Characteristic energy band values and electron attenuation length of a chemical-vapor-deposition diamond (0 0 1)2 × 1 surface

The characteristic energy band values such as the Fermi-level position with respect to valence band top for a boron-doped p-type hydrogen-terminated chemical-vapor-deposition (CVD) diamond (0 0 1)2 × 1 surface and for a clean CVD diamond (0 0 1)2 × 1 surface have been determined by a new method with an accuracy of ±0.02 eV. The electron attenuation length for the clean diamond (0 0 1)2 × 1 surface for the electron kinetic energy of C 1s X-ray photoemission peak by Mg Kα excitation is experimentally determined to be 2.1-2.2 nm. These values are compared and discussed with the previously reported experimental and simulation values.     

Analysis of phase transition behavior of BaCeO3 with thermal analyses and high temperature X-ray diffraction

Structural phase transitions in BaCeO₃ have been investigated with combination of differential scanning calorimetry (DSC), dilatometry and high temperature X-ray diffraction with high sensitivity and resolution. In DSC curve at heating procedures, baseline shift, endothermic peak and another baseline shift were observed at 260 °C, 385 °C and 895 °C, respectively. From DSC curve at cooling procedure, it was revealed that all the baseline shifts and peak were reversible. No hysteresis was observed in the both baseline shifts indicating second order phase transition at 260 °C and 895 °C with variation of specific heat capacity, ΔC_p, of 10 J/mol K and 7 J/mol K, respectively; whereas the order of the phase transition at 385 °C was revealed to be the first since hysteresis was detected around 370–385 °C. Variation of enthalpy, ΔH, at the phase transition was 45 J/mol. High temperature X-ray diffraction measurements have revealed that the crystal structure of BaCeO₃ changes from primitive orthorhombic perovskite through body-centered one, rhombohedral distorted one to cubic one around 280 °C, 400 °C and 900 °C, showing correspondence with DSC curves. Dependence of molar volume on temperature estimated from high temperature X-ray diffraction showed agreement with thermal expansion behavior observed with dilatometry.     

Improvement of depth resolution in XPS analysis of fluorinated layer using C60 ion sputtering

Depth profile of C₆₀ ion-used X-ray photoelectron spectroscopy (XPS) was studied on fluorinated organic layers with different thicknesses. We found that the depth resolution decreased, the sputtering rate went down and the surface turned rough as the layer thickness increased. This is because carbon-rich layer was formed on the surface by cross-linking reaction of the polymer and/or accumulation of degraded C₆₀ through continuous sputtering. Surprisingly, the high sputtering rate drastically improved the resolution of the analysis. The rate over 48.7 nm/min did not show any deterioration on the depth resolution, the sputtering rate and surface smoothness.     

Experimental Discussion on Eye-Safe 1.54 μm Photon Counting Lidar Using Avalanche Photodiode

A Mie hdar system with an eye-safe wavelength of 1.54 m was developed and its performance characteristics were experimentally discussed. The wavelength was generated by a Nd:YAG based methane-shifted Raman laser. The collected backscattering light was detected by an InGaAs avalanche photodiode working in photon counting mode at that wavelength. Results of atmospheric observation showed clearly the dynamics of multi-layered cluds up to an altitude of 7 km. The systems performance was confirmed on the point of signal to noise ratio in both the observation and the simulation. Advantages of the eye-safe 1.54 m wavelength in lidar atmospheric research and system limitations were discussed. © 2004 The Optical Society of Japan     

A dodecameric porphyrin wheel

A dodecameric porphyrin wheel was prepared by Ag(I)-promoted intramolecular coupling of a linear porphyrin dodecamer and was observed by scanning tunneling microscopy (STM). Efficient energy hopping along the array was revealed by femtosecond transient anisotropy measurements.     

Punishment strategies make the α-coalitional game ordinally convex and balanced

We present a sufficient condition under which the -coalitional game associated with a strategic form game is ordinally convex and balanced. The n-person prisoners dilemma games satisfy this condition.The author is grateful to Mikio Nakayama, Yukihisa Utsumi, William Thomson, an anonymous referee and an associate editor for helpful comments and suggestions.     

Synthesis of a bis(pyridyl)-substituted perylene diimide ligand and incorporation into a supramolecular rhomboid and rectangle via coordination driven self-assembly

The synthesis of a bis(pyridyl)-substituted perylene diimide ligand and its incorporation into a supramolecular rhomboid and rectangle via platinum-mediated self-assembly is reported. Both ensembles are characterized by multinuclear NMR and electrospray ionization mass spectrometry. In addition, the UV/vis spectra of the ensembles exhibit displaced and enhanced absorptions relative to the starting ligand. Size estimations using MM2 simulations show the assemblies are almost 46 A in length.     

Inhibition of cytopathic effect of human immunodeficiency virus type-1 by various phorbol derivatives

Forty-eight derivatives of phorbol (9) and isophorbol (14) were evaluated for their inhibition of human immunodeficiency virus (HIV)-1 induced cytopathic effects (CPE) on MT-4 cells, as well as their activation of protein kinase C (PKC), as indices of anti-HIV-1 and tumor promoting activities, respectively. Of these compounds, the most potent inhibition of CPE was observed in 12-O-tetradecanoylphorbol 13-acetate (8) and 12-O-acetylphorbol 13-decanoate (6). The former also showed the strongest PKC activation activity, while the latter showed no activity at 10 ng/ml. Both activities were generally observed in those phorbol derivatives with an A/B trans configuration, but not in the isophorbol derivatives with an A/B cis configuration. Acetylation of 20-OH in the phorbol derivatives significantly reduced the inhibition of CPE, as shown in 12-O-, 20-O-diacetylphorbol 13-decanoate (6a) (IC100=15.6 microg/ml) vs. compound 6 (IC100=0.0076 microg/ml), and 12-O-tetradecanoylphorbol 13,20-diacetate (8a) (IC100=15.6 microg/ml) vs. 12-O-tetradecanoylphorbol 13-acetate (8) (IC100=0.00048 microg/ml), except in the case of 12-O-decanoylphorbol 13-(2-methylbutyrate) (4) and phorbol 12,13-diacetate (9c). The reduction of a carbonyl group at C-3 abruptly reduced the inhibition of CPE, as observed in 3beta-hydroxyphorbol 12,13,20-triacetate (9f) (IC100=500 microg/ml) vs. phorbol 12,13,20-triacetate (9d) (IC100=62.5 microg/ml). Although 8 was equipotent in the inhibition of CPE, and activation of PKC, both activities were abruptly decreased by the acetylation of 20-OH and methylation of 4-OH [as in 8a and 4-O-methyl-12-O-tetradecanoylphorbol 13,20-diacetate (8b), respectively]. On the other hand, its positional isomer (12-O-acetylphorbol 13-tetradecanoate (8c) showed neither activities. The removal of a long acyl group in 8 led to a substantial loss of both activities, as shown in phorbol 13-acetate (9b). Of the 12-O-acetyl-13-O-acylphorbol derivatives, the highest inhibition of CPE was observed in 6, which has a dodecanoyl residue at C-13. Both an increase and decrease in the number of fatty acid carbon chains resulted in significant reduction of the inhibition of CPE.