978 resultados para Lewis, Matthew, 1775-1818. The monk
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A general approach for the synthesis of fused cyclic systems containing medium-sized rings (7-9) has been developed. The key steps involve a diastereoface-selective Diels-Alder reaction of the dienophiles 4a-d attached to a furanosugar with cyclopentadiene and ring opening (ROM)-ring closing metathesis (RCM) of the resulting norbornene derivatives 10a-d and 11a-d. Diels-Alder reaction of the dienophiles 4a-d with cyclopentadiene in the absence of a catalyst produced 10a-d as the major product arising through addition of the diene to the unhindered Si-face. The most interesting and new aspect of the Diels-Alder reaction of these dienophiles is the accessibility of the Re-face that was blocked by the alkenyl chains under Lewis acid catalysis producing the diastereoisomers 11a-d exclusively. The reversal of facial selectivity from an uncatalyzed reaction to a catalyzed one is unprecedented. The observed stereochemical dichotomy is attributed to rotation of the enone moiety along the or bond linking the sugar moiety during formation of the chelate 13. This makes the Re-face of the enone moiety in 4a-d unhindered. Diels-Alder reaction of the carbocyclic analogue 15 under Lewis acid catalysis produced a 1: 1 mixture of the adducts 16 and 17 confirming the participation of sugar ring oxygen in chelate formation. Finally ROM-RCM of 10a-d and 11a-d with Grubbs' catalyst afforded the cis-syn-cis and cis-anti-cis bicyclo-annulated sugars 21a-d and 23a-d, respectively, containing 7-9 membered rings.
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The extent to which lactoperoxidase (LP) activity was affected while varying the concentration of various compounds normally present in the reaction medium was investigated. LP activity increased with increasing concentrations of 2,2'-azino-bis-3-ethylbenz-thiazoline-6-sulphonic acid (ABTS) but decreased with increasing thiocyanate concentrations. Maximum activity was at 0.1 mm for peroxide. Activity increased in the presence of lactose, whey protein concentrate, sodium, magnesium and calcium chlorides, but decreased in the presence of casein. Activity was similar in either acetate or phosphate buffers but higher in either citrate or succinate buffers. These compounds influence LP activity and should be considered when optimum activity conditions are being established.
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The inequality of nutrition and obesity re-focuses concern on who in society is consuming the worst diet. Identification of individuals with the worst of dietary habits permits for targeting interventions to assuage obesity among the population segment where it is most prevalent. We argue that the use of fiscal interventions does not appropriately take into account the economic, social and health circumstances of the intended beneficiaries of the policy. This paper reviews the influence of socio-demographic factors on nutrition and health status and considers the impacts of nutrition policy across the population drawing on methodologies from both public health and welfare economics. The effects of a fat tax on diet are found to be small and while other studies show that fat taxes saves lives, we show that average levels of disease risk do not change much: those consuming particularly bad diets continue to do so. Our results also suggest that the regressivity of the policy increases as the tax becomes focused on products with high saturated fat contents. A fiscally neutral policy that combines the fat tax with a subsidy on fruit and vegetables is actually more regressive because consumption of these foods tends to be concentrated in socially undeserving households. We argue that when inequality is of concern, population-based measures must reflect this and approaches that target vulnerable populations which have a shared propensity to adopt unhealthy behaviours are appropriate.
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The soluble phase of milk was separated at 20 and 80°C using ultrafiltration. The resulting permeates were then subjected to further ultrafiltration and dialysis at close to these two temperatures. It was found that pH, Ca2+ and soluble Ca decreased as the separation temperature increased both in original UF permeates and in dialysates obtained from these permeates, but P decreased only slightly. The major reason for these changes was due to the precipitation of calcium phosphate/citrate complexes onto the casein micelle with concomitant release of H+. The pH of both permeates and dialysates from milk at 20°C were slightly higher than for milk. When UF permeates collected at 20 and 80°C, were each dialysed at both these temperatures, the dialysate collected at 80°C showed much less temperature dependence for pH and ionic calcium compared with that collected at 20°C. This is in contrast to milk, which shows considerable temperature dependence for pH and ionic calcium. Further experiments revealed that the pH and Ca2+ concentration of permeates showed high temperature dependence above the temperature at which they were separated, but a much lower temperature dependence below that temperature. These findings suggest that dialysis and UF of milk at high temperature provide the best means yet for estimating the pH and ionic calcium of milk at that temperature.
