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One effective way to prevent toxicity and improve the stability of materials for photovoltaic applications is to exclude lead and organic molecules from perovskite materials. Specifically, the CsSn1−xGexI3 appears to be a promising contender; nonetheless, it requires optimization, particularly bandgap tuning by doping concentration modifications. In this study, density functional theory (DFT) was employed to comprehensively analyze the electronic properties of CsSn1−xGexI3 that influenced light-matter interactions tuning of the perovskite materials by varying composition in B site atoms. We use the solar cell capacitance (SCAPS-1D) simulator to compute device performance; however, it computes the absorption spectrum using a simplified mathematical function that approximates the actual spectrum. To achieve a quantum-mechanical level of accuracy DFT extracted parameters like absorption spectra and bandgap were fed into SCAPS-1D. We find that increasing the Ge concentration leads to a higher bandgap and improved absorption profile, thereby enhancing solar energy conversion efficiency. Thermal and field distribution analyses were also done for the optimized device through a finite-difference time-domain (FDTD) framework. By optimizing the absorber layer with a 75% Ge concentration, we achieve a remarkable PCE of 23.55%. Our findings guide future research in designing high-performance non-leaded halide PSCs, paving the way for low-cost, stable, and highly efficient solar cells through atomic doping-tuned perovskite absorber layers. [ABSTRACT FROM AUTHOR]

Ab-initio simulations using density functional theory (DFT) were employed to investigate the structural, mechanical, electronic, magnetic, optical, and thermoelectric properties of halide perovskites (X = Cl, Br, I). Structural optimization and mechanical stability assessments confirm the reliability of these perovskites in a hexagonal P mc symmetry. The stability of the ferromagnetic phase was validated through total crystal energy minimization via Murnaghan's equation of state. Electronic band structures and density of states, derived from the generalized gradient approximation (GGA), reveal a semiconducting ferromagnetic nature in the spin up channel, spotlighting their potential in semiconductor spintronic applications. Phonon dispersion analysis of and revealed positive phonon modes throughout the entire Brillouin zone, confirming their dynamical stability. In contrast, demonstrated dynamical instability. The elastic constants confirm the mechanical stability and ductile nature of the perovskites. Optical and dielectric properties of these perovskites show significant UV absorption and photoconductivity, making them highly suitable for optoelectronic and solar cell applications. Finally, transport properties, such as the Seebeck coefficient, electrical conductivity, thermal conductivity, power factor, and figure of merit (ZT) unveil their exceptional thermoelectric performance. Combining half-metallic ferromagnetic traits with superior thermoelectric and optoelectronic performance positions compounds as exceptional candidates for applications in spintronics, optoelectronics, and thermoelectrics. This comprehensive investigation demonstrates their ability to excel across a diverse array of advanced technological applications. [ABSTRACT FROM AUTHOR]

The shifting of tannery industries from Hazaribagh to Savar adjacent to Dhaleshwari River might have inevitable adverse impacts, especially the heavy metal contamination of both terrestrial and aquatic ecosystems. The study was carried out to investigate the concentrations of four heavy metals in the soil, water, and plant samples collected from around Dhaleshwari River adjacent to the Bangladesh Small & Cottage Industries Corporation Tannery Industrial Estate, Dhaka. This study revealed that average concentrations of cadmium and chromium in soil exceeded the maximum permissible limit of World Health Organization (1996) and average concentrations of lead, cadmium, and chromium in water exceeded the maximum permissible limit of World Health Organization (2011) and Environmental Conservation Rules (1997). The average concentrations of lead, cadmium, and chromium in the roots and shoots of both Eichhornia crassipes and Cynodon dactylon exceeded the maximum permissible limit of Food and Agriculture Organization/ World Health Organization (2016). Ecological risk assessment using indices model for soil pollution indicated that soil is mostly contaminated with cadmium and chromium which can pose strong ecological risk Health risk assessment using indices model for water pollution revealed the high degree of contamination and unacceptable non-carcinogenic risk and carcinogenic risk for adults as well as children through ingestion of water. Average bioconcentration factor and bioaccumulation factor were higher in Eichhornia crassipes than Cynodon dactylon for lead, cadmium, and chromium. Average translocation factor was also higher in Eichhornia crassipes for all the metals except cadmium. It is suggested remedial and mitigation measures be instituted to control environmental degradation of the newly established Tannery Industrial Estate. [ABSTRACT FROM AUTHOR]

