Multi-approach quantification of denudation rates in the Gulf of Lion source-to-sink system (SE France)

NASA Astrophysics Data System (ADS)

Molliex, S.; Rabineau, M.; Leroux, E.; Bourlès, D. L.; Authemayou, C.; Aslanian, D.; Chauvet, F.; Civet, F.; Jouët, G.

2016-06-01

During the Pliocene and the Quaternary, the Gulf of Lion, the northern passive margin of the Liguro-Provençal basin in the western Mediterranean Sea, received sediments from a 120 000 km2 drainage area constituted by several structural domains. The denudation of mountainous areas, source of this sedimentary supply, results from complex interactions between tectonics, climate, morphology, and rock erodibility. In this study, denudation rates from the present-day and ranging back to the Quaternary and the Pliocene are quantified using four independent methods allowing an investigation over different time scales: 1) compilation of present-day measured sediment fluxes, 2) determination of catchment-scale cosmogenic denudation rates through measurements of in situ-produced 10Be concentrations in sands sampled at the outlet of present-day rivers, 3) estimation of eroded volumes within catchments using a DEM to quantify long-term averaged Quaternary denudation rates, and 4) quantification of sediment volumes deposited within the marine realm of the Gulf of Lion. The results obtained by these four methods are in agreement within the range of uncertainties. The internal part of the Alps exhibits significantly higher denudation rates (∼700 mm ka-1) than those estimated in the other structural domains: 150-250 mm ka-1 in the foreland Alps, ∼100 mm ka-1 in the Pyrenees, and 55-75 mm ka-1 in the Massif Central. The Alpine domain provides at least 80% of the total eroded volume supplied towards the Gulf of Lion. A quantitative geomorphological approach shows that denudation rates are controlled at the first order by catchment morphologies (slope, relief) over different time scales, suggesting glacial conditioning to be the main driver on denudation from the Quaternary to present-day. Throughout the Pliocene-Quaternary, a doubling of denudation rates related to the mid-Pleistocene Revolution (∼0.9 Ma) is highlighted.

Determination of denudation rates by the measurement of meteoric 10Be in Guadiana river sediment samples (Spain) by low-energy AMS.

PubMed

Padilla, S; López-Gutiérrez, J M; Sampath, D M R; Boski, T; Nieto, J M; García-León, M

2018-09-01

The concentration of meteoric 10 Be in estuarine sediment samples has been measured by Spanish Accelerator for Radionuclides Analysis (SARA) at CNA and subsequently used to assess the denudation rate in Guadiana river basin together with the sediment budget method, on both sides of the frontier between Spain and Portugal. The two methods yielded coincident results. The estimation by the 10 Be method gave the denudation rate of (0.76 ± 0.10) × 10 -2  cm/y. After correcting for an approximate 80% attenuation of the sediment discharge into the ocean, caused by the river dams, the sediment budget method yielded the rate of (0.77 ± 0.17) × 10 -2  cm/y. Copyright © 2018 Elsevier Ltd. All rights reserved.

Changes in denudation rates and erosion processes in the transition from a low-relief, arid orogen interior to a high-relief, humid mountain-front setting, Toro Basin, southern Central Andes

NASA Astrophysics Data System (ADS)

Tofelde, S.; Düsing, W.; Schildgen, T. F.; Wittmann, H.; Alonso, R. N.; Strecker, M. R.

2017-12-01

In tectonically active mountain belts positive correlations between denudation rates and hillslope angles are commonly observed, supporting the notion that landscape morphology may reflect tectonic forcing. However, this relationship generally breaks down at 30°, when hillslopes reach threshold angles. Beyond this threshold, faster denudation may occur by an increased contribution from mass-wasting processes. We test this idea in the 4000 km2 Toro Basin, a fault-bounded basin in the Eastern Cordillera of the southern Central Andes. This N-S oriented basin is located between low-relief, arid conditions in the orogen interior (N) and a high-relief, humid setting at its fluvial outlet (S). We measured in-situ produced 10Be concentration in fluvial sediments, which can be converted into basin-mean denudation rates, assuming a spatially uniform contribution of sediment from the catchment. However, in landslide-influenced areas, this assumption is often violated. Previous studies have suggested that clast-size material is mainly contributed by mass-wasting processes, whereas sand is derived from a broad range of erosional processes. Hence, a combination of clast and sand samples can reveal information about the basin-mean denudation rate as well as the contribution of mass-wasting processes. We sampled 13 pebble (1-3 cm) and sand (250-500 µm) pairs across the basin. The sand-derived denudation rates increase from N to S, ranging from 0.010 mm/yr to 1.337 mm/yr, and reveal a non-linear positive correlation with median basin slope. The clast/sand ratios also increase from N to S, indicating amplified mass-wasting processes with increasing slopes. To test if our ratios represent a real shift in erosional processes, we mapped different erosional processes in the study area (e.g. deep-seated landslides, scree erosion,.., diffusion). We assume that today's distribution of processes has not changed over the integration time of 10Be derived denudation rates. This detailed erosion inventory indicates a shift in the dominant erosional processes with increasing clast/sand ratios and thus with increasing slopes. We provide empirical data supporting the hypothesis that higher denudation rates can be achieved by an increased contribution of mass-wasting processes after threshold slopes have been reached.

Cenozoic landforms and post-orogenic landscape evolution of the Balkanide orogen: Evidence for alternatives to the tectonic denudation narrative in southern Bulgaria

NASA Astrophysics Data System (ADS)

Gunnell, Y.; Calvet, M.; Meyer, B.; Pinna-Jamme, R.; Bour, I.; Gautheron, C.; Carter, A.; Dimitrov, D.

2017-01-01

Continental denudation is the mass transfer of rock from source areas to sedimentary depocentres, and is typically the result of Earth surface processes. However, a process known as tectonic denudation is also understood to expose deep-seated rocks in short periods of geological time by displacing large masses of continental crust along shallow-angle faults, and without requiring major contributions from surface erosion. Some parts of the world, such as the Basin and Range in the USA or the Aegean province in Europe, have been showcased for their Cenozoic tectonic denudation features, commonly described as metamorphic core-complexes or as supradetachment faults. Based on 22 new apatite fission-track (AFT) and 21 helium (AHe) cooling ages among rock samples collected widely from plateau summits and their adjacent valley floors, and elaborating on inconsistencies between the regional stratigraphic, topographic and denudational records, this study frames a revised perspective on the prevailing tectonic denudation narrative for southern Bulgaria. We conclude that conspicuous landforms in this region, such as erosion surfaces on basement-cored mountain ranges, are not primarily the result of Paleogene to Neogene core-complex formation. They result instead from "ordinary" erosion-driven, subaerial denudation. Rock cooling, each time suggesting at least 2 km of crustal denudation, has exposed shallow Paleogene granitic plutons and documents a 3-stage wave of erosional denudation which progressed from north to south during the Middle Eocene, Oligocene, Early to Middle Miocene, and Late Miocene. Denudation initially prevailed during the Paleogene under a syn-orogenic compressional regime involving piggyback extensional basins (Phase 1), but subsequently migrated southward in response to post-orogenic upper-plate extension driven by trench rollback of the Hellenic subduction slab (Phase 2). Rare insight given by the denudation pattern indicates that trench rollback progressed at a mean velocity of 3 to 4 km/Ma. The Neogene horst-and-graben mosaic that defines the modern landscape (Phase 3) has completely overprinted the earlier fabrics of Phases 1 and 2, and has been the prime focus of tectonic geomorphologists working in the region. The new narrative proposed here for linking the geodynamic evolution of SE Europe with surface landform assemblages raises issues in favour of better documenting the regional sedimentary record of existing Paleogene basins, which constitute a poorly documented missing link to the thermochronological evidence presented here.

Coupling of physical erosion and chemical weathering after phases of intense human activity

NASA Astrophysics Data System (ADS)

Schoonejans, Jerome; Vanacker, Veerle; Opfergelt, Sophie; Ameijeiras-Mariño, Yolanda; Kubik, Peter W.

2014-05-01

Anthropogenic disturbance of natural vegetation profoundly alters the lateral and vertical fluxes of soil nutrients and particles at the land surface. Human-induced acceleration of soil erosion can thereby result in an imbalance between physical erosion, soil production and chemical weathering. The (de-)coupling between physical erosion and chemical weathering in ecosystems with strong anthropogenic disturbances is not yet fully understood, as earlier studies mostly focused on natural ecosystems. In this study, we explore the chemical weathering intensity for four study sites located in the Internal Zone of the Spanish Betic Cordillera. Most of the sites belong to the Nevado-Filabres complex, but are characterized by different rates of long-term exhumation, 10Be catchment-wide denudation and hill slope morphology. Denudation rates are generally low, but show large variation between the three sites (from 23 to 246 mm kyr-1). The magnitude of denudation rates is consistent with longer-term uplift rates derived from marine deposits, fission-track measurements and vertical fault slip rates. Two to three soil profiles were sampled per study site at exposed ridge tops. All soils overly fractured mica schist, and are very thin (< 60cm). In each soil profile, we sampled 5 depth slices, rock fragments and the (weathered) bedrock. In total, 38 soil and 20 rock samples were analyzed for their chemical composition. The chemical weathering intensity is constrained by the Chemical Depletion Fraction that is based on a chemical mass balance approach using Zr as an immobile element. Chemical weathering accounts for 5 to 35% of the total mass lost due to denudation. We observe systematically higher chemical weathering intensities (CDFs) in sites with lower denudation rates (and vice versa), suggesting that weathering is supply-limited. Our measurements of soil elemental losses from 10 soil profiles suggest that the observed variation in chemical weathering is strongly associated with long-term 10Be derived denudation rates, and tectonic uplift rates. Our data do not provide direct evidence of an imbalance between soil production and chemical weathering, despite more than 2000 years of intense human activity.

High-capacity NO2 denuder systems operated at various temperatures (298-473 K).

PubMed

Wolf, Jan-Christoph; Niessner, Reinhard

2012-12-01

In this study, we investigated several coatings for high-temperature, high-capacity, and high-efficiency denuder-based NO(2) removal, with the scope to face the harsh conditions and requirements of automotive exhaust gas sampling. As first coating, we propose a potassium iodide (KI)/polyethylene glycol coating with a high removal efficiency (ε > 98%) for about 2 h and 50 ppm NO(2) at room temperature (298 K). At elevated temperatures (423 K), the initial capacity (100 ppmh) is decreased to 15 ppmh. Furthermore, this is the first proposal of the ionic liquid methyl-butyl-imidazolium iodide ([BMIm(+)][I(-)]) as denuder coating material. At room temperature, this ionic liquid exhibits far greater capacity (300 ppmh) and NO(2) removal efficiency (ε > 99.9%) than KI. Nevertheless, KI exhibits a slightly (~10%) higher capacity at elevated temperatures than [BMIm(+)][I(-)]. Both coatings presented are suitable for applications requiring selective denuding of NO(2) at temperatures up to 423 K.

Thermochronologic constraints on Jurassic rift flank denudation in the Thiel Mountains, Antarctica

USGS Publications Warehouse

Fitzgerald, P.G.; Baldwin, S.L.

2007-01-01

The Thiel Mountains are part of the Transantarctic Mountains (TAM) and occupy a strategic position close to the East-West Antarctic boundary. They occur in a region of relatively subdued topography distal from high topography and high relief of most of the TAM adjacent to the West Antarctic rift system. Low-temperature thermochronology on samples collected from the Reed Ridge granite on the north flank of the Thiel Mountains constrain the thermal and hence tectonic history. Apatite fission track data plus thermal models indicate cooling from ca. 165-150 Ma. In conjunction with 40Ar/39Ar K-feldspar data, the results indicate cooling was due to relatively slow erosional denudation, and not thermal relaxation following Jurassic tholeiitic magmatism. Denudation was most likely associated with the formation of the Jurassic rift system across Antarctica that marked the initial breakup of Gondwana. This is the oldest episode of denudation associated with formation of the present day TAM

Development of a coupled diffusion denuder system combined with gas chromatography/mass spectrometry for the separation and quantification of molecular iodine and the activated iodine compounds iodine monochloride and hypoiodous acid in the marine atmosphere.

PubMed

Huang, Ru-Jin; Hoffmann, Thorsten

2009-03-01

This study concerns the development of a coupled diffusion denuder system capable of separating and quantifying gaseous molecular iodine (I(2)) and two other highly reactive iodine species, ICl and HOI, which are collectively named activated iodine compounds (AIC). Both I(2) and AIC are key species in the atmospheric chemistry of iodine. 1,3,5-Trimethoxybenzene (1,3,5-TMB)- and alpha-cyclodextrin/(129)I(-) (alpha-CD/(129)I(-))-coated denuders proved to be suitable for the collection of gaseous AIC and I(2), respectively. The experimental collection efficiencies for AIC (tested as ICl) and I(2) agreed well with the theoretical values for gas flow rates in the range between 300 and 1800 mL min(-1). The coupled denuder system (1,3,5-TMB-coated denuder as front-denuder coupled upstream of an alpha-CD/(129)I(-)-coated denuder) was applied successfully to separate test gas mixtures of ICl and I(2) at various mixing ratios in the laboratory. The operation of both denuder systems was demonstrated to be independent of relative humidity (0-100%) and storage period (at least 2 weeks prior to and after sampling). Detection limits were achieved at sub-parts-per-trillion-by-volume (sub-pptv) level. The presented method provides a reliable and practical approach for the speciation of gaseous iodine compounds. In addition, we report for the first time ambient air measurements of AIC mixing ratios, carried out at the atmospheric research station in Mace Head, Ireland. A maximum concentration of AIC of 30.2 pptv was observed for nighttime measurements and 6.0 pptv for daytime measurements. A similar diurnal pattern was found for I(2) with an average concentration level of 23.2 pptv during daytime and 85.1 pptv during nighttime, indicating a strong correlation with AIC.

Volatilization of PM2.5 Inorganic Ions in a Filter Pack System with Backup Filter and Denuders

NASA Astrophysics Data System (ADS)

Kim, C.; Choi, Y.; Ghim, Y.

2012-12-01

Concentrations of PM2.5 inorganic ions were measured at the rooftop of the 5-story building on the hill (37.02oN, 127.16oE, 167 m above sea level) in the Global Campus of Hankuk University of Foreign Studies, about 35 km southeast of downtown Seoul, Korea. The measurements were made four times during one-year span between 2011 and 2012 by considering the climate of Korea with distinct seasonal variations: July 29 to August 26 (summer); September 14 to October 13 (fall); November 28 to January 4 (winter); February 14 to May 31 (spring). A filter pack system was composed of PM2.5 cyclone, two annular denuders, Teflon filter, nylon filter, and an annular denuder, in series. Two annular denuders were to remove acidic and basic gases prior to collecting particles on the Teflon filter. Nylon filter and an annular denuder were to back up the Teflon filter by absorbing acidic and basic gases, respectively, which were volatilized from collected particles on the Teflon filter. Samplings were made for 24 hours every day. Extracts from filters and denuders were analyzed by ion chromatography to measure concentrations of anions (SO42-, NO3-, Cl-) and cations (Ca2+, Mg2+, NH4+, Na+, K+). The amounts of ionic species absorbed at the backup nylon filter and denuder were examined in terms of meteorological parameters, the amounts of gases removed in front of the Teflon filter, and the amounts of particulate ions collected on the Teflon filter. Major factors to affect the volatilization from particles collected on the Teflon filter were discussed.

Evaluation of an annular denuder system for carbonaceous aerosol sampling of diesel engine emissions.

PubMed

Zhang, Jie; Fan, Xinghua; Graham, Lisa; Chan, Tak W; Brook, Jeffrey R

2013-01-01

Sampling of particle-phase organic carbon (OC) from diesel engines is complicated by adsorption and evaporation of semivolatile organic carbon (SVOC), defined as positive and negative artifacts, respectively. In order to explore these artifacts, an integrated organic gas and particle sampler (IOGAPS) was applied, in which an XAD-coated multichannel annular denuder was placed upstream to remove the gas-phase SVOC and two downstream sorbent-impregnated filters (SIFs) were employed to capture the evaporated SVOC. Positive artifacts can be reduced by using a denuder but particle loss also occurs. This paper investigates the IOGAPS with respect to particle loss, denuder efficiency, and particle-phase OC artifacts by comparing OC, elemental carbon (EC), SVOC, and selected organic species, as well as particle size distributions. Compared to the filterpack methods typically used, the IOGAPS approach results in estimation of both positive and negative artifacts, especially the negative artifact. The positive and negative artifacts were 190 microg/m3 and 67 microg/m3, representing 122% and 43% of the total particle OC measured by the IOGAPS, respectively. However particle loss and denuder break-through were also found to exist. Monitoring particle mass loss by particle number or EC concentration yielded similar results ranging from 10% to 24% depending upon flow rate. Using the measurements of selected particle-phase organic species to infer particle loss resulted in larger estimates, on the order of 32%. The denuder collection efficiencyfor SVOCs at 74 L/min was found to be less than 100%, with an average of 84%. In addition to these uncertainties the IOGAPS method requires a considerable amount of extra effort to apply. These disadvantages must be weighed against the benefits of being able to estimate positive artifacts and correct, with some uncertainty, for the negative artifacts when selecting a method for sampling diesel emissions. Measurements of diesel emissions are necessary to understand their adverse impacts. Much of the emissions is organic carbon covering a range ofvolatilities, complicating determination of the particle fraction because of sampling artifacts. In this paper an approach to quantify artifacts is evaluated for a diesel engine. This showed that 63% of the particle organic carbon typically measured could be the positive artifact while the negative artifact is about one-third of this value. However, this approach adds time and expense and leads to other uncertainties, implying that effort is needed to develop methods to accurately measure diesel emissions.

Present and past denudation rates in the central Tianshan (Central Asia): impact of the Quaternary glaciations?

NASA Astrophysics Data System (ADS)

Charreau, J.; Puchol, N.; Blard, P.; Braucher, R.; Leanni, L.; Bourles, D. L.; Graveleau, F.; Dominguez, S.

2012-12-01

Denudation controls the mass transfer from the uplifting highlands to the lowlands basin. It impacts the isostatic compensation and hence tectonics, the rheology and may drives the Earth climate through its potential impact on atmospheric CO2. Denudation is therefore a key factor governing the evolution of the Earth's surface. Quantitative records of past denudation rates over geological time scales are thus of major importance to untangle the complex interactions between tectonics, climate and surface processes. This is particularly true at the Plio-pleistocene transition where the onset of Quaternary glaciations may have enhanced worldwide denudation rates. The Tianshan stands out as a key area to better address these problems. This range owes its impressive present high topography to the recent deformation due to the India-Asia collision and is moreover sandwiched between two large intracontinental endorheic basins where the total material eroded from the uplifting range may be deciphered from the sedimentary archive. Moreover, here, potential changes in the sediment volume are insensitive to global sea-level variations. Accurate reconstruction of past denudation rate require well-dated sedimentary archives. Over past decades, several magnetostratigraphic studies were carried out in the piedmonts, where remarkable sedimentary sections are exposed in deep rivers entrenchment which expose the thick conglomeratic Xiyu formation, initially assigned to be Plio-pleistocene in age. This led several authors to conclude that, in this region, the sediment fluxes rapidly increaseed at the onset of glaciations. However, absolute magnetostratigraphic dating unambiguously show that this formation is highly diachronous and, therefore, can't owe its origin to a climate change. Given the strong lateral facies variations, reconstruction of past denudation rates from the sedimentary archive require detailed chronostratigraphy and a knowledge of the basin geometry, both almost impossible to achieve. To reconstruct the denudation rates from the sedimentary archives, we have developed an approach based on the analyses of in situ produced cosmogenic isotope (10Be) in sediment. A pioneer study was carried out in the magnetostratigraphically dated Kuitun section. This work showed a possible transient increase in denudation rate in the drainage basin from 4 to 2Ma. Because our study was limited to one single basin and suffered from large uncertainties, it is unclear yet if this change can be related to the onset of glaciations or local tectonic activity. A critical step is to understand how the material is transferred to the basin and what are the main factors controlling the spatial distribution of present-day denudation. Therefore, we have analyzed the 10Be concentrations of 35 samples from modern river sediments located in the Northern and Southern Tianshan piedmonts. Those results will be discussed in the light of a comprehensive morphologic analyses of all the drainage basins, taking into account the influence of tectonics and climate. Finally, the derivation of paleo-denudation rate from cosmogenic isotopes must rely on independent constrained of the watershed paleotopography. Therefore, we will also presents high-resolution oxygen and carbon isotopic records of paleosol carbonates, sampled from the Kuitun section. From these records we conclude that the Kuitun He drainage basin have remained at relatively unchanged elevations for the past 10 Ma.

Controls on the evolution of carbonate landscapes in Provence, France using cosmogenic nuclides

NASA Astrophysics Data System (ADS)

Thomas, Franck; Godard, Vincent; Bellier, Olivier; Shabanian, Esmaeil; Benedetti, Lucilla; Ollivier, Vincent; Rizza, Magali; Hollender, Fabrice; Team Aster; Guillou, Valéry

2016-04-01

The Provence region located in South-Eastern France has registered significant earthquakes in the last 1000 years, some reaching intensities up to IX. It is currently undergoing a very slow tectonic deformation with little seismicity and long recurrence intervals for major earthquakes (such as the 1909 magnitude 6 Lambesc earthquake). Several West-trending ranges are an important part of the landscape, and the influence of tectonic uplift compared to denudation during the Pliocene-Quaternary is not yet fully understood in the region. The geology of South-Eastern France is dominated by a thick Mesozoic series primarily consisting of carbonate rocks. The iconic ranges of Provence resulting from the Pyrenean orogeny (late Eocene) are mostly made up of uplifted lower Cretaceous. A minor reactivation occurred during the more recent Alpine late Cenozoic tectonic phase and contributed to the rejuvenation of the relief. Carbonate rocks are prone to complete chemical dissolution and are thus highly sensitive to climatic forcings such as precipitation. Moreover, the elevation and the frequency of freezing and thawing are parameters strongly influencing the geomorphic evolution in such environments. To investigate on this matter, 42 carbonate rock samples were collected for 36Cl denudation measurements on the Petit Luberon range. Denudation rates have been determined for both bedrock samples from the crest and sediments from rivers draining the southern and northern flanks of the range, allowing insights into long-term relief evolution. We observe a strong denudation contrast between the flanks lowering at 100-200 mm/ka and the summit surface, at around 30 mm/ka. These results suggest a transient evolution and a probable narrowing of the range. In addition, we collected 23 carbonate bedrock samples from other Mesozoic ranges in Provence with a wide altitude range (from 150 up to 1800 meters high asl), for similar 36Cl analysis. Our objective in this study (CEA-Cashima) is to have a regional overview of the distribution of denudation rates in an area dominated by carbonate rocks and to evaluate the influence of altitude, climate and associated processes on erosion and eventually link it to a slow regional uplift. Thus this study will allow a better understanding of the denudation processes in a carbonate dominated area characterized by slow tectonic deformations and moderate precipitations.

Spatial gradient of chemical weathering and its coupling with physical erosion in the soils of the Betic Cordillera (SE Spain)

NASA Astrophysics Data System (ADS)

Schoonejans, Jerome; Vanacker, Veerle; Opfergelt, Sophie; Ameijeiras-Mariño, Yolanda; Kubik, Peter

2015-04-01

The production and denudation of soil material are controlled by chemical weathering and physical erosion which influence one another. Better understanding and quantification of this relationship is critical to understand biogeochemical cycles in the critical zone. The intense silicate weathering that is taking place in young mountain ranges is often cited to be a negative feedback that involves a long-term reduction of the atmospheric CO2 and the temperature cooling. However the possible (de)coupling between weathering and erosion is not fully understood for the moment and could reduce the effect of the feedback. This study is conducted in the eastern Betic Cordillera located in southeast Spain. The Betic Cordillera is composed by several mountains ranges or so-called Sierras that are oriented E-W to SE-NW and rise to 2000m.a.s.l. The Sierras differ in topographic setting, tectonic activity, and slightly in climate and vegetation. The mountain ranges located in the northwest, such as the Sierra Estancias, have the lowest uplift rates ( ~20-30 mm/kyr); while those in the southeast, such as the Sierra Cabrera, have the highest uplift rates ( >150mm/kyr). The sampling was realised into four small catchments located in three different Sierras. In each of them, two to three soil profiles were excavated on exposed ridgetops, and samples were taken by depth slices. The long-term denudation rate at the sites is inferred from in-situ 10Be CRN measurements. The chemical weathering intensity is constrained using a mass balance approach that is based on the concentration of immobile elements throughout the soil profile (CDF). Our results show that the soil depth decreases with an increase of the denudation rates. Chemical weathering accounts for 5 to 35% of the total mass lost due to denudation. Higher chemical weathering intensities (CDFs) are observed in sites with lower denudation rates (and vice versa). The data suggest that chemical weathering intensities are strongly associated with long-term 10Be derived denudation rates. Several causative factors may contribute to this observation, amongst which variation in climate, topography, and vegetation that are all associated with the measured variation in denudation rates. Finally, our data do not support a positive relation between the weathering rate and the physical erosion rate in the soil.

How fast is the denudation of the Taiwan Mountains? (Invited)

NASA Astrophysics Data System (ADS)

Siame, L. L.; Derrieux, F.; KANG, C.; Bourles, D. L.; Braucher, R.; Léanni, L.; Chen, R.; Lee, J.; Chu, H.; Chang, C.; Byrne, T. B.

2013-12-01

Orogenic settings are particularly well suited to study and quantify the coupling relations between tectonics, topography, climate and erosion since they record tectonic evolution along convergent margins and the connection between deep and surface processes. However, the interaction of deep and shallow processes is still poorly understood and the role they play in the exhumation of rocks, the structural and kinematic evolution of orogenic wedges, and the relation between tectonics and climate-dependent surface processes are still debated. Therefore, quantification of denudation rates in a wide range of climatic and tectonic settings, as well as at various time and space scales, is a critical step in calibrating and validating landscape evolution models. In this study, we focus on the mountains of the arc-continent collision in Taiwan, which serve as one of the best examples in the world to understand and study mountain building processes. We investigate the pattern and magnitude of denudation rates at the scale of the orogenic system, deriving denudation rates from in situ-produced cosmogenic nuclide 10Be concentrations measured in (1) river-borne quartz minerals sampled at major watersheds outlets, and (2) bedrock outcrops along ridge crests and at summits located along the major drainage divide of the belt. We determined a denudation pattern showing a clear discrepancy between the western (1.7×0.2 mm/yr) and eastern (4.1×0.5 mm/yr) sides of the range. Conversely, bedrock denudation determined along ridge crests, summits and flat surfaces preserved at high elevations are characterized by significantly lower denudation rates on the order of 0.24×0.03 mm/yr. Altogether, the cosmogenic-derived denudation pattern at the orogen-scale reflects fundamental mountain building processes from frontal accretion in the Western Foothills to basal accretion and fast exhumation in the Central Range. Applied to the whole orogen, such field-based approach thus provides important input data to validate and calibrate the parameters to be supplied to landscape evolution models. Moreover, the comparison between cosmogenic bedrock-derived and basin-derived denudation rates allows discussing how the topographic relief of Taiwan has evolved through the last thousands of years, and thus documenting whether or not the Taiwan Mountains are in a topographic steady state.

Uncertainties in the measurements of water-soluble organic nitrogen in the aerosol

NASA Astrophysics Data System (ADS)

Matsumoto, Kiyoshi; Yamato, Koki

2016-11-01

In order to evaluate the positive and negative artifacts in the measurements of the water-soluble organic nitrogen (WSON) in the aerosols by filter sampling, comparative experiments between the filter sampling and denuder-filter sampling were conducted during both the warm and cold seasons. The results suggest that the traditional filter sampling underestimates the concentrations of the particulate WSON due to its volatilization loss, but this effect on the ratio of the WSON to the water-soluble total nitrogen (WSTN) was small probably because inorganic nitrogen species were also lost during the filter sampling. Approximately 32.5% of the WSON in the PM2.5 was estimated to be lost during the filter sampling. The denuder-filter sampling also demonstrated the existence of the WSON in the gas phase with approximately quarter concentrations of the WSON in the PM2.5. On the other hand, the filter sampling would overestimate the gaseous WSON concentration due to the loss of the WSON from the aerosol collection filter.

Denudation rates of the Southern Espinhaço Range, Minas Gerais, Brazil, determined by in situ-produced cosmogenic beryllium-10

NASA Astrophysics Data System (ADS)

Barreto, Helen N.; Varajão, César A. C.; Braucher, Régis; Bourlès, Didier L.; Salgado, André A. R.; Varajão, Angélica F. D. C.

2013-06-01

To investigate denudation rates in the southern part of the Espinhaço Range (central-eastern Brazil) and to understand how this important resistant and residual relief has evolved in the past 1.38 My, cosmogenic 10Be concentrations produced in situ were measured in alluvial sediments from the three main regional basins, whose substratum is composed primarily of quartzites. The long-term denudation rates (up to 1.38 My) estimated from these measurements were compared with those that affect the western (São Francisco River) and eastern (Doce and Jequitinhonha Rivers) basins, which face the West San Francisco craton and the Atlantic, respectively. Denudation rates were measured in 27 samples collected in catchments of different sizes (6-970 km2) and were compared with geomorphic parameters. The mean denudation rates determined in the northern part are low and similar to those determined in the southern part, despite slightly different geomorphic parameter values (catchment relief and mean slope). For the southern catchments, the values are 4.91 ± 1.01 m My- 1 and 3.65 ± 1.26 m My- 1 for the Doce and São Francisco River basins, respectively; for the northern catchments, they are 4.40 ± 1.06 m My- 1 and 3.96 ± 0.91 m My- 1 for the Jequitinhonha and São Francisco River basins, respectively. These low values of denudation rates suggest no direct correlation if plotted against geomorphic parameters such as the catchment area, maximum elevation, catchment relief, average relief and mean slope gradients. These values show that the regional landscape evolves slowly and is strongly controlled by resistant lithology, with similar erosional rates in the three studied basins.

Denudation rates and tectonic geomorphology of the Spanish Betic Cordillera

NASA Astrophysics Data System (ADS)

Bellin, N.; Vanacker, V.; Kubik, P. W.

2014-03-01

The tectonic control on landscape morphology and long-term denudation is largely documented for settings with high uplift rates. Relatively little is known about the rates of geomorphic response in areas of low tectonic uplift. Here, we evaluate spatial variations in denudation of the Spanish Betic Cordillera based on cosmogenic 10Be-derived denudation rates. Denudation rates are compared to published data on rock uplift and exhumation of the Betic Cordillera to evaluate steady-state topography. The spatial patterns of catchment-wide denudation rates (n=20) are then analysed together with topographic metrics of hillslope and channel morphology. Catchments draining the Betic ranges have relatively low denudation rates (64±54 mm kyr), but also show large variation as they range from 14 to 246 mm kyr-1. Catchment-wide denudation is linearly proportional to the mean hillslope gradient and local relief. Despite large spatial variation in denudation, the magnitude and spatial pattern of denudation rates are generally consistent with longer-term local uplift rates derived from elevated marine deposits, fission-track measurements and vertical fault slip rates. This might be indicative of a steady-state topography where rock uplift is balanced by denudation.

Aerosol Optical Properties of Smoke from the Las Conchas Wildfire, Los Alamos, NM

NASA Astrophysics Data System (ADS)

Gorkowski, K.; Dubey, M. K.; Flowers, B. A.; Aiken, A. C.; Klein, B. Z.; Mazzoleni, C.; Sharma, N.; China`, S.

2011-12-01

The Las Conchas wildfire in Northern New Mexico started on June, 26 2011 and spread rapidly, eventually burning an area of 634 km2 (245 mi2). Due to the close proximity to the fire, the Los Alamos National Laboratory (LANL) was shut down and the town evacuated for several days. Immediately after LANL reopened (7/6/2011) the Earth and Environmental Sciences Division (EES-14) attained unique measurements of the smoke by sampling the ambient air. Three Integrated Photoacoustic/Nephelometer Spectrometers (DMT Inc.) were set up to measure aerosol light absorption and scattering coefficients. A University of Northwest Switzerland thermodenuder was used to remove compounds that are volatile at temperatures up to 200C. The aerosol's optical properties were measured before and after denuding the sample at 405nm (blue), 532nm (green), 781nm (red), and for non-denuded particles also at 375nm (ultraviolet). The aerosol size distributions were measured after the denuder with a Laser Aerosol Spectrometer (LAS, TSI Inc.) and black carbon was measured with a Single Particle Soot Photometer (SP2, DMT Inc.). Additionally, ambient measurements of Total Particulate Matter (PM2.5 and PM10) were collected continuously at the LANL air monitoring stations. These measurements are used in conjunction with numerical simulations to determine the bulk optical properties of the aerosol. Aerosols in wildfire smoke are composed of organic and black carbon (soot) particles that are formed during wood combustion and pyrolysis. The optical properties of the smoke particles are complex and lead to large uncertainties in assessing the global climate. During the measurement period, the Las Conchas fire provided very high particle concentrations (up to 200 μg/m3) that were exploited to investigate their optical properties. By heating the particles to temperatures ranging from 75 to 200C in the denuder, volatile organics were removed and the optical properties of the remaining particles were measured. Denuding of the aerosols, removed the outer organic coatings leaving behind the inner core of black carbon (soot) and any compounds that did not volatize completely. By simultaneously measuring the optical properties of the non-denuded as well as the denuded aerosol, we can study how the coatings affect the optical properties. The absorption coefficient measurements showed that coatings can cause an increase or decrease in absorption. The photoacoustic measurements were also combined with SP2 measurements to gain a mechanistic understanding of the effect of composition on the mass light absorption cross-sections of carbonaceous aerosols emitted by fires.

Monitoring of atmospheric gaseous and particulate polycyclic aromatic hydrocarbons in South African platinum mines utilising portable denuder sampling with analysis by thermal desorption-comprehensive gas chromatography-mass spectrometry.

PubMed

Geldenhuys, G; Rohwer, E R; Naudé, Y; Forbes, P B C

2015-02-06

Concentrations of diesel particulate matter and polycyclic aromatic hydrocarbons (PAHs) in platinum mine environments are likely to be higher than in ambient air due to the use of diesel machinery in confined environments. Airborne PAHs may be present in gaseous or particle phases each of which has different human health impacts due to their ultimate fate in the body. Here we report on the simultaneous sampling of both phases of airborne PAHs for the first time in underground platinum mines in South Africa, which was made possible by employing small, portable denuder sampling devices consisting of two polydimethylsiloxane (PDMS) multi-channel traps connected in series separated by a quartz fibre filter, which only require small, battery operated portable personal sampling pumps for air sampling. Thermal desorption coupled with comprehensive gas chromatography-mass spectrometry (TD-GC×GC-TofMS) was used to analyse denuder samples taken in three different platinum mines. The samples from a range of underground environments revealed that PAHs were predominantly found in the gas phase with naphthalene and mono-methylated naphthalene derivatives being detected at the highest concentrations ranging from 0.01 to 18 μg m(-3). The particle bound PAHs were found in the highest concentrations at the idling load haul dump vehicle exhausts with a dominance of fluoranthene and pyrene. Particle associated PAH concentrations ranged from 0.47 to 260 ng m(-3) and included benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene and benzo[ghi]perylene. This work highlights the need to characterise both phases in order to assess occupational exposure to PAHs in this challenging sampling environment. Copyright © 2015 Elsevier B.V. All rights reserved.

SAMPLING AND ANALYSIS OF SEMIVOLATILE AEROSOLS

EPA Science Inventory

Denuder based samplers can effectively separate semivolatile gases from particles and 'freeze' the partitioning in time. Conversely, samples collected on filters partition mass according to the conditions of the influent airstream, which may change over time. As a result thes...

Parallel-plate wet denuder coupled ion chromatograph for near-real-time detection of trace acidic gases in clean room air.

PubMed

Takeuchi, Masaki; Tsunoda, Hiromichi; Tanaka, Hideji; Shiramizu, Yoshimi

2011-01-01

This paper describes the performance of our automated acidic (CH(3)COOH, HCOOH, HCl, HNO(2), SO(2), and HNO(3)) gases monitor utilizing a parallel-plate wet denuder (PPWD). The PPWD quantitatively collects gaseous contaminants at a high sample flow rate (∼8 dm(3) min(-1)) compared to the conventional methods used in a clean room. Rapid response to any variability in the sample concentration enables near-real-time monitoring. In the developed monitor, the analyte collected with the PPWD is pumped into one of two preconcentration columns for 15 min, and determined by means of ion chromatography. While one preconcentration column is used for chromatographic separation, the other is used for loading the sample solution. The system allows continuous monitoring of the common acidic gases in an advanced semiconductor manufacturing clean room. 2011 © The Japan Society for Analytical Chemistry

Analysis of Individual Carbonaceous Particles Emitted from the Las Conchas Wildfire, Los Alamos, NM, in June-July 2011

NASA Astrophysics Data System (ADS)

Mazzoleni, C.; China, S.; Gorkowski, K.; Flowers, B. A.; Aiken, A. C.; Dubey, M. K.

2012-12-01

Carbonaceous aerosol emitted from biomass burning contributes significantly to atmospheric aerosol loadings regionally and globally. The net direct radiative forcing of biomass burning aerosol can be positive and/or negative and this depends on its composition, morphology and mixing state. Biomass burning aerosols can also change the cloud properties as they can act as cloud condensation nuclei. In this study we investigated biomass burning particles emitted from the Las Conchas wildfire in northern New Mexico that started on June 26, 2011 and burned an area of 245 square miles. Aerosol samples were collected on nucleopore filters at the Los Alamos National Laboratory during the third week of the wildfire event. Individual particles (~4000) were investigated using field-emission scanning electron microscopy and energy dispersive X-ray spectroscopy (EDS) to distinguish different carbonaceous particles and their shape, size, elemental composition and mixing state. A thermo-denuder was used to remove compounds that are volatile at temperatures up to 200 C, leaving behind the black carbon and any compounds that did not volatize completely. Smoke particles consisted of a) tar balls, which are amorphous spherical carbonaceous organic aerosols; b) organic particles with inorganic inclusions, c) soot particles and (d) soot with various inclusions. Two distinct kinds of tar balls, "electronically" dark and bright, were found using the field-emission scanning electron microscopy and were characterized for ambient and denuded conditions to understand coating effects and aging. It was found that dark tar balls are generally larger in size than the bright ones. Additionally, the difference between the size of ambient-bright and the size of denuded-bright tar balls was larger than the difference between the size of ambient-dark and the size of denuded-dark tar balls. EDS analysis showed that 70% of the dark tar balls had higher (~60%) relative oxygen content than in the bright tar balls. We conclude that there are two distinct kinds of biomass burning tar balls and that dark tar balls are less volatile than bright tar balls. The morphology of soot particles was also investigated by evaluating their fractal dimension for both ambient (coated with organic and inorganic material) and denuded samples at two different times of the day. The fractal dimension for ambient soot was found to be higher than for denuded soot due to the coating on the ambient soot particles. Finally, the monomer diameter decreased by up to 25% after denuding the particles. This study provides insights on the link between electron microscopy images of single particles and the mixing state, morphology, and evolution of different biomass burning aerosol at the beginning of their lifecycle.

Kinetically limited weathering at low denudation rates in semi-arid climates

NASA Astrophysics Data System (ADS)

Vanacker, V.; Schoonejans, J.; Opfergelt, S.; Ameijeiras-Marino, Y.; Christl, M.

2016-12-01

On Earth, the Critical Zone supports terrestrial life, being the near-surface environment where interactions between the atmosphere, lithosphere, hydrosphere, and biosphere take place Quantitative understanding of the interaction between mechanical rock breakdown, chemical weathering, and physical erosion is essential for unraveling Earth's biogeochemical cycles. In this study, we explore the role of soil water balance on regulating soil chemical weathering under water deficit regimes. Weathering rates and intensities were evaluated for nine soil profiles located on convex ridge crests of three mountain ranges in the Spanish Betic Cordillera. We present and compare quantitative information on soil weathering, chemical depletion and total denudation that were derived based on geochemical mass balance, 10Be cosmogenic nuclides and U-series disequilibria. Soil production rates determined based on U-series isotopes (238U, 234U, 230Th and 226Ra) are of the same order of magnitude as 10Be-derived denudation rates, suggesting steady state soil thickness, in two out of three sampling sites. The chemical weathering intensities are relatively low (˜5 to 30% of the total denudation of the soil) and negatively correlated with the magnitude of the water deficit in soils. Soil weathering extents increase (nonlinearly) with soil thickness and decrease with increasing surface denudation rates, consistent with kinetically limited or controlled weathering. Our study suggests that soil residence time and water availability limit weathering processes in semi-arid climates, which has not been validated previously with field data. An important implication of this finding is that climatic regimes may strongly regulate soil weathering by modulating soil solute fluxes.

Chemical Denudation and Cation Depletion in a Semi-Arid Catchment of the Long-Term Agroecological Research Observatory

NASA Astrophysics Data System (ADS)

Shaljian, M.; Keller, C. K.; Jones, K. B.; Brooks, E. S.; Huggins, D. R.

2016-12-01

The Long-Term Agroecosystem Research (LTAR) network of the USDA is a nationwide observatory and decadal-timescale field-experimental study of sustainable food production. The LTAR thus supports investigation of hydroecological and biogeochemical processes that could affect agricultural sustainability over the course of the 21st century. Mineral-derived nutrient cations are essential to fertility, and acidification of soils due to chemical fertilization may result in unsustainable chemical denudation of the soil exchange pool. Mineral weathering also contributes to base cation denudation. This study investigated base cation losses for one year in drainage from a semi-arid, rain-fed catchment at the Cook Agronomy Farm (CAF) LTAR site in southeastern Washington. We measured flows, analyzed drainage samples and estimated hydrologic effluxes of base cations from the catchment. The total dissolved base cation denudation rate at CAF-LTAR is about 40 kg ha-1 yr-1, which is comparable to other catchments on silicate terranes. The 2.1keq ha-1 yr-1 of denuded cationic charge is dominated by Ca2+ (61%) and Mg2+ (35%). Principal counter-ions are HCO3- (43%), NO3- (38%) and SO42- (16%), suggesting that both H2CO3 and HNO3 are important acids. Comparing 2008 soil pH and base saturation at CAF-LTAR to a nearby native prairie site, we preliminarily estimate a loss of 120 keq ha-1 of base cations from the upper 1.5m of the soil exchangeable cation pool. Dividing this depletion by the estimated denudation flux returns 60 years, which is approximately the interval of chemically intensive agriculture here. This may suggest that the source of exported base cations in drainage is primarily cation exchange rather than mineral weathering. The LTAR observatory will support ongoing monitoring and experimentation necessary to better understand base cation depletion and how it interacts with agroecological changes over the next several decades.

Carbonate landscapes evolution: Insights from 36Cl

NASA Astrophysics Data System (ADS)

Godard, Vincent; Thomas, Franck; Ollivier, Vincent; Bellier, Olivier; Shabanian, Esmaeil; Miramont, Cécile; Fleury, Jules; Benedetti, Lucilla; Guillou, Valéry; Aster Team

2017-04-01

Carbonate landscapes cover a significant fraction of the Earth surface, but their long-term dynamics is still poorly understood. When comparing with the situation in areas underlain by quartz-rich lithologies, where the routine use of 10Be-derived denudation rates has delivered fundamental insights on landscape evolution processes, this knowledge gap is particularly notable. Recent advances in the measurement of 36Cl and better understanding of its production pathways has opened the way to the development of a similar physically-based and quantitative analysis of landscape evolution in carbonate settings. However, beyond these methodological considerations, we still face fundamental geomorphological open questions, as for example the assessment of the importance of congruent carbonate dissolution in long-wavelength topographic evolution. Such unresolved problems concerning the relative importance of physical and chemical weathering processes lead to question the applicability of standard slope-dependent Geomorphic Transport Laws in carbonate settings. These issues have been addressed studying the geomorphological evolution of selected limestone ranges in Provence, SE France, where 36Cl concentration measurements in bedrock and stream sediment samples allow constraining denudation over 10 ka time-scale. We first identify a significant denudation contrast between the summit surface and the flanks of the ranges, pointing to a substantial contribution of gravity-driven processes to the landscape evolution, in addition to dissolution. Furthermore, a detailed analysis of the relationships between hillslope morphology and hilltop denudation allow to identify a fundamental transition between two regimes: (1) a dynamics where hillslope evolution is controlled by linear diffusive downslope regolith transport; and, (2) a domain where denudation is limited by the rate at which physical and chemical weathering processes can produce clasts and lower the hilltop. Such an abrupt transition toward a weathering-limited dynamics may prevent hillslope denudation from balancing the rate of base level fall imposed by the river network and could potentially explain the development of high local relief observed in many Mediterranean carbonate landscapes.

COMPARING FIELD PERFORMANCES OF DENUDER TECHNIQUES IN THE HIGH ARCTIC

EPA Science Inventory

A field evaluation between two annular denuder system configurations was conducted during the spring of 2003 in the marine Arctic (Ny-Ålesund, Svalbard). The IIA annular denuder system (ADS) employs a series of five single channel annular denuders, a cyclone and a filter pack to ...

Tectonic uplift and denudation rate influence soil chemical weathering intensity in a semi-arid environment, southeast Spain: physico-chemical and mineralogical evidence

NASA Astrophysics Data System (ADS)

Ameijeiras-Mariño, Yolanda; Opfergelt, Sophie; Schoonejans, Jérôme; Vanacker, Veerle; Sonnet, Philippe; Delmelle, Pierre

2015-04-01

Tectonic uplift is known to influence denudation rates. Denudation, including chemical weathering and physical erosion, affects soil production rates and weathering intensities. At topographic steady state, weathering can be transport- or weathering-limited. In the transport-limited regime, low denudation rates should lead to comparatively high weathering intensities, while in the weathering-limited case high denudation rates are associated with lower weathering intensities. Here, we test if this relationship applies to semi-arid environments where chemical weathering is generally slow. Three catchments (EST, FIL and CAB) were studied in the Internal Zone of the Betic Cordillera in southeast Spain, spanning a range of increasing uplift rates (10-170 mm/kyr) and increasing denudation rates (20-250 mm/kyr) from EST to CAB. In each catchment, two ridgetop soil profiles were sampled down to the bedrock. The three catchments have similar vegetation and climatic conditions, with precipitation of 250- 315 mm/yr and mean annual temperature of 15-17 °C. The mineralogy of the bedrock, as determined by XRD, is similar across the three catchments and is characterized by the presence of quartz, muscovite, clinochlore, biotite and plagioclase. This primary mineral assemblage is also found in the catchment soils, indicating that the soils studied derive from the same parent material. The soil clay-size fraction is dominated by kaolinite, vermiculite and illite. However, the proportions of the soil primary and secondary minerals vary between the catchment sites. The abundance of biotite decreases from CAB (14%) to EST (4%), whereas the quartz and clay contents show an opposite tendency (from 30 to 69% and 9.9 to 14.3%, respectively). Further, the abundance of vermiculite increases from CAB to EST. The results are interpreted in terms of increasing weathering intensity from CAB to EST by weathering of biotite into vermiculite and enrichment of soils on more weathering resistant quartz. Soil weathering intensity in each catchment was assessed previously [1] using three independent weathering indices: the Total Reserve in Bases (TRB = [Ca2+] + [Na+] + [K+] + [Mg2+]), soil Fed/Fet ratio (Fe-oxides/total Fe), and Cation Exchange Capacity (CEC). In agreement with the soil mineralogy, the physico-chemical analyses revealed increasing weathering intensity from CAB to EST. We postulate that the higher chemical weathering intensity in EST reflects lower denudation and uplift rates compared to CAB and therefore, soil chemical weathering intensity in this semi-arid environment may be controlled by denudation and uplift rates [1] Ameijeiras-Mariño et al, EGU 2014-9714-1

Temporal variations in the cooling and denudation history of the Hunza plutonic complex, Karakoram Batholith, revealed by 40Ar/39Ar thermochronology

NASA Astrophysics Data System (ADS)

Krol, Michael A.; Zeitler, Peter K.; Poupeau, GéRard; Pecher, Arnaud

1996-04-01

The 40Ar/39Ar thermochronology of the Late Cretaceous Hunza plutonic complex reveals an episodic cooling and denudation history for this regional-scale pluton. The 40Ar/39Ar analyses of biotites from a vertical relief section of >3200 m reveal a pulse of rapid cooling at ˜20 Ma. In the interval of 110-27 Ma, age-elevation distributions suggest denudation rates of the order of 0.02 ± 0.003 mm/yr. At ˜20 Ma, denudation rates increased significantly to 2.7 ± 0.7 mm/yr, then returned to much slower rates until 12 Ma. A second pulse of rapid cooling beginning at 12 Ma is revealed by inverse numerical modeling of multidiffusion domain alkali feldspars from a vertical section of 1700 m. Decreasing in elevation, these samples record the onset of rapid cooling at 12, 9, and 7 Ma, respectively. All of the alkali feldspars record a period of nearly isothermal conditions prior to the onset of rapid cooling when rates increased to 30°C/m.y. Assuming a geothermal gradient of 30°C/km, these cooling rates translate into denudation rates of 1.0 mm/yr. Apatite fission track analysis indicates denudation rates of 0.7 ± 0.1 mm/yr over the interval of 6.6 Ma to 2.4 Ma in agreement with the alkali feldspar data. These data suggest denudation of 2.9 ± 0.4 km since the Plio-Pleistocene. Together, the alkali feldspar and apatite data indicate that a minimum of 10 km of overburden has been removed since the mid-late Miocene. An electronic supplement of this material may be obtained on a diskette or Anonymous FTP from KOSMOS.AGU.ORG. (LOGIN to AGU's FTP account using ANONYMOUS as the username and GUEST as the password. Go to the right directory by typing CD APEND. Type LS to see what files are available. Type GET and the name of the file to get it. Finally, type EXIT to leave the system).(Paper 95TC02424, Temporal variations in the cooling and denudation history of the Hunza plutonic complex, Karakoram Batholith, revealed by 40Ar/39Ar thermochronology, M.A. Krol, P.K. Zeitler, G. Poupeau, and A. Pecher). Diskette may be ordered from American Geophysical Union, 2000 Florida Avenue, N.W., Washington, DC 20009; $15.00. Payment must accompany order.

The susceptibility of large river basins to orogenic and climatic drivers

NASA Astrophysics Data System (ADS)

Haedke, Hanna; Wittmann, Hella; von Blanckenburg, Friedhelm

2017-04-01

Large rivers are known to buffer pulses in sediment production driven by changes in climate as sediment is transported through lowlands. Our new dataset of in situ cosmogenic nuclide concentration and chemical composition of 62 sandy bedload samples from the world largest rivers integrates over 25% of Earth's terrestrial surface, distributed over a variety of climatic zones across all continents, and represents the millennial-scale denudation rate of the sediment's source area. We can show that these denudation rates do not respond to climatic forcing, but faithfully record orogenic forcing, when analyzed with respective variables representing orogeny (strain rate, relief, bouguer anomaly, free-air anomaly), and climate (runoff, temperature, precipitation) and basin properties (floodplain response time, drainage area). In contrast to this orogenic forcing of denudation rates, elemental bedload chemistry from the fine-grained portion of the same samples correlates with climate-related variables (precipitation, runoff) and floodplain response times. It is also well-known from previous compilations of river-gauged sediment loads that the short-term basin-integrated sediment export is also climatically controlled. The chemical composition of detrital sediment shows a climate control that can originate in the rivers source area, but this signal is likely overprinted during transfer through the lowlands because we also find correlation with floodplain response times. At the same time, cosmogenic nuclides robustly preserve the orogenic forcing of the source area denudation signal through of the floodplain buffer. Conversely, previous global compilations of cosmogenic nuclides in small river basins show the preservation of climate drivers in their analysis, but these are buffered in large lowland rivers. Hence, we can confirm the assumption that cosmogenic nuclides in large rivers are poorly susceptible to climate changes, but are at the same time highly suited to detect changes in orogenic forcing in their paleo sedimentary records.

In situ and denuder-based measurements of elemental and reactive gaseous mercury with analysis by laser-induced fluorescence - results from the Reno Atmospheric Mercury Intercomparison Experiment

NASA Astrophysics Data System (ADS)

Hynes, Anthony J.; Everhart, Stephanie; Bauer, Dieter; Remeika, James; Tatum Ernest, Cheryl

2017-01-01

The University of Miami (UM) deployed a sequential two-photon laser-induced fluorescence (2P-LIF) instrument for the in situ measurement of gaseous elemental mercury, Hg(0), during the Reno Atmospheric Mercury Intercomparison Experiment (RAMIX) campaign. A number of extended sampling experiments, typically lasting 6-8 h but on one occasion extending to ˜ 24 h, were conducted, allowing the 2P-LIF measurements of Hg(0) concentrations to be compared with two independently operated instruments using gold amalgamation sampling coupled with cold vapor atomic fluorescence spectroscopic (CVAFS) analysis. At the highest temporal resolution, ˜ 5 min samples, the three instruments measured concentrations that agreed to within 10-25 %. Measurements of total mercury (TM) were made by using pyrolysis to convert total oxidized mercury (TOM) to Hg(0). TOM was then obtained by difference. Variability in the ambient Hg(0) concentration limited our sensitivity for measurement of ambient TOM using this approach. In addition, manually sampled KCl-coated annular denuders were deployed and analyzed using thermal dissociation coupled with single-photon LIF detection of Hg(0). The TOM measurements obtained were normally consistent with KCl denuder measurements obtained with two Tekran speciation systems and with the manual KCl denuder measurements but with very large uncertainty. They were typically lower than measurements reported by the University of Washington (UW) Detector for Oxidized Hg Species (DOHGS) system. The ability of the 2P-LIF pyrolysis system to measure TM was demonstrated during one of the manifold HgBr2 spikes but the results did not agree well with those reported by the DOHGS system. The limitations of the RAMIX experiment and potential improvements that should be implemented in any future mercury instrument intercomparison are discussed. We suggest that instrumental artifacts make a substantial contribution to the discrepancies in the reported measurements over the course of the RAMIX campaign. This suggests that caution should be used in drawing significant implications for the atmospheric cycling of mercury from the RAMIX results.

Tectonic uplift, threshold hillslopes, and denudation rates in a developing mountain range

USGS Publications Warehouse

Binnie, S.A.; Phillips, W.M.; Summerfield, M.A.; Fifield, L.K.

2007-01-01

Studies across a broad range of drainage basins have established a positive correlation between mean slope gradient and denudation rates. It has been suggested, however, that this relationship breaks down for catchments where slopes are at their threshold angle of stability because, in such cases, denudation is controlled by the rate of tectonic uplift through the rate of channel incision and frequency of slope failure. This mechanism is evaluated for the San Bernardino Mountains, California, a nascent range that incorporates both threshold hill-slopes and remnants of pre-uplift topography. Concentrations of in situ-produced cosmogenic 10Be in alluvial sediments are used to quantify catchment-wide denudation rates and show a broadly linear relationship with mean slope gradient up to ???30??: above this value denudation rates vary substantially for similar mean slope gradients. We propose that this decoupling in the slope gradient-denudation rate relationship marks the emergence of threshold topography and coincides with the transition from transport-limited to detachment-limited denudation. The survival in the San Bernardino Mountains of surfaces formed prior to uplift provides information on the topographic evolution of the range, in particular the transition from slope-gradient-dependent rates of denudation to a regime where denudation rates are controlled by rates of tectonic uplift. This type of transition may represent a general model for the denudational response to orogenic uplift and topographic evolution during the early stages of mountain building. ?? 2007 The Geological Society of America.

Post-earthquake denudation and its impacts on ancient civilizations in the Chengdu Longmenshan region, China

NASA Astrophysics Data System (ADS)

Chen, Ningsheng; Li, Jun; Liu, Lihong; Yang, Chenglin; Liu, Mei

2018-05-01

This study characterizes significant changes in denudation and disasters in mountainous areas induced in the humid Chengdu Longmenshan region by the Wenchuan Earthquake in 2008. A study focusing on the Longxi-Baisha River Basin was conducted to investigate the amount of denudation triggered by specific flash flood and debris flow events in 2009-2014. The following results were obtained through a comparison of pre-seismic regional denudation rates and denudation characteristics of other seismically active mountain regions. (1) Regional denudation processes occurred in a wave-like process of initial increase then decline, with a peak exhibiting a hyperbolic attenuation trend. This trend indicates that the denudation rate in the Chengdu Longmenshan region is expected to return to the pre-seismic rate of 0.3 mm a-1 after 81 years. In 22 years after the earthquake (Year 2030), debris flow disasters are expected to be rare. (2) Disasters increased significantly in the Chengdu Longmenshan region after the Wenchuan earthquake, with an average of 29.5 people missing or dead per year (22 times greater than the pre-earthquake rate) and average economic losses of 192 million Yuan per year (1.6 times greater than the pre-earthquake rate). (3) The denudation process was jointly controlled by the quantities of loose solid material and precipitation after the Wenchuan earthquake. The amount of loose solid material influenced the extent of denudation, while vegetation coverage rates and soil consolidation determined the overall denudation trend in the region, and changes in precipitation led to denudation fluctuations. (4) The results can be used to analyze the relationship between the potential flash flood-debris flow disasters after earthquakes in the ancient Shu kingdom and changes in historical social settlements. The results can also be used to predict denudation processes and disaster risks from earthquakes in humid mountainous regions around the world, such as the southern slope of the Himalayas, Japan and the Taiwan mountains.

DEVELOPMENT OF AN RH -DENUDED MIE ACTIVE SAMPLING SYSTEM AND TARGETED AEROSOL CALIBRATION

EPA Science Inventory

The MIE pDR 1200 nephelometer provides time resolved aerosol concentrations during personal and fixed-site sampling. Active (pumped) operation allows defining an upper PM_2.5 particle size, however, this dramatically increases the aerosol mass passing through the phot...

Late Mesozoic and Cenozoic thermotectonic evolution of the central Brooks Range and adjacent North Slope foreland basin, Alaska: Including fission track results from the Trans-Alaska Crustal Transect (TACT)

USGS Publications Warehouse

O'Sullivan, P. B.; Murphy, J.M.; Blythe, A.E.

1997-01-01

Apatite fission track data are used to evaluate the thermal and tectonic history of the central Brooks Range and the North Slope foreland basin in northern Alaska along the northern leg of the Trans-Alaska Crustal Transect (TACT). Fission track analyses of the detrital apatite grains in most sedimentary units resolve the timing of structures and denudation within the Brooks Range, ranging in scale from the entire mountain range to relatively small-scale folds and faults. Interpretation of the results indicates that rocks exposed within the central Brooks Range cooled rapidly from paleotemperatures 110?? to 50??C during discrete episodes at ???100??5 Ma, ???60??4 Ma, and ???24??3 Ma, probably in response to kilometer-scale denudation. North of the mountain front, rocks in the southern half of the foreland basin were exposed to maximum paleotemperatures 110??C in the Late Cretaceous to early Paleocene as a result of burial by Upper Jurassic and Cretaceous sedimentary rocks. Rapid cooling from these elevated paleotemperatures also occurred due to distinct episodes of kilometer-scale denudation at ???60??4 Ma, 46??3 Ma, 35??2 Ma, and ???24??3 Ma. Combined, the apatite analyses indicate that rocks exposed along the TACT line through the central Brooks Range and foreland basin experienced episodic rapid cooling throughout the Late Cretaceous and Cenozoic in response to at least three distinct kilometer-scale denudation events. Future models explaining orogenic events in northern Alaska must consider these new constraints from fission track thermochronology. Copyright 1997 by the American Geophysical Union.

Chemical analysis of particulate and gaseous products from the monoterpene oxidation in the SAPHIR chamber during the EUCAARI campaign 2008

NASA Astrophysics Data System (ADS)

Kahnt, A.; Iinuma, Y.; Herrmann, H.; Mentel, T. F.; Fisseha, R.; Kiendler-Scharr, A.

2009-04-01

The atmospheric oxidation of monoterpenes leads to multifunctional products with lower vapour pressure. These products condense and coagulate to existing particles leading to particle formation and growth. In order to obtain better insights into the mechanisms and the importance of sources to organic aerosol, a mixture of monoterpenes was oxidised in the SAPHIR outdoor chamber during the EUCAARI campaign in 2008. The mixture was made of α-pinene, β-pinene, limonene, 3-carene and ocimene, representing a typical monoterpene emission from a boreal forest. In addition, two sesquiterpenes (α-farnesene and caryophyllene) were reacted together with the monoterpene mixture in some experiments. The VOC (volatile organic compound) mixture was reacted under tropospheric oxidation and light conditions in a prolonged time scale over two days. In the present study, a special emphasis is put on the detection of carbonyl compounds from the off-line analysis of collected filter and denuder samples from the campaign in 2008. The oxidation products which contain carbonyl groups are important first stable intermediates during the monoterpene and sesquiterpene oxidation. They react further with atmospheric oxidants to form lower volatile acidic compounds, contributing to secondary organic aerosol (SOA). Commonly used methods for the analysis of carbonyl compounds involve derivatisation steps prior to separation and subsequent UV or MS detection. In the present study, 2,4-dinitrophenylhydrazine (DNPH) was used to derivatise the extracted filter and denuder samples. The DNPH converts aldehyde- and keto-groups to stable hydrazones, which can be purified afterwards using a solid phase extraction (SPE) cartridge. The derivatised samples were analysed with HPLC/ESI-TOFMS which allowed us to determine the exact chemical formula of unknown products. In addition to known carbonyl compounds from monoterpene oxidation such as pinonaldehyde and nopinon, previously unreported molecular masses were found. These were tentatively identified as hydroxycarbonyl compounds with the molecular weight of 168 (C10H16O2) and 154 (C9H14O2 ).

Central Alpine Denudation equals Rock Uplift: Steady State or Coincidence?

NASA Astrophysics Data System (ADS)

Wittmann, H.; von Blanckenburg, F.; Kruesmann, T.; Norton, K. P.; Kubik, P. W.

2006-12-01

The Central Alps of Switzerland represent a mountain belt in which an exceptional wealth of geophysical data allows the unique test of tectono-geomorphic models. Levelling measurements show that the Central Alps are uplifting today with 0.5-1.6 mm/yr (Kahle et al. 1997). Here we present a North-South denudation rate transect through the Swiss Central Alps from a study of in situ-produced cosmogenic 10Be in river-borne quartz. Denudation rates range from 0.1 to 1.5 mm/yr. They yield a mean of 0.27+/-0.14 mm/yr for the Alpine foreland, where integration times are 2-8 ky, and of 0.9+/-0.3 mm/yr for the high crystalline Central Alps, where integration times are 0.5-1.5 ky. The measured cosmogenic nuclide-derived denudation rates are in good agreement with post-LGM lake infill rates and significantly higher than recent denudation rates from river loads. We attribute this discrepancy to differences in methodology and integration time scale. Our new rates are in the same range as denudation rates from apatite fission tracks that record denudation 3-5 Ma ago. Denudation rates correlate with hill slope in the Mittelland catchments, but they are independent of slope in the high Alps. We interprete this to mean that high Alpine landscapes are at threshold hillslope, where slopes cannot increase any further before failure occurs. In general, denudation rates are high in areas of high relief and high altitude. Importantly, good spatial agreement exists between denudation rates and recent rock uplift rates. Since all of the mentioned parameters are also highest where crustal thickness is largest, a major driving force for rock uplift and concomitant denudation is likely to be isostatic. However, given that crustal thickening of the Alps has all but ceased, the relief-forming events that set the rate of denudation and uplift must be presented by transient perturbations, such as increased erosional response to climate cycling. Thereby a quasi-steady state has been achieved in which rock uplift is balanced by denudation. This means that although the landscape is never in steady state on the short term, the conditions for long-term steady state are fulfilled nevertheless. Kahle, H., et al. (1997). Recent crustal movements, geoid and density distribution: Contribution from integrated satellite and terrestrial measurements. In O. Pfiffner (Ed.), Results of the National Research Program 20 (NRP 20), pp. 251-259, Birkhaeuser Verlag, Basel.

Three-stage nucleation and growth of Ge self-assembled quantum dots grown on partially relaxed SiGe buffer layers

NASA Astrophysics Data System (ADS)

Kim, H. J.; Zhao, Z. M.; Xie, Y. H.

2003-11-01

Three-stage nucleation and growth of Ge self-assembled quantum dots (SAQDs) on a relaxed SiGe buffer layer has been studied. Plastic relaxation of the SiGe buffer layer is associated with a network of buried 60° dislocations leading to an undulating strain field. As a result, the surface possesses three different types of sites for the nucleation and growth of Ge SAQDs: over the intersection of two perpendicular buried dislocations, over a single dislocation line, and in the region beyond one diffusion length away from any dislocation. Ge SAQDs are observed to nucleate exclusively over the dislocation intersections first, followed by over single dislocation lines, and finally in the region far away from dislocations. By increasing the Ge coverage at a slow rate, the prenucleation stage at the various sites is observed. It appears that the varying strain field has a significant effect on both the diffusion of Ge adatoms before SAQD nucleation, as well as the shape evolution of the SAQDs after they form. Moreover, two distinctly different self-assembly mechanisms are observed at different sites. There exist denuded zones free of Ge SAQDs adjacent to dislocation lines. The width of the denuded zone can be used to make direct determination of the Ge adatom diffusion lengths. The partially relaxed substrate provides a useful experimental vehicle for the in-depth understanding of the formation mechanism of SAQDs grown epitaxially in the Stranski-Krastanov growth mode.

Tufa deposits sheltered by Inland notches as indicators of Quaternary denudation rates

NASA Astrophysics Data System (ADS)

Shtober-Zisu, Nurit; Vaks, Anton; Amasha, Hani; Frumkin, Amos

2017-04-01

Denudation is the long-term sum of processes that cause the wearing away of the Earth's surface by weathering and erosion. As denudation of carbonate terrains involves mainly karstic dissolution, Israel is a natural laboratory for the study of denudation rates because of its carbonate terrain and steep precipitation gradient, ranging from >1000 mm in the north to less than 100 mm in the south. Several studies on denudation rates in Israel provide contradictory evidences. Ryb et al [1] found that denudation rates in the Mediterranean climate zone are 21±7 mm per ky, whereas Bar et al [2] showed much lower rates on the long-term scale (Oligocene-present). In this study we determined minimal ages of formation of Inland notches [3] using U-Th dating of tufa deposits developed under the notches' visors or covering notches' cavity beds. The ages of tufa were used to determine the relative slope denudation rates on Mt. Carmel (Israel) that receives annual precipitation rates of 700 mm. Inland notches are elongated concave-shape indentations that develop on the carbonate rocky cliffs of mountainous zones. These unique features formed as a result of the interaction between specific lithological and weathering factors, emphasizing the importance of climate upon denudation. Inland notches form because the most porous cavity bed retreats at a faster rate compared to the slower subaerial dissolution of the visor bed, until a critical point is reached where the visor collapses. Notches are most common in semi-arid and in Mediterranean climates, mainly in areas with annual rainfall of between 400 mm and 850 mm. Occasionally, tufa stalactites and stalagmites grow within the cavity of the notch. The Carmel tufa deposits that grew under the notches visors and on the cavity back-wall were dated by U-Th at the Geological Survey of Israel using ion exchange column chemistry and MC-ICP-MS techniques modified after Vaks et al [4]. In each notch the oldest tufa layer was dated giving the minimum age of the surface formation. Six layers from four tufa samples were dated giving ages spanning from 13,636 ± 834 ky to 37,562 ± 2,397 ky, implying that the minimal age of these notches is last glacial period, or last deglaciation. 1. Ryb, U., et al., Controls on denudation rates in tectonically stable Mediterranean carbonate terrain. Bulletin of the Geological Society of America, 2014. 126(3-4): 553-568. 2. Bar, O., et al., The uplift history of the Arabian Plateau as inferred from geomorphologic analysis of its northwestern edge. Tectonophysics, 2016. 671: 9-23. 3. Shtober-Zisu, N., et al., Inland notches: Implications for subaerial formation of karstic landforms—An example from the carbonate slopes of Mt. Carmel, Israel. Geomorphology, 2015. 229: 85-99. 4. Vaks, A., et al., Paleoclimate and location of the border between Mediterranean climate region and the Saharo-Arabian Desert as revealed by speleothems from the northern Negev Desert, Israel Earth and Planetary Science Letters, 2006. 249(3-4): 384-399.

New estimated Holocene denudation rates for non-glaciated areas in the southernmost Patagonian Andes (53°S), Chile

NASA Astrophysics Data System (ADS)

Breuer, Sonja; Kilian, Rolf; Baeza, Oscar; Arz, Helge

2010-05-01

Cenozoic denudation rates are sparsely known for the southernmost Patagonian Andes. One of the scientific approaches is to calculate long-term denudation rates based on fission track analyses. Though, these average rates comprise a long period with distinct climate conditions and very different extend of glaciation. These integrated denudation rates include extensive surface areas with different morphological, glacial and vegetational properties. In contrast, our approach is restricted to relative short Holocene periods and small catchment areas, for which the denudation and its controlling surface characteristics could be defined more precisely. Thus a more precise evaluation of the influencing parameters like climate, morphology and vegetation cover was possible. We concentrated on three restricted and nearly closed areas of denudation and accumulation. In those catchments we determined the sediment masses of lakes, based on sediment drilling, echosounding and computer based interpolation of the siliciclastic sediment masses. These masses were transferred to the denudation areas which have been characterised and measured by remote sensing. The westernmost Tamar Lake is located on the Tamar Island in the western part of the Magellan Strait, where the annual precipitation is about 4,000 mm. The catchment area has a dense vegetation cover. The lake surrounding slopes reach an elevation of 400 m a.s.l and they are up to 60° steep. The calculated denudation rate for this catchment is about 2.56 mm/ka, which represents a minimum value, because the postglacial weathering horizon is only partly removed into the lake. The highest elevated lake Muy Profundo (500 m a.s.l.) possesses a denudation area with a nearly vegetation-free zone up to 750 m a.s.l. within the Patagonian Batholith. The catchment area of this lake is characterised by a roche moutonnée landform with steep slopes and active fracture zones. The precipitation varies between 5,000 and 8,000 mm/a. The denudation rates of the catchment amount to 0.42 mm/ka. Despite the high precipitation and the exposed position this denudation rate is unexpectedly low. Along the active fracture zones a stronger denudation could be observed by the occurrence of restricted gullies. The removed predominantly coarse clastic material is stored in alluvial cones and not included in our mass balance. The elevation of the catchment of the easternmost Chandler does not exceed 200 m a.s.l. and the area is characterised by a moderate relief with relatively flat slopes. The roche moutonnée landscape is interspersed with tracts of peat land and Magellanic rainforest. The precipitation ranges between 3,500 and 5,000 mm/a. Circulating acid soil water cause an intense chemical weathering and formed a 10-20 cm thick weathering horizon at the interface between bedrock and peaty soil. Due to the sediment core and the echosound stratigraphy, the denudation could be determined for two periods of time. The 2,040 cal. a BP tephra layer of the Mt. Burney volcano is the most distinct reflector in the echosound data. Therefore it was used as a sedimentation boundary. The denudation rates for the period 12,100 to ~2,000 and for the last 2000 years are very similar with ~2.55 mm/ka. On the basis of e.g. Ti/U enrichment in the weathering horizon, we conclude that the chemical denudation is very important in areas with vegetation cover in the superhumid Andes. In a long-term perspective, the relatively high denudation rates of low elevated peat land compared to the exposed rock surfaces may further increase the relief even during interglacial periods, like the Holocene. On the basis of our results we could state that the precipitation plays only a subordinated role as a control mechanism concerning the denudation in ice-free, but low temperate areas of the Patagonian Andes.

Endothelial Cell Morphology and Migration are Altered by Changes in Gravitational Fields

NASA Technical Reports Server (NTRS)

Melhado, Caroline; Sanford, Gary; Harris-Hooker, Sandra

1997-01-01

Endothelial cell migration is important to vascular wall regeneration following injury or stress. However, the mechanism(s) governing this response is not well understood. The microgravity environment of space may complicate the response of these cells to injury. To date, there are no reports in this area. We examined how bovine aortic (BAEC) and pulmonary (BPEC) endothelial cells respond to denudation injury under hypergravity (HGrav) and simulated microgravity (MGrav), using image analysis. In 10% FBS, the migration of confluent BAEC and BPEC into the denuded area was not affected by HGrav or MGrav. However, in low FBS (0.5%), signficantly retarded migration under MGrav, and increased migration under HGrav was found. MGrav also decreased the migration of postconfluent BPEC while HGrav showed no difference. Both MGrav and HGrav strongly decreased the migration of postconfluent BAEC. Also, both cell lines showed significant morphological changes by scanning electron microscopy. These studies indicate that endothelial cell function is affected by changes in gravity.

Annular denuders for use in global climate and stratospheric measurements of acidic gases and particles

NASA Technical Reports Server (NTRS)

Stevens, Robert K.

1991-01-01

Measurements of acidic and basic gases that coexist with fine particle (less than 2.5 micron) may be useful for determining the impact of these species on global climate changes and determining species that influence stratospheric ozone levels. Annular denuders are well suited for this purpose. A new concentric annular denuder system, consisting of a three channel denuder, a Teflon coated cyclone preseparator, and a multistage filter pack was developed, evaluated, and shown to provide reliable atmospheric measurements of SO2, HNO2, HNO3, NH3, SO4(=), NH4(+), NO3(-), and H(+). For example, the precision of the annular denuder for the ambient measurements of HNO3 and nitrates at concentrations between 0.1 to 3 microgram/cu m was + or - 12 and 16 pct., respectively. The 120 x 25 mm three channel denuder is encased in a stainless steel sheath and has annular spaces that are 1 mm wide. This design was shown to have nearly identical capacity for removal of SO2 as conventional 210 x 25 mm single channel denuder configurations. The cyclone preseparator was designed and tested to have a D sub 50 cutoff diameter of 2.5 micron and minimal retention of HNO3.

Evaluation of the KCl Denuder Method for Gaseous Oxidized Mercury using HgBr2 at an In-Service AMNet Site

NASA Astrophysics Data System (ADS)

McClure, Crystal

During the summer of 2013, we examined the performance of KCl-coated denuders for measuring gaseous oxidized mercury (GOM) by calibrating with a known source of GOM (i.e., HgBr2) at the North Birmingham SouthEastern Aerosol Research and Characterization (SEARCH) site. We found that KCl-coated denuders have near 95% collection efficiency for HgBr2 in zero air (i.e., air scrubbed of mercury and ozone). However, in ambient air, the efficiency of KCl-coated denuders in capturing HgBr2 dropped to 20-54%. We also found that absolute humidity and ozone each demonstrate a significant inverse correlation with HgBr2 recovery in ambient air. Subsequent laboratory tests with HgBr2 and the KCl-coated denuder show that ozone and absolute humidity cause the release of gaseous elemental Hg from the denuder and thus appear to explain the low recovery in ambient air. Based on these findings, we infer that the KCl denuder method underestimates atmospheric GOM concentrations. A calibration system is needed to accurately measure GOM. The system described in this paper for HgBr2 could be implemented with existing mercury speciation instrumentation and this would improve our knowledge of the response to one potentially important GOM compound.

Lateral thinking: 2-D interpretation of thermochronology in convergent orogenic settings

NASA Astrophysics Data System (ADS)

Batt, Geoffrey E.; Brandon, Mark T.

2002-05-01

Lateral motion of material relative to the regional thermal and kinematic frameworks is important in the interpretation of thermochronology in convergent orogens. Although cooling ages in denuded settings are commonly linked to exhumation, such data are not related to instantaneous behavior but rather to an integration of the exhumation rates experienced between the thermochronological 'closure' at depth and subsequent exposure at the surface. The short spatial wavelength variation of thermal structure and denudation rate typical of orogenic regions thus renders thermochronometers sensitive to lateral motion during exhumation. The significance of this lateral motion varies in proportion with closure temperature, which controls the depth at which isotopic closure occurs, and hence, the range of time and length scales over which such data integrate sample histories. Different chronometers thus vary in the fundamental aspects of the orogenic character to which they are sensitive. Isotopic systems with high closure temperature are more sensitive to exhumation paths and the variation in denudation and thermal structure across a region, while those of lower closure temperature constrain shorter-term behaviour and more local conditions. Discounting lateral motion through an orogenic region and interpreting cooling ages purely in terms of vertical exhumation can produce ambiguous results because variation in the cooling rate can result from either change in kinematics over time or the translation of samples through spatially varying conditions. Resolving this ambiguity requires explicit consideration of the physical and thermal framework experienced by samples during their exhumation. This can be best achieved through numerical simulations coupling kinematic deformation to thermal evolution. Such an approach allows the thermochronological implications of different kinematic scenarios to be tested, and thus provides an important means of assessing the contribution of lateral motion to orogenic evolution.

Weathering-limited hillslope evolution in carbonate landscapes

NASA Astrophysics Data System (ADS)

Godard, Vincent; Ollivier, Vincent; Bellier, Olivier; Miramont, Cécile; Shabanian, Esmaeil; Fleury, Jules; Benedetti, Lucilla; Guillou, Valéry; Aster Team

2016-07-01

Understanding topographic evolution requires integrating elementary processes acting at the hillslope scale into the long-wavelength framework of landscape dynamics. Recent progress has been made in the quantification of denudation of eroding landscapes and its links with topography. Despite these advances, data is still sparse in carbonate terrain, which covers a significant part of the Earth's surface. In this study, we measured both long-term denudation rates using in situ-produced 36Cl concentrations in bedrock and regolith clasts and surface convexity at 12 sites along ridges of the Luberon carbonate range in Provence, Southeastern France. Starting from ∼30 mm/ka for the lowering of the summit plateau surface, denudation linearly increases with increasing hilltop convexity up to ∼70 mm/ka, as predicted by diffusive mass transport theory. Beyond this point denudation rates appear to be insensitive to the increase in hilltop convexity. We interpret this constant denudation as indicating a transition from a regime where hillslope evolution is primarily controlled by diffusive downslope regolith transport, toward a situation in which denudation is limited by the rate at which physical and chemical weathering processes can produce clasts and lower the hilltop. Such an abrupt transition into a weathering-limited dynamics may prevent hillslope denudation from balancing the rate of base level fall imposed by the river network and could potentially explain the development of high local relief in many Mediterranean carbonate landscapes.

Relief evolution of the Continental Rift of Southeast Brazil revealed by in situ-produced 10Be concentrations in river-borne sediments

NASA Astrophysics Data System (ADS)

Salgado, André Augusto Rodrigues; Rezende, Eric de Andrade; Bourlès, Didier; Braucher, Régis; da Silva, Juliana Rodrigues; Garcia, Ricardo Alexandrino

2016-04-01

This study aims to quantify the denudation dynamics of the Brazilian passive margin along a segment of the Continental Rift of Southeast Brazil. The denudation rates of 30 basins that drain both horsts of the continental rift, including the mountain ranges of the Serra do Mar (seaside horst); and the Serra da Mantiqueira (continental horst); were derived from 10Be concentrations measured in sand-sized river sediment. The mean denudation rate ranges from 9.2 m Ma-1 on the plateau of the Serra do Mar to 37.1 m Ma-1 along the oceanic escarpment of the Serra do Mar. The seaward-facing scarps of both mountain ranges exhibit mean denudation rates that are approximately 1.5 times those of the inland-facing scarps. The escarpments of the horst nearer to the ocean (Serra do Mar) exhibit higher denudation rates (mean 30.2 m Ma-1) than the escarpments of the continental horst (Serra da Mantiqueira) (mean 16.5 m Ma-1). The parameters that impact these denudation rates include the catchment relief, the slope gradient, the rock and the climate. The incongruent combination of a mountainous landscape and moderate to low 10Be-based denudation rates averaging at ∼20 m Ma-1 suggests a reduction in intraplate tectonic activity beginning in the Middle Quaternary or earlier.

Comparison among filter-based, impactor-based and continuous techniques for measuring atmospheric fine sulfate and nitrate

NASA Astrophysics Data System (ADS)

Nie, Wei; Wang, Tao; Gao, Xiaomei; Pathak, Ravi Kant; Wang, Xinfeng; Gao, Rui; Zhang, Qingzhu; Yang, Lingxiao; Wang, Wenxing

2010-11-01

Filter-based methods for sampling aerosols are subject to great uncertainty if the gas-particle interactions on filter substrates are not properly handled. Sampling artifacts depend on both meteorological conditions and the chemical mix of the atmosphere. Despite numerous of studies on the subject, very few have evaluated filter-based methods in the Asian environments. This paper reports the results of a comparison of the performances of two filter-based samplers, including a Thermo Anderson Chemical Speciation Monitor (RAAS) and a honeycomb denuder filter-pack system, a Micro Orifice Uniform Deposit Impactor (MOUDI) and a real-time ambient ion monitor (AIM, URG9000B) in measuring atmospheric concentrations of PM 2.5 sulfate and nitrate. Field studies were conducted at an urban site in Jinan, Shandong province, during the winter of 2007 and at a rural site near Beijing in the summer of 2008. The AIM was first compared with the honeycomb denuder filter-pack system which was considered to have minimal sampling artifacts. After some modifications made to it, the AIM showed good performance for both sulfate and nitrate measurement at the two sites and was then used to evaluate other instruments. For the un-denuded RAAS, the extent of sampling artifacts for nitrate on quartz filters was negligible, while that on Teflon filters was also minimal at high nitrate concentrations (>10 μgm -3); however, loss through evaporation was significant (˜75%) at low nitrate concentrations under hot summer conditions. The MOUDI using aluminum substrates suffered a significant loss of nitrate (50-70%) under summer conditions due to evaporation. Considering that the aluminum substrates are still being widely used to obtain size-resolved aerosol compositions because of their low cost and accurate mass weighed, caution should be taken about the potential significant under determination of semi-volatile components such as ammonium nitrate.

Improved measurement of carbonaceous aerosol in Beijing, China: intercomparison of sampling and thermal-optical analysis methods

NASA Astrophysics Data System (ADS)

Cheng, Y.; He, K. B.; Duan, F. K.; Zheng, M.; Ma, Y. L.; Tan, J. H.; Du, Z. Y.

2010-06-01

The sampling artifacts (both positive and negative) and the influence of thermal-optical methods (both charring correction method and the peak inert mode temperature) on the split of organic carbon (OC) and elemental carbon (EC) were evaluated in Beijing. The positive sampling artifact constituted 10% and 23% of OC concentration determined by the bare quartz filter during winter and summer, respectively. For summer samples, the adsorbed gaseous organics were found to continuously evolve off the filter during the whole inert mode when analyzed by the IMPROVE-A temperature protocol. This may be due to the oxidation of the adsorbed organics during sampling (reaction artifact) which would increase their thermal stability. The backup quartz approach was evaluated by a denuder-based method for assessing the positive artifact. The quartz-quartz (QBQ) in series method was demonstrated to be reliable, since all of the OC collected by QBQ was from originally gaseous organics. Negative artifact that could be adsorbed by quartz filter was negligible. When the activated carbon impregnated glass fiber (CIG) filter was used as the denuded backup filter, the denuder efficiency for removing gaseous organics that could be adsorbed by the CIG filter was only about 30%. EC values were found to differ by a factor of about two depending on the charring correction method. Influence of the peak inert mode temperature was evaluated based on the summer samples. The EC value was found to continuously decrease with the peak inert mode temperature. Premature evolution of light absorbing carbon began when the peak inert mode temperature was increased from 580 to 650 °C; when further increased to 800 °C, the OC and EC split frequently occurred in the He mode, and the last OC peak was characterized by the overlapping of two separate peaks. The discrepancy between EC values defined by different temperature protocols was larger for Beijing carbonaceous aerosol compared with North America and Europe, perhaps due to the higher concentration of brown carbon in Beijing aerosol.

Continuous and large sediment supply in a steep landslide scar, Southern Japanese Alps

NASA Astrophysics Data System (ADS)

Nishii, Ryoko; Imaizumi, Fumitoshi; Daimaru, Hiromu; Murakami, Wataru

2018-07-01

Continuous sediment supply in the Aka-kuzure landslide scar, in the tectonically active alpine Southern Japanese Alps, was investigated using airborne light detection and ranging data in 2000, 2003, 2007 and 2012. In addition, we focused on the spatial variability of denudation patterns based on topographical analyses using DEMs. Denudation volume for the past 12 years reached about 106 m3 and mean annual denudation rate ranged from 0.25 to 0.31 m/yr. Topographical analyses revealed that sediment supply in the scar consists of a combination of two denudation types, sporadic-deep and wide-thin. These denudation types have different roles in the topographical development of the landslide scar. Sporadic-deep type supplies less volume than wide-thin type but still contributes to channel development, as it mainly occurs on lower-order streams and tends to change the convex slope into a concave slope. In contrast, although denudation depth of the wide-thin type is thin, the area affected by this type extends to the whole landslide scar. Consequently, the wide-thin type accounts for most of the total volume lost, for which detachment by frost shattering is suggested as an important role.

Post-Gondwana geomorphic evolution of southwestern Africa: Implications for hte controls on landscape development from observations and numerical experiments

NASA Technical Reports Server (NTRS)

Gilchrist, Alan R.; Kooi, Henk; Beaumont, Christopher

1994-01-01

The relationship between morphology and surficial geology is used to quantify the denudation that has occurred across southwestern Africa sicne the fragmentation of Gondwana during the Early Mesozoic. Two main points emerge. Signficant denudation, of the order of kilometers, is widespread except in the Kalahari region of the continental interior. The denudation is systematically distributed so that the continental exterior catchment, draining directly to the Cape basin, is denuded to a greater depth than the interior catchment inland of the Great Escarpment. The analysis also implies tha the majority of the denudation occurred before the beginning of the Cenozoic for both teh exerior and interior catchments. Existing models of landscape development are reviewed, and implications of the denudation chronology are incorporated into a revised conceptual model. This revision implies tha thte primary effect of rifting on the subsequent landscape evolution is that it generates two distinct drainage regimes. A marginal upwarp, or rift flank uplift, separates rejuvenated rivers that drain into the subsiding rift from rivers in the continetal interior that are deflected but not rejuvenated. The two catchments evolve independently unless they are integrated by breaching of hte marginal upwarp. If this occurs, the exterior baselevel is communicated to the interior catchment that is denuded accordingly. Denudation rates generally decrease as the margin evolves, and this decrease is reinforced by the exposure of substrate that is resistant to denudation and/or a change to a more arid climate. The observations do not reveal a particular style of smaller-scale landscape evolution, sucha s escarpment retreat, that is responsible for the differential denudation across the region. It is proposed that numerical model experiments, which reflect the observational insights at the large scale, may identify the smaller-scale controls on escarpment development if the model and natural systems are analogous. Four numerical experiments are presented in which the roles of antecedent topography, resistant substrate, climte change, and lowering the baselevel of the interior catchment are investigated for an initially high elevation margin bordered by an escarpment. The model results suggest several styles of landscape evolution that are compatible with the observations. Escarpments may retreat in a regular manner, but they also degrade and are destroyed, only to reform at the drainage divide between exterior and interior catchments.

Recent topographic evolution and erosion of the deglaciated Washington Cascades inferred from a stochastic landscape evolution model

NASA Astrophysics Data System (ADS)

Moon, S.; Shelef, E.; Hilley, G. E.

2013-12-01

The Washington Cascades is currently in topographic and erosional disequilibrium after deglaciation occurred around 11- 17 ka ago. The topography still shows the features inherited from prior alpine glacial processes (e.g., cirques, steep side-valleys, and flat valley bottoms), though postglacial processes are currently denuding this landscape. Our previous study in this area calculated the thousand-year-timescale denudation rates using cosmogenic 10Be concentration (CRN-denudation rates), and showed that they were ~ four times higher than million-year-timescale uplift rates. In addition, the spatial distribution of denudation rates showed a good correlation with a factor-of-ten variation in precipitation. We interpreted this correlation as reflecting the sensitivity of landslide triggering in over-steepened deglaciated topography to precipitation, which produced high denudation rates in wet areas that experienced frequent landsliding. We explored this interpretation using a model of postglacial surface processes that predicts the evolution of the topography and denudation rates within the deglaciated Washington Cascades. Specifically, we used the model to understand the controls on and timescales of landscape response to changes in the surface process regime after deglaciation. The postglacial adjustment of this landscape is modeled using a geomorphic-transport-law-based numerical model that includes processes of river incision, hillslope diffusion, and stochastic landslides. The surface lowering due to landslides is parameterized using a physically-based slope stability model coupled to a stochastic model of the generation of landslides. The model parameters of river incision and stochastic landslides are calibrated based on the rates and distribution of thousand-year-timescale denudation rates measured from cosmogenic 10Be isotopes. The probability distribution of model parameters required to fit the observed denudation rates shows comparable ranges from previous studies in similar rock types and climatic conditions. The calibrated parameters suggest that the dominant sediment source of river sediments originates from stochastic landslides. The magnitude of landslide denudation rates is determined by failure density (similar to landslide frequency), while their spatial distribution is largely controlled by precipitation and slope angles. Simulation results show that denudation rates decay over time and take approximately 130-180 ka to reach steady-state rates. This response timescale is longer than glacial/interglacial cycles, suggesting that frequent climatic perturbations during the Quaternary may prevent these types of landscapes from reaching a dynamic equilibrium with postglacial processes.

INTEGRATED AND REAL-TIME DIFFUSION DENUDER SAMPLE FOR PM2.5. (R825367)

EPA Science Inventory

Abstract

Particulate matter (PM) is a complex mixture of stable condensed phases, adsorbed or dissolved gases, and semi-volatile materials, i.e. compounds that transfer between the gas and condensed phases. Fine particles in both rural and urban environments contain su...

Thermochronologic constraints on post-Paleozoic tectonic evolution of the central Transantarctic Mountains, Antarctica

NASA Astrophysics Data System (ADS)

Fitzgerald, Paul G.

1994-08-01

Built upon the roots of a compressive orogenic belt of late Proterozoic-early Paleozoic age and once adjacent to North America, the present-day Transantarctic Mountains (TAM) represent a rift flank, resulting from episodic uplift in the Cretaceous and Cenozoic. Fault blocks are discernible in present-day topography and subglacial morphology. Fission track results give information on differential block movement (uplift and denudation) and are important in constraining models for the uplift of the range. Apatite fission track thermochronology on samples collected from the central TAM record a complex thermotectonic history for this region over the past 350 m.y. Apatite ages in the Miller Range vary from ˜250 to ˜350 Ma and are from an exhumed apatite partial annealing zone formed following cooling of Cambro-Ordovician granitoids. A period of Cretaceous denudation (≲2 km), beginning at ˜115 Ma, is recorded at Moody Nunatak on the inland side of the TAM. Near the coast, samples along the Beardmore Glacier record rapid cooling indicative of denudation initiated in the early Cenozoic (˜50 Ma). The amount of uplift ˜70 km inland of the coast in the Queen Alexandra Range since the early Cenozoic is ˜7 km, with the likelihood of an additional ˜3 km at the coast. Eastward facing topographic escarpments in the Queen Alexandra Range mark the likely position of steeply dipping normal faults, which offset the apatite ages. Apatite ages on the east side of the Beardmore Glacier mouth are generally younger (average 27 Ma) than on the west side (average 33 Ma), reflecting greater denudation. Assumptions made regarding the use of an assumed paleogeothermal gradient are tested with available geologic evidence. The fission track data neither conflict with nor confirm paleobotanical evidence from the Sirius Group in the central TAM which suggests significant surface uplift (2-3 km) of the TAM since the Pliocene. Results build upon the available fission track database along the TAM and emphasize the subtle variability of uplift along the TAM due to episodic uplift involving differential block movements.

Chemical denudation and the role of sulfide oxidation at Werenskioldbreen, Svalbard

NASA Astrophysics Data System (ADS)

Stachnik, Łukasz; Majchrowska, Elżbieta; Yde, Jacob C.; Nawrot, Adam P.; Cichała-Kamrowska, Katarzyna; Ignatiuk, Dariusz; Piechota, Agnieszka

2016-07-01

This study aims to determine the rate of chemical denudation and the relationships between dominant geochemical reactions operating in the proglacial and subglacial environments of the polythermal glacier Werenskioldbreen (SW Svalbard) during an entire ablation season. Water sampling for major ion chemistry was performed at a proglacial hydrometric station and from subglacial outflows from May to September 2011. These data were combined with measurements of discharge and supraglacial ablation rates. The slopes and intercepts in best-fit regressions of [*Ca2+ + *Mg2+ vs. *SO42-] and [HCO3- vs. *SO42-] in meltwater from ice-marginal subglacial channels were close to the stoichiometric parameters of sulfide oxidation and simple hydrolysis coupled to carbonate dissolution (*concentrations corrected for input of sea-salt). This shows that these relationships predominates the meltwater chemistry. Our findings also show that sulfide oxidation is a better indicator of the configuration of subglacial drainage systems than, for instance, Na+ and K+. In the proglacial area and in sub-artesian outflows, the ion associations represent sulfide oxidation but other processes such as ion exchange and dissolution of Ca and Mg efflorescent salts may also contribute to the solute variations. These processes may cause enhanced fluxes of Ca2+ and HCO3- from glacierized basins during the early ablation and peak flow seasons as the proglacial salts re-dissolve. The overall chemical denudation rate in the basin for 2011 (ranging from 1601 to 1762 meq m-2 yr-1 (121.9 to 132.2 t km-2 yr-1)) was very high when compared to other Svalbard valley glaciers suggesting that the high rate of chemical denudation was mostly caused by the high rates of discharge and ablation. Chemical weathering intensities (876 and 964 meq m-3 yr-1) exceeded previously reported intensities in Svalbard.

Coupling data from U-series and 10Be CRN to evaluate soil steady-state in the Betic Cordillera

NASA Astrophysics Data System (ADS)

Schoonejans, Jerome; Vanacker, Veerle; Opfergelt, Sophie; Granet, Mathieu; Chabaux, François

2015-04-01

The regolith mantel is produced by weathering of bedrock through physical and biochemical processes. At the same time, the upper part of the regolith is eroded by gravity mass movements, water and wind erosion. Feedback's between production and erosion of soil material are important for soil development, and are essential to reach long-term steady-state in soil chemical and physical properties. Nowadays, long-term denudation rates of regolith can be quantified by using in-situ cosmogenic nuclides (CRN). If the soil thickness remains constant over sufficiently long time, soil production rates can be determined. However, the a priori assumption of long-term steady-state can be questionable in highly dynamic environments. In this study, we present analytical data from two independent isotopic techniques, in-situ cosmogenic nuclides and Uranium series disequilibrium. The disequilibrium of Uranium isotopes (238U, 234U, 230Th, 226Ra) is an alternative method that allows assessing soil formation rates through isotopic analysis of weathering products. Nine soil profiles were sampled in three different mountain ranges of the Betic Cordillera (SE Spain): Sierra Estancias, Filabres, Cabrera. All soils overly fractured mica schist and are very thin (< 60cm). In each soil profile, we sampled 4 to 6 depth slices in the soil profile, the soil-bedrock interface and (weathered) bedrock. Three of the nine soil profiles were sampled for U-series isotope measurements at EOST (University of Strasbourg). The surface denudation rates (CRN) are about the same in the Sierra Estancias and Filabres (26 ± 10 mm/ky) and increase up to 103 ± 47 mm/ky in the Sierra Cabrera. The spatial variation in soil denudation rates is in agreement with the variation in catchment-wide denudation rates presented by Bellin et al. (2014) which present the highest rates in the Sierra Cabrera (104-246mm/kyr). Moreover it roughly coincides with the pattern of long-term exhumation of the Betic Cordillera. Results from first simulations of the U-series disequilibrium model rather suggest that soil production rates are of the same order of magnitude in the Sierra Estancias and Cabrera. In the Sierra Filabres, the U-series disequilibrium in the depth profile do not respect the hypotheses of the model therefore no rates of soil production could be constrain for this profile. Thanks to the coupling of the two isotopic datasets the long term soil development will be explored in two profiles. This study highlights that comparison and combination of analytical techniques is useful to further unravel the mechanisms of chemical and physical weathering in such dynamic environments. Bellin, N., Vanacker, V., and Kubik, P. W., 2014, Denudation rates and tectonic geomorphology of the Spanish Betic Cordillera: Earth and Planetary Science Letters, v. 390, p. 19-30.

