Metal–metal oxide (MMO), graphite and laboratory-made Ag/AgCl electrodes were electrochemically characterized to be used as reference electrodes embedded in concrete structures. Electrodes were ...studied in both, aqueous solutions of pH ranging from 7 to 13.5 and embedded into cement mortars; and the electrochemical studies were carried out in the absence and presence of chloride ions. Potential evolution, polarization behaviour, galvanostatic pulse response and impedance characteristics of the electrodes were carried out in aqueous solutions. Besides, the electrochemical stability of the electrodes embedded in mortar was studied for an exposure period of 2 years. It was found that the MMO pseudo-reference electrode is pH-sensitive, the graphite pseudo-reference electrode is oxygen sensitive and the Ag/AgCl pseudo-reference electrode is chloride sensitive. In spite of the fact that any of them can be used to determine the corrosion rates of rebars because they do not depend on the absolute potential and/or the long-term stability of the reference electrode when using traditional electrochemical techniques, long-term drifts in the electrode potentials may lead to misinterpretations of the rebar state. In this context graphite electrodes are recommended because they provide conservative results regarding the active/passive state of the rebars.
Nanotechnology is constantly advancing in dental science, progressing several features aimed at improving dental implants. An alternative for surface treatment of dental implants is electrochemical ...anodization, which may generate a nanotubular surface (TiO2 nanotubes) with antibacterial potential and osteoinductive features. This systematic review and meta-analysis aims to elucidate the possible antibacterial properties of the surface in question compared to the untreated titanium surface.
For that purpose, was performed a systematic search on the bases PubMed, Lilacs, Embase, Web Of Science, Cinahl, and Cochrane Central, as well as, manual searches and gray literature.
The searches resulted in 742 articles, of which 156 followed for full-text reading. Then, 37 were included in the systematic review and 8 were included in meta-analysis.
Fifteen studies revealed significant antibacterial protection using TiO2 nanotube surfaces, while 15 studies found no statistical difference between control and nanotextured surfaces. Meta-analysis of in vitro studies demonstrated relevant bacterial reduction only for studies investigating Staphylococcus aureus in a period of 6 h. Meta-analysis of in vivo studies revealed three times lower bacterial adhesion and proliferation on TiO2 nanotube surfaces.
TiO2 nanotube topography as a surface for dental implants in preclinical research has demonstrated a positive relationship with antibacterial properties, nevertheless, factors such as anodization protocols, bacteria strains, and mono-culture methods should be taken into consideration, consequently, further studies are necessary to promote clinical translatability.
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•TiO2 nanotubes as an implant surface topography was systematically revised according to their antibacterial potential.•Nanotubular surfaces revealed to induce antibacterial responses.•Preclinical research showed favorable antibacterial outcomes for TiO2 nanotubes compared to untreated Ti.•Further research is needed to design complex studies evaluating TiO2 nanotube surfaces in clinical set.
Several experimental techniques were used to characterise steel rebars embedded in concrete for 70
years and exposed to mountain weather conditions in a sulphur-containing environment. The research ...has the objective of understanding the stages of rusting of steel in concrete in a non-conventional environment. Such understanding would provide information concerning the nature of the corrosion products formed on the steel rebars in order to make accurate predictions by means of analytical models.
Papillary thyroid carcinoma (PTC), the most frequent thyroid cancer, is characterized by low proliferation but no apoptosis, presenting frequent lymph-node metastasis. Papillary thyroid carcinoma ...overexpress transforming growth factor-beta (TGF-β). In human cells, TGF-β has two opposing actions: antitumoral through pro-apoptotic and cytostatic activities, and pro-tumoral promoting growth and metastasis. The switch converting TGF-β from a tumor-suppressor to tumor-promoter has not been identified. In the current study, we have quantified a parallel upregulation of TGF-β and nuclear p27, a CDK2 inhibitor, in samples from PTC. We established primary cultures from follicular epithelium in human homeostatic conditions (h7H medium). TGF-β-dependent cytostasis occurred in normal and cancer cells through p15/CDKN2B induction. However, TGF-β induced apoptosis in normal and benign but not in carcinoma cultures. In normal thyroid cells, TGF-β/SMAD repressed the p27/CDKN1B gene, activating CDK2-dependent SMAD3 phosphorylation to induce p50 NFκB-dependent BAX upregulation and apoptosis. In thyroid cancer cells, oncogene activation prevented TGF-β/SMAD-dependent p27 repression, and CDK2/SMAD3 phosphorylation, leading to p65 NFκB upregulation which repressed BAX, induced cyclin D1 and promoted TGF-β-dependent growth. In PTC samples from patients, upregulation of TGF-β, p27, p65 and cyclin D1 mRNA were significantly correlated, while the expression of the isoform BAX-β, exclusively transcribed in apoptotic cells, was negatively correlated. Additionally, combined ERK and p65 NFκB inhibitors reduced p27 expression and potentiated apoptosis in thyroid cancer cells while not affecting survival in normal thyroid cells. Our results therefore suggest that the oncoprotein p27 reorganizes the effects of TGF-β in thyroid cancer, explaining the slow proliferation but lack of apoptosis and metastatic behavior of PTC.
