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Journal of Environmental Sciences 2014年第2期26卷 458-465页

作者： Ashok Kumar Chakraborty md.Emran hossain md.Masudur Rhaman K M A Sobahan Department of Applied Chemistry and Chemical Technology Islamic University Department of Applied Physics Electronics and Communication Engineering Islamic University

A nanoheterojunction composite photocatalyst Bi2O3/TiO2 working under visible-light （λ≥ 420 nm） was prepared by combining two semiconductors Bi2O3 and TiO2 varying the Bi2O3/TiO2 molar ratio. Maleic acid was employed as an organic binder to unite Bi2O3 and TiO2 nanoparticles. The SEM, TEM, XRD and diffuse reflectance spectra were utilized to characterize the prepared Bi2O3/TiO2 nanoheterojunction. The nanocomposite exhibited unusual high photocatalytic activity in decomposing 2-propanol in gas phase and phenol in aqueous phase and, evolution of CO2 under visible light irradiation while the end members exhibited low photocatalytic activity. The composite was optimized to 5 mol% Bi2O3/TiO2. The remarkable high photocatalytic efficiency originates from the unique relative energy band position of Bi2O3 and TiO2 as well as the absorption of visible light by Bi2O3.

关键词： nanoheterojunction Bi2O3/TiO2 composite photocatalyst pollutants visible-light

Wildfire in Australia during 2019-2020, Its Impact on Health, Biodiversity and Environment with Some Proposals for Risk Management: A Review

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Journal of Environmental Protection 2021年第6期12卷 391-414页

作者： md. Kamrul Haque md. Abul Kalam Azad md. Yeamin hossain Tareq Ahmed Minhaz Uddin md. Mukhtar hossain Department of Crop Science and Technology University of Rajshahi Rajshahi Bangladesh Department of Fisheries Faculty of Agriculture University of Rajshahi Rajshahi Bangladesh Department of Plant Pathology and Seed Science Sylhet Agricultural University Sylhet Bangladesh School of Environmental Science and Engineering Tianjin University Tianjin China

Wildfire is closely associated with human society and having its effect on earth as well as on its environment for more than 350 million years. It is a very common phenomenon from the ancient period, has hazardous effects on both environment and human life. This study mainly focuses on the review of wildfire of Australia during 2019-2020 regarding its distribution, status of fatality influences on different environmental factors, consequences and some proposals for its mitigation. In this review paper, a modified edition of the principled review methodology was followed in compiling the most reliable data to support the bushfire in Australia belonging to its causes of occurrences and impacts. The bushfire was started in mid-June in 2019, and it is still now burning in hundreds of places of different parts of Australia, and the forest of New South Wales, Northern Territory, Western Australia, Queensland and Victoria were being burnt deadly. The accumulating data exposed the year 2019 as the driest and warmest year with lowest rainfall that might be the potential causes of bushfires in Australia. Moreover, maximum forest land of Australia is covered by naturally grown Eucalyptus trees which are generally flammable and supply oil type fuel during bushfires. Bushfire deteriorates the quality of soil, water and air of the locality up to many hundreds or thousands of kilometers away in increasing the emission of toxic substances and carbon rate. Around more than 3 billion native vertebrates, 143 million mammals, 2.46 billion reptiles, 181 million birds, 51 million frogs were burnt out by bushfires of 2020 in Australia. More than US$110 billion financial loss has been determined due to this fire of Australia. In some cases, it is also helpful for forest land. Sometimes it helps to continue the forest ecosystem by burning unwanted plants, animals and microscopic compounds. To reduce the hazard needs proper land regulation, combination of social governance, sufficient fundin

关键词： Temperature Rainfall Human Health Biodiversity Environmental Effects

Investigation of phase-change materials for interior temperature regulation in public transport

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Clean Energy 2022年第1期6卷 178-192页

作者： md.Nahidul Islam md.Nahid hossain Dewan HasanAhmed Department of Mechanical and Production Engineering Ahsanullah University of Science and Technology141-142 Love RoadTejgaon Industrial AreaDhakaBangladesh

