Effect Of Particle Size Distribution Research Articles

Thermal conductivity of MX80 powders-granules mixture and its prediction for high-level radioactive waste repository

Bentonite granules and their mixtures with powders are considered to be a preferred sealing material for filling gaps between buffer layer and surrounding rock in high-level radioactive waste (HLW) repository. Due to continuous release of decay heat from nuclides, thermal conductivity of bentonite granules must be assessed. In this study, the effects of water content, dry density, temperature on the thermal conductivity in the directions parallel (λpar) and perpendicular (λperp) to the bedding plane of MX80 powders-granules mixture (PGM) were investigated by thermal probe technique. Test results showed that the thermal conductivity of powdered bentonite (PB) was higher than that of PGM and λpar was higher than λperp. With increasing water content, the difference rate (δPSD) in thermal conductivity between PB and PGM increased, and anisotropy coefficient α (a ratio of λpar to λperp) decreased, while the effects of dry density and temperature on δPSD and α were not obvious. The factor importance was analyzed, and results showed that the effects of water content, dry density, temperature, and particle size distribution decreased successively. A modified geometric mean (MGM) model for predicting thermal conductivity of PGM with temperature is proposed and it predicted thermal conductivity of MX80 PGM well.

Fabrication of high-performance recrystallized silicon carbide ceramic membrane based on particle packing optimization

Overcoming the challenges associated with achieving high uniformity and connectivity of pore channels in ceramic membranes, we designed silicon carbide ceramic membrane derived from the recrystallization process based on the Dinger-Funk equation of the closest-packing model with various grain grading. Furthermore, the effects of particle size distribution on the resulting microstructure and pore architecture of the ceramic membrane was also explored. The findings corroborated the critical importance of raw material particle size distribution in controlling pore size distribution and morphology. After sintering at 1900oC, the silicon carbide ceramic membrane, benefiting from ideal particle packing, exhibited a remarkably uniform pore structure. Notably, the most probable pore size constituted over 70%, while achieving an open porosity of 51.3% even without the addition of pore-forming agents. The silicon carbide ceramic membrane also demonstrated exceptional hydrophilicity (water contact angle:∼0o), impressive water permeation (1210 L·m-2·h-1·bar-1), coupled with efficient turbidity removal (∼100%) in carbon black wastewater treatment applications. Additionally, membrane regeneration proved effective using a dilute NaOH solution backwash, achieving a flux recovery efficiency of 98%. This strategy had directive significance for designing high-performing silicon carbide ceramic membranes.

Effects of Particle Size Distribution on the Physicochemical, Functional, and Structural Properties of Alfalfa Leaf Powder

To explore the effects of particle size distribution on its physicochemical, functional, and structural properties, alfalfa leaf powders with mean particle sizes (D50) of 506.1, 246.3, 209.8, 92.01, and 20.68 μm were prepared by sieving. The physicochemical, functional, and structural properties of alfalfa were compared, and correlation and principal component analyses were conducted. As the D50 of alfalfa leaf decreased, the bulk density, tap density, and the swelling capacity increased first and then decreased, but the compressibility, transition temperature, and melting temperature exhibited an opposite trend. The solubility, lightness, and inhibition of angiotensin-converting enzymes and tyrosinase were enhanced. Specifically, the alfalfa leaf with a D50 of 209.8 μm exhibited a higher bulk density and swelling capacity and a lower compressibility, transition temperature, and melting temperature. The alfalfa leaf with a D50 of 20.68 μm presented better solubility, lightness, and inhibition of angiotensin-converting enzymes and tyrosinase. Additionally, the surface roughness and the number of surface hydroxyls improved and the crystallinity index decreased, but the type of surface functional groups was unchanged. These changes in microstructure can provide an explanation for the trend of the physicochemical and functional properties. Moreover, based on the results of the correlation analysis and principal component analysis, it can be concluded that there are strong correlations among the particle size, physicochemical properties, and functional properties of alfalfa leaf. Overall, this conclusion can help determine the appropriate grinding particle size range for alfalfa leaf in different functional food products.

