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A series of novel 1- N -α-d-glucopyranosyl-1 H -1,2,3-triazole xanthines was synthesized from azido sugars (glucose, galactose, and lactose) and propargyl xanthines (theophylline and theobromine) using a typical copper (I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition. The corrosion inhibition activities of these new carbohydrate-xanthine compounds were evaluated by studying the corrosion of API 5 L X70 steel in a 1 M HCl medium. The results showed that, at 10 ppm, a 90% inhibition efficiency was reached by electrochemical impedance spectroscopy. The inhibitory efficiency of these molecules is explained by means of quantum chemical calculations of the protonated species with the solvent effect, which seems to better represent the actual situation of the experimental conditions. Some quantum chemical parameters were analyzed to characterize the inhibition performance of the tested molecules., Competing Interests: The authors declare no conflict of interest.

Converting industrial wastes into value-added building products in an environmental management strategy is a challenging yet vital component of the industrial process. Steel slag (SS), an industrial waste by-product from the steel-making process, is typically disposed of in landfill which consumes land resources and pollutes the environment. This paper explores the possibility of a closed-loop system to convert steel slag into a cement material through carbonation activation, thereby significantly reducing the amount of steel slag waste sent to landfills across Canada. The production of this cementing material can occur next to the steel mill, utilizing steel slag and carbon dioxide collected on-site to fabricate carbon-negative products. To save energy and allow production to be feasible on an industrial scale, ambient pressure (AP) carbonation is developed to reduce carbon emissions while improving their performance. High pressure (HP) carbonation curing and normal hydration (NH) references were also implemented at the same time to justify the application of AP carbonation in reducing CO 2 emission. The results of this study found AP carbonation-activated SS compacts have comparable CO 2 uptake (about 7.5 tons CO 2 /100 tons slag) and mechanically compressive strength values as those subjected to HP carbonation, suggesting that AP could be used to replace HP in carbonation curing to ensure a lower energy input. Additionally, AP seemed to possess as effective carbonation as HP. The studies investigated by multiple techniques including X-ray diffractometer (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopic analysis, and scanning electron microscopy (SEM) aim to identify the microstructure development of carbonated SS paste to assess carbonation results. Developed with life cycle assessment (LCA), environmental impact evaluation shows that AP presents a smaller global warming potential (GWP) value than HP. The comparable CO 2 sequestration, satisfactory engineering properties, enhanced microstructure and lesser environmental impact in AP carbonation confirm the feasibility of replacing high pressure with extremely low pressure to cure concrete products. The use of AP carbonation for cement material created using steel slag reduces carbon emissions, energy usage, and natural resource consumption., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Microbiologically influenced corrosion (MIC) behavior of the AISI 1020 carbon steel caused by consortia of nitrate-reducing prokaryotes (NRP) and sulfate-reducing prokaryotes (SRP) was investigated separately in hypersaline seawater conditions. Microbiological analysis, surface images, characterization of corrosion products, weight loss, and electrochemical measurements were employed to monitor the corrosion process for 10 days at 40 °C. Compared to abiotic corrosion (control), the extent of corrosion was more aggravated in the conditions with microbial consortia. It corroborates the critical role of microbial activity in corrosion processes in natural and industrial environments since microorganisms are widely spread. Corrosion rates obtained from Tafel extrapolation were statically equal for both microbial consortia (0.093 ± 0.009 mm.y -1 ); however, the maximum pit depth on the steel surface subjected to NRP-MIC was about 25% deeper (48.5 µm) than that caused by SRP-MIC (32.6 µm). In contrast, SRP activity almost doubled the number of pits on the steel surface (2.7 × 10 4  ± 4.1 × 10 3 pits.m -2 ), resulting in more weight loss than NRP activity. In addition, SRP cells formed nanowires to support direct electron uptake from steel oxidation. This research contributes to the understanding of steel corrosion mechanisms in hypersaline environments with the prevalence of NRP or SRP, as oil reservoirs undergo nitrate injection treatments., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The current study explores an artificial intelligence framework for measuring the structural features from microscopy images of the bacterial biofilms. Desulfovibrio alaskensis G20 (DA-G20) grown on mild steel surfaces is used as a model for sulfate reducing bacteria that are implicated in microbiologically influenced corrosion problems. Our goal is to automate the process of extracting the geometrical properties of the DA-G20 cells from the scanning electron microscopy (SEM) images, which is otherwise a laborious and costly process. These geometric properties are a biofilm phenotype that allow us to understand how the biofilm structurally adapts to the surface properties of the underlying metals, which can lead to better corrosion prevention solutions. We adapt two deep learning models: (a) a deep convolutional neural network (DCNN) model to achieve semantic segmentation of the cells, (d) a mask region-convolutional neural network (Mask R-CNN) model to achieve instance segmentation of the cells. These models are then integrated with moment invariants approach to measure the geometric characteristics of the segmented cells. Our numerical studies confirm that the Mask-RCNN and DCNN methods are 227x and 70x faster respectively, compared to the traditional method of manual identification and measurement of the cell geometric properties by the domain experts.

The acid treatment process of production wells is one of the most acid-induced corrosive processes. Corrosion inhibitors are an effective tool to inhibit the acids employed in acidizing treatments. Herein, new eco-friendly hydrazone-based compounds, namely, 2-(4-isobutylphenyl)- N -((1E,2E)-3-phenylallylidene) propanehydrazide (IPP) and N '-cyclohexylidene-2-[4-(2-methylpropyl)phenyl] propanehydrazide (CIP), were prepared through the functionalization of ibuprofen (IBF) and applied for corrosion mitigation of N80 steel in 15 wt % HCl (referred to hereafter as blank). The anticorrosion performance of selected compounds was investigated by employing weight loss (WL), potentiodynamic polarization curves (PPCs), and electrochemical impedance spectroscopy (EIS), complemented by scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses. In addition, density functional theory-based tight-binding (DFTB) modeling was conducted to get molecular-level insights into inhibitor-metal bonding. Experimental results revealed excellent long-term corrosion inhibition efficiency at very low concentrations of inhibitors and a mixed-type inhibition process. Numerically, N80 steel polarization resistance increased from 5.51 Ω cm 2 in blank to 608.4 and 396 Ω cm 2 in blank inhibited with 5 × 10 -3 mol/L of IPP and CIP, respectively, equivalent to 99% and 98% inhibition efficiency based on EIS experiments. Besides, SEM and AFM images showed that, after addition to 15 wt % HCl, inhibitors could effectively prevent the acid attack on the N80 steel surface. The fitting of experimental data to adsorption isotherms indicated that inhibitors' adsorption followed the Langmuir isotherm model and mixed physicochemical adsorption on the metal surface. The DFTB simulation revealed that inhibitor molecules can create covalent and physical interactions with iron atoms, which is further confirmed by partial density of states (PDOSs) analysis.

