1,595 research outputs found
Bis(2-phenyl-4,6-di-2-pyridyl-1,3,5-triazine-κ3 N 4,N 5,N 6)ruthenium(II) bis(hexafluoridophosphate)
The asymmetric unit of the title compound, [Ru(C19H13N5)2](PF6)2, consists of an RuII complex cation and two hexafluoridophosphate anions. The RuII atom is coordinated by three N atoms from the two outer pyridine and the central triazine rings of each of two tridentate ligands in a distorted octahedral environment. The ligands are approximately orthogonal to one another, with a dihedral angle of 88.34 (2)° between planes through the three six-membered rings of the two ligands. The pendant phenyl substituents are almost coplanar with the triazine rings to which they are bound, with dihedral angles of 5.41 (9) and 14.90 (10)°. This is reflected in the previously reported photophysical results with an increased lifetime of the triplet metal to ligand charge transfer (3MLCT) excited state [Fang, Taylor, Hanan, Loiseau, Passalacqua, Campagna, Nierengarten & Van Dorsselaer (2002). J. Am. Chem. Soc.
124, 7912–7913]
Diffuse flow environments within basalt- and sediment-based hydrothermal vent ecosystems harbor specialized microbial communities
Hydrothermal vents differ both in surface input and subsurface geochemistry. The effects of these differences on their microbial communities are not clear. Here, we investigated both alpha and beta diversity of diffuse flow-associated microbial communities emanating from vents at a basalt-based hydrothermal system along the East Pacific Rise (EPR) and a sediment-based hydrothermal system, Guaymas Basin. Both Bacteria and Archaea were targeted using high throughput 16S rRNA gene pyrosequencing analyses. A unique aspect of this study was the use of a universal set of 16S rRNA gene primers to characterize total and diffuse flow-specific microbial communities from varied deep-sea hydrothermal environments. Both surrounding seawater and diffuse flow water samples contained large numbers of Marine Group I (MGI) Thaumarchaea and Gammaproteobacteria taxa previously observed in deep-sea systems. However, these taxa were geographically distinct and segregated according to type of spreading center. Diffuse flow microbial community profiles were highly differentiated. In particular, EPR dominant diffuse flow taxa were most closely associated with chemolithoautotrophs, and off axis water was dominated by heterotrophic-related taxa, whereas the opposite was true for Guaymas Basin. The diversity and richness of diffuse flow-specific microbial communities were strongly correlated to the relative abundance of Epsilonproteobacteria, proximity to macrofauna, and hydrothermal system type. Archaeal diversity was higher than or equivalent to bacterial diversity in about one third of the samples. Most diffuse flow-specific communities were dominated by OTUs associated with Epsilonproteobacteria, but many of the Guaymas Basin diffuse flow samples were dominated by either OTUs within the Planctomycetes or hyperthermophilic Archaea. This study emphasizes the unique microbial communities associated with geochemically and geographically distinct hydrothermal diffuse flow environments
Integration Schemes for Dissipative Particle Dynamics Simulations: From Softly Interacting Systems Towards Hybrid Models
We examine the performance of various commonly used integration schemes in
dissipative particle dynamics simulations. We consider this issue using three
different model systems, which characterize a variety of different conditions
often studied in simulations. Specifically we clarify the performance of
integration schemes in hybrid models, which combine microscopic and meso-scale
descriptions of different particles using both soft and hard interactions. We
find that in all three model systems many commonly used integrators may give
rise to surprisingly pronounced artifacts in physical observables such as the
radial distribution function, the compressibility, and the tracer diffusion
coefficient. The artifacts are found to be strongest in systems, where
interparticle interactions are soft and predominated by random and dissipative
forces, while in systems governed by conservative interactions the artifacts
are weaker. Our results suggest that the quality of any integration scheme
employed is crucial in all cases where the role of random and dissipative
forces is important, including hybrid models where the solvent is described in
terms of soft potentials
(η6-Benzene)(2,2′-bipyridine-κ2 N,N′)chloridoruthenium(II) chloride methanol sesquisolvate
In the title compound, [RuCl(C6H6)(C10H8N2)]Cl·1.5CH4O, the RuII atom is in a distorted octahedral environment coordinated by an η6-benzene ring, a chelating 2,2′-bipyridine ligand and a chloride ion. The asymmetric unit is completed by a chloride anion and two methanol molecules, one of which is disordered about a centre of inversion with an occupancy of 0.5. It is an example of a ruthenium complex with a less sterically congested environment than in similar derivatives. In the crystal structure, O—H⋯Cl hydrogen bonds, together with π–π stacking interactions [centroid–centroid distances of 3.472Å(2) Å], stabilize the structure
A commentary on Xenophon's 'Àpologia Sokratous'
This thesis is a commentary on Xenophon the Athenian's (Apology of Socrates), a work written in the first half of the 4th century B.C. with the express purpose of explaining Socrates' self-aggrandizing behaviour during his trial in 399. The commentary is prefaced by three essays which treat the issues of authenticity, dating, and possible non-Platonic influences on the work, while the four appendices contain comparisons with Xenophon's Memorabilia and Plato's Apology as well as treatments of Socrates' daimonic sign and his arrogant behaviour during the trial as described by Xenophon. Based on the 1919 Oxford Classical Text edited by E. C. Marchant, the commentary itself is a line-by-line analysis concerned primarily with providing a social, historical, and literary context for each passage under consideration
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Decreased monsoon precipitation in the Northern Hemisphere due to anthropogenic aerosols
The Northern Hemisphere monsoons are an integral component of Earth's hydrological cycle and affect the lives of billions of people. Observed precipitation in the monsoon regions underwent substantial changes during the second half of the 20th century, with drying from the 1950s to mid-1980s and increasing precipitation in recent decades. Modeling studies suggest anthropogenic aerosols has been a key factor driving changes in tropical and monsoon precipitation. Here we apply detection and attribution methods to determine whether observed changes are driven
by human influences using fingerprints of individual forcings (i.e. greenhouse gas, anthropogenic aerosol and natural) derived from climate models. The results show that the observed changes can only be explained when including the influence of anthropogenic aerosols, even after accounting for internal climate variability. Anthropogenic aerosol, not greenhouse gas or natural forcing, has been the dominant influence on Northern Hemisphere monsoon precipitation over the second half of the 20th century
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