Japan's superconducting Maglev train

We have developed a Maglev train under the guidance of the Japanese Ministry of Transport. The Maglev train is an advanced train that can run more than 500 km/h with a linear synchronous motor (LSM) that has both a superconducting magnet on board and an armature coil in the ground. The Maglev train was tested on the Yamanashi Maglev test line. Tests began in 1997, which exercised various functions of performance. The main results of the tests are reported in this article     

Elementary processes of DNA surface hybridization resolved by single-molecule kinetics: implication for macroscopic device performance

Direct monitoring of single-molecule reactions has recently become a promising means of mechanistic investigation. However, the resolution of reaction pathways from single-molecule experiments remains elusive, primarily because of interference from extraneous processes such as bulk diffusion. Herein, we report a single-molecule kinetic investigation of DNA hybridization on a metal surface, as an example of a bimolecular association reaction. The tip of the scanning tunneling microscope (STM) was functionalized with single-stranded DNA (ssDNA), and hybridization with its complementary strand on an Au(111) surface was detected by the increase in the electrical conductance associated with the electron transport through the resulting DNA duplex. Kinetic analyses of the conductance changes successfully resolved the elementary processes, which involve not only the ssDNA strands and their duplex but also partially hybridized intermediate strands, and we found an increase in the hybridization efficiency with increasing the concentration of DNA in contrast to the knowledge obtained previously by conventional ensemble measurements. The rate constants derived from our single-molecule studies provide a rational explanation of these findings, such as the suppression of DNA melting on surfaces with higher DNA coverage. The present methodology, which relies on intermolecular conductance measurements, can be extended to a range of single-molecule reactions and to the exploration of novel chemical syntheses.

Hybridization of a single DNA molecule on a surface was investigated by electrical conductance measurements. The hybridization efficiency increases with increasing the DNA concentration, in contrast to preceding studies with ensemble studies.     

Cellular uptake and photocytotoxicity of glycoconjugated porphyrins in HeLa cells

Thirty-two glycoconjugated porphyrins were synthesized by a modification of Lindsey method in the presence of Zn(OAc)(2).2H(2)O as a template. The Zn(2+) ion template strategy improved the yield about three-fold in the case of meta-substituted tetraphenylporphyrins. In addition, free-base porphyrins were obtained almost quantitatively by demetalation with 4 M HCl. Sixteen deacetylated glycoconjugated porphyrins were tested as candidate photodynamic therapy (PDT) drugs using HeLa cells. Most of the deacetylated glycoconjugated porphyrins showed higher cellular uptake than tetraphenylporphyrin tetrasulfonic acid (TPPS), and 5,10,15,20-tetrakis[4-(beta-D-arabinopyranosyloxy)phenyl]porphyrin (p-5d) in particular showed 18.5-fold higher uptake than TPPS. The photocytotoxicity of 5,10,15,20-tetrakis[4-(beta-D-glucopyranosyloxy)phenyl]porphyrin (p-5a), p-5d and TPPS was examined with HeLa cells, using a light dose of 16 J/cm(2). These photosensitizers had no cytotoxicity in the dark, but their photocytotoxicity increased in the order of TPPS < p-5a < p-5d. These results suggest p-5d is a good candidate for a PDT drug.     

