152 research outputs found
Cancer Therapy with Heavy Particles
No full textConventional radiotherapy techniques for the treatment of malignant tumours are known to carry some risk as a method of combatting cancerous cells. The damage caused to healthy tissue as a part of these treatments poses a significant obstacle to overcome in the fields of radiobiology and oncology. The use of linear particle accelerators and cyclotrons to generate beams of charged radioactive particles for use in cancer therapy has been developed over recent years, and new and more effective cancer treatments such as hadron therapy have been made possible because of experimental particle physics and hold the promise of greater survival rates for patients. The effectivity of such particle physics based treatments is discussed here, and potential new treatments explored
Effect of sterilization treatment on the corrosion behavior of NiTi endodontic instruments
No full textThis study investigates the influence of the sterilization treatment conducted at 50 °C in 5% sodium hypochlorite solution (NaClO) on the corrosion behavior of endodontic instruments made of NiTi alloy (GT Rotary and K3) and stainless steel (K File) by measuring potentiodynamic polarization curves in the same environment at 37°C. For the sake of comparison, the electrochemical characterization was also carried out on endodontic instruments that were not sterilized. The characterization of the sample surface after the electrochemical tests were carried out by means of scanning electron microscopy (SEM) coupled with X-ray energy dispersive spectroscopy (EDX). There was no significant influence of the sterilization treatment on the corrosion behavior of K File and GT Rotary endodontic instruments. On the contrary, a negative influence of the sterilization treatment on the corrosion resistance of K3 endodontic instruments was observed, and the effect appears to be more dramatic for longer treatment periods
Influence of iodide ions on corrosion of dual‐phase steel in sulfuric acid solution
No full textPotassium iodide was studied for its corrosion inhibition property on the corrosion of dual‐phase steel in 0.5M sulfuric acid at 25°C by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Scanning electron microscopy was used to characterize the steel surface. The inhibition efficiency increases with the concentration of iodide ions. The thermodynamic parameters Kads and ΔG0ads are calculated and discussed. The probable inhibitive mechanism is proposed from the viewpoint of adsorption theory
Influence of noble metals alloying additions on the corrosion behaviour of titanium in a fluoride-containing environment
No full textTitanium alloys exhibit excellent corrosion resistance in most aqueous media due to the formation of a stable oxide film, and some of these alloys (particularly Ti-6Al-7Nb) have been chosen for surgical and odontological implants for their resistance and biocompatibility. Treatment with fluorides (F-) is known to be the main method for preventing plaque formation and dental caries. Toothpastes, mouthwashes, and prophylactic gels can contain from 200 to 20,000 ppm F- and can affect the corrosion behaviour of titanium alloy devices present in the oral cavity. In this work, the electrochemical corrosion behaviour of Ti-1M alloys (M = Ag, Au, Pd, Pt) was assessed in artificial saliva of pH = 3.0 containing 910 ppm F- (0.05 M NaF) through open circuit potential, E-OC, and electrochemical impedance spectroscopy (EIS) measurements. The corrosion behaviour of the Ti-6Al-7Nb commercial alloy was also evaluated for comparison
Enhanced corrosion resistance of austenitic Fe-Mn-C TWIP steel by cerium(III) in 1M hydrochloric acid pickling solution
No full textThe influence of rare earth Ce3+ ions on the corrosion behaviour of Fe-Mn-C TWIP steel in 1M hydrochloric acid solution was studied by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Electrochemical corrosion tests showed that Ce3+ can significantly reduce corrosion deterioration up to 1.0mM. Beyond that level the corrosion rate increases till a steady value. Surface film resistance increases with time evolution until 24 h, then decreases and stabilises. High corrosion protection of steel surface after 24 h exposure to the acidic solution containing the optimal Ce3+ ion concentration is revealed by SEM investigations
Corrosion inhibition of aluminium alloy AA7075-T6 by sodium silicate in chloride solution
