RESUMEN Los materiales a base de silicato de calcio han demostrado ser bioactivos debido a su capacidad para producir apatita carbonatada biológicamente compatible. El objetivo de este estudio fue analizar la bioactividad de Biodentine™ y MTA Repair HP® en contacto con discos de dentina humana, que se obturaron y dividieron aleatoriamente para formar cuatro grupos: grupo 1 Biodentine™, grupo 2 MTA Repair HP®, grupo control positivo MTA Angelus® y grupo control negativo IRM®, los cuales se incubaron en solución PBS durante 10 días, para posterior análisis por medio de MEB-EDS y Espectroscopía Raman. Los tres materiales a base de silicato de calcio analizados en este estudio demostraron ser bioactivos pues al entrar en contacto con una solución a base de fosfato desencadenaron la precipitación inicial de fosfato de calcio amorfo, que actúa como precursor durante la formación de apatita carbonatada.

ABSTRACT Calcium silicate-based materials have been shown to be bioactive due to their ability to produce biologically compatible carbonated apatite. The objective of this study was to analyze the bioactivity of Biodentine ™ and MTA Repair HP® in contact with human dentine discs, which were sealed and divided randomly to form four groups: group 1 Biodentine™, group 2 MTA Repair HP®, positive control group MTA Angelus® and negative control group IRM®, which were incubated in PBS solution for 10 days, for a subsequent analysis by means of MEB-EDS and Raman spectroscopy. The three calcium-based materials analyzed in this study proved to be bioactive because upon contact with a phosphate-based solution they were triggered at the onset of amorphous calcium phosphate, as the precursor during the formation of carbonated apatite.

ABSTRACT This work presents the experimental results of the study of the pericarp of unripe and ripe fruits of different varieties of habanero chili peppers (Capsicum chínense Jacq.) - Mayan Kisin, Mayan Ek and Mayan Kiin - using Raman spectroscopy. The unripe fruits of the three varieties were green, but they turned different colors at maturity: yellow (Mayan Kiin), orange (Mayan Ek) and red (Mayan Kisin). The Raman spectrum of the unripe fruit showed the presence of chlorophyll a and bacteriochlorophyll a, which are responsible for the green color observed during the immature stage. Raman spectra of ripe fruits revealed the presence of three widely dominant peaks at 1520, 1154 and 1006 cm-1 associated with the vibrations modes of the bonds C=C, C-C and C-CH3 (v1, v2 and v4, respectively) of carotenoids, which are primarily responsible for the color of fruits. In addition, it is also possible to see the harmonic peaks 2v1, 2v2 and 2v4, and the combinations v1+ v2, v2+ v4 and v1+ v4. The study of the pepper pericarp allowed identifying that the cuticle fruit originates C-H2 symmetric and asymmetric peaks at 2857 and 2908 cm1, respectively. This study suggests the Raman spectroscopic technique as a non-destructive, fast and useful tool to study the ripening process of habanero pepper.

RESUMEN En este trabajo se presentan los resultados experimentales del estudio del pericarpio de frutos inmaduros y maduros de chile habanero (Capsicum chínense Jacq.), de las variedades Mayan Kisin, Mayan Ek y Mayan Kiin, mediante la técnica de espectroscopia Raman. En su etapa inmadura, los frutos de las tres variedades presentaron un color verde, mientras que en su etapa madura los frutos fueron de color amarillo (Mayan Kiin), naranja (Mayan Ek), y rojo (Mayan Kisin). En el espectro Raman de los frutos inmaduros se observó dominio de las señales originadas por clorofila a y bacterioclorofila a, lo que es característico de su etapa inmadura y su color verde. En los espectros Raman de los frutos maduros se observaron tres picos ampliamente dominantes en 1520, 1154 y 1006 cm-1, asociados con los modos vibracionales de los enlaces C=C, C-C y C-CH3 (vi, v2 y v4, respectivamente) de los carotenoides, principales responsables del color. Además, es posible observar los picos de los armónicos 2v1, 2v2 y 2v4, y las combinaciones v1+ v2, v2+ v4 y v 1+ v4. Mediante un estudio transversal del pericarpio fue posible identificar que los picos en 2857 y 2908 cm-1 asociados a la vibración simétrica y antisimétrica de los enlaces C-H2, respectivamente, son originados por la cutina del fruto. Con este estudio se presenta a la técnica de espectroscópica Raman como un herramienta no destructiva, rápida y muy útil para el estudio del proceso de maduración del habanero.

Composites from polystyrene with hydroxyl end groups and multiwall carbon nanotubes were fabricated to evaluate their properties. The Carbon Nanotubes (CNTs) were synthetized by chemical vapor deposition technique using ferrocene and benzene as precursors. Polystyrene with hydroxyl end groups was prepared by solution polymerization employing styrene as monomer, 2-mercaptoethanol as chain transfer agent and AIBN as initiator. Thin films were obtained by two methods: pouring into petri dishes and dip-coating slides. CNTs were characterized to identify morphology and characteristic spectroscopic signals. The polystyrene with hydroxyl end groups and composites were analyzed by SEM, FTIR, Raman and UV-vis spectroscopies, Vickers microhardness and electrical resistivity. Raman analysis demonstrated chemical interactions between CNTs and polystyrene. Results showed that resistivity and transparency decreased by increasing CNTs concentrations in composites; transmittance was about 80% with 0.8 wt% content of nanotubes. The highest Vickers hardness registered value was at 1.6 wt% CNTs concentration.