Sample records for aeolian ridges tars

  1. Morphology of transverse aeolian ridges (TARs) on Mars from a large sample: Further evidence of a megaripple origin?

    NASA Astrophysics Data System (ADS)

    Hugenholtz, Chris H.; Barchyn, Thomas E.; Boulding, Adam

    2017-04-01

    Using HiRISE digital terrain models (DTMs), we developed a large morphological dataset to examine the three-dimensional shape, size, and scaling of Martian transverse aeolian ridges (TARs). Considerable debate exists on the characteristic morphology of TARs and the origins of these enigmatic bedforms. Some researchers suggest polygenesis or multiple classes of similar bedforms. Reliably characterizing the morphology of TARs is an essential prerequisite to developing and evaluating process-based models of TAR genesis and unraveling aeolian processes on the surface of Mars. We present measurements of TAR morphology from a large, DTM-derived dataset (n = 2295). We focused on TARs with 'simple' morphologies in order enable more defensible discretization. Histograms and cumulative log-frequency plots of morphometric parameters (length, width, height, elongation ratio, and wavelength) indicate the sample represents a continuum of bedforms from a single population. A typical TAR from our dataset is 88.5 m long (longest planview axis), 17.3 m wide (shortest planview axis), 1.3 m tall, and has a wavelength of 25.8 m. Combined with these data, the bulk of evidence presented to date suggests that interpreting TARs as megaripples is the most viable working hypothesis.

  2. Transverse Aeolian Ridges on Mars: Sediment sources, volumes, and ages.

    NASA Astrophysics Data System (ADS)

    Berman, D. C.; Balme, M. R.

    2014-12-01

    Transverse Aeolian Ridges (TARs) are aeolian bedforms that are morphologically and dimensionally distinct from Large Dark Dune (LDD) fields, being generally brighter than, or of similar albedo to, the surrounding terrain. These features are significantly smaller than the LDDs, appear to form normal to local winds, and tend to have simple, transverse, ripple-like morphologies. Whether these small martian bedforms represent large granule ripples, small transverse dunes, or something else entirely is currently under debate. The spatial distribution of TARs provides important information about where on Mars aeolian sediments are concentrated, and determining their volume can help us constrain the sediment transport regime on Mars. Also, if we can determine if TARs were active only in the past, or whether TARs are mobile under today's wind conditions, then we can begin to assess when and where TARs are/were active over Mars' recent geological history. Thus TARs have the potential for being indicators/records of climate change on Mars. In this work we build on previous work [1,2] and focus on the local/regional scale. We have identified six regional study areas, each 5° by 5°, to investigate the behavior of TARs in detail; one in the northern hemisphere, three in the equatorial band, and two in the southern hemisphere. We have systematically mapped TAR and LDD deposits in each study area to constrain sediment transport pathways and identify sediment sources. In general, TAR sediments appear to be tied to local sources such as LDDs or layered terrains. HiRISE DTMs were utilized to measure TAR heights, widths, wavelengths, and lengths to calculate sediment volumes and estimate volumes over entire study areas based on mapping. Crater count analyses on contiguous TAR fields in the equatorial regions, where the bedforms appear more lithified, reveal ages of several million years. Mid-latitude TAR fields do not show any superposed craters, suggesting much younger deposits

  3. Transverse Aeolian Ridges (TARs) on Mars II: Distributions, orientations, and ages

    NASA Astrophysics Data System (ADS)

    Berman, Daniel C.; Balme, Matthew R.; Rafkin, Scot C. R.; Zimbelman, James R.

    2011-05-01

    Transverse Aeolian Ridges (TARs), 10 m scale, ripple-like aeolian bedforms with simple morphology, are widespread on Mars but it is unknown what role they play in Mars' wider sediment cycle. We present the results of a survey of all Mars Global Surveyor Narrow angle images in a pole-to-pole study area, 45° longitude wide. Following on from the classification scheme and preliminary surveys of Balme et al. (Balme, M.R., Berman, D.C., Bourke, M.C., Zimbelman, J.R. [2008a]. Geomorphology 101, 703-720) and Wilson and Zimbelman (Wilson, S.A., Zimbelman, J.R. [2004]. J. Geophys. Res. 109 (E10). doi: 10.1029/2004JE002247) we searched more than 10,000 images, and found that over 2000 reveal at least 5% areal cover by TARs. The mean TAR areal cover in the study area is about 7% (3% in the northern hemisphere and 11% in the southern hemisphere) but TARs are not homogenously distributed - they are concentrated in the mid-low latitudes and almost absent poleward of 35°N and 55°S. We found no clear correlation between TAR distribution and any of thermal inertia, kilometer-scale roughness, or elevation. We did find that TARs are less common at extremes of elevation. We found that TARs are most common near the equator (especially in the vicinity of Meridiani Planum, in which area they have a distinctive "barchan-like" morphology) and in large southern-hemisphere impact craters. TARs in the equatorial band are usually associated with outcrops of layered terrain or steep slopes, hence their relative absence in the northern hemisphere. TARs in the southern hemisphere are most commonly associated with low albedo, intercrater dune fields. We speculate that the mid-latitude mantling terrain (e.g., Mustard, J.F., Cooper, C.D., Rifkin, M.K. [2001]. Nature 412, 411-414; Kreslavsky, M.A., Head, J.W. [2002]. J. Geophys. Res. 29 (15). doi: 10.1029/2002GL015392) could also play a role in covering TARs or inhibiting saltation. We compared TAR distribution with general circulation model (GCM

  4. The birth and death of transverse aeolian ridges on Mars

    USGS Publications Warehouse

    Geissler, Paul E.

    2014-01-01

    Transverse aeolian ridges (TARs) are small bright windblown deposits found throughout the Martian tropics that stand a few meters tall and are spaced a few tens of meters apart. The origin of these features remains mysterious more than 20 years after their discovery on Mars. This paper presents a new hypothesis, that some of the TARs could be indurated dust deposits emplaced millions of years ago during periods of higher axial obliquity. It suggests that these TARs are primary depositional bed forms that accumulated in place from dust carried by the winds in suspension, perhaps in a manner comparable to antidunes on Earth, and were subsequently indurated and eroded to their current states by eons of sandblasting. It points out examples of modern dust drifts and dune-like features that appear to have been recently formed by dust accumulating directly onto the surface from atmospheric suspension. It shows how these pristine dust deposits could evolve to explain the range of morphologies of the TARs. Finally, it explains how the known properties of many TARs are consistent with this hypothesis, including their composition, thermal behavior, and distribution.

  5. The morphology of transverse aeolian ridges on Mars

    NASA Astrophysics Data System (ADS)

    Geissler, Paul E.; Wilgus, Justin T.

    2017-06-01

    A preliminary survey of publicly released high resolution digital terrain models (DTMs) produced by the High Resolution Imaging Science Experiment (HiRISE) camera on Mars Reconnaissance Orbiter identified transverse aeolian ridges (TARs) in 154 DTMs in latitudes from 50°S to 40°N. Consistent with previous surveys, the TARs identified in HiRISE DTMs are found at all elevations, irrespective of the regional thermal inertia of the surface. Ten DTMs were selected for measuring the characteristics of the TARs, including maximum height, mean height, mean spacing (wavelength), and the slope of the surface where they are located. We confined our measurements to features that were taller than 1 m and spaced more than 10 m apart. We found a surprisingly wide variability of TAR sizes within each local region (typically 5 km by 25 km), with up to a factor of 7 difference in TAR wavelengths in a single DTM. The TAR wavelengths do not appear to be correlated to latitude or elevation, but the largest TARs in our small survey were found at lower elevations. The tallest TARs we measured were on the flat floor of Moni crater, within Kaiser crater in the southern highlands. These TARs are up to 14 m tall, with a typical wavelength of 120 m. TAR heights are weakly correlated with their wavelengths. The height-to-wavelength ratios for most TARs are far less than 1/2π (the maximum predicted for antidunes), however in two cases the ratio is close to 1/2π, and in one case (in the bend of a channel) the ratio exceeds 1/2π. TAR wavelengths are uncorrelated with surface slope, both on local and regional scales. TAR heights are weakly anti-correlated with local slope. These results help constrain models of TAR formation, particularly a new hypothesis (Geissler, 2014) that suggests that TARs were formed from micron-sized dust that was transported in suspension. The lack of correlation between TAR wavelength and surface slope seems to rule out formation by gravity-driven dust flows such as

  6. Banded TARs in Iapygia

    NASA Image and Video Library

    2014-09-10

    The tropics of Mars are commonly littered with small bright ripples that were somehow shaped by the wind. NASA Mars Reconnaissance Orbiter might provide a valuable clue to the formation of transverse aeolian ridges TARs elsewhere on Mars.

  7. Building of tropical beach ridges, northeastern Queensland, Australia: Cyclone inundation and aeolian decoration

    NASA Astrophysics Data System (ADS)

    Tamura, Toru; Nicholas, William; Brooke, Brendan; Oliver, Thomas

    2016-04-01

    Processes associated with tropical cyclones are thought responsible for building coarse sand beach ridges along the northeastern Queensland coast, Australia. While these ridges are expected to be geological records of the past cyclone, they question the general consensus of the aeolian genesis of sandy beach ridges. To explore the ridge-forming process, we carried out the GPR survey, auger drilling, pit excavation, grain-size analysis, and OSL dating for coarse sand beach ridges at the Cowley Beach, northeastern Queensland. The Cowley Beach is a mesotidal beach characterized by a low-tide terrace and steep beach face. Ten beach ridges are recognized along the survey transect that extends 700 m inland from the shore. 37 OSL ages are younger seawards, indicating the seaward accretion of the ridge sequence over the last 2700 years. The highest ridge is +5.1 m high above AHD (Australian Height Datum). Two GPR units are bounded by a groundwater surface at c. +1.5 m AHD. The upper unit is characterized by horizontal to hummocky reflectors punctuated by seaward dipping truncation surfaces. These reflectors in places form dome-like structure that appears to be the nucleus of a beach ridge. The shape and level (+2.5 m AHD) of the dome are similar to those of the present swash berm. The lower unit shows a sequence of reflectors that dip at an angle of present beach face. The sequence is dissected by truncation surfaces, some of which are continuous to those in the upper unit. Coarse sand mainly forms beach ridge deposits below +4.0 m AHD, while a few higher ridges have an upward fining layer composed of medium sand above +4.0 m, which is finer than aeolian ripples found on the backshore during the survey. In addition, pumice gravel horizons underlie the examined ridge crests. The sequence of seaward dipping reflectors indicates that the Cowley Beach, like other many sandy beaches, has prograded during onshore sand accretion by fairweather waves and has been eroded by storms

  8. Surface-based 3D measurements of small aeolian bedforms on Mars and implications for estimating ExoMars rover traversability hazards

    NASA Astrophysics Data System (ADS)

    Balme, Matt; Robson, Ellen; Barnes, Rob; Butcher, Frances; Fawdon, Peter; Huber, Ben; Ortner, Thomas; Paar, Gerhard; Traxler, Christoph; Bridges, John; Gupta, Sanjeev; Vago, Jorge L.

    2018-04-01

    Recent aeolian bedforms comprising loose sand are common on the martian surface and provide a mobility hazard to Mars rovers. The ExoMars rover will launch in 2020 to one of two candidate sites: Mawrth Vallis or Oxia Planum. Both sites contain numerous aeolian bedforms with simple ripple-like morphologies. The larger examples are 'Transverse Aeolian Ridges' (TARs), which stereo imaging analyses have shown to be a few metres high and up to a few tens of metres across. Where they occur, TARs therefore present a serious, but recognized and avoidable, rover mobility hazard. There also exists a population of smaller bedforms of similar morphology, but it is unknown whether these bedforms will be traversable by the ExoMars rover. We informally refer to these bedforms as "mini-TARs", as they are about an order of magnitude smaller than most TARs observed to date. They are more abundant than TARs in the Oxia Planum site, and can be pervasive in areas. The aim of this paper is to estimate the heights of these features, which are too small to measured using High Resolution Imaging Science Experiment (HiRISE) Digital Elevation Models (DEMs), from orbital data alone. Thereby, we aim to increase our knowledge of the hazards in the proposed ExoMars landing sites. We propose a methodology to infer the height of these mini-TARs based on comparisons with similar features observed by previous Mars rovers. We use rover-based stereo imaging from the NASA Mars Exploration Rover (MER) Opportunity and PRo3D software, a 3D visualisation and analysis tool, to measure the size and height of mini-TARs in the Meridiani Planum region of Mars. These are good analogues for the smaller bedforms at the ExoMars rover candidate landing sites. We show that bedform height scales linearly with length (as measured across the bedform, perpendicular to the crest ridge) with a ratio of about 1:15. We also measured the lengths of many of the smaller aeolian bedforms in the ExoMars rover Oxia Planum

  9. Surface-Based 3d measurements of aeolian bedforms on Mars

    NASA Astrophysics Data System (ADS)

    Balme, Matthew; Robson, Ellen; Barnes, Robert; Huber, Ben; Butcher, Frances; Fawdon, Peter; Gupta, Sanjeev; Paar, Gerhard

    2017-04-01

    The surface of Mars hosts many different types of aeolian bedforms, from small wind-ripples with cm-scale wavelength, through decametre-scale "Transverse Aeolian Ridges" (TARs), to km-scale dunes. To date, all mobile Mars surface-missions ('Rovers') have encountered aeolian bedforms of one kind or another. Aeolian deposits of loose, unconsolidated material provide hazards to Mars Rovers: sinkage into the aeolian material and enhanced slippage can prevent traction and forward progress, forcing the Rover to backtrack (e.g., MER Opportunity) and can even 'trap' the rover ending the mission (e.g., MER Spirit). Here, we present morphometry measurements of meter-scale ripple-like bedforms on Mars, as observed by the MER Opportunity Rover during its traverse across the Meridiani Planum region of Mars. The aim is to assess whether there is a relationship between bedforms parameters that can be measured from orbit such as length and width, and bedform height, which can only be reliably measured from orbit for larger features such as TARs. If such a relationship can be found, it might allow estimates of ripple-height to be made from remote sensing data alone. This could help understand the formation mechanism and provide a better characterization of the hazard presented by these features. For much of the first 30 km of the traverse, Opportunity travelled across flat plains with meter-scale, ripple-like aeolian bedforms ("plains ripples") superposed upon them. During the traverse, the Rover acquired stereo imaging data of its surroundings using both its scientific Pancam cameras system and the navigational Navcam system. Using these data, and newly developed Pro3D™ and PRoViP™ software from Joanneum Research, we obtained Digital Elevation Models of many areas along the traverse, allowing us to measure the heights, widths and lengths of aeolian bedforms. In addition, the same bedforms were digitized from orbital HiRISE image data (25 cm/pix resolution) in ArcGIS software

  10. The Variability of Transverse Aeolian Ripples in Troughs on Mars

    NASA Technical Reports Server (NTRS)

    Bourke, M. C.; Wilson, S.A.; Zimbelman, J. R.

    2003-01-01

    A precursory glance at MGS images of the surface of Mars show an abundance of aeolian transverse ridges. These ridges are located in a variety of geological terrains. Zimbelman and Wilson have separated the small-scale aeolian features of Syrtis Major into six categories: ripples associated with obstacles, ripple bands, ripple fields, ripple patches, isolated ripple patches and ripples associated with dunes. This paper focuses on one of these categories, that of ripple bands which tend to accumulate within linear troughs. As the origin of these features is still being studied (i.e. ripples versus dunes), we refer to them simply as transverse aeolian ridges.

  11. Aviation Turbine Fuels from Tar Sands Bitumen and Heavy Oils. Part 1. Process Analysis.

    DTIC Science & Technology

    1984-09-01

    Uinta Basin .......................too.... 11 b . Asphalt Ridge ........................ 13 c.* Tar Sand Triangle ..... to .. .. . .. .. . 15 e...Estimated ............**..* 7 3 CHARACTERISTICS OF UTAH’S MAJOR TAR SANDS ....... 12 4 UINTA BASIN DEPOSITS ................... *........ 13 *.5 UINTA ...7 UINTA BASIN , UTAH PROPERTIES -SUNNYSIDE ........ 20 8 UINTA BASIN , UTAH PROPERTIES -P. R. SPRINGS . 22 r9 ESTIMATED CALIFORNIA TAR SAND DISTRIBUTION

  12. Gone But Not Forgotten: The Aeolian Modification of Fluvial Surfaces on Mars: Preliminary Results from Central Australia

    NASA Technical Reports Server (NTRS)

    Bourke, M. C.

    2003-01-01

    MOC images indicate that aeolian ridges may mask and even obliterate primary depositional surfaces on Mars. This modification increases the difficulty in mapping the recent geological history of the planet. An analogue study in central Australia demonstrates how patterns in aeolian dunes, formed over abandoned fluvial surfaces, can be used to detect buried fluvial features.

  13. Terrestrial sensitivity to abrupt cooling recorded by aeolian activity in northwest Ohio, USA

    USGS Publications Warehouse

    Campbell, M.C.; Fisher, T.G.; Goble, R.J.

    2011-01-01

    Optically stimulated luminescence dated sand dunes and Pleistocene beach ridges in northwest Ohio are used to reconstruct landscape modification more than 5000. yr after deglaciation. Four of the OSL ages (13.3-11.1. ka) cluster around the Younger Dryas cold event, five ages (10.8-8.2. ka) cluster around the Preboreal, one young age (0.9-0.7. ka) records more recent aeolian activity, and one age of 15.1-13.1. ka dates a barrier spit in Lake Warren. In northwest Ohio, both landscape instability recorded by aeolian activity and a vegetation response recorded by pollen are coeval with the Younger Dryas. However, the climate conditions during the Preboreal resulting in aeolian activity are not recorded in the available pollen records. From this, we conclude that aeolian dunes and surfaces susceptible to deflation are sensitive to cooler, drier episodes of climate and can complement pollen data. Younger Dryas and Preboreal aged aeolian activity in northwestern Ohio coincides with aeolian records elsewhere in the Great Lakes region east of the prairie-forest ecotone. ?? 2011 University of Washington.

  14. The potential use of tar sand bitumen as paving asphalt

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

    Petersen, J.C.

    1988-01-01

    In this paper several research reports describing the preparation of potential paving asphalts from tar sand bitumen are reviewed and the results of the studies compared. The tar sand asphalts described in the studies were prepared from 1) hot water-recovered bitumen from deposits near San Luis Obispo, California (Edna deposits), and deposits near Vernal and Sunnyside, Utah; and 2) bitumen recovered from the Northwest Asphalt Ridge deposits near Vernal, Utah, by both in situ steamflood and in situ combustion recovery processes. Important properties of the tar sand asphalts compare favorably with those of specification petroleum asphalts. Laboratory data suggest thatmore » some tar sand asphalts may have superior aging characteristics and produce more water-resistant paving mixtures than typical petroleum asphalts.« less

  15. Aeolian Sediment Transport Pathways and Aerodynamics at Troughs on Mars

    NASA Technical Reports Server (NTRS)

    Bourke, Mary C.; Bullard, Joanna E.; Barnouin-Jha, Olivier S.

