Development of a nuclear magnetic resonance system for in situ analysis of hydrogen storage materials under high pressures and temperatures

A NMR system for in situ analysis of hydrogen storage materials under high pressure and temperature conditions was developed. The system consists of a gas pressure and flow rate controlling unit, a temperature controller, a high temperature NMR probe tunable for both (1)H and other nuclei, and a sample tube holder. Sample temperature can be controlled up to 623 K by heated N(2) gas flow. Sample tube atmosphere can be substituted by either H(2) or Ar and can be pressurized up to 1 MPa under constant flow rate up to 100 ml/min. During the NMR measurement, the pressure can be adjusted easily by just handle a back pressure valve. On the blank NMR measurement, (1)H background noise was confirmed to be very low. (1)H and (11)B NMR spectrum of LiBH(4) were successfully observed at high temperature for the demonstration of the system. The intensity of the (1)H NMR spectra of H(2) gas was also confirmed to be proportional to the applied pressure.     

A Note on the Time Constant in Low-Pass Filtering of Rectified Surface EMG

A procedure to obtain the optimal time constant in low-pass filtering of surface EMG has been developed. The performance index which determines the optimality of the time constant considers the sensitivity of the filter and the reproducibility of the filtered output. In our procedure, the optimal time constant can be easily calculated from a nonlinear equation which is characterized by the autocorrelation coefficient of the given muscular performance and the mean and variance of surface EMG in static contraction.     

A novel alkaline air electrode based on a combined use of cobalt hexadecafluoro-phthalocyanine and manganese oxide

Electrocatalytic reduction of O₂ with dual catalysts of cobalt 1, 2, 3, 4, 8, 9, 10, 11, 15, 16, 17, 18, 22, 23, 24, 25-hexadecafluoro-29 H, 31H-phthalocyanine (CoPcF₁₆) and MnOOH was studied in alkaline media with cyclic and rotating ring-disk electrode (RRDE) voltammetry. Cyclic voltammetric results show that CoPcF₁₆ possesses a good catalytic activity for redox-catalyzing an apparent two-electron reduction of O₂ with superoxide (O₂⁻) as an intermediate. The combined use of CoPcF₁₆ with MnOOH which shows a bifunctional catalytic activity toward the sequential disproportionations of the reduction intermediate and product, i.e. O₂⁻ and peroxide (HO₂⁻), eventually enables an apparent four-electron reduction of O₂ to be achieved at a positively-shifted potential in alkaline media. The possibility of utilizing the dual catalysts for the development of practical alkaline air electrodes was further explored by confining the catalysts in active carbon (AC) and carbon black (CB) matrices that are generally used as the substrate for constructing air electrodes. The RRDE voltammetric results suggest that an apparent four-electron reduction of O₂ reduction can be obtained at the as-prepared carbon-based air electrode at a potential close to that at the Pt-based air electrode, and that the as-prepared electrode shows a high tolerance against methanol and glucose crossover.     

Fabrication of diffraction grating for X-ray Talbot interferometer

Imaging technology using the phase data attracts attention from many researchers as the observation technique of a biomechanical material. We produced a diffraction grating for obtaining high-resolution phase data. We designed the new process flow and developed the fabrication technique composed of MEMS technology, X-ray lithography, and micro electroplating. The X-ray lithography process was performed using the NewSUBARU synchrotron radiation facility. The line and the aspect ratio of this grating were 4 μm and above 5 μm, respectively. We evaluated the diffraction grating in SPring-8.     

Large area and wide dimensions X-ray lithography using energy variable synchrotron radiation

We developed a new X-ray lithography system for the lithographite, galvanoformung and abformung (LIGA) process using synchrotron radiation at the New SUBARU facility of the University of Hyogo. The X-ray lithography system can utilize two different energy regions: one is a high-energy region: from 2 to 12 keV, and the other is a low-energy region from 1 to 2 keV. Each energy region can be selected in accordance with the size and shape of the desired microstructures. Large-area patterning across an A4-size area was successfully performed with a highly uniform pattern thickness. Furthermore, high-aspect-ratio patterning using a high-X-ray-energy region was also achieved using this X-ray lithography system.     

Design of solenoidal electromagnetic microactuator utilizing 3D X-ray lithography and metalization

Investigations of microactuators are actively being pursued in various viewpoint, researchers are exploring output energy sources such as electrostatic, piezoelectric, electromagnetic and etc. We focus attention recently on the electromagnetic microactuator. In generally, electromagnetic actuator is not well suited to miniaturization because of decreased output force when miniaturized. However, we have already developed 3D-LIGA process to produce a spiral microcoil in 2003. Then, the production process of a smaller and higher output force microactuator was devised based on this technology.     

