Anisotropy in large eddy simulations determined from SO(3) symmetry group

The issue of small-scale anisotropy in the context of eddy-viscosity-type subgrid-scale models is discussed in the present work. Recent developments in turbulence research suggest that anisotropy from large spatial scales is felt far into the inertial subrange of turbulence. This is of particular importance for subgrid-scale models of large eddy simulations. To address this issue, we present solutions of the random-phase Kolmogorov flow at moderate Reynolds numbers using direct numerical simulations and large eddy simulations with four subgrid-scale models: the Smagorinsky, the dynamic, the dynamic Clark, and the tensor-diffusivity models. The degree of anisotropy at different scales is analysed by decomposing the structure function into their irreducible representation of the SO(3) symmetry group. The results suggest that the dynamic model and the dynamic Clark model reproduce the statistical behaviour reasonably well, even in the anisotropic sectors at small length scales

Control of Thickness of PEDOT Electrodeposits on Glass/ITO Electrodes from Organic Solutions and its Use as Anode in Organic Solar Cells

AbstractPoly-ethylendioxythiophene (PEDOT) was electropolymerized from the monomer EDOT in acetonitrile (ACN) containing Bu4N+ClO4-, BF4- or PF6- ions as supporting electrolyte. The electrode used was transparent electrodes (Glass/ITO) in order to generate the anode of an organic solar cell (OSC). Potentiodynamic and potentiostatic electropolymerization techniques were used to make the conducting polymer deposits (E-PEDOT), which were obtained as a thin film onto the ITO surface. It was possible to control the thickness of the electrodeposited films in the range of 15 to 200nm measured by AFM. With the thinner films (until 100nm), it was observed that its absorbance at 700nm was linearly dependent with their thickness and it was possible to obtain an equation that was used to measure the films thickness of future experiments. The E-PEDOT films were successfully used for constructing OSC's and the efficiency values found were equivalent or slightly superior to those found with the classical PEDOT:PSS anode

A precise late Permian 40Ar/ 39Ar age for Central Iberian camptonitic lamprophyres

The Avila batholith of central Spain is composed, predominantly, of crustal-melt peraluminous granites cut by small-scale mafic alkaline bodies. Dating of the Gredos sector mafic camptonitic lamprophyre dykes was undertaken to constrain the Late Variscan tectonomagmatic evolution of the region. A well constrained late Permian, Capitanian, age of 264.5 ± 1.3 Ma was obtained by 40Ar/39Ar geochronology using amphibole separates. This new age clearly distinguishes the dykes from other episodes of alkaline mafic magmatism in the region. We suggest that the lamprophyre dykes were emplaced into already solidified granitoids after the tectonic control on magma generation changed from purely extensional to transtensional

New biostratigraphic data from the Callovian-Oxfordian La Manga Formation, Neuquén Basin, Argentina: Evidence from an ammonite condensed level

The La Manga Formation constitutes most of the sedimentary record of the Callovian-Oxfordian in the Neuquén Basin. This stratigraphic unit represents the middle part of the Lotena Mesosequence, which is dominated by carbonates with interbedded shales, marls, and occasional sandstones. Based on detailed stratigraphic work in the stratotype section (La Manga Creek, Mendoza), the depositional environments and the sea-level history of the La Manga Formation have been interpreted. Petrographic and field observations led to identification of nine facies distributed in two informal units. Unit 1 was deposited on a outer ramp setting, while deposition of unit 2 took place in the intertidal-supratidal environments. A condensed level close to the base of unit 1 has yielded Rehmannia sp., Rehmannia cf. paucicostata (Tornq.) and Homoeoplanulites sp., from the Lower Callovian Bodenbenderi-Proximum Zones, and Peltoceratoides sp. and Rursiceras sp. from the Upper Callovian and also in the Lower Oxfordian Peltoceratoides-Parawedekindia Zone. The condensed level is overlain by a Middle Oxfordian succession characterized by Perisphinctes (?Arisphinctes) sp., Perisphinctes (?Kranaosphinctes) sp., Mirosphinctes sp., Perisphinctes (?Antilloceras) cf. prophetae Gygi & Hill., Perisphinctes (?Otosphinctes) sp., Perisphinctes (?Subdiscosphinctes) sp., and Perisphinctes (?Kranaosphinctes) cf. decurrens (Buck.) of the Perisphinctes-Araucanites Zone, which was correlated with the upper part of the Cordatum Standard Zone to the Transversarium Standard Zone, and probably to the lower part of the Bifurcatus Standard Zone. Unit 2 has yielded small Mirosphinctes sp., indicating an Oxfordian age. The sharp contact between the outer ramp facies of unit 1 and the overlying intertidal-supratidal facies of unit 2 can be interpreted as the result of an abrupt fall (forced regression) of the relative sea level during the end of Middle Oxfordian or Upper Oxfordian. These results could be used for comparison with other localities in the Neuquén Basin providing additional data for Lower Callovian-Middle Oxfordian deposits

