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Papers by bijan eftekhari yekta

Research paper thumbnail of Sintering behavior and mechanical properties of zirconia compacts fabricated by uniaxial press forming

The effect of fiber content and sintering temperature on sintering behavior and mechanical proper... more The effect of fiber content and sintering temperature on sintering behavior and mechanical properties of mullite fibers/hydroxyapatite composites was studied. The composites were fabricated by hydrothermal synthesis and pressureless sintering. The amount of fibers was varied from 5 wt % to 15 wt % through hydrothermal synthesis, mullite fibers and hydroxyapatite composite powders were subsequently sintered at temperatures of 1150, 1250, and 1350 • C. The composites presented a more perturbed structure by increasing fiber content. Moreover, the composites experienced pore coalescence and exhibited a dense microstructure at elevated temperature. X-ray diffraction indicated that the composites underwent various chemical reactions and generated silicate glasses. The generation of silicate glasses increased the driving force of particle rearrangement and decreased the number of pores, which promoted densification of the composites. Densification typically leads to increased hardness and bending strength. The study proposes a densification mechanism and opens new insights into the sintering properties of these materials.

Research paper thumbnail of Preparation of monolithic transparent mullite-based glass-ceramics by the sol–gel method

Journal of Non-Crystalline Solids

Research paper thumbnail of Preparation and Characterization of Sn-Containing Glasses for Brachytherapy Applications

Transactions of the Indian Ceramic Society

Research paper thumbnail of Synthesis and characterization of biodegradable AZ31/calcium phosphate glass composites for orthopedic applications

Advanced Composites and Hybrid Materials

Research paper thumbnail of Enhancing Mechanical Properties and Biological Performances of Injectable Bioactive Glass by Gelatin and Chitosan for Bone Small Defect Repair

Bioactive glass (BG) represents a promising biomaterial for bone healing; here injectable BG past... more Bioactive glass (BG) represents a promising biomaterial for bone healing; here injectable BG pastes biological properties were improved by 25 wt% gelatin or chitosan, as well as mechanical resistance was enhanced by adding 10 or 20 wt% 3-Glycidyloxypropyl trimethoxysilane (GPTMS) cross-linker. Composites exhibited bioactivity as apatite formation was observed by SEM and XRD after 14 days immersion in SBF; moreover, polymers did not enhance degradability as weight loss was >10% after 30 days in physiological conditions. BG-gelatin-20 wt% GPTMS composites demonstrated the highest compressive strength (4.8±0.5 MPa) in comparison with 100% BG control (1.9±0.1 MPa). Cytocompatibility was demonstrated towards human mesenchymal stem cells (hMSC), osteoblasts progenitors and endothelial cells. The presence of 20 wt% GPTMS conferred antibacterial properties thus inhibiting the joint pathogens Staphylococcus aureus and Staphylococcus epidermidis infection. Finally, hMSC osteogenesis was su...

Research paper thumbnail of The effect of magnesium on bioactivity, rheology and biology behaviors of injectable bioactive glass-gelatin-3-glycidyloxypropyl trimethoxysilane nanocomposite-paste for small bone defects repair

Research paper thumbnail of Prediction of foaming temperature of glass in the presence of various oxidizers via thermodynamics route

Research paper thumbnail of Rheology, injectability, and bioactivity of bioactive glass containing chitosan/gelatin, nano pastes

Journal of Applied Polymer Science

Research paper thumbnail of Semi-Conducting Glazes Based on Cassiterite Crystalline Phase for Porcelain Insulators Applications: Phase Evolution, Microstructure and Electrical Properties

Transactions of the Indian Ceramic Society

Research paper thumbnail of Crystallization and Optical Properties of Alumino-silicate and Alumino-borosilicate glasses containing Indium Tin oxide

Journal of the European Ceramic Society

Research paper thumbnail of Effect of addition of titanium on structural, mechanical and biological properties of 45S5 glass-ceramic

