Material Loading Research Articles

Assessing drivers of estuarine pH: A comparative analysis of the continental U.S.A.'s two largest estuaries

AbstractIn estuaries, local processes such as changing material loads from the watershed and complex circulation create dynamic environments with respect to ecosystem metabolism and carbonate chemistry that can strongly modulate impacts of global atmospheric CO2 increases on estuarine pH. Long‐term (> 20 yr) surface water pH records from the USA's two largest estuaries, Chesapeake Bay (CB) and Neuse River Estuary‐Pamlico Sound (NRE‐PS) were examined to understand the relative importance of atmospheric forcing vs. local processes in controlling pH. At the estuaries’ heads, pH increases in CB and decreases in NRE‐PS were driven primarily by changing ratios of river alkalinity to dissolved inorganic carbon concentrations. In upper reaches of CB and middle reaches of the NRE‐PS, pH increases were associated with increases in phytoplankton biomass. There was no significant pH change in the lower NRE‐PS and only the polyhaline CB showed a pH decline consistent with ocean acidification. In both estuaries, interannual pH variability showed robust, positive correlations with chlorophyll a (Chl a) during the spring in mid to lower estuarine regions indicative of strong control by net phytoplankton production. During summer and fall, Chl a and pH negatively correlated in lower regions of both estuaries, given a shift toward heterotrophy driven by changes in phytoplankton community structure and increases in the load ratio of dissolved inorganic nitrogen to organic carbon. Tropical cyclones episodically depressed pH due to vertical mixing of CO2 rich bottom waters and post‐storm terrestrial organic matter loading. Local processes we highlight represent a significant challenge for predicting future estuarine pH.

The Effect of Repeated Review of Course Content on Medium- and Long-Term Retention in an Elective Veterinary Cardiology Course.

Assessment in veterinary medicine is challenging given the high volume of material and high cognitive load. Differing opinions exist regarding the utility of comprehensive final examinations in veterinary courses. A mixed-methods prospective randomized trial was undertaken with veterinary students (n = 47) in an elective cardiology course. All students received identical content, which was presented through weekly in-class lectures (eight total lessons). They were given access to four different formats of study aids and completed quizzes of content knowledge within 1 week of each lesson. For the cumulative final examination (post-test), students were explicitly instructed to study only for four out of the eight lessons. Students then completed a delayed post-test 3-6 months after completion of the course. Quantitative and qualitative data were collected in the form of in-depth pre- and post-course surveys. Overall, studying a particular lesson for the post-test resulted in higher scores for six out of eight lessons in the post-test (p < .05) but did not result in significantly higher scores for any lesson in the delayed post-test. Time spent studying for individual quizzes, as well as other measures of study habits, decreased significantly throughout the semester. Among study aids, student preference was highest for instructor-provided graphic organizers, and this preference persisted across the semester with a shift away from instructor-provided outlines over time (p = .043). Free-text survey responses showed that students had realistic expectations for the impact of studying for the post-test and appreciated exposure to a variety of study aid formats. In an elective veterinary cardiology course, review of material prior to a cumulative final examination led to improved short-term performance but no difference in retention 3-6 months later.

On the Static Instability of FG-GNP-Reinforced Composite Cylindrical Shells Under Thermo-Mechanical Loading

The nonlinear buckling response of laminated composite cylindrical shells reinforced with graphene nanoplatelets (GNPs) is studied in this paper. The functionally graded (FG) shell reinforced by GNPs is analytically studied under external pressure and uniform temperature rise loadings. It is also assumed that the GNP-reinforced laminated composite shell is in contact with an elastic foundation. Various types of profiles are employed for the GNP distribution patterns in the shell thickness including 10 nanocomposite layers. The nonlinear strain-displacement relations of the shallow cylindrical panel are established utilizing the third-order shear deformation shell theory. Governing equilibrium equations of the laminated GNP-reinforced composite shell are formulated employing the principle of virtual displacement. The coupled system of nonlinear differential equations is solved analytically for the hinged–hinged and fixed–fixed boundaries of the shell using a perturbation-based technique. Correctness of presented formulations and obtained solutions is proved by comparisons with results from previous studies for an isotropic cylindrical shell. Novel numerical results reveal that the material properties, geometrical characteristics and load parameters significantly affect on the buckling behavior of laminated composite cylindrical shells.

