Agglomerate Size Research Articles

Microphysical Interactions Determine the Effectiveness of Solar Radiation Modification via Stratospheric Solid Particle Injection

AbstractRecent studies have suggested that stratospheric aerosol injection (SAI) of solid particles for climate intervention could reduce stratospheric warming compared to injection of . However, interactions of microphysical processes, such as settling and coagulation of solid particles, with stratospheric dynamics have not been considered. Using a global chemistry‐climate model with interactive solid particle microphysics, we show that agglomeration significantly reduces the backscatter efficiency per unit of injected material compared to mono‐disperse particles, partly due to faster settling of the agglomerates, but mainly due to increased forward‐ over backscattering with increasing agglomerate size. Despite these effects, some materials substantially reduce required injection rates as well as perturbation of stratospheric winds, age of air and stratospheric warming compared to injection of , with the most promising results being shown by 150 nm diamond particles. Uncertainties remain as to whether stratospheric dispersion of solid particles is feasible without formation of agglomerates.

Numerical study of proton exchange membrane water electrolyzer performance based on catalyst layer agglomerate model

In this work, a two-dimensional two-phase model of proton exchange membrane water electrolyzer (PEMWE) is developed, in which the catalyst layer (CL) is represented using agglomerate model. The effects of CL composition, porous transport layer (PTL) material properties and operating conditions on PEMWE performance are investigated. The results indicate that small size of catalyst agglomerate around 0.25 μm would benefit PEMWE performance. Appropriate increase of catalyst loading, porosity and ionomer volume fraction in the CL improves PEMWE performance, but their further increment leads to high mass transfer resistance, limiting the improvement of electrolyzer performance. The porosity and ionomer volume fraction of the catalyst layer are suggested to be lower than 0.5 and 0.6, respectively. The catalyst loading should be lower than 1.5 mg cm−2 when the CL porosity is higher than 0.3. The PTLs with high permeability, porosity and low contact angle is beneficial for the gas–liquid two-phase flow and avoiding the overheat and water shortage in the electrolyzer. Increasing the inlet velocity accelerates the bubble removal process, but might results in significant temperature drop, degrading the PEMWE performance. The most suitable temperature of inlet liquid is around 353.15 K. The results provide important guidance for the optimization design of high-performance PEMWE.

Numerical study of aluminum combustion with agglomerate size distribution in solid rocket motor

The aluminum agglomerate size distribution plays an important role in influencing the particle distributed combustion in motor, which subsequently affects the performance of solid rocket motor significantly. In this work, a three-phase model to describe distributed combustion of aluminum agglomerates is established based on the Eulerian-Lagrangian method. Then, the agglomerate size, including mono size and distributed size, is studied to reveal its effect on aluminum combustion and motor flow field. The simulated results indicate that the increasing agglomerate mono size observes the obvious decrease of the average temperature inside the motor combustion chamber, implying the low combustion efficiency of large agglomerate size. When considering the agglomerate size distribution, the size distribution mode and the mean size D43 determine the combustion efficiency together. In particular, even the mean size is similar, with different distribution mode, like skewed distribution, bimodal or trimodal distribution, the combustion efficiency and flow field parameters are nonnegligible different. However, when the size distribution mode is the same and the peak range is similar, the mean size D43 becomes the only and predominant factor as the mono size.

Dependence of photocatalytic efficiency of titania-carbon nanotube nanocomposites on optoelectrical properties and colloidal stability

The correlation of photocatalytic efficiency of titania–amorphous (nitrogen doped) carbon nanotubes (TiO2–a(N)CNT) nanocomposites with colloidal and optoelectrical properties of the photocatalysts was investigated. TiO2–aNCNT and TiO2–aCNT exhibited narrow zeta potential variation, high polydispersity index, and large agglomerate size across the pH range 1–8. Despite the poor colloidal stability, TiO2–aNCNT exhibited superior degradation for high molecular weight reactive dyes, RR 120 and Remazol brilliant blue (RBB) with 55 mg.L−1 of RR 120 mineralized under solar irradiation. The photocatalytic performance for TiO2–aNCNT and TiO2–aCNT correlated with the respective energy band gaps 3.01 and 3.14 eV, Ubarch tailing energies. Cyclic voltammetry showed a narrow peak-to-peak separation (ΔEp) of 200.7 V (vs Ag/AgCl) for TiO2–aNCNT thus confirming enhanced electron transfer kinetics. Electron impedance spectroscopy confirmed low charge transfer resistance for TiO2–aNCNT. Herein it is demonstrated that optoelectrical properties are superior in driving photocatalytic reactions.

