Simultaneous measurement of velocity and pressure in a plane jet

A new technique was developed for the simultaneous measurement of velocity and pressure in turbulent flows. To accomplish this objective, a new probe (hereafter called the combined probe) that consists of an X-type hot-wire probe and a newly devised pressure probe was developed. The pressure probe was miniaturized by the MEMS fabrication process and by using a 0.1-in. microphone as a pressure sensor for improving the spatial resolution. This pressure probe was placed between two hot-wire sensors of which the X-type hot-wire probe was composed. The pressure probe was given a hemispherical tip, like that of a pitot tube, because an earlier pressure probe with a conical tip suffered from a reduction in spatial resolution. The spatial arrangement of the pressure probe and the hot-wire probe for the combined probe was carefully determined, because there was a risk that the measurement accuracy of one probe will be influenced by disturbances caused by the other probe when the two probes were placed very close to each other. Therefore, the combined probe was arranged to engender no noticeable interference between the velocity data and the pressure data measured by their respective probes. As one application of this combined probe, simultaneous measurements of pressure and two components of instantaneous velocity were performed in a plane jet. The turbulent energy budget and the cross-correlation coefficient of velocity and pressure in the intermittent region of the plane jet were estimated. The results show that the mean streamwise velocity, velocity fluctuation, and pressure fluctuation profiles were consistent with those measured individually using the X-type hot-wire probe or pressure probe. Moreover, it was shown that the integral value of the diffusion term (which should theoretically be equal to zero) in the turbulent energy transport equation was closer to zero than previous reports (Bradbury in J Fluid Mech 23(Part 1):31–64, 1965). In addition, the time variation of the cross-correlation coefficient in the intermittent region supports the vortex structure model predicted in previous studies (Browne et?al. in J Fluid Mech 149:355–373, 1984; Tanaka et?al. JSME Int J Ser B 49(4):899–905, 2006; Sakai et?al. J Fluid Sci Technol 2(3):611–622, 2007).     

Quasiparticle scattering induced by charge doping of iron-pnictide superconductors probed by collective vortex pinning

Charge doping of iron-pnictide superconductors leads to collective pinning of flux vortices, whereas isovalent doping does not. Moreover, flux pinning in the charge-doped compounds is consistently described by the mean-free path fluctuations introduced by the dopant atoms, allowing for the extraction of the elastic quasiparticle scattering rate. The absence of scattering by dopant atoms in isovalently doped BaFe2(As(1-x)P(x))(2) is consistent with the observation of a linear temperature dependence of the low-temperature penetration depth in this material.     

Nondispersive fermi arcs and the absence of charge ordering in the pseudogap phase of Bi2Sr2CaCu2O8+delta

The autocorrelation of angle resolved photoemission data from the high temperature superconductor Bi(2)Sr(2)CaCu(2)O(8+delta) shows distinct peaks in momentum space which disperse with binding energy in the superconducting state, but not in the pseudogap phase. Although it is tempting to attribute a nondispersive behavior in momentum space to charge ordering, a deconstruction of the autocorrelation reveals that the nondispersive peaks arise from the tips of the Fermi arcs, which themselves do not change with binding energy.     

Fabrication of Ge-channel MOSFETs by using replacement gate process and selective epitaxial growth

We fabricated Ge-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) by using replacement gate process and selective epitaxial growth. In our method, thin Ge layers were selectively grown on the channel region of MOSFETs after the removal of a sacrificial gate stack structure and the etching of the channel region. Ge layers with a smooth surface and a good morphology could be obtained by using the thin Si_0.5Ge_0.5 buffer layer. Dislocations were observed in the epitaxial layers and near the interface between the epitaxial layer and the substrates. We consider that these dislocations degrade the device performance. Although the electrical characteristics of the obtained MOSFETs need further improvement, our method is one of the promising candidates for the practical fabrication process of Ge-channel MOSFETs.     

Many-body interactions in hole-doped high-Tc cuprates studied by high-resolution ARPES

We have performed high-resolution angle-resolved photoemission spectroscopy on hole-doped high-T_c cuprate superconductors (HTSCs) to study many-body interaction and the universality of low-energy excitation gap. In Bi₂Sr₂CaCu₂O₈ (Bi2212), we observed a kink in the dispersion in the off-nodal region in the superconducting state, which remarkably weakens on impurity substitution. We also find that the appearance of the kink in the off-nodal region is a common feature of Bi2212 and La_1.85Sr_0.15CuO₄ (LSCO), while the energy scale is remarkably different between two compounds (70 and 20 meV). We discuss universality of the kink in dispersion in the hole-doped HTSCs in terms of the coupling of electrons with spin fluctuations.     

Studies on aldose reductase inhibitors from natural products. IV. Constituents and aldose reductase inhibitory effect of Chrysanthemum morifolium, Bixa orellana and Ipomoea batatas.

The hot water extracts of Chrysanthemum morifolium, Bixa orellana and Ipomoea batatas, were found to have potent inhibitory activity towards lens aldose reductase (AR). Ellagic acid (4) was isolated from C. morifolium and I. batatas, isoscutellarein (7) from B. orellana and 3,5-dicaffeoylquinic acid (10) from I. batatas, respectively, as potent inhibitors.     

Stereochemical studies-LVIII: Synthesis of optically active compounds by the novel use of meso-compound-2. efficient synthesis of an optically pure steroid intermediate

In order to explore the general application of a novel method for preparing optically active compounds, synthesis of the optically pure steroid intermediate((?)-1) has been examined by employing the diol(2) as a meso-compound and N-mesyl-(S)-phenylalanyl chloride(3) as a source of the optically active functional group.