Search results for "CERAMICS"
showing 10 items of 1599 documents
La nécropole Néolithique moyen d’Obernai ‘Neuen Brunnen’ (Bas-Rhin) : rites funéraires de la première moitié du 5e millénaire dans le sud de la plain…
2020
The Obernai ’Neuen Brunnen’ necropolis in Lower Alsace yielded 29 tombs attributed to the Middle Neolithic. It was probably founded during the Early Grossgartach, at the end of the 48th century BC, and abandoned during the Roessen, perhaps during the Early Roessen, and in any case before the middle of the 46th century BC. The most original feature of this mortuary assemblage is that most of the tombs belong to the Planig-Friedberg period (the last stylistic phase of the Grossgartach) and the Roessen. The mortuary practices of these periods are still poorly known in the region. The necropolis is composed of three spatial groups, the most ancient of which contains all the Grossgartach tombs a…
Effect of bioglass on growth and biomineralization of SaOS-2 cells in hydrogel after 3D cell bioprinting.
2014
We investigated the effect of bioglass (bioactive glass) on growth and mineralization of bone-related SaOS-2 cells, encapsulated into a printable and biodegradable alginate/gelatine hydrogel. The hydrogel was supplemented either with polyphosphate (polyP), administered as polyP • Ca2+-complex, or silica, or as biosilica that had been enzymatically prepared from ortho-silicate by silicatein. These hydrogels, together with SaOS-2 cells, were bioprinted to computer-designed scaffolds. The results revealed that bioglass (nano)particles, with a size of 55 nm and a molar ratio of SiO2 : CaO : P2O5 of 55 : 40 : 5, did not affect the growth of the encapsulated cells. If silica, biosilica, or polyP …
Implant-supported metal-ceramic and resin-modified ceramic crowns: A 5-year prospective clinical study.
2018
Abstract Statement of problem Because of market demand for innovation, new restoration materials have been introduced without adequate testing; clinical failure may be the consequence, and clinical studies are needed. Purpose The purpose of this clinical study was to evaluate the biological and mechanical clinical behavior of implant-supported resin-modified ceramic crowns compared with that of metal-ceramic crowns. Material and methods Forty-two participants aged between 35 and 65 years received single implants in posterior edentulous sites. After the osseointegration period, half of the implants (selected randomly) (n=25) were restored with metal-ceramic crowns (MC group) and the other ha…
Tissue reactions to glass ceramics in the middle ear
1981
The bioactive glass ceramic "Ceravital" was used to fashion prostheses for the replacement of various ossicles in the middle ear. They were tested in 70 rabbit ears, where they were accepted in osseous areas without formation of surrounding fibrous tissue. Histological examinations regularly showed an osseous bond with the surrounding bony tissue. Mucous membrane covered these ossicular chain prostheses and showed no evidence of inflammatory reactions. Glass ceramic implants were also used to reconstruct the ossicular chain and the posterior wall of the outer ear canal in 100 patients. The functional results were satisfactory in all cases.
EXAFS study of ceria–lanthana-based TWC promoters prepared by sol–gel routes
2003
Extended X-ray absorption fine structure (EXAFS) experiments at the Ce K- and La K-edges were performed on ceria–lanthana–alumina three-way catalysts promoters prepared by sol–gel routes, in order to investigate the effect of lanthanum doping on the ceria structure. The formation of Ce1−xLaxO2−x/2 solid solution, already observed by X-ray diffraction, was confirmed by EXAFS analysis, while no experimental evidence of a Ce–Al interaction was found. In presence of cerium and aluminum, lanthanum is involved in the formation of solid solution with CeO2 and of La–Al compounds. When the La:Al molar ratio is sufficiently high, the growth of a tridimensionally ordered LaAlO3 perovskite compound is …
Growth of nano-porous Pt-doped cerium oxide thin films on glassy carbon substrate
2013
Abstract Glassy carbon (GC) substrates were treated by the oxygen plasma over several periods of time. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) study showed the dramatic influence of oxygen plasma on the morphology of glassy carbon. The treatment leads to the formation of nanostructured surface, which consists of well separated rod-like nanostructures oriented perpendicularly to the substrate surface. The surface roughness was found to increase with increasing treatment time. By using magnetron co-sputtering of platinum and cerium oxide we can prepare oxide layers continuously doped with Pt atoms during the growth. This tec…
Enhanced quantum sieving of hydrogen isotopes via molecular rearrangement of the adsorbed phase in chabazite
2020
Coadsorption experiments reveal an unexpected increase of the D2/H2 selectivity with loading in pure silica chabazite at 47 K. This effect is correlated with the appearance of a step in the adsorption isotherms of H2 and D2. Grand canonical Monte Carlo simulations show that this phenomenon is related to a molecular rearrangement of the adsorbed phase induced by its strong confinement. In the case of a H2 and D2 mixture, this rearrangement favors the adsorption of D2 having a smaller size due to quantum effects.
Chromogenic and fluorogenic reagents for chemical warfare nerve agents' detection
2008
The ease of production, the extreme toxicity of organophosphorus-containing nerve agents, and their facile use in terrorism attacks underscores the need to develop accurate systems to detect these chemicals. Among different technologies we review here recent advances in the design of chromo-fluorogenic methods for the specific detection of nerve agents. Optical sensing (especially colorimetric detection) requires usually low-cost and widely used instrumentation and offers the possibility of so-called “naked eye detection”. Recent reported examples suggest that the application of chromo-fluorogenic supramolecular concepts for the chromogenic or fluorogenic sensing of nerve agents might be an…
Creep and recovery of epoxy/MWCNT nanocomposites
2012
Abstract Creep and creep–recovery of epoxy/multi-wall carbon nanotube (MWCNT) composites was studied in a wide range of applied loads in order to evaluate the contribution of nanotubes on the time-dependent behaviour of the epoxy matrix. Incorporation of up to 1 wt.% of C150P MWCNTs has negligible influence on the elastic, viscoelastic and viscoplastic response of the epoxy system. No systematic changes of the creep characteristics depending on the content of nanotubes are noticed in the range of stresses from 0.3 up to 0.75 from the ultimate strength. Creep resistance and recovery performance of the epoxy matrix is not negatively affected by the addition of MWCNTs and the same analytical m…
Discrimination of nerve gases mimics and other organophosphorous derivatives in gas phase using a colorimetric probe array.
2012
A colorimetric array for the chromogenic discrimination of organophosphorous derivatives in gas phase has been developed. The array allows us to classify the nerve agent simulants DFP, DCP and DCNP.