Influência do oxalato de amônio na formação do precursor columbita obtido pelo método Pechini

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito da densidade de plantas de Bracharia decumbens Stapf sobre o crescimento inicial de mudas de Eucalyptus grandis W. Hill ex Maiden

In order to verify the effect of Brachiaria decumbens plant density on the initial growth of Eucalyptus grandis plants, one assay was conducted under semi-controlled conditions of soil fertility and humidity. Dark red Latossol, collected from the arable layer, was used as substrate in 50 liters amianthus cement boxes. One seedling of Eucalyptus was planted in each box. Fifteen days later, seedlings of B. decumbens were transplanted on the same box. The treatments consisted of 0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 60, 80, 100, and 120 plants of B. decumbens. The experimental design was the complete randomized design, with 15 treatments and four replicates. The Eucalyptus plants that lived with B. decumbens were evaluated for stem diameter, plant high, leaf area, and dry weight of stem, branches and leaves. B. decumbens plants were evaluated for dry weight of aerial parts. B. decumbens, at the density level of four plants per m 2 and over, reduced of the initial growth of the Eucalyptus plants. B. decumbens reduced on average 27.78% stem diameter, 18.47% plant high, 70.56% leaf number, 63.26% leaf area, and 55.22%, 77.29% and 55.30% of stem, branch and leaf dry weight, respectively. Plant high was not a good parameter to evaluate the B. decumbens interference.

Thermodynamic analysis of direct steam reforming of ethanol in molten carbonate fuel cell

Fuel cell as MCFC (molten carbonate fuel cell) operate at high temperatures, and due to this issue, cogeneration processes may be performed, sending heat for own process or other purposes as steam generation in an industry. The use of ethanol for this purpose is one of the best options because this is a renewable and less environmentally offensive fuel, and cheaper than oil-derived hydrocarbons (in the case of Brazil). In the same country, because of technical, environmental and economic advantages, the use of ethanol by steam reforming process have been the most investigated process. The objective of this study is to show a thermodynamic analysis of steam reforming of ethanol, to determine the best thermodynamic conditions where are produced the highest volumes of products, making possible a higher production of energy, that is, a most-efficient use of resources. To attain this objective, mass and energy balances are performed. Equilibrium constants and advance degrees are calculated to get the best thermodynamic conditions to attain higher reforming efficiency and, hence, higher electric efficiency, using the Nernst equation. The advance degree of reforming increases when the operation temperature also increases and when the operation pressure decreases. But at atmospheric pressure (1 atm), the advance degree tends to the stability in temperatures above 700°C, that is, the volume of supplemental production of reforming products is very small for the high use of energy resources necessary. Reactants and products of the steam-reforming of ethanol that weren't used may be used for the reforming. The use of non-used ethanol is also suggested for heating of reactants before reforming. The results show the behavior of MCFC. The current density, at same tension, is higher at 700°C than other studied temperatures as 600 and 650°C. This fact occurs due to smaller use of hydrogen at lower temperatures that varies between 46.8 and 58.9% in temperatures between 600 and 700°C. The higher calculated current density is 280 mA/cm 2. The power density increases when the volume of ethanol to be used also increases due to higher production of hydrogen. The highest produced power at 190 mW/cm 2 is 99.8, 109.8 and 113.7 mW/cm2 for 873, 923 and 973K, respectively. The thermodynamic efficiency has the objective to show the connection among operational conditions and energetic factors, which are some parameters that describes a process of internal steam reforming of ethanol.

Defect-induced photoluminescence of powdered silica glass

Visible photoluminescence was generated in standard soda-lime-silica glass powder, mechanically milled in a high-energy attrition mill. The broad emission band maximum shows a linear dependence on the exciting wavelength, suggesting the possibility to tune the PL emission. The photoluminescence was attributed to defect generation related to unsatisfied chemical bonds due to the high surface area. Raman scattering and ultraviolet-visible optical reflectance measurements corroborate this assertion. Transmission electron microscopy measurements indicate that the powder is composed by nanocrystallites with about 10-20 nanometers immersed in an amorphous media.

Concentration of Cu(II) and Cd(II) from natural river water by Adsorption on a Modified Silica Surface

A high surface area silica gel (737 ± m2 g-1) was synthesized modified through a two-step reaction with a 4-amino-2-mercaptopyrimidine ligand and applied to Cu(II) and Cd(II) adsorption from an aqueous medium. The modified material was characterized by FTIR, which showed that attachment of the molecule occurred via thiol groups at 2547 and 2600 cm-1, and by elemental analysis that indicated the presence of 0.0102 mmol of ligand. The data from adsorption experiments were adjusted to a modified Langmuir equation and the maximum adsorption capacity was 6.6 and 3.8 μmol g-1 for Cu(II) and Cd(II), respectively. After adjusting several parameters, the material was applied in the preconcentration of natural river water using a continuous flow system before and after sample mineralization, and the results showed a 10-fold enrichment factor. The proposed method was validated through preconcentration and analysis of certified standard reference material (1643e), whose results were in agreement with the values provided by the manufacturer.

Preparação e caracterização estrutural e elétrica de células solares sensibilizadas por corantes empregando anodos nanoestruturados à base de 'TiO IND. 2'

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Catalisadores trimetálicos nanoestruturados a base de PtRu para oxidação de metanol

Pós-graduação em Química - IQ

Estudo das propriedades de eletrocatalisadores de Pt-Ru nanoparticulados preparados via microemulsão para oxidação de metanol

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Doses de composto orgânico na produção de chicória e rabanete

Pós-graduação em Agronomia (Horticultura) - FCA

Análise florística, fitossociológica e qualitativa da arborização na Praça XV de Novembro em Ribeirão Preto, SP

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A vulnerabilidade no esporte e a exposição às novas mídias: um estudo sobre o twitter

Pós-graduação em Desenvolvimento Humano e Tecnologias - IBRC

Épocas e densidades de semeadura para os cultivares IAC 18 e IAC 22 de soja Glycine max (L.) Merril na região Sudoeste do Estado de São Paulo

Pós-graduação em Agronomia (Agricultura) - FCA

Espumas cerâmicas produzidas pela conjugação dos processos sol-gel, aeração e emulsificação

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Exumação tectônica e evolução associada do relevo no arco de Ponta Grossa, sul-sudeste do Brasil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Características de substratos e concentrações de soluções nutritivas para o cultivo do crisântemo em vaso

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)