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Pollution of heavy metals in water can affect the health of humans and the environment; therefore, removal of heavy metal ions is getting the attention of scientists. To reduce the negative impact of heavy metals on human health and the environment, Cd2+ ions present in water were treated using hydroxyapatite (HAp) as adsorbent. The effects of contact time, initial Cd2+ concentration, solution pH, and adsorbent mass on the adsorption capacity and efficiency of HAp were investigated. Cd2+ uptake was quantitatively evaluated using Langmuir and Freundlich adsorption isotherms. The maximum monolayer adsorption capacity was 119 mg/g. The experimental adsorption data were analyzed using three kinetic models: Lagergren’s pseudo-first-order law, McKay and Ho’s pseudo-second-order law, and the intra-particle diffusion model. The results showed that the Cd2+ removal process follows the pseudo-second-order law.

A metal organic framework (MOF) material based on Cu-BTC, which is formed from Cu and benzene-1,3,5-tricarboxylic acid (H3BTC), with 1D and 3D structures was synthesized under potential control. Cu-BTC 3D was electrodeposited at an applied potential of 5 V using tetrabutylammonium tetrafluoroborate (TBATFB) as electrolyte during 10–60 min. Hydration showed that the phase structure of Cu-BTC 3D did not change after a short time of immersing in water and that the specific surface area increased from 48 m2/g to 371 m2/g. In contrast, with a long time of hydration (more than 4 h), Cu-BTC was destroyed and a dehydration process could not recover the Cu-BTC structure.

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Constant current chronopotentiometry is employed in conjunction with cyclic voltammetry and ac voltammetry to present in‐depth interfacial characterisations of the adsorption behaviour of a peptide affinity probe (Cys‐p53), of a thiolated hepta(ethylene glycol) (t‐OEG) and of mixed monolayers of these at mercury electrodes. The peptide sequence is derived from the interaction site of the protein p53 with the protein Mdm2. The adsorbed Cys‐p53 peptide is catalytically active towards the hydrogen evolution reaction, giving rise to very intense peaks in chronopotentiometry, whereas the oligo(ethylene glycol) is not. This difference enables one to monitor the presence of the peptide within mixed monolayers. It is shown that in the binary layers, the adsorption of t‐OEG is kinetically favoured while Cys‐p53 is thermodynamically more strongly adsorbed. [ABSTRACT FROM AUTHOR]

Pollution of heavy metals in water can affect the health of humans and the environment; therefore, removal of heavy metal ions is getting the attention of scientists. To reduce the negative impact of heavy metals on human health and the environment, Cd2+ ions present in water were treated using hydroxyapatite (HAp) as adsorbent. The effects of contact time, initial Cd2+ concentration, solution pH, and adsorbent mass on the adsorption capacity and efficiency of HAp were investigated. Cd2+ uptake was quantitatively evaluated using Langmuir and Freundlich adsorption isotherms. The maximum monolayer adsorption capacity was 119 mg/g. The experimental adsorption data were analyzed using three kinetic models: Lagergren's pseudo-first-order law, McKay and Ho's pseudo-second-order law, and the intra-particle diffusion model. The results showed that the Cd2+ removal process follows the pseudo-second-order law. [ABSTRACT FROM AUTHOR]

This study deals with the development of an original epi-fluorescence-based protocol to evaluate the anti-biofouling character of atmospheric pressure plasma-polymerized poly(ethylene glycol) samples. In this work, fluorescence microscopy is considered as an alternative to XPS for the evaluation of protein adsorption. The full set of samples is tested before and after bovine serum albumin-fluorescein isothiocyanate treatment. It appears that their anti-biofouling property, expressed by the variation of fluorescence intensity, is reduced when the power of the discharge is increased. The reproducibility of the experiments and the relatively high sensitivity of the proposed method are underlined. [ABSTRACT FROM AUTHOR]

The electrodeposition of copper-selenium binary compounds on gold electrode was investigated in the choline chloride – urea (ChCl-U) deep eutectic solvent at 110 °C. Cyclic voltammetry and potentiostatic deposition followed by stripping voltammetries were employed to gain thermodynamic insights pointing to the formation of Cu 2 Se, which is supported by X-Ray Photoelectron Spectroscopy. The electrochemical stability domain of the compound is about 900 mV (from ≈−0.81 V to ≈+0.07 V vs. a silver quasi-reference electrode) and is consistent with the thermodynamics of induced co-deposition. The domain is limited at positive potentials by the oxidation to Se(0) and at negative potentials by the reduction to Cu(0). While copper is readily deposited on the gold electrode, the electrodeposition of selenium requires a significant overpotential. As a consequence, copper is kinetically favoured in the co-deposition and is present in its pure form at short deposition times. This is circumvented by using longer deposition times or more negative potentials. Photoelectrochemical measurements show that the as-deposited compound behaves as a p-type semiconductor. [ABSTRACT FROM AUTHOR]

