946 resultados para Physico-mineral-chemical correlation to ancient texts
Resumo:
In this study we present an initial dataset of Mn/Ca and Fe/Ca ratios in tests of benthic foraminifera from the Peruvian oxygen minimum zone (OMZ) determined with SIMS. These results are a contribution to a better understanding of the proxy potential of these elemental ratios for ambient redox conditions. Foraminiferal tests are often contaminated by diagenetic coatings, like Mn rich carbonate- or Fe and Mn rich (oxyhydr)oxide coatings. Thus, it is substantial to assure that the cleaning protocols are efficient or that spots chosen for microanalyses are free of contaminants. Prior to the determination of the element/Ca ratios, the distributions of several elements (Ca, Mn, Fe, Mg, Ba, Al, Si, P and S) in tests of the shallow infaunal species Uvigerina peregrina and Bolivina spissa were mapped with an electron microprobe (EMP). To visualize the effects of cleaning protocols uncleaned and cleaned specimens were compared. The cleaning protocol included an oxidative cleaning step. An Fe rich phase was found on the inner test surface of uncleaned U. peregrina specimens. This phase was also enriched in Al, Si, P and S. A similar Fe rich phase was found at the inner test surface of B. spissa. Specimens of both species treated with oxidative cleaning show the absence of this phase. Neither in B. spissa nor in U. peregrina were any hints found for diagenetic (oxyhydr)oxide or carbonate coatings. Mn/Ca and Fe/Ca ratios of single specimens of B. spissa from different locations have been determined by secondary ion mass spectrometry (SIMS). Bulk analyses using solution ICP-MS of several samples were compared to the SIMS data. The difference between SIMS analyses and ICP-MS bulk analyses from the same sampling sites was 14.0-134.8 µmol mol-1 for the Fe/Ca and 1.68(±0.41) µmol mol-1 for the Mn/Ca ratios. This is in the same order of magnitude as the variability inside single specimens determined with SIMS at these sampling sites (1sigma[Mn/Ca] = 0.35-2.07 µmol mol-1; 1sigma[Fe/Ca] = 93.9-188.4 µmol mol-1). The Mn/Ca ratios in the calcite were generally relatively low (2.21-9.93 µmol mol-1) but in the same magnitude and proportional to the surrounding pore waters (1.37-6.67 µmol mol-1). However, the Fe/Ca ratios in B. spissa show a negative correlation to the concentrations in the surrounding pore waters. Lowest foraminiferal Fe/Ca ratios (87.0-101.0 µmol mol-1) were found at 465 m water depth, a location with a strong sharp Fe peak in the pore water next to the sediment surface and respectively, high Fe concentrations in the surrounding pore waters. Previous studies found no living specimens of B. spissa at this location. All these facts hint that the analysed specimens already were dead before the Fe flux started and the sampling site just recently turned anoxic due to fluctuations of the lower boundary of the OMZ near the sampling site (465 m water depth). Summarized Mn/Ca and Fe/Ca ratios are potential proxies for redox conditions, if cleaning protocols are carefully applied. The data presented here may be rated as base for the still pending detailed calibration.
Resumo:
In the recent discussion how biotic systems may react to ocean acidification caused by the rapid rise in carbon dioxide partial pressure (pCO2) in the marine realm, substantial research is devoted to calcifiers such as stony corals. The antagonistic process-biologically induced carbonate dissolution via bioerosion- has largely been neglected. Unlike skeletal growth, we expect bioerosion by chemical means to be facilitated in a high-CO2 world. This study focuses on one of the most detrimental bioeroders, the sponge Cliona orientalis, which attacks and kills live corals on Australia's Great Barrier Reef. Experimental exposure to lowered and elevated levels of pCO2 confirms a significant enforcement of the sponges' bioerosion capacity with increasing pCO2 under more acidic conditions. Considering the substantial contribution of sponges to carbonate bioerosion, this finding implies that tropical reef ecosystems are facing the combined effects of weakened coral calcification and accelerated bioerosion, resulting in critical pressure on the dynamic balance between biogenic carbonate build-up and degradation.
(Table 3) Major, trace, and rare earth element analyses of whole-rock samples from ODP Hole 148-896A
Resumo:
The rules governing the trade of goods in global markets have shifted toward non-tariff measures related to environmental and chemical safety. Unlike traditional environmental/safety requirements, the scope of modern regulations covers products’ environmental performance and chemical safety. To comply with these modern regulations, production practices along the entire supply chain must be realigned to manage certain chemical substances incorporated into the final product. This paper examines the implications of product-related environmental and chemical safety regulations on different firms operating in Thailand.
