Layer-by-layer self-assembled mutilayer films of gold nanoparticles for surface-assisted laser desorption/ionization mass spectrometry

Layer-by-layer (LBL) self-assembled multilayer films of gold nanoparticles (AuNPs) on a silicon wafer were demonstrated to be promising substrates for surface-assisted laser desorption/ionization (SALDI) mass spectrometry (MS) of peptides and environmental pollutants for the first time. LBL multilayer films, (AuNPs/PAHC)n, consisting of alternating layers of ammonium citrate capped AuNPs and poly(allylamine hydrochloride) (PAHC) were prepared on a silicon surface. Silicon plates with aggregated AuNPs were more suitable than those with dispersed AuNPs for the SALDI-MS of peptides. The number of particle layers had a significant effect on the laser desorption/ionization of angiotensin I; the peak intensity of the peptide (molecular ion amount) increased with an increase in the number of layers of AuNPs. As a result, the (AuNPs/PAHC)5 multilayer films increased the sensitivity of the angiotensin I to subfemtomoles and raised the useful analyte mass range, thus making it possible to detect small proteins (a 12 kDa cytochrome c). The signal enhancement when using (AuNPs/PAHC)5 may be due to (i) the high absorption of the UV laser light at 337 nm by the AuNP layers, (ii) the low thermal conductivity due to the AuNPs being covered with a thin monolayer of PAHC, and (iii) the increase in the surface roughness (approximately 100 nm) with the number of AuNP layers. Thus, laser-induced rapid high heating of AuNPs for effective desorption/ionization of peptides is possible. In addition, it was found that (AuNPs/PAHC)5 could be used to extract environmental pollutants (pyrene and dimethyldistearylammonium chloride) from very dilute aqueous solutions with concentrations less than 10(-10) mg/mL, and the analytes trapped in the LBL film could be identified by introducing the film directly into the SALDI mass spectrometer without needing to elute the analytes out of the film.     

下一代光交换网络的智能控制平面技术

For the next generation optical switching networks, the intelligent control plane is a key enabling technique. In this paper, we review our recent research activities related to Generalized Multi-Protocol Label Switching ( GMPLS ) and OpenFlow-based control planes for both Wavelength Switched Optical Networks (WSON) and Elastic Optical Networks (EON).     

Oxidation of Low-Oxygen Silicon Carbide Fibers (Hi-Nicalon) in Carbon Dioxide

Polycarbosilane-derived low-oxygen SiC fibers, Hi-Nicalon, were heat-treated for 36 ks at temperatures from 1273 to 1773 K in CO₂ gas. The oxidation of the fibers was investigated through the examination of mass change, crystal phase, resistivity, morphology, and tensile strength. The mass gain, growth of β-SiC crystallites, reduction of resistivity of the fiber core, and formation of protective SiO₂ film were observed for the fibers after heat treatment in CO₂ gas. SiO₂ film crystallized into cristobalite above 1573 K. Despite the low oxygen potential of CO₂ gas ( p _O2= 1.22 Pa at 1273 K − 1.78 × 10² Pa at 1773 K), Hi-Nicalon fibers were passively oxidized at a high rate. There was a large loss of tensile strength in the as-oxidized state at higher temperatures because of imperfections in the SiO₂ film. On the other hand, the fiber cores showed better strength retention even after oxidation at 1773 K.     

Oxygen permeation properties and surface modification of acceptor-doped CeO2/MnFe2O4 composites

