998 resultados para PCM wall
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In the present work, the electrochemical properties of single-walled carbon nanotube buckypapers (BPs) were examined in terms of carbon nanotubes nature and preparation conditions. The performance of the different free-standing single wall carbon nanotube sheets was evaluated via cyclic voltammetry of several redox probes in aqueous electrolyte. Significant differences are observed in the electron transfer kinetics of the buckypaper-modified electrodes for both the outer- and inner-sphere redox systems. These differences can be ascribed to the nature of the carbon nanotubes (nanotube diameter, chirality and aspect ratio), surface oxidation degree and type of functionalities. In the case of dopamine, ferrocene/ferrocenium, and quinone/hydroquinone redox systems the voltammetric response should be thought as a complex contribution of different tips and sidewall domains which act as mediators for the electron transfer between the adsorbate species and the molecules in solution. In the other redox systems only nanotube ends are active sites for the electron transfer. It is also interesting to point out that a higher electroactive surface area not always lead to an improvement in the electron transfer rate of various redox systems. In addition, the current densities produced by the redox reactions studied here are high enough to ensure a proper electrochemical signal, which enables the use of BPs in sensing devices.
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The crisis in the eurozone has had a dramatic impact on the economic and social fabric of European countries. However important it may be, the economic dimension is only the symptom of a broader problem. The crisis is primarily political in nature. Lorenzo Bini Smaghi argues in this book that the crisis reflects the inability of western democracies to solve problems that have been building for over two decades. He finds that democratically elected officials are loathe to take unpopular decisions that could jeopardise their re-election. Emergency thus becomes the engine of political action, and the justification for corrective measures vis-à-vis the voters. As a consequence, the cure in the form of austerity, administered belatedly and under pressure from the markets, becomes even more painful and unpopular, giving rise to populist movements and endangering democracy itself.
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Mode of access: Internet.
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On title page: With 98 illustrations of old and modern work.
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Texas State Department of Highway and Public Transportation, Transportation Planning Division, Austin
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National Highway Traffic Safety Administration, Washington, D.C.
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Boscotrecase, Italy; fresco on black ground
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Pompeii (deserted settlement), Italy
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Liaoning. Faku. Yemaotai; hanging scroll, ink and colors on silk
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Boscoreale, Italy; fresco