Tailoring Coral-Like Fe7Se8@C for Superior Low-Temperature Li/Na-Ion Half/Full Batteries: Synthesis, Structure, and DFT Studies.

The intrinsic charge-transfer property bears the primary responsibility for the sluggish redox kinetics of the common electrode materials, especially operated at low temperatures. Herein, we report the crafting of homogeneously confined Fe7Se8 nanoparticles with a well-defined graphitic carbon matrix that demonstrate a highly efficient charge-transfer system in a designed natural coral-like structure (cl-Fe7Se8@C). Notably, the intricate architecture as well as highly conductive peculiarity of C concurrently satisfy the demands of achieving fast ionic/electrical conductivities for both Li/Na-ion batteries in a wide temperature range. For example, when cl-Fe7Se8@C is employed as the anode material to assemble full batteries with the cathode of Na3V2(PO4)2O2F (NVPOF), decent capacities of 323.1 and 175.9 mA h g-1 can be acquired at temperatures of 25 and -25 °C, respectively. This work is significant for further developing potential anode materials for advanced energy storage and conversion under low-temperature conditions.

Targeted Construction of Amorphous MoSx with an Inherent Chain Molecular Structure for Improved Pseudocapacitive Lithium-Ion Response.

Owing to low ion/electron conductivity and large volume change, transitional metal dichalcogenides (TMDs) suffer from inferior cycle stability and rate capability when used as the anode of lithium-ion batteries (LIBs). To overcome these disadvantages, amorphous molybdenum sulfide (MoSx ) nanospheres were prepared and coated with an ultrathin carbon layer through a simple one-pot reaction. Combining X-ray photoelectron spectroscopy (XPS) with theoretical calculations, MoSx was confirmed as having a special chain molecular structure with two forms of S bonding (S2- and S2 2- ), the optimal adsorption sites of Li+ were located at S2 2- . As a result, the MoSx electrode exhibits superior cycle and rate capacities compared with crystalline 2H-MoS2 (e.g., delivering a high capacity of 612.4 mAh g-1 after 500 cycles at 1 A g-1 ). This is mainly attributed to more exposed active S2 2- sites for Li storage, more Li+ transfer pathways for improved ion conductivity, and suppressed electrode structure pulverization of MoSx derived from the inherent chain-like molecular structure. Quantitative charge storage analysis further demonstrates the improved pseudocapacitive contribution of amorphous MoSx induced by fast reaction kinetics. Moreover, the morphology contrast after cycling demonstrates the dispersion of active materials is more uniform for MoSx than 2H-MoS2 , suggesting the MoSx can well accommodate the volume stress of the electrode during discharging. Through regulating the molecular structure, this work provides an effective targeted strategy to overcome the intrinsic issues of TMDs for high-performance LIBs.

Metastable Marcasite-FeS2 as a New Anode Material for Lithium Ion Batteries: CNFs-Improved Lithiation/Delithiation Reversibility and Li-Storage Properties.

Marcasite (m-FeS2) exhibits higher electronic conductivity than that of pyrite (p-FeS2) because of its lower semiconducting gap (0.4 vs 0.7 eV). Meanwhile, as demonstrates stronger Fe-S bonds and less S-S interactions, the m-FeS2 seems to be a better choice for electrode materials compared to p-FeS2. However, the m-FeS2 has been seldom studied due to its sophisticated synthetic methods until now. Herein, a hierarchical m-FeS2 and carbon nanofibers composite (m-FeS2/CNFs) with grape-cluster structure was designed and successfully prepared by a straightforward hydrothermal method. When evaluated as an electrode material for lithium ion batteries, the m-FeS2/CNFs exhibited superior lithium storage properties with a high reversible capacity of 1399.5 mAh g-1 after 100 cycles at 100 mA g-1 and good rate capability of 782.2 mAh g-1 up to 10 A g-1. The Li-storage mechanism for the lithiation/delithiation processes of m-FeS2/CNFs was systematically investigated by ex situ powder X-ray diffraction patterns and scanning electron microscopy. Interestingly, the hierarchical m-FeS2 microspheres assembled by small FeS2 nanoparticles in the m-FeS2/CNFs composite converted into a mimosa with leaves open shape during Li+ insertion process and vice versa. Accordingly, a "CNFs accelerated decrystallization-recrystallization" mechanism was proposed to explain such morphology variations and the decent electrochemical performance of m-FeS2/CNFs.

[Cloning and expression analysis of transcription factor gene DoWRKY1 in Dendrobium officinale].

WRKY transcription factors are novel transcriptional regulatory factors, which play an important role in regulating plant development, metabolism and other physiological processes. In this study, a new Dendrobium officinale WRKY transcription factor, designated as DoWRKY1 was cloned by using RT-PCR and RACE (GenBank Accession No. KF953910). Bioinformatic analysis demonstrated that, the full-length cDNA of DoWRKY1 was 1,704 bp. And DoWRKY1 contained a 1,629 bp open reading frame (ORF) that encoding a peptide of 542 amino acid residues. The putative DoWRKY1 protein contained two conserved WRKY domains and it belonged to the group I WRKY family protein. Yeast one-hybrid experiment showed that DoWRKY1 had transcriptional activation ability in yeast, and it could activate the expression of downstream report genes (His3 and Ade2). Semi-quantitative RT-PCR experiment showed that DoWRKY1 expressed in roots, stems, leaves and protocorm-like bodies. Real-time qRT-PCR proved that DoWRKY1 could be induced by methyl jasmonate (MeJA) and chitosan (Chitosan), and the expression level of this gene can reach the expression peak at 2 h and 1 h, respectively. These results are useful for further determination of the regulation function of this gene in secondary metabolism of D. officinale.

[Studies on genetic diversity of medicinal Dendrobium by SRAP].

OBJECTIVE: To study the genetic diversity of medicinal Dendrobium by SRAP. METHOD: The genetic diversity of 9 spices Dendrobium was studied by using the optimized SRAP reaction system. The NTSYS software was used to analyze the markers. RESULT: Forty primer pairs were selected from 88 amplified 1 782 polymorphic bands with an average of 44.55 polymorphic bands per primer pair. Cluster analysis using UPGMA method based on the data of SRAP amplified bands by 40 primer pairs showed that 9 spices of could be distinguished into two main groups. Jaccard's similarity coefficient ranged from 0.330 2-0.789 2. CONCLUSION: The results of this research indicate that SRAP molecular marker is efficient to study the medical Dendrobium genetic diversity.