A spherocylinder, a convex 3D object consisting of a cylinder with two hemispherical ends, can possess a wide range of aspect ratios and is one of the most studied non-spherical particle shapes. ...Previous investigations on disordered spherocylinder packings yielded inconsistent packing characteristics, especially the packing density φ, indicating that density alone is not sufficient to uniquely characterize a packing. In this paper, we delineate in the density–order–metric diagram (i.e. order map) the border curve that separates geometrically feasible and infeasible packings of congruent spherocylinders via the geometric-structure approach, i.e., by generating and analyzing a large number of packing configurations with a diversity of densities and degrees of order generated via a relaxation algorithm. We find that the border curve possesses a sharp transition as the packing density increases, i.e., the initial increase of φ is not associated with any notable increase of the degree of order, while beyond a threshold φ value, the increase of density is strongly positively correlated with the increase of order. This allows us to propose the concept of maximally dense random packing (MDRP) state for spherocylinders, which corresponds to the transition point in the boarder curve and characterizes the on-set of nontrivial spatial correlations among the particles. It can also be considered as the maximally dense packing arrangement of spherocylinders without nontrivial spatial correlations. The degree of order of a spherocylinder packing is quantified via the nematic order parameter (S) and the local order metric (SLocal), which respectively characterize the level of global orientational order and local order in particle clusters. The latter metric SLocal, which measures the average order in the neighborhoods of particles with the second Legendre polynomial, is a new order metric for spherocylinder systems. We find that the packing density of the MDRPs initially increases with the increase of the aspect ratio w from 0, and reaches the maximal value of 0.725 when w=0.5, then drops with further increase of w. The MDRP at w=0.5 is verified to be jammed via a Monte Carlo jamming-testing algorithm and thus, should also represent the maximally random jammed (MRJ) packing state as well.
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•The local order in clusters is identified as a main order form in geometric spherocylinder packing.•A new local order metric SLocal is proposed to quantify the local order in clusters.•The concept of maximally dense random packing (MDRP) state in spherocylinder packings is proposed.•In the MDRP state, the packing properties in terms of the aspect ratio are presented.
•Eight-carbon PFAS were dominant in the Bohai Sea.•The highest ∑PFAS were observed in the Laizhou Bay for seawater and in the Liaodong Bay for sea sediments, respectively.•Six primary sources were ...revealed by using PMF 5.0 software.•The environmental risk of PFAS was not high in the Bohai Sea.
In this study, the occurrence, distribution, sources, and risk of 29 legacy and emerging per- and polyfluoroalkyl substances (PFAS) in four kinds of environmental matrices in the Bohai Sea were investigated. The ∑PFAS concentrations were in the range of 0.40 ~ 61.4 ng/g dry weight (dw) in inflow river sediments, 0.48 ~ 61.4 ng/g dw in soil near river inflow, 0.37 ~ 4.18 ng/g dw in sea sediments, and 13.3 ~ 718 ng/L in seawater. PFAS with eight carbons accounted for > 62.2% by mass, in all samples. Perfluorooctanoic acid (PFOA) was the dominant PFAS both by mass and occurrence. Seawater from Laizhou Bay (south of the Bohai Sea) and sediments of Liaodong Bay (northeast of the Bohai Sea) had the highest levels of ∑PFAS. The sediment–water partition coefficient and organic carbon content normalized partition coefficient (log Kd and log Koc) were calculated using measured PFAS concentrations to determine their distribution in seawater and sea sediments. The values of log Kd and log Koc values increased with the increasing CF2 units for perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs). Six primary sources were identified in this region, including aqueous film-forming foams (AFFF), metal plating, food packages, fluorine chemical industry, fluoropolymer manufacture, and domestic pollution. The risk quotient (RQ) values of PFAS were all < 1, indicating that organisms of the Bohai Sea were at low risk of PFAS exposure.
