Evaluation of the electrical properties of Gd2O3-stabilized ZrO2 at two representative temperatures

Fathollah Moztarzadeh 한양대학교 세라믹연구소 2014 Journal of Ceramic Processing Research Vol.15 No.6

Zirconia doped with ceramic oxides such as CaO, Y2O3 and Gd2O3 is a good structural material and a well-known ionic conductor .In the present study the electrical properties of gadolinium oxide doped zirconia at different temperatures were studied. The results show that the maximum conductivity of Gd2O3 stabilized zirconia can be obtained by adding 10 mol% of Gd2O3, which is necessary to form a fluorite type solid solution. Finally the electrical conductivity mechanism in zirconia which has been stabilized by adding different types of dopants is discussed.

Sol-gel synthesis and apatite-formation ability of nanostructure merwinite (Ca3MgSi2O8) as a novel bioceramic

Fatollah Moztarzadeh 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.6

Formation of hydroxyapatite nanoneedles on the surface of a novel calcium phosphate/blood plasma proteins biocement in simulated body fluid (SBF)

Mahdi Rezvannia,Fathollah Moztarzadeh,Mohammadreza Tahriri 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.5

In this study, we report on needle-like hydroxyapatite grown on the surface of calcium phosphate/blood plasma proteins biocement in simulated body fluid (SBF). Scanning electron microscope revealed the formation of nano-sized needle-like hydroxyapatite crystals on the surface of the biocement after 7 days immersion in the simulated body fluid. X-ray diffraction analysis of the biocement structures indicated that the nanoneedle crystals were hydroxyapatite. Finally Fourier transform infra-red investigations were employed to detect the functional groups of the biocement which this technique demonstrated to be hydroxyapatite. In this study, we report on needle-like hydroxyapatite grown on the surface of calcium phosphate/blood plasma proteins biocement in simulated body fluid (SBF). Scanning electron microscope revealed the formation of nano-sized needle-like hydroxyapatite crystals on the surface of the biocement after 7 days immersion in the simulated body fluid. X-ray diffraction analysis of the biocement structures indicated that the nanoneedle crystals were hydroxyapatite. Finally Fourier transform infra-red investigations were employed to detect the functional groups of the biocement which this technique demonstrated to be hydroxyapatite.

Preparation of hydroxyapatite ceramics for biomedical applications

M. Haghbin Nazarpak,F. Moztarzadeh,M. Solati-Hashjin 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.1

Hydroxyapatite (HA) is the main component of hard tissue and because of its high biocompatibility and bioactivity makes a strong bond with hard tissue. In this research, hydroxyapatite powders were uniaxially compacted at 86 MPa to form cylindrical shaped samples and sintered at 700-1300℃ with one hour soaking time. The density measured was between 2.89 and 3.49 g/cm³. Phase analyses were performed using X- ray diffraction and the results revealed there was no sign of HA decomposition. Three and four point bending strengths were measured between 7 to 44 MPa. Microstructural studies with a scanning electron microscope (SEM) showed that hydroxyapatite ceramics formed a highly integrated structure with an increase in the sintering temperature up to 1300℃. It was proved that the sintered samples of hydroxyapatite did not contain any unwanted phase. These results imply that the blocks prepared in this study have the potential for use as biomedical implants. Hydroxyapatite (HA) is the main component of hard tissue and because of its high biocompatibility and bioactivity makes a strong bond with hard tissue. In this research, hydroxyapatite powders were uniaxially compacted at 86 MPa to form cylindrical shaped samples and sintered at 700-1300℃ with one hour soaking time. The density measured was between 2.89 and 3.49 g/cm³. Phase analyses were performed using X- ray diffraction and the results revealed there was no sign of HA decomposition. Three and four point bending strengths were measured between 7 to 44 MPa. Microstructural studies with a scanning electron microscope (SEM) showed that hydroxyapatite ceramics formed a highly integrated structure with an increase in the sintering temperature up to 1300℃. It was proved that the sintered samples of hydroxyapatite did not contain any unwanted phase. These results imply that the blocks prepared in this study have the potential for use as biomedical implants.

