An orbital principle to design P2-NaxMO2 cathode materials for sodium-ion batteries.

Layered oxide materials are regarded to be the most promising high-performance cathode materials for sodium-ion batteries owing to their high working voltage and facile synthesis. Here, we study the influences of 3d transition metals on the cohesive energies, structural changes and operating voltages of P2-NaxMO2 during discharge based on first-principles calculations. Our results confirm that the performances of P2-NaxMO2 are associated with the chemical properties of the transition metals. In addition to this, we disclose that the involved orbitals of the 3d transition metal also greatly impact the electrochemical performance of the P2-NaxMO2 material during discharge according to the analysis of electronic structures. The jumps in the working voltage and volume during discharge are closely related to the occupation of the eg and t2g orbitals. Therefore, it is necessary to ensure that the discharge or charge process is carried out in one degenerate orbital to avoid jumps in the voltage and volume of the material. Our results could shed a light on the subsequent design of layered oxide cathodes with high cycle stability and a smooth voltage curve.

Multi-core yolk-shell-structured Bi2Se3@C nanocomposite as an anode for high-performance lithium-ion batteries.

Emerging Bi2Se3-based anode materials are attracting great interest for lithium storage because of their high theoretical capacity. Although quite attractive, Bi2Se3 still faces the problem of large volume expansion during lithiation/delithiation, leading to poor cycling stability. Herein, a multi-core yolk-shell Bi2Se3@C nanocomposite was designed and synthesized via a solvothermal method followed by heat treatment. The as-prepared yolk-shell nanocomposite consists of two parts: several Bi2Se3 nanospheres (diameter of approximately 100 nm) as a core, and carbon (thickness of approximately 16 nm) as the shell. Owing to its unique structural features, multi-core yolk-shell Bi2Se3@C nanocomposite demonstrates excellent cycling stability with a capacity of 392.2 mA h g-1 at 0.2 A g-1 after 100 cycles for lithium-ion batteries (LIBs). A reversible capacity of 416.9 mA h g-1 can be maintained even at a higher current density of 1 A g-1 after 1200 cycles. The reason for the superior electrochemical performance was further explored through electrochemical kinetic analysis and theoretical calculations. This work provides an effective strategy for the preparation of multi-core yolk-shell anode materials, and also affords a new method by which to prepare high-performance LIBs.

Role of Human Mesangial-Tubular Crosstalk in Secretory IgA-Induced IgA Nephropathy.

BACKGROUND: IgA nephropathy (IgAN) is characterized by the mesangial deposition of pathogenic IgA. We previously detected the deposition of pathogenic secretory IgA (SIgA) in the mesangium of about one-third of IgAN patients. Tubulointerstitial injury has an important role in the development of IgAN. However, the relationship between SIgA and tubulointerstitial damage is currently unclear. In this work, the role of the mesangial-tubular crosstalk was explored in the tubulointerstitial damage in SIgA-induced IgAN. METHODS: SIgA deposition in renal tissues of IgAN patients was detected by immunofluorescence. Flow cytometry was used to assess the binding of SIgA to human renal mesangial cells (HRMC) and human proximal tubule epithelial (HK-2) cells. HK-2 was co-cultured with HRMC added with SIgA isolated from patients or normal volunteers. Protein synthesis and gene expressions of TNF-α, TGF-ß1, and MCP-1 were determined by ELISA and PCR, respectively. The expressions of the above cytokines in renal tissues of patients and normal controls were detected by immunohistochemistry. RESULTS: Twenty-nine of 96 patients had SIgA deposition in the mesangium, but SIgA was rarely detected in the tubulointerstitium. The binding rate of SIgA to HK-2 (2.79%) was significantly lower than that of HRMC (81.6%) (p < 0.001). The expressions of TNF-α, TGF-ß1, and MCP-1 in HRMC were significantly higher than in SIgA-stimulated HK-2 (p < 0.05), and their expressions were significantly higher in the SIgA-stimulated co-culture group compared with SIgA-stimulated HRMC (p < 0.05). The expressions of the above cytokines were mainly detected in tubulointerstitium of IgAN patients with positive and negative SIgA deposition, without significant difference between the 2 groups, but to a significantly higher level than that in normal controls, and their expressions positively correlated with tubulointerstitial injury. CONCLUSION: Inflammatory factors released from the mesangium after SIgA deposition might mediate tubulointerstitial damage via mesangial-tubular crosstalk in IgAN.

