Atomically Resolved Transition Pathways of Iron Redox.

The redox transition between iron and its oxides is of the utmost importance in heterogeneous catalysis, biological metabolism, and geological evolution. The structural characteristics of this reaction may vary based on surrounding environmental conditions, giving rise to diverse physical scenarios. In this study, we explore the atomic-scale transformation of nanosized Fe3O4 under ambient-pressure H2 gas using in-situ environmental transmission electron microscopy. Our results reveal that the internal solid-state reactions dominated by iron diffusion are coupled with the surface reactions involving gaseous O or H species. During reduction, we observe two competitive reduction pathways, namely Fe3O4 → FeO → Fe and Fe3O4 → Fe. An intermediate phase with vacancy ordering is observed during the disproportionation reaction of Fe2+ → Fe0 + Fe3+, which potentially alleviates stress and facilitates ion migration. As the temperature decreases, an oxidation process occurs in the presence of environmental H2O and trace amounts of O2. A direct oxidation of Fe to Fe3O4 occurs in the absence of the FeO phase, likely corresponding to a change in the water vapor content in the atmosphere. This work elucidates a full dynamical scenario of iron redox under realistic conditions, which is critical for unraveling the intricate mechanisms governing the solid-solid and solid-gas reactions.

Efficacy and Safety of Vaccines to Prevent Respiratory Syncytial Virus Infection in Infants and Older Adults: A Systematic Review and Meta-analysis.

OBJECTIVES: To determine the efficacy and safety of respiratory syncytial virus (RSV) vaccines in infants and older adults. METHODS: We performed a systematic review and meta-analysis of randomized control trials that evaluated the efficacy of maternal RSV immunization against infections in infants, as well as the efficacy of RSV vaccines in older adults. The primary outcome was the vaccine efficacy against RSV-related lower respiratory tract disease (LRTD). GRADE criteria was used to evaluate the level of evidence. RESULTS: Ten trials were included in the review. For maternal vaccination, the RSV vaccine showed favourable efficacy against RSV-related LRTD (vaccine efficacy 57.3%, 95% CI 31.3 to 73.5; low certainty) and RSV-related severe LRTD (vaccine efficacy 81.9%, 95% CI 56.8 to 92.4; moderate certainty) in infants within 90 days after birth. For older adults, Meta-analysis showed that RSV vaccines could also reduce the risk of RSV-related LRTD (vaccine efficacy 78.3%, 95% CI 65.6 to 86.3; moderate certainty) and RSV-related severe LRTD (vaccine efficacy 86.5%, 95% CI 68.3 to 94.3; moderate certainty). There was no significant difference in serious adverse events between RSV vaccines and placebo. CONCLUSION: RSV vaccines have the potential to offer protection against RSV disease in both infants and older adults, without apparent safety concerns.

An all-metallic nanovesicle for hydrogen oxidation.

Vesicle, a microscopic unit that encloses a volume with an ultrathin wall, is ubiquitous in biomaterials. However, it remains a huge challenge to create its inorganic metal-based artificial counterparts. Here, inspired by the formation of biological vesicles, we proposed a novel biomimetic strategy of curling the ultrathin nanosheets into nanovesicles, which was driven by the interfacial strain. Trapped by the interfacial strain between the initially formed substrate Rh layer and subsequently formed RhRu overlayer, the nanosheet begins to deform in order to release a certain amount of strain. Density functional theory (DFT) calculations reveal that the Ru atoms make the curling of nanosheets more favorable in thermodynamics applications. Owing to the unique vesicular structure, the RhRu nanovesicles/C displays excellent hydrogen oxidation reaction (HOR) activity and stability, which has been proven by both experiments and DFT calculations. Specifically, the HOR mass activity of RhRu nanovesicles/C are 7.52 A mg(Rh+Ru)-1 at an overpotential of 50 mV at the rotating disk electrode (RDE) level; this is 24.19 times that of commercial Pt/C (0.31 mA mgPt-1). Moreover, the hydroxide exchange membrane fuel cell (HEMFC) with RhRu nanovesicles/C displays a peak power density of 1.62 W cm-2 in the H2-O2 condition, much better than that of commercial Pt/C (1.18 W cm-2). This work creates a new biomimetic strategy to synthesize inorganic nanomaterials, paving a pathway for designing catalytic reactors.

Pharmacologic and Nutritional Interventions for Early Alzheimer's Disease: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials.