Determination of predevelopment denudation rates of an agricultural watershed (Cayaguas River, Puerto Rico) using in-situ-produced 10Be in river-borne quartz

USGS Publications Warehouse

Brown, E.T.; Stallard, R.F.; Larsen, M.C.; Bourles, D.L.; Raisbeck, G.M.; Yiou, F.

1998-01-01

Accurate estimates of watershed denudation absent anthropogenic effects are required to develop strategies for mitigating accelerated physical erosion resulting from human activities, to model global geochemical cycles, and to examine interactions among climate, weathering, and uplift. We present a simple approach to estimate predevelopment denudation rates using in-situ-produced cosmogenic 10Be in fluvial sediments. Denudation processes in an agricultural watershed (Cayaguas River Basin, Puerto Rico) and a matched undisturbed watershed (Icacos River Basin) were compared using 10Be concentrations in quartz for various size fractions of bed material. The coarse fractions in both watersheds bear the imprint of long subsurface residence times. Fine material from old shallow soils contributes little, however, to the present-day sediment output of the Cayaguas. This confirms the recent and presumably anthropogenic origin of the modern high denudation rate in the Cayaguas Basin and suggests that pre-agricultural erosional conditions were comparable to those of the present-day Icacos.

Validation of ammonia diffusive and active samplers in a controlled atmosphere test facility using traceable Primary Standard Gas Mixtures

NASA Astrophysics Data System (ADS)

Martin, Nicholas A.; Ferracci, Valerio; Cassidy, Nathan; Hook, Josh; Battersby, Ross M.; Tang, Yuk S.; Stevens, Amy C. M.; Jones, Matthew R.; Braban, Christine F.; Gates, Linda; Hangartner, Markus; Stoll, Jean-Marc; Sacco, Paolo; Pagani, Diego; Hoffnagle, John A.

2017-04-01

Intensive animal farming, the increased use of fertilizers, and certain industrial processes are believed to be responsible for the observed increases in the amount fraction of ammonia (NH3) found in Europe. NH3 contributes to eutrophication and acidification of land and freshwater, potentially leading to a loss of biodiversity and undesirable changes to the ecosystem. It also contributes to the formation of secondary particulate matter (PM) formation, which is associated with poor air quality and adverse health outcomes. Measurements of ambient ammonia are principally carried out with low-cost diffusive samplers or by active sampling with denuders, with each method delivering time-integrated values over the monitoring period. However, such techniques have not yet been extensively validated. The goal of this work was to provide improvements in the metrological traceability through the determination of NH3 diffusive sampling rates. Five different designs of commercial diffusive samplers (FSM Radiello radial sampler, Gradko diffusion tube, Gradko DIFRAM-400, Passam ammonia sampler, and CEH ALPHA sampler) were employed, together with a pumped denuder sampler (CEH DELTA denuder) for comparison. All devices were simultaneously exposed for either 28 days or 14 days (dependent on sampler type) in a controlled atmosphere test facility (CATFAC) containing traceable amount fractions of humidified ammonia using new stable ammonia Primary Standard Gas Mixtures developed by gravimetry at NPL, under a wide range of conditions that are relevant to ambient monitoring. Online continuous monitoring of the ammonia test atmospheres was carried out by extractive sampling, employing a calibrated cavity ring-down spectrometer, which had been modified to account for cross interference by water vapour. Each manufacturer extracted the captured ammonia on the exposed samplers in the form of ammonium (NH4+) using their own accredited traceable wet chemical techniques, and then reported data based on their historical diffusive sampling rates. There was considerable variation in the results, which demonstrated the need for such validation work to be carried out. We report new measurements of the NH3 sampling rates determined in the CATFAC, which can be applied to improve the reliability of measurements in the field.

Addressing the contribution of climate and vegetation cover on hillslope denudation, Chilean Coastal Cordillera (26°-38°S)

NASA Astrophysics Data System (ADS)

Schaller, M.; Ehlers, T. A.; Lang, K. A. H.; Schmid, M.; Fuentes-Espoz, J. P.

2018-05-01

The Earth surface is modulated by interactions among tectonics, climate, and biota. The influence of each of these factors on hillslope denudation rates is difficult to disentangle. The Chilean Coastal Cordillera offers a strong climate and vegetation gradient from arid and unvegetated in the North to humid and vegetated in the South. A similar (convergent) plate tectonic boundary lies to the West of the Coastal Cordillera. We present eight depth profiles analyzed for in situ-produced cosmogenic 10Be in four study areas. These profiles reveal denudation rates of soil-mantled hillslopes and the depth of mobile layers. Depth profiles were investigated from both S- and N-facing mid-slope positions. Results indicate the depth of the mobile layers in the four study areas increase from N to S in latitude. When mixing is present in the mobile layers they are completely mixed. In the S- and N-facing hillslopes of each study area, mid-slope positions do not show a systematic change in depth of the mobile layers nor in denudation rates based on cosmogenic depth profiles. From N to S in latitude, modelled denudation rates of hillslopes increase from ∼0.46 to ∼5.65 cm/kyr and then decrease to ∼3.22 cm/kyr in the southernmost, highest vegetation cover, study area. Calculated turnover times of soils decrease from ∼30 to ∼11 kyr and then increase to ∼22 kyr. In this work, the increasing denudation rates are attributed to increasing mean annual precipitation from N to S. However, despite the ongoing increase in precipitation from N to S, the denudation rate in the southernmost location does not continue to increase due to the protective nature of increasing vegetation cover. This indicates a vegetation induced non-linear relationship with denudation rates.

Earthquakes drive focused denudation along a tectonically active mountain front

NASA Astrophysics Data System (ADS)

Li, Gen; West, A. Joshua; Densmore, Alexander L.; Jin, Zhangdong; Zhang, Fei; Wang, Jin; Clark, Marin; Hilton, Robert G.

2017-08-01

Earthquakes cause widespread landslides that can increase erosional fluxes observed over years to decades. However, the impact of earthquakes on denudation over the longer timescales relevant to orogenic evolution remains elusive. Here we assess erosion associated with earthquake-triggered landslides in the Longmen Shan range at the eastern margin of the Tibetan Plateau. We use the Mw 7.9 2008 Wenchuan and Mw 6.6 2013 Lushan earthquakes to evaluate how seismicity contributes to the erosional budget from short timescales (annual to decadal, as recorded by sediment fluxes) to long timescales (kyr to Myr, from cosmogenic nuclides and low temperature thermochronology). Over this wide range of timescales, the highest rates of denudation in the Longmen Shan coincide spatially with the region of most intense landsliding during the Wenchuan earthquake. Across sixteen gauged river catchments, sediment flux-derived denudation rates following the Wenchuan earthquake are closely correlated with seismic ground motion and the associated volume of Wenchuan-triggered landslides (r2 > 0.6), and to a lesser extent with the frequency of high intensity runoff events (r2 = 0.36). To assess whether earthquake-induced landsliding can contribute importantly to denudation over longer timescales, we model the total volume of landslides triggered by earthquakes of various magnitudes over multiple earthquake cycles. We combine models that predict the volumes of landslides triggered by earthquakes, calibrated against the Wenchuan and Lushan events, with an earthquake magnitude-frequency distribution. The long-term, landslide-sustained "seismic erosion rate" is similar in magnitude to regional long-term denudation rates (∼0.5-1 mm yr-1). The similar magnitude and spatial coincidence suggest that earthquake-triggered landslides are a primary mechanism of long-term denudation in the frontal Longmen Shan. We propose that the location and intensity of seismogenic faulting can contribute to focused denudation along a high-relief plateau margin.

Preliminary study of the distribution of gaseous mercury species in the air of Guiyang city, China

NASA Astrophysics Data System (ADS)

Shang, L.; Feng, X.; Zheng, W.; Yan, H.

2003-05-01

Total gaseous mercury (TGM) in ambient air consists of Hg^0 and reactive gaseous mercury (RGM) in general. Although RGM only constitutes a small portion of TGM in the air, it contributes the most to both dry and wet deposition of mercury from the atmosphere. TGM and RGM concentrations in ambient air at one site of Guiyang City were determined in March 2002. TGM concentrations were monitored using an automated mercury vapor analyzer Tekran2537A, and RGM in ambient air was sampled using KCI coated tubular denuders. The sampled RGM denuders were analyzed using thermal desorption coupled with CVAFS detection. The average concentrations of TGM and RGM are 7.09 ng m^{-3} and 37.5pg m^{-3} respectively during the sampling period. The primary anthropogenic source for both Hg^0 and RGM is coal combustion in the study area. TGM concentrations are significantly elevated comparing to the global background values, whereas RGM concentrations are only slightly higher than the reported values in remote areas in Europe and US. RGM only constitutes 0.5% ofTGM in the air at the sampling period. There is a significant negative correlation between RGM concentration and relative humidity (RH), with a coefficient correlation of 0.39 (α<0.01). High relative humidity during the sampling is responsible for the relatively low RGM concentrations observed.

A Novel Treatment of Denuded Areas in Newborns: A Report of 2 Successful Cases

PubMed Central

Milanés, Felipe; Vergara, Teresa; Lara, Laura; Duran, Andres; Robayo, Adriana

2015-01-01

Summary: Covering denuded areas in the extremes of life is challenging for the plastic surgeon. In newborns, this becomes a greater challenge because of the immaturity of all of their systems, making any injury a potential risk for death. We present in this case report a successful treatment of 2 cases covered with cultured autologous keratinocytes. In this procedure, a small skin biopsy is taken from the retroauricular area and the keratinocytes are cultured. After 5 days, a membrane with the cells cultured is applied covering the denuded area. We find the autologous keratinocyte method a suitable option for the treatment of denuded areas in newborns, without causing any additional morbidity and in a very short period of time. PMID:26495236

DEVELOPMENT OF A SAMPLING PROCEDURE FOR LARGE NITROGEN- AND SULFUR-BEARING AEROSOLS

EPA Science Inventory

A single-stage impactor was modified to utilize a removable TFE impaction surface mounted on the end of an annular denuder. hen used with a polycarbonate filter coated with silicone oil, its cut point was 2.5 um and bounce was <1% for 8-um particles. ignificant bounce occurred wi...

Apatite Fission Track Constraints On The Denudational History Of The Bielsa And Millares Plutons, West-Central Pyrenees, Spain

NASA Astrophysics Data System (ADS)

Schwabe, E.; Fitzgerald, P. G.; Munoz, J. A.; Baldwin, S. L.

2006-12-01

The Pyreneean orogen extends for ~ 440 km from the Bay of Biscay to the Mediterranean Sea, forming a WNW-ESE topographic barrier between France and Spain. The mountain belt, formed by the Late Cretaceous-Early Miocene oblique collision and partial subduction of the Iberian Plate beneath the European Plate. Restored and balanced cross sections show a decrease in crustal shortening from ~165 km in the central Pyrenees to ~ 50 km in the Cantabrian margin, further to the west. The variation in shortening and crustal style is due to the decrease westward in convergence and differences in inherited geometry of pre- existing extensional faults. We propose the variation must also be reflected in the denudation record, with relative timing of the main denudational events younging to the west, as well as the magnitude and rates of denudation decreasing westward. In this study we analyze AFT data collected from vertical profiles on the southern flank of the mountains in the west-central Pyrenees. The results constrain the relative timing of structures between the central and west-central Pyrenees. AFTT data from the Bielsa and Millares massifs, located in the Bielsa and Millares thrust sheets on the southern flank of the axial zone, west-central Pyrenees yield AFT ages from 30 to 20 Ma. The data, including constraints from inverse thermal modeling, indicate denudation at rates ca. 300 m/my underway in the middle Oligocene, slowing in the Miocene. Denudation is likely related to erosion following thrusting during which the granites were transported within the south-vergent Bielsa and Millares thrust sheets. The Late Oligocene-Early Miocene AFT PAZ has since been exhumed to its present elevation. In form, results are similar to those from the central Pyrenees (Fitzgerald et al., 1999) but that Oligocene denudation in the west-central Pyrenees occurred later, was slower, and of reduced magnitude when compared to extremely rapid Oligocene denudation recorded ~50 km east in the central Pyrenees. There, as demonstrated in results from the Maladeta profile, denudation in the Early Oligocene is extremely rapid (km/my) followed by a slowing or cessation of exhumation. The Miocene PAZ preserved in both profiles suggests a similar post- orogenic history most likely related to filling and subsequent re-excavation of the Ebro Basin.

Late Quaternary denudation, Death and Panamint Valleys, eastern California

USGS Publications Warehouse

Jayko, A.S.

2005-01-01

Late Quaternary denudation rates are constrained from alluvial fans and tributary watersheds in central Death and Panamint Valleys. Preliminary results suggest that the denudation rate is in part a function of the mean watershed elevation. Rainfall increases semi-logarithmically with higher elevation to about 2500 m where it becomes limited by the regional average maximum moisture content of the air mass. The fan volumes show a power-law relation to the watershed areas. The fan volumes ranged from about 250,000 to 4000 km3 and the watershed areas range from about 60,000 to 2000 km2. The upper limit of the denudation rates estimated from small Death Valley fans restricted to the east side of the basin along the Black Mountain frontal scarp range between about 0.03 to 0.18 mm/yr. The maximum is made by assuming most of the clastic accumulation in these fans followed the last highstand of Lake Manly around 24,000 yr which is the least conservative condition. The upper limit of the denudation rates from the Panamint fans range from 0.04 to 0.20 mm/yr assuming the accumulation mainly postdates OIS-4 ???60,000 yr or OIS-2 ???20,000 yr based on the presence or absence of inset shorelines from the last glacial-pluvial maximum. The greater denudation rate associated with the higher mean watershed elevations can mainly be attributed to the greater rainfall at higher elevation. Denudation rates are about a third or less of the Neogene dip-slip rates reported from nearby active faults consistent with relief increasing during dryer periods. ?? 2005 Elsevier B.V. All rights reserved.

Validation of Ammonia Diffusive and Active Samplers in a Controlled Atmosphere Test Facility Using Traceable Primary Standard Gas Mixtures

NASA Astrophysics Data System (ADS)

Martin, N. A.; Ferracci, V.; Cassidy, N.; Hook, J.; Battersby, R. M.; Tang, Y. S.; Stevens, A. C. M.; Jones, M. R.; Braban, C. F.; Gates, L.; Hangartner, M.; Sacco, P.; Pagani, D.; Hoffnagle, J.

2016-12-01

Intensive farming, the increased use of fertilizers, and certain industrial processes are believed to be responsible for increases in the amount fraction of ammonia (NH3) found in Europe. NH3 contributes to eutrophication and acidification of land and freshwater, leading to a loss of biodiversity, undesirable changes to the ecosystem, and to secondary particulate matter (PM) formation. Measurements of ambient ammonia over a wide geographical area, are principally carried out with low-cost diffusive samplers or by active sampling with denuders, with each technique delivering time-integrated values over the monitoring period. The goal of this work was to measure the NH3 diffusive sampling rates of five different designs of commercial diffusive samplers (FSM Radiello radial sampler, Gradko diffusion tube, Gradko DIFRAM-400, Passam ammonia sampler, and CEH ALPHA sampler), together with validation tests with a denuder sampler (CEH DELTA denuder). The would deliver validated improvements in the accuracy of ambient measurements of NH3 in the field through the establishment of metrological traceability using new stable ammonia Primary Standard Gas Mixtures (PSMs), developed by gravimetry at NPL. All devices were simultaneously exposed in a controlled atmosphere test facility (CATFAC) containing traceable amount fractions of ammonia applicable to a range of ambient monitoring conditions, with well-defined conditions of temperature, relative humidity and wind speed. Online continuous monitoring of the test atmospheres was carried out with a calibrated cavity ring-down spectrometer modified to account for cross interference by water. Exposed samplers were analysed by individual manufacturers for ammonium using traceable wet chemical techniques. The measured diffusive sampling rates were then applied to field measurements carried out at the Whim Bog experimental station in Scotland, where there is a facility in place for controlled releases of NH3 and also a background site.

Comparison of gaseous oxidized Hg measured by KCl-coated denuders, and nylon and cation exchange membranes.

PubMed

Huang, Jiaoyan; Miller, Matthieu B; Weiss-Penzias, Peter; Gustin, Mae Sexauer

2013-07-02

The chemical compounds that make up gaseous oxidized mercury (GOM) in the atmosphere, and the reactions responsible for their formation, are not well understood. The limitations and uncertainties associated with the current method applied to measure these compounds, the KCl-coated denuder, are not known due to lack of calibration and testing. This study systematically compared the uptake of specific GOM compounds by KCl-coated denuders with that collected using nylon and cation exchange membranes in the laboratory and field. In addition, a new method for identifying different GOM compounds using thermal desorption is presented. Different GOM compounds (HgCl2, HgBr2, and HgO) were found to have different affinities for the denuder surface and the denuder underestimated each of these compounds. Membranes measured 1.3 to 3.7 times higher GOM than denuders in laboratory and field experiments. Cation exchange membranes had the highest collection efficiency. Thermodesorption profiles for the release of GOM compounds from the nylon membrane were different for HgO versus HgBr2 and HgCl2. Application of the new field method for collection and identification of GOM compounds demonstrated these vary as a function of location and time of year. Understanding the chemistry of GOM across space and time has important implications for those developing policy regarding this environmental contaminant.

Evaluating steady-state soil thickness by coupling uranium series and 10Be cosmogenic radionuclides

NASA Astrophysics Data System (ADS)

Vanacker, Veerle; Schoonejans, Jerome; Opfergelt, Sophie; Granet, Matthieu; Christl, Marcus; Chabaux, Francois

2017-04-01

Within the Critical Zone, the development of the regolith mantle is controlled by the downwards propagation of the weathering front into the bedrock and denudation at the surface of the regolith by mass movements, water and wind erosion. When the removal of surface material is approximately balanced by the soil production, the soil system is assumed to be in steady-state. The steady state soil thickness (or so-called SSST) can be considered as a dynamic equilibrium of the system, where the thickness of the soil mantle stays relatively constant over time. In this study, we present and compare analytical data from two independent isotopic techniques: in-situ produced cosmogenic nuclides and U-series disequilibria to constrain soil development under semi-arid climatic conditions. The Spanish Betic Cordillera (Southeast Spain) was selected for this study, as it offers us a unique opportunity to analyze soil thickness steady-state conditions for thin soils of semiarid environments. Three soil profiles were sampled across the Betic Ranges, at the ridge crest of zero-order catchments with distinct topographic relief, hillslope gradient and 10Be-derived denudation rate. The magnitude of soil production rates determined based on U-series isotopes (238U, 234U, 230Th and 226Ra) is in the same order of magnitude as the 10Be-derived denudation rates, suggesting steady state soil thickness in two out of three sampling sites. The results suggest that coupling U-series isotopes with in-situ produced radionuclides can provide new insights in the rates of soil development; and also illustrate the potential frontiers in applying U-series disequilibria to track soil production in rapidly eroding landscapes characterized by thin weathering depths.

Spatial and temporal variations in landscape evolution: historic and longer-term sediment flux through global catchments

USGS Publications Warehouse

Covault, Jacob A.; Craddock, William H.; Romans, Brian W.; Fildani, Andrea; Gosai, Mayur

2013-01-01

Sediment generation and transport through terrestrial catchments influence soil distribution, geochemical cycling of particulate and dissolved loads, and the character of the stratigraphic record of Earth history. To assess the spatiotemporal variation in landscape evolution, we compare global compilations of stream gauge–derived () and cosmogenic radionuclide (CRN)–derived (predominantly 10Be; ) denudation of catchments (mm/yr) and sediment load of rivers (Mt/yr). Stream gauges measure suspended sediment loads of rivers during several to tens of years, whereas CRNs provide catchment-integrated denudation rates at 102–105-yr time scales. Stream gauge–derived and CRN-derived sediment loads in close proximity to one another (<500 km) exhibit broad similarity ( stream gauge samples; CRN samples). Nearly two-thirds of CRN-derived sediment loads exceed historic loads measured at the same locations (). Excessive longer-term sediment loads likely are a result of longer-term recurrence of large-magnitude sediment-transport events. Nearly 80% of sediment loads measured at approximately the same locations exhibit stream gauge loads that are within an order of magnitude of CRN loads, likely as a result of the buffering capacity of large flood plains. Catchments in which space for deposition exceeds sediment supply have greater buffering capacity. Superior locations in which to evaluate anthropogenic influences on landscape evolution might be buffered catchments, in which temporary storage of sediment in flood plains can provide stream gauge–based sediment loads and denudation rates that are applicable over longer periods than the durations of gauge measurements. The buffering capacity of catchments also has implications for interpreting the stratigraphic record; delayed sediment transfer might complicate the stratigraphic record of external forcings and catchment modification.

Denudation rates determined from the accumulation of in situ-produced 10Be in the luquillo experimental forest, Puerto Rico

USGS Publications Warehouse

Brown, Erik Thorson; Stallard, Robert F.; Larsen, Matthew C.; Raisbeck, Grant M.; Yiou, Francoise

1995-01-01

We present a simple method for estimation of long-term mean denudation rates using in situ-produced cosmogenic 10Be in fluvial sediments. Procedures are discussed to account for the effects of soil bioturbation, mass wasting and attenuation of cosmic rays by biomass and by local topography. Our analyses of 10Be in quartz from bedrock outcrops, soils, mass-wasting sites and riverine sediment from the Icacos River basin in the Luquillo Experimental Forest, Puerto Rico, are used to characterize denudation for major landform elements in that basin. The 10Be concentration of a discharge-weighted average of size classes of river sediment corresponds to a long-term average denudation of ≈ 43 m Ma −1, consistent with mass balance results. 

Quantifying denudation of the West African passive-transform margin: implications for Cenozoic erosion budget of cratons and source-to-sink systems

NASA Astrophysics Data System (ADS)

Grimaud, Jean-Louis; Chardon, Dominique; Rouby, Delphine; Beauvais, Anicet

2014-05-01

We develop an approach based on the differential elevation of dated successive topographies of the onshore part of the West African margin to calibrate in-situ volumetric denudation over a 3.9 million km2 cratonic surface for the past 45 Ma. We obtain a regionally averaged volumetric erosion rate of 5 x 10-3 km3/km2/m.y. corresponding to a total average denudation of 300 m and a denudation rate of 6 m/m.y., which remained nearly constant over the three time spans (45- 24, 24-11 and 11-0 Ma) despite spatial variations related to epeirogenic movements. Denudation is converted into a minimum yield of 12 +/- 2 t/km2/yr with a minimum solute component of 4 +/- 2 t/km2/yr accounting for the porosity of the eroded regoliths. Our results would imply a minimum contribution of 1.6 +/- 0.4 Gt/yr of the non-orogenic landmass to the global continental yield since the last peak greenhouse. Reconstruction of two incision stages of West Africa landscape from the reconstructed topographies combined with paleogeographic data shows that the current river catchments of the sub region have acquired their current configuration by the end of the Oligocene at the latest (24 Ma ago). The fairly steady geometry of the West African drainage since then offers the opportunity to effectively link the inland geomorphic record to offshore sedimentation. Volumetric denudation analysis applied to West African sub-drainage areas attests to the role of drainage reorganization and epeirogenic mouvements (flexural growth of the marginal upwarp and amplification of the Hoggar intraplate swell) on the spatial and temporal distribution of continental denudation and yield. Onshore denudation and clastic sediments accumulation in the post-24 Ma Niger catchment - delta system are within the same order of magnitude. These results suggest that cratonic-type erosion fluxes estimated from the West African margin may be used to estimate the size of drainage basins from the fossil sedimentary record.

Semivolatile Particulate Organic Material Southern Africa during SAFARI 2000

NASA Technical Reports Server (NTRS)

Eatough, D. J.; Eatough, N. L.; Pang, Y.; Sizemore, S.; Kirchstetter, T. W.; Novakov, T.

2005-01-01

During August and September 2000, the University of Washington's Cloud and Aerosol Research Group (CARG) with its Convair-580 research aircraft participated in the Southern African Fire-Atmosphere Research Initiative (SAFARI) 2000 field study in southern Africa. Aboard this aircraft was a Particle Concentrator-Brigham Young University Organic Sampling System (PC-BOSS), which was used to determine semivolatile particulate material with a diffusion denuder sampler. Denuded quartz filters and sorbent beds in series were used to measure nonvolatile and semivolatile materials, respectively. Results obtained with the PC-BOSS are compared to those obtained with conventional quartz-quartz and Teflon-quartz filter pack samplers. Various 10-120 min integrated samples were collected during flights through the h e troposphere, in the atmospheric boundary layer, and in plumes from savanna fires. Significant fine particulate semivolatile organic compounds (SVOC) were found in all samples. The SVOC was not collected by conventional filter pack samplers and therefore would not have been determined in previous studies that used only filter pack samplers. The SVOC averaged 24% of the fine particulate mass in emissions from the fires and 36% of the fine particulate mass in boundary layer samples heavily impacted by aged emissions from savanna fires. Concentrations of fine particulate material in the atmospheric mixed layer heavily impacted by aged savanna frre emissions averaged 130 micrograms per cubic meter. This aerosol was 85% carbonaceous mated.

Controls of sediment transfers, sedimentary budgets and relief development in cold environments: Results from four catchment systems in Iceland, Swedish Lapland and Finnish Lapland

NASA Astrophysics Data System (ADS)

Beylich, A. A.

2012-04-01

By the combined, longer-term and quantitative recording of relevant denudative slope processes and stream work in four selected catchment systems in sub-arctic oceanic Eastern Iceland (Hrafndalur and Austdalur), arctic-oceanic Swedish Lapland (Latnjavagge) and sub-arctic oceanic Finnish Lapland (Kidisjoki), information on the absolute and relative importance of the different denudative processes is collected. Direct comparison of the four catchment geo-systems (the catchment sizes range from 7 km2 to 23 km2) allows conclusions on major controls of sediment transfers, sedimentary budgets and relief development in theses cold climate environments. To allow direct comparison of the different processes, all mass transfers are calculated as tonnes multiplied by meter per year, i.e. as the product of the annually transferred mass and the corresponding transport distance. Ranking the different processes according to their annual mass transfers shows that stream work dominates over slope denudation. For Hrafndalur (Eastern Iceland) the following order of denudative processes is found after nine years of process studies (2001 - 2010): (1) Fluvial suspended sediment plus bedload transport, (2) Fluvial solute transport, (3) Rock falls plus boulder falls, (4) Chemical slope denudation, (5) Mechanical fluvial slope denudation (slope wash), (6) Creep processes, (7) Avalanches, (8) Debris flows, (9) Translation slides, (10) Deflation. Compared to that, in Austdalur the following ranking is given after fourten years of process studies (1996 - 2010): (1) Fluvial suspended sediment plus bedload transport, (2) Fluvial solute transport, (3) Mechanical fluvial slope denudation (slope wash), (4) Chemical slope denudation, (5) Avalanches, (6) Rock falls plus boulder falls, (7) Creep processes, (8) Debris flows, (9) Deflation, (10) Translation slides. In the Latnjavagge catchment (Swedish Lapland) the ranking is (eleven-years period of studies, 1999 - 2010): (1) Fluvial solute transport, (2) Fluvial suspended sediment plus bedload transport, (3) Rock falls plus boulder falls, (4) Chemical slope denudation, (5) Mechanical fluvial slope denudation (slope wash), (6) Avalanches, (7) Creep processes and solifluction, (8) Slush flows, (9) Debris flows, (10) Translation slides, (11) Deflation. In Kidisjoki (Finnish Lapland) the order of processes, as determined after a nine-years period (2001 - 2010) of geomorphic process studies, is: (1) Fluvial solute transport, (2) Chemical slope denudation, (3) Fluvial suspended sediment plus bedload transport, (4) Mechanical fluvial slope denudation, (5) Creep processes, (6) Avalanches and slush flows, (7) Debris flows and slides, (8) Rock and boulder falls, (9) Deflation. As a result, in all four selected cold climate study areas the intensity of contemporary denudative processes and mass transfers is altogether rather low, which is in opposition to the earlier postulated oppinion of a generally high intensity of geomorphic processes in cold climate environments. A direct comparison of the annual mass transfers summarises that there are differences between process intensities and the relative importance of different denudative processes within the four study areas. The major controls of these detected differences are: (i) Climate: The higher annual precipitation along with the larger number of extreme rainfall events and the higher frequency of snowmelt and rainfall generated peak runoff events in Eastern Iceland as compared to Swedish Lapland and Finnish Lapland lead to higher mass transfers, (ii) Lithology: The low resistance of rhyolites in Hrafndalur causes especially high weathering rates and connected mass transfers in this catchment. Due to the lower resistance of the rhyolites as compared to the basalts found in Austdalur Postglacial modification of the glacially formed relief is clearly further advanced in Hrafndalur as compared to Austdalur, (iii) Relief: The greater steepness of the Icelandic catchments leads to higher mass transfers here as compared to Latnjavagge and Kidisjoki, (iv) Vegetation cover: The significant disturbance of the vegetation cover by human impacts in Easter Iceland causes higher mass transfers (slope wash) whereas restricted sediment availability is a main reason for lower mass transfers in Swedish Lapland and Finnish Lapland. The applied catchment-based approach seems to be effective for analysing sediment budgets and trends of Postglacial relief development in selected study areas with given environmental settings. Direct comparison of investigated catchments will improve possibilities to model relief development as well as possible effects of projected climate change in cold climate environments.

Testing The Magmatic Underplating Hypothesis: An Example From The Uk and Ireland

NASA Astrophysics Data System (ADS)

Al-Kindi, S.; White, N.; Sinha, M.; England, R.

Magmatic underplating associated with mantle plume activity is an important mech- anism for driving regional surface uplift and denudation of large portion of the continents. Here we present quantitative and predictive models linking the surface- measured uplift and denudation with deep crustal structure across the British Isles. The crustal model was derived from re-interpreting the 1982 wide-angle Caledonian Suture Seismic Project and it's Irish extension (CSSP&ICSSP) data sets. A joint CSSP/ICSSP velocity model was obtained for the first time by inverting for six main travel-time phases comprising more than 3000 picks having picking uncertainty ranges of 50-100 ms and average of 82 ms with best picks for first breaks at close offsets. Two indepen- dent tomographic codes namely RAYINVR (Zelt and Smith, 1992) and Jive3D (Ho- bro, 2000) were used to model the picked travel-times adopting 'interpreter-guided' and 'pure tomographic' approaches, respectively. The codes represent natural end- member approaches to travel-time tomography where the former seeks an irregular grid, minimum-parameter velocity model, whereas the later seeks minimum-structure velocity model. The final outcome of the two methods are remarkably similar which has greatly boosted confidence in the interpretation. Complementary resolution and uncertainty tests were preformed. The most striking feature of the outcome of the inversion processes is the emergence of a discrete high-velocity (7.0-7.5 km/s) intermediate layer above the Moho. The top interface of this layer is sampled by lower crustal reflections, whereas the layer velocity is sampled by refracted rays. The base of the layer is bounded by the Moho interface roughly at 33 km, constrained by upper mantle diving rays. Some Moho reflections were observed on some record sections, but the majority are believed to be masked by the early arriving, highly-reflective coda generated by resonance of seismic waves within the intermediate layer. The layer has maximum thickness of 8 + 1.6 km roughly half-way across the East Irish Sea and thins out towards the edges. The minimum width of this layer is well constrained by the strong lower crustal reflections to be approximately 550 km. The maximum width, could extend outside the ray coverage of this experiment with maximum layer thickness of 2 km at the edge of the model. This is roughly of the thickness of the smallest resolvable structure 1 at a depth of 30 km using a 5 Hz signal. Filtered gravity data was used to model a density model derived by converting the final preferred velocity model using an appropriate P-wave velocity-to-density conversion. The profile is characterised by a high positive gravity anomaly of about 30 mGal over the East Irish Sea. An excess of denser material in the lower crust (+0.20 Mgm-3) was essential to account for this gravity high, which is consistent with the wide-angle velocity model. Synthetic denudation values were calculated along the 2D crustal model assuming Airly isostasy for different elastic thickness, and were compared to real estimates pro- vided by Rowely, 1998. The two data sets show good correlation within the uncertain- ties of the estimates, which has encouraged futher analysis. An attempt at extending the two-dimensional results into the third dimension was carried out based on a sta- tistical correlation of 800 pairs of modelled underplating thickness values and 150 km high-pass gravity samples along the 2D line. The analysis has shown a high posi- tive correlation with R2=0.72 with a significant linear regression at the 95% confident level. This relationship was then computed to predict underplate thickness from the filtered gravity map and then compared with the available denudation maps. This anal- ysis has highlighted specific areas where underplating is postulated to derive surface uplift. 2

Chemical weathering in response to tectonic uplift and denudation rate in a semi-arid environment, southeast Spain

NASA Astrophysics Data System (ADS)

Ameijeiras-Mariño, Yolanda; Opfergelt, Sophie; Schoonejans, Jérôme; Vanacker, Veerle; Sonnet, Philippe; Delmelle, Pierre

2014-05-01

Soil thickness reflects the balance between soil production and denudation by chemical weathering and physical erosion. At topographic steady state, the soil weathering intensity is expected to be higher at low denudation rate (transport-limited) than at high denudation rate (weathering-limited). We tested this hypothesis for the first time in a semi-arid environment where chemical weathering processes are generally slow. The study site is the Internal Zone of the Betic Cordillera in Southeast Spain, Almeria province. The lithology is mainly mica-schist and quartzite with local presence of phyllite. Three catchments (EST, FIL, CAB) were selected upstream local faults along a gradient of increasing uplift rates (10-170 mm/kyr) and increasing denudation rates (20-250 mm/kyr), following the sequence EST

Denudation rates derived from spatially-averaged cosmogenic nuclide analysis in Nelson catchments, South Island, New Zealand

NASA Astrophysics Data System (ADS)

Burdis, A.; Norton, K. P.; Ditchburn, B.; Zondervan, A.

2013-12-01

New Zealand's tectonically and climatically dynamic environment generates erosion rates that outstrip global averages by up to ten times in some locations. In order to assess recent changes in erosion rate, and also to predict future erosion dynamics, it is important to quantify long-term, background erosion. Current research on erosion in New Zealand predominantly covers short-term (100 yrs) erosion dynamics and Myr dynamics from thermochronological proxy data. Without medium-term denudation data for New Zealand, it is uncertain which variables (climate, anthropogenic disturbance of the landscape, tectonic uplift, lithological, or geomorphic characteristics) exert the dominant control on denudation in New Zealand. Spatially-averaged cosmogenic nuclide analysis can effectively offer this information by providing averaged rates of denudation on millennial timescales without the biases and limitations of short-term erosion methods. Basin-averaged denudation rates were obtained in the Nelson region, New Zealand, from analysis of concentrations of meteoric 10Be in clay and in-situ produced 10Be in quartz. The measured denudation rates integrate over ~8000 yrs (meteoric) and ~3000 yrs (in-situ). Not only do the 10Be records produce erosion rates that are remarkably consistent with each other, but they are also independent of topographic metrics. Denudation rates range from ~116 - 306 t km-2 yr-1, with the exception of one basin which is eroding at 789 t km-2 yr-1(derived from meteoric 10Be) and 644 t km-2 yr-1(derived from in-situ 10Be). The homogeneity of rates and absence of a significant correlation with geomorphic or lithological characteristics suggest another factor is exerting the dominant control on landscape denudation in the Nelson region. Storm variability is a likely driver of erosion in this setting. The background rates are higher than current short term rates (~50 - 200 t km-2 yr-1) due to the significant erosion caused by high magnitude, low frequency events. This is highlighted by sediment yields reaching ~2535 t km-2 yr-1 following storm events in the Nelson region (Basher et al., 2011). At least on the northern South Island of New Zealand, extreme climatic events appear to be the main driver of elevated denudation rates. Basher, L., Hicks, D., Clapp, B., & Hewitt, T. (2011). Sediment Yield Response to Large Storm Events and Forest Harvesting, Motueka River, New Zealand. New Zealand Journal ofMarine and Freshwater Research, Vol. 45, No. 3 , 333-356.

Uncertainties of Gaseous Oxidized Mercury Measurements Using KCl-Coated Denuders, Cation-Exchange Membranes, and Nylon Membranes: Humidity Influences.

PubMed

Huang, Jiaoyan; Gustin, Mae Sexauer

2015-05-19

Quantifying the concentration of gaseous oxidized mercury (GOM) and identifying the chemical compounds in the atmosphere are important for developing accurate local, regional, and global biogeochemical cycles. The major hypothesis driving this work was that relative humidity affects collection of GOM on KCl-coated denuders and nylon membranes, both currently being applied to measure GOM. Using a laboratory manifold system and ambient air, GOM capture efficiency on 3 different collection surfaces, including KCl-coated denuders, nylon membranes, and cation-exchange membranes, was investigated at relative humidity ranging from 25 to 75%. Recovery of permeated HgBr2 on KCl-coated denuders declined by 4-60% during spikes of relative humidity (25 to 75%). When spikes were turned off GOM recoveries returned to 60 ± 19% of permeated levels. In some cases, KCl-coated denuders were gradually passivated over time after additional humidity was applied. In this study, GOM recovery on nylon membranes decreased with high humidity and ozone concentrations. However, additional humidity enhanced GOM recovery on cation-exchange membranes. In addition, reduction and oxidation of elemental mercury during experiments was observed. The findings in this study can help to explain field observations in previous studies.

Measuring ammonia concentrations and emissions from agricultural land and liquid surfaces: a review.

PubMed

Shah, Sanjay B; Westerman, Philip W; Arogo, Jactone

2006-07-01

Aerial ammonia concentrations (Cg) are measured using acid scrubbers, filter packs, denuders, or optical methods. Using Cg and wind speed or airflow rate, ammonia emission rate or flux can be directly estimated using enclosures or micrometeorological methods. Using nitrogen (N) recovery is not recommended, mainly because the different gaseous N components cannot be separated. Although low cost and replicable, chambers modify environmental conditions and are suitable only for comparing treatments. Wind tunnels do not modify environmental conditions as much as chambers, but they may not be appropriate for determining ammonia fluxes; however, they can be used to compare emissions and test models. Larger wind tunnels that also simulate natural wind profiles may be more useful for comparing treatments than micrometeorological methods because the latter require larger plots and are, thus, difficult to replicate. For determining absolute ammonia flux, the micrometeorological methods are the most suitable because they are nonintrusive. For use with micrometeorological methods, both the passive denuders and optical methods give comparable accuracies, although the latter give real-time Cg but at a higher cost. The passive denuder is wind weighted and also costs less than forced-air Cg measurement methods, but it requires calibration. When ammonia contamination during sample preparation and handling is a concern and separating the gas-phase ammonia and aerosol ammonium is not required, the scrubber is preferred over the passive denuder. The photothermal interferometer, because of its low detection limit and robustness, may hold potential for use in agriculture, but it requires evaluation. With its simpler theoretical basis and fewer restrictions, the integrated horizontal flux (IHF) method is preferable over other micrometeorological methods, particularly for lagoons, where berms and land-lagoon boundaries modify wind flow and flux gradients. With uniform wind flow, the ZINST method requiring measurement at one predetermined height may perform comparably to the IHF method but at a lower cost.

Atmospheric Oxidation of 1,3-Butadiene: Characterization of gas and aerosol reaction products and implication for PM2.5

EPA Science Inventory

Secondary organic aerosol (SOA) was generated by irradiating 1,3-butadiene (13BD) in the presence of H2O2 or NOx. Experiments were conducted in a smog chamber operated in either flow or batch mode. A filter/denuder sampling system was used for simultaneously collecting gas and pa...

Transient river response, captured by channel steepness and its concavity

NASA Astrophysics Data System (ADS)

Vanacker, Veerle; von Blanckenburg, Friedhelm; Govers, Gerard; Molina, Armando; Campforts, Benjamin; Kubik, Peter W.

2015-01-01

Mountain rivers draining tropical regions are known to be great conveyor belts carrying efficiently more than half of the global sediment flux to the oceans. Many tropical mountain areas are located in tectonically active belts where the hillslope and stream channel morphology are rapidly evolving in response to changes in base level. Here, we report basin-wide denudation rates for an east-west transect through the tropical Andes. Hillslope and channel morphology vary systematically from east to west, reflecting the transition from high relief, strongly dissected topography in the escarpment zones into relatively low relief topography in the inter-Andean valley. The spatial pattern of differential denudation rates reflects the transient adjustment of the landscape to rapid river incision following tectonic uplift and river diversion. In the inter-Andean valley, upstream of the wave of incision, slopes and river channels display a relatively smooth, concave-up morphology and denudation rates (time scale of 104-105 a) are consistently low (3 to 200 mm/ka). In contrast, slopes and river channels of rejuvenated basins draining the eastern cordillera are steep to very steep; and the studied drainage basins show a wide range of denudation rate values (60 to 400 mm/ka) that increase systematically with increasing basin mean slope gradient, channel steepness, and channel convexity. Drainage basins that are characterised by strong convexities in their river longitudinal profiles systematically have higher denudation rates. As such, this is one of the first studies that provides field-based evidence of a correlation between channel concavity and basin mean denudation rates, consistent with process-based fluvial incision models.

Recent topographic evolution and erosion of the deglaciated Washington Cascades inferred from a stochastic landscape evolution model

NASA Astrophysics Data System (ADS)

Moon, Seulgi; Shelef, Eitan; Hilley, George E.

2015-05-01

In this study, we model postglacial surface processes and examine the evolution of the topography and denudation rates within the deglaciated Washington Cascades to understand the controls on and time scales of landscape response to changes in the surface process regime after deglaciation. The postglacial adjustment of this landscape is modeled using a geomorphic-transport-law-based numerical model that includes processes of river incision, hillslope diffusion, and stochastic landslides. The surface lowering due to landslides is parameterized using a physically based slope stability model coupled to a stochastic model of the generation of landslides. The model parameters of river incision and stochastic landslides are calibrated based on the rates and distribution of thousand-year-time scale denudation rates measured from cosmogenic 10Be isotopes. The probability distributions of those model parameters calculated based on a Bayesian inversion scheme show comparable ranges from previous studies in similar rock types and climatic conditions. The magnitude of landslide denudation rates is determined by failure density (similar to landslide frequency), whereas precipitation and slopes affect the spatial variation in landslide denudation rates. Simulation results show that postglacial denudation rates decay over time and take longer than 100 kyr to reach time-invariant rates. Over time, the landslides in the model consume the steep slopes characteristic of deglaciated landscapes. This response time scale is on the order of or longer than glacial/interglacial cycles, suggesting that frequent climatic perturbations during the Quaternary may produce a significant and prolonged impact on denudation and topography.

Denudation of metal powder layers in laser powder bed fusion processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matthews, Manyalibo J.; Guss, Gabe; Khairallah, Saad A.

Understanding laser interaction with metal powder beds is critical in predicting optimum processing regimes in laser powder bed fusion additive manufacturing of metals. In this work, we study the denudation of metal powders that is observed near the laser scan path as a function of laser parameters and ambient gas pressure. We show that the observed depletion of metal powder particles in the zone immediately surrounding the solidified track is due to a competition between outward metal vapor flux directed away from the laser spot and entrainment of powder particles in a shear flow of gas driven by a metalmore » vapor jet at the melt track. Between atmospheric pressure and ~10 Torr of Ar gas, the denuded zone width increases with decreasing ambient gas pressure and is dominated by entrainment from inward gas flow. The denuded zone then decreases from 10 to 2.2 Torr reaching a minimum before increasing again from 2.2 to 0.5 Torr where metal vapor flux and expansion from the melt pool dominates. In addition, the dynamics of the denudation process were captured using high-speed imaging, revealing that the particle movement is a complex interplay among melt pool geometry, metal vapor flow, and ambient gas pressure. The experimental results are rationalized through finite element simulations of the melt track formation and resulting vapor flow patterns. The results presented here represent new insights to denudation and melt track formation that can be important for the prediction and minimization of void defects and surface roughness in additively manufactured metal components.« less

Denudation of metal powder layers in laser powder bed fusion processes

DOE PAGES

Matthews, Manyalibo J.; Guss, Gabe; Khairallah, Saad A.; ...

2016-05-20

Understanding laser interaction with metal powder beds is critical in predicting optimum processing regimes in laser powder bed fusion additive manufacturing of metals. In this work, we study the denudation of metal powders that is observed near the laser scan path as a function of laser parameters and ambient gas pressure. We show that the observed depletion of metal powder particles in the zone immediately surrounding the solidified track is due to a competition between outward metal vapor flux directed away from the laser spot and entrainment of powder particles in a shear flow of gas driven by a metalmore » vapor jet at the melt track. Between atmospheric pressure and ~10 Torr of Ar gas, the denuded zone width increases with decreasing ambient gas pressure and is dominated by entrainment from inward gas flow. The denuded zone then decreases from 10 to 2.2 Torr reaching a minimum before increasing again from 2.2 to 0.5 Torr where metal vapor flux and expansion from the melt pool dominates. In addition, the dynamics of the denudation process were captured using high-speed imaging, revealing that the particle movement is a complex interplay among melt pool geometry, metal vapor flow, and ambient gas pressure. The experimental results are rationalized through finite element simulations of the melt track formation and resulting vapor flow patterns. The results presented here represent new insights to denudation and melt track formation that can be important for the prediction and minimization of void defects and surface roughness in additively manufactured metal components.« less

An analytical method for trifluoroacetic Acid in water and air samples using headspace gas chromatographic determination of the methyl ester.

PubMed

Zehavi, D; Seiber, J N

1996-10-01

An analytical method has been developed for the determination of trace levels of trifluoroacetic acid (TFA), an atmospheric breakdown product of several of the hydrofluorocarbon (HFC) and hydrochlorofluorocarbon (HCFC) replacements for the chlorofluorocarbon (CFC) refrigerants, in water and air. TFA is derivatized to the volatile methyl trifluoroacetate (MTFA) and determined by automated headspace gas chromatography (HSGC) with electron-capture detection or manual HSGC using GC/MS in the selected ion monitoring (SIM) mode. The method is based on the reaction of an aqueous sample containing TFA with dimethyl sulfate (DMS) in concentrated sulfuric acid in a sealed headspace vial under conditions favoring distribution of MTFA to the vapor phase. Water samples are prepared by evaporative concentration, during which TFA is retained as the anion, followed by extraction with diethyl ether of the acidified sample and then back-extraction of TFA (as the anion) in aqueous bicarbonate solution. The extraction step is required for samples with a relatively high background of other salts and organic materials. Air samples are collected in sodium bicarbonate-glycerin-coated glass denuder tubes and prepared by rinsing the denuder contents with water to form an aqueous sample for derivatization and analysis. Recoveries of TFA from spiked water, with and without evaporative concentration, and from spiked air were quantitative, with estimated detection limits of 10 ng/mL (unconcentrated) and 25 pg/mL (concentrated 250 mL:1 mL) for water and 1 ng/m(3) (72 h at 5 L/min) for air. Several environmental air, fogwater, rainwater, and surface water samples were successfully analyzed; many showed the presence of TFA.

Removal of atmospheric oxidants with annular denuders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, E.L. II; Grosjean, D.

1990-06-01

Annular denuders have been tested for their ability to remove atmospheric photochemical oxidants including ozone (150-170 ppb), nitrogen dioxide (40-200 ppb), nitric acid (35 ppb), and peroxyacetyl nitrate (PAN, 6-25 ppb). Formaldehyde (80-140 ppb) was also tested as a copollutant. Tests were carried out at low rates of 1,2, and 20 L/min, with oxidants tested singly or as part of photochemical mixtures in purified air. Efficient collection was obtained with annular denuders coated with potassium iodide (O{sub 3}), phenoxamine (O{sub 3}), sodium carbonate (HNO{sub 3}), potassium hydroxide (PAN), and 2,4-dinitrophenylhydrazine (HCHO).

Role of vegetation in modulating denudation and topography across the Himalaya

NASA Astrophysics Data System (ADS)

Olen, Stephanie; Bookhagen, Bodo; Strecker, Manfred

2015-04-01

Studies of Himalayan denudation, to date, have primarily focused on the effects of lithology, tectonic activity, and climate in shaping landscape and controlling denudation rates. Climate can impact denudation not only through increased precipitation, runoff, or glaciation, but also via its role in controlling vegetation cover. Since the classical study of Langbein and Schumm [1958] emphasizing the role of vegetation cover in determining erosional efficiency, theoretical and plot-scale studies have highlighted the role of vegetation on surface processes [Collins et al., 2004; Istanbulluoglu and Bras, 2005; Collins and Bras, 2010; Carretier et al., 2013; Jeffery et al., 2014]. Vegetation cover and density vary considerably in the Himalaya, both across and along strike. Across strike, vegetation transitions from dense forest and agriculturally-used plots in the Lesser Himalaya to sparse alpine and arid, virtually non-vegetated regions at high elevation and in the rain shadow north of the Higher Himalaya peaks. Along-strike vegetation densities also differ significantly and show a pronounced E-W gradient. To quantify the along-strike vegetation gradient, we use 14 years of MODIS 13C1 enhanced vegetation index (EVI) data to calculate mean annual, summer (MJJASO), and winter (NDJFMA) for the entire Himalaya. Additionally, we calculate a differential EVI that compares summer versus winter vegetation density (MJJASO/NDJFMA). A decrease in vegetation density is observed from east to west, with the greatest difference in winter vegetation cover (225% higher in the eastern than western Himalaya). In contrast, differential EVI is higher in the western Himalaya, increasing 170% from east to west. To evaluate the effect of vegetation on denudation and landscape evolution, we combine the 14-year EVI data, topographic analysis, and a compilation of >100 published and unpublished 10-Be terrestrial cosmogenic nuclide (TCN) catchment-mean denudation rates from across the Himalaya [Godard et al., 2014; Portenga et al., 2014; Scherler et al., 2014; Olen et al., submitted]. We calculate the relationship between various topographic metrics (e.g. mean basin slope, normalized channel steepness [ksn]) and the TCN catchment-mean denudation of non-glaciated fluvial watersheds from previously published and submitted studies. The variation in vegetation density between study sites correlates with the relationship between topography and denudation in each region. In sparsely vegetated areas, denudation increases in a rapid, non-linear fashion as topographic metrics such as the normalized channel steepness (ksn) or mean basin hillslope increase. Where vegetation cover is denser, the relationship between denudation and topography becomes increasingly linear, such that lower denudation rates are maintained as hillslopes and channels steepen. Additionally, more sparsely vegetated regions appear to reach a maximum steepness lower than that observed in densely vegetated regions. We therefore observe a negative correlation between increasing annual, summer, and winter EVI and the power-law exponent p of the relationship denudation ≈ (topographic metric)p; and a positive correlation between p and differential EVI. In contrast to recent studies arguing that Himalayan denudation is primarily forced by tectonics, our study emphasizes how vegetation density, as a climatic agent, modulates erosional style and landscape development along strike across the Himalaya. Carretier, S., et al. (2013), Slope and climate variability control of erosion in the Andes of central Chile, Geology, 41(2), 195-198. Collins, D. B. G., and R. L. Bras (2010), Climatic and ecological controls of equilibrium drainage density, relief, and channel concavity in dry lands, Water Resources Research, 46(4), W04508. Collins, D. B. G., R. L. Bras, and G. E. Tucker (2004), Modeling the effects of vegetation-erosion coupling on landscape evolution, Journal of Geophysical Research: Earth Surface, 109(F3), F03004. Godard, V., D. L. Bourlés, F. Spinabella, D. W. Burbank, B. Bookhagen, G. B. Fisher, A. Moulin, and L. Léanni (2014), Dominance of tectonics over climate in Himalayan denudation, Geology. Istanbulluoglu, E., and R. L. Bras (2005), Vegetation-modulated landscape evolution: Effects of vegetation on landscape processes, drainage density, and topography, Journal of Geophysical Research: Earth Surface, 110(F2), F02012. Jeffery, M. L., B. J. Yanites, C. J. Poulsen, and T. A. Ehlers (2014), Vegetation-precipitation controls on Central Andean topography, Journal of Geophysical Research: Earth Surface, 2013JF002919. Langbein, W., and S. Schumm (1958), Yield of sediment in relation to mean annual precipitation, American Geophysical Union Transactions, 39, 1076-1084. Portenga, E. W., P. R. Bierman, C. Duncan, L. B. Corbett, N. M. Kehrwald, and D. H. Rood (2014), Erosion rates of the Bhutanese Himalaya determined using in situ-produced 10Be, Geomorphology(0). Scherler, D., B. Bookhagen, and M. R. Strecker (2014), Tectonic control on 10Be-derived erosion rates in the Garhwal Himalaya, India, Journal of Geophysical Research: Earth Surface, 2013JF002955.

Presence of encircling granulosa cells protects against oxidative stress-induced apoptosis in rat eggs cultured in vitro.

PubMed

Tiwari, Meenakshi; Tripathi, Anima; Chaube, Shail K

2017-01-01

Increased oxidative stress (OS) due to in vitro culture conditions can affect the quality of denuded eggs during various assisted reproductive technologies (ARTs). Presence of intact granulosa cells may protect eggs from OS damage under in vitro culture conditions. The present study was aimed to investigate whether encircling granulosa cells could protect against hydrogen peroxide (H 2 O 2 )-induced egg apoptosis in ovulated cumulus oocyte complexes (COCs) cultured in vitro. The OS was induced by exposing COCs as well as denuded eggs with various concentrations of H 2 O 2 for 3 h in vitro. The morphological changes, total reactive oxygen species (ROS) as well as catalase expression, Bax/Bcl-2, cytochrome c levels and DNA fragmentation were analysed in COCs as well as denuded eggs. Our results suggest that H 2 O 2 treatment induced morphological apoptotic features in a concentration-dependent manner in denuded eggs cultured in vitro. The 20 µM of H 2 O 2 treatment induced OS by elevating total ROS level, reduced catalase and Bcl-2 expression levels with overexpression of Bax and cytochrome c and induced DNA fragmentation in denuded eggs cultured in vitro. The presence of encircling granulosa cells protected H 2 O 2 -induced morphological apoptotic features by preventing the increase of Bax, cytochrome c expression levels and DNA fragmentation in associated egg. However, 20 µM of H 2 O 2 was sufficient to induce peripheral granulosa cell apoptosis in COCs and degeneration in few denuded eggs cultured in vitro. Taken together our data suggest that the presence of encircling granulosa cells could be beneficial to protect ovulated eggs from OS damage under in vitro culture conditions during various ART programs.

One million years of glaciation and denudation history in west Greenland

PubMed Central

Strunk, Astrid; Knudsen, Mads Faurschou; Egholm, David L.; Jansen, John D.; Levy, Laura B.; Jacobsen, Bo H.; Larsen, Nicolaj K.

2017-01-01

The influence of major Quaternary climatic changes on growth and decay of the Greenland Ice Sheet, and associated erosional impact on the landscapes, is virtually unknown beyond the last deglaciation. Here we quantify exposure and denudation histories in west Greenland by applying a novel Markov-Chain Monte Carlo modelling approach to all available paired cosmogenic 10Be-26Al bedrock data from Greenland. We find that long-term denudation rates in west Greenland range from >50 m Myr−1 in low-lying areas to ∼2 m Myr−1 at high elevations, hereby quantifying systematic variations in denudation rate among different glacial landforms caused by variations in ice thickness across the landscape. We furthermore show that the present day ice-free areas only were ice covered ca. 45% of the past 1 million years, and even less at high-elevation sites, implying that the Greenland Ice Sheet for much of the time was of similar size or even smaller than today. PMID:28098141

A 10Be-based sediment budget of the Upper Rhône basin, Central Swiss Alps

NASA Astrophysics Data System (ADS)

Stutenbecker, Laura; Delunel, Romain; Schlunegger, Fritz; Akçar, Naki; Christl, Marcus

2017-04-01

The Upper Rhône catchment located in southwestern Switzerland is one of the largest Alpine intramontane basins and, due to high topographic gradients and intense glacial conditioning, an important sediment factory in the Alps. Sediment is being produced in around 50 tributary basins, transported along the 150 km long course of the Rhône River, and deposited in the river delta and associated subaquatic canyons within Lake Geneva, its primary sedimentary sink. In order to quantify the modern sediment fluxes in this Alpine basin we infer catchment-wide denudation rates from concentrations of the cosmogenic nuclide 10Be in quartz extracted from modern fluvial sediment of the major tributary basins. Additionally, 10Be-based denudation rates are calculated for 14 locations along the main Rhône River to track downstream changes. Results from the tributary basins show a large scatter of 10Be concentrations and their respective inferred denudation rates, ranging from 9.72 x 104 atoms/g and 0.17 mm/a to 0.13 x 104 atoms/g and 2.64 mm/a. The Rhône basin does show a rather large spatial variability of parameters that are known to possibly influence denudation rates, for example recent rock uplift rates, lithology, precipitation and temperature, as well as geomorphological parameters such as relief, mean elevation and slope values. However, there is no significant correlation between those parameters and the calculated denudation rates. Instead, the denudation rates are found to be positively correlated with the recent glacial cover in the catchments. This suggests that in glaciated basins glaciogenic material with very low 10Be concentrations is the dominating source of sediment, and inferred denudation rates must be interpreted with great care, as they may overestimate the actual rates. Downstream the main Rhône River the 10Be-concentrations are rather stable and do not record significant inputs of the glaciogenic material supplied by the glaciated basins. Possible explanations we would like to discuss here include differences in sediment connectivity and temporary sediment storage.

Evidence of a temperature transition for denuded zone formation in nanocrystalline Fe under He irradiation

DOE PAGES

El-Atwani, Osman; Nathaniel II, James E.; Leff, Asher C.; ...

2016-10-18

Nanocrystalline materials are radiation-tolerant materials’ candidates due to their high defect sink density. Here, nanocrystalline iron films were irradiated with 10 keV helium ions in situ in a transmission electron microscope at elevated temperatures. Grain-size-dependent bubble density changes and denuded zone occurrence were observed at 700 K, but not at 573 K. This transition, attributed to increased helium–vacancy migration at elevated temperatures, suggests that nanocrystalline microstructures are more resistant to swelling at 700 K due to decreased bubble density. Finally, denuded zone formation had no correlation with grain size and misorientation angle under the conditions studied.

A continuous-flow denuder for the measurement of ambient concentrations and surface-exchange fluxes of ammonia

NASA Astrophysics Data System (ADS)

Wyers, G. P.; Otjes, R. P.; Slanina, J.

A new diffusion denuder is described for the continuous measurement of atmospheric ammonia. Ammonia is collected in an absorption solution in a rotating denuder, separated from interfering compounds by diffusion through a semi-permeable membrane and detected by conductometry. The method is free from interferences by other atmospheric gases, with the exception of volatile amines. The detection limit is 6 ng m -3 for a 30-min integration time. This compact instrument is fully automated and suited for routine deployment in field studies. The precision is sufficiently high for micrometeorological studies of air-surface exchange of ammonia.

Denudational slope processes and slope response to global climate changes and other disturbances: insights from the Nepal Himalayas.

NASA Astrophysics Data System (ADS)

Fort, Monique

2016-04-01

Hillslope geomorphology results from a large range of denudational processes mainly controlled by relief, structure, lithology, climate, land-cover and land use. In most areas of the world, the "critical zone" concept is a good integrator of denudation that operates on a long-term scale. However, in large and high mountain areas, short-time scale factors often play a significant role in the denudational pattern, accelerating and/or delaying the transfer of denudation products and fluxes, and creating specific, spatially limited disturbances. We focus on the Nepal Himalayas, where the wide altitudinal range of bio-climatic zones and the intense geodynamic activity create a complex mosaic of landforms, as expressed by the present geomorphology of mountain slopes. On the basis of examples selected in the different Himalayan mountain belts (Siwaliks hills, middle mountains, High Himalaya), we illustrate different types of slopes and disturbances induced by active tectonics, climate extremes, and climate warming trends. Special attention is paid to recent events, such as landslide damming, triggered by either intense rainfalls (Kali Gandaki and Sun Kosi valleys) or the last April-May 2015 Gorkha seismic sequence (southern Khumbu). Lastly, references to older, larger events show that despite the highly dynamic environment, landforms caused by large magnitude disturbances may persist in the landscape in the long term.

Kinetically limited weathering at low denudation rates in semiarid climatic conditions

NASA Astrophysics Data System (ADS)

Schoonejans, Jérôme; Vanacker, Veerle; Opfergelt, Sophie; Ameijeiras-Mariño, Yolanda; Christl, Marcus

2016-02-01

Biogeochemical cycling within the Critical Zone depends on the interactions between minerals and fluids controlling chemical weathering and physical erosion rates. In this study, we explore the role of water availability in controlling soil chemical weathering in semiarid climatic conditions. Weathering rates and intensities were evaluated for nine soil profiles located on convex ridge crests of three mountain ranges in the Spanish Betic Cordillera. We combine a geochemical mass balance with 10Be cosmogenic nuclides to constrain chemical weathering intensities and long-term denudation rates. As such, this study presents new data on chemical weathering and 10Be-derived denudation for understudied semiarid climate systems. In the Betic Cordillera, chemical weathering intensities are relatively low (~5 to 30% of the total denudation of the soil) and negatively correlated with the magnitude of the water deficit in soils. Chemical mass losses are inversely related to denudation rates (14-109 mm/kyr) and positively to soil thickness (14-58 cm); these results are consistent with kinetic limitation of chemical weathering rates. A worldwide compilation of chemical weathering data suggests that soil water balance may regulate the coupling between chemical weathering and physical erosion by modulating soil solute fluxes. Therefore, future landscape evolution models that seek to link chemical weathering and physical erosion should include soil water flux as an essential driver of weathering.

DETERMINATION OF THE STRONG ACIDITY OF ATMOSPHERIC FINE PARTICLES (<2.5 UM) USING ANNULAR DENUDER TECHNOLOGY

EPA Science Inventory

This report is a standardized methodology description for the determination of strong acidity of fine particles (less than 2.5 microns) in ambient air using annular denuder technology. his methodology description includes two parts: art A - Standard Method and Part B - Enhanced M...

Weathering as the limiting factor of denudation in the Western escarpment of the Andes

NASA Astrophysics Data System (ADS)

Abbühl, L. M.; Schlunegger, F.; Kracht, O.; Ramseyer, K.; Rieke-Zapp, D.; Aldahan, A.; von Blanckenburg, F.

2009-04-01

A crucial issue in process geomorphology is the search for the scale and the extent to which precipitation, and climate in general, influences the nature and the rates of sediment transfer (weathering, erosion, sediment transport and deposition). We present an analysis of the possible interplay between precipitation, weathering and denudation rates for the western Andean slope between the Cordillera and the Pacific coast. It is based on morphometric studies and quantitative 10Be denudation rate estimates of three transverse river systems (Piura at 5°S, Pisco at 13°S, and Lluta at 18°S) draining the Western escarpment of the Peruvian and North Chilean Andes. The systems originate at elevations >3000 m above sea level, cover an area between 3000 and 10'000 km2 and discharge into the Pacific Ocean. The precipitation rate pattern implies a hyperarid climate at the coast, and semi-arid to semi-humid conditions in the Cordillera where the streams rise. There, climatic conditions are generally controlled by the easterlies that deliver moisture from the Atlantic Ocean via the low level Andean jet. The precipitation rate pattern of the Cordillera shows a North-South decreasing trend, from ca. 1000 mm/yr in Northern Peru to 150 mm/yr in Northern Chile. In these higher regions of the drainage basins, hillslopes are convex with nearly constant curvatures and are mantled by a >1 m thick regolith cover. In addition, hillslope erosion is limited to the regolith-bedrock interface. We interpret these geomorphic features to indicate weathering-controlled sediment discharge. In the lower river segments, beyond tectonic knickzones, regular precipitation is almost absent. For the case of the Piura river in Northern Peru, precipitation in this segment occurs in relation to highly episodic El Niño events related to the westerlies. This results in a supply-limited sediment discharge, leading to predominance of channelized processes on the hillslopes, a spare regolith cover and an additional river profile knickzone in the transition zone between the easterlies and the westerlies. Analysis of 10Be in quartz of river-born sand and of bedrock reveals that denudation correlates positively with the present-day rainfall pattern related to the easterlies. Denudation rates in the headwaters range from 0.14 mm/year in Northern Peru down to 0.05 mm/yr in Northern Chile (Kober et al., 2007). In addition, 10Be-based denudation rates reveal a decreasing trend from the Cordillera to the Pacific coast that positively correlates with the decreasing precipitation rate, irrespective of the nature of the bedrock. Interestingly, the 10Be analysis conducted in the Piura system reveals no influence of the episodic precipitation in relation to El Niño on the sediment production rates. In summary, the pattern of denudation rates together with morphometric observations and quantitative denudation rate estimates strongly hints at weathering being the driving but also limiting factor of denudation. Accordingly, in the western Peruvian Andes, sediment production and export are most probably controlled by the pattern and rate of precipitation. Kober, F., Ivy-Ochs, S., Schlunegger, F., Baur, H., Kubik, P. W., and Wieler, R. (2007). Denudation rates and a topography-driven rainfall threshold in northern Chile: Multiple cosmogenic nuclide data and sediment yield budgets. Geomorphology 83, 97-120.

Keratinocyte Motility Is Affected by UVA Radiation-A Comparison between Normal and Dysplastic Cells.

PubMed

Niculiţe, Cristina M; Nechifor, Marina T; Urs, Andreea O; Olariu, Laura; Ceafalan, Laura C; Leabu, Mircea

2018-06-07

UVA radiation induces multiple and complex changes in the skin, affecting epidermal cell behavior. This study reports the effects of UVA exposure on normal (HaCaT) and dysplastic (DOK) keratinocytes. The adherence, spreading and proliferation were investigated by time-lapse measurement of cell layer impedance on different matrix proteins. Prior to UVA exposure, the time required for adherence and spreading did not differ significantly for HaCaT and DOK cells, while spreading areas were larger for HaCaT cells. Under UVA exposure, HaCaT and DOK cells behavior differed in terms of movement and proliferation. The cells' ability to cover the denuded surface and individual cell trajectories were recorded by time-lapse videomicroscopy, during wound healing experiments. Dysplastic keratinocytes showed more sensitivity to UVA, exhibiting transient deficiencies in directionality of movement and a delay in re-coating the denuded area. The actin cytoskeleton displayed a cortical organization immediately after irradiation, in both cell lines, similar to mock-irradiated cells. Post-irradiation, DOK cells displayed a better organization of stress fibers, persistent filopodia, and new, stronger focal contacts. In conclusion, after UVA exposure HaCaT and DOK cells showed a different behavior in terms of adherence, spreading, motility, proliferation, and actin cytoskeleton dynamics, with the dyplastic keratinocytes being more sensitive.

Review of atmospheric ammonia data in the context of developing technologies, changing climate, and future policy evidence needs

NASA Astrophysics Data System (ADS)

Braban, Christine; Tang, Sim; Bealey, Bill; Roberts, Elin; Stephens, Amy; Galloway, Megan; Greenwood, Sarah; Sutton, Mark; Nemitz, Eiko; Leaver, David

2017-04-01

Ambient ammonia measurements have been undertaken both in the atmosphere to understand sources, concentrations at background and vulnerable ecosystems and for long term monitoring of concentrations. As a pollutant which is projected to increase concentration in the coming decades with significant policy challenges to implementing mitigation strategies it is useful to assess what has been measured, where and why. In this study a review of the literature, has shown that ammonia measurements are frequently not publically reported and in general not reposited in the open data centres, available for research. The specific sectors where measurements have been undertaken are: agricultural point source assessments, agricultural surface exchange measurements, sensitive ecosystem monitoring, landscape/regional studies and governmental long term monitoring. Less frequently ammonia is measured as part of an intensive atmospheric chemistry field campaign. Technology is developing which means a shift from chemical denuder methods to spectroscopic techniques may be possible, however chemical denuding techniques with off-line laboratory analysis will likely be an economical approach for some time to come. This paper reviews existing datasets from the different sectors of research and integrates them for a global picture to allow both a long term understanding and facilitate comparison with future measurements.

Chemical Properties of Brown Carbon Aerosol Generated at the Missoula Fire Sciences Laboratory

NASA Astrophysics Data System (ADS)

Washenfelder, R. A.; Womack, C.; Franchin, A.; Middlebrook, A. M.; Wagner, N.; Manfred, K.

2017-12-01

Aerosol scattering and absorption are still among the largest uncertainties in quantifying radiative forcing. Biomass burning is a major source of light-absorbing carbonaceous aerosol in the United States. These aerosol are generally classified into two categories: black carbon (graphitic-like aerosol that absorbs broadly across the ultraviolet and visible spectral regions) and brown carbon (organic aerosol that absorbs strongly in the ultraviolet and near-visible spectral regions). The composition, volatility, and chemical aging of brown carbon are poorly known, but are important to understanding its radiative effects. We deployed three novel instruments to the Missoula Fire Sciences Laboratory in 2016 to measure brown carbon absorption: a photoacoustic spectrometer, broadband cavity enhanced spectrometer, and particle-into-liquid sampler coupled to a liquid waveguide capillary cell. The instruments sampled from a shared inlet with well-characterized dilution and thermal denuding. We sampled smoke from 32 controlled burns of fuels relevant to western U.S. wildfires. We use these measurements to determine the volatility of water-soluble brown carbon, and compare this to the volatility of water-soluble organic aerosol and total organic aerosol. We further examine the wavelength-dependence of the water-soluble brown carbon absorption as a function of denuder temperature. Together this gives new information about the solubility, volatility, and chemical composition of brown carbon.

Dilution of 10Be in detrital quartz by earthquake-induced landslides: Implications for determining denudation rates and potential to provide insights into landslide sediment dynamics

NASA Astrophysics Data System (ADS)

West, A. Joshua; Hetzel, Ralf; Li, Gen; Jin, Zhangdong; Zhang, Fei; Hilton, Robert G.; Densmore, Alexander L.

2014-06-01

The concentration of 10Be in detrital quartz (10Beqtz) from river sediments is now widely used to quantify catchment-wide denudation rates but may also be sensitive to inputs from bedrock landslides that deliver sediment with low 10Beqtz. Major landslide-triggering events can provide large amounts of low-concentration material to rivers in mountain catchments, but changes in river sediment 10Beqtz due to such events have not yet been measured directly. Here we examine the impact of widespread landslides triggered by the 2008 Wenchuan earthquake on 10Beqtz in sediment samples from the Min Jiang river basin, in Sichuan, China. Landslide deposit material associated with the Wenchuan earthquake has consistently lower 10Beqtz than in river sediment prior to the earthquake. River sediment 10Beqtz decreased significantly following the earthquake downstream of areas of high coseismic landslide occurrence (i.e., with greater than ∼0.3% of the upstream catchment area affected by landslides), because of input of the 10Be-depleted landslide material, but showed no systematic changes where landslide occurrence was low. Changes in river sediment 10Beqtz concentration were largest in small first-order catchments but were still significant in large river basins with areas of 104-105 km. Spatial and temporal variability in river sediment 10Beqtz has important implications for inferring representative denudation rates in tectonically active, landslide-dominated environments, even in large basins. Although the dilution of 10Beqtz in river sediment by landslide inputs may complicate interpretation of denudation rates, it also may provide a possible opportunity to track the transport of landslide sediment. The associated uncertainties are large, but in the Wenchuan case, calculations based on 10Be mixing proportions suggest that river sediment fluxes in the 2-3 years following the earthquake increased by a similar order of magnitude in the 0.25-1 mm and the <0.25 mm size fractions, as determined from 10Beqtz mixing calculations and hydrological gauging, respectively. Such information could provide new insight into sediment transfer, with implications for secondary sediment-related hazards and for understanding the removal of mass from mountains.

The thermal history of the Karoo Moatize-Minjova Basin, Tete Province, Mozambique: An integrated vitrinite reflectance and apatite fission track thermochronology study

NASA Astrophysics Data System (ADS)

Fernandes, Paulo; Cogné, Nathan; Chew, David M.; Rodrigues, Bruno; Jorge, Raul C. G. S.; Marques, João; Jamal, Daud; Vasconcelos, Lopo

2015-12-01

The Moatize-Minjova Basin is a Karoo-aged rift basin located in the Tete Province of central Mozambique along the present-day Zambezi River valley. In this basin the Permian Moatize and Matinde formations consist of interbedded carbonaceous mudstones and sandstones with coal seams. The thermal history has been determined using rock samples from two coal exploration boreholes (ca. 500 m depth) to constrain the burial and exhumation history of the basin. Organic maturation levels were determined using vitrinite reflectance and spore fluorescence/colour. Ages and rates of tectonic uplift and denudation have been assessed by apatite fission track analysis. The thermal history was modelled by inverse modelling of the fission track and vitrinite reflectance data. The Moatize Formation attained a coal rank of bituminous coals with low to medium volatiles (1.3-1.7%Rr). Organic maturation levels increase in a linear fashion downhole in the two boreholes, indicating that burial was the main process controlling peak temperature maturation. Calculated palaeogeothermal gradients range from 59 °C/km to 40 °C/km. According to the models, peak burial temperatures were attained shortly (3-10 Ma) after deposition. Apatite fission track ages [146 to 84 Ma (Cretaceous)] are younger than the stratigraphic age. Thermal modelling indicates two episodes of cooling and exhumation: a first period of rapid cooling between 240 and 230 Ma (Middle - Upper Triassic boundary) implying 2500-3000 m of denudation; and a second period, also of rapid cooling, from 6 Ma (late Miocene) onwards implying 1000-1500 m of denudation. The first episode is related to the main compressional deformation event within the Cape Fold Belt in South Africa, which transferred stress northwards on pre-existing transtensional fault systems within the Karoo rift basins, causing tectonic inversion and uplift. During the Mesozoic and most of the Cenozoic the basin is characterized by very slow cooling. The second period of fast cooling and denudation during the Pliocene was likely related to the southward propagation of the East African Rift System into Mozambique.

Constraints on a Late Cretaceous uplift, denudation, and incision of the Grand Canyon region, southwestern Colorado Plateau, USA, from U-Pb dating of lacustrine limestone

NASA Astrophysics Data System (ADS)

Hill, Carol A.; Polyak, Victor J.; Asmerom, Yemane; P. Provencio, Paula

2016-04-01

The uplift and denudation of the Colorado Plateau is important in reconstructing the geomorphic and tectonic evolution of western North America. A Late Cretaceous (64 ± 2 Ma) U-Pb age for the Long Point limestone on the Coconino Plateau, which overlies a regional erosional surface developed on Permo-Triassic formations, supports unroofing of the Coconino Plateau part of Grand Canyon by that time. U-Pb analyses of three separate outcrops of this limestone gave ages of 64.0 ± 0.7, 60.5 ± 4.6, and 66.3 ± 3.9 Ma, which dates are older than a fossil-based, early Eocene age. Samples of the Long Point limestone were dated using the isotope dilution isochron method on well-preserved carbonates having high-uranium and low-lead concentrations. Our U-Pb ages on the Long Point limestone place important constraints on the (1) time of tectonic uplift of the southwestern Colorado Plateau and Kaibab arch, (2) time of denudation of the Coconino Plateau, and (3) Late Cretaceous models of paleocanyon incision west of, or across, the Kaibab arch. We propose that the age of the Long Point limestone, interbedded within the Music Mountain Formation in the Long Point area, represents a period of regional aggradation and a time of drainage blockage northward and eastward across the Kaibab arch, with possible diversion of northward drainage on the Coconino Plateau westward around the arch via a Laramide paleo-Grand Canyon.

Responsiveness of Coronary Arteries to Nitroglycerin under Hypoxia: The Importance of the Endothelium.

PubMed

Tawa, Masashi; Shimosato, Takashi; Sakonjo, Hiroshi; Okamura, Tomio

2017-01-01

Nitroglycerin is widely used as a coronary vasodilator in the treatment of ischemic heart diseases. This study investigated the influence of hypoxia on nitroglycerin-induced relaxation in endothelium-intact and -denuded rabbit, monkey, and porcine coronary arteries. Helically cut strips of coronary arteries were suspended in organ chambers, and isometric tension was recorded. Nitroglycerin concentration dependently relaxed endothelium-intact rabbit coronary arteries, which were not different under normoxic and hypoxic conditions. On the other hand, nitroglycerin-induced relaxation of endothelium-denuded arteries was significantly attenuated by hypoxia. Similarly, the relaxant response of endothelium-intact monkey coronary arteries to nitroglycerin was not affected by hypoxia, whereas that of endothelium-denuded arteries was impaired. As is the case with rabbit and monkey coronary arteries, exposure to hypoxia resulted in impaired relaxation by nitroglycerin in endothelium-denuded but not endothelium-intact porcine coronary arteries. These findings suggest that coronary endothelium plays a pivotal role in preventing the hypoxia-induced impairment of nitroglycerin responsiveness, regardless of the animal species. © 2017 S. Karger AG, Basel.

Methods to assess carbonaceous aerosol sampling artifacts for IMPROVE and other long-term networks.

PubMed

Watson, John G; Chow, Judith C; Chen, L W Antony; Frank, Neil H

2009-08-01

Volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) adsorb to quartz fiber filters during fine and coarse particulate matter (PM2.5 and PM10, respectively) sampling for thermal/optical carbon analysis that measures organic carbon (OC) and elemental carbon (EC). Particulate SVOCs can evaporate after collection, with a small portion adsorbed within the filter. Adsorbed organic gases are measured as particulate OC, so passive field blanks, backup filters, prefilter organic denuders, and regression methods have been applied to compensate for positive OC artifacts in several long-term chemical speciation networks. Average backup filter OC levels from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network were approximately 19% higher than field blank values. This difference is within the standard deviation of the average and likely results from low SVOC concentrations in the rural to remote environments of most IMPROVE sites. Backup filters from an urban (Fort Meade, MD) site showed twice the OC levels of field blanks. Sectioning backup filters from top to bottom showed nonuniform OC densities within the filter, contrary to the assumption that VOCs and SVOCs on a backup filter equal those on the front filter. This nonuniformity may be partially explained by evaporation and readsorption of vapors in different parts of the front and backup quartz fiber filter owing to temperature, relative humidity, and ambient concentration changes throughout a 24-hr sample duration. OC-PM2.5 regression analysis and organic denuder approaches demonstrate negative sampling artifact from both Teflon membrane and quartz fiber filters.

Field performance of a semi-continuous monitor for ambient PM2.5 water-soluble inorganic ions and gases at a suburban site

NASA Astrophysics Data System (ADS)

Young, Li-Hao; Li, Chiao-Hsin; Lin, Ming-Yeng; Hwang, Bing-Fang; Hsu, Hui-Tsung; Chen, Yu-Cheng; Jung, Chau-Ren; Chen, Kuan-Chi; Cheng, Dung-Hung; Wang, Ven-Shing; Chiang, Hung-Che; Tsai, Perng-Jy

2016-11-01

To reduce sampling artifacts and to improve time-resolved measurements of inorganic aerosol system, a recently commercialized semi-continuous In-situ Gas and Aerosol Composition (IGAC) monitoring system was evaluated against a reference annular denuder system (ADS; denuder/two-stage filter pack) at a suburban site over a year, during which the average PM2.5 was 37.0 ± 24.8 μg/m3. A suite of eight ions SO42-, NO3-, Cl-, NH4+, Na+, K+, Ca2+ and Mg2+ and two gases SO2 and NH3 were the target species. In comparison to the reference ADS method, the IGAC performed well in measuring the major ions SO42-, NO3- and NH4+, and the SO2. For those species, the linear slopes, intercepts and R2 values between the two methods all passed the performance evaluation criteria outlined by earlier similar studies. The performance of IGAC on Cl-, Na+, K+ and NH3 was marginally acceptable, whereas Ca2+ and Mg2+ could not be properly evaluated due to the low concentrations (<0.2 μg/m3) and hence inadequate amount of sample size. The ionic balance of the hourly IGAC samples averaged very close to unity, as did the daily ADS samples, though the former was considerably more variable than the latter. The overall performance of the IGAC has been shown to be comparable to other similar monitors and its improvements are discussed.

Bacterial SPOR domains are recruited to septal peptidoglycan by binding to glycan strands that lack stem peptides

PubMed Central

Yahashiri, Atsushi; Jorgenson, Matthew A.; Weiss, David S.

2015-01-01

Bacterial SPOR domains bind peptidoglycan (PG) and are thought to target proteins to the cell division site by binding to “denuded” glycan strands that lack stem peptides, but uncertainties remain, in part because septal-specific binding has yet to be studied in a purified system. Here we show that fusions of GFP to SPOR domains from the Escherichia coli cell-division proteins DamX, DedD, FtsN, and RlpA all localize to septal regions of purified PG sacculi obtained from E. coli and Bacillus subtilis. Treatment of sacculi with an amidase that removes stem peptides enhanced SPOR domain binding, whereas treatment with a lytic transglycosylase that removes denuded glycans reduced SPOR domain binding. These findings demonstrate unequivocally that SPOR domains localize by binding to septal PG, that the physiologically relevant binding site is indeed a denuded glycan, and that denuded glycans are enriched in septal PG rather than distributed uniformly around the sacculus. Accumulation of denuded glycans in the septal PG of both E. coli and B. subtilis, organisms separated by 1 billion years of evolution, suggests that sequential removal of stem peptides followed by degradation of the glycan backbone is an ancient feature of PG turnover during bacterial cell division. Linking SPOR domain localization to the abundance of a structure (denuded glycans) present only transiently during biogenesis of septal PG provides a mechanism for coordinating the function of SPOR domain proteins with the progress of cell division. PMID:26305949

Osteoarthritic bone marrow lesions almost exclusively colocate with denuded cartilage: a 3D study using data from the Osteoarthritis Initiative.

PubMed

Bowes, Michael A; McLure, Stewart Wd; Wolstenholme, Christopher Bh; Vincent, Graham R; Williams, Sophie; Grainger, Andrew; Conaghan, Philip G

2016-10-01

The aetiology of bone marrow lesions (BMLs) in knee osteoarthritis (OA) is poorly understood. We employed three-dimensional (3D) active appearance modelling (AAM) to study the spatial distribution of BMLs in an OA cohort and compare this with the distribution of denuded cartilage. Participants were selected from the Osteoarthritis Initiative progressor cohort with Kellgren-Lawrence scores ≥2, medial joint space narrowing and osteophytes. OA and ligamentous BMLs and articular cartilage were manually segmented. Bone surfaces were automatically segmented by AAM. Cartilage thickness of <0.5 mm was defined as denuded and ≥0.5-1.5 mm as severely damaged. Non-quantitative assessment and 3D population maps were used for analysing the comparative position of BMLs and damaged cartilage. 88 participants were included, 45 men, mean age (SD) was 61.3 (9.9) years and mean body mass index was 31.1 (4.6) kg/m(2). 227 OA and 107 ligamentous BMLs were identified in 86.4% and 73.8% of participants; OA BMLs were larger. Denuded cartilage was predominantly confined to a central region on the medial femur and tibia, and the lateral facet of the trochlear femur. 67% of BMLs were colocated with denuded cartilage and a further 21% with severe cartilage damage. In the remaining 12%, 25/28 were associated with cartilage defects. 74% of all BMLs were directly opposing (kissing) another BML across the joint. There was an almost exclusive relationship between the location of OA BML and cartilage denudation, which itself had a clear spatial pattern. We propose that OA, ligamentous and traumatic BMLs represent a bone response to abnormal loading. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

First report of (U-Th)/He thermochronometric data across Northeast Japan Arc: implications for the long-term inelastic deformation

NASA Astrophysics Data System (ADS)

Sueoka, Shigeru; Tagami, Takahiro; Kohn, Barry P.

2017-06-01

(U-Th)/He thermochronometric analyses were performed across the southern part of the Northeast Japan Arc for reconstructing the long-term uplift and denudation history in the region. Apatite (U-Th-Sm)/He ages ranged from 64.3 to 1.5 Ma, while zircon (U-Th)/He ages ranged between 39.6 and 11.0 Ma. Apatite (U-Th-Sm)/He ages showed obvious contrast among the morphostructural provinces; older ages of 64.3-49.6 Ma were obtained in the Abukuma Mountains on the fore-arc side, whereas younger ages of 11.4-1.5 Ma were determined in the Ou Backbone Range (OBR) along the volcanic front and the Asahi Mountains on the back-arc side. The age contrasts are basically interpreted to reflect the differences in the uplift and the denudation histories of the provinces considering the thermal effects of magmatism and timing of the known uplift episodes. Denudation rates were calculated to be <0.1 mm/year in the Abukuma Mountains, 0.1 to 1 mm/year in the Ou Backbone Range, and 0.1 to 0.3 mm/year in the Asahi Mountains. The denudation rates tend to increase from the mountain base to the ridges in the OBR (and the Asahi Mountains). This relationship shows a contrast with the previous findings in fault-block mountains in the Southwest (SW) Japan Arc, where the highest denudation rates were estimated near fault(s) along the base(s). This observation might reflect a difference in mountain uplift mechanisms between the NE and the SW Japan Arcs and imply that thermochronometric approaches are useful for constraining uplift and denudation histories at the scale of an island arc, as well as continental orogens. However, careful discussion of magmatic thermal effects is required.[Figure not available: see fulltext.

Concentration characteristics of VOCs and acids/bases in the gas phase and water-soluble ions in the particle phase at an electrical industry park during construction and mass production.

PubMed

Tsai, Jiun H; Huang, Yao S; Shieh, Zhu X; Chiang, Hung L

2011-01-01

The electronics industry is a major business in the Central Taiwan Science Park (CTSP). Particulate samples and 11 water-soluble ionic species in the particulate phase were measured by ionic chromatography (IC). Additionally, acid and base gases were sampled by denuder absorption and analyzed by IC. Volatile organic compounds (VOCs) were collected in stainless-steel canisters four times daily and analyzed via gas chromatography/mass spectrometry. Ozone formation potential (OFP) was measured using maximum increment reactivity. In addition, airborne pollutants during (1) construction and (2) mass production were measured. Particulate matter concentration did not increase significantly near the optoelectronic plant during construction, but it was higher than during mass production. SO(2), HNO(2) and NH(3) were the dominant gases in the denuder absorption system. Nitrate, sulfate, and ammonium ions predominated both in PM(2.5) and PM(10-2.5); but calcium ion concentration was significantly higher in PM(10-2.5) samples during construction. Toluene, propane, isopentane, and n-butane may have come from vehicle exhaust. Construction equipment emitted high concentrations of ethylbenzene, m-xylene, p-xylene, o-xylene, 1,2,4-trimethylbenzene, and toluene. During mass production, methyl ethyl ketone), acetone and ethyl acetate were significantly higher than during construction, although there was continuous rain. The aromatic group constituted >50% of the VOC concentration totals and contributed >70% of OFP.

Late Cenozoic flexural deformation of the middle U.S. Atlantic passive margin

NASA Technical Reports Server (NTRS)

Pazzaglia, Frank J.; Gardner, Thomas, W.

1994-01-01

Despite the century-long recognition of regional epeirogeny along the middle Atlantic passive margin, relatively few studies have focused on understanding postrift uplift mechanisms. Here, we demonstrate that epeirogenic uplift of the central Appalachian Piedmont and subsidence of the Salisbury Embayment represent first-order, flexural isostatic processes driven by continental denudation and offshore deposition. Our results show that regional epeirogenic processes, present on all Atlantic-type passive margins, are best resolved by specific stratigraphic and geomorphic relationships, rather than topography. A simple one-dimensional geodynamic model, constrained by well-dated Baltimore Canyon trough, Coastal Plain, and lower Susquehanna River (piedmont) stratigraphy, simulates flexural deforamtion of the U.S. Atlantic margin. The model represents the passive margin lithosphree as a uniformly thick elastic plate, without horizontal compressive stresses, that deforms flexurally under the stress of strike-averaged, vertically applied line loads. Model results illustrate a complex interaction among margin stratigraphy and geomorphology, the isostatic repsonse to denudational and depositional processes, and the modulating influence of exogenic forces such as eustasy. The current elevation, with respect to modern sea level, of fluvial terraces and correlateive Coastal Plain deposits or unconformities is successfully predicted through the synthesis of paleotopography, eustatic change, and margin flexure. Results suggest that the middle U.S. Atlantic margin landward of East Coast Magnetic Anomaly is underlain by lithoshpere with an average elastic thickness of 40 km (flexural rigidity, D = 4 X 10(exp 23) N m), the margin experience an average, long-term denudation rate of approximately 10m/m.y., and the Piedmont has been flexurally upwaped between 35 and 130 meters in the last 15 m.y. Long term isostatic continental uplift resulting rom denudation and basin subsidence resulting rom sediment loading are accomodated primately by a convex-up flexural hinge, physiographically represented by the Fall Zone. Our results elucidate an inherent danger in using topography alone to constrain late-stage passive margin deformation mechanisms. Only through careful synthesis of field stratigraphic and geomorphic elements such as fluvial terraces, Coastal Plain deposits, and offshore stratigraphy can age control be extended from the offshore depositional setting to the erosionally dominated continent. This sudy demonstrates that despite a relatively subdued topography, the middle U.S. Atlantic margin experiences progressive flexural isostatic deformation similar to that proposed for high-relief margins characterized by great escarpments. Thus margin topographic diversity remains a function of other factors, such as lithospheric composition and/or structure, supracrustal stratigraphy and structure, degree of drainage integration, drainage divide migration and climate.

Acidity of fine sulfate particles at Great Smokey Mountains National Park

DOE Office of Scientific and Technical Information (OSTI.GOV)

Day, D.; Malm, W.C.; Kreidenweis, S.

1995-12-31

The acidity of ambient particles is of interest from the perspectives of human health, visibility, and ecology. This paper reports on the acidity of fine (< 2.5{mu}m) particles measured during August 1994 at Look Rock observation tower in Great Smokey Mountains National Park. This site is located at latitude 35{degrees} 37 feet 56 inches, longitude 83{degrees} 56 feet 32 inches, and at an elevation of 808m above sea level. All samples were collected using the IMPROVE (Interagency Monitoring of Protected Visual Environments) sampler. The sampling periods included: (1) 4-hour samples collected three times daily with starting times of 8:00 AM,more » 12:00 noon, and 4:00 PM; (2) 12-hour samples collected twice daily with starting times of 8:00 AM and 8:00 PM (all times reported are eastern daylight savings time). The IMPROVE sampler, collecting 4-hour samples, employed a citric acid/glycerol coated annular denuder to remove ammonia gas while the 12-hour sampler did not use a citric acid denuder. The intensive monitoring effort, conducted during August 1994, showed that: (1) the fine aerosol mass is generally dominated by sulfate and its associated water; (2) there was no statistically significant difference in average sulfate concentration between the 12-hour samples nor was there a statistically significant difference in average sulfate concentration between the 4-hour samples; (3) the aerosol is highly acidic, ranging from almost pure sulfuric acid to pure ammonium bisulfate, with an average molar ammonium ion to sulfate ratio of about 0.75 which suggests the ambient sulfate aerosol was a mixture of ammonium bisulfate and sulfuric acid; and (4) there was no statistically significant diurnal variation in particle acidity nor was there a statistically significant difference in particle acidity between the 4 hour samples.« less

Aerosol counterflow two-jets unit for continuous measurement of the soluble fraction of atmospheric aerosols.

PubMed

Mikuska, Pavel; Vecera, Zbynek

2005-09-01

A new type of aerosol collector employing a liquid at laboratory temperature for continuous sampling of atmospheric particles is described. The collector operates on the principle of a Venturi scrubber. Sampled air flows at high linear velocity through two Venturi nozzles "atomizing" the liquid to form two jets of a polydisperse aerosol of fine droplets situated against each other. Counterflow jets of droplets collide, and within this process, the aerosol particles are captured into dispersed liquid. Under optimum conditions (air flow rate of 5 L/min and water flow rate of 2 mL/min), aerosol particles down to 0.3 microm in diameter are quantitatively collected in the collector into deionized water while the collection efficiency of smaller particles decreases. There is very little loss of fine aerosol within the aerosol counterflow two-jets unit (ACTJU). Coupling of the aerosol collector with an annular diffusion denuder located upstream of the collector ensures an artifact-free sampling of atmospheric aerosols. Operation of the ACTJU in combination with on-line detection devices allows in situ automated analysis of water-soluble aerosol species (e.g., NO2-, NO3-)with high time resolution (as high as 1 s). Under the optimum conditions, the limit of detection for particulate nitrite and nitrate is 28 and 77 ng/m(3), respectively. The instrument is sufficiently rugged for its application at routine monitoring of aerosol composition in the real time.

Carbon and water, the energy for weathering and chemical denudation

NASA Astrophysics Data System (ADS)

Perdrial, J. N.; Rasmussen, C.; McIntosh, J. C.; Zapata, X.; Harpold, A. A.; Vazquez, A.; Porter, C. M.; Brooks, P. D.; Meixner, T.; Mitra, B.; Troch, P. A.; Chorover, J.

2012-12-01

Development of predictive relations between climatic forcing and geochemical weathering is a priority for Critical Zone (CZ) research. We postulate that quantification of climatic drivers, by their integration into a single currency that accounts for energy associated with water and carbon fluxes, is predictive of catchment solute loss associated with incongruent landscape dissolution (i.e. chemical denudation). This hypothesis was tested using meteorological data incorporated into a model of effective energy and mass transfer (EEMT, kJ -2 y-1,[1]) to determine if EEMT is a useful predictor of chemical denudation observed at different scales of CZ observation (pedon to watershed). Water, carbon and lithogenic element flux data were collected from several snow-dominated forested mountain catchments underlain by rhyolite in the Santa Catalina Mountains - Jemez River Basin (SCM-JRB) CZ Observatory during the years 2010-2012. Annual catchment scale fluxes for major and trace lithogenic elements (Na, Mg, Si, Ca and lanthanides a.k.a. REE) are positively correlated (r2 between 0.6 and 0.9) with annual EEMT values (i.e., CZ inputs of energy associated with carbon and water). Both differences in climatic conditions as well as catchment characteristics (i.e. aspect) modulate the magnitude of EEMT and, corresponding chemical denudation. Furthermore, CZ EEMT store (EEMTin - EEMTout), the energy available for weathering, shows likewise positive correlations with the loss of lithogenic elements, confirming that CZ water and carbon fluxes can be used to predict chemical denudation.[1] Rasmussen et al. (2010). An open system framework for integrating critical zone structure and function. Biogeochemistry. 102, 15-29.

Surface denudation rate of gypsum in Sicily

NASA Astrophysics Data System (ADS)

Madonia, Giuliana; Vattano, Marco; Di Maggio, Cipriano; De Waele, Jo

2016-04-01

Studies on surface denudation rate of karst rocks were carried out for many years with different methods, although researches on limestones are much more numerous than those on gypsum. In Sicily the most large and complete Messinian evaporite succession of Gruppo Gessoso - Solfifero outcrops and since 1993-1994 surface denudation measurements were performed on different types of gypsum by the Micro-Erosion Meter (M.E.M.) method. MEM stations were placed on natural sites representing different lithological features of gypsum outcrops of the Island: 1) selenite gypsum with centimetre-sized crystals; 2) selenite gypsum with sub-centimetre crystals; 3) gypsum arenite; 4) microcrystalline gypsum; and 5) gypsum laminite (balatino type). The measuring stations are positioned in three localities in western and central Sicily: Santa Ninfa (Trapani), Ciminna (Palermo) and Campofranco (Caltanissetta). The average lowering rates vary in the different lithofacies: from 0.25 mm yr-1 in microcrystalline gypsum to 0.74 mm yr-1 in selenite gypsum with centimetre-sized crystals. The average surface denudation rates are 0.40 mm yr-1 in balatino gypsum and gypsum arenite, and 0.37 mm yr-1 in selenite gypsum with sub-centimetre crystals. These different values are connected to several factors such as: rock texture, dip of gypsum surfaces, climatic conditions, troubles on the measurement sites (e.g.: presence of lichens, soil, remains of vegetation, etc.). The aim of this paper is to show the results of roughly twenty years of experimental measurements, and to compare the surface denudation rate of gypsum in Sicily with those of other evaporite areas characterised by different climatic settings.

Rates and patterns of late Cenozoic denudation in the northernmost Atlantic Coastal Plain and Piedmont

USGS Publications Warehouse

Stanford, S.D.; Ashley, G.M.; Russell, E.W.B.; Brenner, G.J.

