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"Akhtaruzzaman"
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WS2: A New Window Layer Material for Solar Cell Application
Radio frequency (RF) magnetron sputtering was used to deposit tungsten disulfide (WS
2
) thin films on top of soda lime glass substrates. The deposition power of RF magnetron sputtering varied at 50, 100, 150, 200, and 250 W to investigate the impact on film characteristics and determine the optimized conditions for suitable application in thin-film solar cells. Morphological, structural, and opto-electronic properties of as-grown films were investigated and analyzed for different deposition powers. All the WS
2
films exhibited granular morphology and consisted of a rhombohedral phase with a strong preferential orientation toward the (101) crystal plane. Polycrystalline ultra-thin WS
2
films with bandgap of 2.2 eV, carrier concentration of 1.01 × 10
19
cm
−3
, and resistivity of 0.135 Ω-cm were successfully achieved at RF deposition power of 200 W. The optimized WS
2
thin film was successfully incorporated as a window layer for the first time in CdTe/WS
2
solar cell. Initial investigations revealed that the newly incorporated WS
2
window layer in CdTe solar cell demonstrated photovoltaic conversion efficiency of 1.2% with V
oc
of 379 mV, J
sc
of 11.5 mA/cm
2
, and FF of 27.1%. This study paves the way for WS
2
thin film as a potential window layer to be used in thin-film solar cells.
Journal Article
Current trends and prospects of tidal energy technology
Generation of energy across the world is today reliant majorly on fossil fuels. The burning of these fuels is growing in line with the increase in the demand for energy globally. Consequently, climate change, air contamination, and energy security issues are rising as well. An efficient alternative to this grave hazard is the speedy substitution of fossil fuel-based carbon energy sources with the shift to clean sources of renewable energy that cause zero emissions. This needs to happen in conjunction with the continuing increase in the overall consumption of energy worldwide. Many resources of renewable energy are available. These include thermal, solar photovoltaic, biomass and wind, tidal energy, hydropower, and geothermal. Notably, tidal energy exhibits great potential with regard to its dependability, superior energy density, certainty, and durability. The energy mined from the tides on the basis of steady and anticipated vertical movements of the water, causing tidal currents, could be converted into kinetic energy to produce electricity. Tidal barrages could channel mechanical energy, while tidewater river turbines can seize the energy from tidal currents. This study discusses the present trends, ecological effects, and the prospects for technology related to tidal energy.
Journal Article
Heading towards sustainable environment: exploring the dynamic linkage among selected macroeconomic variables and ecological footprint using a novel dynamic ARDL simulations approach
Ever since the emancipation of a country, its environmental quality has undergone a significant transition during the development phases; Bangladesh is no exception. Bangladesh is facing a serious threat in the age of global warming, and climate change as the country is looking forward in achieving the SDGs by 2030. Yet, there is a dearth of study regarding the relationship among crucial macroeconomic drivers and ecological footprint (a proxy for environmental degradation). Under the circumstances, this study explores the effects of economic growth, capital formation, urbanization, trade openness, energy use, and technological innovation on the ecological footprint by adopting the novel dynamic Autoregressive Distributed Lag (ARDL) simulations approach for Bangladesh, using annual frequency data from 1972 to 2017. Empirical results from the bounds test ascertained that there exists a long-run equilibrium association among the outlined variables. Furthermore, the novel dynamic ARDL simulation results revealed that Bangladesh is yet to achieve the environmental Kuznets curve (EKC) hypothesis. It was observed that the Bangladesh economy is still at the scale stage of its economic trajectory, emphasizing economic growth relative to her environmental status. However, capital formation, urbanization, and energy use seemed to degrade environmental quality, while trade openness and technological innovation upgraded the environmental quality. Putting it more elaborately, a unit escalation in GDP per capita increases the ecological footprint by 0.829% in the long run, while a unit increase in energy consumption upsurges the ecological footprint by 1.074% and 0.761% in the long run and short run, respectively. As regards technology innovation, one unit increase in it cutbacks the ecological footprint by 0.596% in the long run. Furthermore, the frequency domain causality unveiled the long-run feedback effect between economic growth and ecological footprint. The study further presents possible recommendations that can sustainably address environmental issues, keeping the economy buoyant.
Journal Article
In vitro antioxidant activity of Ficus carica L. latex from 18 different cultivars
As synthetic antioxidants that are widely used in foods are known to cause detrimental health effects, studies on natural additives as potential antioxidants are becoming increasingly important. In this work, the total phenolic content (TPC) and antioxidant activity of
Ficus carica
Linn latex from 18 cultivars were investigated. The TPC of latex was calculated using the Folin–Ciocalteu assay. 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and ferric ion reducing antioxidant power (FRAP) were used for antioxidant activity assessment. The bioactive compounds from
F. carica
latex were extracted via maceration and ultrasound-assisted extraction (UAE) with 75% ethanol as solvent. Under the same extraction conditions, the latex of cultivar ‘White Genoa’ showed the highest antioxidant activity of 65.91% ± 1.73% and 61.07% ± 1.65% in DPPH, 98.96% ± 1.06% and 83.04% ± 2.16% in ABTS, and 27.08 ± 0.34 and 24.94 ± 0.84 mg TE/g latex in FRAP assay via maceration and UAE, respectively. The TPC of ‘White Genoa’ was 315.26 ± 6.14 and 298.52 ± 9.20 µg GAE/mL via the two extraction methods, respectively. The overall results of this work showed that
F. carica
latex is a potential natural source of antioxidants. This finding is useful for further advancements in the fields of food supplements, food additives and drug synthesis in the future.
