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The study proposes the use of microbial fuel cell (MFC) technology to reduce toxic Cr(VI) present in industrial wastewater to less toxic trivalent chromium [Cr(III)], while generating electricity through a bioelectrochemical oxidation-reduction process. Factors influencing the treatment process and electricity generation include the concentration of Cr(VI) in wastewater, substrate types used for anodes, types of microorganisms involved, types of cathode and anode, surface area of the cathode and anode, and pH and temperature of cathodic and anodic solutions. While other heavy metals in wastewater may be removed by MFC technology, Cr(VI) removal is more efficient in terms of electricity generation. Previous research indicated that the maximum electrical power generated by Cr(VI) removal through the use of MFCs is 1600 mW/m2, which is expected to increase as the factors affecting this process are optimized. Based on current data, MFC-based electricity generation along with Cr(VI) removal is a potential future source of sustainable energy. However, research priorities need to focus on reducing the cost of MFC technology by using economical and effective materials and increasing electricity production.

The COVID-19 pandemic led to the explosion of biomedical waste, a global challenge to public health and the environment. Biomedical waste comprising plastic can convert into microplastics (MPs,5 mm) by sunlight, wave, oxidative and thermal processes, and biodegradation. MPs with additives and contaminants such as metals are also hazardous to many aquatic and terrestrial organisms, including humans. Bioaccumulation of MPs in organisms often transfers across the trophic level in the global food web. Thus, this article aims to provide a literature review on the source, quantity, and fate of biomedical waste, along with the recent surge of MPs and their adverse impact on aquatic and terrestrial organisms. MPs intake (ingestion, inhalation, and dermal contact) in humans causing various chronic diseases involving multiple organs in digestive, respiratory, and reproductive systems are surveyed, which have been reviewed barely. There is an urgent need to control and manage biomedical waste to shrink MPs pollution for reducing environmental and human health risks.

Polygenic risk scores (PRS) are increasingly used to predict diseases (e.g., schizophrenia). However, the proper application of the PRS in psychological studies is sparse. We aimed to evaluate the methodological aspects of using PRS as a covariate in causal association studies in psychology. We conducted a simulation study using realistic scenarios, such as gene and exposure or confounder interaction, gene and gene interaction, gene acts as confounding and instrumental variable and replicated each scenario 1000 times. We found that when the genotype(s) that was used for calculating PRS interacted with the exposure and if the analyses considering this interaction, the exposure effect similar with the true value. However, a significant amount of bias was present even after adjustment for the measured confounders i) when the gene interacted with the unmeasured confounder and this bias amplified when the interaction effect was two times stronger; and ii) when the gene acts as a confounder or instrumental variable. Therefore, theoretical knowledge of psychology should be incorporated when the PRS is utilized in psychological causal association studies in order to reduce systematic bias and improve the precision of the exposure effect.

Tick and tick-borne diseases cause significant impediments to livestock health and production; however, information on the tick fauna is significantly limited in Bangladesh. This study was aimed to investigate tick fauna in Sylhet sub-district of Bangladesh targeting animal hosts and environment. A total 1427 ticks were collected by using blunt forceps, hand picking and dragging techniques from host body and environment during October 2018 to March 2019. Identification was made using morpho-taxonomical keys. Eight species from three separate genera of tick, namely Rhipicephalus(≈Boophilus) microplus, Rhipicephalus decoloratus, R. annulatus, R. sanguineus, Haemaphysalis intermedia, H. bispinosa, H. leachi, and Amblyomma variegatum were identified. Rhipicephalus spp. was dominant in the hosts whereas, Haemaphysalis spp. was the most prevalent in the environment. This study for the first-time enlisted ticks in two different ecological settings in Sylhet, Bangladesh. Further investigations should be made to evaluate the burden and control the associated socio-economic risk.

We aimed to examine the impact of weather on COVID-19 confirmed cases in South Asian countries, namely, Afghanistan, Bangladesh, India, Pakistan, and Sri Lanka. Data on daily confirmed cases, together with weather parameters, were collected from the first day of COVID confirmed cases in each country to 31 August 2020. The weather parameters were Rainfall (mm), relative humidity (%), maximum and minimum temperature (°C), surface pressure (kPa), maximum air pollutants matter PM 2.5 (μg/m3) and maximum wind speed (m/s). Data were analyzed for each investigated countries separately by using the Autoregressive Integrated Moving Average with Explanatory Variables (ARIMAX) model. We found that maximum wind speed had significant negative impact on COVID-19 transmission in India (−209.45, 95% confidence interval (CI): −369.13, −49.77) and Sri Lanka (−2.77, 95% CI: −4.77, −0.77). Apart from India, temperature had mixed effects (i.e., positive or negative) in four countries in South Asia. For example, maximum temperature had negative impact (−30.52, 95% CI: −60.24, −0.78) in Bangladesh and positive impact (5.10, 95% CI: 0.06, 10.14) in Afghanistan. Whereas rainfall had negative effects (−48.64, 95% CI: −80.17, −17.09) in India and mixed effects in Pakistan. Besides, maximum air pollutants matter PM 2.5 was negatively associated with the confirmed cases of COVID-19. In conclusion, maximum wind speed, rainfall, air pollutants (maximum PM 2.5) and temperature are four variables that could play a vital role in the transmission of COVID-19. Although there is a mixed conclusion regarding weather parameters and COVID-19 transmission, we recommend developing environmental policies regarding the transmission of COVID-19 in South Asian countries., Graphical abstract Unlabelled Image, Highlights • A new study examined the impact of weather on COVID-19 transmission for the first time in five south Asian countries. • Autoregressive Integrated Moving Average with Explanatory Variables (ARIMAX) model was used to assess the impact. • Lower wind speed could modulate the transmission of COVID-19. • Excess rainfall could reduce the transmission whereas the temperature impact was not consistent throughout the countries. • Low concentrations of air pollutants can increase the risk of infection, but it also depends on rainfall.

