Ultrafine Pt Nanoparticles on Defective Tungsten Oxide for Photocatalytic Ethylene Synthesis.

The selective conversion of ethane (C2H6) to ethylene (C2H4) under mild conditions is highly wanted, yet very challenging. Herein, it is demonstrated that a Pt/WO3-x catalyst, constructed by supporting ultrafine Pt nanoparticles on the surface of oxygen-deficient tungsten oxide (WO3-x) nanoplates, is efficient and reusable for photocatalytic C2H6 dehydrogenation to produce C2H4 with high selectivity. Specifically, under pure light irradiation, the optimized Pt/WO3-x photocatalyst exhibits C2H4 and H2 yield rates of 291.8 and 373.4 µmol g-1 h-1, respectively, coupled with a small formation of CO (85.2 µmol g-1 h-1) and CH4 (19.0 µmol g-1 h-1), corresponding to a high C2H4 selectivity of 84.9%. Experimental and theoretical studies reveal that the vacancy-rich WO3-x catalyst enables broad optical harvesting to generate charge carriers by light for working the redox reactions. Meanwhile, the Pt cocatalyst reinforces adsorption of C2H6, desorption of key reaction species, and separation and migration of light-induced charges to promote the dehydrogenation reaction with high productivity and selectivity. In situ diffuse reflectance infrared Fourier transform spectroscopy and density functional theory calculation expose the key intermediates formed on the Pt/WO3-x catalyst during the reaction, which permits the construction of the possible C2H6 dehydrogenation mechanism.

The Segmentation of Multiple Types of Uterine Lesions in Magnetic Resonance Images Using a Sequential Deep Learning Method with Image-Level Annotations.

Fully supervised medical image segmentation methods use pixel-level labels to achieve good results, but obtaining such large-scale, high-quality labels is cumbersome and time consuming. This study aimed to develop a weakly supervised model that only used image-level labels to achieve automatic segmentation of four types of uterine lesions and three types of normal tissues on magnetic resonance images. The MRI data of the patients were retrospectively collected from the database of our institution, and the T2-weighted sequence images were selected and only image-level annotations were made. The proposed two-stage model can be divided into four sequential parts: the pixel correlation module, the class re-activation map module, the inter-pixel relation network module, and the Deeplab v3 + module. The dice similarity coefficient (DSC), the Hausdorff distance (HD), and the average symmetric surface distance (ASSD) were employed to evaluate the performance of the model. The original dataset consisted of 85,730 images from 316 patients with four different types of lesions (i.e., endometrial cancer, uterine leiomyoma, endometrial polyps, and atypical hyperplasia of endometrium). A total number of 196, 57, and 63 patients were randomly selected for model training, validation, and testing. After being trained from scratch, the proposed model showed a good segmentation performance with an average DSC of 83.5%, HD of 29.3 mm, and ASSD of 8.83 mm, respectively. As far as the weakly supervised methods using only image-level labels are concerned, the performance of the proposed model is equivalent to the state-of-the-art weakly supervised methods.

Selective Electrocatalytic Conversion of Nitric Oxide to High Value-Added Chemicals.

The artificial disturbance in the nitrogen cycle has necessitated an urgent need for nitric oxide (NO) removal. Electrochemical technologies for NO conversion have gained increasing attention in recent years. This comprehensive review presents the recent advancements in selective electrocatalytic conversion of NO to high value-added chemicals, with specific emphasis on catalyst design, electrolyte composition, mass diffusion, and adsorption energies of key intermediate species. Furthermore, the review explores the synergistic electrochemical co-electrolysis of NO with specific carbon source molecules, enabling the synthesis of a range of valuable chemicals with C─N bonds. It also provides in-depth insights into the intricate reaction pathways and underlying mechanisms, offering valuable perspectives on the challenges and prospects of selective NO electrolysis. By advancing comprehension and fostering awareness of nitrogen cycle balance, this review contributes to the development of efficient and sustainable electrocatalytic systems for the selective synthesis of valuable chemicals from NO.

