Superelastic carbon aerogels have been widely explored by graphitic carbons and soft carbons. These soft aerogels usually have delicate microstructures with good fatigue resistance but ultralow ...strength. Hard carbon aerogels show great advantages in mechanical strength and structural stability due to the sp3‐C‐induced turbostratic “house‐of‐cards” structure. However, it is still a challenge to fabricate superelastic hard carbon‐based aerogels. Through rational nanofibrous structural design, the traditional rigid phenolic resin can be converted into superelastic hard carbon aerogels. The hard carbon nanofibers and abundant welded junctions endow the hard carbon aerogels with robust and stable mechanical performance, including superelasticity, high strength, extremely fast recovery speed (860 mm s−1), low energy‐loss coefficient (<0.16), long cycle lifespan, and heat/cold‐endurance. These emerging hard carbon nanofiber aerogels hold a great promise in the application of piezoresistive stress sensors with high stability and wide detection range (50 kPa), as well as stretchable or bendable conductors.
A family of hard carbon aerogels with nanofibrous structure templated by various nanofibers is fabricated, displaying robust and stable mechanical performances, including high strength, extremely fast recovery speed (860 mm s−1), and ultralow energy loss coefficient (<0.16). After being compressed for 104 cycles (50% strain), they show only ≈2% plastic deformation and retain ≈93% stress.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Energy efficient buildings require materials with a low thermal conductivity and a high fire resistance. Traditional organic insulation materials are limited by their poor fire resistance and ...inorganic insulation materials are either brittle or display a high thermal conductivity. Herein we report a mechanically resilient organic/inorganic composite aerogel with a thermal conductivity significantly lower than expanded polystyrene and excellent fire resistance. Co‐polymerization and nanoscale phase separation of the phenol‐formaldehyde‐resin (PFR) and silica generate a binary network with domain sizes below 20 nm. The PFR/SiO2 aerogel can resist a high‐temperature flame without disintegration and prevents the temperature on the non‐exposed side from increasing above the temperature critical for the collapse of reinforced concrete structures.
Fire not starter: Taking advantage of a co‐polymerization strategy an organic–inorganic binary network hybrid aerogel with a nanoscale homogeneity can be prepared. The phenol‐formaldehyde‐resin/SiO2 aerogel is mechanically resilient and has a thermal conductivity significantly lower than expanded polystyrene and excellent fire resistance.
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The flexibility in structural design of organic semiconductors endows organic solar cells (OSCs) not only great function-tunabilities, but also high potential toward practical application. In this ...work, simple non-fused-ring electron acceptors are developed through two-step synthesis from single aromatic units for constructing efficient OSCs. With the assistance of non-covalent interactions, these rotatable non-fused acceptors (in solution) allow transiting into planar and stackable conformation in condensed solid, promoting acceptors not only feasible solution-processability, but also excellent film characteristics. As results, decent power conversion efficiencies of 10.27% and 13.97% can be achieved in single and tandem OSCs consisting of simple solution-cast blends, in which the fully unfused acceptors exhibit exceptionally low synthetic complexity index. In addition, the unfused acceptor and its based OSCs exhibit promising stabilities under continuous illumination. Overall, this work reveals valuable insights on the structural design of simple and effective electron acceptors with great practical perspectives.
