Wan Saffiey Wan Abdullah

Facile Synthesis of Calcium Borate Nanoparticles and the Annealing Effect on Their Structure and Size

Calcium borate nanoparticles have been synthesized by a thermal treatment method via facile co-precipitation. Differences of annealing temperature and annealing time and their effects on crystal structure, particle size, size distribution and thermal stability of nanoparticles were investigated. The formation of calcium borate compound was characterized by X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and Thermogravimetry (TGA). The XRD patterns revealed that the co-precipitated samples annealed at 700 °C for 3 h annealing time formed an amorphous structure and the transformation into a crystalline structure only occurred after 5 h annealing time. It was found that the samples annealed at 900 °C are mostly metaborate (CaB2O4) nanoparticles and tetraborate (CaB4O7) nanoparticles only observed at 970 °C, which was confirmed by FTIR. The TEM images indicated that with increasing the annealing time and temperature, the average particle size increases. TGA analysis confirmed the thermal stability of the annealed samples at higher temperatures.

Analyzing and sense making of human factors in the Malaysian radiation and nuclear emergency planning framework

The evolution of current Radiation and Nuclear Emergency Planning Framework (RANEPF) simulator emphasizes on the human factors to be analyzed and interpreted according to the stakeholder’s tacit and explicit knowledge. These human factor criteria are analyzed and interpreted according to the “sense making theory” and Disaster Emergency Response Management Information System (DERMIS) design premises. These criteria are corroborated by the statistical criteria. In recent findings, there were no differences of distributions among the stakeholders according to gender and organizational expertise. These criteria are incrementally accepted and agreed the research elements indicated in the respective emergency planning frameworks and simulator (i.e. 78.18 to 84.32, p-value <0.05). This paper suggested these human factors criteria in the associated analyses and theoretical perspectives to be further acomodated in the future simulator development. This development is in conjunction with the proposed hypothesis building of the process factors and responses diagram. We proposed that future work which implies the additional functionality of the simulator, as strategized, condensed and concise, comprehensive public disaster preparedness and intervention guidelines, to be a useful and efficient computer simulation.

XRD and photoluminescence properties of CaSo4: Dy phosphor synthesized by new Co-Precipitation method

This paper presents the luminescence properties of dysprosium (Dy) doped calcium sulfate (CaSO4) phosphor material produced by co-precipitation technique with 0.1 - 0.5 mol% concentration of dopant. The crystallinity of the produced powder was studied using x-ray powder diffraction (XRD). The XRD spectrum shows high purity anhydrite CaSO4 phosphor material produced. The average crystallite size of 74 nm with orthorhombic crystal system was obtained. The luminescence behavior of produced CaSO4: Dy was studied using a photoluminescence (PL) spectrometer. The excitation and emission spectrum peaks associated with defects and vacancies of the phosphor material at claimed crystalline phase. The mixed peaks of excitation and emission that corresponds to micro and nano sized particle was shown for the produced powders. These properties show that the produced powders have wide range of luminescence detection with many electron traps ready for thermoluminescence (TL) information storage.

Thermoluminescence (TL) properties and x-ray diffraction (XRD) analysis of high purity CaSO4:Dy TL material

This paper presents the characterization and TL properties of dysprosium (Dy) doped calcium sulfate (CaSO4) TL material produced by co-precipitation technique with 0.5mol% concentration of dopant. The morphology of the produced TL material was studied using scanning electron microscope (SEM) and the micrograph shows that rectangular parallelepiped shaped crystal with the average of 150 μm in length were produced. The crystallinity of the produced powder was studied using x-ray powder diffraction (XRD). The XRD spectra show that the TL material produced is high purity anhydrite CaSO4 with average crystallite size of 74 nm with orthorhombic crystal system. The TL behavior of produced CaSO4:Dy was studied using a TLD reader after exposure to gamma ray by Co60 source with the doses of 1,5 and 10 Gy. The glow curve shows linear response with glow peak around 230°C which is desired development in the field of radiation dosimetry.

Thermoluminescence Properties of Nanostructured Calcium Borate as a Sensitive Radiation Dosimeter for High Radiation Doses

The crystalline calcium tetraborate (CaB4O7) nanoparticles were synthesized using a combination of facile co-precipitation and thermal treatment. The synthesized phosphor nanoparticles were found to possess a monoclinic nanostructure of particle size of about 8 nm. The thermoluminescence (TL) glow curve of the nanoparticles shows a single peak centred at about 150°C. The TL nanophosphor revealed an excellent dosimetric response with a respectable linearity in the dose range of 0.05 to 1000 Gy, which is wider than its counterparts prepared by non nanosynthesis methods. They exhibited good luminescence efficiency and wide range linearity, suggesting the present phosphor nanoparticles may be considered as a suitable candidate for the dosimetric applications.

