REMOVAL OF ARSENIC AND CHROMIUM FROM WATER USING MAGNETITE NANOPARTICLES

Groundwater contamination by heavy metals is a major environmental concern in areas where the water supply system draws primarily on groundwater. Several methods of arsenic and chromium ions removal from water are already available. Among all removal methods, adsorption by magnetite nanomaterials is the most promising. In the present study, nano-size magnetite particles were used in the removal of arsenic and chromium species from different water samples, namely, stock solutions of arsenic and chromium, synthetic water, natural groundwater and spiked groundwater obtained from Srinagar, Munshiganj and Sylhet Golapganj in Bangladesh. The intent was to identify or develop a practical method for future groundwater remediation at the site. The results of the study showed 95-99% arsenic and chromium ions removal under controlled pH conditions and magnetite nanoparticles can adsorb arsenic and chromium(VI) more readily in an acidic pH range. Redox potential and pH data identified possible dominating species and oxidation states of arsenic and chromium in solution. The results also showed the limitation of arsenic and chromium removal by nanosized magnetite in the presence of a competing anion such as phosphate. At a fixed adsorbent concentration, arsenic and chromium ions removal decreased with increasing phosphate concentration. Nano-size magnetite particles removed less than 50% arsenic from synthetic water containing more than 3 mg/L phosphate and less than 50% chromium(VI) ion from synthetic water containing more than 5 mg/L phosphate. In natural groundwater containing more than 6 mg/L phosphate, less than 60% arsenic ion removal was achieved. In this case, it is iii anticipated that an optimum design with magnetite nanoparticles may achieve high arsenic ion removal in the field

Application of Mixed Iron Oxides in Subsurface Remediation Technologies

Heavy metal contamination of soil and groundwater has been a concern in water supply and public health in many countries where the water supply system draws primarily from groundwater. In the present study, mixed maghemite-magnetite nanoparticles have been used as adsorbents for Cr(VI), As and Cd(II) removal. From the study, it is apparent that the removal of Cr(VI ), Cd(II) and As(V) by mixed iron oxide nanoparticles depends on pH, temperature, contact time, solid/liquid ratio and initial concentration of heavy metals. The results showed that Cr(VI) adsorption on mixed maghemite-magnetite was dependent on solution pH between 3 and 6. Theoretical multiplet analyses in X-ray photoelectron spectroscopy (XPS) study showed that during Cr adsorption, the amount of maghemite increased from 70 to 89%. Fe(II) was transformed into Fe(III) by the redox reaction and Cr(VI) species were reduced to Cr(III) species. In arsenic removal study, it was found that the percent of maghemite also increased for As(V) and As(III) adsorption. At the same time, the percentage of magnetite was reduced for both cases. Thus, a redox reaction occurred on the mixed magnetite-magheamite surface when arsenic was introduced. In cadmium removal study, adsorption capacity of mixed maghemite-magnetite for Cd(II) ions increased with an increase in the pH of the adsorbate solution. The results showed that 0.8 g/L of 20-60 nm maghemite-magnetite particles removed up to 1.5 mg/L Cd. The XPS surveys confirmed that As, Cr(VI) and Cd(II) ions may undergo oxidation-reduction reactions upon exposure to mixed maghemite-magnetite, or may be fixed by complexation to the oxygen atoms in the oxyhydroxy groups.The investigation of transport and chemical states analysis during arsenic removal by monolith slag from nickel smelting revealed that slag was efficient in arsenic removal, attaining equilibrium sorption capacities in the range of 1000-1054 µg/g for an initial arsenic concentration of C0= 10 mg/L. Column studies showed the sorption of arsenic by smelter slag (a waste material) was complex and involved both chemisorption and physical sorption. Sorption capacities for As(V) were significantly higher for Ni smelter slag. Raman spectroscopy and XPS results demonstrate that the As reacted with a large proportion of the slag in the experiment. Thus, further investigation would be necessary to evaluate the applicability of mixed iron oxide loaded particles for subsurface remediation at field scale

Socioeconomic inequality in child injury in Bangladesh – implication for developing countries

<p>Abstract</p> <p>Background</p> <p>Child injury is an emerging public health issue in both developed and developing countries. It is the main cause of deaths and disabilities of children after infancy. The aim of this study was to investigate the socioeconomic inequality in injury related morbidity and mortality among 1–4 years children.</p> <p>Materials and methods</p> <p>Data used for this study derived from Bangladesh Health and Injury Survey. A multistage cluster sampling technique was conducted for this survey. In this study quintiles of socioeconomic status were calculated on the basis of assets and wealth score by using principle component analysis. The numerical measures of inequality in mortality and morbidity were assessed by the concentration index.</p> <p>Results</p> <p>The poorest-richest quintile ratio of mortality due to injury was 6.0 whereas this ratio was 5.6 and 5.5 for the infectious diseases and non-communicable diseases. The values of mortality concentration indices for child mortality due to infection, non-communicable diseases and injury causes were -0.40, -0.32 and -0.26 respectively. Among the morbidity concentration indices, injury showed significantly greater inequality. All the concentration indices revealed that there were significant inequalities among the groups. The logistic regression analysis indicated that poor children were 2.8 times more likelihood to suffer from injury mortality than rich children, taking into account all the other factors.</p> <p>Conclusion</p> <p>Despite concentration indices used in this study, the analysis reflected the family's socioeconomic position in a Bangladesh context, showing a very strong statistical association with child mortality. Due to the existing socioeconomic situation in Bangladesh, the poor children were more vulnerable to injury occurrence.</p

