Use of floating electrodes in transient isotachophoresis to increase the sensitivity of detection

We report a protocol for on-chip electrophoretic sample loading and sample component separation in which each operation requires simultaneous control of the potential of only two electrodes: during the sample-loading phase, the potentials at the ends of the separation channel are electrically floating; during electrophoresis of the sample mixture down the separation channel, the potentials at the ends of the sample-introduction channel are floating. This method, which we call "floating-stacking," avoids the dispersion/distortion of the sample plug that is commonly associated with simultaneous electrical control of only two electrodes in a crossed-channel or offset-double-tee injection system. Further, when this floating loading/separation is done in the presence of back-transient-isotachophoresis, sample loss from the plug of material being injected is minimal and a significant concentration increase--up to 13x--of the sample components in the separated bands occurs relative to the commonly used "pinch-and-pull-back" technique (which requires simultaneous electrical control of four electrodes).     

Yttrium polyoxometalates. Synthesis and characterization of a carbonate-encapsulated sandwich-type complex

Reaction of A-alpha-PW(9)O(34)(9)(-) with YCl(3) in an aqueous Na(2)CO(3) solution produces a dianion-encapsulated A-type sandwich polyoxometalate, (YOH(2))(3)(CO(3))(A-alpha-PW(9)O(34))(2)(11)(-). The X-ray structure of this complex reveals that three Y(III) ions are sandwiched between two A-alpha-PW(9)O(34)(9)(-) moieties and that a carbonate dianion is encapsulated in the same plane as the three Y(III) atoms. The oxygen atoms of the CO(3)(2)(-) are sitting at the midpoints of the sides of the triangle formed by the three Y(III) ions. (31)P and (13)C NMR studies confirm that this complex is significantly more stable than the analogous A-type sandwich polyoxometalates containing divalent metals.     

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PH-Bestimmungsmethoden

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Polymerizable cationic iridium(III) complexes exhibiting color tunable light emission and their corresponding conducting metallopolymers

Cyclometalated iridium(III) complexes have been synthesized for use in a variety of photophysical applications, including polymer light emitting diodes (PLEDs). A series of new complexes with one electrochemically polymerizable ligand and two phenylpyridine(ppy)-based ligands have been prepared: [Ir(ppy)₂L][PF₆](1), [Ir(F-mppy)₂L][PF₆](2), and [Ir(Br-mppy)₂L][PF₆](3), where L = 3,8-bis(2,2′-bithien-5-yl)-1,10-phenanthroline. The ancillary ppy ligands can be easily varied synthetically to tune emission color of the monomer from blue–green to red. The solid state structure of complex 1 has been obtained by single crystal X-ray crystallography. Conducting polymer materials have been prepared by electropolymerization of monomers and were characterized through XPS analysis and spectroscopic studies.     

Chemical-genetic screen identifies riluzole as an enhancer of Wnt/β-catenin signaling in melanoma

To identify new protein and pharmacological regulators of Wnt/β-catenin signaling, we used a cell-based reporter assay to screen a collection of 1857 human-experienced compounds for their ability to enhance activation of the β-catenin reporter by a low concentration of WNT3A. This identified 44 unique compounds, including the FDA-approved drug riluzole, which is presently in clinical trials for treating melanoma. We found that treating melanoma cells with riluzole in?vitro enhances the ability of WNT3A to regulate gene expression, to promote pigmentation, and to decrease cell proliferation. Furthermore riluzole, like WNT3A, decreases metastases in a mouse melanoma model. Interestingly, siRNAs targeting the metabotropic glutamate receptor, GRM1, a reported indirect target of riluzole, enhance β-catenin signaling. The unexpected regulation of β-catenin signaling by both riluzole and GRM1 has implications for the future uses of this drug.     

In situ measurements of the spectral emittance of coal ash deposits

The spectral emittance of deposits left by bituminous and sub-bituminous coals under oxidizing conditions have been measured in situ. Pulverized coal is injected into a down-fired entrained-flow reactor. Ash accumulates on a probe in the reactor effluent and radiation emitted by the ash layer is recorded using a Fourier transform infrared (FTIR) spectrometer. Values for the spectral emissive power emitted by the ash and the surface temperature of the ash are extracted from these data. These results are then used to calculate the spectral emittance of the deposit. The spectral emittances of ash deposits formed by burning Illinois #6 (bituminous) coal and Powder River Basin (sub-bituminous) coal were measured between 3000 and 500 wavenumbers. The spectral emittance of the deposit left by the bituminous coal has a constant value of approximately 0.46 between 3000 and 2400 wavenumbers. Between 2200 and 1200 wavenumbers, the spectral emittance of the deposit increases from approximately 0.47 to approximately 0.61. Between 1200 and 500 wavenumbers, the spectral emittance is relatively constant at 0.61. The spectral emittance of the deposit left by the sub-bituminous coal is also relatively constant between 3000 and 2400 wavenumbers at a value of 0.29. Between 2200 and 500 wavenumbers, the spectral emittance of deposits from the sub-bituminous coal increases from approximately 0.29 to 0.55. Differences between these spectral emittance measurements and those measured ex situ illustrate the importance of making in situ measurements. Band emittances were calculated using the measured spectral emittances, and band emittances of the deposits are reported as functions of temperature.     

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Bestimmung kleiner Mengen Zink in organischen Substanzen, insbesondere in Aepfelschnitten

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