Cluster Aggregation Research Articles

Cluster aggregation of water-based deep eutectic solvents in water and evaluation of their cytotoxicity

Deep Eutectic Solvents (DESs) are emerging in the recent literature as promising environmentally friendly liquids in different topics, finding fruitful applications as substitutes to common volatile organic solvents.In this work a study of cluster formation of water-based DESs in water dilutions is presented. The three analysed mixtures are: glycolic acid/water (GA/H2O); betaine/water (TMG/H2O), choline chloride/water (ChCl/H2O). Ionic conductivity, viscosity, ultrasound spectroscopy and NMR techniques showed the presence of aggregates of aquoDESs in water dilutions. These aggregates are present in the solutions until values about 50 % w/w of added water, showing the presence of water-in-water structured systems. Moreover, taking into account the convenient disposal as water dilution of a DES, the cytotoxicity of these dilutions was evaluated on Caco2 model cells, showing the effect to be related only to the non-water components of these liquids. The water dilutions of water-based DESs have a great relevance for their applications, because their physical properties can be modulated as needed preserving their DESs’ identities.

Amyloid-like Aggregation Propensities of Metabolites- Homogentisic Acid, N-Acetyl Aspartic Acid and Isovaleric Acid.

The transformation of metabolites into amyloidogenic aggregates represent an intriguing dimension in the pathophysiology of metabolic disorders, including alkaptonuria, canavan disease, and isovaleric acidemia. Central to this phenomenon are the metabolites homogentisic acid (HA), N-acetyl aspartic acid (NAA), and isovaleric acid (IVA), which we found, weave an intricate network of self-assembled structures. Leveraging an array of microscopy techniques, we traced the morphological behavior of these assemblies that exhibit concentration and time-dependent morphological transitions from isolated globules to clustered aggregates. MD simulation studies suggest significant role of hydrogen bonding interactions in the aggregation process. While displaying strong amyloidogenic propensity in solution, these aged aggregates were significantly cytotoxic to mouse neural N2a cell lines. In vivo effect in Caenorhabditis elegans (C. elegans) nematode further validated cytotoxicity of aggregates. Our findings provide fresh insights to amyloidogenic nature of HA, NAA, and IVA aggregates and their possible role in associated metabolic disorders such as alkaptonuria, canavan disease and isovaleric acidemia.

High stability of charged particle clusters in protoplanetary disks

Context. The initial particle growth in protoplanetary disks is limited by a bouncing barrier at submillimeter wavelengths. Bouncing leads to tribocharging and the electrostatic attraction of tribocharged aggregates may eventually draw them into large clusters. A charge- mediated growth phase allows for the formation of larger entities, namely, clusters of aggregates that are more prone to further particle concentrations, such as the streaming instability. Aims. We aim to quantify the strength of the electrostatic forces. Methods. In laboratory experiments, we used an acoustic trap to levitate small aggregates of tribocharged submm grains. These aggregates spin up within the trap until they lose grains. Thus, we used the centrifugal force as a measure of the local force. Results. Grains are regularly bound strongly to their neighbors. In comparison, the force at ejection can be stronger than the attractive scattering forces of the trap and can therefore be several orders of magnitude larger than expected. We note that these forces are long- ranging, compared to van der Waals forces. Thus, charged aggregates are much more stable than uncharged ones. Conclusions. Particle aggregates in disks might grow to centimeter clusters or larger as tribocharging increases the effective binding forces. This allows for hydrodynamic concentration and planetesimal formation to eventually take place throughout a wide part of the disk.

