4 resultados para Planets and satellites: dynamical evolution and stability

em RUN (Repositório da Universidade Nova de Lisboa) - FCT (Faculdade de Cienecias e Technologia), Universidade Nova de Lisboa (UNL), Portugal


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Febs Journal (2009)276:1776-1786

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Dissertation presented to obtain a PhD degree in Biochemistry at Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa

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Self-assembly is a phenomenon that occurs frequently throughout the universe. In this work, two self-assembling systems were studied: the formation of reverse micelles in isooctane and in supercritical CO2 (scCO2), and the formation of gels in organic solvents. The goal was the physicochemical study of these systems and the development of an NMR methodology to study them. In this work, AOT was used as a model molecule both to comprehensively study a widely researched system water/AOT/isooctane at different water concentrations and to assess its aggregation in supercritical carbon dioxide at different pressures. In order to do so an NMR methodology was devised, in which it was possible to accurately determine hydrodynamic radius of the micelle (in agreement with DLS measurements) using diffusion ordered spectroscopy (DOSY), the micellar stability and its dynamics. This was mostly assessed by 1H NMR relaxation studies, which allowed to determine correlation times and size of correlating water molecules, which are in agreement with the size of the shell that interacts with the micellar layer. The encapsulation of differently-sized carbohydrates was also studied and allowed to understand the dynamics and stability of the aggregates in such conditions. A W/CO2 microemulsion was prepared using AOT and water in scCO2, with ethanol as cosurfactant. The behaviour of the components of the system at different pressures was assessed and it is likely that above 130 bar reverse microemulsions were achieved. The homogeneity of the system was also determined by NMR. The formation of the gel network by two small molecular organogelators in toluene-d8 was studied by DOSY. A methodology using One-shot DOSY to perform the spectra was designed and applied with success. This yielded an understanding about the role of the solvent and gelator in the aggregation process, as an estimation of the time of gelation.

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The European Union has taken in recent years an increasingly important role in ensuring peace and stability in the international community, and the security and defence policy of the Union has become synonymous with crisis management. The Union has addressed the issue of crisis management through two sources: the military side and the civilian side, which consists in carrying out numerous crisis management operations and missions. This study discusses the role of the European Union in conducting crisis management operations and missions and how the gendarmerie forces contribute to the success of the same. It will discuss the evolution of the European Union's security policy and the concept of crisis management, and seek to demonstrate the added value of the commitment of gendarmerie forces in operations and missions of crisis management, particularly with regard to employment of the European Gendarmerie Force. On the other hand, it will study the planning process for crisis management of the European Union, featuring the entities and agencies involved in it, and presenting the products that result from this same process. The use of Gendarmerie forces in crisis management operations and missions has significant advantages. Its use is recommended to post - conflict scenarios, in complementarity with the armed forces, in order to overcome the "security gap" that mediates the transition from the state of conflict for the period of peace and reconstruction. Gendarmerie forces can also be engaged both in military crisis management operations and civilian crisis management missions.