192,385 research outputs found
Raízes integralistas da teoria tridimensional do direito: história das ideias de Miguel Reale (1933-1953)
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Jurídicas, Programa de Pós-Graduação em Direito, Florianópolis, 2014.Este trabalho narra a história das ideias jurídicas de Miguel Reale, jurista e filósofo brasileiro, desde sua adesão ao Integralismo (1933) até a publicação de ?Filosofia do Direito? (1953). A pesquisa centrou-se na interpretação das ?Memórias? do autor (1987), em cotejo com suas obras sobre Integralismo, Teoria do Direito, Teoria do Estado, Filosofia Política e Filosofia do Direito. Também foi realizada pesquisa empírica sobre o diário integralista ?Acção?, dirigido por Reale de 1936 a 1938, cujos exemplares encontram-se microfilmados no Arquivo Público do Estado de São Paulo. As trajetórias intelectual e política do autor foram analisadas conjuntamente, mediante métodos da historiografia e da sociologia dos intelectuais, apoiados nas categorias analíticas de Michel Foucault e Pierre Bourdieu.Abstract : This work is a historical narrative about juridical ideas of Professor Miguel Reale, a brasilian jurist and philosopher, from the time he became involved with the political movement known as ?Integralismo? (1933) until the publication of ?Filosofia do Direito? (1953). This research was based on my interpretation of Reale?s memories (?Memórias?, from 1987), in comparison with his works about ?Integralismo?, Theory of Law, Theory of State, Political Philosophy and Philosophy of Law. In adition to this, it contains an empirical research about ?Acção?, an integralist newspaper directed by Reale between 1936 and 1938. Nowadays, this material is microfilmed in the ?Arquivo Público do Estado de São Paulo?, the State of São Paulo?s Public Archive. The intellectual and political trajectories of the author were analyzed altogether, through the methods of historiography and sociology of intellectuals. Some analytical categories created by Michel Foucault and Pierre Bourdieu were used to achieve this purpose
A high-power and fast charging Li-ion battery with outstanding cycle-life
No full textElectrochemical energy storage devices based on Li-ion cells currently power almost all electronic devices and power tools. The development of new Li-ion cell configurations by incorporating innovative functional components (electrode materials and electrolyte formulations) will allow to bring this technology beyond mobile electronics and to boost performance largely beyond the state-of-the-art. Here we demonstrate a new full Li-ion cell constituted by a high-potential cathode material, i.e. LiNi0.5Mn1.5O4, a safe nanostructured anode material, i.e. TiO2, and a composite electrolyte made by a mixture of an ionic liquid suitable for high potential applications, i.e. Pyr1,4PF6, a lithium salt, i.e. LiPF6, and standard organic carbonates. The final cell configuration is able to reversibly cycle lithium for thousands of cycles at 1000 mAg-1 and a capacity retention of 65% at cycle 2000. © 2017 The Author(s)
Applicazioni innovative della NMR per la caratterizzazione della pappa reale
No full textSviluppo di un metodo alternativo per caratterizzare la qualità della pappa reale e provenienza da una determinata zona geografica. La tecnica NMR verrà confrontata con i metodi di analisi classica sia per valutarne le potenzialità sia per l'ottenimento di informazioni complementari
H2 thermal desorption and hydride conversion reactions in Li cells of TiH2/C amorphous nanocomposites
No full textHere we investigate the properties of amorphous TiH2/carbon nanocomposites as possible active material in lithium cells. Several TiH2/C mixtures are prepared by a mechanochemical route, by varying the carbon/hydride ratio. Materials are tested in electrochemical cells versus lithium metal in EC:DMC LiPF6 electrolyte by galvanostatic cycling (GC) and are characterized by X-ray diffraction, transmission electron microscopy, thermogravimetry and mass spectrometry. Thermal dehydrogenation processes are altered by the mechanochemical treatment of the sample: milling decreases the hydrogen content of the hydride. On the other hand, the mechanochemical grinding increases the specific capacity delivered during the first GC discharge. We suggest that the electrochemical process is the result of a delicate balance between the absolute quantity of hydrogen and its availability for the hydride conversion reaction. © 2015 Elsevier B.V
Origin of the Voltage Hysteresis of MgH2 Electrodes in Lithium Batteries