Offshore support structures and mooring systems are predominantly subject to corrosion and fatigue. These structures are typically covered with marine growth of various types. Conventional inspection methods for assessment of the structural integrity require access to the cleaned surface of these structures; however, the cleaning process is highly undesirable from the technical, economical, and environmental points of view. This paper highlights research on feasibility assessment of detection and localization of corrosion damage under marine growth using acoustic emission (AE). Experiments were conducted on two carbon steel plates, one baseline sample and one covered with artificially fabricated marine growth. The results of accelerated corrosion experiments suggest that corrosion-induced ultrasound signals can be detected with satisfactory signal-to-noise ratio using non-contact AE sensors. Ultrasound waves passing through marine growth showed around 12 dB drop in amplitude when compared to the base plate. A localization algorithm for corrosion induced-ultrasound signals was successfully implemented., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Phosphoric acid is the core material for the fertilizer industry; however, it is incredibly corrosive to manufacturing plants' structures, mainly steel. Corrosion is one of the most severe problems encountered during phosphate fertilizer manufacturing. Recently, plant extracts have been commonly used as corrosion inhibitors because they are cheap and environmentally friendly. Steel corrosion in a 20% aqueous phosphoric acid solution in the absence and presence of fenugreek seed (Fen) or cape gooseberry leaf (CgL) extracts was investigated using the electrochemical impedance spectroscopy technique, potentiodynamic polarization measurement, scanning electron microscope, and quantum chemical calculations. Fourier Transform Infrared, FTIR, was used to identify the functional groups in Fen and CgL extracts. The inhibition efficiency for steel in 20% aqueous phosphoric acid was roughly equal to 80% for 0.4 g/L CgL and 1.2 g/L Fen extracts. A scanning electron microscope showed that the chemical constituents of extracts block the surface roughness of steel, decreasing the corrosion rate. The activation parameters indicated the effectiveness of the extracts at a higher temperature. Measurements of the potential of zero charges showed that the steel surface is positively charged in the phosphoric acid solution. Quantum chemical computations were also employed to examine the corrosion inhibition mechanisms of the natural extracts., (© 2022. The Author(s).)

In this study, two types of Rare Earth (RE) 3-furoate complexes were synthesized by metathesis reactions between RE chlorides or nitrates and preformed sodium 3-furoate. Two different structural motifs were identified as Type 1RE and Type 2RE . The Type 1RE monometallic complexes form 2D polymeric networks with the composition [RE(3fur) 3 (H 2 O) 2 ] n ( 1RE = 1La, 1Ce, 1Pr, 1Nd, 1Gd, 1Dy, 1Ho, 1Y; 3furH = 3-furoic acid) while Type 2RE bimetallic complexes form 3D polymeric systems [NaRE(3fur) 4 ] n ( 2RE = 2Ho, 2Y, 2Er, 2Yb, 2Lu). The stoichiometric mole ratio used (RE: Na(3fur) = 1:3 or 1:4) in the metathesis reaction determines whether 1RE or 2RE (RE = Ho or Y) is formed, but 2RE (RE = Er, Yb, Lu) were obtained regardless of the ratio. The corrosion inhibition behaviour of the compounds has been examined using immersion studies and electrochemical measurements on AS1020 mild steel surfaces by a 0.01 M NaCl medium. Immersion test results revealed that [Y(3fur) 3 (H 2 O) 2 ] n has the highest corrosion inhibition capability with 90% resistance after 168 h of immersion. Potentiodynamic polarisation (PP) measurements also indicate the dominant behaviour of the 1Y compound, and the PP curves show that these rare earth carboxylate compounds act predominantly as anodic inhibitors.

Traditional corrosion inhibitors make great contribution to metal protection, but also cause environmental pollution. To solve the problem, plant extracts as green corrosion inhibitors have attracted much attention in recent years. Plants are good raw materials for corrosion inhibitors and also meet the requirements of industry. However, they have not been successfully applied in industry due to the unknown composition of the effective corrosion inhibitors and large dosage thereof. Therefore, cinchonain IIa was separated from Uncaria laevigata with abundant sources and low cost from nature in this work. Here we hypothesized that cinchonain IIa could show good corrosion inhibition performance for Q235 steel in the acidic medium. Through experiments and theoretical calculation, we studied the corrosion inhibition effect of cinchonain IIa on Q235 in 1 M HCl solution at 298 K for 48 h. Electrochemical experiments revealed that the inhibition efficiency of 200 mg/L cinchonain IIa in 1 M HCl for Q235 steel was 94.08% for 48 h. It even showed over 93% corrosion inhibition efficiency and durable protection performance to 28 d. Surface observations indicated that cinchonain IIa were firmly attached to the steel surface by forming a protective film. Moreover, quantum chemical calculation and molecular dynamics simulation revealed the inhibition mechanism at molecular and atomic level. Compared with some plant extracts, here we demonstrate that the outstanding advantages of cinchonain IIa include sustained protective effect, small dosage, and low toxicity. Accordingly, it may be used as a green industrial corrosion inhibitor with great potential in oilfield acidification and acid pickling., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Microbiologically influenced corrosion (MIC) is one of typical reasons leading to a lot of damage of pipeline steels in the shale gas environments. MIC behavior and mechanism studies are important towards to steel protection. In this work, Citrobacter amalonaticus, a corrosive bacterium, was isolated from a shale gas well of China. And the corrosion behavior of N80 steel caused by C. amalonaticus was studied in simulated shale gas produced water at 60 °C making use of weight loss, surface analysis, electrochemical impedance spectroscopy (EIS), anodic potentiostatic polarization measurements, and potentiodynamic polarization curves. Results demonstrate that C. amalonaticus could accelerate the uniform and localized corrosion rates of N80 steel at 60 °C with values of (0.221 ± 0.016) and (0.557 ± 0.062) mm/y, respectively. Experimental results suggested that the adsorption of an organic inhibitor film on steel surface caused the corrosion rates of abiotic specimens going down. However, the existence of C. amalonaticus inhibited the adsorption of organic inhibitor film. The adhesion and biofilm formation of C. amalonaticus contributed to steel corrosion acceleration. The nucleation and growth of metastable pitting were enhanced by C. amalonaticus, thus causing a severe localized corrosion., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The biological sulfur cycle is closely related to iron corrosion in the natural environment. The effect of the sulfur-oxidising bacterium Ectothiorhodospira sp., named PHS-Q, on the metal corrosion behaviour rarely has been investigated. In this study, the corrosion mechanism of Q235 carbon steel in a PHS-Q-inoculated medium is discussed via the characterization of the morphology and the composition of the corrosion products, the measurement of local corrosion and the investigation of its electrochemical behaviour. The results suggested that, initially, PHS-Q assimilates sulfate to produce H 2 S directly or indirectly in the medium without sulfide. H 2 S reacts with Fe 2+ to form an inert film on the coupon surface. Then, in localised areas, bacteria adhere to the reaction product and use the oxidation of FeS as a hydrogen donor. This process leads to a large cathode and a small anode, which incurs pitting corrosion. Consequently, the effect of PHS-Q on carbon steel corrosion behaviour is crucial in an anaerobic environment.

Searching for the efficient and sustainable inhibitors to defend metal corrosion in the marine environment has received a great deal attention in both academia and industry. In this work, a new strategy was developed to encapsulate benzimidazole (BI) inhibitor guest molecules into the micropores of bio-MOF-1, which was constructed with the other natural adenine inhibitor. Electrochemical characterizations revealed that the slowly sustained release of BI and adenine inhibitors from the BI@bio-MOF-1 composite presented excellent anti-corrosion durability in the whole mild steel corrosion process. The impedance arc value attained approximately 5000 Ω·cm 2 at initially 2 h and further increased to 6000 Ω·cm 2 after 5 days immersion in 0.5 M NaCl solution, and the inhibition efficiency reached 85.36% due to the synergistic dual inhibitive effect of BI@bio-MOF-1 composite. The dual inhibition-based bio-MOF-1 composite equipped strong metal-chelating capability and response durability, exhibiting high potentiality for metal anti-corrosion applications.

