Cluster Aggregation Research Articles

Fractal Scaling in the Gas-Phase Agglomeration of Nanowires.

Assembling1D nanoparticles (nanowires (NW) or nanotubes) as networks enables bridging multiple scales to form macroscopic materials such as fibers, sheets and electrodes. This can be done directly in the gas phase from 1D nanoparticle aerosols grown by floating catalyst chemical vapor deposition (FCCVD). In FCCVD nanowires/nanotubes grow to high aspect ratios (102-106) floating in a gas stream and can agglomerate to form an aerogel. This work studies the agglomeration of Si nanowires by scanning electron microscopy of samples taken from the gas downstream of the reaction zone, and through simulations with a Brownian collision algorithm to form agglomerate models. In the experimental analysis of over 312 samples no individualized NWs are found, only agglomerates. This is consistent with the fast binary collision rates of 0.24 s estimated. The agglomerates show "fractal" scaling, with a fractional dimension Df of 1.8 and agglomerate size increasing with the number of nanowires to the power of 1/Df, consistent with a diffusion limited cluster aggregation process. Formation of a nanowire aerogel involves percolation of agglomerates, therefore occurring at much lower volume fraction than for individualized particles considering excluded volume theory. Compared to FCCVD carbon nanotubes of higher aspect ratio, these SiNWs require longer residence time for gelation.

Feasibility of online optical diagnostics during gas-phase synthesis of few-layer graphene based on elastic light scattering measurements

Gas-phase synthesis is a promising method for scalable production of high-quality free-standing few-layer graphene (FLG) particles. This study assesses the feasibility of elastic light scattering in characterizing particle morphology and distinguishing FLG from soot-like particles that may also be produced concurrently during gas-phase synthesis. FLG particle morphology is modeled based on tomographic electron microscopy images of FLG particles produced within a plasma reactor, whereas synthetic soot particles are generated via a cluster–cluster aggregation algorithm based on morphological parameters typical of flame soot. Light scattering properties of ensembles of synthetic FLG and soot particles are simulated via the discrete dipole approximation (DDA) and the multi-sphere T-matrix method, respectively. Angle-resolved scattering properties of ensembles of FLG and soot particles are analyzed to evaluate the feasibility of scattering-based diagnostics and identify potential measurement configurations for characterizing particle morphology. Overall, certain scattering properties, especially the depolarization ratio, are observed to be sensitive to the distinctive morphological aspects of FLG and soot, which highlights the promise of light scattering-based diagnostics for characterizing morphology during gas-phase synthesis of FLG.

The Impact of Targeted Therapies on Red Blood Cell Aggregation in Patients with Chronic Lymphocytic Leukemia Evaluated Using Software Image Flow Analysis.

Chronic lymphocytic leukemia (CLL), the most common type of leukemia, remains incurable with conventional therapy. Despite advances in therapies targeting Bruton's tyrosine kinase and anti-apoptotic protein BCL-2, little is known about their effect on red blood cell (RBC) aggregation in blood flow. In this study, we applied a microfluidic device and a newly developed Software Image Flow Analysis to assess the extent of RBC aggregation in CLL patients and to elucidate the hemorheological effects of the commonly applied therapeutics Obinutuzumab/Venetoclax and Ibrutinib. The results revealed that, in RBC samples from untreated CLL patients, complex 3D clusters of large RBC aggregates are formed, and their number is significantly increased compared to healthy control samples. The application of the Obinutuzumab/Venetoclax combination did not affect this aspect of RBCs' rheological behavior. In contrast, targeted therapy with Ibrutinib preserves the aggregation state of CLL RBCs to levels seen in healthy controls, demonstrating that Ibrutinib mitigates the alterations in the rheological properties of RBCs associated with CLL. Our findings highlight the alterations in RBC aggregation in CLL and the impact of different targeted therapies on RBCs' rheological properties, which is critical for predicting the potential complications and side effects of CLL treatments, particularly concerning blood flow dynamics.

