The increasing demand for reducing vehicle weight in the automotive and aerospace industries has raised the need to develop improved structural aluminum-based alloys. Thus, horizontal solidification experiment with th...The increasing demand for reducing vehicle weight in the automotive and aerospace industries has raised the need to develop improved structural aluminum-based alloys. Thus, horizontal solidification experiment with the Al-7%Si-0.3%Mg（mass fraction） alloy was carried out. A water-cooled horizontal directional solidification device was developed and used. Microstructural characterization was carried out using traditional techniques of metallography, optical microscopy and SEM microscopy. The Thermo-Calc software was used to generate the solidification path of the investigated alloy with addition of 0.17% Fe（mass fraction）. The effects of the thermal parameters such as the growth rate（VL）, cooling rate（TC） and solidification local time（tSL） on the formation of the macrostructure and on the dendritic microstructure evolution were evaluated. A columnar to equiaxed transition（CET） was found for VL and TC values from 0.82 to 0.98 mm/s and from 1.71 to 2.55 ℃/s, respectively. The microstructure was characterized by the measurement of the primary and secondary dendrite arm spacings（λ1 and λ2, respectively）. Experimental laws of λ1 =f（VL, TC） and λ2 =f（tSL） were proposed. It is observed that the interdendritic region is composed of the following eutectic mixture： a（Al）＋Si＋p-Al8 Mg3 Fe Si6＋q-Mg2 Si.展开更多
As-cast samples of the Al-3wt.%Ni-lwt.%Bi alloy resulting from the horizontal directional solidification process were subjected to the micro-abrasive wear test.The effects of the solidification thermal and microstruct...As-cast samples of the Al-3wt.%Ni-lwt.%Bi alloy resulting from the horizontal directional solidification process were subjected to the micro-abrasive wear test.The effects of the solidification thermal and microstructural parameters,such as the growth and cooling rates and the cellular and primary dendritic spacings(VL and TR;λ1 and λc;respectively),were evaluated in the wear resistance of the investigated alloy.The tribological parameters analyzed were the wear volume and rate(Vw and Rw).The solidification experiments and the wear tests were carried out by means of a water-cooled horizontal directional solidification device and a rotary-fixed ball wear machine,respectively.The results show lower Vw and Rw values correspond to finer microstructures and the Vw dependence on λ1 is characterized by an experimental mathematical equation.A better distribution of Bi soft droplets and Al3Ni hard intermetallic particles is observed within the finer interdendritic region and,in consequence,the better wear resistance is achieved in as-cast samples with dendritic morphology rather than cellular morphology.A transition of wear mechanism from adhesive to abrasive is observed.展开更多
The Atlantic Forest is one of the largest and most biodiverse rainforests of South America but anthropogenic activities are drastically changing these landscapes.The invasion of alien or exotic species is one of the g...The Atlantic Forest is one of the largest and most biodiverse rainforests of South America but anthropogenic activities are drastically changing these landscapes.The invasion of alien or exotic species is one of the greatest threats to biodiversity.There are few studies of invasive species in tropical Brazilian ecosystems.This research examines growth and ecological aspects of Syzygium cumini and Clitoria fairchildiana,two invasive tree species in the Pedra Branca State Park,an Atlantic Forest remnant in southeastern Brazil.Both species were successfully dated,indicating an average age of 58 and 31 years,respectively.A positive relationship between growth and precipitation of the previous growing season suggests an ecological adaptive strategy,which could be facilitating their invasion into the environment.Cumulative growth diameter curves indicate slow and fast growth rates for S.cumini and C.fairchildiana,respectively.Growth release episodes detected in the tree rings indicate increased anthropogenic disturbances over the last 50 years.展开更多