No full textMagnesium hydride has been proposed as innovative anode material for Li ion cells due to its large theoretical capacity and high-energy efficiency compared to other conversion materials. In this work, we report a combined experimental-theoretical study about the origin of voltage hysteresis in the conversion reaction of MgH2 in lithium cells. Experimentally, the extent of the thermodynamic voltage hysteresis in the first galvanostatic discharge-charge cycle has been determined by the GITT technique and decoupled from the kinetic overpotentials. Theoretically, the origin of the thermodynamic voltage hysteresis has been evaluated and studied by means density functional theory calculations within the supercell approach. Different elementary reactions have been modeled upon reduction and oxidation on the surfaces of the active phases (i.e., MgH2, LiH, and Mg), and the associated theoretical voltages have been predicted. Experimental and theoretical results have been compared and discussed to draw a comprehensive description of the elementary surface reactions of the MgH2 conversion in lithium cells. © 2015 American Chemical Society
Lightweight borohydrides electro-activity in lithium cells
No full textAs a substitute for graphite, the negative electrode material commonly used in Li-ion batteries, hydrides have the theoretical potential to overcome performance limits of the current state-of-the-art Li-ion cells. Hydrides can operate through a conversion process proved for some interstitial hydrides like MgH2: MxAy+ n Li = x M + y LimA, where m = n/y. Even if far from optimization, outstanding performances were observed, drawing the attention to the whole hydride family. Looking for high capacity systems, lightweight complex metal hydrides, such as borohydrides, deserve consideration. Capacities in the order of 2000-4000 mAh/g can be theoretically expected thanks to the very low formula unit weight. Although the potential technological impact of these materials can lead to major breakthroughs in Li-ion batteries, this new research field requires the tackling of fundamental issues that are completely unexplored. Here, our recent findings on the incorporation of borohydrides are presented and discussed. © 2016 by the authors
Magnesium hydride as negative electrode active material in lithium cells: A review
No full textMgH2 has been recently proposed in 2008 as novel conversion material for negative electrodes in lithium ion cells (LIC). Since then, many aspects of the electrochemical behaviour in LIC of this material have been investigated: both experimental and computational studies have been carried out to investigate the fundaments of the MgH2 conversion reaction and to demonstrate performances in LIC close to the theoretical predictions (2037 mAh g−1 and 2842 mAh cm−3). The conversion process involves a reversible redox reaction where the pristine binary hydride is electrochemically reduced to magnesium nanoparticles surrounded by a LiH matrix, and oxidized back to MgH2. In recent years the research efforts on this material have been focused on: (a) the identification of successful synthetic routes to achieve good performances in LIC; (b) the understanding of the basics of the MgH2 conversion reaction; (c) the optimization of technological aspects to improve the performances in LIC (e.g. electrode formulation assessment and adoption of solid electrolytes). In this paper we present a comprehensive review about the research studies reported in the literature concerning the use of MgH2 as negative electrode for lithium ion cells. © 2017 Elsevier Lt
A mixed mechanochemical-ceramic solid-state synthesis as simple and cost effective route to high-performance LiNi0.5Mn1.5O4 spinels.
No full textThe implementation of high potential materials as positive electrodes in high energy Li-ion batteries requires to develop scalable and smart synthetic routes. In the case of the LiNi0.5Mn1.5O4 (LNMO) spinel material, a successful preparation strategy must drive the phase formation in order to obtain structural, morphological and surface properties capable to boost performances in lithium cells and minimize the electrolyte degradation. Here we discuss a novel simple and easily scalable mechanochemical synthetic route, followed by a high temperature annealing in air, to prepare LMNO materials starting from oxides. A synergic doping with chromium and iron has been incorporated, resulting in the spontaneous segregation of a CrOx-rich surface layer. The effect of the annealing temperature on the physico-chemical properties of the LMNO material has been investigated as well as the effect on the performances in Li-cells. © 2017 Elsevier Lt
I giardini del Palazzo Reale, dai piaceri della corte a una progressiva integrazione con la città
No full textIl complesso articolato in Teatro di Corte, Galleria, Accademia Reale, Scuderie e cavallerizze si affaccia sul Giardino del Palazzo Reale, il cui ampliamento è possibile grazie all'espansione verso est della città. Inizialmente gli accademisti utilizzano una parte dell'area, dove è anche allestita una cavallerizza. Dal 1697 tutta l'area viene ridisegnata su progetto di André Le Notre
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