Proflavine binding to La-Sr perovskite manganite nanoparticles at temperatures above and below the Сurie temperature

The magnetic properties of La1-xSrxMnO3 (LSMO) nanoparticles within the ferromagnetic region (x ≈ 0.2–0.5) enable their application in two types of cancer treatment: chemotherapy drug delivery and self-controlled hyperthermia. Single-phase La0.80Sr0.20MnO3 nanoparticles were prepared by the sol-gel process followed by mechanical processing. Sample characterization was performed by using XRD, TEM, EPR, and DLS techniques. The encapsulation efficiency of proflavine to the nanoparticles was determined via spectrophotometry. The mean size of crystallites of LSMO nanoparticles is 18 nm, and the Curie temperature is 319 K. Bare LSMO particles do not form a colloidally stable aqueous suspension; they exhibit a zeta potential close to zero and provide micro-sized aggregates. Application of sodium citrate for their stabilization leads to a decrease in the size of agglomerates and to a highly negative zeta potential of –33 mV. The efficiency of proflavine sorption by LSMO nanoparticles increases significantly above the Curie temperature, from 16.1 % at 298 K to 26.2 % at 333 K. This increase is attributed to the partial disruption of nanoparticle agglomerates in suspension after the LSMO phase loses its ferromagnetic order. In summary, heating LSMO nanoparticles above the Curie temperature increases the degree of drug loading on the nanoparticles.

The enabling effects of digital technology on the quality of firm development: Insights and implications

Firms are the fundamental units driving the development of regional systems, and their enhancement in overall strength determines the effectiveness of industrial collaborative innovation networks, serving as a crucial support for the high-quality development of urban agglomerations. In the digital era, how firms can improve their overall strength to enhance their supporting role in the construction of regional industrial networks is a matter of significant interest. Therefore, as a new driving force for firm development, exploring the impact of digital technology on firm development quality is of great importance. From the perspective of the enabling effects of digital technology, this paper takes A-share listed firms within China's five major urban agglomerations as the research subjects, utilizing panel data from 2012 to 2022. Through theoretical analysis and empirical testing using various econometric methods—including the fixed effects model, two-stage least squares regression model, and mediation effect model—the study investigates the impact of digital technology application on firm development quality and its underlying mechanisms. This study finds that the application of digital technology significantly enhances the quality of firm development, and as the level of digital technology application deepens, firms' development continues to improve. From the perspective of enabling factors, digital technology application can promote the improvement of firm development quality by activating innovation vitality, alleviating financing constraints, and reducing human resource management costs. The heterogeneity analysis results reveal that the impact of digital technology application on firm development quality exhibits various heterogeneous characteristics, including differences in urban agglomeration, ownership structure, and firm size.

Effect of Antisolvent Used to Regenerate Cellulose Treated with Ionic Liquid on Its Properties.

The solvolysis reaction with ionic liquids is one of the most frequently used methods for producing nanometer-sized cellulose. In this study, the nanocellulose was obtained by reacting microcrystalline cellulose with 1-ethyl-3-methylimidazolium acetate (EmimOAc). The aim of this research was to determine the influence of various antisolvents used in the regeneration of cellulose after treatment with ionic liquid on its properties. The following antisolvents were used in this research: acetone, acetonitrile, water, ethanol and a mixture of acetone and water in a 1:1 v/v ratio. The nanocellulose was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM) and elemental analysis (EA). The results show that the antisolvent used to regenerate cellulose after the solvolysis reaction with EmimOAc affects its properties. Water, ethanol and a mixture of acetone and water successfully removed the used ionic liquid from the cellulose structure, while acetone and acetonitrile were unable to completely remove EmimOAc from the cellulosic material. The results of the XRD analysis indicate that there is a correlation between the ionic liquid content in the regenerated cellulose and its degree of crystallinity. Among the tested solvents, water leads to the effective removal of EmimOAc from the cellulose structure, which is additionally characterized by the smallest particle size and non-formation of agglomerates.

