Showing papers by "Dilip K. Maiti published in 2021"

Nonconventional biocompatible macromolecular AEEgens for sensitive detections and removals of Cu(II) and Fe(III): N and/ or O donor(s) selective coordinations of metal ions

Abstract: For sensitive detections and repetitive exclusions of excess Cu(II)/ Fe(III) from hazardous effluents and high-contrast time dependent Madin-Darby canine kidney cell imaging by photobleaching resistant durable non-aromatic biodegradable biocompatible fluorogens, two non-conventional purely aliphatic macromolecular luminogens, i.e., butyl-2-propenoate-co-butyl 3-acrylamidopropanoate-co-prop-2-enamide (i.e., BP-co-BAP-co-PE, M1) and ethylene glycol methacrylate-co-ethylene glycol 3-acrylamido-2-methylpropanoate-co-prop-2-enamide (i.e., EGM-co-EGAMP-co-PE, M2), were prepared through the in situ anchoring of third acrylamido-ester comonomers during polymerization of two monomers and the optimization of ex situ added monomer ratios. Structures of as-synthesized nonconventional luminogens, in situ anchored BAP/ EGAMP, and aggregation-enhanced emissions/ AEEs were understood by exploring microstructures through XPS, 1H/ 13C NMR, FTIR, UV–vis, TGA, DSC, HRTEM, DLS, fluorescence imaging, fluorescence lifetime, and network parameters. The emission properties, fluorescence quenching, and exclusions of Cu(II) and Fe(III) were investigated in organic solvents and pure water, inferred through computational studies of M1/ M2 and Cu(II)-M1/ Fe(III)-M2 complexes. Herein, the strong coordination of O/ N donor(s), i.e., –CONH2, –CONH–, and –COOCH2–, with Cu(II) and O donors, i.e., –COOCH2– and –CONH–, with Fe(III) in Cu(II)-M1 and Fe(III)-M2 complexes, respectively, were examined through XPS, FTIR, TG, and SEM analyses of those complexes; pseudosecond order model fitting; and activation energies of adsorption. The limits of detection of M1 and M2 were 1.69 × 10–7 and 1.88 × 10–7 M, respectively. The adsorption capacity maxima of M1 and M2 under optimum conditions were 130.64 and 100.04 mg g−1, respectively, within 5–50 ppm and at 303 K for 0.01 g M1/ M2.

Complementary amide-based donor-acceptor with unique nano-scale aggregation, fluorescence, and band gap-lowering properties: a WORM memory device.

Abstract: Organic fluorescent semiconducting nanomaterials have gained widespread research interest owing to their potential applications in the arena of high-tech devices. We designed two pyrazaacene-based compounds, their stacked system, and the role of gluing interactions to fabricate nanomaterials, and determined the prospective band gaps utilizing the density functional theory calculation. The two pyrazaacene derivatives containing complementary amide linkages (-CONH and -NHCO) were efficiently synthesized. The synthesized compounds are highly soluble in common organic solvents as well as highly fluorescent and photostable. The heterocycles and their mixture displayed efficient solvent dependent fluorescence in the visible region of the solar spectrum. Notably, the compounds were associated through complementary NH•••O = C type hydrogen bonding, π-π stacking, and hydrophobic interactions, and thereby afforded nanomaterials with a low band gap. Fascinatingly, the fabricated stacked nanomaterial system exhibited resistive switching behavior, leading to the fabrication of an efficient write-once-read-many-times memory device of crossbar structure.

Heat transfer and entropy generation in a MHD Couette–Poiseuille flow through a microchannel with slip, suction–injection and radiation

