Collapse of carbon nanotubes due to local high-pressure from van der Waals encapsulation.

Van der Waals (vdW) assembly of low-dimensional materials has proven the capability of creating structures with on-demand properties. It is predicted that the vdW encapsulation can induce a local high-pressure of a few GPa, which will strongly modify the structure and property of trapped materials. Here, we report on the structural collapse of carbon nanotubes (CNTs) induced by the vdW encapsulation. By simply covering CNTs with a hexagonal boron nitride flake, most of the CNTs (≈77%) convert from a tubular structure to a collapsed flat structure. Regardless of their original diameters, all the collapsed CNTs exhibit a uniform height of ≈0.7 nm, which is roughly the thickness of bilayer graphene. Such structural collapse is further confirmed by Raman spectroscopy, which shows a prominent broadening and blue shift in the Raman G-peak. The vdW encapsulation-induced collapse of CNTs is fully captured by molecular dynamics simulations of the local vdW pressure. Further near-field optical characterization reveals a metal-semiconductor transition in accompany with the CNT structural collapse. Our study provides not only a convenient approach to generate local high-pressure for fundamental research, but also a collapsed-CNT semiconductor for nanoelectronic applications.

Observation of a Chern insulator in crystalline ABCA-tetralayer graphene with spin-orbit coupling.

Degeneracies in multilayer graphene, including spin, valley, and layer degrees of freedom, can be lifted by Coulomb interactions, resulting in rich broken-symmetry states. Here, we report a ferromagnetic state in charge-neutral ABCA-tetralayer graphene driven by proximity-induced spin-orbit coupling from adjacent tungsten diselenide. The ferromagnetic state is identified as a Chern insulator with a Chern number of 4; its maximum Hall resistance reaches 78% quantization at zero magnetic field and is fully quantized at either 0.4 or -1.5 tesla. Three distinct broken-symmetry insulating states, layer-antiferromagnet, Chern insulator, and layer-polarized insulator, along with their transitions, can be continuously tuned by the vertical displacement field. In this system, the magnetic order of the Chern insulator can be switched by three knobs, including magnetic field, electrical doping, and vertical displacement field.

Graphene nanoribbons grown in hBN stacks for high-performance electronics.

Van der Waals encapsulation of two-dimensional materials in hexagonal boron nitride (hBN) stacks is a promising way to create ultrahigh-performance electronic devices1-4. However, contemporary approaches for achieving van der Waals encapsulation, which involve artificial layer stacking using mechanical transfer techniques, are difficult to control, prone to contamination and unscalable. Here we report the transfer-free direct growth of high-quality graphene nanoribbons (GNRs) in hBN stacks. The as-grown embedded GNRs exhibit highly desirable features being ultralong (up to 0.25 mm), ultranarrow (<5 nm) and homochiral with zigzag edges. Our atomistic simulations show that the mechanism underlying the embedded growth involves ultralow GNR friction when sliding between AA'-stacked hBN layers. Using the grown structures, we demonstrate the transfer-free fabrication of embedded GNR field-effect devices that exhibit excellent performance at room temperature with mobilities of up to 4,600 cm2 V-1 s-1 and on-off ratios of up to 106. This paves the way for the bottom-up fabrication of high-performance electronic devices based on embedded layered materials.

Scalable Synthesis of High-Quality Ultrathin Ferroelectric Magnesium Molybdenum Oxide.

The development of ultrathin, stable ferroelectric materials is crucial for advancing high-density, low-power electronic devices. Nonetheless, ultrathin ferroelectric materials are rare due to the critical size effect. Here, a novel ferroelectric material, magnesium molybdenum oxide (Mg2 Mo3 O8 ) is presented. High-quality ultrathin Mg2 Mo3 O8 crystals are synthesized using chemical vapor deposition (CVD). Ultrathin Mg2 Mo3 O8 has a wide bandgap (≈4.4 eV) and nonlinear optical response. Mg2 Mo3 O8 crystals of varying thicknesses exhibit out-of-plane ferroelectric properties at room temperature, with ferroelectricity retained even at a 2 nm thickness. The Mg2 Mo3 O8 exhibits a relatively large remanent polarization ranging from 33 to 52 µC cm- 2 , which is tunable by changing its thickness. Notably, Mg2 Mo3 O8 possesses a high Curie temperature (>980 °C) across various thicknesses. Moreover, the as-grown Mg2 Mo3 O8 crystals display remarkable stability under harsh environments. This work introduces nolanites-type crystal into ultrathin ferroelectrics. The scalable synthesis of stable ultrathin ferroelectric Mg2 Mo3 O8 expands the scope of ferroelectric materials and may prosper applications of ferroelectrics.