Background: Early intervention is essential for meaningful disease modification in Alzheimer's disease (AD). Objective: We aimed to determine the efficacy and safety of pharmacologic and nutritional interventions for early AD. Methods: PubMed, Embase, the Cochrane Library, and ClinicalTrials.gov were searched from database inception until 1 September 2023. We included randomized controlled trials that evaluated the efficacy of interventions in early AD. Only interventions that demonstrated efficacy compared to placebo were included in the network meta-analysis (NMA). Then we performed frequentist fixed-effects NMA to rank the interventions. GRADE criteria were used to evaluate the level of evidence. Results: Fifty-eight trials including a total of 33,864 participants and 48 interventions were eligible for inclusion. Among the 48 interventions analyzed, only 6 (12.5%) treatments- ranging from low to high certainty- showed significant improvement in cognitive decline compared to placebo. High certainty evidence indicated that donanemab (standardized mean difference [SMD] -0.239, 95% confidence interval [CI] -0.343 to -0.134) and lecanemab (SMD -0.194, 95% CI -0.279 to -0.108) moderately slowed the clinical progression in patients with amyloid pathology. Additionally, methylphenidate, donepezil, LipiDiDiet, and aducanumab with low certainty showed significant improvement in cognitive decline compared to placebo. However, there was no significant difference in serious adverse events as reported between the six interventions and placebo. Conclusions: Only 12.5% of interventions studied demonstrated efficacy in reducing cognitive impairment in early AD. Donanemab and lecanemab have the potential to moderately slow the clinical progression in patients with amyloid pathology. Further evidence is required for early intervention in AD.

Vitamin D supplementation for prevention of acute respiratory infections in older adults: A systematic review and meta-analysis.

BACKGROUND: Acute respiratory infections (ARIs) have a substantial impact on morbidity, healthcare utilization, and functional decline among older adults. Therefore, we systematically reviewed evidence from randomized controlled trials (RCTs) to evaluate the efficacy and safety of vitamin D supplementation in preventing ARIs in older adults. METHODS: PubMed, Embase, the Cochrane Library, and ClinicalTrials.gov were searched until 1 February 2024. RCTs evaluating the use of vitamin D supplements to protect older adults from ARIs were included. Two reviewers independently screened papers, extracted the data and assessed the risk of bias. Data were summarised as relative risks (RRs) or odds ratios (ORs) with corresponding 95% confidence intervals (CIs). Random effects meta-analyses were used to synthesise the results. GRADE was used to evaluate the quality of evidence. All the analysis were performed with Stata version 17. RESULTS: Twelve trials (41552 participants) were included in the meta-analysis. It showed that vitamin D supplementation probably does not reduce the incidence of ARIs (RR, 0.99; 95% CI, 0.97-1.02, I2 = 0%; moderate certainty). No significant effect of vitamin D supplementation on the risk of ARI was observed for any of the subgroups defined by baseline 25(OH)D concentration, control treatments, dose frequency, study duration, and participants' condition. However, there was a possibility, although not statistically significant, that vitamin D may reduce the risk of ARI in patients with a baseline 25(OH)D concentration <50 nmol/L (OR, 0.90; 95% CI, 0.79-1.04, I2 = 14.7%). Additionally, vitamin D supplements might result in little to no difference in death due to any cause, any adverse event, hypercalcinemia, and kidney stones. CONCLUSIONS: Vitamin D supplementation among older adults probably results in little to no difference in the incidence of ARIs. However, further evidence is needed, particularly for individuals with vitamin D deficiency and populations residing in low and middle income countries. TRIAL REGISTRATION: This study was registered on PROSPERO (CRD42023451265).

Penehyclidine hydrochloride alleviates LPS-induced inflammatory responses and oxidative stress via ROS/Nrf2/HO-1 activation in RAW264.7 cells.

