bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanocomposites of Multi-Walled Carbon Nanotubes with TiO2 for High Photocatalytic Activity
Authors: Tan Tong Ling , Lai Chin Wei , Abd Hamid Sharifah Bee
Published: April 2014

Multi-walled Carbon Nanotubes (MWCNTs) coupled with TiO2 nanoparticles was successfully synthesized using sol-gel method at room temperature. Titanium isopropoxide and MWCNTs were selected as starting materials. The presence of anatase TiO2 phase in the MWCNTs/TiO2 composites was determined by XRD analysis. In addition, FTIR analysis was conducted to determine the chemical bonding of MWCNTs/TiO2 composites. Interestingly, it was found that the shifting of absorption edges of TiO2 nanoparticles towards to the visible-light region due to the incorporation of MWCNTs using UV-Visible spectroscopy. The photocatalytic activity of MWCNTs/TiO2 nanocomposites was demonstrated by the Rhodamine B degradation.
Highly Active Mesoporous Carbon Nitride for Removal of Aromatic Organic Pollutants under Visible Light Irradiation
Authors: Lee Shu Chin , Lintang Hendrik O. , Endud Salasiah , Yuliati Leny
Published: April 2014

In this work, we reported the photocatalytic activities of carbon nitride (CN) materials for removal of various aromatic organic pollutants under visible light irradiation. Both bulk carbon nitride (BCN) and mesoporous carbon nitride (MCN) were prepared similarly through thermal polymerization of urea precursor, except that the mesoporous structure was generated onto the MCN via hard template approach using silica nanoparticles. Successful preparations of both BCN and MCN were suggested from various characterization techniques using XRD, DR UV-Visible spectroscopy, nitrogen adsorption-desorption analyzer, and TEM. The prepared BCN and MCN were tested for removal of aromatic organic pollutants, which were benzene, phenol and salicylic acid under visible light irradiation. Both BCN and MCN did not exhibit any photocatalytic activities in the removal of benzene, but active for removals of phenol and salicylic acid. The structure stability and the presence of electron donating group on the organic pollutants were proposed to affect the photocatalytic removal reactions. Owing to the larger BET specific surface area, MCN showed much higher photocatalytic activity than the BCN for removal of phenol and salicylic acid.
Thermo-Physical Behaviour and Mechanical Properties of Experimentally Enhanced Rubberised Concrete Block
Authors: Najim Khalid B. , Al-Jumaily Ibrahim A.
Published: April 2014

The aim of the presented study is to investigate the thermo-physical behaviour and mechanical properties of mortar pre-coated crumb rubber concrete block. For this purpose, thermal conductivity, emissivity and effusively will be tested in addition to the specific heat capacity. Thereafter, dynamic calculator software will be used to study the behaviour of a wall that constructed using the suggested concrete block and a comparison with a normal concrete wall will be made. Compressive, splitting tensile and flexural strength were tested as well. The results show that concrete blocks which meet the requirement of strength can be produced with about 300 kg/m3 of crumb rubber aggregate.
Synthesis and Characterization of Polysulfone/Montmorillonite (PSF/MMT) Mixed Matrix Membrane for Gas Separation
Authors: Oh P.C. , Mansur N.A.
Published: April 2014

In this paper, flat sheet polysulfone (PSF) membrane and polysulfone/montmorillonite (PSF/MMT) mixed matrix membranes with different MMT contents were prepared by dry-wet phase inversion method. N-methyl-2-pyrrolidone (NMP) and deionized water were used as a solvent and coagulant, respectively. The morphology and structure of membranes were analyzed by scanning electron microscope. Thermogravimetric analysis was also performed to examine the thermal decomposition of the synthesized membrane. Results showed that MMT had a good dispersion in the PSF matrix.
Nucleation and Condensation Modeling of Metal Vapor in Laval Nozzle
Authors: Zhalehrajabi Ehsan , Rahmanian Nejat
Published: April 2014

Nucleation and condensation of mercury vapor has been investigated in various divergent angle and operating condition. Divergent angle has a great effect on droplet size at the end of nozzle. Influence of operating condition such as pressure and temperature on the size of droplet has been investigated. A one-dimensional mathematical model based on classical nucleation and growth has been developed to calculate the nucleation and condensation of mercury vapor. A mercury vapour turbine has been used in conjunction with a steam turbine for generating electricity. The mercury cycle offers an efficiency increase compared to a steam-only cycle because energy can be injected into the Rankine Cycle at higher temperature. The target of modeling is predicting the droplet size of mercury nanoparticles during rapid expansion. The results are verified by accurate experimental data available in the literature. The governing equations were solved using Runge-Kutta third-order numerical method in MATLAB software.
Radiation Shielding Characteristics of Concretes Incorporates Different Particle Sizes of Various Waste Materials
Authors: Azeez Ali Basheer , Mohammed Kahtan S. , Al Bakri A.M. Mustafa , Hasan Hana Ihsan , Abdulkareem Omar A.
Published: April 2014

