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Effect of thermo-mechanical conditions during constrained friction processing on the particle refinement of AM50 Mg-alloy phases

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Journal of Magnesium and Alloys 2024年第6期12卷 2298-2311页

作者： Camila Caroline de Castro Andrémartins Neves Benjamin Klusemann Helmholtz-Zentrum Hereon Institute of Material and Process DesignSolid-State Materials Processing21502 GeesthachtGermany Helmholtz-Zentrum Hereon Institute of Hydrogen TechnologySystem Design for Mobility21502 GeesthachtGermany Helmut Schmidt University/University of the German federal Armed forces Hamburg Department of Mechanical and Civil Engineering22043 HamburgGermany Leuphana University Lüneburg Institute for Production Technology and Systems21335 LüneburgGermany

Constrained friction Processing(CfP)is a novel solid-state processing technique suitable for lightweight materials,such Mg-and *** technique enables grain size refinement to fine or even ultrafine *** this study,the effect of CfP on the microstructural refinement of AM50 rods is investigated in terms of particle size and morphology of the eutectic and secondary phases originally present in the base material,in particular the eutecticβ-Mg_(17)Al_(12)and Al-Mn *** that purpose,as-cast and solution heat-treated base material and processed samples were *** Al8Mn5 intermetallic phase was identified as the main secondary phase present in all samples before and after the processing.A notorious refinement of these particles was observed,starting from particles with an average equivalent length of a few micrometers to around 560 nm after the *** refinement of the secondary phase refinement is attributed to a mechanism analogous to the attrition comminution,where the combination of temperature increase and shearing of the material enables the continuous breaking of the brittle intermetallic particles into smaller *** for the eutectic phase,the results indicate the presence of the partially divorcedβ-Mg_(17)Al_(12)particles exclusively in the as-cast base material,indicating that no further phase transformations regarding the eutectic phase,such as dynamic precipitation,occurred after the *** the case of the processed as-cast material analyzed after the CfP,the thermal energy generated during the processing led to temperature values above the solvus limit of the eutectic phase,which associated with the mechanical breakage of the particles,enabled the complete dissolution of this ***,CfP was successfully demonstrated to promote an extensive microstructure refinement in multiple aspects,in terms of grain sizes of theα-Mg phase and presence and morphology of the Al-Mn and eutecticβ-Mg_(17)Al_(12).

关键词： Constrained friction processing AM50 refill friction stir spot welding Extrusion β-Mg_(17)Al_(12) Al-Mn phases

Spatiotemporal dynamics in butterfly hybrid zones

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Insect Science 2024年第2期31卷 328-353页

作者： Ananda r.Pereira martins Natalie B.Warren W.Owen McMillan rowan D.H.Barrett redpath Museum McGill University859 Sherbrooke Street WestMontrealQuebecCanada Smithsonian Tropical researchInstitute GamboaPanama CityPanama

Evaluating whether hybrid zones are stable or mobile can provide novelinsights for evolution and conservation biology. Butterflies exhibit high sensitivity to envi-ronmental changes and represent an important model system for the study of hybrid zoneorigins and maintenance. Here, we review the literature exploring butterfly hybrid zones,with a special focus on their spatiotemporal dynamics and the potential mechanisms thatcould lead to their movement or stability. We then compare different lines of evidenceused to investigate hybrid zone dynamics and discuss the strengths and weaknesses ofeach approach. Our goal with this review is to reveal general conditions associated withthe stability or mobility of butterfly hybrid zones by synthesizing evidence obtained us-ing different types of data sampled across multiple regions and spatial scales. finally, wediscuss spatiotemporal dynamics in the context of a speciation/divergence continuum, therelevance of hybrid zones for conservation biology, and recommend key topics for futureinvestigation.

