Spectrochemical, biological, and toxicological studies of DDT, DDD, and DDE: An in-silico approach

Pesticides are used to control the various pests and disease carriers. Degradation and/or biotransformation alter their chemical and toxicological nature. An attempt has been taken to investigate the physicochemical, spectral, and toxicological nature of DDT [1, 1'-(2, 2, 2-trichloroethylidene) bis(4-chlorobenzene)] and its major derivatives. DDT is transformed into DDD [l, l-dichloro-2, 2-bis(p,p-chlorophenylethane)], and DDE [l, l-dichloro-2, 2-bis(p,p-chlorophenylethylene)] under reductive dechlorination conditions. They last longer in the fatty tissue due to fat-soluble features, and exhibit some harmful effects on the environment and biological systems. Herein, density functional theory along with the CAM-B3LYP/6-311g ++ (d, p) basis set has been employed to investigate their physicochemical, and spectral properties. In-silico methods were incorporated to evaluate their biological, and toxicological properties. Molecular docking and nonbonding interaction calculations were performed to investigate their binding properties and mode(s) of action against the human estrogen receptor (PDB ID: 6PYF), and serine/threonine-protein kinase PIM-2 (PDB ID: 2IWI). Further, molecular dynamics simulation was performed to check the deformability and interactions of protein and amino acid residues, respectively. ADMET (absorption, distribution, metabolism, excretion, and toxicity) and PASS (prediction of activity spectra for substances) predictions were performed to compare their biological and toxicological properties. DDT has the highest free energy, dipole moment, and chemical reactivity; meanwhile, DDE and DDD have the highest binding affinity against both proteins. All the compounds exhibit hepato-toxicological, neuro-toxicological, and carcinogenic properties which depict their toxicological level. Based on their studied parameters, this study can help to increase awareness and provide a deeper understanding of the biochemical, and toxicological impacts on the environment and biological system

Impact of Urbanization on Urban Heat Island Intensity in Major Districts of Bangladesh Using Remote Sensing and Geo-Spatial Tools

Urbanization is closely associated with land use land cover (LULC) changes that correspond to land surface temperature (LST) variation and urban heat island (UHI) intensity. Major districts of Bangladesh have a large population base and commonly lack the resources to manage fast urbanization effects, so any rise in urban temperature influences the population both directly and indirectly. However, little is known about the impact of rapid urbanization on UHI intensity variations during the winter dry period in the major districts of Bangladesh. To this end, we aim to quantify spatiotemporal associations of UHI intensity during the winter period between 2000 and 2019 using remote-sensing and geo-spatial tools. Landsat-8 and Landsat-5 imageries of these major districts during the dry winter period from 2000 to 2020 were used for this purpose, with overall precision varying from 81% to 93%. The results of LULC classification and LST estimation showed the existence of multiple UHIs in all major districts, which showed upward trends, except for the Rajshahi and Rangpur districts. A substantial increase in urban expansion was observed in Barisal > 32%, Mymensingh > 18%, Dhaka > 17%, Chattogram > 14%, and Rangpur > 13%, while a significant decrease in built-up areas was noticed in Sylhet 10 °C, Chattogram > 9 °C, and Barisal > 8 °C compared to other districts due to dense population and unplanned urbanization. We identified higher LST (hotspots) zones in all districts to be increased with the urban expansion and bare land. The suburbanized strategy should prioritize the restraint of the high intensity of UHIs. A heterogeneous increase in UHI intensity over all seven districts was found, which might have potential implications for regional climate change. Our study findings will enable policymakers to reduce UHI and the climate change effect in the concerned districts