BACKGROUND: Inflammation is a biological response of the immune system to harmful stimuli. Penehyclidine hydrochloride (PCH) can alleviate inflammation and oxidative stress by activating reactive oxygen species (ROS), nuclear factor erythroid 2-related factor (Nrf2) and heme oxygenase 1 (HO-1) in animal models, but there is a lack of cellular evidence. OBJECTIVES: This study investigated the effects of PHC on lipopolysaccharide (LPS)-induced inflammation response and oxidative stress in RAW264.7 cells. MATERIAL AND METHODS: RAW264.7 cells were treated with 1 µg/mL or 5 µg/mL of PHC, with interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), IL-1ß, and prostaglandin E2 (PGE2) levels measured with enzyme-linked immunosorbent assay (ELISA) and nitric oxide (NO) measured using the Griess test. Reactive oxygen species were examined with flow cytometry and immunofluorescence, and b-related factor 2 (BRF-2) and NAD(P)H-quinone oxidoreductase 1 (NQO1) using western blot. RESULTS: Penehyclidine hydrochloride partly, but substantially, reversed LPS-related NO and PGE2 production by RAW264.7 cells in a dose-dependent manner and suppressed LPS-induced expression of IL-6, TNF-α and IL-1ß messenger ribonucleic acid (mRNA), secretion of IL-6, TNF-α and IL-1ß, and ROS production. Lipopolysaccharide stimulation did not affect Nrf2, heme oxygenase 1 (HO-1) or NQO1 protein expression in RWA264.7 cells not treated with PHC. However, PHC treatment significantly elevated Nrf2, HO-1 and NQO1 protein in LPS-treated RWA264.7 cells, an effect that was dose-dependent. The ROS scavenging using N-acetyl-L-cysteine abolished the PHC-induced upregulation of Nrf2 and HO-1. CONCLUSIONS: Penehyclidine hydrochloride may alleviate LPS-induced inflammation and oxidative stress by activating Nrf2 signaling in RAW264.7 macrophages. These findings suggest that PHC could alleviate inflammation by targeting activated macrophages.

Wrist Arthroscopy-Assisted Reduction for Distal Radius Fracture and its Associated Injuries: Clinical Observation of Triangular Fibrocartilage Complex Injuries.

BACKGROUND: To compare the clinical effects between wrist arthroscopy-assisted open reduction plus internal fixation, using the triangular fibrocartilage complex (TFCC) as an example, and simple open reduction plus internal fixation in the treatment of distal radius fractures (DRFs). The study aims to assess the efficacy of arthroscopic-assisted open reduction and internal fixation in treating distal radius fractures. METHODS: The study utilized a retrospective cohort research approach, involving 60 patients treated at Binzhou Medical University Hospital between August 2021 and October 2022. These patients met the specified criteria and underwent two distinct surgical procedures for DRFs. Prior to surgery, thorough communication was established with the patients to elucidate the advantages, risks, and associated costs of wrist arthroscopy, and informed consent was obtained. Subsequent to the surgeries, postoperative follow-up was conducted to evaluate the variances between the two treatment modalities. Postoperative analysis and assessment encompassed the patients' Visual Analogue Scale (VAS) scores, Cooney wrist scores, grip strength of the affected limb (in comparison with the healthy side), wrist range of motion, and the frequency of intraoperative fluoroscopy usage. RESULTS: No surgical complications were observed among all patients. They were followed up for an average duration of (12.1 ± 1.3) months postoperatively, during which all fractures healed successfully. Within the treatment group, arthroscopy detected 14 cases of TFCC tears during the operation, all of which were repaired under a microscope. Conversely, physical examination identified three cases of TFCC injury in the control group, which were treated via incision and suture. At the 3-month postoperative mark, the treatment group exhibited significantly superior comprehensive scores for wrist pain, grip strength, and wrist range of motion compared to the control group (p < 0.05). Cooney's comprehensive wrist joint scoring yielded the following results: treatment group - excellent in 21 cases, good in five cases, and moderate in four cases; control group - excellent in 16 cases, good in nine cases, and moderate in five cases. CONCLUSION: Wrist arthroscopy-assisted surgery facilitates precise reduction of the articular surface and alleviation of intraarticular congestion. Moreover, it enables evaluation and repair of concurrent intra-articular injuries such as TFCC tears and other tissue injuries, thereby reducing the likelihood of chronic wrist pain. Consequently, this technique should be deemed valuable in clinical practice owing to its outstanding clinical efficacy.

Automatic center identification of electron diffraction with multi-scale transformer networks.

Selected area electron diffraction (SAED) is a widely used technique for characterizing the structure and measuring lattice parameters of materials. An autonomous analytic method has become an urgent demand for the large-scale SAED data produced from in-situ experiments. In this work, we realize the automatic processing for center identification with a proposed deep segmentation model named the multi-scale Transformer (MS-Trans) network. This algorithm enables robust segmentation of the central spots by combining a novel gated axial-attention module and multi-scale feature fusion. The proposed MS-Trans model shows high precision and robustness, enabling autonomous processing of SAED patterns without any prior knowledge. The application on in-situ SAED data of the oxidation process of FeNi alloy demonstrates its capability of implementing autonomous quantitative processing. © 2017 Elsevier Inc. All rights reserved.

