Search

Ca-Mg-Al hydrotalcites were prepared by coprecipitation from Type S95 steel slag of Shanghai Baosteel Group as supports of ionic liquid in this paper. Five basic ionic liquids [Bmim][CH 3 COO], [Bmim][HCOO], [Bmim]OH, [Bmim]Br and ChOH were prepared and their catalytic performance on the synthesis of glycerol carbonate by transesterification between dimethyl carbonate and glycerol was investigated. The characterization results indicated that [Bmim]OH is the best ionic liquid (IL) for the transesterification reaction of glycerol carbonate. The hydrotalcites before and after intercalation by ionic liquid were characterized by XRD, FTIR, SEM, EDS and the IL were characterized by FT-IR, 13 C-NMR and basicity determination via the Hammett method. The analysis results implied that the dispersion of [Bmim]OH in hydrotalcites reduced the alkali density appropriately and facilitated the generation of glycerol carbonate. The yield of glycerol carbonate and the conversion rate of glycerol reached 95.0% and 96.1%, respectively, when the molar ratio of dimethyl carbonate and glycerol was 3:1, the catalyst dosage was 3 wt%, the reaction temperature was 75 °C and the reaction time was 120 min. The layered structure of hydrotalcites increased the stability of ionic liquid intercalated in carriers, thus the glycerol conversion and the GC yield still remained 91.9% and 90.5% in the fifth reaction cycle.

The synergistic corrosion inhibition effect between calcium lignosulfonate (CLS) and three kinds of inorganic inhibitors (Na 2 MoO 4 , Na 2 SnO 3 , and NaWO 4 ) with various molar ratios on Q235 carbon steel in alkaline solution (pH 11.5) with 0.02 mol/L NaCl was investigated by cyclic potentiodynamic polarization, electrochemical impedance spectroscopy, linear polarization, scanning electron microscopy, and X-ray photoelectron spectroscopy. Molybdate and stannate in hybrid inhibitor could promote the passivation of steel and form a complex film, which could suppress the corrosion effectively. Moreover, the insoluble metal oxides in the complex film formed by three kinds of inorganic inhibitor could help the adsorption of CLS onto the steel surface. The CLS molecules could adsorb onto the steel surface and metal oxides to form an adsorption film to protect the steel from corrosion. A three-layer protection film formed by a hybrid inhibitor, including passivation film, deposition film, and adsorption film, would effectively inhibit the corrosion reactions on the steel surface. The CLS compound with molybdate with the ratio of 2:3 shows the best inhibition effect on both general corrosion and localized corrosion.

In the present study, different amounts, i.e., 1-3 v / v % of 1 M ammonium phosphate monobasic, were used as an eco-friendly corrosion inhibitor to mitigate the corrosion of steel rebar exposed to simulated concrete pore (SCP) + 3.5 wt% NaCl solution at a prolonged duration. Potentiodynamic polarization results show that as the amount of inhibitor is increased, the corrosion resistance of steel rebar is increased. The steel rebar exposed to 3% inhibitor-containing SCP + 3.5 wt% NaCl solution exhibited nobler corrosion potential ( E corr ), the lowest corrosion current density ( i corr ), and 97.62% corrosion inhibition efficiency after 1 h of exposure. The steel rebars exposed to 3% inhibitor-containing SCP + 3.5 wt% NaCl solution revealed higher polarization resistance ( R p ) and film resistance ( R o ) with exposure periods compared to other samples owing to the formation of passive film. The scanning electron microscopy (SEM) of steel rebar exposed to 3% inhibitor-containing SCP + 3.5 wt% NaCl solution showed homogenous and uniform dendritic passive film which covers all over the surface, whereas, bare, i.e., SCP + 3.5 wt% NaCl solution exposed samples exhibited pitting and irregular morphology. Raman spectroscopy results confirm the formation of goethite (α-FeOOH), maghemite (γ-Fe 2 O 3 ), and iron phosphate (FePO 4 ) as a passive film onto the steel rebar surface exposed to 3% inhibitor-containing SCP + 3.5 wt% NaCl solution. These phases are responsible for the corrosion mitigation of steel rebar which are very protective, adherent, and sparingly soluble.

Three anionic chitosan surfactant with different hydrophobic tails labeled Chitosan-R8, Chitosan-R12 and Chitosan-R16 were prepared and their surface behavior in aqueous solution was determined by surface tension measurements at three different temperatures 20, 40 and 60 °C. The affinity of the synthesized anionic chitosan surfactant to form micelle enhanced with increasing the hydrophobic chain length as well as raising the solution temperature up to 60 °C. The anionic chitosan surfactant showed a great influence as capping agent for the in-situ preparation of silver nanoparticles (AgNPs) based on photochemical reduction method using sunlight as reducing agent. The chemical structure of chitosan surfactant showed a great effect on the size and stability of the prepared AgNPs. The Chitosan-R16 with longer hydrophobic tail, produce a uniform, small size & stable AgNPs compared to shorter tail Chitosan-R12 & Chitosan-R8. The prepared anionic chitosan showed good inhibiting effect against the steel corrosion in the 1.0 M HCl. The corrosion inhibition efficiency was determined using three different techniques, proving the ability of the new chitosan surfactant to inhibit the steel corrosion. The XPS results confirmed the formation of chitosan inhibitor on the steel surface., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The deformation law for axisymmetric deformation during the drawing of a core filled tube (CORFT) has been studied. However, the results of such studies could not be used in the flat rolling process of the CORFT, which is a plan deformation condition. In this paper, the inner core material and outer steel tube were successively analyzed based on the slab method during the flat rolling process (plan deformation) of the CORFT, and equations for wall thickness, core density, and roll force have been developed. The theoretical results solved by the developed equations were compared with the experimental results, revealing adequate accuracy for engineering requirements. The influences of rolling parameters on the roll force and the ultimate value of the relative density of the core material were studied, and the limiting condition for a larger roll force or higher value for relative density was obtained., Competing Interests: The authors have declared that no competing interests exist.

Corrosion of carbon steel by microorganisms recovered from corroded seal rings at an offshore floating production facility was investigated. Microbial diversity profiling revealed that communities in all sampled seal rings were dominated by Pseudomonas genus. Nine bacterial species, Pseudomonas aeruginosa CCC-IOB1, Pseudomonas balearica CCC-IOB3, Pseudomonas stutzeri CCC-IOB10, Citrobacter youngae CCC-IOB9, Petrotoga mobilis CCC-SPP15, Enterobacter roggenkampii CCC-SPP14, Enterobacter cloacae CCC-APB1, Cronobacter sakazakii CCC-APB3, and Shewanella chilikensis CCC-APB5 were isolated from corrosion products and identified based on 16S rRNA gene sequence. Corrosion rates induced by the individual isolates were evaluated in artificial seawater using short term immersion experiments at 40 °C under anaerobic conditions. P. balearica, E. roggenkampii, and S. chilikensis, which have not been associated with microbiologically influenced corrosion before, were further investigated at longer exposure times to better understand their effects on corrosion of carbon steel, using a combination of microbiological and surface analysis techniques. The results demonstrated that all bacterial isolates triggered general and localised corrosion of carbon steel. Differences observed in the surface deterioration pattern by the different bacterial isolates indicated variations in the corrosion reactions and mechanisms promoted by each isolate.

