Precise determination of the structure‐property relationship of zeolite‐based metal catalysts is critical for the development toward practical applications. However, the scarcity of real‐space ...imaging of zeolite‐based low‐atomic‐number (LAN) metal materials due to the electron‐beam sensitivity of zeolites has led to continuous debates regarding the exact LAN metal configurations. Here, a low‐damage high‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) imaging technique is employed for direct visualization and determination of LAN metal (Cu) species in ZSM‐5 zeolite frameworks. The structures of the Cu species are revealed based on the microscopy evidence and also proved by the complementary spectroscopy results. The correlation between the characteristic Cu size in Cu/ZSM‐5 catalysts and their direct oxidation of methane to methanol reaction properties is unveiled. As a result, the mono‐Cu species stably anchored by Al pairs inside the zeolite channels are identified as the key structure for higher C1 oxygenates yield and methanol selectivity for direct oxidation of methane. Meanwhile, the local topological flexibility of the rigid zeolite frameworks induced by the Cu agglomeration in the channels is also revealed. This work exemplifies the combination of microscopy imaging and spectroscopy characterization serves as a complete arsenal for revealing structure‐property relationships of the supported metal‐zeolite catalysts.
A low‐damage HAADF‐STEM imaging technique is employed for direct visualization and determination of Cu species in ZSM‐5 zeolite frameworks. The structure of the Cu species are revealed based on the microscopy evidence and also proved by the complementary spectroscopy results. The mono‐Cu species stably anchored by Al pairs inside the zeolite channels are identified as the key structure for higher C1 oxygenates yield and methanol selectivity for direct oxidation of methane.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Heterogeneous catalysis plays a significant role in the modern chemical industry. Towards the rational design of novel catalysts, understanding reactions over surfaces is the most essential aspect. ...Typical industrial catalytic processes such as syngas conversion and methane utilisation can generate a large reaction network comprising thousands of intermediates and reaction pairs. This complexity not only arises from the permutation of transformations between species but also from the extra reaction channels offered by distinct surface sites. Despite the success in investigating surface reactions at the atomic scale, the huge computational expense of
ab initio
methods hinders the exploration of such complicated reaction networks. With the proliferation of catalysis studies, machine learning as an emerging tool can take advantage of the accumulated reaction data to emulate the output of
ab initio
methods towards swift reaction prediction. Here, we briefly summarise the conventional workflow of reaction prediction, including reaction network generation,
ab initio
thermodynamics and microkinetic modelling. An overview of the frequently used regression models in machine learning is presented. As a promising alternative to full
ab initio
calculations, machine learning interatomic potentials are highlighted. Furthermore, we survey applications assisted by these methods for accelerating reaction prediction, exploring reaction networks, and computational catalyst design. Finally, we envisage future directions in computationally investigating reactions and implementing machine learning algorithms in heterogeneous catalysis.
Machine learning algorithms can facilitate the reaction prediction in heterogeneous catalysis.
To explore high-performance electrocatalysts, electronic regulation on active sites is essentially demanded. Herein, we propose controlled phosphorus doping to effectively modify the electronic ...configuration of nanostructured Mo2C, accomplishing a benchmark performance of noble-metal-free electrocatalysts in the hydrogen evolution reaction (HER). Employing MoOx–phytic acid–polyaniline hybrids with tunable composition as precursors, a series of hierarchical nanowires composed of phosphorus-doped Mo2C nanoparticles evenly integrated within conducting carbon (denoted as P-Mo2C@C) are successfully obtained via facile pyrolysis under inert flow. Remarkably, P-doping into Mo2C can increase the electron density around the Fermi level of Mo2C, leading to weakened Mo–H bonding toward promoted HER kinetics. Further density functional theory calculations show that the negative hydrogen-binding free energy (ΔGH*) on pristine Mo2C gradually increases with P-doping due to electron transfer and steric hindrance by P on the Mo2C surface, indicating the effectively weakened strength of Mo–H. With optimal doping, a ΔGH* approaching 0 eV suggests a good balance between the Volmer and Heyrovsky/Tafel steps in HER kinetics. As expected, the P-Mo2C@C nanowires with controlled P-doping (P: 2.9 wt%) deliver a low overpotential of 89 mV at a current density of −10 mA cm−2 and striking kinetic metrics (onset overpotential: 35 mV, Tafel slope: 42 mV dec−1) in acidic electrolytes, outperforming most of the current noble-metal-free electrocatalysts. Elucidating feasible electronic regulation and the remarkably enhanced catalysis associated with controlled P-doping, our work will pave the way for developing efficient noble-metal-free catalysts via rational surface engineering.
