Although a large number of aerosol droplets are known to be produced from the human larynx during vocalizations, it remains unclear how vocal fold oscillations are involved in the droplet production. In this study, we synthesized vocalizations using two types of silicone vocal fold models and investigated the effects of these model configurations on the droplet production mechanisms by measuring the particle concentrations when artificial mucus was injected into the artificial larynx. One model, which oscillates with complete glottal closure, produced louder sounds with droplets, whose diameter ranged primarily from 0.3 to 2μm. In contrast, the other model, which oscillates without vocal fold collision, produced smaller sounds with droplets having larger diameters. Additional observations using the laser sheets and high-speed imaging demonstrated that the liquid films were formed just above the vocal folds when a constant jet flow was generated in the model which does not exhibit complete glottal closure. These results describe how different oscillation characteristics of the vocal folds may cause differences in droplet concentration.

We carried out ex vivo and in vivo experiments to explore the functional role of the ventricular folds in sound production in macaques. In the ex vivo experiments, 29 recordings out of 67 showed that the ventricular folds co-oscillated with the vocal folds. Transitions from normal vocal fold oscillations to vocal-ventricular fold co-oscillations as well as chaotic irregular oscillations were also observed. The in vivo experiments indicated that the vocal-ventricular fold co-oscillations were also observed in two macaque individuals. In both ex vivo and in vivo experiments, the vocal-ventricular fold co-oscillations significantly lowered the fundamental frequency. A mathematical model revealed that the lowering of the fundamental frequency was caused by a low oscillation frequency inherent in the ventricular folds, which entrained the vocal folds to their low-frequency oscillations. From a physiological standpoint, the macaques may utilize the ventricular fold oscillations more frequently than humans. The advantages as well as disadvantages of using the ventricular folds as an additional vocal repertory are discussed.

The homogeneous formation of high-mobility oxide semiconductor thin films over large areas at low temperatures was accomplished by optimizing both the film formation process and the low-temperature post-processing via plasma annealing. Increasing the substrate-to-target distance ( D ST ) and the applied target voltage was found to produce more uniform deposition. The results of the field-effect mobility distributions of IGZO TFTs processed using plasma annealing were founded that plasma annealing generated essentially uniform distributions with μ FE values in the range of 32–35 cm 2 V −1 s −1 .

パルス DC スパッタリングは、低いデューティ比で平均電力を抑えながらスパッタリングを行 うことが可能であり,金属ターゲット表面に酸化物や窒化物薄膜が形成される事が原因で発生す るアーキングを抑制するなどの放電安定性にも優れているため、近年工業分野で注目を集めてい る。しかしながら通常のパルス DC スパッタリングは、ターゲット近傍のみにプラズマが局在す るため、窒化物や酸化物の機能性薄膜形成における反応性制御を行うことは困難である。そこで 本研究では、パルス DC スパッタリングに誘導結合プラズマを重畳したスパッタシステムを構成 し、誘導結合プラズマを独立に制御し、スパッタ粒子の供給束と薄膜の結晶性や組成に影響する 反応性を独立に制御可能な、誘導結合プラズマ支援パルス DC スパッタリングによる製膜を行っ ている。ターゲットに印加する電圧のパルス放電周波数や放電 On/Off 時間の比(デューティ比) を変化させることにより、窒化アルミニウムの製膜速度および膜質に与える影響を調べた。結果 の一例として、Alターゲットを用いて製膜を行った際の放電周波数 10kHzでデューティ比を 20% から 70%まで変化させた際の断面 SEM写真を Fig. 1示す。デューティ比を増加させると製膜速度 は上昇するが、Fig.1 に示すように柱状構造から粒状構造に膜構造が変化した。SEM-EDX の結果 からデューティ比が増加すると膜中の N密度が減少する結果が得られており、デューティ比の増 加によりターゲットから供給されるアルミニウム増加するため、十分に窒化されず膜構造に影響 を与えていることが示唆される。詳細は講演にて。