Selenium-GPX4 axis protects follicular helper T cells from ferroptosis.

Follicular helper T (TFH) cells are a specialized subset of CD4+ T cells that essentially support germinal center responses where high-affinity and long-lived humoral immunity is generated. The regulation of TFH cell survival remains unclear. Here we report that TFH cells show intensified lipid peroxidation and altered mitochondrial morphology, resembling the features of ferroptosis, a form of programmed cell death that is driven by iron-dependent accumulation of lipid peroxidation. Glutathione peroxidase 4 (GPX4) is the major lipid peroxidation scavenger and is necessary for TFH cell survival. The deletion of GPX4 in T cells selectively abrogated TFH cells and germinal center responses in immunized mice. Selenium supplementation enhanced GPX4 expression in T cells, increased TFH cell numbers and promoted antibody responses in immunized mice and young adults after influenza vaccination. Our findings reveal the central role of the selenium-GPX4-ferroptosis axis in regulating TFH homeostasis, which can be targeted to enhance TFH cell function in infection and following vaccination.

Boosted hydrogen evolution kinetics of heteroatom-doped carbons with isolated Zn as an accelerant.

Carbon-based single-atom catalysts, a promising candidate in electrocatalysis, offer insights into electron-donating effects of metal center on adjacent atoms. Herein, we present a practical strategy to rationally design a model catalyst with a single zinc (Zn) atom coordinated with nitrogen and sulfur atoms in a multilevel carbon matrix. The Zn site exhibits an atomic interface configuration of ZnN4S1, where Zn's electron injection effect enables thermal-neutral hydrogen adsorption on neighboring atoms, pushing the activity boundaries of carbon electrocatalysts toward electrochemical hydrogen evolution to an unprecedented level. Experimental and theoretical analyses confirm the low-barrier Volmer-Tafel mechanism of proton reduction, while the multishell hollow structures facilitate the hydrogen evolution even at high current intensities. This work provides insights for understanding the actual active species during hydrogen evolution reaction and paves the way for designing high-performance electrocatalysts.

Defect-Induced All-Solid-State Frustrated Lewis Pair on Metal-Organic Monolayer Accelerating Photocatalytic CO2 Reduction with H2O Vapor.

Understanding the structure-performance relationships of a frustrated Lewis pair (FLP) at the atomic level is key to yielding high efficiency in activating chemically "inert" molecules into value-added products. A sound strategy was developed herein through incorporating oxygen defects into a Zr-based metal-organic layer (Zr-MOL-D) and employing Lewis basic proximal surface hydroxyls for the in situ formation of solid heterogeneous FLP (Zr4-δ-VO-Zr-OH). Zr-MOL-D exhibits a superior CO2 to CO conversion rate of 49.4 µmol g-1 h-1 in water vapor without any sacrificing agent or photosensitizer, which is about 12 times higher than that of pure MOL (Zr-MOL-P), with extreme stability even after being placed for half a year. Theoretical and experimental results reveal that the introduction of FLP converts the process of the crucial intermediate COOH* from an endothermic reaction to an exothermic spontaneous reaction. This work is expected to provide new prospects for developing efficient MOL-based photocatalysts in FLP chemistry through a sound defect-engineering strategy.

Phase Engineering of Zirconium MOFs Enables Efficient Osmotic Energy Conversion: Structural Evolution Unveiled by Direct Imaging.

