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.