Disruptive content, cross agglomeration interaction, and agglomeration replacement: Does cohesion foster strength?

A trend in the academic field is agglomerations among scholars to generate knowledge with a disruptive influence on science and technology; however, the benefits have not been fully substantiated. This paper analyzes over 660,000 papers on artificial intelligence published from 1961 to 2023. We propose a method to calculate the innovative capacity of disruptive knowledge based on the similarity of historical, current, and future keywords, finding that scholars who commence their scientific endeavors earlier possess a heightened capability for disruptive knowledge innovation as Dkc index. The analysis reveals that multiagglomeration scholars have the highest average number of publications and citations, followed by agglomeration-flow scholars. Moreover, a larger agglomeration results in a lower ability to disrupt and consolidate knowledge innovation. Multiagglomeration and agglomeration-flow scholars harm disruptive/consolidative innovations. However, as the agglomeration effect intensifies, these two types of scholars from the disruptive perspective and multiagglomeration scholars from the consolidation perspective have a diminishing marginal effect on innovation capacity. The agglomeration size acts as a partial intermediary in the Multi→Size→Dkc index from the dual perspective and as a full mediator in the Flow→Size→Dkc index from the disruptive perspective, but only with a direct effect from the consolidative perspective.

Effect of aluminum and ammonium perchlorate particle sizes on the condensed combustion products characteristics of aluminized NEPE propellants

Aluminum (Al) is usually added to solid propellants to improve the combustion performance, however the condensed combustion products (CCPs) especially the large agglomerates generated from aluminum combustion can reduce the specific impulse of the engine, and result in two-phase loss, residue accumulation and throat liner ablation. Al and ammonium perchlorate (AP), as important components of NEPE propellants, can affect the formation process of the CCPs of aluminized NEPE propellants. To clarify the effect of Al and AP particle sizes on the properties of the CCPs of aluminized NEPE propellants, a constant-pressure quench vessel was adopted to collect the combustion products of four different formulations of NEPE propellants. It was found that the condensed combustion products are mainly divided into aluminum agglomerates and oxide particles, the diameter of the aluminum agglomerates of these four different formulations of NEPE propellants at 7 MPa was smaller than that in 3 MPa, and the shells of the aluminum agglomerates were smoother and the spherical shape was more perfect. X-ray diffraction analysis of the CCPs of the four NEPE propellants under 3 MPa revealed the presence of both Al and Al2O3. With the increase of the particle size of Al and AP, the oxidation degree of aluminum particles decreases. The particle size of the CCPs of the four different formulations of NEPE propellants under 1 and 3 MPa was analyzed by using a laser particle size analyzer, it is found that the increase of AP particle size is helpful to reduce the size of condensate combustion products. Based on the classical pocket theory, establishing a new agglomeration size prediction model, which can be used to predict the agglomeration size on the burning surface. Compared with the empirical model, the new agglomeration size prediction model is in good agreement with the experimental results.

Quantifying electron transport in aggregated colloidal suspensions in the strong flow regime

Electron transport in complex fluids, biology, and soft matter is a valuable characteristic in processes ranging from redox reactions to electrochemical energy storage. These processes often employ conductor-insulator composites in which electron transport properties are fundamentally linked to the microstructure and dynamics of the conductive phase. While microstructure and dynamics are well recognized as key determinants of the electrical properties, a unified description of their effect has yet to be determined, especially under flowing conditions. In this work, the conductivity and shear viscosity are measured for conductive colloidal suspensions to build a unified description by exploiting both recent quantification of the effect of flow-induced dynamics on electron transport and well-established relationships between electrical properties, microstructure, and flow. These model suspensions consist of conductive carbon black (CB) particles dispersed in fluids of varying viscosities and dielectric constants. In a stable, well-characterized shear rate regime where all suspensions undergo self-similar agglomerate breakup, competing relationships between conductivity and shear rate were observed. To account for the role of variable agglomerate size, equivalent microstructural states were identified using a dimensionless fluid Mason number, [Formula: see text], which allowed for isolation of the role of dynamics on the flow-induced electron transport rate. At equivalent microstructural states, shear-enhanced particle-particle collisions are found to dominate the electron transport rate. This work rationalizes seemingly contradictory experimental observations in literature concerning the shear-dependent electrical properties of CB suspensions and can be extended to other flowing composite systems.