This study set out to determine the effectiveness of birch leaves extract (BLE) as a corrosion inhibitor against X52 pipeline steel in the pickling solution. Chemical and electrochemical techniques, as well as scanning electron microscope (SEM), Fourier-transform infrared (FT-IR), and adsorption isotherms were used in the research. Various triterpenoids, including betulin, betulinic acid, oleanolic acid, sitosterol, and kaempferol, are unquestionably involved in the corrosion inhibition mechanism, according to the high-performance-liquid-chromatography (HPLC) analysis. The 95% efficiency of the produced BLE extract (at optimum concentration 400 mg L -1 ) significantly reduced the corrosion rate of X52 pipeline steel in the pickling solution. The adsorption of BLE extract molecules on the X52-steel surface was demonstrated by SEM and FT-IR analysis. The adsorption activity follows the Langmuir adsorption theory., (© 2022. The Author(s).)

The development of the microbiologically influenced corrosion (MIC)-specific inductively coupled plasma-time of flight-mass spectrometry (ICP-ToF-MS) analytical method presented here, in combination with the investigation of steel-MIC interactions, contributes significantly to progress in instrumental MIC analysis. For this, a MIC-specific staining procedure was developed, which ensures the analysis of intact cells. It allows the analysis of archaea at a single cell level, which is extremely scarce compared to other well-characterized organisms. The detection method revealed elemental selectivity for the corrosive methanogenic strain Methanobacterium-affiliated IM1. Hence, the possible uptake of individual elements from different steel samples was investigated and results showed the cells responded at a single-cell level to the different types of supplemented elements and displayed the abilities to uptake chromium, vanadium, titanium, cobalt, and molybdenum from solid metal surfaces. The methods developed and information obtained will be used in the future to elucidate underlying mechanisms, compliment well-developed methods, such as SEM-EDS, and develop novel material protection concepts., (© The Author(s) 2022. Published by Oxford University Press.)

This work was focused on the rust conversion of proanthocyanidins (PC) for goethite (α-FeOOH), akaganeite (β-FeOOH) and lepidocrocite (γ-FeOOH), trying to show the potential of PC as an eco-friendly corrosion inhibitor and rust converter for archaeological steel conservation. The experiment used a rusted steel screw from Lingzhao Xuan of the Forbidden City in the Qing Dynasty and three kinds of pure iron oxyhydroxides as research samples. By means of micro-Raman, FTIR, XRD, XPS, SEM and EIS, PC had the ability to chemically react with iron oxyhydroxides in the rust, forming amorphous PC-FeOOH with a marked signal about 1384 cm -1 as phenolic-Fe in infrared properties. The original relatively stable iron oxides were not induced to phase transformation and still remained. The converted rust layer could be more stable in the corrosive medium and increased the corrosion potential more effectively. Both the rust layer resistance and the charge transfer resistance of the archaeological samples were improved by at least 3 times with 5.0 g/L of PC, which could reasonably stabilize the archaeological rust and hindered external corrosive penetration into the core. It was a mild protection material that showed satisfactory performance for archaeological steel cultural heritage and has a good application prospect.

In lubricated tribo-contacts, hydrogen ingress in steel is possible due to chemical reactions of lubricant components like base oils or additives, and/or contamination upon service particularly water, and/or corrosion processes, and/or electrostatic fields or current flow. Absorbed by the metal, atomic hydrogen may cause serious deleterious effects on the physical-chemical and mechanical properties, reducing the material's ability to withstand the design loads. The present research work is focused on analyzing the influence of electric field on lubricating oils in contact with steel surface. In order to evaluate the possibility of atomic hydrogen generation and permeation into the steel under cathodic polarization of lubricating oils the electrochemical permeation technique developed by Devanathan and Stachurski is used. The input cell of a Devanathan-Stachurski set up is appropriately modified by realizing a very close distance between the working electrode (steel membrane) and a Pt counter electrode with the oil between. This significantly increases the sensibility of the set up and allows the application of larger voltage and higher temperature to enable hydrogen generation from lubricating oils. The complex effects of cathodic polarization, temperature, additives and presence of water in model lubricating oils on atomic hydrogen permeation into steel is discussed., (© 2022. The Author(s).)

Green technology is a scientific movement seeking to eliminate industrial chemicals and replace them with natural products by valorizing natural resources or biological waste. In this work, we present the extraction of cellulose from rice straw and chemically modified water-dispersible cellulose (methylcellulose) by performing a methylation process. The methylcellulose is chemically bonded to N-[3-(trimethoxysilyl)propyl]ethylenediamine, and (3-aminopropyl)triethoxysilane compounds to produce a cellulose-organosilane hybrid. The prepared compounds were studied with appropriate techniques such as 1 H NMR, XRD, FTIR, TGA, Raman spectroscopy, FE-SEM, and AFM. The prepared materials were used as corrosion inhibitors of steel in 1 N H 2 SO 4 for studies of potentiodynamic polarization measurements and electrochemical impedance spectroscopy. The materials were also studied as antibacterial agents. The results indicate the successful use of a modified extracted cellulose hybrid in the corrosion field and as an antibacterial agent. Quantum chemical assessments based on density functional theory (DFT) of the trimethoxysilyl propylamine and dimethoxymethylsilyl propylethylenediamine grafted methylcellulose were calculated. The results obtained showed the agreement of the theoretical data with the experimental data., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The corrosion of industrial material is a costly problem associated with global economic losses reaching trillions of US dollars in the repair of failures. Injecting corrosion inhibitors is the most practically promising method for decelerating corrosion reactions and protecting surfaces. Recent investigations have focused on surfactants as corrosion inhibitors due to their amphiphilic nature, low cost, and simple chemical preparation procedures. This study aims to investigate the performance of an environment-friendly Quaternium-22 (Q-22) surfactant which is widely used in cosmetics for C-steel corrosion inhibition in a 5 M HCl medium. Weight loss experiments were performed at different concentrations and immersion times, presenting a maximum efficiency at 2.22 mmol·L -1 . The influence of Q-22 on the corrosion behavior of C-steel was elucidated using non-destructive electrochemical measurements. The overall results revealed that adding varied concentrations of Q-22 significantly decreases the corrosion rate of C-steel. The results revealed the physisorption nature of Q-22 onto the C-steel surface, with adsorption following the Freundlich isotherm (∆Hads= -16.40 kJ·mol - 1 ). The relative inhibition performance of Q-22 was also evaluated by SEM and AFM analyses. Lastly, quantum chemical calculations based on density functional theory (DFT) demonstrated that Q-22 has promising molecular features concerning the anticorrosive mechanism.

Inhibition of copper corrosion by some pyrimidinone derivatives, namely; (E)-N-(3-((1,3-dimethyl-2,4,6-trioxohexahydropyrimidin-5-yl)diazenyl)-2,5-diethoxyphenyl)benzamide (MA-975) and(E)-6-(4-((4-chlorophenyl)diazenyl)-3-methyl-5-oxo-4,5-dihydro-1H-pyrazol-1-yl)-1,3 dimethylpyrimidine-2,4(1H,3H)-dione (MA-978C) in 1.0 M nitric acid (HNO 3 ) was studied using weight loss (WL), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP) measurements. The efficiency of inhibition increases as the concentration of inhibitor increases, and it also increases as the temperature increases. With the addition of the examined inhibitors, significant corrosion protection was obtained, and (MA-975) showed a very promising % IE (89.59%) at 21 × 10 -6  M using the (WL) method. The polarization data revealed that these compounds act as mixed-type compounds and are adsorbed on the copper surface following Langmuir adsorption isotherm forming a protective thin film protecting the metal in the corrosive media. Scanning electron microscopy (SEM) and Energy Dispersive X-ray were used to examine the surface morphology of copper samples. Quantum calculations and Monte Carlo simulation techniques were applied with informative yields and the results matched the experimental findings., (© 2022. The Author(s).)