关键词： butterflies human impacts hybrid zones movement spatiotemporaldynamics stability

rheological and stability analysis of cement pastes incorporating silica-based wastes

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Particuology 2024年第6期89卷 144-152页

作者： Julia da rosa martins Janaíde Cavalcante rocha Dachamir Hotza Luciano Senff Graduate Program in Materials Science and Engineering(PPGMAT) Federal University of Santa Catarina(UFSC)Florianópolis88040-900SCBrazil Graduate Program in Civil Engineering(PPGEC) Federal University of Santa Catarina(UFSC)Florianópolis88040-900SCBrazil Graduate Program in Chemical Engineering(POSENQ) Federal University of Santa Catarina(UFSC)Florianópolis88040-900SCBrazil Department of Mobility Engineering Federal University of Santa Catarina(UFSC)Joinville89219-600SCBrazil

This study investigates the influence of waste characteristics,especially zeta potential,on the properties of cement pastes and *** focus is to evaluate the impact of the zeta potential of cement particles and waste materials on the sedimentation speed,rheology,and hardening time of stabilized cement *** Cement II f 40,retarder additive,silica,and fly ash were used in the *** pastes were prepared,and during the stabilization period,their rheological properties and pH were *** zeta potential and sedimentation speed of the cement and waste particles were measured at the pH that the pastes presented during the entire stabilization *** the stabilization period,the pastes were subjected to the hardening time *** zeta potential analyses revealed diverse values for the different powder types,with the cement particles exhibiting a zeta potential of−3.0 mV,the silica particles exhibiting−10.5 mV,and the fly ash particles exhibiting−20.3 *** influence of the high zeta potential modulus was observed on the sedimentation speed,with the solution containing fly ash exhibiting a speed of 40.01μm/s,whereas the solution containing only cement exhibited a speed of 99.38μm/*** the pastes,the results indicate that the presence of fly ash particles with a significantly negative zeta potential led to a 16%reduction in hardening time compared to particles with a lower modulus of zeta *** tests showed that the inclusion of fly ash particles prevented the formation of *** the zeta potential influenced agglomerate formation and hardening time,it was found to have no effect on yield stress or viscosity.

关键词： Wastes Zeta potential Setting time rheometry

recent advancements in continuously scalable conversion-ratio switched-capacitor converter

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Journal of Semiconductors 2024年第4期45卷 8-11页

作者： Mo Huang Yuanfei Wang rui P.martins Yan Lu State Key Laboratory of Analog and Mixed-Signal VLSI Institute of MicroelectronicsUniversity of MacaoMacaoChina

Switched-capacitor(SC)DC-DC converter[1]is an impor-tant alternative to inductive DC-DC converter,in terms of removing the bulky power ***,it is widely used in low-profile,low-power applications,such as the internet of things(IoT)sensor nodes and energy harvesting[2].Mean-while,considering that capacitor has a much higher energy density than inductor,high-power applications.

关键词： converter switched removing

A new approach to pedestal differentiation for soil loss estimation-a case study from a burnt area in north-central Portugal

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Journal of forestry research 2024年第3期35卷 45-54页

作者： frank G.A.Verheijen Martinho A.S.martins Sergio A.Prats Jan J.Keizer Centre for Environmental and Marine Studies(CESAM) Department Environment and PlanningUniversity of Aveiro3810-193 AveiroPortugal Mediterranean Institute for Agriculture Environment and Development(MED-CHANGE)Institute for Advanced Studies and ResearchUniversity of EvoraPolo da MitraAp.947006-554 EvoraPortugal GeoBiociencias Geotecnologias E Geoengenharias(GEOBIOTEC)Department Environment and PlanningUniversity of Aveiro3810-193 AveiroPortugal

Soil pedestals have long been used as qualitative indicators of soil splash *** rangelands,plant-capped pedestals,generally grass tussocks,have also been used to quantitatively estimate soil loss since the first half of the twentieth *** agricultural lands,forests,and bad-lands,stone-capped pedestals have been used as qualitative and semi-quantitative indicators of active,'extreme'*** work has been reported on using capstone pedestal data for quantifying soil *** postulate that three distinct capstone pedestal types may be present in any given location and that a detailed analysis of a pedestal height histogram may be used to recognize their *** analysis can subsequently inform if soil loss can be reliably estimated and if so,which of the existing methods using pedestal height data will provide more accurate *** three proposed capstone pedestal types are:(1)neo-pedestals formed underneath surface stones exposed by(partial)removal of the soil surface cover;(2)endo-pedestals formed underneath stones that were buried in the soil but have been exposed by erosion;and(3)phoenix-pedestals formed underneath stones from collapsed *** the pedestal height histogram of any given location,a skew to smaller heights may indicate the existence of endo-and/or phoenix-pedestals,which may be revealed as a bi-(or tri)modal distribution when using a smaller bin *** concept was applied to a case study where soil loss had been monitored for control plots and mulched plots during a 5-year period following wildfire in a eucalypt *** measured pedestal heights and used methods to quantitatively assess soil loss from soil pedestal data in the available *** pedestal data at the end of the 5-year period under or overestimated soil loss in the control treatment,with results ranging from 60 to 115%of measured soil loss,depending on the *** is postulated that phoenix-and endo-pedestals may be a driving fact