Silicon (Si) anodes suffer from huge volume changes leading to cracking and pulverization impacting the battery life. To deliver high energy and long-term stability, we present a unique and facile prelithiated silicon nano alloy (SiNA) material with lithium stearate as reagent. Structurally controlled SiNA (in this work Si -iron (Fe)-manganese (Mn) combination) design with active Si surrounded by inactive buffer matrix to reduce mechanical deterioration during expansions was synthesized using a low-cost and low-temperature process relying on mechanical milling. Prelithiation was accomplished to compensate for the initial irreversible loss by pre-feeding with the lithium reagent to form a protective artificial solid electrolyte interphase (SEI) and prefill the mechanical crack voids of the SiNA to improve the mechanical properties necessary for long-term cyclability. The approach was to mechanically mix SiNA with lithium stearate followed by heat treatment above the melting point of lithium stearate to allow its easy diffusion with the surface and mechanical voids of the SiNA. Prelithiated SiNA exhibited enhanced physicochemical properties and featured boosted mechanical integrity characterized by nanoindentation. In overall, prelithiated SiNA revealed excellent electrochemical properties and long-term cycling stability addressed at significantly high loading (∼2 mg cm−2) and over 250 cycles, demonstrating its transformable potential to high energy applications.

Tropical forests play a significant role in sequestrating and storing atmospheric carbon di-oxide (CO2) emissions. However, estimation of forest carbon (C) stocks in relation to changes in forest structure and disturbances are less studied. We estimated forest C stocks in live trees, saplings, lianas, deadwood, forest floor, and soil in Sitapahar natural forest reserve of Bangladesh based on field measurements and laboratory assessments. We categorized the 99 temporary sample plots into three canopy densities: closed, moderately closed, and open. According to the results, the forest C stocks were dominated by the soil C pool and forest C stocks in the closed canopy (91 Mg ha−1) differed significantly from that in the open canopy (50 Mg ha−1). Forest C stocks were also affected by basal area (BA) and deadwood C stocks. In the open canopy, the second highest contributor to forest C stock was deadwood, whereas it was above and below-ground live biomass in the closed and moderately closed canopies. In the open canopy, forest disturbances significantly decreased height and BA, and C stocks in live biomass were significantly lower compared to the other two canopy densities. In the open canopy, decreased tree density resulted in the lowest C stock in litterfall and humus, and they were up to 95% lower compared to the other two canopy densities. C stocks in humus were higher than those in litterfall in the closed and moderately closed canopies, which was opposite to that in the open canopy. The soil C stock decreased with soil depth and the highest C stocks across all depths were in the closed canopy, followed by the moderately closed and open canopy. This study also provided a stand-level estimation of C stocks that contribute to determining which tree species sequester more carbon, such as Swintonia floribunda, Lannea coromandelica, Anacardiaceae and Moraceae.

The internet has become an essential part of our daily life. But excessive usage can have a negative impact on the physical health of its users. Over the last decade, the use of Social Media (Facebook) has been increasing rapidly and the younger generations getting addicted to it. But all possible health impacts of excessive use of internet are yet to be thoroughly evaluated, especially in such a developing country as Bangladesh. The present study aims to understand possible health deteriorations from excessive use of Facebook in a cohort of university students of Bangladesh. A cross-sectional study was conducted on 1186 students from two public universities and 1472 from several private universities of Bangladesh using a comprehensive questionnaire. The data were analyzed using the chi-square test to understand the association between Facebook usage behaviors and physical health status. We found that ~70% of the students used the internet for at least 4–6 hours/day, and ~27% of them used Facebook for >3 hrs. Students frequently use social media (mostly Facebook) for news and social communication. About 50% of the students reported wasting time on Facebook and going to sleep late because of it. Importantly, 47.3% students reported that excessive use of Facebook results sleeping disturbance and has a negative impact on the concentration of daily works/studies (p < 0.001). In addition, they experienced several other health problems, including worsening eyesight (71.2%), headaches (15.4%), back and neck pain (28%). Although not statistically important, a fair number of students sought medical attention due to the daily excessive use of internet (p-value = 0.112). These findings demands better understanding of the all possible impacts of using excessive internet among the University students, which can help take the necessary initiatives to encourage good use of the internet. Further extension of this study is suggested at all education levels to reveal the full scenario of degree of excessive internet use and its impact on the healths of Bangladeshi students., Highlights • ~70% University students of Bangladesh use internet for at least 4–6 hrs/day, among them ~27% use Facebook for >3 hrs. • Around half of the students felt using Facebook wasted time and reported sleeping disturbances. • Excessive use of internet caused problems such as weakening vision, occasional and frequent headaches, and back and neck pain., Facebook, Student, Time, Health, Bangladesh.

