Search results for " Silicate"
showing 10 items of 126 documents
Controlling the cohesion of cement paste
2005
The main source of cohesion in cement paste is the nanoparticles of calcium silicate hydrate (C-S-H), which are formed upon the dissolution of the original tricalcium silicate (C(3)S). The interaction between highly charged C-S-H particles in the presence of divalent calcium counterions is strongly attractive because of ion-ion correlations and a negligible entropic repulsion. Traditional double-layer theory based on the Poisson-Boltzmann equation becomes qualitatively incorrect in these systems. Monte Carlo (MC) simulations in the framework of the primitive model of electrolyte solution is then an alternative, where ion-ion correlations are properly included. In addition to divalent calciu…
Redox tuning and species distribution in Maya Blue-type materials: a reassessment.
2013
Maya Blue-type specimens prepared from indigo (1 wt %) plus kaolinite, montmorillonite, palygorskite, sepiolite, and silicalite are studied. Liquid chromatography with diode array detection, ultra-performance liquid chromatography coupled with mass spectrometry, and pyrolysis-silylation gas chromatography-mass spectrometry analyses of the extracts from these specimens combined with spectral and solid-state voltammetry, electrochemical impedance spectroscopy, and scanning electrochemical microscopy techniques provide evidence for the presence of a significant amount of dehydroindigo and isatin accompanying indigo and other minority organic compounds in all samples. Solid-state electrochemist…
Color change of the bleached enamel treated with calcium silicate- sodium phosphate-sodium monofluorophosphate-based system
2018
Background The increasing demand of tooth bleaching has also increased the need of researches focusing on the durability of the resultant color. The aim of this study was to evaluate the effect of a system based on calcium silicate, sodium phosphate and sodium monofluorophosphate (Regenerate™) on color maintenance of bleached enamel considering two waiting times for the contact with a cola drink. Material and Methods This in vitrostudy was performed on bovine enamel specimens (n = 100), bleached with 35% H2O2 and treated with: G1 Distilled water; G2 Artificial saliva; G3 RegenerateTM Serum and Toothpaste; G4 RegenerateTM Toothpaste; G5 RegenerateTM Serum. The groups G3, G4 and G5 received o…
Bioactivity Performance of Pure Mg after Plasma Electrolytic Oxidation in Silicate-Based Solutions
2021
The biodegradable metals, including magnesium (Mg), are a convenient alternative to permanent metals but fast uncontrolled corrosion limited wide clinical application. Formation of a barrier coating on Mg alloys could be a successful strategy for the production of a stable external layer that prevents fast corrosion. Our research was aimed to develop an Mg stable oxide coating using plasma electrolytic oxidation (PEO) in silicate-based solutions. 99.9% pure Mg alloy was anodized in electrolytes contained mixtures of sodium silicate and sodium fluoride, calcium hydroxide and sodium hydroxide. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), contact angle (CA), …
Dental stem cell signaling pathway activation in response to hydraulic calcium silicate-based endodontic cements: A systematic review of in vitro stu…
2020
Abstract Objective To present a qualitative synthesis of in vitro studies which analyzed human dental stem cell (DSC) molecular signaling pathway activation in response to hydraulic calcium silicate-based cements (HCSCs). Methods A systematic electronic search was performed in Medline, Scopus, Embase, Web of Science and SciELO databases on January 20 and last updated on March 20, 2020. In vitro studies assessing the implication of signaling pathways in activity related marker (gene/protein) expression and mineralization induced by HCSCs in contact with human DSCs were included. Results The search identified 277 preliminary results. After discarding duplicates, and screening of titles, abstr…
Magnesium silicate hydrate (M-S-H) characterization : temperature, calcium, aluminium and alkali
2017
The various options to store radioactive wastes in deep geological strata considered in France or Switzerland include the use of large volumes of cementitious materials for infrastructure in contact with argillaceous rocks. So-called low-pH binders were developed to minimize disruption to the surrounding rock by the alkaline plume. Studies conducted on the interaction zone between concrete and clay systematically highlighted the formation of magnesium silicate phases including magnesium silicate hydrate (M-S-H) at the interfaces, which can presently be modeled only partially due to incomplete thermodynamic data. The purpose of this study was to characterize these phases in temperature, alum…
Repair of bone defect by nano-modified white mineral trioxide aggregates in rabbit: a histopathological study
2014
Background: Many researchers have tried to enhance materials functions in different aspects of science using nano-modification method, and in many cases the results have been encouraging. To evaluate the histopathological responses of the micro-/nano-size cement-type biomaterials derived from calcium silicate-based composition with addition of nano tricalcium aluminate (3CaO.Al 2 O 3 ) on bone healing response. Material and Methods: Ninety mature male rabbits were anesthetized and a bone defect was created in the right mandible. The rabbits were divided into three groups, which were in turn subdivided into five subgroups with six animals each based on the defect filled by: white mineral tri…
Periodontal Treatment with an Er:YAG Laser or Scaling and Root Planing. A 2-Year Follow-Up Split-Mouth Study
2003
Non-surgical periodontal treatment with an Er:YAG laser has been shown to result in significant clinical attachment level gain; however, clinical results have not been established on a long-term basis following Er:YAG laser treatment. Therefore, the aim of the present study was to present the 2-year results following non-surgical periodontal treatment with an Er:YAG laser or scaling and root planing.Twenty patients with moderate to advanced periodontal destruction were treated under local anesthesia, and the quadrants were randomly allocated in a split-mouth design to either 1) Er:YAG laser (ERL) using an energy level of 160 mJ/pulse and 10 Hz, or 2) scaling and root planing (SRP) using han…
Aqueous Solubility Diagrams for Cementitious Waste Stabilization Systems. 4. A Carbonation Model for Zn-Doped Calcium Silicate Hydrate by Gibbs Energ…
2002
A thermodynamic Gibbs energy minimization (GEM) solid solution-aqueous solution (SSAS) equilibrium model was used to determine the solubility of Zn from calcium silicate hydrate (CSH) phases doped with 0, 0.1, 1, 5, and 10% Zn at a unity (Ca+Zn)/Si molar ratio. Both the stoichiometry and standard molar Gibbs energy (G(o)298) of the Zn-bearing end-member in the ideal ternary Zn-bearing calcium silicate hydrate (CZSH) solid solution were determined by a "dual-thermodynamic" (GEM-DT) estimation technique. The SSAS model reproduces a complex sequence of reactions suggested to occur in a long-term weathering scenario of cementitious waste forms at subsurface repository conditions. The GEM model …
Structural Investigation of K-Feldspar KAlSi3O8Crystals by XRD and Raman Spectroscopy: An Application to Petrological Study of Luc Yen Pegmatites, Ye…
2016
K-feldspars in pegmatites from Luc Yen gem mining area, Yen Bai province, Vietnam were studied by X-ray fluorescence, X-ray powder diffraction and the Raman spectroscopy. Chemical analysis determined the K-feldspars in the form of (K0:8909Na0:0388Ca0:002Pb0:0042Cs0:0024Rb0:0338)(Al0:9975Fe0:0053Ti0:0004)Si2:988O8. Both X-ray powder diffraction and Raman spectroscopy indicated Luc Yen K-feldspars as orthoclase phase. Together with the values of Al content of the T1 tetrahedral sites in orthoclase, it is understood that Luc Yen pegmatites are of young ages (Cenozoic) and shallow intrusive types.