Enzymatic chemoselective synthesis of secondary-amide surfactant from N-methylethanol amine

Efficient selective synthesis of the secondary amide surfactant N-methyl lauroylethanolamide from methyl laurate and N-methylethanol amine by carrier-fixed Chirazyme L-2 (Candida antarctica) using a kinetic strategy has been demonstrated. When different solvents were screened for product yields using Chirazyme L-2, acetonitrile was found to be optimal. The rate of the reaction increased sharply by increasing the molar ratio of the reactants and the reaction temperature. When the reaction was performed at 50 degrees C for 36 h with 50 mmol ester and 100 mmol amine, the product was obtained in a 97.1% yield. With 50 mmol ester and 150 mmol amine, the highest yield (97.3%) was obtained after 16 h of incubation at 50 degrees C. It took only 5 h to get a yield of 95.8% at 60 degrees C using 50 mmol ester and 200 mmol amine. The enzyme activity in the amidation reaction mixture did not decrease notably even after six uses.     

Picosecond signal sampling and multiplication by using integrated tandem light modulators

A picosecond signal sampling experiment was performed successfully by using integrated optic technologies. Two interferometric modulators of the traveling-wave and lumped types were integrated in series on a LiNbO3crystal surface. The traveling-wave modulator was oprated as a sampling gate activated by an electrical pulse train of 1-GHz repetition from a comb generator, while the lumped one was driven by a 2-GHz CW signal. The aperture time of the gate was estimated about 52 ps from the measurement using the image tube streak camera modified to sinusoidal scan at 1 GHz. Also a signal multiplication experiment was carried out using 100- and 10-MHz CW signals.     

Surface modification of polymethyl methacrylate by graft copolymers

Summary Graft copolymers composed of poly(methyl methacrylate) branches and different backbones of poly(fluoroalkyl acrylate(FA)-co-methyl methacrylate(MMA)), poly (hydroxyethyl methacrylate(HEMA)-co-MMA), and poly(FA-co-HEMA) were prepared by macromonomer technique to study their application as a surface modifier for PMMA films. Contact angle of water droplet on PMMA film specimens containing various amounts of these graft copolymers cast on glass slides from THF solution was found to change considerably with the graft copolymer concentration, depending on their backbone component. And there was considerable difference in contact angle between air and glass side of the film surfaces. These results were considered in terms of the surface accumulation of graft copolymers during the solvent evaporation.     

Synthesis and application of fluorine containing graftcopolymers

Summary Well-defined graftcopolymers were prepared by radical copolymerization of methyl methacrylate macromonomer with perfluoroalkyl acrylate. Contact angle of the solvent cast films of poly(methyl methacrylate) containing various amount of the graftcopolymer was measured against water droplet. Addition of 0.2 wt% of the graftcopolymer was sufficient to improve the polymer films to water repellent surfaces, while 10 wt% was necessary to modify the polymer surfaces to the same level of water repellency.     

Effect of chemical structure of monoamide resins on adsorptivity to uranium(VI) in nitric acid media

For the development of resins with selectivity for uranium(VI) in nitric acid media, some silica-supported monoamide resins with different chemical structures have been newly synthesized and the adsorptivities to U(VI) in HNO₃ have been examined based on our previous results that the chemical structure of monoamide resins might largely affect their adsorptivities to U(VI). The resin consisting of N-vinyl-2-pyrrolidone was found to show relatively strong adsorptivity to U(VI) in the wide concentration range of HNO₃ and little dependence on them. On the other hand, the adsorptivity to U(VI) of the resin with methylacetamide showed dependence on HNO₃ concentrations such as dimethylacrylamide (DMAA) resins which were previously studied, whereas the affinity to U(VI) was smaller than those of DMAA resins. According to the probable adsorption mechanism of U(VI) onto monoamide resins that two oxygen atoms of the two amide groups coordinate to U(VI), the adsorption data suggest that the adsorptivity of monoamide resins is strongly affected by the ‘chelating effect’, namely there are some optimum numbers of the atoms participating in the chelating formation.     

Tribochemical interactions between Zndtp,Modtc and calcium borate

Tribochemical interactions between antiwear zinc dithiophosphate (Zndtp), friction modifier molybdenum dithiocarbamate (Modtc) and overbased detergent calcium borate (OCB) lubricant additives have been investigated. Friction tests were performed in mild wear conditions under boundary lubrication, in order to enhance tribochemical surface effects. The nature of tribofilms formed was studied by coupling high‐resolution TEM on wear fragments and inside‐wear‐scar, micro‐spot XPS in the same location of the wear track (so‐called dual analysis). The performance of the Modtc/Zndtp mixture is mainly due to the generation of MoS₂ single sheets and the digestion of MoO₃ in the zinc polyphosphate glass formed. The final result of the tribochemical reaction is a two‐phase tribofilm composed of (i) non‐oriented MoS₂ sheets (friction modifier) embedded in a carbon‐rich phase and (ii) a mixed Zn/Mo polyphosphate glass (antiwear). The Modtc/OCB mixture has a similar antiwear mechanism except that the oxide is not completely eliminated, due to the softer action of borate anion compared with phosphate one. Compared to the data obtained with binary combinations (Modtc/Zndtp, Modtc/OCB and Zndtp/OCB), we show here that the ternary system Modtc/Zndtp/OCB provides both a low wear rate and an ultralow friction value, while adding detergent and anti‐corrosive properties to the formulation. Our analytical data indicate that the synergistic effect can be attributed to an outstanding nanostructure of the tribofilm formed. It is composed of a single‐phase material containing perfectly oriented MoS₂ single sheets embedded in a calcium and zinc borophosphate glass. The ternary system produces a smart material in the interface, because both functions (antiwear and friction reduction) are correlated. Compared to phosphate alone, the mechanism by which MoS₂ sheets have been oriented in the borophosphate could be related to aligned molecules of the glassy polymer in the direction of sliding. This revised version was published online in July 2006 with corrections to the Cover Date.     

