Simultaneous crystal structure, microstructure, and morphology modeling with convolution-based profile fitting of angle-dispersive synchrotron x-ray diffraction data was applied to retrieve the size-dependent lattice changes in nanocrystalline rutile TiO 2. The dominant prismatic crystallite morphology was adequately modeled using the parallelepiped geometry. As with anatase TiO 2 , opposing trends of decreasing c and increasing a parameter, as well as lattice expansion with decreasing average crystallite size were observed. A correlation between Ti vacancy abundance and lattice volume increase suggests a possible causative link.

No abstract

A técnica de difração de raios X tem sido amplamente utilizada para a determinação de fases cristalinas em materiais cerâmicos. Em argilas, a grande quantidade de quartzo e seu elevado grau de orientação dificultam a identificação e caracterização das demais fases presentes. Baseando-se no princípio da sedimentação, é apresentado neste trabalho um método simples e confiável para a determinação de argilominerais em materiais argilosos.

No abstract

No abstract

Agronomic performance of cauliflower genotypes under climatic conditions of SinopThe productivity of cauliflower depends on the interaction between genotype and environmental conditions. To minimize this effect it is necessary to identify genotypes with good stability and wide adaptability to different environmental conditions. We evaluated the agronomic performance and adaptability of cauliflower cultivars at Sinop, Mato Grosso state, Brazil, under field conditions in the period from March 4 th to July 22 nd , 2011. The experimental design was randomized blocks with eight treatments (Verona 184; Venice, Verona 284; First Snow; Sahara; Luna F1; Piracicaba Precoce and Quatro Estações) and eleven replications. The plots consisted of 36 plants distributed on the spacing of 80x60 cm and 16 plants were evaluated. The following characteristics were evaluated: fresh weight, curd diameter, yield, cycle and inflorescence classification. The hybrid cultivars Verona 184, Verona 284, Venice, Luna F1, First Snow and Sahara showed yield of 18.90; 18.70; 16.68; 16.14; 15.65 and 15.50 t ha -1 respectively and were classified as Extra. However, the cauliflower cultivars Piracicaba Precoce and Quatro Estações showed low productivity (6.67 and 5.12 t ha -1 , respectively) beyond its classification in category III. The hybrids Verona 184, Verona 284, Veneza, Luna F1, First Snow and Sahara present adaptation to be grown under the climatic conditions of Sinop. Cultivars Piracicaba Precoce and Quatro Estações are unfit for cultivation in Sinop because of its low yield and head quality.

No abstract

In the present study the thermal decomposition of a freeze-dried copper(II) acetate monohydrate powder, (CH 3 COO) 2 Cu . H 2 O, (FDCuAcH 2 O), was analysed by a combination of high-temperature X-ray diffractometry; differential scanning calorimetry and thermogravimetry, up to 700 °C. The structure and morphology of the calcined freeze-dried powders were analysed by scanning electron microscopy and X-ray diffractometry. The results showed that FDAcCuH 2 O decomposes during heating in two stages: I) (25-225 °C) FDCuAcH 2 O dehydrates giving rise to copper(II) acetate, (CH 3 COO) 2 Cu, (AcCu), and II) (225-525 °C) AcCu decomposes to CuO through complex oxidation reactions of Cu and Cu 2 O, simultaneously. SEM showed that FDCuAcH 2 O powder has a scale-like morphology, which is created in the freezing stage and retained after freeze-drying. After calcination at 125 and 225 °C, clusters of elongated tubes (or filaments) compose the resulting powder (AcCu). Subsequent calcination at temperatures above 325 °C resulted in hard clusters of spheroid-like CuO particles.