Este proyecto de investigación ha recibido financiación del Consejo Europeo de Investigación en el Programa de la Comunidad Europea Séptimo Programa Marco (FP7/2007-2013) / ERC acuerdo de subvención n ° 242710 y fue apoyado además por el Human Frontier Science Program y el Programa Emmy Noether del alemán Research Foundation (CDRH 995/2-1).

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P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+lung+physiology+with+xenon+polarization+transfer+contrast+(XTC).">Probing lung physiology with xenon polarization transfer contrast (XTC).</a> Magn. Reson. Med. 44, 349-357 (2000).</li><li>Driehuys, B., Cofer, G. P., Pollaro, J., Mackel, J. B., Hedlund, L. W., Johnson, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+alveolar-capillary+gas+transfer+using+hyperpolarized+129Xe+MRI.">Imaging alveolar-capillary gas transfer using hyperpolarized 129Xe MRI.</a> Proc. Natl. Acad. Sci. U.S.A. 103, 18278-18283 (2006).</li><li>Spence, M. M., Rubin, S. M., Dimitrov, I. E., Ruiz, E. J., Wemmer, D. E., Pines, A., Yao, S. Q., Tian, F., Schultz, P. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functionalized+xenon+as+a+biosensor.">Functionalized xenon as a biosensor.</a> Proc. Natl. Acad. Sci. U.S.A. 98, 10654-10657 (2001).</li><li>Schr&#246;der, L., Lowery, T. J., Hilty, C., Wemmer, D. E., Pines, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+imaging+using+a+targeted+magnetic+resonance+hyperpolarized+biosensor.">Molecular imaging using a targeted magnetic resonance hyperpolarized biosensor.</a> Science. 314, 446-449 (2006).</li><li>Schrank, G., Ma, Z., Schoeck, A., Saam, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+a+low-pressure+high-capacity+129Xe+flow-through+polarizer.">Characterization of a low-pressure high-capacity 129Xe flow-through polarizer.</a> Phys. Rev. A. 80, 063424 (2009).</li><li>Levron, D., Walter, D. K., Appelt, S., Fitzgerald, R. J., Kahn, D., Korbly, S. E., Sauer, K. E., Happer, W., Earles, T. L., Mawst, L. J., Botez, D., Harvey, M., DiMarco, L., Connolly, J. C., M&#246;ller, H. E., Chen, X. J., Cofer, G. P., Johnson, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic+resonance+imaging+of+hyperpolarized+129Xe+produced+by+spin+exchange+with+diode-laser+pumped+Cs.">Magnetic resonance imaging of hyperpolarized 129Xe produced by spin exchange with diode-laser pumped Cs.</a> Appl. Phys. Lett. 73, 2666 (1998).</li><li>Zhou, X., Sun, X. P., Luo, J., Zeng, X. Z., Liu, M. L., Zhan, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+Hyperpolarized+129Xe+Gas+Without+Nitrogen+by+Optical+Pumping+at+133Cs+D2+Line+in+Flow+System.">Production of Hyperpolarized 129Xe Gas Without Nitrogen by Optical Pumping at 133Cs D2 Line in Flow System.</a> Chin. Phys. Lett. 21, 1501-1503 (2004).</li><li>Zhou, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyperpolarized+noble+gases+as+contrast+agents.">Hyperpolarized noble gases as contrast agents.</a> Methods Mol. Biol. 771, 189-204 (2011).</li><li>Seltzer, S. J., Michalak, D. J., Donaldson, M. H., Balabas, M. V., Barber, S. K., Bernasek, S. L., Bouchiat, M. A., Hexemer, A., Hibberd, A. M., Kimball, D. F., Jaye, C., Karaulanov, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Investigation+of+antirelaxation+coatings+for+alkali-metal+vapor+cells+using+surface+science+techniques.">Investigation of antirelaxation coatings for alkali-metal vapor cells using surface science techniques.</a> J. Chem. Phys. 133, 144703 (2010).</li></ol>

No hay conflictos de interés declarado.

Aspectos críticos en la preparación de xenón hiperpolarizado son impurezas de oxígeno en el colector de gas, incluyendo la célula de bombeo y la iluminación suficiente de la célula con luz polarizada circularmente. La prueba de la bombilla mencionado anteriormente es una manera simple de detectar concentraciones perjudiciales de oxígeno durante la transferencia de rubidio. El metal alcalino puede perder su superficie brillante por la vez que se instala en la celda del polarizador. Sin embargo, la vaporización s...

