Two-dimensional Aggregates Research Articles

Study on hydrophobic floc structure of coal particles based on fractal simulation

Utilizing the Matlab platform, two-dimensional diffusion-limited aggregation and three-dimensional diffusion-limited cluster aggregation models were established to simulate the hydrophobic flocculation of coal particles. The formation process of flocs aggregated by monomer particles and small groups was simulated from both plane and space perspectives. The gyration radius fractal dimension increased from 1.401 to 1.539 in the DLA model and from 1.623 to 1.729 in the DLCA model, indicating that the floc morphology gradually stabilized and the structure became increasingly regular during the hydrophobic flocculation process. The porosity of DLA increased from 0.762 to 0.851, indicating that the dendritic structure of flocs formed a spatial shielding effect on the planar structure, which prevented the particles from entering the flocs. In contrast, the porosity of DLCA first increased from 0.506 to 0.611 and then decreased, stabilizing at approximately 0.53, indicating that small groups filled the internal voids of flocs in the spatial structure, leading to a gradual increase in floc density. The surface fractal dimension and density of flocs were calculated using the surface fractal and hydrostatic sedimentation-terminal velocity theories, respectively, confirming the conclusions drawn from the simulation analysis.

Crystal structure of bis-(μ2-5-nona-noylquinolin-8-olato)bis-[aqua-dichlorido-indium(III)

Crystallization of 5-nona-noyl-8-hy-droxy-quinoline in the presence of InCl3 in aceto-nitrile yields a dinuclear InIII complex crystallizing in the space group P. In this complex, [In2(C18H22NO2)2Cl4(H2O)2], each indium ion is sixfold coordinated by two chloride ions, one water mol-ecule and two 8-quinolino-late ions. The crystal of the title complex is composed of two-dimensional supra-molecular aggregates, resulting from the linkage of the Owater-H⋯O=C and Owater-H⋯Cl hydrogen bonds as well as bifurcated Carene-H⋯Cl contacts.

Determining the Size of Representative Volume Elements for a Two-Dimensional Random Aggregate Numerical Model of Asphalt Mortar without Damage.

The size of the representative volume element (RVE) for the two-dimensional (2D) random aggregate numerical model of asphalt mortar in a non-destructive state, which directly affects the time required to simulate the linear viscoelastic behavior from asphalt mastic to asphalt mortar. However, in the existing literature, limited research has been conducted on the size determination of the numerical model RVE for asphalt mortar. To provide a recommended size for the typical 2D random aggregate numerical model RVE of asphalt mortar in a nondestructive state, this paper first applies the virtual specimen manufacturing method of asphalt concrete 2D random aggregate to asphalt mortar. Then, it generates numerical model RVEs of asphalt mortar with different maximum particle sizes, after which geometric and numerical analyses are conducted on these models. Finally, based on the geometric and numerical analysis results, the recommended minimum sizes of RVE for the 2D asphalt mortar numerical model are provided.

Graph topological transformations in space-filling cell aggregates.

Cell rearrangements are fundamental mechanisms driving large-scale deformations of living tissues. In three-dimensional (3D) space-filling cell aggregates, cells rearrange through local topological transitions of the network of cell-cell interfaces, which is most conveniently described by the vertex model. Since these transitions are not yet mathematically properly formulated, the 3D vertex model is generally difficult to implement. The few existing implementations rely on highly customized and complex software-engineering solutions, which cannot be transparently delineated and are thus mostly non-reproducible. To solve this outstanding problem, we propose a reformulation of the vertex model. Our approach, called Graph Vertex Model (GVM), is based on storing the topology of the cell network into a knowledge graph with a particular data structure that allows performing cell-rearrangement events by simple graph transformations. Importantly, when these same transformations are applied to a two-dimensional (2D) polygonal cell aggregate, they reduce to a well-known T1 transition, thereby generalizing cell-rearrangements in 2D and 3D space-filling packings. This result suggests that the GVM's graph data structure may be the most natural representation of cell aggregates and tissues. We also develop a Python package that implements GVM, relying on a graph-database-management framework Neo4j. We use this package to characterize an order-disorder transition in 3D cell aggregates, driven by active noise and we find aggregates undergoing efficient ordering close to the transition point. In all, our work showcases knowledge graphs as particularly suitable data models for structured storage, analysis, and manipulation of tissue data.