    2004-01-01

    Interaction between wind regimes and topography can give rise to complex suites of aeolian landforms. This paper considers aeolian sediment associated wit11 troughs on Mars and identifies a wider range of deposit types than has previously been documented. These include wind streaks, falling dunes, "lateral" dunes, barchan dunes, linear dunes, transverse ridges, sand ramps, climbing dunes, sand streamers, and sand patches. The sediment incorporated into these deposits is supplied by wind streaks and ambient Planitia sources as well as originating within the trough itself, notably from the trough walls and floor. There is also transmission of sediment between dneTsh. e flow dynamics which account for the distribution of aeolian sediment have been modeled using two-dimensional computational fluid dynamics. The model predicts flow separation on the upwind side of the trough followed by reattachment and acceleration at the downwind margin. The inferred patterns of sediment transport compare well with the distribution of aeolian forms. Model data indicate an increase of wind velocity by approx. 30 % at the downwind trough margin. This suggests that the threshold wind speed necessary for sand mobilization on Mars will be more freqentmlye t in these inclined locations.

  16. River of Sand

    NASA Image and Video Library

    2016-09-21

    A dominant driver of surface processes on Mars today is aeolian (wind) activity. In many cases, sediment from this activity is trapped in low-lying areas, such as craters. Aeolian features in the form of dunes and ripples can occur in many places on Mars depending upon regional wind regimes. The Cerberus Fossae are a series of discontinuous fissures along dusty plains in the southeastern region of Elysium Planitia. This rift zone is thought to be the result of combined volcano-tectonic processes. Dark sediment has accumulated in areas along the floor of these fissures as well as inactive ripple-like aeolian bedforms known as "transverse aeolian ridges" (TAR). Viewed through HiRISE infrared color, the basaltic sand lining the fissures' floor stands out as deep blue against the light-toned dust covering the region. This, along with the linearity of the fissures and the wave-like appearance of the TAR, give the viewer an impression of a river cutting through the Martian plains. However, this river of sand does not appear to be flowing. Analyses of annual monitoring images of this region have not detected aeolian activity in the form of ripple migration thus far. http://photojournal.jpl.nasa.gov/catalog/PIA21063

  17. Aeolian sand transport and aeolian deposits on Venus: A review

    NASA Astrophysics Data System (ADS)

    Kreslavsly, Mikhail A.; Bondarenko, Nataliya V.

    2017-06-01

    We review the current state of knowledge about aeolian sand transport and aeolian bedforms on planet Venus. This knowledge is limited by lack of observational data. Among the four planetary bodies of the Solar System with sufficient atmospheres in contact with solid surfaces, Venus has the densest atmosphere; the conditions there are transitional between those for terrestrial subaerial and subaqueous transport. The dense atmosphere causes low saltation threshold and short characteristic saltation length, and short scale length of the incipient dunes. A few lines of evidence indicate that the typical wind speeds exceed the saltation threshold; therefore, sand transport would be pervasive, if sand capable of saltation is available. Sand production on Venus is probably much slower than on the Earth; the major terrestrial sand sinks are also absent, however, lithification of sand through sintering is expected to be effective under Venus' conditions. Active transport is not detectable with the data available. Aeolian bedforms (transverse dunes) resolved in the currently available radar images occupy a tiny area on the planet; however, indirect observations suggest that small-scale unresolved aeolian bedforms are ubiquitous. Aeolian transport is probably limited by sand lithification causing shortage of saltation-capable material. Large impact events likely cause regional short-term spikes in aeolian transport by supplying a large amount of sand-size particles, as well as disintegration and activation of older indurated sand deposits. The data available are insufficient to understand whether the global aeolian sand transport occurs or not. More robust knowledge about aeolian transport on Venus is essential for future scientific exploration of the planet, in particular, for implementation and interpretation of geochemical studies of surface materials. High-resolution orbital radar imaging with local to regional coverage and desirable interferometric capabilities is the

  18. Ripples and Dunes in Proctor Crater

    NASA Image and Video Library

    2017-10-09

    NASA's Mars Reconnaissance Rover (MRO) has observed two types of wind (aeolian) features in Proctor Crater: large, dark features that are sand dunes, made up of basaltic particles, and smaller, light-toned ripples that we call "TAR," or "transverse aeolian ridges." The origin of the TARs is a mystery. They might be dust deposits, or perhaps coarse grained ripples that are coated in bright dust. These TARs are less than 10 meters tall, and are much smaller than the sand dunes that reach impressive heights of over 130 meters. In other places on Mars, TARs are generally older than sand dunes, but here in Proctor Crater, it is not so obvious. How can we tell which came first, the TARs or the dunes? The dunes are situated on top of the TARs, and with this information, we can say the dunes are clearly the younger formations here in Proctor Crater. Fortunately, HiRISE has a tool that can solve this riddle. By taking stereo images of the same region from two different locations, we can estimate the topography of the region by measuring the displacement of surface features from one picture to the other. The result is a quantitative estimate of the local surface topography, called a digital terrain model. The dunes are situated on top of the TARs, and with this information, we can say the dunes are clearly the younger formations here in Proctor Crater. https://photojournal.jpl.nasa.gov/catalog/PIA22040

  19. Coal Tar and Coal-Tar Pitch

    Cancer.gov

    Learn about coal-tar products, which can raise your risk of skin cancer, lung cancer, and other types of cancer. Examples of coal-tar products include creosote, coal-tar pitch, and certain preparations used to treat skin conditions such as eczema, psoriasis, and dandruff.

  20. Erosion and Deposition in Schaeberle Crater

    NASA Image and Video Library

    2016-01-14

    Schaeberle Crater is a large, heavily-infilled crater with many interesting features. This image NASA Mars Reconnaissance Orbiter spacecraft shows a window into the crater fill deposit, showcasing eroding bedrock and aeolian landforms. This pit is located near the geometric center of our image, making it a central pit crater. Central pit craters are thought to form from impact melt draining through subsurface cracks in the deepest part of the crater shortly following impact. A closeup image shows light-toned bedrock and a small cliff that appears to be weathering away. Below the cliff there are several different types of aeolian features, including ripples and transverse aeolian ridges (TAR). The sand that forms the small, bluish ripples may be weathering out of the cliff face, in contrast to the larger, light-toned TAR which are thought to be currently inactive. More of the TAR are visible in another closeup image. In this case, they are clearly covered by a dark, ripple-covered sand sheet. We have only imaged this location once, so it is impossible to determine whether or not the sand sheet is blowing in the wind. But due to repeated HiRISE imaging in other areas, active dunes are now known to be common across Mars and we can reasonably speculate that these dunes are moving, too. http://photojournal.jpl.nasa.gov/catalog/PIA20339

  1. HIGH-ANGLE AEOLIAN CROSSBEDDING AT TRAIL RIDGE, FLORIDA.

    USGS Publications Warehouse

    Force, Eric; Garnar, Tom

    1985-01-01

    This paper described new evidence concerning the origin of the Trail Ridge mineral sands deposit in Florida. Rarely exposed sections of the orebody exhibit structures indicative of sand dune formation rather than coastal beach sand accumulation. The implications for mineral sands exploration, and therefore resources, in the southeastern USA are highlighted.

  2. Coal tar phototherapy for psoriasis reevaluated: erythemogenic versus suberythemogenic ultraviolet with a tar extract in oil and crude coal tar

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

    Lowe, N.J.; Wortzman, M.S.; Breeding, J.

    1983-06-01

    Recent studies have questioned the therapeutic value of coal tar versus ultraviolet (UV) radiation and their relative necessity in phototherapy for psoriasis. In this investigation, different aspects of tar phototherapy have been studied in single-blind bilateral paired comparison studies. The effects of 1% crude coal tar were compared with those of petrolatum in conjunction with erythemogenic and suberythemogenic doses of ultraviolet light (UVB) using a FS72 sunlamp tubed cabinet. Crude coal tar was clinically superior to petrolatum with suberythemogenic ultraviolet. With the erythemogenic UVB, petrolatum was equal in efficacy to crude coal tar. Suberythemogenic UVB was also used adjunctively tomore » compare the effects of a 5% concentration of a tar extract in an oil base to 5% crude coal tar in petrolatum or the oil base without tar. The tar extract in oil plus suberythemogenic UVB produced significantly more rapid improvement than the oil base plus UVB. The direct bilateral comparison of equal concentrations of tar extract in oil base versus crude coal tar in petrolatum in a suberythemogenic UV photo regimen revealed no statistical differences between treatments. In a study comparing tar extract in oil and the oil base without ultraviolet radiation, the tar extract in oil side responded more rapidly.« less

  3. Aeolian Processes and the Biosphere

    NASA Astrophysics Data System (ADS)

    Ravi, Sujith; D'Odorico, Paolo; Breshears, David D.; Field, Jason P.; Goudie, Andrew S.; Huxman, Travis E.; Li, Junran; Okin, Gregory S.; Swap, Robert J.; Thomas, Andrew D.; Van Pelt, Scott; Whicker, Jeffrey J.; Zobeck, Ted M.

    2011-08-01

    Aeolian processes affect the biosphere in a wide variety of contexts, including landform evolution, biogeochemical cycles, regional climate, human health, and desertification. Collectively, research on aeolian processes and the biosphere is developing rapidly in many diverse and specialized areas, but integration of these recent advances is needed to better address management issues and to set future research priorities. Here we review recent literature on aeolian processes and their interactions with the biosphere, focusing on (1) geography of dust emissions, (2) impacts, interactions, and feedbacks, (3) drivers of dust emissions, and (4) methodological approaches. Geographically, dust emissions are highly spatially variable but also provide connectivity at global scales between sources and effects, with “hot spots” being of particular concern. Recent research reveals that aeolian processes have impacts, interactions, and feedbacks at a variety of scales, including large-scale dust transport and global biogeochemical cycles, climate mediated interactions between atmospheric dust and ecosystems, impacts on human health, impacts on agriculture, and interactions between aeolian processes and dryland vegetation. Aeolian dust emissions are driven largely by, in addition to climate, a combination of soil properties, soil moisture, vegetation and roughness, biological and physical crusts, and disturbances. Aeolian research methods span laboratory and field techniques, modeling, and remote sensing. Together these integrated perspectives on aeolian processes and the biosphere provide insights into management options and aid in identifying research priorities, both of which are increasingly important given that global climate models predict an increase in aridity in many dryland systems of the world.

  4. Down in the Paleochannels

    NASA Image and Video Library

    2015-11-27

    This whole area, located in Solis Planum, is an interesting, tectonic terrain south of Noctis Labrynthus which generally slopes toward the south as seen by NASA Mars Reconnaissance Orbiter spacecraft. Transverse aeolian ridges -- or TAR -- are mysterious, wind-blown features that are intermediate in size between ripples and much larger sand dunes. Ripples form from hopping sand grains, and dunes form from sand grains being blown over longer distances. One hypothesis for TAR formation is that larger grains like pebbles are rolled on top of smaller ripples; then, finer dust settles into the cracks, "inflating" the pebbles, making the TAR larger than typical ripples. Looking between the TAR, one sees a network of ancient, beaten-up channels that were carved by water, lava, or both. This whole area is located in Solis Planum, an interesting, tectonic terrain south of Noctis Labrynthus which generally slopes toward the south. http://photojournal.jpl.nasa.gov/catalog/PIA20157

  5. High-Altitude Aeolian Research on the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Dong, Zhibao; Hu, Guangyin; Qian, Guangqiang; Lu, Junfeng; Zhang, Zhengcai; Luo, Wanyin; Lyu, Ping

    2017-12-01

    Aeolian processes and their role in desertification have been studied extensively at low elevations but have been rarely studied at high elevations in areas such as the Tibetan Plateau, where aeolian processes were active in the geologic past and remain active today. In this review, we summarize research that improves our understanding of aeolian processes on the Tibetan Plateau, including the distribution, characteristics, and provenance of aeolian sediments; the history of aeolian activity; aeolian geomorphology; and wind-driven land degradation. Contemporary aeolian processes primarily occur in dry basins, in wide river valleys, on lakeshores, on mountain slopes, and on gravel pavements. Sediment characteristics suggest a local origin and provide interesting contrasts with those of China's Loess Plateau. The history of aeolian activity and its paleoclimatic implications, reconstructed based on aeolian archives, is short (mostly since the Late Glacial) and shows wide regional differences. Aeolian geomorphology is simple and suggests short formation time. Wind-driven land degradation is less severe than previously thought, driven by different factors in different areas, and exhibited complex interactions with freeze-thaw processes. Aeolian research has been conducted within the general framework of aeolian science but addresses issues specific to the Tibetan Plateau that arise due to the low air temperature, low air density, and the presence of a cryosphere. We propose six priorities for future research: aeolian physics, the effect of freeze-thaw cycles, comparisons with other areas, regional differences, effects of wind-driven land degradation, and integrated observation and monitoring.

  6. The aeolian wind tunnel

    NASA Technical Reports Server (NTRS)

    Iversen, J. D.

    1991-01-01

    The aeolian wind tunnel is a special case of a larger subset of the wind tunnel family which is designed to simulate the atmospheric surface layer winds to small scale (a member of this larger subset is usually called an atmospheric boundary layer wind tunnel or environmental wind tunnel). The atmospheric boundary layer wind tunnel is designed to simulate, as closely as possible, the mean velocity and turbulence that occur naturally in the atmospheric boundary layer (defined as the lowest portion of the atmosphere, of the order of 500 m, in which the winds are most greatly affected by surface roughness and topography). The aeolian wind tunnel is used for two purposes: to simulate the physics of the saltation process and to model at small scale the erosional and depositional processes associated with topographic surface features. For purposes of studying aeolian effects on the surface of Mars and Venus as well as on Earth, the aeolian wind tunnel continues to prove to be a useful tool for estimating wind speeds necessary to move small particles on the three planets as well as to determine the effects of topography on the evolution of aeolian features such as wind streaks and dune patterns.

  7. Multi-Resolution Analysis of LiDAR data for Characterizing a Stabilized Aeolian Landscape in South Texas

    NASA Astrophysics Data System (ADS)

    Barrineau, C. P.; Dobreva, I. D.; Bishop, M. P.; Houser, C.

    2014-12-01

    Aeolian systems are ideal natural laboratories for examining self-organization in patterned landscapes, as certain wind regimes generate certain morphologies. Topographic information and scale dependent analysis offer the opportunity to study such systems and characterize process-form relationships. A statistically based methodology for differentiating aeolian features would enable the quantitative association of certain surface characteristics with certain morphodynamic regimes. We conducted a multi-resolution analysis of LiDAR elevation data to assess scale-dependent morphometric variations in an aeolian landscape in South Texas. For each pixel, mean elevation values are calculated along concentric circles moving outward at 100-meter intervals (i.e. 500 m, 600 m, 700 m from pixel). The calculated average elevation values plotted against distance from the pixel of interest as curves are used to differentiate multi-scalar variations in elevation across the landscape. In this case, it is hypothesized these curves may be used to quantitatively differentiate certain morphometries from others like a spectral signature may be used to classify paved surfaces from natural vegetation, for example. After generating multi-resolution curves for all the pixels in a selected area of interest (AOI), a Principal Components Analysis is used to highlight commonalities and singularities between generated curves from pixels across the AOI. Our findings suggest that the resulting components could be used for identification of discrete aeolian features like open sands, trailing ridges and active dune crests, and, in particular, zones of deflation. This new approach to landscape characterization not only works to mitigate bias introduced when researchers must select training pixels for morphometric investigations, but can also reveal patterning in aeolian landscapes that would not be as obvious without quantitative characterization.

  8. Tar sand extraction by steam stimulation and steam drive: measurement of physical properties

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

    Linberg, W.R.

    The measurement of the following thermophysical properties of Utah tar sands is in progress: thermal conductivity, specific heat relative permeability, and viscosity (of the recovered bitumen). During the report period (October 1, 1978 to November 1, 1979), experimental procedures have been developed and a basic data set has been measured. Additionally, standard core analysis has been performed for four drill sites in the Asphalt Ridge, Utah area.

  9. The Usumacinta-Grijalva beach-ridge plain in southern Mexico: a high-resolution archive of river discharge and precipitation

    NASA Astrophysics Data System (ADS)

    Nooren, Kees; Hoek, Wim Z.; Winkels, Tim; Huizinga, Annika; Van der Plicht, Hans; Van Dam, Remke L.; Van Heteren, Sytze; Van Bergen, Manfred J.; Prins, Maarten A.; Reimann, Tony; Wallinga, Jakob; Cohen, Kim M.; Minderhoud, Philip; Middelkoop, Hans

    2017-09-01

    The beach-ridge sequence of the Usumacinta-Grijalva delta borders a 300 km long section of the southern Gulf of Mexico coast. With around 500 beach ridges formed in the last 6500 years, the sequence is unsurpassed in the world in terms of numbers of individual ridges preserved, continuity of the record, and temporal resolution. We mapped and dated the most extensively accreted part of the sequence, linking six phases of accretion to river mouth reconfigurations and constraining their ages with 14C and OSL dating. The geomorphological and sedimentological reconstruction relied on lidar data, coring transects, GPR measurements, grain-size analyses, and chemical fingerprinting of volcanic glass and pumice encountered within the beach and dune deposits. We demonstrate that the beach-ridge complex was formed under ample long-term fluvial sediment supply and shorter-term wave- and aeolian-modulated sediment reworking. The abundance of fluvially supplied sand is explained by the presence of easily weatherable Los Chocoyos ignimbrites from the ca. 84 ka eruption of the Atitlán volcano (Guatemala) in the catchment of the Usumacinta River. Autocyclic processes seem responsible for the formation of ridge-swale couplets. Fluctuations in their periodicity (ranging from 6-19 years) are governed by progradation rate, and are therefore not indicative of sea level fluctuations or variability in storm activity. The fine sandy beach ridges are mainly swash built. Ridge elevation, however, is strongly influenced by aeolian accretion during the time the ridge is located next to the beach. Beach-ridge elevation is negatively correlated with progradation rate, which we relate to the variability in sediment supply to the coastal zone, reflecting decadal-scale precipitation changes within the river catchment. In the southern Mexican delta plain, the coastal beach ridges therefore appear to be excellent recorders of hinterland precipitation.

  10. Aeolian Sediments on the northeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Stauch, G.; Lehmkuhl, F.

    2013-12-01

    The timing and spatial distribution of aeolian sediments on the northeastern Tibetan Plateau have gained increasing interest during the last decades. The formation of the aeolian deposits is often related to cold and dry climate conditions. However, further important parameters are the local geomorphological setting and sediment availability in the source areas of the sediments. Aeolian sediments including loess, sandy loess and sands are widespread in the catchment of the Donggi Cona on the northeastern Tibetan Plateau at around 4000 m asl. Detailed geomorphological mapping of the deposits and geochemical analyses of the sediments revealed varying sources throughout the Holocene. The timing of the sediment deposition is based on 43 OSL (optical stimulated luminescence) ages. Several phases of enhanced aeolian deposition took place during the Holocene. The accumulation of aeolian sands lasted from 10.5 until 7 ka. The main source area of these sands was a large alluvial fan. Parallel to the formation of the dunes loess was deposited on the adjacent slopes from 10.5 until 7.5 ka. These sediments most probably originate in the nearby Qaidam Basin. In contrast to the general linkage of aeolian sediments to dryer climate conditions formation of these aeolian deposits is related to wetter conditions due to a strengthening of the Asian Summer Monsoons. The wetter climate enhanced the trapping and continuous fixation of the aeolian sediments by vegetation. With the further strengthening of the Monsoon fluvial processes eroded the aeolian deposits at least until 6 ka. From about 3 ka to the present a reactivation of aeolian sands and the formation of new dunes took place. This reactivation is related to drier conditions on the north-eastern Tibetan Plateau. Additionally, an increased human influence might have enhanced the aeolian activity. Similar phases of enhanced aeolian activity have been documented in more than 170 available OSL ages from loess and aeolian sands in

  11. Ground robotic measurement of aeolian processes

    NASA Astrophysics Data System (ADS)

    Qian, Feifei; Jerolmack, Douglas; Lancaster, Nicholas; Nikolich, George; Reverdy, Paul; Roberts, Sonia; Shipley, Thomas; Van Pelt, R. Scott; Zobeck, Ted M.; Koditschek, Daniel E.