The present study reports the synthesis, characterization and corrosion inhibition effects of chitosan (CH) and its 5-chloromethyl-8-hydroxyquinoline derivative (CH-HQ) for mild steel in acidic medium. The synthesized CH-HQ was characterized using 1 H NMR and FT-IR spectroscopic methods. Corrosion inhibition efficiencies of CH and CH-HQ were measured using electrochemical and chemical techniques. The surface protection ability of the inhibitor molecules was also ascertained by surface analysis, while computational study was used to further justify the adsorption tendencies of the molecules on mild steel surface. CH-HQwasobserved to exhibit better protection efficiency than CH, as the highest inhibition efficiencies were recorded to be 78% and 93% for CH and CH-HQ, respectively. Potentiodynamic polarization studies revealed that CH and CH-HQ are mixed-type corrosion inhibitors over the studied temperature range (298 K ± 1 to 328 K ± 1). SEM-EDS studies were performed to demonstrate the adsorption of CH and CH-HQ on the mild steel surface. Adsorption behavior of the CH and CH-HQ was also supported by UV-visible (UV-vis) spectrophotometric analyses. Monte Carlo simulations (MC) and density functional theory (DFT) calculations were carried out to corroborate the experimental results., Competing Interests: Declaration of competing interest The Authors declare that there is no any conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The Swiss disposal concept foresees that carbon-14 ( 14 C) is predominantly released from irradiated steel disposed of in a cement-based repository for low- and intermediate-level radioactive waste. To predict how 14 C migrates in the cementitious environment of the repository near field and subsequently in the host rock, knowledge about the carbon speciation during anoxic steel corrosion in alkaline conditions is therefore essential. To this end, batch-type corrosion experiments with carbon-containing zero-valent iron (ZVI) powders subject to oxidative pre-treatments were carried out in NaOH solution at pH 11 and 12.5. Alkanes and alkenes (C 1 -C 7 ) were identified in the gas phase and produced on the iron surface by a Fischer-Tropsch type mechanism. The kind of oxidative pre-treatment has an effect on the production rate of hydrocarbons (HCs). In the liquid phase, carboxylic acids were identified and produced during the oxidative pre-treatment of the ZVI powders. They are released instantaneously from the oxide layer upon contact with the alkaline solution. The kind of oxidative treatment and the exposure time to oxic conditions directly influence the amount of carboxylic acids accommodated in the oxide layer., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The influence of crude oil and chemical dispersant was evaluated over planktonic bacteria and biofilms grown on API 5L steel surfaces in microcosm systems. Three conditions were simulated, an untreated marine environment and a marine environment with the presence of crude oil and a containing crude oil and chemical dispersant. The results of coupon corrosion rates indicated that in the oil microcosm, there was a high corrosion rate when compared with the other two systems. Analysis of bacterial communities by 16S rRNA gene sequencing described a clear difference between the different treatments. In plankton communities, the Bacilli and Gammaproteobacteria classes were the most present in numbers of operational taxonomic unit (OTUs). The Vibrionales, Oceanospirillales, and Alteromonadales orders were predominant in the treatment with crude oil, whereas in the microcosm containing oil and chemical dispersant, mainly members of Bacillales order were detected. In the communities analyzed from biofilms attached to the coupons, the most preponderant class was Alphaproteobacteria, followed by Gammaproteobacteria. In the control microcosm, there was a prevalence of the orders Rhodobacterales, Aeromonadales, and Alteromonadales, whereas in the dispersed oil and oil systems, the members of the order Rhodobacterales were present in a larger number of OTUs. These results demonstrate how the presence of a chemical dispersant and oil influence the corrosion rate and bacterial community structures present in the water column and biofilms grown on API 5L steel surfaces in a marine environment. KEY POINTS: • Evaluation of the effects of oil and chemical surfactants on the corrosion of API 5L. • Changes in microbial communities do not present corrosive biofilm on API 5L coupons.

The rapid degradation of marine infrastructure at the low tide level due to accelerated low-water corrosion (ALWC) is a problem encountered worldwide. Despite this, there is limited understanding of the microbial communities involved in this process. We obtained samples of the orange-colored tubercles commonly associated with ALWC from two different types of steel sheet piling, located adjacent to each other but with different levels of localized corrosion, at a seaside harbor. The microbial communities from the outer and inner layers of the orange tubercles and from adjacent seawater were studied by pure culture isolation and metabarcoding of the 16S rRNA genes. A collection of 119 bacterial isolates was obtained from one orange tubercle sample, using a range of media in anaerobic and aerobic conditions. The metabarcoding results showed that sulfur and iron oxidizers were more abundant on the outer sections of the orange tubercles compared to the inner layers, where Deltaproteobacteria (which include many sulfate reducers) were more abundant. The microbial communities varied significantly between the inner and outer layers of the orange tubercles and also with the seawater but overall did not differ significantly between the two steel sheet types. Hence, we saw similar microbial communities in orange tubercles present, but different levels of localized corrosion, for two different types of colocated steel sheet piling. Metallurgical analysis found differences in composition, grain size, ferrite-pearlite ratio, and the extent of inclusions present between the two steel types investigated. IMPORTANCE The presence of orange tubercles on marine steel pilings is often used as an indication that accelerated low-water corrosion is taking place. We studied the microbial communities in attached orange tubercles on two closely located sheet pilings that were of different steel types. The attached orange tubercles were visually similar, but the extents of underlying corrosion on the different steel surfaces were substantially different. No clear difference was found between the microbial communities present on the two different types of sheet piling. However, there were clear differences in the microbial communities in the corrosion layers of tubercles, which were also different from the microbes present in adjacent seawater. The overall results suggest that the presence of orange tubercles, a single measurement of water quality, or the detection of certain general types of microbes (e.g., sulfate-reducing bacteria) should not be taken alone as definitive indications of accelerated corrosion., (Copyright © 2020 American Society for Microbiology.)

Oil palm frond (OPF) is one of largest contributions to the biomass waste from oil palm plantation. In this work, OPF has been successfully utilized to prepare cellulose nanocrystal (OPF-CNC) by acid hydrolysis. OPF was initially treated with autohydrolysis treatment. The obtained OPF-CNC was characterized via complementary analyses. The produced OPF-CNC showed a high crystallinity index value (60%) and high BET surface area (26.10 m 2  g -1 ) as compared to α-cellulose (crystallinity index: 54% and BET surface area:7.14 m 2 g -1 ). The surface analyses via scanning electron microscope (SEM) and transmission electron microscopy (TEM) demonstrated that the OPF-CNC has a smooth surface with a needle-like shape, where the average length and diameter are 95.09 nm and 6.81 nm, respectively. The corrosion analyses via electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PD) illustrate that the coated mild steel with the inclusion of 0.5 wt% OPF-CNC has managed to sharply reduce the corrosion (99%). The coated mild steel with the inclusion of 0.5 wt% OPF-CNC showed the highest hydrophobicity (100.5 ± 0.7°) and has lowest amount of O via water contact angle and energy dispersive X-ray spectroscopy (EDX) analyses respectively, indicating lowest corrosion rate., (Copyright © 2020 Elsevier B.V. All rights reserved.)

