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PublicationPhotocatalytic degradation of phenol in a fluidized bed reactor utilizing immobilized TiO2 photocatalyst: Characterization and process studies( 2011)
;H.M.R. AkmalM. Abdul RahmanRemediation of hazardous materials in water has emerged as a top priority over the years. Organic pollutants in water are one of the major constituents in water pollution. Phenol is one of the organic pollutants which are commonly found in the effluent of industries such as petroleum refineries and petrochemicals. Conventional treatment techniques such as filtration and flocculation and carbon adsorption have limitations of their own. Thus, photocatalysis offers a possible alternative in treating wastewater effluent containing phenols. This study attempts to evaluate photocatalytic degradation of phenol in a fluidized bed reactor. Immobilized TiO2 supported onto quartz sand was used as the photocatalyst and characterized using SEM, EDX and XRD analysis. The performance of the supported photocatalyst is evaluated in different operating parameters such as photocatalyst loading and initial phenol concentration. -
PublicationUtilization of agricultural by-products for alpha-amylase production under solid state fermentation by bacillus subtilis( 2012)Khairiah Abd KarimThe production of alpha-amylase by Bacillus subtilis was investigated under different cultivation conditions on two different solid substrates as the support, i.e. oil palm empty fruit bunch (OPEFB) fibers and rice straw using solid state fermentation (SSF) process. Both solid substrates were first pre-treated using NaOH to remove lignin and silica and to break down the hemicellulose structures. The influences of incubation time, incubation temperature and the additional carbon and nitrogen sources on the production of alpha-amylase by B. subtilis were investigated. After 48 h of incubation, the highest enzyme activities were obtained at 39.9 U/g and 23.5 U/g for rice straw and OPEFB fibers, respectively. The optimum temperature for alpha-amylase production was observed at 45°C for the OPEFB fibers and 55°C for the rice straw. Among the defined carbohydrates, the addition of glucose (0.02 g/g dry substrate) has significantly improved the production of alpha-amylase. Similar effect was observed when yeast extract (0.01 g/g dry substrate) was supplemented as the additional nitrogen source. Rice straw appeared to be the best solid substrate in producing alpha-amylase (276 U/g) in SSF under these optimum cultivation conditions
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PublicationVirtual searching of dummy template for sinensetin based on 2D molecular similarity using chemdb tool( 2012)
;Iqmal Tahir ;Mohd Noor Ahmad ;AKM Shafiqul IslamDachyar ArbainSinensetin-like molecules have been searched virtually to find a dummy template for Molecular Imprinted Polymer (MIP) synthesis. The aim of this study is to find a novel adsorbent for Solid Phase Extraction (SPE) of sinensetin based on tailored method using dummy template. Virtual searching was done using ChemDB online chemical database containing 5 million commercially available chemicals. Sinensetin as target was converted into SMILES code then it was run with threshold of molecular similarity score of 0.5. There were 90 chemical structures given as the output mainly flavone analogue, three flavonols and several non-flavonoid compounds. The suggested results are three dummy templates that derived from luteolin (flavon) or quercetin (flavonol) with slight alteration by methoxylation process. -
PublicationEffect of steam pretreatment on oil palm empty fruit bunch for the production of sugars( 2012-01)
;Umi Kalsom Md Shah ;Huzairi Zainudin ;Suraini Abd-Aziz ;Siti Mazlina Mustapa Kamal ;Yoshihito ShiraiMohd Ali HassanLignocellulose into fuel ethanol is the most feasible conversion route strategy in terms of sustainability. Oil palm empty fruit bunch (EFB) generated from palm oil production is a huge source of cellulosic material and represents a cheap renewable feedstock which awaits further commercial exploitation. The purpose of this study was to investigate the feasibility of using steam at 0.28 MPa and 140 °C generated from the palm oil mill boiler as a pretreatment to enhance the digestibility of EFB for sugars production. The effects of steam pretreatment or autohydrolysis on chemical composition changes, polysaccharide conversion, sugar production and morphology alterations of four different types of EFB namely fresh EFB (EFB1), sterilized EFB (EFB2), shredded EFB (EFB3) and ground EFB (EFB4) were evaluated. In this study, the effects of steam pretreatment showed major alterations in the morphology of EFB as observed under the scanning electron microscope. Steam pretreated EFB2 was found to have the highest total conversion of 30% to sugars with 209 g kg -1 EFB. This production was 10.5 fold higher than for EFB1 and 1.6 fold and 1.7 fold higher than EFB3 and EFB4, respectively. The results suggested that pretreatment of EFB by autohydrolysis using steam from the mill boiler could be considered as being a suitable pretreatment process for the production of sugars. These sugars can be utilized as potential substrates for the production of various products such as fuel ethanol. -
