Fast-atom bombardment mass spectrometry of conjugated benzo(a)pyrene metabolites

Fast-atom bombardment mass spectrometry has been used to obtain spectra of conjugated benzo(a)pyrene (bap) metabolites using a 1:1, glycerol + thioglycerol matrix, bap Glucuronides give positive- and negative-ion spectra with peaks due to [M + H]+ and [M - H]- ions and a major fragment peak (base peak) at [bap-OH]+ and [bap-O]-. bap Sulfates (sodium salts) give similar negative-ion spectra with [M - Na]- and [bap-O]- peaks, but the positive-ion spectra are dominated by sodium and glycerol adducts of the bap sulfates.     

Pronounced stabilisation of the ferrocenium state of ferrocenecarboxylic acid by salt bridge formation with a benzamidine

Salt bridge formation between ferrocenecarboxylic acid and an excess of a N,N^′-diethylsubstituted benzamidine leads to a −0.27 V shift in the half-wave potential of the ferrocene moiety, corresponding to a 26 kJ mol⁻¹ stabilisation of the ferrocenium state.     

Whiteboard math movies

In this article, we discuss whiteboard math movies (a.k.a. mathcasts)and their applications to mathematics education. A whiteboardmath (wbm) movie is a screen recording of writing plus voiceand/or text explaining a mathematical concept or solving a problem.The movie is then produced to Flash movie format and distributedvia CD or Internet. The wbm movies are the ultimate in asynchronouslearning—providing a simple and inexpensive means of interactionat the teacher–student, teacher–teacher, student–teacherand student–student level. With wbm movies both the creatorand the viewer get to see and hear the mathematical thinkingstep-by-step. They get the process and not just the result andthey can have it when and as many times as they want. We talkabout how Tim Fahlberg came up with this idea over 8 years agoand describe the developments in technology—that are atleast partially the result of our team's work—that nowmake wbm movie making a cost-efficient, effective and even afun way of truly learning mathematics.     

Double-exchange ferromagnetism in the partially-filled one-dimensional Kondo lattice model

We investigate the incompletely saturated ferromagnetic phase which occurs at strong-coupling in the partially-filled one-dimensional (1D) Kondo lattice model. The double-exchange interaction responsible for the ferromagnetic ordering is absent in dilute Kondo systems, and is a missing element in nearly all theoretical treatments of the model. We discuss how: 1) double-exchange arises in the system, even though the Kondo coupling is antiferromagnetic, and show that at strong-coupling it favors an alignment of the spins of unpaired localized moments; and 2) how this determines the ground-state phase diagram, and properties of the localized moments.     

Stored positrons for antihydrogen production

The production of antihydrogen is examined in the light of recent experimental results on a technique for the efficient accumulation, manipulation, and storage of positrons. From these data, we argue that this high-efficiency positron trapping technique could be adapted for the production of antihydrogen and would offer significant advantages over other positron trapping techniques currently being proposed for this purpose. This revised version was published online in August 2006 with corrections to the Cover Date.     

Topological and bornological characterisations of ideals in von Neumann algebras: I

Suppose is a von Neumann algebra on a Hilbert space and is any ideal in . We determine a topology on , for which the members of that are to norm continuous are exactly those in ; and a bornology on such that the elements of which map the unit ball to an element of , equivalently those members of that are norm to bounded, are exactly those in . This is achieved via analogues of the notions of injectivity and surjectivity in the theory of operator ideals on Banach spaces.     

Enantioselective partial reduction of 2,5-disubstituted pyrroles via a chiral protonation approach

[reaction: see text] The partial reduction of 2,5-pyrrole diester 1 followed by enantioselective protonation in situ to furnish synthetically useful building blocks is described. An enantiomeric excess of up to 74% was achieved using (-)-ephedrine and related analogues as chiral proton sources. The pyrroline product obtained could be recrystallized to give enantiomerically pure material.     

Synthesis of enantiopure dihydropyranones: aldol-based ring expansion of dihydrofurans

[reaction: see text] The stereoselective Birch reduction of 3-methyl-2-furoic acids using a readily available chiral auxilairy is described; by coupling this process to an oxidative cleavage/aldol ring closure sequence we were able to produce highly functionalized and enantiopure dihydropyranones in high yield. This sequence has ample flexibility built into it, either by the use of different electrophiles during reductive alkylation or by subsequent derivatization of the dihydropyranone after ring expansion.     

The reaction of acyl peroxides with 2,2,6,6-tetramethylpiperidinyl-1-oxy

Benzoyl ana lauroyl peroxides undergo induced decomposition by 2,2,6,6-tetramethylpiperidinyl-1-oxy to form acyloxy radicals and carboxylic acid in equimolar amounts. Formation of the carboxylic acid does not involve free acyloxy radicals.