Nature of the well screened state in hard X-ray Mn 2p core-level photoemission measurements of La1-xSrxMnO3 films

Using hard x-ray (HX; hnu=5.95 keV) synchrotron photoemission spectroscopy (PES), we study the intrinsic electronic structure of La(1-x)Sr(x)MnO(3) (LSMO) thin films. Comparison of Mn 2p core-levels with soft x-ray (SX; hnu approximately 1000 eV) PES shows a clear additional well-screened feature only in HX PES. Takeoff-angle dependent data indicate its bulk (> or =20 A) character. The doping and temperature dependence track the ferromagnetism and metallicity of the LSMO series. Cluster model calculations including charge transfer from doping-induced states show good agreement, confirming this picture of bulk properties reflected in Mn 2p core-levels using HX PES.     

Chiral phosphinooxazolidine ligands for palladium- and platinum-catalyzed asymmetric Diels-Alder reactions

Cationic palladium (Pd)- and platinum (Pt)-phosphinooxazolidine catalysts 13a-c, 15a-d, 17a-c, and 19a-c were prepared from phosphinooxazolidine ligands 1-3, MCl(2) (M = Pd and Pt), and counterions, and the activities of the catalysts in the asymmetric Diels-Alder (DA) reactions of cyclic or acyclic dienes with imide dienophiles were investigated. These catalysts demonstrated high levels of catalytic activity. The cationic Pd-POZ complex 13c provided particularly excellent enantioselectivity (98% ee) in the DA reactions of cyclopentadiene with acryloyl-, crotonyl-, and fumaroyl-1,3-oxazolidin-2-ones (20a-c).     

Iodine atom transfer [3 + 2] cycloaddition reaction with electron-rich alkenes using N-tosyliodoaziridine derivatives as novel azahomoallyl radical precursors

Treatment of N-tosyliodoaziridine derivatives with Et(3)B efficiently produces various azahomoallyl radical (2-akenylamidyl radical) species which give oxygen-functionalized pyrrolidine derivatives through iodine atom transfer [3 + 2] cycloaddition with electron-rich alkenes such as enol ethers and ketene acetal. The present cycloaddition reaction proceeds regioselectively via C-N bond cleavage of an aziridinylalkyl radical intermediate and addition of the resulting azahomoallyl radicals to the terminal carbon of an alkene. The reaction of alkenes with the cyclohexenylamidyl radical generated from an optically active bicyclic iodoaziridine [(1S,2S,6S)-2-iodo-7-(p-toluenesulfonyl)-7-azabicyclo[4.1.0]heptane, 94% ee] also proceeds to give optically active octahydroindole derivatives (84-93% ee).     

Superconducting gap anisotropy in Nd1.85Ce0.15CuO4: results from photoemission

We have performed angle resolved photoelectron spectroscopy on the electron doped cuprate superconductor Nd1.85Ce0.15CuO4. A comparison of the leading edge midpoints between the superconducting and normal states reveals a small, but finite shift of 1.5-2 meV near the ( pi,0) position, but no observable shift along the zone diagonal near ( pi/2, pi/2). This is interpreted as evidence for an anisotropic superconducting gap in the electron doped materials, which is consistent with the presence of d-wave superconducting order in this cuprate superconductor.     

On the Eigenstates of the Elliptic Calogero–Moser Model

It is known that the trigonometric Calogero–Sutherland model is obtained by the trigonometric limit (–1) of the elliptic Calogero–Moser model, where (1, ) is a basic period of the elliptic function. We show that for all square-integrable eigenstates and eigenvalues of the Hamiltonian of the Calogero–Sutherland model, if exp(2–1) is small enough then there exist square-integrable eigenstates and eigenvalues of the Hamiltonian of the elliptic Calogero–Moser model which converge to the ones of the Calogero–Sutherland model for the 2-particle and the coupling constant l is positive integer cases and the 3-particle and l=1 case. In other words, we justify the regular perturbation with respect to the parameter exp(2–1). With some assumptions, we show analogous results for N-particle and l is positive integer cases.     