Asymptotic analysis of particle cluster formation in the presence of anchoring sites

The aggregation or clustering of proteins and other macromolecules plays an important role in the formation of large-scale molecular assemblies within cell membranes. Examples of such assemblies include lipid rafts, and postsynaptic domains (PSDs) at excitatory and inhibitory synapses in neurons. PSDs are rich in scaffolding proteins that can transiently trap transmembrane neurotransmitter receptors, thus localizing them at specific spatial positions. Hence, PSDs play a key role in determining the strength of synaptic connections and their regulation during learning and memory. Recently, a two-dimensional (2D) diffusion-mediated aggregation model of PSD formation has been developed in which the spatial locations of the clusters are determined by a set of fixed anchoring sites. The system is kept out of equilibrium by the recycling of particles between the cell membrane and interior. This results in a stationary distribution consisting of multiple clusters, whose average size can be determined using an effective mean-field description of the particle concentration around each anchored cluster. In this paper, we derive corrections to the mean-field approximation by applying the theory of diffusion in singularly perturbed domains. The latter is a powerful analytical method for solving two-dimensional (2D) and three-dimensional (3D) diffusion problems in domains where small holes or perforations have been removed from the interior. Applications range from modeling intracellular diffusion, where interior holes could represent subcellular structures such as organelles or biological condensates, to tracking the spread of chemical pollutants or heat from localized sources. In this paper, we take the bounded domain to be the cell membrane and the holes to represent anchored clusters. The analysis proceeds by partitioning the membrane into a set of inner regions around each cluster, and an outer region where mean-field interactions occur. Asymptotically matching the inner and outer stationary solutions generates an asymptotic expansion of the particle concentration, which includes higher-order corrections to mean-field theory that depend on the positions of the clusters and the boundary of the domain. Motivated by a recent study of light-activated protein oligomerization in cells, we also develop the analogous theory for cluster formation in a three-dimensional (3D) domain. The details of the asymptotic analysis differ from the 2D case due to the contrasting singularity structure of 2D and 3D Green’s functions.Graphical abstract2D model of diffusion-based protein cluster formation in the presence of anchoring cites and particle recycling. a A set of N anchoring sites at positions xj\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ extbf{x}}_j$$\\end{document}, j=1,…,N\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$j=1,\\ldots ,N$$\\end{document}, in a bounded domain Ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Omega $$\\end{document}. b Diffusing particles accumulate at the anchoring sites resulting in the formation of particle aggregates or clusters Uj\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\\mathcal {U}}}_j$$\\end{document}. c The clusters are dynamically maintained by a combination of lateral diffusion outside the clusters and particle recycling

Optical assembly of multi-particle arrays by opto-hydrodynamic binding of microparticles close to a one-dimensional chain of magnetic microparticles.

Two-dimensional materials possess a large number of interesting and important properties. Various methods have been developed to assemble two-dimensional aggregates. Assembly of colloidal particles can be achieved with laser-heating-induced thermal convective flow. In this paper, an opto-hydrodynamic binding method is proposed to assemble colloidal particles dispersed in a solution into multilayer structures. First, we use polystyrene (PS) microspheres to study the feasibility and characteristics of the assembly method. PS microspheres and monodispersed magnetic silica microspheres (SLEs) are dispersed in a solution to form a binary mixture system. Under the action of an external uniform magnetic field, SLEs in the solution form chains. An SLE chain is heated by a laser beam. Due to the photothermal effect, the SLE chain is heated to produce a thermal gradient, resulting in thermal convection. The thermal convection drives the PS beads to move toward the heated SLE chain and finally stably assemble into multilayer aggregates on both sides of the SLE chain. The laser power affects the speed and result of the assembly. When the laser power is constant, the degree of constraint of the PS microbeads in different layers is also different. At the same time, this method can also assemble the biological cells, and the spacing of different layers of cells can be changed by changing the electrolyte concentration of the solution. Our work provides an approach to assembling colloidal particles and cells, which has a potential application in the analysis of the collective dynamics of microparticles and microbes.

