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Silsesquioxanes and Silica Nanoparticles as Platforms for Fluorine and Gadolinium Based Contrast Agents for Magnetic Resonance Imaging; Silsesquioxane und Silika-Nanopartikel als Grundlagen für Fluor- und Gadolinium-basierte Kontrastmittel für die Magnetresonanz-Bildgebung

Kocak, Filiz
Fonte: Universität Tübingen Publicador: Universität Tübingen
Tipo: Dissertação
EN
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Magnetic resonance imaging (MRI) is an important diagnostic tool for the imaging of soft tissues. The non-invasive technique of MRI allows for the detection of tumors, infections and injuries at an early stage. New opportunities for medical diagnosis and magnetic resonance (MR) imaging techniques are offered with the use of hybrid nanomaterials. The functionalization of a nano-sized material, e.g. with paramagnetic Gd(III) chelate complexes for 1H imaging or with 19F containing molecules for 19F imaging leads to a high concentration of contrast agents, which can be obtained at low volumes. In the first part of the work T8-silsesquioxanes were functionalized with polyorganofluorinated groups (PFG). By different synthetic pathways highly symmetrical polyorganofluorinated POSS cubes (PF-POSS) which generate a sharp singlet in the 19F spectrum were obtained. The properties of the PF-POSS cubes in dependency of their PFG structures, the resulting solubility and their hydrolysis stability were investigated. Additionally, in vitro measurements as well as post mortem experiments were performed for chosen examples. In the second part of this work the size dependent properties of spherical and monodisperse silica nanoparticles (SNPs) with diameters of about 15...

Adhesion enhancement of powder coatings on galvanised steel by addition of organo-modified silica particles

Puig, M.; Cabedo, L.; Gracenea, J.J.; Jiménez Morales, Antonia; Gámez-Pérez, J.; Suay, J.J.
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/acceptedVersion; info:eu-repo/semantics/article
Publicado em /08/2014 ENG
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The addition of organo-modified silica particles (OSP) to organic monolayer coatings has been investi-gated as an alternative to the use of primers or surface pretreatments in galvanised steel substrates. Acommercial additive consisting of trifunctional organosilane (alkyl-triethoxysilane) grafted on silica par-ticles was directly incorporated at different concentrations (1, 2.5, 3.5 and 4.5 wt%) as an integral additivein a polyester powder coating. The OSP were characterised physicochemically by means of FTIR and TGA,and the coating formulated by DSC. The anticorrosive properties of the systems were evaluated by meansof electrochemical impedance spectroscopy (EIS), showing improvements with all the formulations con-taining the OSP, especially in the coating with 2.5% OSP. In order to explain this behaviour, morphological(using SEM) and adhesion studies were done. The formation of agglomerates in the powder coatings wasdetected when the concentration was over 2.5%. There was an improvement in the adhesion of the coat-ing to the substrate for all the samples containing the OSP but especially for that containing 2.5%. Theimpact resistance was increased too, especially in the formulations with 2.5% and 3.5%.; This work has been financially supported by the Spanish Ministry of the Economy and Competitiveness and the ERDF (Project IPT-020000-2010-1).

Effect of cryoprotectants on the reconstitution of silica nanoparticles produced by sol-gel technology

Andreani, Tatiana; Kiill, Charlene Priscila; Souza, Ana Luiza R. de; Fangueiro, Joana F.; Doktorovova, Slavomira; Garcia, Maria L.; Gramiao, Maria Palmira Daflon; Silva, Amelia M.; Souto, Eliana B.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 1001-1007
ENG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Freeze-drying has widely been applied to improve the stabilization of colloidal drug carriers. In the present study, the effect of cryoprotectants on the physicochemical characteristics of silica nanoparticles (SiNP) during the freeze-drying process has been extensively investigated. SiNP were synthesized by sol-gel technology and freeze-dried in the presence of sorbitol, trehalose, and/or mannitol at different concentrations and ratios. Dynamic light scattering (DLS), atomic force microscopy (AFM), X-ray diffraction analysis (XRD), and differential scanning calorimetry (DSC) have been used for particle characterization after freeze-drying. Based on the obtained results, SiNP in the presence of mannitol showed a more crystalline behavior in comparison to nanoparticles with sorbitol or trehalose (confirmed by DSC and XRD). SiNP in the presence of trehalose showed a more crystalline structure than SiNP in the presence of sorbitol. However, trehalose was more efficient in preserving the particle size of nanoparticles during the freeze-drying process. The optimal concentration of trehalose for preserving silica nanoparticles was 10 % at a ratio of (1:1). During the freeze-drying process...

