Seasonal changes of leaf Nitrogen content in trees of Amazonian floodplains

In Amazonian floodplains the trees are exposed to extreme flooding of up to 230 days a year. Waterlogging of the roots and stems affects growth and metabolic activity of the trees. An increased leaf fall in the aquatic period and annual increment rings in the wood indicate periodical growth reductions. The present study aims at documenting seasonal changes of metabolism and vitality of adult trees in the annual cycle as expressed by changes of leaf nitrogen content. Leaves of six tree species common in floodplains in Central Amazonia and typical representants of different growth strategies were collected every month between May 1994 and June 1995 in the vicinity of Manaus, Brazil. Mean leaf nitrogen content varied between 1.3% and 3.2% in the non-flooded trees. Three species showed significantly lower Ν content in the flooded period (p=0.05, 0.001, 0.001), the difference ranging 20-25% lower than in the non-flooded period. Two species showed no significant difference while Nectandra amazonum showed 32% more Ν in the flooded season (p=0.001). Leaf nitrogen content was generally high when new leaves were flushed (in the flooded period) and decreased continuously thereafter in all species. Three species showed an additional peak of nitrogen during the first month of the terrestrial phase, in leaves which had flushed earlier, indicating that flooding may disturb nitrogen uptake.

Fertilization and cover crop effects on soil nitrogen and plant nutrition in a young guarana plantation

Fruit tree production is gaining an increasing importance in the central Amazon and elsewhere in the humid tropics, but very little is known about the nutrient dynamics in the soil-plant system. The present study quantified the effects of fertilization and cover cropping with a legume (Pueraria phaseoloides (Roxb.) Benth.) on soil nitrogen (N) dynamics and plant nutrition in a young guarana plantation (Paullinia cupana Kunth. (H.B. and K.) var. sorbilis (Mart.) Ducke) on a highly weathered Xanthic Ferralsol. Large subsoil nitrate (NO3-) accumulation at 0.3-3 m below the guarana plantation indicated N leaching from the topsoil. The NO3- contents to a depth of 2 m were 2.4 times greater between the trees than underneath unfertilized trees (P<0.05). The legume cover crop between the trees increased soil N availability as shown by elevated aerobic N mineralization and lower N immobilization in microbial biomass. The guarana N nutrition and yield did not benefit from the N input by biological fixation of atmospheric N2 by the legume cover (P>0.05). Even without a legume intercrop, large amounts of NO3- were found in the subsoil between unfertilized trees. Subsoil NO3- between the trees could be utilized, however, by fertilized guarana. This can be explained by a more vigorous growth of fertilized trees which had a larger nutrient demand and exploited a larger soil volume. With a legume cover crop, however, more mineral N was available at the topsoil which was leached into the subsoil and consequently accumulated at 0.3-3 m depth. Fertilizer additions of P and K were needed to increase subsoil NO3- use between trees.

From a NoSQL data source to a business intelligence solution: An experiment

We are living in the era of Big Data. A time which is characterized by the continuous creation of vast amounts of data, originated from different sources, and with different formats. First, with the rise of the social networks and, more recently, with the advent of the Internet of Things (IoT), in which everyone and (eventually) everything is linked to the Internet, data with enormous potential for organizations is being continuously generated. In order to be more competitive, organizations want to access and explore all the richness that is present in those data. Indeed, Big Data is only as valuable as the insights organizations gather from it to make better decisions, which is the main goal of Business Intelligence. In this paper we describe an experiment in which data obtained from a NoSQL data source (database technology explicitly developed to deal with the specificities of Big Data) is used to feed a Business Intelligence solution.

Validation of a method to measure light distortion surrounding a source of glare

Our objective was to validate a new device dedicated to measure the light disturbances surrounding bright sources of light under different sources of potential variability. Twenty subjects were involved in the study. Light distortion was measured using an experimental prototype (light distortion analyzer, CEORLab, University of Minho, Portugal) comprising twenty-four LED arrays panel at 2 m. Sources of variability included: intrasession and intersession repeated measures, pupil size (3 versus 6 mm), defocus (þ0.50) correction for the working distance, angular resolution (15 deg versus 30 deg), temporal stimuli presentation, and pupil size. Size, shape, location, and irregularity parameters have been obtained. At a low speed of presentation of the stimuli, changes in angular resolution did not have an effect on the results of the parameters measured. Results did not change with pupil size. Intensity of the central glare source significantly influenced the outcomes. Examination time was reduced by 30% when a 30 deg angular resolution was explored instead of 15 deg. Measurements were fast and repeatable under the same experimental conditions. Size and shape parameters showed the highest consistency, whereas location and irregularity parameters showed lower consistency. The system was sensitive to changes in the intensity of the central glare source but not to pupil changes in this sample of healthy subjects.

