Peptidyl human heart chymase inhibitors. 1. Synthesis and inhibitory activity of difluoromethylene ketone derivatives bearing P'' binding subsites

Appropriate structural modification of the difluoromethylene ketone derivatives at both P3 and P' positions led us to the discovery of peptidyl human heart chymase inhibitor 12h which shows potent activity with Ki = 6 nM and high selectivity against closely related serine protease bovine alpha-chymotrypsin (chymotrypsin Ki = > 100 microM). Using the compound 12b, a docking study with human heart chymase was carried out to presume probable interactions.     

Vortex Phase Diagram of Crossing-Lattices State in Bi2Sr2CaCu2O8+y

Phase diagram of a novel vortex state realized under tilted fields, crossing-lattices state, is extensively studied using Hall probe magnetometry. Precise measurements of angular dependence of second magnetization peak and the vortex penetration fields clarify the transition from the tilted lattice state to the crossing-lattices state. Under large tilted magnetic fields, irreversible magnetization and AC local permeability show several anomalies. With all these observations we construct a phase diagram identifying three boundaries with nearly constant c-axis fields and one with nearly constant in-plane field.     

Cross-Whisker Intrinsic Josephson Junction as a Probe of Symmetry of the Superconducting Order Parameter

As a test of the superconducting order parameter, we have developed an intrinsic Josephson junction by the name of cross-whisker junction. This junction was made using two Bi₂Sr₂CaCu₂O_8+d single crystal whiskers. Two whiskers were connected at their c planes with various cross-angles. Angular dependence of the critical current densities shows d-wave-like fourfold-symmetry. However, the angular dependence is much stronger than that of the conventional d_x ^{2-y 2} wave. The Jc shows its smallest value around 45 deg, which suggests that the Josephson penetration depth becomes longer. We have successfully observed a Fraunhofer pattern in the cross-whisker junction with cross-angle 45 deg.     

Acetic acid-doped poly(ethylene oxide)-modified poly(methacrylate): a new proton conducting polymeric gel electrolyte

A proton conducting polymeric gel membrane was first developed from poly(ethylene oxide)-modified poly(methacrylate) (PEO-PMA) containing poly(ethylene glycol) dimethylether (PEGDE). Acetic acid (HAc) was doped by immersing the polymeric film directly in the aqueous solution of HAc. Characterization by FT-IR, XRD and AC conductivity measurements were carried out on the film electrolytes consisting of different gel compositions. The ionic conductivity of the membrane showed a sensitive variation with the immersion time and concentration of the acid in the doping solution through the changes in the contents of acid and water in the gel. The ionic conductivity also depended on the PEGDE content in the polymer. The proton conductivity was 6.2×10⁻⁴ S cm⁻¹ at 20 °C and 1.0×10⁻³ S cm⁻¹ at 80 °C for the gel prepared from HAc concentration of 3.0 mol l⁻¹. The temperature dependence of the conductivity was found to be consistent with Arrhenius-type relationship at a temperature range from 20 to 80 °C, except for the films with low PEGDE contents. The apparent activation energy for the proton conduction was in the range of 5-30 kJ mol⁻¹, depending on the HAc concentration and the polymer matrix composition. The FT-IR spectra of the polymeric membranes showed that HAc does not protonate the carbonyl or ester groups of the polymer matrix, but interacts with them by the hydrogen bonding interaction or weak molecular interactions.     

Taste enhancer from the long-term ripening of miso (soybean paste)

Long-term ripened miso has a characteristic mouthfulness and continuity of flavour, which is heightened from 11 months of ripening. Focussing on its main components, changes of protein and sugar were investigated from 10 days up to 20 months of ripening. Protein and sugar changes during ripening did not correlate with sensory evaluation results. From visual observation of miso colour and colorimetric analysis of the water-soluble fraction, it was apparent that the Maillard reaction was occurring during 5–11 months of ripening. By fractionation and evaluation of umami, mouthfulness and continuity, we were able to identify a water soluble fraction of 20 month ripened miso with a molecular weight of 1000–5000 which was coloured and appeared to be a peptide that has undergone the Maillard reaction. From these results, the Maillard-reacted peptide was considered to be a key substance which gives the characteristic flavour (mouthfulness and continuity) of long-ripened miso.     

