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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 high-sensitivity.Such features are essential to enable emerging THz applications,including 6G wireless communications,quantum information,bioimaging and security.However,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 resistances.In this work,we provide a detailed study of the influence of internal device resistances in the photoresponse of high-mobility dual-gate GFET detectors.Such 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,respectively.Our results can be well understood by a series resistance model,as shown by the excellent agreement found between the experimental data and theoretical calculations.These 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

Error field penetration in j-TEXT tokamak based on two-fluid drift-MHD model

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Chinese Physics B 2024年第4期33卷 545-551页

作者：王文徐涛张仪 the j-TEXT team State Key Laboratory of Advanced Electromagnetic Technology International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma PhysicsSchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China

An externally generated resonant magnetic perturbation can induce complex non-ideal MHD responses in their resonant surfaces.We have studied the plasma responses using Fitzpatrick's improved two-fluid model and program LAYER.We calculated the error field penetration threshold for j-TEXT.In addition,we find that the island width increases slightly as the error field amplitude increases when the error field amplitude is below the critical penetration value.However,the island width suddenly jumps to a large value because the shielding effect of the plasma against the error field disappears after the penetration.By scanning the natural mode frequency,we find that the shielding effect of the plasma decreases as the natural mode frequency decreases.Finally,we obtain the m/n=2/1 penetration threshold scaling on density and temperature.

关键词： plasma responses drift-MHD model error field penetration

Reuse of port industrial heritage in tourist cities:Shipyards as case studies

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Frontiers of Architectural Research 2024年第1期13卷 164-183页

作者： María j.Andrade Eduardo jiménez-Morales Rachel Rodríguez-Ramos Pablo Martínez-Ramírez Department of Art and Architecture School of ArchitectureMalaga UniversityMalaga 29013Spain

The progressive deindustrialisation of many western cities since the 1980s has led to many industrial zones linked to port activities being abandoned or falling into disuse.Cities such as Barcelona,Naples,Lisbon,Amsterdam,and Hamburg have port industrial complexes of high tangible and intangible heritage value that could totally or partially disappear,resulting in an irreparable loss of their scientific,architectural,social,technological,and historical values.With that in mind,Adaptive Reuse(AR)of the built heritage allows the industrial memory of the ports to be preserved by turning them into new functional centres within the existing urban structure.That occurs in the context of the contemporary challenges of those cities,such as touristification,the circular economy and climate change,while guaranteeing the life cycle of those buildings.This article analyses two case studies—the Nederlandsche Scheepsbouw Maatschappij(NDSM)and the Rotterdamsche Droogdok Maatschappij(RDM)shipyards,both in the Netherlands—in order to contribute to the knowledge of AR of Port Industrial Heritage.They are two examples of good practices in port industrial heritage interventions,where the factors behind their acclaim can be easily highlighted.A multi-scale methodology is therefore used and tailored to the case of port industrial heritage,based on analysing previous studies of the heritage in different spheres and on different scales.A relationship matrix tool is thus defined.It enables a comparative study to be conducted,using key variables and indicators,and considering qualitative and quantitative data.That provides extensive output information for each case study,which is summarised in the most favourable factors for the success of the AR of this port industrial heritage.

关键词： Industrial heritage Port-city Adaptive reuse Best practices Circular economy HUL Touristification

Solution of the Center Problem for a Class of Polynomial Differential Systems

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Acta Mathematica Sinica,English Series 2024年第7期40卷 1685-1696页

作者： Chang jian Liu jaume Llibre Rafael Ramírez Valentín Ramírez School of Mathematics(Zhuhai) Sun Yat-sen UniversityZhuhai519086P.R.China Departament de Matemàtiques Universitat Autònoma de Barcelona08193BellaterraBarcelonaCataloniaSpain Departament d’Enginyeria Informàtica i Matemàtiques Universitat Rovira i VirgiliAvinguda dels Paiïsos Catalans 2643007TarragonaCataloniaSpain

Consider the polynomial differential system of degree m of the form x=-y(1+μ(a_(2)x-a_(1)y))+x(v(a_(1)x+a_(2)y)+Ω_(m-1)(x,y)),y=x(1+μ(a_(2)x-a_(1)y))+y(v(a_(1)x+a_(2)y)+Ω_(m-1)(x,y)),whereμandνare real numbers such that(μ^(2)+v^(2))(μ+v(m-2))(a_(1)^(2)+a_(2)^(2))≠m>2 andΩ_(m−1)(x,y)is a homogenous polynomial of degree m−1.A conjecture,stated in j.Differential Equations 2019,suggests that whenν=1,this differential system has a weak center at the origin if and only if after a convenient linear change of variable(x,y)→(X,Y)the system is invariant under the transformation(X,Y,t)→(−X,Y,−t).For every degree m we prove the extension of this conjecture to any value ofνexcept for a finite set of values ofμ.

