George Town, Malaysia
George Town, Malaysia

Time filter

Source Type

Jahani S.,UniversitiSains Malaysia | Samsudin A.,UniversitiSains Malaysia
Applied Mechanics and Materials | Year: 2013

The number theory based cryptography algorithms are the most commonly used publickeycryptosystems. One of the fundamental arithmetic operations for such systems is the large integer multiplication. The efficiency of these cryptosystems is directly related to the efficiency of this large integer multiplication operation. Classical multiplication algorithm and Karatsubamultiplication algorithm, and their hybrid,are among the most popular multiplication algorithms used for this purpose. In this paper, we propose a hybrid of Karatsuba and a classicalbased multiplication algorithm, enhanced by a new number representation system. The new number representation, known as "Big-Digits",is used to carry out the sub-multiplication operation in the new multiplication algorithm. Big-Digits has a compact representation with lower Hamming weight. As the result, the number of sub-multiplication operations for the multiplication algorithm that is based on the Big-Digits representation is significantly reduced. Our results show that the proposed multiplication algorithmis significantly faster than the classical, Karasuba and the hybrid of Karatsuba-Classical multiplication algorithms within the implementation domain of the publickey cryptography. © (2013) Trans Tech Publications, Switzerland.

Chang B.P.,UniversitiSains Malaysia | Akil H.M.,UniversitiSains Malaysia | Nasir R.M.,UniversitiSains Malaysia
Procedia Engineering | Year: 2013

Ultra-high molecular weight polyethylene (UHMWPE) reinforced with different loadings of zeolite particles were prepared using hot compression molding. The effects of zeolite particles on the mechanical and tribological properties of the UHMWPE composites were studied. The tribological properties were investigated using a Ducom TR-20 pin-on-disc tester under different sliding speeds of 0.209 m/s, 0.419 m/s and 0.838 m/s with various applied loads of 10, 20, and 30 N. The worn surfaces and transfer films of the zeolite/UHMWPE composites were observed under the scanning electron microscope (SEM). The results showed that the addition of zeolite into UHMWPE matrix has reduced the tensile strength and elongation at break, but increased the modulus. The 10 wt.% zeolite/UHMWPE composites showed an increase of ∼25% in impact strength as compared to pure UHMWPE. The 20 wt.% zeolite/UHMWPE composite exhibited lowest wear volume loss as compared to 10 wt.% zeolite/UHMWPE and pure UHMWPE. In addition, the average coefficient of friction (COF) was also found to decrease with the addition of zeolite. The lowest average COF was also obtained with the 20 wt.% zeolite/UHMWPE composite. The wear volume loss was found to increase with increasing applied loads for all samples. Meanwhile, the average COF values have decreased with increasing applied loads. Furthermore, shallower wear grooves and smoother worn surfaces were observed for zeolite/UHMWPE composites as compared to pure UHMWPE. In terms of the transfer film observation, the counterface of pure UHMWPE were partially covered, rough, and discontinuous. On the other hand, counterface of zeolite/UHMWPE composites were fully covered, smooth, and continuous. Overall, the tribological properties showed significant improvement with the reinforcement of zeolite in UHMWPE. © 2013 The Authors. Published by Elsevier.

Nabihah M.F.,UniversitiSains Malaysia | Shanmugan S.,UniversitiSains Malaysia
Digest Journal of Nanomaterials and Biostructures | Year: 2016

Beryllium oxide (BeO) nanoparticles were synthesized by polyacrylamide gel route followed by calcination at 700°C and 800° C and examined their structural behaviour by X-ray diffraction (XRD). The structural parameters such as dislocation density, residual stress, lattice strain, texture coefficient, lattice parameter and bond length were calculated from XRD data and discussed. The calculated crystallite size was in nanometer scale (<70 nm) and reduced when calcined at 800°C. Dislocation density was changed with respect to orientations and observed low value for (100) orientated phase when calcined at 700°C. Residual stress analysis evidenced the formation of compressive stress and dominated for calcined BeO nanoparticles. Calcination temperature did not much influence in changing the Be-O bond length. The synthesis of preferentially (002) oriented BeO nanoparticles were confirmed by texture coefficient analysis. Transmission Electron Microscopy (TEM) was attested the formation of nano particles with ellipsoid-like shape and agreed with XRD results. Stoichiometric BeO nano particles were confirmed by EDX spectra. © 2016, Inst Materials Physics. All right reserved.