In this study, the dependence of gamma-ray absorption coefficient on the particulate matter sizes of steel slag, iron fillings and steel balls incorporated concrete were examined. The contents of these fillers in concrete mix was kept constant to 35 wt. %. Only the filler particle size was varied during the tests. The particle size ranged from 0.2mm to 1mm for steel slags and the iron fillings and from 2.5mm to 10mm for the steel balls.The concrete samples were assessed for their anti-radiation attenuation coefficient properties. The attenuation measurements were performed using gamma spectrometer of NaI (Tl) detector. The utilized radiation source was Cs137 radioactive element with photon energy of o.662 MeV. The results showed that gamma-ray attenuation coefficient was inversely proportional to the filler particulate matter size. Likewise the mean free paths for the tested samples were obtained. Maximum linear attenuation coefficient of 1.102±0.263cm-1 was attained for the iron filling.The iron balls and the steel slags showed much inferior values. The concrete incorporates iron filings afforded the best shielding effect. The density, microstructure, homogeneity and particulate distribution of the concrete samples were examined and evaluated using different metallographic, microscopic and measurement facilities.
Study on Indoor Nitrous Oxide Gas Neutralization by Using Anatase and Rutile Nanotitania
Authors: Sapiee Aqilah , Meor Sulaiman Meor Yusoff , Mahdi E.M.
Published: April 2014

Nitrous oxide is generally emitted from industry through fossil fuel combustion thus giving adverse effect to human health and environments. Catalytic converter is the common method used to neutralize this hazardous gas but the high cost of precious metals had limited its application. Nanotitania could neutralize nitrous oxide by the photocatalytic phenomenon and the material is effective as it has small band gap energy and large surface area. In this study, we produced both anatase and rutile crystalline phase nanotitania from a local titanium mineral as the starting material. A significant improvement to the properties of our nanotitania is due to the present of naturally doped neodymium and zirconium ions that are present in the titanium mineral. This make the band gaps for both anatase and rutile to be smaller and effective in photocatalytic process. Three different nanotitania formulations, pure anatase, pure rutile and mixed rutile and anatase phases, were tried in the study and the results showed that all these three formulations were able to neutralize the nitrous oxide within a very short duration. Comparative study was then performed with a blank sample and the result shows there is still significant amount of nitrous oxide present after the 2 hours run.
Tensile Properties, Swelling Behaviour and XRD Characteristic of R-HDPE/Tyre Dust and R-HDPE/Chicken Feather Fiber Composites
Authors: Aizat Emy Aizat , Supri A.G.
Published: April 2014

Effect of filler loading on tensile properties, swelling behavior, and XRD characteristic of R-HDPE/tyre dust (TD) composites and R-HDPE/chicken feather fibers (CFF) composites were studied. The both composites were prepared with Brabender Plasticorder at 160°C and rotor speed of 50 rpm. The R-HDPE/TD composites gave a greater value of tensile strength, and swelling behavior resistance compared to R-HDPE/CFF composites. X-ray diffraction analysis shows the R-HDPE/TD composites have lower value of interparticle spacing (d) than R-HDPE/CFF composites. This indicated better interaction between tyre dust and R-HDPE matrix. Keywords: Chicken feather fiber, recycled high density polyethylene, tyre dust
Biosorption of Cd(II) from Water by Moringa oleifera Leaves
Authors: Ali Eman N.
Published: April 2014

Cadmium is one of the most toxic metals affecting man, animals, and plants. It is considered one of the priority pollutants, its excretion from the body is very low, and it has synergistic toxicity with other metals. Therefore, cadmium from surface water and wastewater where the cadmium level is high must be treated. This work was done to study the biosorption of Cd (II) from water using Moringa oleifera leaves, as a natural, low cost biosorbent, and environmentally friendly without any modification. The dosage and the particle size of the natural biosorbent were studied as well as the concentration of Cd (II), and pH. The synthetic water with initial turbidity of 200 NTU was used and the Cd (II) concentration was 1ppm, and 3ppm. Different dosages of Moringa oleifera leaves powder of (0.10 to 10 g/L) were added with different particle size of Moringa oleifera leaves (<125, <250, <500, and >500 μm) at room temperature. The AAS was used to measure the residual Cd (II) in the supernatant after treatment with Moringa oleifera leaves powder. It was observed that the removal of Cd (II) was increased by increasing the natural biosorbent dosage, while the particle size and the pH has no effect on the removal efficiency. Therefore, it is concluded that the Moringa oleifera leaves powder can be used as a natural biosorbent without any chemical modification and can be used directly after grinding without sieving to different sizes. The best removal of 1ppm, and 3ppm Cd (II) was at dosage of 8g/L, and 10g/L from fresh grinded leaves, respectively.
Supramolecular Hydrogen Bonding Interactions of Novel 1,3,5-Benzenetricarbonyl Trisubstituted Alkyl for Anion Sensor Applications
Authors: Matmin Juan , Yuliati Leny , Shamsuddin Mustaffa , Lintang Hendrik O.
Published: April 2014

Herein we report the first example of benzene-1,3,5-tricarboxamide bearing hydrophobic aminododecane side chains (1) which spontaneously forms supramolecular network by a hydrogen bonding interaction. The compound 1 was synthesized by Schotten-Baumann reaction of 1,3,5-benzenetricarbonyl trichloride and 1-aminododecane in the presence of N,N-diisopropylethylamine. Nuclear Magnetic Resonance (NMR), Mass Spectrometry (MS), and Fourier Transform Infrared (FTIR) spectroscopies have proved the successful synthesis of 1 in 93% as white powder solid. The supramolecular organization was successfully utilized for sensing of nitrate anions by deformation of the hydrogen bonding to form inactive nitroso groups.
Visible Light Photodegradation of Diisopropanolamine Using Cu/TiO2 Photocatalyst: Effect of Metal Loading
Authors: Ramli Raihan Mahirah , Kait Chong Fai , Omar Abdul Aziz
Published: April 2014

