872 research outputs found
Adsorption of Eu(III) onto Minerals in the Presence of Humic Acids: Effects of Various Solution Parameters and Sorptive Fractionation on Modelling and Spectroscopy
No full textInternational audienceAdsorption of metals on minerals with humic acids is always under predicted [1]. The case of Eu(III) in ternary system including purified Aldrich humic acid (PAHA) and alpha-Al2O3 was measured, modelled and probed using time-resolved laser-induced luminescence spectroscopy (TRLS). Each binary system was studied independently [2,3,4], and the luminescence properties of Eu(III), luminescence spectra and decay times (%), were aquired and compared [5]. Influence of ionic strength and PAHA concentration was also evaluated.The typical luminescence behaviour of Eu(III)-HA system, showing a bi-exponential decay, was also found in the ternary system Eu(III)/PAHA/'- Al2O3, but with marked differences. Luminescence spectra and faster decay %1 are the same in both system at pH 6, modifications of Eu(III) luminescence spectra and decrease of %2 are showing a progressive influence of '-Al2O3. The non-variation of %1suggests the on-going influence of PAHA, notwithstanding its progressive desorption. Comparing with previous data on sorptive fractionation of PAHA [2,3,6], and with the TRLS evolution of the system [5], an operational modelling was proposed [4], which implies that alumina-sorbed PAHA is showing a stronger interaction towards Eu(III) compared with non-sorbed PAHA even at pH > 7. This stronger interaction is due to the sorptive fractionation which reveals stronger binding sites [1,4,7]. [1] Reiller (2012) Miner. Mag.76, 2643-2658; [2] Janot, Reiller, Korshin, Benedetti (2010) Environ. Sci. Technol.44, 6782-6788; [3] Janot, Reiller, Zheng, Croué, Benedetti (2012) Water Res.46, 731-740; [4] Janot, Reiller, Benedetti (2013), Colloids Surf. A, DOI: 10.1016/j.colsurfa.2013.02.052.; [5] Janot, Benedetti, Reiller (2011) Environ. Sci. Technol.45, 3224-3230; [6] Reiller, Amekraz, Moulin (2006) Environ. Sci. Technol.40, 2235-2241; [7] Tipping, Griffith, Hilton (1983) Croat. Chim. Acta56, 613-621
Study of CaUO(CO) complexes using CE-ICP-MS with polyetheretherketone (PEEK) capillaries
No full textInternational audienceThe formation constants of CaUO(CO) complexes were determined directly using capillary electrophoresis coupled with inductively coupled plasma mass spectrometry (CE-ICP-MS) in 0.1 M NaCl and at room temperature. Instead of conventional fused silica, polyetheretherketone (PEEK), a neutral organic material, was used as the capillary material to avoid interactions between uranyl and silica. Since PEEK is not optically transparent, a macrocyclic neutral complex, Ga-NOTA, was used to measure the electroosmotic flux directly by ICP-MS. The impact of the Joule effect was evaluated to control the temperature during electrophoresis. To alter the reversible interaction that arose from continuous use, a two-mode electrophoresis strategy was adopted. The observed mobilities of the samples showed a satisfactory correlation with the theoretical charge calculated from previous data (C. Shang and P. E. Reiller, Dalton Trans., 2020, 49, 466–481). The successive formation constants obtained in this work, log K(CaUO(CO)) = 5.28 ± 0.39 and log K(CaUO(CO)(aq)) = 8.46 ± 0.67 in 0.1 M NaCl, were extrapolated to infinite dilution using the Davies equation, yielding log β°(CaUO(CO)) = 27.12 ± 0.39 and log β°(CaUO(CO)(aq)) = 30.30 ± 0.67. These values are in excellent agreement with Shang and Reiller (C. Shang and P. E. Reiller, Dalton Trans., 2020, 49, 466–481). This further verifies the thermodynamic data available for these species and validates PEEK-based capillary electrophoresis for the measurement of thermodynamic constants of inorganic complexes in alkaline media
Prefazione a Pascal e la filosofia
No full textThe author presents the distinctive features of the work "Pascal e la filosofia"
Samuel Beckett and the Writers of Port-Royal
No full textIt has been observed that ‘the literary influences on Beckett have been far more important than has been acknowledged, and more important indeed, than the philosophical influences’ (Smith 2002: 3). The truth of this statement is evidenced by the description that scholars have given of Samuel Beckett’s relationship to seventeenth century French classicism. To date, critical interest has been limited for the most part to the figure of the philosopher René Descartes on the (fragile) grounds that Beckett was exclusively concerned with the Cartesian imperative of clarity and order, the fundamental dualism between body and mind, and Nominalism.