    2017-08-01

    Models of aeolian processes rely on accurate measurements of the rates of sediment transport by wind, and careful evaluation of the environmental controls of these processes. Existing field approaches typically require intensive, event-based experiments involving dense arrays of instruments. These devices are often cumbersome and logistically difficult to set up and maintain, especially near steep or vegetated dune surfaces. Significant advances in instrumentation are needed to provide the datasets that are required to validate and improve mechanistic models of aeolian sediment transport. Recent advances in robotics show great promise for assisting and amplifying scientists' efforts to increase the spatial and temporal resolution of many environmental measurements governing sediment transport. The emergence of cheap, agile, human-scale robotic platforms endowed with increasingly sophisticated sensor and motor suites opens up the prospect of deploying programmable, reactive sensor payloads across complex terrain in the service of aeolian science. This paper surveys the need and assesses the opportunities and challenges for amassing novel, highly resolved spatiotemporal datasets for aeolian research using partially-automated ground mobility. We review the limitations of existing measurement approaches for aeolian processes, and discuss how they may be transformed by ground-based robotic platforms, using examples from our initial field experiments. We then review how the need to traverse challenging aeolian terrains and simultaneously make high-resolution measurements of critical variables requires enhanced robotic capability. Finally, we conclude with a look to the future, in which robotic platforms may operate with increasing autonomy in harsh conditions. Besides expanding the completeness of terrestrial datasets, bringing ground-based robots to the aeolian research community may lead to unexpected discoveries that generate new hypotheses to expand the science

  12. Comminution of Aeolian Materials on Mars

    NASA Technical Reports Server (NTRS)

    Marshall, John R.

    1998-01-01

    The research task had a two-year performance period for the investigation of aeolian processes on Mars. Specifically, we were investigating the comminution of sand grains as individual particles, and as bulk populations. Laboratory experiment were completed for the individual particles, and results led to new theory for aeolian transport that is broadly applicable to all planetary surfaces. The theory was presented at the LPSC and the GSA in 1998 and 1997 respectively. Essentially, the new theory postulates that aeolian transport is dependent upon two motion thresholds- an aerodynamic threshold and a bed-dilatancy threshold.

  13. Aeolian geomorphology from the global perspective

    NASA Technical Reports Server (NTRS)

    Greeley, R.

    1985-01-01

    Any planet or satellite having a dynamic atmosphere and a solid surface has the potential for experiencing aeolian (wind) processes. A survey of the Solar System shows at least four planetary objects which potentially meet these criteria: Earth, Mars, Venus, and possibly Titan, the largest satellite of Saturn. While the basic process is the same among these four objects, the movement of particles by the atmosphere, the aeolian environment is drastically different. It ranges from the hot (730 K), dense atmosphere of Venus to the extremely cold desert (218 K) environment of Mars where the atmospheric surface pressure is only approximately 7.5 mb. In considering aeolian processes in the planetary perspective, all three terrestrial planets share some common areas of attention for research, especially in regard to wind erosion and dust storms. Relevant properties of planetary objects potentially subject to aeolian processes are given in tabular form.

  14. Radar-aeolian roughness project

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Dobrovolskis, A.; Gaddis, L.; Iversen, J. D.; Lancaster, N.; Leach, Rodman N.; Rasnussen, K.; Saunders, S.; Vanzyl, J.; Wall, S.

    1991-01-01

    The objective is to establish an empirical relationship between measurements of radar, aeolian, and surface roughness on a variety of natural surfaces and to understand the underlying physical causes. This relationship will form the basis for developing a predictive equation to derive aeolian roughness from radar backscatter. Results are given from investigations carried out in 1989 on the principal elements of the project, with separate sections on field studies, radar data analysis, laboratory simulations, and development of theory for planetary applications.

  15. An NMR (Nuclear Magnetic Resonance) Investigation of the Chemical Association and Molecular Dynamics in Asphalt Ridge Tar Sand Ore and Bitumen

    DOE R&D Accomplishments Database

    Netzel, D. A.; Coover, P. T.

    1987-09-01

    Preliminary studies on tar sand bitumen given in this report have shown that the reassociation of tar sand bitumen to its original molecular configuration after thermal stressing is a first-order process requiring nearly a week to establish equilibrium. Studies were also conducted on the dissolution of tar sand bitumen in solvents of varying polarity. At a high-weight fraction of solute to solvent the apparent molecular weight of the bitumen molecules was greater than that of the original bitumen when dissolved in chloroform-d{sub 1} and benzene-d{sub 6}. This increase in the apparent molecular weight may be due to micellar formation or a weak solute-solvent molecular complex. Upon further dilution with any of the solvents studied, the apparent molecular weight of the tar sand bitumen decreased because of reduced van der Waals forces of interaction and/or hydrogen bonding. To define the exact nature of the interactions, it will be necessary to have viscosity measurements of the solutions.

  16. Low-tar and high-tar cigarettes

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

    Holt, P.G.; Chalmer, J.E.; Roberts, L.M.

    Mice were exposed for 7 to 8 minutes on weekdays to fresh smoke from high-tar (HT) or low-tar (LT) cigarettes for varying periods of up to 36 weeks. Mice exposed to HT cigarettes exhibited more marked alterations in humoral immune responsiveness, hematological profiles, and pulmonary pathologic findings than those exposed to LT cigarettes. However, cell-mediated immune responsiveness to both bacterial and tumor-specific antigens was depressed similarly in animals exposed to HT or LT cigarettes. Furthermore, the growth rates of subcutaneously established tumors were enhanced similarly in the two groups, with respect to those in control animals.

  17. Spatial differences of aeolian desertification responses to climate in arid Asia

    NASA Astrophysics Data System (ADS)

    Wang, Xunming; Hua, Ting; Lang, Lili; Ma, Wenyong

    2017-01-01

    Most areas of arid Asia are covered by aeolian dunes, sand sheets, gravels, and desert steppes, and may jeopardize nearly 350 million people if climate change increases aeolian desertification. Although the aeolian desertification is mainly triggered by climate changes are extensively acknowledged, the responses of aeolian desertification to various climate scenarios are poorly understood. Based on the tight combinations of dune activity index (DAI) trends and of aeolian desertification, here the spatial differences of aeolian desertification responses on various climate scenarios were reported. The analyzed results show that the variations in temperature, precipitation and wind regime have no significant contributions on aeolian desertification in the extremely arid Asia. From the early to blooming periods of vegetation growth, although temperature rise may benefit vegetation growths in some high latitudes and altitudes, the temperature rise may increase aeolian desertification in most arid Asia regions such as Mongolia, West and Central Asia. In arid Asia, although precipitation increases may benefit the rehabilitation, decreases in precipitation is not the key role on aeolian desertification occurrences in extremely arid regions. From the early to blooming periods of vegetation growths, spatial trends of the sensitivity of aeolian desertification to wind regime varied. Generally, at the regional scales there are relative high sensitivities for aeolian desertification to climate changes in the eastern and western regions of arid Asia, and the climate changes may not play important roles on aeolian desertification occurrence in the central regions. The spatial differences of aeolian desertification responses to climate changes indicate various strategies for aeolian desertification combating are needed in different regions of arid Asia.

  18. Aeolian Rat Tails (ARTs): A New Morphological Indicator of Abrasion Direction

    NASA Astrophysics Data System (ADS)

    Favaro, E. A.; Hugenholtz, C.; Barchyn, T.

    2016-12-01

    Aeolian rat tails (ARTs) are a previously undocumented aeolian abrasion feature observed on ignimbrite surfaces in the Puna Plateau of Northwest Argentina and bare morphological similarity to small-scale features on Mars. We describe the terrestrial features and present an evolutionary sequence from inception to demise. ARTs are regionally-ubiquitous and characterized by a windward abrasion-resistant lithic clast and a downwind-tapering tail. The size of ARTs is controlled by the diameter of the windward lithic clast, observed on the sub-decimeter to meter scale. Their distribution throughout the Campo de Piedra Pómez, and adjacent regions is determined by the ignimbrite clast content. ARTs develop under a uni-modal abrasion direction when lithic clasts are eroded out of the ignimbrite matrix, protrude from the surface, and shelter material directly behind the clast. As the surrounding material is eroded away, a downwind-tapered tail develops. Continued erosion of the adjacent surface leads to the undercutting of clasts, liberating them from the feature where, if small enough, the clasts can be transported downwind, leading to the destruction of the tail and ultimately the feature. This evolutionary sequence accounts not only for the morphology of the feature, but also the presence of loose clasts on the ignimbrite surface, which plays a role in the development of other enigmatic landforms in the area, such as periodic bedrock ridges, yardangs, and megaripples. The significance of the identification of ARTs is due to the necessity of uni-modal abrasion direction for their development, thereby making their orientation a diagnostic indicator of long-term aeolian abrasion direction. ARTs are likely analogs of features identified by MSL Curiosity Rover on Mars, possibly providing information on past and present wind regimes.

  19. Topical tar: Back to the future

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

    Paghdal, K.V.; Schwartz, R.A.

    2009-08-15

    The use of medicinal tar for dermatologic disorders dates back to the ancient times. Although coal tar is utilized more frequently in modern dermatology, wood tars have also been widely employed. Tar is used mainly in the treatment of chronic stable plaque psoriasis, scalp psoriasis, atopic dermatitis, and seborrheic dermatitis, either alone or in combination therapy with other medications, phototherapy, or both. Many modifications have been made to tar preparations to increase their acceptability, as some dislike its odor, messy application, and staining of clothing. One should consider a tried and true treatment with tar that has led to clearingmore » of lesions and prolonged remission times. Occupational studies have demonstrated the carcinogenicity of tar; however, epidemiologic studies do not confirm similar outcomes when used topically. This article will review the pharmacology, formulations, efficacy, and adverse effects of crude coal tar and other tars in the treatment of selected dermatologic conditions.« less

  20. Provenance of aeolian sands in the Hetao Plain, northwestern China

    NASA Astrophysics Data System (ADS)

    Yang, Xingchen; Cai, Maotang; Ye, Peisheng; Ye, Mengni; Li, Chenglu; Wu, Hang; Lu, Jing; Wang, Tao; Zhao, Zhirong; Luzhou, Yangfan; Liu, Chao

    2018-06-01

    Patches of aeolian sand are distributed throughout the Hetao Plain, which pose threats to farming and agriculture. Identification of the provenance of the aeolian sands may help with efforts to alleviate ecological stress in Inner Mongolia and in the paleoenvironmental interpretation of sandy sequences. This study uses geochemical data to determine the provenance of aeolian sands from the Hetao Plain. Provenance discrimination diagrams revealed that the aeolian sands were mainly derived from mixed source felsic granites and granodiorites, which have undergone weak sedimentary recycling. The chemical index of alteration and A-CN-K data indicated that the aeolian sediments were transported over a short distance. Comparison of trace element and rare earth element (REE) ratios of the aeolian sands with rock samples from potential source areas has revealed that aeolian sand deposits in the Hetao Plain were mainly derived from Sertengshan and Yellow River sediments. The Langshan and Ordos Plateau may represent additional sand sources for the Hetao Plain.

  1. Abstracts for the Planetary Geology Field Conference on Aeolian Processes

    NASA Technical Reports Server (NTRS)

    Greeley, R. (Editor); Black, D. (Editor)

    1978-01-01

    The Planetary Geology Field Conference on Aeolian Processes was organized at the request of the Planetary Geology Program office of the National Aeronautics and Space Administration to bring together geologists working on aeolian problems on earth and planetologists concerned with similar problems on the planets. Abstracts of papers presented at the conference are arranged herein by alphabetical order of the senior author. Papers fall into three broad categories: (1) Viking Orbiter and Viking Lander results on aeolian processes and/or landforms on Mars, (2) laboratory results on studies of aeolian processes, and (3) photogeology and field studies of aeolian processes on Earth.

  2. Gully annealing by aeolian sediment: field and remote-sensing investigation of aeolian-hillslope-fluvial interactions, Colorado River corridor, Arizona, USA

    USGS Publications Warehouse

    Sankey, Joel B.; Draut, Amy E.

    2014-01-01

    Processes contributing to development of ephemeral gully channels are of great importance to landscapes worldwide, and particularly in dryland regions where soil loss and land degradation from gully erosion pose long-term land-management problems. Whereas gully formation has been relatively well studied, much less is known of the processes that anneal gullies and impede their growth. This study of gully annealing by aeolian sediment, spanning 95 km along the Colorado River corridor in Glen, Marble, and Grand Canyon, Arizona, USA, employed field and remote sensing observations, including digital topographic modelling. Results indicate that aeolian sediment activity can be locally effective at counteracting gully erosion. Gullies are less prevalent in areas where surficial sediment undergoes active aeolian transport, and have a greater tendency to terminate in active aeolian sand. Although not common, examples exist in the record of historical imagery of gullies that underwent infilling by aeolian sediment in past decades and evidently were effectively annealed. We thus provide new evidence for a potentially important interaction of aeolian–hillslope–fluvial processes, which could affect dryland regions substantially in ways not widely recognized. Moreover, because the biologic soil crust plays an important role in determining aeolian sand activity, and so in turn the extent of gully development, this study highlights a critical role of geomorphic–ecologic interactions in determining arid-landscape evolution.

  3. Recent advances in research on the aeolian geomorphology of China's Kumtagh Sand Sea

    NASA Astrophysics Data System (ADS)

    Dong, Z.; Lv, P.

    2014-02-01

    The Kumtagh Sand Sea in the hyper-arid region of northwestern China remained largely unexplored until the last decade. It deserves study due to its significance in understanding the evolution of the arid environments in northwestern China, and even central Asia. Aeolian geomorphology in the sand sea has received unprecedented study in the last decade. Encouraging advances have been made in types of aeolian landforms, geological outlines, wind systems, the formation of aeolian landforms, several unique aeolian landforms, aeolian geomorphic regionalization, aeolian geomorphological heritages and tourism development, and aeolian sand hazards and their control. These advances expand our knowledge of aeolian geomorphology.

  4. Editorial - Special Issue on the Ninth International Conference on Aeolian Research - ICAR IX (Coastal Dune Processes and Aeolian Transport)

    NASA Astrophysics Data System (ADS)

    da Silva, Graziela Miot

    2018-04-01

    This special issue combines some of the papers related to coastal dune processes and aeolian sediment transport that were presented at the Ninth International Conference on Aeolian Research - ICAR IX. The conference was held between 4 and 8 of July 2016 in Mildura, Australia, organized by the International Society for Aeolian Research (ISAR) and convened by Adrian Chappell (Cardiff University), Craig Strong (Australian National University), Stephen Cattle (University of Sydney), Patrick Hesp (Flinders University), John Leys (New South Wales Office of Environment and Heritage), Lynda Petherick (University of Wellington) and Nick Webb (USDA-ARS Jornada Experimental Range).

  5. Monitoring aeolian desertification process in Hulunbir grassland during 1975-2006, Northern China.

    PubMed

    Guo, Jian; Wang, Tao; Xue, Xian; Ma, Shaoxiu; Peng, Fei

    2010-07-01

    The Hulunbir grassland experienced aeolian desertification expansion during 1975-2000, but local rehabilitation during 2000-2006. Northern China suffered severe aeolian desertification during the past 50 years. Hulunbir grassland, the best stockbreeding base in Northern China, was also affected by aeolian desertification. To evaluate the evolution and status of aeolian desertification, as well as its causes, satellite images (acquired in 1975, 1984, 2000, and 2006) and meteorological and socioeconomic data were interpreted and analyzed. The results show there was 2,345.7, 2,899.8, 4,053.9, and 3,859.6 km(2) of aeolian desertified land in 1975, 1984, 2000, and 2006, respectively. The spatial pattern dynamic had three stages: stability during 1975-1984, fast expansion during 1984-2000, and spatial transfer during 2000-2006. The dynamic degree of aeolian desertification is negatively related to its severity. Comprehensive analysis shows that the human factor is the primary cause of aeolian desertification in Hulunbir grassland. Although aeolian desertified land got partly rehabilitated, constant increase of extremely severe aeolian desertified land implied that current measures were not effective enough on aeolian desertification control. Alleviation of grassland pressure may be an effective method.

  6. Effects of river regulation on aeolian landscapes, Colorado River, southwestern USA

    USGS Publications Warehouse

    Draut, Amy E.

    2012-01-01

    Connectivity between fluvial and aeolian sedimentary systems plays an important role in the physical and biological environment of dryland regions. This study examines the coupling between fluvial sand deposits and aeolian dune fields in bedrock canyons of the arid to semiarid Colorado River corridor, southwestern USA. By quantifying significant differences between aeolian landscapes with and without modern fluvial sediment sources, this work demonstrates for the first time that the flow- and sediment-limiting effects of dam operations affect sedimentary processes and ecosystems in aeolian landscapes above the fluvial high water line. Dune fields decoupled from fluvial sand supply have more ground cover (biologic crust and vegetation) and less aeolian sand transport than do dune fields that remain coupled to modern fluvial sand supply. The proportion of active aeolian sand area also is substantially lower in a heavily regulated river reach (Marble–Grand Canyon, Arizona) than in a much less regulated reach with otherwise similar environmental conditions (Cataract Canyon, Utah). The interconnections shown here among river flow and sediment, aeolian sand transport, and biologic communities in aeolian dunes demonstrate a newly recognized means by which anthropogenic influence alters dryland environments. Because fluvial–aeolian coupling is common globally, it is likely that similar sediment-transport connectivity and interaction with upland ecosystems are important in other dryland regions to a greater degree than has been recognized previously.

  7. Beach- ridge internal architecture and use for Holocene sea-level reconstruction: A case study from the Miquelon-Langlade Isthmus (NW Atlantic)

    NASA Astrophysics Data System (ADS)

    Hein, C. J.; Billy, J.; Robin, N.; FitzGerald, D.; Certain, R.

