El trabajo descrito en este documento fue apoyado por una beca del Fondo de Innovación CII-HK / PolyU. Más apoyo fue proporcionado por el Plan de Shenzhen Peacock (KQTD2015071616442225) y el Gobierno chino Programa &quot;Mil Talent&quot; (Y62HB31601). Además, la ayuda del Departamento de Biología Aplicada y Tecnología Química de la Universidad Politécnica de Hong Kong y el Instituto de Hong Kong Universidad Politécnica de Investigación para el Desarrollo Urbano Sostenible (RISUD) es apreciado.

1. Pre-tratamiento de la HGM <ol><li> Coloque la HGM en un vaso de precipitados de 500 ml con 200 ml de alcohol absoluto; la baja densidad de ininterrumpida HGM hace que se suspenda en el alcohol, pero debido a que la densidad de HGM roto es mayor que el del alcohol, se precipita en la solución. Después de 30 min, recoger la HGM suspendido usando una cuchara limpio y seco a 80 ° C en un horno para su posterior aplicación. </li></ol> 2. Síntesis de MCHGM <ol><li> Coloque 5 g de ininterrumpida HGM, 47,5 ml de etanol y 2,5 ml de agua DI en un matraz de tres bocas. Se agita utilizando un motor de mezcla a 400 r / min durante 20 min (pre-mezcla). </li><li> Mezclar 15 g de TBT, 1 g de PFOTES, y 30 ml de alcohol absoluto en un vaso de precipitados de 200 mL. Verter la mezcla en un embudo de presión constante. </li><li> Insertar el embudo de presión constante en uno de los agujeros del matraz de tres bocas. La caída de la mezcla contenida en el embudo de presión constante en el matraz de tres bocas a una velocidad de1 gota por 7 s, que se consigue mediante el ajuste de la válvula del embudo de presión constante. Continuar la reacción durante 3 h. </li><li> Verter la mezcla del matraz de tres bocas en un reactor hidrotermal. Poner el reactor sellado en un manguito de acero adecuado en un horno de 180 ° C durante 6 h. NOTA: Asegúrese de que el reactor tiene una cubierta adecuada. Después de que está cubierto, poner el reactor en el manguito de acero. El manguito también debe ser sellado con una tapa. </li><li> Después de la reacción ha terminado, recoger las muestras en suspensión en el reactor hidrotermal utilizando una cuchara grande. Secar las muestras a 80 ° C durante 4 h para obtener MCHGM. </li></ol> 3. Síntesis de F-SCHGM <ol><li> Añadir 5 g de ininterrumpida HGM, 47,5 ml de etanol absoluto, y 2,5 ml de agua DI a un matraz de tres bocas. Se agita utilizando un motor de mezcla a 400 r / min durante 20 min (pre-mezcla). Mezclar 1 g de PFOTES y 30 ml de etanol absoluto en un vaso de precipitados de 200 mL. Transferir el PFOTES y absoluta emezcla THANOL a un embudo de presión constante. </li><li> Insertar el embudo de presión constante en el matraz de tres bocas. La caída de la mezcla contenida en el embudo de presión constante en el matraz de tres bocas a una velocidad de 1 gota por 7 s. Que la reacción ejecutar durante 3 h. </li><li> Transferir la mezcla del matraz de tres bocas a un reactor hidrotermal. Poner el reactor sellado en un horno de 180 ° C durante 6 h. Después de la reacción ha terminado, recoger las muestras en suspensión en el reactor hidrotermal utilizando una cuchara grande. Secar las muestras a 80 ° C durante 4 h para obtener F-SCHGM. </li></ol> 4. Síntesis de Ti-SCHGM <ol><li> Coloque 5 g de ininterrumpida HGM, 47,5 ml de etanol absoluto, y 2,5 ml de agua DI en un matraz de tres bocas. Se agita a 400 r / min durante 20 min (pre-mezcla). Mezclar 15 g de TBT y 30 ml de etanol absoluto en un vaso de precipitados de 200 mL. La transferencia de la OTC y la mezcla de etanol absoluto a un embudo de presión constante. </li><li> Inserte las constantes-presSeguro de embudo en el matraz de tres bocas. La caída de la mezcla en el embudo de presión constante en el matraz de tres bocas a una velocidad de 1 gota por 7 s. Que la reacción ejecutar durante 3 h. </li><li> Transferir la mezcla del matraz de tres bocas a un reactor hidrotermal. Poner el reactor sellado en un horno de 180 ° C durante 6 h. Recoger las muestras en el reactor hidrotérmico después de la reacción ha terminado. Secar las muestras a 80 ° C durante 4 h para obtener Ti-SCHGM. </li></ol> 5. Caracterizaciones <ol><li> Llevar a cabo las caracterizaciones de DRX en todas las muestras. Recoger los datos utilizando un sistema altamente versátil, polivalente difracción de rayos X con radiación de Cu Ka (λ = 0,15406 nm) y un 2θ que van desde 10 ° a 80 °. </li><li> Adquirir microscopio electrónico de barrido 20, 21 imágenes después de la pulverización de las muestras con oro. Durante las pruebas de SEM, llevar a cabo la EDS está en un área específica. </li><li> Medir laAngulo de contacto mediante el uso de un goniómetro de contacto angular 22; el volumen de la gota de agua debe ser de 10! l. </li><li> Mida el ángulo de deslizamiento 23 al cambiar el ángulo de inclinación de la superficie. Minimizar el ángulo hasta que la gota de agua apenas puede deslizarse hacia abajo. <ol><li> Cinta de palo de doble cara en una hoja de vidrio (tamaño: 26 mm x 76 mm x 2 mm). Con una cuchara, de manera uniforme colocar los polvos (F-SCHGM o MCHGM) en la cinta. Usando un inyector, añadir una gota de agua (volumen: 0,05 ml) a la superficie del polvo. </li><li> Ponga la hoja de vidrio en la plataforma del motor del goniómetro de ángulo de contacto. Incline la hoja de vidrio al inclinarse la plataforma de motor a una velocidad de 1 ° / s. Parar el motor cuando la gota de agua comienza a deslizarse; el ángulo de inclinación es el ángulo de deslizamiento. </li></ol></li><li> Medir los espectros de reflectividad utilizando un espectrofotómetro 24. NOTA: La longitud de onda es de 450 nm a 2550 nm. </li><li> Medir la conductividad térmica de todas las muestrasutilizando un medidor de conductividad térmica 25. </li></ol>

