Preparation of long-term cycling stable ni-rich concentration–gradient NCMA cathode materials for li-ion batteries

Nickel-rich (Ni > 90 %) cathodes are regarded as one of the most attractive because of their high energy density, despite their poor stability and cycle life. To improve their performance, in this study we synthesized a double concentration-gradient layered Li[Ni0.90Co0.04Mn0.03Al0.03]O2 oxide (CG-NCMA) using a continuous co-precipitation Taylor–Couette cylindrical reactor (TCCR) with a Ni-rich-core, an Mn-rich surface, and Al on top. The concentration-gradient morphology was confirmed through cross-sectional EDX line scanning. The as-synthesized sample exhibited excellent electrochemical performance at high rates (5C/10C), as well as cyclability (91.5 % after 100 cycles and 70.3 % after 500 cycles at 1C), superior to that (83.4 % and 47.6 %) of its non-concentration-gradient counterpart (UC-NCMA). The Mn-rich surface and presence of Al helped the material stay structurally robust, even after 500 cycles, while also suppressing side reactions between the electrode and electrolyte, resulting in better overall electrochemical performance. These enhancements in performance were studied using TEM, SEM, in-situ-XRD, XPS, CV, EIS and post-mortem analyses. This synthetic method enables the highly scalable production of CG-NCMA samples with two concentration-gradient structures for practical applications in Li-ion batteries

Fascinating bifunctional electrocatalytic activity via a mesoporous structured FeMnO3@ZrO2 matrix as an efficient cathode for Li-O2 batteries

Nonaqueous Li-O2 batteries have remarkable potential for use in future-generation sustainable green energy storage systems. Perovskites of the type ABO3 provide bifunctional electrocatalytic activity superior to that of dual mixed-metal oxides due to the presence of crystallographic defects and oxygen vacancies, arising from the multivalency of the A and B cations. In this study, we used a facile hydrothermal method with an ammonia solution to modify coralline-like ZrO2 with Fe0.5Mn0.5O3 (FeMnO3) and graphene nanosheets (GNSs). The porous structure of the resulting ZrO2@FeMnO3/GNS system featured a high surface area and large volume, thereby exposing a great number of active sites. X-ray photoelectron spectroscopy revealed that the surface of the as-synthesized FeMnO3@ZrO2/GNS cathode material was rich with oxygen vacancies (i.e., a huge quantity of defects). This coralline-like bifunctional electrocatalyst possessed effective redox capability between Li2O2 and O2 as a result of its excellent catalytic activity in the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). We examined the charge/discharge behavior of corresponding electrodes (EL-cell type for Li-O2 battery) in the voltage range of 2.0-4.5 V (vs Li/Li+). The synergistic effects of the high catalytic ability and coralline-like microstructure of our ZrO2@FeMnO3/GNS catalyst for Li-O2 batteries resulted in its superior rate capability and excellent long-term cyclability, sustaining 100 cycles at 100 mA g-1 with a limited capacity of 1000 mAh g-1. The cell overpotential was ∼0.14 V when adding LiI as a redox mediator, resulting in a more practical Li-O2 battery with the ZrO2@FeMnO3/GNS catalyst. Therefore, ZrO2@FeMnO3/GNS catalysts having distinctive coralline-like structures can display outstanding bifunctional catalytic activity and electrical conductivity, suggesting great potential for enhanced Li-O2 battery applications

Anisotropic ultrafast spin/valley dynamics in WTe2 films

WTe2 Weyl semimetal hosts the natural broken inversion symmetry and strong spin orbit coupling, making it promising for exotic spin/valley dynamics within a picosecond timescale. Here, we unveil an anisotropic ultrafast spin/valley dynamics in centimeter-scale, single-crystalline Td-WTe2 films using a femtosecond pump-probe technique at room temperature. We observe a transient (~0.8 ps) intra-valley transition and a subsequent polarization duration (~5 ps) during the whole spin/valley relaxation process. Furthermore, the relaxation exhibits the remarkable anisotropy of approximately six-fold and two-fold symmetries due to the intrinsic anisotropy along the crystalline orientation and the extrinsic matrix element effect, respectively. Our results offer a prospect for the ultrafast manipulation of spin/valleytronics in topological quantum materials for dissipationless high-speed spin/valleytronic devices.Comment: 21 pages, 4 figure

