Ultrafast charge transfer dynamics in supramolecular Pt(II) donor-bridge-acceptor assemblies: the effect of vibronic coupling

Thanks to major advances in laser technologies, recent investigations of the ultrafast coupling of nuclear and electronic degrees of freedom (vibronic coupling) have revealed that such coupling plays a crucial role in a wide range of photoinduced reactions in condensed phase supramolecular systems. This paper investigates several new donor–bridge–acceptor charge-transfer molecular assemblies built on a trans-Pt(II) acetylide core. We also investigate how targeted vibrational excitation with low-energy IR light post electronic excitation can perturb vibronic coupling and affect the efficiency of electron transfer (ET) in solution phase. We compare and contrast properties of a range of donor–bridge–acceptor Pt(II) trans-acetylide assemblies, where IR excitation of bridge vibrations during UV-initiated charge separation in some cases alters the yields of light-induced product states. We show that branching to multiple product states from a transition state with appropriate energetics is the most rigid condition for the type of vibronic control we demonstrate in our study

Tecnologies de la llengua i les seves aplicacions

[Resumo] A investigación en Lingüística Computacional e Procesamento da Lenguaje Natural deu lugar estes últimos anos ás denominadas Tecnoloxías da Linguaxe, cuxo obxectivo principal é o desenvolvemento de sistemas informáticos capaces de recoñeceren, comprenderen e xeraren linguaxe humana en todas as súas formas. Con esta finalidade, desenvolveuse unha serie de aplicacións, como a Tradución Automática, a Extracción e Recuperación da Información, a Clasificación de Documentos etc., que procesan a información para facilitaren o acceso, organización e transmisión do coñecemento que xera a chamada Sociedade da Información en que vivimos. Como noutras disciplinas científicas, na área da Lingüística Computacional e do Procesamento da Linguaxe Natural pasouse dunha etapa inicial centrada na investigación básica de carácter experimental a outra en que se interaxe máis coa sociedade e, por tanto, máis interesada na creación de produtos e aplicacións que resolvan problemas reais. Isto significa desenvolver sistemas e recursos capaces de analizaren a linguaxe sen restricións, isto é, que ofrezan unha ampla cobertura lingüística. Neste artigo preséntase de xeito introdutorio os recursos (lingüísticos) e as aplicacións máis características que se desenvolven actualmente no marco das Tecnoloxías da Linguaxe. En concreto, salientaremos dos recursos necesarios os analizadores e desambiguadores morfolóxicos e sintácticos, os lexicóns computacionais e os corpus lingüísticos, nomeadamente os etiquetados. Canto ás aplicacións, centrarémonos básicamente na Recuperación e Extracción da Información e na Tradución Automática.[Abstract] In the last years, research on Computational Linguistics and Natural Language Processing has led to Language Technologies, whose main goal is to develop computer systems capable to recognize, understand and generate human languages in all their forms. For this purpose, several applications have been developed, such as Machine Translation, Information Retrieval and Information Extraction or Document Classification. These applications process the language in order to ease access to knowledge, its organization or its transmission, activities needed by our Information Society. As in other disciplines, Computational Linguistics and Natural Language Processing have gone from a first period of basic, experimental research to another in which new products and real applications have to be created, in order to solve interaction problems. This means that we need to develop systems and resources capable to deal with unrestricted language, that is, broad-coverage systems and resources. This paper presents an introduction to linguistics resources as well as the main applications being developed nowadays in the Language Technologies framework. More concretely, it emphasizes morphological analyzers, taggers, syntactic parsers, computational lexicons and linguistic annotated corpora. As for applications, stress is laid on Information Retrieval, Information Extraction and Machine Translation

Text as Scene: Discourse Deixis and Bridging Relations

This paper presents a new framework, "text as scene", which lays the foundations for the annotation of two coreferential links: discourse deixis and bridging relations. The incorporation of what we call textual and contextual scenes provides more flexible annotation guidelines, broad type categories being clearly differentiated. Such a framework that is capable of dealing with discourse deixis and bridging relations from a common perspective aims at improving the poor reliability scores obtained by previous annotation schemes, which fail to capture the vague references inherent in both these links. The guidelines presented here complete the annotation scheme designed to enrich the Spanish CESS-ECE corpus with coreference information, thus building the CESS-Ancora corpus

Identifying electron transfer coordinates in Donor-Bridge-Acceptor systems using mode projection analysis

We report upon an analysis of the vibrational modes that couple and drive the state-to-state electronic transfer branching ratios in a model donor-bridge-acceptor system consisting of a phenothiazine-based donor linked to a naphthalene-monoimide acceptor via a platinum-acetylide bridging unit. Our analysis is based upon an iterative Lanczos search algorithm that finds superpositions of vibronic modes that optimize the electron/nuclear coupling using input from excited-state quantum chemical methods. Our results indicate that the electron transfer reaction coordinates between a triplet charge transfer state and lower lying chargeseparated and localised excitonic states are dominated by asymmetric and symmetric modes of the acetylene groups on either side of the central atom in this system. In particular, we find that while a nearly symmetric mode couples both the charge-separation and charge-recombination transitions more or less equally, the coupling along an asymmetric mode is far greater suggesting that IR excitation of the acetylene modes preferentially enhances charge recombination transition relative to charge-separation

Salvador Espriu: una proposta entre el racionalisme cartesià, la moral pràctica de Sèneca i la mística jueva

Summary: On the basis of a canon of readings recommended by Salvador Espriu himself, the 21st century reader is invited to participate in the poet’s creative process, which suggests an ethical line of social engagement that is mundane, rational and active and that is based on the conquest of the subject’s freedom. [Keywords: Subject, poetry, truth, dialectic, reason, self-analysis, organic-work, kabbala