关键词： Soil pedestals Mulch Wildfire Soil erosion Char

Colorectal cancer screening:A review of current knowledge and progress in research

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World Journal of Gastrointestinal Oncology 2024年第4期16卷 1119-1133页

作者： Sara ramos Lopes Claudio martins Inês Costa Santos Madalena Teixeira Élia Gamito Ana Luisa Alves Department of Gastroenterology Centro Hospitalar de SetúbalSetúbal 2910-446Portugal

Colorectal cancer(CrC)is one of the most prevalent malignancies worldwide,being the third most commonly diagnosed malignancy and the second leading cause of cancer-related deaths *** the progress in screening,early diagnosis,and treatment,approximately 20%-25%of CrC patients still present with metastatic disease at the time of their initial ***,the burden of disease is still expected to increase,especially in individuals younger than 50 years old,among whom early-onset CrC incidence has been *** and early detection are pivotal to improve CrC-related *** is well established that CrC screening not only reduces incidence,but also decreases deaths from *** screening strategies have proven effective in decreasing both CrC incidence and mortality,though variations in efficacy have been reported across the ***,uncertainties persist regarding the optimal screening method,age intervals and ***,adherence to CrC screening remains globally *** recent years,emerging technologies,notably artificial intelligence,and non-invasive biomarkers,have been developed to overcome these ***,controversy exists over the actual impact of some of the new discoveries on CrC-related outcomes and how to effectively integrate them into daily *** this review,we aim to cover the current evidence surrounding CrC *** will further critically assess novel approaches under investigation,in an effort to differentiate promising inno-vations from mere novelties.

关键词： Colorectal cancer Screening review Oncology Artificial intelligence

Smart contract applications in the built environment: How prepared are Nigerian construction stakeholders?

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frontiers of Engineering Management 2024年第1期11卷 50-61页

作者： Andrew EBEKOZIEN Clinton AIGBAVBOA Samuel Adeniyi ADEKUNLE Mohamad Shaharudin SAMSUrIJAN John ALIU Bernard martins ArTHUr-AIDOO Godpower Chinyeru AMADI Department of Construction Management and Quantity Surveying University of JohannesburgJohannesburg 2006South Africa School of Social Sciences Universiti Sains MalaysiaGelugor11800 USM PenangMalaysia Department of Quantity Surveying Auchi PolytechnicAuchiNigeria Institute for resilient Infrastructure Systems College of EngineeringUniversity of GeorgiaAthensGA 30602USA Department of Building Technology Faculty of Built EnvironmentAccra Technical UniversityAccraGhana Nigerian Institute of Management Port HarcourtNigeria

Studies have demonstrated that advanced technology,such as smart contract applications,can enhance both pre-and post-contract administration within the built environment *** contract technology,exemplifying blockchain technologies,has the potential to improve transparency,trust,and the security of data transactions within this ***,there is a dearth of academic literature concerning smart contract applications within the construction industries of developing countries,with a specific focus on ***,this study seeks to explore the relevance of smart contract technology and address the challenges impeding its adoption,offering strategies to mitigate the obstacles faced by smart contract *** investigate the stakeholders,this research conducted 14 virtual interview sessions to achieve data *** interviewees encompassed project management practitioners,senior management personnel from construction companies,experts in construction dispute resolution,professionals in construction software,and representatives from government construction *** data obtained from these interviews underwent thorough analysis employing a thematic *** study duly recognizes the significance of smart contract applications within the *** the 12 identified barriers,issues such as identity theft and data leakage,communication and synchronization challenges,high computational expenses,lack of driving impetus,excessive electricity consumption,intricate implementation processes,absence of a universally applicable legal framework,and the lack of a localized legal framework were recurrent impediments affecting the adoption of smart contract applications within the *** study also delves into comprehensive measures to mitigate these *** conclusion,this study critically evaluates the relevance of smart contract applications within the built environment,with a specific focus on promoting their *** may serve

