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https://www.readbyqxmd.com/read/28439577/shear-bond-strength-of-lining-materials-to-calciumsilicate-cements-at-different-time-intervals
#1
Alena Schmidt, Edgar Schäfer, Till Dammaschke
PURPOSE: To compare the shear bond strength of three different light-curing, flowable composites (Ionoseal [IS], Vertise flow [VF], and Futurabond NR + Grandio Flow [GF]) on MTA-Angelus [MTA] or Biodentine [BD] at three different time intervals. MATERIALS AND METHODS: Freshly mixed MTA or BD was applied into 180 identical plaster molds. Three minutes, 15 min, and 2 days after mixing, specimens of IS, VF, and GF with standardized size and diameter were applied on MTA and BD specimens (n = 10 per material and time interval)...
April 21, 2017: Journal of Adhesive Dentistry
https://www.readbyqxmd.com/read/28435372/histologic-evaluation-of-the-effect-of-mineral-trioxide-aggregate-fillapex-as-a-root-canal-sealer-in-rat-teeth-submitted-to-late-replantation
#2
Manuel Marques Ferreira, Maria Filomena Botelho, Margarida Abrantes, Lina Carvalho, Eunice Carrilho
OBJECTIVE: This study aims to analyze the effect of new root canal based silicate cement, in rat teeth after late replantation, comparing with calcium hydroxide (CH) in preventing tooth root resorption. MATERIALS AND METHODS: The study group included 16 Wistar rats in which the upper right central incisors were extracted and were left on a worktable for 60 min, simulating a case of tooth avulsion, after had been anesthetized. One group, (Group I), the canals were filled with CH past, before replantation...
January 2017: European Journal of Dentistry
https://www.readbyqxmd.com/read/28433242/freeform-extrusion-fabrication-of-titanium-fiber-reinforced-13-93-bioactive-glass-scaffolds
#3
Albin Thomas, Krishna C R Kolan, Ming C Leu, Gregory E Hilmas
Although implants made with bioactive glass have shown promising results for bone repair, their application in repairing load-bearing long bone is limited due to their poor mechanical properties in comparison to human bone. This work investigates the freeform extrusion fabrication of bioactive silicate 13-93 glass scaffolds reinforced with titanium (Ti) fibers. A composite paste prepared with 13-93 glass and Ti fibers (~16µm in diameter and lengths varying from ~200µm to ~2 mm) was extruded through a nozzle to fabricate scaffolds (0-90° filament orientation pattern) on a heated plate...
June 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28433153/polyethylenimine-kappa-carrageenan-micro-arc-oxidation-coating-for-passivation-of-magnesium-alloy
#4
A Golshirazi, M Kharaziha, M A Golozar
The aim of this study was to combine micro-arc oxidation (MAO) and self-assembly technique to improve corrosion resistivity of AZ91 alloy. While a silicate-fluoride electrolyte was adopted for MAO treatment, polyethylenimine (PEI)/kappa carrageenan (KC) self-assembly coating was applied as the second coating layer. Resulted demonstrated the formation of forsterite-fluoride containing MAO coating on AZ91 alloy depending on the voltage and time of anodizing process. Addition of the second PEI/KC coating layer on MAO treated sample effectively enhanced the adhesive strength of MAO coated sample due to filling the pores with polymers and increase in the mechanical interlocking of coating to the substrate...
July 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28430466/evidence-for-anomalous-dynamic-heterogeneities-in-isostatic-supercooled-liquids
#5
M Micoulaut, M Bauchy
Upon cooling, the dynamics of supercooled liquids exhibits a growing transient spatial distribution of relaxation times that is known as dynamic heterogeneities. The relationship between this now well-established crucial feature of the glass transition and some underlying liquid properties remains challenging and elusive in many respects. Here we report on computer simulations of liquids with a changing network structure (densified silicates), and show that there is a deep and important link between the mechanical nature characterized by topological constraints and the spatial extent of such fluctuations...
