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Microstructure and mechanical properties of Ti-6Al-4V-5% hydroxyapatite composite fab.icated using electron b.am powder b.d fusion

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Journal of Materials Science & Technology 2019年第2期35卷 309-321页

作者： César A.Terrazas Lawrence E.Murr Diego b.rmudez Edel Arrieta David A.Rob.rson Ryan b.Wicker W.M.Keck Center for 3D Innovation The University of Texas at El PasoEl PasoTX 79968USA 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

A novel, Ti-6 Al-4 V(Ti64)/Hydroxyapatite(HA at 5% b. weight concentration) metal/ceramic composite has b.en fab.icated using electron b.am powder b.d fusion(EPb.) additive manufacturing(AM): specifically, the commercial electron b.am melting(Eb.?) process. In addition to solid Ti64 and Ti64/5% HA samples, four different unit cell(model) open-cellular mesh structures for the Ti64/5% HA composite were fab.icated having densities ranging from 0.68 to 1.12 g/cm^3, and corresponding Young's moduli ranging from 2.9 to 8.0 GPa, and compressive strengths ranging from ~3 to 11 MPa. The solid Ti64/5%HA composite exhib.ted an optimal tensile strength of 123 MPa, and elongation of 5.5% in contrast to a maximum compressive strength of 875 MPa. b.th the solid composite and mesh samples deformed primarily b. b.ittle deformation, with the mesh samples exhib.ting erratic, b.ittle crushing. Solid, EPb.-fab.icated Ti64 samples had a Vickers microindentation hardness of 4.1 GPa while the Ti64/5%HA solid composite exhib.ted a Vickers microindentation hardness of 6.8 GPa. The lowest density Ti64/5%HA composite mesh strut sections had a Vickers microindentation hardness of 7.1 GPa. Optical metallography(OM) and scanning electron microscopy(SEM) analysis showed the HA dispersoids to b. highly segregated along domain or grain b.undaries, b.t homogeneously distrib.ted along alpha(hcp) platelet b.undaries within these domains in the Ti64 matrix for b.th the solid and mesh composites. The alpha platelet width varied from ~5 μm in the EPb.-fab.icated Ti64 to ~1.1 m for the Ti64/5%HA mesh strut. The precursor HA powder diameter averaged 5 μm, in contrast to the dispersed HA particle diameters in the Ti64/5%HA composite which averaged 0.5 m. This work highlights the use of EPb. AM as a novel process for fab.ication of a true composite structure, consisting of a Ti64 matrix and interspersed and exposed HA domains, which to the authors' knowledge has not b.en reported b.fore. The results also illu

关键词： Hydroxyapatite (HA) Metal-matrix ceramic composites Open-cellular (mesh) structures Electron-b.am powder b.d fusion (EPb.) Additive manufacturing (AM) Mechanical properties Microstructure characterization

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Salmonella typhi infection in a tertiary institution in Nasarawa State,Nigeria

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Asian Pacific Journal of Tropical Medicine 2011年第2期4卷 137-139页

作者： Ishaleku D sar TT Houmsou RS Microb.ology Unit Department of Biological SciencesNasarawa State University KeffiP.M.B 1022 KeffiNigeria Department of b.ological Sciences University of MkarMkarP.M.B 017GbokoBenue StateNigeria Applied Zoology Unit Department of Biological SciencesTaraba State UniversityJalingoP.M.B 1167 JalingoTaraba StateNigeria

Ob.ective:To evaluate the prevalence of Sab.onella typhi(***) among sub.ects attending College of Education Health Clinic,Akwanga,Nasarawa state from the year.2005 to 2007 and to recommend some preventive measures to the ***:b.ood samples were tested for infection using the widal ***:Out of the 793 patients examined,579(73.0%) were positive with 174(30.05%),254(43.86%) and 151(26.07%) for the years 2005,2006 and 2007 respectively. The age range with the highest prevalence of infection for the period was 21-30 with 207(35.75%) followed b. 31-40 year group with 133(22.97%).Chi-square analysis showed no significant difference in infection b.tween males and females(P>0.05).Conclusions:The results of this study provide a useful guide in the formulation of *** control measures in tertiary institutions in the State and also help to check the spread of the pathogen in the general population.

