Pivotal role of reversible NiO6 geometric conversion in oxygen evolution.

Realizing an efficient electron transfer process in the oxygen evolution reaction by modifying the electronic states around the Fermi level is crucial in developing high-performing and robust electrocatalysts1-3. Typically, electron transfer proceeds solely through either a metal redox chemistry (an adsorbate evolution mechanism (AEM), with metal bands around the Fermi level) or an oxygen redox chemistry (a lattice oxygen oxidation mechanism (LOM), with oxygen bands around the Fermi level), without the concurrent occurrence of both metal and oxygen redox chemistries in the same electron transfer pathway1-15. Here we report an electron transfer mechanism that involves a switchable metal and oxygen redox chemistry in nickel-oxyhydroxide-based materials with light as the trigger. In contrast to the traditional AEM and LOM, the proposed light-triggered coupled oxygen evolution mechanism requires the unit cell to undergo reversible geometric conversion between octahedron (NiO6) and square planar (NiO4) to achieve electronic states (around the Fermi level) with alternative metal and oxygen characters throughout the oxygen evolution process. Utilizing this electron transfer pathway can bypass the potential limiting steps, that is, oxygen-oxygen bonding in AEM and deprotonation in LOM1-5,8. As a result, the electrocatalysts that operate through this route show superior activity compared with previously reported electrocatalysts. Thus, it is expected that the proposed light-triggered coupled oxygen evolution mechanism adds a layer of understanding to the oxygen evolution research scene.

Electrochemical Knocking-Down of Zn Metal Clusters into Single Atoms.

Single Atoms Catalysts (SACs) have emerged as a class of highly promising heterogeneous catalysts, where the traditional bottom-up synthesis approaches often encounter considerable challenges in relation to aggregation issues and poor stability. Consequently, achieving densely dispersed atomic species in a reliable and efficient manner remains a key focus in the field. Herein, we report a new facile electrochemical knock-down strategy for the formation of SACs, whereby the metal Zn clusters are transformed into single atoms. While a defect-rich substrate plays a pivotal role in capturing and stabilizing isolated Zn atoms, the feasibility of this novel strategy is demonstrated through a comprehensive investigation, combining experimental and theoretical studies. Furthermore, when studied in exploring for potential applications, the material prepared shows a remarkable improvement of 58.21% for the Li+ storage and delivers a capacity over 300 Wh kg-1 after 500 cycles upon the transformation of Zn clusters into single atoms.

Frameworked Electrolytes: A Pathway Towards Solid Future of Batteries.

All-solid-state batteries (ASSBs) represent a highly promising next-generation energy storage technology owing to their inherently high safety, device reliability, and potential for achieving high energy density in the post-ara of lithium-ion batteries, and therefore extensive searches are ongoing for ideal solid-state electrolytes (SSEs). Though promising, there is still a huge barrier that limits the large-scale applications of ASSBs, where there are a couple of bottleneck technical issues. In this perspective, a novel category of electrolytes known as frameworked electrolytes (FEs) are examined, where the solid frameworks are intentionally designed to contain 3D ionic channels at sub-nano scales, rendering them macroscopically solid. The distinctive structural design of FEs gives rise to not only high ionic conductivity but also desirable interfaces with electrode solids. This is achieved through the presence of sub-nano channels within the framework, which exhibit significantly different ion diffusion behavior due to the confinement effect. This perspective offers a compelling insight into the potential of FEs in the pursuit of ASSBs, where FEs offer an exciting opportunity to overcome the limitations of traditional solid-state electrolytes and propel the development of ASSBs as the holy grail of energy storage technology.

Ultrathin LayCoOx Nanosheets with High Porosity Featuring Boosted Catalytic Oxidation of Benzene: Mechanism Elucidation via an Experiment-Theory Combined Paradigm.