Shear band behaviour plays a critical role in toughening and failure of bulk metallic glasses (BMGs). However, due to instability in time and inhomogeneity in space, spatial–temporal evolutions of ...shear bands are difficult to be studied in the past decades. Using digital image correlation (DIC) and infrared thermal imaging (ITI) technologies, uniaxial quasi-static compressions for Zr41.2Ti13.8Ni10Cu12.5Be22.5 BMG are carried out. The spatial–temporal evolutions of shear bands, as well as the relationship between shear band and failure in BMGs, are in-situ investigated. A theoretical evaluation of temperature is performed based on the heat conduction theory, in line with the experimental data. Moreover, a free volume theory-based amorphous viscoplasticity model is implemented by finite element method (FEM) to understand the shear band behaviour further. The nucleation, propagation, intersection of shear bands are investigated in detail, and the simulation results are in agreement with the experiments in some respects. Besides, it is found that the primary shear band tends to be activated more easily along a so-called dominant path generated after shear-band competitions. This paper provides insights for the prediction of the primary shear band, prevention of failure, and toughening method in BMGs.
Tin‐based perovskite solar cells (TPSCs) are attracting intense research interest due to their excellent optoelectric properties and eco‐friendly features. To further improve the device performance, ...developing new fullerene derivatives as electron transporter layers (ETLs) is highly demanded. Four well‐defined regioisomers (trans‐2, trans‐3, trans‐4, and e) of diethylmalonate‐C60 bisadduct (DCBA) are isolated and well characterized. The well‐defined molecular structure enables us to investigate the real structure‐dependent effects on photovoltaic performance. It is found that the chemical structures of the regioisomers not only affect their energy levels, but also lead to significant differences in their molecular packings and interfacial contacts. As a result, the devices with trans‐2, trans‐3, trans‐4, and e as ETLs yield efficiencies of 11.69%, 14.58%, 12.59%, and 10.55%, respectively, which are higher than that of the as‐prepared DCBA‐based (10.28%) device. Notably, the trans‐3‐based device also demonstrates a certified efficiency of 14.30%, representing one of the best‐performing TPSCs.
Structure‐dependent effects of the four fullerene bisadduct regioisomers on the device performance of tin‐based perovskite solar cells are systemically investigated. Benefiting from the favorable molecular packing, energy level alignment, and interfacial interaction, the trans‐3‐based devices yield a champion efficiency of 14.58% with a certified efficiency of 14.30%, representing one of the best‐performing tin‐based devices.
Since the COVID-19 pandemic broke out in 2019, neuroticism has been proven a predictor of fear of COVID-19 infection. However, only few studies have been conducted on the factors affecting the ...relationship between neuroticism and this kind of fear. The present study is aimed at analyzing the role intolerance of uncertainty (IU) and sense of control (SOC) play in relation to neuroticism and the fear of COVID-19. We conducted a cross-sectional study in Guangdong and Guangxi provinces, China, and we collected complete datasets from 792 high school students. The main results can be described as follows: (a) individuals with high neuroticism tended to have higher intolerance of uncertainty (IU) and a lower sense of control (SOC); (b) IU and SOC played a mediating role between neuroticism and fear of COVID-19, and a serial mediation effect was found between these factors; (c) after controlling for both IU and SOC, the effect of neuroticism on fear was no longer significant. The results suggested a critical role of IU and sense of control in the causal relationship between neuroticism and fear.
