Raman Spectroscopy and DFT calculations for the Electronic Structure Characterization of Conjugated Polymers

Flash presentationIn the last three decades, there has been a broad academic and industrial interest in conjugated polymers as semiconducting materials for organic electronics. Their applications in polymer light-emitting diodes (PLEDs), polymer solar cells (PSCs), and organic field-effect transistors (OFETs) offer opportunities for the resolution of energy issues as well as the development of display and information technologies1. Conjugated polymers provide several advantages including low cost, light weight, good flexibility, as well as solubility which make them readily processed and easily printed, removing the conventional photolithography for patterning2. A large library of polymer semiconductors have been synthesized and investigated with different building blocks, such as acenes or thiophene and derivatives, which have been employed to design new materials according to individual demands for specific applications. To design ideal conjugated polymers for specific applications, some general principles should be taken into account, including (i) side chains (ii) molecular weights, (iii) band gap and HOMO and LUMO energy levels, and (iv) suited morphology.3-6 The aim of this study is to elucidate the impact that substitution exerts on the molecular and electronic structure of π-conjugated polymers with outstanding performances in organic electronic devices. Different configurations of the π-conjugated backbones are analyzed: (i) donor-acceptor configuration, (ii) 1D lineal or 2D branched conjugated backbones, and (iii) encapsulated polymers (see Figure 1). Our combined vibrational spectroscopy and DFT study shows that small changes in the substitution pattern and in the molecular configuration have a strong impact on the electronic characteristics of these polymers. We hope this study can advance useful structure-property relationships of conjugated polymers and guide the design of new materials for organic electronic applications.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A Cholinergic Synaptically Triggered Event Participates in the Generation of Persistent Activity Necessary for Eye Fixation

An exciting topic regarding integrative properties of the nervous system is how transient motor commands or brief sensory stimuli are able to evoke persistent neuronal changes, mainly as a sustained, tonic action potential firing. A persisting firing seems to be necessary for postural maintenance after a previous movement. We have studied in vitro and in vivo the generation of the persistent neuronal activity responsible for eye fixation after spontaneous eye movements. Rat sagittal brainstem slices were used for the intracellular recording of prepositus hypoglossi (PH) neurons and their synaptic activation from nearby paramedian pontine reticular formation (PPRF) neurons. Single electrical pulses applied to the PPRF showed a monosynaptic glutamatergic projection on PH neurons, acting on AMPA-kainate receptors. Train stimulation of the PPRF area evoked a sustained depolarization of PH neurons exceeding (by hundreds of milliseconds) stimulus duration. Both duration and amplitude of this sustained depolarization were linearly related to train frequency. The train-evoked sustained depolarization was the result of interaction between glutamatergic excitatory burst neurons and cholinergic mesopontine reticular fibers projecting onto PH neurons, because it was prevented by slice superfusion with cholinergic antagonists and mimicked by cholinergic agonists. As expected, microinjections of cholinergic antagonists in the PH nucleus of alert behaving cats evoked a gaze-holding deficit consisting of a re-centering drift of the eye after each saccade. These findings suggest that a slow, cholinergic, synaptically triggered event participates in the generation of persistent activity characteristic of PH neurons carrying eye position signals.Unión Europea Grants BI04-CT98-0546España, Ministerio de Ciencia PB98-0011, BFI2000-00936, BFI2000-1190, y BFI2002-0137

Random Generation of Arbitrary Waveforms for Emulating Three-Phase Systems

This paper describes an apparatus for generating a signal representative of steady-state and transient disturbances in three-phase waveforms of an ac electrical system as described in IEEE Std 1159-09. It can be configured as a synthesizer of randomly distorted signals for different applications: for testing the effects of disturbed grid on equipment and to generate patterns of electrical disturbances for the training of artificial neural networks, which are used for measuring power quality tasks. For the first purpose, voltage and current amplifiers are added in the output stage, which allows the generation of disturbed signals at grid level.Comisión Interministerial de Ciencia y Tecnología DPI2006-15467-C02-01Comisión Interministerial de Ciencia y Tecnología DPI2006-15467-C02-0

Nutrition Therapy in Critically Ill Patients with Liver Disease: A Narrative Review

Nutrition therapy in critically ill patients with liver disease represents a challenge for Intensive Care Units (ICUs). Nutritional status is correlated with the degree of hepatic dysfunction and the presence of malnutrition worsens outcomes in these patients. The nutritional risk that critically ill patients represent, together with the pathophysiological alterations of liver disease, especially in terms of nutrition intake and protein depletion, leads to malnutrition and sarcopenia. Nutrition therapy improves the survival of these patients; however, this is challenging since they more frequently experience difficulties with nutrition delivery. In consequence, both evaluation of nutritional status and an individualized approach seem mandatory for achieving nutrition objectives. The present narrative review discusses the importance of nutrition therapy, the recommendations of contemporary clinical practice guidelines, and a practical approach to provide the best possible nutrition therapy in patients with liver disease admitted to ICUs

Transferencia Competitiva en uniones a-a y a-b de oligotiofenos precursores de Modelos Dendriméricos

