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Remote Teaching of Experimental Chemistry in Developing Countries

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Journal of Chemistry and Chemical Engineering 2020年第3期14卷 97-104页

作者： Flores Helio santos elvira Lejarazo Eva Aluminate Network Group Data Science DepartmentHyperion House(First Floor)the OaksFordham RoadNewmarketSuffolkCB87XNUK Department of Organic Chemistry Faculty of ChemistryPostgraduate Studies UnitsCircuit Exterior S/NUniversity CityCP 04510CoyoacánMexico CityMexico

During the ongoing 2020 CoVid-19 crisis,the use of remote meeting technologies such as Zoom™,Microsoft Teams™and Google Meetings™has been paramount to theoretical teaching in a safe socially distanced ***,several problems arise when there is a need for an experimental *** paper looks at one of the possible solutions,including how to best separate the students,how to minimize close interactions and how a mixed environment of remote/presential teaching is required,minimizing the amount of extra materials,resources and protection equipment required,such that developing countries can quickly adopt this method,without the purchase of any external equipment.

关键词： CoVid-19 experimental chemistry remote education education Zoom laboratory social distancing.

Saturated anisotropic hydraulic conductivity of a compacted lateritic soil

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第5期10卷 986-991页

作者： Roberto Aguiar dos santos Edmundo Rogerio Esquivel Varzea Grande Institute of Engineering Federal University of Mato Grosso Cuiaba Mato Grosso Brazil Sao Carlos School of Engineering University of Sao Paulo Sao Carlos Sao Paulo Brazil

This study focuses on the saturated anisotropic hydraulic conductivity of a compacted lateritic clayey sandy soil. The effects of the molding water content and the confining stress on the anisotropic hydraulic conductivity are investigated. The hydraulic conductivity is measured with a flexible-wall permeameter. Samples are dynamically compacted into the three compaction states of a standard Proctor compaction curve： the dry branch, optimum water content and wet branch. Depending on the molding water content and confining stress, the hydraulic conductivity may increase or decrease. In addition, the results indicate that, when the samples are compacted to the optimum water content, lower hydraulic conductivity is obtained, except at a confining stress equal to 50 kPa. The increase of the confining stress decreases the hydraulic conductivity for each of the evaluated compaction states. In the wet branch, horizontal hy- draulic conductivity is about 8 times higher than the vertical value. The anisotropic hydraulic conduc- tivities of the dry and wet branches decrease when the confining stress increases, and the opposite is observed in the optimum water content state.

关键词： Hydraulic conductivity Anisotropic behavior Lateritic soil Tropical soil Compacted soil

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Fluorescent probes for the detection of reactive oxygen species in human spermatozoa

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Asian Journal of Andrology 2020年第5期22卷 465-471页

作者： Sara Escada-Rebelo Francisca G Mora Ana P Sousa Teresa Almeida-santos Artur Paiva Joao Ramalho-santos phD Programme in Experimental Biology and Biomedicine CNC-Center for Neuroscience and Cell BiologyUniversity of CoimbraCoimbra 3004-504Portugal Biology of Reproduction and Stem Cell Group CNC-Center for Neuroscience and Cell BiologyUniversity of CoimbraCoimbra 3004-504Portugal IIIUC-Institute for Interdisciplinary Research Casa Costa AlemaoUniversity of CoimbraCoimbra 3030-789Portugal Reproductive Medicine Unit University Hospitals of CoimbraCoimbra 3004-561Portugal Faculty of Medicine University of CoimbraCoimbra 3000-370Portugal Clinical Pathology Unit University Hospitals of CoimbraCoimbra 3004-561Portugal Department of Life Sciences University of CoimbraCoimbra 3000-456Portugal

Reactive oxygen species(ROS)production is a by-product of mitochondrial activity and is necessary for the acquisition of the capacitated state,a requirement for functional ***,an increase in oxidative stress,due to an abnormal production of ROS,has been shown to be related to loss of sperm function,highlighting the importance of an accurate detection of sperm ROS,given the specific nature of this *** this work,we tested a variety of commercially available fluorescent probes to detect ROS and reactive nitrogen species(RNS)in human sperm,to define their *** both flow cytometry(FC)and fluorescence microscopy(FM),we confirmed that MitoSOX™Red and dihydroethidium(DHE)detect superoxide anion(as determined using antimycin A as a positive control),while DAF-2A detects reactive nitrogen species(namely,nitric oxide).For the first time,we also report that RedoxSensor™Red CC-1,CellROX®Orange Reagent,and MitoPYl seem to be mostly sensitive to hydrogen peroxide,but not ***,mean fluorescence intensity(and not percentage of labeled cells)is the main parameter that can be reproducibly monitored using this type of methodology.

