O trabalho descrito neste trabalho foi apoiado por uma bolsa do Fundo de Inovação CII-HK / PolyU. Um apoio adicional foi fornecido pelo Plano de Shenzhen Peacock (KQTD2015071616442225) eo Governo chinês Programa &quot;Mil Talentos&quot; (Y62HB31601). Além disso, a ajuda do Departamento de Biologia Aplicada e Tecnologia Química da Universidade Politécnica de Hong Kong e do Instituto de Hong Kong Universidade Politécnica Pesquisa para o Desenvolvimento Urbano Sustentável (RISUD) é apreciado.

1. Pré-tratamento de HGM <ol><li> Coloque a HGM para uma proveta de 500 mL com 200 mL de álcool absoluto; a baixa densidade de HGM ininterrupta faz com que ele a suspender no álcool, mas, porque a densidade de HGM quebrado é maior do que a de álcool, que precipita na solução. Depois de 30 minutos, recolher o HGM suspensa utilizando uma colher limpo e seco a 80 ° C numa estufa para posterior aplicação. </li></ol> 2. Síntese de MCHGM <ol><li> Colocar 5 g de HGM ininterrupta, 47,5 ml de etanol, e 2,5 ml de água Dl em um balão de três tubuladuras. Agita-se usando um motor de agitação a 400 r / min durante 20 minutos (pré-mistura). </li><li> Misturar 15 g de TBT, 1 g de PFOTES, e 30 ml de álcool absoluto num copo de 200 mL. Verter a mistura dentro de um funil de pressão constante. </li><li> Inserir o funil de pressão constante em um dos furos do balão de três tubuladuras. Deixar cair a mistura contida no funil de pressão constante dentro do balão de três tubuladuras a uma velocidade de1 gota por 7 s, o que é conseguido através do ajuste da válvula do funil de pressão constante. Continuar a reacção durante 3 h. </li><li> Verter a mistura a partir do balão de três tubuladuras num reactor hidrotérmica. Colocar o reactor selado numa manga de aço adequada num forno a 180 ° C durante 6 h. NOTA: Certifique-se de que o reator tem uma cobertura adequada. Depois que é coberto, colocar o reactor para dentro da manga de aço. A manga também deve ser selado com uma tampa. </li><li> Depois da reacção é longo, recolher as amostras em suspensão no reactor hidrotérmica utilizando uma colher grande. Secam-se as amostras a 80 ° C durante 4 h para se obter MCHGM. </li></ol> 3. Síntese de F-SCHGM <ol><li> Adicionar 5 g de HGM ininterrupta, 47,5 ml de etanol absoluto, e 2,5 mL de ua DI para um frasco de três gargalo. Agita-se usando um motor de agitação a 400 r / min durante 20 minutos (pré-mistura). Misturar 1 g de PFOTES e 30 ml de etanol absoluto num copo de 200 mL. Transferir a PFOTES e absoluto eThanol mistura para um funil de pressão constante. </li><li> Inserir o funil de pressão constante dentro do balão de três tubuladuras. Deixar cair a mistura contida no funil de pressão constante dentro do balão de três tubuladuras a uma velocidade de uma gota por 7 s. Deixe que a reaco executado durante 3 h. </li><li> Transferir a mistura a partir do balão de três tubuladuras de um reactor hidrotérmica. Colocar o reactor selado num forno de 180 ° C durante 6 h. Depois da reacção é longo, recolher as amostras em suspensão no reactor hidrotérmica utilizando uma colher grande. Secam-se as amostras a 80 ° C durante 4 h para se obter F-SCHGM. </li></ol> 4. Stese de Ti-SCHGM <ol><li> Colocar 5 g de HGM ininterrupta, 47,5 ml de etanol absoluto, e 2,5 ml de água Dl em um balão de três tubuladuras. Agita-se a 400 r / min durante 20 minutos (pré-mistura). Misturar 15 g de TBT e 30 ml de etanol absoluto num copo de 200 mL. Transferir o TBT e mistura de etanol absoluto para um funil de pressão constante. </li><li> Insira as constantes-prescerteza funil no frasco de três gargalo. Deixar cair a mistura no funil de pressão constante dentro do balão de três tubuladuras a uma velocidade de uma gota por 7 s. Deixe que a reaco executado durante 3 h. </li><li> Transferir a mistura a partir do balão de três tubuladuras de um reactor hidrotérmica. Colocar o reactor selado num forno de 180 ° C durante 6 h. Recolher as amostras no reactor hidrotérmica após a reacção é longo. Secam-se as amostras a 80 ° C durante 4 h para se obter Ti-SCHGM. </li></ol> 5. Caracterizações <ol><li> Realizar caracterizações de DRX em todas as amostras. Recolher os dados utilizando um sistema de difracção altamente versátil, de múltiplos propósitos de raios X com radiação Cu Ka (λ = 0,15406 nm) e um 2θ variando de 10 ° a 80 °. </li><li> Adquirir microscópio de exploração de electrões 20, 21 imagens após a pulverização das amostras com ouro. Durante os testes de SEM, conduzir a EDS está em uma área específica. </li><li> Meça aângulo de contato usando um goniómetro de ângulo de contacto 22; o volume da gota de água deve ser de 10 mL. </li><li> Medir o ângulo de deslizamento 23, alterando o ângulo de inclinação da superfície. Minimizar o ângulo até que a gota de água pode simplesmente deslizar para baixo. <ol><li> Cole fita de face dupla de uma folha de vidro (tamanho: 26 milímetros x 76 mm x 2 mm). Usando uma colher, de maneira uniforme colocar os pós (F-SCHGM ou MCHGM) sobre a fita. Utilizando um injector, adicionar uma gota de água (volume: 0,05 mL) para a superfície do pó. </li><li> Coloque a folha de vidro na plataforma do motor do goniômetro contato angular. Inclinar a folha de vidro, inclinando-se a plataforma de motor a uma taxa de 1 ° / s. Parar o motor quando a gota de água começa a deslizar; o ângulo de inclinação é o ângulo de deslizamento. </li></ol></li><li> Medir os espectros de refletividade utilizando um espectrofotetro 24. NOTA: O comprimento de onda é de 450 nm a 2550 nm. </li><li> Medir a condutividade térmica de todas as amostrasutilizando um medidor de condutividade térmica 25. </li></ol>