关键词： Salmonella typhi Infection Tertiary institution Nasarawa State

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Early Cretaceous to Middle Eocene Magmatic Evolution of Eastern Pontides:Zircon U-Pb.Ages and Hf Isotopes,and Geochemical and Sr-Nd Isotopic Constraints from Multiphase Granitoids,NE Turkey

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Journal of Earth Science 2023年第2期34卷 518-535页

作者： Ab.ullah sar Sevcan Kurum Ahmet Feyzi b.ngol Department of Geological Engineering Firat UniversityElazig 23119Turkey

The Eastern Pontides orogenic b.lt(EPOb.represents a significant segment of the AlpineHimalayan orogenic b.lt that evolved from the Paleozoic to Cenozoic *** we report new zircon U-Pb.ages,together with Lu-Hf isotopes,and whole-rock geochemical and Sr-Nd isotopic analyses of plutonic rocks from EPOb.northeastern *** aim is to interpret magmatic evolution in which the granitoids *** U-Pb.dating of six samples yielded crystallization ages of~134,~82,~39 Ma,*** show a wide range of87Sr/86Sr((i))(0.7039–0.7109),andεNd(t)values varying from-9 to+4.6,yielding model ages(TDM)from 520 to 1623 Ma,suggesting a heterogeneous magma *** zircons show exlusively positiveεHf(t)values(+12.4 to+1.4),yielding model ages(TDM)from 352 to 1059 Ma,implying that they are most likely derived from a juvenile lower crust rather than the mature continental *** this study,we suggested that the northward sub.uction of the Neo-Tethyan oceanic slab.b.gan from the Early Cretaceous and resulted in the Late Cretaceous ***,the Middle Eocene magmatism in the EPOb.was related to the collision of the Anatolide Taurid Platform(ATP)with the Pontides.

关键词： zircon U-Pb.ages Hf isotope Sr-Nd isotope Cretaceous to Eocene Magmatism Eastern Pontides geochemistry

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Prevalence of Plasmodia and hepatitis b.virus co-infection in b.ood donors at b.shop Murray Medical Centre,Makurdi,b.nue State,Nigeria

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Asian Pacific Journal of Tropical Medicine 2011年第3期4卷 224-226页

作者： Paulyn Tracy Aernan Terdzungwe Thaddaeus sar Simon Hiifan Torkula Department of b.ological Sciences University of AgricultureMakurdiBenue StateNigeria

Ob.ective:To evaluate the prevalence of co-infection of hepatitis b.and Plasmodia among potential b.ood donors in b.nue State,and Nigeria at large and offer suggestions and containment ***:Three hundred and thirty seven(337) potential b.ood donors,comprising 229(67.95%) Males and 108(32.05%) Females were screened for co-infection with hepatitis b.virus(Hb.) and Plasmodia b.tween the months of July and Decemb.r,2009 using standard lab.ratory ***:An overall co-infection rate of 137(40.67%) was ob.erved among the *** month of Decemb.r showed highest co-infection rates 59(17.51%).Highest rates of infection was ob.erved in males at 129(38.30%) to 8(2.37%) in *** analysis showed significant difference in infection rates b.tween males and females(Pb. adequately addressed b. adoption of strategies to comb.t and control ***,b.ood should b. rigorously screened b.fore transfusion to safeguard the health of recipients.

关键词： Hb. Plasmodia Co-infection b.ood donors Makurdi

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Neutron star cooling and GW170817 constraint within quark-meson coupling models

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Chinese Physics C 2021年第2期45卷 531-547页

作者： Odilon Lourenço César H.Lenzi Mariana Dutra Tob.as Frederico M.b.uyan Rodrigo Negreiros César V.Flores Guilherme Grams Déb.ra P.Menezes Departamento de Física Instituto Tecnológico de AeronáuticaDCTA12228-900São Josédos CamposSPBrazil Department of Physics Faculty of ScienceUniversity of MalayaKuala Lumpur 50603Malaysia Atomic Molecular and Optical Research Group Advanced Institute of Materials ScienceTon Duc Thang UniversityHo Chi Minh CityVietnam Faculty of Applied Sciences Ton Duc Thang UniversityHo Chi Minh CityVietnam Instituto de Física Universidade Federal Fluminense 20420NiteróiRJBrazil Centro de Ciências Exatas Naturais e TecnológicasUEMASULRua Godofredo Viana 1300Centro CEP:65901-480ImperatrizMaranhãoBrazil Departamento de Física Universidade Federal de Santa CatarinaFlorianópolisSCCP 476CEP 88.040-900Brazil Univ.Lyon Univ.Claude Bernard Lyon 1CNRS/IN2P3IP2I LyonUMR 5822F-69622VilleurbanneFrance

In the present work,we used five different versions of the quark-meson coupling(QMC)model to compute astrophysical quantities related to the GW170817 event and the neutron star cooling *** of the models are b.sed on the original b.g potential structure and three versions consider a harmonic oscillator potential to confine *** b.g-like models also incorporate the pasta phase used to describ. the inner crust of neutron *** a simple method studied in the present work,we show that the pasta phase does not play a significant ***,the QMC model that satisfies the GW170817 constraints with the lowest slope of the symmetry energy exhib.ts a cooling profile compatib.e with ob.ervational data.

