Preparation of poly(3,4-ethylenedioxythiophene) nanofibers modified pencil graphite electrode and investigation of over-oxidation conditions for the selective and sensitive determination of uric acid in body fluids

In this study, we have performed the preparation of over-oxidized poly(3,4-ethylenedioxythiophene) nanofibers modified pencil graphite electrode (Ox-PEDOT-nf/PGE) to develop a selective and sensitive voltammetric uric acid (UA) sensor. It was noted that the over-oxidation potential and time had a prominent effect on the UA response of the Ox-PEDOT-nf/PGE. Characterizations of PEDOT-nf/PGE and Ox-PEDOT-nf/PGE have been performed by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The highest voltammetric response of UA was obtained at pH 2.0. A linear relationship between the concentration of UA and oxidation peak currents was observed in the concentration range of 0.01–20.0 μM. The detection limit (1.3 nM according to S/N = 3) and reproducibility (RSD: 4.6 % for N:10) have also been determined. The effects of different substances on the determination of UA have been investigated. A very high peak separation value of 423 mV was obtained between UA and ascorbic acid which is the major interfering substance for UA. The use of Ox-PEDOT-nf/PGE has been successfully tested in the determination of UA in human blood serum and urine samples for the first time in the literature.     

Selective recognition of americium by peptide-based reagents

The separation of lanthanides from minor actinides such as americium and curium is an important step during the recycling process in the treatment of nuclear waste. However, the similar chemistry and ionic size of lanthanide and actinide ions make the separation challenging. Here, we report that a peptide-based reagent can selectively bind trivalent actinides over trivalent lanthanides by means of introducing soft-donor atoms into a peptide known as a lanthanide-binding tag (LBT). Fluorescence spectroscopy has been used to measure the dissociation constant of each metal/peptide complex. A 10-fold selectivity was obtained for Am(3+) over the similarly sized lanthanide cation, Nd(3+), when the asparagine on the fifth position of a LBT was mutated to a cysteine and further functionalized by a pyridine moiety.     

Synthesis, characterization, and electrochemical and electrical properties of novel mono and ball-type metallophthalocyanines with four 9,9-bis(4-hydroxyphenyl)fluorene

The new mono-nuclear 4-5 and ball-type homo-dinuclear 6 phthalocyanines have been synthesized from the corresponding phthalodinitrile derivative 3. The synthesized compounds have been characterized by elemental analysis, UV-vis, IR,(1)H-NMR and MALDI-TOF-mass spectroscopies. The redox behaviours of the complexes were identified by cyclic voltammetry and square wave voltammetry. The temperature dependence of the electronic properties of compounds and adsorption of SO(2) on thin film of 6 were investigated by conductivity measurements using an interdigital transducer structure on glass substrate. Dc conductivity, measured between 300-475 K, is thermally activated with the activation energy ranging between 0.67 and 0.90 eV. The ac conductivity is found to vary with frequency, ω, as ω(s) in which the frequency exponent s decreases with temperature suggesting a hopping conduction mechanism for all compounds. The SO(2) sensing result showed that the spin coated film of 6 exhibits very good SO(2) sensing properties, fast response and recovery rate, high sensitivity and good repeatability.     

Chemically modified biolubricant basestocks from epoxidized oleic acid: Improved low temperature properties and oxidative stability

Synthetic biolubricant basestocks with improved low temperature and oxidative stability were prepared by chemical modification of epoxidized oleic acid (EOA). Preparation, characterization and physico-chemical properties of mono, di and triester derivatives of 9,10-dihydroxyoctadecanoic acid after the epoxidation of oleic acid, opening of the formed oxirane ring in suitable medium, esterification of carboxylic acid hydroxyl group and acetylation of free hydroxyl group is discussed in this paper. Removal of the double bond from fatty acid acyl group, increase of the molar weight and change of molecular structure resulted in the increase of viscosity index and oxidation stability of synthetic esters.     

