Nonlinear frequency response analysis: a recent review and perspectives

The nonlinear frequency response analysis (NFRA) can be seen as an extension of electrochemical impedance spectroscopy. NFRA gives a full and detailed representation of the system response and can establish a connection between model parameters and the experimentally observed phenomena. In this article, different theoretical NFRA approaches and the most recent application examples are discussed. A simple electrochemical example is used to showcase the benefits and disadvantages of analyzing the system response by using different approaches. In addition, it was shown how to extract experimental harmonic values and analyze them.     

Analysis of Corrugated Long-Period Gratings in Planar Waveguides and Their Polarization Dependence

We present a theoretical analysis of corrugated long-period gratings in planar waveguides. In particular, we calculate the transmission spectra for both the TE and TM polarizations and highlight the polarization-independence conditions.     

Addition of hydroxide to an isoelectronic series of bis-diazineplatinum(II) complex ions

Base hydrolysis of bis-bipyridylplatinum(II) occurs via a 1:1 intermediate adduct with hydroxide ion. The equilibrium constants for this 1:1 addition of hydroxide inwater to complex ions [PtL2]2+, where L=one of theisoelectronic set 2,2-bipyridyl (bpy); 2,2- bipyrazine (bpz); 3,3-bipyridazine (bpdz) and 2,2- bipyrimidine (bpym) are respectively (as log10K at 25°C): 4.23; 4.59; 3.82; 6.14. This result is rationalized in terms of addition at the 6–position of the ligand.     

Viscosities ofn-alkylamines from 15 to 80°C

The viscosities of seven n-alkylamines from n-butylamine to n-decylamine were determined from 15 to 80°C at 5°C intervals. The intrinsic volumes were determined by extrapolation of the plot of fluidity against molar volume to zero fluidity and found to be a linear function of the number of carbon atoms. Plots of the logarithm of viscosity vs. reciprocal absolute temperature were almost linear. The energies of activation for viscous flow for the n-alkylamines were calculated and found to increase with increase in the carbon number. The B values, based on Hildebrand's equation and representing a measure of a molecules resistance to transport of momentum, were calculated for each of the n-alkylamines. A modified form of the equation describing the change fluidity with temperature was then formulated. It is suggested that the activation energy for viscous flow consists of the sum of the energy required for the expansion of the void volume and the energy required to overcome intermolecular interactions. These energies were calculated and discussed.     

Alternative Approach to an AB2 Monomer for Hyperbranched Poly(Arylene Ether Ketone Imide)s

An alternative approach to an AB₂ monomer, N‐[3,5‐bis(4‐hydroxybenzoyl)benzene]‐4‐fluorophthalimde, 4, for hyperbranched poly(arylene ether ketone imide)s has been developed. The key steps were a para‐position selective electrophilic aromatic substitution of fluorobenzene with 5‐nitroisophthaloyl dichloride and a subsequent clean conversion of the aryl fluorides to phenol groups using potassium hydroxide as the nucleophile. The overall yield for the synthesis of 4 was 51.6%.     

Anti‐cancer potential of selenium‐ and tellurium‐containing species: opportunities abound!

An overview highlighting the anti‐cancer potential of (bio‐essential) selenium‐ and tellurium‐containing species, with an emphasis on biological targets and mechanisms of action, is presented. Studies thus far have focused on selenium(II) compounds (along with – to a lesser extent – inorganic selenium and selenium nanoparticles) which often successfully exploit the inherent anti‐oxidizing ability of selenium. Significantly less work has been conducted in developing anti‐cancer tellurium compounds, yet two tellurium(IV) species are proven, clinically, as anti‐cancer agents. Given the prevalence of the disease and the accumulated insights into mechanisms of action, the continued development of selenium‐ and tellurium‐containing molecules is an area deserving greater attention. Copyright © 2012 John Wiley & Sons, Ltd.