Quantification of agglomerate size and interparticle forces with a modified Hausner ratio

A model is introduced in this study that establishes a relationship between bed voidage, agglomerate size, and the magnitude of interparticle forces (IPFs) with a focus on Geldart group C powders. A modified Hausner ratio (MHR), defined as the ratio of particle density to tapped bulk density for this specific group of powders, is a critical parameter of the model. The model leads to two fundamental equations. The first equation suggests that the ratio of agglomerate size to particle size is directly proportional to the square of the MHR. The second equation is a linear relationship between the ratio of IPFs and the weight of a particle with the fourth power of MHR. These equations were validated by comparing their outcomes for agglomerate size and magnitude of IPFs with the estimates of other experimental approaches. The results for Geldart group C powders showed that IPFs are at least an order of magnitude greater than the weight of a particle leading to the formation of agglomerates, which are at least three times greater than the primary particles. The proposed equations may not be applied to nanoparticles and powders with wide size distributions, necessitating further developments to achieve more accurate predictions for these cases.

Bioinspired green synthesis of copper, nickel, and hybrid nanoparticles using Myristica Fragrans seeds: Biomedical applications and beyond

Nanotechnology focuses on materials at the molecular and atomic levels, with sizes ranging from 0.1 to 100 nm. This study explores the synthesis and characterization of copper oxide (CuO), nickel oxide (NiO), and hybrid nanoparticles using an aqueous seed extract from Myristica fragrans. The nanomaterials underwent comprehensive characterization employing various techniques: UV analysis, FTIR spectroscopy, XRD, TGA, EDX and SEM. We explored their biological applications through antioxidant and antibacterial assays. UV analysis determined the optical absorption spectra values for CuO, NiO and hybrid nanoparticles. FTIR analysis confirmed functional groups in the plant extract responsible for capping and reducing the reaction medium. XRD and SEM analysis demonstrated the crystalline nature and morphology of the nanoparticles. CuO nanoparticles exhibited polyhedral morphology, while NiO nanoparticles were primarily spherical with some agglomeration. The CuO-NiO hybrid nanoparticles showed a wurtzite morphology with significant agglomeration and larger mean size than CuO and NiO nanoparticles. EDX indicated higher quantities of Cu and Ni. XRD spectra revealed the average particle sizes of nanoparticles. TGA indicated the thermal stability of the nanoparticles, with hybrid nanoparticles being the most stable. The nanoparticles exhibited excellent antioxidant activity, with hybrid nanoparticles showing the highest values in measuring total antioxidant capacity, total reducing power (TRP), ABTS assay, and DPPH-free radical scavenging assay at 400 μg/mg. Antibacterial assays against multidrug-resistant bacterial strains demonstrated that antibiotics-coated hybrid nanoparticles exhibited potent antibacterial properties against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. In conclusion, CuO, NiO, and CuO-NiO hybrid nanoparticles mediated by Myristica fragrans showcase promising characteristics for various applications, especially in biomedical and clinical settings. The nanoparticles eco-friendly synthesis and biocompatible nature make them attractive candidates for future research and development.

Effect of pH on the green synthesis of ZnO nanoparticles using Sorghum bicolor seed extract and their application in photocatalytic dye degradation

This work proposes the green synthesis of ZnO nanoparticles (NPs) using an aqueous extract of sorghum seed (Sorghum bicolor L. Moench). The effect of synthesis pH on the structural, morphological, and surface properties of ZnO NPs is investigated. The results revealed that pH influences crystallinity, surface-adsorbed functional groups, agglomeration, and nanoparticle size. ZnO NPs synthesized at pH 11 exhibited the best properties for complete photocatalytic degradation of methylene blue (MB) dye under sunlight in 40 min.