Agentes hiperpolarizados están ganando cada vez más atención por NMR / MRI aplicaciones ya que puede resolver el problema de la sensibilidad en determinadas circunstancias 2. Tres enfoques principales se utilizan actualmente (polarización nuclear dinámica, DNP, para-hidrógeno polarización inducida, PhIP y girar intercambio bombeo óptico, SEOP) que toda preparar una diferencia de giro población aumentó artificialmente fuera un imán RMN antes de la espectroscopia de imagen real o experimento . Aquí se describe la función y operación de una instalación de SEOP que se ha optimizado para la producción de Xe hiperpolarizado 129 utilizado en los experimentos de estado de solución. Un componente esencial es una intensa fuente de luz que emiten fotones infrarrojos de 795 nm. Matrices de diodos láser (LDA) son dispositivos convenientes que proporcionan salida de alta potencia&gt; 100 W a un costo razonable. En muchas configuraciones, la LDA está emitiendo en una fibra óptica que más o menos conserva la polarización de the de luz láser. Para garantizar un proceso de SEOP suficiente esta polarización elíptica debe ser convertido en polarización circular de alta pureza. Los principales componentes de la óptica de polarización se muestran en las Figuras 1 y 2 y la configuración del sistema se explica esquemáticamente en la película suplementario 1. Para polarizar la luz circularmente que sujetar primero el extremo de la fibra óptica a una expansión primaria de haz (por ejemplo, un colimador de fibra) para reducir la densidad de potencia. La luz pasa a través de un divisor de haz polarizante cubo, la generación de luz linealmente polarizada. Mediante la rotación de este cubo se puede determinar el eje preferido de la polarización remanente con un medidor de potencia. Máxima de transmisión corresponde a la situación en la que se alinea el eje rápido del cubo con el eje de polarización de luz principal. Cubos con altos coeficientes de extinción (100.000: 1 o mejor) proporcionar una buena separación de los componentes de polarización. Esto se puede comprobarutilizando un cubo divisor de haz segundos como un analizador que es girado mientras que el primero está alineado para la transmisión máxima de la viga extra-ordinario. Una vez que la polarización lineal de la luz transmitida ha sido confirmada, una placa en onda λ / 4 diseñado para 795 nm se introduce en el haz extraordinaria para convertir lineal en polarización circular. Para este propósito, el eje rápido de la placa de onda es girado por 45 ° con relación al eje del cubo divisor de haz rápido. (Si se desea, la polarización circular del haz reflejado ordinaria con su eje de polarización lineal perpendicular a la viga extra-ordinaria se puede lograr de una manera similar.) La calidad de la polarización circular se puede probar con un cubo divisor de haz segundos que debería suministrar la transmisión constante después de la rotación. Una óptica de haz secundario de expansión (por ejemplo, dos lentes en una configuración de telescopio de Galileo), entonces aumenta el diámetro del haz a completamente illuminate la celda de vidrio para el proceso de bombeo en el interior de una caja de horno. La absorción de la luz láser por Rb vapor en la celda se controla a través de un agujero de pasador detrás de la célula de bombeo en el extremo de la caja: un colimador recoge una atenuado haz IR a analizar con un espectrómetro óptico (ver Figura 3 para el bombeo de configuración celular ). Un mecanismo de calentamiento fuera de la célula de bombeo parcialmente vaporiza una gotita Rb sentado dentro de la célula (Figura 4a) y por lo tanto hace que la absorción de luz láser. Densidad del vapor que se puede ajustar a través del punto de consigna de calefacción del controlador PID respectivo. Las altas temperaturas (aprox. 190 ° C) son buenas para instalaciones compactas en las que el xenón tiene una cantidad limitada de tiempo para construir la polarización. La mezcla de gas que contiene Xe, N 2 y El fluye a través de la célula de bombeo opuesto a la dirección del haz láser (Figura 3). Un campo magnético externo alineado con el haz láser asegura que the fotones infrarrojos están bombeando sólo una transición Rb. La relajación de los estados electrónicos es rápido y debe ser no radiativa para evitar la emisión de fotones IR con &quot;equivocado&quot; polarización. Aquí, el 2 N entra en juego como un gas de enfriamiento rápido. Eventualmente, el sistema Rb se acumula un exceso de población de uno de los subniveles del estado fundamental, mientras que el otro está continuamente agotado por el láser (Figura 5). Xenon ponerse en estrecho contacto con los átomos de Rb experimenta interacciones spin-spin y la polarización de espín de electrones se transfiere a núcleos de Xe en los flip-flops procesos. El gas hiperpolarizado que fluye hacia fuera de la célula de bombeo contiene trazas de vapor de Rb que el condensado en la pared del tubo dentro de unos pocos cm de la salida debido a la baja temperatura (similar a la Figura 4b). En aplicaciones in vivo, sin embargo, requeriría la eliminación adicional del metal alcalino (por ejemplo, a través de una trampa de frío), mientras que in vitro experimeNTS puede realizarse con seguridad con el gas cuando sale del hiperpolarizador. Tubo de Teflon conecta la salida polarizador con la entrada de un aparato de vidrio para llevar a cabo experimentos de RMN en soluciones de prueba. Controladores de flujo másico se utilizan para ajustar la cantidad de Xe que fluye en la configuración de la RMN. Son provocados por comandos en la secuencia de pulsos de RMN. Después de comprobar la mejora de la polarización alcanzada, el gas puede ser usado como un agente de contraste de RMN / RM experimentos en estado de solución. Xe tiene una cierta solubilidad en agua (4,5 mM / atm) y otros disolventes. Por lo tanto, ya puede servir por sí mismo como un agente de contraste para visualizar la distribución de algunos líquidos. Sin embargo, también es posible unir los núcleos de RMN-activo a ciertas moléculas con el fin de adquirir molecular específico de información a través del gas inerte lo contrario. Al proporcionar un anfitrión molecular para el Xe disuelto, es posible conferir la especificidad molecular para la señal de Xe NMR. Esto proporciona la oportunidad deagentes de contraste diseño funcionalizadas - también llamado biosensores - cuando dicha estructura de acogida está acoplado a una unidad de dirección que se une a los analitos específicos de interés biomédico (Figura 6). Mejora de la sensibilidad se requiere más cuando el biosensor debe ser detectado en concentraciones que son bajos para los agentes de contraste de RM (&lt;100 mM). Esto se puede conseguir por intercambio químico de transferencia de saturación (CET). Este método detecta el biosensor indirectamente mediante la destrucción de la magnetización de la jaula Xe y observando el cambio de la señal de Xe libre en solución. Puesto que los núcleos hiperpolarizado se reemplazan continuamente después de algunos 10 ms, la transferencia de muchos núcleos de 100 hasta 1000 la información a la piscina detectado y amplificar la señal de ca. 10 3-veces (ver película 2).