Morphology and inter-vesicle distances in condensates of synaptic vesicles and synapsin

Synaptic vesicle clusters or pools are functionally important constituents of chemical synapses. In the so-called reserve and the active pools, neurotransmitter-loaded synaptic vesicles (SVs) are stored and conditioned for fusion with the synaptic membrane and subsequent neurotransmitter release during synaptic activity. Vesicle clusters can be considered as so-called membrane-less compartments, which form by liquid-liquid phase separation (LLPS). Synapsin as one of the most abundant synaptic proteins has been identified as a major driver of pool formation. It has been shown to induce LLPS and form condensates on its own in solution, but also has been shown to integrate vesicles into condensates in vitro. In this process, the intrinsically disordered region of synapsin is believed to play a critical role. Here we first investigate the solution structure of synapsin and SVs separately by small-angle X-ray scattering (SAXS). In the limit of low momentum transfer q, the scattering curve for synapsin gives clear indication for supra-molecular aggregation (condensation). We then study mixtures of SVs and synapsin forming condensates, aiming at the morphology and inter-vesicle distances, i.e the structure of the condensates in solution. To obtain the structure factor S(q) quantifying inter-vesicle correlation, we divide the scattering curve of condensates by that of pure SV suspensions. Analysis of S(q) in combination with numerical simulations of cluster aggregation indicates a non-compact fractal-like vesicular fluid with rather short inter-vesicle distances at the contact sites.

Fracture of polymer-like networks with hybrid bond strengths

The design and functionality of polymeric materials hinge on failure resistance. While molecular-level details drive crack evolution in polymer networks, the connection between individual chain scission and bulk failure remains unclear and difficult to probe. In this work, we systematically study the fracture mechanics of polymer-like networks with hybrid bond strengths. We reveal that varying the ratio of strong and weak strands within otherwise identical networks gives a non-monotonic relationship between intrinsic fracture energy and strong strand fraction. Networks with some weak strands can counterintuitively outperform those with exclusively strong strands. Experiments on poly(ethylene glycol) gels and architected polymer-like lattices together with simulations unveil these properties. We show through computational visualization that strand type concentrations impact crack growth patterns and fracture energy trends. Cracks propagate through weak layers at low strong strand fractions. Aggregate clusters deflect or pin cracks at similar concentrations of strong and weak strands. Cracks blunt due to dispersed weak strand failure at high strong strand fractions. The sacrificial weak strands can notably deconcentrate stress near the crack tip, which toughens by delaying crack advancement. The interplay between concentration and clustering of strand types in networks with hybrid bond strengths, combined with crack growth phenomena and nonlocal energy release, provides insights into unusual fracture characteristics. Results shed light on fracture in polymer networks and percolated lattices.

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.

Study on the morphological characteristics of coal particle flocs under fractal theory

Based on fractal theory, the geometric size, surface morphology, and spatial structure of flocs in the hydrophobic flocculation process of coal particles were examined via particle size distribution detection, image analysis technology, and numerical simulation. The floc size distribution curve was classified and discussed via the dual-domain fractal rule, and the variation law of the composition and distribution of the coarse- and fine-grained coal particle flocs with the flocculation process was clarified. The various levels and characteristics of the floc growth geometry were explained by the analysis of the fractal dimension of the individual floc surface and the multiple spectra of the floc groups in the metallographic microscopy image. The hydrophobic flocculation process of coal particles was simulated via the diffusion-limited cluster aggregation model. The gyration fractal dimension was used to examine floc fragmentation and reconstruction and clarify the growth law of the floc spatial structure during the hydrophobic flocculation process.

Clusters of African countries based on the social contacts and associated socioeconomic indicators relevant to the spread of the epidemic

IntroductionIt is well known that social contact patterns differ from country to country. This variation coincides with significant socioeconomic heterogeneity that complicates the design of effective nonpharmaceutical interventions. This study examined how socioeconomic heterogeneity in selected African countries might be factored in to explain better patterns of social contact mix between countries.MethodsWe used a standardized contact matrix for 32 African countries, estimated in (Prem et al. in PLoS Comput Biol 17(7):e1009098, 2021). We scaled the matrices using an epidemic model from (Röst et al. in Viruses 12(7):708, 2020). We also analyzed aggregated data from the World Bank country website. The data includes 28 variables; social, economic, environmental, institutional, governance, health and well-being, education, gender inequality, and other development-related indicators that describe countries. Principal component analysis was used to visualize socioeconomic similarities between countries and identify the indicators for maximum variation. The (2D)2PCA\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$(2D)^{2} PCA$\\end{document} approach was used to reduce the dimension of synthetic contact matrices for each country to avoid the dimensionality curse. Then, hierarchical aggregate clustering was used to identify groups of countries with similar social patterns, taking into account the country’s socioeconomic performance.ResultsOur model yielded four meaningful clusters, each with a few distinguishing features. Social contacts varied between groups, but were generally similar within each set. The socioeconomic performance of the country influenced the clusters.ConclusionsOur results suggest that integrating socioeconomic factors into social contacts can better explain infectious disease transmission dynamics and that similar interventions can be implemented in countries within the cluster

