Uniform Synthesis of Bilayer Hydrogen Substituted Graphdiyne for Flexible Piezoresistive Applications.

Graphdiyne (GDY) has garnered significant attention as a cutting-edge 2D material owing to its distinctive electronic, optoelectronic, and mechanical properties, including high mobility, direct bandgap, and remarkable flexibility. One of the key challenges hindering the implementation of this material in flexible applications is its large area and uniform synthesis. The facile growth of centimeter-scale bilayer hydrogen substituted graphdiyne (Bi-HsGDY) on germanium (Ge) substrate is achieved using a low-temperature chemical vapor deposition (CVD) method. This material's field effect transistors (FET) showcase a high carrier mobility of 52.6 cm2  V-1  s-1 and an exceptionally low contact resistance of 10 Ω µm. By transferring the as-grown Bi-HsGDY onto a flexible substrate, a long-distance piezoresistive strain sensor is demonstrated, which exhibits a remarkable gauge factor of 43.34 with a fast response time of ≈275 ms. As a proof of concept, communication by means of Morse code is implemented using a Bi-HsGDY strain sensor. It is believed that these results are anticipated to open new horizons in realizing Bi-HsGDY for innovative flexible device applications.

Uncertainty and Irreproducibility of Triboelectricity Based on Interface Mechanochemistry.

Triboelectrification mechanism is still not understood, despite centuries of investigations. Here, we propose a model showing that mechanochemistry is key to elucidate triboelectrification fundamental properties. Studying contact between gold and silicate glasses, we observe that the experimental triboelectric output is subject to large variations and polarity inversions. First principles analysis shows that electronic transfer is activated by mechanochemistry and the tribopolarity is determined by the termination exposed to contact, depending on the material composition, which can result in different charging at the macroscale. The electron transfer mechanism is driven by the interface barrier dynamics, regulated by mechanical forces. The model provides a unified framework to explain several experimental observations, including the systematic variations in the triboelectric output and the mixed positive-negative "mosaic" charging patterns, and paves the way to the theoretical prediction of the triboelectric properties.

Prevalence, incidence, and outcomes of hepatitis E virus coinfection in patients with chronic hepatitis C.

This study aimed to elucidate the anti-hepatitis E virus (HEV) immunoglobulin G (IgG) prevalence and incidence of seroconversion and seroreversion as well as its risk factors and to analyze the clinical outcomes of HEV and hepatitis C virus (HCV) coinfected patients compared to those of HCV-monoinfected patients. We prospectively enrolled 502 viremic HCV patients with paired plasma samples (at intervals of ≥ 12 months) from 5 tertiary hospitals. Anti-HEV IgG positivity was tested using the Wantai ELISA kit in all paired samples. Mean age was 58.2 ± 11.5 years old, 48.2% were male, 29.9% of patients had liver cirrhosis, and 9.4% of patients were diagnosed with hepatocellular carcinoma (HCC). The overall prevalence of anti-HEV IgG positivity at enrollment was 33.3%, with a higher prevalence in males and increasing prevalence according to the subject's age. During the 916.4 person-year, the HEV incidence rate was 0.98/100 person-years (9/335, 2.7%). Hepatic decompensation or liver-related mortality was not observed. There were six seroreversion cases among 172 anti-HEV-positive patients (1.22/100 person-years). In conclusion, approximately one-third of the adult Korean chronic HCV patients were anti-HEV IgG positive. The HEV incidence rate was 1 in 100 persons per year, without adverse hepatic outcomes or mortality.

Enhanced Hydro-Actuation and Capacitance of Electrochemically Inner-Bundle-Activated Carbon Nanotube Yarns.

Recently, several attempts have been made to activate or functionalize macroscopic carbon nanotube (CNT) yarns to enhance their innate abilities. However, a more homogeneous and holistic activation approach that reflects the individual nanotubes constituting the yarns is crucial. Herein, a facile strategy is reported to maximize the intrinsic properties of CNTs assembled in yarns through an electrochemical inner-bundle activation (EIBA) process. The as-prepared neat CNT yarns are two-end tethered and subjected to an electrochemical voltage (vs Ag/AgCl) in aqueous electrolyte systems. Massive electrolyte infiltration during the EIBA causes swelling of the CNT interlayers owing to the tethering and subsequent yarn shrinkage after drying, suggesting activation of the entire yarn. The EIBA-treated CNT yarns functionalized with oxygen-containing groups exhibit enhanced wettability without significant loss of their physical properties. The EIBA effect of the CNTs is experimentally demonstrated by hydration-driven torsional actuation (∼986 revolutions/m) and a drastic capacitance improvement (approximately 25-fold).

