Corrosion Behavior of Sialon Ceramics in Supercritical Water

The corrosion behavior of sialon ceramics was investigated in supercritical water at 450°C under 45 MPa for 2–50 h. α-sialon exhibited better corrosion resistance than β-sialon and α/β-sialon. Pitting corrosion with the formation of corrosion products was observed in the case of β-sialon and α/β-sialon. By contrast, the corrosion behavior of α-sialon was characterized by uniform corrosion with the formation of corrosion products. The degree of strength deterioration was strongly dependent on the corrosion morphology. The bending strength of α-sialon after corrosion for 30 h was about 90% of its initial strength, while the strength of β-sialon decreased to 65% of its original strength.     

Oblique Promax Rotation Applied to the Solutions in Multiple Correspondence Analysis

There are many approaches to formulate multiple correspondence analysis of multi-item categorical data. A lower-rank approximation approach gives the freedom for the oblique rotation of axes. In the current paper, we apply the oblique rotation of axes to a variable-by-dimension matrix to arrive at simple structure. This matrix is defined in either of two different manners, that is, by treating categories as variables or, alternatively, by treating items as variables. For each of these two options, the standardized inner products between dimensions and variables are used as the elements of the component structure matrix. We adopt a promax method for the oblique rotation. In this method, scores are rotated in such a way that the above matrix is matched with the target matrix obtained from the result of the varimax rotation.

     

The BC-chain method for representing combinators in linear space

Turner’s combinator implementation (1979) of functional programs requires the memory space of size Ω(n ²) in the worst case for translating given lambda expressions of lengthn to combinator graphs. In this paper a new idea named the BC-chain method for transferring actual arguments to variables is presented. We show that the BC-chain method requires onlyO(n) space for the translation. The basic idea is to group together into a single entity a sequence of combinatorsB, B′, C andC′, for a variable, which appear consecutively along a path in the combinator graph. We formulate two reduction algorithms in the new representation. The first algorithm naively simulates the original normal order reduction, while the second algorithm simulates it in constant time per unit operation of the original reduction. Another reduction method is also suggested, and a technique for practical implementation is briefly mentioned.     

Er3+ ‐Doped Y2O3 Nanophosphors for Near‐Infrared Fluorescence Bioimaging Applications

Rare‐earth‐doped ceramic nanophosphor (RED‐CNP) materials are promising near‐infrared (NIR) fluorescence bioimaging (FBI) agents that can overcome problems of currently used organic dyes including photobleaching, phototoxicity, and light scattering. Here, we report a NIR–NIR bioimaging system by using NIR emission at 1550 nm under 980 nm excitation which can allow a deeper penetration depth into biological tissues than ultraviolet or visible light excitation. In this study, erbium‐doped yttrium oxide nanoparticles (Er³⁺:Y₂O₃) with an average particle size of 100 and 500 nm were synthesized by surfactant‐assisted homogeneous precipitation method. NIR emission properties of Er³⁺:Y₂O₃ were investigated under 980 nm excitation. The surface of Er³⁺:Y₂O₃ was electrostatically PEGylated using poly (ethylene glycol)‐b‐poly(acrylic acid) (PEG‐b‐PAAc) block copolymer to improve the chemical durability and dispersion stability of Er³⁺:Y₂O₃ under physiological conditions. In vitro cytotoxic effects of bare and PEG‐b‐PAAc‐modified Er³⁺:Y₂O₃ were investigated by incubation with mouse macrophage cells (J774). Microscopic and macroscopic FBI were demonstrated in vivo by injection of bare or PEG‐b‐PAAc‐modified Er³⁺:Y₂O₃ into C57BL/6 mice. The NIR fluorescence images showed that PEG‐b‐PAAc modification significantly reduced the agglomeration of Er³⁺:Y₂O₃ in mice and enhanced the distribution of Er³⁺:Y₂O₃.     

Quantitative determination of colored oily soil adhering to metal surface using digital image data

A method for calculating the amount of colored soil on a flat metal surface from digital image data was examined. Round samples cut out of SUS tape were soiled with oily soil mixed with sudan III, placed in sample bottles, and washed using a tube rotator. Images of the samples before and after the washing process were captured using a CCD camera and the image data were processed by a computer. The shine from the metallic surface was controlled by using indirect lighting. It was necessary to diminish the effect of the substrate's color, and to this end, we attempted to apply linear and non-linear color correction procedures. We found that the use of gamma correction after linear correction to remove the effect of the metal surface color was the most accurate quantitative method. Additionally, we conducted a washing test with commercial detergents using this quantitative method for image data and found that the removal process for the greasy soil from the metal surface could be expressed as a first-order reaction.     

