Integrated nano-plasmonics: reflecting a waveguide mode with a single nano-antenna

Integrated plasmonic systems have the potential to revolutionise telecom devices [1]. However, the large losses and poor efficiency of plasmonic systems [2] have limited the use of metallic systems as optical circuits. Here we present a hybrid silicon-metallic system in which a single nano-antenna embedded in a single-mode silicon waveguide acts as a tuneable and narrow-band switch. Nanoantennas interact very strongly with light [3], such that when the nano-antenna is at resonance with the waveguide mode up to 80% of the light is blocked by it. This drop in transmission is a consequence of scattering and interference between the dipole and the waveguide mode, which is efficient over the nano-rod resonance bandwidth. The high performance and simplicity of this hybrid device holds great promise for future optoelectronic circuits

Modal Coupling of Single Photon Emitters Within Nanofiber Waveguides

Nanoscale generation of individual photons in confined geometries is an exciting research field aiming at exploiting localized electromagnetic fields for light manipulation. One of the outstanding challenges of photonic systems combining emitters with nanostructured media is the selective channelling of photons emitted by embedded sources into specific optical modes and their transport at distant locations in integrated systems. Here, we show that soft-matter nanofibers, electrospun with embedded emitters, combine subwavelength field localization and large broadband near-field coupling with low propagation losses. By momentum spectroscopy, we quantify the modal coupling efficiency identifying the regime of single-mode coupling. These nanofibers do not rely on resonant interactions, making them ideal for room-temperature operation, and offer a scalable platform for future quantum information technology

Modular microfluidic valve structures based on reversible thermoresponsive ionogel actuators

This paper reports for the first time the use of a crosslinked poly(N- isopropylacrylamide) ionogel encapsulating the ionic liquid 1-Ethyl-3- methylimidazolium ethyl sulphate as a thermoresponsive and modular microfluidic valve. The ionogel presents superior actuation behaviour over its equivalent hydrogel. The ionogel swelling and shrinking mechanisms and kinetics are investigated as well as the performance of the ionogel when integrated as a valve in a microfluidic device. The modular microfluidic valve demonstrates fully reversible on-off behaviour without failure for up to eight actuation cycles and a pressure resistance of 1100 mbar

Scattering of a plasmonic nanoantenna embedded in a silicon waveguide

Plasmonic antennas integrated on silicon devices have large and yet unexplored potential for controlling and routing light signals. Here, we present theoretical calculations of a hybrid silicon-metallic system in which a single gold nanoantenna embedded in a single-mode silicon waveguide acts as a resonance-driven filter. As a consequence of scattering and interference, when the resonance condition of the antenna is met, the transmission drops by 85% in the resonant frequency band. Firstly, we study analytically the interaction between the propagating mode and the antenna by including radiative corrections to the scattering process and the polarization of the waveguide walls. Secondly, we find the configuration of maximum interaction and numerically simulate a realistic nanoantenna in a silicon waveguide. The numerical calculations show a large suppression of transmission and three times more scattering than absorption, consequent with the analytical model. The system we propose can be easily fabricated by standard silicon and plasmonic lithographic methods, making it promising as real component in future optoelectronic circuits.Comment: 10 pages, 5 figure

Traquita La Aguadita: Nuevo exponente del magmatismo alcalino triásico en la Sierra de Valle Fértil, Sierras Pampeanas Occidentales

La Aguadita Trachyte, in Sierra de Valle Fértil, is a new outcrop referring to the Triassic alkaline magmatism. The trachyte body was emplaced along a NNW-trending fault zone overlying the crystalline basement. The trachyte consists mainly of anorthoclase and sanidine as pheno- and microphenocrysts, with lesser amounts of arfvedsonite and ferro-eckermannite in the groundmass. It is moderately evolved in composition with 66.5-69.1 wt.% SiO2 and exhibits a limited compositional range in most of the major elements. The rare earth elements (REE) pattern is somewhat uniform and highly fractionated, being enriched in light REE over heavy REE and showing a prominent negative Eu anomaly. The trachyte is enriched in high field strength elements Nb, Zr, and Y, consistent with typical intraplate alkaline magmatism associated with continental rifting. It is proposed to be genetically linked to other alkaline volcanic rocks outcropping in the area, and generated from the same parental source (i.e., asthenospheric mantle source) through open-system fractional crystallization. ɛNd values of +2.6 are consistent with slightly crustal contamination during trachyte generation. Thus, La Aguadita Trachyte could be the result of a combination of fractional crystallization of mantle-derived basaltic magma and crustal assimilation. Radiometric age dating of 218 ± 7 Ma on the trachyte (K-Ar age, whole rock) expands the range of the alkaline volcanism known in the area to the Upper Triassic, and confirms a regional volcanic event related to uplift in an extensional tectonic environment.La Traquita La Aguadita, en la Sierra de Valle Fértil, es un nuevo afloramiento del magmatismo alcalino triásico. Se dispone sobre el basamento cristalino y su emplazamiento estuvo controlado por una falla de dirección NNO. La traquita está compuesta principalmente por feno y microfenocristales de anortoclasa y sanidina, con cantidades subordinadas de arfvedsonita y ferro-eckermannita en la mesostasis. Es moderadamente evolucionada en composición con 66,5-69,1 % de SiO2 y exhibe un rango composicional restringido para la mayoría de los elementos mayoritarios. El patrón de distribución de los elementos de tierras raras (REE) es uniforme y altamente fraccionado, con enriquecimiento de las LREE respecto de las HREE, y prominente anomalía negativa de Eu. La traquita está enriquecida en elementos de alto potencial iónico como Nb, Zr e Y, congruente con magmatismo alcalino de intraplaca asociado a rifting continental. Se propone su vinculación genética con otras rocas volcánicas alcalinas aflorantes en el área, y su generación a partir de la misma fuente primaria (manto astenosférico) mediante cristalización fraccionada. Los valores de ɛNd = +2.6 son consistentes con un cierto componente de contaminación cortical. De este modo, la Traquita La Aguadita sería resultado de la cristalización fraccionada de magma basáltico derivado del manto combinado con asimilación cortical. La edad radimétrica de 218 ± 7 Ma (K-Ar en roca total) expande el alcance del magmatismo alcalino conocido en el área hasta el Triásico superior, y confirma el carácter regional de este evento volcánico relacionado con la tectónica extensional imperante.Fil: Castro, Brigida Marta Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Geología "Dr. Emiliano Aparicio"; ArgentinaFil: Lopez, Maria Gimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Geología "Dr. Emiliano Aparicio"; ArgentinaFil: Morata, Diego. Universidad de Chile. Facultad de Ciencias Físicas y Matemáticas; Chile. Centro de Excelencia en Geotermia de los Andes; ChileFil: Conte Grand, Alicia Teresita. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Geología "Dr. Emiliano Aparicio"; ArgentinaFil: Pontoriero, Sandra Inés. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Geología "Dr. Emiliano Aparicio"; Argentin

