Influence of organic films on the evaporation and condensation of water in aerosol

Uncertainties in quantifying the kinetics of evaporation and condensation of water from atmospheric aerosol are a significant contributor to the uncertainty in predicting cloud droplet number and the indirect effect of aerosols on climate. The influence of aerosol particle surface composition, particularly the impact of surface active organic films, on the condensation and evaporation coefficients remains ambiguous. Here, we report measurements of the influence of organic films on the evaporation and condensation of water from aerosol particles. Significant reductions in the evaporation coefficient are shown to result when condensed films are formed by monolayers of long-chain alcohols [C(n)H((2n+1))OH], with the value decreasing from 2.4 × 10(−3) to 1.7 × 10(−5) as n increases from 12 to 17. Temperature-dependent measurements confirm that a condensed film of long-range order must be formed to suppress the evaporation coefficient below 0.05. The condensation of water on a droplet coated in a condensed film is shown to be fast, with strong coherence of the long-chain alcohol molecules leading to islanding as the water droplet grows, opening up broad areas of uncoated surface on which water can condense rapidly. We conclude that multicomponent composition of organic films on the surface of atmospheric aerosol particles is likely to preclude the formation of condensed films and that the kinetics of water condensation during the activation of aerosol to form cloud droplets is likely to remain rapid

Seasonal Movements, Migratory Behavior, and Site Fidelity of West Indian Manatees along the Atlantic Coast of the United States as Determined by Radio-telemetry

The study area encompassed the eastern coasts of Florida, Georgia, and South Carolina, including inland waterways such as the St. Johns River (Fig. 1). Manatees inhabited the relatively narrow band of water that lies between the barrier beaches and the mainland, occasionally venturing into the ocean close to shore. Between Miami and Fernandina Beach, Florida, 19 inlets provided manatees with corridors between the intracoastal waters and the Atlantic Ocean; the distance between adjacent inlets averaged 32 km(SD = 24 km) and varied from 3 to 88 km. Habitats used by manatees along this 900-km stretch ofcoastline varied widely and included estuaries, lagoons, rivers and creeks, shallow bays and sounds, and ocean inlets. Salinities in most areas were brackish, but ranged from completely fresh to completely marine. The predominant communities of aquatic vegetation also varied geographically and with salinity: seagrass meadows and mangrove swamps in brackish and marine waters along the southern half of peninsular Florida; salt marshes in northeastern Florida and Georgia; benthic macroalgae in estuarine and marine habitats; and a variety of submerged, floating, and emergent vegetation in freshwater rivers, canals, and streams throughout the region. Radio-telemetry has been used successfully to track manatees in other regions ofFlorida (Bengtson 1981, Powell and Rathbun 1984, Lefebvre and Frohlich 1986, Rathbun et al. 1990) and Georgia (Zoodsma 1991), but these early studies relied primarily on conventional VHF (very high frequency) transmitters and were limited in their spatial and temporal scope (see O'Shea and Kochman 1990 for overview). Typically, manatees were tagged at a thermal refuge in the winter and then tracked until the tag detached, usually sometime between the spring and fall of the same year. Our study differs from previous research on manatee movements in several important respects. First, we relied heavily on data from satellite-monitored transmitters using the Argos system, which yielded a substantially greater number of locations and more systematic collection of data compared to previous VHF tracking studies (Deutsch et al. 1998). Second, our tagging and tracking efforts encompassed the entire range of manatees along the Atlantic coast, from the Florida Keys to South Carolina, so inferences were not limited to a small geographic area. Third, we often used freshwater to lure manatees to capture sites, which allowed tagging in all months of the year; this provided more information about summer movement patterns than had previous studies which emphasized capture and tracking at winter aggregations. Finally, the study spanned a decade, and success in retagging animals and in replacing transmitters allowed long-term tracking ofmany individuals. This provided the opportunity to investigate variation in seasonal movements, migratory behavior, and site fidelity across years for individual manatees. (254 page document.

In vivo substrates of the lens molecular chaperones αA-crystallin and αB-crystallin

