Search results for "composites"

Ultralow-intensity near-infrared light induces drug delivery by upconverting nanoparticles

2014

Mesoporous silica coated upconverting nanoparticles are loaded with the anticancer drug doxorubicin and grafted with ruthenium complexes as photoactive molecular valves. Drug release was triggered by 974 nm light with 0.35 W cm(-2). Such low light intensity minimized overheating problems and prevented photodamage to biological samples.

Detection and characterisation of disbonds on Fibre Metal Laminate hybrid composites by flying laser spot thermography

2017

Abstract In this work a novel data collection and processing is proposed for the Infrared Non-Destructive Testing (IR-NDT) of interlaminar disbonds on Fibre Metal Laminate (FML) hybrid composites. The adopted active IR-NDT scheme uses a pointwise laser heat source that is moved along a raster scanning trajectory over the object surface. A Focal Plane Array IR camera is employed to acquire the thermal field generated by the moving heat source. Disbonds defect signatures are then searched by analysing the perturbations of the temperature distribution over a reference area following the heat source. The proposed methodology has been implemented on a GLARE sample, since this class of FMLs has g…

Corrigendum to “Far-infrared and THz spectroscopy of 0.4PMN–0.3PSN–0.3PZN relaxor ferroelectric ceramics” [J. Eur. Ceram. Soc. 27 (2007) 3713–3717]

2007

Influence of orientation errors on quasi-homogeneity of composite laminates

2003

This paper presents a study on the effects of layer orientation defects on the property of quasi-homogeneity for composite laminates: a measure of the deviation from quasi-homogeneity, introducing the concept of degree of quasi-homogeneity, is proposed. Complete theoretical developments which lead to exact formulae in the case of a single orientation error on a layer of the laminate are showed and the results of a wide numerical analysis in the case of orientation errors randomly distributed on the stacking sequence are also presented. All the theoretical and numerical calculations are developed thanks to the polar method of representation of fourth order tensors introduced by Verchery.

Continuous Broadband MWP True-Time Delay with PbS-PMMA and -SU8 waveguides

2016

[EN] A new microwave true-time delay (TTD) photonic unit based on the dispersion of PbS colloidal quantum dots (QDs) in a Polymethyl methacrylate (PMMA) and the SU8 photoresist is presented. With this aim, the PbS-PMMA and PbS-SU8 nanocomposites are integrated on a silicon platform in the form of a planar and ridge waveguides, respectively. When PbS QDs on those structures are pumped below their band-gap, a phase shift and a temporal delay in an optically conveyed (at 1550 nm) microwave signal is performed. The results of these devices show potential benefits over current TTD technologies, since the proposed photonic waveguide structures allows real-time adjustment of the temporal delay by …

FERROELECTRIC LIQUID CRYSTAL GLASSES FOR AMBLYOPIA RESEARCH

2008

ABSTRACT Ferroelectric Liquid Crystal (FLC) filters offer the speed of electronic light shutters and the vibration free operation. These characteristics make them ideal for applications requiring short exposure times and minimal blur, offering switching times of 0.0002 of a second. FLC filters can be used as the optical shutters for machine vision purposes, also in vision research. On the basis of FLC filters we have developed ferroelectric glasses, allowing temporal separation of optical information for both eyes. In the case of amblyopia (“lazy eye”) the only way to oblige the “lazy” eye to work is to close the other better-seeing eye. We advice an appliance for dynamic visual system trai…

Structure-property relationship of PLA-Opuntia Ficus Indica biocomposites

2019

Abstract In this work, a lignocellulosic flour was achieved by grinding the cladodes of Opuntia Ficus Indica and then added to a poly-lactic acid (PLA) in order to prepare biocomposites by melt processing. The influence of filler content and size on the morphological, rheological, and mechanical properties of the green composites was assessed. Moreover, solvent-aided filler extraction enabled to evaluate the homogeneity of filler dispersion, as well as the effect of processing on the geometrical features of the fillers. The experimental data obtained by tensile tests proved to be remarkably higher than those predicted by Halpin–Tsai model, presumably due to the capability of the polymer to …

Upconversion luminescence in erbium doped transparent oxyfluoride glass ceramics containing hexagonal NaYF4 nanocrystals

2015

Abstract In this work transparent erbium doped oxyfluoride glass ceramics containing hexagonal NaYF 4 nanocrystals has been prepared by melt-quenching and subsequent heat treatment of the precursor glass. The formation of β-NaYF 4 was confirmed by X-ray diffraction measurements. The overall intensity of the upconversion luminescence of the glass ceramics sample is 2 orders of magnitude higher than that of the precursor glass. The observed enhancement of the efficiency is explained by the incorporation of Er 3+ into low-phonon β-NaYF 4 crystalline phase.

X-ray micro-tomography based FEM modelling of hygroexpansion in PLA composites reinforced with birch pulp fibres

2017

This article presents a microscale modelling approach coupled with X-ray computed micro-tomography for the evaluation of material properties of polylactic acid (PLA) reinforced by birch pulp fibers under the effect of moisture. The results in terms of elastic moduli and hygroexpansion deformation were found in good agreement with the measurements taken at different levels of water uptake.

Effects of Nylon 6,6 Nanofibrous Mats on Thermal Properties and Delamination Behavior of High Performance CFRP Laminates

2014

none 8 no Nylon 6,6 electrospun nanofibrous membranes interleaved in Carbon Fibre Reinforced Plastic (CFRP) laminates have been proposed as a means to provide a higher threshold value to delamination on structural sites where composites are more prone to develop such failure. A model, highly crosslinked thus inherently brittle, epoxy matrix was selected for its high Young’s modulus and glass transition temperature exceeding 250 °C. The influence of the Nylon 6,6 nanofibres on the curing behaviour of the matrix and on the thermal and dynamic mechanical properties of the cured resin was investigated. These properties were related to the features of the epoxy resin and of the resin impregnated…