Room temperature ferromagnetism in combustion reaction prepared iron-doped zinc oxide nanoparticles

We present a study of the structural and magnetic properties of Zn_1?xFe_xO (0.00≤x≤0.09) nanoparticles prepared by a combustion reaction method. X-ray diffraction patterns of all samples showed sharp and intensive peaks of hexagonal wurtzite structure of ZnO without any evidence of spurious crystalline phases in all samples. The magnetic properties were measured by using a vibrating sample magnetometer. Hysteresis loop indicated that all samples are ferromagnetic at room temperature and the Curie temperature increased with increasing iron content. Room temperature ferromagnetism can be explained in terms of intrinsic properties and the presence of defects in Fe- doped ZnO nanoparticles.     

Strategies for production of parts textured by grinding using patterned wheels

The functionalization of surfaces by introducing pre-engineered textures is a new requirement from industry. Surfaces more prone to promote micro-lubrication are being designed by engineers and incorporated into the components specification. The major challenge is to develop manufacturing methods able to produce these textures in a repeatable and economically viable way. The aim of this research work is to develop grinding strategies based on the method proposed in [1] for producing textured surfaces by grinding. The characteristics of the produced textures are measured and evaluated using new proposed parameters. The obtained results show the potential of this process solution for the production of micro pockets for hydrodynamic bearings application.     

Microdevices for extensional rheometry of low viscosity elastic liquids: a review

Extensional flows and the underlying stability/instability mechanisms are of extreme relevance to the efficient operation of inkjet printing, coating processes and drug delivery systems, as well as for the generation of micro droplets. The development of an extensional rheometer to characterize the extensional properties of low viscosity fluids has therefore stimulated great interest of researchers, particularly in the last decade. Microfluidics has proven to be an extraordinary working platform and different configurations of potential extensional microrheometers have been proposed. In this review, we present an overview of several successful designs, together with a critical assessment of their capabilities and limitations.     

Space-time dynamics of deforestation in Brazilian Amazônia

Deforestation maps derived from Landsat Multi-Spectral Scanner (MSS) and Thematic Mapper (TM) imagery were used to analyse spatial patterns of deforestation in the 1970s and the 1991-1997 period in Brazilian Legal Amazonia. Nearly 90% of the deforestation has occurred within 100 km from major roads established under federal development programmes. Clearings larger than 50 ha and 200 ha accounted, respectively, for 74% and 50% of the total deforestation in the 1991-1997 period. Results show that more intense deforestation has been concentrated over some regions, leading to the continuous enlargement of forest clearings and contributing to aggravate deforestation impacts in such areas.     

Influence of Surfactant on the Thermal Behavior of Marigold Oil Emulsions with Liquid Crystal Phases

ABSTRACT

Vegetable oils have been largely consumed owing to the interest of pharmaceutical and cosmetic industries in using natural raw materials. The production of stable emulsions with vegetable oils challenges formulators due to its variability in composition and fatty acids constitution within batches produced. In the present work, it was studied that the influence of the size of carbon chain and the number of ethylene oxide moieties of the surfactant on the thermal behavior of eight emulsions prepared with marigold oil stabilized by liquid crystal phases. Differential scanning calorimetry (DSC) was used to determine the thermal behavior of the emulsions. The ratio of bound water was calculated, being between 29.0 and 42.0%, confirming the extension of the liquid-crystalline net in the external phase. Changing the lipophilic surfactant from Ceteth-2 to Steareth-2, there was an increase in the temperature of phase transition of the liquid crystal influencing the system stability. Calorimetric study is very useful in understanding the performance of liquid crystals with the increase of temperature and to estimate emulsions stability.     

Volatile components of mangaba fruit (Hancornia speciosa Gomes) at three stages of maturity

