Isolation,biodegradation ability and molecular detection of hydrocarbon degrading bacteria in petroleum samples from a Brazilian offshore basin

The detection of microorganisms with potential for biodeterioration and biodegradation in petroleum fields is of great relevance, since these organisms may be related to a decrease in petroleum quality in the reservoirs or damage in the production facilities. In this sense, petroleum formation water and oil samples were collected from the Campos Basin, Brazil, with the aim of isolating microorganisms and evaluating their ability to degrade distinct classes of hydrocarbon biomarkers (9,10-dihydrophenanthrene, phytane, nonadecanoic acid and 5α-cholestane). Twenty eight bacterial isolates were recovered and identified by sequencing their 16S rRNA genes. Biodegradation assays revealed that bacterial metabolism of hydrocarbons occurred through reactions based on oxidation, carbon–carbon bond cleavage and generation of new bonds or by the physical incorporation of hydrocarbons into microbial cell walls. Based on the biodegradation results, selective PCR-based systems were developed for direct detection in petroleum samples of bacterial groups of interest, namely Bacillus spp., Micrococcus spp., Achromobacter xylosoxidans, Dietzia spp. and Bacillus pumilus. Primer sets targeting 16S rRNA genes were designed and their specificity was confirmed in silico (i.e. computational analysis) and in PCR reactions using DNA from reference strains as positive and negative controls. Total DNA from oil was purified and the amplification tests revealed the presence of the target bacteria in the samples, unraveling a significant potential for petroleum deterioration in the reservoirs sampled, once proper conditions are present for hydrocarbon degradation. The application of molecular methods for rapid detection of specific microorganisms in environmental samples would be valuable as a supporting tool for the evaluation of oil quality in production reservoirs.     

A new analysis of the GJ581 extrasolar planetary system

We have done a new analysis of the available observations of the GJ581 exoplanetary system. Today this system is controversial due to choices that can be done in the orbital determination. The main ones are the occurrence of aliases and the additional bodies??the planets f and g??announced in Vogt et?al. (Astrophys J 723:954?C965, 2010). Any dynamical study of exoplanets requires the good knowledge of the orbital elements and the investigations involving the planet g are particularly interesting, since this body would lie in the habitable zone (HZ) of the star GJ581. This region, for this system, is very attractive of the dynamical point of view due to several resonances of two and three bodies present there. In this work, we investigate the conditions under which the planet g may exist. We stress the fact that the planet g is intimately related with the orbital elements of the planet d; more precisely, we conclude that it is not possible to disconnect its existence from the determination of the eccentricity of the planet d. Concerning the planet f, we have found one solution with period ??450?days, but we are judicious about any affirmation concerning this body because its signal is in the threshold of detection and the high period is in a spectral region where the occurrence of aliases is very common. Besides, we outline some dynamical features of the HZ with the dynamical map and point out the role played by some resonances laying there.     

Varre-Sai: The Recent Brazilian Fall

Varre-Sai, the most recent Brazilian meteorite fall, on June 19th, 2010 at Varre-Sai, in Rio de Janeiro State, Brazil (20°51??41??S; 41°44??.80??W). At least eight masses (total ~3.5?kg) were recovered. Most are totally covered by fusion crust. The exposed interior is of light-grey colour with a few dark shock veins. Five thin polished and etched sections were prepared from a slice weighing 35?g on deposit at the National Museum/UFRJ. It consists mostly of chondrules ranging in size from 0.35 to ~2.2?mm, and chondrule fragments enclosed in a crystalline matrix. The matrix consists of tiny isolated subhedral and anhedral crystals and opaque minerals that are intergrown with broken chondrules. The chondritic texture is poorly defined with chondrule textures that vary from non-porphyritic to porphyritic ones. The essential minerals are olivine (Fa_25±0.2) and low-Ca pyroxene (Fa_21.66±0.2Wo_1.4). Accessory minerals are plagioclase, apatite, Fe?CNi metal phases, troilite, chromite and magnetite. M?ssbauer spectroscopy analysis confirms that the mineral phases are olivine, pyroxene, troilite and kamacite/taenite. Chemical data indicate that Varre-Sai is a member of the low iron L chondrite group. The observed texture and mineral phases led us to classify Varre-Sai as an equilibrated petrologic type 5. The shock features of the minerals (undulatory extinction, planar structure and numerous cracks), as well as plagioclase partial or totally transformed to maskelynite, suggest a shock stage S4. Also, some post-impact metamorphic processes could be inferred from the meta-sulfide conjoint grains that show complex mixtures of kamacite?Ctaenite?Ctetrataenite and troilite. The occurrence of veins crosscutting the studied sections indicates that Varre-Sai was affected by a late fracturing event. Sealing of these fractures must have been a fast process, as shown by troilite globule textures pointing towards rapid solidification. The meteorite name was approved by the Nomenclature Committee of the Meteoritical Society (Meteoritic Bulletin, no 99).     

