Photocatalytic reduction of Cr(VI) in wastewater using TiO₂ coatings synthesized by plasma electrolytic oxidation (PEO): Influence of duty cycle and EDTA addition N.V. Naranjo-Castaño, M. Chacón-Chamorro, F.N. Rosero-Rodríguez, F.N. Jiménez-García, N. Alzate Acevedo, Y.P. García-Gallego, C.A. Lubo-Mestanza, J.C. Riaño-Rojas, E. Restrepo-Parra Next Materials, 2026 The contamination of water bodies with hexavalent chromium (Cr(VI)) poses a serious environmental threat due to its toxicity and persistence. This study investigates the photocatalytic efficiency of TiO₂ coatings synthesized by plasma electrolytic oxidation (PEO) on titanium substrates under varying duty cycles (5 %, 20 %, and 35 %) and evaluated under UVC irradiation (256 nm). The coatings were characterized by XRD, SEM, AFM, and UV-Vis spectroscopy, and SEM images were analyzed using Fourier Transform methods. Results showed that coatings produced at 20 % and 35 % duty cycles exhibited enhanced Cr(VI) reduction to Cr(III), with 20 % offering the best balance between performance and energy consumption. The inclusion of EDTA in the photocatalysis process significantly improved Cr(VI) removal. Structural analysis indicated that higher duty cycles promoted rutile phase formation and a qualitative evolution of surface morphology; porosity was discussed qualitatively based on SEM at the magnification employed. The Fourier Transform analysis of SEM images was used as a complementary qualitative descriptor consistent with the observed performance trends, supporting the development of optimized photocatalytic materials for wastewater treatment applications. • PEO TiO₂ coatings enhance Cr(VI) photocatalysis efficiency • Fourier Transform of SEM images provides a qualitative descriptor consistent with coatings' catalytic performance. • 20 % duty cycle in TiO₂ films offers best efficiency vs. energy consumption balance. • Rutile phase contribution and surface morphology evolution enhance Cr(VI) removal via photocatalytic coatings • EDTA addition during photocatalysis boosts Cr(VI) removal from solution.
Sustainable fibercement reinforced composites: flexural enhancement and microstructural evolution with rice husk-derived silica micro and nanoparticles Daniel Fernando Hincapié Rojas, Posidia Pineda-Gomez, Francy Nelly Jiménez García, Astrid Lorena Giraldo Betancur, Diego Germán Espinosa-Arbelaez, O Moscoso Londoño Oxford Open Materials Science, 2026 Fibercement is a lightweight and highly resistant material composed of cement, additives, and fibers and is mainly used in lightweight construction systems. This study investigates the effect of incorporating micro and nanosilica particles derived from rice husk into fibercement composites, aiming to enhance their mechanical performance and sustainability. Fibercement samples were prepared with varying silica concentrations (0, 1, 3, 5, and 7 wt.%) and cured for 28 days under ambient conditions. The composites were characterized in terms of density, water absorption, flexural strength, thermal stability, morphology, and phase composition. X-ray diffraction showed the formation of hydration products such as tobermorite, and with silica addition reducing portlandite content, indicating a pozzolanic reaction. Scanning electron microscopy confirmed improved fiber-matrix entanglement and densification of the microstructure. Thermogravimetric analysis corroborated the reduction in portlandite and carbonate phases with silica addition. The flexural strength improved with silica addition: samples with 5 wt.% micro and nano silica exhibited increases of 48.1% and 71.6%, respectively, compared to the control sample. Although higher silica contents slightly increased water absorption and reduced density, all samples met the NTC 4694 standards for fibercement products. These results demonstrate that rice husk-derived silica, especially in nanoparticle size, enhances the mechanical and structural performance of fibercement composites, offering a sustainable alternative for the construction industry.
