bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Metal Catalyst Morphology on the Growth of Zinc Oxide Nanostructure by Thermal Vapor Deposition Method
Authors: Rosli Aimi Bazilah , Patah N.D.H.Abd , Shariffudin Shafinaz , Herman S.H. , Rusop Mahmood Mohamad
Published: April 2014

This paper reports on the effects of gold (Au) catalyst on the growth of zinc oxide (ZnO) nanostructures by thermal chemical vapor deposition (TCVD). The thickness of Au catalyst was varied from 5 to 15 nm. The Au catalyst was annealed at 500 °C prior to the deposition of ZnO nanostructures by thermal chemical vapor deposition (TCVD). The morphology of the Au catalyst at different thickness and also ZnO nanostructures were characterized by field emission scanning electron microscopy (FESEM). The material component and crystalline properties of ZnO nanostructures were determined using Energy Dispersive X-ray spectroscopy (EDX) and also Raman Spectroscopy respectively. We found that the shape of the deposited ZnO nanostructures were different on different thickness of Au catalyst. There was no growth of ZnO on the 5 nm thick Au observed by FESEM and supported by EDX due to very small amount of Zn. On the 10 and 15 nm thick Au, growth of ZnO nanostructures were clearly observed.
Adsorption of Aniline Using Novel Mesoporous Carbon Nitride
Authors: Sam Mei Shie , Lintang Hendrik O. , Sanagi Mohd Marsin , Lee Siew Ling , Yuliati Leny
Published: April 2014

Aniline is a toxic organic pollutant that is abundantly present in the environment. One of approaches to remove the aniline is by adsorption process. In this study, mesoporous carbon nitride (MCN) was proposed for the first time to be a potential adsorbent for aniline. The adsorption studies were carried out at room temperature on the aniline solution with various initial concentrations for both bulk carbon nitride (BCN) and MCN. Owing to its larger surface area, the MCN showed much higher adsorption capacity towards aniline compared to the BCN. This result indicated that adsorbent with large surface area is very crucial in the adsorption of aniline. Comparison study was also carried out using mesoporous silica, MCM-41, which was reported to act as a good adsorbent for aniline. The adsorption capability of MCN was found to be higher than that of MCM-41. It was suggested that the MCN with larger pore diameter might have more suitable and favourable adsorption sites for aniline compared to MCM-41. This study obviously showed that MCN would be a new potential adsorbent for removal of aniline.
Structural Properties of Zinc Doped Nanocrystalline Ceria
Authors: Suriakala P. , Tamilarasan K.
Published: April 2014

Zinc doped nanoceria powders were prepared by a simple and fast microwave induced combustion method using cerium nitrate, zinc nitrate, glycine and sorbitol. The resultant powders were examined for their structure and microstructure by XRD, SEM, TEM and their optical properties were measured by UV-Vis spectroscopy. The lattice parameter of the ceria powders was found in the range of 5.399 Å to 5.370 Å. The average crystallite size calculated from XRD was in the range ~ 4 nm to ~ 2.5 nm. The TEM selected area diffraction pattern images clearly showed the ring pattern indicated the powders were polycrystalline nature and there is agglomeration of the particles. Optical band gaps of the powders were in the range 2.71eV to 2.58eV.
Micro-Structural Studies of Thermosonic Cu-Al Bonding Interface
Authors: Anand T. Joseph Sahaya , Kok Yau Chua , Jalar A.
Published: April 2014

Thermosonic Copper (Cu) wire interconnection has been under an extensive research and development to replace expensive Gold (Au) wire material in the semiconductor industry. However, a reliability concern is raised due to void formation at the bonding interface of Copper wire-Aluminum bond pad (Cu-Al) after High Temperature Storage (HTS) annealing condition. It is believed that the Intermetallic Compound (IMC) layer growth and evolution lead to a volumetric shrinkage which in turn results in the void formation. Annealing conditions influence the development of the IMC at the bonding interface which is related to the bonding reliability. In this work, the effects of annealing toward the micro-structure and IMC growth at the bonding interface were evaluated using Scanning Transmission Electron Microscope equipped with Energy Dispersive X-ray analysis. In the as-synthesized sample bonded at 100°C, an inhomogeneous IMC formation dominated by grain boundary diffusion was observed. After High Temperature Storage of 1000 hours, the consumption of the Al bond pad resulted in the formation of irregular IMC layers. The variation of phases existed in a localized region was believed due to simultaneous growth of IMC by both grain boundary and volume diffusions. Moreover, the diffusion of Cu into Si was observed. This resulted in the formation of the mixture of Si + η phases in the affected sea region.
A Comparison Study between Friction Stir Welding and Metal Inert Gas Welding in Joining Similar Al-Al Strips
Authors: Dawood Hasan I. , Mohammed Kahtan S. , Rajab Mumtaz Y. , Ismail Nurafifah R.
Published: April 2014

In this study, two sets of pure aluminum strips 3 mm in thickness were friction stir welding (FSW) together in a regular Butt joint pattern. Two rotational speeds of 1750 RPM and 2720 RPM were utilized to perform the welding process. The transverse speed and the axial load were kept constant at 45 mm/min and 6.5 kN respectively. As a welding tool, cylindrical shoulder and pin geometry was selected. For comparison purposes other similar strip pair sets were butt welded using the conventional metal inert gas arc welding technique (MIGAW). The welding quality, power input, microstructure, macrostructure and the mechanical properties of the weld joints yielded from these two welding techniques were examined. The types of the fumes and the amount of the released gases during these two welding processes were measured and compared. The results proved that the solid state friction stir welding is clean, cost effective and environment friendly process as opposed to the conventional metal inert gas arc welding.
Photocatalytic Hydrogen Production from Water on Ga, Sn-Doped ZnS under Visible Light Irradiation
Authors: Yuliati Leny , Kimi Melody , Shamsuddin Mustaffa
Published: April 2014

