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TuDR is the digital asset management system which integrates the intellectual output in the form of research articles, PhD theses, and M.Tech / M.E. theses. TuDR facilitates the sharing and exchange of intellectual output of the university.

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Recent Submissions

Psychomotor Vigilance across Young and Older adults in the presence of Affective Primes
(2026-06-04) Kaur, Pavneet; Nigam, Richa
Sustained attention is an important part of everyday cognitive functioning, yet the factors that shape it remain incompletely understood, particularly the role of emotional processes that operate below the threshold of conscious awareness. The present study examined how subliminal emotional priming influences psychomotor vigilance performance across two distinct age groups: young adults and older adults. Using a mixed factorial design, 120 participants were exposed to happy or sad facial primes in a standard task of psychomotor vigilance. The primed condition of the task was compared with a non-primed condition of the task comparing the performance of younger versus older adults. Reaction time, inter-stimulus interval sensitivity, and attentional lapses served as the primary performance indices. It was suggested that due to motivational shift with aging, older adults would respond faster to trails following positive primes (than negative primes) when compared with younger adults. The suggestion is embedded in the classic socio-emotional selectivity theory which suggests a motivational shift occurring with aging due to which older adults prioritize positive emotions over negative or neutral emotions/information. The findings are expected to shed light on how preconscious emotional information interacts with the sustained attention, and whether age-related shifts in affective processing style alter the way subliminal cues are integrated into moment-to-moment vigilance.
Age related differences in affective face visual search among pareidolias under varying levels of stimulus prevalence
(2026-06-02) Saluja, Hargun; Nigam, Richa
The goal of the current study was to examine how visual search performance is affected by how often the target appears (in low prevalence and high prevalence conditions) and emotional expression (angry vs happy faces). Visual search is an important cognitive function in which people look around them for a specific target among group of distractors. Earlier studies have shown that when the targets are rare, people are more likely to miss them. This is known as the Low Prevalence Effect (LPE). This study further explored the interactions between age and emotional content and its impact. In the current study participants performed a visual search task in which they were required to identify happy or angry faces among non-face distractors (pareidolia images). The task consisted of both low and high prevalence conditions that is sometimes the target appeared rarely and sometimes very often. The participants had to press “M” key whenever they saw a face and “Z” whenever thet thought that the face is not present. For both target present and absent trials reaction time and accuracy was noted. We also wanted to know when people would give up looking for the face when it was not there. So we also noted the reaction time for target-absent low prevalence trials. This was done to calculate the Quitting Threshold. In target-present high prevalence trials reaction time was used to assess the processing speed. The results showed that participants were less accurate in finding targets during low prevalence conditions supporting the presence of Low Prevalence Effect. Additionally reaction time patterns indicated that when targets are rare participants stopped searching. Emotional expression played a role as well as seen by the differences in the speed and accuracy for identifying angry and happy faces. Also compared to younger participants, older adults tended to search for longer periods of time and had slower reaction times, indicating age related variations in visual search behaviour. 6 Overall the findings suggest that both target frequency and emotional content influence how people search for and detect targets and that these processes may change with age
Measuring inhibitory control in emotionally dysregulated young and old adults using Stop Signal Paradigm
(2026-06-04) Sembi, Gurnoor Kaur; Nigam, Richa
Inhibitory Control is the ability to supress pre-initiated responses, a fundamental executive process sensitive to emotional context as well as age related cognitive change. Increasing evidence show how emotional valence and emotion regulation difficulties independently modulate inhibitory processes, however little research has studied these factors together in young and old adult sample. The present study fills in this gap by examining how emotional valence, age related differences and differences in emotional regulation among people together influence inhibitory performance using Emotional Stop Signal Paradigm. A sample 64 participants (30 young; 34 old) was assessed on task and difficulties in emotion regulation. Negative emotional conditions showed greater inhibitory control performance which was reflected by longer Stop Signal Delay (SSDs) and shorter Stop Signal Reaction Time (SSRT), indicating the increased caution of the cognitive system towards environmental threat. Older Adults exhibited longer SSRTs compared to young adults suggesting the age-related slowing of inhibitory mechanism. Importantly, young and old adults both were modulated by emotional valence in similar manner, that can be interpreted through the Socioemotional Selectivity Theory that reflects the. sophistication of emotion regulation resources with increase in age. Higher scores in difficulties in emotion regulation scale were associated with lower stop success, indicating that emotional dysregulation hampers the executive resources needed for efficient response inhibition. Taken together, these findings highlight the process of inhibitory control sensitive to emotional contexts, cognitive aging and individual regulatory capacity, unfolding a meaningful understanding of real-world processing of impulse control in emotional situations.