Journal Article
Production risk, technical efficiency, and input use nexus: Lessons from Bangladesh aquaculture
The optimal use of resources in aquaculture is important, especially in developing countries, to obtain the highest possible outcome from the production process to support food security and poverty alleviation. Thus, within this study, the risk, efficiency, and input‐use variation in aquaculture farms in Bangladesh is investigated using a flexible stochastic frontier model with a risk and an inefficiency function. The results reveal that feed, labor, and capital have positive and significant impacts on production. In addition, an increased fingerling density and a larger farm increase the risk, whereas the use of feed and the capital invested have the opposite effect. Access to extension services has a positive effect and increases farm efficiency. An investigation of the farm size–productivity inverse relationship reveals that this phenomenon is not applicable to Bangladesh aquaculture. In general, efficient farmers are large‐scale farmers, who use a lower stocking density but a higher feeding intensity, resulting in a higher yield. On average, farmers use less labor and feed than what is optimal. To increase efficiency and reduce risk, it is recommended that more technical knowledge on optimal input use, extension service, and capital is made available to aquaculture farmers.
Journal Article
New insights of phenolic compounds from optimized fruit extract of Ficus auriculata
In this study, the extraction conditions extracted maximize amounts of phenolic and bioactive compounds from the fruit extract of
Ficus auriculata
by using optimized response surface methodology. The antioxidant capacity was evaluated through the assay of radical scavenging ability on DPPH and ABTS as well as reducing power assays on total phenolic content (TPC). For the extraction purpose, the ultrasonic assisted extraction technique was employed. A second-order polynomial model satisfactorily fitted to the experimental findings concerning antioxidant activity (R
2
= 0.968,
P
< 0.0001) and total phenolic content (R
2
= 0.961,
P
< 0.0001), indicating a significant correlation between the experimental and expected value. The highest DPPH radical scavenging activity was achieved 85.20 ± 0.96% at the optimum extraction parameters of 52.5% ethanol (v/v), 40.0 °C temperature, and 22 min extraction time. Alternatively, the highest yield of total phenolic content was found 31.65 ± 0.94 mg GAE/g DF at the optimum extraction conditions. From the LC–ESI–MS profiling of the optimized extract, 18 bioactive compounds were tentatively identified, which may regulate the antioxidant activity of fruits of
F. auriculata
.
Journal Article
Characterization of freeze-dried, oven-dried and blanched house crickets (Acheta domesticus) and Jamaican field crickets (Gryllus assimilis) by means of their physicochemical properties and volatile compounds
Edible insects are repeatedly being considered as underutilized food candidate due to their high nutritional value. Although frequent acceptance of whole insects to consumer is still challenging, incorporation of insects in food as powder or paste has been suggested to increase their acceptability. Hence, Acheta domesticus and Gryllus assimilis were subjected to freeze drying, oven drying, and blanching to acquire a clear insight on the impact of the processing methods on the nutritional and physical properties of both species. Result showed that these three methods had limited effects on the proximate composition, fatty acid and amino acid profile but had significant impact on other parameters for both species. Vitamin B12 in A. domesticus did not change but G. assimilis changed due to the treatment. Freeze drying showed better lightness (L* value) and lower browning index for both cricket species. Oven drying and blanching resulted in lower lipid oxidation values than freeze drying for both cricket species; though lipid oxidation was in all cases well below the rejection limit. Esters were the predominant group of volatile compound in freeze and oven-dried cricket while least amount of volatiles were found in blanched cricket. The volatiles resulted from fatty acid oxidation were higher in freeze-dried crickets, while Maillard reaction products were found in oven-dried samples. Although freeze drying showed higher colour quality, oven drying exerted superior effect in terms of nutritional and flavour characteristics followed by blanching treatment.
Journal Article
Review of environmental challenges in the Bangladesh aquaculture industry
The increasing population and plateaued capture fishery landings have led to increasing demand for aquaculture products. However, environmental challenges are critical barriers to the sustainable development of aquaculture in developing countries. This review critically evaluates the environmental barriers facing aquaculture development in Bangladesh while laying out a roadmap for future development and spatial planning. An increase in the area used for aquaculture most often results in increasing pressure on natural resources such as land, water, energy, and the sources used for feed. Some of the negative externalities that this review focuses on are effluent discharge, the spread of diseases, and conflicts over land use with other ecosystem users. A way forward is to internalize these negative externalities and their costs into production decisions by farmers. Formulation of incentive-based pragmatic regulations can pave a forward path to increased environmental sustainability.
Journal Article
Economic performance differentials of coastal and noncoastal pond aquaculture farms in Bangladesh
Due to the advantageous tidal movements and water exchange in coastal ponds, pangasius and tilapia farmers in Bangladesh benefit from higher water quality and nutrient levels, leading to higher quality fish at lower feed and water exchange costs. Therefore, the economic performance of coastal farms may be higher than for noncoastal farms. This study investigates the differences in technical efficiency and other economic performance indicators between coastal and noncoastal pond aquaculture farms. Data from 121 coastal and 479 noncoastal farms were analyzed using meta-frontier data envelopment analysis (DEA) and propensity score matching (PSM). Results show coastal farms are more efficient than noncoastal ones due to their advantageous locations. Locating new aquaculture farms to coastal regions could increase average output with the same inputs, follow industry best practices, save costs, and achieve higher returns on investment, reaching break-even at lower prices and quantities than noncoastal farms. Prioritize the development of aquaculture in coastal regions by providing incentives and infrastructure supports, as these areas offer competitive advantage over noncoastal regions.
Journal Article