Simulation of Vickers indentation of silica glass

JEBAHI, Mohamed; ANDRÉ, Damien; DAU, Frédéric; CHARLES, Jean-Luc; IORDANOFF, Ivan
Fonte: Elsevier Publicador: Elsevier
EN
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The indentation response of glasses can be classified under three headings: normal, anomalous and intermediate, depending on the deformation mechanism and the cracking response. Silica glass, as a typical anomalous glass, deforms primarily by densification and has a strong tendency to form cone cracks that can accompany median, radial and lateral cracks when indented with a Vickers tip. This is due to its propensity to deform elastically by resisting plastic flow. Several investigations of this anomalous behavior can be found in the literature. The present paper serves to corroborate these results numerically using the discrete element method. A new pressure-densification model is developed in this work that allows for a quantitative estimate of the densification under very high pressure. This model is applied to simulate the Vickers indentation response of silica glass under various indentation forces using the discrete element method first, and then a discrete–continuum coupling method with large simulation domains to suppress the side effects and reduce the computational time. This coupling involves the discrete element method (DEM) and the constrained natural element method (CNEM). The numerical results obtained in this work compare favorably with past experimental results.

Silica-based Nano-coating on Zirconia Surfaces Using Reactive Magnetron Sputtering: Effect on Chemical Adhesion of Resin Cements

Cavalcanti Queiroz, Jose Renato; Massi, Marcos; Nogueira, Lafayette; Silva Sobrinho, Argemiro Soares da; Bottino, Marco Antonio; Oezcan, Mutlu
Fonte: Quintessence Publishing Co Inc Publicador: Quintessence Publishing Co Inc
Tipo: Artigo de Revista Científica Formato: 151-159
ENG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 09/53584-4; Purpose: To compare the effect of silica (Si)-based nano-coating deposited by reactive magnetron sputtering (RMP) with that of conventional surface conditioning using metal/zirconia primer alone or after air-particle abrasion on the adhesion of resin cements to zirconia ceramic.Materials and Methods: Two hundred forty zirconia ceramic blocks (Cercon) were sintered, finished with 1200-grit SiC paper under water cooling, and cleaned ultrasonically in distilled water for 10 min. The blocks (4.5 mm x 3.5 mm x 4.5 mm) were randomly divided into 24 groups (n = 10) according to 3 testing parameters: a) resin cements (Multilink, Panavia F, RelyX U100), b) surface conditioning (no conditioning as control group; Metal/Zirconia Primer; air abrasion + Metal/Zirconia Primer; Si-based nanofilm + Monobond s); c) aging (no aging vs thermo cycling at 5 degrees C to 55 degrees C, 6000 cycles). The nanofilm was deposited by direct current using argon/oxygen plasma (8:1 in flux) on the zirconia surface. Resin cements were bonded to zirconia surfaces using polyethylene molds. The shear bond strength (SBS) test was performed using a universal testing machine (1 mm/min)...

Estudos voltametricos de eletrodos quimicamente modificados a base de pasta de carbono e silica gel funicionalizada para determinação de cobre e prata

Keila Schutzer Mendes Ferreira
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 24/05/2000 PT
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Um eletrodo quimicamente modificado à base de pasta de carbono e sílica gel funcionalizada com 3 (2-tiobenzimidazolil) propila (EPCQM) está sendo usado na pré-concentração e na determinação de Cu e Ag por voltametria de pulso diferencial com velocidade de varredura 5 mV s e a amplitude de pulso para o Cu é 50 mV e para a Ag100 mV. O estudo foi feito em meio aquoso em KCSN, KCl e KNO3 0,01 mol L, onde.o Cu e a Ag são pré-concentrados no eletrodo sem aplicação de potencial. Verificou-se que a adsorção na superfície do eletrodo depende do pH das soluções, do tempo, da solução utilizada na pré-concentração, composição da pasta e de outras variáveis. A pré-concentração foi realizada em solução de 20,00 mL de HNO3 1,00x10 mol L (pH = 5,0) e a varredura de potencial de -0,4 V a 0,6 V para o Cu e -0,2 V. a 0,3 V para a Ag (varredura anódica). A irreversibilidade do processo do eletrodo foi verificado pelo deslocamento ou pela ausência da onda catódica quando utilizada a voltametria cíclica. Os resultados obtidos indicam a aplicabilidade do método na faixa de concentração para o cobre de 2,74x10 mol L a 1,89x10 mol L e para a prata 2,74x10 mol L a 1,09x10 mol L, onde obteve uma linearidade, com 5 minutos de pré-concentração...

