We realized room-temperature lasing of blue and green GaN-based vertical-cavity surface-emitting lasers (VCSELs), for the first time, by current injection. The blue GaN-based VCSEL had a threshold current of 1.5 mA and a threshold voltage of 3.3 V under continuous-wave operation. Its maximum output power was 0.70 mW and its laser emission wavelength was 451 nm. The green GaN-based VCSEL had a threshold current of 22 mA and a threshold voltage of 6.3 V under pulsed current operation. Its maximum output power was estimated to be over 0.80 mW and the laser emission wavelength was 503 nm.

The absolute densities of H atoms produced in catalytic chemical vapor deposition (Cat-CVD or hot-wire CVD) processes were determined by employing two-photon laser-induced fluorescence and vacuum ultraviolet absorption techniques. The H-atom density in the gas phase increases exponentially with increases in the catalyzer temperature in the presence of pure H2. When the catalyzer temperature was 2200 K, the absolute density in the presence of 5.6 Pa of H2 (150 sccm in flow rate) was as high as 1.5×1014 cm−3 at a point 10 cm from the catalyzer. This density is one or two orders of magnitude higher than those observed in typical plasma-enhanced chemical vapor-deposition processes. The H-atom density decreases sharply with the addition of SiH4. When 0.1 Pa of SiH4 was added, the steady-state density decreased to 7×1012 cm−3. This sharp decrease can primarily be ascribed to the loss processes on chamber walls.

No abstract

The catalytic decomposition processes of NH 3 on heated W surfaces were examined by employing laser spectroscopic techniques. H atoms and NH 2 radicals were identified as primary decomposition products on the catalyzer surfaces. The effective enthalpies for the production of these species were both determined to be 150 kJ/mol. NH radicals were also identified, but the production of this species is ascribed to secondary processes. N atoms are minor products in both the primary and secondary processes. The absolute density measurements show that the decomposition efficiency of NH 3 is comparable to that of H 2 . The steady-state densities of NH 3 and the stable products, H 2 and N 2 , were also measured by mass spectrometry. When the catalyzer temperature is over 2000 K, the H 2 density is comparable to that of residual NH 3 . H atoms are produced not only by the direct decomposition of NH 3 but also by the decomposition of H 2 .

Background: A host receptor has not yet been identified for glycerol monomycolate (GroMM), an immunostimulatory lipid of mycobacteria. Results: GroMM recognition occurred in cell transfectants expressing human, but not mouse Mincle. Human Mincle transgenic mice acquired the ability to respond to GroMM. Conclusion: GroMM is a ligand for human Mincle. Significance: The molecular basis underlying the innate immune recognition of GroMM has been elucidated.