    2017-12-01

    The internal architecture of beach-ridge systems can provide insight into processes ongoing during its period of formation, such as changing relative sea-level (RSL). The paraglacial beach-ridge plain at Miquelon-Langlade (south of Newfoundland - NW Atlantic) is an example of a well-preserved regressive barrier. Initiation of this plain correlates with a decrease in the rate of RSL rise (from +4.4 mm/yr to 1.3 mm/yr) at around 3000 years ago. The combination of stratigraphic (ground-penetrating radar and sediment cores), topographic (RTK-GPS) and chronologic (optically stimulated luminescence, OSL) data provide a detailed understanding of the constructional history of the plain. The internal architecture of individual beach ridges are characterized by sigmoidal configurations with seaward-dipping (2.3-4.7°) beds. Field mapping data reveal the processes associated with development of individual ridges in relation to sea level elevation. First, wave-built facies (sand-and-gravel) are deposited as beach berms, likely by fair-weather waves, with their elevations controlled by sea level and the swash height of constructive waves. This is followed by the accretion of aeolian sand deposits (foredunes) on the previous relict ridge, and then colonization by pioneer grasses. The well-defined contact between coarse-grained, wave-built facies and overlying aeolian deposits is used to demonstrate the dominant influence of RSL change in the development of the barrier system and, with chronology provided by OSL dating, produce a RSL curve for the 2500-year period of its formation. A net increase of 2.4 m in the surface elevation of wave-built facies is observed across the plain, corresponding to an overall increase in mean sea level through time. Three distinct periods can be distinguished: (1) an increase from 2.4 to 1 m below modern MSL between 2400 and 1500 years (rate: +1.3 mm/yr); (2) relatively stable or slowly rising RSL (<+0.2 mm/yr) from 1400 to 700 years; and (3) a

  8. Which Came First?

    NASA Image and Video Library

    2015-09-16

    The workings of the Martian winds are visible in this image of sand dunes trapped inside an unnamed crater in southern Terra Cimmeria captured by NASA Mars Reconnaissance Orbiter spacecraft. Many of the craters in the Southern highlands of Mars contain sand dunes, and HiRISE is still in the process of mapping these dunes and determining how active they are today. So far, the dunes in these craters appear to be a mixed bunch, with some dunes actively advancing while others seem to be frozen in place. This image will be compared to a previous picture, to see how these dunes have changed since 2008. The sand dunes are the large, branched ridges and dark patches that are conspicuous against the bright background, particularly in the northwest corner of our picture. There are also signs of two other wind-related processes: smaller, brighter ridges line the floor of the crater in regularly spaced rows. These are also windblown deposits, mysterious "transverse aeolian ridges" or TARs that are more common in the Martian tropics. Faint, irregular dark lines cross the dunes and the TARs, marking the tracks of dust devils that vacuum the surface during southern summer. So, which came first? We can untangle the history of these processes by looking at the picture more closely. Over most of the image, it is obvious that the dark sand dunes bury the bright TARs, meaning that the sand dunes are younger than the TARs. But this relationship is not so clear for the southernmost dune we see in this picture. Here, the TARs look like they extend into the dune and merge with ripples on the dune's surface, suggesting that the TARs might be younger than the dunes. The question can be resolved by carefully examining an enhanced color cutout. The TARs are brighter and redder than the sand dunes and this color persists on the crests of the TARs as the sand encroaches, burying the valleys first and then the slopes and finally the TAR crests. This tells us that the unusual appearance of the

  9. Synthesis on Quaternary aeolian research in the unglaciated eastern United States

    USGS Publications Warehouse

    Markewich, Helaine Walsh; Litwin, Ronald J.; Wysocki, Douglas A.; Pavich, Milan J.

    2015-01-01

    Late-middle and late Pleistocene, and Holocene, inland aeolian sand and loess blanket >90,000 km2 of the unglaciated eastern United States of America (USA). Deposits are most extensive in the Lower Mississippi Valley (LMV) and Atlantic Coastal Plain (ACP), areas presently lacking significant aeolian activity. They provide evidence of paleoclimate intervals when wind erosion and deposition were dominant land-altering processes. This study synthesizes available data for aeolian sand deposits in the LMV, the Eastern Gulf Coastal Plain (EGCP) and the ACP, and loess deposits in the Middle Atlantic Coastal Plain (MACP). Data indicate: (a) the most recent major aeolian activity occurred in response to and coincident with growth and decay of the Laurentide Ice Sheet (LIS); (b) by ∼40 ka, aeolian processes greatly influenced landscape evolution in all three regions; (c) aeolian activity peaked in OIS2; (d) OIS3 and OIS2 aeolian records are in regional agreement with paleoecological records; and (e) limited aeolian activity occurred in the Holocene (EGCP and ACP). Paleoclimate and atmospheric-circulation models (PCMs/ACMs) for the last glacial maximum (LGM) show westerly winter winds for the unglaciated eastern USA, but do not resolve documented W and SW winds in the SEACP and WNW and N winds in the MACP. The minimum areal extent of aeolian deposits in the EGCP and ACP is ∼10,000 km2. For the LMV, it is >80,000 km2. Based on these estimates, published PCMs/ACMs likely underrepresent the areal extent of LGM aeolian activity, as well as the extent and complexity of climatic changes during this interval.

  10. Synthesis on Quaternary aeolian research in the unglaciated eastern United States

    NASA Astrophysics Data System (ADS)

    Markewich, Helaine W.; Litwin, Ronald J.; Wysocki, Douglas A.; Pavich, Milan J.

    2015-06-01

    Late-middle and late Pleistocene, and Holocene, inland aeolian sand and loess blanket >90,000 km2 of the unglaciated eastern United States of America (USA). Deposits are most extensive in the Lower Mississippi Valley (LMV) and Atlantic Coastal Plain (ACP), areas presently lacking significant aeolian activity. They provide evidence of paleoclimate intervals when wind erosion and deposition were dominant land-altering processes. This study synthesizes available data for aeolian sand deposits in the LMV, the Eastern Gulf Coastal Plain (EGCP) and the ACP, and loess deposits in the Middle Atlantic Coastal Plain (MACP). Data indicate: (a) the most recent major aeolian activity occurred in response to and coincident with growth and decay of the Laurentide Ice Sheet (LIS); (b) by ∼40 ka, aeolian processes greatly influenced landscape evolution in all three regions; (c) aeolian activity peaked in OIS2; (d) OIS3 and OIS2 aeolian records are in regional agreement with paleoecological records; and (e) limited aeolian activity occurred in the Holocene (EGCP and ACP). Paleoclimate and atmospheric-circulation models (PCMs/ACMs) for the last glacial maximum (LGM) show westerly winter winds for the unglaciated eastern USA, but do not resolve documented W and SW winds in the SEACP and WNW and N winds in the MACP. The minimum areal extent of aeolian deposits in the EGCP and ACP is ∼10,000 km2. For the LMV, it is >80,000 km2. Based on these estimates, published PCMs/ACMs likely underrepresent the areal extent of LGM aeolian activity, as well as the extent and complexity of climatic changes during this interval.

  11. Evolution and diagnostic utility of aeolian rat-tails: A new type of abrasion feature on Earth and Mars

    NASA Astrophysics Data System (ADS)

    Favaro, Elena A.; Hugenholtz, Christopher H.; Barchyn, Thomas E.

    2017-10-01

    Aeolian rat-tails (ARTs) are a previously undocumented, regionally-ubiquitous aeolian abrasion feature observed on matrix-supported ignimbrite surfaces in the Puna Plateau of Northwest Argentina. ARTs consist of an abrasion-resistant lithic clast projecting above the surface with a lee tail or 'keel' in the more erodible matrix. Size is controlled by the dimensions of the windward lithic clast, ranging from centimetre to meter scale; spatial density varies with clast content, which may reflect variations in ignimbrite facies. Field observations suggest ARTs follow a definable evolutionary sequence. First, an abrasion-resistant lithic clast contained within the ignimbrite is exposed to abrasion at the surface. Impacts from abrading particles erode the softer ignimbrite matrix adjacent to the clast. The clast shelters the leeward surface under a unimodal abrasion direction, creating a tail that tapers downwind and elongates as the clast emerges. Clasts become dislodged from the matrix as the surrounding surface erodes, ultimately destroying the feature if the clast is small enough to be mobilized directly by wind or impacting particles. This evolutionary sequence explains the morphology of ARTs and the presence of loose clasts on the ignimbrite surface, which contributes to the development of other landforms in the region, such as periodic bedrock ridges, yardangs, and megaripples. Satellite and rover images suggest similar features also exist on Mars. Because the formation and preservation of ARTs is contingent on unimodal abrasion direction, their orientation can be used as an indicator of long-term aeolian sediment transport direction.

  12. Process for hydrogenation of hydrocarbon tars

    DOEpatents

    Dolbear, Geoffrey E.

    1978-07-18

    Hydrocarbon tars of high asphaltene content such as tars obtained from pyrolysis of coal are dissolved in a solvent formed from the hydrogenation of the coal tars, and the resultant mixture hydrogenated in the presence of a catalyst at a pressure from about 1500 to 5000 psig at a temperature from about 500.degree. F to about the critical temperature of the solvent to form a light hydrocarbon as a solvent for the tars. Hydrogen content is at least three times the amount of hydrogen consumed.

  13. Abrasion resistance of muscovite in aeolian and subaqueous transport experiments

    NASA Astrophysics Data System (ADS)

    Anderson, Calvin J.; Struble, Alexander; Whitmore, John H.

    2017-02-01

    Complementary aeolian and subaqueous transport experiments showed a trend in muscovite abrasion that may be useful for identifying ancient sandstones as aeolian or subaqueous in origin. We found that our experimental aeolian processes pulverized the micas quickly, while our subaqueous processes did not. In a pair of abrasion resistance experiments conducted with micaceous quartz sand, it was found that large muscovite grains were (1) reduced by aeolian processes to less than 500 μm in just 4 days, and (2) preserved by subaqueous processes to 610 ± 90 μm even after 356 days. At 20 days of aeolian transport no loose micas could be found even under the microscope, but after a year of subaqueous transport loose muscovite grains could still be seen with the naked eye. Thus, the occurrence and character of micas in a sandstone, particularly muscovite, may be helpful in determining the ancient depositional process.

  14. Introducing a New International Society of Aeolian Research

    USDA-ARS?s Scientific Manuscript database

    Aeolian research is long-standing and rapidly growing area of study where scientists of many disciplines meet to investigate the effects of wind on the surface of the Earth and other planetary bodies, such as Mars and Titan. Fields of study in aeolian research cover a broad spectrum ranging from dev...

  15. Analytical mesoscale modeling of aeolian sand transport

    NASA Astrophysics Data System (ADS)

    Lämmel, Marc; Kroy, Klaus

    2017-11-01

    The mesoscale structure of aeolian sand transport determines a variety of natural phenomena studied in planetary and Earth science. We analyze it theoretically beyond the mean-field level, based on the grain-scale transport kinetics and splash statistics. A coarse-grained analytical model is proposed and verified by numerical simulations resolving individual grain trajectories. The predicted height-resolved sand flux and other important characteristics of the aeolian transport layer agree remarkably well with a comprehensive compilation of field and wind-tunnel data, suggesting that the model robustly captures the essential mesoscale physics. By comparing the predicted saturation length with field data for the minimum sand-dune size, we elucidate the importance of intermittent turbulent wind fluctuations for field measurements and reconcile conflicting previous models for this most enigmatic emergent aeolian scale.

  16. Method for treatment of tar-bearing fuel gas

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

    Frauen, L.L.; Kasper, S.

    1986-01-07

    A process is described of producing a fuel gas which contains condensable tar vapor when it leaves a gasifier, the improvement wherein the tar-bearing gases are treated to remove tar therefrom. The process consists of: (a) continuously conducting hot fuel gas from a gasifier to and discharging it into a spray chamber where the hot tar-bearing gas is contacted with a fine spray of water thereby cooling the tar vapor and evaporating the water to produce a fog-like dispersion of tar in an atmosphere of fuel gas with the temperature in the spray chamber maintained above the dew point ofmore » water; (b) continuously transferring the fuel gas and the dispersion of tar and water to an electrostatic precipitator and precipitating therein at least most of the condensed tar as a liquid; (c) removing the liquid tar so precipitated and conducting at least most of it to a tar burner; (d) burning the tar with no more than the stoichiometric supply of oxygen provided by air to produce oxygen-free and tar-free hot combustion gases; (e) conducting the hot combustion gases directly into a mixer into which the fuel gas and water vapor flows from the precipitator, thereby adding to the fuel gas the sensible heat of the combustion gases; and (f) conducting the mixture so produced to a place of use as a hot fuel gas mixture.« less

  17. Tracer techniques in aeolian research: Approaches, applications, and challenges

    USDA-ARS?s Scientific Manuscript database

    Aeolian processes, the entrainment, transport and deposition of sediments by wind, impacts climate, biogeochemical cycles, food security, environmental quality and human health. Considering the multitude of interactions between aeolian processes and all the major components of the Earth system, ther...

  18. Aeolian sedimentation in the middle buntsandstein in the eifel north-south depression zone: Summary of the variability of sedimentary processes in a buntsandstein erg as a base for evaluation of the mutual relationships between aeolian sand seas and fluvial river systems in the mid-european buntsandstein

    NASA Astrophysics Data System (ADS)

    Mader, Detlef

    The spectrum of aeolian depositional subenvironments in the upper Middle Buntsandstein Karlstal-Schichten sequence in the Eifel North-South-zone at the western margin of the Mid-European Triassic Basin comprises trains of larger and higher narrowly-spaced dunes in sand seas, isolated smaller and lower widely-spaced dunes in floodplains and interdune playas, dry interdune sheet sands, damp interdune adhesive sandflats, wet interdune playa lakes, rainfall runoff watercourses and ephemeral channels cutting through the dune belt, and deflation gravel lag veneers. Distinction of aeolian and fluvial sediments within the succession of closely intertonguing wind- and water-laid deposits is possible by independent analysis of the conventional criteria and the more modern stratification styles. Thick cross-bedded aeolian sand sequences originate as barchanoid-type dunes which accumulate and migrate in the regime of narrow to wide unimodal southeasterly to southwesterly trade winds in low northern palaeolatitude in summer when the intertropical convergence zone is shifted to the north. The predominantly transverse-ridge dunes accrete mainly by grainfall and subcritical climbing of wind ripples, subordinately also by grainflow interfingering with grainfall. Horizontal-laminated aeolian sands form as sand sheets in dry interdune playas by subcritical migration of wind ripple trains, rarely also by plane bed accretion. Thin cross-bedded dune sands or horizontal-laminated aeolian sands capping fluvial cyclothems originate by deflation of emerged alluvial bar sands during low-water stages and subsequent accumulation of the winnowed sand as widely-spaced dunelets or chains of wind ripples in desiccated parts of the adjoining floodplain. The aeolian sand layers at the base of lacustrine cyclothems record migration of isolated little dunes across the dry playa floor at the beginning of a wetting-upwards cyclothem, with the sand deriving from deflation of fluvial incursions or

  19. Aeolian processes and the bioshpere: Interactions and feedback loops

    USDA-ARS?s Scientific Manuscript database

    Aeolian processes affect landform evolution, biogeochemical cycles, regional climate, human health, and desertification. The entrainment, transport and deposition of aeolian sediments are recognized as major drivers in the dynamics of the earth system and there is a growing interest in the scientif...

  20. On the origin of saline soils at Blackspring Ridge, Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Stein, Richard; Schwartz, Franklin W.

    1990-09-01

    Problems of soil salinity occur at Blackspring Ridge, Alberta, in four different settings. The most seriously affected area is at the base of the ridge where salinity appears as severe salt crusting on the surface, salt-tolerant vegetation, and areas of poor or no crop production. Blackspring Ridge is a structural bedrock high that is underlain by Upper Cretaceous sediment of the Horseshoe Canyon Formation. Bedrock is overlain by fluvial, glacial, lacustrine, and aeolian sediment. Piezometric data indicate that groundwater is recharged on and along the upper flanks of Blackspring Ridge and discharges in southern parts of a lacustrine plain that surrounds the ridge. Hydraulic conductivity data, water-level fluctuations, stable isotopes, and hydrochemical data indicate that the fractured near-surface bedrock and overlying thin-drift sediment constitute a zone of active groundwater flow within which salts are generated and transported. Water discharging from this shallow system evaporates and forms saline areas at the base of the ridge. The most seriously affected areas on the lacustrine plain coincide with places where the water table is less than 1.5m from the ground surface. A high water table occurs locally because of the changing topology of geologic units, and lows in the topographic surface that focus groundwater and surface water flows. Some proportion of the shallow groundwater salinized by evaporation is also transported down the flow system where it mixes with unevaporated water. Surface water, from snowmelt and precipitation events, dissolves salt that was deposited at the surface by evaporating groundwater and redistributes the salt to areas of lower elevation.

  1. Aeolian Desertification and its Control in Northern of China

    NASA Astrophysics Data System (ADS)

    Wang, Tao

    2017-04-01

    Aeolian desertification is land degradation through wind erosion mainly resulted from the excessive human activities in arid, semiarid and part of sub-humid regions in Northern China. To compare the analyses results of remote sensing data in late of 1950, 1975, 1987, 2000 and 2010, we can summarize that the development of aeolian desertified land in Northern China had being accelerated for 5 decades, as its annual expanded rate was 1,560 km2 during late of 1950 and 1975, 2,100 km2 between 1975 and 1988, 3,600 km2 from 1988 to 2000 and -1375 km2 from 2000 to 2010. The whole situation of desertification comes to be depraved before 2000 and to be improve after 2000. The human impact is much more active than natural one on the process of aeolian desertification which mainly incarnates on the changes of the landuse fashion (from rangeland to farmland) and enhance of landuse intensity (over-cultivation, over-grassing and over-fuelwood collection). The natural vegetation had been destroyed by the human activities that had accelerated to the development or/and control of aeolian desertification. China has made much progresses in understanding and combating aeolian desertification through many efforts for decades and there were many projects have been carried out. One of among them is the National Project of Grain for Green Program and more than 1000 counties in 22 provinces have been included into this project. The objective is to withdraw 3.67 million ha of dry land farming and degraded steppe, and 5.13 million ha of aeolian desertified land suited to reforestation and revegetation will be rehabilitated. There are about 8 million ha of lands under the threats of aeolian desertified land will be brought under control in the next ten years and 26.67 million ha of windbreaks will be planted. The total financial input is estimated to 75 billion Yuan (11 billion US) what is entirely from the central government.

  2. Laboratory Simulations of Martian and Venusian Aeolian Processes

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    1999-01-01

    With the flyby of the Neptune system by Voyager, the preliminary exploration of the Solar System was accomplished. Data have been returned for all major planets and satellites except the Pluto system. Results show that the surfaces of terrestrial planets and satellites have been subjected to a wide variety of geological processes. On solid- surface planetary objects having an atmosphere, aeolian processes are important in modifying their surfaces through the redistribution of fine-grained material by the wind. Bedrock may be eroded to produce particles and the particles transported by wind for deposition in other areas. This process operates on Earth today and is evident throughout the geological record. Aeolian processes also occur on Mars, Venus, and possibly Titan and Triton, both of which are outer planet satellites that have atmospheres. Mariner 9 and Viking results show abundant wind-related landforms on Mars, including dune fields and yardangs (wind-eroded hills). On Venus, measurements made by the Soviet Venera and Vega spacecraft and extrapolations from the Pioneer Venus atmospheric probes show that surface winds are capable of transporting particulate materials and suggest that aeolian processes may operate on that planet as well. Magellan radar images of Venus show abundant wind streaks in some areas, as well as dune fields and a zone of possible yardangs. The study of planetary aeolian processes must take into account diverse environments, from the cold, low-density atmosphere of Mars to the extremely hot, high- density Venusian atmosphere. Factors such as threshold wind speeds (minimum wind velocity needed to move particles), rates of erosion and deposition, trajectories of windblown particles, and aeolian flow fields over various landforms are all important aspects of the problem. In addition, study of aeolian terrains on Earth using data analogous to planetary data-collection systems is critical to the interpretation of spacecraft information and

  3. 40 CFR 721.10532 - Tar, brown coal.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Tar, brown coal. 721.10532 Section 721... Tar, brown coal. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as tar, brown coal (PMN P-12-167, CAS No. 101316-83-0) is subject to...

  4. 40 CFR 721.10532 - Tar, brown coal.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Tar, brown coal. 721.10532 Section 721... Tar, brown coal. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as tar, brown coal (PMN P-12-167, CAS No. 101316-83-0) is subject to...

  5. Beach ridge sedimentology: field observation and palaeoenvironmental interpretation for Anegada Island, British Virgin Islands.

    NASA Astrophysics Data System (ADS)

    Cescon, Anna Lisa; Cooper, J. Andrew G.; Jackson, Derek W. T.

