Cohesive Particles Research Articles

Activation of muscle amine functional groups using eutectic mixture to enhance tissue adhesiveness of injectable, conductive and therapeutic granular hydrogel for diabetic ulcer regeneration

Herein, Polydopamine-modified microgels and microgels incorporated with superficial epoxy groups were synthesized and applied as precursors for the fabrication of four granular hydrogels. To enhance the tissue adhesiveness, a ternary deep eutectic solvent was synthesized to activate the muscle amine functional groups facilitating the formation of robust NC bonds at ambient conditions. At a certain shear rate of 10 s−1, hydrogel DMG displayed a viscosity of 9×103 Pa/s, representing the highest complex viscosity among the tested hydrogels primarily driven by quinone groups in PDA which enhanced reversible interactions, thereby increasing particle cohesion. Moreover, the intersection point escalating from about 4×103 to approximately 9×104 as the concentration of DMG increased from 0 % (for MG) to 70% (7D3MG) by weight. There was a decrease in adhesion strength from 0.45 ± 0.08 N in MG to 0.39 ± 0.16 N, 0.35± 0.18 N, and 0.33 ± 0.15 N for 3D7MG, 7D3MG, and DMG respectively, suggesting that MG was capable of forming numerous covalent bonds, thereby enhancing its adhesion to the substrate. The type of eutectic mixture affected the electrical conductivity and a very important point was the changes in resistance value with time. For MG catalyzed by [DES]AZG, the resistance increased only by 1.3 % (from 3.37 to 3.81 kΩ) at day 3 and 37.09 % (from 3.37 to 4.62 kΩ) at day 5. The 3D7MG hydrogel exhibited superior therapeutic efficacy toward diabetic wound regeneration. The proliferation index value for 3D7MG-[DES]AZG and 3D7MG-[DES]AG were calculated 42.3 % and 58.6 %, respectively, while the control group exhibited a lower value of 37.8 %.

Divergent responses of aggregate breakdown by slaking to nitrogen forms in solution for contrasting soil types

Aggregate stability strongly affects many soil processes and is critical to maintain sustainable agriculture. Aggregate breakdown is controlled by the interaction between soil intrinsic properties and solution characteristics. Nitrogen fertilization including different forms is well known to influence aggregate stability; however, relative to their long-term effects, there is little recognition on the rapid response of aggregate breakdown to nitrogen solutions. This study aimed to examine the effects of nitrogen form and concentration on aggregate stability for different types of soils. Aggregate breakdown against slaking of three soil types (Phaeozem, Luvisol, and Acrisol) and three horizons (organo-mineral (A), illuvium (B), and parent material horizons (C)) was determined subjected to nitrogen solutions of three forms (CO(NH2)2, NH4+, NO3–) and five concentrations (0.05 ∼ 1.0 mol/L). Among nitrogen forms, urea solution almost had non-significant effect irrespective of soil type and horizon (p > 0.05); for NH4+ and NO3– solutions, aggregate stability showed little variations (MWD of 0.19 ∼ 0.26 mm) with electrolyte concentration for Phaeozem in B and C horizons, overall increased for Luvisol and Phaeozem in A horizon, and decreased first and then reached a steady state for Acrisol. The effects of nitrogen forms on aggregate breakdown were dependent on soil aggregation status or cementing agents (mainly organic matter, clay mineralogy). Electrolyte nitrogen solutions (NH4+ and NO3–) inhibited aggregate breakdown mainly through reducing electrostatic repulsive forces for moderately developed soils rich in swelling clays, and promoted aggregate breakdown by both weakening particle cohesion and enhancing compression pressure of entrapped air for highly developed soils rich in non-swelling clays and Fe/Al oxides. These results facilitate an improvement of fertilizer management and irrigation to improve soil quality on different soil types.