Resumo:
En la práctica habitual, para la elaboración de morteros se recomienda la utilización de granulometrías continuas. El requisito de continuidad y que los tamaños de partícula se encuentren dentro de los límites establecidos por “husos granulométricos” surge de las teorías clásicas de Fuller – Thompson y se apoya en la necesidad de obtener mezclas con adecuada docilidad en el estado fresco. Sin embargo, las distribuciones continuas de árido no representan las únicas alternativas para obtener mezclas que tengan una adecuada docilidad en estado fresco y mediante nuevos criterios de interferencia de partículas es posible demostrar que las distribuciones discontinuas aun siendo más compactas y con menor requerimientos de volumen de pasta pueden ser igual de dóciles en estado fresco. Aunque el volumen mínimo de pasta está condicionado por su fluidez y viscosidad estos parámetros pueden modificarse mediante la incorporación de filler de distinta naturaleza y aditivos químicos de reciente desarrollo. En consecuencia, se propone analizar la posibilidad de minimizar el contenido de pasta de morteros de base cemento, manteniendo las prestaciones en el estado fresco, con el objetivo de obtener una mejor estabilidad volumétrica, posibilitando mejor control de la retracción y de la fisuración. Para ello se emplearán criterios de interferencia de partículas, combinados con el uso de filler de distinta naturaleza La reducción del contenido de pasta conducirá también a mejorar el perfil sostenible de los morteros. El proceso de optimización tiene una base racional y, por lo tanto, será aplicable a distintos tipos de mortero, y las proporciones óptimas podrán adecuarse según las prestaciones requeridas para el material. SUMMARY In common practice, continuous sand gradings are recommended to produce ordinary mortars. This requirement, along with grading limits are based on classical theories, such as Fuller, aimed at achieving a reasonable packing density without compromising workability at the fresh state. Nevertheless, there are other alternatives, such as discontinuous curves based on particle interference criteria, which are capable of having even higher packing density. The less the content of voids in the granular skeleton, the less the amount of cement paste required to fill in these voids and coating the particles. Yet, the minimum volume of paste in a mortar is determined by requirements associated to the fresh state and thus, fluidity and viscosity of the paste play a significant role on the matter. These two properties can be modified by the use of suitable fillers and by the use of last-generation chemical admixtures. As a result, it is proposed to analyse the possibility of combining current particle interference criteria with the use of different types of filler and chemical admixtures to optimise cement-based mortar formulations. This optimisation is aimed at reducing the paste content while maintaining a suitable performance at the fresh state. The reduction in paste content would lead to a better dimensional stability, with better control of shrinkage and cracking behaviour. The foreseen optimisation process will have a strong rational basis and thus, it should be potentially useful to optimise mortar proportions according to a performance-based approach.
Resumo:
In this work, we present a novel method to compensate the movement in images acquired during free breathing using first-pass gadolinium enhanced, myocardial perfusion magnetic resonance imaging (MRI). First, we use independent component analysis (ICA) to identify the optimal number of independent components (ICs) that separate the breathing motion from the intensity change induced by the contrast agent. Then, synthetic images are created by recombining the ICs, but other then in previously published work (Milles et al. 2008), we omit the component related to motion, and therefore, the resulting reference image series is free of motion. Motion compensation is then achieved by using a multi-pass non-rigid image registration scheme. We tested our method on 15 distinct image series (5 patients) consisting of 58 images each and we validated our method by comparing manually tracked intensity profiles of the myocardial sections to automatically generated ones before and after registration. The average correlation to the manually obtained curves before registration 0:89 0:11 was increased to 0:98 0:02
Resumo:
En el presente estudio de tesis doctoral analizamos un texto literario francés del siglo XVI en el que aparecen 217 juegos. Como valor añadido se trata de parte de un texto reconocido mundialmente por la Literatura Universal como es el Gargantua de François Rabelais. A tenor de la conocida y famosa definición de Gimnasia establecida por Francisco de Amorós y Ondeano allá por 1830 en su Manuel d'éducation physique, gymnastique et morale, uno de los objetos de estudio en nuestra ciencia es la relación de nuestros movimientos con nuestras costumbres. Para ello indudablemente debemos recurrir a todo tipo de fuentes, escritas, orales o de otro tipo, para analizarlas. “La gimnasia es la ciencia razonada de nuestros movimientos, de sus relaciones con nuestros sentidos, nuestra inteligencia, nuestros sentimientos, nuestras costumbres y el desarrollo de todas nuestras facultades...” Costumbres, tradición e historia, en definitiva, que se contrasta con los medios utilizados en su análisis, herramientas TIC como son librerías digitales, buscadores de textos y palabras. A través del análisis de textos de diversa índole hemos ido obteniendo datos sobre los juegos. Estas fuentes han sido novelas, diccionarios, enciclopedias y ensayos desde el siglo XIV hasta obras contemporáneas. Se ha realizado un análisis estadístico de estas fuentes lo que ha dado a este estudio otro valor añadido desde un punto de vista metodológico. El resultado del estudio se ha plasmado en una colección de fichas creadas a partir de un estudio comparativo de diferentes fichas de juegos de autores de relevancia. ABSTRACT Gymnastics is the reasoned science of our movements, of its relations with our senses, our intelligence, our feelings, our customs and the development of all our faculties… In accordance with the all known famous definition of Gymnastics that established Don Francisco de Amorós and Ondeano in 1830 in his Manuel d'éducation physique, gymnastique et morale, one of the objects of study in our science is the relation of our movements with our customs. For it doubtlessly we must resort to all type of sources, written, oral or of another type, to analyze them. In the present doctoral thesis study we analyzed a French literary text of the XVI th century in which they appear 217 games. As added value treats world-wide from a recognized text by Universal Literature as it is the Gargantua of François Rabelais. Customs, tradition and history, really, that are resisted with means used in its analysis, TIC tools as they are digital libraries and tools to seek texts and words. Through text analysis of diverse nature we have been collecting data on the games. These sources have been novels, dictionaries, encyclopedias and tests from century XIV to contemporary works. A statistical analysis of these sources has been made which has given to this study another value added from a methodological point of view. The result of the study has been resumed in index cards created from a comparative cards study from different relevant authors.