Study on the disinfection effect of chlorine dioxide disinfectant (ClO2) on dental unit waterlines and its in vitro safety evaluation.

BACKGROUND: Ensuring the safety of dental unit waterlines (DUWLs) has become a pivotal issue in dental care practices, focusing on the health implications for both patients and healthcare providers. The inherent structure and usage conditions of DUWLs contribute to the risk of biofilm formation and bacterial growth, highlighting the need for effective disinfection solutions.The quest for a disinfection method that is both safe for clinical use and effective against pathogens such as Staphylococcus aureus and Escherichia coli in DUWLs underscores the urgency of this research. MATERIALS: Chlorine dioxide disinfectants at concentrations of 5, 20, and 80 mg/L were used to treat biofilms of S. aureus and E. coli cultured in DUWLs. The disinfection effectiveness was assessed through bacterial counts and culturing. Simultaneously, human skin fibroblast cells were treated with the disinfectant to observe changes in cell morphology and cytotoxicity. Additionally, the study included corrosion tests on various metals (carbon steel, brass, stainless steel, aluminum, etc.). RESULTS: Experimental results showed that chlorine dioxide disinfectants at concentrations of 20 mg/L and 80 mg/L significantly reduced the bacterial count of S. aureus and E. coli, indicating effective disinfection. In terms of cytotoxicity, higher concentrations were more harmful to cellular safety, but even at 80 mg/L, the cytotoxicity of chlorine dioxide remained within controllable limits. Corrosion tests revealed that chlorine dioxide disinfectants had a certain corrosive effect on carbon steel and brass, and the degree of corrosion increased with the concentration of the disinfectant. CONCLUSION: After thorough research, we recommend using chlorine dioxide disinfectant at a concentration of 20 mg/L for significantly reducing bacterial biofilms in dental unit waterlines (DUWLs). This concentration also ensures satisfactory cell safety and metal corrosion resistance.

Specifics and Methods of Inhibiting the Underfilm Corrosion of Carbon Steel.

The process of metal dissolution under a delaminated insulating polymer coating (underfilm dissolution) has been studied. For this purpose, we used an experimental setup that simulates the process of corrosion of underground metal structures in the presence of through defects in the polymer coating and/or extended areas of peeling of the polymer coating from the metal (loss of adhesion)-subfilm cavities partially or completely filled with electrolyte. In particular, the distribution of the protective current under a peeled polymer coating was studied, and a sharp decrease in the value of the protective current was shown at a distance of 1-3 cm from the edge of the defect with a gap between the metal and the coating of 1-6 mm. The localized nature of metal corrosion under the exfoliated polymeric coating has been demonstrated. The ratio of the areas with accelerated corrosion to the total area of the metal can be 1 to 100. It has been established that there are areas of anodic dissolution of the metal during cathodic polarization of the entire sample with a peeled coating. The activating effect of carbon dioxide and hydrogen sulfide on the corrosion and anodic dissolution of steel under the coating was shown. So, it has been established that the dissolution current flowing from the anodic sections on a surface can increase approximately 10 times in the presence of carbon dioxide and hydrogen sulfide. A synergistic effect of these compounds on the process of localized underfilm corrosion of steel was detected. It has been developed a mechanism for the formation of localized corrosion damage to steel under a delaminated polymeric coating, which can be the nuclei of corrosion cracks upon reaching a certain level of mechanical loads, i.e., stress corrosion cracking (SCC) of carbon steel. Possible manners of inhibiting underfilm dissolution of metals are considered, and a method for pre-treatment of the surface with solutions of organosilanes, which ensures the formation of surface self-assembled polymeric siloxane nanolayers responsible for inhibiting underfilm corrosion of steel, is proposed.

Frontiers and advances in N-heterocycle compounds as corrosion inhibitors in acid medium: Recent advances.