Designing transition-metal oxides for catalytically removing the highly toxic benzene holds significance in addressing indoor/outdoor environmental pollution issues. Herein, we successfully synthesized ultrathin LayCoOx nanosheets (thickness of ∼1.8 nm) with high porosity, using a straightforward coprecipitation method. Comprehensive characterization techniques were employed to analyze the synthesized LayCoOx catalysts, revealing their low crystallinity, high surface area, and abundant porosity. Catalytic benzene oxidation tests demonstrated that the La0.029CoOx-300 nanosheet exhibited the most optimal performance. This catalyst enabled complete benzene degradation at a relatively low temperature of 220 °C, even under a high space velocity (SV) of 20,000 h-1, and displayed remarkable durability throughout various catalytic assessments, including SV variations, exposure to water vapor, recycling, and long time-on-stream tests. Characterization analyses confirmed the enhanced interactions between Co and doped La, the presence of abundant adsorbed oxygen, and the extensive exposure of Co3+ species in La0.029CoOx-300 nanosheets. Theoretical calculations further revealed that La doping was beneficial for the formation of oxygen vacancies and the adsorption of more hydroxyl groups. These features strongly promoted the adsorption and activation of oxygen, thereby accelerating the benzene oxidation processes. This work underscores the advantages of doping rare-earth elements into transition-metal oxides as a cost-effective yet efficient strategy for purifying industrial exhausts.

General Entropy Approach Toward Ultratough Sustainable Plastics.

Entropy is a universal concept across the physics of mixtures. While the role of entropy in other multicomponent materials has been appreciated, its effects in polymers and plastics have not. In this work, it is demonstrated that the seemingly small mixing entropy contributes to the miscibility and performance of polymer alloys. Experimental and modeling studies on over 30 polymer pairs reveal a strong correlation between entropy, morphology, and mechanical properties, while elucidating the mechanism behind: in polymer blends with weak interactions, entropy leads to homogeneously dispersed nanosized domains stabilized by highly entangled chains. This unique microstructure promotes uniform plastic deformation at the interface, thus improving the toughness of conventional brittle polymers by 1-2 orders of magnitude without sacrificing other properties, analogous to high-entropy metallic alloys. The proposed strategy also applies to ternary polymer systems and copolymers, offering a new pathway toward the development of sustainable polymers.

Outcome and Risk of Poststroke Pneumonia in Patients with Acute Ischemic Stroke After Endovascular Thrombectomy: A Post Hoc Analysis of the DIRECT-MT Trial.

BACKGROUND: In this study, we aimed to investigate the risk factors and impact of poststroke pneumonia (PSP) on mortality and functional outcome in patients with acute ischemic stroke (AIS) after endovascular thrombectomy (EVT). METHODS: This was a post hoc analysis of a prospective randomized trial (Direct intraarterial thrombectomy in order to revascularize AIS patients with large-vessel occlusion efficiently in Chinese tertiary hospitals: a multicenter randomized clinical trial). Patients with AIS who completed EVT were evaluated for the occurrence of PSP during the hospitalization period and their modified Rankin Scale (mRS) scores at 90 days after AIS. Logistic regression analysis was conducted to investigate the independent predictors of PSP. Propensity score matching was conducted for the PSP and non-PSP groups by using the covariates resulting from the logistic regression analysis. The associations between PSP and outcomes were analyzed. The outcomes included 90-day poor functional outcome (mRS scores > 2), 90-day mortality, and early 2-week mortality. RESULTS: A total of 639 patients were enrolled, of whom 29.58% (189) developed PSP. Logistic regression analysis revealed that history of chronic heart failure (unadjusted odds ratio [OR] 2.011, 95% confidence interval [CI] 1.026-3.941; P = 0.042), prethrombectomy reperfusion on initial digital subtraction angiography (OR 0.394, 95% CI 0.161-0.964; P = 0.041), creatinine levels at admission (OR 1.008, 95% CI 1.000-1.016; P = 0.049), and National Institutes of Health Stroke Scale at 24 h (OR 1.023, 95% CI 1.007-1.039; P = 0.004) were independent risk factors for PSP. With propensity scoring matching, poor functional outcome (mRS > 2) was more common in patients with PSP than in patients without PSP (81.03% vs. 71.83%, P = 0.043) at 90 days after EVT. The early 2-week mortality of patients with PSP was lower (5.74% vs. 12.07%, P = 0.038). But there was no statistically significant difference in 90-day mortality between the PSP group and non-PSP group (22.41% vs. 14.94%, P = 0.074). The survivorship curve also shows no statistical significance (P = 0.088) between the two groups. CONCLUSIONS: Nearly one third of patients with AIS and EVT developed PSP. Heart failure, higher creatinine levels, prethrombectomy reperfusion, and National Institutes of Health Stroke Scale at 24 h were associated with PSP in these patients. PSP was associated with poor 90-day functional outcomes in patients with AIS treated with EVT.

