Crosslinked-Chelating Porous Sheet with High Dynamic Binding Capacity of Metal Ions

A crosslinked chelating porous sheet was prepared by cografting ethylene glycol dimethacrylate (EGDMA) with glycidyl methacrylate onto an electron-beam-irradiated porous polyethylene sheet, followed by the introduction of an iminodiacetate group. At a molar percentage of EGDMA of 1.0 mol%, the sheet exhibited a maximum dynamic binding capacity for copper ions of 0.93 mmol/g, while the equilibrium binding capacity remained the same (1.2 mmol/g) as that of a non-crosslinked chelating porous sheet. The crosslinking of the grafted chain causes copper ions to lower their diffusion rate along the sheet thickness driven by the gradient of the amount of copper ions adsorbed.     

Analysis of the Enhanced Stability of R(+)-Alpha Lipoic Acid by the Complex Formation with Cyclodextrins

R(+)-alpha lipoic acid (RALA) is one of the cofactors for mitochondrial enzymes and, therefore, plays a central role in energy metabolism. RALA is unstable when exposed to low pH or heat, and therefore, it is difficult to use enantiopure RALA as a pharma- and nutra-ceutical. In this study, we have aimed to stabilize RALA through complex formation with cyclodextrins (CDs). α-CD, β-CD and γ-CD were used for the formation of these RALA-CD complexes. We confirmed the complex formation using differential scanning calorimetry and showed by using HPLC analysis that complexed RALA is more stable than free RALA when subjected to humidity and high temperature or acidic pH conditions. Scanning electron microscopy studies showed that the particle size and shape differed depending on the cyclodextrin used for complexation. Further, the complexes of CD and RALA showed a different particle size distribution pattern compared with that of CD itself or that of the physical mixture of RALA and CD.     

Endogenous product differentiation and product R&D in spatial Cournot competition

We investigate in a spatial Cournot competition setting how much product research and development (R&D) investment firms make in order to differentiate their goods. The model features a location competition in the first stage, R&D competition in the second stage, and Cournot competition in the third stage. There are two differentiation methods in the model??spatial differentiation affecting the firm costs, and differentiation in the demand function affecting the demand levels. We find that comparing to the setting with no spatial connotation, the firms tend to invest less in product R&D. We also consider welfare implications. Although the firms employ maximum differentiation in equilibrium, there are cases in which welfare can be improved if the firms are to locate closer to each other.     

Deliverable‐power dependence on distribution‐line resistance and number of loads in low‐voltage DC distribution system

In this paper, we show that in a low‐voltage DC distribution system the deliverable power to a load has an upper limit P_lim due to the voltage instability at the receiving ends. On the basis of the previously derived concept of P_lim, we obtain the dependence of P_lim on the distribution line resistance R. In addition, we investigate the influence of the number of loads on P_lim. The result shows that a distribution line of lower R causes P_lim to be lower. This reduction in P_lim becomes more distinct for a larger number of loads. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Single-walled carbon nanotube growth from highly activated metal nanoparticles

We demonstrate that any metal, even gold, silver, and copper, can act as a catalyst for SWCNT synthesis in chemical vapor deposition (CVD). Metal nanoparticles 3 nm or less in diameter, introduced into CVD ambience immediately after heat treatment at 800-950 degrees C in air, produce SWCNTs. The activation method is effective for copper and various noble metals as well as for iron-family elements. This implies that any metal particle may produce SWCNTs when its size becomes 1-3 nm. In other words, carbon atoms can form SWCNTs in a self-assembling fashion on nanoparticles without the specific functions of iron-family elements.     

X-ray absorption of gold nanoparticles with thin silica shell

Silica-coated gold (Au) nanoparticles were prepared and their morphological and X-ray absorption properties were investigated. These core-shell type nanoparticles are very stable in aqueous media and may be suitable for an X-ray contrast agent in biological systems. Transmission electron micrographs confirmed well-separated and relatively homogeneous morphology of the nanoparticles in highly concentrated colloids. Peak position for Au plasmon resonance was red-shifted with increasing shell thickness. X-ray absorption by the colloids of silica-coated Au nanoparticles was stronger than that by those of silica-coated Agl nanoparticles, a recently investigated X-ray contrast agent, at similar experimental conditions.     

Measurement of heart rate variability and stress evaluation by using microwave reflectometric vital signal sensing

In this paper, we present two robust signal processing techniques for stress evaluation using a microwave reflectometric cardiopulmonary sensing instrument. These techniques enable the heart rate variability (HRV) to be recovered from measurements of body-surface dynamic motion, which is subsequently used for the stress evaluation. Specifically, two novel elements are introduced: one is a reconfiguration of the HRV from the cross-correlation function between a measurement signal and a template signal which is constructed by averaging periodic component over a measurement time. The other is a reconstruction of the HRV from the time variation of the heartbeat frequency; this is evaluated by a repetition of the maximum entropy method. These two signal processing techniques accomplish the reconstruction of the HRV, though they are completely different algorithms. For validations of our model, an experimental setup is presented and several sets of experimental data are analyzed using the two proposed signal processing techniques, which are subsequently used for the stress evaluation. The results presented herein are consistent with electrocardiogram data.     

Ultra-high-sensitive extraction-photometric determination of sodium ion using flow injection analysis with a chromogenic calix[4]arene derivative and a laser interferometric photothermal detector

A novel flow injection analysis (FIA) system for ultra-high-sensitive determination of Na(+), which involves laser interferometric photothermal equipment as the detector, was designed using a proton-dissociable chromogenic calix[4]arene derivative with a dinitrophenol moiety as the extraction-photometric reagent. The chromogenic calix[4]arene derivative showed an excellent extractability toward Na(+), which reflected the cation-complexing property of the tetraethyl ester derivative of calix[4]arene. As the calibration graph of the Na(+) concentration could be successfully obtained at the nanomolar level by this method, the proposed FIA system was found to be promising for highly sensitive determination of Na(+) in very dilute samples such as supply water and cooling water in power plants.     

Subwavelength resist patterning using interference exposure with a deep ultraviolet grating mask: Bragg angle incidence versus normal incidence

Interference lithography using a deep-ultraviolet (DUV) laser is instrumental in the manufacture of subwavelength patterns used at visible wavelengths. We investigated a grating mask strategy for exposure in terms of how to set and illuminate masks. To obtain high aspect ratio patterns, high fringe visibility, and high exposure uniformity are essential, and for that purpose the use of only two beams with liquid immersion is necessary but not sufficient. It needs to be addressed whether the grating should face air or liquid to achieve index matching without affecting its beam-splitting properties. Currently, the most feasible solution to produce sub-200 nm periods requires the use of a fused-silica grating under Bragg geometry (not normal incidence geometry) and filling the gap between the grating and resist with a high-index liquid.     

Graphene growth on a Pt(111) substrate by surface segregation and precipitation

We report on the fabrication of a sizable graphene sheet on a carbon-doped Pt(111) substrate through surface segregation and precipitation. Scanning Auger electron spectroscopy (AES) reveals that the graphene covered more than 98% of the substrate surface. Our graphene consists of single-layer graphene across the substrate with fractions of several micrometer wide bi- and tri-layer graphene islands. We also show that the number of graphene layers can be precisely determined by analyzing AES data. While Raman spectroscopy is usually used to study graphene on SiO?, we show that AES is a powerful tool to characterize graphene grown on metal substrates.