PublicationFly Ash porous material using geopolymerization process for high temperature exposure( 2012-04-10)
;Mohamed Bnhussain ;Che Mohd Ruzaidi GhazaliMohd Izzat AhmadThis paper presents the results of a study on the effect of temperature on geopolymers manufactured using pozzolanic materials (fly ash). In this paper, we report on our investigation of the performance of porous geopolymers made with fly ash after exposure to temperatures from 600 °C up to 1000 °C. The research methodology consisted of pozzolanic materials (fly ash) synthesized with a mixture of sodium hydroxide and sodium silicate solution as an alkaline activator. Foaming agent solution was added to geopolymer paste. The geopolymer paste samples were cured at 60 °C for one day and the geopolymers samples were sintered from 600 °C to 1000 °C to evaluate strength loss due to thermal damage. We also studied their phase formation and microstructure. The heated geopolymers samples were tested by compressive strength after three days. The results showed that the porous geopolymers exhibited strength increases after temperature exposure. -
PublicationUtilization of agricultural by-products for alpha-amylase production under solid state fermentation by Bacillus subtilis( 2012-08-18)Khairiah Abd KarimThe production of alpha-amylase by Bacillus subtilis was investigated under different cultivation conditions on two different solid substrates as the support, i.e. oil palm empty fruit bunch (OPEFB) fibers and rice straw using solid state fermentation (SSF) process. Both solid substrates were first pre-treated using NaOH to remove lignin and silica and to break down the hemicellulose structures. The influences of incubation time, incubation temperature and the additional carbon and nitrogen sources on the production of alpha-amylase by B. subtilis were investigated. After 48 h of incubation, the highest enzyme activities were obtained at 39.9 U/g and 23.5 U/g for rice straw and OPEFB fibers, respectively. The optimum temperature for alpha-amylase production was observed at 45°C for the OPEFB fibers and 55°C for the rice straw. Among the defined carbohydrates, the addition of glucose (0.02 g/g dry substrate) has significantly improved the production of alpha-amylase. Similar effect was observed when yeast extract (0.01 g/g dry substrate) was supplemented as the additional nitrogen source. Rice straw appeared to be the best solid substrate in producing alpha-amylase (276 U/g) in SSF under these optimum cultivation conditions.
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PublicationMechanical and microstructural evaluations of lightweight aggregate geopolymer concrete before and after exposed to elevated temperatures( 2013)
;Omar AbdulkareemMohammed BinhussainThis paper presents the mechanical and microstructural characteristics of a lightweight aggregate geopolymer concrete (LWAGC) synthesized by the alkali-activation of a fly ash source (FA) before and after being exposed to elevated temperatures, ranging from 100 to 800 °C. The results show that the LWAGC unexposed to the elevated temperatures possesses a good strength-to-weight ratio compared with other LWAGCs available in the published literature. The unexposed LWAGC also shows an excellent strength development versus aging times, up to 365 days. For the exposed LWAGC to the elevated temperatures of 100 to 800 °C, the results illustrate that the concretes gain compressive strength after being exposed to elevated temperatures of 100, 200 and 300 °C. Afterward, the strength of the LWAGC started to deteriorate and decrease after being exposed to elevated temperatures of 400 °C, and up to 800 °C. Based on the mechanical strength results of the exposed LWAGCs to elevated temperatures of 100 °C to 800 °C, the relationship between the exposure temperature and the obtained residual compressive strength is statistically analyzed and achieved. In addition, the microstructure investigation of the unexposed LWAGC shows a good bonding between aggregate and mortar at the interface transition zone (ITZ). However, this bonding is subjected to deterioration as the LWAGC is exposed to elevated temperatures of 400, 600 and 800 °C by increasing the microcrack content and swelling of the unreacted silicates. -
