Noakhali Science and Technology University

Pollution from potentially toxic elements (PTEs) threatens coastal wetlands, which support biodiversity and ecological services. The ICP-OES analysis of sediment samples from coastal wetlands on the Sitakunda coast assessed PTE contamination and ecological risks. The sediment sample mean PTE concentrations were ordered in decreasing order: Cr (58.96 ± 6.86 mg/kg) > Ni (46.74 ± 5.09 mg/kg) > Cu (41.1 ± 11.40 mg/kg) > Pb (13.37 ± 5.09 mg/kg) > As (8.68 ± 1.37 mg/kg) > Hg (0.37 ± 0.042 mg/kg) > Cd (0.32 ± 0.04 mg/kg), exceeding sediment threshold impact levels. PTE concentrations for most of the metals across wetlands were mangrove > saltmarsh > mudflat > sandflat. Each wetland had pollution load index (PLI) values below 1, indicating no pollution, and was in the following order: mangrove > salt marsh > mudflat > sand flat. Cd exhibited substantial contamination factor (CF) values, while all other wetland metals were low. Geoaccumulation Index (I_geo) found negligible contamination in all wetlands (I_geo < 0). Hg had EF values <1 across all wetlands, indicating natural sources. As, Cd, Cr, Cu, Ni, and Pb EF values >1 in all wetland types, indicating anthropogenic sources. All metals across studied wetlands showed low ecosystem risk except Hg and Cd, which exhibited moderate ecological risks. A correlation matrix, cluster analysis, and principal component analysis showed substantial correlations (p < 0.05) between metals and listed anthropogenic sources. We recommend planting artificial mangroves in coastal areas to trap and stabilize PTE pollution, a natural and effective remedy.

Triboelec. nanogenerators (TENGs) have gained significant devotion in the field of energy extraction and self-powered sensor development due to their unique combination of contact electrification and electrostatic induction.Over the past few years, researchers have made significant advancements in material synthesis along with device technol.This has led to the development of multiple methods, concepts, and theor. analyses aimed at improving the TENG performance.This review delivers an inclusive overview of the research progress in enhancing the output performance of TENGs using various approaches.The overview covers four main aspects: surface material modifications of TENGs, structural engineering strategy, power management, and applications.Initially, this section provides an introduction to the fundamental principles, operational methods, theor. framework, and material choices for TENGs.Addnl., the different surface modification and treatment methods for TENGs are categorized.Surface materials can be modified through different treatment methods, which are categorized into phys. and chem. alterations.Next, we will explore various techniques to enhance the output power of TENGs using structural engineering methods.These techniques include employing multilayer structures, creating a TENG stack, and designing electrodes for TENGs.Furthermore, this text provides a summary of the current techniques used to enhance the efficiency of TENGs in terms of power supply, including power management and charge boosting.In addition, the assessment also discusses the use of TENGs in emerging fields involving wearable electronics, machine learning, artificial intelligence, and self-powered applications for sensors.Finally, considering the current advancement, we thoroughly analyze the significant issues and propose future research directions and challenges in a systematic manner.

High-shore intertidal gastropods experience energy-demanding thermo-dehydrative stressful conditions during air emersion, related to their vertical position and the habitat heterogeneity. Simultaneously, these gastropods are forced to downregulate metabolism when resting in air to limit dehydration and ensure energetic homeostasis under conditions of constrained food (energy) intake, due to prolonged inactivity. We investigated this apparent conundrum by studying the temporal patterning of metabolic depression and the influence of depressed metabolism on heat tolerance of the tropical high-shore snail, Planaxis sulcatus, during progressive air emersion. We compared cardiac thermal performance (a proxy for metabolic performance) of snails pre-exposed to different periods of air emersion (field fresh, 5 d and 10 d) and different levels of dehydration and heat stress, mimicking naturally sunned or shaded resting habitats. Compared to early air emersion, long resting periods under benign (shaded) conditions suppressed cardiac thermal performance and elevated heat tolerance, responses mostly not modified by dehydration or heat stress. Cardiac (energetic) suppression was temporally idiosyncratic among individuals, becoming more uniform with longer air emersion. Reanalyzed data comparing higher and lower metabolic (energetic) states across the treatments showed greater heat tolerance in lower-energetic snails. The apparent energetic conundrum of simultaneously needing to support energetically-demanding protective heat tolerance and energetically-conserving metabolic depression can be explained by an early highly energy-demanding preparatory stage, which hardens snails for the duration of aestivation, irrespective of the resting habitat conditions. Our observed temporal patterning of metabolism provides an excellent framework for molecular and cellular investigation of high-shore snails.