Research paper thumbnail of The Effects of Vanadium Pentoxide to Oxalic Acid Ratio and Different Atmospheres on the Formation of VO2 Nanopowders Synthesized via Sol–Gel Method

Journal of Electronic Materials

Research paper thumbnail of Thermal and Crystallization Behaviour of SiO2 -PbF2 Glass System in the Presence of ErF3 and Al2 O3

Journal of the American Ceramic Society

Research paper thumbnail of Preparation and characterization of mesoporous electrospun (SiO2)0.59(CaO)0.36−x(P2O5)0.05(TiO2)x glasses (x = 0 and 0.05 mol%)

Journal of Porous Materials, 2016

Research paper thumbnail of Preparation and in-vitro characterization of electrospun bioactive glass nanotubes as mesoporous carriers for ibuprofen

Ceramics International, 2016

Research paper thumbnail of Effect of Partial Substitution of K2O for Na2O on Sintering, Crystallization and Mechanical Properties of SiO2-CaO-K2O-Na2O-CaF2Glass-Ceramics

Transactions of the Indian Ceramic Society, 2016

Research paper thumbnail of Sintering and Crystallization Behavior of Machinable Fluorphlogopite-Gehlenite Glass-Ceramic

Int J Appl Ceram Technol, 2009

ABSTRACT

Research paper thumbnail of Effects of TiO2 and P2O5 on solarization and crystallization of photosensitive lithium silicate glass

Journal of Non-Crystalline Solids, 2015

Research paper thumbnail of Bioactivity and cell proliferation in radiopaque gel-derived CaO–P2O5–SiO2–ZrO2 glass and glass–ceramic powders

Materials Science and Engineering: C, 2015

In this study, 10mol% ZrO2 was added to a 27CaO-5P2O5-68SiO2 (mol%) base composition synthesized ... more In this study, 10mol% ZrO2 was added to a 27CaO-5P2O5-68SiO2 (mol%) base composition synthesized via a simple sol-gel method. This composition is similar to that of a frequently investigated bioactive gel-glass. The effects of ZrO2 on the in vitro bioactivity and MG-63 cell proliferation of the glass and its derivative polycrystalline (glass-ceramic) powder were investigated. The samples were characterized using thermo-gravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) coupled to energy dispersive X-ray spectroscopy (EDS). Release of Si, Ca, P and Zr into simulated body fluid (SBF) was determined by inductively coupled plasma (ICP). Upon heat treatment at 1000°C, the glass powder crystallized into an apatite-wollastonite-zirconia glass-ceramic powder. Hydroxycarbonate apatite (HCA) formation on the surface of the glass and glass-ceramic particles containing ZrO2 was confirmed by FTIR and SEM. Addition of ZrO2 to the base glass composition decreased the rate of HCA formation in vitro from one day to three days, and hence, ZrO2 could be employed to control the rate of apatite formation. However, the rate of HCA formation on the glass-ceramic powder containing ZrO2 crystal was equal to that in the base glassy powder. Tests with a cultured human osteoblast-like MG-63 cells revealed that the glass and glass-ceramic materials stimulated cell proliferation, indicating that they are biocompatible and are not cytotoxic in vitro. Moreover, zirconia clearly increased osteoblast proliferation over that of the Zr-free samples. This increase is likely associated with the lower solubility of these samples and, consequently, a smaller variation in the media pH. Despite the low solubility of these materials, bioactivity was maintained, indicating that these glassy and polycrystalline powders are potential candidates for bone graft substitutes and bone cements with the special feature of radiopacity.

Research paper thumbnail of Sol-gel synthesis, structure, sintering and properties of bioactive and inert nano apatite-zirconia glass-ceramics

Ceramics International, 2015

ABSTRACT gel synthesis, structure, sintering and properties of bioactive and inert nano apatite-z... more ABSTRACT gel synthesis, structure, sintering and properties of bioactive and inert nano apatite-zirconia glass-ceramics, Ceramics International, http://dx.

