Multicolor saccharide-sensing chips based on boronic acid-containing thin films showing stepwise release and binding of dyes

A novel saccharide sensor that shows a distinct color change resembling a "traffic signal" was developed. By copolymerizing a boronic acid monomer and an amine monomer on a glass plate, a boronic acid-containing thin film was obtained. After adsorbing anionic blue and yellow dyes, the thin film was immersed in aqueous saccharide solutions containing a cationic red dye. As saccharide concentration increased, the thin film changed its color from green to red via yellow. Origin of the distinct color change was attributed to a stepwise release and binding of dyes.     

Unified approach to catechin hetero-oligomers: first total synthesis of trimer EZ-EG-CA isolated from Ziziphus jujuba

A catechin hetero-trimer isolated from Ziziphus jujuba has been synthesized. Among three constituent monomers, (-)-epiafzelechin and (-)-epigallocatechin were prepared by de novo synthesis. Trimer formation relied on the unified approach to oligomers based on the bromo-capping and the orthogonal activation, reaching the reported structure of the natural product.     

Evaluation of Sensitivity of Fluorescence-Based Asbestos Detection by Correlative Microscopy

Fluorescence microscopy (FM) has recently been applied to the detection of airborne asbestos fibers that can cause asbestosis, mesothelioma and lung cancer. In our previous studies, we discovered that the E. coli protein DksA specifically binds to the most commonly used type of asbestos, chrysotile. We also demonstrated that fluorescent-labeled DksA enabled far more specific and sensitive detection of airborne asbestos fibers than conventional phase contrast microscopy (PCM). However, the actual diameter of the thinnest asbestos fibers visualized under the FM platform was unclear, as their dimensions were below the resolution of optical microscopy. Here, we used correlative microscopy (scanning electron microscopy [SEM] in combination with FM) to measure the actual diameters of asbestos fibers visualized under the FM platform with fluorescent-labeled DksA as a probe. Our analysis revealed that FM offers sufficient sensitivity to detect chrysotile fibrils as thin as 30–35 nm. We therefore conclude that as an analytical method, FM has the potential to detect all countable asbestos fibers in air samples, thus approaching the sensitivity of SEM. By visualizing thin asbestos fibers at approximately tenfold lower magnifications, FM enables markedly more rapid counting of fibers than SEM. Thus, fluorescence microscopy represents an advanced analytical tool for asbestos detection and monitoring.     

Wind tunnel test of Japanese arrows with the JAXA 60-cm magnetic suspension and balance system

In order to understand the aerodynamic properties of Japanese arrows, several types of shafts without fletching and various types of Japanese arrows were examined in a low-speed wind tunnel equipped with the JAXA 60-cm magnetic suspension and balance system. The main component of drag acting on the shaft is viscous drag from the boundary layer. This viscous drag can be evaluated analytically. A simple new method to estimate the effects of fletching on the lift of the arrow was proposed in which we found that lift is proportional to the angle of attack of the arrow but not to the rotation speed or angle. Time history results for the lift on rotating arrows in the magnetic suspension and balance system indicate that this method effectively estimates the lift on an actual rotating arrow in flight. The lift and pitching moment were mainly generated by fletching, and the drag from the fletching was similar in magnitude to that of the arrow shaft. For Japanese bamboo arrows tested with a field point, the drag, lift, and pitching moment coefficients were evaluated to be in the ranges of 3.5?C3.7, 0.4?C0.8, and ?0.15 to ?0.25, respectively, at Reynolds numbers of an arrow in flight.     

First-principles supercell calculations for simulating a shallow donor state in Si

We present first-principles simulations of As-doped Si carried out using several cubic supercells of up to 10 648 atoms. The 1s As donor level in each supercell splits into three states, which have A₁, T₂, and E symmetries, respectively. The 1s(A₁) wavefunction is well converged in the largest cell, and its spread is close to those of the effective-mass theories. However, the calculated binding energies are smaller than experimental values. This discrepancy would be due to the self-interaction error within the approximated exchange-correlation density functional used in this calculation. Therefore, we also show perturbative calculations based on an impurity potential without the self-interaction error to estimate the binding energies of the 1s(A₁) donor state. The estimated binding energy in the largest supercell agrees well with the experimental value.     