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The removal of the most long-lived radiotoxic elements from used nuclear fuel, minor actinides, is foreseen as an essential step toward increasing the public acceptance of nuclear energy as a key component of a low-carbon energy future. Once removed from the remaining used fuel, these elements can be used as fuel in their own right in fast reactors or converted into shorter-lived or stable elements by transmutation prior to geological disposal. The SANEX process is proposed to carry out this selective separation by solvent extraction. Recent efforts to develop reagents capable of separating the radioactive minor actinides from lanthanides as part of a future strategy for the management and reprocessing of used nuclear fuel are reviewed. The current strategies for the reprocessing of PUREX raffinate are summarized, and some guiding principles for the design of actinide-selective reagents are defined. The development and testing of different classes of solvent extraction reagent are then summarized, covering some of the earliest ligand designs right through to the current reagents of choice, bis(1,2,4-triazine) ligands. Finally, we summarize research aimed at developing a fundamental understanding of the underlying reasons for the excellent extraction capabilities and high actinide/lanthanide selectivities shown by this class of ligands and our recent efforts to immobilize these reagents onto solid phases.
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This latest issue of the series of Typography papers opens with a beautifully illustrated article by the type designer Gerard Unger on ‘Romanesque’ letters. A further installment of Eric Kindel’s pathbreaking history of stencil letters is published in contributions by him, Fred Smeijers, and James Mosley. Maurice Göldner writes the first history of an early twentieth-century German typefounder, Brüder Butter. William Berkson and Peter Enneson recover the notion of ‘readability’ through a history of the collaboration between Matthew Luckiesh and the Linotype Company. Paul Luna discusses the role of pictures in dictionaries. Titus Nemeth describes a new form of Arabic type for metal composition. The whole gathering shows the remarkable variety and vitality of typography now.
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Dans cet article on examinera les cérémonies d'acclamation du roi D. João VI qui ont eu lieu à Tejuco en 1818. Le décodage de la riche variété d'images esthétiques présente dans ces célébrations peut être une stratégie privilégiée pour comprendre la création, à ce moment-là, des mythes qui donneraient soutien et orientation au projet d'affirmation du prestige politique du roi et à la consolidation de sa domination sur la région et sur tout le territoire brésilien. on analysera en particulier le conflit de mémoires entre la signification symbolique de la célébration et la révolte du peuple de Minas contre l'exploitation coloniale portugaise qui avait éclaté dans la région environ trois décennies avant.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Writing about philosophical practice with children requires a memory of the body, a body that holds on to what is important to itself. My memory begins with my contact with the ideas of Matthew Lipman and the new ideas brought by his words, and continues with the need to change some of them and assign different meanings to others. Since my reading of the thinkers of the so called “Frankfurt School,” some words have taken new meanings to me, and have informed the way I now understand the practice of philosophy with children and its relationship to issues like educational “formation,” as well as others. Philosophical practice is unique, and needs to be thought, felt, and experienced; it has its own time and involves the construction and transformation of subjectivity itself. As such, to search for words in philosophy means to chose those words that can help us make sense and give meaning of what we do and think, allowing us to work with our thinking and with its forms of expression, beyond its technical dimension. In this sense, the usual emphasis of philosophy in its more technical dimension leads to an impoverishment of formation as experience, for the latter, which is a fundamental dimension of our lives, is rendered secondary. This has implications for the relationship between adults and children. When they reduce philosophy to a study of the formal capacity of thinking, teachers put students in the condition of a minority, and therefore in some way also put themselves in such a condition. In this paper, the activity of writing - as a way of expressing thought - allows me to conduct a tour my own subjectivity, and to encounter the words that express the meanings that inform what I think and do about my practice with philosophical novels, and about the value of generating texts related to philosophical practice, formation and assessment.
