Rearranged Copolyurea Networks for Selective Carbon Dioxide Adsorption at Room Temperature

Copolyurea networks (co-UNs) were synthesized via crosslinking polymerization of a mixture of tetrakis(4-aminophenyl)methane (TAPM) and melamine with hexamethylene diisocyanate (HDI) using the organic sol-gel polymerization method. The subsequent thermal treatment of between 200 and 400 °C induced the sintering of the powdery polyurea networks to form porous frameworks via urea bond rearrangement and the removal of volatile hexamethylene moieties. Incorporating melamine into the networks resulted in a higher nitrogen content and micropore ratio, whereas the overall porosity decreased with the melamine composition. The rearranged network composed of the tetraamine/melamine units in an 80:20 ratio showed the highest carbon dioxide adsorption quantity at room temperature. The results show that optimizing the chemical structure and porosity of polyurea-based networks can lead to carbon dioxide adsorbents working at elevated temperatures.

Shear induced deformation twinning evolution in thermoelectric InSb

Twin boundary (TB) engineering has been widely applied to enhance the strength and plasticity of metals and alloys, but is rarely adopted in thermoelectric (TE) semiconductors. Our previous first-principles results showed that nanotwins can strengthen TE Indium Antimony (InSb) through In–Sb covalent bond rearrangement at the TBs. Herein, we further show that shear-induced deformation twinning enhances plasticity of InSb. We demonstrate this by employing large-scale molecular dynamics (MD) to follow the shear stress response of flawless single-crystal InSb along various slip systems. We observed that the maximum shear strain for the $$(111)[11\bar 2]$$ ( 111 ) [ 11 2 ¯ ] slip system can be up to 0.85 due to shear-induced deformation twinning. We attribute this deformation twinning to the “catching bond” involving breaking and re-formation of In–Sb bond in InSb. This finding opens up a strategy to increase the plasticity of TE InSb by deformation twinning, which is expected to be implemented in other isotypic III–V semiconductors with zinc blende structure.

Preparation of 2-phospholene oxides by the isomerization of 3-phospholene oxides

A series of 1-substituted-3-methyl-2-phospholene oxides was prepared from the corresponding 3-phospholene oxides by double bond rearrangement. The 2-phospholene oxides could be obtained by heating the 3-phospholene oxides in methanesulfonic acid, or via the formation of cyclic chlorophosphonium salts. Whereas mixtures of the 2- and 3-phospholene oxides formed, when the isomerization of 3-phospholene oxides was attempted under thermal conditions, or in the presence of a base. The mechanisms of the various double bond migration pathways were elucidated by quantum chemical calculations.

The redox-coupled proton-channel opening in cytochrome c oxidase

The interplay of cytochrome c oxidase's cofactor electrostatics, long-range conformational changes, H-bond rearrangement, and water dynamics enables transient proton-channel activation.

Pathological consequences of the unfolded protein response and downstream protein disulphide isomerases in pulmonary viral infection and disease

Protein folding within the endoplasmic reticulum (ER) exists in a delicate balance; perturbations of this balance can overload the folding capacity of the ER and disruptions of ER homoeostasis is implicated in numerous diseases. The unfolded protein response (UPR), a complex adaptive stress response, attempts to restore normal proteostasis, in part, through the up-regulation of various foldases and chaperone proteins including redox-active protein disulphide isomerases (PDIs). There are currently over 20 members of the PDI family each consisting of varying numbers of thioredoxin-like domains which, generally, assist in oxidative folding and disulphide bond rearrangement of peptides. While there is a large amount of redundancy in client proteins of the various PDIs, the size of the family would indicate more nuanced roles for the individual PDIs. However, the role of individual PDIs in disease pathogenesis remains uncertain. The following review briefly discusses recent findings of ER stress, the UPR and the role of individual PDIs in various respiratory disease states.