Cu doped TiO2 at different metal loading was successfully prepared and investigated. Characterization of the prepared photocatalysts was carried out using X-ray diffraction (XRD), diffuse reflectance UVVis spectroscopy (DRUVVis) and scanning electron microscopy (SEM). Photodegradation study of aqueous diisopropanolamine solution (1000 ppm) using the prepared photocatalyst showed significant COD removal under visible light irradiation. The photocatalyst with 1.5 wt% Cu gave the highest COD removal of 45 %.
Study of Titanium Dioxide Thin Film by Sol-Gel Method
Authors: Nadzirah Sharipah , Hashim Uda , Malihah N.
Published: April 2014

Titanium dioxide (TiO2) thin films based interdigitated electrodes (IDEs) have been synthesized using sol-gel method with hydrochloric acid (HCl) as catalyst. The prepared TiO2 solution has been deposited onto silicon dioxide (SiO2) substrates via spin-coating technique. Film was annealed at 500 °C and aluminium (Al) IDEs have been fabricated. Finally the X-ray diffraction (XRD) shows high intensity of both anatase and rutile peaks exist on 10 nm TiO2 thin film. Average crystallite size of the nanoparticles is seen to be 25 nm. UvVisible spectroscopic (UvVis) technique was used for the transmittance spectra characterization of the sample.
Fresh State Behaviour of Cement Paste Containing Nano Kaolin
Authors: Muhd Norhasri M.S. , Hamidah M.S. , Fadzil A. Mohd , Abd Halim A.G. , Zaidi M.R.
Published: April 2014

The application of nanomaterials in cement by replacement method in concrete is becoming a trend in cement research. The utilisation of nanosilica, nanoalumina, titanium oxide and others are proven to enhance properties of concrete. The major effect of nanomaterials is its size in which it contributes to the packing theory due to increase in the surface area. nanokaolin which comes from kaolin, was tansformed to the nanoform by using high energy milling. The process of developing nanokaolin by using high energy milling is referred to process top to bottom approach in nanoprocessing technique. In this research, the nanokaolin will be used as an additive in cement by 7% weight of cement. Four (4) cement replacement materials catered by using metakaolin on weight basis from 0, 10%, 20% and 30% will also be adopted. To determine the fresh state, cement paste contains nanokaolin and metakaolin are tested its standard consistency and setting time. The effect of the inclusion of the nanokaolin as additive in cement paste that also contains metakaolin as cement replacement material will be investigated. It was found the inclusion of 7% nanokaolin increases the water demand of the cement paste level of metakaolin replacement. In addition to that, the setting time namely initial and final set was been delayed as compared to that of plain OPC. The nanoparticles of nanokaolin and also finer particles of metakaolin increase the surface area and refining the internal structure of cement paste which reduce the flow capabilities of cement paste containing nanokaolin and metakaolin.
Phase Evolution and Crystallite Size of Ni0.25Zn0.75Fe2O4 at Different Calcination Temperatures
Authors: Guan Beh Hoe , Soleimani Hasan , Yahya Noorhana , Latiff Noor Rasyada Ahmad
Published: April 2014

The effects of calcination temperature varying from 700 to 1100°C on the phase evolution and crystallite size of Ni0.25Zn0.75Fe2O4 synthesized using Sol-Gel technique have been investigated. XRD results showed that the Fe2O3 phase was formed in Ni0.25Zn0.75Fe2O4 in the lower calcination temperature. The crystallization increased as the calcination temperature increased and the crystallite sizes of the Ni0.25Zn0.75Fe2O4 calculated from Scherrer equation were found to be ranged from 16 to 62 nm which increased when calcination temperature increase. Raman results further confirmed the presence of spinel structure in the samples.
Determination of Morphology of Poly(3-hexythiophene) with Nanosphere- and Nanorod-Shape of Zinc Oxide
Authors: Aziz Azyuni , Naning Fatin Hana , Malik Syed Abdul , Zamiri Reza
Published: April 2014

Morphology of thin film poly (3-hexylthiophene) (P3HT) embedded with nanosphere-and nanorod-shape Zinc Oxide (ZnO) has been studied. We deposited the materials on quartz substrate using spin coating technique. The morphology of P3HT: ZnO thin films were investigated using Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray emission spectroscopy (EDX) and RAMAN Spectroscopy and compared. Based on size and shape of both ZnO, it can be seen that nanospheres in P3HT was found to be better than ZnO nanorods in P3HT.
Morphology and Mechanical Properties of NiZn Ferrite/Thermoplastic Natural Rubber Composite
Authors: Tarawneh Mou'ad A. , Haji Ahmad Sahrim , Jiun Yu Li , Dweiri Radwan , Hassan Ibrahim N.
Published: April 2014

In this paper the polymer nanocomposite of nickel zinc (NiZn) ferrite nanoparticles incorporated into the thermoplastic natural rubber nanocomposite (TPNR) were prepared via melt blending method. The effect of different NiZn loading (2-10 wt%) on morphology, tensile and dynamic mechanical properties of the obtained composites was investigated. It was found that NiZn ferrite is well dispersed in the thermoplastic natural rubber matrix. The tensile results indicated that filler loading has improved the tensile strength and Youngs modulus of the nanocomposite. However, the elongation at break decreased with increasing the percentage of NiZn. Dynamic mechanical test showed that the highest storage modulus is at 8 wt% filler. Any further increment of the filler content leads to the formation of agglomerate hence affecting the properties. The Scanning electron micrograph (SEM) micrographs reveal aspect ratio and filler orientation in the TPNR matrix also strongly promoted interfacial adhesion between the filler and the matrix to control its properties.
Bimetallic Fe-Ni/Zeolite β Catalysts for Hydrogen Generation from Steam Gasification of Palm Kernel Shell
Authors: Ramli Anita , Misi Siti Eda Eliana , Mohamad Mas Fatiha , Yusup Suzana
Published: April 2014