αA-crystallin and αB-crystallin are members of the small heat shock protein family and function as molecular chaperones and major lens structural proteins. Although numerous studies have examined their chaperone-like activities in vitro, little is known about the proteins they protect in vivo. To elucidate the relationships between chaperone function, substrate binding, and human cataract formation, we used proteomic and mass spectrometric methods to analyze the effect of mutations associated with hereditary human cataract formation on protein abundance in αA-R49C and αB-R120G knock-in mutant lenses. Compared with age-matched wild type lenses, 2-day-old αA-R49C heterozygous lenses demonstrated the following: increased crosslinking (15-fold) and degradation (2.6-fold) of αA-crystallin; increased association between αA-crystallin and filensin, actin, or creatine kinase B; increased acidification of βB1-crystallin; increased levels of grifin; and an association between βA3/A1-crystallin and αA-crystallin. Homozygous αA-R49C mutant lenses exhibited increased associations between αA-crystallin and βB3-, βA4-, βA2-crystallins, and grifin, whereas levels of βB1-crystallin, gelsolin, and calpain 3 decreased. The amount of degraded glutamate dehydrogenase, α-enolase, and cytochrome c increased more than 50-fold in homozygous αA-R49C mutant lenses. In αB-R120G mouse lenses, our analyses identified decreased abundance of phosphoglycerate mutase, several β- and γ-crystallins, and degradation of αA- and αB-crystallin early in cataract development. Changes in the abundance of hemoglobin and histones with the loss of normal α-crystallin chaperone function suggest that these proteins also play important roles in the biochemical mechanisms of hereditary cataracts. Together, these studies offer a novel insight into the putative in vivo substrates of αA- and αB-crystallin

Dynamics of particle size on inhalation of environmental aerosol and impact on deposition fraction

Inhalation of elevated levels of particulate air pollution has been shown to elicit the onset of adverse health effects in humans, where the magnitude of the response is a product of where in the lung the particulate dose is delivered. At any point in time during inhalation the depositional flux of the aerosol is a function of the radius of the droplet, thus a detailed understanding of the rate and magnitude of the mass flux of water to the droplet during inhalation is crucial. In this study, we assess the impact of aerosol hygroscopicity on deposited dose through the inclusion of a detailed treatment of the mass flux of water to account for the dynamics of particle size in a modified version of the standard International Commission on Radiological Protection (ICRP) whole lung deposition model. The ability to account for the role of the relative humidity (RH) of the aerosol prior to, and during, inhalation on the deposition pattern is explored, and found to have a significant effect on the deposition pattern. The model is verified by comparison to previously published measurements, and used to demonstrate that ambient RH affects where in the lung indoor particulate air pollution is delivered

Four nearby L dwarfs

We present spectroscopic, photometric and astrometric observations of four bright L dwarfs identified in the course of the 2MASS near-infrared survey. Our spectroscopic data extend to wavelengths shortward of 5000\AA in the L0 dwarf 2MASSJ0746+2000 and the L4 dwarf 2MASSJ0036+1840, allowing the identification of absorption bands due to MgH and CaOH. The atomic resonance lines Ca I 4227\AA and Na I 5890/5896\AA are extremely strong, with the latter having an equivalent width of 240\AA in the L4 dwarf. By spectral type L5, the D lines extend over $\sim1000$\AA and absorb a substantial fraction of the flux emitted in the V band, with a corresponding effect on the (V-I) broadband colour. The KI resonance doublet at 7665/7699\AA increases in equivalent width from spectral type M3 to M7, but decreases in strength from M7 to L0 before broadening substantially at later types. These variations are likely driven by dust formation in these cool atmospheres.Comment: to appear in AJ, January 2000; 27 pages, including 3 tables and 7 figures embedded in the tex

Hubble Space Telescope NICMOS Observations of T Dwarfs: Brown Dwarf Multiplicity and New Probes of the L/T Transition

We present the results of a Hubble Space Telescope NICMOS imaging survey of 22 T-type field brown dwarfs. Five are resolved as binary systems with angular separations of 0"05-0"35, and companionship is established on the basis of component F110W-F170M colors (indicative of CH4 absorption) and low probabilities of background contamination. Prior ground-based observations show 2MASS 1553+1532AB to be a common proper motion binary. The properties of these systems - low multiplicity fraction (11[+7][-3]% resolved, as corrected for sample selection baises), close projected separations (a = 1.8-5.0 AU) and near-unity mass ratios - are consistent with previous results for field brown dwarf binaries. Three of the binaries have components that span the poorly-understood transition between L dwarfs and T dwarfs. Spectral decomposition analysis of one of these, SDSS 1021-0304AB, reveals a peculiar flux reversal between its components, as its T5 secondary is ~30% brighter at 1.05 and 1.27 micron than its T1 primary. This system, 2MASS 0518-2828AB and SDSS 1534+1615AB all demonstrate that the J-band brightening observed between late-type L to mid-type T dwarfs is an intrinsic feature of this spectral transition, albeit less pronounced than previously surmised. We also find that the resolved binary fraction of L7 to T3.5 dwarfs is twice that of other L and T dwarfs, an anomaly that can be explained by a relatively rapid evolution of brown dwarfs through the L/T transition, perhaps driven by dynamic (nonequilibrium) depletion of photospheric condensates.Comment: ~40 pages, 17 figures, accepted for publication to ApJ. Note that emulateapj style file cuts off part of Table

