ABSTRACT
Blends of PVA and 2-nitroso-1-naphtol-4-sulfonic acid (NNSA) ranging from 10 to 40 wt% were crosslinked in the presence of glutaraldehyde (GLA) to produce hybrid membranes. The structure and morphology of the hybrid membranes were studied by XRD, FE-SEM, EDX, and elemental mapping experiments. The mechanical performance and thermal stability of the membranes were also examined by dynamic mechanical analysis (DMA) and thermogravimetry analysis (TGA), respectively. Increasing the concentration of NNSA resulted in the improvement of mechanical and thermal performances of the membrane. The addition of NNSA and SiO2 to the solution of PVA makes the resultant hybrid membrane more hydrophilic, and therefore, the proton conductivity, water uptake and ion exchange capacity (IEC) improved. The highest proton conductivity value (0.18 S cm-1 at 30 °C) was found for the PVA/GLA/NNSA (40 wt%)/SiO2 (5 wt%) composite membrane. It was also demonstrated that the methanol permeability values decreased with increasing NNSA content.
ABSTRACT
Interaction of 1,3-bis(2-hydroxy-benzylidene)-urea (H2L1), 1,3-bis(2-hydroxy-3-methoxy-benzylidene)-urea (H2L2) and 1,3-bis(2-hydroxy-3-methoxy-benzylidene)-urea nickel(II) (NiL2) with calf-thymus DNA were investigated by UV-vis absorption, fluorescence emission and circular dichroism (CD) spectroscopy as well as cyclic voltammetry, viscosity measurements, molecular docking and molecular dynamics simulation. Binding constants were determined using UV-vis absorption and fluorescence spectra. The results indicated that studied Schiff-bases bind to DNA in the intercalative mode in which the metal derivative is more effective than non metals. Their interaction trend is further determined by molecular dynamics (MD) simulation. MD results showed that Ni derivative reduces oligonucleotide intermolecular hydrogen bond and increases solvent accessible surface area more than other compounds.
