Displaying publications 1 - 20 of 89 in total

  1. Sakinah Ariffin, Azhar Mohamad, Ratnam, Wickneswari
    Jurnal Sains Nuklear Malaysia, 2012;24(1):91-101.
    Colour is one of the most important traits in orchids and has created great interest in breeding programmes. Gamma irradiation is an alternative way for generation of somaclonal variation for new flower colours. Phenotypic changes are usually observed during screening and selection of mutants. Understanding of targeted gene expression level and evaluation of the changes facilitate in the development of functional markers for selection of desired flower colour mutants. Four Dendrobium orchid sequences (NCBI accessions: AM490639, AY41319, FM209429 and DQ462460) were selected to design gene specific primers based on information for chalcone synthase (CHS) from NCBI database. Quantitative real-time PCR (qPCR) was used to understand flower colour expression quantitatively derived from the CHS gene activities in different flower tissues (petal and sepal) from control Dendrobium Sonia (red purple), mutant DS 35-1/M (purple pink) and mutant DS 35-WhiteA. It was found that expression of CHS gene was highest in sepals of white flowers and lowest in both sepals and petals of purple pink flowers. Genomic DNA was amplified and PCR products were sequenced, aligned and compared. Sequence variations of CHS partial gene in Dendrobium Sonia mutants with different flower colour showed that two protein positions have been changed as compared to the control. These non-synonymous mutations may have contributed to the colour alterations in the white and purple pink mutants. This paper describes important procedures to quantify gene expression such as RNA isolation (quantity and quality), cDNA synthesis and primer design steps for CHS genes.
  2. Mei-Wo, Yii, Kamarozaman Ishak, Nooruzainah Abu Hassan, Maziah Mahmud, Khairul Nizam Razali
    Jurnal Sains Nuklear Malaysia, 2012;24(1):102-112.
    IAEA Soil-6 is a reference material with a certified value for 226Ra fall between 69.6 – 93.4 Bq/kg at 95% confidence level. This material has been used as a sample and performed repeat measurement weekly between years 2006 – 2009 using a same gamma spectrometry system. The activity concentration of this material is calculated automatically using the operational commercial software and compared with activity obtained from the manual calculation. Study found that only 76.9%, 64.1%, 56.3%, and 79.3% of the results from the software calculation lie within the confidence level for year 2006, 2007, 2008 and 2009, respectively. However, u-score calculation revealed that 94.9 %, 89.7%, 79.2% and 84.9% data set have no significant bias (u < 2.58) for year 2006, 2007, 2008 and 2009, respectively. On the other hand, all manual calculation data were found to be within the 95 % confidence level. Factors suspected to cause differences between these two approaches were discussed here. Manually peak search, marking and calculation still remains as the preferred option for calculating the gamma radionuclides activity unless limitations of the spectrum analysis software, as described in this paper can be resolved/improved upon.
  3. Nor Mariah Adam, Rosli Darmawan
    One of the most prevailing issues in the operation of Nuclear Reactor is the safety of the system. Worldwide publicity on a few nuclear accidents as well as the notorious Hiroshima and Nagasaki bombing have always brought about public fear on anything related to nuclear. Most findings on the nuclear reactor accidents are closely related to the reactor cooling system. Thus, the understanding of the behaviour of reactor cooling system is very important to ensure the development and improvement on safety can be continuously done. Throughout the development of nuclear reactor technology, investigation and analysis on reactor safety have gone through several phases. In the early days, analytical and experimental methods were employed. For the last three decades ID system level codes were widely used. The continuous development of nuclear reactor technology has brought about more complex system and processes of nuclear reactor operation. More detailed dimensional simulation codes are needed to assess these new reactors. This paper discusses the development of 3D CFD usage in nuclear reactor safety analysis worldwide. A brief review on the usage of CFD at Malaysia's Reactor TRIGA PUSPATI is also presented.
  4. Rasif Mohd Zain, Roslan Yahya, Mohamad Rabaie Shari, Airwan Affandi Mahmood, Mior Ahmad Khusaini Adnan
    Many times a year natural gas transmission and distribution companies need to make new connections to pipelines to expand or modify their existing system through hot tapping procedure. This procedure involves the installation of a new pipeline connection while the pipeline remains in service, flowing natural gas under pressure. The hot tap procedure includes attaching a branch connection and valve on the outside of an operating pipeline, and then cutting out the pipe-line wall within the branch and removing the wall section, which is called object of coupon through the valve. During the hot tapping process a critical problems occurred when a coupon fell into the mother pipeline. To overcome this problem, a gamma-ray absorption technique was chosen whereby a mapping technique will be done to detect the coupon position. The technique is non-destructive as it applies Co-60 (5mCi) as a radioisotope sealed source to emit gamma radiation and a NaI(Tl) scintillation as detector. The result provided a visible representation of density profile inside pipeline where the coupon location can be located. This paper provides the detail of the technique used and presents the result obtained.