Hydrothermal synthesis of Ni,Co hydroxide nanosheet array on vertically suspended Ni foam for high performance supercapacitors

Ni(OH)2 have attracted great attention as pseudocapacitor electrode materials due to its high theoretical capacitance. However, the intrinsic disadvantaged in low electronic conductivity and sluggish ion diffusion kinetics of Ni(OH)2 limit its performance and practical application. Herein, we report a simple hydrothermal method to synthesize Co doped Ni(OH)2 and NiOOH array structure on vertical hanging Ni foam. Compared with traditional hydrothermal methods, vertical hanging Ni foam provide sufficient reaction sites and ensure fully growth of array structure, leading to large mass loading of active materials. The array structure and the wide interlayer spacing due to interlayer embedded CH3COO− together build an effcient ion diffusion path. Morevoer, strong electron exchange between Ni(OH)2 or NiOOH and Ni provide high electrical conductivity at the interface, forming the fast and complete electron transport channel inside the electrode. As a result of robust electrochemical kinetics, NiCoLDH@vNF-12 shows a high capacitive and outstanding rate performance of 952.9 C g−1 at 1 A g−1 and 660.0 C g−1 even at 50 A g−1.

In Situ Synthesis Method of Approaching High Surface Capacity Sulfur and the Role of Cobalt Sulfide as Lithium–Sulfur Battery Materials

Lithium–sulfur batteries (Li–S) are potentially applicable in electrification and the replacement of fossil fuels due to the high energy density and the economy of sulfur. However, effectively an insulator, sulfur is known to suffer from inert electrochemical and poor conductivity. By synthetically incorporating conductive, low‐dimensional carbonaceous composites acting as both containment hosts and catalysts to active materials, this work entails an effective and straightforward materials engineering approach in fundamentally remodeling active materials utilization and activation. This synthetic‐based approach highlights direct processing capabilities than traditional thermal infusion processes without compromising performance and addresses the low activation, poor conductivity as well as alleviating side reactions due to polysulfide species. Motivated by recent efforts in excellent catalytic properties of cobalt sulfide (CoS)‐based materials, in this work, high‐performance CoS‐based carbonaceous composites are designed and employed, alleviating side reactions. These sulfide‐based catalysts are further elucidated in their role in facilitating charge/discharge of active materials, and assessed on practical polysulfide and side reaction alleviation with respect to various discharge/charge states. Proof‐of‐concept devices demonstrate the following performance highlights: 1) high‐performance stability, 2) strong polysulfide adsorption capability and kinetic characteristics, 3) large and workable areal capacity, and active materials loading.

Optimizing coupling effect of confined FeNi nanoalloys within graphitic carbon nanofibers to improve photothermal energy conversion efficiency for solar water purification

Sustainable and energy-efficient water purification by harnessing solar energy is critical to tackling the challenges of water scarcity and the on-going water pollution crisis. Nevertheless, the biggest challenge to the practical deployment of solar-driven water purification, however, continues to be the poor solar evaporation efficiency of materials. Herein, FeNi nanoalloys encapsulated in graphitic carbon nanofibers (FeNi3/CNF) using Prussian blue analogue (PBAs) derivatives were fabricated using electrospinning and carbonization. The PBAs metal precursors play a critical role in encapsulating and safeguarding the FeNi alloy nanostructures from oxidation and agglomeration challenges. Furthermore, the synergistic effects between the non-noble hybrid plasmonic nanoalloys and graphitic CNFs can be constructed and optimized from the mass loading of PBAs precursor. Benefiting from the broad solar absorption band, high specific surface area, abundant micro-mesopores, and well-organized interlayer channel, the resultant 2D FeNi3/CNF solar evaporator demonstrates an efficient water evaporation rate of 1.51 kg m-2h−1 with an outstanding solar evaporation efficiency of 93.3 % under one sun irradiation, among the best values reported thus far. Impressively, the resultant 2D FeNi3/CNF solar evaporator can be constructed using only 0.02 kg m−2 loading of photothermal materials without compromising evaporation performance, which highlights its cost-efficiency in the practical application. Furthermore, the desalinated water meets the drinking standards of the World Health Organization (WHO) with an efficient 99 % separation of multiple organic industrial dye pollutants. Hence, this work demonstrates an efficient cost-effective approach to novel non-noble plasmonic alloy-based metal–carbon composites for enhanced solar-driven interfacial evaporation and wastewater purification.