Abstract: The interaction between the thrombin binding aptamer (TBA), a G-quadruplex forming DNA sequence, and the electroactive hexaammineruthenium(III) cation has been studied by electrochemical methods and circular dichroism spectroscopy. When TBA is immobilised on a gold surface in a typical aptasensor configuration, the [Ru(NH3)6]3+ cation can be bound to the electrode surface through its interaction with the TBA sequence. This interaction is strong enough to enable the ruthenium complex to remain at the surface when the electrode is immersed in an electrolyte free of [Ru(NH3)6]3+, meaning that the complex does not diffuse back into the solution. A stoichiometry of 2 [Ru(NH3)6]3+ per TBA strand has been determined, indicating that the interaction differs from the conventional, non-specific electrostatic charge compensation, for which a 5 to 1 ratio would be expected between the triply charged cation and the 15 bases sequence. It is shown that this interaction takes place not only at the surface, but also when both TBA and hexaammineruthenium(III) are dissolved in solution. Under such conditions, a similar stoichiometry of 2 [Ru(NH3)6]3+ per TBA strand has been evidenced by two independent methods, namely circular dichroism spectroscopy and differential pulse voltammetry. [Copyright &y& Elsevier]

Abstract: MoSe2 single crystals were grown by chemical vapor transport using TeCl4 as transport agents in the temperature gradient 1020–980 °C. They were characterized by scanning electron microscopy (SEM), optical microscopy, image analysis coupled with SEM, microanalysis by SEM-EDX, X-ray fluorescence, inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS) and electrical conductivity. The characterizations showed that single crystals are perfectly homogeneous, stoichiometric and have very few defects and clean surfaces with areas in the range of 35–100 mm2. Single crystals grown by TeCl4 showed a high electrical conductivity. Their properties were highly dependent on the quality of the polycrystalline powders used for the growth. [Copyright &y& Elsevier]

Potential controlled electrolyses of [BMIm][NTf 2 ] ionic liquid were performed at a gold cathode under nitrogen atmosphere. The structures of the major conversion products of the BMIm + cation were elucidated on the basis of 1D and 2D nuclear magnetic resonance (NMR) analyses and gas chromatography (GC) analysis of the volatile compounds. Recombination of the imidazol-2-yl radicals, generated at the electrode by single electron transfer, leads to neutral diastereomeric dimers in equal proportions, with a faradaic efficiency of 80 %, while disproportionation of these radicals and/or reaction with hydrogen atoms adsorbed at the electrode generates a neutral monomer with 20 % faradaic efficiency. Both pathways also yield the N-heterocyclic carbene imidazolin-2-ylidene, which is involved in fast proton exchange with the parent BMIm + cation. The reductive decomposition products of the BMIm + cation are no longer detected if the pre-electrolysed sample is reacted with CO 2 , which undergoes an indirect reduction and generates the carboxylate adduct., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Aptamer-based biosensors offer promising perspectives for high performance, specific detection of proteins. The thrombin binding aptamer (TBA) is a G-quadruplex-forming DNA sequence, which is frequently elongated at one end to increase its analytical performances in a biosensor configuration. Herein, we investigate how the elongation of TBA at its 5' end affects its structure and stability. Circular dichroism spectroscopy shows that TBA folds in an antiparallel G-quadruplex conformation with all studied cations (Ba(2+), Ca(2+), K(+), Mg(2+), Na(+), NH(4)(+), Sr(2+) and the [Ru(NH(3))(6)](2+/3+) redox marker) whereas other structures are adopted by the elongated aptamers in the presence of some of these cations. The stability of each structure is evaluated on the basis of UV spectroscopy melting curves. Thermal difference spectra confirm the quadruplex character of all conformations. The elongated sequences can adopt a parallel or an antiparallel structure, depending on the nature of the cation; this can potentially confer an ion-sensitive switch behavior. This switch property is demonstrated with the frequently employed redox complex [Ru(NH(3))(6)](3+), which induces the parallel conformation at very low concentrations (10 equiv per strand). The addition of large amounts of K(+) reverts the conformation to the antiparallel form, and opens interesting perspectives for electrochemical biosensing or redox-active responsive devices., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Hexaazatrinaphthylene (HATNA) derivatives with six alkylsulfanyl chains of different length (hexyl, octyl, decyl and dodecyl) have been designed to obtain new potential electron-carrier materials. The electron-deficient nature of these compounds has been demonstrated by cyclic voltammetry. Their thermotropic behaviour has been studied by means of differential scanning calorimetry and polarised optical microscopy. The supramolecular organisation of these discotic molecules has been explored by temperature-dependent X-ray diffraction on powders and oriented samples. In addition to various liquid crystalline columnar phases (Col(hd), Col(rd)), an anisotropic plastic crystal phase is demonstrated to exist. The charge-carrier mobilities have been measured with the pulse-radiolysis time-resolved microwave-conductivity technique. They are found to be higher in the crystalline than in the liquid crystalline phases, with maximum values of approximately 0.9 and 0.3 cm(2) V(-1) s(-1), respectively, for the decylsulfanyl derivative. Mobilities strongly depend on the nature of the side chains.