DESENVOLVIMENTO DE UMA MESA BIRROTATIVA MODULAR PARA INTEGRAÇÃO COM FRESADORAS CNC DE BAIXO CUSTO VISANDO USINAGENS DE MODELOS COMPLEXOS EM CINCO EIXOS SIMULTÂNEOS

A usinagem de modelos com geometria complexa é uma atividade bastante executada na indústria de manufatura. Contudo, dependendo da complexidade do modelo a ser usinado em máquinas de três eixos, o processo tornase demorado ou até mesmo impossível de ser realizado. Os modelos complexos são fabricados utilizando-se fresadoras CNC de porte industrial com quatro ou cinco eixos, porém, o elevado custo destes equipamentos torna a aplicação inviável, principalmente nas situações que envolvem a fabricação de produtos com baixo valor agregado. O presente artigo descreve o desenvolvimento de uma mesa birrotativa modular com seu sistema de acionamento e controle para integração em fresadoras CNC de três eixos de baixo custo aplicadas na modelagem e prototipagem rápida. Este tipo de desenvolvimento é muito promissor pelo fato de abrir uma possibilidade de expandir recursos de interpolação de uma fresadora com o mínimo de alterações mecânicas e elétricas na máquina original, podendo também voltar a operar em sua confi guração original. Um protótipo foi construído e instalado na fresadora CNC TRIAC PC com o objetivo de validar o conceito de integração e modularidade. O modelo virtual da confi guração cinemática foi gerado em sistema CAD/CAM para possibilitar a programação em cinco eixos simultâneos

Quantitative study of hydration of C3S and C2S by thermal analysis. Evolution and composition of C-S-H gels formed

This research is part of a European project (namely, CODICE project), main objective of which is modelling, at a multi-scale, the evolution of the mechanical performance of non-degraded and degraded cementitious matrices. For that, a series of experiments were planned with pure synthetic tri-calcium silicate (C3S) and bi-calcium silicate (C2S) (main components of the Portland cement clinker) to obtain different calcium–silicate–hydrate (C–S–H) gel structures during their hydration. The characterization of those C–S–H gels and matrices will provide experimental parameters for the validation of the multi-scale modelling scheme proposed. In this article, a quantitative method, based on thermal analyses, has been used for the determination of the chemical composition of the C–S–H gel together with the degree of hydration and quantitative evolution of all the components of the pastes. Besides, the microstructure and type of silicate tetrahedron and mean chain length (MCL) were studied by scanning electron microscopy (SEM) and 29Si magic-angle-spinning (MAS) NMR, respectively. The main results showed that the chemical compositions for the C–S–H gels have a CaO/SiO2 M ratio almost constant of 1.7 for both C3S and C2S compounds. Small differences were found in the gel water content: the H2O/SiO2 M ratio ranged from 2.9 ± 0.2 to 2.6 ± 0.2 for the C3S (decrease) and from 2.4 ± 0.2 to 3.2 ± 0.2 for the C2S (increase). The MCL values of the C–S–H gels, determined from 29Si MAS NMR, were 3.5 and 4 silicate tetrahedron, for the hydrated C3S and C2S, respectively, remaining almost constant at all hydration periods

Potential geographic distribution of Hantavirus reservoirs in Brazil

Hantavirus cardiopulmonary syndrome is an emerging zoonosis in Brazil. Human infections occur via inhalation of aerosolized viral particles from excreta of infected wild rodents. Necromys lasiurus and Oligoryzomys nigripes appear to be the main reservoirs of hantavirus in the Atlantic Forest and Cerrado biomes. We estimated and compared ecological niches of the two rodent species, and analyzed environmental factors influencing their occurrence, to understand the geography of hantavirus transmission. N. lasiurus showed a wide potential distribution in Brazil, in the Cerrado, Caatinga, and Atlantic Forest biomes. Highest climate suitability for O. nigripes was observed along the Brazilian Atlantic coast. Maximum temperature in the warmest months and annual precipitation were the variables that most influence the distributions of N. lasiurus and O. nigripes, respectively. Models based on occurrences of infected rodents estimated a broader area of risk for hantavirus transmission in southeastern and southern Brazil, coinciding with the distribution of human cases of hantavirus cardiopulmonary syndrome. We found no demonstrable environmental differences among occurrence sites for the rodents and for human cases of hantavirus. However, areas of northern and northeastern Brazil are also apparently suitable for the two species, without broad coincidence with human cases. Modeling of niches and distributions of rodent reservoirs indicates potential for transmission of hantavirus across virtually all of Brazil outside the Amazon Basin

O corpo despido pelas práticas de desenhar: dos usos à disciplinarização do desenho

Inserido na problemática de investigação sobre os motivos pelos quais as práticas socioculturais de desenhar teriam adquirido e perdido o estatuto de conteúdo escolar, este artigo tem por objetivo refletir acerca dos diferentes usos dados à prática do desenho do corpo humano em duas atividades específicas: a atividade artística e a atividade médica. Parte-se do pressuposto de que a compreensão de características da vida escolar das práticas de desenhar exige a investigação dessas práticas em espaços não escolares. Como a prática do desenho do corpo tem atravessado os espaços escolares brasileiros, é nosso interesse, portanto, investigar como se pôde formar tal domínio de saber. Nesse sentido, nossa estratégia será analisar que problemáticas permearam tal prática durante o Renascimento, a fim de compreender possíveis implicações filosóficas, conceituais, técnicas e científicas decorrentes de suas diversas significações

NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

Xenarthrans – anteaters, sloths, and armadillos – have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with 24 domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, ten anteaters, and six sloths. Our dataset includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data-paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the south of the USA, Mexico, and Caribbean countries at the northern portion of the Neotropics, to its austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n=5,941), and Cyclopes sp. has the fewest (n=240). The armadillo species with the most data is Dasypus novemcinctus (n=11,588), and the least recorded for Calyptophractus retusus (n=33). With regards to sloth species, Bradypus variegatus has the most records (n=962), and Bradypus pygmaeus has the fewest (n=12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other datasets of Neotropical Series which will become available very soon (i.e. Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans dataset