Evaluation of a prepared sol-gel bioactive glass fiber-reinforced calcium phosphate cement

N. Nezafati,F. Moztarzadeh,S. Hesaraki 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.3

In this article 5-25 V% of a sol-gel bioglass fiber was incorporated into calcium phosphate bone cement to improve its mechanical properties. Compressive strength, work of fracture, elastic modulus and setting time of the cement were investigated as well as phase changes occurring during soaking the specimens in simulated body fluid (SBF). The cement microstructure was also observed by scanning electron microscope (SEM). The results showed that the compressive strength of the set cements without any fibers was 0.635 MPa which was optimally increased to 3.69 MPa by using 15% fibers and then decreased by further addition of the glass phase. In addition, both the work-of-fracture and elastic modulus of the cement were considerably increased when using the fibers in the cement composition. Setting time slightly decreased by using the fibers. A considerable content of the reactants in both fiber-free and fiber-containing cements were transformed to the apatite phase during soaking sample in SBF.

Nanostructured Hydroxyapatite for Biomedical Applications: From Powder to Bioceramic

Eslami, Hossein,Tahriri, Mohammadreza,Moztarzadeh, Fathollah,Bader, Rizwan,Tayebi, Lobat The Korean Ceramic Society 2018 한국세라믹학회지 Vol.55 No.6

In this study, a wet chemical method was used to synthesize nanostructured hydroxyapatite for biomedical applications. Diammonium hydrogen phosphate and calcium nitrate 4-hydrate were used as starting materials with a sodium hydroxide solution as an agent for pH adjustment. Scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, differential thermal analysis, thermal gravimetric analysis, atomic absorption spectroscopy, and ethylenediaminetetraacetic acid (EDTA) titration analysis were used to characterize the synthesized powders. Having been uniaxially pressed, the powders formed a disk-like shape. The sinterability and electrical properties of the samples were examined, and the three-point bending test allowed for the measurement of their mechanical properties. Sedimentation analysis was used to analyze the slurry ability of hydroxyapatite. As in-vitro biological properties of the samples, biocompatibility and cytotoxicity were assessed using osteoblast-like cells and the L929 cell line, respectively. Solubility was assessed by employing a simulated body fluid.

Surface Reactivity and in vitro Biological Evaluation of Sol Gel Derived Silver/calcium Silicophosphate Bioactive Glass

Nader Nezafati,Fathollah Moztarzadeh,Saeed Hesaraki 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.4

Ag ions are known for their antibacterial effects. Ag containing silicate glasses have been extended to create bioactive glasses that exhibit inhibitory effects on bacterial growth using different techniques. In this work,calcium and calcium/silver silicophosphate glasses were synthesized from the sol-gel process and their physicochemical and in vitro biological properties were studied and compared. The effect of silver concentration on in vitro bioactivity and antibacterial properties of the glasses was investigated. Ag2O was substituted for CaO in the glass formula up to 2 mol% and in vitro bioactivity of the samples was evaluated by soaking them in simulated body fluid followed by structural characterization using XRD,FTIR and SEM techniques. The results showed that both glasses favored precipitation of the calcium phosphate layer when they were soaked in simulated body fluid;however, the morphology of apatite crystals changed for the 2% mol silver containing sample. Substitution of 2%mol Ag2O for CaO seemed to slightly stimulate the rate of precipitation. The in vitro biodegradation rate of the silver/calcium silicophosphate glasses was lower than that of the silver-free one (control). Also, the antibacterial properties of the samples indicated that these effects were improved by increasing silver concentration in bioactive glass composition.

