Structural and magnetic properties of CoFe2O4 thin films deposited by laser ablation on Si (001) substrates

Cobalt ferrite (CoFe(2)O(4)) thin films have been deposited on Si (001) substrates, with different substrate ternperatures (Td,p = 25 degrees C - 600 degrees C). The films were prepared by pulsed laser ablation with a KrF excimer laser (wavelength lambda = 248 nm). The oxygen pressure during deposition was 2 x 10(-2) mbar. The films structure was studied by X-ray diffraction (XRD) and their surface was examined by scanning electron microscopy (SEM). The magnetic properties were measured with a vibrating sample magnetometer (VSM). For low deposition temperatures, the films presented a mixture ofa CoFe(2)O(4) phase, with the cubic spinel structure, and cobalt and iron antiferromagnet oxides with CoO and FeO stoichiometries. As the deposition temperature increased, the CoO and FeO relative content strongly decreased, so that for Tdep = 600 degrees C the films were composed mainly by polycrystalline CoFe(2)O(4). The magnetic hysteresis cycles measured in the films were horizontally shifted due to an exchange coupling field (H(exch)) originated by the presence of the antiferromagnetic phases. The exchange field decreased with increasing deposition temperature, and was accompanied by a corresponding increase of the coercivity and remanence ratio of the cycles. This behavior was due to the strong reduction of the CoO and FeO content, and to the corresponding dominance of the CoFe(2)O(4) phase on the magnetic properties of the thin films.This work has been financially supported by the Portuguese Foundation for Science and Technology (FCT), through the project POCI/CTM/60181/2004

Using the Sound Card as a Timer

Experiments in mechanics can often be timed by the sounds they produce. In such cases, digital audio recordings provide a simple way of measuring time intervals with an accuracy comparable to that of photogate timers. We illustrate this with an experiment in the physics of sports: to measure the speed of a hard-kicked soccer ball.Comment: 3 pages, 4 figures, Late

Reação de genótipos de abóbora a Phytophthora capsici.

O objetivo deste trabalho foi avaliar a reação de 30 genótipos de abóbora (acessos, linhagens e cultivares comerciais) a Phytophthora capsici Leonian. Como testemunhas utilizou-se pimentão ?Casca Dura Ikeda?.Resumo 19

Sensitivity curves for spaceborne gravitational wave interferometers

To determine whether particular sources of gravitational radiation will be detectable by a specific gravitational wave detector, it is necessary to know the sensitivity limits of the instrument. These instrumental sensitivities are often depicted (after averaging over source position and polarization) by graphing the minimal values of the gravitational wave amplitude detectable by the instrument versus the frequency of the gravitational wave. This paper describes in detail how to compute such a sensitivity curve given a set of specifications for a spaceborne laser interferometer gravitational wave observatory. Minor errors in the prior literature are corrected, and the first (mostly) analytic calculation of the gravitational wave transfer function is presented. Example sensitivity curve calculations are presented for the proposed LISA interferometer. We find that previous treatments of LISA have underestimated its sensitivity by a factor of $\sqrt{3}$.Comment: 27 pages + 5 figures, REVTeX, accepted for publication in Phys Rev D; Update reflects referees comments, figure 3 clarified, figure 5 corrected for LISA baselin

Alterações antrópicas em áreas de remanescentes de vegetação nativa nos municípios certificados pelo projeto "Municípios Verde Azul" no Estado de São Paulo.

According to the Native Vegetation Forest Inventory of 2010 for São Paulo State the remanescents of natural vegetation (RVN) represent 17.5% of the original native vegetation estimated as being 4,343,000 ha. The RNV are important refuges for animal wildlife and they also function as pockets to moderate temperature and humidity. For society they can be used as parks and also serve as an excellent natural laboratory for environmental education. In 2007, the State Government of São Paulo started a project named "Município Verde Azul? to promote environmental sustainability in municipalities of São Paulo State in which the RVN should be protected. This study aims to monitor areas of anthropogenic changes in RVN of 37 municipalities of São Paulo State that were certified in both years 2008 and 2009. The RVN were monitored using remote sensing images acquired from April to September of 2010. Results showed that RVN were altered in 13 municipalities corresponding to an area of 216 ha which corresponds to 0,39% of the total area of the RVN analyzed in the 37 municipalities

Avaliação da produtividade de girassol semeado em janeiro em Pelotas - RS.

Com o objetivo de avaliar a produtividade de girassol foram realizados dois experimentos na safrinha, experimento 1 (2008) e experimento 2 (2009). Os experimentos foram conduzidos na área experimental da Embrapa Clima Temperado, com delineamento experimental em blocos casualizados com quatro repetições. A produtividade média do experimento 1 foi de 1190 kg.ha-1, onde foram avaliados os genótipos: Agrobel 960, Aguará 3, Embrapa 122, BRHS 01, Hélio 358 e M 733.No experimento 2, onde foram avaliados os genótipos Agrobel 962, Aguará 4, BRHS 01, Hélio 251, MG 2, Olisum 3 e Zenit, obteve-se produtividade média de 379 kg.ha-1. A diferença na produtividade média entre os experimentos, foi devida as diferentes condições climáticas ocorridas durante a execução dos dois experimentos, principalmente após a floração na fase de enchimento de aquênio, onde as precipitações ocorridas nessa fase foram diferentes, com 4,8 mm no experimento 2 ( 2009) e 135,9 mm no experimento 1 (2008)

Emissão de CO2 em culturas de soja e arroz irrigado - Safra 2013/2014 - RS.

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A Review on Geotrichum Lipases: Production, Purification, Immobilization and Applications

Lipases are enzymes produced from innumerous microorganisms, plants and animal cells. They catalyze reactions of different lipid sources. The Geotrichum fungi are good producers of lipases with high hydrolytic activity and specificity for unsaturated fatty acids. A great number of studies have reported the importance of lipase from this genus and described important fermentation parameters for the enzyme production, such as nutrients, temperature, pH, inoculum, time of fermentation and others. Furthermore, different strategies have been used to purify and immobilize lipases from Geotrichum and innumerous applications are cited in different processes as polyunsaturated fatty acids enrichment, hydrolysis and esterification of fat and oils, synthesis of aromas, biodiesel, and many others. This review highlights fundamental aspects of the production, purification, characterization, immobilization, and the applications of lipases produced by the genus Geotrichum