An effective and biodegradable polygonatum fructan (PF) from Polygonatum cyrtonema Hua was studied as an eco-friendly corrosion inhibitor for mild steel protection in 1 M HCl, whose inhibition performance was studied by weight loss tests, electrochemical techniques, and surface analysis techniques (SECM, FTIR). The experimental results showed that PF has outstanding inhibition performance for mild steel in hydrochloric acid, and the inhibition efficiency increased with the increase of its concentration and temperature. Polarization studies indicated that PF is a mixed-type corrosion inhibitor, and its adsorption mode conforms to Langmuir isotherm, mainly chemisorption. An adsorption-related protective inhibitor film formed on the surface of mild steel was verified and investigated based on its surface analysis and characterization. Quantum chemical analysis showed that the adsorption of PF on the surface of mild steel has obvious chemical properties., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Two drugs (cefpirome, cefixime) as dual-action inhibitors could self-organize on copper surface forming bio-functional protective film, which effectively prevents copper corrosion in the picking process with an excellent performance on the resistance of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) results showed that studied drugs can self-organize on copper surface successfully forming adsorption film to protect copper. The results also indicated that N/S atoms with the lone pair electrons in the drugs donated electrons to the vacant orbital of Cu occupying the active sites of copper surface. Electrochemistry and surface morphology study revealed that the corrosion inhibition efficiency of cefixime was better than cefpirome. Furthermore, adsorption isotherm study suggested that the adsorption was spontaneous chemical and physical adsorption, obeying Langmuir adsorption., Competing Interests: Declaration of Competing Interest I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for publication elsewhere. All the authors listed have approved the manuscript that is enclosed. To the best of our knowledge, the named authors have no conflict of interest, financial or otherwise., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Chitosan was chemically functionalized using aminotriazolethiol in a facile single-step synthesis. The macromolecule was evaluated as an inhibitor for corrosion of stainless steel in 3.5% NaCl solution. A detailed electrochemical investigation employing electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) was performed, which showed that the inhibitor acts by adsorption on the steel surface and shows a mixed type behavior with the prevalence of cathodic behavior. The new inhibitor aminotriazolethiol-modified chitosan (ATT-Cht) exhibited excellent water solubility and behaved as an efficient inhibitor against corrosion of stainless steel in 3.5% NaCl showing a corrosion inhibition efficiency of 97.8% at a concentration as low as 100 mg L -1 . The results of surface studies using scanning electron microscopy along with energy dispersive X-ray spectroscopy supported the adsorption of the inhibitor on the steel surface., (Copyright © 2020. Published by Elsevier B.V.)

The main studies on the corrosion of metals induced by microorganisms are directed only to the surface of the metal, without considering the presence of welds between these surfaces. For this reason, we evaluated the difference of microbial community grown in carbon steel coupons, and two different types of welds, E7018 and Tungsten electrodes, exposed under simulated microcosm. After 30 days, they were recovered, the biofilms scraped and the microbial communities analyzed by 16S rRNA gene sequencing. The results showed that there was a differentiated distribution among the three samples collected. Proteobacteria phylum composed most of the species described in all samples. At the class level, Gammaproteobacteria was the most detected, followed by Alphaproteobacteria and Flavobacteriia. The most prevalent order was Alteromonadales, which was present in Weld2, followed by Rhodobacteriales, which was more prevalent in Fe1020 and Weld1. The orders Cytophagales, Sphingomonadales, and Burkholderiales were described in higher number in Fe1020, whereas Oceanospirillales, Thiotrichales, Flavobacteriales, Rhodospirillales, and Kordiimonadales were higher in samples Weld1 and Weld2. The analyses between the three evaluated conditions show the presences of bacterial groups preferred by different types of metal, suggesting that approaches in the control of biocorrosion should take into account the chemical composition of the metal.

In this work, the microbial corrosion inside a perforation on an X52 pipeline steel was investigated in wet soil containing sulfate-reducing bacteria (SRB) by biotesting, electrochemical measurements, including open-circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization, and surface analysis techniques such as 3D topographic imaging, scanning electron microscopy and energy-dispersive x-ray spectrum. Results show that the further corrosion rate of the initial perforation on pipelines is not uniform along its depth direction, and the corrosion kinetics depends on the availability of microorganism such as SRB in the environment. In abiotic environments, the perforation close to the solution side corrodes more rapidly than that at the soil side. However, in SRB-containing environments, the corrosion kinetics is different, where the middle of perforation possesses the greatest corrosion rate, which is attributed to the microbially accelerated corrosion. There are generally more sessile SRB cell counts on the steel near the solution phase than that at the soil side. The corrosion of the perforation could be attributed to the high counts of sessile SRB cells and their starvation effect, making the SRB extract electrons directly from the steel., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier B.V. All rights reserved.)

This paper investigates the development of the alkalinity and its impact on carbon steel reinforcement embedded in alkali-activated fly ashes (AAFA) and alkali-activated fly ashes with ten percentage mass (wt%) of blast furnace slag (AAFAS)-based materials (geopolymer-GP). The pH analysis of eluates indicates a remarkable decrease of alkalinity in AAFA and AAFAS in the first hours of the geopolymerization process. Phenolphthalein solution and pore solution tests on concretes also show a sharp decrease of alkalinity with increased Ca content in the binder due to carbonation. Micro X-ray computer tomography (µXCT) and electrochemical techniques indicate that the changed pH in the GP systems was accompanied by a decrease in the corrosion rates of steel reinforcement when compared to ordinary Portland cement (OPC) systems. In contrast to calcite and vaterite, which were detected in OPC and AAFAS after a carbonation process, only sodium carbonate natron was determined at lower levels in AAFA by X-ray diffraction (XRD).

The major focus of the recent studies in metals corrosion protection field is now the development of non-hazardous and eco-friendly materials as effective substitutes for some of the well-known conventional toxic/unsafe inhibitors based on chromate, lead, phosphate, and azole derivatives. The present work focuses on the sustainable development of an intelligent self-healing anticorrosion coating using nanocarriers based on the graphene oxide nanoplatform-Tamarindus indiaca extract-Zn 2+ (GON-Ti.E-Zn)-through a facile green assisted route. The GON-Ti.E-Zn nanocarrier was introduced into the epoxy ester film (EEF) to achieve a smart barrier/self-healing anti-corrosive property. To this end, a couple of characterization tests, including FT-IR, UV-vis, XRD, TGA, and Raman spectroscopy, have been carried out to investigate the GON-Ti.E-Zn nanocarrier structure/composition. The effectiveness of the anti-corrosion performance of the established coatings was confirmed by EIS, FE-SEM, and accelerated salt spray (SS) test. The observation of the high impedance magnitude at low-frequency (47.14 Gohm cm 2 after 5 weeks immersion in saline solution) for the un-defected EEF and significant impedance enhancement for the defected EEF including GON-Ti.E-Zn nanocarrier confirmed the excellent barrier effect of GO and synergistic behavior and noticeable corrosion inhibition impact of Tamarindus indiaca along with the zinc cations on the mild steel corrosion mitigation., 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 © 2020 Elsevier B.V. All rights reserved.)