Zinc sulfide (ZnS) has been reported to act as a photocatalyts to reduce water to hydrogen. However, ZnS could not work under visible light irradiation due to its large band gap energy. In order to improve the performance of ZnS, Ga and Sn were doped to ZnS. The series of Ga (0.1),Sn (x)-ZnS with various amounts of Sn (x) was prepared by hydrothermal method. XRD patterns suggested that the addition of Ga might reduce the crystallinity of ZnS, suggesting that Ga might inhibit the crystal growth or agglomeration of ZnS. On the other hand addition of Sn did not much affect the structure of the Ga (0.1)-ZnS. The DR UU-visible spectra confirmed the red shift of the absorption edge with the addition of Ga due to the reduced band gap energy, while the addition of Sn did not much shift the absorption edge of the Ga (0.1)-ZnS to longer wavelength. FESEM images showed that all the prepared samples have sphere-shaped particles and no remarkable change was observed with the addition of Ga or Sn. The photocatalytic hydrogen production from water was carried out at room temperature in the presence of sacrificial agent under visible light irradiation. While ZnS did not show activity under visible light, all the prepared Ga (0.1)-ZnS and Ga (0.1),Sn (x)-ZnS samples exhibited photocatalytic activity for hydrogen production. The highest hydrogen production was achieved on Ga (0.1),Sn (0.01)-ZnS, which activity was ca. three times higher than that of the single doped Ga (0.1)-ZnS. This study clearly showed that Sn acted as a good co-dopant to increase the photocatalytic activity of Ga (0.1)-ZnS for hydrogen production from water under visible light irradiation.
Aluminium/Floral Foam Laminated Composites under Flexural and Compression Test
Authors: Adnan Sinar Arzuria , Nurfarahain Dzainal , Firuz Z. , Nur Azni M.A.
Published: April 2014

This study is concerned on evaluation of laminated composites of aluminium (Al) sheet and floral foam (FF) under flexural and compression test. Effect of different layers of Al/FF laminated composites was evaluated. Epoxy and hardener was used as the adhesive to bind the surface between the Al sheet and FF. The information on the functional group that exists in FF during the formation of the foam was verified by Fourier Transform Infrared Spectroscopy (FTIR) analysis. From flexural and compression test, the mechanical properties decreased with the increasing number of layers of Al/FF laminated composites. The load cannot be distributed uniformly across the composite layer thus results in failure. Optical Microscope (OM) was used to see the adhesion between the layers of Al/FF laminated composites. One layer (1L) of Al/FF shows good adhesion while for four layer (4L) of the composites show phase separation and the excess adhesive around the interface. This shows that the adhesion between the layers also contribute to the failure of the laminated composite. FTIR analysis shows that the FF consists of amine group (at 3587.95 cm-1), alcohol group (at 3305.35 cm-1) and alkyl group (>900 cm-1) which is the main functional group found in polyurethane foam.
Galactose Consuming Microbes for Ethanol Production from Seaweed
Authors: Zakaria Nur Zatul 'Iffah , Arbain Dachyar , Ahmad Mohd. Noor , Dzahir Mohd Irfan Hatim Mohamed
Published: April 2014

Gracilaria sp. is one of macroalgae that contain high amount of sugar especially galactose. This galactose can be fermented into bioethanol by galactose-consuming microbes similar to the widely known ethanol production by yeast S.cerevisae. Hence the main objective of this study is to isolate galactose consuming microbes which capable of fermenting galactose into bioethanol. For this purpose, microbes-containing sample from seaweed culture were grown on galactose agar and tested for their survival as well as ethanol production capability. Seven isolated microbes belong to fungi and bacteria species were tested for their capability in fermenting galactose to produce ethanol. The concentrations of ethanol that have been produced by isolated microbes were analyzed by dichromate method whereas the consumption of galactose was determined by Dinitrosalicyclic acid (DNS) method. It was found that ethanol production resulted from fermentation by S1, S2, S3 and S4 were 0.80% (w/v), 0.74% (w/v), 0.81% (w/v) and 0.85% (w/v) respectively. Identification of these strains, as well as optimization of their ethanol fermentation are undergoing in our laboratory.
Synthesis of MCM-41 from Rice Husk Ash and its Utilization for Lipase Immobilization
Authors: Zainalabidin Nurhadijah , Mohd Salleh Noor Hasyierah , Arbain Dachyar
Published: April 2014

