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13th Pure and Applied Chemistry International Conference, PACCON 2019

作者： Wongpreedee, Thapanee Mougin, Karine Amornsakchai, Taweechai Program in Materials Science and Engineering Faculty of Science Mahidol University SalayaNakhon Pathom73170 Thailand Institut de Science des Materiaux de Mulhouse IS2M-CNRS-UHA 15 Rue Jean Starcky B.P.2488-68057 Mulhouse Cedex France Department of Chemistry and Center of Excellence for Innovation in Chemistry Faculty of Science Mahidol University Phuttamonthon 4 Road SalayaNakhon Pathom73170 Thailand Center of Sustainable Energy and Green Materials Faculty of Science Mahidol University Phuttamonthon 4 Road SalayaNakhon Pathom73170 Thailand

ISBN: (纸本)9783035715521

Pineapple leaf fiber (PALF) having an average diameter and length of about 4 µm and 6 mm, respectively, was used as reinforcing element for natural rubber (NR) composites. PALF was coated with different amount of stearic acid at 10, 30 and 50 wt% of PALF. PALF-NR composites containing two levels of PALF at 5 and 10 part per hundred rubber (phr) were prepared in a two roll mill. Mastication times of 2, 4 and 8 min were used. Tensile stress-strain curves and fracture surfaces of both untreated PALF and stearic acid coated PALF (SA-PALF) reinforced NR prepared with different mastication times were compared. At a low level of PALF where aggregation was not a problem, stearic coating had an adverse effect on the mechanical properties due to the slippery PALF-rubber interface. At a high level of PALF, the coating gave composites with higher tensile strength and strain at break. Moreover, tensile strength and strain at break increased with increasing mastication time. This indicates that stearic acid coating reduces the formation of PALF aggregations and allows PALF to work effectively. © 2019 Trans Tech Publications Ltd, Switzerland.

关键词： Reinforcement

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Influence of Treatment Time on the Synthesis of Copper Oxide Films by Cathode Cage Plasma Deposition

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SSRN 2023年

作者： de Carvalho, Júlio F.S. Monção, Renan M. de Sousa, Ediones M. da Luz Lima, Cleânio Costa, Carla L.S.C. Garcia, Ramón R.P. Feitor, Michelle C. de Carvalho Costa, Thércio H. Libório, Maxwell S. de Sousa, Rômulo R.M. Federal University of Piauí Graduate Program in Materials Science and Engineering PI Teresina Brazil Federal University of Piauí Physics Postgraduate Program PI Teresina Brazil Federal university of Rio Grande do Norte Department of Materials Science and Engineering RN Natal Brazil Federal University of Rio Grande do Norte Department of Mechanical Engineering RN Natal Brazil Federal university of Rio Grande do Norte School of Science and Technology RN Natal Brazil

Copper oxide is a valuable p-type semiconductor for photovoltaic applications. In this work, plasma deposition with cathodic cage (CCPD) of copper oxide (CuO+Cu2O) films on glass was performed to evaluate the microstructural, morphological, chemical, and bandgap changes as a function of the treatment time variation (2, 3, 4, and 5 hours). The samples were analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive System (EDS), X-ray Diffraction (XRD), and Raman Spectroscopy to identify morphologies, chemical composition, and crystalline phases of the deposited films, and the absorption spectrum optics was used to calculate the bandgap width. All films showed bandgap energies around 2.60 eV. However, the sample treated with a time of 3h presented a compact coating with 1.46 µm of thickness and bandgap energy equal to 2.57 eV, being the best result. © 2023, The Authors. All rights reserved.

关键词： Energy gap

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Microstructural development of porous β-Si3N4 ceramics prepared by pressureless-sintering compositions in the Si-Re-O-N quaternary systems (Re=La, Nd, Sm, Y, Yb)

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31st International Conference on Advanced Ceramics and Composites

作者： Quinlan, Mervin Heard, D. Plucknett, Kevin P. Garrido, Liliana Genova, Luis Materials Engineering Program Department of Process Engineering and Applied Science Dalhousie University 1360 Barrington Street Halifax NS B3J 1Z1 Canada M.B. Gonnet. Pcia De Buenos Aires Argentina IPEN Instituto de Pesquisas Energéticas e Nucleares CCTM Centro de Ciência e Technologia de Materiais Cidade Universitária Travessa R 400 05508-900 São Paulo Brazil

