Covalent organic frameworks (COFs) are a class of organic crystalline porous materials discovered in the early 21st century that have become an attractive class of emerging materials due to their ...high crystallinity, intrinsic porosity, structural regularity, diverse functionality, design flexibility, and outstanding stability. However, many chemical and physical properties strongly depend on the presence of metal ions in materials for advanced applications, but metal-free COFs do not have these properties and are therefore excluded from such applications. Metalated COFs formed by combining COFs with metal ions, while retaining the advantages of COFs, have additional intriguing properties and applications, and have attracted considerable attention over the past decade. This review presents all aspects of metalated COFs, from synthetic strategies to various applications, in the hope of promoting the continued development of this young field.
This review highlights the recent advances of metalated covalent organic frameworks, including synthetic strategies and applications, and discusses the current challenges and future directions.
Stimuli-responsive hydrogel actuators have promising applications in various fields. However, the typical hydrogel actuation relies on the swelling and de-swelling process caused by osmotic-pressure ...changes, which is slow and normally requires the presence of water environment. Herein, we report a light-powered in-air hydrogel actuator with remarkable performances, including ultrafast motion speed (up to 1.6 m/s), rapid response (as fast as 800 ms) and high jumping height (~15 cm). The hydrogel is operated based on a fundamentally different mechanism that harnesses the synergetic interactions between the binary constituent parts, i.e. the elasticity of the poly(sodium acrylate) hydrogel, and the bubble caused by the photothermal effect of the embedded magnetic iron oxide nanoparticles. The current hydrogel actuator exhibits controlled motion velocity and direction, making it promising for a wide range of mobile robotics, soft robotics, sensors, controlled drug delivery and other miniature device applications.
At present, high-solids anaerobic digestion of sewage sludge has drawn great attention due to the superiority of its small land area footprint and low energy consumption. However, a high organic ...loading rate may cause acids accumulation and ammonia inhibition, thus leading to an inhibited pseudo-steady state in which electron transfer through interspecies hydrogen transfer (IHT) between acetogens and methanogens is blocked. In this study, adding 50 mg/g TS (total solid) magnetite clearly reduced the accumulation of short-chain fatty acids and accelerated methane production by 26.6%. As demonstrated, the individual processes of anaerobic digestion could not be improved by magnetite when methanogenesis was interrupted. Analyzing stable carbon isotopes and investigating the methanogenesis pathways using acetate and H2/CO2 as substrates together proved that direct interspecies electron transfer (DIET) was enhanced by magnetite. Metatranscriptomic analysis and determination of key enzymes showed that IHT could be partially substituted by enhanced DIET, and acetate-dependent methanogenesis was improved after the blockage of electron transfer was scavenged. Additionally, the expression of both pili and c-type cytochromes was found to decrease, indicating that magnetite could replace their roles for efficient electron transfer between acetogens and methanogens; thus, a robust chain of electron transfer was established.
Covalent organic frameworks (COFs), as a new emerging class of highly crystalline advanced porous materials with fascinating structural tunability and diversity as well as the desired semiconductor ...properties, have gained significant attention as highly promising and efficient photocatalysts or designer platforms for a variety of photocatalytic applications in recent years; thus a comprehensive review is timely to summarize the advances of this field. In this review, a background and brief timeline concerning the developments and key achievements of COFs are provided. Afterwards, a systematic overview of the potential photocatalytic applications realized to date in the fast growing field of COFs is provided with the aim of presenting a full blueprint of COFs for possible photochemical energy conversion and reactions. Finally, the challenges remaining and personal perspectives on further development of this type of material for photocatalysis are presented.
In this review, a comprehensive summary of the potential photocatalytic applications realized to date in the fast-growing field of COFs is provided with the aim to present a full blueprint of COFs for photochemical energy conversion and reactions.
As newly emerged crystalline porous materials, covalent organic frameworks (COFs) possess fascinating structures and some specific features such as modularity, crystallinity, porosity, stability, ...versatility, and biocompatibility. Besides adsorption/separation, sensing, catalysis, and energy applications, COFs have recently shown a promise in biomedical applications. This contribution provides an overview of the recent developments of COF‐based medicines in cancer therapeutics, including drug delivery, photodynamic therapy (PDT), photothermal therapy (PTT), and combined therapy. Furthermore, the major challenges and developing trends in this field are also discussed. These recent developments are summarized and discussed to help encourage further contributions in this emerging and promising field.
Magic bullet: In this minireview, recent advances in the field of covalent organic frameworks (COFs) for cancer therapeutic applications are highlighted, including those for drug delivery, phototherapy, and combined therapy.
This study explores the causes of corruption in China using provincial panel data. Using both fixed effects and instrumental variables approaches, we find that provinces with greater anti-corruption ...efforts, higher educational attainment, historic influence from Anglo-American church universities, greater openness, more access to media, higher relative wages of government employees and a greater representation of women in the legislature are markedly less corrupt; whereas social heterogeneity, regulation and resources abundance breed substantial corruption. We also find that fiscal decentralization depresses corruption significantly. Finally, we identify a positive relationship between corruption and economic development in China, which is driven primarily by the transition to a market economy.
► We study the causes of corruption in China with provincial panel data. ► Educational attainment, trade openness and news media curb provincial corruption. ► Fiscal decentralization and high relative wages of officials prevent corruption. ► Social heterogeneity, regulation and resource abundance breed regional corruption. ► Economic development has a positive effect on corruption in current China.