New thin BiVO 4 film using facile water‒based electrophoretic deposition process was synthesized on the webbed stainless steel surface. This work can be considered as a green method owing to use of safe, non-flammable, and cheap media of water as solvent of electrophoretic deposition. Structural and morphological properties of the resultant film were studied by X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy (SEM), Elemental and Mapping analyses (EDS), Optical Microscopy, Atomic Force Microscopy (AFM), and X-ray Photoelectron Spectroscopy (XPS) analysis. The moderate diameter size of nanorods of the deposited BiVO 4 was measured in the range of 100 to 150 nm. The prepared three layered thin film was shown permanent photocatalytic degradation rate of Amoxicillin pharmaceutical pollution as high as 97.45 % after 90 min. It can be suggested that BiVO 4 nanorods have the high ability of hole-electron separation and electron transferring through the alternative routes. Indeed, the prepared thin films of BiVO4 having nanoroad morphology possess great potential for light harvesting. Moreover, webbed stainless steel with electron acceptor character leads to severe separation of photogenerated hole‒electron. The mechanistic study of the scavenging reaction introduced the hydroxyl radicals as the main specie in the photocatalytic process. It is interesting that obtained results of photocatalytic process of this BVO film within different pollutants (dyes, phenol, and drugs) demonstrated the high efficiency and mineralization rate., 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 © 2019 Elsevier B.V. All rights reserved.)

The corrosion behaviour of X80 pipeline steel was studied in a simulated marine environment inoculated with marine bacterium Marinobacter salsuginis. The electrochemical results showed that the increase in linear polarization resistance, charge transfer resistance, and the decrease in corrosion current density of the X80 pipeline steel immersed in the biotic medium indicated its high corrosion resistance compared to those in the abiotic medium. Surface morphological techniques including scanning electron microscopy, confocal laser scanning microscopy and live/dead cells staining were employed to observe the biofilm morphology and bacterial viability after different immersion times. X-ray photoelectron spectroscopy was used to analyse the oxides film formed on the steel surface. The obtained results indicated that the corrosion inhibition efficiency was obviously higher in the biotic medium compared to that in the abiotic medium. The high corrosion resistance of X80 steel in biotic medium was attributed to the formation of biofilm and the development of extracellular polymeric substances (EPS) layer on its surface., (Copyright © 2020 Elsevier B.V. All rights reserved.)

With the increase in iron/steel production, the higher volume of by-products (slag) generated necessitates its efficient recycling. Because the Linz-Donawitz (LD) slag is rich in silicon (Si) and other fertilizer components, we aim to evaluate the impact of the LD slag amendment on soil quality (by measuring soil physicochemical and biological properties), plant nutrient uptake, and strengthens correlations between nutrient uptake and soil bacterial communities. We used 16 S rRNA illumine sequencing to study soil bacterial community and APIZYM assay to study soil enzymes involved in C, N, and P cycling. The LD slag was applied at 2 Mg ha -1 to Japonica and Indica rice cultivated under flooded conditions. The LD slag amendment significantly improved soil pH, plant photosynthesis, soil nutrient availability, and the crop yield, irrespective of cultivars. It significantly increased N, P, and Si uptake of rice straw. The slag amendment enhanced soil microbial biomass, soil enzyme activities and enriched certain bacterial taxa featuring copiotrophic lifestyles and having the potential role for ecosystem services provided to the benefit of the plant. The study evidenced that the short-term LD slag amendment in rice cropping systems is useful to improve soil physicochemical and biological status, and the crop yield.

China has the largest share of global iron and steel production, which is considered to play a significant contribution to air pollution. This study aims to investigate trace element contamination at different fractions of particulate matter (PM) at industrial areas in China. Three PM fractions, PM2.1-9.0, PM1.1-2.1 and PM1.1, were collected from areas surrounding iron and steelmaking plants at Kunming, Wuhan, Nanjing and Ningbo in China. Multiple trace elements and their bioavailability, as well as Pb isotopic compositions, were analysed for identification of contaminants, health risk assessment and source apportionment. Results showed that PM particles in the sites near industrial areas were associated with a range of toxic trace elements, specifically As, Cr(VI), Cd and Mn, and posed significant health risks to humans. The isotopic Pb compositions identified that coal and high temperature metallurgical processes in the steelmaking process were the dominant contributors to local air pollution in these sites. In addition to iron and steelmaking activities, traffic emissions and remote pollution also played a contributing role in PM contamination, confirmed by the differences of Pb isotopic compositions at each PM fraction and statistical results from Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE) and Geometrical Analysis for Interactive Aid (GAIA). The results presented in this study provide a comprehensive understanding of PM emissions at iron and steelmaking areas, which helps to guide subsequent updates of air pollution control guidelines to efficiently minimise environmental footprint and ensure long term sustainability of the industries., Competing Interests: The authors have declared that no competing interests exist.

Bacillus widely exists in wet natural environment such as soil, water and air, and is often studied as one of representative microorganisms for microbiologically influenced corrosion(MIC) research. In this paper, the growth curve of Bacillus subtilis isolated from marine environment was determined by turbidimetry and its effect on corrosion behavior of 10MnNiCrCu steel was studied by open circuit potential, AC impedance, polarization curve and scanning electron microscopy(SEM). The results showed that with the change of the growth curve of Bacillus subtilis(BS), the open circuit potential(E ocp ) shifted positively and then negatively, and the charge transfer resistance shown by AC impedance was much lower than that of the sterile system, increasing first and then decreasing. The polarization curves showed that the corrosion current density in BS medium was obviously higher than that in sterile system. The corrosion morphology observation showed that although a biofilm by BS developed on the steel surface, the localized corrosion of 10MnNiCrCu steel was aggravated due to the acidness of the metabolite itself and the biofilm with access for electrolyte ions.

Investigation of carbon steel corrosion influenced by in-situ microbial communities can provide reliable information about microbiologically influenced corrosion (MIC) in the oil and gas field. Here, we investigated the 90-day corrosion behavior of Q235 carbon steel influenced by interior deposit microflora of an in-service pipeline using open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS). Linear sweep voltammetry (LSV), 16S rRNA gene sequencing, and surface analysis were used to comprehensively analyze the corrosion mechanisms. The results indicated that OCP was decreased while the charge transfer resistance (R ct ) was increased, and that steel corrosion was inhibited during the first 45 days. Subsequently, OCP was significantly increased while R ct was rapidly decreased, and steel corrosion was enhanced. After 90-day immersion, severe pitting corrosion with a maximum pit depth of 89.6 μm occurred on the steel surface. Viable microbes in the final biofilm significantly increased the cathodic current. Iron carbonate, chukanovite and cementite were identified as the main corrosion products on the steel surface. Methanobacterium dominated the final biofilm community. These observations indicate that the corrosion mechanism of the final biofilm can be explained by extracellular electron transfer MIC in which microbes corrode steel by direct electron uptake., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interests., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The impact that nutrient level has on biofilm characteristics, biocide effectiveness, and the associated risk of microbiologically influenced corrosion (MIC) was assessed using multispecies biofilms from two different oilfield consortia. A range of microbiological, microscopy, and corrosion methods demonstrated that the continuous flow of nutrients for the microbial growth resulted in higher activity, thickness, and robustness of the biofilms formed on carbon steel, which induced greater localized corrosion compared to biofilms formed under batch, nutrient-depleted conditions. Despite of the differences in biofilm characteristics, biofilms displayed comparable susceptibilities to glutaraldehyde biocide, with similar log 10 reductions and percent reductions of microorganisms under both nutrient conditions. Nevertheless, nutrient replenishment impacted the effectiveness of the biocide in controlling microbial populations; a higher concentration of cells survived the biocide treatment in biofilms formed under a continuous flow of nutrients. Complementary DNA-/RNA-based amplicon sequencing and bioinformatics analysis were used to discriminate the active within the total populations in biofilms established at the different nutrient conditions and allowed the identification of the microbial species that remained active despite nutrient depletion and biocide treatment. Detection of persistent active microorganisms after exposure to glutaraldehyde, regardless of biofilm structure, suggested the presence of microorganisms less susceptible to this biocide and highlighted the importance of monitoring active microbial species for the early detection of biocide resistance in oil production facilities. IMPORTANCE Microbiologically influenced corrosion (MIC) is a complex process that generates economic losses to the industry every year. Corrosion must be managed to prevent a loss of containment of produced fluids to the external environment. MIC management includes the identification of assets with higher MIC risk, which could be influenced by nutrient levels in the system. Assessing biofilms under different nutrient conditions is essential for understanding the impact of flow regime on microbial communities and the subsequent impact on microbial corrosion and on the effectiveness of biocide treatment. This investigation simulates closely oil production systems, which contain piping sections exposed to continuous flow and sections that remain stagnant for long periods. Therefore, the results reported here are useful for MIC management and prevention. Moreover, the complementary methodological approach applied in this investigation highlighted the importance of implementing RNA-based methods for better identification of active microorganisms that survive stress conditions in oil systems., (Copyright © 2020 Salgar-Chaparro et al.)

