Nesting habits of some East African birds

Volume: II

A proof-of-concept Bitter-like HTS electromagnet fabricated from a silver-infiltrated (RE)BCO ceramic bulk

A novel concept for a compact high-field magnet coil is introduced. This is based on stacking slit annular discs cut from bulk rare-earth barium cuprate ((RE)BCO) ceramic in a Bitter-like architecture. Finite-element modelling shows that a small 20 turn stack (with a total coil volume of <20 cm3) is capable of generating a central bore magnetic field of >2 T at 77 K and >20 T at 30 K. Unlike resistive Bitter magnets, the high-temperature superconducting (HTS) Bitter stack exhibits significant non-linear field behaviour during current ramping, caused by current filling proceeding from the inner radius outwards in each HTS layer. Practical proof-of-concept for this architecture was then demonstrated through fabricating an uninsulated four-turn prototype coil stack and operating this at 77 K. A maximum central field of 0.382 T was measured at 1.2 kA, with an accompanying 6.1 W of internal heat dissipation within the coil. Strong magnetic hysteresis behaviour was observed within the prototype coil, with ≈30% of the maximum central field still remaining trapped 45 min after the current had been removed. The coil was thermally stable during a 15 min hold at 1 kA, and survived thermal cycling to room temperature without noticeable deterioration in performance. A final test-to-destruction of the coil showed that the limiting weak point in the stack was growth-sector boundaries present in the original (RE)BCO bulk

Timescale of Stellar Feedback-Driven Turbulence in the ISM: A Deep Dive into UGC 4305

Understanding the interplay of stellar feedback and turbulence in the interstellar medium (ISM) is essential to modeling the evolution of galaxies. To determine the timescales over which stellar feedback drives turbulence in the ISM, we performed a spatially resolved, multi-wavelength study of the nearby star-forming dwarf galaxy UGC 4305 (aka Holmberg II). As indicators of turbulence on local scales (400 pc), we utilized ionized gas velocity dispersion derived from IFU H$\alpha$ observations and atomic gas velocity dispersion and energy surface densities derived from HI synthesis observations with the Very Large Array. These indicators of turbulence were tested against star formation histories over the past 560 Myr derived from Color-Magnitude Diagrams (CMD) using Spearman's rank correlation coefficient. The strongest correlation identified at the 400 pc scale is between measures of HI turbulence and star formation 70-140 Myr ago. We repeated our analysis of UGC 4305's current turbulence and past star formation activity on multiple physical scales ($\sim$560, and 800 pc) to determine if there are indications of changes in the correlation timescale with changes to the physical scale. No notable correlations were found at larger physical scales emphasizing the importance of analyzing star formation driven turbulence as a local phenomenon.Comment: 17 pages, 9 figure, accepted to A

Facile access to a heterocyclic, sp3-rich chemical scaffold via a tandem condensation/intramolecular nitrone–alkene [3+2] cycloaddition strategy

A heterocyclic, sp3-rich chemical scaffold was synthesised in just 6 steps via a highly regio- and diastereo-selective tandem nitrone formation/intramolecular nitrone–alkene [3+2] cycloaddition reaction. A library of 543 lead-like compounds based on the scaffold core has been produced

SGC - Structural Biology and Human Health: A New Approach to Publishing Structural Biology Results

The Structural Genomics Consortium (SGC) is a not-for-profit, public-private partnership established to deliver novel structural biology knowledge on proteins of medical relevance and place this information into the public domain without restriction, spearheading the concept of "Open-Source Science" to enable drug discovery. The SGC is a major provider of structural information focussed on proteins related to human health, contributing 20.5% of novel structures released by the PDB in 2008. In this article we describe the PLoS ONE Collection entitled 'Structural Biology and Human Health: Medically Relevant Proteins from the SGC'. This Collection contains a series of articles documenting many of the novel protein structures determined by the SGC and work to further characterise their function. Each article in this Collection can be read in an enhanced version where we have integrated our interactive and intuitive 3D visualisation platform, known as iSee. This publishing platform enables the communication of complex structural biology and related data to a wide audience of non-structural biologists. With the use of iSee as the first example of an interactive and intuitive 3D document publication method as part of PLoS ONE, we are pushing the boundaries of structural biology data delivery and peer-review. Our strong desire is that this step forward will encourage others to consider the need for publication of three dimensional and associated data in a similar manner. © 2009 Lee et al

Real-time observation of multiexcitonic states in ultrafast singlet fission using coherent 2D electronic spectroscopy.

