Advanced Materials Research Vol. 1024

Abstract: In this report, we discussed the physical properties of encapsulated Methylene Blue (MB) by Silica Nanoparticles (SiNPs) intended for photodynamic therapy application. The aim of this discussion is to determine the suitable concentration of MB which can be delivered to the target area. Results shows that the size of SiNP is not affected by the change in MB concentration from out-diffusion process even when the concentration of loaded MB were reduce by more than 50 percent. The applicability of the encapsulated MB in SiNP was demonstrated on Red Blood Cells (RBCs) and the results were compared to those obtained from naked MB.

Abstract: Poly (vinyl alcohol) (PVAL) was a common stabilizing agent used in formulate polymeric drug encapsulated micro-/nanoparticles. In preparing poly (lactic acid) (PLA) micro-/nanoparticles by emulsion and solvent evaporation (ESE) technique, the particle size and distribution have shown dependent on PVAL concentration. The focused of this project was to investigate the PVAL function in relation to significant changes in particle size. These studies were relatively important, as it was the basic studies of material usage in ESE fabricating process. The function of PVAL as, either surfactant that able to reduce interfacial tension or stabilizer to provide steric stability was further investigated by measuring the interfacial tension (IFT) of two liquids and zeta potential of the particles. As PVAL concentration increased, the reduction of IFT was only pronounced at the early stage of PVAL incorporation from 16.02 m N/m (absence of PVAL) to 2.0 m N/m (presence of 1 % PVAL), while zeta potential of particles was gradually decreased from-25 mV to-10.2 mV. As conclusion, the presence of PVAL could reduce the interfacial tension. However, to further stabilize the particle (e.g. reduce size and narrow size distribution) in the fabrication process, the steric stabilization provided by PVAL give more significant advantages.

Abstract: Superparamagnetic iron oxide nanoparticles (SPION) are routinely employed in biomedical and water treatment applications due to their inherent magnetic properties. However, for these applications a surface modified and functionalized SPION is required. Herein, for the first time we present an in-situ method of functionalizing decanethiol monolayer on thin silica coated SPION synthesised via a non-seeded process. Through physico-chemical analyses the grafting of decanethiol onto the composite nanoparticles were demonstrated. The alkane functional group in the monolayer molecule attached to the silanol group of the silica shell and became the tail and binding site to the magnetic composite nanoparticles.

Abstract: In this study, Ti-30at.%Nb was subjected to solution annealing at 900°C followed by ageing at 300^o, 400°C, 500°C and 600°C for one hour in order to investigate the effect of ageing temperature on the microstructures and mechanical properties behaviour. It was found that the microstructures of the sample in solution anneal consists of β austenite phase. This indicates that the transformation temperature, Ms, of the material is below room temperatures. The presence of other phases such as α phase and ω precipitates has been detected on the samples after ageing at 500°C and 600°C. Maximum hardness value and tensile strength obtained on the sample aged at 500°C was associated with the presence of ω phase, however the existence of α phase in the sample aged at 600°C provides the lowest hardness and tensile strength. The solution treated sample shows the best shape memory behaviour compared to other heat treated alloys. However, the best superelastic behaviour was observed on the sample aged at 300°C.

Abstract: The low Young's modulus of Ti-alloys is of particular importance for biomedical applications to prevent or reduce the occurrence of stress shielding. This paper shows some ways that are used to produce new Ti-alloys with low Young's modulus for biomedical applications. The different factors that affect the Young's modulus such as the phase's stability, role of alloying elements, plastic deformation, and texturing are discussed. The low-cost and low-Young's modulus Ti-alloys (i.e., alloys composed mainly of the common elements and/or contains a minimum amount of the high-cost rare elements) are also discussed.

