Fakruddin M.,Bangladesh Institute of Technology |
Mannan K.S.B.,Center for Food and Waterborne Diseases |
Mazumdar R.M.,BCSIR Laboratories Chittagong |
Afroz H.,Primeasia University
BMC Complementary and Alternative Medicine | Year: 2012
Background: There is wide spread interest in drugs derived from plants as green medicine is believed to be safe and dependable, compared with costly synthetic drugs that have adverse effects.Methods: We have attempted to evaluate the antioxidant, In vitro thrombolytic, antibacterial, antifungal and cytotoxic effects of Clausena heptaphylla (Rutaceae) stem bark extract ethanol extract.Results: Ethanolic stem bark extract of Clausena heptaphylla (CHET) contains flavonoids, alkaloids, saponins and steroids but it lacks tannins, anthraquinones and resins. Phenol content of the extract was 13.42 mg/g and flavonoid content was 68.9 mg/g. CHET exhibited significant DPPH free radical scavenging activity with IC50 value of 3.11 μg/ml. Reducing power of CHET was also moderately stronger. In the cytotoxicity assay, LC50 and Chi-square value of the ethanolic extract against brine shrimp nauplii were 144.1461 μg/ml and 0.8533 demonstrating potent cytotoxic effect of the extract. In vitro thrombolytic activity of CHET is significant with 45.38% clot lysis capability compared to that of Streptokinase (65.78%). In antibacterial screening, moderate zone of inhibition (6.5-9.0 mm in diameter) was observed against gram-positive Bacillus subtilis ATCC 11774, Bacillus cereus ATCC 10876, Staphylococcus aureus ATCC 25923, Bacillus polymyxa ATCC 842 and Bacillus megaterium ATCC 13578 and less promising zone of inhibition (3.0-4.5 mm in diameter) against gram-negative Salmonella typhi ATCC 65154, Shigella flexneri ATCC 12022, Proteus vulgaris ATCC 13315 and Escherichia coli ATCC 25922. Shigella sonnei ATCC 8992 did not show any sensitivity. The MIC values against these bacteria were ranged from 2,000 to 3,500 μg/ml. The extract showed significant zone of inhibition against Rhizopus oryzae DSM 2200, Aspergillus niger DSM 737 and Aspergillus ochraceus DSM 824 in antifungal assay.Conclusions: Further advanced research is necessary to isolate and characterize the chemical components responsible for the therapeutic properties of the plant. © 2012 Fakruddin et al.; licensee BioMed Central Ltd.
Van Maren D.S.,Deltares |
Van Maren D.S.,Technical University of Delft |
Liew S.C.,National University of Singapore |
Hasan G.M.J.,Shahjalal University of Science and Technology |
Hasan G.M.J.,Bangladesh Institute of Technology
Continental Shelf Research | Year: 2014
In past decades, the turbidity in Singapore's coastal waters has been increased. This has led to reduced visibility and increased siltation rates, detrimental for the coral reefs and other sensitive ecosystems around Singapore. The reasons for this increased turbidity are poorly known because little quantitative information exists on sediment dynamics around Singapore, on changes in sediment sources, and on the physical environment. Therefore we set out to quantify the effect of fluvial contributions on changes in sediment dynamics, using a combination of numerical models, satellite images, and hydrodynamic and sedimentary data. Results indicate that the main fluvial source enters an ebb-dominant estuary, with sediment export primarily balanced by settling/scour lags rather than estuarine circulation. A large part of the sediment load enters the Singapore Strait, where the large-scale marine currents effectively transport most sediment towards the coral reefs. However, mixing with marine water masses in both the estuary and the adjacent Singapore Strait sufficiently dilutes this fluvial sediment source to have a negligible impact on Singapore's coral reefs. © 2013 Elsevier Ltd.
Sanjidah S.,Bangladesh Institute of Technology
2nd International Conference on Electrical Engineering and Information and Communication Technology, iCEEiCT 2015 | Year: 2015
A framework for analyzing the effect of a non uniform source/drain (S/D) doping profile on triangular tri-gate FinFET considering the compact modeling is presented. This paper demonstrates a fully physical model for triangular tri-gate leakage distribution due to variation of S/D doping. Fixed S/D doping can remarkably suppress short channel effect which is responsible for sub-threshold conduction. The proposed model predicts that the non uniform doping increases short channel effect as well as sub-threshold conduction and due to which a large increase in leakage current is obtained. We also investigated the impact of S/D doping on geometrical parameters such as fin height and fin width. Using Monte Carlo simulation a random variation of leakage current associated with parameter variation can be found that also predicts the dependency of leakage current on threshold voltage. © 2015 IEEE.
Zebin T.,Bangladesh Institute of Technology |
Alam M.S.,University of Dhaka
Journal of Computers | Year: 2012
Flexible manipulator systems exhibit many advantages over their traditional (rigid) counterparts. However, they have not been favored in production industries due to its obvious disadvantages in controlling the manipulator. This paper presents theoretical investigation into the dynamic modeling and characterization of a constrained two-link flexible manipulator, by using finite element method. The final derived model of the system is simulated to investigate the behavior of the system. A Genetic Algorithm (GA) based fuzzy logic control strategy is also developed to reduce the end-point vibration of a flexible manipulator without sacrificing its speed of response. An uncoupled fuzzy logic controller approach is employed with individual controllers at the shoulder and the elbow link utilizing hub-angle error and hub-velocity feedback. GA has been used to extract and optimize the rule base of the fuzzy logic controller. The fitness function of GA optimization process is formed by taking weighted sum of multiple objectives to trade off between system overshoot and rise time. Moreover, scaling factors of the fuzzy controller are tuned with GA to improve the performance of the controller. A significant amount of vibration reduction has been achieved with satisfactory level of overshoot, rise time and settling time and steady state error. © 2012 ACADEMY PUBLISHER.
Ahiduzzaman M.,Bangladesh Institute of Technology |
Islam A.K.M.S.,Islamic University of Technology
Renewable and Sustainable Energy Reviews | Year: 2011
Bangladesh is an energy starving country. The country will be on one of the fast growing power markets with its population and growing energy demand per person, its fast growing urbanization, and its socio-economic development. At present the potential demand of power is 5569 MW and the supply is below 4000 MW. The country is dependent on the imported petroleum that is big burden on the economy. The per capita emission is only 0.2667 tonne per person still much below the world leading countries (19.8 tonne per person for USA). However, Bangladesh is one of the most vulnerable to climate change effect in the world. In this regard, renewable energy resources appear to be the one of the most efficient and effective solution for clean and sustainable energy development in Bangladesh. Biomass is the dominating source of energy in Bangladesh. Biomass energy is used in a very traditional way. Biomass conversion to energy in the form of liquid, gaseous and solid pellet or briquette could be a viable option to reduce the pressure on the conventional fossil fuel. The geographical location of Bangladesh has several advantages for extensive use of grid connected solar electricity and stand alone solar PV system. This article presents a review of the potential and utilization of the renewable energy sources in Bangladesh. © 2011 Elsevier Ltd. All rights reserved.