|BIODEGRADATION EVALUATION OF POLY(3-HYDROXYBUTYRATE-CO-3-HYDROXYVALERATE (PHBV) RESINS
A bio-nanocomposite poly (3-hydroxybutyrate-co-3 hydroxyvalerate) (PHBV)/Nanocrystalline cellulose (NCC) blends with inclusion of 10 % (w/w) of surface modified NCC was prepared with the mass proportion of 90/10 using a melt mixed technique. However, despite its superior properties, PHBV also has its disadvantages due to its nature of being a highly crystalline polyester which exhibits stiffness and brittleness. This less desired traits restricts their application in many fields. To overcome this, the most efficient and economical approach is to incorporate polymer blends (nanofiller) of different polymers, such as NCC that have could enhance the mechanical properties compared to the original polymers as well as improve the impact strength at low temperature and heat resistance. However, the biodegradation rate of PHBV/NCC based to our best knowledge, has not been widely studied. In this paper, the biodegradability of PHBV/NCC was tested under a laboratory-scale controlled composting using Microbial Oxidative Degradation Analyser (MODA) according to ISO 14855-2:2007. Biodegradation evaluation was performed at 58 oC using compost derived from agricultural waste. The degree of biodegradation of PHBV/NCC was measured by measuring the carbon dioxide evolved. It was observed that the biodegradable rate was 77.10 % after 180 days incubation. PHBV/NCC was also concluded to be a biodegradable polymer with the degradation percentage of 94.76 %, relative to cellulose as a reference material based on ISO 17088:2008 and EN13432:2000.
Keywords: Bio-nanocomposite, PHBV/NCC, Biodegradation, Laboratory-scale
|A REVIEW OF WIRELESS POWER TRANSFER SYSTEM USING INDUCTIVE AND RESONANT COUPLING
Wireless Power Transfer (WPT) using Magnetic Resonance Coupling (MRC) caught the significant attention from the researchers in academia and industries worldwide due to its higher power transfer efficiency especially at medium distances. In this regard, various circuit topologies have been proposed for further improving the efficiency. This review emphasizes the efficiency analysis of WPT system using circuit equations. This literature survey covers the two, three and four coils WPT system. In addition, review of multiple coils WPT structure is also presented. Frequency decrease analysis, impedance matching and frequency splitting phenomenon are also discussed. The two operating principles, maximum power transfer and maximum energy efficiency are described. This is followed by safety standard for WPT technology. Finally, a comparison of Inductive Wireless Power Transfer (IWPT) and Resonant Wireless Power Transfer (RWPT) is provided. This review will be helpful for the readers to understand the circuit structures and operating principles of the WPT technology.
Keywords: Wireless Power Transfer (WPT), Magnetic Resonance Coupling, Frequency Splitting, Efficiency Analysis, Maximum Power Transfer, Maximum Energy Efficiency.
|DESIGN AND FABRICATION OF PATIENT SPECIFIC ORBITAL FLOOR IMPLANT USING 3D METAL PRINTING
Patient Specific Implants for the reconstruction of maxillofacial defects have gained importance due to better performance over their generic counterparts. An orbital fracture is a traumatic injury to the bone of the eye socket, usually occurring because of blunt force trauma to the area surrounding the eye. Orbital rim fractures refer to injury to the bony outer edges of the eye socket and it takes a great deal of force to make them occur, such as in car accidents. This paper will present the study of design and fabrication of orbital implant using 3D metal printing technology. Application of Medical Software to translate patient’s Computed Tomographic Scanning (CT Scan) data into 3D modelling is assisting the way surgeons are planning surgeries and design engineers are designing the Patient Specific Implant of the orbital fractures. Advances in manufacturing process such as 3D metal Printing technology for custom implant production has eliminated the constraint of shape, size and internal structure and mechanical properties making it possible for the fabrication of custom implants that conform to the physical and mechanical requirements of the region of implantation. Pure titanium is used for the fabrication of patient specific orbital floor implant. The validation process is done using a 3D printed model of the orbital defects area with the reconstruction of orbital floor custom implant model. The deviation analysis is carried out to study the accuracy of the manufactured custom implant. The implementation of the 3D metal printing technology for implant shaping and intraoperative assessment of reconstruction leads to improve aesthetic appearance which could essentially improve patient outcomes.
