From cubane-assembled Mn-oxo clusters to monodispersed manganese oxide colloidal nanocrystals.

The assemblies of [M4O4] (M = metal) cubanes represent a fascinating class of materials for a variety of application fields. Although such a structural characteristic is relatively common in small molecules and in extended bulk solids, high nuclearity clusters composed of multiple [M4O4] units as their backbones are rare. In this work, we report two new Mn-oxo clusters, MnII 8MnIII 10O10(OOCMe)12(OMe)14(py)2 ([Mn18-Ac]) and MnII 4MnIII 14O14(OOCCMe3)8(OMe)14(MeOH)5(py) ([Mn18-Piv]), whose core structures are assemblies of either 6- or 7-cubanes in different packing patterns, which have been unambiguously revealed by single crystal X-ray diffraction technique. The cubane-assembled structural features can be deemed as the embryonic structures of the bulk manganese oxide. Herein, this report demonstrates the first case study of utilizing Mn-oxo clusters as precursors for the preparation of manganese oxide nanocrystals, which has never been explored before. Through a simple colloidal synthetic approach, high-quality, monodisperse Mn3O4 nanocrystals can be readily prepared by employing both precursors, while their morphologies were found to be quite different. This work confirms that the structural similarity between precursors and nanomaterials is instrumental in affording more kinetically efficient pathways for materials formation, and the structure of the precursor has a significant impact on the morphology of final nanocrystal products.

Nanotubular Fe2O3 and Mn3O4 with hierarchical porosity as high-performance anode materials for lithium-ion batteries.

Developing eco-friendly and low-cost advanced anode materials, such as Fe2O3 and Mn3O4, is fundamental to improve the electrochemical performance of lithium-ion batteries (LIBs). The rational engineering of the microstructure of Fe2O3 and Mn3O4 to endow it with one-dimensionally and hierarchically porous architecture is a feasible way to further improve and optimize the electrochemical performance of the anode materials. Herein, we demonstrate a facile strategy to prepare nanotubular Fe2O3 and Mn3O4 as advanced anode materials for high-performance LIBs. By combining the merits of the one-dimensionally nanotubular morphology and hierarchically porous structure, limitations in the lithiation activity of Mn3O4 and Fe2O3 anode materials, such as low electrical conductivity, large volume expansion, and sluggish lithium-ion diffusion within the materials, have been effectively overcome. When used as anode materials, t-Fe2O3 and t-Mn3O4 exhibited outstanding electrochemical performances, including a high reversible discharge capacity (859.7 and 901.4 mA h g-1 for t-Fe2O3 and t-Mn3O4, respectively), excellent rate performance, and ultra-stable cycling stability. Such superior electrochemical performances proved the exceptional potential of the materials for the real-world application in LIBs.

[In silico cloning of Efp-0, a novel earthworm fibrinolytic enzyme gene and verification of its coding region by RT-PCR].

There are four different types of N-terminal amino acid sequences (F-I-0, F-I, F-II, F-III) in the multicomponents of earthworm fibrinolytic enzymes (EFE). In GenBank 21 nucleic acid sequences of EFE have been reported. Among them, most of the N-terminal amino acid sequences belong to the F-III type,few belong to the F-II type. Only one is similar to the F-I type, but none to F-I-0. In this research we hoped to obtain the gene encoding component F-I-0 of EFE by the bioinformatics tools. Based on the N-terminal amino acid sequence VVGGSDTTIGQYPHQL of the F-I-0 type from Lumbricus rubellus, a nucleic acid sequence was obtained by in silico cloning from dbEST of Lumbricidae using the software DNAMAN. A new gene of EFE from Eisenia foetida was successfully obtained by RT-PCR using specific primers designed according to this sequence. The new gene named EfP-0 was cloned in pMAL-c2x and expressed as the fusion protein MBP-EfP-0 in the supernatant of lysate. The fusion protein MBP-EfP-0 purified by affinity chromatography had hydrolytic activity on casein plate. Sequencing result shows, EfP-0 has 678bp and encodes a protein of 225 amino acids. The protein is a serine protease belonging to trypsin family. It has similar amino acid composition to F-I-0. BLAST in GenBank shows that the similarity is lower than 40% between EJP-0 gene and other EFE genes. By this we conclude that EfP-0 gene of EFE is a novel gene and it is the first time to be reported, its accession number for Genbank is DQ836917.