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BaTiO_(3)solid solutions co-doped with Gd^(3+)and Eu^(3+):Synthesis,structural evolution and dielectric properties

journal of Rare Earths 2024年第10期42卷 1920-1926页

作者： R.Martínez-López M.pérez-Labra j.A.Romero-Serrano f.R.Barrientos-Hernández M.Reyes-pérez M.I.Valenzuela-Carrillo G.Urbano-Reyes V.E.Reyes-Cruz G.I.Dávila-pulido Academic Area of Earth Sciences and Materials Autonomous University of Hidalgo StateRoad Pachuca-Tulancingo Km 4.5 Mineral de La Reforma.Hidalgo42184Mexico Metallurgy and Materials Department ESIQIE-IPNUPALMZacatencoCiudad de Mexico07738Mexico Autonomous University of Coahuila Boulevard Adolfo López Mateos S/nNueva RositaCoahuila26800Mexico

In this paper,the synthesis,structural evolution,and dielectric properties of BaTiO_(3)solid solutions codoped with rare earth elements(Gd^(3+)and Eu^(3+))prepared using the solid-state reaction method are *** pure precursor powders of BaCl_3,TiO_(2),Gd_(2)O_(3),and Eu_(2)O_(3)were mixed in stoichiometric proportions,ground in an agate mortar before being uniaxially pressed at 250 Mpa and sintered at 1300℃in air atmosphere for 6 h to obtain Ba_(1-3x)Gd_(2x)Ti_(1-3x)Eu_(4x)O_(3)(x=0,0.0015,0.01 and0.1).X-ray diffraction(XRD)and Rietveld's refinement results reveal the crystal phase ferroelectric tetragonal BaTiO_(3)for the samples with x=0,0.0015 and 0.01,as well as a consistent increment in the lattice parameters caused by the *** solubility limit of Gd^(3+)and Eu^(3+)in the BaTiO_(3)structure is reached for the sample with x>0.01,and the orthorhombic Eu_2TiO_(5)and monoclinic BaTi_(2)O_(5)secondary phases were *** Raman results show the characteristic peaks of ferroelectric tetragonal BaTiO_(3)around 716 cm^(-1)(LO of A1 symmetry),515 cm^(-1)(TO of A1 symmetry),and 305 cm^(-1)(B1).The maximum relative permittivity measured at 1 kHz was recorded to be 6151.8 for the sample with x=0.0015,and a decrease in the Curie temperature to 105℃with respect to the undoped sample was *** punctual microanalysis for the samples with x=0.0015,0.01,and 0.1 reveals grains composed of Ba,Ti,O,Gd,and Eu homogeneously distributed in the BaTiO_(3)*** Ba/Ti ratios for samples with x=0.0015,0.01 and 0.1 are 2.86,2.91,and 0.68,respectively,indicating substitution at the Ti site for samples with x=0.0015 and 0.01 and a substitution at the Ba site for the sample with x=0.1.

关键词： BaTiO_(3) Doping Gadolinium Europium Synthesis Rare earths

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On the analytical solution of transient friction in channel flows

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Applied Mathematics and Mechanics(English Edition) 2024年第8期45卷 1447-1466页

作者： f.j.GARCíA-GARCíA p.fARINAS-ALVARINO Department of Naval&Industrial Engineering Polytechnic School of EngineeringUniversity of A CorunaCampus Industrial de FerrolFerrol 15403A CorunaSpain Integraciones Técnicas de Seguridad S.A.Pol.Ind.Espiritu SantoC/Nobel15Cambre 15650A CorunaSpain

The transient friction in channel mean flows is the sum of two contributions,i.e.,the underlying laminar flow(ULf)and the purely turbulent component(pTC),and the contributions are analyzed separately by theoretical *** is found that,the transient friction may be higher or remarkably lower than that in equal-Reynolds number steady-state *** universal time constant for plane-parallel laminar flows is reported,and the role of the time constant in a turbulent mean flow is *** is shown that the time constant is related to the turbulence's frozen ***,a study of the logarithmic layer during the transient flow is accomplished,which shows that the logarithmic layer is destroyed.

