Two-dimensional materials provide extraordinary opportunities for exploring phenomena arising in atomically thin crystals. Beginning with the first isolation of graphene, mechanical exfoliation has ...been a key to provide high-quality two-dimensional materials, but despite improvements it is still limited in yield, lateral size and contamination. Here we introduce a contamination-free, one-step and universal Au-assisted mechanical exfoliation method and demonstrate its effectiveness by isolating 40 types of single-crystalline monolayers, including elemental two-dimensional crystals, metal-dichalcogenides, magnets and superconductors. Most of them are of millimeter-size and high-quality, as shown by transfer-free measurements of electron microscopy, photo spectroscopies and electrical transport. Large suspended two-dimensional crystals and heterojunctions were also prepared with high-yield. Enhanced adhesion between the crystals and the substrates enables such efficient exfoliation, for which we identify a gold-assisted exfoliation method that underpins a universal route for producing large-area monolayers and thus supports studies of fundamental properties and potential application of two-dimensional materials.
The homeostatic link between oxidative stress and autophagy plays an important role in cellular responses to a wide variety of physiological and pathological conditions. However, the regulatory ...pathway and outcomes remain incompletely understood. Here, we show that reactive oxygen species (ROS) function as signaling molecules that regulate autophagy through ataxia‐telangiectasia mutated (ATM) and cell cycle checkpoint kinase 2 (CHK2), a DNA damage response (DDR) pathway activated during metabolic and hypoxic stress. We report that CHK2 binds to and phosphorylates Beclin 1 at Ser90/Ser93, thereby impairing Beclin 1‐Bcl‐2 autophagy‐regulatory complex formation in a ROS‐dependent fashion. We further demonstrate that CHK2‐mediated autophagy has an unexpected role in reducing ROS levels via the removal of damaged mitochondria, which is required for cell survival under stress conditions. Finally, CHK2−/− mice display aggravated infarct phenotypes and reduced Beclin 1 p‐Ser90/Ser93 in a cerebral stroke model, suggesting an in vivo role of CHK2‐induced autophagy in cell survival. Taken together, these results indicate that the ROS‐ATM‐CHK2‐Beclin 1‐autophagy axis serves as a physiological adaptation pathway that protects cells exposed to pathological conditions from stress‐induced tissue damage.
Synopsis
Whether hypoxia and nutrient starvation are coupled to cellular autophagy remains unclear. Here, DNA damage response kinases ATM and CHK2 are shown to trigger autophagy in response to reactive oxygen species (ROS) accumulation, suggesting a novel physiological adaptation pathway toward metabolic stress.
Depletion of CHK2 or ATM impairs oxidative stress‐induced autophagy in MEFs.
CHK2 binds and phosphorylates Beclin1 at Ser90/Ser93, suppressing Beclin1‐Bcl‐2 autophagy regulatory complex formation.
CHK2‐induced autophagy limits intracellular ROS levels by clearing damaged mitochondria.
CHK2‐induced autophagy protects against cell death and tissue damage following cerebral ischemia.
ROS accumulation activates protective autophagy to prevent stress‐induced tissue damage.
Most gels and elastomers introduce sacrificial bonds in the covalent network to dissipate energy. However, long‐term cyclic loading caused irreversible fatigue damage and crack propagation cannot be ...prevented. Furthermore, because of the irreversible covalent crosslinked networks, it is a huge challenge to implement reversible mechanical interlocking and reorganize the polymer segments to realize the recycling and reuse of ionogels. Here, covalent crosslinking of host materials is replaced with entanglement. The entangled microdomains are used as physical crosslinking while introducing reversible bond interactions. The interpenetrating, entangled, and elastic microdomains of linear segments and covalent‐network microspheres provide mechanical stability, eliminate stress concentration at the crack tip under load, and achieve unprecedented tear and fatigue resistance of ionogels in any load direction. Moreover, reversible entanglements and noncovalent interactions can be disentangled and recombined to achieve recycling and mechanical regeneration, and the recyclability of covalent‐network microdomains is realized.
