Demonstration for a two-axis interferometric tilt sensor in KAGRA

Recently, a folded Mach–Zehnder interferometer with homodyne in- and quadrature-phase detection was proposed as a high-precision, wide-dynamic range tilt sensor. By way of a practical application and to validate actual performance, two-axis tilt sensors were developed and installed for one mirror of the input mode cleaner cavity in KAGRA, the large-scale cryogenic gravitational-wave telescope in Kamioka, Gifu, Japan. Building on previous work, we have demonstrated that the two-axis tilt sensor has properly sensed the tilt angle changes of the mirror motion with high precision and without calibration. Compared with our initial angular sensor, an optical lever, which is calibrated by using the interferometer tilt sensor, we found that both sensors showed actual tilt motions of the mirror at low frequencies, and the two-axis interferometer sensor has a better sensitivity at higher frequencies.     

Interpretation of apparent chemical shifts in XP spectra from oxide—GaP interfaces

The cause of the apparent chemical shifts (ACS's) of XPS peaks between oxide and substrate GaP has been studied. The ACS's for Ga 3d, P 2p and GaLMM change significantly depending on the conditions of oxidation. The changes in the ACS's are considered in terms of not only the chemical structure of the oxide, but also other possible causes, such as charging effects, electric dipole moment, extra-atomic relaxation energy, Fermi-level pinning position, etc. The change of the Fermi-level position at the surface of substrate GaP is revealed to be a dominant factor causing the changes in the ACS's.     

Ion current generation in the field ion microscope: I. dynamic approach

The numbers of gas particles arriving at unit tip surface in unit time from a field free region are derived as functions of velocity components for a spherical tip. It is shown that a considerable fraction of the gas particles arrives at the tip having large tangential velocities. The simple model of collision of a particle with a metal surface is used and the trajectories and rebounds of particles are tracked. The principal method to calculate the total ion current is shown. The capture probability of particles by the dipole attraction potential is shown to increase when the tip temperature is lowered, the field strength is increased, the mass ratio of the gas atom to the metal atom increases and the gas temperature is lowered.     

Highly regio- and stereoselective ring-opening reaction of γ-alkenyl-γ-butyrolactones using allylsilanes-trimethyloxonium salt to afford methyl (e)-4,8-alkadienoates

γ-alkenyl-γ-butyrolactones reacted regio- and stereoselectively with allytrimethyl-silanes in the presence of tethyloxonium tetrafluoroborate to afford methyl (E)-4,8-alkadienoates in high yields. Synthetic utility of the present reaction was demonstrated by the synthesis of β-sinensal.     

Retro‐ene reactions in heterocyclic synthesis. v. a novel synthetic method for 1,3,5‐triazine‐2,4(1H,3H)‐diones

N‐t‐Butylamidines 1 on heating with diphenyl carbonate ( 2 ) at 150‐180° gave the 1,3,5‐triazine‐2,4(1H,3H)‐dione derivatives 5 . Acylation of amidines 1 and cyclocondensation of the resulting carbamates 3 gave [1,3,5,7]tetrazocine‐2,6‐dione derivatives 4 , and subsequent retro‐ene reaction and ring contraction afforded triazine derivatives 5 .     

Development of a column-switching high-performance liquid chromatography for kynurenine enantiomers and its application to a pharmacokinetic study in rat plasma

Kynurenine (KYN), a tryptophan metabolite, is a precursor of kynurenic acid, which is an antagonist of N-methyl-d-aspartate receptor. In this study, an enantiomeric separation of d,l-KYN derivatized with the benzofurazan fluorescence reagent 4-N,N-dimethylaminosulfonyl-7-fluoro-2,1,3-benzoxadiazole (DBD-F) (DBD-d,l-KYN) was first investigated by using a high-performance liquid chromatography (HPLC) with several chiral columns. As a consequence, DBD-d,l-KYN was enantiomerically separated on a cellulose-type chiral column (CHIRALCEL OJ-RH) with a mobile phase of H₂O/CH₃CN/MeOH (40/50/10) containing 0.1% acetic acid. Under this condition, the separation factor and resolution were 1.48 and 1.28, respectively. Next, a column-switching HPLC consisting of both octadecylsilica and chiral columns was developed and used to determine both d- and l-KYN enantiomers in 10 μL of rat plasma following the intraperitoneal administration of d,l-KYN to rats (10 mg kg⁻¹). The result revealed that the concentration of l-KYN was higher than that of d-KYN, suggesting that d-KYN was eliminated faster than l-KYN.     

Generation of Bis(ferrocenyl)silylenes from Siliranes

Divalent silicon species, the so-called silylenes, represent attractive organosilicon building blocks. Isolable stable silylenes remain scarce, and in most hitherto reported examples, the silicon center is stabilized by electron-donating substituents (e.g., heteroatoms such as nitrogen), which results in electronic perturbation. In order to avoid such electronic perturbation, we have been interested in the chemistry of reactive silylenes with carbon-based substituents such as ferrocenyl groups. Due to the presence of a divalent silicon center and the redox-active transition metal iron, ferrocenylsilylenes can be expected to exhibit interesting redox behavior. Herein, we report the design and synthesis of a bis(ferrocenyl)silirane as a precursor for a bis(ferrocenyl)silylene, which could potentially be used as a building block for redox-active organosilicon compounds. It was found that the isolated bis(ferrocenyl)siliranes could be a bottleable precursor for the bis(ferrocenyl)silylene under mild conditions.     

Coreduction methodology for immiscible alloys of CuRu solid-solution nanoparticles with high thermal stability and versatile exhaust purification ability

This study provides a coreduction methodology for solid solution formation in immiscible systems, with an example of a whole-region immiscible Cu–Ru system. Although the binary Cu–Ru alloy system is very unstable in the bulk state, the atomic-level well-mixed CuRu solid solution nanoparticles were found to have high thermal stability up to at least 773 K in a vacuum. The exhaust purification activity of the CuRu solid solution was comparable to that of face-centred cubic Ru nanoparticles. According to in situ infrared measurements, stronger NO adsorption and higher intrinsic reactivity of the Ru site on the CuRu surface than that of a pure Ru surface were found, affected by atomic-level Cu substitution. Furthermore, CuRu solid solution was a versatile catalyst for purification of all exhaust gases at a stoichiometric oxygen concentration.

This study provides a coreduction methodology for solid solution formation in immiscible systems, with an example of a whole-region immiscible Cu–Ru system.     

Fully Aromatic Block Copolymers for Fuel Cell Membranes with Densely Sulfonated Nanophase Domains

Two multiblock copoly(arylene ether sulfone)s with similar block lengths and ion exchange capacities (IECs) were prepared by a coupling reaction between a non‐sulfonated precursor block and a highly sulfonated precursor block containing either fully disulfonated diarylsulfone or fully tetrasulfonated tetraaryldisulfone segments. The latter two precursor blocks were sulfonated via lithiation‐sulfination reactions whereby the sulfonic acid groups were exclusively placed in ortho positions to the many sulfone bridges, giving these blocks IECs of 4.1 and 4.6 meq·g⁻¹, respectively. Copolymer membranes with IECs of 1.4 meq·g⁻¹ displayed well‐connected hydrophilic nanophase domains and had decomposition temperatures at, or above, 300 °C under air. The copolymer with the tetrasulfonated tetraaryldisulfone segments showed a proton conductivity of 0.13 S·cm⁻¹ at 80 °C under fully humidified conditions, and surpassed that of a perfluorosulfonic acid membrane (NRE212) by a factor of 5 at –20 °C over time.