Frost damage of concrete has significant effects on the safety and durability of concrete structures in cold regions, and the concrete structures after repair and reinforcement are still threatened by cyclic freezing and thawing. In this study, the new-to-old concrete interface was reinforced by steel bar. The shear strength of the new-to-old concrete interface was tested after the new-to-old combination was subjected to cyclic freeze-thaw. The effects of the diameter of the steel bar, the compressive strength of new concrete, the number of freeze-thaw cycles and the freezing temperatures on the shear properties of new-to-old concrete interface were studied. The results showed that, in a certain range, the shear strength of the interface was proportional to the diameter of the steel bar and the strength of the new concrete. Meanwhile, the shear strength of the reinforced interface decreased with the decreasing of the freezing temperature and the increasing of the number of freeze-thaw cycles.

Biological process is an important and integral part of the coke plant wastewater treatment. Increasing pressure to meet more stringent discharge limits has led to adopt tertiary treatment for biologically treated coke plant (BTCP) effluent which contains intense colour along with many residual toxic pollutants like phenol, cyanide, thio-cyanate and COD. A sustainable process has been developed to remove these pollutants from BTCP effluent by using an indigenous material coke breeze which is abundantly available in integrated steel plant. Based on the developed process, a full-scale (200 m 3 /h) treatment plant has been designed for installation. The designed data has been obtained from a continuous demo plant treating 10 m 3 /h BTCP effluents. The utilised coke breeze is entirely used for sinter making. The process is highly efficient for the removal of colour above 95% and other residual pollutants like phenol, cyanide and COD to a safe level for discharge or reuse. This process neither incurs any additional chemical cost nor generates any secondary pollutants or products. Moreover, the developed process is very sustainable as it has some great advantages like less investment and low maintenance cost; therefore, the method is good in economics. The treated wastewater contains very less amount of chemical residues therefore meets the standards for reuse as industrial water resource. Hence, this developed technology has significant economic, social and environmental benefits. Graphical Abstract .

The present investigation devices a novel X-type six-high (X-6h) mill. In addition, parametric models of different roll layouts such as the four-high (4-h), I-type six-high (I-6h), and X-6h mills are established. Three-dimensional (3D) finite element (FE) contact analysis for a strip rolling process is conducted when the mills are subjected to a constant vertical load of 65 kN. Through comparative analysis of von Mises stress, contact stress and elastic deformation displacement in three roll layouts, the rigidity characteristic of each is obtained, and it is found that the proposed X-6h mill has the largest roll gap stiffness. The influence of different roll diameter ratios on the roll gap stiffness of the roll system is investigated, based on which an optimization design model is built. Further, by taking into account the roll gap stiffness of the roll system as the optimization objective, the optimum diameter ratios of backup roll (BUR) to work roll (WR) of the X-6h rolling mill is achieved via the genetic algorithm (GA) optimization method, obtaining the optimum structural parameters of BUR and WR as well. The reliability of the proposed design is verified by manufacturing a prototype mill which produced magnesium alloy and aluminum alloy strips of high quality., Competing Interests: The authors have declared that no competing interests exist.

This work reports on the preparation and systematic testing of a novel multi-layered coating, comprised of the non-steroid anti-inflammatory drug diclofenac and biopolymer carboxymethyl cellulose. Drug release testing was performed on an Automated Transdermal Diffusion Cells Sampling System in combination with UV-VIS spectroscopy as the released drug concentration determination method. The results showed that most of the drug is released in the first six hours, whereas the overall released amount could be tailored through changes in the multi-layered coating composition. Biocompatibility tests performed on human osteoblast cells, showed cell viability improvement between 7% and 17% compared to the control sample. The expression of proteins playing important roles in extracellular matrix production and functioning was performed in order to obtain additional proof of the prepared materials' osteointegration boosting capacity. Finally, electrochemical measurements confirmed that the coatings do not influence the corrosion susceptibility of AISI 316LVM stainless steel., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Waste management and global warming are the two challenging issues of the present global scenario. Increased human population has set the platform for rapid industrialization and modern agriculture. The industries such as energy, steel, and fertilizers play a significant role in improving the social, and economic status of human beings. The industrial production of energy (that involves combustion of coal), production of steel items and diammonium ammonium fertilizer generate a huge amount of wastes such as fly ash (FA), steel slag (SS) and phosphogypsum (PG), respectively. Inappropriate dumping of any kind of waste poses a threat to the environment, therefore, scientific management of waste is required to reduce associated environmental risks. These wastes i.e. SS, FA, and PG being rich sources of oxides of calcium (CaO), silicon (SiO 2 ), iron (FeO), and aluminum (Al 2 O 3 ), etc. may affect the release of greenhouse gases from the soil. The information associated with the application of FA, SS, and PG onto the paddy fields and their impacts on methane and nitrous oxide emissions are highly fragmented and scarce. The present review extensively and critically explores the available information with respect to the effective utilization of FA, SS, and PG in paddy cultivation, their potential to mitigate greenhouse gases emission and their associated mechanisms. The fine grid assessment of these waste management provides new insight into the next level research and future policy options for industries and farmers., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

High concentration of nitrogen and phosphorus and imbalance of N/P can lead to the formation of water and the malignant proliferation of toxic microalgae. This study put forward the advanced nutrient removal with the regulation of effluent N/P as the core in order to restrain the eutrophication and growth of poisonous algae. According to the preliminary study and review, the optimal N/P for non-toxic green algae was 50:1. The horizontal sub-surface flow constructed wetland was filled with steel slag and ceramsite to achieve the regulation of effluent N/P. The results showed that steel slag had the stable P removal capacity when treating synthetic solution with low P concentration and the average removal rate for 1.5, 1.0, and 0.5 mg/L synthetic P solution was 2.98 ± 0.20 mg kg -1 /h, 2.26 ± 0.15 mg kg -1 /h, and 1.11 ± 0.10 mg kg -1 /h, respectively. Combined with P removal rate and P removal task, the filling amount of steel slag along the SSFCW (sub-surface flow constructed wetland) was 3.22 kg, 4.24 kg, and 4.31 kg. In order to ensure the stability of dephosphorization of steel slag, the regeneration of P removal capacity was investigated by switching operation of two parallel SSFCW in 20 days for cycle. The N removal was limited for the deficiency of carbon source (COD (chemical oxygen demand)/TN = 3-4), and was stable at 18.5-31.9% which was less affected by temperature. Therefore, by controlling the process of quantitative P removal of steel slag, the effluent N/P in SSFCW can be stable at 40-60:1 in the whole year, so as to inhibit the malignant proliferation of toxic algae.