    2014-05-01

    Beach ridge landforms have been observed in different environments and in settings that range from polar to tropical. Their stratigraphy and sedimentology has received a limited amount of discussion in the literature (Tamura, 2012). In coastal geomorphology a beach ridge can be seen as a transitional deposit between onshore and offshore environments. They are regarded as representing high level wave action along a coastline. In the Caribbean the origin of beach ridges has been variously attributed to one of three extreme wave events: extreme swell, extreme storm or tsunami waves. Beach ridges are arranged in beach ridge plains where there is succession of the landforms and can be several kilometres long. Beach ridge accumulation is not continuous and the coast shows alternating accretion and erosion periods. The use of beach ridges as palaeostorm archives is therefore not straightforward. The temporal continuity of beach ridge formation is being assessed on the beach ridge plains of Anegada, British Virgin Islands (Lesser Antilles). This carbonate platform surrounded by a fringing reef contains two beach ridge plains. There are more than 30 ridges in the Atlantic facing- coast and around 10 in the south, Caribbean- facing coast. The sediments of the modern beaches are dominated by the sand fraction and are 100% biogenic origin due to the isolation of Anegada from terrestrial sediment sources. The beach ridge sections have been studied in different area of Anegada beach ridge plains and present low angle seaward-dipping bedding. The sand fraction is dominant in the stratigraphy with a few intact shells. At only one site were coral pebbles deposited in association with the sand fraction. Aeolian deposits represent the upper part of the beach ridges and reflect the stabilization of the beach ridges with ongoing accretion. The sedimentology of the contemporary beach and dunes will be discussed in terms of their implications for understanding beach ridge genesis and its

  6. Holocene aeolian activity in the Gonghe Basin, north-eastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Stauch, Georg; Lai, Zhongping; Lehmkuhl, Frank; Schulte, Philipp

    2016-04-01

    The Gonghe Basin is located on the north-eastern edge of Tibetan Plateau and has a mean altitude of 3000 m asl. With a size of 20.000 km² it is the largest intramontane Basin on the north-eastern Plateau. The well-studied Qinghai Basin is situated north of the Basin, while the drier central Plateau is further south-west. Previous research indicated an early onset of the aeolian accumulation in the Qinghai Basin at around 18 ka while in the areas further to the south-west aeolian archives date back only to the beginning of the Holocene. First new OSL ages from aeolian sand and loess indicate a intermediate timing of the aeolian accumulation in the Gonghe Basin at the transition from the late glacial to the Holocene. Late glacial and early Holocene ages of aeolian sediments were hitherto associated with wetter climate conditions caused by the strengthening of the Asian summer monsoon. Higher moisture availability resulted in an increased vegetation cover, leading to the permanent stabilization of the aeolian sediments. Under glacial climate conditions a constant remobilization of the sediments can be assumed. The new OSL ages from the Gonghe Basin indicate a progressive shift of the monsoonal strength in westward directions during the late glacial until the early Holocene.

  7. Periodic Trajectories in Aeolian Sand Transport

    NASA Astrophysics Data System (ADS)

    Valance, A.; Jenkins, J. T.

    2014-12-01

    Saltation is the primary mode of aeolian sand transport and refers to the hoping motion of grains over the bed [1]. We develop a simple model for steady, uniform transport in aeolian saltation over a horizontal bed that is based on the computation of periodic particle trajectories in a turbulent shearing flow [2]. The wind and the particles interact through drag, and the particles collide with the bed. We consider collisions with a rigid, bumpy bed, from which the particles rebound, and an erodible particle bed, for which a collision involves both rebound and particle ejection. The difference in the nature of the collisions results in qualitative differences in the nature of the solutions for the periodic trajectories and, in particular, to differences in the dependence of the particle flow rate on the strength of the turbulent shearing. We also discuss the pertinence of this model to describe bedload transport in water. References:[1] R. A. Bagnold, « The physics of blown sand and desert dunes » , Methuen, New York (1941).[2] J.T Jenkins and A. Valance. Periodic trajectories in Aeolian saltation transport. Physics of Fluids, 2014, 26, pp. 073301

  8. Responses of aeolian desertification to a range of climate scenarios in China

    NASA Astrophysics Data System (ADS)

    Wang, Xunming; Hua, Ting; Ma, Wenyong

    2016-06-01

    Aeolian desertification plays an important role in earth-system processes and ecosystems, and has the potential to greatly impact global food production. The occurrence of aeolian desertification has traditionally been attributed to increases in wind speed and temperature and decreases in rainfall. In this study, by integrating the aeolian desertification monitoring data and climate and vegetation indices, we found that although aeolian desertification is influenced by complex climate patterns and human activities, increases in rainfall and temperature and decreases in wind speed may not be the key factors of aeolian desertification controls in some regions of China. Our results show that, even when modern technical approaches are used, different approaches to desertification need to be applied to account for regional differences. These results have important implications for future policy decisions on how best to combat desertification.

  9. Treating tar sands formations with karsted zones

    DOEpatents

    Vinegar, Harold J.; Karanikas, John Michael

    2010-03-09

    Methods for treating a tar sands formation are described herein. The tar sands formation may have one or more karsted zones. Methods may include providing heat from one or more heaters to one or more karsted zones of the tar sands formation to mobilize fluids in the formation. At least some of the mobilized fluids may be produced from the formation.

  10. Tar Management and Recycling in Biomass Gasification and Syngas Purification

    NASA Astrophysics Data System (ADS)

    McCaffrey, Zach

    Removal of tars is critical to the design and operation of biomass gasification systems as most syngas utilization processing equipment (e.g. internal combustion engines, gas turbines, fuel cells, and liquid fuel synthesis reactors) have a low tolerance for tar. Capturing and disposal of tar is expensive due to equipment costs, high hazardous waste disposal costs where direct uses cannot be found, and system energy losses incurred. Water scrubbing is an existing technique commonly used in gasification plants to remove contaminants and tar; however using water as the absorbent is non-ideal as tar compounds have low or no water solubility. Hydrophobic solvents can improve scrubber performance and this study evaluated tar solubility in selected solvents using slip-streams of untreated syngas from a laboratory fluidized bed reactor operated on almond composite feedstock using both air and steam gasification. Tar solubility was compared with Hansen's solubility theory to examine the extent to which the tar removal can be predicted. As collection of tar without utilization leads to a hazardous waste problem, the study investigated the effects of recycling tars back into the gasifier for destruction. Prior to experiments conducted on tar capture and recycle, characterizations of the air and steam gasification of the almond composite mix were made. This work aims to provide a better understanding of tar collection and solvent selection for wet scrubbers, and to provide information for designing improved tar management systems for biomass gasification.

  11. Ranking methodology for determining the relative favorability for commercial development of US tar-sand deposits

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

    Aamodt, P.L.; Freiwald, J.G.

    1983-03-01

    As a part of the DOE's program to stimulate petroleum production from unconventional sources, the Los Alamos National Laboratory has developed a methodology to compare and rank tar sand deposits, based on their suitability for commercial development. Major categories influencing favorability were identified and evaluated to determine their individual and collective impacts. To facilitate their evaluation, deposit characteristics, extraction technologies, environmental controls, and institutional constraints were broken down into their elements. The elements were assessed singly and in interactive groups to determine their influence on favorability for commercial development. A numerical value was assigned each element to signify its estimatedmore » importance relative to the other elements. Eight tar sand deposits were evaluated using only one major category, deposit characteristics. This initial, and only partial favorability assessment, was solely a test of the methodology, and it was considered successful. Because only one of the four major categories was used for this initial favorability ranking, and also because the available deposit characteristic data were barely adequate for the test, these first results should be used only as an example of how the methodology is to be applied when more complete data are available. The eight deposits and their relative favorability rankings for commercial development, based only on the deposit characteristics, are Sunnyside, Utah; Asphalt Ridge, Utah; Edna, California; Santa Rosa, New Mexico; Tar Sand Triangle, Utah; PR Spring, Utah; Uvalde, Texas; and circle cliffs, Utah.« less

  12. Method for filtering solvent and tar sand mixtures

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

    Kelterborn, J. C.; Stone, R. A.

    1985-09-03

    A method for filtering spent tar sands from a bitumen and organic solvent solution comprises separating the solution into two streams wherein the bulk of the coarser spent tar sand is in a first stream and has an average particle size of about 10 to about 100 mesh and the bulk of the finer spent tar sand is in a second stream; producing a filter cake by filtering the coarser spent tar sand from the first stream; and filtering the finer spent tar sand from the second stream with the filter cake. The method is particularly useful for filtering solutionsmore » of bitumen extracted from bitumen containing diatomite, spent diatomite and organic solvent.« less

  13. Final safety assessment of Coal Tar as used in cosmetics.

    PubMed

    2008-01-01

    Coal Tar is a semisolid by-product obtained in the destructive distillation of bituminous coal, which functions in cosmetic products as a cosmetic biocide and denaturant--antidandruff agent is also listed as a function, but this is considered an over-the-counter (OTC) drug use. Coal Tar is a nearly black, viscous liquid, heavier than water, with a naphthalene-like odor and a sharp burning taste, produced in cooking ovens as a by-product in the manufacture of coke. Crude Coal Tar is composed of 48% hydrocarbons, 42% carbon, and 10% water. In 2002, Coal Tar was reported to the Food and Drug Administration (FDA) to be used in four formulations, all of which appear to be OTC drug products. Coal Tar is monographed by the FDA as Category I (safe and effective) OTC drug ingredient for use in the treatment of dandruff, seborrhoea, and psoriasis. Coal Tar is absorbed through the skin of animals and humans and is systemically distributed. In short-term studies, mice fed a diet containing Coal Tar found it unpalatable, but no adverse effects were reported other than weight loss; rats injected with Coal Tar experienced malaise in one study and decreased water intake and increased liver weights in another; rabbits injected with Coal Tar residue experienced eating avoidance, respiratory difficulty, sneezing, and weight loss. In a subchronic neurotoxicity study using mice, a mixture of phenols, cresols, and xylenols at concentrations approximately equal to those expected in Coal Tar extracts produced regionally selective effects, with a rank order of corpus striatum > cerebellum > cerebral cortex. Coal Tar applied to the backs of guinea pigs increases epidermal thickness. Painting female rabbits with tar decreases the absolute and relative weights of the ovaries and decreased the number of interstitial cells in the ovary. Four therapeutic Coal Tar preparations used in the treatment of psoriasis were mutagenic in the Ames assay. Urine and blood from patients treated with Coal Tar

  14. Smokers' knowledge and understanding of advertised tar numbers: health policy implications.

    PubMed

    Cohen, J B

    1996-01-01

    This article examines health policy implications of providing smokers with numerical tar yield information in cigarette advertising. Results of a national probability telephone survey regarding smokers' knowledge and understanding of numerical tar yields and deliveries are reported. Few smokers knew the tar level of their own cigarettes (the exception being smokers of 1- to 5-mg tar cigarettes), and a majority could not correctly judge the relative tar levels of cigarettes. Smokers were unsure whether switching to lower-tar cigarettes would reduce their personal health risks. Many smokers relied on absolute numbers in making trade-offs between number of cigarettes smoked and their tar levels, thus confusion machine-rated tar-yields with actual amounts ingested. The wisdom of the present method of providing tar and nicotine numbers in ads and recommendations for modifying the test protocol are now under discussion. This research indicates that these tar numbers and their implications are poorly understood. The paper recommends revisions in tar ratings to make them more useful and a required statement on cigarette packages to more explicitly relate tar levels to major health risks.

  15. A Process-Based Transport-Distance Model of Aeolian Transport

    NASA Astrophysics Data System (ADS)

    Naylor, A. K.; Okin, G.; Wainwright, J.; Parsons, A. J.

    2017-12-01

    We present a new approach to modeling aeolian transport based on transport distance. Particle fluxes are based on statistical probabilities of particle detachment and distributions of transport lengths, which are functions of particle size classes. A computational saltation model is used to simulate transport distances over a variety of sizes. These are fit to an exponential distribution, which has the advantages of computational economy, concordance with current field measurements, and a meaningful relationship to theoretical assumptions about mean and median particle transport distance. This novel approach includes particle-particle interactions, which are important for sustaining aeolian transport and dust emission. Results from this model are compared with results from both bulk- and particle-sized-specific transport equations as well as empirical wind tunnel studies. The transport-distance approach has been successfully used for hydraulic processes, and extending this methodology from hydraulic to aeolian transport opens up the possibility of modeling joint transport by wind and water using consistent physics. Particularly in nutrient-limited environments, modeling the joint action of aeolian and hydraulic transport is essential for understanding the spatial distribution of biomass across landscapes and how it responds to climatic variability and change.

  16. The temporal relationship between advertising and sales of low-tar cigarettes.

    PubMed

    Reed, Mark B; Anderson, Christy M; Burns, David M

    2006-12-01

    To determine whether a temporal relationship exists between the advertising and sales of low-tar cigarettes. It was hypothesised that increases in the advertising of low-tar cigarettes would precede increases in sales for these cigarettes. The themes of cigarette advertisements were reviewed and coded for 20 low-tar cigarette brands advertised in 13 widely read magazines in the US between 1960 and 1996. These 20 brands represented most of the low-tar cigarette advertisements and cigarette sales from 1967 to 1996. Cigarette sales data were obtained from the 1994 Maxwell report that summarises all cigarette sales from 1925 to 1990. If the advertisement referred to the low-tar attributes of the cigarette advertised, the advertisement was coded as having a low-tar theme and was included in the analysis. Five different graphical presentations of the relationship between the advertising and sales of the 20 low-tar cigarette brands showed a temporal relationship between low-tar advertising and sales for these brands. This relationship was observed for brands that introduced a low-tar alternative into an existing brand family (eg, Marlboro Light) and for new exclusively low-tar brands (eg, Carlton). Despite large increases in the advertising for the exclusively low-tar brands, sales of these brands remained low relative to sales of the low-tar alternative brands. Increases in print advertising of 20 of the most popular low-tar cigarette brands were followed by increases in sales for these cigarettes. Despite increases in the advertising of exclusively low-tar brands in the mid-1970s and early 1980s, the sales of these brands never matched the sales of the low-tar alternative brands. This suggests that it may have been easier to get smokers to switch to low-tar brands within a brand family compared with entirely new low-tar brands. Over the past 30 years, the marketing of low-tar cigarettes as a healthier alternative to higher-tar cigarettes has resulted in these brands

  17. Character and provenance of aeolian sediments in northeast Thailand

    NASA Astrophysics Data System (ADS)

    Nichol, Janet E.; Nichol, Douglas W.

    2015-12-01

    Aeolian activity is not generally associated with the humid tropics, and although reports of loess-like soils in various locations in southeast Asia exist, these mainly lack the detailed analysis to set them in meaningful spatial or historical context. This paper examines the red and yellow sandy sediments of the Khorat Plateau in northeast Thailand which have been variously referred to as 'cover sands', 'loessial soils' or 'loess'. The sediments are referred to as having alluvial, biological as well as aeolian origin, and a date of 9-35 ka is reported. The study compares the Khorat sediments physically and geochemically with loess and aeolian sediments from other regions, as well as with other sites in southeast Asia which are reported here. The moderate degree of particle sorting and unimodal sizes of the sediments along with a sub-spherical sub-rounded form, supports previous diagnoses of an aeolian origin. Geochemical analysis of the Khorat sediments indicates severe depletion in both mobile and immobile elements, which are even more depleted than other southeast Asian loessic soils examined. This depletion, along with the only moderate particle sorting, suggests the source of the sediments to be the local weathered sandstones outcropping around the edge of the Khorat Plateau. The dissimilarity of the Khorat sediments from Upper Continental Crust (UCC) elemental values supports this, as homogenisation would occur if diverse source areas were involved. The study suggests that aeolian sediments of humid tropical regions warrant more attention as climate proxy markers, due to the dissimilarity between the present climate and conditions required for their formation.

  18. Element geochemical analysis of the contribution of aeolian sand to suspended sediment in desert stream flash floods.

    PubMed

    Jia, Xiaopeng; Wang, Haibing

    2014-01-01

    The interaction of wind and water in semiarid and arid areas usually leads to low-frequency flash flood events in desert rivers, which have adverse effects on river systems and ecology. In arid zones, many aeolian dune-fields terminate in stream channels and deliver aeolian sand to the channels. Although aeolian processes are common to many desert rivers, whether the aeolian processes contribute to fluvial sediment loss is still unknown. Here, we identified the aeolian-fluvial cycling process responsible for the high rate of suspended sediment transport in the Sudalaer desert stream in the Ordos plateau of China. On the basis of element geochemistry data analysis, we found that aeolian sand was similar to suspended sediment in element composition, which suggests that aeolian sand contributes to suspended sediment in flash floods. Scatter plots of some elements further confirm that aeolian sand is the major source of the suspended sediment. Factor analysis and the relation between some elements and suspended sediment concentration prove that the greater the aeolian process, the higher the suspended sediment concentration and the greater the contribution of aeolian sand to suspended sediment yield. We conclude that aeolian sand is the greatest contributor to flash floods in the Sudalaer desert stream.

  19. Element Geochemical Analysis of the Contribution of Aeolian Sand to Suspended Sediment in Desert Stream Flash Floods

    PubMed Central

    Wang, Haibing

    2014-01-01

    The interaction of wind and water in semiarid and arid areas usually leads to low-frequency flash flood events in desert rivers, which have adverse effects on river systems and ecology. In arid zones, many aeolian dune-fields terminate in stream channels and deliver aeolian sand to the channels. Although aeolian processes are common to many desert rivers, whether the aeolian processes contribute to fluvial sediment loss is still unknown. Here, we identified the aeolian-fluvial cycling process responsible for the high rate of suspended sediment transport in the Sudalaer desert stream in the Ordos plateau of China. On the basis of element geochemistry data analysis, we found that aeolian sand was similar to suspended sediment in element composition, which suggests that aeolian sand contributes to suspended sediment in flash floods. Scatter plots of some elements further confirm that aeolian sand is the major source of the suspended sediment. Factor analysis and the relation between some elements and suspended sediment concentration prove that the greater the aeolian process, the higher the suspended sediment concentration and the greater the contribution of aeolian sand to suspended sediment yield. We conclude that aeolian sand is the greatest contributor to flash floods in the Sudalaer desert stream. PMID:25089295

  20. 7 CFR 3201.76 - Asphalt and tar removers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Asphalt and tar removers. 3201.76 Section 3201.76... Designated Items § 3201.76 Asphalt and tar removers. (a) Definition. Cleaning agents designed to remove asphalt or tar from equipment, roads, or other surfaces. (b) Minimum biobased content. The Federal...

  1. 7 CFR 3201.76 - Asphalt and tar removers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Asphalt and tar removers. 3201.76 Section 3201.76... Designated Items § 3201.76 Asphalt and tar removers. (a) Definition. Cleaning agents designed to remove asphalt or tar from equipment, roads, or other surfaces. (b) Minimum biobased content. The Federal...

