Phase-dependent heat current of granular Josephson junction for different geometries

We theoretically investigate the phase-dependent heat transport of a temperature-biased granular Josephson junction in the presence of a perpendicular magnetic field. We illustrate the influence of geometry of the junction on the thermal current. The use of granular Josephson junction rather than bulk one makes significant changes in the heat current behavior. The heat current diffraction pattern of the rectangular, circular and annular geometries with no trapped fluxons demonstrates similar to the current of s-wave superconducting junction. By increasing the number of trapped fluxon, the pattern of current behaves such as d-wave superconducting junction. The feasibility of using granular superconductors, with different geometries, controlled by the magnetic field provides an appropriate tool to obtain the desired result for a specific application.     

Cu(BDC) as a catalyst for rapid reduction of methyl orange: room temperature synthesis using recycled terephthalic acid

Terephthalic acid was recycled from waste PET bottles with a basic hydrolysis technique and characterized with UV and FTIR spectroscopy. Copper-based metal–organic framework Cu(BDC) was synthesized at room temperature without any additive; two different temperatures were chosen to activate the obtained material. Characterization studies were performed using XRD, N₂ physisorption, STEM and EDX. The obtained material was tested as a catalyst for the reduction of methyl orange with NaBH₄ in aqueous solutions. Thermal activation at 160 °C proved to be mandatory for catalytic activity; although higher temperature activation did not cause significant enhancement. Rapid dye removal was monitored by continuous photometry at λ _max. The results were quite satisfactory (about 85% removal in 5 min); even higher than the published results for precious metal (i.e., Au, Pt and Ag) nanoparticles. In an increased reaction scale, UV–visible spectra and mass spectrum were recorded to help elucidating the possible reaction mechanism. In addition, recycling experiment were performed in 100-ml scale without any kind of re-activation (washing or drying) to show the ability of Cu(BDC) as a stable catalyst for reductive dye removal (and probably similar reactions as well).     

Development of an optode membrane for high pH values

The development of an optical pH sensor for high pH values is described based on the immobilization of Aniline Blue on an optically transparent triacetylcellulose membrane. The membrane is useful for repetitive and reversible pH measurements in the pH range of 8.8-13. The relative standard deviation is about 1.6% and 2% for seven measurements of the maximum change at 579 nm from pH 9 to 10.8 and from pH 11.1 to 12.8, respectively. Other advantages of the sensor include rapid equilibration time, long term stability, reversibility, high sensitivity, freedom from interference of other cations and ease of fabrication.     

Zeolite/Fe3O4 as a new sorbent in magnetic solid‐phase extraction followed by gas chromatography for determining phthalates in aqueous samples

In the present study, for the first time, we successfully employed zeolite/Fe₃O₄ as a new magnetic nanoparticle sorbent in magnetic solid‐phase extraction for determining phthalates in aqueous samples. Gas chromatography with flame ionization detection was used to detect the target analytes as a powerful instrumental analysis. Affecting parameters in the extraction process, including the amount of adsorbent, adsorption and desorption time, and volume of desorption solvent, were optimized using a response surface methodology based on central composite design. Under the optimum conditions, the linear range for dibutyl phthalate and bis(2‐ethylhexyl phthalate) was varied in the interval of 10–1700 and 10–1200 μg/L, respectively. Limits of detection were 2.80 μg/L for dibutyl phthalate and 3.20 μg/L for bis(2‐ethylhexyl phthalate). The recovery value for the extraction of target analytes was between 97 and 111%. The repeatability and reproducibility of the new proposed method were obtained: 10–13% and 13–13.5%, respectively. The increased sensitivity in using the proposed method has been demonstrated. Compared with previous methods, the new proposed method is an accurate, rapid, and reliable sample‐pretreatment method.     