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The authors have nothing to disclose.

En este manuscrito, el paso crítico en el protocolo es el proceso hidrotérmico. Influye en la formación de TiO 2, la reflectividad final, y la superhydrophobicity. El control de la temperatura y tiempo de reacción son también bastante significativo. Si cambian las condiciones de reacción, los productos finales pueden ser defectuoso. Este método proporciona una forma sencilla para sintetizar HGM superhidrofóbica y altamente IR-reflectante en un solo paso. En la investigaci?...

microesferas de vidrio huecas (HGM) son materiales inorgánicos que varían en tamaño de 10 a 100! m. Ellos demuestran muchas características útiles, tales como una excelente dispersión, la capacidad de flujo de alta, baja densidad, y propiedades de aislamiento térmico superiores 1, 2, 3, 4. Debido a su estructura hueca, HGM tiene una conductividad térmica extremadamente baja 10, 11. Por estas razones, se aplican en muchas áreas, incluyendo la ingeniería aeroespacial 5, la exploración de aguas profundas 6, 7, el almacenamiento de hidrógeno 8, 9, etc. Sin embargo, todavía demuestran algunas desventajas, tales como baja resistencia. Además, la luz IR es capaz de transmitir a través de HGM y calentar el sujeto atrás. para elloe, modificaciones de la superficie en HGM son esenciales para reducir la transferencia térmica por radiación. Un método eficaz consiste en recubrir un material de IR de bloqueo sobre la superficie HGM. Como un semiconductor, TiO 2 se ha utilizado en muchas áreas, tales como foto-catálisis 12, 13, el desarrollo de células solares, la fabricación de sensor 14, aplicaciones medioambientales 15, y de almacenamiento de energía 16. Además, también muestra de baja emisividad a la luz visible y banda infrarroja 17, 18, 19. Por lo tanto, para nuestros propósitos, TiO2 era una selección prudente debido a su precio relativamente bajo y alto rendimiento. Sin embargo, el recubrimiento es muy fácil para los contaminantes que ensucian, lo que afecta gravemente a la reflectividad de TiO2. La reflectividad debe reducir gradualmente. Por lo tanto, a self-limpieza es esencial recubrimiento para evitar que el revestimiento de las incrustaciones y para prolongar el tiempo de trabajo de un revestimiento tal. En este manuscrito, se utilizó un método suave-química para desarrollar superhidrofóbica TiO 2 recubierta HGM. Titanato de tetrabutilo (TBT) y 1H, 1H, 2H, 2H-perfluorooctiltrietoxisilano (PFOTES) fueron seleccionados como la fuente de Ti y el agente superhidrofóbica, respectivamente. Ellos fueron hidrolizadas y se depositan sobre la superficie HGM. Luego, después del proceso hidrotérmico, la anatasa TiO 2 formada en la superficie HGM, y las propiedades superhidrófobas mantuvo. Para la comparación, PFOTES HGM de un solo revestido (F-SCHGM) y TiO 2 HGM de un solo recubierto (Ti-SCHGM) se sintetizaron también. El esquema de síntesis se muestra en la Figura 1.