PublicationThe effect of various waste materials' contents on the attenuation level of anti-radiation shielding concrete( 2013)
;Ali Azeez ;Kahtan Mohammed ;Sandu, Andrei VictorSamples of concrete contain various waste materials, such as iron particulates, steel balls of used ball bearings and slags from steel industry were assessed for their anti-radiation attenuation coefficient properties. The attenuation measurements were performed using gamma spectrometer of NaI (Tl) detector. The utilized radiation sources comprised 137Cs and 60Co radioactive elements with photon energies of 0.662 MeV for 137Cs and two energy levels of 1.17 and 1.33 MeV for the 60Co. Likewise the mean free paths for the tested samples were obtained. The aim of this work is to investigate the effect of the waste loading rates and the particulate dispersive manner within the concrete matrix on the attenuation coefficients. The maximum linear attenuation coefficient (μ) was attained for concrete incorporates iron filling wastes of 30 wt %. They were of 1.12 ± 1.31×10-3 for 137Cs and 0.92 ± 1.57 × 10-3 for 60Co. Substantial improvement in attenuation performance by 20%-25% was achieved for concrete samples incorporate iron fillings as opposed to that of steel ball samples at different (5%-30%) loading rates. The steel balls and the steel slags gave much inferior values. The microstructure, concrete-metal composite density, the homogeneity and particulate dispersion were examined and evaluated using different metallographic, microscopic and measurement facilities. -
PublicationCopper-filled electrically conductive adhesives with enhanced shear strength( 2014)Hiroshi NishikawaIn this study, the effects of diethyl carbitol (diluent) and tertiary amines on the electrical, mechanical, and rheological properties of the Cu-filled polyurethane-based electrically conductive adhesives (ECAs) were investigated. Significant difference could be observed in the electrical resistivity and shear strength of ECA prepared with different amount of diethyl carbitol. Reduced electrical resistivity was found in ECAs prepared with addition of tertiary amines, but no obvious change was observed in the shear strength of the ECA joint. Rheological property of the ECA paste was investigated in order to understand the correlation of the viscosity of ECA paste and electrical resistivity and shear strength of ECA joint. Results revealed that decrease in viscosity of the ECA paste reduced electrical resistivity and enhanced shear strength of ECA joint. A Cu-filled polyurethane-based ECA with considerably low electrical resistivity at the magnitude order range of 10-3 Ωcm, and significantly high shear strength (above 17 MPa) could be achieved.
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PublicationPreparation of biodegradable polymeric nanoparticles for pharmaceutical applications using glass capillary microfluidics( 2015)
;Goran T. VladisavljevićZoltan K. NagyThe aim of this study was to develop a new microfluidic approach for the preparation of nanoparticles with tuneable sizes based on micromixing/direct nanoprecipitation in a coaxial assembly of tapered-end glass capillaries. The organic phase was 1 wt% poly(ε-caprolactone) (PCL) or poly(dl-lactic acid) (PLA) in tetrahydrofuran and the antisolvent was Milli-Q water. The size of nanoparticles was precisely controlled over a range of 190–650 nm by controlling phase flow rates, orifice size and flow configuration (two- phase co-flow or counter-current flow focusing). Smaller particles were produced in a flow focusing device, because the organic phase stream was significantly narrower than the orifice and remained narrow for a longer distance downstream of the orifice. The mean size of PCL particles produced in a flow focusing device with an orifice size of 200 μm, an organic phase flow rate of 1.7 mL h 1 and an aqueous-to-organic flow rate ratio of 10 was below 200 nm. The size of nanoparticles decreased with decreasing the orifice size and increasing the aqueous-to-organic phase flow rate ratio. Due to higher affinity for water and amorphous structure, PLA nanoparticles were smaller and exhibited a smoother surface and more rounded hape than PCL particles. -
PublicationRole of metals content in spinach in enhancing the conductivity and optical band gap of chitosan films( 2015)
