S. V. Santhana Mariappan

Indian Institute of Technology Ropar, Rūpar, Punjab, India

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Publications (3)4.75 Total impact

  • S. V. Santhana Mariappan · L. Gomathi · S. Subramanian
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    ABSTRACT: The structural changes during the complexation of benzo-crown ethers with Cs+, K+ and Na+ were studied by NOESY and variable-temperature 13C NMR spectroscopy. It was found that, on complexation, the distance between the CH-α and 1-CH2 is reduced in dibenzo-24-crown-8 (DB24C8), dibenzo-18-crown-6 and benzo-15-crown-5. Two mechanisms have been proposed for the distance reduction, the fluttering motion of the benzo group and the elongation of the crown moiety. However, it is concluded that both of these mechanisms seem to play a role in the distance reduction. In the complexed state of DB24C8 with Cs+, Cs+ is predicted to be slightly above the plane of the crown oxygens with respect to DB24C8.
    No preview · Article · Jul 1991 · Magnetic Resonance in Chemistry
  • S. V. Santhana Mariappan · S Subramanian · N Chandrakumar · K R Rajalakshmi · S S Sukumaran
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    ABSTRACT: Proton nuclear magnetic resonance relaxation parameters (T1, T2) were measured for over 100 malignant and normal tissue samples of various organs of the human body. The purpose of this study was to estimate the reliability of the NMR technique in discriminating normal from malignant tissues. Breast and cervix samples were analyzed by using the malignancy index concept and we were able to distinguish malignant and normal tissue in 17 out of 18 breast samples and 5 out of 7 cervix samples. Since the relaxation data of a normal control population of the other organs were not available, the data for these are reported without any further analysis. The distinction between carcinomas and sarcomas was also made by using the estimated relaxation parameters. Malignancy indices of breast tissue samples for linear least-squares and nonlinear two-parameter and three-parameter least-squares procedures were calculated and used to evaluate the relative efficiencies in discriminating malignant from normal tissues.
    No preview · Article · Oct 1988 · Magnetic Resonance in Medicine
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    S. V. Santhana Mariappan · S. Subramanian
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    ABSTRACT: extreme narrowing, intermediate and spin diffusion limits interms of the value of the product of the spectrometer frequency and isotropic rotational molecular tumbling correlation time ( JC CY. Various methods have been proposed to extract internuclear distances of the dipolar network from NOESY and ROESY intensities, which depend upon ^ Q , mixing time C^,,)* and T along with the distances. Since the aependence is multidimensional and spin diffusion creates serious problems with respect to bigger molecules, the optimization of t for a particular spectrometer frequency is necessary in order to derive internuclear
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