DEM analysis of cohesive granular shear flow using dynamic adhesion force model – Model validation for contact-dominated regime

When the DEM simulations are performed, the particle stiffness of the Discrete Element Method (DEM) is often reduced to reduce the computational cost. The Dynamic Adhesion/Cohesion Force Model (DAFM/DCFM) was proposed for adhesive/cohesive particles to make the effect of adhesion/cohesion force on the collisional motion of a particle with a reduced particle stiffness equivalent to that of the original system.This study validates the applicability of DCFM to the contact-dominated regime by means of a series of DEM simulations of two-dimensional simple shear flow of cohesive spherical particles. The results demonstrate that DCFM accurately represents the cohesive nature of the original system with respect to the fluid-to-solid phase transition of granular medium due to a reduction in shear rate, as well as the shear stress of the granular medium. It is demonstrated that the bond-breaking model proposed in the present study describes well the validity of DCFM in the contact-dominated regime.

The corrosion behavior of graphene reinforced titanium matrix composites in 3.5 wt% NaCl solution

Graphene is widely preferred as a reinforcement element to enhance mostly mechanical properties of titanium matrix composites due to its unique properties. However, the number of detailed studies is quite limited in the literature on the corrosion properties of graphene reinforced titanium composites. Therefore, the effects of graphene amount on the corrosion properties of titanium composites were evaluated in this study. Pure titanium and graphene‑titanium composites for various amount of graphene (0.15, 0.30 and 0.45 wt%) were produced by powder metallurgy. The electrochemical impedance spectroscopy was used to analyze the corrosion properties of the samples in 3.5 wt% NaCl solution. From the results, TiGr15 sample was observed as maximum corrosion resistance with 6.6939 × 10+5 (Ω·cm2). The cyclic potentiodynamic polarization method results showed that TiGr15 sample (0.0007 mA/cm2) has the lowest corrosion flow rate. Moreover, the SEM-EDX images of the corroded samples showed that the highest cohesion of constituent particles and the least amount of corrosion, particle separation were observed at Ti-0.15 wt% graphene.

Heat transfer of cohesive particles in a rotary drum: Effect of material properties and processing conditions

This study examines the effect of cohesive particle properties and rotary drum operating conditions on heat transfer. Simulations were performed using the Discrete Element Method and Johnson–Kendall–Roberts contact model. Key variables analyzed include material properties (surface energy, particle size, thermal conductivity), fill level, and rotational speed. Angle of repose (AOR) tests were simulated for varying surface energies to establish a correlation between cohesion and bulk properties. Results showed that the AOR was proportional to the particle Bond number and maintaining a constant Bond number across different particle sizes produced similar heating patterns. This enables practical mapping of properties for future modeling and experimentation. Cohesion between particles was found to linearly decrease the rate of heat transfer, whereas adhesion between particles and the drum walls linearly increased it, leading to temperature non-uniformity among particles. Additionally, baffles enhanced heat transfer under cohesive conditions, although their effectiveness decreased with increased adhesion.

Computational modeling of the physical features that influence breast cancer invasion into adipose tissue.

Breast cancer invasion into adipose tissue strongly influences disease progression and metastasis. The degree of cancer cell invasion into adipose tissue depends on both biochemical signaling and the mechanical properties of cancer cells, adipocytes, and other key components of adipose tissue. We model breast cancer invasion into adipose tissue using discrete element method simulations of active, cohesive spherical particles (cancer cells) invading into confluent packings of deformable polyhedra (adipocytes). We quantify the degree of invasion by calculating the interfacial area At between cancer cells and adipocytes. We determine the long-time value of At vs the activity and strength of the cohesion between cancer cells, as well as the mechanical properties of the adipocytes and extracellular matrix in which adipocytes are embedded. We show that the degree of invasion collapses onto a master curve as a function of the dimensionless energy scale Ec , which grows linearly with the cancer cell velocity persistence time and fluctuations, is inversely proportional to the system pressure, and is offset by the cancer cell cohesive energy. When , cancer cells will invade the adipose tissue, whereas for , cancer cells and adipocytes remain de-mixed. We also show that At decreases when the adipocytes are constrained by the ECM by an amount that depends on the spatial heterogeneity of the adipose tissue.

