Chittagong, Bangladesh

Noakhali Science and Technology University is a newly established public university in the coastal terrain Noakhali of Bangladesh. It is the 27th public university and fifth science and technology university in Bangladesh when it established, while in 2013, it places as 10th public university and 2nd science and technology university in national ranking. Its foundation stone was laid on 11 October 2003 and academic activities started on 22 June 2006. Founding a science and technology university in a coastal terrain like Noakhali is significant. A newly accrued coastal system may render this university a versatile field station to study the pattern of changes in the seashore and to harness its opportunities. Wikipedia.

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Lee J.W.,Inha University | Nobi A.,Noakhali Science and Technology University
Computational Economics | Year: 2017

We consider the effects of the 2008 global financial crisis on the global stock market before, during, and after the crisis. We generate complex networks from a cross-correlation matrix such as the threshold network (TN) and the minimal spanning tree (MST). In the threshold network, we assign a threshold value by using the mean and standard deviation of cross-correlation coefficients. When the threshold is equal to the mean of these coefficients, we observe a giant cluster composed of three economic zones in all three periods. We find that during the crisis, the countries in the Asian zone were weakly connected and those in the American zone were tightly linked to the countries in the European zone. At a large threshold, the three economic zones were fragmented. The European countries connected tightly, but the Asian countries bound weakly. The MST constructed from the distance matrix. In the MST, France remained a hub node in all three periods. The size of the MST shrank slightly during the crisis. We observe a scaling relation between the network distance of nodes from the central hub (France) and the geometrical distance. We observe the topological change of the financial network structure during the global financial crisis. The TN and MST are complementary roles to understand the connecting structure of financial complex networks. The TN reveals to observe the clustering effects and robustness of the cluster during the financial crisis. The MST shows the central hub and connecting node among the economic zones. © 2017 Springer Science+Business Media New York

Islam M.S.,Noakhali Science and Technology University | Mostofa A.G.M.,University of Dhaka | Ahmed M.U.,University of Dhaka | Sayeed M.S.B.,The University of Asia Pacific | And 2 more authors.
Tumor Biology | Year: 2014

The rate of direct smoking, second hand smoking, and smokeless tobacco users as well as the amount of environmental pollutant like polycyclic aromatic hydrocarons is increasing in Bangladesh. Therefore, the prevalence of lung cancer is increasing day by day. To the best of our knowledge, no pharmacogentic study of CYP3A4, CYP3A5 genes has been reported on Bangladeshi population relating those with lung cancer. The present study was conducted to determine the association of CYP3A4, CYP3A5 gene polymorphisms and tobacco smoking in the development of lung cancer in Bangladeshi population. A case-control study was carried out on 106 lung cancer patients and 116 controls to investigate three allelic variants - CYP3A4*1B, CYP3A5*3, and CYP3A5*6 using Polymerase Chain Reaction Restriction Fragment Length Polymorphism. Risk of lung cancer was estimated as odds ratio (OR) and 95% confidence interval (CI) using unconditional logistic regression models. The variant allele frequencies for CYP3A4*1B (*1A/*1B+*1B/*1B) were 2.83%and 0.86%and that of CYP3A5*3 (*1A/*3+*3/*3) were 88.68% and 85.34% in cases and controls, respectively. Individual carrying at least one variant allele of CYP3A4*1B (CYP3A4*1A/1B+*1B/1B) has a 3.35 times more risk (OR=3.35, 95% Cl=0.34-32.71, p =0.271) for developing lung cancer whereas individual carrying at least one variant allele of CYP3A5 (CYP3A5*1A/3+*3/3) has a 1.26 times more risk (OR=1.35, 95% Cl=0.61-2.97) and both are statistically non-significant (p >0.05). CYP3A5*6 was absent in the study population. No association of lung cancer with the mentioned polymorphisms was found both in heavy and light smokers. In the cases of all three major types of lung cancer-squamous cell carcinoma, adenocarcinoma, and small cell carcinoma-significantly strong relationships (p 0.05) have been found. To confirm the association of lung cancer with the mentioned polymorphisms, large number volunteers (patients and controls) will be required. © International Society of Oncology and BioMarkers (ISOBM) 2013.

