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A CsPbBr3@Ag-C3N4 ternary heterojunction photocatalyst with g-C3N4 as ballistic electron transport "tunnel" is designed and synthesized. The photogenerated electrons of CsPbBr3 dots can be efficiently transferred to Ag nanoparticles via g-C3N4 sheets, resulting in efficient CO2 reduction. The structured design of catalyst provides a novel insight for the development of perovskite-based photocatalysts. [Display omitted] • CsPbBr 3 @Ag-C 3 N 4 ternary heterojunction photocatalyst is designed and synthesized. • The photogenerated electrons of CsPbBr 3 QDs can be efficiently transferred to Ag nanoparticles via g-C 3 N 4 as the electron transport tunnel. • The CsPbBr 3 @Ag-C 3 N 4 ternary photocatalyst achieves a conversion rate of 19.49 μmol·g−1·h−1 with almost 100 % CO selectivity. • In situ DRIFT and DFT calculations reveal the photocatalytic mechanism for CO 2 reduction. Perovskite CsPbBr 3 quantum dot shows great potential in artificial photosynthesis, attributed to its outstanding optoelectronic properties. Nevertheless, its photocatalytic activity is hindered by insufficient catalytic active sites and severe charge recombination. In this work, a CsPbBr 3 @Ag-C 3 N 4 ternary heterojunction photocatalyst is designed and synthesized for high-efficiency CO 2 reduction. The CsPbBr 3 quantum dots and Ag nanoparticles are chemically anchored on the surface of g-C 3 N 4 sheets, forming an electron transfer tunnel from CsPbBr 3 quantum dots to Ag nanoparticles via g-C 3 N 4 sheets. The resulting CsPbBr 3 @Ag-C 3 N 4 ternary photocatalyst, with spatial separation of photogenerated carriers, achieves a remarkable conversion rate of 19.49 μmol·g−1·h−1 with almost 100 % CO selectivity, a 3.13-fold enhancement in photocatalytic activity as compared to CsPbBr 3 quantum dots. Density functional theory calculations reveal the rapid CO 2 adsorption/activation and the decreased free energy (0.66 eV) of *COOH formation at the interface of Ag nanoparticles and g-C 3 N 4 in contrast to the g-C 3 N 4 , leading to the excellent photocatalytic activity, while the thermodynamically favored CO desorption contributes to the high CO selectivity. This work presents an innovative strategy of constructing perovskite-based photocatalyst by modulating catalyst structure and offers profound insights for efficient CO 2 conversion. [ABSTRACT FROM AUTHOR]

First-principles calculations based on spin-polarised density functional theory have been used here to investigate the structural, electronic and magnetic properties of tape-heme monolayer (THM) with gas molecules (H2O, N2, HCN, NH3, NO2 and SO2) adsorption. Our results suggest that H2O and NH3 are physisorbed on THM while N2, HCN, NO2 and SO2 are adsorbed on THM by chemisorption. The toxic HCN, NH3, NO2 and SO2 can be effectively captured by THM according to their adsorption energy (> 0.50 eV). The adsorption of NO2 (or SO2) can partly (or completely) decrease the spin moment of THM and induce the transition from the metallic property into half-metallic (or semiconductor) behaviour. The magnetism of the NO2 adsorption system is sensitive to tensile strain while that of the SO2 adsorption system is invariably non-spin polarised regardless of the compressive or tensile strain. The electronic structure of the NO2 and SO2 adsorption system can be effectively modulated by external biaxial strain. Our findings reveal that THM could effectively detect toxic NO2 and SO2 in an environment with high sensitivity and selectivity and reactivity, indicating that it possesses a potential application in the field of heme-based gas sensors. [ABSTRACT FROM AUTHOR]

In this work, we reported on the synthesis of atomically thick WSe 2 nanoribbons with straight edges and a maximum lateral size of 85 μm on SiO 2 /Si substrates via a one-step chemical vapour deposition. Optical microscope, atomic force microscope and X-ray photoelectron spectroscopy measurements were used to characterize the morphologies and chemical composition of the as-grown WSe 2 nanoribbons. Photoluminescence spectra and Raman spectra indicated that the interlayer coupling may be varied with different stacking manner. A vapour–liquid–solid mechanism was proposed to rationalize the formation of WSe 2 nanoribbons. Moreover, we showed that WSe 2 nanoribbons could also be grown on MoSe 2 flakes with the same approach, demonstrating the extendibility of this strategy. Our work provides an efficient method to obtain WSe 2 nanoribbons for novel application in catalysts and electronic devices. [Display omitted] • Epitaxial growth of atomically thick WSe 2 nanoribbons via a one-step CVD. • A 3R phase was observed at the corner of multilayer WSe 2 nanoribbons. • Epitaxial growth of WSe 2 nanoribbons on monolayer MoSe 2 substrates. • DFT calculations unravel that the edges of the WSe 2 nanoribbons are active sites. [ABSTRACT FROM AUTHOR]

