While novel technologies developed in academia are applied to dentistry, they often become medical devices. Homedweicavl erd, emviceany. Mreesedaicarchl edrs evhiceavs ae lirett le subkjecnowlet to dreggeu olatiof then s puroncdeessr ththea Pt hgaormes ainceto utibcrianl gainndg Mtheed picarodl uDect vtoice ths eAc mt, arkanedt naes w a products are reviewed by the Pharmaceuticals and Medical Devices Agency (PMDA), but there is often little knowledge about how they are evaluated. In addition, there are specific regulations regarding dental medical devices. There is a regulatory authorities. It is important for academic researchers to understand pharmaceutical regulations and necessary evaluations in advance, and this understanding will lead to faster development and industry-academia co-creation. for the development of dental medical devices in academia, based on my experience. Hiroki HIHARA discrepancy between the evaluations considered by the researchers and the necessary evaluations considered by the Therefore, I describe the outlines of the pharmaceutical regulations and clinical evaluations that are considered essential for the development of dental medical devices in academia, based on my experience.

In vivo impact test assuming human-robot interaction has been conducted using live porcine and drop weight impact tester in order to obtain bruise injury criteria. As a results, bleeding was found to occur at the part of adipose tissue in the case of low velocity and high energy conditions. In contrast, bleeding was found to occur at the part of conducted on simple model consist of skin and soft tissue in order to clarify the occurrence mechanism of soft tissue bruise injury caused by impact assuming human-robot interaction. FE model imitated subcutaneous structure of porcine skin used as impact test. Analytical conditions were assumed to the experimental condition that bleeding occurs at the parts of adipose tissue and muscle. As a results, the part of taking maximum first principal strain is good agreement with the bleeding point obtained by experiments. Moreover, it was found that subcutaneous hemorrhage was strongly affected by impact loading conditions than subcutaneous tissue structure.

The viscosity of the extracellular matrix (ECM) surrounding the cell is closely related to cell function. To elucidate the mechanical behavior of cells, it is important to understand the viscosity response of the cell and the surrounding ECM. The viscosity of the ECM has been treated as the macroscopic modulus of elasticity of the collagen gel. However, since the ECM is a complex aggregate of collagen fibers, it is highly likely that the coarseness, density, orientation, etc. of the fibers differ microscopically. Therefore, it is necessary to measure the microscopic spatially varying elastic behavior. Therefore, the purpose of this study is to investigate the spatially heterogeneous viscosity inside gels. We have developed a magnetic field type spatial viscosity distribution measurement system in which magnetic particles are dispersed in a gel and displacement can be induced forcibly by an external magnetic field. As a result, we used digital image correlation analysis to a collagen gel and measured the forced displacement field of magnetic particles dispersed in the collagen gel by an external magnetic field. This revealed that a spatial distribution was generated in the viscosity. Therefore, we succeeded in obtaining not only the macro viscosity, but also the micro viscosity distribution.

To evaluate in vivo contact behavior and relative sliding movement between the femoral and tibial components using a 2-D to 3-D image matching technique, we developed a method to determine the contact points in a time series from the amount of interference between the tibial and femoral component models, and evaluated the relative contact distance from the contact points in consecutive time frames. This method was applied to three types of knee prostheses with different geometries, and the relative contact travel distance and contact depth distributions between the femoral component and tibial insert were obtained during the weight-bearing knee flexion. At the same time, the relative motion of the femoral component to the tibial insert was evaluated by measuring the change in the position of the approximate sphere center of internal and external condyles as kinematics evaluation. The contact travel distance and contact depth distributions and the relative motion of the femoral component were considered to be influenced by the insert geometry.

In this study, we examined the psychological stress experienced by occupants in a vehicle cabin owing to seat vibrations. First, we measured the seat and each occupant's vibration during an idle state and assessed the temporal change of the occupants' center of gravity, as well as their electroencephalography (EEG) results. The vibration of the occupant and that of the seat with the occupant differed, and the transfer path of the vibration from the seat to the occupant varied depending on the physical characteristics of the occupant. We propose a hypothesis for the relationship between the psychological stress caused by seat vibration and the characteristics of the temporal change in the center of gravity. This hypothesis states that the occupant experiences psychological stress owing to seat vibration in the idle state when the power spectral density (PSD) of the temporal change in the occupant's center of gravity has a distinct peak at approximately 2 Hz. This hypothesis was tested with 20 subjects (participants), confirming its validity. It was inferred that occupants whose temporal change in the center of gravity was periodic tended to experience psychological stress owing to seat vibration.

Propagation of shock waves generated by explosions is one of the important research topics in safety engineering. Thus, shock wave attenuation using filters has been investigated. In this study, the flow in the vicinity of a filter installed in air and water was visualized by the Schlieren method using a shock tube with a square section. In air, the shock wave was weakened by the filter. However, the filter was greatly deformed by the flow behind the shock wave. In water, no shock wave propagated behind the filter. Slight deformation was noted on the filter in water due to the flow that passed through the filter. Moreover, the flow speed behind the filter was suppressed as the number of cells in the filter was increased.

Reducing spatter, i.e., melt droplets flown out of the melt pool, is one of the critical issues when laser cutting is employed as a machining tool for radioactive wastes because the ejected droplets can lead to radioactive contamination with potential human exposure. The spattering phenomena are complicated processes that involve multiple physical phenomena, causing difficulty in the determination of laser parameters to minimize the amount of spatter. Here we observe the spatter ejected from 316L stainless steel plates using a high-speed camera and apply a machine learning technique to these captured images on the basis of three distinctive behaviors appeared at specific time intervals of the process of spattering phenomena: (I) a vapor, (II) a liquid film and breakup into droplets, and (III) a liquid capillary. The numerical model established through the machine learning technique predicts the spattering phenomena with an accuracy of 89% and can be used to determine the laser power and beam diameter that reduce the spatter eruption during laser irradiation.