<table border="1"><tbody><tr><td> Nombre del reactivo </td><td> Empresa </td><td> Número de catálogo </td><td> Comentarios (opcional) </td></tr><tr><td> Rb lingote </td><td> Sigma-Aldrich </td><td> 276332-1G </td><td></td></tr><tr><td> P 4 O 10 </td><td> Sigma-Aldrich </td><td> 79610-500G </td><td></td></tr><tr><td> Ar </td><td> Praxair </td><td></td><td></td></tr><tr><td> Xe </td><td> Sigma-Aldrich </td><td> 00472-1EA </td><td></td></tr><tr><td> O 2 </td><td> Sigma-Aldrich </td><td> 00476-1EA </td><td></td></tr><tr><td> Sistema láser </td><td> Los láseres QPC / Operaciones láser </td><td> Brightlock 50 </td><td></td></tr><tr><td> Sistema de vacío </td><td> Pfeiffer </td><td> HiCube </td><td></td></tr><tr><td> Termopares </td><td> NewportOmega </td><td> SA2F-KI-3M </td><td></td></tr><tr><td> Silicio calentador </td><td> Newport Omega </td><td> FMA5514 </td><td></td></tr><tr><td> Transductor de presión </td><td> Newport Omega </td><td> PR 33X-V-10 </td><td></td></tr><tr><td> Proceso de metro </td><td> Newport Omega </td><td> INFCP-100B </td><td></td></tr><tr><td> Controladores de flujo másico </td><td> Newport Omega </td><td> MFC </td><td></td></tr><tr><td> Controladores PID </td><td> Newport Omega </td><td> CN7800 </td><td></td></tr><tr><td> Software de Control </td><td> Newport Omega </td><td> DASYLab </td><td></td></tr><tr><td> Adquisición de datos </td><td> Newport Omega </td><td> Daqboard 3000 </td><td></td></tr><tr><td> Sensor de vacío </td><td> Oerlikon </td><td> TTR91 </td><td></td></tr><tr><td> Controlador de Vacío </td><td> Vacom </td><td> MVC-3 </td><td></td></tr><tr><td> Colimador de haz </td><td> Thorlabs </td><td> F810SMA-780 </td><td></td></tr><tr><td> Divisor de haz polarizante cubo </td><td> Thorlabs </td><td> GL15-B </td><td></td></tr><tr><td> λ / 4 de onda placa </td><td> Thorlabs </td><td> WPQ10M-780 </td><td></td></tr><tr><td> Lentes de haz de expansión </td><td> Thorlabs </td><td></td><td></td></tr><tr><td> Espectrómetro óptico </td><td> Ocean Optics </td><td> HR4000 </td><td></td></tr><tr><td> Fibra óptica </td><td> Ocean Optics </td><td></td><td></td></tr><tr><td> Baja presión tubo de RMN </td><td> Wilmad </td><td> 513-7LPV-7 </td><td></td></tr><tr><td> Tubo de RMN de 5 mm </td><td> Sigma-Aldrich </td><td> HX58.1 </td><td></td></tr><tr><td> Bobinas de Helmholtz </td><td> Phywe </td><td> 06960-00 </td><td></td></tr><tr><td> Fused silica capilares </td><td> Polymicro </td><td> TSG 250350 </td><td></td></tr></tbody></table>