Focus of negation: Its identification in Spanish

This article describes the criteria for identifying the focus of negation in Spanish. This work involved an in-depth linguistic analysis of the focus of negation through which we identified some 10 different types of criteria that account for a wide variety of constructions containing negation. These criteria account for all the cases that appear in the NewsCom corpus and were assessed in the annotation of this corpus. The NewsCom corpus consists of 2955 comments posted in response to 18 different news articles from online newspapers. The NewsCom corpus contains 2965 negative structures with their corresponding negation marker, scope, and focus. This is the first corpus annotated with focus in Spanish and it is freely available. It is a valuable resource that can be used both for the training and evaluation of systems that aim to automatically detect the scope and focus of negation and for the linguistic analysis of negation grounded in real data

DISCOver: DIStributional approach based on syntactic dependencies for discovering COnstructions

One of the goals in Cognitive Linguistics is the automatic identification and analysis of constructions, since they are fundamental linguistic units for understanding language. This article presents DISCOver, an unsupervised methodology for the automatic discovery of lexico-syntactic patterns that can be considered as candidates for constructions. This methodology follows a distributional semantic approach. Concretely, it is based on our proposed pattern-construction hypothesis: those contexts that are relevant to the definition of a cluster of semantically related words tend to be (part of) lexico-syntactic constructions. Our proposal uses Distributional Semantic Models for modelling the context taking into account syntactic dependencies. After a clustering process, we linked all those clusters with strong relationships and we use them as a source of information for deriving lexico-syntactic patterns, obtaining a total number of 220,732 candidates from a 100 million token corpus of Spanish. We evaluated the patterns obtained intrinsically, applying statistical association measures and they were also evaluated qualitatively by experts. Our results were superior to the baseline in both quality and quantity in all cases. While our experiments have been carried out using a Spanish corpus, this methodology is language independent and only requires a large corpus annotated with the parts of speech and dependencies to be applied

Tratamiento de la hipertensión arterial en la menopausia

Introducción: la hipertensión arterial en la menopausia está influencia por el descenso de estrógenos que induce disfunción endotelial y aumento del índice de masa corporal. Objetivos: describir los mecanismos fisiopatológicos de la hipertensión arterial en la menopausia y los antihipertensivos recomendados en la actualidad. Metodología: se realizó una revisión bibliográfica en las bases de datos PubMed y SciELO utilizando las palabras claves: hipertensión arterial y menopausia. Resultados: no existen diferencias en la respuesta a los diferentes antihipertensivos y ambos sexos se benefician en la reducción de la morbimortalidad cardiovascular con la disminución de la presión arterial. La efectividad preventiva de complicaciones cardiovasculares con los antihipertensivos no difiere según el sexo y por lo tanto la elección del medicamento no puede basarse en este criterio en mujeres menopáusicas. Conclusión: la deficiencia de estrógeno induce disfunción endotelial y aumento del índice de masa corporal siendo las principales causas de hipertensión en la menopausia. Todos los antihipertensivos están recomendados en la menopausia

(13)C or Not (13)C: Selective Synthesis of Asymmetric Carbon-13-Labeled Platinum(II) cis-Acetylides.

Asymmetric isotopic labeling of parallel and identical electron- or energy-transfer pathways in symmetrical molecular assemblies is an extremely challenging task owing to the inherent lack of isotopic selectivity in conventional synthetic methods. Yet, it would be a highly valuable tool in the study and control of complex light-matter interactions in molecular systems by exclusively and nonintrusively labeling one of otherwise identical reaction pathways, potentially directing charge and energy transport along a chosen path. Here we describe the first selective synthetic route to asymmetrically labeled organometallic compounds, on the example of charge-transfer platinum(II) cis-acetylide complexes. We demonstrate the selective (13)C labeling of one of two acetylide groups. We further show that such isotopic labeling successfully decouples the two ν(C≡C) in the mid-IR region, permitting independent spectroscopic monitoring of two otherwise identical electron-transfer pathways, along the (12)C≡(12)C and (13)C≡(13)C coordinates. Quantum-mechanical mixing leads to intriguing complex features in the vibrational spectra of such species, which we successfully model by full-dimensional anharmonically corrected DFT calculations, despite the large size of these systems. The synthetic route developed and demonstrated herein should lead to a great diversity of asymmetric organometallic complexes inaccessible otherwise, opening up a plethora of opportunities to advance the fundamental understanding and control of light-matter interactions in molecular systems

Negation in Spanish: analysis and typology of negation patterns

En este artículo se presentan los criterios aplicados para la anotación del corpus SFU ReviewSP-NEGcon negación y la tipología lingüística correspondiente. Esta tipología presenta la ventaja de ser fácilmente expresable en términos de un tagset para la anotación de corpus, de presentar tipos claramente delimitados, evitando así la ambigüedad en el proceso de anotación, y de presentar una amplia cobertura, es decir, que ha servido para resolver todos los casos que han aparecido. El corpus contiene 400 comentarios y 198.551 palabras. Actualmente está anotado en un 75% y, de un total de 6.331 oraciones revisadas, se han identificado 2.953 estructuras de negación.In this paper we present the criteria applied for the annotation of the SFU ReviewSP-NEGcorpus and the corresponding linguistic typology. This typology has the advantage that it is easy to express in terms of a tagset for corpus annotation: the types are clearly defined, which avoid the ambiguity in the annotation process, and they present a wide coverage (i.e. they covered/solved all the cases occurring in the corpus). The corpus consists of 400 reviews and 198,551 words. Currently, we have annotated 75% and from a total of 6,331 annotated sentences 2,953 contain at least one negation.Financiado por fondos FEDER, los proyectos: TIN2015-65136-C2-1-R y TIN2015-71147-C2-2 del MINECO y FPU014/00983 del MECD