ОПРЕДЕЛЕНИЕ КОЭФФИЦИЕНТА ЗАГРУЗКИ МАТЕРИАЛА В КАМЕРЕ ПОМОЛА ШАРОВОЙ БАРАБАННОЙ МЕЛЬНИЦЫ

The predominant application of ball drum mills in industrial enterprises for the comminution process of various materials, which is one of the most energy-intensive basic technological processes, is demonstrated in this scientific article. As one of the parameters that can enhance the efficiency of the comminution process, the rational quantitative ratio of grinding bodies to the material being ground is noted. To calculate the material loading coefficient in the grinding chamber, the feasibility of developing a mathematical description is shown. This allows to determine the change in the area of gaps between grinding bodies in a cross-sectional plane perpendicular to the longitudinal axis of the mill's body, as the rotational frequency changes. A mathematical description is obtained to determine the area of the ball-material load in the cross-sectional plane of the grinding chamber during the static state of the mill's body and at different rotational frequencies. Using this mathematical description, research on the change in the area occupied by the ball-material load in the transverse section of the grinding chamber during the transition of the mill's body from the static state to the operating state is conducted. Regularities of its changes for an industrial-sized mill are determined. At different values of the filling coefficient of grinding bodies, it is established that the transition of the mill's body from static to operating state leads to an increase in the area of the transverse section of the ball-material load by an amount close to 17 %. An expression is proposed to determine the material loading coefficient in the grinding chamber corresponding to its operating rotational frequency.

Laser-induced oxygen vacancy defect Mn7O13·5H2O as binder-free cathode for high performance all-in-one zinc-ion battery

Reachable Zinc ion batteries (ZIBs) are regarded as promising large scale energy storge systems because of their advantages of high safety, high energy density (high volumetric capacity), and economic benefits. However, ZIBs suffer from of lack of suitable cathode materials with high capacity and long stability of circulation. In addition, conventional coating process to prepare cathode with binder (PVDF/PTFE et al.) will not only reduce active material loading but also hinder ion transmission. Hence, a simple binder-free cathode prepare process was proposed. We use laser irradiation the Mn7O13·5H2O/graphene oxide cathode. The laser irradiation will induce vacancy defect in the Mn7O13·5H2O, leading to more active contact sites. Finally, the prepared materials achieve an ultra-high specific capacity of 411.6 mAh g−1 (0.2 A g−1), an excellent rate performance (176.3 mAh g−1 at a current density of 5 A g−1), and a satisfactory capacity retention rate of 90.1% after long 3500 cycles at 2 A g−1. The assembled all-in-one architecture battery has a fair specific capacity of 177.3 mAh g−1 at the current density of 2 A g−1. This work opens up a new horizon for conveniently preparing binder-free cathode materials with defects for high energy density and long cycle life.

