Systematic interrogation of CRISPR antimicrobials in Klebsiella pneumoniae reveals nuclease-, guide- and strain-dependent features influencing antimicrobial activity.

CRISPR-Cas systems can be utilized as programmable-spectrum antimicrobials to combat bacterial infections. However, how CRISPR nucleases perform as antimicrobials across target sites and strains remains poorly explored. Here, we address this knowledge gap by systematically interrogating the use of CRISPR antimicrobials using multidrug-resistant and hypervirulent strains of Klebsiella pneumoniae as models. Comparing different Cas nucleases, DNA-targeting nucleases outperformed RNA-targeting nucleases based on the tested targets. Focusing on AsCas12a that exhibited robust targeting across different strains, we found that the elucidated modes of escape varied widely, restraining opportunities to enhance killing. We also encountered individual guide RNAs yielding different extents of clearance across strains, which were linked to an interplay between improper gRNA folding and strain-specific DNA repair and survival. To explore features that could improve targeting across strains, we performed a genome-wide screen in different K. pneumoniae strains that yielded guide design rules and trained an algorithm for predicting guide efficiency. Finally, we showed that Cas12a antimicrobials can be exploited to eliminate K. pneumoniae when encoded in phagemids delivered by T7-like phages. Altogether, our results highlight the importance of evaluating antimicrobial activity of CRISPR antimicrobials across relevant strains and define critical parameters for efficient CRISPR-based targeting.

IgE directly affects eosinophil migration in chronic rhinosinusitis with nasal polyps through CCR3 and predicts the efficacy of omalizumab.

BACKGROUND: Whether IgE affects eosinophil migration in chronic rhinosinusitis with nasal polyps (CRSwNP) remains largely unclear. Moreover, our understanding of local IgE, eosinophils, and omalizumab efficacy in CRSwNP remains limited. OBJECTIVE: We investigated whether IgE acts directly on eosinophils and determined its role in omalizumab therapy. METHODS: Eosinophils and their surface receptors were detected by hematoxylin and eosin staining and flow cytometry. IgE and its receptors, eosinophil peroxidase (EPX), eosinophilic cationic protein, and CCR3 were detected by immunohistochemistry and immunofluorescence. Functional analyses were performed on blood eosinophils and polyp tissues. Logistic regression was performed to screen for risk factors. Receiver operating characteristic curve was generated to evaluate the accuracy. RESULTS: Both FcεRI and CD23 were expressed on eosinophils. The expression of FcεRI and CD23 on eosinophil in nasal polyp tissue was higher than in peripheral blood (both P < .001). IgE and EPX colocalized in CRSwNP. IgE directly promoted eosinophil migration by upregulating CCR3 in CRSwNP but not in healthy controls. Omalizumab and lumiliximab were found to be effective in restraining this migration, indicating CD23 was involved in IgE-induced eosinophil migration. Both IgE+ and EPX+ cells were significantly reduced after omalizumab treatment in those who experienced response (IgE+ cells, P = .001; EPX+ cells, P = .016) but not in those with no response (IgE+ cells, P = .060; EPX+ cells, P = .151). Baseline IgE+ cell levels were higher in those with response compared to those without response (P = .024). The baseline local IgE+ cell count predicted omalizumab efficacy with an accuracy of 0.811. CONCLUSIONS: IgE directly promotes eosinophil migration, and baseline local IgE+ cell counts are predictive of omalizumab efficacy in CRSwNP.

Abnormal circulating steroids refine risk of progression to heart failure in ischemic heart disease.

