Testes de estresse na avaliação do vigor de sementes de milho

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

New flexible and transparent solution-based germanium-sulfide polymeric materials

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Implementing new northernmost records to modelling the distribution of Hypsiboas caingua (Anura: Hylidae) in South America

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Dielectric properties of Sr0.75Ba0.25Nb 2O6 thin films: Bias field, frequency and temperature dependence

Ferroelectric strontium barium niobate solid solutions had received great attention due to their excellent pyroelectric, electrooptic and photorefractive properties. Furthermore, they usually also present very interesting phase transition characteristics. In this work, polycrystalline single phase Sr 0.75 Ba 0.25 Nb 2 O 6 thin films were prepared by a hybrid chemical method and deposited on Pt/Ti/SiO 2 /Si substrates. The temperature dependence of dielectric constant was measured at different frequencies and bias field levels. The presence of two dielectric dispersion regions with relaxor characteristics was observed at distinct temperature ranges, corresponding to the ferro-paraelectric and to a structural phase transition at low temperatures, respectively. A specific dielectric dispersion region, associated with an incommensurate superstructure frequently observed in bulk samples, was not observed in this films probably due to their small grain sizes. © 2002 Taylor & Francis.

Artifactual oxidation of cholesterol during the analysis of cholesterol oxidation products: protective effect of antioxidants

To study the influence of the addition of various antioxidants and their combinations on the artifactual oxidation of cholesterol during analysis, 2 factorial experiments were performed in duplicate. In the first experiment, 2 amounts of the following antioxidants were assayed: ethylenediaminetetraacetic acid (EDTA) disodium salt (0 and 1 mg), pyrogallol (0 and 600 microg), and butylated hydroxytoluene (BHT; 0 and 600 microg); in the second, EDTA disodium salt (0 and 1 mg), ascorbyl palmitate (0 and 600 microg), and BHT (0 and 600 microg). Under low oxidative conditions of dim light, evaporation of solvents at low temperatures, and cold saponification in darkness under nitrogen atmosphere, the addition of antioxidants showed no further protective effect. Furthermore, the presence of ascorbyl palmitate significantly increased the formation of cholesterol-5beta,6beta-epoxide, and 7beta-hydroxycholesterol.

Propriedades ópticas de nanopartículas de halogenetos de cobre preparadas in situ em filmes híbridos de sílica

The sol-gel process is a technique based on the hydrolysis and polycondensation of metal alkoxides have been investigated as an alternative for the preparation of vitreous or glassceramic materials, for allowing the obtaining of high-purity materials at low temperatures, and to obtain hybrid materials with different compositions. When ORMOSILs are doped with nanoparticles, are called nanocomposites, and its functionality arises when electrons confined in scale three-dimensional structures near zero are excited. In principle, such materials exhibit discrete energy level, with peaks in the absorption spectrum. Therefore, the glasses doped semiconductor nanocrystals are important candidates for the preparation of optical filters with sharp cut-off, and are being exploited commercially for coloring glasses. This study evaluates the optical properties presented by hybrid films of silica doped with copper nanoparticles. The matrix was prepared using the alkoxides 3-glycidoxypropyltrimethoxysilane (GPTS) and tetraethylorthosilicate (TEOS) doped with Cu2O and hydrolyzed under reflux conditions in two different acidic conditions (HCl and HBr). After thermal treatment at temperatures between 100 °C and 170 °C and/or under the action of commercial black light radiation, CuCl and CuBr present in the hybrid film are transformed into nanoparticles of CuCl or CuBr. The UV-VIS absorption identified the absorption bands, and its variation

Determinação de sólidos solúveis e firmeza em frutos íntegros de pessegueiro por meio da espectroscopia do infravermelho próximo (NIR)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise dos métodos de leira estática e de revolvimento manual na compostagem de resíduos orgânicos gerados em restaurante universitário

