Displaying publications 21 - 40 of 156 in total

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  1. Effect of gamma irradiation on poly(vinyledene difluoride)-lithium bis(oxalato)borate electrolyte
    Abdul Rahaman MH, Khandaker MU, Khan ZR, Kufian MZ, Noor IS, Arof AK
    Phys Chem Chem Phys, 2014 Jun 21;16(23):11527-37.
    PMID: 24801055 DOI: 10.1039/c4cp01233j
    A poly(vinyledene difluoride)-lithium bis(oxalato)borate solid polymer electrolyte prepared by a solvent casting method has been irradiated with different doses of gamma-rays. Differential scanning calorimetry reveals that the polymer electrolyte irradiated with 35 kGy of γ-rays is the most amorphous sample. This is also supported by the results obtained from X-ray diffraction. The Fourier transform infrared spectrum of each irradiated sample has been deconvoluted in the wavenumber region between 1830 and 1758 cm(-1) in order to predict the percentage of free and contact ions in the samples. The sample exposed to 35 kGy of γ-rays contains the highest percentage of free ions and the lowest amount of contact ions. This sample also exhibits the highest room temperature conductivity of 3.05 × 10(-4) S cm(-1), which is 15% higher relative to the virgin sample. The number density of free ions is observed to have more control on the conductivity variation with the γ-radiation dose compared to ionic mobility. This study confirms that γ-irradiation can be a potential way to obtain highly conductive and mechanically stable polymer electrolytes.
  2. Radionuclide emissions from a coal-fired power plant
    Amin YM, Khandaker MU, Shyen AK, Mahat RH, Nor RM, Bradley DA
    Appl Radiat Isot, 2013 Oct;80:109-16.
    PMID: 23891979 DOI: 10.1016/j.apradiso.2013.06.014
    Current study concerns measurement of radioactivity levels in areas surrounding a 2420 MW thermal power plant fueled predominantly by bituminous coal. The concentrations of (226)Ra, (232)Th and (40)K in onsite bottom-ash were found to be 139 Bq/kg, 108 Bq/kg and 291 Bq/kg, respectively, the levels for these radiolnuclides in soil decreasing with distance from the power plant. At the plant perimeter the respective radionuclide concentrations were 87 Bq/kg, 74 Bq/kg and 297 Bq/kg. In a nearby town, the corresponding concentrations were 104 Bq/kg, 52 Bq/kg and 358 Bq/kg, suggestive of use of TENORM affected soils. The mean radium equivalent activities (Raeq) in soil and ash sample in the town were 205 Bq/kg and 316 Bq/kg, respectively. The Kapar plant ash/slag appears to contain a higher level of TENORM than the world average. The degree of contamination is much higher inside the town where slag has been mixed with topsoil as landfill or as simple domestic waste. For the prevailing levels of exposure and a worst case senario, the predicted committed effective dose due to ingestion and inhalation for intake durations of 1- and 30 years would be 4.2 μSv and 220 μSv, respectively.
  3. The presence of natural radioactivity and 137Cs in the South China Sea bordering peninsular Malaysia
    Amin YM, Mahat RH, Nor RM, Khandaker MU, Takleef GH, Bradley DA
    Radiat Prot Dosimetry, 2013 Oct;156(4):475-80.
    PMID: 23584496 DOI: 10.1093/rpd/nct097
    The presence of natural radioactivity and (137)Cs has been investigated in fresh media obtained from South China Sea locations off the coast of peninsular Malaysia. The media include seafood, sea water and sediment. The samples were collected some weeks prior to the devastating 2011 Tōhoku earthquake and associated tsunami, the occurrence of which precipitated the Fukushima incident. All samples showed the presence of naturally occurring (226)Ra, (228)Ra and primordial (40)K, all at typically prevailing levels. The concentrations of natural radioactivity in molluscs were found to be greater than that of other marine life studied herein, the total activity ranging from 337 to 393 Bq kg(-1) dry weight. The total activity in sea water ranged from 15 to 88 Bq l(-1). Sediment samples obtained at deep sea locations more than 20 km offshore further revealed the presence of (137)Cs. The activity of (137)Cs varied from ND to 0.5 Bq kg(-1) dry weight, the activity increasing with offshore distance and depth. The activity concentrations presented herein should be considered useful in assessing the impact of any future radiological contamination to the marine environment.
