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https://www.readbyqxmd.com/read/29771113/crystal-chemical-substitution-at-ca-and-la-sites-in-cala-4-sio-4-3-o-to-design-the-composition-ca-1-x-m-x-la-4-x-re-x-sio-4-3-o-for-nuclear-waste-immobilization-and-its-influence-on-the-thermal-expansion-behavior
#1
Ramya Ravikumar, Buvaneswari Gopal, Hrudananda Jena
The oxysilicate apatite host CaLa4 (SiO4 )3 O has been explored for immobilization of radioactive nuclides. Divalent ion, trivalent rare earth ion, and combined ionic substitutions in the silicate oxyapatite were carried out to optimize the simulated wasteform composition. The phases were characterized by powder X-ray diffraction, FT-IR, TGA, SEM-EDS, and HT-XRD techniques. The results revealed the effect of ionic substitutions on the structure and thermal expansion behavior. The investigation resulted in the formulation of simulated wasteforms such as La3...
May 17, 2018: Inorganic Chemistry
https://www.readbyqxmd.com/read/29752095/synergistic-effect-of-strontium-and-silicon-in-strontium-substituted-sub-micron-bioactive-glass-for-enhanced-osteogenesis
#2
Wen Zhang, Deqiu Huang, Fujian Zhao, Wendong Gao, Luyao Sun, Xian Li, Xiaofeng Chen
Strontium-substituted sub-micron bioactive glasses (Sr-SBG) have been reported to have enhanced osteogenic differentiation capacity compared to sub-micron bioactive glasses (SBG) in our previous study. However, the underlying molecular mechanisms of such beneficial effect of Sr-SBG are still not fully understood. In this study, we synthesized Sr-SBG, studied the effects of Sr-SBG on proliferation and osteogenic differentiation of mouse mesenchymal stem cells (mMSCs), and identified the molecular mechanisms of the enhancement effect of Sr-SBG on mMSCs...
August 1, 2018: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/29658010/impact-of-intrinsic-structural-properties-on-the-hydration-of-2-1-layer-silicates
#3
Florian Schnetzer, Cliff T Johnston, Gnanasiri S Premachandra, Nicolas Giraudo, Rainer Schuhmann, Peter Thissen, Katja Emmerich
Several 2:1 layer silicates comprising di- and trioctahedral smectites of different layer charge between 0.2 and 0.4 per formula unit and a trioctahedral vermiculite were studied by an in situ method that allowed Fourier transform infrared spectroscopy (FTIR) spectra and water vapor sorption isotherms to be obtained simultaneously. The particle size and shape of the selected materials were determined using X-ray diffraction and gas adsorption analyses, which provided an estimate of the particle size with resulting edge site proportion...
December 21, 2017: ACS Earth & Space Chemistry
https://www.readbyqxmd.com/read/29620030/the-vanadate-garnet-ca-2-nacd-2-v-3-o-12-a-single-crystal-x-ray-diffraction-study
#4
Makoto Tokuda, Akira Yoshiasa, Tsutomu Mashimo, Kazuake Iishi, Akihiko Nakatsuka
Single crystals of the vanadate garnet Ca2 NaCd2 V3 O12 (dicalcium sodium dicadmium trivanadate) were synthesized using the floating-zone method and the crystal structure was investigated using single-crystal X-ray diffraction. We considered the effectiveness of substitution of the Y-site cation with reference to previous structural studies of vanadate garnets. The structures of vanadate garnets are subject to geometric constraints similar to those of silicate garnets. These constraints force the tetrahedral-dodecahedral shared edge length in vanadate garnets to become shorter than the unshared dodecahedral edge length, as in ugrandite (uvarovite, grossular and andradite) garnets...
April 1, 2018: Acta Crystallographica. Section C, Structural Chemistry
https://www.readbyqxmd.com/read/29550068/lead-extraction-and-glass-ceramics-synthesis-from-waste-cathode-ray-tube-funnel-glass-through-cooperative-smelting-process-with-coal-fly-ash
#5
Jianfang Lv, Hongying Yang, Zhenan Jin, Minglei Zhao
In this study, a novel process was developed for extracting lead from the hazardous waste cathode ray tube (CRT) funnel glass and simultaneously producing glass-ceramics. CRT funnel glass was mixed with coal fly ash and subjected to carbon thermal reduction with the addition of CaO. The homogeneous glass melt and reduced metallic lead were quenched in water. Glass-ceramics were produced from the parent glass through an appropriate heat treatment. The optimum carbon loading amount (calculated as the molar ratio of C/PbO), CaO/SiO2 ratio, smelting temperature and holding time for lead recovery were 1...
