Gender differences in the relationship between serum uric acid and the long-term prognosis in heart failure: a nationwide study.

BACKGROUND: Serum uric acid (SUA) is an important pathogenetic and prognostic factor for heart failure (HF). Gender differences are apparent in HF. Furthermore, gender differences also exist in the association between SUA and prognosis in various cardiovascular diseases. However, the gender difference for SUA in the prediction of long-term prognosis in HF is still ambiguous. METHODS: A total of 1593 HF patients (897 men, 696 women) from the National Health and Nutrition Examination Survey (NHANES) 1999-2018 cycle were enrolled in our final analysis. Participants were categorized according to gender-specific SUA tertile. We assessed the association between SUA and long-term prognosis of HF patients, defined as all-cause mortality and cardiovascular mortality, in different genders via Kaplan-Meier curve analysis, Cox proportional hazard model, and Fine-Gray competing risk model. The restricted cubic spline (RCS) was performed to investigate the dose-response relationship between SUA and outcomes. RESULTS: Gender differences exist in demographic characteristics, clinical parameters, laboratory tests, and medication of HF patients. After a median follow-up of 127 months (95% CI 120-134 months), there were 853 all-cause deaths (493 events in men, 360 events in women) and 361 cardiovascular deaths (206 events in men, 155 events in women). Kaplan-Meier analysis showed that SUA had gender difference in the prediction of cardiovascular mortality (Log-rank p < 0.001, for male, Log-rank p = 0.150, for female), but not in all-cause mortality. Multivariate Cox regression analysis revealed that elevated SUA levels were associated with higher all-cause mortality and cardiovascular mortality in men (HR 1.11, 95% CI 1.05-1.18, p < 0.001, for all-cause death; HR 1.18, 95% CI 1.09-1.28, p < 0.001, for cardiovascular death), but not in women (HR 1.05, 95% CI 0.98-1.12, p = 0.186, for all-cause death; HR 1.01, 95% CI 0.91-1.12, p = 0.902, for cardiovascular death). Even using non-cardiovascular death as a competitive risk, adjusted Fine-Gray model also illustrated that SUA was an independent predictor of cardiovascular death in men (SHR 1.17, 95% CI 1.08-1.27, p < 0.001), but not in women (SHR 0.98, 95% CI 0.87 - 1.10, p = 0.690). CONCLUSIONS: Gender differences in the association between SUA and long-term prognosis of HF existed. SUA was an independent prognostic predictor for long-term outcomes of HF in men, but not in women.

Influence of Failure-Load Prediction in Composite Single-Lap Joints with Brittle and Ductile Adhesives Using Different Progressive-Damage Techniques.

The usage of adhesively bonded joints, such as single-lap and double-lap joints, is increasing rapidly in aerospace composite structures as a popular alternative to bolts and rivets. Compared to the conventional joining methods such as fastening and riveting, adhesive-bonding technology better prevents damage to composite structures due to the smooth configuration and the mitigation of stress concentration around holes. In this work, the built-in progressive-damage-modeling techniques in Abaqus, including the cohesive zone model (CZM) and the virtual crack closure technique (VCCT), are used to predict the strength and progressive failure of composite single-lap joints subjected to tensile loading. Modeling of an adhesive layer by using a zero/non-zero-thickness cohesive element, cohesive surface, and VCCT is investigated, as is the effect of brittle and ductile adhesives. Two-dimensional finite-element models with different damage-modeling strategies are performed in this study. The failure-load predictions are compared with the experimental results obtained from the literature. For the ductile adhesive, the predicted failure loads using a zero/non-zero-thickness cohesive elements and a cohesive surface are all shown to be in good agreement with the experiments. However, the VCCT technique predicts higher failure loads. For a brittle adhesive, on the other hand, the predictions by zero/non-zero-thickness cohesive elements and cohesive surfaces reveal notable deviations compared to the experimental results. In contrast to the ductile adhesive, the VCCT technique is revealed to be accurate in predicting the brittle adhesive.

Transcriptomic analysis reveals the potential crosstalk genes and immune relationship between Crohn's disease and atrial fibrillation.