  4. Production cross-sections of radionuclides from α-induced reactions on natural copper up to 50MeV
    Usman AR, Khandaker MU, Haba H, Otuka N, Murakami M, Komori Y
    Appl Radiat Isot, 2016 08;114:104-13.
    PMID: 27227905 DOI: 10.1016/j.apradiso.2016.04.027
    The excitation functions were measured for the (nat)Cu(α,x)(66,67)Ga,(65)Zn,(57,58,60)Co reactions in the energy range of 16.5 -50MeV. A conventional stacked-foil activation technique combined with HPGe γ-ray spectrometry was employed to determine cross-sections. The measured cross-sections were critically compared with relevant previous experimental data and also with the evaluated data in the TENDL-2014 library. Present results confirmed some of the previous experimental data, whereas only a partial agreement was found with the evaluated data. The measured data are useful for reducing the existing discrepancies in the literature, to improve the nuclear reaction model codes, and to enrich the experimental database towards various applications.
  5. Measurement of radioactivity and heavy metal levels in edible vegetables and their impact on Kuala Selangor communities of Peninsular Malaysia
    Asaduzzaman Kh, Khandaker MU, Amin YM, Zainuddin Z, Farook MS, Bradley DA
    Radiat Prot Dosimetry, 2015 Nov;167(1-3):165-70.
    PMID: 25935008 DOI: 10.1093/rpd/ncv237
    Vegetable is an essential daily diet item for the people of Malaysia. This work addressed the radiation and heavy metal exposure scenarios through the consumption of vegetables. Kuala Selangor is located in Sungai Selangor estuary in the west coast of Peninsular Malaysia, which is susceptible to pollution load due to the presence of large-scale industrial and human activities. Radioactivity and heavy metals level in human diet is of particular concern for the assessment of possible radiological and chemical hazards to human health. Therefore, a comprehensive study was carried out to determine the radioactivity levels ((226)Ra, (228)Ra and (40)K) and heavy metal concentrations (Cr, As, Cd, Mn, Mg, Al, Sr, Rb, Sb, Ba, Hg, Fe, Ni, Zn, Cu, Bi and Pb) in 10 varieties of vegetable collected from different farmlands in Kuala Selangor region. The committed doses for (226)Ra, (228)Ra and (40)K due to consumption of vegetables were found 16.6±1.3, 23.6±1.7 and 58±5 µSv y(-1), respectively, with a total of 98±8 µSv y(-1). This dose imposes no significant threat to human health. The estimated cancer risk shows that probability of increase in cancer risk from daily intake of vegetables is only a minor fraction of International Commission on Radiological Protection values. The concentrations of heavy metal were below the daily intake recommended by the international organisations.
  6. Cyclotron production of no carrier added 186gRe radionuclide for theranostic applications
    Khandaker MU, Nagatsu K, Minegishi K, Zhang MR, Jalilian AR, Bradley DA
    Appl Radiat Isot, 2020 Sep 15;166:109428.
