120 resultados para Corrosion testing and monitoring


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Within the marine environment, aerial surveys have historically centred on apex predators, such as pinnipeds, cetaceans and sea birds. However, it is becoming increasingly apparent that the utility of this technique may also extend to subsurface species such as pre-spawning fish stocks and aggregations of jellyfish that occur close to the surface. In light of this, we tested the utility of aerial surveys to provide baseline data for 3 poorly understood scyphozoan jellyfish found throughout British and Irish waters: Rhizostoma octopus, Cyanea capillata and Chrysaora hysoscella. Our principal objectives were to develop a simple sampling protocol to identify and quantify surface aggregations, assess their consistency in space and time, and consider the overall applicability of this technique to the study of gelatinous zooplankton. This approach provided a general understanding of range and relative abundance for each target species, with greatest suitability to the study of R. octopus. For this species it was possible to identify and monitor extensive, temporally consistent and previously undocumented aggregations throughout the Irish Sea, an area spanning thousands of square kilometres. This finding has pronounced implications for ecologists and fisheries managers alike and, moreover, draws attention to the broad utility of aerial surveys for the study of gelatinous aggregations beyond the range of conventional ship-based techniques.

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The traditional drug discovery pipeline for the identification and development of compounds that selectively target specific molecules to ameliorate disease remains a major focus for medical research. However, the zebrafish is increasingly providing alternative strategies for various components of this pipeline. Zebrafish and their embryos are small, easily accessible and relatively low cost, making them applicable to high-throughput, small molecule screening. Zebrafish can also be manipulated by a range of forward and reverse genetics techniques to facilitate gene discovery and functional studies. Moreover, their physiological and developmental complexity provides accurate models of human disease to underpin mechanism of action and in vivo validation studies. Finally, several of these biological characteristics make zebrafish eminently suitable for toxicity testing, including eco-toxicology. Here we review the application of zebrafish to preclinical drug development and toxicity testing, including recent advances in mutant generation, drug screening and toxicology that serve to further enhance the capabilities of this valuable model organism in drug discovery.

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The contrubution of this thesis is to generate fundamental research and design information on the impact and bending behaviours of metal foams and foam-filled tubes

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Magnesium (Mg) based alloys have been extensively considered for their use as biodegradable implant materials. However, controlling their corrosion rate in the physiological environment of the human body is still a significant challenge. One of the most effective approaches to address this challenge is to carefully select alloying compositions with enhanced corrosion resistance and mechanical properties when designing the Mg alloys. This paper comprehensively reviews research progress on the development of Mg alloys as biodegradable implant materials, highlighting the effects of alloying elements including aluminum (Al), calcium (Ca), lithium (Li), manganese (Mn), zinc (Zn), zirconium (Zr), strontium (Sr) and rare earth elements (REEs) on the corrosion resistance and biocompatibility of Mg alloys, from the viewpoint of the design and utilization of Mg biomaterials. The REEs covered in this review include cerium (Ce), erbium (Er), lanthanum (La), gadolinium (Gd), neodymium (Nd) and yttrium (Y). The effects of alloying elements on the microstructure, corrosion behavior and biocompatibility of Mg alloys have been critically summarized based on specific aspects of the physiological environment, namely the electrochemical effect and the biological behavior. This journal is © the Partner Organisations 2014.

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Mg alloys are attractive candidate materials for biodegradable stents. However, there are few commercially available Mg-based stents in clinical use because Mg alloys generally undergo rapid localized corrosion in the body. In this study, we report a new surface coating for Mg alloy AZ31 based on a low-toxicity ionic liquid (IL), tributyl(methyl)phosphonium diphenyl phosphate (P1,4,4,4 dpp), to control its corrosion rate. Emphasis is placed on the effect of treatment temperature. We showed that enhancing the treatment temperature provided remarkable improvements in the performances of both corrosion resistance and biocompatibility. Increasing treatment temperature resulted in a thicker (although still nanometer scale) and more homogeneous IL film on the surface. Scanning electron microscopy and optical profilometry observations showed that there were many large, deep pits formed on the surface of bare AZ31 after 2 h of immersion in simulated body fluid (SBF). The IL coating (particularly when formed at 100 °C for 1 h) significantly suppressed the formation of these pits on the surface, making corrosion occur more uniformly. The P1,4,4,4 dpp IL film formed at 100 °C was more hydrophilic than the bare AZ31 surface, which was believed to be beneficial for avoiding the deposition of the proteins and cells on the surface and therefore improving the biocompatibility of AZ31 in blood. The interaction mechanism between this IL and AZ31 was also investigated using ATR-FTIR, which showed that both anion and cation of this IL were present in the film, and there was a chemical interaction between dpp(-) anion and the surface of AZ31 during the film formation.

