A multi-walled carbon nanotube/polymer actuator that surpasses the performance of a single-walled carbon nanotube/polymer actuator

Actuators were developed using activated and non-activated multi-walled carbon nanotube (MWCNT)–ionic liquid (IL) gel electrodes and compared to a single-walled carbon nanotube (SWCNT)-based actuator with respect to the electrochemical and electromechanical properties. The activated MWCNT–COOH/polymer actuator surpassed the SWCNT/polymer actuator in terms of the generated strain.     

Isotopomer analysis of production and consumption mechanisms of N2O and CH4 in an advanced wastewater treatment system

Wastewater treatment processes are believed to be anthropogenic sources of nitrous oxide (N(2)O) and methane (CH(4)). However, few studies have examined the mechanisms and controlling factors in production of these greenhouse gases in complex bacterial systems. To elucidate production and consumption mechanisms of N(2)O and CH(4) in microbial consortia during wastewater treatment and to characterize human waste sources, we measured their concentrations and isotopomer ratios (elemental isotope ratios and site-specific N isotope ratios in asymmetric molecules of NNO) in water and gas samples collected by an advanced treatment system in Tokyo. Although the estimated emissions of N(2)O and CH(4) from the system were found to be lower than those from the typical treatment systems reported before, water in biological reaction tanks was supersaturated with both gases. The concentration of N(2)O, produced mainly by nitrifier-denitrification as indicated by isotopomer ratios, was highest in the oxic tank (ca. 4000% saturation). The dissolved CH(4) concentration was highest in in-flow water (ca. 3000% saturation). It decreased gradually during treatment. Its carbon isotope ratio indicated that the decrease resulted from bacterial CH(4) oxidation and that microbial CH(4) production can occur in anaerobic and settling tanks.     

Soft Nanotubes with a Hydrophobic Channel Hybridized with Au Nanoparticles: Photothermal Dispersion/Aggregation Control of C60 in Water

Simple glycolipid N‐alkaroyl‐β‐D‐glucopyranosylamine 1(n) selectively self‐assembles into sheets in water, nanotubes in alcohols, and helical nanocoils in toluene. All self‐assemblies consist of bilayer membranes in which 1(n) packed in an interdigitated fashion. The outer surface of the sheet is covered with the hydrophilic glucose headgroup of 1(n), whereas those of the nanotube and helical nanocoil are covered with the hydrophobic alkyl‐chain tail of 1(n). Heat treatment of the nanotube in the presence of water induces a rearrangement of the molecular packing of the outermost surface that allows the nanotube to become an effective nanocontainer for the dispersion of fullerene (C60) in water, a result of the ability of the hydrophilic outer surface of the nanotube and the hydrophobic nanochannel to encapsulate C60. The nanotube also exhibits photothermal characteristics after being hybridized with Au nanoparticles (AuNPs). The photothermal effect of the AuNPs allows the nanotube to unfold its tubular morphology and leads to compulsive release of the encapsulated C60 to the bulk water. Application of other nanotubes with similar photostimulated transformation ability should facilitate control of the dispersion/aggregation of other carbon nanomaterials, functional aromatic compounds, and drugs with low solubility in water.     

Analyses of reactor building by 3D nonlinear FEM models considering basemat uplift for simultaneous horizontal and vertical ground motions

The nonlinear behavior of basemat uplift, which is an important point in seismic designs of nuclear power plants in Japan, has been investigated by arranging joint elements between the reactor building basemat and the soil on a three-dimensional (hereafter referred to as 3D) FEM model of the soil. However, the nonlinearity of the basemat uplift has been investigated separately from the nonlinearity of reactor buildings. These nonlinearities have yet to be taken into account simultaneously in past studies. In this paper, models of the building and the soil using 3D FEM elements with consideration to the nonlinearity of building materials as well as the nonlinearity of the basemat uplift were subjected. The behavior of the building's elements were investigated by carrying out seismic response analyses for horizontal ground motions only, as well as for simultaneous horizontal and vertical ground motions using these models. As a result, it was found that there was little difference in the horizontal response of the building between the horizontal input motions only and the simultaneous horizontal and vertical input motions. The effects of the vertical ground motions on the basemat uplift behavior which is represented by the ground contact ratio were also slight.     

