S. R. Ranganathan Learning Hub

This study unveils an innovative approach to fabricating H2S gas sensor prototypes for continuous monitoring, leveraging Pd-decorated CuCrO2-based metal oxide semiconductor (MOS) chemiresistors and artificial neural network-assisted impedance-based multivariate analysis. Sensors were exposed to H2S in cross-interfering environments containing humidity, NO2, NH3, CH4, H2, and CO2. Impedance-based parameters (Z, phase difference, Z′ and Z") obtained at various frequencies demonstrated that sensors were reproducible and selective for H2S detection. A neural network-based multilayer perceptron (MLP) regression model was trained with different impedance-based parameters to estimate the H2S concentrations. Continuous operation resulted in larger baseline variation for Z, Z′, and Z" readings; however, the measured phase difference values exhibited less depletion than other parameters. Furthermore, concerns about baseline changes were effectively addressed with a fine-tuned MLP model, which predicted both pure air and H2S atmospheres more correctly under cross-interfering and baseline-depleted conditions by employing phase differences at different frequencies as input. Possible reasons for the accurate prediction can be attributed to the confined behaviour of phase difference and discussed with the help of sensor statistical parameters such as mean variation, standard deviation and principal components. © 2024 Elsevier B.V.

Dissimilar metal welded (DMW) joint plays a crucial role in constructing and maintaining ultra-supercritical (USC) nuclear power plants while presenting noteworthy environmental implications. This research examines different welding techniques utilized in DMWJ, specifically emphasizing materials such as P91. The study investigates the mechanical properties of these materials, the impact of alloying elements, the notable difficulties encountered with industrial materials, and the concept of buttering. The USC nuclear power plants necessitate welding procedures appropriate for the fusion of diverse metal alloys. Frequently employed methodologies encompass shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), and flux-cored arc welding (FCAW). Every individual process possesses distinct advantages and limitations, and the choice of process is contingent upon various factors, including joint configuration, material properties, and the desired weld quality. The steel alloy known as P91, which possesses high strength and resistance to creep, is extensively employed in advanced ultra-supercritical (AUSC) power plants. P91 demonstrates exceptional mechanical characteristics, encompassing elevated-temperature strength, commendable thermal conductivity, and notable resistance against corrosion and oxidation. The presence of alloying elements, namely chromium, molybdenum, and vanadium, in P91, is responsible for its improved characteristics and appropriateness for utilization in (AUSC) power plant applications. Nevertheless, the utilization of industrial materials in DMW joint is accompanied by many noteworthy concerns, such as the propensity for stress corrosion cracking (SCC), hydrogen embrittlement, and creep deformation under high temperatures. The challenges mentioned above require meticulous material selection, process optimization, and rigorous quality control measures to guarantee the dependability and sustained effectiveness of DMW joint. To tackle these concerns, a commonly utilized approach referred to as buttering is frequently employed. When forming DMW joint in nuclear facilities, it is customary to place a buttering coating on ferritic steel. This facilitates the connection between pressure vessel components of ferritic steel and pipes of austenitic stainless steel. The primary difficulty in DMW joint manufacturing is in mitigating the significant disparity in material characteristics resulting from carbon migration and metallurgical alterations along the fusion interface between ferritic steel and austenitic stainless steel. The process of buttering entails the application of a compatible filler material onto the base metal before the deposition of the desired weld metal. The intermediate layer serves as a mediator, enhancing the metallurgical compatibility, diminishing the probability of fracture, and enhancing the overall integrity of the joint. Buttering is still a new research area with a wide scenario of scope in terms of development, which could revolutionize developing high-temperature. These long-term sustainable joints could serve under critical conditions like AUSC power plants and reduce CO2 emissions by increasing the overall efficiencies of the systems.

High-power lasers have been shown to be more effective for welding plates with thicknesses of 10 mm or greater. In the present research, a heat-resistant P92 steel plate was welded using the laser beam welding process. The laser-welded joint underwent mechanical testing and metallographic characterization in both the as-welded condition and after post-weld heat treatment (760 °C for 2 h). The macrostructure analysis revealed that the welded joint had full penetration with negligible internal defects. The widths of the heat-affected zone (HAZ), the weld metal at the top, and the weld metal in the root region were 1.77 mm, 3.83 mm, and 3.12 mm, respectively. Inhomogeneity in both the microstructure and microhardness was observed along the welded joint. The coarse-grained structure with negligible precipitates in the coarse-grained HAZ resulted in a maximum hardness of 432 HV, while a minimum hardness of 225 HV was measured in the inter-critical HAZ, likely due to the formation of a complex microstructure. Another important observation in the fine-grained HAZ and inter-critical HAZ was the presence of two types of grain boundaries: one decorated with a high density of precipitates and the other free from precipitates. This contributed significantly to the heterogeneity in the microstructure. The weld metal exhibited a lath-elongated martensitic microstructure, which showed significant hardness variation due to the presence of soft ferrite patches. The hardness of the untempered martensite in the weld metal ranged from 385 to 403 HV, with an average of 398 ± 7 HV. In contrast, the hardness of the soft ferrite patches was measured in the same range of 234–349 HV. The ultimate tensile strength and percentage elongation were 1014 ± 11 MPa and 27 ± 3%, respectively, which are significantly close to those of the P92 base metal, as fracture occurred in the P92 base metal. The Charpy toughness measured higher than the recommended value of 47 Joules, confirming the suitability of the welded joint for USC boiler applications. The PWHT significantly reduced the inhomogeneity in microstructure and mechanical properties, though some variation remained. There was a notable decrease in hardness for the weld metal, coarse-grained HAZ, and fine-grained HAZ after PWHT, while the hardness of the delta ferrite patches and inter-critical HAZ remained relatively unaffected, leading to continued microstructural heterogeneity. The tempering of martensite due to PWHT resulted in a drop in ultimate tensile strength and an increase in percentage elongation, with failure still occurring in the P92 base metal in the PWHT condition. Additionally, Charpy toughness increased significantly after PWHT, confirming the applicability of the PWHT for welded joints of P92 steel before final application. A good correlation between microstructure and mechanical properties was established based on these findings. © Wroclaw University of Science and Technology 2025.

