Since environmental pollution has exceeded the limit of natural purification, [1] semiconductor-based photocatalytic reactions have attracted intense interest as an effective way of purifying air and water contaminants. [2] Among the various semiconductors, zinc oxide, with a direct wide bandgap (DE = 3.37 eV), is of special importance for the photocatalytic generation of hydrogen peroxide, [3] which can be utilized for the degradation of organic pollutants and the sterilization of bacteria and viruses. [2,4] Due to the fact that a photocatalytic reaction occurs at the interface between catalyst surfaces and organic pollutants, [2] it is highly feasible that the photocatalytic activity of ZnO is strongly dependent on the growth direction of the crystal plane. Such speculation gives us the impetus to explore the relationship between surface orientation of ZnO crystals and their photocatalytic efficiency. However, due to an intrinsic anisotropy in the growth rate v of ZnO,, hexagonal rods elongated along the c-axis have been predominantly synthesized. [5,6] Such an anisotropic tendency in crystal growth makes it difficult to directly probe the relationship between face orientation and photocatalytic activity. Here we report the novel face-tunable synthesis of nano-and microscale ZnO crystals with different ratios of polar to nonpolar faces. With these morphology-controlled crystals, we were able to clearly demonstrate a strong dependence of photocatalytic activity on a specific crystal plane.In Figure 1, we show schematic models for face-tunable synthetic routes to ZnO crystals. The morphologies of the resulting ZnO crystals were investigated with field-emission scanning electron microscopy (FESEM), as shown in Figure 2, and the theoretical surface areas of four different samples, estimated from the FESEM results, are summarized in Table 1.First, hexagonal ZnO nanorods were prepared simply by hydrothermal treatment of dip-coated ZnO nanoparticles on a Si wafer with a uniform size of 4 nm (Fig. 1a).[6a] The corresponding FESEM image of Figure 2a reveals the formation of a dense array of ZnO nanorods with a uniform diameter of 100 nm and a length of 1.5 lm. Due to a one-dimensional nanostructure extended along the [0001] direction, the ZnO nanorods have a larger population of nonpolar {011 0} faces than polar {0001} ones. In order to suppress crystal growth along the [0001] axis, we tried to protect the Zn 2+ -terminated (0001) plane, that is, Zn (0001), through complexation between Zn 2+ ions and citrate ligands. [7] On the basis of this strategy, hexagonal nanoplates with a uniform diameter of 1.0 lm and a thickness of 50 nm were successfully obtained, as can be seen clearly from the FESEM image in Figure 2b. Such formation of nanoplates with a high proportion of polar {0001} planes is surely due to a strong suppression of crystal growth along the [0001] axis with a relative enhancement of crystal growth along the [011 0] direction, as illustrated in Figure 1b. Similarly, the tailored synthesis of diverse ZnO na...

Hepatocyte growth factor (HGF) has been shown to induce angiogenesis in vivo and has potential as a candidate gene for 'therapeutic angiogenesis'. In vivo, two isoforms of HGF, HGF 723 and HGF 728 , consisting of 723 and 728 amino acids, are generated through alternative splicing between exons 4 and 5, but the biological effects of their coexpression have not yet been elucidated. In this study, we generated a series of genomic-complementary DNA (cDNA) hybrids of the HGF gene by inserting various truncated intron 4 into the junction of exons 4 and 5 of HGF cDNA and analyzed the biological activities of these hybrid constructs. We showed that: (1) the hybrid called HGF-X7, which contained 1502 base pairs of intron 4, could drive a higher level of HGF expression than other hybrid constructs and cDNAs of each isoform alone; (2) the pCK vector was most efficient for the gene expression of HGF-X7; (3) coexpression of both isoforms of HGF could more efficiently induce the migration of human umbilical vein endothelial cell (HUVEC) and of the mouse myoblast cell line C 2 C 12 myoblasts than a single isoform of HGF and human vascular endothelial growth factor (VEGF) 165 at a given concentration; (4) intramuscular administration of pCK-HGF-X7 resulted in transient and localized HGF expression in the injected muscle without an increase in the HGF protein levels in other tissues including serum; and (5) intramuscular injection of pCK-HGF-X7 could more efficiently increase the number of angiographically recognizable collateral vessels, as well as improve an intra-arterial Doppler wiremeasured blood flow in the rabbit model of hindlimb ischemia when compared with the identical vector encoding VEGF 165 gene. These results showed that transfer of the genomiccDNA hybrid of the HGF gene could be used as a potential therapeutic approach to human vascular diseases.

These results demonstrate that transfer of the genomic-cDNA hybrid expressing both isoforms of the HGF gene might provide higher therapeutic effects than the cDNA sequence producing HGF(728) alone in the treatment of ischemic heart disease.

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A novel method for switching the direction of surface plasmon polarition (SPP) launching is proposed. The principle behind the switching mechanism is based on the relative phase difference between the reference beam and the control beam. Selective guidance of the direction of SPP can be explained by the composition of the charge parity that is induced near the slit edge, which is caused by interference created by two incident beams. The switching of SPP launching direction could be implemented by simple phase modulation of the control beam when the slit parameters satisfy the specific conditions at the designed specific wavelength. An experimental demonstration, in good agreement with numerical results, shows that our configuration of SPP switching can be operated by a quite simple interaction.

The basic theory of cross-talking signals between counter-streaming electron beams in a vacuum tube oscillator consisting of two two-cavity klystron amplifiers reversely coupled through input/output slots is theoretically investigated. Application of Kirchhoff’s laws to the coupled equivalent RLC circuit model of the device provides four nonlinear coupled equations, which are the first-order time-delayed differential equations. Analytical solutions obtained through linearization of the equations provide oscillation frequencies and thresholds of four fundamental eigenstates, symmetric/antisymmetric 0∕π modes. Time-dependent output signals are numerically analyzed with variation of the beam current, and a self-modulation mechanism and transition to chaos scenario are examined. The oscillator shows a much stronger multistability compared to a delayed feedback klystron oscillator owing to the competitions among more diverse eigenmodes. A fully developed chaos region also appears at a relatively lower beam current, ∼3.5Ist, compared to typical vacuum tube oscillators (10-100Ist), where Ist is a start-oscillation current.

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