ABSTRACT
A facile Mn surface doping process is proposed to improve the thermal and structural stabilities of Ni-rich layered cathode materials (Ni ≥ 80%) for lithium-ion batteries in electric vehicles. Herein, we demonstrate that the surface structure of the Ni-rich layered cathode materials can be stabilized by the introduction of a thin Mn-rich surface layer. This layer effectively reduces the direct exposure of the highly reactive Ni on the surface of the cathode materials, thus enhancing thermal stability and mitigating side reactions associated with highly reactive Ni that causes the loss of reversible capacity. In practice, the Mn surface-doped Ni-rich layered cathode material exhibits a high specific capacity with an improved cycling stability even at a high temperature (60 °C). We believe that our simple approach offers more opportunities to upscale production without any extra caution.
ABSTRACT
Proteasome is a large multisubunit complex involved in intracellular proteolysis in antigen processing for loading MHC class I molecules. Two activators PA28-alpha and PA28-beta, which are induced by interferon-gamma (IFN-gamma), activate this latent enzyme complex. Genes encoding these activators, PSME1 and PSME2, respectively, have been characterized from various mammalian but only from zebrafish among piscine. We have cloned a PSME2 gene homologue from a leukocyte cDNA library of flounder, a marine fish. The flounder PSME2 gene (fPSME2) encompasses 1063 nucleotides and encodes a polypeptide of 242 amino acids (aa), with a deduced molecular weight of 27.2 kDa. The deduced protein has 82% sequence similarity to that of zebrafish and 73-74% sequence similarity to that of various mammalians and shows higher level sequence homology in the C-terminal region. There was a PA28-beta protein subunit-specific insert located at the corresponding to the KEKE motif of PA28-alpha protein. A phylogenetic tree derived using deduced amino acid sequences showed a diversion of piscine PSME2 from mammalian counterpart after diversion of PSME1 and PSME2 from a common ancestral gene. Northern blot analysis revealed a higher level expression of fPSME2 gene in kidney, spleen and muscle tissues of bacterial lipopolysaccharide (LPS) stimulated flounder than those from non-induced flounder.