Non-steroidal anti-inflammatory drugs (NSAIDs) are recommended to treat moderate-to-severe pain. Previous studies suggest that NSAIDs can suppress cellular proliferation and elevate apoptosis in different cancer cells. Ketorolac is an NSAID and can reduce the cancer cells' viability. However, molecular mechanisms by which Ketorolac can induce apoptosis and be helpful as an anti-tumor agent against carcinogenesis are unclear. Here, we observed treatment with Ketorolac disturbs proteasome functions, which induces aggregation of aberrant ubiquitinated proteins. Ketorolac exposure also induced the aggregation of expanded polyglutamine proteins, results cellular proteostasis disturbance. We found that the treatment of Ketorolac aggravates the accumulation of various cell cycle-linked proteins, which results in pro-apoptotic induction in cells. Ketorolac-mediated proteasome disturbance leads to mitochondrial abnormalities. Finally, we have observed that Ketorolac treatment depolarized mitochondrial membrane potential, released cytochrome c into cytoplasm, and induced apoptosis in cells, which could be due to proteasome functional depletion. Perhaps more in-depth research is required to understand the details of NSAID-based anti-proliferative molecular mechanisms that can elevate apoptosis in cancer cells and generate anti-tumor potential with the combination of putative cancer drugs. © 2024 International Union of Biochemistry and Molecular Biology.

The development of advanced hydrogen (H2) sensors is crucial for ensuring the safe handling of H2, widely regarded as an optimal energy carrier to address the ongoing energy crisis. The development of H2 detection equipment is critical because of increasing H2 production from water electrolysis, H2 fuel cells, and other H2 businesses. The creation and characterization of palladium-anchored NiO-ZnO thin films for H2 gas sensing applications are investigated in this work. We fabricated the thin films using sputtering techniques to ensure a uniform distribution of dopants and effective anchoring of Pd (0.31 wt%). The results revealed that the Pd (0.31 wt%) anchored 4 wt% NiO-ZnO thin films demonstrate significantly improved sensitivity, selectivity, and response-recovery times compared with the NiO-ZnO variant. The combined effects of Ni and palladium anchoring, which enhance the adsorption and dissociation of H2 molecules, are responsible for this enhancement. This, in turn, increases the charge carrier concentration and alters the electrical resistance of the films. We found that the Pd (0.31 wt%) anchored NiO-ZnO thin films worked best at 150°C. They were able to detect 65 % of 50 ppm H2 with a response time of about 48 s and a recovery time of about 216 s. The results show that Pd (0.31 wt%) anchored NiO-ZnO thin films could be used as reliable and effective sensors for finding H2 gas. These sensors could be used in environmental monitoring, renewable energy, and safety in the workplace. These films present a promising solution for advanced gas sensing technologies due to their enhanced performance, ease of fabrication, and scalability. © 2025 Elsevier B.V.