Creating structural defects in a controlled manner within metal-organic frameworks (MOFs) poses a significant challenge for synthesis, and concurrently, identifying the types and distributions of these defects is also a formidable task for characterization. In this study, we demonstrate that by employing 2-sulfonylterephthalic acid as the ligand for synthesizing Zr (or Hf)-based MOFs, a crystal phase transformation from the common fcu topology to the rare jmt topology can be easily facilitated using a straightforward mixed-solvent strategy. The jmt phase, characterized by an extensively open framework, can be considered a derivative of the fcu phase, generated through the introduction of missing-cluster defects. We have explicitly identified both MOF phases, their intermediate states, and the novel core-shell structures they form using ultralow-dose high-resolution transmission electron microscopy. In addition to facilitating phase engineering, the incorporation of sulfonic groups in MOFs imparts ionic selectivity, making them applicable for osmotic energy harvesting through mixed matrix membrane fabrication. The membrane containing the jmt-phase MOF exhibits an exceptionally high peak power density of 10.08 W m-2 under a 50-fold salinity gradient (NaCl: 0.5 M|0.01 M), which surpasses the threshold of 5 W m-2 for commercial applications and can be attributed to the combination of large pore size, extensive porosity, and abundant sulfonic groups in this novel MOF material.

Carboxyl-Decorated UiO-66 Supporting Pd Nanoparticles for Efficient Room-Temperature Hydrodeoxygenation of Lignin Derivatives.

Hydrodeoxygenation (HDO) of lignin derivatives at room-temperature (RT) is still of challenge due to the lack of satisfactory activity reported in previous literature. Here, it is successfully designed a Pd/UiO-66-(COOH)2 catalyst by using UiO-66-(COOH)2 as the support with uncoordinated carboxyl groups. This catalyst, featuring a moderate Pd loading, exhibited exceptional activity in RT HDO of vanillin (VAN, a typical model lignin derivative) to 2-methoxyl-4-methylpheonol (MMP), and >99% VAN conversion with >99% MMP yield is achieved, which is the first metal-organic framework (MOF)-based catalyst realizing the goal of RT HDO of lignin derivatives, surpassing previous reports in the literature. Detailed investigations reveal a linear relationship between the amount of uncoordinated carboxyl group and MMP yield. These uncoordinated carboxyl groups accelerate the conversion of intermediate such as vanillyl alcohol (VAL), ultimately leading to a higher yield of MMP over Pd/UiO-66-(COOH)2 catalyst. Furthermore, Pd/UiO-66-(COOH)2 catalyst also exhibits exceptional reusability and excellent substrate generality, highlighting its promising potential for further biomass utilization.

A 2D Metal-Free Inorganic Covalent Framework: Synthesis, Crystal Structure, and Room-Temperature Phosphorescence.

The synthesis, crystal structure and room-temperature phosphorescence (RTP) of a 2D metal-free inorganic covalent framework ((H2en) [B5O8(OH)], named as CityU-12, and en represents for ethylenediamine) are reported. The precise structure information of CityU-12 has been disclosed through both single-crystal X-ray diffraction (SCXRD) analysis and low-dose high-resolution transmission electron microscopy (LD-HRTEM) study. The SCXRD results show that CityU-12 composes of 2D anionic B─O-based covalent inorganic frameworks with protonated ethylenediamine locating in the pore sites of 2D B─O layers while LD-HRTEM suggests that CityU-12 has an interplanar distance of 0.60 nm for (00 2 ¯ $\bar{2}$ ) crystal plane and 0.60 nm for (10 1 ¯ $\bar{1}$ ) crystal plane. The optical studies show that CityU-12 is an excellent nonconventional RTP material with the emission peak at 530 nm and a lifetime of 1.5 s. The quantum yield is 84.6% and the afterglow time is as long as 2.5 s. This work demonstrates that metal-free B─O frameworks can be promising nonconventional phosphors for RTP.

Tuning Main Group Element-based Metal-Organic Framework to Boost Electrocatalytic Nitrogen Reduction Under Ambient Conditions.