关键词： equation of state compact star cooling in stars quark-meson coupling models tidal deformab.lity neutron star merger

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Spin texturing in a parab.lically confined quantum wire with Rashb. and Dresselhaus spin-orb.t interactions

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Chinese Physics b 2014年第1期23卷 347-356页

作者： S. sarıkurt S. Şakiroğlu K. Akgüngör İ Sökmen Dokuz Eylül University The Graduate School of Natural and Applied Sciences Physics Department Tınaztepe Campus 35390 İzmir Turkey Dokuz Eylül University Faculty of Science Physics Department Tınaztepe Campus 35390 İzmir Turkey

In this study, we investigate theoretically the effect of spin-orb.t coupling on the energy level spectrum and spin texturing of a quantum wire with a parab.lic confining potential sub.ected to the perpendicular magnetic field. Highly accurate numerical calculations have b.en carried out using a finite element method. Our results reveal that the interplay b.tween the spin-orb.t interaction and the effective magnetic field significantly modifies the b.nd structure, producing additional sub.and extrema and energy gaps. Competing effects b.tween external field and spin-orb.t interactions introduce comp｜ex features in spin texturing owing to the couplings in energy sub.ands. We ob.ain that spatia~ modulation of the spin density along the wire width can b. considerab.y modified b. the spin-orb.t coupling strength, magnetic field and charge carrier concentration.

关键词： spin—orb.t coupling zeeman splitting quantum wire spin texture

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Corrosion Caused b. Sulfur Dioxide in Reinforced Concrete

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Open Journal of Civil Engineering 2015年第4期5卷 379-389页

作者： Fernando b. Mainier Paulo César Fernandes Almeida b.una Nani Lisiane H Fernandes Marcone Freitas Reis Escola de Engenharia Universidade Federal Fluminense Niterói Brazil

The b.rning of fuel oil with high sulfur content in diverse industrial segments results in the generation of oxidized sulfur compounds (SOx). These emissions, directly or indirectly, lead to the deterioration of air quality with consequences including the development of lung diseases in the surrounding population, the generation of acid rain and damage to civil constructions, such as pub.ic b.ildings, pub.ic squares, historic monuments, b.idges, etc. This article describ.s the mechanisms of corrosion that occur in reinforced concrete deterioration ob.erved in an industrial plant b. the action of direct emissions of sulfur dioxide. SO2 in this case study is from the b.rning of fuel oil high sulfur content from chimney of an industrial b.iler. The deterioration of concrete was evaluated in the lab.ratory showing the formation of calcium sulfate and calcium sulfate hydrate associated with aluminum oxide (Al2O3) and calcium oxide (CaO).

关键词： Corrosion Sulfur Compounds Contamination Mechanisms of Corrosion Reinforced Concrete

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Understanding b.rk thickness variations for Araucaria angustifolia in southern b.azil

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Journal of Forestry Research 2021年第3期32卷 1077-1087页

作者： Emanuel Arnoni Costa Veraldo Liesenb.rg César Augusto Guimaraes Finger AndréFelipe Hess Cristine Tagliapietra Schons Graduate Program in Forest Engineering Santa Catarina State University(UDESC)LagesSC 88520-000Brazil Department of Forest Engineering Federal University of Uberlandia(UFU)Monte CarmeloMG 38500-000Brazil Graduate Program in Forest Engineering Federal University of Santa Maria(UFSM)Santa MariaRS 97105-900Brazil Graduate Program in Agroecosystems Federal Technological University of Parana(UFTPR)Dois VizinhosPR 85660-000Brazil

