Blue-shifting of coherent plasmon radiation due to Landau damping
Restricting the wave vector of coherent plasmons excited by ultrashort laser pulses results in a frequency blue-shift of the emitted THz radiation, consistent with the onset of Landau damping.
Coherent plasmons in InSb
We study coherent plasmons in the narrow-gap semiconductor InSb by measuring the far-infrared electromagnetic radiation they emit. These collective oscillations are excited with ultrashort, near-infrared laser pulses having photon energy far above the semiconductor band gap. Coherent plasmon behavior is characterized as a function of temperature, doping density, optically injected carrier density, and spatial confinement.
Molecular diversity of skin mucus lectins in fish.
Among lectins in the skin mucus of fish, primary structures of four different types of lectin have been determined. Congerin from the conger eel Conger myriaster and AJL-1 from the Japanese eel Anguilla japonica were identified as galectin, characterized by its specific binding to beta-galactoside. Eel has additionally a unique lectin, AJL-2, which has a highly conserved sequence of C-type lectins but displays Ca(2+)-independent activity. This is rational because the lectin exerts its function on the cutaneous surface, which is exposed to a Ca(2+) scarce environment when the eel is in fresh water. The third type lectin is pufflectin, a mannose specific lectin in the skin mucus of pufferfish Takifugu rubripes. This lectin showed no sequence similarity with any known animal lectins but, surprisingly, shares sequence homology with mannose-binding lectins of monocotyledonous plants. The fourth lectin was found in the ponyfish Leiognathus nuchalis and exhibits homology with rhamnose-binding lectins known in eggs of some fish species. These lectins, except ponyfish lectin, showed agglutination of certain bacteria. In addition, pufflectin was found to bind to a parasitic trematode, Heterobothrium okamotoi. Taken together, these results demonstrate that skin mucus lectins in fish have wide molecular diversity.