<table><tbody><tr><td>HGM</td><td>Technical Institute of Physics and Chemistry, Chinese Academy of Science</td><td>N/A</td><td>N/A</td></tr><tr><td>TBT</td><td>Sigma-Aldrich</td><td>CAS#: 5593-70-4</td><td>Analytical grade</td></tr><tr><td>Ethyl Alcohol</td><td>Sigma-Aldrich</td><td>CAS#: 64-17-5</td><td>Analytical grade</td></tr><tr><td>PFOTES</td><td>Sigma-Aldrich</td><td>CAS#: 51851-37-7</td><td>98%</td></tr></tbody></table>

tio2-coated hollow glass microspheres with superhydrophobic and high ir-reflective properties synthesized by a soft-chemistry method

Este manuscrito propone un método suave-química para desarrollar microesferas de vidrio huecas superhidrófobas y altamente IR-reflectantes (HGM). La anatasa TiO 2 y un agente superhidrofóbica se recubrieron sobre la superficie HGM en un solo paso. OTC y PFOTES fueron seleccionados como la fuente de Ti y el agente superhidrofóbica, respectivamente. Ambos fueron recubiertos en la HGM, y después del proceso hidrotérmico, la OTC se volvieron a anatasa TiO 2. De esta manera, un PFOTES / TiO2 recubiertas HGM (MCHGM) se preparó. Para la comparación, PFOTES HGM de un solo revestido (F-SCHGM) y TiO 2 HGM de un solo recubierto (Ti-SCHGM) se sintetizaron también. Los PFOTES y TiO 2 revestimientos sobre la superficie HGM se demostraron mediante difracción de rayos X (XRD), microscopía electrónica de barrido (SEM), y caracterizaciones detector de dispersión de energía (EDS). El MCHGM mostró un mayor ángulo de contacto (153 °), pero un ángulo de deslizamiento inferior (16 °) de F-SCHGM, con un ángulo de contacto de 141,26; y un ángulo de 67 ° de deslizamiento. Además, tanto Ti-SCHGM y MCHGM muestran valores de reflectividad IR similares, que eran aproximadamente 5.8% más alto que el HGM original y F-SCHGM. Además, el recubrimiento PFOTES apenas cambió la conductividad térmica. Por lo tanto, F-SCHGM, con una conductividad térmica de 0,0479 W / (m · K), era bastante como la HGM original, que era 0,0475 W / (m · K). MCHGM y Ti-SCHGM también fueron similares. Sus valores de conductividad térmica eran 0,0543 W / (m · K) y 0,0543 W / (m · K), respectivamente. El recubrimiento de TiO 2 aumentó ligeramente la conductividad térmica, pero con el aumento de la reflectividad, se mejoró la propiedad global-aislamiento térmico. Por último, ya que la propiedad reflectante de IR es proporcionada por el revestimiento HGM, si es objeto de falta el recubrimiento, la reflectividad disminuye. Por lo tanto, con el recubrimiento superhidrófobo, la superficie está protegido de ensuciamiento, y su tiempo de vida también se prolonga.

Las pruebas en el paso 4.4 revelan muchas características y propiedades de las muestras. El XRD (Figura 2) refleja la formación de anatasa TiO 2. El SEM (Figura 3) y EDS (Figura 4) muestran el TiO 2 y PFOTES que se recubre sobre la superficie HGM. El ángulo de contacto (Figura 5) y el ángulo de deslizamiento (figura 6) pruebas representan la superhydrophobicity. La prueba de tra...

Watch this Scientific Journal Video about TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method at JoVE.com

TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method

This manuscript proposes a soft-chemistry method to synthesize superhydrophobic, TiO2-coated hollow glass microspheres (HGM) with high IR-reflective properties.

