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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

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

Development of novel 5-FU modified siRNA against BCL-2 with enhanced efficacy and vehicle-free cellular uptake

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Genes & Diseases 2024年第1期11卷 23-25页

作者： Andrew Fesler Ga-ram Hwang jingfang ju Department of Pathology Renaissance School of MedicineStony Brook UniversityStony BrookNY 11794USA The Northport Veteran's Administration Medical Center NorthportNY 11768USA Curamir Therapeutics Inc. WoburnMA 01801USA

One of the major obstacles for nucleic acid-based medicine is cellular uptake due to the concern of efficiencyand potential toxicity of the vehicle.In this work,we developed a novel approach to eliminate the need for a vehicle to allow for the cellular uptake of siRNA-based therapy with a unique modification strategy that also further enhances therapeutic efficacy.This discovery may be of great importance for the development of siRNA-based therapeutics as cellular uptake remains a critical challenge.In this study,we have tested the potential of this modification strategy for siRNA using a siRNA that targets B-cell lymphoma-2(BCL-2).

关键词： eliminate uptake modified

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

Multinuclear MR and MRI study of lithium-ion cells using a variable field magnet and a fixed frequency RF probe

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Magnetic Resonance Letters 2024年第1期4卷 10-20页

作者： Andrés ramírez Aguilera Florin Marica Kevin j.Sanders Md Al Raihan C.Adam Dyker Gillian R.Goward Bruce *** UNB MRI Centre Department of PhysicsUniversity of New BrunswickFrederictonNew BrunswickE3B 5A3Canada Department of Chemistry McMaster UniversityHamiltonOntarioL8S 4L8Canada Department of Chemistry University of New BrunswickFrederictonNew BrunswickE3B 5A3Canada

An exploratory multinuclear magnetic resonance(MR)and magnetic resonance imaging(MRI)study was performed on lithium-ion battery cells with ^(7)Li,^(19)F,and ^(1)H measurements.A variable field superconducting magnet with a fixed frequency parallel-plate radiofrequency(RF)probe was employed in the study.The magnetic field was changed to set the resonance frequency of each nucleus to the fixed RF probe frequency of 33.7 MHz.Two cartridge-like lithium-ion cells,with graphite anodes and LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2)(NMC)cathodes,were interrogated.One cell was pristine,and one was charged to a cell voltage of 4.2 V.The results presented demonstrate the great potential of the variable field magnet approach in multinuclear measurement of lithium-ion batteries.These methods open the door for developing faster and simpler methods for detecting,quantifying,and interpreting MR and MRI data from lithium-ion and other batteries.

关键词： Multinuclear MR/MRI Variable field magnet Lithium-ion battery Parallel-plate rf probe

Linking leaf elemental traits to biomass across forest biomes in the Himalayas

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Science China Earth Sciences 2024年第5期67卷 1518-1528页

作者： Nita DYOLA Eryuan LIANG josep PEÑUELAS j.julio CAMARERO Shalik ram SIGDEL Sugam ARYAL Wentao LIN Xiang LIU Yongwen LIU Xingliang XU Sergio ROSSI State Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Laboratoire sur lesécosystèmes terrestres boréaux Département des Sciences FondamentalesUniversitédu QuébecàChicoutimi555Boulevard de l′UniversitéChicoutimi(QC)G7H2B1Canada CSIC Global Ecology Unit CREAF-CSIC-UABBellaterraE-08193 CataloniaSpain CREAF Cerdanyola del VallèsE-08193 CataloniaSpain Instituto Pirenaico de Ecología(IPE-CSIC) Avenida Montañana 1005Zaragoza 50059Spain Friedrich-Alexander-Universität Erlangen-Nürnberg Institut für GeographieErlangen 91058Germany State Key Laboratory of Grassland Agro-Ecosystems College of EcologyLanzhou UniversityLanzhou 730000China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China