Mesoporous materials are favorable for enzyme immobilization due to their unique properties of large surface area, uniform pore system and functionalizable surfaces. Immobilization on these materials enhances enzyme stability, activity and resistance towards harsh environmental conditions such as temperature and pH. The present study deals with synthesis of mesoporous materials namely MCM-41. For that purpose, the MCM-41 was synthesized using cetyltrimethylammonium bromide (CTAB) as a template and extractable silica from rice husk ash as a silica source. The synthesis was performed under alkaline conditions to produce white fine solid particles, followed by grafting with 3-aminopropyltriethoxysilane and activation with carbodiimide before it was immobilized with lipase. Characterization of those fine particles using Nitrogen physisorption gives BET surface area, as BET, and the pore diameterto be 1184 m²/g and 2.58 nm respectively. Fourier Transform Infrared spectra show peak of SiO2, NH2 and COOH functional group which confirms the existence of those compounds in covalent bonding formation between amine-grafted MCM-41 and lipase enzyme. Immobilized enzyme shows an increase in pH stability when compared to free enzyme at fixed temperature of 20°C in time range from 30 to 180 minutes.
Synthesis of Mesoporous Silica Nanocomposites for Preparation of Gold Nanoparticles
Authors: Jalani Mohamad Azani , Yuliati Leny , Endud Salasiah , Lintang Hendrik O.
Published: April 2014

Gold nanoparticles (AuNPs) having particle size less than 10 nm can exhibit enhancement of surface area to give high activity such as in catalytic reaction. However, it is hard to synthesize AuNPs with small particle size due to the strong agglomeration. Herein we report that channels of mesoporous silica synthesized via the template sol-gel synthesis can be used to prepare AuNPs by calcination method. Mesoporous silica with an interpore distance of 4.1 nm was successfully fabricated as transparent thin film by using an amphiphilic trinuclear gold (I) pyrazolate complex as a template for the sol-gel synthesis. Upon calcination at 450 °C for 3 h, silica film nanocomposites showed red-shifting of surface plasmon resonance (SPR) bands from 518 (AuNPs from the bulk) to 544 nm owing to decreasing of the average particle size. The formation of AuNPs was also supported by the appearance of diffraction peaks of d111 at 2θ = 38.20° having a cubic phase. Moreover, transmission electron microscope (TEM) images and X-ray diffraction (XRD) peaks also showed smaller and more homogenous distribution of AuNPs.
Study on Synthesis and Characterization of Cu-Ni Doped TiO2 by Sol-Gel Hydrothermal
Authors: Bashiri Robabeh , Norani Muti Mohamed , Kait Chong Fai , Sufian Suriati
Published: April 2014

Titania (TiO2) as a semiconductor has been intensively studied during the last decades. Regardless of its superior photocatalytic performance and extensive environmental applications, it has a wide bandgap which lead to a photocatalytic activity only in ultraviolet (UV) irradiation. To shift the activity of TiO2 to visible region, a series of monometallic and bimetallic doped TiO2 was prepared with 10wt% total metals loading. The photocatalysts were synthesized by sol-gel associated via hydrothermal method. The properties of the photocatalysts such as crystal size, surface morphology, total surface area, chemical state of the elements, and bandgap were investigated by using thermogravimetric analysis (TGA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and BrunauerEmmettTeller (BET) measurement. XRD analysis showed that all samples displayed anatase (101) as a main phase of TiO2 with average crystal size between 10-16 nm in a good agreement with the TEM results. The FESEM images show spherical particles less than 20 nm in size. The BET results indicated that all samples are mesoporous. The band gap of Ni-Cu/TiO2 is reduced to 2.65 eV with more absorbance in the visible region compared to those of cu/TiO2 and Ni/TiO2.
Evolution of the Retrogression and Reaging Treatment on Microstructure and Properties of Aluminum Alloy (Al-Zn-Mg-Cu)
Authors: Naeem Haider T. , Ahmad Khairul R. , Mohammad Kahtan S. , Rahmat Azmi
Published: April 2014

In this study the evolution of the retrogression and reaging (RRA) heat treatment process on microstructure and mechanical properties of AA 7075 Al-alloys which produced by semi-direct chill (DC) casting process were investigated. Al-Zn-Mg-Cu alloys were homogenized at different heat treatment conditions, aged at 120°C for 24 h (T6), and retrogressed at 180°C for 30 min then re-aged at 120°C for 24 h (RRA). The results showed that this three-step process of the heat treatments, the mechanical properties of alloys was substantially improved. The highest ultimate tensile strength and Vickers hardness attained for the retrogression and re-aging about 530 MPa and 223 HV respectively. The precipitation strengthening is responsible about improve the strength under impact the retrogression and re-aging process.
Effect of Reagents Molar Concentration on CdS Thin Films Properties Grown by Chemical Bath Deposition under Microwave Irradiation
Authors: Husham M. , Hassan Z. , Mahdi M.A.
Published: April 2014

Nanocrystalline cadmium sulfide (CdS) thin films have been successfully grown onto glass substrate via chemical bath deposition (CBD) technique under microwave irradiation (MWI) as a heating source. Aqueous solutions of cadmium chloride (CdCl2) and thiourea [SC(NH2)2] were used as Cd+ and S- ion sources respectively. In this study, the effect of reactants molar concentration on the deposited thin films thickness and quality were investigated. Higher thickness was obtained for the film prepared with concentration of 10mM whereas; the lowest was for the film prepared using 11mM. Keywords: CdS, nanocrystalline thin films, molar concentration, properties.
Deformation and Energy Absorption Characteristics of Biomass Foam Composites
Authors: Nur Azni Mohd Azizan , Sinar Adnan Arzuria , Zainuddin Firuz , Supri A.G.
Published: April 2014

