Conceptual design of a novel insertion device using bulk superconducting magnet

An undulator or a wiggler with a strong magnetic field will play an important role in future synchrotron light sources, free electron lasers, and linear colliders. We proposed the bulk high critical temperature superconductor staggered array undulator (Bulk HTSC SAU) in order to generate a strong periodic field. The Bulk HTSC SAU consists of stacked bulk high-Tc superconductors (HTSs) and a solenoid magnet which is used to magnetize the bulk HTSs. A periodic magnetic field was produced and controlled using a prototype of the Bulk HTSC SAU using 11 pairs of REBaCuO bulk HTSs at 77 K. The expected performance at low temperatures around 20 K is calculated using a loop current model.     

Superconducting property of Zr–Co–Al–Nb metallic glasses

The superconducting property of Zr₅₅Co_(30?x)Al₁₅Nb_x (x = 0–20 at.%) metallic glasses fabricated by rapid solidification was investigated. The Zr₅₅Co_(30–x)Al₁₅Nb_x (x = 5–20 at.%) metallic glasses with a mixture structure of amorphous and nanocrystal phases exhibited superconductivity of T_c,on = 1.8–2.6 K. The maximum T_c,on = 2.6 K was obtained for the Zr₅₅Co₁₀Al₁₅Nb₂₀ metallic glass. This was attributable to the superconducting property of nanocrystalline particles contained in the Zr₅₅Co₁₀Al₁₅Nb₂₀ alloy. The increase of Nb element in the Zr₅₅Co_(30–x)Al₁₅Nb_x alloy led to the increase of T_c,on and the decrease of glass transition temperature. The glass transition temperature was between 704 and 749 K for the Zr₅₅Co_(30–x)Al₁₅Nb_x (x = 0–20 at.%) alloys. The temperature interval of supercooled liquid state was between 51 and 68 K for the Zr₅₅Co_(30–x)Al₁₅Nb_x (x = 0–20 at.%) alloys.     

Single-nanometer focusing of hard x-rays by Kirkpatrick-Baez mirrors

We have constructed an extremely precise optical system for hard-x-ray nanofocusing in a synchrotron radiation beamline. Precision multilayer mirrors were fabricated, tested, and employed as Kirkpatrick-Baez mirrors with a novel phase error compensator. In the phase compensator, an at-wavelength wavefront error sensing method based on x-ray interferometry and an in situ phase compensator mirror, which adaptively deforms with nanometer precision, were developed to satisfy the Rayleigh criterion to achieve diffraction-limited focusing in a single-nanometer range. The performance of the optics was tested at BL29XUL of SPring-8 and was confirmed to realize a spot size of approximately 7 nm.     

Communication: Quantum polarized fluctuating charge model: a practical method to include ligand polarizability in biomolecular simulations

We present a simple and practical method to include ligand electronic polarization in molecular dynamics (MD) simulation of biomolecular systems. The method involves periodically spawning quantum mechanical (QM) electrostatic potential (ESP) calculations on an extra set of computer processors using molecular coordinate snapshots from a running parallel MD simulation. The QM ESPs are evaluated for the small-molecule ligand in the presence of the electric field induced by the protein, solvent, and ion charges within the MD snapshot. Partial charges on ligand atom centers are fit through the multi-conformer restrained electrostatic potential (RESP) fit method on several successive ESPs. The RESP method was selected since it produces charges consistent with the AMBER/GAFF force-field used in the simulations. The updated charges are introduced back into the running simulation when the next snapshot is saved. The result is a simulation whose ligand partial charges continuously respond in real-time to the short-term mean electrostatic field of the evolving environment without incurring additional wall-clock time. We show that (1) by incorporating the cost of polarization back into the potential energy of the MD simulation, the algorithm conserves energy when run in the microcanonical ensemble and (2) the mean solvation free energies for 15 neutral amino acid side chains calculated with the quantum polarized fluctuating charge method and thermodynamic integration agree better with experiment relative to the Amber fixed charge force-field.     

Labeling of alprenolol with fluorescent aryl iodide as a reagent based on Mizoroki-Heck coupling reaction

A novel fluorescent labeling method for alprenolol was developed based on Mizoroki-Heck coupling reaction. We designed and synthesized fluorescent aryl iodide, 4-(4,5-diphenyl-1H-imidazol-2-yl)iodobenzene (DIBI) as a labeling reagent. DIBI has a lophine skeleton carrying an iodide atom acting as fluorophore and reactive center, respectively. In order to evaluate the usefulness of DIBI, a high-performance liquid chromatography (HPLC) with fluorescence detection method was developed for the determination of alprenolol as a model compound of terminal double bond. The fluorescent labeling of alprenolol with DIBI was achieved in the presence of palladium acetate as a catalyst, and the labeled alprenolol was detected fluorometrically. In addition, it was found that the fluorescence of DIBI derivative increased and red shifted when compared with that of DIBI. Furthermore, the proposed method could be applied to determine the alprenolol concentration in rat plasma after administration of alprenolol without interferences from biological components. The detection limit (S/N=3) for alprenolol in rat plasma was 0.74 ng/mL (30 fmol on column).     

