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Montmorillonite as a component of polysulfone nanocomposite membranes

ANADAO, Priscila; SATO, Lais Fumie; Wiebeck, Helio; VALENZUELA-DIAZ, Francisco Rolando
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
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Nanocomposite membranes containing polysulfone (PSI) and sodium montmorillonite from Wyoming (MMT) were prepared by a combination of solution dispersion and the immersion step of the wet-phase inversion method. The purpose was to study the MMT addition with contents of 0.5 and 3.0 mass% MMT in the preparation of nanocomposite membranes by means of morphology, thermal, mechanical and hydrophilic properties of nanocomposite membranes and to compare these properties to the pure PSf membrane ones. Small-angle X-ray diffraction patterns revealed the formation of intercalated clay mineral layers in the PSf matrix and TEM images also presented an exfoliated structure. A good dispersion of the clay mineral particles was detected by SEM images. Tensile tests showed that both elongation at break and tensile strength of the nanocomposites were improved in comparison to the pristine PSf. The thermal stability of the nanocomposite membranes, evaluated by onset and final temperatures of degradation, was also enhanced. The hydrophilicity of the nanocomposite membranes, determined by water contact angle measurements, was higher; therefore, the MMT addition was useful to produce more hydrophilic membranes. (C) 2009 Elsevier B.V. All rights reserved.; Fapesp

Nanocompósitos de elastômero SBR e argilas organofílicas.; Nanocomposite of SBR elastomer and organophillic clays.

Guimarães, Thiago Ribeiro
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 26/03/2008 PT
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Compósitos são materiais híbridos que resultam de associações de, pelo menos, dois tipos deferentes de materiais. O desenvolvimento da sociedade humana somente atingiu o estágio atual utilizando-se de compósitos de todo o tipo de misturas de materiais. Além disso, o desenvolvimento de compósitos com partículas cada vez menores de fase reforçante com o passar das décadas, ou precisamente, dos séculos foram as principais razões do alcance do "estado da arte" da ciência dos compósitos. Com relação à ciência dos compósitos, os nanocompósitos são a grande descoberta do último meio século. Seguindo tendências dos estudos na área dos compósitos, este trabalho foca obter nanocompósitos de elastômero SBR (matriz elastomérica) com argilas tratadas e não tratadas. Além disso, a avaliação de propriedades mecânicas, térmicas, reológicas, de cura, em solução e propriedades de difração de raios-X são outro alvo deste trabalho. Os compósitos foram preparados com equipamentos tradicionais de processamento de elastômeros e, depois disso, suas propriedades foram avaliadas. Considerando propriedades em difração de raios-X, somente o compósito com Cloisite 20A mostrou estrutura intercalada. Os compósitos com argilas tratadas mostraram um melhor perfil geral de propriedades...

Estudo das propriedades mecânicas, reológicas e térmicas de nanocompósito de HMSPP (polipropileno com alta resistência do fundido) com uma bentonita Brasileira; Study of mechanical, rheological and thermal properties of nanocomposite HMSPP (high melt strength polypropylene) with a brazilian bentonite

Fermino, Danilo Marin
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 22/06/2011 PT
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Este trabalho aborda o estudo do comportamento mecânico, térmico e reológico do nanocompósito de HMSPP polipropileno de alta resistência do fundido (obtido por radiação gama na dose de 12,5 kGy) e uma argila brasileira bentonítica do Estado da Paraíba (PB), conhecida como chocolate com concentração de 5 e 10 % em massa em comparação a uma argila americana, Cloisite 20A. Foi utilizado nesse nanocompósito o agente compatibilizante polipropileno graftizado com anidrido maleico PP-g-AM com 3 % de concentração em massa, através da técnica de intercalação do fundido utilizando uma extrusora de dupla-rosca e, em seguida, os corpos de prova foram confeccionados em uma injetora. O comportamento mecânico foi avaliado pelos ensaios de tração, flexão e impacto. O comportamento térmico foi avaliado pelas técnicas de calorimetria exploratória diferencial (DSC) e termogravimetria (TGA). O comportamento reológico foi avaliado em um reômetro de placas paralelas. A morfologia dos nanocompósitos foi estudada pela técnica de microscopia eletrônica de varredura (MEV). As bentonitas organofílicas e os nanocompósitos foram caracterizados por difração de raios X (DRX) e infravermelho (FTIR). Nos ensaios mecânicos houve um aumento de 9 % na resistência à tração e no módulo de Young...