hyperpolarized xenon for nmr and mri applications

Resonancia magnética nuclear (RMN) y espectroscopia de resonancia magnética (RM) sufren de baja sensibilidad intrínseca porque incluso fuertes campos magnéticos externos de ~ 10 T generar sólo una pequeña detectable red de magnetización de la muestra a temperatura ambiente 1. Por lo tanto, la mayoría de las aplicaciones de NMR y MRI se basan en la detección de moléculas en concentración relativamente alta (por ejemplo, agua para la formación de imágenes de tejido biológico), o requieren tiempos excesivos de adquisición. Esto limita nuestra capacidad de explotar la especificidad molecular muy útil de señales de RMN para muchas aplicaciones bioquímicas y médicas. Sin embargo, nuevos enfoques han surgido en los últimos años: La manipulación de las especies de giro detectados antes de la detección en el interior del imán de RMN / MRI puede aumentar drásticamente la magnetización y por lo tanto permite la detección de moléculas a una concentración mucho más baja 2. Aquí, se presenta un método para la polarización de una mezcla de gas xenón (2-5% Xe, 10%N 2, El balance) en una configuración compacta con una ca. 16000-fold aumento de la señal. Moderna línea de estrechamiento de láseres de diodo de polarización permitir eficiente 7 y el uso inmediato de la mezcla de gas, incluso si el gas noble no se separa de los otros componentes. El aparato SEOP se explica y determinación de la polarización de espín logrado se demuestra para el control de la ejecución del método. El gas hiperpolarizado se puede utilizar para obtener imágenes de espacio vacío, incluyendo formación de imágenes de flujo de gas o estudios de difusión en las interfaces con otros materiales 8,9. Además, la señal de RMN Xe es extremadamente sensible a su entorno molecular 6. Esto permite la opción de usarlo como un agente de contraste de RMN / RM cuando se disuelve en solución acuosa con funcionalizados anfitriones moleculares que temporalmente atrapar el gas de 10,11. La detección directa y de alta sensibilidad de detección indirecta de tales construcciones se demuestra tanto en modo espectroscópico y de imagen. &lt;/ P&gt;

Watch this Scientific Journal Video about Hyperpolarized Xenon for NMR and MRI Applications at JoVE.com

Hyperpolarized Xenon for NMR and MRI Applications

La producción de xenón hiperpolarizado por medio de intercambio de espín óptica de bombeo (SEOP) se describe. Este método produce un ~ 10000-veces el aumento de la polarización de espín nuclear de Xe-129 y tiene aplicaciones en espectroscopia de resonancia magnética nuclear y de imagen. Ejemplos de fase gas y los experimentos solución de estado se dan.