Regulating the indoor temperature of public transport on hot sunny days is a prime concern,as both the external and internal heat sources play an active role in heat *** studies have been carried out on a bus model using sodium sulphate decahydrate as a phase-change material(PCM)that is placed in between the ceiling and the *** are conducted on a sunny day and also for different cases of external(300-W surface heater)and internal(25-W light bulb)heat *** results show that PCM,in the presence of an external heat source,can help to keep the indoor temperature lower and delay the time period for increasing the temperature by absorbing heat during the phase *** the other hand,the presence of the internal heat source contributes to a detrimental effect on the indoor temperature,which gradually increases with the elapse of *** the combination of the external and internal heat sources,it is found that the internal heat source plays a dominating factor to raise the indoor *** is revealed from the experimental results that a 12.7-mm single layer and a single PCM are not enough to counter the internal heat of 25 W unless the thickness of the PCM layer is increased to delay the increase in the indoor *** additional PCM layer with a lower melting temperature could be placed at the inner portion of the ceiling to have effective thermal-energy storage by absorbing the substantial heat gain from the internal heat sources.

关键词： latent heat sodium sulphate decahydrate phase-change material transportation thermal-energy storage

Salt-Induced Changes in Physio-Biochemical and Antioxidant Defense System in Mustard Genotypes

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Phyton-International Journal of Experimental Botany 2020年第3期89卷 541-559页

作者： md.Shakhawat hossain md.Daud hossain Abdul Hannan Mirza Hasanuzzaman md.Motiar Rohman Central Laboratory Research WingBangladesh Agricultural Research InstituteGazipur 1701Bangladesh Seed Technology Division Bangladesh Agricultural Research InstituteGazipur 1701Bangladesh Department of Agronomy Sher-e-Bangla Agricultural UniversityDhaka 1207Bangladesh Molecular Breeding Lab Plant Breeding DivisionBangladesh Agricultural Research InstituteGazipur 1701Bangladesh

Salinity stress is a major factor limiting plant growth and productivity of many crops including *** present study investigated the identification of salt tolerant mustard genotypes and better understanding the mechanism of salinity *** stresses significantly reduced relative water content(RWC),chlorophyll(Chl)content,K^(+) and K^(+)/Na^(+) ratio,photosynthetic rate(P N),tran-spiration rate(Tr),stomatal conductance(gs),intercellular CO_(2) concentration(Ci)and increased the levels of proline(Pro)and lipid peroxidation(md.)contents,Na+,superoxide(O_(2)^(•−))and hydrogen peroxide(H_(2)O_(2))in both tolerant and sensitive mustard *** tolerant genotypes maintained higher Pro and lower md. content than the salt sensitive genotypes under stress *** activities of superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),glutathione peroxidase(GPX),monodehydroascorbate reductase(md.AR)and dehydroascorbate reductase(DHAR)were increased with increasing salinity in salt tolerant genotypes,BJ-1603,BARI Sarisha-11 and BARI Sarisha-16,but the activities were unchanged in salt sensitive genotype,BARI ***,the increment of ascorbate peroxidase(APX)activity was higher in salt sensitive genotype as compared to tolerant ***,the activ-ities of glutathione reductase(GR)and glutathione S-transferase(GST)were increased sharply at stress conditions in tolerant genotypes as compared to sensi-tive *** accumulation of Pro along with improved physiological and biochemical parameters as well as reduced oxidative damage by up-regulation of antioxidant defense system are the mechanisms of salt tolerance in selected mustard genotypes,BJ-1603 and BARI Sarisha-16.

关键词： Mustard saline sensitivity photosynthesis antioxidants ionic imbalance oxidative stress

In VitroOrganogenesis of Colocasia esculentacv. AntiquorumL.

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American Journal of Plant Sciences 2012年第6期3卷 709-713页

作者： md. Jahangir hossain Bangladesh Agricultural Research Institute Gazipur Bangladesh.

