The Majorana fermion, which is its own antiparticle and obeys non-Abelian statistics, plays a critical role in topological quantum computing. It can be realized as a bound state at zero energy, ...called a Majorana zero mode (MZM), in the vortex core of a topological superconductor, or at the ends of a nanowire when both superconductivity and strong spin orbital coupling are present. A MZM can be detected as a zero-bias conductance peak (ZBCP) in tunneling spectroscopy. However, in practice, clean and robust MZMs have not been realized in the vortices of a superconductor because of contamination from impurity states or other closely packed Caroli–de Gennes-Matricon (CdGM) states, which hampers further manipulations of MZMs. Here, using scanning tunneling spectroscopy, we show that a ZBCP well separated from the other discrete CdGM states exists ubiquitously in the cores of free vortices in the defect-free regions of(Li0.84Fe0.16)OHFeSe, which has a superconducting transition temperature of 42 K. Moreover, a Dirac-cone-type surface state is observed by angle-resolved photoemission spectroscopy, and its topological nature is confirmed by band calculations. The observed ZBCP can naturally be attributed to a MZM arising from the chiral topological surface state of a bulk superconductor. Thus,(Li0.84Fe0.16)OHFeSeprovides an ideal platform for studying MZMs and topological quantum computing.
Although personal thermal management (PTM) materials for daily routine environments are widely investigated, the exploration of multifunctional PTM materials with excellent feasibility in complex and ...outdoor scenarios is still in its infancy. Herein, inspired by the temperature regulation effect of the atmosphere, a novel design for fabricating solar‐thermal gradient reduced graphene oxide (RGO) aerogel‐based bilayer phase change composite (GRGC) featuring “energy regulation” and “energy inverse compensation” is proposed for self‐adaptive PTM applications. By integrating the solar‐thermal energy conversion ability of RGO, the heat regulation of the aerogel/octadecane bilayer structure with the unique gradient RGO framework inside, and the latent‐heat compensation of octadecane, the bilayer GRGC can serve as an efficient PTM device to mitigate drastic temperature changes of human skin in harsh environments. This multifunctional PTM device can not only keep a warm skin surface microclimate in a frigid environment of −5 °C via the synergistic effect of the solar‐thermal conversion, the aerogel thermal insulation, and the phase‐change latent heat release, but also provide efficient thermal buffering to prevent hyperthermia in hot environments through its phase‐change behavior and its thermal insulation. This gradient and bilayer design opens a new avenue for fabricating self‐adaptive PTM devices for applications in harsh environments.
Gradient RGO aerogel‐based bilayer phase change composite featuring “energy regulation” and “energy inverse compensation” is designed for self‐adaptive personal thermal management. Thanks to the synergy of efficient solar‐thermal energy conversion, afferent heat regulation, and latent‐heat compensation, the bilayer phase change composite can alleviate acute temperature changes and maintain moderate body microenvironments in harsh scenarios, delivering extraordinary personal thermal management performances.
Thielavin A (1) is a fungal depside composed of one 3‐methylorsellinic acid and two 3,5‐dimethylorsellinic acid units. It displays diverse biological activities. However, the mechanism underlying the ...assembly of the heterotrimeric structure of 1 remains to be clarified. In this study, we identified the polyketide synthase (PKS) involved in the biosynthesis of 1. This PKS, designated as ThiA, possesses an unusual domain organization with the C‐methyltransferase (MT) domain situated at the C‐terminus following the thioesterase (TE) domain. Our findings indicated that the TE domain is solely responsible for two rounds of ester bond formation, along with subsequent chain hydrolysis. We identified a plausible mechanism for TE‐catalyzed reactions and obtained insights into how a single PKS can selectively yield a specific heterotrimeric product. In particular, the tandem acyl carrier protein domains of ThiA are critical for programmed methylation by the MT domain. Overall, this study highlighted the occurrence of highly optimized domain–domain communication within ThiA for the selective synthesis of 1, which can advance our understanding of the programming rules of fungal PKSs.
The polyketide synthase ThiA that forms the heterotrimeric fungal depside thielavin A (1) has been identified and characterized. The thioesterase (TE) domain of ThiA was found to perform two consecutive esterification reactions as well as subsequent hydrolysis, and a plausible reaction mechanism for the TE‐catalyzed reactions has been proposed. Furthermore, this study provides insights into how ThiA selectivity yields the heterotrimeric product.