;Irwana Nainggolan ;Devi Shantini ;Tulus Ikhsan NasutionBlend of chitosan and spinach extract has been successfully prepared using acetic acid as a solvent medium to produce chitosan-spinach films. The conductivity measurements showed that chitosan-spinach films for all ratios of 95 : 5, 90 : 10, 85 : 15, and 80 : 20 had better conductivity than the chitosan film. The optical band gap reduced with the addition of the spinach extract into chitosan. Chitosan-spinach film with the ratio of 85 : 15 gave the best electrical properties in this work with the conductivity of 3.41 × 10−6 S/m and optical band gap of 2.839 eV. SEM-EDX spectra showed the existence of potassium, phosphorus, sulphur, iron, and oxygen in chitosan-spinach films. AFM image showed that the surface morphology of the films became rougher as the spinach incorporated into chitosan. The minerals which exist in spinach extract play a role in enhancing electrical properties of chitosan film. -
PublicationEffect of hydrochloric acid concentration on morphology of polyaniline nanofibers synthesized by rapid mixing polymerization( 2015)
;Zulkhairi Zakaria ;Nurul F. A. Halim ;Mubaraq H. V. Schleusingen ;A. K. M. Shafiqul IslamMohd N. AhmadPolyaniline (PANI) nanofibers with diameters ranging from 60 nm to 190 nm were successfully synthesized by rapid mixing polymerization method at room temperature. The effects of synthesis conditions such as concentration of hydrochloric acid (HCl), ammonium persulfate (APS), and aniline monomer (Ani) on the morphology of PANI nanofibers were investigated using scanning electron microscopy (SEM). FTIR and UV-Vis analysis were performed to characterize the PANI nanofibers. The effect of polymerization time and electrical properties of PANI nanofibers was also discussed. A rapid mixing polymerization method is found to be advantageous in producing bulk quantities of nanofibers. -
PublicationEffect of solids-to-liquids, Na2SiO3-To-NaOH and curing temperature on the palm oil boiler ash (Si + Ca) geopolymerisation system( 2015)Andrei Victor SanduThis paper investigates the effect of the solids-to-liquids (S/L) and Na2SiO3/NaOH ratios on the production of palm oil boiler ash (POBA) based geopolymer. Sodium silicate and sodium hydroxide (NaOH) solution were used as alkaline activator with a NaOH concentration of 14 M. The geopolymer samples were prepared with different S/L ratios (0.5, 1.0, 1.25, 1.5, and 1.75) and Na2SiO3/NaOH ratios (0.5, 1.0, 1.5, 2.0, 2.5, and 3.0). The main evaluation techniques in this study were compressive strength, X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscope (SEM). The results showed that the maximum compressive strength (11.9 MPa) was obtained at a S/L ratio and Na2SiO3/NaOH ratio of 1.5 and 2.5 at seven days of testing.
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PublicationEffect of Ni on the formation and growth of primary Cu6Sn5 intermetallics in Sn-0.7 wt.%Cu solder pastes on Cu substrates during the soldering process( 2015)
;M.A.A. Mohd Salleh ;S.D. McDonald ;C.M. Gourlay ;S.A. Belyakov ;H. YasudaK. NogitaThis paper investigates the effect of 0.05 wt.% Ni on the formation and growth of primary Cu6Sn5 in Sn-0.7 wt.%Cu solder paste soldered on a Cu substrate, using a real-time synchrotron imaging technique. It was found that small additions of Ni significantly alter the formation and growth of the primary Cu6Sn5 intermetallics, making them small. In contrast, without Ni, primary Cu6Sn5 intermetallics tend to continue growth throughout solidification and end up much larger and coarser. The primary effect of the Ni addition appears to be in promoting the nucleation of a larger amount of small Cu6Sn5. The results provide direct evidence of the sequence of events in the reaction of Nicontaining Sn-0.7 wt.%Cu solder paste with a Cu substrate, and in particular the formation and growth of the primary Cu6Sn5 intermetallic -
PublicationEffect of differences Methanol concentration and extraction time on the antioxidant capacity, phenolics content and bioactive constituents of Orthosiphon Stamineus extracts( 2016)
;Noorhaslina Hashim ;Abdul Razak Shaari ;Awang Soh Mamat -
PublicationEffect of crumb rubber on compressive strength of fly ash based geopolymer concrete( 2016)
;Che Mohd Ruzaidi Ghazali ;Andrei Victor SanduThis study explores the effect of different percentage of crumb rubber on compressive strength of fly ash based geopolymer concrete. This research attempted to produce rubberized geopolymer concrete as an environmentally friendly, lightweight and durable product. Crumb rubber with ranged size from 73 µm to 375 µm was used in order to replace fine aggregates in geopolymer concrete. The replacements of crumb rubber were 0%, 5%, 10%, 15% and 20% in the fly ash based geopolymer concrete. The ratio of fly ash to alkaline activator was 2.5 and the ratio of Na2SiO3 to NaOH was fixed at 2.0. After the curing process, the strengths of the samples were tested on days 7 and 28. The results show that there is a reduction in all compressive strength for crumb rubber mixture, but still higher than normal rubberized concrete. Rubberized geopolymer concrete is a suitable solution in some non structural applications. -
PublicationBiotechnological processes in microbial amylase production( 2017)
