69 resultados para reductive paraphrase

em QUB Research Portal - Research Directory and Institutional Repository for Queen's University Belfast


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Starting from the premise that human communication is predicated on translational phenomena, this paper applies theoretical insights and practical findings from Translation Studies to a critique of Natural Semantic Metalanguage (NSM), a theory of semantic analysis developed by Anna Wierzbicka. Key tenets of NSM, i.e. (1) culture-specificity of complex concepts; (2) the existence of a small set of universal semantic primes; and (3) definition by reductive paraphrase, are discussed critically with reference to the notions of untranslatability, equivalence, and intra-lingual translation, respectively. It is argued that a broad spectrum of research and theoretical reflection in Translation Studies may successfully feed into the study of cognition, meaning, language, and communication. The interdisciplinary exchange between Translation Studies and linguistics may be properly balanced, with the former not only being informed by but also informing and interrogating the latter.

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Reductive cyclisation of ail E-vinyl bromide with ail allylic acetate proceeds under palladium catalysis 10 give the 8-dehydropumiliotoxin skeleton, a potential advanced precursor to 8-deoxypumiliotoxin alkaloids. Control of the stereochemistry of the E-vinyl bromide precursor is achieved readily using the Kogen or Bruckner bromophosphonate reagents and the reductive cyclisation proceeds with retention of the vinyl bromide stereochemistry. The mechanism for the cyclisation involves an in situ conversion of the allylic acetate to ail allyl stannane followed by ail intramolecular Stille-type coupling.

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The kinetics of reductive dissolution of NaBiO3, by Mn-II and Ce-III ions are studied as a function of [Mn-II] or [Ce-III], [Bi-III], [H+] and temperature. They fit a simple inverse-cubic rate law and can be readily interpreted using a mechanism in which the rate-determining step is the reaction between an adsorbed reducing species (i.e. a Mn-II or Ce-III ion) and its associated surface site; protonation of the surface site promotes the rate of reaction. The rate of dissolution decreases with increasing initial concentration of Bi-III ions owing to competitive inhibition by the latter species. A kinetic model, based on this mechanism, is applied and provides a quantitative description of the observed kinetics.

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This paper describes the ParaPhrase project, a new 3-year targeted research project funded under EU Framework 7 Objective 3.4 (Computer Systems), starting in October 2011. ParaPhrase aims to follow a new approach to introducing parallelism using advanced refactoring techniques coupled with high-level parallel design patterns. The refactoring approach will use these design patterns to restructure programs defined as networks of software components into other forms that are more suited to parallel execution. The programmer will be aided by high-level cost information that will be integrated into the refactoring tools. The implementation of these patterns will then use a well-understood algorithmic skeleton approach to achieve good parallelism. A key ParaPhrase design goal is that parallel components are intended to match heterogeneous architectures, defined in terms of CPU/GPU combinations, for example. In order to achieve this, the ParaPhrase approach will map components at link time to the available hardware, and will then re-map them during program execution, taking account of multiple applications, changes in hardware resource availability, the desire to reduce communication costs etc. In this way, we aim to develop a new approach to programming that will be able to produce software that can adapt to dynamic changes in the system environment. Moreover, by using a strong component basis for parallelism, we can achieve potentially significant gains in terms of reducing sharing at a high level of abstraction, and so in reducing or even eliminating the costs that are usually associated with cache management, locking, and synchronisation. © 2013 Springer-Verlag Berlin Heidelberg.

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Herein, we present a facile method for the formation of monodispersed metal nanoparticles (NPs) at room temperature from M(III)Cl3 (with M = Au, Ru, Mn, Fe or V) in different media based on N,N-dimethylformamide (DMF) or water solutions containing a protic ionic liquid (PIL), namely the octylammonium formate (denoted OAF) or the bis(2-ethyl-hexyl)ammonium formate (denoted BEHAF). These two PILs present different structures and redox-active structuring properties that influence their interactions with selected molecular compounds (DMF or water), as well as the shape and the size of formed metal NPs in these solutions. Herein, the physical properties, such as the thermal, transport and micellar properties, of investigated PIL solutions were firstly investigated in order to understand the relation between PILs structure and their properties in solutions with DMF or water. The formation of metal NPs in these solutions was then characterized by using UV–vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and dynamic light scattering (DLS) measurements. From our investigations, it appears that the PILs structure and their aggregation pathways in selected solvents affect strongly the formation, growths, the shape and the size of metal NPs. In fact by using this approach, the shape-/size-controlled metal NPs can be generated under mild condition. This approach suggests also a wealth of potential for these designer nanomaterials within the biomedical, materials, and catalysis communities by using designer and safer media based on PILs.

