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Electrodes with a maximal active site density are critical for high‐performance high‐temperature electrochemical cells (HTECs). One widely employed approach involves the use of porous nanostructures with a high surface‐to‐volume ratio. However, their active site densities inevitably decrease owing to particle aggregation induced at high temperatures, necessitating further development of electrode processing techniques. Taking Pt/yttria‐stabilized zirconia (YSZ) interface as a model system, a Pt nanostructured textile akin to the cantaloupe‐rind pattern with high mechanical integrity is fabricated. Application of an AC voltage to this textile electrode at an elevated temperature reduces the Pt particle size from submicron to 10–80 nm forming a nanocomposite with YSZ, accompanied by a 40‐fold increase in current density under high‐temperature water electrolysis conditions. Furthermore, the AC voltage application to a partially aggregated electrode restores its nano‐blended structure associated with the recovery of its activity. This technique is effective in counteracting particle aggregation on demand, providing an alternative approach to achieve high performance and extended lifetimes in HTECs. [ABSTRACT FROM AUTHOR]

With the rapid development of the phosphorus chemical industry and the new energy industry, the role of phosphate rock is becoming more and more prominent. Medium and low phosphorus ore has gradually become a research hotspot. The stable dispersion of fine-grained phosphate rock in pulp is the premise of effective flotation. To elucidate the mechanism through which fine-grained phosphate-rock particles disperse and aggregate in pulps, we used solution chemistry, Derjaguin–Landau–Verwey–Overbeek theoretical calculations, zeta-potential measurements, and x-ray photoelectron spectroscopy to investigate the effects of Ca2+, Mg2+, Fe3+, and Al3+ metallic ions on the dispersion stability during the flotation of medium- and low-grade phosphate-rock particles. The experimental results showed that as the pulp pH changed, the metallic ions differently inhibited the particle dispersion stability. The trivalent metallic ions (Fe3+ and Al3+) inhibited the particle-dispersion stability more strongly than the divalent ones (Ca2+ and Mg2+) and strongly inhibited the particle dispersion stability in pH ranges >10 and 4–10, respectively. Correlation analysis and calculations revealed that in a certain pH range, metallic ions in the pulp generated corresponding hydroxyl complexes or precipitates, which adsorbed on the mineral-particle surfaces, reduced the potential energy of interparticle interactions and enhanced the particle aggregation, thereby inhibiting the dispersion stability. [ABSTRACT FROM AUTHOR]

In order to extract pure cell populations from multiple cell populations or to extract the required components from complex samples, a novel regulation method of induced‑charge electro‑osmotic (ICEO) is proposed, based on the superposition effect of dual electric fields, to study the remodeling mechanism of the ICEO vortex and its particle control performance. Firstly, a multi‑physical coupling simulation model is established and the asymmetric evolution mechanism is studied. Secondly, the particle control device is designed and processed, and the particle control experimental system is built. Then, the aggregation and longitudinal migration characteristics of single particle induced by asymmetrically ICEO vortices at different voltages are studied. Finally, aggregation and separation characteristics of various particles within the asymmetric ICEO vortices are explored. The results show that this method can achieve the aggregation, migration and separation of micro‑scale particles in a simple control way, and it has great application potential in the field of environmental detection and disease diagnosis. [ABSTRACT FROM AUTHOR]

To design and operate various equipment of the solids control system in offshore drilling platforms, it is important to establish how the moisture content influences the characteristics of drilled cuttings to form packed beds and flow over solid surfaces. The current study comprehensively analyzes how moisture content, primarily composed of water and representing waterbased muds (WBMs), influences the bed packing properties and drilled cuttings' flowability. The particle aggregation/disaggregation dynamics, loose and tapped bulk densities and porosities, compaction dynamics of packed beds, Hausner ratio, and angle of repose of drilled cuttings with ten distinct moisture contents (1.4--44.0 wt%) were analyzed. It was noticed that the increment of moisture content up to 15.2% promoted the formation of looser interparticle structures. However, these structures were steadier, showing greater difficulty flowing and releasing air/liquid. The continuous increment of moisture content beyond 15.2% promoted a complete change in the material behavior. The interparticle structures became denser. The material could flow and release air/liquid more easily. In addition, it was possible to establish a classification of the different behaviors of drilled cuttings according to the moisture content. Predictive models were proposed to describe the influence of the moisture content on the bed packing and flowability properties of drilled cuttings. [ABSTRACT FROM AUTHOR]

A relative motion model was used to numerically simulate the phenomenon of particle aggregation in shear thinning fluids. To understand the shear thinning effects on particle mechanical properties in microfluidics, the shear thinning matching was performed with viscoelastic and non-viscoelastic fluids. The research results indicate that, shear thinning characteristics can significantly alter the mechanical properties of particles. In non-viscoelastic fluids, shear thinning can cause the aggregation position of particles to move towards the wall, and has an incentive effect on the aggregation speed of particles. In viscoelastic fluids, the occurrence of shear thinning will bring a decrease of the fluid elasticity, resulting in particle convergence from the center to the wall. [ABSTRACT FROM AUTHOR]

Abstract Electrodes with a maximal active site density are critical for high‐performance high‐temperature electrochemical cells (HTECs). One widely employed approach involves the use of porous nanostructures with a high surface‐to‐volume ratio. However, their active site densities inevitably decrease owing to particle aggregation induced at high temperatures, necessitating further development of electrode processing techniques. Taking Pt/yttria‐stabilized zirconia (YSZ) interface as a model system, a Pt nanostructured textile akin to the cantaloupe‐rind pattern with high mechanical integrity is fabricated. Application of an AC voltage to this textile electrode at an elevated temperature reduces the Pt particle size from submicron to 10–80 nm forming a nanocomposite with YSZ, accompanied by a 40‐fold increase in current density under high‐temperature water electrolysis conditions. Furthermore, the AC voltage application to a partially aggregated electrode restores its nano‐blended structure associated with the recovery of its activity. This technique is effective in counteracting particle aggregation on demand, providing an alternative approach to achieve high performance and extended lifetimes in HTECs.