High-Performance Perovskite Quantum Dot Solar Cells Enabled by Incorporation with Dimensionally Engineered Organic Semiconductor.

Perovskite quantum dots (PQDs) have been considered promising and effective photovoltaic absorber due to their superior optoelectronic properties and inherent material merits combining perovskites and QDs. However, they exhibit low moisture stability at room humidity (20-30%) owing to many surface defect sites generated by inefficient ligand exchange process. These surface traps must be re-passivated to improve both charge transport ability and moisture stability. To address this issue, PQD-organic semiconductor hybrid solar cells with suitable electrical properties and functional groups might dramatically improve the charge extraction and defect passivation. Conventional organic semiconductors are typically low-dimensional (1D and 2D) and prone to excessive self-aggregation, which limits chemical interaction with PQDs. In this work, we designed a new 3D star-shaped semiconducting material (Star-TrCN) to enhance the compatibility with PQDs. The robust bonding with Star-TrCN and PQDs is demonstrated by theoretical modeling and experimental validation. The Star-TrCN-PQD hybrid films show improved cubic-phase stability of CsPbI3-PQDs via reduced surface trap states and suppressed moisture penetration. As a result, the resultant devices not only achieve remarkable device stability over 1000 h at 20-30% relative humidity, but also boost power conversion efficiency up to 16.0% via forming a cascade energy band structure.

High-Power Hydro-Actuators Fabricated from Biomimetic Carbon Nanotube Coiled Yarns with Fast Electrothermal Recovery.

Bioinspired yarn/fiber structured hydro-actuators have recently attracted significant attention. However, most water-driven mechanical actuators are unsatisfactory because of the slow recovery process and low full-time power density. A rapidly recoverable high-power hydro-actuator is reported by designing biomimetic carbon nanotube (CNT) yarns. The hydrophilic CNT (HCNT) coiled yarn was prepared by storing pre-twist into CNT sheets and subsequent electrochemical oxidation (ECO) treatment. The resulting yarn demonstrated structural stability even when one end was cut off without the possible loss of pre-stored twists. The HCNT coiled yarn actuators provided maximal contractile work of 863 J/kg at 11.8 MPa stress when driven by water. Moreover, the recovery time of electrically heated yarns at a direct current voltage of 5 V was 95% shorter than that of neat yarns without electric heating. Finally, the electrothermally recoverable hydro-actuators showed a high actuation frequency (0.17 Hz) and full-time power density (143.8 W/kg).

Twist-Stabilized, Coiled Carbon Nanotube Yarns with Enhanced Capacitance.

Coil-structured carbon nanotube (CNT) yarns have recently attracted considerable attention. However, structural instability due to heavy twist insertion, and inherent hydrophobicity restrict its wider application. We report a twist-stable and hydrophilic coiled CNT yarn produced by the facile electrochemical oxidation (ECO) method. The ECO-treated coiled CNT yarn is prepared by applying low potentiostatic voltages (3.0-4.5 V vs Ag/AgCl) between the coiled CNT yarn and a counter electrode immersed in an electrolyte for 10-30 s. Notably, a large volume expansion of the coiled CNT yarns prepared by electrochemical charge injection produces morphological changes, such as surface microbuckling and large reductions in the yarn bias angle and diameter, resulting in the twist-stability of the dried ECO-treated coiled CNT yarns with increased yarn density. The resulting yarns are well functionalized with oxygen-containing groups; they exhibit extrinsic hydrophilicity and significantly improved capacitance (approximately 17-fold). We quantitatively explain the origin of the capacitance improvement using theoretical simulations and experimental observations. Stretchable supercapacitors fabricated with the ECO-treated coiled CNT yarns show high capacitance (12.48 mF/cm and 172.93 mF/cm2, respectively) and great stretchability (80%). Moreover, the ECO-treated coiled CNT yarns are strong enough to be woven into a mask as wearable supercapacitors.