Facile and mild solution synthesis of Cu2O nanowires and nanotubes driven by screw dislocations

We report a green synthesis of Cu(2)O nanowires and nanotubes in aqueous solution by reducing Cu(2+) to Cu(+) with glucose or fructose via Fehling's reaction. The screw dislocation-driven growth of Cu(2)O nanowires and nanotubes is confirmed by imaging the dislocation contrast, the Eshelby twist associated with dislocations and the spontaneously formed hollow nanotubes.     

Analytical solutions of a class of inverse coefficient problems

This paper is devoted to some class of inverse coefficient problems. By using a well-known transformation, the inverse problem is transformed to a new problem without the unknown time dependent coefficient. Therefore, the new inverse problem can be solved easily. To show the efficiency of the present method, some examples are presented.     

Real-time optical imaging and tracking of micron-sized particles

We report real-time imaging and dynamics monitoring of micrometer predefined and random sized particles by time-space-wavelength mapping technology using a single-detector. Experimentally, we demonstrate real-time line imaging of a 5 μm polystyrene microsphere, glass powder particles and patterns such as fingerprints with up to 5 μm resolution at 1 line/50 ns capture rate. By using the same setup, real-time displacement tracking of micrometer-size glass particles with 50 ns temporal resolution and up to 5 μm spatial resolution is achieved. We also show that existing correlation spectroscopy algorithms can be adopted to extract dynamic information in a complex environment.     

Tetrakis‐phthalocyanines bearing electron‐withdrawing fluoro functionality: Synthesis,spectroscopy, and electrochemistry

In this study, 2,9,16,23‐tetrakis‐4′‐(2,3,5,6‐tetrafluoro)‐phenoxy‐phthalocyaninatometalfree and metal(II) complexes, (H₂PcBzF₁₆, ZnPcOBzF₁₆, CuPcOBzF₁₆, and CoPcOBzF₁₆) (Bz: Benzene) (2H, Zn, Cu, and Co), have been prepared directly from the corresponding 4′‐(2,3,5,6‐fluorophenylthio)‐phthalonitrile compounds in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) in high boiling quinoline solvent. Tetrafluoro atoms on 2,3,5,6‐position of benzene at the peripheral sites of phthalocyanines (Pcs) give rise interesting solubility to tetrakismetallophthalocyanines. Although all complexes were soluble in DCM, CHCl₃, THF, DMF, and DMSO with increasing order, complexes synthesized, particularly H₂PcBzF₁₆, CuPcOBzF₁₆, have very limited solubility in DMF and DMSO. The complexes have been characterized by elemental analysis, FTIR, ¹H NMR, UV–vis, and MALDI–TOF mass spectral data. The cyclic voltammetry and differential pulsed voltammetry of the complexes show that while H₂PcBzF₁₆, CuPcOBzF₁₆, and ZnPcOBzF₁₆ give ligand‐based reduction and oxidation processes, CoPcOBzF₁₆ gives both ligand and metal‐based redox processes, in harmony with the common metallophthalocyanine complexes. Redox processes due to both aggregated and disaggregated species were simultaneously observed during the first reduction process. The nature of the metal‐based redox processes was confirmed using spectroelectrochemical measurements. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:262–271, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20545     

Synthesis and spectroscopic studies of novel transition metal complexes with schiff base synthesized from 1,4-bis-(<Emphasis Type="Italic">o</Emphasis>-aminophenoxy)butane and salicyldehyde

The new Co(II), Cu(II), Ni(II) and Zn(II) complexes of potentially N₂O₂ Schiff base ligand [N,N’-bis(salicyldehydene)-1,4-bis-(o-aminophenoxy)butane] (H₂L) prepared from 1,4-bis-(o-aminophenoxy)butane and salicyldehyde in DMF. Microanalytical data, elemental analysis, magnetic measurements, ^lH NMR, ¹³C NMR, UV-visible and IR spectra as well as conductance measurements were used to confirm the structures. In all complexes, H₂L behaves as a tetradentate. The article is published in the original.