The acid solution is widely used in chemical cleaning, oil well acidifying, and other fields, which also brings the problem of metal corrosion that cannot be underestimated. However, adding an inhibitor is one of the most convenient and effective ways to slow down metal corrosion. N-heterocyclic compounds with high stability and durability, in line with the strategy of sustainable development, have been widely studied in an acidic environment. Imidazole, pyridine, and quinoline compounds, as the most commonly used corrosion inhibitors, can form a compact protective film via π electron cloud shifting towards the N atoms to generate coordination function. In particular, flexible modifiability makes N-heterocyclic compounds adapt to different corrosion environments readily, conducive to the formation of chemical bonds between compounds with metal surfaces to be better adsorption, so as to avoid the blemish of traditional inhibitors (such as inorganic salt and organic amines inhibitors) due to excessive usage, surface roughness of metal or environmental factor (for instance, temperature, pH and metallic) causing loose bonding between film and metal surface. More importantly, the efficient corrosion inhibition and toxicity of N-heterocyclic compounds have close to do with their own functional groups. Combined with the latest research achievement, the effects of different substituents on the corrosion inhibition and corrosion inhibition mechanisms were systematically reviewed in the acid-corrosive solution of imidazole, pyridine, and quinoline and their derivatives in this review article, respectively. In addition, the application and function of density functional theory in predicting the corrosion inhibition effect of corrosion inhibitors are also discussed. The future development trend was prospected according to the summarized research results.

Tracking the Progression of the Simulated Bronze Disease-A Laboratory X-ray Microtomography Study.

The internal three-dimensional characteristics of X-ray microtomography (micro-CT) has great application potential in the field of bronze corrosion. This work presents a method of simulating bronze disease based on an in situ micro-CT image to study the characteristics of the oxidative hydrolysis reactions of copper(I) chloride and copper(II) chloride dihydrate. A series of high-resolution reconstruction images were obtained by carrying out micro-CT at three key points throughout the experiment. We found that the reactions of copper(I) chloride and copper(II) chloride dihydrate showed different characteristics at different stages of the simulation in the micro-CT view. The method proposed in this work specifically simulated one single type of bronze corrosion and characterized the evolution characteristics of simulated bronze disease. It provides a new perspective to investigate bronze disease and can help improve the subsequent use of micro-CT to distinguish real bronze corrosions.

La and S Co-Doping Induced the Synergism of Multiphase Nickel-Iron Nanosheets with Rich Oxygen Vacancies to Trigger Large-Current-Density Oxygen Evolution and Urea Oxidation Reactions.

The development of cost-effective electrocatalysts for oxygen evolution reaction (OER) and urea oxidation reaction (UOR) is of great significance for hydrogen production. Herein, La and S co-doped multiphase electrocatalyst (LSFN-63) is fabricated by metal-corrosion process. FeOOH can reduce the formation energy of NiOOH, and enhance the stability of NiOOH as active sites for OER/UOR. The rich oxygen vacancies can increase the number of active sites, optimize the adsorption of intermediates, and improve electrical conductivity. Beyond, La and S co-doping can also regulate the electronic structure of FeOOH. As a result, LSFN-63 presents a low overpotential of 210/450 mV at 100/1000 mA cm-2 , small Tafel slope (32 mV dec-1 ), and outstanding stability under 1000 mA cm-2 @60 h, and can also display excellent OER activity with 180 mV at 250 mA cm-2 and long-term catalytic durability at 250 mA cm-2 @135 h in 30 wt% KOH under 60 °C. Moreover, LSFN-63 demonstrates remarkable UOR performance in 1 m KOH + 0.5 m urea, which just requires an ultra-small overpotential of 140 mV at 100 mA cm-2 , and maintain long-term durability over 120 h. This work opens up a promising avenue for the development of high-efficiency electrocatalysts by a facile metal-corrosion strategy.

Unexpected iron corrosion by excess sodium in two-dimensional Na-Cl crystals of abnormal stoichiometries at ambient conditions.

At ambient conditions, we found salt crystals formed from unsaturated solutions on an iron surface; these salt crystals had abnormal stoichiometries (i.e. Na2Cl and Na3Cl), and these abnormal crystals with Cl:Na of 1/2-1/3 could enhance iron corrosion. Interestingly, we found that the ratio of abnormal crystals, Na2Cl or Na3Cl, with ordinary NaCl was relative to the initial NaCl concentration of the solution. Theoretical calculations suggest that this abnormal crystallisation behaviour is attributed to the different adsorption energy curves between Cl--iron and Na+-iron, which not only promotes Na+ and Cl- adsorbing on the metallic surface to crystallise at unsaturated concentration but also induces the formation of abnormal stoichiometries of Na-Cl crystals for different kinetic adsorptionprocess. These abnormal crystals could also be observed on other metallic surfaces, such as copper. Our findings will help elucidate some fundamental physical and chemical views, including metal corrosion, crystallisation and electrochemical reactions.

