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In situ selective laser gas nitriding for composite TiN/Ti-6Al-4V fabrication via laser powder bed fusion

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Journal of Materials Science & Technology 2020年第10期42卷 98-107页

作者： P.A.Morton H.C.Taylor L.E.Murr O.G.Delgado C.A.Terrazas R.b.Wicker W.M.Keck Center for 3D Innovation The University of Texas at El PasoEl PasoTX79968USA Department of Mechanical Engineering The University of Texas at El PasoTX 79968USA Department of Metallurgical Materials and Biomedical EngineeringThe University of Texas at El PasoTX 79968USA

Laser-assisted gas nitriding of selective Ti-6Al-4V surfaces has been achieved during laser powder bed fusion fabrication by exchanging the argon build gas environment with *** variation of processing parameters allowed microdendritic Ti N surface coatings to be formed having thicknesses ranging from a few tens of microns to several hundred microns,with TiN dendrite microstructure volume fractions ranging from 0.6 to 0.75;and corresponding Vickers microindentation hardness values ranging from^7.5 GPa–9.5 *** TiN hard layers ranging from 50μm to 150μm thick were also fabricated in the laser-beam additively manufactured Ti-6Al-4V alloy producing prototype,hybrid,planar composites having alternating,ductile Ti-6Al-4V layers with a hardness of^4.5 GPa and a stiff,TiN layer with a hardness of^8.5 *** results demonstrate prospects for fabricating novel,additively manufactured components having selective,hard,wear and corrosion resistant coatings along with periodic,planar or complex metal matrix composite regimes exhibiting superior toughness and related mechanical properties.

关键词： Ti-6Al-4V TiN ceramic coatings and embedded layers Dendritic microstructures Selective laser melting Additive manufacturing Metal matrix composites Selective nitriding

Evaluating instrumented Charpy impact strain signals using curve fitting equations

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Journal of Central South University 2014年第2期21卷 600-609页

作者： M.b.Ali S.Abdullah M.Z.Nuawi A.K.Ariffin Z.M.Nopiah Department of Mechanical and Materials Engineering Faculty of Engineering and Built EnvironmentUniversiti Kebangsaan Malaysia Department of Structure and Material Faculty of Mechanical EngineeringUniversiti Teknikal Malaysia Melaka

An effective and simple way to develop equations from impact strain signals was *** research has been performed in this area,but this equation is very important for evaluating input signals in finite element analysis impact tests and for obtaining additional information on material deformation and fracture processes under impact *** this purpose,dynamic impact responses were examined through signals obtained from a strain gauge installed on an impact striker connected to a data acquisition *** 6061-T6 was used to extract strain responses on the striker during Charpy impact *** analysis was performed using the I-kaz method,and curve fitting equations based on the equation for vibration response under a non-periodic force were used to evaluate the Charpy impact *** I-kaz coefficients and curve fitting equations were then compared and discussed with related parameters,such as velocities and *** and thickness were found to be related to the strain signal patterns,curve fitting equations and I-kaz *** equations developed using this method had R2 values greater than 97.7%.Finally,the constructed equations were determined to be suitable for evaluating Charpy impact strain signal patterns and obtaining additional information on fracture processes under impact loading.

关键词：曲线拟合方程应变信号评估摆锤式仪器数据采集系统夏比冲击试验附加信息

A generalized Weyl-Wigner quantization scheme unifying P-Q and Q-P ordering and Weyl ordering of operators

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Chinese Physics b 2012年第6期21卷 207-212页

作者：王继锁范洪义孟祥国 Shandong Provincial Key Laboratory of Laser Polarization and Information Technology College of Physics and EngineeringQufu Normal University Department of Physics Liaocheng University Department of Physics Shanghai Jiao Tong University

by extending the usual Wigner operator to the s-parameterized one as 1/4π2 integral （dyduexp [iu（q-Q）＋iy（p-P）＋is/2yu]） from n=- ∞ to ∞ with s beng a,real parameter,we propose a generalized Weyl quantization scheme which accompanies a new generalized s-parameterized ordering *** rule recovers P-Q ordering,Q-P ordering,and Weyl ordering of operators in s = 1,1,0 *** it differs from the Cahill-Glaubers’ ordering rule which unifies normal ordering,antinormal ordering,and Weyl *** also show that in this scheme the s-parameter plays the role of correlation between two quadratures Q and *** formula that can rearrange a given operator into its new s-parameterized ordering is presented.