Composting is considered a process that enables adding value to organic solid waste turning them into organic fertilizer. In this process, factors such as mishandling the windrow, failed to control the temperature, aeration and moisture content will result in the quality of waste decomposition, and thus affect the quality of the final compound. Decentralized systems such as home composting, composting in restaurants, food courts and schools are one of the solutions for valuing these waste in a non expensive way and with greater quality. For this purpose, the project aims to analyze the conditions for composting of solid waste of the University Restaurant of Rio Claro- SP, through two different composting systems: manual revolving windrow and static pile. It was found that in University Restaurant (RU) on average 33% by weight of the total waste generated in the property are capable of composting. In this sense, in order to investigate the preliminary process operation parameters were mounted one manual windrow composed of 100% of the UR waste and a static pile composed of 60% of the UR waste and 40% of pruning and grass residues (PG). This study analyzed the manual revolving windrow and static pile systems for the parameters: moisture content, pH, C / N ratio and temperature. The study of the proportions of the PG and UR waste pointed to the need for pruning and grass residues addition for composting, considering that the manual revolving windrow composed by 100% of the UR waste had no satisfactory performance due to low temperatures measured during 60 days analysis. The best ratio for manual revolving windrow method analyzed in this study was 60% of the UR waste and 40% of PG waste, in dry weight. From this proportion a static pile was assembled, composed of 60% of UR waste e 40% of PG waste from the maintenance activities of the green area of the university. The biological activity in the static pile reached the maximum temperature of ...

Íons terras raras inseridos em matrizes poliméricas de germânio e enxofre para preparação de materiais com propriedades ópticas

Pós-graduação em Química - IQ

Medidas de condutividade A.C. e constante dielétrica na perovskita dupla Ca1.2 La0.8 FeIrO6

This work introduces the results from the performing of impedance spectroscopy on the transition metals oxide Ca1.2La0.8FeIrO6. It was sought to understand the behavior of one sample from its impedance spectra for different AC voltages and temperature values and if an applied external magnetic field at room temperature would cause some change on it. The results revealed that the Ca1.2La0.8FeIrO6 at high temperatures shows conductive and inductive behavior and that the resistance increases with frequency, phenomenon known as Kelvin effect. At 150 K, the spectrum real part no longer consists with the theoretical prediction of Kelvin effect, starting to be influenced by the utilized voltages, condition that inexists on theory. At low temperatures (10, 20, 30 K) it was observed resistive and capacitive behavior, being possible on these conditions, associate to the sample a paralel RC circuit in series with a contact resistance with a fitting from the ZSim software. This fitting allowed the obtaining of capacitance, DC resistance and contact resistance values. The application of a 700G magnetic field at room temperature didn't cause changes on the spectra

Regulation of the abundance and turnover of copepod species by temperature, turbidity and habitat type in a large river basin

Freshwater copepods were sampled in the La Plata River basin to identify the processes that affect beta diversity and to determine the main factors influencing their geographical distribution and patterns of endemism. Beta diversity patterns exhibited strong dissimilarity between locations; the turnover process was predominant and indicated a replacement of species along the basin. Redundancy analysis indicated the presence of two large sets of species separated geographically by a boundary zone, with several associated variables. Northern species were associated with water transparency and temperature, mean air temperature, mean air temperature during winter and minimum air temperature of coldest month, indicating that these species are not tolerant to low temperatures and are abundant in reservoirs that are common in the upper stretch of the Paraná River basin. Southern species were related with amplitude of air temperature, turbidity, total phosphorus and total suspended matter, indicating that these species are polythermic and have adapted to live in river stretches. From 20 environmental variables analyzed in our study, partial least squares analysis indicated four variables with increased retention of effects on copepod abundance: air temperature, minimum temperature of coldest month, turbidity and transparency. Because almost all of the species found in this study occurred across a wide range of habitat types, the cause of the separation between river and reservoir species could be considered to be more anthropogenic than natural, and it primarily affected species abundance. For certain members of the northern group of copepod species, distribution was dependent on high temperatures, whereas the distribution of the southern group indicated that the species were polythermic.