Deformation and energy absorption characteristic of biomass foam composites are important in crashwortyness efficiency. The type of foam that had been used in this research is polyurethane (PU) foam with plant-based filler which are turmeric powder (Curcuma Longa), charcoal powder, henna powder ( Lawsonia inermis) and lemon grass powder (Cymbopogon) that give natural color to the composites. The percentages of filler was specified to 10% by weight. PU foam was prepared by reaction of natural oil polyol and isocyanate with a ratio of 1 to 1.1 by weight. The mixture was stirred with 1500 rpm and was poured into the mould when mixture starting to expand. Band saw was used to cut the sample with desired dimension. The characterization of filler was done using Fourier Transform Infrared Spectroscopy (FTIR). Compression was tested using Ultimate Testing Machine (UTM) and scale to weigh the sample. Composites with henna filler have ductile like behavior that proved in stress-strain curved that show the rough line in the graph. Other composites have rigid like behavior which have a smooth line in a stress - strain curve.
Influence of RF Power in the Growth of Aluminium Zinc Oxide (AZO) Thin Films by RF Sputtering
Authors: Aliyu Mohammed Mannir , Islam Muhammed Aminul , Huda Qamar , Rahman Sajedur , Amin Nowshad
Published: April 2014

Aluminium doped zinc oxide (AZO) is fast becoming an important thin film material for applications as transparent conducting oxide (TCO) in several thin film solar cells, smart windows and many devices using touch screen displays. This is due to its good electrical and optical characteristics as well as lower cost and good abundance. Although sputtering is the general method for industrial fabrication of this material, but film characteristics depend strongly on fabrication processes. Thus, optimal films are obtained by optimization of the deposition conditions. In this work, we investigated the effects of RF deposition power on AZO thin films. Samples of similar thicknesses were grown under similar conditions in an RF sputtering chamber at different RF powers. The samples were then characterized using FESEM, AFM, UV-Vis, XRD and Hall effect measurement tools. Results indicate that the surface morphology is slightly affected with larger grain sizes obtained at higher RF powers. Also the surface roughness, average transmittance, conductivity and deposition rate all increase with the RF power. The lowest as-deposited resistivity of 15.3x10-3 Ω/cm was obtained, at the highest RF power of 100 W. This film also have the highest values of carrier concentration, mobility and figure of merit of 4.24x1020 cm-3, 0.96 cm2/V and 0.27x10-3 Ω respectively. This work highlights the significance of RF power in the fabrication of good quality AZO thin films.
Investigation on the Single-Ion Conductivity of PAN/Li-MMT Nanocomposite
Authors: Galvan Mitch Irene Kate N. , Diamante Junierose C. , Diaz Leslie Joy L.
Published: April 2014

In this study, PCNs were synthesized using Li impregnated montmorillonite (Li-MMT) in PAN matrix to promote single-ion conduction. Ion exchange resulted to 4782.5 ± 112.5 ppm Li+ ions impregnated to MMT. Then, Li-MMT was incorporated to PAN via solution intercalation method. The investigation on the structure of PAN/Li-MMT nanocomposites showed that PAN was partially intercalated with Li-MMT. Moreover, electrical conductivity measurements showed that the conductivity for PCN with 15wt% Li-MMT was 3.58x10-8 S/cm.
Characterization of Modified Multiwalled Carbon Nanotubes
Authors: Syuhaidah Rahmam , Mohamed Norani Muti , Sufian Suriati
Published: April 2014

Unique characteristics of MWCNT such as high porosity and high surface area make MWCNT as potential material to be explored in-depth through research. The role of MWCNT as CO2 adsorbent will be more efficient after modification with 3-Aminopropyl triethoxysilane (APTS) in order to obtain amine functional group. However, direct functionalization is not permissible due to the hydrophobic problem faced by pristine MWCNT. This complication can be resolved by liquid oxidation treatment using different types of oxidants such as nitric acid (HNO3), sulfuric acid (H2SO4), and mixture of nitric and sulfuric acid (HNO3/H2SO4). The characteristics of pristine MWCNT and modified MWCNT were investigated by analyzing the samples using scanning electron microscopy and energy dispersive X-ray spectroscopy (FESEM-EDXs), fourier transform infra-red (FTIR), and Raman spectroscopy technique. Higher degree of functionalization implies higher attachment of amine functional group for higher CO2 adsorption. Here, MWCNT sample treated with HNO3/H2SO4 and APTS recorded the highest degree of functionalization.
Analysis and Structural Investigations of CdS/Quartz Nanostructures
Authors: Al-Douri Y. , Hashim U.
Published: April 2014

CdS nanostructures deposited on quartz substrates with spin coating speeds 1000, 3000 and 5000 rpm and annealed at 800 °C are prepared by sol-gel spin coating technique. Ratio of cadmium to thiourea molar is 0.1:0.05 as an indication of nanostructured CdS formation with a grain size of 3.83 nm CdS nanostructures have been characterized by scanning electron microscopy (SEM) to research the morphology, respectively. Also, they have been analyzed using X-ray diffraction (XRD); the grin size, full width half maxima, miller indices, lattice constant a and c. The measured and calculated results showed a good agreement with other experimental and theoretical data.
Influences of Preheating Temperature on the Structural and Optical Properties of ZnO Thin Films by So-Gel Spin Coating Technique
Authors: Kamaruddin Sharul Ashikin , Sahdan Mohd Zainizan , Chan Kah Yoong , Nayan Nafarizal , Saim Hashim
Published: April 2014