Drug delivery systems have renewed attention in recent years to achieve targeted delivery while decreasing toxic side effects. However, there are many factors that prevent optimal administration of drug delivery particles. For instance, protein corona formation and aggregation both decrease the circulation half‐life of drug delivery particles, leading to sequestration to the liver and spleen. Therefore, optimal surface modifications are needed to decrease protein corona formation and avoid aggregation. In this work, polystyrene particles were modified with multi‐arm and linear polyethylene glycol (PEG) to determine their aggregation profiles and protein corona formation. Multi‐arm PEGs were found to aggregate more than linear PEGs, due to the change in zeta potential from unreacted end groups, which may lead to shorter circulation half‐lives. Furthermore, the protein corona formation and composition were studied after different washing procedures, highlighting the importance of studying protein corona formation with undiluted blood plasma. [ABSTRACT FROM AUTHOR]

The editorial in "Frontiers in Marine Science" explores the mechanisms and ecology of suspended-particle capture in marine systems, focusing on topics such as particle aggregation, filter feeding, and larval settlement. The research presented in the editorial covers a wide range of interdisciplinary studies, including the capture of particles by suspension-feeding marine animals, hydromechanics of feeding structures, and sediment deposition in marine vegetation canopies. The authors highlight the importance of understanding fluid dynamics, particle dynamics, and fluid-morphology interactions in predicting and advancing our knowledge of particle capture processes in marine environments. [Extracted from the article]

The present study dealt with the evaluation of the particulate aggregation in a suspension of multi-walled carbon nanotubes using fractal theory and rheological properties including thixotropy. The multi-walled carbon nanotubes are dispersed in Newtonian glycerol in the concentration range between 0.2 and 0.45 wt%. Rheological measurement was performed for the suspension at various dispersion times up to 300 min. The suspension showed thixotropy, shear-thinning behavior, and yield stress. It also exhibited plateaus of storage modulus in frequency and strain sweep tests. As the dispersion time increases, thixotropy, low-shear viscosities, and yield stress increase, and then their increasing rates slow down. Suspension's electrical conductivity also showed similar behavior as that of thixotropy with the dispersion time. Viscoelastic behavior was combined with a fractal concept to provide the fractal dimensions of the flocs in the suspension at various dispersion times. The fractal dimension tends to decrease with the dispersion time. Conclusively it is interpreted that as the dispersion proceeds flocs become smaller and chain-like, then the reduced and thinned flocs build the wider range of network structures at rest state. [ABSTRACT FROM AUTHOR]

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The design of continuous thickeners and clarifiers is commonly based on the solid flux theory. Batch sedimentation experiments conducted with solid concentrations still provide useful information for their application. The construction of models for the velocity of settling allows the estimation of the flux of solids throughout time, which can, in turn, be used to find the area of the units required to achieve a given solid concentration in the clarified stream. This paper addresses the numerical treatment of data obtained from batch sedimentation experiments of calcium carbonate particles. We propose a systematic framework to fit a model that is capable of representing the process features that involve (i) the numerical differentiation of data to generate initial estimates for the instantaneous velocity of settling; (ii) the integration of a differential equation to fit the model for the velocity of settling; and (iii) the assessment of the quality of the fit using common statistical indicators. The model used for demonstration has a theoretical basis combined with an empirical component to account for the effect of the particle concentrations and their state of aggregation. The values of the numerical parameters obtained are related to the characteristic dimensions of the aggregates and their mass-length fractal dimensions. [ABSTRACT FROM AUTHOR]

Designing a compact hydraulic pipe flocculator is a common challenge for various water purification and wastewater processes where space is limited. Various geometrical parameters are analysed to identify the most important parameters when designing an efficient system for a Reynolds number of Re D = 20, 000. A coupled CFD-PBE model is applied to a total of 123 geometrical configurations to simulate particle aggregation and breakage due to the local velocity gradients in the configurations. The shear present in the 90∘ pipe bends is the dominating factor in the final aggregate size and therefore the most important geometrical factor is the bend radius. Secondly, it is observed that the primary length, L 1 , has the second-largest impact as a linearly increasing particle diameter is observed along the straight pipe. Helically coiled geometrical configurations with no straight sections, L 1 = L 2 = 0, and a bend radius of r b ≥ 2 d h result in large particles as a constant but moderate cross-sectionally averaged turbulent energy dissipation is observed throughout the pipe. The largest volume-averaged particle size is observed for a configuration with a primary length of L 1 = 20 d h , a secondary length of L 2 = 0 and a bend radius of r b = 2.5 d h. • Linearly increasing particle aggregation during straight sections. • Bend radius is the single-most important geometrical parameter. • Helically coiled configurations shows promising results. • The largest aggregates are obtained with L 2 = 20 d h , L 2 = 0 and r B = 2.5 d h. [ABSTRACT FROM AUTHOR]

Introduction: Understanding organic amendment and the agglomeration of bauxite residue particles is vital to soil amelioration of bauxite residues. In this study, a pot culture experiment was conducted to illustrate the aggregation of organic amendment on bauxite residues particles and its improvement mechanism. The single organic amendment and its combination with soil inoculum were conducted to explore the aggregation effect of organic matter on bauxite residue particles, and its correlations with microbial rehabilitation.Methods: The dry- and wet-sieving method were used to obtain different sizes of aggregates. The concentrations of soil organic carbon and iron and aluminum (Fe/Al) oxides in the forms extractable by DCB (Fed/Ald) and oxalate (Fe0/Al0) were measured. Microbial rehabilitation after 180 days incubation was determined with the methods of Biolog Ecoplate™ and the high-throughput sequencing.Results and Discussion: The results showed that over 180 days incubation, the alkalinity of bauxite residues was significantly decreased with the organic amendment based on the value of pH, EC and ESP (down to 9.26, 0.61 m/cm and 55.5%, respectively, in HS3). Secondly, organic amendment significantly promoted microbial community establishment and ecological function recovery. Moreover, the MWD value of aggregates also increased to 0.73 mm from the initial 0.32 mm, companied with the increase of the Fe/Al oxidizes. The further Pearson relationship analysis and the characterization of EPMA and SEM indicated that the organic matter and Fe/Al oxides played important roles in cementing fine bauxite residues particles and increasing aggregates stability, while this aggregation process was accelerated by the establishment of microbial ecology in bauxite residues. Therefore, organic amendment was more implication in soil amelioration of bauxite residues other than the directive modifications on alkalinity.

