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https://www.readbyqxmd.com/read/29314507/improved-photoactivity-of-pyroxene-silicates-by-cation-substitutions
#1
Merid Legesse Belayneh, 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+1B+3Si2O6 by proper cation substitution. Typically, bandgaps of naturally formed pyroxene silicates such as NaAlSi2O6 are quite high (~5 eV). Therefore, it is important to find a way to reduce bandgaps 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 bandgaps 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
#2
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%C3%A2-vitro-characterization-of-wollastonite-newberyite-bone-cement-mixtures
#3
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
https://www.readbyqxmd.com/read/29197578/magnesium-based-bioceramics-in-orthopedic-applications
#4
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...
November 29, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/29186932/ionic-substitutions-in-non-apatitic-calcium-phosphates
#5
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
#6
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
#7
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)...
October 1, 2017: 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
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
https://www.readbyqxmd.com/read/28753001/stabilization-of-lithium-transition-metal-silicates-in-the-olivine-structure
#14
Xiaoqi Sun, Rajesh Tripathi, Guerman Popov, Mahalingam Balasubramanian, Linda F Nazar
While olivine LiFePO4 shows amongst the best electrochemical properties of Li-ion positive electrodes with respect to rate behavior owing to facile Li(+) migration pathways in the framework, replacing the [PO4](3-) polyanion with a silicate [SiO4](4-) moiety in olivine is desirable. This could allow additional alkali content and hence electron transfer, and increase the capacity. Herein we explore the possibility of a strategy toward new cathode materials and demonstrate the first stabilization of a lithium transition metal silicate (as a pure silicate) in the olivine structure type...
July 28, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28680554/characterization-and-antimicrobial-efficacy-of-portland-cement-impregnated-with-silver-nanoparticles
#15
Ki Young Nam
PURPOSE: This study investigated the effects of silver nanoparticle (SN) loading into hydraulic calcium silicate-based Portland cement on its mechanical, antibacterial behavior and biocompatibility as a novel dental bone substitute. MATERIALS AND METHODS: Chemically reduced colloidal SN were combined with Portland cement (PC) by the concentrations of 0 (control), 1.0, 3.0, and 5.0 wt%. The physico-mechanical properties of silver-Portland cement nanocomposites (SPNC) were investigated through X-ray diffraction (XRD), setting time, compressive strength, solubility, and silver ion elution...
June 2017: Journal of Advanced Prosthodontics
https://www.readbyqxmd.com/read/28678157/an-injectable-glass-polyalkenoate-cement-engineered-for-fracture-fixation-and-stabilization
#16
Basel A Khader, Sean A F Peel, Mark R Towler
Glass polyalkenoate cements (GPCs) have potential as bio-adhesives due to their ease of application, appropriate mechanical properties, radiopacity and chemical adhesion to bone. Aluminium (Al)-free GPCs have been discussed in the literature, but have proven difficult to balance injectability with mechanical integrity. For example, zinc-based, Al-free GPCs reported compressive strengths of 63 MPa, but set in under 2 min. Here, the authors design injectable GPCs (IGPCs) based on zinc-containing, Al-free silicate compositions containing GeO₂, substituted for ZnO at 3% increments through the series...
July 5, 2017: Journal of Functional Biomaterials
https://www.readbyqxmd.com/read/28672271/the-fabrication-and-characterization-of-barium-titanate-akermanite-nano-bio-ceramic-with-a-suitable-piezoelectric-coefficient-for-bone-defect-recovery
#17
H Shokrollahi, F Salimi, A Doostmohammadi
In recent years, due to the controllable mechanical properties and degradation rate, calcium silicates such as akermanite (Ca2MgSi2O7) with Ca-Mg and Si- containing bio-ceramics have received much more attention. In addition, the piezoelectric effect plays an important role in bone growth, remodeling and defect healing. To achieve our objective, the porous bioactive nano-composite with a suitable piezoelectric coefficient was fabricated by the freeze-casting technique from the barium titanate and nano-akermanite (BT/nAK) suspension...
October 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28524375/bioprinted-osteogenic-and-vasculogenic-patterns-for-engineering-3d-bone-tissue
#18
Batzaya Byambaa, Nasim Annabi, Kan Yue, Grissel Trujillo-de Santiago, Mario Moisés Alvarez, Weitao Jia, Mehdi Kazemzadeh-Narbat, Su Ryon Shin, Ali Tamayol, Ali Khademhosseini
Fabricating 3D large-scale bone tissue constructs with functional vasculature has been a particular challenge in engineering tissues suitable for repairing large bone defects. To address this challenge, an extrusion-based direct-writing bioprinting strategy is utilized to fabricate microstructured bone-like tissue constructs containing a perfusable vascular lumen. The bioprinted constructs are used as biomimetic in vitro matrices to co-culture human umbilical vein endothelial cells and bone marrow derived human mesenchymal stem cells in a naturally derived hydrogel...
August 2017: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/28516996/growth-of-two-dimensional-silica-and-aluminosilicate-bilayers-on-pd-111-from-incommensurate-to-commensurate-crystalline
#19
Jin-Hao Jhang, Chao Zhou, Omur E Dagdeviren, Gregory S Hutchings, Udo D Schwarz, Eric I Altman
Two-dimensional (2D) silica (SiO2) and aluminosilicate (AlSi3O8) bilayers grown on Pd(111) were fabricated and systematically studied using ultrahigh vacuum surface analysis in combination with theoretical methods, including Auger electron spectroscopy, X-ray photoelectron spectroscopy, low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and density functional theory. Based on LEED results, both SiO2 and AlSi3O8 bilayers start ordering above 850 K in 2 × 10(-6) Torr oxygen. Both bilayers show hexagonal LEED patterns with a periodicity approximately twice that of the Pd(111) surface...
May 31, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28504165/calcium-silicate-nanowires-an-effective-alternative-for-improving-mechanical-properties-of-chitosan-hydroxyethyl-methacrylate-hema-copolymer-nanocomposites
#20
Sarang S Bari, Satyendra Mishra
Nanowires of calcium silicate were successfully synthesized by ultrasonic irradiation process and incorporated into chitosan and hydroxyetheyl methacrylate (HEMA) copolymer matrix by solution blending for efficacious preparation of biodegradable nanocomposites. Remarkable improvement in mechanical properties of the nanocomposites was noticed after micro-tensile analysis. Enlarged surface area and higher aspect ratio of CaSiO3 nanowires were the key factors responsible for such improvement. This was supported by EDS and XRD analysis in terms of proper distribution of nanofiller through the copolymer matrix and corresponding rise in percentage crystallanity respectively...
August 1, 2017: Carbohydrate Polymers
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