Preparation of protein-based bionanocomposites and evaluation of their physico-chemical properties
(2026-06-09) Sharma, Shreya; Pal, Bonamali; Das, Niranjan
The increasing accumulation of non-biodegradable plastics and the growing concerns related to environmental pollution and water contamination have created an urgent need for sustainable and multifunctional materials. In response to these challenges, the present research was undertaken to develop protein-based bionanocomposites (BNCs) with improved physicochemical characteristics for applications in biodegradable food packaging and adsorption-based environmental remediation. The detailedunderstanding of the structural characteristics, preparation approaches, applications, advantages, and existing limitations of bionanocomposite systems, which helped identify key research gaps and establish the foundation for the experimental work. Particular emphasis was placed on the utilization of renewable protein sources in combination with suitable nanofillers to improve the functional performance of biopolymer-based materials. Initially, SPI has emerged as a promising material in recent years because of its availability, sustainability, low cost, and favorable film-forming and processing characteristics. In the present work, novel SPI-based bionanocomposite films were fabricated by incorporating Mg–Al layered double hydroxide (LDH) at varying loadings (0%, 2%, 5%, and 9% w/w) through a straightforward solution-casting technique. The Mg–Al LDH was synthesized using a co-precipitation route with a molar ratio of 2:1. Structural and morphological characterization using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and thermogravimetric analysis (TGA) confirmed the intercalation and partial exfoliation of Mg–Al LDH layers within the SPI matrix. The extent of LDH particle agglomeration increased as the filler loading was raised from 0% to 9% (w/w). The resulting BNC films exhibited enhanced thermal stability. Their mechanical performance and biodegradation behavior were also evaluated. Tensile strength of the films containing 0%, 2%, 5%, and 9% w/w LDH were measured as 2.12 ± 0.25, 1.60 ± 0.15, 1.64 ± 0.08, and 1.58 ± 0.06 KN m g⁻¹, respectively. Notably, the SPI–Mg/Al LDH film with 5% loading demonstrated optimal mechanical properties; moreover, it was efficiently degraded in non-sterile soil. Building upon these findings, novel wheat gluten (WG)/Cloisite 30B (C30B) organoclay-based bionanocomposite films were fabricated using a solution-casting technique with varying C30B loadings (5%, 10%, and 15%). Structural and morphological analyses using XRD and FESEM confirmed the intercalation and partial exfoliation of C30B layers within the WG matrix. Among the prepared films, the WG–C30B 10% composition exhibited notable improvements in physicochemical properties, including reduced surface roughness, enhanced water barrier performance, and increased surface hydrophobicity. This BNC film demonstrated superior thermal stability. Mechanical testing revealed a significant enhancement in tensile strength, increasing from 0.70 ± 0.02 for neat WG films to 1.11 ± 0.01 for WG–C30B 10% films. Such films effectively inhibited the growth of some bacteria namely, Staphylococcus aureus and Salmonella enterica clearly indicating antibacterial properties. Shelf-life studies on green grapes were conducted under refrigerated (4 °C), ambient, and elevated temperature (42 °C) conditions. It was shown that the WG–C30B 10% film was effective in extending the shelf life up to 18 days under ambient conditions as compared to dip coated with WG-C30B 10% solution. Biodegradation studies demonstrated that over 50% of the BNC films were decomposed in agricultural soil within two weeks, while complete degradation occurred rapidly in sewage sludge soil. The prepared WG–C30B 10% film exhibited promising physicochemical, antibacterial, and biodegradation properties, clearly showing its potential for use in biodegradable food packaging applications. To expand the scope of practical application, protein-based biocomposites were further explored as adsorbent systems for contaminant removal. A sensitive UV–visible spectroscopic technique was successfully employed to detect tartrazine (Tr), an azo dye, in commercially available food products. The study evaluated the adsorption performance of soy protein isolate (SPI)/ZnAl layered double