O estudo do comportamento reológico de nanocompósitos de copolímeros em bloco contendo nanocargas.; Study of nanocomposite rheological behavior of block copolymers containing nanofiller.

Amurin, Leice Gonçalves
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/02/2014 PT
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Neste presente trabalho foi realizado um estudo sobre copolímeros em bloco e seus nanocompósitos com diferentes estruturas morfológicas. Os polímeros estudados foram copolímeros de poliestireno-b-poli(etileno-co-butileno)-b-poliestireno (SEBS), sendo dois desses copolímeros com fração em massa de 30% de blocos de poliestireno (PS), e um deles modificado com anidrido maleico na fase de poli(etileno-co-butileno) (PEB). Os outros três copolímeros têm 13% de blocos de PS. A nanopartícula utilizada foi a argila montmorilonita organofílica Cloisite 20A. Os nanocompósitos foram preparados por dois métodos: i) mistura no estado fundido (extrusão); ii) solução. As microestruturas dos materiais resultantes foram caracterizadas pelas técnicas de espalhamento de raios X a baixo ângulo (SAXS) e difração de raios-X (DRX). As propriedades reológicas foram avaliadas em dois tipo de fluxo (cisalhamento e elongacional). Para avaliar as propriedades reológicas em fluxo de cisalhamento foram realizados ensaios de cisalhamento oscilatório em pequenas amplitudes (SAOS), cisalhamento oscilatório em grandes amplitudes (LAOS) e varredura de tempo (TS). Para avaliar as propriedades reológicas em fluxo elongacional foram realizados ensaios com geometria apropriada (SER)...

Silver Nanocomposite Electrode Modified with Hexacyanoferrate. Preparation, Characterization and Electrochemical Behaviour Towards Substituted Anilines

Fenga, Paula Goncalves; Stradiotto, Nelson Ramos; Isabel Pividori, Maria
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica Formato: 1100-1106
ENG
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); A novel conducting silver nanocomposite (nanoAg-GEC) material for electrochemical sensing of substituted anilines based on silver nanoparticles is presented. For the first time, the in situ growth of silver hexacyanoferrate nanoparticles (nanoAgHCF) on the surface of the silver nanocomposite electrodes was achieved. The surface morphology of the nanoAg-GEC electrode modified with hexacyanoferrate (nanoAgHCF-GEC) was investigated using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX). The electrochemical behaviour of the nanoAgHCF-GEC electrode towards oxidation and reduction of substituted anilines (procaine and sulfamerazine) was investigated by cyclic voltammetry. The results showed a linear dependence in the concentration range studied for each class of sulfonamides.

Desenvolvimento de materiais nanocompósitos e do processo de estereolitografia laser no infravermelho (CO2); Development of nanocomposite materials and the infrared laser stereolithography process

Maria Ingrid Rocha Barbosa
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 01/07/2010 PT
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A tendência atual na área de desenvolvimento de materiais aponta significantemente para o desenvolvimento de nanocompósitos. Várias pesquisas mostram que as características das propriedades que estes materiais apresentam ampliam de forma bastante promissora suas possíveis aplicações. Levando-se isso em consideração, este projeto tem como objetivo o estudo e desenvolvimento de materiais compósitos (polímero/carga) nanoestruturados para utilização no processo da Estereolitografia Laser no Infravermelho (CO2). Para tanto, o estudo envolve a mistura física de nanopartículas de sílica dispersas em uma matriz polimérica, composta por resina epóxi (diglicidil éter bisfenol A - DGEBA) e dietilenotriamina (DETA) como agente de cura. A determinação das propriedades térmicas e análise dos principais fenômenos e mecanismos gerais de cura do material nanocompósito foram realizadas utilizando a técnica de Calorimetria Exploratória Diferencial (DSC). Simulação computacional, utilizando um modelo matemático determinístico resolvido por volumes finitos através do programa ANSYS CFX®, foi realizada com o objetivo de avaliar os perfis da distribuição da temperatura espacial e temporal (análise térmica transiente)...