Hydroxyl-Decorated Pt as a Robust Water-Resistant Catalyst for Catalytic Benzene Oxidation.

In catalytic oxidation reactions, the presence of environmental water poses challenges to the performance of Pt catalysts. This study aims to overcome this challenge by introducing hydroxyl groups onto the surface of Pt catalysts using the pyrolysis reduction method. Two silica supports were employed to investigate the impact of hydroxyl groups: SiO2-OH with hydroxyl groups and SiO2-C without hydroxyl groups. Structural characterization confirmed the presence of Pt-Ox, Pt-OHx, and Pt0 species in the Pt/SiO2-OH catalysts, while only Pt-Ox and Pt0 species were observed in the Pt/SiO2-C catalysts. Catalytic performance tests demonstrated the remarkable capacity of the 0.5 wt % Pt/SiO2-OH catalyst, achieving complete conversion of benzene at 160 °C under a high space velocity of 60,000 h-1. Notably, the catalytic oxidation capacity of the Pt/SiO2-OH catalyst remained largely unaffected even in the presence of 10 vol % water vapor. Moreover, the catalyst exhibited exceptional recyclability and stability, maintaining its performance over 16 repeated cycles and a continuous operation time of 70 h. Theoretical calculations revealed that the construction of Pt-OHx sites on the catalyst surface was beneficial for modulating the d-band structure, which in turn enhanced the adsorption and activation of reactants. This finding highlights the efficacy of decorating the Pt surface with hydroxyl groups as an effective strategy for improving the water resistance, catalytic activity, and long-term stability of Pt catalysts.

Microstructure-driven mechanical and electromechanical phenomena in additively manufactured nanocrystalline zinc oxide.

Advances in nanoscale additive manufacturing (AM) offer great opportunities to expand nanotechnologies; however, the size effects in these printed remain largely unexplored. Using bothin situnanomechanical and electrical experiments and molecular dynamics (MD) simulations, this study investigates additively manufactured nano-architected nanocrystalline ZnO (nc-ZnO) with ∼7 nm grains and dimensions spanning 0.25-4µm. These nano-scale ceramics are fabricated through printing and subsequent burning of metal ion-containing hydrogels to produce oxide structures. Electromechanical behavior is shown to result from random ordering in the microstructure and can be modeled through a statistical treatment. A size effect in the failure behavior of AM nc-ZnO is also observed and characterized by the changes in deformation behavior and suppression of brittle failure. MD simulations provide insights to the role of grain boundaries and grain boundary plasticity on both electromechanical behavior and failure mechanisms in nc-ZnO. The frameworks developed in this paper extend to other AM nanocrystalline materials and provide quantification of microstructurally-drive limitations to precision in materials property design.

Extraordinary Strain Hardening from Dislocation Loops in Defect-Free Al Nanocubes.

The complex interaction of crystalline defects leads to strain hardening in bulk metals. Metals with high stacking fault energy (SFE), such as aluminum, tend to have low strain hardening rates due to an inability to form stacking faults and deformation twins. Here, we use in situ scanning electron microscopy (SEM) mechanical compressions to find that colloidally synthesized defect-free 114 nm Al nanocubes combine a high linear strain hardening rate of 4.1 GPa with a high strength of 1.1 GPa. These nanocubes have a 3 nm self-passivating oxide layer that has a large influence on mechanical behavior and the accumulation of dislocation structures. Postcompression transmission electron microcopy (TEM) imaging reveals stable prismatic dislocation loops and the absence of stacking faults. MD simulations relate the formation of dislocation loops and strain hardening to the surface oxide. These results indicate that slight modifications to surface and interfacial properties can induce enormous changes to mechanical properties in high SFE metals.

