Browsing by Author "Rohit Kumar Gupta"

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Electrochemical Hydrogen Production Using Carbon-Based and TMDs-Based Nanomaterials As Electrocatalysts
(World Scientific Publishing Co., 2024) Rohit Kumar Gupta; Prince Kumar Maurya; Ashish Kumar Mishra
The increasing global warming, population growth, and energy crisis promote the shift toward highly efficient, nontoxic renewable energy resources. Hydrogen energy is a promising solution to meet energy demand. Among different hydrogen production methods, electrochemical water electrolysis produces complete green hydrogen. Carbon- and transition metal dichalcogenides (TMDs)-based nanomaterials can be used as efficient electrocatalysts for hydrogen production due to their high conductivity, large accessible surface area, flexibility, and good stability in acidic/basic medium. In this chapter, we focus on the effect of morphology, doping, and heterostructure of carbon- and TMD-based electrocatalysts that enhance the performance of electrochemical hydrogen production. © 2024 World Scientific Publishing Company.
Persistent Health Issues, Adverse Events, and Effectiveness of Vaccines during the Second Wave of COVID-19: A Cohort Study from a Tertiary Hospital in North India
(MDPI, 2022) Upinder Kaur; Sapna Bala; Aditi Joshi; Noti Taruni Srija Reddy; Chetan Japur; Mayank Chauhan; Nikitha Pedapanga; Shubham Kumar; Anurup Mukherjee; Vaibhav Mishra; Dolly Talda; Rohit Singh; Rohit Kumar Gupta; Ashish Kumar Yadav; Poonam Jyoti Rana; Jyoti Srivastava; Shobha Bhat K; Anup Singh; G. Naveen Kumar P.; Manoj Pandey; Kishor Patwardhan; Sangeeta Kansal; Sankha Shubhra Chakrabarti
Background There is paucity of real-world data on COVID-19 vaccine effectiveness from cohort designs. Variable vaccine performance has been observed in test-negative case-control designs. There is also scarce real-world data of health issues in individuals receiving vaccines after prior COVID-19, and of adverse events of significant concern (AESCs) in the vaccinated. Methods: A cohort study was conducted from July 2021 to December 2021 in a tertiary hospital of North India. The primary outcome was vaccine effectiveness against COVID-19 during the second wave in India. Secondary outcomes were AESCs, and persistent health issues in those receiving COVID-19 vaccines. Regression analyses were performed to determine risk factors of COVID-19 outcomes and persistent health issues. Results: Of the 2760 health care workers included, 2544 had received COVID-19 vaccines, with COVISHIELD (rChAdOx1-nCoV-19 vaccine) received by 2476 (97.3%) and COVAXIN (inactivated SARS-CoV-2 vaccine) by 64 (2.5%). A total of 2691 HCWs were included in the vaccine effectiveness analysis, and 973 COVID-19 events were reported during the period of analysis. Maximum effectiveness of two doses of vaccine in preventing COVID-19 occurrence was 17% across three different strategies of analysis adopted for robustness of data. One-dose recipients were at 1.27-times increased risk of COVID-19. Prior SARS-CoV-2 infection was a strong independent protective factor against COVID-19 (aOR 0.66). Full vaccination reduced moderate–severe COVID-19 by 57%. Those with lung disease were at 2.54-times increased risk of moderate–severe COVID-19, independent of vaccination status. AESCs were observed in 33/2544 (1.3%) vaccinees, including one case each of myocarditis and severe hypersensitivity. Individuals with hypothyroidism were at 5-times higher risk and those receiving a vaccine after recovery from COVID-19 were at 3-times higher risk of persistent health issues. Conclusions: COVID-19 vaccination reduced COVID-19 severity but offered marginal protection against occurrence. The possible relationship of asthma and hypothyroidism with COVID-19 outcomes necessitates focused research. With independent protection of SARS-CoV-2 infection, and high-risk of persistent health issues in individuals receiving vaccine after recovery from SARS-CoV-2 infection, the recommendation of vaccinating those with prior SARS-CoV-2 infection needs reconsideration. © 2022 by the authors.
Thermal transport and optical anisotropy in CVD grown large area few-layer MoS2 over an FTO substrate
(American Institute of Physics Inc., 2024) Ankita Singh; Rohit Kumar Gupta; Ashish Kumar Mishra
Atomically thin MoS2 is a promising candidate for its integration into devices due to its strikingly unique electronic, optical, and thermal properties. Here, we report the fabrication of a few-layer MoS2 thin film over a conducting fluorine-doped tin oxide-coated glass substrate via a one-step chemical vapor deposition method. We have quantitatively analyzed the nonlinear temperature-dependent Raman shift using a physical model that includes thermal expansion and three- and four-phonon anharmonic effects, which exhibits that the main origin of nonlinearity in both the phonon modes primarily arises from the three-phonon anharmonic process. We have also measured the interfacial thermal conductance (g) and thermal conductivity (ks) of the synthesized film using the optothermal Raman spectroscopy technique. The obtained values of g and ks are ∼7.218 ± 0.023 MW m−2 K−1 and ∼40 ± 2 W m−1 K−1, respectively, suggesting the suitability of thermal dissipation in MoS2 based electronic and optoelectronic devices. Furthermore, we performed a polarization study using the angle resolved polarized Raman spectroscopy technique under non-resonance and resonance excitations to reveal the electron-photon-phonon interaction in the prepared MoS2, based on the semi-classical theory that includes deformation potential and Fröhlich interaction. Our study provides much needed experimental information about thermal conductivity and polarization response in a few-layer MoS2 grown over the conducting substrate, which is relevant for applications in low power thermoelectric and optoelectronic devices. © 2024 Author(s).