BACKGROUND: Patients with ischemic heart disease (IHD) experience a high incidence of progression to heart failure (HF) despite current therapies. We speculated that steroid hormone metabolic disorders distinct adverse phenotypes and contribute to HF. METHODS: We measured 18 steroids using liquid chromatography with tandem mass spectrometry in 2023 patients from the Registry Study of Biomarkers in Ischemic Heart Disease (BIOMS-IHD), including 1091 patients with IHD in a retrospective discovery set and 932 patients with IHD in a multicentre validation set. Our outcomes included incident HF after a median follow-up of 4 years. RESULTS: We demonstrated steroid-based signatures of inflammation, coronary microvascular dysfunction and left ventricular hypertrophy that were associated with subsequent HF events in patients with IHD. In both cohorts, patients with a high steroid-heart failure score (SHFS) (>1) exhibited a greater risk of incident HF than patients with a low SHFS (≤1). The SHFS further improved the prognostic accuracy beyond clinical variables (net reclassification improvement of 0.628 in the discovery set and 0.299 in the validation set) and demonstrated the maximal effect of steroid signatures in patients with IHD who had lower B-type natriuretic peptide levels (pinteraction = 0.038). CONCLUSIONS: A steroid-based strategy can simply and effectively identify individuals at higher HF risk who may derive benefit from more intensive follow-ups.

Rhodium(III)-Catalyzed C-H Cascade Annulation of Arylhydrazines with 2-Diazo-1,3-indandiones for the Synthesis of Tetracyclic Indeno[1,2-b]indoles.

An efficient approach for the preparation of tetracyclic indeno[1,2-b]indoles via Rh(III)-catalyzed C-H cascade annulation between arylhydrazines and diazo indan-1,3-diones has been established. In addition, a series of indeno[1,2-b]indoles were obtained in up to 96% yield with a wide range of substrates and high functional group tolerance. Finally, the diverse transformations of the desired products demonstrate the synthetic utility and utilization of this protocol.

Relationship between intrinsic capacity and health-related quality of life among community-dwelling older adults: the moderating role of social support.

PURPOSE: To examine how social support might moderate the relationship between intrinsic capacity and health-related quality of life (HRQoL) based on the buffering model of social support. METHODS: This was a cross-sectional study with a sample of 1181 Chinese community-dwelling older adults aged ≥ 60 years in 2016. Social support was assessed using the Social Support Rating Scale. Intrinsic capacity was assessed using the revised integrated care for older people screening tool. HRQoL was measured by the 12-item Short Form Health Survey. Hierarchical linear regression analysis was implemented to test the moderating effect of social support. RESULTS: Support utilization attenuated the relationship between lower intrinsic capacity and poor physical HRQoL while subjective support attenuated the relationship between lower intrinsic capacity and poor mental HRQoL. However, objective support had no significant moderating effect on the relationship between intrinsic capacity and specific domains of HRQoL. CONCLUSION: The moderating effects of social support on the association between intrinsic capacity and HRQoL vary by support types. Effective interventions should target the perception and utilization of available support among older adults with lower intrinsic capacity to maintain their physical and mental HRQoL.

Effectiveness of interventions for informal caregivers of community-dwelling frail older adults: A systematic review and meta-analysis.

AIM: Systematic reviews on interventions for informal caregivers of community-dwelling frail older adults were published over a decade ago and they mistook frailty for other severe age-related conditions like disability and dementia. Therefore, this study aimed to systematically synthesize these interventions supporting these caregivers identified by an acknowledged frailty assessment instrument and to examine their effectiveness on caregiver-related outcomes. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Fourteen electronic databases, grey literature and reference lists were systematically searched for randomized controlled trials (RCTs) and non-randomized controlled trials (NRCTs) from inception to November 3, 2023. METHODS: Methodology quality and risk of bias were assessed. Data were meta-analysed using the Comprehensive Meta-Analysis, version 3.0. Studies and outcomes unsuitable for meta-analysis were summarized by narrative syntheses. RESULTS: Four studies consisting of three RCTs and one NRCT were included involving 350 participants. Interventions for caregivers of frail older adults included multicomponent interventions (n = 3) and education intervention (n = 1). Interventions had a moderate effect on reducing depression and showed nonsignificant effects on caregiver burden, caregiving time or quality of life (QoL). The PEDro scores for RCTs ranged from 6 to 8, indicating good methodologic quality, but were all judged as high risk of bias. The NRCT reported all methodologic aspects and was at low risk of bias. CONCLUSIONS: Few studies focus on interventions targeting caregivers of frail older adults, and their effectiveness may vary by outcomes. This review suggested the potential benefits of these interventions in reducing caregivers' depression. IMPACT: The differential effectiveness by outcomes and high risk of bias of studies implicate that more rigorous studies are warranted.

