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electric,magnetic and microstructural features of the La_(2)CofeO_(6) lanthanide ferrocobaltite obtained by the modified Pechini route

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Journal of Advanced Dielectrics 2021年第3期11卷 16-25页

作者： J.A.Jaramillo Palacio K.A.Munoz Pulido J.Arbey Rodríguez D.A.Landínez Téllez J.Roa-Rojas Grupo de física de Nuevos Materiales Departamento de Física Universidad Nacional de ColombiaBogotáDCColombia laboratório de magnetismo e materiais magnéticos departamento de física Universidade Federal de Santa Maria Rio Grande do Sul Brazil Grupo de estudios de Materiales Departamento de Física Universidad Nacional de ColombiaBogotáDCColombia

In the search for new materials with applicable magnetic properties in spintronic devices,the aim of this work is to report the synthesis of the lanthanide ferrocobaltite La_(2)CofeO_(6) using the modified Pechini route;the experimental study of structural,morphological and magnetic properties,and the analysis of the electronic structure and bands are obtained in the framework of the density functional *** refinement of experimental X-ray diffraction patterns revealed the crystallization of this oxide material in a perovskite-like monoclinic structure,space group P2_(1)/n(#14).Scanning electron microscopy and atomic force microscopy images revealed that the surface morphology is essentially polycrystalline,with mean grain sizes between 177 and 188 *** dispersive X-ray spectroscopy suggests that the material obtained contains La,fe,Co and O in the stoichiometric proportions expected by up to 98%.The magnetic susceptibility curves as a function of temperature indicated that the material is ordered ferromagnetically,showing strong irreversibility effects due to the disorder of the fe and Co cations in the three crystallographic directions of the structure and to the strong distortions in the feO_(6) and CoO_(6) *** hysteresis curves confirmed the ferromagnetic character of the material for all temperatures evaluated,up to room temperature.I-V response curves revealed a semiconductor-like behavior with a figure of merit exponent 1.53 of the varistor *** ferromagnetic semiconductor behavior suggests the potential applicability of the material in spintronic technological devices.

关键词： Double perovskite Pechini method crystalline structure ferromagnetic response semiconductor behavior

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The role of physical properties in explosive welding of copper to stainless steel

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defence Technology（防务技术） 2023年第4期22卷 88-98页

作者： G.H.S.f.L.Carvalho I.Galvao R.Mendes R.M.Leal A.B.Moreira A.Loureiro Univ Coimbra CEMMPREDepartamento de Engenharia Mec^anicaRua Luís Reis Santos3030-788CoimbraPortugal department of Industrial engineering University of FirenzeVia di Santa Marta 350139FirenzeItaly ISeL Departamento de Engenharia Mec^anicaInstituto Politecnico de LisboaRua Conselheiro Emídio Navarro 11959-007LisboaPortugal Univ Coimbra ADAILEDAPDepartamento de Engenharia Mec^anicaRua Luís Reis Santos3030-788CoimbraPortugal LIDA-eSAD.CR Instituto Politecnico de LeiriaRua Isidoro Inacio Alves de Carvalho2500-321Caldas da RainhaPortugal Univ.Porto LAETA/INEGIDept.Eng.Metalúrgica e de MateriaisR.Dr.Roberto Frias4200-465PortoPortugal

This paper investigates the effects of the physical properties on the microstructure and weldability of explosive welding by joining two metals with a significant contrast in thermophysical properties:stainless steel and *** welds between stainless steel and copper were obtained,and the interfacial morphology was wavy,regardless of the position of the *** weldability of dissimilar pairs was found to be more dependent on the relationship between the physical properties of the base materials than on the absolute value of the material *** there is a significant difference in thermal conductivity between the flyer and the base plate,together with a material with a low melting temperature,the weldability of the pair is often *** relative position of the plates affects the interfacial microstructure even when similar morphologies are *** the metallic pairs studied,the wave size was bigger for the configuration in which the ratio between the density of the flyer and the density of the base plate is *** same phenomenon was observed for the impedance:bigger waves were found for a smaller ratio between the impedance of the flyer and the impedance of the base plate.