Recent Progress of Polymeric Corrosion Inhibitor: Structure and Application.

An anti-corrosion inhibitor is one of the most useful methods to prevent metal corrosion toward different media. In comparison with small molecular inhibitors, a polymeric inhibitor can integrate more adsorption groups and generate a synergetic effect, which has been widely used in industry and become a hot topic in academic research. Generally, both natural polymer-based inhibitors and synthetic polymeric inhibitors have been developed. Herein, we summarize the recent progress of polymeric inhibitors during the last decade, especially the structure design and application of synthetic polymeric inhibitor and related hybrid/composite.

Ionic Liquids as Working Fluids for Heat Storage Applications: Decomposition Behavior of N-Butyl-N-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate.

Ionic liquids (ILs) represent promising working fluids to be used in thermal energy storage (TES) technologies thanks to their peculiar properties, such as low volatility, high chemical stability, and high heat capacity. Here, we studied the thermal stability of the IL N-butyl-N-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate ([BmPyrr]FAP), a potential working fluid for TES applications. The IL was heated at 200 °C for up to 168 h either in the absence or in contact with steel, copper, and brass plates to simulate the conditions used in TES plants. High-resolution magic angle spinning nuclear magnetic resonance spectroscopy was found to be useful for the identification of the degradation products of both the cation and the anion, thanks to the acquisition of 1H, 13C, 31P, and 19F-based experiments. In addition, elemental analysis was performed on the thermally degraded samples by inductively coupled plasma optical emission spectroscopy and energy dispersive X-ray spectroscopy. Our analysis shows a significant degradation of the FAP anion upon heating for more than 4 h, even in the absence of the metal/alloy plates; on the other hand, the [BmPyrr] cation displays a remarkable stability also when heated in contact with steel and brass.

Effect of Organosilicon Self-Assembled Polymeric Nanolayers Formed during Surface Modification by Compositions Based on Organosilanes on the Atmospheric Corrosion of Metals.

Reducing the risks caused by losses due to the atmospheric corrosion of metal structures has been relevant for many years and is an important scientific and technical task. Previously, for this purpose, the preliminary modification of the surface of structural metals with solutions of compositions, based on both individual organosilanes and their mixtures with amine-containing corrosion inhibitors, was proposed. Such treatment leads to the formation of self-assembled siloxane polymeric/oligomeric nanoscale layers on the metal surface, which are capable of changing the physicochemical properties of the metal surface (namely, by reducing the tendency of the metal to corrosive destruction). In this work, annual atmospheric corrosion tests of samples of steel, copper, zinc, and aluminum without protection, and samples modified with compositions based on organosilanes in an urban atmosphere, were carried out. It was established (by the gravimetric method) that the corrosion rate of unmodified (without protection) metals is as follows: steel-0.0022 mm/year; aluminum-0.0015 mm/year; copper-0.00018 mm/year; and zinc-0.00023 mm/year. Using gravimetry and optical microscopy, it was shown that the preliminary modification of metal surfaces with compositions based on organosilanes led to the inhibition of both uniform and local corrosion of metals. The corrosion rates of samples that were modified with one-component compositions decreased by almost two times. The maximum inhibitory effect for the studied systems was demonstrated by mixed binary modifying compositions: mixtures of vinyl- and aminosilane, vinylsilane, and benzotriazole. The corrosion rate decreased for all the studied metals. The minimum effect was observed on zinc (2.5 times) and the maximum inhibition of the corrosion rate was obtained on copper (5.1 times). The mechanism of corrosion inhibition by layers formed as a result of surface modification with two-component mixtures was considered.

A Biodegradable Metal-Polymer Composite Stent Safe and Effective on Physiological and Serum-Containing Biomimetic Conditions.