DNA Immunization with Fusion of CTLA-4 to Hepatitis B Virus (HBV) Core Protein Enhanced Th2 Type Responses and Cleared HBV with an Accelerated Kinetic

BACKGROUND: Typically, DNA immunization via the intramuscular route induces specific, Th1-dominant immune responses. However, plasmids expressing viral proteins fused to cytotoxic T lymphocyte antigen 4 (CTLA-4) primed Th2-biased responses and were able to induced effective protection against viral challenge in the woodchuck model. Thus, we addressed the question in the mouse model how the Th1/Th2 bias of primed immune responses by a DNA vaccine influences hepatitis B virus (HBV) clearance. PRINCIPAL FINDINGS: Plasmids expressing HBV core protein (HBcAg) or HBV e antigen and HBcAg fused to the extracellular domain of CTLA-4 (pCTLA-4-HBc), CD27, and full length CD40L were constructed. Immunizations of these DNA plasmids induced HBcAg-specific antibody and cytotoxic T-cell responses in mice, but with different characteristics regarding the titers and subtypes of specific antibodies and intensity of T-cell responses. The plasmid pHBc expressing HBcAg induced an IgG2a-dominant response while immunizations of pCTLA-4-HBc induced a balanced IgG1/IgG2a response. To assess the protective values of the immune responses of different characteristics, mice were pre-immunized with pCTLA-4-HBc and pHBc, and challenged by hydrodynamic injection (HI) of pAAV/HBV1.2. HBV surface antigen (HBsAg) and DNA in peripheral blood and HBcAg in liver tissue were cleared with significantly accelerated kinetics in both groups. The clearance of HBsAg was completed within 16 days in immunized mice while more than 50% of the control mice are still positive for HBsAg on day 22. Stronger HBcAg-specific T-cell responses were primed by pHBc correlating with a more rapid decline of HBcAg expression in liver tissue, while anti-HBs antibody response developed rapidly in the mice immunized with pCTLA-4-HBc, indicating that the Th1/Th2 bias of vaccine-primed immune responses influences the mode of viral clearance. CONCLUSION: Viral clearance could be efficiently achieved by Th1/Th2-balanced immune response, with a small but significant shift in T-cell and B-cell immune responses

Blow-Up and Global Existence for a Quasilinear Parabolic System

The problem of solutions to a class of quasilinear coupling parabolic system was studied. By constructing weak upper-solutions and weak lower-solutions, we obtain the global existence and blow-up of solutions under appropriate conditions

Global Aromaticity in Macrocyclic Polyradicaloids: Hückel’s Rule or Baird’s Rule?

10.1021/acs.accounts.9b00257Accounts of Chemical Research5282309-232

Limosilactobacillus reuteri alleviates weaned stress by improving immune function and gut microbiota in piglets

Weaned stress may damage the tissue development, barrier function, and balance of microbiota of gut, resulting in the diarrhea and reduced growth performance of piglets. Probiotics with excellent characteristics can enhance the resistance of piglets to weaned stress. Under a poor sanitary condition, the Limosilactobacillus reuteri (L. reuteri) SLZX19-12 was supplemented to check its effects for piglets. Results showed that supplementation of L. reuteri significantly decreased the diarrhea incident, improved the growth performance, and enhanced the barrier integrity of gut. In ileum, L. reuteri decreased inflammation by NFκB p65 pathway, increased propionate, TCDCA, and THDCA contents, and regulated microbiota. In colon, L. reuteri decreased the inflammation by NFκB p65 pathway, reduced DCA content, and regulated microbiota. Therefore, the supplementation of L. reuteri may alleviate weaned stress by improving immune function and regulating the gut microbiota in piglets