coupling effects on the thermal stability of AfM nanocrystals model to explore magnetic material interface coupling effect under epitaxial growth and surface effect.

关键词： Neel Temperature Antiferromagnet BOLS epitaxial growth

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Journal of Magnesium and Alloys 2024年第3期12卷 997-1008页

作者： W.z.Wang X.z.zhou L.f.zhang H.Q.Ye z.Q.Yang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of ScienceShenyang 110016China Ji Hua Laboratory Foshan 528251China foshan University Foshan 528231China

Mg-6zn-1Y(at.%)ribbons with strengthening precipitates of multi-type nanoquasicrystals were prepared by melt-spinning followed by aging *** evolution of the rapidly solidified ribbons during isothermal aging was comprehensively studied using various electron microscopy *** new kinds of decagonal quasicrystals were formed in aged ribbons,in addition to precipitation of nanometer icosahedral ***-resolution observations reveal that both decagonal quasicrystals can be modeled by quasiperiodic tiling with decagonal clusters of 2.5 nm in diameter,but overlap of neighboring clusters in both decagonal quasicrystals is different from the Gummelt model observed in other quasicrystals.A shell composed of complex Laves Mg-zn domains was formed surrounding each decagonal quasicrystal precipitate upon prolonged *** addition,all kinds of nanoprecipitates exhibit excellent structure and size stability at 573 *** findings may have implications for not only fundamental studies about quasicrystals,but also microstructural manipulation of high-performance Mg alloys.

关键词： Quasicrystal Mg alloys Rapid solidification Scanning-transmission electron microscopy.

CORRELATION BETWEEN THE ELASTIC AND THE VIBRONIC BEHAVIOR Of NANOSTRUCTURED TITANIA AND THEIR PRESSURE,SIzE,AND TEMPERATURE DEPENDENCE

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Journal of Advanced Dielectrics 2011年第4期1卷 407-416页

作者： X.J.LIU L.K.PAN z.SUN Y.M.CHEN X.X.YANG L.W.YANG z.f.zhou CHANG Q.SUN Engineering Research Center for Nanophotonics&Advanced Instrument Ministry of Education Department of Physics East China Normal University Shanghai 200062P.R.China Institute for Quantum Engineering and Micro-Nano Energy Technology Key Laboratory of Low-Dimensional Materials and Application Technology and faculty of Materials and Optoelectronic Physics Xiangtan University Hunan 411105P.R.China School of Electrical and Electronic Engineering Nanyang Technological University Singapore 639798 Singapore

Correlation bet ween the elastic and the vibronic behavior of TiO_(2) and their responses to thevariation of crystal size,applied pressure,and measuring temperature has been investig ated basedon the bond order-length-strength correlation *** reproduction of themeasurements clarified that.(i)the elastic modulus(B)and the Raman shifts(△ω)are stronglycorrelated and we can know either one of the B or the △ω from the other;(i)the under-coordination induced cohesive energy loss and the energy density gain in the surface up to skindepth determines the size effect;(ii)bond expansion and bond weakening due to thermalvibration originat es the thermally softened elastic modulus and the Raman shifts;and(iv)bondcompression and bond strengthening results in the mechanically stiffened elastic modulus and theRaman *** the developed premise,one can predict the changing trends of the concernedproperties with derivatives of quantitative information of the atomic cohesive energy,bindingenergy density,Debye tempera ture,and nonlinear compressibility of the specimen.

关键词： TiO_(2)nanostructures elasticity Ramanshift pressure temperature

Structural basis for polyuridine tract recognition by SARS-CoV-2 Nsp15

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Protein & Cell 2024年第7期15卷 547-552页

作者： fumiaki Ito Hanjing Yang z.Hong zhou Xiaojiang S.Chen Molecular and Computational Biology Department of Biological SciencesUniversity of Southern CaliforniaLos AngelesCA 90089United States Department of Microbiology Immunology and Molecular GeneticsUniversity of CaliforniaLos AngelesCA 90095United States California NanoSystems Institute University of CaliforniaLos AngelesCA90095United States Genetic Molecular and Cellular Biology ProgramKeck School of MedicineUniversity of Southern CaliforniaLos AngelesCA 90089United States Norris Comprehensive Cancer Center University of Southern CaliforniaLos AngelesCA 90089United States Center of Excellence in NanoBiophysics University of Southern CaliforniaLos AngelesCA 90089United States

Dear Editor,Coronaviruses have evolved a wide array of tactics to evade host antiviral *** host cells detect invading foreign nucleic acids including viral genome and viral replication intermediates,they activate interferon(IfN)signaling via cytoplasmic pattern recognition receptors(Kang et al.,2002;Kato et al.,2006).Remarkable stealth activities exhibited by coronaviruses are facilitated by a series of non-structural proteins(Nsps),such as Nsp15(Deng and Baker,2018;Deng et al.,2019;Hackbart et al.,2020),which is a uridine-specific endoribonuclease that mediates evasion of host detection of viral double-stranded RNA(dsRNA)(Bhardwaj et al.,2004;Deng et al.,2017;frazier et al.,2021;Ivanov et al.,2004).Nsp15 targets a polyuridine[poly(U)]tract on the coronavirus negative strand RNA(Hackbart et al.,2020).Nsp15 limits the abundance and length of poly(U)within the negative strand RNA 5ʹ-extension by trimming down the initially synthesized poly(U)lead sequence to the optimal length that can suppress dsRNA formation but still serves as a template for poly(A)tail of the positive strand genome of the coronaviruses(Hofmann and Brian,1991).

关键词： p15 interferon template

In situ digital testing method for quality assessment of soft soil improvement with polyurethane

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1732-1748页

作者： X.f.Wang C.J.Wang W.V.Yue z.J.zhang z.Q.Yue Department of Civil Engineering China University of Geosciences (Beijing)BeijingChina Department of Water Science and Engineering Zhengzhou UniversityZhengzhouChina Department of Geotechnical Engineering Tongji UniversityShanghaiChina Department of Civil Engineering The University of Hong KongChina

This study purposes an in situ testing method on quality assessment of soil *** drilling data includes the spatial distribution and in situ strength of untreated and treated soil along three different drillholes measured by on-site drilling monitoring *** factual drilling data can characterize the degree of soil improvement by penetration injection with permeable *** from on-site drilling monitoring shows that the linear zones represent constant drilling speeds shown in the plot of drill bit advancement *** drilling time,which indicates the spatial distributions of soil *** soil profile at the study site is composed of four layers,which includes fill,untreated silty clay,treated silty clay,and mucky *** results of soil profile are verified by the parallel site *** constant drilling speeds profile the coring-resistant strength of drilled *** comparing with the untreated silty clay,the constant drilling speeds of the treated silty clay have been decreased by 13.0-62.8%.Two drilling-speed-based indices of 61.2%and 65.6%are proposed to assess the decreased average drilling speed and the increased in situ strength of treated silty *** tests,*** compressive strength(UCS)test,have been performed with core sample to investigate and characterize in situ strength by comparing that with drilling *** show that the average predicted strengths of treated silty clay are 2.4-6.9 times higher than the average measured strength of untreated silty *** UCS-based indices of 374.5%and 344.2%verified the quality assessment(QA)results by this new in situ *** method provides a cost-effective tool for quality assessment of soil improvement by utilizing the digital drilling data.

关键词： Drilling process monitoring system Hydraulic rotary drilling process Constant drilling speed Soil improvement Quality assessment

The construction management informationization practice in Shanghai Yangtze River Tunnel & Bridge Project

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The construction management informationization practice in S...