Background: At present, there is a paucity of research on the link between Crohn's disease (CD) and atrial fibrillation (AF). Nevertheless, both ailments are thought to entail inflammatory and autoimmune processes, and emerging evidence indicates that individuals with CD may face an elevated risk of AF. To shed light on this issue, our study seeks to explore the possibility of shared genes, pathways, and immune cells between these two conditions. Methods: We retrieved the gene expression profiles of both CD and AF from the Gene Expression Omnibus (GEO) database and subjected them to analysis. Afterward, we utilized the weighted gene co-expression network analysis (WGCNA) to identify shared genes, which were then subjected to further Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Furthermore, we employed a rigorous analytical approach by screening hub genes through both least absolute shrinkage and selection operator (LASSO) regression and support vector machine (SVM), and subsequently constructing a receiver operating characteristic (ROC) curve based on the screening outcomes. Finally, we utilized single-sample gene set enrichment analysis (ssGSEA) to comprehensively evaluate the levels of infiltration of 28 immune cells within the expression profile and their potential association with the shared hub genes. Results: Using the WGCNA method, we identified 30 genes that appear to be involved in the pathological progression of both AF and CD. Through GO enrichment analysis on the key gene modules derived from WGCNA, we observed a significant enrichment of pathways related to major histocompatibility complex (MHC) and antigen processing. By leveraging the intersection of LASSO and SVM algorithms, we were able to pinpoint two overlapping genes, namely CXCL16 and HLA-DPB1. Additionally, we evaluated the infiltration of immune cells and observed the upregulation of CD4+ and CD8+ T cells, as well as dendritic cells in patients with AF and CD. Conclusions: By employing bioinformatics tools, we conducted an investigation with the objective of elucidating the genetic foundations that connect AF and CD. This study culminated in the identification of CXCL16 and HLA-DPB1 as the most substantial genes implicated in the development of both disorders. Our findings suggest that the immune responses mediated by CD4+ and CD8+ T cells, along with dendritic cells, may hold a crucial role in the intricate interplay between AF and CD.

The study of DIEA three dimensional reconstruction technique based on CTA in preoperative perforator selection.

Preoperative selection of perforator is one of the key steps for successful surgery. The purpose of this study is to simulate the selection process of the perforator of the flap using the 3D models of the deep inferior epigastric artery (DIEA). A retrospective study was performed of women who underwent deep inferior epigastric perforator flap breast reconstruction from January 2011 to July 2021. Construct 3D models of the DIEA using computerized tomography angiography images, and then computational fluid dynamics simulations were performed. Correlation and regression analyses were used to analyze the geometric and hemodynamic parameters. Statistical analysis suggested that the outlet flow was positively correlated with the inlet area (r = 0.338, p = 0.000), outlet area (r = 0.840, p = 0.000), the average radius of the perforator (r = 0.592, p = 0.000), and negatively correlated with the length of perforator(r = -0.210, p = 0.024). The results of linear regression analysis showed that the outlet area (p = 0.000), the average radius (p = 0.000), and the length (p = 0.044) of the perforator were the influencing factors on outlet flow. In multiple perforators analysis, there was a significant difference in the total outlet flow among single perforator, double perforators, and triple perforators (p = 0.002). The successful implementation of this experiment provides a new approach for the selection of dominant perforators in the future.

Construction of a Quantum-Dot-Based FRET Nanosensor through Direct Encoding of Streptavidin-Binding RNA Aptamers for N6-Methyladenosine Demethylase Detection.

N6-Methyladenosine (m6A) demethylases can catalyze the removal of the methyl modification on m6A, and it is closely associated with the occurrence, proliferation, differentiation, and metastasis of malignancies. The m6A demethylases (e.g., fat mass and obesity-associated protein (FTO)) may act as a cancer biomarker and are crucial for anticancer drug screening and early clinical diagnosis. Herein, we demonstrate the construction of a quantum-dot-based Förster resonance energy-transfer (FRET) nanosensor through direct encoding of streptavidin-binding RNA aptamers (SA aptamers) for m6A demethylase detection. This nanosensor employs multiple Cy5-molecule-labeled SA aptamers as the building materials to construct the 605QD-RNA-Cy5 nanoassembly, and it exploits the hinder effect of m6A upon elongation and ligation reactions to distinguish m6A-containing RNA probes from demethylated RNA probes. When m6A demethylase is present, the m6A-containing RNA probes are demethylated to generate the demethylated RNA probes, initiating strand extension and ligation reactions to yield a complete transcription template for SA aptamers. Subsequently, a T7-assisted cascade transcription amplification reaction is activated to transcribe abundant SA aptamers with the incorporation of multiple Cy5 fluorophores. The Cy5-incorporated SA aptamers can self-assembly onto the streptavidin-coated 605QD surface to obtain the 605QD-SA aptamer-Cy5 nanoassemblies, resulting in the generation of distinct FRET signals. This nanosensor exhibits ultrahigh sensitivity and excellent specificity, and it can detect endogenous FTO at the single-cell level. Furthermore, this nanosensor can precisely measure enzyme kinetic parameters, screen m6A demethylase inhibitors, and differentiate the FTO expression between breast cancer patients and healthy individual tissues, offering a versatile platform for clinical diagnostic and drug discovery.

