A composição química dos óleos essenciais foi utilizada para estudar a estrutura espacial de oito populações de Eugenia dysenterica do Cerrado central brasileiro. O particionamento da variação utilizando os conjuntos de dados espaciais e ambientais como preditores foi altamente significativo e explicou 7,8 e 8,1% da variação total dos óleos essenciais, respectivamente. Os resultados sugeriram que o polimorfismo nos óleos essenciais foi determinado mais por fatores genéticos do que ambientais. Além disso, o intercepto do autocorrelograma multivariado de Mantel entre as matrizes de distância dos constituintes químicos e dos locais de coleta sugere que as populações se diferenciam quimicamente a distâncias geográficas superiores a 120 km, contribuindo como indicador alternativo da distância mínima entre amostras necessária para a conservação da diversidade genética das populações.The chemical composition of essential oils was used to study the spatial structure of eight Eugenia dysenterica populations in central Brazilian Cerrado. Variation partitioning using spatial and environmental data sets as predictors was highly significant and explained 7.8 and 8.1% of oil chemovariations, respectively. Results suggested that essential oil polymorphism was genetically rather than environmentally determined. Furthermore, the intercept of the multivariate Mantel autocorrelogram between the distance matrices of oil constituents and sampling sites suggested that the populations differ chemically whenever geographical distance exceeds 120 km. It stands, therefore, as an alternative indicator of the minimal distance between samples required for conserving the genetic diversity of populations.Keywords: Eugenia dysenterica, essential oil, variation partitioning, spatial pattern, spatial autocorrelation IntroductionThe Cerrado Biome spans about a quarter of the Brazilian territory and is characterized by the phytophysiognomic gradient from grassland to forest formations.1 Despite Cerrado status as a biodiversity hotspot which houses over 11,000 species of native plants, including 4,400 endemic species, only about 2.2% of its area enjoys legal protection. 2Central Brazilian Cerrado was severely fragmented and degraded by deforestation in the early 1950s, a process accelerated in the 1970s with the expansion of the agricultural frontier. 3 An estimation by remote sensing shows that about 47.8% of Cerrado original vegetation had been cleared by 2008 mainly due to cultivated pastures and agricultural crops. 4 After the Atlantic Forest, Cerrado is the Brazilian Biome that has suffered the greatest anthropogenic impacts, and has been classified among the most threatened biomes in the world. 5 Thus, strategies to manage, conserve and domesticate wild species are required for the sustainable exploitation of this region.Among the many tree species found in the Cerrado Biome, Eugenia dysenterica DC. (Myrtaceae), or "cagaiteira" tree, is unique because of its wide range of uses by local human populations.6 Its fruits are appreciated for their ...
O trabalho consistiu em avaliar o desempenho de dois tipos de carbonato de cálcio (um de origem mineral e outro de origem cretácea) utilizados na formulação de tubos de PVC rígido. Os tubos foram produzidos pelo processo de extrusão e o desempenho do material foi analisado com a realização de testes de controle de qualidade propostos pela ABNT. Os resultados dos testes de qualidade foram bem mais satisfatórios nos tubos que possuíam em sua composição o carbonato de origem cretácea. Para verificar as diferenças existentes entre os carbonatos foi realizada uma análise de difratometria de raios-X, que indicou conformações cristalinas romboédrica e monoclínica para os carbonatos de origem cretácea e mineral, respectivamente. A possível existência de "cantos vivos" na conformação monoclínica do carbonato mineral e consequentemente a formação de espaços vazios na estrutura do polímero teriam causado os resultados negativos nos testes de qualidade do produto final. Palavras-chave: PVC (policloreto de vinila), carbonato de cálcio, controle de qualidade.The work was to evaluate the performance of two types of calcium carbonate (a source of mineral and other cretaceous origin) used in the formulation of rigid PVC pipes. The tubes were produced by extrusion process and the performance of the material was analyzed with the testing of quality control offered by ABNT. The results of quality tests were much more satisfactory in the tubes that had their composition in the Cretaceous carbonate source. To verify the differences between the carbonates was an analysis of X-ray diffraction, which indicated rhombohedral and monoclinic crystal conformations for the origin of cretaceous carbonates and mineral, respectively. The possible existence of "sharp corners" in complying monoclinic carbonate mineral and consequently the formation of voids in the polymer structure would have caused the negative results in tests on final product quality..
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