A Hierarchically Tailored Wrinkled Three-Dimensional Foam for Enhanced Elastic Supercapacitor Electrodes.

Recently, three-dimensional (3D) porous foams have been studied, but further improvement in nanoscale surface area and stretchability is required for electronic and energy applications. Herein, a general strategy is reported to form a tailored wrinkling structure on strut surfaces inside a 3D polydimethylsiloxane (PDMS) polymeric foam. Controlled wrinkles are created on the struts of 3D foam through an oxygen plasma treatment to form a bilayer surface of PDMS on uniaxially prestretched 3D PDMS foam, followed by relaxation. After plasma treatment for 1 h and prestretching of 40%, the wrinkled 3D foam greatly improves specific surface area and stretchability by over 60% and 75%, respectively, compared with the pristine 3D PDMS foam. To prove its applicability with improved performances, supercapacitors are prepared by coating a conductive material on the wrinkled 3D foam. The resulting supercapacitors exhibit an increased storage capacity (8.3 times larger), maintaining storage capacity well under stretching up to 50%.

The usefulness and feasibility of placing a clinch knot with a guidewire to achieve temporary hemostasis in arteriovenous dialysis access interventions.

PURPOSE: To evaluate the usefulness and feasibility of using a reversible clinch knot with a guidewire in place rather than eliminating the access route during an arteriovenous hemodialysis access (AV access) intervention using the facing sheath technique. MATERIAL AND METHODS: From July 2016 to June 2019, we retrospectively studied 78 sessions performed as interventional treatment for arteriovenous (AV) hemodialysis (HD) access using the "facing-sheath technique." In all sessions, all antegrade sheaths were removed while a 0.035-inch guidewire remained in place with purse-string suture and the clinch knot. Seventy-two sessions were performed in patients with thrombosed AV accesses (69 arteriovenous grafts [AVGs] and three arteriovenous fistulas [AVFs]), and six sessions were carried out to treat non-thrombosed AV accesses (four AVGs and two AVFs). We evaluated whether proper hemostasis and successful reinsertion of the sheath over the wire into the clinch knot was achieved. Clinical success was defined as achieving prompt restoration of blood flow for AV access, and the postintervention primary and secondary patency were also evaluated. RESULT: In all 87 clinch knots created in 78 total sessions, proper hemostasis was achieved. All clinch knots that required reversal for additional procedures were successfully reopened (55 clinch knots in 50 sessions). The postintervention primary patency rates at 1, 3, and 6 months, and at 1 year were 77.8%, 68.9%, 55.6%, and 33.3%, respectively. The postintervention secondary patency rates at 1, 3, and 6 months, and also at 1 year were 93.3%, 91.1%, 86.7%, and 86.7%, respectively. CONCLUSION: Our AV access intervention which used a clinch knot with purse-string suture while the guidewire remained in place was both useful and feasible for maintaining temporary hemostasis.

Quasi-Binary Transition Metal Dichalcogenide Alloys: Thermodynamic Stability Prediction, Scalable Synthesis, and Application.

Transition metal dichalcogenide (TMDCs) alloys could have a wide range of physical and chemical properties, ranging from charge density waves to superconductivity and electrochemical activities. While many exciting behaviors of unary TMDCs have been demonstrated, the vast compositional space of TMDC alloys has remained largely unexplored due to the lack of understanding regarding their stability when accommodating different cations or chalcogens in a single-phase. Here, a theory-guided synthesis approach is reported to achieve unexplored quasi-binary TMDC alloys through computationally predicted stability maps. Equilibrium temperature-composition phase diagrams using first-principles calculations are generated to identify the stability of 25 quasi-binary TMDC alloys, including some involving non-isovalent cations and are verified experimentally through the synthesis of a subset of 12 predicted alloys using a scalable chemical vapor transport method. It is demonstrated that the synthesized alloys can be exfoliated into 2D structures, and some of them exhibit: i) outstanding thermal stability tested up to 1230 K, ii) exceptionally high electrochemical activity for the CO2 reduction reaction in a kinetically limited regime with near zero overpotential for CO formation, iii) excellent energy efficiency in a high rate Li-air battery, and iv) high break-down current density for interconnect applications. This framework can be extended to accelerate the discovery of other TMDC alloys for various applications.

