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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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Waste Valorization from brazilian Nepheline Syenite Processing as a Strategic Approach to Advancing the Circular Economy

SSRN

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SSRN 2023年

作者： Santos, Diego Haltiery Rosa, Laura Pereira Alves, Cleidson Rosa Simão, Lisandro Arcaro, Sabrina Klegues Montedo, Oscar Rubem Raupp-Pereira, Fabiano Graduate Program in Materials Science and Engineering University of the Extreme South of Santa Catarina Criciúma88806-000 Brazil Department of Civil Engineering Federal Institute of Santa Catarina Criciúma88813-600 Brazil Research Group on Sustainability and Waste Management Postgraduate Program in Environmental Technology University of Ribeirão Preto Ribeirão Preto14096-900 Brazil Brazil

The growing disparity between the high extraction of natural resources and low use of waste as alternative mineral resources will aggravate the scarcity of natural reserves. Therefore, the current linear economy model must be converted to sustainable economic models, such as the circular economy. To achieve this transition, it is important that waste recovery strategies are implemented with a continuous search for solutions for these materials. Thus, this study investigates the waste from the processing of nepheline syenite stone, to promote its valorization as an alternative mineral resource. The classification, potentiality, quantity/viability and applicability (CPQvA) criteria are used as tools to aid decision-making for the waste valorization. The environmental, physical, chemical, morphological, and durability characteristics of nepheline syenite waste (NSW) are analyzed. The results showed evidence for the substitution of NSW for up to 100% of fine aggregates and 25% of Portland cement in civil construction. Furthermore, NSW yields recoveries of more than 90% of potassium for use in agriculture, and up to 70% of iron ore for use in steelworks. Therefore, the results indicate that NSW is viable for different applications, contributing to industrial symbiosis and a strategy for advancing the circular economy. © 2023, The Authors. All rights reserved.

关键词： Sustainable development

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Unifying femtosecond and picosecond single-pulse magnetic switching in Gd-Fe-Co

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Physical Review b 2021年第10期103卷 104422-104422页

作者： F. Jakobs T. A. Ostler C.-H. Lambert Y. Yang S. Salahuddin R. b. Wilson J. Gorchon J. bokor U. Atxitia Dahlem Center for Complex Quantum Systems and Fachbereich Physik Freie Universität Berlin 14195 Berlin Germany Département de Physique Universitè de Liége (B5) B-4000 Liége Belgium College of Business Technology and Engineering Sheffield Hallam University Howard Street Sheffield S1 1WB United Kingdom Department of Electrical Engineering and Computer Sciences University of California Berkeley California 94720 USA Department of Materials Science and Engineering University of California Berkeley California 94720 USA Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley California 94720 USA Department of Mechanical Engineering and Materials Science and Engineering Program University of California Riverside California 92521 USA

Many questions are still open regarding the physical mechanisms behind the magnetic switching in Gd-Fe-Co alloys by single optical pulses. Phenomenological models suggest a femtosecond scale exchange relaxation between sublattice magnetization as the driving mechanism for switching. The recent observation of thermally induced switching in Gd-Fe-Co by using both several picosecond optical laser pulse as well as electric current pulses has questioned this previous understanding. This has raised the question of whether or not the same switching mechanics are acting at the femtosecond and picosecond scales. In this work, we aim at filling this gap in the understanding of the switching mechanisms behind thermal single-pulse switching. To that end, we have studied experimentally thermal single-pulse switching in Gd-Fe-Co alloys, for a wide range of system parameters, such as composition, laser power, and pulse duration. We provide a quantitative description of the switching dynamics using atomistic spin dynamics methods with excellent agreement between the model and our experiments across a wide range of parameters and timescales, ranging from femtoseconds to picoseconds. Furthermore, we find distinct element-specific damping parameters as a key ingredient for switching with long picosecond pulses and argue that switching with pulse durations as long as 15 ps is possible due to a low damping constant of Gd. Our findings can be easily extended to speed up dynamics in other contexts where ferrimagnetic Gd-Fe-Co alloys have been already demonstrated to show fast and energy-efficient processes, e.g., domain-wall motion in a track and spin-orbit torque switching in spintronics devices.