Research paper thumbnail of Sintering behavior and mechanical properties of zirconia compacts fabricated by uniaxial press forming

The effect of fiber content and sintering temperature on sintering behavior and mechanical proper... more The effect of fiber content and sintering temperature on sintering behavior and mechanical properties of mullite fibers/hydroxyapatite composites was studied. The composites were fabricated by hydrothermal synthesis and pressureless sintering. The amount of fibers was varied from 5 wt % to 15 wt % through hydrothermal synthesis, mullite fibers and hydroxyapatite composite powders were subsequently sintered at temperatures of 1150, 1250, and 1350 • C. The composites presented a more perturbed structure by increasing fiber content. Moreover, the composites experienced pore coalescence and exhibited a dense microstructure at elevated temperature. X-ray diffraction indicated that the composites underwent various chemical reactions and generated silicate glasses. The generation of silicate glasses increased the driving force of particle rearrangement and decreased the number of pores, which promoted densification of the composites. Densification typically leads to increased hardness and bending strength. The study proposes a densification mechanism and opens new insights into the sintering properties of these materials.

Research paper thumbnail of Preparation of monolithic transparent mullite-based glass-ceramics by the sol–gel method

Journal of Non-Crystalline Solids

Research paper thumbnail of Preparation and Characterization of Sn-Containing Glasses for Brachytherapy Applications

Transactions of the Indian Ceramic Society

Research paper thumbnail of Synthesis and characterization of biodegradable AZ31/calcium phosphate glass composites for orthopedic applications

Advanced Composites and Hybrid Materials

Research paper thumbnail of Enhancing Mechanical Properties and Biological Performances of Injectable Bioactive Glass by Gelatin and Chitosan for Bone Small Defect Repair

Bioactive glass (BG) represents a promising biomaterial for bone healing; here injectable BG past... more Bioactive glass (BG) represents a promising biomaterial for bone healing; here injectable BG pastes biological properties were improved by 25 wt% gelatin or chitosan, as well as mechanical resistance was enhanced by adding 10 or 20 wt% 3-Glycidyloxypropyl trimethoxysilane (GPTMS) cross-linker. Composites exhibited bioactivity as apatite formation was observed by SEM and XRD after 14 days immersion in SBF; moreover, polymers did not enhance degradability as weight loss was >10% after 30 days in physiological conditions. BG-gelatin-20 wt% GPTMS composites demonstrated the highest compressive strength (4.8±0.5 MPa) in comparison with 100% BG control (1.9±0.1 MPa). Cytocompatibility was demonstrated towards human mesenchymal stem cells (hMSC), osteoblasts progenitors and endothelial cells. The presence of 20 wt% GPTMS conferred antibacterial properties thus inhibiting the joint pathogens Staphylococcus aureus and Staphylococcus epidermidis infection. Finally, hMSC osteogenesis was su...

Research paper thumbnail of The effect of magnesium on bioactivity, rheology and biology behaviors of injectable bioactive glass-gelatin-3-glycidyloxypropyl trimethoxysilane nanocomposite-paste for small bone defects repair

Research paper thumbnail of Prediction of foaming temperature of glass in the presence of various oxidizers via thermodynamics route

Research paper thumbnail of Rheology, injectability, and bioactivity of bioactive glass containing chitosan/gelatin, nano pastes

Journal of Applied Polymer Science

Research paper thumbnail of Semi-Conducting Glazes Based on Cassiterite Crystalline Phase for Porcelain Insulators Applications: Phase Evolution, Microstructure and Electrical Properties

Transactions of the Indian Ceramic Society

Research paper thumbnail of Crystallization and Optical Properties of Alumino-silicate and Alumino-borosilicate glasses containing Indium Tin oxide

Journal of the European Ceramic Society

Research paper thumbnail of Effect of addition of titanium on structural, mechanical and biological properties of 45S5 glass-ceramic