We report the synthesis of novel [4-(3-amino-4-mehoxy-5-methyl phenyl)-1-oxo-1H-phthalaz-2-yl] acetic acid hydrazide (APPH), followed by its characterization using X-ray diffraction (XRD), Fourier transforms infrared (FT-IR) spectroscopy, 1 H-NMR spectroscopy, and LC/MS. Further, the inhibition effect of the varying concentration of APPH on the corrosion of low steel (LCS) in 0.5 M H 2 SO 4 was investigated by weight loss and electrochemical measurements at 30 °C. The percentage inhibition efficacy of APPH increased with concentration and reached about 84% at 0.5 mM at 30 °C, also rising to 88% after 6 h of exposure. According to the polarization measurements, the investigated APPH works as a mixed-type inhibitor. Furthermore, the synergistic corrosion inhibition mechanism APPH showed that the inhibition efficiency maximizes with increasing inhibitor concentration, and the maximum value was 83% at 0.5 mM APPH. The adsorption of APPH on the LCS surface is more fitting to the Langmuir isotherm model. The free energy value (-ΔG° ads) was 33.3 kJ mol -1 . Quantum chemical calculation was applied to APPH and acted as excellent support for the experimental data., (© 2022. The Author(s).)

Nanoscale, localized corrosion underpins billions of dollars in damage and material costs each year; however, the processes responsible have remained elusive due to the complexity of studying degradative material behavior at nanoscale liquid-solid interfaces. Recent improvements to liquid cell scanning/transmission electron microscopy and associated techniques enable this first look at the nanogalvanic corrosion processes underlying this widespread damage. Nanogalvanic corrosion is observed to initiate at the near-surface ferrite/cementite phase interfaces that typify carbon steel. In minutes, the corrosion front delves deeper into the material, claiming a thin layer of ferrite around all exposed phase boundaries before progressing laterally, converting the ferrite to corrosion product normal to each buried cementite grain. Over the following few minutes, the corrosion product that lines each cementite grain undergoes a volumetric expansion, creating a lateral wedging force that mechanically ejects the cementite grains from their grooves and leaves behind percolation channels into the steel substructure.

Bridge steel structures are widely used in bridge construction with the advantages of light self-weight, convenient use, and good bridge span. Steel bridges are subjected to cyclic loading for a long time during their service period, and cyclic loading has a certain influence on their fatigue resistance performance. Fatigue is a phenomenon in which the structure is subjected to cyclic loading that generates cracks, expands continuously, and eventually leads to fracture of the member. The bridge steel structure under the repeated action of vehicle load and cyclic load is caused by microcracks and will expand with time, and the bridge deck system structure is prone to fatigue damage, so fatigue fracture detection has a great impact on the safe service life of steel bridges. In this paper, the fatigue design guidelines in the relevant codes and the bridge steel structure detection model are compared and analyzed, and a neural network-based fatigue fracture detection model for bridge steel structures under cyclic loading is proposed for the study of fatigue and corrosion interactions and fatigue and fracture of steel bridges under complex stress conditions. For this purpose, in the relevant experiments, experiments are designed to detect the fatigue fracture of bridge steel structures under different cyclic loads, and the experimental results prove the effectiveness of the proposed method., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2022 Dangfeng Yang et al.)

Carbon-steel pipelines have mostly been utilized in the oil and gas (OG) industry owing to their strength and cost-effectiveness. However, the detection of corrosion under coating poses challenges for nondestructive (ND) pipeline monitoring techniques. One of the challenges is inaccessibility because of the pipeline structure, which leads to undetected corrosion, which possibly leads to catastrophic failure. The drawbacks of the existing ND methods for corrosion monitoring increase the need for novel frameworks in feature extraction, detection, and characterization of corrosion. This study begins with the explanations of the various types of corrosion in the carbon-steel pipeline in the OG industry and its prevention methods. A review of critical sensors integrated with various current ND corrosion monitoring systems is then presented. The importance of acoustic emission (AE) techniques over other ND methods is explained. AE data preprocessing methods are discussed. Several AE-based corrosion detection, prediction, and reliability assessment models for online pipeline condition monitoring are then highlighted. Finally, a discussion with future perspectives on corrosion monitoring followed by the significance and advantages of the emerging AE-based ND monitoring techniques is presented. The trends and identified issues are summarized with several recommendations for improvement in the OG industry.

The steel slag was investigated for the removal of p-nitrophenol (4-NP) from simulated sewage by batch adsorption and fixed-bed column absorption experiments. The results showed that the maximum adsorption capacity was 109.66 mg/g at 298 K, pH of 7, initial concentration 100 mg/L, and dose 0.8 g/L. The adsorption process fitted the Langmuir isothermal adsorption model and followed pseudo-second-order kinetic models, the activation energy of adsorption (Ea) was 10.78 kJ/mol, which indicated that the adsorption was single-molecule layer physical adsorption. The regeneration efficiency was still maintained at 84.20% after five adsorption-desorption cycles. The column adsorption experiments showed that the adsorption capacity of the Thomas model reached 13.69 mg/g and the semi-penetrating time of the Yoon-Nelson model was 205 min at 298 K. Fe 3 O 4 was identified as the main adsorption site by adsorption energy calculation, XRD and XPS analysis. The FT-IR, Zeta potential, and ionic strength analysis indicated that the adsorption mechanism was hydrogen bonding interaction and electrostatic interaction. This work proved that steel slag could be utilized as a potential adsorbent for phenol-containing wastewater treatment., (Copyright © 2022 Elsevier Inc. All rights reserved.)

The present paper comprehensively investigates the complex interaction between ultrasonic guided waves and local structural discontinuities, such as damages, through highly sensitive features: so-called wave damage interaction coefficients (WDICs). These WDICs are unique for each structural discontinuity and depend solely on their characteristics for a given structure and condition. Thus, they can be particularly useful for advanced assessment of lightweight structures in the context of non-destructive evaluation and structural health monitoring. However, the practical application of WDICs entails significant difficulties due to their sensitivity and complex patterns. Therefore, this study attempts to guide researchers and practitioners in the estimation of WDICs from numerical simulations and physical experiments. Detailed investigations are made for an aluminum host plate modified by artificial structural discontinuities, i.e., surface-bonded steel sheets. The numerical simulations are performed to predict WDICs and study sensitivities using a sophisticated finite element model. The experimental setup uses piezoelectric transducers to excite guided waves in the host plate. A single scanning laser Doppler vibrometer measures the scattered guided waves caused by the surface-bonded steel sheets, and the resulting WDICs with possible influences are investigated. In both cases, the orientation and thickness of the attached steel sheets were varied to create 12 different damage scenarios. In general, the comparison between numerical and experimental WDICs show good agreement. This underpins the applicability of the general methodology for simulating and measuring WDICs over all scenarios. Furthermore, the WDIC scattering patterns reveal a clear dependency of the peaks in the back-scattered reflections for both the numerical and experimental amplitude coefficients on the damage orientation, basically following the law of reflection. However, some discrepancies between both studies were observed. Numerical sensitivity analysis identified the adhesive layer as one reason for such differences. Additionally, misalignment errors in the experimental measurements were also found to affect WDICs. Therefore, an improved baseline subtraction method is proposed, which clearly enhances the experimental WDICs. Finally, an experimental sensitivity study of WDICs for selected sensing radii revealed only a minor influence. All these investigations were made for the amplitude as well as the phase representation of WDICs. Thus, these findings may open the way to future research and development of techniques employing WDICs for advanced applications of non-destructive evaluation and structural health monitoring.

