Fundamental dissolution behavior of liquid silk (LS) gel taken out from the fully grown larva of Bombyx mori silkworm into water, and the influence of complex formations between fibroin and sericin fractions, were investigated. WAXD measurements of the “sea-island”-structured as-cast gel films revealed,after annealing, that the fibroin-rich “island”portion formed a stable silk 1 structure while the “sea”portion has been transformed from the amorphous into a silk 2 crystal structure at room temperature without any external shear force. For the fibroin phase, however, a very long relaxation time was required to obtain the silk 2 modification. We have studied the influence of the interaction between fibroin and sericin on the crystal modification directly in the lyophilized silk gland of the fully grown larva of Bombyx mori. In the posterior silk gland, the fibroin formed a silk 1 structure according to the polymorphism property of fibroin. In the middle silk gland where sericin P fraction is to be secreted, fibroin showed silk 2 crystal diffraction. Following the secretion of sericin P fraction, the sericin M fraction has become secreted indicated by definite silk 1 crystal diffraction. However, silk 2 crystal diffraction remained almost unchanged, which means that sericin M fraction has a potential to regulate the crystal transformation of fibroin. Furthermore, influence of the modulation of spinning process or the addition of metal ions into a LS aqueous solution in flow state on the formation of fiber structure was investigated.

TDK is developing a wireless power transfer technology for electric vehicles (EV) that is based on two coils: one built into roads, parking spaces, or garages and the other fitted to the underbody of the car. One of these coils is the power transmission coil, and the other is the receiving coil. The receiving coil receives the magnetic field generated by the power transmission coil. Furthermore, the rectifier rectifies the alternating current to direct current. A coil case with magnetic and conductive properties produces an eddy current and decreases the power efficiency. Therefore, non-magnetic and non-conductive materials must be adopted in the design of the coil case. Furthermore, the coil case must protect the coil, ferrite cores, and the electronic component array. According to the Underwriters Laboratories Inc. (UL) standard, a vehicle overdrive test must be performed on the power transmission coil such that even if a vehicle rides on the power transmission coil case, it should not be damaged. In addition, a prototype of the power transmission coil case made of glassfiber-reinforced plastic was created. During the glass-fiber-reinforced plastic molding process, the glass fiber bundle slipped and air gaps were formed. We decided to consider the scale of three patterns: micro, macro, and mesoscale. After considering the three scales, the experimental results and calculated results matched with high accuracy.

The density of cellulose nanofiber (CNF) sheets is strongly related to their physical properties for various applications. We investigated the effects of restraint drying on the density of CNF sheets. Furthermore, the density of the sheet was measured before and after cyclic wetting and drying. The CNF suspension was filtrated with a membrane filter under reduced pressure to prepare a CNF wet sheet. Hotpress drying could produce the visually flattest CNF sheet among the “hot-press drying”, “restraint drying”,and “unrestraint drying”processes. The density of the CNF sheet prepared at room temperature was higher than that prepared at 105 ̊C. The density of the CNF sheet prepared at 105 ̊C also increased with cyclic wetting and drying.