Dehydrogenation reaction for Na-O-H system: a first-principles study.

The crystal structures, electronic, dielectric, and vibrational properties of NaH, Na(2)O and NaOH are systematically investigated by first-principles calculations and the quasiharmonic approximation. The phonon dispersion relations and the phonon density of states of the phases and their thermodynamic functions including the heat capacity, the vibrational enthalpy, and the vibrational entropy are calculated using a direct force-constant method. Based on these results, the dehydrogenation reaction, NaH+NaOH-->H(2)+Na(2)O, is predicted to take place at 528 K, which is in agreement with the experimental observed value.     

Optimization of Fe/SiO<Subscript>2</Subscript> based metal oxides as selective oxidation catalyst of propane with combinatorial approach

A combinatorial optimization with genetic algorism was performed on the five generations of 0.05 atm% Fe/SiO₂ added multi-metal oxides to be used as catalytic materials for the selective oxidation of propane to give aldehydes at 623-773 K. The loaded multi-metal oxides consist of some elements selected from seven elements with various atomic charges or redox properties. For the best materials, selectivity toward aldehydes from 35% at 1st generation to 45% at 4th generation were achieved at 5% propane conversion. Further rational optimization of the best performance catalyst also improves the selectivity up to 49.5%.     

Tris(1,10‐phenanthroline‐N,N′)­iron(II) di­thio­cyanate tri­hydrate

The title mononuclear iron(II) complex, [Fe(C₁₂H₈N₂)₃](NCS)₂·3H₂O, has a slightly distorted octa­hedral coordination. One of the thio­cyanate ions and one of the water mol­ecules of crystallization show positional disorder.     

Electrochemical etching process to tune the diameter of arrayed deep pores by controlling carrier collection at a semiconductor–electrolyte interface

An approach to control the diameter of high-aspect-ratio pores formed into a silicon wafer by an electrochemical etching process is reported. Hole (h⁺) was involved in the etching reaction and the collection of the h⁺ was the key factor. Artificial micro-cavities were fabricated on the silicon surface prior to the etching. The depth of the space charge region (SCR), Schottky barrier on the silicon-electrolyte interface, was adjusted regarding the depth of the micro-cavities by applied overpotential and specific resistance of the silicon wafer. The collection of h⁺ at the tip of the cavity site was widely controlled by the adjusted SCR. Consequently the electrochemically etched domain at the cavity site was actively tuned, and then high-aspect-ratio pore with the controlled diameter was formed. The diameter was tuned by the SCR depth which was controlled by the overpotential and the specific resistance. The diameter tuning mechanism worked under the mask-free condition.     

Anisotropic polymerization of a long-chain diacetylene derivative Langmuir-Blodgett film on a step-bunched SiO2/Si surface

Alternating facet/terrace nanostructures were fabricated on a SiO2 surface by step-bunching and thermal oxidation of a vicinal Si(111) substrate, and their influence upon the polymerization direction of a long-chain diacetylene derivative monolayer film was investigated by angle-dependent polarized near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. It was found that the peak intensity of the C 1s-pi transition was stronger when the electric vector plane of the incident X-ray was parallel to the direction of the periodic facet/terrace structures rather than perpendicular to them. On the contrary, a polymer film fabricated on a flat SiO2 surface showed no in-plane anisotropy of the peak intensity. These results indicate that the diacetylene groups in the diacetylene derivative monolayer are preferentially photopolymerized in the direction not across but along the periodic one-dimensional structures on the step-bunched and thermally oxidized SiO2/Si(111) surface.     

Mechanisms of Incipient Chemical Reaction between Ca(OH)2and SiO2under Moderate Mechanical Stressing

The structure of mechanically induced precursor in an amorphous state between Ca(OH)₂and SiO₂was determined by solid state MAS and CP/MAS²⁹SiNMR spectroscopies, and the changes in the behavior of crystallization by linear heating were studied by X-ray diffractometry. A large broad Q₀peak due to the short-range order of hydrated calcium silicates appeared in the²⁹SiNMR spectra of mechanically induced precursors. The formation of the new ordering is confined in the near-surface region of SiO₂particles, as confirmed by comparing MAS and CP/MASNMR spectra. When the amorphous precursor obtained above was subsequently heated, a rapid solid state reaction led to single phasedα-CaSiO₃as the final product.     

Penems. I. Novel synthesis of antibacterial penem compounds utilizing 1,3-dithiolane derivatives

A novel penem synthesis utilizing 1,3-dithiolane or 1,3-dithiane derivatives allowed us to synthesize a number of new antibacterial penem compounds.     

Strongly Incompatible Quantum Devices

The fact that there are quantum observables without a simultaneous measurement is one of the fundamental characteristics of quantum mechanics. In this work we expand the concept of joint measurability to all kinds of possible measurement devices, and we call this relation compatibility. Two devices are incompatible if they cannot be implemented as parts of a single measurement setup. We introduce also a more stringent notion of incompatibility, strong incompatibility. Both incompatibility and strong incompatibility are rigorously characterized and their difference is demonstrated by examples.