Research paper thumbnail of The Effects of Vanadium Pentoxide to Oxalic Acid Ratio and Different Atmospheres on the Formation of VO2 Nanopowders Synthesized via Sol–Gel Method

Journal of Electronic Materials

Research paper thumbnail of Thermal and Crystallization Behaviour of SiO2 -PbF2 Glass System in the Presence of ErF3 and Al2 O3

Journal of the American Ceramic Society

Research paper thumbnail of Preparation and characterization of mesoporous electrospun (SiO2)0.59(CaO)0.36−x(P2O5)0.05(TiO2)x glasses (x = 0 and 0.05 mol%)

Journal of Porous Materials, 2016

Research paper thumbnail of Preparation and in-vitro characterization of electrospun bioactive glass nanotubes as mesoporous carriers for ibuprofen

Ceramics International, 2016

Research paper thumbnail of Effect of Partial Substitution of K2O for Na2O on Sintering, Crystallization and Mechanical Properties of SiO2-CaO-K2O-Na2O-CaF2Glass-Ceramics

Transactions of the Indian Ceramic Society, 2016

Research paper thumbnail of Sintering and Crystallization Behavior of Machinable Fluorphlogopite-Gehlenite Glass-Ceramic

Int J Appl Ceram Technol, 2009

ABSTRACT

Research paper thumbnail of Effects of TiO2 and P2O5 on solarization and crystallization of photosensitive lithium silicate glass

Journal of Non-Crystalline Solids, 2015

Research paper thumbnail of Bioactivity and cell proliferation in radiopaque gel-derived CaO–P2O5–SiO2–ZrO2 glass and glass–ceramic powders

Materials Science and Engineering: C, 2015

In this study, 10mol% ZrO2 was added to a 27CaO-5P2O5-68SiO2 (mol%) base composition synthesized ... more In this study, 10mol% ZrO2 was added to a 27CaO-5P2O5-68SiO2 (mol%) base composition synthesized via a simple sol-gel method. This composition is similar to that of a frequently investigated bioactive gel-glass. The effects of ZrO2 on the in vitro bioactivity and MG-63 cell proliferation of the glass and its derivative polycrystalline (glass-ceramic) powder were investigated. The samples were characterized using thermo-gravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) coupled to energy dispersive X-ray spectroscopy (EDS). Release of Si, Ca, P and Zr into simulated body fluid (SBF) was determined by inductively coupled plasma (ICP). Upon heat treatment at 1000°C, the glass powder crystallized into an apatite-wollastonite-zirconia glass-ceramic powder. Hydroxycarbonate apatite (HCA) formation on the surface of the glass and glass-ceramic particles containing ZrO2 was confirmed by FTIR and SEM. Addition of ZrO2 to the base glass composition decreased the rate of HCA formation in vitro from one day to three days, and hence, ZrO2 could be employed to control the rate of apatite formation. However, the rate of HCA formation on the glass-ceramic powder containing ZrO2 crystal was equal to that in the base glassy powder. Tests with a cultured human osteoblast-like MG-63 cells revealed that the glass and glass-ceramic materials stimulated cell proliferation, indicating that they are biocompatible and are not cytotoxic in vitro. Moreover, zirconia clearly increased osteoblast proliferation over that of the Zr-free samples. This increase is likely associated with the lower solubility of these samples and, consequently, a smaller variation in the media pH. Despite the low solubility of these materials, bioactivity was maintained, indicating that these glassy and polycrystalline powders are potential candidates for bone graft substitutes and bone cements with the special feature of radiopacity.

Research paper thumbnail of Sol-gel synthesis, structure, sintering and properties of bioactive and inert nano apatite-zirconia glass-ceramics

Ceramics International, 2015

ABSTRACT gel synthesis, structure, sintering and properties of bioactive and inert nano apatite-z... more ABSTRACT gel synthesis, structure, sintering and properties of bioactive and inert nano apatite-zirconia glass-ceramics, Ceramics International, http://dx.