Behavior of adherence forces of the butyl mastic and silicone sealant adhesives

A pesquisa demonstra como é o comportamento de dois materiais conhecidos comercialmente como mastic em relação às forças de cisalhamento de selantes. No mercado existem dois tipos de mastic, um da família de silicones e outro da borracha butílica. A pesquisa teve o objetivo de esclarecer junto à receita federal e ao mercado, que as propriedades dos dois tipos são muito diferentes, apesar de ambos sofrerem um processo de cura. Com o tempo há aumento das forças de coesão e adesão de ambos, o que evidencia o processo de cura.This study reveals the response to shear forces for two materials known as mastic. There are two kinds of mastic in the market, one of the silicone family and another made with butyl rubber. The aim was to demonstrate to the Inland Revenue and to the market that these materials exhibit very distinct properties, although both undergo the curing process. As time goes by, there is an increase in the forces of cohesion and adhesion for both types of mastic, which is evidence of the curing process

Effect of conductivity, viscosity, and density of water-in-salt electrolytes on the electrochemical behavior of supercapacitors: Molecular dynamics simulations and: In situ characterization studies

We report here molecular dynamics simulations combined with in situ experimental studies to understand the advantages and disadvantages of replacing conventional (salt-in-water, SiWE) aqueous-based electrolytes with very concentrated (water-in-salt, WiSE) systems in supercapacitors. Atomistic molecular dynamics simulations were employed to investigate the energetic, structural, and transport properties of aqueous electrolytes based on sodium perchlorate (NaClO4). Simulations covered the concentrations range of 1 mol dm-3 (1 mol kg-1) to 8 mol dm-3 (15 mol kg-1), demonstrating a significant increase in viscosity and density and reduction in ionic conductivity as the concentration reaches the WiSE conditions. A carbon-based symmetric supercapacitor filled with WiSE showed a larger electrochemical stability window (ESW), allowing to span the cell voltage and specific energy. Larger ESW values are possible due to the formation of a solvent blocking interface (SBI). The formation of ionic aggregates owing to the increasing cohesive energy in WiSE disturbs the hydrogen-bond network resulting in physicochemical changes in the bulk liquid phase. In addition, the molal ratio between water and ions is decreased, resulting in a low interaction of the water molecules with the electrode at the interface, thus inhibiting the water-splitting considerably.Fil: Da Silva, Débora A. C.. Universidade Estadual de Campinas; BrasilFil: Pinzón, Manuel J.. Universidade Estadual de Campinas; BrasilFil: Messias Da Silva, Andresa. Universidad Federal do Abc; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Fileti, Eudes E.. Universidade de Sao Paulo; BrasilFil: Pascon, Aline. Universidade Estadual de Campinas; BrasilFil: Franco, Débora V.. University of Jequitinhonha e Mucuri's Valley; BrasilFil: Da Silva, Leonardo Morais. University of Jequitinhonha e Mucuri's Valley; BrasilFil: Zanin, Hudson G.. Universidade Estadual de Campinas; Brasi

Hemispheric asymmetry in the sunspot cycle as a nonextensive phenomenon

The appearance of dark sunspots over the solar photosphere is not considered to be symmetric between the northern and southern hemispheres. Among the different conclusions obtained by several authors, we can point out that the North-South asymmetry is a real and systematic phenomenon and is not due to random variability. In the present work, we selected the sunspot area data of a sample of 13 solar cycles divided by hemisphere extracted from the Marshall Space Flight Centre (MSFC) database to investigate the behavior of probability distributions using an out-of-equilibrium statistical model a.k.a non-extensive statistical mechanics. Based on this statistical framework, we obtained that the non-extensive entropic parameter $q$ has a semi-sinusoidal variation with a period of $\sim$22 year (Hale cycle). Among the most important results, we can highlight that the asymmetry index $q(A)$ revealed the dominance of the northern hemisphere against the southern one. Thus, we concluded that the parameter $q(A)$ can be considered an effective measure for diagnosing long-term variations of the solar dynamo. Finally, our study opens a new approach to investigating solar variability from the nonextensive perspective.Comment: 17 pages, 2 tables and 5 figures. Submitted to Solar Physic

A rational experimental approach to identify correctly the working voltage window of aqueous-based supercapacitors

It is common to find in the literature different values for the working voltage window (WVW) range for aqueous-based supercapacitors. In many cases, even with the best intentions of the widening the operating voltage window, the measured current using the cyclic voltammetry (CV) technique includes a significant contribution from the irreversible Faradaic reactions involved in the water-splitting process, masked by fast scan rates. Sometimes even using low scan rates is hard to determine precisely the correct WVW of the aqueous-based electrochemical capacitor. In this sense, we discuss here the best practices to determine the WVW for capacitive current in an absence of water splitting using complementary techniques such as CV, chronoamperometry (CA), and the electrochemical impedance spectroscopy (EIS). To accomplish this end, we prepare and present a model system composed of multiwalled carbon nanotubes buckypaper electrodes housed in the symmetric coin cell and soaked with an aqueous-based electrolyte. The system electrochemical characteristics are carefully evaluated during the progressive enlargement of the cell voltage window. The presence of residual Faradaic current is verified in the transients from the CA study, as well as the impedance changes revealed by EIS as a function of the applied voltage, is discussed. We verify that an apparent voltage window of 2.0 V determined using the CV technique is drastically decreased to 1.2 V after a close inspection of the CA findings used to discriminate the presence of a parasitic Faradaic process. Some orientations are presented to instigate the establishment in the literature of some good scientific practices concerned with the reliable characterization of supercapacitors10CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP310544/2019-0; 301095/2018-32014/02163-7; 2017/11958-1; 2018/20756-