As proton-exchange membrane fuel cell technology has grown and developed, there has been increasing demand for the design of novel catalyst architectures to achieve high power density and realize wide commercialization. Herein, based on the two-dimensional biphenylene, we compare the oxygen reduction reaction (ORR) activity on the active sites with different biaxial lattice strains using first-principles calculations. The ORR free energy diagrams of biphenylene monolayers with varying lattice strains suggest that the biaxial tensile strains are unfavorable for catalytic activity. In contrast, the biaxial compressive strains could improve the catalytic performance. The biphenylene systems with the strain of −2% ∼ −6% (S -0.02∼-0.06) display overpotentials of 0.37–0.49 V. This performance is comparable to or better than the Pt (111) surface. The Bader charge transfer of adsorbed O species on various biaxial strain biphenylene catalysts could be a describer to examine the catalytic activity. The catalysts possessed the moderate transferred charge of O adsorbed species often promotes catalytic process and give the high catalysis efficiency. Overall, this work suggests that the lattice strain strategy can significantly enhance the catalytic activity of biphenylene materials and further provide guidance to design biphenylene-based catalysts in various chemical reactions. [Display omitted] • Lattice strains in 2D biphenylene could enhance ORR activity. • Compressive strains of −2% ∼ −6% endow their overpotentials of 0.37–0.49 V. • Charge transfer of adsorbed O species is a descriptor to examine ORR performance. • Moderate strains and moderate transferred charge lead to excellent efficiency. [ABSTRACT FROM AUTHOR]

Background. Coronary artery ectasia (CAE) is an easily recognized abnormality of coronary artery anatomy and morphology. However, its pathogenesis remains unclear. Objectives. This study aimed to identify abnormal methylation-modified genes in patients with CAE, which could provide a research basis for CAE. Methods. Peripheral venous blood samples from patients with CAE were collected for RNA sequencing to identify differentially expressed genes (DEGs), followed by functional enrichment. Then, the DNA methylation profile of CAE was downloaded from GSE87016 (HumanMethylation450 BeadChip data, involving 11 cases and 12 normal controls) to identify differentially methylated genes (DMGs). Finally, after taking interaction genes between DEGs and DMGs, abnormal methylation-modified genes were identified, followed by protein–protein interaction analysis and expression validation using reverse transcriptase polymerase chain reaction. Results. A total of 152 DEGs and 4318 DMGs were obtained from RNA sequencing and the GSE87016 dataset, respectively. After taking interaction genes, 9 down-regulated DEGs due to hypermethylation and 11 up-regulated DEGs due to hypomethylation were identified in CAE. A total of 10 core abnormal methylation-modified genes were identified, including six down-regulated DEGs due to hypermethylation (netrin G1, ADAM metallopeptidase domain 12, immunoglobulin superfamily member 10, sarcoglycan dela, Dickkopf WNT signaling pathway inhibitor 3, and GATA binding protein 6), and four up-regulated DEGs due to hypomethylation (adrenomedullin, ubiquitin specific peptidase 18, lymphocyte antigen 6 family member E, and MX dynamin-like GTPase 1). Some signaling pathways were identified in patients with CAE, including cell adhesion molecule, O-glycan biosynthesis, and the renin–angiotensin system. Conclusions. Abnormal methylation-modified DEGs involved in signaling pathways may be involved in CAE development. [ABSTRACT FROM AUTHOR]