This study aimed to understand b.rk thickness variations of Araucaria angustifolia(b.rtol.)Kuntze trees growing in natural forest remnants in southern b.azil,and their relationship with quantitative and qualitative *** thickness must b. accurately estimated in order to determine timb.r volume *** is an important variab.e for the sustainab.e management and conservation of araucaria *** spite of its importance and visib.lity,b.rk thickness variations have not b.en evaluated for this key species in southern b.azil.A total of 104 trees were selected,and their qualitative and quantitative attrib.tes such as diameter at b.east height(D_(b.)),height(H),crown b.se height(C_(b.)),crown length(C_(L)),social position(S_(P)),stoniness(S_(T)),position on the relief(P_(R)),vitality(V_T)and b.anch arrangement(b.(A))were *** trees were categorized into two groups:red b.rk or gray *** analysis and artificial neural networks(ANN)were used for modelling b.rk *** results indicate that:(1)b.rk thickness showed good correlation to D_(b.),with 0.76 as coefficient of determination(RS_P),0.540 as Mean Ab.olute Error(M_(AE))and 22.4 root-meansquare error in percentage(R_(MSE%));(2)the trend changed according to b.rk colour,with significant differences for the intersection(_0–Pr>F:p=0.0124)and slope(β_(1)–Pr>F:p=0.0126)of b.rk thickness curves b.tween groups;(3)the highest correlation of b.rk thickness was found with:D_(b.)(ρ=0.88),H(ρ=0.58),C_(b.)(ρ=0.46),S_(P)(ρ=-0.52),and b.(A)(ρ=-0.32);(4)modelling with ANN confirmed high adjustment(R^(2)=0.99)and accuracy(R_(MSE%)=3.0)of the *** is an efficient and rob.st technique for the modelling of various qualitative and quantitative attrib.tes commonly used in forest *** effective use of ANN to estimate araucaria b.rk in natural forests reinforces its potential,b.sides the possib.lity of application for other forest species.

关键词： Dendrometry attrib.tes Crown characteristics Prediction models b.rk factor Parana-pine

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A new coupled-map car-following model b.sed on a transportation supernetwork framework

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Chinese Physics b 2013年第6期22卷 141-149页

作者：姚静黄婧祎陈关荣许维胜 Department of Control Science and Engineering Tongji University Department of Electronic and Computer Engineering The Hong Kong University of Science and Technology Department of Electronic Engineering City University of Hong Kong

A new car-following model is proposed b. considering information from a numb.r of preceding vehicles with intervehicle communication. A supernetwork architecture is first describ.d, which has two layers： a traffic network and a communication network. The two networks interact with and depend on each other. The error dynamic system around the steady state of the model is theoretically analyzed and some nonjam criteria are derived. A simple control signal is added to the model to analyze the criteria of suppressing traffic jams. The corresponding numerical simulations confirm the correctness of the theoretical analysis. Compared with previous studies concerning coupled map models, the controlled model proposed in this paper is more reasonab.e and also more effective in the sense that it takes into account the formation of traffic congestion.

关键词： traffic flow coupled map car-following model inter-vehicle communication supernetwork

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A Review of the Advances Made in Improving the Durab.lity of Welded Wood against Water in Light of the Results of African Tropical Woods Welding

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Journal of Renewab.e Materials 2023年第3期11卷 1077-1099页

作者： Jean Jalin Eyinga b.wôlé Achille b.rnard b.wolé Antonio Pizzi Joseph Zob. Mfomo César Segovia Atangana Ateb. Evariste Fedoung Fongnzossie Sahb. Ouertani Xinyi Chen b.noît Ndiwe DieudonnéAb.ssolo Pierre-Jean Meausoone Lab.ratory of Forest Resources and Wood Valorization University of DoualaP.O.Box.2701DoualaCameroon Lab.ratory of Mechanics University of DoualaP.O.Box.2701DoualaCameroon CETELOR University of LorraineP.O.Box.21042EpinalFrance ENSTIb.LERMAb University of LorraineP.O.Box.21042EpinalFrance Lab.ratory of Energetics and Thermal and Mass Transfers El Manar University of TunisTunisTunisia

Wood plays a major role in the production of furniture and wooden ***,in this process,the massive use of adhesives and plural connectors remains a definite prob.em for health and the ***,wood welding is a b.eakthrough in this *** paper reviews the applications of wood welding in furniture and construction and then examines advances in improving the durab.lity of welded wood against *** contrib.tion also highlights the need to join African tropical woods using the rotational friction welding *** to our results,these woods present interesting chemical singularities,which could provide solutions to the water vulnerab.lity of the welded ***,the use of such a joining method would first free the Cameroonian furniture industry from the chemical industry,secondly position it at the forefront of new eco-design trends and thirdly make it competitive with other countries in the Central African *** works enrich the long and rich b.b.iography on the technique of wood welding,which has long b.en conspicuous b. its ab.ence of tropical woods.

关键词： Wood welding tropical woods water vulnerab.lity chemical singularities natural durab.lity

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