TiO<sub&gt; 2</sub&gt; Recubiertas con microesferas de vidrio huecas con propiedades superhidrófobas y alta IR-reflectantes sintetizado por un método de química suave

This manuscript proposes a soft-chemistry method to develop superhydrophobic and highly IR-reflective hollow glass microspheres (HGM). The anatase TiO2 ...

tio2-coated-hollow-glass-microspheres-with-superhydrophobic-high-ir

Research

JoVE Journal

Chemistry

TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method

10.0K vistas.  City University of Hong Kong. This manuscript proposes a soft-chemistry method to synthesize superhydrophobic, TiO2-coated hollow glass microspheres (HGM) with high IR-reflective properties.

Video: TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method

Fabrication of Silica Ultra High Quality Factor Microresonators

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the quality factor (Q) of the cavity, can be in excess of 500ns for cavities with Q factors above 100 million. As a result of their low material losses, silica microcavities have demonstrated some of the longest photon lifetimes to date1-2. Since a portion of the circulating light extends outside the resonator, these devices can also be used to probe the surroundings. This interaction has enabled numerous experiments in biology, such as single molecule biodetection and antibody-antigen kinetics, as well as discoveries in other fields, such as development of ultra-low-threshold microlasers, characterization of thin films, and cavity quantum electrodynamics studies.3-7
The two primary silica resonant cavity geometries are the microsphere and the microtoroid. Both devices rely on a carbon dioxide laser reflow step to achieve their ultra-high-Q factors (Q&gt;100 million).1-2,8-9 However, there are several notable differences between the two structures. Silica microspheres are free-standing, supported by a single optical fiber, whereas silica microtoroids can be fabricated on a silicon wafer in large arrays using a combination of lithography and etching steps. These differences influence which device is optimal for a given experiment.
Here, we present detailed fabrication protocols for both types of resonant cavities. While the fabrication of microsphere resonant cavities is fairly straightforward, the fabrication of microtoroid resonant cavities requires additional specialized equipment and facilities (cleanroom). Therefore, this additional requirement may also influence which device is selected for a given experiment.
Introduction
An optical resonator efficiently confines light at specific wavelengths, known as the resonant wavelengths of the device. 1-2 The common figure of merit for these optical resonators is the quality factor or Q. This term describes the photon lifetime (&tau;o) within the resonator, which is directly related to the resonator's optical losses. Therefore, an optical resonator with a high Q factor has low optical losses, long photon lifetimes, and very low photon decay rates (1/&tau;o). As a result of the long photon lifetimes, it is possible to build-up extremely large circulating optical field intensities in these devices. This very unique property has allowed these devices to be used as laser sources and integrated biosensors.10
A unique sub-class of resonators is the whispering gallery mode optical microcavity. In these devices, the light is confined in circular orbits at the periphery. Therefore, the field is not completely confined within the device, but evanesces into the environment. Whispering gallery mode optical cavities have demonstrated some of the highest quality factors of any optical resonant cavity to date.9,11 Therefore, these devices are used throughout science and engineering, including in fundamental physics studies and in telecommunications as well as in biodetection experiments. 3-7,12
Optical microcavities can be fabricated from a wide range of materials and in a wide variety of geometries. A few examples include silica and silicon microtoroids, silicon, silicon nitride, and silica microdisks, micropillars, and silica and polymer microrings.13-17 The range in quality factor (Q) varies as dramatically as the geometry. Although both geometry and high Q are important considerations in any field, in many applications, there is far greater leverage in boosting device performance through Q enhancement. Among the numerous options detailed previously, the silica microsphere and the silica microtoroid resonator have achieved some of the highest Q factors to date.1,9 Additionally, as a result of the extremely low optical loss of silica from the visible through the near-IR, both microspheres and microtoroids are able to maintain their Q factors over a wide range of testing wavelengths.18 Finally, because silica is inherently biocompatible, it is routinely used in biodetection experiments.
In addition to high material absorption, there are several other potential loss mechanisms, including surface roughness, radiation loss, and contamination loss.2 Through an optimization of the device size, it is possible to eliminate radiation losses, which arise from poor optical field confinement within the device. Similarly, by storing a device in an appropriately clean environment, contamination of the surface can be minimized. Therefore, in addition to material loss, surface scattering is the primary loss mechanism of concern.2,8
In silica devices, surface scattering is minimized by using a laser reflow technique, which melts the silica through surface tension induced reflow. While spherical optical resonators have been studied for many years, it is only with recent advances in fabrication technologies that researchers been able to fabricate high quality silica optical toroidal microresonators (Q&gt;100 million) on a silicon substrate, thus paving the way for integration with microfluidics.1
The present series of protocols details how to fabricate both silica microsphere and microtoroid resonant cavities. While silica microsphere resonant cavities are well-established, microtoroid resonant cavities were only recently invented.1 As many of the fundamental methods used to fabricate the microsphere are also used in the more complex microtoroid fabrication procedure, by including both in a single protocol it will enable researchers to more easily trouble-shoot their experiments.

