Papers by Keyword: SBF

Abstract: Developing Mg based implants for temporary applications based on their biodegradation in the physiological environment is a potential research area in the biomedical engineering. Assessing the bio-corrosion in simulated conditions helps to reduce the complexity of research studies associated with in-vivo experiments and can be used to assess the true behavior of the Mg implant in artificial solutions. On the other hand, assessing the corrosion behavior by using 3.5% NaCl solution is a standard ASTM protocol widely used in the industries. Hence, in the present work, degradation of pure Mg due to bio-corrosion in two different solutions i.e simulated body fluids (SBF) and 3.5% NaCl solution has been investigated. From the results, the weight loss measurements indicated higher degradation during the initial 24 h in SBF solution. However, with the increased immersion time to 72 h, due to the deposition of mineral phases from SBF as confirmed from the electron microscopy and X-Ray diffraction study, the degradation was observed as decreased in SBF compared with NaCl solution. Hence, the results demonstrate that the evaluation of degradation behavior of Mg based materials in simulated physiological environments is appropriate compared with the standard NaCl environment.

Abstract: Using the sol-gel process, glass powder was made. After the preparation method of the glass powder, x-ray analytical (XRD), particle size analysis and Fourier Transform Infrared (FTIR) were performed. The particle size analysis of manufactured glass (13-93) is found to be about 2.978 μm. (XRD) mode analysis suggested that the resulting porous scaffolds were amorphous. Using the process of salt leaching to create bioactive glass scaffolds (13-93) with structural and physical properties suitable for the human trabecular bone. XRD spectroscopy, scanning electron microscopy (SEM) and FTIR after sintering at temperature 750 °C were used to investigate the microstructure and chemical bonding of the porous scaffolds. The synthesized scaffold was soaked in medium of the simulated body fluid (SBF) and examined by SEM and XRD analysis in order to evaluate bioactivity. From the SEM morphology analysis results, it was noticed that the scaffolds comprised open and interconnected pores with a porosity range of 75-78%. High bioactivity of pours scaffolds was reported to have been observed after soaking 7days in SBF media because of the formation of apatite layer on its surfaces. Keywords: bioactive glass (13-93), scaffold, salt leaching method, SBF, sol-gel.

Abstract: Synthesis and characterization of bioglass^® of general composition (45-X-Y) SiO₂, 24.5 Na₂O, 24.5 CaO and 6.0 P₂O₅ (wt %) was modified by addition of X= (0-1) wt % of CeO₂ and Y= (0-1) wt % of La₂O₃ respectively. These five samples were prepared in alumina crucible via melting route at a temperature of 1400±5 °C with air as a furnace atmosphere. These glass samples were immersed in simulated body fluid (SBF) for different time period and their bioactivity were determined by Fourier transform infrared spectroscopy (FTIR) analysis. Surface morphology was studied by using Scanning electron microscope (SEM). Bioactivity, pH measurement of bioactive glass was carried out and mechanical properties of these glasses increased with increasing concentration of CeO₂ and La₂O₃.

Abstract: In order to make good use of the previous design knowledge, the knowledge-based engineering ideas were introduced to the design of airfoils for variable-pitch wind turbines, a new design method for airfoil of wind turbine was formed. Firstly, the structure-behavior-function (SBF) model of airfoils design was derived. Secondly, the neural rules for airfoils design of variable-pitch wind turbines were deduced. Thirdly, the design method of airfoils structure for wind turbines based on case-based-reasoning (CBR) was establishment. And the dimensionless model based on case representation was set up, and the algorithm of geometric parameters design for airfoils based on CBR was proposed at last.

Abstract: Pure Mg and AZ91D alloy was anodized with and without the gadolinium nitrate Gd (NO₃)₃ in different concentrations (0.001g/l, 0.025g/l, 0.05g/l, 0.075g/l and 0.09g/l) at a constant current density and treatment time of 10mA/cm² and 5 minutes. The results showed that the optimum gadolinium concentration is 0.075g/l due to obtaining the anodic film with high corrosion resistance. The surface morphology and microstructure of anodic coating were investigated by scanning electron microscopy (SEM) , optical microscope (OM), and potentiodynamic polarization, respectively.

