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Faced with starvation and malnutrition, Spirulina may be considered an alternative potential food supplement in developing countries like Bangladesh. Building on the safety and broadly accepted use of algae as an alternative food resource in Bangladesh, this study aimed to evaluate the willingness to pay (WTP) for three kinds of algae food products: Spirulina tablet/capsule, Spirulina powder, and Spirulina supplement foods. A survey was conducted through online and in-person interviews among Bangladeshi adults by using contingent valuation (CV) method. The surveyor collected socio-demographic characteristics, knowledge, uses, acceptance, and attribute preference of Spirulina as a food supplement. Statistical tool ANOVA was executed to analyze and identify the influencing factors of Spirulina as a future food supplement. Among the 3000 respondents surveyed, 1533 (51.11%) stated that they would accept Spirulina as a food supplement, while others would accept Spirulina as a tablet/capsule (15.64%) and powder (33.43%), respectively. The average WTPs of Spirulina tablet/capsule, powder, and supplement are estimated to be US$ 4.18, US$ 3.66, and US$ 4.8, respectively. To introduce Spirulina food products in Bangladesh as a practical importance for the industrial production of algae-based food supplements, we present positive and welcoming public attitudes towards new food products that are safe, healthy, and affordable.

Background and Objective: In addition to the reduction of risk of COVID-19 transmission and mortality, vaccination and compliance with the preventive measures of COVID-19 may have important additional benefits for the improvement of mental health. This study examined the levels and determinants of vaccination, compliance with preventive measures, and anxiety, depression and stress among Bangladeshi adults. It also examined the effects of vaccination and compliance with preventive measures on mental health status among Bangladeshi adults. Methods: Data for the study come from an online survey conducted during November and December 2021 among Bangladeshi adults. A total of 615 adults participated in the survey. A 21-item Depression, Anxiety, and Stress scale (DASS 21) were used for collecting data on mental health. Both descriptive and inferential statistical methods including multiple logistic regression were used for data analysis. Results: About 69% of Bangladeshi adults were vaccinated with at least one dose; 87% of adults believed that vaccines are moderate to highly effective in reducing COVID-19 infection. Among the preventive measures during a pandemic, the level of complete compliance with wearing masks and hand washing was almost universal, while the compliance level with other preventive measures was moderate. Vaccinated people had a 55% (OR=0.45; 95%CI:0.26-0.82), 67% (OR=0.33; 95%CI:0.12-0.91), and 44% (OR=0.56; 95%CI:0.27-0.97) lower chance of suffering from depression, anxiety, and stress, respectively than non-vaccinated people. People with complete compliance had 64% (OR= 0.36; 95%CI:0.18-0.72), 71% (OR=0.29; 95%CI:0.15-0.58), and 74% (OR=0.26; 95%CI:0.13-0.50) lower risk of suffering from depression, anxiety, and stress, respectively, than respondents with irregular preventive behaviors. Conclusion: This study documents the important psychological benefits of vaccination and compliance with preventive measures of COVID-19.

The majority of the resources used for producing energy are conventional, which are limited and diminish quickly. So, it's critical to find out alternative options for energy generation. The wind, which is the cleanest and most accessible renewable energy source generated by highway vehicles, is completely wasted. A vertical axis wind turbine (VAWT) may use this energy to generate electricity and store it in a battery if needed. The turbine shaft is connected to the U-coupler through the bearing, and the coupler is then connected to the motor shaft, which generates electricity. Here, we have harnessed electricity using VAWT, which could be installed on highway dividers in Bangladesh. We have produced an open circuit voltage of ~10 V by a 12 V, 200 rpm DC motor at a cut-in speed of 2.3 ms^−1. The generated power is fed to charge a mobile phone indicating a constant electrical power supply.

Activated carbon signifies extensive carbonized materials of a high degree of porosity and has a wide range of applications. The porous and thermal properties of activated carbon (AC) are primarily...

This paper presents a rigorous exergy analysis of a vapor compression refrigeration system (VCRS) for the AHRI standard cooling operating conditions assessed with a constant cooling load of 50 kW. A comprehensive mathematical model has been developed to evaluate thermodynamic variables of the major components. The analysis is carried out for widely used refrigerants, namely R12, R22, R134a, R152a, R410A; next-generation low GWP refrigerants R32, R1234yf, R1234ze(E); and two natural refrigerants R600a and R744 (CO2). First law analysis and exergetic efficiency at cycle and component level are investigated for all the refrigerants. The results indicate that R600a is the best, followed by R152a, R1234ze(E), and R1234yf in terms of COP, total exergy destruction, and exergetic efficiency. Moreover, the total equivalent warming impact (TEWI), which is the aggregation of direct impact due to refrigerant leakage and indirect impact due to electricity usage, from each system has also been assessed. The lowest and highest amount of TEWI has been found for R600a and R12 systems, respectively. CO2 is an extremely prospective refrigerant for its lower emission, affordability, availability, non-toxicity, non-flammability, and system compactness when the MVRS is driven by electricity from nuclear/renewable sources.