Tunable and efficient electromagnetic wave absorption of carbon material modulating magnetic ionic polymer-based composites

Developing the miniaturization and intellectualization of carbon-based chips and electronic devices is extremely desirable but remains hampered by electromagnetic interference. Magnetic ionic polymer (MIP) holds great promise for electromagnetic-absorbing material in the field of electromagnetic reliability of communication equipment due to its dielectric loss and magnetic loss are obviously higher than other commonly polymers. However, it remains a formidable challenge for MIP to achieve satisfactory absorption of electromagnetic wave (EMW). Herein, we achieved the excellent EMW absorbing performance of the poly[1-allyl-3-vinylimidazolium tetrachloroferrate]/carbon nanotube/reduced graphene oxide (P[AVIm][FeCl4]/CNT/rGO) composites when the only carbon materials loading of 10 wt%. Most strikingly, the effective absorption bandwidth (EAB) is as wide as 5.63 GHz, the lowest reflection loss can reach up to −51.05 dB with the absorber thickness of 2.2 mm. The enhancement in microwave absorption efficiency of P[AVIm][FeCl4]/CNT/rGO composites are arisen from the synergistic effects in its unique multicomponent heterostructure interface, which causes multiple reflections and strong conduction loss, further suitable impedance matching ratio and favorable attenuation ability. This work proposes a new perspective approach and fundamental absorption mechanisms to realize excellent performance EMW absorption.

Robust and adhesive double-solvent phase change hydrogel with reversible transparency and shape memory for thermal management and information encryption

The excellent energy storage capacity of solid–liquid phase change materials has attracted considerable attention, but the vulnerability to leakage limits their applications. Therefore, the development of composite phase change materials has become a hot research topic in recent years. Therefore, a double-solvent (DS) phase change hydrogel (PCH) prepared by random copolymerization of acrylic acid (AA) and hydroxyethyl methacrylate (HEMA) with water and polyethylene glycol (PEG) as solvents was proposed. The phase transition enthalpies of melting and crystallization of the gel reached 116.2 J·g−1 and 113.5 J·g−1, respectively. PCH exhibits good morphological stability while storing thermal energy, which can effectively encapsulate phase change materials without leakage at high temperatures and be recyclable. PEG is used as both solvent and phase change part and the prepared gel reveals a high phase change material loading rate (76.2%), high breaking stress (4.7 MPa) and excellent compression resistance (1.2 MPa), superior to existing counterparts. The presence of a small amount of water in the system endows the gel with certain flexibility. Moreover, due to the solid–liquid phase transition behavior of PEG during temperature changes, PCHs possesses reversible adhesion and transparency, as well as shape memory properties. In addition, its low thermal conductivity and high energy storage efficiency make it perform well in the field of infrared stealth.

A sulfur cathode design strategy for polysulfide restrictions and kinetic enhancements in Li-S batteries through oxidative chemical vapor deposition

Lithium-sulfur (Li-S) batteries offer a promising solution for achieving high-density and low-cost energy storage devices. However, the practical utilization of Li-S batteries is hindered by the main bottleneck of polysulfides transport from the cathode to the electrolyte and anode, which leads to the detrimental degradation of the electrolyte and non-uniform microstructure evolution on the anode, ultimately resulting in rapid capacity fading. To overcome this limitation, we propose a groundbreaking mitigation strategy that leverages the oxidative chemical vapor deposition (oCVD) technique to limit the shuttling of polysulfides in the cathode. This gas-phase approach is unique in that highly conducting and conformal polymer coating entirely eliminates the use of traditional binders in the cathode while enhancing the kinetic conditions of the sulfur conversion and inhibiting the shuttling of polysulfides during battery operation. Complementary experimental and theoretical investigations identify that polysulfides are physically and chemically confined in the cathode region. The sulfur cathode manufactured using this approach demonstrates high active material loading (90 wt%), a high sulfur utilization ratio of 84.4% (∼1413 mAh g−1 at 0.1 C), and capacity retention of 85% after 300 cycles (∼810 mAh g−1) at 0.5 C. The pouch cell also showcases a high specific energy of up to 202 Wh kg−1 with a low electrolyte/sulfur ratio of 4.55, proving the immense potential for practical applications.

