Nanostructures for Surface Plasmon enhanced light emission

L’emissió espontània juga un paper important a dispositius com els LEDs o els làsers. És important saber manipular l’emissió espontània per tal de millorar el funcionament d’aquests dispositius. Podem manipular-la de dues formes diferents: augmentant-la o inhibint-la. Per exemple, augmentar l’emissió espontània a la cavitat d’un làser en la direcció de la cavitat permet disminuir el llindar, quan el làser passa d’emissió espontània a emissió estimulada. Una de les aplicacions més populars de la manipulació de l’emissió espontània és l’augment de l’emissió als LEDs. Es pot manipular l’emissió espontània de diverses maneres com amb l’ús de microcavitats o amb polaritons plasmònics superficials. Aquest darrer mètode és el que es farà servir

Propuesta de criterios de evaluación y alertas para el análisis del desempeño energético de viviendas a partir del Índice de Prestaciones Energéticas (IPE)

En este trabajo se describe la propuesta de criterios de evaluación y alertas para el análisis del desempeño energético de una vivienda, la cual se implemento en la prueba piloto llevada a cabo para establecer la escala del índice de Prestaciones Energéticas (IPE), para la Ciudad Autónoma de Buenos Aires (CABA) en el marco del Programa Nacional de Etiquetado de Viviendas. El sistema de alerta se basó en los siguientes indicadores: nivel general de aislación, eficiencia de los equipos activos de calefacción, refrigeración y ACS y nivel de aprovechamiento de las ganancias solares en invierno y las pérdidas en verano del parque de viviendas relevadas. El objetivo del código de alertas propuesto es ayudar a los profesionales en la interpretación de la información generada. Tiene asociado un conjunto de recomendaciones preliminares en relación a los aspectos que el profesional debería revisar para analizar posibles mejoras tendientes a disminuir el valor del IPE. La metodología propuesta si bien fue aplicada en la CABA, puede extender su aplicación a distintas zonas del país, simplemente variando criterios y valores de corte en función del clima, normativas y praxis constructivas.This work describes the proposal of evaluation criteria and alerts for the analysis of the energy performance of a dwelling, which was implemented in the pilot test carried out to build the scale of the Energy Performance Index (IPE), for City Autónoma de Buenos Aires (CABA) within the framework of the Building Energy Labelling National Program. The alert system was based on the following indicators: general level of insulation, efficiency of active heating, cooling and DHW equipment and level of use of solar gains in winter and losses in summer of the dwelling park surveyed. The objective of the proposed alert code is to help professionals in the interpretation of the information generated. It is associated with a set of preliminary recommendations in relation to the aspects that the professional should review to analyze possible improvements aimed at reducing the IPE value. Although the proposed methodology was applied in CABA, its application can be extended to different areas of the country, simply by varying criteria and cut-off values, depending on the climate, regulations and construction practices.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Charge disproportionation and the pressure-induced insulator?metal transition in cubic perovskite PbCrO3

The perovskite PbCrO3 is an antiferromagnetic insulator. However, the fundamental interactions leading to the insulating state in this single-valent perovskite are unclear. Moreover, the origin of the unprecedented volume drop observed at a modest pressure of P = 1.6 GPa remains an outstanding problem. We report a variety of in situ pressure measurements including electron transport properties, X-ray absorption spectrum, and crystal structure study by X-ray and neutron diffraction. These studies reveal key information leading to the elucidation of the physics behind the insulating state and the pressure-induced transition. We argue that a charge disproportionation 3Cr4+ → 2Cr3+ + Cr6+ in association with the 6s-p hybridization on the Pb2+ is responsible for the insulating ground state of PbCrO3 at ambient pressure and the charge disproportionation phase is suppressed under pressure to give rise to a metallic phase at high pressure. The model is well supported by density function theory plus the correlation energy U (DFT+U) calculations.Fil: Cheng, Jinguang. University Of Texas At Austin; Estados Unidos. Chinese Academy Of Sciences; República de China. University of Tokyo. Institute for Solid State Physics; JapónFil: Kweon, K. E.. University Of Texas At Austin; Estados UnidosFil: Larregola, Sebastian Alberto. University Of Texas At Austin; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Ding, Yang. Argonne National Laboratory; Estados UnidosFil: Shirako, Y.. University Of Texas At Austin; Estados UnidosFil: Marshall, L. G.. University Of Texas At Austin; Estados Unidos. Northeastern University; Estados UnidosFil: Li, Z. Y.. University Of Texas At Austin; Estados UnidosFil: Li, X.. University Of Texas At Austin; Estados UnidosFil: Dos Santos, António M.. Oak Ridge National Laboratory. Quantum Condensed Matter Division; Estados UnidosFil: Suchomel, M. R.. Argonne National Laboratory; Estados UnidosFil: Matsubayashi, K.. University of Tokyo. Institute for Solid State Physics; JapónFil: Uwatoko, Y.. University of Tokyo. Institute for Solid State Physics; JapónFil: Hwang, G. S.. University Of Texas At Austin; Estados UnidosFil: Goodenough, John B.. University Of Texas At Austin; Estados UnidosFil: Zhou, J. S.. University Of Texas At Austin; Estados Unido

A Photochromic Azobenzene Peptidomimetic of a β-Turn Model Peptide Structure as a Conformational Switch

The insertion of azobenzene moiety in complex molecular protein or peptide systems can lead to molecular switches to be used to determine kinetics of folding/unfolding properties of secondary structures, such as α-helix, β-turn, or β-hairpin. In fact, in azobenzene, absorption of light induces a reversible trans ↔ cis isomerization, which in turns generates a strain or a structure relaxation in the chain that causes peptide folding/unfolding. In particular azobenzene may permit reversible conformational control of hairpin formation. In the present work a synthetic photochromic azobenzene amino acid derivative was incorporated as a turn element to modify the synthetic peptide [Pro7,Asn8,Thr10]CSF114 previously designed to fold as a type I β-turn structure in biomimetic HFA/water solution. In particular, the P-N-H fragment at positions 7–9, involved in a β-hairpin, was replaced by an azobenzene amino acid derivative (synthesized ad hoc) to investigate if the electronic properties of the novel peptidomimetic analog could induce variations in the isomerization process. The absorption spectra of the azopeptidomimetic analog of the type I β-turn structure and of the azobenzene amino acid as control were measured as a function of the irradiation time exciting into the respective first ππ* and nπ* transition bands. Isomerization of the azopeptidomimetic results strongly favored by exciting into the ππ* transition. Moreover, conformational changes induced by the cis↔ trans azopeptidomimetic switch were investigated by NMR in different solvents

Développement de mimes de coude b inhibiteurs d'interaction protéine-protéine (une étude à l'interface entre chimie organique, chimie structurale et biochimie)

PARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF