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In this paper, we first experimentally demonstrate a 550 Mbit/s real-time visible light communication (VLC) system based on nonreturn-to-zero on-off keying (NRZ-OOK) modulation of a commercial phosphorescent white light LED. The 3-dB modulation bandwidth of such devices is only a few megahertz. We proposed an analog pre-emphasis circuit based on NPN transistors and an active post-equalization circuit based on an amplifier to enhance the 3-dB bandwidth of VLC link. Utilizing our proposed pre-emphasis and post-equalization circuits, the 3-dB bandwidth of VLC link could be extended from 3 to 233 MHz with blue-filter, to the best of our knowledge, which is the highest ever achieved in VLC systems reported. The achieved data rate was 550 Mbit/s at the distance of 60 cm and the resultant bit-error-ratio (BER) was 2.6 × 10(-9). When the VLC link operated at 160 cm, the data rate was 480 Mbit/s with 2.3 × 10(-7) of BER. Our proposed VLC system is a good solution for high-speed low-complexity application.

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The structure of an Al-Ni-Co decagonal ͑d-͒ quasicrystal has been investigated by scanning tunneling microscopy ͑STM͒. STM images with atomic-scale resolution have been obtained successfully for the surfaces of both tenfold and twofold planes. On the tenfold surface, large terraces and monoatomic-layer steps are formed. The symmetry of each layer is not decagonal but pentagonal and the two adjacent layers are related by the inversion symmetry. The step lines are rough, which can be attributed to the existence of many symmetrically equivalent low-energy steps. The atom adsorptions are often observed at locally symmetric sites. An analysis based on the high-dimensional description of the quasicrystalline structure has shown that the structure has nearly perfect quasiperiodic order for the decagonal quasicrystal. On the twofold surface, interlayer phason defects are observed, but the density of them is quite low. This fact indicates that the d-quasicrystal of the present sample is not in the random tiling state in which the configurational entropy related to the phason disorder stabilizes the quasicrystal.

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A stable icosahedral phase has been found in a series of Cd65Mg20RE15 (RE=Y, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) alloys. These icosahedral alloys have quasilattice parameters from 0.5571 to 0.5799 nm. Electron diffraction study confirmed that the icosahedral quasicrystals have a primitive icosahedral structure.

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