hydroxide (LDH)-based biocomposites for effective Tr removal. ZnAl LDH with a 3:1 molar ratio and SPI/ZnAl LDH biocomposites containing varying SPI loadings (0.25–3 g) were synthesized using a co-precipitation approach. Several techniques namely, XRD, FTIR, SEM, EDS, TGA, DSC, and BET analyses were used in order to characterize the BNC films in a comprehensive manner. The crystallinity index of the 2:1 SPI/ZnAl LDH biocomposite was determined to be 53.8 ± 0.416%. FTIR analysis confirmed the presence of characteristic amide I (C=O stretching at 1621 cm⁻¹) and amide II (N–H bending at 1521 cm⁻¹) functional groups, indicating successful incorporation of SPI. Under optimized conditions i.e. initial dye concentration of 18 mg L⁻¹, pH 2.0, adsorbent dosage of 5.0 mg, and contact time of 60 min, the 2:1 SPI/ZnAl LDH biocomposite remained effective in achieving 99.85% dye removal at ambient temperature. Thermodynamic and adsorption parameters revealed a spontaneous process (ΔG = −2.72 kJ mol⁻¹), with a maximum adsorption capacity (q_max) of 49.01 mg g⁻¹ and an adsorption equilibrium constant of 0.162 g mg⁻¹ min⁻¹. The adsorption behavior was aptly described by both Langmuir (R² = 0.9935) and Freundlich (R² = 0.9959) isotherm models, along with pseudo-second-order kinetics. The biocomposite demonstrated efficient Tr removal from commercial samples, achieving removal efficiencies of 81.43% for Mountain Dew, 79.21% for yellow candy, 77.85% for custard powder, and 75% for food dye wastewater. Moreover, the adsorbent retained approximately 73% efficiency after five regeneration cycles, indicating good reusability. Antimicrobial activity against Listeria species and Acinetobacter calcoaceticus was also observed. The SPI–LDH hybrid system showed potential for the removal of hazardous dyes from food products and wastewater. Overall, the findings of this work demonstrate that the integration of proteins with layered nanofillers offers an effective strategy for developing multifunctional bionanocomposites possessing improved thermal, mechanical, antimicrobial, biodegradable, and adsorption characteristics. These materials show strong potential as sustainable alternatives for food packaging and environmental applications.
Preparation of fly ash-TiO2-metal hybrid composites for adsorption and photocatalytic applications
(2026-06-05) Sharma, Ridhima; Pal, Bonamali; Barman, Sanghamitra
Abstract: Chapter-1 This chapter provides an overview of adsorption and semiconductor photocatalysis as effective strategies for wastewater treatment, with a focus on fly ash–TiO₂–metal–zeolite hybrid materials. It discusses the environmental impact of industrial effluents and the drawbacks of conventional remediation technologies. The chapter highlights the role of fly ash as an inexpensive, porous support, its functionalization with TiO2 to enhance photocatalytic activity, and subsequent performance improvements achieved through metal doping and zeolite incorporation. A critical review of recent studies illustrates how these components work synergistically to broaden light absorption, enhance charge separation, and improve catalyst durability for degrading dyes. Methods for material synthesis, structural and optical characterization, and performance evaluation are summarized. The chapter concludes by identifying existing research gaps and emphasizing the need for advanced hybrid composites capable of achieving superior efficiency under visible and solar light irradiation. Chapter-2 This study emphasizes the need to achieve both high photocatalytic efficiency and strong adsorption capacity in a catalyst to ensure complete removal of fuchsine blue dye (FB) from wastewater. In this work, TiO2 and fly ash–TiO2 composites (0.5–5wt%) were prepared using a sol–gel method combined with wet impregnation, and their performance was evaluated for combined processes of adsorption and photocatalytic breakdown of fuchsin blue dye. The materials were characterized using XRD, UV–DRS, SEM, EDS, Raman spectroscopy, and N₂ adsorption analysis. Adsorption and degradation experiments were conducted to evaluate the effects of pH (2–10), adsorbent dosage (1–9 mg), contact time (30–180 min), and initial dye concentration (5–30 mg/L) on FB dye removal efficiency. Among the tested samples, the 5 wt% fly ash–TiO2 composite exhibited the highest adsorption capacity of 20.32 mg/g and achieved 76% FB dye removal. These