Topological semimetal state with triply degenerate nodal points in a stable Cu2Te structure.

Cu2Te is commonly used as the backside contact of CdTe-based solar cells. We predict a stable topological semimetal structure of Cu2Te(R3m) with triply degenerate nodal points near the Fermi energy. Triply degenerate nodal points are formed by the band crossing between two states with angular momentum j equal to 3/2 and 1/2 along the unique C3 axis. The anisotropic strain breaking C3 symmetry opens the energy gap, and transforms semimetal Cu2Te(R3m) into a topological insulator. It provides strong evidence for understanding the unconventional large linear magnetoresistance in Cu2-xTe. The band crossing of Cu2Te(R3m) strongly depends on the orbital on-site energy difference and the SOC strength. Crystal structures with the space group R3m (no. 160) are a good platform to obtain topological semimetals with triply degenerate nodal points. Compounds X2Y (X = Cu, Ag, Au, Y = O, S, Se, Te) except for Au2S and Cu2O are topological semimetals with triply degenerate nodal points around the Fermi energy.

The TLR4-MyD88-NF-κB pathway is involved in sIgA-mediated IgA nephropathy.

Previous studies have shown that secretory IgA (sIgA) was critically involved in IgA nephropathy (IgAN) immune responses. Toll-like receptors (TLRs), especially TLR4 which participates in mucosal immunity, may be involved in the pathogenesis of IgAN. The purpose of this study was to investigate whether sIgA and TLR4 interact to mediate kidney damage in IgAN patients. IgAN patients with positive sIgA deposition in renal tissues were screened by immunofluorescence assay. Patient salivary sIgA (P-sIgA) was collected and purified by jacalin affinity chromatography. Salivary sIgA from healthy volunteers was used as a control (N-sIgA). Expression of TLR4, MyD88, NF-κB, TNF-α, IL-6, and MCP-1 were detected in the mesangial area of IgAN patients by immunohistochemistry, the expression levels in patients with positive sIgA deposition were higher than that with negative sIgA deposition. Human renal mesangial cells (HRMCs) were cultured in vitro, flow cytometry showed that P-sIgA bound HRMCs significantly better than N-sIgA. HRMCs were cultured in the presence of sIgA (400 µg/mL) for 24 h, compared with cells cultured with N-sIgA, HRMCs cultured in vitro with P-sIgA showed enhanced expression of TLR4, increased secretion of TNF-α, IL-6, and MCP-1, and increased expression of MyD88/NF-κB. TLR4 shRNA silencing and NF-κB inhibition both reduced the ability of HRMCs to synthesize TNF-α, IL-6, and MCP-1. Our results indicate that sIgA may induce high expression of TLR4 in HRMCs and further activate downstream signalling pathways, prompting HRMCs to secrete multiple cytokines and thereby mediating kidney damage in IgAN patients.

Diphenyl polysulfides: cathodes with excellent lithiation performance and high specific energy for LSBs.

Reversible lithium-sulfur batteries (LSBs) are considered one of the most promising next-generation energy storage systems. However, the shuttling effect of lithium polysulfide significantly weakens the electrochemical properties and the cycle life, hindering its practical application. Organo-sulfides are unique materials with low cost, profuse content and high capacity. Here, via quantum chemical calculations, we introduce a class of diphenyl polysulfides, PhS n Ph (2 ≤ n ≤ 15), which are all structurally stable, confirmed by calculation of their Gibbs free energies. The theoretical specific energy of PhS15Ph is high, up to 2632 W h kg-1, exceeding that of S8. By calculating the bond dissociation energy of S-S in PhS n Ph molecules, we analyze the breaking processes of the S-S bonds in each step of lithiation. The microscopic mechanism of the fast reaction kinetics of PhS n Ph cathodes is explored. It is phenyl that prevents the formation of soluble long-chain polysulfide molecules (Li2S4, Li2S6, Li2S8) in the lithiation process, efficiently weakening the "shuttle effect".