  5. Yusof Abdullah, Mohd Reusmaazran Yusof, Nadira Kamarudin, Paulus, Wilfred Sylvester, Rusnah Mustaffa, Nurazila Mat Zali, et al.
    Al/B4C composites with 0 wt.%, 5 wt.% and 10 wt.% of B4C were prepared by powder metallurgy and their properties were characterised successfully. Investigation of the effect of milling times (4, 8, 12, 16 hours) on microstructure, phase identification, hardness and neutron attenuation coefficient of composites has been studied. The results showed that hardness increased with increased of milling time, with maximum hardness obtained at 16 hours milling time. The increment is slower as the composition of B4C increased. The hardness of Al/10%B4C, Al/5%B4C and Al/0%B4C were 81.7, 78.7 and 61.2 HRB respectively. Morphology of scanning electron microscopy (SEM) showed that microstructures play important role in controlling the hardness. Meanwhile, x-ray diffraction (XRD) analysis showed the phases and crystalline present in composites with an indication that crystalline of the grain increased as the milling time increased. Neutron absorption of Al/10%B4C composites showed that this composite has the highest attenuation coefficient, thus indicating that it is the best composites for neutron shielding.
  6. Mohd Reusmaazran Yusof, Yusof Abdullah
    Nuclear grade (high-purity) graphite for fuel element and moderator material in Advanced Gas
    Cooling Reactors (AGR) displays large scatter in strength and a non-linear stress-strain response from the damage accumulation. These responses can be characterized as quasi-brittle behaviour. Current assessments of fracture in core graphite components are based on the linear elastic approximation and thus represent a major assumption. The quasi-brittle behaviour gives challenge to assess the real nuclear graphite component. The selected test method would help to bridge the gap between microscale to macro-scale in real reactor component. The small scale tests presented here can contribute some statistical data to manifests the failure in real component. The evaluation and choice of different solution design of biaxial test will be discussed in this paper. The ball on-three ball test method was used for assessment test follows by numerous of analytical method. The results shown that biaxial strength of the EY9 grade graphite depends on the method used for evaluation. Some of the analytical methods use to calculate biaxial strength were found not to be valid and therefore should not be used to assess the mechanical properties of nuclear graphite.
  7. Radaideh, K.M., Matalqah, L.M., Tajuddin, A.A., Lee Luen, F.W., Bauk, S., Abdel Munem, E.M.E
    The ultimate check of the actual dose delivered to a patient in radiotherapy can be achieved by using dosimetric measurements. The aims of this study were to develop and evaluate a custom handmade head and neck phantom for evaluation of Three-Dimensional Conformal Radiation Therapy (3D-CRT) dose planning and delivery. A phantom of head and neck region of a medium built male patient with nasopharyngeal cancer was constructed from Perspex material. Primary and secondary Planning Target Volume (PTV) and twelve Organs at Risk (OAR) were delineated using Treatment Planning System (TPS) guided by computed tomography printout transverse images. One hundred and seven (107) holes distributed among the organs were loaded with Rod-shaped Thermoluminescent dosimeters (LiF:Mg,Ti TLDs) after common and individual calibration. Head and neck phantom was imaged, planned and irradiated conformally (3D-CRT) by linear accelerator (LINAC Siemens Artiste). The planned predicted doses by TPS at PTV and OAR regions were obtained and compared with the TLD measured doses using the phantom. Repeated TLD measurements were reproducible with a percent standard deviation of < 3.5%. Moreover, the average of dose discrepancies between TLDs reading and TPS predicted doses were found to be < 5.3%. The phantom’s preliminary results have proved to be a valuable tool for 3D-CRT treatment dose verification.
  8. Khairiah Yazid @ Khalid, Roslan Yahya, Nadira Kamarudini, Mohd. Zaid Abdullah, Mohd Ashhar Khalid, Abdul Aziz Mohamed
    Detection and analysis of resin is particularly significant since the commercial value of agarwood is related to the quantity of resins that are present. This article explores the potential of a scanning electron microscope in combination with new non-destructive 3D visualization technique, X-ray micro-computed tomography, as imaging tools to visualize micro-structure resin in agarwood. These techniques were used to compare two samples of agarwood chips: high grade and low grade. From the results, it can be concluded that a wood cell filled with resin deposit have a higher attenuation. It can be shown that the combination of scanning electron microscopy and micro-CT can offer high resolution images concerning the localization and structure of resin inside Agarwood. While the second allows the 3D investigation of internal structure of agarwood, the first technique can provide details 2D morphological information. These imaging techniques, although sophisticated can be used for standard development especially in grading of agarwoodlbr commercial activities.
