Supramolecular Nanotube Reactors for Production of Imine Polymers with Controlled Conformation,Size, and Chirality

A series of supramolecular nanotubes with inner diameters of 1, 4, 9, 12, 16, and 29 nm are prepared from amino acid lipids. The hydrophobic channels of the nanotubes act as reactors for the formation of imine polymers by not only effectively encapsulating the benzaldehyde and diacetyleneamine precursors of the imine monomers but also markedly accelerating imine formation. The nanotube inner diameter determines whether the imine monomers self‐assemble into nanoparticles, nanotapes, nanocoils, or twisted nanofibers in the channels. UV‐induced polymerization of the diacetylene units in the imine nanostructures followed by decomposition of the nanotubes into molecular dispersions of the constituent amino acid lipids results in expulsion of the polymerized imine nanostructures with retained conformation. The isolated nanocoils and twisted nanofibers retain the helicity and circular dichroism induced by the nanotubes, which exhibits supramolecular chirality, even though the components of the imine monomers are achiral. These supramolecular nanotubes with tunable diameters and functionalizable surfaces can be expected to be useful for the production of polymers with controlled conformation, size, and chirality without the need for rational design or chemical modification of the monomers or optimization of the polymerization conditions.     

Nonlinear Response Analysis Considering Dynamic Stiffness with Both Frequency and Strain Dependencies

The time domain evaluation of the frequency-dependent dynamic stiffness was studied and some transform methods are being proposed. In this paper, the nonlinear response analysis method of the dynamic stiffness with both frequency and strain dependency was studied. First, the frequency-dependent complex stiffness was calculated at each strain level, and then they were transformed to the impulse response in the time domain. The characteristics of the complex stiffness and the impulse response of both two-layered soil and viscoelastic dampers were investigated. Then, the nonlinear time-history response analysis method considering both dependencies using the impulse response of each strain level was proposed. The earthquake response analysis of a structure on the two-layered soil was carried out as an example. The efficiency of the method was confirmed through these investigations.     

Designing Double Pore Structure in Alkoxy-Derived Silica Incorporated with Nonionic Surfactant

The principle of designing double-pore structure in alkoxy-derived silica is described with the experimental system containing polyoxyethylene nonylphenylether. The formation of macropores is consistently explained in terms of the concurrence of a phase separation and a sol-gel transition in the polymerizing silica-surfactant-solvent system. The composition-morphology relationship exhibited a substantial variation depending on the length of oxyethylene units in the surfactant molecule. The mesopore volume obtained after basic solvent exchange and a heat-treatment suggested that the surfactant with shorter oxyethylene chain tends to be incorporated more in the gel phase to give higher mesopore volume. The small-angle X-ray scattering measurement of the gelling and aging system supported this hypothesis indicating micelle formation in the system containing a surfactant with shorter oxyethylene chain.     

Factors of hetero space charge generation in XLPE under dc electric field of 20 kV/mm

This report deals with the mechanism of space charge accumulation in cross‐linked polyethylene (XLPE) under dc electric field. Space charge was measured by the pulsed‐electroacoustic method with applying dc stress of 20 kV/mm. A large amount of hetero space charge accumulated in fresh XLPE samples. Factors influencing the space charge accumulation were analyzed in regard to cross‐linking by‐products and antioxidant. No space charge was seen when the fresh sample was degassed to remove cross‐linking by‐products. Introducing acetophenone, one of the cross‐linking by‐products, in a degassed sample produces no space charge, suggesting that acetophenone itself could not be the direct factor of space charge formation. However, heating this sample up to 150 °C results in formation of hetero space charges as in virgin samples. Hence, it is concluded that hetero space charges may be formed when impurities, such as an antioxidant, dissociate thermally with the help of acetophenone and that the dissociated products are attracted toward both electrodes under a dc field to form the hetero space charges. © 1999 Scripta Technica, Electr Eng Jpn, 129(2): 13–21, 1999     

The dissociation process in plasma-enhanced chemical vapor deposition using tetraethoxysilane