关键词： flow cytometry fluorescent probes human spermatozoa oxidative stress reactive oxygen species

Ultrafast laser-driven topological spin textures on a 2D magnet

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npj Computational Materials 2022年第1期8卷 1630-1635页

作者： Mara Strungaru Mathias Augustin Elton J.G.santos Institute for Condensed Matter Physics and Complex Systems School of Physics and AstronomyThe University of EdinburghEdinburghEH93FDUK Donostia International Physics Center(DIPC) 20018Donostia-San SebastiánBasque CountrySpain Higgs Centre for Theoretical Physics The University of EdinburghEdinburghEH93FDUK

Ultrafast laser excitations provide an efficient and low-power consumption alternative since different magnetic properties and topological spin states can be triggered and manipulated at the femtosecond(fs)***,it is largely unknown whether laser excitations already used in data information platforms can manipulate the magnetic properties of recently discovered two-dimensional(2D)van der Waals(vdW)*** we show that ultrashort laser pulses(30−85 fs)can not only manipulate magnetic domains of 2D-XY CrCl_(3)ferromagnets,but also induce the formation and control of topological nontrivial meron and antimeron spin *** observed that these spin quasiparticles are created within~100 ps after the excitation displaying rich dynamics through motion,collision and annihilation with emission of spin waves throughout the *** findings highlight substantial opportunities of using photonic driving forces for the exploration of spin textures on 2D magnetic materials towards magneto-optical topological applications.

关键词： laser excitation topological

Exploring spatial relationships between stream channel features,water depths and flow velocities during flash floods using HEC-GeoRAS and Geographic Information Systems

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Journal of Geographical Sciences 2022年第4期32卷 757-782页

作者： Miguel LEAL Eusébio REIS Pedro Pinto santos Centre of Geographical Studies and Associated Laboratory TERRA Institute of Geography and Spatial PlanningUniversidade de Lisboa1600-276 LisbonPortugal Forest Research Centre and Associated Laboratory TERRA School of AgricultureUniversidade de LisboaTapada da Ajuda1349-017 LisbonPortugal

Water depths and flow velocities decisively influence the damage caused by flash *** Information System(GIS)is a powerful and useful tool,allowing the spatial analysis of results obtained by hydraulic modelling,namely from the HEC-RAS/HEC-GeoRAS *** GIS spatial analysis performed in this study seeks to explain and quantify the spatial relationships between the stream channel features and flow components during flash flood *** these relationships are generically known,there are few studies exploring this subject in different geographic contexts.A 1D hydraulic model was applied in a small watershed in Portugal,providing good results in the definition of floodable areas,water depths and longitudinal *** direct relationship was found between water depths and velocities in the floodable areas;however,negative strong correlations were found between the two flow components along the stream *** slope,channel and flood width,and roughness prove to be highly relevant on the longitudinal variations of water depths and velocities and on the location of maximum *** peak discharges and return periods(R;)can change the relationships between water depths and velocities at the same *** can be improved with more accurate elevation data for stream channels and floodplains.

关键词： flash floods water depth flow velocity geographic information systems(GIS) spatial analysis

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Influence of a non-rotating shoulder on heat generation,microstructure and mechanical properties of dissimilar AA2024/AA7050 FSW joints

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Journal of Materials Science & Technology 2018年第1期34卷 119-127页

作者： Alessandro Barbini Jan Carstensen Jorge F.dos santos Helmholtz-Zentrum Geesthacht Institute of Materials Research Materials Mechanics Solid-State Joining Processes (WMP)

Friction stir welding （FSW） and stationary shoulder friction stir welding （SSFSW） were carried out for the butt joining of dissimilar AA2024-T3 and AA7050-T7651 aluminium alloys with thicknesses of 2 mm. A comparison between the two processes was performed by varying the welding speed while keeping the rotational speed constant, Through the analysis of the force and torque produced during welding and a simple analytical model, it was possible to show that in SSFSW there is more effective coupling with the tool and the heat produced is more efficiently distributed. This process decreases both the welding area and the diffusion at the interface of the two alloys compared with FSW. The minimum microhardness occurred at the advancing side （AS） at the interface between the thermo-mechanically affected zone （TMAZ） and the stir zone （SZ） in both processes, although the decrease was more gradual in SSFSW. This interface is also where all specimens failed for both welding technologies. An increase in tensile strength was measured in SSFSW compared with standard FSW. Furthermore, it was possible to establish the mechanical performance of the material in the fracture zone using digital image correlation.