Waste management practices and profitability analysis of poultry farming in Mymensingh district: A socioeconomic study

Poultry manure is a hazard to the environment and health due to the release of toxic substances as well as pathogenic microorganisms. The present study was undertaken to assess the current scenario of poultry waste management considering its social as well as environmental and health hazards. A questionnaire based survey was conducted in 36 commercial poultry farms (which included 15 broiler, 14 layer, 3 cockerel and 4 mixed farms) in Mymensingh district from February to June 2016. Most of the broiler and layer farms had between 500 to 2000 birds, while most of the cockerel farms had between 3000 to 4000 birds. The study showed that 69 percent of the poultry farmers were unaware of the health and environmental problems of the poultry waste. Majority of the small scale farmers disposed their droppings to fish ponds (31 percent) and agricultural farms (16 percent) directly, while only 6 percent farmers used those droppings in biogas plant. However, 53 percent farmers had knowledge about hygienic handling of poultry dropping, although only 19 percent of them used protective gloves during dropping handling. The profitability analysis revealed that average variable cost and fixed cost per farm per year were TK. 2,17,355 and TK. 3,93,106, respectively. The benefit cost ratio per farm per year poultry farming was 1.55. Considering the findings, it is suggested that proper poultry waste management could be highly beneficial for the farmers. On the other hand, improper dispose of poultry litter could be a cause for social, environmental and public health hazard

Harnessing Large Language Models Over Transformer Models for Detecting Bengali Depressive Social Media Text: A Comprehensive Study

In an era where the silent struggle of underdiagnosed depression pervades globally, our research delves into the crucial link between mental health and social media. This work focuses on early detection of depression, particularly in extroverted social media users, using LLMs such as GPT 3.5, GPT 4 and our proposed GPT 3.5 fine-tuned model DepGPT, as well as advanced Deep learning models(LSTM, Bi-LSTM, GRU, BiGRU) and Transformer models(BERT, BanglaBERT, SahajBERT, BanglaBERT-Base). The study categorized Reddit and X datasets into "Depressive" and "Non-Depressive" segments, translated into Bengali by native speakers with expertise in mental health, resulting in the creation of the Bengali Social Media Depressive Dataset (BSMDD). Our work provides full architecture details for each model and a methodical way to assess their performance in Bengali depressive text categorization using zero-shot and few-shot learning techniques. Our work demonstrates the superiority of SahajBERT and Bi-LSTM with FastText embeddings in their respective domains also tackles explainability issues with transformer models and emphasizes the effectiveness of LLMs, especially DepGPT, demonstrating flexibility and competence in a range of learning contexts. According to the experiment results, the proposed model, DepGPT, outperformed not only Alpaca Lora 7B in zero-shot and few-shot scenarios but also every other model, achieving a near-perfect accuracy of 0.9796 and an F1-score of 0.9804, high recall, and exceptional precision. Although competitive, GPT-3.5 Turbo and Alpaca Lora 7B show relatively poorer effectiveness in zero-shot and few-shot situations. The work emphasizes the effectiveness and flexibility of LLMs in a variety of linguistic circumstances, providing insightful information about the complex field of depression detection models

Climate and salinity together control above ground carbon accumulation in the Sundarbans mangrove ecosystem

Mangroves play a crucial role in mitigating climate change through carbon (C) accumulation. Developing robust methods for the estimation of long-term C accumulation is essential for monitoring and reporting carbon financing projects under different global mechanisms. Moreover, understanding the effects of climate and habitat on C accumulation is important for developing mangrove management plans and conservation options. In this study, long-term above ground C accumulation in the three most dominated mangrove tree species, Heritiera fomes, Excoecaria agallocha and Sonneratia apetala, was estimated using a dendrochronological approach in two contrasting (low vs high) salinity zones in the Bangladesh Sundarbans. In addition, how climate and habitat (e.g., regulators and soil resources) influence C accumulation was analyzed. For the first time, we estimated C accumulation in mangrove species over their entire lifetime using stem disc-derived tree-ring data. The C accumulation patterns exhibited similar patterns of variation, increasing from pith to bark in each case. C accumulation was significantly higher in the low salinity zone (LSZ) than in the high salinity zone (HSZ) (p < 0.05). The cumulative C accumulation increased with tree age in each case, and C accumulation was influenced mainly by seasonal precipitation, especially during monsoon. General additive modeling (GAM) revealed that soil salinity had a stronger effect on C accumulation variability in the studied tree species. Other regulatory variables (i.e., siltation and elevation) and soil resources (i.e., P and K) had species-specific influences on C accumulation. Tree-ring data show the potential to yield better biomass and C estimations, which could aid frequent and rapid reporting of C accumulation in mangroves. Moreover, the results also suggest that climate and regulatory variables, especially soil salinity, together impact the C cycles in the Sundarbans

