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Empirical mode decomposition of multiphase flows in porous media:characteristic scales and speed of convergence

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Petroleum Science 2020年第1期17卷 153-167页

作者： Nicolás Echebarrena Pablo D.Mininni gustavo A.Moreno YPF-Technology EnsenadaBuenos AiresArgentina CONICET Buenos AiresArgentina Physics Department IFIBASchool of Exact and Natural SciencesUniversity of Buenos AiresCONICETUniversity Campus1428 Buenos AiresArgentina

We apply a proper orthogonal decomposition(POD)to data stemming from numerical simulations of a fingering instability in a multiphase flow passing through obstacles in a porous medium,to study water injection processes in the production of hydrocarbon *** show that the time evolution of a properly defined flow correlation length can be used to identify the onset of the fingering *** of characteristic lengths for each of the modes resulting from the POD provides further information on the dynamics of the ***,using numerical simulations with different viscosity ratios,we show that the convergence of the POD depends non-trivially on whether the fingering instability develops or *** result has implications on proposed methods to decrease the dimensionality of the problem by deriving reduced dynamical systems after truncating the system’s governing equations to a few POD modes.

关键词： Two-phase flow Empirical mode decomposition Viscous fingering Porous media

Corrosion behavior of electron beam processed AZ91 magnesium alloy

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Journal of Magnesium and Alloys 2020年第4期8卷 1314-1327页

作者： Fatemeh Iranshahi Mohammad Bagher Nasiri Fernando gustavo Warchomicka Christof Sommitsch Institute of Materials Science Joining and FormingGraz University of TechnologyKopemikusgasse 24/1Graz 8010Austria

The increasing use of light alloys owing to their high performance makes magnesium alloys very attractive for the use in automotive and biomedical ***,it is well known that magnesium and its alloys have poor corrosion resistance in different atmospheric and aqueous *** a means of improving corrosion resistance through the microstructure modification,electron beam processing(EBP)was applied on the as-cast AZ91 magnesium *** evaluate the microstructure influence on the corrosion-resistant,the EB processed samples underwent a solution heat treatment and an artificial aging heat *** different obtained microstructures were investigated by standard microscopy and electrochemical corrosion tests to evaluate the microstructure and its effects on the corrosion resistance of AZ91 *** EBPed specimens show a significant microstructure refinement and homogenous distribution ofβ-phase at the grain boundaries surrounded by supersaturatedα-Mg which acts as a barrier against *** electrochemical corrosion test of the samples immersed in 3.5 wt%NaCl after 4 weeks indicates that the EBP improves the corrosion resistance of the alloy due to the nobler corrosion potential of supersaturated a-Mg and more stable protective hydroxide films compared to the heat-treated and as-cast conditions.

关键词： Magnesium alloys Electron beam processing Corrosion AZ91 Microstructure Grain refinement.

Training birdsong recognition using virtual reality

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Virtual Reality & Intelligent Hardware 2021年第5期3卷 397-406页

作者： Carlos ARCE-LOPERA María JoséARIAS gustavo CORRALES Department of Technology and Information Universidad IcesiCali 760046Colombia

Background In mega-biodiverse environments,where different species are more likely to be heard than seen,species monitoring is generally performed using bioacoustics ***,since bird vocalizations are reasonable estimators of biodiversity,their monitoring is of great importance in the formulation of conservation ***,birdsong recognition is an arduous task that requires dedicated training in order to achieve mastery,which is costly in terms of time and money due to the lack of accessibility of relevant information in field trips or even specialized *** technology based on virtual reality(VR)and spatial audio may improve species monitoring by enhancing information accessibility,interaction,and user *** This study used spatial audio,a Bluetooth controller,and a head-mounted display(HMD)to conduct an immersive training experience in *** moved inside a virtual world using a Bluetooth controller,while their task was to recognize targeted *** measured the accuracy of recognition and user engagement according to the User Engagement *** The experimental results revealed significantly higher engagement and accuracy for participants in the VR-based training system than in a traditional computer-based training *** four dimensions of the user engagement scale received high ratings from the participants,suggesting that VR-based training provides a motivating and attractive environment for learning demanding tasks through appropriate design,exploiting the sensory system,and virtual reality *** The accuracy and engagement of the VR-based training system were significantly high when tested against traditional *** research will focus on developing a variety of realistic ecosystems and their associated birds to increase the information on newer bird species within the training ***,the proposed VR-based training system must be tested with ad

关键词： Human computer interaction Virtual environment Birdsong Audio training User engagement

Sleep in children with eosinophilic esophagitis

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World Journal of Pediatrics 2021年第2期17卷 111-114页

作者： Isabela A Ishikura gustavo Moreira SergioTufik Monica L.Andersen Department of Psychobiology Universidade Federal de Sao Paulo(UNIFESP)Napoleao de Barros925 Vila ClementinoSao PauloSP 04024-002Brazil

Eosinophilic esophagitis(EoE)is a chronic immune-and antigen-mediated disease caused by infiltration of eosino-phils in esophagus tissue,which leads to morphological and functional abnormalities at this site[1].This disease was discovered in 1995 by Kelly et al.[2];since then,it has become increasingly recognized and discussed by research-ers[2,3].EoE affects children and adults and is three times more prevalent in males than in *** to a recent systematic review,there are 19.1 cases of EoE per 100,000 children/year,with a higher frequency in Western countries[4].