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1792, Madri. After years of inactivity, the Spanish Inquisition is born again with the mission of containing the laic winds that blow from the revolutionary France. Inês Bilbatúa, a rich merchant’s daugther, is victim of the inquisitorial machinery which tortures and violates her, through one of their abetters, the Dominican monk Lorenzo. Before being arrested, the young lady had served as model for the painter Francisco of Goya, who had also portrayed the monk Lorenzo. The Aragonese painter’s figure serves as narrative conductor of a history that narrates the young Inês’ via crucis and, at the same time, it recreates the historical scenery of the Napoleonic invasion (1808), through a basic element, the painting. Our work intends to analyze the relationships among movie, painting and history present in “Goya’s ghosts” (2006), of the Czech director Milos Forman (1932) - whose script was adapted to a homonymous book in 2007 -, a movie that is based on the artistic production of Francisco of Goya y Lucientes (1746 -1828), official painter of Carlos’ IV (1788 -1808) court and the most lucid columnist of his time, that knew how to capture in his works the religious fanaticism, the populist fervour, the governor’s hypocrisy and the horror and the violence of the war.
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Traditional logic gates are rapidly reaching the limits of miniaturization. Overheating of these components is no longer negligible. A new physical approach to the machine was proposed by Prof. C S. Lent “Molecular Quantum cellular automata”. Indeed the quantum-dot cellular automata (QCA) approach offers an attractive alternative to diode or transistor devices. Th units encode binary information by two polarizations without corrent flow. The units for QCA theory are called QCA cells and can be realized in several way. Molecules can act as QCA cells at room temperature. In collaboration with STMicroelectronic, the group of Electrochemistry of Prof. Paolucci and the Nananotecnology laboratory from Lecce, we synthesized and studied with many techniques surface-active chiral bis-ferrocenes, conveniently designed in order to act as prototypical units for molecular computing devices. The chemistry of ferrocene has been studied thoroughly and found the opportunity to promote substitution reaction of a ferrocenyl alcohols with various nucleophiles without the aid of Lewis acid as catalysts. The only interaction between water and the two reagents is involve in the formation of a carbocation specie which is the true reactive species. We have generalized this concept to other benzyl alcohols which generating stabilized carbocations. Carbocation describe in Mayr’s scale were fondametal for our research. Finally, we used these alcohols to alkylate in enantioselective way aldehydes via organocatalysis.
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The aim of this thesis was to investigate the synthesis of enantiomerically enriched heterocycles and dehydro-β-amino acid derivatives which can be used as scaffolds or intermediates of biologically active compounds, in particular as novel αvβ3 and α5β1 integrin ligands. The starting materials of all the compounds here synthesized are alkylideneacetoacetates. Alkylidene derivates are very usefull compounds, they are usually used as unsaturated electrophiles and they have the advantage of introducing different kind of functionality that may be further elaborated. In chapter 1, regio- and stereoselective allylic amination of pure carbonates is presented. The reaction proceeds via uncatalyzed or palladium-catalyzed conditions and affords enantiopure dehydro-β-amino esters that are useful precursor of biologically active compounds. Chapter 2 illustrates the synthesis of substituted isoxazolidines and isoxazolines via Michael addition followed by intramolecular hemiketalisation. The investigation on the effect of the Lewis acid catalysis on the regioselectivity of the addition it also reported. Isoxazolidines and isoxazolines are interesting heterocyclic compounds that may be regarded as unusual constrained -amino acids or as furanose mimetics. The synthesis of unusual cyclic amino acids precursors, that may be envisaged as proline analogues, as scaffolds for the design of bioactive peptidomimetics is presented in chapter 3. The synthesis of 2-substituted-3,4-dehydropyrrole derivatives starting from allylic carbonates via a two step allylic amination/ring closing metathesis (RCM) protocol is carried out. The reaction was optimized by testing different Grubbs’ catalysts and carbamate nitrogen protecting groups. Moreover, in view of a future application of these dehydro-β-amino acids as central core of peptidomimetics , the malonate chain was also used to protect nitrogen prior to RCM. Finally, chapter 4 presents the synthesis of two novel different classes of integrin antagonists, one derived from dehydro-β-amino acid prepared as described in chapter 1 and the other one has isoxazolidines synthesized in chapter 2 as rigid constrained core. Since that these compounds are promising RGD mimetics for αvβ3 and α5β1 integrins, they have been submitted to biological assay. and to interpret on a molecular basis their different affinities for the αvβ3 receptor, docking studies were performed using Glide program.
