Most two-dimensional (2D) covalent organic frameworks (COFs) are non-fluorescent in the solid state even when they are constructed from emissive building blocks. The fluorescence quenching is usually ...attributed to non-irradiative rotation-related or π-π stacking-caused thermal energy dissipation process. Currently there is a lack of guiding principle on how to design fluorescent, solid-state material made of COF. Herein, we demonstrate that the eclipsed stacking structure of 2D COFs can be used to turn on, and tune, the solid-state photoluminescence from non-emissive building blocks by the restriction of intramolecular bond rotation via intralayer and interlayer hydrogen bonds among highly organized layers in the eclipse-stacked COFs. Our COFs serve as a platform whereby the size of the conjugated linkers and side-chain functionalities can be varied, rendering the emission colour-tuneable from blue to yellow and even white. This work provides a guide to design new solid-state emitters using COFs.
Covalent organic frameworks (COFs) are an emerging class of porous crystalline materials constructed from designer molecular building blocks that are linked and extended periodically via covalent ...bonds. Their high stability, open channels, and ease of functionalization suggest that they can function as a useful cathode material in reversible lithium batteries. Here, a COF constructed from hydrazone/hydrazide‐containing molecular units, which shows good CO2 sequestration properties, is reported. The COF is hybridized to Ru‐nanoparticle‐coated carbon nanotubes, and the composite is found to function as highly efficient cathode in a Li–CO2 battery. The robust 1D channels in the COF serve as CO2– and lithium‐ion‐diffusion channels and improve the kinetics of electrochemical reactions. The COF‐based Li–CO2 battery exhibits an ultrahigh capacity of 27 348 mAh g−1 at a current density of 200 mA g−1, and a low cut‐off overpotential of 1.24 V within a limiting capacity of 1000 mAh g−1. The rate performance of the battery is improved considerably with the use of the COF at the cathode, where the battery shows a slow decay of discharge voltage from a current density of 0.1 to 4 A g−1. The COF‐based battery runs for 200 cycles when discharged/charged at a high current density of 1 A g−1.
A covalent organic framework (COF) is deployed in a Li–CO2 battery to function as diffusion channels to improve gas/ion migration. Owing to its ability for CO2 capture/release, the COF greatly increases the battery's specific discharge capacity. Importantly, the COF also enhances the battery's rate performance and cycling life at high current density due to the presence of the 1D channels that enable fast gas/ion diffusion.
Non-alcoholic fatty liver disease (NAFLD) has emerged as one of the most frequent types of liver disease in pediatric populations with obesity. Tilianin has multiple biological activities including ...anti-inflammatory and antioxidant. Here, we aim to explore the functions and possible mechanisms of tilianin on NAFLD in obese children. A high-fat high-carbohydrate (HFHC) diet was used to feed 21-d-old mice. Tilianin was administered at a dose of 10 or 20 mg/kg daily. HFHC-fed mice gained weight, increased liver index. The liver showed hepatocyte ballooning, inflammatory infiltration, and steatosis. Elevated levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGT), low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) and reduced the high-density lipoprotein cholesterol (HDL-C) level were found in HFHC-fed mice. Administration of tilianin significantly reduced these impairments. We further evaluated proteins related to lipid metabolism and observed that LXRα, SREBP-1c, FAS and ACC1 expression were blunted following tilianin administration. In addition, tilianin suppressed reactive oxygen species (ROS) overproduction and lipid peroxide 4-Hydroxynonenal expression, ascribed to its oxidative stress-modulating capacity. Tilianin also reversed the increase in F4/80 expression and proinflammatory cytokine levels. Of note, tilianin administration resulted in decreased protein levels of active caspase-1 and NOD-like receptor protein 3 (NLRP3) in HFHC-fed mice. Our study suggests that tilianin may ameliorate NAFLD in early obese mice by modulating lipids metabolism, oxidative stress, and inflammation, which may in part involve inhibiting NLRP3 inflammasome activation.
