63 research outputs found
One step growth of GaN/SiO2 core/shell nanowire in vapor-liquid-solid route by chemical vapor deposition technique
GaN/SiO2 core/shell nanowires are grown by cobalt phthalocyanine catalyst
assisted vapor-liquid-solid route, in which Si wafer coated with a mixture of
gallium and indium is used as the source for Ga and Si and ammonia is used as
the precursor for nitrogen and hydrogen. Gallium in the presence of indium and
hydrogen, which results from the dissociation of ammonia, forms Si-Ga-In alloy
at the growth temperature around 910 degree Celsius. This alloy acts as the
source of Si, Ga and In. A detailed study using a variety of characterization
tools reveals that these wires, which are several tens of micron long, has a
diameter distribution of the core ranging from 20 to 50 nm, while the thickness
of the amorphous SiO2 shell layer is about 10 nm. These wires grow along
direction. It has also been observed that the average width of these wires
decreases, while their density increases as the gallium proportion in the Ga-In
mixture is increased.Comment: 14 pages, 4 figure
Selective detection of fluoride and hydrogen sulfate anions by pyrimidine-based fluorescence chemosensor
1809-1813The binding and sensing abilities of pyrimidine based fluorescence chemosensor L towards different anions such as F-, Cl-, Br-, I-, NO3-, ClO4-, H2PO4- and HSO4- have been examined by fluorescence spectroscopy in DMSO-H2O (7: 3, v/v). Upon successive addition of various anions to DMSO-H2O solutions of L; quenching in emission fluorescence is observed at 480 nm. Analysis of fluorescence emission changes suggested the formation of 1:1 complex of L with the anions. From the fluorescence binding constant data, it is found that L form strong complexes with F- and HSO4- ions through H-bonding interactions. The selective response of F- over other halides and HSO4- amongst other oxo-anions towards L may be explained on the basis of photo-induced electron transfer process
Caracterização térmica e dinâmico-mecânica de compósitos TPU/mica preparados em reômetro de torque
Biocomposite films based on κ-carrageenan/locust bean gum blends and clays : physical and antimicrobial properties
The aims of this work were to evaluate the physical and antimicrobial properties of biodegradable films composed of mixtures of κ-carrageenan (κ-car) and locust bean gum (LBG) when organically modified clay Cloisite 30B (C30B) was dispersed in the biopolymer matrix. Film-forming solutions were prepared by adding C30B (ranging from 0 to 16 wt.%) into the κ-car/LBG solution (40/60 wt.%) with 0.3 % (w/v) of glycerol. Barrier properties (water vapour permeability, P vapour; CO2 and O2 permeabilities), mechanical properties (tensile strength, TS, and elongation-at-break, EB) and thermal stability of the resulting films were determined and related with the incorporation of C30B. Also, X-ray diffraction (XRD) was done in order to investigate the effect of C30B in film structure. Antimicrobial effects of these films against Listeria monocytogenes, Escherichia coli and Salmonella enterica were also evaluated. The increase of clay concentration causes a decrease of P vapour (from 5.34 × 10−11 to 3.19 × 10−11 g (m s Pa)−1) and an increase of the CO2 permeability (from 2.26 × 10−14 to 2.91 × 10−14 g (m s Pa)−1) and did not changed significantly the O2 permeability for films with 0 and 16 wt.% C30B, respectively. Films with 16 wt.% clay exhibited the highest values of TS (33.82 MPa) and EB (29.82 %). XRD patterns of the films indicated that a degree of exfoliation is attained depending on clay concentration. κ-car/LBG–C30B films exhibited an inhibitory effect only against L. monocytogenes. κ-car/LBG–C30B composite films are a promising alternative to synthetic films in order to improve the shelf life and safety of food products.J. T. Martins, A. I. Bourbon, A. C. Pinheiro and M. A. Cerqueira gratefully acknowledge the Fundacao para a Ciencia e Tecnologia (FCT, Portugal) for their fellowships (SFRH/BD/32566/2006, SFRH/BD/73178/2010, SFRH/BD/48120/2008 and SFRH/BPD/72753/2010, respectively), and B. W. S. Souza acknowledges the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, Brazil)
Investigation of structural, electrical and magnetic characterization of erbium substituted lead free electronic materials
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