Influence of hydrogen peroxide in the tribocorrosion behaviour of a CoCrMo biomedical alloy

This paper studies the influence of hydrogen peroxide (H2O2) in simulated body fluids on the wear and corrosion behaviour of a CoCrMo biomedical alloy. CoCrMo are passive materials commonly used in prosthesis and implants because of its high corrosion resistance and mechanical properties. Hydrogen peroxide is produced by bacteria and leukocytes as a consequence of an inflammatory reaction which may modify the tribo-electrochemical response of metals implanted in the human body. Indeed, the oxidizing environment generated by the presence of the peroxide increases the metal dissolution rate. Electrochemical and tribocorrosion tests were carried out in a PBS solution with different addition of H2O2 (0.5, 2, 4 and 12%).The authors acknowledge Generalitat Valencia for the Gerónimo Forteza financial support and to the Electron Microscopy Service of the UPV for the SEM images

Tribocorrosion behavior of beta titanium biomedical alloys in phosphate buffer saline solution

[EN] The tribo-electrochemical behavior of different β titanium alloys for biomedical applications sintered by powder metallurgy has been investigated. Different mechanical, electrochemical and optical techniques were used to study the influence of the chemical composition, Sn content, and the electrochemical conditions on the tribocorrosion behavior of those alloys Ti30NbxSn alloys (where x is the weight percentage of Sn content, 2% and 4%). Sn content increases the active and passive dissolution rate of the titanium alloys, thus increasing the mechanically activated corrosion under tribocorrosion conditions. It also increases the mechanical wear of the alloy. Prevailing electrochemical conditions between 1 and 2 V influences the wear accelerated corrosion by increasing it with the applied potential and slightly increases the mechanical wear of Ti30Nb4Sn. Wear accelerated corrosion can be predicted by existing models as a function of electrochemical and mechanical parameters of the titanium alloys.The authors would like to thank the Ministerio de Ciencia e Innovacion of the Spanish government for the financial support under the project MAT2011-22481.Guiñón Pina, V.; Dalmau, A.; Devesa, F.; Amigó Borrás, V.; Igual Muñoz, AN. (2015). Tribocorrosion behavior of beta titanium biomedical alloys in phosphate buffer saline solution. Journal of the Mechanical Behavior of Biomedical Materials. 46:59-68. https://doi.org/10.1016/j.jmbbm.2015.02.016S59684

Electrochemical behavior of near-beta titanium biomedical alloys in phosphate buffer saline solution

The electrochemical behavior of three different near-β titanium alloys (composed by Ti, Nb and Sn) obtained by powder metallurgy for biomedical applications has been investigated. Different electrochemical and microscopy techniques were used to study the influence of the chemical composition (Sn content) and the applied potential on themicrostructure and the corrosion mechanisms of those titaniumalloys. The addition of Sn below4wt.% to the titanium powder improves the microstructural homogeneity and generates an alloy with high corrosion resistancewith lowelasticmodulus, beingmore suitable as a biomaterial.When the Sn content is above 4%, the corrosion resistance considerably decreases by increasing the passive dissolution rate; this effect is enhanced with the applied potential.The authors would like to thank the Ministerio de Ciencia e Innovacion of the Spanish Government for the financial support under the project MAT2011-22481.Dalmau Borrás, A.; Guiñón Pina, V.; Devesa Albeza, F.; Amigó Borrás, V.; Igual Muñoz, AN. (2015). Electrochemical behavior of near-beta titanium biomedical alloys in phosphate buffer saline solution. Materials Science and Engineering: C. 48:55-62. https://doi.org/10.1016/j.msec.2014.11.036S55624

Passivation behaviour of Alloy 31 (UNS N08031) in polluted phosphoric acid at different temperatures

The influence of temperature (20–80 °C) and chloride concentration (0.06–0.42 wt.% KCl) on the electrochemical behaviour of the UNS N08031 was studied in 40 wt.% polluted phosphoric acid solution. Passivation behaviour was investigated by using potentiostatic tests at different potentials. From the linear regions of the log i vs. log t transients, the parameter n was obtained. The results showed that the applied potential hardly affects on the passivation rate n. However, n values decreased when temperature increased. The values of n demonstrated that the passive film formed on Alloy 31 was compact and highly protective.The authors express their gratitude to the MAEC of Spain (PCI Mediterraneo C/8196/07, C/018046/08, D/023608/09 and D/030177/10), to Programa de Apoyo a la Investigacion y Desarrollo de la UPV (PAID-06-09) and to the Generalitat Valenciana (GV/2011/093) for the financial support and to Dr. Asuncion Jaime for her translation assistance.Escrivá Cerdán, C.; Blasco Tamarit, ME.; García García, DM.; García Antón, J.; Guenbour, A. (2012). Passivation behaviour of Alloy 31 (UNS N08031) in polluted phosphoric acid at different temperatures. Corrosion Science. 56:114-122. https://doi.org/10.1016/j.corsci.2011.11.014S1141225

The Transcriptome Analysis of Strongyloides stercoralis L3i Larvae Reveals Targets for Intervention in a Neglected Disease

