Self-alignment of Co adatoms on in atomic wires by quasi-one-dimensional electron-gas-meditated interactions

Low-density Co atoms are found to self-align on the Si(111)-(4 x 1)-In surface in the direction of In atomic wires at incommensurate adsorption sites. Indirect interaction between a pair of Co adatoms is investigated through a site distribution function of adatoms determined with scanning tunneling microscopy. In the direction of self-alignment, the potential of the mean force between two Co adatoms is long-range and oscillatory with multiple frequencies, which correlate strongly to the electronic scattering vectors of the surface-state bands at the Fermi level. We thus attribute the Co-Co interaction to that mediated by a quasi-one-dimensional electron gas confined within the In atomic wires.     

Double Ring Expansion from an Aromatic [18]Porphyrin(1.1.1.1) to an Antiaromatic [20]Porphyrin(2.1.2.1)

Double ring expansion from a 5,15‐diarylporphyrin to a 5,16‐diaryl‐10,11,21,22‐tetradehydro[20]porphyrin(2.1.2.1) occurred through a reaction sequence consisting of oxidation with PbO₂ to 5,15‐dioxoporphodimethene, a Corey–Fuchs reaction with tetrabromomethane in the presence of triphenylphosphine, and Fritsch–Buttenberg–Wiechell rearrangement triggered by tert‐butyllithium. The obtained tetradehydro[20]porphyrin(2.1.2.1) and its mono‐ and dihydrogenated congeners exhibited 20 π antiaromatic character, whereas overhydrogenated congeners bearing a saturated bridge were nonaromatic owing to disrupted π conjugation.     

A single-dipole model of surface relief grating formation on azobenzene polymer films

A new model that keeps track of the dynamics of single dipoles is suggested for the photoinduced formation of a surface relief grating on azobenzene polymer films by two optical fields. Interfering optical fields provide a single dipole of an azobenzene molecule with two dynamical resources: rotation of the molecule caused by the torque, leading to an induced dipole, and its subsequent migration because of the electric force. Explicit development of the induced dipole of the molecule and its real-time migration, which depend on the details of the optical fields such as polarization and wavelength, can be understood self-consistently within the model.     

A multigrid‐based shifted Laplacian preconditioner for a fourth‐order Helmholtz discretization

In this paper, an iterative solution method for a fourth‐order accurate discretization of the Helmholtz equation is presented. The method is a generalization of that presented in (SIAM J. Sci. Comput. 2006; 27 :1471–1492), where multigrid was employed as a preconditioner for a Krylov subspace iterative method. The multigrid preconditioner is based on the solution of a second Helmholtz operator with a complex‐valued shift. In particular, we compare preconditioners based on a point‐wise Jacobi smoother with those using an ILU(0) smoother, we compare using the prolongation operator developed by de Zeeuw in (J. Comput. Appl. Math. 1990; 33 :1–27) with interpolation operators based on algebraic multigrid principles, and we compare the performance of the Krylov subspace method Bi‐conjugate gradient stabilized with the recently introduced induced dimension reduction method, IDR(s). These three improvements are combined to yield an efficient solver for heterogeneous problems. Copyright © 2009 John Wiley & Sons, Ltd.     

Cu2+ -mediated assembly of the minor groove binders on the DNA template with sequence selectivity

The ligands (Bpy-H, 5) have been designed to connect the Hoechst33258 skeleton for DNA binding and 2,2'-bipyridine for Cu(2+) complexation. It has been revealed that the new Hoechst ligand long Bpy-H (5L) having a long linker exhibits Cu(2+)-mediated assembly on the DNA template having two A(3)T(3) sites in a selective manner depending on the length of the linker of the ligand as well as on the distance between the two A(3)T(3) sites of DNA. [reaction: see text]     

Evaluation of a radioimmunoassay of alpha 1-microglobulin (alpha 1-m) with simplified procedures

A newly established double antibody radioimmunoassay (RIA) was fundamentally and clinically evaluated. Original procedures were partially modified as follows: Sample volume for serum and urine was changed to 25 microliters, and thus 200 mg/l of alpha 1-m standard was prepared using 50 microliters of original standard solution (100 mg/l). The results were satisfactory in sensitivity (0.3 mg/l obtained from -2SD method), intra-assay precision with its coefficient variation (CV) ranging from 3.0 to 7.4%, interassay precision with its CV ranging from 3.0 to 10.7%, and recovery with the mean value of 102.4% in serum and 108.2% in urine respectively. There were no changes about alpha 1-m value between diluted (2 times) and undiluted with high concentration samples. Normal levels of alpha 1-m were less than 25 mg/l in serum and less than 10 mg/l in urine. The present results indicate that the determination of alpha 1-m could be very simple and useful for the most sensitive screening test for the evaluation of renal function.     

Synergic liquid/liquid extraction of lithium and sodium with 4-acyl-5-pyrazolones with bulky substituents and tri-n-octylphosphine oxide

The synergic liquid/liquid extraction of lithium and sodium with 4-acyl-5-pyrazolones having bulky substituents and tri-n-octylphosphine oxide (TOPO) is described. The maximum percentage extraction and the separation of lithium and sodium were improved by introducing bulky substituents. Quantitative extraction (? 99% ) of lithium could be achieved by adduct formation with TOPO, which enhanced the extraction much more than did triphenylphosphine oxide. The extraction decreased in the solvent order cyclohexane ? benzene ? chloroform, which is the general trend in synergic extractions.     

Solvent extraction of lithium and sodium with 4-benzoyl or 4-perfluoroacyl-5-pyrazolone and TOPO

The synergic solvent extraction of lithium and sodium into benzene or cyclohexane with 4-benzoyl or 4-perfluoroacyl-5-pyrazolone and trioctylphosphine oxide (TOPO) has been investigated. Quantitative extraction (>99%) of lithium, which is one of the most poorly extractable metal ions, can be achieved with 1-tolyl-3-methyl-4-perfluoroacyl-5-pyrazolone and TOPO. The extraction of sodium is somewhat poorer than that of lithium under the same conditions. The perfluoroacyl group at the 4-position of the pyrazolone ring enhances the extraction and increases the maximum percentage extracted. Cyclohexane is found to be suitable for a quantitative extraction as an organic phase when the reagents are soluble in it. Improved separation of lithium and sodium can be attained when they are extracted into benzene.     

Target thickness dependence of Kα X-ray energy shifts in 80 and 120 MeV Cu + Cu collisions

Energy shifts of target Kα x-rays in 80 and 120 MeV Cu + Cu collisions have been observed to vary 90–108 and 100–137 eV, respectively, in target thicknesses of 1–20 μg/cm² range where the projectile charge states change from nonequilibrium to equilibrium.