Mapping the landscape of Hospital at home (HaH) care: a validated taxonomy for HaH care model classification

BackgroundHospital at home (HaH) care models have gained significant attention due to their potential to reduce healthcare costs, improve patient satisfaction, and lower readmission rates. However, the lack of a standardized classification system has hindered systematic evaluation and comparison of these models. Taxonomies serve as classification systems that simplify complexity and enhance understanding within a specific domain.ObjectiveThis paper introduces a comprehensive taxonomy of HaH care models, aiming to categorize and compare the various ways HaH services are delivered as an alternative to traditional hospital care.MethodsWe developed a taxonomy of characteristics for HaH care models based on scientific literature and by applying a taxonomy development framework. To validate the taxonomy, and to analyze the current landscape of HaH models we matched the taxonomy to HaH care models described in literature. Finally, to identify types of HaH care implementations, we applied the k-means clustering method to care models represented using the taxonomy.ResultsOur taxonomy consists of 12 unique dimensions structured into 5 perspectives following the progression from triaging, through care delivery, operational processes, and metrics for success: Persons and roles (2 dimensions), Target population (1 dimension), Service delivery and care model (6 dimensions), outcomes and quality metrics (2 dimensions), and training and education (1 dimension). Cluster analysis of 34 HaH care models revealed three distinct types: One cluster (50%, 17/34) focuses on patient eligibility and home environment suitability, a care model to be chosen for clinically complex patients. A second cluster (29.4%, 10/34) aggregates technology-enabled models using telemedicine and remote monitoring that are adaptable across settings. This type could be chosen for generalizable care. The third cluster (20.6%, 7/34) includes complex interventions involving informal caregivers and advanced medical devices, requiring caregiver training, supportive policies, and user-friendly technology to reduce caregiver burden and improve safety.ConclusionsThe clusters identified highlight practical considerations for adapting HaH care approaches to patient and contextual needs. These findings can guide policymakers in developing guidelines and assist practitioners in tailoring HaH care models to specific patient populations. The challenges encountered in collecting information on different characteristics of the taxonomy underscore the urgent need for more comprehensive and standardized reporting in scientific papers on HaH interventions.

Cortical Tau Aggregation Patterns Associated With Apraxia in Patients With Alzheimer Disease.

Apraxia is a frequently observed symptom in Alzheimer disease (AD), but the causal pathomechanism underlying this dysfunction is not well understood. Previous studies have demonstrated associations between various cognitive dysfunctions in AD and cortical tau deposition in specific brain areas, suggesting a causal relationship. Thus, we hypothesized that specific regional patterns of tau pathology in praxis-related brain regions may be associated with apraxic deficits in AD. For this purpose, we performed PET imaging with the second-generation tau-PET tracer [18F]PI-2620 in a well-defined group of patients with AD (N = 33) who had been systematically assessed for apraxia. Patients with a biomarker-confirmed diagnosis of AD were recruited in addition to a sample of cognitively unimpaired (CU1) control participants. Both groups underwent apraxia assessments with the Dementia Apraxia Screening Test. In addition, PET imaging with [18F]PI-2620 was performed to assess tau pathology in the patients with AD. To specifically investigate the association of apraxia severity with regional tau pathology, we compared the PET data from this group with an independent sample of amyloid-negative cognitively intact participants (CU2) by generation of z-score deviation maps and submitted these maps to a voxel-based multiple regression analysis. A total of 120 participants (39% female) with a mean age of 67.9 (9.2) years were included in the study (AD = 33; CU1; N = 33; CU2; N = 54). We identified a significant correlation between circumscribed clusters of tau aggregation in praxis-related brain regions (including parietal (angular gyrus), temporal, and occipital regions) and severity of apraxia in patients with AD. By contrast, no significant correlations between tau tracer uptake in primary motor cortex or subcortical brain regions and apraxia were observed. These results suggest that tau deposition in specific cortical praxis-related brain regions may induce local neuronal dysfunction leading to a dose-dependent functional decline in praxis performance in AD. The awareness of this relationship could further refine a differentiated individual diagnostic characterization and classification of patients with AD.

Evolutionary characteristics, regional differences and spatial effects of coupled coordination of rural revitalization, new-type urbanization and ecological environment in China