Correction to: Spatial distribution and estimation of rainfall trends and erosivity in the Epitácio Pessoa reservoir catchment,Paraíba,Brazil

Natural Hazards - The article “Spatial distribution and estimation of rainfall trends and erosivity in the Epitácio Pessoa reservoir catchment, Paraíba, Brazil”, written by da...     

Fractional Flow Speed-Up from Porous Windbreaks for Enhanced Wind-Turbine Power

The potential for porous windbreaks to enhance wind-turbine power production is studied using linearized theory and wind-tunnel experiments. Results suggest that windbreaks have the potential to substantially increase power production, while lowering mean shear, and leading to negligible changes in turbulence intensity. The fractional increase in turbine power output is found to vary roughly linearly with windbreak height, where a windbreak 10% the height of the turbine hub increases power by around 10%. Wind-tunnel experiments with a windbreak imposed beneath a turbulent boundary layer show the linearized predictions to be in good agreement with particle-image-velocimetry data. Power measurements from a model turbine further corroborate predictions in power increase. Moreover, the wake of the windbreak showed a significant interaction with the turbine wake, which may inform windbreak use in large wind farms. Power measurements from a second turbine downwind of the first with its own windbreak show that the net effect for multiple turbines is dependent on windbreak height.     

The impact of climate change on extreme precipitation in Sicily,Italy

Increasing precipitation extremes are one of the possible consequences of a warmer climate. These may exceed the capacity of urban drainage systems, and thus impact the urban environment. Because short‐duration precipitation events are primarily responsible for flooding in urban systems, it is important to assess the response of extreme precipitation at hourly (or sub‐hourly) scales to a warming climate. This study aims to evaluate the projected changes in extreme rainfall events across the region of Sicily (Italy) and, for two urban areas, to assess possible changes in Depth‐Duration‐Frequency (DDF) curves. We used Regional Climate Model outputs from Coordinated Regional Climate Downscaling Experiment for Europe area ensemble simulations at a ~12 km spatial resolution, for the current period and 2 future horizons under the Representative Concentration Pathways 8.5 scenario. Extreme events at the daily scale were first investigated by comparing the quantiles estimated from rain gauge observations and Regional Climate Model outputs. Second, we implemented a temporal downscaling approach to estimate rainfall for sub‐daily durations from the modelled daily precipitation, and, lastly, we analysed future projections at daily and sub‐daily scales. A frequency distribution was fitted to annual maxima time series for the sub‐daily durations to derive the DDF curves for 2 future time horizons and the 2 urban areas. The overall results showed a raising of the growth curves for the future horizons, indicating an increase in the intensity of extreme precipitation, especially for the shortest durations. The DDF curves highlight a general increase of extreme quantiles for the 2 urban areas, thus underlining the risk of failure of the existing urban drainage systems under more severe events.     

Experimental seismic shear force amplification in scaled RC cantilever shear walls with base irregularities

RC structural slender walls under large seismic excitation are expected to reach base moment capacity mainly affected by the first vibration mode. However, the base shear could be affected by higher modes once yielding in flexure has occurred, which might result in base shear underestimation in linear design. In this work, an experimental program is carried out on five RC rectangular walls 1:10 scaled. All five specimens considered irregularities at base, common in construction and one specimen did not consider shear reinforcement or boundary detailing. Tests are carried on a unidirectional shaking table and excitation is based on two Chile earthquake records with different intensities. Damage is concentrated at the wall base for all specimens; primary due to flexure with some participation of shear. For one of the records an average amplification of 1.3 is obtained, and a decrease in height of the resultant equivalent lateral force closes to 0.4 h_w. By increasing the intensity of the input record, amplification grows to an average of 1.7, while it decreases drastically when subjected to input records with low frequency content. No significant difference is observed in shear amplification in specimens with a base central opening, nor with setback, even though the cracking and failure mode was different for such specimens. Ductility demand shows no correlation when two different earthquakes are considered, whereas the frequency content and Arias intensity (I_a) of the input record directly affected the shear amplification.     

Brazilian spatial dynamics in the long term (1872–2000): “path dependency” or “reversal of fortune”?

This paper analyzes the spatial dynamics of Brazilian regional inequalities between 1872 and 2000 using contemporary tools. The first part of the paper provides new estimates of income per capita in 1872 by municipality using census and electoral information on income by occupation. The level of analysis is the Minimum Comparable Areas 1872–2000 developed by Reis et al. (áreas mínimas comparáveis para os períodos intercensitários de 1872 a 2000, 2007). These areas are the least aggregation of adjacent municipalities required to allow consistent geographic area comparisons between census years. In the second section of the paper, Exploratory Spatial Data Analysis, Markov chains and stochastic kernel techniques (spatially conditioned) are applied to the dataset. The results suggest that, in broad terms, the spatial pattern of income distribution in Brazil during that period of time has remained stable.