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148 results on '"Kutty, P R"'

3. Synthesis of Nanoparticles of the Giant Dielectric Material, CaCu3Ti4O12 from a Precursor Route

Author

Thomas, P., Dwarakanath, K., Varma, K. B. R., and Kutty, T. R. N.

Subjects
Condensed Matter - Materials Science
Abstract

A complex oxalate precursor, CaCu3(TiO)4(C2O4)8.9H2O, was synthesized and the precipitate that obtained was confirmed to be monophasic by the wet chemical analyses, X-ray diffraction, FTIR absorption and TG, DTA analyses. The thermal decomposition of this oxalate precursor led to the formation of phase-pure calcium copper titanate, CaCu3Ti4O12, at 680oC. The bright field TEM micrographs revealed that the size of the as synthesized crystallites to be in the 30 to 80 nm range. The powders so obtained had excellent sinterability resulting in high density ceramics which exhibited giant dielectric constants upto 40000 (1 kHz) at 25oC accompanied by low dielectric losses, less than 0.07., Comment: arXiv admin note: substantial text overlap with arXiv:1301.4064

Published
2013

4. Nanoparticles of the giant dielectric material, CaCu3Ti4O12 from a precursor route

Author

Thomas, P., Dwarakanath, K., Varma, K. B. R., and Kutty, T. R. N.

Subjects
Condensed Matter - Materials Science
Abstract

A method of preparing the nanoparticles of CaCu3Ti4O12 (CCTO) with the crystallite size varying from 30 to 200 nm is optimized at a temperature as low as 680 1C from the exothermic thermal decomposition of an oxalate precursor, CaCu3(TiO)4(C2O4)8 ? 9H2O. The phase singularity of the complex oxalate precursor is confirmed by the wet chemical analyses, X-ray diffraction, FT-IR and TGA,DTA analyses. The UV Vis reflectance and ESR spectra of CCTO powders indicate that the Cu(II) coordination changes from distorted octahedra to nearly flattened tetrahedra (squashed) to square-planar geometry with increasing annealing temperature. The HRTEM images have revealed that the evolution of the microstructure in nanoscale is related to the change in Cu(II) coordination around the surface regions for the chemically prepared powder specimens. The nearly flattened tetrahedral geometry prevails for CuO4 in the near surface regions of the particles, whereas square-planar CuO4 groups are dominant in the interior regions of the nanoparticles. The powders derived from the oxalate precursor have excellent sinterability, resulting in high-density ceramics which exhibited giant dielectric constants upto 40,000 (1 kHz) at 25 1C, accompanied by low dielectric loss 0.07.

Published
2013
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8. Effectiveness of an oral health education intervention among 6-12-year-old children: A cluster randomized controlled trial.

Author

Suresh, Neethu, Kutty, V. R., Kumar, K. N., Sarma, P. S., Vijayan, Aravind A., Aljuaid, Mohammed, Shahid, Duaa, and Thankappan, Kavumpurathu R.

Abstract

Objectives: Literature on the effectiveness of theory-based oral health education on the oral hygiene of children is limited. We aimed to determine the effectiveness of an health behaviour theory-based school oral health education intervention on 1) oral hygiene and 2) oral health-related knowledge, attitude and practices among 6-12-year-old children in Kerala, India. Methods: Cluster randomized controlled trial. Sixteen class divisions (clusters) were randomized into intervention and control groups of 225 and 228 children respectively. Primary and secondary outcomes were plaque score as measured using the simplified oral hygiene index (OHI-S) and oral health-related knowledge, attitude and practices respectively. The intervention group received structured oral health education classes for three months and materials including pamphlets. Children in the control group were not given the classes or materials. Results: Post-intervention OHI-S scores in the intervention group and control groups were 1.65 and 2.17 respectively (difference = -0.52, 95%CI -0.86, -0.18). All the secondary outcomes improved in the intervention group compared to the control group. Conclusions: The intervention improved the oral hygiene status, oral health-related knowledge, attitude and practices of the children. Longer term follow-up and economic appraisal are needed to help policymakers plan and develop OHEI based on health behaviour theories. [ABSTRACT FROM AUTHOR]

Published
2023
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