Graphene exhibits great mechanical, electrical, and optical properties, making it an imperative material to use as a window layer in a thin-film solar cell. The efficiency and fill factor of the Cu_2ZnSnS_4 (CZTS) solar cell are increased owing to the incorporation of graphene. Numerical modeling and Solar Cell Capacitance Simulator (SCAPS)-1D simulation have been explored on an efficient CZTS based thin-film solar cell via simulating the proposed structure (Graphene/ZnO/CZTS/Ni) to obtain a nature-friendly solar cell. Besides, the effects of the absorber layer’s properties on cell performance parameters have been analyzed. In the proposed cell, the number of layers has been optimized using highly transparent graphene to reach enough sunlight intensity to the absorber layer and back contact. This paper also revealed the effect of temperature and found higher stability in the proposed cell. The optimized cell attributes V_oc=0.85 V and J_sc=23.815 mAcm^−2, FF=84.68%, η=17.14%.

The incapability of people to have sufficient access to energy sources is known as energy poverty. It is a multi-faceted and complex problem. This research looks into how renewable energy use, economic growth, urbanization, employment, and the consumer price index are all linked to energy poverty in South Asian nations. The relationship between the analyzed factors in this region has not been thoroughly investigated so far. As a result, the goal of this research is to look at the dynamic relationships between these variables in the most energy-intensive countries of South Asia using advanced econometric methods for the years 2000 to 2020. This analysis imply that renewable energy reduces energy poverty. Furthermore, energy poverty is inversely correlated with economic growth and employment, but positively associated with urbanization. The findings provide a foundation for energy policymakers that would help them to achieve the objective of Sustainable Development Goals (SDGs).

This study explores how economic development in South Asian countries could be boosted by recognizing potential of digital innovation, and ensuring energy efficiency in an age of digital economy. The relationship between digitalization, energy intensity, and economic growth in South Asian economies has not been well investigated. As a result, the goal of this research is to use advanced econometric approaches to analyze the relationship between these variables for the period of 1995- 2018. The findings imply that digitization boosts economic growth in the countries investigated. Furthermore, energy intensity is inversely related to economic growth. In policy perspective, this study argues that leveraging the benefits of digital innovation in the energy sector will improve long-term economic performance.

Biomass energy consumption has become a popular issue among policymakers in recent years due to its environmental repercussions. Biomass is one of the most common traditional easy sources of energy, and various studies have demonstrated its effects to health and the economy. However, there is a paucity of evidence on the use of biomass energy to mitigate climate change. This study explores the relationship between biomass energy consumption and ecological footprint in Bazil, Russia, India, China and South Africa (BRICS) countries during the period of 1990-2017. For this purpose, we employed augmented mean group (AMG) panel data estimator addressing the heterogeneity and problem of cross-sectional dependency in the panel data series. The results indicate that biomass energy consumption raises the ecological footprint of the BRICS nations. Policies are proposed to reduce the negative impact of biomass energy on the environment based on these findings.

Hybrid renewable energy system (HRES) is an evolving power generation strategy that requires a combination of various energy resources and is common in modern pursuits. Allowing features, such as low CO2 emissions, less environmentally damaging possibilities than traditional power generation techniques, and mostly unlimited power resources give more flexibility. Along with connecting these HRES power plants with the national grid for the addition of more power generation, electrification of remote areas is possible with stand-alone power plants. The proposed research model is a quantitative study on the potentiality of renewable sources in St. Martin's Island, a geographically important location of Bangladesh. This work incorporates solar, wind, and biomass sources in the HRES system, which is a relatively new concept when compared with other HRES strategies with a levelized cost of $0.18. An enhanced HRES model is proposed considering different constraints revealing a new possibility of power generation on that island.

