A transparent sheet display by plastic MEMS

Abstract— A new type of color‐image display pixel based on MEMS (microelectromechanical systems) technology of plastic materials is presented. The mechanism for making color is optical interference using a Fabry‐Perot interferometer. A thin sheet of PEN (polyethylene naphthalate) with a metal half‐mirror was laminated over a glass or PEN substrate with an optical cavity inside. The electrostatically controlled deformation of the PEN film changes the color of the transmitting light by interference within the optical cavity. Color pixels of three primary colors (red, green, and blue) were successfully developed and demonstrated, with a driving voltage ranging from 80 to 120 Vdc. Thanks to the mechanical flexibility of the PEN films, the display could operate even when placed on a curved surface.     

Evaluation of cell wall binding domain of Staphylococcus aureus autolysin as affinity reagent for bacteria and its application to bacterial detection

We evaluated the cell wall binding (CWB) domain of Staphylococcus aureus autolysin as an affinity reagent for bacteria. A fusion of CWB domain and green fluorescent protein (CWB-GFP) bound to S. aureus with a dissociation constant of 15 nM. CWB-GFP bound to a wide range of gram-positive bacteria, but not to most gram-negative bacteria. We suspected that the outer membrane of gram-negative bacteria inhibits the access of CWB-GFP to peptidoglycan layer. Indeed, CWB-GFP bound to gram-negative bacteria when they were treated with benzalkonium chloride. Because CWB-GFP bound to the bacterial peptidoglycan layer, it appeared to be an effective affinity reagent for bacteria and CWB fusion with reporter proteins could be applied to detect bacteria. We also constructed a fusion of CWB and luciferase, which can be used for the rapid detection of bacteria.     

Electrochemical surface plasmon resonance measurement in a microliter volume flow cell for evaluating the affinity and catalytic activity of biomolecules

We developed an electrochemical surface plasmon resonance flow cell for the simultaneous measurement of the binding affinity and catalytic activity of bifunctional biomolecules. These measurements will be useful for evaluating the performance of such biomolecules as ribozyme and abzyme. The simultaneous measurements were performed on a gold surface modified with a multilayer consisting of poly-l-lysine and poly(styrene sulfonate) assembled with the layer-by-layer method using an enzyme-labeled monoclonal antibody as a model compound. We obtained the amount of immunocomplex formation from the surface plasmon resonance angle shift value by injecting the compound into the flow cell containing the multilayer modified with tumor necrosis factor-alpha. Then we compared this surface plasmon resonance result with that for the in situ electrochemical oxidation of p-aminophenol formed by the catalytic reaction of labeled enzyme on the same gold film. We were able to obtain a high correlation coefficient of 0.999 between the two responses. This is because the compound could be captured with high stability with a less than 3% coulometric response decrease in the catalyzed product in the multilayer whose thickness was easily controllable. In addition, we were able to measure the catalytic activity by coulometry and thus avoid the effect of peak broadening. We also report that the dephosphorylation activity of a bound compound could be estimated from the measurement results and an equation.     

A field life prediction model of electronic modules corroded by S8 gas released from rubber ducts in-vehicle engine rooms

A model which predict the field life of electronic modules corroded by S₈ gas in vehicle engine rooms is constructed. The in-vehicle module field life is predicted from the accelerated test results of module alone and the measured results of in-vehicle module field environment conditions. In the modules, a circuit substrate with Ag wiring is placed on a baseplate within a housing and sealed with silicone. The S₈ gas is produced by the release of the free sulphur of rubber ducts in engine room at the maximum temperature holding time after engine stop. This S₈ gas permeates the silicone seal and corrodes the Ag wiring. The ratio of the corroded part thickness to the initial thickness of the Ag wiring increases with the increase of the number of engine start/stop cycles. The calculated results coincide well with the observed results of the corrosion thickness in an actual vehicle.     

Rational Design of a Ratiometric Fluorescent Probe Based on Arene–Metal‐Ion Contact for Endogenous Hydrogen Sulfide Detection in Living Cells

We report the design and development of a fluorescent Cd^II ion complex that is capable of the ratiometric detection of H₂S in living cells. This probe exploits the metal‐ion‐induced emission red shift resulting from direct contact between the aromatic ring of a fluorophore and a metal ion (i.e., arene–metal‐ion or “AM” contact). The Cd^II complex displays a large emission blue shift upon interaction with H₂S as the Cd^II‐free ligand is released by the formation of cadmium sulfide. Screening of potential ligands and fluorophores led to the discovery of a pyronine‐type probe, 6? Cd^II, that generated a sensitive and rapid ratio value change upon interaction with H₂S, without interference from the glutathione that is abundant in the cell. The membrane‐impermeable 6? Cd^II was successfully translocated into live cells by using an oligo‐arginine peptide and pyrenebutylate as carriers. As such, 6? Cd^II was successfully applied to the ratiometric detection of both exogenous and endogenous H₂S produced by the enzymes in living cells, thus demonstrating the utility of 6? Cd^II in biological fluorescence analysis.     