In this study, the potential usage of PKS as a direct source for hydrogen production is being explored in the presence of bimetallic Fe-Ni/Zeolite β (BEA) catalyst. The catalyst was prepared by co-impregnation method and calcined at temperatures between 500-700 oC to study the effect of calcination temperatures on the gas compositions from steam gasification of PKS. The textural properties and crystalline phase present were characterized using BET and X-Ray Diffraction. The catalysts were tested in steam gasification of PKS in a fixed-bed microreactor at 700 oC using 0.3 g catalyst and 0.9 g PKS. The steam to PKS ratio was 4:1 (vol) while steam to Ar ratio was 1:6 (vol.). The Fe-Ni/BEA catalysts possess lower surface area, higher pore volume and larger pore diameter as compared to the bare BEACalcination temperature is found to contribute to the crystallization of the prepared catalysts where high crystallization of Fe and Ni was observed in Fe-Ni/BEA (700) catalyst with the formation of NiO and NiFe2O4 phase. Fe-Ni/BEA (700) shows the highest composition of H2 gas produced with 76.32 vol% H2, 18.72 vol% CO2, 4.96 vol% CO and the absence of CH4. This shows that the steam gasification of PKS in the presence of Fe-Ni/BEA (700) has a potential to replace the commercial H2 production via methane reforming process.
Photoluminescence Studies on Spray Pyrolysis Deposited ZnO-SnO2 Mixed Thin Films
Authors: Tharsika T. , Haseeb A.S.M. Abdul , Sabri Mohd Faizul Mohd
Published: April 2014

ZnO-SnO2 mixed thin films were prepared by the spray pyrolysis technique using different molar ratios of zinc and tin in the starting solution. These mixed thin films were analysed by X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). XRD patterns of mixed thin films indicate the presence of tetragonal casseterite structure of SnO2 and hexagonal wurtzite phase of ZnO. The grain sizes of mixed films were calculated from XRD patterns and found to be in the range of 17- 84 nm. Mixed thin films exhibit smaller grain size compared to that of pure thin films. Ultraviolet and visible emission peaks were observed in photoluminescence studies of these thin films. The relative contribution of the emission bands occurring from different kinds of defects is described in detail. UV emission peaks were mostly affected by the influence of ZnO. Blue shift in UV emission peaks suggests a reduction in grain size in mixed thin film and bandgap modulation caused by SnO2.
Effects of Ageing Time of ZnO Sol on Properties of ZnO Films by Sol Gel Spin Coating
Authors: Norhidayah Che Ani , Kamaruddin Sharul Ashikin , Nayan Nafarizal , Tawil Siti Nooraya Mohd , Sahdan Mohd Zainizan
Published: April 2014

In recent years, there are many techniques developed to synthesize zinc oxide (ZnO) films. However, among the synthesis methods available, sol-gel has the most advantageous which offers cost effective features. In the present work, ZnO films were prepared by solgel spin coating technique. The effects of solution ageing times which varies at 2h 15 min, 3h 30 min and 24h were investigated. The structural, morphological and optical properties were studied using an x-ray diffractometer (XRD, Bruker D8 Advance), atomic force microscope (AFM, Tenko XE-100) and ultra violet-visible spectrophotometer (UV-Vis, Shimadzu UV 1800), respectively. Based on the XRD measurement, it was revealed that ZnO films were polycrystalline with hexagonal wurtzite structure. The crystallite size is in the range of 34.4 ~ 28 nm which decreased with ageing time increment. On the other hand, the AFM analysis revealed that the surface roughness of the films increased due to the increment of ageing times. Optical transmittance spectra indicate that all films were transparent (>75%) in the visible range which slightly improved with increasing of ageing times. The optical band gap was estimated to be around 3.24 ~3.26 eV using Taucs plot. We revealed that the ageing time of ZnO sol influenced the material properties of ZnO films. Based on our finding we proposed that 24h ageing time is optimum for the fabrication of high quality ZnO films.
Enhanced Photoconductivity and Antibacterial Response of Rubber-Grade ZnO upon UVA Illumination
Authors: Ann Ling Chuo , Mahmud Shahrom , Bakhori Siti Khadijah Mohd , Sirelkhatim Amna , Mohamad Dasmawati , Hasan Habsah , Seeni Azman , Rahman Rosliza Abdul
Published: April 2014

Ultraviolet-A (UVA) radiation is present in sunlight and have been associated with various types of human skin cancers. In this study, rubber-grade zinc oxide (ZnO) powder was used as the targeted materials to study its UVA photoresponse as well as its antibacterial function. ZnO powder was synthesized using French process. The morphological structures of the samples were investigated using field emission scanning electron microscopy and transmission electron microscopy. The dominant morphology of the sample was micro/nanoplate. The optical bandgap of the ZnO sample is 3.19 eV based on the UV-Visible measurement. Current-voltage measurement was conducted to study the effect of UVA (390 nm) illumination on the photoconductivity of the ZnO pellet. Photoconductivity was observed to increase significantly under UVA exposure due to light absorption on the surface of ZnO to raise the electrons across the bandgap. The current response of the UVA-induced also revealed the small persistent photoconductivity after the UVA light was turned off. Besides, higher voltage bias would lead to higher current flow under the same intensity of UVA exposure. According to the antibacterial test towards Staphylococcus aureus, the percentage inhibition of the bacterial after 24 h incubation increase when the concentration of ZnO suspension increases. The UVA illumination had improved the inhibition of the bacterial growth. This is due to the excitation of ZnO and increasing of free charge carriers in the solution, leading to potential distortion to the membrane surface of the bacteria. ZnO powder performed high absorption of UVA and they are not only can be used to block the UVA sunlight, but also have higher antibacterial capability under UVA excitation.
Effect of Blends Ratio on Mechanical and Morphological Properties of LDPE/Thermoplastic Soya Spent Powder Blends
Authors: Nuradibah M.A. , Ting Sam Sung , Noriman N.Z. , Ismail H.
Published: April 2014