Interfacial interaction of controlled poly(ether-imide) (PEI) - titanium dioxide-based nanocomposites

The nanocomposites were produced using a melt-blending process and poly (ether imide) (PEI) reinforced with bioactive titanium dioxide (TiO2) nanoparticles. Fourier Transformed Infrared Spectroscopy (FTIR), Microstructural analysis, Differential Scanning Calorimetric (DSC) of the generated interfacial interaction materials is exploited. The prominent peaks in FTIR measurement are found to be sensitive to TiO2 content. The peaks shift towards higher wavelength as a consequence of TiO2 addition. Polymer matrix and filler in the FTIR spectrum have a significant hydrogen bonding coupling. The uniform dispersion of TiO2 nanoparticles within the polymer was studied without surface treatment or polymer functionalization. It has been observed that with increasing TiO2 concentration, the matrix's crystallisation rate was altered from promotion to retardation, while its crystalline structure remained unaffected. TiO2 addition gradually lowers the glass transition temperature (Tg) of poly (ether imide) composite. The polymer matrix was concurrently made stiffer, stronger, and tougher by the nanoparticles, and the best characteristics were attained at 5.0 wt% of TiO2. Even though the nanocomposites had improved thermal stability and glass transition temperatures, they also showed less water absorption. The analyses are utilised to determine the type of nanoparticle and the consistency of the composite material's loading.

Active physics-constrained dictionary learning to diagnose nozzle conditions in fused filament fabrication process

Fused filament fabrication (FFF) is a versatile additive manufacturing process that can be used to fabricate parts with different materials such as polymers, biomaterials, composites, and ceramics. One of the main challenges in its applications however is the variability of build qualities, which is largely caused by the variations of process parameters and machine conditions. The sensing system for in-situ process monitoring is limited by the available bandwidth for data transmission and the cost of data processing and analysis. Recently a physics-constrained dictionary learning (PCDL) method was developed to improve the sensing efficiency with optimized dictionaries for simultaneous sparse coding and classification. In this work, a new approach of active PCDL is proposed to further improve the sensing efficiency by incorporating an active learning scheme. The active PCDL approach is demonstrated with acoustic emission signals collected in the FFF process to identify different nozzle conditions, such as normal operating condition, material loading, extruder blockage, and running out of material, with a limited amount of data collection. The original signal can also be reconstructed simultaneously.

Fatigue fracture quantification in brittle cementitious materials using acoustic emission testing and digital image correlation

Fatigue loading in brittle materials introduces damage at the micro-scale. These micro-fractures can accumulate and cause a significant reduction in material stiffness or even lead to structural failure. Deformation-based monitoring techniques can be inadequate when detecting damage at the micro-level. Hence, here is where advanced non-destructive testing (NDT) methods such as acoustic emission testing (AET) and digital image correlation (DIC) can provide a significant improvement in quantifying fatigue damage. The paper aims to combine AET and DIC for advanced fatigue damage analysis on brittle cementitious mortars. Cylindrical samples with three different sizes are subjected to fatigue loading in a Brazilian splitting test. The damage advancement quantified from cumulative AE event count and energy analysis showed a good correlation with the tensile deformation measurement of the DIC. It was observed that for low cycle loading, the slowly progressing damage evolution may not always occur, instead abrupt failure similar to monotonic loading can occur even after passing several load cycles. The size of the fracture process zone (FPZ) was measured using several AE-based and DIC-based methods. The comparison of the approaches indicated that the AE energy-based method is the most suitable to quantify the FPZ size during fatigue damage progress. From AE-based FPZ analysis of the experimental results, it was concluded that for low-cycle loadings, the lack of a well-developed FPZ can be a cause of the sudden brittle failure.

