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Copyright of Boletin de Geologia is the property of Universidad Industrial de Santander and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the center-north of Venezuela is the Cordillera de la Costa, formed by the Serranía del Interior and the Serranía del Litoral in Venezuela, separated by the La Victoria Fault System. This research combines 2D structural restoration and thermokinematic modeling, apatite fission-track, seismological data and heat flow of the area, to reconstruct the deformation history and associate fault activity to the present-day seismicity. A map of Quaternary faults associated with thermal behavior and seismic activity was elaborated. The thermokinematic modeling allowing us predicting surface ages and time-temperature histories which were compared with data observed in the study zone. Our results suggest that the rocks were buried until the Eocene, when the Caribbean plate collides with the north central part of South America. We discriminated 4 tectonic cooling pulses: 48 to 40 Ma, 40 to 23 Ma, 23 to 5 and 5 to 0 Ma. The first one is related to the convergence between the Caribbean and South American plates, causing the emplacement of the Lara Nappes, the second one is related to the cooling of rocks caused during rocks transport to the surface product of the subduction of the Caribbean plate under the deformed Caribbean belt, the third one corresponds to the continuation of the subduction of the Caribbean plate under the South American plate, due to the reactivation of transpressive type faults and the last one relates to the advance of the Caribbean plate towards the east and the reactivation of important strike-slip faults. Despite the fact that there is an important seismic activity in the Caribbean mountains, in this sector of the Serranía del Interior there is not a significant distribution of earthquakes. [ABSTRACT FROM AUTHOR]

Using the novel flame aerosol pyrolysis method (FSP), a calcium phosphate bioglass was synthesized for the first time in the P2O5-CaO-Na2O. The samples obtained were characterized by X-ray diffraction(XRD) and diffuse reflectance infrared spectroscopy (DRIFTS), the latter serving to follow in-vitro biomineralization kinetics for 15 days in simulated body fluid (SBF). Using XRD, the amorphous nature of the bioglass was validated by exhibiting the whitlockite phase. The DRIFTS analysis revealed the characteristic bands of the phosphate groups in a range of about 500 to 1400 cm-1. Respectively, the evolution of the phosphate bands in the samples submerged in SBF indicate the formation of apatite, a process that followed a pseudo-first-order Lagergren kinetics. [ABSTRACT FROM AUTHOR]

Flotation of apatite contained in the tailings produced in the magnetic concentration process of the Pellet Plant of the Pacific Mining Company has been studied and analyzed. The mining activity annually produces millions of tons of tailings generated by the treatment of minerals, which are discharged in the form of pulp in dams. In recent years there have been several studies aimed to the recovering of valuable minerals contained in such tailings. For this reason, flotation tests were performed in a mini flotation column, where the following variables were analyzed: froth height, air flow, feed and wash water, with collector and frother dose constant at pH 9. It is concluded that it is possible to recover 75.3% of P2O5 contained in the tailings with a 21.8% grade in a single stage, using an air flow of 1.4 cm/s, washing water flow of 0.41 cm/s, feeding flow of 1.4 cm/s and froth height of 15 cm; using 400 g/t of collector, 400 g/t of dispersant and 10 g/t of frother agent. [ABSTRACT FROM AUTHOR]

Based on the statistical analysis results of the mechanical and curing tests of bone cements formulations added with Hydroxyapatite in percentages between 0 - 20 w/w and Dimethyl amino ethyl methacrylate (DMAEM) in percentages between 0 - 10 w/w reported in previous studies [1], four bone cements formulations were selected to evaluate the fixation of an apatite layer on its surface after immersion in a simulated biological fluid (FBS) for 15 and 30 days, and the tissue reaction through histological tests in rabbits tibias implanted with the material. According to the analysis by Scanning Electron Microscopy and Dispersive Energy Spectroscopy (SEM - EDS), the presence of hydroxyapatite and the co-monomer favored the fixation of a layer similar to biological apatite on the surface of the material after immersion for 15 and 30 days in the FBS; whereas, the formulations of unmodified bone cements showed no adhesion of the apatite layer after the same time of the immersion in the FBS. In general, the histological tests showed qualitatively and quantitatively that there was no inflammation reaction in the tissue when in contact with the modified or unmodified bone cement. [ABSTRACT FROM AUTHOR]