This study investigates the properties of blends made from low density polyethylene (LDPE) with various levels of thermoplastic soya spent powder (SSP). The thermoplastic TPSSP content was varied from 5 to 20wt % whereas epoxidised natural rubber with 50 mol % (ENR 50) act as compatibilizer to improve the interfacial adhesion between low density polyethylene and thermoplastic TPSSP. The effect of the addition of ENR 50 on the LDPE/thermoplastic TPSSP was measured by using tensile test and thermal behaviour. The tensile strength and elongation at break (Eb) decreased with increasing TPSSP content. However, the addition of ENR 50 resulted in the increment of tensile strength and Eb LDPE/TPSSP blends.
Modeling of the Electronic Properties of Hexagonal Semiconductors
Authors: Arif Ghassan E. , Abdullah Farah Aini , Al-Douri Y.
Published: April 2014

This paper seeks to investigate the solvability of physical problem by utilizing the mathematical theory of differential equation. A new mathematical model based on mathematical modeling and differential equation is created. The objectives of this work sets up to model ionicity factor based on lattice constants (c/a) of hexagonal structure semiconductors using density functional theory (DFT) of full-potential linear augmented plane wave (FP-LAPW) within Engel Vosko-General Gradient Approximation (EV-GGA). Our determined values are in agreement with experimental and theoretical results.
Synthesis of Biodegradable Cellulose-Chitin Polymer Blend from Portunus pelagicus
Authors: Poblete Myra Ruth S. , Diaz Leslie Joy L.
Published: April 2014

Disposal of petroleum-based plastics has become a major concern due to its resistance to chemical, physical and biological degradation. As such, the production of an alternative biodegradable material from renewable sources is beneficial. This study aims to produce a polymer blend film, of enhanced formability and durability, from cellulose and chitin, the two most abundant naturally-occurring biodegradable polymers in the environment. Chitin was initially extracted from Portunus pelagicus shells through demineralization and deproteinization. The crude chitin is of comparable crystallinity with the commercially-available. However, other proteins were speculated to be present as indicated by the extra peaks in the XRD profile. This was then followed by the dissolution of the polymer powders in LiCl/DMAc, blending, casting, forming, cold-pressing and drying. The independent variables considered were cellulose-chitin ratio and the forming time. From the results, samples formed after 24 hours are relatively thinner, softer and more flexible. In addition, the best sample with UTS at 27.36 MPa was that of 80:20 cellulose-chitin, while the worst at 14.79 MPa was that of 20:80 cellulose-chitin both formed after 24 hours. ANOVA revealed that neither the main factors nor the interaction significantly affected the measured values. Lastly, thermal and biological degradation tests showed that the film started to degrade at 308°C and supported 4.9 x 103 and 3.8 x 104 CFU of mold and bacteria, respectively.
Nanoclustered Gold: A Promising Green Catalysts for the Oxidation of Alkyl Substituted Benzenes
Authors: Ali Md Eaqub , Rahman Md. Motiar , Hamid Sharifah Bee Abd
Published: April 2014

Catalytic oxidation of alkyl substituted benzenes is an essential route for the synthesis of a number of important chemicals, perfumes, drugs and pharmaceuticals. The oxidation products of ethyl benzene are important precursors for a wide range of pharmaceuticals and synthetic materials. Acetophenone and 1-phenylethanol are two oxidation products of ethyl benzene which are the precursors of optically active alcohol, benzalacetophanones, hydrazones and so on. However, the oxidations of alkyl substituted benzenes have been remaining a challenging task. This is because of the limitations of an appropriate catalyst and requirement of corrosive chemical treatments (potassium permanganate/dichromate and ammonium cerium nitrate) which are hazardous and environmentally unfriendly. The current industrial practice in the oxidation of ethyl benzene unfortunately involves high temperature thermal autoxidation in the absence of catalysts. Although few catalysts have been tested for the oxidation of ethyl benzene, many of them found to be inefficient. For example, cobalt (II) oxide-immobilized on mesoporous silica (Co/SBA-15) was used to catalyze oxidation of alkyl benzene at high temperature (125-150°C) but only 70% conversion was obtained after prolong treatment at 150°C. Additionally, the catalyst formed mixed uncontrolled oxidation products like 1-phenylethyl hydro peroxide, benzoic acid, acetophenone and phenyl ethanol. Carbon/silica/metal oxide supported nanoporous gold is a promising green catalyst for heterogenous molecular transformation. This is because of their three dimensional open pore network structures, high surface to volume ratio, high reusability, distinct optolectronic and physio-chemical properties. Mesoporous carbon/silica/metal oxide thin film supports provide increase dispersion of metal nanocatalysts and facilitate transport of molecules, ions or electrons through the nanopores/nanochannels, enhancing product yields with minimum cost and time. This paper has reviewed various gold-skeleton green catalysts and their preparation and mechanistic schemes for the selective oxidation of alkyl substituted benzenes.
Influence of Solution Temperature for Hydrothermally Grown Zinc Oxide Nanorods
Authors: Nadarajah Kalyani , Yern Chee Ching
Published: April 2014