Salinity drives growth dynamics of the mangrove tree Sonneratia apetala Buch. -Ham. in the Sundarbans, Bangladesh

Mangroves throughout the world are threatened by environmental changes apart from anthropogenic disturbances. Many of these changes may inhibit the growth and survival of mangrove species. To understand and predict the effects of global change on mangrove forests, it is necessary to obtain insights on the growth dynamics of mangroves in relation to environmental factors. This study was conducted on Sonneratia apetala, a mangrove species which grows under a range of salinity conditions across the Sundarbans in Bangladesh. We studied trees growing under respectively high, medium, and low salinity conditions based on the influence of freshwater discharge. First, the periodicity of radial growth across the year was detected by applying cambial analyses. Based on tree-ring analyses, we calculated the growth response of S. apetala to monthly variation in precipitation and temperature as well as river discharge, as a proxy for salinity. We found the cambium of S. apetala being active during the monsoon and post-monsoon period whereas it was dormant in the pre-monsoon. This periodicity in radial growth leads to the formation of distinct annual rings with ring boundaries being marked by radially flattened fibres. S. apetala trees growing under low salinity conditions generally show higher growth rates indicating the positive impact of river discharge, i.e. freshwater input on mangrove growth. Wet and warm conditions during the monsoon period positively affected S. apetala growth, especially in the low salinity zone. Our results show that salinity is the primary driver of growth dynamics of S. apetala in the Sundarbans. A gradual or seasonal increase in salinity, e.g. as a consequence of sea-level rise may therefore importantly alter the growth of this species, possibly leading to changes in mangrove forest dynamics and zonation

Assessing service availability and readiness to manage Chronic Respiratory Diseases (CRDs) in Bangladesh.

IntroductionChronic Respiratory Diseases (CRDs) are some of the most prevailing non-communicable diseases (NCDs) worldwide and cause three times higher morbidity and mortality in low- and middle-income countries (LMIC) than in developed nations. In Bangladesh, there is a dearth of data about the quality of CRD management in health facilities. This study aims to describe CRD service availability and readiness at all tiers of health facilities using the World Health Organization's (WHO) Service Availability and Readiness Assessment (SARA) tool.MethodsA cross-sectional study was conducted from December 2017 to June 2018 in a total of 262 health facilities in Bangladesh using the WHO SARA Standard Tool. Surveys were conducted with facility management personnel by trained data collectors using REDCap software. Descriptive statistics for the availability of CRD services were calculated. Composite scores for facility readiness (Readiness Index 'RI') were created which included four domains: staff and guideline, basic equipment, diagnostic capacity, and essential medicines. RI was calculated for each domain as the mean score of items expressed as a percentage. Indices were compared to a cutoff of70% which means that a facility index above 70% is considered 'ready' to manage CRDs at that level. Data analysis was conducted using SPSS Vr 21.0.ResultsIt was found, tertiary hospitals were the only hospitals that surpassed the readiness index cutoff of 70%, indicating that they had adequate capacity and were ready to manage CRDs (RI 78.3%). The mean readiness scores for the other hospital tiers in descending order were District Hospitals (DH): 40.6%, Upazila Health Complexes (UHC): 33.3% and Private NGOs: 39.5%).ConclusionOnly tertiary care hospitals, constituting 3.1% of sampled health facilities, were found ready to manage CRD. Inadequate and unequal supplies of medicine as well as a lack of trained staff, guidelines on the diagnosis and treatment of CRDs, equipment, and diagnostic facilities contributed to low readiness index scores in all other tiers of health facilities

Heat transfer enhancement and development of correlation for turbulent flow through a tube with triple helical tape inserts

Influence of triple helical tapes inserted for turbulent flow through a tube on heat transfer enhancement was studied experimentally. The triple helical tapes made of mild steel with different helix angles, alpha = 9 degrees, 13 degrees, 17 degrees, and 21 degrees were examined for Reynolds number ranging from 22,000 to 51,000. The experiment showed that the Nusselt number, effectiveness and friction factor for the inserts were found to be up to 4.5, 3.45 and 3.0 times, respectively, over the plain tube. The highest enhancement efficiency achieved was 3.7 for the inserts based on constant blower power. Finally, new correlations for predicting heat transfer and friction factor for turbulent flow through a circular tube fitted with the inserts were proposed