In vitro organogenesis of an upland species of Colocasia esculenta cv. antiquorum L. was examined in relation to different explants like meristem and parenchymatous storage tissues with or without anthocyanin layer, four levels of each of Kn, 2,4-D, NAA and BAP and four incubation environments such as: 1) 16 h 3 Kl light intensity + 24°C ± 2°C;2) 24 h dark + 24°C ± 2°C;3) 24 h dark + 30°C ± 3°C and 4) 12 h diffuse light + 30°C ± 3°C. Only meristems showed proliferation with various degree of intensity both at 16 h 3 Kl light + 24°C ± 2°C and 24 h dark + 24°C ± 2°C conditions and poor response with different levels of Kn + NAA either in light or in the dark. Cultures with NAA + BAP were proliferated very quickly with very high degree of intensity. The cultures under dark did not proliferate for 20 days which upon transfer to light showed high degree of proliferation. Cultures with NAA + BAP formed calluses more pronouncedly at dark than that occurred in the light. Parenchymatous tissues with or without anthocyanin did not proliferate but the tissues with anthocyanin lost pigmentation after 25 - 30 days and turned to grey colour after 50 days while tissues without anthocyanin turned to green colour with shinny pimples indicating that protocorm may be developed. No culture under high temperature environment (30°C ± 3°C) neither survived nor proliferated. The meristems in culture were died within 15 - 20 days while others within 25-30 days. In conclusion, a combination of NAA (0.5 - 3.0 mg/l) and BAP (0.5 - 2.0 mg/l) and an incubation photoperiod of 16 h coupled with temperature of 24°C ± 2°C were found most suitable for in vitro culture of Colocasia esculenta cv. antiquorum L.

关键词： Organogenesis Auxin Cytokinin Meristem Parenchymatous Storage Tissue In Vitro Colocasia esculenta cv. Antiquorum L

Vector Autoregressive （VAR） Modeling and Projection of DSE

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Chinese Business Review 2015年第6期14卷 273-289页

作者： Ahammad hossain md. Kamruzzaman md. Ayub Ali Varendra University Rajshahi Bangladesh University of Rajshahi Rajshahi Bangladesh

In this paper, vector autoregressive （VAR） models have been recognized for the selected indicators of Dhaka stock exchange （DSE）. Bangladesh uses the micro economic variables, such as stock trade, invested stock capital, stock volume, current market value, and DSE general indexes which have the direct impact on DSE prices. The data were collected for the period from June 2004 to July 2013 as the basis on daily scale. But to get the maximum explorative information and reduction of volatility, the data have been transformed to the monthly scale. The outliers and extreme values of the study variables are detected through box and whisker plot. To detect the unit root property of the study variables, various unit root tests have been applied. The forecast performance of the different VAR models is compared to have the minimum residual. Moreover, the dynamics of this financial market is analyzed through Granger causality and impulse response analysis.

关键词： vector autoregressive (VAR) model impulse response analysis Granger causality

ARIMA With GARCH Family Modeling and Projection on Share Volume of DSE

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Economics World 2015年第4期3卷 171-184页

作者： Ahammad hossain md. Kamruzzaman md. Ayub Ali Varendra University Rajshahi Bangladesh University ofRajshahi Rajshahi Bangladesh

A suitable statistical model has been explored for the investors as well as the researchers to resolve the future estimation of share volume by using daily stock volume data from Dhaka Stock Exchange （DSE）. The daily volume data from the June 1, 2004 to April 19, 2010 were retrieved from DSE website as a secondary data source. The Maximum Likelihood---Autoregressive Conditional Heteroskedasticity （ARCH）（Marquardt） method has been applied to construct the models for the stock volume data of DSE by using statistical package software E-Views of verson-5. First of all, an ＂Auto Regressive Integrated Moving Average （ARIMA） model＂ was fitted and observed that heteroscedastic volatilities were still present there. To eliminate this dilemma, ARCH class of volatility models has been used and finally the ARIMA with EGARCH model has been explored. Findings of this study have recognized that ARIMA with EGARCH model implies low mean square error, low mean absolute error, low bias proportion, and low variance proportion for share volume data with comparing to other models. Hence, the modelling concept established in this study would be a decisive study for the investors as well as the researchers.