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Extruded Mg-1Mn-2Zn-xNd alloys (x=0.5, 1.0, 1.5 mass %) have been developed for their potential use as biomaterials. The extrusion on the alloys was performed at temperature of 623K with an extrusion ratio of 14.7 under an average extrusion speed of 4mm/s. The microstructure, mechanical property, corrosion behavior and biocompatibility of the extruded Mg-Mn-Zn-Nd alloys have been investigated in this study. The microstructure was examined using X-ray diffraction analysis and optical microscopy. The mechanical properties were determined from uniaxial tensile and compressive tests. The corrosion behavior was investigated using electrochemical measurement. The biocompatibility was evaluated using osteoblast-like SaOS2 cells. The experimental results indicate that all extruded Mg-1Mn-2Zn-xNd alloys are composed of both α phase of Mg and a compound of Mg7Zn3 with very fine microstructures, and show good ductility and much higher mechanical strength than that of cast pure Mg and natural bone. The tensile strength and elongation of the extruded alloys increase with an increase in neodymium content. Their compressive strength does not change significantly with an increase in neodymium content. The extruded alloys show good biocompatibility and much higher corrosion resistance than that of cast pure Mg. The extruded Mg-1Mn-2Zn-1.0Nd alloy shows a great potential for biomedical applications due to the combination of enhanced mechanical properties, high corrosion resistance and good biocompatibility.

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This paper presents a hypothesis and its experimental validation that simultaneous improvement in the hardness and corrosion resistance of aluminium can be achieved by the combination of suitable processing route and alloying additions. More specifically, the corrosion resistance and hardness of Al- xCr (x= 0-10 wt.%) alloys as produced via high-energy ball milling were significantly higher than pure Al and AA7075-T651. The improved properties of the Al- xCr alloys were attributed to the Cr addition and high-energy ball milling, which caused nanocrystalline structure, extended solubility of Cr in Al, and uniformly distributed fine intermetallic phases in the Al-Cr matrix.

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Percival Faraday Thompson (P F Thompson, PFT), (1885-1951),(Figure1), a metallurgistand chemical analyst, is widely considered as Australia’s pioneer in corrosion science and education. Each year at the annual ACA Conference, the P F Thompson Memorial Lectureis presented by a person who has made a most significant contribution to corrosion science and engineering in Australia. While each presenter usually gives a few detailsof the work of PFT for the benefit of Conference attendees, the entire body of his work and details about his life are not provided due to the limitations on the lecture duration. A review of Thompson’s life and some of his work is available in the ‘Australasian Corrosion Engineering’ publication which was the ACA publication in the early 70s, and is one of theprecursors to the current ACA publication Corrosion & Materials (Potter, 1972). However this publication is not widely available to the ACA membership, and certainly not inelectronic format. The purpose of this paper is to provide readers with some of the history of the PFT Lecture, and to acquaint readers of ‘Corrosion & Materials’ and the broader corrosion prevention community with the breadth of the scientific work of PFT and his enthusiasm for describing corrosion science through practical public demonstrations ofexperiments of the basic principles of corrosion.

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Quality testing by suppliers has significant ramifications for downstream supply chain participants and retail consumers. This article focuses on such implications accounting for the fact that suppliers often enjoy discretion in quality testing and reporting. Under a discretionary testing and reporting environment, we show that a supplier can improve the market's perception of product quality by engaging in self-imposed production cuts. Production cuts dampen supplier incentives to engage in excessive quality testing, putting the supplier and the market on a more equal information footing. This reduces the market's need to skeptically discount product quality to protect itself. The improved market perception, then, reduces quality testing demand, introducing cost savings. The result that costly production cuts can improve quality perceptions indicates that the groundwork for influencing market perceptions may have to be laid upfront, even prior to acquiring private information, providing a contrast to routine signaling models.

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Corrosion testing (half-cell and LPR) was carried out on a number reinforced concrete panels which had been taken from the fascia of a twenty five year old high rise building in Melbourne, Australia. Corrosion, predominantly as a result of carbonation of the concrete, was associated with a limited amount of cracking. A monitoring technique was established in which probe electrodes (reference and counter) were retro-fitted into the concrete. The probe electrode setup was identical for all panels tested. It was found that the corrosion behaviour of all panels tested closely fitted a family of results when the corrosion potential is plotted against the polarisation resistance (Rp). This enabled the development of a so-called 'control curve' relating the corrosion potential to the Rp for all of the panels under investigation. This relationship was also confirmed on laboratory samples, indicating that for a fixed geometry and experimental conditions a relationship between the potential and polarisation resistance of steel can be established for the steel-concrete system. Experimental results will be presented which indicate that for a given monitoring cell geometry, it may be possible to propose criteria for the point at which remediation measures should be considered. The establishment of such a control curve has enabled the development of a powerful monitoring tool for the assessment of a number of proposed corrosion remediation techniques. The actual effect of any corrosion remediation technique becomes clearly apparent via the type and magnitude of deviation of post remediation data from the original (preremediation) control curve.

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Underground pipeline corrosion monitoring is a complex technical challenge. Currently there is no corrosion monitoring probe that is able to provide in situ information on corrosion under disbonded coatings. This paper presents a proof of concept of a novel corrosion monitoring probe intended to simulate corrosion under disbonded pipeline coatings and monitor its rate under Cathodic Protection (CP). The probe's capabilities to measure corrosion rates and simulate disbonded coating conditions are illustrated by a typical experiment that involved testing of the probe in 0.1M NaCl at -850mVCSE. Estimated metal thickness losses based on results measured by the probe were compared against corrosion patterns and profilometry measurements of control specimens exposed to the same conditions.