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Polley CM, Fedderwitz H, Balasubramanian T, Zakharov AA, Yakimova R, Bäcke O, Ekman J, Dash SP, Kubatkin S, Lara-Avila S. Bottom-Up Growth of Monolayer Honeycomb SiC. Phys Rev Lett 2023; 130:076203. [PMID: 36867809 DOI: 10.1103/physrevlett.130.076203] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 12/22/2022] [Indexed: 06/18/2023]
Abstract
The long theorized two-dimensional allotrope of SiC has remained elusive amid the exploration of graphenelike honeycomb structured monolayers. It is anticipated to possess a large direct band gap (2.5 eV), ambient stability, and chemical versatility. While sp^{2} bonding between silicon and carbon is energetically favorable, only disordered nanoflakes have been reported to date. Here we demonstrate large-area, bottom-up synthesis of monocrystalline, epitaxial monolayer honeycomb SiC atop ultrathin transition metal carbide films on SiC substrates. We find the 2D phase of SiC to be almost planar and stable at high temperatures, up to 1200 °C in vacuum. Interactions between the 2D-SiC and the transition metal carbide surface result in a Dirac-like feature in the electronic band structure, which in the case of a TaC substrate is strongly spin-split. Our findings represent the first step towards routine and tailored synthesis of 2D-SiC monolayers, and this novel heteroepitaxial system may find diverse applications ranging from photovoltaics to topological superconductivity.
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Affiliation(s)
- C M Polley
- MAX IV Laboratory, Lund University, Fotongatan 2, 22484 Lund, Sweden
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - H Fedderwitz
- MAX IV Laboratory, Lund University, Fotongatan 2, 22484 Lund, Sweden
| | - T Balasubramanian
- MAX IV Laboratory, Lund University, Fotongatan 2, 22484 Lund, Sweden
| | - A A Zakharov
- MAX IV Laboratory, Lund University, Fotongatan 2, 22484 Lund, Sweden
| | - R Yakimova
- Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, 581 83 Sweden
| | - O Bäcke
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - J Ekman
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - S P Dash
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - S Kubatkin
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - S Lara-Avila
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom
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Kuttippurath J, Singh A, Dash SP, Mallick N, Clerbaux C, Van Damme M, Clarisse L, Coheur PF, Raj S, Abbhishek K, Varikoden H. Record high levels of atmospheric ammonia over India: Spatial and temporal analyses. Sci Total Environ 2020; 740:139986. [PMID: 32927535 DOI: 10.1016/j.scitotenv.2020.139986] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 06/03/2020] [Accepted: 06/03/2020] [Indexed: 06/11/2023]
Abstract
Atmospheric ammonia (NH3) is an alkaline gas and a prominent constituent of the nitrogen cycle that adversely affects ecosystems at higher concentrations. It is a pollutant, which influences all three spheres such as haze formation in the atmosphere, soil acidification in the lithosphere, and eutrophication in water bodies. Atmospheric NH3 reacts with sulfur (SOx) and nitrogen (NOx) oxides to form aerosols, which eventually affect human health and climate. Here, we present the seasonal and inter-annual variability of atmospheric NH3 over India in 2008-2016 using the IASI (Infrared Atmospheric Sounding Interferometer) satellite observations. We find that Indo-Gangetic Plains (IGP) is one of the largest and rapidly growing NH3 hotspots of the world, with a growth rate of +1.2% yr-1 in summer (June-August: Kharif season), due to intense agricultural activities and presence of many fertilizer industries there. However, our analyses show insignificant decreasing trends in annual NH3 of about -0.8% yr-1 in all India, about -0.4% yr-1 in IGP, and -1.0% yr-1 in the rest of India. Ammonia is positively correlated with total fertilizer consumption (r = 0.75) and temperature (r = 0.5) since high temperature favors volatilization, and is anti-correlated with total precipitation (r = from -0.2, but -0.8 in the Rabi season: October-February) as wet deposition helps removal of atmospheric NH3. This study, henceforth, suggests the need for better fertilization practices and viable strategies to curb emissions, to alleviate the adverse health effects and negative impacts on the ecosystem in the region. On the other hand, the overall decreasing trend in atmospheric NH3 over India shows the positive actions, and commitment to the national missions and action plans to reduce atmospheric pollution and changes in climate.
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Affiliation(s)
- J Kuttippurath
- CORAL, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
| | - A Singh
- CORAL, Indian Institute of Technology Kharagpur, Kharagpur 721302, India; Agricultural and Food Engineering Department, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - S P Dash
- Department of Physics, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - N Mallick
- Agricultural and Food Engineering Department, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - C Clerbaux
- LATMOS/IPSL, Sorbonne Université, UVSQ, CNRS, Paris, France; Université libre de Bruxelles (ULB), Service de Chimie Quantique et Photophysique, Atmospheric Spectroscopy, Brussels, Belgium
| | - M Van Damme
- Université libre de Bruxelles (ULB), Service de Chimie Quantique et Photophysique, Atmospheric Spectroscopy, Brussels, Belgium
| | - L Clarisse
- Université libre de Bruxelles (ULB), Service de Chimie Quantique et Photophysique, Atmospheric Spectroscopy, Brussels, Belgium
| | - P-F Coheur
- Université libre de Bruxelles (ULB), Service de Chimie Quantique et Photophysique, Atmospheric Spectroscopy, Brussels, Belgium
| | - S Raj
- CORAL, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - K Abbhishek
- CORAL, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - H Varikoden
- ESSO-Indian Institute of Tropical Meteorology Pune, India
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Dash SP, Bourghawi SM, El-Amaari A. Randomization Analysis of Incomplete Data in Some Basic Designs. Biom J 1993. [DOI: 10.1002/bimj.4710350109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
One hundred and ninety-two patients with peripheral lymphadenopathy were screened and 80 patients with tubercular lymphadenitis were studied. Their ages ranged from 1 to 65 years; most were younger than 30 years and there was a slight female preponderance (1.2:1). Seventy per cent of patients were of low socioeconomic status. Of the 80 patients, 56 had affected cervical nodes, seven had inguinal nodes, five had axillary nodes and 12 had multiple sites of lymph node involvement. All had enlarged nodes which were matted in 44 cases and discrete in 18 cases, while the rest had either an abscess or a discharging sinus. Fifty-nine cases (74 per cent) showed a positive Mantoux test and four cases (5 per cent) had associated pulmonary tuberculosis. Fine needle aspiration cytology gave a positive diagnosis in 66 cases (83 per cent). Fifty-two cases showed a positive culture for Mycobacterium tuberculosis of human type in Lowenstein-Jensen medium. Short-term chemotherapy (9 months) consisting of rifampicin, isoniazid and ethambutol gave an excellent result. Surgery was not required in any of the cases.
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Affiliation(s)
- M C Dandapat
- Department of Surgery, M.K.C.G. Medical College, Orissa, India
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