From theoretical model to experimental realization, the bound state in the continuum (BIC) is an emerging area of research interest in the last decade. In the initial years, well-established theoretical frameworks explained the underlying physics for optical BIC modes excited in various symmetrical configurations. Eventually, in the last couple of years, optical-BICs were exploited as a promising tool for experimental realization with advanced nanofabrication techniques for numerous breakthrough applications. Here, we present a review of the evolution of BIC modes in various symmetry and functioning mediums along with their application. More specifically, depending upon the nature of the interacting medium, the excitations of BIC modes are classified into the pure dielectric and lossy plasmonic BICs. The dielectric constituents are again classified as photonic crystal functioning in the subwavelength regime, influenced by the diffraction modes and metasurfaces for interactions far from the diffraction regime. More importantly, engineered functional materials evolved with the pure dielectric medium are explored for hybrid-quasi-BIC modes with huge-quality factors, exhibiting a promising approach to trigger the nanoscale phenomena more efficiently. Similarly, hybrid modes instigated by the photonic and plasmonic constituents can replace the high dissipative losses of metallic components, sustaining the high localization of field and high figure of merit. Further, the discussions are based on the applications of the localized BIC modes and high-quality quasi-BIC resonance traits in the nonlinear harmonic generation, refractometric sensing, imaging, lasing, nanocavities, low loss on-chip communication, and as a photodetector. The topology-controlled beam steering and, chiral sensing has also been briefly discussed.

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Thermoelectric technology is gaining paramount importance for solar energy conversion and electricity production to increase green energy resources with high efficiency. An enormous amount of research is being carried out for engineering various solar absorbers using tailored materials and structures for solar energy harvesting. However, the methods to achieve cost-effective light absorbers are still challenging. Here we present a perfect broadband solar absorber for efficient photothermal conversion of sunlight employing a low-cost ultraviolet laser-induced graphene (UV-LIG) prepared on a polymer material using the conventional direct laser writing method. Recently the LIG generation employing the direct laser writing method has been recognized as a straightforward and low-cost technique to generate graphene foam. We have patterned the UV-LIG to produce a two-dimensional grid pattern to limit the reflection losses. The resulting UV-LIG surface exhibits very high absorption (>99%) for the entire spectral range of sunlight. Significantly, the absorber attains a temperature of 90.4 °C under 1 sun irradiation within a response time of less than 60 s. Further, we have exploited the extraordinary photothermal property of the patterned UV-LIG together with a commercially available thermoelectric generator (TEG) to make a solar thermoelectric generator (STEG) device with excellent output performance. Our investigation perceived that the structured UV-LIG absorber-based STEG has excellent power generation capability compared to the STEGs with other absorbing materials. Remarkably, we could achieve an output voltage of 273.9 mV under 1 sun irradiation, one of the highest among the recent STEGs, primarily due to the enhanced absorption of absorbing material. These results suggest that the proposed versatile and robust solar energy harvesting technology can be employed for solar–thermoelectric conversion systems.

In the present study, we have identified a R2R3 type MYB protein from Withania somnifera, i.e., MYB34 (WsMYB34), known for plant development and stress tolerance. MYB transcription factors (MYB TF) have been widely implicated in conferring biotic and abiotic stress tolerance in medicinal plants. To validate this notion, we have analyzed the impact of different concentrations of NaCl on Withania somnifera and the potential of MYB protein in affecting the growth and development by acting as TFs in regulating the expression of defence-related genes and secondary metabolites. Since structural and functional characteristics of MYB TF in W. somnifera remains largely unknown, in-silico analysis was exploited to understand conserved binding motifs, phylogeny, 3-D structure, and role in regulating stress-responsive genes. Based on the domain analysis and phylogenetic assessment, WsMYB34 was found to be a R2R3 type MYB protein, which is phylogenetically closer to Solanum pennellii. In addition, interaction analysis depicted the binding capacity of WsMYB34 protein on the promoter region of a triterpenoid synthesising gene viz; CYP85A69 (having CAACTG cis-regulatory sequence). The comparative microarray analysis also offered the role of WsMYB34 in abiotic stress tolerance. Exposure to NaCl imposed increased withanolide and flavonoid contents and significantly up-regulated the expression of key genes for withanolide and WsMYB34 gene by 0.93–3.68 fold 2.61–3.47 fold respectively. The CYP85A9 gene was also induced by 3.47 fold at 150mM NaCl. In addition, NaCl also affected growth and biochemical behaviour of W. somnifera. Thus, these findings depicted the role of WsMYB34 protein in plant salt tolerance.