Decoration of glassy carbon surfaces with dendrimer-encapsulated nanoparticles with a view to constructing bifunctional nanostructures

We demonstrate a method for constructing bifunctional nanostructures, which conjugate biochemical and electrocatalytic activities, on glassy carbon surfaces by decorating the carbon surfaces with both biologically active glucose oxidases and size-monodisperse Pt nanoparticles (less than 2 nm in diameter) utilizing only a single dendrimer layer.     

Influence of TiO2 nanotube morphology and TiCl4 treatment on the charge transfer in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) were fabricated using TiO₂ nanoparticles (NPs), TiO₂ nanotube arrays (NTAs), and surface-modified NTAs with a TiCl₄ treatment. The photovoltaic efficiencies of the DSSCs using TiO₂ NP, NTA, and TiCl₄-treated NTA electrodes are 4.25, 4.74, and 7.47 %, respectively. The highest performance was observed with a TiCl₄-treated TiO₂ NTA photoanode, although in the case of the latter two electrodes, the amounts of N719 dye adsorbed were similar and 68 % of that of the NP electrode. Electrochemical impedance measurements show that the overall resistance, including the charge–transfer resistance, was smaller with NTA morphologies than with NP morphologies. We suggest that a different electron transfer mechanism along the one-dimensional nanostructure of the TiO₂ NTAs contributes to the smaller charge–transfer resistance, resulting in a higher short circuit current (J _sc), even at lower dye adsorption. Furthermore, the TiCl₄-treated NTAs showed even smaller charge–transfer resistance, resulting in the highest J _sc value, because the downward shift in the conduction band edge improves the electron injection efficiency from the excited dye into the TiCl₄-treated TiO₂ electrodes.     

Small sample properties of generalized logit model estimators with bootstrap

The generalized logit model of nominal type with random regressors is studied for bootstrapping. We assess the accuracy of some estimators for our generalized logit model, using a Monte Carlo simulation. That is, we study the finite sample properties containing the consistency and asymptotic normality of the maximum likelihood estimators. Also, we compare Newton Raphson algorithm with BHHH algorithm.     

Lewis-type catalytic activity of direct incorporated Zr- and Sn-SBA-16 catalysts

Metal incorporation into nanoporous materials could give Lewis acid sites through the framework substitution of silica matrix, which are supposed to be in tetrahedral substitution of silica. In this work, Zr- and Sn-incorporated SBA-16 were directly synthesized by the microwave synthesis method. These microwave synthesized Zr- and Sn-incorporated mesoporous silica materials were applied in activation of ketones by Lewis acid sites to catalyze Meerwein-Ponndorf-Verly reduction of cyclohexanone and Baeyer-Villiger oxidation of adamantanone, respectively. Optimum incorporated Zr- and Sn-species gave almost 100% selectivity with high activity onto corresponding alcohol and lactone, respectively.     

Off-peak saturation effects of beam-plasma instability

For beam-plasma instability in the absence of a magnetic field, hybrid simulations produce almost identical results to those of particle simulations (both agree with linear and nonlinear analyses), but with much reduced computing cost and noise level. With the verification by simulations, it is shown that the saturation level is very strongly influenced by the discrete wave number spectrum, sometimes giving different, by an order of magnitude, results by choosing slightly different off-peak (in growth rate curve) parameters, which must be considered in most simulations (whether hybrid or particle or whether magnetized or unmagnetized)     

Future Direction for a Diffusion Barrier in Future High-Density Volatile and Nonvolatile Memory Devices

This article reviews the current status of high-density capacitor for volatile memory devices. The dielectric properties for both the Ta₂O₅ film and the (Ba, Sr)TiO₃ (BST) dielectric materials using either the metal organic chemical vapor deposition (MOCVD) or the atomic layer deposition (ALD) are reviewed briefly. New challenges of dielectric material for the next generation, and serious problems emerged during integration to date using Ta₂O₅ and BST. The material characteristics of many electrode materials for the high dielectric materials are introduced. We present the basic properties and integration issued for MOCVD-ruthenium (Ru). The second part of this review summarized the failure mechanisms from barrier properties of previously reported diffusion barriers and emphasizes new design concepts of diffusion barrier for high-density memory devices. Finally, the future direction for a diffusion barrier to advance high-density memory capacitors is suggested.     

Enhancement of long-term stability of pentacene thin-film transistors encapsulated with transparent SnO2

The long-term stability of pentacene thin-film transistors (TFTs) encapsulated with a transparent SnO₂ thin-film prepared by ion beam-assisted deposition (IBAD) was investigated. After encapsulation process, our organic thin-film transistors (OTFTs) showed somewhat degraded field-effect mobility of 0.5 cm²/(V s) that was initially 0.62 cm²/(V s), when a buffer layer of thermally evaporated 100 nm SnO₂ film had been deposited prior to IBAD process. However, the mobility was surprisingly sustained up to 1 month and then gradually degraded down to 0.35 cm²/(V s) which was still three times higher than that of the OTFT without any encapsulation layer after 100 days in air ambient. The encapsulated OTFTs also exhibited superior on/off current ratio of over 10⁵ to that of the unprotected devices (∼10⁴) which was reduced from ∼10⁶ before aging. Therefore, the enhanced long-term stability of our encapsulated OTFTs should be attributed to well protection of permeation of H₂O and O₂ into the devices by the IBAD SnO₂ thin-film which could be used as an effective inorganic gas barrier for transparent organic electronic devices.     

Oriented polymers: A transfer matrix calculation

Based on transfer matrix techniques and finite-size scaling, we study the oriented polymer (self-avoiding walk) with nearest neighbor interaction. In the repulsive regime, various critical exponents are computed and compared with exact values predicted recently. The polymer is also found to undergo a spiral transition for sufficiently strong attractive interaction. The fractal dimension of the polymer is computed in the repulsive and attractive regimes and at the spiral transition point. The later is found to be different from that at the collapse transition of the ordinary self-avoiding walk.     

Stable single-mode operation of a Q-switched laser by a simple resonator length control technique

A simple extension to the technique of “pre-lase” Q-switching ensures that a TEM₀₀ mode, Q-switched NdYAG laser produces single longitudinal mode oscillation on every shot.