Utilizing DEM and interpretable ML algorithms to examine particle size distribution's role in small-strain shear modulus of gap-graded granular mixtures

This study merges macroscale and microscale analyses with interpretable machine learning (ML) algorithm to explore the effect of particle size distribution (PSD) on the small-strain shear modulus (G0) of gap-graded granular mixtures. For this purpose, a database containing 610 groups of data samples was generated by conducting numerical triaxial compression simulations using the discrete element method (DEM). The simulations were carried out using the well-recognized DEM program PFC3D. The influence of isotropic confining pressure (p′), void ratio (e), non-plastic fines content (FC), particle size ratio (Rd), particle size ratio of coarse particles (Dmax/Dmin) and particle size ratio of fine particles (dmax/dmin) on the G0 were discussed in detail. Furthermore, the eXtreme Gradient Boosting (XGBoost) algorithm was utilized, and it was enhanced through a hyperparameter tuning process known as Bayesian optimization (BO) to improve the predictive accuracy of G0 model. Finally, the predictive outcomes of the BO-XGBoost model were interpreted using the SHapley Additive exPlanations (SHAP) method, addressing the technical gap associated with the lack of interpretability in ML models. Meanwhile, the local and global feature variable importance in nonlinear models was also elucidated to provide intuitive insight for the user. The analysis demonstrates that the outcomes from both macroscale and microscale assessments correlate well with the findings obtained through the BO-XGBoost-SHAP approach, facilitating the incorporation of ML model predictions into decision-making processes.

Self-micellizing solid dispersion of thymoquinone with enhanced biopharmaceutical and nephroprotective effects

The present study was designed to develop a self-micellizing solid dispersion (SMSD) containing Thymoquinone (TQM), a phytonutrient obtained from Nigella sativa seeds, aiming to improve its biopharmaceutical and nephroprotective functions. The apparent solubility of TQM in polymer solutions was used to choose an appropriate amphiphilic polymer that could be used to make an SMSD system. Based on the apparent solubility, Soluplus® was selected as an appropriate carrier, and mixing with TQM, SMSD-TQM with different loadings of TQM (5–15%) was made by solvent evaporation and freeze-drying techniques, respectively, and the formulations were optimized. The optimized SMSD-TQM was evaluated in terms of particle size distribution, morphology, release characteristics, pharmacokinetic behavior, and nephroprotective effects in a rat model of acute kidney injury. SMSD-TQM significantly improved the dissolution characteristics (97.8%) of TQM in water within 60 min. Oral administration of SMSD-TQM in rats exhibited a 4.9-fold higher systemic exposure than crystalline TQM. In a cisplatin-induced (6 mg/kg, i.p.) acute kidney-damaged rat model, oral SMSD-TQM (10 mg/kg) improved the nephroprotective effects of TQM based on the results of kidney biomarkers and histological abnormalities. These findings suggest that SMSD-TQM might be efficacious in enhancing the nephroprotective effect of TQM by overcoming biopharmaceutical limitations.

Modeling the temperature-programmed reduction of metal oxide catalysts by considering the particle-size distribution effect

Hydrogen temperature-programmed reduction (H2-TPR) has become a very useful and common technique for the chemical characterization of solids as it is sensitive to the study of reducible species in catalysis and is considered to be a fingerprint for the reducibility of metal oxide catalysts. However, although modeling of H2-TPR patterns has been extensively studied, little attention has been paid to the effect of particle-size distribution (PSD). The complexity of modeling H2-TPR patterns arises from the fact that the chemistry of metal oxide reduction depends on several factors, including particle size, nature of the support material and confinement within the porous structure, amongst others. In order to identify the kinetic reaction model governing the reduction of certain metal oxides and to explore the effect of PSD, pure metal oxides that only exhibited the particle size difference effect were used to model the H2-TPR patterns. Kinetic and thermodynamic data, which are very useful for characterizing heterogeneous catalysts, were obtained from this study. This work presents a simple procedure for modeling H2-TPR patterns of various metal oxides (i.e., CuO, Ag2O, and NiO) used as active phases in several reactions of environmental and energetic interest using several solid-state reaction kinetic models and considering their PSDs. The results obtained show that modeling the H2-TPR profiles provides information regarding the PSD of metal oxide catalysts that undergo a single-step reduction and only present the particle size difference effect.

