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    Item type:Publication,
    First report of apple mosaic virus infecting Rosa spp. in Pichincha province, Ecuador
    (Springer Science and Business Media LLC, 2020-08-24)
    María Lizzethe Paz
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    Yeturu Sivaprasad
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    Ligia Ayala
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    Karla Méndez
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    Item type:Publication,
    Evaluating the Influence of Hydrophobic Nano-Silica on Cement Mixtures for Corrosion-Resistant Concrete in Green Building and Sustainable Urban Development
    (MDPI AG, 2023-10-26)
    Mohammadfarid Alvansazyazdi
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    Fabricio Alvarez-Rea
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    Jhon Pinto-Montoya
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    ;
    Pablo M. Bonilla-Valladares
    <jats:p>The use of hydrophobic nano-silica particles in concrete for improved corrosion resistance and durability has been explored in recent years, and its potential impact on sustainable urban development and green building practices has been studied. The impact of substituting hydrophobic nano-silica particles for 2% of the cement weight in high-strength concrete mixes was investigated in this research. The study focuses on evaluating the physical-mechanical properties, including compressive strength, tensile strength, modulus of elasticity, and Poisson’s ratio. Additionally, the influence of these mixes on corrosion resistance is examined. The concrete designs feature a high strength of 42 MPa, and the hydrophilic nano-silica particles undergo functionalization processes to obtain hydrophobic properties. Contact angle measurements and water absorption tests confirm the hydrophobicity of the material. Physical, electrochemical, and electrical tests were conducted to determine the corrosion resistance contribution of the nano-silica particles when substituted at 2% of the cement weight. The research findings reveal that concrete containing nano-silica particles demonstrates improved physical-mechanical properties compared to other mixes. Incorporating nano-silica enhances concrete by accelerating hydration, increasing early-age strength, and providing hydrophobicity, resulting in improved physical-mechanical properties over other mixes. However, it was observed that the addition of hydrophobic and non-hydrophobic nano-silica tends to reduce corrosion resistance compared to concrete without these particles, despite exhibiting greater compactness. This suggests a direct influence of nano-silica on the corrosion phenomenon.</jats:p>
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    Item type:Publication,
    From Renewable Biomass to Water Purification Systems: Oil Palm Empty Fruit Bunch as Bio-Adsorbent for Domestic Wastewater Remediation and Methylene Blue Removal
    (MDPI AG, 2023-11-28)
    Cristina E. Almeida-Naranjo
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    ;
    Elizabeth Domínguez
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    Paola Gutiérrez
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    Vladimir Valle
    <jats:p>Oil palm empty fruit bunch fibers (OPEFBF), in three size ranges (small: 250–450 µm, medium: 450–600 µm, large: 600–800 µm), were investigated as a filter-bed material in biofilters for the removal of organic matter and nutrients. After saturation, these fibers (post) were used in the removal of methylene blue through batch processes. The batch adsorption tests included optimizing the adsorbent dosage (0.5–32.0 g/L) and contact time (2.5–60.0 min). Experimental data were fitted to various kinetic/isotherm models. Instrumental characterization of both raw and post fibers was conducted. Post fibers underwent morphological/compositional changes due to the presence of microorganisms and their byproducts. Efficiencies reached up to 94% for chemical oxygen demand (COD), 88.4% for total nitrogen and 77.2% for total phosphorus. In batch adsorption, methylene blue removal exceeded 90%, underscoring the effectiveness of small raw OPEFBF and large post OPEFBF. Kinetic models indicated that raw OPEFBF better fit the pseudo-first-order model, while post OPEFBF better fit the pseudo-second-order model. Both types of OPEFBF showed a good fit with the Freundlich model (higher R2, lower χ2 and SSE). Particularly, large post OPEFBF stood out as the most efficient adsorbent, achieving a maximum adsorption capacity of 12.02 mg/g for methylene blue. Therefore, raw/post OPEFBF could be an alternative to remove contaminants from wastewater.</jats:p>