Electrochemical Detection of Triglycerides Based on an Enzymatic Reaction and Electrocatalytic Oxidation with Nortropine‐N‐oxyl

This work investigated a simple triglycerides (TGs) detection method combining an enzymatic reaction, using only lipase, and the electrocatalytic oxidation of glycerol with nortropine‐N‐oxyl (NNO). Tributyrin was employed as a model TG. In this method, TGs are degraded by lipase to glycerol and fatty acids, after which the glycerol reacts with NNO. Preliminary cyclic voltammetry trials demonstrated that the anodic peak current increased along with the glycerol concentration, giving currents of 53.2 and 97.3 μA (at +0.6 V vs. Ag/AgCl) in response to 10 and 100 mM glycerol, respectively. Amperometry confirmed the same response during constant potential electrolysis at+0.6 V vs. Ag/AgCl. This behavior was also observed in a system incorporating tributyrin and lipase, with increases in current proportional to the tributyrin concentration over the range of 0.1 to 10 mM.     

Total Synthesis of Carthamin,a Traditional Natural Red Pigment

The first total synthesis of carthamin ( 3 ), a historic natural red pigment, has been achieved. The molecular structure was efficiently constructed by assembling two equivalents of the in situ generated lithiated monomers and triisopropyl orthoformate. This synthesis confirms the structure proposed in 1996.     

Electroluminescence of a bichromophoric molecule with a benzoxyazolylcoumarin and carbazole moiety

The electroluminescent properties of a bichromophoric molecule in which a benzoxyazolylcoumarin and carbazole moiety is combined with 1,2-ethylene linkage, i.e. 3-(2-benzoxyazolyl)-7-[2-(9-carbazolyl)ethoxy]-coumarin (CmCz), were investigated. CmCz exhibits fluorescence of different colors in a solid state and solution. Two types of device were made. One consisted of a vacuum vapor-deposited film of CmCz as an emission layer to utilize fluorescence in the solid state; the second consisted of a spin-cast film doped with CmCz as an emission material to utilize fluorescence in the solution. The device with a vapor-deposited CmCz film between electrodes shows a green emission with a luminance of less than 10⁻² cd/m². The multiple layer device in which the CmCz film was sandwiched between a hole transport layer and electron transport layer showed a green emission whose spectrum is identical to the photoluminescent spectrum in the vapor-deposited CmCz film. A maximum luminance of the multiple layer device is about 5000 cd/m². On the other hand, the devices consisting of a spin-cast film containing a hole transport material, an electron transport material and CmCz showed a blue emission whose spectra are identical to the photoluminescent spectrum of CmCz in chloroform. Luminance of these devices is over 100 cd/m². © 1997 John Wiley & Sons, Ltd.     

Dynamic studies of angle-ply laminates including flexure–torsion coupling using laser holography

Laser holographic interferometry has been applied to experimentally investigate the effect of flexure–torsion coupling stiffnesses on the vibrational characteristics. Test specimens are two special types of angle-ply laminates, which enables us to examine the influence by a flexure–torsion coupling term alone. The theoretical analysis by a finite element method is also conducted to support the experimental results. It is found that the effect of coupling stiffnesses on the natural frequencies is comparatively small. On the other hand, the mode shapes are strongly affected by the coupling terms depending on both the fiber orientation and the aspect ratio of a cantilevered laminate.     

Synthesis and spectroscopic analysis of chromophoric lipids inducing pH-dependent liposome fusion

We design novel chromophoric amphiphiles 6a-c, which lead to pH-dependent membrane fusion of egg phosphatidylcholine (eggPC) liposome containing them. Lipids 6a-c comprise double alkyl chains, a single chain with a 2-nitrophenol group as a pH trigger, and dipeptide (Asp-Asp) between them. The pKa values of 2-nitrophenol groups of 6a-c in liposome are larger than that of hydrophilic compound 9 in an aqueous solution. Absorption spectra indicate that the fields around 2-nitrophenol of 6a-c situated in liposome membranes are more hydrophobic than that of 9 in an aqueous solution, whereas the environments around deprotonated 2-nitrophenolate of 6b and 6c are not so hydrophobic as that of 6a. This means that protonated 2-nitrophenol groups of 6a-c are embedded in bilayer membranes. Deprotonated 2-nitrophenol groups of 6b and 6c must be located in less hydrophobic circumstances, while that of 6a is still embedded in bilayer membranes because of its larger hydrophobicity. Absorption spectra and (1)H NMR spectra respectively suggest that protonated 2-nitrophenol groups of 6a and those of 6c might take face-to-face associations in bilayer membranes.