Achieving Boron-Carbon-Nitrogen Heterostructures by Collision Fusion of Carbon Nanotubes and Boron Nitride Nanotubes.

Heterostructures may exhibit completely new physical properties that may be otherwise absent in their individual component materials. However, how to precisely grow or assemble desired complex heterostructures is still a significant challenge. In this work, the collision dynamics of a carbon nanotube and a boron nitride nanotube under different collision modes were investigated using the self-consistent-charge density-functional tight-binding molecular dynamics method. The energetic stability and electronic structures of the heterostructure after collision were calculated using the first-principles calculations. Five main collision outcomes are observed, that is, two nanotubes can (1) bounce back, (2) connect, (3) fuse into a defect-free BCN heteronanotube with a larger diameter, (4) form a heteronanoribbon of graphene and hexagonal boron nitride and (5) create serious damage after collision. It was found that both the BCN single-wall nanotube and the heteronanoribbon created by collision are the direct band-gap semiconductors with the band gaps of 0.808 eV and 0.544 eV, respectively. These results indicate that collision fusion is a viable method to create various complex heterostructures with new physical properties.

Sumanene Monolayer of Pure Carbon: A Two-Dimensional Kagome-Analogy Lattice with Desirable Band Gap, Ultrahigh Carrier Mobility, and Strong Exciton Binding Energy.

The design and synthesis of novel two-dimensional (2D) materials that possess robust structural stability and unusual physical properties may open up enormous opportunities for device and engineering applications. Herein, a 2D sumanene lattice that can be regarded as a derivative of the conventional Kagome lattice is proposed. The tight-binding analysis demonstrates sumanene lattice contains two sets of Dirac cones and two sets of flat bands near the Fermi surface, distinctively different from the Kagome lattice. Using first-principles calculations, two possible routines for the realization of stable 2D sumanene monolayers (named α phase and ß phase) are theoretically suggested, and an α-sumanene monolayer can be experimentally synthesized with chemical vapor deposition using C21 H12 as a precursor. Small binding energies on Au(111) surface (e.g., -37.86 eV Å-2 for α phase) signify the possibility of their peel-off after growing on the noble metal substrate. Importantly, the GW plus Bethe-Salpeter equation calculations demonstrate both monolayers have moderate band gaps (1.94 eV for α) and ultrahigh carrier mobilities (3.4 × 104 cm2  V-1  s-1 for α). In particular, the α-sumanene monolayer possesses a strong exciton binding energy of 0.73 eV, suggesting potential applications in optics.

Effect of baseline infarct size on endovascular thrombectomy with or without intravenous alteplase in stroke patients: A subgroup analysis of a randomized trial (DIRECT-MT).

BACKGROUND AND PURPOSE: DIRECT-MT showed that endovascular thrombectomy was noninferior to thrombectomy preceded by intravenous alteplase with regard to functional outcome in patients with acute ischemic stroke. In this post hoc analysis, we examined whether infarct size modified the effect of alteplase. METHODS: All patients with baseline Alberta Stroke Program Early Computed Tomography Score (ASPECTS) grades were included. The primary outcome was the 90-day modified Rankin Scale (mRS) score. Multivariate ordinal logistic regression analysis was used to calculate the adjusted common odds ratio (OR) for better functional outcome based on the mRS for thrombectomy alone versus combination therapy. An interaction term was entered to test for an interaction with baseline ASPECTS subgroups: 0-4 versus 5-7 versus 8-10. RESULTS: Of 649 patients, 323 (49.8%) were in the thrombectomy-alone group and 326 (50.2%) in the combination-therapy group. There was no significant treatment-by-trichotomized ASPECTS interaction with alteplase prior to endovascular treatment for the primary endpoint of ordinal mRS (p-value interaction term relative to ASPECTS 8-10: ASPECTS 0-4, p = 0.386; ASPECTS 5-7, p = 0.936). Adjusted common ORs for improvement in the 90-day mRS with thrombectomy alone compared with combination therapy were 1.99 (95% confidence interval = 0.72-5.46) for ASPECTS 0-4, 1.07 (0.62-1.86) for ASPECTS 5-7, and 1.03 (0.74-1.45) for ASPECTS 8-10. There was no significant difference in the safety outcomes between the two groups. CONCLUSIONS: Baseline infarct size may not modify the effect of alteplase prior to endovascular thrombectomy with regard to favorable functional outcomes and adverse events.