Atomically dispersed Ni activates adjacent Ce sites for enhanced electrocatalytic oxygen evolution activity.

Manipulating the intrinsic activity of heterogeneous catalysts at the atomic level is an effective strategy to improve the electrocatalytic performances but remains challenging. Here, atomically dispersed Ni anchored on CeO2 particles entrenched on peanut-shaped hollow nitrogen-doped carbon structures (a-Ni/CeO2@NC) is rationally designed and synthesized. The as-prepared a-Ni/CeO2@NC catalyst exhibits substantially boosted intrinsic activity and greatly reduced overpotential for the electrocatalytic oxygen evolution reaction. Experimental and theoretical results demonstrate that the decoration of isolated Ni species over the CeO2 induces electronic coupling and redistribution, thus resulting in the activation of the adjacent Ce sites around Ni atoms and greatly accelerated oxygen evolution kinetics. This work provides a promising strategy to explore the electronic regulation and intrinsic activity improvement at the atomic level, thereby improving the electrocatalytic activity.

Optimal concentration of Lugol's solution for detecting early esophageal carcinoma: A randomized controlled trial.

BACKGROUND AND AIM: Lugol chromoendoscopy is the standard technique to detect an esophageal squamous cell carcinoma (ESCC). However, a high concentration of Lugol's solution can induce mucosal injury and adverse events. We aimed to investigate the optimal concentration of Lugol's solution to reduce mucosal injury and adverse events without degrading image quality. METHODS: This was a two-phase double-blind randomized controlled trial. In phase I, 200 eligible patients underwent esophagogastroduodenoscopy and then were randomly (1:1:1:1:1) sprayed with 1.2%, 1.0%, 0.8%, 0.6%, or 0.4% Lugol's solution. Image quality, gastric mucosal injury, adverse events, and operation satisfaction were compared to investigate the minimal effective concentration. In phase II, 42 cases of endoscopic mucosectomy for early ESCC were included. The patients were randomly assigned (1:1) to the minimal effective (0.6%) or conventional (1.2%) concentration of Lugol's solution for further comparison of the effectiveness. RESULTS: In phase I, the gastric mucosal injury was significantly reduced in 0.6% group (P < 0.05). Furthermore, there was no statistical significance in image quality between 0.6% and higher concentrations of Lugol's solution (P > 0.05, respectively). It also showed that the operation satisfaction decreased in 1.2% group compared with the lower concentration groups (P < 0.05). In phase II, the complete resection rate was 100% in both groups, while 0.6% Lugol's solution showed higher operation satisfaction (W = 554.500, P = 0.005). CONCLUSIONS: The study indicates that 0.6% might be the optimal concentration of Lugol's solution for early detection and delineation of ESCC, considering minimal mucosal injury and satisfied image. The registry of clinical trials: ClinicalTrials.gov (NCT03180944).

Supporting Trimetallic Metal-Organic Frameworks on S/N-Doped Carbon Macroporous Fibers for Highly Efficient Electrocatalytic Oxygen Evolution.

Hybrid materials, integrating the merits of individual components, are ideal structures for efficient oxygen evolution reaction (OER). However, the rational construction of hybrid structures with decent physical/electrochemical properties is yet challenging. Herein, a promising OER electrocatalyst composed of trimetallic metal-organic frameworks supported over S/N-doped carbon macroporous fibers (S/N-CMF@Fex Coy Ni1-x-y -MOF) via a cation-exchange strategy is delicately fabricated. Benefiting from the trimetallic composition with improved intrinsic activity, hollow S/N-CMF matrix facilitating exposure of active sites, as well as their robust integration, the resultant S/N-CMF@Fex Coy Ni1-x-y -MOF electrocatalyst delivers outstanding activity and stability for alkaline OER. Specifically, it needs an overpotential of 296 mV to reach the benchmark current density of 10 mA cm-2 with a small Tafel slope of 53.5 mV dec-1 . In combination with X-ray absorption fine structure spectroscopy and density functional theory calculations, the post-formed Fe/Co-doped γ-NiOOH during the OER operation is revealed to account for the high OER performance of S/N-CMF@Fex Coy Ni1-x-y -MOF.

