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Almaslow A.,National University of Malaysia | Ghazali M.J.,National University of Malaysia | Talib R.J.,Advanced Materials Research Center | Ratnam C.T.,Malaysian Nuclear Agency | Azhari C.H.,National University of Malaysia
Wear | Year: 2013

A group of semi-metallic friction composites (SMFC) consisting of epoxidized natural rubber-alumina nanoparticles (ENRAN), steel wool, graphite, and benzoxazine were prepared using a melt mixing method. The mixing work was carried out at 90°C. The composites were vulcanized by electron beam irradiation. The samples were then subjected to mechanical and physical tests to determine the tribological properties of SMFC. Detailed examinations on the worked layer were analyzed using a scanning electron microscopy with an energy dispersive X-ray. Samples with 29% of ENRAN exhibited the best friction coefficient (~0.437) with low specific wear rates (0.27×10-7cm3/Nm). An iron oxide formation was prominent on the friction surfaces, implying the occurrence of interactions between the contacting surfaces and the environment. © 2013 Elsevier B.V.


Periayah M.H.,Universiti Sains Malaysia | Halim A.S.,Universiti Sains Malaysia | Hussein A.R.,Universiti Sains Malaysia | Mat Saad A.Z.,Universiti Sains Malaysia | And 2 more authors.
International Journal of Biological Macromolecules | Year: 2013

Chitosan-derived hemostatic agents with various formulations may have distinct potential in hemostasis. This study assessed the ability of different grades and forms of chitosan derivatives as hemostatic agents to enhance platelet adhesion and aggregation in vitro. The chitosan derivatives utilized were 2% NO-CMC, 7% NO-CMC (with 0.45. mL collagen), 8% NO-CMC, O-C 52, 5% O-CMC-47, NO-CMC-35, and O-C 53. Samples of chitosan derivatives weighing 5. mg were incubated at 37. °C with 50. μL of phosphate buffer saline (PBS) (pH 7.4) for 60. min. The morphological features of the platelets upon adherence to the chitosan were viewed using scanning electron microscope (SEM), and the platelet count was analyzed with an Automated Hematology Analyzer. For platelet aggregation, we added an adenosine diphosphate (ADP) agonist to induce the chitosan-adhered platelets. O-C 52 bound with platelets exhibited platelet aggregates and clumps on the surface of the membrane layer with approximately 70-80% coverage. A statistically significant correlation (p< 0.01) for the platelet count was identified between the baseline value and the values at 10. min and 20. min. The results indicate that O-C 53 and O-C 52 were able to promote clotting have the potential to induce the release of platelets engaged in the process of hemostasis. © 2012 Elsevier B.V.


Jamuna-Thevi K.,Advanced Materials Research Center | Bakar S.A.,Advanced Materials Research Center | Ibrahim S.,Advanced Materials Research Center | Shahab N.,SIRIM Berhad | Toff M.R.M.,Advanced Materials Research Center
Vacuum | Year: 2011

Surface treatments on biomaterials using several methods have greatly reduced the in vivo bacterial attachment, surface colonization and formation of biofilm. In this study, the effect of silver (Ag) ion release against in vitro antibacterial activity and cytotoxicity of 1-4wt% Ag doped titania (TiO 2) thin film coatings were evaluated. These coatings were deposited for 1-6 h onto stainless steel substrate (SS) using (radio frequency) RF magnetron sputtering technique. The coatings predominantly in the crystalline anatase phase were configured using X-ray Diffraction (XRD). Scanning electron microscopy (SEM) observation showed the presence of Ag-TiO2 nanoparticles of less than 100 nm in all the coated surfaces confirming the formation of nanostructured coatings. An initial rapid release, followed by a sustained lower release of Ag ion concentration was measured between 0.45 and 122 ppb when all the coated substrates immersed in Phosphate Buffered Saline (PBS) for 1-10 days. The obtained concentration was less than the maximum toxic concentration for human cells; yet achieved antibacterial concentration, sufficient to kill or inhibit the growth of bacteria. In vitro cytotoxicity results have indicated that 1-4 wt% of Ag doped TiO2 coatings had no adverse effect on mouse fibroblast proliferation, confirming its cytocompatibility. The antibacterial assessment was performed on 1 and 2 wt% Ag-TiO2 coatings using Staphylococcus aureus (S. aureus) whereby significant antibacterial activity was observed in 2 wt% Ag-TiO2 coatings. © 2011 Elsevier Ltd. All rights reserved.