Electron/infrared-phonon coupling in ABC trilayer graphene.

Stacking order plays a crucial role in determining the crystal symmetry and has significant impacts on electronic, optical, magnetic, and topological properties. Electron-phonon coupling, which is central to a wide range of intriguing quantum phenomena, is expected to be intricately connected with stacking order. Understanding the stacking order-dependent electron-phonon coupling is essential for understanding peculiar physical phenomena associated with electron-phonon coupling, such as superconductivity and charge density waves. In this study, we investigate the effect of stacking order on electron-infrared phonon coupling in graphene trilayers. By using gate-tunable Raman spectroscopy and excitation frequency-dependent near-field infrared nanoscopy, we show that rhombohedral ABC-stacked trilayer graphene has a significant electron-infrared phonon coupling strength. Our findings provide novel insights into the superconductivity and other fundamental physical properties of rhombohedral ABC-stacked trilayer graphene, and can enable nondestructive and high-throughput imaging of trilayer graphene stacking order using Raman scattering.

Atomically precise photothermal nanomachines.

Interfacing molecular machines to inorganic nanoparticles can, in principle, lead to hybrid nanomachines with extended functions. Here we demonstrate a ligand engineering approach to develop atomically precise hybrid nanomachines by interfacing gold nanoclusters with tetraphenylethylene molecular rotors. When gold nanoclusters are irradiated with near-infrared light, the rotation of surface-decorated tetraphenylethylene moieties actively dissipates the absorbed energy to sustain the photothermal nanomachine with an intact structure and steady efficiency. Solid-state nuclear magnetic resonance and femtosecond transient absorption spectroscopy reveal that the photogenerated hot electrons are rapidly cooled down within picoseconds via electron-phonon coupling in the nanomachine. We find that the nanomachine remains structurally and functionally intact in mammalian cells and in vivo. A single dose of near-infrared irradiation can effectively ablate tumours without recurrence in tumour-bearing mice, which shows promise in the development of nanomachine-based theranostics.

Spontaneous broken-symmetry insulator and metals in tetralayer rhombohedral graphene.

Interactions among charge carriers in graphene can lead to the spontaneous breaking of multiple degeneracies. When increasing the number of graphene layers following rhombohedral stacking, the dominant role of Coulomb interactions becomes pronounced due to the significant reduction in kinetic energy. In this study, we employ phonon-polariton-assisted near-field infrared imaging to determine the stacking orders of tetralayer graphene devices. Through quantum transport measurements, we observe a range of spontaneous broken-symmetry states and their transitions, which can be finely tuned by carrier density n and electric displacement field D. Specifically, we observe a layer-antiferromagnetic insulator at n = D = 0 with a gap of approximately 15 meV. Increasing D allows for a continuous phase transition from a layer-antiferromagnetic insulator to a layer-polarized insulator. By simultaneously tuning n and D, we observe isospin-polarized metals, including spin-valley-polarized and spin-polarized metals. These transitions are associated with changes in the Fermi surface topology and are consistent with the Stoner criteria. Our findings highlight the efficient fabrication of specially stacked multilayer graphene devices and demonstrate that crystalline multilayer graphene is an ideal platform for investigating a wide range of broken symmetries driven by Coulomb interactions.

Information quality of videos related to Helicobacter pylori infection on TikTok: Cross-sectional study.