Abstract: The effect of sintering temperature on the diametral tensile strength of β-tricalcium phosphate (β-TCP) block was investigated. Uniaxially pressed block of mixture of calcium hydrogen phosphate dihydrates (CaHPO₄2H₂O) and calcium carbonate (CaCO₃) were pressed at 5 MPa and sintered at 1000°C, 1050°C and 1100°C. XRD analysis revealed that single phase β-TCP was obtained at all sintering temperature. The porosity obtained from β-TCP block sintered at 1100°C was found to be lower than that sintered at 1000°C and 1050°C. Diametral tensile strength (DTS) value of β-TCP block sintered at 1100°C showed significantly higher value than β-TCP block sintered at lower temperature. It is therefore concluded that the increased in sintering temperature affects the mechanical strength of the β-TCP block.

Abstract: Micro sized gels have been widely used as drug carriers for its compatibility in blood. Among its important properties are round small dimensions and large surface area. These properties allow for better attachment of ligand and higher stability in the blood stream. In this study,microgels from polyethylene glycol diacrylate (PEGDA) were prepared from its microemulsions form using electron beam with energy of 3 MeVat different irradiation dose of 0 to 25 kGy. Dynamic light scattering (DLS) study revealed that gel with diameter of 70-100 nm with a narrow size distribution was obtained at 5 kGy and 400-550 nm with a broad size distribution at 25 kGy. The molecular weight obtained from GPC-MALLS for the minimum practical dose irradiated has resulted to more than 4.22 x 10⁵ g/mol as compared to7.75 x 10² g/mol forunirradiated polymer. The increase of size and its distribution as well as its molecular weight over the elevation dose were suspected to be due to diffusion of micelles that leads to recombination of macro radicals from different micelles during longer irradiation period at higher doses. Overall findings from this study have proven that PEGDA microgels can be prepared via electron beam radiation with emulsions as templates for polymerization.

Abstract: The differences in structural, compositional and photoelectrochemical properties for SnSe films annealed at different temperatures, under nitrogen atmosphere, were studied. Annealing the film electrode significantly improved its crystallinity but lowered its photoresponse. The photoresponse lowering was thus attributed to lowering in the defect concentrations.

Abstract: Polyaniline-doped with functionalyzed acetylene black material has been successfully synthesized and used as an electrode material in supercapacitor, wherein, this material contributes both pseudocapacitative (PC) and electrical double layer capacitative (EDLC) behaviour. Functionalization of acetylene black (AB) has been carried out and used as dopant for THF soluble polyaniline base (PANI) to prepare PANI-functionalized acetylene black (PANI-FAB). Formation of FAB and PANI-FAB was confirmed with the help of FT-IR and XPS study. Functionalization of AB results in agglomerated FAB and doping with PANI results in agglomerated fibrous PANI-FAB, as compared to fibrous AB. High thermal stability of AB decreases on functionalization and again slightly increases for PANI-FAB. Functionalization of AB also results good bonding effect with PANI, where PANI acts as both PC and binder, instead of the higher amounts of binder (PVdF > 30 wt%) that are normally needed to hold AB. Electrochemical studies of FAB and PANI-FAB materials were carried out by cyclic voltammetric and electrochemical impedance spectroscopic methods. PANI-FAB supercapacitor cell shows capacitance of 132 Fg¹ for 0.3 Ag¹ current density with very low charge-transfer resistance and low time constant.

Abstract: Lanthanide doped/based oxide thin films were deposited by liquid injection metal organic chemical vapor deposition or atomic layer deposition. Frequency dispersion is often found in the capacitance-voltage measurements. After taking the extrinsic frequency dispersion into account, the frequency dependence of the dielectric constant (k-value), that is the intrinsic frequency dispersion (dielectric relaxation) has been successfully theoretically modeled. For the physical mechanism of the dielectric relaxation, it was found that the effect of grain sizes for the high-k materials structure mainly originates from higher surface stress in smaller grain due to its higher concentration of grain boundary. Variations in the grain sizes of the samples are governed by the deposition and annealing conditions and have been estimated using a range of techniques including Scherrer analysis of the X-ray diffraction patterns. The relationship extracted between grain size and dielectric relaxation suggests that tuning properties for improved frequency dispersion can be achieved by controlling grain size, hence, the strain at the nanoscale dimensions.