A One-Dimensional Propagation of Shock Wave Supported by Atmospheric Millimeter-Wave Plasma

A shock wave supported by an atmospheric breakdown plasma caused by a high-power millimeter-wave beam was studied. The shadow graph image in a shock tube visualized the one-dimensional shock-wave generated by the millimeter-wave breakdown in atmosphere for the first time. It was revealed that a normal shock wave propagated through the tube at the constant velocity while it was detached from the ionization front of the plasma whenever the propagation velocity of the ionization front was supersonic or subsonic. And it was visually clarified that the atmospheric millimeter-wave breakdown had the combined structure of the normal shock wave and the heating region of the millimeter-wave plasma. The measured pressure of the shock front was as equal as the normal shock which propagated at measured Mach number.     

Muscle activity during gait-like motion provided by MRI compatible lower-extremity motion simulator

This paper describes an evaluation of muscle activity of volunteers while they undergo gait-like motion in their dorsal position supported by our lower-extremity motion simulator (LoMS) that is magnetic resonance imaging (MRI) compatible. Our LoMS is designed to provide gait-like motion for a wearer in his/her dorsal position while a functional MRI measures his/her brain activity. A purpose of providing gait-like motion by LoMS is to enable a wearer in the dorsal posture to move his/her lower extremities like gait. LoMS is controlled with torque control based on predictive control method to convert the gravity effect of the dorsal posture into the caudal posture. The performance providing gait-like motion is evaluated from two viewpoints of muscle activities: bioelectrical potential (BEP) transition and inhibition of musculus soleus during the motion. There were correlation of BEP transition at iliopsoas, quadriceps femoris, musculus tibialis anterior, and musculus soleus. The inhibition during the gait-like motion provided by LoMS was similar to the inhibition during treadmill gait. The inhibition is modulated by a level of cerebellum, brainstem and spinal. Therefore, it is considered that LoMS induces the motor sensation in the level of cerebellum, brainstem, and spinal by providing the gait-like motion.     

Saccharomyces cerevisiae protein phosphatase Ppz1 and protein kinases Sat4 and Hal5 are involved in the control of subcellular localization of Gln3 by likely regulating its phosphorylation state

A Saccharomyces cerevisiae mutant lacking PPZ1, encoding a serine/threonine protein phosphatase (PPase), is caffeine-sensitive. To clarify the function of Ppz1 in resistance to caffeine, we attempted systematically to identify protein kinase (PKase) whose disruption lead to suppression of caffeine sensitive phenotype of the ?ppz1 disruptant since disruption of PPZ1 might cause caffeine sensitivity by increasing its phosphorylated substrates and we presumed that disruption of genes for PKase sharing the substrate with Ppz1 could restore the resistance through bypassing necessity for dephosphorylation of substrates. Among the 102 viable pkase disruptions, disruption of either SAT4 or HAL5 suppressed the caffeine sensitivity phenotype and increased expression of ENA1, encoding a P-type ATPase of the ?ppz1 disruptant. Because increased expression of ENA1 in the ?ppz1 disruptant was found to be suppressed by disruption of GLN3, localization and phosphorylation of Gln3 in the ?ppz1 disruptant was compared to that in the ?ppz1?sat4 and ?ppz1?hal5 double disruptants. Gln3 was found to accumulate in the nucleus in the ?ppz1 disruptant, and this nuclear localization was abolished by disruption of either SAT4 or HAL5. Interestingly, the level of Gln3 phosphorylation in the ?ppz1?sat4 and ?ppz1?hal5 disruptants decreased relative to wild type independent of caffeine. From these observations, we conclude that Ppz1 controls Gln3 localization by regulating its phosphorylation state in combination with Sat4 and Hal5.     

Comparison of hydrogen isotope retention and irradiation damage behaviors in tungsten and SS-316 with simultaneous C+–D2+ implantation

Behaviors of hydrogen isotope retention and damages in tungsten and SS-316 with simultaneous C⁺–D₂⁺ implantation were compared to those with only D₂⁺ implantation using X-ray photoelectron spectroscopy (XPS), Thermal desorption spectroscopy (TDS), glow discharge-optical emission spectroscopy (GD-OES) and Transmission electron microscopy (TEM).The total D retention for SS-316 with only D₂⁺ implantation was about 45% as large as that for tungsten. The D retention for simultaneous C⁺–D₂⁺ implanted tungsten and SS-316 clearly increased as a factor of 1.7, which is almost the same among these samples. The density of dislocation loops was enhanced by the simultaneous C⁺–D₂⁺ implantation, indicating the D trapping site would be produced by C⁺ implantation. As for the D desorption temperature, small shift toward lower temperature side was found for SS-316 compared to tungsten, indicating the D trapping energy by dislocation loops and grain boundary for SS-316 is lower than that for tungsten.