Jaafar H.,UniversitiSains Malaysia | Sharif S.E.T.,UniversitiSains Malaysia | Murtey M.D.,UniversitiSains Malaysia
Tumori | Year: 2014

Aims and background. Parenchymal cells naturally interact, react and adapt with the environment including stromal components around them in order to maintain tissue architecture and function. However, studies have shown that this spontaneous interaction will become crucial in assisting cancer invasion. The purpose of the study was to analyze the pattern of collagen deposition and localization of matrix metalloproteinase 2 and matrix metalloproteinase 9 in the tumor microenvironment during breast cancer invasion. Methods and study design. A standard transmission electron microscopy procedure was used together with the immunogold technique with a few modifications. Results. The ultrastructure of fibroblasts in the vicinity of cancer cells was thick, elongated and spindle shaped with nuclear indentations. Desmoplasia was present near the cancer cells. Collagen fibers were still arranged parallel to the cancer cells and fibroblasts but were less dense than collagen fibers far from cancer cells and fibroblasts. Collagen fibers were less dense in the pericellular region because of proteolytic enzyme activity, which facilitates the invasion of breast cancer cells. In immunogold localization analysis, matrix metalloproteinase 9 had consistent localization throughout cancer cells, fibroblast and stroma. In matrix metalloproteinase 2 localization, gold conjugates were more heavily deposited in cancer cells and fibroblasts than in the stroma. Conclusions. Invasive breast carcinoma is not an independent entity, and its survival depends on the surrounding microenvironment.

Andas J.,University Technology of MARA | Adam F.,UniversitiSains Malaysia
Materials Today: Proceedings | Year: 2016

In this study, silver nanoparticles (AgNP/SiO2) with an average diameter of 25 nm were successfully fabricated using silica rice husk as support via a simple yet cheap sol-gel route at room temperature. The synthesized AgNP/SiO2 was characterized by several spectroscopic methods such as FTIR, SEM/EDX, XRD, N2 adsorption-desorption and TEM analyses. FTIR and EDX analyses showed the successful inclusion of silver into the silica framework. Preservation of the amorphous nature of silica in AgNP/SiO2 was confirmed from the high angle powder XRD analysis. High mesoporosity of AgNP/SiO2 (BET surface area = 514 m2g-1 and pore volume = 0.50 ccg-1) was clearly evidenced from the N2-sorption studies. Well-dispersion of spherical Ag nanoparticles was observed through the TEM investigation. This research proves the successful conversion of uneconomical biomass into discreet AgNP/SiO2 via a facile and novel sol-gel method. © 2016 Elsevier Ltd.

Ahmad N.,UniversitiSains Malaysia
Materials Science Forum | Year: 2015

he influence of alginate concentration on the diametral tensile strength (DTS) of hydroxyapatite (HAp) block was investigated. Alginate solution with concentration of 1%, 3% and 5% was prepared through neutral extraction from cultivated sargassum polycystum brown seaweed obtained from Semporna, Sabah, Malaysia. Commercially available HAp powder was pressed uniaxially at 3 MPa to obtain the HAp block. The HAp block was then sintered at 900°C. The sintered HAp block was then immersed in alginate solution under vacuum condition for 24 hours. DTS value of the HAp block decreases with increasing alginate concentration. Porosity measurement increases with the increase in alginate concentration used. The decrease in the DTSvalue with increasing alginate concentration is due to the higher viscosity at higher alginate concentration and thus limited the amount of alginate being penetrate into the HAp block. © (2015) Trans Tech Publications, Switzerland.

Lew L.-C.,UniversitiSains Malaysia | Liong M.-T.,UniversitiSains Malaysia | Gan C.-Y.,UniversitiSains Malaysia
Journal of Applied Microbiology | Year: 2013