Cursos de campo sobre polinización: una propuesta pedagógica

A polinização é um importante serviço ecológico para o funcionamento dos ecossistemas. É um processo chave na produção de alimentos e na conservação da biodiversidade, pois os polinizadores asseguram a reprodução da maioria das espécies vegetais com flores. Para viabilizar ações que visem a conservação e o uso sustentável dos polinizadores é essencial investir na formação de profissionais para atuarem nesse campo do conhecimento. Nesse contexto, iniciativas voltadas para o desenvolvimento de estratégias pedagógicas inovadoras, que logrem bons resultados em curto espaço de tempo devem ser incentivadas. Os cursos internacionais de campo sobre polinização é uma dessas iniciativas. O curso visa qualificar pesquisadores, docentes de instituições de ensino superior, discentes de pós-graduação e demais profissionais que atuam na área de polinização e/ou que possuem o perfil para atuarem nesta área, como futuros pesquisadores, formadores de recursos humanos e disseminadores de conhecimentos em nível local e/ou regional. O formato original desses cursos foi concebido e desenvolvido pelo Prof. Dr. Peter Kevan, da Universidade de Guelph no Canadá, na década de 90. No Brasil já foram realizadas cinco edições desses cursos, sendo quatro na Bahia (Chapada Diamantina) e uma no Ceará (Limoeiro do Norte). A sexta edição está sendo preparada para novembro de 2010, no Rio Grande do Sul e a sétima para 2011, no Pará. O curso é teórico e prático e tem a duração de duas semanas. A proposta pedagógica e o cronograma do curso serão apresentados neste artigo.Pollination is an important and ecological service for ecosystem function. It is a key process for food production and biodiversity conservation because pollinators mediate reproduction in most flowering plant species. To take practical actions directed to conservation and sustainable management of pollinators, it is essential to invest in training experts with appropriately deep knowledge in the field. In this context, initiatives devoted to improving novel pedagogical strategies that generate highly qualified personnel in a short time must be improved. The international pollination field course is one of such initiatives. The aim of this course is to qualify researchers, professors at higher education institutions, undergraduate and graduate students and other professionals working in the general area of pollination with practical and theoretical skills as future researchers, human resource trainers and disseminators of knowledge in local and/or regional levels. The original format of the course was conceived and developed by Professor Dr. Peter Kevan, from University of Guelph, in Canada, in the 1990’s. In Brazil, the course has been offered five times to date four times in Bahia (Chapada Diamantina) and once in Ceará (Limoeiro do Norte). The sixth presentation is being organized for November 2010, in Rio Grande do Sul state and the seventh for 2011, in Pará state. The course, with both theoretical and practical phases, lasts two weeks. The pedagogical details and chronogram of the course are presented in this article.La polinización es un importante servicio ecológico para el funcionamiento de los ecosistemas. Es un proceso clave en la producción de alimentos y en la conservación de la biodiversidad, pues los polinizadores garantizan la reproducción de la mayoría de las especies vegetales con flores. Para viabilizar acciones que busquen la conservación y el uso sostenible de los polinizadores, es esencial invertir en la formación de profesionales que actúen en ese campo del conocimiento. En este contexto, deben ser incentivadas iniciativas dirigidas al desarrollo de estrategias pedagógicas innovadoras, que logren buenos resultados en un corto intervalo de tiempo. Los cursos internacionales de campo sobre polinización son una de esas iniciativas. El curso pretende formar investigadores, docentes de instituciones de educación superior, alumnos de posgrado y demás profesionales que actúan en el área de polinización y/o poseen el perfil para actuar en esta área, como futuros investigadores, formadores de recursos humanos y divulgadores de conocimiento a nivel local y/o regional. El formato original de estos cursos fue concebido y desarrollado por el profesor Dr. Peter Kevan, de la Universidad de Guelph, en Canadá, en la década de 1990. En Brasil han sido realizadas cinco ediciones de estos cursos, cuatro en Bahia (Chapada Diamantina) y una en Ceará (Limoeiro do Norte). La sexta edición está siendo preparada para noviembre de 2010, en Rio Grande do Sul y la séptima para 2011, en Pará. El curso es teórico y práctico y tiene una duración de dos semanas. La propuesta pedagógica y el cronograma del curso serán presentados en este artículoFil: Viana, Blandina Felipe. Universidade Federal da Bahia. Instituto de Biología. Departamento de Zoologia. Laboratório de Biologia e Ecologia de Abelhas; Brasil. Universidade Federal da Bahia. Instituto de Biologia. Programa de Pós-Graduação em Ecologia e Biomonitoramento; BrasilFil: Freitas, Breno Magalhães. Universidade Federal do Ceará. Departamento de Zootecnia. Grupo de Pesquisa com Abelhas; BrasilFil: Silva, Fabiana Oliveira Da. Universidade Federal da Bahia. Instituto de Biologia. Programa de Pós-Graduação em Ecologia e Biomonitoramento; BrasilFil: Oliveira, Favizia Freitas De. Universidade Estadual de Feira de Santana. Depto. de Ciências Biológica. Laboratório de Sistemática de Insetos; BrasilFil: Galetto, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); ArgentinaFil: Kevan, Peter G.. Universiy of Guelph. Department of Environmental Biology. Applied Ecology and Anthecology Laboratory; Canad