Revisiting the scattering regime map based on transport scattering coefficient for dielectric particulate medium

The independent scattering assumption is frequently employed in radiative transfer, as it is applicable to numerous scientific and practical scenarios involving sparsely distributed scatterers. However, dependent scattering effects must be considered if the particle distribution is not sparse, which requires a relatively more rigorous analysis. A scattering regime map that summarizes the conditions where the independent scattering assumption can be used safely was established in the 1980s. The validity of this regime map and corresponding transition criteria has been questioned due to revealed inaccuracies in certain portions of the map based on the recent experimental studies. This study aims to reevaluate the regime map for dielectric particulate medium through numerical simulations utilizing dense medium radiative transfer theory relying on static structure factor for incorporating the effects of dependent scattering. The transport scattering coefficient, encompassing both the scattering coefficient and the asymmetry parameter, is employed as the metric of evaluation as it accounts for both the quantitative and directional behavior of the scattering. Besides, it also reflects the behavior of reflectance/transmittance closely, which is presented by comparing the regime maps based on transport scattering coefficient and reflectance. While the resulting modified regime map agrees mostly with the established map, it corrects the parts where discrepancies were observed so that the modified map is in agreement with all available data. Moreover, the effects of particle size distribution and material properties are also investigated and it was found that a regime map for lower relative refractive index miss-match between particle and medium produces a demarcation line that is more conservative.

Experimental and numerical study of the effect of particle size distribution on hydrocyclone classification

Classification by particle size using hydrocyclones is a fundamental step in various industries, yet the influence of material properties remains an area of limited understanding. This paper presents a comprehensive experimental and numerical investigation to illuminate the complex relationship between the feed particle size distribution (PSD) and the classification process. The feed PSD is characterised by two crucial parameters: the median size (d50f) and the distribution coefficient (σJ), derived from Johnson’s SB function. The results reveal non-monotonic variations in cut size and curve slope during physical tests where the two parameters are not separated. With one parameter held constant in numerical tests, an increase in d50f generally leads to a decrease in pressure drop but an increase in water split, while σJ exhibits an opposite trend. The interplay between the two parameters and their effects on cut size and cut sharpness is intricate, primarily determined by the characteristics of the flow field and the relative sizes of the cut size and d50f in the feed. These findings underscore the critical role of feed material properties in operating hydrocyclones for fine particle classification.

Effect of particle size distribution on the transmission efficiency of atomized water to the tracheal tube

Ultrasonic atomization is a widely used technology. As the atomization device, lead zirconate titanate (PZT) and lithium niobate (LN) are comparatively investigated through experimental and numerical schemes. However, knowledge on a profitable scheme by which to efficiently deliver the atomized particles into the tracheal tube remains unclear. In this study, the physical difference of the transmission efficiency of water particles atomized by PZT and LN devices was measured. The water particles atomized by PZT and LN were injected into a human airway model including a nasal cavity and bronchial tube. The distribution of the amount of transmitted particles deposited at each of the monitoring positions was then estimated using the results of image analysis of color intensity. As a result, the atomized particles of the PZT device, which produced larger particles than the LN device, were more strongly affected by inertia and tended to be deposited at the area closer to the entrance of the nasal cavity. In contrast, the particles produced by the LN device tended to be transmitted deeper into the trachea. The experimental results indicated that the particle size distribution of PZT and LN, which have quite different maximum sizes of particles, largely influences the spatial distribution characteristics of particle deposition along the airway from the nasal cavity to the trachea.

Effect of particle size distribution on aggregate structures of cubic hematite particles in quasi-2D system (without applied magnetic field)

We considered a dispersion composed of polydisperse cubic hematite particles in thermodynamic equilibrium, and conducted cluster-moving Monte Carlo (MC) simulations to investigate the internal structure of cubic particle aggregates in a quasi-2D system. The investigation focused on various factors, such as the strength of magnetic particle–particle interaction, the standard deviation of the particle size distribution, and the volumetric fraction of particles. In a polydisperse system with a small standard deviation, cubic particles tended to aggregate and form closely packed structures with almost perfect face-to-face configuration, as in the case of a monodisperse system. In a polydisperse system with a larger standard deviation, only large particles tended to aggregate and form closely packed clusters with an aligned face-to-face configuration, while small particles moved as single particles in the system, because the magnitude of the magnetic moments is proportional to the particle volume. The magnetic interactions between small particles are not sufficiently strong for the particles to come into contact. Therefore, an increase in the standard deviation leads to unstable face-to-face contact within closely packed clusters. In a polydisperse system with a larger standard deviation, an increase in the volumetric fraction promotes aggregation, but smaller particles preserve their individual status.