Abstract: Flow, heat transfer and entropy generation in a vertical microchannel made of two parallel porous plates (the injection plate kept at rest while the suction plate is moving in upward/downward direction) under the combined action of buoyancy force and transverse magnetic field are studied. Variable pressure gradient (favorable/adverse) due to Couette–Poiseuille (C–P) flow is considered here. This is one of the fundamental problems of applied science and engineering. Slip conditions for the velocity at plates are implemented for both moving-plate directions and pressure gradients with the help of classical C–P flow. The basic equations are solved numerically by using Runge–Kutta–Fehlberg method along with shooting technique. Numerical results are in concordance with previously published results for specific cases. The present results are frequently compared with those of the classical C–P flow. Influence of operational parameters (plate movement, pressure gradient, injection–suction rate, slip length, Grashof Number, temperature ratio (between hotter to colder side) and viscous dissipation effect) on the flow and heat transfer characteristics (velocity, temperature, Nusselt number (Nu) distribution, entropy generation and Bejan Number) are investigated here. An effort is made to search singularity in the variation of Nu with some parameters, and find the parameters’ values at which the global entropy is minimally generated in the channel. Finally, a critical analysis is conducted on the individual contribution of irreversibilities due to heat flow, fluid friction and Joule heating to the total entropy generation.

A Novel Quinoxaline-Rhodamine Conjugate for a Simple and Efficient Detection of Hydrogen Sulphate Ion

Abstract: This work presents the development of a quinoxaline and rhodamine conjugate system that acts as a colorimetric chemosensor for hydrogen sulfate (HSO4−) ions in methanol media. This sensor has been characterized both theoretically and experimentally. The detection limits for HSO4− are small as 0.71 µM and 3.8 µM for the absorption and emission experiments, respectively. The effectiveness of the probe in recognizing HSO4− both in gel and solid phase is evaluated as well. Thus, this works presents a simple strategy to detect the environmental HSO4− pollutant event at tiny concentrations.

Eco-friendly cost-effective energy-storage device for the benefit of society

Abstract: Energy plays a key role in the development of modern civilization. The power generation and power consumption problems are solved by the energy-storage device technologies. Many capacitors, supercapacitors are already used for energy-storage devices, but our modern civilization demands low cost and environmentally friendly nanomaterials for high-tech devices. Recently, eco-friendly way to use sustainable energy is an important phase for modern energy economy. Continuous use of electronic devices is essential in the daily life of the highly demanding modern society. An essential requirement of fresh and proficient energy-storage technology will give us a substitute solution. Herein we discuss the low-cost eco-friendly nanomaterials for effective energy-storage devices, charge–discharge capacity as supercapacitors to help in daily human life.

Effect of ionic liquid on the micellization behavior of bile salts in aqueous medium

Abstract: Interfacial and aggregation behavior of sodium cholate (NaC) and sodium deoxycholate (NaDC) in aqueous ionic liquid (IL, 1-butyl-3-methylimidazolium tetrafluoroborate) medium were investigated. Stu...

Arsenic pollution and human health issues – special reference to Bengal Delta

Abstract: Groundwater arsenic contamination and its effects on human health in the Bengal basin is a saga of 45 years of negligence (1976–2020). The situation is at its worst in the Bengal delta, with over 100 million people living in zones with arsenic above 0.05 mg/L. Natural groundwater arsenic contamination and the sufferings of people as a result has become a crucial water-quality problem in many parts of the world, but especially in the Bengal delta. Today, consumption of drinking water is the raised up source of arsenic in arsenic affected areas. Using arsenic-contaminated groundwater in cultivation has led to arsenic accumulation in soil and therefore in crops and vegetables grown in these soils. The people living arsenic-endemic regions are severely malnourished or undernourished and tend to be highly susceptible to health issues (e.g., arsenicosis, cancer, cognitive disorders, etc.).

Nanotools and devices in solar power energy

Abstract: Photovoltaic solar cells are a promising fill-in energy resource that can help to control the global climate change by transforming sunlight energy directly into electrical energy. Nowadays, modern science is inclined toward nanomaterial-based solar cells, owing to the continuous rise of global interest in renewable solar power energy. Nanomaterials can form cost-effective and flexible solar devices, having power conversion efficiency superior to any other solar cell. The use of nanomaterial-based solar cells can reduce dependence on natural resources such as oil, coal, gases, and mined uranium, which can improve the economy of a country and protect the world environment by minimizing the release of environmentally toxic chemicals. The semiconductor nanomaterials are highly used as active materials for solar cells. Even many organic and organic–inorganic hybrid nanomaterials are efficient for this purpose. Thus, nanotechnology-based high-tech solar energy conversion and storage devices can constitute efficient systems for the generation, storage, and transportation of energy.

