Search results for " composites"
showing 10 items of 1620 documents
Physical properties of (1−x)Ba0.95Pb0.05TiO3+xCo2O3 (x=0, 0.1, 0.3, 0.5, 1.0, 2.0wt%) ceramics
2015
The paper reports studies of the (1−x)Ba0.95Pb0.05TiO3 – xCo2O3 (x≤0.02) ceramics. Results of X-ray powder diffraction, dielectric, magnetic and IR measurements, as well as ab initio simulations are presented. The Co-doping induces small decrease of the (c/a) tetragonality of the perovskite lattice and leads to the gradual shift of the ferroelectric transition temperature from 398 K for x=0 down to 357 K for x=0.02. The conductivity activation energies are in the range 0.8–0.9 eV in agreement with the calculations. The high-temperature conductivity can be ascribed by the migration of oxygen vacancies introduced to compensate the charge deficiency due to Co3+ valence at the B-site of the per…
Modelling electric field control of the spin state in the mixed-valence polyoxometalate [GeV14O40]8−
2013
International audience; : The two-electron reduced mixed-valence polyoxometalate [GeV14O40](8-) presents an unusual paramagnetic behaviour as a consequence of the partial trapping of these electrons. The effect of applying an electric field is that of inducing antiferromagnetic coupling between the two delocalized electronic spins.
A discontinuous Galerkin formulation for variable angle tow composite plates higher-order theories
2020
A discontinuous Galerkin formulation for the mechanical behaviour of Variable Angle Tow multi-layered composite plates is presented. The starting point of the formulation is the strong form of the governing equations, which are obtained by means of the Principle of Virtual Displacement, the Generalized Unified Formulation and the Equivalent Single Layer assumption for the mechanical behaviour of the whole assembly. To obtain the corresponding discontinuous Galerkin formulation, an auxiliary flux variable is introduced and the governing equations are rewritten as a first-order system of partial differential equations. To link neighbouring mesh elements, suitably defined numerical fluxes are …
The impact of intercellular communication for the generation of complex multicellular prevascularized tissue equivalents
2019
In reconstructive surgery the use of prevascularized soft tissue equivalents is a promising approach for wound coverage of defects after tumor resection or trauma. However, in previous studies to generate soft tissue equivalents on collagen membranes, microcapillaries were restricted to superficial areas. In this study, to understand which factors were involved in the formation of these microcapillaries, the levels of the angiogenic factors vascular endothelial growth factor (VEGF), Interleukin-8 (IL-8), and basic fibroblast growth factor (bFGF) in the supernatants of the tissue equivalents were examined at various time points and conditions. Additionally, the influence of these factors on …
Scaffold vascularization in vivo driven by primary human osteoblasts in concert with host inflammatory cells.
2011
Successful cell-based tissue engineering requires a rapid and thorough vascularization in order to ensure long-term implant survival and tissue integration. The vascularization of a scaffold is a complex process, and is modulated by the presence of transplanted cells, exogenous and endogenous signaling proteins, and the host tissue reaction, among other influencing factors. This paper presents evidence for the significance of pre-seeded osteoblasts for the in vivo vascularization of a biodegradable scaffold. Human osteoblasts, cultured on silk fibroin micronets in vitro, migrated throughout the interconnected pores of the scaffold and produced extensive bone matrix. When these constructs we…
An equivalent single-layer model for magnetoelectroelastic multilayered plate dynamics
2012
Abstract An equivalent single-layer model for the dynamic analysis of magnetoelectroelastic laminated plates is presented. The electric and magnetic fields are assumed to be quasi-static and the first-order shear deformation theory is used. The formulation of the model provides for a preliminary fulfillment of the electro-magnetic governing equations, which allows to determine the electric and magnetic potential as functions of the mechanical variables. Then, by using this result, the equations of motion are written leading to the problem governing equations. They involve the same terms of the elastic dynamic problem weighted by effective stiffness coefficients, which take the magneto-elect…
Mechanical reinforcement of electrospun poly(vinyl alcohol) by α-FeOOH nanowires
2016
The authors kindly acknowledge the financial support of the Estonian Research Council for the post-doctoral research grants of personal research funding in projects PUT1096 and PUTJD578 as well as Institutional Research Funding Projects, IUT20-17, and IUT23-7.
Functionalised poly (vinyl alcohol)/graphene oxide as polymer composite electrolyte membranes
2019
[EN] Crosslinked poly(vinyl alcohol) (PVA) based composite films were prepared as polyelectrolyte membranes for low temperature direct ethanol fuel cells (DEFC). The membranes were functionalised by means of the addition of graphene oxide (GO) and sulfonated graphene oxide (SGO) and crosslinked with sulfosuccinic acid (SSA). The chemical structure was corroborated and suitable thermal properties were found. Although the addition of GO and SGO slightly decreased the proton conductivity of the membranes, a significant reduction of the ethanol solution swelling and crossover was encountered, more relevant for those functionalised with SGO. In general, the composite membranes were stable under …
Effect of TiO2 on the mullite formation and mechanical properties of alumina porcelain
2010
Abstract The effect of adding TiO 2 to standard alumina porcelain on its microstructure and flexural strength was investigated. A series of alumina porcelain bodies containing increasing amounts of TiO 2 were prepared by extruding mixtures of raw materials and TiO 2 . Porcelain rods were fired under industrial scheduling in a manufacturing kiln. The overall degree of crystalline and amorphous phase content within the porcelain bodies was quantitatively determined using a Rietveld analysis. Results indicated a higher amount of mullite formation in porcelain bodies containing TiO 2 . Examination of the product materials using field emission scanning electron microscopy showed a high density o…
Photocatalysis: a promising route for 21st century organic chemistry
2007
One of the main goals of 21st century chemistry is to replace environmentally hazardous processes with energy efficient routes allowing to totally avoid the use and production of harmful chemicals and to maximise the quantity of raw material that ends up in the final product. Selective photocatalytic conversions will play a major role in this evolution and this account shows how photocatalysis is offering an alternative green route for the production of organics.