Exploring Novel Antidepressants Targeting G Protein-Coupled Receptors and Key Membrane Receptors Based on Molecular Structures.

Major Depressive Disorder (MDD) is a complex mental disorder that involves alterations in signal transmission across multiple scales and structural abnormalities. The development of effective antidepressants (ADs) has been hindered by the dominance of monoamine hypothesis, resulting in slow progress. Traditional ADs have undesirable traits like delayed onset of action, limited efficacy, and severe side effects. Recently, two categories of fast-acting antidepressant compounds have surfaced, dissociative anesthetics S-ketamine and its metabolites, as well as psychedelics such as lysergic acid diethylamide (LSD). This has led to structural research and drug development of the receptors that they target. This review provides breakthroughs and achievements in the structure of depression-related receptors and novel ADs based on these. Cryo-electron microscopy (cryo-EM) has enabled researchers to identify the structures of membrane receptors, including the N-methyl-D-aspartate receptor (NMDAR) and the 5-hydroxytryptamine 2A (5-HT2A) receptor. These high-resolution structures can be used for the development of novel ADs using virtual drug screening (VDS). Moreover, the unique antidepressant effects of 5-HT1A receptors in various brain regions, and the pivotal roles of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) and tyrosine kinase receptor 2 (TrkB) in regulating synaptic plasticity, emphasize their potential as therapeutic targets. Using structural information, a series of highly selective ADs were designed based on the different role of receptors in MDD. These molecules have the favorable characteristics of rapid onset and low adverse drug reactions. This review offers researchers guidance and a methodological framework for the structure-based design of ADs.

Joint trajectories of loneliness, social isolation and sarcopenia and associations with adverse outcomes: A prospective cohort study.

This study aimed to examine joint trajectories of loneliness, social isolation and sarcopenia and their associations with adverse outcomes. A total of 4701 participants aged ≥60 years who had a baseline and at least one follow-up assessment of loneliness, social isolation and sarcopenia across 2011, 2013 and 2015 waves in China Health and Retirement Longitudinal Study. Adverse outcomes were obtained in 2018 wave. Joint trajectories were fit using the parallel process latent class growth analysis, and their associations with adverse outcomes were evaluated using modified Poisson regression. Joint trajectory patterns for social relationship and sarcopenia did not vary by the assessment for sarcopenia, but did vary by the assessment for social relationship. Older adults exhibit distinct joint trajectories and those with persistent combination of loneliness or social isolation and sarcopenia experience greatest risk of adverse outcomes. These findings implicate integration of health care and social care for community-dwelling older adults.

The Structure of Boron Monoxide.

Boron monoxide (BO), prepared by the thermal condensation of tetrahydroxydiboron, was first reported in 1955; however, its structure could not be determined. With the recent attention on boron-based two-dimensional materials, such as borophene and hexagonal boron nitride, there is renewed interest in BO. A large number of stable BO structures have been computationally identified, but none are supported by experiments. The consensus is that the material likely forms a boroxine-based two-dimensional material. Herein, we apply advanced 11B NMR experiments to determine the relative orientations of B(B)O2 centers in BO. We find that the material is composed of D2h-symmetric O2B-BO2 units that organize to form larger B4O2 rings. Further, powder diffraction experiments additionally reveal that these units organize to form two-dimensional layers with a random stacking pattern. This observation is in agreement with earlier density functional theory (DFT) studies that showed B4O2-based structures to be the most stable.

Two Mesoporous Domains Are Better Than One for Catalytic Deconstruction of Polyolefins.