Abstract: Hydroxyapatite is a bioceramic material of great interest for use as bone substitute because of its similarity with the composition of biological apatite. Cationic and anionic substitutions in the apatite structure have been made in order to optimize the synthesis and accelerate the process of bone repair. In the present study, niobate apatite was synthesized by a patented aqueous precipitation method. The bioactivity of the samples was assessed by X-ray diffraction analyses (XRD), energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy with field emission gun (FEG-SEM; FEI Quanta FEG 250) in the samples before and after an incubation period in simulated body fluid. The results showed that after 3 days a bone-like apatite coating was formed onto the niobate apatite surface. A peculiar morphology comprised by nanosized wires was also observed on the niobate apatite surface.

Abstract: In the present study, the in vitro bioactivity of silver-doped hydroxyapatite (HAp/Ag) scaffolds was investigated. HAp/Ag was prepared using two different modified wet precipitation methods. The X-ray powder diffraction (XRD) results showed, that sintered HAp/Ag samples prepared using method (I) contain two phases HAp and Ag, but samples prepared by method (II) contain three different phases - HAp, Ag and AgO. After 2 month incubation period in simulated body fluid (SBF), surface of HAp/Ag scaffolds was coated with bone-like apatite. Thickness of bone-like apatite layer increased from 2 μm up to 32 μm, increasing the incubation period.

Abstract: The mineral or inorganic component of bone is a calcium phosphate idealized as a calcium hydroxyapatite, HA, Ca₁₀ (PO₄)₆(OH) ₂. Changes in the composition of the apatite affect its lattice parameters, morphology, crystallinity (reflecting crystal size and/or perfection) and finally dissolution properties. In regard to the above points, lattice parameters are expected to have better dissolution properties. Estimation of HA nanocrystallite size lattice parameters is one of the most important factors for dissolution properties of bone apatites. In present work, the composition of apatite induce complex structures at the unit-cell level and play a role in influencing the dissolution rate of apatites, which may favour osteointegration. The samples are consist of NHA, bovine bone heated at 850 °C for 3 h; BHA, human bone heated at 900 oC for 2 h and PHA, HA pure powder. The results estimated by XRD data indicate that increasing in c/a ratio of HA, which is leading to increasing in crystallinity, induce decrease at HA dissolution or improving its chemical solubility in simulated body fluid (SBF). As, it was concluded that the biodegradation of HA decrease in PHA sample.

Abstract: The clinical use of plasma-sprayed hydroxyapatite (HA) coatings on metal implants has been widely investigated as the HA coating can achieve the firm and direct biological fixation with the surrounding bone tissue. It is shown in previous studies that the mechanical properties of HA coatings are improved by the addition of ZrO2 particles during the deposition of the coating on the substrate. Subsequently, the cohesive and adhesive strengths of plasma-sprayed hydroxyapatite (HA) coatings were strengthened by the ZrO2 particles addition as a reinforcing agent in the HA coating (HA+ZrO2 composite coating). The aim of the present work is to investigate and evaluate the in vitro bioactivity assessment of HA and HA/ZrO2 coatings, on stainless steel substrate, soaked in c-SBF, in order to study and compare their biological responses. The coatings were produced using vapor plasma spraying (VPS). The characterization of the surface of the coatings before and after soaking in SBF solution was performed using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-ray Diffraction analysis (XRD). All samples were smoothed before insertion in the medium and the in vitro bioactivity of all coating samples was tested in conventional Simulated Body Fluid (c-SBF) solution for various immersion times.

Abstract: Results of the present study provide strong indications towards the effective application of the 110oC Thermoluminescence (TL) peak in discriminating between different bioactive responses for the case of the 58S bioactive glass. The in vitro bioactivity of this glass in the form of powder in SBF solution was tested for various immersion times, ranging between 0 and 6 days. This TL peak is ubiquitously present in all 58S samples, for all immersion times. The intensity of the110oC TL peak was proven to be very sensitive to the different bioactive responses, indicating a strongly decreasing pattern with increasing immersion time in SBF, easily identifying thus the loss of silica. This loss is reflected to the decrease of the 110oC TL peak intensity, which appears to be fast even for the shorter immersion times. The 110oC TL glow peak intensity and sensitization could also be yielding a time scale regarding the beginning of some among the several stages included in the bioactivity sequence.