Dissociation in plasma-enhanced chemical vapor deposition for SiO₂ deposition using tetraethoxysilane (TEOS) was investigated by means of mass spectrometry. First we obtained the basic dissociation patterns of TEOS by electron impact. It was shown that TEOS was dissociated by electron impact at low electron energies below 7 eV, removing the ethyl group (C₂H₅). Next we determined dissociation patterns in TEOS/He plasma in order to eliminate the effect of oxidation. Finally, dissociation in TEOS/O₂ plasma was investigated. It was found that oxidation plays an indispensable role in the deposition of high-quality SiO₂ films due to the decrease in high-molecular-weight compounds with carbon and hydrogen, although TEOS is highly dissociated by electron impact. © 1999 Scripta Technica, Electr Eng Jpn, 129(4): 32–38, 1999     

The excellent water-solubility of N-[3-(dimethyl-amino)propyl] docosanamide chloride : the most eco-friendly cationic hair conditioning agent

A new hair-conditioning agent, N-[3-(dimethylamino)propyl]docosanamide (APA-22) hydrochloric acid salt (APA-22 HCl), has excellent solubility in water with a solubility limit over 10-times larger than that of other APA hydrochloric salts with shorter alkyl chain lengths. The physicochemical characteristics of APA-22 HCl were studied at 25 degrees C by using equilibrium surface tension (gamma), solubilization of an oil-soluble dye, steady-state fluorescence, and chloride ion selective electrode techniques. The APA-22 HCl salt is considered to form an aggregate at a concentration, C(1), which is about twice the concentration of the solubility limit of APAs with shorter alkyl chains. At a higher concentration, C(2), the aggregates of APA-22 HCl start forming another kind of aggregate, which is able to solubilize oil-soluble materials. That is, C(1) is considered to represent the critical aggregation concentration (cac) and C(2) a morphology transition. In the concentration region between C(1) and C(2) the solutions are seemingly transparent whereas at above C(2) they appear bluish or translucent. Since the Krafft point of APA-22 HCl is 55 degrees C, all the solutions, including the aggregates, are thought to exist in metastable states. Notably, however, these metastable solutions do not change significantly over a few months. The excellent solubility of APA-22 HCl in water is considered to be a result of this unique stepwise aggregation with increasing concentration.     

Metabolism of odd-numbered fatty acids and even-numbered fatty acids in mouse

Fatty acids are converted into energy via beta-oxidation. Although almost all natural occurring fatty acids are even-numbered, there are some odd-numbered fatty acids too. The details of the metabolism rate of odd-numbered fatty acids, however, are not clear. In the present study, we simultaneously administered a triacylglycerol containing four types of labeled even-numbered (palmitic acid and stearic acid) and odd-numbered (pentadecanoic acid and heptadecanoic acid) fatty acids to mice to compare the rates of their metabolism. The rates of metabolism were evaluated based on the accumulation of the labeled fatty acids in the small intestine epithelium, liver, and epididymal fat. Odd-numbered fatty acids accumulated mainly in the epididymal fat. In contrast, there was no accumulation of even-numbered fatty acids observed in the small intestine epithelium, liver, or epididymal fat. These results suggest that odd-numbered fatty acids might not be favorable substrates for beta-oxidation-related enzymes.     

Nickel/Zinc Chloride‐Promoted Domino Reaction of Enynes and Enones Including Unstrained C?C Bond Cleavage

Unstrained C C bond cleavage proceeds during the domino reaction of enynes and enones that includes successive C C bond formation under the nickel/zinc/zinc chloride system. The cleavage occurs through β‐syn‐elimination of the 1,3‐dicarbonyl part. In addition, β‐carbon elimination is selective, unlike the β‐hydrogen elimination in the presence of excess zinc chloride.     

Superior performance of non-activated multi-walled carbon nanotube polymer actuator containing ruthenium oxide over a single-walled carbon nanotube

The electrochemical and electromechanical properties of actuators developed using a non-activated multi-walled carbon nanotube (MWCNT)–ionic liquid (IL) gel electrode containing ruthenium oxide (RuO₂) were compared with only-MWCNT and only-single-walled carbon nanotube (SWCNT) based actuators. The double-layer capacitance of the non-activated MWCNT electrode containing RuO₂ was larger than that of the only-MWCNT electrode. The non-activated MWCNT polymer actuator containing RuO₂ surpassed the performance of the only-MWCNT and only-SWCNT actuators in terms of the strain and maximum generated stress. Both MWCNTs and RuO₂ were required to produce large strain and quick response actuators that surpassed the performance of the only-SWCNT polymer actuator and exhibited characteristics sufficient for practical applications (e.g. tactile display).