Modificação estrutural em silica vitrea e quartzo cristalino por implantação de He+ para guiamento optico

Christiano Pereira Guerra
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/10/1996 PT
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O propósito deste trabalho foi estudar a aplicação da técnica de implantação de íons para a modificação de índice de refração em substratos vítreos e cristalinos, possibilitando o guiamento óptico. Foram implantados íons de HE + com energia variando entre 30 e 190 KeV e doses entre 1,0x10 16 e 2,5x10 16 íons/cm 2 em lâminas de sílica vítrea e quartzo cristalino com cortes perpendiculares aos eixos x, y, e z. Para a caracterização óptica foram feitas medidas dos modos de propagação TE (transversal elétrico) e TM (transversal magnético) de um feixe laser AR + sintonizado em λ 488,0 nm, através do método 'dark modes'. Foram estudados os efeitos da variação de dose, energia e recozimento nos modos propagantes na camada modificada. Foram utilizados diferentes técnicas de espectroscopia infravermelho para analisar as modificações estruturais dos silicatos pelo bombardeamento dos íons de hélio. Análises por difração de raio-X também foram utilizadas para analisar a estrutura do cristal de quartzo puro e modificado pela implantação dos íons.; The purpose of this work was to study the technical application of íon implantation to modify the refraction index on vitreous and crystallines substrates...

Sílice: el aliado oculto y estratégico para el desarrollo empresarial de la industria nacional; Silica: the hidden and strategic partner for business development of national industry

Cahuana Mojica, Alexandra Ximena; Ortiz Riaga, Carolina
Fonte: Universidad Militar Nueva Granada; Facultad de Ciencias Económicas; Especialización en Alta Gerencia Publicador: Universidad Militar Nueva Granada; Facultad de Ciencias Económicas; Especialización en Alta Gerencia
Tipo: bachelorThesis; Trabajo de grado Formato: pdf; pdf
SPA
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Colombia es un territorio rico en diversos recursos naturales no renovables ejemplo de ello él sílice, ya que sirve para la elaboración de diferentes materiales; sin embrago, en la actualidad la explotación de este mineral no es eficiente y no existen cifras exactas, esto debido a la baja tecnificación (exploración artesanal e ilegal), la falta de una normatividad clara, y de una formación tecnológica para llevar a cabo el proceso de explotación del mineral; es por ello que se deben formar altos gerentes que adquieran conocimientos en estas áreas y así superar estas problemáticas y liderar un verdadero desarrollo en la industria minera nacional. Es necesario abrir fronteras financieras para el mayor aprovechamiento de este mineral, creando alianzas estratégicas con países del continente asiático como china los cuales poseen tecnologías y equipos tecnificados que permitan la explotación del mineral sílice, volviéndolo una prioridad en su economía por los productos que ellos elaboran, y comercializan en todo el mundo.; Colombia is a territory rich in various non-renewable natural resources such example silica him, as it serves to prepare different materials; no clutch, currently exploiting this mineral is not efficient and there are no exact figures...

Preparação e caracterização de compósitos poliméricos baseados em amido termoplástico e materiais de alta área superficial: zeólita ZSM-5 e sílica coloidal

Plotegher,Fábio; Ribeiro,Caue
Fonte: Associação Brasileira de Polímeros Publicador: Associação Brasileira de Polímeros
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 PT
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Foram produzidas amostras de amido termoplástico (TPS) reforçadas com materiais de alta área superficial, com o intuito de verificar a variação nas propriedades do polímero, com especial enfoque na sua permeabilidade a vapor d'água. Foram utilizadas como carga a sílica coloidal (área superficial de 122,7 m²/g) e uma zeólita do tipo ZSM-5, produzida em laboratório (área superficial de 261,3 m²/g), em teores de 2 a 10% em massa. Os resultados demonstraram que a adição de ambos os materiais melhorou as propriedades mecânicas do TPS, embora nos maiores teores houve redução da qualidade das interfaces e dessas propriedades, principalmente para a ZSM-5. Em todos os casos a introdução da carga inorgânica reduziu a permeabilidade ao vapor d'água em até 20% quando comparada à permeabilidade do TPS, porém a melhor dispersão da sílica coloidal na matriz permitiu as maiores reduções, apesar da área superficial inferior.