BACKGROUND: Helicobacter pylori (H. pylori) poses serious threats to human health. TikTok (Douyin in Chinese), a major social media platform focused on sharing short videos, has demonstrated great potential in spreading health information, including information related to H. pylori infection. This study aims to evaluate the content and quality of the information shared in TikTok videos about H. pylori infection in mainland China. METHODS: We collected a sample of 116 videos in Chinese related to H. pylori infection from TikTok. Video contents were evaluated by the coding schema proposed by Goobie et al., and the Hexagonal Radar Schema was used to intuitively display the spotlight and weight of each aspect of the videos. The DISCERN questionnaire was used to evaluate the quality of the videos. RESULTS: We identified two major sources of videos related to H. pylori: individual users (n = 89) and organizational users (n = 27). Regarding content, the Hexagonal Radar Charts showed that more than 35% of the videos delivered moderate to high quality content (>1 point) in terms of definition, symptoms and management of the disease, whereas risk factors, evaluation and outcomes of the disease were less discussed. The DISCERN classification data showed that 0.9% of the videos were "very poor," 5.2% "poor," 68.7% "fair," 20.0% "good," and only 5.2% "excellent". Regarding total DISCERN scores, videos published by nonprofit organizations had the highest scores, followed by videos uploaded by health professionals. CONCLUSION: Although the overall quality of TikTok videos related to H. pylori infection was medium, users should be careful when obtaining information related to H. pylori infection on TikTok and opt for videos uploaded by nonprofit organizations and health professionals.

Tip Growth of Quasi-Metallic Bilayer Graphene Nanoribbons with Armchair Chirality.

Graphene nanoribbons (GNRs), quasi one-dimensional (1D) narrow strips of graphene, have shown promise for high-performance nanoelectronics due to their exceptionally high carrier mobility and structurally tunable bandgaps. However, producing chirality-uniform GNRs on insulating substrates remains a big challenge. Here, we report the successful growth of bilayer GNRs with predominantly armchair chirality and ultranarrow widths (<5 nm) on insulating hexagonal boron nitride (h-BN) substrates using chemical vapor deposition (CVD). The growth of GNRs is catalyzed by transition metal nanoparticles, including Fe, Co, and Ni, through a unique tip-growth mechanism. Notably, GNRs catalyzed by Ni exhibit a high purity (97.3%) of armchair chirality. Electron transport measurements indicate that the ultrathin bilayer armchair GNRs exhibit quasi-metallic behavior. This quasi-metallicity is further supported by density functional theory (DFT) calculations, which reveal a significantly reduced bandgap in bilayer armchair GNRs. The chirality-specific GNRs reported here offer promising advancements for the application of graphene in nanoelectronics.

Magnetic Field-Stabilized Wigner Crystal States in a Graphene Moiré Superlattice.

ABC-stacked trilayer graphene on boron nitride (ABC-TLG/hBN) moiré superlattices provides a tunable platform for exploring Wigner crystal states in which the electron correlation can be controlled by electric and magnetic fields. Here we report the observation of magnetic field-stabilized Wigner crystal states in a ABC-TLG/hBN. We show that correlated insulating states emerge at multiple fractional and integer fillings corresponding to ν = 1/3, 2/3, 1, 4/3, 5/3, and 2 electrons per moiré lattice site under a magnetic field. These correlated insulating states can be attributed to generalized Mott states for the integer fillings and generalized Wigner crystal states for the fractional fillings. The generalized Wigner crystal states are stabilized by a vertical magnetic field and are strongest at one magnetic flux quantum per three moiré superlattices. The ν = 2 insulating state persists up to 30 T, which can be described by a Mott-Hofstadter transition at a high magnetic field.

Skeletal muscle alterations indicate poor prognosis in cirrhotic patients: a multicenter cohort study in China.

INTRODUCTION: We aimed to determine the diagnostic criteria of myosteatosis in a Chinese population and investigate the effect of skeletal muscle abnormalities on the outcomes of cirrhotic patients. METHODS: Totally 911 volunteers were recruited to determine the diagnostic criteria and impact factors of myosteatosis, and 480 cirrhotic patients were enrolled to verify the value of muscle alterations for prognosis prediction and establish new noninvasive prognostic strategies. RESULTS: Multivariate analysis showed age, sex, weight, waist circumference, and biceps circumference had a remarkable influence on the L3 skeletal muscle density (L3-SMD). Based on the cut-off of a mean - 1.28 × SD among adults aged < 60 years, the diagnostic criteria for myosteatosis was L3-SMD < 38.93 Hu in males and L3-SMD < 32.82 Hu in females. Myosteatosis rather than sarcopenia has a close correlation with portal hypertension. The concurrence of sarcopenia and myosteatosis not only is associated with poor liver function but also evidently reduced the overall and liver transplantation-free survival of cirrhotic patients (p < 0.001). According to the stepwise Cox regression hazard model analysis, we established nomograms including TBil, albumin, history of HE, ascites grade, sarcopenia, and myosteatosis for easily determining survival probabilities in cirrhotic patients. The AUC is 0.874 (95% CI 0.800-0.949) for 6-month survival, 0.831 (95% CI 0.764-0.898) for 1-year survival, and 0.813 (95% CI 0.756-0.871) for 2-year survival prediction, respectively. CONCLUSIONS: This study provides evidence of the significant correlation between skeletal muscle alterations and poor outcomes of cirrhosis, and establishes valid and convenient nomograms incorporating musculoskeletal disorders for the prognostic prediction of liver cirrhosis. Further large-scale prospective studies are necessary to verify the value of the nomograms.