Gas-liquid separation is a very common process in industrial plants,where often high Efficiency of Gas Separation(EGS)is demanded.In the upstream oil industry,gas separation is also crucial for the proper operation of...Gas-liquid separation is a very common process in industrial plants,where often high Efficiency of Gas Separation(EGS)is demanded.In the upstream oil industry,gas separation is also crucial for the proper operation of Electrical Submergible Pumps(ESP).Recent studies report the excellent performance of a gravitational separator known as Inverted-Shroud separator(IS-separator).Laboratory results indicate that this kind of separator can achieve total gas separation for a wide range of operation conditions under continuous two-phase flow.The original intent is to use the IS-separator for downhole gas separation in oil production wells.However,by account of its simple design and relatively compact size,it may be suitable for using in industrial plants.In this paper,we present the IS-separator in details,including geometry characteristics and phenomenology.The equipment performance is also discussed.In addition,the challenges related to the deep understanding of the gas separation process inside the IS-separator and the possible practical solutions are outlined.展开更多
Knowledge of the mechanisms that trigger infection-related encephalopathies is still very limited and cell therapies are one of the most promising alternatives for neurodegenerative diseases,and its application in inf...Knowledge of the mechanisms that trigger infection-related encephalopathies is still very limited and cell therapies are one of the most promising alternatives for neurodegenerative diseases,and its application in infectious diseases can be of great relevance.Mesenchymal stromal cells are cells with great immunomodulatory potential;therefore,their use in clinical and preclinical studies in a variety of diseases,including central nervous system diseases,increased in the last decade.Mesenchymal stromal cells can exert their beneficial effects through several mechanisms,such as direct cell contact,through surface receptors,and also through paracrine or endocrine mechanisms.The paracrine mechanism is widely accepted by the scientific community and involves the release of soluble factors,which include cytokines,chemokines and trophic factors,and extracellular vesicles.This mini review discusses mesenchymal stromal cells mechanisms of action in neurological disorders,the neuroinflammatory process that takes place in the brain as a result of peripheral inflammation and changes in the brain’s cellular scenario as a common factor in central nervous system diseases,and mesenchymal stromal cells therapy in encephalopathies.Mesenchymal stromal cells have been shown to act in neuroinflammation processes,leading to improved survival and mitigating behavioral damage.More recently,these cells have been tested in preclinical models of infectious diseases-associated encephalopathies(e.g.,cerebral malaria and sepsis associated encephalopathy)and have shown satisfactory results.展开更多
The increased demand of electronic devices promotes the development of advanced and more efficient energy storage devices, such as batteries. Lithium-ion batteries (LIBs) are the most studied battery systems due to th...The increased demand of electronic devices promotes the development of advanced and more efficient energy storage devices, such as batteries. Lithium-ion batteries (LIBs) are the most studied battery systems due to their high performance. Among the different battery components, the separator allows the control of lithium ion diffusion between the electrodes. To overcome some drawbacks of liquid electrolytes, including safety and environmental issues, solid polymer electrolytes (SPEs) are being developed. In this work, a UV photocurable polyurethane acrylate (PUA) resin has been blended with lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) up to 30 wt% LiTFSI content to reach a maximum ionic conductivity of 0.0032 mS/cm at room temperature and 0.09 mS/cm at 100 ℃. Those values allowed applying the developed materials as photocurable SPE in Swagelok type Li/C-LiFePO_(4) half-cells, reaching a battery discharge capacity value of 139 mAh.g^(−1) at C/30 rate. Those results, together with the theoretical studies of the discharge capacity at different C-rates and temperatures for batteries with LiTFSI/PUA SPE demonstrate the suitability of the developed photocurable SPE for LIB applications.展开更多
