A next-generation liquid xenon observatory for dark matter and neutrino physics

The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector

A systematic study of the solid state and solution phase conformational preferences of beta-peptides derived from C(3)-alkyl substituted transpentacin derivatives

The solid state and solution phase conformational preferences of a homologous series of β-peptides derived from a range of 2-amino-3-alkylcyclopentanecarboxylic acid residues have been investigated using a variety of spectroscopic and crystallographic techniques. These studies indicate that C(3)-alkyl substitution trans to the amino group on the cyclopentane backbone is tolerated by the established 12-helix secondary structural preference of the parent pentamer and hexamer derived from 2-aminocyclopentanecarboxylic acid (transpentacin) residues in both the solid state and solution phase. Evidence for the alternative turn type conformation identified for the C(3)-unsubstituted tetramer was not observed in the C(3)-alkyl substituted derivatives, consistent with the alkyl substituent anti to the amino functionality destabilising this motif. These results suggest that oligomers based around the transpentacin scaffold may be amenable to further elaboration at C(3) anti to the amino group with retention of the secondary structure. © 2011 Elsevier Ltd. All rights reserved

A systematic study of the solid state and solution phase conformational preferences of beta-peptides derived from transpentacin

The solid state and solution phase conformational preferences of a homologous series of β-peptides derived from (S,S)-2- aminocyclopentanecarboxylic acid (transpentacin) have been investigated using a variety of spectroscopic and crystallographic techniques. These studies indicate that the hexamer and pentamer persist as a 12-helix in both the solid state and solution phase. Although the conformational traits of a 12-helix are exhibited by oligomers with as few as three residues in the solid state, in solution the trimer exists as an equilibrium of many alternative conformers whilst the tetramer has been shown to predominantly exist in either a 12-helix or a turn-type conformation. © 2010 Elsevier Ltd. All rights reserved

Physical, chemical and biological processes in Lake Vostok and other Antarctic subglacial lakes

Over 70 lakes have now been identi®ed beneath the Antarctic ice sheet. Although water from none of the lakes has been sampled directly, analysis of lake ice frozen (accreted) to the underside of the ice sheet above Lake Vostok, the largest of these lakes, has allowed inferences to be made on lake water chemistry and has revealed small quantities of microbes. These ®ndings suggest that Lake Vostok is an extreme, yet viable, environment for life. All subglacial lakes are subject to high pressure (,350 atmospheres), low temperatures (about -3 8C) and permanent darkness. Any microbes present must therefore use chemical sources to power biological processes. Importantly, dissolved oxygen is available at least at the lake surface, from equilibration with air hydrates released from melting basal glacier ice. Microbes found in Lake Vostok's accreted ice are relatively modern, but the probability of ancient lake-¯oor sediments leads to a possibility of a very old biota at the base of subglacial lakes