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Singlet oxygen is a reactive oxygen species undesired in living cells but a rare and valuable reagent in chemical synthesis. We present a fluorescence spectroscopic analysis of the singlet‐oxygen formation activity of commercial peroxidases and novel peroxygenases. Singlet‐oxygen sensor green (SOSG) is used as fluorogenic singlet oxygen trap. Establishing a kinetic model for the reaction cascade to the fluorescent SOSG endoperoxide permits a kinetic analysis of enzymatic singlet‐oxygen formation. All peroxidases and peroxygenases show singlet‐oxygen formation. No singlet oxygen activity could be found for any catalase under investigation. Substrate inhibition is observed for all reactive enzymes. The commercial dye‐decolorizing peroxidase industrially used for dairy bleaching shows the highest singlet‐oxygen activity and the lowest inhibition. This enzyme was immobilized on a textile carrier and successfully applied for a chemical synthesis. Here, ascaridole was synthesized via enzymatically produced singlet oxygen.
The arrival of high-mobility two-dimensional materials like graphene leads to the renaissance of former vertical semiconductor–metal–semiconductor (SMS) hot electron transistors. Because of the monolayer thickness of graphene, improved SMS transistors with a semimetallic graphene-base electrode are now feasible for high-frequency applications. In this study we report about a device that consists of amorphous silicon, graphene, and crystalline silicon. For the first time, this device is fabricated by a four-mask lithography process which leads to significant improvements in the device performance. A strongly increased common-emitter current gain of 2% could be achieved while the on–off ratio improved to 1.6 × 105, which is already higher than predicted theoretically. This could be mainly attributed to better interface characteristics and decreased lateral dimensions of the devices. A cutoff frequency of approximately 26 MHz could be forecasted based on the DC measurements of the device.