ISBN: (纸本)9780470196403

It has recently been demonstrated that porous β-Si3N 4 can be engineered to provide similar mechanical properties to dense β-Si3N4, with the additional benefits of reduced mass. Porous p-Si3N4 applications could potentially include filtration media, thermal shock resistant components and high-strength, lightweight structural components. Prior work in Japan has shown that flexural strengths exceeding 1 GPa can be achieved by tailoring the microstructure of the β-Si3N4 grains, such that moderately high aspect ratios are obtained after sintering (up to 10:1) with considerable anisotropic grain alignment, while maintaining porosity levels of ∼10-15 %. In the present study, β-Si3N4 ceramics containing higher porosity levels are generated via pressureless sintering in a nitrogen atmosphere, with the addition of single rare earth oxide sintering aids. The oxide additives have been chosen from both the lanthanide (La, Nd, Sm, Yb) and Group IIIb (Y) elements. In each case, the compositions were milled for 24 hours, cold isostatically pressed and then sintered in nitrogen (0.1 MPa) at temperatures ranging from 1500 to 1750°C. Post sinter microstructural characterization was performed using scanning electron microscopy and x-ray diffraction. It is noted that densification and phase transformation kinetics are both strongly influenced by the oxide chosen.

关键词： X ray diffraction

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Antioxidant Effects of Vitamin C on biomedical UHMWPE Compounds

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Macromolecular Symposia 2019年第1期383卷

作者： Souza, Vanessa C. Fim, Fabiana C. Lima, Maria Edvania A. Silva, Lucineide b. Postgraduate Program in Materials Science and Engineering – CT/ UFPB Cidade Universitária s/n João Pessoa/PBCEP: 58051-900 Brazil Cidade Universitária s/n João Pessoa/PBCEP: 58051-900 Brazil

The aim of the present study is to evaluate the antioxidant activity of ascorbic acid (Vitamin C) at concentrations of 0.5, 1.0, and 2.0% wt on biomedical Ultra High Molecular Weight Polyethylene (b-UHMWPE), using a stable free radical 2,2-diphenyl-1-picryl-hydrazyl (DPPH). The compounds are prepared by compression molding at 160 °C for 6 min, and pressure of 10 MPa. Infrared spectroscopy indicated a weak interaction between the compound constituents, at 3600, 1800, and 1500 cm−1 bands attributed to Vitamin C. Atomic force microscopy (AFM) revealed that the addition of 2.0% wt. of Vitamin C promoted b-UHMWPE crystalline particle size decreases and molecular disorder. In the presence of the vitamin, Raman spectroscopy suggested a decrease in the degree of polymer crystallinity which may be attributable to modifications in morphological aspects of the polymer. Vitamin C acted as an antioxidant agent, an important result;an increasing amount of radical is scavenged with the addition of the vitamin to the compounds. Thus, Vitamin C presents potential as an antioxidant for b-UHMWPE compounds. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

关键词： Infrared spectroscopy

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Tecnological Tests of the Pegamites Residues Extraction at Alto Dois Irmãos/Pb in borborema Pegmatitic Province/bpp

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SSRN 2023年

作者： Silva, Gerson Ferreira de brum, Irineu Cordeiro, Vinícius becheleni, Emily Araújo, Defsson Federal University of Rio Grande do Sul – UFRGS Postgraduate Program in Mining Engineering Metallurgical and of Materials Brazil Federal University of Rio Grande do Sul – UFRGS Department of Metallurgical Engineering Postgraduate Program in Mining Engineering Metallurgical and Materials Brazil Federal University of Campina Grande – UFCG Academic Unity of Mining and Geology Brazil Federal University of Vales do Jequitinhonha e Mucuri – UFVJM Engineering Institute Science and Technology Brazil Federal University of Campina Grande – IFPB Federal Institute of Science Education and Technology of Paraíba Campus Picuí Brazil

The borborema Pegmatitic Province – bPP situated between Paraiba and Rio Grande do Norte states in brazilian northeast presents several pegmatites occurrences. In the region of the county of Pedra Lavrada – Pb, are observed various mineral occurrences where the pegmatites have been explored with prominence at Alto Dois Irmãos-Pb pegmatite, in what quartz, feldspar and mica are extracted. because an existence of a complex mineralogy of the pegmatites, the understanding about mineral constituent is fundamental to define its industrial employment and also to implement improvements in beneficiation process. The proposal of this research line is the detailed characterization and proof that part of the ore (quartz) considered sterile, presents low poisoning (Fe2O3) and high silica (SiO2) content, to enable its industrial use mainly to nobler purposes. Also will be fundamental to minimize the environmental impact and decrease the grinding energetic consume. besides that, the obtained results of this research will be used in a future work, as inputs in simulation stage, aiming to optimize the researched beneficiation unity grinding process. To the pegmatite characterization were done density determination tests, mineralogical identification by X-ray diffraction (XRD), chemical analysis by fluorescents X-rays and morphological analysis by scanning electron microscopy (SEM/EDS). Then were done tests to Work Index (WI) calculous. The sterile (quartz extraction) from pegmatite mining in Pedra Lavrada/Pb presented medium density of 2,66g/cm3, majority chemical composition of silicon and oxygen and quartz as the mainly mineralogical stage, through X-ray diffractograms and scanning electron microscopy images, what indicates that this material has high purity. The Work Index (WI) was 15,9 kwh/t, showing that this material presents in the pegmatite can be consider resistant to breaking in grinding process. © 2023, The Authors. All rights reserved.

