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College of Science, India

Master R.,UGC-DAE Consortium for Scientific Research | Tiwari S.,UGC-DAE Consortium for Scientific Research | Tiwari S.,Mls University | Choudhary R.J.,UGC-DAE Consortium for Scientific Research | And 3 more authors.
Journal of Applied Physics | Year: 2011

We present low-temperature infrared measurements of magnetite (Fe 3O 4) thin films on Si (111) substrate across the Verwey transition temperature (T V). The line parameters of the most intense t 1u mode observed in the Fourier transform infra red spectrum of the film is studied as a function of temperature. We observe that mode frequency increases abruptly at 130 K, and full width at half maxima of the mode increases abruptly at 113 K. The observations point out that structural transition may start earlier at 130 K than the actual Verwey transition (121 K) and that complete at 113 K. These results are consistent with the higher transition temperature as observed in resistivity and magnetization measurements. © 2011 American Institute of Physics. Source

de Wall H.,Friedrich - Alexander - University, Erlangen - Nuremberg | Pandit M.K.,University of Rajasthan | Chauhan N.K.,Mls University
Precambrian Research | Year: 2012

The Archean-Proterozoic contact (APC) comprises a large scale folded surface around Udaipur in NW India. The APC is exposed on both eastern and western flanks of a synclinorium formed during thick skinned thrusting of the Archean basement and the Paleoproterozoic cover units. Paleosol occurrences on both the limbs of this structure imply an originally continuous paleoweathering horizon and not individual pockets of paleosol as seen today. Preservation of paleosol sections along the Archean-Proterozoic interface in the Aravalli craton is strongly controlled by the structural grain. Complete paleosol sections are recognized in the eastern flank of the Udaipur synclinorium in low strain regions with respect to the regional F1 and F2 folding. In this sector the Tulsi Namla paleosol section represents an ancient lateritic weathering profile with an iron depleted pallid lower zone (lithomarge) and an iron enriched upper zone (mottled zone to ferricrete). Original kaolinite in the saprolite and pallid zone has been transformed into kyanite during metamorphism and subsequently to white mica during retrograde overprint, while Fe rich clay and goethite were probably the primary minerals for the chloritoid and hematite which now constitute the upper zone. At the western flank of the synclinorium the contact is heavily sheared and Archean basement and Proterozoic units show interfingering on a small scale. Here, the paleosol sections are incomplete.The weathering interval can be inferred by the stabilization of the craton at ~2.5. Ga and deposition of rift related sequences of the Aravalli basin (Delwara formation) at ~2.15 Ga. The Udaipur paleosols, especially in the eastern flank, represent the most complete Archean-Paleoproterozoic paleosol sections in India. © 2012 Elsevier B.V. Source

Galav P.,Mls University | Dashora N.,National Atmospheric Research Laboratory | Sharma S.,Mls University | Pandey R.,Mls University
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2010

We present the mean diurnal, seasonal and annual variations in TEC during the lowest solar activity phase from low latitude Indian zone recorded at Udaipur (Geog. Lat. 24.6°N, Geog. Long.73.7°E, Geomag. Lat. 15.6°N) using a GPS receiver. Seasonal variations in daytime TEC show a semiannual periodicity, with a minimum in winter. Results of seasonal variations have been compared with that of the IRI-2007 model. Model calculations reveal significant seasonal as well as longitudinal differences in TEC. Seasonal variations in the nighttime TEC reveal an annual periodicity. Near the crest of the EIA, TEC shows a very good correlation with the solar flux. The results also point to weakening of the anomaly crest as well as its spatial and temporal contraction with declining solar activity. © 2010 Elsevier Ltd. Source

Sharma S.,Mls University | Dashora N.,National Atmospheric Research Laboratory | Galav P.,Mls University | Pandey R.,Mls University
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2010

The longest total solar eclipse during the 21st century occurred in South and East Asia on July 22, 2009. Ionospheric response to this rare total solar eclipse which was observed right from the time of sunrise in the Indian zone, has been studied in terms of the total electron content (TEC) obtained from three global positioning system (GPS) receivers located at Udaipur, Hyderabad and Bengaluru, and electron density obtained using space based GPS-Radio Occultation technique. The study reveals significant reductions in the electron density and TEC that persisted up to 2. h past the last contact even during early morning eclipse. These observations imply that during the early morning eclipse, the production and loss of ionization dominate over the plasma transport processes. © 2010 Elsevier Ltd. Source

Cadmium, is a highly toxic heavy metal, and is a known carcinogen, clastogen and a mutagen and it poses severe risk to human health. Humans are exposed to cadmium via variable modes i.e. through food and drinking water, by inhalation, cigarette smoking etc. It serves no physiological function within mammalian system. ATSDR (The Agency for Toxic Substances and Disease Registry) has listed cadmium as number 7 in its top 20 list of hazardous substances and International Agency for Research on Cancer (IARC) has classified cadmium as a group 1 carcinogen. In contrast to the activity of cadmium, curcumin the yellow coloured polyphenolic super antioxidant derived from powdered rhizome of Curcuma longa is useful in various debilitating conditions. It is also recommended in cancer prevention and as a treatment adjunct in various diseases. Hence, the aim of the present experimental design was to assess the protective effect of curcumin on cadmium chloride induced genotoxicity in bone marrow chromosomes of Swiss albino mice. In the present experiment four batches of Swiss-albino mice were maintained. The experimental group was administered only single oral dose of cadmium chloride (50mg/kg/animal/day). The subsequent experimental group was administered curcumin (10mg/animal/day) for 15 days and on the 16th day cadmium chloride (50mg/kg/animal/day) was administered. For each experimental group a parallel control group was maintained. Two days after the administration of the last dose, mice were sacrificed and air-dried metaphase preparations were made and subsequently assessed for chromosomal damage. In animals treated with only cadmium chloride there was a significant decline in mitotic index. The aneugenic property of cadmium chloride was distinctly discernible, besides other chromosomal aberrations such as polyploidy terminal deletions and breaks were also observed. In comparison an elevation in mitotic index equivalent to normal group was discerned in animals pre-treated with curcumin and subsequently treated with cadmium chloride and an overall decline in the mutation rate was also discernible clearly indicating the protective effect of curcumin. Source

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