2002-01-01

Topography of a 2800 km2 section of the U.S. Atlantic Coastal Plain and Piedmont is reconstructed at five times from the late Miocene to the Holocene. The reconstructions are based on mapping of fluvial, colluvial, and marginal-marine deposits that are dated by radiocarbon, palynostratigraphy, and correlation to adjacent glacial and marine units. Denudation rates and patterns are calculated by subtracting successive topographies, with 60 m horizontal resolution and 6 m vertical resolution. The overall late Miocene to Holocene denudation rate of 10 m/m.y. is similar to other estimates of long-term denudation in the region. The overall rate resolves spatially into a wide range of local rates, varying from a minimum of ???0.2 m/m.y. on residual uplands to as high as 600 m/m.y. in glacially rerouted stream channels. The distribution of local rates shows that denudation is accomplished by stream incision in response to long-term glacio-eustatic decline, followed by slope retreat into residual uplands from the incised channels. Slope retreat replaces the uplands with pediments and straths. Pediment landforms and sediments, and observation of modern scarps and valley heads, indicate that groundwater seepage from the base of residual uplands is an important mechanism of slope retreat. This process is self-limiting because as the volume of residual upland is reduced, seepage diminishes and slope retreat slows until small residuals undergo little or no further reduction. Thus, relict topography is preserved even as most of the landscape actively erodes.

Elemental and Organic Carbon Measurements at the Kosetice Observatory, Czech Republic within EU Projects in 2009-2014

NASA Astrophysics Data System (ADS)

Vana, M.; Holubova, A.; Cech, J.

2016-12-01

Carbonaceous aerosol (TC) is a complex mixture of many organics (OC fraction) and elemental carbon (EC). EC is a product of anthropogenic activities, especially incomplete combustion of fossil fuels by transport, heating, power plants, wood and biomass burning and agriculture activities. EC could have larger health impact than other PM constituents (Cassee et al., 2013). Carbonaceous aerosols also play an important role in climate change (Boucher et al., 2013). Kosetice Observatory, operated by the Czech Hydrometeorological Institute has been carrying out long-term air quality monitoring at the background scale the Czech Republic since 1988. Regular EC-OC measurement has been implementing within EU-projects EUSAAR and ACTRIS since 2009. Sampling frequency is every 6th day in fraction PM2,5 on 2 quartz-fibre filters. Since October 2011 the sampling on filters has been implementing behind the denuder catching the organic vapor. Amount of OC on back quartz fiber filter represents positive artifact by measurement without denuder and negative artifact by measurements with denuder. The analytical method is thermal-optical analysis. The samples are analyzed in CHMI Central Laboratories in Prague-Libuš using EC-OC Sunset Lab Dual Analyzer. Charring correction is made by laser transmission monitoring. Slightly decreasing tendency of EC-OC was found in the period under review (2009-2014). The mean annual concentration of total carbon (TC) in PM2,5 was 3,73 µg.m-3. The figure for elemental carbon (0,5 µg.m-3) represents the mean annual ratio of 13% on TC. EC-OC concentrations follow an annual course that reflects their emission levels, i.e. with maximums in winter and minimums in summer. The seasonal variation of EC/TC ratio ranges between 9,6 (summer) - 14,2% (winter). Mean TC ratio on PM2,5 total mass in the period under review was 29%, the highest ratios reached 50%. EC participated on PM2,5 total mass by 3,5% in average. 3D trajectories were used for sector analysis of measured EC-OC data (NILU, 2016). The highest concentrations are recorded in situations when air masses reach the territory of the Czech Republic from the north-eastern directions or the local air masses prevailing. The differences between sectors are much larger in the cold period of the year.

Comparison of low cost measurement techniques for long-term monitoring of atmospheric ammonia.

PubMed

Sutton, M A; Miners, B; Tang, Y S; Milford, C; Wyers, G P; Duyzer, J H; Fowler, D

2001-10-01

An inter-comparison of techniques for long-term sampling of atmospheric ammonia (NH3) was conducted with a view to establishing a national network with > 50 sites. Key requirements were for: a low cost system, simplicity and durability to enable a postal exchange with local site operators, a precision of < +/- 20% for monthly sampling at expected NH3 concentrations of 1-2 micrograms m-3, a detection limit sufficient to resolve the small NH3 concentrations (< 0.2 microgram m-3) expected in remote parts of the UK, and a quantitative means to establish quality control. Five sampling methods were compared: A, a commercially available membrane diffusion tube (exposed in triplicate), with membranes removed immediately after sampling; B, the above method, with the membranes left in place until analysis; C, open-ended diffusion tubes (exposed with 4 replicates); D, a new active sampling diffusion denuder system; and E, an active sampling bubbler system. Method D consisted of two 0.1 m acid coated glass denuders in series with sampling at approximately 0.3 l min-1. These methods were deployed at 6 locations in the UK and the Netherlands and compared against reference estimates. Method D was the most precise and sensitive of the techniques compared, with a detection limit of < 0.1 microgram m-3. The bubbler provided a less precise estimate of NH3 concentration, and also suffered several practical drawbacks. The diffusion tubes were found to correlate with the reference at high concentrations (> 3 micrograms m-3), but were less precise and overestimated NH3 at smaller concentrations. Of the passive methods, A was the most precise and C the least precise. On the basis of the results, method D has been implemented in the national network, together with application of method A to explore spatial variability in regions with expected high NH3 concentrations.

Impact of glaciations on the long-term erosion in Southern Patagonian Andes

NASA Astrophysics Data System (ADS)

Simon-Labric, Thibaud; Herman, Frederic; Baumgartner, Lukas; Shuster, David L.; Braun, Jean; Reiners, Pete W.; Valla, Pierre G.; Leuthold, Julien

2014-05-01

The Southern Patagonian Andes are an ideal setting to study the impact of Late-Cenozoic climate cooling and onset of glaciations impact on the erosional history of mountain belts. The lack of tectonic activity during the last ~12 Myr makes the denudation history mainly controlled by surface processes, not by tectonics. Moreover, the glaciations history of Patagonia shows the best-preserved records within the southern hemisphere (with the exception of Antarctica). Indeed, the dry climate on the leeward side of Patagonia and the presence of lava flows interbedded with glacial deposits has allowed an exceptional preservation of late Cenozoic moraines with precise dating using K-Ar analyses on lava flow. The chronology of moraines reveals a long history covering all the Quaternary, Pliocene, and up to the Upper Miocene. The early growth of large glaciers flowing on eastern foothills started at ~7-6 Myr, while the maximum ice-sheet extent dates from approximately 1.1 Myr. In order to quantify the erosion history of the Southern Patagonian Andes and compare it to the glaciations sediment record, we collected samples along an age-elevation profile for low-temperature thermochronology in the eastern side of the mountain belt (Torres del Paine massif). The (U-Th)/He age-elevation relationship shows a clear convex shape providing an apparent long-term exhumation rate of ~0.2 km/Myr followed by an exhumation rate increase at ~6 Myr. Preliminary results of 4He/3He thermochronometry for a subset of samples complete the erosion history for the Plio-Pleistocene epoch. We used inverse procedure predicting 4He distributions within an apatite grain using a radiation-damage and annealing model to quantify He-diffusion kinetics in apatite. The model also allows quantifying the impact of potential U-Th zonation throughout each apatite crystal. Inversion results reveal a denudation history composed by a pulse of denudation at ~6 Ma, as suggested by the age-elevation relationship, followed by a decrease in denudation rate to very low value (<0.1 km/Myr) and late-stage exhumation phase at ~1 km/Myr for the last ~2 Myr. Our (U-Th)/He and 4He/3He data demonstrate a tight connection between the glaciation history from moraines record and long-term erosion rates derived from low-temperature thermochronology. These results highlight the high sensitivity of the Southern Patagonian Andes to the progressive Late-Cenozoic climate cooling and the strong glacial imprint on erosion history and landscape evolution since the Late Miocene. Indeed, we interpret the observed increase in erosion at ~6 Myr as the landscape response to the onset of the Patagonian ice cap, while the inferred recent increase in erosion rates may reflect the intensification of the climate cooling since the Plio-Pleistocene.

Circulating platelet aggregates damage endothelial cells in culture.

PubMed

Aluganti Narasimhulu, Chandrakala; Nandave, Mukesh; Bonilla, Diana; Singaravelu, Janani; Sai-Sudhakar, Chittoor B; Parthasarathy, Sampath

2017-06-01

Presence of circulating endothelial cells (CECs) in systemic circulation may be an indicator of endothelial damage and/or denudation, and the body's response to repair and revascularization. Thus, we hypothesized that aggregated platelets (AgPlts) can disrupt/denude the endothelium and contribute to the presence of CEC and EC-derived particles (ECDP). Endothelial cells were grown in glass tubes and tagged with/without 0.5 μm fluorescent beads. These glass tubes were connected to a mini-pump variable-flow system to study the effect of circulating AgPlts on the endothelium. ECs in glass tube were exposed to medium alone, nonaggregated platelets (NAgPlts), AgPlts, and 90 micron polystyrene beads at a flow rate of 20 mL/min for various intervals. Collected effluents were cultured for 72 h to analyze the growth potential of dislodged but intact ECs. Endothelial damage was assessed by real time polymerase chain reaction (RT-PCR) for inflammatory genes and Western blot analysis for von Willebrand factor. No ECs and ECDP were observed in effluents collected after injecting medium alone and NAgPlts, whereas AgPlts and Polybeads drastically dislodged ECs, releasing ECs and ECDP in effluents as the time increased. Effluents collected when endothelial cell damage was seen showed increased presence of von Willebrand factor as compared to control effluents. Furthermore, we analyzed the presence of ECs and ECDPs in heart failure subjects, as well as animal plasma samples. Our study demonstrates that circulating AgPlts denude the endothelium and release ECs and ECDP. Direct mechanical disruption and shear stress caused by circulating AgPlts could be the underlying mechanism of the observed endothelium damage. Copyright © 2017 Elsevier Inc. All rights reserved.

Development and application of compact denuder sampling techniques with in situ derivatization followed by gas chromatography-mass spectrometry for halogen speciation in volcanic plumes

NASA Astrophysics Data System (ADS)

Rüdiger, Julian; Bobrowski, Nicole; Hoffmann, Thorsten

2015-04-01

Volcanoes are a large source for several reactive atmospheric trace gases including sulphur and halogen containing species. The detailed knowledge of volcanic plume chemistry can give insights into subsurface processes and can be considered as a useful geochemical tool for monitoring of volcanic activity, especially halogen to sulphur ratios (e.g. Bobrowski and Giuffrida, 2012; Donovan et al., 2014). The reactive bromine species bromine monoxide (BrO) is of particular interest, because BrO as well as SO2 are readily measurable by UV spectrometers at a safe distance. Furthermore it is formed in the plume by a multiphase reaction mechanism under depletion of ozone in the plume. The abundance of BrO changes as a function of the reaction time and therefore distance from the vent as well as the spatial position in the plume. Due to the lack of analytical approaches for the accurate speciation of certain halogens (HBr, Br2, Br, BrCl, HOBr etc.) there are still uncertainties about the magnitude of volcanic halogen emissions and in particular their specificationtheir species and therefore also in the understanding of the bromine chemistry in volcanic plumes (Bobrowski et al., 2007). In this study, the first application of a 1,3,5-trimethoxybenzene (1,3,5-TMB)-coated gas diffusion denuder (Huang and Hoffmann, 2008) on volcanic gases proved to be suitable to collect selectively gaseous bromine species with oxidation states of +1 or 0 (Br2 and BrO(H)), while being ignorant to HBr (OS -1). The reaction of 1,3,5-TMB with bromine gives 1-bromo-2,4,6-trimethoxybenzene (1-bromo-2,4,6-TMB) - other halogens give corresponding products. The diffusion denuder technique allows sampling of gaseous compounds exclusively without collecting particulate matter. Choosing a flow rate of 500 mL-min-1 and a denuder length of 0.5 m a nearly quantitative collection efficiency was achieved. Solvent elution of the derivatized analytes and subsequent analysis with gas chromatography-mass spectrometry gives a limit of detection below 1 ng of bromine. The method was applied on volcanic gas plumes at Mt. Etna and Mt. Stromboli in Italy in July 2014 and on fumarolic gas emissions at Mt. Lastarria in Chile in November 2014. The results show significant amounts of the concerning bromine species (lower ppb range). Comprehensive data evaluation and comparison with results of impinger extraction with NaOH solution as well as chamber experiments are still in progress. References Bobrowski, N. and G. Giuffrida: Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006-2009. Solid Earth, 3, 433-445, 2012 Bobrowski, N., R. von Glasow, A. Aiuppa, S. Inguaggiato, I. Louban, O. W. Ibrahim and U. Platt: Reactive halogen chemistry in volcanic plumes. J. Geophys. Res., 112, 2007 Donovan A., V. Tsanev, C. Oppenheimer and M. Edmonds: Reactive halogens (BrO and OClO) detected in the plume of Soufrière Hills Volcano during an eruption hiatus. Geochem. Geophys. Geosyst., 15, 3346-3363, 2014 Huang, R.-J. and T. Hoffmann: A denuder-impinger system with in situ derivatization followed by gas chromatography-mass spectrometry for the determination of gaseous iodine-containing halogen species. Journal of Chromatography A, 1210, 135-141, 2008

Comparative study of He bubble formation in nanostructured reduced activation steel and its coarsen-grained counterpart

NASA Astrophysics Data System (ADS)

Liu, W. B.; Zhang, J. H.; Ji, Y. Z.; Xia, L. D.; Liu, H. P.; Yun, D.; He, C. H.; Zhang, C.; Yang, Z. G.

2018-03-01

High temperature (550 °C) He ions irradiation was performed on nanostructured (NS) and coarsen-grained (CG) reduced activation steel to investigate the effects of GBs/interfaces on the formation of bubbles during irradiation. Experimental results showed that He bubbles were preferentially trapped at dislocations and/or grain boundaries (GBs) for both of the samples. Void denuded zones (VDZs) were observed in the CG samples, while VDZs near GBs were unobvious in NS sample. However, both the average bubble size and the bubble density in peak damage region of the CG sample were significantly larger than that observed in the NS sample, which indicated that GBs play an important role during the irradiation, and the NS steel had better irradiation resistance than its CG counterpart.

A continuous analyzer for soluble anionic constituents and ammonium in atmospheric particulate matter.

PubMed

Al-Horr, Rida; Samanta, Gautam; Dasgupta, Purnendu K

2003-12-15

A new continuous soluble particle collector (PC) that does not use steam is described. Preceded by a denuder and interfaced with an ion chromatograph, this compact collector (3 in. o.d., approximately 5 in. total height) permits collection and continuous extraction of soluble components in atmospheric particulate matter. The PC is mounted atop a parallel plate wetted denuder for removal of soluble gases. The soluble gas denuded air enters the PC through an inlet. One version of the PC contained an integral cyclone-like inlet. For this device, penetration of particles as a function of size was characterized. In the simpler design, the sampled air enters the PC through a nozzle, and deionized water flows through a capillary tube placed close to the exit side of the nozzle by Venturi action or is forcibly pumped. Some growth of the aerosol occurs in the highly humid mist-chamber environment, but the dominant aerosol capture mechanism involves capture by the water film that forms on the hydrophobic PTFE membrane filter that constitutes the top of the PC and the airflow exit. Water drops coalesce on the filter and fall below into a purpose-machined cavity equipped with a liquid sensor. The water and the dissolved constituents are aspirated by a pump onto serial cation and anion preconcentrator columns. NH4+ captured by the cation preconcentrator is eluted with NaOH and is passed across an asymmetric membrane device. NH3 diffuses from the alkaline donor stream into a deionized water flowing countercurrent; the conductivity of the latter provides a measure of ammonium. The anions on the anion preconcentrator column are eluted and measured by a fully automated ion chromatography system. The total system thus provides automated semicontinuous measurement of soluble anions and ammonium. With a 15 min analytical cycle and a sampling rate of 5 L/min, the limit of detection (LOD) for ammonium is 8 ng/m3 and those for sulfate, nitrate, and oxalate are < or = 0.1 ng/m3. The system has been extensively field tested.

The effect of topography and rock type on soil cation contents and stream solute and phosphorus concentrations of streams in the southwestern Brazilian Amazon basin.

NASA Astrophysics Data System (ADS)

Biggs, T. W.; Dunne, T.; Holmes, K.; Martinelli, L. A.

2001-12-01

Topography plays an important role in determining soil properties, stream solute concentrations and landscape denudation rates. Stallard (1985) suggested that catchment denudation rates should depend on soil thickness. Areas with low slopes are limited by the rate of transport of sediment, and typically contain thick soils that prevent interaction of stream waters with underlying bedrock [Stallard 1985]. Steep areas typically have thin soils, but a lower hydrologic residence time that may prevent soil water from coming into thermodynamic equilibrium with the soil-rock complex. In a survey of streams in the Brazilian Amazon basin, Biggs et al. (2001) found that stream solute concentrations correlate with soil cation contents in the humid tropics, but the mechanism underlying the correlation has not been determined. We combine chemical analyses of water samples from ~40 different streams with soil surveys, geology maps, and a 100m resolution DEM to examine the relationship between topography, rock type, soil cation contents, and stream solute concentrations in the Brazilian Amazon state of Rondônia. The basins are all more than 60% forested at the time of stream sampling and lie on granite-gneiss rocks, tertiary sediments, or sandstone. The catchment-averaged slope correlates positively with both soil cation contents and stream concentrations of P, Na, Ca, Mg, K, Si, ANC, and pH. Though we have no data about the relationship between soil depth and average slope, we assume an inverse correlation, so the data demonstrates that thick soils yield lower solute concentrations. Stream concentrations of Ca, Mg, ANC and pH reach a maximum at intermediate average slopes (3 degrees), suggesting that denudation rates may increase with slope up to a maximum, when the catchment becomes limited by the weathering rate of the basement rock. Catchments on mica-schists or mafic rocks have low average slopes and higher concentrations of Ca, Mg, Si, ANC, and pH than catchments on granite-gneiss, tertiary sediments or sandstone.

A Novel Wounding Device Suitable for Quantitative Biochemical Analysis of Wound Healing and Regeneration of Cultured Epithelium

PubMed Central

Lan, Rongpei; Geng, Hui; Hwang, Yoon; Mishra, Pramod; Skloss, Wayne L.; Sprague, Eugene A.; Saikumar, Pothana; Venkatachalam, Manjeri

2010-01-01

We describe the fabrication and use of an in vitro wounding device that denudes cultured epithelium in patterns designed to leave behind strips or islands of cells sufficiently narrow or small to ensure that all remaining cells become rapidly activated and then migrate, dedifferentiate and proliferate in near synchrony. The design ensures that signals specific to regenerating cells do not become diluted by quiescent differentiated cells that are not affected by wound induced activation. The device consists of a flat circular disk of rubber engraved to produce alternating ridges and grooves in patterns of concentric circles or parallel lines. The disk is mounted at the end of a pneumatically controlled piston assembly. Application of controlled pressure and circular or linear movement of the disk on cultures produced highly reproducible wounding patterns. The near synchronous regenerative activity of cell bands or islands permitted the collection of samples large enough for biochemical studies to sensitively detect alterations involving mRNA for several early response genes and protein phosphorylation in major signaling pathways. The method is versatile, easy to use and reproducible, and should facilitate biochemical, proteomic and genomic studies of wound induced regeneration of cultured epithelium. PMID:20230600

Ultra structural changes occurring in duct ectasia and periductal mastitis and their significance in etiopathogenesis.

PubMed

Ramalingam, Kirithiga; Vuthaluru, Seenu; Srivastava, Anurag; Dinda, Amit Kumar; Dhar, Anita

2017-01-01

Duct ectasia (DE) and periductal mastitis (PDM) are the most common benign breast conditions seen in women. The etiopathogenesis of these entities is still not clear and most of the theories regarding the causation are based on the histological features as seen on light microscopy. The ultramicroscopic features associated with these conditions that may give more insight to the etiopathogenesis are unknown. To study the ultrastructural changes occurring in mammary duct cones in patients with DE and PDM using Transmission Electron Microscopic (TEM). Major ducts removed by radical duct excision from 21 patients with final histopathological diagnosis of DE and PDM were subjected to TEM study with 2 normal duct samples as controls. The TEM features of DE were denudation of the epithelial cells with focal loss of microvilli, widening of the inter-epithelial junctions with focal disruption of the T bars, periductal collagenisation without inflammation, and features suggestive of Epithelial Mesenchymal Transition (EMT). PDM features are intact epithelial lining with proliferative epithelium and periductal collagenisation with inflammation. Based on the TEM findings, we suggest that DE and PDM are two different entities. EMT a novel finding observed in DE in this study.

Ultra structural changes occurring in duct ectasia and periductal mastitis and their significance in etiopathogenesis

PubMed Central

Ramalingam, Kirithiga; Vuthaluru, Seenu; Srivastava, Anurag; Dinda, Amit Kumar; Dhar, Anita

2017-01-01

Introduction Duct ectasia (DE) and periductal mastitis (PDM) are the most common benign breast conditions seen in women. The etiopathogenesis of these entities is still not clear and most of the theories regarding the causation are based on the histological features as seen on light microscopy. The ultramicroscopic features associated with these conditions that may give more insight to the etiopathogenesis are unknown. Aim To study the ultrastructural changes occurring in mammary duct cones in patients with DE and PDM using Transmission Electron Microscopic (TEM). Method Major ducts removed by radical duct excision from 21 patients with final histopathological diagnosis of DE and PDM were subjected to TEM study with 2 normal duct samples as controls. Results The TEM features of DE were denudation of the epithelial cells with focal loss of microvilli, widening of the inter-epithelial junctions with focal disruption of the T bars, periductal collagenisation without inflammation, and features suggestive of Epithelial Mesenchymal Transition (EMT). PDM features are intact epithelial lining with proliferative epithelium and periductal collagenisation with inflammation. Conclusions Based on the TEM findings, we suggest that DE and PDM are two different entities. EMT a novel finding observed in DE in this study. PMID:28273122

Dissolution rates of subsoil limestone in a doline on the Akiyoshi-dai Plateau, Japan: An approach from a weathering experiment, hydrological observations, and electrical resistivity tomography

NASA Astrophysics Data System (ADS)

Akiyama, Sanae; Hattanji, Tsuyoshi; Matsushi, Yuki; Matsukura, Yukinori

2015-10-01

This study aims at estimating the controlling factors for the denudation rates of limestone, which often forms solution dolines on karst tablelands. Our approaches include (1) electrical resistivity tomography (ERT) to reveal shallow subsurface structures and hydrological settings, (2) automated monitoring of volumetric water content in soil profiles and manual measurements of subsurface CO2 concentrations and soil water chemistry, and (3) a field weathering experiment using limestone tablets with the micro-weight loss technique for determining current denudation rates. The field experiment and monitoring were carried out over 768 days from 2009-2011 at four sites with varying topographic and hydrological conditions along the sideslope of a doline on the Akiyoshi-dai karst plateau in SW-Japan. The installation depths of the limestone tablets were 15 cm or 50 cm below the slope surface. The soil moisture conditions varied site by site. Water-saturated conditions continued for 40-50% of the whole experimental period at 50-cm depth of upper and middle sites, while only 0-10% of the experimental period was water-saturated at the other sites. Chemical analysis revealed that the soil water was chemically unsaturated with calcite for all the sites. Spatial differences in concentrations of CO2 in soil pore air were statistically less significant. The denudation rates of the buried limestone tablets were 17.7-21.9 mg cm- 2 a- 1 at the upper and middle slopes, where the soil was water-saturated for a long time after precipitation. The lowest denudation of 3.9 mg cm- 2 a- 1 was observed on lower slopes where soil was not capable of maintaining water at a near saturation level even after precipitation. Statistical analysis revealed that the denudation rates of the tablets were strongly controlled by the duration for which soil pores were saturated by water (the conditions defined here are degrees of water saturation greater than 97%). Electrical resistivity tomography indicated that areas with high soil moisture conditions were located at the deeper zone on the lower slopes and the bottom of the doline, where denudation would be faster.

A multidisciplinary analysis to constrain exhumation and recent erosion history of the Tethyan Himalaya, based on apatite (U-Th-Sm)/He and cosmogenic nuclides dates from Central Nepal (Takkhola graben and the Mustang granite)

NASA Astrophysics Data System (ADS)

Rosenkranz, Ruben; Sahragard Sohi, Mohammad; Spiegel, Cornelia

2015-04-01

The exhumation of the Himalayan arc has been studied intensively throughout the last decades. For the Tethyan Himalaya, however, the youngest exhumation history is still unclear, mostly because of the lack of a significant apatite content in most Tethyan sediments (Crouzet et al. 2007). For this study we are using apatite (U-Th-Sm)/He thermochronology and cosmogenic nuclides for investigating exhumation and denudation of the Tethyan Himalaya back through time. Apatite (U-Th-Sm)/He thermochronology is sensitive to temperatures of ~40 to 85°C and thus to movements within the upper ~1.5 to 3 km of the earth's crust. During a recent field campaign, we sampled the Mustang granite, that intrudes the Tethyan marine sediments and the Takkhola-Graben. The graben can be seen as an inusual southern part of the normal faulting system affecting the whole Tibetan Plateau (Colchen, 1999). The timing of the activation of these faulting is still highly debated. The syntectonics filling of the Takkhola-Mustag graben consists of Mio-Pliocene fluvio-lacustrine deposits (Garzione et al. 2003). These were described as containing significant amounts of apatite, derived from the past erosion of the Mustang granitic body (Adhikari and Wagreich, 2011). Being only up to 1km thick, a post depositional thermal resetting of the apatite (U-Th-Sm)/He system is unlikely, so that the (U-Th-Sm)/He dates of the sediments are expected to have retained their information regarding source area exhumation. We took several sand samples from the Kali Gandaki River draining the present-day exposure of the Mustang granite. Furthermore, we sampled different stratigraphic levels of the Mio-Pliocene sedimentary rocks, i.e., from the Tetang and Takkahola formation deposited between 11 and 7 Ma. This sampling approach will not only provide information about the youngest denudation history of the Mustang granite /Tethyan Himalaya, but will also reveal insights into its past denudation and changes of denudation rates through time for the region north to the South Tibetan Detachment. It is our expectation to link the results to the tectonic behavior of the South Tibetan Detachment or to the newly recognized Western Nepal Fault System. Corroborating our results with other ages and diverse methods will provide a robust constraint on the exhumation and erosion history of the Tethyan Himalaya, as well as insights on the U-Th/He dating technique. References Adhikari, B.R. and Wagreich, M., 2011. Provenance evolution of collapse graben fill in the Himalaya-The Miocene to Quaternary Thakkhola-Mustang graben (Nepal). Sedimentary Geology, 233(1), pp.1-14. Blythe, A.E., Burbank, D.W., Carter, A., Schmidt, K., Putkonen, J., 2007. Plio-Quaternary exhumation history of the central Nepalese Himalaya: 1. Apatite and zircon fission track and apatite [U-Th]/He analyses. Tectonics, 26(3). Crouzet, C. et al., 2007. Temperature and age constraints on the metamorphism of the Tethyan Himalaya in Central Nepal: A multidisciplinary approach. Journal of Asian Earth Sciences, 30(1), pp.113-130. Garzione, C.N, DeCelles, P.G., Hokinson, D.G., Ojha, T.P., Upreti, B.N., 2003. East-west extension and Miocene environmental change in the southern Tibetan plateau: Thakkhola graben, central Nepal. Geological Society of America Bulletin, 115(1), pp.3-20. Colchen, M., 1999. The Takkhola-Mustang graben in Nepal and the latee Cenozoic extension in the Higher Himalayas. Journal of Asian Earth Sciences, 17, pp. 683-702.

Tertiary uplift of the Mt. Doonerak antiform, central Brooks Range, Alaska: Apatite fission track evidence from the Trans-Alaska Crustal Transect

USGS Publications Warehouse

O'Sullivan, P. B.; Moore, Thomas E.; Murphy, J.M.; Oldow, J.S.; Ave Lallemant, H.G.

1998-01-01

The Mt. Doonerak antiform is a northeast-trending, doubly plunging antiform located along the axial part of the central Brooks Range. This antiform is a crustal-scale duplex estimated to have a vertical displacement of ~15 km. The antiform folds the Amawk thrust, which separates relatively less displaced lower plate rocks in a window in the core of the antiform from allochthonous upper plate rocks of the Endicott Mountains allochthon. Because regional geological relations indicate that displacement on the Amawk thrust occurred between early Neocomian and early Albian time, uplift of the antiform is post-early Neocomian in age.Zircon fission-track data from the Mt. Doonerak antiform suggest -8-12 km of vertical denudation has occurred within the antiform region since -70-65 Ma. whereas apatite fission-track data indicate the antiform has experienced a minimum of -46 km of denudation since late Oligocene time. Following rapid denudation at -24 + 3 Ma, the rocks have experienced continued denudation to present surface conditions at a slower rate.We conclude from the relative relations and timing that the Mt. Doonerak duplex was constructed in part during the late Oligocene by reactivation of an older duplex formed during the latest Cretaceous to Paleocene. Deformation and uplift of Oligocene age for the axial part of the Brooks Range orogen is anomalously young, but it is the same age as the youngest episode of north-vergent contractional uplift in the northeastern Brooks Range. Because the Mt. Doonerak antiform displays structural characteristics similar to those of antiforms in the northeastern Brooks Range and because both regions experienced simultaneous rapid denudation, we suggest that the Mt. Doonerak antiform formed in response to an episode of contractional deformation that affected both areas in the late Oligocene.

Effects of topical budesonide on epithelial restitution in vivo in guinea pig trachea.

PubMed Central

Erjefält, J. S.; Erjefält, I.; Sundler, F.; Persson, C. G.

1995-01-01

BACKGROUND--Continuous epithelial shedding and restitution processes may characterise the airways in diseases such as asthma. Epithelial restitution involves several humoral and cellular mechanisms that may potentially be affected by inhaled anti-asthma drugs. The present study examines the effect of a topical steroid on epithelial restitution in vivo in the guinea pig. METHODS--The airway epithelium was mechanically removed from well defined areas of guinea pig trachea without surgery and without damage to the basement membrane or bleeding. An anti-inflammatory dose of budesonide (1 mg) was administered repeatedly to the tracheal surface by local superfusion 24 hours before, at (0 hours), and 24 hours after the denudation. Migration of epithelial cells, formation of a plasma exudation-derived gel, and appearance of luminal leucocytes were recorded by scanning electron microscopy. Cell proliferation was visualised by bromodeoxyuridine immunohistochemistry and tissue neutrophils and eosinophils by enzyme histochemistry. RESULTS--Immediately after creation of the denuded zone ciliated and secretory cells on its border dedifferentiated, flattened out, and migrated speedily (mean (SE) 2.3 (0.3) micron/min) over the basement membrane. After 48 hours the entire denuded zone (800 microns wide) was covered by a tightly sealed epithelium; at this time increased proliferation was observed in new and old epithelium and subepithelial cells. Budesonide had no detectable effect on epithelial dedifferentiation, migration, sealing, or proliferation. Immediately after denudation and continuously during the migration phase plasma was extravasated creating a fibrinous gel rich in leucocytes, particularly neutrophils, over the denuded area. Budesonide had no effect on either the gel or the leucocyte density. CONCLUSIONS--These observations suggest that topical glucocorticoids may not interfere with a fast and efficient restitution of the epithelium in the airways. Images PMID:7570417

Detrital Thermochronology Record of the Local-to-Extraregional Provenance Shift Recorded by the Northern Peninsular Ranges Forearc

NASA Astrophysics Data System (ADS)

Flores, M.; Shulaker, D. Z.

2016-12-01

Previously measured detrital zircon U-Pb age distributions have revealed that Late Cretaceous to Eocene forearc strata in the Santa Ana mountains region experienced a dramatic shift in sedimentary provenance from a 125-90 Ma northern Peninsular Ranges batholith (PRB) source region along the continental margin to a cratonal source area intruded by Late Cretaceous (85-75 Ma) plutons within the continental interior (western Sonora). To improve our understanding of the timing and magnitude of denudation prior to, and during this local to extraregional provenance shift, we have measured new detrital K-feldspar 40Ar/39Ar total fusion and zircon U-Pb age distributions from forearc sandstones. Our combined crystallization age and thermal history results confirm two pulses of rapid denudation of the PRB. These include a syn-batholith phase (Cenomanian) and a post-batholithic (Maastrichtian to Paleocene) phase attributed to shallow subduction. The new data require that significant (5-10 km) syn-batholithic erosional denudation of the northern PRB had already occurred by ca. 95 Ma and that post-emplacement denudation of the PRB accelerated again during the Maastrichtian with the eastern PRB providing the bulk of the detritus. Our new results demonstrate that deposition of the Paleocene Silverado Fm. occurred during a transitional period. Sand reaching the forearc during the Paleocene was derived from both the heavily denuded eastern PRB with additional input supplied either from Late Cretaceous plutons of northwestern Sonoran region and/or similar plutons emplaced in thrust sheets atop PRB basement within the Santa Rosa Mountains. In contrast, the Eocene Santiago Fm. was nearly entirely derived from extraregional sources that supplied abundant late Cretaceous (75-85 Ma) and Proterozoic (1.4 & 1.7 Ga) detritus with virtually no PRB-derived sediment detected.

Impaired M3 and enhanced M2 muscarinic receptor contractile function in a streptozotocin model of mouse diabetic urinary bladder

PubMed Central

Pak, K. J.; Ostrom, R. S.; Matsui, M.

2010-01-01

We investigated the contractile roles of M2 and M3 muscarinic receptors in urinary bladder from streptozotocin-treated mice. Wild-type and M2 muscarinic receptor knockout (M2 KO) mice were given a single injection of vehicle or streptozotocin (125 mg kg−1) 2–24 weeks prior to bladder assays. The effect of forskolin on contractions elicited to the muscarinic agonist, oxotremorine-M, was measured in isolated urinary bladder (intact or denuded of urothelium). Denuded urinary bladder from vehicle-treated wild-type and M2 KO mice exhibited similar contractile responses to oxotremorine-M, when contraction was normalized relative to that elicited by KCl (50 mM). Eight to 9 weeks after streptozotocin treatment, the EC50 value of oxotremorine-M increased 3.1-fold in urinary bladder from the M2 KO mouse (N = 5) compared to wild type (N = 6; P < 0.001). Analogous changes were observed in intact bladder. In denuded urinary bladder from vehicle-treated mice, forskolin (5 µM) caused a much greater inhibition of contraction in M2 KO bladder compared to wild type. Following streptozotocin treatment, this forskolin effect increased 1.6-fold (P = 0.032). At the 20- to 24-week time point, the forskolin effect increased 1.7-fold for denuded as well as intact bladders (P = 0.036, 0.01, respectively). Although streptozotocin treatment inhibits M3 receptor-mediated contraction in denuded urinary bladder, muscarinic contractile function is maintained in wild-type bladder by enhanced M2 contractile function. M2 receptor activation opposes forskolin-induced relaxation of the urinary bladder, and this M2 function is enhanced following streptozotocin treatment. PMID:20349044

Impaired M3 and enhanced M2 muscarinic receptor contractile function in a streptozotocin model of mouse diabetic urinary bladder.

PubMed

Pak, K J; Ostrom, R S; Matsui, M; Ehlert, F J

2010-05-01

We investigated the contractile roles of M2 and M3 muscarinic receptors in urinary bladder from streptozotocin-treated mice. Wild-type and M2 muscarinic receptor knockout (M2 KO) mice were given a single injection of vehicle or streptozotocin (125 mg kg(-1)) 2-24 weeks prior to bladder assays. The effect of forskolin on contractions elicited to the muscarinic agonist, oxotremorine-M, was measured in isolated urinary bladder (intact or denuded of urothelium). Denuded urinary bladder from vehicle-treated wild-type and M2 KO mice exhibited similar contractile responses to oxotremorine-M, when contraction was normalized relative to that elicited by KCl (50 mM). Eight to 9 weeks after streptozotocin treatment, the EC(50) value of oxotremorine-M increased 3.1-fold in urinary bladder from the M2 KO mouse (N = 5) compared to wild type (N = 6; P < 0.001). Analogous changes were observed in intact bladder. In denuded urinary bladder from vehicle-treated mice, forskolin (5 microM) caused a much greater inhibition of contraction in M2 KO bladder compared to wild type. Following streptozotocin treatment, this forskolin effect increased 1.6-fold (P = 0.032). At the 20- to 24-week time point, the forskolin effect increased 1.7-fold for denuded as well as intact bladders (P = 0.036, 0.01, respectively). Although streptozotocin treatment inhibits M3 receptor-mediated contraction in denuded urinary bladder, muscarinic contractile function is maintained in wild-type bladder by enhanced M2 contractile function. M2 receptor activation opposes forskolin-induced relaxation of the urinary bladder, and this M(2) function is enhanced following streptozotocin treatment.

Relaxant effect of ghrelin on guinea pig isolated tracheal smooth muscle: role of epithelial NO and PGE2.

PubMed

Al-Ayed, Mohammed Saeed Zayed

2018-06-01

This study aimed at investigating the potential ghrelin relaxing effect on guinea pig isolated tracheal smooth muscle (TSM). Using an in vitro experimental approach, the physiological role of the airway epithelium on smooth muscle relaxation has been investigated by analyzing the dose-response curves for carbachol- or histamine-induced contractions on epithelium intact versus denuded tracheal tissue. The relaxant effect of ghrelin (5-200 μmol/L) then investigated on carbachol-contracted, non-sensitized, and ovalbumin (OVA)-sensitized guinea pig TSM with an intact or denuded epithelium. The isolated TSMs from identical guinea pigs were incubated in Krebs solution aerated with 95% O 2 and 5% CO 2 through an automated tissue organ bath system (n = 6 for each group). The ghrelin relaxation mechanism was assessed by adding L-NAME, indomethacin, and YIL-781 for GHS-R1 into the tissue chamber. The spasmogens carbachol and histamine have shown a significantly higher contracting effect on epithelium-denuded than in epithelium-intact TSM confirmed by the significantly higher mean pEC50 of both agonists on the epithelium-denuded trachea (p < 0.05). Ghrelin has shown a concentration-dependent relaxing effect on carbachol-contracted TSM (r = 0.96, p = 0.00). The effect was more evident in the intact non-sensitized than in epithelium-denuded or OVA-sensitized groups (p < 0.05). Preincubation with nitric oxide (NO) and prostaglandin E 2 (PGE 2 ) inhibitors has significantly reduced the ghrelin-induced relaxation on epithelium-intact TSM suggesting an epithelium-dependant mechanism. However, GHS-R1a antagonist has also succeeded to reduce ghrelin relaxant effect, which needs further clarification. Ghrelin proved to have a potential TSM relaxant effect possibly through epithelium-dependant mechanisms involving NO and PGE 2 .

Mechanism of action vasodilation Annona muricata L. leaves extract mediated vascular smooth muscles

NASA Astrophysics Data System (ADS)

Ismail, S.; Hayati, N.; Rahmawati, N.

2018-04-01

Annona muricata L. leaves (AML) is used as ethnomedicine by the Dayak Abai ethnicity in North Kalimantan for its already known use to reduce blood pressure. However, the mechanism of action in the vessel is still poorly understood. Aim study to prove the mechanism of action of AML in blood vessels. AML was extracted with a maceration technique using ethanol solvent. Mechanism of action test was performed with isolated rat aortic with endothelium (endo-intact) and without endothelium (endo-denuded). AML extract intervention on rats aorta with endo-intact and endo-denuded can induction vasodilatation activity. Increasing AML extract concentration can improve decrease vasodilatation activity on isolated rats aortic with endo-intact compared to endo-denuded, it means that endothelium can weaken vasodilatation activity of aorta mediated by vascular smooth muscle after the extract was given.

Climate-driven unsteady denudation and sediment flux in a high-relief unglaciated catchment-fan using 26Al and 10Be: Panamint Valley, California

NASA Astrophysics Data System (ADS)

Mason, Cody C.; Romans, Brian W.

2018-06-01

Environmental changes within erosional catchments of sediment routing systems are predicted to modulate sediment transfer dynamics. However, empirical and numerical models that predict such phenomena are difficult to test in natural systems over multi-millennial timescales. Tectonic boundary conditions and climate history in the Panamint Range, California, are relatively well-constrained by existing low-temperature thermochronology and regional multi-proxy paleoclimate studies, respectively. Catchment-fan systems present there minimize sediment storage and recycling, offering an excellent natural laboratory to test models of climate-sedimentary dynamics. We used stratigraphic characterization and cosmogenic radionuclides (CRNs; 26Al and 10Be) in the Pleasant Canyon complex (PCC), a linked catchment-fan system, to examine the effects of Pleistocene high-magnitude, high-frequency climate change on CRN-derived denudation rates and sediment flux in a high-relief, unglaciated catchment-fan system. Calculated 26Al/10Be burial ages from 13 samples collected in an ∼180 m thick outcropping stratigraphic succession range from ca. 1.55 ± 0.22 Ma in basal strata, to ca. 0.36 ± 0.18-0.52 ± 0.20 Ma within the uppermost part of the succession. The mean long-term CRN-derived paleodenudation rate, 36 ± 8 mm/kyr (1σ), is higher than the modern rate of 24 ± 0.6 mm/kyr from Pleasant Canyon, and paleodenudation rates during the middle Pleistocene display some high-frequency variability in the high end (up to 54 ± 10 mm/kyr). The highest CRN-derived denudation rates are associated with stratigraphic evidence for increased precipitation during glacial-pluvial events after the middle Pleistocene transition (post ca. 0.75 Ma), suggesting 100 kyr Milankovitch periodicity could drive the observed variability. We investigated the potential for non-equilibrium sedimentary processes, i.e. increased landslides or sediment storage/recycling, to influence apparent paleodenudation rates; end-member mixing models suggest that a mixture of >50% low-CRN-concentration sediment from landslides is required to produce the largest observed increase in paleodenudation rate. The overall pattern of CRN-derived burial ages, paleodenudation rates, and stratigraphic facies suggests Milankovitch timescale climate transitions drive variability in catchment denudation rates and sediment flux, or alternatively that climate transitions affect sedimentary process regimes that result in measurable variability of CRN concentrations in unglaciated catchment-fan systems.

Baring high-albedo soils by overgrazing: a hypothesized desertification mechanism.

PubMed

Otterman, J

1974-11-08

Observations are reported of high-albedo soils denuded by overgrazing which appear bright, in high contrast to regions covered by natural vegetation. Measurements and modeling show that the denuded surfaces are cooler, when compared under sunlit conditions. This observed "thermal depression" eflect should, on theoretical grounds, result in a decreased lifting of air necessary for cloud formation and precipitation, and thus lead to regional climatic desertification.

Baring high-albedo soils by overgrazing - A hypothesized desertification mechanism

NASA Technical Reports Server (NTRS)

Otterman, J.

1974-01-01

Observations are reported of high-albedo soils denuded by overgrazing which appear bright, in high contrast to regions covered by natural vegetation. Measurements and modeling show that the denuded surfaces are cooler, when compared under sunlit conditions. This observed 'thermal depression' effect should, on theoretical grounds, result in a decreased lifting of air necessary for cloud formation and precipitation, and thus lead to regional climatic desertification.

Ecosystem Composition Controls the Fate of Rare Earth Elements during Incipient Soil Genesis

NASA Astrophysics Data System (ADS)

Zaharescu, Dragos G.; Burghelea, Carmen I.; Dontsova, Katerina; Presler, Jennifer K.; Maier, Raina M.; Huxman, Travis; Domanik, Kenneth J.; Hunt, Edward A.; Amistadi, Mary K.; Gaddis, Emily E.; Palacios-Menendez, Maria A.; Vaquera-Ibarra, Maria O.; Chorover, Jon

2017-02-01

The rare earth elements (REE) are increasingly important in a variety of science and economic fields, including (bio)geosciences, paleoecology, astrobiology, and mining. However, REE distribution in early rock-microbe-plant systems has remained elusive. We tested the hypothesis that REE mass-partitioning during incipient weathering of basalt, rhyolite, granite and schist depends on the activity of microbes, vascular plants (Buffalo grass), and arbuscular mycorrhiza. Pore-water element abundances revealed a rapid transition from abiotic to biotic signatures of weathering, the latter associated with smaller aqueous loss and larger plant uptake. Abiotic dissolution was 39% of total denudation in plant-microbes-mycorrhiza treatment. Microbes incremented denudation, particularly in rhyolite, and this resulted in decreased bioavailable solid pools in this rock. Total mobilization (aqueous + uptake) was ten times greater in planted compared to abiotic treatments, REE masses in plant generally exceeding those in water. Larger plants increased bioavailable solid pools, consistent with enhanced soil genesis. Mycorrhiza generally had a positive effect on total mobilization. The main mechanism behind incipient REE weathering was carbonation enhanced by biotic respiration, the denudation patterns being largely dictated by mineralogy. A consistent biotic signature was observed in La:phosphate and mobilization: solid pool ratios, and in the pattern of denudation and uptake.

Changing patterns of exhumation and denudation in front of an advancing crustal indenter, Tauern Window (Eastern Alps)

NASA Astrophysics Data System (ADS)

Favaro, S.; Handy, M. R.; Scharf, A.; Schuster, R.

2017-06-01

The changing shape of indenting crustal blocks during northward motion of the Adriatic microplate induced migration of Miocene doming and orogen-parallel extension of orogenic crust in the Tauern Window. New structural and kinematic data indicate that initial shortening of the Penninic nappe pile in the Tauern Window by upright folding and strike-slip faulting was transitional to coeval north-south shortening and east-west extension; the latter was accommodated by normal faulting at the eastern and western margins of the window. Retrodeforming these post-nappe structures in map view yields a map-view reconstruction of the orogenic crust back to 30 Ma, including the onset of pronounced indentation at 21 Ma. This model supports the notion that indentation involved approximately equal amounts of north-south shortening and orogen-parallel stretching and extrusion toward the Pannonian Basin, as measured from the indenter tip to the European foreland in the north and Austroalpine units in the east. Comparison of areal denudation of the orogenic crust before and after indentation indicates that erosion associated with upright folding was the primary agent of denudation, whereas extensional unroofing and limited erosion along normal faults at the eastern and western ends of the Tauern Window accounted for only about a third of the total denudation.

Ecosystem Composition Controls the Fate of Rare Earth Elements during Incipient Soil Genesis

PubMed Central

Zaharescu, Dragos G.; Burghelea, Carmen I.; Dontsova, Katerina; Presler, Jennifer K.; Maier, Raina M.; Huxman, Travis; Domanik, Kenneth J.; Hunt, Edward A.; Amistadi, Mary K.; Gaddis, Emily E.; Palacios-Menendez, Maria A.; Vaquera-Ibarra, Maria O.; Chorover, Jon

2017-01-01

The rare earth elements (REE) are increasingly important in a variety of science and economic fields, including (bio)geosciences, paleoecology, astrobiology, and mining. However, REE distribution in early rock-microbe-plant systems has remained elusive. We tested the hypothesis that REE mass-partitioning during incipient weathering of basalt, rhyolite, granite and schist depends on the activity of microbes, vascular plants (Buffalo grass), and arbuscular mycorrhiza. Pore-water element abundances revealed a rapid transition from abiotic to biotic signatures of weathering, the latter associated with smaller aqueous loss and larger plant uptake. Abiotic dissolution was 39% of total denudation in plant-microbes-mycorrhiza treatment. Microbes incremented denudation, particularly in rhyolite, and this resulted in decreased bioavailable solid pools in this rock. Total mobilization (aqueous + uptake) was ten times greater in planted compared to abiotic treatments, REE masses in plant generally exceeding those in water. Larger plants increased bioavailable solid pools, consistent with enhanced soil genesis. Mycorrhiza generally had a positive effect on total mobilization. The main mechanism behind incipient REE weathering was carbonation enhanced by biotic respiration, the denudation patterns being largely dictated by mineralogy. A consistent biotic signature was observed in La:phosphate and mobilization: solid pool ratios, and in the pattern of denudation and uptake. PMID:28230202

Paragenesis of thermal denudation with gas-emission crater and lake formation, Yamal Peninsula, Russia

NASA Astrophysics Data System (ADS)

Babkina, Elena; Khomutov, Artem; Leibman, Marina; Dvornikov, Yury; Kizyakov, Alexander; Babkin, Evgeny

2017-04-01

Gas-emission craters (GECs) found in the North of West Siberia in 2014 occur in an area of wide tabular ground ice (TGI) distribution. TGI observed in the GEC walls also provokes thermal denudation: a complex of processes responsible for formation of thermocirques (TCs). TCs are semi-circle shaped depressions resulting from TGI thaw and removal of detached material downslope. Shores of many lakes are terraced and have ancient to recent traces of thermal denudation activity. TCs are numerous in the GEC area giving reason to assume that GEC, TGI, TC, and lakes are interrelated. First found Yamal crater (GEC-1) expanded from initial 18 m wide deep hole in 2013 to an irregularly-shaped lake up to 85 meters wide in 2016. Expansion of the GEC was controlled by TGI thaw. This can be considered in terms of thermal denudation and analyzed on the basis of TC study in the adjacent area. In summer 2014 and 2015 (the lifetime of the GEC-1) its wall retreat covered the area of 1730 square meters, which gives 865 square meters per year. In 2016, which was the warmest for the period of observation at weather station Marre-Sale, retreat area increased to 2200 square meters per year. TC, which exposed TGI similar to that in the walls of GEC-1, is observed on the nearest lakeshore. TC activation probably started in 2012 as elsewhere on Yamal. In 2015 its area according to GPS survey reached 4400 square meters (a four-year average 1100 square meters). Since September 2015 and till October 2016 its area expanded by 2600 square meters, thus increased by 59%, and more than twice compared to previous annual average. Lake adjacent to GEC-1 in 2016 was separated from crater edge by only a 13 meter wide isthmus, most likely both GEC-1 lake and adjacent lake merge in few years. Therefore, single basis of erosion for thermal denudation appear. After lakes merge, it would become hard to determine what the initial process for the lake formation was if not for the occasional discovery of the GEC-1. Thus, the rate of thermal denudation measured as area expansion: (a) inside the GEC was between 865 square meters per year in 2014-2015, and 2200 square meters in 2016, (b) on the adjacent lakeshore thermal denudation expanded by 1100 square meters per year in 2012-2015 and was as high as 2600 square meters in 2016. In both landforms higher rates were observed in the warmest 2016 and were rather similar. Lower rate for the GEC-1 at its initial stage is due to it steep slopes and narrow hole with little sunshine reaching lower parts of the hole. Adjacent lake providing basis of erosion for both features expands towards the GEC-1 lake and outside into tundra by thermal denudation activity and determines formation of a new feature: merged lake with components having different origin. This research is supported by Russian Science Foundation Grant 16-17-10203.

Oxidation Microstructure Studies of Reinforced Carbon/Carbon

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.; Curry, Donald M.

2006-01-01

Laboratory oxidation studies of reinforced carbon/carbon (RCC) are discussed with particular emphasis on the resulting microstructures. This study involves laboratory furnace (500-1500 C deg) and arc-jet exposures (1538 C deg) on various forms of RCC. RCC without oxidation protection oxidized at 800 and 1100 C deg exhibits pointed and reduced diameter fibers, due to preferential attack along the fiber edges. RCC with a SiC conversion coating exhibits limited attack of the carbon substrate at 500, 700 and 1500 C deg. However samples oxidized at 900, 1100, and 1300 C deg show small oxidation cavities at the SiC/carbon interface below through-thickness cracks in the SiC coating. These cavities have rough edges with denuded fibers and can be easily distinguished from cavities created in processing. Arc-jet tests at 1538 C deg show limited oxidation attack when the SiC coating and glass sealants are intact. When the SiC/sealant protection system is damaged, attack is extensive and proceeds through matrix cracks, creating denuded fibers on the edges of the cracks. Even at 1538 C deg, where diffusion control dominates, attack is non-uniform with fiber edges oxidizing in preference to the bulk fiber and matrix.

Catchment-scale denudation and chemical erosion rates determined from 10Be and mass balance geochemistry (Mt. Lofty Ranges of South Australia)

NASA Astrophysics Data System (ADS)

Bestland, Erick A.; Liccioli, Caterina; Soloninka, Lesja; Chittleborough, David J.; Fink, David

2016-10-01

Global biogeochemical cycles have, as a central component, estimates of physical and chemical erosion rates. These erosion rates are becoming better quantified by the development of a global database of cosmogenic radionuclide 10Be (CRN) analyses of soil, sediment, and outcrops. Here we report the denudation rates for two small catchments (~ 0.9 km2) in the Mt. Lofty Ranges of South Australia as determined from 10Be concentrations from quartz sand from the following landscape elements: 1) dissected plateaux, or summit surfaces (14.10 ± 1.61 t km- 2 y- 1), 2) sandstone outcrops (15.37 ± 1.32 t km- 2 y- 1), 3) zero-order drainages (27.70 ± 1.42 t km- 2 y- 1), and 4) stream sediment which reflect a mix of landscape elements (19.80 ± 1.01 t km- 2 y- 1). Thus, the more slowly eroding plateaux and ridges, when juxtaposed with the more rapidly eroding side-slopes, are leading to increased relief in this landscape. Chemical erosion rates for this landscape are determined by combining cosmogenic denudation rates with the geochemical mass balance of parent rock, soil and saprolite utilizing zirconium immobility and existing mass balance methods. Two different methods were used to correct for chemical weathering and erosion in the saprolite zone that is shielded at depth from CRN production. The corrected values are higher than uncorrected values: total denudation of 33.24 or 29.11 t km- 2 y- 1, and total chemical erosion of 15.64 or 13.68 t km- 2 y- 1. Thus, according to these methods, 32-40% of the denudation is taking place by chemical weathering and erosion in the saprolite below CRN production depth. Compared with other similar areas, the overall denudation and chemical erosion rates are low. In most areas with sub-humid climates and tectonic uplift, physical erosion is much greater than chemical erosion. The low physical erosion rates in these Mt. Lofty Range catchments, in what is a relatively active tectonic setting, are thought to be due to low rainfall intensity during the winter wet season, which inhibits physical erosion such as land-sliding and debris flows.

Endothelial remodelling and intracellular calcium machinery.

PubMed

Moccia, F; Tanzi, F; Munaron, L

2014-05-01

Rather being an inert barrier between vessel lumen and surrounding tissues, vascular endothelium plays a key role in the maintenance of cardiovascular homeostasis. The de-endothelialization of blood vessels is regarded as the early event that results in the onset of severe vascular disorders, including atherosclerosis, acute myocardial infarction, brain stroke, and aortic aneurysm. Restoration of the endothelial lining may be accomplished by the activation of neighbouring endothelial cells (ECs) freed by contact inhibition and by circulating endothelial progenitor cells (EPCs). Intracellular Ca(2+) signalling is essential to promote wound healing: however, the molecular underpinnings of the Ca(2+) response to injury are yet to be fully elucidated. Similarly, the components of the Ca(2+) toolkit that drive EPC incorporation into denuded vessels are far from being fully elucidated. The present review will survey the current knowledge on the role of Ca(2+) signalling in endothelial repair and in EPC activation. We propose that endothelial regeneration might be boosted by intraluminal release of specific Ca(2+) channel agonists or by gene transfer strategies aiming to enhance the expression of the most suitable Ca(2+) channels at the wound site. In this view, connexin (Cx) channels/hemichannels and store-operated Ca(2+) entry (SOCE) stand amid the most proper routes to therapeutically induce the regrowth of denuded vessels. Cx stimulation might trigger the proliferative and migratory behaviour of ECs facing the lesion site, whereas activation of SOCE is likely to favour EPC homing to the wounded vessel.

Modes, tempo and spatial variability of Cenozoic cratonic denudation: morphoclimatic constraints from West Africa

NASA Astrophysics Data System (ADS)

Beauvais, Anicet; Chardon, Dominique

2010-05-01

After the onset of Gondwana break-up in the Early Mesozoic, the emerged part of the African plate underwent long Greenhouse effect climatic periods and epeirogeny. The last Greenhouse effect period in the Early Cenozoic and the alternation of wet and dry climatic periods since the Eocene enhanced episodes of rock chemical weathering and laterite production, forming bauxites and ferricretes, interrupted by drier periods of dominantly mechanical denudation, shaping glacis [1]. In Sub-Saharan West Africa, this evolution resulted in pulsate and essentially climatically-forced denudation that has shaped an ubiquitous sequence of five stepped lateritic paleosurfaces that synchronously developed over Cenozoic times. The modes, timing and spatial variability of continental denudation of the region are investigated by combining geomorphologic and geochronological data sets. The geomorphologic data set comprises the altitudinal distribution of the lateritic paleosurfaces relicts and their differential elevation from 42 locations in Sub-Saharan West Africa where the sequence (or part of it) has been documented. The geochronological data set consists in the age ranges of each paleosurface tackled by radiometric 39Ar-40Ar dating of the neoformed oxy-hydroxides (i.e., cryptomelane, K1-2Mn8O16, nH2O, [4]) carried by their laterites at the Tambao reference site, Burkina Faso [1, 3]. Five groups of 39Ar-40Ar ages, ~ 59 - 45 Ma, ~ 29 - 24 Ma, ~ 18 - 11.5 Ma, ~ 7.2 - 5.8 Ma, and ~ 3.4 - 2.9 Ma, characterize periods of chemical weathering whereas the time laps between these groups of ages correspond to episodes of mechanical denudation that reflect physical shaping of the paleosurfaces. For the last 45 Ma, the denudation rate estimates (3 to 8 m Ma-1) are comparable with those derived on shorter time scale (103 to 106 y.) in the same region by the cosmogenic radionuclide method [2]. Combined with the geomorphologic data set, these age ranges allow the visualization of the regional variability in the estimates of local relief and denudation rates for several time spans defined between selected paleosurfaces in the sequence. Denudation rates, ranging from ~ 4 m to ~ 25 m Ma-1, reflect overall acceleration of erosion rates in the Neogene. The observed space-time variability of the denudation rates suggest the interplay of (1) duration and intensity of climatically driven physical erosion periods, (2) absolute elevation and position of the considered sites with respect to the main continental divides, and (3) potential reorganization of the large-scale drainage. The results provide a new perspective for the detection, dating and quantification of subtle epeirogenic movements in West Africa, once combined with the sedimentary record of Cenozoic intracratonic and coastal basins. [1] Beauvais, A., Ruffet, G., Hénocque, O., Colin, F., 2008. Chemical and physical erosion rhythms of the West African Cenozoic morphogenesis: The 39Ar-40Ar dating of supergene K-Mn oxides. J. Geophys. Res. Earth Surface 113, F04007, doi :10.1029/2008JF000996. [2] Brown, E.T., Bourlès, D.L., Colin, F., Sanfo, Z., Raisbeck, G.M., Yiou, F., 1994. The development of iron crust lateritic systems in Burkina Faso, West Africa examined with in-situ-produced cosmogenic nuclides. Earth Planet. Sci. Letters 124, 19-33. [3] Colin, F., Beauvais, A., Ruffet, G., Hénocque, O., 2005. First 40Ar/39Ar geochronology of lateritic manganiferous pisolites: Implications for the palaeogene history of a West African landscape. Earth Planet. Sci. letters 238, 172-188. [4] Vasconcelos, P.M., 1999. K-Ar and 40Ar/39Ar geochronology of weathering processes. Ann. Rev. Earth Planet. Sci. 27, 183-229.

Microstructural Evolution of INCONEL® Alloy 740H® Fusion Welds During Creep

NASA Astrophysics Data System (ADS)

Bechetti, Daniel H.; DuPont, John N.; de Barbadillo, John J.; Baker, Brian A.; Watanabe, Masashi

2015-02-01

Electron microscopy techniques have been used to investigate the cause of premature creep failure in the fusion zone of INCONEL® Alloy 740H® (INCONEL and 740H are registered trademarks of Special Metals Corporation) welds. The reduced creep rupture lives of all-weld-metal and cross-weld creep specimens (relative to base metal specimens) have been attributed to the presence of large grain boundary regions that were denuded in fine γ' but contained coarse, elongated particles. Investigation of creep rupture specimens has revealed four factors that influence the formation of these coarsened zones, and the large particles found within them have been identified as γ'. Comparisons of the microstructural characteristics of these zones to the characteristics that are typical of denuded zones formed by a variety of mechanisms identified in the literature have been made. It is concluded that the mechanism of γ'-denuded zone formation in alloy 740H is discontinuous coarsening of the γ' phase. The discontinuous reaction is catalyzed by the grain boundary migration and sliding which occur during creep and likely promoted by the inhomogeneous weld metal microstructure that results from solute segregation during solidification. The increased susceptibility to the formation of the observed γ'-denuded zones in the weld metal as compared to the base metal is discussed in the context of differences in the contributions to the driving force for the discontinuous coarsening reaction.

Influence of co-culture with denuded oocytes during in vitro maturation on fertilization and developmental competence of cumulus-enclosed porcine oocytes in a defined system.

PubMed

Appeltant, Ruth; Somfai, Tamás; Kikuchi, Kazuhiro; Maes, Dominiek; Van Soom, Ann

2016-04-01

Co-culture of cumulus-oocyte complexes (COCs) with denuded oocytes (DOs) during in vitro maturation (IVM) was reported to improve the developmental competence of oocytes via oocyte-secreted factors in cattle. The aim of the present study was to investigate if addition of DOs during IVM can improve in vitro fertilization (IVF) and in vitro culture (IVC) results for oocytes in a defined in vitro production system in pigs. The maturation medium was porcine oocyte medium supplemented with gonadotropins, dbcAMP and β-mercaptoethanol. Cumulus-oocyte complexes were matured without DOs or with DOs in different ratios (9 COC, 9 COC+16 DO and 9 COC+36 DO). Consequently; oocytes were subjected to IVF as intact COCs or after denudation to examine if DO addition during IVM would affect cumulus or oocyte properties. After fertilization, penetration and normal fertilization rates of zygotes were not different between all tested groups irrespective of denudation before IVF. When zygotes were cultured for 6 days, no difference could be observed between all treatment groups in cleavage rate, blastocyst rate and cell number per blastocyst. In conclusion, irrespective of the ratio, co-culture with DOs during IVM did not improve fertilization parameters and embryo development of cumulus-enclosed porcine oocytes in a defined system. © 2015 Japanese Society of Animal Science.

The influence of cumulus cells during in vitro fertilization of buffalo (Bubalus bubalis) denuded oocytes that have undergone vitrification.

PubMed

Attanasio, Laura; De Rosa, Anna; De Blasi, Marina; Neglia, Gianluca; Zicarelli, Luigi; Campanile, Giuseppe; Gasparrini, Bianca

2010-11-01

The aim of this work was to evaluate whether providing a support of cumulus cells during IVF of buffalo denuded oocytes submitted to vitrification-warming enhances their fertilizing ability. In vitro matured denuded oocytes were vitrified by Cryotop in 20% EG + 20% of DMSO and 0.5 M sucrose and warmed into decreasing concentrations of sucrose (1.25 M-0.3M). Oocytes that survived vitrification were fertilized: 1) in the absence of a somatic support (DOs); 2) in the presence of bovine cumulus cells in suspension (DOs+susp); 3) on a bovine cumulus monolayer (DOs+monol); and 4) with intact bovine COCs in a 1:1 ratio (DOs+COCs). In vitro matured oocytes were fertilized and cultured to the blastocyst stage as a control. An increased cleavage rate was obtained from DOs+COCs (60.9%) compared to DOs, DOs+susp (43.6 and 38.4, respectively; P < 0.01) and DOs+monol (47.5%; P < 0.05). Interestingly, cleavage rate of DOs+COCs was similar to that of fresh control oocytes (67.8%). However, development to blastocysts significantly decreased in all vitrification groups compared to the control (P < 0.01). In conclusion the co-culture with intact COCs during IVF completely restores fertilizing capability of buffalo denuded vitrified oocytes, without improving blastocyst development. Copyright © 2010 Elsevier Inc. All rights reserved.

Halogen speciation in volcanic plumes - Development of compact denuder sampling techniques with in-situ derivatization followed by gas chromatography-mass spectrometry and their application at Mt. Etna, Mt. Nyiragongo and Mt. Nyamulagira in 2015.

NASA Astrophysics Data System (ADS)

Rüdiger, Julian; Bobrowski, Nicole; Hoffmann, Thorsten

2016-04-01

Volcanoes are a large source for several reactive atmospheric trace gases including sulfur and halogen containing species. The detailed knowledge of volcanic plume chemistry can give insights into subsurface processes and can be considered as a useful geochemical tool for monitoring of volcanic activity, especially halogen to sulfur ratios (e.g. Bobrowski and Giuffrida, 2012; Donovan et al., 2014). The reactive bromine species bromine monoxide (BrO) is of particular interest, because BrO as well as SO2 are readily measurable by UV spectrometer at a safe distance. Furthermore it is formed in the plume by a multiphase reaction mechanism under depletion of ozone in the plume. The abundance of BrO changes as a function of the reaction time and therefore distance from the vent as well as the spatial position in the plume. The precursor substance for the formation of BrO is HBr with Br2as an intermediate product. The reaction of HBr to BrO involves heterogeneous reactions involving aerosol particles, while Br2 reacts directly with O3 to form BrO in a UV radiation induced mechanism. Due to the lack of analytical approaches for the species analysis of halogens (HBr, Br2, Br, BrCl, HOBr) there are still uncertainties about the magnitude of volcanic halogen emissions and in particular their speciation and therefore also in the understanding of the bromine chemistry in volcanic plumes (Bobrowski et al., 2007). In this study a gas diffusion denuder sampling method using a 1,3,5-trimethoxybenzene (1,3,5-TMB) coating for the derivatization of reactive halogen species (Rüdiger et al., 2015) was characterized by reaction chamber experiments. The coating proved to be suitable to collect selectively gaseous bromine species with oxidation states of +1 or 0 (such as Br2, BrCl, BrO(H) and BrONO2), while being ignorant to HBr (OS -1). The reaction of 1,3,5-TMB with reactive bromine species gives 1-bromo-2,4,6-trimethoxybenzene (1-bromo-2,4,6-TMB) - other halogens give corresponding products. The diffusion denuder technique allows sampling of gaseous compounds exclusively without collecting particulate matter. Solvent elution of the derivatized analytes and subsequent analysis with gas chromatography-mass spectrometry gives a limit of detection below 1 ng of bromine. The method was applied in 2015 on volcanic gas plumes at Mt. Etna (Italy), Mt. Nyiragongo and Mt. Nyamulagira (DR Congo) giving reactive bromine mixing ratios from 0.3 ppb (Nyiragongo) up to 22 ppb (Etna, NEC). Compared with total halogen data derived by alkaline trap sampling (Raschig-tube) and ion-chromatography analysis the reactive bromine mixing ratios allow the investigation of the conversion of HBr into reactive species due to plume chemistry with progressing plume age. The new method will be described in detail and the first results on the reactive halogen to total halogen output will be discussed (for bromine and chlorine) and compared to earlier volcanic plume chemistry model studies. References Bobrowski, N. and G. Giuffrida: Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006-2009. Solid Earth, 3, 433-445, 2012 Bobrowski, N., R. von Glasow, A. Aiuppa, S. Inguaggiato, I. Louban, O. W. Ibrahim and U. Platt: Reactive halogen chemistry in volcanic plumes. J. Geophys. Res., 112, 2007 Donovan A., V. Tsanev, C. Oppenheimer and M. Edmonds: Reactive halogens (BrO and OClO) detected in the plume of Soufrière Hills Volcano during an eruption hiatus. Geochem. Geophys. Geosyst., 15, 3346-3363, 2014 Rüdiger, J., N. Bobrowski, T. Hoffmann (2015), Development and application of compact denuder sampling techniques with in situ derivatization followed by gas chromatography-mass spectrometry for halogen speciation in volcanic plumes (EGU2015-2392-2), EGU General Assembly 2015

Development and application of gas diffusion denuder sampling techniques with in situ derivatization for the determination of hydrogen halides in volcanic plumes

NASA Astrophysics Data System (ADS)

Gutmann, Alexandra; Rüdiger, Julian; Bobrowski, Nicole; Hoffmann, Thorsten

2017-04-01

Volcanoes emit large amounts of gases into the atmosphere. The gas composition in volcanic plumes vary, driven by subsurface processes (such as magma rising) as well as by chemical reactions within the plume after mixing with ambient air. The knowledge of the gas composition can be a useful tool to monitor volcanic activity changes. However, to use the plume composition as a monitoring parameter, it is essential to understand the chemical reactions inside volcanic plumes, in particular when interpretation of volcanic activity changes is based on reactive gas species, such as bromine monoxide or molecular halogens. Changes in BrO/SO2-ratios, measured by UV spectrometers, have already been interpreted in connection with increasing volcanic activity prior to eruptions. But the abundance of BrO changes as a function of the reaction time, and therefore with distance from the vent, as well as the spatial position in the plume. Actually model and field studies assume a non-direct emission of BrO, but its formation due to photochemical and multiphase reactions involving gas and particle phase of volcanic emission mixed with the surrounding atmosphere. However, same models presume HBr as initially emitted species. Therefore, HBr is an important species linking BrO to geophysical processes in volcanic systems. Due to the lack of analytical methods for the accurate speciation of certain halogens (HBr, Br2, Br, BrCl, HOBr, etc.) there are still large uncertainties about the magnitude of volcanic halogen emissions, and in the understanding of the bromine chemistry in volcanic plumes. Since the concentrations of hydrogen halides are not directly accesable by remote sensing techniques, an in situ method with coated gas diffusion denuder was developed. The method uses selective derivatization reaction of gaseous hydrogen halides with an organic compound for the enrichment and immobilization. For this task 5,6-Epoxy-5,6-dihydro-1,10-phenanthrolin was identified as a suitable derivatization agent. The reaction with HBr results in the formation of 5-Bromo-5,6-dihydro-6-hydroxy-1,10-phenanthrolin. Other hydrogen halides give corresponding products. Using a denuder based sampling system with in situ derivatization it is also possible to differentiate even between gaseous and particulate hydrogen bromine. The derivatized analytes were analyzed with high pressure liquid chromatography-mass spectrometry. We applied this approach to measure hydrogen halide mixing ratios (ppt to ppb range depending on plume age) in the plumes of different volcanoes: Stromboli, Italy; Masaya, Nicaragua; Turrialba, Costa Rica. The results of this measurements will be presented. Samples were taken at various distances to the emission source and have been compared with complementary data (e.g. SO2 from alkaline traps or gas sensors). Furthermore, the sampling method has been applied on an unmanned aerial vehicle for downwind sample collection.

Implications of drainage rearrangement for passive margin escarpment evolution in southern Brazil

NASA Astrophysics Data System (ADS)

de Sordi, Michael Vinicius; Salgado, André Augusto Rodrigues; Siame, Lionel; Bourlès, Didier; Paisani, Julio Cesar; Léanni, Laëtitia; Braucher, Régis; Do Couto, Edivando Vítor; Aster Team

2018-04-01

Although several authors have pointed out the importance of earth surface process to passive margin escarpments relief evolution and even drainage rearrangements, the dynamics of a consolidated capture area (after a drainage network erodes the escarpment, as the one from the Itajaí-Açu River) remain poorly understood. Here, results are presented from radar elevation and aerial imagery data coupled with in-situ-produced 10Be concentrations measured in sand-sized river-born sediments from the Serra Geral escarpment, southern Brazil. The Studied area's relief evolution is captained by the drainage network: while the Itajaí-Açu watershed relief is the most dissected and lowest in elevation, it is significantly less dissected in the intermediate elevation Iguaçu catchment, an important Paraná River tributary. These less dissected and topographically higher areas belong to the Uruguai River catchment. These differences are conditioned by (i) different lithology compositions, structures and genesis; (ii) different morphological configurations, notably slope, range, relief; and (iii) different regional base levels. Along the Serra Geral escarpment, drainage features such as elbows, underfitted valleys, river profile anomalies, and contrasts in mapped χ-values are evidence of the rearrangement process, mainly beheading, where ocean-facing tributaries of the Itajaí-Açu River capture the inland catchments (Iguaçu and Uruguai). The 10Be derived denudation rates reinforced such processes: while samples from the Caçador and Araucárias Plateaus yield weighted means of 3.1 ± 0.2 and 6.5 ± 0.4 m/Ma respectively, samples from along the escarpment yield a weighted mean of 46.8 ± 3.6 m/Ma, almost 8 times higher. Such significant denudation rate differences are explained by base-level control, relief characteristics, and the geology framework. The main regional morphological evolutionary mechanism is headward denudation and piracy by the Itajaí-Açu River tributaries. As the escarpment moves from east to west, Itajaí-Açu River tributaries develop, leading to regional relief lowering and area losses within the Iguaçu and Uruguai catchments. Such processes were accelerated since Itajaí-Açu tributaries reached into sedimentary and volcanic rocks. From this moment on, Serra Geral became the main hydrographic divide between the ocean- and inland facing-catchments in the area.

Coatings for directional eutectics

NASA Technical Reports Server (NTRS)

Rairden, J. R.; Jackson, M. R.

1976-01-01

Significant advances have been made in the development of an environmentally stable coating for a very high strength, directionally solidified eutectic alloy designated NiTaC-13. Three duplex (two-layer) coatings survived 3,000 hours on a cyclic oxidation test (1,100 C to 90 C). These coatings were fabricated by first depositing a layer of NiCrAl(Y) by vacuum evaporation from an electron beam heated source, followed by depositing an aluminizing overlayer. The alloy after exposure with these coatings was denuded of carbide fibers at the substrate/coating interface. It was demonstrated that TaC fiber denudation can be greatly retarded by applying a carbon-bearing coating. The coating was applied by thermal spraying followed by aluminization. Specimens coated with NiCrAlCY+Al survived over 2,000 hours in the cyclic oxidation test with essentially no TaC denudation. Coating ductility was studied for coated and heat-treated bars, and stress rupture life at 871 C and 1,100 C was determined for coated and cycled bars.

Current denudation rates in dolostone karst from central Spain: Implications for the formation of unroofed caves

NASA Astrophysics Data System (ADS)

Krklec, Kristina; Domínguez-Villar, David; Carrasco, Rosa M.; Pedraza, Javier

2016-07-01

Rock tablets of known weight were buried in the soil of a karst region in Central Spain to evaluate the carbonate weathering during a period of a year. The experiment was conducted at two different soil depths: 5-10 and 50-55 cm from the surface. The parental rock used in the experiment is composed of dolomite and magnesite with variable proportion of accessory minerals and minor elements. Soil mineral and chemical composition as well as its texture was also characterized. Meteorological conditions at the site together with temperature and CO2 in both soil levels were monitored. Sets of tablets were retrieved after 6 and 12 months of the start of the experiment to account for seasonal weathering. Different lithologies do not exhibit significant differences in weathering, although a large inter-sample variability is attributed to variable size and distribution of the porosity. Results show an enhanced weathering during the wet and cold season that accounts for 78 ± 1% of the total annual weathering. Rock tablets examined under scanning electron microscopy prior and after exposure to natural environment show that most of the material lost occurred along cracks, edges or large pores. Although dissolution is a common process, most of the weathering is due to crystal detachment. Rock tablets at the depth of 5-10 cm were weathered 68 ± 1% more than those set at 50-55 cm from the surface. Higher soil moisture and concentration of CO2 were found deeper in the soil, which likely enhanced the dissolution of carbonate. However, physical weathering dominated weight loss of rock tablets at both soil depths; especially at the 5-10 cm level where soil thermal and moisture cycles were more frequent and greater. Denudation rate calculated from the 12 months set provides values of 2.48 ± 1.07 μm/yr and 1.75 ± 0.66 μm/yr at the depths of 5-10 and 50-55 cm, respectively. Since the conditions at the average contact between soil and bedrock are similar to those at the 50-55 cm depth, we consider that this is a more reliable denudation rate for the studied location during the studied period. The calculated weathering rate suggests that denudation has a limited contribution to the thinning of bedrock over caves at this site. Therefore, we consider that the formation of unroofed caves in this region most likely results from the thinning of bedrock cover over caves due to collapse of blocks from their ceilings.

Black and Brown Carbon in Biogenic Settings with Different Levels of Anthropogenic Influence, and The Effect of Semivolatile Compounds on Aerosol Optical Properties

NASA Astrophysics Data System (ADS)

Tasoglou, A.; Ramachandran, S.; Khlystov, A.; Saha, P.; Grieshop, A. P.; Pandis, S. N.

2015-12-01

Secondary organic aerosol (SOA) is a major contributor to the global aerosol burden. Black carbon (BC) is a significant climate warming agent, while light-absorbing organic carbon (brown carbon, BrC), also impacts the atmospheric radiative balance. The optical properties of ambient aerosols can be affected by biogenic SOA through the lensing effect (coating of BC cores by semivolatile SOA), and by the potential formation of BrC from biogenic sources influenced by anthropogenic sources. To evaluate these effects, measurements of ambient aerosol optical properties and BC concentrations were made in rural Centreville, AL (a remote site with little anthropogenic influence) in summer 2013 and at Duke Forest in Chapel Hill, NC (a site close to high density vehicular traffic and industrial sources), during summer 2015. Photoacoustic extinctiometers (PAX, 405 nm and 532 nm) measured particulate light absorption and a single particle soot photometer (SP2) measured BC mass at both locations. A seven-wavelength Aethalometer and a three-wavelength nephelometer were also deployed at Duke Forest. A third PAX (870 nm) was deployed at Centreville. For absorption and BC measurements, the sample was cycled between a dry line and a dry/thermally-denuded line. Hourly samples were collected with a steam jet aerosol collector (SJAC) for online (2013) and offline (2015) chemical composition analysis. BC concentrations were generally higher at Duke Forest compared to the rural Centreville site. The Aethalometer readings at Duke Forest show greater absorption at the shorter wavelengths (370 nm and 470 nm) than expected from the absorption at 880 nm coupled with an inverse wavelength dependence, suggesting the presence of brown carbon. This presentation will examine the evidence for brown carbon at the two sites, as well as the effect of non-BC coatings on BC light absorption (the lensing effect.)

The Impact of Organo-Mineral Complexation on Mineral Weathering in the Soil Zone under Unsaturated Conditions

NASA Astrophysics Data System (ADS)

Michael, H. A.; Tan, F.; Yoo, K.; Imhoff, P. T.

2017-12-01

While organo-mineral complexes can protect organic matter (OM) from biodegradation, their impact on soil mineral weathering is not clear. Previous bench-scale experiments that focused on specific OM and minerals showed that the adsorption of OM to mineral surfaces accelerates the dissolution of some minerals. However, the impact of natural organo-mineral complexes on mineral dissolution under unsaturated conditions is not well known. In this study, soil samples prepared from an undisturbed forest site were used to determine mineral weathering rates under differing conditions of OM sorption to minerals. Two types of soil samples were generated: 1) soil with OM (C horizon soil from 84-100cm depth), and 2) soil without OM (the same soil as in 1) but with OM removed by heating to 350°for 24 h). Soil samples were column-packed and subjected to intermittent infiltration and drainage to mimic natural rainfall events. Each soil sample type was run in duplicate. The unsaturated condition was created by applying gas pressure to the column, and the unsaturated chemical weathering rates during each cycle were calculated from the effluent concentrations. During a single cycle, when applying the same gas pressure, soils with OM retained more moisture than OM-removed media, indicating increased water retention capacity under the impact of OM. This is consistent with the water retention data measured by evaporation experiments (HYPROP) and the dew point method (WP4C Potential Meter). Correspondingly, silicon (Si) denudation rates indicated that dissolution of silicate minerals was 2-4 times higher in OM soils, suggesting that organo-mineral complexes accelerate mineral dissolution under unsaturated conditions. When combining data from all cycles, the results showed that Si denudation rates were positively related to soil water content: denundation rate increased with increasing water content. Therefore, natural mineral chemical weathering under unsaturated conditions, while widely considered to be facilitated by biological and chemical activities, may also be affected by soil retention properties.

Deformation associated with the denudation of mantle-derived rocks at the Mid-Atlantic Ridge 13°-15°N: The role of magmatic injections and hydrothermal alteration

NASA Astrophysics Data System (ADS)

Picazo, Suzanne; Cannat, Mathilde; Delacour, AdéLie; EscartíN, Javier; RouméJon, StéPhane; Silantyev, Sergei

2012-09-01

Outcrops of deeply derived ultramafic rocks and gabbros are widespread along slow spreading ridges where they are exposed in the footwall of detachment faults. We report on the microstructural and petrological characteristics of a large number of samples from ultramafic exposures in the walls of the Mid-Atlantic Ridge (MAR) axial valley at three distinct locations at lat. 13°N and 14°45'N. One of these locations corresponds to the footwall beneath a corrugated paleo-fault surface. Bearing in mind that dredging and ROV sampling may not preserve the most fragile lithologies (fault gouges), this study allows us to document a sequence of deformation, and the magmatic and hydrothermal history recorded in the footwall within a few hundred meters of the axial detachment fault. At the three sampled locations, we find that tremolitic amphiboles have localized deformation in the ultramafic rocks prior to the onset of serpentinization. We interpret these tremolites as hydrothermal alteration products after evolved gabbroic rocks intruded into the peridotites. We also document two types of brittle deformation in the ultramafic rocks, which we infer could produce the sustained low magnitude seismicity recorded at ridge axis detachment faults. The first type of brittle deformation affects fresh peridotite and is associated with the injection of the evolved gabbroic melts, and the second type affects serpentinized peridotites and is associated with the injection of Si-rich hydrothermal fluids that promote talc crystallization, leading to strain localization in thin talc shear zones. We also observed chlorite + serpentine shear zones but did not identify samples with serpentine-only shear zones. Although the proportion of magmatic injections in the ultramafic rocks is variable, these characteristics are found at each investigated location and are therefore proposed as fundamental components of the deformation in the footwall of the detachment faults associated with denudation of mantle-derived rocks at the MAR.

Comment on “Observations of ammonia, nitric acid, and fine particles in a rural gas production region” by Yi Li, Florian M. Schwandnera, H. James Sewell, Angela Zivkovich, Mark Tigges, Suresh Raja, Stephen Holcomb, John V. Molenar, Lincoln Sherman, Cassie Archuleta, Taehyoung Lee and Jeffrey L. Collett Jr. Atmospheric Environment (in press)

NASA Astrophysics Data System (ADS)

Phillips, Gavin J.

2014-05-01

An artefact of the detection of nitric acid (HNO3) by denuder methods is discussed. This artefact arises from the likely reaction of dinitrogen pentoxide (N2O5) on the denuder train resulting in the report of some fraction of N2O5 as HNO3.

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Atwani, Osman; Nathaniel II, James E.; Leff, Asher C.

Nanocrystalline materials are radiation-tolerant materials’ candidates due to their high defect sink density. Here, nanocrystalline iron films were irradiated with 10 keV helium ions in situ in a transmission electron microscope at elevated temperatures. Grain-size-dependent bubble density changes and denuded zone occurrence were observed at 700 K, but not at 573 K. This transition, attributed to increased helium–vacancy migration at elevated temperatures, suggests that nanocrystalline microstructures are more resistant to swelling at 700 K due to decreased bubble density. Finally, denuded zone formation had no correlation with grain size and misorientation angle under the conditions studied.

Denudational surface processes and trends of relief development in mountain valleys in western Norway

NASA Astrophysics Data System (ADS)

Laute, Katja; Beylich, Achim A.

2014-05-01

The various rates at which mountain landscapes are changing today are a response to (i) the long-term landscape history, (ii) the contemporary imprint of current tectonic activity, (iii) climate variability and (iv) anthropogenic influences. Large areas of the Norwegian mountainous fjord landscapes are today occupied by hillslopes which reflect the influence of glacial inheritance from the Last Glacial Maximum (LGM) as a direct response to climate variability during the Pleistocene. This study deals with the quantitative analysis of denudational slope processes and relief development occurring in selected mountain valleys in western Norway from the end of the LGM until today. The main focus of this research is two-fold: (i) analyzing the complexity of hillslope development since the LGM in glacially formed valleys, and (ii) assessing the spatio-temporal variability, controls and rates of relevant denudational slope processes operating under Holocene to contemporary environmental conditions in western Norway. Five years of research (2009-2013) were conducted in two steep, parabolic-shaped and glacier-connected neighbouring drainage basins, Erdalen (79.5 km2) and Bødalen (60.1 km2), located on the western side of the Jostedalsbreen ice cap in western Norway. The process-based approach applied encompasses techniques and methods for geomorphic process analysis of past (e.g. DEM/GIS based spatial data analysis, geophysical investigation of slope storage) and contemporary (process monitoring in field, in-depth studies of relevant slope processes) denudational process activity. The main results of this work reveal that the Holocene to contemporary slope processes and the connected relief development during this time period are primarily controlled by the imprint of the glacial history of the study areas which can be seen as a direct response to climate variability. Apart from that, a significant influence of the Little Ice Age (LIA) glacier advance on hillslope morphometry was discovered, with the LIA glacier advance causing higher intensities of post-LIA denudation on hillslope systems affected by the LIA glacier advance as compared to non-affected hillslope systems. Distinct differences are found between single headwater systems of the Erdalen and Bødalen drainage basins (i) regarding the absolute and relative importance of different contemporary slope processes as well as (ii) with respect to the importance of sediment delivery from headwater systems for the sedimentary budgets of the entire drainage basin systems. The detected differences are seen as a direct consequence of the varying glacially inherited valley morphometries which determine hillslope storage capacity, the average process transport distances and the intensity of hillslope-channel coupling. A comparison to geomorphic process rates published for other cold climate environments situated at high latitudes of the northern hemisphere permits the statement that the general intensity of present-day denudational processes in Erdalen and Bødalen is in a comparable range of magnitude. Even though denudational slope processes are leading to an ongoing valley widening, the Holocene modification of the inherited glacial relief until today is regarded to be minor. The results from the two selected typical drainage basins are considered to be representative on a regional scale for the mountainous fjord landscape in western Norway.

Do cosmogenic nuclides (10Be, 14C , 21Ne, 26Al) track late Quaternary climate changes on the Altiplano?

NASA Astrophysics Data System (ADS)

Hippe, K.; Kober, F.; Zeilinger, G.; Ivy-Ochs, S.; Kubik, P.; Maden, C.; Wieler, R.

2010-12-01

The high Altiplano plateau is the most prominent element of the Central Andes, separating the Andean Cordilleras between 15° to 22° S. It represents a tectonically quiet, intramontane basin with arid to semi-arid climate, low relief and internal drainage. Throughout the late Quaternary regional climate on the Altiplano repeatedly changed between wet and dry conditions [1]. The influence of climate on the plateau evolution during the Pleistocene/Holocene is unclear, however, as data on erosion processes and rates on the Altiplano are sparse. Here, we present a multiple-nuclide study investigating surface denudation at the eastern Altiplano of Bolivia (16°-17° S) on millennial and longer timescales. The aim is a better understanding of the complex feedback between climate, tectonics and geomorphology on the topographic evolution of the Andes. Catchment-wide denudation (CWD) rates are provided for a 150 km NW-SE transect along the Altiplano edge based on the analyses of cosmogenic 10Be, 26Al, 21Ne and in-situ 14C in river-borne sediment. Single nuclide CWD rates obtained for 10Be, 26Al and 21Ne are similar for all three nuclides and on the order of 3-37 mm/ka. Thus, the calculated denudation rates provide an averaged denudation history dating back at least to the middle Pleistocene. Denudation rates correlate positively with the mean basin hillslope, which is mainly controlled by basin lithology. For most catchments both, the 26Al/10Be ratios and the 21Ne/10Be ratios indicate a complex erosion/exposure history with probably several periods of sediment storage and burial/shielding totalling ~0.5 - 1.2 Ma. Local geomorphology featuring low slopes and low relief, small terraces and local floodplains also suggests that sediment transport might have been periodically ineffective. Concentrations of in-situ produced short-lived 14C are significantly lower than expected from the concentrations of the long-lived and stable cosmogenic nuclides. This would indicate a 30-40 fold increase in denudation rates since ~3000 years, which appears rather unlikely. Hence, the measured in-situ 14C concentrations may actually reflect sediment storage. Partial sediment shielding at ~80-150 cm depth is plausible from field evidence. Due to the fast decay of 14C, such shielding would result in a drop of the 14C concentration from saturation to the measured values already after several 1000 years. Nevertheless, other explanations as incomplete sediment mixing also have to be taken into account. Interestingly, our CWD long-term data agree well with short-term sediment yield data from the Altiplano (5.6-48 mm/ka) [2]. This suggests an overall uniformity in erosional processes and rates throughout the late Quaternary. The agreement between single nuclide denudation rates, despite the complex storage history, also argues for rather long-term steady-state conditions and highlights the insensitivity of long-lived cosmogenic nuclides to low amplitude, short-term variations in climate. References: [1] Plazcek et al. (2006), GSA Bulletin 118, 515-532, [2] Guyot et al. (1992), Lake Titicaca 113-119.

River fluxes to the sea from the ocean's 10Be/9Be ratio

NASA Astrophysics Data System (ADS)

von Blanckenburg, F.; Bouchez, J.

2013-12-01

The ratio of the meteoric cosmogenic radionuclide 10Be to the stable isotope 9Be is proposed here to be a flux proxy of terrigenous input into the oceans. The ocean's dissolved 10Be/9Be is set by (1) the flux of meteoric 10Be produced in the atmosphere; (2) the denudational flux of the rivers discharging into a given ocean basin; (3) the fraction of 9Be that is released from primary minerals during weathering (meaning the 9Be transported by rivers in either the dissolved form or adsorbed onto sedimentary particles and incorporated into secondary oxides); and (4) the fraction of riverine 10Be and 9Be actually released into seawater. Using published 10Be/9Be data of rivers for which independent denudation rate estimates exist we first find that the global average fraction of 9Be released during weathering into river waters and their particulate load is 20% and does not depend on denudation rate. We then evaluate this quantitative denudation rate proxy by using published dissolved seawater Be isotope data and a compilation of global river loads (15Gt/yr). We find that the measured global average oceanic dissolved 10Be/9Be ratio of about 0.9E-7 is satisfied by the mass balance if only 6.5% of the dissolved and reactive riverine Be is eventually released to the open ocean by boundary exchange. Except for the South Atlantic and the South Pacific, in which the 10Be/9Be ratio is dominated by Be advected through ocean circulation, good agreement results between 10Be/9Be ratios predicted by denudation rates and measured ocean 10Be/9Be ratios when we establish this mass balance for individual ocean basins. As the seawater 10Be/9Be ratio is faithfully recorded in marine chemical precipitates the 10Be/9Be ratio extracted from authigenic sediments can now serve to estimate relative changes in terrigenous input into the oceans back through time on a global and on a basin scale.

Luminescence of quartz and feldspar fingerprints provenance and correlates with the source area denudation in the Amazon River basin

NASA Astrophysics Data System (ADS)

Sawakuchi, A. O.; Jain, M.; Mineli, T. D.; Nogueira, L.; Bertassoli, D. J.; Häggi, C.; Sawakuchi, H. O.; Pupim, F. N.; Grohmann, C. H.; Chiessi, C. M.; Zabel, M.; Mulitza, S.; Mazoca, C. E. M.; Cunha, D. F.

2018-06-01

The Amazon region hosts the world's largest watershed spanning from high elevation Andean terrains to lowland cratonic shield areas in tropical South America. This study explores variations in optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) signals in suspended silt and riverbed sands retrieved from major Amazon rivers. These rivers drain Pre-Cambrian to Cenozoic source rocks in areas with contrasting denudation rates. In contrast to the previous studies, we do not observe an increase in the OSL sensitivity of quartz with transport distance; for example, Tapajós and Xingu Rivers show more sensitive quartz than Solimões and Madeira Rivers, even though the latter have a significantly larger catchment area and longer sediment transport distance. Interestingly, high sensitivity quartz is observed in rivers draining relatively stable Central Brazil and Guiana shield areas (denudation rate ξ = 0.04 mmyr-1), while low sensitivity quartz occurs in less stable Andean terrains (ξ = 0.24 mmyr-1). An apparent linear correlation between quartz OSL sensitivity and denudation rate suggests that OSL sensitivity may be used as a proxy for erosion rates in the Amazon basin. Furthermore, luminescence sensitivity measured in sand or silt arises from the same mineral components (quartz and feldspar) and clearly discriminates between Andean and shield sediments, avoiding the grain size bias in provenance analysis. These results have implications for using luminescence sensitivity as a proxy for Andean and shield contributions in the stratigraphic record, providing a new tool to reconstruct past drainage configurations within the Amazon basin.

Gender discrimination in the influence of hyperglycemia and hyperosmolarity on rat aortic tissue responses to insulin.

PubMed

Wong, Nikki L; Achike, Francis I

2010-08-09

Hyperglycaemia initiates endothelial dysfunction causing diabetic macro- and micro-vasculopathy, the main causes of morbidity and mortality in diabetes mellitus. The vasculopathy exhibits gender peculiarities. We therefore explored gender differences in comparing the effects of hyperglycaemia (50 mM) per se with its hyperosmolar (50 mM) effects on vascular tissue responses to insulin. Endothelium-intact or denuded thoracic aortic rings from age-matched male and female Sprague-Dawley rats were incubated for 10 min or 6 h (acute versus chronic exposure) in normal, hyperglycaemic or hyperosmolar Krebs solution. Relaxant responses to insulin (6.9x10(-7)-6.9x10(-5) M) of the phenylephrine-contracted tissues were recorded. Endothelium denudation in both genders inhibited relaxation to insulin in all conditions, more significantly in female than in male tissues, suggesting the female response to insulin is more endothelium-dependent than the male. Acutely and chronically exposed normoglycemic endothelium-intact or -denuded tissues responded similarly to insulin. Chronic hyperglycemic or hyperosmolar exposure did not alter the endothelium-denuded tissue responses to insulin, whereas the responses of the endothelium-intact male and female hyperosmolar, and male hyperglycemic tissues were enhanced. The results show that insulin exerts an endothelium-dependent and independent relaxation with the female tissue responses more endothelium-dependent than the male. The data also suggest that hyperosmolarity per se enhances aortic tissue relaxant responses to insulin whereas hyperglycemia per se inhibits the same and more so in female than male tissues. These effects are endothelium-dependent. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khairallah, Saad A.; Anderson, Andrew T.; Rubenchik, Alexander

Our study demonstrates the significant effect of the recoil pressure and Marangoni convection in laser powder bed fusion (L-PBF) of 316L stainless steel. A three-dimensional high fidelity powder-scale model reveals how the strong dynamical melt flow generates pore defects, material spattering (sparking), and denudation zones. The melt track is divided into three sections: a topological depression, a transition and a tail region, each being the location of specific physical effects. The inclusion of laser ray-tracing energy deposition in the powder-scale model improves over traditional volumetric energy deposition. It enables partial particle melting, which impacts pore defects in the denudation zone.more » Different pore formation mechanisms are observed at the edge of a scan track, at the melt pool bottom (during collapse of the pool depression), and at the end of the melt track (during laser power ramp down). Finally, we discuss remedies to these undesirable pores are discussed. The results are validated against the experiments and the sensitivity to laser absorptivity.« less

Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones

DOE PAGES

Khairallah, Saad A.; Anderson, Andrew T.; Rubenchik, Alexander; ...

2016-02-23

Our study demonstrates the significant effect of the recoil pressure and Marangoni convection in laser powder bed fusion (L-PBF) of 316L stainless steel. A three-dimensional high fidelity powder-scale model reveals how the strong dynamical melt flow generates pore defects, material spattering (sparking), and denudation zones. The melt track is divided into three sections: a topological depression, a transition and a tail region, each being the location of specific physical effects. The inclusion of laser ray-tracing energy deposition in the powder-scale model improves over traditional volumetric energy deposition. It enables partial particle melting, which impacts pore defects in the denudation zone.more » Different pore formation mechanisms are observed at the edge of a scan track, at the melt pool bottom (during collapse of the pool depression), and at the end of the melt track (during laser power ramp down). Finally, we discuss remedies to these undesirable pores are discussed. The results are validated against the experiments and the sensitivity to laser absorptivity.« less

Denudation and uplift of the Mawson Escarpment (eastern Lambert Graben, Antarctica) as indicated by apatite fission track data and geomorphological observation

USGS Publications Warehouse

Lisker, F.; Gibson, H.; Wilson, C.J.; Läufer, A.