NIR-triggered bacterial cellulose-based wound dressings for multiple synergistic therapy of infected wound.

Skin wounds are repaired by a complex series of events and overlapping phases in which bacterial infection and insufficient angiogenesis at the wound site delay the healing process. Thus, functional wound dressings with enhanced antibacterial activity and angiogenic capacity have attracted attention. Herein, bacterial cellulose (BC)-based dressings were successfully fabricated by functionalization with a polydopamine (PDA) coating and copper sulfide nanoparticles (CuS NPs). Under 808 nm laser illumination, the BC/PDA/CuS composite membranes exhibited outstanding adjustable photothermal and photodynamic activities as well as controlled Cu2+ release, endowing the composite membranes with synergetic antibacterial activity. Specially, a bactericidal efficiency of 99.7 % and 88.0 % for Staphylococcus aureus and Escherichia coli was achieved after treatment with BC/PDA/CuS5 sample under NIR irradiation (0.8 W/cm2, 10 min), respectively. Moreover, the BC/PDA/CuS5 composite membrane could enhance the angiogenesis due to the released Cu2+. In vivo experiments revealed that the BC/PDA/CuS5 composite membrane dressing could accelerate the wound closure process of the full-thickness skin defects with S. aureus by synergistically reducing inflammation, enhancing collagen deposition, and promoting vascularization under NIR irradiation. Additionally, the BC/PDA/CuS5 composite membrane exhibited high biocompatibility and biosafety. This work offers a new strategy to prepare multifunctional BC-based dressing for clinical wound healing.

Si-Based High-Entropy Anode for Lithium-Ion Batteries.

Up to now, only a small portion of Si has been utilized in the anode for commercial lithium-ion batteries (LIBs) despite its high energy density. The main challenge of using micron-sized Si anode is the particle crack and pulverization due to the volume expansion during cycling. This work proposes a type of Si-based high-entropy alloy (HEA) materials with high structural stability for the LIB anode. Micron-sized HEA-Si anode can deliver a capacity of 971 mAhg-1 and retains 93.5% of its capacity after 100 cycles. In contrast, the silicon-germanium anode only retains 15% of its capacity after 20 cycles. This study has discovered that including HEA elements in Si-based anode can decrease its anisotropic stress and consequently enhance ductility at discharged state. By utilizing in situ X-ray diffraction and transmission electron microscopy analyses, a high-entropy transition metal doped Lix (Si/Ge) phase is found at lithiated anode, which returns to the pristine HEA phase after delithiation. The reversible lithiation and delithiation process between the HEA phases leads to intrinsic stability during cycling. These findings suggest that incorporating high-entropy modification is a promising approach in designing anode materials toward high-energy density LIBs.

Defective ZnIn2S4 Nanosheets for Visible-Light and Sacrificial-Agent-Free H2O2 Photosynthesis via O2/H2O Redox.

H2O2 photosynthesis has attracted great interest in harvesting and converting solar energy to chemical energy. Nevertheless, the high-efficiency process of H2O2 photosynthesis is driven by the low H2O2 productivity due to the recombination of photogenerated electron-hole pairs, especially in the absence of a sacrificial agent. In this work, we demonstrate that ultrathin ZnIn2S4 nanosheets with S vacancies (Sv-ZIS) can serve as highly efficient catalysts for H2O2 photosynthesis via O2/H2O redox. Mechanism studies confirm that Sv in ZIS can extend the lifetimes of photogenerated carriers and suppress their recombination, which triggers the O2 reduction and H2O oxidation to H2O2 through radical initiation. Theoretical calculations suggest that the formation of Sv can strongly change the coordination structure of ZIS, modulating the adsorption abilities to intermediates and avoiding the overoxidation of H2O to O2 during O2/H2O redox, synergistically promoting 2e- O2 reduction and 2e- H2O oxidation for ultrahigh H2O2 productivity. The optimal catalyst displays a H2O2 productivity of 1706.4 µmol g-1 h-1 under visible-light irradiation without a sacrificial agent, which is ∼29 times higher than that of pristine ZIS (59.4 µmol g-1 h-1) and even much higher than those of reported photocatalysts. Impressively, the apparent quantum efficiency is up to 9.9% at 420 nm, and the solar-to-chemical conversion efficiency reaches ∼0.81%, significantly higher than the value for natural synthetic plants (∼0.10%). This work provides a facile strategy to separate the photogenerated electron-hole pairs of ZIS for H2O2 photosynthesis, which may promote fundamental research on solar energy harvest and conversion.