An eco-friendly Schiff base, namely Salicylaldeyde-Chitosan Schiff Base (SCSB), was synthesized by the reaction of chitosan and salicylaldehyde. In 3.5% NaCl saturated with carbon dioxide at 65 °C corrosion inhibition effect was analyzed using weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods. The PDP results revealed that SCSB acts as a mixed type inhibitor and reduces the corrosion process effectively at 150 mg L -1 concentration with an inhibition efficiency of 95.2% and corrosion rate of 0.444 mm/y. EIS measurements suggest that the corrosion inhibition process is kinetically controlled. Langmuir adsorption model is the best fit among the other tested isotherms. The surface analysis was carried out using scanning electron microscopy (SEM), atomic force microscopy (AFM), scanning Kelvin probe (SKP), and X-ray photoelectron spectroscopy (XPS) to corroborate the formation of inhibitor film on the metal surface. Computational studies showed the effective adsorption of the protonated form of inhibitor., (Copyright © 2019 Elsevier B.V. All rights reserved.)

It is recognized that interactions between most materials are governed by their surface properties and manifest themselves at the interface formed between them. To gain more insight into this thin layer, several methods have been deployed. Among them, spectroscopic methods have been thoroughly evaluated. Due to their exceptional sensitivity, data acquisition speed, and broad material tolerance they have been proven to be invaluable tools for surface analysis, used by scientists in many fields, for example, implant studies. Today, in modern medicine the use of implants is considered standard practice. The past two decades of constant development has established the importance of implants in dentistry, orthopedics, as well as extended their applications to other areas such as aesthetic medicine. Fundamental to the success of implants is the knowledge of the biological processes involved in interactions between an implant and its host tissue, which are directly connected to the type of implant material and its surface properties. This review aims to demonstrate the broad applications of spectroscopic methods in implant material studies, particularly discussing hard implants, surface composition studies, and surface-cell interactions., Competing Interests: The authors declare no conflict of interest.

This study aims at finding a suitable alternative for traditional and hazardous organic/inorganic corrosion inhibitors. In this study, the aqueous extract of Esfand seed (ESE) was used as a unique green source of nitrogen-based organic compound with great capability of the steel corrosion inhibition in a saline solution. Surface and electrochemical analyses were carried out by Ultraviolet-visible spectroscopy (UV), Fourier-transform infrared spectroscopy (FT-IR), Grazing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS), and polarization methods. Furthermore, the adsorption of inhibitors on the steel surface was explored by Monte Carlo (MC), molecular dynamics (MD) and quantum mechanics (QM) methods. The electrochemical studies established the effectiveness of the zinc cations addition to the ESE containing solution on its inhibition efficiency. The sample inhibited by 300 ppm ESE + 700 ppm Zn showed the highest anti-corrosion properties. The inhibition efficiency of this sample was reached 98.8% after 264 h which is much higher than those reported in the previous studies. QM computations proved the formation of complexes via donor-acceptor action. MC and MD simulations supported the inhibitors adsorption on the steel., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The characteristic changes in steelmaking slag and humic acids (HAs) derived from a slag-compost fertilizer and their relation to the elution of Fe were evaluated in tank tests in Mashike, Hokkaido and Tsushima, Nagasaki. Analyses of iron, nitrogen and phosphate in the eluate, changes in the chemical states on the surface of the steelmaking slag, and the macro-structural features of the isolated HAs were investigated during the test. Temporal changes in Fe concentrations in the tanks were consistent with data collected in previous studies. Analyses of the surface by 57 Fe Mössbauer spectroscopy showed that the concentration of Fe 2+ in the fertilizer decreased and the ratio of Fe 3+ increased, indicating that Fe 2+ was preferentially eluted from the slag surface. The yields of HAs were significantly decreased during the test when steelmaking slag was mixed with compost. Changes in the UV-vis absorptivities indicated that de-aromatization had occurred. These results indicate that microorganisms that were present under these experimental conditions became activated by the mixing of compost with steelmaking slag, and are closely related to the continuous elution of Fe. The residual Fe in the fertilizer after the tests was investigated by analyzing seawater and the levels of extractable Fe. The trends for extractable Fe concentrations were consistent with the results obtained by 57 Fe Mössbauer spectroscopy and UV-vis spectra.

We present a combined experimental and theoretical study of the effective corrosion protection of carbon steel in 1 M HCl solution by Phellodendron chinense Schneid (PCS) bark extract. Fourier-transform infrared spectroscopy (FTIR) and liquid chromatography tandem multi-stage mass spectrometry (LC-MS n ) were employed for the extract characterization. The properties of PCS as a corrosion inhibitor were evaluated by electrochemical and gravimetric experiments. Quantum chemical calculation was used to describe the electronic and adsorption properties of the identified and characterized compounds found in the extract while molecular dynamics simulation was employed to predict the equilibrium configurations and binding energies of the compounds on the steel surface. The electrochemical results revealed that PCS acted as a mixed-type corrosion inhibitor whose efficiency increased with the extract concentration but slightly decreased with increasing temperature. Quantum chemical parameters, such as the energy difference (ΔE) and the number of transferred electrons (ΔN), were used to predict the contribution of each characterized compound to the inhibition process while molecular dynamics simulation predicted parallel orientations for the configuration of the compounds and high binding energies on the metal substrate., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The inhibition effect of the invasive brown seaweed Sargassum muticum extract (ESM), harvested from the Atlantic coast of Morocco, against the corrosion of carbon steel (CS) in 1 M HCl medium was studied for the first time using gravimetric, electrochemical and surface techniques. The methanolic crude extract of Sargassum muticum (ESM) is rich in alginate biopolymer. The evaluation corrosion tests showed that this algal extract acts as a good mixed corrosion inhibitor for CS substrate in 1 M HCl since inhibition efficiency of 97% was reached with 1 g/L of ESM at 303 K. AC impedance findings showed that the seaweed extract adding in the corrosive electrolyte increases the polarization resistance and conversely decreases the charge capacitance at the interface. Adsorption of ESM on the substrate surface followed the Langmuir adsorption isotherm. X-ray photoelectron spectroscopy analyses (XPS) demonstrated that the corrosion inhibition mechanism of CS substrate in 1 M HCl environment by the investigated algal extract is typical of the chemisorption process and the protective barrier is mainly formed by the adsorbed biological macromolecules., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Eucalyptus leaves extract (ELE) inhibition impact toward mild steel (MS) corrosion in the HCl solution was examined by combined experimental and computational studies. The degree of inhibition was investigated by EIS and polarization test. The EIS analysis results showed that the increase of ELE concentration led to the significant increment of charge transfer resistance. An inhibition efficiency of ~88% was obtained using 800 ppm ELE after 5 h exposure. Polarization test results indicated the mixed inhibition effects of ELE with slight cathodic prevalence. The i corr values for the uninhibited and inhibited (800 ppm ELE) samples were 0.93 μA/cm 2 and 0.25 μA/cm 2 , respectively. The ELE molecules adsorption on the surface of MS followed a Langmuir isotherm. Furthermore, the molecular simulation results evidenced the adsorption of ELE compounds on the iron surface., (Copyright © 2019. Published by Elsevier B.V.)

