Current Issue : April - June Volume : 2014 Issue Number : 2 Articles : 5 Articles
Efficient silicon-based light emitters continue to be a challenge. A great effort has been made in photonics to modify silicon in order\r\nto enhance its light emission properties. In this aspect silicon nanocrystals (Si-NCs) have become themain building block of silicon\r\nphotonic (modulators, waveguide, source, and detectors). In this work, we present an approach based on implantation of Ag (or Au)\r\nions and a proper thermal annealing in order to improve the photoluminescence (PL) emission of Si-NCs embedded in SiO2. The\r\nSi-NCs are obtained by ion implantation at MeV energy and nucleated at high depth into the silica matrix (1-2 ??m under surface).\r\nOnce Si-NCs are formed inside the SiO2 we implant metal ions at energies that do not damage the Si-NCs. We have observed by,\r\nPL and time-resolved PL, that ion metal implantation and a subsequent thermal annealing in a hydrogen-containing atmosphere\r\ncould significantly increase the emission properties of Si-NCs. Elastic Recoil Detection measurements show that the samples with\r\nan enhanced luminescence emission present a higher hydrogen concentration. This suggests that ion metal implantation enhances\r\nthe hydrogen diffusion into silica matrix allowing a better passivation of surface defects on Si NCs....
Dental implant fracture is a rare biomechanical complication, however, one of the most serious and frustating ones as it is generally\r\nassociated with implant and prosthesis failure as well as the surgical hazards of explantation and reimplantation. To gain insights\r\ninto implant fracture rates and the impact of patient-, surgery-, and prosthetic-related factors, systematic review and meta-analysis\r\nof the English literature were performed. Electronic and hand searches yielded 69 relevant publications reporting on 827 fractures\r\nout of 44521 implants investigated. The overall incidence of implant fractures was 1.6%. Mean patient age at the time of implant\r\nfracture was 54 �± 11 years, and 70% occurred in males.Thevast majority (85%) occurred in posterior regions of themouth (premolar\r\nor molar positions). No tendency of increased fracture rates could be noted for short implant lengths or narrow implant diameters.\r\nImplant fractures occurred after 4.1 �± 3.5 years of loading, on average, in most cases (88%) supporting fixed restorations; however,\r\nonly 56% were preceded by screw loosening. Although further investigations are needed to fully explore the characteristics and\r\ncauses of this rare complication, it can be concluded that no more than 2.8% of implants fracture is within a mean loading period\r\nof 8.3 years....
Poly(3-hydroxybutyrate) (PHB) is a polyester which shows excellent biocompatibility and a PHB material is therefore considered\r\nsuitable for many biomedical applications. A highly porous PHB material may be designed to facilitate the transport of small\r\nmolecules and body fluids or serve as a biocompatible temporary barrier. In this study,PHBfilms with varying degree of porosity and\r\npore interconnectivitywere made by solvent casting usingwater-in-oil emulsion templates of varying composition.Themorphology\r\nwas characterized by SEMand the water permeability of the films was determined.The results show that an increased water content\r\nof the template emulsion resulted in a film with increased porosity. A fine tuning of the film morphology of the casted films was\r\nachieved by varying the salt content of the water phase of the template emulsion. The porosity of these films was roughly the same\r\nbut the water permeability varied between 23�·10-13 and 1486�·10-13 m2/s. It was concluded that themajor determinant of the water\r\npermeability through these films is the pore interconnectivity. Furthermore, we report on the formation and water permeability of\r\nbilayer PHB films consisting of a porous layer combined with a dense backing layer....
The role of Propionibacterium acnes in acne and in a wide range of inflammatory diseases is well established. However, P. acnes is\r\nalso responsible for infections involving implants. Prolonged aerobic and anaerobic agar cultures for 14 days and broth cultures\r\nincrease the detection rate. In this paper, we review the pathogenic role of P. acnes in implant-associated infections such as\r\nprosthetic joints, cardiac devices, breast implants, intraocular lenses, neurosurgical devices, and spine implants. The management\r\nof severe infections caused by P. acnes involves a combination of antimicrobial and surgical treatment (often removal of the device).\r\nIntravenous penicillin G and ceftriaxone are the first choice for serious infections, with vancomycin and daptomycin as alternatives,\r\nand amoxicillin, rifampicin, clindamycin, tetracycline, and levofloxacin for oral treatment. Sonication of explanted prosthetic\r\nmaterial improves the diagnosis of implant-associated infections. Molecular methods may further increase the sensitivity of P.\r\nacnes detection. Coating of implants with antimicrobial substances could avoid or limit colonization of the surface and thereby\r\nreduce the risk of biofilm formation during severe infections. Our understanding of the role of P. acnes in human diseases will\r\nlikely continue to increase as new associations and pathogenic mechanisms are discovered....
Osseointegration is dependent on implant surface characteristics, including surface chemistry and topography. The presence of\r\nnanosized calcium phosphates on the implant surface is interesting to investigate since they affect both the nanotopography and\r\nsurface chemistry, forming a bone mineral resembling surface. In this work, the osseointegration of titanium implants with and\r\nwithout the presence of hydroxyapatite (HA) nanocrystals has been evaluated in vivo.The integration was examined using removal\r\ntorque measurements and real-time polymerase chain reaction (RT-PCR) analysis. The study was performed using two healing\r\ntime points, 3 and 12 weeks. The results showed that the torque needed to remove the implants was insignificant between the nonand\r\nHA-coated implants, both at weeks 3 and 12. The RT-PCR, however, showed significant differences for osteoblast, osteoclast,\r\nand proinflammation markers when HA nanocrystals were present....
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