Development of a mass-producible on-chip plasmonic nanohole array biosensor

We have developed a polymer film based plasmonic device whose optical properties are tuned for measuring biological samples. The device has a circular nanohole array structure fabricated with a nanoimprint technique using a UV curable polymer, and then gold thin film is deposited by electron beam deposition. Therefore, the device is mass-producible, which is also very important for bioaffinity sensors. First the gold film thickness and hole depth were optimized to obtain the maximum dip shift for the reflection spectra. The dip shift is equivalent to the sensitivity to refractive index changes at the plasmonic device surface. We also calculated the variation in reflection spectra by changing the above conditions using the finite-difference time domain method, and we obtained agreement between the theoretical and experimental curves. The nanohole periodicity was adjusted from 400 to 900 nm to make it possible to perform measurements in the visible wavelength region to measure the aqueous samples with less optical absorption. The tuned bottom filled gold nanohole array was incorporated in a microfluidic device covered with a PDMS based microchannel that was 2 mm wide and 20 μm deep. As a proof of concept, the device was used to detect TNF-α by employing a direct immunochemical reaction on the plasmonic array, and a detection limit of 21 ng mL(-1) was obtained by amplification with colloidal gold labeling instead of enzymatic amplification.     

Electrochemical oxidation of ethylene glycol on Pt-based catalysts in alkaline solutions and quantitative analysis of intermediate products

Electrocatalytic activities of Pt/C, Pt-Ru/C, and Pt-Ni/C for the oxidation of ethylene glycol in a basic solution are evaluated by cyclic voltammetry and quasi-steady state polarization. Based on the results of Tafel slopes from quasi-steady state polarization, the catalytic activities for ethylene glycol oxidation are in the order of Pt-Ru/C > Pt-Ni/C > Pt/C. The analysis of intermediate products for ethylene glycol oxidation by higher performance liquid chromatograph (HPLC) demonstrates that the degree of ethylene glycol oxidation is dependent on catalysts. Pt-Ru/C shows the highest current densities for ethylene glycol oxidation, but shows lower fuel utilization. On the other hand, Pt-Ni/C shows higher ability to cleavage C–C bonds, but is suffered from catalyst poisoning. To improve the tolerance for catalyst poisoning, we construct a novel Pt-Ni-SnO₂/C catalyst, compare its catalytic activities, and evaluate the intermediates. Pt-Ni-SnO₂/C shows superior catalytic activities for ethylene glycol oxidation, resulting in the highest degree of complete electro-oxidation of ethylene glycol to CO₂.     

Assembly of untreated single-walled carbon nanotubes at a liquid-liquid interface

Untreated single-walled carbon nanotubes (SWCNTs) were assembled at a liquid-liquid interface to form an ultrathin film. The SWCNTs were dispersed into water using sodium dodecyl sulfate (SDS) as a solubilizing agent. Then, hexane was added to the dispersion to create a liquid-liquid interface. The SWCNTs were assembled at the interface to form a smooth ultrathin film when ethanol was added to the SWCNT water dispersion/hexane solution. The assembly mechanism was considered to be caused by the decreased wettability of SDS-coated SWCNT during the addition of ethanol because of desorption of SDS from the SWCNT surface. The assembly was remarkably robust and easily transferable to substrates. An AFM image of the film transferred onto a silicon substrate shows a closely packed uniform film of 3-8 nm thickness. The SWCNT ultrathin film showed high transparency of ca. 97% with an electrical conductivity of 71.4 S/cm. Fabrication processing was carried out in ambient conditions, thereby making it an attractive application for use in flexible electric devices.     

Characterization of microseparator/classifier with a simple arc microchannel

Experimentally characterized is a novel microseparator/classifier, whose functional part is an arc microchannel with a width of 200 μm, depth of 150 μm, and radius of 20 mm. First, a unique separation principle due to shear‐induced lift force is visually demonstrated with neutrally buoyant particles. The device performance is subsequently measured in terms of cut size, separation sharpness, and feed pressure for slightly denser acrylic particles. Compared with representative hydrocyclones, the present device is found to attain significantly smaller cut size at comparable feed pressure, and vice versa. It is finally shown that the device performance remains highest below a critical Stokes number because of no or negligible shear‐induced interparticle collisions. It is concluded that the device is to operate with a high efficiency based on the proposed Stokes number. © 2008 American Institute of Chemical Engineers AIChE J, 2009     

Determining double-bond positions in monoenoic 2-hydroxy fatty acids of glucosylceramides by gas chromatography-mass spectrometry

We applied a gas chromatography-mass spectrometry (GC-MS) method using dimethyl disulfide (DMDS) adducts and were able to determine the double-bond positions in monounsaturated 2-hydroxy fatty acids (2-HFA). 2-HFA methyl esters, prepared from the hydrolysate ofArabidopsis thaliana leaf glucosylceramides, were acetylated and methylthiolated. GC-MS analysis of the resulting DMDS adducts showed simple mass spectra with recognizable molecular ions and a series of key fragment ions indicating the original double-bond positions in the aliphatic chain. Based on this GC-MS elucidation, we confirmed thatArabidopsis leaf glucosylceramides have C₂₂, C₂₃, C₂₄, C₂₅, and C₂₆ chain length 2-HFA with monounsaturation, and all their double bonds are placed at the n−9 position. This procedure is simple, time efficient, and highly sensitive.