998 resultados para sustainable chemistry


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The purpose of this study was to determine whether there were significant differences in accounting indicators when comparing sustainable enterprises to other similar companies that are not considered as sustainable. The Corporate Sustainability Index of BM (São Paulo Stock, Commodities and Futures Exchange) was the criterion selected to break down the samples into sustainable and non-sustainable enterprises. The accounting indicators were separated into two kinds: risk (dividend payout, percentage growth of assets, financial leverage, current liquidity, asset size, variability of earnings, and accounting beta) and return (ROA, ROE, asset turnover, and net margin). We individually analyzed the companies in the energy sector, followed by those in the banking sector, as well as the entire ISE portfolio as of 2008/2009, including all the sectors. Mann-Whitney tests were performed in order to verify the difference of the means between the groups (ISE and non-ISE). The results, considering the method chosen and the time span covered by the study, indicate that there are no differences between sustainable companies and the others, when they are assessed by the accounting indicators used here.

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A comparative systematic study of the CrO2F2 compound has been performed using different conventional ab initio methodologies and density functional procedures. Two points have been analyzed: first, the accuracy of results yielded by each method under study, and second, the computational cost required to reach such results. Weighing up both aspects, density functional theory has been found to be more appropriate than the Hartree-Fock (HF) and the analyzed post-HF methods. Hence, the structural characterization and spectroscopic elucidation of the full CrO2X2 series (X=F,Cl,Br,I) has been done at this level of theory. Emphasis has been given to the unknown CrO2I2 species, and specially to the UV/visible spectra of all four compounds. Furthermore, a topological analysis in terms of charge density distributions has revealed why the valence shell electron pair repulsion model fails in predicting the molecular shape of such CrO2X2 complexes

