Time filter

Source Type

Gerona, Spain

Frassetto A.,University of Trieste | Navarra C.O.,University of Trieste | Marchesi G.,University of Trieste | Turco G.,University of Trieste | And 5 more authors.
Dental Materials

Objectives: The aim of the study was to evaluate the contraction stress, microhardness and polymerization kinetics of three self-adhesive cements vs. conventional dual-cure resin cement. Methods: Cements tested were: RelyX Unicem (3M ESPE, St. Paul, MN, USA), MaxCem Elite (Kerr, Orange, CA, USA), Clearfil SA Cement (Kuraray, Tokyo, Japan) and Duolink (Bisco Inc., Schaumburg, IL, USA). Cements were irradiated with a LED-curing unit (bluephase, IvoclarVivadent) for 20 or 40 s and the contraction forces (N) generated during polymerization were continuously recorded for 6 h with a universal testing machine. Polymerization kinetics were monitored using micro-Raman spectroscopy and degree of conversion was calculated. Vickers microhardness was also recorded. All measurements were performed at 10 min and 6 h. Data were statistically analyzed by three-way ANOVA with repeated measures and Tukey's post hoc test (α = 0.05). Results: Irrespective of exposure time, stress analysis ranked in the following order: Clearfil SA Cement < MaxCem < RelyX Unicem ≤ Duolink (p < 0.05). Stress was correlated with microhardness values (p < 0.05). Kinetic curves showed that maximum degree of conversion was attained more quickly than maximum stress after light activation. Significance: The conventional resin-based cement showed higher stress values than the self-adhesive cements. The results were material-dependent and probably correlated to the composition of each material. © 2012 Academy of Dental Materials. Source

Basantes-Serrano R.,University Grenoble alpes | Basantes-Serrano R.,French National Center for Scientific Research | Rabatel A.,University Grenoble alpes | Rabatel A.,French National Center for Scientific Research | And 9 more authors.
Journal of Glaciology

In this paper, we reanalyze the glacier mass balance on Glaciar Antisana 15α over the 1995-2012 period. Annual glacier mass balances were quantified on the basis of monthly glaciological measurements using an adaptation of Lliboutry's statistical approach. The geodetic mass balance was computed between 1997 and 2009 giving a cumulative balance of -1.39 ± 1.97 m w.e. and a slightly negative adjusted annual glaciological mass balance (-0.12 ± 0.16 m w.e. a-1). Despite a careful analysis of uncertainties, we found a large discrepancy between the cumulative glaciological and the geodetic mass balances over the common period, of 4.66 m w.e. This discrepancy can mainly be explained by underestimated net accumulation in the glacier upper reaches, which could be due to the peculiar climate conditions of the equatorial zone with year round accumulation, thereby preventing clear identification of annual layers. An increase of ∼70% in measured rates of net accumulation would be needed to balance the glaciological and geodetic mass balances; a hypothesis confirmed by estimated ice flux in the vicinity of the ELA. Consequently, the vertical gradient of precipitation may be higher than previously estimated and the accumulation processes (including the role of frost deposition) need to be carefully analyzed. © The Author(s) 2016. Source

Saro C.,University of Leon | Ranilla M.J.,University of Leon | Ranilla M.J.,Igm Web Inc. | Cifuentes A.,CSIC - Mediterranean Institute for Advanced Studies | And 2 more authors.
Journal of Animal Science

The aim of this study was to compare automated ribosomal intergenic spacer analysis (ARISA) and denaturing gradient gel electrophoresis (DGGE) techniques to assess bacterial diversity in the rumen of sheep. Sheep were fed 2 diets with 70% of either alfalfa hay or grass hay, and the solid (SOL) and liquid (LIQ) phases of the rumen were sampled immediately before feeding (0 h) and at 4 and 8 h postfeeding. Both techniques detected similar differences between forages, with alfalfa hay promoting greater (P < 0.05) bacterial diversity than grass hay. In contrast, whereas ARISA analysis showed a decrease (P < 0.05) of bacterial diversity in SOL at 4 h postfeeding compared with 0 and 8 h samplings, no variations (P > 0.05) over the postfeeding period were detected by DGGE. The ARISA technique showed lower (P < 0.05) bacterial diversity in SOL than in LIQ samples at 4 h postfeeding, but no differences (P > 0.05) in bacterial diversity between both rumen phases were detected by DGGE. Under the conditions of this study, the DGGE was not sensitive enough to detect some changes in ruminal bacterial communities, and therefore ARISA was considered more accurate for assessing bacterial diversity of ruminal samples. The results highlight the influence of the fingerprinting technique used to draw conclusions on factors affecting ruminal bacterial diversity. © 2014 American Society of Animal Science. All rights reserved. Source

Colonna M.,University of Bologna | Breschi M.,University of Bologna | Mazzoni A.,University of Bologna | Mazzoni A.,Rizzoli Orthopaedic Institute | And 8 more authors.
Dental Materials

Objectives: The application of an electric field has been shown to positively influence the bonding of dentin bonding systems (DBS) by improving adhesive impregnation into dentin. However, the mechanism responsible for this phenomenon has not been completely elucidated. The aim of this study was to clarify the effects of pH, matrix ionic strength, and applied voltage on the migration of commonly used DBS monomers in a model matrix (agarose gel). Methods: Some common monomers examined were bis-GMA (2,2-bis[4-(2-hydroxy-3- methacryloyloxy propoxy) phenyl] propane); HEMA (2-hydroxyethyl methacrylate); 2-MP (bis[2-(methacryloyloxy) ethyl] phosphate); TCDM [di(hydroxyethyl methacrylate) ester of 5-(2,5,-dioxo tetrahydrofurfuryl)-3-methyl-3- cyclohexenyl-1,2-dicarboxylic acid]; and TEGDMA (triethylene glycol dimethacrylate). Agarose gels poured into a horizontal 10-well electrophoretic cell were used to mimic the collagen fibrils of the dentin organic matrix. The role of pH, matrix ionic strength, and voltage on monomer migration was assayed by modifying the experimental conditions. Results: Results of experiments performed at pH 3.1, 6.3, 8.5, and 12.3; at low, medium, and high ionic strength; and at 50 and 100 V clearly showed that DBA monomer migration toward both the anode and the cathode can be affected by each of these parameters. Significance: Migration of acrylic monomers toward the anode or cathode can be achieved as desired by selective choice of pH, ionic strength, and applied voltage. Additional studies are needed to evaluate the synergistic effects of DBS monomer blends on migration in an electric field. © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. Source

Mathew K.T.,Cochin University of Science and Technology | Kalappura U.G.,Cochin University of Science and Technology | Augustine R.,Igm Web Inc. | Jean-Marc L.,Igm Web Inc. | Lakshmi K.,Cochin University of Science and Technology
Microwave and Optical Technology Letters

Conducting polymers have found significant applications in the past decade in industrial, scientific, and medical (ISM) fields. The characteristic features of conducting polymers like reversible proton doping, variable conductivity, facile synthesis, and low cost make them potential candidates in various microelectronic applications. Conventional microwave absorbing materials such as carbon and graphite in the powder form were blended with polyaniline as base at different proportions and microwave properties such as transmission, reflection, and shielding efficiency (SE) were evaluated from S parameter measurements using HP 8714ET network analyzer. The newly developed polyaniline blend exhibits high-electromagnetic interference shielding efficiency when compared with previously developed materials and is a promising candidate for shielding applications. © 2009 Wiley Periodicals, Inc. Source

Discover hidden collaborations