关键词： Demagnetization Magnetic interactions Magnetic order Magnetism Spin dynamics Ultrafast magnetic effects

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FIELD SAMPLING OF RESIDUAL AVIATION GASOLINE IN SANDY SOIL

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GROUND WATER MONITORING AND REMEDIATION 1991年第2期11卷 107-120页

作者： OSTENDORF, DW LEACH, LE HINLEIN, ES XIE, YF 1 David W. Ostendorf is an associate professor in the Environmental Engineering Program of the Civil Engineering Department at the University of Massachusetts (Civil Engineering Department University of Massachusetts Amherst MA 01003). His research interests include unconfined aquifer contamination hazardous waste site remediation and analytical modeling of problems in environmental fluid mechanics. Dr. Ostendorf is a registered professional engineer in Massachusetts and a member of the American Geophysical Union American Society of Civil Engineers Soil Science Society of America Water Pollution Control Federation and Association of Environmental Engineering Professors as well as the National Water Well Association.2 Lowell E. Leach is an environmental engineer with the Robert S. Kerr Environmental Research Laboratory of the U.S. Environmental Protection Agency (RS Kerr Environmental Research Laboratory U.S. EPA P.O. Box 1198 Ada OK74820). Leach received his B.S. ingeological engineering at the University of Oklahoma in 1959 and has been a registered professional engineer in Oklahoma since 1966. With 29 years of experience in field applications of geological engineering he is responsible for developing methodology for sampling ground water and subsurface materials for the Robert S. Kerr Environmental Research Laboratory.3 Erich S. Hinlein is a research assistant in the Environmental Engineering Program of the Civil Engineering Department at the University of Massachusetts (Civil Engineering Department University of Massachusetts Amherst MA 01003). His research interests include ground water pollution hazardous waste site investigation and transport processes in unconfined aquifers. Hinlein graduated with a B.S. in electrical and computer engineering from the University of Massachusetts at Amherst in May 1985 and entered the Environmental Engineering Master's Degree Program in January 1989.4 Yuefeng Xie is a postdoctoral research associate in the Environmental Engineering Program of the Civil E

Two complementary field sampling methods for the determination of residual aviation gasoline content in the contaminated capillary fringe of a fine, uniform, sandy soil were investigated. The first method featured field extrusion of core barrels into pint-size Mason jars, while the second consisted of laboratory partitioning of intact stainless steel core sleeves. The barrel extrusion procedure involved jar headspace sampling in a nitrogen-filled glove box, which delineated the 0.7m thick residually contaminated interval for subsequent core sleeve withdrawal from adjacent boreholes. Soil samples removed from the Mason jars (in the field) and sleeve segments (in the laboratory) were subjected to methylene chloride extraction and gas chromatographic analysis to compare their aviation gasoline content. The barrel extrusion sampling method yielded a vertical profile with 0.10m resolution over an essentially continuous 5.0m interval from the ground surface to the water table. The sleeve segment alternative yielded a more resolved 0.03m vertical profile over a shorter 0.8m interval through the capillary fringe. The two methods delivered precise estimates of the vertically integrated mass of aviation gasoline at a given horizontal location, and a consistent view of the vertical profile as well. In the latter regard, a 0.2m thick lens of maximum contamination was found in the center of the capillary fringe, where moisture filled all voids smaller than the mean pore size. The maximum peak was resolved by the core sleeve data, but was partially obscured by the barrel extrusion observations, so that replicate barrels or a half-pint Mason jar size should be considered for data supporting vertical transport analyses in the absence of sleeve partitions.