Universal Zigzag Edge Reconstruction of an α-Phase Puckered Monolayer and Its Resulting Robust Spatial Charge Separation.

Edges are important, because they dictate the stability and properties of nanoribbons. Here, we reveal a universal reconstruction of the ZZ edge into a (2 × 1) tubed [ZZ(Tube)] edge, enabling an ultimate narrow nanotube to terminate nanoribbons for α-puckered group-V elemental and compound monolayers (GeS/Se and SnS/Se). The reconstructed edge formations are confirmed by CALYPSO. The ZZ(Tube) edge forms easily, is highly stable, and is semiconducting. Remarkably, the ZZ(Tube) edge always exhibits a type-II band structure and robust spatial charge separation. For a compound monolayer monochalcogenide, mild (2 × 1) ZZ(S-R) occurs at the chalcogenide-terminated edge. TDDFT simulations indicate that charge separation occurs only at 672 fs, while the lifetime is over 5 ns, thus facilitating robust spatial charge accumulation. These remarkable features of ZZ(Tube) edge-terminated α-puckered nanoribbons are ideal for optoelectronic and photocatalytic applications.

Overcoming malignant cell-based mechanisms of resistance to immune checkpoint blockade antibodies.

Traditional cancer treatment approaches have focused on surgery, radiation therapy, and cytotoxic chemotherapy. However, with rare exceptions, metastatic cancers were considered to be incurable by traditional therapy. Over the past 20 years a fourth modality - immunotherapy - has emerged as a potentially curative approach for patients with advanced metastatic cancer. However, in many patients cancer "finds a way" to evade the anti-tumor effects of immunotherapy. Immunotherapy resistance mechanisms can be employed by both cancer cells and the non-cancer elements of tumor microenvironment. This review focuses on the resistance mechanisms that are specifically mediated by cancer cells. In order to extend the impact of immunotherapy to more patients and across all cancer types, and to inhibit the development of acquired resistance, the underlying biology driving immune escape needs to be better understood. Elucidating mechanisms of immune escape may shed light on new therapeutic targets, and lead to successful combination therapeutic strategies.

Rapid Estimation of Binding Constants for Cucurbit[8]uril Ternary Complexes Using Electrochemistry.

Supramolecular complexes are of fundamental interests in biomedicines and adaptive materials, and thus facile methods to determine their binding affinity show usefulness in the design of novel drugs and materials. Herein, we report a novel approach to estimate the binding constants KG2 of cucurbit[8]uril-methyl viologen-based ternary complexes (CB8-MV2+-G2) using electrochemistry, achieving high precision (±0.03) and practical accuracy (±0.32) in logKG2 and short measurement time (<10 min). In particular, we have uncovered a linear correlation (R2 > 0.8) between the reduction potential of CB8-MV2+-G2 ternary complexes and their reported binding constants from isothermal titration calorimetry, which allow a calibration curve to be plotted based on 25 sample complexes. Mechanistic investigation using experimental and computational approaches reveals that this correlation stems from the dynamic host-guest exchange events occurring after the electron transfer step. Binding constants of unknown ternary complexes, where G2 = hydrocarbons, were estimated, illustrating potential applications for sparsely soluble second guests.

Theoretical analysis of thermal boundary conductance of MoS2-SiO2 and WS2-SiO2 interface.

Understanding the physical processes involved in interfacial heat transfer is critical for the interpretation of thermometric measurements and the optimization of heat dissipation in nanoelectronic devices that are based on transition metal dichalcogenide (TMD) semiconductors. We model the phononic and electronic contributions to the thermal boundary conductance (TBC) variability for the MoS2-SiO2 and WS2-SiO2 interface. A phenomenological theory to model diffuse phonon transport at disordered interfaces is introduced and yields G = 13.5 and 12.4 MW K-1 m-2 at 300 K for the MoS2-SiO2 and WS2-SiO2 interface, respectively. We compare its predictions to those of the coherent phonon model and find that the former fits the MoS2-SiO2 data from experiments and simulations significantly better. Our analysis suggests that heat dissipation at the TMD-SiO2 interface is dominated by phonons scattered diffusely by the rough interface although the electronic TBC contribution can be significant even at low electron densities (n ≤ 1012 cm-2) and may explain some of the variation in the experimental TBC data from the literature. The physical insights from our study can be useful for the development of thermally aware designs in TMD-based nanoelectronics.