The role of cross-linkers in the performance of anion exchange membrane for fuel cell applications

Anion exchange membranes (AEMs) with high OH- conductivity, good alkaline stability, and dimensional stability are still challenges for AEM fuel cells to be used in practice. In this study, high-performance cross-linked AEMs are developed. To construct the hydrophilic ionic channels, a series of polysulfone-based cross-linked AEMs were prepared utilizing the DABDA cation and two distinct cross-linkers (one with ether and one without ether). The cross-linking process enhanced aggregation of ion clusters, which resulted in the formation of ion-conductive channels and phase-separated hydrophilic/hydrophobic morphology, as well as enhancing the dimensional stability of the AEMs. The produced AEMs demonstrated good conductivity relative to their swelling ratio at 70 °C, and high conductivity in the range of 19.6–46.7 mS/cm between 25 and 70 °C. Additionally, the cross-linked AEMs revealed enhanced alkaline, mechanical and thermal stability. This work presents a promising strategy for developing high-efficiency AEMs for fuel cells.

Super-resolution imaging reveals the role of DDR1 cluster in NSCLC proliferation

Discoidin domain receptor 1 (DDR1), a transmembrane protein, is crucial in tumor development. Prior studies have demonstrated a significant correlation between protein cluster distribution on the cell membrane and tumor evolution. However, the precise spatial distribution characteristics of DDR1 on cell membranes and their impact on tumor development remain unclear. In this study, we conducted gene expression analysis to investigate DDR1 expression in non-small cell lung cancer (NSCLC) and its association with patient prognosis. We also employed direct stochastic optical reconstruction microscopy (dSTORM) imaging to examine DDR1's spatial distribution in NSCLC cells and tissues. Our findings indicate that DDR1 forms larger, tighter, and more abundant clusters in cancer cells and tissues compared to their normal counterparts. Notably, we observed that the enhanced aggregation of DDR1 clusters increased the likelihood of interaction with SRC, thereby activating the SRC-STAT3 signaling pathway in NSCLC cells and promoting cell proliferation. This study provides novel insights into the role of DDR1 aggregation in tumor proliferation, confirms DDR1 as a potential tumor marker, and serves as a valuable resource for future drug development.

Jellyfish-Inspired Polyurea Ionogel with Mechanical Robustness, Self-Healing, and Fluorescence Enabled by Hyperbranched Cluster Aggregates.

Ionogels are promising for soft iontronics, with their network structure playing a pivotal role in determining their performance and potential applications. However, simultaneously achieving mechanical toughness, low hysteresis, self-healing, and fluorescence using existing network structures is challenging. Drawing inspiration from jellyfish, we propose a novel hierarchical crosslinking network structure design for in situ formation of hyperbranched cluster aggregates (HCA) to fabricate polyurea ionogels to overcome these challenges. Leveraging the disparate reactivity of isocyanate groups, we induce the in situ formation of HCA through competing reactions, enhancing toughness and imparting the clustering-triggered emission of ionogel. This synergy between supramolecular interactions in the network and plasticizing effect in ionic liquid leads to reduced hysteresis of the ionogel. Furthermore, the incorporation of NCO-terminated prepolymer with dynamic oxime-urethane bonds (NPU) enables self-healing and enhances stretchability. Our investigations highlight the significant influence of HCA on ionogel performance, showcasing mechanical robustness including high strength (3.5 MPa), exceptional toughness (5.5 MJ m-3), resistance to puncture, and low hysteresis, self-healing, as well as fluorescence, surpassing conventional dynamic crosslinking approaches. This network design strategy is versatile and can meet the various demands of flexible electronics applications.