Characterisation of chalcogenide 2D photonic crystal waveguides and nanocavities using silica fibre nanowires

Smith, Cameron L C; Grillet, Christian; Tomiljenovic-Hanic, Snjezana; Magi, Eric; Moss, D J; Eggleton, Benjamin J; Freeman, Darren; Madden, Steve; Luther-Davies, Barry
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
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We describe the fabrication of low-loss, highly flexible silica fibre nanowires which are used to characterise chalcogenide two-dimensional photonic crystal waveguide circuits and nanocavities. Localised coupling is achieved in good agreement with theory.

Photoluminescence from Si Nanocrystals ini Silica: The Effect of Hydrogen

Cheylan, S; Elliman, Robert
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
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The effect of H passivation on the PL emission of Si nanocrystals produced in silica by ion-implantion and annealing is shown to depend on the implant fluence. At low fluences, where the nanocrystals are small, passivation causes an enhancement of the emi

Optical emission from erbium-doped silica nanowires

Elliman, Robert; Wilkinson, Andrew; Kim, Tae-Hyun; Sekhar, P; Bhansali, Shekhar
Fonte: American Institute of Physics (AIP) Publicador: American Institute of Physics (AIP)
Tipo: Artigo de Revista Científica
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Infrared optical emission from erbium-doped silica nanowires is shown to have property characteristic of the material nanostructure and to provide the basis for the fabrication of integrated photonic devices and biosensors. Silica nanowires of approximate

Silica nanoparticles as dexamethasone delivery systems able to induce the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells

Amorim, Sara; Martins, A.; Neves, N. M.; Pires, R. A.; Reis, R. L.
Fonte: John Wiley & Sons, Ltd Publicador: John Wiley & Sons, Ltd
Tipo: Conferência ou Objeto de Conferência
Publicado em /12/2013 ENG
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Bioactive glasses, especially silica-based materials, are reported to pres- ent osteoconductive and osteoinductive properties, fundamental char- acteristics in bone regeneration [1,2]. Additionally, dexamethasone (Dex) is one of the bioactive agents able to induce the osteogenic differ- entiation of mesenchymal stem cells by increasing the alkaline phos- phatase activity, and the expression levels of Osteocalcin and Bone Sialoprotein [3]. Herein, we synthesised silica (SiO2) nanoparticles (that present inherent bioactivity and ability to act as a sustained drug delivery system), and coated their surface using poly-L-lysine (PLL) and hyaluronic acid (HA) using the layer-by-layer processing technique. Further on, we studied the influence of these new SiO2-polyelectrolyte coated nanoparticles as Dex sustained delivery systems. The SiO2 nanoparticles were loaded with Dex (SiO2-Dex) and coated with PLL and HA (SiO2-Dex-PLL-HA). Their Dex release profile was evaluated and a more sustained release was obtained with the SiO2-Dex-PLL-HA. All the particles were cultured with human bone marrow-derived mes- enchymal stem cells (hBMSCs) under osteogenic differentiation culture conditions. hBMSCs adhered, proliferated and differentiated towards the osteogenic lineage in the presence of SiO2 (DLS 174nm)...

Templated synthesis of high surface area inorganic oxides by silica aquagel-confined co-precipitation

Marbán Calzón, Gregorio; Fuertes Arias, Antonio Benito; Valdés-Solís Iglesias, Teresa
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 22195 bytes; application/pdf
ENG
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8 pages, 7 figures, 2 tables. -- Available online 10 October 2007.; A new and simple synthetic strategy for the preparation of high surface area nanosized metallic oxides using low cost precursors is described in this work. It is based on the coagulation – precipitation processes that occur when the metallic cations of salts dissolved in a silica aquagel medium are forced to precipitate by means of basic reagents. Nanoparticulate aggregates of the metallic oxides can then be obtained by applying the subsequent steps of drying, calcination and silica removal. Here, we illustrate the application of this technique by the preparation of both single and mixed metallic oxides such as copper oxide/ceria, hematite, cobalt ferrite and copper manganese spinel. The materials obtained in this way are made up by aggregates of nanosized particles (2–8 nm) and they exhibit very high surface areas up to 300 m2/g. Depending on the chemical composition of the oxides, different structures ranging from quasi-rounded nanoparticles to aggregates of needle-shaped nanoparticles were obtained.; Funding by Spanish National Project MAT2005-00262 and FICYT Regional Project (IB05-001) is acknowledged. T.V.S. acknowledges the CSIC-ESF for the award of an I3P postdoctoral contract.; Peer reviewed

