Damage evolution in polymer due to exposure to high-pressure hydrogen gas

The use of hydrogen as a fuel is increasing exponentially, and the most economical way to store and transport hydrogen for fuel use is as a high-pressure gas. Polymers are widely used for hydrogen distribution and storage systems because they are chemically inert towards hydrogen. However, when exposed to high-pressure hydrogen, some hydrogen diffuses through polymers and occupies the preexisting cavities inside the material. Upon depressurization, the hydrogen trapped inside polymer cavities can cause blistering or cracking by expanding these cavities. A continuum mechanics–based deformation model was deployed to predict the stress distribution and damage propagation while the polymer undergoes depressurization after high-pressure hydrogen exposure. The effects of cavity size, cavity location, and pressure inside the cavity on damage initiation and evolution inside the polymer were studied. The stress and damage evolution in the presence of multiple cavities was also studied, because interaction among cavities alters the damage and stress field. It was found that all these factors significantly change the stress state in the polymer, resulting in different paths for damage propagation. The effect of adding carbon black filler particles and plasticizer on the damage was also studied. It was found that damage tolerance of the polymer increases drastically with the addition of carbon black fillers, but decreases with the addition of the plasticizer.     

Structural Cues for Understanding eEF1A2 Moonlighting

Spontaneous mutations in the EEF1A2 gene cause epilepsy and severe neurological disabilities in children. The crystal structure of eEF1A2 protein purified from rabbit skeletal muscle reveals a post-translationally modified dimer that provides information about the sites of interaction with numerous binding partners, including itself, and maps these mutations onto the dimer and tetramer interfaces. The spatial locations of the side chain carboxylates of Glu301 and Glu374, to which phosphatidylethanolamine is uniquely attached via an amide bond, define the anchoring points of eEF1A2 to cellular membranes and interorganellar membrane contact sites. Additional bioinformatic and molecular modeling results provide novel structural insight into the demonstrated binding of eEF1A2 to SH3 domains, the common MAPK docking groove, filamentous actin, and phosphatidylinositol-4 kinase IIIβ. In this new light, the role of eEF1A2 as an ancient, multifaceted, and articulated G protein at the crossroads of autophagy, oncogenesis and viral replication appears very distant from the “canonical” one of delivering aminoacyl-tRNAs to the ribosome that has dominated the scene and much of the thinking for many decades.     

Design of a Cost‐Reduced Flexible Plant for Supercritical Fluid‐Assisted Applications

A novel batch plant for supercritical CO₂ applications is proposed which is not equipped with expensive components, such as high‐pressure pumps, making it particularly suitable for bench‐scale use. For the first time, the use of a hanging scale is suggested to weigh the amount of CO₂ required for the experiment and the use of the thermodynamics to reach the working conditions. The rig is able to cover different applications, e.g., aerogel drying, impregnation, and extraction, showing high flexibility. An approximate cost analysis has been performed considering as a reference a 150‐mL vessel. It has been calculated that both the setup and running costs are considerably lower than the common batch and semicontinuous rigs.     

Developing electrochemical measurements in order to assess anti-corrosive coatings more effectively

The aim of this project was to check reproducibility of results obtained using NOCS (no connection to the substrate) arrangement of the electrochemical noise method (ENM). NOCS involves taking measurements from three nominally identical areas on the coated surface. Thus, no electrical connection to substrate is required. In practice the areas are not identical and various arrangements for connection of the three cells were tried to see if the individual areas could be separated out and whether the individual resistances could be computed. Also different ways of calculating the R_n (noise resistance) and R_sn (spectral noise resistance) parameters were attempted to see which one gave the best comparison with the more standard EIS measurements. The maximum entropy method was recognized to be the most useful for comparison with EIS, as well as for graphic evaluation of results. Regarding distinguishing three areas using different connection arrangements, it was possible to identify the situation when one of the three values was different to the other two. However further experiments are needed before it will be possible to confidently assign an R_n value to each individual area.     

Morphology,structure, and chemistry of nanoclusters in a mechanically alloyed nanostructured ferritic steel

Nanostructured ferritic steels have excellent elevated temperature strengths, creep resistances, and radiation tolerances due to the presence of a high density of Ti–Y–O-enriched nanoclusters. The compositions, morphologies, and structures of the smallest of these nanoclusters with maximum dimensions of ~2–4 nm were investigated in alloy 14YWT by high-resolution scanning transmission electron microscopy and atom probe tomography. Nanoclusters are found to be coherent with truncated rhombic dodecahedron morphologies defined by the {100} and {110} planes in the Fe matrix. Particles have compositions rich in Ti, O, Y, and Cr that are inconsistent with known oxide structures. The smallest nanoclusters appear to lack an identifiable crystal structure. Both nano-diffraction and focal series imaging through the sample thickness suggest that they are amorphous.     

Eurocorr 2013: ‘For a Blue Sky’ - part 3

The 2013 Eurocorr meeting was held at the Estoril Congress Centre in Estoril, near Lisbon, Portugal from 1–5^th September 2013. The focus of the meeting was ‘For a Blue Sky’. The meeting attracted over 870 delegates from 60 countries and over 300 papers and 200 posters were presented during the 27 sessions and 6 workshops. Parts 1–4 of this report will review the technical sessions over four issues with sessions on corrosion of steel in concrete, corrosion in oil and gas production, corrosion in the refinery industry, corrosion in carbon capture and storage applications, corrosion reliability of electronics devices covered in this part.