Graphene-containing PCL- coated Porous 13-93B3 Bioactive Glass Scaffolds for Bone Regeneration

Borate-based 13-93B3 bioactive glass scaffolds were coated with the graphene-containing poly-caprolactone (PCL) solution to prepare electrically conductive composites for biomedical applications. Results revealed that electrical conductivity of the scaffolds increased with increasing concentration of graphene nanoparticles. Significant difference was not observed in hydroxyapatite forming ability of the bare and the graphene-containing scaffolds immersed in simulated body fluid. In vitro cytotoxicity experiments (XTT tests) showed that pre-osteoblastic MC3T3-E1 cell viability percentages of the graphene- containing samples was higher than control group samples after 7 days of incubation. However, a decrease in cell viability rates was obtained after 14 days of incubation for samples coated with PCL containing graphene starting from 3 wt%. Additionally, results obtained in the live-dead assay were consistent with the results of XTT tests. A higher ALP activity was detected in cells cultured on the graphene-containing borate glass scaffolds than those on the bare PCL coated 13-93B3 scaffolds suggesting the presence of graphene nanopowders stimulated an early stage of osteoblastic differentiation. SEM analysis showed that MC3T3-E1 cells exhibited a flat appearance and spread out through the surface in all groups of scaffolds starting from 3 days of incubation. © 2018 IOP Publishing Ltd

Towards better understanding of structural, physical and radiation attenuation properties of the granites in Aegean region of Turkey: Izmir and Kutahya Provinces

In this study, physical, chemical, structural and radiation attenuation properties of some granite samples collected from Kutahya-Simav and Izmir (Bergama and Karaburun) were investigated. The true particle density of the studied granite samples was in the range of 2.65 g cm(-3) to 2.72 g cm(-3) and the median particle diameter was between similar to 12 mu m and 41 mu m. According to the structural examination results obtained from the study, the chemical compositions of the extracted granite samples varied by area. While SiO2 was the dominating component in certain locations, it was replaced by Fe2O3 in another. This condition also had a direct effect on the densities of the granite samples extracted. At the conclusion of the study, it was found that the predominant factor affecting the radiation shielding characteristics of granites was the quantity of Fe2O3 in the composition, with the greatest gamma-ray shielding qualities supplied by samples 4 and 5, which had the highest Fe2O3 ratio. Our results indicate that sample 5 and the previously studied Capao Bonita sample had comparable half value layer values at low, medium, and high gamma ray levels. It may be concluded that Izmir granites are a more attractive option to granite for usage as radiation shielding building materials, owing to their high Fe2O3 concentration, and may be a feasible alternative to less desirable concrete materials for shielding applications

Direct-write Assembly of Silicate and Borate Bioactive Glass Scaffolds For Bone Repair

Silicate (13-93) and borate (13-93B3) bioactive glass scaffolds were created by robotic deposition (robocasting) of organic solvent-based suspensions and evaluated in vitro for potential application in bone repair. Suspensions (inks) were developed, characterized, and deposited layer-by-layer to form three-dimensional scaffolds with a grid-like microstructure (porosity ≈50%; pore width 420 ± 30 μm). The mechanical response of the scaffolds was tested in compression, and the conversion of the glass to hydroxyapatite (HA)-like material in a simulated body fluid (SBF) was evaluated. As fabricated, the 13-93 scaffolds had a compressive strength 142 ± 20 MPa, comparable to the strength of human cortical bone, while the strength of the 13-93B3 scaffolds (65 ± 11 MPa), was far higher than that for trabecular bone. when immersed in SBF, the borate 13-93B3 scaffolds converted faster than the silicate 13-93 scaffolds to an HA-like material, but they also showed a sharper decrease in strength with immersion time. Based on their high compressive strength and bioactivity, the scaffolds fabricated in this work by robocasting could have potential application in the repair of load-bearing bone

Effects of Eu3+, Gd3+ and Yb3+ substitution on the structural, photoluminescence, and decay properties of silicate-based bioactive glass powders

Bioactive glass (BG) powders containing europium (Eu3+), gadolinium (Gd3+) and ytterbium (Yb3+) were synthesized through sol-gel process. Effects of the related rare-earth ions on the structural, photoluminescence (PL), and decay characteristics were investigated. In vitro, acellular bioactivity of the synthesized powders was examined in simulated body fluid (SBF). Results revealed that all of the BG powders tested in the study showed PL emission under excitation at 374 nm. Among the rare earth dopants tested in the study, Eu3+-containing samples exhibited the strongest emission intensities and for all the glasses optimum dopant concentration was 3 wt% based on the luminescence properties. The synthesized BG have ability to convert to hydroxyapatite (HA) after immersion in SBF. However, more detailed studies with resolution techniques are needed to confirm these observations, that the BG containing Eu3+, Gd3+, and Yb3+ have the ability to form HA and can be used in biomedical applications

Evaluation of Borate Bioactive Glass Scaffolds with Different Pore Sizes in a Rat Subcutaneous Implantation Model

Borate bioactive glass has been shown to convert faster and more completely to hydroxyapatite and enhance new bone formation in vivo when compared to silicate bioactive glass (such as 45S5 and 13-93 bioactive glass). In this work, the effects of the borate glass microstructure on its conversion to hydroxyapatite (HA) in vitro and its ability to support tissue ingrowth in a rat subcutaneous implantation model were investigated. Bioactive borate glass scaffolds, designated 13-93B3, with a grid-like microstructure and pore widths of 300, 600, and 900 μm were prepared by a robocasting technique. The scaffolds were implanted subcutaneously for 4 weeks in Sprague Dawley rats. Silicate 13-93 glass scaffolds with the same microstructure were used as the control. The conversion of the scaffolds to HA was studied as a function of immersion time in a simulated body fluid. Histology and scanning electron microscopy were used to evaluate conversion of the bioactive glass implants to hydroxyapatite, as well as tissue ingrowth and blood vessel formation in the implants. The pore size of the scaffolds was found to have little effect on tissue infiltration and angiogenesis after the 4-week implantation

Remote sensing in management of mining land and proximate habitat

Although remote sensing technology has been available for many years, it has rarely been used for monitoring mining activity. Recent studies indicate that remote sensing is also a valuable tool for managing and planning certain aspects of the mining operation. In this paper, we examine areal expansion of marble quarries and the affected vegetation over a period of 10 years in the Mugla region in Turkey, using geographic information system (GIS) and remote sensing (RS) techniques. Images captured by ASTER Level 3A01 (3D Ortho Data Set), Landsat 5, and Landsat 7 satellites between 2001 and 2009 were used for the analysis. Changes in the natural vegetation as a function of the production level in the marble quarry were calculated using the normalized difference vegetation index. According to the study results, land cover and natural vegetation decreased by less than 3 per cent and 1 per cent respectively between 2001 and 2009, following an upsurge in mining activity in the region