Scattering of traveling spots in dissipative systems

One of the fundamental questions for self-organization in pattern formation is how spatial periodic structure is spontaneously formed starting from a localized fluctuation. It is known in dissipative systems that splitting dynamics is one of the driving forces to create many particle-like patterns from a single seed. On the way to final state there occur many collisions among them and its scattering manner is crucial to predict whether periodic structure is realized or not. We focus on the colliding dynamics of traveling spots arising in a three-component system and study how the transition of scattering dynamics is brought about. It has been clarified that hidden unstable patterns called "scattors" and their stable and unstable manifolds direct the traffic flow of orbits before and after collisions. The collision process in general can be decomposed into several steps and each step is controlled by such a scattor, in other words, a network among scattors forms the backbone for scattering dynamics. A variety of input-output relations comes from the complexity of the network as well as high Morse indices of the scattor. The change of transition manners is caused by the switching of the network from one structure to another, and such a change is caused by the singularities of scattors. We illustrate a typical example of the change of transition caused by the destabilization of the scattor. A new instability of the scattor brings a new destination for the orbit resulting in a new input-output relation, for instance, Hopf instability for the scattor of peanut type brings an annihilation.     

Colorimetric chemosensor for Fe<Superscript>2+</Superscript> and Fe<Superscript>3+</Superscript> based on a ternary mixture of an anionic dye,a cationic polyelectrolyte,and a metal chelator in aqueous solution

A new colorimetric chemosensor based on a simple ternary mixture of an anionic dye, pyrogallol red (PR), a cationic polyelectrolyte, poly(diallyldimethylammonium chloride) (PDADMAC), and a metal chelator, N-(2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA) for the colorimetric detection of Fe²⁺ and Fe³⁺ has been developed in an aqueous solution buffered at pH 5. Upon addition of Fe²⁺ or Fe³⁺ to the mixture, the absorption spectra showed a bathochromic shift; correspondingly, the solution color changed from red to blue, whereas other metal ions basically resulted in insignificant spectral and color changes. From the competitive experiments, no obvious interferences for the colorimetric detection of Fe²⁺ and Fe³⁺ were observed in the presence other metal ions. The results indicated that the mixture could be used as a potential Fe²⁺ and Fe³⁺ colorimetric and naked eye chemosensor in aqueous media. This research demonstrates that the ternary ensemble consisted of an organic dye, an oppositely charged polyelectrolyte, and a metal chelator is a versatile and convenient tool for the facile preparation of a novel chemosensor system.     

Complete assignment of bilberry (Vaccinium myrtillus L.) anthocyanins separated by capillary zone electrophoresis

Capillary zone electrophoresis (CZE) mobilities of fifteen anthocyanins in bilberry extract were completely characterized. Four minor anthocyanins in bilberry extract (malvidin 3-O-alpha-L-arabinopyranoside (Mv 3-ara), peonidin 3-O-beta-D-galactopyranoside (Pn 3-gal), peonidin 3-O-alpha-L-arabinopyranoside (Pn 3-ara), and petunidin 3-O-alpha-L-arabinopyranoside (Pt 3-ara)) that remained unidentified in our previous CZE study were isolated from the bilberry extract, and the chemical structures were assigned by NMR and MS. Their CZE mobilities were then precisely examined together with those of other major anthocyanins in the extract. When the CZE mobilities of the fifteen anthocyanins assigned here were plotted against their molecular weight/numbers of free phenolic group, it was found that separation of anthocyanins by CZE is primarily determined by the type of conjugated sugar present, and secondly by the aglycon structure.     

Synthesis and application of new chiral bidentate phosphine, 2,7-di-tert-butyl-9,9-dimethyl-4,5-bis(methylphenylphosphino)xanthene

New optically active bidentate phosphines, (S,S)- and (R,R)-2,7-di-tert-butyl-9,9-dimethyl-4,5-bis(methylphenylphosphino)xanthenes ((S,S)-1 and (R,R)-1), were prepared through resolution of the corresponding phosphine oxides using (R,R)-(−)-dibenzoyl-tartaric acid and a preliminary experiment on asymmetric synthesis using an allyl substrate proved the utility of the new bidentate phosphines.     

