167,920 research outputs found
Carbon incorporation in silicon-carbon films grown at different substrate temperatures
No full textHydrogenated microcrystalline silicon-carbon thin films have been deposited by plasma enhanced chemical vapour deposition technique at the substrate temperatures of 250 degrees C and 400 degrees C varying the radio frequency (RF) power in the 10- 100 W range. The effects of substrate temperature and RF power on the structural, compositional, optical, and electrical properties have been investigated. The increase of substrate temperature or RF power leads to a decrease of crystallinity degree and an enhancement of carbon content. Optical absorption in the UV-visible region and electrical conductivity are affected in a different way by the RF power and substrate temperature variations. Silicon grain nucleation of films deposited at the temperature of 250 degrees C on commercial doped tin oxide substrate has been explored, for different RF power, by means of X-ray diffraction measurements. (c) 2006 Elsevier B.V All rights reserved. RI Setaro, Antonio/D-1413-2010; Maddalena, Pasqualino/G-7114-201
Conservative treatment of hip osteoarthritis; comparison between three medium/high molecular weight hyaluronic acid injections and two injections of hyadd®4: A randomized controlled double-blind study
No full textTowards selective optochemical gas sensing by luminescent marine diatoms
No full textDiatom frustules are nanostructured silica shells that spontaneously arise in every aquatic environment. They strongly emit in the visible range when pumped up by UV radiation and their photoluminescence, in virtue of their high surface-to-volume ratio, is strongly affected by changes of the surrounding atmosphere. Frustules belonging to different families were exposed to various chemical species in order to test their reactivity to different polluting gases. Different species of diatoms were found to exhibit different relative responses and different gas concentration ranges of sensitivity, depending on the morphology and porosity of their frustules. Due to the large variety of dimensions, porosities and surface morphologies available in nature, these materials appear to be promising to improve the selectivity of gas sensing based on photoluminescence optochemical transduction, opening the way to the implementation of an all-optical analogous of the electronic nose
Marine diatoms as optical chemical sensors: A time-resolved study
No full textMarine diatoms are microscopic algae living in aquatic environment; their skeleton, made of amorphous silica, possesses a complex geometrical structure that presents holes on different length scales in a fractal-like fashion, achieving a high surface-to-volume ratio and making them good candidates for gas detecting purposes. Indeed, different gas species can influence diatoms' photoluminescence emission according to their different polarizing abilities. In particular, to exploit marine diatoms as optical nitrogen dioxide sensors and in order to get a better insight on the nature of the photoluminescence quenching process induced by the gas molecules, continuous-wave and time-resolved photoluminescence studies have been carried out, showing that nitrogen dioxide affects only the photoluminescence yield without altering the dynamics of the recombination process. © 2007 Elsevier B.V. All rights reserved
Synthesis of cobalt doped silica thin film for low temperature optical gas sensor
No full textA modified sol–gel method was used to prepare
cobalt doped silica thin film with a cobalt content of 10, 20
and 30 mol% (10Co, 20Co and 30Co). The prepared films
were annealed at different temperatures in the range
400–1,000 °C, and their structural evolution examined.
