Applied Mechanics and Materials Vols. 754-755

Abstract: This paper describes a design of industrial modelling process of bacterial cellulose production. The main factors for the economic unfeasibility of this production are raw material price, plant capacity and capital cost. The purpose of this modelling is developing, studying, and evaluating process control technology in order to achieve low-cost preparation and high biocellulose (BC) production in industrial scale. In this model, glucose, a simple carbohydrate has been chosen as the carbon source. The aerobic fermentation of Acetobacter xylinum is regulated at particular temperature and pH to ensure maximum yield production. This fermentation process involves six stages that are sterilization, inoculation, fermentation, treatment, waste removal and drying/freezing. Nineteen streams will control and monitor the whole processes. The waste will undergo treatment in NaOH tank followed by sedimentation tank and filtration process for removal. Meanwhile, the BC is purified through drying and freezing process to preserve the product from contamination. This design shows that modelling is a powerful methodology for predicting and prioritizing methods of re‐engineering an industrial process in order to achieve greater performance.

Abstract: A phosphate-free glass based on SiO₂-CaO was synthesized by a low temperature acid catalysed sol-gel route. The obtained material was evaluated by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The XRD analysis showed the sol-gel derived glass was amorphous in nature and crystallized when sintered at temperature above 900oC. The crystalline state was consisted of quartz and wollastonite phases. Meanwhile the infrared analysis showed typical transmission bands of monolith silica in the binary glass pattern. The bioactivity of the amorphous glass was investigated in vitro in simulated body fluid (SBF). The amorphous glasses were soaked in SBF for 1, 3 and 7 days. It is notable that the obtained results from FTIR, SEM and EDS analyses showed the deposition of spherical-shaped crystalline hydroxyl-carbonate-apatite (HCA) on the surface of the glass within 3 days of immersion in SBF solution. The HCA deposition was covered most of the surface after 7 days of immersion.

Abstract: A comparative study on the quality of crushed and uncrushed kenaf retting water is presented in this paper. A number of parameters used in the assessment of water quality are examined in this study, namely, pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), turbidity and suspended solids (SS). The results reveal that both crushed and uncrushed kenaf retting water samples do not fulfil the requirements stipulated in the effluent standards. In addition, the quality of crushed kenaf retting water is poorer compared to that for uncrushed kenaf retting water. Based on the results of this study, it is evident that the retting process adversely affects the physicochemical properties of water and therefore water treatment is necessary before the water is being discharged downstream into ponds, lakes and rivers.

Abstract: Apatite-wollastonite glass ceramics (AW) in bone regeneration and replacement applications have been seen as a favourable alternative to allografts and autografts. A-W has good biocompatibility, bioactivity, chemical stability and mechanical properties. In this study AW was used to fabricate 3D parts for bone applications by an indirect three dimensional printing (3DP) technique. Various powder blends of AW and maltodextrine (MD) were processed using the Z Corp 3D printing process, with two different liquid binder systems. The green parts were post-processed through using a heat treatment to burn off the binder and sinter the powder particles. Consistent results were obtained for all tested specimens in terms of density, porosity and shrinkage. The highest strength after sintering was 35.6 MPa.

Abstract: The objective of the study was to determine the degree of biocompatibility of leucite glass-ceramics that have been produced from local high grade silica sand in terms of cytotoxicity and mutagenicity assays. In the present study, the cyctotoxicity and mutagenicity were studied using the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay (MTT) and Ames Reverse Mutation. In the MTT assay, a dose response cytotoxicity of leucite sample was evaluated in L929 cells. The cells were treated with the concentrations of 6.25, 12.5, 25.0, 50.00, 100.00 and 200.00 mg/ml of the leucite sample for 24 hours. The cytotoxicity was determined by assessing the cell viability through the reduction of tetrazolium salts (MTT). The mutagenenicity of leucite sample was evaluated in S. typhirium TA98. TA100, TA1535, TA1537 and E. coli WP2 in the Ames Reverse Mutation assay. Mutagenic effects were evaluated by comparing the mean number of revertant colonies of each extract concentraction with mean number of revertant colonies of the negative control. In results of MTT assay evaluated that the leucite did not show a cytotoxic effect at all concentrations under the condition of the study. Ames Reverse Mutation assay result proven that the leucite sample did not demonstrate a mutagenic effect under the condition of this study with Salmonella typhimurium and Escherichia coli.