Imaging the electron charge density in monolayer MoS2 at the Ångstrom scale.

Four-dimensional scanning transmission electron microscopy (4D-STEM) has recently gained widespread attention for its ability to image atomic electric fields with sub-Ångstrom spatial resolution. These electric field maps represent the integrated effect of the nucleus, core electrons and valence electrons, and separating their contributions is non-trivial. In this paper, we utilized simultaneously acquired 4D-STEM center of mass (CoM) images and annular dark field (ADF) images to determine the projected electron charge density in monolayer MoS2. We evaluate the contributions of both the core electrons and the valence electrons to the derived electron charge density; however, due to blurring by the probe shape, the valence electron contribution forms a nearly featureless background while most of the spatial modulation comes from the core electrons. Our findings highlight the importance of probe shape in interpreting charge densities derived from 4D-STEM and the need for smaller electron probes.

[Composition Characteristics of Volatile Organic Compounds and Associated Contributions to Secondary Pollution in Shenyang Industrial Area in Summer].

Based on the observation data of volatile organic compounds (VOCs) in the industrial area of Shenyang during the summer of 2019 and 2020, the composition characteristics and sources of VOCs were preliminarily studied. The ozone formation potential (OFP) and aerosol formation potential (AFP) of VOCs were also estimated using the max incremental reactivity (MIR) and aerosol formation coefficient (FAC) methods, respectively. The results showed that the average concentration of VOCs was 41.66 µg·m-3, and the proportions of alkanes, olefins, aromatics, and acetylene were 48.50%, 14.08%, 15.37%, and 22.05%, respectively. The top ten species of VOCs were primarily C2-C5 alkanes, also including acetylene, ethylene, and some aromatics, accounting for 69.25% of the total VOCs. VOCs showed obvious diurnal variation characteristics with a high concentration in the morning and evening (at 06:00 and 22:00) and a low concentration in the afternoon (11:00-16:00). According to the value of toluene/benzene (T/B) and isopentane/n-pentane, the atmosphere of the industrial area was mainly affected by vehicle exhaust emissions, solvent use, combustion sources, and LPG/NG. The total AFP of VOCs was up to 41.43×10-2 µg·m-3, and aromatics were the largest contributor. The total OFP of VOCs reached 117.59 µg·m-3, in which the alkenes contributed the most.

Evolution of nanopores in hexagonal boron nitride.

The engineering of atomically-precise nanopores in two-dimensional materials presents exciting opportunities for both fundamental science studies as well as applications in energy, DNA sequencing, and quantum information technologies. The exceptional chemical and thermal stability of hexagonal boron nitride (h-BN) suggest that exposed h-BN nanopores will retain their atomic structure even when subjected to extended periods of time in gas or liquid environments. Here we employ transmission electron microscopy to examine the time evolution of h-BN nanopores in vacuum and in air and find, even at room temperature, dramatic geometry changes due to atom motion and edge contamination adsorption, for timescales ranging from one hour to one week. The discovery of nanopore evolution contrasts with general expectations and has profound implications for nanopore applications of two-dimensional materials.

Corn-Based Fluorescent Light-Up Biosensors with Improved Signal-to-Background Ratio for Label-Free Detection of Long Noncoding RNAs.

Long noncoding RNAs (lncRNAs) play pivotal roles in multifarious physiological and pathological processes, and their aberrant expression may disturb the normal regulatory network of gene expression to induce diverse human diseases. Herein, we construct a fluorescent light-up biosensor with a low background for label-free detection of lncRNAs by coupling duplex-specific nuclease (DSN)-assisted target recycling amplification with transcription-driven synthesis of fluorogenic RNA aptamer-Corns. We design two linear probes, including a capture probe for initiating a cyclic cleavage reaction and a linear template for transcribing RNA aptamer-Corn. Target lncRNA is recognized by capture probes assembled on magnetic bead (MB) surfaces to trigger a DSN-assisted cyclic cleavage reaction, releasing abundant T7 promoter sequences. After magnetic separation, free T7 promoter hybridizes with a linear template to induce efficient transcription amplification with the assistance of T7 RNA polymerase, producing numerous fluorogenic RNA aptamer-Corns that can light up small-molecule fluorogens 3,5-difluoro-4-hydroxybenzylidene-imidazolinone-2-oxime (DFHO). Notably, the introduction of MBs facilitates both the separation of cleaved capture probes and the enrichment/isolation of target lncRNAs from the complex biological matrix. Benefiting from the high efficiency of DSN/T7 RNA polymerase-mediated cascade amplification and high signal-to-background ratio of the Corn-DFHO complex, this biosensor is capable of sensitively quantifying lncRNA with a detection limit of 31.98 aM. Moreover, it can precisely quantify lncRNA at the single-cell level and even in complex biological samples, and it can differentiate tumor cells from normal cells. Importantly, this Corn-based biosensor is readily extended to detect other lncRNAs by altering capture probe sequences, opening a new avenue for molecular diagnosis.

