Nagoya Municipal Industrial Research Institute

Titanium dioxide (TiO2) nanoparticles have been used as ultraviolet light scattering agents in sunscreen cosmetics. However, they tend to self-aggregate due to their high surface energies and strong interparticle attraction in water. In this research, we focused on liquid surface plasma (LSP), and studied the water dispersion technology of fine-particle TiO2. The plasma formed is considered to generate shock waves and species such as O radicals, which have high oxidation potential, around the liquid surface. The LSP treatment enabled preparation of the aqueous dispersions with 10% (wt) TiO2 nanoparticles that have approximately 100 nm particle size and long-term stability. In addition, from the chemical analyses of the dispersions, Al compounds derived from the underwater Al electrode were formed on the TiO2 surface. It was clear that TiO2 nanoparticles had high positive charge under pH neutral condition due to Al compounds on the surface, so that the dispersions were stabilized by electrostatic repulsion between the particles. Furthermore, from the X-ray absorption fine structure (XAFS) measurements, it was found that the chemical state and molecular structure of Ti were not altered by the LSP treatment, and amorphous aluminum hydroxide (Al(OH)3) was detected on the surface. These findings suggest that the TiO2 aqueous dispersion obtained by the LSP treatment can be safely applied to cosmetics. Finally, a composite powder (PLD-TiB), which is BaSO4 covered with TiO2, was obtained by electrostatic combination in aqueous dispersion. From the SEM image, it was observed that the BaSO4 surface was uniformly coated with TiO2. Due to the uniform coating without aggregation, PLD-TiB had a great UV protecting effect and a smooth feeling on the skin.

Our objective is to consider how the geometric stiffness of the flexible absorbing structure caused by the introduction of initial tension influences each deformation of the structure. A flexible structure is defined as a structure consisting of a discontinuous compressive member and a continuous tensile member that maintains a self-equilibrium state due to the introduction of an initial tension in the tensile member. A numerical simulation with modal analysis applied to the mathematical model corresponding to the experimental model is carried out to experimentally investigate deformations affected by the geometric stiffness of the flexible structure and deformations not affected by the stiffness. Experiments are conducted to simulate each mode of deformation obtained from the numerical calculations, and comparison and discussion of the obtained results with the actual measurements and the numerical analysis results are reported.

Infantile wheezing and eczema are associated with the subsequent onset of asthma and other atopic diseases. However, there are no large population-based surveys on infantile allergic symptoms in Japan. The objective of the study was to determine the prevalence of wheezing and asthma in infants in Nagoya, Japan. This population-based cross-sectional study was performed in the metropolitan city of Nagoya, Japan. We surveyed parents to ascertain the prevalence of wheezing and eczema in infants who attended group health checkups at 3, 18, and 36 months of age. Their parents completed modified questionnaires from the International Study of Asthma and Allergies in Childhood. More than 90% of the approximately 40,000 children in each study group living in the target area were included in the survey. The prevalence of wheezing was 8%, 17%, and 13% at 3, 18, and 36 months, respectively, and was characterized by birth season. The prevalence of eczema was 24%, 30%, and 31%, at 3, 18, and 36 months, respectively. Participants born in autumn and winter had a higher incidence of eczema in each age group. Three-quarters of the children had a parental history of allergic conditions. Parental allergic diseases and male gender are risk factors for wheezing and eczema in children. This survey had a high response rate and covered almost the entire population of the target age groups in a large city. We believe that the results of this study, therefore, provide a much higher level of confidence regarding the prevalence of allergies in infants in Japan than that in previous studies with limited cohorts.

There is demand for higher mechanical properties of glass fiber-reinforced plastics (GFRP) in line with the expansion of applications. However, as the fiber length shortens during processing, the strength of GFRP decreases. Hence, it is necessary to develop an efficient and accurate method for implementing fiber length measurement, which is an important phase in improving the processing. In this study, we examined the fiber length measurement method from three different points of view : the number of fibers to be measured, the appropriate size of the test piece, and the fiber length distribution, which may be biased due to the dilution of dispersing liquid. The number of fibers for accurate measurement depends on the fiber length distribution. In addition, it was found that the size of the test piece was determined by the fiber length. Moreover, the dilution of the fiber dispersing liquid did not affect the distribution of the fiber length to be tested.

Effective stress-true plastic strain curves of aluminum alloy 2024-T351 were obtained by an optimization method using the experiment analysis of digital image correlation method and the simulation of finite element method. Notched round bar specimens with a radius of 16 mm were used for tensile tests. The effects of strain rate on flow stress after stress correction were examined. The yield stress was almost the same or showed a small positive strain rate sensitivity. The flow stresses at a true strain of 0.20 clearly showed negative to positive strain rate sensitivity.

Three dimensional numerical analysis is utilized for thermal design of electronic devices. In this calculation, power consumption of electronic component are needed for input values, and they have an important consequence for prediction accuracy. But, it is often the case that the values are imprecision, because it is not well defined to measure or calculate the values at the moment. We developed an estimation method using temperature measurements and thermal analysis. We obtained a parameter about thermal of electronic components in advance. Next, the temperature of each electronic components was measured. Then, the power consumption can be obtained using them. This estimation method is effective because it does not require special equipment.

Equivalent stress-equivalent plastic strain curves of 2024 aluminum alloy thin plates, 1.6 mm in thickness, were obtained by an optimization method using the digital image correlation method and the finite element method. Notched plate specimens with a radius of 30 mm were used for quasi-static tensile tests. The equivalent stress-equivalent plastic strain curve of piecewise linear model was determined by an optimization method. The correction factor of optimized equivalent flow stresses and initial true stresses was proposed.