Synthesis and crystal structures of two solvates of 1-{[2,6-bis-(hy-droxy-meth-yl)-4-methyl-phen-oxy]meth-yl}-3,5-bis-{[(4,6-di-methyl-pyridin-2-yl)amino]meth-yl}-2,4,6-tri-ethyl-benzene.

In the crystal structures of the formamide monosolvate (1a) and the n-propanol/H2O solvate/hydrate (1b) of the title compound, C38H50N4O3 (1), the tripodal host mol-ecule adopts a conformation in which the substituents attached to the central benzene ring are arranged in an alternating order above and below the ring plane. As a result of the different nature of the involved guest species, the crystal components in 1a create a three-dimensional supra-molecular architecture, while the crystal structure of 1b consists of two-dimensional supra-molecular aggregates extending parallel to the crystallographic ab plane.

Supramolecular Polymer Polymorphism: Spontaneous Helix-Helicoid Transition through Dislocation of Hydrogen-Bonded π-Rosettes.

Polymorphism, a phenomenon whereby disparate self-assembled products can be formed from identical molecules, has incited interest in the field of supramolecular polymers. Conventionally, the monomers that constitute supramolecular polymers are engineered to facilitate one-dimensional aggregation and, consequently, their polymorphism surfaces primarily when the states of assembly differ significantly. This engenders polymorphs of divergent dimensionalities such as one- and two-dimensional aggregates. Notwithstanding, realizing supramolecular polymer polymorphism, wherein polymorphs maintain one-dimensional aggregation, persists as a daunting challenge. In this work, we expound upon the manifestation of two supramolecular polymer polymorphs formed from a large discotic supramolecular monomer (rosette), which consists of six hydrogen-bonded molecules with an extended π-conjugated core. These polymorphs are generated in mixtures of chloroform and methylcyclohexane, attributable to distinctly different disc stacking arrangements. The face-to-face (minimal displacement) and offset (large displacement) stacking arrangements can be predicated on their distinctive photophysical properties. The face-to-face stacking results in a twisted helix structure. Conversely, the offset stacking induces inherent curvature in the supramolecular fiber, thereby culminating in a hollow helical coil (helicoid). While both polymorphs exhibit bistability in nonpolar solvent compositions, the face-to-face stacking attains stability purely in a kinetic sense within a polar solvent composition and undergoes conversion into offset stacking through a dislocation of stacked rosettes. This occurs without the dissociation and nucleation of monomers, leading to unprecedented helicoidal folding of supramolecular polymers. Our findings augment our understanding of supramolecular polymer polymorphism, but they also highlight a distinctive method for achieving helicoidal folding in supramolecular polymers.

Anisotropic Purcell Effect and Quantum Interference in Fractal Aggregates of Nanoparticles

We study theoretically the emergence of an anisotropic Purcell factor in random two-dimensional fractal aggregates of nanoparticles. These nanoparticles can either be metallic nanoparticles made of silver, which exhibit surface plasmon resonances, or high-index dielectric nanoparticles like silicon, which possess optical Mie resonances. To calculate the spontaneous emission rates of a quantum emitter, we utilize the electromagnetic Green’s tensor within the framework of the coupled-dipole method. Our findings reveal that the Purcell factor exhibits spatial variations, with certain regions, referred to as hot spots, displaying high values for dipoles oriented within the plane of the fractal aggregate, while dipoles oriented vertically to the aggregate have values close to unity. This anisotropy in the Purcell factor leads to significant quantum interference effects in the spontaneous emission paths of multi-level quantum emitters. As a consequence of this quantum interference, we demonstrate the occurrence of population trapping in a V-type quantum emitter embedded within a fractal aggregate of nanoparticles which cannot otherwise take place if the emitter is placed in vacuum.