BackgroundStrongyloidiasis is one of the most neglected diseases distributed worldwide with endemic areas in developed countries, where chronic infections are life threatening. Despite its impact, very little is known about the molecular biology of the parasite involved and its interplay with its hosts. Next generation sequencing technologies now provide unique opportunities to rapidly address these questions.Principal FindingsHere we present the first transcriptome of the third larval stage of S. stercoralis using 454 sequencing coupled with semi-automated bioinformatic analyses. 253,266 raw sequence reads were assembled into 11,250 contiguous sequences, most of which were novel. 8037 putative proteins were characterized based on homology, gene ontology and/or biochemical pathways. Comparison of the transcriptome of S. strongyloides with those of other nematodes, including S. ratti, revealed similarities in transcription of molecules inferred to have key roles in parasite-host interactions. Enzymatic proteins, like kinases and proteases, were abundant. 1213 putative excretory/secretory proteins were compiled using a new pipeline which included non-classical secretory proteins. Potential drug targets were also identified.ConclusionsOverall, the present dataset should provide a solid foundation for future fundamental genomic, proteomic and metabolomic explorations of S. stercoralis, as well as a basis for applied outcomes, such as the development of novel methods of intervention against this neglected parasite

Modifiable risk factors associated with prediabetes in men and women: A cross-sectional analysis of the cohort study in primary health care on the evolution of patients with prediabetes

Background: Prediabetes is a high-risk state for diabetes development, but little is known about the factors associated with this state. The aim of the study was to identify modifiable risk factors associated with the presence of prediabetes in men and women. Methods: Cohort Study in Primary Health Care on the Evolution of Patients with Prediabetes (PREDAPS-Study) is a prospective study on a cohort of 1184 subjects with prediabetes and another cohort of 838 subjects without glucose metabolism disorders. It is being conducted by 125 general practitioners in Spain. Data for this analysis were collected during the baseline stage in 2012. The modifiable risk factors included were: smoking habit, alcohol consumption, low physical activity, inadequate diet, hypertension, dyslipidemia, and obesity. To assess independent association between each factor and prediabetes, odds ratios (ORs) were estimated using logistic regression models. Results: Abdominal obesity, low plasma levels of high-density lipoprotein cholesterol (HDL-cholesterol), and hypertension were independently associated with the presence of prediabetes in both men and women. After adjusting for all factors, the respective ORs (95% Confidence Intervals) were 1.98 (1.41-2.79), 1.88 (1.23-2.88) and 1.86 (1.39-2.51) for men, and 1.89 (1.36-2.62), 1.58 (1.12-2.23) and 1.44 (1.07-1.92) for women. Also, general obesity was a risk factor in both sexes but did not reach statistical significance among men, after adjusting for all factors. Risky alcohol consumption was a risk factor for prediabetes in men, OR 1.49 (1.00-2.24). Conclusions: Obesity, low HDL-cholesterol levels, and hypertension were modifiable risk factors independently related to the presence of prediabetes in both sexes. The magnitudes of the associations were stronger for men than women. Abdominal obesity in both men and women displayed the strongest association with prediabetes. The findings suggest that there are some differences between men and women, which should be taken into account when implementing specific recommendations to prevent or delay the onset of diabetes in adult population

Methods for Calibrating the Electrochemical Quartz Crystal Microbalance: Frequency to Mass and Compensation for Viscous Load

The main output from an Electrochemical Quartz Crystal Microbalance is a frequency shift. This note describes how to separate the mass- and viscous load contributions to this shift by a calibration procedure. The mass calibration is made by electroplating from a copper sulfate solution in ethanol/water with 100% current efficiency. An estimate of viscous load is obtained by measuring the energy dissipation and is related to frequency change using the Kanazawa–Gordon equation. Two approaches are discussed: either by performing calibration experiments in a series of water–glycerol mixtures or by following oscillations in frequency and dissipation by collecting data during the stabilization phase of the experiment

Effect of Bactericidal Elements Addition on the Microstructure and Mechanical Properties of Ti34Nb Alloy

[EN] The functionalization of ß-Ti alloys by the addition of small amounts of bactericidal elements is interesting for biomedical applications. Thus, alloying pure titanium with highly biocompatible elements such as Nb or Ta, stabilizes the ß phase of the resulting alloy although they can also include difficulties during the fabrication process due to their refractory nature. This work studies the effect of small additions of Ag and Cu (1.5 to 3 wt.%) on the microstructure and mechanical properties of the Ti34Nb (wt.%) alloy processed by powder metallurgy. The blend elemental powders were mixed (30 rpm during 30 min). The samples were compacted at 600 MPa and sintered at 1250 ºC during 3 hours. The microstructure was analyzed by X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscope with X-Ray Spectroscopy (FESEM/ EDS). The mechanical properties were obtained by bending tests; the elastic modulus was measured by ultrasonic methods and the porosity by Archimedes test. Cu addition generates the appearance of ¿ phase sheets inside the ß phase grains. Cu also decreases the open porosity and increases the closed porosity of the material. On the contrary, Ag addition does not influence the stabilization of the ß phase and it does not modify the density, thus the total porosity of the resulting material. With respect to the influence of the alloying elements on the elastic modulus (E) of the alloys, the E of the Ti34Nb (76.8 GPa) increases with the Cu addition (92.6 GPa) and decreases with the Ag one (68.9 GPa). Therefore, silver addition, which does not modify the microstructure and slightly decrease the mechanical properties of the Ti34Nb, can be considered a good alloying element to provide antibacterial features to the titanium alloy without losing performance.The authors would like to thank the Ministry of Economy and Competitiveness for the financial under the Research Project MAT2014-53764-C3-1-R and MAT2014-53764-C3-3-R. Universitat Politècnica de València for the financial support by Researcher Training Program with the predoctoral contract dated in 28 february of 2014, European Comision due to FEDER founds to acquire investigation equipment and the Electron Microscopy Service of the Universitat Politècnica de Valencia.Gil, E.; Amigó Mata, A.; Igual Muñoz, AN.; Amigó, V. (2017). Effect of Bactericidal Elements Addition on the Microstructure and Mechanical Properties of Ti34Nb Alloy. Materials Science Forum. 899:185-190. doi:10.4028/www.scientific.net/MSF.899.185S18519089