Rural revitalization (R), new-type urbanization (U) and the ecological environment (E) are a unity of complementary advantages and mutual promotion and coexistence, the coupling and coordination of the three is the key to realizing the Chinese modernization and the harmonious coexistence of human beings and nature. Based on China’s provincial panel data from 2011 to 2022, this paper constructed a comprehensive evaluation index for the R-U-E system, using the entropy method, coupled coordination model, Dagum’s Gini coefficient, kernel density estimation, spatial correlation analysis, and spatial Durbin model to explore the level of comprehensive development, spatial-temporal evolutionary characteristics of coupled coordination, regional differences and spatial effects of the three systems. The following results were observed: (1) The comprehensive index of rural revitalizationand new-type urbanization exhibits a growing trend and significant regional differences, with East China outperforming other regions, but the average value of below 0.5 needs to be further improved. The ecological environment index exhibits a smoother growth trend, higher in South China than in other regions. (2) The level of R-U-E coupling coordination has increased year on year, from barely coordinated to primary coordination. (3) The spatial imbalance in coupling coordination has improved both nationally and in the seven regions, with the largest intra-regional differences in South China and the smallest intra-regional differences in Central China. The differences between the Northeast and Central China regions exhibit a widening trend, while the differences between all other regions exhibit a decreasing trend. Interregional variations are the main factor affecting overall variance, but their impact on the overall variance is gradually diminishing. (4) The level of coupling coordination has obvious spatial correlation, and the “high-high” and “low-low” cluster aggregation characteristics was evident. (5) Government behavior and the levels of economic growth, human capital, and digitization significantly contribute to the coupled and coordinated development of the region and, at the same time, have a significant spatial spillover effect on neighboring provinces; the degree of openness to the outside world contributed to the coordinated development of the region, while it had an inhibitory effect on the neighboring provinces; and the drive to innovate has only a certain contributing effect on the neighboring regions. Targeted policy measures in response to this paper’s empirical findings may provide policymakers with a reference point for achieving regional sustainable development goals.

Going beyond cell clustering and feature aggregation: Is there single cell level information in single-cell ATAC-seq data?

1Single-cell Assay for Transposase Accessible Chromatin with sequencing (scATAC-seq) has become a widely used method for investigating chromatin accessibility at single-cell resolution. However, the resulting data is highly sparse with most data entries being zeros. As such, currently available computational methods for scATAC-seq feature a range of transformation procedures to extract meaningful information from the sparse data. Most notably, these transformations can be categorized into: 1) feature aggregation with known biological associations, 2) pseudo-bulking cells of similar biology, and 3) binarisation of count data. These strategies beg the question of whether or not scATAC-seq data actually has usable single-cell and single-region information as intended from the assay. If we can go beyond aggregated features and pooled cells, it opens up the possibility of more complex statistical tasks that require that degree of granularity. To reach the finest possible resolution of single-cell, single-region information there are inevitably many computational challenges to overcome. Here, we review the major data analysis challenges lying between raw data readout and biological discovery, and discuss the limitations of current data analysis approaches. Lastly, we conclude that chromatin accessibility profiling at true single-cell resolution is not yet achieved with current technology, but that it may be achieved with promising developments in optimising the efficiency of scATAC-seq assays.

INFLUENCE OF INTERLEUKIN-2 AND INTERFERON-α ON LYMPHOCYTE AGGREGATION AND LYMPHOCYTE-PLATELET CLUSTER FORMATION

The aim of the research was to study the direct and platelet-mediated intercellular adhesion of blood-derived lymphocytes, as well as the influence of interleukin-2 and interferon-α on it.Materials and methods. Whole blood samples from 34 apparently healthy individuals were collected using vacuum tubes containing sodium citrate (3,8%). A suspension of lymphocytes and platelets was isolated on a Ficoll-Urografin gradient. Light microscopy was used to determine the percentage of lymphocyte-platelet aggregates. The effect of cytokines was studied by adding human recombinant interleukin-2 and interferon-α to whole blood, and incubating for 4 hours in a thermostat at 37 °C. After incubation the necessary parameters were counted using the method described above. The results were expressed as mean values and standard deviations (± SD). Statistical processing of the data was performed using the Mann-Whitney U-test and the Kolmogorov criterion (Statistica 10), with differences considered significant at p < 0.05.Results. The study showed that in addition to lymphocyte-platelet aggregates (11 ± 3.6%), the total pool of lymphocytes also contained intercellular aggregates of lymphocytes (3 ± 3,8 per 100 cells) and lymphocyteplatelet clusters (2 ± 0,6 per 100 cells). It was found that the addition of interleukin-2 (IL-2) led to an increase in lymphocyte-platelet aggregates (LPA) and lymphocyte-platelet clusters by 1,8 times (p < 0,001) and 3,3 times (p < 0,001), respectively, compared to the control group. In contrast, incubation of blood samples with interferon-α (IFN-α) led to a decrease in the number of LPA (by 5.5 times compared to the control, p < 0,001) and almost prevented the ability of lymphocytes and platelets to form clusters. The presence of the abovementioned cytokines in the incubated blood did not affect the ability of lymphocytes to form aggregates with each other.Сonclusion. It was found that IL-2 increases the ability of lymphocytes and platelets to form clusters, while IFN-α significantly reduces this ability and has an inhibitory effect on the ability of these cells to form LPA. In our opinion, it is important that the effects of these cytokines were manifested only upon contact of lymphocytes with platelets.