Silver nanoparticles (AgNPs) are obtained herein by green synthesis using plant extracts instead of chemical reagents. However, the AgNPs fabricated via green synthesis are prone to aggregation, and their reproducible formations are difficult owing to the lack of capping ability in the extract. Although such aggregations of AgNPs are also observed in chemical synthesis, the phenomenon is more severe in green synthesis. In this study, we used Pinus koraiensis pinecone extract as a new green-synthetic agent along with 1 mM AgNO 3 and diatomite (DE) as the biosilica surface to prepare AgNPs stably. Scanning electron microscopy with energy-dispersive X-ray spectroscopy analysis confirmed that the AgNPs were formed on DE by green synthesis with a size of 27 nm; they were non-aggregated and well-dispersed on the DE surface. The AgNP-coated DE composite (AgNPs/DE) showed antibacterial activity that could kill > 99% of E. coli and S. aureus within one hour. Further, the AgNPs/DE with antimicrobial activity can be used up to five times repeatedly. The use of DE in the green synthesis of nanoparticles can thus provide advantages such as adequate dispersion and enhanced ability of the AgNPs. The results obtained herein support the environmentally friendly strategy of preparation and application of AgNPs. [Display omitted] • Green synthesis of silica nanoparticle (AgNPs) by pinecone extract was done on diatomite (DE) to yield DE/AgNPs. • In AgNPs/DE composite, the formed AgNPs are well dispersed on diatomite surface. • AgNPs/DE composite showed good antibacterial activity for gram-positive and gram–negative bacteria. • Antibacterial activity of AgNP can be re-used via AgNPs/DE composite. [ABSTRACT FROM AUTHOR]

Discoveries made during the 18 May 1980 eruption of Mount St. Helens advanced our understanding of tephra transport and deposition in fundamental ways. The eruption enabled detailed, quantitative observations of downwind cloud movement and particle sedimentation, along with the dynamics of co-pyroclastic-density current (PDC) clouds lofted from ground-hugging currents. The deposit was mapped and sampled over more than 150,000 km2 within days of the event and remains among the most thoroughly documented tephra deposits in the world. Abundant observations were made possible by the large size of the eruption, its occurrence in good weather during daylight hours, cloud movement over a large, populated continent, and the availability of images from recently deployed satellites. These observations underpinned new, quantitative models for the rise and growth of volcanic plumes, the importance of umbrella clouds in dispersing ash, and the roles of particle aggregation and gravitational instabilities in removing ash from the atmosphere. Exceptional detail in the eruption chronology and deposit characterization helped identify the eruptive phases contributing to deposition in different sectors of the distal deposit. The eruption was the first to significantly impact civil aviation, leading to the earliest documented case of in-flight engine damage. Continued eruptive activity in 1980 also motivated pioneering use of meteorological models to forecast ash-cloud movement. In this paper, we consider the most important discoveries and how they changed the science of tephra transport. [ABSTRACT FROM AUTHOR]

Purpose: Arterial shear forces may promote the embolization of clotted blood from the surface of thrombi, displacing particles that may occlude vasculature, with increased risk of physiological complications and mortality. Thromboemboli may also collide in vivo to form metastable aggregates that increase vessel occlusion likelihood. Methods: A micromechanical force (MMF) apparatus was modified for aqueous applications to study clot-liquid interfacial phenomena between clotted porcine blood particles suspended in modified continuous phases. The MMF measurement is based on visual observation of particle-particle separation, where Hooke's Law is applied to calculate separation force. This technique has previously been deployed to study solid–fluid interfacial phenomena in oil and gas pipelines, providing fundamental insight to cohesive and adhesive properties between solids in multiphase flow systems. Results: This manuscript introduces distributed inter-particle separation force properties as a function of governing physio-chemical parameters; pre-load (contact) force, contact time, and bulk phase chemical modification. In each experimental campaign, the hysteresis and distributed force properties were analysed, to derive insight as to the governing mechanism of cohesion between particles. Porcine serum, porcine albumin and pharmaceutical agents (alteplase, tranexamic acid and hydrolysed aspirin) reduced the measurement by an order of magnitude from the baseline measurement—the apparatus provides a platform to study how surface-active chemistries impact the solid–fluid interface. Conclusion: These results provide new insight to potential mechanisms of macroscopic thromboembolic aggregation via particles cohering in the vascular system—data that can be directly applied to computational simulations to predict particle fate, better informing the mechanistic developments of embolic occlusion. [ABSTRACT FROM AUTHOR]

Natural manganese (Mn) oxide coatings, resulting from the heterogeneous nucleation on foreign substances, have garnered interest based on their importance in the reaction with organic substances and in environmental systems. However, the heterogeneous nucleation of the natural Mn oxide coatings still remains elusive. Here, via fast photochemical oxidation of Mn 2+ (aq), we show that Mn(IV) oxide nuclei form and aggregate on quartz in three distinct successive stages: (i) a nanocrystalline film of unaligned grain forms, (ii) nanoislands develop on the film, and (iii) nanorods form on the nanoislands. Each stage has different crystalline structures and forms by aligned attachment of nanoscale precursors on the preceding surface. Crystal lattice analyses confirm the crystalline development, from the short-range order of the Mn oxide film to the long-range order of the nanorods. Also, the heterogeneous nucleation observed in this work produced groutellite-like tunnel structures of Mn oxide on quartz. This revealed pathway of the heterogeneous nucleation can offer a new perspective on the variety of poorly crystalline structures of natural Mn oxides found in the environment, which can affect elemental redox cycles, contaminant sequestration and removal, and soil carbon storage.