Plants require a number of essential elements in different proportions for ensuring their growth and development.The elemental concentrations in leaves reflect the functions and adaptations of plants under specific environmental conditions.However,less is known about how the spectrum of leaf elements associated with resource acquisition,photosynthesis and growth regulates forest biomass along broad elevational gradients.We examined the influence of leaf element distribution and diversity on forest biomass by analyzing ten elements(C,N,P,K,Ca,Mg,Zn,Fe,Cu,and Mn)in tree communities situated every 100 meters along an extensive elevation gradient,ranging from the tropical forest(80 meters above sea level)to the alpine treeline(4200 meters above sea level)in the Kangchenjunga Landscape in eastern Nepal Himalayas.We calculated communityweighted averages(reflecting dominant traits governing biomass,i.e.,mass-ratio effect)and functional divergence(reflecting increased trait variety,i.e.,complementarity effect)for leaf elements in a total of 1,859 trees representing 116 species.An increasing mass-ratio effect and decreasing complementarity in leaf elements enhance forest biomass accumulation.A combination of elements together with elevation explains biomass(52.2%of the variance)better than individual elemental trait diversity(0.05%to 21%of the variance).Elevation modulates trait diversity among plant species in biomass accumulation.Complementarity promotes biomass at lower elevations,but reduces biomass at higher elevations,demonstrating an interaction between elevation and complementarity.The interaction between elevation and mass-ratio effect produces heterogeneous effects on biomass along the elevation gradient.Our research indicates that biomass accumulation can be disproportionately affected by elevation due to interactions among trait diversities across vegetation zones.While higher trait variation enhances the adaptation of species to environmental changes,it reduces biomass accumulation,especially at higher elevat

关键词： Ecosystem function Elevational gradient Functional diversity Functional traits Leaf elements Niche complementarity

Analysis Of Urban Planning Instruments in Comala,Colima,Mexico(1997-2009)from a Gender Perspective-A Secondary Publication

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journal of Architectural Research and Development 2024年第1期8卷 93-101页

作者： E.j.García Espíritu P.Chung Alonso I.BarajasÁvalos M.S.R.Covarrubias Ruesga M.P.ramírez Rivera National Technological Institute of Mexico Mayor Benito Juárez CP 03330Mexico CityMexico

This work is carried out based on the analysis of urban planning instruments,taking the gender perspective as a foundation.It arises from the inclusion of women in the participation of urban development,through an analysis of the gender gaps that have marked the history of women,the inequalities serve as a basis for carrying out this study.It highlights the challenges we face today as a society in the process of building citizen participation,where we must all be recognized and have equal opportunities within the territory in which we live.This article analyzes the extent to which the Municipal Urban Development Programs of the Mexican municipality of Comala,Colima,Mexico,consider the recommendations on gender and urbanism,established since the 1990s by international entities and applied transversally to urban planning policies.Considerable differences are found between women and men in terms of empowerment and participation in urban territorial planning instruments,mainly in the oldest instrument(1997).Significant progress is observed in the most recent document and is currently in force in the municipality of Comala(2009).

关键词： Planning instruments Gender perspective Urban planning

Influence of biomass burning on ozone levels in the Megalopolis of Central Mexico during the COVID-19 lockdown

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journal of Environmental Sciences 2024年第9期143卷 99-115页

作者： Victor Almanza Luis Gerardo Ruiz-Suárez Ricardo Torres-jardón Agustín García-Reynoso Iván Y.Hernández-Paniagua Institute for Atmospheric Sciences and Climate Change National Autonomous University of MexicoCoyoacan 04510Mexico CityMexico

The massive reductions in anthropogenic emissions resulting from the COVID-19 lockdown provided a unique opportunity to evaluate the effect of mitigation measures aiming to abate air pollution.In Mexico,the total lockdown period took place during the dry-hot season when biomass burning activity is enhanced.Here,we investigate the role of biomass burning emissions on regional ozone levels in the Megalopolis of Central Mexico.The studied period covers the lockdown phases 2 and 3,and the first month of the New Normal.We applied a factor separation technique and process analysis to estimate the pure and synergistic contributions of emission reductions under lockdown and that from biomass burning to daily ozone maximum concentrations in 7 metropolitan areas of different states in the Megalopolis.The results revealed that biomass burning plumes likely masked the effect of massive reductions from mobile emissions,impacted the PBL development during phase 3 and favored transition and mixed NO_(x)-limited and VOC-limited regional regimes.This contributed to increased ozone production in the middle to lower PBL by changing the regional background levels which potentially could bias high ozone production efficiency estimations.Given the Megalopolis contribution to economic and societal development at national scale,our study suggests that ozone mitigation measures during the dry-hot season targeting mainly mobile emissions will likely be offset by biomass burning plumes.A regional and synergic policy aiming to control biomass burning would help to reduce the occurrence of high ozone levels in Central Mexico with the co-benefit of tackling short-lived climate pollutants.

关键词： COVID-19 Mexico Megalopolis Ozone Factor Separation Process Analysis

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