Mechanical synthesis of lithium titanate hydrate (LHTO: Li1.81H0.19Ti2O5·xH2O) in liquid phase was investigated using a bead mill. LHTO has layered crystal structure which leads to form thin plate particles. As starting materials, lithium hydroxide which was dissolved in water and titanium dioxide nanoparticles were used. As bead media, 0.3, 0.5 and 1 mm diameter of zirconia balls were employed. At least some amount of LHTO was formed at each bead size condition. In cases of 0.3 and 0.5 mm beads, crystallization of LHTO looked not to proceed after some hours. After 5 hours, the most crystallized LHTO was synthesized at 1 mm beads. Some of observed particles showed thin plate shape but the greater part of particles were fine particles in the obtained powder. It was supposed that synthesized LHTO particles were broken faster than crystals of LHTO grew up since small bead media performed high grinding ability.
Solid dispersion is a common useful technique which makes a crystal drug into amorphous. It improves the dissolution of the insoluble drug by using a rise in solubility, to increase the gastrointestinal tract absorption. In this study, dissolution characteristics of solid dispersion were improved by adding mannitol to the solid dispersion. The effect of mannitol addition to the solid dispersion formulation including PVP-K30 on the dissolution property was investigated. A large difference was observed between two manufacturing methods, a solvent distillation by an evaporator and a spray drying. The different effect of the mannitol addition appeared in the influence of the particle size of solid dispersion particles, although the composition of solid dispersion manufactured by both methods was the same.
Transition metal dichalcogenides are interesting materials with the features of the layered structure and high electrical conductivity. It is known that the metal dichalcogenides represented by molybdenum disulfide (MoS2) have two structures, a semiconductor 2H type, and a metal 1T type, and the physicochemical properties of different phase compositions are dramatically changed. MoS2 has excellent flexibility, good adsorption ability, and reactivity at room temperature, offering a potential possibility for wearable sensor device development. To increase the number of MoS2 active sites and realize the surface and phase engineering of 1T/2H-MoS2, a series of surface modification methods, such as ethylene glycol intercalation under solvothermal treatment, oxygen plasma treatment, and elements substitution, were carried out. Different kinds of gasses have been successfully detected by using MoS2 as a sensor material at room temperature, which increases its possibility to be one of the suitable candidates for novel and wearable sensor devices material.
Metalate nanosheets are synthesized by bottom-up process in aqueous solutions. The acid-base reactions between the hydroxides of bulky cations, e.g., N(CH3)4OH and N(C4H9)4OH, and the metal hydroxides produced by hydrolyzing metal species yield layered metalates with interlayer bulky cations. The layered metalates are swollen and exfoliated in aqueous sols, producing metalate nanosheets. Herein, the bottom-up synthesis of metalate nanosheets are described from three viewpoints: (1) aqueous solution chemistry relevant to the dissolution of metal hydroxides in water, (2) the synthesis of metal oxide powders using metalate nanosheets, and (3) the comparison with the conventional synthesis method of metalate nanosheets.