Influence of summertime mesoscale convective systems on the heat balance and surface mixed layer dynamics of a large Amazonian hydroelectric reservoir

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A comparison of global estimates of marine primary production from ocean color

The third primary production algorithm round robin (PPARR3) compares output from 24 models that estimate depth-integrated primary production from satellite measurements of ocean color, as well as seven general circulation models (GCMs) coupled with ecosystem or biogeochemical models. Here we compare the global primary production fields corresponding to eight months of 1998 and 1999 as estimated from common input fields of photosynthetically-available radiation (PAR), sea-surface temperature (SST), mixed-layer depth, and chlorophyll concentration. We also quantify the sensitivity of the ocean-color-based models to perturbations in their input variables. The pair-wise correlation between ocean-color models was used to cluster them into groups or related output, which reflect the regions and environmental conditions under which they respond differently. The groups do not follow model complexity with regards to wavelength or depth dependence, though they are related to the manner in which temperature is used to parameterize photosynthesis. Global average PP varies by a factor of two between models. The models diverged the most for the Southern Ocean, SST under 10 degrees C, and chlorophyll concentration exceeding 1 mg Chlm(-3). Based on the conditions under which the model results diverge most, we conclude that current ocean-color-based models are challenged by high-nutrient low-chlorophyll conditions, and extreme temperatures or chlorophyll concentrations. The GCM-based models predict comparable primary production to those based on ocean color: they estimate higher values in the Southern Ocean, at low SST, and in the equatorial band, while they estimate lower values in eutrophic regions (probably because the area of high chlorophyll concentrations is smaller in the GCMs). Further progress in primary production modeling requires improved understanding of the effect of temperature on photosynthesis and better parameterization of the maximum photosynthetic rate. (c) 2006 Elsevier Ltd. All rights reserved.

Nitrogênio e potássio em bananeira via fertirrigação e adubação convencional-atributos químicos do solo

Realizou-se um experimento em Pindorama (SP), no qual se avaliaram os efeitos da fertirrigação e da adubação convencional com N e K em alguns atributos químicos de solo sob cultivo com bananeira, durante dois ciclos de produção. Avaliaram-se a disponibilidade e a movimentação de nutrientes (P, K, Ca e Mg) no perfil do solo, bem como outros atributos químicos (matéria orgânica, acidez e saturação por bases), por meio de amostragens realizadas na implantação do experimento e ao final do primeiro e segundo ciclos de produção. Os principais efeitos dos tratamentos foram no pH do solo e no teor de K+ trocável. A adubação, tanto aplicada via fertirrigação como na forma convencional, implicou incrementos na acidez do solo, principalmente até 20 cm de profundidade. Observou-se que o impacto da adubação via fertirrigação no pH do solo foi proporcional à dose. A adubação convencional também causou decréscimo no pH, especialmente na região mais próxima das plantas, refletindo o efeito da aplicação localizada dos fertilizantes. A aplicação de adubo sólido na superfície do solo determinou significativo acúmulo de K nas camadas até 20 cm e na região mais próxima ao pseudocaule das plantas. Os efeitos da adubação via fertirrigação foram mais difusos, visto que os adubos são espalhados numa área de solo maior do que a coberta pela adubação convencional.

Distribuição espacial em pequena escala de um anfípode exótico em fragmento florestal e plantio de espécies nativas

Anthropogenic interferences in natural environments cause the breakage of spatial and competitive barriers, which may infuence the spatial distribution of species. In this study, we describe the spatial distribution of an exotic amphipod, Talitroides topitotum, in two distinct sites, a forest fragment and a plantation of native arboreal species. We analyzed possible variations in this spatial distribution in different periods of the year and verifed whether the vegetation cover and the litter layer depth may explain the distribution pattern of this species. We performed analyses of frequency distribution to determine the pattern of this species spatial distribution, as well as correlation tests to determine the effect of these two variables of habitat structure. The spatial distribution analysis revealed that T. topitotum presents aggregated distribution in both areas, indicating that this species has low environmental demands or that both areas are below a minimum environmental quality threshold. However, even with this similarity, the population in the fragmented site presented a higher index of aggregation when compared with the population of the plantation site. Corroborating previous studies, there was a negative correlation between abundance of T. topitotum and litter layer depth in the plantation site. Studies on invaded habitats can help understand how invasive species occupy new environments and the factors that can infuence their spatial distribution.