Although several chemokines play key roles in the pathogenesis of acute lung injury (ALI), the roles of chemokine (C‐X‐C motif) ligand 16 (CXCL16) and its receptor C‐X‐C chemokine receptor type 6 ...(CXCR6) in ALI pathogenesis remain to be elucidated. The mRNA and protein expression of CXCL16 and CXCR6 was detected after lipopolysaccharide (LPS) stimulation with or without treatment with the nuclear factor‐κB (NF‐κB) inhibitor pyrrolidine dithiocarbamate (PDTC). Lung injury induced by LPS was evaluated in CXCR6 knockout mice. CXCL16 level was elevated in the serum of ALI patients (n = 20) compared with healthy controls (n = 30). CXCL16 treatment (50, 100, and 200 ng/mL) in 16HBE cells significantly decreased the epithelial barrier integrity and E‐cadherin expression, and increased CXCR6 expression, reactive oxygen species (ROS) production, and p38 phosphorylation. Knockdown of CXCR6 or treatment with the p38 inhibitor SB203580 abolished the effects of CXCL16. Moreover, treatment of 16HBE cells with LPS (5, 10, 20 and 50 μg/mL) significantly increased CXCL16 release as well as the mRNA and protein levels of CXCL16 and CXCR6. The effects of LPS treatment (20 μg/mL) were abolished by treatment with PDTC. The results of the luciferase assay further demonstrated that PDTC treatment markedly inhibited the activity of the CXCL16 promoter. In conclusion, CXCL16, whose transcription was enhanced by LPS, may be involved in ROS production, epithelial barrier dysfunction and E‐cadherin down‐regulation via p38 signalling, thus contributing to the pathogenesis of ALI. Importantly, CXCR6 knockout or inhibition of p38 signalling may protect mice from LPS‐induced lung injury by decreasing E‐cadherin expression.
Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe inflammatory lung diseases. Methylprednisolone (MP) is a common drug against inflammation in clinic. In this study, ...we aim to investigate the protective effect of MP on ALI and potential mechanisms.
Male BABL/c mice were injected through tail vein using lipopolysaccharide (LPS, 5 mg/kg) with or without 5 mg/kg MP. Lung mechanics, tissue injury and inflammation were examined. Macrophage subsets in the lung were identified by flow cytometry. Macrophages were cultured from bone marrow of mice with or without MP. Then, we analyzed and isolated the subsets of macrophages. These isolated macrophages were then co-cultured with CD4
T cells, and the percentage of regulatory T cells (Tregs) was examined. The expression of IL-10 and TGF-β in the supernatant was measured. The Tregs immunosuppression function was examined by T cell proliferation assay. To disclose the mechanism of the induction of Tregs by M2c, we blocked IL-10 or/and TGF-β using neutralizing antibody.
Respiratory physiologic function was significantly improved by MP treatment. Tissue injury and inflammation were ameliorated in the MP-treated group. After MP treatment, the number of M1 decreased and M2 increased in the lung. In in vitro experiment, MP promoted M2 polarization rather than M1. We then induced M1, M2a and M2c from bone marrow cells. M1 induced more Th17 while M2 induced more CD4
CD25
Fxop3
Tregs. Compared with M2a, M2c induced more Tregs, and this effect could be blocked by anti-IL-10 and anti-TGF-β antibodies. However, M2a and M2c have no impact on Tregs immunosuppression function.
In conclusion, MP ameliorated ALI by promoting M2 polarization. M2, especially M2c, induced Tregs without any influence on Tregs immunosuppression function.