  9. Noraishah Othmanl, Nor Pa' iza M. Hasani, Juhari Mohd Yusof, Roslan Yahya, Mohd Amirul Syafiq
    Flow measurement is a critical element for liquid resources monitoring for various applications in many industrial systems. The purposes of the study are to determine the flow rate of liquid system in flow rig using radiotracer techniques and to compare the result with that obtained by the conventional flow meters. The flow rig consists of 58.7m long and 20cm diameter pipeline that can accommodate about 0.296m3 of liquid. Tap water was used as liquid flow in pipeline and conventional flow meters were also installed at the flow rig. Radiotracer was injected as a sharp pulse into the inlet p.peline. The pulse was monitored at the inlet and various points along the outlet pipeline using collimated scintillation detector. The peak to peak and total count methods were applied for radiotracer techniques and showed the comparable results with conventional flow meter.
  10. Md Suhaimi Elias, Mohd Suhaimi Hamzah, Mohd Suhaimi Hamzah, Siong, Wee Boon, Nazaratul Ashifa Abdullah Salim
    Assessment of source and sediment quality was carried out on marine sediments collected from the Tuanku Abdul Rahman National Park. Enrichment factors (EF), pollution load index (PLI) and geo-accumulation index (Igeo) were used to identify the sources of pollution, degree of contamination and sediment quality, respectively. Elemental analyses of marine sediment samples were performed by using the Instrumental Neutron Activation Analysis (INAA). Results from the Tunku Abdul Rahman National Park of Sabah indicated that most of the elements are considered to be from lithological or natural origin with EF values of less than 2 except for As (10 stations), Cr (3 stations), Lu (5 stations), Mg (2 stations), Sb (6 stations) and U (3 stations). For the sediment quality, most of the study area can be categorised as unpolluted for most of the elements (Igeo value < 2) except for As, Cr, Lu, Mg, Sb and U. A few study areas were slightly low contaminated with As, Cr, Lu, Mg, Sb and U. The contamination of As, Cr, Lu, Mg, Sb and U in the study area can be categorised as moderate with Igeo values ranged from 1 to 2. Meanwhile, the results of PLI value for sediment were ranged from 0.93 to 1.47 (PLI < 50) indicating there are not required to perform drastic rectification measures for the screening of the elements in the Tunku Abdul Rahman Park. Overall, assessment of the sediment quality at the Tunku Abdul Rahman National Park showed a few elements such as As, Cr, Lu, Mg, Sb and U were slightly enriched while most of the elements were similar to background values.
  11. Fatema Anuar, Mohammed Iqbal Shueb, Ruzitah Mohd Salleh, Nazaratul Ashifa Abdullah Salim, Julia Abdul Karim
    Mechanical properties of blended polyethylene (PE) containing the antioxidant Irganox 1010 and the UV-absorber Tinuvin 326 were studied for future use as radiation capsule material for the TRIGA Mark II research reactor. High density and low density polyethylene were blended with the additives and tested for elongation at break, impact strength and gel content, before and after irradiation inside the nuclear reactor. Characterization via FTIR as well as determination of crystallization and melt transition temperatures through DSC were also conducted. It was found that the addition of the antioxidant at different amounts (from 0 to 4 phr) had various effects on the properties of the blended PE, with 0 phr being the amount at which there was the biggest increase in elongation at break and impact strength, post-irradiation.
  12. Md Fakarudin Ab Rahman, Ismail Mustapha, Nor Pa’iza Mohd Hasan, Ibrahim, Pairu
    In industrial plants such as electricity generating, petroleum, chemical and petrochemical plants, pipelines are used extensively to transport liquid from one location to another. In radiation vulcanization of natural rubber latex (RVNRL) plants, pipelines are also used to transport latex to storage tank. During one of its maintenance activities, a pipeline intelligent gauge (PIG) that was used to monitor pipe integrity jammed inside the pipe causing interruption to its operation or loading activities. Sealed source technology was utilized to determine the location of jammed PIG in the pipeline. Fast neutrons from a 50 mCi Americium Beryllium (AmBe241), with energy range between 0.5 to11 MeV, were used for the study. Helium 3 (He3) detector was used to detect slow neutrons having a range of energy of 30 eV- 0.5 MeV. The investigation was carried out using neutron backscatter technique scanner. By adopting back-scattered technique, the location of jammed PIG in the pipeline has been successfully determined.