Development of marine-based nanocomposite scaffolds for biomedical applications

Reys, L. L.; Silva, S. S.; Boutinguiza, M.; Comesaña, R.; Lusquiños, F.; Pou, J.; Mano, J. F.; Silva, Tiago H.; Reis, R. L.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2012 ENG
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Despite the increasing attention that marine organisms are receiving, many of those are not efficiently exploited and subproducts with valuable compounds are being discarded. Two examples of those subproducts are the endoskeleton of squid, from which β-­‐chitin and consecutively chitosan can be obtained; and fish-­‐bones, as a source for the production of nano-­‐ hydroxyapatite. In this work, inspired in the nanocomposite structure of human bone, marine-­‐ based nanocomposite scaffolds composed by chitosan and nano-­‐hydroxyapatite (nHA) were developed using particle aggregation methodology. Chitosan was obtained from endoskeleton of giant squid Dosidicus Gigas while fish hydroxyapatite nanoparticles were synthesized from fish-­‐bones by pulsed laser in deionized water. An innovative methodology was used based on the agglomeration of prefabricated microspheres of chitosan/nHA, generally based on the random packing of microspheres with further aggregation by physical or thermal means to create a marine nanocomposite (CHA) .The morphological analysis of the developed nanocomposites revealed a low porosity structure...

Phosphorus removal by a fixed-bed hybrid polymer nanocomposite biofilm reactor

Oliveira, M.; Rodrigues, A. L.; Ribeiro, D. C.; Nogueira, R.; Machado, A. V.
Fonte: Taylor & Francis Publicador: Taylor & Francis
Tipo: Artigo de Revista Científica
Publicado em //2014 ENG
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Eutrophication is one of the main challenges regarding the ecological quality of surface waters, phosphorus bioavailability being its main driver. In this context, a novel hybrid polymer nanocomposite (HPN-Pr) biofilm reactor aimed at integrated chemical phosphorus adsorption and biological removal was conceived. The assays pointed to removal of 1.2 mg P/g of reactive phosphorus and 1.01 mg P/g of total phosphorus under steady-state conditions. A mathematical adsorption–biological model was applied to predict reactor performance, which indicated that biological activity has a positive effect on reactor performance, increasing the amount of reactive phosphorus removed.

Photocatalytic decomposition of phenol by nanocomposite of ZnS nanoparticles and montmorillonite

Praus,Petr; Matys,Jakub; Kozák,Ondřej
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2012 EN
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The nanocomposite of ZnS nanoparticles stabilized by cetyltrimethylammonium ions (ZnS-CTA) and montmorillonite (ZnS-CTA-MMT) was prepared and used as a catalyst for the photodecomposition of phenol under UV irradiation of a medium pressure Hg lamp. The content of ZnS in ZnS-CTA-MMT was about 7 wt.%. For comparison, the photodecomposition was also performed with ZnS-CTA, montmorillonite and with no catalyst, i.e., using only UV irradiation. The photodecomposition efficiency decreased in the order: UV + ZnS-CTA-MMT ≈ UV + ZnS-CTA > UV > UV + MMT. The photodecomposition in the presence of ZnS-CTA-MMT and ZnS-CTA proceeded according to the pseudo-first order reaction kinetics. In other cases, the photodecomposition corresponded to the pseudo-second order reaction of phenol and hydroxyl radicals. Hydroxyl radicals were produced by reactions of dissolved oxygen and electrons released from the ZnS nanoparticles and excited phenol molecules. MMT decreased the photodecomposition reaction rate and no MMT catalytic activity was observed.

