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Papers by luiz fernando gorup

Chemical engineering research & design, Aug 1, 2023

Journal of prosthodontic research, 2015

The aim of this study was to investigate the susceptibility of Candida albicans and Candida glabr... more The aim of this study was to investigate the susceptibility of Candida albicans and Candida glabrata biofilm development, in their intermediate and maturation stages, to the influence of silver nanoparticles (SN). Methods: SN (5 nm) suspensions were synthesized via reduction of silver nitrate by a solution of sodium citrate. These suspensions were used to treat Candida biofilms for five hours, grown on acrylic surfaces for 24-h (intermediate stage) and 48-h (maturation stage), and their efficacy was determined by total biomass (using crystal violet staining) and colony forming units (CFUs) quantification. Results: SN promoted significant reductions (p < 0.05) in the total biomass and number of CFUs of Candida biofilms, ranging from 23% to 51.5% and 0.63 to 1.59-log 10 , respectively. Moreover, there were no significant differences in the total biofilm biomass (p > 0.05), when the different stages of biofilm development (24 or 48 h) were exposed to SN. Comparing the number of CFUs between 24-and 48-h biofilms treated with SN, a significant difference (p < 0.05) was found only for the C. albicans 324LA/94 strain. Conclusions: In general, the intermediate and maturation stages of biofilm development do not interfere in the susceptibility of C. albicans and C. glabrata biofilms to SN. These findings are fundamental for the deployment of new therapies aimed at preventing denture stomatitis.

Elsevier eBooks, 2023

New nanocomposites are currently being developed that have real industrial poten-tialÐloading a p... more New nanocomposites are currently being developed that have real industrial poten-tialÐloading a polymer with a small (ca. 5 %) amount of inorganic nanoparticles (the Figure shows a polypropylene±clay hybrid composite) is expected to give rise to significant improvement to the materials properties with only a minor increase in cost. Recent developments in this area are summarized here.

Ceramics International, Feb 1, 2019

The structure, morphology and surface roughness of Bi 12 TiO 20 (BTO) thin films grown on R-sapph... more The structure, morphology and surface roughness of Bi 12 TiO 20 (BTO) thin films grown on R-sapphire by pulsed laser deposition (PLD) were studied at different substrate temperatures, target-substrate distances, oxygen pressures and laser-pulse repetition rates. Although the substrate temperature seems to be the most important experimental parameter, the gas pressure and the target-substrate distance played important role on the phase formed and film thickness, with a significant effect of the laser-pulse repetition rate on the films thickness and preferred orientation of the deposited film. Single-phase γ-Bi 12 TiO 20 was obtained on substrates at 650 o C, while several BTO metastable phases were observed in films deposited on substrates at temperatures between 500 and 600 o C. By the first time, thin films of pure and textured δ-Bi 12 TiO 20 were successfully growth on substrates at 450 o C. When annealed, all the films deposited at lower temperatures resulted in the thermodynamically stable γ-Bi 12 TiO 20 .

Elsevier eBooks, 2016

Biofilms may compromise wound healing, because of their tolerance to antimicrobials. Control of b... more Biofilms may compromise wound healing, because of their tolerance to antimicrobials. Control of biofilms has been achieved with combinations of drugs and alternative antimicrobial agents. Silver nanoparticles have been the subject of substantial research for medical and health applications, and there is a remarkable international effort underway to verify their safety and to understand how these nanoparticles effectively kill several microorganisms. The use of silver nanoparticles in natural products with medicinal importance is a relatively new concept and is a widely accepted technology with rapid production capabilities and minimum impact on human health and environmental quality. This chapter presents the importance of studying biofilms, especially in chronic wounds using in vitro models, and emphasizes the potential green synthesis of silver nanoparticles.