Evaluation of the protection of astaxanthin on human hair follicle palilla cells against the aging effects triggered by hydrogen peroxide

Astaxanthin (ASX) is a powerful antioxidant with high efficacy in inhibiting reactive oxygen species (ROS), one of the most harmful factors leading to hair loss. Our research specifically evaluated the ability of ASX to protect human dermal papillae cells from hydrogen peroxide (H2O2). In this study, the human dermal papillae (hDP) cells were successfully isolated. The cells expressed DP cell markers in the 2D model, including alkaline phosphatase, alpha-smooth muscle actin (98.66 ± 0.02%), and vimentin (98.88 ± 0.02%), cluster aggregation and spheroid formation in the 3D model. The hDP cells (P3-P5) were pretreated with ASX and subsequently treated with H2O2 at a concentration of 550 µM for 4 hours. After 4 days of treatment, the percentage of cells expressing the marker b-galactosidase decreased from 87 ± 0.01% in the control group to 27.61 ± 0.01% in the ASX-treated group (1 µg/mL). Our results indicated that astaxanthin effectively protects against oxidative stress in dermal papillae cells, suggesting its potential application in hair loss treatment due to ROS.

Energy Efficient Secured PSO Optimized Clustering and Data Aggregation Routing Protocol for Wireless Sensor Networks

In Wireless Sensor Networks (WSNs), sensor nodes are placed to sense and collect data. Due to the energy constraint nature of WSN, optimising the energy during the data dissemination is a major concern. To solve this problem, data aggregation may be used to bring down the redundant transmission of packets in WSN. In most of the previously available techniques, security is also a major concern during data aggregation and routing process with optimized energy. Many data aggregation-based routing systems are subject to security attacks during the data transfer from sensors to source to Clustered Heads (CHs) and then to sink with data aggregation process. Moreover, the existing data aggregation-based routing protocols suffer from data redundancy with less accuracy in aggregated data. For handling such issues order to overcome these issues, an Energy Efficient Secured Clustered Particle Swarm Optimization (PSO) oriented Data Aggregation Routing Protocol (EESCPSO-DARP) that can provide efficient authentication during data aggregation-based routing is introduced in this paper. Moreover, the proposed protocol enhances the rate of the data transmission by efficient prevention of false data injection and other attacks through node authentication and data encryption. This proposed protocol minimizes the energy usage by minimizing the retransmissions by eliminating the possible redundant transmissions of data during data aggregation-based routing. Moreover, the introduced protocol minimizes both communication and computational overhead through optimal clustering and routing with PSO and provides and efficient routing system. This proposed EESCPSO-DARP protocol has been developed by using the NS3 simulator. The results of this protocol showed improved security, higher packet delivery ratio and enhanced network throughput with reduced energy and delay.

Electrolyte Solvation Engineering Stabilizing Anode-Free Sodium Metal Battery With 4.0V-Class Layered Oxide Cathode.

Anode-free sodium metal batteries (AFSMBs) are regarded as the "ceiling" for current sodium-based batteries. However, their practical application is hindered by the unstable electrolyte and interfacial chemistry at the high-voltage cathode and anode-free side, especially under extreme temperature conditions. Here, an advanced electrolyte design strategy based on electrolyte solvation engineering is presented, which shapes a weakly solvating anion-stabilized (WSAS) electrolyte by balancing the interaction between the Na+-solvent and Na+-anion. The special interaction constructs rich contact ion pairs (CIPs) /aggregates (AGGs) clusters at the electrode/electrolyte interface during the dynamic solvation process which facilitates the formation of a uniform and stable interfacial layer, enabling highly stable cycling of 4.0V-class layered oxide cathode from -40°C to 60°C and excellent reversibility of Na plating/stripping with an ultrahigh average CE of 99.89%. Ultimately, industrial multi-layer anode-free pouch cells using the WSAS electrolyte achieve 80% capacity remaining after 50 cycles and even deliver 74.3% capacity at -30°C. This work takes a pivotal step for the further development of high-energy-density Na batteries.

