Photocatalytic degradation of methylene blue by graphene decorated titanium dioxide (TiO₂) powders heated at different temperatures was analyzed. The powders were prepared by mixing TiO₂ with graphene prepared by the modified Hummers method. A thermal treatment was applied to mixed and pure TiO₂ powders with the aim of analyze their structural dependence on temperature, and consistently their photocatalytic degradation effect on methylene blue solutions exposed to UV and visible radiation. Structural characterization of the powders was carried out by x-ray diffraction and Raman spectroscopy. When irradiated with UV, the mixed powders showed as high as 87% photocatalytic degradation, while the pure TiO₂ reached values of 59%. For visible radiation, as it is expected, the pure TiO₂ showed no activity, while the mixture presented degradation of 40%.

BiOI nanostructures were synthetized through a hydrothermal process using either bismuth acetate or subsalicylate as Bi precursor. Regardless of the used Bi source, the same crystalline structure of BiOI was obtained; nevertheless, the nature of the Bi precursor had an evident impact in the color appearance of the obtained sample. Another notable difference was observed in the resulting morphology, where ∼1.6 μm flower- and dandelion-like shapes were obtained for acetate and subsalicylate, respectively; both structures assembled by around 30 nm thick nanoflakes with rounded and straight edge, respectively. UV–vis diffuse reflectance shows an energy gap around 1.8 eV. Raman spectroscopy confirms also the tetragonal phase of BiOI. The photocatalytic activity was evaluated through degradation of methyl orange dye using visible and UV light sources, comparing results with P25 TiO₂. Both BiOI nanostructures presented an improvement of photocatalytic activity when irradiated with visible light, having the best photoactivity the sample synthetized with bismuth acetate.

CdTe:Sn thin films were grown by pulsed laser deposition on glass substrates at room temperature. The study of the changes in the chemical, structural and optical properties of the films as a function of the density of Sn ions calculated from Langmuir planar probe measurments is presented. Four films were grown by the simultaneous ablation of CdTe and Sn targets in vacuum. The Sn ion density was modified by varying the fluence on the Sn target, while the CdTe plasma density was kept constant for all the deposits. One CdTe film was grown as control sample using the same experimental conditions as in the CdTe:Sn films. The chemical composition was analyzed by XPS, where a dependence of the Sn incorporation into the CdTe lattice, on the Sn ion plasma density was demonstrated. The crystalline structure analysis by XRD showed a hexagonal structure for all the films. When the CdTe and Sn plasmas were combined, a preferential orientation in the plane (110) was observed for the resulting films. Furthermore, as Sn plasma density increased, the intensity of the (110) peak increased as well, suggesting that crystalline re-orientation is an effect of Sn incorporated into the CdTe lattice. Vibrational behavior was analyzed by Raman spectroscopy. A vibrational mode appeared at 118 cm⁻¹ and was related to a Sn-Te vibration, suggesting the incorporation of substitutional Sn into the CdTe lattice. The Sn-Te bonding was confirmed by XPS by the appearance of signals centered at 485 and 494 eV, which correspond to Sn²⁺ in SnTe. Thin films thicknesses values were between 320 and 460 nm increasing with Sn ion density. The band gap calculated using UV–vis spectrophotometry, resulted in values ranging from 1.42 to 1.46 eV. PL measurements showed a slight blue shift of the near-edge emission as Sn plasma density increased.

<!--Galleys --> <!--Full Text:--> PDF <!--END GALLEYS---> Abstract Among Bagre genera, there is a high variation in the estimation of age, a concern due to overexploitation risk in fisheries because of age underestimation. Bagre panamensis is an important fishery resource of the Mexican Pacific and the Gulf of California. Its age is known from otoliths, but its accuracy needs to be confirmed, and the periodicity of the otoliths record validated. The external morphology, some microstructure attributes, and age record of B. panamensis' otoliths were described from 371 specimens collected southeast of the Gulf of California. The lapilli otoliths were larger than the sagittae and asterisci otoliths. The lapilli otoliths present aragonite crystals with a prismatic shape, and their growth is radial, from the core to the otolith edge. The lapilli otoliths form an annual growth ring, defined by the slowdown in the growth that occurs during April to July, during the breeding season. The ages of the individuals ranged from 1 to 15 years, and the applied method is considered adequate and accurate for its estimation (otolith cross-sectioning and red-neutral staining).

In this work, structural, optical and electrical properties of ZnO thin films grown by laser ablation of a Zn metallic target on oxygen atmosphere using the 532 nm emission of the second harmonic of a Nd:YAG laser, are studied. Different mean kinetic energies of the plasma (E_k) at fixed ion density (N_p) were used as control parameters. X-ray diffraction profiles show the presence of a width (002) peak together with a peak associated with the (101) reflection. Changes in E_k affect the crystallinity of the samples. An intense PL emission in the visible range of the spectra associated with a majority intrinsic donor defects can be observed. The films showed an unusual low electrical resistivity as compared to the commonly reported values for undoped ZnO thin films.

Amoebiasis, a disease caused by the protozoan Entamoeba histolytica, represents a serious public health problem, mainly in developing countries. The first line of therapy for amoebiasis treatment is metronidazole (MTZ); however, clinical isolates of E. histolytica with resistance to MTZ and varying sensitivity to other antiamoebic drugs threaten the effectiveness of the prevention and treatment of this parasitic infection. Natural products stand out as a promising strategy to develop new, safe and more effective alternatives. In this study, we determined and compared the phytochemical profiles of Agave tequilana, Agave angustifolia, Agave rhodacantha, and Agave maximiliana and described their cytotoxic effect on E. histolytica trophozoites. The results show that the four Agaves kill E. histolytica in a species–time–dose-dependent manner. A morphologic analysis of the treated parasites showed evident morphological alterations suggestive of programmed cell death with nuclear alterations; it also highlighted the presence of rounded cells with protuberances/perforations in the membrane and cells that appeared to have exploded. The overall activity of Agave ethanolic extracts in E. histolytica can help provide new strategies to advance alternative treatments against amoebiasis.