Intermolecular Interaction of [60]Fullerene with Tröger's Base Analogues

Tröger's base (TB, 1) and its analogues were synthesized and were subject to the titration experiments to evaluate their ability of supramolecular complexation with C₆₀. Results demonstrate clearly that the fluorene-based TB analogue (2) and the bioctylfluorene-based TB analogue (3) show 1:1 binding with C₆₀ to form the corresponding complexes while TB 1 does not. Titration experiments exhibited that the association constant (K_ass) of 3/C₆₀ (48.1 ± 7.9 M ^?1) was larger than that of 2/C₆₀ (13.7 ± 1.4 M ^?1)_. The formation of the 1:1 binding complexes 2/C₆₀ and 3/C₆₀ was also confirmed by MALDI-TOF mass spectrometry. Theoretical calculations suggest that 2 and 3 have appropriate cavities to embrace C₆₀. These findings indicate that not only the π/π interaction between the fluorene moieties and the C₆₀ surface but also the CH/π interaction between the octyl groups and the C₆₀ surface serve efficiently in the supramolecular complexation with C₆₀.     

Baseband Feedback Frequency-Division Multiplexing with Low-Power dc-SQUIDs and Digital Electronics for TES X-Ray Microcalorimeters

We are developing frequency-division multiplexing (FDM) systems with baseband feedback for TES X-ray microcalorimeter arrays for use with the DIOS mission. To meet the requirement of limited cooling capacity at cryogenic temperatures, we developed low-power and FDM-optmized dc-SQUIDs. To make maximum use of the SQUIDs, we also developed digital electronics using FPGA evaluation boards and ADC/DAC FMC daughter cards, and evaluated signal-to-noise ratios and gain-bandwidth products.     

Radiation Tolerance Evaluation of the Ti/Au Bilayer TES Microcalorimeter

We have developed Ti/Au bilayer transition-edge sensor (TES) microcalorimeters for future X-ray astrophysical satellite missions such as DIOS. One possible concern on the space use of TES microcalorimeters is its radiation tolerance. We have evaluated the performance of a Ti/Au bilayer (30/40 nm thick) TES microcalorimeter with 1.5  \(\upmu \) m thick Au absorber, before and after irradiation of 150 MeV proton beam with a total dose of 10 krad, corresponding to 10 years in the low Earth orbit. No significant changes on transition temperature, sensitivity, normal resistance, and critical current were observed. The energy resolution for 5.9 keV X-rays was 5.6  \(\pm \)  0.3 eV (FWHM) after the irradiation, which was slightly worse than 5.1  \(\pm \)  0.3 eV before the irradiation. We consider that our TES has sufficient radiation tolerance in orbit.     

First-Order Phase Transition and Anomalous Hysteresis of Binary Bose Mixtures in an Optical Lattice

We study a first-order phase transition between superfluid and Mott insulator phases in binary Bose mixtures loaded into a hypercubic optical lattice. The system is described by a two-component Bose-Hubbard model. Considering the difference between the two kinds of bosons in the intra-component interaction strength, we discuss the metastability of the system and the hysteresis associated with the first-order superfluid-Mott insulator transition. It is found that the sweeping of hopping amplitude induces a conventional hysteresis-loop behavior. We also find an anomalous hysteresis behavior when the chemical potential is varied. In the anomalous hysteresis, the phase transition occurs in a unidirectional way and a hysteresis loop does not form.     

Excess micromotion compensation of trapped ions in a linear Paul trap for trace isotope analysis

Excess micromotion of trapped calcium ions was detected and compensated in our linear Paul trap apparatus for trace isotope analysis. The micromotion was detected by Charge-coupled device (CCD). camera and radio frequency (rf) correlation method. We found that 230 and 2280 V of compensation voltages were needed for x- and y-axis compensation in our apparatus, respectively. The z-axis micromotion was confirmed by the experiment and its cause was investigated by finding a shape of z-axis confinement field. The confinement field was indeed distorted in our apparatus and it gave rise to the trapped ion to shift from potential center. And the micromotion of r-direction was transferred to the z-axis by the distorted confinement field. The z-axis micromotion was suppressed by increasing cap voltage of trap.     