关键词： Stationary shoulder friction stir welding Friction stir welding Dissimilar welded joints Process analysis Microstructure analysis Mechanical behaviour

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Evaluation and modeling of runoff and sediment yield for different land covers under simulated rain in a semiarid region of Brazil

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International Journal of Sediment Research 2018年第2期33卷 117-125页

作者： Richarde Marques da Silva Celso Augusto Guimares santos José Yure Gomes dos santos Department of Geosaences Federal University of Paraíba Department of Civil and Environmental Engineering Federal University of Paraíba Federal University of Western Bahia Center for Humanities

This paper quantifies the runoff and sediment yield for four different land covers in a semiarid region of Brazil. The WESP model, a distributed, event-oriented runoff-erosion model, was applied and its physical parameters, NSand KR, were adjusted based on observed runoff and sediment yield data using simulated rainfall with an average intensity of 53 mm h-1. The sediment yield obtained was 53.02 kg ha-1(caatinga vegetation), 231.96 kg ha-1(bare soil), 309.75 kg ha-1(beans), and 847.38 kg ha-1(corn). The results showed that caatinga cover yields the lowest erosion and runoff when compared to the other *** results also show that the sediment yield and runoff values simulated with NS, KI, and KR parameters were well calibrated, within acceptable deviations. The caatinga vegetation was more effective in protecting the soil, when compared to the other types of coverage. The beans and corn covers had the highest values of runoff and sediment yield, even higher than those observed for bare soil.

关键词： Runoff Erosion Semiarid region WESP model

Proximity of Problem-Based Learning(ABP)Methodology to Experimental Teaching in Organic *** Synthesis

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Journal of Chemistry and Chemical Engineering 2020年第1期14卷 16-25页

作者： elvira santos santos Eva Florencia Lejarazo Gómez Sara Suarez Torres Faculty of Chemistry National Autonomous University of MexicoMexico CityCoyoacán 04510Mexico

Different imines were *** reaction was carried out using different conditions,with aromatic aldehydes,aniline and with different energy ***,purity and experimental fusion point were calculated in each case,and they were compared to the ones found in *** importance of structural effects of aldehyde reacting with aniline was established as well as reaction *** efficacy of the reaction can not be predicted,since each aldehyde has a different structure and therefore reacts *** main objective of this project is academic.A methodology to carry out a structured research(it is one of the levels of problem-based learning(ABP)),was *** work in pairs using Combinatorial Chemistry,and each pair does a different exercise on the same theoretical *** from every team are discussed in a seminary where conclusions regarding which was the most efficient reaction are reached.

关键词： Problem-based ABP methodology experimental organic chemistry

Microencapsulated oregano and cinnamon essential oils as a natural alternative to reduce Listeria monocytogenes in Italian salami

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Food Bioscience 2022年第6期50卷 1766-1773页

作者： Franciele Maria Gottardo Bárbara Biduski Lára Franco dos santos Jucilene Sena dos santos Laura Beatriz Rodrigues Luciana Ruschel dos santos Graduate Program in Food Science and Technology University of Passo FundoBR 28599052-900Passo FundoRSBrazil Food Quality and Sensory Science Department Teagasc Food Research CentreAshtownDublinD15 KN3KIreland Graduate Program in Bioexperimentation University of Passo FundoBR 28599052-900Passo FundoRSBrazil College of Agronomy and Veterinary Science University of Passo FundoBR 28599052-900Passo FundoRSBrazil

Meat products are classified as perishable foods and have favourable conditions for the multiplication of microorganisms such as Listeria monocytogenes,an important pathogen associated with ready-to-eat *** compounds are used for food preservation combined with encapsulation techniques to improve *** study evaluated the anti-Listeria potential of isolated and combined microencapsulated oregano(OEO)and cinnamon(CEO)essential oils in Italian *** combination ratios of OEO and CEO were tested and 50:50 ratio(OEO:CEO)was encapsulated using sodium *** microcapsules were evaluated for encapsulation efficiency(EE),morphology and action against *** in a meat *** microcapsules and 50/50 combined EO were incorporated into the Italian salami to evaluate the physicochemical,microbiological and sensory *** combinations of EO showed *** inhibition zone and CIM with 1:16 *** microencapsulated EO had 98.36%encapsulation *** 2%microcapsule had a significant reduction of *** from the *** though the panellists mentioned the sandy attribute in the CATA,the salami with EO microcapsules texture did not differ from the *** the essential oils had high encapsulation efficiency,the smell and flavour of cinnamon and oregano interfered negatively with the sensory ***,the encapsulation of the combined essential oils(50/50)significantly reduced *** in Italian salami.

关键词： Natural antimicrobial Sodium alginate Ready-to-eat Encapsulation