Evolution of the dark matter distribution at the galactic center

Annihilation radiation from neutralino dark matter at the Galactic center (GC) would be greatly enhanced if the dark matter were strongly clustered around the supermassive black hole (SBH). The existence of a dark matter "spike" is made plausible by the observed, steeply rising stellar density near the GC SBH. Here the time-dependent equations describing gravitational interaction of the dark matter with the stars are solved. Scattering of dark matter particles by stars would substantially lower the dark matter density near the GC SBH over 10 Gyr, due both to kinetic heating and to capture of dark matter particles by the SBH. This evolution implies a decrease by several orders of magnitude in the observable flux of annihilation products compared with models that associate a steep, dark matter spike with the SBH.     

Chloroplatinic acid catalyzed additions of silanes to isoprene

The chloroplatinic acid catalyzed hydrosilylation of isoprene with trichlorodichloromethyl-, and trimethylsilane has been reinvestigated with the purpose of establishing the mode of addition to the substrate. This was accomplished by identifying the structures of the $\text{1}\text{1}$ adducts, their methylated derivatives and the saturated analogs of the latter. Trichlorosilane added 1,4 to the less hindered side of isoprene; dichloromethylsilane added both 1,2 and 1,4 to the less hindered side and trimethylsilane added 1,2 and 1,4 to both sides of isoprene. These results are contrary to those previously reported in the literature.     

The clerodane ring system: investigating the viability of a direct Diels-Alder approach

A direct synthetic approach to the spiro-γ-lactone clerodane ring system has been investigated. This work builds on that of Jung and highlights the inherent difficulties associated with the otherwise obvious Diels-Alder approach.     

Screening a fragment cocktail library using ultrafiltration

Ultrafiltration provides a generic method to discover ligands for protein drug targets with millimolar to micromolar K(d), the typical range of fragment-based drug discovery. This method was tailored to a 96-well format, and cocktails of fragment-sized molecules, with molecular masses between 150 and 300 Da, were screened against medical structural genomics target proteins. The validity of the method was confirmed through competitive binding assays in the presence of ligands known to bind the target proteins.