Browsing by Author "Morales-Morales, Jimmy Alexander"
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Item Effect of modification substrate on the microstructure of hydroxyapatite coating(Institute of Physics Publishing, 2017-01-25) Realpe-Jaramillo, J.; Morales-Morales, Jimmy Alexander; González-Sánchez, J.; Cabanzo, Rafael; Mejía-Ospino, Enrique; Rodríguez-Pereira, JhonatanBioactive hydroxyapatite (HA) coatings were fabricated by a precipitation, sol-gel and dip-coating method. The effects of the aging time and the base used to adjust pH and substrate materials on the phases and microstructures of HA coatings were studied by field emission scanning electron microscopy FESEM, energy dispersive spectroscopy EDS, X-ray photoelectron spectroscopy XPS, and the vibrations of the phosphate groups were determined by Raman spectroscopy. The results showed that all the films were composed of the phases of TiO2 and HA. With coated titanium substrate with TiO2, the crystallinity of the HA coating increases, the structure became more compact and the Ca/P ratio increased because of the loss of P in the films. The addition of sodium hydroxide (adjusting the pH level to about 10) can increase the HA content in the coating. XPS and EDS results for steel substrate and titanium showed poor calcium content as obtained with a Ca/P ratio of 1.38 and 1.58, respectively, composition is similar to that of natural apatite. However, spectroscopic results suggest the presence of a mixture of hydroxyapatite and octacalcium phosphate. The different substrate materials have a high influence on the microstructure of the separated double films. However, hydroxyapatite nanopowders coatings were obtained using a simple method, with potential biomedical applications. © Published under licence by IOP Publishing Ltd.Item Effect of modification substrate on the microstructure of hydroxyapatite coating(Journal of Physics: Conference Series, 2017) Realpe-Jaramillo, J.; Morales-Morales, Jimmy Alexander; González-Sánchez, J. A.; Cabanzo, Rafael; Mejía-Ospino, Enrrique; Rodríguez−Pereira, J.Bioactive hydroxyapatite (HA) coatings were fabricated by a precipitation, sol-gel and dip-coating method. The effects of the aging time and the base used to adjust pH and substrate materials on the phases and microstructures of HA coatings were studied by field emission scanning electron microscopy FESEM, energy dispersive spectroscopy EDS, X-ray photoelectron spectroscopy XPS, and the vibrations of the phosphate groups were determined by Raman spectroscopy. The results showed that all the films were composed of the phases of TiO2 and HA. With coated titanium substrate with TiO2, the crystallinity of the HA coating increases, the structure became more compact and the Ca/P ratio increased because of the loss of P in the films. The addition of sodium hydroxide (adjusting the pH level to about 10) can increase the HA content in the coating. XPS and EDS results for steel substrate and titanium showed poor calcium content as obtained with a Ca/P ratio of 1.38 and 1.58, respectively, composition is similar to that of natural apatite. However, spectroscopic results suggest the presence of a mixture of hydroxyapatite and octacalcium phosphate. The different substrate materials have a high influence on the microstructure of the separated double films. However, hydroxyapatite nanopowders coatings were obtained using a simple method, with potential biomedical applications.Item Effect of substrate nature on the electrochemical deposition of calcium-deficient hydroxyapatites(Institute of Physics Publishing, 2017-01-25) Gualdrón-Reyes, A. F.; Domínguez-Vélez, V.; Morales-Morales, Jimmy Alexander; Cabanzo, Rafael; Meléndez, A. M.Calcium phosphates were obtained by reducing nitrate ions to produce hydroxide ions on TiO2/stainless steel and TiO2/titanium electrodes. TiO2 coatings on metallic substrates were prepared by sol-gel dip-coating method. The morphology of deposits was observed by FESEM. Chemical nature of calcium phosphate deposits was identified by Raman micro-spectroscopy and FESEM/EDS microanalysis. Electrochemical behavior of nitrate and nitrite reduction on stainless steel and titanium electrodes was studied by linear sweep voltammetry. In addition, voltammetric study of the calcium phosphate electrodeposition on both electrodes was performed. From these measurements was selected the potential to form a calcium phosphate. A catalytic current associated to nitrate reduction reaction was obtained for stainless steel electrode, leading to significant deposition of calcium phosphate. Ca/P ratio for both substrates was less than 1.67. The formation of calcium deficient hydroxyapatite was confirmed by Raman spectroscopy. © Published under licence by IOP Publishing Ltd.Item Electrochemical reduction processes on glassy carbon electrode of 2-Amino-4-phenylthiazoles.