For seeking high enantiopurity, the previously reported thermal asymmetric catalysis is usually carried out at low temperature sometimes with limited yield, that is, the high enantiomeric excess (ee) ...usually at the cost of high yield. Thus, the achieving both high stereoselectivity and yield is an enormous challenge. We report herein two metal nanoparticle (M NP)-loaded and porphyrin-containing homochiral covalent organic framework (CCOF)-based composite catalysts, and their application in the thermally-driven asymmetric one-pot Henry and A
-coupling reactions. All the reactions are conducted at elevated temperatures with both excellent stereoselectivity and yield which resulted from the synergy of CCOF confinement effect and M NP catalytic activation. Notably, the needed thermal energy for the asymmetric reactions herein is derived from the photothermal conversion via porphyrin-based CCOF upon irradiation with visible light. Remarkably, the CCOF confinement effect can be effectively maintained up to 100 °C for the asymmetric one-pot Henry and A
-coupling reactions herein.
Ca2+, a ubiquitous but nuanced modulator of cellular physiology, is meticulously controlled intracellularly. However, intracellular Ca2+ regulation, such as mitochondrial Ca2+ buffering capacity, can ...be disrupted by 1O2. Thus, the intracellular Ca2+ overload, which is recognized as one of the important cell pro‐death factors, can be logically achieved by the synergism of 1O2 with exogenous Ca2+ delivery. Reported herein is a nanoscale covalent organic framework (NCOF)‐based nanoagent, namely CaCO3@COF‐BODIPY‐2I@GAG (4), which is embedded with CaCO3 nanoparticle (NP) and surface‐decorated with BODIPY‐2I as photosensitizer (PS) and glycosaminoglycan (GAG) targeting agent for CD44 receptors on digestive tract tumor cells. Under illumination, the light‐triggered 1O2 not only kills the tumor cells directly, but also leads to their mitochondrial dysfunction and Ca2+ overload. An enhanced antitumor efficiency is achieved via photodynamic therapy (PDT) and Ca2+ overload synergistic therapy.
A multifunctional COF‐based nanoagent, which is equipped with BODIPY‐2I photosensitizer, CaCO3 nanoparticle, and glycosaminoglycan (GAG) targeting agent, can be a highly efficient and selective antitumor nanomedicine for colon tumor via photodynamic therapy (PDT) and Ca2+ overload synergistic therapy.
Cloud-phase algorithms based on satellite infrared (IR) observations typically use empirical thresholds and additional cloud properties to predict cloud phases, but these settings may not be ...consistently accurate under various conditions. This study introduces an unsupervised machine learning approach based on a Gaussian mixture model (GMM) to avoid the empirical determination of thresholds and auxiliary cloud products for cloud-phase estimation. The GMM-based cloud-phase algorithm proposed in the present study consists of three GMMs that distinguish cluster types representing water, ice, and undetermined phases using the brightness temperature (TB) at 11.2 μm and the difference in TB between 8.6 and 11.2 μm from GEO-KOMPSAT-2A (GK2A) satellite. The first GMM initially classifies four clusters, while the second and third GMMs re-group the initial clusters to distinguish supercooled water, mixed-phase, and optically thin cirrus clouds. The GMM-derived estimates are compared with operational cloud-phase products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar with Infrared Pathfinder Satellite Observations (CALIOP). Results show that the water and ice phases estimated using the GMM-based algorithm are in good agreement with both the MODIS and CALIOP products. The GMM-based algorithm also significantly reduces the misidentified area for undetermined phases observed in the GK2A operational product. Water and ice phases are also effectively estimated in warm regions, resulting in distributions similar to those derived from MODIS and CALIOP products. Unlike most IR cloud-phase algorithms that utilize thresholds and other cloud parameters, the GMM-based cloud-phase algorithm has the advantage of using only TB, thus avoiding auxiliary cloud properties.
Chemodynamic therapy (CDT), which induces cell death by decomposing high levels of H2O2 in tumor cells into highly toxic ·OH, is recognized as a promising antineoplastic approach. However, current ...CDT approaches are often restricted by the highly controlled and upregulated cellular antioxidant defense. To enhance ·OH‐induced cellular damage by CDT, a covalent organic framework (COF)‐based, ferrocene (Fc)‐ and glutathione peroxidase 4 (GPX4) inhibitor‐loaded nanodrug, RSL3@COF–Fc (2b), is fabricated. The obtained 2b not only promotes in situ Fenton‐like reactions to trigger ·OH production in cells, but also attenuates the repair mechanisms under oxidative stress via irreversible covalent GPX4 inhibition. As a result, these two approaches synergistically result in massive lipid peroxide accumulation, subsequent cell damage, and ultimately ferroptosis, while not being limited by intracellular glutathione. It is believed that this research provides a paradigm for enhancing reactive oxygen species‐mediated oncotherapy through redox dyshomeostasis and may provide new insights for developing COF‐based nanomedicine.
Versatile covalent organic frameworks (COFs)! The organic nanodrug RSL3@COF–Fc (2b), which integrates the glutathione peroxidase 4 inhibitor RSL3 and Fenton‐like reaction catalyst ferrocene (Fc) into a nanoscale COF, induces ferroptosis to enhance chemodynamic therapy by blocking lipid repair and disrupting cellular redox homeostasis.
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