► Difficulties in corrosion testing in highly resistive and inhomogeneous media. ► Methods designed for corrosion testing in highly resistive and inhomogeneous media. ► Methods for avoiding IR drop ...problems associated with polarisation measurement.
Corrosion measurement in highly resistive and inhomogeneous media can be very challenging due to practical difficulties in setting up and maintaining testing cells and sensors, problems associated with
IR potential drops and nonuniform polarisation current distribution, and limitations associated with localised corrosion monitoring and detection. Many technological innovations have been made over the past decade to address these issues with reports scattered throughout the literature. This paper provides an overview of innovative experimental methods designed for corrosion testing and monitoring in highly-resistive and inhomogeneous media, with particular focus on localised corrosion measurement using electrode array and electrochemical noise techniques.
► Analysis of the effects of EI and EH on pitting corrosion initiation by revisiting research findings reported in the literature. ► Analysis of pitting initiation mechanisms by revisiting WBE data ...showing spatial and temporal information on pitting corrosion processes. ► Experimental evidences illustrating an alternative mechanism of pitting corrosion initiation.
The effects of electrode inhomogeneity (EI) and electrochemical heterogeneity (EH) on pitting corrosion initiation have been analysed by revisiting research findings reported in the literature and experimental evidences obtained in our laboratories using the wire beam electrode (WBE) method. Two mechanisms of pitting corrosion initiation have been identified on bare metal surfaces exposed directly to electrolytes. For WBE surface under free corrosion or low anodic polarisation conditions the initiation of pitting corrosion was found to be due to the disappearance of minor anodes, leading to accelerated dissolution of a few remaining major anodes. The nucleation stage of pitting corrosion appeared to be controlled by EI, while the propagation stage appeared to be determined by EH. For WBE surface under large anodic polarisation the initiation of pitting corrosion was found to be due to the formation of active new anodic sites, which is in agreement with the conventional mechanism of pitting nucleation.
•A novel approach has been taken to examine the details of erosion–corrosion interactions.•Flow accelerated corrosion propagates due to anolyte transportation and micro-turbulences.•Erosion corrosion ...propagates due to the impingement of anodic corrosion sites by sand.•Evidences showing interactions between electrochemical anodes and mechanical erosion.
The initiation and propagation of flow accelerated corrosion (FAC) and erosion corrosion (EC) have been explored using an electrochemically integrated multi-electrode array and electrochemical impedance spectroscopy. Results show that the propagation of FAC is due to flow generated interfacial anolyte transportation and micro-turbulences around the initial pits, causing the “flow mark” corrosion appearance. While the propagation of EC appears to be mainly due to the impingement of the initial anodic sites by sand particles, inducing the ‘crater-like’ corrosion feature. Mechanical erosion was found to concentrate on electrochemical corrosion anodes, confirming active interactions between erosion and corrosion processes.
► A new experiment method for evaluating under-deposit corrosion and its inhibitors. ► Under-deposit corrosion did not occur in a CO
2 saturated pure brine solution. ► Inhibitor imidazoline addition ...and O
2 contamination initiated under-deposit corrosion. ► Inhibitor imidazoline reduced general corrosion but enhanced localised corrosion.
A new experimental method has been applied to evaluate under-deposit corrosion and its inhibition by means of an electrochemically integrated multi-electrode array, namely the wire beam electrode (WBE). Maps showing galvanic current and corrosion potential distributions were measured from a WBE surface that was partially covered by sand. Under-deposit corrosion did not occur during the exposure of the WBE to carbon dioxide saturated brine under ambient temperature. The introduction of corrosion inhibitor imidazoline and oxygen into the brine was found to significantly affect the patterns and rates of corrosion, leading to the initiation of under-deposit corrosion over the WBE.
A novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was recently identified as the causative agent for the coronavirus disease 2019 (COVID-19) outbreak that has ...generated a global health crisis. We use a combination of genomic analysis and sensitive profile-based sequence and structure analysis to understand the potential pathogenesis determinants of this virus. As a result, we identify several fast-evolving genomic regions that might be at the interface of virus-host interactions, corresponding to the receptor binding domain of the Spike protein, the three tandem Macro fold domains in ORF1a, and the uncharacterized protein ORF8. Further, we show that ORF8 and several other proteins from alpha- and beta-CoVs belong to novel families of immunoglobulin (Ig) proteins. Among them, ORF8 is distinguished by being rapidly evolving, possessing a unique insert, and having a hypervariable position among SARS-CoV-2 genomes in its predicted ligand-binding groove. We also uncover numerous Ig domain proteins from several unrelated metazoan viruses, which are distinct in sequence and structure but share comparable architectures to those of the CoV Ig domain proteins. Hence, we propose that SARS-CoV-2 ORF8 and other previously unidentified CoV Ig domain proteins fall under the umbrella of a widespread strategy of deployment of Ig domain proteins in animal viruses as pathogenicity factors that modulate host immunity. The rapid evolution of the ORF8 Ig domain proteins points to a potential evolutionary arms race between viruses and hosts, likely arising from immune pressure, and suggests a role in transmission between distinct host species.
The ongoing COVID-19 pandemic strongly emphasizes the need for a more complete understanding of the biology and pathogenesis of its causative agent SARS-CoV-2. Despite intense scrutiny, several proteins encoded by the genomes of SARS-CoV-2 and other SARS-like coronaviruses remain enigmatic. Moreover, the high infectivity and severity of SARS-CoV-2 in certain individuals make wet-lab studies currently challenging. In this study, we used a series of computational strategies to identify several fast-evolving regions of SARS-CoV-2 proteins which are potentially under host immune pressure. Most notably, the hitherto-uncharacterized protein encoded by ORF8 is one of them. Using sensitive sequence and structural analysis methods, we show that ORF8 and several other proteins from alpha- and beta-coronavirus comprise novel families of immunoglobulin domain proteins, which might function as potential immune modulators to delay or attenuate the host immune response against the viruses.