Singlet fission is the spin-allowed conversion of a spin-singlet exciton into a pair of spin-triplet excitons residing on neighbouring molecules. To rationalize this phenomenon, a multiexcitonic spin-zero triplet-pair state has been hypothesized as an intermediate in singlet fission. However, the nature of the intermediate states and the underlying mechanism of ultrafast fission have not been elucidated experimentally. Here, we study a series of pentacene derivatives using ultrafast two-dimensional electronic spectroscopy and unravel the origin of the states involved in fission. Our data reveal the crucial role of vibrational degrees of freedom coupled to electronic excitations that facilitate the mixing of multiexcitonic states with singlet excitons. The resulting manifold of vibronic states drives sub-100 fs fission with unity efficiency. Our results provide a framework for understanding singlet fission and show how the formation of vibronic manifolds with a high density of states facilitates fast and efficient electronic processes in molecular systems.This is the author accepted manuscript. The final version is available from NPG via http://dx.doi.org/10.1038/nchem.237

Comparative Analysis of the Heptahelical Transmembrane Bundles of G Protein-Coupled Receptors

Background: G protein-coupled receptors represent a large family of eukaryotic membrane proteins, and are involved in almost all physiological processes in humans. Recent advances in the crystallographic study of these receptors enable a detailed comparative analysis of the commonly shared heptahelical transmembrane bundle. Systematic comparison of the bundles from a variety of receptors is indispensable for understanding not only of the structural diversification optimized for the binding of respective ligands but also of the structural conservation required for the common mechanism of activation accompanying the interaction changes among the seven helices. Methodology/Principal Findings: We have examined the bundles of 94 polypeptide chains from almost all available structures of 11 receptors, which we classified into either inactivated chain or activated chain, based on the type of bound ligand. For the inactivated chains, superposition of 200 residue bundles by secondary structure matching demonstrated that the bound ligands share a laterally limited cavity in the extracellular section of the bundle. Furthermore, a distinct feature was found for helix III of bovine rhodopsin, which might have evolved to lower its activity in the presence of 11-cis-retinal, to a level that other receptors could hardly achieve with any currently available ligands. Conclusions/Significance: Systematic analysis described here would be valuable for understanding of the rearrangement o

Optimisation of pH of cadmium chloride post-growth-treatment in processing CDS/CDTE based thin film solar cells

The role of Chlorine-based activation in the production of high quality CdS/CdTe photovoltaic have been well discussed and explored with an overlook of the effect of Cadmium chloride (CdCl2) post-growth treatment acidity on the property of the fabricated devices. This work focuses on the optimisation of CdCl2 post-growth treatment pH as it affects both the material and fabricated device properties of all-electrodeposited multilayer glass/FTO/n-CdS/n-CdTe/p-CdTe configuration. CdCl2 treatments with acidity ranging from pH1 to pH4 were explored. The properties of the ensued CdTe layer were explored using optical, morphological, compositional structural and electrical property analysis, while, the effect on fabricated multilayer glass/FTO/n-CdS/n-CdTe/p-CdTe configuration were also explored using both I-V and C-V measurements. Highest improvements in the optical, morphological, compositional and structural were observed at pH2 CdCl2 post-growth treatment with an improvement in absorption edge, grain size, crystallinity and crystallite size. Conductivity type conversions from n-CdTe to p-CdTe, increase in pin-hole density and collapse of the absorption edge were observed after pH1 CdCl2 treatment. The highest fabricated solar cell efficiency of 13% was achieved using pH2 CdCl2 treatment as compared to other pH values explored