Nobi A.,Inha University | Nobi A.,Noakhali Science and Technology University | Maeng S.E.,Inha University | Ha G.G.,Inha University | Lee J.W.,Inha University
Journal of the Korean Physical Society | Year: 2013

We analyzed cross-correlations between price fluctuations of global financial indices (20 daily stock indices over the world) and local indices (daily indices of 200 companies in the Korean stock market) by using random matrix theory (RMT). We compared eigenvalues and components of the largest and the second largest eigenvectors of the cross-correlation matrix before, during, and after the global financial the crisis in the year 2008. We find that the majority of its eigenvalues fall within the RMT bounds [λ-, λ+], where λ- and λ+ are the lower and the upper bounds of the eigenvalues of random correlation matrices. The components of the eigenvectors for the largest positive eigenvalues indicate the identical financial market mode dominating the global and local indices. On the other hand, the components of the eigenvector corresponding to the second largest eigenvalue are positive and negative values alternatively. The components before the crisis change sign during the crisis, and those during the crisis change sign after the crisis. The largest inverse participation ratio (IPR) corresponding to the smallest eigenvector is higher after the crisis than during any other periods in the global and local indices. During the global financial the crisis, the correlations among the global indices and among the local stock indices are perturbed significantly. However, the correlations between indices quickly recover the trends before the crisis. © 2013 The Korean Physical Society.

Miah M.Y.,Environment Canada | Miah M.Y.,Noakhali Science and Technology University | Volchek K.,Environment Canada | Kuang W.,SAIC | Tezel F.H.,University of Ottawa
Journal of Hazardous Materials | Year: 2010

A series of experiments were performed to quantify the adsorption of cesium on ceiling tiles as a representative of urban construction materials. Adsorption was carried out from solutions to mimic wet environmental conditions. Non-radioactive cesium chloride was used as a surrogate of the radioactive 137Cs. The experiments were performed in the range of initial cesium concentrations of 0.114-23.9mgL-1 at room temperature (21°C) around three weeks. Solution samples were taken after set periods of time and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The quantity of adsorbed Cs was calculated by mass balance as a function of time.Two kinetic and three equilibrium models were employed to interpret the test results. Determination of kinetic parameters for adsorption was carried out using the first-order reaction model and the intra-particle diffusion model. Adsorption equilibrium was studied using Langmuir, Freundlich and three-parameter Langmuir-Freundlich adsorption isotherm models. A satisfactory correlation between the experimental and the predicted values was observed. © 2010.

Volchek K.,Environment Canada | Miah M.Y.,Environment Canada | Miah M.Y.,Noakhali Science and Technology University | Kuang W.,Environment Canada | And 2 more authors.
Journal of Hazardous Materials | Year: 2011

The adsorption of cesium on cement mortar from aqueous solutions was studied in series of bench-scale tests. The effects of cesium concentration, temperature and contact time on process kinetics and equilibrium were evaluated. Experiments were carried out in a range of initial cesium concentrations from 0.0103 to 10.88mgL-1 and temperatures from 278 to 313K using coupons of cement mortar immersed in the solutions. Non-radioactive cesium chloride was used as a surrogate of the radioactive 137Cs. Solution samples were taken after set periods of time and analyzed by inductively coupled plasma mass spectroscopy.Depending on the initial cesium concentration, its equilibrium concentration in solution ranged from 0.0069 to 8.837mgL-1 while the respective surface concentration on coupons varied from 0.0395 to 22.34μgcm-2. Equilibrium test results correlated well with the Freundlich isotherm model for the entire test duration. Test results revealed that an increase in temperature resulted in an increase in adsorption rate and a decrease in equilibrium cesium surface concentration. Among several kinetic models considered, the pseudo-second order reaction model was found to be the best to describe the kinetic test results in the studied range of concentrations. The adsorption activation energy determined from Arrhenius equation was found to be approximately 55.9kJmol-1 suggesting that chemisorption was the prevalent mechanism of interaction between cesium ions and cement mortar. © 2011.