2007-01-01

Analysis of three vertical profiles from the southern Mawson Escarpment (Lambert Graben) reveals apatite fission track (AFT) ages ranging from 102±20 to 287±23 Ma and mean lengths of 12.2 to 13.0 μm. Quantitative thermal histories derived from these data consistently indicate onset of slow cooling below 110°C began sometime prior to 300 Ma, and a second stage of rapid cooling from paleotemperatures up to ≤100°C to surface temperatures occurred in the Late Cretaceous – Paleocene. The first cooling phase refers to Carboniferous – Jurassic basement denudation up to 5 km associated with the initial rifting of the Lambert Graben. The presence of the ancient East Antarctic Erosion Surface and rapid Late Cretaceous – Paleocene cooling indicate a second denudational episode during which up to 4.5 km of sedimentary cover rocks were removed, and that is likely linked to the Cretaceous Gondwana breakup between Antarctica and India and subsequent passive continental margin formation.

Study on the application of seismic sedimentology in a stratigraphic-lithologic reservoir in central Junggar Basin

NASA Astrophysics Data System (ADS)

Yu, Yixin; Xia, Zhongmou

2017-06-01

This paper discusses the research idea of description for stratigraphic-lithologic reservoir based on seismic sedimentology methods. The sandstone reservoir of Jurrassic XiShanyao Formation in Junggar Basin is studied according to the theory and approaches of seismic sedimentology. By making full use of borehole data, the technologies of layer correlation based on the stratigraphic sequence framework, the forward seismic modeling, the stratal slicing and lithologic inversion are applied. It describes the range of denudation line, the distribution characteristics of sedimentary facies of the strata, the vertical and horizontal distribution of sand bodies and the favourable oil-gas bearing prospective area. The results shows that study area are dominated braided delta deposition including underwater distributary channel and distributary bay microfacies, the nip-out lines of the formation are northeast to southwest from north to south, the second Middle Jurassic sand body is the most widely distributed one among three sand bodies, the prospective oil-gas bearing area located in the south part and around the YG2 well area. The study result is effective on the practice of exploration in study area.

Erosional Reduction of an Orogenic Wedge: Structural Response to Neogene Climate Change within the St. Elias Orogen, Alaska

NASA Astrophysics Data System (ADS)

Berger, A. L.; Spotila, J. A.; Chapman, J. B.; Pavlis, T. L.; Enkelmann, E.; Buscher, J. T.

2007-12-01

The kinematics and architecture of orogenic systems may be heavily influenced by climate, but little research has focused on the long term effects of glacial erosion on orogenesis. Apatite and zircon (U-Th)/He thermochronometry on >75 bedrock samples across the St. Elias orogen, one of the best examples of a glaciated orogenic wedge, is the basis for a new kinematic model and demonstrates an association between glacial denudation and orogenic architecture. The spatial pattern of low temperature cooling indicates that exhumation and deformation are focused within a thin-skinned fold and thrust belt on the windward flank, whereas the leeward flank of the orogen functions as a deformational backstop. A previously unrecognized structure beneath the Bagley ice field must separate these domains with south-side-up motion. We propose this structure is a backthrust making the orogen doubly-vergent. Suggestive of accelerated backthrust motion in response to climate change, cooling rates within the hanging wall block and across the entire windward flank of the orogen accelerated ten-fold coeval with enhanced glaciation. As backthrust motion increased, glacial unroofing also coincided with a regional shift in deformation away from prominent forethrusts including the North American-Yakutat terrane suture (Chugach St. Elias fault) and the seaward deformation front (Pamplona zone). Across the windward flank of the orogen, exhumation, at rates of up to 5 mm/yr, is focused within a narrow zone, where the glacial equilibrium line altitude (ELA) intersects the orogenic wedge. This zone of rapid exhumation, not present prior to the onset of enhanced glaciation, cuts across the structural trend of the orogen and is more narrowly focused than orographic precipitation. Accelerated denudation at the ELA thus appears to have redistributed strain along a series of forethrusts that lie at the zone of heaviest glacial flux, while the backthrust progressively truncates the southward-vergent forethrusts. In a cause and effect response, the expansion of glaciers therefore appears to have resulted in a narrowing of the orogenic wedge due to increased backthrust motion and a landward propagation of deformation in order to preserve topographic slope. This focusing of long- term glacial erosion and deformation at the ELA matches predictions from analytical models of orogenic wedges (i.e. Tomkin and Braun, 2002) and implies a high degree of coupling between climate and tectonics in this glacially-dominated orogen.

Torrential landscapes associated with gravitational slope movements in BuzÄău Land Geopark, Romania - A quantitative approach on the time-space evolution of denudation processes.

NASA Astrophysics Data System (ADS)

Niculae, Lucica; Popa, Răzvan-Gabriel; Tatu, Mihai

2015-04-01

Buzău Land is an aspiring Geopark located in the southern part of the Carpathian Bend Area, covering a mountainous area to the north and hilly area to the south. The main reason for promoting this Geopark is to foster the conservation of natural and cultural heritage, in order to generate products for social and economic sustainable development. A first step in achieving this is, from an environmental point to view, to evaluate the natural hazards that may impede sustainable development in the area. Our activity, as part of a larger project targets the study of landslides, collapses and fluvial-denudation processes and the assessment of the problems that these geological and geomorphologic phenomena pose to communities and habitats. The occurrence and development of these processes are conditioned by the following factors: - precipitations per 24 hours (e.g. in 2005 values of about 80-100 mm/24 hours were recorded), which trigger severe flooding processes, landslides and mudflows; - the predisposition of rocks to erosion: the presence of non-cohesive or "soft" rocks (sand, shale, marl) and for fluvial-denudation processes the reduced moistening degree; - differences in permeability of rocks and in stiffness (sandstones and plastic shale); - anthropogenic activity such as deforestation which results in surfaces being exposed to pluvial action (national average of deforestation is of 3 Ha/hour). The intensity and space-time development of these morphogenetic processes can be evaluated by re-establishing the old drainage surfaces (early Quaternary) and by defining the volume of removed material (the eroded, transported and evacuated volume). This method was applied in Buzău Land, thus creating a clear distinction between the material displaced through landslides, the eroded material transported within the area and the material evacuated from the respective area. Calculations for denudation ratios in Buzău Land yield values between 5-11 m3/m2, for a known thalweg depth (6 and 8 m); the gullies developed on the inferior part of the slopes show values between 2-11.8 m3/m2. These values can be compared on the resulted maps. A special category of torrential forms occur on the Meledic salt plateau as a result of chemical denudation, physical denudation and intense gully erosion. The identification, quantification and monitoring of the intensity of these morphodynamic processes may contribute to the more efficient exploitation of the geomorphologic resources, in order to reduce land vulnerability and environment risk, according to the requirements of sustainable development. The research leading to these results has received funding from EEA Financial Mecanism 2009 - 2014 under the GeoSust project contract no 22 SEE/30.06.2014.

Variability over time in the sources of South Portuguese Zone turbidites: evidence of denudation of different crustal blocks during the assembly of Pangaea

NASA Astrophysics Data System (ADS)

Pereira, M. F.; Ribeiro, C.; Vilallonga, F.; Chichorro, M.; Drost, K.; Silva, J. B.; Albardeiro, L.; Hofmann, M.; Linnemann, U.

2014-07-01

This study combines geochemical and geochronological data in order to decipher the provenance of Carboniferous turbidites from the South Portuguese Zone (SW Iberia). Major and trace elements of 25 samples of graywackes and mudstones from the Mértola (Visean), Mira (Serpukhovian), and Brejeira (Moscovian) Formations were analyzed, and 363 U-Pb ages were obtained on detrital zircons from five samples of graywackes from the Mira and Brejeira Formations using LA-ICPMS. The results indicate that turbiditic sedimentation during the Carboniferous was marked by variability in the sources, involving the denudation of different crustal blocks and a break in synorogenic volcanism. The Visean is characterized by the accumulation of immature turbidites (Mértola Formation and the base of the Mira Formation) inherited from a terrane with intermediate to mafic source rocks. These source rocks were probably formed in relation to Devonian magmatic arcs poorly influenced by sedimentary recycling, as indicated by the almost total absence of pre-Devonian zircons typical of the Gondwana and/or Laurussia basements. The presence of Carboniferous grains in Visean turbidites indicates that volcanism was active at this time. Later, Serpukhovian to Moscovian turbiditic sedimentation (Mira and Brejeira Formations) included sedimentary detritus derived from felsic mature source rocks situated far from active magmatism. The abundance of Precambrian and Paleozoic zircons reveals strong recycling of the Gondwana and/or Laurussia basements. A peri-Gondwanan provenance is indicated by zircon populations with Neoproterozoic (Cadomian-Avalonian and Pan-African zircon-forming events), Paleoproterozoic, and Archean ages. The presence of late Ordovician and Silurian detrital zircons in Brejeira turbidites, which have no correspondence in the Gondwana basement of SW Iberia, indicates Laurussia as their most probable source.

Comparison and evaluation of in situ and filter carbon measurements at the Fresno Supersite

NASA Astrophysics Data System (ADS)

Watson, John G.; Chow, Judith C.

2002-11-01

The Fresno Supersite in Fresno, California, USA, acquires in situ 5- to 60-min average PM2.5 organic carbon (OC), elemental carbon (EC), and total carbon (TC) measurements by the following methods: (1) thermal evolution carbon analyzer for organic, elemental, and total carbon; (2) single-wavelength and seven-color aethalometer for black carbon (BC); and (3) photoionization for particle-bound polycyclic aromatic hydrocarbons. Twenty-four-hour average PM2.5 filter-based measurements include (1) nondenuded quartz filters with no backup filter in a PM2.5 Federal Reference Method (FRM) sampler; (2) quartz filters behind an organic carbon denuder with a quartz backup filter in a Reference Ambient Aerosol Sampler (RAAS); (3) nondenuded quartz filters with backup filter in a RAAS; and (4) nondenuded quartz filters with no backup filter in a sequential filter sampler. Filter samples are analyzed after sampling by the Interagency Monitoring of Protected Visual Environments (IMPROVE) thermal/optical reflectance carbon analysis protocol. Collocated measurements are examined for year 2000. Measurement equivalence is found for PM2.5 mass, light transmission, and TC between the FRM and RAAS speciation samplers. The average ratios of front filter carbon between the denuded and nondenuded channels in the RAAS sampler are 0.83 ± 0.19 for TC, 0.81 ± 0.20 for OC, and 1.01 ± 0.33 for EC. The average differences for TC and OC are low (1.2 to 1.4 μg m-3) and are comparable to the measurement uncertainties. Continuous thermal evolution carbon measurements are not comparable to filter measurements. Aethalometer BC and filter EC are highly correlated, but filter EC is consistently 20-25% higher than continuous aethalometer BC. Pairwise comparisons show filter EC measurements acquired in this study are predictable from aethalometer BC measurements.

Dentoalveolar growth inhibition induced by bone denudation on palates: a study of two isolated cleft palates with asymmetric scar tissue distribution.

PubMed

Ishikawa, H; Iwasaki, H; Tsukada, H; Chu, S; Nakamura, S; Yamamoto, K

1999-09-01

This report presents two cases of isolated cleft palate with asymmetric distribution of postsurgical scar tissue determined by laser Doppler flowmetry. To determine the effect of mucoperiosteal denudation of the bone on maxillary alveolar growth, the analysis of dentoalveolar structures compared the affected side to the unaffected side of each case. Two Japanese girls with isolated cleft palates were examined. Both subjects had undergone pushback operations (a modified version of the procedure of Wardill) for palatal repair at 18 months of age. Palatal blood flow was examined by laser Doppler flowmetry when the girls were 12 years old to determine the extent of postsurgical scar tissue over the denuded bone. To analyze the maxillary dentoalveolar structures three dimensionally, the whole surface of the upper dental cast was measured and recorded by an optical measuring device when the girls were 7 years old. Analysis via flowmetry showed that the palatal scar tissue area was limited to the anterior tooth region on the right (unaffected) side but extended posteriorly to the premolar region on the left (affected) side in both subjects. The two girls had similar dentoalveolar structures, with the dental and alveolar arches deflected lingually at the deciduous molar area on the affected side. There were no differences in the buccolingual inclination of deciduous molars or in the vertical growth of the alveolar processes between the affected and unaffected sides. In both girls, bone denudation in the premolar region appeared to result in less than 3 mm of displacement of the teeth palatally, with no change in lingual inclination. Any effects of scar tissue on the vertical development of the alveolus were not substantiated.

Strong climate and tectonic control on plagioclase weathering in granitic terrain

USGS Publications Warehouse

Rasmussen, C.; Brantley, S.; Richter, D.D.B.; Blum, A.; Dixon, J.; White, A.F.

2011-01-01

Investigations to understand linkages among climate, erosion and weathering are central to quantifying landscape evolution. We approach these linkages through synthesis of regolith data for granitic terrain compiled with respect to climate, geochemistry, and denudation rates for low sloping upland profiles. Focusing on Na as a proxy for plagioclase weathering, we quantified regolith Na depletion, Na mass loss, and the relative partitioning of denudation to physical and chemical contributions. The depth and magnitude of regolith Na depletion increased continuously with increasing water availability, except for locations with mean annual temperature <5??C that exhibited little Na depletion, and locations with physical erosion rates <20gm-2yr-1 that exhibited deep and complete regolith Na depletion. Surface Na depletion also tended to decrease with increasing physical erosion. Depth-integrated Na mass loss and regolith depth were both three orders of magnitude greater in the fully depleted, low erosion rate sites relative to other locations. These locations exhibited strong erosion-limitation of Na chemical weathering rates based on correlation of Na chemical weathering rate to total Na denudation. Sodium weathering rates in cool locations with positive annual water balance were strongly correlated to total Na denudation and precipitation, and exhibited an average apparent activation energy (Ea) of 69kJmol-1 Na. The remaining water-limited locations exhibited kinetic limitation of Na weathering rates with an Ea of 136kJmol-1 Na, roughly equivalent to the sum of laboratory measures of Ea and dissolution reaction enthalpy for albite. Water availability is suggested as the dominant factor limiting rate kinetics in the water-limited systems. Together, these data demonstrate marked transitions and nonlinearity in how climate and tectonics correlate to plagioclase chemical weathering and Na mass loss. ?? 2010 Elsevier B.V.

Thermal consequences of thrust faulting: simultaneous versus successive fault activation and exhumation

NASA Astrophysics Data System (ADS)

ter Voorde, M.; de Bruijne, C. H.; Cloetingh, S. A. P. L.; Andriessen, P. A. M.

2004-07-01

When converting temperature-time curves obtained from geochronology into the denudation history of an area, variations in the isotherm geometry should not be neglected. The geothermal gradient changes with depth due to heat production and evolves with time due to heat advection, if the deformation rate is high. Furthermore, lateral variations arise due to topographic effects. Ignoring these aspects can result in significant errors when estimating denudation rates. We present a numerical model for the thermal response to thrust faulting, which takes these features into account. This kinematic two-dimensional model is fully time-dependent, and includes the effects of alternating fault activation in the upper crust. Furthermore, any denudation history can be imposed, implying that erosion and rock uplift can be studied independently to each other. The model is used to investigate the difference in thermal response between scenarios with simultaneous compressional faulting and erosion, and scenarios with a time lag between rock uplift and denudation. Hereby, we aim to contribute to the analysis of the mutual interaction between mountain growth and surface processes. We show that rock uplift occurring before the onset of erosion might cause 10% to more than 50% of the total amount of cooling. We applied the model to study the Cenozoic development of the Sierra de Guadarrama in the Spanish Central System, aiming to find the source of a cooling event in the Pliocene in this region. As shown by our modeling, this temperature drop cannot be caused by erosion of a previously uplifted mountain chain: the only scenarios giving results compatible with the observations are those incorporating active compressional deformation during the Pliocene, which is consistent with the ongoing NW-SE oriented convergence between Africa and Iberia.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wesnousky, Steven G.; Briggs, Richard W.; Caffee, Marc W.

Deposits near Lamoille in the Ruby Mountains-East Humboldt Range of central Nevada and at Woodfords on the eastern edge of the Sierra Nevada each record two distinct glacial advances. In this paper, we compare independent assessments of terrestrial cosmogenic nuclide (TCN) surface exposure ages for glacial deposits that we have determined to those obtained by others at the two sites. At each site, TCN ages of boulders on moraines of the younger advance are between 15 and 30 ka and may be associated with marine oxygen isotope stage (MIS) 2. At Woodfords, TCN ages of boulders on the moraine ofmore » the older advance are younger than ~ 60 ka and possibly formed during MIS 4, whereas boulders on the correlative outwash surface show ages approaching 140 ka (~ MIS 6). The TCN ages of boulders on older glacial moraine at Woodfords thus appear to severely underestimate the true age of the glacial advance responsible for the deposit. The same is possibly true at Lamoille where clasts sampled from the moraine of the oldest advance have ages ranging between 20 and 40 ka with a single outlier age of ~ 80 ka. The underestimations are attributed to the degradation and denudation of older moraine crests. Noting that boulder ages on the older advances at each site overlap significantly with MIS 2. Finally, we speculate that erosion of the older moraines has been episodic, with a pulse of denudation accompanying the inception of MIS 2 glaciation.« less

Connective tissue graft vs. emdogain: A new approach to compare the outcomes.

PubMed

Sayar, Ferena; Akhundi, Nasrin; Gholami, Sanaz

2013-01-01

The aim of this clinical trial study was to clinically evaluate the use of enamel matrix protein derivative combined with the coronally positioned flap to treat gingival recession compared to the subepithelial connective tissue graft by a new method to obtain denuded root surface area. Thirteen patients, each with two or more similar bilateral Miller class I or II gingival recession (40 recessions) were randomly assigned to the test (enamel matrix protein derivative + coronally positioned flap) or control group (subepithelial connective tissue graft). Recession depth, width, probing depth, keratinized gingival, and plaque index were recorded at baseline and at one, three, and six months after treatment. A stent was used to measure the denuded root surface area at each examination session. Results were analyzed using Kolmogorov-Smirnov, Wilcoxon, Friedman, paired-sample t test. The average percentages of root coverage for control and test groups were 63.3% and 55%, respectively. Both groups showed significant keratinized gingival increase (P < 0.05). Recession depth decreased significantly in both groups. Root surface area was improved significantly from baseline with no significant difference between the two study groups (P > 0.05). The results of Friedman test were significant for clinical indices (P < 0.05), except for probing depth in control group (P = 0.166). Enamel matrix protein derivative showed the same results as subepithelial connective tissue graft with relatively easy procedure to perform and low patient morbidity.

Coarsening of Inter- and Intra-granular Proeutectoid Cementite in an Initially Pearlitic 2C-4Cr Ultrahigh Carbon Steel

NASA Astrophysics Data System (ADS)

Hecht, Matthew D.; Picard, Yoosuf N.; Webler, Bryan A.

2017-05-01

We have examined spheroidization and coarsening of cementite in an initially pearlitic 2C-4Cr ultrahigh carbon steel containing a cementite network. Coarsening kinetics of spheroidized cementite and growth of denuded zones adjacent to the cementite network were investigated by analyzing particle sizes from digital micrographs of water-quenched steel etched with Nital. Denuded zones grew at a rate proportional to t 1/4- t 1/5. Spheroidization of pearlite was completed within 90 minutes at 1073 K and 1173 K (800 °C and 900 °C), and within 5 minutes at 1243 K (970 °C). Bimodal particle size distributions were identified in most of the samples and were more pronounced at higher temperatures and hold times. Peaks in the distributions were attributed to the coarsening of intragranular and grain boundary particles at different rates. A third, non-coarsening peak of particles was present at 1073 K (800 °C) only and was attributed to particles existing prior to the heat treatment. Particle sizes were plotted vs time to investigate possible coarsening mechanisms. The coarsening exponent for the growth of grain boundary carbides was closest to 4, indicating grain boundary diffusion control. The coarsening exponent was closest to 5 for intragranular carbides, indicating suppression of volumetric diffusion (possibly due to reduced effective diffusivity because of Cr alloying) and control by dislocation diffusion.

Crustal solute fluxes and transient carbon dioxide drawdown in the Scottbreen Basin, Svalbard in 2002

NASA Astrophysics Data System (ADS)

Krawczyk, Wiesława Ewa; Bartoszewski, Stefan A.

2008-12-01

SummarySolute fluxes and transient carbon dioxide drawdown in a small glacierized basin investigated on Svalbard in 2002 are presented. It was a sample year within a period of significant climate warming in the Arctic. Discharge was recorded in the Scottbreen Basin (10.1 km 2), Bellsund Fjord, between July 8 and September 10, 2002. Specific runoff for this period was 0.784 m, 22% more than the mean for 1986-2001. The runoff for all of 2002 (i.e. the hydrologic year) was estimated by comparison with Bayelva, the only glacial river with longer records on Svalbard. The specific runoff for 2002 was ˜1.228 m, yielding crustal solute fluxes of 69.4 t km -2 yr -1 (25.8 m 3 km -2 yr -1). This rate is the highest chemical denudation rate reported from glacierized basins on Svalbard, and it may be underestimated because higher solute fluxes at the beginning of the melt season were not taken into account. Crustal fluxes in the fall may also have been higher because it is probable that crustal ion concentrations were increasing after recording stopped in September. The cation denudation rate was 1213 ∑ meq + m -2 yr -1 and the mean annual crustal ion concentration derived from it amounted to 981 μeq L -1. Transient CO 2 drawdown in 2002 was 5242 kg C km -2 yr -1. Most of the carbon dioxide was removed in the summer ablation waters, estimated CO 2 drawdown in the fall being only 13% of the total. Comparison with crustal solute fluxes (CSF) computed from specific conductivity in the 1980s and 1990s suggests that earlier fluxes may have been overestimated by around 19%. Comparing earlier data with the 2002 rates may confirm the influence of climate warming on increasing chemical denudation rates. It was also found that a globally derived equation relating specific conductivity to concentrations of dissolved limestone in water gave estimates of the crustal solute fluxes that were only 1.1% less than those obtained via comprehensive chemical analyses of waters and ion partitioning procedures.

The posterior nasoseptal flap: A novel technique for closure after endoscopic transsphenoidal resection of pituitary adenomas

PubMed Central

Barger, James; Siow, Matthew; Kader, Michael; Phillips, Katherine; Fatterpekar, Girish; Kleinberg, David; Zagzag, David; Sen, Chandranath; Golfinos, John G.; Lebowitz, Richard; Placantonakis, Dimitris G.

2018-01-01

Background: While effective for the repair of large skull base defects, the Hadad-Bassagasteguy nasoseptal flap increases operative time and can result in a several-week period of postoperative crusting during re-mucosalization of the denuded nasal septum. Endoscopic transsphenoidal surgery for pituitary adenoma resection is generally not associated with large dural defects and high-flow cerebrospinal fluid (CSF) leaks requiring extensive reconstruction. Here, we present the posterior nasoseptal flap as a novel technique for closure of skull defects following endoscopic resection of pituitary adenomas. This flap is raised in all surgeries during the transnasal exposure using septal mucoperiosteum that would otherwise be discarded during the posterior septectomy performed in binostril approaches. Methods: We present a retrospective, consecutive case series of 43 patients undergoing endoscopic transsphenoidal resection of a pituitary adenoma followed by posterior nasoseptal flap placement and closure. Main outcome measures were extent of resection and postoperative CSF leak. Results: The mean extent of resection was 97.16 ± 1.03%. Radiographic measurement showed flap length to be adequate. While a defect in the diaphragma sellae and CSF leak were identified in 21 patients during surgery, postoperative CSF leak occurred in only one patient. Conclusions: The posterior nasoseptal flap provides adequate coverage of the surgical defect and is nearly always successful in preventing postoperative CSF leak following endoscopic transsphenoidal resection of pituitary adenomas. The flap is raised from mucoperiosteum lining the posterior nasal septum, which is otherwise resected during posterior septectomy. Because the anterior septal cartilage is not denuded, raising such flaps avoids the postoperative morbidity associated with the larger Hadad-Bassagasteguy nasoseptal flap. PMID:29527390

Implementing a conceptual model of physical and chemical soil profile evolution

NASA Astrophysics Data System (ADS)

Kirkby, Mike

2017-04-01

When soil profile composition is generalised in terms of the proportion, p, of bedrock remaining (= 1 - depletion ratio), then other soil processes can also be expressed in terms of p, and 'soil depth' described by the integral of (1-p) down to bedrock. Soil profile evolution is expressed as the advance of a sigmoidal weathering front into the critical zone under the action of upward ionic diffusion of weathering products; downward advection of solutes in percolating waters, with loss of (cleanish) water as evapotranspiration and (solute-laden) water as a lateral sub-surface flow increment; and mechanical denudation increment at the surface. Each component responds to the degree of weathering. Percolation is limited by precipitation, evapotranspiration demand and the degree of weathering at each level in the profile which diverts subsurface flow. Mechanical removal rates are considered to broadly increase as weathering proceeds, as grain size and dilation angle decreases. The implication of these assumptions can be examined for steady state profiles, for which observed relationships between mechanical and chemical denudation rates; and between chemical denudation and critical zone depth are reproduced. For non-steady state evolution, these relationships break down, but provide a basis for linking critical zone with hillslope/ landform evolution.

Evaluation of the Sequential Spot Sampler (S3) for time-resolved measurement of PM2.5 sulfate and nitrate through lab and field measurements

NASA Astrophysics Data System (ADS)

Hecobian, A.; Evanoski-Cole, A.; Eiguren-Fernandez, A.; Sullivan, A. P.; Lewis, G. S.; Hering, S. V.; Collett, J. L., Jr.

2016-02-01

The Sequential Spot Sampler (S3), a newly developed instrument to collect aerosols for time-resolved chemical composition measurements, was evaluated in the laboratory and field for the measurement of particulate sulfate and nitrate. The S3 uses a multi-temperature condensation growth tube to grow individual aerosols to droplets which are then deposited as a ˜ 1 mm diameter dry spot at the end of the growth tube in a 100 µL well of a multi-well plate. The well plate advances automatically to provide a sequence of time-resolved samples. The collected aerosols are subsequently analyzed in the laboratory. The sample is concentrated during the collection process, and the laboratory extraction and analysis steps can be automated. The well plate, as received from the field, is placed onto a needle-based autosampler that adds liquid for sample extraction and injects sample extract from each well onto an ion chromatograph for analysis. Laboratory evaluation for sulfate and nitrate ions showed that poly ether ether ketone (PEEK) used as well plate material does not contribute any artifacts; a 60 min extraction procedure leads to the recovery of sulfate and nitrate from the dry spots at above 95 % extraction efficiency; and samples stored frozen and analyzed up to 23 months later show less than a 10 % change in sulfate and nitrate concentrations. The limit of detection was 0.5 µg m-3 for sulfate and 0.2 µg m-3 for nitrate for a 1 h sampling period. In a month-long field study conducted in southern California, two S3s were deployed alongside a URG denuder-filter-pack and a Particle-Into-Liquid Sampler combined with an Ion Chromatograph (PILS-IC). Collocated S3 sampler concentrations compared by linear regression show good agreement, with r2 = 0.99 and slope = 0.99 (±0.004) µg m-3 for sulfate and r2 = 0.99 and slope = 1.0 (±0.006) µg m-3 for nitrate. When compared to the URG denuder-filter-pack and the PILS-IC, the S3 sulfate and nitrate concentrations yielded correlations above 0.84 for the square of the correlation coefficient and regression slopes close to 1.

Activation of thermal denudation under recent climatic fluctuations, Central Yamal, Russia

NASA Astrophysics Data System (ADS)

Khomutov, Artem; Dvornikov, Yury; Gubarkov, Anatoly; Mullanurov, Damir

2016-04-01

Climatic fluctuations over the past few years significantly affected the increase of cryogenic processes activity in the tundra zone of the Yamal Peninsula. On Central Yamal a large-scale cryogenic landsliding was observed in 1989, while cryogenic earth flows were actively developing since 2012 through tabular ground ice thawing. As a result, thermocirques form on lakeshores. Key area (research station "Vaskiny Dachi" on the Se-Yakha and the Mordy-Yakha interfluve) during the period from 1989 to 2012 was characterized by a local occurrence of thermal denudation. By 2010, remote sensing data showed that this process in the study area was usually inactive and thermocirques looked stabilized, overgrown by vegetation. Extremely warm summer of 2012 resulted in formation of new thermal denudation features, such as cryogenic translational landslides, cryogenic earth flows and furthermore, thermocirques, complex landforms resulting from ice wedges and tabular ground ice thaw. The 2012 warm season was characterized by a deeper active layer: at the end of the warm period deeper by 15% than the average for the 1993-2011. Observed were indications of a high pore pressure in the active layer: effuse of liquefied clay in the tension cracks on many slopes. By 2013, according to the field and remote sensing data, there were more than 90 active thermal denudation landforms from 66 to 25000 sq.m in size on the territory of 345 sq.km. Thus, at the present in the tundra of the Yamal Peninsula the predominance of the processes associated with tabular ground ice thawing (cryogenic earth flows) over the processes associated with the ice formation at the bottom of the active layer (cryogenic translational landslides) is observed. It is caused by both a periodic deepening of the active layer, and consecutive increase of ground temperature. Activation of thermal denudation observed on the Yamal Peninsula last years is associated with extremely warm spring and summer of 2012. By the end of the warm season thawing of the top of icy permafrost and tabular ground ice on some slopes resulted in cryogenic landsliding and further thermocirques development. The study is partially supported by RFBR, research project No.13-05-91001-ANF_a; ASF No I 1401-N29; and The Presidential Council for grants, Science School Grant No.3929.2014.5.

Carbonyl atmospheric reaction products of aromatic hydrocarbons in ambient air

NASA Astrophysics Data System (ADS)

Obermeyer, Genevieve; Aschmann, Sara M.; Atkinson, Roger; Arey, Janet

To convert gaseous carbonyls to oximes during sampling, an XAD-4 resin denuder system pre-coated with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine and followed by analysis with methane positive chemical ionization gas chromatography/mass spectrometry was used to measure carbonyls in ambient air samples in Riverside, CA. In conjunction with similar analyses of environmental chamber OH radical-initiated reactions of o- and p-xylene, 1,2,4-trimethylbenzene, ethylbenzene, 4-hydroxy-2-butanone and 1,4-butanediol, we identified benzaldehyde, o-, m- and p-tolualdehyde and acetophenone and the dicarbonyls glyoxal, methylglyoxal, biacetyl, ethylglyoxal, 1,4-butenedial, 3-hexene-2,5-dione, 3-oxo-butanal, 1,4-butanedial and malonaldehyde in the ambient air samples. As discussed, these carbonyls and dicarbonyls can be formed from the OH radical-initiated reactions of aromatic hydrocarbons and other volatile organic compounds emitted into the atmosphere, and we conclude that in situ atmospheric formation is a major source of these carbonyls in our Riverside, CA, ambient air samples.

Precipitation of silicon from splat-cooled Al-Si alloys

NASA Technical Reports Server (NTRS)

Matyja, H.; Russell, K. C.; Grant, N. J.; Giessen, B. C.

1975-01-01

Splat cooled Al-Si solid solutions with 1 to 11 at.% Si were prepared and their precipitation kinetics were studied by transmission electron microscopy. The time required for appearance of particles visible at a magnification of 35,000 times was determined at temperatures between 248 K and 573 K. The resulting Arrhenius plots yielded activation energies ranging from 55 to 40 plus or minus 2kJ/mol over the composition range. Precipitate densities were higher and denuded zones of 100 to 150 nm were narrower than in comparable solid quenched samples. The activation energies are explained in terms of excess point defect concentrations.

Live imaging of collagen deposition during skin development and repair in a collagen I - GFP fusion transgenic zebrafish line.

PubMed

Morris, Josephine L; Cross, Stephen J; Lu, Yinhui; Kadler, Karl E; Lu, Yongbo; Dallas, Sarah L; Martin, Paul

2018-06-06

Fibrillar collagen is a major component of many tissues but has been difficult to image in vivo using transgenic approaches because of problems associated with establishing cells and organisms that generate GFP-fusion collagens that can polymerise into functional fibrils. Here we have developed and characterised GFP and mCherry collagen-I fusion zebrafish lines with basal epidermal-specific expression. We use these lines to reveal the dynamic nature of collagen-I fibril deposition beneath the developing embryonic epidermis, as well as the repair of this collagen meshwork following wounding. Transmission electron microscope studies show that these transgenic lines faithfully reproduce the collagen ultrastructure present in wild type larval skin. During skin development we show that collagen I is deposited by basal epidermal cells initially in fine filaments that are largely randomly orientated but are subsequently aligned into a cross-hatch, orthogonal sub-epithelial network by embryonic day 4. Following skin wounding, we see that sub-epidermal collagen is re-established in the denuded domain, initially as randomly orientated wisps that subsequently become bonded to the undamaged collagen and aligned in a way that recapitulates developmental deposition of sub-epidermal collagen. Crossing our GFP-collagen line against one with tdTomato marking basal epidermal cell membranes reveals how much more rapidly wound re-epithelialisation occurs compared to the re-deposition of collagen beneath the healed epidermis. By use of other tissue specific drivers it will be possible to establish zebrafish lines to enable live imaging of collagen deposition and its remodelling in various other organs in health and disease. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Multiple, discrete inversion episodes revealed by apatite fission track analysis along the southernmost Atlantic margin of South Africa

NASA Astrophysics Data System (ADS)

Wildman, M.; Brown, R. W.; Persano, C.; Stuart, F. M.

2013-12-01

The morpho-tectonic history of the western South African continental margin and interior plateau remains enigmatic. Recent investigations of offshore sediment accumulation and interpretations of onshore structural and geomorphological observations have highlighted the complex geological evolution of South Africa throughout the Mesozoic and Cenozoic. Moreover, advances in geodynamic modelling approaches have explored the crustal response to varying styles of rifting and the influence of mantle upwelling beneath the African plate. These geological observations and models, however, require validation from quantitative constraints on the surface response (i.e. uplift and erosion) to syn- and post rift thermal and tectonic processes Over the last two decades, low temperature thermochronometry, particularly apatite fission track analysis (AFTA) and apatite (U-Th)/He, have been effective tools in providing these constraints by tracking the time-temperature history of rocks through c. 60 - 110°C and 80 - 40°C, respectively. The unique ability of AFTA to constrain both the timing and nature of sample cooling rests largely on the sensitivity of fission track annealing to temperature. Here, we present new AFT data from a suite of samples across the entire western continental margin of South Africa which contributes to a now extensive AFT dataset spanning the entire sub-continent. This dataset broadly invokes at least two discrete episodes of cooling driven by km scale denudation at c. 130 Ma, following rifting and break up of West Gondwana, and 90 Ma as a response to renewed tectonic uplift. However, the apparent lack of correlation of AFT age with elevation or with distance from the coast highlight the spatial and temporal variability of post-rift cooling that may be related to Mid-Cretaceous structural reactivation along the margin. We also present thermal history modelling using the Bayesian transdimensional inverse modelling approach of QTQt (Gallagher, 2012). Modelling was performed for several outcrop samples, including a 604 m vertical profile, and two borehole profiles from the interior plateau with bottom depths of 2.5 (QU 1/65) and 6.2 km (KC 1/70). The results of this novel modelling approach are interpreted alongside independent on and offshore geological observations to lend additional support to the occurrence of multiple, discrete episodes of denudation driven cooling at c. 150 - 130 and 90 Ma, and possibly a later Cretaceous episode of cooling at c. 70 Ma. The existence of a Late Cretaceous or younger period of enhanced denudation is being further explored through ongoing work combining new AFT data with apatite (U-Th)/He data to generate more robust thermal history information and provide new insights into the timing and magnitude of the major periods of uplift and erosion that have formed the first order topography of South Africa. Gallagher, K., 2012, Transdimensional inverse thermal history modeling for quantitative thermochronology: Journal of Geophysical Research: Solid Earth, v. 117(B2).

Himalayan tectonics explained by extrusion of a low-viscosity crustal channel coupled to focused surface denudation.

PubMed

Beaumont, C; Jamieson, R A; Nguyen, M H; Lee, B

2001-12-13

Recent interpretations of Himalayan-Tibetan tectonics have proposed that channel flow in the middle to lower crust can explain outward growth of the Tibetan plateau, and that ductile extrusion of high-grade metamorphic rocks between coeval normal- and thrust-sense shear zones can explain exhumation of the Greater Himalayan sequence. Here we use coupled thermal-mechanical numerical models to show that these two processes-channel flow and ductile extrusion-may be dynamically linked through the effects of surface denudation focused at the edge of a plateau that is underlain by low-viscosity material. Our models provide an internally self-consistent explanation for many observed features of the Himalayan-Tibetan system.

Measurements of particulate semi-volatile material

NASA Astrophysics Data System (ADS)

Pang, Yanbo

2000-10-01

A new innovative sampling system, PC-BOSS, was developed by the combination of particle concentrator and BOSS denuder techniques in response to the new EPA PM2.5 standard and to meet top research priorities for particulate matter that were identified by the National Research Council. The PC-BOSS (P_article C_oncentrator- B_righam Young University O_rganic S_ampling S_ystem) can accurately determine not only PM2.5 stable mass and species such as sulfate, but also particulate semi- volatile material. Several field comparison studies of the PC-BOSS with the EPA PM2.5 reference method and state-of-the-art fine particle measurement methods confirm the capability of the PC-BOSS to accurately determine particulate semi-volatile material, especially organic compounds. This is the first routine sampling system for the determination of both particulate semi-volatile inorganic and organic material. Two other denuder system samplers for the determination of PM2.5 total mass including semi-volatile material were also developed for PM2.5 research and exposure monitoring. Results of studies around the United States indicate that the EPA PM2.5 FRM (Federal Reference Method) under- measured PM2.5 mass by 20-30% compared to PC-BOSS results due to the loss of particulate nitrate and semi-volatile organic compounds during sampling. Organic material is mostly responsible for this under- measurement by the FRM. Using our new sampling system in epidemiological and exposure studies will be essential to providing answers to some top research priorities for particulate matter and promote a better PM2.5 standard for the protection of human health because some fractions of particulate semi-volatile organic compounds are toxic and are possibly responsible for health effects associated with exposure to particulate matter. The atmospheric chemistry of organic aerosols in the troposphere and stratosphere is still largely unknown because of the lack of detailed organic aerosol information. The importance of organic aerosols might also be underestimated because current data on organic aerosols in the troposphere and stratosphere were mostly obtained by traditional methods, like the FRM method. Using PC-BOSS to study organic aerosols in the troposphere and stratosphere will provide not only more but also more accurate information about organic aerosols, and significantly improve the understanding of the role of aerosols in global warming, ozone depletion, and atmospheric heterogenous chemistry.

Development and application of denuder sampling techniques with in situ derivatization for the determination of hydrogenbromide in volcanic plumes

NASA Astrophysics Data System (ADS)

Gutmann, Alexandra; Rüdiger, Julian; Hoffmann, Thorsten

2016-04-01

The composition of gases in volcanic plumes shifts with subsurface processes inside volcanoes. For monitoring volcanic activity by studying volcanic plumes it is essential to understand the chemical reactions inside the volcanic plume (Bobrowski and Platt, 2013). Measurements of BrO/SO2-ratio already enable insights into magmatic processes (Bobrowski and Giuffrida, 2012). Both, BrO and SO2, are measurable by Remote Sensing Techniques at a safe distance. Models suggest not a direct emission of BrO but formation due to photochemical and multiphase reactions in the gas and particle phase. These model presume HBr as first emitted species (Gerlach, 2004). So HBr is an important connecting link between easily measurable BrO/SO2-ratios and conclusions on a volcanic system. It is of high importance to know if there is a variation in the amount of HBr transformed into BrO and to gain knowledge on the factor of its dependence. Apart from depletion of surrounded ozone also decreasing or depletion of emitted HBr or even HCl could be responsible for the shift (Bobrowski and Giuffrida, 2012). Knowledge about complex processes in volcanic plumes will simplify interpretation and predictions. In this study, first applications of coated gas diffusion denuder (similar to Huang and Hoffmann, 2008) to derivatize gaseous HBr were successful. Due to the lack of adequate remote sensing techniques an in situ method was developed and will be presented in detail. The epoxide of oleic acid was determined as a suitable derivatization agent. The reaction with HBr gives 10-bromo-9-hydroxyoctadecanoic acid. Other hydrogenhalogens give corresponding products. Derivatized analytes were removed from denuder by solvent elution and subsequent analysed with gas chromatography-mass spectrometry. A limit of quantification below 1 ng was achieved. The method was applied on volcanic gas plumes at Mt. Etna in Italy in July and August 2015. The results showed HBr in higher ppt-range. These first proof-of-principle investigations showed the suitability of the method for halogenhalides-analysis. References Bobrowski, N. and Giuffrida, G.: Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006-2009, Solid Earth, 3, 433-445, doi:10.5194/se-3-433-2012, 2012. Bobrowski, N. and Platt, U.: Den Himmel betrachten, die Hölle verstehen. Telegramm aus dem Inneren der Erde., Ruperto Carola, 2013, 2013. Gerlach, T. M.: Volcanic sources of tropospheric ozone-depleting trace gases, Geochem. Geophys. Geosyst., 5, n/a, doi:10.1029/2004GC000747, 2004. Huang, R.-J. and Hoffmann, T.: A denuder-impinger system with in situ derivatization followed by gas chromatography-mass spectrometry for the determination of gaseous iodine-containing halogen species, Journal of Chromatography A, 1210, 135-141, doi:10.1016/j.chroma.2008.08.003, 2008.

Endothelium-Dependent and -Independent Vasodilator Effects of Dimethyl Sulfoxide in Rat Aorta.

PubMed

Kaneda, Takeharu; Sasaki, Noriyasu; Urakawa, Norimoto; Shimizu, Kazumasa

2016-01-01

This study examined the mechanism of vasorelaxation induced by dimethyl sulfoxide (DMSO) in endothelium-intact and -denuded rat aorta. DMSO (0.1-3%) inhibited phenylephrine (PE, 1 μmol/l)-induced contraction in a dose-dependent manner. However, this relaxation was lower in the absence of the endothelium. Increase in DMSO-induced relaxation in the presence of the endothelium was attenuated by preincubation in L-NG-nitroarginine methyl ester (L-NAME, 100 μmol/l) and by the removal of the endothelium. In the aorta with endothelium, DMSO (3%) and CCh (3 μmol/l) increased cGMP contents, significantly and L-NAME (100 μmol/l) inhibited the DMSO-induced increases of cGMP. In fura 2-loaded endothelium-denuded aorta, cumulative application of DMSO (1-3%) inhibited PE-induced muscle tension; however, this application did not affect the [Ca2+]i level. In PE-precontracted endothelium-denuded aorta, relaxation responses to fasudil were significantly less in the presence of DMSO compared to the control. These results suggest that DMSO causes relaxation by increasing the cGMP content in correlation with the release of NO from endothelial cells and by decreasing the Ca2+ sensitivity of contractile elements partly via inhibiting Rho-kinase in rat aorta. © 2016 S. Karger AG, Basel.

Effects of sub-chronic oral cyanide on endothelial function in rabbit aortic rings.

PubMed

Ozolu, R I; Okolie, N P; Ebeigbe, A B; Karikari, N

2007-02-01

We have investigated how the endothelium affects vascular responses following sub-chronic low dose cyanide administration. Cyanide exists in low levels in cassava foods, which are widely consumed in tropical Africa. Adult rabbits were administered 0.38 mg/kg per day KCN po for 25 days, and responses of the isolated aortic rings to noradrenaline (NA), calcium chloride (Ca2+) and acetylcholine (ACh) were measured in vitro in the presence and absence of the endothelium. In order to establish that the dose was not toxic, animal weight, some haematological indices, plasma alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were measured. Results show that endothelium denudation significantly (P <0.05) attenuates NA-induced contraction in rings from cyanide-treated rabbits. There was a similar reduction in response in Ca2+-depleted NA-precontracted endothelium-denuded aortic rings from cyanide-treated rabbits. Endothelium-denuded rings from cyanide-treated rabbits showed significantly (P <0.05) enhanced relaxation to ACh. In rings from control animals, the responses to NA and Ca2+ were not significantly altered, whether in the presence or absence of the endothelium. There were no significant changes in the studied toxicological indices. We conclude that endothelial compromise is necessary for low-dose sub-chronic cyanide-induced to alter vascular reactivity to NA and ACh.

A full mass spectrum evaluation of semivolatile organic compounds measured during the Southern Oxidant and Aerosol Study in Alabama, USA, 2013

NASA Astrophysics Data System (ADS)

Holzinger, Rupert; Khan, Anwar; Misztal, Pawel; Goldstein, Allen

2016-04-01

A serial 3-stage denuder system has been developed and for the first time deployed during the Southern Oxidant and Aerosol Study (SOAS) in Centreville, Alabama, USA, for one month during the summer of 2013. Volatile organic compounds (VOCs) were collected on an activated carbon denuder and thermally desorbed to be measured with PTR-MS (PTR-TOF800, Ionicon Analytik GmbH). Comparison with a second PTR-MS instrument operated under standard conditions at the same site revealed poor recovery for the majority of the VOCs while individual species measured by the different PTR-MS systems still exhibited excellent correlation. Semivolatile organic compounds (SVOCs) in the gas phase were collected and thermally desorbed on a denuder coated with Methylsiloxane (Agilent DB-1). More than 100 SVOCs have been detected at levels in the range 0.05-3 pmmol/mol and only a few species exhibited maximum mixing ratios above 5 pmol/mol. Many of the detected species exhibited a clear diurnal profile while the concentration of some was clearly dominated by pollution events. Carboxylic acids, (oxidized) polycyclic aromatic compounds, and monoterpene oxidation products were compound groups that provided most of the mass and a typical total concentration of the measured burden of SVOCs was 5 microgram per cubic meter.

Recycling of Pleistocene valley fills dominates 125 ka of sediment flux, upper Indus River

NASA Astrophysics Data System (ADS)

Munack, Henry; Blöthe, Jan Henrik; Fülöp, Réka-Hajnalka; Codilean, Alexandru T.; Fink, David; Korup, Oliver

2016-04-01

Rivers draining the semiarid Transhimalayan Ranges along the western Tibetan Plateau margin underwent alternating phases of massive valley infill and incision in Pleistocene times. The imprints of these cut-and-fill cycles on long-term sediment fluxes have remained largely elusive. We investigate the timing and geomorphic consequences of headward incision of the Zanskar River, which taps the vast More Plains valley fill that currently impedes drainage of the endorheic high-altitude basins of Tso Kar and Tso Moriri. In situ 10Be exposure dating and topographic analyses indicate that a phase of valley infill gave way to net dissection of the >250-m thick sedimentary stacks ˜125 ka ago, i.e. during the last interglacial (MIS 5e). Rivers eroded >14.7 km3 of sediment from the Zanskar headwaters since then, fashioning specific sediment yields that surpass 10Be-derived denudation rates from neighbouring catchments by factors of two to ten. We conclude that recycling of Pleistocene valley fills has provided Transhimalayan headwater rivers with more sediment than bedrock denudation, at least since the beginning of the last glacial cycle. This protracted liberation of sediment stored in thick valley fills could bias rate estimates of current sediment loads and long-term bedrock denudation.

Geochemical and tectonic uplift controls on rock nitrogen inputs across terrestrial ecosystems

NASA Astrophysics Data System (ADS)

Morford, Scott L.; Houlton, Benjamin Z.; Dahlgren, Randy A.

2016-02-01

Rock contains > 99% of Earth's reactive nitrogen (N), but questions remain over the direct importance of rock N weathering inputs to terrestrial biogeochemical cycling. Here we investigate the factors that regulate rock N abundance and develop a new model for quantifying rock N mobilization fluxes across desert to temperate rainforest ecosystems in California, USA. We analyzed the N content of 968 rock samples from 531 locations and compiled 178 cosmogenically derived denudation estimates from across the region to identify landscapes and ecosystems where rocks account for a significant fraction of terrestrial N inputs. Strong coherence between rock N content and geophysical factors, such as protolith, (i.e. parent rock), grain size, and thermal history, are observed. A spatial model that combines rock geochemistry with lithology and topography demonstrates that average rock N reservoirs range from 0.18 to 1.2 kg N m-3 (80 to 534 mg N kg-1) across the nine geomorphic provinces of California and estimates a rock N denudation flux of 20-92 Gg yr-1 across the entire study area (natural atmospheric inputs ~ 140 Gg yr-1). The model highlights regional differences in rock N mobilization and points to the Coast Ranges, Transverse Ranges, and the Klamath Mountains as regions where rock N could contribute meaningfully to ecosystem N cycling. Contrasting these data to global compilations suggests that our findings are broadly applicable beyond California and that the N abundance and variability in rock are well constrained across most of the Earth system.

Quaternary landscape development, alluvial fan chronology and erosion of the Mecca Hills at the southern end of the San Andreas Fault zone

USGS Publications Warehouse

Gray, Harrison J.; Owen, Lewis A.; Dietsch, Craig; Beck, Richard A.; Caffee, Marc A.; Finkelman, Robert B.; Mahan, Shannon

2014-01-01

Quantitative geomorphic analysis combined with cosmogenic nuclide 10Be-based geochronology and denudation rates have been used to further the understanding of the Quaternary landscape development of the Mecca Hills, a zone of transpressional uplift along the southern end of the San Andreas Fault, in southern California. The similar timing of convergent uplifts along the San Andreas Fault with the initiation of the sub-parallel San Jacinto Fault suggest a possible link between the two tectonic events. The ages of alluvial fans and the rates of catchment-wide denudation have been integrated to assess the relative influence of climate and tectonic uplift on the development of catchments within the Mecca Hills. Ages for major geomorphic surfaces based on 10Be surface exposure dating of boulders and 10Be depth profiles define the timing of surface stabilization to 2.6 +5.6/–1.3 ka (Qyf1 surface), 67.2 ± 5.3 ka (Qvof2 surface), and 280 ± 24 ka (Qvof1 surface). Comparison of 10Be measurements from active channel deposits (Qac) and fluvial terraces (Qt) illustrate a complex history of erosion, sediment storage, and sediment transport in this environment. Beryllium-10 catchment-wide denudation rates range from 19.9 ± 3.2 to 149 ± 22.5 m/Ma and demonstrate strong correlations with mean catchment slope and with total active fault length normalized by catchment area. The lack of strong correlation with other geomorphic variables suggests that tectonic uplift and rock weakening have the greatest control. The currently measured topography and denudation rates across the Mecca Hills may be most consistent with a model of radial topographic growth in contrast to a model based on the rapid uplift and advection of crust.

Present morphoclimate and morphodynamics in the boreal Homla drainage basin system (Trøndelag, middle Norway)

NASA Astrophysics Data System (ADS)

Beylich, Achim A.

2017-04-01

It is generally accepted that ongoing and future climate change will cause major changes in Earth surface systems and environments. From a geomorphological point of view, it is accordingly of increasing importance to obtain a better understanding of the relationships between contemporary geomorphological processes and present-day climatic conditions to come to more reliable assessments of the possible geomorphological effects of climate change. Until recently, the present-day climate has often only been characterized by monthly and annual means or sum values of wind speed, air temperature and precipitation. As most geomorphological surface processes consist of discrete events which are only partly correlated to these meteorological means or sum values, there is an obvious need for an additional approach of statistical analysis of meteorological data. In this study the "morphoclimate" of the Homla drainage basin situated in a boreal environment in Trøndelag in middle Norway is analyzed. "Morphoclimate" according to Ahnert (e.g., 1982) is specially related to geomorphological needs and, in this sense, is defined as the totality of those climatic characteristics of an area that influence the type, frequency, duration and intensity of the exogenic geomorphologic processes in this area. The statistical method primarily used in this context is the magnitude-frequency analysis. Particular emphasis is on (i) the frequencies or recurrence intervals of meteorological events of given magnitudes, and (ii) the frequencies of geomorphologically important thresholds. Aspects of the current wind, temperature and precipitation regimes which control the type, frequency, duration and intensity of the contemporary denudational surface processes as well as the sedimentary budget in the selected study area are presented. Runoff in the boreal Homla drainage basin is occurring year-round and the contemporary morphodynamics are altogether characterized by a clear dominance of chemical denudation over mechanical fluvial denudation. The general intensity of the denudational surface processes operating under the present-day morphoclimate is low.

The extent of adhesion induction through electrocoagulation and suturing in an experimental rat study.

PubMed

Wallwiener, Christian W; Kraemer, Bernhard; Wallwiener, Markus; Brochhausen, Christoph; Isaacson, Keith B; Rajab, Taufiek K

2010-03-01

To investigate the effect of three types of peritoneal trauma occurring during surgery (high-frequency bipolar current, suturing, and mechanical damage) on postoperative adhesion formation in a rodent animal model. Randomized, controlled experimental trial in an in vitro animal model. Laboratory facilities of a university department of obstetrics and gynecology. Thirty-five female Wistar rats. Bilateral experimental lesions were created on the abdominal wall in every animal. The effect of minimal electrocoagulation was examined by creating lesions (n = 14) through sweeps of a bipolar forceps with a duration of 1 second and standardized pressure. For extensive electrocoagulation standardized lesions (n = 14) were created using sweeps of a duration of 3 seconds and three times more pressure. For mechanical trauma, standardized lesions (n = 14) were created by denuding the peritoneum mechanically. To study the additive effect of suturing, experimental lesions were created by suturing plus minimal electrocoagulation (n = 14) or mechanical denuding (n = 14). Adhesion incidence, quantity, and quality of the resulting adhesions were scored 14 days postoperatively. Adhesions were studied histopathologically. Mechanical denuding of the peritoneum did not result in adhesion formation. After minimal electrocoagulation, mean adhesion quantity of the traumatized area averaged 0%. This contrasted with extensive electrocoagulation, where there was 50% adhesion. Additional suturing increased mean adhesion quantity to 73% and 64% for superficial electrocoagulation and mechanical denuding, respectively. We conclude that superficial trauma limited mostly to the parietal peritoneum may be a negligible factor in adhesion formation in this model. This appears to be irrespective of the mode of trauma. However, additional trauma to the underlying tissues, either by deeper electrocoagulation or suturing, leads to significantly increased adhesion formation. These data also show that there is a spectrum of electrocoagulation trauma at the lower end of which there is little adhesion formation. Copyright 2010 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

MASCOT: a new mass-spectrometer facility dedicated to the analysis of cosmogenic noble gases (3He and 21Ne) from terrestrial samples (Institute of Geological Sciences - University of Bern, Switzerland).

NASA Astrophysics Data System (ADS)

Delunel, Romain; Enderli, Patrick; Jenni, Hans-Erich; Leya, Ingo; Schlunegger, Fritz

2017-04-01

In the past years, terrestrial cosmogenic nuclides have been successfully used for dating exposure history of landforms and measuring erosional processes on Earth's surface. In this context, quantifications of landscape change have mainly been accomplished through the use of radioactive cosmogenic nuclides such as 10Be and 26Al, but their application has generally been restricted to Quaternary time scales because of their relatively short half-lives. The results are 10Be and 26Al concentrations that are below the detection limit of available accelerator mass spectrometers if the samples have a Late Miocene or even a Pliocene age. Contrariwise, cosmogenic noble gases such as 3He and 21Ne do not experience any radioactive decay through time, which places these isotopes in an unbeatable position for measuring paleo-denudation rates preserved in detrital material even if the ages of these deposits are up to 10 Ma and even older. These isotopes are thus keys for assessing the interplays between tectonic, climate and surface processes involved in the long-term evolution of mountain belts. Here we report the technical specifications of a noble gas analytical system that we have developed and set up at the Institute of Geological Sciences of the University of Bern, Switzerland, with the motivations to get dates and rates of erosion processes from the measurement of cosmogenic noble gases (3He and 21Ne) concentrations from terrestrial samples. This new facility, hosted at the Institute of Geological Sciences of the University of Bern, combines a MAP215-50 mass spectrometer fitted with a new high-sensitivity channel electron multiplier with an all-metal extraction and purification line. This later system thus comprises: (i) a double vacuum resistance furnace loaded by a 22-samples carrousel, (ii) three in-vacuo crushers (iii) an ultra high vacuum pumping system (<10-8 mbar) composed of turbo-molecular, ion-getter pumps and backed by a scroll pump, (iv) the line itself made up of a series of valves, connectors, a collection of getter-pellets filled fingers and activated charcoal cold-traps and (v) a dry-cryogen free cryostat system operating at temperatures ranging between 8K and 375K for trapping remaining heavy gases and focusing He and/or Ne before analysis in the mass spectrometer. This communication will be the opportunity to present our new noble gas system's full specifications together with an overview of the associated scientific questions we want to address using this new facility.

Bedrock Denudation on Titan: Estimates of Vertical Extent and Lateral Debris Dispersion

NASA Technical Reports Server (NTRS)

Moore, Jeffrey; Howard, A. D.; Schenk, Paul Michael

2013-01-01

Methane rainfall and runoff, along with aeolian activity, have dominated the sculpting of Titan s landscape. A knowledge of the vertical extent of bedrock erosion and the lateral extent of the resulting sediment is useful for several purposes [1]. For instance, what is the magnitude and expression of modification of constructional landforms (e.g., mountains)? Does highland denudation and the filling of basins with sediment cause adjustments (uplift and subsidence) in the crustal ice shell? Here we report preliminary findings of putative eroded craters and the results of landform evolution modeling (Fig. 1) that suggest that approx. 250 m of net bedrock erosion has at least locally taken place and approx.1 km of maximum local erosion.

Physical and chemical controls on the critical zone

USGS Publications Warehouse

Anderson, S.P.; Von Blanckenburg, F.; White, A.F.

2007-01-01

Geochemists have long recognized a correlation between rates of physical denudation and chemical weathering. What underlies this correlation? The Critical Zone can be considered as a feed-through reactor. Downward advance of the weathering front brings unweathered rock into the reactor. Fluids are supplied through precipitation. The reactor is stirred at the top by biological and physical processes. The balance between advance of the weathering front by mechanical and chemical processes and mass loss by denudation fixes the thickness of the Critical Zone reactor. The internal structure of this reactor is controlled by physical processes that create surface area, determine flow paths, and set the residence time of material in the Critical Zone. All of these impact chemical weathering flux.

Bubble evolution in Kr-irradiated UO2 during annealing

NASA Astrophysics Data System (ADS)

He, L.; Bai, X. M.; Pakarinen, J.; Jaques, B. J.; Gan, J.; Nelson, A. T.; El-Azab, A.; Allen, T. R.

2017-12-01

Transmission electron microscopy observation of Kr bubble evolution in polycrystalline UO2 annealed at high temperature was conducted in order to understand the inert gas behavior in oxide nuclear fuel. The average diameter of intragranular bubbles increased gradually from 0.8 nm in as-irradiated sample at room temperature to 2.6 nm at 1600 °C and the bubble size distribution changed from a uniform distribution to a bimodal distribution above 1300 °C. The size of intergranular bubbles increased more rapidly than intragranular ones and bubble denuded zones near grain boundaries formed in all the annealed samples. It was found that high-angle grain boundaries held bigger bubbles than low-angle grain boundaries. Complementary atomistic modeling was conducted to interpret the effects of grain boundary character on the Kr segregation. The area density of strong segregation sites in the high-angle grain boundaries is much higher than that in the low angle grain boundaries.

Campholenic aldehyde ozonolysis: a mechanism leading to specific biogenic secondary organic aerosol constituents

NASA Astrophysics Data System (ADS)

Kahnt, A.; Iinuma, Y.; Mutzel, A.; Böge, O.; Claeys, M.; Herrmann, H.

2014-01-01

In the present study, campholenic aldehyde ozonolysis was performed to investigate pathways leading to specific biogenic secondary organic aerosol (SOA) marker compounds. Campholenic aldehyde, a known α-pinene oxidation product, is suggested to be a key intermediate in the formation of terpenylic acid upon α-pinene ozonolysis. It was reacted with ozone in the presence and absence of an OH radical scavenger, leading to SOA formation with a yield of 0.75 and 0.8, respectively. The resulting oxidation products in the gas and particle phases were investigated employing a denuder/filter sampling combination. Gas-phase oxidation products bearing a carbonyl group, which were collected by the denuder, were derivatised by 2,4-dinitrophenylhydrazine (DNPH) followed by liquid chromatography/negative ion electrospray ionisation time-of-flight mass spectrometry analysis and were compared to the gas-phase compounds detected by online proton-transfer-reaction mass spectrometry. Particle-phase products were also analysed, directly or after DNPH derivatisation, to derive information about specific compounds leading to SOA formation. Among the detected compounds, the aldehydic precursor of terpenylic acid was identified and its presence was confirmed in ambient aerosol samples from the DNPH derivatisation, accurate mass data, and additional mass spectrometry (MS2 and MS3 fragmentation studies). Furthermore, the present investigation sheds light on a reaction pathway leading to the formation of terpenylic acid, involving α-pinene, α-pinene oxide, campholenic aldehyde, and terpenylic aldehyde. Additionally, the formation of diaterpenylic acid acetate could be connected to campholenic aldehyde oxidation. The present study also provides insights into the source of other highly functionalised oxidation products (e.g. m / z 201, C9H14O5 and m / z 215, C10H16O5), which have been observed in ambient aerosol samples and smog chamber-generated monoterpene SOA. The m / z 201 and 215 compounds were tentatively identified as a C9- and C10-carbonyl-dicarboxylic acid, respectively, based on reaction mechanisms of campholenic aldehyde and ozone, as well as detailed interpretation of mass spectral data, in conjunction with the formation of corresponding DNPH derivatives.

Campholenic aldehyde ozonolysis: a possible mechanism for the formation of specific biogenic secondary organic aerosol constituents

NASA Astrophysics Data System (ADS)

Kahnt, A.; Iinuma, Y.; Mutzel, A.; Böge, O.; Claeys, M.; Herrmann, H.

2013-08-01

In the present study, campholenic aldehyde ozonolysis was performed to investigate pathways leading to specific biogenic secondary organic aerosol (SOA) marker compounds. Campholenic aldehyde, a known α-pinene oxidation product, is suggested to be a key intermediate in the formation of terpenylic acid upon α-pinene ozonolysis. It was reacted with ozone in the presence and absence of an OH radical scavenger leading to SOA formation with a yield of 0.75 and 0.8, respectively. The resulting oxidation products in the gas and particle phases were investigated employing a denuder/filter sampling combination. Gas-phase oxidation products bearing a carbonyl group, which were collected by the denuder, were derivatised with 2,4-dinitrophenylhydrazine (DNPH) followed by Liquid Chromatography/negative ion Electrospray Ionisation Time-of-Flight Mass Spectrometry analysis and were compared to the gas-phase compounds detected by online Proton-Transfer-Reaction Mass Spectrometry. Particle-phase products were also analysed, directly or after DNPH derivatisation, to derive information about specific compounds leading to SOA formation. Among the detected compounds, the aldehydic precursor of terpenylic acid was identified and its presence was confirmed in ambient aerosol samples from the DNPH derivatisation, accurate mass data, and MS2 and MS3 fragmentation studies. Furthermore, the present investigation sheds light on a reaction pathway leading to the formation of terpenylic acid, involving α-pinene, α-pinene oxide, campholenic aldehyde, and terpenylic aldehyde. Additionally, the formation of diaterpenylic acid acetate could be connected to campholenic aldehyde oxidation. The present study also provides insights into the source of other highly functionalised oxidation products (e.g. m/z 201, C9H14O5 and m/z 215, C10H16O5), which have been observed in ambient aerosol samples and smog chamber-generated monoterpene SOA. The m/z 201 and 215 compounds were tentatively identified as a C9- and C10-carbonyl-dicarboxylic acid, respectively, based on reaction mechanisms of campholenic aldehyde and ozone, detailed interpretation of mass spectral data, in conjunction with the formation of corresponding DNPH-derivatives.

Quantifying the influence of sediment source area sampling on detrital thermochronometer data

NASA Astrophysics Data System (ADS)

Whipp, D. M., Jr.; Ehlers, T. A.; Coutand, I.; Bookhagen, B.

2014-12-01

Detrital thermochronology offers a unique advantage over traditional bedrock thermochronology because of its sensitivity to sediment production and transportation to sample sites. In mountainous regions, modern fluvial sediment is often collected and dated to determine the past (105 to >107 year) exhumation history of the upstream drainage area. Though potentially powerful, the interpretation of detrital thermochronometer data derived from modern fluvial sediment is challenging because of spatial and temporal variations in sediment production and transport, and target mineral concentrations. Thermochronometer age prediction models provide a quantitative basis for data interpretation, but it can be difficult to separate variations in catchment bedrock ages from the effects of variable basin denudation and sediment transport. We present two examples of quantitative data interpretation using detrital thermochronometer data from the Himalaya, focusing on the influence of spatial and temporal variations in basin denudation on predicted age distributions. We combine age predictions from the 3D thermokinematic numerical model Pecube with simple models for sediment sampling in the upstream drainage basin area to assess the influence of variations in sediment production by different geomorphic processes or scaled by topographic metrics. We first consider a small catchment from the central Himalaya where bedrock landsliding appears to have affected the observed muscovite 40Ar/39Ar age distributions. Using a simple model of random landsliding with a power-law landslide frequency-area relationship we find that the sediment residence time in the catchment has a major influence on predicted age distributions. In the second case, we compare observed detrital apatite fission-track age distributions from 16 catchments in the Bhutan Himalaya to ages predicted using Pecube and scaled by various topographic metrics. Preliminary results suggest that predicted age distributions scaled by the rock uplift rate in Pecube are statistically equivalent to the observed age distributions for ~75% of the catchments, but may improve when scaled by local relief or specific stream power weighted by satellite-derived precipitation. Ongoing work is exploring the effect of scaling by other topographic metrics.

Tectonic/climatic control on sediment provenance in the Cape Roberts Project core record (southern Victoria Land, Antarctica): A pulsing late Oligocene/early Miocene signal from south revealed by detrital thermochronology

NASA Astrophysics Data System (ADS)

Olivetti, V.; Balestrieri, M. L.; Rossetti, F.; Talarico, F. M.

2012-04-01

The Mesozoic-Cenozoic West Antarctic Rift System (WARS) is one of the largest intracontinental rift on Earth. The Transantarctic Mountains (TAM) form its western shoulder, marking the boundary between the East and West Antarctica. The rifting evolution is commonly considered polyphase and involves an Early Cretaceous phase linked to the Gondwana break-up followed by a major Cenozoic one, starting at c. 50-40 Ma. This Cenozoic episode corresponds to the major uplift/denudation phase of the TAM, which occurred concurrently with transition from orthogonal to oblique rifting. The Cenozoic rift reorganization occurred concurrently with a major change in the global climate system and a global reorganization of plate motions. This area thus provide an outstanding natural laboratory for studying a range of geological problems that involve feedback relationships between tectonics and climate. A key to address the tectonic/climate feedback relations is to look on apparent synchronicity in erosion signal between different segments, and to compare these with well-dated regional and global climatic events. However, due to the paucity of Cenozoic rock sequences exposed along the TAM front, a few information is available about the neotectonics of the rift and rift-flank uplift system. The direct physical record of the tectonic/climate history of the WARS recovered by core drillings along the western margin of the Ross sea (DSDP, CIROS, Cape Roberts and ANDRILL projects) provides an invaluable tool to address this issue. Twenty-three samples distributed throughout the entire composite drill-cored stratigraphic succession of Cape Roberts were analyzed. Age probability plots of eighteen detrital samples with depositional ages between 34 Ma and the Pliocene were decomposed into statistically significant age populations or peaks using binomial peak-fitting. Moreover, three granitic pebbles, one dolerite clast and one sample of Beacon sandstones have been dated. From detrital samples, three peaks are detected reflecting different bedrock provenance areas. Two peaks older than 40 Ma (P2 and P3) are compatible with thermochronological data from TAM bedrock that underwent a stepwise denudation in Cretaceous times. A Peak younger than 40 Ma (P1) has been detected occasionally, recording the signal of a source area exhumed during late Oligocene /early Miocene with a constant denudation rate of 0.4 mm/yr (constant lag-time up-section), but absent in the onshore portion of the proximal TAM. Indeed, when compared with AFT data from ANDRILL cores, the relatively young P1 ages, suggest that part of sediments in the Cape Robert Rift basin have a provenance from source regions probably located far away in the south (i.e. Skelton-Byrd glaciers region) where bedrock experienced compatible thermal histories. This provenance would imply glacial systems with main flow patterns from south to the north, therefore orthogonal to the orientation of present-day drainage. We thus infer that the post-Eocene glacial and erosional history of the TAM front was significantly controlled by the N-S-trending transtensional regime that affected the western Ross Sea margin during transition from orthogonal to oblique rifting in the region. The appearance and disappearance of P1 along the drill-cored stratigraphic succession seems to be linked to the oscillation in the extent of the ice sheet.

Chemical weathering rate, denudation rate, and atmospheric and soil CO2 consumption of Paraná flood basalts in São Paulo State, Brazil

NASA Astrophysics Data System (ADS)

da Conceição, Fabiano Tomazini; dos Santos, Carolina Mathias; de Souza Sardinha, Diego; Navarro, Guillermo Rafael Beltran; Godoy, Letícia Hirata

2015-03-01

The chemical weathering rate and atmospheric/soil CO2 consumption of Paraná flood basalts in the Preto Stream basin, São Paulo State, Brazil, were evaluated using major elements as natural tracers. Surface and rain water samples were collected in 2006, and analyses were performed to assess pH, temperature, dissolved oxygen (DO), electrical conductivity (EC) and total dissolved solids (TDS), including SO42-, NO3-, PO43 -, HCO3-, Cl-, SiO2, Ca2 +, Mg2 +, Na+ and K+. Fresh rocks and C horizon samples were also collected, taking into account their geological context, abundance and spatial distribution, to analyze major elements and mineralogy. The Preto Stream, downstream from the city of Ribeirão Preto, receives several elements/compounds as a result of anthropogenic activities, with only sulfate yielding negative flux values. The negative flux of SO42 - can be attributed to atmospheric loading that is mainly related to anthropogenic inputs. After corrections were made for atmospheric inputs, the riverine transport of dissolved material was found to be 30 t km- 2 y- 1, with the majority of the dissolved material transported during the summer (wet) months. The chemical weathering rate and atmospheric/soil CO2 consumption were 6 m/Ma and 0.4 · 106 mol km- 2 y- 1, respectively. The chemical weathering rate falls within the lower range of Paraná flood basalt denudation rates between 135 and 35 Ma previously inferred from chronological studies. This comparison suggests that rates of basalt weathering in Brazil's present-day tropical climate differ by at most one order of magnitude from those prevalent at the time of hothouse Earth. The main weathering process is the monosiallitization of anorthoclase, augite, anorthite and microcline. Magnetite is not weathered and thus remains in the soil profile.

Involvement of purines and phosphoinositides in spontaneous and progesterone-induced nuclear maturation of Bufo arenarum oocytes.

PubMed

Zelarayán, L; Oterino, J; Sánchez Toranzo, G; Bühler, M I

2000-07-01

Although progesterone is the established maturation inducer in amphibia, it has been demonstrated that Bufo arenarum oocytes resume meiosis with no need of an exogenous hormonal stimulus if deprived of their enveloping follicle cells, a phenomenon called "spontaneous maturation." The present studies were designed to evaluate the participation of purines and phosphoinositides in the spontaneous and progesterone-induced maturation in Bufo arenarum full-grown oocytes. The presented data demonstrate that high intracellular levels of purines such as cAMP or guanosine can inhibit both spontaneous and progesterone-induced maturation in full-grown denuded Bufo arenarum oocytes. Moreover, the fact that the mycophenolic acid was able to induce maturation in denuded oocytes obtained during the nonreproductive period in a manner similar to that of the progesterone and also to increase the percentages of spontaneous maturation suggests that in Bufo arenarum, inosine monophosphate dehydrogenase inhibition is an important step in the resumption of meiosis. Inhibition of the phosphatidylinositol 4,5 bisphosphate hydrolysis by treatment of denuded oocytes with neomycin totally blocks spontaneous and progesterone-induced maturation, suggesting that the products of this hydrolysis (1,2 diacylglycerol and inositol 1,4,5 trisphosphate) may be involved in the maturation process of Bufo. In addition, our results indicate that the activation of protein kinase C is also involved in both types of maturation.

Developmental potential of murine germinal vesicle stage cumulus-oocyte complexes following exposure to dimethylsulphoxide or cryopreservation: loss of membrane integrity of cumulus cells after thawing.

PubMed

Ruppert-Lingham, C J; Paynter, S J; Godfrey, J; Fuller, B J; Shaw, R W

2003-02-01

Cumulus cells of the cumulus-oocyte complex (COC) are important in oocyte maturation. Thus, in preserving immature oocytes it is prudent to also preserve their associated cumulus cells. The survival and function of oocytes and their associated cumulus cells was assessed following cryopreservation or exposure to cryoprotectant without freezing. Immature COCs were collected from mice primed with pregnant mare's serum. COCs were either slow-cooled or exposed to 1.5 mol/l dimethylsulphoxide without freezing. Treated and fresh COCs were stained for membrane integrity or, after in-vitro maturation and IVF, were assessed for developmental capability. Development of cumulus-denuded fresh oocytes, as well as denuded and frozen-thawed oocytes co-cultured with fresh cumulus cells, was assessed. Slow-cooled oocytes had significantly reduced coverage by intact cumulus cells compared with fresh COCs. Cumulus cell association and developmental capability were not substantially affected by exposure to cryoprotectant without freezing. Denuded fresh oocytes and cryopreserved COCs had decreased developmental potential that was not overcome by co-culture with fresh cumulus cells. Loss of association between oocyte and cumulus cells was induced by cryopreservation, but not by treatment with cryoprotectant alone. The data indicate that direct physical contact between cumulus cells and the oocyte, throughout maturation, improves subsequent embryo development.

Characteristics of Sediment Transportation in Two Contrasting Oak Forested Watersheds in the Lesser Central Himalaya, India

NASA Astrophysics Data System (ADS)

Qazi, N. U. Q.; Bruijnzeel, S., Sr.; Rai, S. P., Sr.

2015-12-01

Sediment transfer from mountainous areas to lowland areas is one of the most important geomorphological processes globally with the bulk of the sediment yield from such areas typically deriving from mass wastage processes. This study presents monthly, seasonal and annual variations in sediment transport (both suspended load and bedload) as well as dissolved loads over three consecutive water years (2008-2011) for two small forested watersheds with contrasting levels of forest disturbance in the Lesser Himalaya of Northwest India. Seasonal and annual suspended sediment yields were strongly influenced by amounts of rainfall and streamflow and showed a 10-63 fold range between wet and dry years. Of the annual load, some 93% was produced on average during the monsoon season (June-September). Sediment production by the disturbed forest catchment was 1.9-fold (suspended sediment) to 5.9-fold (bedload) higher than that for the well-stocked forest catchment. By contrast, dissolved loads varied much less between years, seasons (although minimal during the dry summer season), and degree of forest disturbance. Total mechanical denudation rates were 1.6 times and 4.6 times larger than chemical denudation rates for the little disturbed and the heavily disturbed forest catchment, respectively whereas overall denudation rates were estimated at 0.69 and 1.04 mm per 1000 years, respectively.

Temporal Variability of Suspended Sediment Load, Dissolved Load, and Bedload for Two Small Oak Forested Catchments with Contrasting Disturbance Levels in the Lesser Himalaya of North-West India

NASA Astrophysics Data System (ADS)

Qazi, N. U. Q.; Rai, S. P.; Bruijnzeel, L. A.

2014-12-01

Sediment transfer from mountainous areas to lowland areas is one of the most important geomorphological processes globally with the bulk of the sediment yield from such areas typically deriving from mass wastage processes. This study presents monthly, seasonal and annual variations in sediment transport (both suspended load and bed load) as well as dissolved loads over three consecutive water years (2008-2011) for two small forested watersheds with contrasting levels of forest disturbance in the Lesser Himalaya of Northwest India. Seasonal and annual suspended sediment yields were strongly influenced by amounts of rainfall and stream flow and showed a 23-fold range between wet and dry years. Of the annual load, some 92% was produced on average during the monsoon season (June-September). Sediment production by the disturbed forest catchment was 2.6-fold (suspended sediment) to 5.9-fold (bed load) higher than that for the well-stocked forest catchment. By contrast, dissolved loads varied much less between years, seasons (although minimal during the dry summer season), and degree of forest disturbance. Total mechanical denudation rates were 1.2 times and 4.7 times larger than chemical denudation rates for the little disturbed and the heavily disturbed forest catchment, respectively whereas overall denudation rates were estimated at 0.59 and 1.05 mm per 1000 years, respectively.

Tropospheric GOM at the Pic du Midi Observatory-Correcting Bias in Denuder Based Observations.

PubMed

Marusczak, Nicolas; Sonke, Jeroen E; Fu, Xuewu; Jiskra, Martin

2017-01-17

Gaseous elemental mercury (GEM, Hg) emissions are transformed to divalent reactive Hg (RM) forms throughout the troposphere and stratosphere. RM is often operationally quantified as the sum of particle bound Hg (PBM) and gaseous oxidized Hg (GOM). The measurement of GOM and PBM is challenging and under mounting criticism. Here we intercompare six months of automated GOM and PBM measurements using a Tekran (TK) KCl-coated denuder and quartz regenerable particulate filter method (GOM TK , PBM TK , and RM TK ) with RM CEM collected on cation exchange membranes (CEMs) at the high altitude Pic du Midi Observatory. We find that RM TK is systematically lower by a factor of 1.3 than RM CEM . We observe a significant relationship between GOM TK (but not PBM TK ) and Tekran flush TK blanks suggesting significant loss (36%) of labile GOM TK from the denuder or inlet. Adding the flush TK blank to RM TK results in good agreement with RM CEM (slope = 1.01, r 2 = 0.90) suggesting we can correct bias in RM TK and GOM TK . We provide a bias corrected (*) Pic du Midi data set for 2012-2014 that shows GOM* and RM* levels in dry free tropospheric air of 198 ± 57 and 229 ± 58 pg m -3 which agree well with in-flight observed RM and with model based GOM and RM estimates.

Soil catenas on denudation plains in the forest-tundra and northern taiga zones of the Kola Peninsula

NASA Astrophysics Data System (ADS)

Urusevskaya, I. S.

2017-07-01

Morphogenetic features of soils of two catenas developed on sandy to loamy sandy moraine deposits in the forest-tundra and northern taiga zones on denudation plains of the Kola Peninsula are discussed. It is shown that these catenas are similar with respect to the major directions of soil formation, regularities of soil distribution by the elements of mesotopography, and the factors of the soil cover differentiation. The differences between the catenas are of quantitative character and are related to the intensities of manifestation of the particular processes and features. Both catenas are characterized by the pronounced differentiation of soils with respect to their moistening with hydromorphic peat bog soils in the subordinate positions and Al-Fe-humus podzols in the automorphic positions.

Extreme rates of riverbank erosion of the high bluff formed by the ice-rich syngenetic permafrost (yedoma), Itkillik River, Northern Alaska

NASA Astrophysics Data System (ADS)

Kanevskiy, M. Z.; Shur, Y.; Fortier, D.; Jorgenson, T.; Stephani, E.; Strauss, J.

2013-12-01

Riverbank erosion in areas underlain by ice-rich permafrost is strongly affected by the processes of thawing of ground ice, which include (1) thermal erosion, and (2) thermal denudation. Thermal erosion is a process of combined thermal and mechanical action of moving water, which results in simultaneous thawing of frozen soil and its removal by water. Thermal erosion can cause block collapse of eroded banks. Thermal denudation is a process of thawing of frozen soils exposed in the bluff due to solar energy and consequent removal of thawed soils by gravity. Studies of riverbank and coastal erosion revealed that the highest rates of erosion are typical of bluffs composed by yedoma (ice- and organic-rich syngenetically frozen silty deposits). Yedoma deposits can be up to 50 m thick, and they contain huge ice wedges up to 10 m wide. Since 2006, we have studied the process of riverbank erosion of the 35 m high exposure of yedoma along the Itkillik River in northern Alaska. Based on five measurements of the areas occupied by wedge ice in panoramic photographs taken in 2006, 2007, 2011, and 2012, the average wedge-ice volume makes 61% of the entire exposed bluff. The total volumetric ground ice content of the Itkillik yedoma, including wedge, segregated and pore ice, is 85%. We detect three main stages of the riverbank erosion for the study site and other similar sites in the areas of ice-rich permafrost: (1) thermal erosion combined with thermal denudation, (2) thermal denudation, and (3) slope stabilization. The first stage includes formation of thermoerosional niches; development of sub-vertical cracks and block-fall collapse of cornices; and thawing and disintegration of blocks of ground ice and frozen soil in the water. All these processes are accompanied by thermal denudation of the exposed bluff. On August 16, 2007, a big portion of the bluff fell down along the crack sub-parallel to the bluff. As a result, the vertical wall more than 65 m long entirely formed by the wedge ice was exposed. This block-fall affected the area of approximately 800 m2, and the volume of frozen soil and ice involved in the block-fall was about 15,000 m3. The riverbank retreat due to thermal erosion and/or thermal denudation, measured from August 2007 to August 2011, varied from less than 10 to almost 100 m. An estimated retreat rate average for the whole 680 m long bluff was 11.4 m/year, but for the most actively eroded central part of the bluff (150 m long) it was 20.3 m/year, ranging from 16 to 24 m/year. During these 4 years, about 650,000 m3 of ice and organic-rich frozen soil were transported to the river from the retreating bank (more than 160,000 m3/year). Analysis of aerial photographs (1948-1979) and satellite images (1974-2013) showed that the riverbank was relatively stable till July 1995, when the Itkillik River changed its course and triggered extremely active thermal erosion. The total retreat of the riverbank in 1995-2010 varied from 180 to 280 m, which means that the average retreat rate for the most actively eroded part of the riverbank reached almost 19 m/year. Such a high rate of riverbank erosion over a long time period has not been reported before for any permafrost regions of Eurasia and North America.

Terrestrial cosmogenic surface exposure dating of glacial and associated landforms in the Ruby Mountains-East Humboldt Range of central Nevada and along the northeastern flank of the Sierra Nevada

DOE PAGES

Wesnousky, Steven G.; Briggs, Richard W.; Caffee, Marc W.; ...

2016-05-07

Deposits near Lamoille in the Ruby Mountains-East Humboldt Range of central Nevada and at Woodfords on the eastern edge of the Sierra Nevada each record two distinct glacial advances. In this paper, we compare independent assessments of terrestrial cosmogenic nuclide (TCN) surface exposure ages for glacial deposits that we have determined to those obtained by others at the two sites. At each site, TCN ages of boulders on moraines of the younger advance are between 15 and 30 ka and may be associated with marine oxygen isotope stage (MIS) 2. At Woodfords, TCN ages of boulders on the moraine ofmore » the older advance are younger than ~ 60 ka and possibly formed during MIS 4, whereas boulders on the correlative outwash surface show ages approaching 140 ka (~ MIS 6). The TCN ages of boulders on older glacial moraine at Woodfords thus appear to severely underestimate the true age of the glacial advance responsible for the deposit. The same is possibly true at Lamoille where clasts sampled from the moraine of the oldest advance have ages ranging between 20 and 40 ka with a single outlier age of ~ 80 ka. The underestimations are attributed to the degradation and denudation of older moraine crests. Noting that boulder ages on the older advances at each site overlap significantly with MIS 2. Finally, we speculate that erosion of the older moraines has been episodic, with a pulse of denudation accompanying the inception of MIS 2 glaciation.« less

Terrestrial cosmogenic surface exposure dating of glacial and associated landforms in the Ruby Mountains-East Humboldt Range of central Nevada and along the northeastern flank of the Sierra Nevada

USGS Publications Warehouse

Wesnousky, Steven G.; Briggs, Richard; Caffee, Marc W.; Ryerson, Rick J.; Finkel, Robert C.; Owen, Lewis A.

2016-01-01

Deposits near Lamoille in the Ruby Mountains-East Humboldt Range of central Nevada and at Woodfords on the eastern edge of the Sierra Nevada each record two distinct glacial advances. We compare independent assessments of terrestrial cosmogenic nuclide (TCN) surface exposure ages for glacial deposits that we have determined to those obtained by others at the two sites. At each site, TCN ages of boulders on moraines of the younger advance are between 15 and 30 ka and may be associated with marine oxygen isotope stage (MIS) 2. At Woodfords, TCN ages of boulders on the moraine of the older advance are younger than ~ 60 ka and possibly formed during MIS 4, whereas boulders on the correlative outwash surface show ages approaching 140 ka (~ MIS 6). The TCN ages of boulders on older glacial moraine at Woodfords thus appear to severely underestimate the true age of the glacial advance responsible for the deposit. The same is possibly true at Lamoille where clasts sampled from the moraine of the oldest advance have ages ranging between 20 and 40 ka with a single outlier age of ~ 80 ka. The underestimations are attributed to the degradation and denudation of older moraine crests. Noting that boulder ages on the older advances at each site overlap significantly with MIS 2. We speculate that erosion of the older moraines has been episodic, with a pulse of denudation accompanying the inception of MIS 2 glaciation.

The inhibitory effect of 3-amino-1,2,4-triazole on relaxation induced by hydroxylamine and sodium azide but not hydrogen peroxide or glyceryl trinitrate in rat aorta.

PubMed Central

Mian, K. B.; Martin, W.

1995-01-01

1. In this study we investigated the role of catalase in relaxation induced by hydroxylamine, sodium azide, glyceryl trinitrate and hydrogen peroxide in isolated rings of rat aorta. 2. Hydrogen peroxide (1 microM-1 mM)-induced concentration-dependent relaxation of phenylephrine (PE)-induced tone in endothelium-containing rings. In endothelium-denuded rings, however, higher concentrations (30 microM-1 mM) of hydrogen peroxide were required to produce relaxation. The endothelium-dependent component of hydrogen peroxide-induced relaxation was abolished following pretreatment with N(O)-nitro-L-arginine methyl ester (L-NAME, 30 microM). L-NAME (30 microM) had no effect, however, on hydrogen peroxide-induced relaxation in endothelium-denuded rings. 3. Pretreatment of endothelium-denuded rings with catalase (1000 u ml-1) blocked relaxation induced by hydrogen peroxide (10 microM-1 mM). The ability of catalase to inhibit hydrogen peroxide-induced relaxation was partially blocked following incubation with 3-amino-1,2, 4-triazole (AT, 50 mM) for 30 min and completely blocked at 90 min. 4. Pretreatment of endothelium-denuded rings with methylene blue (MeB, 30 microM) inhibited relaxation induced by hydrogen peroxide (10 microM-1 mM), sodium azide (1-300 nM), hydroxylamine (1-300 nM) and glyceryl trinitrate (1-100 nM) suggesting that each acted by stimulation of soluble guanylate cyclase. 5. Pretreatment of endothelium-denuded rings with AT (1-50 mM, 90 min) to inhibit endogenous catalase blocked relaxation induced by sodium azide (1-300 nM) and hydroxylamine (1-300 nM) but had no effect on relaxation induced by hydrogen peroxide (10 microM-1 mM) or glyceryl trinitrate (1-100 nM). 6. In a cell-free system, incubation of sodium azide (10 microM-3 mM) and hydroxylamine (10 microM-30 mM) but not glyceryl trinitrate (10 microM-1 mM) with catalase (1000 u ml-1) in the presence of hydrogen peroxide (1 mM) led to production of nitrite, a major breakdown product of nitric oxide. AT (1-100 mM) inhibited, in a concentration-dependent manner, the formation of nitrite from azide in the presence of hydrogen peroxide. 7. These data suggest that metabolism by catalase plays an important role in the relaxation induced by hydroxylamine and sodium azide in isolated rings of rat aorta. Relaxation appears to be due to formation of nitric oxide and activation of soluble guanylate cyclase. In contrast, metabolism by catalase does not appear to be involved in the relaxant actions of hydrogen peroxide or glyceryl trinitrate. PMID:8719811

River fluxes to the sea from the oceanʼs 10Be/9Be ratio

NASA Astrophysics Data System (ADS)

von Blanckenburg, Friedhelm; Bouchez, Julien

2014-02-01

The ratio of the meteoric cosmogenic radionuclide 10Be to the stable isotope 9Be is proposed here to be a flux proxy of terrigenous input into the oceans. The ocean's dissolved 10Be/9Be is set by (1) the flux of meteoric 10Be produced in the atmosphere; (2) the denudational flux of the rivers discharging into a given ocean basin; (3) the fraction of 9Be that is released from primary minerals during weathering (meaning the 9Be transported by rivers in either the dissolved form or adsorbed onto sedimentary particles and incorporated into secondary oxides); and (4) the fraction of riverine 10Be and 9Be actually released into seawater. Using published 10Be/9Be data of rivers for which independent denudation rate estimates exist we first find that the global average fraction of 9Be released during weathering into river waters and their particulate load is 20% and does not depend on denudation rate. We then evaluate this quantitative proxy for terrigenous inputs by using published dissolved seawater Be isotope data and a compilation of global river loads. We find that the measured global average oceanic dissolved 10Be/9Be ratio of about 0.9×10-7 is satisfied by the mass balance if only about 6% of the dissolved and adsorbed riverine Be is eventually released to the open ocean after escaping the coastal zone. When we establish this mass balance for individual ocean basins good agreement results between 10Be/9Be ratios predicted from known river basin denudation rates and measured ocean 10Be/9Be ratios. Only in the South Atlantic and the South Pacific the 10Be/9Be ratio is dominated by advected Be and in these basins the ratio is a proxy for ocean circulation. As the seawater 10Be/9Be ratio is faithfully recorded in marine chemical precipitates the 10Be/9Be ratio extracted from authigenic sediments can now serve to estimate relative changes in terrigenous input into the oceans back through time on a global and on an ocean basin scale.

Relationship between knee pain and the presence, location, size and phenotype of femorotibial denuded areas of subchondral bone as visualized by MRI.

PubMed

Cotofana, S; Wyman, B T; Benichou, O; Dreher, D; Nevitt, M; Gardiner, J; Wirth, W; Hitzl, W; Kwoh, C K; Eckstein, F; Frobell, R B

2013-09-01

Conflicting associations between imaging biomarkers and pain in knee osteoarthritis (OA) have been reported. A relation between pain and denuded areas of subchondral bone (dABs) has been suggested and this study explores this relationship further by relating the presence, phenotype, location and size of dABs to different measures of knee pain. 633 right knees from the Osteoarthritis Initiative (OAI) (250 men, age 61.7 ± 9.6 yrs, BMI 29.4 ± 4.7 kg/m(2)) were included. Manual segmentation of the femorotibial cartilage plates was performed on 3 T coronal fast low angle shot with water excitation (FLASHwe) images. dABs were defined as areas where the subchondral bone was uncovered by cartilage. The following measures of pain were used: weightbearing-, non-weightbearing-, moderate-to-severe-, infrequent- and frequent knee pain. Using pain measures from subjects without dABs as a reference, those with at least one dAB had a 1.64-fold higher prevalence ratio [PR, 95% confidence interval (CI) 1.24-2.18] to have frequent and 1.45-fold higher for moderate-to-severe knee pain (95% CI 1.13-1.85). Subjects with dABs in central subregions had a 1.53-fold increased prevalence of having weightbearing pain (95% CI 1.20-1.97), especially when the central subregion was moderately (>10%) denuded (PR 1.81, 95% CI 1.35-2.42). Individuals with cartilage-loss-type dABs had a slightly higher prevalence (PR 1.13, 95% CI 1.00-1.27) of having frequent knee pain compared to individuals with intra-chondral-osteophyte-type dABs. This study supports a positive relation between femorotibial dABs and knee pain, especially when the dABs are located centrally (i.e., in weightbearing regions) or when the respective central subregion is moderately denuded. Copyright © 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Tool Belts: Latitudinal-Belt Predictions for the Persistence of Landscapes

NASA Astrophysics Data System (ADS)

Willenbring, Jane; Brocard, Gilles

2016-04-01

The ability of rivers to cut through rock and re-establish equilibrium sets the pace of landscape response to uplift. Because of associations between tectonics, erosion, and weathering, high rates of rock uplift may initiate a cascade of processes that are linked to high rates of weathering and eventually sequestration of CO2 over geologic timescales. How long does it take to completely change the topographic form after uplift and where on Earth do relict landscapes persist despite uplift? Large expanses of subdued landscapes are common at high elevation in mountain ranges. Preservation of subdued fragments amongst steeply dissected regions can therefore be a simple matter of chance, reflecting the time it takes for dissection to remove any remaining parcel of the pre-existing topography after a tectonic perturbation. Some of these relicts may, however, possess characteristics - often a product of the climate - that make them intrinsically resistant to dissection. One common mode of conversion of a subdued landscape into a deeply dissected one is the propagation of upstream-migrating erosion waves that transmit the signal of uplift and base level lowering across entire landscapes. Following a shift in tectonic forcing, the Earth's surface progressively adjusts its topographic form over millions of years, seeking to re-establish equilibrium with the new forcing. Here, we show that a high degree of weathering leading to smaller average soil grains at the surface hinders the capacity of rivers to incise. We show that globally, rates of cosmogenic nuclide-derived denudation rates fall into latitudinal belts with (1) low rates of denudation in areas with high temperatures and high precipitation where rock fragments do not persist at the soil surface, (2) high rates of denudation at mid-latitudes where rock fragments exist and are carried efficiently by the river flow, and (3) low rates of denudation at high latitudes where large grains at the surface inhibit channelized flow. We hypothesize that climate sets the pace for landscape change through a balance between slope and grain size. This process acts as a governor on flux of weathering products to the oceans.

Constraints on sediment transfer from the Andes to the coast of northern Chile

NASA Astrophysics Data System (ADS)

Binnie, Steven; Liermann, Ariane; Dunai, Tibor; Dewald, Alfred; Heinze, Stefan

2013-04-01

While rates of denudation have been suggested as having the potential to link tectonic processes with climate in many settings, the roles that sediment transport must also play have been largely neglected. It is the transport, or not, of eroded material, not necessarily the rate at which that material is produced which is the critical factor in many models of tectonic-climatic interactions. The notable lack of sediment in sections of the Peru-Chile trench has been implicated as a key control of subduction zone processes and consequently Andean mountain building, but little empirical data on sediment transport in the region exists. Here, we present the initial results of a study aiming to constrain the westward transfer of sediment from the Andes Mountains to the Pacific Coast of northern Chile by using in situ-produced cosmogenic nuclides. Fluvial sediments were collected at the mouths of several large catchments between 19° S and 26° S, where they drain into the Pacific, and also from upstream locations within each catchment. Sample sites were selected in order to investigate the cosmogenic nuclide derived basin-averaged denudation rates of the western flank of the Andes, and to compare this with the cosmogenic nuclide concentrations of fluvial sediments further downstream where the catchments exit to the coast. A simplistic interpretation of the cosmogenic 10Be concentrations as denudation rates gives results varying between ~10 and 300 m/Myr. We would expect the most rapid erosion to occur on the steeper, wetter western Andean flank and for slower erosion to be recorded from the more gentle sloping, hyperarid/arid regions between the foothills of the Andes and the Pacific coast. This pattern is observed in some basins but in others the nuclide concentrations imply the opposite, with several-fold higher erosion rates measured for the large catchments sampled at the coast in comparison to their mountainous Andean headwaters. One explanation for this unusual pattern of rates is that during travel downstream the modern alluvium is being amalgamated with previously stored sediments that have lost 10Be by decay, thus lowering the average nuclide concentration and artificially inflating apparent erosion rates. The partner cosmogenic 26Al concentrations for the above 10Be results are pending and will also be presented. The differential decay between these two radionuclides after burial allows us to test the above explanation and constrain the potential mixing ratios of stored and non-stored sediments. In turn these results can be used to identify sources for the sediments currently being transported offshore. Potential lag-times between sediment generation and offshore deposition after transport across, or storage in, the hyperarid desert regions could complicate the cause and effect relationships proposed to exist between climate, erosion and mountain building in this region. Mechanisms controlling sediment routing thus become a key variable.