Reduced graphene oxide multilayers for gas and liquid phases chemical sensing

Graphene oxide (GO) multilayers were produced by the layer-by-layer technique after successive immersions of quartz slides into aqueous suspensions of cationic poly(diallyldimethyl ammonium chloride) (PDAC) and anionic GO. The adsorbed amount of GO within the multilayers measured ex situ by UV-vis spectroscopy was found to increase linearly with the number of PDAC-GO bilayers. UV-vis and Raman spectra confirmed the conversion of GO to its reduced form, namely reduced graphene oxide (RGO), when the multilayers were subjected to hot hydrazine. According to AFM images, multilayers are flat with GO sheets forming edge structures. Additionally, impedance spectroscopy provided information regarding the multilayer growth mechanism, which starts with isolated GO sheets that bridge each other after deposition of five PDAC-GO bilayers. As a proof of principle, it was demonstrated that a sensor array composed by reduced multilayers deposited onto interdigitated microelectrodes and interrogated by impedance spectroscopy is capable of discriminating vapours of volatile solvents, including toluene, gasoline, ethanol, chloroform, and acetone, as well as chemicals in aqueous solutions, such as hydrochloric acid, sodium chloride, ammonium hydroxide, and sucrose. This capability was made possible only because the LbL assembly permitted one to tune the sensors' sensitivity with the number of PDAC-GO bilayers. The results presented herein suggest that the reduced PDAC-GO multilayers are promising elements for non-specific chemical sensors.CNPq (308038/2012-6)CAPE

Variabilidade da Skewness da Temperatura Potencial Equivalente na Floresta Nacional de Caxiuanã, PA

Potential equivalent temperature ( θe ) data have been analyzedregarding 2008 wet season (Julian day 64) and dry season (Julian day276). The data have been measured upon 10 Hz sampling rate at ameteorological tower built in National Caxiuanã Forest, Pará. The resultsaccusing difference to Skewness of θe value during daytime period andvalue alternate Skewness of θe to nightly period, to one day for eachseason (wet and dry).Foram analisados dados da temperatura potencial equivalente( θe ) ao longo de dois dias (julianos) do ano de 2008: 64, no períodoúmido, e 276, no período seco, com dados amostrados a 10 Hz, em torreda Floresta Nacional de Caxiuanã, Pará. Os resultados indicam diferençaspara valores da Skewness de θe no período diurno, e alternância devalores da Skewness de θe para o período noturno, durante um dia decada estação (úmida e seca)

A self-organizing map clustering approach to support territorial zoning

This work aims to evaluate three strategies for analyzing clusters of ordinal categorical data (thematic maps) to support the territorial zoning of the Alto Taquari basin, MS/MT. We evaluated a model-based method, another based on the segmentation of the multi-way contingency table, and the last one based on the transformation of ordinal data into intervals and subsequent analysis of clusters from a proposed method of segmentation of the Self-Organizing Map after the neural network training process. The results showed the adequacy of the methods based on the Self-Organizen Map and the segmentation of the contingency table, as these techniques generated unimodal clusters with distinguishable groups.Supported by National Council for Scientific and Technological Development –CNPq, Brazil, and by National Funds through the Portuguese funding agency, FCT -Fundação para a Ciência e a Tecnologia within project 2022.06822.PTDC. The work of Pedro Oliveira was also supported by the doctoral Grant PRT/BD/154311/2022 financed by the Portuguese Foundation for Science and Technology (FCT), and with funds from European Union, under MIT Portugal Progra

Estudos sobre a paz e cultura da paz

Segundo o autor, a cultura da paz implica uma mudança quer na forma como a “alta cultura” lida com a realidade quer no tipo de abordagem que o senso comum faz às relações sociais, sendo que a ruptura com a ideologia conservadora, ou seja, com o senso comum realista só é possível graças a estas alterações. O autor realça tanto a importância que os estudos sobre a paz têm para o surgimento de um conceito amplo de paz, desenvolvido por Johan Galtung, como o facto destes estarem estrategicamente orientados para a transformação do sistema internacional. Sequentemente, conclui que a paz é uma categoria moral e cultural que só pode ser alcançada através do comportamento quotidian