Effect of manganese (Mn) doping on the optical properties of zinc sulfide (ZnS) semiconductor nanocrystals

Mohammadreza Tahriri,Elham Mohagheghpour,Mohammad Rabiee,Fathollah Moztarzadeh 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.2

In this research, we report the synthesis of ZnS nanocrystals with a size range of 1-10 nm in diameter with varying manganese (Mn) concentrations. Various samples of Zn1-x MnxS, with x = 0.0001, 0.007, 0.02, 0.03, 0.055, 0.09 and 0.13, have been prepared from a quaternary W/O microemulsion system. It is observed that by adding Mn to ZnS nanoparticles, the emission intensity changed and by using 5.5% magnesium for total Zn+2, a maximum emission were achieved. A photoluminescence (PL) study was carried out by band-to-band excitation (λex = 293 nm and 321 nm) upon ZnS : Mn, which results in two emission peaks corresponding to surface states and Mn+2 emission. Also, we observe orange emission from Mn2+ ions in the doped ZnS nanocrystals, apart from the blue emission characteristic of the ZnS defect states. The relative intensity of the orange emission compared with the blue varies with the manganese concentration in a nonmonotonic way. For analyses of the quality and quantity of this product, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), inductive coupled plasma (ICP), and spectrograph techniques were used.

Association of a Synthetic Bone Graft and Bone Marrow Cells as a Composite Biomaterial

S. M. Rabiee,S. M. J. Mortazavi,F. Moztarzadeh,D. Sharifi,F. Fakhrejahani,A. Khafaf,S. A. Houshiar Ahmadi,N. Nosoudi,R. Ravarian 한국생물공학회 2009 Biotechnology and Bioprocess Engineering Vol.14 No.1

Porous calcium phosphates have osteoconductive properties. The aim of this study was to obtain synthetic calcium phosphate bone graft substitute. X-ray diffraction was employed to investigate the formation of the beta-tricalcium phosphate (β-TCP) phase. We evaluated the effects of bone marrow on the osteoconductivity and mechanical properties of synthetic bone graft (SG). SG cylinders loaded with bone marrow (SGBM) and SG alone were implanted into rabbits femoral condyle bone defects. Histological examinations revealed the resorption of the SG, trabecular bone with osteoblasts and osteoid substance around the implants, and colonization inside the porous β-TCP by newly formed bone. Histomorphometry conducted after three months revealed the osteoid surface to be higher in SGBM than SG (p < 0.05). The compressive strengths of SG and SGBM were significantly higher than the anatomic control at all time periods. The elastic modulus of SBG and SGBM became weaker after implantation. The present results indicate that β-TCP is a good matrix for bone marrow, which contributes osteoinductive properties in an orthotopic. The composite biomaterial may be useful in reconstructive bone surgery.

Mechanical Behavior of a New Biphasic Calcium Phosphate Bone Graft

S. M. Rabiee,S. M. J. Mortazavi,F. Moztarzadeh,D. Sharifi,Sh. Sharifi,M. Solati-Hashjin,H. Salimi-Kenari,D. Bizari 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.2

The aim of this study was to create a new porous calcium phosphate implant for use as a synthetic bone graft substitute. Porous bioceramic was fabricated using a foam-casting method. By using polyurethane foam and a slurry containing hydroxyapatite-dicalcium phosphate powder, water, and additives, a highly porous structure (66 ± 5%) was created. The porous specimens possess an elastic modulus of 330 ± 32 MPa and a compressive strength of 10.3 ± 1.7 MPa. The X-ray diffraction patterns show hydroxyapatite and beta-pyrophosphate phases after sintering. A rabbit model was developed to evaluate the compressive strength and elastic modulus of cancellous bone defects treated with these porous synthetic implants. The compressive mechanical properties became weaker until the second month post implantation. After the second month, these properties increased slightly and remained higher than control values. New bone formed on the outside surface and on the macropore walls of the specimens, as osteoids and osteoclasts were evident two months postoperatively. Considering these properties, these synthetic porous calcium phosphate implants could be applicable as cancellous bone substitutes.