Main group element-based materials are emerging catalysts for ammonia (NH3 ) production via a sustainable electrochemical nitrogen reduction reaction (N2 RR) pathway under ambient conditions. However, their N2 RR performances are less explored due to the limited active behavior and unclear mechanism. Here, an aluminum-based defective metal-organic framework (MOF), aluminum-fumarate (Al-Fum), is investigated. As a proof of concept, the pristine Al-Fum MOF is synthesized by the solvothermal reaction process, and the defect engineering method namely solvent-assisted linker exchange, is applied to create the defective Al sites. The defective Al sites play an important role in ensuring the N2 RR activity for defective Al-Fum. It is found that only the defective Al-Fum enables stable and effective electrochemical N2 RR, in terms of the highest production rate of 53.9 µg(NH3 ) h-1 mgcat -1 (in 0.4 m K2 SO4 ) and the Faradaic efficiency of 73.8% (in 0.1 m K2 SO4 ) at -0.15 V vs reversible hydrogen electrode) under ambient conditions. Density functional theory calculations confirm that the N2 activation can be achieved on the defective Al sites. Such sites also allow the subsequent protonation process via the alternating associative mechanism. This defect characteristic gives the main group Al-based MOFs the ability to serve as promising electrocatalysts for N2 RR and other attractive applications.

Eliminating lattice defects in metal-organic framework molecular-sieving membranes.

Metal-organic framework (MOF) membranes are energy-efficient candidates for molecular separations, but it remains a considerable challenge to eliminate defects at the atomic scale. The enlargement of pores due to defects reduces the molecular-sieving performance in separations and hampers the wider application of MOF membranes, especially for liquid separations, owing to insufficient stability. Here we report the elimination of lattice defects in MOF membranes based on a high-probability theoretical coordination strategy that creates sufficient chemical potential to overcome the steric hindrance that occurs when completely connecting ligands to metal clusters. Lattice defect elimination is observed by real-space high-resolution transmission electron microscopy and studied with a mathematical model and density functional theory calculations. This leads to a family of high-connectivity MOF membranes that possess ångström-sized lattice apertures that realize high and stable separation performance for gases, water desalination and an organic solvent azeotrope. Our strategy could enable a platform for the regulation of nanoconfined molecular transport in MOF pores.

Precise molecular sieving of ethylene from ethane using triptycene-derived submicroporous carbon membranes.

Replacement or debottlenecking of the extremely energy-intensive cryogenic distillation technology for the separation of ethylene from ethane has been a long-standing challenge. Membrane technology could be a desirable alternative with potentially lower energy consumption. However, the current key obstacle for industrial implementation of membrane technology is the low mixed-gas selectivity of polymeric, inorganic or hybrid membrane materials, arising from the similar sizes of ethylene (3.75 Å) and ethane (3.85 Å). Here we report precise molecular sieving and plasticization-resistant carbon membranes made by pyrolysing a shape-persistent three-dimensional triptycene-based ladder polymer of intrinsic microporosity with unparalleled mixed-gas performance for ethylene/ethane separation, with a selectivity of ~100 at 10 bar feed pressure, and with long-term continuous stability for 30 days demonstrated. These submicroporous carbon membranes offer opportunities for membrane technology in a wide range of notoriously difficult separation applications in the petrochemical and natural gas industry.

Unit-cell-thick zeolitic imidazolate framework films for membrane application.

Zeolitic imidazolate frameworks (ZIFs) are a subset of metal-organic frameworks with more than 200 characterized crystalline and amorphous networks made of divalent transition metal centres (for example, Zn2+ and Co2+) linked by imidazolate linkers. ZIF thin films have been intensively pursued, motivated by the desire to prepare membranes for selective gas and liquid separations. To achieve membranes with high throughput, as in ångström-scale biological channels with nanometre-scale path lengths, ZIF films with the minimum possible thickness-down to just one unit cell-are highly desired. However, the state-of-the-art methods yield membranes where ZIF films have thickness exceeding 50 nm. Here we report a crystallization method from ultradilute precursor mixtures, which exploits registry with the underlying crystalline substrate, yielding (within minutes) crystalline ZIF films with thickness down to that of a single structural building unit (2 nm). The film crystallized on graphene has a rigid aperture made of a six-membered zinc imidazolate coordination ring, enabling high-permselective H2 separation performance. The method reported here will probably accelerate the development of two-dimensional metal-organic framework films for efficient membrane separation.