Deep-Learning Electron Diffractive Imaging.

We report the development of deep-learning coherent electron diffractive imaging at subangstrom resolution using convolutional neural networks (CNNs) trained with only simulated data. We experimentally demonstrate this method by applying the trained CNNs to recover the phase images from electron diffraction patterns of twisted hexagonal boron nitride, monolayer graphene, and a gold nanoparticle with comparable quality to those reconstructed by a conventional ptychographic algorithm. Fourier ring correlation between the CNN and ptychographic images indicates the achievement of a resolution in the range of 0.70 and 0.55 Å. We further develop CNNs to recover the probe function from the experimental data. The ability to replace iterative algorithms with CNNs and perform real-time atomic imaging from coherent diffraction patterns is expected to find applications in the physical and biological sciences.

Tuning colour centres at a twisted hexagonal boron nitride interface.

The colour centre platform holds promise for quantum technologies, and hexagonal boron nitride has attracted attention due to the high brightness and stability, optically addressable spin states and wide wavelength coverage discovered in its emitters. However, its application is hindered by the typically random defect distribution and complex mesoscopic environment. Here, employing cathodoluminescence, we demonstrate on-demand activation and control of colour centre emission at the twisted interface of two hexagonal boron nitride flakes. Further, we show that colour centre emission brightness can be enhanced by two orders of magnitude by tuning the twist angle. Additionally, by applying an external voltage, nearly 100% brightness modulation is achieved. Our ab initio GW and GW plus Bethe-Salpeter equation calculations suggest that the emission is correlated to nitrogen vacancies and that a twist-induced moiré potential facilitates electron-hole recombination. This mechanism is further exploited to draw nanoscale colour centre patterns using electron beams.

MnO2 nanosheet-mediated generalist probe: Cancer-targeted dual-microRNAs detection and enhanced CDT/PDT synergistic therapy.

While integrated nanoplatform for diagnosis and therapy has received much recent interest, its widespread application has been hampered by the complicated preparation process, high-cost and low-efficacy. Herein, we designed a MnO2 nanosheet-mediated generalist probe (MNSGP), for intracellular dual-microRNAs (miRNAs) imaging and enhanced synergistic therapy of chemodynamic therapy (CDT) and photodynamic therapy (PDT). Because MNSGP can specifically target nucleolin receptor overexpressed on the cancer cell surface, it can be internalized via a receptor-mediated endocytosis pathway. After entering the cells, MnO2 NS was degraded to Mn2+ by the excessive glutathione (GSH), releasing the DNA probes for cyclic amplification detection of miR-155 and miR-21 based on toehold-mediated strand displacement amplification (TSDA). Meanwhile, the produced O2 by MnO2 NS catalysis can promote the photosensitizer TMPyP4 to produce singlet oxygen (1O2) for PDT. The degraded Mn2+, as Fenton reagent, can convert endogenous H2O2 to cytotoxic hydroxyl radical (·OH) for CDT. In addition, the depletion of GSH impairs the antioxidant defense system (ADS), enhancing the CDT/PDT synergistic effect. The prepared generalist probe was fully characterized. Accuracy of dual-miRNAs detection and the high curative effect of enhanced CDT/PDT synergistic therapy were attested via in vitro and in vivo experiments. Unarguably, MNSGP broadens new horizons in the design of nucleic acid nanoplatform, cancer-targeted detection and theranostic application.

Beam-driven Dynamics of Aluminium Dopants in Graphene.