Environmental problems and management aspects of waste electrical and electronic equipment and use of clean energy for sustainable development

Abstract: E-waste is a popular, informal name for electronic products nearing the end of their “useful life.” E-waste contains many hazardous substances, which have been found to be extremely dangerous to human health and the environment. E-waste is often disposed of under less than ideal safety conditions. Various forms of electric and electronic equipment that have ceased to be of value to their users or no longer satisfy their original purpose are treated as E-wastes. The electrical wastes are TV, refrigerator, lights, etc., whereas the electronic wastes are computers, mobiles, LEDs, etc. It has been already reported in India that computer devices account for nearly 70% of e-waste, 12% comes from the telecom sector, 8% from medical equipment, and 7% from electric equipment. The government, public sector companies, and private sector companies generate nearly 75% of electronic waste, with the contribution of the individual household being only 16%. Computers, televisions, VCRs, stereos, copiers, and fax machines are common electronic products. Many of these products can be reused, refurbished, or recycled. There is an up-gradation done to this E-waste garbage list, which includes gadgets like smartphone, tablets, laptops, video game consoles, cameras, and many more. Improper dumping and burning of E-wastes can lead to toxic chemicals leaking into the air, water, and soil. Potential health outcomes from e-waste exposure include changes in thyroid functions, poor neonatal outcomes, including spontaneous abortions, stillbirths and premature births, behavioral changes, malfunction of the lung, DNA damage, and child's growth (for lead). The processes used to recycle and dispose of e-waste in India have led to a number of harmful environmental impacts. In the near future, the increasing energy consumption will force us to use clean and renewable energy sources, which include solar, wind, hydrothermal energy, and biomass. Among these options, solar energy stands out as the most reliable choice to fulfill our energy requirement. The toxic, polluting sources are coal, oil, and gas. Solar energy has the ability to produce electricity and heat water. Solar energy holds enormous potential. Generating electricity from clean renewable sources increases our opportunities to displace costly polluting oil and gasoline. Cost-effective, clean, and renewable sources of electricity are getting more acceptances, while dirtier sources like coal are losing their acceptability due to the harmful residues. The power sector is a leading source of cancer-causing air pollution and one of the largest sources of carbon dioxide. Clean Energy is the energy that is produced through the processes to omit greenhouse gases or any other pollutants as residual elements and prevent the pollution of the atmosphere. The advantages of clean energy are that it reduces our reliance on Fossil Fuels and tones down climate change. Even inorganic solar cells like silicon solar cells that are not efficient left silicon wafer as residues. The silicon wafer is hazardous for soil and if it burns then it pollutes the air also. Organic and hybrid solar cells that contain glass substrates only are the best clean energy so far as those devices do not leave any harmful residues and are also recyclable.

Interfacial and Aggregation Behaviour of Sodium Dodecyl Sulphate Induced by Ionic Liquids.

Abstract: Aggregation studies of anionic surfactant sodium dodecyl sulphate (SDS) was investigated in aqueous 1-butyl-3-methylimidazolium chloride [bmim]Cl and N-butyl-N-methyl pyrrolidinium tetrafluoroborate [bmp]BF4 ionic liquid (IL) solutions respectively. Systems were studied by surface tension, conductance, UV-VIS absorption/emission spectroscopy and dynamic light scattering. Critical micelle concentration (CMC) values gradually decreased with increasing IL concentration which indicates synergistic interaction between ILs and SDS. Gibbs free energy change results demonstrated spontaneous micellization induced by ILs; however the effect of ILs were not similar to the corresponding regular salts (NaCl and NaBF4). Aggregation number (n) of micelles, determined by fluorescence quenching method, indicate that the 'n' values increase with increasing ILs concentration, induced by the oppositely charged IL cation. Size of the micelles, determined by dynamic light scattering studies, increased with increasing ILs concentration, which were due to the formation of larger aggregates; the aggregates are considered to be comprised of the anionic surfactant with a substantial proportion of ILs cation as the bound counter ions. Such studies are considered to shed further light in the fundamentals of IL induced micellization as well as in different practical applications.