Multi-point immobilization of Penicillin G Acylase on Silica-Glioxyl: Influence of the degree of activation

Pereira, G. H. A.; Guisán, José Manuel; Giordano, R. L. C.
Fonte: Associação Brasileira de Engenharia Química Publicador: Associação Brasileira de Engenharia Química
Tipo: Artículo
ENG
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Multi-point immobilization, by an intense enzyme-support attachment, may increase the operational stability of a biocatalyst. Penicillin G acylase has many applications, from the hydrolysis of penicillin G (production of 6-aminopenicillanic acid) to the synthesis of semi-synthetic antibiotics. The application of this technique in macroporous silica involves support activation with 3-glycidyloxypropyltrimetoxysilane, followed by acidic hydrolysis and oxidation with sodium periodate. The aldehyde-glyoxyl groups so formed react subsequently with the enzyme. The degree of activation affects the yield and stability of the enzyme immobilization. For 20 UI of enzyme, the results show an immobilization yield equal to 100%, whenever there are more than 140 m Eq of aldehyde groups/g of dry silica. The immobilized enzyme half-life is 23 minutes at 60ºC; under the same conditions, the soluble enzyme has no residual activity after a few minutes. The increase in the degree of activation does not lead to higher stability, which indicates the negative influence of sub-products, formed during the activation of the support.; This work has been supported by PADCT/CNPq and CNPq/RHAE; Peer reviewed

Sulphatic characterization of rice husk ashes. Comparative study with the Spanish silica fume

Talero Morales, Rafael; Pedrajas, C.; Delgado, A.; Rahhal, V.
Fonte: Conselho Superior de Investigações Científicas Publicador: Conselho Superior de Investigações Científicas
Tipo: Comunicación de congreso Formato: 154573 bytes; application/pdf
ENG
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En: 1st Spanish National Conference on Advances in Materials Recycling and Eco – Energy Madrid, 12-13 November 2009.-- Editors: F. A. López, F. Puertas, F. J. Alguacil and A. Guerrero.-- 4 pages, 3 tables.; In this investigation it has determinated the "chemical character" by sulphatic characterization of two industrial incinerated residues, ashes C1 and C2, in order to incorporate them as puzzolanic addition, in the manufacture of cements, traditional or high resistance concretes and mortars. Also, It was considered carry out a comparative study with the Spanish silica fume, HS. Then, experimental results showed that the two ashes, can be considerate as artificial puzzolanic additions with silicic "chemical character", but only one of them that of major content of SiO2, C2, could become considerate as “microsilica On the other hand, C1 couldn´t be considerated, because the content of P.F. resulted too high, although the content of reactive silica, SiO2r- was bigger than de content of C2. For this motive, the C1 ash was refused for this propose, in spite of in the sulphatic characterization it showed a more near conduct to HS.; Peer reviewed

Estudio por difracción de rayos X de la hidratación de mezclas de CaAl2O4 - Humo de silice; In situ X-ray difraction study of hidration of CaAl2O4 - amorphous silica mixtures

Rivas-Mercury, J. M.; Turrillas, Xavier; Aza Moya, Antonio H. de; Rodríguez Barbero, Miguel Ángel; Peña, P.
Fonte: Sociedad Española de Cerámica y Vidrio Publicador: Sociedad Española de Cerámica y Vidrio
Tipo: Artículo Formato: 1854340 bytes; application/pdf
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[ES] Se ha estudiado la influencia del humo de sílice sobre el mecanismo de hidratación del monoaluminato de calcio (CaAl2O4) a temperatura ambiente y con una relación agua/sólidos de 0,5. La evolución de las fases hidratadas, que se forman en los primeros instantes de la reacción, se ha estudiado por difracción de rayos X de laboratorio con una resolución temporal de 36 min. La integración de picos de difracción seleccionados de las fases: Ca2Al2O5·8H2O (Ca2Al2(OH)10·3H2O), CaAl2O4 y Ca4Al2(OH)12(CO3)·5H2O, ha permitido establecer la cinética de la reacción. Así, se ha puesto de manifiesto que el humo de sílice provoca una drástica disminución en el periodo de inducción de la hidratación y acelera la formación de los hidratos cristalinos metaestables Ca2Al2(OH)10·3H2O y Ca4Al2(OH)12(CO3)·5H2O. Estos resultados se han confirmado por Termogravimetría, Análisis Térmico Diferencial y Microscopía Electrónica de Barrido. El mecanismo de hidratación propuesto se apoya en datos previos de Resonancia Magnética Nuclear de Sólidos (RMN) de 29Si de los autores de este articulo.; [EN] The influence of the amorphous silica on the mechanism of hydration of the calcium monoaluminate (CaAl2O4) has been studied at ambient temperature with a water/solids ratio of 0.5. The evolution of the hydrated phases...