Substituting heteroatoms into graphene can tune its properties for applications ranging from catalysis to spintronics. The further recent discovery that covalent impurities in graphene can be manipulated at atomic precision using a focused electron beam may open avenues towards sub-nanometer device architectures. However, the preparation of clean samples with a high density of dopants is still very challenging. Here, we report vacancy-mediated substitution of aluminium into laser-cleaned graphene, and without removal from our ultra-high vacuum apparatus, study their dynamics under 60 keV electron irradiation using aberration-corrected scanning transmission electron microscopy and spectroscopy. Three- and four-coordinated Al sites are identified, showing excellent agreement with ab initio predictions including binding energies and electron energy-loss spectrum simulations. We show that the direct exchange of carbon and aluminium atoms predicted earlier occurs under electron irradiation, although unexpectedly it is less probable than the same process for silicon. We also observe a previously unknown nitrogen-aluminium exchange that occurs at Al─N double-dopant sites at graphene divacancies created by our plasma treatment.

Accelerated Ultrafast Magnetization Dynamics at Graphene/CoGd Interfaces.

Atomically thin graphene layers can act as a spin-sink material when adjacent to a nanoscale magnetic surface. The enhancement in the extrinsic spin-orbit coupling (SOC) strength of graphene plays an important role in absorbing the spin angular momentum injected from the magnetic surface after perturbation with an external stimulus. As a result, the dynamics of the excited spin system is modified within the magnetic layer. In this paper, we demonstrate the modulation of ultrafast magnetization dynamics at graphene/ferrimagnet interfaces using the time-resolved magneto-optical Kerr effect (TRMOKE) technique. Magnetically modified interfaces with a systematic increase in the number of graphene layers coupled with the 10 nm-thick Co74Gd26 layer are studied. We find that the variation in the dynamical parameters, i.e., ultrafast demagnetization time, remagnetization times, decay time, effective damping, precessional frequency, etc., observed at different time scales is interconnected. The demagnetization time and decay time for the ferrimagnet become approximately two times faster than the corresponding intrinsic values. We found a possible correlation between the demagnetization time and damping. The effect is more pronounced for the interfaces with monolayer graphene and graphite. The spin-mixing conductance is found to be approximately 0.8 × 1015 cm-2. The effect of SOC, pure spin current, the appearance of structural defects, and thermal properties at the graphene/ferrimagnet interface are responsible for the modifications of several dynamical parameters. This work demonstrates some important properties of the graphene/ferrimagnet interface which may unravel the possibilities of designing spintronic devices with elevated performance in the future.

High Prevalence of Klebsiella pneumoniae Infections in AnHui Province: Clinical Characteristic and Antimicrobial Resistance.

BACKGROUND: Klebsiella pneumoniae (K. pneumoniae) causes community-acquired and hospital-acquired pneumonia. The mortality rates of invasive infections caused by hypervirulent K. pneumoniae (HvKP) are extremely high. However, the microbiological characteristics and clinical manifestations of K. pneumoniae in AnHui province still remain unclear. PURPOSE: To show the high prevalence of HvKP infections regarding clinical characteristics and antimicrobial resistance in Anhui province. PATIENTS AND METHODS: A retrospective analysis was conducted to study the clinical data of 115 strains of K. pneumoniae from July 2019 to March 2020 in The First Affiliated Hospital of AnHui Medical University. The virulence genes, capsular types, carbapenemase genes, and molecular subtypes of these hypervirulent isolates were detected. RESULTS: Overall, 59.1% (68/115) cases were HvKP infections, mainly from the department of intensive care unit (ICU, n=14, 20.6%) and the department of respiratory and critical care (n=13, 19.1%). K2 was the most prevalent capsular serotype (n=26), followed by K1 (n=21). The results of MLST identification of 68 strains showed that ST23 (n=15, 22.1%) was the most common type of ST, followed by ST11 and ST65 (n=12, 17.6%), ST86 (n=9, 13.2%), and ST412 (n=6, 8.8%). Among 68 hvKP strains, 12 isolates were carbapenem resistant, and all except two harboured KPC. CONCLUSION: The high incidence of carbapenemase producing HvKP in the Anhui province, especially the higher mortality of HvKP, should be paid more attention. Meanwhile, epidemiological surveillance and clinical treatment strategies should be continuously determined and implemented.

Revealing the Brønsted-Evans-Polanyi relation in halide-activated fast MoS2 growth toward millimeter-sized 2D crystals.

