Discrete Element Method (DEM) was proposed by Cundall and Strack (1979) and gained traction in the field of powder engineering during the late 1980s. In the 1990s, various applications of DEM were conducted in the powder technology field, and the capability of DEM for predicting powder behavior was acknowledged. In the 2000s and 2010s, advancements in computing technology and the availability of general-purpose software led to the widespread adoption of numerical simulation as a prevalent tool in industrial applications. The authors have been engaged in discrete particle modeling of gas–solid two-phase flows and the development of DEM–CFD models for the numerical analysis of both dense gas–solid two-phase flows and gas–liquid–solid three-phase flows. Thus, this paper aims to provide a comprehensive description of the pioneering development of discrete particle models and simulations conducted by the authors.

Dose accuracy and precision for pulmonary drug delivery have been core elements of therapy for asthma for 70 years. As the technology has developed, its application has spread to various diseases. For many inhaled products, solid-state chemistry, the nature of the drug particles, and their relationship to other particles in the formulation underpin success in disease treatment. Methods of manufacturing yield unique particle systems whose properties support the range of doses required to treat diseases with low- and high-potency drugs requiring high and low doses, respectively. To ensure the quality of these particulate products, which correlates with safety and efficacy, comprehensive characterization of their physicochemical properties and aerosol performance is required. The delivered dose and aerodynamic particle size distribution are key characteristics related to lung exposure required in clinical efficacy trials for non-communicable, genetic, environmental, and communicable (i.e., infectious) diseases. The breadth of inhaled therapy has increased significantly since the introduction of the initial products in the last century. The desire to treat genetic diseases, such as cystic fibrosis, and the emergence of new approaches to lung therapy during the COVID-19 pandemic are opening up new opportunities in inhaled biologicals that are anticipated to lead to future developments.

As an extension of Particle Technology (PT), “nanoparticle technology (NPT)” has emerged as a transformative research endeavor in many countries, including Thailand. NPT has delivered significant strides in research, development, and applications. This review paper explores the advancements and contributions of NPT within Thailand’s scientific community and industrial sectors by analyzing original technical publications on Thailand’s contributions during 2008–2024. Also, a brief mention of the establishment of the Center of Excellence in Particle Technology (CEPT) at Chulalongkorn University and the National Nanotechnology Center (NANOTEC) under the National Science and Technology Development Agency (NSTDA) is given. The key NPT research issues, namely, synthesis methods, characterization techniques, and applications across various disciplines, including medicine, agriculture, and the environment, are selectively reviewed. The paper also discusses collaborative efforts, challenges, and future directions, highlighting Thailand’s roles in the global landscape.

The control of adhesion and aggregation behaviour in gases, liquids, and solids is important for the application of inorganic nano- and fine particles in various fields, such as functional materials and devices, pharmaceuticals, cosmetics, and pigments. We have developed original methods for the characterisation of interfacial molecular- and nanometre-scale structures and interactions between particles and substrate materials. The surface molecular-structure design by an organic surfactant, commonly called a “ligand,” was investigated with different molecular structures for nanoparticle-dispersion stability control in various organic solvents and polymer solid materials. First, we introduce various approaches for controlling the interfacial molecular structure of nanoparticles to disperse nanoparticles in various liquids. Next, aggregation- and adhesion-behaviour characterisation methods, such as colloid probe atomic force microscopy and the control of fine powders and microcapsules in the ceramic and pharmaceutical fields, are reviewed. Finally, the characterisation and control of the adhesion behaviour of fine ash particles at high temperatures in energy generation and environmental systems are investigated. Original characterisation devices and a model of an ash-particle preparation method from pure silica were developed by adding small amounts of elements, such as alkali metals and phosphates, to analyse the increase mechanism of the ash-adhesion force at high temperatures. Based on the results of the analysis, the adhesion behaviour can be controlled by the addition of various materials.

Dry powder coating, characterised by the blending of poorly flowing powders with finer coating powders to optimise flowability, represents a sophisticated and evolving approach to powder processing. The optimisation of this method involves precise formulation, carefully combining powders with different particle properties to achieve a desirable blend aimed at enhancing the flow characteristics during the application process. Over the last decade, this field has witnessed increasing activity, focusing on key mixing parameters, such as mixer type and mixing power, as well as understanding the influence of constituent powder characteristics, including size ratio, density, and cohesion. Various techniques have been used to assess the flowability improvement or quantify the degree of coating. This review aims to provide a comprehensive exploration of the literature on powder coating research, highlighting its significance in both academic research and industrial applications. This paper discusses current coating analysis techniques using state-of-the-art equipment and reviews recent findings, particularly the nascent attempts to establish regime maps for dry powder coating.

