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• The effect of metal elements Pd, Mg and Ti on tritium release on the Li 2 O (111) surface was studied for the first time. • Metal elements Pd, Mg and Ti can be used as catalysts in the experiment of releasing tritium on the Li 2 O (111) surface. • Compared with the dopants Pd and Mg, Ti can significantly catalyze the release of tritium. In this study, the effect of doped metal atoms Pd, Mg and Ti on the release of tritium on the Li 2 O (111) surface is studied by using density functional theory. On the clean Li 2 O (111) surface, the formation energies of T 2 O and T 2 are 3.41 eV and 6.30 eV, respectively. About the Li 2 O (111) surface doped with Pd, Mg and Ti, the T 2 O molecule are formed spontaneously, and the desorption energies are 1.26, 0.58 and 0.18 eV, respectively. The formation energy of T 2 molecule is 2.83 eV, on the surface of Ti-doped Li 2 O (111). By analyzing Bader charge, charge density difference (CDD), local density of state (LDOS) and the formation energy of oxygen vacancy, we found that dopants can affect the interaction of surrounding atoms through charge transfer and reduce the O vacancy formation energy, and then generate the desorption sites with low activation energy, thereby promoting the formation and desorption of T 2 O or T 2. In a word, doping Pd, Mg and Ti on the Li 2 O (111) surface can catalyze the release of tritium. [ABSTRACT FROM AUTHOR]

The production of polypeptides via the ring-opening polymerization (ROP) of N -carboxyanhydride (NCA) is usually conducted under stringent anhydrous conditions. The ROP of proline NCA (ProNCA) for the synthesis of poly-L-proline (PLP) is particularly challenging due to the premature product precipitation as polyproline type I helices, leading to slow reactions for up to one week, poor control of the molar mass and laborious workup. Here, we report the unexpected water-assisted controlled ROP of ProNCA, which affords well-defined PLP as polyproline II helices in 2–5 minutes and almost-quantitative yields. Experimental and theoretical studies together suggest the as-yet-unreported role of water in facilitating proton shift, which significantly lowers the energy barrier of the chain propagation. The scope of initiators can be expanded from hydrophobic amines to encompass hydrophilic amines and thiol-bearing nucleophiles, including complex biomacromolecules such as proteins. Protein-mediated ROP of ProNCA conveniently affords various protein-PLP conjugates via a grafting-from approach. PLP modification not only preserves the biological activities of the native proteins, but also enhances their resistance to extreme conditions. Moreover, PLP modification extends the elimination half-life of asparaginase (ASNase) 18-fold and mitigates the immunogenicity of wt ASNase >250-fold (ASNase is a first-line anticancer drug for lymphoma treatment). This work provides a simple solution to a long-standing problem in PLP synthesis, and offers valuable guidance for the development of water-resistant ROP of other proline-like NCAs. The facile access to PLP can greatly boost the application potential of PLP-based functional materials for engineering industry enzymes and therapeutic proteins. [ABSTRACT FROM AUTHOR]

CO oxidation has been performed on Co 3 O 4 nanocubes and Co(OH) 2 nanosheets as model catalysts. The reaction rate of CO on Co 3 O 4 /Co(OH) 2 nanocomposites obtained by one-pot synthesis is about ~ two orders of magnitude higher than that on Co 3 O 4 nanomaterials. The catalytic behaviors of different nanomaterials revealed that the assembly with nano building blocks cause the catalytic sites much more active for CO oxidation. The kinetic data showed that the activation energy for CO oxidation over Co 3 O 4 /Co(OH) 2 nanocomposites was lower than that of other nanomaterials. Since Co(OH) 2 nanosheets can prevent Co 3 O 4 nanocubes aggregating, nanocomposites kept good catalytic stability. [ABSTRACT FROM AUTHOR]