Drug therapy for vascular disease has been promoted to inhibit angiogenesis in atherosclerotic plaques and prevent restenosis following surgical intervention. This paper investigates the arterial depositions and distribution of PEG-functionalized magnetic nanocomposite clusters (PEG_MNCs) following local delivery in a stented artery model in a uniform magnetic field produced by a regionally positioned external permanent magnet; also, the PEG_MNCs aggregation or chain formation in and around the implanted stent. The central concept is to employ one external permanent magnet system, which produces enough magnetic field to magnetize and guide the magnetic nanoclusters in the stented artery region. At room temperature (25 °C), optical microscopy of the suspension model's aggregation process was carried out in the external magnetic field. According to the optical microscopy pictures, the PEG_MNC particles form long linear aggregates due to dipolar magnetic interactions when there is an external magnetic field. During magnetic particle targeting, 20 mL of the model suspensions are injected (at a constant flow rate of 39.6 mL/min for the period of 30 s) by the syringe pump in the mean flow (flow velocity is Um = 0.25 m/s, corresponding to the Reynolds number of Re = 232) into the stented artery model. The PEG_MNC clusters are attracted by the magnetic forces (generated by the permanent external magnet) and captured around the stent struts and the bottom artery wall before and inside the implanted stent. The colloidal interaction among the MNC clusters was investigated by calculating the electrostatic repulsion, van der Waals and magnetic dipole-dipole energies. The current work offers essential details about PEG_MNCs aggregation and chain structure development in the presence of an external magnetic field and the process underlying this structure formation. [ABSTRACT FROM AUTHOR]

The stabilization of soil organic matter is crucial for global carbon cycling processes as soil stores large amounts of organic carbon. The occlusion of SOM within minerals sequesters these organic molecules, rendering them inaccessible to interference from biotic and abiotic factors. However, the microscopic mechanisms of occlusion are lacking. In the past few years, many researchers have focused on the elucidation of the occlusion process, and the results are summarized in this review. The occlusion of representative SOM such as natural extracted or commercial humic substances, sugars, amino acids within minerals including calcite, clay, metal oxides, were observed by various in situ and ex situ methods, such as atomic force microscopy, nano-scale secondary ion mass spectrometry and synchrotron-based infrared micro spectroscopy. These results have shown that minerals can occlude SOM either via organo-mineral aggregation or within growing hillocks, which are classical growth features on crystal surfaces, and the microscopic mechanisms have been illustrated in this review. The occlusion process is influenced by various factors, including the characteristics of minerals and the composition of SOM and soil solution conditions, which are mediated by the interactions of organo-mineral interfaces. Finally, some new perspectives for future research of occlusion are provided in order to give new possibilities for observing and comparing the detailed occlusion process in soils from different areas. In summary, SOM can be retained, protected and stabilized by soil minerals via occlusion either by aggregation or within growth hillocks, influenced by various factors. The results have implications for global carbon cycling in soil ecological systems. Soil organic matter could be occluded within soil minerals via aggregation and hillocks. [ABSTRACT FROM AUTHOR]

• There are three different flow patterns in the top ash ring. • The intensity of longitudinal circulation affects critical mass of top ash ring. • Satisfactory flow regime of top ash ring was obtained with different particles. In this work, the experiments were conducted to study on the instability characteristics of top ash ring in the annular space using a ø160mm cyclone with various particles at inlet velocities V in = 12 ∼ 20 m/s and inlet concentrations C in = 10 ∼ 100 g/m3. A high-speed camera was used to take images for investigating the flow patterns of the top ash ring. The experimental results show the top ash ring exhibits strong instability characteristics, there are three different flow patterns in the top ash ring. The longitudinal circulation in the annular space was analyzed to explain the formation and shedding mechanisms of the top ash ring. A force balance analysis on a single particle is conducted to establish the stability criteria for the single particle. The mass balance of the top ash ring is analyzed to determine the flow patterns for top ash ring. Finally, the flow regime of the top ash ring is modeled with Froude Fr and relaxation time τ , which is agreement with experimental results. [ABSTRACT FROM AUTHOR]

[Display omitted] • The slippery organogel (SOG) surface was rapidly fabricated using a photo-induced process. • The SOG surface effectively aggregated biological droplets containing organic particles. • Particles aggregated into a confined area can improve detection sensitivity and reproducibility. The drying of droplets containing non-volatile solutes presents significant potential for sensing applications, including disease diagnosis, and the detection of harmful substances. Colloidal droplets form various patterns on surfaces after evaporation, and controlling the deposited patterns to achieve the desired characteristics is crucial in sensing applications. In this study, we propose a novel approach that employs a slippery organogel (SOG) surface that can be rapidly fabricated based on a photo-induced process to enhance the sensitivity and reproducibility during detection. The SOG forms a thin lubricating layer on the surface, which reduces the pinning of the three-phase contact line, causing the aggregation of particles within a confined area. To analyze the aggregation characteristics of colloidal droplets on the SOG, we compared the deposited particles after evaporating four types of colloidal droplets on the following different surfaces: hydrophilic, hydrophobic, organogel (OG), and SOG. The SOG surface demonstrated a superior particle aggregation capability across various colloidal droplets, which is crucial for the future development of high-sensitivity detection technologies. [ABSTRACT FROM AUTHOR]

The conventional synthesis of cerium oxide nanoparticles (CeNPs) relies on the use of trivalent cerium and an oxidizer to ensure a thorough hydrolysis. This study explores CeNPs formation via the hydrolysis of tetravalent cerium, specifically through the spontaneous reaction of ceric ammonium nitrate (Ce(NH 4) 2 (NO 3) 6) under varied aging conditions, including adjustments in pH, concentration, and heating strategy. This research adopts a thermo-hydrolysis method to synthesize CeNPs with small primary particles (2–3 nm) to loose dendritic clusters (5–8 nm). Additionally, when the starting pH of the solution decreases below 0.8, it favors the formation of clusters with larger diameters (15–20 nm). Analyses using dynamic light scattering (DLS), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) indicate that CeNPs particle size in acidic environments is predominantly determined by the extent of primary particle aggregation, influenced by nitrate adsorption. Overall, our comprehensive analysis of the CeNPs evolution provides fundamental insights for the development of a size/structure controllable synthetic strategy for nanoparticle manufacturing. [Display omitted] [ABSTRACT FROM AUTHOR]