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Résumé Scientific:Pétrologie et Géochimie du Complexe Plutonique de Chaltén et les conséquences pour l'évolution magmatique et tectonique du Andes du Sud (Patagonia) pendant le MiocèneLe sujet de cette thèse est le Complexe Plutonique de Chaltén (CHPC), situé à la frontière entre le Chili et l'Argentine, en Patagonie (49°15'S). Ce complexe s'est mis en place au début du Miocène, dans un contexte de changements tectoniques importants. La géométrie et la vitesse de migration des plaques en Patagonie a été modifiée suite l'ouverture de la plaque Farallon il y a 25Ma (Pardo-Casas and Molnar 1987) et la subduction de la ride active du Chili sous la plaque sud-américaine il y a 14Ma (Cande and Leslie 1986). Les effets de cette reconfiguration tectonique sur la morphologie et le magmatisme de la plaque supérieure sont encore sujets à discussion. Dans ce contexte, un groupe d'intrusions miocènes - telle que le CHPC - est particulièrement intriguant, car en position transitionnelle entre le batholithe patagonien et l'arc volcanique cénozoïque et récent à l'ouest, et les laves de plateau de Patagonie à l'est (Fig. 1). A cause de leur position tectonique transitoire, ces plutons isolés hors du batholithe représentent un endroit clé pour comprendre les interactions entre la tectonique à large échelle et le magmatisme en Patagonie. Ici, je présente de nouvelles données de terrain, petrologiques, géochimiques et géochronologiques dans le but de caractériser la nature du CHPC, qui était largement inconnu avant cette étude, dans le but de tester l'hypothèse de migration de l'arc et erosion par subduction.Les résultats de l'investigation géochimique (chapitre 2) montrent que le CHPC n'est qu'un exemple parmi les plutons isolés d'arrière arc ave une composition calco-alcaline caractéristique, c-à-d une signature d'arc. La plupart de ces plutons isolés ont une composition alcaline. Le CHPC, contrairement, a une signature calco-alcaline avec Κ intermédiaire, tel que le batholithe patagonien et la plupart des roches volcaniques quaternaires liées à l'arc le long des Andes.De nouvelles données géochronologiques U-Pb de haute précision sur des zircons, acquis par TIMS, sur le CHPC donnent des âges entre 17.0 et 16.4Ma. Les âges absolus sont en accord avec la séquence intrusive déduite des relations de terrain (chapitre 1). Ces données sont les premières contraintes d'âge U-Pb sur le CHPC. Elles montrent clairement que l'histoire magmatique du CHPC n'a pas de lien direct avec la subduction de la ride à cette latitude (Cande and Leslie 1986), car le complexe est au moins 6Ma plus ancien.Une comparaison en profondeur avec les autres intrusions d'âge Miocène en Patagonie révèlent - pour la première fois - une évolution temporelle intéressante. Il y a une tendance E-W distincte au magmatisme calco-alcalin entre 20-16Ma avec une diminution de l'âge vers l'est - le CHPC est l'expression la plus orientale de cette tendance. Je suggère que la relation espace-temps reflète une migration vers l'est (vers le continent) de l'arc magmatique. Je propose que le facteur principal contrôlant cette migration est la subduction rapide suite à la reconfiguration de la vitesse des plaques tectoniques après l'ouverture la plaque Farallon (à ~26Ma) qui résulterait en une déformation importante ainsi qu'à des taux élevés d'érosion dans la fosse de subduction.Les rapports d'isotopes radiogéniques (Pb, Sr, Nd) élevés, une signature 6018 basse et un rapport Th/La élevé sont des paramètres distinctifs pour les roches mafiques du CHPC. Le modèle isotopique présenté (chapitre 2) suggère que cette signature reflète une contamination de la source, dans le coin de manteau, plutôt qu'une contamination crustale. La signature des éléments en trace du CHPC indiquent que le coin de manteau a été contaminé par des composés terrigènes, le plus vraisemblablement par des sédiments paléozoïques.Les travaux de terrain, la pétrographie et la géothermobarométrie ont été utilisés dans le but de comprendre l'histoire interne du CHPC (chapitre 3). Ces données suggèrent deux niveaux distincts de cristallisation : l'un dans la croûte moyenne (6 à 4.5kbar) et l'autre à un niveau peu profond (3.5 à 2kbar). La modélisation isotopique AFC de la contamination crustale indique des taux variables d'assimilation, qui ne sont pas corrélés avec le degré de différenciation. Cela suggère que différents volumes de magma se sont différenciés en profondeur, de façon indépendante. Cela implique que le CHPC se serait formés en plusieurs puises de magmas provenant d'au moins trois sources différentes. Les textures des granodiorites et des granites indiquent des teneurs élevées en cristaux avant la mise en place et, par conséquent, des températures d'emplacement faibles. Les observations de terrain montrent que les roches mafiques sont déformées, alors que ce n'est pas le cas pour les granodiorites et granites (plus jeunes). La déformation des roches mafiques est encore sujet de recherche, afin de savoir si elle est liée à la déformation régionale en régime compressif ou à l'emplacement lui-même. Cependant, la mise en place de grand volume de magma felsique riche en cristaux suggère un régime d'extension.Scientific Abstract:Petrology and chemistry of the Chaltén Plutonic Complex and implications on the magmatic and tectonic evolution of the Southernmost Andes (Patagonia) during the MioceneThe subject of this thesis is the Chaltén Plutonic Complex (CHPC) located at the frontier between Chile and Argentina in Patagonia (at 49° 15 'Southern latitude). This complex intruded during early Miocene in a context of major tectonics changes. The plate geometry of Patagonia has been modified by changes in the plate motions after the break up of the Farallôn plate at 25Ma (Pardo-Casas and Molnar 1987) and by the subduction of the Chile spreading Ridge beneath South-America at 14 Ma (Cande and Leslie 1986). The effects of this tectonic setting on the morphology and the magmatism of the overriding plate are a matter of on-going discussion. Particularly intriguing in this context is a group of isolated Miocene intrusions - like the CHPC - which are located in a transitional position between the Patagonian Batholith and the Cenozoic and Recent volcanic arc in the West, and the Patagonian plateau lavas in the East (Fig. 1). Due to their transient tectonic position these isolated plutons outside the batholith represent a key to understanding the interaction between global-scale tectonics and magmatism in Patagonia. Here, I present new field, penological, geochemical and geochronological data to characterize the nature of the CHPC, which was largely unknown before this study, in order to test the hypothesis of time- transgressive magmatism.The results of the geochemical investigation (Chapter 2) show that the CHPC is only one among these isolated back-arc plutons with a characteristic calc-alkaline composition, i.e. arc signature. Most of these isolated intrusives have an alkaline