N‐Heterocycles, such as pyrroles, pyrimidines, quinazolines, and quinoxalines, are important building blocks for organic chemistry and the fine‐chemical industry. For their synthesis, catalytic ...borrowing hydrogen and acceptorless dehydrogenative coupling reactions of alcohols as sustainable reagents have received significant attention in recent years. To overcome the problems of product separation and catalyst reusability, several metal‐based heterogeneous catalysts have been reported to achieve these transformations with good yields and selectivity. In this Minireview, we summarize recent developments using both noble and non‐noble metal‐based heterogeneous catalysts to synthesize N‐heterocycles from alcohols and N‐nucleophiles via acceptorless dehydrogenation or borrowing hydrogen methodologies. Furthermore, this Minireview introduces strategies for the preparation and functionalization of the corresponding heterogeneous catalysts, discusses the reaction mechanisms and the roles of metal electronic states, and the influence of support Lewis acid–base properties on these reactions.
This Minireview summarizes recent developments in which both noble and non‐noble metal‐based heterogeneous catalysts are used to synthesize N‐heterocycles from alcohols and N‐nucleophiles via acceptorless dehydrogenation or borrowing hydrogen methodologies. The strategies for the preparation and functionalization of heterogeneous catalysts, reaction mechanisms, and the roles of heterogeneous catalysts in these reactions are also discussed.
This technical note presents necessary and sufficient conditions for the stability and stabilization of fractional-order interval systems. The results are obtained in terms of linear matrix ...inequalities. Two illustrative examples are given to show that our results are effective and less conservative for checking the robust stability and designing the stabilizing controller for fractional-order interval systems.
The electrocaloric effect (ECE) in dielectric materials has great potential in realizing solid‐state cooling devices with compact size and high efficiency, which are highly desirable for a broad ...range of applications. This paper presents the general considerations for dielectric materials to achieve large ECE and reviews the experimental efforts investigating ECE in various polar dielectrics. For practical cooling devices, an ECE material must possess a large isothermal entropy change besides a large adiabatic temperature change. We show that polar dielectrics operated at temperatures near order–disorder transition have potential to achieve large ECE due to the possibility of large change in polarization induced by electric field and large entropy change associated with the polarization change. We further show that indeed the ferroelectric poly(vinylidene fluoride–trifluoroethylene)‐based polymers display a large ECE, i.e., an isothermal entropy change of more than 55 J (kgK)−1 and an adiabatic temperature change of more than 12 °C, at temperatures above the order–disorder transition.
Applying an electrical field to a dielectric may induce a large entropy and temperature change which is attractive for solid‐state cooling. We present the general considerations and review the experimental efforts to achieve large electrocaloric effect (ECE) in dielectrics. We show that by operating above the order‐disorder transitions, a large ECE can be achieved in a ferroelectric polymer.
Critical patients with the coronavirus disease 2019 (COVID-19), even those whose nucleic acid test results had turned negative and those receiving maximal medical support, have been noted to progress ...to irreversible fatal respiratory failure. Lung transplantation (LT) as the sole therapy for end-stage pulmonary fibrosis related to acute respiratory distress syndrome has been considered as the ultimate rescue therapy for these patients.
From February 10 to March 10, 2020, three male patients were urgently assessed and listed for transplantation. After conducting a full ethical review and after obtaining assent from the family of the patients, we performed three LT procedures for COVID-19 patients with illness durations of more than one month and extremely high sequential organ failure assessment scores.
Two of the three recipients survived post-LT and started participating in a rehabilitation program. Pearls of the LT team collaboration and perioperative logistics were summarized and continually improved. The pathological results of the explanted lungs were concordant with the critical clinical manifestation, and provided insight towards better understanding of the disease. Government health affair systems, virology detection tools, and modern communication technology all play key roles towards the survival of the patients and their rehabilitation.
LT can be performed in end-stage patients with respiratory failure due to COVID-19-related pulmonary fibrosis. If confirmed positive-turned-negative virology status without organ dysfunction that could contraindicate LT, LT provided the final option for these patients to avoid certain death, with proper protection of transplant surgeons and medical staffs. By ensuring instant seamless care for both patients and medical teams, the goal of reducing the mortality rate and salvaging the lives of patients with COVID-19 can be attained.