Surface-Exposed Single-Ni Atoms with Potential-Driven Dynamic Behaviors for Highly Efficient Electrocatalytic Oxygen Evolution.

Trapping the active sites on the exterior surface of hollow supports can reduce mass transfer resistance and enhance atomic utilization. Herein, we report a facile chemical vapor deposition strategy to synthesize single-Ni atoms decorated hollow S/N-doped football-like carbon spheres (Ni SAs@S/N-FCS). Specifically, the CdS@3-aminophenol/formaldehyde is carbonized into S/N-FCS. The gas-migrated Ni species are anchored on the surface of S/N-FCS simultaneously, yielding Ni SAs@S/N-FCS. The obtained catalyst exhibits outstanding performance for alkaline oxygen evolution reaction (OER) with an overpotential of 249 mV at 10 mA cm-2 , a small Tafel slope of 56.5 mV dec-1 , and ultra-long stability up to 166 hours without obvious fading. Moreover, the potential-driven dynamic behaviors of Ni-N4 sites and the contribution of the S dopant at different locations in the matrix to the OER activity are revealed by the operando X-ray absorption spectroscopy and theoretical calculations, respectively.

Exposing Single Ni Atoms in Hollow S/N-Doped Carbon Macroporous Fibers for Highly Efficient Electrochemical Oxygen Evolution.

The development of efficient and cost-effective electrocatalysts toward the oxygen evolution reaction (OER) is highly desirable for clean energy and fuel conversion. Herein, the facile preparation of Ni single atoms embedded hollow S/N-doped carbon macroporous fibers (Ni SAs@S/N-CMF) as efficient catalysts for OER through pyrolysis of designed CdS-NiSx /polyacrylonitrile composite fibers is reported. Specifically, CdS provides the sulfur source for the doping of polyacrylonitrile-derived carbon matrix and simultaneously creates the hollow macroporous structure, while NiSx is first reduced to nanoparticles and finally evolves into single Ni atoms through the atom migration-trapping strategy. Benefiting from the abundantly exposed single Ni atoms and hollow macroporous structure, the resultant Ni SAs@S/N-CMF electrocatalysts deliver outstanding activity and stability for OER. Specifically, it needs an overpotential of 285 mV to achieve the benchmark current density of 10 mA cm-2 with a small Tafel slope of 50.8 mV dec-1 .

Highly Efficient Electrocatalytic Oxygen Evolution Over Atomically Dispersed Synergistic Ni/Co Dual Sites.

Single-atom catalysts (SACs) are being pursued as economical electrocatalysts. However, their low active-site loading, poor interactions, and unclear catalytic mechanism call for significant advances. Herein, atomically dispersed Ni/Co dual sites anchored on nitrogen-doped carbon (a-NiCo/NC) hollow prisms are rationally designed and synthesized. Benefiting from the atomically dispersed dual-metal sites and their synergistic interactions, the obtained a-NiCo/NC sample exhibits superior electrocatalytic activity and kinetics towards the oxygen evolution reaction. Moreover, density functional theory calculations indicate that the strong synergistic interactions from heteronuclear paired Ni/Co dual sites lead to the optimization of the electronic structure and the reduced reaction energy barrier. This work provides a promising strategy for the synthesis of high-efficiency atomically dispersed dual-site SACs in the field of electrochemical energy storage and conversion.

Synthesis of N-Doped Highly Graphitic Carbon Urchin-Like Hollow Structures Loaded with Single-Ni Atoms towards Efficient CO2 Electroreduction.

The rational design of single-atom catalysts featuring excellent conductivity, highly accessible discrete active sites and favorable mass transfer is crucial for electrocatalysis but remains challenging. In this study, a reliable Ni-catalyzed and Ni-templated strategy is developed to synthesize a single-atom catalyst by transforming metallic Ni into single-Ni atoms anchored on hollow porous urchin-like (HPU) N-doped carbon (NC) (designated as Ni-NC(HPU)), which possesses high crystallinity and sufficient Ni-N4 moiety (2.4 wt %). The unique hollow thorns on the surface, good conductivity and large external surface area facilitate electron/mass transfer and exposure of single-Ni sites. As a result, the Ni-NC(HPU) catalyst exhibits remarkable activity and high stability for CO2 electroreduction. Moreover, this synthetic strategy can also be facilely extended to prepare distinct hollow porous architectures with similar components, such as the wire- and sphere-like ones.

