Melt-quenched glass formation of a family of metal-carboxylate frameworks.

Metal-organic framework (MOF) glasses are an emerging class of glasses which complement traditional inorganic, organic and metallic counterparts due to their hybrid nature. Although a few zeolitic imidazolate frameworks have been made into glasses, how to melt and quench the largest subclass of MOFs, metal carboxylate frameworks, into glasses remains challenging. Here, we develop a strategy by grafting the zwitterions on the carboxylate ligands and incorporating organic acids in the framework channels to enable the glass formation. The charge delocalization of zwitterion-acid subsystem and the densely filled channels facilitate the coordination bonding mismatch and thus reduce the melting temperature. Following melt-quenching realizes the glass formation of a family of carboxylate MOFs (UiO-67, UiO-68 and DUT-5), which are usually believed to be un-meltable. Our work opens up an avenue for melt-quenching porous molecular solids into glasses.

Regulated Dual Defects of Bridging Organic and Terminal Inorganic Ligands in Iron-based Metal-Organic Framework Nodes for Efficient Photocatalytic Ammonia Synthesis.

Engineering advantageous defects to construct well-defined active sites in catalysts is promising but challenging to achieve efficient photocatalytic NH3 synthesis from N2 and H2O due to the chemical inertness of N2 molecule. Here, we report defective Fe-based metal-organic framework (MOF) photocatalysts via a non-thermal plasma-assisted synthesis strategy, where their NH3 production capability is synergistically regulated by two types of defects, namely, bridging organic ligands and terminal inorganic ligands (OH- and H2O). Specially, the optimized MIL-100(Fe) catalysts, where there are only terminal inorganic ligand defects and coexistence of dual defects, exhibit the respective 1.7- and 7.7-fold activity enhancement comparable to the pristine catalyst under visible light irradiation. As revealed by experimental and theoretical calculation results, the dual defects in the catalyst induce the formation of abundant and highly accessible coordinatively unsaturated Fe active sites and synergistically optimize their geometric and electronic structures, which favors the injection of more d-orbital electrons in Fe sites into the N2 π* antibonding orbital to achieve N2 activation and the formation of a key intermediate *NNH in the reaction. This work provides a guidance on the rational design and accurate construction of porous catalysts with precise defective structures for high-performance activation of catalytic molecules.

Identification of a new HLA-A*0201-restricted cytotoxic T lymphocyte epitope from TC2N.

Identification of cytotoxic T lymphocyte (CTL) epitopes from tumor related antigens is a promising approach for malignant tumor immunotherapy. TC2N, a recently identified tumor associated antigen from human glioblastoma, is regarded as a promising target of tumor-specific immunotherapy. As one of the most widely used histocompatibility molecules in Chinese is HLA-A*0201, we were able to identify the TC2N peptides that are provided by this molecular type. A panel of antigenic peptides produced from TC2N were predicted by using a computer tool. The binding affinities of three peptides with the highest predicted score to the HLA-A*0201 molecule were evaluated after synthesis. In vitro and in vivo stimulation of the main T-cell response against the predicted peptides. The results demonstrated that TC2N (152-160) was able to release IFN-γ and lyse U251 cells in vitro as well as in vivo by eliciting peptide-specific CTLs. Our results indicated that peptide TC2N (152-160) (RLYGSVCDL) was a novel HLA-A2.1-restricted CTL epitope capable of inducing TC2N specific CTLs in vitro. As TC2N might qualify as a viable target for immunotherapeutic approaches for patients with GBM, we speculated that the newly identified epitope RLYGSVCDL would be of potential use in peptide-based, cancer-specific immunotherapy against GBM.

A regimen based on the combination of trimethoprim/sulfamethoxazole with caspofungin and corticosteroids as a first-line therapy for patients with severe non-HIV-related pneumocystis jirovecii pneumonia: a retrospective study in a tertiary hospital.