Probing the microstructural properties of metal-reinforced polymer composites

Abstract Microstructural analysis is an important technique to study the extent of interaction between metal fillers and polymers. The aim of this study is to review the investigations on the microstructural properties of metal-reinforced polymer composites. Scanning Electron Microscope (SEM) operating at a magnification range of 2,500× is typically used for examining the microstructure of the composites. Microstructural analysis reveals two key qualitative informations, dispersion and interfacial adhesion. It was observed from the review that flaky metal fillers will maximise dispersion and interfacial adhesion hence leading to improved mechanical, tribological, electrical, and thermal properties of the composites. Utilizing ternary metallic components helps to eliminate aggregation because the cohesion of metal particles is limited. It is important that future microstructural studies evaluate nano-sized fillers as compared to micro-sized ones. Also, it is important to quantitatively correlate the arrangement of the fillers to macro-scale properties and finite element analysis is an important tool that can help achieving this.

Discrete element contact model and parameter calibration of sticky particles and agglomerates

The soil in southwest China is a cohesive soil in which discrete cohesive particles and aggregates coexist. In view of the problem that there are many studies on discrete cohesive particles and a lack of research on aggregates, discrete element software DEM is used to conduct a study on cohesive particles and agglomerates parameter calibration. The angle of repose is selected as the target value to calibrate the simulation parameters of sticky particles. Then, the simulation parameters of the viscous particles are used as the basis for the calibration of the contact parameters of the agglomerates, and shear experiments are conducted on the agglomerates, with the ultimate shear depth and ultimate shear force as target values. The results show that the parameters of the agglomerate are: Normal Stiffness per unit area is 5.627 × 108 N/m3, Shear Stiffness per unit area is 4.359 × 108 N/m3, Critical Normal Stress is 3.5 × 106 Pa, Critical Shear Stress is 4.5 × 106 Pa and Bonded Disk Radius is 5.43 mm. Through the particle sliding friction angle test and the agglomerate compression test, it was verified that the errors of sticky particles were 0.30 % and 0.37 % respectively, and the error of agglomerates was 1.69 %.

Investigation of thermal damage in explosive bridgewire detonators via discrete element method simulations

AbstractExploding bridgewire (EBW) detonators are used to rapidly and reliably initiate energetic reactions by exploding a bridgewire via Joule heating. While the mechanisms of EBW detonators have been studied extensively in nominal conditions, comparatively few studies have addressed thermally damaged detonator operability. We present a mesoscale simulation study of thermal damage in a representative EBW detonator, using discrete element method (DEM) simulations that explicitly account for individual particles in the pressed explosive powder. We use a simplified model of melting, where solid spherical particles undergo uniform shrinking, and fluid dynamics are ignored. The subsequent settling of particles results in the formation of a gap between the solid powder and the bridgewire, which we study under different conditions. In particular, particle cohesion has a significant effect on gap formation and settling behavior, where sufficiently high cohesion leads to coalescence of particles into a free‐standing pellet. This behavior is qualitatively compared to experimental visualization data, and simulations are shown to capture several key changes in pellet shape. We derive a minimum and maximum limit on gap formation during melting using simple geometric arguments. In the absence of cohesion, results agree with the maximum gap size. With increasing cohesion, the gap size decreases, eventually saturating at the minimum limit. We present results for different combinations of interparticle cohesion and detonator orientations with respect to gravity, demonstrating the complex behavior of these systems and the potential for DEM simulations to capture a range of scenarios.

Probing Iceland's dust-emitting sediments: particle size distribution, mineralogy, cohesion, Fe mode of occurrence, and reflectance spectra signatures