A closer look at individual collisions of dust aggregates: material mixing and exchange on microscopic scales

ABSTRACT Collisions between aggregates with different histories and compositions are expected to be commonplace in dynamically active protoplanetary discs. None the less, relatively little is known about how collisions themselves may contribute to the resulting mixing of material. Here, we use state-of-the-art granular dynamics simulations to investigate mixing between target/projectile material in a variety of individual aggregate-aggregate collisions, and use the results to discuss the efficiency of collisional mixing in protoplanetary environments. We consider sticking collisions (up to 10–20 m s–1 for our set-up) and disruptive collisions (40 m s–1) of ballistic particle–cluster aggregation (BPCA) and ballistic cluster–cluster aggregation (BCCA) clusters, and quantify mixing in the resulting fragments on both individual fragment and sub-aggregate levels. We find that the mass fraction of material that can be considered to be ‘well-mixed’ (i.e. locally made up of a mix of target and projectile material) to be limited, typically between 3 and 6 per cent for compact BPCA precursors, and increasing to 20–30 per cent for more porous BCCA clusters. The larger fragments produced in disruptive collisions are equally heterogeneous, suggesting aggregate–aggregate collisions are a relatively inefficient way of mixing material with different origins on small scales.

Nonequilibrium cluster-cluster aggregation in the presence of anchoring sites.

Nonequilibrium cluster-cluster aggregation of particles diffusing in or at the cell membrane has been hypothesized to lead to domains of finite size in different biological contexts, such as lipid rafts, cell adhesion complexes, or postsynaptic domains in neurons. In this scenario, the desorption of particles balances a continuous flux to the membrane, imposing a cutoff on possible aggregate sizes and giving rise to a stationary size distribution. Here, we investigate the case of nonequilibrium cluster-cluster aggregation in two dimensions where diffusing particles and/or clusters remain fixed in space at specific anchoring sites, which should be particularly relevant for synapses but may also be present in other biological or physical systems. Using an effective mean-field description of the concentration field around anchored clusters, we derive an expression for their average size as a function of parameters such as the anchoring site density. We furthermore propose and solve appropriate rate equationsthat allow us to predict the size distributions of both diffusing and fixed clusters. We confirm our results with particle-based simulations and discuss potential implications for biological and physical systems.

Distortion Engineering: A Strategy to Modulate Molecular Upconversion with Molecular Cluster-Aggregates.

The rational engineering of molecules is a powerful chemistry tool of pivotal importance in the fields of molecular magnetism and luminescence. Hence, systems that can be modulated via molecular engineering and composition control are expected to present extra versatility regarding the tunability of their properties. This is the case with molecular cluster aggregates (MCAs), high nuclearity molecular compounds. Herein, we demonstrate how the union of both strategies, namely, composition control and molecular engineering, can be employed to enhance molecular upconversion in MCAs. This was achieved by doping a {Gd8Er2Yb10} MCA with CeIII ions. By replacement of the optically silent GdIII ions with CeIII, the upconversion mechanism is modified due to CeIII-mediated cross-relaxation. In addition to this effect, we could also engineer the degree of metal site distortion due to the larger size of CeIII ions, relaxing the selection rules and impacting the upconversion quantum yield and luminescent thermometry. Opto-structural correlations demonstrate that the presented molecular engineering strategy can be used to enhance the performance of molecular upconverters.