Arsenic poisoning has been a great concern for the last two decades because of its extensive problems. Coagulation, ion exchange, ultrafiltration, and adsorption systems have been used for the removal of arsenic from polluted water. In this study, the biosorption process was used owing to eco-friendly, simplicity, biodegradable, and cost effectiveness. The uptake of arsenic from contaminated water by Ulva lactuca, Spirulina platensis, Chlorella vulgaris, orange peel, NZVI, zeolite, and composite of NZVI and algae was studied. This study observed that Chlorella vulgaris and iron coated Chlorella vulgaris absorb arsenic more effectively than other algae and iron coated algae. After 24 hours, Chlorella vulgaris and Fe-coated Chlorella vulgaris absorbs 23% and 67% arsenic from contaminated water, respectively. The presented findings depicted the great potential of using bio-sorbents and the Fe-algae bio-composite for the removal of arsenic from contaminated aqueous solutions.

While the accumulation of arsenic in rice (Oryza sativa L.) has been highlighted as a major concern in Bangladesh, sustainable measures are critically needed to reduce the uptake of arsenic by rice plants. In the present study, a pot-experiment was conducted using a Boro rice variety (BRRI dhan-29) in two geomorphologically different soils from Holocene floodplains and Pleistocene terraces, in which silicon-rich fresh rice husk (FRH) and rice husk ash (RHA) were applied, as silicon fertilisers, in the soils at the rate of 1% (w/w) of rice residue:soil.In the Holocene floodplain soils, the application of FRH was found to decrease arsenic in grain, husk and straw by 42, 56 and 51%, respectively, whereas the soil incorporation of RHA decreased arsenic in grain, husk and straw by 26, 37.5 and 36%, respectively. In the Pleistocene terrace soils, the application of FRH reduced the grain, husk and straw arsenic by 38, 38 and 44%, respectively, whereas the RHA decreased the grain, husk and straw arsenic by 26, 30 and 29%, respectively. Fresh rice husk was found to be more effective in alleviating arsenic accumulation in rice than RHA. In both the Holocene floodplain and Pleistocene terrace soils, the grain concentrations of calcium, phosphorus, silicon, and zinc were found to be increased with the decrease of arsenic in the grain due to the use of FRH and RHA. The present study suggests that silicon-rich rice husk residue scan be used as silicon fertilisers to reduce arsenic accumulation in rice in Bangladesh. Bangladesh J. Sci. Ind. Res.56(3), 195-206, 2021

Carbon emissions and excessive power usage are addressed by applying thermoelectric cooling, which benefits from its ability to be portable, economical, and reliable. However, a conventional thermoelectric air conditioner's coefficient of performance (COP) is much less due to the sustained heat generated on the thermoelectric module's hot side. This work presents a novel idea of utilizing a nanofluid cooled radiator as an external cooling jacket around the thermoelectric module's hot side to enhance the heat transfer rate of thermoelectric air conditioners. In this research, the performance of a newly designed thermoelectric air conditioner (TEAC) powered by photovoltaic systems (PV) installed in a residential building is analyzed using nanofluid as a coolant. Furthermore, by supplying different input currents (2-6A), the cooling characteristics and performance of the newly designed nanofluid assisted thermoelectric air conditioner (NTEAC) system were experimentally studied in a test room of 25.6 m3 volume in Malaysia's tropical climate. The system's best performance was at 6A, with a maximum temperature drop of 4.9 °C, a cooling capacity of 571 W, and a coefficient of performance of 1.27. In addition, the NTEAC system showed an energy saving of 67% and CO2 emission mitigation of 76% when compared with a conventional split air conditioner. Thus, an alternative to the traditional air conditioning system was developed from this research, which is Freon free. This system is expected to consume less energy and emit less CO2 for the tropical climatic conditions.

In this study, effects of bloodmeal on onion (Allium cepa L. CV. BARI peaj-1) cultivation to increase yield and related attributes have been tested. The effect of blood meal as fertilizers has been compared with growth hormone treatment and other conventional fertilizer. In the field, the different amount of growth elements treated were at the rate of 2550, 241.90 and 0.17 kg/ha for blood meal, urea and gibberellic acid (GA3), respectively. The yield performance was 172.84, 189.59 and 153.34 MT/ha for GA3, urea and blood meal, respectively. Using GA3 is expensive, and use of urea, a chemical fertilizer, can have adverse effect on soil. Blood meal, a biological ingredient, appears to be a bio-rationale amendment for production and sustained yield of onion. The results will need to ground truth tested in the field. Bangladesh J. Sci. Ind. Res.56(2), 87-94, 2021