Background and Purpose
Cancer cells exhibit more dependence on iron and enhanced sensitivity to iron‐dependent, programmed cell death (ferroptosis) than normal cells. Quercetin exerts anti‐cancer ...effects, but the underlying molecular mechanism is largely unknown. In this study, we aimed to investigate the involvement of lysosome function and ferroptosis in the anti‐cancer potential of quercetin.
Experimental Approach
We used MTT assays and DNA content analysis to evaluate the cytotoxicity, colony formation assay to investigate cell proliferation, and flow cytometry and confocal microscopy to detect lysosomal acidification and protease enzyme activity. Western blotting, cell subfractionation, RT‐PCR and siRNA transfection were used to establish molecular mechanisms of action.
Key Results
Quercetin is known to promote p53‐independent cell death in various cancer cell lines. Although quercetin induces autophagy, genetic silencing of Atg7 fails to affect quercetin‐induced cell death. In contrast, both lysosome inhibitors and knockdown of the transcription factor EB can prevent quercetin‐induced cell death, suggesting the involvement of lysosome. Next, quercetin is found to induce lysosomal activation sequentially through nuclear translocation of EB and transcriptional activation of lysosomal genes. Notably, quercetin promoted lysosome‐dependent ferritin degradation and free iron release. This action and quercetin‐induced ROS generation synergistically resulted in lipid peroxidation and ferroptosis. Furthermore, Bid may link ferroptosis with apoptosis to cause cell death.
Conclusion and Implications
Quercetin induced EB‐mediated lysosome activation and increased ferritin degradation leading to ferroptosis and Bid‐involved apoptosis. Results from this study may expand our current knowledge about the mechanism of quercetin as an anti‐cancer agent.
To solve the inherent defects of laccase, the first iron single-atom anchored N-doped carbon material (Fe1@CN-20) as a laccase mimic was disclosed. The FeN4 structure of this material can well mimic ...the catalytic activity of laccase. Although Fe1@CN-20 has a lower metal content (2.9 wt%) than any previously reported laccase mimics, it exhibits kinetic constants comparable to those of laccase, as its Km (Michaelis constant) and Vmax (maximum rate) are 0.070 mM and 2.25 µM/min respectively, which are similar to those of laccase (0.078 mM, 2.49 µM/min). This catalyst displays excellent stability even under extreme pH (2–9), high temperature (100 °C), strong ionic strength (500 mM of NaCl), high ethanol concentration (volume ratio 40%) and long storage time (2 months). Additionally, it can be reused for at least 7 times with only a slight loss in activity. Therefore, this material has a much lower price and better stability and recyclability than laccase, which has been applied in the detection and degradation of a series of phenolic compounds. In the detection of adrenaline, Fe1@CN-20 achieved a detection limit of 1.3 µM, indicating it is more sensitive than laccase (3.9 µM).
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•The first iron-based laccase mimic is reported.•The metal content of Fe1@CN-20 (2.9 wt%) is the lowest of reported laccase mimics.•The sensor platform is set up for the determination of phenolic pollutants and adrenaline.•Fe1@CN-20 has comparabale kinetic constant with laccase (Km 70 vs 78 μM, Vm 2.25 vs 2.49 μM/min).•The LOD of Fe1@CN-20 (1.3 μM) for adrenaline is lower than laccase (3.9 μM).
A Co‐based heterogeneous catalyst supported on N,P co‐doped porous carbon (Co@NCP) is prepared via a facile in‐situ doping‐carbonization method. The Co@NCP composite features a large surface area, ...high pore volume, high‐density and strong basic sites. Furthermore, doping of P atoms can regulate the electronic density of Co. Therefore, Co@NCP exhibits good performance for the synthesis of quinoxalines from o‐nitroanilines and biomass‐derived diols under alkali‐free conditions.
Heterogeneous catalysis: The synthesis of a Co‐based heterogeneous catalyst supported on N,P co‐doped porous carbon (Co@NCP) by a facile in‐situ doping‐carbonization method is reported. Co@NCP exhibits good performance for the synthesis of quinoxalines from o‐nitroanilines and biomass‐derived diols under alkali‐free conditions.