• The microscopic formation morphology of hydrate particles under wax-containing conditions. • The effects of wax content and wax composition on the kinetic characteristics of hydrate formation. • The effect of wax on hydrate aggregation was investigated by combining torque and particle size. • The effect of wax content and wax composition on the aggregation particle size of hydrate particles. • The influence mechanism of wax on the aggregation process of hydrate particles is proposed. In recent years, the formation and aggregation of wax and hydrate under the condition of coexistence has become a hot spot in the safety assurance of deep-water pipeline flow. In order to clarify the influence mechanism of wax and hydrate in deep-sea crude oil under coexistence conditions, the effects of different wax-containing conditions on the nucleation, growth and aggregation characteristics of hydrate in oil–water emulsion were studied by macroscopic and microscopic experimental equipment. The results show that low wax content (0–3.wt%) provides nucleation sites for hydrate formation and thus promotes hydrate formation. High wax content (>3.wt%) inhibits hydrate formation by preventing water droplets from contacting gas molecules. Low wax content (0–3.wt%) significantly reduces hydrate interparticle aggregation. High wax content (>3.wt%) promotes hydrate interparticle aggregation, which changes the flow characteristics of the hydrate slurry. In addition, through further analysis by PVM and high-speed camera, a wax-containing hydrate aggregation mechanism model was established. [ABSTRACT FROM AUTHOR]

Selective aggregation can be used to improve the collection of fine valuable mineral particles often lost in industrial separation processes. This approach might be applicable to flocculate fine copper mineral particles such as chalcopyrite. It is hypothesised that the polymeric flocculant charge type will influence selectivity between chalcopyrite and waste minerals. This work investigates the use of charged anionic (APAM) and cationic (CPAM) polyacrylamides to selectively aggregate negatively charged chalcopyrite from its common waste (quartz). The interaction of the polymers with the mineral's surfaces as well as its flocculation capability were investigated through adsorption isotherms, turbidity tests, and in-situ aggregate size measurement. Furthermore, the ability to selectively aggregate and recover the valuable chalcopyrite from a quartz mixture by sedimentation was assessed. The results indicated that both charged polymers can be used to aggregate fine chalcopyrite particles, however, CPAM is non-selective towards the valuable mineral, as it also aggregates quartz. CPAM has a stronger affinity for both minerals, probably due to charge-charge interaction adsorption mechanisms, whereas APAM adsorption was lower, and more likely to be driven by hydrogen bonding. The interaction of APAM with quartz was limited probably because its highly negatively charged surface tends to repel the anionic polymer. Finally, the recovery of the chalcopyrite by sedimentation separation improved when using both polymers, but higher recoveries were obtained when using APAM. [Display omitted] • Fine CuFeS 2 particles were aggregated using anionic and cationic polyacrylamides. • Only APAM is selective towards CuFeS 2 , while CPAM also flocculates quartz. • Polymer charge affects the adsorption mechanism and affinity to both minerals. • Aggregate size and structure were studied with a novel image analysis technique. • Recovery of CuFeS 2 by sedimentation separation was improved with polymer addition. [ABSTRACT FROM AUTHOR]

Nickel-based materials are promising electrocatalysts for anodic oxidation of 5-hydroxymethylfurfural (HMF) to value-added 2, 5-furandicarboxylic acid (FDCA). However, their catalytic efficiency is impeded by the sluggish phase transformation of Ni(II) hydroxide to the active Ni(III) oxyhydroxide. Herein, we demonstrate for the first time that the phase transformation kinetics and the HMF oxidation activity of nickel nanoparticles can be modulated by creating self-assemblies with different particle aggregation structures: ordered nanoarrays, disordered nanoarrays, and random aggregates. Notably, the nanoparticle assembly featuring an ordered nanoarray structure exhibits the highest activity, achieving 99.8 % HMF conversion and 99.2 % FDCA yield at 1.36 V. In situ Raman spectroscopy and electrochemical analysis reveal that the ordered nanoarray effectively accelerates the transformation kinetics, attributed to the reduced dehydrogenation barrier of Ni(II) hydroxide as confirmed by density functional theory calculations. This work contributes new insights into the structure-performance relationship of Ni-based catalysts, offering valuable guidance for designing high-performing electrocatalysts. [Display omitted] • Ni nanoparticles with different aggregation structures were successfully constructed. • Particle aggregation structure impacts HMF oxidation on Ni nanoparticles. • Tailored Ni nanoparticles assembly exhibits excellent HMF oxidation performance. • Ordered nanoarrays of Ni promotes the transformation of Ni(II) to Ni(III). • Larger catalyst-electrolyte interfaces reduce dehydrogenation barrier of Ni(OH) 2. [ABSTRACT FROM AUTHOR]

The pore structure of aeolian deposits is essential for predicting their mechanical properties and the climatic conditions during their deposition. The discrete element method (DEM) is a practical approach for analysing the formation and evolution mechanisms of aeolian deposits' pore structure. However, the effect of particle shape and non-contact van der Waals force on deposits' pore structure with different particle sizes needs further exploration to enhance the efficiency and accuracy of DEM simulations. We developed a VdwForce model for DEM that accounts for the van der Waals force's long-tail effect, and we conducted loess air-fall numerical tests that matched laboratory simulation tests. DEM simulations and laboratory tests show that the deposits' porosity increased as the median particle size decreased, whether using spherical or actual shape particles in simulations. When deposits formed by particles with actual shapes have dense packing structures, simulations utilising spherical particles of the same size produce larger porosities. The primary reason of the alteration in the pore structure of the loess air-fall deposits is the shift in the quantity and pattern of particle agglomerates caused by van der Waals attractive force. So, the aggregation process during air-fall was essential for forming overhead pore structures. [ABSTRACT FROM AUTHOR]

Particles will aggregate in the presence of dense mist in the wet electrostatic precipitator (WESP), and larger size particles with changed distribution make discharge more significant. This article puts forward the simulation of corona discharge with the existence of particle aggregation effect, which shows the characteristics of electron density distribution during the propagation. Besides, we also provide propagation patterns of branching and quenching phenomenon of plasma channels in the presence of particle aggregation. The results indicate that particle aggregation will considerably influence the plasma patterns. When the electron avalanche reaches the particle distributing areas, there will be several plasma channels formed and a narrow diffusion radius around the aggregated particles. When particles gather around the electrode, which means dense particle distribution, corona quenching happens with dense particle distribution. [ABSTRACT FROM AUTHOR]