Full-field optical coherence tomography by achromatic phase shifting with a rotating polarizer

We demonstrate two-dimensional detection optical coherence tomography (OCT) using achromatic phase shifting with a rotating polarizer. This phase shifting, which experiences a light beam with a cyclic change in its polarization state, is, in principle, independent of wavelength. We simulated the wavelength dependence of an achromatic phase shifter using Jones calculus and found that the achromatic region exceeded 145 nm when the deviation of the phase retardation was less than +/- 0.5 degrees. Using the achromatic phase shifter and a conventional phase-shift calculation method, we obtained en face OCT images of an onion at different depths. This method is effective to enhance the quality of OCT with an ultrabroad-spectrum light source.     

Ultrasonic effects on electroorganic processes: Part 24. Rate and saturated amount of the self-assembled adsorption of thiolate species on a gold surface

The rate and saturated amount of the self-assembled adsorption of aromatic thiolate species such as 4-pyridinethiolate and phenylthiolate on a polycrystalline gold surface were clearly increased under ultrasonic irradiation with an intensity higher than the ultrasonic cavitation threshold. On the other hand, in the case of the self-assembled adsorption of an aliphatic thiolate species like carboxy ethane thiolate, only the adsorption rate was increased under the irradiation, while the saturated amount was not. This fact suggests that the adsorption of carboxy ethane thiolate results in the most closely packed and ordered monolayer, regardless of ultrasonic irradiation.     

Evaluation of Crack Growth in Glass by Using Stress-Wave Fractography

Subcritical crack growth in glass shows three characteristic regions, depending on crack velocity. Among three regions, in region III, where water does not affect crack-growth behavior, the slope of the crack-growth curve can be correlated with the intrinsic nature of glass fracture. In this study, to measure the crack velocity in region III, a periodic stress wave was applied to produce fracture-surface markings in the double-cleavage-drilled compression specimen. The crack-growth data obtained were compared with results obtained via direct observation of the crack front. As a result, this method, by using stress-wave fractography, was found to be effective to obtain the crack-growth curve in region III.     

Finding division points for a time series corpus based on structural change point detection

This paper describes a method of finding the proper points for dividing a corpus with time series information to extract local and frequent keywords. Previous works have proposed the corpus separating method for extracting keywords from a corpus. However, this method divides a corpus at equal intervals so that it cannot consider the topic changes. The present paper utilizes the idea of the topic model and the topic extracted through latent Dirichlet allocation to consider the topic change. This paper identifies the points at which large topic changes occur to divide the corpus using structural change detection method. An experiment involving newspaper articles with 5-year topics confirm that the points at which the topics of each document change are detected to find the division points based on the idea of structural change point detection and our method is better than previous methods based on recall measure.     

Phase Separation in Gelling Silica–Organic Polymer Solution: Systems Containing Poly(sodium styrenesulfonate)

Phase separation which occurs in parallel to the hydrolysis and gelation of alkoxysilane solution containing poly(sodium styrenesulfonate) (NaPSS) has been investigated. Depending on the reaction conditions, gel morphologies such as isolated pores, particle aggregates, and interconnected continuous pores from 0.1 to 100 μm long have been observed. Time-resolved light scattering of gelling solution suggested the occurrence of spinodal phase separation through the polymerization of silica and the subsequent freezing of the developing structure by sol-gel transition. The effects of reaction parameters on the periodic size are explained mainly in terms of their influence on the "chemical cooling" rate which is determined by the polymerizatica rate of silica and the solubility of NaPSS in the reacting solution.