μSR studies of the vortex lattice in high‐Tc and other superconductors

We review some of the assumptions made in the use of muon spin rotation in superconductors: i.e. that the muons are implanted at random positions in the flux lattice, remain static after implantation and do not appreciably affect the properties of the surrounding superconductor; also that the flux lines are straight and static, and that the observed muon rotation frequency spectrum reflects the microscopic distribution of field values. We shall show how evidence for and against the truth of these assumptions in particular cases may be obtained from the μSR results themselves or by comparison with other measurements, and how this in turn may lead to deeper understanding of flux line structure and motion in superconductors. This revised version was published online in August 2006 with corrections to the Cover Date.     

A rapid procedure for obtaining hydrodynamic voltammetry plots for electrochemical detectors in high-pressure liquid chromatography systems

The construction of relatively simple and inexpensive apparatus for the determination of the operating conditions for electrochemical detectors in high-pressure liquid chromatography systems is described. A procedure has been developed for the characterization of electrochemically active compounds.     

3-Hydroxy-1,4-diphenyl-7-oxabicyclo[4.1.0]hept-3-ene-2,5-dione. A microbial product from streptomyces species (AAA566)

The epoxyenedione 1a has been isolated from a strain $\text{Streptomyces}$ and its structure has been established by nmr spectroscopy and by its conversion to 2,5-diphenyl-3,4-dihydroxyphenol. Selective hetero J-resolved nmr spectroscopy played a pivotal role in the structure elucidation.     

Phase inversion sulfonated polysulfone membranes

The use of two nonsolvents serving as a cosolvent system, replacing the traditional volatile solvent plus less volatile nonsolvent system, in the formation of asymmetric phase inversion membranes was investigated. Specifically, asymmetric membranes of sulfonated polysulfone were cast from a cosolvent system consisting of tetrahydrofuran and formamide. The nonsolvents and the proportions in which they are mixed to produce the cosolvent system, as well as the gelation medium isopropyl alcohol, were selected based on the three-component solubility parameter concept of Hansen. The structure of each membrane was evaluated using scanning electron microscopy; the performance was evaluated for use in pressure-driven membrane separation processes. The membranes were found to be dependent on the composition of the original casting solution and the composition of the nascent membrane at the instant of gelation. These ideas are clearly represented through the use of a triangular polymer solubility diagram.     

Magnetic circular dichroism of the 3B3μ ← 1 Ag excitation in pyrazine

The magnetic circular dichroism spectrum of the lowest lying singlet—triplet transition of pyrazine is reported. The experimental data are in accord with theoretical predictions based upon the assumption of Hund's case (b) coupling in the ³B_3u state.     

The preparation of triazines and benzimidazoles from 1- and 3-cyanoisoquinolines

The preparation from 1- and 3-cyanoisoquinolines of certain benzimidazoles and symmetrical triazines containing the ferroin group is described; also that of certain unsymmetrical triazines from 3-cyanoisoquinoline.