BACKGROUND: Pneumocystis jirovecii pneumonia (PJP) is a life-threatening and severe disease in immunocompromised hosts. A synergistic regimen based on the combination of sulfamethoxazole-trimethoprim (SMX-TMP) with caspofungin and glucocorticosteroids (GCSs) may be a potential first-line therapy for PJP. Therefore, it is important to explore the efficacy and safety of this synergistic therapy for treating non-HIV-related PJP patients. METHODS: We retrospectively analysed the data of 38 patients with non-HIV-related PJP at the First Affiliated Hospital of Xi'an Jiaotong University. Patients were divided into two groups: the synergistic therapy group (ST group, n = 20) and the monotherapy group (MT group, n = 18). All patients were from the ICU and were diagnosed with severe PJP. In the ST group, all patients were treated with SMX-TMP (TMP 15-20 mg/kg per day) combined with caspofungin (70 mg as the loading dose and 50 mg/day as the maintenance dose) and a GCS (methylprednisolone 40-80 mg/day). Patients in the MT group were treated only with SMX-TMP (TMP 15-20 mg/kg per day). The clinical response, adverse events and mortality were compared between the two groups. RESULTS: The percentage of patients with a positive clinical response in the ST group was significantly greater than that in the MT group (100.00% vs. 66.70%, P = 0.005). The incidence of adverse events in the MT group was greater than that in the ST group (50.00% vs. 15.00%, P = 0.022). Furthermore, the dose of TMP and duration of fever in the ST group were markedly lower than those in the MT group (15.71 mg/kg/day vs. 18.35 mg/kg/day (P = 0.001) and 7.00 days vs. 11.50 days (P = 0.029), respectively). However, there were no significant differences in all-cause mortality or duration of hospital stay between the MT group and the ST group. CONCLUSIONS: Compared with SMZ/TMP monotherapy, synergistic therapy (SMZ-TMP combined with caspofungin and a GCS) for the treatment of non-HIV-related PJP can increase the clinical response rate, decrease the incidence of adverse events and shorten the duration of fever. These results indicate that synergistic therapy is effective and safe for treating severe non-HIV-related PJP.

Water-Mediated Selectivity Control of CH3 OH versus CO/CH4 in CO2 Photoreduction on Single-Atom Implanted Nanotube Arrays.

Controllable methanol production in artificial photosynthesis is highly desirable due to its high energy density and ease of storage. Herein, single atom Fe is implanted into TiO2 /SrTiO3 (TSr) nanotube arrays by two-step anodization and Sr-induced crystallization. The resulting Fe-TSr with both single Fe reduction centers and dominant oxidation facets (001) contributes to efficient CO2 photoreduction and water oxidation for controlled production of CH3 OH and CO/CH4 . The methanol yield can reach to 154.20 µmol gcat -1 h-1 with 98.90% selectivity by immersing all the catalyst in pure water, and the yield of CO/CH4 is 147.48 µmol gcat -1 h-1 with >99.99% selectivity when the catalyst completely outside water. This CH3 OH yield is 50 and 3 times higher than that of TiO2 and TSr and stands among all the state-of-the-art catalysts. The facile gas-solid and gas-liquid-solid phase switch can selectively control CH3 OH production from ≈0% (above H2 O) to 98.90% (in H2 O) via slowly immersing the catalyst into water, where abundant •OH and H2 O around Fe sites play important role in selective CH3 OH production. This work highlights a new insight for water-mediated CO2 photoreduction to controllably produce CH3 OH.

E3 ligase Nedd4L promotes macrophage M1 polarization and exacerbates brain damage by TRAF3/TBK1 signaling pathway after ICH in mice.

BACKGROUND: Intracerebral hemorrhage (ICH) is a serious medical problem, and promising strategy is limited. Macrophage initiated brain inflammatory injury following ICH, but the molecular mechanism had not been well identified. E3 ligase Nedd4L is implicated in the pathogenesis of the inflammatory immune response. METHODS: In the present study, we detected the levels of Nedd4L in macrophages following ICH. Furthermore, Macrophage M1 polarization, pro-inflammatory cytokine production, BBB disruption, brain water content and neurological function were examined in ICH mice. RESULTS: Here, we demonstrated that E3 ligase Nedd4L levels of macrophage increased following ICH, promoted M1 polarization inflammation by TRAF3. Nedd4L promoted BBB disruption, as well as neurological deficits. Inhibition of Nedd4L significantly attenuated M1 polarization in vivo. Inhibition of Nedd4L decreased TRAF3 and TBK1 levels, and subsequent phosphorylation of p38 and NF-κB p65 subunit following ICH. CONCLUSIONS: Our data demonstrated that Nedd4L was involved in the pathogenesis of ICH, which promoted inflammatory responses and exacerbated brain damage by TRAF3 following ICH.

