Nickel Metal and Alloys
Jurij J. Hostýnek, Howard I. Maibach in Nickel and the Skin, 2019
The patch test represents a simple configuration that is generally undisturbed, usually for the 48 h test period. Acidity tends to develop in the creviced region due to hydrolysis of corrosion products, particularly if high valency ions such as Cr+++ are involved. In real life, articles in contact with the skin are often of complex shape and are not undisturbed, and the contact is rarely as tight or for as long a period as 48 h. Thus the patch test provides exposure conditions much more severe than those occurring in practice. Furthermore, the conditions developed in the patch test may differ substantially from those employed in tests in artificial sweat to determine release of nickel from articles intended to come into contact with the skin (CEN EN 1811:1998). Thus a discrepancy can occur in results from patch testing and those from nickel-release tests (see Figure 9.2) (Flint, 1998).
Aircraft Decontamination and Mitigation
Brian J. Lukey, James A. Romano, Salem Harry in Chemical Warfare Agents, 2019
To mitigate these challenges, hardware designers can, to a degree, address the chemistry of the threat by employing techniques for both conventional chemicals and chemical warfare hazards. Today, aircraft and systems that deploy globally must deal with a wide range of environmental chemicals that can corrode materials. Pollutants such as ozone and NOx can slowly eat away at exposed materials, and operating in salt air environments can corrode exposed metals. This damage is evidenced by billions of dollars spent annually on fighting corrosion from many environmental sources. From a corrosion prevention perspective, one key tool is employing coatings to protect materials from environments that degrade substrates over time. These coatings, designed to provide corrosion protection, can also serve as barriers to control agent absorption. For example, CARC, which was originally designed to resist chemicals, also serves to mitigate corrosion, thus reflecting dual roles on equipment. CARC formulations continue to evolve to improve its protective properties (Escarsega and Smith, 2009).
Mechanical Effects of Cardiovascular Drugs and Devices
Michel R. Labrosse in Cardiovascular Mechanics, 2018
Annuloplasty rings are usually constructed of a PTFE core covered with polyester fabric, which can be a source of thromboembolism. Some materials cause blood damage and must be verified for hemocompatibility and hemolysis. Excessive stress resulting from heart dilation or overload may cause ring fracture. Material defects, including corrosion, may weaken material, resulting in failure. Dehiscence at the suture line is observed in some patients, which allows a paravalvular orifice for regurgitant flow. Clinical complications from annuloplasty result from a variety of sources, including progression of native cardiovascular disease. Although regurgitation is greatly reduced following proper repair, some of it may still be present and worsen with time. Reoperation for additional repair or valve replacement should be done before a decline in ventricular function occurs. Valvular stenosis may progress following annuloplasty, resulting in blood flow abnormalities and ultimately leading to fibrosis and calcification of the valve.
Biofouling occlusion of ships’ internal seawater systems: operational, economic, and biosecurity consequences
Published in Biofouling, 2023
Ian Davidson, Patrick Cahill, Arne Hinz, Robert Major, Daniel Kluza, Chris Scianni, Eugene Georgiades
Ships’ ISS consist of intake and discharge pipework, pumps, and equipment that convey seawater for temperature control (engines), cooling (refrigeration and air conditioning), and water provision for ballast, steam, freshwater-generator, and firefighting systems (Davidson et al. 2021). ISS are integral to vessel function and their design and construction are complex components of shipbuilding and a significant part of a ship’s capital costs (Pérez et al. 2020). Available colonisation space for biofouling within ISS is orders of magnitude lower than external hull surfaces, but ships’ ISS can be more prone to biofouling due to their sheltered nature and inherent challenges to effective antifouling system protection (Coutts and Dodgshun 2007; Frey et al. 2014; Lewis 2016). In addition, restricted spaces within ISS means relatively modest biofouling accumulation can exert strong impacts on system integrity and operations (Davidson et al. 2021). These impacts include surface roughness, restricted flow, corrosion, loss of surface function, and contamination which may result in unscheduled maintenance (Lewis and Smith 1991; Grandison et al. 2011; Growcott et al. 2017; USCG (United States Coast Guard) 2018; Figure 1).
Protocol with non-toxic chemicals to control biofilm in dental unit waterlines: physical, chemical, mechanical and biological perspective
Published in Biofouling, 2022
Rachel Maciel Monteiro, Viviane de Cassia Oliveira, Rodrigo Galo, Denise de Andrade, Ana Maria Razaboni, Evandro Watanabe
Product A showed the greatest tendency to corrosion of stainless-steel samples. According to current density, Product B and Product AB had a similar curve and were statistically similar to the control. As the corrosion process develops, the chemical molecules that compose a material are transformed by their electrochemical reactions. In addition to oxidation, which implies the loss of electrons, reduction can promote an increase in the number of electrons (Gentil, 1996). Corrosion is the result of a process of the environment in each material, causing surface damage. Furthermore, electrochemical corrosion is a spontaneous process, which occurs in an aqueous environment when the metal is in contact with an electrolyte, in which anodic (electron loss) and cathodic (electron gain) reactions occur simultaneously (Revie and Uhlig 2008). Generally, 316 L stainless steel is attractive for biomedical applications due to its excellent corrosion resistance (Hryniewicz et al. 2009). It should be noted that the corrosion experiments in this study extrapolate the reality that would be carried out in dental clinical practice regarding exposure time and concentration of products with the dental unit components made of stainless steel, for example triple syringes and high-speed handpieces.
From laboratory tests to field trials: a review of cathodic protection and microbially influenced corrosion
Published in Biofouling, 2022
A. A. Thompson, J. L. Wood, E. A. Palombo, W. K. Green, S. A. Wade
Beyond the financial burdens associated with MIC, it also causes a variety of other challenges, with a key difficulty being the identification of the phenomenon. Corrosion comes in a variety of different forms, such as galvanic or crevice corrosion, and abiotic processes that can also lead to localised accelerated corrosion attacks. As such, the presence/detection of certain microbes alone is not a guarantee that MIC is responsible for the degradation (Little et al. 2006; Wade et al. 2011). Once MIC has been identified, other challenges arise surrounding the treatment and prevention of further MIC (Javaherdashti 2017b; Little et al. 2020). Treatment incurs costs in both time and money as the structures suffering from MIC need to be cleaned and repaired where necessary. MIC can also occur in places where traffic (e.g. shipping) and location (e.g. below water level) can present additional difficulties in identification and remediation.