N-terminal Cationic Modification of Linear Pyrrole-Imidazole Polyamide Improves Its Binding to DNA

Pyrrole-imidazole polyamides (PIPs) bind to double-stranded DNA (dsDNA) with varied sequence selectivity. We synthesized linear PIPs that can bind to narrow minor grooves of polypurine/polypyrimidine sequences and target long recognition sequences but have lower molecular weights than commonly used hairpin PIPs. We modified the N-terminus of linear PIPs using several groups, including β-alanine extension and acetyl capping. Melting curve analysis of dsDNA demonstrated that cationic modifications improved the binding affinity of the PIPs to the targeted dsDNA. In addition, circular dichroism assays revealed the characteristic spectra depending on the binding stoichiometry of the N-cationic linear PIP and dsDNA (1 : 1, monomeric; 2 : 1, dimeric). Surface plasmon resonance assays confirmed the high binding affinities of linear PIPs. These findings may aid in the design of effective linear PIPs.     

Thermal and thermo‐oxidative stability of thermoplastic polymer nanocomposites with arylated [60]fullerene derivatives

Nanocomposite films of polystyrene (PS) and poly(methyl methacrylate) (PMMA) were prepared by loading four variations of fullerenes such as pristine C₆₀, multiarylated [60]fullerenes with tolyl (tolyl‐C₆₀) and phenol groups (phenol‐C₆₀), and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM). The TGA analysis showed no appreciable change in their thermal and thermo‐oxidative stabilities for PS/tolyl‐C₆₀ and PS/phenol‐C₆₀ films, but significant improvement up to +45°C for PS/C₆₀ and PS/PCBM films even under air. The thermo‐oxidative stability of PMMA/phenol‐C₆₀ and PMMA/PCBM, however, exhibited slightly larger improvements over that of PMMA/C₆₀. We believe that the radical‐scavenging ability of π‐conjugative fullerenes and the dispersibility of fullerene–polymer combinations play key roles in these enhancements. We also found that optimal loading occurred at a relatively low content of fullerenes (0.4–0.8 wt%) probably because larger amounts may interfere with the morphological interaction of polymer chains which is essential for the thermal persistency of polymer. POLYM. COMPOS. 37:1143–1151, 2016. © 2014 Society of Plastics Engineers     

A highly accurate algorithm for SF6 leakage detection

Sulfur hexafluoride (SF₆) is widely used in high‐voltage applications such as gas‐insulated switchgear (GIS) because of its excellent arc‐quenching properties. The main drawback of SF₆ is that it is a strong greenhouse gas. Detecting small SF₆ leakages in GIS is very important to protect the environment and to prevent the failure of aged GIS. To detect SF₆ leakage, the gas pressure is measured and compensated by gas temperature. Usually, the temperature of the container surface is measured instead of the actual gas temperature. However, the temperature of the container surface is affected by ohmic heating of the internal components and by ambient temperature changes. These factors lead to a difference in temperature between the container surface and the gas inside the container, causing significant fluctuations in the compensated gas pressure. To remove such fluctuations, we have developed a computational fluid dynamics (CFD) transient model that simulates the correlation between the mean gas temperature inside the container and the container's surface temperature. The CFD simulation factors in the load current and ambient temperature to estimate the true temperature of the gas inside the container as accurately as possible. The mean gas temperature inside the container is obtained using CFD simulation and by measuring the surface temperature. The fluctuations in the compensated gas pressure were reduced from 2.4 to 0.48% by using the proposed algorithm based on pressure compensation with the mean gas temperature. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Note on heavy metal concentration in the aquatic environment of the Kitakyushu district in Japan, 1976–1977

The concentrations of cadmium, copper and lead, in the aquatic environment of the Kitakyushu district, Japan from 1976 to 1977 were investigated. This survey covered all rivers which run through the area, the bay, and the sea surrounding the district. The values obtained showed no significant heavy metal pollution, compared with values found in the literature for metal concentrations in other parts of the world, except for the concentrations of Dokai Bay. The concentrations of lead of the Dokai Bay showed an obviously high value, 40 μg 1⁻¹ (14–74 μg 1⁻¹, n = 32). This is due to the industrial activities of the surrounding area.     

Synthesis and functionality of poly(N-vinylalkylamide). X. A novel aqueous two-phase system based on thermosensitive polymers and dextran

The use of thermosensitive polymers in an aqueous two-phase system was studied. Poly(N-isopropylacrylamide) (PNIPAAm) and poly(N-vinylisobutyramide) (PNVIBA) were used as thermosensitive polymers. Both polymers could form aqueous two-phase with dextran, respectively. The phase diagrams of each system were successfully obtained. Using myoglobin as a model protein, a preliminary separation study was performed. The separation ability of both polymers was higher than that from the poly(ethylene glycol)-dextran system. Protein separation ability appeared to be related to the hydrophilic/hydrophobic balance of the polymers. Both PNVIBA and PNIPAAm rich phases maintained their thermosensitivity after two-phase formation. PNVIBA and PNIPAAm are useful as polymers for a functional aqueous two-phase system. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2545–2548, 1999