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Herein, a facile method was developed for preparing high concentration of monodispersed gold nanoparticles (NPs) at room temperature from gold(III) chloride by using different media based on N,N-dimethylformamide or water solutions containing a protic ionic liquid (PIL), namely, the octylammonium formate or the bis(2-ethyl-hexyl)ammonium formate, based on which both PILs were used as redox-active structuring media. The formation of gold NPs in these systems was then characterized using UV-visible spectroscopy, transmission electron microscopy, and dynamic light scattering. From these investigations, it appears that the structure and aggregation pathway of PILs in selected solvents affect strongly the formation, growth, the shape, and the size of gold NPs. In fact, by using this approach, the shape-/ size-controlled gold NPs (branched and spherical) can be generated under mild condition. This approach suggests also a wealth of potential for these designer nanomaterials within the biomedical, materials, and catalysis communities by using designer and safer media based on PILs.

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Semiconductor-sensitised photocatalysis is a well-established and growing area of research, innovation and commercialisation; the latter being mostly limited to the use of TiO2 as the semiconductor. Most of the work on semiconductor photocatalytic systems uses oxygen as the electron acceptor and explores a wide range of electron donors; such systems can be considered to be examples of oxidative photocatalysis, OP. OP underpins most current examples of commercial self-cleaning materials, such as: glass, tiles, concrete, paint and fabrics. OP, and its myriad of applications, have been reviewed extensively over the years both in this journal and elsewhere. However, the ability of TiO2, and other semiconductor sensitisers, to promote reductive photocatalysis, RP, especially of dyes, is significant and, although less well-known, is of growing importance. In such systems, the source of the electrons is some easily oxidised species, such as glycerol. One recent, significant example of a RP process is with respect to photocatalyst activity indicator inks. paiis, which provide a measure of the activity of a photocatalytic film under test via the rate of change of colour of the dye in the ink coating due to irreversible RP. In contrast, by incorporating the semiconductor sensitiser in the ink, rather than outside it, it is possible to create an effective UV dosimeter, based on RP, which can be used as a sun-burn warning indicator. In the above examples the dye is reduced irreversibly, but when the photocatalyst in an ink is used to reversibly photoreduce a dye, a novel, colourimetric oxygen-sensitive indicator ink can be created, which has commercial potential in the food packaging industry. Finally, if no dye is present in the ink, and the semiconductor photocatalyst-loaded ink film coats an easily reduced substrate, such as a metal oxide film, then it can be used to reduce the latter and so, for example, clean up tarnished steel. The above are examples of smart inks, i.e. inks that are active and provide either dynamic information (such as UV dose or O2 level) or a useful function (such as tarnish removal), and all work via a RP process and are reviewed here

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Alasdair MacIntyre condemns modern politics, specifically liberalism and the institutions of the liberal state, as irredeemably fallen. His core argument is that the liberal state encourages a disempowering ‘compartmentalization’ of people’s everyday roles and activities that undermines the intersubjective conditions of human flourishing. MacIntyre’s alternative is an Aristotelian politics centred on the notion of “practice.” Defined by justice and solidarity, this politics can only be realized, he claims, within local communities which oppose and resist the dictates of the administrative state and capitalist market. Here it is argued that MacIntyre’s notion of “practice” represents a compelling ethical-political ideal. However, the belief that this ideal is best realized within local communities is rejected. In privileging local community, MacIntyre relies on a reductive view of modern states and overlooks the institutional conditions of a just polity. Against this, it is argued that a politics of human flourishing cannot succeed without an emancipatory transformation of large-scale, trans-communal institutions, in particular the state.

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A previously unreported alcohol dehydrogenase enzyme in the mutant soil bacterium Pseudomonas putida UV4 catalyses the reduction of 2-, 3- and 4-acylpyridines to afford the corresponding (S)-1-pyridyl alkanols, with moderate to high e.e., whilst under the same conditions 2,6-diacetylpyridine is readily converted to the corresponding enantiopure C2-symmetric (S,S)-diol in one step. In contrast, the toluene dioxygenase enzyme in the same organism catalyses the hydroxylation of 2- and 3-alkylpyridines to (R)-1-(2-pyridyl) and (R)-1-(3-pyridyl)alkanols. This combination of oxidative and reductive biotransformations thus provides a method for preparing both enantiomers of chiral 1-pyridyl alkanols using one biocatalyst.

