Nano‐emulsion use for the synthesis of polyaniline nano‐grains or nano‐fibers

We report that nano‐emulsions can be creatively used as a morphology selective synthesis method to prepare not only nano‐grains but also nano‐fibers with high selectivity. Synthesis of the two different morphological materials was demonstrated using polyaniline synthesis as a model case. Polyaniline nano‐grains were synthesized from aniline molecules in nano‐size aqueous droplets as polymerization sites whose droplets were generated by inverse water‐in‐oil nano‐emulsion use, and polyaniline nano‐fibers were synthesized from aniline in aqueous nano‐dimensional channels as polymerization sites whose channels were generated by direct oil‐in‐water nano‐emulsion use containing high population of oil droplets. Using the approaches, we successfully synthesized nano‐fibers of 60 nm diameter with 0.5 µm length and also nano‐grains having diameter of 60–80 nm. The two different polymerization sites of nano‐scale dimension were made by changing the ratio among surfactant, aqueous aniline/HCl solution, and oil, i.e. organic solvent. We found the nano‐fibers synthesized from the channels formed by the direct oil‐in‐water nano‐emulsion have higher bulk electrical conductivity than the nano‐grains which were synthesized from the droplets formed by the inverse water‐in‐oil emulsion. We also found that the emulsion use allows us to use a room temperature synthesis unlike conventional synthesis methods which require to use ice bath temperature. Physical properties of both nano‐fibers and nano‐grains synthesized were characterized by Fourier transform infrared (FTIR), UV–Vis spectra, scanning electron microscopy (SEM), and four probes conductivity measurement. Copyright © 2009 John Wiley & Sons, Ltd.     

Colorimetric signaling of Hg ions by a nitrobenzoxadiazole-appended cyclen-triester

A novel Hg²⁺-selective colorimetric sensor based on a cyclen–nitrobenzoxadiazole (NBD) conjugate was investigated. A cyclen derivative with three ester ligands was used as the binding site and the NBD moiety acted as the reporting chromogenic subunit. Interaction of 1 with Hg²⁺ ions resulted in a pronounced color change from pink to yellow, and fluorescence signaling was also possible. Selective colorimetric signaling of Hg²⁺ ions by NBD-functionalized cyclen with a detection limit of 1.5 × 10⁻⁶ M in aqueous environments was successfully achieved.     

Facile deposition of [60]fullerene and carbon nanotubes on ITO electrode by electrochemical oxidative polymerization of ethylenedioxythiophene

It was found that [60]fullerene encapsulated in p-sulfonatocalix[8]arene and single-walled carbon nanotubes (SWNTs) solubilized by sodium dodecylsulfate can be readily deposited on the ITO electrode by electrochemical oxidative polymerization of ethylenedioxythiophene (EDOT) without chemical modification of these carbon clusters. The driving force for the deposition is an electrostatic interaction between the anionic complexes and the cationic charges of poly(EDOT) formed in the oxidative polymerization process. The surface morphology was thoroughly characterized by scanning electron micrograph: the [60]fullerene/poly(EDOT) film is covered by nano-particles with 20-100 nm diameters whereas the SWNTs/poly(EDOT) film is covered by nanorods with several microm length and ca. 100 nm diameter. The results indicate that the anionic complexes act as nuclei for the polymer growth in the oxidation polymerization. Interestingly, when these modified ITO electrodes were photoirradiated, the appearance of a photocurrent wave was observed. The action spectra showed that the photoexcited energy of [60]fullerene or SWNTs is efficiently collected by the electroconductive poly(EDOT) film and transferred to the ITO electrode.     

The immune-stimulating peptide WKYMVm has therapeutic effects against ulcerative colitis

In this study, we examined the therapeutic effects of an immune-stimulating peptide, WKYMVm, in ulcerative colitis. The administration of WKYMVm to dextran sodium sulfate (DSS)-treated mice reversed decreases in body weight, bleeding score and stool score in addition to reversing DSS-induced mucosa destruction and shortened colon. The WKYMVm-induced therapeutic effect against ulcerative colitis was strongly inhibited by a formyl peptide receptor (FPR) 2 antagonist, WRWWWW, indicating the crucial role of FPR2 in this effect. Mechanistically, WKYMVm effectively decreases intestinal permeability by stimulating colon epithelial cell proliferation. WKYMVm also strongly decreases interleukin-23 and transforming growth factor-β production in the colon of DSS-treated mice. We suggest that the potent immune-modulating peptide WKYMVm and its receptor FPR2 may be useful in the development of efficient therapeutic agents against chronic intestinal inflammatory diseases.     

Inexpensive d‐dimensional matchings

Suppose that independent U(0, 1) weights are assigned to the ${d\choose 2}n^{2}$ edges of the complete d‐partite graph with n vertices in each of the d maximal independent sets. Then the expected weight of the minimum‐weight perfect d‐dimensional matching is at least $\frac{3}{16}n^{1-(2/d)}$. We describe a randomized algorithm that finds a perfect d‐dimensional matching whose expected weight is at most 5d³n^1?(2/d)+d¹⁵ for all d≥3 and n≥1. © 2002 John Wiley & Sons, Inc. Random Struct. Alg., 20, 50–58, 2002     

Contrasting friction and diffusion in molecularly thin confined films

We study, using fluorescence correlation spectroscopy, translational diffusion in molecularly thin liquids confined within a surface forces apparatus. The diffusion coefficient decreases exponentially from the edges towards the center of the Hertzian contact and further suggests the presence of a small number of distinct diffusion processes. This holds alike a crystallizable fluid (OMCTS) and a glass-former (1,2-propane diol), both of which displayed static friction. We conclude that friction, the average of an ensemble of molecules, masked massively heterogeneous molecular mobility.     

Preparation and Characterization of Ceramic Hollow Microspheres for Heavy Metal Ion Removal in Wastewater

Ceramic hollow microspheres (CHMSs) were prepared to use as supports for the removal of heavy metal ions from industrial waste-water. A water extraction sol–gel technique was used to prepare porous CHMS by extracting water from an emulsion of LUDOX (silica colloid; SiO₂, Aldrich Co.) and 2-ethyl-1-hexanol. Experiments were conducted to control pore size, wall thickness, and separation yield by examining the ratio of precursors (LUDOX and 2-ethyl-1-hexanol), catalyst (NH₄OH), sintering temperature, surfactant (SPAN 80), extractant (n-butanol), stirring speed, and concentration of precursor (LUDOX). The results revealed that the optimum conditions were 20 ml of a 10 wt% solution of LUDOX, 10 ml of NH₄OH, a sintering temperature of 500°C, 0.4 ml of SPAN 80, 200 ml of n-butanol, and a stirring speed of 730 rpm/100 ml of 2-ethyl-1-hexanol. CHMSs were impregnated in Cyanex 272 and examined for their ability to remove heavy metal ions from a solution. Based on an experiment involving the removal of metal ions using CHMSs that were prepared under optimum conditions, Zn ion was removed at a level of 0.354 mmol/g at pH 4, which was about twice the adsorption capacity of CHMSs prepared by Wilcox (Mater. Res. Soc. Symp. Proc.346, 201 (1994)).