Maxsorb III is the best available microporous activated carbon. The parent Maxsorb III has been modified by pyrolysis in the presence of ammonia carbonate. The adsorption isotherms and kinetics of HFC404A onto the modified Maxsorb III are experimentally measured over 25 °C to 75 °C. Toth and Dubinin-Astakhov models are utilized to fit the experimentally measured data. The isosteric heat of adsorption is calculated by applying the Clausius-Clapeyron equation. The adsorption kinetics of the modified Maxsorb III/HFC404A are fitted using the linear driving force model and Fickian Diffusion equation. Experimental measurements indicate that the modified Maxsorb III has a maximum uptake of 2.65 kg.kg−1 of HFC404A at 25 °C, which is the highest reached value till today. Additionally, the adsorption cooling system efficacy is evaluated under typical operating conditions using the modified Maxsorb III/HFC404A pair. The modified Maxsorb III/HFC404A could achieve a specific cooling power (SCP) of 747 W per kg of adsorbent along with a coefficient of performance (COP) of 0.40. Compared to the parent Maxsorb III/HFC404A pair, the pyrolyzed Maxsorb III/HFC404A pair provides the SCP and COP by a factor of 2.23 and 1.7, respectively, which are are the current benchmark.

The effective removal of strontium from polluted water is an emerging issue worldwide, especially in Japan, after the destruction of Fukushima’s Daiichi Nuclear Power Plant. In the strontium removal process, statistical optimization of associated factors is needed to reduce the quantity of chemicals and the number of experimental trials. In this study, response surface methodology based on the central composite design was employed for assessing the influence of different factors and their interaction effects on the efficiency of strontium removal. We have considered nanoscale zero-valent iron-zeolite (nZVI-Z) and nano-Fe/Cu zeolite (nFe/Cu-Z) as adsorbents for the effective removal of strontium. The results suggested that the studied three factors such as pH, contact time, and concentration are positively related to the adsorption of strontium. That is, the maximum strontium removal occurred at pH, initial concentration, and contact time of 12, 200 mg L−1, and 30 min, respectively. The experimental maximum strontium adsorption capacity of nZVI-Z and nFe/Cu-Z adsorbents is 32.5 mg/g and 34 mg/g, respectively. The present study also showed that the most statistically significant potential contributor was initial concentration, followed by contact time in the removal process. The study indicated that the interaction effect between contact time and initial concentration was statistically important, suggesting the need for a multi-mechanism technique in the removal phase of strontium. Tόth, Langmuir, Dubinin-Astakhov (D-A), Freundlich, and Hill isotherm models were also fitted with the experimental strontium adsorption data, in which the Tόth model fitted best compared to the other models based on the RMSD and R2.

The measurement of electrical power and efficiency of a thermoelectric generator (TEG) holds significant importance in the realm of thermoelectric materials research and development. The present investigation involves the measurement of thermoelectric characteristics, namely electrical conductivity, Seebeck coefficient, and thermal conductivity, of cement composites containing graphene nanoplatelets and metallic oxides (Fe2O3, ZnO, MnO2). These properties are then utilized to determine the electrical power output and efficiency of the aforementioned composites. It is possible to estimate a power output of up to 1.5 W per square meter when utilizing GnP-ZnO-added cement composites, given a temperature differential of approximately 50 °C. This paper additionally discusses the methodology for fabricating a cement composite-based structural TEG module with the aim of augmenting the overall output voltage, power, and efficiency of the system.

This study was conducted to assess the accumulation and sources of harmful metals and associated public health risk from the usage of underground mine water of Barapukuria coal mine in Bangladesh, keeping in mind the optimum reuse. Thirty underground mine water samples had been analyzed for assessing temperature, pH, EC, TC, DO, BOD, COD, Ca, K, S, Ti, Mn, V, Fe, Co, Ni, Cu, Zn, Br, Rb, Sr, and Pb. Numerous pollution evaluation and health risk assessment indices along with multivariate statistical tools were employed in this study to apprise the pollution scenario, controlling factors, and probable health risk. The chronic or persistent health risk of metals via oral and dermal exposure of adults and children was determined using the hazard quotient (HQ) and hazard index (HI). The results showed that the content of physicochemical parameters and potentially harmful elements in water samples was many folds higher than the national and international standards. The results of pollution evaluation indices indicate that coal seam-leached mine water is highly concentrated by potentially harmful metals and not suitable for drinking, agriculture, and aquatic lives. The correlation coefficients and multivariate analysis illustrate both the geological and anthropogenic factors controlling the variability of metals in mine water. Results of HQoral value suggest that V, Co, and Pb are significant health risk for adults and Mn, V, Co, Cu, and Pb are for children. Vanadium is found potential for dermal effects, and HIdermal value directs 33%, and 70% samples exceed the safe limit for adults and children, respectively. The HI value suggests that oral exposure to harmful metals creates more harm than dermal absorption, and children are more vulnerable than adults. It is anticipated that the outcomes of this study would deliver expedient insights to initiate necessary steps to minimize the public health risk by applying appropriate environmental protocols.