In this paper, we demonstrate an innovative electromagnetic targeting system utilizing a passive magnetic-flux-concentrator for tracking endobronchoscope used in the diagnosis process of lung cancer tumors/lesions. The system consists of a magnetic-flux emitting coil, a magnetic-flux receiving electromagnets-array, and high permeability silicon-steel sheets rolled as a collar (as the passive magnetic-flux-concentrator) fixed in a guide sheath of an endobronchoscope. The emitting coil is used to produce AC magnetic-flux, which is consequently received by the receiving electromagnets-array. Due to the electromagnetic-induction, a voltage is induced in the receiving electromagnets-array. When the endobronchoscope's guide sheath (with the silicon-steel collar) travels between the emitting coil and the receiving electromagnets-arrays, the magnetic flux is concentrated by the silicon-steel collar and thereby the induced voltage is changed. Through analyzing the voltage-pattern change, the location of the silicon-steel collar with the guide sheath is targeted. For testing, a bronchial-tree model for training medical doctors and operators is used to test our system. According to experimental results, the system is successfully verified to be able to target the endobronchoscope in the bronchial-tree model. The targeting errors on the x -, y - and z -axes are 9 mm, 10 mm, and 5 mm, respectively., Competing Interests: The authors declare no conflict of interest

Chitosan is one of the important natural bio-polymers. Besides its good green value, it is rarely used to protect metals in aggressive media in direct form due to rapid degradation of its molecules in acid. Hence, it is necessary to use some means to increase protection efficiency of chitosan. In present work, cobalt and tin sulfide nanoparticles are used to synthesize chitosan-cobalt and chitosan-SnS 2 nanocomposites, and used for corrosion protection of mild steel (MS) in 1 M HCl at room temperature. The prepared composites are investigated by UV-visible spectroscopy, FTIR spectroscopy, HRSEM, HRTEM and EDAX techniques, which have shown successful formation of nanocomposites. Corrosion behavior of the composites have been examined by Tafel polarization curves (TPC), single sine electrochemical impedance spectroscopy (SSEIS) and surface analyzing techniques. The results have declared that chitosan-cobalt nanocomposite is more effective in corrosion inhibition of mild steel than chitosan-SnS 2 nanocomposite. Alone chitosan provide only 77% inhibition to mild steel, while it increases for chitosan‑cobalt (>95%) and chitosan-SnS 2 (>80%) composites. Isotherm study suggests that adsorption of chitosan/composites over MS is main reason of inhibition and can be best defined with Frumkin isotherm. Adsorption of chitosan and chitosan-nanocomposites over MS is also evident by SEM and AFM., (Copyright © 2019 Elsevier B.V. All rights reserved.)

To investigate morphological characteristics and generation mechanism of the machined gears surface, image characteristics of machined surface morphology including profile roughness, fractal and textural characteristics were studied. the change of profile curves for the surface image is subject to the normal probability density function and the W-M function. The orientation angle of surface texture is 0°, the surface profile curves are the smoothest and have the most uniform, regular textures. When the texture orientation is 45° or 135°, the surface profile curves show large fluctuations, while surface image textures present the deepest grooves and are shown to be distributed most irregularly. Additionally, the influence mechanism of different grinding parameters on the morphological characteristics of machined surface was investigated. The quality of machined surfaces increased with the grinding speed while deteriorated with increasing radial, or axial, feed speeds., Competing Interests: The authors have declared that no competing interests exist.

A simple, low-cost, fluorine-free, and ecofriendly method was applied to prepare a novel superhydrophobic Zn-Fe alloy coating on the surface of carbon steel. First of all, the Zn-Fe coating was obtained in an alkaline glycerol non-cyanide Zn-Fe plating solution. Then tetradecanoic acid was grafted onto the Zn-Fe coating by a coordination reaction, leading to a superhydrophobic surface. The water contact angle was up to 166° and the sliding angle was 4°. The as-prepared superhydrophobic coating exhibited high performances, such as strong adhesion to the substrate, impact resistance, self-cleaning, antifouling, and anticorrosion. Importantly, until now, few reports focus on the use of a non-cyanide alkaline glycerol plating bath for electrodeposition, which is green, composition-stable, and corrosion-free for devices. In addition, the growth mechanism of the Echinopsis multiplex -like hierarchical micro/nanostructure of the superhydrophobic surface was studied in detail.

While Fe-based alloys have already been reported to possess all mechanical properties required for vascular stenting, their relatively low degradation rate in vivo still constitutes their main bottleneck. The inflammatory reaction generated by a stent is inversely proportional to its mass. Therefore, the tendency in stenting is to lower the section so to reduce the inflammatory reaction. Twinning-induced plasticity steels (TWIP) possess excellent mechanical properties for envisaging the next generation of thinner degradable cardiovascular stents. To accelerate the degradation, the addition of noble elements was proposed, aimed at promoting corrosion by galvanic coupling. In this context, silver was reported to generally increase the degradation rate. However, its impact on the deformation mechanism of TWIP steels has not been reported yet. Results show that the use of Ag significantly reduces the ductility without altering the strength of the material. Furthermore, the presence of Ag was found to promote a different deformation texture, thus stimulating the formation of mechanical martensite. Since a stent works in the deformed state, understanding the microstructure and texture resulting from plastic deformation can effectively help to forecast the degradation mechanisms taking place during implantation and the expected degradation time. Moreover, knowing the deformed microstructure allows to understand the formability of very small tubes, as precursors of the next generation of thin section degradable stents. STATEMENT OF SIGNIFICANCE: Commercial degradable magnesium stents are limited from their relatively big structure size. Twinning-induced plasticity steels possess outstanding mechanical properties, but their degradation time goes beyond the timeframe expected from clinics. The inclusion of noble Ag particles, which favor galvanic coupling, is known to promote corrosion and solve this limitation. However, it is necessary to understand the impact that Ag has on the deformation microstructure and on the mechanical properties. The addition of Ag reduces the ductility of a twinning-induced plasticity steel because of a different deformation microstructure. Since a stent works in a deformed state inside an artery, understanding the microstructural evolution after plastic deformation allows to better predict the device performances during service life., (Copyright © 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Electrochemical, anticorrosion and adsorption behaviour of bio-based melatonin (MEL) in 5% HCl solution was investigated by experimental and theoretical approaches. MEL was found to possess high adsorptive capacity for steel surface and inhibits the acid corrosion. With a concentration of 10 mM, inhibition efficiency of 98.3% and 88.6% were obtained at 30 °C and 60 °C respectively. Langmuir associative and dissociative models describe simultaneous physisorption and chemisorption. FTIR, SEM/EDS and quantum molecular dynamics simulations using DFT provide evidences that MEL forms adsorbed surface complex film (in the protonated form) coordinated mainly by indole ring, N(9) and O(10). The biomolecule is a promising alternative anticorrosion additive for acid wash solutions., (Copyright © 2019. Published by Elsevier B.V.)

