2,456 research outputs found
La signification des plis d'orientation méridienne dans l'Atlas tunisien centro-septentrional
L'analyse de divers secteurs de l'Atlas tunisien montre que les plis de direction N-S sont fréquents et qu'ils précèdent le plus souvent les cisaillements et les chevauchements vers le Sud-Est. Pendant le serrage miocène, la déformation, souple dans un premier temps, s'exerce sur un bâti affecté de fractures profondes, créant simultanément des plis de direction méridienne et atlasique. Elle évolue ensuite vers des cisaillements et des déplacements tangentiels vers le Sud-Est; ces déplacements sont guidés par les accidents NW-SE à E-W qui induisent dans la couverture mésozoïque des mouvements de translation avec transformatio
Some remarks on particle size effects on the abrasion of a range of Fe based alloys
The low-stress three body abrasion behaviour of a range of steels was investigated. The tests were carried out in a rubber wheel tester (according to ASTM G65-94, reapproved in 2000) at room temperature. The abrasive particles used were angular alumina particles of four different sizes. The results showed that, in general, the smaller particles (50 8m and 125 8m average size) caused more damage. With these particles, observations of surface morphology indicarted a more intense cutting and ploughing action, leading to more damage, whereas bigger particles i.e. larger 250 8m and 560 8m particles produced less damage, and their action involved more plastic deformation type wear. The 304 SS had a lower abrasion resistance than the 310 SS. For the austentic and ferritic steels the subsurface deformation was larger for impact with the coarser particles. Variations in substrate hardness had no effect on the abrasive behaviour observed. On the whole, the hardest steel (mild steel in martensitic condition) showed the higher extent of damage, irrespective of particle size
Morphological Characterization of Indoor Airborne Particles in Seven Primary Schools
This paper focuses on a study of fine (less than 2.5 µm) airborne particles collected inside seven primary schools located on a coastal Mediterranean area which has a significant industrial hub for the processing of clays and other minerals as raw materials. Of the seven schools, three are located in an urban area 20 km away from the main industrial hub, three are in a town located next to the industrial estate, and one is in a rural location, 30 km from the industrial area. The objective of this study is to identify the main types of particles found in the three examined environments. The particle matter identified in the fine particle samples is grouped into three main groups: mineral compounds, particles from combustion processes and phases emitted in high-temperature industrial processes. The mineral particles, which can come from natural or anthropogenic emissions, have been classified depending on their morphology as isometric allotriomorphs or subidiomorphs, with a tabular habit; acicular forms; or pure crystalline forms. Compounds from combustion processes have two types of morphologies: spheroid and dendritic soot particles. Additionally, in smaller quantities, spherical particles associated with high-temperature industrial processes, such as the emissions of ceramic tile-firing and frit-melting processes, are identified. A summary table is shown, which lists the characteristics, as well as the most significant origin of the main particles identified in the fine (<2.5 μm) airborne particles collected inside primary schools located in three different environments (urban, industrial and rural). A visual scale has been established based on the number of particles observed in the samples of the atmospheric particulate fraction between the sizes of 2.5 and 10 µm collected inside the schools. The ratios Ca/Si, S/Si, S/Ca and (Si+Ca)/S have been established. Results obtained may be useful in epidemiological studies in the ceramic cluster area in order to estimate children’s exposure to different indoor primary school microenvironments. Effective policies and mitigation measurements for the protection of children’s health should be carried out in this highly industrialized area
Carbon-based perovskite solar cells by screen printing with preheating
Carbon-based perovskite solar cells were manufactured by the screen-printing method using a triple mesoscopic layer of TiO, ZrO and carbon. The perovskite solution was infiltrated at the TiO/ZrO porous interface through the printed carbon layer on top of the ZrO. Using a simple preheating of the substrates and the perovskite solution, a film deposited in air can be obtained. Using this method, an air-processed CPSC made under a humid atmosphere with 55% RH achieved a PCE of 10.35%
Existence and Stability of Symmetric Periodic Simultaneous Binary Collision Orbits in the Planar Pairwise Symmetric Four-Body Problem
We extend our previous analytic existence of a symmetric periodic
simultaneous binary collision orbit in a regularized fully symmetric equal mass
four-body problem to the analytic existence of a symmetric periodic
simultaneous binary collision orbit in a regularized planar pairwise symmetric
equal mass four-body problem. We then use a continuation method to numerically
find symmetric periodic simultaneous binary collision orbits in a regularized
planar pairwise symmetric 1, m, 1, m four-body problem for between 0 and 1.