No full textThe influence of sodium silicate on the corrosion behaviour of aluminium alloy 7075-T6 in 0.1 M sodium chloride solution was studied by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) techniques. Scanning electron microscopy (SEM) was used to characterize the AA7075-T6 surface. Silicate can significantly reduce corrosion deterioration and the inhibition efficiency increases with the concentration of Na2SiO3. The corrosion inhibition mechanism involves the formation of a protective film over the alloy surface by adsorption of aluminosilicate anions from solution, as has also been suggested by others in literature
Corrosion behavior of new ternary zirconium alloys as alternative materials for biomedical applications
No full textThe in vitro corrosion behavior of four Zrâ€based alloys (Zr97.5Nb1.5VM1.0; VM 1â„4 valve metal: Ti, Mo, W, Ta; at%) to be used as implant materials has been assessed and compared with that of Grade 2 Ti, which is known to be a highly compatible metal standard. Corrosion resistance was investigated by open circuit potential and electrochemical impedance spectroscopy (EIS) measurements, as a function of exposure time to an artificial physiological environment (Ringer's solution). Open circuit potential values indicated that Zrâ€based alloys and Grade 2 Ti undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the simulated aggressive environment. It also indicated that the tendency for the formation of a spontaneous oxide is greater for the Zr97.5Nb1.5Ta1.0 alloy and that this oxide has better corrosion protection characteristics than the ones formed on Grade 2 Ti or on Zr97.5Nb1.5Ti1.0, Zr97.5Nb1.5Mo1.0, and Zr97.5Nb1.5W1.0 alloys. EIS study showed high impedance values for all samples, increasing with exposure time, indicating an improvement in corrosion resistance of the spontaneous oxide film.The fit obtained suggests a single passive film present on the metals surface, improving their resistance with exposure time, presenting the highest values to the Zr97.5Nb1.5Ta1.0 alloy. All these electrochemical results suggest that Zr97.5Nb1.5VM1.0 alloys are promising materials for osteoâ€synthesis prosthetic devices, since corrosion stability is directly associated with biocompatibility and is a necessary condition for applying a material as biomateria
Corrosion inhibition of high strength maraging steel by cerium(III) ions in sulfuric acid solution
No full textThe influence of rare earth Ce(III) ions on the corrosion behaviour of high strength maraging steel in 0.5 M sulfuric acid solution was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Ce3þ can significantly reduce corrosion deterioration up to 5.0 mM. Beyond that level the corrosion rate increases till a steady value. High corrosion protection of steel surface after exposure to the acidic solution containing the optimal Ce(III) concentration is revealed by SEM investigation
Influence of rare earths alloying addition on the corrosion behavior of Zn in neutral aerated sodium chloride solution
No full textThe effect of rare earth metals (Gd, Dy, Er,) addition on the corrosion behavior of Zn
has been investigated. The corrosion resistance of Zn 99 Gd 1 , Zn 99 Dy 1 , and Zn 99 Er 1
(at%) alloys has been assessed by open circuit potential and electrochemical
impedance spectroscopy (EIS) measurements carried out in a 0.1 M NaCl solution, at
approximately neutral pH, without stirring and in contact with the air. For
comparison, the electrochemical tests have also been carried out on unalloyed Zn.
Moreover, the surface morphology and nature of the corrosion products have been
investigated. The results indicated that rare earths addition significantly improves the
corrosion behavior of unalloyed Zn. This improvement is most likely due to enhanced
barrier properties of the corrosion products layer and additional active corrosion
protection originated from the inhibiting action of the lanthanide ions entrapped as
oxides/hydroxides in this surface layer
Influence of cerium(III) ions on corrosion of TRIP 800 steel in hydrochloric acid solution
No full textCe(III) was studied for its corrosion inhibition property on the corrosion of TRIP 800 C-Mn-Si steel in 0.5 M hydrochloric acid at 258C by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. SEM was used to examine the specimen surface exposed to 0.5 M HCl containing the optimal threshold Ce(III) concentration (2.5 mM). A model for the corrosion process mechanism and inhibition by Ce(III) salt for TRIP 800 steel in the tested medium is proposed
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