Quantum cascade lasers with Y2O3 insulation layer operating at 8.1 µm.

SiO2 is a commonly used insulation layer for QCLs but has high absorption peak around 8 to 10 µm. Instead of SiO2, we used Y2O3 as an insulation layer for DC-QCL and successfully demonstrated lasing operation at the wavelength around 8.1 µm. We also showed 2D numerical analysis on the absorption coefficient of our DC-QCL structure with various parameters such as insulating materials, waveguide width, and mesa angle.

Alternative Patterning Process for Realization of Large-Area, Full-Color, Active Quantum Dot Display.

Although various colloidal quantum dot (QD) coating and patterning techniques have been developed to meet the demands in optoelectronic applications over the past years, each of the previously demonstrated methods has one or more limitations and trade-offs in forming multicolor, high-resolution, or large-area patterns of QDs. In this study, we present an alternative QD patterning technique using conventional photolithography combined with charge-assisted layer-by-layer (LbL) assembly to solve the trade-offs of the traditional patterning processes. From our demonstrations, we show repeatable QD patterning process that allows multicolor QD patterns in both large-area and microscale. Also, we show that the QD patterns are robust against additional photolithography processes and that the thickness of the QD patterns can be controlled at each position. To validate that this process can be applied to actual device applications as an active material, we have fabricated inverted, differently colored, active QD light-emitting device (QD-LED) on a pixelated substrate, which achieved maximum electroluminescence intensity of 23 770 cd/m2, and discussed the results. From our findings, we believe that our process provides a solution to achieving both high-resolution and large-scale QD pattern applicable to not only display, but also to practical photonic device research and development.

Human embryonic stem cell-derived neural precursor transplants attenuate apomorphine-induced rotational behavior in rats with unilateral quinolinic acid lesions.

To test the efficacy of human embryonic stem cell (hESC)-derived neural precursors in an experimental model of Huntington's disease (HD), we differentiated hESC into nestin-positive neural precursors by co-culturing with PA6 stromal cells, and subsequently transplanted them into the striatum of quinolinic acid (QA)-induced HD model. The transplanted animals exhibited a behavioral recovery in the apomorphine-induced rotation test for 3 weeks after transplantation. The transplanted hESC-derived neural precursors were found in both cortex and striatum. They also exhibited some evidence of neuronal differentiation. At the time of examination, no tumor was detected. These results strongly suggest that hESC-derived neural precursors can lead to a behavioral recovery, as well as neuronal differentiation, in the pre-clinical model of HD.