Browsing by Author "Vishwakarma P.K."
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Item Energy transfer characteristics in Tb(III)?2,5-dihydroxybenzoic acid complex(Elsevier Ltd, 2024) Vishwakarma P.K.; Rai S.B.; Bahadur A.Energy transfer through organic sensitization to ligand-centred Ln3+ ions is crucial for developing multifunctional materials with high brightness and good quantum yield from an application perspective. Gentisic acid (2, 5-Dihydroxybenzoic acid), as organic biomolecule is well known as the side minor metabolite of Salicylic acid/Aspirin and often used for palliative treatment. As fluorescence probes, significant optical absorption of 2, 5-DHBA in deep UV region fluoresce in near visible region and have also been employed to sensitize REs ions through metal-organic complexation. The present work emphasizes on the fluorescence assessment of DHBA, DHBA:Tb3+, PHEN:Tb3+, and DHBA/PHEN:Tb3+ complexes in PVA matrix as well as in aliphatic solvents. UV irradiation of DHBA embedded in PVA matrix or alcoholic solvent results in a vivid green emission of Tb3+ via linker-to-metal energy transfer (5D4?7F0-6). Moreover, the addition of PHEN pairing with DHBA:Tb3+ doped PVA matrix culminated in a broadened stimulus region (deep UV harvesting) and proficient energy transfer. Quantum Yield assessment revealed about the efficacy of DHBA is approximately 59 %, whereas for the optimized DHBA:Tb3+ in PVA matrix is about the 22 %. Colour tunability with Tb3+ concentrations, as well as the consequence of PHEN's as extended energy harvesting possibility, make it suitable for potential applications in optoelectronic devices, green LEDs, security inks, and biomarkers, etc. � 2024 Elsevier B.V.Item Engineered ultra-luminous La/YPO4:Eu3+ nanophosphors for advanced security ink and latent fingerprint (LFPs) detection(Elsevier Ltd, 2024) Kumar P.; Vishwakarma P.K.; Rai S.B.; Bahadur A.Designing versatile NPs for multifarious applications is crucial for achieving an array of criterion in realm, including improving efficiency, inexpensiveness, flexibility, least power consumption, etc. Facile hydrothermal treatment of La/YPO4:Eu3+ NPs yields composite phase growth signifying even-sized NPs with the requisite elemental composition. Relative CTB predominates in LaPO4:Eu3+; while luminescence of YPO4:Eu3+ is notably higher when stimulated by atomic lines. Nevertheless, La/YPO4:Eu3+ NPs exhibit adequate luminescence under both CTB and 394 nm (7F0?5L6) excitations, evincing intrinsic QY (63.91 %) with relatively large lifetime (?6 ms) of 5D0 states, substantiated by J-O analysis. Designed NPs is readily cling to friction ridge skin residues demonstrating the efficient LFPs development through the �powder dusting approach� on various substrate. NPs conjugated PVC gold medium and aqueous PVA were effectively used for security encryptions using the screen-printing technique. Reddish-orange emission with different excitation probabilities resulting in high QY emphasizes them in a class of futuristic versatile materials with potential applications in security ink, LFP development, LEDs, and display devices. � 2024 Elsevier B.V.Item Eu3+ activated gadolinium oxide quantum dots: Biocompatible red luminescent phosphor for photonic, latent fingerprint imaging, and anticancer therapy(Elsevier Inc., 2024) Kumar K.N.; Vijayalakshmi L.; Vishwakarma P.K.; Saijyothi K.; Lim J.; Siddiqui M.R.In this study, we employed a straightforward chemical reduction method to synthesize Gd2O3 quantum dots (QDs) doped with Eu3+ ions, yielding a remarkable red emission. X-ray diffraction (XRD) analysis confirmed the cubic structure of both pristine and Eu3+ doped Gd2O3 QDs. Characterization of particle size and elemental composition was accomplished through Transmission Electron Microscope (TEM) and X-ray photoelectron spectroscopy (XPS), respectively. Photoluminescence analysis under UV excitation revealed a blue emission at 436 nm for the undoped Gd2O3 QDs. Furthermore, room temperature