    PMID: 32979754 DOI: 10.1016/j.apradiso.2020.109428
    186gRe (T1/2 = 3.7183 d, E(β-)mean = 346.7 keV, I(β-)mean = 92.59%), a mixed beta and γ-emitter shows great potential for use in theranostic applications. The dominant 185Re(n,γ) route, via use of a nuclear reactor, provides 186gRe in carrier added form with low specific activity, while cyclotrons offer no carrier-added (NCA) high specific activity production of 186gRe. However, to be able to select the best possible nuclear reaction and to optimize the production route via the use of a cyclotron, information on the excitation function for the reaction of interest as well as for the competing reactions is necessary. Accordingly, we have conducted a detailed study of the excitation functions for natW(d, x) reactions in seeking optimized parameters for the NCA production of 186gRe. Noting a discrepancy among the experimental data, we made an evaluation of the available literature, finally selecting optimum parameters for the production of 186gRe via the 186W(d,2n)186Re reaction. These beam parameters were then used for batch production of 186gRe by irradiating an enriched 186W metallic powder target, followed by a subsequent automated chemical separation process. The preliminary results show 98.1% radionuclidic purity of 186gRe at 8 h subsequent to the End of Bombardment (EOB), offering the potential for use in clinical applications.
  7. Fulltext Development of a Robust Multi-Scale Featured Local Binary Pattern for Improved Facial Expression Recognition
    Yasmin S, Pathan RK, Biswas M, Khandaker MU, Faruque MRI
    Sensors (Basel), 2020 Sep 21;20(18).
    PMID: 32967087 DOI: 10.3390/s20185391
    Compelling facial expression recognition (FER) processes have been utilized in very successful fields like computer vision, robotics, artificial intelligence, and dynamic texture recognition. However, the FER's critical problem with traditional local binary pattern (LBP) is the loss of neighboring pixels related to different scales that can affect the texture of facial images. To overcome such limitations, this study describes a new extended LBP method to extract feature vectors from images, detecting each image from facial expressions. The proposed method is based on the bitwise AND operation of two rotational kernels applied on LBP(8,1) and LBP(8,2) and utilizes two accessible datasets. Firstly, the facial parts are detected and the essential components of a face are observed, such as eyes, nose, and lips. The portion of the face is then cropped to reduce the dimensions and an unsharp masking kernel is applied to sharpen the image. The filtered images then go through the feature extraction method and wait for the classification process. Four machine learning classifiers were used to verify the proposed method. This study shows that the proposed multi-scale featured local binary pattern (MSFLBP), together with Support Vector Machine (SVM), outperformed the recent LBP-based state-of-the-art approaches resulting in an accuracy of 99.12% for the Extended Cohn-Kanade (CK+) dataset and 89.08% for the Karolinska Directed Emotional Faces (KDEF) dataset.
  8. Commercial kitchenware glass as a potential thermoluminescent media for retrospective dosimetry
    Wahib NB, Khandaker MU, Aqilah Binti Mohamad Ramli N, Sani SFA, Bradley DA
    Appl Radiat Isot, 2019 Jun;148:218-224.
    PMID: 31003071 DOI: 10.1016/j.apradiso.2019.04.001
    Study has been made of the thermoluminescence (TL) yield of various glass-based commercial kitchenware (Reko-China, Skoja-France, Godis-China, Glass Tum-Malaysia, Lodrat-France). Interest focuses on their potential for retrospective dosimetry. Use was made of a60Co gamma-ray irradiator, delivering doses in the range 2-10 Gy. Results for the various media show all the glassware brands to yield linearity of response against dose, with a lower limit of detection of ∼0.06 and ∼0.08 Gy for loose and compact powdered samples. Among all of the brands under study, the Lodrat glassware provides the greatest sensitivity, at 6.0 E+02 nC g-1 Gy-1 and 1.5E+03 nC g-1 Gy-1 for compact- and loose-powdered forms respectively. This is sufficiently sensitive to allow its use as a TL material for accident dosimetry (2 Gy being the threshold dose for the onset of a number of deterministic biological effects, including skin erythema and sterility). Energy Dispersive X-ray (EDX) analyses have been conducted, showing the presence of a number of impurities (including C, O, Na, Mg, Al, Si, Ca and Br). Fading of the irradiated glasses show the amount of better than 3% and 5% of the stored energy for both loose and compact powdered samples within 9 days post irradiation. As such, commercial kitchenware glass has the potential to act as relatively good TL material for gamma radiation dosimetry at accident levels. This is the first endeavour reporting the TL properties of low cost commercial kitchenware glasses for gamma-ray doses in the few Gy range, literature existing for doses from 8 Gy to 200 Gy.