Effect of dispersion behavior of silica fume on the rheological properties and early hydration characteristics of ultra-high strength mortar

Silica fume plays a crucial role in ultra-high performance cementitious materials, but its dispersion, influenced by varying densification levels, leads to different degrees of agglomeration. However, the precise impact of this on rheological properties and early hydration characteristics of ultra-high performance cementitious materials remains unclear. This study assesses the impact of highly densified silica fume (HDSF), moderately densified silica fume (MDSF), and raw silica fume (RSF) on the rheological prperties of ultra-high strength mortar (UHSM). Additionally, the early hydration characteristics of UHSM influenced by these silica fumes are investigated through both heat of hydration and penetration resistance methods. The results showed that HDSF contained numerous large agglomerates, contrasting with MDSF and RSF, where the agglomerate sizes were comparable to those of cement particles. As the content of HDSF increased, the yield stress, viscosity, and thixotropy of UHSM gradually rose, accompanied by a notable decrease in hydration rate. Conversely, increasing MDSF and RSF content initially decreased and then increased these rheological properties, while the hydration rate remained relatively unchanged. The distribution behavior of the silica fumes influences the rheological properties of UHSM through water film thickness (particle spacing). Large agglomerates in HDSF reduce the activity of the entire cementitious system, significantly decreasing the hydration rate. In contrast, MDSF and RSF primarily influence the particle spacing within the cementitious system, subsequently impacting the hydration rate. This study provides theoretical insights and practical guidance for construction professionals in selecting appropriate silica fume for designing and regulating ultra-high performance cementitious materials performance.

Stability of bubble-particle hetero-coagulates accessed by atomic force microscopy to understand the froth flotation of agglomerating hydrophobic fines

The key microprocesses, which determine the efficiency in froth flotation are the formation and breakage of particle-bubble hetero-coagulates. Agglomeration can be used to increase the recovery of fine particles < 20 µm. Here the stability of hetero-coagulates consisting of agglomerates and gas bubble determines the process performance. Therefore, the stability of agglomerate-bubble hetero-coagulates was accessed by atomic force microscopy (AFM) on particle-laden gas bubbles, agglomerates and pristine gas bubbles without particles in the interface. The force and work of adhesion from AFM measurements were compared to the detaching force and the detaching energy that act on agglomerate-bubble and particle-bubble hetero-coagulates under turbulent conditions, similar to those in a flotation cell. This comparison provides the maximum size of agglomerates and single particles that can remain attached to the gas bubbles at a given energy dissipation rate. The results suggest that the size of agglomerates attached to gas bubbles can grow beyond the Kolmogorov length, which limits the size of agglomerates under turbulent conditions. The findings are supported by in-line probe images of agglomerate-bubble hetero-coagulates that were captured in an aerated stirred tank under turbulent conditions. It was further shown that the particle detachment from particle-laden bubbles is governed by the deformation of the underlying gas bubble and the local particle coverage.

Spherical agglomeration kinetics: A mechanistic approach

Spherical agglomeration, a process of in-suspension particle size enlargement, can substantially improve critical quality attributes of powders. In this work, a paracetamol-heptane-water system is used to investigate the kinetics of spherical agglomeration, demonstrating for the first time the influence of true bridging liquid to solid ratio (TBSR) and suspension loading on the evolving size, shape and density of agglomerates. A critical range of TBSR is identified where robust agglomerates are formed that are round, moderately dense, and have a controlled size distribution. Immersion nucleation, drop breakage, and agglomerate densification by impact are the controlling rate processes. Increasing mixing intensity reduces agglomerate size, porosity and agglomeration time. Increasing solids loading increases agglomeration time while yielding smaller agglomerates with lower porosity. A first order consolidation model quantitatively predicts the agglomeration kinetics as well as agglomerate properties with increasing TBSR, and is a powerful tool for design and scale up.