Based on the time and location information of nodes, multi-sensor complex networks can achieve high-speed and low-delay exchange of control and sensor data between sensor nodes to ensure the accuracy ...and real-time performance of the entire detection and control system. However, complex multi-sensor networks face limitations in terms of computing, storage, and network resources. After grouping the sensor data of nodes, this paper employs an adaptive weighted data fusion method to complete the data fusion processing in the network. This approach can significantly reduce the data redundancy in the wireless sensor network, save a large amount of storage resources, and lower the network bandwidth occupation, with high efficiency and good scalability. The least square (LS) fitting is performed by two sets of temperature and humidity data obtained by weighted fusion at the cluster head node. Experimental results indicate that the fusion of two-dimensional data transmitted to the base station or control center can further diminish the amount of data transmission. In addition, after the adaptive weighted data fusion of the two-dimensional data at the cluster head node, the energy consumption of the cluster head node without the fusion and the cluster head node after the fusion is compared. The results demonstrate that the energy consumption of the cluster head node is notably abridged, the energy of the cluster head node is saved to a greater extent, and the life cycle of the network is prolonged.
Use of supersaturable formulations has been demonstrated as an effective approach to improve solubility and oral absorption of poorly water-soluble compounds. In supersaturable formulations, drug ...concentration exceeds the equilibrium solubility when the formulations are exposed to the gastrointestinal fluids and drug might precipitate before being absorbed, resulting in delayed response, and reduced efficacy or compromised bioavailability. Polymer based drug precipitation inhibitors have been used to inhibit or retard such precipitation. In this manner one can maintain a drug in the supersaturated concentration for an extended period of time, leading to significantly improved bioavailability of the poorly water-soluble drugs. This review article discusses different types of precipitation inhibitors, working hypotheses, and case studies with improved oral bioavailability.
Although polymers have been studied for well over a century, there are few examples of covalently linked polymer crystals synthesised directly from solution. One-dimensional (1D) covalent polymers ...that are packed into a framework structure can be viewed as a 1D covalent organic framework (COF), but making a single crystal of this has been elusive. Herein, by combining labile metal coordination and dynamic covalent chemistry, we discover a strategy to synthesise single-crystal metallo-COFs under solvothermal conditions. The single-crystal structure is rigorously solved using single-crystal electron diffraction technique. The non-centrosymmetric metallo-COF allows second harmonic generation. Due to the presence of syntactic pendant amine groups along the polymer chains, the metallopolymer crystal can be further cross-linked into a crystalline woven network.
Extracting high-molecular-weight DNA is critical for successful long-read DNA sequencing. Here, we present a DNA preparation procedure combining the CTAB DNA extraction protocol and a short-read ...eliminator kit, which consistently produces high yields of high-molecular-weight DNA in the freshwater microcrustacean Daphnia. This method only requires common chemicals and equipment, providing researchers a viable alternative to DNA extraction kits that often require specialized tools.
Although existing deep superpixel methods have significantly improved the performance, they are generally dataset-specific and need re-training for unseen data. This issue results in the failure of ...deep superpixel methods when facing untrainable application scenarios. In this letter, we propose a novel deep superpixel algorithm to enhance the domain adaptability and generalization performance of deep superpixel methods. Specifically, we propose the domain-free embedding to replace traditional LAB color coding, reducing the network's reliance on training set statistical properties by narrowing the gap between training data and the real-world domain shift. Simultaneously, to prevent performance loss due to color information loss, we introduce the reconstructed contour constraint to directly enhance the boundary-fitting capability of superpixels. Experimental results demonstrate that our superpixel model achieve optimal cross-domain adaptation capability with just one training session, even facing extreme domain shift.
A strategy for the synthesis of N,N‐disubstituted hydrazines via the electrocatalytic addition of hydrazine to α,β‐unsaturated carbonyl compounds is reported. The reaction was carried out under ...constant current electrolytic conditions in an undivided cell. Using this methodology, various N,N‐disubstituted hydrazines were prepared in 57–94% yield in 40 minutes. By adding cyclohexanone and acetic acid to the reaction mixture of N,N‐disubstituted hydrazines and heating for 2 hours, a one‐pot synthesis of N‐substituted indoles was also developed. Furthermore, based on cyclic voltammetry and control experiments, a plausible mechanism involving a radical pathway is proposed.
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