Field effect transistors (FETs) made of thin flake single crystals isolated from layered materials have attracted growing interest since the success of graphene. Here, we report the fabrication of an electric double layer transistor (EDLT, a FET gated by ionic liquids) using a thin flake of MoS(2), a member of the transition metal dichalcogenides, an archetypal layered material. The EDLT of the thin flake MoS(2) unambiguously displayed ambipolar operation, in contrast to its commonly known bulk property as an n-type semiconductor. High-performance transistor operation characterized by a large "ON" state conductivity in the order of ~mS and a high on/off ratio >10(2) was realized for both hole and electron transport. Hall effect measurements revealed mobility of 44 and 86 cm(2) V(-1) s(-1) for electron and hole, respectively. The hole mobility is twice the value of the electron mobility, and the density of accumulated carrier reached 1 × 10(14) cm(-2), which is 1 order of magnitude larger than conventional FETs with solid dielectrics. The high-density carriers of both holes and electrons can create metallic transport in the MoS(2) channel. The present result is not only important for device applications with new functionalities, but the method itself would also act as a protocol to study this class of material for a broader scope of possibilities in accessing their unexplored properties.

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Little is known regarding the incidence of the shoulder instability in Japan. The aim of this study was to evaluate the incidence of traumatic shoulder instability among Japanese military cadets. A prospective cohort study was performed to capture all traumatic shoulder instability events between 2009 and 2012 among cadets in a military educational academy of the Japan Self Defense Forces. The total number of cadets in the cohort was 5,402 (average age 20.6 years). The incidence of instability events, including dislocation or subluxation, was calculated. Chronicity, demographics of participants, mechanism of injury, and athletic events were also evaluated. The incidence of traumatic dislocation was 4.1/1,000 person-years and that of subluxation was 6.1/1,000 person-years. The incidence of primary dislocation or subluxation was 5.4/1,000 person-years and that of recurrent dislocation or subluxation was 4.7/1,000 person-years. Of first dislocations or subluxations, 92% occurred during sports activities, including after-school sports activities, military training, and gym classes. In conclusion, the overall incidence of shoulder instability events among Japanese military cadets was 10.3/1,000 person-years, and was extremely high. Most shoulder instability events occurred during sports activities, and a program to prevent such injuries during sports activities is necessary for young participants.

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