Study on Effect of Particle Size Distribution on Water-Retention Capacity of Coral Sand from Macro and Micro Perspective

The reclamation coral sand (CS) layer is the survival environment for island reef vegetation in the South China Sea. The root system within the CS bed draws water necessary for vegetation growth, implying that the water-retention capacity of CS plays a pivotal role in determining vegetation viability. Particle size distribution (PSD) significantly influences the water-retention capacity of geomaterials. This study examines the impact of PSD on the water-retention capacity of CS from both macro (soil–water characteristic curve, SWCC) and micro (pore water distribution) perspectives using the pressure plate test and nuclear magnetic resonance technique, and an F&X model was used to analyze the SWCC of CS. The findings indicated that the F&X model aptly describes the SWCC of CS with different PSDs. Both the air entry value and residual water content rise with an increased content of fine grains (d < 0.25 mm), suggesting that the presence of fine grains augments the water-retention capacity of CS. It is considered that a size range of d = 0.075–0.25 mm predominantly impacts the water-retention capacity of CS. The PSD primarily influences the water-retention capacity by affecting the pore size distribution of CS. The volume of small pores swells with the surge of fine-grain content, while the maximum pore size contracts with increasing fine-grain content. Limited pore connectivity in CS means macropores can retain water even under high suction, bolstering the water-retention capacity of CS. These findings offer theoretical guidance for selecting gradation parameters for the planting layer on island reefs.

Recycled PVC content and particle size distribution effects on morphological and mechanical properties of expanded PVC layer for floorcoverings

Recycled PVC content and particle size distribution effects on morphological and mechanical properties of expanded PVC layer for floorcoverings

Preparation and sound absorption performance of low‐carbon fly ash cenosphere plates

ABSTRACTA series of low‐carbon fly ash cenosphere plates was prepared using solid waste based cementitious material as binder through a simple process; meanwhile, effects of cenosphere's particle size and size distribution on microstructure and properties were investigated. In the range of 20–200 mesh, as particle size decreases, sound absorption performance decreases while strength improves. Appropriate particle grading can effectively improve the compressive strength, but it will lead to a significant decrease in sound absorption performance. Samples prepared from fly ash cenosphere with a particle size of 20–40 mesh show good sound absorption performance: when the cavity size is 0 mm, the maximum sound absorption coefficient is 0.64 and the average value is 0.36 in the range of 50–1 600 Hz; when the cavity size is 100 mm, sound absorption coefficient at 100 Hz is 0.47, the maximum sound absorption coefficient in the range of 50–1 600 Hz is 0.90, and the average value is 0.57 in the range of 100–500 Hz. The prepared low‐carbon fly ash cenosphere plates show excellent sound absorption performance at low‐frequency and are expected to have broad application prospects in low‐frequency noise reduction and absorption.

Effect of particle size distribution on the cryogenic mechanical properties of triple‐base propellants

AbstractFillers play a decisive role in the mechanical properties of polymer composites. In this paper, different particle sizes of nitroguanidine were obtained to regulate the internal filler structure of triple‐base propellants (TBP) to improve their mechanical response in different environments. A series of morphological and structural characterizations on nitroguanidine (NQ) particles were conducted using techniques. The results indicated that the obtained NQ particles maintained a high level of crystalline quality while preserving their molecular integrity. The mechanical properties of TBP were systematically evaluated under various loading conditions, including cryogenic tensile, compressive, and impact loads, as well as dynamic thermomechanical effects. Additionally, three‐point bending simulations were employed to elucidate the mechanical responses and damage mechanisms. Under axial tensile and compressive loads, reducing the particle size of NQ significantly enhanced the tensile and compressive strength. The maximum tensile strength and compressive strength can reach 344.62 MPa and 104.79 MPa. Moreover, the compressive failure mode transitioned from cracking to axial shrinkage. Conversely, when subjected to radial bending loads, TBP exhibited contrasting behavior, including a decrease in the glass transition temperature from 84.73°C to 76.93°C and a non‐monotonic trend in impact strength (initially increasing from 4.96 to 8.85 kJ/m2 and then decreasing to 2.27 kJ/m2). This study provides valuable insights into the mechanical performance of TBP, supporting the development of high‐energy, high‐strength TBP formulations.Highlights SEM analysis confirms the pronounced orientation effect of rod‐like NQ. The orientation and particle size of NQ decide TBP's radial impact resistance. Submicron NQ enhances the compression resistance property of TBP. Submicron NQ brings about a shift in the microscopic damage morphology of TBP.