关键词： explosive welding Solid-state Copper-stainless steel Dissimilar Interface morphology Weldability

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Modeling the crystallographic structure of Ho(Ni,Co,Mn)O_(3±δ) perovskite-type manganite

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Journal of Advanced Ceramics 2012年第4期1卷 274-282页

作者： C.Morilla-Santos f.f.ferreira W.H.Schreiner O.Peña P.N.Lisboa-filho UNeSP-Univ estadual Paulista POSMAT-Programa de Pós-Graduação em Ciência e Tecnologia de MateriaisBauruBrazil UfABC-Universidade federal do ABC-Centro de Ciências Naturais e Humanas Santo AndréBrazil UfPR-Universidade federal do Paraná Departamento de FísicaCuritibaBrazil Sciences Chimies de Rennes UMR 6226 Universitéde Rennes 1RennesFrance UNeSP-Univ estadual Paulista Faculdade de CiênciasDepartamento de FísicaBauruBrazil

Crystallographic and microstructural properties of Ho(Ni,Co,Mn)O3±dperovskite-type multiferroic material are *** were synthesized with a modified polymeric precursor *** synchrotron X-ray powder diffraction(SXRPD)technique associated to Rietveld refinement method was used to perform structural *** crystallographic structures,as well as microstructural properties,were studied to determine unit cell parameters and volume,angles and atomic positions,crystallite size and strain.X-ray energies below the absorption edges of the transition metals helped to determine the mean preferred atomic occupancy for the substituent ***,analyzing the degree of distortion of the polyhedra centered at the transitions metal atoms led to understanding the structural model of the synthesized phase.X-ray photoelectron spectroscopy(XPS)was performed to evaluate the valence states of the elements,and the tolerance factor and oxygen *** obtained results indicated a small decrease distortion in structure,close to the HoMnO3 basis *** addition,the substituent atoms showed the same distribution and,on average,preferentially occupied the center of the unit cell.

关键词： crystallographic structure X-ray powder diffraction Rietveld refinement manganites

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Structural metamaterials with negative mechanical/thermomechanical indices: A review

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Progress in Natural Science:Materials International 2021年第6期31卷 801-808页

作者： Jo?o O.Cardoso Jo?o Paulo Borges Alexandre Velhinho CeNIMAT/i3N Departamento de Ciência dos Materiais Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa

Structural metamaterials presenting negative values of one or more mechanical and thermomechanical indices–namely the Poisson's ratio, the linear compressibility, and the coefficient of thermal expansion – are the promising candidates to the applications in many fields, ranging from precision mechanics to biomedical devices or energy absorption. Although scattered mentions may be found in the literature since the late eighties of 20th century, the systematic research efforts concerning these materials became effective much later. The present work is to review the main scientific contributions to the topic in the last five years. This paper first deals with those metamaterials showing a single negative index, and then proceeds to analyze the much less frequent instances of coupled negative indices, with emphasis on the so-called anepectic case, which exhibits an unusual thermomechanical response.

关键词： Mechanical and thermomechanical metamaterials Auxetic Anepectic Negative Poisson's ratio Negative thermal expansion Negative linear compressibility

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Influence of Microstructures on Polarization Resistance and Hydrogen-Induced Cracking of a Micro-Alloyed Steel Submitted to Different Cooling Rates

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Journal of Iron and Steel Research(International) 2011年第S1期18卷 168-172页

作者： González M R Martins de Araújo D S Goldenstein H Alonso-falleiros N departamento de engenharia Metalúrgica e de materiais EscolaPolitécnicaUniversidade de Sao Paulo-SP-Brasil

The effect of different microstructures on the polarization resistance (Rp) and the hydrogen-induced cracking (HIC) of a micro-alloyed steel austenitized and submitted to different cooling rates was *** 19.1 x 6 x 2 mm,containing the whole thickness of the plate were extracted from a 20 mm plate and heat treated on a quenching dilatometer,were submitted to Rp and HIC corrosion *** Rp and HIC tests followed as close as possible ASTM G59 and NACe standard TM0284-2003,in this case,modified only with regard to the size of the *** samples transformed from austenite by a slow cooling (cooling rate of 0.5℃.s-1) showed higher susceptibility to hydrogen-induced cracking,with large cracks in the middle of the sample propagating along segregation bands,corresponding to the centerline of the plate *** cooling rates of 10℃.s-1,only small cracks were found in the matrix and micro cracks nucleated at non-metallic *** higher cooling rates (40℃.s-1) very few small cracks were detected,linked to non-metallic *** result suggests that structures formed by polygonal structures and segregation bands (were eutectoid microconstituents predominate) have higher susceptibility to *** predominantly formed by acicular ferrite make it difficult to propagate the cracks among non-oriented and interlaced acicular ferrite *** segregation bands containing eutectoid products also help inhibit cracking and crack propagation;segregation bands can function as pipelines for hydrogen diffusion and offer a path of stress concentration for the propagation of cracks,frequently associated to non-metallic *** resistance essays performed on the steel in theas received condition,prior to any heat treatment,showed larger differences between the regions of the plate,with a considerably lower Rp in the *** austenitization heat treatments followed by cooling rates of 0.5 e 10℃.s-1 made more uniform the