The main objective of the research is to evaluate the recovery of P2O5 in phosphoric rock through 3 models of froth flotation (direct, inverse and directinverse). Representative samples were taken from the department of Tolima and parameters were established for each of the flotations with a conditioning time of 5 minutes and flotation times between 7-10 minutes. Contact angle measurements were made with a value of 39° reflecting its hydrophilicity for the quartz case. According to Zeta potential measurements, a separation region between pH 2-5,8 was determined using anionic collectors for direct flotation and pH 5,8-10 using cationic collectors for reverse hydroxylapatite flotations. Finally, it was found that the direct-inverse flotation allowed a greater recovery of P2O5, using as oleic acid and Aero® 845 Promoter collectors in the anionic process, and the Aeromine® 3030C collector and the phosphoric acid depressant in the cationic process. [ABSTRACT FROM AUTHOR]

In this article is presented the design, construction, setting in operation and calibration of the Automated System for the Separation of Heavy Minerals (ASSHM). This equipment processes big volumes of rocks and silts with the purpose of accomplishing a primary mineral concentration that later will be refined and whose final grains of heavy minerals (apatite, zircon, sphene, among other) will be used under the External Detector Technique (EDT) for its dating by the Fission Tracks Dating Method (FTDM) used in the Thermochronology Laboratory of the UCV. This work is the result of an interdisciplinary effort between geologists, mathematicians, mechanical engineers and technicians in metallurgy. [ABSTRACT FROM AUTHOR]

Surface patterning process was carried out by oxidation of the surface of anodized Ti6Al4V by a 1M solution of H3PO4 at a constant voltage of 30 V and a variable current density for 60 seconds, followed by immersion in a solution of NaOH for 24 hours at 60°C, and a heat treatment at 450°C for one hour, where it formed a stable layer of dried sodium titanate and densified, which showed a low degree of crystallinity in the XRD analysis. Patterning was performed by incidence of a low intensity laser (1ìJ), characterizing the pattern size; with 90 minutes of exposed. The resistance of the particles was studied as well as the calcium ion absorptivity through the Electrochemical Impedance Spectroscopy technique (EIS). The bioactive character was evaluated by the simulated body fluid immersion at 37°C for 7 days, generating the Ti-OH- groups formed by the ions Na+ and H3O- exchange, which combined with the Ca+2 ions in the simulated body fluid SBF, forms amorphous calcium titanate which interacts with the phosphate ions. [ABSTRACT FROM AUTHOR]

Copyright of Boletin de Geologia is the property of Universidad Industrial de Santander and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, many researchers have focused their attention on processes that occur in living organisms because it is possible to reproduce in vitro. Based on this behavior, Tadashi Kokubo and colleagues developed a method for obtaining apatite coatings on bioactive surfaces from the immersion of the samples to be coated in a simulated body fluid. An update on the state of the art of this topic, emphasizing the composition of solutions and process parameters used during the treatment of titanium and their alloys is presented. As a result of the study it was possible to confirm that there is a tendency to increase the content of calcium and phosphate ions in solutions to accelerate of formation and subsequent growth of the coating. The use of these ion concentrations at levels that exceed 10 times as much as those presented by the simulated body fluid was reported. The inclusion of magnesium and hydrogen carbonate salts carriers and sodium chloride in the solutions can also affect positively the deposition speed of the coating and at the same time they can affect the crystallinity of the resulting apatite structures. High levels of hydrogen carbonate and magnesium ions in solutions generate amorphous structures in coatings. The parameters pH and temperature also have a significant influence on the deposition process helping to control the velocity of deposition process. [ABSTRACT FROM AUTHOR]

Copyright of Medicina Oral (16656024) is the property of Colegio Nacional de Cirujanos Dentistas Militares A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The results obtained in the preparation and micro-structural characterization of the calcium phosphate glasses coating on two different zirconia substrates are discussed. The thermal treatments were carried out at 1 100 °C for 2 h in air. The materials were characterized by scanning electron microscope (SEM), environment scanning electron microscope (ESEM), X-ray diffraction (XRD) and microanalysis by energy-dispersive-spectrometer (EDS) coupled to SEM. Also, the changes occurred at the material surfaces after two weeks in simulated body fluid (SBF) were studied. The observations by SEM showed a good deposition of the glass coatings on both zirconia substrates. The microanalysis results by EDS demonstrated the diffusion of magnesium from zirconia structure to glass for magnesia partially stabilized zirconia and the diffusion of calcium from glass to substrate for yttrium partially stabilized zirconia was also observed. The formation of new phases associated with crystallization of glass and the diffusion of calcium and magnesium provide a certain complexity to XRD patterns interpretations. After two weeks in SBF, the observations by ESEM and SEM revealed that significative changes at the surfaces of the materials were occurred. The changes were related with the glass degradation by effect of the SBF solution. No formation of apatite layer was observed. [ABSTRACT FROM AUTHOR]