Time‐resolved x‐ray fluorescence for monitoring the intake of mineral nutrients in living plants

We have applied a time‐resolved means of measurement for studying living plants. The intake of mineral nutrients in a living plant such as stevia has been observed by this measuring instrument. A solution containing K, Ca, Mn, Fe, Cu, and Zn compounds was used as the mineral nutrient solution. The concentrations of the standard solutions were specifically chosen to obtain optimal intensities of the x‐ray peaks. The time dependence of the x‐ray fluorescence (XRF) intensity showed specific intake processes depending on the type of element. In addition, the experimental results suggest differences in the translocation of each element in the stevia stem. We conclude that time‐resolved XRF is a powerful technique for studying living plants. Copyright © 2007 John Wiley & Sons, Ltd.     

DFT studies of ESR parameters for N?O centered radicals,N‐alkoxyaminyl and aminoxyl radicals

Theoretical calculations of ESR parameters for aminoxyl radicals have been widely studied using the density functional theory (DFT) calculations. However, the isomer N‐alkoxyaminyl radicals have been limitedly studied. With the use of experimental data for 46 N‐alkoxyaminyl and 38 aminoxyl radicals, the isotropic ¹⁴N hyperfine coupling constants (a_N) and g‐factors have been theoretically estimated by several DFT calculations. The best calculation scheme of a_N for N‐alkoxyaminyl radicals was PCM/B3LYP/6‐31 + + G(d,p) (R² = 0.9519, MAE = 0.034 mT), and that for aminoxyl radicals was PCM/BHandHLYP/6‐31 + + G(3df,3pd) (R² = 0.9336, MAE = 0.057 mT). For aminoxyl radicals, the solvation models in calculations enhanced the accuracy of reproducibility. In contrast, for N‐alkoxyaminyl radicals the calculations with solvation models provided no improvement. The differences in the best functionals between two types of radicals were thought to come from the contribution ratios of neutral and dipolar canonical structures in resonance forms. The a_N for N‐alkoxyaminyl radicals that were stabilized by small contribution of dipolar canonical structures could be precisely reproduced by B3LYP with only 20% HF exact exchange. In contrast, the a_N for aminoxyl radicals stabilized by large contribution of dipolar canonical structures was well reproduced by BHandHLYP with 50% HF exchange. The best calculation scheme of g‐factors was IEFPCM/B3LYP/6‐31 + G(d,p) (R² = 0.9767, MAE = 0.0001) for not only aminoxyl but also N‐alkoxyaminyl radicals. Copyright © 2011 John Wiley & Sons, Ltd.     

Thermal decomposition of butylindium thiolates and preparation of indium sulfide powders

Thermal properties of organoindium thiolates were investigated by means of thermogravimetric (TG) and differential thermal (DT) analysis. Dibutyl-indium propylthiolates (Buⁿ₂InSPrⁿ, Buⁿ₂InSPrⁱ, Buⁱ₂InSPrⁿ and Buⁱ₂InSPrⁱ) decomposed up to 280°C along with an exothermic DT peak and gave indium(I) sulfide (InS) powders. Although the arylthiolate Buⁿ₂InSPh also afforded InS powders, it decomposed at a slightly higher temperature. In contrast, the dithiolate and the dithiocarbamate complexes [BuⁿIn(SPrⁱ)₂ and In (S₂CNBu₂)₃] gave indium(III) sulfide (In₂S₃) powders.     

Application of a coated-wire electrode to an acetylcholine sensor

An acetylcholine sensor was constructed with acetylcholinesterase which was immobilized on a hydrogen ion-selective coated-wire electrode and fundamental properties of this sensor were investigated. Acetylcholine could be determined in the range 0.1–10 rum with response times of 3–10 min. The effects of pH and concentration of buffer solution on the determination and fluctuations in the data obtained with this sensor were also investigated. Possibilities for the practical use of this acetylcholine micro-sensor are suggested.     

Oxygen-assisted shape control in polyol synthesis of silver nanocrystals

We have found that the shape of silver nanocrystals is conveniently controlled by injection of oxygen gas during the polyol reduction of silver ions. The presence of oxygen effectively promotes the oxidative etching of multiple twined particles. Adjusting the flow rate of the oxygen gas yields uniformly-sized silver nanocubes, right bipyramids, nanowires, and spherical nanoparticles depending on the injection rate of the oxygen gas. Electron diffraction and high resolution TEM observations of the synthesized nanocrystals show our nanocrystals do consist of silver, not of silver oxide. SERS activities of the synthesized nanocrystals were also examined.