Chowdhury M.M.H.,Noakhali Science and Technology University | Kubra K.,Noakhali Science and Technology University | Ahmed S.R.,Chittagong University
Annals of Clinical Microbiology and Antimicrobials | Year: 2015

Background: For a long time mushrooms have been playing an important role in several aspects of the human activity. Recently edible mushrooms are used extensively in cooking and make part of new food in Bangladesh for their beneficial properties. The aim of this study is to screen some values of mushrooms used in Bangladesh. Methods: Methanolic extracts of 3 edible mushrooms (Pleurotus ostreatus, Lentinula edodes, Hypsizigus tessulatus) isolated from Chittagong, Bangladesh were used in this study. Phenolic compounds in the mushroom methanolic extracts were estimated by a colorimetric assay. The antioxidant activity was determined by radical 1, 1-diphenyl;-2-picrylhydrazyl (DPPH) radical scavenging assay. Eight microbial isolates were used for antimicrobial activity of methanolic extract of mushrooms by the agar well diffusion method with slight modification. Results: Determination of antimicrobial activity indicated considerable activity against all bacteria and fungi reveling zone of inhibition ranged from 7 ± 0.2 to 20 ± 0.1 mm. Minimum inhibitory concentration values of the extracts showed that they are also active even in least concentrations ranged from 1 mg/ml to 9 mg/ml. Lentinula edodes showed the best antimicrobial activity than others. Pseudomonas aeruginosa was quite resistant and Saccharomyces cerevisiae was more sensitive than others microbial isolates. Antioxidant efficiency by inhibitory concentration on 1,1-Diphenly-2-picrylhydrazyl (DPPH) was found significant when compared to standard antioxidant like ascorbic Acid. The concentration (IC50) ranged from 100 ± 1.20 to 110 ± 1.24 μg/ml. Total phenols are the major bioactive component found in extracts of isolates expressed as mg of GAE per gram of fruit body, which ranged from 3.20 ± 0.05 to 10.66 ± 0.52 mg/ml. Average concentration of flavonoid ranged from 2.50 ± 0.008 mg/ml to 4.76 ± 0.11 mg/ml; followed by very small concentration of ascorbic acid (range, 0.06 ± 0.00 mg/ml to 0.21 ± 0.01 mg/ml) in all the isolates. All the isolates showed high phenol and flavonoid content (except Pleurotus ostreatus), but ascorbic acid content was found in traces. Conclusion: This study has revealed that selected edible mushrooms have not only nutritional values but also some therapeutic values. Proper and more investigations can lead us to use these as strong medicine in future. © 2015 Chowdhury et al.

Nobi A.,Inha University | Nobi A.,Noakhali Science and Technology University | Maeng S.E.,Inha University | Ha G.G.,Inha University | Lee J.W.,Inha University
Physica A: Statistical Mechanics and its Applications | Year: 2014

This study considers the effects of the 2008 global financial crisis on threshold networks of a local Korean financial market around the time of the crisis. Prices of individual stocks belonging to KOSPI 200 (Korea Composite Stock Price Index 200) are considered for three time periods, namely before, during, and after the crisis. Threshold networks are constructed from fully connected cross-correlation networks, and thresholds of cross-correlation coefficients are assigned to obtain threshold networks. At the high threshold, only one large cluster consisting of firms in the financial sector, heavy industry, and construction is observed during the crisis. However, before and after the crisis, there are several fragmented clusters belonging to various sectors. The power law of the degree distribution in threshold networks is observed within the limited range of thresholds. Threshold networks are fatter during the crisis than before or after the crisis. The clustering coefficient of the threshold network follows the power law in the scaling range. © 2014 Elsevier B.V. All rights reserved.