Biotic agents of tufa formation in сarbon dioxide enriched hard-water springs of Mizhhirya basin and adjacent territories

The main groups of biote and their functional role in the calcareous tufa formation at the hard-water springs enriched by carbon dioxide of the Mizhhirya basin and adjacent territories were investigated. It has been studied that in the formation of calcareous tufa of all surveyed locations, representatives of micro-, bryo and phytobiota play an important role, and therefore, the studied sedimentary rock are mainly biogenic in their origin. Microbiota agents, mainly cyanobacteria of the order Oscillatoriales, play a leading role in the initial acts of calcareous tufa accumulation (stage I). These bacteriogenic initial forms, which can be defined as initial thromboids, are represented by small- or medium-grained, ocher-yellow aggregates of a spherical shape, with a diameter of 0.5-2 mm, which actively accumulate at the springs exits. These congestions (mesoclots) are growing and compacting over time and forming weakly cemented thrombolites, which are a cluster of separate aggregates together with particles of sand, silt, rocks, plant remains, etc. The next post-pioneer stage (II) is marked by the appearance of specialized amphibious Bryophytes vegetation of the Pellion endiviifoliae alliance and pioneer caliciophilic vegetation of the Grimmaldion fragrantis alliance. In the formation of calcareous tufa deposits of the next stage (III), the leading role is played by the Bryophytes vegetation of the Pellion endiviifoliae alliance. Their mineralized turfs are modeling light, fragile and porous bryolithes of an ocher-brown color. Bryolithes usually contain seasonal layers richly encrusted with leaves of trees, which growing near the spring. Base on the specificity and ecological value of the biotic (calcicolous Bryobiota) and abiotic, primarily geological (calcareous iron tufa) component, the hard-water tufagenic springs of Mizhhirya Verkhovyna can be considered significant natural monuments of Transcarpathia region. However, regardless of the nature protection status of most hard-water iron springs (they are hydrological monuments of nature of local importance), they often suffer from human’s improvement, illegal water extraction, high recreational load etc. Thus, they need applicating of conservation measures and nature protection management planning.

Illite Dissolution under Sodium Hydroxide Solution: Insights from Reactive Molecular Dynamics.

In alkali/surfactant/polymer (ASP) flooding systems, alkalis react with clay minerals such as Illite, montmorillonite, and kaolinite, leading to reservoir damage and impacting oil recovery rates. Therefore, studying the dissolution effects of strong alkalis on clay minerals is crucial for improving oil recovery. This study uses Illite as a representative clay mineral and employs the ReaxFF reactive force field and molecular dynamics simulations to model its dissolution in NaOH solution. We investigated the diffusion coefficients of metal cations in Illite and their interactions with hydroxide ions at various NaOH concentrations. The study also explores the evolution of dissolution products and protonation characteristics during the dissolution of Illite. By calculating the changes in ionic energy throughout the dissolution process, we analyzed variations in ionic reactivity within the system. Simulation results show that as the NaOH concentration increases, metal cations in Illite form stable chemical bonds with hydroxide ions, creating highly aggregated clusters with strong ionic interactions that hinder migration. Consequently, the diffusion coefficients of metal cations gradually decrease. During the reaction, water dissociates to produce hydrogen ions and hydroxide ions. Ion exchange occurs between the solution cations and Illite cations. Illite cations gradually precipitate and form metal hydroxides by combining with hydroxide ions under electrostatic forces. Protonation propagates from the surface to the internal structure during the reaction. Moreover, the degree of protonation increases with higher NaOH concentrations. Changes in the average ionic energy before and after the reaction indicate that K+ exhibits the highest reactivity. Intermediate silicate products are unstable in NaOH solution, with some Si4+ ions showing higher energy and stronger reactivity.

Ecofriendly Synthesis of Nickel Oxide Nanoparticles From Fissidens Species and Its Biological Applications.

