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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

Broadband Optical Active Waveguides Written by Femtosecond Laser Pulses in Lithium Fluoride

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Chinese Physics Letters 2014年第1期31卷 72-75页

作者： Ismael Chiamenti Francesca Bonfigli Anderson s. L. Gomes Rosa Maria Montereali Larissa N. da costa Hypolito j. Kalinowski Federal University of Technology- Parang 80230-901 Curitiba Brazil ENEA C. R. Frascati Photonics Micro and Nanostructures Laboratory UTAPRAD-MNF V. E. Fermi 45 00044 Frascati (Rome) Italy Department of Physics Universidade Federai de Pernambuco necife Brazil

Broadband waveguiding through light-emitting strips directly written in a blank lithium fluoride crystal with a femtosecond laser is reported. Light guiding was observed at several optical wavelengths, from blue, 458 nm, to near-infrared, at 155nm. Visible photoluminescence spectra of the optically active F2 and F33 color centers produced by the fs laser writing process were measured. The wavelength-dependent refractive index increase was estimated to be in the order of 10-3-10-4 in the visible and near-infrared spectral intervals, which is consistent with the stable formation of point defects in LiF.

关键词： POINT defects CRYsTAL defects IMPURITY centers ANTIsITE defects INTERsTITIALs FLUX pinning

Improved dark ambient degradation of organic pollutants by cerium strontium cobalt perovskite

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journal of Environmental sciences 2020年第4期32卷 110-118页

作者： Huihuang Chen julius Motuzas Wayde Martens joao C.Diniz da costa The University of Queensland FIM^2 Lab-Functional Interfacial Materials and Membranes LaboratorySchool of Chemical EngineeringBrisbaneQld 4072Australia Hefei National Laboratory for Physical sciences at the Microscale University of Science and Technology of ChinaAnhui 230026China science and Engineering Faculty Queensland University of TechnologyBrisbaneQld 4000Australia LAQV-REQUIMTE (Bio)Chemical Process EngineeringDepartment of ChemistryFaculty of Science and TechnologyUniversidade NOVA de LisboaCaparica 2829-516Portugal

This work investigates the effect of cerium substation into strontium cobalt perovskites(CesrCoO)for the oxidative degradation of OrangeⅡ(OII)in dark ambient conditions without the aid of any external stimulants such as light,heating or chemical *** OII degradation rate by CesrCoO reached 65%in the first hour,whilst for the blank sample without cerium(srCoO)took over 2 hr to reach the same level of OII ***,the cerium substitution improved the catalytic activity of the perovskite material,mainly associated with the Ce0.1sr0.9CoO3 perovskite *** contacting CesrCoO,the-N=Nazo bonds of the OII molecules broke down resulting in electron donation and the formation of *** electrons are injected into the CesrCoO and resulted in a redox pair of Co3+/Co2+,establishing a bridge for the electron transfer between OII and the ***,the electrons also formed reactive species(·OH)responsible for OII degradation as evidenced by radical trapping *** species were formed via the reaction between 02 and donated electrons from OII with the aid of cobalt redox *** the prepared materials dispensed with the need for light irradiation and additional oxidants,it opens a window of environmental applications for treating contaminated wastewaters.

关键词： dark catalysis Acid orange degradation Cerium substituted perovskite Catalytic activity

Accuracy details in realistic CFD modeling of an industrial centrifugal pump in direct and reverse modes

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journal of Thermal science 2010年第6期19卷 491-499页

作者： j.C. Páscoa F. j. silva j.s. Pinheiro D.j. martins Department of Electromechanical Engineering Center for Aerospace Sciences and Technology University of Beira Interior EFAFLU Bombas e Ventiladores s.A. R. S. Brás 269 Apartado 23 4494-909 Póvoa do Varzim Portugal

Numerical computation of the flowfield inside a pump is herein used as a numerical laboratory, subject to the limitations of modeling assumptions and to experimental verification. A numerical computation of the flow inside a real industrial centrifugal pump is performed that includes a very sophisticated geometry. Conversely to other computations, in this test case no simplification of the geometry was introduced. Numerical computations are obtained using spalart-Allmaras turbulence model. A detailed analysis of the turbulent flowstructure is performed for the design point and two off design conditions. Additional computations were performed in order to compare the numerical and experimental pump characteristics; these were obtained under normalized testing conditions. Further computations are presented for the pump working in reverse turbine mode (PAT). Detailed analyses of the flow allow a comparison of the internal flow losses when the pump is operating in direct and reverse mode. This is also useful to help in the selection of an adequate pump geometry that can work in both modes with best efficiency.