A Micropillar-Assisted Versatile Strategy for Highly Sensitive and Efficient Triboelectric Energy Generation under In-Plane Stimuli.

For the application of portable and wearable devices, the development of energy harvesters sensitive to various types of local and subtle mechanical displacements is essential. One of the most abundant but difficult-to-harvest mechanical energies in everyday life is the in-plane kinetic energy that arises from a rubbing motion. Here, an efficient method is proposed to generate electrical energy from tiny horizontal forces by laminating microstructures on a conventional triboelectric nanogenerator (TENG). The microhairy structures serve to induce contact friction between the two dielectric materials, driven by reversible mechanical bending when a contact rubbing pressure or noncontact airflow is applied in the horizontal direction. Compared to TENG devices without microstructures, the introduction of microstructures greatly enhances the energy harvesting in the same situation. In addition, the TENG device with micropillars can generate electrical output under tiny mechanical variations (<0.2 Pa) induced by a local deformation below individual micropillars. A high energy-generation capability is demonstrated by rubbing textured samples on the micropillar-structured TENG devices to induce horizontal contact friction. The devices can also efficiently harvest electrical energy from noncontact fluidic airflow. By assembling the microhairy structures on a conventional TENG, more complex and realistic mechanical motion can be harvested.

Serpentine-pattern effects on the biaxial stretching of percolative graphene nanoflake films.

Stretchable strain sensors based on percolative arrangements of conducting nanoparticles are essential tools in stretchable electronics and have achieved outstanding performance. Introducing serpentine patterns for strain-sensing materials is a very effective method for enhancing stretchability with a quantified structural resistance through a simple, reliable, and facile approach. Here, we investigate serpentine-pattern effects in the electrical responses to biaxial stretching for percolative graphene-nanoparticle films. Graphene nanoplatelet films are applied to a stretchable substrate using a facile spray-coating technique, for a variety of serpentine pattern shapes, aspect ratios, pattern frequencies, and number of coatings. The electrical responses after applying biaxial stretching (x-axis and y-axis) are measured and analyzed for comparison. The serpentine patterns that would be suitable for stretchable electrodes, sensitive sensors, and highly stretchable sensors are then identified. This work demonstrates the advantage of using serpentine patterns for stretchable strain sensors and offers guidelines for selecting suitable pattern types for strain sensors in stretchable-electronics applications.

Long-term balloon indwelling technique for the treatment of single benign biliary stricture.

We aimed to evaluate the feasibility and safety of long-term balloon indwelling technique for the treatment of single benign biliary stricture. Five patients with single benign biliary stricture were included from December 2014 to November 2016. The patients were three men and two women with a mean age of 50 years (range, 30-65 years). A balloon catheter was inserted into the drainage catheter and emerged through the side hole of the catheter so that the balloon and drainage catheters could be placed together at the stricture site. Follow-up fluoroscopic examination was performed at least once every 2 weeks to evaluate the adequacy of expansion and location of the balloon. The balloon was reinflated at each session, and then removed after an approximately two-month indwelling period. The catheters used were 10-16 French and the diameter of indwelling balloons were 4-8 mm. The primary technical and clinical success rates were 100%. Maintenance of the balloon location was achieved in 25 of 26 follow-up fluoroscopic examinations (mean, 5.2 times per patient) with a rate of 96.1%. The mean follow-up period after successful removal of the balloon was 542.2 days (range, 93-1042 days), and there were no recurrences in the five cases. The long-term balloon indwelling technique is a good way to induce maximal dilatation at the stricture site without large diameter skin and subcutaneous tract dilatation and can be successfully used for single benign biliary stricture.

New Class of Electrocatalysts Based on 2D Transition Metal Dichalcogenides in Ionic Liquid.

