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Sung Hoon Hwang, Rouzbeh Shahsavari
Scaffolded porous submicron particles with well-defined diameter, shape and pore size have profound impacts in drug delivery, bone-tissue replacement, catalysis, sensors, photonic crystals and self-healing materials. However, understanding the interplay between pore size, particle size, and mechanical properties of such ultrafine particles, specially at the level of individual particles and their ensemble states, is a challenge. Herein, we focus on porous calcium-silicate submicron particles with various diameters - as a model system - and perform an extensive 900+ nanoindentations to completely map out their mechanical properties at three distinct structural forms from individual submicron particles to self-assembled ensembles to pressure-induced assembled arrays...
December 14, 2017: ACS Applied Materials & Interfaces
Jin Woo Jang, Oh Hyeon Kwon, Jun Sik Kim, Yuri Kim, Yong Soo Cho
A novel way of roughening the surface of a glass substrate using a carbon nanotube-driven template is introduced to enhance the white luminescence characteristics of a printed (Ba,Sr,Ca)2SiO4:Eu2+ yellow silicate phosphor layer. The distribution of closed pores in the template layer induces selective etching and micro-scale roughening. As a result, a substantial improvement of ∼22.5% in the luminous efficacy was achieved when both sides of the substrate were roughened. This is attributed to the reductions of both the total internal reflection of rays at the glass-air interface and the specular reflection at the phosphor-glass interface...
December 15, 2017: Optics Letters
Mariusz Lipski, Alicja Nowicka, Katarzyna Kot, Lidia Postek-Stefańska, Iwona Wysoczańska-Jankowicz, Lech Borkowski, Paweł Andersz, Anna Jarząbek, Katarzyna Grocholewicz, Ewa Sobolewska, Krzysztof Woźniak, Agnieszka Droździk
INTRODUCTION: This study aimed to evaluate the prognostic value of factors with regard to the treatment outcome of direct pulp capping using Biodentine (Septodont, Saint-Maur-des-Fossés, France), in permanent teeth in which the pulps were exposed during caries removal. METHODS: Between 2010 and 2014, 112 teeth with deep carious lesions underwent direct pulp capping. The patients were followed up at 2-3 months and 1-1.5 years with a routine examination on both recall visits...
December 12, 2017: Clinical Oral Investigations
Andrew G M Rankin, Paul B Webb, Daniel M Dawson, Jasmine Viger-Gravel, Brennan J Walder, Lyndon Emsley, Sharon E Ashbrook
Isotopic enrichment of 29Si and DNP-enhanced NMR spectroscopy are combined to determine the detailed surface structure of a silicated alumina catalyst. The significant sensitivity enhancement provided by DNP is vital to the acquisition of multinuclear and multidimensional experiments that provide information on the atomic-level structure of the species present at the surface. Isotopic enrichment not only facilitates spectral acquisition, particularly given the low (1.5 wt %) Si loading, but also enables spectra with higher resolution than those acquired using DNP to be obtained...
October 19, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
L Medvecky, R Stulajterova, M Giretova, J Mincik, M Vojtko, J Balko, J Briancin
OBJECTIVES: To investigate the tubule occlusion and remineralization potential of a novel toothpaste with active tetracalcium phosphate/monetite mixtures under de/remineralization cycling. METHODS: Dentin de/remineralization cycling protocol consisted of demineralization in 1% citric acid at pH 4.6 with following remineralization with toothpastes and soaking in artificial saliva. Effectiveness of toothpastes to promote remineralization was evaluated by measurement of microhardness recovery, analysis of surface roughness, thickness of coating and scanning electron microscopy...
December 9, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
Gregori M Kurtzman, Chess Moore
No abstract text is available yet for this article.
May 2017: Dentistry Today
Valentina Erastova, Matteo T Degiacomi, Donald G Fraser, H Chris Greenwell
Some seventy years ago, John Desmond Bernal proposed a role for clays in the origin of life. While much research has since been dedicated to the study of silicate clays, layered double hydroxides, believed to be common on the early Earth, have received only limited attention. Here we examine the role that layered hydroxides could have played in prebiotic peptide formation. We demonstrate how these minerals can concentrate, align and act as adsorption templates for amino acids, and during wetting-drying cycles, promote peptide bond formation...