关键词： esophagitis al. esophagus

How to model the effect of mechanical erosion control practices at a catchment scale?

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International Soil and Water Conservation Research 2021年第3期9卷 370-380页

作者： Elizeu Jonas Didoné Jean Paolo Gomes Minella Daniel gustavo Allasia Piccilli Federal University of Santa Maria Department of Soil Science1000 Avenue RoraimaCamobiCEP 97105-900Santa MariaRSBrazil Federal University of Santa Maria Department of Environmental and Sanitary Engineering1000 Avenue RoraimaCamobiCEP 97105-900Santa MariaRSBrazil

Conservation agriculture practices are a crucial factor in mitigating and controlling erosion by *** address water erosion estimates,most environmental models use the USLE,RUSLE,and MUSLE *** practices that affect soil erosion by modifying the flow pattern,such as contour farming,strip farming,or terracing,are represented within these models as a support practice(P)***,due to the difficulty in accurately mapping the P-factor,many studies choose to ignore it,using only the default value P-factor 1 which represents the absence of sowing at the level or cultivation in *** study proposes a methodology that evaluates the current P-factor based on the angle between the crop row orientation and the elevation contour *** method was tested in four areas under soybean crop fields in southern Brazil,totaling 25 km^(2).The reason for choosing four areas is to select different characteristics of rural properties and topographic *** ideal values of the P-factor are expected to be between 0.5 and 0.6;however,in our case,a P-factor greater than 0.8 was obtained in 60%of the area,indicating the low occurrence of contour farming reduces erosion *** results show that policymakers could potentially use this methodology(angle between the crop rows and contour lines)to run soil-erosion risk scenarios for a broader application of contour *** allows the P-factor to be quantified via a thematic map instead of assigning uniform P-factor *** a detailed study of the P-factor on the slopes,there is a better understanding of where to target support practices to reduce erosion.

关键词： Conservation practices Modeling P-Factor Planting efficiency

Spatial heterogeneity of factors influencing forest fires size in northern Mexico

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Journal of Forestry Research 2014年第2期25卷 291-300页

作者： gustavo Perez-Verdin Marco Antonio Marquez-Linares Maricela Salmeron-Macias Instituto Politecnico Nacional CIIDIR–DGODurangoDgoMexico34220

In Mexico, forest fires are strongly influenced by environmental, topographic, and anthropogenic factors. A government-based database covering the period 2000-2011 was used to analyze the spatial heterogeneity of the factors influencing forest fire size in the state of Durango, Mexico. Ordinary least squares and geographically weighted regression models were fit to identify the main factors as well as their spatial influence on fire size. Results indicate that fire size is greatly affected by distance to roads, distance to towns, precipitation, temperature, and a population gravity index. The geographically weighted model was better than the ordinary least squares model. The improvement of the former is due to the influence of factors that were found to be non-stationary. These results suggest that geographic location determines the influence of a factor on fire size. While the models can be greatly improved with additional information, the study suggests the need to adopt fire management policies to more efficiently reduce the effect of anthropogenic factors. These policies may include more training for landowners who use fire for clearing, closure of roads, application of thinning, prescribed burning, and fire breaks in perimeters adjacent to roads.

关键词： Durango Mexico geographically weighted regression ordinary least squares stationarity

Non-phospholipid liposomes with high sterol content display a very limited permeability

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Science China Chemistry 2013年第1期56卷 40-47页

作者： CARBAJAL gustavo CUI Zhong-Kai LAFLEUR Michel Department of Chemistry Center for Self-assembled Chemical Structures (CSACS)Université de MontréalC.P.6128Succ.Centre VilleMontréalQuébec H3C 3J7Canada