The corrosion inhibition of transition metal chelates derived from Schiff base ligands was tested for (mild, copper, stainless, aluminum and carbon) steel in various concentrations of (HCl, HNO 3 and H 2 SO 4 ) acidic medium at 25 °C through (weight loss, potentiodynamic polarization, polarization curves, electrochemical impedance spectroscopy (EIS) and open circuit potential measurements (OCP)) techniques. The studied compounds were identified with various spectral, analytical and physico-chemical techniques. It was observed that the investigated compounds had a significant inhibitory impact on the corrosion of diverse steels in the medium investigated. The analysis shows that increasing the dose of the studied complexes improves the corresponding inhibitory efficiency values. Negative results of Gibb's free adsorption energy (ΔGads0) prove the suppression process's spontaneous and physical adsorption, which contradicts the Langmuir adsorption isotherm. As a result of this insight, a novel bridge between nuclearity driven coordinated inorganic chemistry and materials, as well as corrosion control, has been built. This review provides an overview of the use of Schiff bases and associated transition metals as potential corrosion inhibitors, including the factors that influence their application.

The development of green corrosion inhibitors is a challenging task as it has to comply with strict environmental regulations. Ionic liquids (ILs) have recently been proposed as promising corrosion inhibitors. The present paper reports on two ILs designed to act as green and efficient high-temperature corrosion inhibitors. The prepared ILs, namely, choline formate (ChF) and choline acetate (ChA), are composed of biologically active ions. To elucidate their structure and corrosion inhibition effect on mild steel in 5% HCl the ILs were subjected to characterization tests like proton nuclear magnetic resonance ( 1 H NMR), carbon nuclear magnetic resonance ( 13 C NMR) and Fourier Transform infra-red (FT-IR) spectroscopy and corrosion tests like weight loss measurements, potentiodynamic polarization measurements (PDP), and electrochemical impedance spectroscopy (EIS). The effectiveness of the inhibition (%IE) increased with increasing concentrations and temperature up to 50 °C. ChF and ChA exhibited the highest inhibition efficacies of 96.9% and 99.5%, respectively at a temperature of 50 °C and concentration of 2 × 10 -3  M. Above 50 °C their inhibition performance diminished, displaying an efficacy of 77.6% for ChF and 79.3% for ChA at 80 °C. The results of polarization measurements suggested mixed type behavior of inhibitors, and adsorption followed Langmuir adsorption isotherm. Furthermore, surface studies like scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) revealed protecting capability of the investigated inhibitors. FT-IR, and Raman spectroscopic studies revealed the adsorption of ILs on the Fe surface, and an ultra-violet visible (UV-vis.) spectroscopy study confirms the formation of Fe 2+ - ILs complex. X-ray Photoelectron Spectroscopy (XPS) was conducted to study the formation of corrosion products and protective film over the mild steel surface. Density functional theory (DFT) calculations and molecular dynamics (MD) simulations were also done to understand the inhibition mechanism of ILs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Pyrimidine compounds have proven to be effective and efficient additives capable of protecting mild steel in acidic media. This class of organic compounds often functions as adsorption-type inhibitors of corrosion by forming a protective layer on the metallic substrate. The present study reports a computational study of forty pyrimidine compounds that have been investigated as sustainable inhibitors of mild steel corrosion in molar HCl solution. Quantitative structure property relationship was conducted using linear (multiple linear regression) and nonlinear (artificial neural network) models. Standardization method was employed in variable selection yielding five top chemical descriptors utilized for model development along with the inhibitor concentration. Multiple linear regression model yielded a fair predictive model. Artificial neural network model developed using k-fold cross-validation method provided a comprehensive insight into the corrosion protection mechanism of studied pyrimidine-based corrosion inhibitors. Using a multilayer perceptron with Levenberg-Marquardt algorithm, the study obtained the optimal model having a MSE of 8.479, RMSE of 2.912, MAD of 1.791, and MAPE of 2.648. The optimal neural network model was further utilized to forecast the protection capacities of nine non-synthesized pyrimidine derivatives. The predicted inhibition efficiencies ranged from 89 to 98%, revealing the significance of the considered chemical descriptors, the predictive capacity of the developed model, and the potency of the theoretical inhibitors., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Focused on the assessment of the diphenhydramine hydrochloride (DPH) capabilities as an alternative to conventional and harmful industrial corrosion inhibitors, electrochemical techniques were employed. The optimum concentration of 1000 ppm was determined by molecular simulation and validated through electrochemical experiments. The results acquired from the electrochemical impedance spectroscopy (EIS) study showed that DPH at a concentration of 1000 ppm has a corrosion efficiency of 91.43% after 6 h immersion. The DPH molecules' orientation on the surface was assessed based on EIS predicting horizontal adsorption on the surface. Molecular simulations were done to explore the adsorption mechanism of DPH. The DPH molecules' orientation on the surface was also assessed based on computational studies confirming the horizontal adsorption predicted by EIS., (© 2022. The Author(s).)

In this study, the anionic state of Ceftriaxone sodium (Cefx) and Ceftazidime (Cefz) medication corrosion inhibition capabilities for Al in 0.1 M NaOH solution are explored using various electrochemical analyses. Furthermore, the morphological structure and surface chemical composition of the impact of these drugs on the Al substrate in NaOH are investigated. For the prediction and analysis of interactions between molecule structure and inhibition efficiency, quantum chemical calculations (QC), Monte Carlo simulations (MC), and molecular dynamics (MD) simulations (MD) are performed. The electrochemical findings reveal that the inhibitory effectiveness increases with increasing drug concentrations and declines with rising temperature, reaching a maximum value of 78.4% for 300 ppm Cefx while 59.5% for 300 ppm Cefz at 293 K, implying that Cefx outperforms for Cefz. In addition, the studied drugs act as cathodic inhibitors, and their adsorption is spontaneous and mixed type adsorption in its nature that obeys Freundlich isotherm for Cefz while Temkin isotherm is the best-fitted one for Cefx. Surface analysis and wettability measurements imply that Cefx and Cefz shield the Al against corrosion by surface adsorption and generating a protective hydrophobic film. Thermodynamic activation parameters in the absence and presence of 300 ppm of the studied drugs are calculated and discussed. The energies of the border molecular orbitals and computed molecular parameters for the investigated drugs revealed that anionic Cefx is more readily adsorbed on the Al surface than Cefz. This finding is validated further using MC and MD simulations. Overall, the proposed cephalosporin drugs delivered a cost-effective and facile approach for boosting the efficiency of corrosion inhibitors for Al under aggressive conditions., (© 2022. The Author(s).)

The application of green and sustainable anticorrosive coatings is becoming of upsurge interest for the protection of metallic materials in aggressive environments. Herein, a stable crystalline chitosan/gum Arabic composite (CGAC) nanopowder was successfully synthesized and characterized by various methods. The CGAC nanopowder with different doses (25, 50, 100, and 200 ppm) was used to coat mild steel samples and examined its anticorrosion ability in 3.5 wt.% NaCl solution using gravimetric, electrochemical measurements, and surface characterization techniques. All methods yielded consistent results revealing that nanocomposite coatings can impart good anticorrosive properties to the steel substrate. The obtained protection efficiency was enhanced with increasing CGAC dose in the applied surface layer achieving 96.6% for the 200 ppm-coating. SEM and AFM surface morphologies of uncoated and coated samples after the inundation in the saline solution showed that CGAC coating can block the active corrosive sites on the steel surface, and prevent the aggressive Cl - ions from attacking the metallic substrate. The water droplet contact angle gave further support as it increased from 50.7° for the pristine uncoated surface to 101.2° for the coated one. The current research demonstrates a promising natural and reliable nanocomposite coating for protecting mild steel structures in the marine environment., (© 2022. The Author(s).)

