In this article, a novel electrode of NiCo2S4@Ni(OH)2@polypyrrole nanotube arrays supported on nickel foam is fabricated through a facile method. Due to the superior electronic conductivity of the shell material polypyrrole (PPy) and the high pseudocapacitance of Ni(OH)2 together with the short ion transport pathway of NiCo2S4 nanotube arrays, the obtained core–shell NiCo2S4@Ni(OH)2@PPy shows an enhanced pseudocapacitive performance of about 9.1125 F cm−2 at a current density of 5 mA cm−2, which is nearly three times higher than that of the pristine NiCo2S4 sample (3.1875 F cm−2). The kinetic analysis reveals the diffusion controlled faradaic characteristic of NiCo2S4@Ni(OH)2@PPy (43.57% capacitive contribution). Moreover, an asymmetric supercapacitor is successfully assembled with NiCo2S4@Ni(OH)2@PPy as the positive electrode and active carbon (AC) as the negative electrode. The NiCo2S4@Ni(OH)2@PPy//AC device exhibits a relatively high energy density of 34.67 W h kg−1 at a power density of 120.127 W kg−1 and excellent cycling performance (about 98.87% capacitance retention over 30 000 cycles). The results show that the NiCo2S4@Ni(OH)2@PPy core–shell nanotube array is a promising electrode material for high performance supercapacitor applications.

Enhanced cycling stability of hierarchical NiCo2S4@Ni(OH)2@PPy core–shell nanotube arrays for aqueous asymmetric supercapacitors

Metal‐organic frameworks (MOFs), as new class of porous materials, are constructed by inorganic metal centers and bridging organic links. Recently, MOFs have been proved to be effective templates for preparing metal oxides with large surface areas and controlled shape by directly annealing in air. There are lots of reports about metal‐organic framework‐derived metal oxides as electrode materials for supercapacitors. Metal‐organic framework‐derived metal oxides can offer higher capacitances compared with that prepared by other synthetic methods, likely attribute to high surface areas and optimal pore sizes. However, at present, the specific capacitances of MOF‐derived metal oxides received are far lower than theoretical values, and the cycle numbers could not meet practical demands. Accordingly, much effort has been made to improve the performance by further modifying MOFs. Thus, this paper focused on the advances in performance optimization of MOF‐derived metal oxide as electrode materials for supercapacitors as follows: Dual metal MOF‐derived binary metal oxides. Metal oxides with 2 metal cations possess better electrical conductivity and richer redox active sites than single metal oxides. Metal‐organic framework‐derived carbon/metal oxide composites (MO@C) or graphene/MOF‐derived graphene/metal oxide composites. Doping carbon not only facilitate transportation of electrodes but also contribution to extra double‐layer capacitance. Hybrid MOF‐derived metal oxide composites (MO@MO). Metal oxide composites can produce some synergistic effects that the individuals cannot provide. Metal‐organic framework‐derived metal oxides with a hollow structure. The Hollow structure could shorten ion diffusion distance and adapt to volume expansion generated during the ion intercalated/extracted process.

A review of performance optimization of MOF‐derived metal oxide as electrode materials for supercapacitors

Design and applications of water-stable metal-organic frameworks: status and challenges

Cobalt based metal-organic frameworks and their derivatives for electrochemical energy conversion and storage

Two-dimensional (2D) mixed metal–organic frameworks (M-MOFs) have emerged as promising energy storage materials in the MOF family. Herein, we report the facile, room temperature synthesis of a Na/Zn-based bimetallic MOF, [NaZn2(μ2-BTC)2(μ2-O)2(Azopy)(H2O)2]n (1, where BTC = trimesic acid and Azopy = 4,4′-azopyridine), grown through a slow diffusion technique. The crystal structure of 1 reveals the ratio of Zn(II) to Na(I) metal ions to be 2 : 1, and the overall framework exhibits a 2D layered structure. In light of the poor conductivity of MOFs, and also to take full advantage of this 2D MOF for supercapacitor use, we assembled a unique robust heterostructure of 1 with another 2D material, i.e. reduced graphene oxide (2), using a simple-yet-effective ultra-sonication assisted approach. Electrochemical analyses reveal the notable specific capacitance (435.2 F g−1 at 1.6 A g−1) of the formed heterostructure (3), with exceptional cycling efficiency (no observed loss up to 4000 cycles in the absence of any binders). The obtained encouraging results were attributed to synergistically enhanced contributions from each participating 2D material and the formation of a robust heterostructure due to the proper stacking of the two different layered 2D materials. The results exceed those of related state-of-the-art structures and suggest the promising nomination of 2D MOFs and their heterostructures for application in the emerging world of next-generation supercapacitors.

