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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 *** Al_(8)Mn_(5) 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

Structure of a Semideciduous Seasonal Forest in the National Forest of Ipanema,Brazil:Contributing to the Floristic Knowledge of a Poorly Studied Protected Area

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Research in Ecology 2022年第3期4卷 10-19页

作者： Vinícius Londe Felipe Segala Ferreira fernando roberto martins Independent Researcher Lisbon1070-118Portugal Graduate Course in Plant Biology University of CampinasCampinasSão Paulo13083-970Brazil Plant Biology Department Institute of BiologyUniversity of CampinasCampinas13083-970Brazil

Studies on composition and structure generate crucial information for characterizing plant communities and planning conservation *** are still substantial knowledge gaps in Brazilian protected areas,preventing design programs to mitigate biodiversity *** is the case of the National Forest of Ipanema(Ipanema NAFO)in São Paulo state,Brazil,where plant diversity remains *** help fill this gap,in 1-ha of a seasonal semideciduous forest(SSF)stand on the Araçoiaba hill,the authors sampled all woody stems with dbh≥5 cm in a total of 103 dead and 1,301 living plants representing 65 species,57 genera,and 31 *** number of species and families was lower than old-growth SSF and,together with the land-use history,which suggests the community is a secondary *** initial species Guazuma ulmifolia,Machaerium stipitatum,Croton floribundus,and Aloysia virgata totalized 50%of the living stems,whereas 37%of the other species summed up only 1.8%.The high abundance of these initial species and the presence of the climax species Cariniana legalis,Holocayx balansae,Myroxylon peruiferum,Zanthoxylum caribaeum and others indicate that the community is in an intermediate to advanced successional *** species are considered vulnerable to extinction and 27 of least *** NAFO is an important conservation unit,sheltering some plants vulnerable to extinction and others locally *** study adds to other few studies about the flora of Ipanema NAFO,helping to estimate its biodiversity and planning conservation ***,it is a source for defining reference values for ecological restoration in the Atlantic forest.

关键词： Community structure Floresta Nacional de Ipanema Atlantic forest Floristic inventory Vulnerable species

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

Impact Containment Barriers with Geotextile Tubes

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Journal of Geoscience and Environment Protection 2024年第5期12卷 325-344页

作者： Flávio da Silva Ornelas Luís fernando martins Ribeiro Rafael Cerqueira Silva Instituto Federal de Educaç &#227o Ci&#234ncia e Tecnologia&#8212IFTO Palmas Brasil Departamento de Engenharia Civil e Ambiental Programa de p&#243s gradua&#231&#227o em Geotecnia Universidade de Bras&#237lia&#8212UnB/Campus Universit&#225rio Darcy Ribeiro Bras&#237lia Brasil

Recently, tragic tailings dam collapses in Brazil have caused deaths and major destruction and the need to develop technologies capable of preventing damage to people and the environment. Brazilian tailings dams are in a situation of uncertainty due to new legislation that even requires decommissioning, an activity that involves many problems and where the risk of failure is the main one. An impact containment structure downstream of these dams can be effective and geotextile tubes, in a new approach, have emerged as an option with advantages in terms of execution, costs and safety. The technology is versatile and can bring many benefits such as the reuse of tailings or filling with low-energy or reused materials. In this research, geotextile tubes were tested as free containment barriers, experiencing impacts in reduced models. The safety factor for the stability of the structure was constructed using an equation which is the ratio between the self-weight of the barrier structure and its coefficient of static friction and the impact pressure, where the data showed an adequate correlation which suggests the viability of mitigating risks.

关键词： Geotextile Tube Debris Flow Barriers Impact Mining

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

How far have we come?Review of main public policies to reduce landslide impacts in Brazil

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Journal of Mountain Science 2024年第9期21卷 2891-2904页

作者： Bianca Carvalho VIEIRA Tiago Damas martins Telma Mendes da SILVA JoséEduardo BONINI Department of Geography University of São PauloAvenida Professor Lineu Prestes 05508-000Brazil Cities Institute Federal University of São PauloAvenida Jacu-Pêssego 08260-001Brazil Department of Geography Federal University of Rio de JaneiroAvenida Athos da Silveira Ramos 21941-916Brazil

During the rainy season in Brazil,landslides can have catastrophic consequences,including loss of life,damage to urban infrastructure and significant economic ***,more than eight million people in Brazil live in disaster-prone *** objective of this article is to present a chronological review of the principal policies and programmes at the national,state,and municipal levels,with an emphasis on their key actions aimed at mitigating the impact of disasters related to natural hazards,particularly *** analysis was based on official records of public policies from the national,state,and municipal *** results show that several initiatives were initially developed at the local and regional ***,it was not until the late 1980s that a comprehensive organisation of civil protection at the national level emerged as a response *** is possible to highlight three phases(understanding,coexistence,and prevention)of institutional action focused on risk management in the face of *** the growing knowledge of risk scenarios,disasters continue to occur in Brazil on an annual basis,revealing several obstacles to reducing their impact,particularly given the social and economic disparities between Brazilian regions and the applicability of public policies that must overcome the limitations of each municipality.

关键词： Disasters Risk Mitigation Prevention Legislation Civil Defense Natural Hazards

Real-world clinical efficacy of tofacitinib in moderate-to-severe ulcerative colitis

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World Journal of Gastroenterology 2024年第34期30卷 3929-3931页

作者： Sara R Lopes Claudio martins Madalena Teixeira David Tomás Department of Gastroenterology Unidade Local de Saúde da Arrábida-Hospital de São BernardoSetúbal 2910-446Portugal

Tofacitinib is an oral small-molecule Janus kinase(JAK)inhibitor that preferentially inhibits JAK1 and *** efficacy in inducing and maintaining remission in ulcerative colitis(UC)as well as its safety profile has been demonstrated in multicenter,randomized,double-blind,placebo-controlled ***,real-world studies evaluating the effectiveness and adverse effects of tofacitinib have been conducted,affirming its clinical efficacy in moderate-to-severe UC.

关键词： Ulcerative colitis Tofacitinib Real-world studies Inflammatory bowel disease Janus kinase inhibitor

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