character. The CHPC, in contrast, has a medium Κ calc-alkaline signature, like the Patagonian batholith and most of the Quaternary arc-related volcanic rocks along the Andes.New high precision TIMS U-Pb zircon dating of the CHPC yield ages between 17.0 to 16.4 Ma. The absolute ages support the sequence of intrusion relations established in the field (Chapter 1). These data are the first U-Pb age constraints on the CHPC, and clearly show that the magmatic history of CHPC has no direct link to the subduction of the ridge, since this complex is at least 6 Ma older than the time of collision of the Chile ridge at this latitude (Cande and Leslie 1986).An in-depth comparison with other intrusion of Miocene age in Patagonia reveals - for the first time - an interesting temporal pattern. There is a distinct E-W trend of calc-alkaline magmatism between 20-16 Ma with the younging of ages in the East - the CHPC is the easternmost expression of this trend. I suggest that this time-space relation reflects an eastward (landward) migration of the magmatic arc. I propose that main factor controlling this migration is the fast rates of subduction after the major reconfigurations of the plate tectonic motions after the break up of the Farallôn Plate (at -26 ) resulting in strong deformation and high rates of subduction erosion.High radiogenic isotope ratios (Pb, Sr, Nd) ratios, low 5018 signature and high Th/La ratios in mafic rocks are distinctive features of the CHPC. The presented isotopic models (Chapter 2) suggest that this signature reflects source contamination of the mantle wedge rather than crustal contamination. The trace element signature of the CHPC indicates that the mantle wedge was contaminated with a terrigenous component, most likely from Paleozoic sediments.Fieldwork, petrography and geothermobarometry were used to further unravel the internal history of the CHPC (Chapter 3). These data suggest two main levels of crystallization: one a mid crustal levels (6 to 4.5 kbar) and other a shallow level (3.5 to 2 kbar). Isotopic AFC modeling of crustal contamination indicate variable rates of assimilation, which are not correlated with the degree of differentiation. This suggests that different batches of magma differentiate independently at depths. This implies that the CHPC would have formed by several pulses of magmas from at least 3 different sources. Textures of granodiorites and granites indicate a high content of crystals previous to the emplacement and consequently low emplacement temperatures. Field observations show that the mafic rocks are deformed, whereas the (younger) granodiorites and granites are not. It is still subject of investigation whether the deformation of the mafic rocks is related to regional deformation during a compressional regime or to the emplacement it self. However, the emplacement of huge amount of crystal rich felsic magmas suggests an extensional regime.Résumé Grand PublicPétrologie et Géochimie du Complexe Plutonique de Chaltén et les conséquences pour l'évolution magmatique et tectonique du Andes du Sud (Patagonia) pendant le MiocèneLe Complexe Plutonique de Chaltén (CHPC) est un massif montagneux situé à 49°S à la frontière entre le Chili et l'Argentine, en Patagonie (région la plus au sud de l'Amérique du Sud). Il est composé de montagnes qui peuvent atteindre plus de 3000 mètres d'altitude, telles que le Cerro Fitz Roy (3400m) et le Cerro Torre (3100m). Ces montagnes sont composées de roches plutoniques, c.-à-d. des magmas qui se sont refroidis et ont cristallisés sous la surface terrestre.La composition chimique de ces roches montre que les magmas, qui ont formé ce complexe plutonique, font partie d'un volcanisme d'arc. Celui-ci se forme lorsqu'une plaque océanique plonge sous une plaque continentale. Les géologues appellent ce processus « subduction ». Dans un tel scénario, le manteau terrestre, qui se fait prendre entre ces deux plaques, fond pour former ainsi du magma. Ce magma remonte à travers la plaque continentale vers la surface. Si celui-ci atteint la surface, il forme les roches volcaniques, comme par exemple des laves. S'il n'atteint pas la surface, le magma se refroidit pour former finalement les roches plutoniques.Le long de la marge ouest d'Amérique du Sud, la plaque Nazca - qui se situe au sud-est de la plaque océanique pacifique - passe en dessous de la plaque d'Amérique du Sud. La bordure ouest du sud de la plaque sud-américaine a également été affectée par d'autres processus tectoniques, tels que des changements dramatiques dans les déplacements de plaques (il y a 25Ma) et la collision de la ride du Chili (depuis 15 Ma jusqu'à aujourd'hui). Ces caractéristiques tectoniques et magmatiques font de cette région un haut lieu pour les géologues. La plaque Nazca, s'est formée suite à l'ouverture d'une plaque océanique plus ancienne, il y a 25Ma. Cette ouverture est liée aux vitesses de subduction les plus rapides jamais connues. La ride du Chili est l'endroit où le sol de l'Océan Pacifique s'ouvre, formant deux plaques océaniques : les plaques Nazca et Antarctique. La ride du Chili subducte sous la plaque sud-américaine depuis 15Ma, en association avec la formation de grands volumes de magma ainsi que des changements morphologiques importants. La question de savoir lequel de ces changements tectoniques globaux affecte la géologie et la géographie de Patagonie a été, et est encore, discutée pendant de nombreuses années. De nombreux chercheurs suggèrent que la plupart des caractéristiques morphologiques et magmatiques en Patagonie sont liés à la subduction de la ride du Chili, mais cette suggestion est encore débattue comme le montre notre étude.Le batholithe de Patagonie du sud (SPB) est un énorme massif composé de roches plutoniques et il s'étend tout au long de la côte ouest de Patagonie (au sud de 47°S). Ces roches correspondent certainement aux racines d'un ancien arc volcanique, qui a été soulevé et érodé. Le CHPC, ainsi que d'autres petites intrusions dans la région, se situe dans une position exotique, à 100km à l'est du SPB. Certains chercheurs suggèrent que ces intrusions pourraient être liées à la subduction de la ride du Chili.Afin de débattre de cette problématique, nous avons utilisé différentes méthodes géochronologiques pour déterminer l'âge du CHPC et le comparer (a) à l'âge des roches intrusives similaires du SPB et (b) à l'âge de la collision de la ride du Chili. Dans ce travail, nous prouvons que le CHPC s'est formé au moins 7Ma avant la collision avec la ride du Chili. Sur la base des âges du CHPC et de la composition chimique de ses roches et minéraux, nous proposons que le CHPC fait partie d'un arc volcanique ancien. La migration de l'arc volcanique plus profondément dans le continent résulte de la grande vitesse de subduction entre 25 et lOMa. Des caractéristiques évidentes pour un tel processus - telles qu'une déformation importante et une vitesse d'érosion élevée - peuvent être rencontrées tout au long de la bordure ouest de l'Amérique du sud.