THE EFFECT OF LIGHT ON THE OCELLAR PIGMENT OF SPIROCODON, AN ANTHOMEDUSA

Abstract— The ocellar pigment of Spirocodon saltatrix was extracted with 2% mildly alkaline cetyltrimethylammonium bromide (CTAB) and 90% methanol acidified with HCl. In the case of CTAB-extracted pigment, maximum changes in optical density upon illumination occurred in mildly alkaline media under aerobic conditions and in neutral media under anaerobic conditions. The density spectrum of the sample illuminated under anaerobic conditions closely resembled that of the reduced form of the pigment illuminated in the presence of air. When reduced in darkness, the pigment became photostable and its density spectrum differed from that of the pigment reduced after illumination. On aeration of the pigment solution illuminated under anaerobic conditions, its density spectrum in the visible range became similar to that of the pigment illuminated in the presence of air. A trace of air dissolved in experimental media caused auto-oxidation of the reduced form, during the process of which a definite isosbestic point was observed at 480 mμ. Under anaerobic conditions, short period of illumination produced changes in spectral absorbance only in the visible range. Changes in the u.v. range required longer exposures. The pigment extracted with acidified methanol was readily auto-oxidizable and it was the reduced form which showed photosensitivity, though the degree of sensitivity was extremely low. The density spectrum of illuminated pigment resembled that of the oxidized form. From these experiments, a tentative scheme involving an electron transfer system has been suggested for the chain of photic reaction of the anthomedusan ocellar pigment.     

Radiochemical challenges in the study of endohedral fullerenes and MD simulation

The formation of atom-doped fullerenes has been investigated by using several types of radionuclides produced by nuclear reactions. From the trace of the radioactivities after high performance liquid chromatography (HPLC), it was found that formation of endohedral fullerenes (or heterofullerene) with small atoms (Be, Li), noble-gas atoms (Kr, Xe) and 4B–6B elements (Ge, As, Se, Sb, Te etc.) is possible by a recoil process following the nuclear reaction. In order to show the possibility of creating endohedral fullerenes by inserting a foreign atom with a suitably high kinetic energy into C₆₀, we have carried out large-scale ab initio molecular dynamics simulations on the basis of the all-electron mixed-basis approach with atomic orbitals and plane waves for Li, Be, N, O, Na, S, Cl, K, V, Cu, As, Se, Sb, Te, Kr, Xe. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mercuric triflate-catalyzed tandem cyclization leading to polycarbocycles

[reaction: see text] We developed Hg(OTf)2-catalyzed cyclization of (E)-1,3-dimethoxy-5-(4-methyl-3-nonen-7-ynyl)benzene leading to the formation of (4aS,10aS)-3,4,4a,9,10,10a-hexahydro-5,7-dimethoxy-1,4a-dimethylphenanthrene in 98% yield with up to 100 catalytic turnovers. This is the first mercuric salt-catalyzed biomimetic tandem cyclization.     

Simultaneous determination of iron and copper ions by low-injection analysis with a multichannel photodiode-array detector

Iron(II) and copper(II) ions are determined simultaneously in a simple manifold by using a multichannel photodiode-array detector. 1-(2-Pyridlazo)-2-hydroxy-7-sulfonaphthalene (PAN-7S) is used as the sole chromogenic reagent. The absorbance at 550 nm is related to the PAN-7S chelates of iron(II) and copper(II)and that at 764 nm to the iron(II) chelate alone. Calibrations are linear over the range 0–8.0 x 10^?6 M for each metal. Interference from zinc is avoided by addition of nitrilotriacetic acid; nickel interferes. Appliation to the determination of iron and copper ions in blood serum is discussed.     

Generalized diffusion equation of interacting brownian particles

Macroscopic behavior of a system of brownian particles interacting with each other through potential forces is described by a generalized diffusion equation (GDE) for the density of particles. The diffusion coefficient in the GDE is given by the generalized Stokes—Einstein relation and generally depends on the density. In the presence of long-range interactions, the GDE becomes non-local in space. When a Coulomb interaction exists, the GDE corresponds to an improvement of the Poisson—Boltzmann equation.     

Bismuth triflate-chiral bipyridine complexes as water-compatible chiral Lewis acids

[reaction: see text] Catalytic asymmetric hydroxymethylation of silicon enolates with an aqueous formaldehyde solution has been developed using a chiral bismuth complex. This is the first example of highly enantioselective reactions using a chiral bismuth catalyst in aqueous media. In this paper, we have added Bi(OTf)(3)-1 complex as a "water-compatible Lewis acid". Bi(OTf)3 is unstable in the presence of water but is stabilized by the basic ligand.