  9. Evaluation of Ge-doped silica fibre TLDs for in vivo dosimetry during intraoperative radiotherapy
    Moradi F, Ung NM, Mahdiraji GA, Khandaker MU, See MH, Taib NA, et al.
    Phys Med Biol, 2019 04 12;64(8):08NT04.
    PMID: 30840946 DOI: 10.1088/1361-6560/ab0d4e
    Ge-doped silica fibre (GDSF) thermoluminescence dosimeters (TLD) are non-hygroscopic spatially high-resolution radiation sensors with demonstrated potential for radiotherapy dosimetry applications. The INTRABEAM® system with spherical applicators, one of a number of recent electronic brachytherapy sources designed for intraoperative radiotherapy (IORT), presents a representative challenging dosimetry situation, with a low keV photon beam and a desired rapid dose-rate fall-off close-up to the applicator surface. In this study, using the INTRABEAM® system, investigations were made into the potential application of GDSF TLDs for in vivo IORT dosimetry. The GDSFs were calibrated over the respective dose- and depth-range 1 to 20 Gy and 3 to 45 mm from the x-ray probe. The effect of different sizes of spherical applicator on TL response of the fibres was also investigated. The results show the GDSF TLDs to be applicable for IORT dose assessment, with the important incorporated correction for beam quality effects using different spherical applicator sizes. The total uncertainty in use of this type of GDSF for dosimetry has been found to range between 9.5% to 12.4%. Subsequent in vivo measurement of skin dose for three breast patients undergoing IORT were performed, the measured doses being below the tolerance level for acute radiation toxicity.
  10. TERRESTRIAL RADIONUCLIDES IN SURFACE (DAM) WATER AND CONCOMITANT DOSE IN METROPOLITAN KUALA LUMPUR
    Khandaker MU, Uwatse OB, Bin Shamsul Khairi KA, Faruque MRI, Bradley DA
    Radiat Prot Dosimetry, 2019 Dec 31;185(3):343-350.
    PMID: 30806465 DOI: 10.1093/rpd/ncz018
    Batu Dam is of considerable importance to the metropolis of Kuala Lumpur, its existence and the quality assessment of its waters being essential in helping to maintain the lives of a large sector of the Malaysian population. Concerning the level of naturally occurring radioactivity contained within its waters, a well characterised HPGe γ-ray technique has been used in making measurements of the concentrations of primordial radionuclides in samples of surface water from the Dam. Based on the mean individual daily consumption of dam water, estimation has been made of the concomitant radiation dose. Activity concentrations, in units of Bq l-1, have been found to be in the range 2.4-3.2 for 226Ra, 1.1-1.3 for 232Th and 22.7-40.7 for 40K, in line with literature data for surface waters. The total annual ingestion dose for infants (<1 y) and adolescents (12-17 y) are found to be significant and greater than the World Health Organization recommended maximum dose of 0.1 mSv y-1 from the imbibing of drinking water. However, the Dam water does not pose a threat to public health, the Dam water not being used as the sole source of drinking water. Noting that this is the only known study of water from Batu Dam, the reported levels allow for evaluation of future changes in the natural radioactivity profile.
  11. Evaluation of production cross-sections for theranostic 67Cu radionuclide via proton-induced nuclear reaction on 68Zn target
    Ali SKI, Khandaker MU, Al-Mugren KS, Latif SA, Bradley DA, Okhunov AA, et al.
    Appl Radiat Isot, 2021 Jul;173:109735.