The new-generation coronary stents are expected to be biodegradable, and then the biocompatibility along with biodegradation becomes more challenging. It is a critical issue to choose appropriate biomimetic conditions to evaluate biocompatibility. Compared with other candidates for biodegradable stents, iron-based materials are of high mechanical strength, yet have raised more concerns about biodegradability and biocompatibility. Herein, a metal-polymer composite strategy is applied to accelerate the degradation of iron-based stents in vitro and in a porcine model. Furthermore, it is found that serum, the main environment of vascular stents, ensured the safety of iron corrosion through its antioxidants. This work highlights the importance of serum, particularly albumin, for an in vitro condition mimicking blood-related physiological condition, when reactive oxygen species, inflammatory response, and neointimal hyperplasia are concerned. The resultant metal-polymer composite stent is implanted into a patient in clinical research via interventional treatment, and the follow-up confirms its safety, efficacy, and appropriate biodegradability.

Extracellular Electron Exchange Capabilities of Desulfovibrio ferrophilus and Desulfopila corrodens.

Microbial extracellular electron transfer plays an important role in diverse biogeochemical cycles, metal corrosion, bioelectrochemical technologies, and anaerobic digestion. Evaluation of electron uptake from pure Fe(0) and stainless steel indicated that, in contrast to previous speculation in the literature, Desulfovibrio ferrophilus and Desulfopila corrodens are not able to directly extract electrons from solid-phase electron-donating surfaces. D. ferrophilus grew with Fe(III) as the electron acceptor, but Dp. corrodens did not. D. ferrophilus reduced Fe(III) oxide occluded within porous alginate beads, suggesting that it released a soluble electron shuttle to promote Fe(III) oxide reduction. Conductive atomic force microscopy revealed that the D. ferrophilus pili are electrically conductive and the expression of a gene encoding an aromatics-rich putative pilin was upregulated during growth on Fe(III) oxide. The expression of genes for multi-heme c-type cytochromes was not upregulated during growth with Fe(III) as the electron acceptor, and genes for a porin-cytochrome conduit across the outer membrane were not apparent in the genome. The results suggest that D. ferrophilus has adopted a novel combination of strategies to enable extracellular electron transport, which may be of biogeochemical and technological significance.

Compatibility Tests between Three Commercially Available Organic PCMs and Metals Typically Used in Fin-and-Tube Heat Exchangers.

Energy storage is one of the most effective ways to increase energy savings and efficiency of heating and air conditioning systems. Phase change materials (PCMs) are increasingly used in latent heat thermal energy storage (LHTES) systems to increase their capacity. In such systems, costs are a very important factor of viability so the typical heat transfer elements like fin-and-tube heat exchangers are used to construct the LHTES. The problem of this approach is a possibility of corrosion of metals in contact with PCM that shortens the life cycle of LHTES. Therefore, the main objective of this work is an experimental study of the compatibility of metals typically used in fin-and-tube heat exchangers (copper and aluminum) with three commercially available organic PCMs (RT15, RT18HC, and RT22HC). Compatibility of PCMs with copper and aluminum was tested for a period of approximately two months, during which a total of 35 heating and cooling cycles were carried out, each with a complete phase transition of the tested materials. In the course of the tests it was assessed whether the PCM caused corrosion of the tested metals. The evaluation was based on the gravimetric method, calculation of corrosion rate, and visual observations and measurements of the features on the metal sample's surface using optical microscope. It was determined that RT15, RT18 HC, and RT22 HC show low corrosion rates for aluminum and copper samples. The visual tests indicate that there was no change in the PCM solutions during the tests, only a sediment was observed for the samples with the combination of copper and aluminum. Microscopic examination of the surface of the samples did not show any significant surface changes, except for the aluminum samples, on the surface of which local microdefects were observed. It follows from the present results that copper and aluminum can be used to design the heat transfer surface in contact with the chosen PCMs.

Eco-friendly deicer prepared from waste oyster shells and its deicing properties with metal corrosion.

Calcium acetate eco-friendly deicer was prepared using waste oyster shell as a raw reactant material and its physicochemical properties were investigated. The waste oyster shells were converted to a calcium acetate deicer by reaction with acetic acid at ambient temperature. The physicochemical properties of the prepared calcium acetate deicer were analysed using various analytical method. The ice melting and metal corrosion characteristics of the calcium acetate deicer synthesized from the waste oyster shell were evaluated by comparison with those of the calcium chloride and sodium chloride deicers. The chloride deicers severely corroded the metal, but the calcium acetate deicer prepared from the waste oyster shell did not cause metal corrosion. The ice melting performance of calcium acetate prepared from the waste oyster shell was lower than that of calcium chlorides, however, the addition of sodium hydroxide could significantly improve the ice melting capacity.

