Investigating the Mechanism and Electrode Kinetics of the Oxygen vertical bar Superoxide (O-2 vertical bar O-2(center dot-)) Couple in Various Room-Temperature Ionic Liquids at Gold and Platinum Electrodes in the Temperature Range 298-318 K

The reduction of oxygen was studied over a range of temperatures (298-318 K) in n-hexyltriethylammonium bis(trifluoromethanesulfonyl)imide, [N-6,N-2,N-2,N-2][NTf2], and 1-butyl-2,3-methylimidazolium bis(trifluoromethanesulfonyl)imide, [C(4)dmim][NTf2] on both gold and platinum microdisk electrodes, and the mechanism and electrode kinetics of the reaction investigated. Three different models were used to simulate the CVs, based on a simple electron transfer ('E'), an electron transfer coupled with a reversible homogeneous chemical step ('ECrev') and an electron transfer followed by adsorption of the reduction product ('EC(ads)'), and where appropriate, best fit parameters deduced, including the heterogeneous rate constant, formal electrode potential, transfer coefficient, and homogeneous rate constants for the ECrev mechanism, and adsorption/desorption rate constants for the EC(ads) mechanism. It was concluded from the good simulation fits on gold that a simple E process operates for the reduction of oxygen in [N-6,N-2,N-2,N-2][NTf2], and an ECrev process for [C(4)dmim][NTf2], with the chemical step involving the reversible formation of the O-2(center dot-)center dot center dot center dot [C(4)dmim](+) ion-pair. The E mechanism was found to loosely describe the reduction of oxygen in [N-6,N-2,N-2,N-2][NTf2] on platinum as the simulation fits were reasonable although not perfect, especially for the reverse wave. The electrochemical kinetics are slower on Pt, and observed broadening of the oxidation peak is likely due to the adsorption of superoxide on the electrode surface in a process more complex than simple Langmuirian. In [C(4)dmim][NTf2] the O-2(center dot-) predominantly ion-pairs with the solvent rather than adsorbs on the surface, and an ECrev quantitatively describes the reduction of oxygen on Pt also.

Novel genomic methods for drug discovery and mechanism-based toxicological assessment

Genomics encompasses a range of powerful technologies that can be applied at all levels of gene expression, from transcription to mRNA translation. Collectively, these technologies have great potential for improving drug discovery, both target and molecule recognition, and development. In this article we review the current and potential future status of established and novel genomic methods within drug discovery.

On the mechanism for optomechanical entanglement and its revelation

An intuitive and accurate picture of the occurrence of optomechanical entanglement in a system of great current experimental interest is provided. At the optimal working point for entanglement generation, the interaction of a light field with a micromechanical oscillator is described in terms of simple SU( 2) transformations. This allows the analysis of a recent proposal for the revelation of quantumness in the state of a massive mirror from a clear and experimentally biased viewpoint.

Suggested Binding Mechanism of the HIV-gp120 to its CD4 Receptor

The molecular recognition and attachment of the CD4 molecule and the HIV envelope glycoprotein (gp120) might be described as a consecutive three-step molecular recognition process. 1. (a) Long range interaction: electrostatic pre-orientation, 2. (b) short range interaction: electronic attachment followed by a ‘Locking-in’ (via aromatic ring orientation) and 3. (c) internal interaction (induced fit): conformational readjustment of the protein molecules. On the basis of the preliminary investigations (X-ray structures of CD4 and biological studies of CD4 and gp120 point mutants) we described a computational model. This approach consists of empirical calculations as well as ab initio level of quantum chemistry. The conformational analysis of the wild type and mutant CD4 molecules was supported by molecular mechanics and dynamics (Amber force field). The latter analysis involves the application of a novel method, the Amino Acid Conformation Assignment of Proteins (ACAP) software, developed for the notation of secondary protein structures. According to the cardinal role of the electrostatic factors during this interaction, several ab initio investigations were performed for better understanding of the recognition process on submolecular level. Using the above mentioned computational model, we could interpret the basic behaviours and predict some additional features of CD4-gp120 interaction, in spite of the missing gp120 X-ray structure.

Hypercapnic acidosis attenuates pulmonary epithelial wound repair by an NF-kappa B dependent mechanism

Background: Hypercapnic acidosis exerts protective effects in acute lung injury but may also slow cellular repair. These effects may be mediated via inhibition of nuclear factor-kappa B (NF-kappa B), a pivotal transcriptional regulator in inflammation and repair.