March 14, 2018: Waste Management
https://www.readbyqxmd.com/read/29495498/bioactive-glass-ceramic-foam-scaffolds-from-inorganic-gel-casting-and-sinter-crystallization
#6
Hamada Elasyed, Acacio Rincon Romero, Giulia Molino, Chiara Vitale Brovarone, Enrico Bernardo
Highly porous bioactive glass-ceramic scaffolds were effectively fabricated by an inorganic gel casting technique, based on alkali activation and gelification, followed by viscous flow sintering. Glass powders, already known to yield a bioactive sintered glass-ceramic (CEL2) were dispersed in an alkaline solution, with partial dissolution of glass powders. The obtained glass suspensions underwent progressive hardening, by curing at low temperature (40 °C), owing to the formation of a C-S-H (calcium silicate hydrate) gel...
February 27, 2018: Materials
https://www.readbyqxmd.com/read/29372528/hydration-of-dicalcium-silicate-and-diffusion-through-neo-formed-calcium-silicate-hydrates-at-weathered-surfaces-control-the-long-term-leaching-behaviour-of-basic-oxygen-furnace-bof-steelmaking-slag
#7
Douglas I Stewart, Andrew W Bray, Gideon Udoma, Andrew J Hobson, William M Mayes, Mike Rogerson, Ian T Burke
Alkalinity generation and toxic trace metal (such as vanadium) leaching from basic oxygen furnace (BOF) steel slag particles must be properly understood and managed by pre-conditioning if beneficial reuse of slag is to be maximised. Water leaching under aerated conditions was investigated using fresh BOF slag at three different particle sizes (0.5-1.0, 2-5 and 10 × 10 × 20 mm blocks) and a 6-month pre-weathered block. There were several distinct leaching stages observed over time associated with different phases controlling the solution chemistry: (1) free-lime (CaO) dissolution (days 0-2); (2) dicalcium silicate (Ca2 SiO4 ) dissolution (days 2-14) and (3) Ca-Si-H and CaCO3 formation and subsequent dissolution (days 14-73)...
April 2018: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/29314507/improved-photoactivity-of-pyroxene-silicates-by-cation-substitutions
#8
Merid Legesse, Heesoo Park, Fedwa El Mellouhi, Sergey N Rashkeev, Sabre Kais, Fahhad H Alharbi
We investigated the possibility of band structure engineering of pyroxene silicates with chemical formula A+1 B+3 Si2 O6 by proper cation substitution. Typically, band gaps of naturally formed pyroxene silicates such as NaAlSi2 O6 are quite high (≈5 eV). Therefore, it is important to find a way to reduce band gaps for these materials below 3 eV to make them usable for optoelectronic applications operating at visible light range of the spectrum. Using first-principles calculations, we found that appropriate substitutions of both A+ and B3+ cations can reduce the band gaps of these materials to as low as 1...
January 4, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29282550/bioactive-calcium-silicate-poly-%C3%AE%C2%B5-caprolactone-composite-scaffolds-3d-printed-under-mild-conditions-for-bone-tissue-engineering
#9
Yen-Hong Lin, Yung-Cheng Chiu, Yu-Fang Shen, Yuan-Haw Andrew Wu, Ming-You Shie
The present study provides a solvent-free processing method for establishing the ideal porous 3-dimension (3D) scaffold filled with different ratios of calcium silicate-based (CS) powder and polycaprolactone (PCL) for 3D bone substitute application. Characterization of hybrid scaffolds developed underwent assessments for physicochemical properties and biodegradation. Adhesion and growth of human Wharton's Jelly mesenchymal stem cells (WJMSCs) on the CS/PCL blended scaffold were investigated in vitro. Cell attachment and morphology were examined by scanning electron microscope (SEM) and confocal microscope observations...
December 27, 2017: Journal of Materials Science. Materials in Medicine
https://www.readbyqxmd.com/read/29224421/hydrolysis-setting-properties-and-in-vitro-characterization-of-wollastonite-newberyite-bone-cement-mixtures
#10
Tibor Sopcak, Lubomir Medvecky, Maria Giretova, Radoslava Stulajterova, Juraj Durisin
Bone cements based on magnesium phosphates such as newberyite (N; MgHPO4 .3H2 O) 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 .8H2 O)) 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...