CuTPP films grown on ceramic and ITO-coated glasses

α, β, γ, δ—Copper(II) tetraphenylporphyrinate (CuTPP) has been investigated as an active material in composites for optoelectronic devices, such as organic light-emitting diodes (OLEDs). This study focused on the spectroscopic, structural, and morphological analysis of CuTPP thin films obtained using layer-by-layer deposition. The infrared spectra of the films, deposited both on ceramic glass and indium tin oxide-coated glass, revealed that the substrate interacts with CuTPP, inducing the formation of aliphatic CH2 or CH3 and a general rearrangement of the bands related to the bending of phenyl groups. UV–vis spectroscopy indicated the presence of two bands at 350 and 472 nm in the films, instead of the intense band in the region between 380 and 500 nm corresponding to the Soret band. The structure of the complex was elucidated by single-crystal X-ray diffraction. X-ray powder diffraction analysis showed that films exhibited two peaks associated with the 101 and 103 planes, which noticeably increased after heating at 200 °C. Scanning electron microscopy images confirmed that the annealing favored the growth of two-dimensional square-shaped aggregates on the surface of the substrate.

Image-based methods for automatic identification of elongated and flat aggregate particles

The content of elongated and flat aggregates is a critical detection index in road engineering. In this study, using image sequences of falling aggregates, two multi-view morphological methods were proposed for aggregate shape classification. The multi-view features of the aggregates were constructed by combining multiple single-view features from different views. Furthermore, a joint-view normalization method was proposed to improve the three-dimensional shape characterization capability of the multi-view features. Based on the multi-view features, a support vector machine was adopted to achieve aggregate shape classification. In addition, multiple two-dimensional aggregate morphologies from different views were directionally guided and fused to construct a multi-view image, which could reflect the three-dimensional shape of the aggregates. The multi-view images were then fed into ResNet18 for aggregate-shape classification. Notably, compared with single-view morphological methods based on the aggregate morphology in the vertical and random views, the two multi-view morphological methods developed herein significantly improved the classification accuracy. Moreover, it was found experimentally that increasing the height of the field of view improved the classification accuracy of the multi-view morphological methods. The proposed multi-view morphological methods demonstrate significant potential for application in the automatic identification of elongated and flat aggregates in road construction.

An optimal aggregation method for interval grey numbers using on Steiner-Weber point with application

Aiming at the problem of low accuracy of two-dimensional preference information aggregation, this paper takes two-dimensional interval grey numbers as an example to define its preference information mapping rules. This rule maps preference information to preference points on a two-dimensional plane. Based on the theory of plane Steiner-Weber point, we construct a two-dimensional optimal model, and prove the optimality of the model theoretically. Then, adopt plant growth simulation algorithm (PGSA) to solve the proposed model. The obtained optimal aggregation point that can represent the comprehensive opinions. Finally, by analyzing the selection problem of Fangcang shelter hospital and comparing it with the particle swarm optimization (PSO) method, we conclude that the sum of weighted Euclidean distance obtained by our method is minimal. The aggregation precision of our method is higher than that of other aggregation method to a certain extent.

Supramolecular aggregation featuring Hg⋯S secondary-bonding interactions in crystals of mercury(ii) species augmented by computational chemistry calculations

A CSD survey reveals the presence of Hg⋯S interactions within zero-, one- and two-dimensional aggregation patterns in non-organomercury crystals. Theory confirms the stabilising nature of σ-/π-holes or positive belts formed at the mercury atom.

Optical response and multi-exciton effects in 2D PTCDA aggregates with local excitation.

