Perda de nutrientes por escoamento superficial em microbacias do Nordeste paraense sob uso agrícola.

Uma das etapas do ciclo hidrológico refere-se à água da chuva que precipita sobre um ecossistema terrestre entra em contato com a superfície vegetal ou cai diretamente sobre a superfície do solo. Já no solo, a água pode evaporar ou compor a solução do solo, disponibilizando os nutrientes para os vegetais e microrganismos. Por sua vez, a água que escoa na superfície do terreno em direção aos cursos d?água, processo denominado escoamento superficial, carreia os nutrientes presentes no solo para os recursos hídricos, o que é de fundamental importância para a biota aquáticae para a qualidade da água. Portanto, as propriedades do solo influenciam na transferência desses nutrientes para o ecossistema aquático. Assim, alterações sobre o ecossistema provocadas pelo homem podem alterar parte do ciclo hidrológico quanto à quantidade e qualidade da água. Nesse contexto, apresenta-se a etapa prévia do projeto em questão, a qual foi reconhecer e definir as microbacias onde será realizada a pesquisa, realizar treinamento de campo e laboratório, e iniciar levantamento bibliográfico

Low-field microwave absorption and magnetoresistance in iron nanostructures grown by electrodeposition on n-type lightly-doped silicon substrates

In this study we investigate magnetic properties, surface morphology and crystal structure in iron nanoclusters electrodeposited on lightly-doped (100) n-type silicon substrates. Our goal is to investigate the spin injection and detection in the Fe/Si lateral structures. The samples obtained under electric percolation were characterized by magnetoresistive and magnetic resonance measurements with cycling the sweeping applied field in order to understand the spin dynamics in the as-produced samples. The observed hysteresis in the magnetic resonance spectra, plus the presence of a broad peak in the non-saturated regime confirming the low field microwave absorption (LFMA), were correlated to the peaks and slopes found in the magnetoresistance curves. The results suggest long range spin injection and detection in low resistive silicon and the magnetic resonance technique is herein introduced as a promising tool for analysis of electric contactless magnetoresistive samples.Comment: 12 pages, 5 figure

Effect of a nuclear polyhedrosis virus on Spodoptera frugiperda (Smith) (Lepidoptera:noctuidae) larvae, its damage and yield of maize crop.

The efficiency of Baculovirus in a wettable powder formulation to control the fall armyworm Spodoptera frugiperda (Smith) was evaluated using variations of the recommended dose of 50 grams per hectare (2.5 x 1011 polyhedron inclusion bodies - PIB ha-1): 50 or 100 g ha-1 applied once, and variations of two applications at seven-day intervals, of 25+25, 25 + 50, 50+25 and 50+50 g ha-1, compared to untreated plots. The treatments were arranged in a randomized complete block design with six replications. Each plant at 6-8 or 8-10-leaf growth stages, was artificially infested with 10 newly hatched larvae. The virus suspension (300 L ha-1) was applied 24 hours after larvae infestation using a back-pack-manual sprayer at 40 PSI (2.8 kg cm-2) and a regular flat fan nozzle. Larval mortality rate obtained from plots with the application of 50 g of Baculovirus wettable formulation ha-1, at once (96.2%), was significantly higher than that obtained with the application of 25+25 g ha-1 (85.3%) or 25 + 50 g ha-1 (87.8%). However, it was lower than that obtained from the other virus treatments, which had no significant difference among them (mean of 99.2%). The damage caused by S. frugiperda on the leaves of plants of untreated plots (average of 4.5 in an visual scale from 1 to 5) was significantly different from that observed in plots sprayed with virus (1.75 to 2.33). Plants protected with the virus produced significantly higher yield (mean of 7,577 kg ha-1) than plants unprotected (6,140 kg ha-1), that is, 23.4% higher