Search results for "CERAMICS"
showing 10 items of 1599 documents
Long-term results after operative treatment of femoral neck fractures with ceramic head prostheses.
2001
ABSTRACT From 1 985-1 990, a total of 277 elderly patients underwent hemiarthroplasty using a ceramic head prosthesis. Average patient age was 81.7 years. Of these, 77 patients were available for follow-up examination in 1993. A standardized score was calculated assessing activity, gait, and hip pain; the average score was 58 out of 78 possible points. Three patients had hip pain, and in 4 patients, radiographic examination revealed protrusio acetabuli. Two of 4 patients underwent revision surgery for replacement of the cup, leaving the stem in situ. Because of the small number of prosthetic-related complications, hemiarthroplasty using a ceramic head prosthesis is the recommended surgical …
Influence of some relevant process parameters on the dimensional accuracy in incremental forming: a numerical and experimental investigation
2004
Abstract As known, incremental forming is a flexible and innovative sheet metal forming process which allows complex shape shells forming without the need for any die. For these reasons, incremental forming is nowadays suggested for rapid prototyping and customised products. The present paper is focused on material formability in incremental forming and, in particular, on the evaluation and compensation of elastic springback. The latter significantly modifies the imposed shape. For this purpose, a deeper assessment of the process was developed following three different approaches. First of all, a wide experimental investigation on the influence of some relevant process parameters was develo…
X-ray powder diffraction study of monoclinic V4+-ZrO2 solid solutions obtained from gels
2003
Abstract Rietveld refinement of six monoclinic V x Zr 1− x O 2 solid solutions, with x =0, 0.01, 0.02, 0.05, 0.075 and 0.1, prepared by heating dried gel precursors at 1300°C in air atmosphere, has been characterized using X-ray powder diffractometer data. The present results confirm that crystal structure of these solid solutions contain V 4+ (Zr 4+ ) cations surrounded by seven oxygens, four at a distance between 2.13 and 2.28 A (referred as to O(2) in the tetrahedrally coordinated oxygens) and other three at a distance between 2.03 and 2.20 A (denoted as O(1) in the triangularly coordinated oxygens). The trends in the lattice parameter variation of V x Zr 1− x O 2 solid solutions specime…
Cerium effect on the phase structure, phase stability and redox properties of Ce-doped strontium ferrates
2006
Nanostructured perovskite-type Sr1−aCeaFeO3−x, (0⩽a<0.15) powders have been prepared by citrate–nitrate smoldering auto-combustion. Their phase structure and stability, surface and morphological properties, reduction behavior and interaction with oxygen have been investigated by X-ray Powder Diffraction combined with Rietveld Analysis, 57Fe Mossbauer and X-ray Photoelectron Spectroscopies, N2-adsorption method, Temperature Programmed Reduction and Oxidation experiments. Our results reveal that citrate–nitrate auto-combustion method is effective in obtaining single phase Sr1−aCeaFeO3−x. The Sr1−aCeaFeO3−x structure is cubic only for a⩾0.06, while for a<0.06 remains tetragonal. Moreover, for …
Structural and morphological properties of Co-La catalysts supported on alumina/lanthana for hydrocarbons oxidation
2004
Abstract Two Al 2 O 3 (24 wt%)–La 2 O 3 (76 wt%) supported Co–La oxides with Co loading 4 wt% and different La content (1 and 9 wt%) were prepared by co-impregnation of the support, the aluminum–lanthanum oxide, with cobalt and lanthanum nitrates in aqueous solution and successive calcination at 800 °C for 4 h. The alumina–lanthana was synthesized by the sol–gel method. The samples were characterized by X-ray diffraction (XRD) and Rietveld refinement in order to identify the crystalline phases and their relative weight. H 2 -TPR (Temperature Programmed Reduction) experiments were recorded with the aim to identify the different Co phases present. Co 3 O 4 and LaCoO 3 were formed for La loadi…
Formation of an interlocked double-chain from an organic-inorganic [2]rotaxane.
2019
Here we show that a structure containing a polymeric interlocking daisy chain is obtained from the reaction of an inorganic–organic [2]rotaxane [HB{CrIII7NiII(μ-F)8(O2CtBu)16}], where B is an organic thread terminated with a bi-pyridyl unit, with an oxo-centered metal carboxylate triangle [FeIII2CoII(μ3-O)(O2CtBu)6(HO2CtBu)3].
Bending effect on the risk for delamination at the reinforcement/matrix interface of 3D woven fabric composite using a shell-like RVE
2012
This paper presents a computational homogenisation-based technique for flexural effects in textile reinforced composite planar shells. An homogenisation procedure is used for the in-plane and the out-of-plane behaviour of three-dimensional woven composite shells, taking the in-plane periodicity of the material into account while relaxing any periodicity tying in the thickness direction. Several types of damage (matrix or reinforcement cracking, delamination, …) can appear in a composite material. In this paper, material non-linear computations are used to assess the importance of bending on the risk for delamination at the reinforcement/matrix interface. The normal and tangential stresses a…
Radioluminescence, thermoluminescence and dosimetric properties of ZnO ceramics
2017
The authors gratefully acknowledge the financial support for this work from research grant ERA.NET RUS Plus Nr.609556 and from the SFERA II project Transnational Access activities (EU 7th Framework Programme Grant Agreement no 312643) for supporting ZnO nanopowders preparation.
Layer thickness optimisation in a laminated composite
1997
Abstract The paper describes a method to optimise the thickness balance within a composite laminate with layers oriented according to a limited set of angles. The laminate must be symmetric, balanced and loaded in-plane. The optimisation process is particularly suited to be used in conjunction with a finite element program. It provides the designer with the optimal overall engineering characteristics anda list of all the possible orientation combinations ranked with respect to their safety factor. The optimisation method is based on the first order gradient optimum search method and operates iteratively in the engineering elastic characteristics field. The cost function implemented up to no…
Channeled scaffolds implanted in adult rat brain.
2012
Scaffolds with aligned channels based on acrylate copolymers, which had previously demonstrated good com- patibility with neural progenitor cells were studied as coloniz- able structures both in vitro with neural progenitor cells and in vivo, implanted without cells in two different locations, in the cortical plate of adult rat brains and close to the subven- tricular zone. In vitro, neuroprogenitors colonize the scaffold and differentiate into neurons and glia within its channels. When implanted in vivo immunohistochemical analysis by confocal microscopy for neural and endothelial cells markers demonstrated that the scaffolds maintained continuity with the surrounding neural tissue and wer…