Análise de um trocador de calor tipo serpentina de uma planta de hipoclorito de sódio

This study aims to analyze the capacity of a helical coil heat exchanger to reach the requested heat transfer rates by a sodium hypochlorite production process. This heat exchanger was installed in an experimental way in order to reuse a source of low-temperatures water in such a way to become a more economical alternative than the existing cooling tower. Firstly, the concepts related to the theory of heat transfer applicable to the case were introduced. Then, the mapping of the main information about the production process and the technical specification of the current cooling system equipment's was realized. Using the dimensions of the heat exchanger installed today as reference, the calculations for determining the ideal length of the coil to different flows of hot fluid were performed. Finally, it was concluded that the heat exchanger currently employed does not provide heat transfer rates required for the maximum flow rate value supported by the cooling tower

Structural and Magnetic Properties of Neodymium - Iron - Boron Clusters

Using inert gas condensation techniques the properties of sputtered neodymium-iron-born clusters were investigated. A D.C. magnetron sputtering source created vaporous Nd-Fe-B which was then condensed into clusters and deposited onto silicon substrates. A composite target of Nd-Fe-B discs on an iron plate and a composite target of Nd-(Fe-Co)-B were utilized to create clusters. The clusters were coated with a carbon layer through R.F. sputtering to prevent oxidation. Samples were investigated in the TEM and showed a size distribution with an average particle diameter of 8.11 nm. The clusters, upon deposition, were amorphous as indicated by diffuse diffraction patterns obtained through SAD. The EDS showed compositionally a direct correlation in the ratio of rare-earth to transition metals between the target and deposited samples. The magnetic properties of the as-deposited clusters showed superparamagnetic properties at high temperatures and ferromagnetic properties at low temperatures; these properties are indicative of rare-earth transition metal amorphous clusters. Annealing of samples showed an initial increase in the coercivity. Samples were annealed in an inert gas atmosphere at 600o C for increasing amounts of time. The samples showed an initial increase in coercivity, but showed no additional increases with additional annealing time. SAD of annealed cluster samples showed the presence of Nd2Fe17 and a bcc-Nd phase. The bcc-Nd is the result of oxidation at high temperatures created during annealing and surface interface energy. The magnetic properties of the annealed samples showed weak coercivity and a saturation magnetization equivalent to that of Nd2Fe17. The annealed clusters showed a slight increase in coercivity at low temperatures. These results indicate a loss of boron during the sputtering process.

DEVELOPMENTAL STATUS OF N-(3-CHLORO-4-METHYLPHENYL) ACETAMIDE AS A CANDIDATE BLACKBIRD/STARLING ROOST TOXICANT

Large winter roosts of blackbirds (Icteridae) and starlings (Sturnus vulgaris) often cause conflicts, both real and imagined, between the birds and local human popula- tions. These conflicts may range from objections to the noise and odor engendered by thousands or millions of birds, to fear of epidemic human and livestock diseases, and the possibility of economic losses from crop depredations. Many people believe the most direct way to combat these conflicts is to reduce local roosting populations by kill- ing the birds. In response to this perceived need for a roost toxicant, the U.S. Fish and Wildlife Service (FWS) developed PA-14, a surfactant which can be aerially applied to problem roosts for population reduction (Lefebvre and Seubert 1970). Successful use of this material, however, requires concurrent rainfall and low temperatures, conditions which may not occur sufficiently often to permit roost treatment at desired times or places. Because of this difficulty, and continued pressures from management person- nel and the agricultural community, the Service has continued its search for a safe, ef- fective roost toxicant usable without severe weather restrictions. One of the current candidate materials is N-(3-chloro-4-methylphenyl)acetamide (CAT, DRC-2698), a derivative of StarlicideR (DRC-1339). This compound was initially developed by S.A. Peoples of the University of California-Davis (Peoples et al. 1976). California researchers are still investigating the avicidal potential of CAT, mainly on baits and in wick perches, while FWS interest has centered thus far on its possible utility as an aerially applied roost treatment. This report is a summary of our investigations to date.

Análise de um trocador de calor tipo serpentina de uma planta de hipoclorito de sódio

This study aims to analyze the capacity of a helical coil heat exchanger to reach the requested heat transfer rates by a sodium hypochlorite production process. This heat exchanger was installed in an experimental way in order to reuse a source of low-temperatures water in such a way to become a more economical alternative than the existing cooling tower. Firstly, the concepts related to the theory of heat transfer applicable to the case were introduced. Then, the mapping of the main information about the production process and the technical specification of the current cooling system equipment's was realized. Using the dimensions of the heat exchanger installed today as reference, the calculations for determining the ideal length of the coil to different flows of hot fluid were performed. Finally, it was concluded that the heat exchanger currently employed does not provide heat transfer rates required for the maximum flow rate value supported by the cooling tower