Browsing by Author "Darshan Singh"

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Characterization and radiative impact of dust aerosols over northwestern part of India: a case study during a severe dust storm
(Springer-Verlag Wien, 2016) Atinderpal Singh; Shani Tiwari; Deepti Sharma; Darshan Singh; Suresh Tiwari; Atul Kumar Srivastava; Neeraj Rastogi; A.K. Singh
The present study focused on examining the impact of a severe dust storm (DS) on aerosol properties over Patiala (30.33°N, 76.4°E), a site located in the northwestern part of India during 20th–23rd March, 2012. On 20th March, average PM10 mass concentration increased abruptly from 182 to 817 µg m−3 along with significant increase in the number density of coarser particles (diameter >0.45 µm). During DS, spectral aerosol optical depth (AOD) increases significantly with more increase at longer wavelengths resulting in weak wavelength dependence (AOD at 380 nm increases by ~210 % and at 870 nm by ~270 % on 20th March). Significant decrease in Ångström exponent (AE; α380–870) from 0.56 to 0.11 and fine-mode fraction (FMF; PM2.5/PM10) from 0.49 to 0.25 indicates dominance of coarser particles over the station. Net short wave (SW) radiation flux has been decreased by ~20 % and single scattering albedo (SSA675) has been increased from 0.86 (19th March) to 0.90 (20th March). This observation is attributed to additional loading of scattering type aerosols on arrival of DS. Wavelength dependence of SSA reverses during DS and it increases with wavelength due to dominance of coarse-mode particles. Atmospheric aerosol radiative forcing (ATM ARF) during DS ranged from +45 to +77 W m−2, consequently heating the lower atmosphere up to 2.2 K day−1. Significant atmospheric heating rate due to severe dust storm may affect the regional atmospheric dynamics and hence the climate system. © 2016, Springer-Verlag Wien.
Future perspectives on QDs embedded nano-fibrous materials as high capacity sustainable anode for Na-ion batteries technology
(Springer Nature, 2023) Sunil Kumar; R.N. Rai; Darshan Singh; Anees A. Ansari; Youngil Lee; Laxman Singh
Abstract: Electrode functionalization (shape-selective materials) has transformed the energy storage and production technology in the modern age of developing Batteries science. Sodium-ion batteries are promising electrochemical energy supply system suitable alternative to Li-ion batteries, particularly for low cost, earth abundance Na ion, high structural stability, and better functioning behavior at cooler temperatures. In Na-ion batteries (NIBs), lowest potential electrode (negative electrode) act as primary charge carrier and thermodynamically susceptible to reduce alkali Na +. However, conventional anode material suffers from volume variation and stability issues. Quantum dots (QDs) size (1–10 nm) supported nanofiber (1D) functions as high rate redox-active materials due to synergistic interaction and structural confinement effect. Present perspective shed light on various structural interactions, thermodynamic interactions and interfaces which may lower the energy barrier (activation energy) during electrode electrochemical performance. Quantum dots provide functional sites in nanofiber resulting in expansion of Na+ storage and sodiation reaction. Thus, structural and chemical variation unveil future research for high capacity, robust Na+ storage, and better thermodynamic stability of fibrous Na-ion anode materials to upgrade the futuristic electrode technology. Graphical abstract: [Figure not available: see fulltext.] © 2023, The Author(s), under exclusive licence to The Materials Research Society.