Xenón hiperpolarizado para RMN y MRI Aplicaciones

Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) suffer from intrinsic low sensitivity because even strong external magnetic fields of ~10 ...

hyperpolarized-xenon-for-nmr-and-mri-applications

Research

JoVE Journal

Engineering

19.4K vistas.  Leibniz-Institut für Molekulare Pharmakologie. La producción de xenón hiperpolarizado por medio de intercambio de espín óptica de bombeo (SEOP) se describe. Este método produce un ~ 10000-veces el aumento de la polarización de espín nuclear de Xe-129 y tiene aplicaciones en espectroscopia de resonancia magnética nuclear y de imagen. Ejemplos de fase gas y los experimentos solución de estado se dan.

Video: Hyperpolarized Xenon for NMR and MRI Applications

Solid-state Graft Copolymer Electrolytes for Lithium Battery Applications

Battery safety has been a very important research area over the past decade. Commercially available lithium ion batteries employ low flash point (&lt;80 &deg;C), flammable, and volatile organic electrolytes. These organic based electrolyte systems are viable at ambient temperatures, but require a cooling system to ensure that temperatures do not exceed 80 &deg;C. These cooling systems tend to increase battery costs and can malfunction which can lead to battery malfunction and explosions, thus endangering human life. Increases in petroleum prices lead to a huge demand for safe, electric hybrid vehicles that are more economically viable to operate as oil prices continue to rise. Existing organic based electrolytes used in lithium ion batteries are not applicable to high temperature automotive applications. A safer alternative to organic electrolytes is solid polymer electrolytes. This work will highlight the synthesis for a graft copolymer electrolyte (GCE) poly(oxyethylene) methacrylate (POEM) to a block with a lower glass transition temperature (Tg) poly(oxyethylene) acrylate (POEA). The conduction mechanism has been discussed and it has been demonstrated the relationship between polymer segmental motion and ionic conductivity indeed has a Vogel-Tammann-Fulcher (VTF) dependence. Batteries containing commercially available LP30 organic (LiPF6 in ethylene carbonate (EC):dimethyl carbonate (DMC) at a 1:1 ratio) and GCE were cycled at ambient temperature. It was found that at ambient temperature, the batteries containing GCE showed a greater overpotential when compared to LP30 electrolyte. However at temperatures greater than 60 &deg;C, the GCE cell exhibited much lower overpotential due to fast polymer electrolyte conductivity and nearly the full theoretical specific capacity of 170 mAh/g was accessed.

Lithium ion batteries employ flammable and volatile organic electrolytes that are suitable for ambient temperature applications. A safer alternative to organic electrolytes are solid polymer batteries. Solid polymer batteries operate safely at high temperatures (&gt;120 &deg;C), thus making them applicable to high temperature applications such as deep oil drilling and hybrid electric vehicles. This paper will discuss (a) the polymer synthesis, (b) the polymer conduction mechanism, and (c) provide temperature cycling for both solid polymer and organic electrolytes.

Los electrolitos copolímero de injerto de estado sólido para aplicaciones de batería de litio

Battery safety has been a very important research area over the past decade. Commercially available lithium ion batteries employ low flash point (&lt;80 ...

Investigación

Ingeniería

Use of a Multi-compartment Dynamic Single Enzyme Phantom for Studies of Hyperpolarized Magnetic Resonance Agents

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due to fundamental constraints imposed by the hyperpolarized state, exotic imaging and reconstruction techniques are commonly used. A practical system for characterization of dynamic, multi-spectral imaging methods is critically needed. Such a system must reproducibly recapitulate the relevant chemical dynamics of normal and pathological tissues. The most widely utilized substrate to date is hyperpolarized [1-13C]-pyruvate for assessment of cancer metabolism. We describe an enzyme-based phantom system that mediates the conversion of pyruvate to lactate. The reaction is initiated by injection of the hyperpolarized agent into multiple chambers within the phantom, each of which contains varying concentrations of reagents that control the reaction rate. Multiple compartments are necessary to ensure that imaging sequences faithfully capture the spatial and metabolic heterogeneity of tissue. This system will aid the development and validation of advanced imaging strategies by providing chemical dynamics that are not available from conventional phantoms, as well as control and reproducibility that is not possible in vivo.