Well-aligned arrays of vertically oriented ZnO nanorods were synthesized using hydrothermal method using equal molar concentration of zinc acetate hexahydrate (Zn (CH3COO)2.6H2O) and hexamethylenetetramine (C6H12N4) at various deposition temperatures. The resulting nanorods were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence (PL), and UV-vis spectrophotometer. XRD and FESEM results indicate that the crystallinity improved for nanorods grown at 85 °C. The preferred growth direction of these nanorods is in (002) direction. However, the nanorods were grown at 55 °C shows poor crystalline characteristics. Typically, these nanorods have grown up to 1000 nm with the diameter range of 25-50 nm. The obtained ZnO nanorods exhibit a weaker UV emission peak located around ~380-390 nm and a relatively stronger yellow-red emission band located at 625 nm to 675 nm.
Surface Morphology and Electrical Properties of Al:ZnO Films Deposited by Spin Coating Process
Authors: Sahdan Mohd Zainizan , Kamaruddin Sharul Ashikin , Chan Kah Yoong , Hashim Uda , Nayan Nafarizal , Saim Hashim
Published: April 2014

Aluminium (Al) doped zinc oxide (ZnO) has been considered as one of the promising transparent conducting oxide for wide applications in electronic devices. In this investigation, sol-gel spin coating process were employed to fabricate Al:ZnO on glass coated with indium tin oxide (ITO) substrate. In order to expose the effects of aluminium concentration on the structural and electrical properties of the ZnO films, different Al concentrations (1 at.%, 3 at.% and 5 at.%) were used. A field emission scanning electron microscope (FESEM) and a two point probe were employed to examined the material properties of the Al:ZnO films. Through the FESEM results, the Al:ZnO films show different morphologies behaviour with increasing the Al concentrations. Besides, the electrical conductivity was increased by increasing the dopant source and the lowest resistivity was obtained at 5 at.%. In general, the Al concentration exerts strong influence on the ZnO films properties. Keywords: Transparent conducting oxide, X-ray diffraction, sol gel
Low Temperature Joining of Copper by Ag Nanopaste: Studies on the Strength Behavior
Authors: Hausner Susann , Weis Sebastian , Elßner Michael , Wielage Bernhard
Published: April 2014

Nanoparticles exhibit a decrease in sintering and melting temperature with decreasing particle size. The utilization of this effect is of great interest for joining at low temperatures. First, the paper identifies possible applications for joining and their significance. Furthermore, a commercially available Ag nanopaste is characterized with respect to its thermal properties and strength behavior. Subsequently, it is qualified for joining at low temperatures. The shape, distribution and size of the nanoparticles are determined using transmission electron microscopy (TEM). The thermal behavior is characterized by differential scanning calorimetry (DSC) and thermogravimetry (TG). Furthermore, first examinations of strength properties were executed for the base material copper in order to characterize the influence of different process parameters on joining strength. The analyses show that the nanopaste has a great potential for joining at low temperatures. It is verified that the organic shell of the nanoparticles oxidatively decomposes at temperatures of about 410 °C followed by a sintering process. The sintered microstructure exhibits the thermal properties of bulk silver. It is also shown, that it is possible to produce joints at even lower temperatures of about 300 °C, whose thermal resistance and joint strength is significantly superior to conventional soldered joints.
Obtaining Efficiency Porous Ceramics with Controlling Size of Porosity
Authors: Korjakins Aleksandrs , Upeniece Liga , Bajare Diana
Published: April 2014

Anxiety of society about global warming is increasingly growing and interest about construction materials that are less harmful to the environment is growing as well. Manufactures and scientists are urged to think about the usage of more effective resources, which are available and necessary for production, as well as to find possibilities and solutions for the decrease of primary energy resource depletion by producing ecological materials. Clay is one of local raw materials that can help solving growing problems by production of ceramic materials and their products, as well as more widely distributed sediments, which mainly form the upper part of Earth’s crust. Alongside traditional ceramic materials, porous ceramics are also widely researched, becoming an increasingly popular material in the world, mainly owing to their wide possibilities of usage in different technical and technology industries – from construction to mechanical engineering, health industry and even space technology. Obtaining porous ceramics using different kind of burnable fillers, such as natural products obtained as waste from agricultural industry, as well as controllable form products obtained from polymers, allow to form desirable porous structures within wide ranges: with pore dimensions starting from some micrometers up to 2-3 millimeters. Porous ceramic materials obtained within this research are breathing, they are thermostable materials, resistant to thermal impacts, corrosion and are easy in processing. During the presented research porous ceramics were produced using different kinds of burnable fillers. The optimal burning treatment was developed for obtaining required mechanical properties of porous ceramics. The physical-mechanical properties of obtained ceramics were evaluated.
Characterizations of Nitrogen Doped Cupric Oxide Thin Films Deposited on Different Substrates for Solar Cell Applications
Authors: Ooi Poh Kok , Ahmad Mohd Anas , Ng Sha Shiong , Abdullah Mat Johar
Published: April 2014

In this work, structural, optical and electrical properties of nitrogen doped (N-doped) cupric oxide (CuO) thin films deposited on <100> orientated n-type silicon, glass and polyethylene terephthalate substrates using reactive radio frequency sputtering system were investigated. X-ray diffraction results revealed that all films exhibited monoclinic CuO(-111) and have only slightly different structural properties for various substrates. Field effect scanning electron microscopy shown N-doped CuO on Si and glass are denser than on PET substrates and all have nanotriangle-like structure morphologies. The N-doped CuO thin films have an indirect band gap of around 1.30 eV. The resistively, carrier concentration and hall mobility of the N-doped CuO thin film on glass were 1.05 kΩ.cm, 6.70 x 1014 cm-3 and 8.86 cm2/V-s respectively. Furthermore, palladium formed ohmic contact characteristics for N-doped CuO on glass and PET but exhibited schottky contact characteristics for N-doped CuO on Si.
Photoconductive Carbon Nanotube (CNT): A Potential Candidate for Future Renewable Energy
Authors: Hamid Sharifah Bee Abd , Das Rasel , Ali Md Eaqub
Published: April 2014