关键词： generalized Wigner operator generalized operator ordering rule bivariate normal dis-tribution

Science Letters:Alterations in seedling vigour and antioxidant enzyme activities in Catharanthus roseus under seed priming with native diazotrophs

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Journal of Zhejiang University-Science b(biomedicine & biotechnology) 2007年第7期8卷 453-457页

作者： KARTHIKEYAN b. JALEEL C.A. GOPI R. DEIVEEKASUNDARAM M. Department of Microbiology Faculty of Agriculture Annamalai University Annamalainagar 608 002 Tamilnadu India Stress Physiology Lab Department of Botany Annamalai University Annamalainagar 608 002 Tamilnadu India

An experiment was conducted on Catharanthus roseus to study the effect of seed treatments with native diazotrophs on its seedling growth and antioxidant enzyme activities. The treatments had significant influence on various seedling parameters. There is no significant influence on dry matter production with the diazotrophs, Azospirillum and Azotobacter. However, the vital seedling parameters such as germination percentage and vigour index were improved. Azotobacter treatment influenced maximum of 50% germination, whereas Azospirillum and Azotobacter were on par with C. roseus with respect to their vigour index. There was significant difference in the population of total diazotrophs. Azospirillum and Azotobacter between rhizosphere and non-rhizosphere soils of C. roseus had the same trend and were observed at various locations of the study. The activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT) were increased to a significant extent due to the treatment with diazotrophs.

关键词：树苗质量抗氧化剂酶活性固氮生物

Impact of leg bending in the patient-specific computational fluid dynamics of popliteal stenting

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Acta Mechanica Sinica 2021年第2期37卷 279-291页

作者： A.Ferrarini A.Finotello G.Salsano F.Auricchio D.Palombo G.Spinella b.Pane M.Conti Department of Civil Engineering and Architecture University of PaviaPaviaItaly Department of Surgical and Integrated Diagnostic Sciences University of GenoaGenoaItaly Department of Radiology IRCCS Ospedale Policlinico San MartinoGenoaItaly Vascular and Endovascular Surgery Unit IRCCS Ospedale Policlinico San MartinoGenoaItaly

Endovascular treatment of the femoro-popliteal artery has recently become a valuable therapeutic option for popliteal arterial ***,its efficacy remains controversial due to the relatively high rate of complications,such as stent occlusion as result of intra-stent *** elucidation of the interplay among vessel geometrical features,local hemodynamics,and leg bending seems crucial to understand onset and progression of popliteal intra-stent *** this aim,patient-specific computational fluid dynamic simulations were performed in order to assess the intra-stent hemodynamics of two patients endovascularly treated for popliteal arterial aneurysm by stent-grafts and experiencing intra-stent *** Newtonian and non-Newtonian blood rheological models were *** were presented in terms of tortuosity,luminal area exposed to low(1.5 Pa)time-averaged wall shear stress(TAWSS),area exposed to high(>0.3)oscillatory shear index(OSI),and flow *** outcomes demonstrated that leg bending induced significant hemodynamic differences(>50%increase)in both patients for all the considered variables,except for OSI in one of the two considered *** both leg configurations,stent-graft overlapping induced a severe discontinuity of the lumen diameter where the proximal stented zone is characterized by low tortuosity,low velocity,low helicity,low TAWSS,and high OSI;while the distal part has higher tortuosity,velocity,helicity,TAWSS,and lower *** study on applied boundary conditions showed that the different inlet velocity profiles for a given inlet waveform affect slightly the numerical solution;conversely,the shape and magnitude of the prescribed inlet waveform is *** on the comparison between the Newtonian and non-Newtonian blood models,the area with low TAWSS is greater in the Newtonian model for both patients,while no significant difference occurs between the surfaces with hig

关键词： Popliteal artery aneurysm Peripheral stenting Endovascular treatment Femoropopliteal segment Medical image analysis

PRObING THE IMPACT OF GAMMA-IRRADIATION ON THE METAbOLIC STATE OF NEURAL STEM AND PRECURSOR CELLS USING DUAL-WAVELENGTH INTRINSIC SIGNAL TWO-PHOTON EXCITED FLUORESCENCE

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Journal of Innovative Optical Health Sciences 2011年第3期4卷 289-300页

作者： TATIANA b.KRASIEVA ERICH GIEDZINSKI KATHERINE TRAN MARY LAN CHARLES L.LIMOLI bRUCE J.TROMbERG Laser Microbeam and Medical Program beckman Laser Institute University of California Irvine1002 Health Sciences Road EastIrvineCA 92612USA Department of Radiation Oncology University of California IrvineCalifornia 92697USA

Two-photon excitedfluorescence(TPEF)spectroscopy and imaging were used to investigate the effects of gamma-irradiation on neural stem and precursor cells(NSPCs).While the observed signal from reduced nicotinamide adenine dinucleotide(NADH)was localized to the mitochondria,the signal typically associated with oxidizedflavoproteins(Fp)was distributed diffusely throughout the *** measured TPEF emission and excitation spectra were similar to the established spectra of NAD(P)H and *** intensity was markedly increased by addition of the electron transport chain(ETC)modulator menadione to the medium,along with a concomitant decrease in the NAD(P)H ***-dimensional(3D)neurospheres were imaged to obtain the cellular metabolic index(CMI),calculated as the ratio of Fp to NAD(P)Hfluorescence *** effects were found to differ between low-dose(50 cGy)and high-dose(50 cGy)***-dose irradiation caused a marked drop in CMI values accompanied by increased cellular *** higher doses,both NAD(P)H and Fp signals increased,leading to an overall elevation in CMI *** underscore the complex relationship between radiation dose,metabolic state,and proliferation status in NSPCs and highlight the ability of TPEF spectroscopy and imaging to characterize metabolism in 3D spheroids.

