2,580 research outputs found

    Activated Protective Fabric

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    Disclosed are fibrous activated materials that can remove and/or deactivate potentially dangerous airborne agents from a gas or air stream. Disclosed materials are multi-layer materials that include a fibrous nonwoven interceptor layer and an active layer immediately adjacent the interceptor layer. The interceptor layer is a fibrous membrane of very low basis weight and defines a relatively low porosity, and the active layer describes geometries, chemistries, etc. that can entrap and/or decontaminate compounds contained in an airstream passing through the material. Disclosed materials can be utilized in forming protective garments, face masks, and the like

    THE ASSOCIATION BETWEEN STATIC FOOT POSTURE AND PEAK PATELLAR TENDON FORCE DURING SINGLE-LEG LANDINGS: PRELIMINARY FINDINGS

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    Patellar tendinopathy is particularly prevalent in jumping-sport athletes and develops due to chronic overloading without appropriate load modification. Pronated and supinated foot postures have been suggested to be associated with the development of the injury. This study aimed to investigate the association between static foot posture, measured using the Foot Posture Index (FPI), and peak patellar tendon force during single-leg drop landings. Kinetic and kinematic data were collected during a single-leg landing task and used to estimate peak patellar tendon force. There was no statistically significant association between FPI and peak patellar tendon force during landing (p = 0.910). Further research investigating how foot posture may affect lower limb loading during landing is required to inform pre-screening and rehabilitation protocols for jumping sport athletes

    The photochemistry of rhenium(I) tricarbonyl N-heterocyclic carbene complexes

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    The photophysical and photochemical properties of the new tricarbonyl rhenium(I) complexes bound to N-heterocyclic carbene ligands (NHC), fac-[Re(CO)3(N^C)X] (N^C = 1-phenyl-3-(2-pyridyl)imidazole or 1-quinolinyl-3-(2-pyridyl)imidazole; X = Cl or Br), are reported. The photophysics of these complexes highlight phosphorescent emission from triplet metal-to-ligand (3MLCT) excited states, typical of tricarbonyl rhenium(I) complexes, with the pyridyl-bound species displaying a ten-fold shorter excited state lifetime. On the other hand, these pyridyl-bound species display solvent-dependent photochemical CO dissociation following what appear to be two different mechanisms, with a key step being the formation of cationic tricarbonyl solvato-complexes, being themselves photochemically active. The photochemical mechanisms are illustrated with a combination of NMR, IR, UV-Vis, emission and X-ray structural characterization techniques, clearly demonstrating that the presence of the NHC ligand is responsible for the previously unobserved photochemical behavior in other photoactive tricarbonyl rhenium(I) species. The complexes bound to the quinolinyl-NHC ligand (which possess a lower-energy 3MLCT) are photostable, suggesting that the photoreactive excited state is not any longer thermally accessible. The photochemistry of the pyridyl complexes was investigated in acetonitrile solutions and also in the presence of triethylphosphite, showing a competing and bifurcated photoreactivity promoted by the trans effect of both the NHC and phosphite ligands

    A Second Giant Planet in 3:2 Mean-Motion Resonance in the HD 204313 System

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    We present 8 years of high-precision radial velocity (RV) data for HD 204313 from the 2.7 m Harlan J. Smith Telescope at McDonald Observatory. The star is known to have a giant planet (M sin i = 3.5 M_J) on a ~1900-day orbit, and a Neptune-mass planet at 0.2 AU. Using our own data in combination with the published CORALIE RVs of Segransan et al. (2010), we discover an outer Jovian (M sin i = 1.6 M_J) planet with P ~ 2800 days. Our orbital fit suggests the planets are in a 3:2 mean motion resonance, which would potentially affect their stability. We perform a detailed stability analysis, and verify the planets must be in resonance.Comment: Accepted for publication in Ap

    The McDonald Observatory Planet Search: New Long-Period Giant Planets, and Two Interacting Jupiters in the HD 155358 System

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    We present high-precision radial velocity (RV) observations of four solar-type (F7-G5) stars - HD 79498, HD 155358, HD 197037, and HD 220773 - taken as part of the McDonald Observatory Planet Search Program. For each of these stars, we see evidence of Keplerian motion caused by the presence of one or more gas giant planets in long-period orbits. We derive orbital parameters for each system, and note the properties (composition, activity, etc.) of the host stars. While we have previously announced the two-gas-giant HD 155358 system, we now report a shorter period for planet c. This new period is consistent with the planets being trapped in mutual 2:1 mean-motion resonance. We therefore perform an in-depth stability analysis, placing additional constraints on the orbital parameters of the planets. These results demonstrate the excellent long-term RV stability of the spectrometers on both the Harlan J. Smith 2.7 m telescope and the Hobby-Eberly telescope.Comment: 38 pages, 10 figures, 6 tables. Accepted for publication in Ap

    Early medieval place-names and riverine flood histories: a new approach and new chronostratigraphic records for three English rivers

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    Environmental information from place-names has largely been overlooked by geoarchaeologists and fluvial geomorphologists in analyses of the depositional histories of rivers and floodplains. Here, new flood chronologies for the rivers Teme, Severn, and Wye are presented, modelled from stable river sections excavated at Broadwas, Buildwas, and Rotherwas. These are connected by the Old English term *wæsse, interpreted as ‘land by a meandering river which floods and drains quickly’. The results reveal that, in all three places, flooding during the early medieval period occurred more frequently between AD 350–700 than between AD 700–1100, but that over time each river's flooding regime became more complex including high magnitude single events. In the sampled locations, the fluvial dynamics of localized flood events had much in common, and almost certainly differed in nature from other sections of their rivers, refining our understanding of the precise nature of flooding which their names sought to communicate. This study shows how the toponymic record can be helpful in the long-term reconstruction of historic river activity and for our understanding of past human perceptions of riverine environments

    Modeling the magnetic field in the galactic disk using new rotation measure observations from the Very Large Array

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    We have determined 194 Faraday rotation measures (RMs) of polarized extragalactic radio sources using new, multi-channel polarization observations at frequencies around 1.4 GHz from the Very Large Array (VLA) in the Galactic plane at 17◦ ≤ l ≤ 63◦ and 205◦ ≤ l ≤ 253◦. This catalog fills in gaps in the RM coverage of the Galactic plane between the Canadian Galactic Plane Survey and Southern Galactic Plane Survey. Using this catalog we have tested the validity of recently-proposed axisymmetric and bisymmetric models of the largescale (or regular) Galactic magnetic field, and found that of the existing models we tested, an axisymmetric spiral model with reversals occurring in rings (as opposed to along spiral arms) best matched our observations. Building on this, we have performed our own modeling, using RMs from both extragalactic sources and pulsars. By developing independent models for the magnetic field in the outer and inner Galaxy, we conclude that in the inner Galaxy, the magnetic field closely follows the spiral arms, while in the outer Galaxy, the field is consistent with being purely azimuthal. Furthermore, the models contain no reversals in the outer Galaxy, and together seem to suggest the existence of a single reversed region that spirals out from the Galactic cente
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