In order to fabricate electrically and mechanically reinforced biopolymer-based composites, we control the dispersion of the particles through the addition of a secondary polymer with high affinity to carbon black (CB) particles. The addition of a small amount of the secondary polymer induces the aggregation of CB particles beyond interfacial localization in a ternary composite. The aggregation and percolation network in poly(lactic acid) (PLA)-based ternary systems are investigated through a scaling analysis. According to rheological and geometric fractal analyses, the secondary polymer induces an aggregation of CB particles to form a percolation network because the induced-diffusion effect is stronger than the interaction between the particles, leading to a particle aggregate with a high-order structure. The modulus (G 0 ′ ) of the CB/PLA binary composite has a scaling relationship with the particle volume fraction (φ), G 0 ′ ∼ φ 1.92 (φ c , G ′ = 2.2 %). In the CB/PLA binary composite, the addition of a small amount of secondary polymer having strong chemical affinity to CB changes the scaling relationship significantly depending on the type of the secondary polymer (G 0 ′ ∼ φ 2.17 ∼ 2.53 ) with a lower percolation threshold (φ c , G ′ ) (φ c , G ′ = 0.96 %). It also enhances the electrical percolation (electrical conductivity, σ d c ∼ φ 3.23 ∼ 3.78 φ c , σ = 1.50 % − 1.86 % for ternary composites) with an increase in the exponent and a lower percolation threshold (φ c , σ ). The secondary polymer serves as a binder and causes the aggregates to be well dispersed, leading to a brittle-ductile transition and significant enhancement of the ductility. [ABSTRACT FROM AUTHOR]

Abstract The rational design of drug delivery systems has led to enhanced targeting, increased efficiency, and a reduction of side effects in chemotherapies and vaccines. As most biological reactions took place at the interface, particle‐stabilized emulsion (Pickering emulsion), may offer major implications for the advanced drug loading, delivery, and controlled release. In fact, it is the aggregating particles that determined the multi‐level structure, multi‐valent cellular interactions, and the multi‐functional physiochemical properties in drug delivery. A deeper understanding on the tunable aggregating patterns and properties, as well as the underlying mechanisms, may pave the way for the efficient drug delivery, and also aided the progressing of “Aggregology” beyond molecules to particles, emulsions, and the biomedical applications. Here, the recent development of Pickering emulsions and their applications in drug delivery were thoroughly reviewed. Strategies to control over the physiochemical properties were illustrated based on particle properties, energy input, and the choices of continuous and dispersion phases. In particular, enough emphasis was attached on the structure‐effect relationship between the tunable physiochemical properties and the delivery process, such as the multi‐level structure for effective loading, flexibility and permeability for enhanced delivery, and the stimuli‐responsiveness for the controlled release. By channeling the unique interfacial properties and the enhanced drug delivery efficiency, this work may shed light on the rational design of Pickering emulsions for the efficient drug delivery.

On-demand switch on/off blood clogging is of paramount importance for the survival of mammals, for example as a quick response to seal damage wounds to minimize their bleeding rate. This mechanism is a complex chain process from initiated red blood cell aggregation at the target location (open wound) that quickly seals on a macroscopic scale the damaged flash. Inspired by nature an on-demand switchable particle clogging mechanism is developed with high spatial resolution down to micrometer size using light as an external non-invasive stimulation. Particle clogging can be adjusted on demand strong enough to even withstand pressure-driven fluid flow, additionally building up walls of aggregated particles, which stop the momentum of big particles under shear. The principle relies on a photosensitive surfactant, which induces under light illumination a long-ranged lateral attractive phoretic-osmotic activity of silica microparticles forcing them to aggregate. The strength of aggregation and therefore motion reduction or even stop of the particles against the fluid flow depends on the ratio between the aggregation strength and the velocity of the particles. The aggregation strength can be precisely controlled by the applied light intensity and adjusted particle concentration. Increasing both parameters results in a stronger aggregation tendency., (© 2024 The Authors. Small published by Wiley‐VCH GmbH.)

The reverse anionic flotation is commonly used to upgrade the mid-low grade phosphate ore in China. The mineral characterization of raw ore shows that carbonate and phosphate minerals combined with fine intergrowth, difficulty in upgrading. Flotation using nanobubbles (NBs) can significantly enhance the flotation efficiency of fine particles of minerals. To research the effect of NBs on the flotation process of this phosphate ore, two flotation tests with and without NBs were compared. The results show that the MgO removal had an increment of 10% in the case of NBs flotation versus conventional flotation in the approximate grade and recovery of P2O5. The foam product of NBs flotation had smaller dimensions than the conventional flotation. NBs enhanced the contact angle on dolomite surface from 45.8 ° to 64.5 °, and increases the d50 of dolomite from 20.49 μm to 30.43 μm. [ABSTRACT FROM AUTHOR]

The lubrication effectiveness of MoS2 nanoparticles as an oil additive remains unclear, restricting its application in industry to reduce friction. The goal of this work was to explore the lubrication mechanism of MoS2 nanoparticles as an oil additive. In this study, the oil film thickness behaviors of MoS2 nanoparticles in poly-alpha olefin (PAO4) base oil, PAO4 with 3 wt% dispersant (polyisobutyleneamine succinimide, PIBS), and 0W20 engine oil were investigated using an elastohydrodynamic lubrication (EHL) testing machine. Following the EHL tests, the flow patterns around the contact area and the tribofilm covering rate on contact area were studied using optical microscopy to understand the lubrication mechanism. The results indicate that both the dispersant and nanoparticle aggregation significantly affected the oil film thickness. The expected oil film thickness increase in the case of 0.1 wt% MoS2 in PAO4 base oil was obtained, with an increase from 30 to 60 nm over 15 min at a velocity of 50 mm/s. Flow pattern analysis revealed the formation of particle aggregation on the rolling path when lubricated with 0.1 wt% MoS2, which is associated with a tribofilm coverage rate of 41.5% on the contact area. However, an oil film thickness increase and particle aggregation were not observed during the tests with 0.1 wt% MoS2 blended with 3 wt% PIBS as the dispersant in PAO4 base oil, and for 0.75 wt% MoS2 in 0W20 engine oil. The results suggest that nanoparticles responsible for tribofilm formation originated from aggregates, but not the well-dispersed nanoparticles in point contact. This understanding should aid the advancement of novel lubricant additive design. [ABSTRACT FROM AUTHOR]