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For a variety of reasons, the concrete construction industry is not sustainable. First, it consumes huge quantities of virgin materials. Second, the principal binder in concrete is portland cement, the production of which is a major contributor to greenhouse gas emissions that are implicated in global warming and climate change. Third, many concrete structures suffer from lack of durability which has an adverse effect on the resource productivity of the industry. Because the high-volume fly ash concrete system addresses all three sustainability issues, its adoption will enable the concrete construction industry to become more sustainable. In this paper, a brief review is presented of the theory and construction practice with concrete mixtures containing more than 50% fly ash by mass of the cementitious material. Mechanisms are discussed by which the incorporation of high volume of fly ash in concrete reduces the water demand, improves the workability, minimizes cracking due to thermal and drying shrinkage, and enhances durability to reinforcement corrosion, sulfate attack, and alkali-silica expansion. For countries like China and India, this technology can play an important role in meeting the huge demand for infrastructure in a sustainable manner.

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We argue that long term sustainability of social security systems requires not only better equilibrium between the proportion in retirement and in employment but also an equitable distribution of the additional financial burden that aging inevitably will require. We examine how a proportional fixed ratios model of burden sharing between the aged and non-aged will establish inter-generational equity. Additionally we address the question of intra-generational equity and argue that the positive association between lifetime income and longevity requires more progressive financing of pensions and of care for the elderly.