;Subash C. B. Gopinath ;Periasamy Anbu ;M. K. Md Arshad ;Thangavel LakshmipriyaSuresh V. ChinniAmylase is an important and indispensable enzyme that plays a pivotal role in the field of biotechnology. It is produced mainly from microbial sources and is used in many industries. Industrial sectors with top-down and bottom-up approaches are currently focusing on improving microbial amylase production levels by implementing bioengineering technologies. The further support of energy consumption studies, such as those on thermodynamics, pinch technology, and environment-friendly technologies, has hastened the large-scale production of the enzyme. Herein, the importance of microbial (bacteria and fungi) amylase is discussed along with its production methods from the laboratory to industrial scales. -
PublicationDemonstration of chemistry at a point through restructuring and catalytic activation at anchored nanoparticles( 2017)
;Dragos Neagu ;Evangelos I. Papaioannou ;David N. Miller ;Billy J. Murdoch ;Hervé Ménard ;Ahmed Umar ;Anders J. Barlow ;Peter J. Cumpson ;John T. S. IrvineIan S. MetcalfeMetal nanoparticles prepared by exsolution at the surface of perovskite oxides have been recently shown to enable new dimensions in catalysis and energy conversion and storage technologies owing to their socketed, well-anchored structure. Here we show that contrary to general belief, exsolved particles do not necessarily re-dissolve back into the underlying perovskite upon oxidation. Instead, they may remain pinned to their initial locations, allowing one to subject them to further chemical transformations to alter their composition, structure and functionality dramatically, while preserving their initial spatial arrangement. We refer to this concept as chemistry at a point and illustrate it by tracking individual nanoparticles throughout various chemical transformations. We demonstrate its remarkable practical utility by preparing a nanostructured earth abundant metal catalyst which rivals platinum on a weight basis over hundreds of hours of operation. Our concept enables the design of compositionally diverse confined oxide particles with superior stability and catalytic reactivity -
PublicationSpin-polarized second harmonic generation from the antiferromagnetic CaCoSO single crystal( 2017)Reshak A.H.The spin-polarized second harmonic generation (SHG) of the recently synthesized CaCoSO single crystal is performed based on the calculated electronic band structure. The calculation reveals that the spin-up (↑) channel of CaCoSO possesses a direct energy gap (Γv-Γc) of about 2.187 eV, 1.187 eV (Kv-Kc) for the spin-down (↓) channel and an indirect gap (Γv-Kc) of about 0.4 eV for the spin-polarized CaCoSO single crystal. The linear optical properties obtained reveal that the recently synthesized crystal exhibits considerable anisotropy with negative uniaxial anisotropy and birefringence favor to enhance the SHG. We have calculated the three non-zero tensor components of the SHG and found the "Equation missing" is the dominat component, one with a large SHG of about (d < (↓)"Equation missing" < spin-polarized "Equation missing" are related to the values of the energy gap of (↑) 2.187 eV> (↓) 1.187 eV> spin-polarized gap 0.4 eV; therefore, a smaller energy gap gives better SHG performance. Furthermore, the microscopic first hyperpolarizability,β, is calculated.
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PublicationExtraction of Spear Grass (Imperata Cylindrica) as Pro-Oxidant In polymer blends( 2018)
;N. A. Abdul Halim ;K.F. Kasim ;S.T. Sam ;H.I. ZulhaimiPackaging material such as plastic bags is one of the main factors that contribute to the environmental pollution due to slow degradation. The usage of metal oxide as pro-oxidant has been proven to accelerate the degradation of these materials, but the excessive usage of this pro-oxidant will be harmful to the human body. Therefore, in this research, spear grass is investigated to be used as natural based pro-oxidant that can increase the degradation rate of the polymers. In terms of that, spear grass is extracted by using pressurized hot water extraction (PHWE) to obtain the metal element such as zinc (Zn) and ferum (Fe). PHWE is using water as a solvent which is highly favourable due to non-toxicity and non-flammable characteristics that make it easy to handle. Box-Behnken design is used to optimize the temperature, extraction time, and sample-to-solvent ratio to get the maximum amount of Zn and Fe concentration from the extracted spear grass. As a conclusion, the leaf of spear grass contributed the highest amount of Zn and Fe concentration. The highest amount of Zn and Fe concentration is achieved at 150 °C, 20 minutes, and 3 g of sample to 45 ml of water.