Polymer-supported bisBINOL ligands for the immobilization of multicomponent asymmetric catalysts

[reaction: see text] Polymer-supported bisBINOL ligands were successfully utilized for the immobilization of multicomponent asymmetric catalysts. The polymer-supported Al-Li-bis(binaphthoxide) (ALB) catalyst was more effective than the dendrimer-supported ALB in the Michael reaction of 2-cyclohexen-1-one with dibenzyl malonate affording the adduct in 91% yield with 96% ee. The polymer was also effective for the immobilization of a mu-oxodititanium complex that promoted carbonyl-ene reaction of ethyl glyoxalate with alpha-methyl styrene to provide the adduct with up to 98% ee.     

High-speed separation system of randomly suspended single living cells by laser trap and dielectrophoresis

We developed a new system for random separation of a single microorganism, such as a living cell and a microbe, in the microfluidic device under the microscope by integrating the laser-trapping force and dielectrophoretic (DEP) force. An arbitrarily selected single microbe could be isolated in a microchannel, despite the presence of a large number of microbes in solution. Once the target microbe is trapped at the focal point of the laser, we can easily realize exclusion of excess microbes around the target by controlling the electric field, while keeping the target trapped by the laser at the focal point. To realize an efficient separation system, we proposed a new separation cell and produced it by microfabrication. Flow speed in the microchannel is adjusted and balanced to realize high-speed and high-purity extraction of the target. Some preliminary experiments are conducted to show the effectiveness. The target is trapped by the laser, transported, and is taken out from the extraction port. Total separation time is less than 20 s. Our method is extremely useful in the pure cultivation of the cell and will be a promising method for biologists in screening useful microbes.     

Slow spin relaxation of Rb atoms confined in glass cells filled with dense 4He gas at 1.85 K

At temperatures below 2.1 K, long-lived gaseous Rb atoms in glass cells have been generated with a simple method: irradiating the cells, containing 4He gas and Rb metal, with a cw laser. The obtained atomic Rb density ( approximately 10(8) cm(-3)) decreases with a 1/e time constant of about 10 s at 1.85 K. We have performed optical pumping of the Rb atoms and measured the longitudinal electronic spin relaxation time at 1.85 K as well. For processes (such as Rb-He collisions) which do not remove the atomic Rb from the vapor, this relaxation time is found to be about 60+/-15 s.     

First-principles study of the (0 0 1) surface of cubic SrZrO3

Density functional calculations have been used to investigate the (0 0 1) surface of cubic SrZrO₃ with both SrO and ZrO₂ termination. Surface structure and electronic structure have been obtained. The SrO surface is found to be similar to its counterpart in SrTiO₃, while there are marked differences between the ZrO₂ and TiO₂ terminations in SrZrO₃ and SrTiO₃, respectively, concerning surface relaxation and rumpling. For the ZrO₂-terminated surface of SrZrO₃, the covalency of the interaction between the outmost Zr and the O beneath is enhanced as a result of their bond contraction. The band gap reduction and the presence of the surface states are also discussed in relation with the behavior of the electrostatic potential.     

22 dB all-fiber green amplifier using Er-doped fluoride fiber

We demonstrate a 22 dB all-fiber amplifier at 546 nm using Er³⁺-doped fluoride fiber by forward upconversion pumping of a 974 nm laser diode. The gain saturation effects and the power conversion efficiency of this amplifier are investigated in detail based on gain characteristics and numerical simulations.     

Far infrared optical properties of high Tc superconductors LnBa2Cu3Ox (Ln=Y, Ho, Er, Sm, GD, Dy, Eu, Pr)

Systematic measurements of the far infrared reflection spectra of high T_c superconductors LnBa₂Cu₃O_x for various Ln as shown in the title were performed. Infrared reflection spectra of tetragonal LnBa₂Cu₃O_x exhibit Reststrahlen vibration near 640, 590, 530, 355 and 250 cm^–1, common to these materials, and the spectra of the orthorhombic LnBa₂Cu₃O_x exhibit the characteristics of free carriers except PrBa₂Cu₃O_x with weak phonon structures near 617, 570, 317 and 285 cm^–1. PrBa₂Cu₃O_x is not a superconductor, and it has no characteristic broad band due to free carriers for all x in the range of 6 to 7. Lattice dynamical calculation was performed by the use of the shell model and the calculated results express quite well the characteristic features of infrared experiments.