Measurement of Surface Deformation in NiTi Endodontic Reciprocating Instruments Manufactured by Machining Yenny Marcela Orozco‐Ocampo, César Augusto Álvarez Vargas, Francy Nelly Jiménez‐García, Daniel Escobar‐Rincón, Paola Ximena Jaramillo‐Gil Microscopy Research and Technique, 2025 This study aimed to develop a methodology to quantify the surface deformation of WaveOne‐Gold‐Primary instruments after in vitro use. Fifteen reciprocating instruments were used to prepare artificial canals composed of diallyl‐phthalate, bisphenol‐A, and duralumin (n = 5 per group). Optical microscopy was employed to determine Euler‐Almansi strains, scanning electron microscopy (SEM) was used to identify shear bands and characterize fracture surfaces, and energy‐dispersive X‐ray spectroscopy (EDS) was used to analyze elemental composition. An ANOVA (95%) was conducted to assess significant differences in the strains. The instruments used in polymer canals exhibited untwisting and pronounced elongation, indicative of plastic deformation associated with ductile fractures. Although, atomic percentages of Ni and Ti remained relatively stable, a slight reduction in Ni was observed in the coating of the sterilized instruments. A mathematical model was proposed to correlate the strains with the number of pecks. This methodology provides a robust framework for measuring the deformation of machined NiTi instruments, contributing to a better understanding of their failure and potential prediction implications.
Preparation and Characterization of Novel Hydroxyapatite/Montmorillonite/Gelatin-Based Composites with Bone Remineralizing Potential José M. Posada-Lotero, Maby M. Martínez-Garzón, Milton Rosero-Moreano, Francy N. Jiménez-García, Laura R. Giraldo-Torres, Daniel F. Hincapié-Rojas ACS Omega, 2025 Bone wear caused by injury or deterioration due to age leads to the use of autologous and allogeneic implants that are sometimes rejected by the body. Currently, work is being carried out on the development of composites that induce bone repair. In this study, composites with montmorillonite clay (MMT), hydroxyapatite (HAp), and gelatin were prepared. Initially, various ratios of HAp/MMT composites (1:1, 2:1, and 1:2) were examined, and the 2:1 ratio provided a better biological response. Finally, the HAp/MMT/Gel ternary mixtures were prepared using different percentages of gelatin: 10, 50, and 90% and maintaining the 2:1 HAp/MMT ratio. All materials were assayed in a biomineralization proof using simulated biological fluids. In the HAp/MMT/Gel diffraction pattern, the peaks associated with MMT and HAp are preserved at 20 and 32° in 2θ, respectively; the addition of gelatin promotes structural changes. Biocompatibility studies show that there are no morphological changes in the platelets since it does not exceed 5 μm of pseudopodia, which suggests that there is no rejection of the material. On the other hand, the biomineralization study, followed by SEM and FTIR characterization, showed the generation of apatite and demonstrated its potential application in bone tissue regeneration.
Spearmint Extract as a Sustainable Corrosion Inhibitor Through Advanced Spray Coating Applications Manuela Salazar Iglesias, Maria Valentina Suárez León, Daniel Alejandro Pineda Hernandez, Pedro José Arango Arango, Francy Nelly Jiménez García, Elisabeth Restrepo Parra Coatings, 2024 In this research, the high efficacy of Mentha spicata L. extract, commonly known as spearmint, as a corrosion inhibitor with an efficacy rate of 86.98% is highlighted. Analytical techniques, such as scanning electron microscopy (SEM) to obtain a detailed morphological view, Fourier transform infrared spectroscopy (FTIR) to identify the functional groups of flavonoids, and electrochemical impedance spectroscopy (EIS) and Tafel plots for a corrosion assessment, were employed. This study pioneers a greener alternative to traditional corrosion inhibition methods. The distinctive aspect of this research is the innovative spray coating application method used to deliver the spearmint extract onto structural steel. This method involves the strategic use of an airbrush for spray coating, ensuring the uniform and efficient deposition of the organic inhibitor, thus forming a protective barrier against corrosion. This spray coating technique is emerging as an innovative approach for the industrial application of natural corrosion inhibitors, demonstrating significant advances in the corrosion resistance of coated steel. The results not only corroborate the efficacy of natural inhibitors, but also highlight the critical role that sophisticated application techniques play in improving their industrial viability. This methodological innovation presents a pathway to sustainable practices in corrosion management, prioritizing environmental protection and ecological footprint reduction in the quest for corrosion mitigation.
