Metal–organic frameworks (MOFs) have attracted enormous research interest as precursors/templates to prepare catalytic materials. However, the effect of structural isomerism of MOFs on the catalytic ...performance has rarely been studied. In this contribution, two topologically different Ce‐benzene tricarboxylate (Ce‐BTC) based on the same ligands and metal centers (viz., “MOF isomers”) are prepared and used as porous supports to load Pt nanoparticles (NPs), which shows distinct differences in porosities and loading behaviors of Pt. Strikingly, an irreversible framework transformation from tetragonal Ce‐BTC to monoclinic isomer is observed during water soaking treatment. The results give clear evidence that Pt/CeO2 derived from tetragonal Ce‐BTC inclines to produce more Pt0 and smaller Pt NPs, which eventually improve the catalytic performance for CO oxidation (T100 = 80 °C). In situ diffuse reflectance infrared Fourier transform spectroscopy analyses demonstrate that the adsorbed CO–Pt0 is the dominant intermediate for CO oxidation, rather than CO–Ptσ+ at the low temperature. Furthermore, MOF isomers based on the same structural units are also found in other Ln‐MOFs, such as Er‐BTC, Eu‐BTC, Y‐BTC, and Ce/Y‐BTC. Overall, this study affords a fundamental understanding of the effect of MOF structural isomers on the catalytic performance of the derived composites.
A facile method is devised for synthesizing two structural isomers of Ce‐benzene tricarboxylate (BTC) based on the same ligands and metal centers and then the metal–organic framework (MOF) isomers are used as porous supports to load Pt nanoparticles (NPs), which shows distinct differences in porosities, loading behaviors of Pt, and the catalytic performance in CO oxidation reaction.
Two-dimensional materials have been extensively studied in field-effect transistors (FETs). However, the performance of p-type FETs has lagged behind that of n-type, which limits the development of ...complementary logical circuits. Here, we investigate the electronic properties and transport performance of anisotropic monolayer GaSCl for p-type FETs through first-principles calculations. The anisotropic electronic properties of monolayer GaSCl result in excellent device performance. The p-type GaSCl FETs with 10 nm channel length have an on-state current of 2351 μA/μm for high-performance (HP) devices along the y direction and an on-state current of 992 μA/μm with an on/off ratio exceeding 107 for low-power (LP) applications along the x direction. In addition, the delay-time (τ) and power dissipation product of GaSCl FETs can fully meet the International Technology Roadmap for Semiconductors standards for HP and LP applications. Our work illustrates that monolayer GaSCl is a competitive p-type channel for next-generation devices.
Abstract
Metal–organic frameworks (MOFs) have attracted enormous research interest as precursors/templates to prepare catalytic materials. However, the effect of structural isomerism of MOFs on the ...catalytic performance has rarely been studied. In this contribution, two topologically different Ce‐benzene tricarboxylate (Ce‐BTC) based on the same ligands and metal centers (viz., “MOF isomers”) are prepared and used as porous supports to load Pt nanoparticles (NPs), which shows distinct differences in porosities and loading behaviors of Pt. Strikingly, an irreversible framework transformation from tetragonal Ce‐BTC to monoclinic isomer is observed during water soaking treatment. The results give clear evidence that Pt/CeO
2
derived from tetragonal Ce‐BTC inclines to produce more Pt
0
and smaller Pt NPs, which eventually improve the catalytic performance for CO oxidation (
T
100
=
80
°
C). In situ diffuse reflectance infrared Fourier transform spectroscopy analyses demonstrate that the adsorbed CO–Pt
0
is the dominant intermediate for CO oxidation, rather than CO–Pt
σ
+
at the low temperature. Furthermore, MOF isomers based on the same structural units are also found in other Ln‐MOFs, such as Er‐BTC, Eu‐BTC, Y‐BTC, and Ce/Y‐BTC. Overall, this study affords a fundamental understanding of the effect of MOF structural isomers on the catalytic performance of the derived composites.
Analyzing to operation mode of 10kV side with no load of 220kV main transformer, the shortcoming of the B-phase direct grounding operation type and a arrester parallel connecting with each phase on ...10kV side with no load of transformer is the best protecting method are pointed out. Through the demonstration to the generating conditions and calculation of capacitance transfer voltage, the right nominal voltage choosing methods for gapless arrester and the application possibility of gap zinc oxide arrester are presented, and the feasibility and effectiveness are proved by a operation example in this paper.
Due to the attenuation of underwater light, obtained images often suffer from low contrast, noise interference, and hazy content. In the field of underwater image enhancement, dark channel prior ...dehazing algorithms have achieved initial success, but they often do not take into account the correlation between different colors and depth. In this paper, we introduce the concept of depth-color correlation based on dark channel prior (DCP), additionally embedding a multi-scale dehazing and denoising module to effectively solve hazy content and noise interference. In particular, the depth-color correlation means that light from different color channels tends to have larger or smaller values as the depth increases. Therefore, we employ the three-bit indicator to represent the depth-color correlation and then further estimate the background light from the different color channels. Because the pyramid layers of the haze image contain varying degrees of noise, our multi-scale dehazing and denoising module decomposes the haze image into a Gaussian pyramid layer and a Laplacian pyramid layer, then dehazes and denoises them layer by layer. Thereafter, the pyramid layers are collapsed to obtain the enhanced image. Finally, in order to reduce the morphological artifacts, we employ the weighted guided filter. Results demonstrate that our method has superior enhancement capabilities compared to other state-of-the-art methods.