The present study was performed to synthesize eco-friendly nickel oxide nanoparticles (NiONPs) from the aqueous extract of Fissidens species (FS) and explore its biological activities. Phytochemicals, namely, alkaloids, flavonoids, sterols, tannins, proteins, carbohydrates and phenols, were present in the aqueous extract of Fissidens sp. The UV-Vis and FT-IR analyses of FS-NiONPs revealed a prominent peak at 392 nm, along with functional groups that facilitate the formation of FS-NiONPs. XRD spectrum confirmed the crystalline nature and SEM with EDX depicted the irregular, aggregated clusters and purity of FS-NiONPs. The photocatalytic activity against RB94 was achieved within 20 min with maximum decolorization efficiency (93%). The experimental data of adsorption studies fitted well with Langmuir isotherm, showcasing the monolayer adsorption of RB94 through chemisorption process. The thermodynamic study revealed that the dye removal was spontaneous, feasible and endothermic in nature. The results of antimicrobial activity and phytotoxicity study revealed the potentiality of FS-NiONPs in clinical and agricultural applications. Hence, this study emphasizes the eco-friendly synthesis of FS-NiONPs and highlights its decolorization potential, antimicrobial activity and growth promoting properties.

Interleukin-3 Modulates Macrophage Phagocytic Activity and Promotes Spinal Cord Injury Repair.

Effective clearance of lipid-rich debris by macrophages is critical for neural repair and regeneration after spinal cord injury (SCI). Interleukin-3 (IL-3) has been implicated in programming microglia to cluster and clear pathological aggregates in neurodegenerative disease. Yet, the influence of IL-3 on lipid debris clearance post-SCI is not well characterized. We established a mouse model of spinal cord compression injury to investigate the role of IL-3. Blockage of IL-3 was achieved through intrathecal delivery of an IL-3-neutralizing antibody, while IL-3 activation was augmented via insitu injection of recombinant IL-3 into the lesion site immediately post-SCI. Immunofluorescence staining was performed to determine IL-3 and IL-3Rα sources and distribution, lipid droplet accumulation, neuron preservation, and axon regeneration after SCI. The Basso Mouse Scale (BMS) and footprint analysis were employed to evaluate locomotor function recovery. We found that IL-3 expression was significantly upregulated post-SCI, peaking at 14 days post-injury (dpi) and persisting until 28 dpi. Notably, IL-3 was primarily secreted by astrocytes surrounding the lesion epicenter. Correspondingly, IL-3Rα was predominantly observed in macrophages within the injury core, also elevating at 14 dpi. Neutralization of IL-3 led to increased lipid droplet accumulation, along with markedly widespread of macrophages and decreased neuronal survival, resulting in severe motor deficits compared to controls. Conversely, insitu injection of IL-3 reduced lipid droplet accumulation in macrophages, preserved neurons, promoted axon regeneration, and ultimately contributed to the recovery of motor function after SCI. Our findings shed light on the role of IL-3 in modulating macrophage phagocytic activity and suggest that the IL-3/IL-3Rα pathway may be a potential therapeutic target for enhancing neural repair and functional recovery after SCI.

Quantifying the effects of the microphysical hygroscopic restructuring of soot on ensemble optical properties and satellite aerosol optical depth retrievals

Black carbon, or soot, significantly contributes to atmospheric light absorption due to its low single scattering albedo (SSA). This study investigates the impact of soot's hygroscopic restructuring on satellite remote sensing, focusing on radiative forcing, top-of-atmosphere (TOA) reflectance, and aerosol optical depth (AOD) retrievals. We characterized soot aging using relative humidity (RH) growth factor functions and modeled fresh and aging soot aggregates using a cluster-cluster aggregation algorithm. Bulk optical properties for each RH level were simulated using core-mantle generalized multi-sphere Mie-solution, weighted by the probability density function of soot monomer numbers. We incorporated soot aging models into the 6S radiative transfer model by adjusting the geometric mean radius of the soot component to match bulk SSA values at each aging degree. Extensive radiative transfer simulations were conducted, complemented by an analysis of 16 actual soot-containing cases in China from 2016 to 2019. Results showed that identical soot loads correspond to lower reflectance in dry environments and higher reflectance in humid environments. MODIS AOD retrieval errors approached zero when RH was close to 70 %, likely due to the similarity between the 6S default soot and the aging model at this humidity. Neglecting RH led to overestimations in AOD for cases with RH < 65 % and underestimations in high humidity cases (RH > 75 %). The average MODIS AOD retrieval errors for RH < 65 %, RH between 65 % and 75 %, and RH > 75 % were −33.15 %, −1.80 %, and +42.42 %, respectively. This study underscores the necessity of incorporating RH into satellite AOD retrieval algorithms to enhance accuracy and reduce uncertainties.