Numerical estimates of the the characteristic multipliers show that these
periodic orbits are linearly stability when , and are
linearly unstable when .Comment: 6 figure
Geometric Quantization of Topological Gauge Theories
We study the symplectic quantization of Abelian gauge theories in
space-time dimensions with the introduction of a topological Chern-Simons term.Comment: 13 pages, plain TEX, IF/UFRJ/9
Production of bamboo leaf ash by auto-combustion for pozzolanic and sustainable use in cementitious matrices
[EN] In the context of world concern with the environment, this study aims to characterize an auto combustion produced bamboo leaf ash (BLA) by its pozzolanic behaviour, reactivity and its influence in the total porosity, pore size distribution, tortuosity and mechanical behaviour of cementitious matrices. The chemical and physical characterization of the BLA was carried using X-ray fluorescence, determination of amorphous silica content, X-ray diffraction, Fourier Transform Infrared Spectrophotometry (FTIR), laser granulometry and field emission scanning electron microscopy (FESEM). The assessed BLA is a siliceous material (74.23%) with an amorphous nature due to the amorphous silica content, which represents 92.33% of the total silica. The BLA was classified as highly reactive by assessing its pH and conductivity in a saturated calcium hydroxide (CH) medium for different proportions and temperatures. Frattini analysis, the study of CH:BLA pastes (Thermogravimetric analysis and FTIR) and Portland cement (OPC)/pozzolan pastes (Thermogravimetric analysis and FESEM) are in agreement with this classification. The replacement of OPC by BLA improved the mechanical behaviour of the cementitious matrices, as well their durability. All the mortars containing BLA presented very similar compressive strength to a control mortar (100% OPC) after only 3 days of curing and at the following tested curing ages: 7, 28 and 90 days. In the mercury intrusion porosimetry analysis, the pastes with 20 and 30% BLA content presented higher tortuosity or fewer connected pores than the control paste. Thus, the auto-combustion method proved to be successful and BLA is a suitable alternative for sustainable high-performance matrices. (C) 2019 Elsevier Ltd. All rights reserved.The authors would like to thank SĂŁo Paulo Research Foundation (FAPESP), grant #2016/16403-5 and #2017/21563-4.Moraes, M.; Moraes, J.; Tashima, M.; Akasaki, J.; Soriano Martinez, L.; Borrachero Rosado, MV.; Paya Bernabeu, JJ. (2019). Production of bamboo leaf ash by auto-combustion for pozzolanic and sustainable use in cementitious matrices. Construction and Building Materials. 208:369-380. https://doi.org/10.1016/j.conbuildmat.2019.03.007S36938020
Parity implications for anthropometrical variables, lifestyle behaviors and dietary habits in pregnant women
Background. Maintaining an adequate health status
and appropriate lifestyles during pregnancy is of great
importance to prevent adverse outcomes for both
mother and baby. The present study aimed to assess
the nutritional status, socio-demographic features,
lifestyle behaviors and dietary habits of pregnant
women in Spain, and to identify the influence of parity
on these profiles.
Methods. This cross-sectional study included pregnant
women from regions all over Spain. The information was
collected through a 40 item questionnaire, previously
validated, by community health professionals.
Results. The 5,087 pregnant women analyzed had an
average age of 31.9 years with an adequate nutritional
status. The distribution of the sample was 56%
nulliparous and 44% multiparous. The nulliparous
reported a better self-perceived health status and
nutritional balance, and a lower incidence of gestational
diabetes mellitus. However, the multiparous showed
healthier lifestyle habits (lower rates of smoking and
alcohol consumption) and more physically active
patterns. Regarding diet, nulliparous pregnant women
consumed more dairy products, fresh fruit and nuts,
and less bread, rice/pasta/potatoes, meat, sausage and
buns/pastries than multiparous pregnant women.
Conclusions. Differences between analyzed patterns
were observed in anthropometrical variables, lifestyle
behaviors and dietary habits, which may require different nutritional messages to nulliparous as compared to
multiparous from a public health point of view.Fundamento. Durante el embarazo, el mantenimiento
de un adecuado estado de salud y estilos de vida, es
de gran importancia para prevenir resultados adversos
tanto para la madre como para el bebé. El presente estudio tuvo como objetivos evaluar el estado nutricional,
caracterĂsticas sociodemográficas, estilos de vida y hábitos alimentarios de mujeres embarazadas en España, e
identificar la influencia de la paridad sobre estos perfiles.
Material y método. Este estudio transversal incluyó
mujeres embarazadas de todas las comunidades autónomas de España. La información se recogió a través de
un cuestionario de 40 preguntas, previamente validado,
por profesionales de la salud comunitarios.
Resultados. Las 5.087 mujeres embarazadas presentaron una edad media de 31,9 años y un adecuado estado
nutricional. De la muestra un 56% fueron nulĂparas y un
44% multĂparas. Las mujeres nulĂparas declararon mejor autopercepciĂłn de su estado de salud y estado nutricional, y menor incidencia de diabetes mellitus gestacional. Sin embargo, las mujeres multĂparas mostraron
estilos de vida más saludables (tasas de consumo de
tabaco y alcohol más bajas) y un patrón de actividad
fĂsica más activo. En cuanto a la dieta, las nulĂparas
consumieron más lácteos, fruta fresca y frutos secos,
y menos pan, arroz/pasta/patatas, carne, embutidos y
bollos/pasteles que las multĂparas.
Conclusiones. Se observaron diferencias entre los grupos
analizados en cuanto a variables antropométricas, estilos de vida y hábitos alimentarios, que pueden requerir
distintos mensajes nutricionales para mujeres nulĂparas
y multĂparas, desde un punto de vista de Salud PĂşblica
Metaproteomics and metabolomics analyses of chronically petroleum-polluted sites reveal the importance of general anaerobic processes uncoupled with degradation
Crude oil is one of the most important natural assets for humankind, yet it is a major environmental pollutant, notably in marine environments. One of the largest crude oil polluted areas in the word is the semi-enclosed Mediterranean Sea, in which the metabolic potential of indigenous microbial populations towards the large-scale chronic pollution is yet to be defined, particularly in anaerobic and micro-aerophilic sites. Here, we provide an insight into the microbial metabolism in sediments from three chronically polluted marine sites along the coastline of Italy: the Priolo oil terminal/refinery site (near Siracuse, Sicily), harbour of Messina (Sicily) and shipwreck of MT Haven (near Genoa). Using shotgun metaproteomics and community metabolomics approaches, the presence of 651 microbial proteins and 4776 metabolite mass features have been detected in these three environments, revealing a high metabolic heterogeneity between the investigated sites. The proteomes displayed the prevalence of anaerobic metabolisms that were not directly related with petroleum biodegradation, indicating that in the absence of oxygen, biodegradation is significantly suppressed. This suppression was also suggested by examining the metabolome patterns. The proteome analysis further highlighted the metabolic coupling between methylotrophs and sulphate reducers in oxygen-depleted petroleum-polluted sediments
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