A multi-compartment dynamic phantom is used to simulate some biology of interest for metabolic studies using hyperpolarized magnet resonance agents.

El uso de un de varios compartimentos dinámico sola enzima fantasma de Estudios de hiperpolarizados Agentes de Resonancia Magnética

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due ...

Three-dimensional Particle Tracking Velocimetry for Turbulence Applications: Case of a Jet Flow

3D-PTV is a quantitative flow measurement technique that aims to track the Lagrangian paths of a set of particles in three dimensions using stereoscopic recording of image sequences. The basic components, features, constraints and optimization tips of a 3D-PTV topology consisting of a high-speed camera with a four-view splitter are described and discussed in this article. The technique is applied to the intermediate flow field (5 &#60;x/d &#60;25) of a circular jet at Re &#8776; 7,000. Lagrangian flow features and turbulence quantities in an Eulerian frame are estimated around ten diameters downstream of the jet origin and at various radial distances from the jet core. Lagrangian properties include trajectory, velocity and acceleration of selected particles as well as curvature of the flow path, which are obtained from the Frenet-Serret equation. Estimation of the 3D velocity and turbulence fields around the jet core axis at a cross-plane located at ten diameters downstream of the jet is compared with literature, and the power spectrum of the large-scale streamwise velocity motions is obtained at various radial distances from the jet core.

A three-dimensional particle tracking velocimetry (3D-PTV) system based on a high-speed camera with a four-view splitter is described here. The technique is applied to a jet flow from a circular pipe in the vicinity of ten diameters downstream at Reynolds number Re &#8776; 7,000.

Tridimensional de velocimetría de seguimiento de partículas para aplicaciones de turbulencia: Caso de un Flujo Jet

3D-PTV is a quantitative flow measurement technique that aims to track the Lagrangian paths of a set of particles in three dimensions using stereoscopic ...

Colloidal Synthesis of Nanopatch Antennas for Applications in Plasmonics and Nanophotonics

We present a method for colloidal synthesis of silver nanocubes and the use of these in combination with a smooth gold film, to fabricate plasmonic nanoscale patch antennas. This includes a detailed procedure for the fabrication of thin films with a well-controlled thickness over macroscopic areas using layer-by-layer deposition of polyelectrolyte polymers, namely poly(allylamine) hydrochloride (PAH) and polystyrene sulfonate (PSS). These polyelectrolyte spacer layers serve as a dielectric gap in between silver nanocubes and a gold film. By controlling the size of the nanocubes or the gap thickness, the plasmon resonance can be tuned from about 500 nm to 700 nm. Next, we demonstrate how to incorporate organic sulfo-cyanine5 carboxylic acid (Cy5) dye molecules into the dielectric polymer gap region of the nanopatch antennas. Finally, we show greatly enhanced fluorescence of the Cy5 dyes by spectrally matching the plasmon resonance with the excitation energy and the Cy5 absorption peak. The method presented here enables the fabrication of plasmonic nanopatch antennas with well-controlled dimensions utilizing colloidal synthesis and a layer-by-layer dip-coating process with the potential for low cost and large-scale production. These nanopatch antennas hold great promise for practical applications, for example in sensing, ultrafast optoelectronic devices and for high-efficiency photodetectors.

A protocol for the colloidal synthesis of silver nanocubes and fabrication of plasmonic nanoscale patch antennas with sub-10 nm gaps is presented.

Coloidal Síntesis de Nanopatch antenas para aplicaciones en Plasmonics y Nanofotónica

We present a method for colloidal synthesis of silver nanocubes and the use of these in combination with a smooth gold film, to fabricate plasmonic ...

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, interface precipitation, and mini-emulsion. In all methods, well-defined, micrometer-sized spheres are obtained from a self-assembling process in solution. The vapor diffusion method can result in spheres with the highest sphericity and surface smoothness, yet the types of the polymers able to form these spheres are limited. On the other hand, in the mini-emulsion method, microspheres can be made from various types of polymers, even from highly crystalline polymers with coplanar, &#960;-conjugated backbones. The photoluminescent (PL) properties from single isolated microspheres are unusual: the PL is confined inside the spheres, propagates at the circumference of the spheres via the total internal reflection at the polymer/air interface, and self-interferes to show sharp and periodic resonant PL lines. These resonating modes are so-called "whispering gallery modes" (WGMs). This work demonstrates how to measure WGM PL from single isolated spheres using the micro-photoluminescence (&#181;-PL) technique. In this technique, a focused laser beam irradiates a single microsphere, and the luminescence is detected by a spectrometer. A micromanipulation technique is then used to connect the microspheres one by one and to demonstrate the intersphere PL propagation and color conversion from coupled microspheres upon excitation at the perimeter of one sphere and detection of PL from the other microsphere. These techniques, &#181;-PL and micromanipulation, are useful for experiments on micro-optic application using polymer materials.