December 11, 2017: Nature Communications
David Santamaria-Perez, Javier Ruiz-Fuertes, Tomas Marqueño, Julio Pellicer-Porres, Raquel Chulia-Jordan, Simon MacLeod, Catalin Popescu
We report on high-pressure and high-temperature angle-dispersive synchrotron X-ray diffraction and high-pressure Raman data up to 27 GPa and 700 K for natural silicate carbonate Ca5(SiO4)2(CO3) spurrite mineral. No phase transition was found in the studied P-T range. The room-temperature bulk modulus of spurrite using Ne as the pressure-transmitting medium is B0 = 77(1) GPa with a first-pressure derivative of B0' = 5.9(2). The structure compression is highly anisotropic, the b axis being approximately 30% more compressible than the a and c axes...
December 11, 2017: Inorganic Chemistry
D J Srivastava, P Florian, J H Baltisberger, P J Grandinetti
The dependence of a 29Si geminal J coupling across the inter-tetrahedral linkage on local structure was examined using first-principles DFT calculations. The two main influences on 2JSi-O-Si were found to be a primary dependence on the linkage Si-O-Si angle and a secondary dependence on mean Si-O-Si linkage of the two coupled 29Si nuclei. An analytical expression describing these dependences was proposed and used to develop an approach for relating the correlated pair of 2JSi-O-Si coupling and mean 29Si isotropic chemical shift to the linkage Si-O-Si angle and the mean Si-O-Si angle of the two coupled 29Si nuclei...
December 11, 2017: Physical Chemistry Chemical Physics: PCCP
Dipta B Ghosh, Bijaya B Karki
Carbon dioxide, generally considered as the second most abundant volatile component in silicate magmas, is expected to significantly influence various melt properties. In particular, our knowledge about its dynamical effects is lacking over most of Earth's mantle pressure regime. Here, we report the first-principles molecular dynamics results on the transport properties of carbonated MgSiO3 liquid under conditions of mantle relevance. They show that dissolved CO2 systematically enhances the diffusion rates of all elements and lowers the melt viscosity on average by factors of 1...
December 2017: Science Advances
Yeliz Guven, Sermin Dicle Aksakal, Nilufer Avcu, Gulcan Unsal, Elif Bahar Tuna, Oya Aktoren
Objective: The aim of this study was to evaluate and compare, both clinically and radiographically, the effects of calcium silicate-based materials (i.e., ProRoot MTA [PR-MTA], MTA-Plus [MTA-P], and Biodentine [BD]) and ferric sulfate [FS] in pulpotomy of primary molars. Materials and Methods: In this randomized clinical trial, 29 healthy 5- to 7-year-old children with at least four carious primary molars with no clinical or radiographic evidence of pulp degeneration were enrolled...
2017: BioMed Research International
Jardel Camilo do Carmo Monteiro, Mateus Rodrigues Tonetto, Matheus Coêlho Bandeca, Alvaro Henrique Borges, José Cláudio Martins Segalla, Keren Cristina Fagundes Jordão-Basso, Cristian Fernando Sanchez-Puetate, Milton Carlos Kuga
Teeth with furcal perforation present difficult resolution and dubious prognosis. Several materials have been proposed and calcium silicate-based cements such as mineral trioxide aggregate (MTA) are the most recommended. However, its long-term clinical behavior still remains poorly understood. The present study reports a clinical case of furcal perforation repair using Angelus MTA, with a 7-year follow-up. Patient sought treatment 2 months after iatrogenic accident. First lower right molar presented clinical signs such as fistula and bone loss between mesial and distal roots...
2017: Iranian Endodontic Journal
Fatemeh Dibaji, Elahe Mohammadi, Farzaneh Farid, Fatemeh Mohammadian, Pegah Sarraf, Mohammad Javad Kharrazifard
Introduction: Dentinal canal walls are in direct contact with endodontic sealers prior to post space preparation and luting cements after post space preparation. This direct contact may affect the bond strength of intraradicular posts to root dentin. This study aimed to assess the effect of three different sealers on the bond strength of fiber posts to root dentin. Methods and Materials: The canals of 56 extracted single-rooted human premolars after selection and decoronation were prepared...
2017: Iranian Endodontic Journal
Farnaz Jafari, Sanaz Jafari, Paria Etesamnia
An ideal endodontic sealer should have many properties such as excellent seal after setting, dimensional stability, slow setting time to ensure sufficient working time, insolubility to tissue fluids, adequate adhesion with canal walls and biocompatibility. Genotoxicity is one of the important factors that influence biocompatibility of an endodontic sealer. This literature review was conducted to survey the genotoxicity, bioactivity and clinical perspectives of calcium silicate based sealers. We searched PubMed using appropriate MeSH keywords...