Laboratory simulation of uranium metal corrosion in different soil moisture regimes.

A novel laboratory simulation system has been developed for the study of the corrosion of uranium metal in soils. Corrosion and transportation of depleted uranium (DU) as the metal undergoes weathering as a buried material within the soil environment. The corrosion of uranium metal in soil was not well understood due to the gas-liquid-solid phase of the soil. This study presents a novel method to investigate the change of uranium species during the process of process of oxidation of metallic uranium in these environments. Compared with other techniques used for the study of environmental corrosion of metals in soils, this method has the advantage of low secondary uranium pollution, no energy consumption, and ease of operation. The simulation system has been used for the following studies: •Simultaneously simulate the corrosion of uranium metal in different soil moisture regimes•Study the influence of biogeochemical factors on the corrosion of uranium metal•Investigate the change of uranium species during oxidation.

The role of biofilms in the corrosion of steel in marine environments.

Metal corrosion is a major global concern in many economic sectors. The degradation of metal surfaces is responsible for losses in values that account for about 3% of gross domestic product (GDP) only in the US. Parts of all corrosion processes described in different environments are present mainly in marine environments. The marine environment is characterized as favoring the corrosion processes of several metallic alloys, damaging structures used in the construction of ships, ports, oil pipelines, and others. Despite chemical corrosion being the most frequently described in these environments, studies show the participation of microorganisms in direct corrosion processes or in the acceleration/influence of the corrosive action, through the formation of complex biofilms. These structures create favorable conditions for microorganisms to degrade metal surfaces, causing damage known as pitting and crevices. Currently, diverse technicians are employed in biocorrosion research, e.g. electronic microscopy, and DNA sequencing. These techniques have clarified the dynamic process of the formation of biofilm structures, allowing understanding of the succession of different species during the evolution of the structure. Improving the understanding of how this interaction between biofilm and metallic surface occurs will enable better evaluation of strategies to avoid or decelerate the degradation of metallic structures in marine environments.

Corrosion and Fretting of a Modular Hip System: A Retrieval Analysis of 60 Rejuvenate Stems.

Femoral stems with dual-taper modularity were introduced to allow independent control of length, offset, and version. Corrosion and fretting related to micromotion at the neck-stem junction are thought to stimulate an adverse local tissue reaction (ALTR). Analysis of 60 consecutively retrieved modular-neck stem implants (Rejuvenate, Stryker) revised primarily for ALTR was done to determine the variables influencing corrosion and fretting patterns at the neck-stem interface. Taper damage evaluation was performed with stereomicrocopic analysis with two observers. Evidence of fretting and corrosion was seen at the neck-stem taper in all implants, including three implants revised for periprosthetic fractures within four weeks of the index surgery indicating that this process starts early. Femoral stems paired with the long overall neck lengths had significantly higher corrosion scores. Correlation of the corrosion severity at particular locations with the length of implantation suggests that the neck-stem junction experiences cyclic cantilever bending in vivo. The positive correlation between the length of implantation and fretting/corrosion scores bodes poorly for patients who still have this implant. Scanning electron microscopy on a subset of specimens was also performed to evaluate the black corrosion material. We strongly urge frequent follow-up exams for every patient with this particular modular hip stem.

Adverse clinical outcomes in a primary modular neck/stem system.

We report our experience with 215 recalled neck modular stems due to corrosion. Among the 195 hips with 2 years follow-up, 56% had no clinical symptoms, 26% had groin pain (typical of corrosion), and 17% had other symptoms. Cobalt levels were comparable between asymptomatic (3.4 µg/L, range 0.7-7.3 µg/L) and symptomatic patients (4.0 µg/L range 0-13.2 µg/L). Abnormal imaging findings were seen in 46% of symptomatic and 11% of asymptomatic hips (P=0.001). Twenty-six hips (13%) have either undergone revision surgery or have been scheduled. Evidence of corrosion was seen at revision surgery in all patients. Despite modest elevations in serum cobalt levels, abnormal imaging studies were seen in 36%, clinical symptoms were seen in 44%, and revision for corrosion was undertaken or scheduled in 13% of the hips.