关键词： ARIMA Generalized ARCH (GARCH) family models stock volume projection strategy

Econometric Investigation of DSE＇s Portfolios through Selective Micro and Macro Economic Indicators

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Journal of Statistical Science and Application 2016年第3期4卷 144-153页

作者： Ahammad hossain md. Kamruzzaman md. Ayub Ali PhD Fellow Institute of Bangladesh Studies University of Rajshahi Bangladesh. Associate Professor Institute of Bangladesh Studies University of Rajshahi Bangladesh. Professor Department of Statistics University of Rajshahi Bangladesh.

This paper examines the impact of the portfolios of Dhaka Stock Exchange （DSE） with corresponding to the selective macro and micro economic indicators of Bangladesh. The microeconomic indicators are Invested Market Capital （1MC）（US$） and the number of Total Enlisted Company （TEC） which have direct and immediate impact on the Stock Turnover Ratio （STR） of DSE and the macroeconomic indicators are Gross Domestic Product （GDP）, Gross National Income （GNI）, Gross Saving （GS）, Gross Inflation （GI）, Deposit Interest Rate （DIR）, and Gross Foreign Investment （GFI） which have indirect and long run impact on DSE portfolios. To investigate the direct impact on DSE＇s turnover ratio, the Cobb-Douglas production function is applied and to investigate the indirect and long run impact, multiple linear regression models are also applied. The estimated results are diagnosed using magnitudes of derivatives, gradient and Wald＇s coefficient restriction with respect to the macro and micro economic indicators.

关键词： Direct and immediate impact Indirect and long run impact magnitudes of derivatives gradient andWald's coefficient restriction

Effects of Hall Current and Ohmic Heating on Non-Newtonian Fluid Flow in a Channel due to Peristaltic Wave

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Applied Mathematics 2020年第4期11卷 292-306页

作者： md. Maruf Hasan md. Abdus Samad md. Mubarak hossain Department of Mathematics Comilla University Cumilla Bangladesh Department of Applied Mathematics University of Dhaka Dhaka Bangladesh

In this paper, the study of non-Newtonian fluid flow with heat transfer in a porous asymmetric channel due to peristaltic wave was taken out. Hall current and Ohmic heating effects were introduced in the present study. A Casson non-Newtonian constitutive model was employed for the transport of fluid. Analytical solutions were obtained for stream function, temperature and heat transfer coefficient. The coupled nonlinear equations have also been solved numerically using MATLAB software (by bvp4c function). The influences of many evolving parameters on the flow characteristic have been explained with the help of 2D and 3D plots. Again the obtained results were compared with the results available in the literature and were found in good agreement.

关键词： Ohmic Heating Non-Newtonian Fluid Temperature Field

Efficient Finite Difference Methods for the Numerical Analysis of One-Dimensional Heat Equation

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Journal of Applied Mathematics and Physics 2023年第10期11卷 3099-3123页

作者： md. Shahadat hossain Mojumd.r md. Nazmul Haque md. Joni Alam Department of Mathematics Comilla University Kotbari Bangladesh Department of Mathematical Sciences Kent State University Kent OH USA

In this paper, we investigate and analyze one-dimensional heat equation with appropriate initial and boundary condition using finite difference method. Finite difference method is a well-known numerical technique for obtaining the approximate solutions of an initial boundary value problem. We develop Forward Time Centered Space (FTCS) and Crank-Nicolson (CN) finite difference schemes for one-dimensional heat equation using the Taylor series. Later, we use these schemes to solve our governing equation. The stability criterion is discussed, and the stability conditions for both schemes are verified. We exhibit the results and then compare the results between the exact and approximate solutions. Finally, we estimate error between the exact and approximate solutions for a specific numerical problem to present the convergence of the numerical schemes, and demonstrate the resulting error in graphical representation.

关键词： Explicit Scheme Implicit Scheme C-N Scheme CFL Condition