Irreversible covalent crosslinking in the matrix polymer network is avoided. The reversible entangled microdomains of the microspheres and linear segments in tough ionogels act as elastic physical crosslinking points to provide mechanical stability, dissipate stress concentration, and prevent crack propagation in any load direction. The entangled networks can be disentangled to restore the damaged mechanical properties and realize recycling.
Porous ionic polymers (PiPs) are newly emerging organic porous polymers. In sharp contrast to charge-neutral porous polymers, ionic moieties are either incorporated into the polymer backbone, or are ...covalently attached to a polymeric framework. Therefore, their physicochemical properties, functional groups, and active sites can be easily modified through screening of building blocks and ionic tectons. Meanwhile, their surface area, pore size, and pore volume can also be tuned by counterions exchange. Intrinsic functionalization further broadens the application range of the PiPs. This review will describe the recent advancements with regard to PiPs, and their development in the area of gas adsorption, catalysis, antibacterial applications and water purification.
Herein, the design and synthesis of ZIF‐67 nanoparticles (NPs) with tunable size grown inside hollow carbon nanospheres (ZIF‐67@HCSs) via a space‐confined strategy is reported. HCSs are first ...prepared via pyrolysis of polystyrene@polypyrrole (PS@PPy) composite nanospheres. Further infiltration of 2‐methylimidazole (MI) into the HCSs (MI@HCSs) using a melting‐diffusion strategy, followed by immersing MI@HCSs into Co(NO3)2 solution through the pores and channels of HCSs results in the formation of ZIF‐67@HCSs. The as‐synthesized ZIF‐67@HCSs with tunable ZIF‐67 size is achieved by changing the amount of MI. Due to the high pore volume provided by nanoscale ZIF‐67 NPs, the as‐prepared core–shell ZIF‐67@HCSs exhibit outstanding adsorption capacity for CO2.
A facile strategy of space‐confined synthesis of ZIF‐67 nanoparticles in hollow carbon nanospheres (ZIF‐67@HCSs) is developed, in which the as‐prepared ZIF‐67@HCSs with nanoscale ZIF‐67 nanocrystals exhibit high CO2 adsorption capacity and high selectivity of CO2 over N2.
Electronic skin can detect minute electrical potential changes in the human skin and represent the body's state, which is critical for medical diagnostics and human–computer interface development. On ...the other hand, sweat has a significant effect on the signal stability, comfort, and safety of electronic skin in a real‐world application. In this study, by modifying the cation and anion of a poly(ionic liquid) (PIL) and employing a spinning process, a PIL‐based multilayer nanofiber membrane (PIL membrane) electronic skin with a dual gradient is created. The PIL electronic skin is moisture‐wicking and breathable due to the hydrophilicity and pore size‐gradients. The intrinsically antimicrobial activities of PILs allow the safe collection of bioelectrical signals from the human body, such as electrocardiography (ECG) and electromyography (EMG). In addition, a robotic hand may be operated in real‐time, and a preliminary human–computer interface can be accomplished by simple processing of the collected EMG signal. This study establishes a novel practical approach for monitoring and using bioelectrical signals in real‐world circumstances via the multifunctional electronic skin.
A dual‐gradient poly(ionic liquid) electronic skin with moisture‐wicking, breathable, and antibacterial properties is prepared. Sweat can be delivered to the outside, away from the skin, keeping the electrode‐skin interface dry, ensuring stable and safe collection of bioelectric signals, further enabling real‐time control of a robotic hand. This work provides an unprecedented practical strategy for monitoring and utilization of bioelectrical signals under real conditions.
Tin‐based perovskites with excellent optoelectronic properties and suitable band gaps are promising candidates for the preparation of efficient lead‐free perovskite solar cells (PSCs). However, it is ...challenging to prepare highly stable and efficient tin‐based PSCs because Sn2+ in perovskites can be easily oxidized to Sn4+ upon air exposure. Here we report the fabrication of air‐stable FASnI3 solar cells by introducing hydroxybenzene sulfonic acid or its salt as an antioxidant additive into the perovskite precursor solution along with excess SnCl2. The interaction between the sulfonate group and the Sn2+ ion enables the in situ encapsulation of the perovskite grains with a SnCl2–additive complex layer, which results in greatly enhanced oxidation stability of the perovskite film. The corresponding PSCs are able to maintain 80 % of the efficiency over 500 h upon air exposure without encapsulation, which is over ten times longer than the best result reported previously. Our results suggest a possible strategy for the future design of efficient and stable tin‐based PSCs.
