Simulation and Experimental Study of Wavefront Measurement Accuracy of the Pencil-Beam Method

Ultra-bright and high-coherence X-rays are now being used in synchrotron radiation facilities and X-ray free electron laser facilities. X-ray focusing techniques are essential to take full advantage of these excellent X-ray light sources. To meet the strong demand, high-quality X-ray focusing optics have been developed owing to the advancement of ultraprecision machining and measurement. State-of-the-art refractive lenses [1 C.G. Schroer, Applied Physics Letters 87, 124103 (2005).[Crossref], [Web of Science ®] , [Google Scholar]], zone plates [2 T. Chen, Optics Express 19, 19919 (2011).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]], and Laue lenses [3 H. Yan, Optics Express 19, 15069 (2011).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]] can be used to achieve X-ray focusing to a spot a few tens of nanometers.     

Photoionization cross sections with optimized orbital exponents within the complex basis function method

We show a new direction to expand the applicability of the complex basis function method for calculating photoionization cross sections through the imaginary part of the frequency-dependent polarizability. Based on the variational stability of the frequency-dependent polarizability, we made nonlinear optimizations of complex orbital exponents in basis functions representing continuum wave functions, and obtained fairly accurate results for H atom with only one or two complex basis functions particularly with dipole velocity gauge. Results were almost independent of whether Slater-type or Gaussian-type orbitals are used, implying the applicability to general many electron problems. The method was also applied to the (1)S (1s)(2) --> (1)P (1s)(1)(kp)(1) cross section of He atom and the optimized complex orbital exponents were related to those of H atom through the scaling property. The nonlinear optimizations have converged smoothly and the cross sections were in excellent agreement with experiment throughout wide photon energies, which suggest the effectiveness of the approach for many-electron systems.     

Parallel kinetic resolution of propargyl ketols: formal synthesis of (+)-bakkenolide A

We describe an intriguing new example of a parallel kinetic resolution; an asymmetric cyclization-carbonylation of propargyl ketols catalyzed by palladium(II) with chiral bisoxazoline (box) ligands. The 2S,3S enantiomer of (±)-6 was preferentially converted to 13 (45-49% yields, 37-46% ee), and the 2R,3R enantiomer of (±)-6 was preferentially converted to 14 (21-23% yields, 92-97% ee). As an application of this reaction, formal synthesis of (+)-bakkenolide A was achieved.     

Selective metal deposition on photoswitchable molecular surfaces

We report here a novel phenomenon: selective metal deposition on photoswitchable diarylethene (DAE) surfaces. Magnesium vapor was deposited by vacuum evaporation on the colored DAE but not on the uncolored surface. The selective deposition originates in the change of the glass transition temperature of the amorphous DAE film resulting from photoisomerization and therefore from changes of surface molecular motion. We clarified that Mg atoms on the uncolored surface actively migrated on the surface and were desorbed from the surface. The possibility of depositing other metals is also discussed. Light-controllable metal-integrated deposition was demonstrated as a new function of the photoswitchable molecular surfaces. This study reveals new features of the photoswitchable molecular surfaces, and their potential suggests bright prospects for future applications in organic electronics.     

Design, synthesis, and properties of 2',4'-BNA(NC): a bridged nucleic acid analogue

The novel bridged nucleic-acid analogue 2',4'-BNA(NC) (2'-O,4'-C-aminomethylene bridged nucleic acid), containing a six-membered bridged structure with an N-O linkage, was designed and synthesized efficiently, demonstrating a one-pot intramolecular NC bond-forming key reaction to construct a perhydro-1,2-oxazine ring (11 and 12). Three monomers of 2',4'-BNA(NC) (2',4'-BNA(NC)[NH], [NMe], and [NBn]) were synthesized and incorporated into oligonucleotides, and their properties were investigated and compared with those of 2',4'-BNA (LNA)-modified oligonucleotides. Compared to 2',4'-BNA (LNA)-modified oligonucleotides, 2',4'-BNA(NC) congeners were found to possess: (i) equal or higher binding affinity against an RNA complement with excellent single-mismatch discriminating power, (ii) much better RNA selective binding, (iii) stronger and more sequence selective triplex-forming characters, and (iv) immensely higher nuclease resistance, even higher than the S(p)-phosphorthioate analogue. 2',4'-BNA(NC)-modified oligonucleotides with these excellent profiles show great promise for applications in antisense and antigene technologies.     

Release and transfer of polystyrene dewetting pattern by hydration force

We studied the release and transfer of polystyrene (PS) microdots on mica. The PS dots were released from the mica in water. The release was affected by the density of K(+) ions on the mica surface, which was controlled by pretreatment with K(2)CO(3) solutions. The release of PS dots became dominant at the concentrations above [K(+)]crit = 1 x 10(-4) M in the K(2)CO(3) solution. In this concentration region, repulsive forces appeared as a result of the hydration of K(+) ions on the mica (J. Colloid Interface Sci. 1981, 83, 531). This result suggests that the repulsive hydration force causes the release of the PS dots. Followed by the release process, we successfully demonstrated the transfer of the array of PS dots from the mica to another substrate.