The Zinc Oxide (ZnO) films were fabricated on glass coated with indium tin oxide (ITO) substrate by sol-gel spin coating technique. With regard to the preheating temperatures, the effects of growth mechanism ZnO films on the optical and structural properties were investigated. In this study, the preheating temperatures were varied from 250°C, 280°C, and 300°C. The X-ray diffraction (XRD) and ultraviolet-visible (UV-Vis) spectroscopy were used to examine the structural and optical properties of the ZnO films. The XRD results revealed that, the ZnO films are highly crystalline for all samples which are dominated by (002) peak orientation. Meanwhile, observation from optical results indicated that, the variation of transmittance spectra were turn out and it is proportional to the preheating temperatures used. Overall, we realized that the properties of the ZnO films in the sol-gel spin coating technique strongly depend on the preheating temperature and need to be considered as important factor to obtain the high-quality of the ZnO films. Keywords: Sol-gel, Zinc oxide film, X-ray diffraction
Critical Surface Tension of Cholesteryl Ester Liquid Crystal
Authors: Wan Omar Wan Ibtisam , Soon Chin Fhong
Published: April 2014

Cholesteryl ester liquid crystal was found to be non-toxic and it was recently applied as a cell traction force sensor. The reason for the affinity of the cells to this liquid crystal is unclear and required further investigation. This paper focused on determining the surface energy of the liquid crystals. A custom built contact angle measurement system and Fox-Zisman theory was applied to determine the critical surface tension of the cholesteryl ester liquid crystal. Eight different polar probe liquids were selected to determine the contact angle of the glass slides coated with cholesteryl ester liquid crystals. We found that the critical surface tension of the liquid crystal at 37.5 mN/m characterized the surface of the liquid crystal to be moderately hydrophobic. However, as reported in our previous work that the interaction of the liquid crystal and the cell culture media could re-orientate the amphiphilic molecules of the liquid crystals leading to the formation of lyotropic layers on the bulk cholesteric phase, therefore, making the surface to be hydrophilic. This then supported the formation of the hydrophilic layers that favors cell adhesion.
Fabrication and Characterization of 45S5 Bioglass® Composite Scaffolds
Authors: Shamsudin Suriani , Suhaida Mat Ghani , Sahid Sudirman , Wan Sulaiman Wan Ruzaini , Sabudin Salina , Yunos Darmawati Mohd
Published: April 2014

There are many challenges in designing and fabrication of synthetic tissue scaffold for osteochondral tissue engineering. A promising scaffolding material such as 45S5 Bioglass® has been extensively considered to construct scaffolds for this purpose. The 45S5 Bioglass® scaffold was fabricated using foam replication technique. The polyurethane foam was immersed in slurry of 45S5 Bioglass® and poly vinyl alcohol (PVA). The obtained green body was exposed for 1 hour at room temperature before oven dried at 60°C for 24 hours. The 45S5 Bioglass® composite scaffold was prepared by sintering the green body at 1050 °C for 2 hours, followed by dipping in PDLLA solution and dried at room temperature for 12 hours. Characterisations of the above scaffold were carried out using Extended Pressure Scanning Electron Microscope (SEM), Universal Tensile Machine (UTM) and X-ray diffraction (XRD). The SEM micrographs revealed the porous structure of the scaffold. The X-ray diffraction (XRD) spectrum showed the presence of Na2Ca2Si3O9 and (Na2Ca4(PO4)2SiO4 phases in the sintered scaffold. The result showed that the 45S5® Bioglass scaffold has compressive strength of 0.40 MPa with porosity of 88%. Bioactivity assessment in Simulated Body Fluid (SBF) for 7, 14 and 28 hours gave the formation of apatite layer on the scaffold.
Effect of Anodizing Voltage on the Formation of Porous Anodic Alumina on Al-0.5wt% Mn Alloys
Authors: Voon Chun Hong , Derman Mohd Nazree B. , Hashim U. , Foo Kai Loong
Published: April 2014

In this study, the effect of anodizing voltage on the morphologies, pore diameter and interpore distance on the porous anodic alumina formed on aluminium manganese alloy was reported. It was found that the anodizing influenced the morphologies and regularities of porous anodic alumina formed on aluminum-manganese substrate. Well ordered porous anodic alumina was obtained when anodizing voltage were 40 V and 50 V respectively. Disordered porous anodic alumina was formed when anodizing of 30 V and 70 V were applied during the anodizing process. Both pore diameter and interpore distance of porous anodic alumina increased linearly with the anodizing voltage.
Nanoscale DNA Sensing-Potential and Prospects
Authors: Ali Md Eaqub , Rahman Md. Mahfujur , Hamid Sharifah Bee Abd , Hashim Uda
Published: April 2014

Nanomaterials have attractive physico-chemical properties to create building block for special reorganization of DNA molecule. Nanomaterial based DNA sensors can be constructed with atomic precision, enhancing sensitivity and performance. Gold nanoparticles have excellent properties for tailoring size and shape to architect nanoscale structure, enhancing sensing and detection capacity by several magnitudes. Carbon nanotubes can immobilize probe DNA molecule and amplify signal transduction. Silica-nanoparticles based DNA detection inward significant attention because of their small size and ultra-scale sensitivity. Quantum dots have size-dependent adaptable photoluminescence with capability to perform multiplex detection. This paper has reviewed potential nanomaterials for DNA sensing application.
SERS-Active Nanomaterials: A New Dimension in Sensing Nucleic Acids
Authors: Ali Md Eaqub , Asing Asing , Hamid Sharifah Bee Abd , Hashim Uda
Published: April 2014