Keywords: 3D modelling; Patient Specific orbital floor implant; 3D Titanium Printed; 3D printing technology
|A REVIEW ON GEOPOLYMER AS A NEW GREEN COATING MATERIAL
For many years, researchers have been working on the sustainable ways to protect metals and infrastructures from deterioration, but recently new regulations related to the health safety and environment has driven the attention of the research community to introduce green alternatives to conventional coatings. Serious implementation of the conventional coatings include the release of VOCs lead to a greenhouse effect, ozone layer depletion and health related issue including asthma, bronchitis and sometimes skin and lung cancer. To reduce such impacts, conventional coatings are replaced by water-based alternatives and inorganic coatings. In the past few decades, geopolymers have been materialized as a potentially new material with interesting properties and applications. A review on geopolymers about the history, properties, applications and limitations of geopolymer is discussed. Some preliminary results are provided.
Keywords: Coatings, corrosion resistance, geopolymer
|PEGYLATED PAMAM ENCAPSULATED FREE-CD QUANTUM DOTS AND THEIR CELLULAR UPTAKE STUDY
Quantum dot with unique optical properties has been extensively studied for the cellular and assay labelling in biomedical applications. The existing cadmium quantum dot was already known as highly toxic towards living cells as the release of cadmium ion will poison the cells. Thus, a free-cadmium quantum dot is needed in order to overcome this limitation. However, it is a challenge to deal with the solubility of quantum dot as it is only soluble in organic solvent such as n-hexane or toluene. Therefore, indium phosphide/zinc sulfide quantum dot, known as InP/ZnS quantum dot, will be used as it has shown some fluorescent intensity and was comparable to cadmium quantum dot. Due to that, the ligand exchange method was used to prepare water soluble InP/ZnS quantum dot that is suitable for biomedical application. In our work, PEGylated poly(amidoamine), or known as PEGylated PAMAM, was prepared and InP/ZnS quantum dot was entrapped into the internal cavity of the PAMAM. The cell viability and cellular uptake of InP/ZnS qantum dot and PEGylated PAMAM-InP/ZnS quantum dot were studied towards cancerous and
non-cancerous cells. The result shows that both samples are less toxic towards these cells. Hence, tailoring this PEGylated PAMAM-InP/ZnS quantum dot with biomarker will be potentially useful for cell imaging studies.
Keywords: Quantum dot, fluorescent, cell viability, cellular uptake, bioimaging
|PULSE PRESSURE OSMOTIC DEHYDRATION (PPOD) METHOD FOR SALTED EGG MANUFACTURING USING 3D-PRINTED POLYMER PRESSURE CHAMBER
Salted egg is a popular delicacy for Asian populace originated from ancient Chinese recipe. The current method of production is through preservation using red soil and brine coating which can take a minimum of 2 weeks before reaching the threshold of saltiness acceptation. Recent research shows that the introduction of Pulse Pressure Osmotic Dehydration (PPOD) method will be able to reduce the absorption time. This innovation is faster and more effective than the making of salted egg by using traditional salting. The focus is on the use of air pressure chamber prototype generated using 3-dimensional printing technology which was Selective Laser Sintering (SLS). The usage of 3D Printed air pressure chamber with different combination of NaCl-H2O and pulse strategy to the egg specimen, identifies time taken in reaching the threshold value (based on commercially available salted eggs) of salt absorption. The preliminary result shows that this method is capable of shortening the osmotic dehydration time for egg salting.
Keywords: Salted egg, Additive Manufacturing, Selective Laser Sintering, Pulse Pressure Osmotic Dehydration.