2017: Iranian Endodontic Journal
Han Li, Wenhua Xiao, Panpan Xie, Liangyu Zheng
Herein we established co-immobilized methods for enoate reductases (ERs) and glucose dehydrogenase (GDH), forming a cofactor regeneration system. In cross-linked enzyme aggregates (CLEAs), ammonium sulfate and oxidized dextran were selected as a precipitant and a cross-linker, respectively. In biomimetic immobilization (BI), ER-GDH-silica particles (ER-GDH-SPs) were rapidly formed through a one-step approach by using a silicic acid precursor. Under the optimal conditions, the ER activity recovery in ER-GDH-CLEAs and ER-GDH-SPs were 44...
February 2018: Enzyme and Microbial Technology
Tibor Sopcak, Lubomir Medvecky, Maria Giretova, Radoslava Stulajterova, Juraj Durisin
Bone cements based on magnesium phosphates such as newberyite (N; MgHPO4.3H2O) have been shown as potential bone substitutes due to their biocompatibility, biodegradability and ability to support osteoblast differentiation and proliferation. Newberyite can hydrolyze to hydrated magnesium phosphate compounds (e.g. bobierite (Mg3(PO4)2.8H2O)) at alkaline conditions. In this study, 25 and 50 wt% of crystalline β -wollastonite (woll; CaSiO3) was admixed to newberyite powder in order to both enhance the acid-base hydrolysis of newberyite and to produce a functional bone cement...
January 1, 2017: Journal of Biomaterials Applications
Xuefang Chen, Ying Huang, Kaichuang Zhang
A novel type of cobalt nanofibers coated with layered nickel silicate (Co nanofibers @ voids @ Ni3Si2O5(OH)4) coaxial core-shell composites were successfully prepared via a well-known Stöber process and two hydrothermal methods. In the composites, the international nanosheet structure of the nickel silicate provided interlayer spaces for lithium ions in the process of insertion and extraction. The cobalt nanofibers served as a mechanical support for the nickel silicate nanosheets, which increased the electrical conductivity of the whole electrode...
December 5, 2017: Journal of Colloid and Interface Science
Bernhard C Stoeckle, Sebastian Beggel, Alexander F Cerwenka, Elena Motivans, Ralph Kuehn, Juergen Geist
The use of environmental DNA (eDNA) to determine the presence and distribution of aquatic organisms has become an important tool to monitor and investigate freshwater communities. The successful application of this method in the field, however, is dependent on the effectiveness of positive DNA verification, which is influenced by site-specific environmental parameters. Factors affecting eDNA concentrations in aquatic ecosystems include flow conditions, and the presence of substances that possess DNA-binding properties or inhibitory effects...
2017: PloS One
Sylvain Petitgirard, Wim J Malfait, Baptiste Journaux, Ines E Collings, Eleanor S Jennings, Ingrid Blanchard, Innokenty Kantor, Alexander Kurnosov, Marine Cotte, Thomas Dane, Manfred Burghammer, David C Rubie
The convection or settling of matter in the deep Earth's interior is mostly constrained by density variations between the different reservoirs. Knowledge of the density contrast between solid and molten silicates is thus of prime importance to understand and model the dynamic behavior of the past and present Earth. SiO_{2} is the main constituent of Earth's mantle and is the reference model system for the behavior of silicate melts at high pressure. Here, we apply our recently developed x-ray absorption technique to the density of SiO_{2} glass up to 110 GPa, doubling the pressure range for such measurements...
November 24, 2017: Physical Review Letters
Rylan Terry, Daniel Vinton, Colin McMillen, Joseph Kolis
A new structural member of the broad class of A3RESi6O15 compounds has been discovered for the formula Cs3RESi6O15, where RE = Dy-Lu,Y,In. The structure is unusual in that it contains octahedrally coordinated rare earth ions whose relative orientation dictates the structure as they rotate about the c-axis supported by the cyclic Si6O15 framework. The repeat unit of the rotation is eight units generating a very long, ~57 Å, unit cell axis. This unusual repeat unit is created by the structural flexibility of the hexasilicate ring, which is in turn affected by the size of the rare earth ion as well as the size of alkali ion residing within the silicate layers...
December 7, 2017: Angewandte Chemie
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