Precise solid-phase synthesis of CoFe@FeOx nanoparticles for efficient polysulfide regulation in lithium/sodium-sulfur batteries.

Complex metal nanoparticles distributed uniformly on supports demonstrate distinctive physicochemical properties and thus attract a wide attention for applications. The commonly used wet chemistry methods display limitations to achieve the nanoparticle structure design and uniform dispersion simultaneously. Solid-phase synthesis serves as an interesting strategy which can achieve the fabrication of complex metal nanoparticles on supports. Herein, the solid-phase synthesis strategy is developed to precisely synthesize uniformly distributed CoFe@FeOx core@shell nanoparticles. Fe atoms are preferentially exsolved from CoFe alloy bulk to the surface and then be carburized into a FexC shell under thermal syngas atmosphere, subsequently the formed FexC shell is passivated by air, obtaining CoFe@FeOx with a CoFe alloy core and a FeOx shell. This strategy is universal for the synthesis of MFe@FeOx (M = Co, Ni, Mn). The CoFe@FeOx exhibits bifunctional effect on regulating polysulfides as the separator coating layer for Li-S and Na-S batteries. This method could be developed into solid-phase synthetic systems to construct well distributed complex metal nanoparticles.

Constructing asymmetric double-atomic sites for synergistic catalysis of electrochemical CO2 reduction.

Elucidating the synergistic catalytic mechanism between multiple active centers is of great significance for heterogeneous catalysis; however, finding the corresponding experimental evidence remains challenging owing to the complexity of catalyst structures and interface environment. Here we construct an asymmetric TeN2-CuN3 double-atomic site catalyst, which is analyzed via full-range synchrotron pair distribution function. In electrochemical CO2 reduction, the catalyst features a synergistic mechanism with the double-atomic site activating two key molecules: operando spectroscopy confirms that the Te center activates CO2, and the Cu center helps to dissociate H2O. The experimental and theoretical results reveal that the TeN2-CuN3 could cooperatively lower the energy barriers for the rate-determining step, promoting proton transfer kinetics. Therefore, the TeN2-CuN3 displays a broad potential range with high CO selectivity, improved kinetics and good stability. This work presents synthesis and characterization strategies for double-atomic site catalysts, and experimentally unveils the underpinning mechanism of synergistic catalysis.

S-Block Potassium Single-atom Electrocatalyst with K-N4 Configuration Derived from K+ /Polydopamine for Efficient Oxygen Reduction.

Currently, single-atom catalysts (SACs) research mainly focuses on transition metal atoms as active centers. Due to their delocalized s/p-bands, the s-block main group metal elements are typically regarded as catalytically inert. Herein, an s-block potassium SAC (K-N-C) with K-N4 configuration is reported for the first time, which exhibits excellent oxygen reduction reaction (ORR) activity and stability under alkaline conditions. Specifically, the half-wave potential (E1/2 ) is up to 0.908 V, and negligible changes in E1/2 are observed after 10,000 cycles. In addition, the K-N-C offers an exceptional power density of 158.1 mW cm-2 and remarkable durability up to 420 h in a Zn-air battery. Density functional theory (DFT) simulations show that K-N-C has bifunctional active K and C sites, can optimize the free energy of ORR reaction intermediates, and adjust the rate-determining steps. The crystal orbital Hamilton population (COHP) results showed that the s orbitals of K played a major role in the adsorption of intermediates, which was different from the d orbitals in transition metals. This work significantly guides the rational design and catalytic mechanism research of s-block SACs with high ORR activity.

Atomic Engineering Modulates Oxygen Reduction of Hollow Carbon Matrix Confined Single Metal-Nitrogen Sites for Zinc-Air Batteries.

