Highly sensitive optical sensor system for blood leakage detection

A highly sensitive method for the detection of blood leakage has been developed, and a practical sensor system for blood concentration measurement has been constructed. The present method is based on the attenuation of laser light by blood cells. The effects of the fluctuations of the incident laser light power are eliminated by normalizing the attenuated light intensity by the incident light intensity. A part of the incident laser light is reflected by a beam splitter mounted at the entrance of the test cell, of which the power is measured to provide base data for normalization. The optical path is extended to enhance sensitivity by using a pair of side mirrors. This multi-reflection method is very effective to increase sensitivity; the maximum sensitivity obtained for blood concentration is about 4 X 10^-6 by volume, which is significantly higher than that of the conventional sensors.     

Mechanism of soft solution processing formation of alkaline earth metal tungstates: an electrochemical and in situ AFM study

The mechanism of alkaline earth metal tungstate formation during soft solution processing was studied by cyclic voltammetry, electrochemical impedance spectroscopy and by direct in situ observation of the surface changes using atomic force microscopy. The electrochemical oxidation of W to WO₃ was followed by dissolution of WO₃ and, with some delay, by precipitation of tungstates at the metal surface. The same Tafel slopes observed in Li⁺, Ba²⁺, Sr²⁺ and Ca²⁺ containing solutions indicate that the course of the oxidation process is independent of the cation present in solution. The observed differences in the current-voltage curves outside the Tafel region are accounted for by the different film-forming tendencies of the various alkaline earth metal cations. The growth of tungstate layers at the W substrate decreases the electrochemically active area and limits the production of WO₄ ^2– at later stages of deposition. At low potentials (E<0.2 V) the oxidation of W is the rate-controlling step. At higher potentials, however, the dissolution process slows down due to a relative decrease of the pH in the electrode vicinity and dissolution becomes the rate-limiting step. Electronic Publication     

Temperature-disturbance free magnetic field sensor based on double fiber optic polarimetry

A double fiber-optic Mach-Zehnder interferometer for sensing magnetic fields is devised using two polarization maintaining single-mode fibers. This sensor achieves not only highly sensitive performance but also excellent immunity from temperature disturbance. The sensitivity attains 243 deg/mT (mT=10^-3N/A) for the sensing part of the 5 cm long fiber.     

Physicochemical Properties of Large-Ring Cyclodextrins (CD 18 ∼CD 21

Cyclomaltooctadecaose(CD₁₈),cyclomaltononadecaose(CD₁₉),cyclomaltoeicosaose(CD₂₀) andcyclomaltoheneicosaose(CD₂₁) are cyclic oligosaccharides composed of 18, 19, 20 and 21 D-glucose units, respectively. This report describes the physicochemical properties of CD₁₈, CD₁₉, CD₂₀ and CD₂₁ in terms of aqueous solubility, surface tension, optical rotation and acid-catalyzed hydrolysis.     

Quantum phase transitions of spin chiral nanotubes

Recently many interesting magnetic nanostructures have been fabricated and much attention is arising on the rich magnetic properties that originate in the quantum effects eminent in the nanoscale world. One of the peculiar aspects of the quantum effects is the spin excitation gap. In the spin-1/2 low-dimensional systems, the spin gap often appears when the lattice dimerization or the frustration in the spin–spin interaction are introduced. In the present study, we investigate the ground-state property of the spin-1/2 antiferromagnetic spin chiral nanotubes with the spatial modulation in the spin–spin interaction. The ground-state phase diagrams of them are determined by observing the behavior of the expectation value of the Lieb–Schultz–Mattis slow-twist operator calculated by the quantum Monte Carlo method with the continuous-time loop algorithm. We discuss the relation between the characteristic of the topology of the phase diagram and the chiral vector of the nanotubes.     

Photohaptenic Properties of Fluoroquinolones

Abstract— Although quinolone antibacterial agents have both phototoxicity and photoallergenicity, the latter's potency has been poorly investigated compared with the former's. Some of the photoallergic chemicals serve as photohap-tens, which lead to T-cell-mediated immune reactions after photobinding to protein by UVA radiation. We examined the photohaptenic potential of fluoroquinolones, including lomefloxacin (LFLX), ciplofloxacin, norfloxacin, ofloxacin, levofloxacin, fleroxacin, enoxacin and spar-floxacin (SPFX). The absorption spectra of the quinolo-nes were altered by UVA irradiation, with an exception of SPFX that seems to be photostable toward UVA. Bovine serum albumin and murine epidermal cells were coupled with these fluoroquinolones other than SPFX by exposure to UVA. Subcutaneous inoculation of fluoro-quinolone-photomodified epidermal cells induced and elicited a delayed-type hypersensitivity reaction in mice. However, epidermal cells incubated with LFLX without UVA exposure also induced and elicited a significant hypersensitivity reaction to a lesser degree than LFLX-pho-tomodified epidermal cells. Furthermore, there was cross-reactivity between LFLX-photomodified epidermal cells and simply LFLX-incubated cells. This suggests that cells can be weakly modified with LFLX even in the dark and that UVA irradiation promotes this modification. Our study demonstrated that fluoroquinolones have photohaptenic properties to which their photoallergenicity is probably ascribed.     

Parametric excitation of the drift wave by a modulated ion beam

Parametric excitation of the drift wave is observed by an ion beam modulated near the lower-hybrid frequency. An rf field parallel to the magnetic field is found to play an important role in the excitation of the instability. Substantial increase of the ion and electron temperatures is observed.