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Postmortem chemistry is becoming increasingly essential in the forensic pathology routine and considerable progress has been made over the past years. Biochemical analyses of vitreous humor, cerebrospinal fluid, blood and urine may provide significant information in determining the cause of death or in elucidating forensic cases. Postmortem chemistry may essentially contribute in the determination of the cause of death when the pathophysiological changes involved in the death process cannot be detected by morphological methods (e.g. diabetes mellitus, alcoholic ketoacidosis and electrolytic disorders). It can also provide significant information and useful support in other forensic situations, including anaphylaxis, hypothermia, sepsis and hormonal disturbances. In this article, we present a review of the literature that covers this vast topic and we report the results of our observations. We have focused our attention on glucose metabolism, renal function and electrolytic disorders.

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Water inflows in the Gotthard Highway Tunnel and in the Gotthard Exploration Tunnel are meteoric waters infiltrating at different elevations, on both sides of an important orographic divide. Limited interaction of meteoric waters with gneissic rocks produces Ca-HCO3 and Na-Ca-HCO3 waters, whereas prolonged interaction of meteoric waters with the same rocks generates Na-HCO3 to Na-SO4 waters. Waters circulating in Triassic carbonate-evaporite rocks have a Ca-SO4 composition. Calcium-Na-SO4 waters are also present. They can be produced through interaction of either Na-HCO3 waters with anhydrite or Ca-SO4 waters with a local gneissic rock, as suggested by reaction path modeling. An analogous simulation indicates that Na-HCO3 waters are generated through interaction of Ca-HCO3 waters with a local gneissic rock. The two main SO4-sources present in the Alps are leaching of upper Triassic sulfate minerals and oxidative dissolution of sulfide minerals of crystalline rocks. Values of delta S-34(SO4) < <similar to>+ 9 parts per thousand, are due to oxidative dissolution of sulfide minerals, whereas delta S-34(SO4) > similar to+ 9 parts per thousand are controlled either by bacterial SO4 reduction or leaching of upper Triassic sulfate minerals. Most waters have temperatures similar to the expected values for a geothermal gradient of 22 degreesC/km and are close to thermal equilibrium with rocks. However relatively large, descending flows of cold waters and ascending flows of warm waters are present in both tunnels and determine substantial cooling and heating, respectively, of the interacting rocks. The most import upflow zone of warm, Na-rich waters is below Guspisbach, in the Gotthard Highway Tunnel, at 6.2-9.0 km from the southern portal. These warm waters have equilibrium temperatures of 65-75 degreesC and therefore constitute an important low-enthalpy geothermal resource. (C) 2001 Elsevier Science Ltd. All rights reserved.

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The defaults of Philip II have attained mythical status as the origin of sovereign debt crises. Four times during his reign the king failed to honor his debts and had to renegotiate borrowing contracts. In this paper, we reassess the fiscal position of Habsburg Spain. New archival evidence allows us to derive comprehensive estimates of debt and revenue. These show that primary surpluses were sufficient to make the king's debt sustainable in most scenarios. Spain's debt burden was manageable up to the 1580s, and its fiscal position only deteriorated for good after the defeat of the "Invincible Armada." We also estimate fiscal policy reaction functions, and show that Spain under the Habsburgs was at least as "responsible" as the US in the 20th century or as Britain in the 18th century. Our results suggest that the outcome of uncertain events such as wars may influence on a history of default more than strict adherence to fiscal rules.