The systematical understanding of metal-dependent activity in electrocatalyzing oxygen reduction reaction (ORR), a vital reaction with sluggish kinetics for zinc-air batteries, remains quite unclear. An atomic and spatial engineering modulating ORR activity over hollow carbon quasi-sphere (HCS) confined in a series of single M-N (M = Cu, Mn, Ni) sites is reported here. Based on the theoretical prediction and experimental validation, Cu-N4 site with the lowest overpotential shows a better ORR kinetics than Mn-N4 and Ni-N4 . The ORR activity of single-atom Cu center can be further improved by decreasing the coordination number of N to two, namely Cu-N2 , due to the enhancement of electrons with lower coordination structure. Benefitting from the unique spatial confinement effect of the HCS structure in modulating electronic feature of active sites, the Cu-N2 site confined in HCS also delivers highly improved ORR kinetics and activity relative to that on planner graphene. Additionally, the best catalyst holds excellent promise in the application of zinc-air batteries. The findings will pave a new way to atomically and electronically tune active sites with high efficiency for other single-atom catalysts.

Fe/Cu diatomic catalysts for electrochemical nitrate reduction to ammonia.

Electrochemical conversion of nitrate to ammonia offers an efficient approach to reducing nitrate pollutants and a potential technology for low-temperature and low-pressure ammonia synthesis. However, the process is limited by multiple competing reactions and NO3- adsorption on cathode surfaces. Here, we report a Fe/Cu diatomic catalyst on holey nitrogen-doped graphene which exhibits high catalytic activities and selectivity for ammonia production. The catalyst enables a maximum ammonia Faradaic efficiency of 92.51% (-0.3 V(RHE)) and a high NH3 yield rate of 1.08 mmol h-1 mg-1 (at - 0.5 V(RHE)). Computational and theoretical analysis reveals that a relatively strong interaction between NO3- and Fe/Cu promotes the adsorption and discharge of NO3- anions. Nitrogen-oxygen bonds are also shown to be weakened due to the existence of hetero-atomic dual sites which lowers the overall reaction barriers. The dual-site and hetero-atom strategy in this work provides a flexible design for further catalyst development and expands the electrocatalytic techniques for nitrate reduction and ammonia synthesis.

Effect of ureteral stricture in transplant kidney and choice of treatment on long-term graft survival.

BACKGROUND: To explore the risk factors of ureteral stricture in transplant kidney and the clinical effects of different treatment methods. METHODS: The 62 patients with transplant kidney ureteral stenosis as the experimental group, and another group of recipients from the same donor as the control group (n = 59 cases). The risk factors for ureteral stricture and the survival rate of transplant kidney were analyzed and compared. The 62 patients were divided into open operation, luminal operation, and magnetic compression anastomosis (MCA) operation group. The effect of the operation and the survival rate of transplant kidney among the three groups were compared. RESULTS: In our study, we found that the above differences were statistically significant in clinical data such as gender, multiple donor renal arteries, history of infection, and delayed graft function (DGF) between the two groups (P < 0.05). Urinary tract infection and DGF history were the independent risk factors for the development of ureteral stricture. The open operation had the best treatment effect and the survival rate of the transplant kidney, followed by the MCA, the stricture recurrence rate in the luminal operation was the highest. CONCLUSION: The ureteral stricture has a negative correlation with the long-term survival rate of the transplant kidney, the curative rate and long-term effect of open surgery are the best, stricture recurrence rate of luminal surgery is high, and it may require multiple operations in the future, the MCA is a new breakthrough and innovation in the treatment of ureteral stricture.

Dual-Atom Catalysts Derived from a Preorganized Covalent Organic Framework for Enhanced Electrochemical Oxygen Reduction.

Dual-atom catalysts (DAC) are deemed as promising electrocatalysts due to the abundant active sites and adjustable electronic structure, but the fabrication of well-defined DAC is still full of challenges. Herein, bonded Fe dual-atom catalysts (Fe2 DAC) with Fe2 N6 C8 O2 configuration were developed through one-step carbonization of a preorganized covalent organic framework with bimetallic Fe chelation sites (Fe2 COF). The transition from Fe2 COF to Fe2 DAC involved the dissociation of the nanoparticles and the capture of atoms by carbon defects. Benefitting from the optimized d-band center and enhanced adsorption of OOH* intermediates, Fe2 DAC exhibited outstanding oxygen reduction activity with a half-wave potential of 0.898 V vs. RHE. This work will guide more fabrication of dual-atom and even cluster catalysts from preorganized COF in the future.