Colloids and Interfaces

This study focuses on the synthesis of silver nanoparticles (AgNPs) at different high concentrati... more This study focuses on the synthesis of silver nanoparticles (AgNPs) at different high concentrations and investigates their physicochemical properties, antimicrobial activity, and cytotoxicity. AgNPs were synthesized using the alcohol reduction process, involving the reduction of AgNO3 and its subsequent stabilization via PVP at 80 °C for 4 h. The AgNO3/PVP molar ratio and the average molecular weight were modified in this study. Characterization analyses revealed that the synthesized AgNPs exhibited characteristic surface plasmon resonance absorption peaks at approximately 415 nm, as observed in the UV–Vis spectrum. The results presented in X-ray diffractograms confirmed the face-centered cubic structure of metallic Ag in the nanoparticles. The nanoparticles demonstrated uniform size and shape, with controllable dimensions ranging from 3 to 800 nm. Regarding antimicrobial activity, the MIC solutions exhibited higher potency against the planktonic cells of Candida albicans. The dete...

AppliedChem

The CO2 reduction by solar means has been discussed as an alternative to emission abatement, a fu... more The CO2 reduction by solar means has been discussed as an alternative to emission abatement, a fundamental topic for sustainable, carbon-free production in the future. However, the choice of efficient systems, starting with the catalysts, is still a critical issue, especially due to the poor activity of available options. Polyoxometalates have been extensively studied as promising photocatalysts due to their semiconducting properties. Nevertheless, the synthetic conditions of polyoxoniobate are stringent due to the low reaction activity of Nb species, the lack of soluble precursors, and the narrow pH range. Unlike the literature, in the present study, we report a simple polyoxoniobate synthesis method. This synthesis method has some remarkable features, such as low processing time and temperature and good activity and selectivity in the CO2 photoreduction process. The results revealed an outstanding efficiency for the CO2 reduction reaction with a high selectivity of CO2 to CO conve...

Recent Advances in Complex Functional Materials, 2017

The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Handbook of Energy Materials, 2022

International Journal of Photoenergy, 2018

Environmental problems related to the generation of wastewater contaminated with organic compound... more Environmental problems related to the generation of wastewater contaminated with organic compounds and the emissions of pollutants from fuel burning have become major global problems. Thus, there is a need for the development of alternative and economically viable technologies for the remediation of the affected ecosystems. Therefore, this work describes the preparation and characterization of a Ti(OH)4 catalyst with the modified surface for application in the photodegradation of organic compounds (methylene blue (MB) dye and the drug amiloride (AML)) and in the artificial photosynthesis process. Characterization results reveal that peroxo groups on the surface of the catalyst had a great influence on the optical properties of the Ti(OH)4 and consequently in its photocatalytic property. This catalyst showed a high photocatalytic activity for the degradation of organic pollutants under visible radiation, reaching approximately 98% removal of both the dye and the drug in 150 min of re...

ACS Applied Nano Materials, 2019

This study systematically investigated the electronic, structural, and optical properties of MgTi... more This study systematically investigated the electronic, structural, and optical properties of MgTiO 3 (MTO), LaNiO 3 (LNO), and MgTiO 3 /LaNiO 3 (MTO/LNO) nanostructured films grown on Si (100) substrates by the pulsed laser deposition (PLD) method. The structural characterizations obtained by X-ray diffraction revealed a preferred (003) orientation for the MTO film, while the LNO film was polycrystalline. The diffraction peaks corresponded to a rhombohedral structure, which was confirmed by micro-Raman (MR) spectroscopy for both nanostructured films. The MTO/LNO heterostructure was polycrystalline and exhibited the diffraction peaks of both the MTO and the LNO phases. Additionally, the results revealed that the LNO films did not have a significant photoluminescence (PL) emission, while an intense broad infrared luminescence centered at 724 nm appeared for the MTO nanostructured film. Surprisingly, for the MTO/LNO heterostructure, the PL emission profile exhibited a dualcolor emission with an intense broad luminescence in the blue region (maximum centered at 454 nm) and an intense near-infrared emission (maximum centered at 754 nm), respectively, Page 1 of 26 ACS Paragon Plus Environment ACS Applied Nano Materials mainly because of the effect of interface defects, which induced a significant change in the PL behavior. Therefore, our experimental results correlated with the theoretical simulations based on the periodic density functional theory formalism and contributed to a deeper understanding of the charge/energy transfer processes occurring in the MTO/LNO/Si interfaces, and toward the exploitation of the close relationship between the structure and properties of these new functional materials.

CERN European Organization for Nuclear Research - Zenodo, Sep 26, 2022