Aerosols monitoring in Rio Claro, Brazil: Using lidar and air pollution analyzers

Brazil has an important role in the biomass burning aerosol activity. During the Dry Season (June-September) of 2009 an aerosol profiling campaign was carried out using a backscattering and Raman lidar system in Rio Claro-SP, Brazil (22°23'S and 47°32'W). The main goal of this campaign was to observe the biomass burning aerosol load due to sugarcane crops and also study the air dispersion conditions, planetary boundary and mixed layer daily evolution. In this paper we aim to present the preliminary results of the influence of this type of aerosol over the city of Rio Claro-SP, Brazil and one case study to evaluate the aerosol profile in a biomass burning episode that occurred in July, 2009. On July 15 an intense burning was observed about 300 m away from the lidar location. Throughout the measurements it was observed that the plumes reached up to 900 m, and that there was a time gap between the plumes. The gas analyzers showed a strong influence of this burning as it was noticed in the measurements of CO, NO x and nephelometer, whereas the PM10 did not have due to this burning, possibly because the particulate was deposited further from the emission source, not being detected by the equipment. © Sociedad Española de Óptica.

Efeito do fresamento com alta velocidade de corte na usinabilidade de aços ferríticos com grãos ultrafinos

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

Petrologia aplicada da formação Corumbataí (região de Rio Claro - SP) e produtos cerâmicos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Protective film growth on tin in perchlorate and citric acid electrolytes

Voltammetry has been employed to study the influence of systematic additions of citric acid on the E-I curves of Tin in 0.5 M NaClO4, in order to verify the film growth in the presence of the organic acid and the inhibition of the pitting corrosion of the metal. The minimum concentration of the organic acid needed to change the GI curves is 10(-2) M, in the pH range 1.0-4.0. At pH 3.0 and 4.0, the scan rate dependence on current density, in the potential region of formation and reduction of the film, showed that in a first stage adsorption occurs. In a second stage, the v(1/2) dependence found can he explained by ohmic resistance control. The formation of tin/citric acid complexes, 10(-2) M, is suggested. The pitting inhibition may be due to the formation of a mixed layer of tin in citric acid concentrations higher than 10(-2) oxide and tin citrate complexes on the electrode surface. (C) 2001 Elsevier Science B.V. All rights reserved.

Modelling the surface circulation and thermal structure of a tropical reservoir using three-dimensional hydrodynamic lake model and remote-sensing data

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Redox-tagged peptide for capacitive diagnostic assays

Early detection assays play a key role in the successful treatment of most diseases. Redox capacitive biosensors were recently introduced as a potential electroanalytical assay platform for point-of-care applications but alternative surfaces (besides a mixed layer containing ferrocene and antibody receptive component) for recruiting important clinical biomarkers are still needed. Aiming to develop alternative receptive surfaces for this novel electrochemical biosensing platform, we synthesized a ferrocene redoxtagged peptide capable of self-assembly into metallic interfaces, a potentially useful biological surface functionalization for bedside diagnostic assays. As a proof of concept we used C-reactive protein (CRP), as a model biomarker, and compared the obtained results to those of previously reported capacitive assays. The redox-tagged peptide approach shows a limit of detection of 0.8 nmol L 1 (same as 94 ng mL 1 ) and a linear range (R2 ∼98%) with the logarithm of the concentration of the analyte comprising 0.5–10.0 nmol L 1 , within a clinical relevant range for CRP.