Preconcentration and determination of organochlorine pesticides in seawater samples using polyaniline/polypyrrole-cellulose nanocomposite-based solid phase extraction and gas chromatography-electron capture detection

Mehdinia,Ali
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2014 EN
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In this work, the chemically modified filter paper with polyaniline/polypyrrole (PANI/PPY), denoted as PANI/PPY/cellulose nanocomposite, was prepared and used as the solid phase extraction (SPE) sorbent for preconcentration and extraction of some organochlorine pesticides (OCPs) in natural water samples. The proposed sorbent was also characterized with scanning electron microscopy (SEM) and exhibited that globular polymers could incorporate into the cellulose fibers of the paper sheet. Several experimental parameters related to the preconcentration of OCPs on the coated filter paper were also examined. The experimental results showed that the PANI/PPY coated filter paper could extract OCPs with relatively high enrichment factors. The evaluation also exhibited a dynamic range of 5-250 µg L-1 for OCPs with proper correlation coefficient (R²). The limit of detections of heptachlor, aldrin, dieldrin, endrin and 4-dichlorodiphenyltrichloroethane (4-DDT) were found to be 0.39, 0.28, 0.47, 0.51 and 0.31 µg L-1, respectively. The proposed method was also applied for analysis of OCPs in seawater sample and the recoveries of analytes were in the range of 77.4 to 102.7 %.

Nanocomposite polymer electrolytes based on poly(oxyethylene) and cellulose whiskers

Samir,My Ahmed Saïd Azizi; Alloin,Fannie; Sanchez,Jean-Yves; Dufresne,Alain
Fonte: Associação Brasileira de Polímeros Publicador: Associação Brasileira de Polímeros
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2005 EN
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Solid lithium-conducting nanocomposite polymer electrolytes based on poly(oxyethylene) (POE) were prepared from high aspect ratio cellulosic whiskers and lithium imide salt, LiTFSI. The cellulosic whiskers were extracted from tunicate -a sea animal- and consisted of slender parallelepiped rods that have an average length around 1 µm and a width close to 15 nm. High performance nanocomposite electrolytes were obtained. The filler provided a high reinforcing effect while a high level of ionic conductivity was retained with respect to unfilled polymer electrolytes. Cross-linking and plasticizing of the matrix as well as preparation of the composites from an organic medium were also investigated.

Preparation, characterization and gas permeation study of PSf/MgO nanocomposite membrane

Momeni,S. M.; Pakizeh,M.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2013 EN
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Nanocomposite membranes composed of polymer and inorganic nanoparticles are a novel method to enhance gas separation performance. In this study, membranes were fabricated from polysulfone (PSf) containing magnesium oxide (MgO) nanoparticles and gas permeation properties of the resulting membranes were investigated. Membranes were prepared by solution blending and phase inversion methods. Morphology of the membranes, void formations, MgO distribution and aggregates were observed by SEM analysis. Furthermore, thermal stability, residual solvent in the membrane film and structural ruination of membranes were analyzed by thermal gravimetric analysis (TGA). The effects of MgO nanoparticles on the glass transition temperature (Tg) of the prepared nanocomposites were studied by differential scanning calorimetry (DSC). The Tg of nanocomposite membranes increased with MgO loading. Fourier transform infrared (FTIR) spectra of nanocomposite membranes were analyzed to identify the variations of the bonds. The results obtained from gas permeation experiments with a constant pressure setup showed that adding MgO nanoparticles to the polymeric membrane structure increased the permeability of the membranes. At 30 wt% MgO loading, the CO2 permeability was enhanced from 25.75×10-16 to 47.12×10-16 mol.m/(m².s.Pa) and the CO2/CH4 selectivity decreased from 30.84 to 25.65 when compared with pure PSf. For H2...

Evaluation of PHB/Clay nanocomposite by spin-lattice relaxation time

Bruno,Mariana; Tavares,Maria Inês Bruno; Motta,Leandro Medeiros; Miguez,Eduardo; Preto,Monica; Fernandez,Amanda Oliveira Rodriguez
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
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Poly(3-hydroxybutyrate) (PHB) based on nanocomposites containing different amounts of a commercial organically modified clay (viscogel B7) were prepared employing solution intercalation method. Three solvents, such as: CHCl3, dimethylchloride (DMC) and tetrahydrofuran (THF) were used. The relationship among the processing conditions; molecular structure and intermolecular interaction, between both nanocomposite components, were investigated using a nuclear magnetic resonance (NMR), as a part of characterization methodology, which has been used by Tavares et al. It involves the hydrogen spin-lattice relaxation time, T1H, by solid state nuclear magnetic resonance, employing low field NMR. X ray diffraction was also employed because it is a conventional technique, generally used to obtain the first information on nanocomposite formation. Changes in PHB crystallinity were observed after the organophilic nanoclay had been incorporated in the polymer matrix. These changes, in the microstructure, were detected by the variation of hydrogen nuclear relaxation time values and by X ray, which showed an increase in the clay interlamelar space due to the intercalation of the polymer in the clay between lamellae. It was also observed, for both techniques...