    PMID: 33915407 DOI: 10.1016/j.apradiso.2021.109735
    Copper-67 (T1/2 = 61.83 h, Eβ-mean=141 keV, Iβ-total=100%; Eγ = 184.577 keV, Iγ = 48.7%) is a promising radionuclide for theranostic applications especially in radio immunotherapy. However, one of the main drawbacks for its application is related to its limited availability. Various nuclear reaction routes investigated in the last years can result in 67Cu production, although the use of proton beams is the method of choice taken into account in this work. The goal of this work is a revision of the cross-sections aimed at 67Cu yield, which were evaluated for the 68Zn(p,2p)67Cu reaction route up to 80 MeV proton energy. A well-defined statistical procedure, i.e., the Simultaneous Evaluation on KALMAN (SOK), combined with the least-squares concept, was used to obtain the evaluated data together with the covariance matrix. The obtained evaluated data were also compared to predictions provided by the nuclear reaction model codes TALYS and EMPIRE, and a partial agreement among them has been found. These data may be useful for both existing and potential applications in nuclear medicine, to achieve an improvement and validation of the various nuclear reaction models, and may also find applications in other fields (e.g., activation analysis and thin layer activation).
  12. Fulltext Development of a Novel Design and Subsequent Fabrication of an Automated Touchless Hand Sanitizer Dispenser to Reduce the Spread of Contagious Diseases
    Das A, Barua A, Mohimin MA, Abedin J, Khandaker MU, Al-Mugren KS
    Healthcare (Basel), 2021 Apr 10;9(4).
    PMID: 33920290 DOI: 10.3390/healthcare9040445
    BACKGROUND: The use of a touchless automated hand sanitizer dispenser may play a key role to reduce contagious diseases. The key problem of the conventional ultrasonic and infra-red-based dispensers is their malfunctioning due to the interference of sunlight, vehicle sound, etc. when deployed in busy public places. To overcome such limitations, this study introduced a laser-based sensing device to dispense sanitizer in an automated touchless process.

    METHOD: The dispensing system is based on an Arduino circuit breadboard where an ATmega328p microcontroller was pre-installed. To sense the proximity, a light-dependent resistor (LDR) is used where the laser light is to be blocked after the placement of human hands, hence produced a sharp decrease in the LDR sensor value. Once the LDR sensor value exceeds the lower threshold, the pump is actuated by the microcontroller, and the sanitizer dispenses through the nozzle.

    RESULTS AND DISCUSSION: A novel design and subsequent fabrication of a low-cost, touchless, automated sanitizer dispenser to be used in public places, was demonstrated. The overall performance of the manufactured device was analyzed based on the cost and power consumption, and environmental factors by deploying it in busy public places as well as in indoor environment in major cities in Bangladesh, and found to be more efficient and cost-effective compared to other dispensers available in the market. A comprehensive discussion on this unique design compared to the conventional ultrasonic and infra-red based dispensers, is presented to show its suitability over the commercial ones. The guidelines of the World Health Organization are followed for the preparation of sanitizer liquid. A clear demonstration of the circuitry connections is presented herein, which facilitates the interested individual to manufacture a cost-effective dispenser device in a relatively short time and use it accordingly. Conclusion: This study reveals that the LDR-based automated hand sanitizer dispenser system is a novel concept, and it is cost-effective compared to the conventional ones. The presented device is expected to play a key role in contactless hand disinfection in public places, and reduce the spread of infectious diseases in society.

  13. The potential of decorative building materials (marble) for retrospective thermoluminescence dosimetry
    Yasmin S, Khandaker MU, Nawi SNM, Sani SFA, Bradley DA, Islam MA
    Appl Radiat Isot, 2021 Sep;175:109782.