The preparation and oxygen permeation properties of the (Ce_0.8Pr_0.2)O_2−δ − x vol% MnFe₂O₄ composites, where x = 0 to 35, have been investigated. The samples were prepared by the Pechini method. In the case of Ce_0.8Pr_0.2O_2−δ, an oxygen flux density of 6 μmol⋅cm⁻²⋅s⁻¹ (L = 0.0247 cm) and the maximum methane conversion of 50% were attained at 1000^∘C. Unlike composites consisting of Gd-doped CeO₂ and MnFe₂O₄, the oxygen permeability of the (Ce_0.8Pr_0.2)O_2−δ – x vol% MnFe₂O₄ composites was almost constant regardless of the volume fraction of MnFe₂O₄; however, the optimum volume fraction of MnFe₂O₄ was determined to be 5 to 25 in the context of the chemical and mechanical stabilities under methane conversion atmosphere. In addition, the surface modification of the (Ce_0.8Gd_0.2)O_2−δ – 15 vol% MnFe₂O₄ composite was performed by using the FePt nanoparticles. The catalyst loading of 2.8 mg/cm² on the both side of the 0.3 mm-thick (Ce_0.8Gd_0.2)O_2−δ – 15vol% MnFe₂O₄ composite increased the oxygen flux density from 0.30 to 0.76 μmol⋅cm⁻²⋅s⁻¹ in the case of He/air gradients; however, the effect seems to be reduced in the case of high oxygen flux density caused by a large pO₂ gradient. Moreover, the Langmuir-Blodgett film of the FePt nanoparticles were successfully prepared on the tape-cast (Ce_0.8Gd_0.2)O_2−δ – 15vol% MnFe₂O₄ composite. Hydrophobic treatments for the surface of the composite were crucial to achieve high transfer ratio for the deposition of the LB film.     

Synthesis and photophysical properties of structural isomers of novel 2,10-disubstituted benzofuro[2,3-e]naphthoxazole-type fluorescent dyes

Structural isomers of novel 2,10-disubstituted benzofuro[2,3-e]naphthoxazole fluorescent dyes have been synthesized. The phtophysical properties have been investigated in solution and in the solid state. The absorption and fluorescence intensities of the naphth[1,2-d]oxazoles are much stronger than those of the naphth[2,1-d]oxazoles in solution. Moreover, in the solid state, the emission intensities of the former are typically much stronger than those of latter isomers. To understand the differences in photophysical properties, semi-empirical molecular orbital calculations and the X-ray crystallographic analyses have been performed.     

Generative adversarial network for road damage detection

Machine learning can produce promising results when sufficient training data are available; however, infrastructure inspections typically do not provide sufficient training data for road damage. Given the differences in the environment, the type of road damage and the degree of its progress can vary from structure to structure. The use of generative models, such as a generative adversarial network (GAN) or a variational autoencoder, makes it possible to generate a pseudoimage that cannot be distinguished from a real one. Combining a progressive growing GAN along with Poisson blending artificially generates road damage images that can be used as new training data to improve the accuracy of road damage detection. The addition of a synthesized road damage image to the training data improves the F‐measure by 5% and 2% when the number of original images is small and relatively large, respectively. All of the results and the new Road Damage Dataset 2019 are publicly available ( https://github.com/sekilab/RoadDamageDetector ).     

Improved High-Q Dielectric Resonator with Complex Perovskite Structure

Microwave characteristics of the system Ba(Zn_1/3Ta_2/3)O₃-BaZrO₃ were investigated. Ba(Zn,Ta)O₃ has a perovskite pseudocell and hexagonal superstructure; the superstructure was not formed after addition of BaZrO₃. Both sintering and crystallization of Ba(Zn,Ta)O₃-BaZrO₃ were accelerated compared to those of Ba(Zn,Ta)O₃ alone, and the microwave Q value was also improved. The material optimized for the dielectric resonator, Ba(Ni,Ta)O₃-Ba(Zr,Zn,Ta)O₃, has a dielectric constant of 30, Q value of 10000 at 10 GHz, and temperature coeficient of resonant frequency of 0 ppm/°C.     

Generation and Progress Behavior of Strain-Induced Abnormally Large Grains in Superalloy 718

Metallurgical and Materials Transactions A - Herein, the behavior associated with strain-induced abnormally large grains in superalloy 718 was investigated using compression testing and subsequent...     

Feedback enlargement of stability radius by nondifferentiable optimization

In controller design of dynamical systems, it is desirable that the controllers guarantee the stability for not only nominal plants but also perturbed ones, because the plant models may have some uncertainties in their parameters. By this motivation, several studies for the robust controller design have been conducted. In this paper, a feedback controller design method is considered, which achieves enlarging the degree of robust stability for the linear SISO closed‐loop systems. Choosing stability radius for the plant parameters as the degree of robust stability, and regarding this as an object function, we formulated this maximization as an optimization problem with constraints coming from prescribed pole placement. The difficulty of this formulation is that while pole placements give linear constraints, the object function is not a smooth one, which calls for an optimization technique for nondifferentiable functions. To cope with this, we successfully used the bundle method. We show some numerical examples to illustrate our proposed design method. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(3): 55–61, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20623