results indicate that adsorption occurs primarily through monolayer coverage on a homogeneous surface, in agreement with the Langmuir isotherm, and governed by pseudo-first-order kinetics. Under UV irradiation, the same 5wt% fly ash–TiO2 composite reached a maximum photocatalytic degradation of 88% after 180 minutes, following pseudo-first-order kinetics. The catalyst demonstrated excellent reusability, maintaining its dye removal performance consistent over five consecutive cycles. Chapter-3 In this study, copper (Cu) photo-deposited fly ash-TiO2 composites (FT-Cu0.5-2) with Cu content ranging from 0.5 to 2wt% were synthesized to evaluate their adsorption and photocatalytic activity toward the photodegradation of fuchsin blue (FB) dye under visible light as well as natural sunlight. Structural characterization was performed using X-ray diffraction (XRD) and diffuse reflectance spectroscopy (DRS), while morphological and surface chemical analyses were carried out through high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and N₂ adsorption Brunauer-Emmett-Teller (BET) analysis. These confirmed the successful fabrication of fly ash-TiO2 (FT) and Cu-modified composites (FT-Cu0.5-2). Copper nanoparticles, with sizes in the range between 7 and 17 nm, were uniformly distributed on the FT composite surface. The impact of various adsorption parameters, including FB dye concentration, adsorbent dose, solution pH, and contact duration, was systematically investigated. Following 180 minutes of adsorption in the dark, the 1wt% Cu-loaded FT composite (FT-Cu1) showed the highest dye removal efficiency of 77% and fitted well to the Langmuir adsorption model. A notable enhancement in photocatalytic activity was observed for FT-Cu1, which achieved 92% FB degradation under sunlight and 94% under visible light, compared to the unmodified FT catalyst with only 68% and 71% removal, respectively. This enhancement in removal efficiency is attributed to the synergistic interaction between Cu, fly ash, and TiO2 components. The presence of Cu improved the efficient separation of photogenerated charge carriers and expanded visible light absorption by introducing intermediate energy states within the TiO2 bandgap. The degradation pathway of FB dye was elucidated via trapping experiments using hole scavengers and detection of intermediate species through High-Resolution Mass Spectrometry (HRMS). Additionally, the FT-Cu composite exhibited strong photostability and could be reused effectively, maintaining approximately 83% degradation efficiency after five consecutive cycles, demonstrating its potential for sustainable treatment of organic contaminants. Chapter-4 In this work, copper photo-deposited fly ash–TiO₂ (FT-Cu1) composites were modified with ZSM-5 zeolite at loadings of 1%, 3%, and 5% by weight, designated as 1ZFT-Cu1, 3ZFT-Cu1, and 5ZFT-Cu1, respectively. These composites were investigated for their capability to adsorb and photo-catalytically degrade crystal violet (CV) dye under visible and solar light exposure. Characterization techniques, including UV-Vis diffuse reflectance spectroscopy (DRS), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and BET surface area analysis, revealed that the addition of ZSM-5 enhanced crystallinity, minimized particle aggregation, and increased visible light absorption by the composites. Among the samples, the 3wt% ZSM-5-loaded composite (3ZFT-Cu1) exhibited the best photocatalytic performance, achieving dye removal efficiencies of 98% under visible light and 95% under solar irradiation, using a catalyst dosage of 5 mg, initial dye concentration of 5 mg/L, a contact time of 180 minutes, and solution pH 9. The adsorption process fitted well with the Freundlich isotherm model, indicating multilayer adsorption, while the degradation kinetics followed a pseudo-first-order rate. The superior activity is credited to the synergistic interaction of copper doping, the porous structure of ZSM-5, and the fly ash support, which collectively enhanced light absorption and dye uptake. The 3ZFT-Cu1 composite also showed commendable stability, retaining 84% of its degradation efficiency after five cycles of reuse. Free radical trapping studies using hole scavengers elucidated the photocatalytic degradation pathway of CV dye, highlighting the composite’s effectiveness under visible light for potential wastewater treatment applications