Human population has always been advocated to use exosomatic energy, exist in abundance in Mother Nature. As of today world's population has reached to 7.1 billion, which will be exceeding 8.0 billion by 2050. To fulfill the energy demand of increasing population, world existing energy should be increased by >50% by 2050. The question is do we have enough energy resources to meet the future energy demand Secondly, the use of reserved gas, oil, coal and other carbon-based energy sources would continue to emitgreenhouse gases which are estimated to warm up the world by 2°C by 2020, raising the sea level which will dwindle the world cultivable land. This paradigm shift has called foreffective, sensitive and advanced technologies dealing with the production, harvesting, conversion and distribution of renewable energy to meet the future energy needs. This paper has highlighted the potential applications of carbon nanotube (CNT) based composites to harvest the unlimited solar energy into electrical, mechanical and other forms of useful energy for human benefits. The competitive performances of CNTs in solar cells would build multibillion dollar energy market using green chemistry principles, reducing green house emission and ensuring enough energy for the future generations.
Experimental Analysis and FEM Simulation of Novel Finned Loop Heat Pipe
Authors: Gunnasegaran Prem , Abdullah Mohd Zulkifly , Shuaib Norshah Hafeez
Published: April 2014

Experiments are conducted to investigate heat transfer characteristics of finned loop heat pipe (FLHP) for heat input range from 20 W to 100 W. The experiments are carried out by manufacturing the FLHP, which the setup consists of a water tank with pump, a flat evaporator, condenser installed with two pieces of fans and air flow fins, two transportation lines (vapor and liquid lines), copper pipe sections for attachment of the thermocouples and power supply. The unique of the current experimental setup is the vapor and liquid lines of FLHP are made of transparent plastic tube to visualize the fluid flow patterns. In this study, the total thermal resistance (Rt) is estimated for both natural and forced convection modes under steady state condition, by varying the air velocity from 2 m/s to 10 m/s. The coolant velocity and heat input to achieve minimum Rtare found out and the corresponding effective thermal conductivity is calculated. The transient temperature distribution in the FLHP is also observed. The experimental observations are verified by simulation using Finite Element Method (FEM). The results reveal that the air velocity and power input have significant effects on the performance of FLHP. As the heat input and air velocity increase, total thermal resistance decreases.
Power Converter for Dual-Power PV-Grid Energy System Utilizing Cascaded Multilevel Inverter
Authors: Ibrahim Intan Rahayu , Omar Ahmad Maliki , Hussain Zakaria
Published: April 2014

The dual-power PV-grid system was introduced to manipulate the lower tariff rate at off-peak period and to reduce the capital installation cost of PV energy system. The power converter in the PV energy system is used to process solar energy captured by PV modules into usable electrical energy. In the dual-power PV-grid system, the power converter component is consists of a boost regulator to boost and regulate PV outputs to fixed voltage of 240V, 50Hz, a maximum power point tracker (MPPT) to derive maximum power from PV panels and a three operation modes of the battery converter to regulate charging current/discharging current under various PV output and load variation. In this project, a reduced switch and increased level of cascaded H-bridge multilevel inverter was introduced to convert the direct current (DC) output of the solar energy to alternating current (AC) signal to supply an AC load or to be integrated to the grid system. By adapting selective harmonic elimination (SHE) switching strategy, the inverter produces 21 levels of stepped sinusoidal output signal with resultant total harmonics distortion (THD) of 3.90%.
Monolithic Biosensor for Gene-Based Disease Detection
Authors: Hwan Wong How , Yusof Yusmeeraz
Published: April 2014

In this paper, charge-modulated field effect transistor based detection circuit is presented for the purpose of electrical detection of DNA hybridization. The readout circuit consists of a drain follower and a compensated differential amplifier. It is able to achieve a voltage gain of 56.94 dB in the frequency range up to 6.79 kHz using 0.18μm Silterra CMOS process. The compensation technique is used in the detection circuit in order to improve the phase margin to 52.66o. The proposed potentiometric biosensor eliminates the need for a reference electrode which can offer great potential for miniaturized sensor array that would enable a massive parallel detection of DNA assay.
Effect of Metal Doped-TiO2 on the Performance of Dye Solar Cells (DSCs)
Authors: Zaine Siti Nur Azella , Norani Muti Mohamed , Samsudin Adel Eskandar , Sahmer Ahmad Zahrin
Published: April 2014