关键词： Quartz

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Nanocrystalline material in toroidal cores for current transformer: Analytical study and computational simulations

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materials Research 2005年第4期8卷 395-400页

作者： Luciano, benedito Antonio Cavalcante de Albuquerque, João Marcelo benício de Castro, Walman Moreira Afonso, Conrado Ramos Department of Electrical Engineering CEEI/UFCG P.B. 10105 58109 970 Campina Grande - PB Brazil Department of Mechanical Engineering CCT/UFCG P.B. 10105 58109-970 Campina Grande - PB Brazil Department of Materials Engineering Pos-Graduate Program in Materials Science Engineering UFSCar Via Washington Luís km 235 13565-905 São Carlos - SP Brazil

based on electrical and magnetic properties, such as saturation magnetization, initial permeability, and coercivity, in this work are presented some considerations about the possibilities of applications of nanocrystalline alloys in toroidal cores for current transformers. It is discussed how the magnetic characteristics of the core material affect the performance of the current transformer. From the magnetic characterization and the computational simulations, using the finite element method (FEM), it has been verified that, at the typical CT operation value of flux density, the nanocrystalline alloys properties reinforce the hypothesis that the use of these materials in measurement CT cores can reduce the ratio and phase errors and can also improve its accuracy class. © 2005.

关键词： Steel

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Compositional design of porous β-Si3N4 prepared by pressureless-sintering compositions in the Si-Y-Mg-(Ca)-O-N system

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31st International Conference on Advanced Ceramics and Composites

作者： Quinlan, Mervin Plucknett, Kevin P. Garrido, Liliana Genova, Luis Materials Engineering Program Department of Process Engineering and Applied Science Dalhousie University 1360 Barrington Street Halifax NS B3J 1Z1 Canada M.B. Gonnet. Peia. De Buenos Aires Argentina IPEN Instituto de Pesquisas Energéticas e Nucleares CCTM Centro de Ciência e Technologia de Materiais Cidade Universitária Travessa R 400 05508-900 São Paulo Brazil

ISBN: (纸本)9780470196403

Porous β-Si3N4 can be microstructurally engineered to provide similar mechanical properties to dense β-Si 3N4 with the additional benefits of reduced mass. However, while flexural strengths exceeding 1 GPa can be achieved by tailoring the microstructure of the material, through alignment of anisotropic β-Si 3N4 grains, the porosity levels of such materials are still relatively low (3N4 structure (ideally 20-40 vol. % porosity) with high grain aspect ratios (i.e. >10:1). This approach makes use of a low volume fraction of multiple sintering aids, where each additive plays one or more roles in the sintering behavior of Si3N4 (i.e. densification aid, transformation aid and/or whisker growth aid). Compositions are based on various ratios of Y2O3:MgO, both with and without CaO additions. Sintering has been conducted in a nitrogen atmosphere (0.1 MPa) between 1400 and 1700°C. The effects of processing parameters (e.g. composition, sintering temperature and time) will be discussed, paying particular attention to microstructure development, including both the densification behavior and α- to β-Si3N4 transformation kinetics.

关键词： Silicon compounds

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One-pot fabrication of FePt/reduced graphene oxide composites as highly active and stable electrocatalysts for the oxygen reduction reaction

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Carbon 2014年 68卷 755-762页

作者： Dan Chen Xin Zhao Shanshan Chen Huifeng Li Xinning Fu Qingzhi Wu Shipu Li Yu Li bao-Lian Su Rodney S. Ruoff State Key Laboratory of Advanced Technology for Materials Synthesis and Processing and Biomedical Material and Engineering Center Wuhan University of Technology Wuhan 430070 China Department of Mechanical Engineering and the Materials Science and Engineering Program The University of Texas at Austin 1 University Station C2200 Austin TX 78712 USA Laboratory of Inorganic Materials Chemistry University of Namur 61 rue de Bruxelles B-5000 Namur Belgium Clare Hall College University of Cambridge Cambridge UK

