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Rājshāhi, Bangladesh

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.

Islam F.,University of Rajshahi | Islam F.,Griffith University | Khanam J.A.,University of Rajshahi | Khatun M.,University of Rajshahi | And 8 more authors.
Phytotherapy Research | Year: 2015

Anticancer activities of p-menth-1-ene-4,7-diol (EC-1) isolated from Eucalyptus camaldulensis Dhnh. were studied on Ehrlich ascites carcinoma (EAC) cells by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. Anticancer activities also analyzed in EAC-bearing mice by assessment of cancer growth inhibition, changes in cancer volume, changes in life span, and hematological parameters. Apoptosis was analyzed by fluorescence microscope, DNA fragmentation assay, and flow cytometry. The expression of apoptosis-related genes, Bcl-2, Bcl-X, PARP-1, p53, and Bax, were analyzed using polymerase chain reaction (PCR). EC-1 significantly inhibited proliferation of EAC cells in vivo and restored the altered hematological parameters of EAC-bearing mice. Cytological observation by fluorescence microscope showed apoptosis of EAC cells upon treatment with EC-1. Also, DNA fragmentation assay revealed EAC cells' apoptosis following EC-1 treatment. Increased mRNA expressions of p53 and Bax genes and negative expressions of Bcl-2 and Bcl-X were observed in cells treated with EC-1. These findings confirmed the induction of apoptosis by EC-1. In addition, MTT assay showed dose-dependent anticancer activity of EC-1 against EAC cell. Cell cycle analysis revealed that EC-1 treatment caused suppression of EAC cells at S phase. To conclude, EC-1 is a novel anticancer compound and showed antiproliferative and apoptotic activities in cellular and mice models. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Talukder A.I.,University of Dhaka | Sultana P.,University of Dhaka | Haider A.F.M.Y.,University of Dhaka | Wahadoszamen M.,University of Dhaka | And 2 more authors.
European Physical Journal D | Year: 2010

Silver nanoparticles have been produced by laser ablation of silver metal in nanopure water without any chemical additives. It has been observed that laser power has a control over the size of the nanoparticles. Increasing laser power shows a clear blue shift in the absorption peak of fabricated nanoparticles indicating that the average size of the particles decreases with increasing laser power. Ablation for longer period reduces the average size of nanoparticles which is attributed to the re-ablation of fabricated nanoparticles. A good correlation has been observed between the peak of the absorption spectrum measured by UV-VIS spectroscopy and the average particle size measured by scanning electron microscope imaging method. The value of the coefficient of correlation is determined to be 0.965. © 2010 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

Islam M.R.,Bangladesh University of Engineering and Technology | Podder J.,Bangladesh University of Engineering and Technology | Farhad S.F.U.,BCSIR Laboratories | Saha D.K.,Atomic Energy Center
Sensors and Transducers | Year: 2011

Nano fiber ZnO films have been deposited on to glass substrate at 200 °C by a simple spray pyrolysis technique under atmospheric pressure. The effect of annealing temperature on the structural and optical properties of the as grown films has been studied by Scanning Electron Microscopy (SEM) attached with an EDX, powder X-ray diffraction and UV visible spectroscopy. The atomic weight % of Zinc and Oxygen were found to be 49.22 % and 49.62 % respectively. The SEM micrographs show nano fiber structure and uniform deposition on the substrate. Average grain size of ZnO thin film was found in the range of 21 to 27 nm. The lattice constant a and c of ZnO thin film are determined at different annealing temperatures and values are found slightly larger than those of JCPDS data and lower for the sample annealed at 600 °C. The lattice parameters a and c decrease with increasing temperature. It reveals that the samples are poly-crystalline and having with low densities. Band gap energy of ZnO was found in the range of 3.33 to 3.17 eV and decreases with the increase of the annealing temperature. © 2011 IFSA.

Sarker M.S.R.,University of Dhaka | Alam M.Z.,University of Dhaka | Qadir M.R.,Pilot Plant & Project Development Center & | Gafur M.A.,Pilot Plant & Project Development Center & | Moniruzzaman M.,BCSIR Laboratories
International Journal of Minerals, Metallurgy and Materials | Year: 2015

A significant amount of aluminum dross is available as a waste in foundry industries in Bangladesh. In this study, alumina was extracted from aluminum dross collected from two foundry industries situated in Dhamrai and Manikgang, near the capital city, Dhaka. Aluminum dross samples were found to approximately contain 75wt% Al2O3 and 12wt% SiO2. An acid dissolution process was used to recover the alumina value from the dross. The effects of various parameters, e.g., temperature, acid concentration, and leaching time, on the extraction of alumina were studied to optimize the dissolution process. First, Al(OH)3 was produced in the form of a gel. Calcination of the Al(OH)3 gel at 1000°C, 1200°C, and 1400°C for 2 h produced γ-Al2O3, (α+γ)-Al2O3, and α-alumina powder, respectively. Thermal characterization of the Al(OH)3 gel was performed by thermogravimetric/differential thermal analysis (TG/DTA) and differential scanning calorimetry (DSC). The phases and crystallite size of the alumina were determined by X-ray diffraction analysis. The dimensions of the alumina were found to be on the nano level. The chemical compositions of the aluminum dross and alumina were determined by X-ray fluorescence (XRF) spectroscopy. The microstructure and morphology of the alumina were studied with scanning electron microscopy. The purity of the alumina extracted in this study was found to be 99.0%. Thus, it is expected that the obtained alumina powders can be potentially utilized as biomaterials. © 2015, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

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