We describe the use of a carbon dioxide laser reflow technique to fabricate silica resonant cavities, including free-standing microspheres and on-chip microtoroids. The reflow method removes surface imperfections, allowing long photon lifetimes within both devices. The resulting devices have ultra high quality factors, enabling applications ranging from telecommunications to biodetection.

La fabricación de sílice de alta calidad Ultra microresonators Factor

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the ...

Investigación

Ingeniería

Harvesting Solar Energy by Means of Charge-Separating Nanocrystals and Their Solids

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials offering a superior control over the spatial distribution of charge carriers across material interfaces. As this study demonstrates, a combination of donor-acceptor nanocrystal (NC) domains in a single nanoparticle can lead to the realization of efficient photocatalytic1-5 materials, while a layered assembly of donor- and acceptor-like nanocrystals films gives rise to photovoltaic materials.
Initially the paper focuses on the synthesis of composite inorganic nanocrystals, comprising linearly stacked ZnSe, CdS, and Pt domains, which jointly promote photoinduced charge separation. These structures are used in aqueous solutions for the photocatalysis of water under solar radiation, resulting in the production of H2 gas. To enhance the photoinduced separation of charges, a nanorod morphology with a linear gradient originating from an intrinsic electric field is used5. The inter-domain energetics are then optimized to drive photogenerated electrons toward the Pt catalytic site while expelling the holes to the surface of ZnSe domains for sacrificial regeneration (via methanol). Here we show that the only efficient way to produce hydrogen is to use electron-donating ligands to passivate the surface states by tuning the energy level alignment at the semiconductor-ligand interface. Stable and efficient reduction of water is allowed by these ligands due to the fact that they fill vacancies in the valence band of the semiconductor domain, preventing energetic holes from degrading it. Specifically, we show that the energy of the hole is transferred to the ligand moiety, leaving the semiconductor domain functional. This enables us to return the entire nanocrystal-ligand system to a functional state, when the ligands are degraded, by simply adding fresh ligands to the system4.
To promote a photovoltaic charge separation, we use a composite two-layer solid of PbS and TiO2 films. In this configuration, photoinduced electrons are injected into TiO2 and are subsequently picked up by an FTO electrode, while holes are channeled to a Au electrode via PbS layer6. To develop the latter we introduce a Semiconductor Matrix Encapsulated Nanocrystal Arrays (SMENA) strategy, which allows bonding PbS NCs into the surrounding matrix of CdS semiconductor. As a result, fabricated solids exhibit excellent thermal stability, attributed to the heteroepitaxial structure of nanocrystal-matrix interfaces, and show compelling light-harvesting performance in prototype solar cells7.

A general strategy for the development of charge-separating semiconductor nanocrystal composites deployable for solar energy production is presented. We show that assembly of donor-acceptor nanocrystal domains in a single nanoparticle geometry gives rise to a photocatalytic function, while bulk-heterojunctions of donor-acceptor nanocrystal films can be used for photovoltaic energy conversion.

Captación de energía solar por medio de carga de separación nanocristales y sus sólidos

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

Síntesis y caracterización de supramoleculares Coloides

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Química

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, ...

Synthesizing Sodium Tungstate and Sodium Molybdate Microcapsules via Bacterial Mineral Excretion

We present a method, the bacterial mineral excretion (BME), for synthesizing two kinds of microcapsules, sodium tungstate and sodium molybdate, and the two metal oxides&#39; corresponding nanoparticles&#8212;the former being as small as 22 nm and the latter 15 nm. We fed two strains of bacteria, Shewanella algae and Pandoraea sp., with various concentrations of tungstate or molybdate ions. The concentrations of tungstate and molybdate were adjusted to make microcapsules of different length-to-diameter ratios. We found that the higher the concentration the smaller the nanoparticles were. The nanoparticles came in with three length-to-diameter ratios: 10:1, 3:1 and 1:1, which were achieved by feeding the bacteria respectively with a low concentration, a medium concentration, and a high concentration. The images of the hollow microcapsules were taken via the scanning electron microsphere (SEM). Their crystal structures were verified by X-ray diffraction (XRD)&#8212;the crystal structure of molybdate microcapsules is Na2MoO4 and that of tungstate microcapsules is Na2WO4 with Na2W2O7. These syntheses all were accomplished under a near ambient condition.