Prediction of high-risk esophageal varices in patients with chronic liver disease with point and 2D shear wave elastography: a systematic review and meta-analysis.

OBJECTIVE: To assess the diagnostic performance of liver stiffness (LS) and spleen stiffness (SS) measured by point shear wave elastography (pSWE) and 2D shear wave elastography (2D-SWE) in the detection of high-risk esophageal varices (HREV) and to compare their diagnostic accuracy. METHODS: Through systematic search of PubMed, Embase, and Web of Science databases, we included 17 articles reporting the diagnostic performance of LS or SS measured by pSWE or 2D-SWE for HREV. We used a bivariate random-effects model to estimate pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), area under summary receiver operator characteristic curve (AUSROC), and diagnostic odds ratio (DOR). RESULTS: For LS, there was no significant difference between the pooled sensitivity, 0.89 (95% confidence interval CI, 0.81-0.94) vs. 0.8 (95% CI, 0.72-0.86) (p = 0.13), and specificity, 0.81 (95% CI, 0.73-0.87) vs. 0.73 (95% CI, 0.65-0.79) (p = 0.07) of pSWE and 2D-SWE. The AUSROC and DOR of pSWE were higher than those of 2D-SWE: 0.92 (95% CI, 0.89-0.94) vs. 0.84 (95% CI, 0.80-0.87), p = 0.03, 33 (95% CI, 25-61) vs. 11 (95% CI, 5-22), (p < 0.01). For SS, there was no significant difference between the pooled sensitivity 0.91 (95% CI, 0.78-0.96) vs. 0.89 (95% CI, 0.80-0.94) (p = 0.43); specificity, 0.79 (95% CI, 0.72-0.84) vs. 0.72 (95% CI, 0.63-0.79) (p = 0.06); and DOR, 35 (95% CI, 13-100) vs. 20 (95% CI, 8-50) (p = 0.16) of pSWE and 2D-SWE. CONCLUSION: LS and SS measured by pSWE and 2D-SWE have good accuracy in predicting HREV. KEY POINTS: • There is modest difference between the diagnostic performance of LS and SS measured by pSWE and 2D-SWE. • LS and SS measured by pSWE and 2D-SWE both have high sensitivity, specificity, and AUSROC for the evaluation of HREV in patients with CLD. • pSWE and 2D-SWE are promising tools for noninvasive monitoring risk of esophageal varices bleeding of CLD patients.

Phosphorized CoNi2 S4 Yolk-Shell Spheres for Highly Efficient Hydrogen Production via Water and Urea Electrolysis.

Exploring earth-abundant electrocatalysts with excellent activity, robust stability, and multiple functions is crucial for electrolytic hydrogen generation. Porous phosphorized CoNi2 S4 yolk-shell spheres (P-CoNi2 S4 YSSs) were rationally designed and synthesized by a combined hydrothermal sulfidation and gas-phase phosphorization strategy. Benefiting from the strengthened Ni3+ /Ni2+ couple, enhanced electronic conductivity, and hollow structure, the P-CoNi2 S4 YSSs exhibit excellent activity and durability towards hydrogen/oxygen evolution and urea oxidation reactions in alkaline solution, affording low potentials of -0.135 V, 1.512 V, and 1.306 V (versus reversible hydrogen electrode) at 10 mA cm-2 , respectively. Remarkably, when used as the anode and cathode simultaneously, the P-CoNi2 S4 catalyst merely requires a cell voltage of 1.544 V in water splitting and 1.402 V in urea electrolysis to attain 10 mA cm-2 with excellent durability for 100 h, outperforming most of the reported nickel-based sulfides and even noble-metal-based electrocatalysts. This work promotes the application of sulfides in electrochemical hydrogen production and provides a feasible approach for urea-rich wastewater treatment.

