Abstract In the present research, the synthesis of cobalt oxide Co3O4 was carried out using the sol-gel technique with subsequent heat treatment at 225 and 235 °C. The final product obtained was characterized by X-ray diffraction (XRD), showing a pure crystalline phase of Co3O4, cell parameters a=b=c=8.071 Å, and a volume of 525.7 Å3. The particle size was between 2.37 and 2.77 µm, which indicated that structural transformations from Co to Co3O4 induced an increase in the particle size. Through Rietveld refinement, the interatomic distances and inclination angles of the Co1, Co2, and Co3 polyhedra were analyzed in order to establish the structural behavior of cobalt oxide (II, III) at 235 °C. The UV-vis analysis allowed determining band gap (Eg) with values of 1.6 eV in the first region and 0.97 eV in the second. Scanning electron microscopy images showed that the particles agglomerated with increasing calcination temperature and exhibited larger particles. This work presents a detailed analysis of structural parameters of Co3O4 using the Vesta software with Rietveld refinement data.

Abstract New records of subtidal benthic marine algae from the State of Veracruz, the southern Gulf of Mexico, are presented, which include 7 species and 2 forms. The material was collected from 6 sampling forays at 4 locations between October 2013 and September 2017. The collection sites included the “Ana Elena” and “Riva Palacio” shipwrecks and some poorly explored reefs in the State of Veracruz, Mexico. The morphological characteristics of Hypoglossum simulans, Halymenia hancockii, Dictyota humifusa, Caulerpa sertularioides f. longiseta, Avrainvillea levis f. translucens, Udotea caribaea, U. dixonii, U. unistratea, and Anadyomene saldanhae are described. Information about the habitats and geographic distributions of these taxa is provided.

Resumen Se presentan nuevos registros de algas marinas bentónicas submareales del estado de Veracruz, sur del golfo de México, que incluyen 7 especies y 2 formas. El material fue recolectado en 6 muestreos de 4 localidades, entre octubre de 2013 y septiembre de 2017. Entre los sitios de recolección se encuentran los pecios “Ana Elena” y “Riva Palacio”, así como algunos arrecifes poco explorados en el estado de Veracruz, México. Se describen las características morfológicas de Hypoglossum simulans, Halymenia hancockii, Dictyota humifusa, Caulerpa sertularioides f. longiseta, Avrainvillea levis f. translucens, Udotea caribaea, U. dixonii, U. unistratea y Anadyomene saldanhae. Se proporciona información sobre los hábitats y la distribución geográfica de estos taxones.

In this work we investigate the vortex dynamics in a square mesoscopic superconducting cylinder in the presence of an applied magnetic field parallel to its axis. The rectangular cross-section of the sample is L² and an engineered columnar defect of area d² at the center is taken into account; L = 12ξ(0) for all simulations while d varies discretely from 1ξ(0) to 10ξ(0). We study the magnetization and the vortex configuration, increasing the magnetic field from zero to the normal state field. We found that for d > 7ξ(0) no vortices in the superconductor area are possible. Also, if the size of the defect is reduced, the nucleation fields decrease.