Strawberries are highly consumed around the world; however, the post-harvest shelf life is a market challenge to mitigate. It is necessary to guarantee the taste, color, and nutritional value of the fruit for a prolonged period of time. In this work, a nanocoating based on chitosan and ZnO nanoparticles for the preservation of strawberries was developed and examined. The chitosan was obtained from residual shrimp skeletons using the chemical method, and the ZnO nanoparticles were synthesized by the close-spaced sublimation method. X-ray diffraction, scanning electron microscopy, electron dispersion analysis, transmission electron microscopy, and infrared spectroscopy were used to characterize the hybrid coating. The spaghetti-like ZnO nanoparticles presented the typical wurtzite structure, which was uniformly distributed into the chitosan matrix, as observed by the elemental mapping. Measurements of color, texture, pH, titratable acidity, humidity content, and microbiological tests were performed for the strawberries coated with the Chitosan/ZnO hybrid coating, which was uniformly impregnated on the strawberries’ surface. After eight days of storage, the fruit maintained a fresh appearance. The microbial load was reduced because of the synergistic effect between chitosan and ZnO nanoparticles. Global results confirm that coated strawberries are suitable for human consumption.

High-porosity nanostructured amorphous tungsten OXIDE (a-WO₃) films were synthesized by a Hot Filament Chemical Vapor Deposition technique (HFCVD) and then transformed into a crystalline WO₃ by simple thermal annealing. The a-WO₃ films were annealed at 100, 300, and 500 °C for 10 min in an air environment. The films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-Raman spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and UV–vis spectroscopy. Results revealed that the a-WO₃ films were highly porous, composed of cauliflower-like structures made of nanoparticles with average sizes of 12 nm. It was shown that the effect of annealing on the morphology of the a-WO₃ films leads to a sintering process. However, the morphology is conserved. It was found that at annealing temperatures of 100 °C, the a-WO₃ films are of an amorphous nature, while at 300 °C, the films crystallize in the monoclinic phase of WO₃. The calculated bandgap for the a-WO₃ was 3.09 eV, and 2.53 eV for the film annealed at 500 °C. Finally, the results show that porous WO₃ films preserve the morphology and maintain the porosity, even after the annealing at 500 °C.

A comparative study on the sensing properties of a tapered optical fiber pristine and functionalized with the palladium nanoparticles to hydrogen and volatile organic compounds (VOCs), is presented. The sensor response and, response/recovery times were extracted from the measurements of the transient response of the device. The tapered optical fiber sensor was fabricated using a single-mode optical fiber by the flame-brushing technique. Functionalization of the optical fiber was performed using an aqueous solution of palladium chloride by drop-casting technique assisted for laser radiation. The detection principle of the sensor is based on the changes in the optical properties of palladium nanoparticles when exposed to reducing gases, which causes a variation in the absorption of evanescent waves. A continuous wave laser diode operating at 1550 nm is used for the sensor characterization. The sensor functionalized with palladium nanoparticles by this technique is viable for the sensing of hydrogen and VOCs, since it shows an enhancement in sensor response and response time compared to the sensor based on the pristine optical microfiber. The results show that the fabricated sensor is competitive with other fiber optic sensors functionalized with palladium nanoparticles to the hydrogen.

In this work, a novel route is discussed to produce in one step ZnO/Burkeite powders by the modified solution combustion method. The ZnO particles enhance the photocatalytic activity in the degradation of Rhodamine B, in which Burkeite mineral acts as a support due to the pH-dependent morphology of the particle aggregates of the as-synthesized powders. The X-ray diffraction (XRD) characterization shows the presence of a heterostructure: ZnO/Burkeite. The Scanning Electron Microscopy (SEM) image shows a morphological dependence with the pH of the solution used for the synthesis. The results show that the system with the highest degradation (92.4%) corresponds to the case in which ZnO/Burkeite heterostructure was synthesized with a pH 11.

The n-dimensional unit hypercubes, Qn (n = 1 to 4), are used as n-dimensional graphs (Stereoisograms) to describe the stereoisomeric (enantiomeric and/or diastereomeric) relationships of molecules containing one to four RS-stereogenic centers. To achieve this goal, the strings of 0’s and 1’s, used for labelling the vertices of unit hypercubes, are substituted by strings of R’s and S’s-descriptors coming from the CIP priority rules. The development of those ndimensional unit hypercubes along ordered axes and the application of combinatorial techniques allow to locate the enantiomeric pairs at antipodal vertices (points related by a chirality center, which satisfies the bitwise operation known as “NOT”); whereas diastereomers are related by mirror planes, whose reflection results in a partial permutation of the RS-descriptors. These facts are in good agreement with the literature and the principles of the combinatorial theory applied to such hypercubes. On the other hand, because the maximum number of stereoisomers 2n is not always held, “pseudo hypercubes” containing one or more “ghost vertices” are proposed to include the meso (achiral) stereoisomers

Los nanomateriales han dado un giro a la industria textil, mejorando las propiedades de los tejidos funcionales, añadiendo distintos materiales para mejorar la durabilidad, repelencia al agua, autolimpieza, antibacteriano, protección UV, entre otros. En particular, las características antibacterianas han sido de interés en textiles para ropa médica y deportiva. Se ha descubierto que la combinación plata-zeolita tiene un efecto biocida, que está relacionado con el estado de oxidación de las especies de plata y el tamaño de las partículas, dichas propiedades biocidas ayudan a la inhibición de Staphylococcus aureus, Escherichia coli (E. coli) y Candida albicans (C. albicans). En este trabajo, se estudió el efecto inhibidor de la proliferación de Escherichia coli (E. coli) a diferentes concentraciones de zeolita intercambiadora de plata sobre un sustrato de algodón. La zeolita de intercambio iónico Ag+ se caracterizó mediante microscopía electrónica de barrido (MEB) y difracción de rayos X (DRX); además, se evaluó la eficiencia antibacteriana en el tejido mediante el Método Kirby-Bauer. De acuerdo con los resultados, se aprecia que el material desarrollado a base de zeolita Ag+ tiene el efecto antimicrobiano, toda vez que después de 24 horas de cultivo de la bacteria E. coli sobre el textil, no se aprecia la presencia de dichas bacterias.