Organic compounds from plant extracts and their effect on soil phosphorus availability

The objective of this work was to evaluate the effect of organic compounds from plant extracts of six species and phosphate fertilization on soil phosphorus availability. Pots of 30 cm height and 5 cm diameter were filled with Typic Hapludox. Each pot constituted a plot of a completely randomized design, in a 7x2 factorial arrangement, with four replicates. Aqueous extracts of black oat (Avena strigosa), radish (Raphanus sativus), corn (Zea mays), millet (Pennisetum glaucum), soybean (Glycine max), sorghum (Sorghum bicolor), and water, as control, were added in each plot, with or without soluble phosphate fertilization. After seven days of incubation, soil samples were taken from soil layers at various depths, and labile, moderately labile and nonlabile P fractions in the soil were analysed. Plant extracts led to an accumulation of inorganic phosphorus in labile and moderately labile fractions, mainly in the soil surface layer (0-5 cm). Radish, with a higher amount of malic acid and higher P content than other species, was the most efficient in increasing soil P availability.

Intercepted solar radiation by maize crops subjected to different tillage systems and water availability levels

The objective of this work was to evaluate changes in the photosynthetic photon flux density (PPFD) interception efficiency and PPFD extinction coefficient for maize crop subjected to different soil tillage systems and water availability levels. Crops were subjected to no-tillage and conventional tillage systems combined with full irrigation and non-irrigation treatments. Continuous measurements of transmitted PPFD on the soil surface and incoming PPFD over the canopy were taken throughout the crop cycle. Leaf area index and soil water potential were also measured during the whole period. Considering a mean value over the maize cycle, intercepted PPFD was higher in the conventional tillage than in the no-tillage system. During the initial stages of plants, intercepted PPFD in the conventional tillage was double the PPFD interception in the no-tillage treatment. However, those differences were reduced up to the maximum leaf area index, close to tasseling stage. The lowest interception of PPFD occurred in the conventional tillage during the reproductive period, as leaf senescence progressed. Over the entire crop cycle, the interception of PPFD by the non-irrigated plants was about 20% lower than by the irrigated plants. The no-tillage system reduced the extinction coefficient for PPFD, which may have allowed a higher penetration of solar radiation into the canopy

Multispectral remote sensing for site-specific nitrogen fertilizer management

The objective of this work was to evaluate the use of multispectral remote sensing for site-specific nitrogen fertilizer management. Satellite imagery from the advanced spaceborne thermal emission and reflection radiometer (Aster) was acquired in a 23 ha corn-planted area in Iran. For the collection of field samples, a total of 53 pixels were selected by systematic randomized sampling. The total nitrogen content in corn leaf tissues in these pixels was evaluated. To predict corn canopy nitrogen content, different vegetation indices, such as normalized difference vegetation index (NDVI), soil-adjusted vegetation index (Savi), optimized soil-adjusted vegetation index (Osavi), modified chlorophyll absorption ratio index 2 (MCARI2), and modified triangle vegetation index 2 (MTVI2), were investigated. The supervised classification technique using the spectral angle mapper classifier (SAM) was performed to generate a nitrogen fertilization map. The MTVI2 presented the highest correlation (R²=0.87) and is a good predictor of corn canopy nitrogen content in the V13 stage, at 60 days after cultivating. Aster imagery can be used to predict nitrogen status in corn canopy. Classification results indicate three levels of required nitrogen per pixel: low (0-2.5 kg), medium (2.5-3 kg), and high (3-3.3 kg).

Ruzigrass affecting soil-phosphorus availability

The objective of this work was to evaluate the effectiveness of ruzigrass (Urochloaruziziensis) in enhancing soil-P availability in areas fertilized with soluble or reactive rock phosphates. The area had been cropped for five years under no-till, in a system involving soybean, triticale/black-oat, and pearl millet. Previously to the five-year cultivation period, corrective phosphorus fertilization was applied once on soil surface, at 0.0 and 80 kg ha-1 P2O5, as triple superphosphate or Arad rock phosphate. After this five-year period, plots received the same corrective P fertilization as before and ruzigrass was introduced to the cropping system in the stead of the other cover crops. Soil samples were taken (0-10 cm) after ruzigrass cultivation and subjected to soil-P fractionation. Soybean was grown thereafter without P application to seed furrow. Phosphorus availability in plots with ruzigrass was compared to the ones with spontaneous vegetation for two years. Ruzigrass cultivation increased inorganic (resin-extracted) and organic (NaHCO3) soil P, as well as P concentration in soybean leaves, regardless of the P source. However, soybean yield did not increase significantly due to ruzigrass introduction to the cropping system. Soil-P availability did not differ between soluble and reactive P sources. Ruzigrass increases soil-P availability, especially where corrective P fertilization is performed.