Processo hierárquico analítico na gestão da conservação de vias urbanas pavimentadas

O objetivo geral deste trabalho é apresentar o estudo de critérios de decisão para um modelo de gestão da conservação de vias urbanas pavimentadas com a aplicação do Processo Hierárquico Analítico (AHP - Analytic Hierarchy Process). O AHP éé utilizado com o objetivo de definir o grau de importância (pesos) dos critérios relevantes ao processo decisório. Com base no Método de Comparação Par a Par, a fase de definição da importância relativa de cada critério contou com um painel de especialistas que preencheram planilhas eletrônicas e atribuíram pesos aos critérios de decisão. No intuito de ampliar as expectativas em relação aos critérios utilizados, a metodologia aplicada trouxe bons resultados, por considerar um grande número de critérios relevantes no que diz respeito ao estudo de prioridades em vias urbanas. O processo AHP permitiu calcular a consistência dos julgamentos efetuados, o que garante um elevado nível de confiabilidade no conjunto de pesos resultantes

Palaeoenvironmental significance of middle Oxfordian deep marine deposits from La Manga Formation, Neuquén Basin, Argentina

[EN] The Callovian-Oxfordian of the Neuquén Basin (Argentina) is characterized by an extensive marine carbonate system (La Manga Formation) with a predominance of shallow and middle ramp deposits, although locally in tectonically controlled settings, deeper deposits also formed. These middle Oxfordian deeper deposits consist of mudstone-wackestone carbonates alternating with black shales and show marked centimetre-scale rhythmicity, probably controlled by the Earth’s orbit parameters, mainly precession and eccentricity. The present study was designed to examine these deposits in terms of their sedimentology, geochemistry, and small-scale stratigraphy in Arroyo Los Blancos, southern Mendoza Province, where they are exceptionally well exposed and preserved. Results indicate that the sediments were deposited in an anoxic to dysoxic, relatively deep, sea-floor environment as revealed by the presence of: a) organic-rich shales, b) undisrupted lamination in most facies, c) pyrite framboids, and d) absence or scarcity of trace fossils and benthic fauna. Thin beds of graded wackestone-packstone and accumulations of thin shells of Bositra bivalves indicate sporadic reworking of the sea floor by weak currents. Organic petrology, Rock-Eval pyrolysis and thermal maturity indicators were used to characterize TOC and different types of organic matter. Low pyrolysis S yields along with low hydrogen indices suggest poor kerogen convertibility. Vitrinite reflectance (%Ro) ranged from 2.39 to 2.97 with an average of 2.70. The thermal alteration index (TAI) was 4+(5), indicating overmaturity. A tectono-sedimentary model is proposed for these deposits. According to this model, the relatively deep, organic-matter rich facies of La Manga Formation would have been deposited in the deepest zones of topographic lows controlled by tilting and differential subsidence of tectonic blocks bounded by normal faults.These faults were probably inherited from previous extensional tectonics of Late Triassic - Early Jurassic age.[ES] El Calloviense-Oxfordiense en el norte de la Cuenca Neuquina (Argentina) estuvo caracterizado por el desarrollo de un amplio sistema de rampa carbonatada (Formación La Manga) en el que predominaron los depósitos de rampa media y somera aunque localmente, y debido a control tectónico, pudieron acumularse depósitos más profundos. Estos depósitos, de edad Oxfordiense medio, están expuestos y preservados excepcionalmente en la zona de Arroyo Los Blancos, al sur de la provincia de Mendoza, y su estudio sedimentológico, geoquímico y estratigráfico representan el objetivo de este trabajo. Consisten en carbonatos (mudstone-wackestone) con acumulaciones de finas conchas de bivalvos de tipo Bositra que indican retrabajamientos esporádicos del sustrato marino debido a corrientes de baja intensidad. Se han caracterizado diferentes tipos de materia orgánica y TOC mediante petrología orgánica, Rock-Eval Pyrolisis e indicadores de madurez térmica. Los bajos valores en el campo del S unido al también bajo índice de H sugieren una baja convertibilidad de Kerógeno. La reflectancia de la vitrinita (%Ro) tiene un rango que oscila entre 2,39 y 2,97, con una media de 2,70, mientras que el índice de alteración térmico (TAI) es de 4+(5) indicando sobremaduración. Se propone también un modelo tectono-sedimentario para estos depósitos. En este modelo, estas facies relativamente profundas y ricas en materia orgánica de la Formación La Manga estarían depositadas en la parte más deprimida de bajos topográficos controlados por una subsidencia diferencial y de pulsos en bloques marcados por fallas normales heredadas probablemente de una tectónica extensional durante el Triásico Superior-Jurásico Inferior.Peer reviewe