Aims: The study aimed to optimize the growth and evaluate the production of putative dermal bioactives from Lactobacillus rhamnosus FTDC 8313 using response surface methodology, in the presence of divalent metal ions, namely manganese and magnesium. Methods and Results: A central composite design matrix (alpha value of ±1·414) was generated with two independent factors, namely manganese sulphate (MnSO4) and magnesium sulphate (MgSO4). The second-order regression model indicated that the quadratic model was significant (P < 0·01), suggesting that the model accurately represented the data in the experimental region. Three-dimensional response surfaces predicted an optimum point with maximum growth of 10·59 log10 CFU ml-1. The combination that produced the optimum point was 0·80 mg ml-1 MnSO4 and 1·09 mg ml-1 MgSO4. A validation experiment was performed, and data obtained showed a deviation of 0·30% from the predicted value, ascertaining the predictions and the reliability of the regression model used. Effects of divalent metal ions on the production of putative dermal bioactives, namely hyaluronic acid, diacetyl, peptidoglycan, lipoteichoic acid and organic acids in the region of optimized growth, were evaluated using 3D response surfaces generated. Evaluation based on the individual and interaction effects showed that both manganese and magnesium played an important role in the production of these putative bioactives. Conclusions: Optimum growth of Lact. rhamnosus FTDC 8313 in reconstituted skimmed milk was achieved at 10·59 log10 CFU ml-1 in the presence of MnSO4 (0·80 mg ml-1) and MgSO4 (1·09 mg ml-1). Production of putative dermal bioactive and inhibitory compounds including hyaluronic acid, diacetyl, peptidoglycan, lipoteichoic acid and organic acids at the regions of optimized growth showed potential dermal applications. Significant and Impact of the Study: This research can serve as a fundamental study to further evaluate the potential of Lactobacillus strains in non-gut-related roles such as dermal applications. © 2012 The Society for Applied Microbiology.

Muniandy K.,UniversitiSains Malaysia | Ismail H.,UniversitiSains Malaysia | Othman N.,UniversitiSains Malaysia
BioResources | Year: 2012

The effects of partial replacement of rattan powder (RP) by carbon black (CB), mica, and calcium carbonate (CaCO3) on the curing characteristics, tensile properties, rubber-filler interaction, and morphological studies of natural rubber (NR) composites were investigated. Rattan powder with an average particle size of less than 180 μm was used in this study. NR/RP/CB, NR/RP/mica, and NR/RP/CaCO3 composites with five different RP/commercial fillers loadings (i.e. 30/0, 20/10, 15/15, 10/20, 0/30 phr) were prepared using a laboratory size two-roll mill. Results showed that the maximum torque (MH) of the NR/RP/CB, NR/RP/mica, and NR/RP/CaCO3 composites increased with increasing the commercial filler-loading ratio. The scorch time (ts2) and cure time (t90) of NR/RP/CB composites decreased as the ratio of CB loading was increased, whereas, ts2 and t90 of NR/RP/mica and NR/RP/CaCO3 composites increased as mica and CaCO3 loading ratio were raised, respectively. The tensile strength, elongation at break (Eb), stress at 100% elongation (M100), and stress at 300% elongation (M300) of all the composites increased as the commercial filler-loading ratio increased. This is due to the presence of the commercial filler, which brought a better rubber-filler interaction, as confirmed by the rubber-filler interaction and scanning electron microscopy (SEM) studies.

Muniandy K.,UniversitiSains Malaysia | Ismail H.,UniversitiSains Malaysia | Othman N.,UniversitiSains Malaysia
BioResources | Year: 2012

This article investigates the effect of natural weathering on mechanical and morphological properties of rattan powder-filled natural rubber (NR) composites as a function of filler loading and silane coupling agent. The rattan powder samples in the range of 0 to 30 phr were compounded with NR using a laboratory size two-roll mill. The natural weathering test was carried out for six months. The degradation of the samples was evaluated by performing a tensile test, a Fourier transform infrared spectroscopy (FTIR), and a scanning electron microscopy (SEM) test. The results indicated that after natural weathering, an increase in stress at 100% elongation (M100) can be seen for samples without the silane coupling agent, whilst M100 was reduced for samples with silane coupling agent. A drastic reduction in tensile strength and elongation at break were observed for all samples due to the photo-oxidation process that occurred during the degradation of the samples. The extent of degradation on the samples' surfaces and the presence of oxygenated products were confirmed by SEM and FTIR studies, respectively.

Damavandinejadmonfared S.,UniversitiSains Malaysia
Proceedings - 2012 IEEE 8th International Conference on Intelligent Computer Communication and Processing, ICCP 2012 | Year: 2012

In this paper, a new method for face recognition in video surveillance is proposed. Local mean-based k-nearest centroid neighbour (LMKNCN) is a recently proposed method for classifying data which has been proven to be more appropriate than other classifiers such as k-nearest neighbour (KNN), K-Nearest Centroid Neighbour (KNCN), and local mean-based k-nearest neighbour (LMKNN). Kernel Entropy Component Analysis is a new extension of 1-D PCA-based feature extractions methods enhancing the performance of PCA-based methods. In the proposed method in this paper, LMKNCN is used as a classifier in KPCA method. Moreover, the Extensive experiments on surveillance camera faces database (SCfaces) and Head Pose Image database reveal the significance of the proposed method. © 2012 IEEE.

Loading UniversitiSains Malaysia collaborators
Loading UniversitiSains Malaysia collaborators