This work presents a protocol for manufacture sodium tungstate and sodium molybdate microcapsules via bacteria and their corresponding nanoparticles.

Síntesis de tungstato de sodio y sodio molibdato microcápsulas vía excreción bacteriana de minerales

We present a method, the bacterial mineral excretion (BME), for synthesizing two kinds of microcapsules, sodium tungstate and sodium molybdate, and the ...

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 ...

Photopatterning Proteins and Cells in Aqueous Environment Using TiO2 Photocatalysis

Organic contaminants adsorbed on the surface of titanium dioxide (TiO2) can be decomposed by photocatalysis under ultraviolet (UV) light. Here we describe a novel protocol employing the TiO2 photocatalysis to locally alter cell affinity of the substrate surface. For this experiment, a thin TiO2 film was sputter-coated on a glass coverslip, and the TiO2 surface was subsequently modified with an organosilane monolayer derived from octadecyltrichlorosilane (OTS), which inhibits cell adhesion. The sample was immersed in a cell culture medium, and focused UV light was irradiated to an octagonal region. When a neuronal cell line PC12 cells were plated on the sample, cells adhered only on the UV-irradiated area. We further show that this surface modification can also be performed in situ, i.e., even when cells are growing on the substrate. Proper modification of the surface required an extracellular matrix protein collagen to be present in the medium at the time of UV irradiation. The technique presented here can potentially be employed in patterning multiple cell types for constructing coculture systems or to arbitrarily manipulate cells under culture.

Photopatterning Proteins and Cells in Aqueous Environment Using TiO2 Photocatalysis

We describe a protocol for modifying cell affinity of a scaffold surface in aqueous environment. The method takes advantage of titanium dioxide photocatalysis to decompose organic film in the photo-irradiated region. We show that it can be used to create microdomains of scaffolding proteins, both ex situ and in situ.

Photopatterning proteínas y células en el medio ambiente acuoso Usando TiO<sub&gt; 2</sub&gt; Fotocatálisis

Organic contaminants adsorbed on the surface of titanium dioxide (TiO2) can be decomposed by photocatalysis under ultraviolet (UV) light. Here we describe ...

Bioingeniería

A Facile Synthetic Method to Obtain Bismuth Oxyiodide Microspheres Highly Functional for the Photocatalytic Processes of Water Depuration

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of materials is highly related to its photocatalytic performance, it is necessary to standardize the synthetic methods in order to obtain the most functional architectures and, thus, the highest photocatalytic efficiency. Here, we report a reliable route to obtain BiOI microspheres via the solvothermal process, using Bi(NO3)3 and potassium iodide (KI) as precursors, and ethylene glycol as a template. The synthesis is standardized in a 150 mL autoclave, at 126 &#176;C for 18 h. This results in 2-3 &#181;m-sized mesoporous microspheres, with a relevant specific surface area (61.3 m2/g). Shortening the reaction times in the synthesis results in amorphous structures, while higher temperatures lead to a slight increase in the porosity of the microspheres, with no effect in the photocatalytic performance. The materials are photo-active under UV-A/visible light irradiation for the degradation of the antibiotic ciprofloxacin in water. This method has demonstrated to be effective in interlaboratory tests, obtaining similar BiOI microspheres in Mexican and Chilean research groups.

This article describes a synthetic method to obtain bismuth oxyiodide microspheres, which are highly functional to perform the photocatalytic removal of organic pollutants, such as ciprofloxacin, in water under UV-A/visible light irradiation.

Un fácil método sintético para obtener microesferas de Oxyiodide de bismuto altamente funcional para los procesos fotocatalíticos de depuración de aguas

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of ...