A polyethylenimine (PEI)-scaffolded and functionalized graphene aerogel, PEI-GO-AG, was prepared and utilized as a highly selective adsorbent for the extraction of thorium (Th) (IV) from three ...lanthanides (Ln) (III) elements. The three dimensional (3D)-porous structure of the adsorbent was established by the cross-linking effect of PEI via a one-step hydrothermal strategy and preserved by a freeze-drying treatment to avoid the collapse of the structure. The extractive efficiency of PEI-GO-AG displayed a sensitive dependence on the beginning mass ratio of PEI/graphene oxide (GO) in the hydrothermal step because of its significant influence on the hydrophilicity and the amounts of introduced binding sites of the adsorbent.. Besides, a density function theory (DFT)-based theoretical calculation was performed, confirming the higher stability of Th (IV)-PEI-GO-AG than that of Ln (III)-PEI-GO-AG. Ascribed to these contributions, the as-prepared adsorbent showed high selectivity towards Th (IV) among three Ln (III) elements. The separation factor (SF) values of Th (IV) to lanthanum (La) (III), europium (Eu) (III), and lutetium (Lu) (III) were SFTh/La = 114.41, SFTh/Eu = 52.75, and SFTh/Lu = 107.81, respectively.
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•1Dimensional-porous graphene oxide aerogel was established using polyethylenimine as the cross-linking and functionalizing agent.•The adsorbent possesses high selectivity arising from the dimensional-porous structure, the introduced binding sites, and the high hydrophilicity.•The adsorptive performance of the adsorbent showed a sensitively dependent relationship on the beginning mass ratio of polyethylenimine/graphene oxide.•A density functional theory simulation was performed, proving the adsorption complex of thorium possessed the lowest energy.
The substrates formed by the self-assembly method of metal nanoparticles are widely used in the molecular detection due to their high uniformity and good SERS properties. In this paper, we used the ...sliver nanorods as the building block for the first time to produce close-packed vertical arrays via evaporation-induced method. The results showed that the optimized substrates have good performance with excellent enhancement factor (4.47 × 10
5
) and high reproducibility. By the time, we explore the relationship between the length of silver nanorods and the intensity of 4-mercaptobenzoic acid (4-MBA). The optimal SERS performance depended on longest silver nanorod length. In addition, the optimized vertical silver nanorod substrates exhibit 3 times than the optimized six-layer three-dimensional horizontal ones. Furthermore, the optimized substrate was able to directly detect malachite green (MG) down to 10
−9
M. At the same time, the on-site detection of the thiram in the peel of apple is as low as 0.1 ng cm
−2
. The experimental results clearly show that our substrates have great potential for environmental monitoring, food safety and security application.
As the power grid undergoes transformation and the Internet’s influence grows, the electricity market is evolving towards informatization. The expanding scale of the power grid and the increasing ...complexity of operating conditions have generated a substantial amount of data in the power market. The traditional power marketing model is no longer suitable for the modern power market’s development trend. To tackle this challenge, this study employs random forest and RBF models for processing electricity market data. Additionally, it explores the synergy of graph convolutional network and spectral clustering algorithms to enhance the accuracy and efficiency of data mining, enabling a comprehensive analysis of data features. The experimental results successfully extracted various electricity consumption features. This approach contributes to the informatization efforts of power grid enterprises, enhances power data perception capabilities, and offers reliable support for decision makers.
Herein, we present a new strategy in which highly emissive thermally activated delayed fluorescence (TADF) materials can be obtained from modifying or tuning a non-TADF donor (D)–acceptor (A)-type ...organic molecule via coordination of the metal ionic fragment. Theoretical calculation and photophysical properties reveal that the D–A-type free ligand emits both weak fluorescence and dual room-temperature phosphorescence, whereas the two Ag(I) complexes display efficient blue TADF, exhibiting photoluminescence quantum yields nearly 100% in films with short decay lifetimes (τ ≈ 6 μs). This is attributed to the four optimized parameters induced by Ag(I) coordination: (1) narrow singlet (S1)–triplet (T1) energy gaps (ΔE ST). (2) T1 states have a hybrid local excitation and charge transfer (CT) character, and S1 states have a predominant CT character. Both the parameters facilitate reverse intersystem crossing. (3) Radiative rate constant (k r(S1→S0)) is increased. (4) Molecular rigidity is strengthened. For the first time, this work shows a powerful method to design efficient ligand-centered TADF in Ag(I) complexes based on the conventional D–A-type molecule, which significantly enriches the chemical space for the development of TADF materials.
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