Polymer selective laser sintering (SLS) is an additive manufacturing technology that involves the melting of a selected area of particles on the powder bed. A 3D component is then printed using layer-by-layer sintering of the powder bed. SLS is considered one of the most promising technologies applicable to a variety of applications, particularly for manufacturing customized design products with high geometric complexity, such as patient-specific designed implants, surgical tools. Currently, only a small number of polymers are available that are suitable for SLS due to the complex multiple physical phenomena involved. Therefore, it is critical to develop new materials in order to fully realize the potential of SLS technology for manufacturing value-added customized products. For a given material, the quality of powder spreading in SLS plays a key role in printing performance and is a precondition for new material development. The aim of this review is to (1) present flowability characterization methods suitable for SLS, (2) examine the influence of powder properties and flowability on laser–material interaction and the quality of the final part, and (3) discuss the methods adopted in the literature to improve the quality of powder spreading.

Ultrafine bubbles (bulk nanobubbles), small bubbles with a diameter of less than 1 μm, have attracted academic and industrial attention because of their numerous advantages, including their chemical-free nature and extraordinarily long lifetime. The long lifetime is related to the much higher Brownian motion velocity compared to buoyancy. The reason why ultrafine bubbles can endure under stable conditions is still unclear, even though their inside is highly pressured. They have several characteristics, such as pH-dependent surface charge and reduced friction. They are also closely related to ultrasound. Ultrafine bubbles are generated and removed by selecting the ultrasonic frequency. Reaction and separation using ultrasonic cavitation and atomization, respectively, are enhanced by ultrafine bubbles. They can produce hollow nanoparticles, enhance adsorption on activated carbon, and clean solid surfaces. This review discusses the fundamental and ultrasonic characteristics of ultrafine bubbles and their application in particle-related technology, encompassing fine particle synthesis, adsorption, desorption, extraction, cleaning, and prevention of fouling.

The Janssen equation is a widely used method for calculating pressures in bulk storage structures. This review explores the historical legacy of Janssen’s equation and its applications in both planar and three-dimensional structures. Our focus is on the limitations of the original formulation of Janssen, extensions made to avoid these deficiencies, and alternative models that have been developed. The motivation behind these modifications is to improve the representation of shear stress within a grain bin in both the horizontal and vertical directions. Modifications to Janssen’s basic assumptions include the vertical-to-horizontal stress ratio (k), the coefficient of friction between the wall and the stored bulk material (μ), internal angle of friction (φ), and bulk density (ρ). We also discuss recent developments in pressure theories, which have provided new insights into pressure fields in bulk storage bins. These modern approaches include the continuum elastic theory and microscopic theory. Finally, we discuss recent developments in pressure theories which provide new insights into the storage of bulk solids. Overall, this review provides a comprehensive overview of the Janssen equation and its historical development, limitations, and extensions, as well as recent advancements in pressure theory that offer a more accurate representation of pressure fields in bulk storage structures.

Chemical mechanical polishing (CMP) is a process that uses mechanical abrasive particles and chemical interaction in slurry to remove materials from the surface of films. With advancements in semiconductor device technology applying various materials and structures, SiO₂ (silica) nanoparticles are the most chosen abrasives in CMP slurries. Therefore, understanding and developing silica nanoparticles are crucial for achieving CMP performance, such as removal rates, selectivity, decreasing defects, and high uniformity and flatness. However, despite the abundance of reviews on silica nanoparticles, there is a notable gap in the literature addressing their role as abrasives in CMP slurries. This review offers an in-depth exploration of silica nanoparticle synthesis and modification methods detailing their impact on nanoparticle characteristics and CMP performance. Further, we also address the unique properties of silica nanoparticles, such as hardness, size distribution, and surface properties, and the significant contribution of silica nanoparticles to CMP results. This review is expected to interest researchers and practitioners in semiconductor manufacturing and materials science.

Many processes involve solid bowl centrifuges as a solid–liquid separation step, typically used for clarification, thickening, classification, degritting, mechanical dewatering, and screening. In order to operate solid bowl centrifuges safely, with minimum resource consumption and reduced setup times, modeling and optimization are necessary steps. This is a challenge due to the complex process behavior, which can be overcome by developing advanced physical models and process analysis. This review provides an overview of solid bowl centrifuge applications, their modeling, and addresses future optimization potentials through digital tools. The impact of dispersed phase properties such as particle size, shape, surface roughness, structure, composition, and continuous liquid phase is the reason for the lack of generally applicable models. Laboratory-scale batch sedimentation centrifuges are used to predict material behavior and develop material functions describing separation-related properties such as sedimentation, sediment build-up and sediment transport. The combination of material functions and modeling allows accurate simulation of solid bowl centrifuges from laboratory to industrial scale. Since models usually do not cover all influencing variables, there are often deviations between predictions and the real process behavior. Gray-box modeling and on-line or in-situ process analytics are tools to improve centrifuge operation.