Rendering SiO2/Si Surfaces Omniphobic by Carving Gas-Entrapping Microtextures Comprising Reentrant and Doubly Reentrant Cavities or Pillars

We present microfabrication protocols for rendering intrinsically wetting materials repellent to liquids (omniphobic) by creating gas-entrapping microtextures (GEMs) on them comprising cavities and pillars with reentrant and doubly reentrant features. Specifically, we use SiO2/Si as the model system and share protocols for two-dimensional (2D) designing, photolithography, isotropic/anisotropic etching techniques, thermal oxide growth, piranha cleaning, and storage towards achieving those microtextures. Even though the conventional wisdom indicates that roughening intrinsically wetting surfaces (&#952;o &#60; 90&#176;) renders them even more wetting (&#952;r &#60; &#952;o &#60; 90&#176;), GEMs demonstrate liquid repellence despite the intrinsic wettability of the substrate. For instance, despite the intrinsic wettability of silica &#952;o &#8776; 40&#176; for the water/air system, and &#952;o &#8776; 20&#176; for the hexadecane/air system, GEMs comprising cavities entrap air robustly on immersion in those liquids, and the apparent contact angles for the droplets are &#952;r &#62; 90&#176;. The reentrant and doubly reentrant features in the GEMs stabilize the intruding liquid meniscus thereby trapping the liquid-solid-vapor system in metastable air-filled states (Cassie states) and delaying wetting transitions to the thermodynamically-stable fully-filled state (Wenzel state) by, for instance, hours to months. Similarly, SiO2/Si surfaces with arrays of reentrant and doubly reentrant micropillars demonstrate extremely high contact angles (&#952;r &#8776; 150&#176;&#8211;160&#176;) and low contact angle hysteresis for the probe liquids, thus characterized as superomniphobic. However, on immersion in the same liquids, those surfaces dramatically lose their superomniphobicity and get fully-filled within &#60;1 s. To address this challenge, we present protocols for hybrid designs that comprise arrays of doubly reentrant pillars surrounded by walls with doubly reentrant profiles. Indeed, hybrid microtextures entrap air on immersion in the probe liquids. To summarize, the protocols described here should enable the investigation of GEMs in the context of achieving omniphobicity without chemical coatings, such as perfluorocarbons, which might unlock the scope of inexpensive common materials for applications as omniphobic materials. Silica microtextures could also serve as templates for soft materials.

Rendering SiO2/Si Surfaces Omniphobic by Carving Gas-Entrapping Microtextures Comprising Reentrant and Doubly Reentrant Cavities or Pillars

This work presents microfabrication protocols for achieving cavities and pillars with reentrant and doubly reentrant profiles on SiO2/Si wafers using photolithography and dry etching. Resulting microtextured surfaces demonstrate remarkable liquid repellence, characterized by robust long-term entrapment of air under wetting liquids, despite the intrinsic wettability of silica.

Renderización de superficies SiO2/Si omnifóbicas por el tallado microtexturas que atrapan el gas que comprende cavidades o pilares reentrantes y doblemente reentrantes

We present microfabrication protocols for rendering intrinsically wetting materials repellent to liquids (omniphobic) by creating gas-entrapping ...

Microhoneycomb Monoliths Prepared by the Unidirectional Freeze-drying of Cellulose Nanofiber Based Sols: Method and Extensions

Monolithic honeycomb structures have been attractive to multidisciplinary fields due to their high strength-to-weight ratio. Particularly, microhoneycomb monoliths (MHMs) with micrometer-scale channels are expected as efficient platforms for reactions and separations because of their large surface areas. Up to now, MHMs have been prepared by a unidirectional freeze-drying (UDF) method only from very limited precursors. Herein, we report a protocol from which a series of MHMs consisting of different components can be obtained. Recently, we found that cellulose nanofibers function as a distinct structure-directing agent towards the formation of MHMs through the UDF process. By mixing the cellulose nanofibers with water soluble substances which do not yield MHMs, a variety of composite MHMs can be prepared. This significantly enriches the chemical constitution of MHMs towards versatile applications.

Here, we present a general protocol to prepare a variety of microhoneycomb monoliths (MHMs) in which fluid can pass through with an extremely low pressure drop. MHMs obtained are expected to be used as filters, catalyst supports, flow-type electrodes, sensors and scaffolds for biomaterials.

Monolitos de Microhoneycomb preparados por la liofilización unidireccional de nanofibras de celulosa basan Sols: método y extensiones

Monolithic honeycomb structures have been attractive to multidisciplinary fields due to their high strength-to-weight ratio. Particularly, microhoneycomb ...

TiO

Resumen

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