Borosilicate-Based Framework: Synthesis, Single-Crystal Structure Study, and Physical Properties.

Herein, we report the synthesis, crystal structure, and optical properties of a metal-free three-dimensional (3D) inorganic covalent framework ((H2en)[Si(B4O9)], named CityU-11, where H2en is the abbreviation for ethanediamine). With the assistance of a tiny amount of F- ions and the selection of SiO2 as Si sources, single crystals of CityU-11 can be successfully prepared under solvothermal conditions. The precise structure information on CityU-11 has been disclosed through both single-crystal X-ray diffraction (SCXRD) and low-dose high-resolution transmission electron microscopy (LD-HRTEM). The SCXRD results showed that CityU-11 crystallized in the noncentrosymmetric space group of Pnn2, while LD-HRTEM suggested that CityU-11 possessed almost the same interplanar distances of 0.6 nm for both (200) and (020) crystal planes, which finely matched with the double peaks of 2θ = 15° in the pattern of its powder X-ray diffraction (PXRD). CityU-11 also displayed an interesting optical property with a moderate birefringence of 0.0258@550 nm.

Integrating Network Pharmacology and In Vitro Experimental Verification Revealing Bushenhuoxue Recipe Against Intrauterine Adhesions via PI3K-AKT Signaling Pathway.

We aimed to investigate therapeutic effect of Bushenhuoxue recipe in intrauterine adhesions (IUA) and explore the underlying molecular mechanism via integrating network pharmacology and in vitro experimental verification. The active compounds and gene targets of Bushenhuoxue recipe were screened in the TCMSP database and the IUA-related genes were identified using GeneCards database by the keyword "Intrauterine adhesions". Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were conducted to reveal the underlying molecular mechanism of Bushenhuoxue recipe treating IUA. T-HESC cells were inducted to fibrotic state using TGF-ß1 of 10 ng/ml concentration treating for 24 h. RT-qPCR or western blot was used to demonstrate the expression levels of fibrosis markers (COL1A1 and α-SMA) and KEGG pathway markers. Cell counting kit-8 (CCK8) assay was performed to illustrate the cell viability of endometrial stromal cell. The treatment of Bushenhuoxue recipe could significantly inhibit the proliferation and fibrosis of endometrial stromal cells. We obtained a total of 169 no-repeat ingredients of Bushenhuoxue recipe and 3044 corresponding targets. After taking intersection with 4230 no-repeat IUA-related genes, a total of 83 target genes related to both Bushenhuoxue recipe and IUA were finally identified. KEGG analysis found that PI3K-AKT signaling pathway might be the key pathway. Further experiment revealed that PI3K-AKT signaling pathway was significantly activated in endometrial stromal cells of fibrotic state and the treatment of Bushenhuoxue recipe could inhibit the PI3K-AKT signaling pathway. Further rescue assay demonstrated that Bushenhuoxue recipe suppressed the proliferation and fibrosis of endometrial stromal cells via PI3K-AKT signaling pathway. Bushenhuoxue recipe suppresses the proliferation and fibrosis of endometrial stromal cells via PI3K-AKT signaling pathway, eventually inhibiting the progression of IUA.

Perturbated glucose metabolism augments epithelial cell proinflammatory function in chronic rhinosinusitis.