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Low Resistivity-Highly Transparent Zno:Ga Tco's Grown by Laser Ablation

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MRS Online Proceedings Library (OPL) 2011年第1期397卷 247-247页

作者： J. M. Siqueiros J.A. Díaz O. Contreras G.A. Hirata J. McKittrick Instituto de Física-UNAM Apdo. Postal 2681 Ensenada B.C. C.P. 22860 México. Dept. of Applied Mechanics and Engineering Sciences and Materials Science Program University of California San Diego La Jolla CA 92093-0411

Highly transparent with low electrical resistivity gallium-doped zinc oxide (ZnO:Ga) thin films were prepared on glass by Pulsed Laser Deposition at different substrate temperatures. ZnO:Ga evaporation targets were prepared by pressing and sintering powder materials obtained with a novel combustion synthesis *** excellent transmittance of more than 85% in the visible range and a low sheet resistance value as low as 13 Ω/sq. were measured on a 200 nm thickness film grown at Ts=300°C. From optical measurements we observed an increase in the ZnO:Ga bandgap when the substrate temperature is raised from 150°C to 300°C. With this, a remarkable improvement in the blue-green region transmittance is obtained.X-Ray diffraction patterns indicate that the films grow highly oriented in the basal plane direction (c-axis) of the hexagonal ZnO grains.

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CaO/Al2O3based fibers produced by solution blow spinning as a potential bifunctional catalyst for sorption-enhanced steam methane reforming

CaO/Al2O3based fibers produced by solution blow spinning as ...

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International Renewable Energy Congress

作者： Thamyscira H. S. Silva Moisés R. Cesário Cédric Gennequin Edmond Abi-Aad Vinícius D. Silva Daniel A. Macedo Unité de Chimie Environnementale et Interactions sur le Vivant - UCEIV Université du Littoral Côté d'Opale - ULCO Dunkerque France Materials Science and Engineering Postgraduate Program - PPCEM Universidade Federal da Paraíba - UFPB João Pessoa Brazil

ISBN: (数字)9781728155722

ISBN: (纸本)9781728155739

Changes for cleaner energy production are strongly demanded by society. In this perspective, researchers have been developing material that capture CO 2 and increase the production of H 2 . In this work, we highlight the potential of producing porous calcium aluminate fibers for application in Sorption-Enhanced Steam Methane Reforming (SESMR) through a relatively simple technique known as Solution blow Spinning (SbS). The fibers produced have a greater surface area and a comparable conversion rate of methane than materials produced by conventional synthesis techniques.

关键词： Catalysis Methane Calcium Spinning Optical fiber networks Surface morphology Nickel

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boosting the Photocatalytic Activity of G-C3n4/Zno Heterojunctions Through Optimal Control of Mass Ratio

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SSRN 2022年

作者： da Silva, Fausthon Fred da Silva, Rodolfo bezerra Silva, Thayse R. de Macedo, Daniel Araujo Su, bo Biomaterials Engineering Bristol Dental School University of Bristol Lower Maudlin Street BristolBS1 2LY United Kingdom PB João Pessoa58051-900 Brazil RN Mossoró59610-090 Brazil Materials Science and Engineering Postgraduate Program UFPB João Pessoa58051-900 Brazil

Carbon nitride (CN, g-C3N4) has emerged as a promising high-activity photocatalyst, despite some disadvantages like fast electron-hole recombination. The formation of CN-based heterojunctions is a viable strategy to overcome unwanted recombination processes. However, the precise control of the experimental parameters during the heterojunction formation is still needed to boost the photocatalytic efficiency. Herein, the influence of the mass ratio on the photocatalytic performance of CN/ZnO heterojunctions was investigated. The samples were obtained at room temperature via impregnation method and ultrasonic treatment. Heterojunctions were characterised by XRD and FT-IR, and interactions between the components were evidenced by the shifts in the diffraction patterns and vibrational spectra. The morphologies were investigated via SEM/TEM, confirming the formation of heterojunction interfaces. A strong influence of the CN/ZnO ratio was found on bandgaps, crystallite sizes. Photocatalytic activity was evaluated using rhodamine b dye in aqueous solution. High photocatalytic performances were obtained for CN/ZnO ≥ 1, and the best ratio was 2. The control of mass ratio changed the formation mechanism from type II heterojunction (CN/ZnO © 2022, The Authors. All rights reserved.

关键词： Carbon nitride

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