Standardized experiments in mutant mice reveal behavioural similarity on 129S5 and C57BL/6J backgrounds.

Behavioural analysis of mice carrying engineered mutations is widely used to identify roles of specific genes in components of the mammalian behavioural repertoire. The reproducibility and robustness of phenotypic measures has become a concern that undermines the use of mouse genetic models for translational studies. Contributing factors include low individual study power, non-standardized behavioural testing, failure to address confounds and differences in genetic background of mutant mice. We have examined the importance of these factors using a statistically robust approach applied to behavioural data obtained from three mouse mutations on 129S5 and C57BL/6J backgrounds generated in a standardized battery of five behavioural assays. The largest confounding effect was sampling variation, which partially masked the genetic background effect. Our observations suggest that strong interaction of mutation with genetic background in mice in innate and learned behaviours is not necessarily to be expected. We found composite measures of innate and learned behaviour were similarly impacted by mutations across backgrounds. We determined that, for frequently used group sizes, a single retest of a significant result conforming to the commonly used P < 0.05 threshold results in a reproducibility of 60% between identical experiments. Reproducibility was reduced in the presence of strain differences. We also identified a P-value threshold that maximized reproducibility of mutant phenotypes across strains. This study illustrates the value of standardized approaches for quantitative assessment of behavioural phenotypes and highlights approaches that may improve the translational value of mouse behavioural studies.

Probing the electrochemical double layer of an ionic liquid using voltammetry and impedance spectroscopy: a comparative study of carbon nanotube and glassy carbon electrodes in [EMIM](+)[EtSO(4)](-).

Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are compared as techniques for analyzing double layer capacitances of ionic liquids (ILs) at the surfaces of two carbon-based electrodes. These systems are relevant for energy storage supercapacitors and often are associated with unconventional electrochemical properties. Certain theoretical and experimental aspects of CV and EIS necessary for quantitative evaluation of the capacitance characteristics of such systems are explored. The experiments use 1-ethyl-3-methyl imidazolium ethylsulfate as a model IL electrolyte in combination with a porous electrode of carbon nanotubes (CNTs). The results are compared with those obtained with a nonporous glassy carbon (GC) electrode. The time is constant, and hence the power delivery characteristics of the experimental cell are affected by the electrolyte resistance and residual faradaic reactions of the IL, as well as by the spatially inhomogeneous electrode surfaces. It is shown that adequate characterization of these IL-electrode systems can be achieved by combining CV with EIS. A phenomenological framework for utilizing this combination is discussed.

D.C. voltammetry of ionic liquid-based capacitors: effects of Faradaic reactions, electrolyte resistance and voltage scan speed investigated using an electrode of carbon nanotubes in EMIM-EtSO4.

Carbon nanotube (CNT) electrodes in combination with ionic liquid (IL) electrolytes are potentially important for energy storage systems. We report electrochemical investigation of such a system involving a paper-electrode of multi-wall CNT (MWCNT) in the IL of 1-ethyl-3-methyl imidazolium ethylsulfate (EMIM-EtSO(4)). Our study concentrates on the analytical aspects of cyclic voltammetry (CV) to probe the double layer capacitance of these relatively unconventional systems (that involve rather large charge-discharge time constants). Both theoretical and experimental aspects of CV for such systems are discussed, focusing in particular, on the effects of Faradaic side-reactions, electrolyte resistance and voltage scan speeds. The results are analyzed using an electrode equivalent circuit (EEC) model, demonstrating a method to account for the typical artifacts expected in CV of CNT-IL interfaces.

Surface plasmon resonance as a time-resolved probe of structural changes in molecular films: considerations for correlating resonance shifts with adsorbate layer parameters.

Surface plasmon resonance (SPR) spectroscopy is an efficient probe of transient structural changes in molecular films. To analyze kinetic SPR data for such systems, generally it is necessary to adapt an adequate theoretical framework that would allow one to express the measured optical quantities (time-dependent shifts of the resonance angle or wavelength) in terms of the structural parameters (layer thickness, mass density, or surface coverage) of the sample molecules. We present here theoretical calculations and illustrative experimental results to address certain essential elements of this type of data analysis for transient SPR systems. The phenomenological framework we consider here is based on multilayer reflectivity calculations, and can be applied to a broad class of systems involving ordered molecular layers on supporting gold films. A typical application of these calculations is demonstrated through the analysis of specific SPR experiments designed to probe the kinetics of pH-induced structural changes in a molecular film of 11-mercaptoundecanoic acid (MUA) on a thin gold film.

Combining impedance spectroscopy with cyclic voltammetry: measurement and analysis of kinetic parameters for faradaic and nonfaradaic reactions on thin-film gold.

The technique of time-resolved impedance spectroscopy can be combined with dc cyclic voltammetry (CV) to study mechanisms and kinetics of electrochemical reactions at solid-liquid interfaces. Utilization of these techniques in a combined framework, however, is based on a number of specific considerations of measurement procedures and data analysis. The present work discusses certain essential elements of this topic, focusing primarily on the analysis of time-resolved impedance spectra where interdependent dc and ac effects of parallel faradaic and nonfaradaic reactions are present under potentiodynamic conditions. A thin gold film is used as a model experimental system where oxidation and reduction of the sample surface is voltage-controlled both in the presence and in the absence of specifically adsorbing Cl- ions in neutral background electrolytes of NaF. Impedance spectra are recorded under transient conditions of CV, and kinetic parameters based on electrode-equivalent circuit models are obtained as functions of CV scans.