Year-round records of sea salt, gaseous, and particulate inorganic bromine in the atmospheric boundary layer at coastal (Dumont d'Urville) and central (Concordia) East Antarctic sites

NASA Astrophysics Data System (ADS)

Legrand, Michel; Yang, Xin; Preunkert, Susanne; Theys, Nicolas

2016-01-01

Multiple year-round records of bulk and size-segregated compositions of aerosol were obtained at the coastal Dumont d'Urville (DDU) and inland Concordia sites located in East Antarctica. They document the sea-salt aerosol load and composition including, for the first time in Antarctica, the bromide depletion of sea-salt aerosol relative to sodium with respect to seawater. In parallel, measurements of bromide trapped in mist chambers and denuder tubes were done to investigate the concentrations of gaseous inorganic bromine species. These data are compared to simulations done with an off-line chemistry transport model, coupled with a full tropospheric bromine chemistry scheme and a process-based sea-salt production module that includes both sea-ice-sourced and open-ocean-sourced aerosol emissions. Observed and simulated sea-salt concentrations sometime differ by up to a factor of 2 to 3, particularly at DDU possibly due to local wind pattern. In spite of these discrepancies, both at coastal and inland Antarctica, the dominance of sea-ice-related processes with respect to open ocean emissions for the sea-salt aerosol load in winter is confirmed. For summer, observations and simulations point out sea salt as the main source of gaseous inorganic bromine species. Investigations of bromide in snow pit samples do not support the importance of snowpack bromine emissions over the Antarctic Plateau. To evaluate the overall importance of the bromine chemistry over East Antarctica, BrO simulations were also discussed with respect data derived from GOME-2 satellite observations over Antarctica.

Coatings for directional eutectics

NASA Technical Reports Server (NTRS)

Rairden, J. R.; Jackson, M. R.

1976-01-01

Coatings developed to provide oxidation protection for the directionally-solidified eutectic alloy NiTaC-B (4.4 weight percent Cr) were evaluated. Of seven Co-, Fe- and Ni-base coatings that were initially investigated, best resistance to cyclic oxidation was demonstrated by duplex coatings fabricated by depositing a layer of NiCrAl(Y) by vacuum evaporation from an electron beam source followed by deposition of an Al overlayer using the pack cementation process. It was found that addition of carbon to the coating alloy substantially eliminated the problem of fiber denudation in TaC-type eutectic alloys. Burner rig cycled NiTaC-B samples coated with Ni-20Cr-5Al-0.1C-0.1Y+Al and rupture-tested at 1100 deg C performed as well as or better than uncoated, vacuum cycled and air-tested NiTaC-13; however, a slight degradation with respect to uncoated material was noted in air-stress rupture tests at 870 deg C for both cycled and uncycled samples.

THE IMPACT OF HUMANS ON CONTINENTAL EROSION AND SEDIMENTATION (Invited)

NASA Astrophysics Data System (ADS)

Wilkinson, B.; McElroy, B.

2009-12-01

Tectonic uplift and erosional denudation of orogenic belts have long been the most important geologic processes that serve to shape continental surfaces, but the rate of geomorphic change resulting from these natural phenomena has now been outstripped by human activities associated with agriculture, construction, and mining. Although humans are now the most important geomorphic agent on the planet’s surface, natural and anthropogenic processes serve to modify quite different parts of the Earth landscape. In order to better understand the impact of humans on continental erosion, we have examined both long-term and short-term data on rates of sediment transfer in response to glacio-fluvial and anthropogenic processes. Phanerozoic rates of subaerial denudation inferred from preserved volumes of sedimentary rock require a mean continental erosion rate on the order of 16 meters per million years (m/My), resulting in the accumulation of about 5 giga-tons of sediment per year (Gt/y). Erosion irregularly increased over the ~542 million year span of Phanerozoic time to a Pliocene value of 81 m/My (~19 Gt/y). Current estimates of large river sediment loads are similar to this late Neogene value, and require net denudation of ice-free land surfaces at a rate of about 74 m/My (~25 Gt/y). Consideration of variation in large river sediment loads and the geomorphology of respective river basin catchments suggests that natural erosion is primarily confined to drainage headwaters; ~83% of the global river sediment flux is derived from the highest 10% of the Earth’s surface. Subaerial erosion as a result of human activity, primarily through agricultural practices, has resulted in a sharp increase in net rates of continental denudation; although less well constrained than estimates based on surviving rock volumes or current river loads, available data suggest that present farmland denudation is proceeding at a rate of about 600 m/My (~74 Gt/y), and is largely confined to lower elevations of the Earth’s land surface, primarily along passive continental margins; ~83% of cropland erosion occurs over the lower 65% of the Earth’s surface. The conspicuous disparity between natural sediment fluxes suggested by data on rock volumes and river loads (~25 Gt/y) and anthropogenic fluxes inferred from measured and modeled cropland soil losses (74 Gt/y) is readily resolved by data on thicknesses and ages of alluvial sediment that has been deposited immediately down slope from eroding croplands over the history of human agriculture. Accumulation of post-settlement alluvium on higher order tributary channels and floodplains (mean rate ~12,600 m/My) is the most important geomorphic process in terms of the erosion and deposition of sediment that is currently shaping the landscape of the Earth. It far exceeds even the impact of Pleistocene continental glaciers or the current impact of alpine erosion by glacial and/or fluvial processes. Human beings are therefore the dominant agent of topographic change operating on the surface of the planet today.

Soot Particle Studies - Instrument Inter-Comparison – Project Overview

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cross, E.; Sedlacek, A.; Onasch, T. B.

2010-03-06

An inter-comparison study of instruments designed to measure the microphysical and optical properties of soot particles was completed. The following mass-based instruments were tested: Couette Centrifugal Particle Mass Analyzer (CPMA), Time-of-Flight Aerosol Mass Spectrometer - Scanning Mobility Particle Sizer (AMS-SMPS), Single Particle Soot Photometer (SP2), Soot Particle-Aerosol Mass Spectrometer (SP-AMS) and Photoelectric Aerosol Sensor (PAS2000CE). Optical instruments measured absorption (photoacoustic, interferometric, and filter-based), scattering (in situ), and extinction (light attenuation within an optical cavity). The study covered an experimental matrix consisting of 318 runs that systematically tested the performance of instruments across a range of parameters including: fuel equivalence ratiomore » (1.8 {le} {phi} {le} 5), particle shape (mass-mobility exponent (D{sub f m}), 2.0 {le} D{sub f m} {le} 3.0), particle mobility size (30 {le} d{sub m} {le} 300 nm), black carbon mass (0.07 {le} m{sub BC} {le} 4.2 fg) and particle chemical composition. In selected runs, particles were coated with sulfuric acid or dioctyl sebacate (DOS) (0.5 {le} {Delta}r{sub ve} {le} 201 nm) where {Delta}r{sub ve} is the change in the volume equivalent radius due to the coating material. The effect of non-absorbing coatings on instrument response was determined. Changes in the morphology of fractal soot particles were monitored during coating and denuding processes and the effect of particle shape on instrument response was determined. The combination of optical and mass based measurements was used to determine the mass specific absorption coefficient for denuded soot particles. The single scattering albedo of the particles was also measured. An overview of the experiments and sample results are presented.« less

Aerosol-chamber study of the α-pinene/O 3 reaction: influence of particle acidity on aerosol yields and products

NASA Astrophysics Data System (ADS)

Iinuma, Yoshiteru; Böge, Olaf; Gnauk, Thomas; Herrmann, Hartmut

α-Pinene ozonolysis was carried out in the presence of ammonium sulfate or sulfuric acid seed particles in a 9 m 3 Teflon chamber at the mixing ratios of 100 ppbv for α-pinene and about 70 ppbv for ozone. The evolution of size distribution was measured by means of a differential mobility particle sizer (DMPS). The resulting secondary organic aerosol (SOA) was sampled by a denuder/quartz fiber filter combination for the determination of the total organic carbon concentration (TOC) in the particle phase, using a thermographic method and by a denuder/PTFE filter combination for the analysis of individual chemical species in the particle phase using capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS). cis-Pinic acid ( m/ z 185) and another species tentatively identified at m/ z 171 and 199 were the major particle phase species for both seed particles although the product yields were different, indicating the influence of seed particle acidity. A thermographic method for the determination of TOC showed an increase of particle phase organics by 40% for the experiments with higher acidity. CE-ESI-MS analysis showed a large increase in the concentration of compounds with Mw>300 from the experiments with sulfuric acid seed particles. These results suggest that the seed particle acidity enhances the yield of SOA and plays an important role in the formation of larger molecules in the particle phase. Our results from direct particle phase chemical analysis suggest for the first time that condensation of smaller organics takes place by polymerization or aldol condensation following the formation of aldehydes, such as pinonaldehyde from the terpene ozonolysis.

Quantification of Semi-Volatile gas-phase Organic Compounds (SVOCs) & Organic Aerosol species and the role of SVOCs in Secondary Organic Aerosol formation

NASA Astrophysics Data System (ADS)

Khan, M. H.; Holzinger, R.

2013-12-01

A Thermal-Desorption Proton-Transfer-Reaction Mass-Spectrometer (TD-PTR-MS) with different sampling systems (multi-stage denuder for gas phase and impact on a collector for aerosol phase) has been deployed in summer 2013 during the Southern Oxidant and Aerosol Study (SOAS) at the SEARCH ground site, Centreville, Alabama for in-situ gas phase and aerosol measurements on an hourly time resolution. A bunch of DB-1 column (0.53 mm x 5.0 μm) is used in the denuder for capturing the bulk of SVOCs and a collection-thermal-desorption (CTD) cell is used for collecting aerosol particles. Several hundreds semivolatile organic compounds (SVOCs) in gas phase and aerosol phases have been detected. The high mass resolution capabilities of ~5000, low detection limit (<0.05 pptv for gas species, <0.01 ng m-3 for aerosol species) and good physical and chemical characterization of SVOCs with the TD-PTR-MS allows constraining both, the quantity and the chemical composition. The SEARCH site was highly impacted by Biogenic Volatile Organic Compounds (BVOCs) and occasionally influenced by anthropogenic pollution. BVOCs and their oxidation products are capable of partitioning into the particle phase, so their simultaneous quantification in both phases has been used to determine the gas/particle-phase partitioning. Our results show the expected diurnal variation based on the changes of air temperature for many species. The results from this study give valuable insights into sources and processing of Secondary Organic Aerosols (SOAs) that can be used to improve parameterization algorithms in regional and global climate models.

Emergency revegetation to rehabilitate burned watersheds in southern California

Treesearch

Edward S. Corbett; Lisle R. Green

1965-01-01

Reports 4-year results of revegetation measures tested for emergency erosion control after fire denuded the San Dimas Experimental Forest in 1960, including establishment of seeded grasses and their influence on recovery of native vegetation.

Controlling erosion along highways with vegetation or other protective cover.

DOT National Transportation Integrated Search

1976-01-01

Construction operations in highway corridors disturb the natural vegetation and land contours causing potential erosion sites if left denuded. Minimizing erosion on these areas is based on the principles of maximizing water infiltration and reducing ...

Compositional variation in aging volcanic plumes - Analysis of gaseous SO2, CO2 and halogen species in volcanic emissions using an Unmanned Aerial Vehicle (UAV).

NASA Astrophysics Data System (ADS)

Rüdiger, Julian; Lukas, Tirpitz; Bobrowski, Nicole; Gutmann, Alexandra; Liotta, Marcello; de Moor, Maarten; Hoffmann, Thorsten

2017-04-01

Volcanoes are a large source for several reactive atmospheric trace gases including sulfur and halogen containing species. The detailed understanding of volcanic plume chemistry is needed to draw information from gas measurements on subsurface processes. This knowledge is essential for using gas measurements as a monitoring tool for volcanic activity. The reactive bromine species bromine monoxide (BrO) is of particular interest, because BrO as well as SO2 are readily measurable from safe distance by spectroscopic remote sensing techniques. BrO is not directly emitted, but is formed in the plume by a multiphase reaction mechanism. The abundance of BrO changes as a function of the distance from the vent as well as the spatial position in the plume. The precursor substance for the formation of BrO is HBr with Br2as an intermediate product. In this study we present the application of a UAV as a carrier for a remote-controlled sampling system for halogen species (Br2, HBr, BrCl, etc), based on the gas diffusion denuder technique, which allows speciation and enrichment by selective organic reactions. For the analysis of gaseous SO2 and CO2 an in-situ gas monitoring system was additionally mounted. This setup was deployed into the gas plumes of Stromboli Volcano (Italy), Masaya Volcano (Nicaragua) and Turrialba Volcano (Costa Rica) in 2016, to investigate the halogen chemistry at distant locations in the plume further downwind to the emission source, which are in most cases not accessible by other approaches. Flights into the plume were conducted with ascents of up to 1000 m. From telemetrically transmitted SO2 mixing ratios, areas of dense plume where localized to keep the UAV stationary for up to 10 minutes of sampling time. Additionally, ground based samples were taken at the crater rim (at Masaya and Turrialba) using alkaline traps, denuder and gas sensors for comparison with airborne-collected data. Herein we will present time and spatial resolved gas mixing ratio data for SO2, CO2 and halogen species for crater rim sites and a downwind plume age of about 3 to 5 minutes.

[The inhibitive effect produced by local perfusion of tanshinone IIA nanoparticle on neointimal hyperplasia of rabbit carotid artery following intimal denudation].

PubMed

Liang, Ling; Chen, Yucheng; Xiong, Subin; Zeng, Zhi; Sun, Mingliang; Zhang, Haihong

2007-08-01

Tanshinone IIA nanoparticles were constructed and perfused in rabbit's right carotid after intimal denudation with ballon. Localization and retention at different time points of the coumarin-labeled drug nanoparticles were evaluated under laser confocal microscope. Nanoparticles were seen in the three layers of the cross-section artery. At 7 days, they were mainly deposited in the medial layer, while the deposition was generally observed in the adventitia and media at 14 days and 28 days. In the Tanshinone IIA nanoparticle study, a significant reduction of the neo-intimal hyperplasia was noted by comparing the intimal area and the intima-media ratio in the three groups. And the PLGA nanoparticles appeared to be fully biocompatible. As a result, the local administration of the nanoparticles with incorporated Tanshinone IIA showed not only the preventive effects, but aslo the high absorption and good biocompatability in the whole arterial wall.

Yardang evolution from maturity to demise

NASA Astrophysics Data System (ADS)

Barchyn, Thomas E.; Hugenholtz, Chris H.

2015-07-01

Yardangs are enigmatic wind-parallel ridges sculpted by aeolian processes that are found extensively in arid environments on Earth and Mars. No general theory exists to explain the long-term evolution of yardangs, curtailing modeling of landscape evolution and dynamics of suspended sediment release. We present a hypothesis of yardang evolution using relative rates of sediment flux, interyardang corridor downcutting, yardang denudation, substrate erodibility, and substrate clast content. To develop and sustain yardangs, corridor downcutting must exceed yardang vertical denudation and deflation. However, erosion of substrate yields considerable quantities of sediment that shelters corridors, slowing downcutting. We model the evolution of yardangs through various combinations of rates and substrate compositions, demonstrating the life span, suspended sediment release, and resulting landscape evolution. We find that yardangs have a distinct and predictable evolution, with inevitable demise and unexpectedly dynamic and autogenic erosion rates driven by subtle differences in substrate clast composition.

Successful immunosuppressant-free heterotopic transplantation of tracheal allografts in the pig.

PubMed

De Wolf, Julien; Brieu, Mathias; Zawadzki, Christophe; Ung, Alexandre; Kipnis, Eric; Jashari, Ramadan; Hubert, Thomas; Fayoux, Pierre; Mariette, Christophe; Copin, Marie-Christine; Wurtz, Alain

2017-08-01

It has been demonstrated that both heterotopic and orthotopic transplants of epithelium-denuded cryopreserved tracheal allografts are feasible in immunosuppressant-free rabbits. Validation of these results in large animals is required before considering clinical applications. We evaluated the viability, immune tolerance and strain properties of such tracheal allografts heterotopically transplanted in a pig model. Ten tracheal segments, 5 short (5 rings) and 5 long (10 rings), were obtained from male Landrace pigs. The tracheal segments were surgically denuded of their epithelium, then cryopreserved and stored in a tissue bank for 33 to 232 days. After thawing, tracheal segments stented with a silicone tube were wrapped in the omentum in 2 groups of 5 female recipients. The animals did not receive any immunosuppressive drugs. The animals were euthanized from Day 6 to Day 90 in both groups. An effective revascularization of allografts regardless of length was observed. Lymphocyte infiltrate was shown in the early postoperative period and became non-significant after 30 days. Allografts displayed high levels of neoangiogenesis and viable cartilage rings with islets of calcification. Biomechanical measurements demonstrated strain properties similar to those of a fresh tracheal segment from Day 58. Our results demonstrate the acceptability and satisfactory stiffness of epithelium-denuded cryopreserved tracheal allografts implanted in the omentum, despite the absence of immunosuppressive drugs. Since the omentum has the capability to reach the tracheal region, this approach should be investigated in the setting of orthotopic transplants in a pig model before considering clinical applications. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Does Jatropha curcas L. show resistance to drought in the Sahelian zone of West Africa? A case study from Burkina Faso

NASA Astrophysics Data System (ADS)

Bayen, P.; Sop, T. K.; Lykke, A. M.; Thiombiano, A.

2015-05-01

Land degradation is an environmental problem which weakens agro-sylvo-pastoral productivity in sub-Saharan Africa. The most common manifestation of land degradation is the appearance of denuded land. We carried out an experiment to test the effect of three soil and water conservation techniques on survival and growth of Jatropha curcas seedlings transplanted onto two completely denuded lands in the Sahelian and Sudanian zones of Burkina Faso. We implemented an experimental design with three replicates per restoration technique. A total of 174 seedlings were planted in each study site. The results showed that the soil water content varied according to the restoration technique used (df = 2; F = 53.21; p < 0.00) as well as according to study site (df = 1; F = 74.48; p < 0.00). Soil water content was significantly lower in the Sahel than in the Sudanian zone. Seedling survival rate varied significantly according to technique used (df = 2; F = 8.91; p = 0.000) and study site (df = 1; F = 9.74; p = 0.003). Survival rate, diameter and seedling height were highest at the Sudanian site. At the Sahelian site, all seedlings died 2 years after establishment. These results suggest that J. curcas is unsuited to denuded land in the Sahelian zone. Most of the plants died in the Sahel between April and May, which is the peak of the dry season; this may be an indication that J. curcas may not be as drought-resistant as suggested by the prolific literature which has reported on diverse claims surrounding this plant.

Does Jatropha curcas L. show resistance to drought in the Sahelian zone of West Africa? A case study from Burkina Faso

NASA Astrophysics Data System (ADS)

Bayen, P.; Sop, T. K.; Lykke, A. M.; Thiombiano, A.

2015-02-01

Land degradation is an environmental problem which weakens agro-silvo-pastoral productivity in Sub-Saharan Africa. The most common manifestation of land degradation is the appearance of denuded land. We carried out an experiment to test the effect of three soil and water conservation techniques on survival and growth of Jatropha curcas seedlings transplanted onto two completely denuded lands in the Sahelian and Sudanian zones of Burkina Faso. We implemented an experimental design with three replicates per restoration technique. A total of 174 seedlings were planted in each study site. The results showed that soil water content varied according to the restoration technique used (df = 2; F = 53.21; p < 0.00) as well as according to study site (df = 1; F = 74.48; p < 0.00). Soil water content was significantly lower in the Sahel than in the Sudanian zone. Seedling survival rate varied significantly according to technique used (df = 2; F = 8.91; p = 0.000) and study site (df = 1; F = 9.74; p = 0.003). Survival rate, diameter and seedling height were highest at the Sudanian site. At the Sahelian site, all seedlings died two years after establishment. These results suggest that Jatropha curcas is unsuited to denuded land in the Sahelian zone. Most of the plants died in the Sahel between April and May, which is the peak of the dry season; this may be an indication that Jatropha may not be as drought-resistant as suggested by the prolific literature which has reported on diverse claims surrounding this plant.

Hirudin (desulfated, 54-65) contracts canine coronary arteries: extracellular calcium influx mediates hirudin-induced contractions.

PubMed

Sorajja, Paul; Cable, David G; Hamner, Chad E; Schaff, Hartzell V

2004-09-01

Although the anticoagulatory properties of hirudin are well known, its direct vasoactive effects have not been investigated extensively. Hirudin stimulates nitric oxide and prostacyclin production in noncoronary vascular beds, but its actions on coronary arteries are unknown. Five-millimeter segments of canine left circumflex coronary arteries were obtained for organ chamber experiments. Some segments were denuded of endothelium before study. Segments were exposed to hirudin (10(-10)-10(-6) mol/L) following precontraction with prostaglandin F(2alpha) with or without pretreatment with indomethacin or calcium channel blockers (verapamil and nifedipine). Hirudin stimulated endothelium-independent contraction in coronary arterial segments. Maximum tension (hirudin 10(-6) mol/L) above precontraction baseline was 33.6 +/- 9.0% (n = 10, P < 0.05) for endothelium-intact and 31.8 +/- 11.5% (n = 8, P < 0.05) for endothelium-denuded arterial segments. Differences between endothelium-intact and endothelium-denuded segments were not significant. Contractile responses to hirudin were unaffected by the presence of indomethacin. Pretreatment with either verapamil or nifedipine (10(-4) mol/L) for 1 h attenuated these contractions. The maximal increase in tension above baseline (hirudin 10(-6) mol/L) for verapamil and nifedipine was only 6.2 +/- 12.4 and 3.8 +/- 7.0% (n = 6, P < 0.05 versus endothelium-intact control), respectively. Hirudin stimulates endothelium-independent contractions of canine coronary arteries in vitro. Pretreatment with calcium channel blockers attenuates this response, suggesting that extracellular influx of calcium has an important mechanistic role in hirudin-mediated coronary artery constriction.

Multiple factors affect a population of Agassiz's desert tortoise (Gopherus agassizii) in the Northwestern Mojave Desert

USGS Publications Warehouse

Berry, Kristin H.; Yee, Julie L.; Coble, Ashley A.; Perry, William M.; Shields, Timothy A.

2013-01-01

Numerous factors have contributed to declines in populations of the federally threatened Agassiz's Desert Tortoise (Gopherus agassizii) and continue to limit recovery. In 2010, we surveyed a low-density population on a military test facility in the northwestern Mojave Desert of California, USA, to evaluate population status and identify potential factors contributing to distribution and low densities. Estimated densities of live tortoises ranged spatially from 1.2/km2 to 15.1/km2. Although only one death of a breeding-age tortoise was recorded for the 4-yr period prior to the survey, remains of 16 juvenile and immature tortoises were found, and most showed signs of predation by Common Ravens (Corvus corax) and mammals. Predation may have limited recruitment of young tortoises into the adult size classes. To evaluate the relative importance of different types of impacts to tortoises, we developed predictive models for spatially explicit densities of tortoise sign and live tortoises using topography (i.e., slope), predators (Common Raven, signs of mammalian predators), and anthropogenic impacts (distances from paved road and denuded areas, density of ordnance fragments) as covariates. Models suggest that densities of tortoise sign increased with slope and signs of mammalian predators and decreased with Common Ravens, while also varying based on interaction effects involving these predictors as well as distances from paved roads, denuded areas, and ordnance. Similarly, densities of live tortoises varied by interaction effects among distances to denuded areas and paved roads, density of ordnance fragments, and slope. Thus multiple factors predict the densities and distribution of this population.

Rhetoric Denuded and Redressed: Figs and Figures.

ERIC Educational Resources Information Center

Poulakos, John; Whitson, Steve

1995-01-01

Replies to an article in this issue that responds to an earlier article by these authors. Replies aesthetically in aphorisms, subsuming philosophical argument within a vortex of figuration and thus troping the knowledge drive while privileging "doxa" over "episteme." (SR)

The parietal epithelial cell: a key player in the pathogenesis of focal segmental glomerulosclerosis in Thy-1.1 transgenic mice.

PubMed

Smeets, Bart; Te Loeke, Nathalie A J M; Dijkman, Henry B P M; Steenbergen, Mark L M; Lensen, Joost F M; Begieneman, Mark P V; van Kuppevelt, Toin H; Wetzels, Jack F M; Steenbergen, Eric J

2004-04-01

Focal segmental glomerulosclerosis (FSGS) is a hallmark of progressive renal disease. Podocyte injury and loss have been proposed as the critical events that lead to FSGS. In the present study, the authors have examined the development of FSGS in Thy-1.1 transgenic (tg) mice, with emphasis on the podocyte and parietal epithelial cell (PEC). Thy-1.1 tg mice express the Thy-1.1 antigen on podocytes. Injection of anti-Thy-1.1 mAb induces an acute albuminuria and development of FSGS lesions that resemble human collapsing FSGS. The authors studied FSGS lesions at days 1, 3, 6, 7, 10, 14, and 21, in relation to changes in the expression of specific markers for normal podocytes (WT-1, synaptopodin, ASD33, and the Thy-1.1 antigen), for mouse PEC (CD10), for activated podocytes (desmin), for macrophages (CD68), and for proliferation (Ki-67). The composition of the extracellular matrix (ECM) that forms tuft adhesions or scars was studied using mAb against collagen IV alpha2 and alpha4 chains and antibodies directed against different heparan sulfate species. The first change observed was severe PEC injury at day 1, which increased in time, and resulted in denuded segments of Bowman's capsule at days 6 and 7. Podocytes showed foot process effacement and microvillous transformation. There was no evidence of podocyte loss or denudation of the GBM. Podocytes became hypertrophic at day 3, with decreased expression of ASD33 and synaptopodin and normal expression of WT-1 and Thy-1.1. Podocyte bridges were formed by attachment of hypertrophic podocytes to PEC and podocyte apposition against denuded segments of Bowman's capsule. At day 6, there was a marked proliferation of epithelial cells in Bowman's space. These proliferating cells were negative for desmin and all podocyte markers, but stained for CD10, and thus appeared to be PEC. The staining properties of the early adhesions were identical to that of Bowman's capsule, suggesting that the ECM in the adhesions was produced by PEC. In conclusion, the authors propose the following sequence of events leading to FSGS lesions in the Thy1.1 tg mice: (1) PEC damage and denudation of Bowman's capsule segments; (2) podocyte hypertrophy and bridging; and (3) PEC proliferation with ECM production.

Surface Evolution and Uplift History of the Central Apennines, Italy: New Constraints from Thermochronology and Paleoaltimetry

NASA Astrophysics Data System (ADS)

San José, M.; Faccenna, C.; Fellin, M. G.; Willett, S.; Funiciello, F.; Caves Rugenstein, J. K.

2017-12-01

The topography of mountain belts results from interactions between surface processes, lithospheric thickening, and mantle dynamics. However, the contributions of each mechanism have yet to be clearly quantified. The Apennines (Italy) provide a study area where all of these processes are at play. The central part of the Apennines is an orogenic wedge formed by the westward subducting Adriatic microplate during Miocene-Pliocene, and overlies an area of local slab detachment. Recent studies indicate anomalously high uplift rates in this area (Faccenna et al., 2015), as well as a simultaneous onset of post-orogenic extension across the Central Apennines at ̴ 2 Ma (Cosentino et al., 2017). These observations have been interpreted as an expression of dynamic topography due to the slab break-off and inherent mantle upwelling. In order to test this hypothesis and further constrain the topographic evolution of the orogen, we use low-temperature thermochronology to date the exhumation, and stable isotope paleoaltimetry (18O/16O on carbonates) to reconstruct paleoelevations. We couple this paleotopographic dataset with geomorphological analysis of the present day topography. Here we present a set of 30 new (U-Th)/He cooling ages on apatites (AHe) sampled from widespread syn-orogenic flysch basin deposits (including one high-resolution vertical profile), as well as preliminary isotopic measurements. Initial results show mean AHe ages ranging from 1.62 (± 0.38 ) Ma to 2.6 (±0.02) Ma, suggesting a regionally uniform exhumation during Pleistocene. Denudation rates inferred from our vertical profile are extremely high (>1 mm/year from 2 to 1 Ma). Some samples have not been thermally reset due to insufficient burial, and yield exhumation ages older than stratigraphic depositional ages (generally > 5 Ma). These results support the hypothesis that exhumation is mainly controlled by rapid regional scale uplift related to the opening of the Adriatic slab window at the end of the orogenic phase. However, denudation is not only driven by geodynamic processes, but also by climatic changes. Further research will consider climatic variations in the interpretation of our results.

Isotopic geochemistry of Panama rivers

USGS Publications Warehouse

Harmon, Russell S.; Worner, Gerhard; Pribil, Michael; Kern, Zoltan; Forizs, Istvan; Lyons, W. Berry; Gardner, Christopher B.; Goldsmith, Steven T.

2015-01-01

River water samples collected from 78 watersheds rivers along a 500-km transect across a Late Cretaceous-Tertiary andesitic volcanic arc terrane in west-central Panama provide a synoptic overview of riverine geochemistry, chemical denudation, and CO2 consumption in the tropics. D/H and 18O/16O relationships indicate that bedrock dissolution of andesitic arc crust in Panama is driven by water-rock interaction with meteoric precipitation as it passes through the critical zone, with no evidence of a geothermal or hydrothermal input. Sr-isotope relationships suggest a geochemical evolution for Panama riverine waters that involves mixing of bedrock pore water with water having 87Sr/86Sr ratios between 0.7037-0.7043 and relatively high Sr-contents with waters of low Sr content that enriched in radiogenic Sr that are diluted by infiltrating rainfall to variable extents.

Catchment-wide weathering and erosion rates of mafic, ultramafic, and granitic rock from cosmogenic meteoric 10Be/9Be ratios

NASA Astrophysics Data System (ADS)

Dannhaus, N.; Wittmann, H.; Krám, P.; Christl, M.; von Blanckenburg, F.

2018-02-01

Quantifying rates of weathering and erosion of mafic rocks is essential for estimating changes to the oceans alkalinity budget that plays a significant role in regulating atmospheric CO2 levels. In this study, we present catchment-wide rates of weathering, erosion, and denudation measured with cosmogenic nuclides in mafic and ultramafic rock. We use the ratio of the meteoric cosmogenic nuclide 10Be, deposited from the atmosphere onto the weathering zone, to stable 9Be, a trace metal released by silicate weathering. We tested this approach in stream sediment and water from three upland forested catchments in the north-west Czech Republic. The catchments are underlain by felsic (granite), mafic (amphibolite) and ultramafic (serpentinite) lithologies. Due to acid rain deposition in the 20th century, the waters in the granite catchment exhibit acidic pH, whereas waters in the mafic catchments exhibit neutral to alkaline pH values due to their acid buffering capability. The atmospheric depositional 10Be flux is estimated to be balanced with the streams' dissolved and particulate meteoric 10Be export flux to within a factor of two. We suggest a correlation method to derive bedrock Be concentrations, required as an input parameter, which are highly heterogeneous in these small catchments. Derived Earth surface metrics comprise (1) Denudation rates calculated from the 10Be/9Be ratio of the "reactive" Be (meaning sorbed to mineral surfaces) range between 110 and 185 t km-2 y-1 (40 and 70 mm ky-1). These rates are similar to denudation rates we obtained from in situ-cosmogenic 10Be in quartz minerals present in the bedrock or in quartz veins in the felsic and the mafic catchment. (2) The degree of weathering, calculated from the fraction of 9Be released from primary minerals as a new proxy, is about 40-50% in the mafic catchments, and 10% in the granitic catchment. Lastly, (3) erosion rates were calculated from 10Be concentrations in river sediment and corrected for sorting and dissolved loss. These amount to 50% of denudation rates from 10Be/9Be in the mafic and ultramafic catchments, the remainder being mass loss in the dissolved form by weathering. In contrast, erosion comprises most of the mass loss in the granitic catchment. These first results are encouraging, given that we find overall good agreement between in situ and meteoric cosmogenic methods, that our denudation rates are in the range of those published for middle European river catchments, and that degrees of weathering are as expected for these diverse lithologies. This method allows quantifying rates of erosion and weathering in mafic rock over the time scale of weathering that are, unlike in situ cosmogenic 10Be, independent from the presence of quartz. 10Be/9Be therefore offers to quantify Earth surface processes in a wide range of landscapes underlain by mafic rock - rates that are of high importance for exploring climate-weathering feedbacks but that have been inaccessible to date.

Structural changes in the human vas deferens after tantalum clip occlusion and conventional vasectomy.

PubMed

Kothari, L K; Gupta, A S

1978-02-01

In 15 human subjects, the vasa deferentia were occluded by applying two tantalum clips on one side and by conventional vasectomy with silk ligatures on the other. After 2 weeks, the occluded segments were recovered for histopathologic examination of serial sections. Obstructing the seminal tract did not, as such, produce any significant change in the vas: the distal and proximal segments appeared to be essentially similar and normal. At the actual site of occlusion, however, tantalum clips produced marked flattening of the tube, complete loss of lining epithelium, distortion of the muscular lamellae, and areas of hemorrhage. The lumen was converted into a narrow slit. Under the ligatures, the damage was largely confined to denudation of the mucosal epithelium. The mucosa of the intersegment left unexcised between two clips showed hyalinization, invasion by macrophages, and degeneration of the epithelium. The changes under the clips suggest that, although clip occlusion may offer several advantages, sterility cannot be reversed merely by removing the clips. The mechanisms of these changes, different in the case of clips and ligatures, are discussed and some possible long-term consequences are considered.

Decreased Neointimal Extracellular Matrix Formation in RAGE-Knockout Mice After Microvascular Denudation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Groezinger, Gerd, E-mail: gerd.groezinger@med.uni-tuebingen.de; Schmehl, Joerg, E-mail: joerg.schmehl@med.uni-tuebingen.de; Bantleon, Ruediger, E-mail: ruediger.bantleon@med.uni-tuebingen.de

2012-12-15

Purpose: To evaluate in vivo the role of RAGE (receptor for advanced glycated end products) in the development of restenosis and neointimal proliferation in RAGE-deficient knockout (KO) mice compared with wild-type (WT) mice in an animal model. Materials and Methods: Sixteen WT and 15 RAGE-deficient mice underwent microvascular denudation of the common femoral artery under general anaesthesia. Contralateral arteries underwent a sham operation and served as controls. Four weeks after the intervention, all animals were killed, and paraformaldehyde-fixed specimens of the femoral artery were analysed with different stains (hematoxylin and eosin and Elastica van Gieson) and several different types ofmore » immunostaining (proliferating cell nuclear antigen, {alpha}-actin, collagen, von Willebrand factor, RAGE). Luminal area, area of the neointima, and area of the media were measured in all specimens. In addition, colony-formation assays were performed, and collagen production by WT smooth muscle cells (SMCs) and RAGE-KO SMCs was determined. For statistical analysis, P < 0.05 was considered statistically significant. Results: Four weeks after denudation, WT mice showed a 49.6% loss of luminal area compared with 14.9% loss of luminal area in RAGE-deficient mice (sham = 0% loss) (P < 0.001). The neointima was 18.2 (*1000 {mu}m{sup 2} [n = 15) in the WT group compared with only 8.4 (*1000 {mu}m{sup 2} [n = 16]) in the RAGE-KO group. RAGE-KO SMCs showed significantly decreased proliferation activity and production of extracellular matrix protein. Conclusion: RAGE may be shown to play a considerable role in the formation of neointima leading to restenosis after vascular injury.« less

Role of inducible nitric oxide synthase in endothelium‐independent relaxation to raloxifene in rat aorta

PubMed Central

Au, Chak Leung; Tsang, Suk Ying; Lau, Chi Wai; Yao, Xiaoqiang; Cai, Zongwei

2017-01-01

Background and Purpose Raloxifene can induce both endothelium‐dependent and ‐independent relaxation in different arteries. However, the underlying mechanisms by which raloxifene triggers endothelium‐independent relaxation are still incompletely understood. The purpose of present study was to examine the roles of NOSs and Ca2+ channels in the relaxant response to raloxifene in the rat isolated, endothelium‐denuded aorta. Experimental Approach Changes in isometric tension, cGMP, nitrite, inducible NOS protein expression and distribution in response to raloxifene in endothelium‐denuded aortic rings were studied by organ baths, radioimmunoassay, Griess reaction, western blot and immunohistochemistry respectively. Key Results Raloxifene reduced the contraction to CaCl2 in a Ca2+‐free, high K+‐containing solution in intact aortic rings. Raloxifene also acutely relaxed the aorta primarily through an endothelium‐independent mechanism involving NO, mostly from inducible NOS (iNOS) in vascular smooth muscle layers. This effect of raloxifene involved the generation of cGMP and nitrite. Also, it was genomic in nature, as it was inhibited by a classical oestrogen receptor antagonist and inhibitors of RNA and protein synthesis. Raloxifene‐induced stimulation of iNOS gene expression was partly mediated through activation of the NF‐κB pathway. Raloxifene was more potent than 17β‐estradiol or tamoxifen at relaxing endothelium‐denuded aortic rings by stimulation of iNOS. Conclusions and Implications Raloxifene‐mediated vasorelaxation in rat aorta is independent of a functional endothelium and is mediated by oestrogen receptors and NF‐κB. This effect is mainly mediated through an enhanced production of NO, cGMP and nitrite, via the induction of iNOS and inhibition of calcium influx through Ca2+ channels in rat aortic smooth muscle. PMID:28138957

Vitrification of zona-free rabbit expanded or hatching blastocysts: a possible model for human blastocysts.

PubMed

Cervera, R P; Garcia-Ximénez, F

2003-10-01

The purpose of this study was to test the effectiveness of one two-step (A) and two one-step (B1 and B2) vitrification procedures on denuded expanded or hatching rabbit blastocysts held in standard sealed plastic straws as a possible model for human blastocysts. The effect of blastocyst size was also studied on the basis of three size categories (I: diameter <200 micro m; II: diameter 200-299 micro m; III: diameter >/==" BORDER="0">300 micro m). Rabbit expanded or hatching blastocysts were vitrified at day 4 or 5. Before vitrification, the zona pellucida was removed using acidic phosphate buffered saline. For the two-step procedure, prior to vitrification, blastocysts were pre- equilibrated in a solution containing 10% dimethyl sulphoxide (DMSO) and 10% ethylene glycol (EG) for 1 min. Different final vitrification solutions were compared: 20% DMSO and 20% EG with (A and B1) or without (B2) 0.5 mol/l sucrose. Of 198 vitrified blastocysts, 181 (91%) survived, regardless of the vitrification procedure applied. Vitrification procedure A showed significantly higher re-expansion (88%), attachment (86%) and trophectoderm outgrowth (80%) rates than the two one-step vitrification procedures, B1 and B2 (46 and 21%, 20 and 33%, and 18 and 23%, respectively). After warming, blastocysts of greater size (II and III) showed significantly higher attachment (54 and 64%) and trophectoderm outgrowth (44 and 58%) rates than smaller blastocysts (I, attachment: 29%; trophectoderm outgrowth: 25%). These result demonstrate that denuded expanded or hatching rabbit blastocysts of greater size can be satisfactorily vitrified by use of a two-step procedure. The similarity of vitrification solutions used in humans could make it feasible to test such a procedure on human denuded blastocysts of different sizes.

Cascade Bioassay Evidence for the Existence of Urothelium-Derived Inhibitory Factor in Guinea Pig Urinary Bladder

PubMed Central

Guan, Na N.; Thor, Anna; Hallén, Katarina; Wiklund, N. Peter; Gustafsson, Lars E.

2014-01-01

Our aim was to investigate whether guinea pig urothelium-derived bioactivities compatible with the existence of urothelium-derived inhibitory factor could be demonstrated by in vitro serial bioassay and whether purinergic P1 receptor agonists, nitric oxide, nitrite or prostaglandins might explain observed activities. In a cascade superfusion system, urothelium-denuded guinea pig ureters were used as bioassay tissues, recording their spontaneous rhythmic contractions in presence of scopolamine. Urothelium-intact or -denuded guinea pig urinary bladders were used as donor tissues, stimulated by intermittent application of carbachol before or during the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME), the adenosine/P1 nucleoside receptor antagonist 8-(p-sulfophenyl)theophylline (8-PST) or the cyclo-oxygenase inhibitor diclofenac infused to bath donor and bioassay tissues. The spontaneous contractions of bioassay ureters were unaltered by application of carbachol 1–5 µM in the presence of scopolamine 5–30 µM. When carbachol was applied over the urothelium-denuded bladder, the assay ureter contraction rate was unaltered. Introducing carbachol over the everted urothelium-intact bladder significantly inhibited the contraction frequency of the assay ureter, suggesting the transfer of an inhibitory activity from the bladder to the assay ureter. The transmissible inhibitory activity was not markedly antagonized by L-NAME, 8-PST or diclofenac, while L-NAME nearly abolished nitrite release from the urothelium-intact bladder preparations. We suggest that urothelium-derived inhibitory factor is a transmissible entity over a significant distance as demonstrated in this novel cascade superfusion assay and seems less likely to be nitric oxide, nitrite, an adenosine receptor agonist or subject to inhibition by administration of a cyclo-oxygenase inhibitor. PMID:25084114

Cascade bioassay evidence for the existence of urothelium-derived inhibitory factor in Guinea pig urinary bladder.

PubMed

Guan, Na N; Thor, Anna; Hallén, Katarina; Wiklund, N Peter; Gustafsson, Lars E

2014-01-01

Our aim was to investigate whether guinea pig urothelium-derived bioactivities compatible with the existence of urothelium-derived inhibitory factor could be demonstrated by in vitro serial bioassay and whether purinergic P1 receptor agonists, nitric oxide, nitrite or prostaglandins might explain observed activities. In a cascade superfusion system, urothelium-denuded guinea pig ureters were used as bioassay tissues, recording their spontaneous rhythmic contractions in presence of scopolamine. Urothelium-intact or -denuded guinea pig urinary bladders were used as donor tissues, stimulated by intermittent application of carbachol before or during the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME), the adenosine/P1 nucleoside receptor antagonist 8-(p-sulfophenyl)theophylline (8-PST) or the cyclo-oxygenase inhibitor diclofenac infused to bath donor and bioassay tissues. The spontaneous contractions of bioassay ureters were unaltered by application of carbachol 1-5 µM in the presence of scopolamine 5-30 µM. When carbachol was applied over the urothelium-denuded bladder, the assay ureter contraction rate was unaltered. Introducing carbachol over the everted urothelium-intact bladder significantly inhibited the contraction frequency of the assay ureter, suggesting the transfer of an inhibitory activity from the bladder to the assay ureter. The transmissible inhibitory activity was not markedly antagonized by L-NAME, 8-PST or diclofenac, while L-NAME nearly abolished nitrite release from the urothelium-intact bladder preparations. We suggest that urothelium-derived inhibitory factor is a transmissible entity over a significant distance as demonstrated in this novel cascade superfusion assay and seems less likely to be nitric oxide, nitrite, an adenosine receptor agonist or subject to inhibition by administration of a cyclo-oxygenase inhibitor.

A novel bronchial ring bioassay for the evaluation of small airway smooth muscle function in mice.

PubMed

Liu, John Q; Yang, Dennis; Folz, Rodney J

2006-08-01

Advances in our understanding of murine airway physiology have been hindered by the lack of suitable, ex vivo, small airway bioassay systems. In this study, we introduce a novel small murine airway bioassay system that permits the physiological and pharmacological study of intrapulmonary bronchial smooth muscle via a bronchial ring (BR) preparation utilizing BR segments as small as 200 microm in diameter. Using this ex vivo BR bioassay, we characterized small airway smooth muscle contraction and relaxation in the presence and absence of bronchial epithelium. In control BRs, the application of mechanical stretch is followed by spontaneous bronchial smooth muscle relaxation. BRs pretreated with methacholine (MCh) partially attenuate this stretch-induced relaxation by as much as 42% compared with control. MCh elicited a dose-dependent bronchial constriction with a maximal tension (E(max)) of 8.7 +/- 0.2 mN at an EC(50) of 0.33 +/- 0.02 microM. In the presence of nifedipine, ryanodine, 2-aminoethoxydiphenyl borate, and SKF-96365, E(max) to MCh was significantly reduced. In epithelium-denuded BRs, MCh-induced contraction was significantly enhanced to 11.4 +/- 1.0 mN with an EC(50) of 0.16 +/- 0.04 microM (P < 0.01). Substance P relaxed MCh-precontracted BR by 62.1%; however, this bronchial relaxation effect was completely lost in epithelium-denuded BRs. Papaverine virtually abolished MCh-induced constriction in both epithelium-intact and epithelium-denuded bronchial smooth muscle. In conclusion, this study introduces a novel murine small airway BR bioassay that allows for the physiological study of smooth muscle airway contractile responses that may aid in our understanding of the pathophysiology of asthma.

Mechanisms underlying sodium nitroprusside-induced tolerance in the mouse aorta: Role of ROS and cyclooxygenase-derived prostanoids.

PubMed

Diniz, Mariana C; Olivon, Vania C; Tavares, Lívia D; Simplicio, Janaina A; Gonzaga, Natália A; de Souza, Daniele G; Bendhack, Lusiane M; Tirapelli, Carlos R; Bonaventura, Daniella

2017-05-01

To determine the role of reactive oxygen species (ROS) on sodium nitroprusside (SNP)-induced tolerance. Additionally, we evaluated the role of ROS on NF-κB activation and pro-inflammatory cytokines production during SNP-induced tolerance. To induce in vitro tolerance, endothelium-intact or -denuded aortic rings isolated from male Balb-c mice were incubated for 15, 30, 45 or 60min with SNP (10nmol/L). Tolerance to SNP was observed after incubation of endothelium-denuded, but not endothelium-intact aortas for 60min with this inorganic nitrate. Pre-incubation of denuded rings with tiron (superoxide anion (O 2 - ) scavenger), and the NADPH oxidase inhibitors apocynin and atorvastatin reversed SNP-induced tolerance. l-NAME (non-selective NOS inhibitor) and l-arginine (NOS substrate) also prevented SNP-induced tolerance. Similarly, ibuprofen (non-selective cyclooxygenase (COX) inhibitor), nimesulide (selective COX-2 inhibitor), AH6809 (prostaglandin PGF 2 α receptor antagonist) or SQ29584 [PGH 2 /thromboxane TXA 2 receptor antagonist] reversed SNP-induced tolerance. Increased ROS generation was detected in tolerant arteries and both tiron and atorvastatin reversed this response. Tiron prevented tolerance-induced increase on O 2 - and hydrogen peroxide (H 2 O 2 ) levels. The increase onp65/NF-κB expression and TNF-α production in tolerant arteries was prevented by tiron. The major new finding of our study is that SNP-induced tolerance is mediated by NADPH-oxidase derived ROS and vasoconstrictor prostanoids derived from COX-2, which are capable of reducing the vasorelaxation induced by SNP. Additionally, we found that ROS mediate the activation of NF-κB and the production of TNF-α in tolerant arteries. These findings identify putative molecular mechanisms whereby SNP induces tolerance in the vasculature. Copyright © 2017 Elsevier Inc. All rights reserved.

Endothelial dysfunction impairs vascular neurotransmission in tail arteries.

PubMed

Sousa, Joana B; Fresco, Paula; Diniz, Carmen

2015-01-01

The present study intends to clarify if endothelium dysfunction impairs vascular sympathetic neurotransmission. Electrically-evoked tritium overflow (100 pulses/5 Hz) was evaluated in arteries (intact and denuded) or exhibiting some degree of endothelium dysfunction (spontaneously hypertensive arteries), pre-incubated with [(3)H]-noradrenaline in the presence of enzymes (nitric oxide synthase (NOS); nicotinamide adenine dinucleotide phosphate (NADPH) oxidase; xanthine oxidase; cyclooxygenase; adenosine kinase) inhibitors and a nucleoside transporter inhibitor. Inhibition of endothelial nitric oxide synthase with L-NIO dihydrochloride reduced tritium overflow in intact arteries whereas inhibition of neuronal nitric oxide synthase with Nω-Propyl-L-arginine hydrochloride was devoid of effect showing that only endothelial nitric oxide synthase is involved in vascular sympathetic neuromodulation. Inhibition of enzymes involved in reactive oxygen species or prostaglandins production with apocynin and allopurinol or indomethacin, respectively, failed to alter tritium overflow. A facilitation or reduction of tritium overflow was observed in the presence of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) or of 5-iodotubericidin, respectively, but only in intact arteries. These effects can be ascribed to a tonic inhibitory effect mediated by A1 receptors. In denuded and hypertensive arteries, 7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo[1,5-c] pyrimidine (SCH 58261) reduced tritium overflow, suggesting the occurrence of a tonic activation of A2A receptors. When endogenous adenosine bioavailability was increased by the nucleoside transporter inhibitor, S-(4-Nitrobenzyl)-6-thioinosine, tritium overflow increased in intact, denuded and hypertensive arteries. Among the endothelium-derived substances studied that could alter vascular sympathetic transmission only adenosine/adenosine receptor mediated mechanisms were clearly impaired by endothelium injury/dysfunction. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biphasic effect of Psidium guajava Linn. (Myrtaceae) leaf aqueous extract on rat isolated vascular smooth muscles.

PubMed

Chiwororo, Witness D H; Ojewole, John A O

2008-12-01

In this study, we examined the effects of Psidium guajava Linn. leaf aqueous extract (PGE) on isolated, spontaneously-contracting portal veins, as well as on endothelium-intact and endothelium-denuded descending thoracic aortic ring preparations of healthy, normotensive rats. Graded concentrations of PGE (0.25-4.0 mg/ml) caused concentration-dependent, initial brief but significant (P<0.05) rises of the basal tones and amplitudes of pendular, rhythmic contractions, followed by secondary pronounced, longer-lasting and significant (P<0.05-0.001) inhibitions of contractile amplitudes of the isolated portal veins. Relatively low concentrations of PGE (<1.0 mg/ml) always contracted freshly-mounted, naïve, endothelium-intact aortic ring preparations. However, relatively high concentrations of PGE (1.0-4.0 mg/ml) always produced initial brief contractions/augmentations of noradrenaline (NA, 10(-7)M)-induced contractions of endothelium-intact and endothelium-denuded aortic ring preparations, followed by secondary, pronounced relaxations of the aortic ring muscles. Moreover, relatively high concentrations of PGE (1.0-4.0 mg/kg) always relaxed NA-induced contractions of the aortic ring preparations in a concentration-related manner. The arterial-relaxing effects of PGE were more pronounced in endothelium-intact aortic rings than in endothelium-denuded aortic ring preparations. The relaxant effects of PGE on endothelium-intact aortic rings were only partially inhibited by N(G)-nitro-L-arginine methyl ester (L-NAME, 100 microM), a nitric oxide synthase inhibitor, suggesting that the vasorelaxant effect of PGE on aortic rings is probably mediated via both endothelium-derived relaxing factor (EDRF)-dependent and EDRF-independent mechanisms. Taken together, the findings of this study indicate that PGE possesses a biphasic effect on rat isolated vascular smooth muscles.

Brazilin isolated from the heartwood of Caesalpinia sappan L induces endothelium-dependent and -independent relaxation of rat aortic rings

PubMed Central

Yan, Yu; Chen, Yu-cai; Lin, Yi-huang; Guo, Jing; Niu, Zi-ran; Li, Li; Wang, Shou-bao; Fang, Lian-hua; Du, Guan-hua

2015-01-01

Aim: Brazilin is one of the major constituents of Caesalpinia sappan L with various biological activities. This study sought to investigate the vasorelaxant effect of brazilin on isolated rat thoracic aorta and explore the underlying mechanisms. Methods: Endothelium-intact and -denuded aortic rings were prepared from rats. The tension of the preparations was recorded isometrically with a force displacement transducer connected to a polygraph. The phosphorylation levels of ERK1/2 and myosin light chain (MLC) were analyzed using Western blotting assay. Results: Application of brazilin (10–100 μmol/L) dose-dependently relaxed the NE- or high K+-induced sustained contraction of endothelium-intact aortic rings (the EC50 was 83.51±5.6 and 79.79±4.57 μmol/L, respectively). The vasorelaxant effect of brazilin was significantly attenuated by endothelium removal or by pre-incubation with L-NAME, methylene blue or indomethacin. In addition, pre-incubation with brazilin dose-dependently attenuated the vasoconstriction induced by KCl, NE or Ang II. Pre-incubation with brazilin also markedly suppressed the high K+-induced extracellular Ca2+ influx and NE-induced intracellular Ca2+ release in endothelium-denuded aortic rings. Pre-incubation with brazilin dose-dependently inhibited the NE-stimulated phosphorylation of ERK1/2 and MLC in both endothelium-intact and -denuded aortic rings. Conclusion: Brazilin induces relaxation in rat aortic rings via both endothelium-dependent and -independent ways as well as inhibiting NE-stimulated phosphorylation of ERK1/2 and MLC. Brazilin also attenuates vasoconstriction via blocking voltage- and receptor-operated Ca2+ channels. PMID:26564314

Estrogen Replacement Therapy in Ovariectomized Nonpregnant Ewes Stimulates Uterine Artery Hydrogen Sulfide Biosynthesis by Selectively Up-Regulating Cystathionine β-Synthase Expression

PubMed Central

Lechuga, Thomas J.; Zhang, Hong-hai; Sheibani, Lili; Karim, Muntarin; Jia, Jason; Magness, Ronald R.; Rosenfeld, Charles R.

2015-01-01

Estrogens dramatically dilate numerous vascular beds with the greatest response in the uterus. Endogenous hydrogen sulfide (H2S) is a potent vasodilator and proangiogenic second messenger, which is synthesized from L-cysteine by cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE). We hypothesized that estrogen replacement therapy (ERT) selectively stimulates H2S biosynthesis in uterine artery (UA) and other systemic arteries. Intact and endothelium-denuded UA, mesenteric artery (MA), and carotid artery (CA) were obtained from ovariectomized nonpregnant ewes (n = 5/group) receiving vehicle or estradiol-17β replacement therapy (ERT). Total RNA and protein were extracted for measuring CBS and CSE, and H2S production was determined by the methylene blue assay. Paraffin-embedded UA rings were used to localize CBS and CSE proteins by immunofluorescence microscopy. ERT significantly stimulated CBS mRNA and protein without altering CSE mRNA or protein in intact and denuded UA. Quantitative immunofluorescence microscopic analyses showed CBS and CSE protein localization in endothelium and smooth muscle and confirmed that ERT stimulated CBS but not CSE protein expression in UA endothelium and smooth muscle. ERT also stimulated CBS, but not CSE, mRNA and protein expression in intact and denuded MA but not CA in ovariectomized ewes. Concomitantly, ERT stimulated UA and MA but not CA H2S production. ERT-stimulated UA H2S production was completely blocked by a specific CBS but not CSE inhibitor. Thus, ERT selectively stimulates UA and MA but not CA H2S biosynthesis by specifically up-regulating CBS expression, implicating a role of H2S in estrogen-induced vasodilation and postmenopausal women's health. PMID:25825818

Estrogen Replacement Therapy in Ovariectomized Nonpregnant Ewes Stimulates Uterine Artery Hydrogen Sulfide Biosynthesis by Selectively Up-Regulating Cystathionine β-Synthase Expression.

PubMed

Lechuga, Thomas J; Zhang, Hong-hai; Sheibani, Lili; Karim, Muntarin; Jia, Jason; Magness, Ronald R; Rosenfeld, Charles R; Chen, Dong-bao

2015-06-01

Estrogens dramatically dilate numerous vascular beds with the greatest response in the uterus. Endogenous hydrogen sulfide (H2S) is a potent vasodilator and proangiogenic second messenger, which is synthesized from L-cysteine by cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE). We hypothesized that estrogen replacement therapy (ERT) selectively stimulates H2S biosynthesis in uterine artery (UA) and other systemic arteries. Intact and endothelium-denuded UA, mesenteric artery (MA), and carotid artery (CA) were obtained from ovariectomized nonpregnant ewes (n = 5/group) receiving vehicle or estradiol-17β replacement therapy (ERT). Total RNA and protein were extracted for measuring CBS and CSE, and H2S production was determined by the methylene blue assay. Paraffin-embedded UA rings were used to localize CBS and CSE proteins by immunofluorescence microscopy. ERT significantly stimulated CBS mRNA and protein without altering CSE mRNA or protein in intact and denuded UA. Quantitative immunofluorescence microscopic analyses showed CBS and CSE protein localization in endothelium and smooth muscle and confirmed that ERT stimulated CBS but not CSE protein expression in UA endothelium and smooth muscle. ERT also stimulated CBS, but not CSE, mRNA and protein expression in intact and denuded MA but not CA in ovariectomized ewes. Concomitantly, ERT stimulated UA and MA but not CA H2S production. ERT-stimulated UA H2S production was completely blocked by a specific CBS but not CSE inhibitor. Thus, ERT selectively stimulates UA and MA but not CA H2S biosynthesis by specifically up-regulating CBS expression, implicating a role of H2S in estrogen-induced vasodilation and postmenopausal women's health.

Terrestrial source to deep-sea sink sediment budgets at high and low sea levels: Insights from tectonically active Southern California

USGS Publications Warehouse

Covault, J.A.; Romans, B.W.; Graham, S.A.; Fildani, A.; Hilley, G.E.

2011-01-01

Sediment routing from terrestrial source areas to the deep sea influences landscapes and seascapes and supply and filling of sedimentary basins. However, a comprehensive assessment of land-to-deep-sea sediment budgets over millennia with significant climate change is lacking. We provide source to sink sediment budgets using cosmogenic radionuclide-derived terrestrial denudation rates and submarine-fan deposition rates through sea-level fluctuations since oxygen isotope stage 3 (younger than 40 ka) in tectonically active, spatially restricted sediment-routing systems of Southern California. We show that source-area denudation and deep-sea deposition are balanced during a period of generally falling and low sea level (40-13 ka), but that deep-sea deposition exceeds terrestrial denudation during the subsequent period of rising and high sea level (younger than 13 ka). This additional supply of sediment is likely owed to enhanced dispersal of sediment across the shelf caused by seacliff erosion during postglacial shoreline transgression and initiation of submarine mass wasting. During periods of both low and high sea level, land and deep-sea sediment fluxes do not show orders of magnitude imbalances that might be expected in the wake of major sea-level changes. Thus, sediment-routing processes in a globally significant class of small, tectonically active systems might be fundamentally different from those of larger systems that drain entire orogens, in which sediment storage in coastal plains and wide continental shelves can exceed millions of years. Furthermore, in such small systems, depositional changes offshore can reflect onshore changes when viewed over time scales of several thousand years to more than 10 k.y. ?? 2011 Geological Society of America.

Direct sampling of sub-µm atmospheric particulate organic matter in sub-ng m-3 mass concentrations by proton-transfer-reaction mass spectrometry

NASA Astrophysics Data System (ADS)

Armin, W.; Mueller, M.; Klinger, A.; Striednig, M.

2017-12-01

A quantitative characterization of the organic fraction of atmospheric particulate matter is still challenging. Herein we present the novel modular "Chemical Analysis of Aerosol Online" (CHARON) particle inlet system coupled to a new-generation proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF 6000 X2, Ionicon Analytik, Austria) that quantitatively detects organic analytes in real-time and sub-pptV levels by chemical ionization with hydronium reagent ions. CHARON consists of a gas-phase denuder for stripping off gas-phase analytes (efficiency > 99.999%), an aerodynamic lens for particle collimation combined with an inertial sampler for the particle-enriched flow and a thermodesorption unit for particle volatilization prior to chemical analysis. With typical particle enrichment factors of around 30 for particle diameters (DP) between 120 nm and 1000 nm (somewhat reduced enrichment for 60 nm < DP < 120 nm) we boost the already excellent limits of detection of the PTR-TOF 6000 X2 system to unprecedented levels. We demonstrate that particulate organic analytes of mass concentrations down to 100 pg m-3 can be detected on-line and in single-minute time-resolutions. In addition, PTR-MS allows for a quantitative detection of almost the full range of particulate organics of intermediate to low volatility. With the high mass resolution (R > 6000) and excellent mass accuracies (< 10 ppm) chemical compositions can be assigned and included in further analyses. In addition to a detailed characterization of the CHARON PTR-TOF 6000 X2 we will present first results on the chemical composition of sub-µm particulate organic matter in the urban atmosphere in Innsbruck (Austria).

40 CFR 61.51 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... produce chlorine gas, hydrogen gas, and alkali metal hydroxide. (f) Mercury chlor-alkali electrolyzer... converted to alkali metal hydroxide, mercury, and hydrogen gas in a short-circuited, electrolytic reaction. (h) Hydrogen gas stream means a hydrogen stream formed in the chlor-alkali cell denuder. (i) End box...

40 CFR 61.51 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... produce chlorine gas, hydrogen gas, and alkali metal hydroxide. (f) Mercury chlor-alkali electrolyzer... converted to alkali metal hydroxide, mercury, and hydrogen gas in a short-circuited, electrolytic reaction. (h) Hydrogen gas stream means a hydrogen stream formed in the chlor-alkali cell denuder. (i) End box...

40 CFR 61.51 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... produce chlorine gas, hydrogen gas, and alkali metal hydroxide. (f) Mercury chlor-alkali electrolyzer... converted to alkali metal hydroxide, mercury, and hydrogen gas in a short-circuited, electrolytic reaction. (h) Hydrogen gas stream means a hydrogen stream formed in the chlor-alkali cell denuder. (i) End box...

40 CFR 61.51 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... produce chlorine gas, hydrogen gas, and alkali metal hydroxide. (f) Mercury chlor-alkali electrolyzer... converted to alkali metal hydroxide, mercury, and hydrogen gas in a short-circuited, electrolytic reaction. (h) Hydrogen gas stream means a hydrogen stream formed in the chlor-alkali cell denuder. (i) End box...

40 CFR 61.51 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... produce chlorine gas, hydrogen gas, and alkali metal hydroxide. (f) Mercury chlor-alkali electrolyzer... converted to alkali metal hydroxide, mercury, and hydrogen gas in a short-circuited, electrolytic reaction. (h) Hydrogen gas stream means a hydrogen stream formed in the chlor-alkali cell denuder. (i) End box...

Hydrogeology of the karst of Puerto Rico

USGS Publications Warehouse

Giusti, Ennio V.

1978-01-01

About one-fifth of Puerto Rico is covered by a tropical karst formed on a series of six limestone formations ranging in age from middle-Oligocene to middle Miocene. These formations strike east to west and crop out over the north coast of the island. Structurally, the rocks form a simple wedge abutting southward against a mountain chain of volcanic origin and thickening northward to about 1,400 meters by the seashore. All stages of karstification are present: from the incipient, found at the western end of the belt to the residual, found at the eastern end. Maximum development of sinkholes occurs on the Aguada Limestone and upper part of the Aymanom Limestone. These formations have a CaCO3 content range from about 85 to 95 percent. The denudation rate of the Limestone belt through solution is computed as 0.70 mm per year with some evidence that abrasion may increase the denudation rate locally by as much as 40 percent. (Woodard-USGS)

Land use and sediment yield

USGS Publications Warehouse

Leopold, Luna Bergere; Thomas, William L.

1956-01-01

When the vegetal cover is removed from a land surface, the rate of removal of the soil material, at least initially, increases rapidly. So well known is this principle that it hardly needs restatement.If attention is focused on any individual drainage basin in its natural state, large or small, and inquiry is made as to the rate of denudation, a quantitative answer is not easily obtained. The possible error in any computation of rate of sediment production from any given drainage basin is considerable. Significant variations are found in sediment yields from closely adjacent watersheds which appear to be generally similar. To make a quantitative evaluation of the change in the rate of denudation when the natural vegetation is disturbed is, therefore, even more difficult. Considering the fact that "soil conservation" has been promoted to the status of a science, our lack of ability to answer what is apparently so simple a question may seem surprising. Let us look at some of the reasons.

The dominant alopecia phenotypes Bareskin, Rex-denuded, and Reduced Coat 2 are caused by mutations in gasdermin 3.

PubMed

Runkel, F; Marquardt, A; Stoeger, C; Kochmann, E; Simon, D; Kohnke, B; Korthaus, D; Wattler, F; Fuchs, H; Hrabé de Angelis, M; Stumm, G; Nehls, M; Wattler, S; Franz, T; Augustin, M

2004-11-01

Reduced Coat 2 (Rco2) is an ENU-induced mutation affecting hair follicle morphogenesis by an abnormal and protracted catagen. We describe chromosomal mapping and molecular identification of the autosomal dominant Rco2 mutation. The Rco2 critical region on mouse chromosome 11 encompasses the alopecia loci, Bareskin (Bsk), Rex-denuded (Re(den)), Recombination induced mutation 3 (Rim3), and Defolliculated (Dfl). Recently, the gasdermin (Gsdm) gene was described as predominantly expressed in skin and gastric tissues. We provide evidence for a murine-specific gene cluster consisting of Gsdm and two closely related genes which we designate as Gsdm2 and Gsdm3. We show that Gsdm3 reflects a mutation hotspot and that Gsdm3 mutations cause alopecia in Rco2, Re(den), and Bsk mice. We infer a role of Gsdm3 during the catagen to telogen transition at the end of hair follicle morphogenesis and the formation of hair follicle-associated sebaceous glands.

A comparison of the impact of 'seagrass-friendly' boat mooring systems on Posidonia australis.

PubMed

Demers, Marie-Claire A; Davis, Andrew R; Knott, Nathan A

2013-02-01

Permanent boat moorings have contributed to the decline of seagrasses worldwide, prompting the development of 'seagrass-friendly' moorings. We contrasted seagrass cover and density (predominantly Posidonia australis) in the vicinity of three mooring types and nearby reference areas lacking moorings in Jervis Bay, Australia. We examined two types of 'seagrass-friendly' mooring and a conventional 'swing' mooring. 'Swing' moorings produced significant seagrass scour, denuding patches of ~9 m radius. Seagrass-friendly 'cyclone' moorings produced extensive denuded patches (average radius of ~18 m). Seagrass-friendly 'screw' moorings, conversely, had similar seagrass cover to nearby reference areas. Our findings reinforce previous work highlighting the negative effects of 'swing' and 'cyclone' moorings. In contrast, the previously unstudied 'screw' moorings were highly effective. We conclude that regular maintenance of moorings and the monitoring of surrounding seagrass are required to ensure that 'seagrass-friendly' moorings are operating effectively. This is important, as following damage Posidonia will take many decades to recover. Copyright © 2012 Elsevier Ltd. All rights reserved.

Global spatial indexing of the human impact on Al, Cu, Fe, and Zn mobilization.

PubMed

Rauch, Jason N

2010-08-01

With increasing consumption of material by human activity, the extent of human influence relative to nature in the mobilization of metals and other elements on Earth continues to grow. Recognizing people as modern geomorphic agents, I produced global data layers at 1 degreesx1 degrees of human-mediated mass flows (coal combustion, biomass burning, and mining) and nature-mediated mass flows (net primary productivity, sea salt aerosol emission, and denudation to the oceans) for the industrial metals of aluminum, iron, copper, and zinc for the year 2000. The major mobilization processes are denudation (natural) and mining (anthropic), though net primary productivity for Zn and Cu and coal combustion for Al are nearly as significant. All flows are subsequently combined into an index representing human versus nature flow dominance. As the first maps of mobilization flows of metals widely used by modern technology, they reveal that approximately 1-5% (depending upon the metal) of Earth's land surface now has metal flow dominated by human activity.

Phanerozoic burial, uplift and denudation of the Equatorial Atlantic margin of South America

NASA Astrophysics Data System (ADS)

Japsen, Peter; Bonow, Johan M.; Green, Paul F.; dall'Asta, Massimo; Roig, Jean-Yves; Theveniaut, Hervé

2017-04-01

We have initiated a study aimed at understanding the history of burial, uplift and denudation of the South American Equatorial Atlantic Margin (SAEAM Uplift) including the Guiana Shield to provide a framework for investigating the hydrocarbon prospectivity of the offshore region. We report first results including observations from fieldwork at the northern and southern flank of the Guiana Shield. The study combines apatite fission-track analysis (AFTA) and vitrinite reflectance data from samples of outcrops and drillcores, sonic velocity data from drill holes and stratigraphic landscape analysis (mapping of peneplains) - all constrained by geological evidence, following the methods of Green et al. (2013). The study will thus combine the thermal history from AFTA data with the denudation history from stratigraphic landscape analysis to provide magnitudes and timing of vertical movements (Japsen et al. 2012, 2016). Along the Atlantic margin of Suriname and French Guiana, tilted and truncated Lower Cretaceous strata rest on Precambrian basement (Sapin et al. 2016). Our AFTA data show that the basement underwent Mesozoic exhumation prior to deposition of the Lower Cretaceous cover. Sub-horizontal peneplains define the landscape of the Guiana Shield at elevations up to 500 m a.s.l. As these sub-horizontal peneplains truncate the tilted, sub-Cretaceous surface along the Atlantic margin, these peneplains were therefore formed and uplifted in post-Cretaceous time. This interpretation is in good agreement with our AFTA data that define Paleogene exhumation along the margin and with the results of Theveniaut and Freyssinet (2002) who used palaeomagnetic data to conclude that bauxitic surfaces across basement at up to 400 m a.s.l. on the Guiana Shield formed during the Palaeogene. Integration of the results from AFTA with stratigraphic landscape analysis (currently in progress) and geological evidence will provide a robust reconstruction of the tectonic development of the onshore margin. References Green, Lidmar-Bergström, Japsen, Bonow & Chalmers 2013: Stratigraphic landscape analysis, thermochronology and the episodic development of elevated passive continental margins. GEUS Bulletin. Japsen, Green, Bonow & Erlström 2016: Episodic burial and exhumation of the southern Baltic Shield: Epeirogenic uplifts during and after break-up of Pangea. Gondwana Research. Japsen, Bonow, Green, Cobbold, Chiossi et al. 2012: Episodic burial and exhumation history of NE Brazil after opening of the South Atlantic. GSA Bulletin. Sapin, Davaux, dall'Asta et al. 2016: Post-rift subsidence of the French Guiana hyper-oblique margin: from rift-inherited subsidence to Amazon deposition effect. Geol. Soc. Spec. Publ. Theveniaut & Freyssinet 2002: Timing of lateritization on the Guiana Shield: synthesis of paleomagnetic results from French Guiana and Suriname. 3 x Palaeo.

Long-term subsidence, cooling, and exhumation history along the South Atlantic passive continental margin in NW-Namibia

NASA Astrophysics Data System (ADS)

Menges, Daniel; Glasmacher, Ulrich Anton; Salomon, Eric; Hackspacher, Peter Christian; Schneider, Gabi

2016-04-01

In northwest Namibia the Kaoko Belt is one of the most important Precambrian crustal segments that have stored the subsidence, cooling, and exhumation history of Namibia since the Neoproterozoic. ZFT-ages are processed to give new insights on this early evolution. Paleozoic to Mesozoic sedimentary rocks of the Karoo Supergroup and the Lower Cretaceous volcanic rocks of the Etendeka sequence overlay the Proterozoic metamorphic and intrusive rocks (1). New apatite fission-track (AFT) ages range from 390.9 (17.9) Ma to 80.8 (6.0) Ma. Along the coast apatites of Proterozoic rock samples reveal the youngest ages. Further inland the ages increase significantly. In addition, rapid change of AFT-ages occurs on both sides of major thrust and shear zones. Using the oldest thermochronological data the revealed t-T paths indicate a long era of exhumation, starting at the end of the Pan-African Orogeny in the Neoproterozoic and continuing into the Permo-Carboniferous. The subsequent sedimentation of the Karoo Supergroup initiates a new era of subsidence until the end of Triassic (2). The subsequent period of denudation ends abruptly with the rapid deposition of the Etendeka basalts in the Early Cretaceous (3). The maximum thickness of the Etendeka volcanic suite has been estimated, using the apatite fission-track data, to about 3.2 (1.2) km. With the ongoing opening of the South Atlantic and the formation of the continental margin the Kaoko Belt went through a rapid cooling event starting ~ 130 Ma and ending ~ 80 Ma, at a mean rate of 0.034 km/Ma for the western, and 0.018 km/Ma for the northern and eastern Kaoko Belt. This cooling event was accompanied by a reactivation of major fault zones, like the Purros Mylonite Zone (4). Thereafter, stable conditions were established, with denudation rates generally lower than 0.010 km/Ma, until the Neogene, where a second cooling event led to increased exhumation rates around 0.042 km/Ma. The total amount of denudation in the last 130 Ma has been estimated to ~ 2.7 km in the northeastern and ~ 4 km in the western Kaoko Belt. References 1. Miller, R.McG. Becker, T., 2008. The Geology of Namibia: Ministry of Mines and Energy, Geological Survey (Namibia). 2. Stollhofen, H., 1999. Karoo Synrift-Sedimentation und ihre tektonische Kontrolle am entstehenden Kontinentalrand Namibias: Z.dt.geol.Ges. 149: 519-632. 3. Renne, P.R., Glen, J.M., Milner, S.C., Duncan, A.R., 1996. Age of Etendeka flood volcanism and associated intrusions in southwestern Africa: Geology 24 (7): 659- 662. 4. Salomon, E., Koehn, D., Passchier, C., 2014. Brittle reactivation of ductile shear zones in NW Namibia in relation to South Atlantic rifting: Tectonics 34, 70-85.

Estimating ammonia volatilization and deposition from fertilized vegetation

NASA Astrophysics Data System (ADS)

Heuer, M. W.; Myles, L.

2010-12-01

Deposition of reactive nitrogen in the form of atmospheric ammonia (NH3) affects ecosystem dynamics. Large amounts of atmospheric ammonia can volatilize from fertilized vegetation and deposit to adjacent areas, contributing to changes in soil and plant chemistry. To study the air-surface exchange of ammonia, instrumentation was installed from February 15 through April 12, 2010 at an agricultural research area of managed crops and grassland near Knoxville, TN. A Picarro ammonia analyzer was deployed to measure ammonia at two heights (z = 0.5 m and 2 m) near a plot of winter wheat fertilized with urea. Integrated samples of ammonia were also collected with annular denuder systems at both heights. Concentrations from the Picarro averaged 3-4 ppb of ammonia, but increased by a factor of 20 during fertilization. Fluxes were derived from concurrent measurements of ammonia concentration and air temperature using the flux-gradient method.

Late Neogene exhumation of the Piceance basin, N.W. Colorado, USA: Integrated analysis of multiple thermochronometers and subsidence modeling

NASA Astrophysics Data System (ADS)

Vernon, A. J.; Kendall, J. J.; Becker, T. P.; Patterson, P. E.; Reiners, P. W.; Kapp, J.

2010-12-01

The retrograde history of sedimentary basins is often poorly constrained by the study of subsidence, compaction, and thermal diffusion models. As part of industry/academic collaborative research on the fundamental processes active in convergent tectonics we combined multiple paleothermometers, paleobarometers, and thermochronometers on deep borehole samples with modern heat flow measurements to provide powerful constraint for estimating the exhumation history in an area. The Piceance basin (N.W. Colorado) lies east of the leading edge of the Cretaceous to early Eocene Sevier thrust belt, and is flanked by several basement-involved structures (Douglas Creek arch, White River dome, Uinta uplift, White River uplift) that exhibit growth from the Maastrichtian through the late Eocene. The youngest preserved strata within the Piceance basin are within the early Oligocene Uinta Formation, although there are deposits as young as Miocene locally preserved in the region that may have also capped the basin. The timing of uplift, river incision, and plateau-scale exhumation within this region fits into the larger context of the evolution of the Colorado River drainage system. A series of core, cutting, and surface samples were compiled to develop a synthetic well (or vertical section) of over 5000 m. Samples were collected from stratigraphic intervals ranging from the Jurassic to the Eocene and analyzed for apatite and zircon U-Th/He ages, as well as apatite fission track length distributions and ages. As the exhumation model was the unconstrained parameter, the timing and magnitude of the cooling associated with such an event was systematically varied. Thermal histories of each sampled interval were extracted from differing exhumation scenarios in the Piceance basin model (which tracks the temperature and pressure evolution during burial and denudation) and forward modeled using HeFTy. The combined use of several thermochronometers (apatite and zircon U-Th/He, apatite fission tracks), as well as vitrinite reflectance and multi-phase fluid inclusion thermometry and barometry yields a best-fit thermal history that corresponds to ~ 1.5 km of exhumation in the last 4 million years (~0.38 mm/yr). The timing of the thermal lapse associated with the epierogenic uplift of the western United States is not well constrained, but did figure into these estimates of exhumation timing in the Piceance basin region. Estimates of modern rates of denudation derived from suspended sediment yields are considerably lower than our datasets suggest (~0.011 mm/yr), which suggest a transient period of Plio-Pleistocene unroofing. The onset of volcanism and hydrothermal mineralization within the Colorado mineral belt may constitute an additional factor to consider within the plateau exhumation history.

Arid oil-field restoration: native perennial grasses suppress weeds and erosion, but also suppress native shrubs

USDA-ARS?s Scientific Manuscript database

1. Long-lived, drought-tolerant shrubs are dominant components of many arid ecosystems, and shrubs provide multiple ecosystem services (e.g., soil stabilization, herbaceous plant facilitation, carbon storage and wildlife habitat). On denuded sites, shrub restoration is hindered by abiotic (erosion ...

Aerial mulching techniques-trough fire

Treesearch

Robert Faust

2008-01-01

The Trough fire occurred in August 2001 on the Mendocino National Forest of northern California. A burned area emergency rehabilitation team evaluated the fire effects on the watershed. Concerns were soil from the denuded slopes moving into streams affecting fishery values, reservoir sedimentation and storm runoff plugging culverts leading to road wash outs. Past...

Development of an early warning sensor and network for brown-\\0xAD\\0x2010out conditions.

DOT National Transportation Integrated Search

2016-03-31

Brownout conditions on motorways are caused by windblown dust and sand from upwind areas where : soils are susceptible to wind erosion. Owing in part to prolonged droughts that have dried : soils and denuded vegetation and biological crusts, large, m...

DEVELOPMENT AND CHARACTERIZATION OF AN ANNULAR DENUDER METHODOLOGY FOR THE MEASUREMENT OF DIVALENT INORGANIC REACTIVE GASEOUS MERCURY IN AMBIENT AIR

EPA Science Inventory

Atmospheric mercury is predominantly present in the gaseous elemental form (Hg0). However, anthropogenic emissions (e.g. incineration, fossil fuel combustion) emit and natural processes create particulate-phase mercury (Hg(p)) and divalent reactive gas-phase mercury (RGM). RG...

RECLAMATION OF TOXIC MINE WASTE UTILIZING SEWAGE SLUDGE CONTRARY CREEK DEMONSTRATION PROJECT

EPA Science Inventory

Three abandoned pyrite mines in central Virginia that had been inactive since 1923 contained about 12 denuded ha and caused severe acid mine drainage (AMD) in a small stream known as Contrary Creek. The AMD included heavy metals and rendered the stream virtually void of aquatic l...

East Europe Report, Political, Sociological and Military Affairs, No. 2170

DTIC Science & Technology

1983-07-25

thoughts of the following. /Captain Kiril Popov,/ platoon commander: "Though in sharply critical but realistic form, the article is to my liking. It...callup other patrol sectors are denuded." /Maj Angel Dimitrov ,/ rayon administration deputy chief: "The article stirred up great interest among

Recovery of a Bryophyte Community on Hurricane Island, Maine

Treesearch

R.E. Leonard; P.W. Conkling; J.L. McMahon; J.L. McMahon

1984-01-01

Recovery of a bryophyte community on an artifically denuded granite ledge was monitored for 4 years on Hurricane Island, Maine. Predominant bryophyte species were Dicranum polysetum, Polytrichum juniperinurn, Dicranum flagellare, Polytrichum piliferum, and Dicranum fuscescens. Site factors such as nutrient supply, moisture, and availability of reproductive material...

Soil Properties and Productivity as Affected by Topsoil Movement within an Eroded Landform

USDA-ARS?s Scientific Manuscript database

In hilly landforms subject to long-term cultivation, erosion has denuded upper slope positions of topsoil and accumulated topsoil in lower slope positions. One approach to remediate these eroded landforms is moving soil from areas of topsoil accumulation to areas of topsoil depletion, termed here so...

Geomorphology, denudation rates, and stream channel profiles reveal patterns of mountain building adjacent to the San Andreas fault in northern California, USA

USGS Publications Warehouse

DeLong, Stephen B.; Hilley, George E.; Prentice, Carol S.; Crosby, Christopher J.; Yokelson, Intan N.

2017-01-01

Relative horizontal motion along strike-slip faults can build mountains when motion is oblique to the trend of the strike-slip boundary. The resulting contraction and uplift pose off-fault seismic hazards, which are often difficult to detect because of the poor vertical resolution of satellite geodesy and difficulty of locating offset datable landforms in active mountain ranges. Sparse geomorphic markers, topographic analyses, and measurement of denudation allow us to map spatiotemporal patterns of uplift along the northern San Andreas fault. Between Jenner and Mendocino, California, emergent marine terraces found southwest of the San Andreas fault record late Pleistocene uplift rates between 0.20 and 0.45 mm yr–1 along much of the coast. However, on the northeast side of the San Andreas fault, a zone of rapid uplift (0.6–1.0 mm yr–1) exists adjacent to the San Andreas fault, but rates decay northeastward as the coast becomes more distant from the San Andreas fault. A newly dated 4.5 Ma shallow-marine deposit located at ∼500 m above sea level (masl) adjacent to the San Andreas fault is warped down to just 150 masl 15 km northeast of the San Andreas fault, and it is exposed at just 60–110 masl to the west of the fault. Landscape denudation rates calculated from abundance of cosmogenic radionuclides in fluvial sediment northeast of, and adjacent to, the San Andreas fault are 0.16–0.29 mm yr–1, but they are only 0.03–0.07 mm yr–1 west of the fault. Basin-average channel steepness and the denudation rates can be used to infer the erosive properties of the underlying bedrock. Calibrated erosion rates can then be estimated across the entire landscape using the spatial distribution of channel steepness with these erosive properties. The lower-elevation areas of this landscape that show high channel steepness (and hence calibrated erosion rate) are distinct from higher-elevation areas with systematically lower channel steepness and denudation rates. These two areas do not appear to be coincident with lithologic contacts. Assuming that changes in rock uplift rates are manifest in channel steepness values as an upstream-propagating kinematic wave that separates high and low channel steepness values, the distance that this transition has migrated vertically provides an estimate of the timing of rock uplift rate increase. This analysis suggests that rock uplift rates along the coast changed from 0.3 to 0.75 mm yr–1 between 450 and 350 ka. This zone of recent, relatively rapid crustal deformation along the plate boundary may be a result of the impingement of relatively strong crust underlying the Gualala block into the thinner, weaker oceanic crust left at the western margin of the North American plate by the westward migration of the subduction zone prior to establishment of the current transform plate boundary. The warped Pliocene marine deposits and the presence of a topographic ridge support the patterns indicated by the channel steepness analyses, and further indicate that the zone of rapid uplift may herald elevated off-fault seismic hazard if this uplift is created by periodic stick-slip motion on contractional structures.

New thermochronometric constraints on the Tertiary landscape evolution of the central and eastern Grand Canyon, Arizona

USGS Publications Warehouse

Lee, John P.; Stockli, Daniel F.; Kelley, S.A.; Pederson, J.; Karlstrom, K.E.; Ehlers, T.A.

2013-01-01

Thermal histories are modeled from new apatite (U-Th)/He and apatite fission-track data in order to quantitatively constrain the landscape evolution of the Grand Canyon region. Fifty new samples and their associated thermochronometric ages are presented here. Samples span from Lee’s Ferry in the east to Quartermaster Canyon in the west and include four age-elevation transects into Grand Canyon and borehole samples from the Coconino Plateau. Twenty-seven samples are inversely modeled to provide continuous thermal histories. This represents the most extensive and complete dataset on patterns of long-term exhumation in the Grand Canyon region, and it enables us to constrain the timing and magnitude of erosion and also discriminate between canyon incision and broader planation. The new data suggest that the early Cenozoic landscape in eastern Grand Canyon was low in relief and does not indicate the presence of an early Cenozoic precursor to the modern Grand Canyon. However, there is evidence for the incision of a smaller-scale canyon across the Kaibab Uplift at 28–20 Ma. This middle-Cenozoic denudation event was accompanied by the removal of a majority of remaining Mesozoic strata west of the Kaibab Uplift. In contrast, just upstream in the area of Lee’s Ferry, ∼2 km of Mesozoic strata remained over the middle Cenozoic and were removed after 10 Ma.

Earth is (mostly) flat: Apportionment of the flux of continental sediment over millennial time scales: COMMENT

USGS Publications Warehouse

Warrick, J.A.; Milliman, John D.; Walling, D.E.; Wasson, R.J.; Syvitski, J.P.M.; Arno, Stephen F.

2014-01-01

Recent synthesis of 10Be-derived denudation rates by Willenbring et al. (2013) suggests that the “flat” areas of the world, those with average slopes of 2) using landscape slope as the controlling variable. We suggest that these findings are incorrect on several grounds.

Sediment traps for measuring onslope surface sediment movement

Treesearch

Wade G. Wells; Peter M. Wohlgemuth

1987-01-01

Two types of small (30-cm aperture) sheet metal sediment traps were developed to monitor onslope surface sediment transport. Traditionally, sediment traps and erosion pins have been used to measure the onslope movement of surficial soil material. While pins may be appropriate for documenting landscape denudation, traps are more suitable for monitoring downslope...

Management of gingival recession by the use of an acellular dermal graft material: a 12-case series.

PubMed

Santos, A; Goumenos, G; Pascual, A

2005-11-01

Different soft tissue defects can be treated by a variety of surgical procedures. Most of these techniques require the palatal area as a donor site. Recently, an acellular dermal graft has become available that can substitute for palatal donor tissue. This study describes the surgical technique for gingival augmentation and root coverage and the results of 12 clinical cases. A comparison between the three most popular mucogingival procedures for root coverage is also presented. The results of the 12 patients and the 26 denuded surfaces have shown that we can obtain a mean root coverage of 74% with the acellular dermal graft. Thirteen out of the 26 denuded surfaces had complete root coverage. The average increase in keratinized tissue was 1.19 mm. It seems that the long-term results of the cases are stable. The proposed technique of root coverage with an acellular dermal graft can be a good alternative to soft tissue grafts for root coverage, and it should be part of our periodontal plastic surgery armamentarium.

Erosion and sediment yields in the Transverse Ranges, Southern California

USGS Publications Warehouse

Scott, Kevin M.; Williams, Rhea P.

1978-01-01

Major-storm and long-term erosion rates in mountain watersheds of the western Transverse Ranges of Ventura County, Calif., are estimated to range from low values that would not require the construction of catchments or channel-stabilization structures to values as high as those recorded anywhere for comparable bedrock erodibilities. A major reason for this extreme variability is the high degree of tectonic activity in the area--watersheds are locally being uplifted by at least as much as 25 feet per 1,000 years, yet the maximum extrapolated rate of denudation measured over the longest available period of record is 7.5 feet per 1,000 years adjusted to a drainage area of 0.5 square mile. Evidence of large amounts of uplift continuing into historic time includes structurally overturned strata of Pleistocene age, active thrust faulting, demonstrable stream antecedence, uplifted and deformed terraces, and other results of base-level change seen in stream channels. Such evidence is widespread in the Transverse Ranges, and aspects of the landscape are locally more a function of tectonic activity than of the denudational process. (Woodard-USGS)

Mars, Always Cold, Sometimes Wet: New Constraints on Mars Denudation Rates and Climate Evolution from Analog Studies at Haughton Crater, Devon Island, High Arctic

NASA Technical Reports Server (NTRS)

Lee, Pascal; Boucher, M.; Desportes, C.; Glass, B. J.; Lim, D.; McKay, C. P.; Osinski, G. R.; Parnell, J.; Schutt, J. W.

2005-01-01

Analysis of crater modification on Mars and at Haughton Crater, Devon Island, High Arctic, which was recently shown to be significantly older than previously believed (Eocene age instead of Miocene) [1], suggest that Mars may have never been climatically wet and warm for geological lengths of time during and since the Late Noachian. Impact structures offer particularly valuable records of the evolution of a planet s climate and landscape through time. The state of exposure and preservation of impact structures and their intracrater fill provide clues to the nature, timing, and intensity of the processes that have modified the craters since their formation. Modifying processes include weathering, erosion, mantling, and infilling. In this study, we compare the modification of Haughton through time with that of impact craters in the same size class on Mars. We derive upper limits for time-integrated denudation rates on Mars during and since the Late Noachian. These rates are significantly lower than previously published and provide important constraints for Mars climate evolution.

Denudational slope processes on weathered basalt in northern California: 130 ka history of soil development, periods of slope stability and colluviation, and climate change

NASA Astrophysics Data System (ADS)

McDonald, Eric; Harrison, Bruce; Baldwin, John; Page, William; Rood, Dylan

2017-04-01

The geomorphic history of hillslope evolution is controlled by multiple types of denudational processes. Detailed analysis of hillslope soil-stratigraphy provides a means to identify the timing of periods of slope stability and non-stability, evidence of the types of denudational processes, and possible links to climatic drivers. Moreover, the degree of soil formation and the presence of buried or truncated soils provide evidence of the relative age of alternating periods of colluviation and stability. We use evaluation of soil stratigraphy, for a small forested hillslope (<500 m of slope length) located in the Cascades of northern California, to elucidate both the timing and processes controlling 130 ka of hillslope evolution. The soils and slope colluvium are derived from highly weathered basalt. Stratigraphic interpretation is reinforced with soil profile development index (PDI) derived age estimates, tephrochronology, luminescence ages on colluvium, and He3 nuclide exposure dates. Soils formed along hilltop ridges are well developed and reflect deep (>2-3 m) in-situ weathering of the basalt bedrock. PDI age estimates and He3 exposure dates indicate that these hilltop soils had been in place for 100-130 ka, implying a long period of relative surface stability. At about 40-30 ka, soil stratigraphy indicates the onset of 3 distinct cycles of denudation of the hilltop and slopes. Evidence for changes in stability and onset of soil erosion is the presence of several buried soils formed in colluvium downslope of the hilltop. These buried soils have formed in sediment derived from erosion of the hilltop soils (i.e. soil parent material of previously weathered soil matrix and basalt cobbles). The oldest buried soil indicates that slope stability was re-established between 32-23 ka, with stability and soil formation lasting to about 10 ka. Soil-stratigraphy indicates that two additional intervals of downslope transport of sediment between 6-10 ka, and 2-5 ka. Soil properties indicate that the primary method of downslope transport is largely due to tree throw and faunal burrowing. Onset of slope instability at 40-30 ka appears to be related to changes in vegetation with establishment of a pine dominated forest (increase in tree throw) and/or onset of local faulting. By comparison, slope stability from 30-10 ka appears to be a related to the formation of a shrub dominated steppe and a decrease in tree throw. The two periods of slope erosion after 10 ka appear related to regional periods of pronounced channel incision. Results indicate that soil stratigraphy can provide a key record of slope evolution and related paleoenvironmental changes.

Late Cenozoic Climate Change and its Implications on the Denudation of Orogen Syntaxes

NASA Astrophysics Data System (ADS)

Mutz, Sebastian; Ehlers, Todd

2017-04-01

The denudation history of active orogens is often interpreted in the context of modern climate gradients. Despite the influence of climatic conditions on erosion rates, information about paleoclimate evolution is often not available and thus not considered when denudation histories are interpreted. In this study, we analyze output from paleoclimate simulations conducted with ECHAM5-wiso at T159 (ca. 80x80km) resolution. Specifically, we analyze simulations of pre-industrial (PI, pre-1850), Mid-Holocene (MH, ca. 6ka), Last Glacial Maximum (LGM, ca. 21ka) and Pliocene (PLIO, ca. 3ka) climates and focus on a selection of orogen syntaxes as study regions (e.g. Himalaya, SE Alaska, Cascadia, and Central Andes). For the selected region, we carry out a cluster analysis using a hybrid of hierarchical and k-means clustering procedures using mean annual temperature (MAT), temperature amplitude, mean annual precipitation (MAP), precipitation amplitude and u-wind and v-wind in different months to provide a general overview of paleoclimates in the study regions. Additionally, we quantify differences between paleoclimates by applying two-group linear discrimination analyses to the simulation output for a similar selection of variables. Results indicate the largest differences to the PI climate are observed for the LGM and PLIO climates in the form of widespread cooling and reduced precipitation in the LGM and warming and enhanced precipitation during the PLIO. These global trends can be observed for most locations in the investigated areas, but the strength varies regionally and the trends in precipitation are less uniform than trends in temperatures. The LGM climate shows the largest deviation in annual precipitation from the PI climate, and shows enhanced precipitation in the temperate Andes, and coastal regions for both SE Alaska and the US Pacific Northwest Pacific. Furthermore, LGM precipitation is reduced in the western Himalayas and enhanced in the eastern Himalayas, resulting in a shift of the wettest regional climates eastward along the orogen towards the eastern syntax. The cluster-analysis results also suggest more climatic variability across latitudes east of the Andes in the PLIO climate than in other time-slice experiments conducted here. Results from the discriminant analysis show that the quantified differences in climate and the relative contribution to these differences by each of the analyzed parameters are highly variable in space for each of the paleoclimates. Taken together, these results highlight significant changes in Late Cenozoic regional climatology over active orogens on time scales ranging from glacial cycles to geologic. As a result, future interpretation of recent and paleo denudation rates in these areas from sediment flux inventories, cosmogenic radionuclides, or low-temperature thermochronology techniques warrant careful consideration of these changes.

Monte Carlo approaches to sampling forested tracts with lines or points

Treesearch

Harry T. Valentine; Jeffrey H. Gove; Timothy G. Gregoire

2001-01-01

Several line- and point-based sampling methods can be employed to estimate the aggregate dimensions of trees standing on a forested tract or pieces of coarse woody debris lying on the forest floor. Line methods include line intersect sampling, horizontal line sampling, and transect relascope sampling; point methods include variable- and fixed-radius plot sampling, and...

Integrating Geochemical and Morphologic Evolution of Soil-Covered Hillslopes in a Transient Tributary Basin

NASA Astrophysics Data System (ADS)

Weinman, B. A.; Yoo, K.; Mudd, S. M.; Hurst, M. D.; Maher, K.; Mayer, K.; Andersen, C.

2010-12-01

When hillslopes respond to incision triggered by tectonic uplift, there is a competition between chemical and physical processes in shaping the landscape. We are studying a tributary basin of the Middle Folk Feather River (FR) in Sierra Nevada CA, where an incision signal is still propagating throughout the basin. Soils were sampled along 3 hillslope transects: POMD (30% slope at 766m), FTA (56% slope at 673m), and BRC (63% slope at 684m). Given their different elevations, slopes, and proximities to the rejuvenating channel, these hillslopes presumably reflect a wide range of denudation. To capture how the basin’s geophysical and geochemical signals propagate upslope, transects were chosen so that POMD is above the knickpoint, FTA is proximal to the knickpoint, and BRC captures erosion below the knickpoint transition. Surprisingly, the hillslopes--despite their varying rates of denudation--show a constant soil thicknesses along all transects (50cm). Despite this similarity, geochemical differences between the soils do exist, indicating a connection between soil geochemistry and the turnover time of the soils (i.e., soil thickness divided by physical erosion rate). For instance, POMD (with a residence time ~30kyr) visually and chemically had the highest degree of weathering based on soil color (10YR 5/4) and the abundance of pedogenic iron oxides (0.3-0.7%). FTA and BRC, on the other hand, had residence times ~2 & 4kyr, and were less red and less Fe-oxide enriched than the POMD soils (10YR 7/4, ND-0.5%). Geochemical differences were further shown by Zr enrichments in the fine fractions of POMD and FTA soils. In general, POMD soils show 20% more mass-loss of major elements, such as Fe, Al, Na, and K in the upper horizons. However, it’s important to note that despite this difference, the geochemical profiles of FTA and POMD show strikingly similar levels of element depletion. While we are working on understanding if this similarity is due to weathering rate differences or chemical weathering occurring below the soil-saprolite boundary, the transect chemical differences, combined with grainsize results, indicate that the breakdown of coarse fractions in the regolith (>2mm) can be responsible for much of the weathering in the FR basin. This is important because our findings indicate that despite order of magnitude differences in denudation rates and soil residence times, soils with relatively fast residence times can display remarkable similarities to those exhibited by long-residence time soils. These findings are consistent with the view that soils with shorter residence times do occur on steeper hillslopes, however they contrast original expectations that soils would thin and be more physically dominated along hillslopes with steeper gradients. We think, therefore, that another control beside the dynamic chemical and physical processes we report here--namely tree throw--is a key factor in the soil formation processes in both the older and newly incising areas of FR.