关键词： centrifugal pump impeller turbulence modeling spalart-Allmaras PAT

Compounds from stevia rebaudiana Bertoni leaves: An overview of non-conventional extraction methods and challenges

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Food Bioscience 2022年第2期46卷 108-121页

作者： Dj´essica Tatiane Raspe Camila da silva silvio Cl´audio da costa ograma de P´os-Graduaç˜ao em Ciˆencia de Alimentos Universidade Estadual de Maring´aAv.Colombo579087020-900Maring´aPRBrazil Departamento de Tecnologia Universidade Estadual de Maring´aAv.ˆAngelo Moreira da Fonseca180087506-370UmuaramaPRBrazil Departamento de Bioquímica Universidade Estadual de Maring´aAv.Colombo579087020-900Maring´aPRBrazil

To overcome the inconveniences related to its conventional obtainment of natural sweeteners and active compounds from stevia rebaudiana Bertoni,methods involving application of technology,such as ultrasound assisted extraction,microwave assisted extraction,extraction under pressurized conditions by means of pressurized liquid extraction,subcritical water extraction and supercritical fluid extraction have been *** this review,these emerging techniques were analyzed and discussed,the process variables and operational strategies,their impacts on the extraction and their comparison against the conventional techniques were *** and the possibility of operational automation,the use of less energy and solvents,in addition to the reduced complexity of the subsequent purification steps,make up viable alternatives suitable for a possible industrial *** processes leverage the concept of green chemistry,but still suffer limitations related to acquisition and maintenance costs,in addition to the effects of the action of some of these technologies remaining unexplored.

关键词： Active compounds Natural sweeteners steviol glycosides Technology application

Presence of Multidrug-Resistant E. coli, Enterococcusspp. and salmonellaspp. in Lakes and Fountains of Porto, Portugal

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journal of Water Resource and Protection 2013年第11期5卷 1117-1126页

作者： Carlos E. Flores Luís Loureiro Lucinda j. Bessa Paulo martins da costa 1ICBAs-Abel salazar Biomedical sciences Institute University of Porto Porto Portugal 2CIIMAR-Interdisciplinary Center for Marine and Environmental Research University of Porto Porto Portugal 1ICBAs-Abel salazar Biomedical sciences Institute University of Porto Porto Portugal 2Faculty of Sciences (FCUP) University of Porto Porto Portugal CIIMAR-Interdisciplinary Center for Marine and Environmental Research University of Porto Porto Portugal Tulane University School of Public Health and Tropical Medicine New Orleans USA

Urban lakes and fountains provide recreational activities that could facilitate the contact between humans, animals and biological agents. The objective of this work was to assess the water quality and safety of 17 lakes and 13 fountains in the city of Porto (Portugal), by detecting the presence of Escherichia coli, enterococci and salmonella spp., and analyzing their antimicrobial resistance. (For more information,please refer to the pdf.)

关键词： Antimicrobial Resistance Enterococcus spp. Escherichia coli salmonella spp. Fountains Lakes

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

In vitro antileishmanial effects of Physalis angulata root extract on Leishmania infantum

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journal of Integrative Medicine 2018年第6期16卷 404-410页

作者： Bruno j.se martins da silva sandro Wilson Gomes Pereira Ana Paula Drummond Rodrigues j.se Luiz martins Do Nascimento Edilene Oliveira silva Laboratory of structural Biology Institute of Biological SciencesFederal University of PardBelemPard 66075-110Brazil National Institute of science and Technology in structural Biology and Bioimaging(INCT-INBEB) Rio de Janeiro 21941-901Brazil Laboratory of Electron Microscopy Department of Health SurveillanceMinistry of HealthEvandro Chagas InstituteBelemPard 66087-082Brazil Laboratory of Molecular and Cellular Neurochemistry Institute of Biological SciencesFederal University of PardBelemPard 66075-110Brazil National Institute of science and Technology in Neuroimmunomodulation(INCT-NIM) Rio de Janeiro 21040-360Brazil