Doping of TiO2 with metal or non-metal elements draws much attention in tailoring the properties of photoanode in Dye Solar Cells (DSCs). In this study, liquid impregnation method was implemented in synthesizing metal-doped TiO2 of Al, Fe, Ni and Zn in order to study the effect of doping of metals in TiO2 photoelectrode materials on the performance of integrated DSCs. The synthesized samples were then screen printed onto FTO glass, sensitized with N719 and assembled in sandwich layer with Pt counter electrode. The performance of integrated DSCs was verified using I-V characteristics under illumination of simulated AM 1.5 solar radiance. EIS characterization was done to further understand the electrochemical properties of metal-doped TiO2 photoelectrode of a DSC. The results show that doping with Al at concentration of 0.5 moles metal ion over 100 moles of Ti4+ ions can improve the overall performance efficiency of a DSC from 3.656% to 4.540%. However, Ni and Zn-doped TiO2 photoelectrode were found to improve the Voc whilst DSC with Al-doped TiO2 exhibits the highest Isc and the lowest Rdc resulting in the highest efficiency compared to other metal doped TiO2 DSCs. The doping could influence the electron transport in the photoelectrode materials and interface charge recombination between the photoelectrode materials and the redox electrolyte.
Characterization of Micro-Gap Electrodes Initial Pattern on Resist by Employing High Sensitive and Selective Chrome Mask
Authors: Haisu M. , Hashim Uda , Humayun Q.
Published: April 2014

The detection of most serious diseases at early stages is one of the challenging tasks for researchers of nanotechnology. Therefore the current research article is one of the attempts to fabricate highly sensitive and selective micro-gap electrodes at initial level; such micro-gap electrodes will be used in future for inserting biomolecule in between the gap spacing. To transfer the micro-gap design pattern to sample wafer accurately and preciously, micro-gap was initially designed by using AutoCAD software and the design was finally transferred to high sensitive and selective chrome mask. The article demonstrates experimentally an initial strategy for fabrication of micro-gap electrodes at resisting using conventional photolithography technique coupled with the wet etching process. The structure morphology was characterized using high power and scanning electron microscope namely (HPM and SEM).
Effect of Reflective Platinum Film on the Performance of Flexible Dye Solar Cell (DSC)
Authors: Sahmer Ahmad Zahrin , Norani Muti Mohamed
Published: April 2014

Robust and flexible dye solar cell (DSC) made up of nanocrystalline TiO2 encapsulated in polyethylene naphthalate (PEN) substrate will be able to fulfill the demand for indoor power applications as it has lower energy and manufacturing cost, produces electricity in low light conditions even under artificial light. The fabrication using PEN substrate has the advantage of scalability and compatible with the roll to roll manufacturing method. This paper reports the study on the effect of platinum film reflectance on the counter electrode to the DSC performance and efficiency. The reflective counter electrode uses the commercially available Pt/Ti PEN film with 100% reflectance properties. The transparent counter electrode with 20.9% reflectance is prepared using pre-treated indium doped tin oxide (ITO). The platinum film is sintered at 170°C followed by direct heat of 150°C to achieve a good bonding between the ITO and the deposited platinum film. Both cells uses TiO2 coated ITO PEN as the working electrode. The DSC test cell with reflective counter electrode increases the cell efficiency compared to the non-reflective counter electrode as there is a higher light spectrum response on the reflective DSC cell.
Characterization of Nanostructured Heterojunction Solar Cells of CdS/Cd2x(CuIn)1-xS2 Grown by Chemical Spray Pyrolysis
Authors: Al-Jumaili Hamid S. , Al-Rawi Mohammed Z. , Al-Douri Y.
Published: April 2014

A nanostructured heterojunction of CdS/Cd2x(CuIn)1-xS2 with x=0.2 was prepared by chemical spray pyrolysis on ITO/glass substrate at 350 °C. The X-ray diffraction pattern obtained from CdS/Cd2x(CuIn)1-xS2 solar cell confirmed the formation of Cd2x(CuIn)1-xS2 (CCIS), CuInS2, In2S3, and CdS phases, with crystallite size of 16 nm for CCIS and 26 nm for CdS films. The morphology of the film surface was obtained by AFM technique, which produced a greater grain size of 58.3 nm for CdS and 80 nm for CCIS surfaces. Optical absorbance analysis confirmed the composition-controlled electronic transition in the thin film, and the energy band gap was observed to red shift with the increase in the value of x. The electrical properties produced a P-type conductivity of CCIS with two activation energies. I–V characteristic in dark condition produced unsymmetrical heterojunctions, whereas abrupt-type heterojunctions were produced from the C–V curve. The solar energy conversion efficiencies achieved upon illumination of 100 mW/cm2 were 0.35%, 0.5%, 0.9%, and 1.28% for CCIS thicknesses of 610, 800, 910, and 1000 nm, respectively.
Efficiency Enhancement in Dye-Sensitized Solar Cell Using TiO2 /Ilmenite-Derived Nanofiber Composite as Working Electrode
Authors: Simpraditpan Athapon , Wirunmongkol Thanakorn , Pavasupree Sorapong , Pecharapa Wisanu
Published: April 2014

TiO2 nanocomposite films of calcined TiO2 nanofibers and commercial-grade TiO2 nanoparticles Degussa (P25) utilized as working electrode of dye-sensitized solar cells (DSSCs) are prepared by a doctor blade method. TiO2 nanofibers were synthesized from ilmenite mineral by hydrothermal process in combination with calcinations process. The prepared samples are characterized by XRD, XPS and TEM. The photoelectric conversion performance of the DSSC based on nanocomposite film electrode was compared to the device fabricated by pure P25 at the same film thickness. The result shows that as calcination temperature increases, the transformation of nanofibers to nanorods and nanoparticles were observed. The energy conversion efficiency (ƞ) of the device tends to with increasing calcined temperature. The greatest ƞ is 3.90% obtained from DSSC fabricated from nanocomposite film electrode of 5 wt.% nanofibers calcined at 800 oC for 2 h mixed with P25, indicating the significant enhancement in its performance by the incorporation of the nanofibers. This enhancement of DSSCs may correlate to high surface area, higher light scattering and light harvesting, low charge recombination and fast electron-transfer rate by nanofibers.