VMCFDGS: Variable Multicenter Aggregation Clustering Method Based on Fuzzy Dominating (Dominated)-Granularity Structure

VMCFDGS: Variable Multicenter Aggregation Clustering Method Based on Fuzzy Dominating (Dominated)-Granularity Structure

Coarse-Grained Molecular Dynamics Simulation of Ionomer-Mediated Carbon Cluster Bonding in Polymer Electrolyte Fuel Cell Catalyst Layers

In the field of sustainable energy technologies, Polymer Electrolyte Fuel Cells (PEFCs) represent a crucial advancement for achieving high-efficiency power generation. This study focuses on the specific behavior of ionomers within PEFCs, particularly how they facilitate the bonding of carbon clusters during the evaporation process, critical for the structural integrity and functionality of the catalyst layer.Amid the global shift toward a hydrogen economy, the development of robust and efficient PEFC technologies is imperative. The Nafion membrane, developed by DuPont, is the standard bearer for proton exchange membranes due to its superior proton conductivity, chemical stability, and durability. Despite these advantages, the performance of PEFCs under high temperature and low humidity conditions remains a challenge due to the reduced efficiency of proton transport. This research concentrates on the micro-mechanics of how ionomers assist in the bonding between carbon clusters during the drying stages of film formation, aiming to overcome this efficiency bottleneck.Employing Coarse-Grained Molecular Dynamics (CGMD) simulations, our study delves into the detailed interactions between ionomers and Pt-carbon clusters during evaporating solvents. The simulations use a refined computational model to capture the dynamic interplay during evaporation conceptualized as micro-differentiated boxes within the system as illustrated in Figure 1. These boxes allow for the analysis of ionomer behavior on a flat, graphene-sheet-modeled cluster surface adorned with Pt particles, assessing how different configurations influence structural and transport properties.This approach not only elucidates the role of ionomers in promoting the aggregation of carbon clusters during evaporation but also provides insight into the nuanced processes that govern the formation and stability of the catalyst layer. Initial simulations pointed out the need for adjustments in the force field settings, which were subsequently optimized to enhance the accuracy of the observations regarding ionomer distribution and bonding effectiveness during evaporation.With the foundational simulations set, future work will extend to exploring how various experimental conditions—such as solvent composition, and the size and density of platinum particles—affect ionomer bonding between carbon clusters. By adjusting these parameters systematically, we aim to define the optimal conditions that enhance the structural cohesion and functional performance of the catalyst layer.This investigation is expected to yield significant insights into the fundamental interactions and mechanisms at play in the bonding process, contributing to a deeper understanding of PEFC technology and leading to advancements in the production methods of these fuel cells. Ultimately, this research will help to refine and optimize the procedures for manufacturing more efficient and durable PEFCs, marking a substantial step toward more sustainable energy systems.AcknowledgmentThe New Energy and Industrial Technology Development Organization (NEDO) of Japan supported this work under Grant number NP20003.A part of the results was obtained by supercomputer system of Institute of Fluid Science, Tohoku University. Figure 1

[o-C2B10H10]3 as a trimer aggregate of spherical aromatic carboranes. Persistence and interplay between spherical aromatic states

Envisaging cluster-based materials requires a fundamental understanding of the aggregation processes and resulting properties. The inherent spherical aromatic properties of carboranes trigger further evaluation of the persistence of such property in the resulting cluster aggregate. Here, we evaluated the formation of a trimeric species based on the neutral [o-C2B10H12] cluster on the [o-C2B10H10]3 form. The obtained results show that the inherent spherical aromatic characteristics of the constituent building units remain in the resulting trimer aggregate as three spherical aromatic states. Thus, cluster-based materials can be envisaged from stable spherical aromatic units, guiding further experimental realization of cluster-based aggregates.

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.

Morphology and intervesicle 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 membraneless compartments, which form by liquid-liquid phase separation. 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 liquid-liquid phase separation 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. In the limit of low momentum transfer q, the scattering curve for synapsin gives clear indication for supramolecular aggregation (condensation). We then study mixtures of SVs and synapsin-forming condensates, aiming at the morphology and intervesicle distances, i.e., the structure of the condensates in solution. To obtain the structure factor S(q) quantifying intervesicle 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 noncompact fractal-like vesicular fluid with rather short intervesicle distances at the contact sites.

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.