Photosensitization reaction-induced acute electrophysiological cell response of rat myocardial cells in short loading periods of talaporfin sodium or porfimer sodium

Electrophysiological responses of rat myocardial cells to exogenous photosensitization reactions for a short period of incubation with two photosensitizers, talaporfin sodium or porfimer sodium, were measured in a subsecond time scale. The loading period of the photosensitizer when the photosensitizer might not be taken up by the cells was selected as 15min, which was determined by the fluorescence microscopic observation. We measured the intracellular Ca(2+) concentration ([Ca(2+) ](in) ) by using a fluorescent Ca(2+) indicator, Fluo-4 AM, under a high-speed confocal laser microscope to evaluate the acute electrophysiological cell response to the photosensitization reaction. The measured temporal change in Fluo-4 fluorescence intensity indicated that the response to the photosensitization reaction might be divided into two phases in both photosensitizers. The first phase is acute response: disappearance of Ca(2+) oscillation when irradiation starts, which might be caused by ion channel dysfunction. The second phase is slow response: [Ca(2+) ](in) elevation indicating influx of Ca(2+) due to the concentration gradient. The continuous Ca(2+) influx followed by changes in cell morphology suggested micropore formation on the surface of the cell membrane, resulting in necrotic cell death.     

Novel synthesis of oxa[9]helicenes by Lawesson’s reagent-mediated cyclization of helical quinone derivatives

New oxa[9]helicenes which possess one furan ring have been readily prepared by reactive helical quinone with Lawesson’s reagent or phosphorus pentasulfide in good yields. The versatility of this protocol has been demonstrated with various substituted helical quinones.     

Connectivity of PS-b-PEO templated spherical pores in titanium oxide films

Titania films having relatively uniform spherical pores were successfully fabricated using polystyrene-block-poly(ethylene oxide) (PS(n)-b-PEO(m)) diblock copolymers. Depending on the molecular weight of PS(n)-b-PEO(m), the spherical pores were varied from large mesopores (n = 40,000, m = 53,000; ～40 nm) to macropores (n = 58,600, m = 71,000; ～60 nm, n = 100,000, m = 150,000; ～100 nm) in diameter. It was confirmed that the porous structures were thermally stable with crystallization of the titania frameworks. Interconnectivity between the spherical pores was reliant on the micellar arrangement of hydrophobic PS cores, while the amount of isolated pores was increased in the films prepared using low molecular weight PS(n)-b-PEO(m). The presence of such isolated pores was confirmed on the basis of adsorption experiments by using a globular hemoprotein cytochrome c (ca. 3.1 nm). Highly interconnected spherical pores, which were preferentially fabricated using high molecular weight PS(n)-b-PEO(m), were quite helpful for smooth diffusion-adsorption of bulky proteins inside the porous films.     

Benzyl radical addition reaction through the homolytic cleavage of a benzylic C-H bond

Direct generation of a benzyl radical by C-H bond activation of toluenes and the addition reaction of the resulting radical to an electron deficient olefin were developed. The reaction of dimethyl fumarate with toluene in the presence of Et(3)B as a radical initiator at reflux afforded 2-benzylsuccinic acid dimethyl ester in good yield.     

In situ kinetic study on hydrothermal transformation of D-glucose into 5-hydroxymethylfurfural through D-fructose with 13C NMR

Kinetics of hydrothermal reaction of D-glucose was investigated at 0.02 M over a temperature range of 120-160 °C by applying in situ (13)C NMR spectroscopy. D-Glucose was found to be reversibly transformed first into D-fructose (intermediate) and successively into 5-hydroxymethylfurfural (5-HMF) through dehydration. The carbon mass balance has been kept within the detection limit, and no other reaction pathways are present. The hydrothermal reaction of d-glucose is thus understood as that of D-fructose in the sense that the D-glucose reaction proceeds only through D-fructose. All the isomers of D-glucose and D-fructose were detected by the in situ (13)C NMR in D(2)O: they are the open chains and the pyranoses and furanoses of α- and β-types. The β-forms are the most stable due to the hydration. For both D-glucose and D-fructose, the isomers are in a rapid equilibrium for each monosaccharide, and they are treated collectively in the kinetic analysis of the slower hydrothermal reactions. The reactions are of the first order with respect to the concentrations of D-glucose and D-fructose, and D-glucose converts to 5-HMF on the order of hours. The kinetic parameters were determined by the in situ method.