关键词： transient friction transient flow unsteady channel flow

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Efficiency and effectiveness of systems for the treatment of domestic wastewater based on subsurface flow constructed wetlands in jarabacoa, Dominican Republic

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Water Science and Engineering 2024年第2期17卷 118-128页

作者： Yvelisse pérez Enmanuel Vargas Daniel Garcia-Cortes William Hernandez Humberto Checo Ulises jauregui-Haza Area de Ciencias Basicas y Ambientales Instituto Tecnologico de Santo Domingo(INTEC)Avenida de Los Proceres 49Los Jardines del NorteSanto Domingo 10602Dominican Republic Ministry of Environment and Natural Resources Calle Cayetano Germosen esq.Ave.LuperonEl PedregalSanto Domingo 11107Dominican Republic plan Yaque Calle Estela Geraldino 14 AltosJarabacoa 41000Dominican Republic Institute of Technologies and Applied Sciences University of HavanaHavana 10400Cuba

Constructed wetlands(CwW)are well known nature-based systems for water *** study evaluated the efficiency and effectiveness of seven domestic wastewater treatment systems based on horizontal flow CWs in jarabacoa,the Dominican *** results showed that the CWs were efficient in reducing the degree of contamination of wastewater to levels below the Dominican wastewater discharge standards for parameters such as the 5-day biochemical oxygen demand(BOD5)and chemical oxygen demand,but not for the removal of phosphorus and fecal *** addition,a horizontal flow subsurface wetland in the peri-urban area El Dorado was evaluated in terms of the performance of wastewater treatment in tropical climatic *** concentrations of heavy metals,such as zinc,copper,chromium,and iron,were found to decrease in the effluent of the wetland,and the concentrations for nickel and manganese tended to *** levels of heavy metals in the effluent were lower than the limit values of the Dominican wastewater discharge *** construction cost of these facilities was around 200 USD per population equivalent,similar to the cost in other countries in the same *** study suggested some solutions to the improved performance of CWs:selection of a microbial flora that guarantees the reduction of nitrates and nitrites to molecular nitrogen,use of endemic plants that bioaccumulate heavy metals,combination of constructed wetlands with filtration on activated carbon,and inclusion of water purification processes that allow to evaluate the reuse of treated water.

关键词： Domestic wastewater Constructed wetland BOD COD pathogens Heavy metals

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Robust hybrid bismuth perovskites as potential photocatalysts for overall water splitting

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Nano Research 2024年第5期17卷 4593-4601页

作者： Antonio j.Chacón-García Herme G.Baldovi Artem A.Babaryk Antonio Rodríguez-Diéguez Sergio Navalón Yolanda pérez Hermenegildo García patricia Horcajada Advanced porous Materials Unit IMDEA Energy InstituteAvda.Ramón y Cajal 328935 MóstolesMadridSpain Departamento de Química Universitat Politècnica de València46022 ValènciaSpain Departamento Química Inorgánica Universidad de Granada1807GranadaSpain Departamento de Biología y Geología Física y Química Inorgánica.ESCET.Universidad Rey Juan Carlos28933 MóstolesMadridSpain Instituto de tecnología química CSIC-UpV Universitat Politècnica de València(UPV)46022Spain

Organic-inorganic hybrid perovskites have gained great attention as promising photocatalysts for hydrogen ***,due to their poor stability in water,the use of aqueous hydrohalic acid solutions is specifically required for an efficient hydrogen ***,three novel photoactive lead-free hybrid perovskites based on bismuth and triazolium cations(denoted as IEf-15,IEf-16,and IEf-17(IEf stands for IMDEA energy frameworks))were synthesized and fully characterized(structural,compositional,optical,etc.).further,these solids were proposed as photocatalysts for the challenging gas phase overall water splitting(OWS)***,IEf-16 thin films exhibited a remarkable photocatalytic activity in both H_(2) and O_(2) evolution,as a consequence of its appropriate bandgap and energy-band alignment,achieving hydrogen evolution rates ofμmol·g_(H_(2))^(-)1846 and 360 after 24 h under ultraviolet-visible(UV-vis)irradiation or simulated solar irradiation,*** study additionally highlights the remarkable structural and photochemical stability of IEf-16 under different operational conditions(*** volume,irradiation and temperature),paving the way for green hydrogen production from OWS using perovskite-based photocatalysts.