Urban sprawl is a global phenomenon that has resulted in a substantial impact on ecosystem services. This study assessed how land use changes have affected the ecosystem services in Dhaka and Gazipur districts, two important economic centers of Bangladesh. This study analyzed changes in land use categories and their effects on ecosystem services during a thirty-year period, from 1990 to 2020, using LandSat data and published coefficient values. Additionally, a sensitivity analysis was undertaken to evaluate the ramifications of altering these coefficients on the resultant estimated values. The study revealed that in both Dhaka and Gazipur districts, the expansion of settlement areas and the reduction in tree vegetation cover have led to a significant decline in the overall value of ecosystem services. Over a 30-year timeframe, Gazipur experienced a more substantial loss in tree vegetation cover compared to Dhaka, whereas Dhaka witnessed a greater increase in settlement areas than Gazipur. Remarkably, during the most recent decade (2010–2020), the Gazipur district encountered heightened urban expansion and a more significant reduction in tree vegetation compared to Dhaka. The loss of the entire ecosystem service value was significant, amounting to USD 206.24 million for Dhaka and USD 381.27 million for Gazipur. This loss was primarily attributed to the decline in agricultural land, water bodies, rivers, and a reduction in tree vegetation. The study recommends that a more responsible land-use plan be created to protect tree vegetation, sustainable agriculture, and water bodies, which have the highest ecosystem service value in the study area. Overall, this study highlights the need for sustainable land-use techniques and offers insightful information about how urbanization affects ecosystem services in the investigated areas. [ABSTRACT FROM AUTHOR]

Bangladesh is one of the most polluted nations in the world, with an average Air Quality Index (AQI) of 161 in 2021; its capital, Dhaka, has the worst air quality of any major city in the world. The present study aims to analyze the spatiotemporal distribution of air quality indicators in the greater Dhaka region, forecast weekly AQI, and assess the performance of a novel particulate matter filtration unit in removing particulate matter. Air quality indicators remained highest during the dry season with an average of 128.5 μm/m3, while the lowest concentration was found in the monsoon season with an average of 19.096 μm/m3. Analysis revealed a statistically significant annual increasing trend of CO, which was associated with the growing number of brick kilns and usage of high-sulfur diesel. Except for the pre-monsoon AQI, concentrations of both seasonal and yearly AQI and PM2.5 showed decreasing trend, though predominantly insignificant, demonstrating the improvement in air quality. Prevailing winds influenced the seasonal distribution of tropospheric CO & NO2. The study also employed a seasonal autoregressive integrated moving average (ARIMA) model to forecast weekly AQI values. ARIMA (3,0,4) (3,1,3) at the 7-periodicity level performed best forecasting the AQI values among all developed models with low root mean square error (RMSE)-29.42 and mean absolute percentage error (MAPE)-13.11 values. The predicted AQI values suggested that the air quality would remain unhealthy for most weeks. The experimental simulation of the particulate matter filtration unit, designed in the shape of a road divider, generated substantial cyclonic motion while maintaining a very minimal pressure drop. In the real-world scenario, using only cyclonic separation and dry deposition, the suggested air filtration system removed 40%, 44%, and 42% of PM2.5, PM10, and TSP, respectively. Without employing filters, the device removed significant amounts of particulate matter, implying enormous potential to be used in the study area. The study could be useful for policy makers to improve urban air quality and public health in Bangladesh and in other developing countries. [ABSTRACT FROM AUTHOR]