Microstructure and properties of Fe3O4/BaTiO3/epoxy composites

Con el objetivo de estudiar nuevos materiales multipropósito, en este trabajo se analizó la influencia de las partículas de Fe3O4 y BaTiO3 sobre las propiedades magnéticas y dieléctricas de los sistemas Fe3O4/BaTiO3/epoxi. A tal efecto se analizaron los sistemas bifásicos Fe3O4/epoxi y BaTiO3/epoxi y a partir del análisis de los resultados se conformaron los compuestos Fe3O4/BaTiO3/epoxi. En todos los casos los valores de permitividad y pérdidas dieléctricas fueron altamente influenciados por el contenido de carga. En este sentido, los materiales procesados con Fe3O4 presentaron muy elevadas pérdidas dieléctricas para altas concentraciones de carga debido a efectos de percolación y a las propiedades semiconductoras del Fe3O4.The influence of Fe3O4 and BaTiO3 on dielectric and magnetic properties of Fe3O4/BaTiO3/epoxy composites was studied. Initially, biphasic Fe3O4/epoxy and BaTiO3/epoxy composites were analyzed, and based on these results Fe3O4/BaTiO3/epoxy composite were conformed. In all the cases, dielectric properties were influenced by the frequency and filler concentration. In this way, Fe3O4/epoxy composites with high filler concentration showed high dielectric loss due to percolation effects and semiconducting properties of Fe3O4.Fil: Ramajo, Leandro Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Cristobal, Adrian Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Porto Lopez, Jose Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Botta, Pablo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Reboredo, Maria Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Castro, Miriam Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentin

Plasmatic level of neurosin predicts outcome of mild cognitive impairment

<p>Abstract</p> <p>Background</p> <p>Mild Cognitive Impairment (MCI) is a disorder considered to be a transitional stage from health to dementia. Diagnosis of dementias at these early stages is always troublesome because the pathophysiologic events leading to dementia precede clinical symptoms. Thus, the development of biomarkers that can be used to support the diagnosis of dementias at early stages is rapidly becoming a high priority. We have recently reported the value of measuring plasmatic levels of neurosin in the diagnosis of Alzheimer's disease (AD). The aim of this study is to determine whether measuring plasmatic concentration of neurosin is a valuable test to predict progression of MCI.</p> <p>Methods</p> <p>Plasmatic neurosin concentrations were measured in 68 MCI patients and 70 controls subjects. Blood samples were obtained at the beginning of the study. Sixty six patients diagnosed with MCI were observed for 18 months. In 36 patients a second blood sample was obtained at the endpoint.</p> <p>Results</p> <p>The mean value of plasmatic neurosin concentration differs significantly between MCI patients who converted to Dementia with vascular component, those who converted to AD, or those who remained at MCI stage. The relative risk of developing Dementia with vascular component when neurosin levels are higher than 5.25 ng/ml is 13 while the relative risk of developing mild AD when neurosin levels are lower than 5.25 ng/ml is 2. Increases in the levels of neurosin indicate progression to Dementia with vascular component.</p> <p>Conclusion</p> <p>The measurement of plasmatic neurosin level in patients diagnosed with MCI may predict conversion from MCI to Dementia with vascular component. A single measurement is also valuable to estimate the risk of developing AD and Dementia with vascular component. Finally, repeated measurement of plasmatic neurosin might be a useful test to predict outcome in patients with MCI.</p