关键词： hydrogen induced cracking polarization resistance micro-alloyed steel control cooling

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Recent advances in magnetic electrospun nanofibers for cancer theranostics application

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Progress in Natural Science:Materials International 2021年第6期31卷 835-844页

作者： Paula I.P.Soares Jo?o Paulo Borges CeNIMAT/i3N Departamento de Ciência dos Materiais Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa

Cancer theranostics is a recent concept that aims to combine in the same device diagnostic and therapeutic features. magnetic nanoparticles(m NPs) are commonly used as a critical part of these systems due to their ability to respond to an external magnetic field. Consequently, m NPs can generate heat when an alternating magnetic field is applied and enhance image contrast in magnetic resonance. However, direct administration of m NPs intravenously or directly in the tumor can lead to undesired side effects because of m NP elimination by macrophages or leakage to healthy tissues. Therefore, m NPs can be retained in a polymeric nanofibrous mesh, thus preventing misplacing or loss of m NPs. furthermore, these magnetic nanofibers can be directly implanted in the tumor site, thus ensuring high m NPs loading and higher magnetic response. In addition, polymeric nanofibers produced by electrospinning are frequently used to maintain a sustained drug release in the tumor site. Therefore,a magnetic polymeric nanofiber produced by electrospinning is an ideal nanosystem for cancer theranostics application. This review summarizes the most recent developments of magnetic nanofibers produced by electrospinning for cancer theranostics applications.

关键词： electrospinning Nanofibers Iron oxide nanoparticles magnetic fluid hyperthermia Cancer theranostics

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Poly(Butylene Adipate-Co-Terephthalate)and Poly(ε-Caprolactone)and Their Bionanocomposites with Cellulose Nanocrystals:Thermo-Mechanical Properties and Cell Viability Study

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Journal of Renewable Materials 2019年第3期7卷 269-277页

作者： Marcia Cristina Branciforti Caroline faria Bellani Carolina Lipparelli Morelli Alice ferrand Nadia Benkirane-Jessel Rosario elida Suman Bretas departamento de engenharia de materiais Universidade de Sao PauloSao CarlosSPBrasil departamento de engenharia de materiais Universidade Federal de Sao CarlosSao CarlosSPBrasil Institut National de la Santéet de la Recherche Médicale Universitéde StrasbourgStrasbourgFrance

Although nanocomposites have recently attracted special interest in the tissue engineering area,due to their potential to reinforce scaffolds for hard tissues applications,a number of variables must be set prior to any clinical *** manuscript addresses the evaluation of thermo-mechanical properties and of cell proliferation of cellulose nanocrystals(CNC),poly(butylene adipate-co-terephthalate)(PBAT),poly(ε-caprolactone)(PCL)films and their bionanocomposites with 2 wt% of CNC obtained by casting *** nanocrystals extracted from Balsa wood by acid hydrolysis were used as a reinforcing phase in PBAT and PCL matrix *** films and pure CNC at different concentrations were cultured with osteoblasts MG-63 and the cell proliferation was assessed by AlamarBlue?*** thermal-mechanical properties of the films were evaluated by dynamic-mechanical thermal analysis(DMTA).It was found by DMTA that the CNC acted as reinforcing *** addition of CNCs in the PBAT and PCL matrices induced higher storage moduli due to the reinforcement effects of *** cell viability results showed that neat CNC favored osteoblast proliferation and both PBAT and PCL films incorporated with CNC were biocompatible and supported cell proliferation along *** nature of the polymeric matrix or the presence of CNC practically did not affect the cell proliferation,confirming they have no in vitro *** features make cellulose nanocrystals a suitable candidate for the reinforcement of biodegradable scaffolds for tissue engineering and biomedical applications.

关键词： Cell viability thermo-mechanical properties cellulose nanocrystals(CNC) biocompatible polymers tissue engineering bionanocomposites

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Structural,microstructural and dielectric characterizations of(Bi_(0.5)Na_(0.5))TiO_(3) based lead-free ferroelectric ceramics

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Journal of Advanced Dielectrics 2021年第3期11卷 39-44页

作者： B.R.Moya A.C.Silva A.Peláiz-Barranco J.D.S.Guerra Grupo de ferroelétricos e materiais Multifuncionais Instituto de física Universidade Federal de Uberlandia UberlandiaMinas Gerais 38408-100Brazil departamento de física e Química UNESP Campus de Ilha SolteiraSao Paulo 15385-000Brazil Grupo de Materiales ferroicos facultad de física-Instituto de Ciencia y Tecnología de Materiales Universidad de La Habana La Habana 10400Cuba

(1-x)(Bi_(0.5)Na_(0.5))TiO_(3)-xBaTiO_(3) lead-free ceramics have been obtained from the conventional solid-state reaction sintering *** structural properties were investigated from X-ray diffraction and Raman spectroscopy *** revealed well-crystallized ceramic samples with perovskite *** properties,obtained from scanning electron microscopy measurements,have shown high density with very low porosity *** dielectric response,analyzed as a function of the temperature and several frequencies,showed very broad peaks with a strong frequency dependence of the temperature for the maximum dielectric permittivity for the modified *** were analyzed considering the influence of the BaTiO3 content on the studied physical properties.

