Modification of gold electrode by self-assembled 2-mercapto benzothiazole for the determination of Hg2+

An electrochemical method was developed for the determination of mercury using polycrystalline gold electrode modified by self-assembled monolayers (SAMs) of 2-mercaptobenzothiazole (MBTH). Morphological and electrochemical characterisation of the self-assembled structure of MBTH was performed using atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS) measurements. The monolayer of MBTH has shown high affinity for Hg²⁺. The limit of detection for the determination of Hg²⁺ using the MBTH SAMs modified gold electrode was obtained as 0.421 μg L^?1. The pre-concentration of Hg²⁺ at open circuit potential is beneficial for the onsite monitoring of mercury concentration in water samples.     

NONCONVENTIONAL EMULSION POLYMERIZATION OF ACRYLONITRILE CATALYZED BY in situ METAL COMPLEXw

 Nano-sized polyacrylonitrile (PAN) particles were prepared under the catalytic effect of in situ developed CoCl₂/EDTA complex with ammonium persulfate as the initiator in the absence of any added emulsifier. The emulsion polymerization was studied at varying concentrations of the initiator, monomer, complex and solvent over a temperature range of 30-70^oC. The overall activation energy (Ea, 49.79 kJ/mol), energy of dissociation of initiator (Ed, 82.68 kJ/mol), number of micelles (0.163 x 1018) and the viscosity average molecular weight of the polymer were computed. The distribution of particle sizes was determined by transmission electron microscopy (TEM). It was found that the oil-in-water polymerization was stabilized by the presence of the CoCl₂/EDTA in situ complex reducing the particle size into the nano order. The average diameters of PAN nano particles, obtained by TEM, were in the range of 50–150 nm at the maximum conversion. The experimental particle size was mainly dependent on the concentration of the complex and temperature.     

Re-examining scale elasticity in DEA

We propose a new scheme for measuring scale elasticity of production based on a new cost efficiency model developed in Tone (2002). Comparing our model with classical model we establish the superiority of our model over the latter based on the premise that the classical estimates of cost efficiency and scale elasticity can be illusory.     

Effect of electron-withdrawing groups on photovoltaic performance of thiophene-vinyl-thiophene derivative and benzochalcogenadiazole based copolymers: A computational study

We report a density functional theory study of the effect of electron-withdrawing groups such as –F, –CN, –NO₂ on the geometrical, optoelectronic, intramolecular charge transfer (ICT), and photovoltaic properties of (E)-1,2-bis(5-alkyl-[2,3′-bithiophene]-2′-yl)ethene (TVT-T) based donor-acceptor (D-A) copolymers with different acceptor units, that is, benzo[c][1,2,5]thiadiazole, benzo[c][1,2,5]oxadiazole, and benzo[c][1,2,5]selenadiazole. The computed optical absorption spectra of the designed compounds lie in the visible and near-infrared regions. Of all the studied copolymers, -CN substituted and Se-based compound displays the lowest HOMO-LUMO (E _{H - L}) gap and optical band gap (E _opt). The exciton binding energy (E _b) is found to be smaller for O-incorporated compounds and -CN substituted copolymer as well, inferring more ICT. The electron-hole coherence concentrated over the D-A units is nearly the same for -CN and -NO₂ substituted compounds, but larger in -F derivatives, indicating weak electron-hole coupling in the formers. Comparatively larger dipole moment (6.421 Debye-9.829 Debye) and charge transfer length (D _CT) (1.976 Å-3.122 Å) for -CN derivatives lead to enhanced ICT properties. The designed donors yield good hole mobilities (0.127-6.61 cm² V⁻¹ s⁻¹) and the predicted power conversion efficiencies are calculated to be as high as ~6%-7% for –CN and –NO₂ substituted compounds.     

Neutron dose estimation for 1H+9Be and 1H+12C reactions at 20 MeV proton energy via LET spectrometry using CR-39 detectors

The neutron dose is estimated by linear energy transfer (LET) spectrometry method for two reactions, viz. ¹H+⁹Be and ¹H+¹²C at 20 MeV proton energy using CR-39 track detectors. The LET spectrum is generated from the major, minor radii of each track and thickness of removed surface from each side of the detector due to chemical etching. Microdosimetric distributions of absorbed dose and dose equivalents are obtained from the LET spectrum. The absorbed dose and dose equivalent per incident proton obtained from the LET spectra are found to be about 12.5 and 8 times higher in ¹H+⁹Be reaction than ¹H+¹²C reaction.     

Real time band selective F1‐decoupled proton NMR for the demixing of overlay spectra of chiral molecules

The small chemical shift dispersion and complex multiplicity pattern in proton NMR limit quantifications, for instance the determination of enantiomeric excess (ee) for an enantiomeric mixture. Herein, we present a simple proton–proton correlation experiment with band selective homonuclear (BASH) decoupling in both F₁ and F₂ dimensions, for the removal of scalar and residual dipolar couplings to provide collapsed singlet for each chemical site. The method has been demonstrated to separate the severely overlapped spectra of enantiomers using both chiral isotropic and anisotropic phases as well as a small biomolecule, particularly for the diastereotopic protons and also for the determination of ee. Copyright © 2016 John Wiley & Sons, Ltd.