Lithium-ion batteries (LIBs) provide the largest source of electrical energy storage today. This paper covers the use of comminution processes and, thus, crushers and mills for particle breakage and dispersing, as well as classifiers for particle separation within the process chain, from the raw material to the final lithium battery cell and its recycling at end of life. First of all, the raw materials for the active material production have to be produced either by processing primary raw materials, or by recycling the spent lithium batteries. The end-of-life battery cells have to be shredded, the materials separated and then milled in order to achieve the so-called black mass, which provides a secondary material source with very valuable components. Using these materials for the synthesis of the cathode active materials, milling has to be applied in different stages. The natural graphite, increasingly used as anode material, has to be designed in mills and classifiers for achieving targeted properties. Nanosized silicon is produced by nanomilling using stirred media mills as a primary option. Conductive additives for LIBs, like carbon black, have to be dispersed in a solvent with machines like planetary mixers, extruders or stirred media mills. In the future, mechanochemical synthesis of solid electrolytes will especially require additional application of comminution processes.

It is well known that the functionality of inorganic materials strongly depends on the chemical composition, morphology, particle size, crystal facet, etc., which are strongly influenced by the synthesis process. The precise control of the synthesis process is expected to lead to the discovery of new functionality and improvement of the functionality of materials. For example, in a high-temperature solid-phase reaction, it is difficult to control the morphology of nanocrystals. On the other hand, synthesizing functional materials using solution processes, such as hydrothermal and solvothermal reactions, makes it possible to control the morphology and particle size precisely. Usually, the solution process is strongly related to the dissolution reprecipitation mechanism. Therefore, the material composition can be strictly controlled and is suitable for forming fine particles with high crystallinity. In this review paper, the role of the solvent in the solution process, its effect on particle size and morphology of the transition metal oxide, and the related functional improvement will be focused. Furthermore, the direct formation of functional thin films by the solution process and the morphology control by non-oxide materials by the topotactic reaction will also be introduced.

It is well established that the critical performance metrics for aerosol products are aerodynamic particle size distribution (APSD) and delivered dose uniformity (DDU). In broad terms, these performance characteristics dictate the efficiency and reproducibility with which an aerosol is administered clinically. However, these properties alone do not support in-vitro, in-vivo correlations. There have been numerous publications attempting to more directly link product performance testing to physiological relevance or further to draw direct correlations of relevance to bioequivalence testing for the development of generic products. While these novel methods have been employed in product development activity, their suitability for compendial testing has yet to be established. This paper explores the potential to establish biologically relevant compendial standards for dry powder inhaler products while maintaining accuracy and reproducibility of data collected to support the quality and performance of the product.

Higher performance is constantly required in rare earth permanent magnets, which are an indispensable component of the motors of electric vehicles. When producing sintered magnets, advanced structural control is necessary in the powder metallurgy process in order to achieve high performance. Especially in recent years, it has become important to develop processes for Sm-Fe-N magnets and metastable phase magnets as next-generation magnets to replace the Nd-Fe-B magnets. Because the crystal grain refinement of sintered magnets is most effective for improving coercivity, production methods for raw powders have evolved from the traditional pulverization to chemical synthesis approaches, and as a result, a submicron-sized Sm-Fe-N powder with huge coercivity has been developed. State-of-the-art physical synthesis methods have also been applied successfully to the synthesis of nanopowders. Since control of the grain boundary is very effective in Nd-Fe-B magnets, this approach has also been evolved to Sm-Fe-N magnets by nano coating. On the other hand, since technologies for crystalline orientation control and high-density sintering are indispensable for improvement of remanence, new low-thermal load consolidation techniques such as spark plasma sintering are being developed for Sm-Fe-N magnets and metastable phase magnets in order to overcome the inherent low thermal stability of these materials.

Spray drying is gaining traction in the pharmaceutical industry as one of the processing methods of choice for the manufacture of solid dosage forms intended for pulmonary, oral, and parenteral delivery. This process is particularly advantageous because of its ability to produce engineered particles with improved efficacy and stability by combining active pharmaceutical ingredients or biologics with appropriate excipients. Moreover, due to its high throughput, continuous operation, and ability to produce thermostable solid powders, spray drying can be a manufacturing method of choice in the production of drugs and other formulations, including vaccines, for global distribution. Formulation design based on a mechanistic understanding of the different phenomena that occur during the spray drying of powders is complicated and can therefore make the use of available particle formation models difficult for the practitioner. This review aims to provide step-by-step guidance accompanied by critical background information for the successful formulation design of spray-dried microparticles. These include discussion of the tools needed to estimate the surface concentration of each solute during droplet drying, their times and modes of solidification, and the amount of glass stabilizers and shell formers required to produce stable and dispersible powders.