Silica‐supported terpyridine palladium(II) complex as an efficient and reusable catalyst for Heck and Suzuki cross‐coupling reactions

Silica‐supported terpyridine palladium(II) was prepared and used as an effective and recyclable catalyst in Mizoroki–Heck and Suzuki–Miyaura coupling reactions. The catalyst was very effective for the Mizoroki–Heck reaction of aryl halides with olefins and conversion was in most cases excellent. The catalyst showed good thermal stability (up to 230 °C) and could be recovered and reused for four reaction cycles. The Suzuki coupling of aryl iodides with aryl boronic acids in the presence of the catalyst was also investigated and the reaction proceeded with a short reaction time and excellent conversion. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis of palladium nanoparticles on organically modified silica: Application to design of a solid-state electrochemiluminescence sensor for highly sensitive determination of imipramine

Organically modified silica substrate containing amine and vinyl functional groups were used for reduction and stabilization of palladium nanoparticles. Uniform spherical nanoparticles of palladium with average diameter of 10 nm were formed on silica substrate by direct contact of the substrate with an aqueous solution of palladium precursor, without the addition of any chemical reducer. Moreover, a sensitive and selective solid state electrochemiluminescence sensor was fabricated for the determination of imipramine, based on Ru(bpy)₃²⁺-palladium nanoparticles doped carbon ionic liquid electrode. In this process, imipramine acts as a co-reactant for Ru(bpy)₃²⁺. It is believed that the enhancement of the electrochemiluminescence signal in the presence of palladium nanoparticles in the composite is due to palladium catalytic effect on electrochemical and also chemical process involved in formation of Ru(byp)₃²⁺*. In addition, the results confirmed that, the rigid composite electrode shows the characteristic of microelectrode arrays. The proposed method was applied to the determination of imipramine in tablets and urine samples. The electrochemiluminescence intensity showed good linearity with the imipramine concentration from 1–100 pM, with a detection limit of 0.1 pM.     

Voltammetric Determination of Hemoglobin Using a Pencil Lead Electrode

In this paper the electrochemical behavior of hemoglobin (Hb) immobilized on a pencil lead electrode (PLE) was investigated. Immobilization of Hb on the pencil lead electrode was performed by nonelectrochemical and electrochemical methods. In phosphate buffer solution with pH 7.0 Hb showed a pair of well‐defined and nearly reversible redox waves (the anodic and cathodic peak potentials are located at ?0.18 V and ?0.22 V, respectively). The dependence of the anodic peak potential (E_pa) on the pH of the buffer solution indicated that the conversion of Hb? Fe(III)/Hb? Fe(II) is a one‐electron‐transfer reaction process coupled with one‐proton‐transfer. In addition the effect of scan rate on peak currents and peak separation potential was investigated and electrochemical parameters such as α and k_s were calculated. In the second part of this work, the ability of the electrode for determination of Hb concentration was investigated. The results showed a linear dynamic range from 0.15 to 2 µM and a detection limit of 0.11 µM. The relative standard deviation is 4.1 % for 4 successive determinations of a 1 µM Hb solution.     

Construction of a carbon nanocomposite electrode based on amino acids functionalized gold nanoparticles for trace electrochemical detection of mercury

A simple, highly sensitive and selective carbon nanocomposite electrode has been developed for the electrochemical trace determination of mercury. This mercury nanocomposite sensor was designed by incorporation of thiolated amino acids capped AuNps into the carbon ionic liquid electrode (CILE) which provides remarkably improved sensitivity and selectivity for the electrochemical stripping assay of Hg(II). Mercury ions are expected to interact with amino acids through cooperative metal–ligand interaction to form a stable complex which provides a sensitive approach for electrochemical detection of Hg(II) in the presence of other metal ions. The detection limit was found to be 2.3 nM (S/N = 3) that is lower than the permitted value of Hg(II) reported by the Environmental Protection Agency (EPA) limit of Hg(II) for drinkable water. The proposed nanocomposite electrode exhibits good applicability for monitoring Hg(II) in tap and waste water.