Inclusion Complex Formation of Thiacalix[4]arene and Xe in Aqueous Solution Studied by Hyperpolarized 129Xe NMR

The inclusion complex formation of 4-sulfothiacalix[4]arene sodium salt (STCAS) and Xe has been investigated by using hyperpolarized ¹²⁹Xe NMR spectroscopy. Our new continuous-flow type hyperpolarizing system has advantageous capabilities that can supply hyperpolarized gases continuously and directly to a sample solution in a NMR tube. Consequently saturated Xe concentration in the aqueous solution of STCAS is maintained during the NMR experiment, and ¹²⁹Xe NMR spectra can be obtained in remarkably short time. STCAS concentration dependence of ¹²⁹Xe chemical shift has been analyzed in an elaborated way by a computer method as well as a simple graphic method that we have proposed. The association constant K:13.6±0.8 M⁻¹ at 25 °C was obtained, and further analysis of the temperature dependence has successfully given thermodynamic parameters of enthalpy (ΔH) and entropy (ΔS) for the inclusion complex formation: ΔH = −11.9±1.9 kJ mol⁻¹ and ΔS = −17.4±5.8 JK⁻¹ mol⁻¹. The energetic aspects of complex formation are discussed from the size effect and from the molecular theory of standard entropy, and a release of definite number of water molecules from STCAS cavity is suggested in the inclusion complex formation with Xe.     

Determination of ammonium in river water and sewage samples by capillary zone electrophoresis with direct UV detection

We developed capillary zone electrophoresis (CZE) with direct UV detection for determination of ammonium in environmental water samples. Ammonium in the samples was partly converted into ammonia in the alkaline background electrolyte (BGE) during migration and was detected by molecular absorption of ammonia at 190 nm in approximately 7 min. The limit of detection (LOD) for ammonium was 0.24 mg/l (as nitrogen) at a signal-to-noise ratio of three. The respective values of the relative standard deviation (RSD) of peak area, peak height, and migration time for ammonium were 2.1, 1.8, and 0.46%. Major alkali and alkaline earth metal ions coexisting in the samples did not interfere with ammonium determination by the proposed method. The proposed method determined ammonium in surface water and sewage samples. The results were compared to those obtained using ion chromatography (IC).     

Characterization of amorphous hydrogenated carbon formed by low-pressure inductively coupled plasma enhanced chemical vapor deposition using multiple low-inductance antenna units

Three-dimensional plasma enhanced chemical vapor deposition (CVD) of hydrogenated amorphous carbon (a-C:H) has been demonstrated using a new type high-density volumetric plasma source with multiple low-inductance antenna system. The plasma density in the volume of phi 200 mm x 100 mm is 5.1 x 10(10) cm(-3) within +/-5% in the lateral directions and 5.2 x 10(10)cm(-3) within +/-10% in the axial direction for argon plasma under the pressure of 0.1 Pa and the total power as low as 400 W. The uniformity of the thickness and refractive index is within +/-3.5% and +/-1%, respectively, for the a-C:H films deposited on the substrates placed on the six side walls, the top of the phi 60 mm x 80 mm hexagonal substrate holder in the pure toluene plasma under the pressure is as low as 0.04 Pa, and the total power is as low as 300 W. It is also found that precisely controlled ion bombardment by pulse biasing led to the explicit observation in Raman and IR spectra of the transition from polymer-like structure to diamond-like structure accompanied by dehydrogenation due to ion bombardment. Moreover, it is also concluded that the pulse biasing technique is effective for stress reduction without a significant degradation of hardness. The stress of 0.6 GPa and the hardness of 15 GPa have been obtained for 2.0 microm thick films deposited with the optimized deposition conditions. The films are durable for the tribology test with a high load of 20 N up to more than 20,000 cycles, showing the specific wear rate and the friction coefficient were 1.2 x 10(-7) mm3/Nm and 0.04, respectively.     

Local crystal structure of nano-manganese-oxide gold adsorbent

The local crystal structure of dried and deuterated nano-manganese-oxide powder samples was studied via atomic pair distribution function analysis of X-ray and neutron powder diffraction data. The protonated sample shows ultrahigh efficiency as a gold adsorbent even from ppt-level aqueous solutions such as seawater. We show that the nano-manganese-oxide particles have an R-MnO₂-type local crystal structure. The possible role of the protons on the surface of the nano-particles is discussed.     

Analysis of labor productivity using large-scale data of firm’s financial statements

We investigated labor productivity distribution by analyzing large-scale financial statement data consisting of listed and unlisted Japanese firms to clarify the characteristics of the Japanese labor market. Both high and low productivity sides of the labor productivity distribution follows the power-law distribution. Large inequality in the low productivity side was observed only for the manufacturing sectors in Japan fiscal year (JFY) 1999 and observed for both the manufacturing and non-manufacturing sectors in JFY 2002. The decline in the Japanese GDP in JFY 1999 and JFY 2002 were coincided with the large inequality in the low productivity side of the distribution. A lower peak was found for all non-manufacturing sectors. This might be the origin of the low productivity of the non-manufacturing sectors reported in recent economic studies.     

Quantum Emulation of Extreme Non‐Equilibrium Phenomena with Trapped Atoms

Ultracold atomic physics experiments offer a nearly ideal context for the investigation of quantum systems far from equilibrium. We describe three related emerging directions of research into extreme non‐equilibrium phenomena in atom traps: quantum emulation of ultrafast atom‐light interactions, coherent phasonic spectroscopy in tunable quasicrystals, and realization of Floquet matter in strongly‐driven lattice systems. We show that all three should enable quantum emulation in parameter regimes inaccessible in solid‐state experiments, facilitating a complementary approach to open problems in non‐equilibrium condensed matter.     

A new approach of direct sample-digestion before vaporization for determination of a metal in rocks by inductively coupled plasma atomic emission spectrometry.

A new approach to sample digestion, subsequent vaporization and introduction to an inductively coupled plasma (ICP) atomic emission spectrometer was developed for the direct determination of magnesium. To each small sample cuvette made of tungsten, a ground rock sample was precisely weighed. The cuvette was situated on a tungsten boat furnace. Ammonium fluoride solution was added to the cuvette as a chemical modifier. After the on-furnace digestion has been completed, the analyte, magnesium, in the cuvette was vaporized and introduced into the ICP atomic emission spectrometer. Since the powdered samples were wet-digested in the sample cuvettes prior to vaporization, they could be analyzed by using a calibration curve prepared from aqueous standard solutions. This method was applied to the determination of magnesium in several standard reference materials with satisfactory results.