  2. Smokers' knowledge and understanding of advertised tar numbers: health policy implications.

    PubMed Central

    Cohen, J B

    1996-01-01

    OBJECTIVES. This article examines health policy implications of providing smokers with numerical tar yield information in cigarette advertising. METHODS. Results of a national probability telephone survey regarding smokers' knowledge and understanding of numerical tar yields and deliveries are reported. RESULTS. Few smokers knew the tar level of their own cigarettes (the exception being smokers of 1- to 5-mg tar cigarettes), and a majority could not correctly judge the relative tar levels of cigarettes. Smokers were unsure whether switching to lower-tar cigarettes would reduce their personal health risks. Many smokers relied on absolute numbers in making trade-offs between number of cigarettes smoked and their tar levels, thus confusion machine-rated tar-yields with actual amounts ingested. CONCLUSIONS. The wisdom of the present method of providing tar and nicotine numbers in ads and recommendations for modifying the test protocol are now under discussion. This research indicates that these tar numbers and their implications are poorly understood. The paper recommends revisions in tar ratings to make them more useful and a required statement on cigarette packages to more explicitly relate tar levels to major health risks. PMID:8561236

  3. The Australian tar derby: the origins and fate of a low tar harm reduction programme

    PubMed Central

    King, W; Carter, S; Borland, R; Chapman, S; Gray, N

    2003-01-01

    Objective: To document the development of the low tar harm reduction programme in Australia, including tobacco industry responses. Data sources: Tobacco industry documents, retail tobacco journals, newspapers, medical journals, and Anti-Cancer Council of Victoria (ACCV) newsletters and archival records. Study selection: Documents on the strategies and knowledge bases of the ACCV, other Australian health authorities, and the tobacco industry. Results: The ACCV built a durable system for measuring and publicising the tar and nicotine yields of Australian cigarettes and influencing their development. The tobacco industry initially sought to block the development of this system but later appeared to cooperate with it, as is evidenced by the current market dominance of low tar brands. However, behind the scenes, the industry used its substantial knowledge advantage regarding compensatory smoking and its ability to re-engineer cigarettes to gain effective control of the system and subvert the ACCV's objectives. Conclusions: Replacement of the low tar programme with new means of minimising the harms from cigarette smoking should be a policy priority for the Australian government. This will require regulation, rather than further voluntary agreements, and stringent monitoring of successor programmes will be necessary. PMID:14645950

  4. The temporal relationship between advertising and sales of low‐tar cigarettes

    PubMed Central

    Reed, Mark B; Anderson, Christy M; Burns, David M

    2006-01-01

    Objective and hypothesis To determine whether a temporal relationship exists between the advertising and sales of low‐tar cigarettes. It was hypothesised that increases in the advertising of low‐tar cigarettes would precede increases in sales for these cigarettes. Methods The themes of cigarette advertisements were reviewed and coded for 20 low‐tar cigarette brands advertised in 13 widely read magazines in the US between 1960 and 1996. These 20 brands represented most of the low‐tar cigarette advertisements and cigarette sales from 1967 to 1996. Cigarette sales data were obtained from the 1994 Maxwell report that summarises all cigarette sales from 1925 to 1990. If the advertisement referred to the low‐tar attributes of the cigarette advertised, the advertisement was coded as having a low‐tar theme and was included in the analysis. Results Five different graphical presentations of the relationship between the advertising and sales of the 20 low‐tar cigarette brands showed a temporal relationship between low‐tar advertising and sales for these brands. This relationship was observed for brands that introduced a low‐tar alternative into an existing brand family (eg, Marlboro Light) and for new exclusively low‐tar brands (eg, Carlton). Despite large increases in the advertising for the exclusively low‐tar brands, sales of these brands remained low relative to sales of the low‐tar alternative brands. Conclusions Increases in print advertising of 20 of the most popular low‐tar cigarette brands were followed by increases in sales for these cigarettes. Despite increases in the advertising of exclusively low‐tar brands in the mid‐1970s and early 1980s, the sales of these brands never matched the sales of the low‐tar alternative brands. This suggests that it may have been easier to get smokers to switch to low‐tar brands within a brand family compared with entirely new low‐tar brands. Over the past 30 years, the marketing of low‐tar

  5. Source-to-sink cycling of aeolian sediment in the north polar region of Mars

    NASA Astrophysics Data System (ADS)

    Ewing, R. C.; Kocurek, G.

    2012-12-01

    Aeolian sand dunes are prominent features on the landscapes of Earth, Mars, Venus and Titan and sedimentary deposits interpreted as aeolian in origin are found in the rock records of Earth and Mars. The widespread occurrence of aeolian dunes on the surface of these worlds and within their deep-time depositional records suggests that aeolian systems are and likely have been a default depositional environment for the Solar System. Within an aeolian source-to-sink context, we hypothesize that planet-specific boundary conditions strongly impact production, transport, accumulation and preservation of aeolian sediment, whereas dunes and dune-field patterns remain largely similar. This hypothesis is explored within the north polar region of Mars, which hosts the most extensive aeolian dune fields and aeolian sedimentary deposits yet recognized on Mars and appears to be a region of dynamic source-to-sink cycling of aeolian sediments. The Planum Boreum Cavi Unit rests beneath north polar ice cap of Mars and is composed of several hundred meters of niveo-aeolian dune cross-stratification. The overall architecture of the unit consists of sets of preserved dune topography with an upward increase in the abundance of ice. Dune sets are defined by stabilized, polygonally fractured bounding surfaces, erosional bounding surfaces and typical internal lee foresets made of sediment and ice. The accumulation of the Cavi Unit is interpreted as occurring through freezing and serves as an example of a cold temperature boundary condition on aeolian sediment accumulation. Preservation of the Cavi Unit arises because of deposition of the overlying ice cap and contrasts with preservation of aeolian sediment on Earth, which is largely driven by eustasy and tectonics. The Cavi Unit is thought to be one source of sediment for the north polar Olympia Undae Dune Field. The region of Olympia Undae near the Cavi Unit shows a reticulate dune field pattern composed of two sets of nearly orthogonal

  6. Potential impacts to perennial springs from tar sand mining, processing, and disposal on the Tavaputs Plateau, Utah, USA.

    PubMed

    Johnson, William P; Frederick, Logan E; Millington, Mallory R; Vala, David; Reese, Barbara K; Freedman, Dina R; Stenten, Christina J; Trauscht, Jacob S; Tingey, Christopher E; Kip Solomon, D; Fernandez, Diego P; Bowen, Gabriel J

    2015-11-01

    Similar to fracking, the development of tar sand mining in the U.S. has moved faster than understanding of potential water quality impacts. Potential water quality impacts of tar sand mining, processing, and disposal to springs in canyons incised approximately 200 m into the Tavaputs Plateau, at the Uinta Basin southern rim, Utah, USA, were evaluated by hydrogeochemical sampling to determine potential sources of recharge, and chemical thermodynamic estimations to determine potential changes in transfer of bitumen compounds to water. Because the ridgetops in an area of the Tavaputs Plateau named PR Spring are starting to be developed for their tar sand resource, there is concern for potential hydrologic connection between these ridgetops and perennial springs in adjacent canyons on which depend ranching families, livestock, wildlife and recreationalists. Samples were collected from perennial springs to examine possible progression with elevation of parameters such as temperature, specific conductance, pH, dissolved oxygen, isotopic tracers of phase change, water-rock interaction, and age since recharge. The groundwater age dates indicate that the springs are recharged locally. The progression of hydrogeochemical parameters with elevation, in combination with the relatively short groundwater residence times, indicate that the recharge zone for these springs includes the surrounding ridges, and thereby suggests a hydrologic connection between the mining, processing, disposal area and the springs. Estimations based on chemical thermodynamic approaches indicate that bitumen compounds will have greatly enhanced solubility in water that comes into contact with the residual bitumen-solvent mixture in disposed tailings relative to water that currently comes into contact with natural tar. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Coupled Modeling and Field Approach to Explore Patterns of Barrier Ridge and Swale Development

    NASA Astrophysics Data System (ADS)

    Ciarletta, D. J.; Lorenzo-Trueba, J.; Shawler, J. L.; Hein, C. J.

    2017-12-01

    Previous work has suggested the morphologies of barrier ridge and swale systems potentially reflect the environmental conditions under which they developed, especially in response to sediment budget. We use this inference to examine progradational dune systems on barriers along the USA Mid-Atlantic coast, constructing a simple morphodynamic model to capture the magnitude of changes in key processes affecting the pattern of ridge and swale development. Based on our initial investigation, we demonstrate a range of potential morphological patterns generated by the interaction of longshore transport, accommodation, overwash, aeolian sand flux, and vegetation controls. The patterns are based on three basic cross-sectional morphologies describing the spacing and width of ridges. Regularly spaced ridges of roughly equal width are defined as washboards; wide platform-like ridges or complex multi-ridge dunes are described as tables; and wide swaths of open sand or poorly developed dunes are identified as pans. The inclusion of overwash, in competition with the other processes, further allows the creation of infilled swales, or baffled structures, as well as inter-ridge and backbarrier fans/flats. Model outcomes are validated via comparison to observations from barriers in Virginia, Maryland, and New Jersey. In particular, historical (post-1850) mapping of the evolution of the Fishing Point spit (Assateague Island) reveals the ability of the model to approximate the growth of structures seen in the field. We then apply the model to the development of a prehistoric progradational system on Parramore Island, VA, using field stratigraphic/chronologic data to supply input parameters and begin predictively quantifying past changes in longshore transport and accommodation. Our investigations suggest that modeling patterns of ridge and swale development preserved on modern coasts could result in novel approaches to employ barriers as archives of past environmental/climate forcing.

  8. Site handbook: data acquisition system information, Shelly Ridge Program Center for the Girl Scouts of greater Philadelphia, Miquon, Pennsylvania

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

    Not Available

    1985-01-01

    Data were collected at the Shelly Ridge Girl Scout Center using an Aeolian Kinetics PDL-24 data acquisition system. Instantaneous data readings were recorded each 15 seconds by the microprocessor. These channel readings were then averaged to produce hourly values which were then stored on an audio cassette. These hourly data were then transcribed to the AIAF archive. The Girl Scout Center features an 861 square foot unvented Trombe wall, a direct gain sunspace, and two rooftop collectors for heating domestic water.

  9. Landscape evolution on Mars - A model of aeolian denudation in Gale Crater

    NASA Astrophysics Data System (ADS)

    Day, M. D.; Kocurek, G.; Grotzinger, J. P.

    2015-12-01

    Aeolian erosion has been the dominant geomorphic agent to shape the surface of Mars for the past ~3.5 billion years. Although individual geomorphic features evidencing aeolian activity are well understood (e.g., yardangs, dune fields, and wind streaks), landscapes formed by aeolian erosion remain poorly characterized. Intra-crater sedimentary mounds are hypothesized to have formed by wind deflation of craters once filled with flat-lying strata, and, therefore, should be surrounded by landscapes formed by aeolian erosion. Here we present a landscape evolution model that provides both an initial characterization of aeolian landscapes, and a mechanism for large-scale excavation. Wind excavation of Gale Crater to form the 5 km high Mount Sharp would require removal of 6.4 x 104 km3 of sediment. Imagery in Gale Crater from satellites and the Mars Science Laboratory rover Curiosity shows a surface characterized by first-cycle aeolian erosion of bedrock. The overall landscape is interpreted to represent stages in a cycle of aeolian deflation and excavation, enhanced by physical weathering (e.g., thermal fracturing, cratering). Initial wind erosion of bedrock is enhanced along fractures, producing retreating scarps. Underlying less resistant layers then erode faster than the armoring cap rock, increasing relief in scarps to form retreating mesas. As scarp retreat continues, boulders from the armoring cap unit break away and cover the hillslopes of less resistant material below the scarps. Eventually all material from the capping unit is eroded away and a boulder-capped hill remains. Winnowing of fine material flattens hillslope topography, leaving behind a desert pavement. Over long enough time, this pavement is breached and the cycle begins anew. This cycle of landscape denudation by the wind is similar to that of water, but lacks characteristic subaqueous features such as dendritic drainage networks.

  10. Aeolian sedimentary processes at the Bagnold Dunes, Mars: Implications for modern dune dynamics and sedimentary structures in the aeolian stratigraphic record of Mars

    NASA Astrophysics Data System (ADS)

    Ewing, Ryan C.; Bridges, Nathan T.; Sullivan, Rob; Lapotre, Mathieu G. A.; Fischer, Woodward W.; Lamb, Mike P.; Rubin, David M.; Lewis, Kevin W.; Gupta, Sanjeev

    2016-04-01

    Wind-blown sand dunes are ubiquitous on the surface of Mars and are a recognized component of the martian stratigraphic record. Our current knowledge of the aeolian sedimentary processes that determine dune morphology, drive dune dynamics, and create aeolian cross-stratification are based upon orbital studies of ripple and dune morphodynamics, rover observations of stratification on Mars, Earth analogs, and experimental and theoretical studies of sand movement under Martian conditions. In-situ observations of sand dunes (informally called the Bagnold Dunes) by Curiosity Rover in Gale Crater, Mars provide the first opportunity to make observations of dunes from the grain-to-dune scale thereby filling the gap in knowledge between theory and orbital observations and refining our understanding of the martian aeolian stratigraphic record. We use the suite of cameras on Curiosity, including Navigation Camera (Navcam), Mast Camera (Mastcam) and Mars Hand Lens Imager (MAHLI), to make observations of the Bagnold Dunes. Measurements of sedimentary structures are made where stereo images are available. Observations indicate that structures generated by gravity-driven processes on the dune lee slopes, such as grainflow and grainfall, are similar to the suite of aeolian sedimentary structures observed on Earth and should be present and recognizable in Mars' aeolian stratigraphic record. Structures formed by traction-driven processes deviate significantly from those found on Earth. The dune hosts centimeter-scale wind ripples and large, meter-scale ripples, which are not found on Earth. The large ripples migrate across the depositional, lee slopes of the dune, which implies that these structures should be present in Mars' stratigraphic record and may appear similar to compound-dune stratification.The Mars Science Laboratory Curiosity Rover Team is acknowledged for their support of this work.

  11. The dynamic monitoring of aeolian desertification land distribution and its response to climate change in northern China

    NASA Astrophysics Data System (ADS)

    Feng, Lili; Jia, Zhiqing; Li, Qingxue

    2016-12-01

    Aeolian desertification is poorly understood despite its importance for indicating environment change. Here we exploit Gaofen-1(GF-1) and Moderate Resolution Imaging Spectroradiometer (MODIS) data to develop a quick and efficient method for large scale aeolian desertification dynamic monitoring in northern China. This method, which is based on Normalized Difference Desertification Index (NDDI) calculated by band1 & band2 of MODIS reflectance data (MODIS09A1). Then we analyze spatial-temporal change of aeolian desertification area and detect its possible influencing factors, such as precipitation, temperature, wind speed and population by Convergent Cross Mapping (CCM) model. It suggests that aeolian desertification area with population indicates feedback (bi-directional causality) between the two variables (P < 0.05), but forcing of aeolian desertification area by population is weak. Meanwhile, we find aeolian desertification area is significantly affected by temperature, as expected. However, there is no obvious forcing for the aeolian desertification area and precipitation. Aeolian desertification area with wind speed indicates feedback (bi-directional causality) between the two variables with significant signal (P < 0.01). We infer that aeolian desertification is greatly affected by natural factors compared with anthropogenic factors. For the desertification in China, we are greatly convinced that desertification prevention is better than control.

  12. The dynamic monitoring of aeolian desertification land distribution and its response to climate change in northern China

    PubMed Central

    Feng, Lili; Jia, Zhiqing; Li, Qingxue

    2016-01-01

    Aeolian desertification is poorly understood despite its importance for indicating environment change. Here we exploit Gaofen-1(GF-1) and Moderate Resolution Imaging Spectroradiometer (MODIS) data to develop a quick and efficient method for large scale aeolian desertification dynamic monitoring in northern China. This method, which is based on Normalized Difference Desertification Index (NDDI) calculated by band1 & band2 of MODIS reflectance data (MODIS09A1). Then we analyze spatial-temporal change of aeolian desertification area and detect its possible influencing factors, such as precipitation, temperature, wind speed and population by Convergent Cross Mapping (CCM) model. It suggests that aeolian desertification area with population indicates feedback (bi-directional causality) between the two variables (P < 0.05), but forcing of aeolian desertification area by population is weak. Meanwhile, we find aeolian desertification area is significantly affected by temperature, as expected. However, there is no obvious forcing for the aeolian desertification area and precipitation. Aeolian desertification area with wind speed indicates feedback (bi-directional causality) between the two variables with significant signal (P < 0.01). We infer that aeolian desertification is greatly affected by natural factors compared with anthropogenic factors. For the desertification in China, we are greatly convinced that desertification prevention is better than control. PMID:28004798

  13. Atmospheric tar balls from biomass burning in Mexico

    NASA Astrophysics Data System (ADS)

    Adachi, K.; Buseck, P. R.

    2009-12-01

    Tar balls are spherical, organic aerosol particles that result from biofuel or biomass burning. They absorb sunlight and cause warming of the atmosphere. Although distinctive when viewed with a transmission electron microscope (TEM) because of their spherical shape, much remains to be determined about details of their compositions, occurrences, and generation. Here we aim to characterize the occurrences of tar balls using individual-particle analyses with a TEM and to study their formation in young biomass-burning smoke. The samples were collected using the U.S. Forest Service Twin Otter aircraft during the MILAGRO (Megacity Initiative: Local and Global Research Observations) campaign conducted in March 2006. We analyzed 84 TEM grid samples from ~30 biomass-burning events near Mexico City and over Yucatan. Sixty samples were from young smoke (less than an hour old), and others were from haze that mainly occurred from biomass burning. Tar balls have neither an evident nucleus nor are they normally attached to other particles. They are almost perfectly spherical on TEM grids, indicating that they were solid when collected. It appears as if tar balls consist of lower volatility organic matter than many other organic aerosol particles. On average, 9% by number of biomass-burning aerosol particles were tar balls in samples collected between a few minutes to an hour after emission. On the other hand, samples collected within a few minutes after emission included few or no tar balls. The occurrences and abundances of atmospheric tar balls are important when evaluating the effects of smoke on local and regional climate.

  14. Atmospheric Tar Balls: Particles from Biomass and Biofuel Burning

    NASA Technical Reports Server (NTRS)

    Posfai, Mihaly; Gelencser, Andras; Simonics, Renata; Arato, Krisztina; Li, Jia; Hobbs, Peter V.; Buseck, Peter R.

    2004-01-01

    Tar balls are amorphous, carbonaceous spherules that occur in the tropospheric aerosol as a result of biomass and biofuel burning. They form a distinct group of particles with diameters typically between 30 and 500 nm and readily identifiable with electron microscopy. Their lack of a turbostratic microstructure distinguishes them from soot, and their morphology and composition (approximately 90 mol% carbon) renders them distinct from other carbonaceous particles. Tar balls are particularly abundant in slightly aged (minutes to hours old) biomass smoke, indicating that they likely form by gas-to-particle conversion within smoke plumes. The material of tar balls is initially hygroscopic; however, the particles become largely insoluble as a result of free radical polymerization of their organic molecules. Consequently, tar balls are primarily externally mixed with other particle types, and they do not appreciably increase in size during aging. When tar balls coagulate with water-bearing particles, their material may partly dissolve and no longer be recognizable as distinct particles. Tar balls may contain organic compounds that absorb sunlight. They are an important, previously unrecognized type of carbonaceous (organic) atmospheric particle.

  15. Linking fluvial and aeolian morphodynamics in the Grand Canyon, USA

    USGS Publications Warehouse

    Kasprak, Alan; Bangen, Sara G.; Buscombe, Daniel; Caster, Joshua; East, Amy; Grams, Paul E.; Sankey, Joel B.

    2017-01-01

    In river valleys, fluvial and upland landscapes are intrinsically linked through sediment exchange between the active channel, near-channel fluvial deposits, and higher elevation upland deposits. During floods, sediment is transferred from channels to low-elevation nearchannel deposits [Schmidt and Rubin, 1995]. Particularly in dryland river valleys, subsequent aeolian reworking of these flood deposits redistributes sediment to higher elevation upland sites, thus maintaining naturallyoccurring aeolian landscapes [Draut, 2012].