Protective coating: A tin‐based perovskite solar cell with significantly improved stability to oxidation was prepared by introducing hydroxybenzene sulfonic acid or a salt thereof as an antioxidant additive into the perovskite precursor solution. The resulting perovskite grains are encapsulated by a SnCl2–additive complex layer.
Elevated levels of neutrophils have been associated with poor survival in various cancers, but direct evidence supporting a role for neutrophils in the immunopathogenesis of human cancers is lacking.
...A total of 573 patients with gastric cancer were enrolled in this study. Immunohistochemistry and real-time PCR were performed to analyze the distribution and clinical relevance of neutrophils in different microanatomic regions. The regulation and function of neutrophils were assessed both
and
Increased neutrophil counts in the peripheral blood were associated with poor prognosis in gastric cancer patients. In gastric cancer tissues, neutrophils were enriched predominantly in the invasive margin, and neutrophil levels were a powerful predictor of poor survival in patients with gastric cancer. IL17
neutrophils constitute a large portion of IL17-producing cells in human gastric cancer. Proinflammatory IL17 is a critical mediator of the recruitment of neutrophils into the invasive margin by CXC chemokines. Moreover, neutrophils at the invasive margin were a major source of matrix metalloproteinase-9, a secreted protein that stimulates proangiogenic activity in gastric cancer cells. Accordingly, high levels of infiltrated neutrophils at the invasive margin were positively correlated with angiogenesis progression in patients with gastric cancer.
These data provide direct evidence supporting the pivotal role of neutrophils in gastric cancer progression and reveal a novel immune escape mechanism involving fine-tuned collaborative action between cancer cells and immune cells in the distinct tumor microenvironment.
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Attributed to its advantages of super mechanical flexibility, very low-temperature processing, and compatibility with low cost and high throughput manufacturing, organic thin-film transistor (OTFT) ...technology is able to bring electrical, mechanical, and industrial benefits to a wide range of new applications by activating nonflat surfaces with flexible displays, sensors, and other electronic functions. Despite both strong application demand and these significant technological advances, there is still a gap to be filled for OTFT technology to be widely commercially adopted. This paper provides a comprehensive review of the current status of OTFT technologies ranging from material, device, process, and integration, to design and system applications, and clarifies the real challenges behind to be addressed.
Alkaline alcohols (methanol, ethanol, propanol, and ethylene glycol) have been applied as fuels for alkaline anion exchange membrane fuel cells. However, the effects of alkaline media on the ...stability of anion exchange membranes (AEMs) are still elusive. Here, a series of organic cations including quaternary ammonium, imidazolium, benzimidazolium, pyridinium, phosphonium, pyrrolidinium cations, and their corresponding cationic polymers are synthesized and systematically investigated with respect to their chemical stability in various alkaline media (water, methanol, ethanol, and dimethyl sulfoxide) by quantitative 1H nuclear magnetic resonance spectroscopy and density functional theory calculations. In the case of protic solvents (water, methanol, and ethanol), the lower dielectric constant of the alkaline media, the lower is the lowest unoccupied molecular orbital (LUMO) energy of the organic cation, which leads to the lower alkaline stability of cations. However, the hydrogen bonds between the anions and protic solvents weaken the effects of low dielectric constant of the alkaline media. The aprotic solvent accelerated the SN2 degradation reaction of “naked” organic cations. The results of this study suggest that both the chemical structure of organic cations and alkaline media (fuels) applied affect the alkaline stability of AEMs.
The alkaline stability of organic cations and cationic polymers in various alkaline media (water, methanol, ethanol and DMSO) is characterized using quantitative 1H NMR spectra and density functional theory calculations.
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