FePt nanoparticles (NPs)/reduced graphene oxide (rG-O) composites have been synthesized using a one-pot strategy without surfactants. Monodisperse FePt NPs were homogenously loaded onto rG-O sheets. by controlling the concentration of dispersed graphene oxide (GO), uniform FePt flower-like nanoclusters can be obtained. FePt/rG-O composites exhibited exceptionally high electrocatalytic performance in the activity and durability for the oxygen reduction reaction (ORR), much superior to that of the commercial Pt/C (60%). The straightforward synthesis of FePt/rG-O composites provides a low-cost and high performance catalyst for the ORR, which is also a promising strategy for the synthesis of various Pt-based bimetallic alloy/rG-O composites for potential uses in catalysis and energy fields.

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Spin injection/detection using an organic-based magnetic semiconductor (vol 9, pg 638, 2010)

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NATURE materials 2010年第9期9卷 638-642页

作者： Yoo, Jung-Woo Chen, Chia-Yi Jang, H. W. bark, C. W. Prigodin, V. N. Eom, C. b. Epstein, A. J. Department of Physics The Ohio State University Columbus Ohio 43210-1117 USAJung-Woo YooV. N. Prigodin &A. J. EpsteinDepartment of Chemistry The Ohio State University Columbus Ohio 43210-1173 USAJung-Woo Yoo &A. J. EpsteinChemical Physics Program The Ohio State University Columbus Ohio 43210-1106 USAChia-Yi ChenDepartment of Materials Science and Engineering University of Wisconsin–Madison Madison Wisconsin 53706-1595 USAH. W. JangC. W. Bark &C. B. Eom

An important component of spintronics devices is the magnetic electrode, which is usually made from an inorganic alloy. However, an organic-based spin polarizer is now demonstrated, opening new possibilities for devel... 详细信息

关键词： Subject terms:Electronic materials Molecular electronics Magnetic materials

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Metal-enriched nanoparticles and black carbon:A perspective from the brazil railway system air pollution

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Geoscience Frontiers 2021年第3期12卷 624-635页

作者： bianca D.Lima Elba C.Teixeira James C.Hower Matheus S.Civeira Omar Ramírez Cheng-Xue Yang Marcos L.S.Oliveira Luis F.O.Silva Postgraduate Program in Remote Sensing and Meteorology Geosciences InstituteUniversidade Federal do Rio Grande do SulAv.Bento Gonçalves9500Porto AlegreRS 91501–970Brazil Research Department Fundação Estadual de Proteção Ambiental Henrique Luís RoesslerAv.Borges de Medeiros261Porto AlegreRS 90020–021Brazil Center for Applied Energy Research University of Kentucky2540 Research Park DriveLexingtonKY 40511USA Postgraduate Program in Mines Metallurgy and MaterialsUniversidade Federal do Rio Grande do SulAv.Bento Gonçalves9500Porto AlegreRS 91501–970Brazil Faculty of Engineering Environmental EngineeringUniversidad Militar Nueva GranadaKm 2 CajicáZipaquiráColombia Institute of Earth Science China University of Geosciences(Beijing)29 Xueyuan RdHaidian DistrictChina Department of Civil and Environmental Universidad de la CostaCUCCalle 58#55-66BarranquillaAtlanticoColombia Universidad de Lima Departamento de Ingeniería civil y Arquitectura.Avenida Javier Prado Este 4600–Santiago de Surco 1503Peru

Having a better understanding of air pollutants in railway systems is crucial to ensure a clean public *** study measured,for the first time in brazil,nanoparticles(NPs)and black carbon(bC)on two groundlevel platforms and inside trains of the Metropolitan Area of Porto Alegre(MAPA).An intense sampling campaign during thirteen consecutive months was carried out and the chemical composition of NPs was examined by advanced microscopy *** results showed that highest concentrations of the pollutants occur in colder seasons and influenced by variables such as frequency of the trains and passenger ***,internal and external sources of pollution at the stations were *** predominance of NPs enriched with metals that increase oxidative stress like Cd,Fe,Pb,Cr,Zn,Ni,V,Hg,Sn,and ba both on the platforms and inside trains,including Fe-minerals as hematite and magnetite,represents a critical risk to the health of passengers and employees of the *** interdisciplinary and multi-analytical study aims to provide an improved understanding of reported adverse health effects induced by railway system aerosols.

关键词： Nanoparticles Potential hazardous elements Environmental chemistry Human health Railway environment Indoor air quality

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