Genomic and molecular landscape of homologous recombination deficiency across multiple cancer types.

Homologous recombination deficiency (HRD) causes faulty double-strand break repair and is a prevalent cause of tumorigenesis. However, the incidence of HRD and its clinical significance in pan-cancer patients remain unknown. Using computational analysis of Single-nucleotide polymorphism array data from 10,619 cancer patients, we demonstrate that HRD frequently occurs across multiple cancer types. Analysis of the pan-cancer cohort revealed that HRD is not only a biomarker for ovarian cancer and triple-negative breast cancer, but also has clinical prognostic value in numerous cancer types, including adrenocortical cancer and thymoma. We discovered that homologous recombination-related genes have a high mutation or deletion frequency. Pathway analysis shows HRD is positively correlated with the DNA damage response and the immune-related signaling pathways. Single cell RNA sequencing of tumor-infiltrating lymphocytes reveals a significantly higher proportion of exhausted T cells in HRD patients, indicating pre-existing immunity. Finally, HRD could be utilized to predict pan-cancer patients' responses to Programmed cell death protein 1 immunotherapy. In summary, our work establishes a comprehensive map of HRD in pan-cancer. The findings have significant implications for expanding the scope of Poly ADP-ribose polymerase inhibitor therapy and, possibly, immunotherapy.

Anti-oomycete ability of scopolamine against Phytophthora infestans, a terrible pathogen of potato late blight.

BACKGROUND: Phytophthora infestans causes late blight, threatening potato production. The tropane alkaloid scopolamine from some industrial plants (Datura, Atropa, etc.) has a broad-spectrum bacteriostatic effect, but its effect on P. infestans is unknown. RESULTS: In the present study, scopolamine inhibited the mycelial growth of phytopathogenic oomycete P. infestans, and the half-maximal inhibitory concentration (IC50 ) was 4.25 g L-1 . The sporangia germination rates were 61.43%, 16.16%, and 3.99% at concentrations of zero (control), 0.5 IC50 , and IC50 , respectively. The sporangia viability of P. infestans was significantly reduced after scopolamine treatment through propidium iodide and fluorescein diacetate staining, speculating that scopolamine destroyed cell membrane integrity. The detached potato tuber experiment demonstrated that scopolamine lessened the pathogenicity of P. infestans in potato tubers. Under stress conditions, scopolamine showed good inhibition of P. infestans, indicating that scopolamine could be used in multiple adverse conditions. The combination effect of scopolamine and the chemical pesticide Infinito on P. infestans was more effective than the use of scopolamine or Infinito alone. Moreover, transcriptome analysis suggested that scopolamine leaded to a downregulation of most P. infestans genes, functioning in cell growth, cell metabolism, and pathogenicity. CONCLUSION: To our knowledge, this is the first study to detect scopolamine inhibitory activity against P. infestans. Also, our findings highlight the potential of scopolamine as an eco-friendly option for controlling late blight in the future. © 2023 Society of Chemical Industry.

Tunable growth of one-dimensional graphitic materials: graphene nanoribbons, carbon nanotubes, and nanoribbon/nanotube junctions.

