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284 results on '"Tomar, Radha"'

2. A Numerical Study on Analysis of Reinforced Rock Slope

Author

Tomar, Radha, Tung, Smita, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Cui, Zhen-Dong, Series Editor, Lu, Xinzheng, Series Editor, Satyam, Neelima, editor, Singh, A. P., editor, and Dixit, Manish S., editor

Published
2025
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17. Europium Doped SrSnO3Perovskite: Structural, Spectroscopic, and Luminescent Characterization for Advanced Lighting Technologies and Beyond

Author

Bhat, Aadil Ahmad, Bi, Wengang, Ganie, Adil Shafi, Sofi, Shakeel Ahmad, Tomar, Radha, Abd-Rabboh, Hisham S. M., and Syed, Imam Saheb

Abstract

This study explores the incorporation of Eu3+ions into SrSnO3and their effect on the structural, spectroscopic, and luminescent properties. X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) analysis confirm the successful doping of Eu3+. Density functional theory (DFT) calculations reveal an indirect band gap, with an estimated experimental value of 2.8 eV for 5% Eu3+, as determined by diffuse reflectance spectroscopy (DRS). Photoluminescence (PL) analysis shows a red emission at 612 nm, corresponding to the 5D0→ 7F2transition of Eu3+ions. Under 256 nm UV excitation, the optimal luminescent properties were observed at 5 mol % Eu3+, displaying a predominant red emission at 612 nm attributed to the 5D0→ 7F2transition of Eu3+ions. The study found that emission intensity decreased beyond a certain concentration due to concentration quenching effects determined through Blasse equation. Judd–Ofelt intensity parameters were calculated from the emission spectra, and Ω2and Ω4, are (1.15 and 1.09) × 10–20cm2, respectively for 5% Eu3+doped SrSnO3. The emission properties for the 5D0→ 7F1,5D0→ 7F2,and 5D0→ 7F4emission transitions are also estimated with J–O parameters. The higher magnitude of branching ratios (58%) and emission cross sections (7.09 × 10–22cm2) suggest that the Eu3+doped SrSnO3perovskite may be suitable for efficient red emitting device applications. This research provides insights into the structural and spectroscopic properties of Eu-doped SrSnO3perovskites, highlighting their potential for advanced lighting technologies in agriculture and plant growth.

Published
2024
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27. Construction of C5‐Indole Unnatural Amino Acid Motifs via Diastereoselective Pd(II)‐Catalyzed β‐C(sp3)‐H Functionalization.

Author

Patel, Pooja, Babu, Srinivasarao Arulananda, and Tomar, Radha

Subjects
AMINO acid derivatives, AMINO compounds, AMINO acids, SMALL molecules, DRUG discovery, FRIEDEL-Crafts reaction, STEREOCHEMISTRY, ORGANIC synthesis
Abstract

We report the construction of C5‐indole unnatural amino acid derivatives via the diastereoselective Pd(II)‐catalyzed prochiral β‐C(sp3)‐H arylation of racemic (DL), and enantiopure L‐ and D‐carboxamides of amino acids with 5‐iodoindoles. Independently, indole‐based compounds and amino acid motifs are important small molecules in organic synthesis and drug discovery research. This report aimed to contribute to enriching the library of indole‐based unnatural amino acid derivatives. The synthesis of examples of C5‐indole motif‐installed amino acid derivatives comprising norvaline, phenylalanine, leucine, norleucine, 2‐aminooctanoic acid having anti‐stereochemistry was accomplished. The synthesis of the C5‐indole motif‐containing non‐α‐amino acid (aminoalkanoic acid) derivatives was also reported. The C−H arylation reactions of racemic and enantiopure carboxamides with 5‐iodoindoles afforded the corresponding indole unnatural amino acid derivatives with good diastereoselectivity (anti, dr>95 : 5 and enantiopurity (er up to 99 : 1). Removal of the directing group (8‐aminoquinoline), phthalimide group and preparation of indole amino acid esters and free amino group‐containing indole unnatural amino acid motifs were also shown. The utility of the methodology was shown by synthesizing indole motif‐containing pyrrolidone and peptide molecules. The stereochemistry of the major (anti) diastereomers was ascertained from the X‐ray structure of a representative compound. [ABSTRACT FROM AUTHOR]

Published
2024
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34. Hydrothermally grown Cu doped NiMnO3 perovskite nanostructures suitable for optoelectronic, photoluminescent and electrochemical properties.

Author

Upadhyay, Shilpi, Assadullah, Insaaf, and Tomar, Radha

Subjects
COPPER, ELECTRON-hole recombination, SEMICONDUCTOR materials, PEROVSKITE, BAND gaps, TRANSITION metal oxides
Abstract

Transition metal-based perovskites have emerged as highly promising and economically advantageous semiconductor materials due to their exceptional performance in optoelectronics, photovoltaic, photocatalysis, and photoluminescence. In this study, we employed a microwave-assisted hydrothermal process to produce a Cu-doped NiMnO3 nanocomposite electrode material. The appearance of a peak corresponding to the (110) plane with a 2θ value of 36.6° confirmed the growth of the rhombohedral NiMnO3 crystal structure. The presence of metal–oxygen bonds in NiMnO3 was confirmed through FTIR spectra. XPS validates the chemical composition, providing additional support for the results obtained from XRD and FT-IR analyses. FE-SEM affirmed the anisotropic growth of small sphere-like structures that agglomerated to form broccoli-like shapes. Cu doping modified the band gap, reducing it from 2.2 to 1.7 eV and enhancing its photoluminescent (PL) activity by introducing defects. The increase in PL intensity (visible light luminescent intensity) can be attributed to a concurrent rise in complex defects and the rate of recombination of electron–hole pairs. Finally, the electrochemical activity demonstrated the pseudo-capacitor behavior of the synthesized material, with capacitance values increasing as the copper (Cu) content in the parent lattice increased. [ABSTRACT FROM AUTHOR]

Published
2024
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