Particle size distribution (PSD) in the ocean is a fundamental property that influences carbon export and food webs; however, PSD variation and its causes in oligotrophic oceans are not entirely clear. Here, we used Laser In-Situ Scattering and Transmissometry to investigate PSD (size range 5.2–119 μm) and related variables at 11 stations in the surface layer (0–20 m) of the Kuroshio region of the western North Pacific, where strong current causes dynamic hydrographic and ecological conditions. PSD slopes (range –3.2 to –4.2), derived from the power law model, were steeper at onshore stations and flatter at oligotrophic stations located offshore and at lower latitudes. Notably, slopes tended to become steeper with increasing chlorophyll a concentration, opposing the generally observed relationship between the two variables, whereas they became flatter with increasing transparent exopolymer particle (TEP) concentration. Possible explanations of the above results are localized occurrence of nanophytoplankton and TEP facilitation of particle aggregation. The results support the hypothesis that PSD slopes are controlled by a multitude of factors, including phytoplankton community dynamics and aggregation processes. To determine whether TEP-induced particle aggregation enhances or suppresses carbon export, we need a better understanding of the nature (porosity, density, and sinking velocity) of aggregates in oligotrophic oceans.

[Display omitted] Combination of microwave irradiation (MWI) and ionic liquids (IL) is widely used for the synthesis of nanoparticles (NP) via decarbonylation of zero-valent metal carbonyl precursors. However, we carefully raise a question as to whether this combination is always beneficial. Upon MWI, highly-absorbing materials such as ILs would be subject to local intense heating, likely resulting in the occurrence of localized chemical decomposition. The decomposition is expected to influence the growth mechanism of NPs due to changes in the electrostatic and steric effects. If the assumption is valid, it should be possible to decompose IL and destabilize the NPs by modifying the amplitude of the incident microwaves. In other words, it should also be possible to control the particle aggregation by circumventing the decomposition of the IL. A series of comparative studies were conducted using a model system (i.e. [BMIm][BF 4 and Ru 3 (CO) 12). Variables were systematically controlled. After MWI, the decrease in colloidal stability of NPs was identified. In the formation of Ru NPs via decarbonylation, the association between incident microwave intensity, chemical decomposition of IL, and initiation of particle aggregation has been demonstrated. Conditions that can accelerate or alleviate the decomposition and the aggregation are also corroborated. [ABSTRACT FROM AUTHOR]

Filtration of biopharmaceutical streams can be complex due to the variety of components in the stream and their interactions among themselves and with the filter pore surfaces. This work used a variety of measurements to study the filtration of model silica nanoparticles through asymmetric hydrophilized polyethersulfone (mPES) membrane in solutions covering a range of pH and ionic strengths. Measurements included particle size, particle concentration, zeta potential, particle-particle and particle-membrane surface intermolecular forces. These measurements were used to rationalize observed particle capture behavior under various filtration conditions. We found that increasing ionic strength and decreasing pH resulted in higher particle aggregation and higher particle retention due to adsorption of model silica nanoparticles to the membrane and sieving of aggregates within the membrane. In addition, captured particles can be eluted from the membrane in some cases, depending on the operating conditions, extent of particle loading, buffer flush pressure, and buffer pH and conductivity conditions. These findings provide insight into methods to improve filtration performance and particle capture or release, including product recovery, in filtration processes. [Display omitted] • Using fundamental measurements to guide the selection of filtration conditions for maximizing particle recovery. • Correlated particle capture with particle aggregation and membrane – particle interactions. • PH, ionic strength, and operating pressure determine particle capture mechanism (adsorptive or size-based capture). [ABSTRACT FROM AUTHOR]

Fossil-made polymers harbor unique bacterial assemblages, and concerns have been raised that ingested microplastic may affect the consumer gut microbiota and spread pathogens in animal populations. We hypothesized that in an ecotoxicity assay with a mixture of polystyrene (PS) and clay: (1) microbiome of the test animals inoculates the system with bacteria; (2) relative contribution of PS and the total amount of suspended solids (SS) select for specific bacterial communities; and (3) particle aggregation is affected by biofilm community composition, with concomitant effects on the animal survival. Mixtures of PS and clay at different concentrations of SS (10, 100, and 1000 mg/L) with a varying microplastics contribution (%PS; 0–80%) were incubated with Daphnia magna , whose microbiome served as an inoculum for the biofilms during the exposure. After 4-days of exposure, we examined the biofilm communities by 16S rRNA gene sequencing, particle size distribution, and animal survival. The biofilm communities were significantly different from the Daphnia microbiota used to inoculate the system, with an overrepresentation of predatory, rare, and potentially pathogenic taxa in the biofilms. The biofilm diversity was stimulated by %PS and decreased by predatory bacteria. Particle aggregate size and the biofilm composition were the primary drivers of animal survival, with small particles and predatory bacteria associated with a higher death rate. Thus, in effect studies with solid waste materials, ecological interactions in the biofilm can affect particle aggregation and support potentially harmful microorganisms with concomitant effects on the test animals. [ABSTRACT FROM AUTHOR]