Khan M.A.R.,Noakhali Science and Technology University | Rahman M.M.,Universiti Malaysia Pahang | Kadirgama K.,Universiti Malaysia Pahang
International Journal of Automotive and Mechanical Engineering | Year: 2014

The proper selection of machining parameters can result in better machining performance in the electrical discharge machining process. However, this job is not always easy since the phenomena occurring between the electrodes in EDM are not yet fully understood. This study reports the development of a comprehensive mathematical model for the electrode wear rate (EWR) of a graphite tool in EDM on Ti-5Al-2.5Sn alloy, which has not yet been presented. Experiments for positive polarity of the graphite electrode, based on design of experiment (DOE), are first conducted. Modeling and analysis are carried out through the response surface methodology, utilizing the experimental results. A confirmation test is also executed to confirm the validity and the accuracy of the mathematical model developed. The confirmation test exhibits an average error of less than 6%. Negative electrode wear is evidenced for particular settings. The combination of 15A peak current, 350μs pulse-on time, 180μs pulse-off time and 95V servo-voltage and positive polarity causes negative tool wear. It is apparent that the developed model can evaluate electrode wear rate accurately and successfully. © Universiti Malaysia Pahang.

Chowdhury M.M.H.,Noakhali Science and Technology University | Kubra K.,Noakhali Science and Technology University | Ahmed S.R.,Chittagong University
Research Journal of Medicinal Plant | Year: 2014

The search of new antimicrobial agents is a current demand due to emerging resistance of pathogen against the currently available antimicrobial agents. The use of medicinal plants as natural substitute is the paramount area of research to overwhelm the drug resistance of infectious agents. In the present study, antimicrobial activity of Lawsonia inermis was investigated against clinical isolates of eight bacteria including five Gram negative (Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, Klebsiella pneumoniae, Shigella sonnei) and three Gram positive (Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis) using disc diffusion method. Four types of Lawsonia inermis extracts were prepared using methanol, chloroform, acetone and water as extraction solvents while DMSO (Dimethyl sulfoxide) and water as dissolution solvents. The rate and extent of bacterial killing was determined by Time-kill kinetic assay at 1xMIC of each bacterial isolate. The overall safety of Lawsonia inermis extracts was assessed in mice. The minimum value of MIC for different bacterial isolates ranged from 3-9.50 mg mL-1. At 1xMIC of each bacterial isolate, 3log10 decrease in CFU was recorded after 6 h of drug exposure and no growth was observed in all tested bacteria after 24 h of exposure except B. subtilis and S. epidermidis. No sign of toxidrome were observed during in vivo toxicity evaluation in mice at 300 mg kg-1 concentration. The present study provides the scientific rational for medicinal use of Lawsonia inermis. The use of Lawsonia inermis extracts is of great significance as substitute antimicrobial agent in therapeutics. © 2014 Academic Journals Inc.

Rahman Khan Md.A.,Noakhali Science and Technology University | Rahman M.M.,Universiti Malaysia Pahang | Kadirgama K.,Universiti Malaysia Pahang
Procedia Engineering | Year: 2014

The problem appeared owing to selection of parameters increases the deficiency of electrical discharge machining (EDM) process. Modelling can facilitate the acquisition of a better understanding of such complex process, save the machining time and make the process economic. Thus, the present work emphasizes the development of an artificial neural network (ANN) model for predicting the surface roughness (Ra). Trainingandtestingaredonewithdatathatarefoundsucceedingtheexperimentasdesignofexperiments. The surface topography of the machined part was analysed by scanning electronic microscopy. The result shows thatthe ANN model can predict the surface roughness effectively. Low discharge energy level results in smaller craters and micro-cracks producing a suitable structure of the surface. This approach helps in economic EDM machining. © 2014 The Authors. Published by Elsevier Ltd.

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