Corrosion inhibition and adsorption properties of cerium-amino acid complexes on mild steel in acidic media: Experimental and DFT studies

Abstract

The corrosion inhibition and adsorption behavior of glutamic acid (Glu), glutamine (Gln), and their cerium complexes: cerium glutamate (Ce(Glu)) and cerium glutamine (Ce(Gln)) on mild steel in 0.5?M HCl solutions were studied at 25 and 55?°C and concentration range of 25–200?ppm using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopic (EIS) techniques. The inhibition efficiency was found to be dependent on the concentration and temperature of the system. The potentiodynamic polarization results suggest that the compounds act as mixed-type inhibitors with dominant cathodic inhibition. The mechanism of adsorption deduced from the variation of inhibition efficiency with temperature, as well as the activation parameters, suggest significant physisorption of the inhibitor molecules on the metal surface. The experimental data adhere to the Langmuir and El-Awady et al. kinetic adsorption models. The extent of inhibition was found to be Ce-Gln?>?Gln and Ce-Glu?>?Glu. The scanning electron microscope was employed for the morphological studies and the characteristic of the protective layer on the steel surface verified using UV-Vis spectroscopy and FTIR spectroscopy. Adsorption of the inhibitors on Fe (110) surface was evaluated theoretically.     

快干羟基丙烯酸酯乳液的合成及性能研究

采用核壳乳液聚合方法制备了羟值为 1.5%的低羟丙烯酸酯乳液。研究了聚合物理论 T_g、壳中羟基质量分数、核聚合物 Hansch参数对双组分漆膜干燥速度的影响。结果表明：漆膜干燥速度随理论 T_g、壳中羟基质量分数及核聚合物 Hansch参数的增加而加快，当 T_g为 50 ℃、壳中羟基质量分数为 1.1%、核聚合物 Hansch参数为 3.43时，漆膜于 25 ℃、60%相对湿度下的实干时间可缩短至 95 min，在大巴、工程机械涂装等需要快干的领域具备潜在应用价值。     

Discovery and characterization of tyrosinases from sea anemone pedal disc

Abstract

The formation of underwater adhesion is a complicated physiological process and many different types of enzymes are found to be essential apart from structural proteins. Previous studies have shown that various tyrosinases were present in marine adhesives, but little information is available about the over-expression and enzymatic characterization of these enzymes. Specifically, this study first identified four significantly up-regulated tyrosinases in the pedal disc of Haliplanella luciae by means of multi-omics technology, and made preliminary bioinformatics predictions. Sequence alignment showed that the Tyr1_Hl contained six conserved His residues that bind to copper ions, of which a tyrosinase with diphenolase activity named as Tyr1_Hl^Δ, was expressed in Escherichia coli BL21 (DE3) cells and purified by affinity chromatography. Enzymatic characterization showed that the activity of Tyr1_Hl^Δ was Cu²⁺ dependent and maximum catalytic activities were in 20?mM Tris–HCl (pH 8.0) at 37?°C. In summary, we identified novel tyrosinases in the pedal disks of sea anemone for the first time and the Tyr1_Hl^Δ was successfully recombinant expressed. Our study will provide basis for future exploration of bio-adhesion mechanism and design of bio-adhesives derived from sea anemones.     

A Survey of Underwater Multi-Robot Systems

As a cross-cutting field between ocean development and multi-robot system (MRS), the underwater multi-robot system (UMRS) has gained increasing attention from researchers and engineers in recent decades. In this paper, we present a comprehensive survey of cooperation issues, one of the key components of UMRS, from the perspective of the emergence of new functions. More specifically, we categorize the cooperation in terms of task-space, motion-space, measurement-space, as well as their combination. Further, we analyze the architecture of UMRS from three aspects, i.e., the performance of the individual underwater robot, the new functions of underwater robots, and the technical approaches of MRS. To conclude, we have discussed related promising directions for future research. This survey provides valuable insight into the reasonable utilization of UMRS to attain diverse underwater tasks in complex ocean application scenarios.      

Exploration and design of knitted composites for architectural application: The MeiTing project

Knitted composites are textile composite materials that consist of knitted textile reinforcement and polymer matrix. Knitted composites exhibit great design flexibility by allowing the customization of shapes, textures, and material properties. These features facilitate the optimization of buildings’ material systems and the creation of buildings with light weight and high material efficiency.To achieve such a lightweight, material-efficient building structure with knitted composites, this research investigates the material properties of knitted composites and proposes a design process for building-scale knitted composite systems. In the material study, this research examines certain mechanical properties of the material and the effects of additional design elements. In the design exploration, this research explores the design workflow of the structural form, element arrangement, and knit distribution of the material system at the macro-, meso-, and microscales. The project of MeiTing serves as proof of the concept and the design workflow.     

Interfacial Oxides Evolution of High-Speed Steel Joints by Hot-Compression Bonding

The interfacial oxidation behavior of Cr4Mo4V high-speed steel (HSS) joints undergoing hot-compression bonding was investigated by using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In the heating and holding processes, dispersed rod-like and granular $\delta - {\text{Al}}_{{2}} {\text{O}}_{{3}}$ oxides were formed at the interface and in the matrix near the interface due to the selective oxidation and internal oxidation of Al, while irregular Si–Al–O compounds and spheroidal SiO₂ particles were formed at the interface. After the post-holding treatment, SiO₂ oxides and Si–Al–O compounds were dissolved into the matrix, and $\delta - {\text{Al}}_{{2}} {\text{O}}_{{3}}$ oxides were transformed into nanoscale $\alpha - {\text{Al}}_{{2}} {\text{O}}_{{3}}$ particles, which did not deteriorate the mechanical properties of the joints. The formation and migration of newly-formed grain boundaries by plastic deformation and post-holding treatment were the main mechanism for interface healing. The tensile test results showed that the strength of the healed joints was comparable to that of the base material, and the in-situ tensile observations proved that the fracture was initiated at the grain boundary of the matrix rather than at the interface. The clarification of interfacial oxides and microstructure is essential for the application of hot-compression bonding of HSSs.     

Analysis of Failure of Grinding Balls During Service

Metal Science and Heat Treatment - Causes of failure of grinding balls with diameter 110 mm produced traditionally by forging, quenching and low-temperature tempering are considered. The chemical...     

Susceptibility of chloride ion concentration,temperature, and surface roughness on pitting corrosion of CoCrFeNi medium-entropy alloy

The influence and susceptibility of chloride ion concentration, temperature, and surface roughness on corrosion behavior of single-phase CoCrFeNi medium-entropy alloy (MEA) was examined in NaCl solution. Potentiodynamic polarization results revealed that the corrosion performance of the sample deteriorated with an increase of the chloride ion concentration, temperature, and surface roughness. The pitting potential decreased drastically for samples with higher surface roughness. According to electrochemical impedance spectroscopy, the charge transfer resistance decreased when chloride ion concentration, temperature, and surface roughness increased. Scanning electron micrographs also indicated an increased extent of corrosion damage, especially for the sample with higher surface roughness. It is found that the corrosion resistance is closely related to the wettability of samples, and the surface with the highest roughness shows higher hydrophilicity. The combined results suggested that the pitting damage is more sensitive to surface roughness. Our findings provide a further understanding of the corrosion mechanism of MEAs and guide their applications as structural materials.