Cobalt imidazolate frameworks are classical electrocatalysts for the oxygen evolution reaction (OER) but suffer from the relatively low activity. Here, a non‐3d metal modulation strategy is presented ...for enhancing the OER activity of cobalt imidazolate frameworks. Two isomorphous frameworks Co4(MO4)(eim)6 (M=Mo or W, Heim=2‐ethylimidazole) having Co(eim)3(MO4) units and high water stabilities were designed and synthesized. In different neutral media, the Mo‐modulated framework coated on a glassy carbon electrode shows the best OER performances (1 mA cm−2 at an overpotential of 210 mV in CO2‐saturated 0.5 m KHCO3 electrolyte and 2/10/22 mA cm−2 at overpotential of 388/490/570 mV in phosphate buffer solution) among non‐precious metal catalysts and even outperforms RuO2. Spectroscopic measurements and computational simulations revealed that the non‐3d metals modulate the electronic structure of Co for optimum reactant/product adsorption and tailor the energy of rate‐determining step to a more moderate value.
Non‐3D for 3D: Introducing non‐3d metal oxide units into a cobalt imidazolate framework results in the drastic enhancement of electrocatalytic performance of the oxygen evolution reaction in neutral media.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A large number of studies have explored the association between frailty and mortality among COVID-19 patients, with inconsistent results. The aim of this meta-analysis was to synthesize the evidence ...on this issue.
Three databases, PubMed, Embase, and Cochrane Library, from inception to 20th January 2021 were searched for relevant literature. The Newcastle-Ottawa Scale (NOS) was used to assess quality bias, and STATA was employed to pool the effect size by a random effects model. Additionally, potential publication bias and sensitivity analyses were performed.
Fifteen studies were included, with a total of 23,944 COVID-19 patients, for quantitative analysis. Overall, the pooled prevalence of frailty was 51% (95% CI: 44-59%). Patients with frailty who were infected with COVID-19 had an increased risk of mortality compared to those without frailty, and the pooled hazard ratio (HR) and odds ratio (OR) were 1.99 (95% CI: 1.66-2.38) and 2.48 (95% CI: 1.78-3.46), respectively. In addition, subgroup analysis based on population showed that the pooled ORs for hospitalized patients in eight studies and nursing home residents in two studies were 2.62 (95% CI: 1.68-4.07) and 2.09 (95% CI: 1.40-3.11), respectively. Subgroup analysis using the frailty assessment tool indicated that this association still existed when using the clinical frailty scale (CFS) (assessed in 6 studies, pooled OR = 2.88, 95% CI: 1.52-5.45; assessed in 5 studies, pooled HR = 1.99, 95% CI: 1.66-2.38) and other frailty tools (assessed in 4 studies, pooled OR = 1.98, 95% CI: 1.81-2.16). In addition, these significant positive associations still existed in the subgroup analysis based on study design and geographic region.
Our study indicates that frailty is an independent predictor of mortality among patients with COVID-19. Thus, frailty could be a prognostic factor for clinicians to stratify high-risk groups and remind doctors and nurses to perform early screening and corresponding interventions urgently needed to reduce mortality rates in patients infected by SARS-CoV-2.
White-light emitting organic materials attract broad attention which are ascribed to their potential for applications in lighting devices and display media. Most reported organic white-light emitters ...rely on the combination of several components that emit different colors of light (red/green/blue or orange/blue), which may cause problems to stability, reproducibility and device fabrication. By contrast, white-light emission from single-molecule systems offers opportunities to overcome these disadvantages, meanwhile engendering white-light with high quality. Nevertheless, limited cases of white-light emission at the molecular scale reported principally concentrate on organic solvents. Herein, we designed and synthesized new bi-functional organic molecules with a symmetric donor-acceptor-donor (D-A-D) type structure with the aim to construct a single-molecule white-light emitting system in aqueous solution. Further experiments and calculations demonstrate the possibility of stacking between the pyridinium-naphthalene (PN) core and coumarin groups in the designed molecules, ascribed to hydrophobic effects, π-π stacking and donor-acceptor interactions, which could dramatically enhance the intramolecular charge transfer (ICT) efficiency along with remarkable charge transfer (CT) emission. Based on this, multicolor photoluminescence including white-light can be finely tuned in various modes including excitation wavelength, solvent polarity, temperature, and host-guest interactions. A white-light emitting (WLE) hydrogel was also facilely prepared through the dispersion of one of the compounds in a commercial agarose gelator. This innovative study helps enrich the strategies to construct single-molecule organic white-light emitting materials in aqueous medium using the self-folding behavior.