Robust heterostructures of a bimetallic sodium–zinc metal–organic framework and reduced graphene oxide for high-performance supercapacitors

Developing a composite electrode containing both carbon and transition metal/metal oxide as the supercapacitor electrode can combine the merits and mitigate the shortcomings of both the components. Herein, we report a simple strategy to prepare the hybrid nanostructure of Co@Carbon and Co3O4@Carbon by pyrolysis a single MOFs precursor. Co-based MOFs (Co-BDC) nanosheets with morphology of regular parallelogram slice have been prepared by a bottom-up synthesis strategy. One-step pyrolysis of Co-BDC, produces a porous carbon layer incorporating well-dispersed Co and Co3O4 nanoparticles. The as-prepared cobalt-carbon composites exhibit the thin layer morphology and large specific surface area with hierarchical porosity. These features significantly improve the ion-accessible surface area for charge storage and shorten the ion transport length in thin dimension, thus contributing to a high specific capacitance. Improved capacitance performance was successfully realized for the asymmetric supercapacitors (ASCs) (Co@Carbon//Co3O4@Carbon), better than those of the symmetric supercapacitors (SSCs) based on Co@Carbon and Co3O4@Carbon materials (i.e., Co@Carbon//Co@Carbon and Co3O4@Carbon//Co3O4@Carbon). The working voltage of the ASCs can be extended to 1.5 V and show a remarkable high power capability in aqueous electrolyte. This work provides a controllable strategy for nanostructured carbon-metal and carbon-metal oxide composite electrodes from a single precursor.

/pdf/co-carbon-and-co-3-o-4-carbon-nanocomposites-derived-from-a-3hrp48w6bu.pdf

Co@Carbon and Co 3 O 4 @Carbon nanocomposites derived from a single MOF for supercapacitors

Metal-organic frameworks (MOFs) show possibilities to be potential candidates for proton exchange membranes (PEMs). However, the poor flexibility and processability of MOFs due to their crystalline nature limit their applications significantly. An efficient approach to overcome this limitation is to combine MOFs with polymers. In this work, novel lightweight and flexible Ni-MOFs/polyacrylonitrile nanofibers were fabricated by electrospinning. The nanofibers consisted of one-dimensional proton conduction channels for imidazole and show enhanced proton conductivity. A proton conductivity of 6.04 × 10-5 Scm-1 was achieved at 363 K and 90% RH. Furthermore, the proton transport dynamics of the fibers were investigated using the AC impedance technique.

Enhanced proton conduction of imidazole localized in one-dimensional Ni-metal-organic framework nanofibers

Enhanced ionic conductivity of ionic liquid confined in UiO-67 membrane at low humidity

Gastric cancer (GC) ranks as the most common gastrointestinal cancer and is among the leading causes of cancer death worldwide. Glaucocalyxin A (GLA), an entkauranoid diterpene isolated from Rab-dosia japonica var., possesses various bioactivities. To date, the data on the effect of GLA on GC are still minimal, and the molecular mechanisms remain largely unknown. Herein, we found that GLA could significantly inhibit the proliferation, cell adhesion, and invasion of HGT-1, SNU-1, SNU-6, and NCI-N87 GC cells in a dose-dependent manner. GLA enhanced the apoptosis of the GC cells as evidenced by the increased caspase-3 activity and the elevated levels of cleaved caspase-3 and cleaved PARP in GC cells in the presence of GLA. We then showed that the downregulation of Murine Double Minute Clone 2 (MDM2) and Ring Finger Protein 6 (RNF6) by GLA was implicated in the GLA-induced inhibition of the GC cells. Furthermore, MDM2 and RNF6 were identified as the targets of miR-3658 that was downregulated in the GC cells and upregulated by GLA. Moreover, it was shown that miR-3658 was hypermethylated in the GC cells, and GLA could rescue the expression of miR-3658 via demethylation by abrogating EZH2-mediated epigenetic silencing. In addition to the miR-3658-MDM2/RNF6 regulatory axis, activation of the SMG1-UPF mRNA decay pathway contributed to the downregulation of MDM2 and RNF6 by GLA in the GC cells. The inhibitory effect of GLA on gastric cancer and the expression of MDM2 and RNF6 was also validated in in vivo study. Our findings suggest that has the therapeutic potential for GC by downregulating oncogenes via posttranscriptional regulation.

https://www.frontiersin.org/articles/10.3389/fonc.2022.871169/pdf

Glaucocalyxin A Inhibits the Malignancies of Gastric Cancer Cells by Downregulating MDM2 and RNF6 via MiR-3658 and the SMG1-UPF mRNA Decay Pathway

BACKGROUND
Low-dose CT (LDCT) images usually contain serious noise and artifacts, which weaken the readability of the image.


OBJECTIVE
To solve this problem, we propose a compound feature attention network with edge enhancement for LDCT denoising (CFAN-Net), which consists of an edge-enhanced module and a proposed compound feature attention block (CFAB).


METHODS
The edge enhancement module extracts edge details with the trainable Sobel convolution. CFAB consists of an interactive feature learning module (IFLM), a multi-scale feature fusion module (MFFM), and a joint attention module (JAB), which removes noise from LDCT images in a coarse-to-fine manner. First, in IFLM, the noise is initially removed by cross-latitude interactive judgment learning. Second, in MFFM, multi-scale and pixel attention are integrated to explore fine noise removal. Finally, in JAB, we focus on key information, extract useful features, and improve the efficiency of network learning. To construct a high-quality image, we repeat the above operation by cascading CFAB.


RESULTS
By applying CFAN-Net to process the 2016 NIH AAPM-Mayo LDCT challenge test dataset, experiments show that the peak signal-to-noise ratio value is 33.9692 and the structural similarity value is 0.9198.


CONCLUSIONS
Compared with several existing LDCT denoising algorithms, CFAN-Net effectively preserves the texture of CT images while removing noise and artifacts.

Compound feature attention network with edge enhancement for low-dose CT denoising.

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