Does nitrogen availability have greater control over the formation of tropical heath forests than water stress?A hypothesis based on nitrogen isotope ratios

Global scale analyses of soil and foliage δ15N have found positive relationships between δ15N and ecosystem N loss (suggesting an open N cycle) and a negative relationship between δ15N and water availability. We show here that soils and leaves from tropical heath forests are depleted in 15N relative to 'typical' forests suggesting that they have a tight N cycle and are therefore limited by N rather than by, often suggested, water availability.

The impact of carbon source in Candida albicans virulence: participation of RLM1 in pathogen host interaction

Dissertação de mestrado em Genética Molecular

The influence of nitrogen and oxygen additions on the thermal characteristics of aluminium-based thin films

The ternary aluminium oxynitride (AlNxOy) system offers the possibility to obtain a wide range of properties by tailoring the ratio between pure Al, AlNx and AlOy and therefore opening a significant number of possible applications. In this work the thermal behaviour of AlNxOy thin films was analysed by modulated infrared radiometry (MIRR), taking as reference the binary AlOy and AlNx systems. MIRR is a non-contact and non-destructive thermal wave measurement technique based on the excitation, propagation and detection of temperature oscillations of very small amplitudes. The intended change of the partial pressure of the reactive gas (N2 and/or O2) influenced the target condition and hence the deposition characteristics which, altogether, affected the composition and microstructure of the films. Based on the MIRR measurements and their qualitative and quantitative interpretation, some correlations between the thermal transport properties of the films and their chemical/physical properties have been found. Furthermore, the potential of such technique applied in this oxynitride system, which present a wide range of different physical responses, is also discussed. The experimental results obtained are consistent with those reported in previous works and show a high potential to fulfil the demands needed for the possible applications of the systems studied. They are clearly indicative of an adequate thermal response if this particular thin film system is aimed to be applied in small sensor devices or in electrodes for biosignal acquisition, such as those for electroencephalography or electromyography as it is the case of the main research area that is being developed in the group.

Contribution for a better ecological understanding of the freshwater phase of sea lamprey (Petromyzon marinus) in the Minho River watershed

Dissertação de mestrado em Ecology

A design of experiments to assess phosphorous removal and crystal properties in struvite precipitation of source separated urine using different Mg sources

Supplementary data associated with this article can be found, in the online version, at: http://dx.doi.org/10.1016/j.cej.2016.03.148.

Seleção de microalgas com potencial de produção de biocombustíveis

Dissertação de mestrado em Bioengenharia

Combustion of alternative biomass fuels in a domestic boiler and in a large-scale furnace

Programa Doutoral em Engenharia Mecânica.

Anaerobic oxidation of methane associated with sulfate reduction in a natural freshwater gas source

The occurrence of anaerobic oxidation of methane (AOM) and trace methane oxidation (TMO) was investigated in a freshwater natural gas source. Sediment samples were taken and analyzed for potential electron acceptors coupled to AOM. Long-term incubations with 13C-labeled CH4 (13CH4) and different electron acceptors showed that both AOM and TMO occurred. In most conditions, 13C-labeled CO2 (13CO2) simultaneously increased with methane formation, which is typical for TMO. In the presence of nitrate, neither methane formation nor methane oxidation occurred. Net AOM was measured only with sulfate as electron acceptor. Here, sulfide production occurred simultaneously with 13CO2 production and no methanogenesis occurred, excluding TMO as a possible source for 13CO2 production from 13CH4. Archaeal 16S rRNA gene analysis showed the highest presence of ANME-2a/b (ANaerobic MEthane oxidizing archaea) and AAA (AOM Associated Archaea) sequences in the incubations with methane and sulfate as compared with only methane addition. Higher abundance of ANME-2a/b in incubations with methane and sulfate as compared with only sulfate addition was shown by qPCR analysis. Bacterial 16S rRNA gene analysis showed the presence of sulfate-reducing bacteria belonging to SEEP-SRB1. This is the first report that explicitly shows that AOM is associated with sulfate reduction in an enrichment culture of ANME-2a/b and AAA methanotrophs and SEEP-SRB1 sulfate reducers from a low-saline environment.

Caracterización genética de la cepa Sinorhizobium meliloti 3DOh13 y evaluación de la capacidad fijadora de nitrógeno en alfalfa. Genetic characterization of the strain Sinorhizobium meliloti 3DOh13 and assessment of the capacity to fix nitrogen in alfalfa.