Li-ion batteries with “nickel” as the main material or the highest ratio material on the cathode or anode electrode have attracted considerable attention. Nickel has high strength and corrosion resistance. Nickel has also been utilized successfully as the cathode and anode materials. The specific capacity and energy and power density of the material increased with increasing nickel content. However, several problems have limited the use of nickel-based Li-ion batteries. Problems such as cation mixing, the properties of nickel, and highly Ni-rich compounds leading to side reactions, influence the electrochemical performance of Li-ion batteries. The morphology is another factor affecting the electrochemical performance. Further studies will be needed to synthesize materials with the desired morphology and determine how the morphology affects the electrochemical performance. In a morphological perspective, extensive morphological adjustments are a pathway to a long and stable life cycle. In this light, nickel-based electrodes are manufactured continuously and will always be considered for next-generation secondary energy storage. The morphology of nickel-based active materials is one of the main factors determining the high-performance of Li-ion batteries.

While the formulation of pharmaceuticals as liquids is common practice, powders are associated with enhanced stability, avoidance of the cold chain, lower dosing requirements, and more convenient administration. These are particularly critical for proteins, as they are expensive and complicated to manufacture. Powders also have improved aerosol properties for pulmonary delivery. Conventional techniques for formulating powders include spray-drying, shelf freeze-drying, spray freeze-drying, and spray freezing into liquid, but they produce powders with poor aerosol performance and/or activity due to suboptimal powder properties. Thin-film freezing (TFF) is a new cryogenic technique that can engineer highly porous, brittle, powder matrices with excellent aerosol performance properties and stability. Herein, we describe TFF in comparison to other cryogenic techniques. Physical properties of TFF powders such as morphology, moisture sorption, stability, solubility, and dissolution, as well as aerosol properties are discussed. In addition, factors that significantly affect the physical and aerosol properties of dry powders prepared by TFF, such as solids content, drug loading, solvent system, excipient, and dry powder delivery device, are analyzed. Finally, we provide evidence supporting the applicability of using TFF to prepare dry powder formulations of protein-based pharmaceuticals, enabling their cold chain-free storage as well as efficient pulmonary delivery.

Particle breakage occurs in comminution machines and, inadvertently, in other process equipment during handling as well as in geotechnical applications. For nearly a century, researchers have developed mathematical expressions to describe single-particle breakage having different levels of complexity and abilities to represent it. The work presents and analyses critically a breakage model that has been found to be suitable to describe breakage of brittle materials in association to the discrete element method, either embedded in it as part of particle replacement schemes or coupled to it in microscale population balance models. The energy-based model accounts for variability and size-dependency of fracture energy of particles, weakening when particles are stressed below this value, as well as energy and size-dependent fragment size distributions when particles are stressed beyond it, discriminating between surface and body breakage. The work then further validates the model on the basis of extensive data from impact load cell and drop weight tests. Finally, a discussion of challenges associated to fitting its parameters and on applications is presented.

Microspheres composed of poly (lactic-co-glycolic acid) (PLGA) were formed in liquid droplets using the electrospray technique. The structure of the microspheres was controlled by changing the electric voltage of the electrospray. PLGA microspheres with porous structures and micro-sized nanocomposite particles comprising PLGA nanosphere aggregates were formed at 5.0–7.0 kV and 2.5–3.5 kV, respectively. The structural change was related to the extent of evaporation of the solvent from the droplets during their flight. When the evaporation was completed in the relatively small droplets, the microspheres with porous structures were formed in the droplets. To study the mechanism, we observed the effects of the electric voltage of the electrospray, PLGA concentration, flight distance of the droplets, and molecular weight of PLGA on the structure of the PLGA particles. The novelty of this study is the analysis of the size and structure of the PLGA microparticles, which were controlled by the electrospray technique. Therefore, this research has important implications for the structural design and preparation of nanocomposite particles.

A workflow for developing a multidimensional, linear correlation between the process conditions during fluidized bed spray granulation and the surface morphology of the resulting granules is presented. Spray coating experiments with Cellets^®500 particles and sodium benzoate solution were performed in a lab-scale fluidized bed varying liquid spray rate, fluidization air flow rate, fluidization air temperature, spray air temperature and spray atomization pressure. To characterize the surface structure, the surface roughness of the coated particles was quantified using confocal laser-scanning microscopy. The roughness was correlated to the process conditions, and the resulting correlation was rigorously analyzed for the importance and co-linearities of the individual process parameters using a principal component analysis. The surface roughness is strongly dependent on the spray rate of the coating solution, the fluidization air temperature and the atomization pressure at the nozzle. In general, wet process conditions and large droplets with a low initial velocity favor the formation of particles with a rough surface structure, while dry conditions and fine droplets with a high velocity result in granules with a smooth and compact coating layer.