BACKGROUND: Glucose concentrations are increased in nasal secretions in chronic rhinosinusitis (CRS). However, the glucose metabolism and its contribution to disease pathogenesis in CRS remain unexplored. OBJECTIVES: We sought to explore the glucose metabolism and its effect on the function of nasal epithelial cells in CRS with and without nasal polyps (CRSwNP and CRSsNP). METHODS: Glucose metabolites were detected with mass spectrometry. The mRNA levels of glucose transporters (GLUTs), metabolic enzymes, and inflammatory mediators were detected by quantitative RT-PCR. The protein expression of GLUTs was studied by immunofluorescence staining, Western blotting, and flow cytometry. Glucose uptake was measured by using fluorescent glucose analog. Human nasal epithelial cells (HNECs) were cultured. Bioenergetic analysis was performed with Seahorse XF analyzer. Gene expression in HNECs was profiled by RNA sequencing. RESULTS: Increased glucose concentrations in nasal secretions was confirmed in both CRSsNP and CRSwNP. GLUT4, GLUT10, and GLUT11 were abundantly expressed in HNECs, whose expression was upregulated by inflammatory cytokines and D-glucose and was increased in CRS. Glucose uptake, glycolysis and tricarboxylic acid cycle metabolites, metabolic enzymes, and extracellular acidification rate and oxygen consumption rates were increased in HNECs in CRSsNP and CRSwNP, with a predominant shift to glycolysis. HNECs treated with high-level apical D-glucose showed enhanced glucose uptake, predominant glycolysis, and upregulated production of IL-1α, IL-1ß, TNF-α, CCL20, and CXCL8, which was suppressed by 2-deoxy-D-glucose, an inhibitor of glycolysis. CONCLUSIONS: Increased glucose in nasal secretions promotes glucose uptake and predominant glycolysis in epithelial cells, augmenting the proinflammatory function of epithelial cells in CRS.

Correlating Structural Disorder in Metal (Oxy)hydroxides and Catalytic Activity in Electrocatalytic Oxygen Evolution.

Understanding the correlation between the structural evolution of electrocatalysts and their catalytic activity is both essential and challenging. In this study, we investigate this correlation in the context of the oxygen evolution reaction (OER) by examining the influence of structural disorder during and after dynamic structural evolution on the OER activity of Fe-Ni (oxy)hydroxide catalysts using operando X-ray absorption spectroscopy, alongside other experiments and theoretical calculations. The Debye-Waller factors obtained from extended X-ray absorption fine structure analyses reflect the degree of structural disorder and exhibit a robust correlation with the intrinsic OER activities of the electrocatalysts. The enhanced OER activity of in situ-generated metal (oxy)hydroxides derived from different pre-catalysts is linked to increased structural disorder, offering a promising approach for designing efficient OER electrocatalysts. This strategy may inspire similar investigations in related electrocatalytic energy-conversion systems.

High-performance Piezoelectric Two-dimensional Covalent Organic Frameworks.

Organic piezoelectric nanogenerators (PENGs) are attractive in harvesting mechanical energy for various self-powering systems. However, their practical applications are severely restricted by their low output open circuit voltage. To address this issue, herein, we prepared two two-dimensional (2D) covalent organic frameworks (COFs, CityU-13 and CityU-14), functionalized with fluorinated alkyl chains for PENGs. The piezoelectricity of both COFs was evidenced by switchable polarization, characteristic butterfly amplitude loops, phase hysteresis loops, conspicuous surface potentials and high piezoelectric coefficient value (d33). The PENGs fabricated with COFs displayed highest output open circuit voltages (60 V for CityU-13 and 50 V for CityU-14) and delivered satisfactory short circuit current with an excellent stability of over 600 seconds. The superior open circuit voltages of CityU-13 and CityU-14 rank in top 1 and 2 among all reported organic materials-based PENGs.

Construction of Crystalline Nitrone-Linked Covalent Organic Frameworks Via Kröhnke Oxidation.

Developing diverse synthetic routes to prepare various crystalline covalent organic frameworks (COFs) and enrich the family of COFs is very important and highly desirable. In this research, we demonstrate that Kröhnke oxidation (originally developed to prepare carbonyl compounds) can be employed as an efficient method to construct two crystalline nitrone-linked COFs (CityU-1 and CityU-2) through the ingenious design of the polynitroso-containing precursors as well as the exquisite control of the polymerization conditions. The formation and structure of nitrone-based linkage units have been confirmed through a mode reaction. The as-obtained crystalline COFs have been characterized by Fourier transform infrared and X-ray photoelectron spectroscopy, powder X-ray diffraction patterns, and scanning electron microscopy. Notably, CityU-1 exhibits a BET specific surface area of 497.9 m2g-1 with an I2 capture capacity of 3.0 g g-1 at 75 °C. Our research would provide more chances to prepare various crystalline COFs for diverse applications.

