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K. Sandeep,R. S. Negi,A. S. Panicker,Alok Sagar Gautam,D. S. Bhist,G. Beig,B. S. Murthy,R. Latha,Santosh Singh,S. Das 한국기상학회 2020 Asia-Pacific Journal of Atmospheric Sciences Vol.56 No.3
Extraction of organic carbon (OC) and elemental carbon (EC) were carried out over Srinagar, India, an ecologically sensitive semi-urban site in Garhwal Himalays. The PM2.5 sampling was carried out during January to December, 2017 over the site. The OC and EC were extracted from PM2.5 samples using a thermo optical OC/EC analyzer. Highest OC and EC concncentrations were found during postmonsoon (17.67 ± 1.1 μg/m3 OC and 6.34 ± 0.75 EC) and Winter (17.31 ± 3.045 μg/m3 OC and 6.32 ± 0.585 μg/m3 EC) seasons are attributed to boundary layer dynamics and anthropogenic activities. The lower concentration of OC/ EC was observed during monsoon season (11.64 ± 1.75 μgm−3 OC and 3.46 ± 0.19μgm−3 EC) owing to wet scavenging of aerosols and minimum count of forest fire/biomass buring incidences. Both pre-monsoon and post-monsoon season concentrations are also influenced by biomass burning in the IGP (Indo-Gangetic Plain) region and forest fires in the adjecent areas. The OC/EC ratio sounds that vehicular exhaust and biomass burning are the major source of OC/EC over the site. Generation of secondary organic carbon (SOC) at the region causes variability in OC/EC ratio in different seasons. It is found that 24–32% of PM2.5 is contributed by carbonaceous aerosols (OC and EC) over Srinagar. The pivotal role of meteorology in modulating OC/ EC concentrations has been illustared in detail.
Consequences of electronic excitations in CoFe<sub>1.90</sub>Dy<sub>0.10</sub>O<sub>4</sub>
Kumar, H.,Singh, J.P.,Srivastava, R.C.,Negi, P.,Agrawal, H.M.,Asokan, K.,Won, S.O.,Chae, K.H. Elsevier 2015 CURRENT APPLIED PHYSICS Vol.15 No.12
Present work reports the irradiation induced effects in Dy<SUP>3+</SUP> doped cobalt ferrite nanoparticles in the regime of dominant electronic excitation processes induced by 100 MeV O<SUP>7+</SUP> ion irradiation. Irradiation leads to the deterioration of crystalline phase as envisaged by X-ray diffraction. Crystallite size decreases with the increase of irradiation fluence. Disappearance of certain bands in Raman spectra at higher fluence of irradiation confirms the crystalline disorder induced by electronic excitations. Fourier transform infrared spectra show onset of cation migration from tetrahedral site to octahedral site and vice versa. X-ray absorption fine structure measurements depict the preservation of valence state of metal ions after irradiation. These measurements further infer bond breaking process in irradiated materials. Magnetic measurements carried out on these materials indicate slight increase of saturation magnetization at room temperature followed by the decrease of coercive field. Obtained results are discussed on the basis of appropriate mechanism.