Soil nutrient availability and its impact on fruit quality of Tahiti acid lime

The Tahiti acid lime in Brazil is mostly grown in the São Paulo State. The value of this crop production ranks among the ten most important fruits in the country. The Brazilian exports of Tahiti limes have increased in the last years with a corresponding increased demand for superior quality of fresh fruits, which is affected by mineral nutrients. Therefore, this study evaluated nutrient soil availability and its influence on nutritional status of trees based on the determination of leaf and fruit nutrient concentrations, fruit characteristics, and post harvest quality. Eleven commercial groves with trees older than 4-yr and differently managed were studied. Plots with six trees in each grove were sampled for soil (0-20 cm depth layer), leaf and fruit analyses with three replicates. Correlation coefficients were pair wised established for all variables. The results showed that N leaf concentration was well correlated with green color of fruit peel as measured by a color index (r = -0.71**), and which was optimum with Leaf-N around 22 g kg-1. Leaf-Ca was inversely correlated with fruit water loss after 14-day interval from harvest (r = -0.54*) demonstrating that Ca plays an important role in Tahiti fruit shelf-life. Data also suggested that increased fruit K concentration correlated with increased fruit water losses during storage (r >0.58*).

Computed tomography angiography in patients with active gastrointestinal bleeding

Abstract Gastrointestinal bleeding represents a common medical emergency, with considerable morbidity and mortality rates, and a prompt diagnosis is essential for a better prognosis. In such a context, endoscopy is the main diagnostic tool; however, in cases where the gastrointestinal hemorrhage is massive, the exact bleeding site might go undetected. In addition, a trained professional is not always present to perform the procedure. In an emergency setting, optical colonoscopy presents limitations connected with the absence of bowel preparation, so most of the small bowel cannot be assessed. Scintigraphy cannot accurately demonstrate the anatomic location of the bleeding and is not available at emergency settings. The use of capsule endoscopy is inappropriate in the acute setting, particularly in the emergency department at night, and is a highly expensive method. Digital angiography, despite its high sensitivity, is invasive, presents catheterization-related risks, in addition to its low availability at emergency settings. On the other hand, computed tomography angiography is fast, widely available and minimally invasive, emerging as a promising method in the diagnostic algorithm of these patients, being capable of determining the location and cause of bleeding with high accuracy. Based on a critical literature review and on their own experience, the authors propose a computed tomography angiography protocol to assess the patient with gastrointestinal bleeding.

Determinação da origem biossintética de ácido acético através da técnica "Site Specific Natural Isotopic Fractionation Studied by Nuclear Magnetic Resonance (SNIF-NMR)"

The main purpose of this work is to describe the use of the technique Site-Specific Natural Isotopic Fractionation of hydrogen (SNIF-NMR), using ²H and ¹H NMR spectroscopy, to investigate the biosynthetic origin of acetic acid in commercial samples of Brazilian vinegar. This method is based on the deuterium to hydrogen ratio at a specific position (methyl group) of acetic acid obtained by fermentation, through different biosynthetic mechanisms, which result in different isotopic ratios. We measured the isotopic ratio of vinegars obtained through C3, C4, and CAM biosynthetic mechanisms, blends of C3 and C4 (agrins) and synthetic acetic acid.

Alargamento da distribuição de massa molar de polímeros sintetizados com catalisadores metalocênicos dual-site

The main topics related to the use of dual-site catalysts in the production of polymers with broad molecular weight distribution are reviewed. The polymerization using dual-site catalysts is more economical and allows to produce a higher quality product than other processes, such as polymer blend and multistage reactors. However, the formulation of these catalysts is quite complicated since the same catalyst must produce distinct polymer grades. In addition, the release of patents concerning the combination of metallocenes and new technologies for polymerization shows that polymerization processes using dual-site catalysts are of current industrial interest.