Protocols for the synthesis of microspheres from polymers, the manipulation of microspheres, and micro-photoluminescence measurements are presented.

Fabricación de microesferas de polímero para aplicaciones de resonador óptico y láser

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, ...

Protocol for the Evaluation of MRI Artifacts Caused by Metal Implants to Assess the Suitability of Implants and the Vulnerability of Pulse Sequences

As the number of magnetic resonance imaging (MRI) scanners and patients with medical implants is constantly growing, radiologists increasingly encounter metallic implant-related artifacts in MRI, resulting in reduced image quality. Therefore, the MRI suitability of implants in terms of artifact volume, as well as the development of pulse sequences to reduce image artifacts, are becoming more and more important. Here, we present a comprehensive protocol which allows for a standardized evaluation of the artifact volume of implants on MRI. Furthermore, this protocol can be used to analyze the vulnerability of different pulse sequences to artifacts. The proposed protocol can be applied to T1- and T2-weighted images with or without fat-suppression and all passive implants. Furthermore, the procedure enables the separate and three-dimensional identification of signal loss and pile-up artifacts. As previous investigations differed greatly in evaluation methods, the comparability of their results was limited. Thus, standardized measurements of MRI artifact volumes are necessary to provide better comparability. This may improve the development of the MRI suitability of implants and better pulse sequences to finally improve patient care.

We describe a standardized method to evaluate magnetic resonance imaging artifacts caused by implants to estimate the suitability of the implants for magnetic resonance imaging and/or the vulnerability of different pulse sequences to metallic artifacts simultaneously.

Protocolo para la evaluación de MRI artefactos causados por el Metal de los implantes para evaluar la idoneidad de los implantes y la vulnerabilidad de secuencias de pulso

As the number of magnetic resonance imaging (MRI) scanners and patients with medical implants is constantly growing, radiologists increasingly encounter ...

Fabrication of Superhydrophobic Metal Surfaces for Anti-Icing Applications

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in industry. The wettability of the produced surface was analyzed by bouncing drop experiments and the topography was analyzed by confocal microscopy. In addition, we show various methodologies to measure its durability and anti-icing properties. Superhydrophobic surfaces hold a special texture that must be preserved to keep their water-repellency. To fabricate durable surfaces, we followed two strategies to incorporate a resistant texture. The first strategy is a direct incorporation of roughness to the metal substrate by acid etching. After this surface texturization, the surface energy was decreased by silanization or fluoropolymer deposition. The second strategy is the growth of a ceria layer (after surface texturization) that should enhance the surface hardness and corrosion resistance. The surface energy was decreased with a stearic acid film.
The durability of the superhydrophobic surfaces was examined by a particle impact test, mechanical wear by lateral abrasion, and UV-ozone resistance. The anti-icing properties were explored by studying the ability to repeal subcooled water, freezing delay, and ice adhesion.

We illustrate several methodologies to produce superhydrophobic metal surfaces and to explore their durability and anti-icing properties.

Fabricación de superficies metálicas superhidrófobos para aplicaciones anti-hielo

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in ...

Controllable Nucleation of Cavitation from Plasmonic Gold Nanoparticles for Enhancing High Intensity Focused Ultrasound Applications