Achieving large-size two-dimensional (2D) crystals is key to fully exploiting their remarkable functionalities and application potentials. Chemical vapor deposition growth of 2D semiconductors such as monolayer MoS2 has been reported to be activated by halide salts, for which various investigations have been conducted to understand the underlying mechanism from different aspects. Here, we provide experimental evidence showing that the MoS2 growth dynamics are halogen dependent through the Brønsted-Evans-Polanyi relation, based on which we build a growth model by considering MoS2 edge passivation by halogens, and theoretically reproduce the trend of our experimental observations. These mechanistic understandings enable us to further optimize the fast growth of MoS2 and reach record-large domain sizes that should facilitate practical applications.

Antioxidative and immunological effects of Cyclocarya paliurus polysaccharides on the spleen injury of diabetic rat.

OBJEVTIVE: To investigate the effects of Cyclocarya paliurus (C. paliurus) polysaccharides on the spleen injury of diabetic rats. METHODS: Animals were divided into 6 groups, including normal group, model group, control group, low-dose group of C. paliurus polysaccharides treatment, middle-dose group of C. paliurus polysaccharides treatment and high-dose group of C. paliurus polysaccharides treatment. Histological analysis of spleen was analyzed using hematoxilin and eosin. Levels of biological parameters and anti-oxidative enzymes were determined by spectrophotometry. Interleukin-7 (IL-7) and IL-10 were measured by enzyme-linked immunosorbent assay. RESULTS: Compared with that of model group, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase level increased 78.63% (P < 0.05), 51.76% (P < 0.05), 2.95 times (P < 0.01) and 41.11% (P < 0.05) in the high-dose group of C. paliurus polysaccharides treatment, respectively. IL-7 and IL-10 increase 1.66 (P < 0.01) and 1.21 times (P < 0.01) in the high-dose group of C. paliurus polysaccharides treatment, respectively. CONCLUSION: It is suggested that C. paliurus polysaccharides may play a protecting role for spleen injury of diabetic rats by enhancing the antioxidative ability and evaluating the immunity.

[Pollution Characteristics and Ozone Formation Potential of Ambient VOCs in Different Functional Zones of Shenyang, China].

Ambient volatile organic compounds(VOCs) were determined by GC 5000 online gas chromatography in three functional areas of Shenyang, namely industrial, traffic, and mixed cultural and educational areas. The pollution characteristics of VOCs in these functional areas during the heating and non-heating periods were analyzed, and the ozone formation potential(OFP) was estimated by using maximum incremental reactivity(MIR). The results show that the average mass concentration of VOCs is(82.19±54.99) µg·m-3 in Shenyang, of which the concentration in industrial areas is significantly higher than that in traffic and cultural and educational mixed areas, and the heating period is higher. The traffic and mixed cultural and educational areas have bi-modal characteristics due to the morning and evening traffic, and the industrial area has multiple peaks affected by the irregular operation hours. The proportion of VOCs in traffic and mixed cultural and educational areas shows the order of alkanes>aromatic hydrocarbons>alkenes>alkynes, but the proportion of alkynes in industrial areas is higher than that of alkenes. The benzene to toluene(B/T) and ethane to acetylene(E/A) ratios reflects that traffic and mixed cultural and educational areas were affected by both vehicle exhaust emissions and fuel combustion. The industrial zone is therefore affected by complex sources, and there are more aged air masses during the heating period than non-heating period. The average OFP contribution of atmospheric VOCs in Shenyang is 232.89 µg·m-3. The contribution of alkenes is largest for all functional areas, and the aromatic component also contributes more due to the high concentration of industrial areas.

Designing artificial two-dimensional landscapes via atomic-layer substitution.

Technology advancements in history have often been propelled by material innovations. In recent years, two-dimensional (2D) materials have attracted substantial interest as an ideal platform to construct atomic-level material architectures. In this work, we design a reaction pathway steered in a very different energy landscape, in contrast to typical thermal chemical vapor deposition method in high temperature, to enable room-temperature atomic-layer substitution (RT-ALS). First-principle calculations elucidate how the RT-ALS process is overall exothermic in energy and only has a small reaction barrier, facilitating the reaction to occur at room temperature. As a result, a variety of Janus monolayer transition metal dichalcogenides with vertical dipole could be universally realized. In particular, the RT-ALS strategy can be combined with lithography and flip-transfer to enable programmable in-plane multiheterostructures with different out-of-plane crystal symmetry and electric polarization. Various characterizations have confirmed the fidelity of the precise single atomic layer conversion. Our approach for designing an artificial 2D landscape at selective locations of a single layer of atoms can lead to unique electronic, photonic, and mechanical properties previously not found in nature. This opens a new paradigm for future material design, enabling structures and properties for unexplored territories.