关键词： Multiphoton microscopy cellular metabolic index gamma radiation brain tumors NAD(P)H flavoproteins

ON THEORETICAL RESULTS OF AT MOST 1-EMbEDDAbILITY OF GRAPHS

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Chinese Science bulletin 1991年第12期36卷 1054-1055页

作者：刘彦佩 P.MARCHIORO R.PETRESCHI b.SIMEONE Institute of Applied Mathematis & Institute of Mathematics Academia Sinica Beijing 100080 PRC Department of Mathematics. Department of Statistics.

Let k be a non-negative integer. A graph is said to be a k-bend graph if it is a planar graph in which each edge is represented by at most k+1 horizontal and vertical segments. A graph is called k-embeddable if it has a planar embedding which is a k-bend graph. On the k-embeddability of a graph, [1] provided the characterizations of k-embeddability, k≤3,

关键词： integer planar embedding subgraph bounds determining mentioned

Global methylation status of sperm DNA in carriers of chromosome structural aberrations

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Asian Journal of Andrology 2017年第1期19卷 117-124页

作者： Marta Olszewska Miroslawa Z barciszewska Monika Fraczek Nataliya Huleyuk Vyacheslav b chernykh Danuta Zastavna Jan barciszewski Maciej Kurpisz Department of Reproductive biology and Stem Cells Institute of Human Genetics Polish Academy of Sciences Strzeszynska 32 60-479 Poznan Poland Department of RNA biology Institute of Bioorganic Chemistry Polish Academy of Sciences Noskowskiego 12/14 61-704 Poznan Poland Institute of Hereditary Pathology Ukrainian Academy of Medical Sciences Lysenko Street 31a 79000 Lviv Ukraine Research Centre for Medical Genetics Russian Academy of Medical Sciences Moskvorechie Street 1115478 Moscow Russian Federation.

Male infertility might be clearly associated with aberrant DNA methylation patterns in human spermatozoa. An association between oxidative stress and the global methylation status of the sperm genome has also been suggested. The aim of the present study was to determine whether the global sperm DNA methylation status was affected in the spermatozoa of carriers of chromosome structural aberrations. The relationships between the 5-methylcytosine （msC） levels in spermatozoa and chromatin integrity status were evaluated. The study patients comprised male carriers of chromosome structural aberrations with reproductive failure （n = 24）, and the controls comprised normozoospermic sperm volunteers （n = 23）. The global msC level was measured using thin-layer chromatography （TLC） and immunofluorescence （IF） techniques. The sperm chromatin integrity was assessed using aniline blue （Ab） staining and TUNEL assay. The mean msC levels were similar between the investigated chromosome structural aberrations carriers （P） and controls （K）. However, sperm chromatin integrity tests revealed significantly higher values in chromosomal rearrangement carriers than in controls （P 〈 0.05）. Although the potential relationship between sperm chromatin integrity status and sperm DNA fragmentation and the msC level juxtaposed in both analyzed groups （P vs K） was represented in a clearly opposite manner, the low chromatin integrity might be associated with the high hypomethylation status of the sperm DNA observed in carriers of chromosome structural aberrations.

关键词： 5-methylcytosine chromatin integrity chromosomal rearrangement chromosome translocation global DNA methylation male infertility

Hole-doping of mechanically exfoliated graphene by confined hydration layers

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Nano Research 2015年第9期8卷 3020-3026页

作者： Tjeerd R. J. bollmann Liubov Yu. Antipina Matthias Temmen Michael Reichling Pavel b. Sorokin Inorganic Materials Science MESA+ Institute for Nanotechnology P. O. Box 217 7500AE Enschede The Netherlands Fachbereich Physik Universitat OsnabrClck BarbarastraBe 7 OsnabrClck 49076 Germany Moscow Institute of Physics and Technology Dolgoprudny 141700 Russian Federation Siberian Federal University Krasnoyarsk 660041 Russian Federation National University of Science and Technology MISiS Moscow 119049 Russian Federation

by the use of non-contact atomic force microscopy （NC-AFM） and Kelvin probe force microscopy （KPFM）, we measure the local surface potential of mechanically exfoliated graphene on the prototypical insulating hydrophilic substrate of CAF2（111）. Hydration layers confined between the graphene and the CaF2 substrate, resulting from the graphene＇s preparation under ambient conditions on the hydrophilic substrate surface, are found to electronically modify the graphene as the material＇s electron density transfers from graphene to the hydration layer. Density functional theory （DFT） calculations predict that the first 2 to 3 water layers adjacent to the graphene hole-dope the graphene by several percent of a unit charge per unit cell.

关键词： graphene,non-contact atomic forcemicroscopy (NC-AFM,KPFM),liquid-solid interfacestructure,electronic transport innanoscale materials andstructuresgraphene,non-contact atomic forcemicroscopy (NC-AFM,KPFM),liquid-solid interfacestructure,electronic transport innanoscale materials andstructures