Search results for "Micro"

Nanoscale mechanical characterization of polymers by atomic force microscopy (AFM) nanoindentations: Viscoelastic characterization on a model material

2009

The Atomic Force Microscope (AFM), apart form its conventional use as a microscope, is also used for the characterization of the local mechanical properties of polymers. In fact, the elastic characterization of purely elastic materials using this instrument can be considered as a well assessed technique while the challenge remains the characterization of the viscoelastic mechanical properties. In particular, one finds the mechanical behavior changing when performing indentations at different loading rates, i.e., on different time scales. Moreover, this apparent viscoelastic behavior can also be due to complex contact mechanics phenomena, with the onset of plasticity and long-term viscoelast…

Nuove applicazioni dei polimeri mucoadesivi chitosano, glicole chitosano e loro derivati tiolati in campo biomedico-farmaceutico

2014

Microwave-assisted synthesis of semiconductor nanoparticles in water/oil microemulsion

2005

Stable CdS and ZnS nanoparticles with exalted luminescence properties have been obtained in water/sodium bis (2-ethylhexyl) sulfosuccinate (AOT)/n-heptane microemulsion using microwave in order to take away selectively water molecules from microemulsion system. The nanoparticles synthesis was performed using a microwave exposure set-up opportunely assembled that allows irradiating the reactor with microwave of 2.45 GHz maintaining constant the temperature. The nanoparticles growth kinetics, as a function of irradiation time, was performed by means of UV-Vis spectroscopy. Information about the structural changes that microemulsion undergoes when irradiated with microwave was obtained by mean…

Luminescence properties of neodymium-doped yttrium aluminium garnet obtained by the co-precipitation method combined with the mechanical process

2005

Nanopowders of yttrium aluminium garnet Y3Al5O12 (YAG) doped with neodymium ions were obtained by the co-precipitation method from the reaction of aluminium and yttrium nitrate and neodymium oxide with ammonia. After washing and drying the hydroxide precursors were calcined at 500, 700, 800 and 900 °C for 1 hour and at 1000 °C for 3 hours. This product was treated by ball milling in a zirconia vial for 0.5, 1.5 and 10 h in order to achieve smaller nanoparticles. The structure, microstructure, morphology and optical properties were investigated by means of diffractometric, microscopic and spectroscopic techniques. The course of the amorphous-to-crystalline transformation was complete after c…

Interaction en champ proche entre une sonde nanométrique et le champ de composants à cristal photonique:- interaction faible, microscopie spatialemen…

2008

With the improvement of fabrication techniques, the nanophotonics and more especially the photonics crystals which are periodic structure at the Wavelength scale have been recently developed. In this work, by using a scanning near-field optical microscope, we study such components. Firslty, we use the local probe to visualize the light distribution inside photonic crystal microcavities etched into semiconductor III/V. We focus us on the explanation of the near-field maps formation and on the probe influence on these maps. Thus, we have visualize degeneracy splitting of optical cavity modes and clearly observed in near-field cavity modes which were not visible in far-field. Moreover, in the …

Etude en champ proche et en champ lointain de composants périodiquement nanostructurés : cristaux photoniques et tamis à photons

2004

Recently, a new class of optical components is appeared. Its main characteristic is to be formed by a periodical sub-wavelength pattern, leading to the apparition of a spectral domain where propagation of light inside the structure is forbidden -- a photonic bandgap. This work is devoted to the study in the near- and far-field of two kinds of periodical optical components: photonic crystals (PCs) and nanostructured metallic films that exhibit the so-called enhanced transmission. First, we study two-dimensional PCs with a scanning near-field optical microscope (SNOM) in collection mode. With this SNOM, we directly map the intensity distribution inside PC-based microcavities. We also evidence…

Preparation of Nd:YAG Nanopowder in a Confined Environment

2007

Nanopowder of yttrium aluminum garnet (YAG, Y3Al5O12) doped with neodymium ions (Nd:YAG) was prepared in the water/cetyltrimethylammonium bromide/1-butanol/n-heptane system. Aluminum, yttrium, and neodymium nitrates were used as starting materials, and ammonia was used as a precipitating agent. Coprecipitate hydroxide precursors where thermally treated at 900 degrees C to achieve the garnet phase. The starting system with and without reactants was characterized by means of the small-angle neutron scattering technique. The system, without reactants, is constituted by a bicontinuous structure laying near the borderline with the lamellar phase region. The introduction of nitrates stabilizes th…

Three-Dimensional Superconducting Nanohelices Grown by He

2019

Novel schemes based on the design of complex three-dimensional (3D) nanoscale architectures are required for the development of the next generation of advanced electronic components. He+ focused-ion-beam (FIB) microscopy in combination with a precursor gas allows one to fabricate 3D nanostructures with an extreme resolution and a considerably higher aspect ratio than FIB-based methods, such as Ga+ FIB-induced deposition, or other additive manufacturing technologies. In this work, we report the fabrication of 3D tungsten carbide nanohelices with on-demand geometries via controlling key deposition parameters. Our results show the smallest and highest-densely packed nanohelix ever fabricated s…

Narratives of children with high-functioning autism spectrum disorder: A meta-analysis

2016

Abstract Background The aim of this meta-analysis was to analyze the narrative performance of children and adolescents with high-functioning Autism Spectrum Disorders (ASD) in terms of microstructure, macrostructure and internal state language. Method A systematic literature search yielded 24 studies that met the predetermined inclusion criteria. Effect sizes for each study were calculated for eight variables and analyzed using a random effects model. Intellectual ability, age and type of narrative were considered as potential moderators. Results Results revealed that the children with ASD performed significantly worse than their peers on all the variables considered. Conclusions Findings a…

Elemental and microbiota content in indoor and outdoor air using recuperation unit filters

2021

Detection and quantification of engineered nanomaterials in environmental systems require precise knowledge of the elemental composition, association, and ratios in homologous natural nanomaterials (NNMs). Here, we characterized soil NNMs at the single particle level using single particle-inductively coupled plasma-time of flight-mass spectrometer (SP-ICP-TOF-MS) in order to identify the elemental purity, composition, associations, and ratios within NNMs. Elements naturally present as a major constituent in NNMs such as Ti, and Fe occurred predominantly as pure/single metals, whereas elements naturally present at trace levels in NNMs occurred predominantly as impure/multi-metal NNMs such as…