La provincia de Córdoba participa con aproximadamente el 23 por ciento del área total sembrada anualmente con alfalfa en nuestro país y, en los últimos años, se ha incrementado levemente, en contraste con las provincias de Buenos Aires, Santa Fe y Entre Ríos, donde ha decrecido. La inoculación de este cultivo con cepas del género Sinorhizobium ha permitido mejorar su rendimiento en los suelos de la región semiárida. La utilización para la siembra de semillas preinoculadas con microorganismos de origen extranjero, cuya eficiencia y adaptación a las condiciones locales no siempre se conocen, y con escasa capacidad de competencia ante las cepas naturalizadas, trae como consecuencia un bajo establecimiento de la nodulación y por consiguiente una escasa reposición del nitrógeno removido del suelo. Aún cuando la inoculación está relativamente difundida, en la actualidad no se ha determinado la proporción relativa de nitrógeno fijado por las cepas introducidas respecto de las nativas o naturalizadas, ni la competencia que se genera en el suelo por la ocupación de los sitios potenciales para la formación de nódulos. Nuestra hipótesis de trabajo es: "la inoculación con cepas de Sinorhizobium meliloti debidamente caracterizadas y eficientes en la fijación del nitrógeno atmosférico mejorará el rendimiento de alfalfa en la región centro-sur de Córdoba". Los objetivos de este estudio son caracterizar fenotípica y genotípica el aislamiento Sinorhizobium meliloti 3DOh13 y evaluar su eficiencia simbiótica en el cultivo de alfalfa, mediante ensayos de infectividad, eficiencia y competencia con cepas nativas. La evaluación de la infectividad de la cepa comprende estudios de cinética de la nodulación, número total de nódulos y ubicación de los mismos en experiencias donde las plantas crecen en condiciones de invernáculo sobre un soporte de tierra:arena:perlita (2:1:1). Se realizarán ensayos de competitividad, coinoculando semillas con la cepa DOh13 y otras nativas, en bolsas plásticas con medio mineral en los que se desafiarán los distintos aislamientos. Se inoculan las plantas con sólo dos aislamientos y los nódulos de la raíz principal serán extraídos a fin de aislar los microorganismos ocupantes, los que serán diferenciados por marca de resistencia a antibioticos. La eficiencia en la fijación de nitrógeno será cuantificada por las técnicas de reducción del acetileno en el nódulo y, en caso de ser necesario, se usará el método de Kjeldahl (N total) para la raíz, tejido aéreo o planta entera. La caracterización genotípica de S. meliloti 3DOh13 incluirá métodos de fingerprint de ADN por técnicas de PCR y secuenciamiento del ADNr 16S. Esta investigación permitirá obtener información precisa sobre la respuesta de alfalfa a la inoculación con la cepa de referencia. El producto que se espera obtener es un nuevo inoculante, formulado con una cepa efectiva en la fijación de nitrógeno, debidamente caracterizada y con probada capacidad de adaptación a los suelos de la región

The use of forensic polycyclic aromatic hydrocarbon signatures and Compound Ratio Analysis Techniques (CORAT) for the source characterisation of petrogenic/pyrogenic environmental releases.

This study utilised recent developments in forensic aromatic hydrocarbon fingerprint analysis to characterise and identify specific biogenic, pyrogenic and petrogenic contamination. The fingerprinting and data interpretation techniques discussed include the recognition of: The distribution patterns of hydrocarbons (alkylated naphthalene, phenanthrene, dibenzothiophene, fluorene, chrysene and phenol isomers), • Analysis of “source-specific marker” compounds (individual saturated hydrocarbons, including n-alkanes (n-C5 through 0-C40) • Selected benzene, toluene, ethylbenzene and xylene isomers (BTEX), • The recalcitrant isoprenoids; pristane and phytane and • The determination of diagnostic ratios of specific petroleum / non-petroleum constituents, and the application of various statistical and numerical analysis tools. An unknown sample from the Irish Environmental Protection Agency (EPA) for origin characterisation was subjected to analysis by gas chromatography utilising both flame ionisation and mass spectral detection techniques in comparison to known reference materials. The percentage of the individual Polycyclic Aromatic Hydrocarbons (PAIIs) and biomarker concentrations in the unknown sample were normalised to the sum of the analytes and the results were compared with the corresponding results with a range of reference materials. In addition, to the determination of conventional diagnostic PAH and biomarker ratios, a number of “source-specific markers” isomeric PAHs within the same alkylation levels were determined, and their relative abundance ratios were computed in order to definitively identify and differentiate the various sources. Statistical logarithmic star plots were generated from both sets of data to give a pictorial representation of the comparison between the unknown sample and reference products. The study successfully characterised the unknown sample as being contaminated with a “coal tar” and clearly demonstrates the future role of compound ratio analysis (CORAT) in the identification of possible source contaminants.