Catalytic hydrogenolysis of polyolefins into valuable liquid, oil, or wax-like hydrocarbon chains for second-life applications is typically accompanied by the hydrogen-wasting co-formation of low value volatiles, notably methane, that increase greenhouse gas emissions. Catalytic sites confined at the bottom of mesoporous wells, under conditions in which the pore exerts the greatest influence over the mechanism, are capable of producing less gases than unconfined sites. A new architecture was designed to emphasize this pore effect, with the active platinum nanoparticles embedded between linear, hexagonal mesoporous silica and gyroidal cubic MCM-48 silica (mSiO2/Pt/MCM-48). This catalyst deconstructs polyolefins selectively into ∼C20-C40 paraffins and cleaves C-C bonds at a rate (TOF = 4.2 ± 0.3 s-1) exceeding that of materials lacking these combined features while generating negligible volatile side products including methane. The time-independent product distribution is consistent with a processive mechanism for polymer deconstruction. In contrast to time- and polymer length-dependent products obtained from non-porous catalysts, mSiO2/Pt/MCM-48 yields a C28-centered Gaussian distribution of waxy hydrocarbons from polyolefins of varying molecular weight, composition, and physical properties, including low-density polyethylene, isotactic polypropylene, ultrahigh-molecular-weight polyethylene, and mixtures of multiple, post-industrial polyolefins. Coarse-grained simulation reveals that the porous-core architecture enables the paraffins to diffuse away from the active platinum site, preventing secondary reactions that produce gases.

Sustainable, Insoluble, and Photonic Cellulose Nanocrystal Patches for Calcium Ion Sensing in Sweat.

Self-assembly of cellulose nanocrystals (CNCs) is invaluable for the development of sustainable optics and photonics. However, the functional failure of CNC-derived materials in humid or liquid environments inevitably impairs their development in biomedicine, membrane separation, environmental monitoring, and wearable devices. Here, a facile and robust method to fabricate insoluble hydrogels in a self-assembled CNC-polyvinyl alcohol (PVA) system is reported. Due to the reconstruction of inter- or intra-molecular hydrogen bond interactions, thermal dehydration makes an optimized CNC/PVA photonic film form a stable hydrogel network in an aqueous solution rather than dissolve. Notably, the resulting hydrogel exhibits superb mechanical performance (stress up to 3.3 Mpa and tough up to 0.73 MJ m-3 ) and reversible conversion between dry and wet states, enabling it convenient for specific functionalization. Sodium alginate (SA) can be adsorbed into the CNC photonic structure by swelling dry CNC/PVA film in a SA solution. The prepared hydrogel showcases the comprehensive properties of freezing resistance (-20°C), strong adhesion, satisfactory biocompatibility, and highly sensitive and selective Ca2+ sensing. The material could act as a portable wearable patch on the skin for the continuous analysis of calcium trends during different physical exercises, facilitating their development in precision nutrition and health monitoring.

Extension of high-order harmonic generation cutoff from laser-ablated tin plasma plumes.

The high-order harmonic spectra from laser-ablated tin plasma plumes are investigated experimentally and theoretically at different laser wavelengths. It is found that the harmonic cutoff is extended to ∼84 eV and the harmonic yield is greatly improved by decreasing the driving laser wavelength from 800 nm to 400 nm. Appling the Perelomov-Popov-Terent'ev theory with the semiclassical cutoff law and one-dimensional time-dependent Schrödinger equation, the contribution of the Sn3+ ion to harmonic generation accounts for the cutoff extension at 400 nm. With the qualitative analysis of the phase mismatching effect, we reveal the phase matching caused by the dispersion of free electrons is greatly optimized in the 400 nm driving field relative to the 800 nm driving field. The high-order harmonic generated from laser-ablated tin plasma plumes driven by the short laser wavelength provides a promising way to extend cutoff energy and generate intensely coherent extreme ultraviolet radiation.

Theoretical study on porphyrin arch-tapes of carbonyl-inserted seven-membered rings with high nonlinear optical properties.

