Experimental studies on the Kβ/Kα intensity ratio of Zn at different thickness and pressure

Kβ/Kα intensity ratios of Zn were measured at a photon excitation energy of using a high-resolution Si(Li) detector for several thickness at different pressure. Present results were compared with theoretical data and other experimental values. The results were in good agreement theoretical values based on Hartree-Fock theory.     

Phosphorus‐based Schiff bases and their complexes as nontoxic antioxidants: Structure–activity relationship and mechanism of action

Phosphorus‐based Schiff base were synthesized by treating bis{3‐[2‐(4‐amino‐1.5‐dimethyl‐2‐phenyl‐pyrazol‐3‐ylideneamino)ethyl]‐indol‐1‐ylmethyl}‐phosphinic acid with paraformaldehyde and characterized as a novel antioxidant. Its corresponding complexes [(VO)₂L(SO₄)₂], [Ni₂LCl₄], [Co₂LCl₄], [Cu₂LCl₄], [Zn₂LCl₄], [Cd₂LCl₄], [Hg₂LCl₄], [Pd₂LCl₄], and [PtLCl]Cl₂ were analyzed by Fourier transform‐infrared, (¹H and ¹³C) nuclear magnetic resonance, and mass and UV–Vis spectroscopy. Experimental data showed that the ligand coordinated with the metal ions via donor atoms such as nitrogen to form an octahedral arrangement of the Schiff base around the central transition‐metal atom. The nature of these complexes was identified using the molar ratio and Job's methods, with the results agreeing with a metal‐to‐ligand (M:L) molar ratio of 2:1, expect for Pt, whose M:L was 1:1. Thermodynamic activation parameters such as ?E*, ?H*, ?S*, ?G*, and K were determined from the thermogravimetric analysis curve using the Coats–Redfern method. The antioxidant activities of the prepared compounds were assessed by using 1.1‐diphenyl‐2‐picrylhydrazyl as the free radical, and the results show that the complex Schiff bases were found to possess potent antioxidant activity. The structure–activity relationship of the ligand and its complexes indicates that the presence of electron‐donating moieties, such as Co(II) and Ni(II), in the chemical structure increases the antioxidant activity, whereas the Pt(IV) and Pd(II) complexes diminished the antioxidant activity, indicating the superior activity of the hydroxyl radical (OH^·) over the superoxide radical.     

Design of novel substituted phthalocyanines; synthesis and fluorescence,DFT, photovoltaic properties

The 4-(2-[3,4-dimethoxyphenoxy] phenoxy) phthalonitrile was synthesized as the starting material of new syntheses. Zinc, copper, and cobalt phthalocyanines were achieved by reaction of starting compound with Zn(CH3COO)2, CuCl2, and CoCl2 metal salts. Basic spectroscopic methods such as nuclear magnetic resonance electronic absorption, mass and infrared spectrometry were used in the structural characterization of the compounds. Absorption, excitation, and emission measurements of the fluorescence zinc phthalocyanine compound were also investigated in THF. Then, structural, energy, and electronic properties for synthesized metallophthalocyanines were determined by quantum chemical calculations, including the DFT method. The bandgap of HOMO and LUMO was determined to be chemically active. Global reactivity (I, A, η, s, μ, χ, ω) and nonlinear properties were studied. In addition, molecular electrostatic potential (MEP) maps were drawn to identify potential reactive regions of metallophthalocyanine (M-Pc) compounds. Photovoltaic performances of phthalocyanine compounds for dye sensitive solar cells were investigated. The solar conversion efficiency of DSSC based on copper, zinc, and cobalt phthalocyanine compounds was 1.69%, 1.35%, and 1.54%, respectively. The compounds have good solubility and show nonlinear optical properties. Zinc phthalocyanine gave fluorescence emission.     

Description of the Effects of Non‐ion‐exchange Extraction and Intra‐membrane Interactions on the Ion‐selective Electrodes Response within the Interface Equilibria‐triggered Model

The recently proposed interface equilibria‐triggered dynamic diffusion model of the boundary potential has proven its high predictive efficiency for quantification of the ion exchange and co‐extraction effects at the interface, as well as of the trans‐membrane transfer effect, on the electrode response. It is applicable for both ion exchanger‐based and neutral carrier‐based electrodes. In this communication, the adaptability of this model to more complex cases, when non‐ion‐exchange extraction processes at the interface (partition of organic acids’ and bases’ molecular forms and extraction of ionic associates) are coupled with protolytic equilibria in the aqueous phase and with self‐solvation process in the membrane phase, is demonstrated. By the example of electrodes reversible to ions of highly lipophilic physiologically active bases and acids (amiodarone, verapamil, vinpocetine, salicylic acid), it is shown that the peculiarities of their functioning, such as a very strong pH effect on the potential of cation‐selective electrodes, non‐monotonic pH dependence of the potential and super‐Nernstian response slope in certain pH region for a salicylate‐selective electrode, are well described within the model.     

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.     

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.     

A novel concept for in situ gas-phase laser Raman spectroscopy for solid oxide fuel cell research

A planar solid oxide fuel cell (SOFC) operated with hydrogen at T = 1,123 K was equipped with an optically transparent anode flow field to apply species concentration measurements by 1D laser Raman scattering. The flow channels had a cross section of 3 mm × 4 mm and a length of 40 mm. The beam from a pulsed high-power frequency-doubled Nd:YAG laser (λ = 532 nm) was directed through one channel and the Raman-scattered light from different molecular species was imaged onto an intensified CCD camera. The main goal of the study was an assessment of the potential of this experimental configuration for a quantitative determination of local gas concentrations. The paper describes the configuration of the optically accessible SOFC, the laser system and optical setup for 1D Raman spectroscopy as well as the challenges associated with the measurements. Important aspects like laser pulse shaping, signal background and signal quality are addressed. Examples of measured species concentration profiles are presented.