Behaviour of recycled aggregate concrete-filled stainless steel tubular columns subjected to lateral monotonic and cyclic loading

This paper presents a series of experimental research on recycled aggregate concrete-filled stainless steel tubular (RAC-FSST) columns subjected to lateral monotonic and cyclic loading. The influence of axial load level, shear span ratio, and replacement ratio of recycled coarse aggregate on the RAC-FSST members under compression-bending loads is studied. The test results indicate that the RAC-FSST columns exhibit favorable ductility and energy dissipation capacity. The P-Δ skeleton curves of the columns subjected to lateral cyclic loading are similar to those of columns under monotonic loading. It indicates that, compared with the plastic damage of the concrete, the cyclic hardening characteristics of the stainless steel have more significant influence on the bearing capacity. Considering the characteristics of material loading and unloading criteria, a FE model is established to analyze the seismic performance of RAC-FSST, with the internal force development and stress distribution discussed. Based on the parametric analysis, the modification method of bearing capacity and the hysteretic models of RAC-FSST members are proposed.

Study on wear debris characteristics of different polyethylene under reciprocating sliding and compound motion modes

The UHMWPE wear debris has become an important reason affecting the service life and clinical reliability of the prosthesis. In order to further reveal the wear debris characteristics, three kinds of UHMWPE materials including non-crosslinked UHMWPE (UPE), Crosslinked UHMWPE (XLPE) and E-vitamin doped UHMWPE (EXPE) were taken as research objects, and the quantity, size, morphology and distribution characteristics of wear debris under reciprocating sliding and compound motion modes were systematically studied. Among them, the ball-on-disk samples were adopted under reciprocating sliding, and the real ball-on-socket contact mode of artificial cervical disc prosthesis was adopted under compound motion. The tribological experiments were performed with the frequency of 2Hz under 50,000 cycles with newborn bovine serum solution. The results showed that the dominant wear mechanism was abrasive wear accompanied by fatigue cracks under reciprocating sliding mode, while adhesive wear accompanied by a few abrasive wear under compound motion mode. Compared with the quantity of wear debris under reciprocating sliding mode, the number of UHMWPE debris under composite motion mode was reduced by 28.8%, 31.4% and 37.1% for UPE, XLPE and EXPE debris, respectively. The debris results of the three different polymers were consistent in the quantity, size range, morphology and distribution, but different in the size distribution characteristics. The largest proportion of EXPE debris size occurred in the range of less than 1 μm, while the largest proportion of UPE and XLPE debris size ranges from 1 to 5 μm under reciprocating sliding mode. When the debris size was in the range of 1–5 μm under compound motion mode, it accounted for the largest proportion with a value of 55.7%, 66.7% and 74.0% for UPE, XLPE and EXPE debris, respectively. The UHMWPE debris morphology included six main types: spherical, flakes, rods, fibrillar, granular, and other types. Granular and “other types” debris were the dominant types and the sum proportion of these two types of debris for the three kinds of UHMWPE materials was all as high as 80%. Hence, the material type, pair shape, load and movement profiles may have more or less influence on the quantity, size, morphology and distribution characteristics of UHMWPE debris.

Diffusion-Driven Frictional Aging in Silicon Carbide

Friction is the force resisting relative motion of objects. The force depends on material properties, loading conditions and external factors such as temperature and humidity, but also contact aging has been identified as a primary factor. Several aging mechanisms have been proposed, including increased “contact quantity” due to plastic or elastic creep and enhanced “contact quality” due to formation of strong interfacial bonds. However, comparatively less attention has been given to other mechanisms that enhance the “contact quantity”. In this study, we explore the influence of crystal faceting on the augmentation of “contact quantity” in cubic silicon carbide, driven by the minimization of surface free energy. Our observations reveal that the temporal evolution of the frictional aging effect follows a logarithmic pattern, akin to several other aging mechanisms. However, this particular mechanism is driven by internal capillary forces instead of the normal force typically associated with friction. Due to this fundamental distinction, existing frictional aging models fail to comprehensively explain the observed behavior. In light of these findings, we derive a model for the evolution of contact area caused by diffusion-driven frictional aging, drawing upon principles from statistical mechanics. Upon application of a normal force, the friction force is increased due to plastic creep. This investigation presents an alternative explanation for the logarithmic aging behavior observed and offers the potential to contribute to the development of more accurate friction models.Graphical

3D hierarchical self-supporting Bi2Se3-based anode for high-performance lithium/sodium-ion batteries