In this study, the biofilms at different ages formed on galvanized steel coupons in a simulating cooling tower water system were exposed to the Ag-Cu ions over 504 h and the changes in the structure of the biofilms were investigated using electrochemical, microbiological, and surface analyses. The effect of the Ag-Cu ions on the structure of the natural biofilm during the maturation process was evaluated for the first time in this study. Exposure to Ag-Cu ions changed the structure of the biofilm, reducing the concentration of carbohydrates in EPS, causing the shedding from the biofilm by disrupting/making weakening the integrity of the biofilm. After exposure to Ag-Cu ions, the biofilm turned into a heterogeneous, fissured-porous and sandy structure. In addition, in the absence of the ions and after exposure to the ions, the MIC behavior of galvanized steel with natural biofilm at different ages was evaluated using electrochemical and gravimetric tests. It was determined that the galvanized steel suffered to MIC and exposure to Ag-Cu ions increased the corrosion rate of it. Therefore, using of Ag-Cu ions at maximum concentration values (0.1 ppm Ag and 1.3 ppm Cu) suggested by EPA is not recommended to prevent MIC problem in cooling tower systems., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Using traditional weight-loss tests, as well as different electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy), we investigated the corrosion-inhibition performance of 2,2′-(1,4-phenylenebis(methanylylidene)) bis(N-(3-methoxyphenyl) hydrazinecarbothioamide) (PMBMH) as an inhibitor for mild steel in a 1 M hydrochloric acid solution. The maximum protection efficacy of 0.0005 M of PMBMH was 95%. Due to the creation of a protective adsorption layer instead of the adsorbed H2O molecules and acidic chloride ions, the existence of the investigated inhibitor reduced the corrosion rate and increased the inhibitory efficacy. The inhibition efficiency increased as the inhibitor concentration increased, but it decreased as the temperature increased. The PMBMH adsorption mode followed the Langmuir adsorption isotherm, with high adsorption-inhibition activity. Furthermore, the value of the ∆Gadso indicated that PMBMH contributed to the physical and chemical adsorption onto the mild-steel surface. Moreover, density functional theory (DFT) helped in the calculation of the quantum chemical parameters for finding the correlation between the inhibition activity and the molecular structure. The experimental and theoretical findings in this investigation are in good agreement.

Steel corrosion is a global issue that affects safety and the economy. Currently, the homopolysaccharide (HoPS) structure of a novel lactic acid bacterium (LAB) is under study, as well as its application as a green corrosion inhibitor. Weissella cibaria FMy 2-21-1 is a LAB strain capable of producing HoPS in sucrose enriched media. The isolated and purified HoPS was characterized by different spectroscopic analyses as a linear α-1,6 dextran adopting a random coil conformation, with high molecular weight and extended size in water. The polysaccharide showed a semi-crystalline organization, which is a requirement for film formation. Its biocoating showed a grainy network structure, with a slightly lesser hydrophobic role in the aqueous environment than in the ionic one. The electrochemical measurements of the steel-HoPS coating showed that the biopolymer layer acts as an anodic-type corrosion inhibitor, with high resistance to corrosion by water and with chloride ions which prevent pitting, a corrosion process typical of bare steel. Few reports have cited the application of LAB HoPS as corrosive coating inhibitors. This work is the first to explore the influence of a structurally characterized dextran from Weissella cibaria strain as a potential steel corrosion inhibitor in ionic environments., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Steel is one of the mainly used materials in the oil and gas industry. However, it is susceptible to the marine corrosion, which 20% of the total marine corrosion is caused by microbiologically influenced corrosion (MIC). The economic and environmental impacts of corrosion are significant, and it is crucial to fight against corrosion in a proper sustainability context and environmental-friendly methods. In this study, the graphene oxide/silver nanostructure (GO-Ag) inhibitory effect on the corrosion of steel in the presence of sulfate reducing bacteria (SRB) was investigated, via weight loss (WL) and Tafel polarization measurements. Moreover, molecular dynamic (MD) simulations were performed to obtain a deep understanding of the corrosion inhibition effect of GO-Ag. GO-Ag showed a significant antibacterial effect at 80 ppm. Moreover, WL and Tafel polarization measurements illustrated a great inhibition efficiency, which reached up to 84% reduction of WL and 98% reduction of corrosion current density (I corr ) after 7 days of incubation with GO-Ag. Based on MD simulations, bonding energy reached to the larger value in the presence of GO-Ag, which indicated the ability of graphene oxide nanosheets to be adsorbed on the steel surface and prevent the access of corrosive agents to the steel surface. The radial distribution function (RDF) results implied distance between corrosive agent (water and SRB) and steel surface (Fe atoms), which indicated protection of the steel surface due to the effective adsorption of GO nanosheets through the active sites of the steel surface. The mean square displacement (MSD) result showed smaller displacement of the corrosive particles on the surface of steel, resulting that the GO-Ag molecules bonded with Fe molecules on the surface of steel., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Superhydrophobic coatings were successfully fabricated on steel substrates using potentiostatic electrodeposition of Ni and Ni-graphene, Ni-G, coatings followed by immersion in an ethanolic solution of stearic acid, SA. Rice straw, an environmentally friendly biomass resource, was used to synthesize high-quality graphene. The Raman spectra proved the high quality of the produced graphene. The Fourier transform infrared spectroscopy, FTIR, results showed that the Ni coating grafted with stearic acid, Ni-SA, and the Ni-G composite grafted with stearic acid, Ni-G-SA, were successfully deposited on the steel substrate. The scanning electron microscope, SEM, results showed that the prepared superhydrophobic coatings exhibit micro-nano structures. The wettability results revealed that the values of contact angles, CAs, for Ni-SA and Ni-G-SA coatings are 155.7° and 161.4°, while the values of sliding angles, SAs, for both coatings are 4.0° and 1.0°, respectively. The corrosion resistance, chemical stability, and mechanical abrasion resistance of the Ni-G-SA coating were found to be greater than those of the Ni-SA coating., (© 2022. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

An extract of cucumber leaves (ECSL) was prepared as a green corrosion inhibitor for carbon steel. Its carbon steel corrosion inhibition performance against 0.5 mol L -1 H 2 SO 4 was investigated using electrochemical methods and scanning electron microscopy (SEM). Its composition was analyzed by gas chromatography and mass spectroscopy (GC-MS). Quantum chemical calculations and molecular dynamics simulations (MDS) were conducted to elucidate the adsorption mechanism of the inhibitor molecules on the carbon steel surface. The results indicated that the inhibition efficiency increases with its increasing concentration. The extract acted as a mixed type corrosion inhibitor, and its inhibition properties were ascribed to the geometric coverage effect induced by its adsorption on the metal surface in accordance with Langmuir's law. The active components in the extract were identified as mainly organic compounds with functional groups such as aromatic moieties and heteroatoms. The inhibition activities of ECSL are delivered through the ability of the active components to adsorb on the metal surface through their functional groups to form a protective layer which hinders the contact of aggressive substances with carbon steel and thus suppresses its corrosion. This research provides an important reference for the design of green corrosion inhibitors based on plant waste materials.

