46 research outputs found
Investigation into the reactivity of pentafluorophenyl vinylsulfonate in the formation of functionalized sulfonamides of biological importance.
Sulfonamides constitute a vital and diverse class of therapeutic agents hence the development of convenient and straightforward synthetic routes to such species is a valuable endeavour. This thesis describes an exploration into the reactivity of the novel bifunctional acceptor pentafluorophenyl vinylsulfonate in the formation of biologically interesting sulfonamide species. A variety of transformations were carried out effectively at the electron-deficient olefinic portion of pentafluorophenyl vinylsulfonate to provide functionalized pentafluorophenyl esters. Subsequent displacement of the pentafluorophenyl moiety via an established aminolysis procedure then delivered the corresponding sulfonamide products. During the course of this investigation, it was established that both radical and cycloaddition routes were successful in furnishing desirable compounds. It was found that intermolecular radical addition of alkyl halides occurred readily and permitted the formation of a number of sulfonamide addition products. In addition, Diels-Alder cycloaddition with carbocyclic dienes and furan formed stable exo-bicyclic sulfonamides. Notably, 1,3-dipolar cycloaddition with a diverse library of A/-methyl-nitrones gave the corresponding isoxazolidine species with unprecedented regio- and stereoselectivity. Subsequent aminolysis delivered functionalized heterocyclic sulfonamides with potential biological importance
Instability, Intermixing and Electronic Structure at the Epitaxial LaAlO3/SrTiO3(001) Heterojunction
The question of stability against diffusional mixing at the prototypical
LaAlO3/SrTiO3(001) interface is explored using a multi-faceted experimental and
theoretical approach. We combine analytical methods with a range of
sensitivities to elemental concentrations and spatial separations to
investigate interfaces grown using on-axis pulsed laser deposition. We also
employ computational modeling based on the density function theory as well as
classical force fields to explore the energetic stability of a wide variety of
intermixed atomic configurations relative to the idealized, atomically abrupt
model. Statistical analysis of the calculated energies for the various
configurations is used to elucidate the relative thermodynamic stability of
intermixed and abrupt configurations. We find that on both experimental and
theoretical fronts, the tendency toward intermixing is very strong. We have
also measured and calculated key electronic properties such as the presence of
electric fields and the value of the valence band discontinuity at the
interface. We find no measurable electric field in either the LaAlO3 or SrTiO3,
and that the valence band offset is near zero, partitioning the band
discontinuity almost entirely to the conduction band edge. Moreover, we find
that it is not possible to account for these electronic properties
theoretically without including extensive intermixing in our physical model of
the interface. The atomic configurations which give the greatest electrostatic
stability are those that eliminate the interface dipole by intermixing, calling
into question the conventional explanation for conductivity at this interface -
electronic reconstruction. Rather, evidence is presented for La indiffusion and
doping of the SrTiO3 below the interface as being the cause of the observed
conductivity
The impact of growth promoters on muscle growth and the potential consequences for meat quality
To meet the demands of increased global meat consumption, animal production systems will have to become more efficient, or at least maintain the current efficiency utilizing feed ingredients that are not also used for human consumption. Use of growth promoters is a potential option for increasing production animal feed efficiency and increased muscle growth. The objective of this manuscript is to describe the mechanisms by which the growth promoters, beta-adrenergic agonists and growth hormone, mediate their effects, with specific consideration of the aspects which have implications for meat quality.The work described in this manuscript was supported by a BBSRC LINK Zoetis grant, number BB/J005320/1, as well as a BBSRC CASE PhD studentship awarded to David Brown and Krystal Hemmings and a PhD scholarship awarded to Molebeledi HD Mareko by the Botswana College of Agricultur
Stirring the Lions: Strategy and Tactics in Global Higher Education
Network- Globalisation and Europeanisation in Education (GENIE); more recently, she has been leading a network of scholars focused on globalisation and education throug