Hydroxyapatite (HAp) and hydroxyapatite/multi-walled carbon nanotube (MWCNT) composites were obtained by the co-precipitation method, followed by ultrasound-assisted and microwave radiation and thermal treatment at 250 °C. X-ray diffraction (XRD) confirmed the presence of a hexagonal phase in all the samples, while Fourier-transform infrared (FTIR) spectroscopy elucidated the interaction between HAp and MWCNTs. The photoluminescent technique revealed that HAp and the composite with non-functionalized MWCNTs present a blue luminescence, while the composite with functionalized MWCNTs, under UV-vis radiation shows an intense white emission. These findings allowed presentation of a proposal for the use of HAp and HAp with functionalized MWCNTs as potential materials for optoelectronic and medical applications.

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Immature guava fruits (Psidium guajava L.) of commercial orchards in Mexico are affected by adults of Conotrachelus dimidiatus (Champion) causing economic losses to producers. The aim of this study was to assess the behavioral and electrophysiological responses of the weevil to selected semiochemicals emitted by the host plant fruit and to conspecifics. Volatile organic compounds isolated from host plant as β-caryophyllene, (S)-(−)-limonene, hexanal, and nonanal significantly attracted adults of both sexes in behavioral bioassays. Electroantennogram recordings showed largest responses to papayanal and grandlure III + IV released by C. dimidiatus and C. nenuphar, respectively. Our results indicate that behavioral and electroantennographic assays using synthetic compounds from host plant volatiles and insect volatile pheromones produce olfactometry and electroantennographic responses in C. dimidiatus. This is the first report of intraspecific chemical communication in this weevil. We discuss the significance of these responses for the natural behavior in guava orchards and their potential use in a pest management strategy.

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In this study, we measured the adsorption of Basic Blue 41 (BB41) dye on a maize cob adsorbent and on two model adsorbents (cellulose triacetate and cellulose acetate propionate). The experimental adsorption data were evaluated with the isotherm equations of Langmuir, Freundlich, Langmuir-Freundlich and Dubinin-Radushkevich, and constants were obtained exclusively by non-linear regression. In order to select the optimal isotherm equation, Akaike information criterion was used. The celluloses obeyed the Langmuir isotherm in the temperature range tested, whereas the corncob followed the Freundlich equation. This comparative study shows that limited amounts of the cationic dye were adsorbed on the model celluloses than on the cob. BB41 was neither adsorbed horizontally nor vertically onto the cob, whereas it competed with water molecules and despite saturation, did not exhaustively occupy the surface of the celluloses. The Gibbs free energy of adsorption was evaluated using the equilibrium constants obtained by several procedures and the results were found to be inconsistent.

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