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The thermal springs of Acquarossa and the nearby mineral springs of Soia have outlet temperatures of 12 degrees to 25 degrees C, TDS of 2290 to 3000 mg/kg and Ca-SO4 to Ca-SO4-HCO3 composition. Chemical geothermometers suggest reservoir temperatures close to 60 degrees C. P-CO2 values at depth are estimated to range from 0.3 to 2 bar. delta D and delta(18)O values indicate a meteoric origin and recharge elevations of 1600 +/- 150 m above sea level (a.s.l.) for these thermal and mineral waters. All these waters discharge from the overturned limb of the Simano nappe, probably dose to the contact between basement and underlying cover rocks. They therefore represent rain waters that descend slowly, heat at depth and locally rise relatively quickly to the surface, preserving part of their physical and chemical characteristics. (C) 1999 CNR. Published by Elsevier Science Ltd. All rights reserved.

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Cape Verde, located off the coast of Senegal in western Africa, is a volcanic archipelago where a combination of human, climatic, geomorphologic and pedologic factors has led to extensive degradation of the soils. Like other Sahelian countries, Cape Verde has suffered the effects of desertification through the years, threatening the livelihood of the islands population and its fragile environment. In fact, the steep slopes in the ore agricultural islands, together with semi-arid and arid environments, characterized by an irregular and poorly distributed rainy season, with high intensity rainfall events, make dryland production a challenge. To survive in these fragile conditions, the stabilization of the farming systems and the maintenance of sustainable yields have become absolute priorities, making the islands an erosion control laboratory. Soil and water conservation strategies have been a centerpiece of the government0s agricultural policies for the last half century. Aiming to maintain the soil in place and the water inside the soil, the successive governments of Cape Verde have implemented a number of soil and water conservation techniques, the most common ones being terraces, half moons, live barriers, contour rock walls, contour furrows and microcatchments, check dams and reforestation with drought resistant species. The soil and water conservation techniques implemented have contributed to the improvement of the economical and environmental conditions of the treated landscape, making crop production possible, consequently, improving the livelihood of the people living on the islands. In this paper, we survey the existing soil and water conservation techniques, analyze their impact on the livelihood condition of the population through a thorough literature review and field monitoring using a semi-quantitative methodology and evaluate their effectiveness and impact on crop yield in the Ribeira Seca watershed. A brief discussion is given on the cost and effectiveness of the techniques to reduce soil erosion and to promote rainfall infiltration. Finally, we discuss the critical governance factors that lead to the successful implementation of such strategy in a country with scarce natural resources.

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Oil palm is a significant and developing crop in many developing countries. The introduction of oil palm puts pressure on natural resources because it is often planted in cleared-cut land that previously supported other crops or was forested. This has led to environmental concerns which require attention. Hence it is important that new plantations are managed in a sustainable way to reduce the impact of oil palm cultivation on ecosystems whilst maximising yield and productivity to farmers. The application of arbuscular mycorrhizal fungi (AMF) technology is one option that can benefit both agronomic plant health and ecosystems. AMF have the potential to increase conventional agricultural productivity and are crucial for the sustainable functioning of agricultural ecosystems. This paper provides an insight into how AMF application might benefit oil palm cultivation through more sustainable management and the practical use of AMF for oil palm plantations.

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The defaults of Philip II have attained mythical status as the origin of sovereigndebt crises. We reassess the fiscal position of Habsburg Castile, derivingcomprehensive estimates of revenue, debt, and expenditure from new archivaldata. The king s debts were sustainable. Primary surpluses were large and rising.Debt-to-revenue ratios remained broadly unchanged during Philip s reign.Castilian finances in the sixteenth century compare favorably with those of otherearly modern fiscal states at the height of their imperial ambitions, includingBritain. The defaults of Philip II therefore reflected short-term liquidity crises,and were not a sign of unsustainable debts.

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The choice for suitable places for female mosquitoes to lay eggs is a key-factor for the survival of immature stages (eggs and larvae). This knowledge stands out in importance concerning the control of disease vectors. The selection of a place for oviposition requires a set of chemical, visual, olfactory and tactile cues that interact with the female before laying eggs, helping the localization of adequate sites for oviposition. The present paper presents a bibliographic revision on the main aspects of semiochemicals in regard to mosquitoes' oviposition, aiding the comprehension of their mechanisms and estimation of their potential as a tool for the monitoring and control of the Culicidae.