1,720,969 research outputs found
Growing CeO2 Nanoparticles Within the Nano-Porous Architecture of the SiO2 Aerogel
Full text linkIn this study, new CeO2-SiO2 aerogel nanocomposites obtained by controlled growth of CeO2 nanoparticles within the highly porous matrix of a SiO2 aerogel are presented. The nanocomposites have been synthesized via a sol-gel route, employing cerium (III) nitrate as the CeO2 precursor and selected surfactants to control the growth of the CeO2 nanoparticles, which occurs during the supercritical drying of the aerogels. Samples with different loading of the CeO2 dispersed phase, ranging from 5 to 15%, were obtained. The nanocomposites showed the morphological features typical of the SiO2 aerogels such as open mesoporosity with surface area values up to 430 m2·g−1. TEM and XRD characterizations show that nanocrystals of the dispersed CeO2 nanophase grow within the aerogel already during the supercritical drying process, with particle sizes in the range of 3 to 5 nm. TEM in particular shows that the CeO2 nanoparticles are well-distributed within the aerogel matrix. We also demonstrate the stability of the nanocomposites under high temperature conditions, performing thermal treatments in air at 450 and 900°C. Interestingly, the CeO2 nanoparticles undergo a very limited crystal growth, with sizes up to only 7 nm in the case of the sample subjected to a 900°C treatment
Evaluation of hard tissue response around wider platform-switched implants.
Full text linkThe use of a narrower-diameter abutment over a larger-diameter implant platform has been shown to decrease peri-implant bone resorption. This technique, known as platform switching, shifts the implant-abutment microgap inward. The aim of this study was to examine whether shifting the microgap further inward by increasing the discrepancy between the implant platform and abutment diameter would result in a decrease in crestal bone loss. Ten patients requiring mandibular or maxillary implant restorations were included in this study. The inclusion criteria called for an alveolar crest thickness of at least 8.0 mm at the implant placement site. Fifteen Certain PREVAIL implants with a body diameter of 5.0 mm, an expanded platform feature with a maximum diameter of 5.8 mm at the collar, and a prosthetic seating surface of 5.0 mm were used in lengths of 8.5, 10.0, 11.5, or 13.0 mm. The implants were connected to 4.1-mm healing abutments in a single-stage protocol. Periapical radiographs taken before and immediately after surgery, 8 weeks after implant placement, immediately after definitive prosthesis insertion, and at 12 and 18 months after loading revealed an average peri-implant bone loss of 0.30 mm. Increasing the discrepancy between the diameter of the implant platform and the restorative abutment may lead to a decrease in the amount of subsequent coronal bone loss
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Squamous cell carcinoma of the oral cavity and hyperhomocysteinemia. There's a correlation? A preliminary study
No full textPurpose: The purpose of this study was to compare serum levels of HCY and Folate with SCCOC, in order to find statistically significant data showing that the correction of these levels might correspond to an improvement in conventional therapies. The Study also aims to highlight the possibility that Hyperhomocysteinemia (HHCY) could be considered as a tumoral marker. Materials and Methods: Serum levels of Folate and HCY were measured in 20 patients with histologically-proven SCCOC, before any treatment, and in 20 healty patients, non-smokers. These patients were subjected to nutritional control, with the supplementation of Folate (4 mg tablets, 1x2 for 6 months) aided by consumption of two kiwifruit a day. Checks were made at the beginning of therapy and after 1 month, 3 and six months. Results: At the first check, cancer patiens showed consistently high values, particularly those with low-grade carcinomas. These high values, at the end of the observation period, appeared much improved. Even the healty patients revealed clear improvements. Conclusions: The role of HCY and folates appears to be important in carcinogenesis of SCCOC, but these serum levels are still not a reference value, so they cannot be included among the known tumor markers. © 2015 Nova Science Publishers, Inc
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Podoplanin in the development and progression of oral cavity cancer: a preliminary study
Full text linkObjective. Podoplanin is a mucin-like glycoprotein that is important in lymphangiogenesis but not in blood vessel formation. The aim of this preliminary study is to determine the role of podoplanin in the development and progression of head and neck cancer.
Material and Methods.Podoplanin over expression was analyzed in 20 patients with oral cancer, by immunohistochemical analysis.
Result. Podoplanin is not expressed in normal oral epithelial cells but was found in some hyperplastic and dysplastic lesions. Podoplanin high expression was found in 9 of 20 patients and was more frequent in cancers with lymph node metastasis, particularly in oral cavity cancers. In our preliminary study, patients who showed high levels of podoplanin had a statistically greater rate of lymph node metastasis (P<0,001); patients with lymph node metastasis and high-level podoplanin showed a shorter disease-specific survival (P = 0,004) than other patients.
Conclusion. The results of our preliminary study have provided interesting and encouraging data. We have observed that podoplanin expression increases in the early stages of tumourigenesis and it seems to be associated with a higher risk of head and neck cancer. While in squamous cell carcinoma podoplanin expression diminishes during tumour progression. These data support a role for podoplanin expression in the initiation but not in the progression of cancer. So we can conclude that podoplanin is involved in oral oncogenesis and can be a predictor for lymph node metastasis in asymptomatic patients. Histology and podoplanin analysis can be very useful to predict the risk of development, invasion and metastatic progression of a tumour in patients with oral cancer
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