Detection of CSTF2 by nano fluorescent probe and its correlation with malignant biological characteristics in liver cancer.

To develop a novel nano DNA fluorescent probe for in situ detection of CSTF2 in liver cancer (LC) and study its correlation with the development of LC, we developed nano-TiO2-DNA fluorescent probe which can bind with CSTF2 in LC samples with high efficiency. The detection process of CSTF2 did not involve the use PCR technology, and the concentration of CSTF2 can be directly observed by fluorescence intensity. This probe exhibited excellent physicochemical properties in ethyl alcohol at -20°C and could directly and selectively permeate into Hep-3B cells. By using CSTF2 Nano-TiO2-DNA probe, we found that the CSTF2 level increased greatly in LC tissue and cells, and high CSTF2 level was closely associated with high levels of tumor markers and poor prognosis in LC patients. After transfection, CSTF2 was overexpressed or silenced in Hep-3B cells, and we find that high CSTF2 level effectively increased the activity and invasion of Hep-3B cells and reduced their apoptosis. Furthermore, high CSTF2 level significantly increased the tumor volume and weight in mice models by activating PI3K/AKT/mTOR signal pathway. Therefore, CSTF2 can serve as an early biomarker of LC and a novel potential target for its treatment.

Function and regulation of ubiquitin-like SUMO system in heart.

The small ubiquitin-related modifier (SUMOylation) system is a conserved, reversible, post-translational protein modification pathway covalently attached to the lysine residues of proteins in eukaryotic cells, and SUMOylation is catalyzed by SUMO-specific activating enzyme (E1), binding enzyme (E2) and ligase (E3). Sentrin-specific proteases (SENPs) can cleave the isopeptide bond of a SUMO conjugate and catalyze the deSUMOylation reaction. SUMOylation can regulate the activity of proteins in many important cellular processes, including transcriptional regulation, cell cycle progression, signal transduction, DNA damage repair and protein stability. Biological experiments in vivo and in vitro have confirmed the key role of the SUMO conjugation/deconjugation system in energy metabolism, Ca2+ cycle homeostasis and protein quality control in cardiomyocytes. In this review, we summarized the research progress of the SUMO conjugation/deconjugation system and SUMOylation-mediated cardiac actions based on related studies published in recent years, and highlighted the further research areas to clarify the role of the SUMO system in the heart by using emerging technologies.

Fetal echocardiography changes of the right ventricle of well-controlled gestational diabetes mellitus.

BACKGROUND: There is few evidence of right ventricular (RV) function in fetuses with gestational diabetes mellitus (GDM). Therefore, the aim of this study was to assess the RV function of fetuses using routine and two-dimensional speckle-tracking echocardiography (2D STE) to determine the effects of well-controlled GDM in the third trimester. METHODS: We used a Philips Epiq7C ultrasound instrument to obtain RV data sets from 63 subjects from July 2019 to February 2022. We compared the free wall thickness (FWT), fractional area change (FAC), Tei index (TEI), tricuspid annular plane systolic excursion (TAPSE) and free wall longitudinal strain(FWLS)of the RV in mothers with well-controlled GDM and normal gestational age-matched fetuses. RESULTS: 63 third trimester fetuses (32 GDM; 31 healthy controls) met the enrolment criteria. Significant differences in fetal RV were detected between the GDM and control groups for the FAC (36.35 ± 6.19 vs. 41.59 ± 9.11; P = 0.008) and the FWLS (-18.28 ± 4.23 vs. -20.98 ± 5.49; P = 0.021). There was a significant difference among the segmental strains of the base, middle and apex of the RV free wall in the healthy controls (P = 0.003), but in the GDM group, there was no statistical difference (p = 0.076). RV FWLS had a strong correlation with FAC (r = 0.467; P = 0.0002). CONCLUSIONS: In well-controlled GDM, there was measurable fetal RV hypertrophy and significant systolic function decline, indicating the presence of ventricular remodeling and dysfunction. 2D-STE can evaluate the RV free wall contraction in a more comprehensive way.

Kinetic Limits of Graphite Anode for Fast-Charging Lithium-Ion Batteries.

