Synthesis of Nanohole‐Structured Single‐Crystalline Platinum Nanosheets Using Surfactant‐Liquid‐Crystals and their Electrochemical Characterization

Nanohole‐structured single‐crystalline Pt nanosheets have been synthesized by the borohydride reduction of Na₂PtCl₆ confined to the lyotropic liquid crystals (LLCs) of polyoxyethylene (20) sorbitan monooleate (Tween 80) with or without nonaethylene‐glycol (C₁₂EO₉). The Pt nanosheets of around 4–10 nm in central thickness and up to 500 nm or above in diameter have a number of hexagonal‐shaped nanoholes ∼1.8 nm wide. High‐resolution electron microscope images of the nanosheets showed atomic fringes with a spacing of 0.22 nm indicating that the nanosheets are crystallographically continuous through the nanoholed and non‐holed areas. The inner‐angle distributions for the hexagonal nanoholes indicate that the six sides of the nanoholes are walled with each two Pt (111), Pt (1 1) and Pt (010) planes. The formation mechanism of nanoholed Pt nanosheets is discussed on the basis of structural and compositional data for the resulting solids and their precursory LLCs, with the aid of similar nanohole growth observed for a Tween 80 free but oleic acid‐incorporated system. It is also demonstrated that the nanoholed Pt nanostructures loaded on carbon exhibit fairly high electrocatalytic activity for oxygen reduction reaction and a high performance as a cathode material for polymer‐electrolyte fuel cells, along with their extremely high thermostability revealed through the effect of electron‐irradiation.     

High-Speed TDM–WDM Techniques for Long-Haul Submarine Optical Amplifier Systems

Optical amplifier techniques have led to the installation of large-capacity submarine systems and further capacity increases seem likely. This paper reviews the FSA submarine system, which flexibly operates at both 2.5 and 10 Gb/s and offers maximum transmission capacity of 60 Gb/s for commercial use. The system configuration as well as its characteristics and upgradability will be introduced, including measurement results on time-division-multiplexing/wavelength-division-multiplexing (TDM–WDM) transmission at bit rates of 10 and 20 Gb/s using non-return-to-zero or soliton pulses. To further increase transmission capacity, TDM–WDM techniques that permit more than 10 Gb/s signal transmission in each data channel should be developed. Thus, pulse formats, which include non-return-to-zero, return-to-zero, or soliton pulses, and dispersion allocation in transmission fibers are significant issues. We introduce and discuss our recent results from high-speed (10 to 40 Gb/s) TDM–WDM signal transmission experiments with regard to the above aspects.     

Design and performance evaluation of amplifier modules in stackable ROADMs for low-cost CWDM access networks

Coarse wavelength division multiplexing (CWDM) network has proven to be promising lower cost network architecture for a significant cost advantage over dense wavelength division multiplexing due to the lower cost of lasers and the filters used in CWDM modules. A compatible amplifier module having bidirectional amplification capability was deployed for introducing inside stackable reconfigurable optical add/drop multiplexers in realizing large-scale CWDM networks. The amplifier module for use in the bidirectional IP transmission confirmed that the insertion losses of the nodes and the losses of the fibers connecting the nodes can be compensated effectively, allowing the network administrator to increase the number of nodes and fiber length of the network. However, the noise generated from the amplification due to amplified spontaneous emission must be considered in network design issues. In this paper, optical power penalties due to the bidirectional amplification were estimated by conducting experimentation on minimum detectable power of optical transceivers. After analyzing the power penalty issue, an IP-over-CWDM ring network was implemented and the performance of network was evaluated by monitoring the power and packet transmissions before and after the amplifier module was turned on.     

Role of mitochondria in the switch mechanism of the cell death mode from apoptosis to necrosis--studies on rho0 cells

Detailed mechanisms of the switch of the cell death mode from apoptosis to necrosis remain to be solved, although the intracellular level of ATP and that of free radicals have been postulated to be the major factors involved in the mechanisms. In the present study menadione (MEN)-induced cell injury processes were studied using rho0 cells derived from human osteosarcoma 143B cells and parental rho+ cells co-treated with inhibitors of electron transfer chain of mitochondria or oligomycin, an inhibitor of ATP synthesis. Treatment of rho+ cells with 100 microM MEN induced apoptosis, which reached the maximum at 6 h, and was followed by an abrupt decrease thereafter, while necrotic cells (NC) increased continuously when they were judged by Annexin V and PI double staining. On the other hand, MEN induced apoptotic and necrotic changes much faster in rho0 cells compared to rho+ cells. The frequency to find apoptotic cells (AP) in the former cells was distinctly smaller than that to find NC judged by Annexin V and PI double staining. Electron microscopically, a major population of rho0 cells treated with MEN for 6 h consisted of intermediate cells, and a small number of AP co-existed. At 9 h of the treatment intermediate cells were exclusively seen, and AP were hardly detected. When parental rho+ cells were treated with MEN in the presence of oligomycin or oligomycin plus antimycin A both apoptotic and necrotic changes of the cells were distinctly accelerated. The intracellular level of superoxide in rho0 cells continuously increased after the MEN treatment, whereas that of ATP remained distinctly low before and after the MEN treatment compared to that in rho+ cells. These data suggest that the intracellular level of superoxide may be a key factor controlling the switch from apoptosis to necrosis.     

