The manufacture of materials using slurry-based processes, such as the electrodes of Li secondary batteries and fuel cells, can be made more productive by increasing the concentration of the slurry. Shear thickening, which is a particular issue for such highly concentrated slurries for the electrodes of Li secondary batteries, is derived from collisions between particles, it is important to control the size, size distribution, and concentration of the particles, as well as the solvent viscosity. Furthermore, the electrostatic interaction between the particles has a direct impact on shear thickening, and the concentration of salt in the slurry and the particle surface charge are also important characteristics. Since cracks in catalyst layers of a fuel cell affect performance and durability, it is important to obtain the factors that control crack formation. Crack behavior can be controlled by ionomer adsorption into the Pt/carbon in catalyst ink. A well-dispersed catalyst ink produces a homogeneous Pt/carbon and ionomer distribution in the catalyst layers with high fracture toughness, while catalyst inks with a network of agglomerates produce dense aggregates with small primary pores that generate high drying stress.

In this paper, we would like to discuss on electro-conductive inks and pastes including metal nanoparticles and/or fine particles as the conductive materials. This paper introduces the particle preparation strategies, dispersion method and investigation of the detailed structure during sintering. In particular, low-temperature sintering of copper fine particle pastes is focused. The cutting edge points of the conductive inks and pastes, that is, oxidation prevention, dispersing methods, and the use of MODs will be discussed.

Recently, synthetic innovations have allowed the fabrication of atomically precise gold nanoclusters（ Au NCs）. These Au NCs show potential for green energy and medical applications. The present article primarily focuses on ligand protected Au NCs and their application. The review comprises four sections:（ i） fluorescence of Au NCs,（ ii） fluorescence sensing using Au NC,（ iii） therapy and antibacterial applications, and（ iv） catalysis.

In wet granulation processes, a particle adhesion mediated by a liquid bridge is one of the quite important phenomena. In an actual process, the liquid bridge shows dynamic motion due to motion of the particles. Therefore, understanding of a particle-particle adhesion by such a dynamic liquid bridge is an important issue. We have conducted a direct numerical simulation of the particle-particle adhesion by the dynamic pendular liquid bridge. In this review, our recent studies are presented. Firstly, a direct numerical simulation method is briefly explained. Secondly, verification and validation of the direct numerical simulation are presented. Finally, our work, where influence of the wettability of particles on the particle-particle adhesion of colliding particle through droplet was analyzed, is presented.

In colloidal suspensions, electrostatic interactions, hydrodynamic interactions, and their dynamic coupling are of crucial importance both in statics and kinetics of structure formation and rheology, leading to the emergence of various functions of charged soft matter in technological applications and biological cells. From the theoretical and computational viewpoints, however, it has been very challenging to take electrostatic and hydrodynamic interactions into account because both are long-ranged many-body interactions. Another difficulty originates from the fact that the number of charges on colloidal surfaces is determined by chemical equilibrium, and thus, affected by the presence of other colloids or charged surface. Fluid Particle Dynamics （FPD） method is a powerful method to deal with these problems in a physically transparent manner. We here review the concept of the FPD method incorporating the self-organization of colloidal charges - charge regulation. We describe the details of the theoretical formulation to treat long-range electrostatic and hydrodynamic interaction. We also show two computational results where charge regulation becomes relevant as examples. Our method is applicable to more complex problems of charged soft matter systems.

This paper describes the definition and concept of dispersibility and dispersion stability and explains that it is important to clarify the differences between these definition/concept to use. Ultrasonic attenuation spectroscopy and sedimentation analysis method are introduced as characterization methods applicable to highly concentrated dispersions in order to evaluate the extent of aggregation/dispersion state without dilution. As choice of the method properly depends on what and why will be measured, characteristics of each methods and examples of the measurement for practical dispersions were shown.

This article introduces the interpretation of critical coagulation concentration（ CCC） on the basis of DLVO theory and zeta potential. We begin with the overview of DLVO theory with emphasizing how we get its analytical expression, and then mention electrophoresis and zeta potential as a tool to characterize the charging of colloidal particles. Further, we describe recent interpretations of CCC using DLVO theory. That is, while DLVO theory does not consider ion specific effects, DLVO theory with effective charge density from zeta potential can rationalize ion-species dependent CCC. Also, the Schulze-Hardy empirical rule, which suggests CCC is strongly related to counter-ion valence, can be explained by the combination of DLVO theory for low electric potential and effective surface charge density. Well-known assumption that the surface potential is extremely high is probably incorrect. This means that the measurement of zeta potential at different solution conditions and the development of theoretical model predicting zeta potential are crucially important. At last, we mention the inverse Schulze-Hardy rule is confirmed experimentally and theoretically.

The stability of particle suspensions, which is important in various industrial processes, is generally dominated by the interaction forces between the particles. Understanding the interaction forces between surfaces in liquids is therefore fundamentally important to evaluate and control how particulate matters, including two phase fluids such as emulsions and bubbles, disperse and aggregate in various systems. The invention of the surface force apparatus（ SFA） enabled the direct measurement of interaction forces between surfaces in liquids with molecular level resolution has led to remarkable progress in understanding surface forces in detail and the application of atomic force microscopy（ AFM） to force measurement has further extended the possibility of force measurements to a broad field of research. This review provides an overview of developments in the investigating of interaction forces between surfaces using SFA and AFM. The properties of various interaction forces are described in detail, particularly focusing on how the nanoscopic structures of various interfaces, including the adsorption structures of solvent and solute molecules and their assemblies to them, play an important role in the interaction forces, between particles.