Nanocomposite ZrC/a-C(:H) coatings for potential application onto biomedical implants

Escudeiro, Ana Isabel Costa
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Tese de Doutorado
ENG
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The release of particulate matter derived from biomedical implants has been considered determinant for their long-term survival. Polyethylene debris derived from polymer-on-metal coupling together with the metal ion release on metal-on-metal pairs appear to cause the most pronounced tissue reactions which may induce inflammatory reactions associated with the ultimate failure of the implant. The use of surface engineering, namely coating technology, offers an alternative approach in order to reduce the production of the wear debris. However, a critical feature for such an alternative technology is the adhesion of the coating on the metallic substrates after implantation and clinical use. This thesis deals with the synthesis and characterization of nanocomposite ZrC amorphous carbon (a-C) coatings with potential to improve the life time of biomedical implants. The coatings were deposited by dc magnetron sputtering in reactive (Ar+CH4) and non-reactive (Ar) atmosphere in order to produce hydrogenated and non-hydrogenated coatings, respectively. The first challenge to motivate this work was the need for high adhesion of the coatings. The critical loads (and thus adhesion) of the coatings has strongly increased with the application of a Ti/TiN/TiNC gradient layer between coating and substrate. Zr was incorporated into the C-matrix by varying the number of Zr pellets embedded in a graphite target. Different Zr contents...

Physical and electrochemical characterization of nanocomposite membranes of nafion and functionalized silicon oxide

Ladewig, Bradley; Knott, Robert; Hill, Anita; Riches, James; White, John; Martin, Darren James; da Costa, Joao; Lu, Gaoqing Max
Fonte: Royal Society of Chemistry Publicador: Royal Society of Chemistry
Tipo: Artigo de Revista Científica
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Nafion nanocomposite membranes were prepared from Nafion 117 and a systematic range of organically functionalized silicon alkoxide precursors using an in situ sol gel synthesis technique. The physical structure of the resulting nanocomposite membranes wer

Nanocomposite con actividad bactericida

Alonso González, Amanda; Muñoz Tapia, María
Fonte: Madrid : Oficina Española de Patentes y Marcas, Publicador: Madrid : Oficina Española de Patentes y Marcas,
Tipo: Patente Formato: application/pdf
Publicado em //2010 SPA
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Nanocomposite con actividad bactericida. La presente invención se refiere a la síntesis de un nuevo nanocomposite que contiene nanopartículas metálicas de tamaño y morfología controlada de tipo núcleo recubierto, insertadas y estabilizadas en una matriz de intercambio iónico formada por fibras poliméricas caracterizadas por presencia de grupos funcionales con un pKa<4, preferentemente grupos sulfónicos. El núcleo de la nanopartícula está formado por un metal con propiedades ferromagnéticas, preferentemente el cobalto, y el recubrimiento, por un metal con capacidad bactericida, preferentemente la plata. Las propiedades ferromagnéticas permiten recoger mediante trampas magnéticas las posibles nanopartículas que se puedan desprender del nanocomposite, evitando así la contaminación del medio tratado. Además gracias a su gran capacidad bactericida se pueden utilizar para la descontaminación y/o desinfección de diferentes medios, como puede ser el agua.