April 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28427568/inter-and-intra-specific-growth-and-domoic-acid-production-in-relation-to-nutrient-ratios-and-concentrations-in-pseudo-nitzschia-phosphate-an-important-factor
#6
Kimberley A Lema, Marie Latimier, Élisabeth Nézan, Juliette Fauchot, Mickael Le Gac
The factors responsible for inducing the synthesis of toxins and responses from toxic phytoplankton blooms remain unclear. In this study we compare the influence of genotypic (at both the intra and interspecific levels) and environmental factors (nutrient concentration and ratio) on growth (in terms of cell densities) and domoic acid (DA) production in three Pseudo-nitzschia species: P. australis, P.pungens and P.fradulenta. A strong phosphate effect was detected. More precisely, a low initial concentration in phosphate, even at high initial nitrogen and silicate concentrations, induced the highest DA concentrations and the lowest cell densities in all strains/species studied...
April 2017: Harmful Algae
https://www.readbyqxmd.com/read/28421442/silica-containing-inclusions-in-the-cytoplasm-of-diatom-synedra-acus
#7
M A Grachev, Ye D Bedoshvili, E Yu Gerasimov, V I Zaikovskii, K V Gneusheva, Ye V Likhoshway
Cells of the araphid pennate diatom Synedra acus subsp. radians contain large inclusion (1-15 μm) storing silica, as revealed by transmission electron microscopy and EDX-analysis. The size of the inclusions increases with the time of cultivation of diatoms. Approximate concentration of SiO2 in the inclusions is 1-4%. It is assumed that silica in the inclusions is present as gelatinized silica-gel. These results explain the possible mechanism of transport of silicic acid into the cell against the concentration gradient...
January 2017: Doklady. Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28418704/false-negatives-for-remote-life-detection-on-ocean-bearing-planets-lessons-from-the-early-earth
#8
Christopher T Reinhard, Stephanie L Olson, Edward W Schwieterman, Timothy W Lyons
Ocean-atmosphere chemistry on Earth has undergone dramatic evolutionary changes throughout its long history, with potentially significant ramifications for the emergence and long-term stability of atmospheric biosignatures. Though a great deal of work has centered on refining our understanding of false positives for remote life detection, much less attention has been paid to the possibility of false negatives, that is, cryptic biospheres that are widespread and active on a planet's surface but are ultimately undetectable or difficult to detect in the composition of a planet's atmosphere...
April 2017: Astrobiology
https://www.readbyqxmd.com/read/28415541/synthesis-characterization-of-caf2-doped-silicate-glass-ceramics
#9
Madeeha Riaz, Rehana Zia, Ambreen Mirza, Tousif Hussain, Farooq Bashir, Safia Anjum
This paper reports the fabrication and characterization of silicate glass-ceramics doped with (0-12mol%) CaF2. TGA-DSC analysis was carried out to determine the crystallization temperature and stability of glass measured by two glass parameters; Hruby parameter KH=(Tx-Tg)/(TL-Tx) and Weinberg parameter KW=(Tc-Tg)/TL. It was found that with CaF2 doping improved sinterability at low temperature and provided stability to the glass. The XRD pattern exhibits a single phase of combeite and doping of CaF2 cause increase in crystallite size...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28415532/preparation-of-micro-porous-bioceramic-containing-silicon-substituted-hydroxyapatite-and-beta-tricalcium-phosphate
#10
Lih-Jyh Fuh, Ya-Jing Huang, Wen-Cheng Chen, Dan-Jae Lin
Dimensional instability caused by sintering shrinkage is an inevitable drawback for conventional processing of hydroxyapatite (HA). A new preparation method for biphasic calcium phosphates was developed to increase micro pores and biodegradation without significant dimensional change. Powder pressed HA discs, under 100MPa, were immersed in a colloidal mixture of tetraethoxysilane (TEOS) and ammonium hydroxide for 10min, followed by drying, and then were sintered at 900°C, 1050°C, and 1200°C, respectively...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28415507/influences-of-doping-mesoporous-magnesium-silicate-on-water-absorption-drug-release-degradability-apatite-mineralization-and-primary-cells-responses-to-calcium-sulfate-based-bone-cements
#11