Steel marine structures provide foci of biodiversity when they develop into artificial reefs. Development begins with deposition of a biofilm. The effects of contaminants from oil spills on biofilm microbiomes, microbially-induced corrosion (MIC) and metal loss may impact preservation of marine metal structures. A microcosm experiment exposed biofilms on carbon steel disks (CSDs) to crude oil, dispersant, and dispersed oil to address their impacts on bacterial composition and metal loss and pitting. Biofilm diversity increased over time in all exposures. Community composition in dispersant and dispersed oil treatments deviated from the controls for the duration of a 12-week experiment. As biofilms matured, Pseudomonadaceae increased while Rhodobacteraceae decreased in abundance in dispersed oil treatments compared to the controls and dispersant treatments. Greatest mass loss and deepest pitting on CSDs were observed in dispersed oil treatments, suggesting impacts manifest as a consequence of increased MIC potential on carbon steel.

This paper investigates anticorrosion behaviour of the bark-extract from Rhizophora mangle L. on steel-rebar in concrete slabs in 3.5% NaCl medium of immersion (for simulating saline/marine environment). Corrosion-rate, corrosion-current, and corrosion-potential were measured from the NaCl-immersed steel-reinforced concrete cast with admixture of different plant-extract concentrations and from positive control concrete immersed in distilled water. Analyses indicate excellent mathematical-correlation between the corrosion-rate, concentration of the bark-extract admixture, and electrochemical noise-resistance (ratio of the corrosion-potential standard deviation to that of corrosion-current). The 0.4667% Rhizophora mangle L. bark-extract admixture exhibited optimal corrosion-inhibition performance, η = 99.08±0.11% (experimental) or η = 97.89±0.24% (correlation), which outperformed the positive control specimens, experimentally. Both experimental and correlated results followed Langmuir adsorption isotherm which suggests prevalent physisorption mechanism by the plant-extract on the reinforcing-steel corrosion-protection. These findings support Rhizophora mangle L. bark-extract suitability for corrosion-protection of steel-rebar in concrete structure designed for immersion in the saline/marine environmental medium., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this paper.

Friction stir spot welding (FSSW), a derivative of friction stir welding (FSW), is a solid-state welding technique that was developed in 1991. An industry application was found in the automotive industry in 2003 for the aluminum alloy that was used in the rear doors of automobiles. Friction stir spot welding is mostly used in Al alloys to create lap joints. The benefits of friction stir spot welding include a nearly 80% melting temperature that lowers the thermal deformation welds without splashing compared to resistance spot welding. Friction stir spot welding includes 3 steps: plunging, stirring, and retraction. In the present study, other materials including high strength steel are also used in the friction stir welding method to create joints. DP780, whose traditional welding process involves the use of resistance spot welding, is one of several high strength steel materials used in the automotive industry. In this paper, DP780 was used for friction stir spot welding, and its microstructure and microhardness were measured. The microstructure data showed that there was a fusion zone with fine grain and a heat effect zone with island martensite. The microhardness results indicated that the center zone exhibited a greater degree of hardness compared with the base metal. All data indicated that the friction stir spot welding used in dual phase steel 780 can create a good lap joint. In the future, friction stir spot welding can be used in high-strength steel welding applied in industrial manufacturing processes.

Community compositional changes and the corrosion of carbon steel in the presence of different electron donor and acceptor combinations were examined with a methanogenic consortium enriched for its ability to mineralize paraffins. Despite cultivation in the absence of sulfate, metagenomic analysis revealed the persistence of several sulfate-reducing bacterial taxa. Upon sulfate amendment, the consortium was able to couple C28H58 biodegradation with sulfate reduction. Comparative analysis suggested that Desulforhabdus and/or Desulfovibrio likely supplanted methanogens as syntrophic partners needed for C28H58 mineralization. Further enrichment in the absence of a paraffin revealed that the consortium could also utilize carbon steel as a source of electrons. The severity of both general and localized corrosion increased in the presence of sulfate, regardless of the electron donor utilized. With carbon steel as an electron donor, Desulfobulbus dominated in the consortium and electrons from iron accounted for ∼92% of that required for sulfate reduction. An isolated Desulfovibrio spp. was able to extract electrons from iron and accelerate corrosion. Thus, hydrogenotrophic partner microorganisms required for syntrophic paraffin metabolism can be readily substituted depending on the availability of an external electron acceptor and a single paraffin-degrading consortium harbored microbes capable of both chemical and electrical microbially influenced iron corrosion., (© FEMS 2019.)

An effective and biodegradable Ficus tikoua leaves extract was studied as a corrosion inhibitor for carbon steel in hydrochloric acid. Systematic electrochemical experiments and morphological characterization were carried out to investigate the properties of the corrosion inhibitor. Meanwhile, quantum chemical calculations were performed to aid further understanding of the electrochemical mechanism. The electrochemical results reveal that the extract inhibitors act as a mixed-type with an inhibition efficiency up to 95.8% at 298 K. Moreover, this extract shows good inhibory activity at a wide range of temperatures and the corresponding results were further confirmed by morphological analysis. The chemical formulae of these major components are fully optimized in the DFT with B3LYP in the gas phase and the base set is 6-311++G (d, p)., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Although marine biofouling has been widely studied on different substrates, information on biofouling on plastics in the Arabian Gulf is limited. Substrate- and location-specific effects were investigated by comparing the microbial communities developed on polyethylene terephthalate (PET) and polyethylene (PE) with those on steel and wood, at two locations in the Sea of Oman. Total biomass was lower on PET and PE than on steel and wood. PET had the highest bacterial abundance at both locations, whereas chlorophyll a concentrations did not vary between substrates. MiSeq 16S ribosomal RNA sequencing revealed comparable operational taxonomic unit (OTU) richness on all substrates at one location but lower numbers on PET and PE at the other location. Non-metric multidimensional scaling (NMDS) showed distinct clusters of the bacterial communities based on substrate (analysis of similarity (ANOSIM), R = 0.45-0.97, p < 0.03) and location (ANOSIM, R = 0.56, p < 0.0001). The bacterial genera Microcystis and Hydrogenophaga and the diatoms Licmophora and Mastogloia were specifically detected on plastics. Desulfovibrio and Pseudomonas spp. exhibited their highest abundance on steel and Corynebacterium spp. on wood. Scanning electron microscopy (SEM) revealed fissure formation on PET and PE, indicating physical degradation. The presence of free radicals on PET and carbonyl bonds (C=O) on PE, as revealed by Fourier transform infrared (FTIR) spectroscopy, indicated abiotic degradation while hydroxyl groups and spectral peaks for proteins and polysaccharides on PE indicated biotic degradation. We conclude that fouling microbial communities are not only substrate-specific but also location-specific and microbes developing on plastics could potentially contribute to their degradation in the marine environment.