Aerosol particle size distributions at a traffic exposed site and an urban background location in Oporto, Portugal

Aerosol size distributions from 6 to 700 nm were measured simultaneously at an urban background site and a roadside station in Oporto. The particle number concentration was higher at the traffic exposed site, where up to 90% of the size spectrum was dominated by the nucleation mode. Larger aerosol mode diameters were observed in the urban background site possibly due to the coagulation processes or uptake of gases during transport. Factor analysis has shown that road traffic and the neighbour stationary sources localised upwind affect the urban area thought intra-regional pollutant transport.

Effect of metal ions on the in vitro availability of enoxacin, its in vivo implications, kinetic and antibacterial studies

The present paper describes the effect of metals ions on the in vitro availability of enoxacin (a second generation quinolone antibiotic) owing to drug-metal interaction. These interaction studies were performed at 37 °C in different pH environments simulating human body compartments and were studied by UV spectroscopic technique. In order to determine the probability of these reactions different kinetic parameters (dissolution constants (K) and free energy change (ΔG)) for these reactions were also calculated. It is proposed that the structure of enoxacin contains various electron donating sites which facilitate its binding with metallic cations forming chelates. Hence taking food products, nutritional supplements or multivitamins containing multivalent cations at the same time as enoxacin, could reduce the absorption of the drug into the circulation and thus would decrease the effectiveness of the drug. In addition, the MIC of enoxacin for various microorganisms before and after interaction with metal ions was calculated which in most cases was increased which possibly could impair the clinical efficacy of the drug.

Control of Asian soybean rust with mancozeb, a multi-site fungicide

An experiment conducted in the field the action of mancozeb, a fungicide of multi-site action was tested, to control soybean rust caused by Phakopsora pachyrhizi. Its performance was compared to that of the mixture cyproconazole (DMI) + azoxystrobin (QoI). The soybean cultivar NA 7337 RR was used with a population of 400,000 plants/ha cultivated in 20m2 plots. Treatments consisted of mancozeb levels (1.5 and 2.0 kg/ha) applied four, six and eight times. The DMI + QoI mixture was applied three times at 0.3 L/ha + Nimbus. Rust severity was assessed six times in the plots and data were integrated as the area under the disease progress curve (AUDPC). The plots were harvested and grain yield was expressed as kg/ha. Data on AUDPC and yield were subjected to analysis of variance and means compared according to Turkey's test (p = 0.005). Treatments with mancozeb were superior to DMI + QoI mixture both for rust control and grain yield. Four applications of 2.0 k/ha mancozeb were more efficient than three applications of the mixture used as standard. Mancozeb has the potential to be added to fungicide mixtures in the establishment of soybean rust anti-resistance strategy.

Disseminação seletiva da informação na área da saúde: o caso do web site Amedeo

As atividades de produção/divulgação de informações foram otimizadas pela facilidade de comunicação oferecida pela internet, e a produção científica cresce cada vez mais. Com foco nas facilidades de acesso à informação científica oferecidas pela tecnologia, o objetivo é evidenciar os benefícios da aplicação da Disseminação Seletiva da Informação (SDI) na formação de profissionais da saúde, a partir da análise do web site Amedeo. Faz-se um estudo comparativo, de modo a verificar como os artigos disseminados pelo Amedeo podem ser acessados no próprio e numa biblioteca universitária - no caso, analisou-se o acesso através do site do Sistema de Bibliotecas da Unicamp e, ainda, recorre-se à literatura para identificar relações entre a Ciência da Informação e a área de Ciências da Saúde, principalmente quanto à prática da Medicina Baseada em Evidências. Apresentam-se sugestões aos profissionais da informação e professores interessados em identificar possibilidades de uso dos recursos do Amedeo e demais serviços de SDI, em bibliotecas universitárias, de modo a colaborar com o processo educacional dos profissionais da área da saúde.

