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Sehgal S.,Electronics and Communication Engineering | Singh H.,SSPL | Agarwal M.,University of Delhi | Bhasker V.,Electronics and Communication Engineering | Shantanu,Electronics and Communication Engineering
2014 International Conference on Medical Imaging, m-Health and Emerging Communication Systems, MedCom 2014

In this paper, we have evaluated an algorithm using Principal Component Analysis (PCA) for its application in data analysis. In the research field, it is very difficult to understand the large amount of data and is very time consuming too. Therefore, in order to avoid wastage of time and for the ease in understanding we have scrutinized a PCA algorithm that can reduce the huge dimension of the data into 2-dimensional. The method of PCA is used to compress the maximum amount of information into first two columns of the transformed matrix known as the principal components by neglecting the other vectors that carries the negligible information or redundant data. The main objective of the paper is to separate two compounds say A and B having different concentrations for all four sensors and identifies which sensors have the similar or different concentration with the help of various plots that explains the correlation between the different variables. © 2014 IEEE. Source

Gautam P.,University of Delhi | Sachdeva A.,University of Delhi | Singh S.K.,SSPL | Tandon R.P.,University of Delhi
Journal of Alloys and Compounds

Single phase polycrystalline Mn-modified Bi3.25La 0.75Ti3O12 (BLT) thin films were prepared by chemical solution deposition method using spin coating technique on Pt/Ti/SiO2/Si (1 0 0) substrates. Raman spectroscopy of these films shows that Mn3+ is well substituted at Ti4+ site. The optical properties of BLT and Mn modified BLT thin films were investigated at room temperature by using spectroscopic ellipsometry (SE) in the energy range 0.72-6.2 eV. A double Tauc-Lorentz (DTL) dispersion relation was successfully used to model the dielectric functions of these films where a shift to the lower energy side with Mn doping is seen. The full width at half maxima (FWHM) (Cyrillic capital letter GHE) of dielectric function is found to increase with Mn doping. This increase in FWHM may be attributed to the increase in the trap density in forbidden band which consequently decreases the value of direct optical band gap (Egd). The direct optical band gap (Egd) is found to decrease with increase in Mn content in the studied composition range. This decrease in Egd with doping may be attributed to the variation in the defect concentration present in the structure. © 2014 Elsevier B.V. All rights reserved.. Source

Gautam P.,University of Delhi | Singh S.K.,SSPL | Tandon R.P.,University of Delhi
Journal of Alloys and Compounds

Bi3.25La0.75Ti3O12 (BLT) is one of the prospective candidate materials for data storage devices application. In order to understand the leakage current conduction mechanism in BLT we have studied Mn doped Bi3.25La0.75Ti3O12 (BLT) thin films with varying concentration of Mn. These films were prepared by chemical solution deposition technique. The structure and phase analysis of these films was performed at room temperature by X-ray diffraction, and scanning electron microscope was used to investigate the surface morphology. Different leakage current conduction mechanisms, e.g., Schottky emission, Modified Schottky, Poole-Frenkel emission and space charge limited (Lampert's theory) conduction were examined to explain the true nature of charge transport phenomena in BLT and Mn doped BLT thin films. It was found that BLT and Mn doped BLT thin films leakage current conduction mechanism follows the Lampert's theory of space charge limited conduction in an insulator with traps. © 2014 Elsevier B.V. All rights reserved. Source

Rahman M.A.,Allahabad University | Soumya K.K.,Allahabad University | Tripathi A.,Allahabad University | Sundaram S.,Allahabad University | And 2 more authors.
Toxicological and Environmental Chemistry

This study attempted to determine the effects of heavy metals on the photosynthetic blue-green algae for their potential to use as a biosensor. The bioaccumulation of metals and its effects on pigments of Nostoc muscorum and Synechococcus PCC 7942 were assessed. The culture was grown in BG 11 liquid medium supplied with different metals like mercury (Hg), lead (Pb), and cadmium (Cd) and incubated (μM 20 concentrations) for 10 days under optimal conditions. The accumulated amounts of metals were determined by atomic absorption spectroscopy (AAS). The stress effects on photosynthetic pigment chlorophyll a (Chl a) were monitored by laser-induced fluorescence (LIF). Bio-concentration factor (BCF) reached a peak in cells on the 2nd day of incubation followed by a gradual reduction. The highest reduction in the pigment concentrations (Chl a and β carotene) was observed at 20 μM L -1 Hg treatment. The results indicate that, cyanobacteria may serve as both potential species to be used as a biosensor and used to clean up heavy metals from contaminated water. These changes were analyzed with the long-term goal of exploiting cyanobacterial cells as biosensors. © 2011 Copyright Taylor and Francis Group, LLC. Source

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