A novel ferromagnetic thermo-stent for plaque stabilization that self-regulates the temperature

The purpose of this study is to investigate the vascular wall with a thermally self-regulating, cylindrical stent made of a low Curie temperature ferromagnetic alloy. Physiologic saline was circulated in the silicone model vessel implanted with the stent. The stent-temperature remained nearly constant for variable saline flows, saline temperatures, and magnetic flux densities. Stent implants of this type in human blood vessels could potentially enable thermotherapy and temperature determination without catheterization.     

DX centers in AlxGa1-xAs bulk alloy,AlAs/GaAs ordered,and disordered superlattices

Properties of theDX centers in Al_0.5Ga_0.5As bulk alloy (b-AL), (AlAs)₂ (GaSa)₂ ordered superlattice (o-SL) and (AlAs) _m (GaAs) _n disordered superlattice (d-SL) (m = 1, 2, 3,n = 1, 2, 3) with the same macroscopic composition were measured and compared. By deconvolution of deep level transient spectroscopy (DLTS) spectrum due to theDX center, we have found a decrease in the number of separate peaks in DLTS spectrum in an intentionally atomic ordered arrangement. Visiting Scholar of the Japan Society for the Promotion of Science. On leave from Department of Electrical Engineering, San Jose State University, San Jose, California 95192-0084, USA.     

Selective sorption of heavy metal thiocyanate complexes on crown ether resin

The sorption behavior of heavy metal thiocyanate complexes was investigated for dibenzo-18-crown-6 (DB18C6) resin and bis[2-(o-methoxyphenoxy)ethyl]ether (BMPE) resin. The DB18C6 resin showed a high sorption ability and the degree of zinc sorption increased significantly with thiocyanate concentration. This behavior was not observed for BMPE resin. The sorption behavior was influenced by the countercation species, and the degree of sorption of zinc ions showed the maximum when the potassium thiocyanate was used as a complexing salt. The sorbed species appear to be KZn(SCN)₃, K₂Zn(SCN)₄ in the potassium thiocyanate system, and Zn(SCN)₂ in the lithium thiocyanate system, respectively, according to analysis of the sorption equilibrium. Sodium and ammonium thiocyanate systems show an intermediate behavior of the two. The sorption selectivity for DB18C6 resin depended not only on the hydrophobic nature of heavy metal thiocyanate complexes but also on the stabilization of counter cation species with crown ether matrix, and the sorption selectively was found to be effectively controlled by countercation species according to the cation-chelation mechanism.     

Nanoimprinting using release-agent-coated resins

A fluorinated self-assembled monolayer (F-SAM) is mainly used as the antisticking layer. To prevent the F-SAM coated on the nanoimprint lithography (NIL) mold from deteriorating, we propose a new form of nanoimprinting using a release-agent-coated resin. The results from measuring the surface free energy and observations by scanning probe microscopy (SPM) confirmed that the surface free energy, frictional force, and adhesion force of the release-agent spray-coated polymethylmethacrylate (PMMA) were lower than those of PMMA. To prove the release-agent spray-coated PMMA had a releasing effect, we tried to undertake thermal nanoimprinting on it using a mold without F-SAM. The pattern was clearly imprinted on the resin without any signs of adhesion.     

InGaP//GaAs//c‐Si 3‐junction solar cells employing spectrum‐splitting system

In this work, we practically demonstrated spectrum‐splitting approach for advances in efficiency of photovoltaic cells. Firstly, a‐Si:H//c‐Si 2‐junction configuration was designed, which exhibited 24.4% efficiency with the spectrum splitting at 620 nm. Then, we improved the top cell property by employing InGaP cells instead of the a‐Si:H, resulting in an achievement of efficiency about 28.8%. In addition, we constructed 3‐junction spectrum‐splitting system with two optical splitters, and GaAs solar cells as middle cell. This InGaP//GaAs//c‐Si architecture was found to deliver 30.9% conversion efficiency. Our splitting system includes convex lenses for light concentration about 10 suns, which provided concentrated efficiency exceeding 33.0%. These results suggest that our demonstration of 3‐junction spectrum‐splitting approach can be a promising candidate for highly efficient photovoltaic technologies. Copyright © 2016 John Wiley & Sons, Ltd.     

Development of a high temperature-atmospheric pressure environmental cell for high-resolution TEM

An environmental cell for high-temperature, high-resolution transmission electron microscopy of nanomaterials in near atmospheric pressures is developed. The developed environmental cell is a side-entry type with built-in specimen-heating element and micropressure gauge. The relationship between the cell condition and the quality of the transmission electron microscopic (TEM) image and the diffraction pattern was examined experimentally and theoretically. By using the cell consisting of two electron-transparent silicon nitride thin films as the window material, the gas pressure inside the environmental cell is continuously controlled from 10(-5)?Pa to the atmospheric pressure in a high-vacuum TEM specimen chamber. TEM image resolutions of 0.23 and 0.31?nm were obtained using 15-nm-thick silicon nitride film windows with the pressure inside the cell being around 5?×?10(-5) and 1?×?10(4)?Pa, respectively.