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81.
In this paper, we describe a numerical model to simulate the evolution in time of the hydrodynamics of water storage tanks, with particular emphasis on the time evolution of chlorine concentration. The mathematical model contains several ingredients particularly designed for this problem, namely, a boundary condition to model falling jets on free surfaces, an arbitrary Lagrangian–Eulerian formulation to account for the motion of the free surface because of demand and supply of water, and a coupling of the hydrodynamics with a convection–diffusion–reaction equation modeling the time evolution of chlorine. From the numerical point of view, the equations resulting from the mathematical model are approximated using a finite element formulation, with linear continuous interpolations on tetrahedra for all the unknowns. To make it possible, and also to be able to deal with convection‐dominated flows, a stabilized formulation is used. In order to capture the sharp gradients present in the chlorine concentration, particularly near the injection zone, a discontinuity capturing technique is employed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
82.
Jens Noack Nataliya Roznyatovskaya Tatjana Herr Peter Fischer 《Angewandte Chemie (International ed. in English)》2015,54(34):9776-9809
The development of various redox‐flow batteries for the storage of fluctuating renewable energy has intensified in recent years because of their peculiar ability to be scaled separately in terms of energy and power, and therefore potentially to reduce the costs of energy storage. This has resulted in a considerable increase in the number of publications on redox‐flow batteries. This was a motivation to present a comprehensive and critical overview of the features of this type of batteries, focusing mainly on the chemistry of electrolytes and introducing a thorough systematic classification to reveal their potential for future development. 相似文献
83.
Liaoliao Wang Meixiang Cen Dr. Sherif A. El-Khodary Dr. K. Ramachandran Jinning Huang Dr. Yingxue Cui Prof. Dr. Dickon H. L. Ng Prof. Dr. Chuan Wang Prof. Dr. Jiabiao Lian 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(68):e202202358
Surface oxygen functionalities (particularly C−O configuration) in carbon materials have negative influence on their electrical conductivity and Na+ storage performance. Herein, we propose a concept from surface chemistry to regulate the oxygen configuration in hierarchically porous carbon nanosheets (HPCNS). It is demonstrated that the C−O/C=O ratio in HPCNS reduces from 1.49 to 0.43 and its graphitization degree increases by increasing the carbonization temperature under a reduction atmosphere. Remarkably, such high graphitization degree and low C−O content of the HPCNS-800 are favorable for promoting its electron/ion transfer kinetics, thus endowing it with high-rate (323.6 mAh g−1 at 0.05 A g−1 and 138.5 mAh g−1 at 20.0 A g−1) and durable (96 % capacity retention over 5700 cycles at 10.0 A g−1) Na+ storage performance. This work permits the optimization of heteroatom configurations in carbon for superior Na+ storage. 相似文献
84.
Natural cellulose substances have been proven to be ideal structural templates and scaffolds for the fabrication of artificial functional materials with designed structures, psychochemical properties and functionalities. They possess unique hierarchically porous network structures with flexible, biocompatible, and environmental characteristics, exhibiting great potentials in the preparation of energy-related materials. This minireview summarizes natural cellulose-based materials that are used in batteries, supercapacitors, photocatalytic hydrogen generation, photoelectrochemical cells, and solar cells. When natural cellulose substances are employed as the structural template or carbon sources of energy materials, the three-dimensional porous interwoven structures are perfectly replicated, leading to the enhanced performances of the resultant materials. Benefiting from the mechanical strengths of natural cellulose substances, wearable, portable, free-standing, and flexible materials for energy storage and conversion are easily obtained by using natural cellulose substances as the substrates. 相似文献
85.
Junxiong Wu Prof. Francesco Ciucci Prof. Jang-Kyo Kim 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(29):6296-6319
The rapid development of electrochemical energy storage systems requires new electrode materials with high performance. As a two-dimensional material, molybdenum disulfide (MoS2) has attracted increasing interest in energy storage applications due to its layered structure, tunable physical and chemical properties, and high capacity. In this review, the atomic structures and properties of different phases of MoS2 are first introduced. Then, typical synthetic methods for MoS2 and MoS2-based composites are presented. Furthermore, the recent progress in the design of diverse MoS2-based micro/nanostructures for rechargeable batteries, including lithium-ion, lithium-sulfur, sodium-ion, potassium-ion, and multivalent-ion batteries, is overviewed. Additionally, the roles of advanced in situ/operando techniques and theoretical calculations in elucidating fundamental insights into the structural and electrochemical processes taking place in these materials during battery operation are illustrated. Finally, a perspective is given on how the properties of MoS2-based electrode materials are further improved and how they can find widespread application in the next-generation electrochemical energy-storage systems. 相似文献
86.