Together with the assumption that Beckett’s vision was essentially Cartesian, his literary filiation with Pascal was suggested by critics, but only in terms of Beckett’s formal approach to the theatre. In his short article on En attendant Godot in 1953, the playwright Jean Anouilh was among the first reviewers to suggest that Beckett’s drama synthesizes the encounter between ‘classicism’ and a ‘modern’ form of art. It is well known that Beckett retained a lifelong admiration for Pascal – indeed, Pascal was one of his ‘old chestnuts’ (Knowlson 1997: 653). Little attention has been paid, however, to the originality of Pascal’s thought, the specific nature of his prose, and the impact these might have had upon Beckett’s mature work, especially the trilogy and the subsequent short prose. Yet, in the literary and philosophical context of post-war France, Beckett’s filiation with Pascal, their corresponding preoccupations, were evident to his contemporaries, who identified Pascal as an underlying presence in his works
Platone per disporre a Pascal
No full textPrendendo spunto dal frammento di Pascal «Platone per disporre al cristianesimo», l’autrice intercetta una nuova disposizione di Platone a Pascal, basata sull’ordine dell’amore che per entrambi è centrale. Questa operazione ha un duplice scopo: consentire a Pascal di essere incluso nel campo della filosofia e valorizzare l’invenzione platonica della philo-sophiaTaking a cue from Pascal’s fragment «Platon pour disposer au christia- nisme», the author sets a new disposition of Plato to Pascal, based on the order of love that both philosophers present. This operation has a double philosophical aim: to allow Pascal to be included in the field of philosophy and to valorise the Platonic invention of philo-sophia
FERNANDO PESSOA READER OF PASCAL AND THE PROJECT OF THE BOOK OF DISQUIET
No full textO presente artigo visa explorar as relações entre Pascal e Pessoa tendo por base o impacto da obra do autor francês tanto na estruturação quanto nas temáticas presentes ao longo do projeto do Livro do Desassossego. Com efeito, na Biblioteca Particular de Pessoa encontramos livros de e sobre Pascal que se encontram sublinhados e anotados pelo autor português e nos possibilitam certificar o interesse de Pessoa pelo pensamento pascaliano. Para além disso, o espólio de Pessoa oferece-nos um conjunto de fragmentos que nos permitem elucidar até que ponto a leitura da obra de Pascal viria a ser importante para a elaboração dos fragmentos do Livro do Desassossego. Assim, tendo por base a análise da presença do nome e do pensamento de Pascal em fragmentos do espólio de Pessoa, o presente artigo explicita qual o papel da leitura pessoana de Pascal na elaboração do projeto do Livro do DesassossegoThis article aims to explore the relations between Pascal and Pessoa based on the impact of the work of the French author both in the structure and the themes present throughout the Book of Disquiet. Indeed, in the Pessoa’s Private Library one finds books of and about Pascal that are underlined and bear notes by the Portuguese author, which enable us to certify Pessoa’s interest in Pascal’s thought. In addition, Pessoa’s Archive offers us a set of fragments that allow us to elucidate the extent to which the reading of Pascal’s work would be important for the elaboration of fragments of the Book of Disquiet. Thus, based on the analysis of the presence of Pascal’s name and thought in fragments of Pessoa’s Archive, this article explains the role of Pessoa’s reading of Pascal in the preparation of the Book of Disquiet. 
