Examinando por Materia "Hydrothermal treatment"

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    Evaluation of methods for centrifugation and hydrothermal treatment for obtaining of calcium phosphate nanoparticles
    (Universidad del Valle, 2017-01-30) Buitrago Vásquez, Maritza; González Ocampo, Jazmín I.; Ossa Orozco, Claudia P.
    (Eng) Calcium phosphates are ceramics materials used in the manufacture of bone substitutes, due to their composition which is similar to the bones, they are bioactive, osteoconductivity and works in favor of forming porous structures, allowing vascularization and cell adhesion; furthermore they stand out for their biocompatibility. They are currently employed in the replacement of bone tissue in several clinical applications such as bone cements and fillers. Within this paper, nanoparticles of different calcium phosphates were obtained and characterized by two methods reported in the literature, centrifugation and hydrothermal treatment from precipitation reaction. The powders were characterized by XRD and FE-SEM. The results prove that both methods are suitable for the obtaining of nanoparticles of calcium phosphates, which is verified in the micrographs obtained where different morphologies are observed. Particles in nanoscale for most powders obtained have average diameter between 44.98 and 82.21 nm and average length between 123.91 and 151.48 nm. Diffractograms by both methods show the presence of calcium phosphates with different potential applications in bone tissue engineering, for the hydrothermal method was found that the temperature and time are major factors during stabilizing of phases. From this study it was concluded that both synthesis methods are suitable for obtaining nanoparticles and stabilization of different phases of calcium phosphate, being protocols 1, 3 and 4 the most suitable for biomedical applications.
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    PublicaciónAcceso abierto
    Postharvest treatments for control of Conotrachelus dimidiatus (Coleoptera: Curculionidae) in guava (Psidium guajava).
    (Universidad del Valle, 2017-06-30) Vargas Madríz, Haidel; Martínez Damián, María Teresa; Mena Nevárez, Gustavo; Sociedad Colombiana de Entomología - Socolen; Universidad del Valle
    Guava (Psidium guajava) is one of the most common fruit trees cultivated in Latin America; however, its production is delimited by different insect pests that affect fruit quality, including the guava weevil Conotrachelus dimidiatus. This study assessed the effects of two post-harvest treatments (hydrothermal and temperature storage) in the control of C. dimidiatus, as well as physicochemical variables of treated guava fruits. The hydrothermal treatment presented mortality of larvae 70 minutes after immersion, while mortality of larvae was observed after the six days of evaluation in the temperature treatment. In both post-harvest treatments, the variables titratable physicochemical acidity and vitamin C did not present significant statistical differences among treatments; whereas, the degrees °Brix and ionic acidity showed significant differences with respect to the control. For the hydrothermal treatment, a decrease in the time of immersion is suggested in order to minimize or void the effects of the treatment tested. Regarding temperature, it was observed that the presence of larvae of C. dimidiatus in fruit leads to a reduction in the sugar content. Hence, more studies are needed to determine ideal temperatures in which the effects of the treatments are minimal or void on the physicochemical properties of guava fruit. These may be considered as an alternative to post-harvest control for this insect.