The mammalian mitochondrial electron transport chain (ETc) includes complexes I-IV, as well as the electron transporters ubiquinone and cytochrome c. There are two electron transport pathways in the ...ETC: complex I/III/IV, with NAdH as the substrate and complex II/III/IV, with succinic acid as the substrate. The electron flow is coupled with the generation of a proton gradient across the inner membrane and the energy accumulated in the proton gradient is used by complex V (ATP synthase) to produce ATP. The first part of this review briefly introduces the structure and function of complexes I-IV and ATP synthase, including the specific electron transfer process in each complex. Some electrons are directly transferred to O.sub.2 to generate reactive oxygen species (ROS) in the ETC. The second part of this review discusses the sites of ROS generation in each ETC complex, including sites I.sub.F and I.sub.Q in complex I, site II.sub.F in complex II and site III.sub.Qo in complex III, and the physiological and pathological regulation of ROS. As signaling molecules, ROS play an important role in cell proliferation, hypoxia adaptation and cell fate determination, but excessive ROS can cause irreversible cell damage and even cell death. The occurrence and development of a number of diseases are closely related to ROS overproduction. Finally, proton leak and uncoupling proteins (UCP.sub.S) are discussed. Proton leak consists of basal proton leak and induced proton leak. Induced proton leak is precisely regulated and induced by UCPs. A total of five UCPs (UCP1-5) have been identified in mammalian cells. UCP1 mainly plays a role in the maintenance of body temperature in a cold environment through non-shivering thermogenesis. The core role of UcP2-5 is to reduce oxidative stress under certain conditions, therefore exerting cytoprotective effects. All diseases involving oxidative stress are associated with UCPs.
As an abundant natural resource, wood has gained great attention for thousands of years, spanning from the primitive construction materials to the modern high‐added‐value engineering materials. The ...unique delicate microstructures and the wonderful properties (e.g., low‐density, high strength and stiffness, good toughness, and environmental sustainability) have made wood a natural source of inspiration that guides researchers to invent various wood‐inspired materials. Herein, as an emerging material system, bioinspired artificial wood, with similar cellular structures and comparable mechanical properties, is discussed in the view of the design concept, fabrication strategy, properties, and possible applications. The present challenges and further research opportunities are also presented for artificial woods to thrive. To achieve the final eco‐friendly artificial wood, more endeavors should be made in biomaterials and biodegradable or recyclable engineering of polymers to gain high mechanical properties and environmental sustainability simultaneously.
Artificial woods have emerged as a novel kind of wood‐inspired engineering material with almost exactly the same channel microstructures and similar wall components. The performances of artificial woods depend on both the oriented channel and wall designs. The rational combination of other engineering polymers and channel‐making techniques hold promise to develop more useful artificial woods.
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The anode oxygen evolution reaction (OER) is known to largely limit the efficiency of electrolyzers owing to its sluggish kinetics. While crystalline metal oxides are promising as OER catalysts, ...their amorphous phases also show high activities. Efforts to produce amorphous metal oxides have progressed slowly, and how an amorphous structure benefits the catalytic performances remains elusive. Now the first scalable synthesis of amorphous NiFeMo oxide (up to 515 g in one batch) is presented with homogeneous elemental distribution via a facile supersaturated co‐precipitation method. In contrast to its crystalline counterpart, amorphous NiFeMo oxide undergoes a faster surface self‐reconstruction process during OER, forming a metal oxy(hydroxide) active layer with rich oxygen vacancies, leading to superior OER activity (280 mV overpotential at 10 mA cm−2 in 0.1 m KOH). This opens up the potential of fast, facile, and scale‐up production of amorphous metal oxides for high‐performance OER catalysts.
Amorphous NiFeMo oxide (up to 515 g one batch) with homogeneous elemental distribution was synthesized through a facile supersaturated co‐precipitation method. The amorphous NiFeMo oxide undergoes rapid surface self‐reconstruction during OER that forms a metal oxy(hydroxide) active layer with oxygen vacancies, enabling efficient OER catalysis.
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SiOx is proposed as one of the most promising anodes for Li‐ion batteries (LIBs) for its advantageous capacity and stable Li uptake/release electrochemistry, yet its practical application is still a ...big challenge. Here encapsulation of SiOx nanoparticles into conductive graphene bubble film via a facile and scalable self‐assembly in solution is shown. The SiOx nanoparticles are closely wrapped in multilayered graphene to reconstruct a flake‐graphite‐like macrostructure, which promises uniform and agglomeration‐free distribution of SiOx in the carbon while ensures a high mechanical strength and a high tap density of the composite. The composites present unprecedented cycling stability and excellent rate capabilities upon Li storage, rendering an opportunity for its anode use in the next‐generation high‐energy LIBs.