Construction of Co-Mn Prussian Blue Analog Hollow Spheres for Efficient Aqueous Zn-ion Batteries.

Prussian blue analogs (PBAs) are considered as reliable and promising cathode materials for aqueous Zn-ion batteries (AZIBs), but they suffer from low capacity and poor cycling stability due to insufficient active sites and structural damage caused by the ion insertion/extraction processes. Herein, a template-engaged ion exchange approach has been developed for the synthesis of Co-substituted Mn-rich PBA hollow spheres (CoMn-PBA HSs) as cathode materials for AZIBs. Benefiting from the multiple advantageous features including hollow structure, abundant active sites, fast Zn2+ ion diffusion, and partial Co substitution, the CoMn-PBA HSs electrode shows efficient zinc ion storage properties in terms of high capacity, decent rate capability and prolonged cycle life.

Engineering Platinum-Cobalt Nano-alloys in Porous Nitrogen-Doped Carbon Nanotubes for Highly Efficient Electrocatalytic Hydrogen Evolution.

Highly efficient electrocatalysts are essential for the production of green hydrogen from water electrolysis. Herein, a metal-organic framework-assisted pyrolysis-replacement-reorganization approach is developed to obtain ultrafine Pt-Co alloy nanoparticles (sub-10 nm) attached on the inner and outer shells of porous nitrogen-doped carbon nanotubes (NCNT) with closed ends. During the thermal reorganization, the migration of Pt-Co nano-alloys to both surfaces ensures the maximized exposure of active sites while maintaining the robust attachment to the porous carbon matrix. Density functional theory calculations suggest a nearly thermodynamically-neutral free energy of adsorption for hydrogen intermediates and diversified active sites induced by alloying, thus resulting in a great promotion in intrinsic activity towards the hydrogen evolution reaction (HER). Benefiting from the delicate structural design and compositional modulation, the optimized Pt3 Co@NCNT electrocatalyst manifests outstanding HER activity and superior stability in both acidic and alkaline media.

Trimetallic Spinel NiCo2-x Fex O4 Nanoboxes for Highly Efficient Electrocatalytic Oxygen Evolution.

The development of efficient and low-cost electrocatalysts toward the oxygen evolution reaction (OER) is critical for improving the efficiency of several electrochemical energy conversion and storage devices. Here, we report an elaborate design and synthesis of porous Co-based trimetallic spinel oxide nanoboxes (NiCo2-x Fex O4 NBs) by a novel metal-organic framework engaged strategy, which involves chemical etching, cation exchange, and subsequent thermal oxidation processes. Owing to the structural and compositional advantages, the optimized trimetallic NiCo2-x Fex O4 NBs (x is about 0.117) deliver superior electrocatalytic performance for OER with an overpotential of 274 mV at 10 mA cm-2 , a small Tafel slope of 42 mV dec-1 , and good stability in alkaline electrolyte, which is much better than that of Co-based bi/monometallic spinel oxides and even commercial RuO2 .

Metal-Organic Frameworks Derived Functional Materials for Electrochemical Energy Storage and Conversion: A Mini Review.

With many apparent advantages including high surface area, tunable pore sizes and topologies, and diverse periodic organic-inorganic ingredients, metal-organic frameworks (MOFs) have been identified as versatile precursors or sacrificial templates for preparing functional materials as advanced electrodes or high-efficiency catalysts for electrochemical energy storage and conversion (EESC). In this Mini Review, we first briefly summarize the material design strategies to show the rich possibilities of the chemical compositions and physical structures of MOFs derivatives. We next highlight the latest advances focusing on the composition/structure/performance relationship and discuss their practical applications in various EESC systems, such as supercapacitors, rechargeable batteries, fuel cells, water electrolyzers, and carbon dioxide/nitrogen reduction reactions. Finally, we provide some of our own insights into the major challenges and prospective solutions of MOF-derived functional materials for EESC, hoping to shed some light on the future development of this highly exciting field.