Operation Assist by Vibration Suppression Control Using Impulse‐Shaped Signals for Power Assist Conveyance System

This paper presents an assist control method for a flexible parts conveyance task using a power assist conveyance system. The assist control method should be designed so as not only to suppress vibration but also to reduce the degradation of operating feel. For this purpose, multiple impulse‐shaped signals are used as feedforward signals in order to reduce the vibration of flexible parts during conveyance. In addition, the adjustment time is introduced to adjust the input timing of the impulse‐shaped signal and to suppress vibration. In order to improve the degradation of operating feel, the smaller amplitudes of the three impulse‐shaped signals are used and input repeatedly. The effectiveness of the proposed system was verified experimentally. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(2): 31–39, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22476     

Synthesis and optical properties of azobenzene side chain polymers derived from the bifunctional fumaric acid and itaconic acid

Three type polymers containing the same azobenzene side chain group with different backbone structures, poly(DMAz6Fm), poly(DMAz6It) and poly(MAz6Ac) derived respectively from fumaric acid, itaconic acid and acrylic acid, were synthesized. The dependence of photo-response properties on the polymeric architecture was investigated for the solutions and films. By irradiation of the linearly polarized light (436 nm), uniaxial orientations of the thin films were induced and anisotropic properties were investigated by measurements of the order parameters and birefringence values.     

Effect of α-substituents on molecular motion and wetting behaviors of poly(fluoroalkyl acrylate) thin films with short fluoroalkyl side chains

The effect of α-substituent on the molecular motion and wetting behavior of poly{2-(perfluorobutyl)ethyl acrylate} [PFA-C₄], poly{2-(perfluorobutyl)ethyl methacrylate} [PFMA-C₄], poly{2-(perfluorobutyl)ethyl α-fluoroacrylate} [PFFA-C₄], and poly{2-(perfluorobutyl)ethyl α-chloroacrylate} [PFClA-C₄] films were characterized by dynamic contact angle measurement, lateral force microscopy (LFM), wide angle X-ray diffraction (WAXD), and X-ray photoelectron spectroscopy (XPS). WAXD of oriented PFClA-C₄ fiber suggested the presence of rod-like chain due to the presence of bulky α-substituent. The glass transition temperature (T_g) of PFFA-C₄ and PFClA-C₄ were well above the room temperature. The water repellencies of PFFA-C₄ and PFClA-C₄ were as high as that of PFMA-C₄ and their oil repellency of PFFA-C₄ and PFClA-C₄ was higher than the PFMA-C_4. This result was originated from the low main chain mobility of PFFA-C₄ and PFClA-C₄ due to the presence of bulky α-substituents. The effect of molecular motion on water repellency was clarified by the results of temperature dependence studies of dynamic contact angle, LFM, and surface chemical composition measured by XPS.     

Preparation of ultrafine polyurethane fiber web by laser‐electrospinning combined with air blowing

Thermoplastic polyurethane fiber webs were prepared using a laser‐heated electrospinning process combined with air blowing. The effect of spinning conditions such as air flow rate and air temperature on fiber diameter and molecular weight was investigated. Although the average fiber diameter decreased with increased air flow rate at each air temperature, the diameter increased when the air flow rate was >15 NL min^?1. In addition, the fiber was comparatively thicker with an increase in the air temperature. The variation in the fiber diameter tends to increase with the air flow rate, and a reduction in the molecular weight of the fiber by thermal degradation was suppressed. The thinnest and most uniform fiber with a diameter of 0.9 µm and a diameter coefficient variation of 15% was obtained at an air temperature of 25°C under an air flow rate of 15 NL min^?1. This fiber also had a minimum of decreased molecular weight. POLYM. ENG. SCI., 54:2605–2609, 2014. © 2013 Society of Plastics Engineers