Effect of charge ordering and disordering on terahertz radiation characteristics of magnetoresistive Pr0.7Ca0.3MnO3 thin films

Terahertz (THz) radiation from voltage-biased photoswitching devices made on magnetoresistive manganite Pr0.7Ca0.3MnO3 have been investigated for thin films grown under different conditions. We find that the temperature dependence of THz radiation near the charge-ordering temperature strongly depends on the growth condition of Pr0.7Ca0.3MnO3, whereas THz radiation shows no such temperature dependence near the spin-ordering temperature.     

Sesquiterpene aminoquinones, from a marine sponge, induce erythroid differentiation in human chronic myelogenous leukemia, K562 cells

A new sesquiterpene aminoquinone, 5-epi-smenospongorine, together with nine known sesquiterpene quinone/phenols, was isolated as differentiation-inducing substances to K562 cells into erythroblast from the marine sponge Dactylospongia elegans. The structure-activity relationship study of these compounds clarified that the quinone skeleton is indispensable and the amino group plays an important role for their differentiation-inducing activity to K562 cells into erythroblast.     

Fabrication of a mid-IR wire-grid polarizer by direct imprinting on chalcogenide glass

A mid-IR wire-grid polarizer with a 500 nm pitch was fabricated on a low toxic chalcogenide glass (Sb-Ge-Sn-S system) by the thermal imprinting of periodic grating followed by the thermal evaporation of Al metal. After imprinting, deposition of Al on the grating at an oblique angle produced a wire-grid polarizer. The fabricated polarizer showed polarization with TM transmittance greater than 60% at 5-9 μm wavelengths and an extinction ratio greater than 20 dB at 3.5-11 μm wavelengths. This polarizer with a high extinction ratio can be fabricated more simply and less expensively than conventional IR polarizers.     

Cooling dynamics of self‐assembled monolayer coating for integrated gold nanocrystals on a glass substrate

Picosecond time‐resolved X‐ray diffraction has been used to study the nanoscale thermal transportation dynamics of bare gold nanocrystals and thiol‐based self‐assembled monolayer (SAM)‐coated integrated gold nanocrystals on a SiO₂ glass substrate. A temporal lattice expansion of 0.30–0.33% was observed in the bare and SAM‐coated nanocrystals on the glass substrate; the thermal energy inside the gold nanocrystals was transported to the contacted substrate through the gold–SiO₂ interface. The interfacial thermal conductivity between the single‐layered gold nanocrystal film and the SiO₂ substrate is estimated to be 45 MW m^?2 K^?1 from the decay of the Au 111 peak shift, which was linearly dependent on the transient temperature. For the SAM‐coated gold nanocrystals, the thermal dissipation was faster than that of the bare gold nanocrystal film. The thermal flow from the nanocrystals to the SAM‐coated molecules promotes heat dissipation from the laser‐heated SAM‐coated gold nanocrystals. The thermal transportation of the laser‐heated SAM‐coated gold nanocrystal film was analyzed using the bidirectional thermal dissipation model.