Objective： In the present study, we evaluated the effects of the aqueous extract of Physalis angulata root （AEPa） on Leishmania infanturn proliferation, morphology, and the driving mechanism in leishmanicidal activity and modulatory action on macrophages. Methods： I., infantum promastigotes were treated with 50 and 100 μg/mL AEPa for 72 h and then antipro- mastigote assay was performed by counts in a Newbauer chamber, morphological changes were analyzed by transmission electron microscopy and the mechanism of the leishmanicidal activity was detected. In addition, macrophages were infected with L. infantum and were used to evaluate anti-amastigote activity of AEPa and effects of AEPa on cytokine secretion after 72-hour treatment. Results： Treatment with AEPa reduced the numbers ofL infantum promastigotes （50% inhibitory concen- tration （ICso） = 65.9μg/mL; selectivity index （sI）= 22.1） and amastigotes （ICso = 37.9 μg/mL; sI = 38.5） compared with the untreated control. Amphotericin B reduced 100% of the promastigote numbers after 72 h of treatment （IC50 = 0.2μg/mL）. AEPa induced several morphological changes and increased the production of reactive oxygen species and apoptotic death in promastigotes after treating for 72 h. AEPa （100 μg/mL） promoted tumor necrosis factor-α secretion in macrophages infected with L. infantum after 72 h of treatment, but did not induce an increase in this cytokine in noninfected macrophages. In addition, AEPa showed no cytotoxic effect on j774-A1 cells （50% cytotoxic concentration 〉1000μg/mL）. Conclusion： AEPa presented antileishmanial activity against the promastigotes and amastigotes of I.. infantum without macrophage cytotoxicity; these results show that natural products such as P. angulata have leishmanicidal potential and in the future may be an alternative treatment for leishmaniasis.

关键词： Leishmanicidal activity Leishmania infantum Reactive oxygen species Apoptosis Physalis angulata

sociodemographic,biological,and psychosocial correlates of light-and moderate-to-vigorous-intensity physical activity during school time,recesses,and physical education classes

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journal of sport and Health science 2019年第2期8卷 177-182页

作者： Bruno G.G.da costa Kelly s.da silva jaqueline A.da silva Giseli Minatto Luiz R.A.de Lima Edio L.Petroski Research Centre in Physical Activity and Health Federal University of Santa Catarina Department of Physical Education Federal University of Santa Catarina Research Centre in Kineanthropometry and Human Development Federal University of Santa Catarina

Background: Identifying factors associated with physical activity(PA) is useful in planning interventions and policies. The aim of this study was to identify sociodemographic, biological, and psychosocial factors associated with PA performed in school ***: data collected for the present study included gender, age, socioeconomic status, body fat percentage, aerobic fitness, self-efficacy, attitudes,peer and parental support, and perception of school environment. Dependent variables were light-intensity PA(LPA) and moderate-to-vigorousintensity PA(MVPA) performed during school time, recesses, and physical education(PE) classes. Multiple regression analyses were ***: Participating adolescents(n = 567, 53% female, 12.9 ± 5.3 years) spent 5% of school time in MVPA and 27% in LPA, 15% of recesses in MVPA and 44% in LPA, and 16% of PE classes in MVPA and 41% in LPA. Boys engaged in more MVPA in all categories. Age was inversely related with MVPA and LPA in all periods, whereas body fat percentage was inversely related with MVPA in school time and PE classes. Attitude was inversely related with MVPA in all periods and with LPA in recesses. Considering PA to be good and enjoyable was positively associated with MVPA in school ***: Adolescents spent little time in PA during school. Future interventions should implement enjoyable activities at school.

关键词： Accelerometer Adolescents Attitude Physical education Public health self-efficacy