  16. Tar, nicotine, and carbon monoxide yields of some Nigerian cigarettes.

    PubMed Central

    Awotedu, A A; Higenbottam, T W; Onadeko, B O

    1983-01-01

    Fourteen cigarette brands manufactured in Nigeria in 1981 were analysed to determine the tar, nicotine, and carbon monoxide yields. Five of the brands belonged to the high and middle to high tar category (greater than 22 mg/cigarette) and nine to the middle tar (17-22 mg/cigarette) category. None of the cigarettes was in the low to middle and low tar (less than 17 mg/cigarette) category. The nicotine and carbon monoxide yields were similar to those of European cigarettes. Tobacco companies need to manufacture low tar cigarettes in the Third World as is the practice in the economically developed parts of the world. PMID:6619721

  17. Method and apparatus for hydrocarbon recovery from tar sands

    DOEpatents

    Westhoff, J.D.; Harak, A.E.

    1988-05-04

    A method and apparatus for utilizing tar sands having a broad range of bitumen content is disclosed. More particularly, tar sands are pyrolyzed in a cyclone retort with high temperature gases recycled from the cyclone retort to produce oil and hydrocarbon products. The spent tar sands are then burned at 2000/degree/F in a burner to remove residual char and produce a solid waste that is easily disposable. The process and apparatus have the advantages of being able to utilize tar sands having a broad range of bitumen content and the advantage of producing product gases that are free from combustion gases and thereby have a higher heating value. Another important advantage is rapid pyrolysis of the tar sands in the cyclone so as to effectively utilize smaller sized reactor vessels for reducing capitol and operating costs. 1 fig., 1 tab.

  18. Method and apparatus for hydrocarbon recovery from tar sands

    DOEpatents

    Westhoff, James D.; Harak, Arnold E.

    1989-01-01

    A method and apparatus for utilizing tar sands having a broad range of bitumen content is disclosed. More particularly, tar sands are pyrolyzed in a cyclone retort with high temperature gases recycled from the cyclone retort to produce oil and hydrocarbon products. The spent tar sands are then burned at 2000.degree. F. in a burner to remove residual char and produce a solid waste that is easily disposable. The process and apparatus have the advantages of being able to utilize tar sands having a broad range of bitumen content and the advantage of producing product gases that are free from combustion gases and thereby have a higher heating value. Another important advantage is rapid pyrolysis of the tar sands in the cyclone so as to effectively utilize smaller sized reactor vessels for reducing capitol and operating costs.

  19. Aeolian process of the dried-up riverbeds of the Hexi Corridor, China: a wind tunnel experiment.

    PubMed

    Zhang, Caixia; Wang, Xunming; Dong, Zhibao; Hua, Ting

    2017-08-01

    Wind tunnel studies, which remain limited, are an important tool to understand the aeolian processes of dried-up riverbeds. The particle size, chemical composition, and the mineral contents of sediments arising from the dried river beds are poorly understood. Dried-up riverbeds cover a wide area in the Hexi Corridor, China, and comprise a complex synthesis of different land surfaces, including aeolian deposits, pavement surfaces, and Takyr crust. The results of the present wind tunnel experiment suggest that aeolian transport from the dried-up riverbeds of the Hexi Corridor ranges from 0 to 177.04 g/m 2 /min and that dry riverbeds could be one of the main sources of dust emissions in this region. As soon as the wind velocity reaches 16 m/s and assuming that there are abundant source materials available, aeolian transport intensity increases rapidly. The dried-up riverbed sediment and the associated aeolian transported material were composed mainly of fine and medium sands. However, the transported samples were coarser than the bed samples, because of the sorting effect of the aeolian processes on the sediment. The aeolian processes also led to regional elemental migration and mineral composition variations.

  20. Aeolian Landscape Change in West Greenland

    NASA Astrophysics Data System (ADS)

    Heindel, Ruth Chaves

    In the Arctic, aeolian processes can be important drivers of landscape change. Soil deflation, the removal of fine-grained sediment by wind, is one aeolian process that has had a profound impact in the Arctic. While soil deflation has been well studied in Iceland, our understanding of aeolian processes across the rest of the Arctic remains limited. Kangerlussuaq, West Greenland, provides an opportunity to study the mechanisms and impacts of soil deflation without direct anthropogenic influence. In Kangerlussuaq, strong katabatic winds have resulted in distinct erosional landforms, here referred to as deflation patches, that are largely devoid of vascular plants and are dominated by biological soil crusts. This dissertation considers the geomorphic and ecological impacts of soil deflation through an interdisciplinary framework. I show that deflation patches are a critical component of the Kangerlussuaq ecosystem, accounting for 22% of the terrestrial landscape and impacting vegetation dynamics by providing habitat for graminoid, herbaceous, and lichen species. Deflation patches formed roughly 230-800 years ago, during a period of cold, dry, and windy climate conditions. Deflation patches expand across the landscape when the active margin, or scarp, becomes undercut and collapses. I estimate that rates of patch expansion are roughly 2.5 cm yr-1, and that geomorphic change can be detected even over the short time period of two years. I suggest that an erosional threshold exists because climate conditions required for initial deflation-patch formation are harsher than those required for continued patch expansion. The future trajectory of deflation patches depends on the role of the biological soil crust as either a successional facilitator or a long-term landscape cover, as well as future climate conditions. While the biological soil crusts slightly enrich soil fertility over time, they decrease soil moisture and create an impenetrable soil surface, which may inhibit

  1. Ground robotic measurement of aeolian processes

    USDA-ARS?s Scientific Manuscript database

    Models of aeolian processes rely on accurate measurements of the rates of sediment transport by wind, and careful evaluation of the environmental controls of these processes. Existing field approaches typically require intensive, event-based experiments involving dense arrays of instruments. These d...

  2. VAPOR PRESSURES AND HEATS OF VAPORIZATION OF PRIMARY COAL TARS

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

    Eric M. Suuberg; Vahur Oja

    1997-07-01

    This project had as its main focus the determination of vapor pressures of coal pyrolysis tars. It involved performing measurements of these vapor pressures and from them, developing vapor pressure correlations suitable for use in advanced pyrolysis models (those models which explicitly account for mass transport limitations). This report is divided into five main chapters. Each chapter is a relatively stand-alone section. Chapter A reviews the general nature of coal tars and gives a summary of existing vapor pressure correlations for coal tars and model compounds. Chapter B summarizes the main experimental approaches for coal tar preparation and characterization whichmore » have been used throughout the project. Chapter C is concerned with the selection of the model compounds for coal pyrolysis tars and reviews the data available to us on the vapor pressures of high boiling point aromatic compounds. This chapter also deals with the question of identifying factors that govern the vapor pressures of coal tar model materials and their mixtures. Chapter D covers the vapor pressures and heats of vaporization of primary cellulose tars. Chapter E discusses the results of the main focus of this study. In summary, this work provides improved understanding of the volatility of coal and cellulose pyrolysis tars. It has resulted in new experimentally verified vapor pressure correlations for use in pyrolysis models. Further research on this topic should aim at developing general vapor pressure correlations for all coal tars, based on their molecular weight together with certain specific chemical characteristics i.e. hydroxyl group content.« less

  3. Treating tar sands formations with dolomite

    DOEpatents

    Vinegar, Harold J.; Karanikas, John Michael

    2010-06-08

    Methods for treating a tar sands formation are described herein. The tar sands formation may include dolomite and hydrocarbons. Methods may include providing heat at less than the decomposition temperature of dolomite from one or more heaters to at least a portion of the formation. At least some of the hydrocarbon fluids are mobilized in the formation. At least some of the hydrocarbon fluids may be produced from the formation.

  4. Ultrasound assisted, thermally activated persulfate oxidation of coal tar DNAPLs.

    PubMed

    Peng, Libin; Wang, Li; Hu, Xingting; Wu, Peihui; Wang, Xueqing; Huang, Chumei; Wang, Xiangyang; Deng, Dayi

    2016-11-15

    The feasibility of ultrasound assisted, thermally activated persulfate for effective oxidation of twenty 2-6 ringed coal tar PAHs in a biphasic tar/water system and a triphasic tar/soil/water system were investigated and established. The results indicate that ultrasonic assistance, persulfate and elevated reaction temperature are all required to achieve effective oxidation of coal tar PAHs, while the heating needed can be provided by ultrasonic induced heating as well. Further kinetic analysis reveals that the oxidation of individual PAH in the biphasic tar/water system follows the first-order kinetics, and individual PAH oxidation rate is primary determined by the mass transfer coefficients, tar/water interfacial areas, the aqueous solubility of individual PAH and its concentration in coal tar. Based on the kinetic analysis and experimental results, the contributions of ultrasound, persulfate and elevated reaction temperature to PAHs oxidation were characterized, and the effects of ultrasonic intensity and oxidant dosage on PAHs oxidation efficiency were investigated. In addition, the results indicate that individual PAH degradability is closely related to its reactivity as well, and the high reactivity of 4-6 ringed PAHs substantially improves their degradability. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Aeolian and fluvial processes in dryland regions: the need for integrated studies

    USGS Publications Warehouse

    Belnap, Jayne; Munson, Seth M.; Field, Jason P.

    2011-01-01

    Aeolian and fluvial processes play a fundamental role in dryland regions of the world and have important environmental and ecological consequences from local to global scales. Although both processes operate over similar spatial and temporal scales and are likely strongly coupled in many dryland systems, aeolian and fluvial processes have traditionally been studied separately, making it difficult to assess their relative importance in drylands, as well as their potential for synergistic interaction. Land degradation by accelerated wind and water erosion is a major problem throughout the world's drylands, and although recent studies suggest that these processes likely interact across broad spatial and temporal scales to amplify the transport of soil resources from and within drylands, many researchers and land managers continue to view them as separate and unrelated processes. Here, we illustrate how aeolian and fluvial sediment transport is coupled at multiple spatial and temporal scales and highlight the need for these interrelated processes to be studied from a more integrated perspective that crosses traditional disciplinary boundaries. Special attention is given to how the growing threat of climate change and land-use disturbance will influence linkages between aeolian and fluvial processes in the future. We also present emerging directions for interdisciplinary needs within the aeolian and fluvial research communities that call for better integration across a broad range of traditional disciplines such as ecology, biogeochemistry, agronomy, and soil conservation.

  6. Fractal-like Tar Ball Aggregates from Wildfire Smoke

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

    Girotto, Giulia; China, Swarup; Bhandari, Janarjan

    Tar balls are atmospheric particles abundant in slightly aged biomass burning smoke and have a significant, but highly uncertain, role on Earth's radiative balance. Tar balls are typically detected using electron microscopy; they are resistant to the electron beam, and generally, they are observed as individual spheres. Here, we report new observations of a significant fraction of tar ball aggregates (~27% by number) from samples collected in a plume of the Whitewater-Baldy Complex fire in New Mexico. The structure of these aggregates is fractal-like and follows a scale invariant power law similar to that of soot particles, despite the considerablymore » larger size and smaller number of monomers. We also present observations of tar ball aggregates from four other geographical locations, including from a remote high elevation site in the North Atlantic Ocean. Aggregation affects the particle optical properties and therefore, their climatic impact. We performed numerical simulations based on the observed morphology and estimated the effects of aggregation on the tar balls optical properties. We find that aggregation can enhance single scattering albedo by up to 41%.« less

  7. Study on tar generated from downdraft gasification of oil palm fronds.

    PubMed

    Atnaw, Samson Mekbib; Kueh, Soo Chuan; Sulaiman, Shaharin Anwar

    2014-01-01

    One of the most challenging issues concerning the gasification of oil palm fronds (OPF) is the presence of tar and particulates formed during the process considering its high volatile matter content. In this study, a tar sampling train custom built based on standard tar sampling protocols was used to quantify the gravimetric concentration of tar (g/Nm3) in syngas produced from downdraft gasification of OPF. The amount of char, ash, and solid tar produced from the gasification process was measured in order to account for the mass and carbon conversion efficiency. Elemental analysis of the char and solid tar samples was done using ultimate analysis machine, while the relative concentration of the different compounds in the liquid tar was determined making use of a liquid gas chromatography (GC) unit. Average tar concentration of 4.928 g/Nm3 and 1.923 g/Nm3 was obtained for raw gas and cleaned gas samples, respectively. Tar concentration in the raw gas sample was found to be higher compared to results for other biomass materials, which could be attributed to the higher volatile matter percentage of OPF. Average cleaning efficiency of 61% which is comparable to that of sand bed filter and venturi scrubber cleaning systems reported in the literature was obtained for the cleaning system proposed in the current study.

  8. Study on Tar Generated from Downdraft Gasification of Oil Palm Fronds

    PubMed Central

    Atnaw, Samson Mekbib; Kueh, Soo Chuan; Sulaiman, Shaharin Anwar

    2014-01-01

    One of the most challenging issues concerning the gasification of oil palm fronds (OPF) is the presence of tar and particulates formed during the process considering its high volatile matter content. In this study, a tar sampling train custom built based on standard tar sampling protocols was used to quantify the gravimetric concentration of tar (g/Nm3) in syngas produced from downdraft gasification of OPF. The amount of char, ash, and solid tar produced from the gasification process was measured in order to account for the mass and carbon conversion efficiency. Elemental analysis of the char and solid tar samples was done using ultimate analysis machine, while the relative concentration of the different compounds in the liquid tar was determined making use of a liquid gas chromatography (GC) unit. Average tar concentration of 4.928 g/Nm3 and 1.923 g/Nm3 was obtained for raw gas and cleaned gas samples, respectively. Tar concentration in the raw gas sample was found to be higher compared to results for other biomass materials, which could be attributed to the higher volatile matter percentage of OPF. Average cleaning efficiency of 61% which is comparable to that of sand bed filter and venturi scrubber cleaning systems reported in the literature was obtained for the cleaning system proposed in the current study. PMID:24526899

  9. Long-term dynamic characterization of aeolian desertification in northwest Shanxi, China.

    PubMed

    Xue, Zhanjin; Qin, Zuodong; Cheng, Fangqin; Ding, Guangwei; Li, Hongjian

    2017-07-01

    Northwest Shanxi is located on the farming-pastoral ecotone of northern China, where aeolian desertification is one of the most serious environmental and socioeconomic issues. The remote sensing image and geostatistical approach were implemented to estimate aeolian desertified land (ADL) dynamic variations from 1975 to 2015. Results showed that the ADL covered 11,685.21 km 2 (82.29%) of the study area in 2015, the majority of which was classified as a light or moderate degree. The area of ADL gradually expanded at an increasing rate of 87.37 km 2 a -1 during the 1975-2000 periods. More specifically, the area of ADL has increased by 1259.23 km 2 from 1975 to 1990 and by 924.96 km 2 from 1990 to 2000, respectively. In contrast, spatial transfer of ADL areas has dwindled by 2365.85 km 2 with a net decrease of 157.72 km 2 a -1 , and the mitigated areas of aeolian desertification were 10,602.24 km 2 between 2000 and 2015. During the past 40 years, the gravity center of ADL migrated to southeast until 2000 and moved northwest in 2000-2015. From 1975 to 2000, the migration distance of severe ADL was the largest, migrated toward the northwest by 19.03 km in 1975-1990 and by 20.16 km in 1990-2000, respectively. From 2000 to 2015, the migration distance of light ADL was the largest, 27.54 km migrated to the northwest. Aeolian desertification rapidly expanded from 1975 to 2000 under the combination of climate change and intensive human activities. Since the year of 2000, ecological engineering strategy initiated by the governments has been the dominant contributor to the aeolian desertification severity reversal. Aeolian desertification prevention is a complicated process. Both the central and local government should play a critical role in the rehabilitation of ADL in the long term.

  10. NASA's Planetary Aeolian Laboratory: Status and Update

    NASA Astrophysics Data System (ADS)

    Williams, D. A.; Smith, J. K.

    2017-05-01

    This presentation provides a status update on the operational capabilities and funding plans by NASA for the Planetary Aeolian Laboratory located at NASA Ames Research Center, including details for those proposing future wind tunnel experiments.

  11. Sediment connectivity at source-bordering aeolian dunefields along the Colorado River in the Grand Canyon, USA

    NASA Astrophysics Data System (ADS)

    Sankey, Joel; Kasprak, Alan; Caster, Joshua; East, Amy; Fairley, Helen

    2017-04-01

    Aeolian dunefields that are primarily built and maintained with river-derived sediment are found in many river valleys throughout the world and are impacted by changes in climate, land use, and river regulation. Quantifying the dynamic response of these aeolian dunefields to alterations in river flow is especially difficult given the highly correlated nature of the interacting geomorphic and sediment transport processes that drive their formation and maintenance. We characterize the effects of controlled river floods on changes in sediment connectivity at source-bordering aeolian dunefields in the Grand Canyon, USA. Controlled floods from the Glen Canyon Dam are used to build sandbars along the Colorado River in Grand Canyon which provide the main sediment source for aeolian dunefields. Aeolian dunefields are a primary resource of concern for land managers in the Grand Canyon because they often contain buried archaeological features. To characterize dunefield response to controlled floods, we use a novel, automated approach for the mechanistic segregation of geomorphic change to discern the geomorphic processes responsible for driving topographic change in very high resolution digital elevation models-of-difference (DODs) that span multiple, consecutive controlled river floods at source-bordering dunefields. We subsequently compare the results of mechanistic segregation with modelled estimates of aeolian dunefield evolution in order to understand how dunefields respond to contemporary, anthropogenically-driven variability in sediment supply and connectivity. These methods provide a rapid technique for sediment budgeting and enable the inference of spatial and temporal patterns in sediment flux between the fluvial and aeolian domains. We anticipate that this approach will be adaptable to other river valleys where the interactions of aeolian, fluvial, and hillslope processes drive sediment connectivity for the maintenance of source-bordering aeolian dunefields.

  12. Sydney Tar Ponds Remediation: Experience to China

    ERIC Educational Resources Information Center

    Liu, Fan; Bryson, Ken A.

