Publications by authors named "S Narendranath"

5 Publications

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Bio-corrosion impacts on mechanical integrity of ZM21 Mg for orthopaedic implant application processed by equal channel angular pressing.

J Mater Sci Mater Med 2021 Jun 12;32(6):65. Epub 2021 Jun 12.

Yenepoya Research Centre, Yenepoya Medical College, Yenepoya (Deemed to be University), Deralakatte, Mangalore, Karnataka, India.

The mechanical integrity of rolled ZM21 Mg was improved by equal channel angular pressing (ECAP) to function as a potential biodegradable bone screw implant. Electron backscattered diffraction (EBSD) revealed deformed grains of 45 µm observed in rolled ZM21 Mg. They were transformed to equiaxed fine grains of 5.4 µm after 4 pass ECAP. The yield strength of rolled and ECAPed ZM21 Mg alloys were comparable. In contrast, 4 pass ZM21 Mg exhibited relatively higher elongation when compared to rolled sample. The mechanical properties of rolled and ECAPed ZM21 Mg were dependant on both grain refinement and crystallographic texture. The rolled and 4 pass ECAPed tensile samples exhibited nonlinear deterioration of mechanical properties when tested after 7, 14, 21 and 28 days immersion in Hank's solution. The evaluation signifies that regardless their processing condition, ZM21 Mg alloys are suitable for surgical areas that requires high mechanical strength. In addition, the 4 pass ECAP samples were viable to MG-63 cells proving themselves to be promising candidates for future in vivo studies.
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http://dx.doi.org/10.1007/s10856-021-06535-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8197699PMC
June 2021

Visible light-driven photocatalytic degradation of methylene blue dye over bismuth-doped cerium oxide mesoporous nanoparticles.

Environ Sci Pollut Res Int 2021 Jan 15;28(4):4147-4155. Epub 2020 Sep 15.

Department of Chemistry, University of Calicut, Kerala, 673 635, India.

A series of Bi-doped ceria nanoparticles (0 to 20 wt% of Bi) were synthesized by sol-gel assisted hydrothermal method at a lower temperature of 150 °C. The synthesized nanoparticles were found to be effective photocatalysts for the degradation of methylene blue dye under visible light irradiation. The synthesized photocatalysts were well characterized by crystallographic, microscopic and spectroscopic methods. XRD patterns showed that the developed photocatalysts have cubic fluorite structure, and the absence of any impurity peaks in the XRD patterns of doped samples emphasizes the effective doping in host lattice. All samples exhibited mesoporous nature as evident from the adsorption and desorption pore size measurement. The shift of band gap energy from UV to visible region (2.90-2.77 eV) of the undoped and doped ceria results in the photo degradation of methylene blue dye in the visible light.
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http://dx.doi.org/10.1007/s11356-020-10750-yDOI Listing
January 2021

Photocatalytic H2 evolution from water-methanol system by anisotropic InFeO3(ZnO)(m) oxides without cocatalyst in visible light.

ACS Appl Mater Interfaces 2014 Aug 17;6(15):12321-7. Epub 2014 Jul 17.

Catalysis Division, CSIR-National Chemical Laboratory , Dr. Homi Bhabha Road, Pune 411008, India.

InFeO3(ZnO)m series of oxides are found to give unprecedented H2 evolution from water-methanol mixtures without using any cocatalysts. This family of compounds has an anisotropically layered structure in which Zn/FeOn polyhedra are sandwiched between InO6 octahedral layers. Local structure characterization by X-ray absorption spectroscopy reveals that Zn coordination changes from pentacoordinated to tetrahedral geometry across the series, whereas Fe geometry remains trigonal bipyramidal in all the compounds. This peculiar structure is conducive for a spatial separation of photogenerated charges reducing recombination losses. Band gap energies calculated from absorption spectra indicate potential visible light activity, and this may be due to the orbital mixing of Fe 3d and O 2p as revealed by pre-edge features of X-ray absorption spectra. Band positions are also advantageously placed for a visible light H2 generation and is indeed found to be the case in methanol-assisted water splitting with standardized hydrogen evolution of ∼19.5 mmol g(-1) h(-1) for all the catalysts.
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http://dx.doi.org/10.1021/am501976zDOI Listing
August 2014

Investigations into variations in local cationic environment in layered oxide series InGaO3(ZnO)m (m = 1-4).

Dalton Trans 2014 Feb;43(5):2120-6

Catalysis and Inorganic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India.

Layered oxides of the series InGaO3(ZnO)m (m = 1-4) are interesting due to their structural anisotropy. Here, we report a comprehensive study of their structural details, focusing on the local cationic environment in bulk powder samples by MASNMR and EXAFS, which is hitherto not attempted. It is found that the Ga geometry varies gradually from pure pentacoordinated to a mixture of penta and tetracoordinated with increasing amounts of tetracoordination as we move across the series, contrary to previous reports suggesting exclusively trigonal bipyramidal coordination in all the compounds. A similar observation is also made in the case of Zn and structural evolution involving the dissolution of Ga in a ZnO4 tetrahedral network in a sandwich layer can be discerned, as the insulating ZnO layer size increases.
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http://dx.doi.org/10.1039/c3dt52011kDOI Listing
February 2014
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