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Author: search.filters.author.Edathazhe, A.B.Has files: No

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    Dissolution studies of Na2O-BaO-CaO-P2O5 glasses in deionized water under semi-dynamic conditions for bioactive applications
    (Elsevier Ltd, 2018) Edathazhe, A.B.; Shashikala, H.D.
    The phosphate glasses of composition Na2O-CaO-P2O5 are widely accepted glass material for biomedical applications. The glass samples with composition (26-x)Na2O-xBaO-29CaO-45P2O5 (x = 0,5,10,15) are prepared at 1100°C by melt-quenching technique. In order to reduce the fast dissolution rate, which limits their application, BaO is added by reducing Na2O composition. The dissolution studies have been carried out in deionized water under semi-dynamic conditions at 37°C for 14 days. The properties are studied based on Barium composition and time of immersion. The samples are taken out at 24 hrs. intervals to carry out weight loss and pH measurements. The rates of cation (Na+ and Ca2+) release from the glass to the solution were found out using flame photometer. The release of orthophosphate (PO43-) anions is measured by UV-Visible spectrometer using phospho-molybdenum blue method. The weight losses linearly increase with time for all the compositions. The addition of barium decreases the weight loss in deionized water. The pH of the solutions varies with dissolution of ions. The dissolution rate has been found out from the slope of the weight loss vs time graph and it decreased with increase in barium content. © 2018 Elsevier Ltd. All rights reserved.
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    Optical properties of BaO added bioactive Na2O-CaO-P2O5 glasses
    (American Institute of Physics Inc. subs@aip.org, 2018) Edathazhe, A.B.; Shashikala, H.D.
    This paper deals with the effect of BaO addition on the optical properties of bioactive Na2O-CaO-P2O5 glasses for biomedical optics applications. The phosphate glasses with composition (26-x)Na2O-xBaO-29CaO-45P2O5 (x = 0, 5, 10, 15 mol%) have been prepared by melt-quenching technique at 1100°C. The refractive index of glasses increased with BaO content. The optical band gap and Urbach energy of synthesized glasses were derived from the optical absorption spectra by using UV-Visible spectrometer. The addition of 5 mol% of BaO increased the band gap energy of glasses due to the formation of ionic cross-links in the glass structure. The defect and interstitial bonds formation in theglasses decreased with BaO additions as indicated by reductions in the Urbach energy values. No such variations in the band gap and Urbach energy values of glasses were observed with BaO content from 5 to 15 mol%. The molar and oxide ion polarizability values were calculated from the band gap and molar volume of glasses. The increase in the calculated optical basicity and metallization criteria of glasses supported the rise in band gap energy values with BaO additions. As the melting temperature of glasses decreased from 1200 to 1100°C, the refractive index increased as supported by the measured density values. The band gap energy is not changed with melting temperature. The Urbach energy decreased with decrease in melting temperature in case of BaO-free Na2O-CaO-P2O5 glasses, whereas it increased in case of BaO added glasses due to the role of BaO as modifying oxide. © 2018 Author(s).
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    Dissolution and in vitro bioactive properties of BaO added Na2O-CaO-P2O5 glasses
    (Society of Glass Technology christine@glass.demon.co.uk, 2018) Edathazhe, A.B.; Shashikala, H.D.
    Na2O-CaO-P2O5 glasses with different additions of BaO were subjected to dissolution tests in deionised water and in vitro bioactivity tests in phosphate buffer saline (PBS) as well as Hank's balanced salt (HBS) solution. Phosphate glasses of composition (26-x)Na2O-xBaO-29CaO-45P2O5 (x=0, 5, 10, 15 mol%) were prepared by melt-quenching. The dissolution characteristics of these glasses were studied in deionised water under static conditions based on BaO composition. The dissolution rate of the glasses in deionised water decreased with BaO content. The in vitro bioactivity tests were carried out in PBS and HBSS for 28 days under static conditions. The bioactivity of the samples was verified by XRD, SEM/EDS and FTIR techniques. Hydroxyapatite phases were formed on all the glass samples within seven days of immersion in HBSS and the bioactivity was found to improve with BaO content. The glasses without BaO and with 15 mol% BaO showed the hydroxyapatite phases within the immersion of 14 days in PBS whereas the glasses with 5 and 10 mol% BaO showed formation of amorphous hydroxyapatite phases. © 2018 Society of Glass Technology. All rights reserved.
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    Corrosion resistance and in-vitro bioactivity of BaO containing Na2O-CaO-P2O5 phosphate glass-ceramic coating prepared on 316 L, duplex stainless steel 2205 and Ti6Al4V
    (Institute of Physics Publishing helen.craven@iop.org, 2018) Edathazhe, A.B.; Shashikala, H.D.
    The phosphate glass with composition 11Na2O-15BaO-29CaO-45P2O5 was coated on biomedical implant materials such as stainless steel 316 L, duplex stainless steel (DSS) 2205 and Ti6Al4V alloy by thermal enamelling method. The structural properties and composition of glass coated substrates were studied by x-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive x-ray spectroscopy (EDS) analysis. The coatings were partially crystalline in nature with porous structure and pore size varied from micro to nanometer range. The polarization curve was obtained for uncoated and coated substrates from electrochemical corrosion test which was conducted at 37 °C in Hank's balanced salt solution (HBSS). The corrosion resistance of 316 L substrate increased after coating, whereas it decreased in case of DSS 2205 and Ti6Al4V. The XRD and SEM/EDS studies indicated the bioactive hydroxyapatite (HAp) layer formation on all the coated surfaces after electrochemical corrosion test, which improved the corrosion resistance. The observed electrochemical corrosion behavior can be explained based on protective HAp layer formation, composition and diffusion of ions on glass coated surfaces. The in-vitro bioactivity test was carried out at 37 °C in HBS solution for 14 days under static conditions for uncoated and coated substrates. pH and ion release rate measurements from the coated samples were conducted to substantiate the electrochemical corrosion test. The lower ion release rates of Na+ and Ca2+ from coated 316 L supported its higher electrochemical corrosion resistance among coated samples. Among the uncoated substrates, DSS showed higher electrochemical corrosion resistance. Amorphous calcium-phosphate (ACP) layer formation on all the coated substrates after in-vitro bioactivity test was confirmed by XRD, SEM/EDS and ion release measurements. The present work is a comparative study of corrosion resistance and bioactivity of glass coated and uncoated biomedical implants such as 316 L, DSS and Ti6Al4V. © 2018 IOP Publishing Ltd.