Single-atomic-site platinum steers photogenerated charge carrier lifetime of hematite nanoflakes for photoelectrochemical water splitting.

Although much effort has been devoted to improving photoelectrochemical water splitting of hematite (α-Fe2O3) due to its high theoretical solar-to-hydrogen conversion efficiency of 15.5%, the low applied bias photon-to-current efficiency remains a huge challenge for practical applications. Herein, we introduce single platinum atom sites coordination with oxygen atom (Pt-O/Pt-O-Fe) sites into single crystalline α-Fe2O3 nanoflakes photoanodes (SAs Pt:Fe2O3-Ov). The single-atom Pt doping of α-Fe2O3 can induce few electron trapping sites, enhance carrier separation capability, and boost charge transfer lifetime in the bulk structure as well as improve charge carrier injection efficiency at the semiconductor/electrolyte interface. Further introduction of surface oxygen vacancies can suppress charge carrier recombination and promote surface reaction kinetics, especially at low potential. Accordingly, the optimum SAs Pt:Fe2O3-Ov photoanode exhibits the photoelectrochemical performance of 3.65 and 5.30 mA cm-2 at 1.23 and 1.5 VRHE, respectively, with an applied bias photon-to-current efficiency of 0.68% for the hematite-based photoanodes. This study opens an avenue for designing highly efficient atomic-level engineering on single crystalline semiconductors for feasible photoelectrochemical applications.

Fabricating strong and tough aramid fibers by small addition of carbon nanotubes.

Synthetic high-performance fibers present excellent mechanical properties and promising applications in the impact protection field. However, fabricating fibers with high strength and high toughness is challenging due to their intrinsic conflicts. Herein, we report a simultaneous improvement in strength, toughness, and modulus of heterocyclic aramid fibers by 26%, 66%, and 13%, respectively, via polymerizing a small amount (0.05 wt%) of short aminated single-walled carbon nanotubes (SWNTs), achieving a tensile strength of 6.44 ± 0.11 GPa, a toughness of 184.0 ± 11.4 MJ m-3, and a Young's modulus of 141.7 ± 4.0 GPa. Mechanism analyses reveal that short aminated SWNTs improve the crystallinity and orientation degree by affecting the structures of heterocyclic aramid chains around SWNTs, and in situ polymerization increases the interfacial interaction therein to promote stress transfer and suppress strain localization. These two effects account for the simultaneous improvement in strength and toughness.

Boosting Electroreduction Kinetics of Nitrogen to Ammonia via Atomically Dispersed Sn Protuberance.

Atomically dispersed metal catalysts show potential advantages in N2 reduction reaction (NRR) due to their excellent activity and efficient metal utilization. Unfortunately, the reported catalysts usually exhibit unsatisfactory NRR activity due to their poor N2 adsorption and activation. Herein, we report a novel Sn atomically dispersed protuberance (ADP) by coordination with substrate C and O to induce positive charge accumulation on Sn site for improving its N2 adsorption, activation and NRR performance. The extended X-ray absorption fine structure (EXAFS) spectra confirmed the local coordination structure of the Sn ADPs. NRR activity was significantly promoted via Sn ADPs, exhibiting a remarkable NH3 yield (RNH3 ) of 28.3 µg h-1 mgcat -1 (7447 µg h-1 mgSn -1 ) at -0.3 V. Furthermore, the enhanced N2 Hx intermediates was verified by in situ experiments, yielding consistent results with DFT calculation. This work opens a new avenue to regulate the activity and selectivity of N2 fixation.

Circulating microRNAs as promising testicular translatable safety biomarkers: current state and future perspectives.