Porphyrin tapes have attracted extensive attention because their fully conjugated π-networks act as nonlinear optical (NLO) materials. A family of Ni(II) and Zn(II) porphyrin arch-tapes that are connected by varying bridge (B) ligands (meso-meso ß-ß doubly linked dimer 1, meso-meso ß-ß ß-ß triply linked dimer 3, methylene-inserted dimer 2 and trimer 5, carbonyl-inserted dimer 4, trimer 6, and Zn(II) trimer 7) have been synthesized by a density functional theory (DFT) method. The results show that carbonyl-inserted arch-tapes significantly enhance second hyperpolarizability (γ), indicating that the remarkably contorted structure incorporated seven-membered ring(s) directly affect their NLO properties of our focus. Moreover, the electronic absorption spectra calculated for all studied complexes with time-dependent DFT theory (TDDFT) predict that carbonyl-inserted complex 4 contributes to a red-shift of the Q-band (160 nm) for the meso-meso ß-ß doubly linked complex 1. The third-order NLO responses and the electron transition properties strongly depend on the nature of the bridge (B) ligand, which means that an active involvement of the carbonyl group presents an advantage for its application in NLO materials.

Improvement of Acoustic Models Fused with Lip Visual Information for Low-Resource Speech.

Endangered language generally has low-resource characteristics, as an immaterial cultural resource that cannot be renewed. Automatic speech recognition (ASR) is an effective means to protect this language. However, for low-resource language, native speakers are few and labeled corpora are insufficient. ASR, thus, suffers deficiencies including high speaker dependence and over fitting, which greatly harms the accuracy of recognition. To tackle the deficiencies, the paper puts forward an approach of audiovisual speech recognition (AVSR) based on LSTM-Transformer. The approach introduces visual modality information including lip movements to reduce the dependence of acoustic models on speakers and the quantity of data. Specifically, the new approach, through the fusion of audio and visual information, enhances the expression of speakers' feature space, thus achieving the speaker adaptation that is difficult in a single modality. The approach also includes experiments on speaker dependence and evaluates to what extent audiovisual fusion is dependent on speakers. Experimental results show that the CER of AVSR is 16.9% lower than those of traditional models (optimal performance scenario), and 11.8% lower than that for lip reading. The accuracy for recognizing phonemes, especially finals, improves substantially. For recognizing initials, the accuracy improves for affricates and fricatives where the lip movements are obvious and deteriorates for stops where the lip movements are not obvious. In AVSR, the generalization onto different speakers is also better than in a single modality and the CER can drop by as much as 17.2%. Therefore, AVSR is of great significance in studying the protection and preservation of endangered languages through AI.

Association between self-efficacy and self-management behaviours among individuals at high risk for stroke: Social support acting as a mediator.

AIMS AND OBJECTIVES: To explore the association between self-efficacy and self-management by modelling three types of social support as mediators among stroke high-risk populations. BACKGROUND: Self-efficacy and social support (i.e. objective support, subjective support and support utilisation) are important for self-management among stroke high-risk populations. Self-efficacy activates three types of social support, and the effect of social support on self-management varies by types among chronic patients. Therefore, social support may act as a mediator between self-efficacy and self-management, and the mediating role may vary by types of social support. Disentangling the role of these different types of social support can guide tailored interventions. DESIGN: A cross-sectional study. METHODS: This study was conducted among 448 Chinese adults at high risk for stroke. Self-efficacy, self-management and social support were assessed using the Self-Efficacy Scale, the Stroke Self-management Scale and the Social Support Rating Scale respectively. The PROCESS SPSS Macro version 3.3, model 4 was used to explore the mediating role of different types of social support in the relationship between self-efficacy and self-management. This study followed STROBE checklist for cross-sectional studies (Appendix S1). RESULTS: Self-efficacy improved three types of social support, and subjective support and support utilisation promoted self-management, but objective support hindered self-management. The specific indirect effect of objective support and subjective support was significant but not that of support utilisation. Objective support, subjective support and support utilisation attenuated the total effect of self-efficacy on self-management by -23.8%, 23.8% and 7.7% respectively. CONCLUSIONS: Mediating effect of social support in the relationship between self-efficacy and self-management varies by type, and the positive effect of subjective support is offset by the detrimental effect of objective support. RELEVANCE TO CLINICAL PRACTICE: Among stroke high-risk populations, interventions should target objective support and subjective support as well as self-efficacy to efficiently improve their self-management.