关键词： bismuth-based hybrid perovskites thin films photocatalysis overall water splitting green hydrogen

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Impact of device resistances in the performance of graphene‑based terahertz photodetectors

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frontiers of Optoelectronics 2024年第2期17卷 87-97页

作者： O.Castelló Sofía M.López Baptista K.Watanabe T.Taniguchi E.Diez j.E.Velázquez-pérez Y.M.Meziani j.M.Caridad j.A.Delgado-Notario Department of Applied physics University of Salamanca37008 SalamancaSpain Unidad de Excelencia en Luz y Materia Estructurada(LUMES) University of Salamanca37008 SalamancaSpain Research Center for Electronic and Optical Materials National Institute for Materials Science1-1 NamikiTsukuba 305-0044Japan Research Center for Materials Nanoarchitectonics National Institute for Materials Science1-1 NamikiTsukuba 305-0044Japan Nanotechnology Group USAL-NanolabUniversity of Salamanca37008 SalamancaSpain

In recent years,graphene field-effect-transistors(GfETs)have demonstrated an outstanding potential for terahertz(THz)photodetection due to their fast response and *** features are essential to enable emerging THz applications,including 6G wireless communications,quantum information,bioimaging and ***,the overall performance of these photodetectors may be utterly compromised by the impact of internal resistances presented in the device,so-called access or parasitic *** this work,we provide a detailed study of the influence of internal device resistances in the photoresponse of high-mobility dual-gate GfET *** dual-gate architectures allow us to fine tune(decrease)the internal resistance of the device by an order of magnitude and consequently demonstrate an improved responsivity and noise-equivalent-power values of the photodetector,*** results can be well understood by a series resistance model,as shown by the excellent agreement found between the experimental data and theoretical *** findings are therefore relevant to understand and improve the overall performance of existing high-mobility graphene photodetectors.

关键词： Graphene THz photodetector field-effect transistor plasmonic

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Biomass gasification,catalytic technologies and energy integration for production of circular methanol:New horizons for industry decarbonisation

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journal of Environmental Sciences 2024年第6期140卷 306-318页

作者： Luis f.Bobadilla Lola Azancot Miriam González-Castañ Estela Ruíz-López Laura pastor-pérez francisco j.Durán-Olivencia Runping Ye Katie Chong paula HBlanco-Sánchez Zenthao Wu Tomás R.Reina joséA.Odriozola Departamento de Química Inorgánica e Instituto de Ciencia de Materiales de Sevilla Centro Mixto CSIC-Universidad de SevillaAvda.Américo Vespucio 49Sevilla 41092Spain Departamento de Ingeniería Universidad Loyola AndalucíaAvda.de Las Universidades s/nSevilla 41704Spain Key Laboratory of jiangxi province for Environment and Energy Catalysis School of Chemistry and Chemical EngineeringNanchang UniversityNanchang330031China Energy and Bioproducts Research Institute(EBRI) Aston UniversityBirminghamB47ETUnited Kingdom Department of Chemical and process Engineering University of SurreyGuildfordGU27XHUnited Kingdom

The Intergovernmental panel on Climate Change(IpCC)recognises the pivotal role of renewable energies in the future energy system and the achievement of the zero-emission *** implementation of renewables should provide major opportunities and enable a more secure and decentralised energy supply *** fuels provide long-term solutions for the transport sector,particularly for applications where fuels with high energy density are *** addition,it helps reducing the carbon footprint of these sectors in the *** on biomass characteristics feedstock is essential for scaling-up gasification from the laboratory to *** review deals with the transformation biogenic residues into a valuable bioenergy carrier like biomethanol as the liquid sunshine based on the combination of modified mature technologies such as gasification with other innovative solutions such as membranes and microchannel *** abatement is a critical process in product gas upgrading since tars compromise downstream processes and equipment,for this,membrane technology for upgrading syngas quality is discussed in this *** reactor technology with the design of state-of-the-art multifunctional catalysts provides a path to develop decentralised biomethanol synthesis from biogenic ***,the development of a process chain for the production of(i)methanol as an intermediate energy carrier,(ii)electricity and(iii)heat for decentralised applications based on biomass feedstock flexible gasification,gas upgrading and methanol synthesis is analysed.