The mixed valence cobalt oxide, Co3O4, crystallizes only
in the sample with the higher cobalt content, while cobalt
silicate is the only crystalline phase detected in the sample
10Co and 20Co. Both the cobalt content and the temperature
of heat treatment resulted to affect the nature of
cobalt species dispersed in the silica matrix. The 30Co was
selected for further investigations by FTIR spectroscopy to
follow the structural evolution of 30Co film as function of
the temperature and UV–Vis to get information on the
cobalt valence state. The optical gas-sensing properties of
30Co films, containing Co3O4 as the major cobalt phase,
were studied through the measuring of the film transmittance
in dry air and in presence of dry air containing variable
concentrations of polluting gases, CO and NO2. The
30Co samples resulted to be highly sensitive to CO at room
temperature. An explanation for the CO sensing characteristics,
at low temperature, was proposed by referring to
the physisorption-related mechanics of CO
Arthroscopic surgery or exercise therapy for degenerative meniscal lesions: a systematic review of systematic reviews
Get PDFBackground: Arthroscopic partial meniscectomy (APM) is widely applied for the treatment of degenerative meniscal lesions in middle-aged patients; however, such injury is often associated with mild or moderate osteoarthritis and has been reported by MRI in asymptomatic knees. Previous studies suggested, in most patients, a lack of benefit of surgical approach over conservative treatment, yet many controversies remain in clinical practice. Our aims were to assess the functional and pain scores between exercise therapy and arthroscopic surgery for degenerative meniscal lesions and to evaluate the methodological quality of the most recent systematic reviews (SRs).Methods: Two authors independently searched PubMed and Google Scholar for SRs comparing the outcome (in knee pain and functionality) of arthroscopic treatment and exercise therapy or placebo for degenerative meniscal lesions. The timeframe set was from 2009 to 2019 included.Results: A total of 13 SRs were selected. Two reviewers independently assessed the methodological quality of each paper using the AMSTAR 2 tool: seven scored as "moderate," four obtained a "low" grade while the remaining two were evaluated as "critically low." SRs agreed that in middle-aged patients with degenerative meniscal lesions arthroscopic surgery appears to grant no long-term improvement in pain and function over exercise therapy or placebo.Conclusions: Conservative treatment based on physical therapy should be the first-line management. However, most SRs revealed subgroups of patients that fail to improve after conservative treatment and find relief when undergoing surgery. In the future, randomized controlled trials, evidence should be looked for that APM can be successful in case of the unsatisfactory results after physical therapy
Mason type III fractures of the radial head: ORIF, resection or prosthetic replacement?
No full textPurpose: This study focused on a comparison of mid-term clinical, functional and radiographic outcomes of adults treated by open reduction and internal fixation (ORIF), radial head prosthesis (RHP) and resection (RHR). Methods: The retrospective evaluation concerned 47 surgically treated patients after a mean follow-up of 53 months. All patients were grouped according to the surgical procedure performed: 15 in the RHP group, 16 in the ORIF group and 16 in the RHR group. At the follow-up, outcome assessment was based on radiographs, range of motion (ROM) and functional rating scores. Results: Patients treated by RHR had significantly higher mean age and shorter operation time than other two groups. Compared to ROM, flexion, extension and pronation were significantly worse in patients treated by ORIF than those in the RHP group and the RHR group. Supination was significantly better in the RHP group. However, no statistical differences were observed in functional rating scores among the three groups. Regarding complications, instability was the only cause of revision surgery in the RHP group and the RHR group. On the other hand, the ORIF group revision rate was 50% and secondary displacement was the most frequent cause of failure. Conclusion: The ORIF group did not show good results with greater elbow stiffness and higher revision rate than the other two techniques. RHR may be suitable for elderly patients with lower functional demands as it reported good clinical results and reduced operation time
Marine diatoms as optical biosensors
No full textWe have chemically modified the frustules of the marine diatom Coscinodiscus concinnus Wm. Smith to properly bind a highly selective bioprobe such as an antibody. By measuring the changes in the photoluminescence emission of diatoms frustules, we have monitored the molecular recognition event between the antibody and its ligand: the dissociation constant estimated is of the same order of that measured by standard Biacore®. The nanostructured silica frustules, a low-cost and natural available material, have shown high sensitivity, equal to 1.2 ± 0.2 nm μM-1, and a detection limit of 100 nM, and thus are quite ideal candidates for lab-on-particle applications. © 2008 Elsevier B.V. All rights reserved
Optical sensing of NO2 in tin oxide nanowires at sub-ppm level
No full textTin oxide nanostructures are currently considered as promising materials for gas sensing. Some of their physical properties, such as visible light photoluminescence, are still not fully understood and require further investigations. In this work we report on the quenching of tin oxide nanowires photoluminescence induced by nitrogen dioxide adsorption at the ppm and sub-ppm level. The recombination dynamics was investigated by means of time-resolved photoluminescence, finding non-exponential decay profiles. Neither the photoluminescence spectral shape nor the decay rates are found to depend significantly on the nitrogen dioxide concentration, suggesting that the gas-nanostructure interaction resides in a net reduction of the density of states which are responsible for the radiative transitions. (C) 2007 Elsevier B.V All rights reserved
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