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Ahmad M.Z.,RMIT University | Ahmad M.Z.,Mechanisation and Automation Research Center | Chang J.,Queensland University of Technology | Ahmad M.S.,University Malaysia Perlis | And 2 more authors.
Sensors and Actuators, B: Chemical | Year: 2013

Zinc oxide (ZnO) nanopyramids were synthesized by a one-pot route in a non-aqueous and surfactant-free environment. The synthesized metal oxide was characterized using SEM, XRD, and TEM to investigate the surface morphology and crystallographic phase of the nanostructures. It was observed that the ZnO nanopyramids were of uniform size and symmetrical, with a hexagonal base and height of ∼100 nm. Gas sensing characterization of the ZnO nanopyramids when deposited as thin-film onto conductometric transducers were performed towards NOx and C2H5OH vapor of different concentrations over a temperature range of 22-350 °C. It was observed that the sensors responded towards NO2 (10 ppm) and C2H 5OH (250 ppm) analytes best at temperatures of 200 and 260 °C with a sensor response of 14.5 and 5.72, respectively. The sensors showed satisfactory sensitivity, repeatability as well as fast response and recovery towards both the oxidizing and the reducing analyte. The good performance was attributed to the low amount of organic impurities, large surface-to-volume ratio and high crystallinity of the solvothermally synthesized ZnO nanopyramids. © 2012 Elsevier B.V. All rights reserved.

Ahmad M.Z.,RMIT University | Ahmad M.Z.,Mechanisation and Automation Research Center | Kang J.H.,Incheon National University | Sadek A.Z.,RMIT University | And 3 more authors.
Procedia Engineering | Year: 2012

WO3 nanorod based thin films were deposited via pulsed laser deposition onto conductometric transducers employing the shortest wavelength (193 nm) ArF excimer laser. Micro-characterization techniques such as SEM and XRD were employed to study surface morphology and crystal structure. It was observed that the fabricated films showed nanocolumnar features perpendicular to the surface. Gas sensing characterizations of the developed sensors were tested towards hydrogen and ethanol at temperature between room and 400 °C. The sensor exhibited high response towards H2 and ethanol at operating temperatures of 170 and 400 °C, respectively. © 2012 The Authors. Published by Elsevier Ltd.

Yaacob M.H.,University Putra Malaysia | Yaacob M.H.,RMIT University | Ahmad M.Z.,RMIT University | Ahmad M.Z.,Mechanisation and Automation Research Center | And 5 more authors.
Sensors and Actuators, B: Chemical | Year: 2013

The gasochromic response of WO3 nanostructured films coated with a catalytic Pt or Pd layer on different transparent substrates upon exposure to H2 gas was investigated. WO3 nanostructured films with 500 nm thickness were coated with a 25 thick Pt or Pd layer. The films were prepared on quartz, glass, indium-doped tin oxide (ITO) and fluorine-doped tin oxide (FTO) conductive glass. The nanostructured WO3 was deposited by RF magnetron sputtering, and the Pt or Pd layer was deposited by DC sputtering. Characterization of the film revealed that the WO3 was deposited as nanoscale grains of varied size depending on the substrate. WO3 grains on quartz and glass were 30-40 nm in size. WO3 grain sizes on ITO and FTO were 40-60 nm and 300-500 nm, respectively. The WO3 films were observed to show strong gasochromic response, with absorbance changes measured in the Vis-NIR (500-1100 nm) range. The cumulative absorbance response towards H2 is the highest and more stable for Pd/WO3 films on quartz, glass and ITO, compared to the FTO substrate. The gasochromic effect was also stronger in Pd/WO3 films compared to Pt/WO3 films. © 2012 Elsevier B.V. All rights reserved.