Mahammad Rafter M.F.,University Tun Hussein Onn Malaysia | Ahmad S.,University Tun Hussein Onn Malaysia | Ibrahim R.,Advanced Materials Research Center
Materials Science Forum | Year: 2016

Nowadays, the 316L stainless steel metal foams (SS316L) have acknowledged important attention in various fields and are required to be used as engineering materials including heat exchange, sound absorption, filtration and others. So, in this study the production of SS316L foams using different composition through compaction method by using a starch powder as space holder was studied. The range of selected composition of SS316L that obtained is between 50 wt.% to 60 wt.% while the remaining percentages are space holder and binder. The SS316L compact is prepared by mixing SS316L alloy powder, starch powder, and Polyethylene Glycol (PEG). Then, the mixture is compact into a mould under 8 tonnes of controlled pressure using hydraulic press machine. This is later sintered in a vacuum furnace. The sintered SS316L foams were characterized using a Scanning Electron Microscopy (SEM) analysis. Then, the physical properties of SS316L foam was also analysed by Archimedes method that includes porosity and bulk density test. As a result, the sample with 60 wt.% were produced a good and finer pores and struts. Meanwhile, for that sample the percentage of porosity and bulk density are 0.19% and 7.44 g/cm3, respectively. © 2016 Trans Tech Publications, Switzerland.


Kiamahalleh M.V.,Universiti Sains Malaysia | Zein S.H.S.,Universiti Sains Malaysia | Najafpour G.,Babol Noshirvani University of Technology | Sata S.A.,Universiti Sains Malaysia | Buniran S.,Advanced Materials Research Center
Nano | Year: 2012

Electrode materials are the most important factors to verify the properties of the electrochemical supercapacitor. In this paper, the storage principles and characteristics of electrode materials, including carbon-based materials, transition metal oxides and conducting polymers for supercapacitors are depicted in detail. Other factors such as electrode separator and electrolyte are briefly investigated. Recently, several works are conducted on application of multiwalled carbon nanotubes (MWCNTs) and MWCNTs-based electrode materials for supercapacitors. MWCNTs serve in experimental supercapacitor electrode materials result in specific capacitance (SC) value as high as 135 Fg -1. Addition of pseudocapacitive materials such as transition metal oxides and conducting polymers in the MWCNTs results in electrochemical performance improvement (higher capacitance and conductivity). The nanocomposites of MWCNTs and pseudocapacitive materials are the most promising electrode materials for supercapacitors because of their good electrical conductivity, low cost and high mass density. © 2012 World Scientific Publishing Company.


Jamuna-Thevi K.,Advanced Materials Research Center | Jamuna-Thevi K.,University of Technology Malaysia | Daud N.M.,University of Technology Malaysia | Abdul Kadir M.R.,University of Technology Malaysia | Hermawan H.,University of Technology Malaysia
Ceramics International | Year: 2014

The synthesis of multiple ions doped nanoapatite powder was carried out by wet precipitation technique. A newly developed reaction route with self-controlled pH at high reaction temperatures, i.e. 37 & 85±2 C was compared to the conventional synthesis route at 37±2 C. The XRD peaks were very broad, indicating the presence of nanocrystalline apatite. The primary particle size of the powder was in the range of 20-30 nm whereas the fraction of crystallinity was between 0.20 and 0.63. TEM and SEM characterizations confirmed the nanosized primary particles of the apatite samples. The high temperature synthesis at 37 & 85±2 C improved both crystallite size and crystallinity of the as-prepared samples. A highly crystalline HA phase was formed in the ions doped samples without secondary phases, indicating its thermal stability at 900 C in both CO2 and air atmosphere. The in vitro cytocompatibility of the synthesised nanoapatite powders was confirmed by cell viability of human skin fibroblasts. © 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.


