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Zakir Hossain H.M.,Jessore University of Science and Technology | Zakir Hossain H.M.,The University of Shimane | Sampei Y.,The University of Shimane | Roser B.P.,The University of Shimane
Organic Geochemistry | Year: 2013

Distribution and possible sources of polycyclic aromatic hydrocarbons (PAHs) have been investigated in 23 late Eocene to early Pleistocene mudstones from the Sylhet succession of the northeastern Bengal Basin, Bangladesh. Paleoclimatic conditions in the southern Himalaya region throughout the Himalayan uplift were reconstructed, based on combustion derived PAHs and aromatic land plant derived biomarkers. Phenanthrene, fluoranthene (Fla), pyrene (Py), benz[a]anthracene (BaAn), chrysene/triphenylene (Chry+Tpn), benzofluoranthenes (Bflas), benzo[e]pyrene (BePy), benzo[a]pyrene (BaPy), perylene (Pery), indeno[1,2,3-cd]pyrene (InPy), benzo[ghi]perylene (BghiP), coronene (Cor) and retene (Ret) were the identified PAHs. Fla/(Fla+Py) ratios>0.5 and InPy/(InPy+BghiP)>0.2 from almost all Sylhet samples suggest occurrence of natural wildfires. Low contents of BaAn and BaPy indicate decomposition by long exposure to sunlight before sedimentation, or early diagenetic weathering. Increased Cor, InPy and BghiP contents suggest occurrence of larger, high temperature wildfires. Correlation coefficients of the PAHs and p-values for statistical hypothesis testing showed that the positive and negative correlations within the PAHs may be indicative of high or low temperatures in wildfires. Fungi derived Pery showed negative correlations with Py (r=-0.67, p=4.6×10-4) and Fla (r=-0.56, p=5.0×10-3), but not with Cor, Bflas, InPy and BghiP. Based on the correlation coefficients for all PAHs and their p-values, five statistical groups ([Py, Fla], [Cor, Bflas, InPy, BghiP], [BaAn, Chry+Tpn, BaPy], [Pery] and [Ret]) were recognized. These groups are probably correlated with origins and depositional processes. According to the results, the Sylhet succession was deposited in three differing paleoclimatic regimes: (1) First phase (late Eocene to early Miocene, early to middle stage of Himalayan uplift): High contents of combustion derived PAHs (Fla, Py and BePy), significant gymnosperm derived Ret, and low Pery abundances in the Jaintia and Barail groups indicate arid climatic conditions. Although wildfires could often occur, 5- or 6-ring combustion PAHs (Cor, InPy and BghiP) contents are low, suggesting that the wildfires were relatively low temperature. (2) Second phase (middle to late Miocene: middle to late stage of Himalayan uplift): Combustion derived PAHs and fungi derived Pery were dominant in the Surma Group. The climate was arid to humid and seasonal, with a dry season giving conditions suitable for combustion. Abundant Fla, Bflas, BePy, Cor, InPy and BghiP imply high temperatures in large wildfires. However, frequency of the wildfires decreased because of wet climate. (3) Third phase (late Miocene to Pleistocene: late stage of Himalayan uplift): Moderate to high Pery contents and low Fla, Py and BePy abundances in the Tipam and Dupitila groups indicate establishment of more humid climate. InPy, BghiP, Cor, Bflas and BaPy were predominant. Intensified humid and seasonal climate arising from the Himalayan monsoon decreased the incidence and frequency of general wildfires, but increased the ratio of large to small wildfires. © 2012 Elsevier Ltd. Source


Jahid I.K.,Chung - Ang University | Jahid I.K.,Jessore University of Science and Technology | Lee N.-Y.,Chung - Ang University | Kim A.,Chung - Ang University | Ha S.-D.,Chung - Ang University
Journal of Food Protection | Year: 2013

Aeromonas hydrophila recently has received increased attention because it is opportunistic and a primary human pathogen. A. hydrophila biofilm formation and its control are a major concern for food safety because biofilms are related to virulence. Therefore, we investigated biofilm formation, motility inhibition, quorum sensing, and exoprotease production of this opportunistic pathogen in response to various glucose concentrations from 0.05 to 2.5% (wt/vol). More than 0.05% glucose significantly impaired (P < 0.05) quorum sensing, biofilm formation, protease production, and swarming and swimming motility, whereas bacteria treated with 0.05% glucose had activity similar to that of the control (0% glucose). A stage shift biofilm assay revealed that the addition of glucose (2.5%) inhibited initial biofilm formation but not later stages. However, addition of quorum sensing molecules N-3-butanoyl-DL-homoserine lactone and N-3-hexanoyl homoserine lactone partially restored protease production, indicating that quorum sensing is controlled by glucose concentrations. Thus, glucose present in food or added as a preservative could regulate acyl-homoserine lactone quorum sensing molecules, which mediate biofilm formation and virulence in A. hydrophila. Copyright ©, International Association for Food Protection. Source