    PMID: 34082304 DOI: 10.1016/j.apradiso.2021.109782
    Among the various types of decorative materials used in Bangladeshi dwellings, the marble/marble stone is one of the most common ones that used largely for enhancing the beauty and/or aristocracy of the dwelling environment. In this study, the most commonly used, six types of marble stones, have been analyzed for retrospective accident dosimetry. With the interest of characterizing several key thermoluminescence properties to examine their potentiality for dosimetry, annealing - irradiation - readout steps have been done chronologically which comprises the analysis of glow curves, relative sensitivity, dose dependence, repeatability and fading. Considering the various TL parameters, marble 'Carrara' imported from Italy present relatively better capability for reconstruction of radiation dose in the dose range of 10-50 Gy. From fading result, it is clear that for reconstruction of absorbed dose up to four weeks of post exposure, the marble 'Carrara' is found to be the most reliable media among the studied marble types. The Zeff values for the various marble samples are found to be in the range of 13.65-19.12, comparing favorably in replace of TLD-200 (Zeff = 16.3) which can be used for low-level environmental radiation dosimetry. Present work constitutes the first study to investigate the potentials of marble stone for reconstruction of absorbed dose in the range of 10-50 Gy dose.
  14. Studies of thermoluminescence kinetic parameters of polymer pencil lead graphite under photon exposures
    Khandaker MU, Mat Nawi SN, Bradley DA, Lam SE, Abdul Sani SF, Sulieman A
    Appl Radiat Isot, 2021 Aug;174:109757.
    PMID: 33990033 DOI: 10.1016/j.apradiso.2021.109757
    This study analysed thermoluminescence (TL) glow curves of the polymer pencil lead graphite (PPLG) due to its potential applications in radiation dosimetry. The TL glow curves provide information on the physical parameters of the defects participating in luminescence process. The glow curves for different diameters PPLG samples were obtained with varying temperature from 50 to 300 °C, at a fixed heating rate of 10 °Cs-1. A number of methods (initial rise, peak shape and curve fitting) were used to fit the TL glow peaks of the PPLG samples obtained under photon dose of 200 Gy. From the fitted TL signals, the trap parameters such as the order of kinetics, the activation energy, the frequency factor, etc. for the individual peaks were numerically determined. The lifetimes of TL process were calculated assuming the first-order kinetics. The results are compared among the different methods adopted in this study. Implications about the possible results in glow curve deconvolution are discussed.
  15. Monte Carlo skin dose simulation in intraoperative radiotherapy of breast cancer using spherical applicators
    Moradi F, Ung NM, Khandaker MU, Mahdiraji GA, Saad M, Abdul Malik R, et al.
    Phys Med Biol, 2017 Jul 28;62(16):6550-6566.
    PMID: 28708603 DOI: 10.1088/1361-6560/aa7fe6
    The relatively new treatment modality electronic intraoperative radiotherapy (IORT) is gaining popularity, irradiation being obtained within a surgically produced cavity being delivered via a low-energy x-ray source and spherical applicators, primarily for early stage breast cancer. Due to the spatially dramatic dose-rate fall off with radial distance from the source and effects related to changes in the beam quality of the low keV photon spectra, dosimetric account of the Intrabeam system is rather complex. Skin dose monitoring in IORT is important due to the high dose prescription per treatment fraction. In this study, modeling of the x-ray source and related applicators were performed using the Monte Carlo N-Particle transport code. The dosimetric characteristics of the model were validated against measured data obtained using an ionization chamber and EBT3 film as dosimeters. By using a simulated breast phantom, absorbed doses to the skin for different combinations of applicator size (1.5-5 cm) and treatment depth (0.5-3 cm) were calculated. Simulation results showed overdosing of the skin (>30% of prescribed dose) at a treatment depth of 0.5 cm using applicator sizes larger than 1.5 cm. Skin doses were significantly increased with applicator size, insofar as delivering 12 Gy (60% of the prescribed dose) to skin for the largest sized applicator (5 cm diameter) and treatment depth of 0.5 cm. It is concluded that the recommended 0.5-1 cm distance between the skin and applicator surface does not guarantee skin safety and skin dose is generally more significant in cases with the larger applicators.

