Investigation of the role of neutron transfer in the fusion of 32,34S with 197Au,208Pb using quasi-elastic scattering

Excitation functions for quasi-elastic scattering have been measured at backward angles for the systems 32,34S+197Au and 32,34S+208Pb for energies spanning the Coulomb barrier. Representative distributions, sensitive to the low energy part of the fusion barrier distribution, have been extracted from the data. For the fusion reactions of 32,34S with 197Au couplings related to the nuclear structure of 197Au appear to be dominant in shaping the low energy part of the barrier distibution. For the system 32S+208Pb the barrier distribution is broader and extends further to lower energies, than in the case of 34S+208Pb. This is consistent with the interpretation that the neutron pick-up channels are energetically more favoured in the 32S induced reaction and therefore couple more strongly to the relative motion. It may also be due to the increased collectivity of 32S, when compared with 34S.Comment: 11 pages, 5 figure

On-line (HPLC-NMR) and off-line phytochemical profiling of the Australian plant, Lasiopetalum macrophyllum

On-line (HPLC-NMR) and off-line (HPLC, NMR and MS) methodologies were used to profile the constituents present in the crude extract of Lasiopetalum macrophyllum. On-flow and stop-flow HPLC-NMR supported the presence of trans-tiliroside and permitted partial identification of cis-tiliroside and 4'-methoxy-trans-tiliroside. Off-line isolation led to the unequivocal identification of four flavanoid glycosides including a new structural derivative, 4'-methoxy-cis-tiliroside. This is the first report of flavonoid glycosides occurring in this plant genus. In addition, a number of structure revisions have been proposed for previously reported flavonoid glycosides that were incorrectly assigned

Creativity, collaboration and development in Jeremy Thurlow's Ouija for Peter Sheppard Skaerved

This paper documents and analyses a creative collaboration between the Composer Jeremy Thurlow and the violinist Peter Sheppard Skærved in the production of Ouija, a work for solo violin and laptop computer. The paper situates the account of this creative process within recent literature on distributed and collaborative creativity, and focuses on three aspects of the project: verbal interaction between the two musicians, analysed in terms of ‘creative-talk’ and ‘face-talk’, and the relationship between immediate and more contextual concerns (‘inside/outside the room’); a quantitative analysis of changes in the musical material, focusing on timing; and a qualitative analysis of the role of the violinist’s embodied and instrumental engagement with the music. The paper discusses the findings in relation to forward-oriented (process) and backward-oriented (product) conceptions of creativity, the operation of different social components in creative collaboration, and the relationship between craft, history and embodiment

Disentangling conical intersection and coherent molecular dynamics in methyl bromide with attosecond transient absorption spectroscopy

Attosecond probing of core-level electronic transitions provides a sensitive tool for studying valence molecular dynamics with atomic, state, and charge specificity. In this report, we employ attosecond transient absorption spectroscopy to follow the valence dynamics of strong-field initiated processes in methyl bromide. By probing the 3d core-to-valence transition, we resolve the strong field excitation and ensuing fragmentation of the neutral σ* excited states of methyl bromide. The results provide a clear signature of the non-adiabatic passage of the excited state wavepacket through a conical intersection. We additionally observe competing, strong field initiated processes arising in both the ground state and ionized molecule corresponding to vibrational and spin-orbit motion, respectively. The demonstrated ability to resolve simultaneous dynamics with few-femtosecond resolution presents a clear path forward in the implementation of attosecond XUV spectroscopy as a general tool for probing competing and complex molecular phenomena with unmatched temporal resolution