The advanced ultra-supercritical (A-USC) power plant system is anticipated to become India's next-generation base-load power station. To adopt AUSC technology, dissimilar welded joints (DWJs) between heat-resistant steels and the nickel-based alloys, using the nickel-based fillers, will need to be implemented. However, failure of dissimilar welded joints from P92 steel base metal or the heat affected zone (HAZ) has been commonly observed under high-temperature creep conditions. In the present study, the creep rupture behaviours and rupture mechanisms of DWJ between the Ni-based alloy Inconel 617 and heat-resistant P92 steel with Inconel 617 (ERNiCrCoMo-1) filler metal were investigated. Creep tests were conducted at 650 °C in the stress range of 100–150 MPa. To examine the creep rupture behaviour of the DWJ samples, optical microscopy (OM), scanning electron microscopy (SEM) and microhardness tests were performed. Cross-sectional images of the fractured creep specimens tested under various operating conditions revealed failures originating from distinct locations, including the P92 base metal and the inter-critical heat affected zone (HAZ). The specimen tested at 650 °C/150 MPa exhibited failure originating from the P92 base metal, whereas the specimen tested at 650 °C under the stress range of 100–130 MPa showed failure from the inter-critical heat affected zone (ICHAZ). The failure from P92 BM was primarily governed by plastic deformation, with the growth and coalescence of dimples ultimately resulting in trans-granular fracture. The specimens tested at 650 °C/100–130 MPa, which failed from the ICHAZ, exhibited a typical Type IV inter-granular failure. This failure mode is primarily attributed to matrix softening in HAZ, weakening of the boundaries, coarsening of the precipitates, and the evolution of intermetallic Laves phases. The specimen that failed in the stress range of 100–130 MPa exhibited a high density of microvoids in the ICHAZ, along with a few microvoids in the FGHAZ. The weld metal showed negligible degradation in microstructure, while the hardness study revealed a significant increase in hardness with an increase in rupture time, i.e., a decrease in applied stress and it was attributed to evolution of the new carbide phases in weld metal. Coarsening of the carbide precipitates was observed in each zone of the HAZ of P92 steel as well as in the base metal. The EDS study of the fracture tip and the FGHAZ/ICHAZ of the specimen that failed under stresses of 100 MPa and 120 MPa confirmed the evolution of intermetallic Laves phases. High magnification SEM images confirmed that triple boundaries are preferential locations for microvoid nucleation. The failed specimen showed the presence of microvoids near the carbide precipitates, with a large density of both coarse and fine precipitates confirmed all around and inside the microvoids. The ICHAZ and FGHAZ confirmed the formation of fine prior austenite grain boundaries (PAGBs) during the welding thermal cycle, which exhibited a lower density of carbide precipitates and this played a major role in Type IV failure. © 2024 Elsevier Ltd

Open Educational Resources (OER) has emerged in the last two decades with the swift growth of technology and its interventions in education. The Open Educational Resources (OER) have become popular among the educators. The primary objective of this study is to analyse global research trends on open educational resources. This analysis aims to understand the research landscape better, identify significant trends, and support informed decision-making. For this study, the data was derived from the Scopus scientometric database covering the period of 2013 to 2022. A total of 669 publications with 8332 citations were found during the search. Most publications published on the subjects are in social science (54%), followed by computer science (18%) and engineering (6%). Burgos, Hilton, and Wiley were the most prolific and impactful authors. It was found that for effective and impactful collaboration in two and three authors, 3.23 is the highest collaborative index, 0.90 is the collaborative degree, and 0.60 is the collaborative coefficient in 2022. The highly cited paper, “Ocean Basin Evolution and Global-Scale Plate Reorganization Events since Pangea Breakup by RD Muller, “ was published in 2016 and received 689 citations. The journal “International Review of Research in Open and Distance Learning” was the most preferred source. Also, highly productive institutes with Open Educational Resources, funding agencies and countries were observed.

HfO2 is one of the most widely studied materials for resistive switching, owing to its CMOS compatibility and scalable performance. However, HfO2-based memristors suffer from stochastic filament formation, high device-to-device variability, and limited analog tunability due to abrupt and uncontrolled conductive filament growth, which limits their suitability for neuromorphic computing applications. Moreover, they often require external active electrodes like Ag or Cu to induce reliable switching, limiting material flexibility and integration. To overcome these challenges, AgHfO3-x is investigated, a silver-containing perovskite that inherently supports uniform and stable analog switching without relying on active metal electrodes. Oxygen vacancies formed during deposition, together with lattice silver, create hybrid filaments that drive resistive switching. To enhance reliability, oxygen vacancies are suppressed by introducing additional oxygen during deposition, leading to more stable switching and an improved ON/OFF ratio. Beyond reliable memory behavior, the AgHfO3-x memristor demonstrates synaptic functionalities essential for neuromorphic computing. The device exhibits analog modulation of conductance in response to voltage pulse protocols, effectively emulating key biological learning processes such as potentiation, depression, and paired-pulse facilitation. Furthermore, the device shows associative learning through a Pavlovian conditioning protocol, highlighting its potential as a hardware-implemented artificial synapse in next-generation brain-inspired systems. © 2025 Elsevier B.V., All rights reserved.

The study aims to explore the microstructure and mechanical characteristics of the gas tungsten arc welded joint in heat-resistant P92 steel under varying heat-treatment conditions. The welded joint undergoes tempering at 760 °C for 90 min, employing different cooling methods such as air cooling, furnace cooling, and water quenching. The welded joint were examined utilizing field emission scanning electron microscopy (FE-SEM) and optical microscopy. To assess the impact of heat treatment on mechanical properties, room-temperature and high-temperature tensile testing, microhardness testing, and Charpy impact toughness testing was performed. The fractured tensile and impact tested specimen was subjected to SEM characterization to investigate the fracture mode and failure mechanism. Among different heat-treatment conditions, the tempering process at 760 °C/90 min with air cooling exhibited the optimal combination, showcasing a tensile strength of 631 MPa, hardness of 284 ± 5 HV, and Charpy impact toughness of 142 ± 7.5 J. © 2025 Elsevier B.V., All rights reserved.