    HIGHLIGHTS: • Intrabeam x-ray source and spherical applicators were simulated and skin dose was calculated. • Skin dose for constant skin to applicator distance strongly depends on applicator size. • Use of larger applicators generally results in higher skin dose. • The recommended 0.5-1 cm skin to applicator distance does not guarantee skin safety.

  16. Heavy metals in human teeth dentine: A bio-indicator of metals exposure and environmental pollution
    Asaduzzaman K, Khandaker MU, Binti Baharudin NA, Amin YBM, Farook MS, Bradley DA, et al.
    Chemosphere, 2017 Jun;176:221-230.
    PMID: 28273529 DOI: 10.1016/j.chemosphere.2017.02.114
    With rapid urbanization and large-scale industrial activities, modern human populations are being increasingly subjected to chronic environmental heavy metal exposures. Elemental uptake in tooth dentine is a bioindicator, the uptake occurring during the formation and mineralization processes, stored to large extent over periods of many years. The uptake includes essential elements, most typically geogenic dietary sources, as well as non-essential elements arising through environmental insults. In this study, with the help of the Dental Faculty of the University of Malaya, a total of 50 separate human teeth were collected from dental patients of various ethnicity, age, gender, occupation, dietary habit, residency, etc. Analysis was conducted using inductively coupled plasma-mass spectrometry (ICP-MS), most samples indicating the presence of the following trace elements, placed in order of concentration, from least to greatest: As, Mn, Ba, Cu, Cr, Pb, Zn, Hg, Sb, Al, Sr, Sn. The concentrations have been observed to increase with age. Among the ethnic groups, the teeth of ethnic Chinese showed marginally greater metal concentrations than those of the Indians and Malays, the teeth dentine of females generally showing greater concentrations than that of males. Greater concentrations of Hg, Cu and Sn were found in molars while Pb, Sr, Sb and Zn were present in greater concentrations in incisors. With the elevated concentration levels of heavy metals in tooth dentine reflecting pollution from industrial emissions and urbanization, it is evident that human tooth dentine can provide chronological information on exposure, representing a reliable bio-indicator of environmental pollution.
  17. Reply to Comment on 'Environmental monitoring through the use of silica-based TLD'
    Siti Rozaila Z, Khandaker MU, Abdul Sani SF, Sabtu SN, Amin YM, Maah MJ, et al.
    J Radiol Prot, 2018 12;38(4):1535-1543.
    PMID: 30089707 DOI: 10.1088/1361-6498/aad917
  18. Assessment of radioactivity contents in bedrock groundwater samples from the northern region of Saudi Arabia
    Almasoud FI, Ababneh ZQ, Alanazi YJ, Khandaker MU, Sayyed MI
    Chemosphere, 2020 Mar;242:125181.
    PMID: 31671301 DOI: 10.1016/j.chemosphere.2019.125181
    Recognizing the vast uses of water in human life, the presence of α and β particles emitting radionuclides in groundwater of northern Saudi Arabia has been evaluated as a means of water quality assessment of the region. A liquid scintillation counting technique was used to determine the gross α/β, and 228Ra radioactivities in water samples, while the radioactivity concentrations of 234,238U and 226Ra were determined using alpha spectrometry after the separation process. Present results show that all water samples contain a higher level of gross α and β radioactivity than the WHO recommended limits; the average gross α activity is about 7 times greater than the limit value of 0.5 Bq L-1, while the average gross β activity value is about 3.5 times greater than the limit value of 1 Bq L-1. Correlations of TDS and pH with gross α and β radioactivity in the studied samples were investigated. The activity ratio of the measured U and Ra alpha emitters to the gross α radioactivity and the ratio of the measured β emitters to gross β radioactivity were also discussed. Furthermore, interesting information on thorium abundance and radioactive disequilibrium in U series were observed by studying the activity ratio of 228Ra/226Ra, 226Ra/238U, and 234U/238U. Although these samples are not directly used for human being drinking, and mainly used in irrigation, the higher gross α/β radioactivity may cause health risks to humans, since these radionuclides may enter the food chain through irrigation water. Thus, further radioactive risk assessment is highly recommended.