February 2018: Journal of Biomaterials Applications
https://www.readbyqxmd.com/read/29197578/magnesium-based-bioceramics-in-orthopedic-applications
#11
REVIEW
Maryam Nabiyouni, Theresa Brückner, Huan Zhou, Uwe Gbureck, Sarit B Bhaduri
Magnesium ions are directly involved in numerous biological mechanisms; for example, they play an important part in the regulation of ion channels, DNA stabilization, enzyme activation and stimulation of cell growth and proliferation. This alkaline earth metal has gained great popularity in orthopedic applications in recent years. Magnesium-based bioceramics include a large group of magnesium containing compounds such as oxides, phosphates and silicates, that are involved in orthopedic applications like bone cements, bone scaffolds or implant coatings...
January 15, 2018: Acta Biomaterialia
https://www.readbyqxmd.com/read/29186932/ionic-substitutions-in-non-apatitic-calcium-phosphates
#12
REVIEW
Aleksandra Laskus, Joanna Kolmas
Calcium phosphate materials (CaPs) are similar to inorganic part of human mineralized tissues (i.e., bone, enamel, and dentin). Owing to their high biocompatibility, CaPs, mainly hydroxyapatite (HA), have been investigated for their use in various medical applications. One of the most widely used ways to improve the biological and physicochemical properties of HA is ionic substitution with trace ions. Recent developments in bioceramics have already demonstrated that introducing foreign ions is also possible in other CaPs, such as tricalcium phosphates (amorphous as well as α and β crystalline forms) and brushite...
November 27, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29070160/bioactive-tricalcium-silicate-based-dentin-substitute-as-an-indirect-pulp-capping-material-for-primary-teeth-a-12-month-follow-up
#13
Arturo Garrocho-Rangel, Karina Quintana-Guevara, Rocío Vázquez-Viera, Juana María Arvizu-Rivera, Héctor Flores-Reyes, Diana María Escobar-García, Amaury Pozos-Guillén
PURPOSE: The purpose of this study was to evaluate the clinical and radiographic outcomes of a bioactive tricalcium silicate [Ca3SiO5]-based dentin substitute and a light-activated calcium hydroxide [Ca(OH)2]-based liner as indirect pulp treatment (IPT) interventions for vital primary molars with carious lesions approaching the pulp. METHODS: Eighty children, aged four to eight years old, with 160 bilateral primary teeth without signs or symptoms of irreversibly inflamed or degenerative pulp tissue were treated in a split-mouth design trial comparing IPT using Ca3SiO5 or Ca(OH)2...
September 15, 2017: Pediatric Dentistry
https://www.readbyqxmd.com/read/29020507/custom-repair-of-mandibular-bone-defects-with-3d-printed-bioceramic-scaffolds
#14
H Shao, M Sun, F Zhang, A Liu, Y He, J Fu, X Yang, H Wang, Z Gou
Implanting artificial biomaterial implants into alveolar bone defects with individual shape and appropriate mechanical strength is still a challenge. In this study, bioceramic scaffolds, which can precisely match the mandibular defects in macro and micro, were manufactured by the 3-dimensional (3D) printing technique according to the computed tomography (CT) image. To evaluate the stimulatory effect of the material substrate on bone tissue regeneration in situ in a rabbit mandibular alveolar bone defect model, implants made with the newly developed, mechanically strong ~10% Mg-substituted wollastonite (Ca90% Mg10% SiO3 ; CSi-Mg10) were fabricated, implanted into the bone defects, and compared with implants made with the typical Ca-phosphate and Ca-silicate porous bioceramics, such as β-tricalcium phosphate (TCP), wollastonite (CaSiO3 ; CSi), and bredigite (Bred)...
January 2018: Journal of Dental Research
https://www.readbyqxmd.com/read/28895273/protecting-and-leaving-functions-of-trimethylsilyl-groups-in-trimethylsilylated-silicates-for-the-synthesis-of-alkoxysiloxane-oligomers
#15
Masashi Yoshikawa, Yasuhiro Tamura, Ryutaro Wakabayashi, Misa Tamai, Atsushi Shimojima, Kazuyuki Kuroda
The concept of protecting groups and leaving groups in organic synthesis was applied to the synthesis of siloxane-based molecules. Alkoxy-functionalized siloxane oligomers composed of SiO4 , RSiO3 , or R2 SiO2 units were chosen as targets (R: functional groups, such as Me and Ph). Herein we describe a novel synthesis of alkoxysiloxane oligomers based on the substitution reaction of trimethylsilyl (TMS) groups with alkoxysilyl groups. Oligosiloxanes possessing TMS groups were reacted with alkoxychlorosilane in the presence of BiCl3 as a catalyst...