关键词： Biogenic residues Gasification Biomethanol Circular Economy Microreactors

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Modelling dynamic pantograph loads with combined numerical analysis

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Railway Engineering Science 2024年第1期32卷 81-94页

作者： f.f.jackson R.Mishra j.M.Rebelo j.Santos p.Antunes j.pombo H.Magalhaes L.Wills M.Askill School of Computing and Engineering University of HuddersfieldHuddersfieldUK School of Computing and Engineering Institute of Railway ResearchUniversity of HuddersfieldHuddersfieldUK IDMEC Instituto Superior TecnicoUniversidade de LisboaLisbonPortugal ISEL Instituto Politecnico de LisboaLisbonPortugal Hitachi Rail Newton AycliffeUK Wabtec/Brecknell Willis ChardUK

Appropriate interaction between pantograph and catenary is imperative for smooth operation of electric *** heights of overhead lines to accommodate level crossings,overbridges,and tunnels pose significant challenges in maintaining consistent current collection performance as the pantograph aerodynamic profile,and thus aerodynamic load changes significantly with operational *** research aims to analyse the global flow characteristics and aerodynamic forces acting on individual components of an HSX pantograph operating in different configurations and orientations,such that the results can be combined with multibody simulations to obtain accurate dynamic insight into contact ***,computational fluid dynamics simulations are used to investigate the pantograph component loads in a representative setting,such as that of the recessed cavity on a Class 800 *** an aerodynamic perspective,this study indicates that the total drag force acting on non-fixed components of the pantograph is larger for the knuckle-leading orientation rather than the knuckle-trailing,although the difference between the two is found to reduce with increasing pantograph *** the aerodynamic loads acting on individual components with multibody tools allows for realistic dynamic insight into the pantograph *** results obtained show how considering aerodynamic forces enhance the realism of the models,leading to behaviour of the pantograph-catenary contact forces closely matching that seen in experimental tests.

关键词： pantograph-catenary interaction pantograph aerodynamics Computational fluid dynamics pantograph loads Current collection performance

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Single atom Cu-N-C catalysts for the electro-reduction of CO_(2) to CO assessed by rotating ring-disc electrode

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journal of Energy Chemistry 2024年第1期88卷 169-182,I0004页

作者： S.pérez-Rodríguez M.Gutiérrez-Roa C.Giménez-Rubio D.Ríos-Ruiz p.Arévalo-Cid M.V.Martínez-Huerta A.Zitolo M.j.Lázaro D.Sebastián Instituto de Carboquímica(CSIC) Miguel Luesma Castán 450018 ZaragozaSpain Instituto de Catálisis y petroleoquímica(CSIC) Marie Curie 228049 MadridSpain Synchrotron SOLEIL L’Orme des MerisiersDépartementale 12891190France

The electrochemical CO_(2) reduction reaction(CO_(2)RR) to controllable chemicals is considered as a promising pathway to store intermittent renewable energy. Herein, a set of catalysts based on copper-nitrogendoped carbon xerogel(Cu-N-C) are successfully developed varying the copper amount and the nature of the copper precursor, for the efficient CO_(2)RR. The electrocatalytic performance of Cu-N-C materials is assessed by a rotating ring-disc electrode(RRDE), technique still rarely explored for CO_(2)RR. for comparison, products are also characterized by online gas chromatography in a H-cell. The as-synthesized Cu-NC catalysts are found to be active and highly CO selective at low overpotentials(from -0.6 to -0.8 V ***) in 0.1 M KHCO_(3), while H_(2) from the competitive water reduction appears at larger overpotentials(-0.9 V vs. RHE). The optimum copper acetate-derived catalyst containing Cu-N_(4) moieties exhibits a CO_(2)-to-CO turnover frequency of 997 h^(-1) at -0.9 V vs. RHE with a H_(2)/CO ratio of 1.8. These results demonstrate that RRDE configuration can be used as a feasible approach for identifying electrolysis products from CO_(2)RR.