Abstract. Characterising the physico-chemical properties of dust-emitting sediments in arid regions is fundamental to understanding the effects of dust on climate and ecosystems. However, knowledge regarding high-latitude dust (HLD) remains limited. This study focuses on analysing the particle size distribution (PSD), mineralogy, cohesion, iron (Fe) mode of occurrence, and visible–near infrared (VNIR) reflectance spectra of dust-emitting sediments from dust hotspots in Iceland (HLD region). Extensive analysis was conducted on samples of top sediments, sediments, and aeolian ripples collected from seven dust sources, with particular emphasis on the Jökulsá basin, encompassing the desert of Dyngjunsandur. Both fully and minimally dispersed PSDs and their respective mass median particle diameters revealed remarkable similarities (56 ± 69 and 55 ± 62 µm, respectively). Mineralogical analyses indicated the prevalence of amorphous phases (68 ± 26 %), feldspars (17 ± 13 %), and pyroxenes (9.3 ± 7.2 %), consistent with thorough analyses of VNIR reflectance spectra. The Fe content reached 9.5 ± 0.40 wt %, predominantly within silicate structures (80 ± 6.3 %), complemented by magnetite (16 ± 5.5 %), hematite/goethite (4.5 ± 2.7 %), and readily exchangeable Fe ions or Fe nano-oxides (1.6 ± 0.63 %). Icelandic top sediments exhibited coarser PSDs compared to the high dust-emitting crusts from mid-latitude arid regions, distinctive mineralogy, and a 3-fold bulk Fe content, with a significant presence of magnetite. The congruence between fully and minimally dispersed PSDs underscores reduced particle aggregation and cohesion of Icelandic top sediments, suggesting that aerodynamic entrainment of dust could also play a role upon emission in this region, alongside saltation bombardment. The extensive analysis in Dyngjusandur enabled the development of a conceptual model to encapsulate Iceland's rapidly evolving high dust-emitting environments.

Bed Stability Control in Pulsed Fluidized-Bed Agglomeration of Instant Riceberry Powder Using an Image-Processing Technique.

The problematic cohesiveness of food powders can commonly be solved using pulsed fluidized-bed agglomeration. However, progressively larger granules may result in unstable fluidization. The aims of this research study were to investigate fluid bed expansion as affected by particle enlargement and to control its stability using an image-processing technique. Instant riceberry powder (IRP) was agglomerated using varied air pulsation frequencies (1, 2.5, and 4 Hz). Bed expansion captured by image processing revealed that expanded bed height decreased with agglomeration time. The results showed an enlargement of agglomerated IRP, expressed in D10, D50, and D90, with narrower distribution presented by span, and an improvement in bulk and reconstitution properties. The reduced Carr index (22-27%) and Hausner ratio (1.28-1.38) presented fair flowability and intermediate cohesiveness, respectively. Additionally, airflow during agglomerate growth was progressively adjusted using the image-processing method to enhance bed hydrodynamic stability, leading to improved process efficiency and product quality. This proposed approach has potential applications in the food powder manufacturing industry, particularly by enhancing the fluidization of cohesive particles with cracks and channels.

Analysis on the mechanical jamming of particle flow using impeller-based rheometer

We simulated the cohesive particle flow in an impeller-based rheometer using Discrete Element Method (DEM), and we focus on the dynamics of particles around the constriction between the blade and its surrounding vessel wall. The results show that mechanical jamming could transiently and intermittently occur in the constriction, but it is limited in a narrow region and short duration. Larger stiffness of particles and lifting flow pattern are more prone to the occurrence of jamming. The scaling law used to speed up the DEM simulation by reducing particle stiffness may fail for particle flow passing through clearance. The mechanical jamming of particles is in low frequency with value <50 Hz and the duration of an individual jamming event is usually <0.04 s. The existence of mechanical jamming is also illustrated by the experiment, where the wear of particle surface is clearly observed with scratches and pits.

Modelling the controlled drug release of push-pull osmotic pump tablets using DEM

The push-pull osmotic pump tablet is a promising drug delivery approach, offering advantages over traditional dosage forms in achieving consistent and predictable drug release rates. In the current study, the drug release process of push-pull osmotic pump tablets is modelled for the first time using the discrete element method (DEM) incorporated with a microscopic diffusion-induced swelling model. The effects of dosage and formulation design, such as delivery orifice size, drug-to-polymer ratio, tablet surface curvature, friction between particles and cohesion of polymer particles, on the drug release performance are systematically analysed. Numerical results reveal that an enlarged delivery orifice significantly increases both the total drug release and the drug release rate. Moreover, the larger the swellable particle component in the tablet, the higher the drug release rate. Furthermore, the tablet surface curvature is found to affect the drug release profile, i.e. the final drug release percentage increases with the increasing tablet surface curvature. It is also found that the drug release rate could be controlled by adjusting the inter-particle friction and the cohesion of polymer particles in the formulation. This DEM study offers valuable insights into the mechanisms governing drug release in push-pull osmotic pump tablets.

