Search results for "silica"

Comparative Surface Morphology, Chemical Composition, and Cytocompatibility of Bio-C Repair, Biodentine, and ProRoot MTA on hDPCs

2020

Biocompatibility is an essential property for any vital pulp material that may interact with the dental pulp tissues. Accordingly, this study aimed to compare the chemical composition and ultrastructural morphology of Biodentine (Septodont, Saint Maur-des-Fosses, France), ProRoot MTA (Dentsply Tulsa Dental Specialties, Johnson City, TN, USA), and Bio-C Repair (Angelus, Londrina, PR, Brazil), as well as their biological effects on human dental pulp cells. Chemical element characterization of the materials was undertaken using scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDX). The cytotoxicity was assessed by analyzing the cell viability (MTT assay), cell morphology …

Evaluación del efecto de los selladores con base de biosilicatos en células madre de origen dental

2016

Objetivo: En esta tesis doctoral se investigó la biocompatibilidad in vitro de dos selladores endodónticos en base a silicato de calcio, MTA Fillapex y TotalFill BC Sealer, en las células madre del ligamento periodontal humano (hPDLSCs), comparando los resultados con un sellador a base de resina-epóxica (AH Plus). Metodología: Se utilizaron células madre del ligamento periodontal obtenidas de terceron molares sanos exodonciados. Se realizaron elusiones de los tres diferentes selladores endodónticos con medio de cultivo. La citotoxicidad de estas diluciones se evaluó usando el ensayo de MTT. Para determinar el efecto sobre la migración célular se utilizó un modelo in vitro de curación de her…

THE PHYSICAL ORIGIN OF PROTEIN DYNAMICAL TRANSITION: A LIQUID-LIQUID TRANSITION IN HYDRATION WATER?

2015

In this thesis I study, by means of neutron scattering, calorimetry, and dielectric spectroscopy, the physical origin of protein dynamical transition (PDT) which is usually observed at ~230 K in protein hydrated powders and is deemed necessary for protein function. Measurements reported in this thesis have been performed on hydrated powders of Myoglobin. The combined use of different experimental techniques gives a coherent description of the PDT and reveals a connection with a liquid-liquid crossover occurring in the protein hydration water at about the same temperature. In order to deepen our understanding of this connection and to obtain a direct experimental evidence of the existence of…

Effects of Pressure, Temperature, and Particles Size on O2 Diffusion Dynamics in Silica Nanoparticles

2013

The O2 diffusion process in silica nanoparticles is experimentally studied in samples of average radius of primary particles ranging from 3.5 to 20 nm and specific surface ranging from 50 to 380 (m2/g). The investigation is done in the temperature range from 98 to 177 °C at O2 pressure ranging from 0.2 to 66 bar by measuring the interstitial O2 concentration by Raman and photoluminescence techniques. The kinetics of diffusion can be described by the Fick’s equation with an effective diffusion coefficient depending on the temperature, O2 pressure, and particles size. In particular, the dependence of the diffusion coefficient on the pressure and nanoparticles size is more pronounced at lower …

Nano-Silica Carriers Coated by Chloramphenicol: Synthesis, Characterization, and Grinding Trial as a Way to Improve the Release Profile

2022

Silica nanoparticles were applied as the carrier of chloramphenicol (2,2-dichloro-N-[(1R,2R)-1,3-dihydroxy-1-(4-nitrophenyl)propan-2-yl]acetamide), and were loaded in a 1% carbopol-based gel (poly(acrylic acid)), which allowed obtainment of an upgraded drug form. The samples of silica materials were obtained by means of modified Stöber synthesis, and their morphological properties were analyzed using Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) method, elemental analysis (EA), thermogravimetric analysis (TGA), analysis of the specific surface properties, X-ray diffraction study (XRD), scanning electron microscope (SEM), and dynamic light scattering (DLS) meth…

P046 Occupational exposures and gastric cancer risk in the MCC-spain case-control study

2016

Objective To explore the relationship between gastric cancer (GC) and occupational exposures. Methods A total of 382 incident GC cases and 2,846 randomly selected population controls with occupational information were included from the MCC-Spain study, a population-based multicase-control study. Occupation was coded according to the Spanish National Classification of Occupations 1994. Occupational exposures were assessed by the MatEmEsp Job Exposure Matrix. ORs and their 95% confidence intervals (CI) were estimated by unconditional logistic regression adjusting for matching variables and education. Results In men, a statistically significant increased risk of GC, was found for ‘Employed ski…

EPOXY RESIN VS BIOCERAMIC: SYSTEMATIC REVIEW WITH META-ANALYSIS

2021

Eumelanin Coating of Silica Aerogel by Supercritical Carbon Dioxide Deposition of a 5,6-Dihydroxyindole Thin Film

2018

Eumelanin integration in silica aerogel (SA) was achieved via supercritical adsorption of 5,6-dyhydroxyindole (DHI) from CO2. Notably, after the supercritical treatment, DHI evolved towards spontaneous polymerization, which resulted in uniform pigment development over the SA. The new material was characterized for its morphological and physicochemical properties, disclosing the formation of a eumelanin-like coating, as confirmed by UV&ndash

Degassing of halogens from basaltic volcanism: Insights from volcanic gas observations

2009

Abstract The currently available data set of S–Cl–F abundances in volcanic gas plumes and high-temperature fumarolic gas samples from basaltic volcanism is reviewed here in the attempt to derive constraints on the modes of halogen degassing from mafic silicate melts. Apart from large volcano-to-volcano variations, reflecting remarkable differences in volatile abundances in the source magmas, each of the explored volcanoes displays large changes of SO2/HCl and SO2/HF ratios with the style of volcanic activity, with HCl/HF staying fairly constant. Halogen abundances are low and SO2/HCl and SO2/HF are high when fresh (volatile-rich) magmas sustain degassing, as during explosive eruptions, at t…

Spectroscopic Properties of Holmium-Aluminum- Germanium Co-doped Silica Fiber

2020

We report the basic spectroscopic properties of a home-made holmium-aluminum-germanium co-doped silica fiber, designed for laser applications. We present the ground-state and excitedstate absorption spectra of the fiber along with the upconversion emission spectrum under laser action, which served for making an energy levels’ diagram of Ho3+ ion. We discuss the ways to assess the kinetics of Ho3+ 2-μm fluorescence, focusing on measuring fluorescence lifetime from 5I7 level and nonradiative decay time from 5I6 level. The simple analytical formulae, applicable for fitting of the fluorescence decay curve, are derived, which can be useful for precise modeling of holmiumdoped fiber lasers. PID20…