  13. Muhamat Omar, Zalina Laili, Julia Abdul Karim, Zarina Masood, Nik Marzukee Nik Ibrahim, Mohd Abd Wahab Yusof
    A study to assess the concentration of radionuclides in spent resins of the PUSPATI TRIGA Mark II reactor coolant purification system has been carried out. Fresh spent resins collected and analysed in May 2010, after the changing of leaked heat exchanger in Sept. 2009 was found to contain 24Na, 122Sb, 51Cr, 124Sb, 58Co, 65Zn, 54Mn and 60Co. Old spent resins removed in 2001 and 2002 but analysed in 2010 indicated the presence of 60Co and 152Eu as radionuclides with half-lives of < 1 year might have already been decayed out. These results can be used to establish radionuclide inventory of the spent resins as part of radiation protection programme.
  14. Ros Anita Ahmad Ramli, Ahmad Zainuri Mohd Dzomir, Zainon Othman, Wan Saffiey Wan Abdullah, Muhamad Samudi Yasir
    The exposure of food to ionizing radiation is being progressively used in many countries to
    inactivate food pathogens, to eradicate pests and to extend shelf-life of food. To ensure free
    consumer choice, irradiated food will be labeled. The availability of a reliable method to detect
    irradiated food is important to enforce legal controls on labeling requirements, ensure proper
    distribution and increase consumer confidence. This paper reports on the preliminary application
    of photostimulated luminescence technique (PSL) as a potential method to detect irradiated food
    and perhaps be used for monitoring irradiated food on sale locally in the near future. Thus this
    study will be beneficial and relevant for application of food irradiation towards improving food
    safety and security in Malaysia.
  15. Nurrul Assyikeen Md. Jaffary, Wo, Yii Mei, Abdul Kadir Ishak, Noor Fadzilah Yusof, Kamarozaman Ishak, Maziah Mahmud, et al.
    On March 11, 2011, a serious accident occurred in Daiichi nuclear reactor plant, Fukushima,
    Japan which caused radioactive materials been released into the atmosphere in the form of
    aerosols and dust particles. Sea water around the plant was also found contaminated with high
    radioactivity readings. These radioactive materials could be transported by the winds and ocean
    current across international borders and cannot be controlled by human. Thus, a continuous
    monitoring activity of radionuclide content in the air and sea water needs to be conducted by the
    authorities. In addition to radioactivity monitoring, Malaysia should also control the entry of
    contaminated food in order to prevent radionuclide ingestion by human. The radionuclide 131I,
    134Cs and 137Cs were used as a measure of pollution levels and counted with gamma spectrometry
    using standard analysis method suggested by AOAC International. In this paper, details description
    of the role of Radiochemical and Environment Group, Nuclear Malaysia who’s responsible in
    analyzing the radioactivity in the food samples due to Fukushima Daiichi, Japan accident was
    included. The radioactivity limit adopted and analysis results from this monitoring were discussed
  16. Nur Humaira’ Lau Abdullah, Zal U’yun Wan Mahmood, Norfaizal Mohamed @ Muhamad, Nazaratul Ashifa Abdullah Salim, Ahmad Nazrul Abd Wahid, Nor Dalila Desa, et al.
    A glasshouse experiment was performed to evaluate the uptake of grasses viz. Napier and Vetiver
    in radiophytoremediation of caesium-contaminated soil. The radiophytoremediation experiment
    was designed according to the Randomized Complete Block Design (RCBD). The grasses were
    grown in troughs filled with soil mixed with a known specific activity of 134Cs. Initial Cs activity and
    activity after different cultivation time intervals of 1, 3, 6 and 9 months were analyzed using gamma
    spectrometer direct measurement. The results showed the uptake of caesium by Napier and Vetiver
    after 9 months with the transfer factors (TF) were 4.70 and 6.25, respectively. The remediation of
    caesium from the contaminated soil during the study period was 98.08% for Napier and 98.21% for
    Vetiver. Both grasses have been found to accumulate caesium, with Vetiver accumulating higher
    than Napier. Thus, the present study suggests that Vetiver could be used as a potential plant for
    radiophytoremediation of caesium.
