6,041 research outputs found

    The Baylis-Hillman entrée to heterocyclic systems — the Rhodes contribution

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    This review focuses on applications of the Baylis-Hillman reaction in the synthesis of various heterocyclic products, which include indolizines, chromenes, thiochromenes, coumarins and quinolines. Attention is also given to the mechanistic implications and the elaboration of various products to afford compounds with medicinal potential

    Designer ligands : the search for metal ion selectivity

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    The paper reviews research conducted at Rhodes University towards the development of metal-selective ligands. The research has focused on the rational design, synthesis and evaluation of novel ligands for use in the formation of copper complexes as biomimetic models of the metalloenzyme, tyrosinase, and for the selective extraction of silver, nickel and platinum group metal ions in the presence of contaminating metal ions. Attention has also been given to the development of efficient, metal-selective molecular imprinted polymers

    ""Of molecules and men"" : inaugural lecture delivered at Rhodes University

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    Inaugural lecture delivered at Rhodes UniversityRhodes University Libraries (Digitisation

    Correlation between acoustic scatterers and temperature gradient

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    A correlation has been found between acoustic scattering intensity at 87.5 kHz and smallscale vertical temperature gradients. Prior to the rise of the Sound Scattering Layer (SSL), there was a positive correlation, which persisted for about an hour after the upward evening SSL migration. After this time a diffuse downward migration was observed until the correlation was significantly negative. Possible rationales for this behavior are suggested

    Formation of 3,3,4-trimethyl-1,7-dibromonorbornane-2-one: a spectroscopic and computational Study

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    The structure and origin of the major by-product in the synthesis of 8-bromocamphor from (+)-3,3,8-tribromocamphor has been confirmed using NMR, coset and single crystal X-ray analysis and DFT-level computational techniques

    Modelling light scattering by absorbing smooth and slightly rough facetted particles

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    A method for approximating light scattering properties of strongly absorbing facetted particles which are large compared to the wavelength is presented. It consists in adding the approximated external diffraction and reflection far fields and is demonstrated for a smooth hexagonal prism. This computationally fast method is extended towards prisms with slightly rough surfaces by introducing a surface scaling factor in order to account for edge effects on subfacets forming the rough surface. These effects become more pronounced with decreasing subfacet dimension to wavelength ratio. Azimuthally resolved light scattering patterns, phase functions and degree of linear polarisation obtained by this method and by the Discrete Dipole Approximation are compared for hexagonal prisms with smooth and slightly rough surfaces, respectively.Peer reviewedSubmitted Versio

    Effect of Death Jumps and Back Squats on Eliciting Postactivation Potentiation for a 40-meter Sprint

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    Please refer to the pdf version of the abstract located adjacent to the title

    Incidence of rough and irregular atmospheric ice particles from Small Ice Detector 3 measurements

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    NERC, NE/E011225/1 © Author(s) 2013. This work is distributed under the Creative Commons Attribution 3.0 LicenseThe knowledge of properties of ice crystals such as size, shape, concavity and roughness is critical in the context of radiative properties of ice and mixed phase clouds. Limitations of current cloud probes to measure these properties can be circumvented by acquiring two-dimensional light scattering patterns instead of particle images. Such patterns were obtained in situ for the first time using the Small Ice Detector 3 (SID-3) probe during several flights in a variety of mid-latitude mixed phase and cirrus clouds. The patterns are analyzed using several measures of pattern texture, selected to reveal the magnitude of particle roughness or complexity. The retrieved roughness is compared to values obtained from a range of well-characterized test particles in the laboratory. It is found that typical in situ roughness corresponds to that found in the rougher subset of the test particles, and sometimes even extends beyond the most extreme values found in the laboratory. In this study we do not differentiate between small-scale, fine surface roughness and large-scale crystal complexity. Instead, we argue that both can have similar manifestations in terms of light scattering properties and also similar causes. Overall, the in situ data is consistent with ice particles with highly irregular or rough surfaces being dominant. Similar magnitudes of roughness were found in growth and sublimation zones of cirrus. The roughness was found to be negatively correlated with the halo ratio, but not with other thermodynamic or microphysical properties found in situ. Slightly higher roughness was observed in cirrus forming in clean oceanic airmasses than in a continental, polluted one. Overall, the roughness and complexity is expected to lead to increased shortwave cloud reflectivity, in comparison with cirrus composed of more regular, smooth ice crystal shapes. These findings put into question suggestions that climate could be modified through aerosol seeding to reduce cirrus cover and optical depth, as the seeding may result in decreased shortwave reflectivity.Peer reviewe
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