3,4,9,10-Perylenetetracarboxylic-dianhydride (PTCDA) aggregates have unique optical properties and are model materials for studying exciton energy transfer (EET) in planar stacked molecular aggregates. In the framework of density matrix theory, a hierarchy of molecular transition operator expectation values could be constructed to derive the equations of motion of multi-exciton states. Realistic parameters for PTCDA molecules are used to study EET and the optical response of two-dimensional aggregates upon local excitation. Our simulations show that information about the dark state can be obtained with local field excitation and the inter-chain coupling results in a red-shift of the lowest excitonic energy level. Configuration effects, inter-chain detuning and multi-exciton states are discussed. The calculated lowest excitonic energy level of a 2D PTCDA aggregate is qualitatively consistent with the lowest experimental absorption peak of a PTCDA film. The obtained results are valuable for the study of aggregates in optical nanocavities and for the design of photoelectric devices.

The Dynamic Freight Routing Problem for Less-Than-Truckload Carriers

Less-than-truckload (LTL) carriers transport freight shipments from origins to destinations by consolidating freight using a network of terminals. As daily freight quantities are uncertain, carriers dynamically decide freight routes on the day of operations. We introduce the dynamic freight routing problem (DFRP) and model this problem as a Markov decision process (MDP). To overcome the curses of dimensionality of the MDP model, we introduce an approximate dynamic programming (ADP) solution approach that uses a lookup table to store value function approximations and present and compares a number of aggregation approaches that use features of the postdecision states (PDSs) to aggregate the PDS space and reduce the number of entries in the lookup table. Furthermore, because the decision subproblems are integer programs (IPs), we present a framework for integrating lookup tables into the decision subproblem IPs. This framework consists of (1) a modeling approach for the integration of lookup table value function approximations into subproblem IPs to form extended subproblem IPs; (2) a solution approach, PDS-IP-bounding, which decomposes the extended subproblem IPs into many smaller IPs and uses dynamic bounds to reduce the number of small IPs that have to be solved; and (3) an adaptation of the ϵ-greedy exploration-exploitation algorithm for the IP setting. Our computational experiments show that despite the DFRP having high-dimensional PDS vectors, a two-dimensional aggregation of the space can produce policies that outperform standard myopic policies. Moreover, they demonstrate that the PDS-IP-bounding algorithm provides computational advantages over solving the extended subproblem IPs using a commercial solver. Funding: A. Baubaid acknowledges financial support from the King Fahd University of Petroleum & Minerals. Supplemental Material: The online appendices are available at https://doi.org/10.1287/trsc.2022.1190 .

The Combined Application Technology of the Bank's TwoDimensional Aggregate Payment Code and the Vegetable Field Traceability System

With the rapid development of social economy, people's living standards and quality of life are getting better and better, and food safety is getting more and more attention. Aiming at the problem of vegetable traceability, this paper analyzes the bank's QR code scan code aggregation payment model. Secondly, it designs a green food traceability system and elaborates the realization of the main functions of the system. Practice has proved that the traceability system of green food can allow consumers to consume with confidence, and at the same time, it is convenient for the competent government departments to trace the source in time and control the quality.

Calculation and Analysis of Temperature Damage of Shimantan Concrete Gravity Dam Based on Macro-Meso Model.

Considering that ANSYS software will automatically quit or the computer will freeze when generating random aggregate models of concrete by using some existing methods that are based on the ANSYS parametric design language (APDL), a new method of random aggregate placement using the ESEL command in APDL and the rotation of the local coordinate system is proposed in this paper. According to this method, a multiscale macroscopic and mesoscopic finite element model of the No. 9 non-overflow dam section of Shimantan dam is constructed. In addition, considering that most of the damage models adopted by the existing mesoscale simulation of concrete damage and fracture cannot take into account the interaction between aggregates, interfacial transition zone (ITZ), and mortar, an improved anisotropic temperature damage model is proposed in this paper. The aggregate placement simulation results show that the method presented in this paper can quickly generate two-dimensional (2D) random concrete aggregates, and the generation of three-dimensional (3D) aggregates can also be completed in a very short time, which can greatly improve the aggregate generation efficiency. Moreover, the aggregate shape generated by this method is very close to the real concrete aggregate shape. The crack propagation simulation results show that the sudden rise and fall of temperature can cause damage in the mortar and ITZ of concrete inside the dam body, which is the main reason for the generation of macroscopic through-cracks in the No. 9 non-overflow dam section of Shimantan dam during the operation period. Finally, it can be learned from the results that the method presented in this paper is reasonable and feasible, and can be extended to the crack propagation simulation of some other concrete gravity and arch dams.