Inclusion of bisphenols by a self-assembled monolayer of thiolated calix[6]arene on a gold surface

The molecular recognition of various kinds of bisphenols (BPs) by a self-assembled monolayer (SAM) of thiolated calix[6]arene on a gold electrode was examined using cyclic voltammetry (CV). Based on the inhibitory effect of BPs on the inclusion of hydroquinone (HQ) as a probe bythe surface-confined calix[6]arene, the association constants (Kassoc) of BPs with the immobilized calix[6]arene were estimated. The Kassoc values for BPs with the SAM of thiolated hexasodium calix[6]arenehexasulfonic acid (thioSCX6) were much smaller than those in the free calix[6]arene derivative systems reported previously. The order of the Kassoc values for BPs with thioSCX6 was bisphenol A (BPA) > bisphenol S (BPS) > bisphenol B (BPB) > bisphenol F (BPF). The Kassoc values for BPA and BPS with thioSCX6 were larger than that for BPB, despite the larger hydrophobicity of BPB than that of BPA and BPS. This is probably because the inclusion phenomena in this system are not simply driven by the hydrophobic interaction, but are significantly affected by several steric and structural factors with immobilization of the host. Those are (1) a decrease in flexibility of the SCX6 cavity by the formation of SAM, (2) a decrease in inclusion ability of the SCX6 by the presence of Au surface just beneath it, and (3) a repulsion of hydrophobic guests bythe presence of sulfonate groups at the top of the SAM. Moreover, the association phenomena (adsorption and desorption processes) of a bisphenol with the SCX6 SAM were examined directly by using localized surface plasmon resonance spectroscopy.     

Micro-tribological properties of heat treated hard disk evaluated by force modulation method

As evaluation of the durability of lubricant and heat cure treated perpendicular hard disks was carried out. With regard to the heat treated perpendicular hard disks, their micro-tribological properties such as hardness, storage modulus, loss modulus, and tan δ have been evaluated by scanning probe microscopy (SPM). In the quasistatic nanoindentation hardness test, it can be observed that nanoindentation hardness in the valleys is higher than that on the hill, and the hardness of the hard disk was increased after it was heat treated. Corresponding to the results of quasistatic nanoindentation in a dynamic nanoindentation test, storage modulus and loss modulus were increased after the heat treatment. Moreover, tan δ also has increased as viewing of viscoelastic properties. On the other hand, for microwear properties, the wear depth of the heat-treated disk and its wear volume were decreased by heat treatment, corresponding to the result of quasistatic nanoindentation.     

Continuous synthesis of glycerides by lipase in a microporous membrane bioreactor

A membrane bioreactor was developed for continuous synthesis of glycerides by lipase to overcome the drawbacks associated with the usual operation in an emulsion system. One unit (total area: 726 cm²) of flat, plate-type dialyzer was used as the membrane bioreactor at 40 C. The glycerol solution, containing bacterial lipase and water, was supplied continuously to 1 side of a sheet of microporous polypropylene membrane (strongly hydrophobic) and the effluent was recycled, while undiluted liquid fatty acid (oleic or linoleic) was fed continuously to the opposite side of the membrane and came in contact with a glycerol-water-lipase solution to cause the reaction. The product, glycerides, was obtained at the outlet, in a pure state, with no other phase. Highest conversion (ca. 90%) was obtained when the water content of the glycerol solution was 3–4%. As the accumulation of water produced by the reaction lowered the conversion, molecular sieves in a column that the glycerol solution passed through were used for optimal water content. The reaction could be continued at least for 1 month, yielding a conversion above 70% when 1% CaCl₂ was added in the glycerol solution. The main component of glycerides formed was almost equimolar amounts of mono-and diglycerides.     

Regeneration of carbon containing sodium dodecylbenzene sulfonate—cyclic regeneration with steam in fluidized beds

Cyclic regeneration of activated carbon containing adsorbed sodium dodecyl-benzene sulfonate (DBS) was studied in fluidized beds at 1119 K and 101.3 kPa. Optimum restoration of adsorption capacity (97.2% per cycle) resulted when gasification with 21.5% steam was continued for 200 s. At that time, about 85% of the DBS added to the carbon during the adsorption process had been removed. Because of the adsorbed inorganic residue from DBS, these results are somewhat different from earlier studies with the sucrose-carbon system. With sucrose, maximum restoration of adsorption capacity was achieved when a weight equivalent to 100% of the adsorbed sucrose was removed by thermal decomposition and steam gasification.