Technical note: Optimization of the preparation of cascade impactors collection substrates for airborne metallic ultrafine particle sampling

The characterization of workers’ exposure to airborne metallic ultrafine particles (UFP) has been an increasing issue because of their effects on health, and as many activities are potentially concerned such as welding, oxy-cutting or 3D printing. Determining the particle size distribution of such an aerosol provides a real contribution to the understanding of UFP exposures and associated health effects, as it is directly related to their penetration in the respiratory tract. In this context, it is proposed to optimize the preparation of collection substrates of cascade impactors of airborne metallic UFP. The experimental results confirm that the collection substrates have to be prepared beforehand by coating them with a high-vacuum-resistant silicone grease. The results highlight that this grease has to be preliminarily dissolved in a heptane-based solution with a mass ratio grease-solvent of 7.5%, and then deposited on the substrate with a target height of 9 μm. Applying this protocol ensures a reproducible and representative determination of the particle size distribution, allowing the phenomena of particle bouncing and reentrainment to be significantly reduced. It is also shown that coated collection substrates remain stable for several months in terms of mass, and that the samples collected remain stable during transport thanks to the improvement of particle cohesion on the coated membrane.

Design Principle and Development Trends of Silicon-Based Anode Binders for Lithium-ion Batteries: A Mini Review

Abstract: Silicon (Si), recognized as a promising alternative material for the anodes of lithium-ion batteries, boasts a high theoretical specific capacity and abundant natural availability. During the preparation of silicon-based anodes, binders play a pivotal role in ensuring the cohesion of silicon particles, conductive agents, and current collectors. The structure and performance of these binders are critical for the mechanical stability, electrical conductivity, and stress dissipation capacity of the anodes. This review initially outlines the structural characteristics of various binders, including linear, branched, and three-dimensional cross-linked types. It then delves into the relationship between the structure and properties of these binders in the context of their application in high-performance lithium-ion batteries, focusing on their mechanical properties, electrical conductivity, and self-healing capabilities. Particular attention is given to the design strategies for binders that facilitate stress dissipation, with an emphasis on integrating multifunctional polymer binders renowned for their superior conductive and self-healing features. Such binders contribute to the formation of a robust three-dimensional network structure via multiple bonding mechanisms, including chemical, non-covalent, and coordination interactions. This configuration significantly enhances the adhesion between silicon particles, thereby facilitating the efficient dissipation of stress, which is a key aspect for ensuring the long-term cycling stability of lithium-ion batteries. Lastly, the paper explores future development directions for silicon anode binders, advocating for a thorough investigation into the synergy of diverse structural and functional combinations, with the aim of advancing the performance and practical application of silicon-based lithium-ion batteries.

A Review: Novel Granulation Technology

All the pharmaceutical Active pharmaceutical Ingredients (API) and Pharmaceutical excipients will have different particle size. While formulating a dosage form, particles from raw materials will tend to separate from other due to their rheological properties. There could be a condition where fine particles separate from the larger particles causing demixing or uneven distribution of active with its excipients leading to tablet content uniformity issue. To overcome this problem, particle enlargement or particle cohesiveness with or without additional aid is necessary, which could be achieved by granulation. Hence granulation technology is important in the formulation of pharmaceutical oral solid dosage form. Granulation is the process of adhering fine particles agglomerate into a large particle using two most common methods i.e. wet granulation and dry granulation/compaction. Day by day technological innovation is happening in all fields and pharmaceutical granulation process is also not an exemption. The objective of present review is to focus the novel granulation technology and how it is differing from the conventional granulation technology.

