DNA binding and nuclease activity of cationic iron(IV) and manganese(III) corrole complexes

Cationic meso(4‐N‐methylpyridyl)‐based metallocorroles, μ‐oxo iron corrole dimer ( 1b ) and manganese corrole monomer ( 2b ), were synthesized and characterized. The interactions of these two metal corrole complexes with CT‐DNA were studied by UV–visible, fluorescence and circular dichroism spectroscopic methods, as well as by viscosity measurements. The results revealed that 1b interacts with CT‐DNA in a difunctional binding mode, i.e. non‐classical intercalation and outside groove binding with H‐aggregation, while 2b can interact with CT‐DNA via an outside groove binding mode only. The binding constants K_b of 1b and 2b were 4.71 × 10⁵ m ^?1 and 2.17 × 10⁵ m ^?1, respectively, indicating that 1b can bind more tightly to CT‐DNA than 2b . Furthermore, both complexes may cleave the supercoiled plasmid DNA efficiently in the presence of hydrogen peroxide or tert‐butyl hydroperoxide (TBHP), albeit 1b exhibited a little higher efficiency. The inhibitor tests suggested that singlet oxygen and high‐valent (oxo)iron(VI) corrole or (oxo)manganese(V) corrole might be the active intermediates responsible for the oxidative DNA scission. Copyright © 2014 John Wiley & Sons, Ltd.     

Structure, phase formation, and wetting behavior of BaO–SiO2–B2O3 based glass–ceramics as sealants for solid oxide fuel cells

In the present study, glasses from the three different compositional triangles in the BaO–B₂O₃–SiO₂ system with fixed B₂O₃/SiO₂ ratio and different BaO/SiO₂ molar ratios (designated as Ba32, Ba37, and Ba42) were prepared, and suitability of them as sealant in solid oxide fuel cells were investigated. Structure of the glasses was characterized with Raman spectroscopy. According to the results, the structure of the glass with 32 % molar BaO (Ba32) predominantly consisted of Q² structural species. In glasses with 37 and 42 % molar BaO (Ba37 and Ba42), with the substitution of SiO₂ by BaO, distribution of Qⁿ units widened, silicate glass network depolymerized, and concentration of Q¹ structural units increased at the expense of Q² units. X-ray diffraction analyses revealed that in samples Ba32 and Ba37, initially, Ba₃Si₅O₁₃ and Ba₅Si₈O₂₁ phases were crystallized, respectively, and it seemed they acted as the sites for the subsequent growth of BaSi₂O₅ phase. In contrast, the dominant phase in sample Ba42 was Ba₂Si₃O₈. Sintering, wetting, and crystallization behavior of the glasses were studied using hot-stage microscopy and differential thermal analysis, respectively. Delay in the crystallization accompanied by depolymerization of the structure led into deformation at lower temperatures and greater wettability on the steel for Ba37 glass. All the glasses wetted AISI430 alloy at temperatures higher than 1,000 °C.     

Entanglement Evolution Between Various Subsystems of Two Three-level Atoms Interacting with a Two-mode Quantized Field in the Presence of Converter Terms

In this paper, we study the interaction between two Λ-type three-level atoms (a typical qutrit-qutrit system) and two coupled modes of a quantized radiation field in the presence of field-field interaction (parametric down conversion) which are simultaneously injected within an optical cavity. Then, by applying an appropriate canonical transformation, the introduced model is reduced to a well-known form of the generalized Jaynes-Cummings model. Under particular initial conditions for atoms (in some possible states) and the fields (in the finite dimensional pair coherent state) which may be prepared, the explicit form of the state vector of the whole system is analytically evaluated. In order to find the degree of entanglement between different parts of subsystems (“atom+atom”-field, “atom+field”-atom and atom-atom) the dynamics of entanglement through different measures, namely, linear entropy and negativity is evaluated. In each case, the effect of various types of initial atomic states on the above measures are numerically analyzed, in detail. It is indicated that the amount of entanglement can be tuned by choosing appropriate initial states of atoms. Particularly, it is shown that the entanglement sudden death (ESD) can be controlled by adjusting the initial state of the atoms.     

Facile and scalable fabrication of graphene/polypyrrole/MnO<Subscript>x</Subscript>/Cu(OH)<Subscript>2</Subscript> composite for high-performance supercapacitors

In this study, to improve the specific capacitance of graphene-based supercapacitor, novel quadri composite of G/PPy/MnO_x/Cu(OH)₂ was synthesized by using a facile and inexpensive route. First, a two-step method consisting of thermal decomposition and in situ oxidative polymerization was employed to fabricate graphene/polypyrrole/manganese oxide composites. Second, Cu(OH)₂ nanowires were deposited on Cu foil. Afterwards, for the electrochemical measurements, composite powders were deposited on Cu(OH)₂/Cu foil substrate as working electrodes. The synthesized samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR) spectroscopy, and Raman spectroscopy. The XRD analysis revealed the formation of PPy/graphene, Mn₃O₄/graphene, and graphene/polypyrrole/MnO_x. In addition, the presence of polypyrrole and manganese oxides was confirmed using FT-IR and Raman spectroscopies. Graphene/polypyrrole/MnO_x/Cu(OH)₂ electrode showed the best electrochemical performance and exhibited the largest specific capacitance of approximately 370 F/g at the scan rate of 10 mV/s in 6 M KOH electrolyte. In addition, other electrochemical measurements (charge–discharge, EIS and cyclical performance) of the G/Cu(OH)₂, G/PPy/Cu(OH)₂, G/Mn₃O₄/Cu(OH)₂, and G/PPy/MnO_x/Cu(OH)₂ electrodes suggested that the G/PPy/MnO_x/Cu(OH)₂ composite electrode is promising materials for supercapacitor application.