  19. Study of Primordial 226Ra, 228Ra, and 40K Concentrations in Dietary Palm Dates and Concomitant Radiological Risk
    Khandaker MU, Shuaibu HK, Alklabi FAA, Alzimami KS, Bradley DA
    Health Phys, 2019 06;116(6):789-798.
    PMID: 30889102 DOI: 10.1097/HP.0000000000001042
    The presence of natural radionuclides in the food chain point to a need to assess concentration levels and concomitant radiological risk. Highly popular and forming a staple part of the diet in North Africa, the Arabian Peninsula, and West Asia, palm dates growing naturally there have even greater marketability than simple satisfaction of domestic demand, the palm dates representing a valuable export item. Accurate knowledge of the levels of natural radioactivity in the fruit is thus of importance. In this study, using high-purity germanium gamma-ray spectrometry, quantification has been made of natural radionuclide concentrations in imported dates originating from Iran, Saudi Arabia, and Tunisia. Sample analyses reveal respective mean activity concentrations of 1.4 ± 0.3, 0.8 ± 0.4, and 186 ± 9 Bq kg dry weight for Ra, Ra, and K. For each nuclide, the mean concentration varies little between the dates of the three represented regions. The estimated committed effective dose resulting from the consumption of date fruits for a typical adult was found to be 29.9 μSv y, well below the global internal dose of 290 μSv y assessed by the United Nations Scientific Committee on the Effects of Atomic Radiation to be due to food and water intake. Similarly, the excess lifetime cancer risk due to naturally occurring radioactive material exposure via date fruit consumption is seen to be below the International Commission on Radiological Protection cancer risk factor of 2.5 × 10 based on the additional annual dose limit of 1 mSv for a member of the general public. The results show no significant uptake in the analyzed date fruits.
  20. Raman spectroscopy and X-ray photo-spectroscopy analysis of graphite media irradiated at low doses
    Bradley DA, Siti Rozaila Z, Khandaker MU, Almugren KS, Meevasana W, Abdul Sani SF
    Appl Radiat Isot, 2019 May;147:105-112.
    PMID: 30852298 DOI: 10.1016/j.apradiso.2019.02.016
    We explore the utility of controlled low-doses (0.2-100 Gy) of photon irradiation as initiators of structural alteration in carbon-rich materials. To-date our work on carbon has focused on β-, x- and γ-irradiations and the monitoring of radiotherapeutic doses (from a few Gy up to some tens of Gy) on the basis of the thermoluminescence (TL) signal, also via Raman and X-ray photo-spectroscopy (XPS), providing analysis of the dose dependence of single-walled carbon nanotubes (SWCNT). The work has been extended herein to investigate possibilities for analysis of structural alterations in graphite-rich mixtures, use being made of two grades of graphite-rich pencil lead, 8H and 2B, both being in the form produced for mechanical pencils (propelling or clutch pencils). 2B has the greater graphite content (approaching 98 wt %), 8H being a mixture of C, O, Al and Si (with respective weight percentages 39.2, 38.2, 9.8 and 12.8). Working on media pre-annealed at 400 °C, both have subsequently been irradiated to penetrating photon-mediated doses. Raman spectroscopy analysis has been carried out using a 532 nm laser Raman spectrometer, while for samples irradiated to doses from 1 to 40 Gy, XPS spectra were acquired using Al Kα sources (hv ∼1400 eV); carbon KLL Auger peaks were acquired using 50 eV Pass Energy. At these relatively low doses, alterations in order-disorder are clearly observed, defect generation and internal annealing competing as dominating effects across the dose range.
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