Detection of nucleic acids has wide ranging applications in biomedical, food, forensic and environmental sciences as well as in anti-bioterrorism. The development of highly sensitive, cost-effective and miniaturized biosensors and biochips requires advanced technology coupled with fundamental knowledge in chemistry, biology, and material sciences. In general, sensors and chips feature two functional components: a recognition element that provides selective/specific binding with the target analytes and a transducer component for signaling the binding event. An efficient sensor relies heavily on these two components for the recognition process in terms of response time, signal-to-noise ratio (S/N), selectivity, and limits of detection. Thus designing biosensors with higher efficacy depends on the development of novel materials to improve both the recognition and transduction processes. Surface enhanced Raman scattering (SERS)-active nanomaterials feature unique physicochemical properties that can be of great utility in creating new recognition and transduction processes for chemical and biological sensors, improving the S/N ratio by miniaturization of the sensor elements. The surface of SERS-active nanomaterials needs to be tailored and decorated for immobilizing marker biomolecules and integration with chromophores. This paper has extensively reviewed various SERS-active nanomaterials along with their synthesis, surface modification and characterization schemes for nucleic acid sensing applications with atomic precision.
Novel Design and Implementation of Portable Charger through Low-Power PV Energy System
Authors: Al-Mashhadany Yousif I. , Attia Hussain A.
Published: April 2014

This paper proposes a novel design for a solar-powered charger for low-power devices. The level of the charging current is controllable and any residue power is saveable to a rechargeable 9V battery. Two power sources (AC and solar) are used, and two charging speeds are possible. Quick charging is 20% of the battery output current (almost 180mA/hr) so the current is limited to 34 mA. Two types of cellular batteries (5.7V and 3.7V) can be charged. Normal charging is 10% of the cellular battery output current (almost 1,000mA/hr), so the charging current is limited to 100mA. The design uses only a few components so the system is cost effective besides being highly portable. It was simulated on MultiSim Ver. 11 before being implemented practically to validate it. The results from the simulation and the experiment show the designs sufficient feasibility for practical implementation.
Serine Sensor Based on Graphene Sheet Congo-Red Molecular Imprinted Polymer (GSCR-MIP) Organic Thin Film Transistor (OTFT)
Authors: Halim Nurul Farhanah Ab. , Ahmad M.Noor , Islam A.K.M. Shafiqul , Shakaff A. Yeon Md. , Zakaria Zulkhairi , Derman Mohd Nazree B.
Published: April 2014

Molecular imprinted is a technique to produce template-shape cavities in polymer matrix with memory of the template/target molecule for chemical sensor front-end. In this study, it has been shown that the incorporation of graphene sheets/Congo red (GSCR) has enhanced the performance of molecular imprinted polymer (MIP) serine sensor. The polymer is formed via photo-polymerization from methyl methacrylate acid (functional monomer), serine (template) and ethylene glycol dimethacrylate (cross-linker) together with GSCR. By introducing GSCR-MIP, GSCR-MIP OTFT chemical sensor demonstrates a good response when serine is introduced. The performance of GSCR-MIP OTFT serine sensor can be improved through the addition of GSCR, thus GSCR-MIP has high potentials for application in sensor fabrication.
Fabrication and Characterisation of the Electrical and Physical Properties of the Mask Printed Graphite Paste Electrodes on Paper Substrates
Authors: Zin Rosliza Mohamad , Soon Chin Fhong , Ghadafi Syalina , Mohamad Ali Riyaz Ahmad , Nayan Nafarizal
Published: April 2014

Heavy metal contamination in waste water is a problem of paramount concern. Instant measurement of the degree of contamination is the long term aim of this work. This project proposed the fabrication of mask printed graphite paste electrodes based on natural graphite and micronized graphite powder which has potential for sensing heavy metal in water. The graphite paste were prepared by mixing paraffin oil and graphite powder at certain ratios and they were coated via a mask on a paper substrate using squeegee method. A two-probe station was used to characterize the I-V curve of the mask printed electrodes, in which the result was used for determining the resistivity of the graphite paste electrodes. A field emission scanning electron microscope (FE-SEM) and energy dispersive X-ray spectroscopy (EDS) was used to investigate the surface structure of the graphite paste electrode and determining the purity of the carbon in the electrode. The result shows that natural and micronized graphite paste electrode has a mean resistivity of 1.69 x 10-3 Ωm and 1.25 x 10-3 Ωm, respectively. The slight difference found in the conductivity of both electrodes is associated with the particle gap size, density and dimension of graphite electrodes which are associated with the percolation theory.
Application of Taguchi Method in Designing a 22nm High-k/Metal Gate NMOS Transistor
Authors: Afifah Maheran Abdul Hamid , Menon P. Susthitha , Ahmad I. , Shaari S.
Published: April 2014

This paper reports on the application of Taguchi method in modelling a 22nm gate length high-k/metal gate NMOS transistor. The Nominal-the-Best Signal-to-noise Ratio (SNR) using Taguchis optimization technique was utilized to optimize the process parameters in determining the best threshold voltage (Vth) value where it was used as the evaluation variable. The high permittivity material (high-k) / metal gate device consists of titanium dioxide (TiO2) and tungsten silicide (WSix) respectively. The simulation work was executed using a TCAD simulator, which consist of ATHENA and ATLAS as a process and device simulator respectively. In this research, the Halo implantation tilting angle was identified as the most influencial factor in affecting the Vth with a percentage of 87%, followed by the oxide growth anneal temperature (8%), the metal gate anneal temperature (4%) and lastly the Halo implantation dose (1%). As a conclusion, the Halo tilting angle is the dominant factor in optimizing the process parameter. Meanwhile the Halo implantation dose can be considered as an adjustment factor in order to achieve the target Vth value of 0.289 V which is in line with projections made by the International Technology Roadmap for Semiconductors (ITRS).
Zeolite Supported Ionic Liquid Catalyst for the Synthesis of Nano-Cellulose from Palm Tree Biomass
Authors: Hamid Sharifah Bee Abd , Amin Md. Al , Ali Md Eaqub
Published: April 2014