Galaxy Zoo: Clump Scout – Design and first application of a two-dimensional aggregation tool for citizen science

ABSTRACT Galaxy Zoo: Clump Scout is a web-based citizen science project designed to identify and spatially locate giant star forming clumps in galaxies that were imaged by the Sloan Digital Sky Survey Legacy Survey. We present a statistically driven software framework that is designed to aggregate two-dimensional annotations of clump locations provided by multiple independent Galaxy Zoo: Clump Scout volunteers and generate a consensus label that identifies the locations of probable clumps within each galaxy. The statistical model our framework is based on allows us to assign false-positive probabilities to each of the clumps we identify, to estimate the skill levels of each of the volunteers who contribute to Galaxy Zoo: Clump Scout and also to quantitatively assess the reliability of the consensus labels that are derived for each subject. We apply our framework to a data set containing 3561 454 two-dimensional points, which constitute 1739 259 annotations of 85 286 distinct subjects provided by 20 999 volunteers. Using this data set, we identify 128 100 potential clumps distributed among 44 126 galaxies. This data set can be used to study the prevalence and demographics of giant star forming clumps in low-redshift galaxies. The code for our aggregation software framework is publicly available at: https://github.com/ou-astrophysics/BoxAggregator

Mesoscale Finite Element Modeling of Mortar under Sulfate Attack.

In this paper, a 2D mesoscale finite element (FE) numerical model of mortar, considering the influence of the ITZ, was proposed to evaluate the corrosion of mortar in sodium sulfate. On the mesoscale, the corroded mortar was regarded as a three-phase composite material composed of sand, cement paste, and an interface transition zone (ITZ). Firstly, the volume fractions and mechanical parameters (elastic modulus, Poisson’s ratio, and strength) of the mesoscale phases were obtained. Then, the cement paste and the ITZ were combined to form an equivalent matrix by homogenization methods, and the calibrated constitutive relations of the equivalent matrix were established. Subsequently, a two-dimensional (2D) random circular aggregate (RCA) model and a 2D random polygonal aggregate (RPA) model of corroded mortar were established using the random aggregate model. The failure process of corroded mortar specimens under uniaxial compression was simulated by the mesoscale FE numerical model. Comparing the simulation results with the measured stress–strain curves of the uniaxial compression test, it was found that the simulation results of the 2D RP model were closer to the experimental results than those of the 2D RC model. Meanwhile, the numerical simulation results were in good agreement with the experimental results, and the error values of peak stress between the simulation results and the measured results were within 7%, which showed that the 2D mesoscale FE model could accurately predict the results of a uniaxial compression test of a mortar specimen under sulfate attack.

Crystal structures of methyl 3,5-di-methyl-benzoate, 3,5-bis-(bromo-meth-yl)phenyl acetate and 5-hy-droxy-benzene-1,3-dicarbaldehyde.

The crystal structures of the title compounds, methyl 3,5-di-methyl-benzoate (C10H12O2; 1), 3,5-bis-(bromo-meth-yl)phenyl acetate (C10H10Br2O2; 2) and 5-hy-droxy-benzene-1,3-dicarbaldehyde (C8H6O3; 3) were determined by single-crystal X-ray analysis. The crystals of 1 are composed of strands of C-H⋯O=C bonded mol-ecules, which are further arranged into layers. As a result of the presence of two bromo-methyl substituents in compound 2, mol-ecular dimers formed by crystallographically non-equivalent mol-ecules are connected to structurally different two-dimensional aggregates in which the bromine atoms participate in Br⋯Br bonds of type I and type II. In the case of compound 3, which possesses three donor/acceptor substituents, the mol-ecular association in the crystal creates a close three-dimensional network comprising Car-yl-H⋯Ohy-droxy, Cform-yl-H⋯Oform-yl and O-H⋯Oform-yl bonds.