Browsing by Author "Kumar A."

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Comparative cyto- and genotoxicity of 900 MHz and 1800 MHz electromagnetic field radiations in root meristems of Allium cepa
(Academic Press, 2020) Kumar A.; Kaur S.; Chandel S.; Singh H.P.; Batish D.R.; Kohli R.K.
In the last few decades, tremendous increase in the use of wireless electronic gadgets, particularly the cell phones, has significantly enhanced the levels of electromagnetic field radiations (EMF-r) in the environment. Therefore, it is pertinent to study the effect of these radiations on biological systems including plants. We investigated comparative cytotoxic and DNA damaging effects of 900 and 1800 MHz EMF-r in Allium cepa (onion) root meristematic cells in terms of mitotic index (MI), chromosomal aberrations (CAs) and single cell gel electrophoresis (comet assay). Onion bulbs were subjected to 900 and 1800 MHz (at power densities 261 ± 8.50 mW m?2 and 332 ± 10.36 mW m?2, respectively) of EMF-r for 0.5 h, 1 h, 2 h, and 4 h. Root length declined by 13.2% and 12.3%, whereas root thickness was increased by 46.7% and 48.3% after 4 h exposure to 900 MHz and 1800 MHz, respectively. Cytogenetic studies exhibited clastogenic effect of EMF-r as depicted by increased CAs and MI. MI increased by 36% and 53% after 2 and 4 h exposure to 900 MHz EMF-r, whereas it increased by 41% and 67% in response to 1800 MHz EMF-r. Aberration index was increased by 41%–266% and 14%–257% during 0.5–4 h of exposure to 900 MHz and 1800 MHz, respectively, over the control. EMF-r exposure decreased % head DNA (DNAH) and increased % tail DNA (DNAT) and olive tail moment (OTM) at both 900 and 1800 EMF-r. In 4 h exposure treatments, head DNA (%) declined by 19% and 23% at 900 MHz and 1800 MHz, respectively. DNAT and OTM were increased by 2.3 and 3.7 fold upon exposure to 900 MHz EMF-r over that in the control, whereas 2.8 and 5.8 fold increase was observed in response to 1800 MHz EMF-r exposure for 4 h and the difference was statistically significant. The study concludes that EMF-r in the communication range (900 and 1800 MHz) adversely affect root meristems in plants and induce cytotoxic and DNA damage. EMF-r induced DNA damage was more pronounced at 1800 MHz than that at 900 MHz.
Electron transport and thermoelectric performance of defected monolayer MoS2
(Elsevier B.V., 2019) Sharma M.; Kumar A.; Ahluwalia P.K.
Electronic and thermoelectric properties of a two-dimensional MoS2 monolayer containing atomic defects are investigated using density functional theory. All the atomic defects have been found to exhibit endothermic nature. Electronic structure of MoS2 shows tuneability of band gap with the atomic defects. The MoS2 vacancy in pristine monolayer makes it magnetic and narrow band gap semiconductor. The spin-polarized character of the monolayer with defects is clearly captured by the tunneling current calculated in the STM-like setup. A relatively low thermal conductivity has been observed in monolayers with defects as compared to pristine form resulting in enhanced room temperature figure of merit as high as 6.24 and 1.30 respectively. The results presented open up a new window for the use of monolayer MoS2 in electronic devices, thermal management and thermoelectric devices.
Fake news detection of Indian and United States election data using machine learning algorithm
(Blue Eyes Intelligence Engineering and Sciences Publication, 2019) Kumar A.; Singh S.; Kaur G.
The world of digital media is thriving by the day and hence, there is an urge of businesses to magnify it more gaining them maximum financial benefits. This particular urge calls for more and more expansions concerning creating and developing new content whether it's in the form of websites that aims at branding businesses or could be in the form of online newspapers and magazines. Since from last few decades’ medium of communication had changed. Now a day people are using social networks very extensively for news updates. These networks aim to make social lives better. Today, everyone knows and uses social media which contains unverified article, post, message and news. Nowadays' fake news is making various issues from mocking articles to a created news and plan government publicity in certain outlets. Fake news and the absence of trust in the media are developing issues with immense consequences in our general public. It is needed to look into how the techniques in the fields of computer science using machine learning, natural language processing helps us to detect fake news. Fake news is now observed as one of the major threats to freedom of expression, journalism, and democracy of a country. In this research, a comprehensive way of detecting fake news using machine learning model has been presented that is trained by Fake News data based on US election and trained on recent Indian political Fake news.
Pressure and electric field tuning of Schottky contacts in PdSe2/ZT-MoSe2 van der Waals heterostructure
(NLM (Medline), 2020) Jakhar M.; Singh J.; Kumar A.; Tankeshwar K.
A two-dimensional van der Waals (vdW) heterostructure (PdSe2/ZT-MoSe2) has been investigated through vdW corrected density functional theory. ZT-MoSe2 acts as a Dirac material with an anisotropic Dirac cone and variable Fermi velocity (0.52-1.91×נ105 ms-1). The intrinsic Schottky barrier height can be effectively tuned by applying external pressure and an electric field to the heterostructure. The p-type Schottky barrier transforms into a p-type ohmic contact at pressure P≈16 GPa. A positive electric field induces p-type ohmic contact while a negative electric field results in the transition from p-type Schottky contact to n-type Schottky contact, and finally to n-type ohmic contact at the higher values of the field. Moreover, the external positive (negative) electric field induces n-type (p-type) doping of ZT-MoSe2 in the heterostructure and remarkably controls the charge carrier concentration. Our results demonstrate that controlling the external pressure and electric field in a PdSe2/ZT-MoSe2 heterostructure can result in an unprecedented opportunity for the design of high-performance nanodevices.
Superior Mechanical and Electronic Properties of Novel 2D Allotropes of As and Sb Monolayers
(American Chemical Society, 2019) Jamdagni P.; Thakur A.; Kumar A.; Ahluwalia P.K.; Pandey R.
Novel monolayer allotropes of As and Sb monolayers are predicted to be energetically and dynamically stable by calculations based on density functional theory. Remarkably, these monolayers possess superior mechanical flexibility and can withstand tensile strain as large as 58% in the armchair direction and 24% in the zigzag direction, which are higher than the strain limits of 2D materials such as graphene, MoS2, and phosphorene. The predicted mechanical flexibility is mainly due to the highly puckered nature of these monolayer structures. Tensile strain along the armchair direction expands the puckering of the structure by increasing the dihedral angle without a significant increase in the bond lengths. Moreover, the mechanical properties are found to be highly anisotropic: Young's modulus in the armchair direction is 3 times less than that in the zigzag direction. Furthermore, we show that these monolayer allotropes undergo semiconductor-to-metal transition on application of uniaxial strains and a transverse electric field. The calculated results show the possibility of wide-range tuning of the band gap of these monolayers while keeping their direct gap behavior intact, which can be useful in optoelectronic applications including light-emitting diodes and solar cells.