Nanocellulose promises to be a very versatile material having wide range of biomedical and biotechnological applications including tissue engineering, drug delivery, wound dressings, medical implants, food, cosmetics, paper and textiles. The current methods for the synthesis of nanocellulose involve harsh chemical treatments which are perpetually hazardous to human and environment. Catalytic synthesis of nanocellulose might be a green approach. Among the various types of catalyst, ionic liquids, which are composed of both cations and anions and have low or negligible vapor pressure, are particularly promising. Ionic liquids also exhibit a relatively wide electrochemically stable window, good electrical conductivity, high ionic mobility, a broad range of room temperature liquid compositions, selective dissolvability to many organic and inorganic materials, and excellent chemical and thermal stabilities. In contrast, zeolite catalysts have been used in petroleum refineries for the removal of sulfur. Zeolite catalysts are also important for the synthesis of bulk chemicals, fine and specialty chemicals, fuels and chemicals. Acidic and metal modified micro porous zeolite catalysts have been used in several commercial processes in petroleum industry, fuel components, abatement of exhaust gas emissions and biomass upgrading, pharmaceutical and fine chemical industries. Currently, zeolite catalysts are synthesized in powder form and to make them industrially useful, such catalysts have to be mixed with a binder and formulated in different shapes. This paper reviewed the introduction, preparation, synthesis and application of nanocellulose from lignocellulosic palm biomass.
Design of Fully Integrated Impedimetric CMOS Biosensor for DNA Detection
Authors: Siu Fan Vinny Lam , Yusof Yusmeeraz
Published: April 2014

This paper described a label-free and fully integrated impedimetric biosensor using standard Complementary Metal Oxide Semiconductor (CMOS) technology to measure both capacitance and resistance of the electrode-electrolyte interface. Conventional impedance biosensors usually use bulky and expensive instruments to monitor the impedance change. This paper demonstrates a low power, high gain and low cost impedance readout circuit design for detecting the biomolecular interactions of deoxyribonucleic acid (DNA) strands at the electrode surface. The proposed biosensor circuit is composed of a transimpedance amplifier (TIA) with two quadrature phase mixers and finally integrated with 5μm x 5μm microelectrode based on 0.18μm Silterra CMOS technology process with 1.8V supply. The output value of the readout circuit is used to estimate the amplitude and phase of the measured admittance. The developed TIA can achieve a gain of 88.6dB up to a frequency of 50MHz. It also has very good linearity up to 2.7mA and the overall dynamic range is approximately 90dB.
Probing Electron Lifetime and Recombination Dynamics in Large Area Dye-Sensitized Solar Cells by Electrochemical Impedance Spectroscopy
Authors: Fakharuddin Azhar , Ahmed Irfan , Wali Qamar , Khalidin Zulkefli , Yusoff Mashitah Mohd , Rajan Jose
Published: April 2014

A number of nanocrystalline, mesoporous large area (~0.2- 2 cm2) dye-sensitized solar cells (DSSCs) are probed by electrochemical impedance spectroscopy measurements to realize their carrier dynamics such as charge transport resistance (RCT), electron diffusion coefficient (Dη), and electron lifetime (τn) by applying an equivalent electrical model. The experimental upshots reveal that the electron lifetime relates with the device physical parameters which was neglected in previous studies. It is also found that the RCT relates negatively with the device area i.e. it decrease upon increasing photo-exposed area. The observed lowering of current density (JSC) over a series of experiments upon increasing the photoelectrode area is attributed to the decrease in RCT. The charge carriers upon injection into semiconductor layer find increased diffusion pathways and eventually recombine with the hole species when characterized by lower carrier lifetime. The thickness of the electrode film does not play an effective role indicating that the dynamics of larger area DSSCs differs largely from those of a single cell. The experimental results available indicate that a nearly complete collection of charge carriers is possible in large area modules provided the physical dimensions of photoelectrode area are considered. The results from the study hints future directions to build high efficiency DSSC modules and further asserts considering the diffusion length in two-dimensions while fabricating larger area cells.
Fuzzy Logic Overcurrent Relay Using Sugeno Technique
Authors: Thiab Omar Sami , Abdulrazaaq Sami Thiab , Izham Zainal Abidin , Aidil Azwin Zainul Abidin
Published: April 2014

The overcurrent relay is the simplest and most economical type of protective relay, the relay is designed to operate when more than a predetermined amount of current flows into a particular portion of the power system. Time delay between relay's main zone and it's backup will keep the selectivity of the system, The inverse definite minimum time relay will calculate the time delay inversely proportional to the fault current level. This technique has some weaknesses where the time delay provided for a given case maybe too high and if the fault is not isolated immediately then damage could be caused to other connected equipment in the power system. This paper presents the fuzzy logic relay using Sugeno technique to determine the time delay, and using of symmetrical components application in detecting fault type, also it presents a comparison between times calculated by other techniques.
Modeling Development of a High-Sensitivity Escherichia coli O157:H7 Detection Based on SH SAW Sensor
Authors: Ten Seng Teik , Hashim Uda , Sudin Ahmad , Liu Wei Wen , Foo Kai Loong , Salleh N.H.M. , Hisham Hashim , Nazwa T.
Published: April 2014