SiOx nanoparticles are closely wrapped in multilayered graphene to reconstruct a macrostructure resembling flake graphite, which promises agglomeration‐free distribution of SiOx in the bulk while ensuring a high mechanical strength and a high tap density of the bubble film. By taking the advantages of the graphene network, the composites present unprecedented cycling stability and excellent rate capabilities upon Li storage.
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Background and Aims
The study objective was to compare the effectiveness of microwave ablation (MWA) and laparoscopic liver resection (LLR) on solitary 3–5‐cm HCC over time.
Approach and Results
From ...2008 to 2019, 1289 patients from 12 hospitals were enrolled in this retrospective study. Diagnosis of all lesions were based on histopathology. Propensity score matching was used to balance all baseline variables between the two groups in 2008–2019 (n = 335 in each group) and 2014–2019 (n = 257 in each group) cohorts, respectively. For cohort 2008–2019, during a median follow‐up of 35.8 months, there were no differences in overall survival (OS) between MWA and LLR (HR: 0.88, 95% CI 0.65–1.19, p = 0.420), and MWA was inferior to LLR regarding disease‐free survival (DFS) (HR 1.36, 95% CI 1.05–1.75, p = 0.017). For cohort 2014–2019, there was comparable OS (HR 0.85, 95% CI 0.56–1.30, p = 0.460) and approached statistical significance for DFS (HR 1.33, 95% CI 0.98–1.82, p = 0.071) between MWA and LLR. Subgroup analyses showed comparable OS in 3.1–4.0‐cm HCCs (HR 0.88, 95% CI 0.53–1.47, p = 0.630) and 4.1–5.0‐cm HCCs (HR 0.77, 95% CI 0.37–1.60, p = 0.483) between two modalities. For both cohorts, MWA shared comparable major complications (both p > 0.05), shorter hospitalization, and lower cost to LLR (all p < 0.001).
Conclusions
MWA might be a first‐line alternative to LLR for solitary 3–5‐cm HCC in selected patients with technical advances, especially for patients unsuitable for LLR.
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Catalytic difunctionalization of alkenes has been an ideal strategy to generate structurally complex molecules with diverse substitution patterns. Although both phosphonyl and carboxyl groups are ...valuable functional groups, the simultaneous incorporation of them via catalytic difunctionalization of alkenes, ideally from abundant, inexpensive and easy-to-handle raw materials, has not been realized. Herein, we report the phosphonocarboxylation of alkenes with CO
via visible-light photoredox catalysis. This strategy is sustainable, general and practical, providing facile access to important β-phosphono carboxylic acids, including structurally complex unnatural α-amino acids. Diverse alkenes, including enamides, styrenes, enolsilanes and acrylates, undergo such reactions efficiently under mild reaction conditions. Moreover, this method represents a rare example of redox-neutral difunctionalization of alkenes with H-P(O) compounds, including diaryl- and dialkyl- phosphine oxides and phosphites. Importantly, these transition-metal-free reactions also feature low catalyst loading, high regio- and chemo-selectivities, good functional group tolerance, easy scalability and potential for product derivatization.
Photo-degradation of organic semiconductors remains as an obstacle preventing their durable practice in optoelectronics. Herein, we disclose that volume-conserving photoisomerization of a unique ...series of acceptor-donor-acceptor (A-D-A) non-fullerene acceptors (NFAs) acts as a surrogate towards their subsequent photochemical reaction. Among A-D-A NFAs with fused, semi-fused and non-fused backbones, fully non-fused PTIC, representing one of rare existing samples, exhibits not only excellent photochemical tolerance in aerobic condition, but also efficient performance in solar cells. Along with a series of in-depth investigations, we identify that the structural confinement to inhibit photoisomerization of these unique A-D-A NFAs from molecular level to macroscopic condensed solid helps enhancing the photochemical stabilities of molecules, as well as the corresponding OSCs. Although other reasons associating with the photostabilities of molecules and devices should not excluded, we believe this work provides helpful structure-property information toward new design of stable and efficient photovoltaic molecules and solar cells.
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