Search results for "Matrix"
showing 10 items of 3205 documents
Fibrin-chitosan composite substrate for in vitro culture of chondrocytes
2013
The aim of this study was to develop a biocompatible monolayer substrate based on fibrin and chitosan for in vitro culture of chondrocytes. Fibrin-chitosan composite substrates combined the proved cell adhesion properties of fibrin with the hydrophilicity and poor adhesion capacity of chitosan. Chitosan microspheres were produced by coacervation method, agglomerated within a fibrin network and subsequently crosslinked with genipin. The composite substrate was stable for 28 days of culture due to the high crosslinking density. Human chondrocytes cultured on the composite substrate were viable during the culture period. At the end of culture time (28 days) the composite substrate showed low c…
Microstructural, mechanical and tribological properties of suspension plasma sprayed YSZ/h-BN composite coating
2018
Abstract Brittleness, relative high friction coefficient and wear rate limit the applications of ceramic coatings as wear-resistant layers. However, because embedding additives with ceramic matrix has demonstrated to be an effective way to improve coating performances, different contents and size of h-BN were added into an YSZ suspension. Afterwards, the YSZ/h-BN composite coatings were manufactured by suspension plasma spray and their tribological analysis indicated that: i) the reduction of the friction coefficient and wear rate can be achieved by incorporating h-BN into YSZ coating. ii) finer h-BN particle is more helpful to enhance the tribological properties of the coating. iii) the op…
Numerical simulations of the mechanical characteristics of glass fibre reinforced C-profiles
2006
A mechanical characterisation analysis on pultruded glass fibre reinforced C-shaped profiles, developed as modular construction elements to assemble fastening systems, such as doors, window frames and shutters is presented. The key idea is to perform the analysis, and all the related identification procedures of the material parameters, via a coupled approach, based on a limited number of standard laboratory tests and on the numerical finite element simulations of the same tests. The proposed approach allows one to identify all those material parameters which are difficult to detect, by means of simple laboratory experiments on specimens that are extracted from commercial products. It also …
Photonic band gaps in highly ionic medium: CuCl, CuBr, CuI
2003
Abstract Using the transfer-matrix-method, we have studied the propagation of electromagnetic waves through two-dimensional (2D) and three-dimensional (3D) dispersive photonic band gap (PBG) structures constructed from copper halides materials, especially from CuCl compounds. A special attention has been paid to the effect of the polariton gap on the PBG properties. This study reveals that “Twin gaps” and “Twin brothers” concepts and the flattened bands phenomena in both polarizations and for both structures (i.e. 2D and 3D) are all consequences of the strong photon–phonon coupling, particularly near the long wave length transverse optical phonon frequency. Furthermore, results for comparis…
TEXTURE PROBLEMS AND THE GOLDANSKII-KARAGIN EFFECT TREATED BY THE INTENSITY MATRIX METHOD
1979
The texture problem and the Goldanskii-Karyagin effect are easy to survey if the intensities of the transitions are written in terms of the intensity matrix. For pure magnetic and quadrupole interaction the equations are explicitly given.
CO2 to Liquid Fuels: Photocatalytic Conversion in a Continuous Membrane Reactor
2018
The photocatalytic reduction of CO, into value-added chemicals using sunlight is a promising approach to promote energy-bearing products, mitigating the adverse effects of anthropogenic CO2 emissions. In this work, exfoliated C3N4 was incorporated into Nafion matrix and used in a continuous photocatalytic reactor for converting CO2 into liquid fuels. Comprehensive structural and morphological diffuse reflectance spectroscopy (DRS), FT-IR, ATR-IR, and SEM measurements were performed for C3N4-loaded Nafion membrane and then compared with those of a Nafion membrane without any catalyst. The synergic effect of C3N4 organic catalyst embedded in a Nafion dense matrix and a continuous operating mo…
Micromechanisms of load transfer in a unidirectional carbon fibre–reinforced epoxy composite due to fibre failures. Part 2: Influence of viscoelastic…
2006
A local three-dimensional (3D) finite element analysis (FEA), of the mechanisms governing composite damage (in the region around a fibre break), has been carried out. The model considers viscoelastic and plastic matrix behaviours with and without debonding at the broken fibre/matrix interface. The finite element analysis has shown that even a simple viscoelastic law describing the behaviour of the epoxy resin leads to an increasing load on the neighbouring intact fibres, as a function of time. The plastic behaviour of the matrix has been shown to have consequences on reloading after unloading. In contrast to other studies reported in the literature, the calculations were carried out on diff…
Bioinspired Fabrication of Bio-Silica-Based Bone-Substitution Materials
2010
The gold standard for bone reconstruction is the use of autogeneic grafts from various donor regions, since they possess osteoinductive as well as osteoconductive potential. Only a few synthetic materials possess/display properties that allow optimal bone reconstitution. Previously, we showed that the natural product, bio-silica, comprises osteoinductive, and probably also osteoconductive activity. Bio-silica is formed enzymatically via silicatein; this enzyme has been isolated from siliceous sponges and has also been cloned and prepared recombinantly. In the present study, silicatein was encapsulated together with its substrate, sodium metasilicate, in poly(D,L-lactide)/poly(vinyl pyrrolid…
Determination of lifetime probabilities of carbon fibre composite plates and pressure vessels for hydrogen storage
2011
International audience; It is shown that an analogy can be made between the failure of unidirectional carbon fibre reinforced epoxy plates and filament wound carbon fibre composite pressure vessels and that their strengths and failure probabilities can be determined. Fibres in filament wound composite structures are placed on geodesic paths around the mandrel, which becomes the liner; so that when the structure is pressurised the fibres are only subjected to tensile forces, as in a unidirectional composite. Multiscale modelling reveals that composite failure is controlled by fibre breakage and that clustering of fibre breaks determines ultimate reliability of the structure. Time dependent r…
PBI mixed matrix hollow fiber membrane: Influence of ZIF-8 filler over H2/CO2 separation performance at high temperature and pressure
2020
High performance and commercially attractive mixed-matrix membranes were developed for H2/CO2 separation via a scalable hollow fiber spinning process. Thin (~300 nm) and defect-free selective layers were successfully created with a uniform distribution of the nanosized (~60 nm) zeolitic-imidazole framework (ZIF-8) filler within the polymer (polybenzimidazole, PBI) matrix. These membranes were able to operate at high temperature (150 °C) and pressure (up to 30 bar) process conditions required in treatment of pre-combustion and syngas process gas streams. Compared with neat PBI hollow fibers, filler incorporation into the polymer matrix leads to a strong increase in H2 permeance from 65 GPU t…