Atomic Energy Center Dhaka

Dhaka, Bangladesh

Atomic Energy Center Dhaka

Dhaka, Bangladesh
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Islam M.A.,Bangladesh Institute of Technology | Al-mamun A.,Khulna University | Hossain F.,Jessore University of Science and Technology | Quraishi S.B.,Atomic Energy Center Dhaka | And 6 more authors.
Marine Pollution Bulletin | Year: 2017

In this study, total concentrations of 16 trace elements (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sb, Hg, Pb, Th and U) in sediments of the rivers of the Sundarban mangrove forest, after the catastrophic oil spill accident in the Sela river of Sundarban, were determined. The overall mean concentrations of V, Cr, Fe and Cd in surface sediments of the Sundarban are remarkably higher than available literature data of those elements. Trace element contamination assessment, using different environmental contamination indices, reveals that As, Sb, Th and U are low to moderately contaminated while Cd is moderately to severely contaminated in the sediments of this area. The multivariate statistical analyses were applied to reveal the origin and behavior of the elements during their transport in the mangrove ecosystem. High Cr, Ni, Cu and As concentrations suggest the risk of potentially adverse biological effects in the ecosystem. © 2017 Elsevier Ltd.

Rahman M.M.,Murdoch University | Jiang Z.-T.,Murdoch University | Munroe P.,University of South Australia | Chuah L.S.,Universiti Sains Malaysia | And 11 more authors.
RSC Advances | Year: 2016

Transition metal nitride TixM1-x-yNy (M = Al or AlSi) based thin films are evaluated as solar selective surfaces by correlating their spectral selective features with their crystal structure and chemical bonding state including mechanical strength. Ti0.5N0.5, Ti0.25Al0.25N0.5, and Ti0.25Al0.2Si0.05N0.5 films were synthesized on AISI M2 steel substrates via closed field unbalanced magnetron sputtering technology. These were investigated using XRD, SEM, XPS, UV-Vis, FTIR and nanoindentation techniques. Analysis of the optical properties showed the solar absorptance, in the visible range, of the TixM1-x-yNy films improved significantly from 51% to 81% with AlSi-doping and an increase of solar absorptance of up to 66% was recorded from films doped with Al. Moreover, the Al doping can reduce the thermal emittance in the infrared range from 6.06% to 5.11%, whereas doping with AlSi reduces the emittance to ca. 3.58%. The highest solar selectivity of 22.63 was achieved with TiAlSiN films. Mechanical studies showed enhanced hardness by ∼32%; enhanced yield strength by ∼16% and enhanced plastic deformation by ∼110% of Al and AlSi doped TiN matrix. © 2016 The Royal Society of Chemistry.

Ashraf M.A.,Bangladesh University | Bhuiyan A.H.,Bangladesh University of Engineering and Technology | Hakim M.A.,Atomic Energy Center Dhaka | Hossain M.T.,BCSIR Laboratories
Physica B: Condensed Matter | Year: 2010

The microstructure and electrical properties of Ho2O3 doped Bi2O3-based ZnO varistor ceramics were investigated. The bulk density varies between 5.41 and 5.47 g cm-3 with the maximum value of 5.47 g cm-3 for 0.50 mol% Ho 2O3 content. The average grain size for all the samples was calculated from the scanning electron micrographs and were found between 5.1 and 7.1 μm. The microstructure of the prepared samples shows a decrease in grain size of ZnO phase with Ho2O3 doping. The energy dispersive X-ray analysis and X-ray diffraction analysis of the samples show the presence of ZnO, Bi-rich, spinel Zn7Sb2O12 and Ho2O3-based phases. The nonlinear coefficient, α, obtained from electric fieldcurrent density plots has a maximum value of 78 for the ceramics with 0.50 mol% Ho2O3 content. The leakage current, IL, has a minimum value of 1.30 μA for the 0.50 mol% Ho2O3 doped ZnO varistor ceramics. The breakdown field, Eb, was found to increase with Ho2O3 content. © 2010 Elsevier B.V. All rights reserved.

Uddin Md.N.,Shahjalal University of Science and Technology | Islam Md.S.,Shahjalal University of Science and Technology | Islam Md.S.,Kumamoto University | Mazumder Md.M.R.,Shahjalal University of Science and Technology | And 8 more authors.
Journal of Inclusion Phenomena and Macrocyclic Chemistry | Year: 2015

Thin films of TiO2 and B/N/Ag co-doped carbon nanotube (CNT)-TiO2 (Ag/B/N-CNT-TiO2) composite on top of glass substrates have been successfully prepared by a simple sol-gel drop coating route. The films were characterized by X-ray diffraction (XRD) and UV-Vis spectroscopy. XRD patterns of TiO2, CNT-TiO2 and co-doped TiO2 composite films were shown single phase of anatase. The UV-Vis absorption spectra showed absorption edge shifted to visible light region after doping Ag/B/N in TiO2. The photocatalytic properties of Ag/B/N-CNT-TiO2 thin films were evaluated by degradation of methylene blue under visible light irradiation. It has been found that photocatalytic efficiency was significantly improved when TiO2 is subjected to modify by using Ag, B, N and CNT. The highest photocatalytic activity has been shown by 2 %B/5 %N-CNT-TiO2 with 58 % efficiency whereas the efficiency was only 17 % for pure TiO2 film. The experimental photodegradation data were well fitted by zero-order, first-order and modified Freundlich kinetic models. The antimicrobial activities of the prepared composite thin films have also been tested using bacteria Escherichia coli (E. coli). The composite Ag-TiO2 and 2 %B/5 %N/2 %Ag-CNT-TiO2 showed higher antimicrobial activity than B/N-CNT-TiO2. All of the thin films have been used in many times for the degradation measurement and antibacterial studies. © 2015 Springer Science+Business Media.

Ashraf M.A.,Bangladesh University | Bhuiyan A.H.,Bangladesh University of Engineering and Technology | Hakim M.A.,Atomic Energy Center Dhaka | Hossain M.T.,Bangladesh Council of Scientific and Industrial Research BCSIR
Materials Science and Engineering B: Solid-State Materials for Advanced Technology | Year: 2011

The dependence of the bulk density, microstructure and dc electrical properties of bismuth oxide (Bi2O3)-based zinc oxide (ZnO) varistor ceramics for various samarium oxide (Sm2O3) contents was investigated. The value of bulk density was found to 5.43-5.50 g cm-3 with Sm2O3 (mol%) content. The maximum value of bulk density is observed to be 5.50 for 0.30 mol% Sm2O 3 containing varistor ceramics. The grain sizes for all the samples calculated from the scanning electron micrographs were found to decrease as Sm2O3 increases. The presence of ZnO phases, Bi-rich phases, spinel phases and Sm2O3 phases were observed in the samples by the energy dispersive X-ray analysis and X-ray diffraction analysis. As the Sm2O3 amount increased in the Bi 2O3-based ZnO varistor ceramics, the nonlinear coefficient, α increased up to 0.10 mol%, reaching a maximum value of 58 and then decreased. The breakdown electric field, Eb, increased with the increase of Sm2O3 content with a maximum value of 3220 V cm-1 for the 0.75 mol% Sm2O3 doped ZnO varistor ceramics. The leakage current, IL, showed a minimum value of 1.10 μA for the composition of 0.30 mol% Sm2O3 doped Bi2O3-based ZnO varistor ceramics. The 0.30 mol% Sm 2O3-doped Bi2O3-based ZnO varistor ceramics sintered at 1200 °C exhibited a good stability for dc accelerated aging stress of 0.90 V1 mA/90 °C/12 h. © 2011 Elsevier B.V. All rights reserved.

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