Zhengrong Gu, Sicheng Wang, Weizong Weng, Xiao Chen, Liehu Cao, Jie Wei, Jung-Woog Shin, Jiacan Su
In this study, composite cements containing mesoporous magnesium silicate (m-MS) and calcium sulfate (CS) were fabricated. The results revealed that the setting time of the m-MS/CS composite cements (m-MSC) slightly prolonged with the increase of m-MS content while the compressive strength suffered a little loss. The doping of m-MS improved the water absorption, drug release (vancomycin) and degradability of the m-MSC in Tris-HCl solution (pH=7.4). In addition, addition of m-MS facilitated the apatite-mineralization of m-MSC in simulated body fluid (SBF), indicating good bioactivity...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28415499/antibacterial-effect-of-peo-coating-with-silver-on-aa7075
#12
P Cerchier, L Pezzato, K Brunelli, P Dolcet, A Bartolozzi, R Bertani, M Dabalà
In this work, plasma electrolytic oxidation (PEO) coatings were produced on AA7075 using alkaline solution containing silicates compounds and silver micrometric particles in order to give to the coating an antimicrobial effect. In the optic of circular economy, silver chloride derived from the acid pre-treatment of electronic scraps was used as raw material and successively silver powders were synthesized from silver chloride solution using glucose syrup as reducing agent. The coatings were characterized by scanning electron microscope (SEM), X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization test and antimicrobial tests...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28415463/in-vitro-characterisation-of-a-sol-gel-derived-in-situ-silica-coated-silicate-and-carbonate-co-doped-hydroxyapatite-nanopowder-for-bone-grafting
#13
Seyed Mohsen Latifi, Mohammadhossein Fathi, Ali Sharifnabi, Jaleh Varshosaz
Design and synthesis of materials with better properties and performance are essential requirements in the field of biomaterials science that would directly improve patient quality of life. For this purpose, in situ silica-coated silicate and carbonate co-doped hydroxyapatite (Sc/S.C.HA) nanopowder was synthesized via the sol-gel method. Characterisation of the prepared nanopowder was carried out by XRD, FTIR, TEM, SEM, EDX, ICP, zeta potential, acid dissolution test, and cell culture test. The substitution of the silicate and carbonate ions into hydroxyapatite structure was confirmed by FTIR analysis...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28413692/photoredox-mediated-routes-to-radicals-the-value-of-catalytic-radical-generation-in-synthetic-methods-development
#14
REVIEW
Jennifer K Matsui, Simon B Lang, Drew R Heitz, Gary A Molander
Photoredox catalysis has experienced a revitalized interest from the synthesis community during the past decade. For example, photoredox/Ni dual catalysis protocols have been developed to overcome several inherent limitations of palladium-catalyzed cross-couplings by invoking a single-electron transmetalation pathway. This Perspective highlights advances made by our laboratory since the inception of the photoredox/Ni cross-coupling of benzyltrifluoroborates with aryl bromides. In addition to broadening the scope of trifluoroborate coupling partners, research using readily oxidized hypervalent silicates as radical precursors that demonstrate functional group compatibility is highlighted...
April 7, 2017: ACS Catalysis
https://www.readbyqxmd.com/read/28411516/effects-of-foliar-dressing-of-selenite-and-silicate-alone-or-combined-with-different-soil-ameliorants-on-the-accumulation-of-as-and-cd-and-antioxidant-system-in-brassica-campestris
#15
Yongzhen Ding, Yongjiu Wang, Xiangqun Zheng, Weimin Cheng, Rongguang Shi, Renwei Feng
This study was conducted to investigate the possibility of using a combined technology to synchronously reduce As and Cd accumulation in the edible parts of Brassica campestris. The results showed that a foliar application of selenite (Se) and silicon (Si) combined with soil ameliorants (including Ca-Mg-P fertilizer, sodium silicate and red mud) showed limited effects on the growth of B. campestris. The As concentration in the leaves of B. campestris in all treatments was below the Chinese safety standard. When sodium silicate and Ca-Mg-P fertilizer were added to the soil, the additional foliar application of Se and Si could in some cases help further reduce the concentrations of As and Cd in the leaves of B...