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A successful drug delivery system must overcome complex biological barriers. For particles injected into the blood, one of the first and most critical barriers pertains to blood stability to circulate through the human body. To effectively design drug delivery vehicles, interactions between the particles and blood, as well as the aggregation behavior, must be understood. This work presents a method to analyze particle size and aggregation in blood plasma using a commercially available nanoparticle tracking analysis (NTA) system. As a model system, fluorescently labeled polystyrene nanoparticles are incubated in goat blood plasma and analyzed using NTA. The particles incubated in plasma are found to have a protein corona that is larger than what has been observed by dynamic light scattering (DLS) in diluted plasma. Particles that are decorated with a PEG layer are also found to have large protein coronas in undiluted plasma. Because NTA is based on a unique visualization method, large multicomponent aggregates could be observed and quantified in a manner not feasible with other techniques. PEGylation of the particles is found to decrease the multicomponent aggregation from 1000 ± 200 particles for unmodified to 200 ± 30 particles for 1K PEGylated per 1 × 105 total particles. [ABSTRACT FROM AUTHOR]

Featured Application: The investigated composed particles are of interest for future applications for nanoparticle-based surface-enhanced Raman scattering (SERS) analytics and as components in plasmonic sensing, such as biomolecules. The presence of the polycationic macromolecule poly(diallyldimethylammonium chloride) (poly-DADMAC) has a strong effect on the shape and size of colloidal gold nanoparticles formed by the reduction of tetrachloroauric acid with ascorbic acid in aqueous solution. It slows down nanoparticle growth and supports the formation of nonspherical, partially highly fractal and hierarchical nanoparticle shapes. Four structural levels have been recognized from the near-spherical gold nanoparticles in the lower nanometer range over compact aggregates in the midnanometer range and flower and star-like particles in the submicron range up to larger filamentous aggregates. High-contrast scanning electron microscope (SEM) images show that single gold nanoparticles and clusters of them are connected by bundles of macromolecules in large aggregates. The investigation showed that a large spectrum of different nanoparticle shapes and sizes can be accessed by tuning the poly-DADMAC concentrations and their ratio to other reactants. The nanoassemblies with a very high specific surface area might be of interest for SERS and heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

The net primary productivity (NPP) of marine phytoplankton is ∼50 Pg C year–1, and roughly 10–20% of this NPP is exported out of the surface ocean as sinking particulate organic carbon (POC). Numerous mechanisms are hypothesized to control POC export out of the surface ocean but the relative importance of the various mechanisms remains poorly quantified on global scales. Here, we use a previously published satellite-based mechanistic model of POC export to examine the effects on global POC export of size-specific physical aggregation, size-specific and temperature-dependent zooplankton fecal pellet production, and size-specific and temperature-dependent non-grazing phytoplankton mortality. We test these mechanisms in different model configurations to determine if these processes improve the ability of the model to match POC export observations, and to assess the role of each process in controlling global POC export. We find that all model configurations predict that over 60% of the global POC export is from small zooplankton fecal pellets. All model configurations predict similar total POC export, and we find only small differences in the magnitude, timing, and geographical variations of total POC export. However, the fraction of total POC export due to sinking phytoplankton aggregates, and that due to the fecal pellets of large zooplankton, vary by more than a factor of two across the different model configurations. The POC export in all models is most sensitive to parameters controlling zooplankton fecal fluxes and non-grazing phytoplankton mortality. We compared zooplankton grazing rates predicted by the models to results of experimental data, and found that some models match the experimental grazing rates better than others, although data uncertainties remain large. More field measurements of bulk ecosystem rates (i.e., phytoplankton aggregation and zooplankton grazing), as well as explicit determinations of of the proportion of fecal matter to phytoplankton aggregation, will help to better constrain mechanistic models of global POC export.

Laser induced Marangoni convection can be used to accumulate micro-particles. In this paper, a method is developed to control and accumulate the light absorbing particles dispersed in a thin solution layer. The particles are irradiated by a focused laser beam. Due to the photothermal effect of the particles, the laser heating generates a thermal gradient and induces a convective flow around the laser's heating center. The convective flow drives the particles to accumulate and form a particle aggregate close to the laser's heating center. The motion of particles is dominated by the Marangoni convection. When the laser power is high, the vapor bubbles generated by laser heating on particles strengthen the convection, which accelerates the particles' aggregation. [ABSTRACT FROM AUTHOR]

The freezing method used to prepare DNA-modified gold nanoparticles (SNA) has the advantages of being fast and simple, but the prepared SNA is easy to aggregate. In this paper, the effects of polyethylene glycol (PEG) as an organic macromolecular crowding agent on the single-strand polyadenylate DNA functionalized gold nanoparticles (polyA-SNA) and the single-strand thiolated DNA functionalized gold nanoparticles (HS-SNA) were systematically studied. The experimental results showed the molecular weight and concentration of PEG significantly affect the dispersion and DNA loading of the two kinds of SNA. An increase in DNA strand length inhibits the adsorption of thiolated DNA and polyA-DNA, and the hydrated particle size of SNA increases at first and then decreases with the length of the DNA strand. These phenomena lay on the speculative principle that PEG improved the energy barrier for gold nanoparticles (AuNPs) aggregation through the long chain of macromolecules, and the modification mode and length of surface DNA also play an auxiliary role. This work provided a systematic study and helpful results on improving the stability of SNA prepared by the freezing method. [Display omitted] [ABSTRACT FROM AUTHOR]

• Flotation tests were carried out using ultrasound without external aeration; • Particle aggregation and/or cavitation were observed; • Good separation of coal from quartz at coarse size fractions was achieved. This paper describes the flotation separation of naturally hydrophobic coal particles and hydrophilic quartz particles in water (free of any reagents) using ultrasound-induced bubbles only, without any additional air supply. A laboratory-scale flow tubing system with an ultrasound transducer was designed and used. The experiments were conducted for coking coal, quartz and their mixture, respectively, over a broad range of particle size. Results showed that using ultrasound with a relatively high energy input, acoustic cavitation occurred in water and on the surface of coal particles, and different behaviours of coal particles and quartz particles under this condition were observed: coal particles formed larger aggregates and most of them were trapped in the slurry or floated to the surface of the slurry, while quartz particles had very slight aggregation and settled down. This difference enabled good separation of coal particles from quartz particles, with high combustible recoveries and product grade over a broad particle size range tested (including 250–500 µm for coal particles). When the energy input of ultrasound was relatively low, however, no cavitation bubbles were visible, with slight aggregation and trapping of coal and quartz being observed and explained by the acoustic radiation force. [ABSTRACT FROM AUTHOR]