Synthesis of colloidal polyoxazoline/silica hybrids prepared in an aqueous solution

New colloidal polymer hybrids with polyoxazolines such as poly(2-methyl-2-oxazoline) (PMeOZO) and poly(2-ethyl-2-oxazoline) (PEtOZO) were obtained in an aqueous solution as a sol-gel solvent. The polyoxazoline segment was incorporated into the siliceous particle and formed strong hydrogen bonds with silanol moieties, judging from TGA and FT-IR studies. Colloidal polymer hybrids exhibited no glass transition temperature of the polyoxazoline and showed excellent thermal stability and solvent-resistant property. Porous silica obtained by charring the colloidal polymer hybrids at 600 °C exhibited the peak at 3.5 Å. These results strongly indicate the homogeneous molecular scale dispersion of polyoxazoline in the colloidal silica gel matrix.     

Helmholtz resonance technique for measuring liquid volumes under micro-gravity conditions

The Helmholtz resonance technique has been investigated for measuring liquid volumes under micro-gravity conditions. We proposed a theoretical model of the Helmholtz resonance phenomenon induced in a closed container, and carried out a micro-gravity experiment to confirm the applicability of the measurement technique using water as a test liquid. A swept frequency signal was added to a loudspeaker, and together, a microphone and the loudspeaker picked up the sound of the Helmholtz resonance. The liquid volume was calculated from the Helmholtz resonance frequency using an equation derived from the theoretical model. The liquid volume obtained from the micro-gravity experiment agreed well with the liquid volume obtained under terrestrial conditions. Thus, it was confirmed that the Helmholtz resonance technique was applicable for measuring liquid volume under micro-gravity conditions.     

Analysis of electrocatalyst degradation in PEMFC caused by cell reversal during fuel starvation

The damage caused by cell reversal during proton exchange membrane fuel cell (PEMFC) operation with fuel starvation was investigated by a single cell experiment. The samples from degraded membrane–electrode assemblies (MEAs) were characterized. Chemical analysis of the anode catalyst layer of MEA samples by energy dispersive X-ray analysis (EDX) clearly showed ruthenium dissolution from the anode catalyst particles. Severe ruthenium loss was observed especially in the fuel outlet region. A reduced carbon monoxide (CO) tolerance was found by CO stripping voltammetry and measurement of deteriorated the fuel cell performance. Surface area loss of the cathode platinum by sintering was also detected by transmission electron microscopy (TEM) analysis and cyclic voltammetry.     

Simultaneous measurement of lens accommodation and convergence in natural and artificial 3D vision

Recent advances in 3D technology have been accompanied by increasing complaints of visual fatigue. The usual explanation for such fatigue is that accommodation and convergence are mismatched during stereoscopic vision. The aim of this study was to measure fixation distances between lens accommodation and convergence in young subjects while they viewed real objects and 3D video clips. Measurements were made using an original instrument. The 3D video clips were presented to subjects using a liquid crystal shutter glass system. The results showed that when viewing real objects, the diopter values of subjects' accommodation and convergence were similar and changed periodically. This measurement method was thus considered to be appropriate for the measurement of stereoscopic vision. We also investigated lens accommodation and convergence when subjects viewed 3D video clips. Both accommodation and convergence were found to move along with the virtual position of 3D video clips. Therefore, there was little discrepancy between accommodation and convergence during the viewing of 3D images.     

Investigation of two‐phase flow mixing between two subchannels

The cross flow between subchannels in a BWR fuel assembly has been typically analyzed using three types of mixing models, namely, pressure difference, turbulent mixing, and void drift which are expressed by time‐averaged flow parameters. However, in our previous paper, we expressed the above cross flow phenomenon simply by a fluctuating pressure model and confirmed its validity experimentally. In this present study, we examine the relationship between the fluctuating pressure difference and the cross flow rate more precisely by using a short mixing zone with no steady pressure difference. Results show that the experimental cross flow data agree well with the calculations using this model. Furthermore, we tried to express the fluctuating pressure difference by using a sinusoidal wave as a new cross flow model. This model is shown to have no dependence on frequency. We verify that the cross flow can be analyzed using only the pressure difference amplitude. © 2000 Scripta Technica, Heat Trans Asian Res, 29(5): 412–426, 2000     

Effect of crystallinity on electrochemical insertion/extraction of Li in transition metal oxides - Part II: TiO2, V2O5 and MoO3

Electrochemical insertion/extraction sf Li on cathode materials of anatase type TiO2, quasi-layered structure V2O5 and layered structure MoO3 was measured on samples of which structures were well characterized and showed a wide range of crystallinity. On the basis of experimental results on structure, morphology and charge-discharge characteristics, the effect of crystallinity of the cathode materials on electrochemical Li insertion/extraction performance was discussed. These three transition metal oxides were classified as one group on the basis of whether the crystallinity of these oxides affects to the performance or not, LiMn2O4 and LiCo0.5Ni0.5O2 belongs to the former group and TiO2, V2O5 and MoO3 to the latter.     

Basic study of high‐frequency carrier‐type magnetic field sensor using shape anisotropy

We tried to control the magnetic anisotropy of a high‐frequency carrier‐type magnetic field sensor by the shape of the magnetic film instead of induced anisotropy. We confirmed that the impedance of the sensor could be changed by applying a magnetic field. In addition, we tried to control the magnetic anisotropy with magnetostatic energy. We show that the properties of the sensor can be controlled by designing the shape of the magnetic film. © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Formation of IPN organic-inorganic polymer hybrids utilizing the photodimerization of thymine

Summary Formation of an interpenetrating polymer network (IPN) composed of organic polymer gel and silica gel in the form of polymer hybrids was conducted by utilizing the photodimerization of thymine bases. Thymine-modified poly(2-methyl-2-oxazoline) (POZO-T) was synthesized by the condensation reaction of partially hydrolyzed polyoxazoline and 1-(2-carboxyethyl)thymine. Organic-inorganic polymer hybrids were prepared from POZO-T and tetramethoxysilane (TMOS). Transparent and homogeneous polymer hybrids could be obtained. The photodimerization and the reverse reaction of thymine in the polymer hybrids were monitored by the UV absorption spectroscopy. Received: 27 March 2000/Revised version: 5 June 2000/Accepted: 15 June 2000