Weathering and denudation history of the western continental margin of India constrained by combined Ar-Ar dating and paleomagnetism

NASA Astrophysics Data System (ADS)

Jean, Amandine; Mathé, Pierre-Etienne; Beauvais, Anicet; Chardon, Dominique; Demory, François; Janwari, Shazia

2017-04-01

The western continental passive margin of Peninsular India is fringed by an escarpment, the Western Ghats escarpment (WGE), which separates a narrow coastal lowland plain drained to the west from a highland plateau drained to the east. Since Deccan Traps emplacement, the combined effects of chemical alteration and mechanical erosion led to the formation and dissection of lateritic landscapes whose relicts are preserved both sides of the WGE. Ar-Ar ages of K-rich manganese oxides (cryptomelane) sampled in the lateritic profile of each paleolandscape element have documented the weathering history and put constraints on the paleoclimatic and denudation history of Peninsular India [1,2]. The results have documented intense lateritic weathering during the Eocene (ca. 53-45 Ma) on either sides of the escarpment. Here, we present new independent constraints on the age of that weathering based on paleomagnetism of ferricretes included in thick lateritic weathering mantles of the coastal lowland plain. Our method is based on the paleomagnetic properties of Fe-oxy-hydroxides crystallized in situ in the lateritic weathering profile. The major magnetic minerals, hematite and goethite, have been analyzed by combining hysteresis and remanent magnetizations together with magnetic susceptibility measurements including thermomagnetic curves (KT curves). The main carrier of Natural Remanent Magnetization (NRM) at low temperature is a well-crystallized goethite of first generation characterized by sharp Neel temperature, Tn, at 85°C on KT curves; late goethite generations with distributed Tn below diurnal temperatures (< 65°C) are unable to keep stable NRM. At higher temperature, the component carried by primary and neoformed hematite mimics the primary goethite component. The derived paleopole fits the APWP of India at paleolatitude of 62.3° (with alpha95=5.2°) suggesting an age of ca. 52 Ma [3]. The reverse polarity systematically observed may be ascribed to Chron 23 [4] that refines the paleomagnetic age of the primary goethite to 51.9 - 52.2 Ma. This new age is in agreement with previously obtained Ar-Ar ages in the same weathering mantle upslope the pediment occupying the lowland. These results imply together that the lateritic pediment formed at the foot of the WGE is old, and further attest for very limited denudation of the coastal lowland plain confirming the great stability of the escarpment since at least 50 Ma, despite the negative anomaly of the geoid observed at this latitude. These results have major implications for the Cenozoic topographic evolution of the western continental margin of India, which underwent negligible relief rejuvenation or positive epeirogeny over the last 50 Ma. [1] Bonnet et al., 2016, Chemical Geology 446, 33-53. [2] Beauvais et al., 2016, Geology 44, 299-292. [3] Besse & Courtillot, 1991, J. Geophys. Research 96, 4029-4050 [4] Cande & Kent, 1995, Geomag. Paleomag. Mar. Geol. Geophys. 100, 6093-6095.

Long-term subsidence, cooling, and exhumation history along the South Atlantic passive continental margin in NW-Namibia

NASA Astrophysics Data System (ADS)

Menges, Daniel; Glasmacher, Ulrich Anton; Salomon, Eric; Hackspacher, Peter Christian; Schneider, Gabi

2017-04-01

In northwestern Namibia the Kaoko Belt is one of the most important Precambrian crustal segments that have stored the subsidence, cooling, and exhumation history of Namibia since the Neoproterozoic. ZFT-ages, with ages between 292.7 (46.0) and 436.8 (45.9) Ma, are giving new insights on this early evolution. Paleozoic to Mesozoic sedimentary rocks of the Karoo Supergroup and the Lower Cretaceous volcanic rocks of the Etendeka sequence overlay the Proterozoic metamorphic and intrusive rocks (1). New apatite fission-track (AFT) ages range from 390.9 (17.9) Ma to 80.8 (6.0) Ma. Along the coast apatites of Proterozoic rock samples reveal the youngest ages. Further inland the ages increase significantly. In addition, rapid change of AFT-ages occurs on both sides of major thrust and shear zones. Using the oldest thermochronological data the revealed t-T paths indicate a long era of exhumation, starting at the end of the Pan-African Orogeny in the Neoproterozoic and continuing into the Permo-Carboniferous. The subsequent sedimentation of the Karoo Supergroup initiates a new era of subsidence until the end of Triassic (2).The subsequent period of denudation ends abruptly with the rapid deposition of the Etendeka basalts in the Early Cretaceous (3). The maximum thickness of the Etendeka volcanic suite has been estimated, using the apatite fission-track data, to about 3.2 (1.2) km. With the ongoing opening of the South Atlantic and the formation of the continental margin the Kaoko Belt went through a rapid cooling event starting 130 Ma and ending 80 Ma, at a mean rate of 0.034 km/Ma for the western, and 0.018 km/Ma for the northern and eastern Kaoko Belt. This cooling event was accompanied by a reactivation of major fault zones, like the Purros Mylonite Zone (4). Thereafter, stable conditions were established, with denudation rates generally lower than 0.010 km/Ma, until the Neogene, where a second cooling event led to increased exhumation rates around 0.042 km/Ma. The total amount of denudation in the last 130 Ma has been estimated to 1.7 km in the northeastern and 3.3 km in the southwestern Kaoko Belt. References 1. Miller, R.McG. Becker, T., 2008. The Geology of Namibia: Ministry of Mines and Energy, Geological Survey (Namibia). 2. Stollhofen, H., 1999. Karoo Synrift-Sedimentation und ihre tektonische Kontrolle am entstehenden Kontinentalrand Namibias: Z.dt.geol.Ges. 149: 519-632. 3. Renne, P.R., Glen, J.M., Milner, S.C., Duncan, A.R., 1996. Age of Etendeka flood volcanism and associated intrusions in southwestern Africa: Geology 24 (7): 659- 662. 4. Salomon, E., Koehn, D., Passchier, C., 2014. Brittle reactivation of ductile shear zones in NW Namibia in relation to South Atlantic rifting: Tectonics 34, 70-85.

Resolving the chronology of the South African landscape through joint inverse modelling of AFT and apatite (U-Th)/He data

NASA Astrophysics Data System (ADS)

Wildman, Mark; Brown, Roderick; Beucher, Romain; Persano, Cristina; Stuart, Finlay

2013-04-01

Application of Low temperature thermochronometry (LTT) is a powerful method of constraining thermal history information on samples as they pass through isotherms in the upper crust. Inverse modelling of LTT data generates thermal history information which can then be correlated with independent datasets to infer geological processes that are responsible for producing the observed thermal history held in the thermochronometry record. A critical consideration when choosing which LTT method to use are the closure temperatures associated with each system. In order to generate more complete and robust thermal histories a single sample can be analysed using multiple low temperature thermochronometers that are sensitive over different but complimentary temperature ranges. The main focus of LTT work in South Africa has been on apatite fission track (AFT) analysis which is a world renowned method of constraining thermal history information between c. 60 and 110±10°C. The general conclusions that have been drawn from the South African AFT dataset is that the present day regional topography represents an eroded remnant of an elevated interior that experienced a significant uplift event with km-scale erosion in the Cretaceous following the break-up of Gondwana [1]. The exact nature of Cretaceous uplift and erosion varies both spatially and temporally, especially in south western Africa where at least two distinct denudation events are recorded at c. 130Ma and 90 Ma [2]. There are, however, alternative views suggesting significant epeirogenic-style uplift and subsequent erosion throughout the Cenozoic [3]. A key aspect of this debate which is yet to be fully resolved is the influence of mantle dynamics on the evolution of the overlying topography. To further investigate the timing and amount of Cenozoic uplift and erosion and to what degree this can be ascribed to dynamic topography, efforts have been made to complement the existing AFT record with Apatite (U-Th)/He analysis (AHe) (e.g. [4]). AHe is ideally suited to this task as it is sensitive over a lower temperature range (c. 40-75±5°C) and can therefore provide insights into erosion on the scale of 1-3 km. Correlating AFT and AHe datasets can be difficult due to variations in U and Th zonation, crystal geometry and structural defects (e.g. radiation damage) altering the closure temperature of the AHe system and resulting in significant dispersion of ages. It is therefore essential to fully understand the major cause of age dispersion and use thermal history modelling techniques that take these factors into account. Here we present a new suite of apatite (U-Th)/He data from samples along the Orange River alongside complimentary apatite fission track data from the same samples. Two samples with a large number of analysed grains, JN2 and GGO2 (23 and 21 grains, respectively) were modelled using HelFrag [5] which takes into account dispersion in AHe ages produced through analysis fragments of larger apatite grains. These modelled histories where compared with inverse modelling using QTQt [6] to extract thermal history information for each of the samples and provide new insights into the post-Cretaceous evolution of the SW African landscape and the behaviour of complex dispersion patterns commonly observed in AHe data sets. [1] Brown, R.W., Summerfield, M.A., and Gleadow, A.J.W., 2002, Denudational history along a transect across the Drakensberg Escarpment of southern Africa derived from apatite fission track thermochronology: Journal of Geophysical Research, v. 107, p. B12, 2350. [2] Kounov, A., Viola, G., de Wit, M., and Andreoli, M.A.G., 2009, Denudation along the Atlantic passive margin: new insights from apatite fission-track analysis on the western coast of South Africa: Geological Society, London, Special Publications, v. 324, p. 287-306. [3] Partridge, T.C., and Maud, R.R., 1987, Geomorphic evolution of southern Africa since the Mesozoic: South African Journal of Geology, v. 90, p. 179-208 [4] Flowers, R.M., and Schoene, B., 2010, (U-Th)/He thermochronometry constraints on unroofing of the eastern Kaapvaal craton and significance for uplift of the southern Africa Plateau: Geology, v. 38, p. 827-830. [5] Gallagher, K., 2012, Transdimensional inverse thermal history modeling for quantitative thermochronology: Journal of Geophysical Research, v. 117, p. 16. [6] Brown, R.W., Beucher, R., Roper, S., Gallagher, K., Persano, C. and Stuart, F., 2012, How to derive robust thermal histories from 'over-dispersed' single crystal apatite (U-Th)/He ages, Geophysical Research Abstracts, Vol. 14, EGU2012-11828, 2012, EGU General Assembly 2012

Annual observations of conspicuous canker activity on whitebark pine (2003 to 2007)

Treesearch

Michael P. Murray

2011-01-01

Whitebark pine's (Pinus albicaulis) notable ecological values, combined with its precarious state, underscore the need for monitoring its health and dynamics. Populations of whitebark pine are in decline throughout most of its range. White pine blister rust, caused by the fungus Cronartium ribicola, has denuded stands since introduction during the early 1900s (...

Reforestation by seed sowing in the northern Rocky Mountains

Treesearch

W. G. Wahlenberg

1925-01-01

Planting denuded forest lands with nursery stock is the dependable and established way to get new forest crops started. The fact, however, that it is in many places an operation involving heavy expenditures has led the American forester to try out other methods to a considerable extent. His characteristic discontent with established practice as such, and his constant...

Stromal Mesenchyme Cell Genes in Prostate Cancer Development: Epigenetic Markers for Cancer and Potential Targets for Therapy

DTIC Science & Technology

2006-12-01

magnetic beads (MACS) Our CD phenotyping result showed a layer of stromal cells beneath the bladder urothelium that was positive for CD13 whereas the...bladder, CD13 stains a subpopulation of stromal cells (black arrow) in the lamina propria as shown on the right. The partially denuded urothelium is

Stromal Mesenchyme Cell Genes in Prostate Cancer Development: Epigenetic Markers for Cancer and Potential Targets for Therapy

DTIC Science & Technology

2007-12-01

bladder urothelium that was positive for CD13 whereas the stromal cells next to the prostatic epithelium were not (Fig. 1). This comparative analysis was...denuded urothelium is indicated by the red arrow. Magnification is 40x. Figure 2. Distribution of differentially expressed stromal genes in bladder

Planting Loblolly Pine for Erosion Control in Northern Mississippi

Treesearch

Stanley J. Ursic

1963-01-01

Loblolly pine is widely planted for soil stabilization and the rehabilitation of denuded, actively eroding uplands of the upper Gulf Coastal Plain in north Mississippi and west Tennessee. This paper presents methods and specifications that recent research has developed for such planting. It supplements information found in Wakeley’s Planting the Southern Pines and...

Fires and forest succession in the Bitterroot Mountains of northern Idaho

Treesearch

J. A. Larsen

1929-01-01

Foresters have recently begun to seek a more intimate knowledge of the natural, successional stages by which forests regain terrain lost by extensive fires or other pronounced denuding agencies. Studies in this field lead to a closer understanding of the factors which control the distribution, composition and density of the present forest, the silvical requirements of...

Summer-time distribution of air pollutants in Sequoia National Park, California

Treesearch

Andrzej Bytnerowicz; Michael Tausz; Rocio Alonso; David Jones; Ronald Johnson; Nancy Grulke

2002-01-01

Concentrations of air pollutants were monitored during the May–November 1999 period on a network of forested sites in Sequoia National Park, California. Measurements were conducted with: (1) active monitors for nitric oxide (NO), nitrogen dioxide (NO2) and ozone (O3); (2) honeycomb denuder/filter pack systems for nitric...

Biogenic contribution to PM-2.5 ambient aerosol from radiocarbon measurements

NASA Astrophysics Data System (ADS)

Lewis, C.; Klouda, G.; Ellenson, W.

2003-04-01

Knowledge of the relative contributions of biogenic versus anthropogenic sources to ambient aerosol is of great interest in the formulation of strategies to achieve nationally mandated air quality standards. Radiocarbon (14C) measurements provide a means to quantify the biogenic fraction of any carbon-containing sample of ambient aerosol. In the absence of an impact from biomass burning (e.g., during summertime) such measurements can provide an estimate of the contribution of biogenic secondary organic aerosol, from biogenic volatile organic compound precursors. Radiocarbon results for 11.5-h PM-2.5 samples collected near Nashville, Tennessee, USA, during summer 1999 will be presented. On average the measured biogenic fraction was surprisingly large (more than half), with the average biogenic fraction for night samples being only slightly smaller than for day samples. Discussion will include (a) description of the radiocarbon methodology, (b) use of radiocarbon measurements on local vegetation and fuel samples as calibration data, (c) concurrent measurements of organic carbon and elemental carbon ambient concentrations, (d) assessment of organic aerosol sampling artifact through use of organic vapor denuders, variable face velocities, and filter extraction, and (e) comparison with published radiocarbon results obtained in Houston, Texas in a similar study. Disclaimer: This work has been funded wholly or in part by the United States Environmental Protection Agency under Interagency Agreement No. 13937923 to the National Institute of Standards and Technology, and Contract No. 68-D5-0049 to ManTech Environmental Tecnology, Inc. It has been subjected to Agency review and approved for publication.

Scaling the Teflon Peaks: Rock type and the generation of extreme relief in the glaciated western Alaska Range

USGS Publications Warehouse

Ward, Dylan J.; Anderson, Robert S.; Haeussler, Peter J.

2012-01-01

Parts of the Alaska Range (Alaska, USA) stand in prominent exception to the “glacial buzzsaw hypothesis,” which postulates that terrain raised above the ELA is rapidly denuded by glaciers. In this paper, we discuss the role of a strong contrast in rock type in the development of this exceptional terrain. Much of the range is developed on pervasively fractured flysch, with local relief of 1000–1500 m, and mean summit elevations that are similar to modern snow line elevations. In contrast, Cretaceous and Tertiary plutons of relatively intact granite support the range's tallest mountains (including Mt. McKinley, or Denali, at 6194 m), with 2500–5000 m of local relief. The high granitic peaks protrude well above modern snow lines and support many large glaciers. We focus on the plutons of the Denali massif and the Kichatna Mountains, to the west. We use field observations, satellite photos, and digital elevation data to demonstrate how exhumation of these plutons affects glacier longitudinal profiles, the glacial drainage network, and the effectiveness of periglacial processes. In strong granite, steep, smooth valley walls are maintained by detachment of rock slabs along sheeting joints. These steep walls act as low-friction surfaces (“Teflon”), efficiently shedding snow. Simple scaling calculations show that this avalanching may greatly enhance the health of the modern glaciers. We conclude that, in places such as Denali, unusual combinations of rapid tectonic uplift and great rock strength have created the highest relief in North America by enhancing glacial erosion in the valleys while preserving the peaks.

Geomorphic influences of the Little Ice Age glacial advance on selected hillslope systems in Nordfjord, Western Norway (Erdalen and Bødalen valleys)

NASA Astrophysics Data System (ADS)

Laute, Katja; Beylich, Achim A.

2010-05-01

Hillslopes in glacially formed landscapes are typically characterized by talus cones developed beneath free rock faces. Studying hillslopes as sedimentary source, storage and transfer zones as well as surface processes acting on hillslopes since the end of the deglaciation is of importance in order to gain a better understanding of the complex sedimentary source-to-sink fluxes in cold climate environments. Hillslopes function as a key component within the geomorphic process response system. Large areas of the Norwegian fjord landscapes are covered by hillslopes and are characterized by the influences of the glacial inheritance. This PhD project is part of the NFR funded SedyMONT-Norway project within the ESF TOPO-EUROPE SedyMONT (Timescales of sediment dynamics, climate and topographic change in mountain landscapes) programme. The focus of this study is on geomorphic influences of the Little Ice Age glacial advance on postglacial hillslope systems in four distinct headwater areas of the Erdalen and Bødalen valleys in the Nordfjord valley-fjord system (inner Nordfjord, Western Norway). Both valleys can be described as steep, U-shaped and glacier-fed, subarctic tributary valleys. Approximately 14% of the 49 km2 large headwater areas of Erdalen are occupied by hillslope deposits and 41% by rock surfaces; in Bødalen hillslope deposits occupy 12% and rock surfaces occupy 38% of the 42 km2 large headwater areas. The main aims of this study are (i) to analyze and compare the morphometric characteristics as well as the composition of hillslope systems inside and outside of the Little Ice Age glacial limit, (ii) to detect possible changes within the mass balances of these hillslope systems, (iii) to identify the type and intensity of currently acting hillslope processes as well as (iv) to determine possible sediment sources and delivery pathways within the headwater areas of the catchments. The process-based approach includes orthophoto- and topographical map interpretation, hillslope profile surveying, photo monitoring, geomorphological mapping as well as GIS and DEM computing. Two appropriate hillslope test sites within each headwater area are selected in order to follow the main aims of this study. The designed monitoring instrumentation of the slope test sites includes nets for collecting freshly accumulated rockfall debris, stone tracer lines for measuring surface movements, wooden sticks for monitoring of slow surface creep movements and peg lines for depth-integrated measurements of slow mass movements. In addition, remote site cameras for monitoring rapid mass movement events (avalanches, slush- and debris flows) and slope wash traps for analyzing slope wash denudation are installed and measurements of solute concentrations at small hillslope drainage creeks for investigating the role of chemical denudation are conducted. Measurements of morphometric characteristics and longitudinal profiles along the main axis of the talus cones are carried out at each test site. The manually obtained longitudinal profile data are combined with data derived from a DEM in order to generate complete longitudinal hillslope profiles reaching from the apex until the slope foot. Preliminary results show a steepening trend of the talus cones located inside the Little Ice Age glacier limit which is due to erosion during the Little Ice Age glacial advance. In addition, some of these talus cones are characterized by a recognizable more complex talus cone morphometry and composition, resulting from implementation of Little Ice Age glacier side moraines. The combination of (i) steepened talus cones and (ii) complex composition seems to increase currently acting hillslope processes which leads to a higher sediment delivery from these slopes as compared to hillslopes outside the Little Ice Age glacier limit. The implementation of moraine material but also the increased intensity of denudative processes has a recognizable influence on the mass balance of the hillslope systems inside the Little Ice Age glacier limit. Research on the complex development of hillslope systems from a postglacial to contemporary time perspective in combination with analyses of contemporary sedimentary fluxes contributes to a better understanding of hillslopes acting as source, storage and transfer zones in cold climate environments (paraglacial systems).

Thermochronometry using red TL of quartz - a feasibility study from in-situ drill-hole samples

NASA Astrophysics Data System (ADS)

Schmidt, Christoph; Zöller, Ludwig

2015-04-01

Thermochronometry - the revelation of the temperature history of rock related to subsidence or uplift and erosion - relies on methods with closure temperatures >40-70 °C, such as (U-Th-Sm)/He or fission track analysis on apatite. These methods are applicable to young and tectonically active mountain ranges, but results of calculated mean denudation rates are too imprecise for older orogens. Several studies attested the quartz luminescence signal (325 °C TL peak, OSL fast component) isothermal decay at ambient temperatures as low as 56 °C (Prokein and Wagner, 1994; Herman et al., 2010; de Sarkar et al., 2013). The so far determined closure temperatures of the quartz luminescence thermochronometry system vary between ~35 °C for the OSL fast component (Herman et al., 2010) and ~70 °C for red thermoluminescence (RTL; Tsuchiya and Fujino, 2000) and are dependent on the cooling rate and the charge trap parameters. Although featuring a favourably low closure temperature - thus allowing to study the geologically most recent temperature history -, especially quartz OSL suffers from low dose saturation, limiting the application to highly erosive orogens. Saturation doses of RTL exceed those of OSL by a factor of 10 or more (Fattahi and Stokes, 2000), what opens up new perspectives in low-temperature thermochronometry. We here present experimental results on the general suitability of RTL for thermochronometry, obtained for samples from a drilling hole in the granitic basement of the Variscan Fichtelgebirge (Franconia, Germany). The samples allowed studying the RTL signal saturation level in-situ at different ambient temperatures up to ~55 °C (at 1831 m depth). Measurements confirmed depletion of the 325 °C RTL peak for ambient temperatures >25 °C, most probably for even lower temperatures. Irradiation experiments showed that the RTL signal is not in saturation for ambient temperatures >25 °C, even for this 'old' mountain range. We could further demonstrate that the luminescence sensitivity of samples strongly increases with rising ambient temperature, opposite to the findings of Ypma and Hochman (1991) for samples from sedimentary basins. References Fattahi, M., Stokes, S., 2000. Extending the time range of luminescence dating using red TL (RTL) from volcanic quartz. Radiation Measurements 32, 479-485. Herman, F., Rhodes, E.J., Braun, J., Heiniger, L., 2010. Uniform erosion rates and relief amplitude during glacial cycles in the Southern Alps of New Zealand, as revealed from OSL-thermochronology. Earth and Planetary Science Letters 297, 183-189. Prokein, J., Wagner, G.A., 1994. Analysis of thermoluminescent glow peaks in quartz derived from the KTB-drill hole. Radiation Measurements 23, 85-94. de Sarkar, S., Mathew, G., Pande, K., Chauhan, N., Singhvi, A.K., 2013. Rapid denudation of Higher Himalaya during late Pleistocence, evidence from OSL thermochronology. Geochronometria 40, 304-310. Tsuchiya, N., Fujino, K., 2000. Evaluation of cooling history of the Quaternary Takidani pluton using thermoluminescence technique. Proceedings World Geothermal Congress, Kyushu-Tohoku, Japan. Ypma, P.J., Hochman, M.B., 1991. Thermoluminescence geothermometry - a case study of the Otway basin. APEA Journal, 312-324.

How to sow mustard in burned watersheds of southern California

Treesearch

Clark H. Gleason

1944-01-01

After the chaparral cover of the mountain watersheds in southern California is burned, damage is usually done during winter storms by increased runoff and erosion debris from the denuded area. The damage is done not only to the works of man, but to the watershed itself. Improvements that most often suffer tangible damage include water storage and diversion structures;...

(AAAR) - SEMI-CONTINUOUS DETERMINATION OF WATER-SOLUBLE PARTICULATE COMPONENTS AND THEIR GASEOUS PRECURSORS: LABORATORY AND FIELD EVALUATION OF INSTRUMENTATION BASED ON WET WALL DENUDER AND ION CHROMATOGRAPHY TECHNOLOGY

EPA Science Inventory

Research conducted by EPA at its facility in Research Triangle Park, NC and by EPA, Brigham Young University (BYU), Dionex Corporation and others during field intensive studies in California, Utah and Florida has demonstrated the capability for the semi-continuous determination o...

SEMI-CONTINUOUS DETERMINATION OF WATER-SOLUBLE PARTICULATE COMPONENTS AND THEIR GASEOUS PRECURSORS: LABORATORY AND FIELD EVALUATION OF INSTRUMENTATION BASED ON WET WALL DENUDER AND ION CHROMATOGRAPHY TECHNOLOGY

EPA Science Inventory

Research conducted by EPA at its facility in Research Triangle Park, NC and by EPA, Brigham Young University (BYU), and others during field intensive studies in California, Utah and Florida has demonstrated the capability for the semi-continuous determination of water-soluble par...

Vegetation re-establishment on a hardwood forest site denuded by brine

Treesearch

R.S. Walters; L.R. Auchmoody

1989-01-01

Brine from active oil wells seeped through the soil of a forested site in north-western Pennsylvania and killed all vegetation in its path, leaving the affected area unproductive and unsightly. After the brine source was eliminated, herbaceous plants, shrubs and forest tree seedlings became established and developed rapidly. Establishment began in the first year and by...

Trigeminal Trophic Syndrome Associated With the Use of Synthetic Marijuana.

PubMed

Khan, Fawad A; Manacheril, Rinu; Ulep, Robin; Martin, Julie E; Chimakurthy, Anil

2017-01-01

Trigeminal trophic syndrome (TTS) is an uncommon disorder of the trigeminal nerve tract and trigeminal brainstem nucleus. The syndrome is characterized by a triad of unilateral crescentic ulcers with anesthesia and paresthesias of the involved trigeminal dermatomes. A 24-year-old right-handed black female presented to our emergency department with a 4-week history of rapidly progressive painless desquamation/denudation of skin over her right face and scalp. Four weeks prior, she had been admitted to another institution for seizures and was diagnosed with seizures provoked by synthetic marijuana use. She was afebrile during her initial presentation at our institution. Dermatologic examination revealed denudation of the epidermis and partial dermis over the right frontal, parietal, and temporal scalp with associated alopecia. To our knowledge, the association of disorders of the trigeminal nerve pathway, including TTS, with the use of synthetic marijuana has not been previously reported. The long-term neurologic effects of synthetic marijuana are difficult to predict, and the pathologic underpinnings of TTS are largely unknown. Further studies dedicated to exploring the underlying molecular and cellular mechanisms may translate into effective therapies and approaches to halt and reverse the process and prevent tissue destruction and cosmetic disfigurement.

Geomorphology and its implication in urban groundwater environment: case study from Mumbai, India

NASA Astrophysics Data System (ADS)

Rani, V. R.; Pandalai, H. S.; Sajinkumar, K. S.; Pradeepkumar, A. P.

2015-06-01

Landforms of Mumbai Island have been largely modified by the urban sprawl and the demand for groundwater will increase exponentially in the future. Quality and quantity of groundwater occurrence in island are highly influenced by the geomorphic units. As this metropolis receives heavy rainfall, the area rarely faces the issue of water scarcity, nevertheless, quality always remains a question. The landforms of Mumbai Island have been shaped by a combination of fluvial, denudational and marine processes. These landforms are categorized into two broad zones on the basis of its influence in groundwater occurrence. Denudational landforms are categorized as runoff zones whereas the other two are categorized as storage zones. This classification is on the basis of occurrence and storage of groundwater. Mumbai Island is exposed to frequent sea water incursion and groundwater quality has deteriorated. The varied hydrogeological conditions prevalent in this area prevent rapid infiltration. This combined with the overextraction of groundwater resources for agriculture and industry has caused serious concern about the continued availability of potable water. This study aims at validating the geomorphic classification of the landforms with hydrogeochemistry and borehole data and it proved that geomorphology corroborates with groundwater chemistry and subsurface geology.

Ribonucleotide Reductase Inhibitors Reduce Atherosclerosis in a Double-Injury Rabbit Model

PubMed Central

Gallaugher, Laura D; Henry, Jon C; Kearns, Patrick N; Elford, Howard L; Bergdall, Valerie K; Cardounel, Arturo J

2009-01-01

Atheroproliferative disorders such as atherosclerosis are an important health problem and one of the leading causes of morbidity and mortality in the United States. Minimally invasive therapeutic procedures, including angioplasty with stent deployment, are used frequently for obstructive coronary artery disease. However, restenosis, a proliferative vascular response, is a common sequela to this procedure. The current study investigated the effect of inhibiting ribonucleotide reductase (RR), an enzyme necessary for cellular proliferation, in an attempt to ameliorate the proliferative response. Two RR inhibitors, didox and hydroxyurea, were chosen for their potent antiproliferative properties. Studies were carried out by using a double-injury rabbit model, in which endothelial denudation was followed by the administration of a high-fat diet. At 4 wk after initial endothelial denudation, the developing atherosclerotic lesion was subjected to transluminal balloon dilation to simulate clinical intervention with percutaneous transluminal angioplasty. The degree of restenosis and atheroproliferation was assessed at 8 wk. Histologic evaluation of the lesion demonstrated that treatment with didox and hydroxyurea significantly decreased lesion area and lumen loss. These results suggest that RR inhibition may be an effective new tool for the treatment of atheroproliferative disorders. PMID:20034432

Io: Mountains and crustal extension

NASA Technical Reports Server (NTRS)

Heath, M. J.

1985-01-01

It is argued that there is good reason to conclude that mountains on Io, like those on Earth, are subject to growth and decay. The decay of mountains will be assisted by the ability of SO sub 2 to rot silicate rock and by explosive escape of sub-surface SO sub 2 from aquifers (Haemus Mons is seen to be covered by bright material, presumably fallout from a SO sub 2 rich plume which had been active on the mountain flanks). On the west side of the massif at 10 degrees S, 270 degrees W a rugged surface consists of long ridges running perpendicular to the downslope direction, suggesting tectonic denudation with crustal blocks sliding down the mountain flank. Tectonic denudation may be assisted, as in the case of the Bearpaw Mountains, Montana by overloading mountain flanks with volcanic products. The surfaces of some massifs exhibit a well developed, enigmatic corrugated terrain, consisting of complex ridge systems. Ridges may bifurcate, anastomose to form closed depressions and form concentric loops. Taken together, observations of morphology, heat flux, surface deposits and styles of volcanism may point to the existence of lithosphere domains with distinct compositions and tectonic regimes.

Effects of modification of in vitro fertilization techniques on the sex ratio of the resultant bovine embryos.

PubMed

Iwata, H; Shiono, H; Kon, Y; Matsubara, K; Kimura, K; Kuwayama, T; Monji, Y

2008-05-01

The duration of sperm-oocyte co-incubation has been observed to affect the sex ratio of in vitro produced bovine embryos. The purpose of this study was to investigate some factors that may be responsible for the skewed sex ratio. The factors studied were selected combinations of the duration of co-incubation, the presence or absence of cumulus cells, and the level of hyaluronic acid (HA) in the culture medium. Experiment 1 examined the effect of selected combinations of different factors during the fertilization phase of in vitro oocyte culture. The factors were the nature of the sperm or its treatment, the duration of the sperm-oocyte co-incubation, and the level of hyaluronic acid in the culture medium. In experiment 2, the capacitation of frozen-thawed-Percoll-washed sperm (control), pre-incubated, and non-binding sperm was evaluated by the zona pellucida (ZP) binding assay and the hypo-osmotic swelling test (HOST). The purpose of experiment 3 was to determine the oocyte cleavage rate and sex ratio of the embryos (>5 cells) produced as a consequence of the 10 treatments used in experiment 1. In treatments 1-3 (experiments 1 and 3) COC were co-cultured with sperm for 1, 5 or 18 h. Polyspermic fertilization rose as the co-incubation period increased (1 h 6.5%, 5 h 15.9%, 18 h 41.8%; P<0.05), and the highest rate of normal fertilization was observed for 5h culture (73.4%; P<0.05). The sex ratio was significantly (P<0.05) skewed from the expected 50:50 towards males following 1 h (64.4%) and 5 h (67.3%) co-incubation, but was not affected by 18 h incubation (52.3%). In treatment 4, sperm was pre-incubated for 1h and cultured with COC for 5 h. Relative to control sperm, pre-incubation of sperm increased ZP binding (116 versus 180 per ZP; P<0.05) and decreased the proportion of HOST positive sperm (65.8-48.6%; P<0.05; experiment 2). Pre-incubation did not affect the rates of polyspermy, normal fertilization or the sex ratio of the embryos (experiments 1 and 3). The oocytes used in treatments 5-10 of experiments 1 and 3 were denuded prior to fertilization. Co-incubation of denuded oocytes for 1h (treatment 5) or 5h (treatment 6) resulted in levels of polyspermic fertilization similar to that for treatment 2 with significantly lower levels of normal fertilization (41.7% and 52.6%, respectively; P<0.05), and the 1h co-incubation significantly skewed (P<0.05) the proportion of male embryos to 70.0%. Denuded oocytes were fertilized for 5h with sperm unable to bind to cumulus cells (NB sperm) in treatment 7 or those that bound to cumulus cells (B) in treatment 8. These two treatments had similar rates of polyspermic, normal and non-fertilization. However, the B sperm caused the sex ratio of the embryos to be significantly skewed to males (63.9%; P<0.05). Fertilization of denuded oocytes in medium containing hyaluronic acid (0.1 mg/ml, treatment 9; 1.0 mg/ml treatment 10) significantly (P<0.05) reduced the incidence of polyspermic fertilization relative to treatments 2 and 6, and normal fertilization relative to treatment 2, but did not affect the sex ratio of the embryos. It was concluded that exposure of sperm to cumulus cells, either before fertilization of denuded oocytes or during the process of fertilization of complete COC, increased the proportion of male embryos produced by in vitro culture. It was hypothesized that this may be due to the capacitation state of the sperm, the cumulus-sperm interaction, and/or the ability of the sperm to bind to cumulus cells or oocytes.

High speed transient sampler

DOEpatents

McEwan, T.E.

1995-11-28

A high speed sampler comprises a meandered sample transmission line for transmitting an input signal, a straight strobe transmission line for transmitting a strobe signal, and a plurality of sampling gates along the transmission lines. The sampling gates comprise a four terminal diode bridge having a first strobe resistor connected from a first terminal of the bridge to the positive strobe line, a second strobe resistor coupled from the third terminal of the bridge to the negative strobe line, a tap connected to the second terminal of the bridge and to the sample transmission line, and a sample holding capacitor connected to the fourth terminal of the bridge. The resistance of the first and second strobe resistors is much higher than the signal transmission line impedance in the preferred system. This results in a sampling gate which applies a very small load on the sample transmission line and on the strobe generator. The sample holding capacitor is implemented using a smaller capacitor and a larger capacitor isolated from the smaller capacitor by resistance. The high speed sampler of the present invention is also characterized by other optimizations, including transmission line tap compensation, stepped impedance strobe line, a multi-layer physical layout, and unique strobe generator design. A plurality of banks of such samplers are controlled for concatenated or interleaved sample intervals to achieve long sample lengths or short sample spacing. 17 figs.

High speed transient sampler

DOEpatents

McEwan, Thomas E.

1995-01-01

A high speed sampler comprises a meandered sample transmission line for transmitting an input signal, a straight strobe transmission line for transmitting a strobe signal, and a plurality of sampling gates along the transmission lines. The sampling gates comprise a four terminal diode bridge having a first strobe resistor connected from a first terminal of the bridge to the positive strobe line, a second strobe resistor coupled from the third terminal of the bridge to the negative strobe line, a tap connected to the second terminal of the bridge and to the sample transmission line, and a sample holding capacitor connected to the fourth terminal of the bridge. The resistance of the first and second strobe resistors is much higher than the signal transmission line impedance in the preferred system. This results in a sampling gate which applies a very small load on the sample transmission line and on the strobe generator. The sample holding capacitor is implemented using a smaller capacitor and a larger capacitor isolated from the smaller capacitor by resistance. The high speed sampler of the present invention is also characterized by other optimizations, including transmission line tap compensation, stepped impedance strobe line, a multi-layer physical layout, and unique strobe generator design. A plurality of banks of such samplers are controlled for concatenated or interleaved sample intervals to achieve long sample lengths or short sample spacing.

Random sampling technique for ultra-fast computations of molecular opacities for exoplanet atmospheres

NASA Astrophysics Data System (ADS)

Min, M.

2017-10-01

Context. Opacities of molecules in exoplanet atmospheres rely on increasingly detailed line-lists for these molecules. The line lists available today contain for many species up to several billions of lines. Computation of the spectral line profile created by pressure and temperature broadening, the Voigt profile, of all of these lines is becoming a computational challenge. Aims: We aim to create a method to compute the Voigt profile in a way that automatically focusses the computation time into the strongest lines, while still maintaining the continuum contribution of the high number of weaker lines. Methods: Here, we outline a statistical line sampling technique that samples the Voigt profile quickly and with high accuracy. The number of samples is adjusted to the strength of the line and the local spectral line density. This automatically provides high accuracy line shapes for strong lines or lines that are spectrally isolated. The line sampling technique automatically preserves the integrated line opacity for all lines, thereby also providing the continuum opacity created by the large number of weak lines at very low computational cost. Results: The line sampling technique is tested for accuracy when computing line spectra and correlated-k tables. Extremely fast computations ( 3.5 × 105 lines per second per core on a standard current day desktop computer) with high accuracy (≤1% almost everywhere) are obtained. A detailed recipe on how to perform the computations is given.

Flow line sampler

DOEpatents

Nicholls, Colin I.

1992-07-14

An on-line product sampling apparatus and method for measuring product samples from a product stream (12) in a flow line (14) having a sampling aperture (11), includes a sampling tube (18) for containing product samples removed from flow line (14). A piston (22) removes product samples from the product stream (12) through the sampling aperture (11) and returns samples to product stream (12). A sensor (20) communicates with sample tube (18), and senses physical properties of samples while the samples are within sample tube (18). In one embodiment, sensor (20) comprises a hydrogen transient nuclear magnetic resonance sensor for measuring physical properties of hydrogen molecules.

Solid phase microextraction Arrow for the sampling of volatile amines in wastewater and atmosphere.

PubMed

Helin, Aku; Rönkkö, Tuukka; Parshintsev, Jevgeni; Hartonen, Kari; Schilling, Beat; Läubli, Thomas; Riekkola, Marja-Liisa

2015-12-24

A new method is introduced for the sampling of volatile low molecular weight alkylamines in ambient air and wastewater by utilizing a novel SPME Arrow system, which contains a larger volume of sorbent compared to a standard SPME fiber. Parameters affecting the extraction, such as coating material, need for preconcentration, sample volume, pH, stirring rate, salt addition, extraction time and temperature were carefully optimized. In addition, analysis conditions, including desorption temperature and time as well as gas chromatographic parameters, were optimized. Compared to conventional SPME fiber, the SPME Arrow had better robustness and sensitivity. Average intermediate reproducibility of the method expressed as relative standard deviation was 12% for dimethylamine and 14% for trimethylamine, and their limit of quantification 10μg/L and 0.13μg/L respectively. Working range was from limits of quantification to 500μg/L for dimethylamine and to 130μg/L for trimethylamine. Several alkylamines were qualitatively analyzed in real samples, while target compounds dimethyl- and trimethylamines were quantified. The concentrations in influent and effluent wastewater samples were almost the same (∼80μg/L for dimethylamine, 120μg/L for trimethylamine) meaning that amines pass the water purification process unchanged or they are produced at the same rate as they are removed. For the air samples, preconcentration with phosphoric acid coated denuder was required and the concentration of trimethylamine was found to be around 1ng/m(3). The developed method was compared with optimized method based on conventional SPME and advantages and disadvantages of both approaches are discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Monitoring and Assessment of Water Retention Measures in Agricultural Land

NASA Astrophysics Data System (ADS)

Výleta, Roman; Danáčová, Michaela; Škrinár, Andrej; Fencík, Róbert; Hlavčová, Kamila

2017-12-01

One of the most interesting events, from the environmental impact point of view, is the huge storm rainfall at which soil degradation processes occur. In Slovakia, agricultural areas with a higher slope have been recently increasingly denudated by water erosion processes. Areas having regular problems with muddy floods and denudation of soil particles have been currently identified. This phenomenon has long-term adverse consequences in the agricultural landscape, especially the decline in soil fertility, the influence on soil type and the reduction of depth of the soil profile. In the case of storm rainfall or long-term precipitation, soil particles are being transported and deposited at the foot of the slope, but in many cases the large amounts of sediment are transported by water in the form of muddy floods, while putting settlements and industrial zones at risk, along with contamination and clogging of watercourses and water reservoirs. These unfavourable phenomena may be prevented by appropriate management and application of technical measures, such as water level ditches, erosion-control weirs, terraces and others. The study deals with determination of the soil loss and denudation of soil particles caused by water erosion, as well as with determination of the volume of the surface runoff created by the regional torrential rains in the area of the village of Sobotište. The research is based on the analysis of flood and erosion-control measures implemented in this area. Monitoring of these level ditches for protection against muddy floods has been carried out since 2015 using UAV technology and terrestrial laser scanning. Monitoring is aimed on determination of the volume of the ditch, changes in its capacity and shape in each year. The study evaluates both the effectiveness of these measures to reduce the surface runoff as well as the amount of eroded soil particles depending on climatological conditions. The results of the research point to the good efficiency of these measures; however, in conjunction with belt crops cultivation they could form a comprehensive flood and erosion-control protection to eliminate the muddy floods and protect the settlements from surrounding slopes.

Chemical weathering and loess inputs to soils in New Zealand's Wairarapa region

NASA Astrophysics Data System (ADS)

Lukens, C. E.; Norton, K. P.

2017-12-01

Geochemical mass-balance approaches are commonly used in soils to evaluate patterns in chemical weathering. In conjuction with cosmogenic nuclide measurements of total denudation or soil production, mass-balance approaches have been used to constrain rates of chemical weathering across a variety of landscapes. Here we present geochemical data from a series of soil pits in the Wairarapa region of New Zealand's North Island, where rates of soil production equal rates of total denudation measured using 10Be at sites nearby (i.e., the landscape is in steady state). Soil density increases with depth, consistent with steady weathering over the average soil residence time. However, soil geochemistry indicates very little chemical weathering has occurred, and immobile elements (Zr, Ti, and V) are depleted in soils relative to bedrock. This is contrary to the expected observation, wherein immobile elements should be enriched in soils relative to parent bedrock as weathered mobile solutes are progressively removed from soil. Our geochemical measurements suggest contributions from an exernal source, which has a different chemical composition than the underlying bedrock. We hypothesize that loess constitutes a substantial influx of additional material, and use a mixing model to predict geochemical patterns within soil columns. We evaluate the relative contributions of several likely loess sources, including tephra from the nearby Taupo Volcanic Center, local loess deposits formed during glacial-interglacial transitions, and far-travelling Australian dust. Using an established mass-balance approach with multiple immobile elements, we calculate the fraction of mass in soils contributed by loess to be as much as 25%. Combined with 10Be-derived estimates of soil production, we calculate average loess fluxes up to 320 t/km2/yr, which are consistent with previous estimates of loess acculumation over the late Holocene. Accounting for loess input, we find that chemical weathering fluxes are remarkably low in these soils, which sit atop fractured graywacke that likely contributes very few weatherable primary minerals. The significant loess flux in this region may have important implications for estimates of total denudation and soil production, and must be accounted for to determine patterns in chemical weathering.

Meteoric 10Be/9Be ratios in marine sedimentary records: Deciphering the mixing between their marine and terrestrial sources and influence of costal trace metal fluxes

NASA Astrophysics Data System (ADS)

Wittmann, H.; von Blanckenburg, F.; Mohtadi, M.; Christl, M.; Bernhardt, A.

2017-12-01

Meteoric 10Be to stable 9Be ratios combine a cosmogenic nuclide produced in the atmosphere at a rate known from reconstructions of magnetic field strength with a stable isotope that records the present and past continental weathering and erosion flux. In seawater, the 10Be/9Be ratio provides important information on metal release from bottom sediments, called boundary exchange, and the oceanic mixing of reactive trace metals due to the inherently different sources of the two isotopes. When measured in the authigenic phase of marine sediments, the 10Be/9Be ratio allows deriving the feedbacks between erosion, weathering, and climate in the geologic past. At an ocean margin site 37°S offshore Chile, we use the 10Be/9Be ratio to trace changes in terrestrial particulate composition due to exchange with seawater. We analyzed the reactive (sequentially extracted) phase of marine surface sediments along a coast-perpendicular transect, and compared to samples from their riverine source. We find evidence for growth of authigenic rims through co-precipitation, not via reversible adsorption, that incorporate an open ocean 10Be/9Be signature from a deep water source only 30 km from the coast, thereby overprinting terrestrial riverine 10Be/9Be signatures. We show that the measured 10Be/9Be ratios in marine sediments comprise a mixture between seawater-derived and riverine-sourced phases. As 10Be/9Be ratios increase due to exchange with seawater, particulate-bound Fe concentrations increase, which we attribute to release of Fe-rich pore waters during boundary exchange in the sediment. The implications for the use of 10Be/9Be in sedimentary records for paleo-denudation flux reconstructions are that in coast-proximal sites that are neither affected by deeper water nor by narrow boundary currents, the authigenic record will be a direct recorder of terrigenous denudation of the adjacent river catchments. Hence archive location and past oceanic circulation have to be accounted for when reconstructing continental erosion and weathering, and only at open ocean sites that are fully reset by seawater global signals can be reconstructed.

Transient digitizer with displacement current samplers

DOEpatents

McEwan, T.E.

1996-05-21

A low component count, high speed sample gate, and digitizer architecture using the sample gates is based on use of a signal transmission line, a strobe transmission line and a plurality of sample gates connected to the sample transmission line at a plurality of positions. The sample gates include a strobe pickoff structure near the strobe transmission line which generates a charge displacement current in response to propagation of the strobe signal on the strobe transmission line sufficient to trigger the sample gate. The sample gate comprises a two-diode sampling bridge and is connected to a meandered signal transmission line at one end and to a charge-holding cap at the other. The common cathodes are reverse biased. A voltage step is propagated down the strobe transmission line. As the step propagates past a capacitive pickoff, displacement current i=c(dv/dT), flows into the cathodes, driving the bridge into conduction and thereby charging the charge-holding capacitor to a value related to the signal. A charge amplifier converts the charge on the charge-holding capacitor to an output voltage. The sampler is mounted on a printed circuit board, and the sample transmission line and strobe transmission line comprise coplanar microstrips formed on a surface of the substrate. Also, the strobe pickoff structure may comprise a planar pad adjacent the strobe transmission line on the printed circuit board. 16 figs.

Transient digitizer with displacement current samplers

DOEpatents

McEwan, Thomas E.

1996-01-01

A low component count, high speed sample gate, and digitizer architecture using the sample gates is based on use of a signal transmission line, a strobe transmission line and a plurality of sample gates connected to the sample transmission line at a plurality of positions. The sample gates include a strobe pickoff structure near the strobe transmission line which generates a charge displacement current in response to propagation of the strobe signal on the strobe transmission line sufficient to trigger the sample gate. The sample gate comprises a two-diode sampling bridge and is connected to a meandered signal transmission line at one end and to a charge-holding cap at the other. The common cathodes are reverse biased. A voltage step is propagated down the strobe transmission line. As the step propagates past a capacitive pickoff, displacement current i=c(dv/dT), flows into the cathodes, driving the bridge into conduction and thereby charging the charge-holding capacitor to a value related to the signal. A charge amplifier converts the charge on the charge-holding capacitor to an output voltage. The sampler is mounted on a printed circuit board, and the sample transmission line and strobe transmission line comprise coplanar microstrips formed on a surface of the substrate. Also, the strobe pickoff structure may comprise a planar pad adjacent the strobe transmission line on the printed circuit board.

CXCR3 chemokine receptor-induced chemotaxis in human airway epithelial cells: role of p38 MAPK and PI3K signaling pathways.

PubMed

Shahabuddin, Syed; Ji, Rong; Wang, Ping; Brailoiu, Eugene; Dun, Na; Yang, Yi; Aksoy, Mark O; Kelsen, Steven G

2006-07-01

Human airway epithelial cells (HAEC) constitutively express the CXC chemokine receptor CXCR3, which regulates epithelial cell movement. In diseases such as chronic obstructive pulmonary disease and asthma, characterized by denudation of the epithelial lining, epithelial cell migration may contribute to airway repair and reconstitution. This study compared the potency and efficacy of three CXCR3 ligands, I-TAC/CXCL11, IP-10/CXCL10, and Mig/CXCL9, as inducers of chemotaxis in HAEC and examined the underlying signaling pathways involved. Studies were performed in cultured HAEC from normal subjects and the 16-HBE cell line. In normal HAEC, the efficacy of I-TAC-induced chemotaxis was 349 +/- 88% (mean +/- SE) of the medium control and approximately one-half the response to epidermal growth factor, a highly potent chemoattractant. In normal HAEC, Mig, IP-10, and I-TAC induced chemotaxis with similar potency and a rank order of efficacy of I-TAC = IP-10 > Mig. Preincubation with pertussis toxin completely blocked CXCR3-induced migration. Of interest, intracellular [Ca(2+)] did not rise in response to I-TAC, IP-10, or Mig. I-TAC induced a rapid phosphorylation (5-10 min) of two of the three MAPKs, i.e., p38 and ERK1/2. Pretreatment of HAEC with the p38 inhibitor SB 20358 or the PI3K inhibitor wortmannin dose-dependently inhibited the chemotactic response to I-TAC. In contrast, the ERK1/2 inhibitor U0126 had no effect on chemotaxis. These data indicate that in HAEC, CXCR3-mediated chemotaxis involves a G protein, which activates both the p38 MAPK and PI3K pathways in a calcium-independent fashion.

Advanced Diesel Oil Fuel Processor Development

DTIC Science & Technology

1986-06-01

water exit 29 sample quencher: gas sample line inlet 30 sample quencher: gas sample line exit 31 sample quencher: cooling water inlet 32 desulfuriser ...exit line 33, 34 desulfurimer 35 heat exchanger: process gas exit (to desulfuriser ) 38 shift reactor inlet (top) 37 shift reactor: cooling air exit

Antiretroviral Drug Susceptibility Among HIV-Infected Adults Failing Antiretroviral Therapy in Rakai, Uganda

PubMed Central

Laeyendecker, Oliver; Nakigozi, Gertrude; Gallant, Joel E.; Huang, Wei; Hudelson, Sarah E.; Quinn, Thomas C.; Newell, Kevin; Serwadda, David; Gray, Ronald H.; Wawer, Maria J.; Eshleman, Susan H.

2012-01-01

Abstract We analyzed antiretroviral drug susceptibility in HIV-infected adults failing first- and second-line antiretroviral treatment (ART) in Rakai, Uganda. Samples obtained from participants at baseline (pretreatment) and at the time of failure on first-line ART and second-line ART were analyzed using genotypic and phenotypic assays for antiretroviral drug resistance. Test results were obtained from 73 samples from 38 individuals (31 baseline samples, 36 first-line failure samples, and six second-line failure samples). Four (13%) of the 31 baseline samples had mutations associated with resistance to nucleoside or nonnucleoside reverse transcriptase inhibitors (NRTIs and NNRTIs, respectively). Among the 36 first-line failure samples, 31 (86%) had NNRTI resistance mutations and 29 (81%) had lamivudine resistance mutations; only eight (22%) had other NRTI resistance mutations. None of the six individuals failing a second-line protease inhibitor (PI)-based regimen had PI resistance mutations. Six (16%) of the participants had discordant genotypic and phenotypic test results. Genotypic resistance to drugs included in first-line ART regimens was detected prior to treatment and among participants failing first-line ART. PI resistance was not detected in individuals failing second-line ART. Surveillance for transmitted and acquired drug resistance remains a priority for scale-up of ART. PMID:22443282

Advantages and challenges in automated apatite fission track counting

NASA Astrophysics Data System (ADS)

Enkelmann, E.; Ehlers, T. A.

2012-04-01

Fission track thermochronometer data are often a core element of modern tectonic and denudation studies. Soon after the development of the fission track methods interest emerged for the developed an automated counting procedure to replace the time consuming labor of counting fission tracks under the microscope. Automated track counting became feasible in recent years with increasing improvements in computer software and hardware. One such example used in this study is the commercial automated fission track counting procedure from Autoscan Systems Pty that has been highlighted through several venues. We conducted experiments that are designed to reliably and consistently test the ability of this fully automated counting system to recognize fission tracks in apatite and a muscovite external detector. Fission tracks were analyzed in samples with a step-wise increase in sample complexity. The first set of experiments used a large (mm-size) slice of Durango apatite cut parallel to the prism plane. Second, samples with 80-200 μm large apatite grains of Fish Canyon Tuff were analyzed. This second sample set is characterized by complexities often found in apatites in different rock types. In addition to the automated counting procedure, the same samples were also analyzed using conventional counting procedures. We found for all samples that the fully automated fission track counting procedure using the Autoscan System yields a larger scatter in the fission track densities measured compared to conventional (manual) track counting. This scatter typically resulted from the false identification of tracks due surface and mineralogical defects, regardless of the image filtering procedure used. Large differences between track densities analyzed with the automated counting persisted between different grains analyzed in one sample as well as between different samples. As a result of these differences a manual correction of the fully automated fission track counts is necessary for each individual surface area and grain counted. This manual correction procedure significantly increases (up to four times) the time required to analyze a sample with the automated counting procedure compared to the conventional approach.

Age classes of western white pine planting stock in relation to aspect of planting site in northern Idaho

Treesearch

W. G. Wahlenberg

1926-01-01

In the northern Rocky Mountain region there are vast areas of forest land denuded by fire, which will remain virtually unproductive for generations to come unless planted by hand with nursery-grown trees. After the first sweep of fire through the original stands of western white pine timber (Pinus monticola) on these lands, the forest in most instances started to come...

The effects of platelet lysate on maturation, fertilization and embryo development of NMRI mouse oocytes at germinal vesicle stage.

PubMed

Pazoki, Hassan; Eimani, Hussein; Farokhi, Farah; Shahverdi, Abdol-Hossein; Tahaei, Leila Sadat

2016-04-01

Improving in vitro maturation could increase the rate of pregnancy from oocytes matured in vitro. Consequently, patients will be prevented from using gonadotropin with its related side effects. In this study, the maturation medium was enriched by platelet lysate (PL), then maturation and subsequent developments were monitored. Oocytes at germinal vesicle stage with cumulus cells (cumulus-oocyte complex) and without cumulus cells (denuded oocytes) were obtained from mature female mice. The maturation medium was enriched by 5 and 10 % PL and 5 % PL + 5 % fetal bovine serum (FBS) as experimental groups; the control groups' media consisted of 5 and 10 % FBS. After 18 h, the matured oocytes were collected and, after fertilization, subsequent development was monitored. The rates of maturation, fertilization and 2-cell embryo development for the denuded oocyte groups in experimental media 5 % PL and 5 % PL + 5 % FBS were significantly higher than those of the control groups ( P < 0.05), while the results for the cumulus-oocyte complex groups were similar between the experimental groups and control groups. The results of this study indicated that platelet lysate could improve the maturation rate in the absence of granulosa cells compared to media with FBS. This extract also had positive effects on fertilization and embryo development.

Interactions of aerosols (ammonium sulfate, ammonium nitrate and ammonium chloride) and of gases (HCl, HNO 3) with fogwater

NASA Astrophysics Data System (ADS)

Ruprecht, Heidi; Sigg, Laura

The concentrations of aerosols (NH 4NO 3, (NH 4) 2SO 4 and NH 4Cl) and of gases (HCl (g), HNO 3(g), NH 3(g) were determined by denuder methods under different conditions (in the absence of fog, before, during and after fog events). At this site situated in an urban region, high concentrations of the gaseous strong acids HCl (g) and HNO 3(g) are observed. NH 4Cl and NH 4NO 3 aerosols represent a major fraction of the Cl - and NO 3- aerosols (<2.4 μm)collected by denuders. During a fog event, very high concentrations of SO 42- were found in small aerosols, which are attributed to the aqueous phase oxidation of SO 2 under the influence of high pH due to the presence of NH 3. Differences in SO 42- concentrations measured in aerosols (<2.4 μm) and in fog droplets were probably due to mass-transport limitations of the SO 2 oxidation. Ammonium sulfate aerosols represent in some cases a significant fraction of the total S present (SO 2(g) + SO 42-. Soluble aerosols and gases contribute to the composition of fogwater and are released again after fog dissipation.

Vasodilator activity of the essential oil from aerial parts of Pectis brevipedunculata and its main constituent citral in rat aorta.

PubMed

Pereira, Sharlene Lopes; Marques, André Mesquita; Sudo, Roberto Takashi; Kaplan, Maria Auxiliadora Coelho; Zapata-Sudo, Gisele

2013-03-07

The essential oil of Pectis brevipedunculata (EOPB), a Brazilian ornamental aromatic grass, is characterized by its high content of citral (81.9%: neral 32.7% and geranial 49.2%), limonene (4.7%) and α-pinene (3.4%). Vasodilation induced by EOPB and isolated citral was investigated in pre-contracted vascular smooth muscle, using thoracic aorta from Wistar Kyoto (WKY) rats which was prepared for isometric tension recording. EOPB promoted intense relaxation of endothelium-intact and denuded aortic rings with the concentration to induce 50% of the maximal relaxation (IC50) of 0.044% ± 0.006% and 0.093% ± 0.015% (p < 0.05), respectively. The IC50 values for citral in endothelium-intact and denuded rings were 0.024% ± 0.004% and 0.021% ± 0.004%, respectively (p > 0.05). In endothelium-intact aorta, EOPB-induced vasorelaxation was significantly reduced by L-NAME, a nitric oxide synthase inhibitor. The vasodilator activity of citral was increased in the KCl-contracted aorta and citral attenuated the contracture elicited by Ca2+ in depolarized aorta. EOPB and citral elicited vasorelaxation on thoracic aorta by affecting the NO/cyclic GMP pathway and the calcium influx through voltage-dependent L-type Ca2+ channels, respectively.

Vasoconstriction Potency Induced by Aminoamide Local Anesthetics Correlates with Lipid Solubility

PubMed Central

Sung, Hui-Jin; Ok, Seong-Ho; Sohn, Jin-Young; Son, Yong Hyeok; Kim, Jun Kyu; Lee, Soo Hee; Han, Jeong Yeol; Lim, Dong Hoon; Shin, Il-Woo; Lee, Heon-Keun; Chung, Young-Kyun; Choi, Mun-Jeoung; Sohn, Ju-Tae

2012-01-01

Aminoamide local anesthetics induce vasoconstriction in vivo and in vitro. The goals of this in vitro study were to investigate the potency of local anesthetic-induced vasoconstriction and to identify the physicochemical property (octanol/buffer partition coefficient, pKa, molecular weight, or potency) of local anesthetics that determines their potency in inducing isolated rat aortic ring contraction. Cumulative concentration-response curves to local anesthetics (levobupivacaine, ropivacaine, lidocaine, and mepivacaine) were obtained from isolated rat aorta. Regression analyses were performed to determine the relationship between the reported physicochemical properties of local anesthetics and the local anesthetic concentration that produced 50% (ED50) of the local anesthetic-induced maximum vasoconstriction. We determined the order of potency (ED50) of vasoconstriction among local anesthetics to be levobupivacaine > ropivacaine > lidocaine > mepivacaine. The relative importance of the independent variables that affect the vasoconstriction potency is octanol/buffer partition coefficient > potency > pKa > molecular weight. The ED50 in endothelium-denuded aorta negatively correlated with the octanol/buffer partition coefficient of local anesthetics (r2 = 0.9563; P < 0.001). The potency of the vasoconstriction in the endothelium-denuded aorta induced by local anesthetics is determined primarily by lipid solubility and, in part, by other physicochemical properties including potency and pKa. PMID:22778542

Decomposition and particle release of a carbon nanotube/epoxy nanocomposite at elevated temperatures

NASA Astrophysics Data System (ADS)

Schlagenhauf, Lukas; Kuo, Yu-Ying; Bahk, Yeon Kyoung; Nüesch, Frank; Wang, Jing

2015-11-01

Carbon nanotubes (CNTs) as fillers in nanocomposites have attracted significant attention, and one of the applications is to use the CNTs as flame retardants. For such nanocomposites, possible release of CNTs at elevated temperatures after decomposition of the polymer matrix poses potential health threats. We investigated the airborne particle release from a decomposing multi-walled carbon nanotube (MWCNT)/epoxy nanocomposite in order to measure a possible release of MWCNTs. An experimental set-up was established that allows decomposing the samples in a furnace by exposure to increasing temperatures at a constant heating rate and under ambient air or nitrogen atmosphere. The particle analysis was performed by aerosol measurement devices and by transmission electron microscopy (TEM) of collected particles. Further, by the application of a thermal denuder, it was also possible to measure non-volatile particles only. Characterization of the tested samples and the decomposition kinetics were determined by the usage of thermogravimetric analysis (TGA). The particle release of different samples was investigated, of a neat epoxy, nanocomposites with 0.1 and 1 wt% MWCNTs, and nanocomposites with functionalized MWCNTs. The results showed that the added MWCNTs had little effect on the decomposition kinetics of the investigated samples, but the weight of the remaining residues after decomposition was influenced significantly. The measurements with decomposition in different atmospheres showed a release of a higher number of particles at temperatures below 300 °C when air was used. Analysis of collected particles by TEM revealed that no detectable amount of MWCNTs was released, but micrometer-sized fibrous particles were collected.

Water quality and landscape processes of four watersheds in eastern Puerto Rico

USGS Publications Warehouse

Murphy, Sheila F.; Stallard, Robert F.; Contributions by Buss, Heather L.; Gould, William A.; Larsen, Matthew C.; Liu, Zhigang; Martinuzzi, Sebastian; Pares-Ramos, Isabel K.; White, Arthur F.; Zou, Xiaoming

2012-01-01

Humid tropical regions occupy about a quarter of Earth's land surface, yet they contribute a substantially higher fraction of the water, solutes, and sediment discharged to the world's oceans. Nearly half of Earth's population lives in the tropics, and development stresses can potentially harm soil resources, water quality, and water supply and in addition increase landslide and flood hazards. Owing to Puerto Rico's steep topography, low water storage capacity, and dependence on trade-wind precipitation, the island's people, ecosystems, and water supply are vulnerable to extreme weather such as hurricanes, floods, and droughts. Eastern Puerto Rico offers a natural laboratory for separating geologic and land-cover influences from regional- and global-scale influences because of its various bedrock types and the changing land cover surrounding intact, mature forest of the Luquillo Experimental Forest. Accordingly, a multiyear assessment of hydrological and biogeochemical processes was designed to develop an understanding of the effects of these differences on local climate, streamflow, water quality, and ecosystems, and to form the basis for a long-term and event-based program of climate and hydrologic monitoring. Because infrequent, large storms play a major role in this landscape, we focused on high-runoff events, sampling 263 storms, including all major hurricanes from 1991 through 2005. The largest storms have profound geomorphic consequences, such as landslides, debris flows, deep gullying on deforested lands, excavation and suspension of sediment in stream channels, and delivery of a substantial fraction of annual stream sediment load. Large storms sometimes entrain ocean foam and spray causing high concentrations of seasalt-derived constituents in stream waters during the storm. Past deforestation and agricultural activities in the Cayaguás and Canóvanas watersheds accelerated erosion and soil loss, and this material continues to be remobilized during large storms. Nearly 5,000 routine and event samples were analyzed for parameters that allow determination of denudation rates based on suspended and dissolved loads; 860 of these samples were analyzed for a comprehensive suite of chemical constituents. The rivers studied are generally similar in water-quality characteristics, and windward or leeward aspect appears to exert a stronger influence on water quality than geology or land cover. Of samples analyzed for comprehensive chemistry and for sediment, 543 were collected at runoff rates greater than 1 millimeter per hour, 256 at rates exceeding 10 millimeters per hour, and 3 at rates exceeding 90 millimeters per hour. Streams have rarely been sampled during events with such high runoff rates. Rates of physical and chemical weathering are especially high, and physical denudation rates, forested watersheds included, are considerably greater than is expected for a steady-state system. The elevated physical erosion drives an increased particulate organic carbon flux, one that is large, important to the carbon cycle, and sustainable, because soil-carbon regeneration is rapid. The 15-year Water, Energy, and Biogeochemical Budget dataset, which includes discharge, field parameters, suspended sediment, major cations and anions, and nutrients, is available from the U.S. Geological Survey's National Water Information System (http://waterdata.usgs.gov/nwis). The dataset provides a baseline for characterizing future environmental change and will improve our understanding of the interdependencies of land, water, and biological resources and their responses to changes in climate and land use. Because eastern Puerto Rico resembles many tropical regions in terms of geology and patterns of development, implications from this study are transferable to other tropical regions facing deforestation, rapid land-use change, and climate change.

Saprolite Formation Rates using U-series Isotopes in a Granodiorite Weathering Profile from Boulder Creek CZO (Colorado, USA)

NASA Astrophysics Data System (ADS)

Pelt, Eric; Chabaux, Francois; Mills, T. Joseph; Anderson, Suzanne P.; Foster, Melissa A.

2015-04-01

Timescales of weathering profile formation and evolution are important kinetic parameters linked to erosion, climatic, and biological processes within the critical zone. In order to understand the complex kinetics of landscape evolution, water and soil resources, along with climate change, these parameters have to be estimated for many different contexts. The Betasso catchment, within the Boulder Creek Critical Zone Observatory (BC-CZO) in Colorado, is a mountain catchment in Proterozoic granodiorite uplifted in the Laramide Orogeny ca. 50 Ma. In an exposure near the catchment divide, an approximately 1.5 m deep profile through soil and saprolite was sampled and analysed for bulk U-series disequilibria (238U-234U-230Th-226Ra) to estimate the profile weathering rate. The (234U/238U), (230Th/234U) and (226Ra/230Th) disequilibria through the entire profile are small but vary systematically with depth. In the deepest samples, values are close to equilibrium. Above this, values are progressively further from equilibrium with height in the profile, suggesting a continuous leaching of U and Ra compared to Th. The (234U/238U) disequilibria remain < 1 along the profile, suggesting no significant U addition from pore waters. Only the shallowest sample (~20 cm depth) highlights a 226Ra excess, likely resulting from vegetation cycling. In contrast, variations of Th content and (230Th/232Th) - (238U/232Th) activity ratios in the isochron diagram are huge, dividing the profile into distinct zones above and below 80 cm depth. Below 80 cm, the Th content gradually increases upward from 1.5 to 3.5 ppm suggesting a relative accumulation linked to chemical weathering. Above 80 cm, the Th content jumps to ~15 ppm with a similar increase of Th/Ti or Th/Zr ratios that clearly excludes the same process of relative accumulation. This strong shift is also observed in LREE concentrations, such as La, Ce and Nd, and in Sr isotopic composition, which suggests an external input of radiogenic material such as dust from the western Colorado deserts or eroding landscapes. For the deeper part of the profile, the strong upward decrease of the (230Th/232Th) and (238U/232Th) activity ratio without generation of strong disequilibria could suggest a long history (~0.5-1 Ma) of U leaching with a very slow saprolite development (~1 m/Ma). Such a result is in agreement with slow weathering rates deduced from modern solute chemistry of rivers, but would be much lower than 10Be denudation rates on the same profile of ~10-20 m/Ma. As the 10Be rates integrate denudation over a timescale of 40-80 ka, the apparent inconsistency between rates deduced by U-series data and Be data might suggest that erosion rates have increased during the 10Be integrating time.

Effects of post-sampling conditions on ambient carbon aerosol filter measurements

NASA Astrophysics Data System (ADS)

Dillner, Ann M.; Phuah, Chin H.; Turner, Jay R.

2009-12-01

Ambient carbonaceous material collected on quartz filters is prone to measurement artifacts due to material gained or lost during post-sampling field latency, shipping, and storage. In seventeen sampling events over a one year period, ambient PM 2.5 aerosols were collected on quartz filters (without denuders) and subjected to various filter treatments to assess the potential for and extent of artifacts. The filter treatments simulated post-sampling environments that filters may be exposed to and included: storage at 40 °C for up to 96 h, storage at -16 °C for 48 h, and storage at room temperature (˜21 °C) for 48 h. Carbon mass on the filters was measured using a thermal-optical method. The total carbon (TC), total organic carbon (TOC) and total elemental carbon (TEC) as well as carbon thermal fraction masses were obtained. Statistical analyses were performed to identify significant differences in carbon fraction concentrations between filters analyzed immediately after sampling and after being subjected to treatment. TOC and TC concentrations decreased by on average 15 ± 5% and 10 ± 4%, respectively, for filters maintained at 40 °C for 96 h but did not change for filters stored at room temperature or frozen for 48 h. TEC did not change for any of the filter treatments. The mass concentration for the organic carbon thermal fraction that evolves at the lowest temperature step (OC1) decreased with increasing storage time at 40 °C with average losses of 70 ± 7% after 96 h. Therefore, OC1 is not a stable measurement due to post-sampling conditions that may be encountered. This work demonstrates that TOC and TC can have substantial measurement artifacts on filters subjected to field latency and other non-temperature controlled post-sampling handling, compared to the carbon loadings on the filter at the end of the sampling period.

Denuded Data! Grounded Theory Using the NUDIST Computer Analysis Program: In Researching the Challenge to Teacher Self-Efficacy Posed by Students with Learning Disabilities in Australian Education.

ERIC Educational Resources Information Center

Burroughs-Lange, Sue G.; Lange, John

This paper evaluates the effects of using the NUDIST (Non-numerical, Unstructured Data Indexing, Searching and Theorising) computer program to organize coded, qualitative data. The use of the software is discussed within the context of the study for which it was used: an Australian study that aimed to develop a theoretical understanding of the…

Practical guides for seeding grass on skid roads, trails, and landings, following logging on east-side forests of Washington and Oregon.

Treesearch

J.O. Gjertson

1949-01-01

Seeding to perennial grasses is an effective method for stabilizing soil, preventing invasion by undesirable plants, and increasing forage production on ground denuded during logging. A survey in 1948 of 52 areas seeded between 1940 and 1946 found 80 percent of the seedings to be medium or better in success, and 45 percent good or very good in success. A careful check...

A meteorological study of parks and timbered areas in the western yellow-pine forests of Arizona and New Mexico

Treesearch

G. A. Pearson

1913-01-01

The object of the study, the results of which are presented here, was to determine the influence of the forest cover upon climate locally in the Southwest, in so far as this influence might be of importance in the management of timberlands and the possible afforestation of parks and denuded areas. Since the bearing upon forestry rather than upon meteorology is the...

Pharmacological Prevention and Reversion of Erectile Dysfunction After Radical Prostatectomy, by Modulation of Nitric Oxide/cGMP Pathways

DTIC Science & Technology

2009-03-01

then sacrificed, body weights obtained, and paraffin-embedded tissue sections from the skin - denuded penile shaft were subjected to Masson trichrome...responsible for vasculogenic erectile dysfunction (ED) associated with aging , smoking, diabetes, hypertension, and post-radical prostatectomy. These...Pending. PI: Gonzalez-Cadavid NF (2009). Erectile Dysfunction and Nitric Oxide Synthase in Aging . RO1 DK53069-07 (resubmission). 11/09-10/14. No

Persistence of organic carbon in heated aerosol residuals measured during Tropical Composition Cloud and Climate Coupling (TC4)

NASA Astrophysics Data System (ADS)

Thornberry, T.; Froyd, K. D.; Murphy, D. M.; Thomson, D. S.; Anderson, B. E.; Thornhill, K. L.; Winstead, E. L.

2010-05-01

The Particle Analysis by Laser Mass Spectrometry (PALMS) single particle mass spectrometer was used to analyze the composition of the nonvolatile fraction of atmospheric aerosol in a number of different environments. The mass spectra of individual particles sampled through an inlet section heated to 300°C were compared to unheated particles during flights of the NASA DC-8 aircraft during the Tropical Composition Cloud and Climate Coupling (TC4) mission. Comparisons are presented of measurements made in the marine boundary layer, the free troposphere, and the continental boundary layer over the Colombian jungle. The heated section completely removed sulfate from the aerosols except for sodium sulfate and related compounds in sea salt particles. Organic material in sea salt particles was observed to be less volatile than chlorine. Biomass burning particles were more likely to survive heating than other mixed sulfate-organic particles. For all particle types, there was a significant contribution to the residues from carbonaceous material other than elemental carbon. These results demonstrate the remaining compositional complexity of aerosol residuals that survive heating in a thermal denuder.

Evaluation of the Palutop+4 malaria rapid diagnostic test in a non-endemic setting.

PubMed

van Dijk, David P J; Gillet, Philippe; Vlieghe, Erika; Cnops, Lieselotte; van Esbroeck, Marjan; Jacobs, Jan

2009-12-12

Palutop+4 (All. Diag, Strasbourg, France), a four-band malaria rapid diagnostic test (malaria RDT) targeting the histidine-rich protein 2 (HRP-2), Plasmodium vivax-specific parasite lactate dehydrogenase (Pv-pLDH) and pan Plasmodium-specific pLDH (pan-pLDH) was evaluated in a non-endemic setting on stored whole blood samples from international travellers suspected of malaria. Microscopy corrected by PCR was the reference method. Samples include those infected by Plasmodium falciparum (n = 323), Plasmodium vivax (n = 97), Plasmodium ovale (n = 73) and Plasmodium malariae (n = 25) and 95 malaria negative samples. The sensitivities for the diagnosis of P. falciparum, P. vivax, P. malariae and P. ovale were 85.1%, 66.0%, 32.0% and 5.5%. Sensitivities increased at higher parasite densities and reached 90.0% for P. falciparum >100/microl and 83.8% for P. vivax > 500/microl. Fourteen P. falciparum samples reacted with the Pv-pLDH line, one P. vivax sample with the HRP-2 line, and respectively two and four P. ovale and P. malariae samples reacted with the HRP-2 line. Two negative samples gave a signal with the HRP-2 line. Faint and weak line intensities were observed for 129/289 (44.6%) HRP-2 lines in P. falciparum samples, for 50/64 (78.1%) Pv-pLDH lines in P. vivax samples and for 9/13 (69.2%) pan-pLDH lines in P. ovale and P. malariae samples combined. Inter-observer reliabilities for positive and negative readings were excellent for the HRP-2 and Pv-pLDH lines (overall agreement > 92.0% and kappa-values for each pair of readers >or= 0.88), and good for the pan-pLDH line (85.5% overall agreement and kappa-values >or= 0.74). Palutop+4 performed moderately for the detection of P. falciparum and P. vivax, but sensitivities were lower than those of three-band malaria RDTs.

An X-band Co2+ EPR study of Zn1-xCoxO (x=0.005-0.1) nanoparticles prepared by chemical hydrolysis methods using diethylene glycol and denaturated alcohol at 5 K

NASA Astrophysics Data System (ADS)

Misra, Sushil K.; Andronenko, S. I.; Srinivasa Rao, S.; Chess, Jordan; Punnoose, A.

2015-11-01

EPR investigations on two types of dilute magnetic semiconductor (DMS) ZnO nanoparticles doped with 0.5-10% Co2+ ions, prepared by two chemical hydrolysis methods, using: (i) diethylene glycol ((CH2CH2OH)2O) (NC-rod-like samples), and (ii) denatured ethanol (CH3CH2OH) solutions (QC-spherical samples), were carried out at X-band (9.5 GHz) at 5 K. The analysis of EPR data for NC samples revealed the presence of several types of EPR lines: (i) two types, intense and weak, of high-spin Co2+ ions in the samples with Co concentration >0.5%; (ii) surface oxygen vacancies, and (iii) a ferromagnetic resonance (FMR) line. QC samples exhibit an intense FMR line and an EPR line due to high-spin Co2+ ions. FMR line is more intense, than the corresponding line exhibited by NC samples. These EPR spectra varied for sample with different doping concentrations. The magnetic states of these samples as revealed by EPR spectra, as well as the origin of ferromagnetism DMS samples are discussed.

Rockfall susceptibility mapping of Yosemite Valley (USA) using a high-resolution digital elevation model

NASA Astrophysics Data System (ADS)

Pannatier, A.; Oppikofer, T.; Jaboyedoff, M.; Stock, G. M.

2009-04-01

In Yosemite National Park (California, USA) rockfalls from the steep valley flanks are frequent (>600 documented events in 150 years) and threaten infrastructure in this popular tourist area. This study focuses on a methodology to map the susceptibility to rockfall initiation based on a high-resolution digital elevation model (HRDEM) obtained from aerial laser scanning (1 meter cell size). This methodology is based on geometric factors derived from the HRDEM, i.e., the steepness of the topography, the presence of joints or fractures enabling either a planar or a wedge failure mechanism, and a high denudation potential. The slope angle histogram computed using standard GIS routines was simulated using Gaussian distributions, which were attributed to different parts of the topography, i.e., the cliffs, the valley flanks and the valley floor. Slopes steeper than 36° are found to form cliffs and thus potentially lead to rockfalls. A morpho-structural analysis of the HRDEM was performed in Coltop3D software to determine the major discontinuity sets that shape the topography. Kinematic analyses were made for each of these 7 discontinuity sets in order to determine the HRDEM cells that fulfil the geometric criteria for a planar or wedge failure mechanism. Most of the cliffs in Yosemite Valley enable one or both of these failure mechanisms. The denudation potential was assessed using the sloping local base level (SLBL) concept. The SLBL defines a basal erosion surface and the above lying rock masses (up to 400 m in some of the vertical cliffs) are susceptible to erosion by mass wasting. A thickness of 20 m above the SLBL surface was chosen as lower limit for the denudation potential criterion. The HRDEM cells that satisfy 1, 2 or all 3 criteria are considered having low, moderate and high susceptibility to rockfall initiation. The areas with highest susceptibility (El Capitan, Glacier Point, Yosemite Falls and Half Dome) coincide well with post-glacial talus accumulations and historic rockfall sources. Compared to previous maps of potential rockfall sources that were mainly based on the slope angle criterion, this study provides a more refined analysis of potential rockfall sources and is useful for focussing detailed field investigations on those areas with high susceptibility.

The distribution and speciation of mercury in the free troposphere of the Pacific Northwest

NASA Astrophysics Data System (ADS)

Swartzendruber, Philip C.

2009-12-01

Mercury (Hg) is a potent neurotoxin which has accumulated in aquatic ecosystems and has led to increased neurological and developmental health risks for wildlife and humans worldwide. This dissertation aims to improve our understanding of the global mercury cycle by investigating its distribution and chemistry in the free troposphere. A Hg speciation system was deployed at the summit station of Mt. Bachelor, OR (2.7 km asl) (MBO). It measured gaseous elemental mercury (GEM), reactive gaseous mercury (RGM), and particulate mercury (PHg) from May-Aug 2005. The system detected RGM up to 600 pg/m3, or 40% of the total airborne Hg. The high RGM was not due to anthropogenic emissions, but was produced in situ. The GEOS-Chem chemical transport model (CTM) was unable to reproduce the magnitude of the highest RGM concentrations using the assumed OH and ozone oxidation mechanisms. The vertical distribution of mercury in the Pacific Northwest was investigated with an aircraft campaign in 2006 during the INTEX-B campaign. Three of the eight flights observed significant enhancements of GEM and CO in the free troposphere. The enhancement ratios (0.0067 (+/-0.0027) ng/m3 /ppb) were consistent with previous observations of Asian industrial influence at MBO and in Okinawa, Japan. Backtrajectories and GEOS-Chem CTM simulations supported Asian long range transport as the source of the influence. A technique was developed to measure RGM in an aircraft. In this technique, RGM is measured by difference and simultaneously is directly collected on a denuder. The system was tested in the laboratory with an RGM proxy, (HgCl 2 at ˜500 pg/m3), and the agreement of the denuder-difference techniques was 15% (+/-13%, relative percent difference). The instrument was tested in five flights from the surface to 5 km. A linear correlation of all denuder-difference data had a slope of 0.41. RGM enhancements (200-500 pg/m3) were observed with varying relationships to ozone and water vapor which suggests that upper tropospheric influence is not a controlling factor. There was no mean vertical trend in total Hg (GEM + RGM) up to 5 km. The only factor common to all high RGM, was low aerosol scattering (<2 M/m).

Euripus Mons - Landform Evolution and Climate Constraints in Promethei Terra

NASA Astrophysics Data System (ADS)

van Gasselt, Stephan; Kim, Jungrack; Baik, Hyun-Seob

2016-04-01

The Promethei Terra region of Mars exhibits a variety of geomorphic landforms indicative of ice-assisted creep of debris and ice, similar to features and processes found at the Martian dichotomy boundary in Deuteronilus, Protonilus and Nilosyrtis Mensae. Despite only little doubt about the fact that ice played an integral role in the formation of these features, it is still disputed if these features were formed by glacial processes, requiring precipitation of ice and snow and exhibiting glacial deformation and basal sliding, or if these landforms are a product of periglacial denudation and subject to different deformation regimes. As information about past climate conditions on Mars is sparse, the proper assessment of landform types today allows to put constraints on their environmental conditions in the past. Due to limited knowledge about the internal physical and thermal structure of these landforms, it remains impossible to unambiguously determine their origin [1]. A variety of geomorphic and model-based indicators need to be taken into account when putting constraints on their history and when trying to reconstruct their evolution. For selected features on Mars it has been shown by SHARAD radar observations that the ice content might be relatively high [2], and that some of them might be composed of pure ice, protected from sublimation by a thin debris cover. One of such examples, Euripus Mons, is a 80 km remnant feature with an associated circumferential talus deposit that shows indicators for deformation by downslope movement, i.e. debris apron morphology. Recent modelling assuming glacial deformation helped to reconstruct some internal structural properties [3]. Despite these attempts, Euripus Mons shows clear geomorphic signatures of classical periglacial denudation which do not fit into the concept of glacial-only evolution. Denudation rates as well as ages are similar to those reported from other locations on Mars for which hyperarid climate conditions were proposed [4] and where no positive radar measurements could be acquired. We here report on our observations supporting a periglacial mass wasting evolution and discuss results from numerical modelling applied to the settings of Euripus Mons. References: [1] Souness & Hubbard (2012) Progr. Phys. Gegr., 36(2), 238-261; [2] Holt et al. (2008) Science, 322, 1235-1238; [3] Parsons & Holt (2015) 44th Lun. Planet. Sci. Conf., #1840 [4] van Gasselt et al. (2011) Martian Geomorphology, Geol. Soc. London, 356, 43-67.

Mélange versus forearc contributions to sedimentation and uplift, during rapid denudation of a young Banda forearc-continent collisional belt

NASA Astrophysics Data System (ADS)

Duffy, Brendan; Kalansky, Julie; Bassett, Kari; Harris, Ron; Quigley, Mark; van Hinsbergen, Douwe J. J.; Strachan, Lorna J.; Rosenthal, Yair

2017-05-01

New sedimentary geochemistry and petrographic analyses provide the most extensive sedimentary documentation yet of the rapid denudation of the young Timor orogen. The data from three basins including two widely-separated, well-dated sections of the Synorogenic Megasequence of Timor-Leste, and a re-dated DSDP 262, constrain the source and timing of detrital sediment flux during forearc-continent collision along the Timor sector of the Banda Arc. The exhumed synorogenic piggy-back basins formed above a mélange unit that developed at the expense of a weak stratigraphic horizon in the Mesozoic stratigraphy, and was exhumed to the sea floor in latest Messinian time. Following an interval of deep marine chalky marl sedimentation, an increasingly muddy sediment flux indicates that the island of Timor became emergent and shed sediment by 4.5 Ma. Comparison of exhumed sections with similar patterns in the DSDP262 chemistry suggests that the sediment source was probably located some 50-60 km distant from the basin, which is consistent with the Aileu region of Timor-Leste that shows an appropriate exhumation history. All sedimentation between 4.5 and 3.2 Ma was probably derived from a low-relief, rapidly eroding, and mudstone-dominated landscape with geochemical affinities to the Triassic-mudstone-derived synorogenic mélange. The mélange unit overlies and surrounds the Banda Terrane, and was presumably structurally emplaced by propagation of a decollement through the Triassic rocks during the collision. After 3.2 Ma, sedimentation was dominated by hard rock lithologies of the Banda Terrane, consisting of forearc cover and basement, the latter including elements of metamafic rocks and metapelites. This phase of sedimentation was accompanied by rapid uplift, which may have been partly driven by a transient imbalance between rock uplift and denudation as resistant lithologies emerged from below mélange-like mudstone. Previous work has suggested that the timing of collision in Timor-Leste and West Timor was substantially different. Our reevaluation of DSDP 262 facies migration history in the context of the re-dating presented here, favours a relatively synchronous onset of uplift in both halves of the island, but with different partitioning of strain between the foreland and hinterland in each half of the island.

Observing Muostakh Island disappear: erosion of a ground-ice-rich coast in response to summer warming and sea ice reduction on the East Siberian shelf

NASA Astrophysics Data System (ADS)

Günther, F.; Overduin, P. P.; Baranskaya, A.; Opel, T.; Grigoriev, M. N.

2013-08-01

Observations of coastline retreat using contemporary very high resolution satellite and historical aerial imagery were compared to measurements of open water fractions and summer air temperatures. We analyzed seasonal and interannual variations of thawing-induced cliff top retreat (thermo-denudation) and marine abrasion (thermo-abrasion) on Muostakh Island in the southern central Laptev Sea. The island is composed of ground-ice-rich permafrost deposits of Ice Complex type that render it particularly susceptible to erosion along the coast, resulting in land loss. Based on topographic reference measurements during field campaigns, we generated digital elevation models using stereophotogrammetry, in order to block adjust and ortho-rectify aerial photographies from 1951 and GeoEye, QuickBird, WorldView-1, and WorldView-2 imagery from 2010 to 2012 for change detection. Coastline retreat for erosive segments ranged from -13 to -585 m and was -109 ± 81 m (-1.8 ± 1.3 m a-1) on average during the historical period. Current seasonal dynamics of cliff top retreat revealed rapid thermo-denudation rates of -10.2 ± 4.5 m a-1 in mid summer and -4.1 ± 2.0 m a-1 on average during the 2010-2012 observation period. Using sea ice concentration data from the Special Sensor Microwave Imager (SSM/I) and air temperature time series from Tiksi, we calculated seasonal duration available for thermo-abrasion, expressed as open water days, and for thermo-denudation, based on thawing degree days. Geomorphometric analysis revealed that total ground ice content on Muostakh is made up of equal amounts of intrasedimentary and macro ground ice, while its vertical hourglass distribution provides favorable local preconditions for subsidence and the acceleration of coastal thermo-erosion under intensifying environmental forcings. Our results showed a~close relationship between mean summer air temperature and coastal thermo-erosion rates, in agreement with observations made for various permafrost coastlines different from East Siberian Ice Complex coasts elsewhere in the Arctic. Seasonality and recent interannual variations of coastline retreat rates suggest that the combination of macro ground ice distribution in the ground and changes in enviromental forcing generate a cyclicity in coastal thermo-erosion, that is currently increasing in frequency.

Direct seeding southern pines: history and status of a technique developed for restoring cutover forests

Treesearch

J.P. Barnett

2014-01-01

Early in the 20th century the deforestation resulting from the “golden-age of lumbering” left millions of acres of forest land in the need for reforestation. The challenge was so extreme that foresters of the early 1930s estimated that it would take 900 to 1,000 years at the then rate of planting to reforest the denuded forest land that occurred throughout the Nation....

Age-Related Alterations in Regeneration of the Urinary Bladder after Subtotal Cystectomy

DTIC Science & Technology

2013-11-01

buffer. The bladders were cut into approximately equally sized strips along the longitudinal axis. The strips were denuded of the urothelium and sub... urothelium and then were attached to tissue holds at one end and to force transducers at the other end in an organ bath system (Danish Myo Technology...of the urothelium and the bladder wall to reseal immediately after STC in old animals. This suppo- sition is consistent with the decreased PCNA

Benthic and Nektonic Studies of Winyah Bay for the Proposed Channel Deepening Project and Dredging of the Western Channel Turning Basin,

DTIC Science & Technology

1981-02-01

relaitive abundance for Dasv-atis- sab Ina Collected trami the Winyah Bay. sys tem, durine October 1930.................... 51 List of Figures (Con’t...r n e rnI lv eh 1:, i o r i,_ r tu ni t ic *----------- r;talo.uo w.’ id nabe temto recolaIini ze denuded substrates l: . yr’ -1eoey ra:nna a-illtisa

The null hypothesis: steady rates of erosion, weathering and sediment accumulation during Late Cenozoic mountain uplift and glaciation

NASA Astrophysics Data System (ADS)

Willenbring, J. K.; Jerolmack, D. J.

2015-12-01

At the largest time and space scales, the pace of erosion and chemical weathering is determined by tectonic uplift rates. Deviations from this equilibrium condition arise from the transient response of landscape denudation to climatic and tectonic perturbations, and may be long lived. We posit that the constraint of mass balance, however, makes it unlikely that such disequilibrium persists at the global scale over millions of years, as has been proposed for late Cenozoic erosion. To support this contention, we synthesize existing data for weathering fluxes, global sedimentation rates, sediment yields and tectonic motions. The records show a remarkable constancy in the pace of Earth-surface evolution over the last 10 million years. These findings provide strong support for the null hypothesis; that global rates of landscape change have remained constant over the last ten million years, despite global climate change and massive mountain building events. Two important implications are: (1) global climate change may not change global denudation rates, because the nature and sign of landscape responses are varied; and (2) tectonic and climatic perturbations are accommodated in the long term by changes in landscape form. This work undermines the hypothesis that increased weathering due to late Cenozoic mountain building or climate change was the primary agent for a decrease in global temperatures.

Suppression of Peripheral Sympathetic Activity Underlies Protease-Activated Receptor 2-Mediated Hypotension

PubMed Central

Kim, Young-Hwan; Ahn, Duck-Sun; Joeng, Ji-Hyun

2014-01-01

Protease-activated receptor (PAR)-2 is expressed in endothelial cells and vascular smooth muscle cells. It plays a crucial role in regulating blood pressure via the modulation of peripheral vascular tone. Although some reports have suggested involvement of a neurogenic mechanism in PAR-2-induced hypotension, the accurate mechanism remains to be elucidated. To examine this possibility, we investigated the effect of PAR-2 activation on smooth muscle contraction evoked by electrical field stimulation (EFS) in the superior mesenteric artery. In the present study, PAR-2 agonists suppressed neurogenic contractions evoked by EFS in endothelium-denuded superior mesenteric arterial strips but did not affect contraction elicited by the external application of noradrenaline (NA). However, thrombin, a potent PAR-1 agonist, had no effect on EFS-evoked contraction. Additionally, ω-conotoxin GVIA (CgTx), a selective N-type Ca2+ channel (ICa-N) blocker, significantly inhibited EFS-evoked contraction, and this blockade almost completely occluded the suppression of EFS-evoked contraction by PAR-2 agonists. Finally, PAR-2 agonists suppressed the EFS-evoked overflow of NA in endothelium-denuded rat superior mesenteric arterial strips and this suppression was nearly completely occluded by ω-CgTx. These results suggest that activation of PAR-2 may suppress peripheral sympathetic outflow by modulating activity of ICa-N which are located in peripheral sympathetic nerve terminals, which results in PAR-2-induced hypotension. PMID:25598663

Vegetation recovery patterns assessment at landslides caused by catastrophic earthquake: a case study in central Taiwan.

PubMed

Chou, Wen-Chieh; Lin, Wen-Tzu; Lin, Chao-Yuan

2009-05-01

The catastrophic earthquake, 7.3 on the Richter scale, occurred on September 21, 1999 in Central Taiwan. Much of standing vegetation on slopes was eliminated and massive, scattered landslides were induced at the Jou-Jou Mountain area of the Wu-Chi basin in Nantou County. We evaluated three methods for assessing landslide hazard and vegetation recovery conditions. (1) Self-organizing map (SOM) neural network coupled with fuzzy technique was used to quickly extract the landslide. (2) The NDVI-based vegetation recovery index derived from multi-temporal SPOT satellite images was used to evaluate vegetation recovery rate in the denudation sites. (3) The spatial distribution index (SDI) based on land-cover topographic location was employed to analyze vegetation recovery patterns, including the invading, surviving and mixed patterns at the Jou-Jou Mountain area. On September 27, 1999, there were 849.20 ha of landslide area extracted using the self-organizing map and fuzzy technique combined model. After six years of natural vegetation succession, the landslide has gradually restored, and vegetation recovery rate reached up to 86%. On-site observation shows that many native pioneer plants have invaded onto the denudation sites even if disturbed by several typhoons. Two native surviving plants, Arundo formosana Hack and Pinus taiwanensis Hayata, play a vital role in natural vegetation succession in this area, especially for the sites on ridgeline and steep slopes.

Oocyte glutathione and fertilisation outcome of Macaca nemestrina and Macaca fascicularis in in vivo- and in vitro-matured oocytes

PubMed Central

Curnow, E. C.; Ryan, J. P.; Saunders, D. M.; Hayes, E. S.

2010-01-01

Fertilisation and development of IVM non-human primate oocytes is limited compared with that of in vivo-matured (IVO) oocytes. The present study describes the IVM of macaque oocytes with reference to oocyte glutathione (GSH). Timing of maturation, comparison of IVM media and cysteamine (CYS) supplementation as a modulator of GSH were investigated. A significantly greater proportion of oocytes reached MII after 30 h compared with 24 h of IVM. Following insemination, IVM oocytes had a significantly lower incidence of normal fertilisation (i.e. 2PN = two pronuclei and at least one polar body) and a higher rate of abnormal fertilisation (1PN = one pronucleus and at least one polar body) compared with IVO oocytes. Immunofluorescence of 1PN zygotes identified incomplete sperm head decondensation and failure of male pronucleus formation as the principal cause of abnormal fertilisation in IVM oocytes. The IVO oocytes had significantly higher GSH content than IVM oocytes. Cumulus-denuded oocytes had significantly lower GSH following IVM compared with immature oocytes at collection. Cysteamine supplementation of the IVM medium significantly increased the GSH level of cumulus-intact oocytes and reduced the incidence of 1PN formation, but did not improve GSH levels of the denuded oocyte. Suboptimal GSH levels in macaque IVM oocytes may be related to reduced fertilisation outcomes. PMID:20591337

In vivo Molecular Imaging of Glutamate Carboxypeptidase II Expression in Re-endothelialisation after Percutaneous Balloon Denudation in a Rat Model.

PubMed

Endepols, Heike; Mottaghy, Felix M; Simsekyilmaz, Sakine; Bucerius, Jan; Vogt, Felix; Winz, Oliver; Richarz, Raphael; Krapf, Philipp; Neumaier, Bernd; Zlatopolskiy, Boris D; Morgenroth, Agnieszka

2018-05-09

The short- and long-term success of intravascular stents depends on a proper re-endothelialisation after the intervention-induced endothelial denudation. The aim of this study was to evaluate the potential of in vivo molecular imaging of glutamate carboxypeptidase II (GCPII; identical with prostate-specific membrane antigen PSMA) expression as a marker of re-endothelialisation. Fifteen Sprague Dawley rats underwent unilateral balloon angioplasty of the common carotid artery (CCA). Positron emission tomography (PET) using the GCPII-targeting tracer [ 18 F]DCFPyL was performed after 5-21 days (scan 60-120 min post injection). In two animals, the GCPII inhibitor PMPA (23 mg/kg BW) was added to the tracer solution. After PET, both CCAs were removed, dissected, and immunostained with the GCPII specific antibody YPSMA-1. Difference of GCPII expression between both CCAs was established by PCR analysis. [ 18 F]DCFPyL uptake was significantly higher in the ipsilateral compared to the contralateral CCA with an ipsi-/contralateral ratio of 1.67 ± 0.39. PMPA blocked tracer binding. The selective expression of GCPII in endothelial cells of the treated CCA was confirmed by immunohistological staining. PCR analysis verified the site-specific GCPII expression. By using a molecular imaging marker of GCPII expression, we provide the first non-invasive in vivo delineation of re-endothelialisation after angioplasty.

Oocyte glutathione and fertilisation outcome of Macaca nemestrina and Macaca fascicularis in in vivo- and in vitro-matured oocytes.