关键词： built environment industry digitalization Nigeria smart contract technological revolution

Determining the effective elastic thickness through cross-correlation between isostatic disturbances

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Geodesy and Geodynamics 2024年第3期15卷 241-251页

作者： Nelson ribeiro-filho Cristiano Mendel martins raissa Moraes Baldez Ivaldevingles rodrigues de Souza Júnior franck Eitel Kemgang Ghomsi Instituto federal do Pará(IfPA) AltamiraParáBrazil Universidade federal do Pará(UfPA) BelemParáBrazil Nansen-Tutu Center for Marine Environmental research Department of OceanographyUniversity of Cape TownSouth Africa Geodesy research Laboratory National Institute of CartographyYaoundeCameroon

The elastic thickness parameter was estimated using the mobile correlation technique between the observed isostatic disturbance and the gravity disturbance calculated through direct gravimetric modeling. We computed the vertical flexure value of the crust for a specific elastic thickness using a given topographic dataset. The gravity disturbance due to the topography was determined after the calculation. A grid of values for the elastic thickness parameter was generated. Then, a moving correlation was performed between the observed gravity data(representing actual surface data) and the calculated data from the forward modeling. The optimum elastic thickness of the particular point corresponded to the highest correlation coefficient. The methodology was tested on synthetic data and showed that the synthetic depth closely matched the original depth, including the elastic thickness value. To validate the results, the described procedure was applied to a real dataset from the Barreirinhas Basin, situated in the northeastern region of Brazil. The results show that the obtained crustal depth is highly correlated with the depth from known models. Additionally, we noted that the elastic thickness behaves as expected, decreasing from the continent towards the ocean. Based on the results, this method has the potential to be employed as a direct estimate of crustal depth and elastic thickness for any region.

关键词： Isostasy Elastic thickness Isostatic disturbance Moho depth Cross-correlation

ENSO impacts on litter stocks and water holding capacity in secondary forests in eastern Amazonia

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Journal of forestry research 2024年第1期35卷 83-89页

作者： Julia Isabella de Matos rodrigues Walmer Bruno rocha martins Victor Pereira de Oliveira Myriam Suelen da Silva Wanzerley Hélio Brito dos Santos Júnior francisco de Assis Oliveira Graduate Program in forestry Sciences Av.Presidente Tancredo Neves2501BelémPará66077-530Brazil federal rural University of Amazonia Av.Presidente Tancredo Neves2501BelémPará66077-530Brazil federal rural University of Amazonia Tv.Pau-AmareloCapitão PoçoPará68650-000Brazil National Institute of Amazonia research Av.Constelação Cruzeiro do SulManausAmazonas 69060-062Brazil

Among the impacts of climate change,there is the intensification of phenomena such as the El Niño South-ern Oscillation(ENSO)responsible for El Niño and La Niñ***,understanding their effects on the functional pro-cesses of forests is ***,this study evaluated the effects of ENSO on litter stock and water holding capac-ity(WHC)in a successional forest in eastern *** occurred in periods with the most rainfall in El Niño(2019)and least in La Niña(2021)*** permanent plots were used to sample *** effects were evident for WHC,higher during El Niñ***,this influence was not clear for litter,as only in the rainy season effects were *** was a positive correlation of WHC with precipitation and humidity,while litter stocks were negatively correlated with temperature and wind *** the subject of this study requires long-term assessments,preliminary results suggests that,depending on the intensity of ENSO,forest functional processes can be strongly impacted and *** conclusion reinforces warnings by the scientific community about the impacts of climate change on the maintenance of litter stocks,decomposition and,consequently,the biogeochemical cycle and essential ecosystem services for the maintenance of Amazonia *** need to develop long-term research to understand the effects of climatic change on litter stocks and water holding capacity is highlighted,especially in Amazonia.

关键词： Seasonality Climate change Succession ecosystem Biogeochemical cycle Amazonia biodiversity