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IJS, KILJ, NUK, UL, UM, UPUK
Anchoring‐based self‐assembly (ASA) has emerged as a material‐saving and highly scalable strategy to fabricate charge‐transporting monolayers for perovskite solar cells (PSCs). However, the ...interfacial hole‐extraction and electron‐blocking performances are highly dependent on the compactness of the ASA monolayers, which has been largely ignored though it is very crucial to the efficiency and stability of PSCs. Here, strategically designed hole‐transporting molecules with different anchoring groups are incorporated to investigate the effect of bonding strength on monolayer quality and correlate these with the performance of p‐i‐n structured PSCs. It is unraveled that the anchoring groups with a stronger bonding strength are advantageous for improving the assembly rate, density, and compactness of ASA monolayer, thus enhancing charge collection and suppressing interfacial recombination. The prototypical PSCs based on optimal ASA monolayer achieve a high power conversion efficiency (PCE) of 21.43% (0.09 cm2). More encouragingly, when enlarging the device area by tenfold, a comparable PCE of 20.09% (1.0 cm2) can be obtained, suggesting that the ASA strategy is practically useful for scaling‐up. The robust anchoring of the ASA monolayer also enhances devices stability, retaining 90% of initial PCE after three months. This study provides important insights into the ASA charge‐transporting monolayers for efficient and stable PSCs.
Molecular hole‐transporting materials with different anchoring groups are synthesized. The anchoring groups with a stronger bonding strength enable greatly enhanced compactness of self‐assembly monolayer, which benefits hole‐extraction and electron‐blocking in complete devices. When applied in inverted perovskite solar cells, 1 cm2 devices show a promising power conversion efficiency of over 20% with high stability.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Anaplasma capra is an emerging tickborne human pathogen initially recognized in China in 2015; it has been reported in ticks and in a wide range of domestic and wild animals worldwide. We describe ...whole-genome sequences of 2 A. capra strains from metagenomic sequencing of purified erythrocytes from infected goats in China. The genome of A. capra was the smallest among members of the genus Anaplasma. The genomes of the 2 A. capra strains contained comparable G+C content and numbers of pseudogenes with intraerythrocytic Anaplasma species. The 2 A. capra strains had 54 unique genes. The prevalence of A. capra was high among goats in the 2 endemic areas. Phylogenetic analyses revealed that the A. capra strains detected in this study were basically classified into 2 subclusters with those previously detected in Asia. Our findings clarify details of the genomic characteristics of A. capra and shed light on its genetic diversity.
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DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Photocatalytic upgrading of crucial biomass-derived intermediate chemicals (i.e., furfural alcohol, 5-hydroxymethylfurfural (HMF)) to value-added products (aldehydes and acids) was carried out on ...ultrathin CdS nanosheets (thickness ∼1 nm) decorated with nickel (Ni/CdS). More importantly, simultaneous H2 production was realized upon visible light irradiation under ambient conditions utilizing these biomass intermediates as proton sources. The remarkable difference in the rates of transformation of furfural alcohol and HMF to their corresponding aldehydes in neutral water was observed and investigated. Aided by theoretical computation, it was rationalized that the slightly stronger binding affinity of the aldehyde group in HMF to Ni/CdS resulted in the lower transformation of HMF to 2,5-diformylfuran compared to that of furfural alcohol to furfural. Nevertheless, photocatalytic oxidation of furfural alcohol and HMF under alkaline conditions led to complete transformation to the respective carboxylates with concomitant production of H2.
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IJS, KILJ, NUK, PNG, UL, UM
Plasma SARS-CoV-2 RNA may represent a viable diagnostic alternative to respiratory RNA levels, which rapidly decline after infection. Quantitative PCR with reverse transcription (RT-qPCR) reference ...assays exhibit poor performance with plasma, probably reflecting the dilution and degradation of viral RNA released into the circulation, but these issues could be addressed by analysing viral RNA packaged into extracellular vesicles. Here we describe an assay approach in which extracellular vesicles directly captured from plasma are fused with reagent-loaded liposomes to sensitively amplify and detect a SARS-CoV-2 gene target. This approach accurately identified patients with COVID-19, including challenging cases missed by RT-qPCR. SARS-CoV-2-positive extracellular vesicles were detected at day 1 post-infection, and plateaued from day 6 to the day 28 endpoint in a non-human primate model, while signal durations for 20-60 days were observed in young children. This nanotechnology approach uses a non-infectious sample and extends virus detection windows, offering a tool to support COVID-19 diagnosis in patients without SARS-CoV-2 RNA detectable in the respiratory tract.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
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