The optimization of traditional electrocatalysts has reached a point where progress is impeded by fundamental physical factors including inherent scaling relations among thermokinetic characteristics of different elementary reaction steps, non-Nernstian behavior, and electronic structure of the catalyst. This indicates that the currently utilized classes of electrocatalysts may not be adequate for future needs. This study reports on synthesis and characterization of a new class of materials based on 2D transition metal dichalcogenides including sulfides, selenides, and tellurides of group V and VI transition metals that exhibit excellent catalytic performance for both oxygen reduction and evolution reactions in an aprotic medium with Li salts. The reaction rates are much higher for these materials than previously reported catalysts for these reactions. The reasons for the high activity are found to be the metal edges with adiabatic electron transfer capability and a cocatalyst effect involving an ionic-liquid electrolyte. These new materials are expected to have high activity for other core electrocatalytic reactions and open the way for advances in energy storage and catalysis.

Atomic Structure and Electrical Activity of Grain Boundaries and Ruddlesden-Popper Faults in Cesium Lead Bromide Perovskite.

To evaluate the role of planar defects in lead-halide perovskites-cheap, versatile semiconducting materials-it is critical to examine their structure, including defects, at the atomic scale and develop a detailed understanding of their impact on electronic properties. In this study, postsynthesis nanocrystal fusion, aberration-corrected scanning transmission electron microscopy, and first-principles calculations are combined to study the nature of different planar defects formed in CsPbBr3 nanocrystals. Two types of prevalent planar defects from atomic resolution imaging are observed: previously unreported Br-rich [001](210)∑5 grain boundaries (GBs) and Ruddlesden-Popper (RP) planar faults. The first-principles calculations reveal that neither of these planar faults induce deep defect levels, but their Br-deficient counterparts do. It is found that the ∑5 GB repels electrons and attracts holes, similar to an n-p-n junction, and the RP planar defects repel both electrons and holes, similar to a semiconductor-insulator-semiconductor junction. Finally, the potential applications of these findings and their implications to understand the planar defects in organic-inorganic lead-halide perovskites that have led to solar cells with extremely high photoconversion efficiencies are discussed.

Multiferroism in Iron-Based Oxyfluoride Perovskites.

Multiferroic materials with simultaneous magnetic and ferroelectric ordering that persist above room temperature are rare. Using first-principles density functional theory calculations, we demonstrate fluorination of oxygen-deficient AA'Fe2O5 perovskites, where A and A' are cations with +3 and +2 oxidation states, respectively, and have a layered ordering, as an effective strategy to obtain room-temperature multiferroics. We show that by controlling the size of the A and A' cations, it is possible to stabilize a noncentrosymmetric phase arising due to the hybrid improper ferroelectricity mechanism, with polarization as high as 13 µC/cm2. The fluorination also stabilizes Fe in +3 oxidation state, which results in superexchange interactions that are strong enough to sustain magnetic order well above room temperature. We also show the presence of a magnetoelectric coupling wherein the switching mode that reverses the direction of the spontaneous polarization also affects the strength of the magnetic interactions. The results show that low-temperature fluorination of anion-deficient perovskites with layered cation ordering can be an effective approach to design new multiferroics.

Value of Computerized Tomography Enterography in Predicting Crohn's Disease Activity: Correlation with Crohn's Disease Activity Index and C-Reactive Protein.

BACKGROUND: The accurate evaluation of Crohn's disease activity is important for the treatment of the disease and for monitoring the response. Computerized tomography (CT) enterography is a useful imaging modality that reflects enteric inflammation, as well as extramural complications. OBJECTIVES: The aim of this study was to evaluate the correlation between CT enterographic (CTE) findings of active Crohn's disease and the Crohn's disease activity index (CDAI) and C-reactive protein (CRP). PATIENTS AND METHODS: Fifty CT enterographies of 39 patients with Crohn's disease in the small bowel were used in our study. The CDAI was assessed through clinical and laboratory variables. Multiple CT parameters, including mural hyperenhancement, mural thickness, mural stratification, comb sign, and mesenteric fat attenuation, were evaluated with a four-point scale. The presence or absence of enhanced lymph nodes, fibrofatty proliferation, sinus or fistula, abscess, and stricture were also assessed. Two gastrointestinal radiologists independently reviewed all CT images, and inter-observer agreement was examined. Correlations between CT findings, CRP, and CDAI were assessed using Spearman's rank correlation and logistic regression analysis. To assess the predictive accuracy of the model, a receiver-operating characteristic curve analysis for the sum of CT enterographic scores was used. RESULTS: Mural hyperenhancement, mural thickness, comb sign, mesenteric fat density, and fibrofatty proliferation were significantly correlated with CDAI and CRP (P < 0.05). The binary logistic regression model demonstrated that mesenteric fat density, mural stratification, and the presence of enhanced lymph nodes (P < 0.05) had an influence on CDAI severity. The area under the receiver operating characteristic curve (AUROC) of the CTE index for predicting disease activity was 0.85. Using a cut-off value of 8, the sensitivity and negative predictive values were 95% and 94%, respectively. CONCLUSION: Most CTE findings correlated with CDAI and CRP in patients with active Crohn's disease.

