Advanced Materials Research Vol. 832

Abstract: Topical ocular drug delivery has always been a challenging area due to poor ocular bioavailability. Improved drug delivery systems such as liposomes are capable of entrapping both the lipophilic and hydrophilic substances. Therefore, they are effective formulations for drug delivery to targeted structure. PEGylated-liposomes are known to have stealth properties due to their ability of resisting removal by phagocytic cells. This study compares ability of PEGylated-and nonPEGylated-liposomes in delivering lipophilic fluorescent dye, Dil, to several ocular tissues. Sprague-Dawley rats (190-250g) were divided into 2 groups that received unilateral topical application of single drop of PEGylated-liposome (PEG-Lip) or nonPEGylated-liposome (Lip). Contralateral eyes served as control and received no treatment. Animals were sacrificed at several time points, post-instillation, and eyeballs were enucleated. Cryostat sectioning was done and sections were viewed with fluorescence microscope. Fluorescence intensity (FI) was calculated and quantified. In treated eyes, nonPEGylated-liposomes showed faster corneal permeation compared to PEGylated-liposomes. NonPEGylated-liposomes also showed faster availability in ciliary body and retina of treated eyes, possibly a consequence of faster corneal permeation. Their higher engulfment by macrophages and subsequent localization in vascular tissue may also be a contributing factor. In contralateral eyes, both groups showed dye distribution indicating their significant systemic distribution. Higher availability of non-PEGylated-liposomes in contralateral eyes also indicated that they are more likely to undergo phagocytosis and consequently faster removal. In conclusion, PEG-lip showed slower corneal permeation in the treated eyes. Both types of liposomes undergo significant systemic absorption. Since, PEG-lip are more resistant to phagocytosis, they may provide more sustained drug delivery.

Abstract: Lately, nanostructure based biosensor application has drawn a lot attention among fellow researchers because of speciality to detecting cell, tissue and even disease caused by viruses either from humans, animals or agricultures. The nanostructure based biosensoris a result of the changed nature of nanomaterial to draw biomolecules and other biological samples based.In order to do so, formation of nanostructure based biosensor such nanowire must through a couplecritical or important processes such as trimming technique which leading towards formation of nanostructure while surface modification process leading towards by changing material of nanostructure behaviour to become biosensor. All the important process will be elaborated in technique section. Lastly in the result section, form structure produced, structure measurement and its behaviour will be elaborated.

Abstract: Iron-based nanocatalyst was prepared via impregnation method on SiO₂ support. The effects of promoters, namely, K and Cu, on the physical properties and catalytic performance in FTS have been investigated. The FTS performance of the synthesized nanocatalysts was examined in a fixed-bed microreactor at temperature of 523K, atmospheric pressure, 1.5 reactant ratio (H₂/CO) and space velocity of 3L/g-cat.h. In FTS reaction, Cu promoter resulted in a lower CO conversion and C₅₊ hydrocarbons selectivity but higher selectivity to the lighter hydrocarbons (C₁-C₄) compared to those obtained using the K promoter. Higher CO conversion (28.9%) and C₅₊ hydrocarbons selectivity (54.4%) were obtained using K as a promoter compared to that of Cu promoter. However, the K-promoted nanocatalyst resulted in a lower CO conversion but higher selectivity of the heavy hydrocarbons (C₅₊) compared to those obtained using the un-promoted nanocatalyst.

Abstract: Silver nanoparticles are seen as a possible replacement for high temperature solders containing 90-95 wt.% Pb, which is widely used in various applications e.g. automotives. These high temperature solders have been exempted from the Restriction of Hazardous Substances (RoHS) Directive due to very limited drop-in replacement for the high temperature solders. Although the effect of sintering temperature of silver nanoparticles has been studied, the mechanism involved in the changes in the morphology of the particles and interfacial reaction with the substrate as a function of sintering temperature must be understood. In this study the effect of sintering temperature on the morpohology of Ag nanoparticles is discussed. The Scanning Electron Microscopy (SEM) analysis was used to analyze the changes in morphology of silver particles agglomerates with sintering temperatures. Results showed necking of the nanosilver powder, which indicated the occurrence of sintering through grain boundary diffusion process. Meanwhile, the micro-silver powder showed agglomeration of particles but no necking was observed. The study has shown that the Ag agglomerates was observed to undergo various changes to the particle morphology with different sintering temperatures.