基金financial support provided by IFPA-Federal Institute of Education, Science and Technology of Pará, UFPA-Federal University of Pará, and CNPq-The Brazilian Research Council (Grants 472745/2013-1, 308784/2014-6 and 302846/2017-4)FAPESPA-Amazon Foundation of Support to Study and Research (Grants ICAAF 064/2016)CAPES-Coordination of Superior Level Staff Improvement, Brazil
文摘The increasing demand for reducing vehicle weight in the automotive and aerospace industries has raised the need to develop improved structural aluminum-based alloys. Thus, horizontal solidification experiment with the Al-7%Si-0.3%Mg（mass fraction） alloy was carried out. A water-cooled horizontal directional solidification device was developed and used. Microstructural characterization was carried out using traditional techniques of metallography, optical microscopy and SEM microscopy. The Thermo-Calc software was used to generate the solidification path of the investigated alloy with addition of 0.17% Fe（mass fraction）. The effects of the thermal parameters such as the growth rate（VL）, cooling rate（TC） and solidification local time（tSL） on the formation of the macrostructure and on the dendritic microstructure evolution were evaluated. A columnar to equiaxed transition（CET） was found for VL and TC values from 0.82 to 0.98 mm/s and from 1.71 to 2.55 ℃/s, respectively. The microstructure was characterized by the measurement of the primary and secondary dendrite arm spacings（λ1 and λ2, respectively）. Experimental laws of λ1 =f（VL, TC） and λ2 =f（tSL） were proposed. It is observed that the interdendritic region is composed of the following eutectic mixture： a（Al）＋Si＋p-Al8 Mg3 Fe Si6＋q-Mg2 Si.
基金financial support provided by IFPA-Federal Institute of Education, Science and Technology of Pará, UFPA-Federal University of Pará, and CNPq-The Brazilian Research Council (grants 302846/2017-4 and 400634/2016-3)CAPES-Coordenacao de Aperfeicoamento de Pessoal de Nível SuperiorBrasil-Finance Code 001
文摘As-cast samples of the Al-3wt.%Ni-lwt.%Bi alloy resulting from the horizontal directional solidification process were subjected to the micro-abrasive wear test.The effects of the solidification thermal and microstructural parameters,such as the growth and cooling rates and the cellular and primary dendritic spacings(VL and TR;λ1 and λc;respectively),were evaluated in the wear resistance of the investigated alloy.The tribological parameters analyzed were the wear volume and rate(Vw and Rw).The solidification experiments and the wear tests were carried out by means of a water-cooled horizontal directional solidification device and a rotary-fixed ball wear machine,respectively.The results show lower Vw and Rw values correspond to finer microstructures and the Vw dependence on λ1 is characterized by an experimental mathematical equation.A better distribution of Bi soft droplets and Al3Ni hard intermetallic particles is observed within the finer interdendritic region and,in consequence,the better wear resistance is achieved in as-cast samples with dendritic morphology rather than cellular morphology.A transition of wear mechanism from adhesive to abrasive is observed.
基金The work was partially supported by CAPES(Coordena玢o de Aperfei鏾amento de Pessoal de Nível Superior-Brasil-Finance Code 001).
文摘The Atlantic Forest is one of the largest and most biodiverse rainforests of South America but anthropogenic activities are drastically changing these landscapes.The invasion of alien or exotic species is one of the greatest threats to biodiversity.There are few studies of invasive species in tropical Brazilian ecosystems.This research examines growth and ecological aspects of Syzygium cumini and Clitoria fairchildiana,two invasive tree species in the Pedra Branca State Park,an Atlantic Forest remnant in southeastern Brazil.Both species were successfully dated,indicating an average age of 58 and 31 years,respectively.A positive relationship between growth and precipitation of the previous growing season suggests an ecological adaptive strategy,which could be facilitating their invasion into the environment.Cumulative growth diameter curves indicate slow and fast growth rates for S.cumini and C.fairchildiana,respectively.Growth release episodes detected in the tree rings indicate increased anthropogenic disturbances over the last 50 years.
基金The authors acknowledge ANP,Petrobras and CNPq(contracts 164211/2015-2,501443/2014-2 and 151317/2014-3)for the financial support.L.Enrique Ortiz Vidal is also grateful to FIPAI.