Mesoscopic structure modeling of silica aerogels using cluster‐cluster aggregation

AbstractSilica aerogels are nanostructured materials known for their low density, high porosity, and excellent thermal insulation properties. Among silica aerogels, organosilane‐derived aerogels have received considerable interest for their additional chemical functionalities such as hydrophobicity and flexibility. This work investigates the mesoscopic modeling of such aerogels, extending an aggregation based model developed for conventional silica aerogels. The pH of sol–gel polymerizations is one of the most critical reaction and processing parameters in determining the porosity, density, strength, and transparency of the resulting gels. Achieving optical transparency in aerogels depends on the presence of homogeneous mesoporous network structures. To account for the effect of pH, a relationship between pH and adhesion probability was incorporated into a three‐dimensional cluster‐cluster aggregation (CCA) model, providing insight into the gelation process. In addition, size‐dependent diffusivities are considered in this study. By incorporating different factors into the CCA model, the gelation kinetics are evaluated. The obtained mesoscopic structure is compared with experimental characterizations, together with preliminary mechanical simulations.

PSLBII-30 The effect of different soybean meal batches and protease supplementation on nutrient utilization by broiler chickens

Abstract Soybean meal (SBM) is the major protein source in broiler chicken diets. However, the thermal processing of SBM may have an impact on its protein quality, reducing its solubility when over-processed. In this context, the use of exogenous protease may reduce the negative effects that the over-processing of SBM may have on protein digestibility in broiler chickens. The present study investigated two batches of SBM in broiler chicken diets supplemented or not with protease. One-d-old male Cobb 500 (n = 360) were randomly distributed in a 2 x 2 factorial arrangement (SBM batches: A and B; Protease inclusion: 0 and 50 g/t of diet). SBM protein quality was evaluated through crude protein (CP), KOH solubility, and urease activity test (UA) in batches A and B. Scanning electron microscopy was used to visualize the structural organization of particles from SBM A and B. On d 26, ileal digesta content was collected from 6 broiler chickens that were euthanized to determine the apparent ileal digestibility (AID) of dry matter (DM), crude protein (CP), and ileal digestible energy (IDE). Data obtained were submitted to ANOVA and means were compared by Tukey test with a significance declared of 5% using the GLM procedure on R Software. Protein quality assessment demonstrated KOH solubility of 85% and 75% for SBM from batches A and B, respectively. For UA analysis, SBM batch A presented 0.09 and batch B of 0.01 mg N/g (Table 1). Microscopy images emphasized visual differences in particles from batches A and B. In SBM particles from batch A, disorganized cluster structures and asymmetric pores were observed, whereas in the SBM particles from batch B, insignificant pores and large cluster aggregates were visualized in a denser structure (Figure 1). The SBM batch B presented decreased AID of DM, CP, and IDE (P < 0.05). Protease supplementation improved the AID of CP (P < 0.05) in broilers at 26 d of age, regardless of SBM batches, but no effect was observed for DM and IDE (P > 0.05; Table 2). In conclusion, SBM from batch A had greater values of KOH solubility and UA, suggesting an appropriate thermal process, and ensuring protein quality, which is demonstrated through improvement in nutrient utilization by broiler chickens. The use of 50 g of exogenous protease per t of diet improved the ileal digestibility of CP, regardless of SBM batches.

Effects of Moisture Content on the Radiative Properties and Energy-Saving Performance of Silica Aerogel Windows.

The thermal insulation performance of windows is crucial for energy-efficient buildings. Windows are typically the weakest part of the building envelope, regarding thermal insulation. Due to its excellent thermal insulation and high transparency, silica aerogel shows great promise as a window material. However, moisture can impact the effectiveness of the aerogel, leading to poor visibility and reduced thermal insulation. This study simulated a silica aerogel with varying moisture levels using the combination of diffusion-limited cluster aggregation, discrete dipole approximation, and Monte Carlo methods. The effects of the moisture content, thickness, porosity, and particle size on thermal conductivity, solar transmittance, and haze were analyzed. Visual properties of the aerogels were also considered. The energy consumption of a 30 m2 room under different climates was simulated using TRNSYS to assess the energy-saving potential of silica aerogel glass. The findings indicate that a higher moisture content leads to decreased solar transmittance and increased thermal conductivity of aerogels. Silica aerogel glass is more energy efficient than single-layer float glass, with the dry aerogel performing better in cold climates but worse in hot climates. This study provides insights for designing aerogel glass that optimizes solar transmittance and thermal insulation to enhance building comfort and energy efficiency.