关键词： Lead-free BNT Raman spectroscopy dielectric response

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Gold Supported on Metal Oxides for Carbon Monoxide Oxidation

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Nano Research 2011年第2期4卷 180-193页

作者： Sonia A. C. Carabineiro Nina Bogdanchikova Miguel Avalos-Borja Alexey Pestryakov Pedro B. Tavares Jose L. figueiredo laboratário de Catálise e materiais Associate Laboratory LSRE/LCM Departamento de Engenharia Química Faculdade de Engenharia Universidade do Porto 4200-465 Porto Portugal Universidad Nacional Autónoma de México Centro de Nanociencias y Nanotecnologia Carretera Tijuana-Ensenada 22800 Ensenada Baja California México Tomsk Polytechnic University 30 Lenin Avenue Tomsk 634050 Russia Universidade de Trás-os-Montes e Alto Douro Centro de Quimica-Vila Real Departamento de Química 5001-911 Vila Real Portugal

Au 被装载了(1% wt ) 在不同广告上，氧化物支持(CuO， La2O3， Y2O3， NiO ) 由三个不同方法：两倍受精(暗淡) ，液体阶段减少的免职(LPRD ) ，和 ultrasonication (美国) 。样品被 N2 吸附描述在 ? 196 ??  ??????  ??  ? 洠... 详细信息

Au 被装载了(1% wt ) 在不同广告上，氧化物支持(CuO， La2O3， Y2O3， NiO ) 由三个不同方法：两倍受精(暗淡) ，液体阶段减少的免职(LPRD ) ，和 ultrasonication (美国) 。样品被 N2 吸附描述在 ? 196 ??  ??????  ??  ? 洠浡業汬牡 ?  ???? 猠'T 業牣吗？

关键词：金属氧化物一氧化碳氧化黄金 Au纳米粒子 X射线荧光光谱仪透射电子显微镜选区电子衍射程序升温还原

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Periodic Modulation of Nonlinearity in a Two-Core Photonic Crystal fiber: A Numerical Investigation

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Journal of electromagnetic Analysis and Applications 2015年第2期7卷 41-51页

作者： A. f. G. f. filho A. G. L. S. O. Mendes J. R. R. Sousa G. S. Batista A. M. Bastos C. S. Sobrinho M. L. Lyra A. S. B. Sombra laboratório de Telecomunicacoes e Ciência e engenharia de materiais LOCeM Departamento de Física Universidade Federal do Ceará Ceará Brazil departamento de engenharia de Teleinformática (deTI) Centro de Tecnologia Universidade Federal do Ceará Ceará Brazil Instituto de física Universidade Federal de Alagoas Maceió Brazil

We present a numerical investigation of the propagation and the switching of ultra-short pulses (100 fs) in a two-core nonlinear coupler of photonic crystal fibers constructed with periodically modulated the non-linearity fiber (PMNL-PfC). Our simulations are taking into account different amplitude and frequency modulations of the PMNL-PfC. A coupler for coupling whose length is Lc = 1.8 cm, the transmission characteristics, the compression factor, the crosstalk (Xtalk) and extinction ratio (Xratio) levels of the first order solitons were studied for low to high pump energies considering 2Lc. By an analysis on the reference channel (channel 2), it is observed that at low modulation frequencies an increase occurs in the switching power increasing transmission efficiency. for high modulation frequencies, the transmitted energy efficiency loses. The switching pulses are stronger for low frequency and high amplitude modulation. The Xtalk is a function of the measurement made on the secondary channel (channel 1). It was observed that this unwanted high-frequency energy increases to lessen the measure of the amplitude modulation. In summary, we have demonstrated that introduction of a non-linearity profile takes the periodically modulated PMNL-PfC to strong variations at transmission efficiency, Xtalk, Xratio a function of frequency and modulation amplitude and the input power.

关键词： Coupler of Photonic Crystal fibers Periodically Modulated the Non-Linearity Two-Core Nonlinear Crosstalk Level extinction Ratio Level

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