Drug-induced testicular injury (DITI) is one of the often-observed and challenging safety issues seen during drug development. Semen analysis and circulating hormones currently utilized have significant gaps in their ability to detect testicular damage accurately. In addition, no biomarkers enable a mechanistic understanding of the damage to the different regions of the testis, such as seminiferous tubules, Sertoli, and Leydig cells. MicroRNAs (miRNAs) are a class of non-coding RNAs that modulate gene expression post-transcriptionally and have been indicated to regulate a wide range of biological pathways. Circulating miRNAs can be measured in the body fluids due to tissue-specific cell injury/damage or toxicant exposure. Therefore, these circulating miRNAs have become attractive and promising non-invasive biomarkers for assessing drug-induced testicular injury, with several reports on their use as safety biomarkers for monitoring testicular damage in preclinical species. Leveraging emerging tools such as 'organs-on-chips' that can emulate the human organ's physiological environment and function is starting to enable biomarker discovery, validation, and clinical translation for regulatory qualification and implementation in drug development.

Suppression of kernel vibrations by layer-by-layer ligand engineering boosts photoluminescence efficiency of gold nanoclusters.

The restriction of structural vibration has assumed great importance in attaining bright emission of luminescent metal nanoclusters (NCs), where tremendous efforts are devoted to manipulating the surface landscape yet remain challenges for modulation of the structural vibration of the metal kernel. Here, we report efficient suppression of kernel vibration achieving enhancement in emission intensity, by rigidifying the surface of metal NCs and propagating as-developed strains into the metal core. Specifically, a layer-by-layer triple-ligands surface engineering is deployed to allow the solution-phase Au NCs with strong metal core-dictated fluorescence, up to the high absolute quantum yields of 90.3 ± 3.5%. The as-rigidified surface imposed by synergistic supramolecular interactions greatly influences the low-frequency acoustic vibration of the metal kernel, resulting in a subtle change in vibration frequency but a reduction in amplitude of oscillation. This scenario therewith impedes the non-radiative relaxation of electron dynamics, rendering the Au NCs with strong emission. The presented study exemplifies the linkage between surface chemistry and core-state emission of metal NCs, and proposes a strategy for brighter emitting metal NCs by regulating their interior metal core-involved motion.

Influence of ligand substitution and the solvent effect on the structures and magnetic properties of dinuclear Dy2 supramolecular architectures constructed with the bis-ß-diketonate-Dy2 building block as a metalloligand.

Based on the bis-ß-diketonate-Dy2 metalloligand [Dy2(pbth)4]·2Et3N (1, pbth = (3z,3'z)-4,4'-(1,3-phenylene)bis(1,1,1-trifluoro-4-hydroxybut-3-en-2-one)), six dinuclear complexes with eight-coordinated geometries were synthesized solvothermally through different capping N-donor coligands or solvent systems. These complexes are namely [Dy2(pbth)3(Phen)2]·2C2H5OH (2), [Dy2(pbth)3(BPhen)2]·2C2H5OH (3), [Dy2(pbth)3(Dppz)2]·2C2H5OH (4), [Dy2(pbth)3(Dppz)2]·2CH3OH (4a), [Dy2(pbth)3(4-Dmbp)2]·CH3OH·C2H5OH (5) and [Dy2(pbth)3(5-Dmbp)2]·CH3OH (6) (Phen = 1,10-phenanthroline, BPhen = 4,7-diphenyl-1,10-phenanthroline, dppz = dipyrido [3,2-a:2',3'-c] phenazine, 4-Dmbp = 4,4'-dimethyl-2,2'-bipyridyl, 5-Dmbp = 5,5'-dimethyl-2,2'-bipyridyl), respectively. In the synthetic processes of 2-6, one of four bis-ß-diketonate ligands in the metalloligand is replaced by two capping N-donor coligands. The coordination geometries, metal distances and M-L-M torsion angles of the synthesized complexes are perceptibly fine-tuned by the modification of the capping N-donor coligands or the latticed solvent molecules. Systematic magnetic investigations indicate the different magnetic relaxation dynamics of 1-6. Complex 1 displays no characteristics of single-molecule magnets (SMMs), while complexes 2-6 exhibit SMM behaviours in the absence of a static magnetic field. Complexes 2 and 3 possess effective energy barriers (Ueff) of 110.18 (2) K and 133.21 (4) K, respectively. Theoretical analysis based on ab initio calculation provides some interpretations of experimental observation.