Optical current transducers using flint glass fiber as the faraday sensor element

This paper describes development of the optical current transducers using flint glass fiber as the Faraday effect sensing element. Excellent polarization properties of the fiber with low birefringence are described, and the design and test data of a current transducer using the fiber manufactured for use in electric power facilities are reviewed. Experimental results on flexible characteristics of a scheme with round trip light transmission in the fiber is also reported.     

Numerical analysis of finite amplitude motion of waves and a moored floating body under severe storm conditions

The motion of a moored floating body under the action of wave forces, which is influenced by fluid forces, shape of the floating body and mooring forces, should be analysed as a complex coupled motion system. Especially under severe storm conditions or resonant motion of the floating body it is necessary to consider finite amplitude motions of the waves, the floating body and the mooring lines as well as non-linear interactions of these finite amplitude motions. The problem of a floating body has been studied on the basis of linear wave theory by many researchers. However, the finite amplitude motion under a correlated motion system has rarely been taken into account. This paper presents a numerical method for calculating the finite amplitude motion when a floating body is moored by non-linear mooring lines such as chains and cables under severe storm conditions.     

Synthesis and properties of furo[4,3,2-de][1]benzopyran

A new heterocycle, furo[4,3,2-de][1]benzopyran ( 2 ), was synthesized. A key step in the sequence was the allylic bromination of 3,4-dihydrofuro[4,3,2-de][1]benzopyran ( 8 ) to give 3-bromo-3,4-dihydrofuro[4,3,2-de][1]-benzopyran ( 10 ) using N-bromosuccinimide under irradiation and high dilution conditions. Bromide 10 was dealt with 1,8-diazabicyclo[5.4.0]undec-7-ene to afford compound 2 . Several reactions of 2 were examined. Protonation of 2 in trifluoroacetic acid occurred at the 2-position to form a pyrylium ion 12 . Catalytic hydrogenation of 2 with palladium on charcoal proceeded smoothly to give 8 . Reduction of 2 by sodium and ethanol afforded 3-ethyl-4-hydroxybenzofuran ( 14 ). Electrophilic substitutions of 2 such as formylation, acetylation, and bromination, occurred easily at the 2-position. The above results show that compound 2 has both properties of benzofuran and 4-methylenepyran.     

Microlocal study of topological Radon transforms and real projective duality

Various topological properties of projective duality between real projective varieties and their duals are obtained by making use of the microlocal theory of (subanalytically) constructible sheaves developed by Kashiwara [M. Kashiwara, Index theorem for constructible sheaves, Astérisque 130 (1985) 193-209] and Kashiwara-Schapira [M. Kashiwara, P. Schapira, Sheaves on Manifolds, Grundlehren Math. Wiss., vol. 292, Springer, Berlin-Heidelberg-New York, 1990]. In particular, we prove in the real setting some results similar to the ones proved by Ernström in the complex case [L. Ernström, Topological Radon transforms and the local Euler obstruction, Duke Math. J. 76 (1994) 1-21]. For this purpose, we describe the characteristic cycles of topological Radon transforms of constructible functions in terms of curvatures of strata in real projective spaces.     

Pressure and temperature effects on the excess deuteron and proton conductance

The limiting molar conductances ° of deuterium chloride DCl in D₂O were determined as a function of pressure and temperature in order to examine the proton-jump mechanism in detail. The excess deuteron conductances °_E(D ⁺), as estimated by the equation [°_E(D ⁺) = °(DCl/D ₂ O) – °(KCl/D ₂ O)], increases with an increase in the pressure and temperature as well as the excess proton conductance [°_E(H ⁺) = °(HCl/H ₂ O) – °(KCl/H ₂ O)]. The isotope effect on the excess conductances, however, depends on the pressure and temperature contrary to the model proposed by Conway et al.: °_E(H ⁺)/°_E(D ⁺) decreases with increasing pressure and temperature. The magnitude of the decrease with pressure becomes more prominent at lower temperature. These results are discussed in terms of the pre-rotation of adjacent water molecules, the bending of hydrogen bonds with pressure, and the difference in strength of hydrogen bonds between D₂O and H₂O.     

Gas-stirred solvent extraction with propylene carbonate for separation and direct polarographic determination of thallium (III)

Gas-stirred propylene carbonate (PC) extraction can be performed by bubbling nitrogen without loss of volume. This extraction technique has proved to be highly useful for the separation and subsequent direct polarographic estimation of Tl(III) in the recovered PC phase. Tl(III) can be determined by differential-pulse polarography over the concentration range of 0.4 10 g ml^–1 without any interferences due to most metal ions such as Pb(II), Bi(III), Cu(II), Sb(III) and As(III). This proposed technique would be possible to use as a simple extraction step prior to the final estimation by instrumental method of analysis such as atomic absorption spectrometry or spectrophtometry.     

Enhancement of electronic excitation energy transfer in the colloidal crystals of colloidal silica suspensions doped with fluorescent dyes

The efficiency of electronic excitation energy transfer from photo-excited rhodamine 110 (Rh110, energy donor) to rhodamine B (RhB, energy acceptor) in an exhaustively deionized colloidal silica suspension has been studied. This colloidal suspension shows Bragg reflection due to the formation of colloidal crystals and the Bragg-peak wavelength is controllable by the volume fraction of the silica spheres. When the Bragg-peak wavelength matches with the fluorescence band of Rh110, a depletion was observed in the Rh110 fluorescence spectrum. This means the fluorescence of Rh110 is partially trapped due to the Bragg reflection inside the crystal lattice. In the coexistence of RhB, the enhancement of RhB fluorescence intensity was observed. These facts clearly indicate the trapped photon energy of Rh110 is efficiently transferred to RhB within the colloidal crystals. The quantitative measurements showed that the enhancement of the transfer efficiency is 20% (or slightly more) in the present experimental conditions.     

Electrode reaction of zinc ions at a dropping mercury electrode in ammonium sulphate solutions

The electrode reaction of Zn(II) at a DME in aqueous solutions of (NH₄)₂SO₄ has been studied by d.c. and square-wave polarography at 25.0±0.1°C. The electrochemical kinetic parameters for the reaction are determined. The appearance of the second wave in the square-wave polarogram has been attributed to the low values of the rate parameter and the transfer coefficient.     

Remarkably large positive and negative allosteric effects on ion recognition by the formation of a novel helical pseudocryptand

In supramolecular chemistry, a great deal of attention has focused on regulating guest binding via an external stimulus. To utilize the same effector for both highly guest-selective positive and negative allosteric effects, however, stricter and more precise regulation of the host structure is required. A novel allosteric host 1 binds Fe(II) to afford the pseudocryptand, 1.Fe(II), which bears a cavity that is surrounded by three polyether chains in a helical fashion. The binding selectivity of 1 (Na+ > K+ > Rb+ > Cs+) is the opposite of 1.Fe(II) (Cs+ > Rb+ > K+ > Na+). Single-ion transport through a liquid membrane shows ion selectivity similar to the equilibrium constants. To the best of our knowledge, this is the first example of an allosteric recognition system, in which the same effector, that is, Fe(II), exhibits both large positive and negative allosteric effects on equilibrium and dynamic recognition events. The X-ray analysis and 1H NMR examination indicate that the combination of the macrobicyclic effect and the intramolecular interchain interactions (CH-pi interaction and steric hindrance) finely controls the positive and negative allosteric effects, which depend on the size of the guest. The helical framework opens a new general method for constructing more sophisticated, controllable receptors for helical biomolecules, for example, DNA and proteins, and helical molecular devices such as a molecular coil or spring responding to a stimulus.