We demonstrate that it is possible to form non-phospholipid fluid bilayers in aqueous milieu with a mixture of palmitic acid (PA),cholesterol (Chol),and cholesterol sulfate (Schol) in a molar proportion of 30/28/*** self-assemblies are shown to be bilayers in the liquid ordered *** are stable between pH 5 and *** this pH range,the protonation/deprotonation of PA carboxylic group is observed but this change does not appear to alter the stability of these bilayers,a behavior contrasting with that observed for binary mixtures of PA/Chol,and PA/*** multilamellar dispersions formed spontaneously from the PA/Chol/Schol mixture could be successfully extruded to form Large Unilamellar Vesicles (LUVs).These LUVs show interesting permeability properties,linked with their high sterol *** non-phospholipid liposomes can sustain a pH gradient (pH internal 8/pH external 6) 100 times longer than LUVs made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and cholesterol,with a molar ratio of 60/***,the non-phospholipid LUVs are shown to protect ascorbic acid from an oxidizing environment (1 mM iron(III)).Once entrapped in liposomes,ascorbic acid displays a degradation rate similar to that obtained in the absence of iron(III).These results show the possibility to form novel nanocontainers from a mixture of a monoalkylated amphiphile and sterols,with a good pH stability and showing interesting permeability properties.

关键词： liposomes nanovectors permeability pH gradient ascorbic acid

Morphological Characterization of Brazil Nut Tree (Bertholletia excelsa) Fruit Pericarp

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Journal of Renewable Materials 2019年第7期7卷 683-692页

作者： gustavo P.Petrechen Marcos Arduin JoséD.Ambrósio Materials Science and Engineering Postgraduate Program Federal University of São CarlosSão CarlosBrazil Center of Characterization and Materials Development Federal University of São CarlosSão CarlosBrazil Department of Botany Federal University of São CarlosSão CarlosBrazil Citlab-Science Innovation and Technology LaboratorySorocabaBrazil

This article presents the overall morphological structure of the Brazil nut tree(Bertholletia excelsa)fruit pericarp,from macro to nano *** acquired knowledge would be used for the development of new applications,like using the materials as fillers for biocomposites,or as a hierarchical architecture model for *** research was performed using stereo and light microscopy and conventional and force field emission scanning electron *** pericarp presents three layers:the exocarp,a dark gray,brittle and fragile outer layer;the mesocarp,a beige,dry,rigid,impermeable and fibrous intermediate layer;and the endocarp,an inner layer with similar characteristic as the exocarp,but formed next to the ***,the exocarp and the endocarp presented minor regions of sclereids,fibers and vascular cell bundles,inside major regions of parenchyma *** mesocarp presents a structure of fiber cells regions alternating with sclereids and vascular cells regions,arranged in a composite like arrangement,with the fibers cells bundles acting as randomly oriented disperse phases in a sclereid cells *** arrangement was associated with the mesocarp relative superior proprieties,indicating a great material for using as fillers for biocomposites or in biomimetics applications.

关键词： Bertholletia excelsa brazil nut fruit pericarp morphological structure microscopy

Evaluation of biostimulation and Tween 80 addition for the bioremediation of long-term DDT-contaminated soil

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Journal of Environmental Sciences 2015年第2期27卷 101-109页

作者： Bibiana Betancur-Corredor Nancy J.Pino Santiago Cardona gustavo A.Peuela GDCON Research Group Faculty of Engineering University Research Headquarters (SIU) University of Antioquia School of Geosciences and Environment Faculty of Mines National University of Colombia School of Microbiology University of Antioquia

The bioremediation of a long-term contaminated soil through biostimulation and surfactant addition was evaluated. The concentrations of 1,1,1-trichloro-2,2-bis（4-chlorophenyl）ethane（DDT） and its metabolites 1,1-dichloro-2,2-bis（4-chlorophenyl） ethane（DDD） and1,1-dichloro-2,2-bis（4-chlorophenyl） ethylene（DDE） were monitored during an 8-week remediation process. Physicochemical characterization of the treated soil was performed before and after the bioremediation process. The isolation and identification of predominant microorganisms during the remediation process were also carried out. The efficiency of detoxification was evaluated after each bioremediation protocol. Humidity and p H and the heterotrophic microorganism count were monitored weekly. The DDT concentration was reduced by 79% after 8 weeks via biostimulation with surfactant addition（B ＋ S） and 94.3%via biostimulation alone（B）. Likewise, the concentrations of the metabolites DDE and DDD were reduced to levels below the quantification limits. The microorganisms isolated during bioremediation were identified as Bacillus thuringiensis, Flavobacterium sp., Cuprivadius sp.,Variovorax soli, Phenylobacterium sp. and Lysobacter sp., among others. Analysis with scanning electron microscopy（SEM） allowed visualization of the colonization patterns of soil particles. The toxicity of the soil before and after bioremediation was evaluated using Vibrio fischeri as a bioluminescent sensor. A decrease in the toxic potential of the soil was verified by the increase of the concentration/effect relationship EC50 to 26.9% and 27.2% for B ＋ S and B, respectively, compared to 0.4% obtained for the soil before treatment and 2.5%by natural attenuation after 8 weeks of treatment.

关键词： DDT Soil Bioremediation Biostimulation Surfactant Toxicity