When bacterial species with the same resource preferences share the same growth environment, it is commonly believed that direct competition will arise. A large variety of competition and more general 'interaction' models have been formulated, but what is currently lacking are models that link monoculture growth kinetics and community growth under inclusion of emerging biological interactions, such as metabolite cross-feeding. In order to understand and mathematically describe the nature of potential cross-feeding interactions, we design experiments where two bacterial species Pseudomonas putida and Pseudomonas veronii grow in liquid medium either in mono- or as co-culture in a resource-limited environment. We measure population growth under single substrate competition or with double species-specific substrates (substrate 'indifference'), and starting from varying cell ratios of either species. Using experimental data as input, we first consider a mean-field model of resource-based competition, which captures well the empirically observed growth rates for monocultures, but fails to correctly predict growth rates in co-culture mixtures, in particular for skewed starting species ratios. Based on this, we extend the model by cross-feeding interactions where the consumption of substrate by one consumer produces metabolites that in turn are resources for the other consumer, thus leading to positive feedback in the species system. Two different cross-feeding options were considered, which either lead to constant metabolite cross-feeding, or to a regulated form, where metabolite utilization is activated with rates according to either a threshold or a Hill function, dependent on metabolite concentration. Both mathematical proof and experimental data indicate regulated cross-feeding to be the preferred model to constant metabolite utilization, with best co-culture growth predictions in case of high Hill coefficients, close to binary (on/off) activation states. This suggests that species use the appearing metabolite concentrations only when they are becoming high enough; possibly as a consequence of their lower energetic content than the primary substrate. Metabolite sharing was particularly relevant at unbalanced starting cell ratios, causing the minority partner to proliferate more than expected from the competitive substrate because of metabolite release from the majority partner. This effect thus likely quells immediate substrate competition and may be important in natural communities with typical very skewed relative taxa abundances and slower-growing taxa. In conclusion, the regulated bacterial interaction network correctly describes species substrate growth reactions in mixtures with few kinetic parameters that can be obtained from monoculture growth experiments. Author summary: Correctly predicting growth of communities of diverse bacterial taxa remains a challenge, because of the very different growth properties of individual members and their myriads of interactions that can influence growth. Here, we tried to improve and empirically validate mathematical models that combine theory of bacterial growth kinetics (i.e., Monod models) with mathematical definition of interaction parameters. We focused in particular on common cases of shared primary substrates (i.e., competition) and independent substrates (i.e., indifference) in an experimental system consisting of one fast-growing and one slower growing Pseudomonas species. Growth kinetic parameters derived from monoculture experiments included in a Monod-type consumer-resource model explained some 75% of biomass formation of either species in co-culture, but underestimated the observed growth improvement when either of the species started as a minority compared to the other. This suggested an important role of cross-feeding, whereby released metabolites from one of the partners are utilized by the other. Inclusion of cross-feeding feedback in the two-species Monod growth model largely explained empirical data at all species-starting ratios, in particular when cross-feeding is activated in almost binary manner as a function of metabolite concentration. Our results also indicate the importance of cross-feeding for minority taxa, which can explain their survival despite being poorly competitive. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) is the key bottleneck in the performance of fuel cells. The rational design of efficient and inexpensive ORR electrocatalysts is a common goal for the large-scale application of fuel cells. Herein, by means of density functional theory calculations, we demonstrate that two-dimensional (2D) biphenylene (BPN) with doping B/N are metal-free single-atom catalyst candidates with the overpotentials comparable to those noble metal benchmark catalysts. The B/N doping effectively modulates the charge distribution in BPN sheets, promotes the electron transfer between doped BPN and the oxygen-containing intermediates, which results in enhancing their binding strength, and facilitating their electrochemical ORR catalytic activity. This work not only provides metal-free single-atom catalysts for ORR, but also promotes BPN nanomaterials for single-atom catalysts development and practical applications. [Display omitted] • 2D biphenylene with doping B/N are metal-free single-atom catalysts. • N 2 -BPN exhibits superior ORR performance with a overpotential of 0.40 V. • N substituting C 2 atom in BPN could tune charge redistribution of active C 1 atom. • N 2 -BPN exhibits a suitable adsorption free energy and shows high ORR activity. [ABSTRACT FROM AUTHOR]

• The single and double Mo anchor in biphenylene monolayer exhibit good electrical conductivity. • The exposed Mo sites in Mo 1-2 @BPN possessed positive charge could capture and activate N 2 molecules. • Electrochemical nitrogen reduction reaction on precise number of Mo atoms is systematically investigated. • Mo 1 @BPN displays a limiting potential of 0.44-0.46 V, Mo 2 @BPN exhibits a low limiting potential of 0.66 V. Electrochemical nitrogen reduction (eNRR) in ambient conditions shows intriguing prospects for ammonia generation via a simple and sustainable method. By using density functional theory studies, herein we design the precise number of Mo atoms anchored biphenylene systems. Their structures, stability, chemisorption and activation of N 2 molecules are systematically investigated. We find that the single and double Mo could stably anchor in biphenylene monolayer (Mo 1-2 @BPN). The exposed Mo sites possessed positive charge could capture and activate N 2 molecules, and promote to absorb NRR intermediates. Moreover, by controlling the number of Mo atoms, the catalytic mechanisms can be significantly adjusted. The Mo 1 @BPN monolayer prefers to the distal pathway, while Mo 2 @BPN sheet tends to the enzymatic pathway. Their corresponding low limiting potentials are 0.44 V and 0.66 V, respectively, which outperform many reported catalysts to date. These studies provide a new approach for designing highly efficient NRR electrocatalysts through precise modulation number of anchored atoms. [Display omitted] [ABSTRACT FROM AUTHOR]