Surface acoustic waves based devices were initially developed for the telecommunication purpose such as signal filters and resonators. The acoustic energy is strongly confined on the surface of the surface acoustic waves (SAW) based devices and consequent their ultra-sensitivity to the surface perturbation. This has made SAW permits the highly sensitive detection of utterly diminutive charges on the surface. Hence, SAW based devices have been modified to be sensors. Food contamination has become critical issue and sensitive detection devices are needed urgently as small amount of harmful bacterial pathogens such as Escherichia coli (E.coli) O157:H7with the dose fewer than 100 organisms in food products or water is enough to cause serious gastrointestinal illness to human. Therefore, ultra-high sensitive, label free biosensors have been designed in this research for the low concentration E.coli detection. After the saturated development in telecommunication filed, SAW sensors were developed for gas detections and have been moving towards biological detections recently. Shear horizontal surface acoustic wave (SHSAW), one of the SAW based types is most suitable for the liquid based application as it has the advantage of acoustic energy is not being radiated into liquid. Therefore, SHSAW device has the potential to provide high-performance sensing platform in this research. There have been a lot of complicated theoretical models for the SAW devices development since 1960 as signal filters and resonators such as from delta function model, equivalent circuit model, to the current SAW models such as coupling-of-modes (COM) model, P-matrix model and finite element analysis (FEA) model. However, SHSAW device in this research is not meant for signal filter or resonators but used for surface sensing purpose, therefore the simplicity method of the modeling is presented in the paper for the E.coli detection sensor development.
Low-Cost Sensors Array Based on Planar Electromagnetic Sensor Simulation for Environmental Monitoring
Authors: Mohamad Nor Alif Syarafi , Md. Yunus Mohd. Amri , Wahyudi Sophan , Sallehhudin Ibrahim
Published: April 2014

Agriculture sectors have increased in sizes and numbers due to the expansion of human population. Human population growth has caused the demand in food, cloth, transportation, shelter etc. to increase tremendously. Essentially speaking, those surpluses of demands will adversely affect the production of agriculture sectors. In order to obtain high yield, the farmers might be overusing the fertilizer for their crops. These overused fertilizers will be dissolved in the nearest water resources such as river, pond and well. Hence, the natural water resources will be contaminated by these overused fertilizers. In this situation, there is a need for a sensor which could determine the contamination level in natural water resources. This project proposed low-cost sensor arrays based on planar electromagnetic sensors to monitor the contamination in the natural water resources. The sensors consist of three electromagnetic sensors that have been constructed in three types of configuration array namely, parallel, star, and delta. The modeling and simulation of the sensors were done by using COMSOL Multiphysics 4.2 software. Each sensor’s input was assign to 10 Volt peak to peak voltages and then the impedance of each sensor was obtained. In practical application, the impedance of these sensors will determine the contamination level of the water under test. The contamination condition was simulated by changing the electrical properties of the environment domain of the model that suit contamination condition. The impedance of each sensor was tabulated according to the increasing of frequency of the supply voltages. Hence, the best configuration of the planar electromagnetic sensors array for detection of contamination inside the natural water will be determined based on the sensitivity. This type of sensors will provide the in-situ measurement system which will save the cost and consequently the time required for each sample.
Multi-Input Boost Converter for Hybrid PV and Wind Generator Systems
Authors: Buswig Y.M.Y. , Utomo Wahyu Mulyo , Haron Zainal Alam , Yi S.S.
Published: April 2014

A renewable energy source that works alone can’t achieve customers’ requirements for a stable power supply. Therefore, the paper proposes a multi-input converter for hybrid renewable energy system. This converter is designed for two input sources, PV and wind generator in order to design high efficiency and high performance converters for renewable energy applications. The proposed multi-input converter is composed by interleaved technique with two step-up converters and the two inputs are accommodated with some extra semiconductors, inductances and diodes. The modes of operation based on the status of the four switches, where S1 and S2 operate as main switches in order to deliver energy from both voltage sources. A constant output power to the load is provided by switching S3 switch, which guarantied the appropriate output voltage by reduce the ripple and improve the reliability. Simulations of multi-input converter has been performed using MATLAB/SIMULINK. The simulation results confirm the validity of the proposed method, which can be seen as a promising new topology that ensure multi-input converter suitable for renewable energy applications.
Micro-Gap Electrodes Fabrication by Low Cost Conventional Photo Lithography Technique and Surface Characterization by Nanoprofiler
Authors: Haisu M. , Hashim Uda , Humayun Q.
Published: April 2014

The fabrication of sensitive and selective nanodevices is one of the important challenges for future detection of low concentration single bio molecule. The current research article is one of the attempts to achieve such sensitive and selective micro-gap electrodes by simple, low cost controllable process. Therefore high sensitive chrome mask was designed for micro-gap design transformation to wafer samples. At first the positive photoresist namely PR-1 2000A was spin coated on the samples wafer at different rotation speed. Then by implementation of low cost conventional photolithography technique an initial structure of micro-gap was patterned on wafer sample. Finally by using surface Nanoprofiler the thickness of resist coated wafer samples were investigated. The obtained results show that the thickness of the resist is directly related with spin coating speed of spin coater.