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).
Occupational Rhinitis
John C Watkinson, Raymond W Clarke, Louise Jayne Clark, Adam J Donne, R James A England, Hisham M Mehanna, Gerald William McGarry, Sean Carrie in Basic Sciences Endocrine Surgery Rhinology, 2018
Corrosive reactions may also occur due to excessive concentrations of irritating and soluble chemical gases. Substances implicated in causing corrosion are ammonia, hypochloric acid, vinyl chloride, organic sulphur containing compounds, acrylamide, cyanide, nitriles and organophosphoside compounds.1 Disorders of olfaction may occur a result of rhinitis or as a direct effect of irritants on the olfactory receptors and their central connections.13 Anosmia and hyposmia have been reported after single high-dose exposure to sulphuric acid, hydrogen selenide, phosphorus oxychloride and a mixture of pepper and cresol.8 Other case reports of olfactory disorders present workers chronically exposed to low levels of chemicals such as benzene, benzol, cadmium, carbon disulphide, ethyl acetate, formaldehyde, hydrazine, menthol, solvents, and oil of peppermint.8,14 However, olfactory disorders in occupational rhinitis are otherwise under-investigated.
Radiation protection in the nuclear industry
Alan Martin, Sam Harbison, Karen Beach, Peter Cole in An Introduction to Radiation Protection, 2018
When the reactor is shut down, the primary shield gives adequate protection against the fission products in the core. The radiation hazard to personnel working on the primary system is caused by radioactivity within the system. The dose rate in the vicinity of the primary system tends to decay rapidly in the first 24 h after shutdown, mainly because of the decay of coolant activities or their cleanup by the treatment system. Thereafter, the levels do not change significantly from day to day. The half-lives of most of the radioactive corrosion products are in the range of 1 month to about 5 years. The dose rates vary considerably from reactor to reactor but, in systems with corrosion problems, levels of 10–100 mSv/h can be encountered on certain components. If the dose rate is excessive, it is sometimes possible to provide additional shielding on ‘hotspots.’ An alternative approach is to decontaminate the component, but this would be done only during major shutdown periods.
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.
Characterization of the biofilm grown on 304L stainless steel in urban wastewaters: extracellular polymeric substances (EPS) and bacterial consortia
Published in Biofouling, 2020
Islem Ziadi, Leila El-Bassi, Latifa Bousselmi, Hanene Akrout
The results obtained from the EPS content at defined times showed that the interactions between biofilm and EPS varied following this process: (1) In the first stage of biofilm establishment, the attachment of bacteria to the SS surface is enhanced and accelerated by EPS production. According to Jin et al. (2014b) the complexation of Fe2 + ions by polysaccharides and proteins configure the quorum sensing detection system of bacteria. and promoted the establishment and growth of the biofilm. The EPS network absorbed at this stage is heterogeneous, produces physical anomalies, and leads to an irregular mass transfer favoring the creation of a differential aeration cell (Jin et al. 2014b). (2) During biofilm maturation, the amount of EPS increased. Indeed, the large quantities of EPS produced caused the creation of a dense and uniform film, which would prevent the access of oxygen and thus hinder the cathodic reaction. These changes lead to the inhibition of the corrosion process. (3) In the final phase, the reduction in the quantity of PS leads to biofilm detachment and consequently accelerates the corrosion process.
The effect of orthopedic screw profiles on the healing time of femoral neck fracture
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Masoud Torabi, Siamak Khorramymehr, Mohammad Nikkhoo, Mostafa Rostami
Orthopedic implants are necessary for severe fractures – which need to be repaired and fixed for proper repair – or in cases where the bone is not able to regenerate at all and causes bone defects. The design of these implants requires considering the biocompatibility of materials, mechanical properties, and surface properties, as well as chemical properties and its destruction so that the material properties of the implant are close to the biomechanical properties of bone and integrate with native tissue while maintaining its integrity for the required duration (Tiffany et al. 2020). The mechanical stability of implants is also essential which is determined by mechanical properties of materials. The mechanical properties of implants should be comparable to the replaced or supported tissues. The chemical stability of the material is also essential to ensure corrosion and wear resistance in the harsh environment of the human body. The chemical instability of materials affects the biomechanical properties which includes both biological and mechanical properties (Kumar et al. 2018). Orthopedic screws are clinically recognized and accepted devices for fracture fixation and bone transplant stabilization. Bone screws can be used alone or in combination with plates to connect broken bone fragments. The use of screw surgery in an independent configuration is accepted for the treatment of hip capsular fractures, slip capital femoral epiphyses, distal femoral condyle fractures, and tibial plateau fractures, as well as for the treatment of ankle, elbow, and shoulder fractures (Perren et al. 1992).