Nanocomposite con actividad bactericida

Alonso González, Amanda; Muñoz Tapia, María
Fonte: Madrid : Oficina Española de Patentes y Marcas, Publicador: Madrid : Oficina Española de Patentes y Marcas,
Tipo: Patente Formato: application/pdf
Publicado em //2009 SPA
Relevância na Pesquisa
37.206987%
Nanocomposite con actividad bactericida. La presente invención se refiere a la síntesis de un nuevo nanocomposite que contiene nanopartículas metálicas de tamaño y morfología controlada de tipo núcleo recubierto, insertadas y estabilizadas en una matriz de intercambio iónico formada por fibras poliméricas caracterizadas por la presencia de grupos funcionales con un pKa<4, preferentemente grupos sulfónicos. El núcleo de la nanopartícula está formado por un metal con propiedades ferromagnéticas, preferentemente el cobalto, y el recubrimiento, por un metal con capacidad bactericida, preferentemente la plata. Las propiedades ferromagnéticas permiten recoger mediante trampas magnéticas las posibles nanopartículas que se puedan desprender del nanocomposite, evitando así la contaminación del medio tratado. Además gracias a su gran capacidad bactericida se pueden utilizar para la descontaminación y/o desinfección de diferentes medios, como puede ser el agua.

Organic/Inorganic Hybrid Nanocomposite Infrared Photodetection by Intraband Absorption

Lantz, Kevin Richard
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2011
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The ability to detect infrared radiation is vital for a host of applications that include optical communication, medical diagnosis, thermal imaging, atmospheric monitoring, and space science. The need to actively cool infrared photon detectors increases their operation cost and weight, and the focus of much recent research has been to limit the dark current and create room-temperature infrared photodetectors appropriate for mid-to-long-wave infrared detection. Quantum dot infrared photodetectors (QDIPs) provide electron quantum confinement in three dimensions and have been shown to demonstrate high temperature operation (T>150 K) due to lower dark currents. However, these inorganic devices have not achieved sensitivity comparable to state-of-the-art photon detectors, due in large part to the inability to control the uniformity (size and shape) of QDs during strained-layer epitaxy.

The purpose of this dissertation research was to investigate the feasibility of room-temperature infrared photodetection that could overcome the shortfalls of QDIPs by using chemically synthesized inorganic colloidal quantum dots (CQDs). CQDs are coated with organic molecules known as surface ligands that prevent the agglomeration of dots while in solution. When CQDs are suspended in a semiconducting organic polymer...

Corrosion Behavior of Electroless Ni-P-TiO2 Nanocomposite Coatings and Optimization of Process Parameters Using Taguchi Method

Hosseini,J.; Bodaghi,A.
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
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This paper reports an experimental study of corrosion characteristics of electroless NiP- TiO2 nanocomposite coatings. Coating process parameters are optimized for maximum corrosion resistance based on L9 Taguchi orthogonal design with four process parameters, viz., concentration of nickel source solution, concentration of reducing agent, concentration of TiO2 powder and bath temperature. Corrosion behavior of the electroless Ni-P-TiO2 nanocomposite coatings was evaluated in 3.5 wt.% NaCl aqueous solution by using polarization technique. Scanning electron microscope (SEM) and Energy dispersive X-ray spectroscopy (EDS) analysis were used for studying the surface morphology and chemical composition of the electroless Ni-P-TiO2 nanocomposite coatings. The results showed that incorporation of TiO2 in coating causes increasing of corrosion resistance and improves surface morphology. Finally, optimum conditions were achieved as, concentration of nickel source solution: 50 g L-1 , concentration of reducing agent: 10 g L-1, concentration of TiO2 powder: 10 g L-1, and bath temperature of 85 °C.

SnO2/SiO2 nanocomposite catalyzed one-pot, four-component synthesis of 2-amino-3-cyanopyridines

Yelwande,Ajeet A.; Navgire,Madhukar E.; Tayde,Deepak T.; Arbad,Balasaheb R.; Lande,Machhindra K.
Fonte: South African Journal of Chemistry Publicador: South African Journal of Chemistry
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
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An efficient and rapid protocol for the synthesis of 2-amino-3-cyanopyridines by the cyclocondensation reaction of aromatic aldehydes, methyl ketones, malononitrile and ammonium acetate catalyzed by SnO2/SiO2 nanocomposite material at refluxed condition in ethanol was investigated. Nanocomposite (SnO2/SiO2) catalytic material has been synthesized by using the sol-gel method. The prepared catalytic materials were characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmer-Teller (BET) surface area, and temperature-programmed desorption of ammonia (NH3-TPD). Advantages of the present method include a simple work-up procedure, high yields of the products, low toxicity and easy recovery and reusability of the catalytic materials.