Effect of Water Adsorption on Microtribological Properties of Hydrogenated Diamond-Like Carbon Films

Microtribological properties of diamond-like carbon (DLC) films in the presence of water molecule have been studied. The amount of water adsorbed on DLC films was measured by the quartz crystal microbalance (QCM), while microtribological properties of the film were evaluated by an environment-controlled microtribometer. The hydrogenated-DLC showed an advancing water contact angle of 97°, indicating a relatively hydrophobic surface. No hysteresis in adsorption and desorption isotherms were observed. This suggests an absence of micropores at the DLC surface. The greatest adhesion and friction forces between a W-tip and DLC films deposited onto QCM were observed at a water coverage of 2-3 monolayers, which corresponds to a relative humidity of 70-80%. This abrupt increase in adhesion was explained by the generation of a meniscus from the condensed water between tip and DLC surface. The atomically flat DLC surface showed maximum adhesion and friction forces at lower humidity than those of DLC on OCM, implying the importance of surface texturing, which reduces the effect of water condensation.     

Study of sulfonation mechanism of low‐density polyethylene films with fuming sulfuric acid

Sulfonation of low‐density polyethylene (LDPE) films with fuming sulfuric acid was studied by X‐ray photoelectron spectroscopy (XPS) and attenuated total reflectance (ATR) infrared spectroscopy. The ATR spectra showed the formation of C?C double bonds and multiple sulfur atom containing groups for the sulfonation of LDPE films. This led us to propose that the abstraction reaction of hydride ion by sulfur trioxide (SO₃) in fuming sulfuric acid might account for the formation of the C?C double bonds. It was considered that after the abstraction reaction, these double bonds react with SO₃, resulting in the production of alkene sulfonic acids and sultones, along with the formation of sulfate groups as a result of reaction of the double bonds with sulfuric acid. Experimental data by treatment of the sulfonated LDPE films with KOH and thiourea supported the proposed idea, estimating the approximate molar ratio of the products. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2435–2442, 2004     

Precision nano-fabrication and evaluation of a large area sinusoidal grid surface for a surface encoder

This paper describes the fabrication of a large area sinusoidal grid surface, which is used as the measurement reference of a surface encoder for multi-axis position measurement. The profile of the grid surface is a superposition of sinusoidal waves in the X-direction and the Y-direction with spatial wavelengths of 100 μm and amplitudes of 100 nm. Diamond turning with a fast tool servo (FTS) was chosen as the fabrication method. The constructed FTS, which employs a piezoelectric tube actuator (PZT) to actuate the diamond tool and a capacitance probe as the feedback sensor, was confirmed to have a bandwidth of approximately 2.5 kHz and a tool displacement accuracy of several nanometers in the closed-loop mode. Experiments of fabricating the sinusoidal grid surface were performed on a commercially available precision diamond turning machine. An aluminum alloy workpiece was vacuum chucked on the spindle and the FTS was mounted on the X-slide. Efforts were made to position the tool tip to the center of the spindle (center-alignment) since it was verified that the center-alignment is important for the fabrication accuracy of the sinusoidal grid surface. An evaluation technique based on the two-dimensional (2D) discrete Fourier transform (DFT) of interference microscope images was also developed to evaluate the fabricated grid surface effectively. The fabrication result of a grid surface over an area of 150 mm has indicated the effectiveness of the fabrication system.     

Characteristics of self-excited combustion oscillation and combustion control by forced pulsating mixture supply

Characteristics of self-excited combustion oscillation are experimentally studied using confined premixed flames stabilized by a rearward-facing step. A new idea to suppress combustion oscillation was applied to the flames. The characteristics of unsteady combustion were examined, which is driven by forced pulsating mixture supply that can modulate its amplitude and frequency. The self-excited combustion oscillation having weaker flow velocity fluctuation intensity than that of the forced pulsating supply can be suppressed by the method. The effects of the forced pulsation amplitude and frequency on controlling self-excited combustion oscillations were also investigated comparing with the steady mixture supply. The unsteady combustion used in this experiment plays an important role in controlling self-excited combustion oscillations, and it also exhibits desirable performances, from a practical point of view, such as high combustion load and reduced pollutant emissions of nitric oxide.