Dry biomass distribution in a cerrado sensu stricto site in Brazil central

The Cerrado has been the main source of firewood and charcoal in Brazil, but despite being one of the hot spots for conservation of the world's biodiversity, neither plantations of native species nor sustainable management has been adopted in the region. The aim of this work was to investigate the biomass distribution and the potential for energy production of the cerrado species. The study was conducted in a cerrado sensu stricto site at the Água Limpa Farm (15º 56'14'' S and 47º 46'08'' W) in the Cerrado Biosphere Reserve. An area of 63.54ha was divided in 20 x 50m plots and, a random sample consisting of ten of these plots, representing 1.56% of the study-site, was assessed. All woody individuals from 5 cm diameter at 30 cm above ground level were identified and measured. Each individual was felled, the twigs thinner than 3cm were discarded while the larger branches and the trunks, both with bark, were weighted separately. After that, 2.5cm transverse sections of the trunk with bark were taken at 0, 25, 50, 75 and 100% of the length. A similar sample was also taken at the base of each branch. A total of 47 species in 35 genera and 24 families were found, with an average density of 673 individuals per ha. The diameter distribution showed a reversed-J shape with 67% of the individuals up to 13cm, while the maximum diameter was 32.30cm. Seven species represented 72% of the total biomass. In general, the species with higher production per tree were among those with higher production per ha. This content was distributed by diameter classes, reaching a maximum of 2.5ton/ha between 9 to 13cm and then, decreasing to 0.96 ton/ha between 29 to 33cm diameter. Carbon sequestering was 6.2ton/ha (until the actual stage of cerrado) based on an average 50% carbon content in the dry matter. The heat combustion of the wood varied from 18,903kj/kg to 20,888kj/kg with an average of 19,942kj/kg. The smaller diameter classes fix more carbon due to the large number of small plants per ha. But, for a species that reached larger dimensions and contained individuals in all diameter classes, Vochysia thyrsoidea, one can verify an increase in carbon fixation from 1.41 kg/ha in the first class (5 to 9cm) to 138,3kg/ha in the last (25 to 33cm). That indicates that it is possible to select species that reach larger size with a higher capacity of carbon accumulation per plant. The species that reached larger dimensions, with a production per tree above average and had high calorific power values were Dalbergia miscolobium, Pterodon pubescens and Sclerolobium paniculatum. These species have potential for use in fuelwood plantations and sustainable management.

Measurement and simulation of solar radiation availability in relation to the growth of coffee plants in an agroforestry system with rubber trees

Solar radiation is an important factor for plant growth, being its availability to understory crops strongly modified by trees in an Agroforestry System (AFS). Coffee trees (Coffea arabica - cv. Obatã IAC 1669-20) were planted at a 3.4 x 0.9 m spacing inside and aside rows of monocrops of 12 year-old rubber trees (Hevea spp.), in Piracicaba-SP, Brazil (22º42'30" S, 47º38'00" W - altitude: 546m). One-year-old coffee plants exposed to 25; 30; 35; 40; 45; 80; 90; 95 and 100% of the total solar radiation were evaluated according to its biophysical parameters of solar radiation interception and capture. The Goudriaan (1977) adapted by Bernardes et al. (1998) model for radiation attenuation fit well to the measured data. Coffee plants tolerate a decrease in solar radiation availability to 50% without undergoing a reduction on growth and LAI, which was approximately 2m².m-2 under this condition. Further reductions on the availability of solar radiation caused a reduction in LAI (1.5m².m-2), thus poor land cover and solar radiation interception, resulting in growth reduction.

Conservative nutrient use by big-leaf mahogany (Swietenia macrophylla king) planted under contrasting environmental conditions

We analyzed the nutritional composition and isotope ratios (C and N) of big-leaf mahogany (Swietenia macrophylla King) leaves in plantations established on contrasting soils and climates in Central America (State of Quintana Roo, Yucatán, México) and South America (State of Pará, Brazil). The objective was to determine the adaptability of this species to large differences in nutrient availability and rainfall regimes. Nutrient concentrations of leaves and soils were determined spectrophotometrically, and isotope ratios were measured using mass spectrometric techniques.In Pará soils were sandier, and acidic, receiving above 2000 mm of rain, whereas in Quintana Roo soils were predominantly clayey, with neutral to alkaline pH due to the underlying calcareous substrate, with about 1300 mm of rain. Leaf area/weight ratio was similar for both sites, but leaves from Quintana Roo were significantly smaller. Average N and K concentrations of adult leaves were similar, whereas Ca concentration was only slightly lower in Pará in spite of large differences in Ca availability. Leaves from this site had slightly higher P and lower Al concentrations. Differences in water use efficiency as measured by the natural abundance of 13C were negligible, the main effect of lower rainfall in Quintana Roo seemed to be a reduction in leaf area. The N isotope signature (δ15N) was more positive in Pará than in Quintana Roo, suggesting higher denitrification rates in the former. Results reveal a calciotrophic behavior and a remarkable capacity of mahogany to compensate for large differences in soil texture and nutrient availability.