Ahmad M.Z.,RMIT University | Ahmad M.Z.,Mechanisation and Automation Research Center | Sadek A.Z.,RMIT University | Yaacob M.H.,University Putra Malaysia | And 4 more authors.
Sensors and Actuators, B: Chemical | Year: 2013

Nanostructured gold/tungsten trioxide (Au/WO3) thin films based gasochromic sensors have been developed and investigated towards hydrogen (H2) at low concentrations. Using a novel wet chemical method, atomically precise gold (Au) nanoclusters were deposited onto tungsten trioxide (WO3) films supported on a quartz substrate. The Au/WO3 based sensors exhibited change in gasochromic properties upon exposure to H 2 in the visible-NIR (800-1000 nm) range. The total absorbance in this range increased by approximately 2.5%, when exposed to H2 gas (0.06%) balanced in synthetic air at an operating temperature of 200°C. The micro-structural properties of the films were studied via energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). EDX analysis of the Au/WO3 films on quartz substrates shows the presence of strong tungsten (W) and oxygen (O) peaks, which indicates that the films are mainly consisted of WO3. TEM investigation showed that the synthesised Au nanoparticles have average diameters of 2-5 nm after deposition. SEM investigations revealed agglomeration of the Au phosphine [Au9(PPh3)8(NO 3)3] clusters to form nanoparticles on top of WO 3 layer. At optimum operating temperature (200°C), fast response (<2 min) and recovery in conjunction with a stable baseline occurs. © 2012 Elsevier B.V. All rights reserved.

Ou J.Z.,RMIT University | Ahmad M.Z.,RMIT University | Ahmad M.Z.,Mechanisation and Automation Research Center | Latham K.,RMIT University | And 3 more authors.
Procedia Engineering | Year: 2011

Nanosturctured WO 3 films were synthesized via anodization at elevated temperature. Nitric acid (HNO 3) and sulfuric acid (H 2SO 4) were employed for the first time. Different nanostructured morphologies were observed. The novel conductometric H 2 gas sensor has been developed based on these WO 3 films. The sensor with anodized WO 3 film in HNO 3 exhibited high sensitivity towards H 2 as low as 0.06% at relatively low operating temperature (120 °C). © 2011 Published by Elsevier Ltd.

Ahmad M.Z.,Mechanisation and Automation Research Center | Ahmad M.Z.,RMIT University | Sadek A.Z.,RMIT University | Ou J.Z.,RMIT University | And 3 more authors.
Materials Chemistry and Physics | Year: 2013

A simple technique to fabricate nanostructured WO3 thin films onto conductomeric transducers has been employed for ethanol sensing application. Initially, pure tungsten (W) thin films were deposited onto the substrate employing RF sputterer and followed by an etching process. Three types of etching agent were used: nitric (HNO3), sulphuric (H 2SO4), and phosphoric (H3PO4) acid. It was found that the surface morphology and crystallinity of the WO3 films were heavily dependant to the etchants employed during the fabrication process. The developed sensors were tested towards ethanol vapor of different concentrations (10-200 ppm) at temperatures between room and 450 C. The sensors showed stable and reproducible response at optimum operating temperatures. High sensor response towards vaporized ethanol as well as fast τres and τrec was observed during the "adsorption" and "desorption" interval. The recorded maximum response for these devices when exposed towards 100 ppm ethanol was measured to be 8 (Ro = 4.6 kΩ), 5.8 (Ro = 22.5 GΩ), and 5 (Ro = 0.29 MΩ) for HNO3, H3PO4, and H 2SO4, respectively. The optimum operating temperatures were determined to be 400, 300-380, and 360 C for the sensors developed using HNO3, H3PO4, and H2SO4, respectively. © 2013 Elsevier B.V. All rights reserved.

Hanafi M.M.,University Putra Malaysia | Shahidullah S.M.,University Putra Malaysia | Niazuddin M.,University Putra Malaysia | Abd Aziz Z.,University Putra Malaysia | Mohammud C.H.,Mechanisation and Automation Research Center
Journal of Food, Agriculture and Environment | Year: 2010

