Advanced Materials Research Vol. 1133

Abstract: The purpose of this study was to prepare biphasic granules containing gypsum and carbonated apatite at low temperatures. The biphasic granules were prepared using dissolution-precipitation technique at three different temperatures 30°C, 40°C and 50°C. Characterization of the biphasic granules was determined by multiple analytical methods such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infra-red (FTIR), and CHN Analysis. The obtained granules were determined by XRD as biphasic granules containing bone apatite and gypsum. The cross-section of biphasic granules was observed by SEM. The formed bone apatite was identified as B-Type carbonated apatite using FTIR The carbonate content in biphasic granules fabricated at 30°C, 40°C and 50°C were recorded by CHN analysis as 5.0 wt%, 6.1 wt% and 6.25 wt%, respectively.

Abstract: This paper work proposes the idea of super hydrophilic chitosan development in porous sponge form as the bottom part of bi-layer skin regenerating template. In this experiment, 5 different ratios of chitosan: methylcellulose have been prepared by varying the amount of methylcellulose from 10 %, 20 %, 30 %, 40 %, to 50 %. The formation of chitosan-cellulose scaffold will be carried out through combination of moist providing methylcellulose and wound-healing chitosan. The advantages of using methylcellulose on hydrophilicity of the template was characterized through FTIR analysis and wettability study, while their morphology was characterized using Variable Pressure Scanning Electron Microscope (VPSEM). The polymeric structure of polyanion methylcellulose which contains hydroxyl (-OH) functional group, analyzed using FTIR analysis was expected to attract H2O molecule from the moisture, hence providing the hydrophilic properties of the polymer. Water uptake study shows that as the percentage of methylcellulose used in the template increased, the water uptake of the template also increased. However, increasing the amount of methylcellulose did not give a significant different to the porosity of the template.

Abstract: A carbonated apatite (CO₃Ap) has a closer chemical composition to the bone mineral which may be suit as an artificial bone substitute. In this study, the fabrication works of biphasic gypsum-carbonated apatite granules has been done through the phase transformation by carbonation and phosphorization of the gypsum granules. Gypsum also known as calcium sulphate dihydrate (CSD) granules was immersed into the 2 M of carbonate and phosphate salt solution at 50 °C and room temperature in variable time. The effect of time on the fabrication of biphasic granules were studied using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier transform infrared (FTIR). The XRD analysis was done to confirm the formation of gypsum and hydroxyapatite phases in the biphasic granules. The FTIR spectroscopy indicated that the formation of carbonate apatite was formed in these biphasic granules. The cross sectional morphology of the biphasic granules was observed using SEM. The compositional elucidation was quantitatively measured by CHN analysis to obtain the contents of CO₃.Based on the results obtained, it is observed that the CSD was successfully transformed into carbonated apatite to form biphasic granules and time had influenced on the fabrication of these biphasic.

Abstract: The emerging of bacteria/cell culturing in biological/biomedical research and industry is in demand for low cost, fast, non-invasive, and reliable alternative/approach for evaluation and measurement. Microfluidic approach is one of the promising alternatives for replacing the expensive commercial cuvvete for bacteria/cell culture and suspension for optical measurement. This study demonstrates the integration of absorbance measurement with microfluidic platform for Escherichia coli (E. coli) bacteria suspension analysis. The E. coli was cultured and prepared for suspension medium which then transferred inside the PDMS-glass based microfluidic. Then, the absorbance measurement is carried out using UV-Visible spectrophotometer. We demonstrate this method by measuring absorption of light transmitted through microfluidic chambers within the visible light range (350nm - 750nm). From the result, it had indicates that the graph pattern and growth behavior of E. coli suspension in microfluidic platform are reliable and comparable to commercial cuvvete reading. This finding

Abstract: Total hip replacement (THR) is a flourishing orthopaedic surgery which generating billion of dollars of revenue. The cost associated with the fabrication of implants has been increasing year by year and this phenomenon has burdened the patient with extra charges. Consequently, this study will focus on designing an accurate implant via implementing the reverse engineering of three dimensional morphological study based on a particular population. By using the finite element analysis, this study will assist to predict the outcome and could become a useful tool for pre-clinical testing of newly designed implant. A prototype is then fabricated using 316L stainless steel by applying investment casting techniques which reduce manufacturing cost without jeopardizing implant quality. The finite element analysis showed the maximum von Mises stress was 66.88 MPa proximally with a safety factor of 2.39 against endosteal fracture, and micromotion was 4.73 μm which promotes osseointegration. This method offers a fabrication process of cementless femoral stems with lower cost, subsequently helping patients, particularly those from non developed countries.

Abstract: The aim of this work was to study the effect of milling time on binary magnesium-titanium (Mg-Ti) alloy synthesized by mechanical alloying. A powder mixture of Mg and Ti with the composition of Mg-15wt%Ti was milled in a planetary mill under argon atmosphere using a stainless steel container and balls. Milling process was carried out at 400 rpm for various milling time of 2, 5, 10, 15 and 30 hours. 3% n-heptane solution was added prior to milling process to avoid excessive cold welding of the powder. Then, as-milled powder was compacted under 400 MPa and sintered in a tube furnace at 500 °C in argon flow. The refinement analysis of the x-ray diffraction patterns shows the presence of Mg-Ti solid solution when Mg-Ti powder was mechanically milled for 15 hours and further. Enhancements of Mg-Ti phase formation with a reduction in Mg crystallite size were observed with the increase in milling time. A prolonged milling time has increased the density and hardness of the sintered Mg-Ti alloy.