(Institute of Physics Publishing, 2018-12-18) Morales-Morales, Jimmy Alexander; Salazar-Osorio, M.; Florez-López, E.In this work the electrochemical reduction of the compounds 2-Amino-4-(4-R-phenyl)thiazoles (1a, R =-H and 1b, R =-NHCOCH 3 ) was performed by cyclic voltammetry in dimethylsulfoxide (DMSO) + 0,1 M tetraethylammonium tetrafluoroborate (TEABF 4 ) and tetrabutylammonium hexafluorophosphate (TBAPF 6 ). Two reduction signal were observed, the Ic wave (EpIc =-2.52 V) and wave IIc (EpIIc =-2.77 V) due to an electron transfer of the electrogenerated product in the Ic wave. The change of substituent influences the electrochemical behaviour, showing that an electrodonating substituent causes a higher energy requirement for the reduction of 1b, which became evident in the more negative potential, with respect to 1a. Additionally, it was observed that the peak potential in the first reduction signal Ic wave shifted to more negative values as the potential sweep rate was higher and this was indicative of an irreversible behaviour. A larger salt such as TBAPF 6 causes a decrease in the intensity of peak reduction currents, contrary to what was shown by a smaller salt such as TEABF 4 . Also for both compounds, the cathodic peak potential of wave Ic and IIc is influenced by the effect of the size of salt used. A smaller salt favoured the electrochemical reduction of both heterocyclic compounds. © Published under licence by IOP Publishing Ltd.Item A preliminary study of cyclic voltammetry in glassy carbon electrode. Redox Behaviour of 2-Amino-4-phenylthiazoles(Institute of Physics Publishing, 2018-12-10) Morales-Morales, Jimmy Alexander; Rios-Acevedo, J. J.; Florez-López, E.In this work a voltammetric study of the reduction processes of five substituted 2-Amino-4-(4-X-phenyl) thiazoles (-X =-H,-OCH 3 ,-CH 3 ,-Cl,-NO 2 ) in dimethylsulphoxido was performed. In the potential range considered (-2.0 to-2.9 V vs Ag+/AgCl), one signal (Ic) were detected, which was associated with the electrochemical reduction of the corresponding of the heterocycle compound. The voltammetric analysis at the reduction signal showed that when in-creasing the sweep speed (0.1 < v < 1.0 Vs -1 ), an oxidation signal associated with the Ic wave was not observed. The linear dependence of the peak current with respect to the root of the velocity of the Ic wave, showed that this was a process controlled by diffusion and showed an apparently irreversible behavior. Peak potential shifted to more negative values as the potential sweep speed was higher; this was indicative of irreversible behavior in this signal. The substitution changes influenced the electrochemical behavior, evidencing that a substituent, as in this case methoxy group compound-OCH 3 , causes a greater energetic demand for the reduction of the thiazole derivative it becomes evident in the most negative potential, with respect to the derivative without substituent-H. This was new evidence of the behavior electrochemical of 2-Amino-4-(4-X-phenyl) thiazoles derivates which had not been reported for these compounds. © Published under licence by IOP Publishing Ltd.Item Study of the electrochemical oxidation of 2-Thiazolamine and 2-Oxazolamine on a platinum wire as working electrode(Institute of Physics Publishing, 2018-12-10) Morales-Morales, Jimmy Alexander; Villamarin, A. F.; Florez-López, E.; Rios-Acevedo, J. J.The electrochemical oxidation of 2-aminothiazole (2AT) and 2-aminooxazole (2AO) was studied by means of the cyclic voltammetry technique (VC), on a Pt wire as working electrode. An anodic wide peak centred at 0.79V was observed and 0.98V (Ia wave) caused by the oxidation of the 2AT and 2AO compounds and the formation of cationic radicals on the clean surface of the electrode, respectively. During the studies of (VC) in a small range of exploration speeds, the oxidation signal increased with the increase in speed and moved to more positive potential values. This dependence of the potential with respect to the potential sweep speed indicated a controlled diffusion of the system of an irreversible nature. At T = 298K, from the electrochemical oxidation of 2 AT, a thin coating film with a light brown color was obtained on the surface of the Pt wire. However, in the electroxidation of 2 AO, that result was not evident. While the 2AT electroxidation product loses conductivity, in the case of the 2AO compound, the electrogenerated product on the surface of the platinum wire maintains the conductive properties. © Published under licence by IOP Publishing Ltd.Item Synthesis of hematite α-Fe2O3 nano powders by the controlled precipitation method(Ciencia En Desarrollo, 2017) Morales-Morales, Jimmy AlexanderIncreased attention has been paid to the synthesis of hematite nanoparticles recently due to its properties and application in various fields of modern technology. The aqueous route has been found to be simpler and more versatile than the non-aqueous routes. In this study nanopowder of a-Fe2O3 (hematite) were synthesized by controlled precipitation method in three stages: precipitation of precursors, washing and calcination. The precipitation was controlled with ferric chloride as precursor, and sodium hydroxide as precipitant, in constant agitation and pH 6. It tested different reaction times: 1 and 2 days, and after 2 day of reaction it was concluded that it is possible to obtain hematite. The products obtained from the reaction were washed by centrifugation, dried at 80 ◦C, and were calcined at temperature of 425 ◦C, for four hours. To characterize the product obtained in the synthesis, it has been used FT-IR, SEM and RAMAN techniques. Samples with two days of reaction, washed and calcination at 425 ◦C are associated a mixture of hematite and magnetite and maghemite, with nearly morphology from plate-like shaped sphere and aggregates are formed by hemispherical primary particles whose size, apparently, is on the order of nanometers.