996 resultados para Grain trade.


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Using first principles electronic structure methods, we calculate the effects of boron impurities in bulk copper and at surfaces and grain boundaries. We find that boron segregation to the Sigma5(310)[001] grain boundary should strengthen the boundary up to 1.5 ML coverage (15.24 at./nm2). The maximal effect is observed at 0.5 ML and corresponds to boron atoms filling exclusively grain boundary interstices. In copper bulk, B causes significant distortion both in interstitial and regular lattice sites, for which boron atoms are either too big or too small. The distortion is compensated to a large extent when the interstitial and substitutional boron combine together to form a strongly bound dumbbell. Our prediction is that bound boron impurities should appear in a sizable proportion if not dominate in most experimental conditions. A large discrepancy between calculated heats of solution and experimental terminal solubility of B in Cu is found, indicating either a significant failure of the density functional approach or, more likely, strongly overestimated solubility limits in the existing B-Cu phase diagram.

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Does the World Trade Organization function to reinforce American dominance (or hegemony) of the world economy? We examine this question via an analysis of trade disputes involving the United States. This allows us to assess whether the US does better than other countries in this judicialised forum: and in so doing enhance the competitive prospects of their firms. The results are equivocal. The United States does best in the early phases of a dispute, where political power is important. It does less well as the process develops.

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The chaotic profile of dust grain dynamics associated with dust-acoustic oscillations in a dusty plasma is considered. The collective behaviour of the dust plasma component is described via a multi-fluid model, comprising Boltzmann distributed electrons and ions, as well as an equation of continuity possessing a source term for the dust grains, the dust momentum and Poisson's equations. A Van der Pol–Mathieu-type nonlinear ordinary differential equation for the dust grain density dynamics is derived. The dynamical system is cast into an autonomous form by employing an averaging method. Critical stability boundaries for a particular trivial solution of the governing equation with varying parameters are specified. The equation is analysed to determine the resonance region, and finally numerically solved by using a fourth-order Runge–Kutta method. The presence of chaotic limit cycles is pointed out.

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1. We examine whether various measures of herbivore current physiological state (age, breeding and immune status) and genetic potential can be used as indicators of exposure to and risk from disease. We use dairy cattle and the risks of tuberculosis (TB) transmission posed to them by pasture contaminated with badger excreta (via the fecal-oral route) as a model system to address our aim.

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The notion that the EU is a trade power is central to studies of the Union’s international presence. Credible threats to withhold access to Europe’s markets are said to provide the Union with leverage in respect of other trade partners. This paper queries the continuing ability of the European Union to act effectively this way. The current Doha malaise is a symptom of deeper changes in the international trade system. As emerging markets become more affluent and participate in foreign direct investment, their interest in market access per se become less important relative to other areas of regulation.

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This study focuses on British attempts during the nineteenth century to outlaw the Atlantic Slave Trade internationally, for which it was successful, after seventy-five years of effort. It considers the lack of willingness to allow Great Britain, at the Congress of Vienna and during the Concert of Europe, to establish a universal treaty outlawing the slave trade. As a result, this mandated a change in British tactics, which would ultimately prove to be successful – the establishment of a web of bilateral agreements which came to included all maritime powers. The study then moves on to consider the evolution of these bilateral agreements while highlighting the relationship between Great Britain and States (Brazil, France, Portugal and the United States) which were obstinate in their willingness to join this bilateral regime. Finally, consideration is given to the move towards the establishment of the 1890 General Act of Brussels; and thus the conclusion of the decades long British foreign policy objective of a universal instrument meant to suppress the Atlantic Slave Trade.