Phase behavior and preparation of mesoporous silica in aqueous mixtures of fluorinated surfactant and hydrophobic fluorinated polymer

Sharma, Suraj Chandra; Kunieda, Hironobu; Esquena, Jordi; Rodríguez Abreu, Carlos
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 19968 bytes; application/msword
ENG
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8 pages, 10 figures.; The phase behavior and formation of self-assemblies in the ternary water/fluorinated surfactant (C8F17EO10)/hydrophobic fluorinated polymer (C3F6O)nCOOH system and the application of those assemblies in the preparation of mesostructured silica have been investigated by means of phase study, small angle X-ray scattering, and rheology. Hexagonal (H1), bicontinuous cubic (V1) with Ia3d symmetry, and polymer rich lamellar () are observed in the ternary diagram. C8F17EO10 molecules are dissolved in polymer rich aggregates, whereas (C3F6O)nCOOH molecules are practically insoluble in the surfactant lamellar phase due to packing restrictions. Hence, two types of lamellar phases exist: one with surfactant rich (Lα) and the other with polymer rich () in the water/C8F17EO10/(C3F6O)nCOOH system. As suggested by rheological measurements, worm-like micelles are present in C8F17EO10 aqueous solutions but a rod-sphere transition takes place by solubilization of (C3F6O)nCOOH. C8F17EO10 acts as a structure directing agent for the preparation of hexagonal mesoporous silica by the precipitation method. The addition of (C3F6O)nCOOH induces the formation of larger but disordered pores.; We dedicate this paper to the memory of our dear Prof. Hironobu Kunieda who recently passed away. This work was supported by CREST of JST (Japan Science and Technology Corporation). C.R. is grateful to the Japan Society for the Promotion of Science (JSPS) for a research grant. We acknowledge Prof. J. Tatami and Dr. T. Wakihara of Yokohama National University for their help in the adsorption measurements...

Double fitting of Maker fringes to characterize near-surface and bulk second-order nonlinearities in poled silica

Qiu, Mingxin; Vilaseca, Ramon; Botey, Muriel; Sellarès, Jordi; Pi, F.; Orriols Tubella, Gaspar
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2000 ENG
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An experimental analysis of the distribution and thickness of the bulk nonlinearity induced in poled silica is reported. The second-order susceptibility decreases exponentially from the anodic interface. Maker fringe patterns showing a double structure are interpreted in relation to the presence of two nonlinear profiles, one concentrated near the anodic surface and another extending into the bulk of the sample. The Maker fringe theory is properly generalized and a double fitting technique reproducing well the experimental results is used to characterize the induced nonlinearities. The dependence of the second-harmonic signal on the poling temperature is given, which is different from that of sol-gel silica.

Applications of femtosecond laser induced self-organized planar nanocracks inside fused silica glass

Taylor, Rod; Hnatovsky, Kyrylo (Cyril); Simova, Eli
Fonte: Wiley-VCH Verlag GMBH Publicador: Wiley-VCH Verlag GMBH
Tipo: Artigo de Revista Científica
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We review our recent experimental efforts towards developing photonic and biophotonic applications of femtosecond laser induced self-organized planar nanocracks inside fused silica glass. Our results show that sub-diffraction limited, periodic, plrar cracks can be produced, organized, erased and rewritten and basically controlled inside fused silica glass where they can be diagnosed optically using form birefringence. The high degree of control over these self-replicated periodic structures Aows us to investigate applications in micro- and nanofluidics, porous capillaries for biofiltefing and rewritable data storage for harsh environments. Optical birefringence measurement of a grating voxel. A figure is presented.