Los politiofenos ramificados tridimensionales (3D) y oligotiofenos dendriméricos han sido recientemente desarrollados en la búsqueda de mejoras en los materiales para aplicaciones fotovoltaicas (por ejemplo, un mayor área de contacto entre dador y aceptor, absorciones moduladas hacia el visible-NIR, etc)[1-2]. Este trabajo trata de elucidar el efecto “competitivo” que presentan la conjugación en posición α-β sobre la de tipo α-α[3], mediante la caracterización de estados excitados y de diferente carga de tres oligotiofenos ramificados (ver Figura 1)[4-5], evaluando mecanismos de vital importancia para optimizar el funcionamiento en células solares. Este estudio se lleva a cabo mediante una amplia variedad de técnicas (como espectroscopías de absorción, emisión y de estados de transición triplete, así como espectroelectroquímica) en combinación con cálculos en DFT, y comparando dichos resultados con los de sus homólogos α-lineales. De este modo se podrá indicar la contribución de la conjugación α-β respecto de la α-α en la deslocalización de cargas en diferentes estados de oxidación y en estados electrónicos singlete y triplete[6].Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Effect of the TiO2-carbon interface on charge transfer and ethanol photo-reforming

Carbonaceous materials have been widely used in photocatalysis to solve the drawback of rapid electron-hole recombination rate of semiconductors such as titania. To further understand the charge separation mechanism and its effect on the ethanol photoreforming hydrogen production, two types of carbon-titania hybrid material systems were studied. One of them is multi-walled carbon nanotube-titania nanoparticles (MWCNT-TiO2) prepared by a sol-gel synthesis method, which according to previous studies should facilitate the migration of electrons from TiO2 to MWCNT. The second system is based on a two-dimensional carbon (exfoliated carbon, 2DC) and titania nanosheet (TNS), synthesized through a hydrothermal route that enabled the formation of strong interaction between the carbon and the {001} facets of the TNS. Our results demonstrate that this unique design promotes the migration of the photogenerated holes from the TNS to the expanded carbon. Steady state photoluminescence studies indicate that the recombination rate in both cases decreases benefiting from the spatial separation of photogenerated carriers, resulting in enhanced photocatalytic activity. The present study provides a comprehensive understanding of the charge separation mechanism and its effect on ethanol photoreforming hydrogen production in carbon-titania hybrid material systems and clearly highlights the need for further research to investigate the charge transfer in these kinds of hybrid materials

Propuesta de anteproyecto arquitectónico del Albergue Álvaro Sequeira para personas sin hogar en el distrito VII de la ciudad de Managua.

La investigación expone una propuesta de anteproyecto arquitectónico de un Albergue para personas sin hogar en el distrito VII de la ciudad de Managua, el desarrollo de este tema surge gracias a la idea de brindar un espacio para que a estas personas puedan vivir y reinsertarlos a la sociedad, ya que actualmente nuestra ciudad no cuenta con edificios de este tipo. El estudio aborda aspectos importantes a cómo son las normativas y criterios para el diseño, el análisis de modelos de edificios similares al proyecto, y como parte final de propuesta de diseño del Albergue Álvaro Sequeira

Carbazole-based Diradicals for Dynamic Covalent Chemistry

Dynamic covalent chemistry (DCC) is focused on the creation of structural scaffolds based on chemical components that interact through strong but reversible bonds. In fact, dynamic covalent bonds receive lot of attention because of their unique feature to become reversible under mild conditions.1 conjugated diradical compounds has emerged as essential building blocks in DCC.2 In this work, we will review our most recent works on the formation of stimuli-responsive cyclophanes by self-assembly of carbazole-based diradicals. To this end, we use a combined experimental and theoretical approach that links vibrational spectroscopy with DFT calculations. In this sense, it is interesting to note that we have recently demonstrated the potential of a para-substituted carbazole with terminal dicyanomethylene (DCM) groups to act as building blocks in DCC.3 This quinoid carbazole monomer transforms to a macrocycle cyclophane upon soft external stimuli (temperature, pressure, light), showing strong chromic features. In addition, we have also recently explored how the different DCM substitution position affects the interesting chromoactive properties of carbazole compounds.4 Finally, we are currently exploring the effect of the elongation of the carbazole backbone on the formation of stimuli-responsive cyclophanes.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Severity of post-cardiac surgery acute kidney injury and long-term mortality: is chronic kidney disease the missing link?

While the retrospective cohort study by Lopez-Delgado and colleagues suggests a strong association of the RIFLE classification and long-term mortality of acute kidney injury (AKI) after post-cardiac surgery, it has a number of limitations. The numbers of patients with pre-existing chronic kidney disease (CKD) or with non-recovery of renal function, de novo CKD or progression of CKD to stage V are not given. The authors used an obsolete definition of CKD and a modified RIFLE classification system for definition and grading of AKI. Taken together, numerous studies underscore the strong association between AKI and de novo CKD. Severity, duration and frequency of AKI as well as age, comorbidities and pre-existing CKD are known risk factors for the development and/or progression of CKD. Careful analyses of the cumulative mortality curves reported by Lopez-Delgado and colleagues or by our group revealed a triphasic pattern. In the early phase, survival rates drop steeply due to critical illness, followed by a phase of smaller decline (caused by patient characteristics and development of CKD) and later on by a flatter survival curve attributable to the high cardiovascular mortality of progressive CKD. Physicians need to consider the long-term sequels of severe AKI. Lopez Delgado and colleagues's study provides further arguments for an early follow-up of survivors of AKI by nephrologists

Response by Caravaca Pérez et al to Letter Regarding Article, "Potential Role of Natriuretic Response to Furosemide Stress Test During Acute Heart Failure".

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