The transcription factor FOXM1 binds to its consensus sequence at promoters through its DNA binding domain (DBD) and activates proliferation-associated genes. The aberrant overexpression of FOXM1 ...correlates with tumorigenesis and progression of many cancers. Inhibiting FOXM1 transcriptional activities is proposed as a potential therapeutic strategy for cancer treatment. In this study, we obtained a FOXM1-specific single stranded DNA aptamer (FOXM1 Apt) by SELEX with a recombinant FOXM1 DBD protein as the target of selection. The binding of FOXM1 Apt to FOXM1 proteins were confirmed with electrophoretic mobility shift assays (EMSAs) and fluorescence polarization (FP) assays. Phosphorthioate-modified FOXM1 Apt (M-FOXM1 Apt) bound to FOXM1 as wild type FOXM1 Apt, and co-localized with FOXM1 in nucleus. M-FOXM1-Apt abolished the binding of FOXM1 on its consensus binding sites and suppressed FOXM1 transcriptional activities. Compared with the RNA interference of FOXM1 in cancer cells, M-FOXM1 Apt repressed cell proliferation and the expression of FOXM1 target genes without changing FOXM1 levels. Our results suggest that the obtained FOXM1 Apt could be used as a probe for FOXM1 detection and an inhibitor of FOXM1 transcriptional functions in cancer cells at the same time, providing a potential reagent for cancer diagnosis and treatment in the future.
Small-diameter tissue-engineered vascular grafts are urgently needed for clinic arterial substitute. To simulate the structures and functions of natural blood vessels, we designed a novel ...triple-layer poly(ε-caprolactone) (PCL) fibrous vascular graft by combining E-jet 3D printing and electrospinning techniques. The resultant vascular graft consisted of an interior layer comprising 3D-printed highly aligned strong fibers, a middle layer made by electrospun densely fibers, and an exterior structure composed of mixed fibers fabricated by co-electrospraying. The biocompatible triple-layer graft was used for
in vivo
implantation, and results demonstrated that the longitudinally-aligned fibers within the lumen of the graft could enhance the proliferation and migration of endothelial cells, while maintained good mechanical properties. The exterior layer provided a pathway that encouraged cells to migrate into the scaffold after implantation. This experimental graft overcame the limitations of conventionally electrospun vascular grafts of inadequate porosity and lowly cell penetration. The unique structure of the triple-layer vascular graft promoted cell growth and infiltration
in vivo
, thus provided an encouraging substitute for
in situ
tissue engineering.
Stainless steels like 316 stainless steel (SS316) and 2205 duplex stainless steel (SS2205) have been widely used in industries such as desalination because of their excellent general corrosion ...resistance. However the corrosion resistant characteristics of stainless steels may be adversely affected by welding process that could result in modifications of local composition and microstructures. It is therefore critical to assess and understand the corrosion behaviors of stainless steel weldments. In this work, a novel approach to carry out electrochemical measurements on selected welding zones was employed. Standard polarization tests were applied to the selected zones on stainless steel weldments exposed to sodium chloride solutions. Weldments of SS316 and SS2205 were chosen as examples to illustrate the application of this novel electrochemical measurement approach. The results showed that each zone on the stainless steel weldments exhibited different corrosion characteristics and the weldments of SS316 and SS2205 behaved differently. The results suggested that SS2205 weldment was less resistant to pitting corrosion than SS316 weldment, although SS2205 base metal had much better pitting corrosion resistance than SS316 base metal. The corrosion behavior of each of the zones was confirmed to be affected by the surface morphology, microstructure and surface composition.
•A new method was applied to study the corrosion behaviors of selected welding zones.•Each zone on the stainless steel weldment exhibited different corrosion behaviors.•Corrosion behaviors were discussed from surface conditions and microstructure.•The method could distinguish different corrosion behaviors of different welding zones.
Highlights • This study confirms the role of FOXA2 in preventing EMT and metastasis of breast cancer. • FOXA2 prevents EMT by stimulating E-cadherin transcription and repressing ZEB2 via recruiting ...TLE3 to ZEB2 promoter. • The upregulation of FOXA2 could be a therapeutic approach for metastasis of breast cancer.
The ionome of the rice grain is crucial for the health of populations that consume rice as a staple food. However, the contribution of phenotypic plasticity to the variation of rice grain ionome and ...the genetic architecture of phenotypic plasticity are poorly understood. In this study, we investigated the rice grain ionome of a rice diversity panel in up to eight environments. A considerable proportion of phenotypic variance can be attributed to phenotypic plasticity. Then, phenotypic plasticity and mean phenotype were quantified using Bayesian Finlay-Wilkinson regression, and a significant correlation between them was observed. However, the genetic architecture of mean phenotype was distinct from that of phenotypic plasticity. Also, the correlation between them was mainly attributed to the phenotypic divergence between rice subspecies. Furthermore, the results of whole-genome regression analysis showed that the genetic loci related to phenotypic plasticity can explain a considerable proportion of the phenotypic variance in some environments, especially for Cd, Cu, Mn, and Zn. Our study not only sheds light on the genetic architecture of phenotypic plasticity of the rice grain ionome but also suggests that the genetic loci which related to phenotypic plasticity are valuable in rice grain ionome improvement breeding.
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