Even with the exponential popularity of the contemporary clear aligners, the main stream of orthodontic practice still remains to be metal braces especially in adolescent age-group. 1 Along with the advantages of metal braces such as lower cost, reduced friction, etc., there goes the disadvantages such as corrosion possibility, reduced esthetics, etc. Corrosion of orthodontic appliances is a widely researched topic. 2-5 It is surprising to learn that microbially induced corrosion (MIC) has not been addressed in orthodontic literature till date. Microbial corrosion is an interesting arena which requires knowledge of both corrosion science and microbiology. The microorganisms capable of corrosion include various bacteria, fungi, and algae. The most common among them which has been widely indicated in MIC are the bacteria belonging to the sulfur cycle especially the sulfate-reducing bacteria (SRB). The connecting knot with orthodontics is the reported prevalence of these SRB in the oral cavity. SRB is prevalent in healthy individuals, 6,7 patients associated with periodontitis 6-11 and patients with gastrointestinal issues. 12-14 The prevalence of SRB in the oral cavity has a greater clinical implication since the SRB have been proven to cause corrosion of stainless steel. 15-24 There is literature attributing SRB as a potential cause in periodontal diseases 7-11 as well as gastrointestinal diseases such as ulcerative colitis, inflammatory bowel diseases, and Crohn's disease. 12 With its presence in the healthy oral environment already reported in the previous studies, 6,7,25,26 it further emphasizes the absolute need to be researching on its corrosion possibility in the intra oral environment. The genus generally found intraorally was Desulfovibrio and Desulfobacter 10 which is commonly regarded as the most "opportunistic" and ubiquitous group of sulfate reducers. 6,7 There is an interesting literature on the inhibition of Desulfovibrio spp. by human saliva, the reason being quoted as salivary nitrate and nitrite. 14 The mechanism behind the antimicrobial action of nitrate and nitrite is that they increase the oxidative stress on the bacteria. 27 However, concentrations of salivary nitrate vary depending on the food intake, endogenous production, and salivary flow rate. 28,29 Despite there exist natural inhibitors, the prevalence in oral cavity is high, 22% in healthy and 86% in patients associated with periodontitis. 7 There is a predilection for the bacteria to grow when favorable conditions exist. Biofilms is one such favorable medium for the growth of SRB. Paster et al. 26 identified SRB in biofilms of patients associated with refractory periodontitis, periodontitis, acute necrotizing ulcerative gingivitis (ANUG), and also in healthy subjects. Biofilm is a surface film composed of organic and inorganic saliva components that are colonized with microorganisms in extracellular polymeric substances adsorbed on all surfaces in the oral cavity. 30 The oral biofilm formation is a complex process involving interspecies aggregation, which is surrounded by a cohesive matrix, forms a complex structure which in turn facilitates anaerobic growth. It is the intrinsic nature of oral biofilms which make the survival of facultative anaerobes such as SRB in the oral cavity possible. Literatures 31-35 report that there are increased biofilm formations in orthodontic patients due to increased retentive areas caused by the brackets, ligatures, wires, mini implants, force components, and archwires. Bacteria in dental plaque function as a metabolically, functionally, and physically integrated community. 36 The study by Mystkowska et al. 37 mentioned that biofilm per se play a critical role in corrosion process by forming corrosive microcells. With time-dependent association, the microbes in the biofilm, along with saliva acting as an electrolyte and components from food, causes a decreased pH in the areas immediately under the biofilms. The decreased pH along with a change of oxygenation releases metal oxides and hydroxides from the metal surface ultimately leading to the corrosion of metallic structures. 37-41 The initial roughness also acts in a vicious form promoting more biofilm adherence and the process repeats causing more corrosion. With the biofilm itself serving to initiate and propagate corrosion, the increased prevalence of SRB in patients associated with orthodontics treatment all the more increases the possibility of MIC of orthodontic materials.

Bacillus licheniformis can take up electrons from X80 steel for nitrate reduction and accelerate corrosion. In this work, the routes B. licheniformis adopts for extracellular electron transfer (EET) were revealed using electrochemical tests, fluorescence staining, high performance liquid chromatography (HPLC) and weight loss tests, and their kinetics were also analyzed in detail. The results showed that B. licheniformis can take up electrons from steel surface via three routes: direct electron transfer by cytochromes, direct electron transfer by flavin-bound cytochromes and mediated electron transfer by diffusible flavin. B. licheniformis itself can only secrete traces of riboflavin which are mainly bound to the surface cytochromes assisting electron transfer. Adding flavins can increase the bound content, and with the binding sites of cytochrome becoming saturated the rest of flavins will mediate electron transfer through diffusion even more efficiently than the bound., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Steel slag is an industrial by product of steel manufacturing processes and has been widely utilized within civil and construction materials for road materials and environmental remediation in countries like Japan, USA, and European Union nations. However, the current utilization of steel slag in Vietnam is very low mainly because of lack of quality control of slag treatment and chances for reuse of treated steel slag. This paper presents the up to date steel slag production status in Vietnam through the extensive survey and sampling at seven large steel factories. The paper also highlights the environmental and quality control issues of these steel slags to use as road construction aggregates by assessing the heavy metals concentration in the leachate. The basic oxygen furnace (BOF) and electric arc furnace (EAF) slag samples were collected to evaluate leaching properties of metals leached from the slags. The two standardized batch leaching tests of steel slag roadbed material in Japan (JIS K 0058-1) and toxicity characteristics leaching procedure (TCLP-EPA method 1311) were performed to the evaluated the hazardous metals. The results of the leaching test show that almost all of the concentration of the metals in the leached solution does not exceed the National Standard for Industrial Wastewater Discharge (QCVN 40-2011). The pH and parameters such as total chromium, nickel, copper, lead, arsenic, and manganese differ from the two test methods. The acidic conditions employed in the EPA 1311 were not representative of condition excepted during slag reuse in road constructions because in the operation condition of the road, acidic liquid is absent. The leaching test results confirmed that JIS test which uses deionized water with gentle mixing prevents the slag sample from size degradation is suitable for the environmental assessment of steel slag use for roadbed material. This research suggests that the adjustment of pH value prior to disposal or reuse as base materials and official guideline should be promulgate by the authorities to ensure the leachate meet the surface water quality standard., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Biocides are often used to mitigate the microbially influenced corrosion (MIC) of construction materials in many fields. To study the effect of inadequate dosing of non-oxidizing biocide tetrakis (hydroxymethyl) phosphonium sulfate (THPS) on corrosion of pipeline steel caused by microorganisms, a novel marine isolate Desulfovibrio hontreensis SY-21 was selected as a test microorganism. Weight loss rate determination, morphological analyses, and corrosion product analyses combined with electrochemical measurements were performed to investigate the influence of THPS on the MIC of X70 pipeline steel. The responses of sessile and planktonic cells of D. hontreensis to THPS were also studied. Results showed that D. hontreensis cells could significantly promote steel corrosion and induce local corrosion pits. With a THPS addition within the tolerance range of D. hontreensis for the biocide, MIC of the steel was further promoted by 65%. The growth of planktonic cells was inhibited by the biocide, but the number of biofilm cells was significantly increased. This study revealed that THPS concentrations within a specific range increased the corrosive effect of the presence of D. hontreensis by promoting the growth of sessile cells and biofilm formation. Therefore, the use of the biocide in practical applications needs to be properly considered and managed., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The precipitation behavior of the MnS phase of MnO-SiO2 oxides in Si/Mn deoxidized steels was examined. MnS phase formation in the oxide phase was clearly identified, and the Mn content in both phases increased with isothermal holding at 1,200°C. With increased cooling rate, both the size of inclusions and the precipitation ratio of the MnS phase in the oxides decreased. More than 90% of MnO-SiO2 oxides contain MnS phases and MnS precipitation is accompanied by an Mn-depleted zone around the oxides. This zone was created not just around the MnS, but around the whole oxide inclusion. One can tentatively conclude that the majority of the MnS islands after isothermal holding are formed by the diffusion of Mn and S from the matrix into the inclusions. [ABSTRACT FROM AUTHOR]

