Hydrazine network on Cu(111) surface: A Density Functional Theory approach

We have used first-principles calculations, including a correction for the dispersive forces (DFT-D2), to investigate the arrangement of hydrazine (N2H4) molecules upon adsorption on the Cu(111) surface, showing that surface–molecule interactions affect the process most. Our calculations provide insight into the interplay between lateral adsorbate–adsorbate and vertical adsorbate–substrate interactions. We found that the main contributors to the assembly of the hydrazine layers are the binding interactions between the adsorbates and the substrate. The dispersion forces are predominant in both vertical and lateral interactions, whereas hydrogen-bonding is least important and organisation of the N2H4 monolayers is therefore primarily due to the long-range interactions. Optimised geometries for several hydrazine conformations were found to be coverage-dependent. The electronic properties such as charge density and density of states have been calculated for different hydrazine coverages, and indicated that no charge transfer occurs between molecules. Scanning tunnelling microscopy images were simulated, where the observed protrusions arise from the trans conformers. We also found that the effect of hydrazine adsorption on the Cu(111) surface energy is negligible and further investigation of other Cu facets is needed to determine the N2H4 effect on the nanoparticles' morphology. Finally, we have simulated the temperature programmed desorption of different coverages of hydrazine from the Cu(111) resulting in desorption peaks between 150 and 200 K

The evolution of tree nursery offerings in Los Angeles County over the last 110 years

Interest in urban vegetation has increased dramatically. Urban trees are an important aspect of the urban environment but there is little known about the potential sources of those trees, change in tree species diversity over time and the factors leading to the contemporary floristic composition in cities. We investigate tree nursery offerings in Los Angeles County over the past 110 years through the use of here-to-fore unexplored nursery catalogs to determine the diversity of trees that have been commercially available over time. Tree species information was collected spanning a 110-year study period and analyzed the data for four time periods (1900-1929, 1930-1959, 1960-1989, and 1990-2011). We found the number of genera and tree species offered significantly increased in the past 20 years (1990-2011). The numbers of non-native trees, angiosperms, and deciduous species all significantly increased with but no changes were observed in the numbers of native, evergreen, or gymnosperm species offered over this time period. The largest numbers of palm species were offered in 1900-1929. Overall there were 562 unique species offered belonging to 201 different genera in the 120-year study period, 48 species were California native trees and 514 of these were non-native species indicating that perhaps Los Angeles has one of the most diverse number of tree species offered for sale by the nursery industry. © 2013 Elsevier B.V

Threats of future climate change and land use to vulnerable tree species native to Southern California

Climate and land-use changes are expected to drive high rates of environmental change and biodiversity loss in Mediterranean ecosystems this century. This paper compares the relative future impacts of land use and climate change on two vulnerable tree species native to Southern California (Juglans californica and Quercus engelmannii) using species distribution models. Under the Intergovernmental Panel for Climate Change's A1B future scenario, high levels of both projected land use and climate change could drive considerable habitat losses on these two already heavily-impacted tree species. Under scenarios of no dispersal, projected climate change poses a greater habitat loss threat relative to projected land use for both species. Assuming unlimited dispersal, climate-driven habitat gains could offset some of the losses due to both drivers, especially in J. californica which could experience net habitat gains under combined impacts of both climate change and land use. Quercus engelmannii, in contrast, could experience net habitat losses under combined impacts, even under best-case unlimited dispersal scenarios. Similarly, projected losses and gains in protected habitat are highly sensitive to dispersal scenario, with anywhere from > 60% loss in protected habitat (no dispersal) to > 170% gain in protected habitat (unlimited dispersal). The findings underscore the importance of dispersal in moderating future habitat loss for vulnerable species

P2X receptors: epithelial ion channels and regulators of salt and water transport.

When the results from electrophysiological studies of renal epithelial cells are combined with data from in vivo tubule microperfusion experiments and immunohistochemical surveys of the nephron, the accumulated evidence suggests that ATP-gated ion channels, P2X receptors, play a specialized role in the regulation of ion and water movement across the renal tubule and are integral to electrolyte and fluid homeostasis. In this short review, we discuss the concept of P2X receptors as regulators of salt and water salvage pathways, as well as acknowledging their accepted role as ATP-gated ion channels

Shotguns vs Lasers: Identifying barriers and facilitators to scaling-up plant molecular farming for high-value health products.

Plant molecular farming (PMF) is a convenient and cost-effective way to produce high-value recombinant proteins that can be used in the production of a range of health products, from pharmaceutical therapeutics to cosmetic products. New plant breeding techniques (NPBTs) provide a means to enhance PMF systems more quickly and with greater precision than ever before. However, the feasibility, regulatory standing and social acceptability of both PMF and NPBTs are in question. This paper explores the perceptions of key stakeholders on two European Union (EU) Horizon 2020 programmes-Pharma-Factory and Newcotiana-towards the barriers and facilitators of PMF and NPBTs in Europe. One-on-one qualitative interviews were undertaken with N = 20 individuals involved in one or both of the two projects at 16 institutions in seven countries (Belgium, France, Germany, Italy, Israel, Spain and the UK). The findings indicate that the current EU regulatory environment and the perception of the public towards biotechnology are seen as the main barriers to scaling-up PMF and NPBTs. Competition from existing systems and the lack of plant-specific regulations likewise present challenges for PMF developing beyond its current niche. However, respondents felt that the communication of the benefits and purpose of NPBT PMF could provide a platform for improving the social acceptance of genetic modification. The importance of the media in this process was highlighted. This article also uses the multi-level perspective to explore the ways in which NPBTs are being legitimated by interested parties and the systemic factors that have shaped and are continuing to shape the development of PMF in Europe

Thermal simulation outputs: exploring the concept of patterns in design decision-making

This paper describes the ongoing development of a building performance simulation (BPS) knowledge management scheme for design decision-making. This knowledge management scheme is developed with reference to the patterns of Christopher Alexander and colleagues, which describe commonly recurring abstract problems in architectural design together with successful abstract solutions. As such they form a ‘repository of knowledge’ on architectural design. Patterns have been used in other fields such as software engineering where they also aim at capturing expert knowledge, and their potential to do the same for BPS is explored here. Decision support using simulation is introduced and the concept of patterns described. A pattern structure is developed and some examples given. Interviews with architectural practices investigated whether patterns could support design processes, and the further development of the concept is discussed

Flowing Between Fermionic Fixed Points

We study holographic Wilsonian renormalization group flows for bulk spinor fields in AdS. We use this to compute the all-loop beta function for fermionic double trace operators in the dual conformal field theory.Comment: 21 pages. V2: Acknowledgement added; v3: Typo correcte

Survey of H-alpha emission from thirty nearby dwarf galaxies

Measurements of the H-alpha flux from 30 neighboring dwarf galaxies are presented. After correction for absorption, these fluxes are used to estimate the star formation rate (SFR). The SFR for 18 of the galaxies according to the H-alpha emission are compared with estimates of the SFR from FUV magnitudes obtained with the GALEX telescope. These are in good agreement over the range log[SFR] = [-3,0]M sun/yr.Comment: 18 pages, 10 figures, 3 table