Abstract: Cobalt-chromium alloys are commonly used for surgical implants because of their high strength, superior corrosion resistance, non-magnetic behavior, and biocompatibility. Cobalt-Chromium-Molybdenum (Co-Cr-Mo) applications include prosthetic replacements of hips. This paper presents the attempt to produce metallic implant using Co-Cr-Mo powder by MIM process, focusing on the effects of different heating rate during sintering process at 1380°C. Co-Cr-Mo powder were mixed homogeneously with palm oil and conventional binders respectively with powder loading 65 vol% and was injection molded using vertical injection molding machine with the nozzle temperature of 160°C to produce green compacts. The binders then was removed by solvent extraction process and sintered in vacuum condition at atmosphere 10^-5 mbar at temperature 1380 °C with varied heating rate; 0.5°C/min, 1.0°C/min and 3.0°C/min . Results indicated that sintered density and tensile strength varied from 8.100 gcm^-3 to 8.200 gcm^-3 and 546.971 MPa to 798.767 MPa respectively. The mechanical properties comply with the international standard (ASTM F75).

Abstract: Their excellent properties, such as corrosion resistance, fatigue strength and bio-compatibility, made Cobalt-chromium-molybdenum (CoCrMo) were used in total hip and knee replacements and dental devices. The green CoCrMo compacts specimens in rectangle shape were fabricated by powder pressing technique. The effects of sintering temperature and atmosphere on the mechanical properties and microstructure of the CoCrMo compacts which is sintered at 1300°C-1400°C under two different inert gases sintering atmosphere (Ar₂/N₂H₂) were investigated. The experimental results show that the grain boundaries sizes of CoCrMo compact sintered specimen were increased with increasing sintering temperature. The CoCrMo compacts specimens sintered at 1350°C under inert gases N₂H₂ atmosphere possess highest density (8.096 g/cm³) and hardness (327.1Hv). However, when the compacts specimens are sintered at 1400°C, the density (7.596 g/cm³) and hardness (320 Hv) properties of sintered compact were decreased.

Abstract: Powder injection molding (PIM) process is suitable for both metal and ceramic materials to produce parts with high volume and accuracy at low cost. In this research work, 90wt. % of Ti6Al4V was dry mixed with 10wt. % of Hydroxyapatite (HA). The resultant mixture was further mixed with different space holders in weight ratio 8:2. The feedstock was prepared by mixing the final mixed powder with PEG and PW based binder systems. The dumbbell shape parts were produced using DSM Xplore injection molding machine. The molded samples were debound into two stages i.e solvent extraction followed by thermal debinding. The debinding parameters were optimized for different binder with space holders. The major binders’ paraffin wax (PW) extracted in haptane and PEG in water immersion at temperatures of 60 °C and 50 °C for 5 hrs respectively. The thermal de-binding was performed successfully at 500 °C by varying the heating rate from 3 °C/min-5 °C/min with holding time 1hr in argon atmosphere followed by the sintering in vacuum. During molding short shot defects and cracks were observed while during debinding, collection of binder, swelling and holes were noted. These types of defects may be due to space holder, improper binder, heating rate, temperature and dwell time at each processing step. The sintered test specimens were analyzed for porosity and microstructure. The results showed that the PEG based binder system with NaCl space holder is more effective to produce porous Ti/HA composite through PIM. Porous Ti/HA composite showed interconnected pores with average size of 90µm.

Abstract: In the past few decades, Metal Injection Moulding (MIM) has evolved as a new revolutionary metalworking process for medical implant fabrication in orthopaedics. The technology employs natural resources in a minimum outlay without compromising the quality of its end products. This metalworking process allows the production of a high volume complex prosthetic implants that can be shaped in a single operation and cost productive. In this study, we evaluated the potential of MIM 316L stainless steel as the internal fixation plate in a long bone fracture using rabbit model. The study was approved by the International Islamic University Malaysia Research Ethics Committee. Experimental fractures were made at the rabbits’ tibia and fixed with either MIM plate or AO/ASIF mini plate, as control. The assessments were carried out by means of radiography procedure and histological evaluation at each time point of 3, 6, 9, 12 and 26 weeks post-operatively. Hard tissue processing was used since all samples comprised bone tissue and metal plate. Based on the observation, there were callus formations in both MIM and control groups at week 3 post-operatively. Bone union was evidenced starting week 6, whilst bone remodelling was completed at week 26. Histological assessment indicated that both groups possessed mild to moderate callus bridging at week 3 and week 6, respectively. While complete remodelling bone cortex was evidenced at week 26. Taken together, these findings indicate that the potential of MIM plate to hold the tibial fracture is comparable to that of AO/ASIF plate. Apart from being cost productive, the production of MIM plate also utilizes natural resources. Therefore, the MIM plate can be used as an alternative internal fixator for bone fracture management in orthopaedic.