We numerically investigate the stability of a cylindrical column composed of wet granular materials under gravity using the discrete element method. When the column height exceeds a critical value H_c, the column collapses under its own weight. From the phase diagram for stability, we demonstrate that the critical height depends on the surface tension γ. Applying the Mohr-Coulomb yield criterion, we theoretically determine the critical height H_c, which is subsequently validated through numerical simulations.

In an era of ever-mounting hurdles related to energy, resources, the environment, and labor costs, innovative ideas are urgently needed to overcome the difficulties of materials production. Mechanochemistry could be a gamechanger in this regard. This review reassesses selected topics in mechanical activation and mechanochemical processes. The discussion begins with the fundamental principles and mechanisms of change in the electronic states of polyatomic systems due to forced deformation, and followed by the cutting-edge, environmentally benign technology. The latter includes scaling up organic syntheses and preparing new functional metal-organic frameworks and non-calcining building materials. These topics may not always align with the interests of some readers of this journal. However, revising established concepts in conventional materials genres and fusing knowledge from different disciplines will provide the powder engineering community with new insights and trigger breakthroughs.

Size segregation phenomena in granular media subjected to vibration are reviewed. Various explanatory mechanisms proposed in the literature are presented, including convection, void-filling, arching effect, condensation, granular temperature gradients, and entropic-like forces. While each mechanism provides valuable insights, these explanations remain qualitatively limited in scope and applicability. Studies on quasi-two-dimensional (2D) setups are also discussed, which, despite their simplicity, exhibit various structural formations including crystallization, segregation patterns, and quasicrystals. Recent findings on reducing segregation by increasing the volume fraction of small particles are described. Granular segregation remains an active research area with fundamental mechanisms still unestablished, despite its practical importance across various industries including food processing, pharmaceuticals, construction materials, and cosmetics.

Particle shapes of raw, granular materials affect their bulk properties, but 2D measurements can introduce stereological errors. We developed a method to estimate 3D shapes from 2D images without pre-training. First, 3D shapes reflecting measured 2D characteristics are generated using a Fourier shape descriptor. Next, spherical harmonic-based principal component analysis refines them so their 2D projections match observed shapes. Accuracy is fivefold better than using Fourier descriptors alone. This method requires no pre-training, making it applicable to any particles. As a demonstration, we used it to estimate 3D shapes of Martian rocks from Perseverance rover images.

Dry particle composite processing is a key technique for developing advanced materials. By applying mechanical energy, fine particles can be fixed onto larger ones, improving handling, reducing adhesion, or enabling coating and energy-efficient ceramic fabrication. This method is applicable across diverse fields, including toner flow improvement, lithium-ion batteries, pharmaceuticals, and sintering-free ceramics. Dry processing equipment, such as Mechanofusion systems, enables scalable production without solvents. Case studies demonstrate enhanced performance in electrical conductivity, drug dissolution, and mechanical strength, highlighting the versatility and industrial relevance of dry particle composite technologies.