文摘Gas-liquid separation is a very common process in industrial plants,where often high Efficiency of Gas Separation(EGS)is demanded.In the upstream oil industry,gas separation is also crucial for the proper operation of Electrical Submergible Pumps(ESP).Recent studies report the excellent performance of a gravitational separator known as Inverted-Shroud separator(IS-separator).Laboratory results indicate that this kind of separator can achieve total gas separation for a wide range of operation conditions under continuous two-phase flow.The original intent is to use the IS-separator for downhole gas separation in oil production wells.However,by account of its simple design and relatively compact size,it may be suitable for using in industrial plants.In this paper,we present the IS-separator in details,including geometry characteristics and phenomenology.The equipment performance is also discussed.In addition,the challenges related to the deep understanding of the gas separation process inside the IS-separator and the possible practical solutions are outlined.
基金This work was supported by the Brazilian Council for Scientific and Technological Development(grant number 406110/2016-6)Inova Fiocruz/Oswaldo Cruz Foundation(grant number VPPCB-008-FIO-18-2-56-30,to TMG).
文摘Knowledge of the mechanisms that trigger infection-related encephalopathies is still very limited and cell therapies are one of the most promising alternatives for neurodegenerative diseases,and its application in infectious diseases can be of great relevance.Mesenchymal stromal cells are cells with great immunomodulatory potential;therefore,their use in clinical and preclinical studies in a variety of diseases,including central nervous system diseases,increased in the last decade.Mesenchymal stromal cells can exert their beneficial effects through several mechanisms,such as direct cell contact,through surface receptors,and also through paracrine or endocrine mechanisms.The paracrine mechanism is widely accepted by the scientific community and involves the release of soluble factors,which include cytokines,chemokines and trophic factors,and extracellular vesicles.This mini review discusses mesenchymal stromal cells mechanisms of action in neurological disorders,the neuroinflammatory process that takes place in the brain as a result of peripheral inflammation and changes in the brain’s cellular scenario as a common factor in central nervous system diseases,and mesenchymal stromal cells therapy in encephalopathies.Mesenchymal stromal cells have been shown to act in neuroinflammation processes,leading to improved survival and mitigating behavioral damage.More recently,these cells have been tested in preclinical models of infectious diseases-associated encephalopathies(e.g.,cerebral malaria and sepsis associated encephalopathy)and have shown satisfactory results.
基金Work supported by the Portuguese national funds(PIDDAC),through the Portuguese Foundation for Science and Technology(FCT)and FCT/MCTES:projects UID/FIS/04650/2020.UID/QUI/0686/2020,UID/CTM/50025/2020,UIDB/05549/2020,PTDC/FIS-MAC/28157/2017Grants SFRH/BD/140842/2018(J.C.B.),CEECIND/00833/2017(R.G.)and SFRH/BPD/112547/2015(C.M.C.).Financial support from the Basque Government Industry Departments under the ELKARTEK and HAZITEK programs is also acknowledged.
文摘The increased demand of electronic devices promotes the development of advanced and more efficient energy storage devices, such as batteries. Lithium-ion batteries (LIBs) are the most studied battery systems due to their high performance. Among the different battery components, the separator allows the control of lithium ion diffusion between the electrodes. To overcome some drawbacks of liquid electrolytes, including safety and environmental issues, solid polymer electrolytes (SPEs) are being developed. In this work, a UV photocurable polyurethane acrylate (PUA) resin has been blended with lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) up to 30 wt% LiTFSI content to reach a maximum ionic conductivity of 0.0032 mS/cm at room temperature and 0.09 mS/cm at 100 ℃. Those values allowed applying the developed materials as photocurable SPE in Swagelok type Li/C-LiFePO_(4) half-cells, reaching a battery discharge capacity value of 139 mAh.g^(−1) at C/30 rate. Those results, together with the theoretical studies of the discharge capacity at different C-rates and temperatures for batteries with LiTFSI/PUA SPE demonstrate the suitability of the developed photocurable SPE for LIB applications.