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The authors have nothing to disclose.

Neste texto, o passo crítico no protocolo é o processo hidrotermal. Ela influencia a formação de TiO 2, a ref lectividade final, e o superhydrophobicity. O controlo da temperatura e tempo de reacção também são bastante significativas. Se as condições de reação mudam, os produtos finais podem ser falho. Este método oferece uma maneira simples de sintetizar e hidrofóbicas altamente IR-reflexivo HGM em um passo. Na investigação anterior, as propriedades hidrofóbicas ...

microesferas de vidro ocas (HGM) são materiais inorgânicos que variam em tamanho de 10 a 100? m. Eles demonstram muitas características úteis, tais como a excelente dispersão, capacidade de fluxo elevada, baixa densidade, e propriedades de isolamento térmico superiores 1, 2, 3, 4. Devido à sua estrutura oca, HGM têm uma condutividade térmica extremamente baixa 10, 11. Por estas razões, eles são aplicadas em muitas áreas, incluindo a engenharia aeroespacial 5, exploração de alto mar 6, 7, 8 de armazenamento de hidrogénio, 9, etc. No entanto, eles ainda demonstrar algumas desvantagens, tais como a baixa resistência. Além disso, a luz infravermelha é capaz de transmitir através HGM e aquecer o objecto atrás. mesmose, modificações de superfície sobre HGM são essenciais para reduzir a transferência térmica radiativa. Um método eficaz consiste em revestir um material de bloqueio de IR para a superfície de HGM. Como um semicondutor, TiO 2 tem sido usados em muitas áreas, tais como foto-catálise 12, 13, desenvolvimento de células solares, fabrico de sensores 14, 15 aplicações ambientais, e de armazenamento de energia 16. Além disso, ele também mostra baixa emissividade à luz visível e infravermelha de banda 17, 18, 19. Portanto, para os nossos propósitos, TiO 2 foi uma seleção prudente devido ao seu preço relativamente baixo e alto desempenho. No entanto, o revestimento é muito fácil para os poluentes para sujar, o que afeta seriamente a refletividade do TiO 2. A refletividade deve reduzir gradualmente. Portanto, um self-limpeza do revestimento é essencial para evitar que o revestimento de incrustação e para prolongar o tempo de trabalho de um tal revestimento. Neste texto, um método-química suave foi usada para desenvolver hidrofóbicas TiO2 -Revestido HGM. Titanato de tetrabutilo (TBT) e 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PFOTES) foram seleccionados como a fonte de Ti e agente de super-hidrófobos, respectivamente. Eles foram hidrolisados ​​e depositado sobre a superfície de HGM. Em seguida, depois de o processo hidrotermal, a anatase TiO2 formado na superfície do HGM, e as propriedades hidrofóbicas permaneceu. Para comparação, PFOTES HGM-revestido único (F-SCHGM) e de TiO 2 HGM-revestido único (Ti-SCHGM) foram sintetizados como bem. O esquema de síntese é mostrado na 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 propõe um método-química suave para desenvolver microesferas de vidro ocas e hidrofóbicas altamente IR-reflectoras (HGM). A anatase TiO2 e um agente de super-hidrófobos foram revestidos sobre a superfície de HGM em um passo. TBT e PFOTES foram seleccionados como a fonte de Ti e o agente de super-hidrófobos, respectivamente. Eles foram ambos revestidos no HGM, e após o processo hidrotermal, o TBT se virou para anatase TiO2. Desta forma, um PFOTES / TiO 2 -Revestido HGM (MCHGM) foi preparado. Para comparação, PFOTES HGM-revestido único (F-SCHGM) e de TiO 2 HGM-revestido único (Ti-SCHGM) foram sintetizados como bem. Os PFOTES e TiO 2 revestimentos na superfície de HGM foram demonstrados por meio de difracção de raios-X (DRX), microscopia electrónica de varrimento (SEM), e caracterizações detector de dispersão de energia (EDS). O MCHGM mostraram um maior ângulo de contacto (153 °), mas um menor ângulo de deslizamento (16 °) do que o F-SCHGM, com um ângulo de contacto de 141,26; e um ângulo de 67 ° de deslizamento. Além disso, tanto Ti-SCHGM e MCHGM apresentado valores de reflectividade IV semelhantes, que eram de cerca de 5,8% mais elevada do que a HGM original e F-SCHGM. Além disso, o revestimento PFOTES pouco mudou a condutividade térmica. Portanto, F-SCHGM, com uma condutividade térmica de 0,0479 W / (m.K), foi bastante como o HGM original, que foi 0,0475 W / (mK). MCHGM e Ti-SCHGM também foram semelhantes. Os seus valores de condutividade térmica foram 0,0543 W / (mK) e 0,0543 W / (m.K), respectivamente. O revestimento de TiO2 aumentou ligeiramente a condutividade térmica, mas com o aumento da reflectividade, a propriedade de isolamento térmico global-se reforçada. Finalmente, uma vez que a propriedade de reflexão de IR é fornecido pelo revestimento HGM, se o revestimento for derrubado, a ref lectividade diminui. Portanto, com o revestimento hidrofóbicas, a superfície é protegido de incrustao, e também a sua vida útil é prolongada.

Os testes na etapa 4.4 revelam muitas características e propriedades das amostras. O XRD (Figura 2) reflecte a formação de anatase TiO2. O SEM (Figura 3) e a EDS (Figura 4) exibir o TiO 2 e PFOTES que são revestidos sobre a superfície de HGM. O ângulo de contacto (Figura 5) e o ângulo de deslizamento (Figura 6) Os testes representam o superhydrophobicity. O teste de transmit?...

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</subMicroesferas de vidro ocas&gt; -Revestido com propriedades super-hidrofóbicas e alta IR-reflexivo sintetizados por um método Soft-química

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 visualizações.  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.

Vídeo: 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.

Fabricação de Sílica Ultra microresonators alto fator de qualidade

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

Engenharia

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.

Captação de energia solar por meio da carga de separação de nanocristais e seus 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.

Síntese e Caracterização de Supramoleculares Colloids

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.

Fabricação de Microsferas de Polímeros para Resonadores Ópticos e Aplicações Laser

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.

Sintetizando o tungstato de sódio e microcápsulas de molibdato de sódio através da excreção bacteriana de minerais

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.

Fabricação de superfícies de Metal Superhydrophobic para aplicações antigelo

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 e células em Aqueous Ambiente Usando TiO<sub&gt; 2</sub&gt; Photocatalysis

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

Bioengenharia

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.

Um método sintético Facile para obter Oxyiodide de bismuto microesferas altamente funcional para os processos de Photocatalytic de depuração de água

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.

Renderização SiO2/Si Surfaces Omniphobic esculpindo microtexturas de armadilha de gás compreendendo reentrant e duplamente reentrant cavidades ou pilares

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.

Monólitos de Microhoneycomb preparados pela liofilização unidirecional de nanofibras de celulose com base Sols: método e extensões

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

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