September 12, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28869882/the-utilization-of-waste-by-products-for-removing-silicate-from-mineral-processing-wastewater-via-chemical-precipitation
#16
Jianhua Kang, Wei Sun, Yuehua Hu, Zhiyong Gao, Runqing Liu, Qingpeng Zhang, Hang Liu, Xiangsong Meng
This study investigates an environmentally friendly technology that utilizes waste by-products (waste acid and waste alkali liquids) to treat mineral processing wastewater. Chemical precipitation is used to remove silicate from scheelite (CaWO4) cleaning flotation wastewater and the waste by-products are used as a substitute for calcium chloride (CaCl2). A series of laboratory experiments is conducted to explain the removal of silicate and the characterization and formation mechanism of calcium silicate. The results show that silicate removal reaches 90% when the Ca:Si molar ratio exceeds 1...
November 15, 2017: Water Research
https://www.readbyqxmd.com/read/28866158/use-of-a-fluorescent-probe-to-monitor-the-enhanced-affinity-of-rh-bmp-2-to-silicated-calcium-phosphate-synthetic-bone-graft-substitutes-under-competitive-conditions
#17
Marc-Krystelle Mafina, Alice C Sullivan, Karin A Hing
A comparative investigation was undertaken on 1-2mm sized granules of two forms of synthetic bone graft substitute (SBG) with identical pore structure but varied bulk chemistry, stoichiometric hydroxyapatite (HA) and silicate substituted (0.8wt% Si) hydroxyapatite (SA), to assess the influence of SBG chemistry on the relative affinity of an osteogenic growth factor (GF), recombinant human bone morphogenetic protein-2 (rhBMP-2). A previously described novel fluorescent probe, fluoresceinthioureidoaminocaproic acid (FTCA), was covalently attached to rhBMP-2 to give FTCA-rhBMP-2 and facilitate the quantitative monitoring of GF uptake and release from the two chemistries of SBG...
November 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28773119/a-new-biphasic-dicalcium-silicate-bone-cement-implant
#18
Fausto Zuleta, Angel Murciano, Sergio A Gehrke, José E Maté-Sánchez de Val, José L Calvo-Guirado, Piedad N De Aza
This study aimed to investigate the processing parameters and biocompatibility of a novel biphasic dicalcium silicate (C₂S) cement. Biphasic α´L + β-C₂Sss was synthesized by solid-state processing, and was used as a raw material to prepare the cement. In vitro bioactivity and biocompatibility studies were assessed by soaking the cement samples in simulated body fluid (SBF) and human adipose stem cell cultures. Two critical-sized defects of 6 mm Ø were created in 15 NZ tibias. A porous cement made of the high temperature forms of C₂S, with a low phosphorous substitution level, was produced...
July 6, 2017: Materials
https://www.readbyqxmd.com/read/28772513/doped-calcium-silicate-ceramics-a-new-class-of-candidates-for-synthetic-bone-substitutes
#19
REVIEW
Young Jung No, Jiao Jiao Li, Hala Zreiqat
Doped calcium silicate ceramics (DCSCs) have recently gained immense interest as a new class of candidates for the treatment of bone defects. Although calcium phosphates and bioactive glasses have remained the mainstream of ceramic bone substitutes, their clinical use is limited by suboptimal mechanical properties. DCSCs are a class of calcium silicate ceramics which are developed through the ionic substitution of calcium ions, the incorporation of metal oxides into the base binary xCaO-ySiO₂ system, or a combination of both...
February 10, 2017: Materials
https://www.readbyqxmd.com/read/28772490/effects-of-incorporating-high-volume-fly-ash-into-tricalcium-silicate-on-the-degree-of-silicate-polymerization-and-aluminum-substitution-for-silicon-in-calcium-silicate-hydrate
#20
Sungchul Bae, Rae Taylor, David Kilcoyne, Juhyuk Moon, Paulo J M Monteiro
This study assesses the quantitative effects of incorporating high-volume fly ash (HVFA) into tricalcium silicate (C₃S) paste on the hydration, degree of silicate polymerization, and Al substitution for Si in calcium silicate hydrate (C-S-H). Thermogravimetric analysis and isothermal conduction calorimetry showed that, although the induction period of C₃S hydration was significantly extended, the degree of hydration of C₃S after the deceleration period increased due to HVFA incorporation. Synchrotron-sourced soft X-ray spectromicroscopy further showed that most of the C₃S in the C₃S-HVFA paste was fully hydrated after 28 days of hydration, while that in the pure C₃S paste was not...
February 4, 2017: Materials
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