Surface characteristics can mediate biological interaction improving or affecting the tissue integration after implantation of a biomaterial. Features such as topography, wettability, surface energy and chemistry can be key determinants for interactions between cells and materials. Plasma electrolytic oxidation (PEO) is a technique used to control this kind of parameters by the addition of chemical species and the production of different morphologies on the surfaces of titanium and its alloys. With the purpose to improve the biological response, surfaces of c.p titanium and Ti6Al4V were modified by using PEO. Different electrolytes, voltages, current densities and anodizing times were tested in order to obtain surfaces with different characteristics. The obtained materials were characterized by different techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and glow discharge optical emission spectroscopy (GDOES). Wettability of the obtained surfaces were measured and the corresponding surface energies were calculated. Superhydrophilic surfaces with contact angles of about 0 degrees were obtained without any other treatment but PEO and this condition in some cases remains stable after several weeks of anodizing; crystal phase composition (anatase-rutile) of the anodic surface appears to be critical for obtaining this property. Finally, in order to verify the biological effect of these surfaces, osteoblast were seeded on the samples. It was found that cell behavior improves as SFE (surface free energy) and coating porosity increases whereas it is affected negatively by roughness. Techniques for surface modification allow changes in the coatings such as surface energy, roughness and porosity. As a consequence of this, biological response can be altered. In this paper, surfaces of c.p Ti and Ti6Al4V were modified by using plasma electrolytic oxidation (PEO) in order to accelerate the cell adhesion process.

Nanotubular structures were generated on the surface of titanium c.p. by anodization technique in an aqueous solution of acetic acid (14% v/v) with different sources of fluoride ion (HF, NaF, NH F). The aim of using these three different compounds is to study the effect of the counterion (H , Na and NH4+) on the morphology, wettability and surface free energy of the modified surface. Nanotubes were generated at 10 and 15 V for each anodizing solution. To further improve surface characteristics, the samples were heat-treated at 600°C for 4 h and at 560°C for 3 h. SEM images revealed the formation of nanotubes in all anodizing conditions, while their diameter increased proportionally to the electric potential. X-ray diffraction and micro-Raman spectroscopy results showed the presence of both anatase and rutile phases, with a higher content of rutile in the coatings obtained using NH F and an applied potential of 10 V. The heat-treatment significantly increased the wettability of the anodic coatings, especially for the coating obtained at 15 V with HF, which showed values < 7 degrees of contact angle. Besides, the nanotubes show a decrease in diameter due to the heat treatment, except for the nanotubes formed in NH F. Depending on their surface properties (e.g. low contact angle and high surface free energy), these coatings potentially have great potential in biomedical applications, sensors devices, and catalytic applications among others. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1341-1354, 2018.

Una evaluación petrofísica se llevó a cabo para los niveles siliciclásticos del pozo ANH-TIERRALTA-2-X-P en la Cuenca de Sinú-San Jacinto, Noroeste de Colombia. El pozo se dividió en cinco unidades informales que contienen diez ciclos estratigráficos basándose en la litología y la respuesta del registro de gamma ray. La primera desde la superficie hasta 1100 ft (Formación El Carmen, Oligoceno), la segunda (1100 ft - 3100 ft) compuesta de biomicritas (Formación Tolúviejo, Eoceno). La Unidad 3 corresponde a areniscas cuarzosas y litoarenitas interestratificadas con lutitas (de 2000 ft de espesor); la Unidad 4 corresponde a areniscas conglomeráticas (5530 ft – 6620 ft); la Unidad 5 (6620 ft hasta 6770 ft) contiene calizas grises; estas tres últimas, se correlacionan con la Formación San Cayetano, Paleoceno. La unidad basal (6770 ft hasta 8711 ft) contiene lutitas de color gris oscuro, y se correlaciona con la Formación Cansona, del Cretácico superior. Petrográficamente, se analizaron 26 secciones delgadas del Ciclo 8 (Unidad 3). La diagénesis temprana está representada por compactación, caolinitización de feldespatos alcalinos y sericitización de plagioclasas, y la diagénesis de enterramiento por neoformación de cemento de poros de calcita. Los ciclos siliciclásticos basales (4, 5 y 6 en la Unidad 4) son los más prospectivos para la acumulación de hidrocarburos, mientras que el Ciclo 7 (en la Unidad 3), correspondería a la roca sello del posible sistema petrolífero. El volumen de shale se calculó a partir de los registros de gamma ray y densidad-neutrón. Los cálculos de porosidad hechos a partir del registro de densidad (entre 8 y 15%) son los más próximos a los valores calculados en el laboratorio a partir de los plugs recuperados (5%). La saturación de agua se estimó utilizando la porosidad calculada y el registro de resistividad profunda, reportándose un valor promedio de 95% en los potenciales reservorios analizados

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