The Hexagramma Mysticum of Pascal
No full textThis short essay about the hexagramma mysticum , the mystic hexagram , of Pascal-divided into two parts. The first contains a brief history concerning the hexagram, such as, its origin, its author, its influence upon other theorems. In the second part, a slight sketch of the more important theorems and properties of the mystic hexagram, and of some methods of obtaining them are given
The reasons of the heart: a study on the centrality of the heart in Pascal
No full textO conjunto de textos e fragmentos que compõem a obra de Blaise Pascal e também uma parte da tradição interpretativa deixam entender que há no pensamento deste filósofo certas cisões radicais. Assim, frequentemente, chega-se à conclusão de que, em maior ou menor grau, a filosofia de Pascal é fragmentada e descontínua. Por uma obra fragmentada ou descontínua, não entendemos aqui o inacabamento dos textos ou a estrutura em aforismos ou pequenas digressões aparentemente independentes (de fato presentes em Pascal), mas aquela obra a que falte um elemento comum entre os textos, a que falte o mínimo de continuidade temática e conexão argumentativa, ou seja, uma obra que careça de um solo mínimo para a leitura do conjunto de seus textos. Embora alguns temas em Pascal notadamente a doutrina das três ordens evoquem uma espécie de cisão, isso não nos parece ser verdade quando tomamos seu pensamento na totalidade. Não é claro que o pensamento de Pascal careça totalmente de organização interna. Com efeito, ao lermos com mais atenção a obra pascaliana, tomamos consciência da originalidade e importância que tem, em seus escritos, o conceito de coração, entendido como a faculdade do sentimento. O que pensamos é que, embora não torne a filosofia do nosso autor um sistema fechado (à maneira cartesiana, por exemplo), o conceito de coração, na medida em que é definido pela capacidade de sentir seja aos princípios, seja a Deus , é capital na obra de Blaise Pascal e por isso nos oferece uma chave de leitura para entendermos os textos pascalianos em seu conjunto. Da ciência à teologia, passando pelo desejo de ser feliz e o divertimento, o conceito de coração cumpre papel central na filosofia de Pascal.The set of texts and fragments that make up the work of Blaise Pascal and also a part of the interpretative tradition lead to understand that there is in the thought of this philosopher certain radical decisions. So, often, one comes to the conclusion that, to a greater or lesser extent, the philosophy of Pascal is fragmented and discontinuous. For a fragmented or discontinuous work, we do not understand here incompleteness of the text or structure in aphorisms or small seemingly unrelated digressions (actually present in Pascal), but that work that lacks a common element between the texts, that lacks the minimum thematic continuity and argumentative connection, that is, a work that lacks a minimum ground for reading the set of their texts. Although some issues in Pascal - notably the doctrine of the three orders - evoke a kind of rupture, it does not seem to be true when we take his thoughts in full. It is not clear that the thought of Pascal totally lacks internal organization. Indeed, when we read with more attention Pascals work, we become aware of the originality and importance of, in his writings, the concept of \"heart\", understood as the faculty of feeling. What we think is that, though it doesnt make the philosophy of our author a closed system (in cartesian manner, for example), the concept of the heart, to the extent that is defined by the ability to feel - wether the principles, or God - is capital in the work of Blaise Pascal and therefore offers us a reading key to understand pascalian texts as a whole. From science to theology, through the desire to be happy and diversion, the concept of heart plays a central role in Pascal\'s philosophy
Relations entre structure et réactivité dans l’interaction entre les substances humiques, les polluants métalliques du cycle du nucléaire et les surfaces minérales
No full textThis document proposes an analysis of the structure-reactivity relationships in the interaction between humic substances, metallic pollutants from the nuclear cycle, and mineral surfaces. It composes the scientific document, which allowed the author to defend a habilitation degree. It is mainly focused on the research works into which the author have been involved in on this particular thematic. Humic substances are issued from the degradation of the living. They have an important influence onto migration of metals in the environment. They are showing particular intrinsic physic and chemical, metal complexation, and adsorption onto mineral surfaces properties, which render the global comprehension of the different