A Japanese concept of considerations for evaluation of dental materials for tooth bleaching.

Recent advances in bleaching technology, such as bleaching ingredients, have accelerated the development of tooth whitening materials to change the color of natural teeth toward a lighter or whiter shade. Some bleaching materials are used for patients in combination with auxiliary medical devices to activate the bleaching materials by a light or heat source. Bleaching ingredients can be a poisonous and deleterious substance. Some bleaching materials are used in dental offices and the others at home. In clinical development of bleaching materials, appropriate evaluation of safety and efficacy is required according to the intended use. For appropriate and swift approval of the emerging bleaching materials, guideline on evaluation of dental whitening materials was discussed in a commissioned project by the Ministry of Health, Labour and Welfare of Japan for FY2021. Here, we summarize the current principles of the premarketing evaluation of the safety and efficacy.

Study on X-ray enhancement in Laser-Compton scattering for auger therapy.

PURPOSE: Monochromatic hard X-rays with high brightness are desired for medical applications including Auger therapy. One can generate such X-rays through laser-Compton scattering (LCS) by allowing photons from a compact laser system to interact with electrons accelerated by a compact electron accelerator. In this paper, after a brief description of laser-Compton X-ray sources, a scheme called crab crossing to enhance the X-ray intensity is proposed. The effect of crab crossing is evaluated, and we report our dedicated laser system for the crab crossing LCS research. MATERIALS AND METHODS: The luminosity enhancement factor by crab crossing is evaluated. For the electron beam, a rf deflector will be used to generate a tilted electron beam. For the laser system, chirped pulsed amplification is adopted. Yb-doped optical fibers and a Yb:YAG thin-disk is used for the laser gain media. RESULTS: The luminosity enhancement factor by crab crossing is expected to be 3.8 when the crossing angle is 45 degrees. 10mJ pulse energy was achieved by thin-disk regenerative amplifier. The pulse duration after the pulse compressor was about 1.5 ps. CONCLUSION: We are going to demonstrate the LCS X-ray enhancement by crab crossing of electron beam and laser pulse. The expected enhancement factor is 3.8. We have successfully finished the laser development and the proof-of-principle experiment will be conducted soon.

Perceptual adaptation during a balancing task in the seated posture and its theoretical model.

This paper proposes a theoretical model of the control and perception mechanism in human balance. Human balance perception is evaluated by the subjective upright posture, the posture at which a person does not feel he/she is at an incline. Our balance experiments in the seated posture showed that the subjective upright posture changed after the balancing task where the participants needed to incline to maintain their balance. This paper aimed to explain this adaptive phenomenon by reproducing the experimental results using computer simulations. Hypothesizing that "humans gradually come to recognize the posture they need to take to maintain their balance as being upright," an adaptation rule for subjective upright posture is defined, so that it approaches the averaged posture in the period of the balancing task. For the balance control, center of pressure feedback is adopted. As a result, the similar changes in subjective upright posture are simulated with a two-link model with a base link, implying that our hypothesis is one possible explanation on the mechanism for human balance control and perception.

Modeling Approach for An Aortic Dissection with Endovascular Stenting.

Repair of dissected aorta requires remodeling the structure of the media. Modeling approaches specific to endovascular stenting for aortic dissection have been reported. We created a goat model of descending thoracic aortic dissection and reproduced its morphological characteristics in a mock circulatory system. The purpose of this study was to examine a newly developed aortic stent which was capable of installing to the aortic dissected lesion for biomedical hemodynamics point of view. In this study, we examined the changes in hemodynamics of dissected lesions and the amelioration by endovascular stent intervention. Firstly, we performed animal experiments with the dissected aorta and examined the effects of stenting on volumetric changes in the false lumen. Secondly, we made several types of 3-D stereolithographic dissected aortic models with silicone rubber membrane between the false and the true lumens. Then, the hemodynamic characteristics in each model were evaluated in the pulsatile flow conditions in a mock circulatory system. These modelling approaches enabled the quantitative examination of post-therapeutic effects of stenting followed by elucidating of hemodynamic changes in the vicinity of stents, which may follow the management of clinical amelioration of interventional treatment with aortic stenting.Clinical Relevance- This study represents a modelling approach of the dissected aorta for endovascular intervention using stenting followed by the examination of false lumen volumetric changes resulting in the deterioration of pressure increase in diseased lesions.

Self-organization of an organic-inorganic hybrid nanomushroom by a simple synthetic route at the organic/water interface.

A new strategy for the synthesis of a mushroom-like aggregate, based on repeated sequences of a 3D gold nanoparticle-conducting polymer-gold nanoparticle arrangement, by a single-step process at the organic/water interface has been described.