关键词： Cu-N-C Carbon xerogel Rotating ring disc electrode Carbon dioxide reduction reaction Carbon monoxide

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Selection of digital fabrication technique in the construction industry--A multi-criteria decision-making approach

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frontiers of Structural and Civil Engineering 2024年第7期18卷 977-997页

作者： M.p.SALAIMANIMAGUDAM j.jAYApRAKASH Department of Structural and Geotechnical Engineering School of Civil EngineeringVellore Institute of TechnologyVellore 632014India

Digital fabrication techniques,in recent decades,have provided the basis of a sustainable revolution in the construction ***,selecting the digital fabrication method in terms of manufacturability and functionality requirements is a complex *** paper presents alternatives and criteria for selection of digital fabrication techniques by adopting the multi-criteria decision-making *** alternatives considered in the study are concrete three-dimensional(3D)printing,shotcrete,smart dynamic casting,material intrusion,mesh molding,injection concrete 3D printing,and thin forming *** criteria include formwork utilization,reinforcement incorporation,geometrical complexity,material enhancement,assembly complexity,surface finish,and build *** demonstrates different multi-criteria decision-making techniques,with both subjective and objective weighting *** given ranking is based on the current condition of digital fabrication in the construction *** study reveals that in the selection of digital fabrication techniques,the criteria including reinforcement incorporation,build area,and geometrical complexity play a pivotal role,collectively accounting for nearly 70% of the overall *** the evaluated techniques,concrete 3D printing emerged as the best performer,however the shotcrete and mesh molding techniques in the second and third positions.

关键词： digital fabrication multicriteria decision-making concrete 3D printing

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Bulking Up the Bay-position Substituents Enables Enhanced Selectivity of C_(s)‑Symmetric Boron Subphthalocyanine−Subnaphthalocyanine Hybrids

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precision Chemistry 2024年第4期2卷 161-181页

作者： Nina f.farac Alan j.Lough Timothy p.Bender Department of Chemical Engineering and Applied Chemistry University of TorontoTorontoOntario M5S 3E5Canada Department of Chemistry University of TorontoTorontoOntario M5S 3H6Canada Department of Materials Science and Engineering University of TorontoTorontoOntario M5S 3E4Canada Department of Mechanical and Industrial Engineering University of TorontoTorontoOntario M5S 3G8Canada

The precise synthesis of subporphyrinoid hybrids withπ-expanded topologies and unique material properties plays a promising role in the design of functional ***,selective,and controllable routes to boron subphthalocyanine−subnaphthalocyanine hybrids,Bsub(pc_(3‑p)-Nc_(p))s,are desirable for this purpose yet synthetically challenging due to random mixtures of C_(s-),C_(3v-),and,in some cases,C_(1)-symmetric compounds that form during traditional statistical mixed ***,we addressed this issue by developing a sterically driven mixed cyclotrimerization with enhanced selectivity for the targeted C_(s)-symmetric hybrid and complete suppression of sterically crowded macrocyclic *** process,coupled with a rationally designed precursor bearing bulky phenyl substituents,enabled the synthesis and characterization of bay-position phenylated ph_(2)-(R_(p))_(8)Bsub(pc_(2)-Nc_(1))hybrids with halogens(Rp=Cl or f)in their peripheral isoindole *** selectivity ranged between 59 and 72%with remarkable yields,significantly higher than that of conventional mixed *** findings were augmented by theoretical calculations on precursor Lewis basicity as guiding principles into hybrid macrocycle ***,the incorporation of unfused phenyl groups and halogen atoms into the hybrid framework resulted in fine-tuned optical,structural,electronic,and electrochemical *** straightforward approach achieved improved selectivity and controlled narrowing of the product distribution,affording the efficient synthesis of structurally sophisticated Bsub(pc_(2)-Nc_(1))*** then expands the library of 3-dimensionalπ-extended macrocycles for use in a range of applications,such as in optoelectronic devices with precisely tailored optical properties.

关键词： subphthalocyanine hybrids low-symmetry aromatic macrocycle selective cyclotrimerization sterically driven chemistry broad absorption material properties

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