Atmospheric‐pressure nonthermal plasma was used to synthesize ammonia from nitrogen and hydrogen over ruthenium catalysts. Formation of NH3 in a N2‐H2 mixture altered the plasma characteristics due to the low ionization potential of NH3 (10.15 eV). The optimum gas ratio was found at N2:H2 = 4:1 by volume (i.e., N2‐rich conditions). When plasma was operated at a temperature below 250 °C, the NH3 concentration increased linearly with increasing specific input energy (SIE). For the Ru(2)‐Mg(5)/γ‐Al2O3 catalyst at 250 °C, pulse energization was four times more efficient than the AC energization case. The presence of RuO2 was found to be beneficial for the NH3 synthesis via plasma‐catalysis. The addition of a small amount of O2 was found to be effective for the in situ regeneration of the deactivated catalyst. The effect of metal promoters was in the order of Mg > K > Cs > no promoter.

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A pressure transmitting medium named Daphne 7474, which solidifies at P(s)=3.7 GPa at room temperature, is presented. The value of P(s) increases almost linearly with temperature up to 6.7 GPa at 100 degrees C. The high pressure realized by a medium at the liquid state allows a higher limit of pressurization, which assures an ideal hydrostatic pressure. We show a volume change against pressure, pressure reduction from room to liquid helium temperature in a clamped piston cylinder cell, pressure distribution and its standard deviation in a diamond anvil cell, and infrared properties, which might be useful for experimental applications.

Optical reflectivity experiments have been conducted on single crystals of the Kondo insulator YbB12 in order to obtain its optical conductivity, σ(ω). Upon cooling below 70 K, a strong supression of σ(ω) is seen in the far-infrared region, indicating the opening of an energy gap of ∼ 25 meV. This gap development is coincident with a rapid decrease in the magnetic susceptibility, which shows that the gap opening has significant influence on magnetic properties. A narrow, asymmetric peak is observed at ∼ 40 meV in σ(ω), which is attributed to optical transitions between the Yb 4fderived states across the gap. In addition, a broad peak is observed at ∼ 0.25 eV. This peak is attributed to transitions between Yb 4f -derived states and p-d band, and is reminiscent of similar peaks previously observed for rare-earth hexaborides.