Factors influencing NiTi endodontic file separation: A thematic review Yenny Marcela Orozco-Ocampo, Daniel Escobar-Rincón, Francy Nelly Jiménez-García, César Augusto Álvarez-Vargas, Paola Ximena Jaramillo-Gil Dental and Medical Problems, 2024 Nickel-titanium (NiTi) file separation during endodontic treatment is an undesirable event. This phenomenon needs to be understood by knowing the factors influencing fracture in endodontic files. There is a large amount of literature where these factors and their influence have been studied, increasing the knowledge about the mechanisms involved, mainly related to wire technology, file shapes and geometry, operator manipulation, the anatomy of the root canal, and the irrigation and sterilization processes. As many factors are involved, the complexity of the fracture phenomena increases and the isolated correlation of one factor with the file fracture becomes a small part of comprehending the separation phenomena. This thematic review aims to compile important reports from 2014 to 2022 on the factors influencing NiTi file separation. The information obtained was classified into wire technology, file geometry, operational aspects, irrigation and sterilization, and anatomy. For this purpose, the Scopus, Web of Science and ScienceDirect databases were consulted using a search string. Filters were applied to consolidate the final set of relevant papers covering the subject of factors influencing endodontic file separation. It was found that the fracture of NiTi files incorporates different mechanisms that operate simultaneously during the endodontic procedure and strongly affect the instrument performance. The collected information promotes good practices to prevent file separation.
Effect of the addition of silica obtained from rice husk on physicochemical and mechanical properties of fibercement D.M. Gomez Mejia, D.F. Hincapie-Rojas, F.N. Jimenez-Garcia, César Augusto Alvarez Vargas Heliyon, 2023 After replacing asbestos with other types of fibers used as reinforcement of cementitious matrices, it has been found that rice husk, an agro-industrial waste with high silica content, can be used to improve the properties of fibercement. In this work, the effect of adding different forms of silica (rice husk, rice husk ash, and silica microparticles) on fibercement's physicochemical and mechanical properties was investigated. Rice husk ash and silica microparticles were extracted from the rice husk incineration and acid leaching process. The chemical composition of silica was determined by X-Ray Fluorescence, and the ash leached with hydrochloric acid was found to contain more than 98% silica. Cement, fiberglass, additives, and different forms of silica were used to manufacture fibercement specimens in their different forms. Concentrations of 0%, 3%, 5%, and 7% were taken for each form of silica, and four replicates were performed. The setting time was 28 days, during which absorption, density, and humidity tests were performed. Experiments were statistically analyzed at a 95% confidence value, and it was determined that there are significant differences in the compressive resistance, density, and absorption in relation to the type of additive and the interaction between the type of additive and its percentage of addition, but not whit percentage of addition. It was found that the fibercement specimens with 3% of rice husk present a modulus of elasticity of 9.4% higher than de control sample. The use of rice husk as an additive in fibercement composites seems to be interesting because these agro-industrial wastes are inexpensive and easily available everywhere to utilize in the cement industry and also helpful in reducing environmental pollution due to their cost and the positive effect on their properties.
Scenario Analysis of an Electric Power System in Colombia Considering the El Niño Phenomenon and the Inclusion of Renewable Energies Juliana Restrepo-Trujillo, Ricardo Moreno-Chuquen, Francy Jiménez-García, Wilfredo Flores, Harold Chamorro Energies, 2022 This paper develops and analyzes four energy scenarios for Colombia that consider the El Niño phenomenon and the inclusion of renewable energies in the energy generation matrix for the period 2020–2035. A comparative analysis is presented between the results of the different scenarios proposed. The most relevant finding is the use of the reserve margin as an indicator of system reliability. A scenario which included 7214 MW of large-scale non-conventional renewable energy, 10,000 MW of distributed generation, and 12,240 MW of hydroelectric power was assumed, with a reserve margin of over 50%. Additionally, it was found that for the scenarios in which a generation capacity with non-conventional renewable energies of less than 10,000 MW in 2034 was assumed, the reserve margin of the system in the seasons of the El Niño phenomenon will be less than historical records of the system. Alternatively, it was found that the scenarios in which the inclusion of at least 9600 MW of the electric power generation capacity of non-conventional renewable energies proposed by 2034 offer benefits in the reduction in greenhouse gas (GHG) emissions, which contributes to the achievement of the emission reduction objectives of the Paris Agreement.