Synthesis, characterisation and dosimetric evaluation of MgB4O7 glass as thermoluminescent dosimeter

ABSTRACT This study presumably reports the dosimetric properties of MgB4O7 glass system. A series of MgB4O7 glass samples with nominal compositions XMgO-(100-X) B2O3, with X = 35, 40 and 45 mol% was successfully synthesied using conventional melt quenching method. The presence of broad humps and absence of any sharp peak in typical X-ray diffraction patterns confirm the amorphous nature of the synthesised glass samples. Good glass forming ability, 0.55, of the mixture resulting in a glass with excellent glass stability, 1.4, was observed. Thermoluminescence glow curve was observed to be simple with a single well defined dosimetric peak around 200°C. The dose response was found to be linear from 6 µGy to 0.5 kGy when irradiated to Cs-137 gamma rays. Considerably satisfying thermoluminescent (TL) characteristics suggests that the MgB4O7 glass could be recommended as a TL dosimeter.

Detection of irradiated spices using photo-stimulated luminescence technique (PSL)

Photo-stimulated luminescence (PSL) technique was applied to detect irradiated black pepper (Piper nigrum), cinnamon (Cinnamomum verum) and turmeric (Curcuma longa) after dark storage for 1 day, 3 and 6 months. Using screening and calibrated PSL, all samples were correctly discriminated between non-irradiated and spices irradiated with doses 1, 5 and 10 kGy. The PSL photon counts (PCs) of irradiated spices increased with increasing dose, with turmeric showing highest sensitivity index to irradiation compared to black pepper and cinnamon. The differences in response are possibly attributed to the varying quantity and quality of silicate minerals present in each spice sample. PSL signals of all irradiated samples reduced after 3 and 6 months storage. The results of this study provide a useful database on the applicability of PSL technique for the detection of Malaysian irradiated spices.

Identifying irradiated flours by photo-stimulated luminescence technique

Photo-stimulated luminescence (PSL) technique was used in this study to detect gamma irradiation treatment of five types of flours (corn, rice, tapioca, wheat and glutinous rice) at four different doses 0, 0.2, .05 and 1kGy. The signal level was compared with two threshold values (700 and 5000). With the exception of glutinous rice, all irradiated samples produced a strong signal above the upper threshold (5000 counts/60s). All control samples produced negative result with the signals below the lower threshold (700 counts/60s) suggesting that the samples have not been irradiated. Irradiated glutinous rice samples produced intermediate signals (700 - 5000 counts/60s) which were subsequently confirmed using calibrated PSL. The PSL signals remained stable after 90 days of storage. The findings of this study will be useful to facilitate control of food irradiation application in Malaysia.

Effect of load variation and shearing direction on the phase measurement in shearography

The application of laser shearography is becoming an acceptance tools in industrial NDT and material evaluation. The method has an advantage over other techniques due to non-contact real time measurement via a CCD camera. Recent application shows that this technique could offer a quantitative analysis in determining the magnitude of defect and strain of an inspected object. However problem of error in measurement particularly related to the optical phase change is a major concerned, it is known that the magnitude of the optical phase error could be associated with the optical, mechanical and electronics factors. This paper describes the effect of relative maximum phase change difference with load variation for difference shearing amount and the optical phase magnitude change with the change of shearing direction. Experiment used cantilever beam clearly indicated that the error difference with the variation of load applied to a maximum fringe density of 5mm shearing amount provides 6-12% compared with 10-12% of 15mm shearing amount. The phase magnitude changes its sign from negative to positive value in contrary to the direction of upper speckle shearing.The application of laser shearography is becoming an acceptance tools in industrial NDT and material evaluation. The method has an advantage over other techniques due to non-contact real time measurement via a CCD camera. Recent application shows that this technique could offer a quantitative analysis in determining the magnitude of defect and strain of an inspected object. However problem of error in measurement particularly related to the optical phase change is a major concerned, it is known that the magnitude of the optical phase error could be associated with the optical, mechanical and electronics factors. This paper describes the effect of relative maximum phase change difference with load variation for difference shearing amount and the optical phase magnitude change with the change of shearing direction. Experiment used cantilever beam clearly indicated that the error difference with the variation of load applied to a maximum fringe density of 5mm shearing amount provides 6-12% compared with 10-12% of 15mm shearing amount. The phase magnitude changes its sign from negative to positive value in contrary to the direction of upper speckle shearing.

Potential application of laser shearography for analysis of corrosion in petroleum pipeline

This paper aims at assessing of corrosion defects in standard petroleum pipelines by shearography method. Shearography reveals the stress-affected zone due to additional loading that can be realized by the laser speckle correlation on the inspected object. In this study, the artificial corrosion in pipeline is modeled by creating circular defects of different depths and sizes. An internal air pressure was exerted to the 7mm thick pipe wall. The results show that change of internal pressure is an effective means to reveal corrosion activity in the pipelines. The speckle correlation for corrosion of more than 3mm depth with ▵P≥0.24MPa can clearly be observed. For comparison, radiography technique is used to correlate the depth and size of the corrosion defects and finally to detect the location of the corrosion area.