Trace analysis of high-purity copper by total reflection X-ray fluorescence spectrometry

Total reflection X-ray fluorescence (TXRF) analysis after the separation of matrix element was studied for the determination of trace impurity elements (Ca, Sc, V, Cr, Mn, Fe, Co, Ni and Zn) in high purity copper. Matrix copper was removed by electrolysis (0.2 A, 8 h) of a nitric acid solution. A 10 μL aliquot of the remaining solution of the electrolysis was dropped on a silicon-wafer sample-carrier and dried in a vacuum. This was repeated five times and the precipitate of five 10 μL-aliquots was analyzed by TXRF using a W-Lβ beam with an incident angle of 0.05 °. TXRF analytical values were obtained by using relative sensitivity factors of the analytes to the internal standard element (Pd). Detection limits of the analytes ranges from 0.077 ng for Zn to 0.785 ng for Ca. Received: 25 December 1997 / Revised: 30 March 1998 / Accepted: 2 April 1998     

On some properties of the ε-core of games with coalition structure

Chang [1991] stated some inclusion relation about kernel, reasonable set, and ε-core of games with coalition structure. We give counterexamples and modify erroneous results. Received: May 1997/Revised version: January 1999     

Demonstration of highly efficient broadband amplification in a optical parametric chirped-pulse amplifier system

We have demonstrated highly efficient broadband amplification by an optical parametric chirped pulse amplifier (OPCPA) system that uses high energy seed pulses. The OPCPA consists of three type I B-barium borate (BBO) crystals pumped by a Q-switched Nd:YAG laser. We successfully amplified the microjoule level seed pulses to 78 mJ with a pump-to-signal optical conversion efficiency of 26% at a 10 Hz repetition rate. To our knowledge these results represent the most optically efficient OPCPA to date pumped by a typical Q-switched laser.     

Self-assembled monolayer and multilayer formation using redox-active Ru complex with phosphonic acids on silicon oxide surface

The formation of self-assembled monolayer and multilayer using redox-active Ru complex molecules with phosphonic acids on SiO₂ surface has been examined using X-ray photoelectron spectroscopy (XPS), ellipsometry, and time of flight secondary mass-ion spectroscopy (TOF-SIMS). We found that an introduction of a Zr adlayer leads to higher surface molecular density of Ru complex SAMs on the SiO₂ surface, compared to that of obtained from the direct adsorption of Ru complex monolayer on the SiO₂ surface. We further tried to fabricate a multilayer film using this molecule with Zr(IV) ion acting as a chemical glue by a successive immersion process. The XPS data revealed that the molecular densities of the multilayers were also higher for the immobilization with Zr adlayer between Ru complex and SiO₂ surface than those without the Zr adlayer, suggesting that Zr adlayer is effective in forming highly packed molecular layer of phosphonic acids on SiO₂ surface. We found the film growth reached a saturation point after 6 layers on the SiO₂ surface. The film growth saturation can be explained by a molecular domain boundary effect encountered due to the large tilt angle of the molecular layer.     

Nonexistence of Kirkwood's instability in a uniform fluid

Kirkwood's instability in the theory of fluid-solid transitions is proved to be impossible. Fluctuation of the one-particle distribution function in the first equation of the BGY hierarchy is investigated beyond Kunkin and Frisch's treatment. The second equation of the BGY hierarchy is utilized to eliminate the three-particle distribution function left in the Kunkin-Frisch result. The final expression for the first-order fluctuation of the one-particle distribution function under the presence of an external field is written in a form including only the pair correlation function and agrees identically with the one obtained from the direct expansion of the oneparticle distribution function in terms of the external field.     

Generation of high-contrast and high-intensity laser pulses using an OPCPA preamplifier in a double CPA, Ti:sapphire laser system

We demonstrate a high-contrast, high-intensity double chirped-pulse amplification (CPA) Ti:sapphire laser system using an optical parametric chirped-pulse (OPCPA) pre- amplifier. By injecting cleaned microjoule seed pulses into the OPCPA, a temporal contrast greater than 10¹⁰ within picosecond times before the main femtosecond pulse is demonstrated with an output pulse energy of 1.7 J and a pulse duration of 30 fs, corresponding to a peak power of 60 TW at a 10 Hz repetition rate. This system uses a cryogenically-cooled Ti:sapphire final amplifier and generates focused peak intensities in excess of 10²⁰ W/cm².     

Thermal decomposition and carbonization mechanism of poly-para-phenyleneoxadiazole

Thermal decomposition and carbonization mechanism of poly-para-phenylene-1,3,4-oxadiazole were investigated using FT-IR, thermogravimetry, gas-analysis, XPS, ¹³C-CP/MASFT-NMR, and elemental analysis. At temperatures above 500°C, the decomposition reaction proceeds preferentially on the oxadiazole ring, eliminating p-aminocyanobenzene and p-dicyanobenzene. Formation of carbodiimide compounds and their coupling followed in residual compounds, whose products are important intermediates leading to a planar and polyconjugated nitrogen-containing (e.g., graphite-like) carbon precursor.     

BEHAVIORAL RESPONSES IN Paramecium multimicronucleatum TO VISIBLE LIGHT

Specimens of colorless Paramecium multimicronucleatum were found to respond to visible light. They accumulated in the shaded region (photodispersal) of a half-shaded glass tube during 2 min exposure to visible light. The specimens showed avoiding reaction upon both spatial and temporal increase in light intensity (step-up photophobic response). Steady-state swimming velocity (orthokinesis) was higher, while steady-state frequency of spontaneous change in swimming direction (klinokinesis) was lower when the light intensity was kept higher. In a light with wavelength of 440 nm the velocity was highest, while the frequency was lowest. The specimens did not show phototaxis (light direction-oriented locomotion). Spectral sensitivity curves for both the photodispersal and the step-up photophobic response showed a major peak at 520 nm and a minor peak at 680 nm. The photodispersal seems to be caused mainly by the step-up photophobic response exhibited by the specimens at the dark-light border. The photokinetic responses enhance the degree of the photodispersal.     

Symmetric submanifolds associated with irreducible symmetric R-spaces

We construct examples of symmetric submanifolds in Riemannian symmetric spaces of noncompact type and obtain the classification of symmetric submanifolds in irreducible Riemannian symmetric spaces of noncompact type and rank greater than one. This finishes the classification problem of symmetric submanifolds in Riemannian symmetric spaces completely.