PubMed

Curnow, E C; Ryan, J P; Saunders, D M; Hayes, E S

2010-01-01

Fertilisation and development of IVM non-human primate oocytes is limited compared with that of in vivo-matured (IVO) oocytes. The present study describes the IVM of macaque oocytes with reference to oocyte glutathione (GSH). Timing of maturation, comparison of IVM media and cysteamine (CYS) supplementation as a modulator of GSH were investigated. A significantly greater proportion of oocytes reached MII after 30 h compared with 24 h of IVM. Following insemination, IVM oocytes had a significantly lower incidence of normal fertilisation (i.e. 2PN = two pronuclei and at least one polar body) and a higher rate of abnormal fertilisation (1PN = one pronucleus and at least one polar body) compared with IVO oocytes. Immunofluorescence of 1PN zygotes identified incomplete sperm head decondensation and failure of male pronucleus formation as the principal cause of abnormal fertilisation in IVM oocytes. The IVO oocytes had significantly higher GSH content than IVM oocytes. Cumulus-denuded oocytes had significantly lower GSH following IVM compared with immature oocytes at collection. Cysteamine supplementation of the IVM medium significantly increased the GSH level of cumulus-intact oocytes and reduced the incidence of 1PN formation, but did not improve GSH levels of the denuded oocyte. Suboptimal GSH levels in macaque IVM oocytes may be related to reduced fertilisation outcomes.

Mechanism of induction of fibroblast to corneal endothelial cell.

PubMed

Jiang, Yan; Fu, Wei-Cai; Zhang, Lin

2014-08-01

To explore mechanism of nduction of fibroblast to corneal endothelial cell. Rabbit conjunctiva fibroblasts were used as feeder cells, rabbit oral mucosa epithelial cells were used as seed cells, and human denuded amniotic membrane was used as carrier to establish tissue engineering corneal endothelium. The transformation effect was observed. As concentration of mitomycin C increased, cell survival rate gradually decreased, cell proliferation was obviously inhibited when concentration≥25 μg/mL; 5 days after being treated by 5 μg/mL mitomycin C, cell body was enlarged and extended without cell fusion, however after being treated by 0.5 μg/mL mitomycin C, cell body was significantly proliferated and gradually fused; after 3 weeks of culture, stratified epithelium appeared on rabbit oral mucosa epithelial cells, differentiation layers were 4-5 and were well differentiated, the morphology was similar to corneal endothelial cells; Under electron microscope, surface layer of cells were polygonal, tightly connected to another with microvilli on the border, there was hemidesmosome between basal cells and human denuded amniotic membrane. Fibroblast cells have the potential of multi-directional differentiation, effective induction can promote emergence of intercellular desmosomes between seed cells and emergence of epithelial surface microvilli, and differentiate to the corneal endothelial cell. However, clinical application still needs more research and safety evaluation. Copyright © 2014 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

Numerical simulation of the effects of dilution level, depth of inhalation, and smoke composition on nicotine vapor deposition during cigarette smoking.

PubMed

Ingebrethsen, Bradley J

2006-12-01

A numerical model of an aerosol containing vaporizable nicotine depositing to the walls of a tube was developed and applied to simulate the vapor deposition of nicotine in a denuder tube and under conditions approximating those in the respiratory tract during mainstream cigarette smoke inhalation. The numerical model was validated by comparison to data for denuder tube collection of nicotine from the smoke of three types of cigarette differing in smoke acidity and nicotine volatility. Simulations predict that the absorption of water by aerosol particles inhibits nicotine vapor deposition to tube walls, and that increased temperature, decreased tube diameter, and increased dilution enhance nicotine vapor deposition rate. The combined effect of changing these four parameters to approximate the transition from conducting to gas exchange regions of the respiratory tract was a significant net increase in predicted nicotine vapor deposition rate. Comparisons of nicotine deposition rates between conditions in the conducting airways and those in the gas exchange region were informative with regard to reported nicotine retention measurements during human smoking. Reports that vaporizable nicotine can penetrate past the conducting airways, that nicotine can be retained at near 100% efficiency from mainstream smoke, and that cigarettes with differing acidity and nicotine volatility have similar nicotine uptake rates are all shown to be consistent with the results of the model simulations.

Bone marrow-derived SP cells can contribute to the respiratory tract of mice in vivo.

PubMed

Macpherson, Heather; Keir, Pamela; Webb, Sheila; Samuel, Kay; Boyle, Shelagh; Bickmore, Wendy; Forrester, Lesley; Dorin, Julia

2005-06-01

Recent work has indicated that adult bone marrow-derived cells have the ability to contribute to both the haematopoietic system and other organs. Haematopoietic reconstitution by whole bone marrow and selected but not fully characterised cell populations have resulted in reports indicating high-level repopulation of lung epithelia. The well-characterised cells from the side population have a robust ability for haematopoietic reconstitution. We have used freshly isolated side population cells derived from ROSA26 adult bone marrow and demonstrate that despite being unable to contribute to embryos following blastocyst injection, or air liquid interface cultures or denuded tracheal xenografts, they could contribute to the tracheal epithelium in vivo. Epithelial damage is reported to be important in encouraging the recruitment of marrow-derived stem cells into non-haematopoietic organs. Here we demonstrate that mice engrafted with side population cells have donor-derived cells present in the epithelial lining of the trachea following damage and repair. Donor-derived cells were found at a frequency of 0.83%. Widefield and confocal microscopy revealed donor cells that expressed cytokeratins, indicative of cells of an epithelial nature. These results imply that SP haematopoietic stem cells from the bone marrow do not have the ability to contribute to airway epithelia themselves but require factors present in vivo to allow them to acquire characteristics of this tissue.

Potentiation of vasoconstriction and pressor response by low concentration of monomethylarsonous acid (MMA(III)).

PubMed

Lim, Kyung-Min; Shin, Yoo-Sun; Kang, Seojin; Noh, Ji-Yoon; Kim, Keunyoung; Chung, Seung-Min; Yun, Yeo-Pyo; Chung, Jin-Ho

2011-09-10

A close link between arsenic exposure and hypertension has been well-established through many epidemiological reports, yet the mechanism underlying it remains unclear. Here we report that nanomolar concentrations of monomethylarsonous acid (MMA(III)), a toxic trivalent methylated arsenic metabolite, can potentiate agonist-induced vasoconstriction and pressor responses. In freshly isolated rat aortic ring, exposure to nanomolar MMA(III) (100-500 nM) potentiated phenylephrine (PE)-induced vasoconstriction while at higher concentrations (≥2.5 μM), suppression of vasoconstriction and apoptosis of vascular smooth muscle were observed. Potentiation of agonist-induced vasoconstriction was also observed with other contractile agonists and it was retained in endothelium-denuded aortic rings, suggesting that these events are agonist-independent and smooth muscle cell dependent. Interestingly, exposure to MMA(III) resulted in increased myosin light chain phosphorylation while PE-induced Ca2+ influx was not affected, reflecting that Ca2+ sensitization is involved. In line with this, MMA(III) enhanced agonist-induced activation of small GTPase RhoA, a key contributor to Ca2+ sensitization. Of note, treatment of MMA(III) to rats induced significantly higher pressor responses in vivo, demonstrating that this event can occur in vivo indeed. We believe that RhoA-mediated Ca2+ sensitization and the resultant potentiation of vasoconstriction by MMA(III) may shed light on arsenic-associated hypertension. Copyright © 2011. Published by Elsevier Ireland Ltd.

Morphological and Behavioral Changes in the Pathogenesis of a Novel Mouse Model of Communicating Hydrocephalus

PubMed Central

McMullen, Allison B.; Baidwan, Gurlal S.; McCarthy, Ken D.

2012-01-01

The Ro1 model of hydrocephalus represents an excellent model for studying the pathogenesis of hydrocephalus due to its complete penetrance and inducibility, enabling the investigation of the earliest cellular and histological changes in hydrocephalus prior to overt pathology. Hematoxylin and eosin staining, immunofluorescence and electron microscopy were used to characterize the histopathological events of hydrocephalus in this model. Additionally, a broad battery of behavioral tests was used to investigate behavioral changes in the Ro1 model of hydrocephalus. The earliest histological changes observed in this model were ventriculomegaly and disorganization of the ependymal lining of the aqueduct of Sylvius, which occurred concomitantly. Ventriculomegaly led to thinning of the ependyma, which was associated with periventricular edema and areas of the ventricular wall void of cilia and microvilli. Ependymal denudation was subsequent to severe ventriculomegaly, suggesting that it is an effect, rather than a cause, of hydrocephalus in the Ro1 model. Additionally, there was no closure of the aqueduct of Sylvius or any blockages within the ventricular system, even with severe ventriculomegaly, suggesting that the Ro1 model represents a model of communicating hydrocephalus. Interestingly, even with severe ventriculomegaly, there were no behavioral changes, suggesting that the brain is able to compensate for the structural changes that occur in the pathogenesis of hydrocephalus if the disorder progresses at a sufficiently slow rate. PMID:22291910

High speed sampler and demultiplexer

DOEpatents

McEwan, Thomas E.

1995-01-01

A high speed sampling demultiplexer based on a plurality of sampler banks, each bank comprising a sample transmission line for transmitting an input signal, a strobe transmission line for transmitting a strobe signal, and a plurality of sampling gates at respective positions along the sample transmission line for sampling the input signal in response to the strobe signal. Strobe control circuitry is coupled to the plurality of banks, and supplies a sequence of bank strobe signals to the strobe transmission lines in each of the plurality of banks, and includes circuits for controlling the timing of the bank strobe signals among the banks of samplers. Input circuitry is included for supplying the input signal to be sampled to the plurality of sample transmission lines in the respective banks. The strobe control circuitry can repetitively strobe the plurality of banks of samplers such that the banks of samplers are cycled to create a long sample length. Second tier demultiplexing circuitry is coupled to each of the samplers in the plurality of banks. The second tier demultiplexing circuitry senses the sample taken by the corresponding sampler each time the bank in which the sampler is found is strobed. A plurality of such samples can be stored by the second tier demultiplexing circuitry for later processing. Repetitive sampling with the high speed transient sampler induces an effect known as "strobe kickout". The sample transmission lines include structures which reduce strobe kickout to acceptable levels, generally 60 dB below the signal, by absorbing the kickout pulses before the next sampling repetition.

Sample Acquisition and Handling System from a Remote Platform

NASA Technical Reports Server (NTRS)

Badescu, Mircea; Sherrit, Stewart; Jones, Jack A.

2011-01-01

A system has been developed to acquire and handle samples from a suspended remote platform. The system includes a penetrator, a penetrator deployment mechanism, and a sample handler. A gravity-driven harpoon sampler was used for the system, but other solutions can be used to supply the penetration energy, such as pyrotechnic, pressurized gas, or springs. The deployment mechanism includes a line that is attached to the penetrator, a spool for reeling in the line, and a line engagement control mechanism. The penetrator has removable tips that can collect liquid, ice, or solid samples. The handling mechanism consists of a carousel that can store a series of identical or different tips, assist in penetrator reconfiguration for multiple sample acquisition, and deliver the sample to a series of instruments for analysis. The carousel sample handling system was combined with a brassboard reeling mechanism and a penetrator with removable tips. It can attach the removable tip to the penetrator, release and retrieve the penetrator, remove the tip, and present it to multiple instrument stations. The penetrator can be remotely deployed from an aerobot, penetrate and collect the sample, and be retrieved with the sample to the aerobot. The penetrator with removable tips includes sample interrogation windows and a sample retainment spring for unconsolidated samples. The line engagement motor can be used to control the penetrator release and reeling engagement, and to evenly distribute the line on the spool by rocking between left and right ends of the spool. When the arm with the guiding ring is aligned with the spool axis, the line is free to unwind from the spool without rotating the spool. When the arm is perpendicular to the spool axis, the line can move only if the spool rotates.

Improved results of LINE-1 methylation analysis in formalin-fixed, paraffin-embedded tissues with the application of a heating step during the DNA extraction process.

PubMed

Wen, Xianyu; Jeong, Seorin; Kim, Younghoon; Bae, Jeong Mo; Cho, Nam Yun; Kim, Jung Ho; Kang, Gyeong Hoon

2017-01-01

Formalin-fixed, paraffin-embedded (FFPE) tissues are important resources for profiling DNA methylation changes and for studying a variety of diseases. However, formalin fixation introduces inter-strand crosslinking, which might cause incomplete bisulfite conversion of unmethylated cytosines, which might lead to falsely elevated measurements of methylation levels in pyrosequencing assays. Long interspersed nucleotide element-1 (LINE-1) is a major constituent of repetitive transposable DNA elements, and its methylation is referred to correlates with global DNA methylation. To identify whether formalin fixation might impact the measured values of methylation in LINE-1 repetitive elements and whether prolonged heat-induced denaturation of DNA might reduce the artificial increases in measured values caused by formalin fixation, we analyzed paired fresh-frozen (FF) and FFPE xenograft tissue samples for their methylation levels in LINE-1 using a pyrosequencing assay. To further confirm the effect of a heating step in the measurement of LINE-1 or single gene methylation levels, we analyzed FFPE tissue samples of gastric cancer and colorectal cancer for their methylation status in LINE-1 and eight single genes, respectively. Formalin fixation led to an increase in the measured values of LINE-1 methylation regardless of the duration of fixation. Prolonged heating of the DNA at 95 °C for 30 min before bisulfite conversion was found (1) to decrease the discrepancy in the measured values between the paired FF and FFPE tissue samples, (2) to decrease the standard deviation of the measured value of LINE-1 methylation levels in FFPE tissue samples of gastric cancer, and (3) to improve the performance in the measurement of single gene methylation levels in FFPE tissue samples of colorectal cancer. Formalin fixation leads to artificial increases in the measured values of LINE-1 methylation, and the application of prolonged heating of DNA samples decreases the discrepancy in the measured values of LINE-1 methylation between paired FF and FFPE tissue samples. The application of prolonged heating of DNA samples improves bisulfite conversion-based measurement of LINE-1 or single gene methylation levels in FFPE tissue samples.

Holding equine oocytes in a commercial embryo-holding medium: New perspective on holding temperature and maturation time.

PubMed

Dini, Pouya; Bogado Pascottini, Osvaldo; Ducheyne, Kaatje; Hostens, Miel; Daels, Peter

2016-09-15

In the present study, we examined the effect of holding equine oocytes in Syngro embryo holding medium (EHM) overnight at either 4 °C, 17 °C, or 22 °C to 25 °C, on the time to maturation and developmental competence. We also examined the effect of placing denuded oocyte without extruded polar body back in maturation condition on subsequent maturation rate. In experiment 1, cumulus-oocyte complexes (COCs) were recovered postmortem and placed in EHM at 22 °C to 25 °C for 18 to 20 hours (OH) or placed directly in maturation (DM). The maturation rate was assessed after 22, 24, or 28 hours of culture. After denuding cumulus cells at 22 or 24 hours, oocytes without obvious polar body were placed back into culture and reassessed at subsequent time points. At 22 hours, a higher proportion of oocytes placed in OH achieved nuclear maturation than those placed in DM (63% and 37%, respectively, P = 0.008). At 24 and 28 hours, no significant differences in the % MII stage oocytes were observed between OH and DM. The nuclear maturation rate for OH oocytes was similar at 22, 24, and 28 hours, indicating that the maximum maturation rate was reached at an earlier time than that in DM. Oocytes fertilized by intracytoplasmic sperm injection resulted in a 7.1% and 6.3% blastocyst rate for OH and DM, respectively. Denuding oocytes after 22 hours or more of culture did not have an adverse effect on the final nuclear maturation rate. After 28 hours of culture, the same nuclear maturation rate (MII) was reached for nondenuded oocytes and oocytes denuded after 22 hours of 24 hours of culture. In experiment 2, COCs were held overnight at room temperature in EHM, then placed in maturation for 20, 22, and 28 hours. Nuclear maturation rate was significantly lower at 20 hours than 22 and 28 hours of culture and was similar at 22 and 28 hours, suggesting that at least 22 hours of culture is required to reach maximal maturation rate for stored oocytes (43%, 62%, and 65% at 20, 22, and 28 hours, respectively. P < 0.001). In experiment 3, COCs were either placed directly in culture or held at 22 °C to 25 °C, 17 °C, or 4 °C overnight. After 24 hours of culture, maturation rate was similar for all groups, suggesting that COCs can be stored in conventional 4 °C transport condition or 17 °C. In preliminary studies, COCs were held at 4 °C followed by 24 hours of culture, and mature oocytes were fertilized using intracytoplasmic sperm injection. Twenty-three injected oocytes yielded four blastocysts. In conclusion, we reported that oocytes can be placed in a commercial EHM and stored overnight without a detrimental effect on maturation rates or blastocyst development. Oocytes held in holding medium require less time to reach the MII stage than oocytes placed in culture directly. Removing the cumulus cells from oocytes that have been cultured for at least 22 hours does not seem to alter the final nuclear maturation rate. Finally, we observed no detrimental effect of storing oocytes at 4 °C for up to 18 hours, and oocytes appeared to maintain developmental competence and blastocyst potential. Copyright © 2016 Elsevier Inc. All rights reserved.

Growth and erosion of mountain ranges at the northeastern margin of Tibet

NASA Astrophysics Data System (ADS)

Hetzel, Ralf; Palumbo, Luigi; Giese, Jörg; Guo, Jianming

2010-05-01

The hypothesis that mountain belts may reach a steady state, in which rock uplift is balanced by erosion, has been supported by numerous field studies and numerical models. The early evolution of mountain ranges, however, and especially the relation between fault growth and topographic response has received little attention. By using a space-for-time substitution we illustrate how active thrust faults and small, fault-bounded mountain ranges evolve into mature mountain chains that will ultimately be incorporated into the laterally growing Tibetan Plateau. At an early stage of development, when faults propagate laterally, slip rates are constant along strike [1-3]. As long as no significant topographic relief has developed, tectonic uplift is at least an order of magnitude faster than the rate of erosion [2,4]. During progressive relief growth and the establishment of drainage basins, erosion of the rising mountain ranges becomes more important, but the studied ranges are still in a pre-steady state and continue to grow both vertically and laterally [5]. During this stage the rate of erosion is linearly correlated to the mean hillslope gradient and the mean local relief, if differences in lithology or rock strength are negligible [6]. The rate of relief growth may be inferred from the difference between local erosion rates on ridge crests and catchment-wide denudation rates [7] - the latter may be taken as a surrogate for the rate of river incision. As hillslopes approach a threshold value, landsliding becomes the dominant process of mass transport and erosion rates increase non-linearly with slope. Once a steady state has been reached, the erosion rate is equal to the rate of rock uplift. A key problem is how the rate of rock uplift can be quantified in such regions, because the stochastic distribution of landslides causes the denudation rates inferred from 10Be in river sediment to be highly variable [8]. References [1] Hetzel et al. (2004). Implications of the fault scaling law for the growth of topography: Mountain ranges in the broken foreland of NE Tibet. Terra Nova 16, 157-162. [2] Hetzel et al. (2002). Low slip rates and long-term preservation of geomorphic features in Central Asia. Nature 417, 428-432. [3] Hetzel et al. (2004). Late Pleistocene/Holocene slip rate of the Zhangye thrust (Qilian Shan, China) and implications for the active growth of the northeastern Tibetan Plateau, Tectonics 23, TC6006, doi:10.1029/2004TC001653. [4] Goethals et al. (2009). Determining the impact of faulting on the rate of erosion in a low-relief landscape: A case study using in situ produced 21Ne on active normal faults in the Bishop Tuff, California. Geomorphology 103, 401-413. [5] Palumbo et al. (2009). Deciphering the rate of mountain growth during topographic presteady state: an example from the NE margin of the Tibetan Plateau. Tectonics 28, TC4017, doi:10.1029/2009TC002455. [6] Palumbo et al. (in press). Topographic and lithologic control on catchment-wide denudation rates derived from cosmogenic 10Be in two mountain ranges at the margin of NE Tibet. Geomorphology, doi:10.1016/j.geomorph.2009.11.019. [7] Meyer et al. (in press). Determining the growth rate of topographic relief using in situ-produced 10Be: A case study in the Black Forest, Germany. Earth and Planetary Science Letters. [8] Densmore et al. (2009). Spatial variations in catchment-averaged denudation rates from normal fault footwalls. Geology 37, 1139-1142.

Quantification of Absorption Due to Black and Brown Carbon from Biomass Burning and Parameterizations for Comparison to Climate Models Result

NASA Astrophysics Data System (ADS)

Pokhrel, Rudra Prasad

This dissertation examines the optical properties of fresh and aged biomass burning aerosols, parameterization of these properties, and development of new instrumentation and calibration techniques to measure aerosol optical properties. Data sets were collected from the fourth Fire Lab at Missoula Experiment (FLAME-4) that took place from October 15 to November 16, 2012. Biomass collected from the various parts of the world were burned under controlled laboratory conditions and fresh emissions from different stages of burning were measured and analyzed. Optical properties of aged aerosol under different conditions was also explored. A photoacoustic absorption spectrometer (PAS) was built and integrated with a newly designed thermal denuder to improve upon observations made during Flame-4. A novel calibration technique for the PAS was developed. Single scattering albedo (SSA) and absorption Angstrom exponent (AAE) from 12 different fuels with 41 individual burns were estimated and parameterized with modified combustion efficiency (MCE) and the ratio of elemental carbon (EC) to organic carbon (OC) mass. The EC / OC ratio has better capability to parameterize SSA and AAE than MCE. The simple linear regression model proposed in this study accurately predicts SSA during the first few hours of plume aging with the ambient data from a biomass burning event. In addition, absorption due to brown carbon (BrC) can significantly lower the SSA at 405 nm resulting in a wavelength dependence of SSA. Furthermore, smoldering dominated burns have larger AAE values while flaming dominated burns have smaller AAE values indicating a large fraction of BrC is emitted during the smoldering stage of the burn. Enhancement in BC absorption (EAbs) due to coating by absorbing and non-absorbing substances is estimated at 405 nm and 660 nm. Relatively smaller values of EAbs at 660 nm compared to 405 nm suggests lensing is a less important contributor to biomass burning aerosol absorption at lower wavelengths. Multiple burns of the same fuel produced significantly different EAbs values at 405 nm, but show good correlation with the EC/OC ratio indicating less dependency on fuel type and more dependency on burn conditions. In addition, absorption due to BrC can contribute up to 92 % of the total biomass burning aerosol absorption at 405 nm and up to 58 % of the total absorption at 532 nm. Indicating BrC absorption in biomass burning emissions is equally or more important than the absorption due to BC at short wavelengths. Furthermore, fractional absorption due to BrC shows reasonably good correlation with EC/OC ratio and AAE. Primary organic aerosol is found to be more volatile than secondary organic aerosol and it is found that the thermal denuder deployed in this study removes less organic aerosol if secondary organic aerosol is present. SSA at 532 nm remains constant during different conditions of aging while SSA at 405 nm increases under certain conditions suggesting the degradation of BrC. Decreases in AAE under the same experiment further support the proposed BrC degradation. The novel thermal denuder designed completely removes non-refractory material and can be used under higher flow rates (maximum of 5 LPM) than the most commercially available thermal denuders. The new calibration techniques proposed for the photoacousitc absorption spectrometer will reduce uncertainty during calibration compared to the conventional calibration methods.

Suitability of the line intersect method for sampling hardwood logging residues

Treesearch

A. Jeff Martin

1976-01-01

The line intersect method of sampling logging residues was tested in Appalachian hardwoods and was found to provide unbiased estimates of the volume of residue in cubic feet per acre. Thirty-two chains of sample line were established on each of sixteen 1-acre plots on cutover areas in a variety of conditions. Estimates from these samples were then compared to actual...

Authentication of M14 melanoma cell line proves misidentification of MDA‐MB‐435 breast cancer cell line

PubMed Central

Korch, Christopher; Hall, Erin M.; Dirks, Wilhelm G.; Ewing, Margaret; Faries, Mark; Varella‐Garcia, Marileila; Robinson, Steven; Storts, Douglas; Turner, Jacqueline A.; Wang, Ying; Burnett, Edward C.; Healy, Lyn; Kniss, Douglas; Neve, Richard M.; Nims, Raymond W.; Reid, Yvonne A.; Robinson, William A.

2017-01-01

A variety of analytical approaches have indicated that melanoma cell line UCLA‐SO‐M14 (M14) and breast carcinoma cell line MDA‐MB‐435 originate from a common donor. This indicates that at some point in the past, one of these cell lines became misidentified, meaning that it ceased to correspond to the reported donor and instead became falsely identified (through cross‐contamination or other means) as a cell line from a different donor. Initial studies concluded that MDA‐MB‐435 was the misidentified cell line and M14 was the authentic cell line, although contradictory evidence has been published, resulting in further confusion. To address this question, we obtained early samples of the melanoma cell line (M14), a lymphoblastoid cell line from the same donor (ML14), and donor serum preserved at the originator's institution. M14 samples were cryopreserved in December 1975, before MDA‐MB‐435 cells were established in culture. Through a series of molecular characterizations, including short tandem repeat (STR) profiling and cytogenetic analysis, we demonstrated that later samples of M14 and MDA‐MB‐435 correspond to samples of M14 frozen in 1975, to the lymphoblastoid cell line ML14, and to the melanoma donor's STR profile, sex and blood type. This work demonstrates conclusively that M14 is the authentic cell line and MDA‐MB‐435 is misidentified. With clear provenance information and authentication testing of early samples, it is possible to resolve debates regarding the origins of problematic cell lines that are widely used in cancer research. PMID:28940260

Experimental evidence regarding the pressure dependence of fission track annealing in apatite

NASA Astrophysics Data System (ADS)

Schmidt, J. S.; Lelarge, M. L. M. V.; Conceicao, R. V.; Balzaretti, N. M.

2014-03-01

The main purposes of fission track thermochronology are unravelling the thermal histories of sedimentary basins, determining uplift and denudation rates, identifying the structural evolution of orogenic belts, determining sedimentary provenance, and dating volcanic rocks. The effect of temperature on fission tracks is well known and is used to determine the thermal history; however, the effect of pressure on the stability of tracks is still under debate. The present work aims to understand the role of pressure on the annealing kinetics of apatite fission tracks. The samples of Durango apatite used in our experiments were chosen for their international recognition as a calibration standard for geological dating. Neutron irradiation of the samples, after total annealing of their spontaneous tracks, produced induced tracks with homogeneous densities and lengths. The effect of pressure associated with temperature on fission track annealing was verified by experimental procedures using a hydraulic press of 1000 t with a toroidal chamber profile. The experiments consisted of a combination of applying 2 and 4 GPa with 20,150,190,235, and 290 °C for 1 and 10 h. The annealing rate was analysed by measuring the lengths of the fission tracks after each experiment using optical microscopy. The results demonstrate that the annealing of apatite fission tracks has a pressure dependence for samples subjected to 2 and 4 GPa. However, when extrapolated to pressures of ⩽150 MPa, compatible with the normal geological context in which apatite fission track methodology is broadly used, this dependence becomes insignificant compared to the temperature effect.

Application of Raman spectroscopy for on-line monitoring of low dose blend uniformity.

PubMed

Hausman, Debra S; Cambron, R Thomas; Sakr, Adel

2005-07-14

On-line Raman spectroscopy was used to evaluate the effect of blending time on low dose, 1%, blend uniformity of azimilide dihydrochloride. An 8 qt blender was used for the experiments and instrumented with a Raman probe through the I-bar port. The blender was slowed to 6.75 rpm to better illustrate the blending process (normal speed is 25 rpm). Uniformity was reached after 20 min of blending at 6.75 rpm (135 revolutions or 5.4 min at 25 rpm). On-line Raman analysis of blend uniformity provided more benefits than traditional thief sampling and off-line analysis. On-line Raman spectroscopy enabled generating data rich blend profiles, due to the ability to collect a large number of samples during the blending process (sampling every 20s). In addition, the Raman blend profile was rapidly generated, compared to the lengthy time to complete a blend profile with thief sampling and off-line analysis. The on-line Raman blend uniformity results were also significantly correlated (p-value < 0.05) to the HPLC uniformity results of thief samples.

High speed sampler and demultiplexer

DOEpatents

McEwan, T.E.

1995-12-26

A high speed sampling demultiplexer based on a plurality of sampler banks, each bank comprising a sample transmission line for transmitting an input signal, a strobe transmission line for transmitting a strobe signal, and a plurality of sampling gates at respective positions along the sample transmission line for sampling the input signal in response to the strobe signal. Strobe control circuitry is coupled to the plurality of banks, and supplies a sequence of bank strobe signals to the strobe transmission lines in each of the plurality of banks, and includes circuits for controlling the timing of the bank strobe signals among the banks of samplers. Input circuitry is included for supplying the input signal to be sampled to the plurality of sample transmission lines in the respective banks. The strobe control circuitry can repetitively strobe the plurality of banks of samplers such that the banks of samplers are cycled to create a long sample length. Second tier demultiplexing circuitry is coupled to each of the samplers in the plurality of banks. The second tier demultiplexing circuitry senses the sample taken by the corresponding sampler each time the bank in which the sampler is found is strobed. A plurality of such samples can be stored by the second tier demultiplexing circuitry for later processing. Repetitive sampling with the high speed transient sampler induces an effect known as ``strobe kickout``. The sample transmission lines include structures which reduce strobe kickout to acceptable levels, generally 60 dB below the signal, by absorbing the kickout pulses before the next sampling repetition. 16 figs.

Mouths of the Amazon River, Brazil, South America

NASA Technical Reports Server (NTRS)

1992-01-01

In this view of the Amazon River Mouth (0.0, 51.0W), a large sediment plume can be seen expanding outward into the Atlantic Ocean. The sediment plume can be seen hugging the coast north of the delta as a result of the northwest flowing coastal Guyana Current. In recent years, the flow of the Amazon has become heavily laden with sediment as soil runoff from the denuded landscape of the interior enters the Amazon River (and other rivers) drainage system.

Comparison of Demineralized Dentin and Demineralized Freeze Dried Bone as Carriers for Enamel Matrix Proteins in a Rat Critical Size Defect

DTIC Science & Technology

2005-05-01

matrix derivative or connective tissue . Part 1: comparison of clinical parameters. J Periodontol 2003;74:1110-1125. Minabe M.: A critical review of the... connective tissue , both bone and PDL can serve as sources of progenitor cells for regeneration. Surgical techniques started to evolve with the knowledge...regeneration was Prichard in 1977. This technique involved removal of overlying gingival tissue leaving interdental bone denuded (Prichard 1977). In 1983

U.S. Army Institute of Dental Research Annual Progress Report, Fiscal Year 1982 (1 October 1981-30 September 1982)

DTIC Science & Technology

1982-10-01

WOUND HEALING PRINCIPAL INVESTIGA TOR: COL STEPHEN G. WOODYARD, DC Evaluation of Citric Acid Enhancement of Oral Soft Tissue Healing on Previously Denuded...Craniofacial Tissues . 3S162775A825 CCMBAT MAXILLOFACIAL INJURY. AA,AB,AC,AD Oral and Maxillofacial Sciences. iA OE 6022 Preventive" Dentistry Measures of...Biodegradable Materials For the Treatment of 46 Fractures and Soft Tissue Wounds in the Military Situation. 3462734A875 MEDICAL DEFENSE AGAINST CHEMICAL AGENTS

Possible rainfall reduction through reduced surface temperatures due to overgrazing

NASA Technical Reports Server (NTRS)

Otterman, J.

1975-01-01

Surface temperature reduction in terrain denuded of vegetation (as by overgrazing) is postulated to decrease air convection, reducing cloudiness and rainfall probability during weak meteorological disturbances. By reducing land-sea daytime temperature differences, the surface temperature reduction decreases daytime circulation of thermally driven local winds. The described desertification mechanism, even when limited to arid regions, high albedo soils, and weak meteorological disturbances, can be an effective rainfall reducing process in many areas including most of the Mediterranean lands.

Chemical transformations of complex mixtures relevant to atmospheric processes: Laboratory and ambient studies

NASA Astrophysics Data System (ADS)

Samy, Shahryar (Shar)

The study of atmospheric chemistry and chemical transformations, which are relevant to conditions in the ambient atmosphere require the investigation of complex mixtures. In the atmosphere, complex mixtures (e.g. diesel emissions) are continually evolving as a result of physical and chemical transformations. This dissertation examines the transformations of modern diesel emissions (DE) in a series of experiments conducted at the European Outdoor Simulation Chamber (EUPHORE) in Valencia, Spain. Experimental design challenges are addressed, and the development of a NOx removal technology (denuder) is described with results from the application of the newly developed NOx denuder in the most recent EUPHORE campaign (2006). In addition, the data from an ambient aerosol study that examines atmospheric transformation products is presented and discussed. Atmospheric transformations of DE and associated secondary organic aerosol (SOA) production, along with chemical characterization of polar organic compounds (POC) in the EUPHORE experiments, provides a valuable insight on the tranformations of modern DE in environmentally relevant atmospheres. The greatest SOA production occurred in DE with toluene addition experiments (>40%), followed by DE with HCHO (for OH radical generation) experiments. A small amount of SOA (3%) was observed for DE in dark with N2O5 (for NO3 radical production) experiments. Distinct POC formation in light versus dark experiments suggests the role of OH initiated reactions in these chamber atmospheres. A trend of increasing concentrations of dicarboxylic acids in light versus dark experiments was observed when evaluated on a compound group basis. The production of diacids (as a compound group) demonstrates a consistent indicator for photochemical transformation in relation to studies in the ambient atmosphere. The four toluene addition experiments in this study were performed at different [tol]o/[NOx]o ratios and displayed an average SOA %yield (in relation to toluene) of 5.3+/-1.6%, which is compared to past chamber studies that evaluated the impact of [tol]o/[NO x]o on SOA production in more simplified mixtures. Characterization of nitrated polycyclic aromatic hydrocarbons (NPAH, nitroarenes), which have been shown to be mutagenic and/or carcinogenic, was performed on time-intergrated samples from the EUPHORE experiments. NPAH concentrations indicated significant formation and/or degradation was taking place. An inter-experimental comparison showed that distinct gas (2-nitronaphthalene) and particle (2-nitrofluoranthene, 4-nitropyrene) phase NPAH production resulted in light versus dark experiments, and degradation most likely due to photolysis was observed for one of the most abundant NPAH (1-nitropyrene) in the ambient atmosphere. The evaluation of dark experiments in high and low NOx conditions, revealed a significantly higher concentration of gas phase NPAH (mostly due to 1-nitronaphthalene) in high NOx experiments. Electrophilic nitration on chamber surfaces or sampling media can not be ruled out as a possible mechanism for the elevated NPAH concentrations. Chapter 5 presents results from an aerosol sampling study at the Storm Peak Laboratory (SPL) (3210 MSL, 40.45° N, 106.74° W) in the winter of 2007. The unique geographical character of SPL allows for extended observations/sampling of the free tropospheric interface. Of 84 analytes included in the GC-MS method, over 50 individual water extractable POC were present at concentrations greater than 0.1 ngm-3. Diurnal averages over the sampling period revealed a higher total concentration of POC at night, 211 ngm-3 (105-265 ngm-3), versus day, 160 ngm-3 (137-205 ngm -3), which suggests a more aged nighttime aerosol character. During a snow event (Jan. 11-13, 2007), the concentrations of daytime dicarboxylic acids, which may be considered as atmospheric transformation products, were reduced. Lower actinic flux, reduced transport distance, and ice crystal scavenging may explain this variability. Further evaluation of compound ratios (e.g. diacids to monoacids/levoglucosan) and the sampling period dynamics was performed to delineate diurnal aerosol character.

Southernmost Andes and South Georgia Island, North Scotia Ridge: Zircon U-Pb and muscovite {40Ar }/{39Ar } age constraints on tectonic evolution of Southwestern Gondwanaland

NASA Astrophysics Data System (ADS)

Mukasa, Samuel B.; Dalziel, Ian W. D.

1996-11-01

Zircon U-Pb and muscovite {40Ar }/{39Ar } isotopic ages have been determined on rocks from the southernmost Andes and South Georgia Island, North Scotia Ridge, to provide absolute time constraints on the kinematic evolution of southwestern Gondwanaland, until now known mainly from stratigraphic relations. The U-Pb systematics of four zircon fractions from one sample show that proto-marginal basin magmatism in the northern Scotia arc, creating the peraluminous Darwin granite suite and submarine rhyolite sequences of the Tobifera Formation, had begun by the Middle Jurassic (164.1 ± 1.7 Ma). Seven zircon fractions from two other Darwin granites are discordant with non-linear patterns, suggesting a complex history of inheritances and Pb loss. Reference lines drawn through these points on concordia diagrams give upper intercept ages of ca. 1500 Ma, interpreted as a minimum age for the inherited zircon component. This component is believed to have been derived from sedimentary rocks in the Gondwanaland margin accretionary wedge that forms the basement of the region, or else directly from the cratonic "back stop" of that wedge. Ophiolitic remnants of the Rocas Verdes marginal basin preserved in the Larsen Harbour complex on South Georgia yield the first clear evidence that Gondwanaland fragmentation had resulted in the formation of oceanic crust in the Weddell Sea region by the Late Jurassic (150 ± 1 Ma). The geographic pattern in the observed age range of 8 to 13 million years in these ophiolitic materials, while not definitive, is in keeping with propagation of the marginal basin floor northwestward from South Georgia Island to the Sarmiento Complex in southern Chile. Rocks of the Beagle granite suite, emplaced post-tectonically within the uplifted marginal basin floor, have complex zircon U-Pb systematics with gross discordances dominated by inheritances in some samples and Pb loss in others. Of eleven samples processed, only two had sufficient amounts of zircon for multiple fractions, and only one yielded colinear points. These points lie close to the lower concordia intercept for which the age is 68.9 ± 1.0 Ma, but their upper intercept is not well known. Inasmuch as this age is similar to the {40Ar }/{39Ar } age of secondary muscovite growing in extensional fractures of pulled-apart feldspar phenocrysts in a Beagle suite granitic pluton (plateau age is 68.1 ± 0.4 Ma), we interpret the two dates as good time constraints for cooling following a period of extensional deformation probably related to the tectonic denudation of the highgrade metamorphic complex of Cordillera Darwin in Tierra del Fuego.

Comparative performance of fetal goat tongue cell line ZZ-R 127 and fetal porcine kidney cell line LFBK-αvβ6 for Foot-and-mouth disease virus isolation.

PubMed

Fukai, Katsuhiko; Morioka, Kazuki; Yamada, Manabu; Nishi, Tatsuya; Yoshida, Kazuo; Kitano, Rie; Yamazoe, Reiko; Kanno, Toru

2015-07-01

The fetal goat tongue cell line ZZ-R 127 and the fetal porcine kidney cell line LFBK-α(v)β(6) have been reported to have high sensitivity to various Foot-and-mouth disease virus (FMDV) strains. The suitability of ZZ-R 127 cells for FMDV isolation not only from epithelial suspensions but also from other clinical samples has already been confirmed in a previous study. However, to our knowledge, the suitability of LFBK-α(v)β(6) cells has not been evaluated using clinical samples other than epithelial materials. In addition, both cell lines have never been compared, in terms of use for FMDV isolation, under the same conditions. Therefore, in the current study, the virus isolation rates of both cell lines were compared using clinical samples collected from animals infected experimentally with FMDV. Viruses were successfully isolated from clinical samples other than epithelial suspensions for both cell lines. The virus isolation rates for the 2 cell lines were not significantly different. The Cohen kappa coefficients between the virus isolation results for both cell lines were significantly high. Taken together, these results confirmed the suitability of LFBK-α(v)β(6) cells for FMDV isolation from clinical samples other than epithelial suspensions. The levels of susceptibility of both cell lines to FMDV isolation were also confirmed to be almost the same. © 2015 The Author(s).

Searching for the 3.5 keV Line in the Stacked Suzaku Observations of Galaxy Clusters

NASA Technical Reports Server (NTRS)

Bulbul, Esra; Markevitch, Maxim; Foster, Adam; Miller, Eric; Bautz, Mark; Lowenstein, Mike; Randall, Scott W.; Smith, Randall K.

2016-01-01

We perform a detailed study of the stacked Suzaku observations of 47 galaxy clusters, spanning a redshift range of 0.01-0.45, to search for the unidentified 3.5 keV line. This sample provides an independent test for the previously detected line. We detect a 2sigma-significant spectral feature at 3.5 keV in the spectrum of the full sample. When the sample is divided into two subsamples (cool-core and non-cool core clusters), the cool-core subsample shows no statistically significant positive residuals at the line energy. A very weak (approx. 2sigma confidence) spectral feature at 3.5 keV is permitted by the data from the non-cool-core clusters sample. The upper limit on a neutrino decay mixing angle of sin(sup 2)(2theta) = 6.1 x 10(exp -11) from the full Suzaku sample is consistent with the previous detections in the stacked XMM-Newton sample of galaxy clusters (which had a higher statistical sensitivity to faint lines), M31, and Galactic center, at a 90% confidence level. However, the constraint from the present sample, which does not include the Perseus cluster, is in tension with previously reported line flux observed in the core of the Perseus cluster with XMM-Newton and Suzaku.

The irreversibility line of magnetically grain-aligned Hg-1212 sample - Evidences of flux line lattice melting

NASA Astrophysics Data System (ADS)

de Andrade, R., Jr.; Lanfredi, A. J. C.; Ortiz, W. A.; Leite, E. R.

1997-08-01

The irreversibility line (IL) of a magnetically grain-aligned HgBa2CaCu2O6+δ (Hg-1212) sample was determined from magnetization measurements, with the magnetic fieldH parallel to the samplec-axis. The grain-aligned sample was made by mixing powdered polycrystalline samples with epoxy resin, cured under 94 KOe at room temperature. For fields below 10 kOe the Il is well fitted by a model of flux line lattice melting due to thermal fluctuations. For higher fields the IL behavior changes to an exponential growth of Hirr with 1/T. This change is related to a corresponding alteration in the character of the vortex fluctuations leading to the melting of the flux line lattice.

The Reaction and Regeneration of Cementum in Various Pathological Conditions : (Section of Odontology).

PubMed

Stones, H H

1934-04-01

(1) The reaction of cementum and its adjoining tissues to induced pathological conditions associated with the gingival sulcus is described.(2) After subjecting the sulcus to interference, its histological appearance is compared with that of definite parodontal disease.(3) Various methods were adopted for these experiments, which were performed on monkeys.(4) Artificial pockets were produced by detaching the subgingival epithelium and underlying connective tissue from the cementum. (a) Cementum is easily removed accidentally, when scraping monkeys' teeth. (b) Reattachment of connective tissues to cementum is effected, but is usually incomplete. (c) Epithelium always firmly reunites with cementum. (d) The artificial sulcus which is usually deeper than normal does not show, microscopically, the same pathological changes as in parodontal disease.(5) In other experiments, in addition to deepening the sulcus, the cementum lining the pockets was also removed, leaving denuded dentine in contact with the connective tissue. A similar condition was achieved by another method in which a dental bur was inserted between two teeth below the gum margin. (a) The gingival epithelium is capable of forming a weak attachment to the dentine, though this does not usually occur. It always proliferates down and unites with the nearest layer of cementum. It seems to have a peculiar affinity for this tissue. (b) Underlying connective tissue does not usually unite with the dentine. When this happens it is effected by the regeneration of cementum, this new tissue being lined by new cementoblasts. (c) The width of the periodontal membrane, which was increased by the experiment, is reduced to a more normal level by deposition of new alveolar bone, and to a lesser extent by regeneration of cementum. (d) In this series of experiments the artificial pocket is permanent and somewhat resembles that of parodontal disease. This is probably due, not so much to the injury, but to its effects creating a space which forms an area of chronic stagnation.

Comprehensive Analysis of the Gas- and Particle-Phase Products of VOC Oxidation

NASA Astrophysics Data System (ADS)

Bakker-Arkema, J.; Ziemann, P. J.

2017-12-01

Controlled environmental chamber studies are important for determining atmospheric reaction mechanisms and gas and aerosol products formed in the oxidation of volatile organic compounds (VOCs). Such information is necessary for developing detailed chemical models for use in predicting the atmospheric fate of VOCs and also secondary organic aerosol (SOA) formation. However, complete characterization of atmospheric oxidation reactions, including gas- and particle-phase product yields, and reaction branching ratios, are difficult to achieve. In this work, we investigated the reactions of terminal and internal alkenes with OH radicals in the presence of NOx in an attempt to fully characterize the chemistry of these systems while minimizing and accounting for the inherent uncertainties associated with environmental chamber experiments. Gas-phase products (aldehydes formed by alkoxy radical decomposition) and particle-phase products (alkyl nitrates, β-hydroxynitrates, dihydroxynitrates, 1,4-hydroxynitrates, 1,4-hydroxycarbonyls, and dihydroxycarbonyls) formed through pathways involving addition of OH to the C=C double bond as well as H-atom abstraction were identified and quantified using a suite of analytical techniques. Particle-phase products were analyzed in real time with a thermal desorption particle beam mass spectrometer; and off-line by collection onto filters, extraction, and subsequent analysis of functional groups by derivatization-spectrophotometric methods developed in our lab. Derivatized products were also separated by liquid chromatography for molecular quantitation by UV absorbance and identification using chemical ionization-ion trap mass spectrometry. Gas phase aldehydes were analyzed off-line by collection onto Tenax and a 5-channel denuder with subsequent analysis by gas chromatography, or by collection onto DNPH-coated cartridges and subsequent analysis by liquid chromatography. The full product identification and quantitation, with careful minimization of uncertainties for the various components of the experiment and analyses, demonstrates our capability to comprehensively and accurately analyze the complex chemical composition of products formed in the oxidation of organic compounds in laboratory chamber studies.

Histologic evaluation of autogenous connective tissue and acellular dermal matrix grafts in humans.

PubMed

Cummings, Lewis C; Kaldahl, Wayne B; Allen, Edward P

2005-02-01

The clinical success of root coverage with autogenous connective tissue (CT) or acellular dermal matrix (ADM) has been well documented. However, limited histological results of CT grafts have been reported, and a case report of a human block section has been published documenting an ADM graft. The purpose of this study is to document the histological results of CT grafts, ADM grafts, and coronally advanced flaps to cover denuded roots in humans. This study included four patients previously treatment planned for extractions of three or more anterior teeth. Three teeth in each patient were selected and randomly designated to receive either a CT or ADM graft beneath a coronally advanced flap (tests) or coronally advanced flap alone (control). Six months postoperatively block section extractions were performed and the teeth processed for histologic evaluation with hematoxylin-eosin and Verhoeff's stains. Histologically, both the CT and ADM were well incorporated within the recipient tissues. New fibroblasts, vascular elements, and collagen were present throughout the ADM, while retention of the transplanted elastic fibers was apparent. No effect on the keratinization or connective tissue organization of the overlying alveolar mucosa was evident with either graft. For both materials, areas of cemental deposition were present within the root notches, the alveolar bone was essentially unaffected, and the attachments to the root surfaces were similar. Although CT and ADM have a slightly different histological appearance, both can successfully be used to cover denuded roots with similar attachments and no adverse healing.

Management of gingival recession with acellular dermal matrix graft: A clinical study

PubMed Central

Balaji, V. R.; Ramakrishnan, T.; Manikandan, D.; Lambodharan, R.; Karthikeyan, B.; Niazi, Thanvir Mohammed; Ulaganathan, G.

2016-01-01

Aims and Objectives: Obtaining root coverage has become an important part of periodontal therapy. The aims of this studyare to evaluate the clinical efficacy of acellular dermal matrix graft in the coverage of denuded roots and also to examine the change in the width of keratinized gingiva. Materials and Methods: A total of 20 sites with more than or equal to 2 mm of recession depth were taken into the study, for treatment with acellular dermal matrix graft. The clinical parameters such as recession depth, recession width, width of keratinized gingiva, probing pocket depth (PD), and clinical attachment level (CAL) were measured at the baseline, 8th week, and at the end of the study (16th week). The defects were treated with a coronally positioned pedicle graft combined with acellular dermal matrix graft. Results: Out of 20 sites treated with acellular dermal matrix graft, seven sites showed complete root coverage (100%), and the mean root coverage obtained was 73.39%. There was a statistically significant reduction in recession depth, recession width, and probing PD. There was also a statistically significant increase in width of keratinized gingiva and also gain in CAL. The postoperative results were both clinically and statistically significant (P < 0.0001). Conclusion: The results of this study were esthetically acceptable to the patients and clinically acceptable in all cases. From this study, it may be concluded that acellular dermal matrix graft is an excellent substitute for autogenous graft in coverage of denuded roots. PMID:27829749

The beneficial effects of cumulus cells and oocyte-cumulus cell gap junctions depends on oocyte maturation and fertilization methods in mice.

PubMed

Zhou, Cheng-Jie; Wu, Sha-Na; Shen, Jiang-Peng; Wang, Dong-Hui; Kong, Xiang-Wei; Lu, Angeleem; Li, Yan-Jiao; Zhou, Hong-Xia; Zhao, Yue-Fang; Liang, Cheng-Guang

2016-01-01

Cumulus cells are a group of closely associated granulosa cells that surround and nourish oocytes. Previous studies have shown that cumulus cells contribute to oocyte maturation and fertilization through gap junction communication. However, it is not known how this gap junction signaling affects in vivo versus in vitro maturation of oocytes, and their subsequent fertilization and embryonic development following insemination. Therefore, in our study, we performed mouse oocyte maturation and insemination using in vivo- or in vitro-matured oocyte-cumulus complexes (OCCs, which retain gap junctions between the cumulus cells and the oocytes), in vitro-matured, denuded oocytes co-cultured with cumulus cells (DCs, which lack gap junctions between the cumulus cells and the oocytes), and in vitro-matured, denuded oocytes without cumulus cells (DOs). Using these models, we were able to analyze the effects of gap junction signaling on oocyte maturation, fertilization, and early embryo development. We found that gap junctions were necessary for both in vivo and in vitro oocyte maturation. In addition, for oocytes matured in vivo, the presence of cumulus cells during insemination improved fertilization and blastocyst formation, and this improvement was strengthened by gap junctions. Moreover, for oocytes matured in vitro, the presence of cumulus cells during insemination improved fertilization, but not blastocyst formation, and this improvement was independent of gap junctions. Our results demonstrate, for the first time, that the beneficial effect of gap junction signaling from cumulus cells depends on oocyte maturation and fertilization methods.

Source, conveyance and fate of suspended sediments following Hurricane Irene. New England, USA

USGS Publications Warehouse

Yellen, Brian; Woodruff, Jon D.; Kratz, Laura N.; Mabee, Steven B.; Morrison, Jonathan; Martini, Anna M.

2014-01-01

Hurricane Irene passed directly over the Connecticut River valley in late August, 2011. Intense precipitation and high antecedent soil moisture resulted in record flooding, mass wasting and fluvial erosion, allowing for observations of how these rare but significant extreme events affect a landscape still responding to Pleistocene glaciation and associated sediment emplacement. Clays and silts from upland glacial deposits, once suspended in the stream network, were routed directly to the mouth of the Connecticut River, resulting in record-breaking sediment loads fifteen-times greater than predicted from the pre-existing rating curve. Denudation was particularly extensive in mountainous areas. We calculate that sediment yield during the event from the Deerfield River, a steep tributary comprising 5% of the entire Connecticut River watershed, exceeded at minimum 10–40 years of routine sediment discharge and accounted for approximately 40% of the total event sediment discharge from the Connecticut River. A series of surface sediment cores taken in floodplain ponds adjacent to the tidal section of the Connecticut River before and after the event provides insight into differences in sediment sourcing and routing for the Irene event compared to periods of more routine flooding. Relative to routine conditions, sedimentation from Irene was anomalously inorganic, fine grained, and enriched in elements commonly found in chemically immature glacial tills and glaciolacustrine material. These unique sedimentary characteristics document the crucial role played by extreme precipitation from tropical disturbances in denuding this landscape.

Source, conveyance and fate of suspended sediments following Hurricane Irene. New England, USA

NASA Astrophysics Data System (ADS)

Yellen, B.; Woodruff, J. D.; Kratz, L. N.; Mabee, S. B.; Morrison, J.; Martini, A. M.

2014-12-01

Hurricane Irene passed directly over the Connecticut River valley in late August, 2011. Intense precipitation and high antecedent soil moisture resulted in record flooding, mass wasting and fluvial erosion, allowing for observations of how these rare but significant extreme events affect a landscape still responding to Pleistocene glaciation and associated sediment emplacement. Clays and silts from upland glacial deposits, once suspended in the stream network, were routed directly to the mouth of the Connecticut River, resulting in record-breaking sediment loads fifteen-times greater than predicted from the pre-existing rating curve. Denudation was particularly extensive in mountainous areas. We calculate that sediment yield during the event from the Deerfield River, a steep tributary comprising 5% of the entire Connecticut River watershed, exceeded at minimum 10-40 years of routine sediment discharge and accounted for approximately 40% of the total event sediment discharge from the Connecticut River. A series of surface sediment cores taken in floodplain ponds adjacent to the tidal section of the Connecticut River before and after the event provides insight into differences in sediment sourcing and routing for the Irene event compared to periods of more routine flooding. Relative to routine conditions, sedimentation from Irene was anomalously inorganic, fine grained, and enriched in elements commonly found in chemically immature glacial tills and glaciolacustrine material. These unique sedimentary characteristics document the crucial role played by extreme precipitation from tropical disturbances in denuding this landscape.

Community Shifts in the Surface Microbiomes of the Coral Porites astreoides with Unusual Lesions

PubMed Central

Meyer, Julie L.; Paul, Valerie J.; Teplitski, Max

2014-01-01

Apical lesions on Porites astreoides were characterized by the appearance of a thin yellow band, which was preceded by bleaching of the coral tissues and followed by a completely denuded coral skeleton, which often harbored secondary macroalgal colonizers. These characteristics have not been previously described in Porites and do not match common Caribbean coral diseases. The lesions were observed only in warmer months and at shallow depths on the fore reef in Belize. Analysis of the microbial community composition based on the V4 hypervariable region of 16S ribosomal RNA genes revealed that the surface microbiomes associated with nonsymptomatic corals were dominated by the members of the genus Endozoicomonas, consistent with other studies. Comparison of the microbiomes of nonsymptomatic and lesioned coral colonies sampled in July and September revealed two distinct groups, inconsistently related to the disease state of the coral, but showing some temporal signal. The loss of Endozoicomonas was characteristic of lesioned corals, which also harbored potential opportunistic pathogens such as Alternaria, Stenotrophomonas, and Achromobacter. The presence of lesions in P. astreoides coincided with a decrease in the relative abundance of Endozoicomonas, rather than the appearance of specific pathogenic taxa. PMID:24937478

Tectono-thermal evolution of the southwestern Alxa Tectonic Belt, NW China: Constrained by apatite U-Pb and fission track thermochronology

NASA Astrophysics Data System (ADS)

Song, Dongfang; Glorie, Stijn; Xiao, Wenjiao; Collins, Alan S.; Gillespie, Jack; Jepson, Gilby; Li, Yongchen

2018-01-01

The Central Asian Orogenic Belt (CAOB) is regarded to have undergone multiple phases of intracontinental deformation during the Meso-Cenozoic. Located in a key position along the southern CAOB, the Alxa Tectonic Belt (ATB) connects the northernmost Tibetan Plateau with the Mongolian Plateau. In this paper we apply apatite U-Pb and fission track thermochronological studies on varieties of samples from the southwestern ATB, in order to constrain its thermal evolution. Precambrian bedrock samples yield late Ordovician-early Silurian ( 430-450 Ma) and late Permian ( 257 Ma) apatite U-Pb ages; the late Paleozoic magmatic-sedimentary samples yield relatively consistent early Permian ages from 276 to 290 Ma. These data reveal that the ATB experienced multiple Paleozoic tectono-thermal events, as the samples passed through the apatite U-Pb closure temperature ( 350-550 °C). We interpret these tectonic events to record the long-lived subduction-accretion processes of the Paleo-Asian Ocean during the formation of the southern CAOB, with possible thermal influence of the Permian Tarim mantle plume. Apatite fission track (AFT) data and thermal history modelling reveal discrete low-temperature thermal events for the ATB, inducing cooling/reheating through the AFT partial annealing zone ( 120-60 °C). During the Permian, the samples underwent rapid cooling via exhumation or denudation from deep crustal levels to temperatures < 200 °C. Subsequent thermal events in the Triassic were thought to be associated with the final amalgamation of the CAOB or the closure of the Paleotethys. During the Jurassic-Cretaceous the study area experienced heating by burial, followed by renewed cooling, which may be related with the construction and subsequent collapse of the Mongol-Okhotsk Orogeny, or the Lhasa-Eurasia collision and subsequent slab break-off. These results indicate that the ATB may have been stable after late Cretaceous in contrast to the Qilian Shan and Tianshan. Finally, our results indicate differential exhumation scenario occurred across the southwestern ATB during the Cretaceous.

Thermal history and differential exhumation across the Eastern Musgrave Province, South Australia: Insights from low-temperature thermochronology

NASA Astrophysics Data System (ADS)

Glorie, Stijn; Agostino, Kate; Dutch, Rian; Pawley, Mark; Hall, James; Danišík, Martin; Evans, Noreen J.; Collins, Alan S.

2017-04-01

Multi-method geo- and thermochronological data obtained for Palaeo- and Mesoproterozoic granitoids traversing the main structural architecture of the eastern Musgrave Province within South Australia reveal multiphase cooling histories. Apatite U-Pb dating on six samples yield consistent ages of 1075-1025 Ma, suggesting a thermal reset coinciding with mantle-derived magmatism of the greater Warakurna Large Igneous Province ( 1080-1040 Ma). Apatite fission track (AFT) analysis indicate that four discrete thermal events affected the study area, inducing cooling through the AFT partial annealing zone ( 60-120 °C), supported by apatite and zircon (U-Th-Sm)/He data. Late Neoproterozoic cooling from deep crustal levels to temperatures < 200 °C was discerned, which is thought to be related to exhumation and denudation during the Petermann Orogeny. Subsequent cooling events at 450-400 Ma (Silurian-Devonian) and 310-290 Ma (Late Carboniferous) are interpreted to represent exhumation associated with the Alice Springs Orogeny. The latter event exhumed the sampled plutons to shallow crustal depths. An additional Triassic - early Jurassic thermal event, likely recording elevated geothermal gradients at that time, was observed throughout the study area, however, more data is needed to further support this interpretation. The high sample density across the structural architecture of the study area furthermore reveals patterns of fault reactivation and resulting differential exhumation, indicating shallower exhumation levels in the centre and deeper exhumation towards the margins of the sampled transect. The observed differential exhumation patterns match with existing seismic data and fit a model of an inverted graben system for the Phanerozoic evolution of the eastern Musgraves. The results highlight a complex Phanerozoic thermal history for the eastern Musgraves and help to elucidate the poorly appreciated tectonic evolution of inland Australia. This study further demonstrates how high-density sample transects across structural architecture can assess the relative crustal level and associated preservation of the thermal history record within fault-reactivated terranes.

Evaluation of different continuous cell lines in the isolation of mumps virus by the shell vial method from clinical samples

PubMed Central

Reina, J; Ballesteros, F; Mari, M; Munar, M

2001-01-01

Aims—To compare prospectively the efficacy of the Vero, LLC-MK2, MDCK, Hep-2, and MRC-5 cell lines in the isolation of the mumps virus from clinical samples by means of the shell vial method. Methods—During an epidemic outbreak of parotiditis 48 clinical samples (saliva swabs and CSF) were studied. Two vials of the Vero, LLC-MK2, MDCK, MRC-5, and Hep-2 cell lines were inoculated with 0.2 ml of the samples by the shell vial assay. The vials were incubated at 36°C for two and five days. The vials were then fixed with acetone at -20°C for 10 minutes and stained by a monoclonal antibody against mumps virus by means of an indirect immunofluorescence assay. Results—The mumps virus was isolated from 36 samples. The Vero and LLC-MK2 cell lines showed a 100% isolation capacity, MDCK showed 77.7%, MRC-5 showed 44.4%, and Hep-2 showed 22.2%. The Vero and LLC-MK2 lines were significantly different to the other cell lines (p < 0.001). The sensitivity for the Vero and LLC-MK2 lines at two and five days of incubation was identical (100%). The values obtained in the study of the quantitative isolation capacity (positive isolation with > 5 infectious foci) were 94.4% for Vero, 97.2% for LLC-MK2, 5.5% for MDCK, 5.5% for Hep-2, and 0% for MRC-5. Conclusions—The Vero and LLC-MK2 cell lines are equally efficient at two and five days incubation for the isolation of the mumps virus from clinical samples, and the use of the shell vial method considerably shortens the time of aetiological diagnosis with higher specificity. Key Words: mumps virus • Vero cell line • LLC-MK2 cell line • MDCK cell line • Hep-2 cell line • MRC-5 cell line • isolation • shell vial PMID:11729211

Escarpment evolution on high-elevation rifted margins: Insights derived from a surface processes model that combines diffusion, advection and reaction

NASA Technical Reports Server (NTRS)

Kooi, Henk; Beaumont, Christopher

1994-01-01

Experiments with a surface processes model of large-scale (1-1000 km) long-term (1-100 m.y.) erosional denudation are used to establish the controls on the evolution of a model escarpment that is related to the rifting of a continent. The mdoel describes changes in topographic form as a result of sumultaneous short- and long-range mass transport representing hillslope (diffusive) processes and fluvial transport (advection), repsectively. Fluvial entrainment is modeled as a first-order kinetic reaction which reflects the erodibility of the substrate, and therefore the fluvial system is not necessarily carrying at capacity. One dimensional and planform models demonstrate that the principal controls on the evolution of an initially steep model escarpment are (1) antecedent topography/drainage; (2) the timesale (or equivalently a length scale) in the fluvial entrainment reaction; (3) the flexural response of the lithosphere to denudation; and (4) the relative efficiencies of the short- and long-range transport processes. When rainfall and substrate lithology are uniform, a significant amount of discharge draining over the escarpment top causes it to degrade. Only when the top of the model escarpment coincides with a drainage divide can escarpment retreat occur for these conditions. An additional requirement for retreat of a model escarpment without decline is a long reaction time scale for fluvial entrainment. This corresponds to a substrate that is hard to detach by flucial erosion, and therefore to fluvial erosion that is not transport limited. Coninuous backtilting of an escarpment due ot flexural isostatic uplift in response to denudational unloading helps maintain the scarp top as a divide. It is essntial if the escarpment gradient is to be preserved during retreat in a uniform lithology. Low flexural rigidieties propote steep and slowly retreating escarpments. For given rainfall and substrate conditions, the morphology of a retraeating model escarpment is determined by the ratio of hte short-range diffusive and long range advective transport efficiencies. A low ration (which is interpreted to correspond to a more humid, temperate climate) produces a convex upper slope, and concave lower slope morphology and only major escarpments are predicted to preserve a high scarp gradient. Lithological contrasts in hte model produce more complex morphologies and predict the formation of scarps crowned by an erosionaly resistant caprock. However, resistant caprocks are not an essential requirement for model scarps to retreat. We conclude that the inferred controls and model behavior are both consistent with the present-day morphology of rifted continental margins and with modern conceptual models of landscape evolution.

Treatment of atomic and molecular line blanketing by opacity sampling

NASA Technical Reports Server (NTRS)

Johnson, H. R.; Krupp, B. M.

1976-01-01

A sampling technique for treating the radiative opacity of large numbers of atomic and molecular lines in cool stellar atmospheres is subjected to several tests. In this opacity sampling (OS) technique, the global opacity is sampled at only a selected set of frequencies, and at each of these frequencies the total monochromatic opacity is obtained by summing the contribution of every relevant atomic and molecular line. In accord with previous results, we find that the structure of atmospheric models is accurately fixed by the use of 1000 frequency points, and 100 frequency points are adequate for many purposes. The effects of atomic and molecular lines are separately studied. A test model computed using the OS method agrees very well with a model having identical atmospheric parameters, but computed with the giant line (opacity distribution function) method.

High-throughput Raman chemical imaging for evaluating food safety and quality

NASA Astrophysics Data System (ADS)

Qin, Jianwei; Chao, Kuanglin; Kim, Moon S.

2014-05-01

A line-scan hyperspectral system was developed to enable Raman chemical imaging for large sample areas. A custom-designed 785 nm line-laser based on a scanning mirror serves as an excitation source. A 45° dichroic beamsplitter reflects the laser light to form a 24 cm x 1 mm excitation line normally incident on the sample surface. Raman signals along the laser line are collected by a detection module consisting of a dispersive imaging spectrograph and a CCD camera. A hypercube is accumulated line by line as a motorized table moves the samples transversely through the laser line. The system covers a Raman shift range of -648.7-2889.0 cm-1 and a 23 cm wide area. An example application, for authenticating milk powder, was presented to demonstrate the system performance. In four minutes, the system acquired a 512x110x1024 hypercube (56,320 spectra) from four 47-mm-diameter Petri dishes containing four powder samples. Chemical images were created for detecting two adulterants (melamine and dicyandiamide) that had been mixed into the milk powder.

Statistical Methods in Assembly Quality Management of Multi-Element Products on Automatic Rotor Lines

NASA Astrophysics Data System (ADS)

Pries, V. V.; Proskuriakov, N. E.

2018-04-01

To control the assembly quality of multi-element mass-produced products on automatic rotor lines, control methods with operational feedback are required. However, due to possible failures in the operation of the devices and systems of automatic rotor line, there is always a real probability of getting defective (incomplete) products into the output process stream. Therefore, a continuous sampling control of the products completeness, based on the use of statistical methods, remains an important element in managing the quality of assembly of multi-element mass products on automatic rotor lines. The feature of continuous sampling control of the multi-element products completeness in the assembly process is its breaking sort, which excludes the possibility of returning component parts after sampling control to the process stream and leads to a decrease in the actual productivity of the assembly equipment. Therefore, the use of statistical procedures for continuous sampling control of the multi-element products completeness when assembled on automatic rotor lines requires the use of such sampling plans that ensure a minimum size of control samples. Comparison of the values of the limit of the average output defect level for the continuous sampling plan (CSP) and for the automated continuous sampling plan (ACSP) shows the possibility of providing lower limit values for the average output defects level using the ACSP-1. Also, the average sample size when using the ACSP-1 plan is less than when using the CSP-1 plan. Thus, the application of statistical methods in the assembly quality management of multi-element products on automatic rotor lines, involving the use of proposed plans and methods for continuous selective control, will allow to automating sampling control procedures and the required level of quality of assembled products while minimizing sample size.

Nucleotide composition analysis of tRNA from leukemia patient cell samples and human cell lines.

PubMed Central

Agris, P F

1975-01-01

A technique developed for analysis of less than microgram quantities of tRNA has been applied to the study of human leukemia. Leucocytes from peripheal blood and bone marrow samples of six, untreated leukemia patients and cells of five different established human cell lines were maintained for 18 hours in media containing (32P)-phosphate. Incorporation of radioactive phosphate into the cells from the patient samples was slightly less than that of the cell lines. Likewise, incorporation of (32P)-phosphate into the tRNA of the patient samples (approximately 5 x 106 DPM/mug tRNA) was also less then that incorporated into the tRNA of the cell lines. The major and minor nucleotide compositions of the unfractionated tRNA preparations from each patient sample and each cell line were determined and compared. Similarities and differences in the major and minor nucleotide compositions of the tRNA preparations are discussed with reference to types of leukemia and the importance of patient sample analysis versus analysis of cultured human cells. PMID:1057159

Metabolomics Characterization of U.S. and Japanese F-15 and C-130 Flight Line Crews Exposed to Jet Fuel Volatile Organic Compounds and Aerosols

DTIC Science & Technology

2014-09-30

resulted in the identification of metabolite patterns indicative of flight line exposure when compared to non -flight line control subjects...virtually non -invasive sample collection, minimal sample processing, robust and stable analytical platform, with excellent analytical and biological...identification of metabolite patterns indicative of flight line exposure when compared to non -flight line control subjects. Regardless of fuel (JP-4 or

Characteristics and distributions of atmospheric mercury ...

EPA Pesticide Factsheets

Continuous measurements of speciated atmospheric mercury (Hg), including gaseous elemental mercury (GEM), particulate mercury (PHg), and reactive gaseous mercury (RGM) were conducted in Guizhou Province, southwestern China. Guiyang Power Plant (GPP), Guiyang Wujiang Cement Plant, Guizhou Aluminum Plant (GAP), and Guiyang Forest Park (GFP) in Guiyang were selected as study sites. Automatic Atmospheric Mercury Speciation Analyzers (Tekran 2537A) were used for GEM analysis. PHg and RGM were simultaneously collected by a manual sampling system, including elutriator, coupler/impactor, KCl-coated annular denuder, and a filter holder. Results show that different emission sources dominate different species of Hg. The highest average GEM value was 22.2 ± 28.3 ng·m−3 and the lowest 6.1 ± 3.9 ng·m−3, from samples collected at GPP and GAP, respectively. The maximum average PHg was 1984.9 pg·m−3 and the minimum average 55.9 pg·m−3, also from GPP and GAP, respectively. Similarly, the highest average RGM of 68.8 pg·m−3 was measured at GPP, and the lowest level of 20.5 pg·m−3 was found at GAP. We conclude that coal combustion sources are still playing a key role in GEM; traffic contributes significantly to PHg; and domestic pollution dominates RGM. Mercury (Hg) is a persistent hazardous pollutant with adverse effects on human health and wildlife due mainly to bioaccumulation and biomagnification in aquatic food webs (Lindqvist et al. 1991; Schroeder and Munt

Transported acid aerosols measured in southern Ontario

NASA Astrophysics Data System (ADS)

Keeler, Gerald J.; Spengler, John D.; Koutrakis, Petros; Allen, George A.; Raizenne, Mark; Stern, Bonnie

During the period 29 June 1986-9 August 1986, a field health study assessing the acute health effects of air pollutants on children was conducted at a summer girls' camp on the northern shore of Lake Erie in SW Ontario. Continuous air pollution measurements of SO 2, O 3, NO x, particulate sulfates, light scattering, and meteorological measurements including temperature, dew point, and wind speed and direction were made. Twelve-hour integrated samples of size fractioned particles were also obtained using dichotomous samplers and Harvard impactors equipped with an ammonia denuder for subsequent hydrogen ion determination. Particulate samples were analyzed for trace elements by X-ray fluorescence and Neutron Activation, and for organic and elemental carbon by a thermal/optical technique. The measured aerosol was periodically very acidic with observed 12-h averaged H + concentrations in the range < 10-560 nmoles m -3. The aerosol H + appeared to represent the net strong acidity after H 2SO 4 reaction with NH 3(g). Average daytime concentrations were higher than night-time for aerosol H +, sulfate, fine mass and ozone. Prolonged episodes of atmospheric acidity, sulfate, and ozone were associated with air masses arriving at the measurement site from the west and from the southwest over Lake Erie. Sulfate concentrations measured at the lakeshore camp were more than twice those measured at inland sites during extreme pollution episodes. The concentration gradient observed with onshore flow was potentially due to enhanced deposition near the lakeshore caused by discontinuities in the meteorological fields in this region.

Inorganic acid emission factors of semiconductor manufacturing processes.

PubMed

Chein, HungMin; Chen, Tzu Ming; Aggarwal, Shankar Gopala; Tsai, Chuen-Jinn; Huang, Chun-Chao

2004-02-01

A huge amount of inorganic acids can be produced and emitted with waste gases from integrated circuit manufacturing processes such as cleaning and etching. Emission of inorganic acids from selected semiconductor factories was measured in this study. The sampling of the inorganic acids was based on the porous metal denuders, and samples were then analyzed by ion chromatography. The amount of chemical usage was adopted from the data that were reported to the Environmental Protection Bureau in Hsin-chu County according to the Taiwan Environmental Protection Agency regulation. The emission factor is defined as the emission rate (kg/month) divided by the amount of chemical usage (L/month). Emission factors of three inorganic acids (i.e., hydrofluoric acid [HF], hydrochloric acid [HCl], and sulfuric acid [H2SO4]) were estimated by the same method. The emission factors of HF and HCl were determined to be 0.0075 kg/L (coefficient of variation [CV] = 60.7%, n = 80) and 0.0096 kg/L (CV = 68.2%, n = 91), respectively. Linear regression equations are proposed to fit the data with correlation coefficient square (R2) = 0.82 and 0.9, respectively. The emission factor of H2SO4, which is in the droplet form, was determined to be 0.0016 kg/L (CV = 99.2%, n = 107), and its R2 was 0.84. The emission profiles of gaseous inorganic acids show that HF is the dominant chemical in most of the fabricators.

Study on Emission Spectral Lines of Iron, Fe in Laser-Induced Breakdown Spectroscopy (LIBS) on Soil Samples

NASA Astrophysics Data System (ADS)

Idris, Nasrullah; Lahna, Kurnia; Fadhli; Ramli, Muliadi

2017-05-01

In this work, LIBS technique has been used for detection of heavy metal especially iron, Fe in soil sample. As there are a large number of emission spectral lines due to Fe and other constituents in soil, this study is intended to identify emission spectral lines of Fe and finally to find best fit emission spectral lines for carrying out a qualitative and quantitative analysis. LIBS apparatus used in this work consists of a laser system (Neodymium Yttrium Aluminum Garnet, Nd-YAG: Quanta Ray; LAB SERIES; 1,064 nm; 500 mJ; 8 ns) and an optical multichannel analyzer (OMA) system consisting of a spectrograph (McPherson model 2061; 1,000 mm focal length; f/8.6 Czerny- Turner) and an intensified charge coupled device (ICCD) 1024x256 pixels (Andor I*Star). The soil sample was collected from Banda Aceh city, Aceh, Indonesia. For spectral data acquisition, the soil sample has been prepared by a pressing machine in the form of pellet. The laser beam was focused using a high density lens (f=+150 mm) and irradiated on the surface of the pellet for generating luminous plasma under 1 atmosphere of air surrounding. The plasma emission was collected by an optical fiber and then sent to the optical multichannel analyzer (OMA) system for acquisition of the emission spectra. It was found that there are many Fe emission lines both atomic lines (Fe I) and ionic lines (Fe II) appeared in all detection windows in the wavelength regions, ranging from 200 nm to 1000 nm. The emission lines of Fe with strong intensities occurs together with emission lines due to other atoms such as Mg, Ca, and Si. Thus, the identification of emission lines from Fe is complicated by presence of many other lines due to other major and minor elements in soil. Considering the features of the detected emission lines, several emission spectral lines of Fe I (atomic emission line), especially Fe I 404.58 nm occurring at visible range are potential to be good candidate of analytical lines in relation to detection heavy metal pollution, Fe, in soil sample.

Epidermal Homeostasis and Radiation Responses in a Multiscale Tissue Modeling Framework

NASA Technical Reports Server (NTRS)

Hu, Shaowen; Cucinotta, Francis A.

2013-01-01

The surface of skin is lined with several thin layers of epithelial cells that are maintained throughout life time by a small population of stem cells. High dose radiation exposures could injure and deplete the underlying proliferative cells and induce cutaneous radiation syndrome. In this work we propose a multiscale computational model for skin epidermal dynamics that links phenomena occurring at the subcellular, cellular, and tissue levels of organization, to simulate the experimental data of the radiation response of swine epidermis, which is closely similar to human epidermis. Incorporating experimentally measured histological and cell kinetic parameters, we obtain results of population kinetics and proliferation indexes comparable to observations in unirradiated and acutely irradiated swine experiments. At the sub-cellular level, several recently published Wnt signaling controlled cell-cycle models are applied and the roles of key components and parameters are analyzed. Based on our simulation results, we demonstrate that a moderate increase of proliferation rate for the survival proliferative cells is sufficient to fully repopulate the area denuded by high dose radiation, as long as the integrity of underlying basement membrane is maintained. Our work highlights the importance of considering proliferation kinetics as well as the spatial organization of tissues when conducting in vivo investigations of radiation responses. This integrated model allow us to test the validity of several basic biological rules at the cellular level and sub-cellular mechanisms by qualitatively comparing simulation results with published research, and enhance our understanding of the pathophysiological effects of ionizing radiation on skin.

The effects of partial defeathering on energy metabolism in the laying fowl.

PubMed

Tullett, S G; MacLeod, M G; Jewitt, T R

1980-05-01

1. The effects of a complete removal of feathers from the neck and/or breast on the energy metabolism of laying hens were measured by indirect calorimetry. 2. The daily heat production of fed birds was significantly increased if feathers were removed from the entire neck plus breast region but not if the neck only or breast only were denuded. 3. Removal of feathers from neck plus breast led to a 10% increase in food consumption. 4. The partially-defeathered birds laid more eggs.

Upper aerodigestive tract burn: a case report of firework injury.

PubMed

Kerekhanjanarong, V; Supiyaphun, P; Saengpanich, S

2001-02-01

The case of a 46 year-old German man with upper aerodigestive burn by firework was reported. He presented with the symptoms and signs of upper airway obstruction. Tracheostomy was done and direct laryngoscopy with microscopic examination revealed swelling and denudation of the mucosa of the oral cavity and supraglottic area. Intravenous steroids and antibiotics were administrated for treatment. It is suggested that proper management needs an understanding of the mechanism and effect of the corrosive agent. Careful airway management resulted in a good outcome in this patient.

CPC_ACEENA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, Mei; Pekour, Mikhail

The condensation particle counter (CPC 3772 or 3010, TSI) measures the number concentration of aerosols from 10 nm to 3 microns. On the G1, it was operated using an external pump and maintained at 1 LPM using a critical orifice. CPC_CVI was installed after CVI inlet, and CVI inlet was operated between two modes: under-kinetic mode and CVI mode. CPC_Isok (3772) and CPC3025 were installed after iso-kinetic inlet and CPC_TD was after the thermal denuder (TD). The infomation about the TD can be found from FIMS dataset.

Situ soil sampling probe system with heated transfer line

DOEpatents

Robbat, Jr., Albert

2002-01-01

The present invention is directed both to an improved in situ penetrometer probe and to a heated, flexible transfer line. The line and probe may be implemented together in a penetrometer system in which the transfer line is used to connect the probe to a collector/analyzer at the surface. The probe comprises a heater that controls a temperature of a geologic medium surrounding the probe. At least one carrier gas port and vapor collection port are located on an external side wall of the probe. The carrier gas port provides a carrier gas into the geologic medium, and the collection port captures vapors from the geologic medium for analysis. In the transfer line, a flexible collection line that conveys a collected fluid, i.e., vapor, sample to a collector/analyzer. A flexible carrier gas line conveys a carrier gas to facilitate the collection of the sample. A system heating the collection line is also provided. Preferably the collection line is electrically conductive so that an electrical power source can generate a current through it so that the internal resistance generates heat.

Grain quality traits in a sorghum association mapping panel

USDA-ARS?s Scientific Manuscript database

Grain quality traits were analyzed in a diverse sorghum sample set which consisted of 174 sorghum lines (110 non-tannin lines and 64 tannin lines). These samples were previously grouped into five distinct genetic populations which made it possible to compare grain quality traits across the genetic g...

Grain quality traits in sorghum association mapping panel

USDA-ARS?s Scientific Manuscript database

Grain quality traits were analyzed in a diverse sorghum sample set which consisted of 174 sorghum lines (110 non-tannin lines and 64 tannin lines). These samples were previously grouped into five distinct genetic populations which made it possible to compare grain quality traits across the genetic g...

A parametric generalization of the Hayne estimator for line transect sampling

USGS Publications Warehouse

Burnham, Kenneth P.

1979-01-01

The Hayne model for line transect sampling is generalized by using an elliptical (rather than circular) flushing model for animal detection. By assuming the ration of major and minor axes lengths is constant for all animals, a model results which allows estimation of population density based directly upon sighting distances and sighting angles. The derived estimator of animal density is a generalization of the Hayne estimator for line transect sampling.

State of the art in on-line techniques coupled to flow injection analysis FIA/on-line- a critical review

PubMed Central

Puchades, R.; Maquieira, A.; Atienza, J.; Herrero, M. A.

1990-01-01

Flow injection analysis (FIA) has emerged as an increasingly used laboratory tool in chemical analysis. Employment of the technique for on-line sample treatment and on-line measurement in chemical process control is a growing trend. This article reviews the recent applications of FlA. Most papers refer to on-line sample treatment. Although FIA is very well suited to continuous on-line process monitoring, few examples have been found in this areamost of them have been applied to water treatment or fermentation processes. PMID:18925271

Line intersect sampling: Ell-shaped transects and multiple intersections

Treesearch

Timothy G. Gregoire; Harry T. Valentine

2003-01-01

The probability of selecting a population element under line intersect sampling depends on the width of the particle in the direction perpendicular to the transect, as is well known. The consequence of this when using ell-shaped transects rather than straight-line transects are explicated, and modifications that preserve design-unbiasedness of Kaiser's (1983)...

Line Intercept (LI)

Treesearch

John F. Caratti

2006-01-01

The FIREMON Line Intercept (LI) method is used to assess changes in plant species cover for a macroplot. This method uses multiple line transects to sample within plot variation and quantify statistically valid changes in plant species cover and height over time. This method is suited for most forest and rangeland communities, but is especially useful for sampling...

7 CFR 52.38b - Statistical sampling procedures for on-line inspection by attributes of processed fruits and...

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 2 2011-01-01 2011-01-01 false Statistical sampling procedures for on-line inspection by attributes of processed fruits and vegetables. 52.38b Section 52.38b Agriculture Regulations of... Regulations Governing Inspection and Certification Sampling § 52.38b Statistical sampling procedures for on...

7 CFR 52.38b - Statistical sampling procedures for on-line inspection by attributes of processed fruits and...

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Statistical sampling procedures for on-line inspection by attributes of processed fruits and vegetables. 52.38b Section 52.38b Agriculture Regulations of... Regulations Governing Inspection and Certification Sampling § 52.38b Statistical sampling procedures for on...

Size optimization for complex permeability measurement of magnetic thin films using a short-circuited microstrip line up to 30 GHz

NASA Astrophysics Data System (ADS)

Takeda, Shigeru; Naoe, Masayuki

2018-03-01

High-frequency permeability spectra of magnetic films were measured over a wideband frequency range of 0.1-30 GHz using a shielded and short-circuited microstrip line jig. In this measurement, spurious resonances had to be suppressed up to the highest frequency. To suppress these resonances, characteristic impedance of the microstrip line should approach 50 Ω at the junction between connector and microstrip line. The main factors dominating these resonances were structures of the jig and the sample. The dimensions were optimized in various experiments, and results demonstrated that the frequency could be raised to at least 20 GHz. For the transverse electromagnetic mode to transmit stably along the microstrip line, the preferred sample was rectangular, with the shorter side parallel to the line and the longer side perpendicular to it, and characteristic impedance strongly depended on the signal line width of the jig. However, too small a jig and sample led to a lower S/N ratio.

Wind speed and sediment transport recovery in the lee of a vegetated and denuded nebkha within a nebkha dune field

NASA Astrophysics Data System (ADS)

Gillies, John A.; Nield, Joanna M.; Nickling, William G.

2014-03-01

Field observations of scaled wind speed and sand transport recovery in the lee of a nebka within a field of nebkhas and then subsequently for the nebkha denuded of its vegetation cover were collected. The measurements of wind speed at 0.4 times the element height indicate that for both conditions wind speed recovery in the lee is exponential. The porous vegetation cover influences the rate of this recovery being more gradual for the vegetated form. The return to equilibrium wind speed occurs in both cases at approximately eight element heights. For either case the recovery of shear stress and the return to a constant value occurs much closer to the bluff body form than has been described for porous fences. The recovery of sand transport in the lee appears to be more rapid for the un-vegetated condition, which corresponds to the observed faster rate of wind speed increase. The observations did not show a continual increase in saltation flux with increasing downwind distance due to the increasing shear stress downwind and the increase that may be expected due to the fetch effect. The change in saltation flux with downwind distance was controlled by the sediment supply, which diminished with downwind distance. The interaction of a changing shear stress and the zone of influence created by the wind as it interacts with the roughness dimensions, along with the distribution of sediment available for transport bring increased complexity to modeling sand flux for this type of environment over different temporal scales.

Chitosan nanoparticle carrying small interfering RNA to platelet-derived growth factor B mRNA inhibits proliferation of smooth muscle cells in rabbit injured arteries.

PubMed

Xia, He; Jun, Ji; Wen-Ping, Ling; Yi-Feng, Pan; Xiao-Ling, Chen

2013-10-01

The purpose of this study was to elucidate the transfection of chitosan nanoparticle carrying small interfering RNA against platelet-derived growth factor B (PDGF-B) to inhibit the expression of PDGF-B mRNA and proliferation of smooth muscle cells. A rabbit iliac artery injury model was constructed. A small interfering RNA (siRNA) against PDGF-B mRNA expression vector was constructed and packaged by chitosan nanoparticle to transfect into the vascular smooth muscle cells (vSMCs) of balloon catheter-injured rabbit iliac artery wall, using a therapeutic ultrasound for the gene delivery. The experiment was divided into two groups: experimental group, denudation and nano-PDGF-B siRNA treated, and only single denudation as control. Effects of the siRNA on the expressions of proliferating cell nuclear antigen (PCNA) and PDGF-B mRNA by vSMCs and the proliferation of vSMCs were observed with the methods of routine pathological, immunohistochemical staining, in situ hybridization and morphometry. The nano siRNA against PDGF-B was successfully transfected. The nano siRNA significantly inhibited the expressions of PCNA and PDGF-B mRNA in intimal vSMCs. The local intimal thickness and area were also reduced remarkably. In conclusion, transfection of chitosan nanoparticle carrying siRNA against PDGF-B mRNA could inhibit proliferation of vSMCs in the rabbit iliac artery injury model. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Testing Spatial Correlation of Subduction Interplate Coupling and Forearc Morpho-Tectonics

NASA Technical Reports Server (NTRS)

Goldfinger, Chris; Meigs, Andrew; Meigs, Andrew; Kaye, Grant D.; VanLaningham, Sam

2005-01-01

Subduction zones that are capable of generating great (Mw greater than 8) earthquakes appear to have a common assemblage of forearc morphologic elements. Although details vary, each have (from the trench landward), an accretionary prism, outer arc high, outer forearc basin, an inner forean: basin, and volcanic arc. This pattern is common in spite of great variation in forearc architecture. Because interseismic strain is known to be associated with a locked seismogenic plate interface, we infer that this common forearc morphology is related, in an unknown way, to the process of interseismic Strain accumulation and release in great earthquakes. To date, however, no clear relationship between the subduction process and the common elements of upper plate form has emerged. Whereas certain elements of the system, i.e. the outer arc high, are reasonably well- understood in a structural context, there is little understanding of the structural or topographic evolution of the other key elements like the inner arc and inner forearc basin, particularly with respect to the coupled zone of earthquake generation. This project developed a model of the seismologic, topographic, and uplift/denudation linkages between forearc topography and the subduction system by: 1) comparing geophysical, geodetic, and topographic data from subduction margins that generate large earthquakes; 2) using existing GPS, seismicity, and other data to model the relationship between seismic cycles involving a locked interface and upper-plate topographic development; and 3) using new GPS data and a range-scale topographic, uplift, and denudation analysis of the presently aseismic Cascadia margin to constrain topographic/plate coupling relationships at this poorly understood margin.

A combination of genistein and magnesium enhances the vasodilatory effect via an eNOS pathway and BK(Ca) current amplification.

PubMed

Sun, Lina; Hou, Yunlong; Zhao, Tingting; Zhou, Shanshan; Wang, Xiaoran; Zhang, Liming; Yu, Guichun

2015-04-01

The phytoestrogen genistein (GST) and magnesium have been independently shown to regulate vascular tone; however, their individual vasodilatory effects are limited. The aim of this study was to examine the combined effects of GST plus magnesium on vascular tone in mesenteric arteries. The effects of pretreatment with GST (0-200 μmol/L), MgCl2 (0-4.8 mmol/L) and GST plus MgCl2 on 10 μmol/L phenylephrine (PE) precontracted mesenteric arteries in rats were assessed by measuring isometric force. BK(Ca) currents were detected by the patch clamp method. GST caused concentration- and partial endothelium-dependent relaxation. Magnesium resulted in dual adjustment of vascular tone. Magnesium-free solution eliminated the vasodilatation of GST in both endothelium-intact and denuded rings. GST (50 μmol/L) plus magnesium (4.8 mmol/L) caused stronger relaxation in both endothelium-intact and denuded rings. Pretreatment with the nitric oxide synthase (NOS) inhibitor L-N-nitroarginine methyl ester (L-NAME, 100 μmol/L) significantly inhibited the effects of GST, high magnesium, and the combination of GST and magnesium. BK(Ca) currents were amplified to a greater extent when GST (50 μmol/L) was combined with 4.8 versus 1.2 mmol/L Mg(2+). Our data suggest that GST plus magnesium provides enhanced vasodilatory effects in rat mesenteric arteries compared with that observed when either is used separately, which was related to an eNOS pathway and BK(Ca) current amplification.

Diabetes attenuates urothelial modulation of detrusor contractility and spontaneous activity.

PubMed

Wang, Yi; Tar, Moses T; Fu, Shibo; Melman, Arnold; Davies, Kelvin P

2014-10-01

To investigate the effect of diabetes on urothelial modulation of bladder contractility. Bladder strips (urothelium intact or denuded) were prepared from 8-week-old streptozotocin-induced diabetic (n = 19) and non-diabetic control rats (n = 10). The effect of modulators of MaxiK (iberiotoxin and tetraethylammonium) and Kv7 (XE991 and retigabine) potassium channel activity were investigated for their effects on both carbachol-induced force generation and spontaneous contractile activity. In bladder strips from non-diabetic animals, the presence of the urothelium resulted in marked sensitivity to carbachol-induced force generation by modulators of MaxiK and Kv7 channel activity, whereas in the diabetic animal urothelial sensitivity to these agents was significantly diminished. Urothelial-intact bladder strips from non-diabetic animals were more sensitive to modulators of Kv7 activity in reducing the amplitude of spontaneous phasic contractions than urothelial-denuded bladder strips, whereas in diabetic animals the presence or absence of the urothelium did not alter the sensitivity to modulators of Kv7 activity. Spontaneous activity in the presence of tetraethylammonium was not affected by the urothelium in bladder strips from either diabetic or non-diabetic animals. The presence of the urothelium in bladders from non-diabetic animals modulates the activity of potassium blockers to affect bladder contractility, whereas in the diabetic bladder this effect is attenuated. These findings could help to explain the lack of success of pharmaceutical treatments targeting potassium channels to treat bladder pathology in patients with diseases imparing urothelial function. © 2014 The Japanese Urological Association.

A novel inlet system for online chemical analysis of semi-volatile submicron particulate matter

NASA Astrophysics Data System (ADS)

Eichler, P.; Müller, M.; D'Anna, B.; Wisthaler, A.

2015-03-01

We herein present a novel modular inlet system designed to be coupled to low-pressure gas analyzers for online chemical characterization of semi-volatile submicron particles. The "chemical analysis of aerosol online" (CHARON) inlet consists of a gas-phase denuder for stripping off gas-phase analytes, an aerodynamic lens for particle collimation combined with an inertial sampler for the particle-enriched flow and a thermodesorption unit for particle volatilization prior to chemical analysis. The denuder was measured to remove gas-phase organics with an efficiency > 99.999% and to transmit particles in the 100-750 nm size range with a 75-90% efficiency. The measured average particle enrichment factor in the subsampling flow from the aerodynamic lens was 25.6, which is a factor of 3 lower than the calculated theoretical optimum. We coupled the CHARON inlet to a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) which quantitatively detects most organic analytes and ammonia. The combined CHARON-PTR-ToF-MS setup is thus capable of measuring both the organic and the ammonium fraction in submicron particles in real time. Individual organic compounds can be detected down to levels of 10-20 ng m-3. Two proof-of-principle studies were carried out for demonstrating the analytical power of this new instrumental setup: (i) oxygenated organics and their partitioning between the gas and the particulate phase were observed from the reaction of limonene with ozone and (ii) nicotine was measured in cigarette smoke particles demonstrating that selected organic target compounds can be detected in submicron particles in real time.

The dynamic pattern of PLIN3 in pig oocytes and cumulus cells during in vitro maturation.

PubMed

Xu, Mingzhu; Zeng, Yaqiong; Chi, Daming; Si, Linan; Qu, Xiao; Li, Juan

2018-02-01

Lipid droplets (LDs) are the main energy resource for porcine preimplantation embryonic development. PLIN3 has been implicated in LD formation and regulation. Therefore, this study aimed to detect the dynamic pattern of PLIN3 in pig oocytes and cumulus cells (CC) during in vitro maturation (IVM), and to determine the relationship between PLIN3 and LD content. IVM with cumulus-enclosed oocytes (CEO), cumulus-denuded oocytes (DO) and the CCs denuded from the corresponding oocytes (DCC) was performed in porcine follicular fluid (PFF) or PFF-free optimized medium. DO and the DCC were cultured together under the same conditions as described above, while the DO was named DTO and the DCC was named DTCC in this group. Firstly, our results revealed LDs distributed widely in oocytes and CC, while the PLIN3 protein coated these LDs and spread out ubiquitously in the cytoplasm. Secondly, not only the mRNA level but also at protein level of PLIN3 in immature naked oocytes (IO) was higher than that in matured CEO, DO and DTO. Although PLIN3 was expressed at lower levels in CC from immature oocytes (ICC), the protein level of PLIN3 was comparably higher in the ECC and DCC groups. The triglyceride (TG) content in CEO and DO was significantly less abundant compared with that in IO. Therefore, our results indicated that co-culturing of oocytes and CC might affect PLIN3 expression levels in CC but not in oocytes. Lipid accumulation in pig oocytes during maturation might be affected by PLIN3 cross-talk between oocytes and CC.

Effect of Zoledronate on Oral Wound Healing in Rats

PubMed Central

Yamashita, Junro; Koi, Kiyono; Yang, Dong-Ye; McCauley, Laurie K.

2010-01-01

Purpose Osteonecrosis of the jaw (ONJ) is a growing concern in patients who receive bisphosphonates which target osteoclasts. Since osteoclasts play multifunctional roles in the bone marrow, their suppression likely affects bone homeostasis and alters wound healing of the jaw. The objective was to delineate the impact of osteoclast suppression in the bone marrow and wound healing of the jaw. Experimental Design Zoledronate was administered to senile rats for 14 weeks. A portion of the gingiva was removed to denude the palatal bone. Gene expression in the bone marrow was assessed and histologic sections analyzed to determine the wound healing status. Results Angiogenesis-related genes, CD31 and VEGF-A, were not altered by zoledronate. VEGF-C, which plays a role in lymphangiogenesis, was suppressed. There was a decrease in gene expression of Tcirg1 and MMP-13. Bone denudation caused extensive osteocyte death indicative of bone necrosis. In zoledronate-treated rats, the necrotic bone was retained in the wound while, in controls, osteoclastic resorption of the necrotic bone was prominent. Even though large necrotic bone areas existed in zoledronate-treated rats, overlaying soft tissue healed clinically. Immunohistochemical staining showed rich vascularity in the overlaying soft tissue. Conclusions Zoledronate therapy impacts bone marrow by suppressing genes associated with lymphoangiogenesis and tissue remodeling, such as VEGF-C and MMP-13. Zoledronate was associated with impaired osseous wound healing but had no effect on angiogenic markers in the bone marrow or soft tissue wound healing. Zoledronate selectively blunts healing in bone but does not effect soft tissue healing in the oral cavity. PMID:21149614

Twelve testable hypotheses on the geobiology of weathering.

PubMed

Brantley, S L; Megonigal, J P; Scatena, F N; Balogh-Brunstad, Z; Barnes, R T; Bruns, M A; Van Cappellen, P; Dontsova, K; Hartnett, H E; Hartshorn, A S; Heimsath, A; Herndon, E; Jin, L; Keller, C K; Leake, J R; McDowell, W H; Meinzer, F C; Mozdzer, T J; Petsch, S; Pett-Ridge, J; Pregitzer, K S; Raymond, P A; Riebe, C S; Shumaker, K; Sutton-Grier, A; Walter, R; Yoo, K

2011-03-01

Critical Zone (CZ) research investigates the chemical, physical, and biological processes that modulate the Earth's surface. Here, we advance 12 hypotheses that must be tested to improve our understanding of the CZ: (1) Solar-to-chemical conversion of energy by plants regulates flows of carbon, water, and nutrients through plant-microbe soil networks, thereby controlling the location and extent of biological weathering. (2) Biological stoichiometry drives changes in mineral stoichiometry and distribution through weathering. (3) On landscapes experiencing little erosion, biology drives weathering during initial succession, whereas weathering drives biology over the long term. (4) In eroding landscapes, weathering-front advance at depth is coupled to surface denudation via biotic processes. (5) Biology shapes the topography of the Critical Zone. (6) The impact of climate forcing on denudation rates in natural systems can be predicted from models incorporating biogeochemical reaction rates and geomorphological transport laws. (7) Rising global temperatures will increase carbon losses from the Critical Zone. (8) Rising atmospheric P(CO2) will increase rates and extents of mineral weathering in soils. (9) Riverine solute fluxes will respond to changes in climate primarily due to changes in water fluxes and secondarily through changes in biologically mediated weathering. (10) Land use change will impact Critical Zone processes and exports more than climate change. (11) In many severely altered settings, restoration of hydrological processes is possible in decades or less, whereas restoration of biodiversity and biogeochemical processes requires longer timescales. (12) Biogeochemical properties impart thresholds or tipping points beyond which rapid and irreversible losses of ecosystem health, function, and services can occur. © 2011 Blackwell Publishing Ltd.