Marine and terrestrial natural products discovery

This thesis describes the natural product study of three Australian plants and two southern Australian marine algae. The application of the hyphenated spectroscopic technique, HPLC-NMR, was successfully implemented in the partial identification or as a dereplication of the secondary metabolites present in each of the studied organisms. HPLC-NMR was particularly suited to the identification of an unstable new secondary metabolite identified from one of the marine organisms. In total this thesis resulted in the isolation and structural elucidation of five new secondary metabolites, one new X-ray crystal structure of a previously reported compound and twenty-two known secondary metabolites, of which five structural and/or chemical shift re-assignments were deduced. On-line (HPLC-NMR) and off-line (HPLC, NMR and MS) profiling of the Australian plant Lasiopetalum macrophyllum allowed for the identification of four flavonoid glycosides, including a new structural analogue. This study represented the first report of flavonoid glycosides occurring within this plant genus. The study of the Australian plant Haemodorum simulans was carried out using a combination of on-line (HPLC-NMR) and off-line (HPLC, NMR, MS) methodologies. This resulted in the isolation of two new phenylphenalenones from the bulbs of the plant, along with the first report of an oxabenzochrysenone glycoside, which was isolated from the aerial parts of the plant. Four previously reported secondary metabolites including two phenylphenalenones and two oxabenzochrysenones were also isolated, with the first X-ray structure of one of the phenylphenalenones also obtained. The HPLC-NMR chemical profiling study of the crude extract derived from the bulbs of the Australian carnivorous plant Drosera erythrohiza subspecies magna resulted in the partial identification of two naphthoquinones, as well as a mixture of two naphthoquinone glycosides. Subsequent off-line isolation (semi-preparative HPLC) of these secondary metabolites, followed by NMR spectroscopic and mass spectrometric analyses of the crude extract from the bulbs resulted in the identification of two naphthoquinones and two naphthoquinone glycosides. In addition to this off-line methodologies were utilised to isolate a further naphthoquinone from the aerial parts of this plant. Biological activity studies concluded that one of the naphthoquinones possessed potent broad spectrum activity. The study of the Australian marine red alga Plocamium angustum led to the identification of one new and one previously reported secondary metabolites. This led to the structural re-assignment of the previously reported secondary metabolite plocamenone. This compound displayed potent broad spectrum biological activity. An on-line chemical profiling/dereplication study of the Australian brown alga Cystophora torulosa, using HPLC-NMR in combination with the use of the MarinLit database led to the identification of two classes of secondary metabolites, resorcinol derivatives and polyenes. In total seven secondary metabolites were identified by on-flow HPLC-NMR analysis, including five resorcinol derivatives and two polyenes. Off-line small-scale analytical HPLC collection and subsequent ESI-MS or GC-MS analyses of the crude extract allowed for the identification of a total of nine secondary metabolites including seven resorcinol derivatives and two polyenes with the aid of the MarinLit database

Dynamic control of selectivity in the ubiquitination pathway revealed by an ASP to GLU substitution in an intra-molecular salt-bridge network

Ubiquitination relies on a subtle balance between selectivity and promiscuity achieved through specific interactions between ubiquitin-conjugating enzymes (E2s) and ubiquitin ligases (E3s). Here, we report how a single aspartic to glutamic acid substitution acts as a dynamic switch to tip the selectivity balance of human E2s for interaction toward E3 RING-finger domains. By combining molecular dynamic simulations, experimental yeast-two-hybrid screen of E2-E3 (RING) interactions and mutagenesis, we reveal how the dynamics of an internal salt-bridge network at the rim of the E2-E3 interaction surface controls the balance between an “open”, binding competent, and a “closed”, binding incompetent state. The molecular dynamic simulations shed light on the fine mechanism of this molecular switch and allowed us to identify its components, namely an aspartate/glutamate pair, a lysine acting as the central switch and a remote aspartate. Perturbations of single residues in this network, both inside and outside the interaction surface, are sufficient to switch the global E2 interaction selectivity as demonstrated experimentally. Taken together, our results indicate a new mechanism to control E2-E3 interaction selectivity at an atomic level, highlighting how minimal changes in amino acid side-chain affecting the dynamics of intramolecular salt-bridges can be crucial for protein-protein interactions. These findings indicate that the widely accepted sequence-structure-function paradigm should be extended to sequence-structure-dynamics-function relationship and open new possibilities for control and fine-tuning of protein interaction selectivity

Ethical Issues in Research and Development of Epigenome-wide Technologies

To date, few scholarly discussions on ethical implications of epigenetics and epigenomics technologies have focused on the current phase of research and development, in which researchers are confronted with real and practical ethical dilemmas. In this article, a responsible research and innovation approach, using interviews and an expert meeting, is applied to a case of epigenomic test development for cervical cancer screening. This article provides an overview of ethical issues presently facing epigenomics researchers and test developers, and discusses 3 sets of issues in depth: (1) informed consent; (2) communication with donors and/or research participants, and (3) privacy and publication of data and research results. Although these issues are familiar to research ethics, some aspects are new and most require reinterpretation in the context of epigenomics technologies

Regulation of Medical Emergency Research legal policy and medical practice

This thesis focuses on the medical practice and legal regulation of medical scientific research with humans in medical emergency situations