Mangroves play a vital role in protecting the coastal community from the climate change effect and in the restoration of the coastal ecosystem. This research has been designed to determine the spatial and seasonal changes of potentially toxic elements' (PTEs) concentration in sediments and their potential source contribution among the different human-driven processes in Sundarbans, Bangladesh. Different pollution evaluation indices, random forest (RF) model, conditional inference tree (CIT), self-organizing map (SOM), geographical information system (GIS), and principal component analysis (PCA) were used for the interpretation of sources and risk assessment of PTEs. The mean concentration of PTEs both in winter and monsoon seasons has fallen below the threshold effect level but exceeded the rare effect level of marine sediments quality standards. Results showed that the PTEs were significantly enriched (EF 1.00 70.00) in sediments, whereas the Cd enrichment (7.00% samples) was very alarming (EF = 60-70). Except for Zn and Cd, other PTEs were enriched in 30-60% samples. The highest geoaccumulation and contamination factors for Cd were observed in 46-72% of samples. The ecological risk (ER) factors showed similar results where Cd showed strong to very strong factors (ER = 110-2218) in 80% of samples. The CIT explained the natural/geogenic and anthropogenic sources of pollution, where the higher CIT values for Cd indicated industrial, aquaculture, and coal-based thermal powerplant. The RF model provided that shrimp firms, power plants, industry, and seaport were recognized as the influential sources for Zn, Pb, Cr, Cd, and As in sediments. Though Pb and As were found as the most significant pollutants, Cd was identified as a severe threat to ecology and public health. Based on CIT, RF, SOM and PCA the order of PTEs in mangroves sediment were:industrial/urban aquaculture/shrimpfirm powerplant seaportoperation tourism geogenic/natural. The present study will help the policymakers for effective and sustainable management of the mangrove ecosystem.

This work comes as a part of a series of researches carried out by our team to study and present new materials with distinctive properties suitable for adsorption applications. As we previously studied employment of many Freons within the adsorption cooling systems, this paper expresses a study using HFC404A with activated carbon (Maxorb III). Adsorption of Maxsorb III/HFC404A pair has been estimated experimentally at different temperatures ranging from 25 to 75 °C. Dubinin-Astakhov (D-A) and Toth equations have been fitted with the experimental data to evaluate the adsorption isotherm, while the adsorption kinetic is evaluated by linear driving force model (LDF) and Fickian diffusion (FD) equations. The maximum adsorption capacity is 2.2 kg R404A/kg activated carbon. The numerical values of the activation energy (Ea) and the pre-exponential coefficient (Dso) are evaluated to be 3429.27 kJ/kg and 5.35×10–13, respectively. Transient simulation modeling has been carried out to predict performance of adsorption cooling system under different operating temperatures of Maxsorb III/HFC404A. Optimum recorded coefficient for performance and specific cooling power is 0.23 and 275 W/kg, respectively.

Conventional surfactants such as CTAB (cetrimonium bromide), SDS (sodium dodecyl sulphate), SDBS (sodium dodecyl sulphonate) are combined with nanofluids to improve the stability and thermal conductivity of nanofluids. These nanofluids are mainly used for heat transfer applications where heating and cooling are usual courses of action which result in surfactants producing foams and polluting the heat transfer media, affecting the total system performance. Besides, the common surfactant molecules that augment the thermal resistance between the nanoparticles and base fluid also affect the thermophysical properties of the nanofluid. In this paper, [Bmim][Cl] (1-butyl-3-methylimidazolium chloride), a high purity ionic liquid (IL) with higher thermal stability was used to provide a comparative study on the stability and thermal properties with that of the conventional surfactants (CTAB, SDS, SDBS) on multiwalled carbon nanotubes (MWCNT)/propylene glycol (PG) nanofluid. The transient hot-wire based KD2-Pro and zeta potential results demonstrated that the inclusion of ionic liquid improved the thermal conductivity and stability of the formulated nanofluid. However, much like the conventional surfactants, the strong electrostatic repulsive force created by the ionic liquid was found to decrease when the temperature is increased. The outcome demonstrated the most extreme thermal conductivity upgrade of 33.7% at 303 K and maximum dispersion stability of more than one month without any aggregation for the nanofluid containing ionic liquid.