Genomic Characteristics of Genetic Creutzfeldt-Jakob Disease Patients with V180I Mutation and Associations with Other Neurodegenerative Disorders.

Inherited prion diseases (IPDs), including genetic Creutzfeldt-Jakob disease (gCJD), account for 10-15% of cases of prion diseases and are associated with several pathogenic mutations, including P102L, V180I, and E200K, in the prion protein gene (PRNP). The valine to isoleucine substitution at codon 180 (V180I) of PRNP is the most common pathogenic mutation causing gCJD in East Asian patients. In this study, we conducted follow-up analyses to identify candidate factors and their associations with disease onset. Whole-genome sequencing (WGS) data of five gCJD patients with V180I mutation and 145 healthy individuals were used to identify genomic differences. A total of 18,648,850 candidate variants were observed in only the patient group, 29 of them were validated as variants. Four of these validated variants were nonsense mutations, six were observed in genes directly or indirectly related to neurodegenerative disorders (NDs), such as LPA, LRRK2, and FGF20. More than half of validated variants were categorized in Gene Ontology (GO) terms of binding and/or catalytic activity. Moreover, we found differential genome variants in gCJD patients with V180I mutation, including one uniquely surviving 10 years after diagnosis of the disease. Elucidation of the relationships between gCJD and Alzheimer's disease or Parkinson's disease at the genomic level will facilitate further advances in our understanding of the specific mechanisms mediating the pathogenesis of NDs and gold standard therapies for NDs.

Band engineering in a van der Waals heterostructure using a 2D polar material and a capping layer.

Van der Waals (vdW) heterostructures are expected to play a key role in next-generation electronic and optoelectronic devices. In this study, the band alignment of a vdW heterostructure with 2D polar materials was studied using first-principles calculations. As a model case study, single-sided fluorographene (a 2D polar material) on insulating (h-BN) and metallic (graphite) substrates was investigated to understand the band alignment behavior of polar materials. Single-sided fluorographene was found to have a potential difference along the out-of-plane direction. This potential difference provided as built-in potential at the interface, which shift the band alignment between h-BN and graphite. The interface characteristics were highly dependent on the interface terminations because of this built-in potential. Interestingly, this band alignment can be modified with a capping layer of graphene or BN because the capping layer triggered electronic reconstruction near the interface. This is because the bonding nature is not covalent, but van der Waals, which made it possible to avoid Fermi-level pinning at the interface. The results of this study showed that diverse types of band alignment can be achieved using polar materials and an appropriate capping layer.

Achieving a direct band gap in oxygen functionalized-monolayer scandium carbide by applying an electric field.

In the present paper, the band gap characteristics of oxygen functionalized-monolayer scandium carbide (monolayer Sc2CO2) under a perpendicular external electric field (E-field) were studied using DFT calculations for the potential application of MXene in optoelectronic and optical nanodevices. In contrast to general pristine single-layer materials under an external E-field, monolayer Sc2CO2 undergoes an indirect to direct band gap transition under a positive E-field, and the band gap value changes sharply after the band gap transition. Remarkable variations of the band gap properties are induced by the distinct sensitivity between the Γ and K points in the lowest conduction band to the perpendicular E-field, and different types of orbital lead to the dissimilar response of each point. The present work clearly suggests an effective direction to obtain attractive band gap properties in monolayer MXene using an external E-field for next generation optoelectronic and optical devices.