There is a bidirectional relationship between inflammatory bowel disease (IBD) and depression/anxiety. Emerging evidences indicate that the liver may be involved in microbiota-gut-brain axis. This ...experiment focused on the role of melatonin in regulating the gut microbiota and explores its mechanism on dextran sulphate sodium- (DSS-) induced neuroinflammation and liver injury. Long-term DSS-treatment increased lipopolysaccharide (LPS), proinflammation cytokines IL-1β and TNF-α, and gut leak in rats, breaking blood-brain barrier and overactivated astrocytes and microglia. Ultimately, the rats showed depression-like behavior, including reduction of sucrose preference and central time in open field test and elevation of immobility time in a forced swimming test. Oral administration with melatonin alleviated neuroinflammation and depression-like behaviors. However, melatonin supplementation did not decrease the level of LPS but increase short-chain fatty acid (SCFA) production to protect DSS-induced neuroinflammation. Additionally, western blotting analysis suggested that signaling pathways farnesoid X receptor-fibroblast growth factor 15 (FXR-FGF 15) in gut and apoptosis signal-regulating kinase 1 (ASK1) in the liver overactivated in DSS-treated rats, indicating liver metabolic disorder. Supplementation with melatonin markedly inhibited the activation of these two signaling pathways and its downstream p38. As for the gut microbiota, we found that immune response- and SCFA production-related microbiota, like Lactobacillus and Clostridium significantly increased, while bile salt hydrolase activity-related microbiota, like Streptococcus and Enterococcus, significantly decreased after melatonin supplementation. These altered microbiota were consistent with the alleviation of neuroinflammation and metabolic disorder. Taken together, our findings suggest melatonin contributes to reshape gut microbiota and improves inflammatory processes in the hippocampus (HPC) and metabolic disorders in the liver of DSS rats.
Although single-function camouflage under infrared/visible bands has made great advances, it is still difficult for camouflage materials to cope with the synergy detection spanning both visible and ...infrared spectra and adapt to complex and variable scenarios. Herein, a trilayer composite integrating thermal insulation, heat absorption, solar/electro-thermal conversions, and thermochromism is fabricated for visible and infrared dual camouflages by combining anisotropic MXene/reduced graphene oxide hybrid aerogel with the n-octadecane phase change material in its bottom and a thermochromic coating on its upper surface. Benefiting from the synergetic heat-transfer suppression derived from the thermal insulation of the porous aerogel layer and the heat absorption of the n-octadecane phase-change layer, the composite can serve as a cloak to hide the target signatures from the infrared images of its ambient surroundings during the day in the jungle and at night in all scenes and can assist the target in escaping visual surveillance by virtue of its green appearance. For desert scenarios, the composite can spontaneously increase its surface temperature via its solar-thermal energy conversion, merging infrared images of the targets into the high-temperature surroundings; meanwhile, it can vary the surface color from the original green to yellow, enabling the target to visually disappear from ambient sands and hills. This work provides a promising strategy for designing adaptive and adjustable integrated camouflage materials to counter multiband surveillance in complicated environments.
Two amorphous metal-organic frameworks (
MOFs) were obtained from crystalline Co-MOF (SCNU-Z6)
temperature-induced (
-SCNU-Z6) and water-immersed (
-SCNU-Z6) approaches. They exhibited high iodine ...uptake, with the adsorption capacities of
-SCNU-Z6 and
-SCNU-Z6 reaching 2.05 and 5.04 g g
, respectively. This work is the first report of iodine uptake by
MOFs.
Co‐based metal–organic frameworks (MOFs) as electrocatalysts for two‐electron oxygen reduction reaction (2e− ORR) are highly promising for H2O2 production, but suffer from the intrinsic ...activity‐selectivity trade‐off. Herein, we report a ZnCo bimetal‐triazole framework (ZnCo‐MTF) as high‐efficiency 2e− ORR electrocatalysts. The experimental and theoretical results demonstrate that the coordination between 1,2,3‐triazole and Co increases the antibonding‐orbital occupancy on the Co−N bond, promoting the activation of Co center. Besides, the adjacent Zn−Co sites on 1,2,3‐triazole enable an asymmetric “side‐on” adsorption mode of O2, favoring the reduction of O2 molecules and desorption of OOH* intermediate. By virtue of the unique ligand effect, the ZnCo‐MTF exhibits a 2e− ORR selectivity of ≈100 %, onset potential of 0.614 V and H2O2 production rate of 5.55 mol gcat−1 h−1, superior to the state‐of‐the‐art zeolite imidazole frameworks. Our work paves the way for the design of 2e− ORR electrocatalysts with desirable coordination and electronic structure.
A ZnCo bimetal‐triazole framework has been developed as high‐efficiency 2e− ORR electrocatalysts. The unique ligand effect of 1,2,3‐triazole optimizes the electronic structure of Co sites and enables an asymmetric “side‐on” adsorption mode of O2 molecule, resulting in an excellent 2e− ORR performance with a selectivity of ≈100 % and an H2O2 production rate of 5.55 mol gcat−1 h−1.
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