Nesrine Mechi Ismahen Ben Khemis Houcine Dhaou Slim Zghal Abdelmottaleb Ben Lamine 《Chinese Journal of Physics (Taipei)》2018,56(2):449-467
The Mg50Ni45Cr5 alloy for hydrogen storage is prepared by mechanical alloying. First, using the X-ray diffraction (XRD) and the scanning electron microscopy (SEM) we examine the morphology and the structure of the substrate. The obtained results highlight the effectiveness of this alloy in loading hydrogen as it is a nanocrystalline and a ductile one. Second, we attempt to justify these expectations using the statistical physic, precisely the model monolayer with two levels of energy, in modeling a hydrogen absorption and desorption isotherms on Mg50Ni45Cr5 alloy at four temperatures T?=?275?K, T?=?300?K, T?=?325?K and T?=?350?K. The model has six physicochemical parameters deduced from the fitting of the isotherms, they are divided by two categories of steric and energetic parameters. Thanks to these parameters we compare the absorption and desorption processes, in order to highlight the hysteresis phenomenon encountered during the hydrogen sorption. 相似文献
87.
Wan Su Jung Hanui Ye Mateen Fahad Jun Bae Lee Su Ji Kim Jihui Jang 《Liquid crystals》2016,43(10):1495-1502
In this study, we postulated that the optical retardation magnitude could be used to evaluate the stability of the LC phase through the Mueller matrix polarimeter method in LC emulsion. In addition, we found that the increase of cetearyl alcohol concentration induced the more periodic dense lattice structure in crystalline phase of LC lamellae and the sorbitan olivate was relatively more responsible for higher ordering in LC phase compared to C12–20 alkyl glucoside in terms of molecular parallel packing on the basis of the optical retardation magnitude. Furthermore, it was confirmed that the LC emulsion had higher skin barrier function owing to lower TEWL and higher reflectance than ordinary emulsion on human skin and maintained a uniform phase without phase separation for 8 weeks. 相似文献
88.
Dr. Meaghan M. Deegan Michael R. Dworzak Aeri J. Gosselin Kyle J. Korman Prof. Dr. Eric D. Bloch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(14):4531-4547
Molecules with permanent porosity in the solid state have been studied for decades. Porosity in these systems is governed by intrinsic pore space, as in cages or macrocycles, and extrinsic void space, created through loose, intermolecular solid-state packing. The development of permanently porous molecular materials, especially cages with organic or metal–organic composition, has seen increased interest over the past decade, and as such, incredibly high surface areas have been reported for these solids. Despite this, examples of these materials being explored for gas storage applications are relatively limited. This minireview outlines existing molecular systems that have been investigated for gas storage and highlights strategies that have been used to understand adsorption mechanisms in porous molecular materials. 相似文献
89.
《Electroanalysis》2018,30(2):230-237
This work proposes the use of an electronic tongue based on flow injection coulometry for the rapid determination of the antioxidant capacity of fresh lettuce. The e‐tongue consisted of a series of 16 porous carbon electrodes, each poised at a fixed potential from +100 to +850 mV. Each injection leaded to a characteristic hydrodynamic voltammogram, whose profile reflects the composition of antioxidants. The correlation between the peak area recorded by each sensor and the 1,1‐Diphenyl‐2‐picryl‐hydrazyl (DPPH) assay was maximum ín the range of potentials between +400 and 750 mV (R2>0.97). Accordingly, the charge measured provided a direct and simple index of the antioxidant capacity. The practical utility of such index was initially demonstrated by determining the best extraction conditions. This consisted in freeze‐drying of lettuce followed by methanolic extraction. Later, the e‐tongue was used to evaluate the effect of storage (one week at 5 °C) on lettuce. The e‐tongue revealed that lettuce lost up to 25 % of their initial antioxidant activity during storage. However, when lettuce samples were pre‐treated with fast cooling or vacuum cooling, the decrease of the antioxidant index was limited to 14 and 15 %. Overall, the e‐tongue is a rapid, simple and sensitive method for the determination of the antioxidant capacity of fresh lettuce samples. Indirectly, these findings suggest also that lettuce may serve as potential dietary sources of natural phenolic antioxidants. 相似文献
90.
Liping Liao Bing Wu Dr. Evgeniya Kovalska Dr. Vlastimil Mazánek Dr. Martin Veselý Ivo Marek Lucie Spejchalová Prof. Dr. Zdeněk Sofer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(52):13235-13241
The intercalation of cations into layered-structure electrode materials has long been studied in depth for energy storage applications. In particular, Li+-, Na+-, and K+-based cation transport in energy storage devices such as batteries and electrochemical capacitors is closely related to the capacitance behavior. We have exploited different sizes of cations from aqueous salt electrolytes intercalating into a layered Nb2CTx electrode in a supercapacitor for the first time. As a result, we have demonstrated that capacitive performance was dependent on cation intercalation behavior. The interlayer spacing expansion of the electrode material can be observed in Li2SO4, Na2SO4, and K2SO4 electrolytes with d-spacing. Additionally, our results showed that the Nb2CTx electrode exhibited higher electrochemical performance in the presence of Li2SO4 than in that of Na2SO4 and K2SO4. This is partly because the smaller-sized Li+ transports quickly and intercalates between the layers of Nb2CTx easily. Poor ion transport in the Na2SO4 electrolyte limited the electrode capacitance and presented the lowest electrochemical performance, although the cation radius follows Li+>Na+>K+. Our experimental studies provide direct evidence for the intercalation mechanism of Li+, Na+, and K+ on the 2D layered Nb2CTx electrode, which provides a new path for exploring the relationship between intercalated cations and other MXene electrodes. 相似文献