Noakhali Science and Technology University
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

Khan M.A.R.,Noakhali Science and Technology University | Rahman M.M.,Universiti Malaysia Pahang
International Journal of Advanced Manufacturing Technology | Year: 2017

A large number of parameters significantly affect the performance of electrical discharge machining (EDM) which is a non-conventional technique. The choice of the EDM parameters depends on workpiece-electrode material combination. So, the selection of parameters becomes intricate. This manuscript presents the surface characteristics of the machined surface in EDM on Ti-5Al-2.5Sn titanium alloy. The surface roughness and the microstructure of the machined surface are explored for different EDM parameters and electrode materials. Experimentation was accomplished using negative polarity of copper, copper-tungsten and graphite electrode. In this study, peak current, pulse-on time, pulse-off time and servo-voltage are taken into consideration as process variables. The surface roughness is greatly influenced by peak current and pulse-on time among the selected electrical parameters. Among the three electrodes, the copper electrode produces the lowest surface roughness whilst graphite electrode gives the highest surface roughness. The surface characteristics (crater, crack and globule) are distorted on account of discharge energy. In context of fine surface characteristics, the copper can become as first choice electrode materials. © 2017 Springer-Verlag London

Hossain M.S.,Noakhali Science and Technology University | Banik S.,Noakhali Science and Technology University | Islam M.S.,Noakhali Science and Technology University
Indian Journal of Pharmaceutical Education and Research | Year: 2012

The purpose of the present study was to formulate sustained release Trimetazidine Dihydrochloride matrix tablets by using Kollidon SR as rate controlling polymer. Each of the formulated tablet contains 35 mg of Trimetazidine Dihydrochloride. The tablets were prepared by direct compression method. The granules were evaluated for angle of repose, bulk density, tapped density and compressibility index. The formulated tablets were evaluated for weight variation, thickness, diameter, hardness, friability and drug content and also in-vitro dissolution studies. Drug content in formulation was determined by UV method. The granules showed satisfactory flow properties. All the tablet formulations showed acceptable pharmacotechnical properties and complied for tested parameters. The in-vitro release study of matrix tablets were carried out in phosphate buffer with pH 7.4 for 7 hours. The drug release from each formulation was analyzed by using release kinetic theories. The results of dissolution studies indicated that all the formulations exhibited drug release pattern very close to theoretical release profile. Applying kinetic equation models, the mechanism of release of the drug from all the formulations were found to be followed Higuchi model, as the plots showed high linearity, with correlation coefficient (r 2) value of 0.93 or more. The 'n' value lies between 0.45

Sarwar M.S.,Noakhali Science and Technology University | Hossain M.S.,Noakhali Science and Technology University
Brazilian Journal of Pharmaceutical Sciences | Year: 2012

The present study was undertaken to develop sustained release (SR) matrix tablets of losartan potassium, an angiotensin-II antagonist for the treatment of hypertension. The tablets were prepared by direct compression method, along with Kollidon SR as release retardant polymer. The amount of losartan potassium remains fixed (100 mg) for all the three formulations whereas the amounts of Kollidon SR were 250 mg, 225 mg, and 200 mg for F-1, F-2, and F-3 respectively. The evaluation involves three stages: the micromeritic properties evaluation of granules, physical property studies of tablets, and in-vitro release kinetics studies. The USP apparatus type II was selected to perform the dissolution test, and the dissolution medium was 900 mL phosphate buffer pH 6.8. The test was carried out at 75 rpm, and the temperature was maintained at 37 °C ± 0.5 °C. The release kinetics was analyzed using several kinetics models. Higher polymeric content in the matrix decreased the release rate of drug. At lower polymeric level, the rate and extent of drug release were enhanced. All the formulations followed Higuchi release kinetics where the Regression co-efficient (R2) values are 0.958, 0.944, and 0.920 for F-1, F-2, and F-3 respectively, and they exhibited diffusion dominated drug release. Statistically significant (P<0.05) differences were found among the drug release profile from different level of polymeric matrices. The release mechanism changed from non-fickian (n=0.489 for F-1) to fickian (n=0.439 and 0.429 for F-2, and F-3 respectively) as a function of decreasing the polymer concentration. The Mean Dissolution Time (MDT) values were increased with the increase in polymer concentration.

Saha M.R.,Noakhali Science and Technology University | Debnath P.C.,Noakhali Science and Technology University | Rahman M.A.,University of Rajshahi | Islam M.A.U.,University of Rajshahi
Bangladesh Journal of Pharmacology | Year: 2012

This present study explored the anthelmintic activities of crude methanolic extract of dried leaves and stems of Justicia gendarussa, an evergreen plant belonging to the family Acanthaceae. This plant is commonly known as Bishjarul in Bangladesh. Five concentrations (10, 20, 30, 40 and 50 mg/mL) of each extract were studied in the bioassay to determine the paralysis time and death time of the worm, Pheretima posthuma. Methanolic extract of leaves (50 mg/mL) caused paralysis of the worms at 35.33 min and death at 70.67 min while methanolic extract of stem of J. gendarussa caused paralysis at 41.33 min and death at 89.33 min. Albendazole (positive control) paralyzed and killed the worms at 17 min and 48 min, respectively. The study confirms the significant anthelmintic activities of leaves and stems extract of J. gendarussa and therefore demands the isolation of active principles thorough bioassay. This is the first report of anthelmintic activities of J. gendarussa.

Ghosh A.,Noakhali Science and Technology University | Banik S.,Noakhali Science and Technology University | Islam M.A.,Noakhali Science and Technology University
Bangladesh Journal of Pharmacology | Year: 2015

Xanthium indicum is an important medicinal plant traditionally used in Bangladesh as a folkloric treatment. The current study was undertaken to evaluate thrombolytic, anthelmintic, anti-oxidant, cytotoxic properties with phytochemical screening of methanolic extract of X. indicum leaves. The analysis of phytochemical screening confirmed the existence of phytosetrols and diterpenes. In thrombolytic assay, a significant clot lysis was observed at four concentrations of plant extract compare to the positive control streptokinase (30,000 IU, 15,000 IU) and negative control normal saline. The extract revealed potent anthelmintic activity at different concentrations. In anti-oxidant activity evaluation by two potential experiments namely total phenolic content determination and free radical scavenging assay by 2, 2- diphenylpicrylhydrazyl (DPPH), the leaves extract possess good anti-oxidant property. In the brine shrimp lethality bioassay, the crude extract showed potent (LC50 1.3 μg/mL) cytotoxic activity compare to the vincristine sulfate as a positive control (LC50 0.8 μg/mL). © 2015, Bangladesh Pharmacological Society. All rights reserved.

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.

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.

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