Papers by Author: Saadah Abdul Rahman

Abstract: Hardwood is from angiosperm trees. The characteristic of woods include flower, endosperm within seeds and the production of fruits that contain the seeds. This paper aim is to discuss the preparation and characterization the cellulose obtained from hardwood and the analysis of the cellulose from x-ray diffraction result. The hardwood Merbau (Intsia bijuga) was chosen as raw material in this study. Ethanol toluene, lignin and holocellulose extraction methods were used for the preparation of cellulose while acid hydrolysis was used to produce the cellulose nanocrystal (CNC). The untreated (pure hardwood Merbau) and cellulose samples were characterized using XRD. The final products from all samples were then compared.

Abstract: Hardwood is wood from angiosperm trees. The characteristic of hardwood include flowers, endosperm within seeds and the production of fruits that contain the seeds. This paper aims to discuss the preparation and characterization of cellulose obtained from hardwood. The hardwood Merbau (Intsia bijuga) was chosen as raw material in this study. Alkaline treatment and delignification methods were used for the preparation of cellulose. Acid hydrolysis was employed to produce cellulose nanocrystal (CNC). The treated and untreated samples were characterized using x-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The final product, from both trated and untreated samples were then compared.

Abstract: We utilized Deoxyribonucleic acid (DNA) strands immobilized between a metal gap and its behavior was investigated. The DNA strands were initially prepared using the PCR method while gaps of 10.00 μm lengths were created on gold layer deposited onto silicon substrate. Once immobilized, current-voltage characterization was carried out on the Au-DNA-Au structure fabricated under the presence and absence of magnetic field. Experimental results clearly highlight the behavior of the DNA strands similar to semiconductor materials. An exponential decrease observed in the current in presence of external magnetic field suggests possible future application as a magnetic sensor.

Abstract: Hydrogenated nanocrystalline silicon (nc-Si:H) films produced by layer-by-layer (LBL) deposition technique were studied. The films were grown at different hydrogen to silane flow-rate ratio on crystal silicon (111) substrate. The properties of films were investigated by X-ray diffraction (XRD), micro-Raman scattering spectroscopy, Fourier transform infrared (FTIR) spectroscopy, optical transmission spectroscopy, atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). These properties showed dependence on the hydrogen dilution of silane. Appearance of XRD peaks at diffraction angles of 28.4 o and 56.1 o which correspond to silicon orientation of (111) and (311) respectively, were observed in all films indicating evidence of crystallinity in the films. Raman scattering results indicated that crystallinity in the films was due to the presence of nanocrystallites embedded in an amorphous matrix. The energy gap of the films showed dependence on the hydrogen content in the films. Increase in nanocrystallite size resulted in increase in disorder at low hydrogen dilution films but films remain homogenous with increase in nanocrystallite size for the high hydrogen dilution films.

Abstract: A direct-current plasma enhanced chemical vapour deposition (PECVD) system was designed and built in-house for the deposition of hydrogenated amorphous carbon(a-C:H) thin films. In this work, a-C:H thin films prepared using this system at different deposition pressures were studied. The influence of deposition pressure on the deposition rate, energy gap, bonded hydrogen content and structure of the film has been investigated. The characterization techniques were determined from optical transmission spectroscopy, Fourier transform infrared spectroscopy and Xray diffraction measurements. The results demonstrated that the deposition pressure had strong influence on the deposition rate, optical energy gap and the bonded H content in the film. Evidence of crystallinity was observed in films prepared at low deposition pressure.