A lignin/polyvinyl alcohol (lignin/PVA) nanofiber membrane has been prepared as a separator for lithium-ion batteries (LIBs) using a simple, low-cost, environment-friendly, water-based method. Lignin is a widely abundant, naturally occurring biopolymer and polyvinyl alcohol (PVA) is a biocompatible polymer with good chemical and thermal stability. In this work, lignin and PVA were dissolved in water, and fibers were drawn from the solution to form a non-woven membrane. A highly porous interpenetrating network structure resulted that showed high electrolyte uptake, excellent compatibility, and superior wettability. The membrane also showed high thermal stability and flame retardant properties. Electrochemical performance revealed high rate capability with the lignin/PVA membrane that is attributed to its high ionic transport property. The as prepared lignin/PVA membrane, thus, can be considered as a separator for safer and faster LIBs with various different anodes.

Nanotechnology is an emerging technology to develop efficient and enhanced batteries including the most popular lithium-ion batteries. The importance of cathode materials in LIBs are tremendous since the LIBs are still cathode limited in design. In this review, we have summarized various approaches for the synthesis of nanostructured cathode materials with enhanced properties to improve electrochemical performances of LIBs. We concluded the review with a comparison of the different techniques discussed and addressed the importance of nanotechnology in the race to build improved batteries.

River water is very much important for domestic, agriculture and industrial use in Bangladesh which is in critical condition from long time based on research data. During last 40 years, extreme pollution events occurred in peripheral rivers surrounding Dhaka city and Karnaphuli River in Chittagong city. Present data showed that other urban rivers are also in critical condition especially Korotoa, Teesta, Rupsha, Pashur and Padma. The pollutants flowing with water made a severe pollution in downstream areas of rivers. Metals concentrations in river water was found to be higher in dry season. Dissolve oxygen (DO) was nearly zero in Buriganga River and several points in Turag, Balu, Sitalakhya and Karnaphuli River. NO3-, NO2- and PO43- pollution occurred in different rivers. Zn, Cu, Fe, Pb, Cd, Ni, Mn, As and Cr concentration was above drinking water standard in most of the river and some metals was even above irrigation standard in water from several rivers. Sediment data showed very much higher metal concentrations in most of the rivers especially peripheral rivers in Dhaka and Karnaphuli, Korotoa, Teesta, Rupsha and Meghna River. Metal concentrations in sediment was above US EPA threshold value in most of the rivers. Metal concentrations in fish and agricultural crops showed that bioaccumulations of metals had occurred. The concentration of metals showed the trend like: water, Industrialization, Economic Development, Rivers, Pollution, Heavy Metals, Effects.

The ab initio calculations of polypyridine π*-orbital energies are the basis for assignment of the lowest energy, highest intensity metal-to-ligand charge transfer (MLCT) transitions in simple ammine–polypyridine–ruthenium(II) complexes. A gaussian analysis of the absorption and emission spectra of these complexes enables the evaluation of reorganizational energies for the vertical MLCT transitions from component bandwidths and from apparent vibronic progressions. The observed bandwidths are about half of the widths expected in the limit of no metal–ligand mixing. The excited state-ground state mixing coefficient, α DA , is inferred to be about 0.3 in [Ru(NH 3 ) 4 bpy] 2+ based on this observation and a perturbation theory argument. These estimated reorganizational energies are combined with the observed ambient Stokes shifts to determine that the excited state electron exchange energy, K e , is small (600–1200 cm −1 for 2,2′ bipyridine complexes; ∼1500 cm −1 for 2,3-bis-(2-pyridyl)pyrazine complexes), but significant. This and the observation that the NH stretching frequency increases as the vertical MLCT energy (or α DA 2 ) decreases suggests that there is significant charge delocalization in these complexes.

The very sensitive fluorimetric determination of selenium(IV) is based on its oxidation of the non-fluorescent 2-(α-pyridyl)thioquinaldinamide in slightly acidic solution (0.05–0.15 M sulphuric acid). The excitation and emission wavelengths are 350 nm and 500 nm, respectively. Linear calibration graphs are obtained for different ranges of selenium concentration between 0.01 ng ml−1 and 0.5 μg ml−1. Over sixty ions either do not interfere or can be masked in the determination of 1 ng ml−1 Se(IV). The method is applied successfully to various synthetic mixtures and to a native sulphur sample. The reaction is fast and the fluorescent system is stable for 24 hours.