Application of an HS–MS for the detection of ignitable liquids from fire debris

In arsonattacks,accelerantssuchasignitableliquidsarecommonlyusedtoinitiateoracceleratea fire. The detection of ignitable liquid residues at fire scenes is therefore a key step in fire investigations.The most widely used analytical technique for the analysis of accelerants is GC–MS. However,pre-concentration of the ignitable liquid residues is required prior to the chromatographic analysis.Thestandard method, ASTM E1412, involves passive headspace concentration with activated charcoal strips as a method to isolate the ignitable liquid residues from fire debris and these residues are subsequently desorbed from the carbon strip with solvents such as carbon disulfide. In the work described here, an alternative analytical technique based on an HS–MS (headspace mass spectrometry) has been developed for the thermal desorption of the carbon strips and analysis of different ignitable liquid residues in fire debris.The working conditions for the HS–MS analytical procedure were optimized using different types of fire debris (pine wood burned with gasoline and diesel). The optimized variables were desorption temperature and desorption time.The optimal conditions were 145 °C and 15 min. The optimized method was applied to a set of fire debris samples. In order to simulate post burn samples several accelerants (gasoline, diesel, citronella, kerosene, paraffin, and alcohol) were used to ignite different substrates (wood, cotton, cork, paper, and paperboard). chemometric methods (cluster analysis and discriminant analysis) were applied to the total ion spectrum obtained from the MS (45–200m/z) to discriminate between the burned samples according to the accelerant used. The method was validated by analyzing all samples by GC–MS according to the standard methods ASTM E1412 and ASTM E1618. The results obtained on using the method developed in this study were comparable to those obtained with the reference method. However, the newly developed HS–MS method is faster, safer, and more environmental friendly than the standard method

Gasoline analysis by headspace mass spectrometry and near infrared spectroscopy

Headspace mass spectrometry and near infrared spectroscopy in combination with chemometric tools, including hierarchical cluster analysis and linear discriminant analysis, have been used for the classification of gasoline according to the research octane number. Volatile components were studied by headspace mass spectrometry whereas the whole gasoline samples were studied by near infrared spectroscopy. Sample pretreatment was not required for either analysis. A set of 60 samples belonging to two different research octane numbers (95# and 98#) was analyzed by both techniques. The best results were obtained on using linear discriminant analysis, which allowed a full discrimination of the gasoline samples using only four m/z ratios (46, 59, 95 and 98) in the case of headspace mass spectrometry and three regions (below 1000 nm, 1400–1500 nm and 1600 nm) in the case of near infrared spectroscopy

New Headspace-Mass Spectrometry Method for the Discrimination of Commercial Gasoline Samples with Different Research Octane Numbers

A method for the discrimination of different gasoline samples according to their RON has been developed using an HS-MS system. The working conditions for the HS-MS analytical procedure were optimized by experimental design. The variables optimized were incubation temperature, incubation time, and sample volume. The optimal conditions were as follows: 145 °C incubation temperature, 10 min incubation time, and 80 μL sample volume. The optimized method was applied to a set of 30 gasoline samples with different RON values (95# and 98#). An hierarchical cluster analysis was applied in which the m/z (45−200 m/z) values were used as a variable to form groups. A perfect classification (100%) of the gasoline samples according to their RON was achieved. A linear discriminant analysis was carried out and the resulting linear discriminant function enabled a perfect classification of the gasoline samples according to the RON using only the m/z values of 88, 95, and 112. These results demonstrate the capacity of the new technique for the discrimination of gasoline samples according to their RON and the applicability of this method in this field. For the first time, HS-MS was used for this purpose. The main advantage of HS-MS vs previous methodologies is that no chromatographic separation and no sample manipulation are required. HS-MS is therefore faster than the current techniques used in these kinds of studies; it is also cheaper, ecofriendly, and easy to use for routine analysis

Urban life promotes delayed dispersal and family living in a non‑social bird species

In some vertebrate species, family units are typically formed when sexually mature individuals delay dispersal and independent breeding to remain as subordinates in a breeding group. This behaviour has been intensively studied in gregarious species but has also been described in non-social species where ecological and evolutionary drivers are less known. Here, we explore factors that favour delayed dispersal and family living and potential benefts associated with this strategy in a non-social, monogamous species (the burrowing owl, Athene cunicularia) occupying urban and rural habitats. Our results show that family units arise when frst-year individuals, mainly males, delay their dispersal to stay in their natal nests with their parents. This delayed dispersal, while still uncommon, was more prevalent in urban (7%) than in rural (3%) habitats, and in areas with high conspecifc density and productivity. Birds delaying dispersal contributed to the genetic pool of the ofspring in 25% of the families analysed, but did not increase the productivity of the nests where they remained. However, their presence was related to an improvement in the body condition of chicks, which was ultimately linked to a slightly positive efect in ofspring future survival probabilities. Finally, delayed dispersers were recruited as breeders in high-quality urban territories and closer to their natal nests than individuals dispersing during their frst year of life. Thus, our results suggest that delaying dispersal may be mainly related to opportunities to inheriting a good quality territory, especially for males. Our study contributes to understanding the role played by habitat quality in promoting delayed dispersal and family living, not only in social but also non-social species, highlighting its impact in the ecology and evolution of animal populationsPeer reviewe