The effect of stage of maturity on the volatile components of mangaba fruit (Hancornia speciosa Gomes) growing at Sergipe State, Brazil, was investigated at three different stages. The volatile profile obtained by hydrodistillation, using a Clevenger-type apparatus, was analysed by GC–FID and GC–MS. It was possible to identify 33 compounds in the immature fruits, such as 1-octen-3-ol (2.8%), (Z)-linalool oxide (9.1%), (E)-linalool oxide (6.3%), linalool (16.1%), 2-phenylethanol (4.5%), α-terpineol (5.5%), geraniol (3.1%), hexadecanal (2.5%) and octadecanol (2.7%); 34 compounds in the fruits at the intermediate stage, such as ethyl propanoate (4.1%), n-propyl acetate (11.1%), 3-methyl-3-buten-1-ol (6.8%), 2-methyl propyl acetate (2.5%), furfural (18.6%), (Z)-3-hexenol (3.2%), 1-hexanol (2.4%), 3-methyl-3-buten-1-yl acetate (5.4%), (Z)-3-hexen-1-yl acetate (2.9%), n-hexyl acetate (3.3%), (Z)-linalool oxide (3.9%), (E)-linalool oxide (2.4%), linalool (3.8%), 2-phenylethanol (2.8%) and α-terpineol (2.5%); and 32 components in the mature fruits, such as 3-hydroxy-2-butanone (9.1%), 2,4,5-trimethyl-1,3-dioxolane (6.8%), 3-methyl-3-buten-1-ol (12.1%), 3-methyl-1-butanol (5.2%), furfural (8.3%), 3-methyl-1-butanyl acetate (8.8%) and 3-methyl-3-buten-1-yl acetate (28.2%).     

Heterosis for meat quality and fatty acid profiles in crosses among Bos indicus and Bos taurus finished on pasture or grain

Physicochemical properties and fatty acid profiles of meat from Bos indicus, Bos taurus and crossbred B. taurus × B. indicus bullocks (n = 216), finished on pasture or grain, were used to estimate the effects of heterosis. Meat quality and fatty acid profiles generally benefited with crossbreeding, but the advantages from heterosis differed among finishing systems. The Warner–Bratzler shear-force in fresh and aged meat was reduced due to heterosis in pasture-finishing, but the effect was minor under grain-finishing. With pasture-finishing, heterosis caused an increase of 5% in CLA concentration, but few other changes in fatty acid profiles. In grain-finishing, heterosis caused a reduction in intramuscular fat and cholesterol, increased amounts of PUFA, n− 6 fatty acids and PUFA/SFA ratio, and a decline in atherogenic index. The Δ⁹ desaturase estimated activity in crossbreds showed a behavior close to B. indicus, suggesting the existence of few loci and a dominance genetic effect on enzymes involved in fatty acid synthesis and metabolism.     

Application of a dot blot hybridization assay for genotyping Streptococcus uberis from Brazilian dairy herds

Streptococcus uberis is a major cause of environmental mastitis in many regions, and it is associated with clinical and subclinical infections. Although the main source of infection is the environment, reports of strains with a contagious profile have been described. Dot blot hybridization analysis allows the rapid identification of S. uberis population structures within and between herds, and it helps to identify strain diversity as well as possible clonal lineages that directly affect the control of bovine mastitis caused by this pathogen. The aim of this study was to evaluate the diversity of S. uberis isolates obtained from clinical (n = 22) and subclinical (n = 22) cases of mastitis in dairy herds (n = 13) in Brazil over a period of 12 mo. We submitted 44 S. uberis isolates to dot blot hybridization followed by automatic data analysis. We identified 8 different hybridization patterns using genetic markers associated with virulence factors and taxonomy, indicating diversity of S. uberis within the population and suggesting environmental transmission. However, the evidence of identical dot blot patterns in different mammary quarters from the same animal also suggested local contagious transmission. Of the virulence genes evaluated, we found a high prevalence of the genes sua, pauA, and gapC, highlighting the importance of these virulence factors for the adhesion, invasion, and multiplication of S. uberis in subclinical and clinical intramammary infections.     

Silicon sheet from silane: first results

A process to obtain self-supported thin silicon films is being developed. Films are grown by optical chemical vapour deposition (CVD) (using halogen lamps as heating system) from silane, at low temperature and relatively high growth rates, on silicon substrates with a sacrificial layer of porous Si (PS), which allows film detachment. The PS layer was formed by anodisation of the Si-substrate surface in a HF:ethanol solution. Film deposition was carried out in an optical cold wall horizontal CVD reactor, operating at atmospheric pressure, and specially designed for this study. Deposition rates and film morphology were studied as a function of substrate nominal temperature, gas concentration and flux. In the final chosen conditions, deposition occurs at a nominal temperature of 840°C, with a silicon growth rate between 2 and 4 μm/min, which is relatively high for the low temperature used. A good usage of silane gas was already achieved, with 80–85% of the silicon in the silane gas being deposited on a 40×40 mm² substrate, with very low deposition rate on the reactor wall. Films of thicknesses from 10 to 150 μm were deposited. The films were found to be continuous with surfaces coated with whiskers. Film detachment from multicrystalline substrates has proved unsuccessful so far, while it readily occurs when monocrystalline substrates are used. The reason for this is macropore collapse and film rupture, usually occurring in the smaller grain regions of the multicrystalline substrates.