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The propagation of acoustic nonlinear excitations in an electron-positron-ion (e-p-i) plasma composed of warm electrons and positrons, as well as hot ions, has been investigated by adopting a two-dimensional cylindrical geometry. The electrons and positrons are modeled by hydrodynamic fluid equations, while the ions are assumed to follow a temperature-parametrized Boltzmann distribution (the fixed ion model is recovered in the appropriate limit). This situation applies in the accretion disk near a black hole in active galactic nuclei, where the ion temperature may be as high as 3 to 300 times that of the electrons. Using a reductive perturbation technique, a cylindrical Kadomtsev-Petviashvili equation is derived and its exact soliton solutions are presented. Furthermore, real situations in which the strength of the nonlinearity may be weak are considered, so that higher-order nonlinearity plays an important role. Accordingly, an extended cylindrical Kadomtsev-Petviashvili equation is derived, which admits both soliton and double-layer solutions. The characteristics of the nonlinear excitations obtained are investigated in detail

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The nonlinear properties of two-dimensional cylindrical quantum dust-ion-acoustic (QDIA) and quantum dust-acoustic (QDA) waves are studied in a collisionless, unmagnetized and dense (quantum) dusty plasma. For this purpose, the reductive perturbation technique is employed to the quantum hydrodynamical equations and the Poisson equation, obtaining the cylindrical Kadomtsev–Petviashvili (CKP) equations. The effects of quantum diffraction, as well as quantum statistical and geometric effects on the profiles of QDIA and QDA solitary waves are examined. It is found that the amplitudes and widths of the nonplanar QDIA and QDA waves are significantly affected by the quantum electron tunneling effect. The addition of a dust component to a quantum plasma is seen to affect the propagation characteristics of localized QDIA excitations. In the case of low-frequency QDA waves, this effect is even stronger, since the actual form of the potential solitary waves, in fact, depends on the dust charge polarity (positive/negative) itself (allowing for positive/negative potential forms, respectively). The relevance of the present investigation to metallic nanostructures is highlighted.

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Using cyclic voltammetry, the electrochemical reduction of benzoic acid (BZA) has been studied at Pt and Au microelectrodes (10 and 2 mu m diameter) in six room temperature ionic liquids (RTILs), namely [C(2)mim][NTf2], [C(4)mim][NTf2], [C(4)mpyrr][NTf2], [C(4)mim][BF4], [C(4)mim][NO3], and [C(4)mim][PF6] (where [C(n)mim](+) = 1-alkyl-3-methylimidazolium, [NTf2](-) = bis(trifluoromethylsulfonyl)imide, [C(4)mpyrr](+) = N-butyl-N-methylpyrrolidinium, [BF4](-) = tetrafluoroborate, [NO3](-) = nitrate, and [PF6](-) = hexafluorophosphate). In all cases, a main reduction peak was observed, assigned to the reduction of BZA in a CE mechanism, where dissociation of the acid takes place before electron transfer to the dissociated proton. One anodic peak was observed on the reverse sweep, assigned to the oxidation of adsorbed hydrogen, and a reductive

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The electrochemical reduction of I atm hydrogen sulfide gas (H2S) has been studied at a platinum microelectrode (10 mu m diameter) in five room temperature ionic liquids (RTILs): [C(2)mim][NTf2], [C(4)mpyrr][NTf2], [C(4)mim][OTf], [C(4)mim][NO3] and [C(4)mim]][PF6] (where [C(n)mim](+) = 1-alkyl-3-methylimidazolium, [NTf2](-) = bis(trifluoromethylsulfonyl)imide, [C(4)mpyrr](+) = N-butyl-N-methylpyrrolidinium, [OTf](-) = trifluoromethlysulfonate, [NO3](-) = nitrate, and [PF6](-) = hexafluorophosphate). In all five RTILs, a chemically irreversible reduction peak was observed on the reductive sweep, followed by one or two oxidative peaks on the reverse scan. The oxidation peaks were assigned to the oxidation of SH- and adsorbed hydrogen. In addition, a small reductive peak was observed prior to the large wave in [C(2)mim]][NTf2] only, which may be due to the reduction of a sulfur impurity in the gas. Potential-step chronoamperometry was carried out on the reduction peak of H2S, revealing diffusion coefficients of 3.2, 4.6, 2.4, 2.7, and 3.1 x 10(-11) m(2) s(-1) and solubilities of 529, 236, 537, 438, and 230 mM in [C(2)mim][NTf2], [C(4)mpyrr][NTf2], [C(4)mim][OTf], [C(4)mim][NO3], and [C(4)mim]][PF6], respectively. The solubilities of H2S in RTILs are much higher than those reported in conventional molecular solvents, suggesting that RTILs may be very favorable gas sensing media for H2S detection.