Raza M.R.,Petronas University of Technology | Ahmad F.,Petronas University of Technology | Omar M.A.,Advanced Materials Research Center | German R.M.,San Diego State University
Journal of Materials Processing Technology | Year: 2012

This study presents the results of corrosion behavior of powder injection molded 316L stainless steel parts sintered in vacuum. The feedstocks of metal powder and plastic binder were prepared and their viscosity was measured. Green samples were injection molded and binder was removed from the green parts. Brown test parts were sintered at 1325 °C with heating rate of 5 °C/min and 10 °C/min for 2 h followed by the same cooling rate. Corrosion response of the sintered test samples was measured by weight loss method in Ringer's Solution of pH 7.4 for 15 days. The test samples using cooling rate 10 °C/min showed higher mechanical properties and improved corrosion resistance compared to those sintered at low heating and cooling rate. High cooling rate reduced the evaporation of Cr and developed passive chromium oxide layer on the test samples resulting improved corrosion resistance. © 2011 Elsevier B.V. All rights reserved.


Jamuna-Thevi K.,Advanced Materials Research Center | Suleiman M.J.,Advanced Materials Research Center | Sabri S.N.,Advanced Materials Research Center
Materials Today: Proceedings | Year: 2016

Fabrication of 3-layered composite membranes comprising of poly(lactic-co-glycolic) acid (PLGA)/nanoapatite (NAp)/lauric acid (LA)using thermally induced phase separation (TIPS) technique showed a significant increase in tensile strength from 1.54 to 2.27 MPawhen TIPS freezing temperature reduced from -18 to-25 °C, respectively. Moreover, an increase in PLGA content at 20wt% in all layers of the membrane composition has increased the tensile strength to 2.45 MPa at -25 °C. A potential guided bone regeneration (GBR) barrier membrane with improved space-making properties (balanced stiffness and elasticity) is obtained by the utilization of TIPS technique and graded membrane compositions for orthopaedic applications. © 2016 The Authors.


Ali M.,COMSATS Institute of Information Technology | Hamzah E.,University of Technology Malaysia | Qazi I.A.,National University of Sciences and Technology | Toff M.R.M.,Advanced Materials Research Center
Current Applied Physics | Year: 2010

Titanium nitride which is widely used as a hard coating material was coated on tool steel, by physical vapor deposition method. Surface roughness was investigated as a function of deposition rate, substrate bias and temperature, nitrogen flow rate and metal ion etching. The study showed that increase in surface roughness mainly depends on the condition of sample preparation, surface treatment, macro-droplets, pitting defects, rise in compressive stress at higher coating thickness, growth defects and to a lesser extent selection of surface under testing. It was observed that chromium ion etching significantly reduced the surface roughness compared to titanium ion etching. © 2009 Elsevier B.V. All rights reserved.


PubMed | Advanced Materials Research Center
Type: Journal Article | Journal: Saudi journal of biological sciences | Year: 2016

Surface reactivity of bioactive ceramics contributes in accelerating bone healing by anchoring osteoblast cells and the connection of the surrounding bone tissues. The presence of silicon (Si) in many biocompatible and bioactive materials has been shown to improve osteoblast cell adhesion, proliferation and bone regeneration due to its role in the mineralisation process around implants. In this study, the effects of Si-biphasic calcium phosphate (Si-BCP) on bioactivity and adhesion of human osteoblast (hFOB) as an in vitro model have been investigated. Si-BCP was synthesised using calcium hydroxide (Ca(OH)2) and phosphoric acid (H3PO4) via wet synthesis technique at Ca/P ratio 1.60 of material precursors. SiO2 at 3wt% based on total precursors was added into apatite slurry before proceeding with the spray drying process. Apatite powder derived from the spray drying process was pressed into discs with 10mm. Finally, the discs were sintered at atmospheric condition to obtain biphasic hydroxyapatite (HA) and tricalcium phosphate (TCP) peaks simultaneously and examined by XRD, AFM and SEM for its bioactivity evaluation. In vitro cell viability of L929 fibroblast and adhesion of hFOB cell were investigated via AlamarBlue (AB) assay and SEM respectively. All results were compared with BCP without Si substitution. Results showed that the presence of Si affected the materials surface and morphology, cell proliferation and cell adhesion. AFM and SEM of Si-BCP revealed a rougher surface compared to BCP. Bioactivity in simulated body fluid (SBF) was characterised by pH, weight gain and apatite mineralisation on the sample surface whereby the changes in surface morphology were evaluated using SEM. Immersion in SBF up to 21days indicated significant changes in pH, weight gain and apatite formation. Cell viability has demonstrated no cytotoxic effect and denoted that Si-BCP promoted good initial cell adhesion and proliferation. These results suggest that Si-BCPs surface roughness (164nm) was significantly higher than BCP (88nm), thus enhancing the adhesion and proliferation of the osteoblast.

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