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Streptococcus mutans form oral biofilms (BFs) and cause dental caries. Roasted green tea (RGT) is prepared by roasting the tea plant, and RGT-specific polyphenols are produced during the roasting process. Catechins, polyphenols in green tea, have BF inhibitory activity against S. mutans; therefore, RGT-specific polyphenols are also expected to have this activity. However, there are few reports on the structural and functional properties of RGT. This study aimed to investigate the inhibitory activity of RGT against S. mutans BF formation and to investigate the active compounds. RGT extract fractionation and BF inhibitory assay were performed. Strong activity was confirmed in the RGT fractions that had medium-high hydrophobicity, were rich in phenolic hydroxyl groups, and lacked catechins. A peak comprising compounds with molecular weights of 918 (mw918) and 1050 (mw1050) was purified from the fraction. Since BF inhibitory activity was confirmed for this peak, these compounds were considered to be part of the active ingredients. The mw918 polyphenol was detected only in RGT and it was thought to be produced during the roasting process. The results of this research will serve as a basis for the future application of RGT as a safe and effective anti-caries agent.

In recent years, it has become possible to experience sports in the virtual reality (VR) space. Although many haptic displays in the VR environment currently use vibrators as the mainstream, the vibrators’ presentation is not suitable to express ball-receiving in the VR sports experience. Therefore, we have developed a novel haptic display that reproduces an impulsive force by instantaneously applying traction to the palm using a string and wearable brake system. This paper proposes a method to present various reaction forces by dynamic control of the braking system and report the quantitative evaluation of the device’s physical and psychological usability.

β-Lactams are important structural motifs because of their ubiquity in natural products and pharmaceuticals. We report herein a Cu-catalyzed intramolecular oxidative C(sp3 )-H amidation for the synthesis of β-lactams using tBuOOtBu. This method is based on Kharasch-Sosnovsky amidation and does not require prefunctionalization of C(sp3 )-H bonds or the installation of a directing group, thereby allowing for the straightforward synthesis of β-lactams. Our intramolecular functionalization protocol can be extended to diverse benzylic C(sp3 )-H bonds and shows excellent functional-group tolerance.

Tactile sensation consists of sensory information at a contact status between human and the other environment. The contact status draws some physical phenomena. The tactile sensor has to record the sensory information, so the sensor should record these physical phenomena. The physical phenomena of the contact point are listed as follows; deformation, stress, temperature, and time variation of these information. When human touch some environment the human finger will be deformed according to the pressed force and the reactive stress from the environment. The deformation and the stress are linked together and occur according to the Young's modulus and the Poisson's ratio of materials of the finger and the environment. If the materials can be assumed to be the total elastic body, the deformation and the stress can be linked by the linear elastic theory. Because there exists no total elastic body, the link between the deformation and the stress is a little complex. The complexity is enhanced when the contact state is changed according to time. For example, the human moves his finger toward the environment or touch a vibratory environment, the environment may return the damper or mass property with the change of movement speed or acceleration. The most characteristic example is a dilatants phenomenon. A dilatants material is one in which viscosity increases with the rate of shear. As a simple environment model, there exists such an impedance model

In the field of tactile displays, electrostatic force displays have been developed for presenting tactile stimulation on a screen. However, with the conventional electrostatic force displays, the user cannot feel the stimulation without rubbing on the display. In this paper, to solve this problem, we propose a new method to present a tactile sensation without moving a finger by creating a small space between an electrode and an insulating surface. Moreover, we evaluate the perceived threshold of the proposed display through the experiment.

Nowadays, touchscreens have been used worldwide. However, most of them lack realistic haptic feedback. Several haptic feedback devices employ one-dimensional vibration only. We aim at a novel rendering method for direction-controlled 2-dimensional vibration display to present texture information. This paper proposed a rendering method of texture information that enables lateral-force-based 2-dimensional vibration in the X and Y-axis. Moreover, we proposed combining AKAZE image feature information of the textures to improve the fidelity for larger periodic textures. We held experiments to evaluate the fidelity of the proposed method. The result shows that the proposed method has higher fidelity in presenting randomized textures and large periodic textures than the conventional method.