Halder P.K.,Jessore University of Science and Technology | Paul N.,Bangladesh University of Engineering and Technology | Beg M.R.A.,Rajshahi University of Engineering and Technology
Renewable and Sustainable Energy Reviews | Year: 2014

Bangladesh is energy starve country facing a severe power crisis for the last few decades because of inadequate power generation capacity compared with demand. The power generation of the country largely depends on the non-renewable (fossil fuel) energy sources, mainly on the natural gas as accounts 64.5% of recent installed capacity. This trend causes rapid depletion of non-renewable energy sources. Thus, it is necessary to trim down the dependency on non-renewable energy sources and utilize the available renewable resources to meet the huge energy demand facing the country. Most of the people living in rural, remote, coastal and isolated areas in Bangladesh have no electricity access yet. However, renewable energy resources, especially biomass can play a pivotal role to electrify those rural, remote, coastal and isolated areas in the country. Humankind has been using biomass as an energy source for thousands of years. This study assesses the bio-energy potential, utilization and related Renewable Energy Technologies (RETs) practice in Bangladesh. Improved cooking stove, biogas plant and biomass briquetting are the major RETs commonly practiced in Bangladesh. The assessment includes the potential of agricultural residue, forest residue, animal manure and municipal solid waste. The estimated total amount of biomass resource available for energy in Bangladesh in 2012-2013 is 90.21 million tons with the annual energy potential of 45.91 million tons of coal equivalent. The recoverable amount of biomass (90.21 million tons) in 2012-2013 has an energy potential of 1344.99 PJ which is equivalent to 373.71 TWh of electricity. © 2014 Elsevier Ltd. Source


Jahid I.K.,Chung - Ang University | Jahid I.K.,Jessore University of Science and Technology | Ha S.-D.,Chung - Ang University
Foodborne Pathogens and Disease | Year: 2014

The present article focuses on the inactivation kinetics of various disinfectants including ethanol, sodium hypochlorite, hydrogen peroxide, peracetic acid, and benzalkonium chloride against Aeromonas hydrophila biofilms and planktonic cells. Efficacy was determined by viable plate count and compared using a modified Weibull model. The removal of the biofilms matrix was determined by the crystal violet assay and was confirmed by field-emission scanning electron microscope. The results revealed that all the experimental data and calculated Weibull α (scale) and β (shape) parameters had a good fit, as the R2 values were between 0.88 and 0.99. Biofilms are more resistant to disinfectants than planktonic cells. Ethanol (70%) was the most effective in killing cells in the biofilms and significantly reduced (p<0.05) the biofilms matrix. The Weibull parameter b-value correlated (R2=0.6835) with the biofilms matrix removal. The present findings deduce that the Weibull model is suitable to determine biofilms matrix reduction as well as the effectiveness of chemical disinfectants on biofilms. The study showed that the Weibull model could successfully be used on food and food contact surfaces to determine the exact contact time for killing biofilms-forming foodborne pathogens. © 2014 Mary Ann Liebert, Inc. Source


Rahman S.,Jessore University of Science and Technology | Parvin R.,Chittagong Veterinary and Animal Sciences University
Asian Pacific Journal of Tropical Disease | Year: 2014

Medicinal plants are used in herbalism. They form the easily available source for healthcare purposes in rural and tribal areas. In the present review, an attempt has been made to congregate the phytochemical and pharmacological studies done on an important medicinal plant Aegle marmelos. Extensive experimental and clinical studies prove that Aegle marmelos possesses antidiarrhoeal, antimicrobial, antiviral, radioprotective, anticancer, chemopreventive, antipyretic, ulcer healing, antigenotoxic, diuretic, antifertility and anti-inflammatory properties, which help it to play role in prevention and treatment of many disease. Therefore, it is worthwhile to review its therapeutic properties to give an overview of its status to scientist both modern and ancient. This review also encompasses on the potential application of the above plant in the pharmaceutical field due to its wide pharmacological activities. © 2014 Asian Pacific Tropical Medicine Press. Source

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