关键词： Center problem polynomial differential system

Analysis of ancient mass extinction recoveries in marine environments: generating strategies for managing outcomes of the current mass extinction

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National Science Review 2024年第1期11卷 8-10页

作者： David j.Bottjer Department of Earth Sciences University of Southern California

The defining feature of a mass extinction and its associated recovery is the global amount of extinction that occurred[1]. However, there is finer-scale detail to the story, as seen in the ongoing modern mass extinction(the sixth mass extinction), which exhibits variable effects among marine ecosystems and environments, and hence geographic areas [1].

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Global weirding at mass extinction horizons

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National Science Review 2024年第1期11卷 10-12页

作者： Gregory j.Retallack Department of Earth Sciences University of Oregon

A strong motivation for studying mass extinctions is understanding how current climatic and biodiversity crises will affect creatures living on land such as ourselves. Perhaps the question is: how bad can it get? In that case, terrestrial Permian-Triassic mass extinctions are an irresistible worst-case scenario [1].

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Necrotic enteritis and antibiotic-free production of broiler chickens:Challenges in testing and using alternative products

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Animal Nutrition 2024年第1期16卷 288-298页

作者： Robert j.Moore School of Science RMIT University

The global trend towards raising broiler chickens without the use of in-feed antibiotics(IFAs) means that there is an ongoing need to develop alternative treatments capable of delivering the benefits that IFAs previously provided. IFAs supported the productivity performance of chickens and played a key role in maintaining their health. Necrotic enteritis(NE) is an important disease of broilers that affects health,productivity, and welfare, and was previously well controlled by IFAs. However, with the reduction in IFA use, NE is resurgent in some countries. Vaccines and various feed additives, including pre-, pro-, and postbiotics, phytobiotics, fatty acids, and phage therapies have been introduced as alternative methods of NE control. While some of these feed additives have specific activity against the NE pathogen, Clostridium perfringens, most have the more general goal of reinforcing gut health. Extensive reviews of the effects of many of these feed additives on gut health have been published recently. Hence, rather than cover previously well reviewed areas of research this review focuses on the challenges and pitfalls in undertaking experimental assessment of alternative NE treatments and translating laboratory research to real world commercial production settings. The review is based on the author's particular experience,reading, thoughts, and analysis of the available information and inevitably presents a particular understanding that is likely to be at odds with others thinking on these issues. It is put forward to stimulate thinking and discussion on the issues covered.

关键词： Necrotic enteritis

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 generation.However,due to their poor stability in water,the use of aqueous hydrohalic acid solutions is specifically required for an efficient hydrogen evolution.Herein,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)reaction.Accordingly,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,respectively.This study additionally highlights the remarkable structural and photochemical stability of IEF-16 under different operational conditions(i.***.water 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

Storing Freshwater Versus Storing Electricity in Power Systems with High Freshwater Electric Demand

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journal of Modern Power Systems and Clean Energy 2024年第2期12卷 323-333页

作者： Mubarak j.Al-Mubarak Antonio j.Conejo Department of Electrical and Computer Engineering The Ohio State UniversityColumbusOHUSA Department of Electrical Engineering Kuwait UniversityP.O.Box 5969Safat 13060Kuwait Department of Integrated Systems Engineering and the Department of Electrical and Computer Engineering The Ohio State UniversityColumbusOH 43210USA IEEE

We consider a power system whose electric demand pertaining to freshwater production is high(high freshwater electric demand),as in the Middle East,and investigate the tradeoff of storing freshwater in tanks versus storing electricity in batteries at the day-ahead operation stage.Both storing freshwater and storing electricity increase the actual electric demand at valley hours and decrease it at peak hours,which is generally beneficial in term of cost and reliability.But,to what extent?We analyze this question considering three power systems with different generation-mix configurations,i.e.,a thermal-dominated mix,a renewable-dominated one,and a fully renewable one.These generation-mix configurations are inspired by how power systems may evolve in different countries in the Middle East.Renewable production uncertainty is compactly modeled using chance constraints.We draw conclusions on how both storage facilities(freshwater and electricity)complement each other to render an optimal operation of the power system.

关键词： Power system operation freshwater production and transportation coordination day-ahead scheduling