[Manufacturing classification system for oral solid dosage forms of traditional Chinese medicines(â ¢): classification of granule dissolving behaviors].

Solubility is an important sensory quality attribute of traditional Chinese medicine(TCM) granules. In this paper, 90 batches of granules(30 batches of TCM formula granules, 30 batches of Chinese patent medicine granules and 30 batches of Japanese Kampo granules) were used as the research objects. The turbidity sensor was used to characterize the turbidity curve of the granule dissolution process. The classification system of granule dissolution behaviors was constructed from three dimensions: dissolution degree, equilibrium time, and dissolution mechanism. According to the equilibrium time, the granule dissolution rates were divided into three categories : faster(<100 s), general(101-300 s) and slow(>301 s). According to the turbidity curve profile, the granule dissolution mechanisms were classified into dissolution-controlled type(α-type), dispersion-controlled type(ß-type), and dispersion-controlled type followed by dissolution-controlled type(γ-type). The proportion of TCM formula granules, Chinese patent medicine granules and Japanese Kampo granules with complete dissolution or slight turbidity at the end of dissolution was 46.7%, 96.7%, and 10.0%. The proportion of TCM formula granules, Chinese patent medicine granules, and Japanese Kampo granules with faster dissolution rates(<100 s) was 23.3%, 26.7%, and 40.0%. The average dissolution rate of Japanese Kampo granules was faster than that of TCM formula granules, and it was slightly faster than the average dissolution rate of Chinese patent medicine granules. The dissolution mechanism of Chinese patent medicine granules was mainly α-type, while that of Japanese Kampo granules was mainly ß-type, and the three types of dissolution mechanisms of TCM formula granules accounted for a relatively average. The purpose of improving the solubility and dispersion of granules can be achieved by combining the comprehensive application of various functional excipients with the small dosage of Japanese Kampo granules and the wide addition scope of excipients. In the process of transforming TCM compound prescriptions into formulas, there is still much room for innovation in formula excipients and process optimization.

Identification of functionally important miRNA targeted genes associated with child obesity trait in genome-wide association studies.

BACKGROUND: Genome-wide association studies (GWAS) have uncovered thousands of genetic variants that are associated with complex human traits and diseases. miRNAs are single-stranded non-coding RNAs. In particular, genetic variants located in the 3'UTR region of mRNAs may play an important role in gene regulation through their interaction with miRNAs. Existing studies have not been thoroughly conducted to elucidate 3'UTR variants discovered through GWAS. The goal of this study is to analyze patterns of GWAS functional variants located in 3'UTRs about their relevance in the network between hosting genes and targeting miRNAs, and elucidate the association between the genes harboring these variants and genetic traits. METHODS: We employed MIGWAS, ANNOVAR, MEME, and DAVID software packages to annotate the variants obtained from GWAS for 31 traits and elucidate the association between their harboring genes and their related traits. We identified variants that occurred in the motif regions that may be functionally important in affecting miRNA binding. We also conducted pathway analysis and functional annotation on miRNA targeted genes harboring 3'UTR variants for a trait with the highest percentage of 3'UTR variants occurring. RESULTS: The Child Obesity trait has the highest percentage of 3'UTR variants (75%). Of the 16 genes related to the Child Obesity trait, 5 genes (ETV7, GMEB1, NFIX, ZNF566, ZBTB40) had a significant association with the term DNA-Binding (p < 0.05). EQTL analysis revealed 2 relevant tissues and 10 targeted genes associated with the Child Obesity trait. In addition, Red Blood Cells (RBC), Hemoglobin (HB), and Package Cell Volume (PCV) have overlapping variants. In particular, the PIM1 variant occurred inside the HB Motif region 37,174,641-37,174,660, and LUC7L3 variant occurred inside RBC Motif region 50,753,918-50,753,937. CONCLUSION: Variants located in 3'UTR can alter the binding affinity of miRNA and impact gene regulation, thus warranting further annotation and analysis. We have developed a bioinformatics bash pipeline to automatically annotate variants, determine the number of variants in different categories for each given trait, and check common variants across different traits. This is a valuable tool to annotate a large number of GWAS result files.