Graphene nanoribbons (GNRs) and carbon nanotubes (CNTs), two representative one-dimensional (1D) graphitic materials, have attracted tremendous research interests due to their promising applications for future high-performance nanoelectronics. Although various methods have been developed for fabrication of GNRs or CNTs, a unified method allowing controllable synthesis of both of them, as well as their heterojunctions, which could largely benefit their nano-electronic applications, is still lacking. Here, we report on a generic growth of 1D carbon using nanoparticles catalyzed chemical vapor deposition (CVD) on atomically flat hexagonal boron nitride (h-BN) substrates. Relative ratio of the yielded GNRs and CNTs is able to be arbitrarily tuned by varying the growth temperature or feeding gas pressures. The tunability of the generic growth is quantitatively explained by a competing nucleation theory: nucleation into either GNRs or CNTs by the catalysts is determined by the free energy of their formation, which is controlled by the growth conditions. Under the guidance of the theory, we further realized growth of GNR/CNT intramolecular junctions through changing H2 partial pressure during a single growth process. Our study provides not only a universal and controllable method for growing 1D carbon nanostructures, but also a deep understanding of their growth mechanism, which would largely benefit future carbon-based electronics and optoelectronics.

Catalytic Growth of Ultralong Graphene Nanoribbons on Insulating Substrates.

Graphene nanoribbons (GNRs) with widths of a few nanometers are promising candidates for future nanoelectronic applications due to their structurally tunable bandgaps, ultrahigh carrier mobilities, and exceptional stability. However, the direct growth of micrometer-long GNRs on insulating substrates, which is essential for the fabrication of nanoelectronic devices, remains an immense challenge. Here, the epitaxial growth of GNRs on an insulating hexagonal boron nitride (h-BN) substrate through nanoparticle-catalyzed chemical vapor deposition is reported. Ultranarrow GNRs with lengths of up to 10 µm are synthesized. Remarkably, the as-grown GNRs are crystallographically aligned with the h-BN substrate, forming 1D moiré superlattices. Scanning tunneling microscopy reveals an average width of 2 nm and a typical bandgap of ≈1 eV for similar GNRs grown on conducting graphite substrates. Fully atomistic computational simulations support the experimental results and reveal a competition between the formation of GNRs and carbon nanotubes during the nucleation stage, and van der Waals sliding of the GNRs on the h-BN substrate throughout the growth stage. This study provides a scalable, single-step method for growing micrometer-long narrow GNRs on insulating substrates, thus opening a route to explore the performance of high-quality GNR devices and the fundamental physics of 1D moiré superlattices.

Deleterious Rare Mutations of GLI1 Dysregulate Sonic Hedgehog Signaling in Human Congenital Heart Disease.

The Glioma-associated oncogene (Gli) family members of zinc finger DNA-binding proteins are core effectors of Sonic hedgehog (SHH) signaling pathway. Studies in model organisms have identified that the Gli genes play critical roles during organ development, including the heart, brain, kidneys, etc. Deleterious mutations in GLI genes have previously been revealed in several human developmental disorders, but few in congenital heart disease (CHD). In this study, the mutations in GLI1-3 genes were captured by next generation sequencing in human cohorts composed of 412 individuals with CHD and 213 ethnically matched normal controls. A total of 20 patient-specific nonsynonymous rare mutations in coding regions of human GLI1-3 genes were identified. Functional analyses showed that GLI1 c.820G> T (p.G274C) is a gain-of-function mutation, while GLI1 c.878G>A (p.R293H) and c.1442T>A (p.L481X) are loss-of-function mutations. Our findings suggested that deleterious rare mutations in GLI1 gene broke the balance of the SHH signaling pathway regulation and may constitute a great contribution to human CHD, which shed new light on understanding genetic mechanism of embryo cardiogenesis regulated by SHH signaling.

Scalable and Versatile Transfer of Sensitive Two-dimensional Materials.

Damage-free transfer of large-area two-dimensional (2D) materials is indispensable to unleash their full potentials in a wide range of electronic, photonic, and biochemical applications. However, the all-surface nature of 2D materials renders many of them vulnerable to surrounding environments, especially etchants and water involved during wet transfer process. Up to now, a scalable and damage-free transfer method for sensitive 2D materials is still lacking. Here, we report a general damage-free transfer method for sensitive 2D materials. The as-transferred 2D materials exhibit well-preserved structural integrity and unaltered physical properties. We further develop a facile TEM sample preparation technique that allows direct recycling of materials on TEM grids with high fidelity. This recycling technique provides an unprecedented opportunity to precisely relate structural characterization with physical/chemical/electrical probing for the same samples. This method can be readily generalized to diverse nanomaterials for large-area damage-free transfer and enables in-depth investigation of structure-property relationship.