High-Volume Mineral Admixtures Cement: The Effects of Particle Size Distribution

High-Volume Mineral Admixtures Cement: The Effects of Particle Size Distribution

Numerical Investigation of Wide Continuous Particle Size Distribution Effect on the Liquid–Solid Fluidized System

Numerical Investigation of Wide Continuous Particle Size Distribution Effect on the Liquid–Solid Fluidized System

Cohesion and shear strength of compacted lunar and Martian regolith simulants

Shear strength and cohesion of granular materials are important geotechnical properties that play a crucial role in the stability and behavior of lunar and Martian regolith, as well as their terrestrial analog materials. To characterize and predict shear strength and cohesion for future space missions, it is also important to understand the effects of particle size distribution and density on these fundamental geotechnical properties. Generalized equations have been established using empirical data from direct shear measurements of lunar and Martian regolith simulants to quantify the effects of particle size distribution and density on cohesion and shear strength. Preliminary results are also presented highlighting the effects of atmospheric absorbed water on shear strength and cohesion when conducting experiments in atmospheric conditions on Earth. The results of this study show that cohesion increases exponentially with bulk density, while the exponential growth constant is also dependent on particle size distribution. The presence of absorbed atmospheric water can also produce non-monotonic effects on the shear strength of regolith, and it's influence on shear strength varies based on sample density for Earth-based experiments and applications. Together, these results highlight the importance of particle size distribution, bulk density, and atmospheric water content on the shear strength and cohesion of lunar and Martian simulants. This study also establishes generalized equations for predictive, testing, and modeling efforts for future space missions.

Simplified DEM-Based Modelling and Simulation of the Track Ballast

This study proposes a rational method for modelling ballast in tracks based on the discrete element method (DEM) approach. To simulate a ballast consisting of a group of gravels, it is essential to use the discrete element method. The ballast comprises randomly arranged gravels of unspecified shapes, and requires multiple steps and a separate house code for implementing the ballast. In this study, a simplified ballast analysis model using the parallel bond method (PBM) is proposed and verified through comparison with design standards. Additionally, case studies are conducted to investigate the effect of particle size distribution and micromechanical parameters on the simulation results.

Study on reactivity characteristic of TDA droplet group with gaseous phosgene for preparing TDI

Toluene diisocyanate stands as a pivotal chemical, predominantly synthesized through the phosgenation reaction between toluene diamine and phosgene. To address the inherent limitations of existing phosgenation methods, we pioneered a novel phosgenation reaction based on flash atomization and confirmed its feasibility with preliminary theoretical calculations. This manuscript delves deeper into the superiority of this method and refines its reaction parameters. By integrating the discrete phase model with the Eulerian model, we studied the reaction dynamics of droplet sprays, exploring the effects of spray velocity, droplet size, phosgene temperature, and particle size distribution on the reaction. Our results highlight that, with a mean droplet diameter of 70 μm and a spray velocity of 40 m/s, an impressive reaction yield of 97.4 % can be achieved. This research enriches our understanding of the gas–liquid two-phase phosgenation method, setting the stage for its future exploration and potential applications in Toluene diisocyanate and other isocyanate industry.

Design method of high transport performance biochar-cement based materials based on particle size distribution and permeation probability calculation model

Cement-based materials are the most widely used and largest quantity of engineering materials. Enhancing carbon fixation efficiency and reducing carbon emissions in cement-based materials is an active method of coping with climate change, which has important environmental and social benefits. The amount of carbon dioxide transported into the cement-based material represents the maximum carbon fixation capacity. Enhancing the carbon transport performance of cement-based materials is the material guarantee and basic premise for improving their carbon fixation levels. Considering the impact of particle connections on the maximum cluster, a permeation probability calculation model of porous media system was established, providing the changing rule of the permeation probability with the mathematical expectation of the Poisson distribution, which was verified to be reasonable through experimental studies. The experimental results showed that under the same cement-based conditions, the water transport properties of biochar cement-based materials increased as the mathematical expectation increased. The carbon dioxide transport properties were influenced by the surface area of the biochar particles and exhibited a trend of first decreasing and then increasing with an increase in the mathematical expectation. When the water-cement ratio decreased, the differences in the microstructure of cement-based materials with different biochar particle size distributions increased, the change rate of permeation probability therefore was more sensitive, resulting that the differential effects of different particle size distributions on the transport properties were amplified, and the influence of the particle size distribution of biochar on the transport properties of cement-based materials was more significant.