In this study, the corrosion inhibition efficiency of thioridazine hydrochloride (TH), an antipsychotic drug, on mild steel (commonly used pipeline material in the oil and gas industry) in 1 M hydrochloric acid (HCl) was evaluated using electrochemical techniques and weight loss method. Electrochemical impedance spectroscopy (EIS) results suggest that TH significantly enhances the polarization resistance (R p ) of mild steel. Similarly, potentiodynamic polarization results showed that the corrosion current density (i corr ) of mild steel decreased significantly with addition of TH. To understand the long-term effect of TH, mild steel was tested for 7 days in 100 ppm TH containing electrolyte. EIS results showed that the R p did not change significantly after 24 h exposure as compared to 2 h exposure; whereas the R p increased by 28% after 7-day exposure. Weight loss measurements revealed that the inhibition efficiency of TH is remarkably high (98.8%) after 7-day exposure. The adsorption free energy calculation suggests that at the initial stage (1-day) of mild steel exposure, TH was physically adsorbed onto the surface. However, at a later stage (7- day) the binding of TH was chemical, and hence the corrosion protection increased with increase in the exposure period. As compared to the wide range of corrosion inhibitors reported in the literature, TH has shown to be highly effective for mild steel. Thus, it can be suggested that TH drug waste is a potential corrosion inhibitor for mild steel pipelines in the oil and gas industry., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A study of 250 commercial drugs to act as corrosion inhibitors on steel has been developed by applying the quantitative structure-activity relationship (QSAR) paradigm. Hard-soft acid-base (HSAB) descriptors were used to establish a mathematical model to predict the corrosion inhibition efficiency (IE%) of several commercial drugs on steel surfaces. These descriptors were calculated through third-order density-functional tight binding (DFTB) methods. The mathematical modeling was carried out through autoregressive with exogenous inputs (ARX) framework and tested by fivefold cross-validation. Another set of drugs was used as an external validation, obtaining SD, RMSE, and MSE, obtaining 6.76%, 3.89%, 7.03%, and 49.47%, respectively. With a predicted value of IE% = 87.51%, lidocaine was selected to perform a final comparison with experimental results. By the first time, this drug obtained a maximum IE%, determined experimentally by electrochemical impedance spectroscopy measurements at 100 ppm concentration, of about 92.5%, which stands within limits of 1 SD from the predicted ARX model value. From the qualitative perspective, several potential trends have emerged from the estimated values. Among them, macrolides, alkaloids from Rauwolfia species, cephalosporin, and rifamycin antibiotics are expected to exhibit high IE% on steel surfaces. Additionally, IE% increases as the energy of HOMO decreases. The highest efficiency is obtained in case of the molecules with the highest ω and Δ N values. The most efficient drugs are found with p K a ranging from 1.70 to 9.46. The drugs recurrently exhibit aromatic rings, carbonyl, and hydroxyl groups with the highest IE% values.

In this work, we found that the microbiologically influenced corrosion of Pseudomonas aeruginosa was mediated by Mo in low-alloy steel. Through immersion experiments, we found that the corrosion rate of low-alloy steel was not decreased with the addition of 1.0 wt% Mo. However, in the presence of P. aeruginosa, the corrosion rate of the 1.0 wt% Mo steel was accelerated, resulting in the development of pits. Confocal laser scanning microscopy images revealed that more biofilm cells adhered on the 1.0 wt% Mo steel surface. The chemotactic behavior and swimming ability of the bacteria were the main reason for the greater biofilm cell adhesion in the presence of Mo. Using an RNA-seq assay, we verified that both chemotaxis and motility together affected the adhesion of biofilm, and their related genes were affected by Mo., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Acid mine drainage is an extraordinarily acidic and highly heavy metal ion-contaminated leachate, seriously threatening the environment. In this work, an industrial solid waste of steel slag is the adsorbent to remediate the simulated acid mine drainage containing a large amount of Fe(II) ions. Due to the excellent physicochemical properties and structures, steel slag exhibited remarkable Fe(II) removal performance. Its maximum removal efficiency was up to 100%. The initial pH, the dosage and particle size of steel slag, and initial concentration of heavy metal ions on Fe(II) removal efficiency were determined. The pseudo-second-order model and Freundlich isotherm model well described the adsorption behavior of steel slag, implying that the adsorption of Fe(II) by steel slag was mainly multilayer chemisorption. The thermodynamic study demonstrated that the adsorption process was endothermic and spontaneous; the enthalpy change was calculated to equal 91.21 kJ/mol. Mechanism study showed that the entire removal process of Fe(II) by steel slag was completed by electrostatic adsorption, chemical precipitation, and surface complexation in cooperation, and the chemical precipitation was the dominant mechanism. Meaningfully, this study provides a valuable strategy and path for engineering applications of AMD remediation by steel slag, which is prospective as an ideal candidate for Fe(II) ions elimination, inspiring the future development of "Treating the wastes with wastes.", (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

One of the methods to improve the structural design of concrete is by updating the factors given in standard codes, especially when non-conventional materials are used in concrete beams. Accordingly, this study focuses on the colorations between the compressive strength and shear strength of high-strength concrete beams with and without steel fibers. For that purpose, different models are proposed to predict shear strength of high-strength concrete beams, by taking different combinations of the main variables: beam cross-section dimension (width and effective depth), reinforcement index, concrete compressive strength, shear span ratio, and steel fiber properties (volumetric content, fiber aspect ratio, and type of steel fibers). Multi-linear and non-linear regression analyses are used with large database experimental results found in the literature. The predicted results from the proposed equations are composed with different available models from codes, standards, and literatures. The calculated results showed better correlations and were close enough to the experimental data. Based on the data given in the standard codes, the shear strength is proportional to compressive strength ([Formula: see text]) of the power 0.5. However, this value may not be adequate for modern cement and concrete containing steel fibers. Therefore, the mentioned power value must be reduced 5 times to 0.1., Competing Interests: The authors have declared that no competing interests exist.

The production and use of eco-friendly corrosion inhibitors allows valuable compounds contained in plant waste to be identified and repurposed while reducing the use of polluting synthetic substances. Pectin extracted from Tahiti limes ( Citrus latifolia ) and King mandarin ( Citrus nobilis L.) in addition to natural gums-xanthan gum and latex from the "lechero" plant ( Euphorbia laurifolia )-were used to create an eco-friendly corrosion inhibitor. The optimal extraction conditions for pectin were determined from different combinations of pH, temperature, and time in a 2 3 factorial design and evaluated according to the obtained pectin yield. The highest pectin extraction yields (38.10% and 41.20% from King mandarin and lime, respectively) were reached at pH = 1, 85 °C, and 2 h. Extraction of pectic compounds was confirmed using Fourier-transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetry analyses. Subsequently, a simplex-centroid mixture design was applied to determine the formulation of extracted pectin and natural gums that achieved the highest corrosion inhibitor effect (linear polarization and weight loss methods in NACE 1D-196 saline media using API-5LX52 carbon steel). Impedance spectroscopy analysis showed that the addition of xanthan gum to pectin (formulation 50% pectin-50% xanthan gum) improved the corrosion inhibitor effect from 29.20 to 78.21% at 400 ppm due to higher adsorption of inhibitory molecules on the metal surface.