In this study, plasmonic gold nanoparticles were simultaneously exposed to pulsed near-infrared laser light and high intensity focused ultrasound (HIFU) for the controllable nucleation of cavitation in tissue-mimicking gel phantoms. This in vitro protocol was developed to demonstrate the feasibility of this approach, for both enhancement of imaging and therapeutic applications for cancer. The same apparatus can be used for both imaging and therapeutic applications by varying the exposure duration of the HIFU system. For short duration exposures (10 &#181;s), broadband acoustic emissions were generated through the controlled nucleation of inertial cavitation around the gold nanoparticles. These emissions provide direct localization of nanoparticles. For future applications, these particles may be functionalized with molecular-targeting antibodies (e.g. anti-HER2 for breast cancer) and can provide precise localization of cancerous regions, complementing routine diagnostic ultrasound imaging. For continuous wave (CW) exposures, the cavitation activity was used to increase the localized heating from the HIFU exposures resulting in larger thermal damage in the gel phantoms. The acoustic emissions generated from inertial cavitation activity during these CW exposures was monitored using a passive cavitation detection (PCD) system to provide feedback of cavitation activity. Increased localized heating was only achieved through the unique combination of nanoparticles, laser light and HIFU. Further validation of this technique in pre-clinical models of cancer is necessary.

This protocol demonstrates the controllable nucleation of cavitation in gel phantoms, through simultaneous exposure to both near-infrared pulsed laser light and high intensity focused ultrasound (HIFU). The cavitation activity can then be used for enhancing imaging and/or therapeutic uses of HIFU.

Nucleación controlable de la cavitación de la plasmónica nanopartículas de oro para aumentar la intensidad alta enfocada ultrasonido aplicaciones

In this study, plasmonic gold nanoparticles were simultaneously exposed to pulsed near-infrared laser light and high intensity focused ultrasound (HIFU) ...

Optimization, Test and Diagnostics of Miniaturized Hall Thrusters

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without attendance and adjustment. Thermochemical thrusters which utilize thermodynamic properties of gases as a means of acceleration have physical limitations on their exhaust gas velocity, resulting in low efficiency. Moreover, these engines demonstrate extremely low efficiency at small thrusts and may be unsuitable for continuously operating systems which provide real-time adaptive control of the spacecraft orientation, velocity and position. In contrast, electric propulsion systems which use electromagnetic fields to accelerate ionized gases (i.e., plasmas) do not have any physical limitation in terms of exhaust velocity, allowing virtually any mass efficiency and specific impulse. Low-thrust Hall thrusters have a lifetime of several thousand hours. Their discharge voltage ranges between 100 and 300 V, operating at a nominal power of &lt;1 kW. They vary from 20 to 100 mm in size. Large Hall thrusters can provide fractions of millinewton of thrust. Over the past few decades, there has been an increasing interest in small mass, low power, and high efficiency propulsion systems to drive satellites of 50-200 kg. In this work, we will demonstrate how to build, test, and optimize a small (30 mm) Hall thruster capable of propelling a small satellite weighing about 50 kg. We will show the thruster operating in a large space environment simulator, and describe how thrust is measured and electric parameters, including plasma characteristics, are collected and processed to assess key thruster parameters. We will also demonstrate how the thruster is optimized to make it one of the most efficient small thrusters ever built. We will also address challenges and opportunities presented by new thruster materials.

Here, we present a protocol to test and optimize space propulsion systems based on miniaturized Hall-type thrusters.

Optimización, pruebas y diagnóstico de propulsores Hall miniatura

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without ...

Application of a Coupling Agent to Improve the Dielectric Properties of Polymer-Based Nanocomposites

In this work, an easy, low-cost, and widely applicable method was developed to improve the compatibility between the ceramic fillers and the polymer matrix by adding 3-aminopropyltriethoxysilane (KH550) as a coupling agent during the fabrication process of BaTiO3-P(VDF-CTFE) nanocomposites through solution casting. Results show that the use of KH550 can modify the surface of ceramic nanofillers; therefore, good wettability on the ceramic-polymer interface was achieved, and the enhanced energy storage performances were obtained by a suitable amount of the coupling agent. This method can be used to prepare flexible composites, which is highly desirable for the production of high-performance film capacitors. If an excessive amount of coupling agent is used in the process, the non-attached coupling agent can participate in complex reactions, which leads to a decrease in dielectric constant and an increase in dielectric loss.

Here, we demonstrate a simple and low-cost solution-casting process to improve the compatibility between the filler and the matrix of polymer-based nanocomposites using surface modified BaTiO3 fillers, which can effectively enhance the energy density of the composites.

Aplicación de un agente de acoplamiento para mejorar las propiedades dieléctricas de los nanocompuestos basados en polímeros

In this work, an easy, low-cost, and widely applicable method was developed to improve the compatibility between the ceramic fillers and the polymer ...