Fast-charging lithium-ion batteries are highly required, especially in reducing the mileage anxiety of the widespread electric vehicles. One of the biggest bottlenecks lies in the sluggish kinetics of the Li+ intercalation into the graphite anode; slow intercalation will lead to lithium metal plating, severe side reactions, and safety concerns. The premise to solve these problems is to fully understand the reaction pathways and rate-determining steps of graphite during fast Li+ intercalation. Herein, we compare the Li+ diffusion through the graphite particle, interface, and electrode, uncover the structure of the lithiated graphite at high current densities, and correlate them with the reaction kinetics and electrochemical performances. It is found that the rate-determining steps are highly dependent on the particle size, interphase property, and electrode configuration. Insufficient Li+ diffusion leads to high polarization, incomplete intercalation, and the coexistence of several staging structures. Interfacial Li+ diffusion and electrode transportation are the main rate-determining steps if the particle size is less than 10 µm. The former is highly dependent on the electrolyte chemistry and can be enhanced by constructing a fluorinated interphase. Our findings enrich the understanding of the graphite structural evolution during rapid Li+ intercalation, decipher the bottleneck for the sluggish reaction kinetics, and provide strategic guidelines to boost the fast-charging performance of graphite anode.

Misoriented high-entropy iridium ruthenium oxide for acidic water splitting.

Designing an efficient catalyst for acidic oxygen evolution reaction (OER) is of critical importance in manipulating proton exchange membrane water electrolyzer (PEMWE) for hydrogen production. Here, we report a fast, nonequilibrium strategy to synthesize quinary high-entropy ruthenium iridium-based oxide (M-RuIrFeCoNiO2) with abundant grain boundaries (GB), which exhibits a low overpotential of 189 millivolts at 10 milliamperes per square centimeter for OER in 0.5 M H2SO4. Microstructural analyses, density functional calculations, and isotope-labeled differential electrochemical mass spectroscopy measurements collectively reveal that the integration of foreign metal elements and GB is responsible for the enhancement of activity and stability of RuO2 toward OER. A PEMWE using M-RuIrFeCoNiO2 catalyst can steadily operate at a large current density of 1 ampere per square centimeter for over 500 hours. This work demonstrates a pathway to design high-performance OER electrocatalysts by integrating the advantages of various components and GB, which breaks the limits of thermodynamic solubility for different metal elements.

Multifunctional Asymmetric Bacterial Cellulose Membrane with Enhanced Anti-Bacterial and Anti-Inflammatory Activities for Promoting Infected Wound Healing.

An asymmetric wound dressing acts as a skin-like structure serves as a protective barrier between a wound and its surroundings. It allows for the absorption of tissue fluids and the release of active substances at the wound site, thus speeding up the healing process. However, the production of such wound dressings requires the acquisition of specialized tools, expensive polymers, and solvents that contain harmful byproducts. In this study, an asymmetric bacterial cellulose (ABC) wound dressing using starch as a porogen has been developed. By incorporating silver-metal organic frameworks (Ag-MOF) and curcumin into the ABC membrane, the wound dressing gains antioxidant, reactive oxygen species (ROS) scavenging, and anti-bacterial activities. Compared to BC-based wound dressings, this dressing promotes efficient dissolution and controlled release of curcumin and silver ions. In a full-thickness skin defect model, wound dressing not only inhibits the growth of bacteria on infected wounds but also regulates the release of curcumin to reduce inflammation and promote the production of epithelium, blood vessels, and collagen. Consequently, this dressing provides superior wound treatment compared to BC-based dressing.

Approaching Ohmic Contacts for Ideal Monolayer MoS2 Transistors Through Sulfur-Vacancy Engineering.

Field-effect transistors (FETs) made of monolayer 2D semiconductors (e.g., MoS2 ) are among the basis of the future modern wafer chip industry. However, unusually high contact resistances at the metal-semiconductor interfaces have seriously limited the improvement of monolayer 2D semiconductor FETs so far. Here, a high-scale processable strategy is reported to achieve ohmic contact between the metal and monolayer MoS2 with a large number of sulfur vacancies (SVs) by using simple sulfur-vacancy engineering. Due to the successful doping of the contact regions by introducing SVs, the contact resistance of monolayer MoS2 FET is as low as 1.7 kΩ·µm. This low contact resistance enables high-performance MoS2 FETs with ultrahigh carrier mobility of 153 cm2 V-1 s-1 , a large on/off ratio of 4 × 109 , and high saturation current of 342 µA µm-1 . With the comprehensive investigation of different SV concentrations by adjusting the plasma duration, it is also demonstrated that the SV-increased electron doping, with its resulting reduced Schottky barrier, is the dominant factor driving enhanced electrical performance. The work provides a simple method to promote the development of industrialized atomically thin integrated circuits.