Search results for " Silicate"

Multistep Crystallization Pathways in the Ambient‐Temperature Synthesis of a New Alkali‐Activated Binder

2021

Slow dynamics in ion-conducting sodium silicate melts: Simulation and mode-coupling theory

2005

A combination of molecular-dynamics (MD) computer simulation and mode-coupling theory (MCT) is used to elucidate the structure-dynamics relation in sodium-silicate melts (NSx) of varying sodium concentration. Using only the partial static structure factors from the MD as an input, MCT reproduces the large separation in relaxation time scales of the sodium and the silicon/oxygen components. This confirms the idea of sodium diffusion channels which are reflected by a prepeak in the static structure factors around 0.95 A^-1, and shows that it is possible to explain the fast sodium-ion dynamics peculiar to these mixtures using a microscopic theory.

Study of Uptake Mechanisms of Halloysite Nanotubes in Different Cell Lines

2021

Giuseppa Biddeci,1,2 Gaetano Spinelli,1 Marina Massaro,2 Serena Riela,2 Paola Bonaccorsi,3 Anna Barattucci,3 Francesco Di Blasi1 1Institute for Innovation and Biomedical Research (IRIB), CNR, Palermo, 90146, Italy; 2Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), Sect. Chemistry, University of Palermo, Palermo, 90128, Italy; 3Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, 98158, ItalyCorrespondence: Francesco Di BlasiInstitute for Innovation and Biomedical Research (IRIB), CNR, Via Ugo La Malfa 153, Palermo, 90146, ItalyTel +39 0916809514Email francesco.diblasi@irib.cnr.itPurpose: Hal…

Temperature and pressure dependence of quercetin-3-O-palmitate interaction with a model phospholipid membrane: film balance and scanning probe micros…

2004

The molecular interaction of quercetin-3-O-palmitate (QP) with dimyristoylphosphatidylcholine (DMPC) has been studied. Film balance measurements of the average molecular area vs QP molar fraction in DMPC/QP mixed monolayers showed that relevant positive deviations from ideality, i.e., a less dense monolayer packing, occurred for a temperature of 10 degrees C, below the critical melting transition temperature of DMPC monolayers T c m approximately equal 20 degrees C), while ideal behavior was observed at 37 degrees C, above this phase transition temperature. The positive deviation observed at low temperatures in the average molecular area increased with the surface pressure. Scanning probe m…

Geochemical Interactions of Plutonium with Opalinus Clay Studied by Spatially Resolved Synchrotron Radiation Techniques

2017

Plutonium plays an important role within nuclear waste materials because of its long half-life and high radiotoxicity. The aim of this study was to investigate with high spatial resolution the reactivity of the more oxidized forms of Pu(V,VI) within Opalinus Clay (OPA) rock, a heterogeneous, natural argillaceous rock considered as a potential repository host. A combination of synchrotron based X-ray microprobe and bulk techniques was used to study the spatial distribution and molecular speciation of Pu within OPA after diffusion and sorption processes. Microscopic chemical images revealed a pronounced impact of geochemical heterogeneities concerning the reactivity of the natural barrier mat…

Assessment of the interaction of Portland cement-based materials with blood and tissue fluids using an animal model

2016

Portland cement used in the construction industry improves its properties when wet. Since most dental materials are used in a moist environment, Portland cement has been developed for use in dentistry. The first generation material is mineral trioxide aggregate (MTA), used in surgical procedures, thus in contact with blood. The aim of this study was to compare the setting of MTA in vitro and in vivo in contact with blood by subcutaneous implantation in rats. The tissue reaction to the material was also investigated. ProRoot MTA (Dentsply) was implanted in the subcutaneous tissues of Sprague-Dawley rats in opposite flanks and left in situ for 3 months. Furthermore the material was also store…

Application of differently treated illite and illite clay samples for the development of ceramics

2017

Abstract This study represents the results of investigations on the possible geopolymer formation of an alkali, mechanically and thermally (including hydrothermally) activated 2:1 layer silicate, namely, illite and illite clay, for low-temperature ceramic products. The main starting materials were Quaternary illite clay samples taken from the Apriki–Laza pit in Latvia. For the investigations, an intermediate composition of illite clay and separated illite were used. The following research methods for the treated illite and illite clay were used: the phase transition was analysed by differential thermal analysis, while the phase compositions, microstructures and structures were analysed by X…

Clay-based drug-delivery systems: what does the future hold?

2017

Clays for drug delivery have been used from ancient time due to the large availability of clay minerals and their unprecedented properties. The empirical use of nanoclays from the past is converted in a stimulating scientific task aimed at building up nanoarchitectonic vehicles for drug delivery in a targeted and stimuli-responsive fashion. Here the historical aspects are discussed; next the modern examples of applications of different clay-based materials are discussed. A special focus is given to halloysite clay nanotubes, which are an emerging and very promising nanomaterial for drug-delivery purposes due to its special morphology and unique chemical properties. Advantages and limitatio…

Channel Formation and Intermediate Range Order in Sodium Silicate Melts and Glasses

2004

We use inelastic neutron scattering and molecular dynamics simulation to investigate the interplay between the structure and the fast sodium ion diffusion in various sodium silicates. With increasing temperature and decreasing density the structure factors exhibit an emerging prepeak around 0.9 A^-1. We show, that this prepeak has its origin in the formation of sodium rich channels in the static structure. The channels serve as preferential ion conducting pathways in the relative immobile Si-O matrix. On cooling below the glass transition this intermediate range order is frozen in.

Fracture Resistance of New Metal-Free Materials Used for CAD-CAM Fabrication of Partial Posterior Restorations

2020

Background and Objectives: To evaluate in vitro the fracture resistance and fracture type of computer-aided design and computer-aided manufacturing (CAD-CAM) materials. Materials and Methods: Discs were fabricated (10 &times