Determination of traces of uranium and thorium in (Ba, Sr) TiO3 ferroelectrics by inductively coupled plasma mass spectrometry

 Traces of uranium and thorium in barium(II), strontium(II) titanate ((Ba, Sr)TiO₃) ferroelectric materials were determined by inductively coupled plasma mass spectrometry (ICP-MS). Samples were completely dissolved by a mixture of 1.4% H₂O₂ and 1.0 mol⋅l^-1 HNO₃. For a complete separation of the analytes from the matrix elements, a two step separation technique involving leaching and anion-exchange was applied. By the leaching step with HNO₃ more than 90% of the matrix can be removed whereas the analytes completely remained in the solution. The anion-exchange step was carried out on a BIO⋅RAD AG1-X8 column with a mixture of 1.0 mol⋅l^-1 HF and 0.5 mol⋅l^-1 HNO₃ as eluent. The content of uranium and thorium was subsequently measured by ICP-MS. The detection limits (D.L.) obtained were 0.043 ng g^-1 and 0.035 ng g^-1 for U and Th, respectively. The reproducibility was satisfactory with a relative standard deviation of less than 3% (at the 1 ng g^-1 level, n=5). The matrix concentrations in the final solution were reduced to the sub-μg ml^-1 level which is in the range of the detection limits of USN-ICP-AES (ultrasonic nebulization-ICP-atomic emission spectroscopy). The method was successfully applied to the determination of uranium and thorium in three synthetic (Ba, Sr)TiO₃ samples spiked with the analytes at levels of 1, 5 and 10 ng g^-1 and three (Ba, Sr)TiO₃ ferroelectric samples containing sub-ng g^-1 levels of the analytes. Received: 26 February 1996/Revised: 28 May 1996/Accepted: 5 June 1996     

Synthesis and properties of new aromatic poly‐(ether benzoxazole)s from 2,2′‐bis(4‐amino‐3‐hydroxyphenoxy)biphenyl and aromatic dicarboxylic acid chlorides

A new bis(o‐aminophenol) with a crank and twisted noncoplanar structure and ether linkages, 2,2′‐bis(4‐amino‐3‐hydroxyphenoxy)biphenyl, was synthesized by the reaction of 2‐benzyloxy‐4‐fluoronitrobenzene with biphenyl‐2,2′‐diol, followed by reduction. Biphenyl‐2,2′‐diyl‐containing aromatic poly(ether benzoxazole)s with inherent viscosities of 0.52–1.01 dL/g were obtained by a conventional two‐step procedure involving the polycondensation of the bis(o‐aminophenol) monomer with various aromatic dicarboxylic acid chlorides, yielding precursor poly(ether o‐hydroxyamide)s, and subsequent thermal cyclodehydration. These new aromatic poly(ether benzoxazole)s were soluble in methanesulfonic acid, and some of them dissolved in m‐cresol. The aromatic poly(ether benzoxazole)s had glass‐transition temperatures of 190–251 °C and were stable up to 380 °C in nitrogen, with 10% weight losses being recorded above 520 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2656–2662, 2002     

Observation of an optical vortex beam from a helical undulator in the XUV region

The observation of an optical vortex beam at 60 nm wavelength, produced as the second‐harmonic radiation from a helical undulator, is reported. The helical wavefront of the optical vortex beam was verified by measuring the interference pattern between the vortex beam from a helical undulator and a normal beam from another undulator. Although the interference patterns were slightly blurred owing to the relatively large electron beam emittance, it was possible to observe the interference features thanks to the helical wavefront of the vortex beam. The experimental results were well reproduced by simulation.     

SPring‐8 BL36XU: Synchrotron Radiation X‐Ray‐Based Multi‐Analytical Beamline for Polymer Electrolyte Fuel Cells under Operating Conditions

We designed and constructed a beamline BL36XU at the 8 GeV synchrotron radiation facility SPring‐8 to provide information required for the development of next‐generation polymer electrolyte fuel cells (PEFCs) by clarifying the dynamic aspects of structures and electronic states of cathode catalysts under PEFC operating conditions and in the deterioration processes by accelerated durability test protcols. To investigate the mechanism and degradation process for the cathode electrocatalysis in practical PEFCs, we developed advanced time‐ and spatially‐resolved in‐situ/operando X‐ray absorption fine structure measurement systems and complementary analytical systems (X‐ray emission spectroscopy (XES), X‐ray diffraction (XRD), X‐ray computer tomography (CT) and hard X‐ray photoelectron spectroscopy (HAXPES)) and combined them to develop multi‐analytical systems at BL36XU. Multi‐analytical systems are very powerful for observing spatial‐temporal features of the transient processes occurring in complex systems such as PEFCs. This account describes the design, performance, and research results of the BL36XU and multi‐analytical in‐situ/operando systems.     

Enantio and diastereoselective total synthesis of all four stereoisomers of germicidin N

Abstract

Germicidin N (3-ethyl-4-hydroxy-6-[(1S, 2?R)?2-hydroxy-1-methylpropyl]-2H-pyran-2-one, 1), a new α-pyrone from the extracts of a Streptomyces sp. derived from marine algae, has been synthesized for the first time as four possible diastereomers from chiral β-hydroxyester ((S)?6 and (R)?9) through the stereoselective alkylation, Claisen condensation followed by cyclization in a straightforward manner.