A New X-Ray Analysis of the Open Cluster Blanco 1 Using Wide-Field BVIc Photometric and Proper Motion Surveys

We perform a new analysis of the extant ROSAT and XMM-Newton X-ray surveys of the southern open cluster Blanco 1, utilizing new BVIc photometric and proper motion data sets. In our study, we match optical counterparts to 47 X-ray sources associated with Blanco 1 cluster members, 6 of which were listed in previous X-ray studies as cluster nonmembers. Our new catalog of optical counterparts to X-ray sources clearly traces out the Blanco 1 main sequence in a CMD, extending from early G to mid-M spectral types. Additionally, we derive new Lx as well as Lx/Lbol ratios for confirmed cluster members. We compare these X-ray properties to other young open clusters, including the coeval Pleiades cluster, to investigate the relationship between age and X-ray activity. We find that stars in Blanco 1 generally exhibit X-ray properties similar to those of other open clusters, namely increasing Lx/Lbol with reducing mass for earlier-type stars, and a saturation limit of Lx/Lbol at a magnitude of 10^-3 for stars with V-Ic > 1.25. More generally, the X-ray detected stars in Blanco 1 have X-ray emission magnitudes that agree with the overall trends seen in the other young clusters. In a direct comparison of Blanco 1 to the Pleiades open cluster, members of both clusters have similar X-ray characteristics; however, there does appear to be some discrepancies in the distribution of Lx/Lbol as a function of color that may be related to scatter seen in the Pleiades CMD. Moreover, previous comparisons of this nature for Blanco 1 were not possible due to the reliance on photographic photometry. This is where the power of precise, homogeneous, and standardized CCD photometry allows for a high fidelity, detailed study of the X-ray properties of stars in Blanco 1. [abridged]Comment: 16 Pages, 11 Figures, 4 Tables, accepted for publication in The Astronomical Journa

Dynamics of aerosol size during inhalation : Hygroscopic growth of commercial nebulizer formulations

We thank the Elizabeth Blackwell Institute (EBI) for financial support through the EBI Early Career Research Fellowship awarded to AEH, and the EPSRC for financial support through a Leadership Fellowship awarded to JPR (grant reference EP/G007713/1). This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are creditedThe size of aerosol particles prior to, and during, inhalation influences the site of deposition within the lung. As such, a detailed understanding of the hygroscopic growth of an aerosol during inhalation is necessary to accurately model the deposited dose. In the first part of this study, it is demonstrated that the aerosol produced by a nebulizer, depending on the airflows rates, may experience a (predictable) wide range of relative humidity prior to inhalation and undergo dramatic changes in both size and solute concentration. A series of sensitive single aerosol analysis techniques are then used to make measurements of the relative humidity dependent thermodynamic equilibrium properties of aerosol generated from four common nebulizer formulations. Measurements are also reported of the kinetics of mass transport during the evaporation or condensation of water from the aerosol. Combined, these measurements allow accurate prediction of the temporal response of the aerosol size prior to and during inhalation. Specifically, we compare aerosol composed of pure saline (150 mM sodium chloride solution in ultrapure water) with two commercially available nebulizer products containing relatively low compound doses: Breath, consisting of a simple salbutamol sulfate solution (5 mg/2.5 mL; 1.7 mM) in saline, and Flixotide Nebules, consisting of a more complex stabilized fluticasone propionate suspension (0.25 mg/mL; 0.5 mM in saline. A mimic of the commercial product Tobi (60 mg/mL tobramycin and 2.25 mg/mL NaC1, pH 5.5-6.5) is also studied, which was prepared in house. In all cases, the presence of the pharmaceutical was shown to have a profound effect on the magnitude, and in some cases the rate, of the mass flux of water to and from the aerosol as compared to saline. These findings provide physical chemical evidence supporting observations from human inhalation studies, and suggest that using the growth dynamics of a pure saline aerosol in a lung inhalation model to represent nebulizer formulations may not be representative of the actual behavior of the aerosolized drug solutions. (C) 2014 Published by Elsevier B.V.Peer reviewe

First Successful Capture and Satellite Tracking of a West Indian Manatee (Trichechus manatus) in Panama: Feasibility of Capture and Telemetry Techniques

It is currently unknown how important the Central American countries south of Belize are as a link between manatee populations in the north (Belize and Mexico) and populations in South America. Therefore, apart from knowing where manatees are found, it is important to understand how manatees are using these habitats and if they are moving between countries or distinct population centers. Here we report the results of a multi-national and multiinstitutional collaboration resulting in the first successful capture and satellite tracking of a West Indian manatee in southern Central America