Enhanced CO2 Electroreduction Selectivity toward Ethylene on Pyrazolate-Stabilized Asymmetric Ni-Cu Hybrid Sites.

Metal-organic frameworks (MOFs) possess well-defined, designable structures, holding great potential in enhancing product selectivity for electrochemical CO2 reduction (CO2R) through active site engineering. Here, we report a novel MOF catalyst featuring pyrazolate-stabilized asymmetric Ni/Cu sites, which not only maintains structural stability under harsh electrochemical conditions but also exhibits extraordinarily high ethylene (C2H4) selectivity during CO2R. At a cathode potential of -1.3 V versus RHE, our MOF catalyst, denoted as Cu1Ni-BDP, manifests a C2H4 Faradaic efficiency (FE) of 52.7% with an overall current density of 0.53 A cm-2 in 1.0 M KOH electrolyte, surpassing that on prevailing Cu-based catalysts. More remarkably, the Cu1Ni-BDP MOF exhibits a stable performance with only 4.5% reduction in C2H4 FE during 25 h of CO2 electrolysis. A suite of characterization tools─such as high-resolution transmission electron microscopy, X-ray absorption spectroscopy, operando X-ray diffraction, and infrared spectroscopy─and density functional theory calculations collectively reveal that the cubic pyrazolate-metal coordination structure and the asymmetric Ni-Cu sites in the MOF catalyst synergistically facilitate the stable formation of C2H4 from CO2.

Ultra-Highly Active Ni-Doped MOF-5 Heterogeneous Catalysts for Ethylene Dimerization.

Here, an ultra-highly active Ni-MOF-5 catalyst with high Ni loading for ethylene dimerization is reported. The Ni-MOF-5 catalysts are synthesized by a facile one-pot co-precipitation method at room temperature, where Ni2+ replaces Zn2+ in MOF-5. Unlike Zn2+ with tetrahedral coordination in MOF-5, Ni2+ is coordinated with extra solvent molecules except for four-oxygen from the framework. After removing coordinated solvent molecules, Ni-MOF-5 achieves an ethylene turnover frequency of 352 000 h-1 , corresponding to 9040 g of product per gram of catalyst per hour, at 35 °C and 50 bar, far exceeding the activities of all reported heterogeneous catalysts. The high Ni loading and full exposure structure account for the excellent catalytic performance. Isotope labeling experiments reveal that the catalytic process follows the Cossee-Arlman mechanism, rationalizing the high activity and selectivity of the catalyst. These results demonstrate that Ni-MOF-5 catalysts are very promising for industrial catalytic ethylene dimerization.

Wafer-scale single-crystal monolayer graphene grown on sapphire substrate.

The growth of inch-scale high-quality graphene on insulating substrates is desirable for electronic and optoelectronic applications, but remains challenging due to the lack of metal catalysis. Here we demonstrate the wafer-scale synthesis of adlayer-free ultra-flat single-crystal monolayer graphene on sapphire substrates. We converted polycrystalline Cu foil placed on Al2O3(0001) into single-crystal Cu(111) film via annealing, and then achieved epitaxial growth of graphene at the interface between Cu(111) and Al2O3(0001) by multi-cycle plasma etching-assisted-chemical vapour deposition. Immersion in liquid nitrogen followed by rapid heating causes the Cu(111) film to bulge and peel off easily, while the graphene film remains on the sapphire substrate without degradation. Field-effect transistors fabricated on as-grown graphene exhibited good electronic transport properties with high carrier mobilities. This work breaks a bottleneck of synthesizing wafer-scale single-crystal monolayer graphene on insulating substrates and could contribute to next-generation graphene-based nanodevices.