Navegando por Autor "Carreño, Neftalí Lênin Villarreal"

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Antimicrobial activity from polymeric composites-based polydimethylsiloxane/TiO2/GO: evaluation of filler synthesis and surface morphology
(Springer, 2016-11-04) Correa, Camila F.; Santana, Luiza R.; Silva, Ricardo M.; Noremberg, Bruno S.; Lund, Rafael G.; Ribeiro, Juliana S.; Motta, Fabiana Villela da; Delmonte, Maurício Roberto Bomio; Nascimento, Rubens Maribondo do; Carreño, Neftalí Lênin Villarreal
Antimicrobial substances may be used to reduce hospital infections and inhibit food contamination, thus ensuring the safety and well being of humans. The objective of this study was to evaluate the antimicrobial activity of the polymeric nanocomposites polydimethylsiloxane (PDMS) embedded with two types of fillers based on titanium dioxide (commercial TiO2 P25 versus TiO2 via facile Micro- wave-assisted hydrothermal-MAH synthesis) and graphene oxide (GO). The nanocomposites were prepared using different compositions, concentrations, and functionalizations (PDMS/TiO2/GO; PDMS/TiO2 and PDMS/GO). The antimicro- bial activity of the samples was evaluated for different treatments on Candida albicans, Staphylococcus aureus, and Enterococcus faecalis, by a modified direct contact test (mDCT). The samples were also evaluated on surface morphology and the roughness as a function of active particles insertion by atomic force microscopy (AFM). Most of the PDMS films whose polymer was embedded with GO and hydrothermal TiO2 showed the highest inhibition growth of bacteria and Candida over 24 h. After 24 h, F, J, and H samples showed the best antibacterial activity, whereas E showed the best antifungal activity. The results indicated that the nanocomposites PDMS/GO/TiO2MAH and PDMS/GO sample enhanced antimi- crobial activity in the treatments tested, therefore they were functional for con- taminant reduction
Biofilms of cellulose and hydroxyapatite composites: Alternative synthesis process
(SAGE Publications, 2020-09-01) Pieper, Cari M.; Rosa, Wellington L. O. da; Lund, Rafael G.; Silva, Adriana F. da; Piva, Evandro; Salas, Mabel M. S.; Maron, Guilherme K.; Delmonte, Maurício Roberto Bomio; Motta, Fabiana Villela da; Carreño, Neftalí Lênin Villarreal
A new biofilm of cellulose coated with hydroxyapatite particles have been prepared using a simple, fast and low temperature process based on a microwave-assisted hydrothermal synthesis. The cellulose used as matrix of the biocomposite was extracted from banana stems residues. The hydroxyapatite coating was performed using calcium nitrate tetrahydrate, phosphoric acid, and 1,2-ethylenediamine dispersed in a cellulose/water solution, with posterior microwave-assisted hydrothermal synthesis, for 5 min at 140°C. The chemical, structural, thermal, and morphological properties of the composites were investigated by X-ray diffraction, infrared spectroscopy, thermogravimetry and field emission scanning electron microscopy. Results showed that the methodology was effective to produce high quality composites, with good thermal stability. Cell viability tests indicated that the cellulose/ Hap films were not cytotoxic
Fast and simultaneous doping of Sr0.9−x−y−zCa0.1In2O4:(xEu3+, yTm3+, zTb3+) superstructure by ultrasonic spray pyrolysis
(Elsevier, 2019-09) Paskocimas, Carlos Alberto; Santiago, Anderson de Azevedo Gomes; Lovisa, Laura Ximena; Medeiros, P. N.; Li, Maximo Siu; Carreño, Neftalí Lênin Villarreal; Silva, Elson Longo da; Delmonte, Maurício Roberto Bomio; Motta, Fabiana Villela da
In the present work, Sr0.9−x−y−zCa0.1In2O4:(xEu3+, yTm3+, zTb3+) particles were synthesized by the ultrasonic spray pyrolysis (USP) method to obtain a single-phase white phosphorus formed by six different cations in solution within the lattice (superstructure). The samples were also structurally and morphologically characterized by X-ray diffraction (XRD) techniques and by field emission scanning electron microscopy (FE-SEM). The photoluminescent behavior and the characteristics of the emitted colors were studied by the variation in the codoping of the rare earth elements. The Sr0.9Ca0.1In2O4 sample showed a near blue color emission, but all codoped samples showed emission in white with very close chromaticity coordinates to the standard white (x = 0.33 and y = 0.33). The Tm3+ → Tb3+ (ET1), Tm3+ → Eu3+ (ET2) and Tb3+ → Eu3+ (ET3) Energy Transfers were proposed and are considered necessary for adjusting and controlling the desired color properties

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Navegando por Autor "Carreño, Neftalí Lênin Villarreal"