•There are no works related to the corrosion of drums containing radioactive waste.•Chloride induces high corrosion rate and after 1year it drops abruptly.•Decrease in the corrosion rate is due to ...the lack of water to sustain the process.•Cementated ion-exchange resins do not pose risks of corrosion of the steel drums.
Exhausted ion-exchange resins used in nuclear reactors are immobilized by cementation before being stored. They are contained in steel drums that may undergo internal corrosion depending on the presence of certain contaminants. The objective of this work is to evaluate the corrosion susceptibility of steel drums in contact with cemented ion-exchange resins with different aggressive species. The corrosion potential and the corrosion rate of the steel, and the electrical resistivity of the matrix were monitored for 900days. Results show that the cementation of ion-exchange resins seems not to pose special risks regarding the corrosion of the steel drums.
The electrochemical behaviour of pure Zn and galvanized steel in solutions simulating the pore solution of carbonated concrete has been studied by means of potentiodynamic polarization tests and ...polarization resistance measurements. Pure Zn was chosen because it simulates well the behaviour of galvanized steel, yielding more reproducible results. The effect of different degrees of carbonation and the presence of different chloride contents in the simulated pore solutions was investigated. Results show that at a given pH (about 9.5) the corrosion susceptibility of Zn depends on anions concentration (carbonate and bicarbonate). The results obtained in simulated carbonated concrete pore solutions show that with low anion concentration Zn does not passivate while in presence of high levels of carbonate and bicarbonate the corrosion resistance is improved. Besides, the presence of chloride increases the corrosion susceptibility.
Objectives: The implementation of new health services is a complex process. This study investigated the first phase of the adaptive implementation of the Dutch Meeting Centres Support Programme ...(MCSP) for people with dementia and their carers in three European countries (Italy, Poland, the UK) within the JPND-MEETINGDEM project. Anticipated and experienced factors influencing the implementation, and the efficacy of the implementation process, were investigated. Findings were compared with previous research in the Netherlands.
Method: A qualitative multiple case study design was applied. Checklist on anticipated facilitators and barriers to the implementation and semi-structured interview were completed by stakeholders, respectively at the end and at the beginning of the preparation phase.
Results: Overall, few differences between countries were founded. Facilitators for all countries were: added value of MCSP matching needs of the target group, evidence of effectiveness of MCSP, enthusiasm of stakeholders. General barriers were: competition with existing care and welfare organizations and scarce funding. Some countries experienced improved collaborations, others had difficulties finding a socially integrated location for MCSP. The step-by-step implementation method proved efficacious.
Conclusion: These insights into factors influencing the implementation of MCSP in three European countries and the efficacy of the step-by-step preparation may aid further implementation of MCSP in Europe.
The complete charge-coupled device light curves in B, V, R, and I bands of the short-period binary system, AE Phe, are presented. It is found that the light curves of AE Phe belong to typical EW-type ...light variation. Photometric solutions were derived by using the 2003 version of the Wilson-Devinney code. It showed that AE Phe is a W-subtype shallow-contact system (f = 14.6%(+/-0.5%)) with a mass ratio of q = 2.5491(+/-0.0092). The temperature difference between the two components is 227 K. Analysis of the O - C curve suggests that the period of AE Phe shows a long-term continuous increase at a rate of dP/dt = +6.17(+/-0.44) X 10-8 days year-1. The long-term period increase, the marginal-contact configuration, and the astrophysical parameters of the binary system, all suggest that it is a shallow-contact binary undergoing a thermal relaxation oscillation evolving into a detached binary.
•Corrosion rates of non-ferrous metals embedded in mortar were measured.•Copper and lead showed low to moderate corrosion level.•Aluminium showed a high corrosion level.•First attempt to use ...classical electrochemical techniques to non-ferrous metals.
In structural engineering, aluminium, copper and lead usually get into contact with cementitious materials and may be prone to corrode. From weight loss tests a ranking of these materials in terms of their corrosion resistance in mortar was established. To evaluate whether the use of conventional electrochemical techniques is appropriate to assess the corrosion rate of these metals when embedded in mortar, weight loss determinations were followed by measurements of the polarization resistance to compare the electrochemical results with the actual corrosion rate of the metals. Consistent results were obtained only on copper and lead.
Copper wire is the main component of a type of intrauterine device used as a contraceptive. Its contraceptive effect is attributed to the copper ions released as a result of the dissolution of copper ...in the uterus. Even though 10-year intrauterine device life is estimated on the basis of the dissolution rate of copper measured in vivo and in vitro, some cases of breakdown or fragmentation of the copper wire after short periods of insertion (2–3
months) have been reported. Due to the possible existence of residual stresses as a consequence of the manufacturing process, stress corrosion cracking has been previously proposed as an explanation for the early ruptures. In the present work, the susceptibility of copper wires to stress corrosion cracking in simulated uterine fluids was investigated. Results indicate that early ruptures should not be attributed to stress corrosion cracking. They could be explained by considering the increase in corrosion rate under certain conditions (pH decrease during infections; changes in the concentration of organic components along the menstrual cycle; etc.) that reduces the wire section leading to the rupture of the specimen by overloading.
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