Bi2Se3 is a promising material for anodes in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) due to its abundance, easy preparation, and high capacity. However, its practical application is hindered by low conductivity and significant volume variation during cycling, leading to poor rate capability and cycling stability. Herein, a novel composite consisting of Bi2Se3 nanoplates deposited on carbon cloth (CC) and encapsulated by reduced graphene oxide (rGO) has been designed and synthesized. The composite structure combines the advantages of the Bi2Se3 nanoplates, CC substrate, and rGO encapsulation, leading to enhanced electrochemical properties. The physical vapor deposition of Bi2Se3 nanoplates onto CC ensures a high loading of active material, while the rGO encapsulation provides a conductive and stable framework for the composite. This synergistic design allows for improved electron and ion transport, as well as efficient accommodation of the volume changes during cycling. In LIBs, the composite demonstrates a high reversible capacity of 467.5 mAh/g at 0.1 A/g after 120 cycles. Moreover, it displays an outstanding rate capability, delivering a capacity of 398.6 mAh/g at 5.0 A/g. Similarly, in SIBs, the composite maintains a reversible capacity of 375.3 mAh/g at 0.1 A/g over 100 cycles and exhibits a high-rate capacity of 286.3 mAh/g at 5.0 A/g. This work represents a significant step forward in addressing the challenges associated with Bi2Se3 as an anode material, paving the way for the development of high-performance LIBs and SIBs.

Electrochemical activation strategy enabled ammonium vanadate cathodes for all-climate zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) have attracted significant attention for grid-scale energy applications due to their low cost, intrinsic safety, and environmental friendliness. However, the energy density of current ZIBs is impeded by unsatisfactory performance of cathodes, due to their limited areal capacity and low active material loading, especially at extreme environments. Herein, an electrochemical activation strategy is put forward to build high energy density ZIBs by designing a flexible cathode composed of NH4+ pillared ammonium vanadate nanosheets on carbon cloth (NVMCE@CC). The electrochemical activation process with high anodic potential (> 1.5 V vs. Zn2+/Zn) guarantees the effective conversion of low-valent to high-valent vanadium and promotes the utilization of large amounts of vanadium elements in the NVMCE@CC composite. Meanwhile, the pillared NH4+ ions expand the interlayer spacing and enhance the structural integrity through the hydrogen bonding between NH4+ and V-O framework. Consequently, the activated NVMCE@CC cathode with a high mass-loading of ∼5.2 mg cm−2 delivers large areal capacity (∼1.74 mAh cm−2 at 1 mA cm−2) and superior cycling stability (capacity retention of 72.1% after 1500 cycles). Importantly, the flexible cathode shows admirable capacities of 0.52 mAh cm−2 at 60 °C and 0.55 mAh cm−2 at − 10 °C, respectively. Moreover, the NVMCE@CC//Zn@CC quasi-solid-state battery demonstrates excellent safety performance and performs well in extreme situations, including bending, cutting, hammering, and washing. This work provides enlightenment for the development of large-areal-capacity vanadium-based cathode materials for practical ZIBs.

Mathematical formulation and a novel two-stage algorithm for double-row layout problem with fixed loading and unloading points

Loading and unloading operations are frequent and important in the production workshop. Thus, this paper proposes a novel double-row layout problem, which involves the location planning of material loading and unloading points of the facility in the layout; It needs to solve the sequence and precise coordinates of facilities with safety clearance to ensure the safety of the layout. Subsequently, a mixed-integer programming model and an improved discrete differential evolution algorithm with linear programming are developed to minimize material handling costs. The algorithm includes four efficient operations in optimization: the annealing mechanism, random strategy, variable neighborhood search strategy, and double-threshold termination mode. Thereafter, compared with the computational results of benchmark cases, the validity of the model and the efficiency of the algorithm are verified. In the basic problem, the calculation results of the algorithm are compared with many algorithms in the literature, and the algorithm still performs well. Finally, the algorithm is applied to solve the reducer workshop and provides a better layout scheme.