Abstract: In the production of polymer nanocomposites, the processing method determines the dispersion of the nanofiller and hence, the final nanocomposite properties. In this work, the potential of high energy milling of the organofluoromica to improve the platelet dispersion and exfoliation in both solvent cast and melt processed thermoplastic polyurethane (TPU)/organofluoromica nanocomposites was investigated. The potential of high energy milling of the organofluoromica to improve the platelet dispersion and exfoliation in both solvent cast and melt processed thermoplastic polyurethane (TPU)/organofluoromica nanocomposites was investigated. The applied high energy milling process has successfully reduced this nanofiller platelet length from 640 nm to 400 nm and 250 nm after 1 hour and 2 hours respectively. These lower aspect ratio milled nanofillers resulted in improved quality of dispersion and delamination when incorporated into the TPU and hence interacted more preferentially with the TPU matrix.

Abstract: Modified Callaway's theory was used to calculate lattice thermal conductivity (LTC) of Germanium nanowires. Results are compared to those of experimental values of the temperature dependence of LTC for nanowire diameters of 62, 19, and 15nm. In this calculation, both longitudinal and transverse modes are taken into account. Scattering of phonons is assumed to be by nanowire boundaries, imperfections, dislocations, electrons, and other phonons via both normal and Umklapp processes. Effect of parameters, phonon confinement and imperfections in limiting thermal conductivity for the nanowires under considerations are investigated. The suppression in thermal conductivity of these nanowires is arise from electron-phonon scattering and phonon-boundary scattering at low temperatures, while at high temperatures is due to imperfections and intrinsic properties.

Abstract: The ability of a cell to adhere and transmit traction forces to a surface reveals the cytoskeleton integrity of a cell. Shear sensitive liquid crystals were discovered with new function in sensing cell traction force recently. This liquid crystal has been previously shown to be non-toxic, linear viscoelastic and sensitive to localized exerted forces. This paper reports the possibility of extending the application of the proposed liquid crystal based cell force sensor in sensing traction forces of osteoblast-like (MG-63) and human keratinocyte (HaCaT) cell lines exerted to the liquid crystal sensor. Incorporated with cell force measurement software, force distributions of both cell types were represented in force maps. For these lowly contractile cells, chondrocytes expressed regular forces (10 – 90 nN, N = 200) around the circular cell body whereas HaCaT projected forces (0 – 200 nN, N = 200) around the perimeter of poly-hedral shaped body. These forces are associated with the organisation of the focal adhesion expressions and stiffness of the LC substrate. From the results, liquid crystal based cell force sensor system is shown to be feasible in detecting forces of both MG63 and HaCaT.

Abstract: Refrigerant-based nanofluids are termed as nanorefrigerants, which are capable of improving the performance of refrigeration systems. Refrigerants act as coolants due to their low boiling temperature. Therefore, the condition of nanoparticles during this phase change needs to be clarified. In this paper the migration properties of nanoparticles during pool boiling of a nanorefrigerant have been experimentally studied. The effects of nanoparticle type, size and weight on the migration of nano-sized particles have been investigated. Al₂O₃ and TiO₂ particles, each with two different average diameters, were used with R141b refrigerant as the base fluid. Experimental results show that migrated mass of nanoparticles increases with the increase of initial mass of nanoparticles and sizes of nanoparticles as well. However, migration of nanoparticles decreases with the increase of the density of nanoparticles. Hence, migration properties of nanoparticles have a notable relationship with the distribution of nano-sized particles.

Abstract: Nickel (Ni) / indium tin oxide (ITO) nanostructures were deposited on silicon (111) substrate by RF magnetron sputtering using a nickel target and metallic alloy target (In-Sn, 90%-10%). The post-deposition annealing has been done for Ni/ITO films in air and the effect of annealing temperature on the surface morphology of ITO films was studied. It has been found that the annealing temperatures increase the film surface roughness in Ni/ITO structure. At annealing temperature of 600°C, AFM analysis reveals the highest root mean square roughness, peak to valley and thickness value of 2.598 nm, 59.115 nm, and 11.358 nm, respectively. Watershed analysis on AFM images show that the numbers of grain boundaries in Ni/ITO are reduced when annealing temperature is increased to higher temperatures.