Gaseous and aerosol pollutants during fog and clear episodes in South Asian urban atmosphere

NASA Astrophysics Data System (ADS)

Biswas, K. F.; Ghauri, Badar M.; Husain, Liaquat

We report the first measurements of acidic gases and ammonia (NH 3) during fog and clear episodes in Lahore, a highly polluted mega-city of South Asia, along with concentrations of PM 2.5 (particles of <2.5 μm aerodynamic diameter) and ions. An annular denuder system was used to measure acidic gases, NH 3, and PM 2.5 from December 2005 to February 2006 in Lahore, a mega-city in Pakistan. The denuders yielded average concentrations (μg m -3) as follows: ammonia, 50; nitrous acid, 19.6; sulfur dioxide, 19.4; hydrochloric acid, 1.16; nitric acid, 1.00; and oxalic acid, 0.6. The filters yielded average concentrations (μg m -3): PM 2.5, 209; sulfate, 19.2; nitrate, 18.9; chloride, 7.43; oxalate, 0.97; ammonium, 16.1; potassium, 3.49; calcium, 0.89; sodium, 0.76; and magnesium, 0.08. Emissions from local sources, e.g., fossil fuel consumption by motorized transport and power plants, farming, burning of agricultural residues, industrial and construction activities contributed the major proportion of pollutants in Lahore. Concentrations of ionic species, e.g., NO 3-, SO 42-, Na +, NH 4+, Mg 2+, and Ca 2+, and gaseous species, e.g., HCl, HNO 3, SO 2 and (COOH) 2 showed a distinct diurnal variation. Mixing heights and photochemistry played major roles in defining the diurnal pattern. Fog appeared to profoundly enhance the oxidation of sulfur dioxide. High moisture content of fog resulted in uptake of the gases in fog droplets.

Accelerating Anthropogenic Land Surface Change and the Status of Pleistocene Drumlins in New England

PubMed Central

Woodcock, Deborah W.; Rogan, John S.; Blanchard, Samuel D.

2012-01-01

Drumlins are glacially derived landforms that are prominent in the landscape over much of southern New England. We carried out a comprehensive ground-based survey in a three-town study area in eastern Massachusetts with the goals of establishing the extent to drumlins have been altered and assessing the associated environmental consequences and probable driving factors. Results show that many drumlins have been significantly altered through levelling and truncation (creation of steep cut and fill slopes), with projects involving movement of 1−1.5×106 m3 of earth materials not now uncommon. Stormwater and wetlands infractions were documented at all the larger excavation sites and resulted in enforcement actions and fines in many cases; the broader environmental consequences of the loss/alteration of these forested uplands are harder to establish. The excavations are significant in terms of materials cycling: the movement of earth materials, when considered regionally, greatly exceeds natural denudation processes and is also greater than during other periods of high anthropogenic denudation. Our findings suggest that the region’s glacial landscapes are at risk given current development patterns. The accelerating rate of land-surface change is undoubtedly also generalizable to other fast-developing regions of the United States. The landform alterations documented are part of a changing pattern of land use and vegetation cover since the Colonial era and are linked to shortages of land for development, current development and building practices, and lack of explicit rationales for preservation of the region’s geoheritage. PMID:23056410

Quaternary Sedimentary Processes and Budgets in Orphan Basin, Southwestern Labrador Sea

NASA Astrophysics Data System (ADS)

Hiscott, Richard N.; Aksu, Ali E.

1996-03-01

The continental slope in Orphan Basin, northeast of Newfoundland, is underlain by several seaward-thinning debris-flow wedges alternating with acoustically stratified, regionally extensive, mainly hemipelagic sediments. δ 18O stratigraphy and volcanic ash layers in a 11.67-m core indicate that the uppermost debris-flow wedge formed during the last of several sea-level lowstands in isotopic stages 2-4. Similarly, seismic reflection correlation of dated levels at DSDP Site 111 with the Orphan Basin succession suggests that two deeper debris-flow wedges were deposited during oxygen isotopic stages 6 and 8. The oldest of the debris-flow deposits in at least three of the wedges formed well into the corresponding glacial cycle, after ice sheets had reached the edge of the continental shelf. Slower deposition by hemipelagic processes and ice rafting formed the acoustically stratified units, including Heinrich layers. The youngest three debris-flow wedges each have volumes of 1300-1650 km 3. Approximately two-thirds of this material is attributed to glacial erosion of Mesozoic and Tertiary strata beneath the Northeast Newfoundland Shelf. The remainder is believed to have been derived by glacial erosion of older bedrock that now forms the island of Newfoundland. The observed sediment volumes and the inferred basal and upper ages of the debris-flow wedges imply an average glacial denudation rate of about 0.13 mm/yr for this older bedrock, and an average of about 60 m of glacial bedrock erosion since oxygen isotope stage 22. This denudation rate is similar to estimates from the Barents Sea region off Norway.

Landslide susceptibility revealed by LIDAR imagery and historical records, Seattle, Washington

USGS Publications Warehouse

Schulz, W.H.

2007-01-01

Light detection and ranging (LIDAR) data were used to visually map landslides, headscarps, and denuded slopes in Seattle, Washington. Four times more landslides were mapped than by previous efforts that used aerial photographs. The mapped landforms (landslides, headscarps, and denuded slopes) were created by many individual landslides. The spatial distribution of mapped landforms and 1308 historical landslides show that historical landslide activity has been concentrated on the mapped landforms, and that most of the landslide activity that created the landforms was prehistoric. Thus, the spatial densities of historical landslides on the landforms provide approximations of the landforms' relative susceptibilities to future landsliding. Historical landslide characteristics appear to be closely related to landform type so relative susceptibilities were determined for landslides with various characteristics. No strong relations were identified between stratigraphy and landslide occurrence; however, landslide characteristics and slope morphology appear to be related to stratigraphic conditions. Human activity is responsible for causing about 80% of historical Seattle landslides. The distribution of mapped landforms and human-caused landslides suggests the probable characteristics of future human-caused landslides on each of the landforms. The distribution of mapped landforms and historical landslides suggests that erosion of slope-toes by surface water has been a necessary condition for causing Seattle landslides. Human activity has largely arrested this erosion, which implies that landslide activity will decrease with time as hillsides naturally stabilize. However, evaluation of glacial-age analogs of areas of recent slope-toe erosion suggests that landslide activity in Seattle will continue for the foreseeable future. ?? 2006 Elsevier B.V. All rights reserved.

Loss of basal cells precedes bronchiolitis obliterans-like pathological changes in a murine model of chlorine gas inhalation.

PubMed

O'Koren, Emily G; Hogan, Brigid L M; Gunn, Michael Dee

2013-11-01

Bronchiolitis obliterans (BO) is a major cause of chronic airway dysfunction after toxic chemical inhalation. The pathophysiology of BO is not well understood, but epithelial cell injury has been closely associated with the development of fibrotic lesions in human studies and in animal models of both toxin-induced and transplant-induced BO. However, whereas almost all cases and models of BO include epithelial injury, not all instances of epithelial injury result in BO, suggesting that epithelial damage per se is not the critical event leading to the development of BO. Here, we describe a model of chlorine-induced BO in which mice develop tracheal and large airway obliterative lesions within 10 days of exposure to high (350 parts per million [ppm]), but not low (200 ppm), concentrations of chlorine gas. Importantly, these lesions arise only under conditions and in areas in which basal cells, the resident progenitor cells for large airway epithelium, are eliminated by chlorine exposure. In areas of basal cell loss, epithelial regeneration does not occur, resulting in persistent regions of epithelial denudation. Obliterative airway lesions arise specifically from regions of epithelial denudation in a process that includes inflammatory cell infiltration by Day 2 after exposure, fibroblast infiltration and collagen deposition by Day 5, and the ingrowth of blood vessels by Day 7, ultimately leading to lethal airway obstruction by Days 9-12. We conclude that the loss of epithelial progenitor cells constitutes a critical factor leading to the development of obliterative airway lesions after chemical inhalation.

Erosion Rates at the Mars Exploration Rover Landing Sites and Long-Term Climate Change on Mars

NASA Technical Reports Server (NTRS)

Golombek, M. P.; Grant, J. A.; Crumpler, L. S.; Greeley, R.; Arvidson, R. E.; Bell, J. F., III; Weitz, C. M.; Sullivan, R.; Christensen, P. R.; Soderblom, L. A.;

Erosion rates at the Mars Exploration Rover landing sites and long-term climate change on Mars

USGS Publications Warehouse

Golombek, M.P.; Grant, J. A.; Crumpler, L.S.; Greeley, R.; Arvidson, R. E.; Bell, J.F.; Weitz, C.M.; Sullivan, R.J.; Christensen, P.R.; Soderblom, L.A.; Squyres, S. W.

2006-01-01

Erosion rates derived from the Gusev cratered plains and the erosion of weak sulfates by saltating sand at Meridiani Planum are so slow that they argue that the present dry and desiccating environment has persisted since the Early Hesperian. In contrast, sedimentary rocks at Meridiani formed in the presence of groundwater and occasional surface water, and many Columbia Hills rocks at Gusev underwent aqueous alteration during the Late Noachian, approximately coeval with a wide variety of geomorphic indicators that indicate a wetter and likely warmer environment. Two-toned rocks, elevated ventifacts, and perched and undercut rocks indicate localized deflation of the Gusev plains and deposition of an equivalent amount of sediment into craters to form hollows, suggesting average erosion rates of ???0.03 nm/yr. Erosion of Hesperian craters, modification of Late Amazonian craters, and the concentration of hematite concretions in the soils of Meridiani yield slightly higher average erosion rates of 1-10 nm/yr in the Amazonian. These erosion rates are 2-5 orders of magnitude lower than the slowest continental denudation rates on Earth, indicating that liquid water was not an active erosional agent. Erosion rates for Meridiani just before deposition of the sulfate-rich sediments and other eroded Noachian areas are comparable with slow denudation rates on Earth that are dominated by liquid water. Available data suggest the climate change at the landing sites from wet and likely warm to dry and desiccating occurred sometime between the Late Noachian and the beginning of the Late Hesperian (3.7-3.5 Ga). Copyright 2006 by the American Geophysical Union.

Effects of silicate weathering on water chemistry in forested, upland, felsic terrane of the USA

NASA Astrophysics Data System (ADS)

Stauffer, Robert E.; Wittchen, Bruce D.

1991-11-01

We use data from the US EPA National Surface Water Survey (NSWS), the USGS Bench-Mark Station monitoring program, and the National Acid Deposition Program (NADP) to evaluate the role of weathering in supplying base cations to surface waters in forested, upland, felsic terrane of the northeastern, northcentral, and northwestern (Idaho batholith) United States. Multivariate regression reveals differential effects of discharge on individual base cations and silica, but no secular trend in the Ca/Na denudation rate over 24 yr (1965-1988) for the Wild River catchment in the White Mountains. Because the turn-over time for Na in the soil-exchange complex is only ca. 1.5 yr, the long-term behavior of the ratios Ca/Na and Si/Na in waters leaving this catchment indicates that weathering is compensating for base cation export. In every subregion, Ca and Mg concentrations in lakes are statistically linked to nonmarine Na, but the median Ca/Na ratio is greater than the ratio in local plagioclase. We attribute this inequality to nonstoichiometric weathering of calcium in juvenile (formerly glaciated) terrane, not to leaching of exchangeable cations by SO 4, because intraregional and cross-regional statistical analysis reveals no effect of atmospherically derived sulfate ion. The median base cation denudation rates (meq m -2 yr -1) for these American lake regions are: Maine granites (108); western Adirondack felsic gneiss (85); Vermilion batholith (42); Idaho batholith (52). The regional rates are high enough to compensate for present wet deposition of acidifying anions except in some vulnerable lake watersheds in the western Adirondacks.

Comparison of various liquid chromatographic methods involving UV and atmospheric pressure chemical ionization mass spectrometric detection for the efficient trace analysis of phenylurea herbicides in various types of water samples.

PubMed

van der Heeft, E; Dijkman, E; Baumann, R A; Hogendoorn, E A

2000-05-19

The performance of mass spectrometric (MS) detection and UV detection in combination with reversed-phase liquid chromatography without and with the use of coupled column RPLC (LC-LC) has been compared for the trace analysis of phenylurea herbicides in environmental waters. The selected samples of this comparative study originated from an inter-laboratory study. For both detection modes, a 50 mm x 4.6 mm I.D. column and a 100 mm x 4.6 mm I.D. column packed with 3 microm C18 were used as the first (C-1) and second (C-2) column, respectively. Atmospheric pressure chemical ionization mass spectrometry was performed on a magnetic sector instrument. The LC-LC-MS analysis was carried out on-line by means of direct large volume (11.7 ml) injection (LVI). The performance of both on-line (LVI, 4 ml of sample) and off-line LC-LC-UV (244 nm) analysis was investigated. The latter procedure consisted of a solid-phase extraction (SPE) of 250 ml of water sample on a 500 mg C18 cartridge. The comparative study showed that LC-LC-MS is more selective then LC-LC-UV and, in most cases, more sensitive. The LVI-LC-LC-MS approach combines direct quantification and confirmation of most of the analytes down to a level of 0.01 microg/l in water samples in less then 30 min. As regards LC-LC-UV, the off-line method appeared to be a more viable approach in comparison with the on-line procedure. This method allows the screening of phenylurea's in various types of water samples down to a level of at least 0.05 microg/l. On-line analysis with LVI provided marginal sensitivity (limits of detection of about 0.1 microg/l) and selectivity was sometimes less in case of surface water samples. Both the on-line LVI-LC-LC-MS method and the LC-LC-UV method using off-line SPE were validated by analysing a series of real-life reference samples. These samples were part of an inter-laboratory test and contained residues of herbicides ranging from 0.02 to 0.8 microg/l. Beside good correlation between the methods the data agreed very well with the true values of the samples.

Optical monitor for water vapor concentration

DOEpatents

Kebabian, Paul

1998-01-01

A system for measuring and monitoring water vapor concentration in a sample uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to a water vapor absorption line. In a preferred embodiment, the argon line is split by a magnetic field parallel to the direction of light propagation from the lamp into sets of components of downshifted and upshifted frequencies of approximately 1575 Gauss. The downshifted components are centered on a water vapor absorption line and are thus readily absorbed by water vapor in the sample; the upshifted components are moved away from that absorption line and are minimally absorbed. A polarization modulator alternately selects the upshifted components or downshifted components and passes the selected components to the sample. After transmission through the sample, the transmitted intensity of a component of the argon line varies as a result of absorption by the water vapor. The system then determines the concentration of water vapor in the sample based on differences in the transmitted intensity between the two sets of components. In alternative embodiments alternate selection of sets of components is achieved by selectively reversing the polarity of the magnetic field or by selectively supplying the magnetic field to the emitting plasma.

Optical monitor for water vapor concentration

DOEpatents

Kebabian, P.

1998-06-02

A system for measuring and monitoring water vapor concentration in a sample uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to a water vapor absorption line. In a preferred embodiment, the argon line is split by a magnetic field parallel to the direction of light propagation from the lamp into sets of components of downshifted and upshifted frequencies of approximately 1575 Gauss. The downshifted components are centered on a water vapor absorption line and are thus readily absorbed by water vapor in the sample; the upshifted components are moved away from that absorption line and are minimally absorbed. A polarization modulator alternately selects the upshifted components or downshifted components and passes the selected components to the sample. After transmission through the sample, the transmitted intensity of a component of the argon line varies as a result of absorption by the water vapor. The system then determines the concentration of water vapor in the sample based on differences in the transmitted intensity between the two sets of components. In alternative embodiments alternate selection of sets of components is achieved by selectively reversing the polarity of the magnetic field or by selectively supplying the magnetic field to the emitting plasma. 5 figs.

First Year Sedimentological Characteristics and Morphological Evolution of an Artificial Berm at Fort Myers Beach, Florida

DTIC Science & Technology

2011-06-17

collected in the berm area. In the control areas, surface sediment samples were taken at approximately the toe of the dune (where present...In the berm area, surface sediment samples were taken at approximately the toe of the dune (where 29   present), backbeach, high tide line, mean...samples were taken at approximately the toe of the dune (where present), backbeach, high tide line, mean sea level, low tide line, 2 ft water depth

VizieR Online Data Catalog: Emission lines for SDSS Coronal-Line Forest AGNs (Rose+, 2015)

NASA Astrophysics Data System (ADS)

Rose, M.; Elvis, M.; Tadhunter, C. N.

2017-11-01

In this paper, we make use of SDSS spectra. The basic properties of the CLiF AGN sample studied in this paper are given in Table 1. Note that the outputs of the SDSS pipeline are used only for the sample selection. Detailed measurements of emission line parameters such as the flux and velocity widths are measured using our own methods (Section 4). The redshifts were determined using single Gaussian fits to the [O III] λ5007 emission line. This line was chosen because it is the most prominent emission line in the optical spectra of these and most other AGN. (5 data files).

Imaging Extended Emission-Line Regions of Obscured AGN with the Subaru Hyper Suprime-Cam Survey

NASA Astrophysics Data System (ADS)

Sun, Ai-Lei; Greene, Jenny E.; Zakamska, Nadia L.; Goulding, Andy; Strauss, Michael A.; Huang, Song; Johnson, Sean; Kawaguchi, Toshihiro; Matsuoka, Yoshiki; Marsteller, Alisabeth A.; Nagao, Tohru; Toba, Yoshiki

2018-05-01

Narrow-line regions excited by active galactic nuclei (AGN) are important for studying AGN photoionization and feedback. Their strong [O III] lines can be detected with broadband images, allowing morphological studies of these systems with large-area imaging surveys. We develop a new broad-band imaging technique to reconstruct the images of the [O III] line using the Subaru Hyper Suprime-Cam (HSC) Survey aided with spectra from the Sloan Digital Sky Survey (SDSS). The technique involves a careful subtraction of the galactic continuum to isolate emission from the [O III]λ5007 and [O III]λ4959 lines. Compared to traditional targeted observations, this technique is more efficient at covering larger samples without dedicated observational resources. We apply this technique to an SDSS spectroscopically selected sample of 300 obscured AGN at redshifts 0.1 - 0.7, uncovering extended emission-line region candidates with sizes up to tens of kpc. With the largest sample of uniformly derived narrow-line region sizes, we revisit the narrow-line region size - luminosity relation. The area and radii of the [O III] emission-line regions are strongly correlated with the AGN luminosity inferred from the mid-infrared (15 μm rest-frame) with a power-law slope of 0.62^{+0.05}_{-0.06}± 0.10 (statistical and systematic errors), consistent with previous spectroscopic findings. We discuss the implications for the physics of AGN emission-line regions and future applications of this technique, which should be useful for current and next-generation imaging surveys to study AGN photoionization and feedback with large statistical samples.

Development and application of a sampling method for the determination of reactive halogen species in volcanic gas emissions.

PubMed

Rüdiger, Julian; Bobrowski, Nicole; Liotta, Marcello; Hoffmann, Thorsten

2017-10-01

Volcanoes release large amounts of reactive trace gases including sulfur and halogen-containing species into the atmosphere. The knowledge of halogen chemistry in volcanic plumes can deliver information about subsurface processes and is relevant for the understanding of the impact of volcanoes on atmospheric chemistry. In this study, a gas diffusion denuder sampling method using 1,3,5-trimethoxybenzene (1,3,5-TMB)-coated glass tubes for the in situ derivatization of reactive halogen species (RHS) was characterized by a series of laboratory experiments. The coating proved to be applicable to collect selectively gaseous bromine species with oxidation states (OS) of +1 or 0 (such as Br 2 , BrCl, HOBr, BrO, and BrONO 2 ) while being unreactive to HBr (OS -1). The reaction of 1,3,5-TMB with reactive bromine species forms 1-bromo-2,4,6-TMB-other halogens give corresponding derivatives. Solvent elution of the derivatives followed by analysis with GC-MS results in absolute detection limits of a few nanograms for Br 2 , Cl 2 , and I 2 . In 2015, the technique was applied on volcanic gas plumes at Mt. Etna (Italy) measuring reactive bromine mixing ratios between 0.8 and 7.0 ppbv. Total bromine mixing ratios between 4.7 and 27.5 ppbv were derived from alkaline trap samples, simultaneously taken by a Raschig tube and analyzed with IC and ICP-MS. This leads to the first results of the reactive bromine contribution to total bromine in volcanic emissions, spanning over a range between 12% (±1) and 36% (±2). Our finding is in an agreement with previous model studies, which imply values <44% for plume ages <1 min, which is consistent with the assumed plume age at the sampling sites. Graphical abstract Illustration of the measurement procedure for the determination of reactive halogen species in volcanic plumes.

Development and application of a sampling method for the determination of reactive halogen species in volcanic gas emissions

NASA Astrophysics Data System (ADS)

Rüdiger, Julian; Bobrowski, Nicole; Liotta, Marcello; Hoffmann, Thorsten

2017-04-01

Volcanoes are a potential large source of several reactive atmospheric trace gases including sulfur and halogen containing species. Besides the importance for atmospheric chemistry, the detailed knowledge of halogen chemistry in volcanic plumes can help to get insights into subsurface processes. In this study a gas diffusion denuder sampling method, using a 1,3,5-trimethoxybenzene (1,3,5-TMB) coating for the derivatization of reactive halogen species (RHS), was characterized by dilution chamber experiments. The coating proved to be suitable to collect selectively gaseous bromine species with oxidation states (OS) of +1 or 0 (such as Br2, BrCl, BrO(H) and BrONO2), while being ignorant to HBr (OS -1). The reaction of 1,3,5-TMB with reactive bromine species gives 1-bromo-2,4,6-trimethoxybenzene (1-bromo-2,4,6-TMB) - other halogens give corresponding products. Solvent elution of the derivatized analytes and subsequent analysis with gas chromatography mass spectrometry gives detection limits of 10 ng or less for Br2, Cl2, and I2. In 2015 the method was applied on volcanic gas plumes at Mt. Etna (Italy) giving reactive bromine mixing ratios from 0.8 ppbv to 7.0 ppbv. Total bromine mixing ratios of 4.7 ppbv to 27.5 ppbv were obtained by simultaneous alkaline trap sampling (by a Raschig-tube) followed by analysis with ion chromatography and inductively coupled plasma mass spectrometry. This leads to the first results of in-situ measured reactive bromine to total bromine ratios, spanning a range between 12±1 % and 36±2 %. Our finding is in an agreement with previous model studies, which imply values < 44 % for plume ages < 1 minute, which is consistent with the assumed plume age at the sampling sites.

Edge Effects in Line Intersect Sampling With

Treesearch

David L. R. Affleck; Timothy G. Gregoire; Harry T. Valentine

2005-01-01

Transects consisting of multiple, connected segments with a prescribed configuration are commonly used in ecological applications of line intersect sampling. The transect configuration has implications for the probability with which population elements are selected and for how the selection probabilities can be modified by the boundary of the tract being sampled. As...

Design unbiased estimation in line intersect sampling using segmented transects

Treesearch

David L.R. Affleck; Timothy G. Gregoire; Harry T. Valentine; Harry T. Valentine

2005-01-01

In many applications of line intersect sampling. transects consist of multiple, connected segments in a prescribed configuration. The relationship between the transect configuration and the selection probability of a population element is illustrated and a consistent sampling protocol, applicable to populations composed of arbitrarily shaped elements, is proposed. It...

Evaluating cell lines as tumour models by comparison of genomic profiles

PubMed Central

Domcke, Silvia; Sinha, Rileen; Levine, Douglas A.; Sander, Chris; Schultz, Nikolaus

2013-01-01

Cancer cell lines are frequently used as in vitro tumour models. Recent molecular profiles of hundreds of cell lines from The Cancer Cell Line Encyclopedia and thousands of tumour samples from the Cancer Genome Atlas now allow a systematic genomic comparison of cell lines and tumours. Here we analyse a panel of 47 ovarian cancer cell lines and identify those that have the highest genetic similarity to ovarian tumours. Our comparison of copy-number changes, mutations and mRNA expression profiles reveals pronounced differences in molecular profiles between commonly used ovarian cancer cell lines and high-grade serous ovarian cancer tumour samples. We identify several rarely used cell lines that more closely resemble cognate tumour profiles than commonly used cell lines, and we propose these lines as the most suitable models of ovarian cancer. Our results indicate that the gap between cell lines and tumours can be bridged by genomically informed choices of cell line models for all tumour types. PMID:23839242

Long-term landscape evolution of the South Atlantic passive continental margin along the Kaoko- and Damara Belts, NW-Namibia

NASA Astrophysics Data System (ADS)

Menges, Daniel; Glasmacher, Ulrich Anton; Hackspacher, Peter; Schneider, Gabriele; Salomon, Eric

2015-04-01

The Kaoko Belt in northwestern Namibia originates in the collision of the Rio de la Plata and Kongo Craton during the Pan-African Orogeny in the Neoproterozoic (1) and represents the northern arm of the Damara Orogen. NW-Namibias continental crust mainly consists of the NE-SW striking intracontinental branch of the Pan-African Damara mobile belt, which separates the Congo from the Kalahari craton. The Damara Orogen is divided into several tectonostratigraphic zones that are bounded by steeply dipping, ductile shear zones. These regional lineaments can be traced at least 150 km offshore (2). The lithostratigraphic units consist of Proterozoic and Cambrian metamorphosed rocks (534 (7) Ma - 481 (25) Ma (3) as well as Mesozoic sedimentary and igneous rocks. From Permo-Carboniferous to Mid Jurassic northern Namibia was affected by deep erosion of the Damara Orogen, Permo-Triassic collisional processes along the southern margin of Gondwana and eastern margin of Africa (4), and the deposition of the Nama Group sediments and the Karoo megasequence (5). Between the Otjihorongo and the Omaruru Lineament-Waterberg Thrust early Mesozoic tectonic activity is recorded by coarse clastic sediments deposited within NE trending half-graben structures. The Early Jurassic Karoo flood basalt lavas erupted rapidly at 183±1 Ma (6). The Early Cretaceous Paraná-Etendeka flood basalts (132±1 Ma) and mafic dike swarms mark the rift stage of the opening of the South Atlantic (7). Early Cretaceous alkaline intrusions (137-124 Ma) occur preferentially along Mesozoic half-graben structures and are called the Damaraland Igneous Province (8). Late Cretaceous alkaline intrusions and kimberlite pipes occur in northern Namibia. Post Early Paleocene siliciclastic sedimentation in Namibia was largely restricted to a 150 km wide zone (9) and is represented by the Tsondab Sandstone Formation (~ 300 m thickness). The oldest part has an age of early Paleocene and the upper part span from middle Miocene (~13 Ma) to Pliocene (~2 Ma) (10). Cenozoic alkaline intrusions and kimberlite pipes are also known from the region. The so-called "Great Escarpment" that reach elevation of up to 2350 m characterizes strongly the morphology of the passive continental margin in Namibia (11,12). In contrast to Brazil, the escarpment is more than 150 km inland of Namibia. Interesting enough the Brandenberg intrusive complex of ~130 Ma age clearly indicates the post-intrusion denudation of more than 4,000m (13). The Great Escarpment can be traced from central Angola to the eastern edge of South Africa. A considerable variation along its distribution reflects variations in tectonic history, in lithologies, and in the drainage system. In Namibia, the retreating model has dominated the genetic discussion (14,15,16). However, surface process modeling has suggested other possibilities11. In addition, apatite fission-track research, terrigenious cosmogenic nuclides (TCN) have been used on specific landscape elements to determine denudation rates. In the central Namib Desert, denudation rates calculated from 10Be and 26Al are in the range of ±5 m Ma-1 and might be representative for the last 103 - 106 a (17). The persistence of arid climatic conditions throughout the Cenozoic might even lead to such low denudation rates for the past 10-12 Ma. A low retreat rate of ~10 m Ma-1 representative for the last 1 Ma was determined for the Great Escarpment in central and southern Namibia. Considering all currently, available thermochronological data for the Namibian margin (18,19,20), the validity of the scarp retreat model is highly problematic. Apatite fission-track ages revealed so far range between 390.9±17.9 Ma and 80.8±6.0 Ma. The large spread in ages is partly related to significant changes of ages at the NW-SE trending Purros Lineament and at the Sesfontein thrust. In general, the AFT-ages are older northeast of the Purros Lineament. Furthermore, all basalt samples of Etendeka age display the same AFT-age range within error, between 103.5±4.9 and 108.0±5.6 Ma. The oldest ages are revealed from metamorphic rocks of the Damara Group as well as sandstones and glacial deposits of the Permo-Carboniferous Karoo series. References 1. Goscombe, B. D., Gray, D. R., 2008. Structure and strain variation at mid-crustal levels in a transpressional orogen: A review of Kaoko Belt structure and the character of west Gondwana amalgamation and dispersal. Gondwana Res. 13, 45-85. 2. Clemson, J., Cartwright, J., Booth, J., 1997. Structural segmentation and the influence of basement structure on the Namibian passive margin. J. Geol. Soc. London 154, 477-482. 3. Miller, R.M., 1983. Evolution of the Damara Orogen, Vol. 11, Geol. Soc., South Africa Spec. Pub.. 4. Coward, M.P., Daly, M.C., 1984. Crustal lineaments and shear zones in Africa: Their relationships to plate movements, Precambrian Research 24: 27-45. 5. Stollhofen, H., 1999. Karoo Synrift-Sedimentation und ihre tektonische Kontrolle am entstehenden Kontinentalrand Namibias, Z.dt.geol.Ges. 149: 519-632. 6. Duncan, R., Hooper, P., Rehacek, J., March, J., Duncan, A., 1997. The timing and duration of the Karoo igneous event, southern Gondwana, J. Geophy. Res. 102: 18127-18138. 7. Renne, P.R., Glen, J.M., Milner, S.C., Duncan, A.R., 1996. Age of Etendeka flood volcanism and associated intrusions in southwestern Africa, Geology 24 (7): 659- 662. 8. Watkins, R.T., McDougall, I., le Roex, A. P., 1994. K-Ar ages of the Brandberg and Okenenya igneous complexes, north-western Namibia, Geol. Rund. 83: 348-356. 9. Ward, J.D., 1988. Geology of the Tsondab Sandstone Formation, Journal of Sedimentary Geology 55: 143-162. 10. Senut, B., Pickford, M., 1995. Fossil eggs and Cenozoic continental biostratigraphy of Namibia, Pal. Afr.,32: 33-37. 11. Gilchrist, A.R., Kooi, H., Beaumont, C.,1994. Post Gondwana geomorphic evolution of southwestern Africa: Implications for the controls on landscape development from observations and numerical experiments, J. Geophy. Res. 99: 12211-12228. 12. Brown, R. W., Gallagher, K. and Gleadow, A. J. W., 2000. Morphotectonic evolution of the South Atlantic margins of Africa and South America, in M. A. Summerfield (ed.), Geomorphology and Global Tectonics, JohnWiley and Sons Ltd., Chichester, pp. 255-281. 13. Raab, M. J., Brown, R. W., Gallagher, K., Weber, K., Gleadow, A. J. W., 2005. Denudational and thermal history of the Early Cretaceous Brandberg and Okenyenya igneous complexes on Namibia's Atlantic passive margin Tectonics 24: 1-15. 14. Guillocheau, F., Rouby, D., Robin, C. Helm, C., Rolland, N., Le Carlier de Veslud, C., Braun, J., 2012. Quantification and causes of the terrigeneous sediment budget at the scale of a continent margin: a new method applied to the Namibia-South Africa Margin. BasinRes. 24, 3-30. 15. Dauteuil, O., Rouby, D., Braun, J., Guillocheau, F., Deschamps, F., 2013. Post-breakup evolution of the margin of Namibia: constraints from numerical approach. Tectonophysics 604, 122-138. 16. Rouby, D., Braun, J., Dauteuil, O., Deschamps, F., Robin, C., 2013. Long-term stratigraphic evolution of Atlantic-type passive margins: a numerical approach of interactions between surface processes, flexural isostasy and 3D thermal subsidence. Tectonophysics 604, 83-103. 17. Cockburn, H. A. P., Brown, R. W., Summerfield, M. A. and Seidl, M. A., 2000. Quantifying passive margin denudation and landscape development using a combined fission-track thermochronology and cosmogenic isotope analysis approach, EPSL 179: 429-435. 18. Brown, R. W., 1992. A fission track thermochronology study of the tectonic and geomorphic development of the sub-aerial continental margins of southern Africa., PhD thesis, La Trobe University, Bundoora, Australia. 19. Gallagher, K. and Brown, R. W., 1999. Denudation and uplift at passive margins: the record on the Atlantic Margin of southern Africa, Philosophical Transactions Royal Society London A 357: 835-859. 20. Raab, M. J., Brown, R. W., Gallagher, K., Carter, A., Weber, K., 2002. Late Cretaceous reactivation of major crustal shear zones in northern Namibia: constraints from apatite fission track analysis. Tectonophysics 349: 75-92.

Purity, adulteration and price of drugs bought on-line versus off-line in the Netherlands.

PubMed

van der Gouwe, Daan; Brunt, Tibor M; van Laar, Margriet; van der Pol, Peggy

2017-04-01

On-line drug markets flourish and consumers have high expectations of on-line quality and drug value. The aim of this study was to (i) describe on-line drug purchases and (ii) compare on-line with off-line purchased drugs regarding purity, adulteration and price. Comparison of laboratory analyses of 32 663 drug consumer samples (stimulants and hallucinogens) purchased between January 2013 and January 2016, 928 of which were bought on-line. The Netherlands. Primary outcome measures were (i) the percentage of samples purchased on-line and (ii) the chemical purity of powders (or dosage per tablet); adulteration; and the price per gram, blotter or tablet of drugs bought on-line compared with drugs bought off-line. The proportion of drug samples purchased on-line increased from 1.4% in 2013 to 4.1% in 2015. The frequency varied widely, from a maximum of 6% for controlled, traditional substances [ecstasy tablets, 3,4-methylenedioxy-methamphetamine (MDMA) powder, amphetamine powder, cocaine powder, 4-bromo-2,5-dimethoxyphenethylamine (2C-B) and lysergic acid diethylamide (LSD)] to more than a third for new psychoactive substances (NPS) [4-fluoroamphetamine (4-FA), 5/6-(2-aminopropyl)benzofuran (5/6-APB) and methoxetamine (MXE)]. There were no large differences in drug purity, yet small but statistically significant differences were found for 4-FA (on-line 59% versus off-line 52% purity for 4-FA on average, P = 0.001), MDMA powders (45 versus 61% purity for MDMA, P = 0.02), 2C-B tablets (21 versus 10 mg 2C-B/tablet dosage, P = 0.49) and ecstasy tablets (131 versus 121 mg MDMA/tablet dosage, P = 0.05). The proportion of adulterated samples purchased on-line and off-line did not differ, except for 4-FA powder, being less adulterated on-line (χ 2  = 8.3; P < 0.02). Drug prices were mainly higher on-line, ranging for various drugs from 10 to 23% higher than that of drugs purchased off-line (six of 10 substances: P < 0.05). Dutch drug users increasingly purchase drugs on-line: new psychoactive substances in particular. Purity and adulteration do not vary considerably between drugs purchased on-line and off-line for most substances, while on-line prices are mostly higher than off-line prices. © 2016 Society for the Study of Addiction.

Long-Term Behavior of Simulated Partial Lead Service Line Replacements

PubMed Central

St. Clair, Justin; Cartier, Clement; Triantafyllidou, Simoni; Clark, Brandi; Edwards, Marc

2016-01-01

Abstract In this 48-month pilot study, long-term impacts of copper:lead galvanic connections on lead release to water were assessed without confounding differences in pipe exposure prehistory or disturbances arising from cutting lead pipe. Lead release was tracked from three lead service line configurations, including (1) 100% lead, (2) traditional partial replacement with 50% copper upstream of 50% lead, and (3) 50% lead upstream of 50% copper as a function of flow rate, connection types, and sampling methodologies. Elevated lead from galvanic corrosion worsened with time, with 140% more lead release from configurations representing traditional partial replacement configurations at 14 months compared to earlier data in the first 8 months. Even when sampled consistently at moderate flow rate (8 LPM) and collecting all water passing through service lines, conditions representing traditional partial service line configurations were significantly worse (≈40%) when compared to 100% lead pipe. If sampled at a high flow rate (32 LPM) and collecting 2 L samples from service lines, 100% of samples collected from traditional partial replacement configurations exceeded thresholds posing an acute health risk versus a 0% risk for samples from 100% lead pipe. Temporary removal of lead accumulations near Pb:Cu junctions and lead deposits from other downstream plastic pipes reduced risk of partial replacements relative to that observed for 100% lead. When typical brass compression couplings were used to connect prepassivated lead pipes, lead release spiked up to 10 times higher, confirming prior concerns raised at bench and field scale regarding adverse impacts of crevices and service line disturbances on lead release. To quantify semirandom particulate lead release from service lines in future research, whole-house filters have many advantages compared to other approaches. PMID:26989344

Metrological characterization methods for confocal chromatic line sensors and optical topography sensors

NASA Astrophysics Data System (ADS)

Seppä, Jeremias; Niemelä, Karri; Lassila, Antti

2018-05-01

The increasing use of chromatic confocal technology for, e.g. fast, in-line optical topography, and measuring thickness, roughness and profiles implies a need for the characterization of various aspects of the sensors. Single-point, line and matrix versions of chromatic confocal technology, encoding depth information into wavelength, have been developed. Of these, line sensors are particularly suitable for in-line process measurement. Metrological characterization and development of practical methods for calibration and checking is needed for new optical methods and devices. Compared to, e.g. tactile methods, optical topography measurement techniques have limitations related to light wavelength and coherence, optical properties of the sample including reflectivity, specularity, roughness and colour, and definition of optical versus mechanical surfaces. In this work, metrological characterization methods for optical line sensors were developed for scale magnification and linearity, sensitivity to sample properties, and dynamic characteristics. An accurate depth scale calibration method using a single prototype groove depth sample was developed for a line sensor and validated with laser-interferometric sample tracking, attaining (sub)micrometre level or better than 0.1% scale accuracy. Furthermore, the effect of different surfaces and materials on the measurement and depth scale was studied, in particular slope angle, specularity and colour. In addition, dynamic performance, noise, lateral scale and resolution were measured using the developed methods. In the case of the LCI1200 sensor used in this study, which has a 11.3 mm  ×  2.8 mm measurement range, the instrument depth scale was found to depend only minimally on sample colour, whereas measuring steeply sloped specular surfaces in the peripheral measurement area, in the worst case, caused a somewhat larger relative sample-dependent change (1%) in scale.

Preparation and applicability of fresh fruit samples for the identification of radiation treatment by EPR

NASA Astrophysics Data System (ADS)

Yordanov, Nicola D.; Aleksieva, Katerina

2009-03-01

The results of electron paramagnetic resonance (EPR) study on fresh fruits (whole pulp of pears, apples, peaches, apricots, avocado, kiwi and mango) before and after gamma-irradiation are reported using two drying procedures before EPR investigation. In order to remove water from non-irradiated and irradiated samples of the first batch, the pulp of fresh fruits is pressed, and the solid residue is washed with alcohol and dried at room temperature. The fruits of the second batch are pressed and dried in a standard laboratory oven at 40 °C. The results obtained with both drying procedures are compared. All samples under study show a singlet EPR line with g=2.0048±0.0005 before irradiation. Irradiation gives rise to typical "cellulose-like" EPR spectrum featuring one intensive line with g=2.0048±0.0005 and two very weak satellite lines situated 3 mT at left and right of the central line. Only mango samples show a singlet line after irradiation. The fading kinetics of radiation-induced EPR signal is studied for a period of 50 days after irradiation. When the irradiated fruit samples are stored in their natural state and dried just before each EPR measurement, the satellite lines are measurable for less than 17 days of storage. Irradiated fruit samples, when stored dried, lose for 50 days ca. 40% of their radiation-induced radicals if treated with alcohol or ca. 70% if dried in an oven. The reported results unambiguously show that the presence of the satellite lines in the EPR spectra could be used for identification of radiation processing of fresh fruits, thus extending the validity of European Protocol EN 1787 (2000). Foodstuffs—Detection of Irradiated Food Containing Cellulose by EPR Spectroscopy. European Committee for Standardisation. Brussels for dry herbs.

Weathering and landscape evolution

NASA Astrophysics Data System (ADS)

Turkington, Alice V.; Phillips, Jonathan D.; Campbell, Sean W.

2005-04-01

In recognition of the fundamental control exerted by weathering on landscape evolution and topographic development, the 35th Binghamton Geomorphology Symposium was convened under the theme of Weathering and Landscape Evolution. The papers and posters presented at the conference imparted the state-of-the-art in weathering geomorphology, tackled the issue of scale linkage in geomorphic studies and offered a vehicle for interdisciplinary communication on research into weathering and landscape evolution. The papers included in this special issue are encapsulated here under the general themes of weathering mantles, weathering and relative dating, weathering and denudation, weathering processes and controls and the 'big picture'.

A 21st century perspective on postfire seeding

USGS Publications Warehouse

Keeley, J.E.; Allen, Craig D.; Betancourt, J.; Chong, G.W.; Fotheringham, C.J.; Safford, H.D.

2006-01-01

Wildfires elicit a perceived need for emergency action to stabilize denuded landscapes. Aerial seeding of rapidly growing nonnative grasses is used routinely in an attempt to control postfire erosion, despite limited scientific basis for its effectiveness and with little consideration for its unintended ecological impacts. As fire size and magnitude have increased in recent decades, so has the prevalence and cost of postfire seeding and the potential footprint of its unintended impacts. We see a growing consensus in the research community on two important points: this management practice often is not cost-effective and it appears to create more problems than it solves.

Ascaridia galli induced ulcerative proventriculitis in a poultry bird.

PubMed

Brar, Rajinder Singh; Kumar, Rahul; Leishangthem, Geeta Devi; Banga, Harmanjit Singh; Singh, Nittin Dev; Singh, Harkirat

2016-06-01

Various possible causes of proventriculitis include virus, bacteria, fungus, protozoans, nematodes, biogenic amines and excessive copper sulphate. In the present case, parasites were found in the lumen of the proventriculus, gizzard and duodenum of a poultry bird. Characteristic features of the parasite were studied and confirmed as Ascaridia galli. An ulcerative proventriculitis evident as denuded superficial epithelium, sub-epithelial hemorrhages, infiltration of the inflammatory cells and fibrosis were seen at histopathology. Proventriculitis caused by A. galli has not been reported till date. Here, we report a case of ulcerative proventriculitis in a poultry bird caused by nematode, A. galli.

A practical modification of horizontal line sampling for snag and cavity tree inventory

Treesearch

M. J. Ducey; G. J. Jordan; J. H. Gove; H. T. Valentine

2002-01-01

Snags and cavity trees are important structural features in forests, but they are often sparsely distributed, making efficient inventories problematic. We present a straightforward modification of horizontal line sampling designed to facilitate inventory of these features while remaining compatible with commonly employed sampling methods for the living overstory. The...

Controls and variability of solute and sedimentary fluxes in Antarctic and sub-Antarctic Environments

NASA Astrophysics Data System (ADS)

Zwolinski, Zbigniew

2015-04-01

The currently prepared SEDIBUD Book on "Source-to-Sink Fluxes in Undisturbed Cold Environments" (edited by Achim A. Beylich, John C. Dixon and Zbigniew Zwolinski and published by Cambridge University Press) is summarizing and synthesizing the achievements of the International Association of Geomorphologists` (I.A.G./A.I.G.) Working Group SEDIBUD (Sediment Budgets in Cold Environments), which has been active since 2005 (http://www.geomorph.org/wg/wgsb.html). The book comprises five parts. One of them is part about sub-Antarctic and Antarctic Environments. This part "Sub-Antarctic and Antarctic Environments" describes two different environments, namely oceanic and continental ones. Each part contains results of research on environmental drivers and rates of contemporary solute and sedimentary fluxes in selected sites. Apart from describing the environmental conditions of the whole continent of Antarctica and sub-Antarctic islands (Zb.Zwolinski, M.Kejna, A.N.Lastochkin, A.Zhirov, S.Boltramovich) this part of the book characterizes terrestrial polar oases free from multi-year ice and snow covers (Zb.Zwolinski). The detailed results of geoecological and sedimentological research come from different parts of Antarctica. Antarctic continental shelf (E.Isla) is an example of sub-Antarctic oceanic environment. South Shetlands, especially King George Island (Zb.Zwolinski, M.Kejna, G.Rachlewicz, I.Sobota, J.Szpikowski), is an example of sub-Antarctic terrestrial environment. Antarctic Peninsula (G.Vieira, M.Francelino, J.C.Fernandes) and surroundings of McMurdo Dry Valleys (W.B.Lyons, K.A.Welch, J.Levy, A.Fountain, D.McKnight) are examples of Antarctic continental environments. The key goals of the Antarctic and sub-Antarctic book chapters are following: (i) identify the main environmental drivers and rates of contemporary solute and sedimentary fluxes, and (ii) model possible effects of projected climate change on solute and sedimentary fluxes in cold climate environments. Solute and sediment transport in the streams of analyzed environments are constrained by the relatively short water runoff season that typically lasts from a few weeks to maximum of four months during the austral summer, for Antarctic and sub-Antarctic regions respectively. Because of high intensity of mechanical and chemical weathering processes solute and sediment transport are rather high within Antarctic environments. Weathering rates on slopes and magnitude of fluvial transport in relatively short streams control the intensity of denudational processes. Both mechanical and chemical denudation varies highly through sub-Antarctic and Antarctic environments. To generate accurate predictions of fluvial and denudational processes we must fully understand the actual geoecological processes, which in some places are under rapid change, e.g., the Antarctic Peninsula and sub-Antarctic islands.

Study of microdefects and their distribution in dislocation-free Si-doped HB GaAs by X-ray diffuse scattering on triple-crystal diffractometer

NASA Astrophysics Data System (ADS)

Charniy, L. A.; Morozov, A. N.; Bublik, V. T.; Scherbachev, K. D.; Stepantsova, I. V.; Kaganer, V. M.

1992-03-01

Microdefects in dislocation-free Si-doped (n = (1-3) × 10 18cm-3) HB GaAs crystals were studied by X-ray diffuse scattering measured with the help of a triple-crystal diffractometer. The intensity of the diffuse scattering as well as the isointensity contours around different reciprocal lattice points were analysed. A comparison of the measured isointensity contours with the theoretically calculated ones showed that the microdefects detected are interstitial dislocation loops with the Burgers vectors b = {1}/{2}<110 #3862;; lying in the planes #38;{110} and {111}. The mean radius of the dislocation loops R0 was determined using the wave vector q0 alpha; R-10 corresponding to the transmition point where the Huang diffuse scattering I( q) alpha q-2 ( q < q0) changed to the asymptotic scattering I( q) alpha q-4 ( q #62 q0). The analysis of a D-shaped cross-sectional (111) wafer cut from the end part of the HB ingot showed that R0 changed smoothly along the [ overline211] symmetry axis of the wafer. The highly inhomogeneous "new-moon"-like distribution of the non-dislocational etch-pits was also obtained. The maximal loop radius obtained at the edges of the wafer, R 0 = 1 μm, corresponds to the wafer area enriched with etch-pits and the minimal one, R 0 = 0.3 μm, corresponds to the bound of the new-moon-like area denuded from etch-pits. Microdefects of a new type were detected in the denuded area. These microdefects consist of nuclei, 0.1 μm in radius, and an extended atmosphere of interstitials. The minimal microdefect radius in the centre of the wafer corresponds to the maximum local value of the lattice parameter a = 5.655380 Å, and the minimum local value a = 5.65372 Å was obtained at the wafer edges enriched with microdefect-related etch-pits. Absolute X-ray diffuse intensity measurements were used for microdefect concentration determination. Normalization of I( q) was based on the comparison of the Huang intensity with the thermal diffuse scattering intensity which is predominant for the wave vector q å R-10. The microdefect concentration determined in this way appeared to be 4 × 10 9 cm -3 at the edges of the wafer and 4 × 10 11 cm -3 at the centre of the new-moon-like etch-pit denuded zone. The number of interstitial atoms forming dislocation loops is shown to be the same across the area of the wafer and equal to 10 16 cm -3.

The origin of islands in the Kandalaksha Gulf of the White Sea: joint work of internal and external geodynamic processes

NASA Astrophysics Data System (ADS)

Kosevich, Natalia; Romanovskaya, Maria

2016-04-01

The modern White Sea basin is a part of the encounter zone between the East European Platform and of the Fennoscandian Shield. The Kandalaksha Gulf in its northwest lies on the Mesoarchean-Paleoproterozoic structure known as the White Sea Shift Belt. In the Oligocene, it entered its neotectonic stage. Geologically, there are two structural storeys beneath the seafloor of the Kandalaksha Gulf: 1) crystalline bedrock of the Archean White Sea complex; 2) a cover of sediment consisting of three layers: Riphean sandstones, terrigenous Vendian deposits; a cloak of Pleistocene and Holocene deposits and sediments - glacial drifts, transitional glaciomarine sediments and purely marine sediments. The modern White Sea is a young basin formed just 10 to 12 ka. The geological and geomorphic history of the White Sea region was very complicated, with various and often conflicting tectonic movements. Besides the postglacial isostatic rise of Scandinavia amounted to some 100 meters in the White Sea area. The White Sea has numerous islands that are very different in the geological-geomorphological and genetic senses because their origin is the result of interactions between various endogenous and exogenous processes. Large and detailed scale geological and morphological researches of the islands at the southern and northern coast of the Kandalaksha Gulf have been carried out. Landforms of the islands were produced by the joint effects of such processes as (1) glacial-tectonic effects and marine wave action, (2) tidal and surge effects; (3) glacial-tectonic, marine, and gravity effects, and (4) glacial-tectonic, marine, lake, and biogenic effects (Kosevich, 2015). The relief structure of the islands has the following regularities: 1) structures of the northern coast islands are more often landforms that are composed of loose deposits with small sites of structural denudation residual outcrops; 2) the structures of the southern coast islands are typically combinations of loose deposits and bedrock outcrops; structural denudation landforms dominate over the marine and biogenic landforms in this case, rocky surfaces of these islands predominate over others. The relief of islands is a combination of smoothed rounded top bedrock surfaces (massifs) with subhorizontal sites that are covered with loose marine deposits. Analysis of the spatial distribution of the genetic types of islands in the Kandalaksha Gulf has revealed that in the apical part of the gulf all genetic types of islands occur, while upon approaching the mouth, one type (tectonic-glacial-accumulative-denudation with marine reworking) becomes predominant. Thus, geological, structural, geomorphic features of Kandalahksha Gulf islands are the results of the complex interaction of the internal and external geodynamic processes. Kosevich N. Geological-geomorphological types of islands in the Kandalaksha Gulf, White Sea. Moscow Univ. Geol.Bull., 2015, vol. 70, N 4. P. 318-326.

Evaluating hepatocellular carcinoma cell lines for tumour samples using within-sample relative expression orderings of genes.

PubMed

Ao, Lu; Guo, You; Song, Xuekun; Guan, Qingzhou; Zheng, Weicheng; Zhang, Jiahui; Huang, Haiyan; Zou, Yi; Guo, Zheng; Wang, Xianlong

2017-11-01

Concerns are raised about the representativeness of cell lines for tumours due to the culture environment and misidentification. Liver is a major metastatic destination of many cancers, which might further confuse the origin of hepatocellular carcinoma cell lines. Therefore, it is of crucial importance to understand how well they can represent hepatocellular carcinoma. The HCC-specific gene pairs with highly stable relative expression orderings in more than 99% of hepatocellular carcinoma but with reversed relative expression orderings in at least 99% of one of the six types of cancer, colorectal carcinoma, breast carcinoma, non-small-cell lung cancer, gastric carcinoma, pancreatic carcinoma and ovarian carcinoma, were identified. With the simple majority rule, the HCC-specific relative expression orderings from comparisons with colorectal carcinoma and breast carcinoma could exactly discriminate primary hepatocellular carcinoma samples from both primary colorectal carcinoma and breast carcinoma samples. Especially, they correctly classified more than 90% of liver metastatic samples from colorectal carcinoma and breast carcinoma to their original tumours. Finally, using these HCC-specific relative expression orderings from comparisons with six cancer types, we identified eight of 24 hepatocellular carcinoma cell lines in the Cancer Cell Line Encyclopedia (Huh-7, Huh-1, HepG2, Hep3B, JHH-5, JHH-7, C3A and Alexander cells) that are highly representative of hepatocellular carcinoma. Evaluated with a REOs-based prognostic signature for hepatocellular carcinoma, all these eight cell lines showed the same metastatic properties of the high-risk metastatic hepatocellular carcinoma tissues. Caution should be taken for using hepatocellular carcinoma cell lines. Our results should be helpful to select proper hepatocellular carcinoma cell lines for biological experiments. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Method and apparatus for imaging a sample on a device

DOEpatents

Trulson, Mark; Stern, David; Fiekowsky, Peter; Rava, Richard; Walton, Ian; Fodor, Stephen P. A.

2001-01-01

A method and apparatus for imaging a sample are provided. An electromagnetic radiation source generates excitation radiation which is sized by excitation optics to a line. The line is directed at a sample resting on a support and excites a plurality of regions on the sample. Collection optics collect response radiation reflected from the sample I and image the reflected radiation. A detector senses the reflected radiation and is positioned to permit discrimination between radiation reflected from a certain focal plane in the sample and certain other planes within the sample.

Toxicological Evaluation of Realistic Emission Source Aerosols (TERESA): Introduction and overview

PubMed Central

Godleski, John J.; Rohr, Annette C.; Kang, Choong M.; Diaz, Edgar A.; Ruiz, Pablo A.; Koutrakis, Petros

2013-01-01

Determining the health impacts of sources and components of fine particulate matter (PM2.5) is an important scientific goal. PM2.5 is a complex mixture of inorganic and organic constituents that are likely to differ in their potential to cause adverse health outcomes. The Toxicological Evaluation of Realistic Emissions of Source Aerosols (TERESA) study focused on two PM sources—coal-fired power plants and mobile sources—and sought to investigate the toxicological effects of exposure to emissions from these sources. The set of papers published here document the power plant experiments. TERESA attempted to delineate health effects of primary particles, secondary (aged) particles, and mixtures of these with common atmospheric constituents. TERESA involved withdrawal of emissions from the stacks of three coal-fired power plants in the United States. The emissions were aged and atmospherically transformed in a mobile laboratory simulating downwind power plant plume processing. Toxicological evaluations were carried out in laboratory rats exposed to different emission scenarios with extensive exposure characterization. The approach employed in TERESA was ambitious and innovative. Technical challenges included the development of stack sampling technology that prevented condensation of water vapor from the power plant exhaust during sampling and transfer, while minimizing losses of primary particles; development and optimization of a photochemical chamber to provide an aged aerosol for animal exposures; development and evaluation of a denuder system to remove excess gaseous components; and development of a mobile toxicology laboratory. This paper provides an overview of the conceptual framework, design, and methods employed in the study. PMID:21639692

[The research on separating and extracting overlapping spectral feature lines in LIBS using damped least squares method].

PubMed

Wang, Yin; Zhao, Nan-jing; Liu, Wen-qing; Yu, Yang; Fang, Li; Meng, De-shuo; Hu, Li; Zhang, Da-hai; Ma, Min-jun; Xiao, Xue; Wang, Yu; Liu, Jian-guo

2015-02-01

In recent years, the technology of laser induced breakdown spectroscopy has been developed rapidly. As one kind of new material composition detection technology, laser induced breakdown spectroscopy can simultaneously detect multi elements fast and simply without any complex sample preparation and realize field, in-situ material composition detection of the sample to be tested. This kind of technology is very promising in many fields. It is very important to separate, fit and extract spectral feature lines in laser induced breakdown spectroscopy, which is the cornerstone of spectral feature recognition and subsequent elements concentrations inversion research. In order to realize effective separation, fitting and extraction of spectral feature lines in laser induced breakdown spectroscopy, the original parameters for spectral lines fitting before iteration were analyzed and determined. The spectral feature line of' chromium (Cr I : 427.480 nm) in fly ash gathered from a coal-fired power station, which was overlapped with another line(FeI: 427.176 nm), was separated from the other one and extracted by using damped least squares method. Based on Gauss-Newton iteration, damped least squares method adds damping factor to step and adjust step length dynamically according to the feedback information after each iteration, in order to prevent the iteration from diverging and make sure that the iteration could converge fast. Damped least squares method helps to obtain better results of separating, fitting and extracting spectral feature lines and give more accurate intensity values of these spectral feature lines: The spectral feature lines of chromium in samples which contain different concentrations of chromium were separated and extracted. And then, the intensity values of corresponding spectral lines were given by using damped least squares method and least squares method separately. The calibration curves were plotted, which showed the relationship between spectral line intensity values and chromium concentrations in different samples. And then their respective linear correlations were compared. The experimental results showed that the linear correlation of the intensity values of spectral feature lines and the concentrations of chromium in different samples, which was obtained by damped least squares method, was better than that one obtained by least squares method. And therefore, damped least squares method was stable, reliable and suitable for separating, fitting and extracting spectral feature lines in laser induced breakdown spectroscopy.

Conodont color alteration index and upper Paleozoic thermal history of the Amazonas Basin, Brazil

NASA Astrophysics Data System (ADS)

Cardoso, Cassiane Negreiros; Sanz-López, Javier; Blanco-Ferrera, Silvia; Lemos, Valesca Brasil; Scomazzon, Ana Karina

2015-12-01

The conodont color alteration index (CAI) was determined in elements from core samples of the Frasnian Barreirinha Formation (one well) and of the Pennsylvanian-Permian Tapajós Group (twenty three wells and one limestone quarry) in the Amazonas Basin. The thermal history of the basin is analyzed using the CAI value distribution represented in maps and stratigraphic sections through correlation schemes, and in conjunction with previously published data. The pattern of palaeotemperatures for CAI values of 1.5-3 is coincident with organic matter maturation under a sedimentary overburden providing diagenetic conditions in the oil/gas window. Locally, conodonts show metamorphism (CAI value of 6-7) in relation to the intrusion of diabase bodies in beds including high geothermal gradient evaporites. Microtextural alteration on the surface conodonts commonly shows several types of overgrowth microtextures developed in diagenetic conditions. Locally, recrystallization in conodonts with a high CAI value is congruent with contact metamorphism in relation to Mesozoic intrusions. The CAI values of 1.5 or 2 observed close to the surface in several areas of the basin may be interpreted in relation to a high thermal palaeogradient derived from the magmatic episode or/and to the local denudation of the upper part of the Paleozoic succession prior to this thermal event.

Decreased expression of zonula occludens-1 and occludin in the bladder urothelium of patients with interstitial cystitis/painful bladder syndrome.

PubMed

Lee, Jane-Dar; Lee, Ming-Huei

2014-01-01

Unique barrier properties of the urothelial surface membrane permit urine storage without contents leak into the bloodstream. Previous reports suggested that the bladder urothelial barrier might be compromised in interstitial cystitis/painful bladder syndrome (IC/PBS). We examined the changes of tight junction proteins (zonula occludens-1 (ZO-1) and occludin) in IC/PBS patients. Bladder samples were derived from of 32 patients with IC/PBS and eight controls. We detected the tight junction proteins of ZO-1 and occludin expression by immunoblotting, immunohistochemical (IHC) staining and double immunofluorescent (IF) staining with confocal microscopy. Data were analyzed using the Mann-Whitney U-test. Expression of ZO-1 and occludin in the IC/PBS group was reduced compared to the control group by immunoblotting and IHC staining. Also, the thinning and denudation of urothelium were demonstrated in the IC/PBS group by histological study. IF staining showed the interruption of bladder urothelium in IC/PBS patients under confocal microscopy. Our data showed that decreased expression of tight junction proteins (ZO-1 and occludin) and interruption of bladder urothelium in IC/PBS patients. Treatment to repair the discontinuous urothelium may be useful to relieve some clinical symptoms of patients with IC/PBS. Copyright © 2012. Published by Elsevier B.V.

Hanging drop monoculture for selection of optimal antioxidants during in vitro maturation of porcine oocytes.

PubMed

Ishikawa, S; Machida, R; Hiraga, K; Hiradate, Y; Suda, Y; Tanemura, K

2014-04-01

We analysed the effect of three antioxidants that have different functional mechanisms on the in vitro maturation (IVM) of porcine oocytes. Single oocyte monoculture using the hanging drop (HD) system has some advantages such as improving analysis efficiency brought by the smaller number of samples than the number of oocytes cultured in one drop. Direct effects of ligands on single oocytes could also be detected without considering the effects of paracrine factors from other oocytes. After 22 h of pre-culture, denuded oocytes were cultured for 22 h with 0.01 and 0.1 μg/ml of L-carnitine (LC), lactoferrin (LF) or sulforaphane (SF) in the presence/non-presence of oxidant stress induced by H2O2 supplementation to evaluate the reducing effects against oxidative stress on nuclear maturation. As a result, compared with LC and SF, LF showed effective reduction in oxidative stress at a lower concentration (0.01 μg/ml), suggesting that LF is a more effective antioxidant in porcine oocyte IVM. Additionally, LF also increased maturation rate even in culture without H2O2. Our results clearly suggest that the HD monoculture system is useful for screening the substances that affect porcine oocyte culture. © 2014 Blackwell Verlag GmbH.

Enhanced Particulate Organic Carbon Export at Eddy Edges in the Oligotrophic Western North Pacific Ocean

PubMed Central

Shih, Yung-Yen; Hung, Chin-Chang; Gong, Gwo-Ching; Chung, Wan-Chen; Wang, Yu-Huai; Lee, I-Huan; Chen, Kuo-Shu; Ho, Chuang-Yi

2015-01-01

Mesoscale eddies in the subtropical oligotrophic ocean are ubiquitous and play an important role in nutrient supply and oceanic primary production. However, it is still unclear whether these mesoscale eddies can efficiently transfer CO2 from the atmosphere to deep waters via biological pump because of the sampling difficulty due to their transient nature. In 2007, particulate organic carbon (POC) fluxes, measured below the euphotic zone at the edge of warm eddy were 136–194 mg-C m−2 d−1 which was greatly elevated over that (POC flux = 26–35 mg-C m−2 d−1) determined in the nutrient-depleted oligotrophic waters in the Western North Pacific (WNP). In 2010, higher POC fluxes (83–115 mg-C m−2 d−1) were also observed at the boundary of mesoscale eddies in the WNP. The enhanced POC flux at the edge of eddies was mainly attributed to both large denuded diatom frustules and zooplankton fecal pellets based on scanning electron microscopy (SEM) examination. The result suggests that mesoscale eddies in the oligotrophic waters in the subtropical WNP can efficiently increase the oceanic carbon export flux and the eddy edge is a crucial conduit in carbon sequestration to deep waters. PMID:26171611

Measurement of pattern roughness and local size variation using CD-SEM: current status

NASA Astrophysics Data System (ADS)

Fukuda, Hiroshi; Kawasaki, Takahiro; Kawada, Hiroki; Sakai, Kei; Kato, Takashi; Yamaguchi, Satoru; Ikota, Masami; Momonoi, Yoshinori

2018-03-01

Measurement of line edge roughness (LER) is discussed from four aspects: edge detection, PSD prediction, sampling strategy, and noise mitigation, and general guidelines and practical solutions for LER measurement today are introduced. Advanced edge detection algorithms such as wave-matching method are shown effective for robustly detecting edges from low SNR images, while conventional algorithm with weak filtering is still effective in suppressing SEM noise and aliasing. Advanced PSD prediction method such as multi-taper method is effective in suppressing sampling noise within a line edge to analyze, while number of lines is still required for suppressing line to line variation. Two types of SEM noise mitigation methods, "apparent noise floor" subtraction method and LER-noise decomposition using regression analysis are verified to successfully mitigate SEM noise from PSD curves. These results are extended to LCDU measurement to clarify the impact of SEM noise and sampling noise on LCDU.

Antiproliferative effects of the readily extractable fractions prepared from various citrus juices on several cancer cell lines.

PubMed

Kawaii, S; Tomono, Y; Katase, E; Ogawa, K; Yano, M

1999-07-01

To eliminate the masking effect by flavonoid glycosides, which comprise approximately 70% of conventionally prepared sample, the readily extractable fraction from Citrus juice, which was prepared by adsorbing on HP-20 resin and eluting with ethanol and acetone from the resin, was subjected to antiproliferative tests against several cancer cell lines. Screening of 34 Citrus juices indicated that King (Citrus nobilis) strongly inhibited proliferation of all cancer cell lines examined. Sweet lime and Kabuchi inhibited three of the four cancer cell lines. In contrast, these samples were substantially less cytotoxic toward normal human cell lines.

Method for Hot Real-Time Sampling of Gasification Products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pomeroy, Marc D

The Thermochemical Process Development Unit (TCPDU) at the National Renewable Energy Laboratory (NREL) is a highly instrumented half-ton/day pilot scale plant capable of demonstrating industrially relevant thermochemical technologies from lignocellulosic biomass conversion, including gasification. Gasification creates primarily Syngas (a mixture of Hydrogen and Carbon Monoxide) that can be utilized with synthesis catalysts to form transportation fuels and other valuable chemicals. Biomass derived gasification products are a very complex mixture of chemical components that typically contain Sulfur and Nitrogen species that can act as catalysis poisons for tar reforming and synthesis catalysts. Real-time hot online sampling techniques, such as Molecular Beammore » Mass Spectrometry (MBMS), and Gas Chromatographs with Sulfur and Nitrogen specific detectors can provide real-time analysis providing operational indicators for performance. Sampling typically requires coated sampling lines to minimize trace sulfur interactions with steel surfaces. Other materials used inline have also shown conversion of sulfur species into new components and must be minimized. Sample line Residence time within the sampling lines must also be kept to a minimum to reduce further reaction chemistries. Solids from ash and char contribute to plugging and must be filtered at temperature. Experience at NREL has shown several key factors to consider when designing and installing an analytical sampling system for biomass gasification products. They include minimizing sampling distance, effective filtering as close to source as possible, proper line sizing, proper line materials or coatings, even heating of all components, minimizing pressure drops, and additional filtering or traps after pressure drops.« less

In-line real time air monitor

DOEpatents

Wise, Marcus B.; Thompson, Cyril V.

1998-01-01

An in-line gas monitor capable of accurate gas composition analysis in a continuous real time manner even under strong applied vacuum conditions operates by mixing an air sample with helium forming a sample gas in two complementary sample loops embedded in a manifold which includes two pairs of 3-way solenoid valves. The sample gas is then analyzed in an ion trap mass spectrometer on a continuous basis. Two valve drivers actuate the two pairs of 3-way valves in a reciprocating fashion, so that there is always flow through the in-line gas monitor via one or the other of the sample loops. The duty cycle for the two pairs of 3-way valves is varied by tuning the two valve drivers to a duty cycle typically between 0.2 to 0.7 seconds.

99. LIQUID OXYGEN LINE AND SAMPLING VALVE FOR RAPIDLOAD ON ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

99. LIQUID OXYGEN LINE AND SAMPLING VALVE FOR RAPID-LOAD ON WEST SIDE OF SKID 9A - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

Prevalence of genetically modified rice, maize, and soy in Saudi food products.

PubMed

Elsanhoty, Rafaat M; Al-Turki, A I; Ramadan, Mohamed Fawzy

2013-10-01

Qualitative and quantitative DNA-based methods were applied to detect genetically modified foods in samples from markets in the Kingdom of Saudi Arabia. Two hundred samples were collected from Al-Qassim, Riyadh, and Mahdina in 2009 and 2010. GMOScreen 35S and NOS test kits for the detection of genetically modified organism varieties in samples were used. The positive results obtained from GMOScreen 35S and NOS were identified using specific primer pairs. The results indicated that all rice samples gave negative results for the presence of 35S and NOS terminator. About 26 % of samples containing soybean were positive for 35S and NOS terminator and 44 % of samples containing maize were positive for the presence of 35S and/or NOS terminator. The results showed that 20.4 % of samples was positive for maize line Bt176, 8.8 % was positive for maize line Bt11, 8.8 % was positive for maize line T25, 5.9 % was positive for maize line MON 810, and 5.9 % was positive for StarLink maize. Twelve samples were shown to contain <3 % of genetically modified (GM) soy and 6 samples >10 % of GM soy. Four samples containing GM maize were shown to contain >5 % of GM maize MON 810. Four samples containing GM maize were shown to contain >1 % of StarLink maize. Establishing strong regulations and certified laboratories to monitor GM foods or crops in Saudi market is recommended.

MetNH3: Metrology for ammonia in ambient air

NASA Astrophysics Data System (ADS)

Braban, Christine; Twigg, Marsailidh; Tang, Sim; Leuenberger, Daiana; Ferracci, Valerio; Martin, Nick; Pascale, Celine; Hieta, Tuomas; Pogany, Andrea; Persijn, Stefan; van Wijk, Janneke; Gerwig, Holger; Wirtze, Klaus; Tiebe, Carlo; Balslev-Harder, David; Niederhausen, Bernhardt

2015-04-01

Measuring ammonia in ambient air is a sensitive and priority issue due to its harmful effects on human health and ecosystems. The European Directive 2001/81/EC on 'National Emission Ceilings for Certain Atmospheric Pollutants (NEC)' regulates ammonia emissions in the member states. However, there is a lack of regulation to ensure reliable ammonia measurements namely in applicable analytical technology, maximum allowed uncertainty, quality assurance and quality control (QC/QA) procedures as well as in the infrastructure to attain metrological traceability. Validated ammonia measurement data of high quality from air monitoring networks are vitally important for identifying changes due to implementations of environment policies, for understanding where the uncertainties in current emission inventories are derived from and for providing independent verification of atmospheric model predictions. The new EURAMET project MetNH3 aims to develop improved reference gas mixtures by static and dynamic gravimetric generation methods, develop and characterise laser based optical spectrometric standards and establish the transfer from high-accuracy standards to field applicable methods. MetNH3started in June 2014 and in this presentation the first results from the metrological characterisation of a commercially available cavity ring-down spectrometer (CRDS) will be discussed. Also first tests and results from a new design, Controlled Atmosphere Test Facility (CATFAC), which is to be characterised and used to validate the performance of diffusive samplers, denuders and on-line instruments, will be reported. CAFTEC can be used to control test parameters such as ammonia concentration, relative humidity and wind speed. Outline plans for international laboratory and field intercomparisons in 2016 will be presented.

Polyamine-dependent migration of retinal pigment epithelial cells.

PubMed

Johnson, Dianna A; Fields, Carolyn; Fallon, Amy; Fitzgerald, Malinda E C; Viar, Mary Jane; Johnson, Leonard R

2002-04-01

Migration of retinal pigment epithelial (RPE) cells can be triggered by disruption of the RPE monolayer or injury to the neural retina. Migrating cells may re-establish a confluent monolayer, or they may invade the neural retina and disrupt visual function. The purpose of this study was to examine the role of endogenous polyamines in mechanisms of RPE migration. Endogenous polyamine levels were determined in an immortalized RPE cell line, D407, using HPLC. Activities of the two rate-limiting enzymes for polyamine synthesis, ornithine decarboxylase (ODC), and S-adenosylmethionine decarboxylase (SAMdc), were measured by liberation of ((14)CO(2))(.) Migration was assessed in confluent cultures by determining the number of cells migrating into a mechanically denuded area. All measurements were obtained both in control cultures and in cultures treated with synthesis inhibitors that deplete endogenous polyamines. Subcellular localization of endogenous polyamines was determined using a polyamine antibody. The polyamines, spermidine and spermine, as well as their precursor, putrescine, were normal constituents of RPE cells. The two rate-limiting synthetic enzymes were also present, and their activities were stimulated dramatically by addition of serum to the culture medium. Cell migration was similarly stimulated by serum exposure. When endogenous polyamines were depleted, migration was blocked. When polyamines were replenished through uptake, migration was restored. Polyamine immunoreactivity was limited to membrane patches in quiescent cells. In actively migrating and dividing cells, immunoreactivity was enhanced throughout the cytoplasm. Polyamines are essential for RPE migration. Pharmacologic manipulation of the polyamine pathway could provide a therapeutic strategy for regulating anomalous migration.

Improved cryotolerance and developmental potential of in vitro and in vivo matured mouse oocytes by supplementing with a glutathione donor prior to vitrification.

PubMed

Trapphoff, Tom; Heiligentag, Martyna; Simon, Jenny; Staubach, Nora; Seidel, Thorsten; Otte, Kathrin; Fröhlich, Thomas; Arnold, Georg J; Eichenlaub-Ritter, Ursula

2016-12-01

Can supplementation of media with a glutathione (GSH) donor, glutathione ethyl ester (GEE), prior to vitrification protect the mouse oocyte from oxidative damage and critical changes in redox homeostasis, and thereby improve cryotolerance? GEE supplementation supported redox regulation, rapid recovery of spindle and chromosome alignment after vitrification/warming and improved preimplantation development of mouse metaphase II (MII) oocytes. Cryopreservation may affect mitochondrial functionality, induce oxidative stress, and thereby affect spindle integrity, chromosome segregation and the quality of mammalian oocytes. GEE is a membrane permeable GSH donor that promoted fertilization and early embryonic development of macaque and bovine oocytes after IVM. Two experimental groups consisted of (i) denuded mouse germinal vesicle (GV) oocytes that were matured in vitro in the presence or absence of 1 mM GEE (IVM group 1) and (ii) in vivo ovulated (IVO) MII oocytes that were isolated from the ampullae and exposed to 1 mM GEE for 1 h prior to vitrification (IVO group 2). Recovery of oocytes from both groups was followed after CryoTop vitrification/warming for up to 2 h and parthenogenetic activation. Reactive oxygen species (ROS), spindle morphology and chromosome alignment were analyzed by confocal laser scanning microscopy (CLSM) and polarization microscopy in control and GEE-supplemented MII oocytes. The relative overall intra-oocyte GSH content was assessed by analysis of monochlorobimane (MBC)-GSH adduct fluorescence in IVM MII oocytes. The GSH-dependent intra-mitochondrial redox potential (E m GSH ) of IVM MII oocytes was determined after microinjection with specific mRNA at the GV stage to express a redox-sensitive probe within mitochondria (mito-Grx1-roGFP2). The absolute negative redox capacity (in millivolts) was determined by analysis of fluorescence of the oxidized versus the reduced form of sensor by CLSM and quantification according to Nernst equation. Proteome analysis was performed by quantitative 2D saturation gel electrophoresis (2D DIGE). Since microinjection and expression of redox sensor mRNA required removal of cumulus cells, and IVM of denuded mouse oocytes in group 1 induces zona hardening, the development to blastocysts was not assessed after IVF but instead after parthenogenetic activation of vitrified/warmed MII oocytes from both experimental groups. IVM of denuded mouse oocytes in the presence of 1 mM GEE significantly increased intra-oocyte GSH content. ROS was not increased by CryoTop vitrification but was significantly lower in the IVM GEE group compared to IVM without GEE before vitrification and after recovery from vitrification/warming (P < 0.001). Vitrification alone significantly increased the GSH-dependent intra-mitochondrial redox capacity after warming (E m GSH , P < 0.001) in IVM oocytes, presumably by diffusion/uptake of cytoplasmic GSH into mitochondria. The presence of 1 mM GEE during IVM increased the redox capacity before vitrification and there was no further increase after vitrification/warming. None of the reproducibly detected 1492 spots of 2D DIGE separated proteins were significantly altered by vitrification or GEE supplementation. However, IVM of denuded oocytes significantly affected spindle integrity and chromosome alignment right after warming from vitrification (0 h) in group 1 and spindle integrity in group 2 (P < 0.05). GEE improved recovery in IVM group as numbers of oocytes with unaligned chromosomes and aberrant spindles was not significantly increased compared to unvitrified controls. The supplementation with GEE for 1 h before vitrification also supported more rapid recovery of spindle birefringence. GEE improved significantly development to the 2-cell stage for MII oocytes that were activated directly after vitrification/warming in both experimental groups, and also the blastocyst rate in the IVO GEE-supplemented group compared to the controls (P < 0.05). None LIMITATIONS, REASONS FOR CAUTION: The studies were carried out in a mouse model, in IVM denuded rather than cumulus-enclosed oocytes, and in activated rather than IVF MII oocytes. Whether the increased GSH-dependent intra-mitochondrial redox capacity also improves male pronuclear formation needs to be studied further experimentally. The influence of GEE supplementation requires also further examination and optimization in human oocytes before it can be considered for clinical ART. Although GEE supplementation did not alter the proteome at MII, the GSH donor may support cellular homeostasis and redox regulation and, thus, increase developmental competence. While human MII oocyte vitrification is an established procedure, GEE might be particularly beneficial for oocytes that suffer from oxidative stress and reduced redox capacity (e.g. aged oocytes) or possess low GSH due to a reduced supply of GSH from cumulus. It might also be of relevance for immature human oocytes that develop without cumulus to MII in vitro (e.g. in ICSI cycles) for ART. The study has been supported by the German Research Foundation (DFG FOR 1041; EI 199/3-2). There are no conflict of interests. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Atmospheric transformation of diesel emissions.

PubMed

Zielinska, Barbara; Samy, Shar; McDonald, Jacob D; Seagrave, JeanClare

2010-04-01

The hypothesis of this study was that exposing diesel exhaust (DE*) to the atmosphere transforms its composition and toxicity. Our specific aims were (1) to characterize the gas- and particle-phase products of atmospheric transformations of DE under the influence of daylight, ozone (O3), hydroxyl (OH) radicals, and nitrate (NO3) radicals; and (2) to explore the biologic activity of DE before and after the transformations took place. The study was executed with the aid of the EUPHORE (European Photoreactor) outdoor simulation chamber facility in Valencia, Spain. EUPHORE is one of the largest and best-equipped facilities of its kind in the world, allowing investigation of atmospheric transformation processes under realistic ambient conditions (with dilutions in the range of 1:300). DE was generated on-site using a modern light-duty diesel engine and a dynamometer system equipped with a continuous emission-gas analyzer. The engine (a turbocharged, intercooled model with common-rail direct injection) was obtained from the Ford Motor Company. A first series of experiments was carried out in January 2005 (the winter 2005 campaign), a second in May 2005 (the summer 2005 campaign), and a third in May and June 2006 (the summer 2006 campaign). The diesel fuel that was used closely matched the one currently in use in most of the United States (containing 47 ppm sulfur and 15% aromatic compounds). Our experiments examined the effects on the composition of DE aged in the dark with added NO3 radicals and of DE aged in daylight with added OH radicals both with and without added volatile organic compounds (VOCs). In order to remove excess nitrogen oxides (NO(x)), a NO(x) denuder was devised and used to conduct experiments in realistic low-NO(x) conditions in both summer campaigns. A scanning mobility particle sizer was used to determine the particle size and the number and volume concentrations of particulate matter (PM) in the DE. O3, NO(x), and reactive nitrogen oxides (NO(y)) were monitored using chemiluminescence and Fourier transform infrared instruments. At the end of the exposures, samples of particle-associated and semivolatile organic compounds (SVOCs) were collected from the chamber for chemical analysis using an XAD-coated annular denuder followed by a filter and XAD cartridge. (XAD is an adsorbent polystyrene divinylbenzene resin used in sampling cartridges.) Samples for toxicity testing were collected using Teflon filters followed by two XAD cartridges. The chemical analyses included determination of organic carbon (OC), elemental carbon (EC), carbon fractions, inorganic ions (e.g., sulfate and nitrate), and speciated organic compounds (polycyclic aromatic hydrocarbons [PAHs], nitro-PAHs, polar compounds, alkanes, hopanes, and steranes). The toxicity tests were performed with extracts of PM combined with the SVOCs. The biologic activity of these extracts was evaluated in vivo by instilling them into the tracheas of rodents and measuring pulmonary toxicity, inflammation, and oxidative-stress responses. Results from the chemical analyses indicated that aging DE in the dark with added NO3 radicals and aging DE in daylight with and without additions led to the formation of additional particles and SVOC mass caused by reactions of VOCs, SVOCs, and inorganic gases. The greatest increase in mass occurred with the addition of VOCs as co-reactants. The proportions of the pyrolized OC (POC) fraction increased in the organic mass, which suggested that highly polar and oligomeric compounds had been formed. Results from the toxicity testing were consistent with the hypothesis that the toxicity of the samples had been affected by changes in their composition (caused both by the atmospheric aging and by changes in the initial composition of the DE presumably associated with changes in the engine, which was new at the outset and accrued wear during the study).

Sichuan Basin and beyond: Eastward foreland growth of the Tibetan Plateau from an integration of Late Cretaceous-Cenozoic fission track and (U-Th)/He ages of the eastern Tibetan Plateau, Qinling, and Daba Shan

NASA Astrophysics Data System (ADS)

Yang, Zhao; Shen, Chuanbo; Ratschbacher, Lothar; Enkelmann, Eva; Jonckheere, Raymond; Wauschkuhn, Bastian; Dong, Yunpeng

2017-06-01

Combining 121 new fission track and (U-Th)/He ages with published thermochronologic data, we investigate the Late Cretaceous-Cenozoic exhumation/cooling history of the eastern Tibetan Plateau, Qinling, Daba Shan, and Sichuan Basin of east central China. The Qinling orogen shows terminal southwestward foreland growth in the northern Daba Shan thrust belt at 100-90 Ma and in the southern Daba Shan fold belt at 85-70 Ma. The eastern margin of Tibetan Plateau experienced major exhumation phases at 70-40 Ma (exhumation rate 0.05-0.08 mm/yr), 25-15 Ma (≤1 mm/yr in the Pengguan Massif; 0.2 mm/yr in the imbricated western Sichuan Basin), and since 11-10 Ma along the Longmen Shan ( 0.80 mm/yr) and the interior of the eastern Tibetan Plateau (Dadu River gorge, Min Shan; 0.50 mm/yr). The Sichuan Basin records two basin-wide denudation phases, likely a result of the reorganization of the upper Yangtze River drainage system. The first phase commenced at 45 Ma and probably ended before the Miocene; >1 km of rocks were eroded from the central and eastern Sichuan Basin. The second phase commenced at 12 Ma and denudated the central Sichuan Basin, Longmen Shan, and southern Daba Shan; more than 2 km of rocks were eroded after the lower Yangtze River had cut through the Three Gorges and captured the Sichuan Basin drainage. In contrast to the East Qinling, which was weakly effected by late Cenozoic exhumation, the West Qinling and Daba Shan have experienced rapid exhumation/cooling since 15-13 Ma, a result of growth of the Tibetan Plateau beyond the Sichuan Basin.

Apixaban Enhances Vasodilatation Mediated by Protease-Activated Receptor 2 in Isolated Rat Arteries

PubMed Central

Villari, Ambra; Giurdanella, Giovanni; Bucolo, Claudio; Drago, Filippo; Salomone, Salvatore

2017-01-01

Apixaban (APX) is a direct inhibitor of factor X (FXa) approved for prophylaxis and treatment of deep venous thrombosis and atrial fibrillation. Because FXa activates protease-activated receptor 2 (PAR-2) in endothelium and vascular smooth muscle, inhibition of FXa by APX may affect vasomotor function. The effect of APX was assessed in vitro, by wire myography, in rat mesenteric resistance arteries (MRAs) and basilar arteries challenged with vasoconstrictors [phenylephrine (PE); 5-hydroxytryptamine (5-HT)], vasodilators [acetylcholine (ACh); sodium nitroprusside (SNP)] or with the PAR-2 peptide agonist SLIGRL. APX (10 μM) reduced the vasoconstriction to PE and 5-HT while did not change the vasodilatation to ACh or SNP. SLIGRL induced concentration-dependent vasodilation in pre-constricted arteries, that was reduced by incubation with the NO inhibitor NG-nitro-L-arginine (L-NNA) and abolished by endothelium removal. APX enhanced vasodilation to SLIGRL either in the presence or in the absence of L-NNA, but was ineffective in endothelium-denuded vessels. In preparations from heparin-treated rats (to inhibit FXa) APX did not change the vasodilation to SLIGRL. FXa enzymatic activity, detected in mesentery homogenates from controls, was inhibited by APX, whereas APX-sensitive enzymatic activity was undetectable in homogenates from heparin-treated rats. Immunoblot analysis showed that incubation of MRA or aorta with APX increased the abundance of PAR-2, an effect not seen in MRA from heparin-treated rats or in endothelium-denuded aortas. In conclusion, inhibition of FXa by APX increases vasodilatation mediated by PAR-2. APX may act by inhibiting PAR-2 desensitization induced by endogenous FXa. This effect could be useful in the context of endothelial dysfunction associated to cardiovascular diseases. PMID:28769809

Evaluation of the Distribution of Paclitaxel After Application of a Paclitaxel-Coated Balloon in the Rabbit Urethra.

PubMed

Barbalias, Dimitrios; Lappas, Georgios; Ravazoula, Panagiotia; Liourdi, Despoina; Kyriazis, Iason; Liatsikos, Evangelos; Kallidonis, Panagiotis

2018-05-01

Urethral strictures are a common urologic problem that could require complex reconstructive procedures. Urethral dilatation represents a frequent practiced intervention associated with high recurrence rates. Drug-coated percutaneous angioplasty balloons (DCBs) with cytostatic drugs have been effectively used for the prevention of vascular restenosis after balloon dilatation. To reduce restenosis rates of urethral dilatation, these balloons could be used in the urethra. Nevertheless, the urothelium is different than the endothelium and these drugs may not be distributed to the outer layers of the urethra. Thus, an experiment was performed to evaluate the distribution of paclitaxel (PTX) in the rabbit urethra after the inflation of a PTX-coated balloon (PCB). Eleven rabbits underwent dilatation of the posterior urethra with common endoscopic balloons after urethrography. Nine of these rabbits were additionally treated with PCB. The urethras of the two control animals were removed along with three more dilated with PCB urethras immediately after the dilatation. The remaining of the urethras were removed after 24 (n = 3) and 48 hours (n = 3). The posterior segments of the urethras were evaluated with hematoxylin and eosin staining as well as with immunohistochemistry with polyclonal anti-PTX antibody. The two control specimens showed denudation of the urothelium after balloon dilatations and no PTX was observed. All specimens from dilated PCB urethras showed distribution of PTX to all layers of the urethra. The specimens that were immediately removed exhibited denudation of the urothelium without any inflammation. The specimens removed at 24 and 48 hours showed mild acute inflammation. PTX was distributed to the urothelial, submucosal, and smooth muscle layers of the normal rabbit urethra immediately after dilatation with a DCB. PTX and mild inflammation were present at the site 24 and 48 hours after the dilatation.

Geochemical Responses to Anthropogenic and Natural Influences in Ebinur Lake Sediments of Arid Northwest China.

PubMed

Ma, Long; Wu, Jinglu; Abuduwaili, Jilili; Liu, Wen

2016-01-01

Geochemical concentrations were extracted for a short sediment core from Ebinur Lake, located in arid northwest China, and mathematical methods were used to demonstrate the complex pattern of the geochemical anomalies resulting from the temporal changes in natural and anthropogenic forces on the lake sediments. The first element assemblage (C1) (aluminum, potassium, iron, magnesium, beryllium, etc.) was predominantly terrigenous; among the assemblage, total phosphorus and titanium were generally consistent with aluminum except with regards to their surface sequences, which inferred the differences of source regions for terrigenous detrital material led to this change around ca. 2000AD. The second assemblage (C2) (calcium and strontium) was found to have a negative relationship with aluminum through a cluster analysis. The third assemblage (C3) included sodium and magnesium, which were influenced by the underwater lake environment and deposited in the Ebinur depression. The concentration ratio of C1/(C1+C2) was used as an indicator for denudation amount of detrital materials, which was supported by the values of magnetic susceptibility. The enrichment factors for heavy metals suggested that the influence of human activities on heavy-metal enrichment in Ebinur Lake region was not severe over the past century. Prior to the 1960s, geochemical indicators suggested a stable lacustrine environment with higher water levels. Beginning in the 1960s, high agricultural water demand resulted in rapid declines in lake water level, with subsequent increases of lake water salinity, as evidenced by enhanced sodium concentration in lake core sediments. During this period, anthropogenic activity also enhanced the intensity of weathering and the denudation of the Ebinur watershed.

α1- and α2-Adrenergic responsiveness in human skeletal muscle feed arteries: the role of TRPV ion channels in heat-induced sympatholysis

PubMed Central

Gifford, Jayson R.; Ives, Stephen J.; Park, Song-Young; Andtbacka, Robert H. I.; Hyngstrom, John R.; Mueller, Michelle T.; Treiman, Gerald S.; Ward, Christopher; Trinity, Joel D.

2014-01-01

The purpose of this study was to determine if heat inhibits α2-adrenergic vasocontraction, similarly to α1-adrenergic contraction, in isolated human skeletal muscle feed arteries (SMFA) and elucidate the role of the temperature-sensitive vanilloid-type transient receptor potential (TRPV) ion channels in this response. Isolated SMFA from 37 subjects were studied using wire myography. α1 [Phenylephrine (PE)]- and α2 [dexmedetomidine (DEX)]-contractions were induced at 37 and 39°C with and without TRPV family and TRPV4-specific inhibition [ruthenium red (RR) and RN-1734, respectively]. Endothelial function [acetylcholine (ACh)] and smooth muscle function [sodium nitroprusside (SNP) and potassium chloride (KCl)] were also assessed under these conditions. Heat and TRPV inhibition was further examined in endothelium-denuded arteries. Contraction data are reported as a percentage of maximal contraction elicited by 100 mM KCl (LTmax). DEX elicited a small and variable contractile response, one-fifth the magnitude of PE, which was not as clearly attenuated when heated from 37 to 39°C (12 ± 4 to 6 ± 2% LTmax; P = 0.18) as were PE-induced contractions (59 ± 5 to 24 ± 4% LTmax; P < 0.05). Both forms of TRPV inhibition restored PE-induced contraction at 39°C (P < 0.05) implicating these channels, particularly the TRPV4 channels, in the heat-induced attenuation of α1-adrenergic vasocontraction. TRPV inhibition significantly blunted ACh relaxation while denudation prevented heat-induced sympatholysis without having an additive effect when combined with TRPV inhibition. In conclusion, physiological increases in temperature elicit a sympatholysis-like inhibition of α1-adrenergic vasocontraction in human SMFA that appears to be mediated by endothelial TRPV4 ion channels. PMID:25172894

Cinematic modeling of local morphostructures evolution

NASA Astrophysics Data System (ADS)

Bronguleev, Vadim

2013-04-01

With the use of a simple 3-dimensional cinematic model of slope development some characteristic features of morphostructure evolution were shown. We assume that the velocity of slope degradation along normal vector to a surface is determined by three morphological parameters: slope angle, its profile curvature and its plan curvature. This leads to the equation of parabolic type: where h=h(x,y,t) is the altitude of slope surface, Kpr(x,y,t)is the profile curvature of the slope, Kpl(x,y,t) is the plan curvature, f(x,y,t) is the velocity of tectonic deformation (or base level movement), A, B, and C are the coefficients which may depend on coordinates and time. The first term in the right part of the equation describes parallel slope retreat, typical to arid environment, the second term describes slope vertical grading due to viscous flow, typical to humid conditions, and the third term is responsible for slope plan grading due to such processes as desquamation, frost weathering, etc. This simple model describes a wide range of local morphostructures evolution: stepped slopes and piedmont benchlands, lithogenic forms - terraces and passages, flattened summits and rounded hills. Using different types of the function f (block rise, swell, tilt), we obtained interesting reformations of initial tectonic landforms during the concurrent action of denudation processes. The result of such action differs from that of the successive action of tectonic movements and denudation. The relation of rates of the endogenous and exogenous processes strongly affects the formation of local morphostructures. Preservation of initial features of slope such as steps or bends as well as their formation due to tectonics or lithology is possible if coefficients B and Care small in comparison toA.

The Labdane Ent-3-Acetoxy-Labda-8(17), 13-Dien-15-Oic Decreases Blood Pressure In Hypertensive Rats

PubMed Central

Simplicio, Janaina A.; Simão, Marilia R.; Ambrosio, Sergio R.; Tirapelli, Carlos R.

2016-01-01

Background Labdane-type diterpenes induce lower blood pressure via relaxation of vascular smooth muscle; however, there are no studies describing the effects of labdanes in hypertensive rats. Objective The present study was designed to investigate the cardiovascular actions of the labdane-type diterpene ent-3-acetoxy-labda-8(17), 13-dien-15-oic acid (labda-15-oic acid) in two-kidney 1 clip (2K-1C) renal hypertension. Methods Vascular reactivity experiments were performed in aortic rings isolated from 2K-1C and normotensive (2K) male Wistar rats. Nitrate/nitrite (NOx) measurement was performed in aortas by colorimetric assay. Blood pressure measurements were performed in conscious rats. Results Labda-15-oic acid (0.1-300 µmol/l) and forskolin (0.1 nmol/l - 1 µmol/l) relaxed endothelium-intact and endothelium-denuded aortas from both 2K-1C and 2K rats. Labda-15-oic acid was more effective at inducing relaxation in endothelium-intact aortas from 2K pre-contracted with phenylephrine when compared to the endothelium-denuded ones. Forskolin was more potent than labda-15-oic acid at inducing vascular relaxation in arteries from both 2K and 2K-1C rats. Labda-15-oic acid-induced increase in NOx levels was lower in arteries from 2K-1C rats when compared to 2K rats. Intravenous administration of labda-15-oic acid (0.3-3 mg/kg) or forskolin (0.1-1 mg/kg) induced hypotension in conscious 2K-1C and 2K rats. Conclusion The present findings show that labda-15-oic acid induces vascular relaxation and hypotension in hypertensive rats. PMID:27096521

Relationship of compartment-specific structural knee status at baseline with change in cartilage morphology: a prospective observational study using data from the osteoarthritis initiative

PubMed Central

Eckstein, Felix; Wirth, Wolfgang; Hudelmaier, Martin I; Maschek, Susanne; Hitzl, Wolfgang; Wyman, Bradley T; Nevitt, Michael; Hellio Le Graverand, Marie-Pierre; Hunter, David

2009-01-01

Introduction The aim was to investigate the relationship of cartilage loss (change in medial femorotibial cartilage thickness measured with magnetic resonance imaging (MRI)) with compartment-specific baseline radiographic findings and MRI cartilage morphometry features, and to identify which baseline features can be used for stratification of fast progressors. Methods An age and gender stratified subsample of the osteoarthritis (OA) initiative progression subcohort (79 women; 77 men; age 60.9 ± 9.9 years; body mass index (BMI) 30.3 ± 4.7) with symptomatic, radiographic OA in at least one knee was studied. Baseline fixed flexion radiographs were read centrally and adjudicated, and cartilage morphometry was performed at baseline and at one year follow-up from coronal FLASH 3 Tesla MR images of the right knee. Results Osteophyte status at baseline was not associated with medial cartilage loss. Knees with medial joint space narrowing tended to show higher rates of change than those without, but the relationship was not statistically significant. Knees with medial femoral subchondral bone sclerosis (radiography), medial denuded subchondral bone areas (MRI), and low cartilage thickness (MRI) at baseline displayed significantly higher cartilage loss than those without, both with and without adjusting for age, sex, and BMI. Participants with denuded subchondral bone showed a standardized response mean of up to -0.64 versus -0.33 for the entire subcohort. Conclusions The results indicate that radiographic and MRI cartilage morphometry features suggestive of advanced disease appear to be associated with greater cartilage loss. These features may be suited for selecting patients with a higher likelihood of fast progression in studies that attempt to demonstrate the cartilage-preserving effect of disease-modifying osteoarthritis drugs. PMID:19534783