photoluminescence analysis was conducted on the undoped Gd2O3 quantum dots (QDs) with a UV excitation source. While Gd2O3 QDs emitted a blue light at 436 nm under 396 nm illumination, the Eu3+ doped Gd2O3 QDs exhibited a striking red luminescence under the same 394 nm wavelength. The red luminescence was notably enhanced in Gd2O3 QDs containing 0.5 mol% Eu3+ ions, although concentration quenching was observed when the concentration exceeded this level. A transfer of energy from pristine Gd2O3 QDs to Eu3+ ions was observed, leading to color purity exceeding 80.8% in the optimized sample. Notably, the 0.5 mol% Eu3+-doped Gd2O3 QD phosphor displayed non-cytotoxicity on C2C12 muscle myoblast cells while demonstrating remarkable cytotoxicity against MDA-MB-231 human breast cancer cells. This versatile material holds great promise for applications in latent fingerprinting, security coding, labeling, anticancer therapies, bio-imaging, and the advancement of lanthanide-doped QD phosphors for a wide range of photonic and biomedical applications. � 2024 Elsevier Inc.Item Europium-Doped lanthanum oxide quantum dots: A promising quantum dots for latent fingerprint detection and photonic applications with remarkable red luminescence and biocompatibility(Elsevier Ltd, 2024) Kumar K.N.; Vijayalakshmi L.; Vishwakarma P.K.; Saijyothi K.; Lim J.; Siddiqui M.R.We employed a facile chemical reduction method to synthesize La2O3 quantum dots (QDs) doped with Eu3+ ions, resulting in a vivid red emission. X-ray diffraction (XRD) confirmed a cubic structure for both undoped and Eu3+ ions-doped La2O3 QDs. Transmission Electron Microscope (TEM) and X-ray photoelectron spectroscopy (XPS) assessed particle size and elemental composition, respectively. Photoluminescence analysis revealed blue emission at 432 nm for undoped La2O3 QDs under UV excitation and enhanced red luminescence for Eu3+-doped QDs, peaking at 394 nm excitation with an optimal Eu3+ ion content of 0.5 mol%. Colorimetric analysis demonstrated over 90 % color purity for the optimized sample. Lifetime studies probed red emission dynamics. The optimized QDs were employed for latent fingerprint (LFP) detection via powder dusting, showing high sensitivity, selectivity, and reliability. Cytotoxicity testing on mouse muscle myoblast cell lines (C2C12) confirmed noncytotoxicity and biocompatibility, endorsing their potential in various applications like latent fingerprinting, bioimaging, labeling, and security coding, thereby advancing lanthanide-doped QD phosphor development. � 2024 Elsevier LtdItem Vanadium disulfide nanosheets based membrane for filter application(Taiwan Institute of Chemical Engineers, 2024) Patel A.K.; Vishwakarma P.K.; Giri R.; Srivastava A.Background: Surface and groundwater resources are being significantly contaminated by organic pollutants, particularly diverse organic dyes released by the textile industry, thereby posing a considerable threat to aquatic ecosystems. Methods: we describe the development of a vanadium disulfide (VS2) membrane using a simple vacuum-assisted filtration method. Significant findings: It demonstrated impressive rejection rates for 10 ppm methylene blue (MB) solutions (92.5 %, 95.3 %, and 96.8 %) and 10 ppm methylene violet (MV) solutions (96.1 %, 97.3 %, and 98.1 %). These notable outcomes are credited to the pivotal role of the layered structure of the VS2 membrane, with thicknesses of ?44 ?m, 56 ?m, and 68 ?m, respectively. The water flux of these membranes exhibited a range of ?1300, 1350, and 1400 L m?2 h?1 for the MB solution. For the MV solution, the water flux ranged around ?1100, 1150, and 1200 L m?2 h?1. Further, it highlights the efficient filtration performance of these membranes for both MB and MV solutions. The membrane's highly efficient separation performance not only holds promise for various filtration applications but also establishes it as an innovative and effective solution in the continuous global endeavors to address water pollution. � 2024