April 12, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28406027/gelatin-derived-graphene-silicate-hybrid-materials-are-biocompatible-and-synergistically-promote-bmp9-induced-osteogenic-differentiation-of-mesenchymal-stem-cells-mscs
#16
Yulong Zou, Nader Taheri Qazvini, Kylie Zane, Monirosadat Sanaz Sadati, Qiang Wei, Junyi Liao, Jiaming Fan, Dongzhe Song, Jianxiang Liu, Chao Ma, Xiangyang Qu, Liqun Chen, Xinyi Yu, Zhicai Zhang, Chen Zhao, Zongyue Zeng, Ruyi Zhang, Shujuan Yan, Tingting Wu, Xingye Wu, Yi Shu, Yasha Li, Wenwen Zhang, Russell R Reid, Michael J Lee, Jennifer M Wolf, Matthew Tirrell, Tong-Chuan He, Juan J de Pablo, Zhong-Liang Deng
Graphene-based materials have been used in many fields but have only found limited applications in biomedicine, including bone tissue engineering. Here we demonstrate that novel hybrid materials consisting of gelatin-derived graphene and silicate nanosheets of Laponite (GL) are biocompatible and promote osteogenic differentiation of mesenchymal stem cells (MSCs). Homogeneous cell attachment, long-term proliferation and osteogenic differentiation of MSCs on GL-scaffold were confirmed by optical microscopy, and scanning electron microscopy...
April 13, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28405005/carbon-bearing-silicate-melt-at-deep-mantle-conditions
#17
Dipta B Ghosh, Suraj K Bajgain, Mainak Mookherjee, Bijaya B Karki
Knowledge about the incorporation and role of carbon in silicate magmas is crucial for our understanding of the deep mantle processes. CO2 bearing silicate melting and its relevance in the upper mantle regime have been extensively explored. Here we report first-principles molecular dynamics simulations of MgSiO3 melt containing carbon in three distinct oxidation states - CO2, CO, and C at conditions relevant for the whole mantle. Our results show that at low pressures up to 15 GPa, the carbon dioxide speciation is dominated by molecular form and carbonate ions...
April 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28403611/kot-bu-catalyzed-dehydrogenative-c-h-silylation-of-heteroaromatics-a-combined-experimental-and-computational-mechanistic-study
#18
Wen-Bo Liu, David P Schuman, Yun-Fang Yang, Anton Alexandrovich Toutov, Yong Liang, Hendrik F T Klare, Nasri Nesnas, Martin Oestreich, Donna G Blackmond, Scott C Virgil, Shibdas Banerjee, Richard N Zare, Robert H Grubbs, Kendall N Houk, Brian M Stoltz
We recently reported a new method for the direct dehydrogenative C-H silylation of heteroaromatics utilizing Earth-abundant potassium tert-butoxide. Herein we report a systematic experimental and computational mechanistic investigation of this transformation. Our experimental results are consistent with a radical chain mechanism. A trialkylsilyl radical may be initially generated by homolytic cleavage of a weakened Si-H bond of a hypercoordinated silicon species as detected by IR, or by traces of oxygen which can generate a reactive peroxide by reaction with (KOt-Bu)4 as indicated by density functional theory (DFT) calculations...
April 12, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28402086/the-effect-of-increased-microporosity-on-bone-formation-within-silicate-substituted-scaffolds-in-an-ovine-posterolateral-spinal-fusion-model
#19
Melanie Jean Coathup, Gordon William Blunn, Charlie Campion, Chih-Yuan Ho, Karin Angela Hing
This study compared the bone forming capacity of the same formulation of silicate-substituted bone graft substitute materials with different microporosity in an instrumented posterolateral spinal fusion ovine model. Materials with a strut porosity of (i) 22.5% (SiCaP) or (ii) 36.0% (SiCaP(+)) were packed along either side of the spine. Bone apposition rates, % new bone formation, % bone-implant contact, and % graft resorption were quantified at 8, 12, and 24 weeks post surgery. Computed Tomography (CT) was used to grade the formation of fusion bridges between vertebrae...
May 2017: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
https://www.readbyqxmd.com/read/28400787/silicification-in-grasses-variation-between-different-cell-types
#20
REVIEW
Santosh Kumar, Milan Soukup, Rivka Elbaum
Plants take up silicon as mono-silicic acid, which is released to soil by the weathering of silicate minerals. Silicic acid can be taken up by plant roots passively or actively, and later it is deposited in its polymerized form as amorphous hydrated silica. Major silica depositions in grasses occur in root endodermis, leaf epidermal cells, and outer epidermal cells of inflorescence bracts. Debates are rife about the mechanism of silica deposition, and two contrasting scenarios are often proposed to explain it...
2017: Frontiers in Plant Science
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