  17. Norhayati Abdullah, Wong, Jeannie Hsiu Ding, Ng, Kwan Hoong, Ung, Ngie Min
    The assessment of surface dose is essential in radiotherapy to avoid deterministic effect or to
    reduce the severity of side effects from radiation treatment. In this study, the surface dose for breast
    cancer radiotherapy was measured using two types of dosimeter; Thermoluminescent Dosimeter
    (TLD) and Optically Stimulated Luminescent Dosimeter (OSLD). The study was performed on the
    left breast of female Alderson Radiation Therapy (ART) phantom. The treatment planning was
    carried out on the ART phantom to determine the homogeneity of dose distribution within the target
    organ is complied with the tolerance limits of 95% to 107% as recommended by the International
    Commission on Radiation Units and Measurements (ICRU)’s Report No. 50. From the treatment
    planning result, the phantom then was irradiated with 267 cGy dose per fraction for two beam
    fields; medial tangential and lateral tangential fields using a 6 MV photon beam produced from
    three-dimensional (3D) conformal radiotherapy. Result shows that the OSLD provides 25.7% and
    23.5% higher surface dose compared to TLD for medial tangential and lateral tangential fields,
    respectively. This condition may be due to higher effective point of measurement and angular
    dependence of the OSLD compared to TLD. As a conclusion, suitable dosimeter should be selected
    to ensure accurate estimation of surface dose could be made thus reduction of skin reaction to
    patient could be achieved.
  18. Selambakkan, Sarala, Khomsaton Abu Bakar, Jamaliah Shariff, Suhairi Alimon
    This paper studies about water obtained from fish pond of fisheries research centre. Usual water
    quality parameters such as pH, COD, Turbidity and Ammonia content were analyzed before and
    after irradiation. Electron beam irradiation was used to irradiate the water with the dose 100 kGy,
    200 kGy and 300 kGy. Only high dose was applied on this water as only a limited amount of
    samples was supplied. All the parameters indicated a slight increase after irradiation except for the
    ammonia content, which showed a gradual decrease as irradiation dose increases. Sample
    condition was changed before irradiation in order to obtain more effective results in the following
    batch. The water sample from fisheries was diluted with distilled water to the ratio of 1:1.This was
    followed with irradiation at 100 kGy, 200 kGy and 300 kGy. The results still showed an increase in
    all parameters after irradiation except for ammonia content. For the following irradiation batch,
    the pH of the sample was adjusted to pH 4 and pH 8 before irradiation. For this sample the
    irradiation dose selected was only 100 kGy. A higher value of ammonia was observed for the
    sample with pH 4 after irradiation. Other parameters were almost the same as the first two batches
  19. Muhammad Rawi Mohamed Zin, Mahendrasingam, Arumugam, Konkel, Chris, Narayanan, Theyencheri
    Changes in molecular structure configuration during strain induced crystallisation of an amorphous Poly(Lactic Acid) (PLA 4032D) polymer was monitored in-situ by simultaneously recording the wide angle x-ray scattering (WAXS) and small angle x-ray scattering (SAXS) patterns together with polymer deformation images and force data. The amorphous chain orientation from the beginning of deformation until the onset of crystallisation was studied from the WAXS patterns. The true mechanical behaviour described by the true stress-true strain curve related to an amorphous chain orientation exhibited a linear behaviour. Approaching critical amorphous orientation, the true stress-true strain curve deviated from linear into non-linear behaviour. After the onset of crystallization, when the deformed polymer became a semicrystalline state, the true mechanical behaviour exhibited true strain hardening which greatly affected by the formation of the morphology. The gradual true strain hardening was associated with the formation of micro-fibrillar structure containing thin crystallite morphology whilst sharp increased in true strain hardening was associated with the formation of stacked lamellar morphology in the form of macro-lattice structure. The study was accomplished by the application of high brilliance synchrotron radiation at beamline ID2 of ESRF, Grenoble in France and the usage of the high contrast resolution of WAXS and SAXS charge-couple device (CCD) camera as well as 40 milliseconds temporal resolution of data acquisition system.
  20. Norpaiza Mohamad Hasan, Noraini Haron, Mohamad, Glam Hadzir Patai, Ismail Mustapha, Syed Yusainee Syed Yahya
    Paper recycling plants usually buy their raw material from suppliers. More than often, bulk used paper supplied to the plant contains some significant quantity of water in its internal voids. It may be included intentionally or unintentionally. The price of used paper depends on its weight, thus adding water will help to increase weight and consequently increase the price. In this way, plant owner who purchase the used paper suffers a significant of financial lost. The objectives of our experiment are to establish a calibration curve that correlate between the amount of neutron backscattered and water content, and finally to develop a correction factor that need to be introduced to the measured values of water content. A fast neutron source (Am-Be 241) and a portable backscattering neutron detector were used for water measurement. The experiments were carried out by measuring neutron backscattering from used paper that has been added with different amount of water. As a result, a neutron calibration curve that provides a correlation between neutron backscattering and water content was established.
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