Simultaneous determination of iodide and iodate in seawater by transient isotachophoresis-capillary zone electrophoresis with artificial seawater as the background electrolyte

We developed capillary zone electrophoresis with transient isotachophoresis (ITP) as an on-line concentration procedure for simultaneous determination of iodide and iodate in seawater. The effective mobility of iodide was decreased by addition of 20 mM cetyltrimethylammonium chloride to an artificial seawater background electrolyte so that transient ITP functioned for both iodide and iodate. Limits of detection for iodide and iodate were 4.0 and 5.0 microg/l (as iodine) at a signal-to-noise ratio of 3. Values of the relative standard deviation of peak area, peak height, and migration times for iodide and iodate were 2.9, 1.3, 1.0 and 2.3, 2.1, 1.0%, respectively. The proposed method was applied to simultaneous determination of iodide and iodate in seawater collected at a pond at our university.     

In situ STM study of potential-dependent height change of a tetrathiafulvalene derivative embedded in alkanethiol self-assembled monolayers on Au(111)

Electroactive tetrathiafulvalene thiol islands embedded in an n-alkanethiol SAM matrix were studied under potential control using in situ scanning tunneling microscopy. Unlike previously studied stochastic switching, the apparent height of the island could be intentionally controlled in the present system by choosing the appropriate potential and the island size. The dependence of the height change on the potential and the size is explained as structural change of the island induced by the charging effect of the electroactive moiety.     

Enantioselective inclusion of amide guests into a chiral N,N′-ditrityl amino amide host to compensate the loss of hydrogen bonds broken by installation of trityl groups

A new crystalline N,N′-ditrityl amino amide host included several amide guests in the host cavity to form inclusion crystals. Although the installation of trityl groups into (S)-2-aminopropanamide broke its inherent hydrogen bonds of amide groups, inclusion of guest amides compensated the loss of hydrogen bonds. X-ray crystallography showed that these inclusion cavities and host–guest interactions such as hydrogen bonds, van der Waals interaction, and CH?O interactions play important roles for highly enantioselective inclusion. The enantiomeric inclusion was 67% ee (S-form) for N-phenyl 2-methylbutanamide, 82% ee (S-form) for N-phenyl 2-chlorobutanamide, and 83% ee (S-form) for N-phenyl 2-bromobutanamide.     

CuX2-mediated [4+2] benzannulation as a new synthetic tool for stereoselective construction of haloaromatic compounds

The CuX₂-mediated reaction of enynal units, including ortho-alkynylbenzaldehydes, with alkynes gives a variety of haloaromatic compounds stereoselectively in good to high yields. 2,2′-Binaphthyl skeletons are also readily prepared by the reaction of ortho-alkynylbenzaldehydes and diynes. The method was applied to the synthesis of poly-substituted tetracene derivatives.     

Possibility of the existence of blow‐up solutions to quasilinear degenerate Keller–Segel systems of parabolic–parabolic type

This paper deals with the quasilinear ‘degenerate’ Keller–Segel system of parabolic–parabolic type under the super‐critical condition. In the ‘non‐degenerate’ case, Winkler (Math. Methods Appl. Sci. 2010; 33:12–24) constructed the initial data such that the solution blows up in either finite or infinite time. However, the blow‐up under the super‐critical condition is left as an open question in the ‘degenerate’ case. In this paper, we try to give an answer to the question under assuming the existence of local solutions. Copyright © 2012 John Wiley & Sons, Ltd.