Carbon hollow particles (CHPs) have a lot of excellent properties such as a high specific surface area, large pore volume, and the presence of nanovoids, therefore they are applied to catalyst carriers and Li-ion batteries. However, a conventional method, hard templating method, has many problems. In this study, we developed a new method to synthesis CHPs improving thermal resistance of hollow particles (HPs) made of polymer by Friedel-Crafts hyper-cross-linking and Flame resisting treatment. This method does not require any templates which need to be removed and avoids using harmful materials such as hydrofluoric acid.
Particle wettability is an important property to design the manufacturing process and evaluate the product performance in powder and pharmaceutical technologies. The liquid penetration method is commonly used to evaluate the particle wettability. However, because the capillary pressure appearing in the particle bed is calculated with the characteristic capillary diameter based on the fluid motion through the particle bed, the method overestimates the contact angle. In this study, we simulated the liquid penetration into ordered particle layer, demonstrating that the characteristic diameters based on the fluid motion cannot estimate the capillary pressure correctly. Furthermore, we proposed two new characteristic diameters which were defined for the narrowest flow channel in the powder layer. The proposed diameters reasonably agreed with simulation results, indicating that the proposed characteristic capillary diameters can reasonably estimate capillary pressure.
The behavior of biodegradable poly lactic-co-glycolic acid (PLGA) nanoparticles (NPs) toward plant cells was investigated using confocal laser microscopy when exposed to leaves and roots of Arabidopsis thaliana. As a result, when the leaves were exposed to the PLGA NP suspension by applying pressure, the suspension penetrated into the leaves through the stomata, and the NPs were taken into the mesophyll cells. In contrast, PLGA NPs were taken into the cells of root tip and root hair with thin cell wall. These experimental results suggest that the PLGA NPs are suitable for delivery of useful substances into plant cells.
Pulsed laser melting in liquid (PLML) is a fabrication technique of submicrometer-sized crystalline spherical particles. Suspended aggregates of raw nanometer-sized particles are irradiated with a pulsed laser and then immediately molten droplets form due to a laser energy absorption of the raw aggregates. The formed droplets with spherical shape are immediately cooled and submicrometer-sized spherical particles are obtained. Unique submicrometer-sized crystalline spherical particles obtained with PLML are expected to have prominent properties in optical and magnetic applications. However, low mass productivity is a common problem in laser processing, and therefore a research development for spherical particle mass production by PLML is also necessary. In this report, we developed flow and batch apparatuses designed for mass production of submicrometer spherical particles by PLML technique and investigate parameter effects on successive particle fabrication by PLML for mass production. The results clearly indicate that following three factors have to be optimized for continuous synthesis of spherical particles: (1) efficient transport of target particles to irradiation space, (2) irradiation with appropriate number of pulses, and (3) quick replacement of irradiated particles in irradiation space with unirradiated particles during pulse interval.
Atmospheric-pressure micro-plasma jet (AP-μPJ), which is generated in a discharge tube of about 1 mm diameter and spouted out in the atmosphere, enables us to simply perform material processing in the atmosphere because of its excellent operability. Author has been studying the application of the AP-μPJ to synthesis of nanoparticles, and developed the following method: A metal wire is etched with plasma in a discharge tube, the resultant metal vapor is condensed to form NPs, and the NPs are jetted out and collected in the atmosphere. The features, equipment, details of NP synthesis process, gold NP synthesis and effective application of this method are introduced in this review.
In various fields, assessment of 3D characteristics (e.g., shape and size distribution) of discrete elements (e.g., particles) is required. Generally, however, 2D instead of 3D assessment is conducted due to practical limitations (e.g., time, cost, and measurement technology). In this study, then, experimental validation was conducted for a 2D-3D conversion method, developed in 2018, which estimates multiple 3D parameters based on 2D counterparts, using X-ray computed tomography analysis of silica sand. Six 3D parameters (volume, surface area, long-axis length, sphericity, long/middle and long/short axis ratio) were successfully estimated based on five measured 2D parameters (sectional area, perimeter, long-axis length, circularity, and long/short axis ratio).
To fully utilize intrinsic properties of carbon nanotubes (CNT) for the industrial application, preservation of the quality is of importance through dispersion processes in matrices. We demonstrated a 104-fold enhanced electrical conductivity of CNT rubber composite keeping the CNT quality by the predispersion of CNT powder in the viscous rubber base compound. Furthermore we found that higher viscosity solvents can more efficiently unravel CNT powders with slighter decreases of the CNT quality. Our method can refrain from long, heavy, conventional dispersions, and be widely applied to CNT industries.