Abstract: The research and development of biomaterials have brought about new treatments in regenerative medicine. The research work presented in this paper focus on the use of Poly-Lactide-co-glycolide (PLGA) in the fabrication of patient specific fracture fixation plate by indirect additive manufacturing method. The use of biopolymers such as PLGA has been seen as a solution to the problems of stress shield and post-surgery inherent in biometal fixation plates. This paper discusses the consequence of this processing method on characteristics and properties of the PLGA. PLGA of ratio 50:50, 65:35 and 85:15 was processed and compared. The granules of PLGA were positioned in the cavity of the stereolithography (SLA) mould and heated under constant pressure with sintering temperature of 73°C for 2.0hours. Both the variation in samples fabricated from this process with the designed model and the changes in material characteristics are below 10%. The flexural strength for PLGA of ratio 50:50, 65:35 and 85:15 is 73.8±2.3MPa, 75.0±2.8, 60.0±11.7, respectively. The characteristics and mechanical tests indicate that the results were comparable with conventional processing of PLGA.

Abstract: Edible bird nest (EBN) is a product obtained from the salivary excretion of different species of swiftlets during the breeding season. It is an expensive health food product. The raw EBN needs intensive cleaning before it can be consumed. Currently, EBN is increasingly used in cosmetic products. The cleaning procedure generally produced about 30 % (w/w) of waste. To date, there is no work conducted to study the composition of the waste recovered from the cleaning process and converting the waste into useful downstream products. Therefore, the aim of this study is to determine the composition of the EBN wastes and to formulate a value added facial cream product from the EBN waste. EBN waste (residues) was collected from the cleaning water of EBN samples from the swiftlet species Aerodramus fuciphagus using the centrifugation method. The chemical composition of the EBN waste (residues) was analyzed qualitatively using the FTIR technique. Similarly, the different grades of processed EBN samples (2A, 3A, 4A, 5A and biscuit white) from the swiftlet species Aerodramus fuciphagus were quantitatively analyzed using the elemental analyzer. The residual EBN showed high protein content (47.33±3.09 %) and carbohydrate content of 2.4±0.37 %. Interestingly, nitrite, nitrate and lead were not present in the EBN waste. Thus, EBN waste is considered safe to formulate a facial cream. The collagen content in EBN is good as an anti-aging beauty cream. Since the EBN is a very expensive product, the residual EBN waste has good potential to formulate a value added product without any loss in its nutritional health benefits to achieve a similar effect as EBN. The high protein content retained in EBN waste makes the wash off water from EBN washings a suitable nutrient – rich component for the formulation of health and beauty products.

Abstract: Mg-HAP Composite produce by powder metallurgy (PM) methods is one new biomaterial usually applied as biomedical implant. However, the sensitive Mg metal to surrounding environment is giving the bad impact for this biomaterial because of the presence hydroxyapatite particle in Mg matrix. The aim of this work is to study the corrosion behavior and microstructural evaluation of composite biomaterial Mg with different percentage of Hyroxyapatite (HAP) (5, 10, 15 and 20 wt. %) produced by powder metallurgy (PM) method. The corrosion test was done using electrochemical methods and the microstructure after corrosion test was observed using optical microscope. Based on the results, the different percentages of HAP were influenced the corrosion rate of the Mg-HAP composite. The percentage of HAP content in Mg were greatly influences the corrosion behavior of the alloy. Sample Mg-20wt% HAP has the lowest corrosion rate which is 0.16mm per year, while sample Mg-15wt% HAP has the highest corrosion rate, 0.37 mm per year.

Abstract: Co-crystallization process has been used in pharmaceutical industry in producing new class of API solids due to its advantages such as physical stability and solubility.The objective of this study is to characterize the co-crystal formation of ibuprofen with saccharin as a co-crystal former through wet milling by using XRD, FTIR and DSC. A study of co-crystal formation from ibuprofen and saccharin has been conducted by using wet milling with the presence of solvent. The PXRD results showed a new phase which is believed a new crystalline has been successfully formed. The DSC analysis showed a new melting point for the new phase. However, the functional group assessment showed the presence of an unknown functional group in the system.

Abstract: This study was undertaken to characterize pyrolysis of novel biobased invasive weed from Imperata Cylindrica. The effects of various temperatures on the pyrolysis stages were characterised. Different operational parameters such as pyrolysis temperature, heating rate temperature are studied. Pyrolysis experiment of groud Imperata Cylindrica was performed at temperature 350°C, 550°C and 750°C, and particle size of 0-125μm and heating rate of 5°C/min and 15°C/min. The synthesis carbonaceous was characterized by Fourier Transform Infrared Spectroscopy (FTIR), and different physical properties such as carbon yield, Carbon Hydrogen Nitrogen (CHN analysis), and X-Ray Fluorescence (XRF) was determined. It is observable that pyrolysis at the 15°C / min with 750°C shows that higher temperature produced a higher carbon yield and higher carbon content.