Cutting-Edge Machine Learning Techniques for Accurate Prediction of Agglomeration Size in Water–Alumina Nanofluids

Cutting-Edge Machine Learning Techniques for Accurate Prediction of Agglomeration Size in Water–Alumina Nanofluids

Powder agglomeration in continuous powder feeding by twin-screw feeder

The presence of powder agglomerates results in product with poor content uniformity and intermittent high potency in the processing of pharmaceutical powders.We developed a novel and easy-to-implement methodology, applying image analysis, to quantify the size of powder agglomerates when a powder passes through a screw feeder. Subsequently, agglomeration tendencies of twenty-one pharmaceutical powders were examined and classified. Notably, both the size and endurance of agglomerates were quantified, and our study revealed that the agglomeration tendency of powders can be explained by particle size and compressibility: Powders with small particle size (D50 < 30 μm), and large compressibility (> 35% at 15 kPa normal stress) tend to form large and enduring agglomerates, which can be difficult to eliminate in downstream processes. The study also illustrates how two materials, one that produces enduring and the other unenduring agglomerates, display substantially different content uniformity in the final product after being processed semi-continuously.

Atrazine degradation through a heterogeneous dual-effect process using Fe–TiO2-allophane catalysts under sunlight

This study investigated the novel application of Fe–TiO2-allophane catalysts with 6.0 % w/w of iron oxide and two TiO2 proportions (10 % and 30 % w/w) for degrading atrazine (ATZ) using the heterogeneous dual-effect (HDE) process under sunlight. Comparative analyses with Fe-allophane and TiO2-allophane catalysts were conducted in both photocatalysis (PC) and HDE processes. FTIR spectra reveal the unique hydrous feldspathoids structure of allophane, showing evidence of new bond formation between Si–O groups of allophane clays and iron hydroxyl species, as well as Si–O–Ti bonds that intensified with higher TiO2 content. The catalysts exhibited an anatase structure. In Fe–TiO2-allophane catalysts, iron oxide was incorporated through the substitution of Ti4+ by Fe3+ in the anatase crystal lattice and precipitation on the surface of allophane clays, forming small iron oxide particles. Allophane clays reduced the agglomeration and particle size of TiO2, resulting in an enhanced specific surface area and pore volume for all catalysts. Iron oxide incorporation decreased the band gap, broadening the photoresponse to visible light. In the PC process, TiO2-allophane achieves 90 % ATZ degradation, attributed to radical species from the UV component of sunlight. In the HDE process, Fe–TiO2-allophane catalysts exhibit synergistic effects, particularly with 30 % w/w TiO2, achieving 100 % ATZ degradation and 85 % COD removal, with shorter reaction time as TiO2 percentage increased. The HDE process was performed under less acidic conditions, achieving complete ATZ degradation after 6 h without iron leaching. Consequently, Fe–TiO2-allophane catalysts are proposed as a promising alternative for degrading emerging pollutants under environmentally friendly conditions.

Physically cross-linked PVA/f-MWCNTs nanocomposite hydrogel with enhanced thermal, mechanical, and dielectric properties

This work offers a new method for the preparation of poly (vinyl alcohol)/f-MWCNTs nanocomposite hydrogel. Employing a physical cross-linking method, fabricated high-strength nanocomposite hydrogel in one step at room temperature without following the traditional repeated freeze-thaw method. Optical microscopy images indicate the uniform dispersion of f-MWCNTs in the PVA matrix with average agglomerate size of 5–6 µm. Morphology investigation showed entangled, more dense network structure after addition of f-MWCNTs. Scissoring of inter chain H-bonding and establishing of intermolecular H-bonding between -OH and -COOH group of PVA and f-MWCNTs examined by ATR-FTIR. Delay in thermal degradation of PVA/f-MWCNTs nanocomposite hydrogel with f-MWCNTs suggested by thermos-gravimetry analysis. Improved melting and crystalline temperature examined by differential scanning calorimetry. PVA/f-MWCNTs nanocomposite hydrogel showed ⁓ 5 and 6 times of modulus and hardness respectively than pristine PVA hydrogel. Oscillatory rheology analysis suggests the robust gel-like network formed upon addition of f-MWCNTs into the PVA matrix. PVA/f-MWCNTs nanocomposite hydrogel showed 13 times dielectric constant than pristine PVA hydrogel along with small dielectric loss investigated by broadband dielectric spectroscopy (BDS). Enhanced thermal, mechanical and dielectric properties make the fabricated PVA/f-MWCNTs nanocomposite hydrogel a potential candidate for the energy storage device and electronics application.