Natural Elements
Mostrando 25-36 de 754 artigos, teses e dissertações.
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25. Comparative study between natural and synthetic Hydroxyapatite: structural, morphological and bioactivity properties
ABSTRACT In this work, a study of hydroxyapatite (HAp) powders obtained using both, porcine bones and chemical precursors was carried put. In the case of HAp obtained by means of porcine bones, physical processes as cooking, washing and milling were developed, for removing the organic material from the bones; after that, the powders were submitted to a therm
Matéria (Rio J.). Publicado em: 06/12/2018
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26. Understanding the Surfaces and Crystal Growth of Pyrite FeS2
Pyrite is a common sulfide mineral, which has arisen early interest by its euhedral shape and by its metallic glow similar to gold. However, it is only in our century that we began to understand pyrite crystal growth, considering the thermodynamic and kinetic aspects of crystal formation as a function of temperature and concentration of the elements present
Mat. Res.. Publicado em: 14/11/2018
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27. A Model Updating Method for Plate Elements Using Particle Swarm Optimization (PSO), Modeling the Boundary Flexibility, Including Uncertainties on Material and Dimensional Properties
Abstract It is a well-known fact that, in a real engineering situation, fixtures are not ideally stiff, so numerical simulations using them are unlikely to present results that are consistent with the experimental ones. The present paper intends to describe a model updating methodology inserting translational and rotational springs in order to better represe
Lat. Am. j. solids struct.. Publicado em: 22/10/2018
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28. Mineralogy, magnetic susceptibility and geochemistry of Fe-rich Oxisols developed from several parent materials
ABSTRACT: Fe-rich Oxisols on mafic rocks in Brazil generally have high magnetic susceptibility with high contents of some trace elements. These are taxonomically similar soils; however, differences in magnetic and geochemical properties may affect agricultural or environmental usability and subsequent management. This study investigated the pedogenesis of Fe
Sci. agric. (Piracicaba, Braz.). Publicado em: 2018-09
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29. Impact of Alloy Composition and Thermal Stabilization on Martensitic Phase Transformation Structures in CuAlMn Shape Memory Alloys
Alloys of CuAlMn are known as cheap, high strength shape memory alloys with an excellent damping capacity within their austenitic-martensitic phase transformation, compared to alloy systems like NiTi, CuZnAl or MnCu. But CuAlMn alloys have disadvantage due to generation of voids by a high shrinkage which further increases the existing proneness to stress cra
Mat. Res.. Publicado em: 19/07/2018
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30. Geochemistry and Spatial Variability of Rare Earth Elements in Soils under Different Geological and Climate Patterns of the Brazilian Northeast
ABSTRACT Growth in the agricultural and industrial sectors has increased the demand for rare earth elements (REEs) in the production of technological devices and fertilizers. Thus, the accumulation of these elements in the soil has become an environmental concern. Here, we aim to determine the natural contents of REEs in soils derived from different parent m
Rev. Bras. Ciênc. Solo. Publicado em: 02/07/2018
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31. NDVI and meteorological data as indicators of the Pampa biome natural grasslands growth
ABSTRACT The present study aimed to characterize the dynamics of NDVI and meteorological conditions, relating both to the annual dynamics of biomass accumulation in natural pastures of the Pampa biome as a way of subsidizing growth modeling. Forage accumulation rate data from a long-term experiment, NDVI data from the MODIS images, and meteorological data me
Bragantia. Publicado em: 23/04/2018
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32. Interfacial Shear Stress with Pull-out Test at Zeolite Ceramic Matrix and SS316 Single Fiber
ABSTRACT Natural zeolite ceramic is a material that can be used as bioceramics but it is fragile to crack. The weakness of ceramics can be overcome by making ceramic metals. The use of SS316 (stainless steel 316) fiber to strengthen the zeolite ceramic had been done in order to determine the interfacial relationship by using a fiber pull-out test. The conten
Matéria (Rio J.). Publicado em: 05/03/2018
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33. PHYSICAL-MECHANICAL CHARACTERIZATION OF Eucalyptus urophylla WOOD
ABSTRACT: Eucalyptus urophylla consists in a wood-producing species, which offers a natural multiple raw material of good quality for applications in rural and civil constructions. However, Eucalyptus urophylla still has a small utilization as building parts and elements, resulting from the possible ignorance and low diffusion of its structural possibilities
Eng. Agríc.. Publicado em: 2017-09
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34. FTIR study of aquamarines after gamma irradiation, heat treatment and electrodiffusion
Abstract Beryl, Be3Al2(SiO3)6, is a natural gemstone with many colors. Some of these colors can be induced or modified by exposure to ionizing radiation, by heating, and maybe by electrodiffusion. Small contents of chromophore chemical elements are related to the colors of beryl, like iron, chromium, vanadium, manganese, and others. There is great interest i
REM, Int. Eng. J.. Publicado em: 2017-09
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35. Analog Models of Flanking Structures and a Natural Example in the Quadrilátero Ferrífero, Minas Gerais
ABSTRACT The aim of this study is to present analog models of flanking structures and to analyze the Fábrica Nova synform, Quadrilátero Ferrífero, Minas Gerais, from a geometric point of view. We set up seven models using a linear viscous silicone and produced flanking structures with a shear velocity of 2 cm h-1. At different initial orientations with re
An. Acad. Bras. Ciênc.. Publicado em: 31/07/2017
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36. SIMULATION OF VENTILATION SYSTEMS IN A PROTECTED ENVIRONMENT USING COMPUTATIONAL FLUID DYNAMICS
ABSTRACT Computational simulations of mass and energy flow help in implementing alternative cooling systems in protected environments. The aim of this study was to model and simulate the interaction between external and internal environments of a protected environment by means of computational fluid dynamics (CFD) techniques and validate micrometeorological
Eng. Agríc.. Publicado em: 2017-06