Plugging of pipes by cohesive particles. Computed tomography investigation and theoretical analysis

Flow regimes leading to clogging of pipes exist for most multiphase flows with cohesive particles. Although plugging is critical in many industrial and medical applications, there are few records describing the details of the process. To address the problem, we conduct a computed tomography (CT) study of plugging in a cohesive ice slurry. We run experiments for ice concentration of 15%, Re∼3500, particle size 0.2-0.4 mm, and their surface energy ∼150 mJ/m2. The CT scans, combined with experimental logs of the main flow parameters, revealed the formation of deposits around the orifice inserted into the pipe, with a complete blockage formed downflow the orifice. The deposition efficiency of ice was relatively low ∼ 10−3. Reproducing the experimental deposition efficiency with the Lagrangian CFD model, we extracted the probability of particle capture at the orifice, which was about 0.5%. The simulation results illustrated how inter-particle interactions hindered the plugging.

Study on anti-seepage mechanism of attapulgite-modified loess in Northwest China

Loess is distributed widely in the arid areas in northwest China. Lanzhou city is located on the loess plateau, covered by a large area of deep collapsible Malan loess. Collapsible loess is a soft soil in engineering. It has a specific bearing capacity under dry conditions but will collapse after being immersed in water, which is unfavorable to engineering construction. This paper used the attapulgite abundant in the Zhangye City of Gansu Province as a modifier to improve the loess. The permeability test tested the permeability coefficient of the specimens under different dosages of attapulgite. The anti-permeability principle of attapulgite-modified loess was analyzed from the microscopic perspective by electron microscopy scanning (EMS) and nuclear magnetic resonance (NMR). The test results show that the permeability coefficient of attapulgite-modified loess decreases significantly compared with pure loess, but the permeability coefficient decreases gently when the content of attapulgite exceeds 10%. It was found that the anti-permeability mechanism of the modified loess was that the cohesive attapulgite particles filled the macropores of the loess particles, and the acicular attapulgite combined the loess particles to form a sheet structure, which reduced the porosity and permeability of the modified soil.

Cohesive particle–fluid systems: An overview of their CFD simulation

AbstractSolid particles may experience different kinds of cohesive forces, which cause them to form agglomerates and affect their flow in multiphase systems. When such systems are simulated through computational fluid dynamics (CFD) programs, appropriate modelling tools must be included to reproduce this feature. In this review, these strategies are addressed for various systems and scales. After an introduction of the different forces (van der Waals, electrostatic, liquid bridge forces, etc.), the modelling approaches are categorized under three methodologies. For diluted slurries of very fine particles, many researchers succeeded with pseudo‐single phase approaches, employing a model for the non‐Newtonian rheology. This was especially popular for sludges in anaerobic digestions or certain types of soils. In other cases, continuum‐based approaches seem to be more adequate, including cohesiveness in the kinetic theory of granular flows or the restitution coefficient. Geldart‐A particles experiencing van der Waals forces are the primary focus of such studies. Finally, when each particle is modelled as a discrete element, the cohesive force can be directly specified; this is especially widespread for the wet fluidization case. For each of these approaches, a general overview of the main strategies, achievements, and limits is provided.

Mixing performance of cohesive particles in a double barrel with differential velocity based on DEM

The double barrel with differential velocity (DBDV) was proposed to improve the mixture quality. However, the mixing mechanism of cohesive particles in the DBDV is unclear. So, the mixing performance of cohesive particles in the DBDV was studied. The cohesive force between particles was simulated using a viscous contact model. The effects of linear velocity, inclination and cohesive force on the mixing performance were studied. The mixing process of particles was analyzed through mixing uniformity, mixing time, velocity, and contact forces. The results show that excessive cohesion cannot promote the dispersion of particles in the mixture, affecting production efficiency. The motion intensity of particles in the differential region is stronger than that in the non-differential region. The differential zone is suitable for particle motion with high cohesion. This study reveals the detailed mixing behavior of cohesive particles in DBDV, which provides operational guidance for the actual road material mixing process.