Argentophilic Interactions

The decade 1990–2000 saw a growing interest in aurophilic interactions in gold chemistry. These interactions were found to influence significantly a variety of structural and other physical characteristics of gold(I) compounds. The attention paid to this unusual and counterintuitive type of intra‐ and intermolecular bonding between seemingly closed‐shell metal centers has rapidly been extended to also include silver chemistry. Hundreds of experimental and computational studies have since been dedicated to the argentophilicity phenomenon. The results of this development are reviewed herein focusing on molecular systems where two or more silver(I) centers are in close contact leading to specific structural characteristics and a variety of novel physical properties. These include strongly modified ligand‐to‐metal charge‐transfer processes observed in absorption and emission spectroscopy, but also colossal positive and negative thermal expansion on the one hand and unprecedented negative linear compressibility of crystal parameters on the other.     

Robust classification for skewed data

In this paper we propose a robust classification rule for skewed unimodal distributions. For low dimensional data, the classifier is based on minimizing the adjusted outlyingness to each group. In the case of high dimensional data, the robustified SIMCA method is adjusted for skewness. The robustness of the methods is investigated through different simulations and by applying it to some datasets.     

Some remarks on the genesis of scalar-tensor theories

Between 1941 and 1962, scalar-tensor theories of gravitation were suggested four times by different scientists in four different countries. The earliest originator, the Swiss mathematician W. Scherrer, was virtually unknown until now whereas the chronologically latest pair gave their names to a multitude of publications on Brans–Dicke theory. P. Jordan, one of the pioneers of quantum mechanics and quantum field theory, and Y. Thiry, known by his book on celestial mechanics, a student of the mathematician Lichnerowicz, complete the quartet. Diverse motivations for and conceptual interpretations of their theories will be discussed as well as relations among them. Also, external factors like language, citation habits, or closeness to the mainstream are considered. It will become clear why Brans–Dicke theory, although structurally a déjà-vu, superseded all the other approaches.     

A molecular modeling study of pentanol solubilized in a sodium octanoate micelle

In order to study the structural and dynamical aspects of the solubilization process of pentanol within a sodium octanoate micelle a molecular dynamics simulation is presented. In this initial study we discuss the results and detailed insights into the interactions between sodium octanoate, pentanol, and water. The total micellar radius and the hydrophobic core radius were determined. The calculated values are in fairly good agreement with experimental results. In contrast to pure sodium octanoate micelles the aggregate with dissolved pentanol attained a more spherical shape related to the time interval of the simulation. It is clear that the results of a molecular dynamics computer simulation are always limited by its total length and the total time used for data analysis. Nevertheless, from our simulation study it turned out that a part of the pentanol hydroxyl groups were located within the micellar core and some alcohol molecules were also observed at the surface region of the micelle. The corresponding partition coefficient was calculated and agreed well with the experiment. The evaluated radial distribution functions of the sodium ions, the octanoate oxygens, and the hydroxyl hydrogens reveal details of the interface region of the micelle and the bulk phase. Additionally, it was possible to calculate the trans-to-gauche ratios of the alkyl chains and to compare these results with the simulation of a pure octanoate micelle.     

Integration of a membrane-based desalting step in a microfabricated disposable polymer injector for mass spectrometric protein analysis

A simple desalting procedure for the coupling of a polymer microchip injector to mass spectrometry is proposed. The overall process is based on the adsorption of proteins on a poly(vinylidene difluoride) (PVDF) membrane, which are then directly eluted in the spraying solution. This microchip-based approach has been successfully applied to small drugs, peptides and proteins originally diluted in phosphate-buffered saline (PBS). Moreover, when eluting the retained proteins in small volumes, a preconcentration is obtained. The combination of single-use, mass-produceable, low-sample-consumption, easy-to-automate, miniaturized polymer injectors with easy-to-handle solution-exchange membranes makes this system particularly amenable to screening applications.     

On Indecomposable and Imprimitive Modules for Finite Groups - A G-Algebra Approach

One of the most useful results in modular representation theoryof finite groups is Green's indecomposability theorem [4]. Inorder to state it in a simple form, let us fix a complete discretevaluation ring O of characteristic 0 with algebraically closedresidue field F of characteristic p0. Unless stated otherwise,all our modules will be free of finite rank over O or F, respectively.In its most popular form, Green's theorem says the following.     

Rates and mechanisms of indole and 3-Methylindole polymerization in cation exchange resin beads

Batch extraction and polymerization of indole and 3-methylindole (skatole) with acidic cation exchange resins functioned as pseudo first-order reactions. Activation energies of 3.4 and 5.7 keal/mole indicated greater steric hindrance to skatole polymerization, as would be expected from 2,2′ bonding of skatole compared to 3,2′ bonding for indole. Linear polymerization occurred, although a heterocyclic ring opened at the trimer stage of poly(indole). 2-Methylindole did not polymerize. General acid-base catalysis caused unreproducible partial depolytnerization when the polymers were extracted from resin beads. Thus, compounds chromatographically separated probably were of lower degree of polymerization than were the polymers formed in the resin matrix.