Compton profiles of solvated electrons

The importance of applying a variety of experimental techniques to unravel the nature of solvated electrons is emphasized. Compton profiles are evaluated for these species from a range of models. Some comparisons are made with positron annihilation studies.     

Synthesis of azahelicenes through Mallory reaction of imine precursors: corannulene substrates provide an exception to the rule in oxidative photocyclizations of diarylethenes

Typically, the synthesis of phenanthrene-based polycyclic aromatic hydrocarbons relies on the Mallory reaction. In this approach, stilbene (PhCH CHPh)-based precursors undergo an oxidative photocyclization reaction to join the two adjacent aromatic rings into an extended aromatic structure. However, if one C C carbon atom is replaced by a nitrogen atom (C N), the synthesis becomes practically infeasible. Here, we show the very first examples of a successful Mallory reaction on stilbene-like imine precursors involving the molecularly curved corannulene nucleus. The isolated yields exceed 90% and the resulting single and double aza[4]helicenes exhibit adjustable high affinity for electrons.

First azahelicene synthesis from corannulene-based imine precursors is presented.     

Thermodynamics for Coulomb systems: A problem at vanishing particle densities

In this paper I combine techniques recently developed by Charles Fefferman with the well-known methods of Joel Lebowitz and Elliott Lieb to resolve some technical problems left unsettled by Lebowitz and Lieb's fundamental 1972 paper The constitution of matter: Existence of thermodynamics for systems composed of electrons and nuclei.     

Separation scheme for the determination of alkali metals (K, Rb, Cs), alkaline earths (Sr, Ba) and rare earths (Ce, Nd, Sm, Eu) in silicate materials by isotopic dilution analysis

A scheme is outlined for the separation of Li, K, Rb, Cs, Sr, Ba, Ce, Nd, Sm and Eu from silicate materials. The elements are separated by cation-exchange to provide groups suitable for mass spectrometric analysis, and are then further purified by anion-exchange. Results obtained by isotopic dilution analysis are reported for G-1, W-1, and the Harwell meteorite-in these measurements the alkali metals were determined separately from the other elements. Requirements are discussed for combining the procedures to form a more comprehensive method for use with a single sample.     

Total Synthesis of (+)-okaramine J featuring an exceptionally facile N-reverse-prenyl to C-prenyl aza-Claisen rearrangement

[reaction: see text] The convergent total synthesis of (+)-okaramine J was achieved in a longest linear sequence of 12 steps from l-tryptophan tert-butyl ester. A key reaction was the acid-catalyzed room-temperature aza-Claisen rearrangement of a N-reverse-prenylated hexahydro[2,3-b]pyrroloindole to a C-prenylated derivative.     

The hole-pressure problem

There is a need to unify present hypotheses of the nature and role of the hole-pressure,p _e , and thus provide consolidation on which to base future research and understanding. This paper is intended to meet this need. Attention is directed towards the calculation ofp _e from the velocity and stress fields for viscoelastic fluids flowingacross rectangular holes. The constitutive models used are the Newtonian, Second-order and Maxwell models, for values of Reynolds number up to 10 and Weissenberg number up to 0.1.The numerical complications involved are studied through an investigation of the constituent parts ofp _e . Verification of present theory is then sought, from which justification may be derived for the estimation of elasticity fromp _e measurements. Attention is directed towards the predictions of Higashitani and Pritchard and the extension to the Tanner and Pipkin theory for Second-order fluids. The effects of variation of geometric dimensions and flow type uponp _e are also discussed.     

High-performance liquid chromatographic assay for pteroylpolyglutamate hydrolase

A highly sensitive assay for pteroylpolyglutamate hydrolase is described employing high-performance liquid chromatography (HPLC) with ultraviolet detection at 280 nm. The method is based on the separation of pteroylpolyglutamates containing various glutamyl residues on a C18 muBondapak reversed-phase column. Individual pteroylpolyglutamates are eluted by a gradient of 2.5-8.5% acetonitrile in 0.1 M potassium phosphate buffer (pH 6.0) within 20 min. The polyglutamates with higher glutamyl residues were less well retained in the reversed-phase column. The relationship between the peak area and the amount of pteroylpolyglutamate was observed to be linear over the range 10 pmol to 2.5 nmol. Human serum pteroylpolyglutamate hydrolase was studied using pteroylpentaglutamate as substrate in 0.1 M sodium acetate buffer (pH 4.5). The enzyme appeared to function as an exopeptidase based on the detection of intermediates, pteroyltetra-, tri-, and -diglutamate, and the product, pteroylmonoglutamate. Using the HPLC assay, extracts of Plasmodium falciparum were found not to contain detectable enzyme activity.