The BRIS (Beach Ridges Interspersed with Swales) soils are the sandy marine deposits at the east coast of Peninsular Malaysia. The area is less suitable for usual field crops. Pineapple (Ananas comosus) may be introduced in the area for commercial cultivation. An experiment was conducted in the glass house condition of UPM. Pineapple plants were nurtured in the lysimeters, filled with BRIS 228177839soil, to assess the water requirements at different growth stages. Highest requirement of irrigation water was found 2.43 mm/day in initial stage (1). Subsequent development stage (2), midstage (3) and ripening stage (4) required smaller amount of irrigation water (approximately 1.55 mm/day). The daily average evapotranspiration (ETc) was 0.83 mm/day in Stage 1, followed by 0.73 mm/day in Stage 2. The lowest ETc was found 0.65 mm/day in Stage 3. The estimated crop coefficient (Kc) was found maximum 0.51 in initial stage. The Kc values showed a continuous decreasing trend up harvesting time. The second highest Kc value was 0.37 in development stage followed by 0.33 in mid-stage and minimum 0.30 during ripening stage.

Hanaf M.M.,University Putra Malaysia | Shahidullah S.M.,University Putra Malaysia | Niazuddin M.,University Putra Malaysia | Abd Aziz Z.,University Putra Malaysia | Mohammud C.H.,Mechanisation and Automation Research Center
International Journal of Agriculture and Biology | Year: 2010

An experiment was conducted to determine the response of four sea water treatments on an improved pineapple genotype "N-36" grown in Beach Ridges Interspersed with Swales (BRIS) soil. Sea water treatments were prepared by substitution of K with Na ions i.e., 0% (in control), 15%, 30% and 60% of required K doses were replaced by Na ions from sea water. Treatment effects were non-significant up to 30% sodium replacement from sea water. Na replacement (60%) showed significant impact on different growth parameters at different stages (8-10 months after planting). However, the fruit yield, the final target of crop harvest was not adversely affected at significance level. Therefore, sea water irrigation can easily fulfil 60% dose of potassium fertilizer by sodium ions for the production of pineapple in BRIS soil. © 2010 Friends Science Publishers.

Yee P.M.,University Putra Malaysia | Shamsudin R.,University Putra Malaysia | Hamzah A.,Mechanisation and Automation Research Center | Endan J.,University Putra Malaysia
American Journal of Food Technology | Year: 2011

A pineapple rolled tart machine is required in the manufacturing of pineapple rolled tart. In this research, a machine that would reduce processing time and operating cost and that would be affordable for small-scale industries was designed. The machine was tested at different screw rotating speeds and dough formulations. The rolled tart throughput rates were significantly increased (p<0.05) with screw rotating speeds and butter percentages of dough. However, it was significantly decreased (p<0.01) with sugar and corn flour percentages. The hardness of baked tart and the hardness and stickiness of unbaked tarts were not significantly different between various screw rotating speeds and manual method. It was found that the rolled tart produced by this machine was acceptable in texture and mouth feel. The maximum and minimum rates for the standard dough formula were 4320 and 720 pieces h-1. © 2011 Academic Journals Inc.

Lee S.Y.,Mechanisation and Automation Research Center
Pertanika Journal of Science and Technology | Year: 2012

Tapioca starch, poly(lactic acid) and Cloisite 10A nanocomposite foams were prepared by twin screw extrusion. Residence time distribution (RTD) in an extruder is a useful means of determining optimal processing conditions for mixing, cooking and shearing reactions during the process. RTD was obtained by inputting a pulse-like stimulus and measuring its profile at the exit or other point in the extruder. During processing, after the steady state had been reached, a fixed amount of tracer was instantaneously fed into the extruder and its concentration was measured from the samples collected at fixed time intervals in the extruder exit. The tracer concentration was the value of the redness, a* was used as a measure of red colour intensity of the concentration of tracer in the extrudate. Meanwhile, the effects of two screw configurations (compression and mixing screws) and two barrel temperatures (150 and 160 oC) on RTD of nanocomposite foams were also studied. The influences of screw configurations and barrel temperatures on RTD were analyzed using the mean residence time (MRT) and variance. Screw configurations and temperatures had significant effects (P<0.05) on MTR. Mixing screws and lower temperature resulted in higher MRT and variance of RTD. © Universiti Putra Malaysia Press.

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