Advanced Materials Research Vol. 667

Abstract: An effort is made to develop a computer programme using C++ to explain the working of a adjacency linked-list representation of a directed graph or digraph and explain the allocation of data using C++. The program uses the concept of arranging a graph in the form of a linked list for the computer to understand the graphical form representation of any data. The graph algorithms are a significant field of interest within computer science. Typical higher level operations associated with graphs are; finding a path between two nodes, like depth-first search and breadth-first search and finding the shortest path from one node to another, like Dijkstra's algorithm. A solution to finding the shortest path from each node to every other node also exists in the form of the Floyd-Warshall algorithm. A directed graph can be seen as a flow network, where each edge has a capacity and each edge receives a flow. The Ford-Fulkerson algorithm is used to find out the maximum flow from a source to a sink in a graph. Conversion of a graph into a computer storable digital data is useful for nanodevices.

Abstract: Recent research papers for zinc oxide (ZnO) thin films prepared by dip-coating method are reviewed. The aim is on the factors affecting the properties of ZnO thin films prepared by dip-coating method and the preparation of ZnO solution precursor using sol-gel process. Several of journals have been discovered to find out the related study on this topic. It was found that solution chemical equilibrium, substrate and thermal processing are the factors that contribute to the various properties of ZnO thin films. This review hopefully can help in improving the properties of ZnO thin film for possible applications to photoconductor, integrated sensor, transparent conducting oxide electrodes, optoelectronic devices and so on.

Abstract: A novel route to wood modification by impregnation of nanoclay combined with phenol formaldehyde (PF) resin is developed in this study. Wood polymer nanocomposites (WPNCs) were prepared from several tropical wood species by impregnating the woods with PF/nanoclay formulations. The vacuum-pressure method was used to impregnate the samples with PF/nanoclay prepolymer mixture. The formation of wood polymer nanocomposites and the location of impregnated materials inside wood were confirmed through SEM image and XRD pattern respectively. The PF/nanoclay loading achievable was found to be dependent on the properties of wood species. Low loading was observed for the high density wood species. Mechanical strength of fabricated WPNCs in terms of modulus of elasticity (MOE) was found to be significantly improved. Furthermore, morphological properties of raw wood and WPNC samples were evaluated by scanning electron microscopy (SEM) and XRD analysis and a change in morphological properties was also observed for WPNC.

Abstract: In this study, the ZnO/TiO2 nanocomposite thin films were prepared by RF Magnetron co-sputtering ZnO and TiO2 targets at different deposition times from 30-75 minutes. The electrical and structural properties ZnO/TiO2 nanocomposite thin films were characterized by I-V measurement, atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM). The electrical characteristics of nanocomposite films revealed that the conductivity of thin films increases as the thickness increase due to the improvement in surface contact between particles as well as photocatalytic activity. High conductivity at 1.67x10-4 S/cm and lowest resistivity about 5.14x104 Ω/cm were obtained for 75 minutes deposition time. Atomic force microscopy (AFM) showed particle size of ZnO/TiO2 thin films varied from 27nm to 51nm with an increasing in deposition time with granular shapes structures were observed from field emission scanning electron microscopy (FE-SEM).

Abstract: The aim of this study is to engage a basic understanding of the information carbon nanotubes (CNTs) may yield when this CNTs is deposited on silicon substrate over ferrocene and aluminum isopropoxide catalyst. Several popular methods are used to produce high quality CNT such as chemical vapour deposition, arc discharge and others. Most promising method is, chemical vapour deposition (CVD), used to produce CNTs in this experiment. The carbon source and catalyst were placed at different alumina boat in furnace one (1). The silicon substrate was placed at the deposition furnace and range temperature from 700 oC to 900 oC. The G-band peaks of the CNTs appear at round 1580 cm-1 and D-band peaks appear at 1348 cm-1. Thermal analyses show the percentage of CNTs weight loss 75.12%, 86.39%, 86.54%, 87% and 92.3% respectively. FESEM images was observed to study the formation of the CNTs. The CNTs were successfully synthesized from the chemical vapour deposition method.

Abstract: This paper will report on the synthesis of bundles of aligned single wall carbon nanotubes (SWCNTs) and multiwall carbon nanotubes (MWCNTs) from palm oil precursor and ferrocene as catalyst source by two stage aerosol-assisted CVD system at various deposition temperature ranging from 700-900oC. Palm oil was pyrolised into the furnace which contained the catalyst source producing black substances at the wall of the reaction furnace which were then collected to be characterized. Field emission scanning electron microscopy equipped with energy dispersive X-ray was used to obtain weight percentage, identification of samples and image of CNTs which showed different structures and diameters of CNTs relative to the deposition temperature of furnace. Raman Spectroscopy was used to further study the quality and identification of samples and finally X-ray powder diffraction was used to determine the crystalinity of samples. Individual micrograph of MWNTs at optimized deposition temperature was also obtained from the high resolution transmission electron microscopy.

Abstract: InxGa1-xAs NWs have been grown with various indium mole fractions (x) using MOCVD. The morphology of InxGa1-xAs NWs was observed using Field Emission-Scanning Electron Microscopy (FE-SEM) in order to study the growth behavior of the NWs. FE-SEM results show that the NWs growth mechanism has changed due to changing of indium mole fraction. At low indium mole fraction, the NWs grew via direct impinging mechanism which has produced NWs with relatively uniform diameter. By increasing the value of x the growth mechanism has transformed to the combination of direct impinging and diffusion of source atoms from the surface of substrate causing tapering of NWs. The degree of tapering increases with increasing value of indium mole fraction. InxGa1-xAs NW grown at x = 0.65 has the highest tapering factor, TF = 12.82, whereas NW grown at x = 0.41 has the lowest tapering factor, TF = 2.76.

Abstract: β-SiC nanowires were successfully fabricated on pare Si (100) substrate using simple carbo-thermal evaporation of graphite at 1200°C. The obtained β-SiC nanowires were aligned with diameters ranged between 40 to 500 nm. The majority of crystal planes were β-SiC (111) with other less intensity of (200), (220) and (311). The silicon substrate location inside the furnace found to be critical in the formation of the β-SiC nanowires. Also, FTIR absorption peaks for β-SiC nanowires found at higher frequency side of 1110 cm-1 which is pointed to Si–O asymmetric stretching mode.

Abstract: This paper presents cellulose acetate (CA) - ammonium tetrafluoroborate (NH4BF4) salt complexes films via solution cast technique. The relationship between ionic conduction and the glass transition temperature was investigated in selected cellulose-salt complexes via electrical impedance spectroscopy (EIS) and differential scanning calorimetry (DSC). The thermal study of the films has also investigated using thermogravimetric analysis (TGA).

Abstract: Centella asiatica (C. Asiatica) is a traditional herb that has been used in raditional medicine especially in Asia region. Recently the pharmalogical study of Asiatic acid (AA) which is one of bioactive constituents in C. Asiatica has been studied and revealed that this compound has a potential to be use in medicine area. The objective of this paper is to produce nanoparticles C. Asiatica by Planetary Ball Mill (PBM) and determined the effect of nanonization on extraction yield of asiatic acid. The particles were analyzed using particle sizer to determine size of particle produce and the morphology was evaluated through FESEM. As a result, the mean particles size of nanopowders was 501.10 nm and the extraction of asiatic acid using nanopowders showed 82.09 % higher than original powder.