How Does Nature Evade the "Larger is Weaker" Fate of Ultralong Silk ß-Sheet Nanocrystallites.

Silk protein builds up one of the strongest fibers superior to most synthetic and natural polymers. However, the strengthening mechanisms of the silk proteins remain largely elusive because of their complex nanocomposite structures. Here, we report an unusual behavior of this kind of material that is distinctively different from those of metals and other polymers. We find that there are multiple interface microcracks nucleating and stacking under the shear loading, dividing the interchain interface into small segments, by which the silk protein can achieve a high strength even with the ultralong chains. This is a new strategy of microstructure design of soft matter that could avoid the "larger is weaker" fate due to the increase of the chain length. This novel mechanism is crucial for building strong polymer materials with long chain molecules and at the same time retaining their complex functional and structural properties.

Redox-Mediated Ambient Electrolytic Nitrogen Reduction for Hydrazine and Ammonia Generation.

This work presents a redox-mediated electrolytic nitrogen reduction reaction (RM-eNRR) using polyoxometalate (POM) as the electron and proton carrier which frees the TiO2 -based catalyst from the electrode and shifts the reduction of nitrogen to a reactor tank. The RM-eNRR process has achieved an ammonium production yield of 25.1 µg h-1 or 5.0 µg h-1 cm-2 at an ammonium concentration of 6.7 ppm. With high catalyst loading, 61.0 ppm ammonium was accumulated in the electrolyte upon continuous operation, which is the highest concentration detected for ambient eNRR so far. The mechanism underlying the RM-eNRR was scrutinized both experimentally and computationally to delineate the POM-mediated charge transfer and hydrogenation process of nitrogen molecule on the catalyst. RM-eNRR is expected to provide an implementable solution to overcome the limitations in the conventional eNRR process.

Theoretical analysis of thermal boundary conductance of MoS2-SiO2and WS2-SiO2interface.

Understanding the physical processes involved in interfacial heat transfer is critical for the interpretation of thermometric measurements and the optimization of heat dissipation in nanoelectronic devices that are based on transition metal dichalcogenide (TMD) semiconductors. We model the phononic and electronic contributions to the thermal boundary conductance (TBC) variability for the MoS2-SiO2and WS2-SiO2interface. A phenomenological theory to model diffuse phonon transport at disordered interfaces is introduced and yieldsG= 13.5 and 12.4 MW/K/m2at 300 K for the MoS2-SiO2and WS2-SiO2interface, respectively. We compare its predictions to those of the coherent phonon model and find that the former fits the MoS2-SiO2data from experiments and simulations significantly better. Our analysis suggests that heat dissipation at the TMD-SiO2interface is dominated by phonons scattered diffusely by the rough interface although the electronic TBC contribution can be significant even at low electron densities (n= 1012cm-2) and may explain some of the variation in the experimental TBC data from the literature. The physical insights from our study can be useful for the development of thermally aware designs in TMD-based nanoelectronics.

Neural network representation and optimization of thermoelectric states of multiple interacting quantum dots.

We perform quantum master equation calculations and machine learning to investigate the thermoelectric properties of multiple interacting quantum dots (MQD), including electrical conductance, Seebeck coefficient, thermal conductance and the figure of merit (ZT). We show that by learning from the data obtained from the QME, the thermoelectric states of the MQD can be represented well by a two-layer neural network. We also show that after training, the neural network was able to predict the thermoelectric properties of the MQD with much less computational cost compared to the QME approach. Based on the neural network, we further optimize the MQD to achieve a high ZT and power factor. This work presents a powerful route to study, represent, and optimize interacting quantum many-body systems.