Hybrid Catalyst Coupling Single-Atom Ni and Nanoscale Cu for Efficient CO2 Electroreduction to Ethylene.

A hybrid catalyst with integrated single-atom Ni and nanoscale Cu catalytic components is reported to enhance the C-C coupling and ethylene (C2H4) production efficiency in the electrocatalytic CO2 reduction reaction (eCO2RR). The single-atom Ni anchored on high-surface-area ordered mesoporous carbon enables high-rate and selective conversion of CO2 to CO in a wide potential range, which complements the subsequent CO enrichment on Cu nanowires (NWs) for the C-C coupling to C2H4. In situ surface-enhanced infrared absorption spectroscopy (SEIRAS) confirms the substantially improved CO enrichment on Cu, once the incorporation of single-atom Ni occurs. Also, in situ X-ray absorption near-edge structure (XANES) demonstrates the structural stability of the hybrid catalyst during eCO2RR. By modulating hybrid compositions, the optimized catalyst shows 66% Faradaic efficiency (FE) in an alkaline flow cell with over 100 mA·cm-2 at -0.5 V versus reversible hydrogen electrode, leading to a five-order enhancement in C2H4 selectivity compared with single-component Cu NWs.

General Synthetic Strategy to Ordered Mesoporous Carbon Catalysts with Single-Atom Metal Sites for Electrochemical CO2 Reduction.

The electrochemical carbon dioxide reduction reaction (CO2 RR) is a transformative technology to reduce the carbon footprint of modern society. Single-site catalysts have been demonstrated as promising catalysts for CO2 RR, but general synthetic methods for catalysts with high surface area and tunable single-site metal composition still need to be developed to unambiguously investigate the structure-activity relationship crossing various metal sites. Here, a generalized coordination-condensation strategy is reported to prepare single-atom metal sites on ordered mesoporous carbon (OMC) with high surface areas (average 800 m2  g-1 ). This method is applicable to a broad range of metal sites (Fe, Co, Ni, Cu, Pt, Pd, Ru, and Rh) with loadings up to 4 wt.%. In particular, the CO2 RR to carbon monoxide (CO) Faradaic efficiency (FE) with Ni single-site OMC catalyst reaches 95%. This high FE is maintained even under large current density (>140 mA cm-2 ) and in a long-term study (14 h), which suits the urgently needed large-scale applications. Theoretical calculations suggest that the enhanced activity on single-atom Ni sites results from balanced binding energies between key intermediates, COOH and CO, for CO2 RR, as mediated by the coordination sphere.

Application of vector beams for enhanced high-order harmonics generation in laser-induced plasmas.

High-order harmonics driven by phase- and polarization-structured femtosecond pulses are unique sources of the extreme ultraviolet vortex and vector beams, which have various applications. Here, we report the generation of intense high-order harmonics during propagation of the polarization-structured vector beams (radially polarized beam, azimuthally polarized beam, and their superposition) through the laser-induced plasmas (In, C, CdS, Zns, Ag2S). Low-order harmonics became stronger with radially polarized and azimuthally polarized driving beams compared with the linearly polarized beams, which is explained on the basis of phase matching and specific properties of vector beams. Contrary to that, the resonance-enhanced harmonic generated in the indium plasma in the case of radially polarized and azimuthally polarized beams was twice weaker compared with the harmonic generated by the LP beam due to modification in the resonant transition selection rules leading to a decrease of the oscillator strength of ionic transitions. Harmonic cut-off and intensity in the case of superposition of the radially and azimuthally polarized beams were lesser compared with the cases of the individual (radially polarized and azimuthally polarized) beams.