Bharathidasan University

Improving the performance of DSSCs relies on engineering photoanodes that can efficiently harvest photons, promote dye adsorption and inhibit recombination of charges. To address these challenges, DSSCs using Cu:Nb2O5 films as photoanode have been fabricated and their photovoltaic performance was investigated. XRD confirmed the retention of orthorhombic Nb2O5 with lattice distortion arising from Cu doping. Morphological examination revealed nanopore formation and increased particle size upon doping. Contact angle and AFM results showed that Cu doping promoted hydrophilicity and surface roughness that favours dye loading and electrolyte penetration. PL quenching upon Cu doping confirmed effective suppression of charge carrier pair recombination. The outcomes reveal that 5 wt% Cu:Nb2O5 photoanode based DSSC exhibited the best PCE of 8.82% with longer electron lifetime (16.61 ms) and reduced recombination resistance (21.06 Ω) compared to the pristine system 7.05%. Thus, Cu doping boosts its photovoltaic function, positioning Cu:Nb2O5 as workable photoanode for high performance DSSCs.

Escalating depletion of the non-renewable resources and the crisis of global pollution creates a critical demand for advanced technologies and innovations in material sciences. In response, scientists are increasingly adopting the biological systems as inspiration for the development of sustainable and next generation materials. This review elucidates the concept of employing microalgae and cyanobacteria as living, photosynthetic substrates for the development of biomimetic systems and biomaterials. The organisms render a driving force for the engineered living materials emulating the natural biological mechanisms such as photosynthesis, carbon fixation, biomineralization, environmental sensing and resilience over hostile conditions. Besides, microalgae and cyanobacteria are crucial in the advancement of sustainable technology, reinforcing the generation of sustainable biomaterials for various applications including environmental biosensing, drug delivery systems and tissue oxygenation. Moreover, diverse biologically active frameworks, three-dimensional bioprinting, self-healing construction materials illustrates their potential of biomimicry versatility. Despite the barriers in the material stability and scalability persists, the integration of synthetic biology and artificial intelligence/machine learning provides adequate strategies to break through these constrains. By exploiting the intrinsic potential of these organisms, it is possible to replace the extractive material systems with the regenerative systems which ultimately accelerate the circular bioeconomy and redefine sustainability in biotechnology.

Europium-doped urea-assisted TiO2 (Eu:U-TiO2) nanoparticles were synthesized via a hydrothermal method with Eu doping levels of 1, 3, and 5 wt%, together with undoped U-TiO2 as a reference. Structural, morphological, surface, and optical properties were systematically characterized. Photocatalytic activity was assessed under natural sunlight via the degradation of methylene blue (MB), acid black 1 (AB 1), and reactive red 120 (RR 120). The 3 wt% Eu:U-TiO2 catalyst exhibited superior performance, achieving near-complete degradation of MB (10 ppm) and degradation efficiencies of 81.06% for AB 1 (20 ppm) and 63.28% for RR 120 (50 ppm) within 90 min under optimized conditions (pH 9, 20 mg catalyst per 100 mL). Kinetic analysis followed pseudo-first-order behavior, with the highest rate constant observed for the 3 wt% Eu-doped sample. In parallel, antibacterial activity against both Gram-positive and Gram-negative bacteria demonstrated a marked enhancement for Eu-doped samples compared to undoped U-TiO2. Radical scavenging experiments and GC-MS analysis identified O-2(center dot)- and (OH)-O-center dot radicals as the dominant reactive species responsible for dye mineralization. Overall, the optimized 3 wt% Eu:U-TiO2 functions as a multifunctional material, integrating efficient sunlight-driven photocatalysis with significant antibacterial activity, and shows strong potential for combined environmental remediation and biomedical applications.

We investigate the occurrence of extremely large amplitude intermittent oscillations and transient dynamics in a silicon-based doubly clamped nanoelectromechanical system (NEMS) resonator driven by external periodic forcing. The system exhibits sudden, extensive amplitude variations induced by changes in the external periodic excitation. These large amplitude variations are characterized by analyzing the local maxima of the time series over an extended duration of time, up to the order of 10( 6 )normalized time units. The intermittent large amplitude oscillations satisfy the criteria for superextreme events and are further examined through their probability distribution functions. In addition, the peaks of intermittent oscillations that surpass a significant threshold are analyzed in terms of their inter-event intervals and total number of such events. Besides, the transient extreme events, arising under a different set of system parameters, are also studied, with their statistical distributions evaluated both with and without transients. Also, we included two-parameter phase diagrams to distinguish between regions associated with superextreme events and those exhibiting no such events. Further, we have also examined the effect of noise with varying control parameters. This study advances the understanding of unusual dynamical behaviors in NEMS resonators and underscores their potential relevance for future technological applications.

Marine macroalgae are increasingly utilized in functional foods and pharmaceuticals; however, their tendency to bioaccumulate heavy metals poses potential consumer health risks. This study assessed the concentrations of nine heavy metals (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn) in green, brown, and red macroalgae collected from ten coastal regions across Palk Bay and the Gulf of Mannar. Findings indicated significant metal concentrations, notably Arsenic (71.06 ± 0.12 µg/g) and Copper (127.71 ± 0.04 µg/g), with several species exceeding international food safety limits for As, Cd, and Pb. Species-specific accumulation was evaluated using the Metal Pollution Index (MPI). Enteromorpha fluxiosa (4.634) and Lobophora variegata (3.704) exhibited the highest MPI values, while Ulva lactuca and Porphyra indica showed negligible accumulation. Health risk assessments revealed that E. fluxiosa, Sargassum wightii, and Portieria hornemannii pose significant non-carcinogenic risks, as their Hazard Index (HI) values exceeded the safety threshold (HI > 1), primarily driven by arsenic and copper levels. In contrast, U. lactuca and Gelidiella acerosa maintained lower HI values, suggesting higher safety for human consumption. Statistical analyses, including Cluster Analysis and PCA, differentiated two primary groups: green algae with lower accumulation and red and brown algae with higher levels attributed to complex cell wall compositions. PCA identified Cd, Cu, Zn, Pb, and Co as primary drivers of species distribution, positioning U. lactuca and S. wightii as effective bioindicators. These results underscore the critical necessity for regular monitoring and stringent regulatory frameworks to ensure the safety of seaweed-derived products.