Solar energy is regarded as the finest clean and green energy generation method to replace fossil fuel-based energy and repair environmental harm. The more expensive manufacturing processes and procedures required to extract the silicon utilized in silicon solar cells may limit their production and general use. To overcome the barriers of silicon, a new energy-harvesting solar cell called perovskite has been gaining widespread attention around the world. The perovskites are scalable, flexible, cost-efficient, environmentally benign, and easy to fabricate. Through this review, readers may obtain an idea about the different generations of solar cells and their comparative advantages and disadvantages, working mechanisms, energy alignment of the various materials, and stability achieved by applying variable temperature, passivation, and deposition methods. Furthermore, it also provides information on novel materials such as carbonaceous, polymeric, and nanomaterials that have been employed in perovskite solar in terms of the different ratios of doping and composite and their optical, electrical, plasmonic, morphological, and crystallinity properties in terms of comparative solar parameters. In addition, information on current trends and future commercialization possibilities of perovskite solar have been briefly discussed based on reported data by other researchers.

Silver nanoparticles (AgNPs) are well-known for their distinctive optical, electronic, and antimicrobial properties, enabling versatile applications in biosensors, photonics, electronics, drug delivery, and antimicrobial treatments. The biological synthesis approach offers a sustainable and eco-friendly alternative to traditional physical and chemical methods. Metal and metal oxide nanoparticles synthesized from plant extracts are emerging as promising agents with notable medicinal potential. This study presents a cost-effective, simple, and eco-friendly approach for synthesizing silver nanoparticles (AgNPs) through the reduction of Ag⁺ ions to metallic silver (Ag⁰) using an aqueous extract of Alcea rosea leaves. The synthesized nanoparticles were characterized using various techniques, including UV–visible, FTIR, XRD, FESEM, and EDX. Biological activities were evaluated for their antioxidant, antibacterial, and anticancer assays. The AgNPs demonstrated moderate antibacterial activity against Staphylococcus aureus and Shigella sonnei, as evidenced by moderate minimum inhibitory and bactericidal concentrations, and mild DPPH free radical scavenging activity with an IC₅₀ value of 80.05 ± 1.53 µg/mL. The nanoparticles exhibited significant anticancer activity against cervical cancer cell lines, with an IC₅₀ of 54.46 ± 1.67 µg/mL. These findings suggest that the synthesized AgNPs have promising potential for medical applications, especially in drug development.

Lemongrass is one of the medicinal plants having significant applications to cure various diseases. This study aims at extracting essential oils from lemongrass plants and examining their antibacterial activity. The sample of lemongrass for this study was collected from Kailali District, Nepal. The leaves of lemongrass were collected, washed, cut into small pieces, and dried in the sun. Then pieces of lemongrass were steam distilled for about 4 hours using the Clevenger apparatus, and oil was extracted. The extracted essential oil was further utilized to study its antibacterial activity in human pathogens, namely Staphylococcus aureus (S. aureus: gram-positive bacteria), by Agar diffusion and broth dilution methods. It was found that the zone of inhibition for S. aureus in concentrations of 100%, 75%, 50%, and 25% was about 25 mm, 11 mm, 9 mm, and 0 mm, respectively. In addition, it is clear from this study that the gram-positive bacteria were sensitive to essential oils. The lowest and highest zones of inhibition were shown against S. aureus at 25% and 100% concentrations, respectively. The zone of inhibition at 100% concentration is 25 mm and at 25% concentration is 0 mm, so lemongrass oil is effective against drug-resistant organisms only at high concentrations.

Silver nanoparticles (Ag NPs) are well-known for their distinctive optical, electronic, and antimicrobial properties, enabling their versatile applications in areas such as biosensors, photonics, electronics, drug delivery, and antimicrobial treatments. The biological synthesis approach offers a sustainable and eco-friendly alternative to traditional physical and chemical methods. Metal and metal oxide nanoparticles derived from plant extracts are emerging as promising agents with notable medicinal potential. This study presents a cost-effective, simple, and eco-friendly method for synthesizing silver nanoparticles (Ag NPs). This method reduces silver ions into stable Ag NPs using an aqueous leaf extract of Alcea rosea . The synthesized Ag NPs were characterized using various techniques, including UV-visible, FTIR, XRD, FESEM, and EDX. The Ag NPs demonstrated notable antioxidant, antimicrobial, and anticancer properties. They exhibited excellent inhibition of DPPH free radical scavenging activity, with an IC ₅₀ value of 80.05 ± 1.53 µg/mL. Strong antibacterial activity was observed against gram-positive Staphylococcus aureus and gram-negative Shigella sonnei , with significant MIC and MBC values. Furthermore, the nanoparticles showed potent anticancer activity, with an IC₅₀ of 54.46 ± 1.67 µg/mL against cervical cancer cell lines. These findings suggest that the synthesized Ag NPs have promising potential for medical applications, especially in drug development.

Undesirable sound is called noise. Excessive amounts of sound in the environment causes noise pollution. Noise pollution is one of the major environmental problems in recent times especially in urban regions. This study aims to examine the noise levels near hospitals located in Dhangadhi Sub-Metropolitan City. A total of nine hospitals were selected for this study which are located in Dhangadhi Sub-Metropolitan City. The noise level was recorded in those hospitals in morning (8:00-10:00), day (14:00-16:00) and evening (17:00- 19:00) time. A digital sound meter was used to measure noise levels in the month of February 2024. This study showed that noise levels (Leq) at those hospitals were more than the prescribed noise level. In the selected hospitals higher noise levels was observed in those hospitals which are near the roads or highways. Less noise level was measured in the hospitals which are inside the road. This study Concluded that the high traffic of vehicles on the road, bad condition of the road, human crowds, and unnecessary use of horns are the major causes of noise pollution in those hospitals.

The clinical performance of standard chemotherapeutics is often limited by systemic toxicity and the rapid development of multidrug resistance. To address these challenges, we used an aqueous extract of Justicia adhatoda leaves to develop a sustainable, plant-based method for synthesizing Zinc Oxide (ZnO) and Silver (Ag) nanoparticles. This green approach provides a biocompatible alternative to traditional chemical methods, reducing hazardous waste. We characterized the resulting materials using XRD, FTIR, UV-Vis, FE-SEM, EDX, and Zeta potential analysis. Structural analysis confirmed that the synthesized ZnO nanoparticles formed a crystalline hexagonal wurtzite structure with an average particle size of 72.0 nm. In contrast, the Ag nanoparticles exhibited a face-centered cubic geometry with a mean particle size of 39.46 nm. Zeta potential measurements revealed high surface stability for both nanostructures, showing negative surface charges that prevent agglomeration. In the biological assay, ZnO NPs exhibited broader and more consistent antibacterial efficacy against Staphylococcus aureus and Klebsiella pneumoniae than Ag NPs in standard well diffusion. Time-kill kinetics further substantiated that ZnO NPs demonstrated more rapid, concentration-dependent bactericidal action over a 24-h window compared to Ag NPs. Conversely, MIC and MBC analyses showed that Ag NPs were highly effective against specific strains, such as S. aureus (1.56/3.125 µg/mL). Both nanostructures demonstrated potent, dose-dependent cytotoxicity against HeLa and A549 cancer cell lines. To the best of our knowledge, this is the first comparative study between ZnO and Ag nanoparticles synthesized from Justicia adhatoda under identical conditions. These findings highlight Justicia adhatoda as a powerful reducing and stabilizing agent, supporting the development of a scalable platform for multifunctional nanomaterials in targeted therapeutics.