The significance of fatty acid metabolism in cancer initiation and development is increasingly accepted by scientists and the public due to the high prevalence of overweight and obese individuals. ...Fatty acids have different turnovers in the body: Either breakdown into acetyl-CoA to aid ATP generation through catabolic metabolism or incorporation into triacylglycerol and phospholipid through anabolic metabolism. However, these two distinct pathways require a common initial step known as fatty acid activation. Long-chain acyl-CoA synthetases (ACSLs), which are responsible for activation of the most abundant long-chain fatty acids, are commonly deregulated in cancer. This deregulation is also associated with poor survival in patients with cancer. Fatty acids physiologically regulate ACSL expression, but cancer cells could hijack certain involved regulatory mechanisms to deregulate ACSLs. Among the five family isoforms, ACSL1 and ACSL4 are able to promote ungoverned cell growth, facilitate tumor invasion and evade programmed cell death, while ACSL3 may have relatively complex functions in different types of cancer. Notably, ACSL4 is also essential for the induction of ferroptosis (another form of programmed cell death) by facilitating arachidonic acid oxidation, which makes the enzyme a desirable cancer target. The present review thus evaluates the functions of deregulated ACSLs in cancer, the possible molecular mechanisms involved and the chemotherapeutic potentials to target ACSLs. A better understanding of the pathological effects of ACSLs in cancer and the involved molecular mechanisms will aid in delineating the exact role of fatty acid metabolism in cancer and designing precise cancer prevention and treatment strategies.
3D volumetric image processing has attracted increasing attention in the last decades, in which one major research area is to develop efficient lossless volumetric image compression techniques to ...better store and transmit such images with massive amount of information. In this work, we propose the first end-to-end optimized learning framework for losslessly compressing 3D volumetric data. Our approach builds upon a hierarchical compression scheme by additionally introducing the intra-slice auxiliary features and estimating the entropy model based on both intra-slice and inter-slice latent priors. Specifically, we first extract the hierarchical intra-slice auxiliary features through multi-scale feature extraction modules. Then, an Intra-slice and Inter-slice Conditional Entropy Coding module is proposed to fuse the intra-slice and inter-slice information from different scales as the context information. Based on such context information, we can predict the distributions for both intra-slice auxiliary features and the slice images. To further improve the lossless compression performance, we also introduce two new gating mechanisms called Intra-Gate and Inter-Gate to generate the optimal feature representations for better information fusion. Eventually, we can produce the bitstream for losslessly compressing volumetric images based on the estimated entropy model. Different from the existing lossless volumetric image codecs, our end-to-end optimized framework jointly learns both intra-slice auxiliary features at different scales for each slice and inter-slice latent features from previously encoded slices for better entropy estimation. The extensive experimental results indicate that our framework outperforms the state-of-the-art hand-crafted lossless volumetric image codecs ( e.g., JP3D) and the learning-based lossless image compression method on four volumetric image benchmarks for losslessly compressing both 3D Medical Images and Hyper-Spectral Images.
Cobalt nanoparticles embedded in N‐doped porous carbon (Co@CN) were prepared by the pyrolysis of bimetallic zeolitic imidazolate frameworks (BMZIFs) based on ZIF‐8 and ZIF‐67. The catalyst shows ...excellent catalytic efficiency in one‐pot selective oxidative cleavage of different linkages like β‐O‐4, a‐O‐4 and β‐1 in organosolv lignin and lignin model compounds in the presence of oxygen (ambient pressure) under mild conditions (383 K). Compared with traditional supported catalyst, the catalyst gives a highly hollow structure, which favored the adsorption of substrates and oxygen. The uniform cobalt nanoparticles surrounded by N‐doped graphitic structures and the strong electron transfer from graphitic nitrogen to Co NPs make it hard to be oxidized prior to use and higher catalytic reactivity. Moreover, the catalyst can be easily recovered by magnetic force after the reaction, and reused after reduction for five times without an obvious change in yields.
Selective oxidative dissociation of lignin: One‐pot Co@CN catalyzed selective oxidative dissociation of lignin and lignin model compounds with different linkages like β‐O‐4, α‐O‐4 and β‐1 under mild conditions without the assistance of any acid, base, ligand or noble metal has been reported.
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