Background: Antimicrobials like fourth-generation cephalosporins, carbapenems, or β-lactams are widely used in treatment of febrile neutropenia (FN). The present study aimed to compare the efficacy of cefepime, meropenem, and piperacillin/tazobactam as initial treatment for chemo-induced FN in patients with hematological malignancy. Methods: This was an observational study conducted in the Department of Hematology of Dhaka Medical College Hospital from July 2020 to June 2021 including 99 adult FN patients with hematological malignancy who were randomized equally to three treatment arms to receive cefepime, meropenem, or piperacillin/tazobactam as an empirical antibiotic. Response to therapy was defined as improvement in symptoms (e.g., defervescence) or in laboratory values including neutrophil counts on day 3 and day 7 after the initiation of the therapy. Chi-square test and Fisher's exact test were used to compare the efficacy of the treatment regimens. Results: Response rate to initial treatment with different antibiotic regimens was similar without any statistically significant difference (60.6%, 63.6%, and 51.5% on day 3 and 63.6%, 75.8%, and 66.7% on day 7 for cefepime, meropenem, and piperacillin/tazobactam, respectively, p-value > 0.05) irrespective of underlying diagnosis, the severity of neutropenia, and cause of fever. Conclusion: Initial therapy with cefepime, meropenem, or piperacillin/tazobactam is safe and equally effective in chemo-induced FN in patients with hematological malignancy. This finding may be considered in clinical practice for optimum therapeutic outcomes. [ABSTRACT FROM AUTHOR]

Considering the growing threats of climate change, in addition to mitigation strategies, it is highly and equally critical to understand the socio-economic determinants of climate adaptation in order to develop climate adaptation policies. This study makes a first attempt to explore the determinants of adaptation to climate change and choices of adaptation strategies at a larger spatial scale of the south-west coastal areas in Bangladesh, which is one of the most climate-vulnerable regions in the world. We employ both qualitative and quantitative approaches in order to examine farmers' perception of climate risks, determinants and choices of adaptation strategies to climate change in six coastal districts of Bangladesh. Farmers are adapting to these situations using their knowledge and experience. The study reveals that a number of adaptation strategies have been taken to reduce the negative impacts of climate change. These adaptation strategies are categorized into four groups: crop management, water management, land management, and income diversification. Availability of inputs, high production cost, agricultural extension service, and proper adaptation knowledge and experiences were noted as the main non-climatic challenges, as well as different climatic factors in agricultural adaptation strategies. Statistical analysis indicates that the different socio-economic determinants of farmers significantly influence their choices of adaptation to climate change. Farmers adopt these adaptations mostly autonomously rather than on the advice of government. This study could be useful for developing national adaptation policies in Bangladesh and other similar developing countries. [ABSTRACT FROM AUTHOR]

The physical and dynamical characteristics of pre-monsoon (March–May) thunderstorms (TS) are investigated over Bangladesh using the Weather Research and Forecasting (WRF) model. The model was run for 24-h using 6-hourly data sets as initial and lateral boundary conditions. The Milbrandt cloud microphysics scheme, Krain–Fritsch cumulus scheme, and Yonsei University planetary boundary layer are found to be the best combination by comparing the root mean square error of rainfall from 18 sensitivity experiments. The synoptic condition and atmospheric instability associated with three TS cases have been analyzed based on mean sea level pressure, convective available potential energy (CAPE), and thermodynamic indices. CAPE is found between 500 and 2700 J kg−1 at 0000 UTC for the TS cases. The presence of low-level southerly wind from the Bay of Bengal and upper-level westerly or north-westerly wind with speeds ranging from 5 to 30 m s−1 is found during the storms. The cloud characteristics and intensity were investigated based on Doppler Weather Radar and INSAT 3DR satellite observations. Cloud micro-physical hydrometeors and other composite features (e.g., cloud top and core precipitation altitude, length of squall line) were also studied by the model and then compared with available observed values. For 24-h rainfall, 2 × 2 contingency tables are computed using Model Evaluation Tools. Categorical skill scores such as proportion correct, frequency bias index, probability of false detection, false alarm ratio, and Gilbert skill score were calculated to evaluate the model's performance. The forecast goodness is found to be reasonably satisfactory after analyzing the significance of the skill scores. [ABSTRACT FROM AUTHOR]