mechanisms somehow difficult. These three aspects are covered in this document. The first part is dedicated to the studies on composition, structure, and organization of humic substances, which cannot be considered as a well-defined type of chemical. They are a heterogeneous degradation product with a supramolecular organization, which is showing fractal properties from fractions up to several nanometers. Second part is on the complexation reactions. The different modelling strategies come from the difficulties on apprehending composition, structure, and organization of humic substances. The different models used are showing more or less strongly empiric characteristics. They can be derived from the mass action law, or explicitly account for heterogeneity, acido-basic, or ionic strength related parameters. The third and latter part covers the adsorption studies. The main property is adsorptive fractionation, which induces modification of chemical composition of humic substances between the surface and the solution. It also induces modification of complexation properties between the adsorbed and non-adsorbed fractions. Because of adsorptive fractionation, and the particular influence of ionic strength on humic substances, and of complexed metals, adsorption, the studies on simple model molecules to represent humic substances reactivity are an illusion. The global comprehension will mainly be obtained from the understanding of dedicated studies.Ce document présente une analyse des relations entre structure et réactivité dans l’interaction entre les substances humiques, les polluants métalliques du cycle du nucléaire et les surfaces minérales. Il reprend le document scientifique qui a permis la soutenance d’une habilitation à diriger les recherches, et à ce titre se concentre principalement sur les recherches menées ou animées par l’auteur sur cette thématique. Les substances humiques sont issues de la dégradation du vivant, et possèdent une influence importante sur la migration des métaux dans l’environnement. Elles présentent des propriétés physico-chimiques intrinsèques, des capacités de complexation des métaux et d’adsorption sur les surfaces minérales qui font qu’une compréhension globale des différents mécanismes en jeu est souvent difficile. Ces trois aspects sont abordés dans ce document. La première partie est consacrée aux études sur la composition, la structure et l’organisation des substances humiques. Les substances humiques ne constituent pas un type de molécules chimiques bien définies, mais plutôt un mélange hétérogène de produits de dégradation, ayant une organisation supramoléculaire et fractale sur une grande échelle de taille, depuis la fraction de nanomètre jusqu’à plusieurs dizaines de nanomètres. La deuxième partie aborde les réactions de complexation. Les différentes stratégies de modélisation sont la conséquence des difficultés de compréhension de la composition, de la structure et de l’organisation. Les modèles utilisés possèdent des caractéristiques plus ou moins fortement empiriques. Ils peuvent être dérivés de la loi d’action des masses avec des paramètres extra-thermodynamiques, ou bien prendre en compte implicitement des paramètres liés à l’hétérogénéité, aux réactions acido-basiques, à la force ionique, et aux réactions de compétitions. La troisième et dernière partie couvre les études d’adsorption et les comportements particuliers des substances humiques. La propriété principale est le fractionnement par les surfaces qui induit des modifications de compositions des substances humiques entre la surface et la solution, et par la même des différences de propriétés de complexation des métaux entre fraction à la surface et en solution. Ce fractionnement, ainsi que l’influence particulière de la force ionique sur l’adsorption des substances humiques, et des métaux complexés, font qu’il est illusoire de vouloir représenter la réactivité des substances humiques par des composés organiques simples, et que la compréhension globale de ces systèmes ne peut être atteinte que par des études dédiées
Measurement of the D+/- production asymmetry in 7 TeV pp collisions
No full textThe asymmetry in the production cross-section \sigma of D+/- mesons, A_P = (\sigma(D+) - \sigma(D-))/(\sigma(D+) + \sigma(D-)), is measured in bins of pseudorapidity \eta and transverse momentum p_T within the acceptance of the LHCb detector. The result is obtained with a sample of D+ -> K_S pi+ decays corresponding to an integrated luminosity of 1.0 fb^-1, collected in pp collisions at a centre of mass energy of 7 TeV at the Large Hadron Collider. When integrated over the kinematic range 2.0 K_S pi+ decay is negligible. No significant dependence on \eta or p_T is observed
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