National Institute of Technology, Andhra Pradesh

An innovative reheat Brayton-Regenerative Kalina-Vapor absorption refrigeration integrated system was investigated from energy, exergy, and environmental perspectives. The system model, developed in matlab with temperature-dependent thermophysical properties and considering combustion dissociation, was subjected to parametric analysis and multi-objective optimization. The influence of Brayton cycle pressure ratio (r(p)), Brayton turbine inlet temperature (BTIT), and Kalina turbine inlet temperature (KTIT) on power output, energy utilization factor (EUF), power density (PD), exergy efficiency, dissociation effects, and specific carbon emission rates (SCERs) was assessed. The results show that increasing r(p) from 3 to 46 at BTIT 1100 degrees C and KTIT 340 degrees C enhances EUF from 19.8% to 49.98%, exergy efficiency from 14% to 42.41%, and PD from 64.9 to 1838.4 kW-s/m(3). Higher r(p) suppresses dissociation, as reflected by an increase in the CO2/CO ratio from 0.78 to 2.27. Increasing BTIT enhances efficiency and PD, but promotes dissociation. Compared to the Brayton cycle, the integrated system shows a substantial reduction in SCER from 2.04 to 0.65 kg/kWh at an r(p) of 3 and BTIT of 1100 degrees C. Finally, two multi-objective optimization problems were formulated and solved using genetic algorithm. The Pareto frontiers were evaluated using three decision-making approaches to identify the optimal solution. The study concludes that optimized combinations of pressure ratio and BTIT not only maximize energy utilization but also suppress dissociation, establishing the system as a unique pathway for efficient and eco-friendly power-cooling cogeneration.

The modern lifestyle has significantly increased plastic usage, leading to a surge in plastic waste accumulation in landfills, where physical, chemical, and biological degradation generate microplastics (MPs). These MPs originate from diverse polymer types such as polypropylene, polyethylene, polystyrene, and polyethylene terephthalate, with their release strongly influenced by waste composition, landfill management practices, and aging processes. The highest reported concentration of MPs in landfill leachate was 33,213 items/L in Guangzhou, China, while the lowest ranging from 0.16 to 1.10 items/L, was observed in Lahti, Finland. MPs migrate into adjacent soil, groundwater, and adjacent surface water systems, thereby altering soil physicochemical properties, disrupting aquatic food webs, and acting as carrier of co-contaminants. Their environmental fate and toxicity are governed by MPs property and surface aging, which enhances sorption capacity and bioavailability across ecosystems. Remediation technologies, including physical separation, chemical, and biological treatment, have demonstrated removal efficiencies up to 99

Efficient thermal energy storage is essential for enhancing the reliability and responsiveness of solar thermal systems. Phase Change Materials (PCMs), particularly sugar alcohols such as D-mannitol and erythritol, provide high latent heat capacity but suffer from inherently low thermal conductivity, resulting in slow solidification rates. To address this limitation, the present study proposes a novel dual nano-enhanced PCM (NEPCM) system embedded within a concentric cylindrical enclosure and augmented by tapered crossbar fins to improve solidification performance. A baseline configuration consisting of a tapered two-fin design with decreasing width (TTFDW) is introduced, against which various enhanced configurations are compared. The thermal behavior of dual PCMs is analyzed under different fin geometries, which include two and four fins with either increasing or decreasing width, and hybrid nanoparticle pairs at volume fractions (cent) up to 6%. Numerical simulations indicate that both fin structure and nanoparticle dispersion significantly influence solidification dynamics. Among the tested designs, the tapered four-fin configuration with increasing width (TFFIW) exhibited the most efficient solidification, owing to its improved conductive pathways and symmetric heat distribution. Relative to the TTFDW baseline using SiO2-Al2O3 at cent = 2%, the TFFIW configuration with SiO2-SWCNT at cent = 6% achieved a reduction in solidification time by 23.33%, and average temperature by 7.16% in the outer PCM and 6.28% in the inner PCM. The superior thermal properties of hBN and SWCNT further contributed to enhanced radial heat conduction and cooling uniformity. Solidification and temperature contours confirmed that increasing fin number and optimizing nanoparticle volume fractions reduced thermal gradients and minimized residual liquid zones, particularly in the inner PCM region. This integrated NEPCM-fin strategy offers a scalable and effective pathway for accelerating solidification and boosting thermal responsiveness in solar thermal storage systems. The proposed configurations show great promise in enhancing charge-discharge rates, cyclic durability, and overall performance of advanced latent heat energy storage technologies, particularly in concentrated solar power (CSP) plants where rapid and uniform thermal discharge is essential. The findings also highlight the potential for deployment in industrial-scale thermal receiver modules and other high-temperature latent heat storage units designed for continuous renewable energy utilization.

In this work, we have developed and systematically evaluated a new fluorescent chemosensor, DQCS, capable of selectively and sensitively detecting Cd2+, Co2+, and Ni2+ ions. The sensing performance was investigated in a DMSO-H2O (9:1, v/v) medium, where DQCS exhibited significant fluorescence quenching upon interaction with these target ions. Selectivity studies confirmed minimal interference from other common metal ions, highlighting the high specificity of the DQCS probe. Job's method indicated that the probe interacts with the metal ions in a 1:1 molar ratio. At the same time, fluorescence titration experiments yielded low limits of detection values of 4.75x10-5 M for Cd2+, 3.63x10-5 M for Co2+, and 2.99x10-5 M for Ni2+, indicating high sensitivity. Furthermore, binding constants of 1.57x104 M-1 (Cd2+), 4.32x104 M-1 (Co2+), and 6.43x104 M-1 (Ni2+) was obtained. Among the tested ions, Ni2+ exhibited the highest binding constant and strongest interaction with DQCS. Theoretical studies using DFT and TD-DFT methods provided insight into the electronic and structural changes upon metal coordination with the probe. A notable change in molecular electrostatic potential (ESP) and a reduced HOMO-LUMO energy gap collectively confirmed enhanced charge transfer interactions, especially in the case of Ni2+ complex. Overall, the combined experimental and computational results indicate that DQCS is an effective, multi-responsive fluorescent sensor with significant potential for tracing specified metal ions in environmental and analytical samples.

In this work, the structural, magnetic and electrical transport properties of the quaternary Heusler alloy FeRuMnSi have been thoroughly studied experimentally using a polycrystalline sample, in addition to theoretical calculations to investigate its structural and magnetic properties. According to first-principles calculations, the ordered structure as well as disordered structure exhibits both ferromagnetic and antiferromagnetic exchange interactions at low temperatures. These expectations are corroborated by the observation of comparable competitive ferromagnetic and antiferromagnetic interactions in our disordered system, indicating that these interactions are intrinsic to the system. dc magnetization measurements reveal that the compound undergoes an antiferromagnetic transition at approximately 175 K. A glassy magnetic phase is present in the low temperature region, as evidenced by the irreversibility between field-cooled and zero-field-cooled magnetization curves, which is noticeable below 150 K. The frequency-dependent peak observed at 8.5 K in the ac susceptibility, along with the absence of a A-shaped anomaly in the heat capacity, confirms the presence of cluster glass behavior in the system. Additionally, longitudinal resistivity data show an upturn below 22 K, which is attributed to electron-electron interaction arising from structural disorder.