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Bei den schweren Tetrylenen [ERR’, E = Si—Pb; R, R’ = Organyl-, elementorganischer Rest] zeigt sich ein Lewis-amphoterer Charakter, der bei den silylsubstituierten besonders ausgeprägt ist, wodurch sie wertvolle Vorstufen für Folgereaktionen darstellen. Bis zur Fertigstellung der Arbeit waren von den schwersten Vertretern lediglich vier homoleptische silylsubstituierte Stannylene/Distannene und zwei Plumbylene bekannt und strukturell charakterisiert. Im Rahmen dieser Arbeit wurden nun zwei weitere homoleptische silylsubstituierte Stannylene und zwei Plumbylene charakterisiert [E{Si(SiMe3)2SiMe2t-Bu}2, E{Si(SiMe3)2Sii-Pr3}2, E =Sn, Pb]. Diese Stannylene und Sn[Si(SiMe3)3]2 reagieren mit AlH3NMe3 beziehungsweise LiAlH4 in einer α-Addition. Geht man zu dem sterisch weniger anspruchsvollen Silylsubstituenten Si(SiMe3)2Et über, so lassen sich ein neues Kaliumplumbanid und das bislang erste stabile einkernige Blei(III)-Radikal Pb[Si(SiMe3)2Et]3 synthetisieren. Analog lassen sich E[Si(SiMe3)3]3 [E = Sn, Pb] darstellen, von denen bislang nur die Zinnverbindung isoliert werden konnte. Pb[Si(SiMe3)3]2 reagiert mit Lewis-Basen [THF, NH3, KN(SiMe3)2, „KI"] zu den entsprechenden Addukten. Darüberhinaus wurden zwei Aluminiumsilylverbindungen [AlH2[Si(SiMe3)2SiMe2t-Bu]NMe3, LiAlH3[Si(SiMe3)3]] und die bislang ersten röntgenographisch charakterisierten tetrasilylsubstituierten Plumbane [Pb[Si(SiMe3)2Et]3R, R = SiMe3, Si(SiMe3)2Et] isoliert.
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Las reglas monásticas visigodas constituyen un corpus documental de importancia fundamental para el estudio del monacato primitivo en Hispania. Ellas reflejan, entre otros aspectos, la preocupación por los ideales de vida de su época, heredados en parte de diversos tratados clásicos, que expresaban, desde aspectos más profundos vinculados a la moral, hasta reglas más precisas relacionadas con el modo de comportamiento en sociedad. En la temprana Edad Media, esta preocupación fue retomada por las comunidades monásticas, rescatando elementos propios de las costumbres latinas tradicionales. En dicho contexto, este estudio se propone analizar la presencia de vestigios de latinidad clásica en las reglas monacales visigodas, las cuales sirvieron como receptáculo de aquellas tradiciones destinadas a regular los distintos aspectos de la vida del monje.
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The loss of water in a desiccating atmosphere (c.40% r.h. at 10°C) and uptake of water from a saturated atmosphere (100% r.h. at 10°C) was recorded at intervals over periods of many hours or days in the dominant mosses and macroiichens occurring near the Australian Casey Station. Wilkes Land, continental Antarctica. While major differences exist in the water holding capacity and rates of water loss between mosses and lichens, the minimum levels attained after prolonged exposure to desiccating conditions are remarkably similar. By contrast, the volume of water absorbed from a saturated atmosphere is very similar in both groups of cryptogams. Morphological and anatomical characters are responsible for many of the differences, both between species, and within species exhibiting different growth features. Thus, significantly larger amounts of water are held by colonies of Bryum algens with a dense tomentum of rhizoids than those with sparse rhizoids; similarly, the rhizinate Umbilicaria aprina held a greater volume of water than the erhizinate U. decussata. The filamentous mat form of Alectoria mimiscula permits a much higher water content to be attained than in the coarser fruticose forms of Usnea sphacelata and U. antarctica. The dense shoot arrangement in Schistidium antarcticum accounts for the high water holding capacity in the hydric turf form whereas the less densely packed shoots and thicker cell walls of the xeric cushion form maintain a lower water content. The rate of water loss (as percentage dry weight) was much faster in the turf form of Schistidium and tomenlose form of Bryum, although this trend was reversed when expressed as percentage of the initial water content. Minimal water contents arc achieved by the lichens in desiccating conditions within 6-12 hours, whereas the mosses take several times longer. The water relations characteristics of these cryptogams are considered in the light of their distribution in the field and of their metabolic activity under prevailing Antarctic conditions.