Nitrogen-Doped Amorphous Zn-Carbon Multichannel Fibers for Stable Lithium Metal Anodes.

The application of lithium metal anodes for practical batteries is still impeded by safety issues and low Coulombic efficiency caused mainly by the uncontrollable growth of lithium dendrites. Herein, two types of free-standing nitrogen-doped amorphous Zn-carbon multichannel fibers are synthesized as multifunctional hosts for lithium accommodation. The 3D macroporous structures endow effectively reduced local current density, and the lithiophilic nitrogen-doped carbon and functional Zn nanoparticles serve as preferred deposition sites with low nucleation barriers to guide uniform lithium deposition. As a result, the developed anodes exhibit remarkable electrochemical properties in terms of high Coulombic efficiency for more than 500 cycles at various current densities from 1 to 5 mA cm-2 , and symmetric cells show long-term cycling duration over 2000 h. Moreover, full cells based on the developed anode and a LiFePO4 cathode also demonstrate superior rate capability and stable cycle life.

Nitrogen-Doped Cobalt Pyrite Yolk-Shell Hollow Spheres for Long-Life Rechargeable Zn-Air Batteries.

Limited by the sluggish four-electron transfer process, designing high-performance nonprecious electrocatalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is urgently desired for efficient rechargeable Zn-air batteries (ZABs). Herein, the successful synthesis of porous nitrogen-doped cobalt pyrite yolk-shell nanospheres (N-CoS2 YSSs) is reported. Benefiting from the abundant porosity of the porous yolk-shell structure and unique electronic properties by nitrogen doping, the as-prepared N-CoS2 YSSs possess more exposed active surface, thus giving rise to superior activity for reversible oxygen electrocatalysis and outstanding cycling stability (more than 165 h at 10 mA cm-2) in ZABs, exceeding the commercial Pt/C and RuO2 hybrid catalysts. Moreover, the assembled ZABs, delivering a specific capacity of 640 mAh gZn -1, can be used for practical devices. This work provides a novel tactic to engineer sulfides as high efficiency and promising bifunctional oxygen electrocatalysts for advanced metal-air batteries.

Emerging Multifunctional Single-Atom Catalysts/Nanozymes.

Single-atom catalysts (SACs), in which the metal active sites are isolated on the support and stabilized by coordinated atoms such as oxygen, nitrogen, sulfur, etc., represent the maximum usage efficiency of the metal atoms. Benefiting from the recent progress in synthetic strategies, characterization methods, and computational models, many SACs that deliver an impressive catalytic performance for a variety of reactions have been developed. The catalytic selectivity and activity are critical issues that need to be optimized and augmented in the areas of nanotechnology and biomedicine. This review summarizes some recent experimental and theoretical progress aimed at clarifying the structure of SACs and how they influence the catalytic performance. The examples described here elaborate on the utility of SACs and highlight the strengths of these catalysts in the applications of biomedicine, environmental protection, and energy conversion. Finally, some current challenges and future perspectives for SACs are also discussed.

Co3 O4 Hollow Nanoparticles Embedded in Mesoporous Walls of Carbon Nanoboxes for Efficient Lithium Storage.

Confining nanostructured electrode materials in porous carbon represents an effective strategy for improving the electrochemical performance of lithium-ion batteries. Herein, we report the design and synthesis of hybrid hollow nanostructures composed of highly dispersed Co3 O4 hollow nanoparticles (sub-20 nm) embedded in the mesoporous walls of carbon nanoboxes (denoted as H-Co3 O4 @MCNBs) as an anode material for lithium-ion batteries. The facile metal-organic framework (MOF)-engaged strategy for the synthesis of H-Co3 O4 @MCNBs involves chemical etching-coordination and subsequent two-step annealing treatments. Owing to the unique structural merits including more active interfacial sites, effectively alleviated volume variation, good and stable electrical contact, and easy access of Li+ ions, the H-Co3 O4 @MCNBs exhibit excellent lithium-storage performance in terms of high specific capacity, excellent rate capability, and cycling stability.