In this paper, the background, current research status and problems of separators for Li-ion batteries were reviewed first. Then a novel sandwich-like type of composite nonwoven separators was ...prepared to improve the performance of composite nonwoven Li-ion battery separators by combining SiO2/PVDF-HFP membranes with PVDF-HFP dipped PP nonwoven fabric. The physical and electrochemical properties of the composite separators were measured and analyzed. It is found that the mean pore size of the composite separators was in the range of 100 to 300nm with maximum pore size less than 2μm. The composite nonwoven-based separators possessed higher electrolyte uptake, stronger thermal stability, better wettability and lower interfacial resistance than the commercial PE separator. The batteries assembled with composite nonwoven separators showed stable cycling performance and improved rate performance. The composite nonwoven separators are expected to be a promising alternative to commercial PE separator.
For low target detection rate and inaccurate localization of most target detection networks in special underwater environments, we propose an underwater target detection algorithm with adaptive ...anchor frames. The adaptive anchor frame selection strategy differs from the traditional methods of manually designing anchor frames and obtaining anchor frames using the
K
-means clustering algorithm. Our method is based on the
K
-means clustering algorithm and consists of a grouping strategy and a dynamic
K
-value strategy. It can also automatically calculate the appropriate numbers of anchor boxes and layers of network output based on the characteristics of label data. And performance of the network is guaranteed while avoiding the computation caused by redundant structures. The simple but powerful RepVGG classification network is used as the backbone network. Therefore, the feature extraction capability of the network is enhanced and the detection performance of the network on fuzzy targets is improved. The experimental results show that the algorithm in this paper achieves better detection results in the underwater target detection task compared to other algorithms.
Cell-scaffold interactions have drawn significant attention in tissue engineering. In this study, we define a heterogeneous scaffold, which can be customized with respect to gradient strength, ...variable fiber diameter, and pore sizes. Heterogeneous scaffolds with ultrafine fibers (3–22 μm in diameter) can be printed via high-resolution melt electrowriting (MEW) using only one nozzle by adjusting the printing parameters. With precise control of the diameter of deposited fibers, complex patterns, such as a star, Tai Chi, and an eagle can be fabricated. Owing to the ultrafine fiber and heterogeneous design, cell-scaffold interaction and other occurrences were observed. The size of the diameter of the printed fiber is close to that of cells (tens of microns), smaller than those of conventional 3D printed scaffolds (100 μm or more), and cell adhesion is highly sensitive to variations in fiber diameter. By specifically arranging thick and thin fibers, cells can be induced to elongate in anticipated direction in a grid. In this study, cell alignment exhibited 4 different orientations in a single scaffold with 4 regions, separately. The scaffolds can also be heterogeneous in pore size. In this study, the proliferation speed of the cells in small pores is 3 times that of the cells in large pores. Moreover, various pore sizes and fibers can be integrated in one scaffold, allowing the control of cell growth to different statuses by adjusting the scaffold structures. This study generally presents a strategy for structure-induced cell growth for better simulating in vivo environment.
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•A new strategy was proposed to induce cell growth by adjusting structures of the scaffold.•A high resolution 3D printing method was developed to fabricate scaffold with heterogeneous structure.•Cells could be induced to elongate in expected directions by arrangement of thick and thin fibers in a single scaffold.
Chitin is the second-most abundant bioresource and widely used in the food, agricultural, biomedicine, and other industries. However, under the mutual restriction of extraction cost and environmental ...protection, it is relatively difficult to prepare chitin from natural sources by pure separation. The aim of this study is to extract chitin from fresh crab shell waste by decalcification (DC) and deproteinization (DP) using glutamic acid and alkaline protease. The optimum technological conditions for DC and DP were as follows: (1) 5% (w/v) glutamic acid solution was used as decalcifying agent, the ratio of material to liquid was 1:10 (m/v), and the ash content in chitin was 0.83 ± 0.027% after decalcification at 75° C for 12 h. (2) Using alkaline protease as enzymatic hydrolyzer, 1500 U of alkaline protease was added per gram of crab shell. Under the conditions of material-liquid ratio of 1:10 (m/v) and pH value of hydrolysate of 9.0, N content in chitin was 6.63 ± 0.10% after 6 h of enzymatic hydrolysis at 55° C. And the extraction rate of chitin was 92.25 ± 0.51%. As a decalcifying agent, glutamic acid could be recycled with a recovery rate of 77.42 ± 2.16%. Calcium carbonate in crab shell was converted into calcium hydrogen phosphate by calcium glutamate, and protein into amino acids and polypeptides, which could be used as feed additives. The “glutamic acid-enzymolysis” for extracting chitin from crab shell is a relatively closed process, which has the advantages of mild reaction, greatly reducing the discharge of three wastes and high comprehensive utilization rate of raw materials.
Underwater image enhancement has become an emerging research field in recent years. Among various research studies, methods based on deep learning have gained a foothold and gradually expanded their ...influences. Most of these methods need pairs of training images, but due to the complexity of the underwater environment, it is challenging for us to obtain such expected datasets. Considering this problem, this paper explores an underwater image enhancement approach based on the unsupervised training mode. Concretely, a generative adversarial network (GAN) without pairwise image training is proposed, called
UUGAN
. It aims to bring the visual effects of expert images to the raw images. Our model has three parts, broadly speaking. Firstly, a GAN network based on an encoder-decoder is constructed; and secondly, a bridge connection scheme with intermediate layer feature transition is proposed. Thirdly, a loss function with multi-input constraints is applied. To demonstrate the effectiveness of
UUGAN
, we evaluate it on several real-world and synthetic datasets and compare it with some excellent methods. In the qualitative and quantitative comparison experiments, our methods have achieved remarkable results.
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