    2009-01-01

    The infamous "Sydney Tar Ponds" are well known as one of the largest toxic waste sites of Canada, due to almost 100 years of steelmaking in Sydney, a once beautiful and peaceful city located on the east side of Cape Breton Island, Nova Scotia. This article begins with a contextual overview of the Tar Ponds issue including a brief…

  13. Aeolian dust in Colorado Plateau soils: Nutrient inputs and recent change in source

    PubMed Central

    Reynolds, Richard; Belnap, Jayne; Reheis, Marith; Lamothe, Paul; Luiszer, Fred

    2001-01-01

    Aeolian dust (windblown silt and clay) is an important component in arid-land ecosystems because it may contribute to soil formation and furnish essential nutrients. Few geologic surfaces, however, have been characterized with respect to dust-accumulation history and resultant nutrient enrichment. We have developed a combination of methods to identify the presence of aeolian dust in arid regions and to evaluate the roles of this dust in ecosystem processes. Unconsolidated sandy sediment on isolated surfaces in the Canyonlands region of the Colorado Plateau differs greatly in mineralogical and chemical composition from associated bedrock, mainly aeolian sandstone. Detrital magnetite in the surficial deposits produces moderately high values of magnetic susceptibility, but magnetite is absent in nearby bedrock. A component of the surficial deposits must be aeolian to account for the abundance of magnetite, which formed originally in far-distant igneous rocks. Particle-size analysis suggests that the aeolian dust component is typically as much as 20–30%. Dust inputs have enriched the sediments in many elements, including P, Mg, Na, K, and Mo, as well as Ca, at sites where bedrock lacks calcite cement. Soil-surface biologic crusts are effective dust traps that apparently record a change in dust sources over the past several decades. Some of the recently fallen dust may result from human disturbance of land surfaces that are far from the Canyonlands, such as the Mojave Desert. Some land-use practices in the study area have the potential to deplete soil fertility by means of wind-erosion removal of aeolian silt. PMID:11390965

  14. Aeolian dust in Colorado Plateau soils: Nutrient inputs and recent change in source

    USGS Publications Warehouse

    Reynolds, R.; Belnap, Jayne; Lamothe, Paul; Luiszer, Fred

    2001-01-01

    Aeolian dust (windblown silt and clay) is an important component in arid-land ecosystems because it may contribute to soil formation and furnish essential nutrients. Few geologic surfaces, however, have been characterized with respect to dust-accumulation history and resultant nutrient enrichment. We have developed a combination of methods to identify the presence of aeolian dust in arid regions and to evaluate the roles of this dust in ecosystem processes. Unconsolidated sandy sediment on isolated surfaces in the Canyonlands region of the Colorado Plateau differs greatly in mineralogical and chemical composition from associated bedrock, mainly aeolian sandstone. Detrital magnetite in the surficial deposits produces moderately high values of magnetic susceptibility, but magnetite is absent in nearby bedrock. A component of the surficial deposits must be aeolian to account for the abundance of magnetite, which formed originally in far-distant igneous rocks. Particle-size analysis suggests that the aeolian dust component is typically as much as 20a??30%. Dust inputs have enriched the sediments in many elements, including P, Mg, Na, K, and Mo, as well as Ca, at sites where bedrock lacks calcite cement. Soil-surface biologic crusts are effective dust traps that apparently record a change in dust sources over the past several decades. Some of the recently fallen dust may result from human disturbance of land surfaces that are far from the Canyonlands, such as the Mojave Desert. Some land-use practices in the study area have the potential to deplete soil fertility by means of wind-erosion removal of aeolian silt.

  15. Gully annealing by fluvially-sourced Aeolian sand: remote sensing investigations of connectivity along the Fluvial-Aeolian-hillslope continuum on the Colorado River

    USGS Publications Warehouse

    Sankey, Joel B.; East, Amy E.; Collins, Brian D.; Caster, Joshua J.

    2015-01-01

    Processes contributing to development of ephemeral gully channels are of great importance to landscapes worldwide, and particularly in dryland regions where soil loss and land degradation from gully erosion pose long-term, land-management problems. Whereas gully formation has been relatively well studied, much less is known of the processes that anneal gullies and impede their growth. This work investigates gully annealing by aeolian sediment, along the Colorado River downstream of Glen Canyon Dam in Glen, Marble, and Grand Canyons, Arizona, USA (Figure 1). In this segment of the Colorado River, gully erosion potentially affects the stability and preservation of archaeological sites that are located within valley margins. Gully erosion occurs as a function of ephemeral, rainfall-induced overland flow associated with intense episodes of seasonal precipitation. Measurements of sediment transport and topographic change have demonstrated that fluvial sand in some locations is transported inland and upslope by aeolian processes to areas affected by gully erosion, and aeolian sediment activity can be locally effective at counteracting gully erosion (Draut, 2012; Collins and others, 2009, 2012; Sankey and Draut, 2014). The degree to which specific locations are affected by upslope wind redistribution of sand from active channel sandbars to higher elevation valley margins is termed “connectivity”. Connectivity is controlled spatially throughout the river by (1) the presence of upwind sources of fluvial sand within the contemporary active river channel (e.g., sandbars), and (2) bio-physical barriers that include vegetation and topography that might impede aeolian sediment transport. The primary hypothesis of this work is that high degrees of connectivity lead to less gullying potential.

  16. Aeolian Processes and Features on Venus

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Bender, Kelly C.; Saunders, Stephen; Schubert, Gerald; Weitz, Catherine M.

    1997-01-01

    Aeolian features on Venus include dune fields, eroded hills (yardangs), wind streaks, (miniature dunes of 10 to 30 cm wavelength). Although and possibly microdunes (in repetitive imaging by Magellan did show changes in the appearance of the surface, these changes are attributed to radar artifacts as a consequence of look direction rather than to physical changes of the surface. Nonetheless, measurements of wind speeds near the surface of Venus and wind tunnel simulations suggest that aeolian processes could be currently active on Venus. Study of radar images of terrestrial analogs shows that radar wavelength, polarization, and viewing geometry, including look direction and incidence angle, all influence the detection of dunes, yardangs, and wind streaks. For best detection, dune crests and yardangs should be oriented perpendicular to look direction. Longer wavelength systems can penetrate sand sheets a meter or more thick, rendering them invisible, especially in arid regions. For wind streaks to be visible, there must be a contrast in surface properties between the streak and the background on which it occurs. Nonetheless, more than 6000 aeolian features have been found on Magellan images of Venus, the most common of which are various wind streaks. Mapping wind streak orientations enables near-surface wind patterns to be inferred for the time of their formation. Type P streaks are associated with parabolic ejecta crater deposits and are considered to have formed in association with the impact event. Most Type P streaks are oriented westward, indicative of the upper altitude superrotation winds of Venus. Non Type P streaks have occurrences and orientations consistent with Hadley circulation. Some streaks in the southern hemisphere are oriented to the northeast, suggesting a Coriolis effect.

  17. Application of Database Approaches to the Study of Earth's Aeolian Environments: Community Needs and Goals

    NASA Astrophysics Data System (ADS)

    Scuderi, Louis A.; Weissmann, Gary S.; Hartley, Adrian J.; Yang, Xiaoping; Lancaster, Nicholas

    2017-08-01

    Aeolian science is faced with significant challenges that impact its ability to benefit from recent advances in information technology. The discipline deals with high-end systems in the form of ground and satellite based sensors, computer modeling and simulation, and wind tunnel experiments. Aeolian scientists also collect field data manually with observational methods that may differ significantly between studies with little agreement on even basic morphometric parameters and terminology. Data produced from these studies, while forming the core of research papers and reports, is rarely available to the community at large. Recent advances are also superimposed on an underlying semantic structure that dates to the 1800's or earlier that is confusing, with ambiguously defined, and at times even contradictory, meanings. The aeolian "world-view" does not always fit within neat increments nor is defined by crisp objects. Instead change is continuous and features are fuzzy. Development of an ontological framework to guide spatiotemporal research is the fundamental starting point for organizing data in aeolian science. This requires a "rethinking" of how we define, collect, process, store and share data along with the development of a community-wide collaborative approach designed to bring the discipline into a data rich future. There is also a pressing need to develop efficient methods to integrate, analyze and manage spatial and temporal data and to promote data produced by aeolian scientists so it is available for preparing diagnostic studies, as input into a range of environmental models, and for advising national and international bodies that drive research agendas. This requires the establishment of working groups within the discipline to deal with content, format, processing pipelines, knowledge discovery tools and database access issues unique to aeolian science. Achieving this goal requires the development of comprehensive and highly-organized databases, tools

  18. Design and initial testing of a piezoelectric sensor to quantify aeolian sand transport

    NASA Astrophysics Data System (ADS)

    Raygosa-Barahona, Ruben; Ruiz-Martinez, Gabriel; Mariño-Tapia, Ismael; Heyser-Ojeda, Emilio

    2016-09-01

    This paper describes a sensor for measuring the mass flux of aeolian sand transport based on a low-cost piezo-electric transducer. The device is able to measure time series of aeolian sand transport. Maximum fluxes of 27 mg per second can be achieved. The design includes a sand trap, an electronic amplifier circuit and an embedded system for data collection. A field test was performed, where the basis for signal interpretation and the corresponding measurements of aeolian sand transport are presented. The sensor successfully measures fluxes driven by sea breezes of 10 ms-1, showing the importance of this process for dune-building in the region.

  19. Biodiversity impact of the aeolian periglacial geomorphologic evolution of the Fontainebleau Massif (France)

    NASA Astrophysics Data System (ADS)

    Thiry, M.; Liron, M. N.

    2009-04-01

    Landscape features The geomorphology of the Fontainebleau Massif is noteworthy for its spectacular narrow ridges, up to 10 km long and 0.5 km wide, armored by tightly cemented sandstone lenses and which overhang sandy depressions of about 50m. Denudation of the sandstone pans lead to a highly contrasted landscape, with sandstone ridges ("platières") towering sandy depressions ("vallées") and limestone plateaus ("monts"). This forms the geological frame of the spectacular sceneries of the Fontainebleau Massif (Thiry & Liron, 2007). Nevertheless, there is little know about the erosive processes that have built-up these landscapes. Periglacial processes, and among them aeolian ones, appear significant in the development of the Fontainebleau Massif physiography. The periglacial aeolian geomorphology Dunes and dune fields are known since long and cover about 15% to 25% of the Fontainebleau Massif. The aeolian dunes developed as well on the higher parts of the landscape, as well as in the lower parts of the landscape. The dunes are especially well developed in the whole eastern part of the massif, whereas the western part of the massif is almost devoid of dunes. Nevertheless, detailed mapping shows that dunes can locally be found in the western district, they are of limited extension, restricted to the east facing backslope of outliers. Loamy-sand covers the limestone plateaus of the "monts". The loam cover is of variable thickness: schematically thicker in the central part of the plateaus, where it my reach 3 m; elsewhere it may thin down to 0,20-0,30 m, especially at the plateau edges. Blowout hollows are "negative" morphologies from where the sand has been withdrawed. Often these blowouts are decametric sized and well-delimited structures. Others, more complex structures, are made up of several elongated hectometric hollows relaying each other from and which outline deflation corridor more than 1 km long. A characteristic feature of these blowout hollows is the

  20. 48 CFR Appendix to Part 1252 - Tar Matrix

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Tar Matrix Appendix to Part 1252 Federal Acquisition Regulations System DEPARTMENT OF TRANSPORTATION CLAUSES AND FORMS SOLICITATION PROVISIONS AND CONTRACT CLAUSES Pt. 1252, App. Appendix to Part 1252—Tar Matrix ER27DE05.000...

  1. Integrated Biomass Gasification with Catalytic Partial Oxidation for Selective Tar Conversion

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

    Zhang, Lingzhi; Wei, Wei; Manke, Jeff

    Biomass gasification is a flexible and efficient way of utilizing widely available domestic renewable resources. Syngas from biomass has the potential for biofuels production, which will enhance energy security and environmental benefits. Additionally, with the successful development of low Btu fuel engines (e.g. GE Jenbacher engines), syngas from biomass can be efficiently used for power/heat co-generation. However, biomass gasification has not been widely commercialized because of a number of technical/economic issues related to gasifier design and syngas cleanup. Biomass gasification, due to its scale limitation, cannot afford to use pure oxygen as the gasification agent that used in coal gasification.more » Because, it uses air instead of oxygen, the biomass gasification temperature is much lower than well-understood coal gasification. The low temperature leads to a lot of tar formation and the tar can gum up the downstream equipment. Thus, the biomass gasification tar removal is a critical technology challenge for all types of biomass gasifiers. This USDA/DOE funded program (award number: DE-FG36-O8GO18085) aims to develop an advanced catalytic tar conversion system that can economically and efficiently convert tar into useful light gases (such as syngas) for downstream fuel synthesis or power generation. This program has been executed by GE Global Research in Irvine, CA, in collaboration with Professor Lanny Schmidt's group at the University of Minnesota (UoMn). Biomass gasification produces a raw syngas stream containing H2, CO, CO2, H2O, CH4 and other hydrocarbons, tars, char, and ash. Tars are defined as organic compounds that are condensable at room temperature and are assumed to be largely aromatic. Downstream units in biomass gasification such as gas engine, turbine or fuel synthesis reactors require stringent control in syngas quality, especially tar content to avoid plugging (gum) of downstream equipment. Tar- and ash-free syngas streams are a

  2. A Fuzzy Cognitive Model of aeolian instability across the South Texas Sandsheet

    NASA Astrophysics Data System (ADS)

    Houser, C.; Bishop, M. P.; Barrineau, C. P.

    2014-12-01

    Characterization of aeolian systems is complicated by rapidly changing surface-process regimes, spatio-temporal scale dependencies, and subjective interpretation of imagery and spatial data. This paper describes the development and application of analytical reasoning to quantify instability of an aeolian environment using scale-dependent information coupled with conceptual knowledge of process and feedback mechanisms. Specifically, a simple Fuzzy Cognitive Model (FCM) for aeolian landscape instability was developed that represents conceptual knowledge of key biophysical processes and feedbacks. Model inputs include satellite-derived surface biophysical and geomorphometric parameters. FCMs are a knowledge-based Artificial Intelligence (AI) technique that merges fuzzy logic and neural computing in which knowledge or concepts are structured as a web of relationships that is similar to both human reasoning and the human decision-making process. Given simple process-form relationships, the analytical reasoning model is able to map the influence of land management practices and the geomorphology of the inherited surface on aeolian instability within the South Texas Sandsheet. Results suggest that FCMs can be used to formalize process-form relationships and information integration analogous to human cognition with future iterations accounting for the spatial interactions and temporal lags across the sand sheets.

  3. Mechanics of aeolian processes: Soil erosion and dust production

    NASA Technical Reports Server (NTRS)

    Mehrabadi, M. M.

    1989-01-01

    Aeolian (wind) processes occur as a result of atmosphere/land-surface system interactions. A thorough understanding of these processes and their physical/mechanical characterization on a global scale is essential to monitoring global change and, hence, is imperative to the fundamental goal of the Earth observing system (Eos) program. Soil erosion and dust production by wind are of consequence mainly in arid and semi arid regions which cover 36 percent of the Earth's land surface. Some recent models of dust production due to wind erosion of agricultural soils and the mechanics of wind erosion in deserts are reviewed and the difficulties of modeling the aeolian transport are discussed.

  4. Ecohydrological implications of aeolian sediment trapping by sparse vegetation in drylands

    USGS Publications Warehouse

    Gonzales, Howell B.; Ravi, Sujith; Li, Junran; Sankey, Joel B.

    2018-01-01

    Aeolian processes are important drivers of ecosystem dynamics in drylands, and important feedbacks exist among aeolian – hydrological processes and vegetation. The trapping of wind-borne sediments by vegetation may result in changes in soil properties beneath the vegetation, which, in turn, can alter hydrological and biogeochemical processes. Despite the relevance of aeolian transport to ecosystem dynamics, the interactions between aeolian transport and vegetation in shaping dryland landscapes where sediment distribution is altered by relatively rapid changes in vegetation composition such as shrub encroachment, is not well understood. Here, we used a computational fluid dynamics (CFD) modeling framework to investigate the sediment trapping efficiencies of vegetation canopies commonly found in a shrub-grass ecotone in the Chihuahuan Desert (New Mexico, USA) and related the results to spatial heterogeneity in soil texture and infiltration measured in the field. A CFD open-source software package was used to simulate aeolian sediment movement through three-dimensional architectural depictions of Creosote shrub (Larrea tridentata) and Black Grama grass (Bouteloua eriopoda) vegetation types. The vegetation structures were created using a computer-aided design software (Blender), with inherent canopy porosities, which were derived using LIDAR (Light Detection and Ranging) measurements of plant canopies. Results show that considerable heterogeneity in infiltration and soil grain size distribution exist between the microsites, with higher infiltration and coarser soil texture under shrubs. Numerical simulations also indicate that the differential trapping of canopies might contribute to the observed heterogeneity in soil texture. In the early stages of encroachment, the shrub canopies, by trapping coarser particles more efficiently, might maintain higher infiltration rates leading to faster development of the microsites (among other factors) with enhanced ecological

  5. Our evolving understanding of aeolian bedforms, based on observation of dunes on different worlds

    NASA Astrophysics Data System (ADS)

    Diniega, Serina; Kreslavsky, Mikhail; Radebaugh, Jani; Silvestro, Simone; Telfer, Matt; Tirsch, Daniela

    2017-06-01

    Dunes, dune fields, and ripples are unique and useful records of the interaction between wind and granular materials - finding such features on a planetary surface immediately suggests certain information about climate and surface conditions (at least during the dunes' formation and evolution). Additionally, studies of dune characteristics under non-Earth conditions allow for ;tests; of aeolian process models based primarily on observations of terrestrial features and dynamics, and refinement of the models to include consideration of a wider range of environmental and planetary conditions. To-date, the planetary aeolian community has found and studied dune fields on Mars, Venus, and the Saturnian moon Titan. Additionally, we have observed candidate ;aeolian bedforms; on Comet 67P/Churyumov-Gerasimenko, the Jovian moon Io, and - most recently - Pluto. In this paper, we hypothesize that the progression of investigations of aeolian bedforms and processes on a particular planetary body follows a consistent sequence - primarily set by the acquisition of data of particular types and resolutions, and by the maturation of knowledge about that planetary body. We define that sequence of generated knowledge and new questions (within seven investigation phases) and discuss examples from all of the studied bodies. The aim of such a sequence is to better define our past and current state of understanding about the aeolian bedforms of a particular body, to highlight the related assumptions that require re-analysis with data acquired during later investigations, and to use lessons learned from planetary and terrestrial aeolian studies to predict what types of investigations could be most fruitful in the future.

  6. Studies in Martian Aeolian Geology

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    2001-01-01

    This report gives the results from the investigation through March 15, 1999 for the first two years of the three year investigation (year 3 runs from March 1, 1999 to February 27, 2000). The investigation included three tasks, all involving windblown dust (particles a few micrometers in diameter) to simulate the aeolian regime on Mars. Experiments were conducted primarily in the Mars Surface Wind Tunnel (MARSWIT) at NASA-Ames Research Center.

  7. Aeolian Environments of Iceland

    NASA Astrophysics Data System (ADS)

    Arnalds, Olafur; Olafsson, Haraldur; Dagsson Waldhauserová, Pavla

    2017-04-01

    Iceland has the largest area of volcaniclastic sandy desert on Earth or 22,000 km2. The sand has been mostly produced by glacio-fluvial processes, leaving behind fine-grained unstable sediments which are later re-distributed by repeated aeolian events. Volcanic eruptions add to this pool of unstable sediments, often from subglacial eruptions. Icelandic desert surfaces are divided into sand fields, sandy lavas and sandy lag gravel, each with separate aeolian surface characteristics such as threshold velocities. Storms are frequent due to Iceland's location on the North Atlantic Storm track. Dry winds occur on the leeward sides of mountains and glaciers, in spite of the high moisture content of the Atlantic cyclones. Surface winds often move hundreds to more than 1000 kg m-1 per annum, and more than 10,000 kg m-1 have been measured in a single storm. Desertification occurs when aeolian processes push sand fronts and have thus destroyed many previously fully vegetated ecosystems since the time of the settlement of Iceland in the late ninth century. There are about 135 dust events per annum, ranging from minor storms to >300,000 t of dust emitted in single storms. Dust can be generated from all the major sandy areas of Iceland; however the amount of finer particles that become dust varies with the surfaces. There are areas that produce more dust by far compared to the general sandy deserts; they have therefore been termed "dust plume areas" or "dust hot-spots". They are characterized by repeated charging of fine sediments with a relatively high proportion of finer (silty) materials which, upon repeated wind erosion become sorted downwind from the sources with loss of silt (dust) and an increasing saltation component (sand). Dust production is on the order of 30-40 million tons annually, some travelling over 1000 km and deposited on land and sea. Dust deposited on deserts tends to be re-suspended during subsequent storms. High PM10 concentrations occur during major dust

  8. 29 CFR 1910.1002 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 6 2013-07-01 2013-07-01 false Coal tar pitch volatiles; interpretation of term. 1910.1002... Hazardous Substances § 1910.1002 Coal tar pitch volatiles; interpretation of term. As used in § 1910.1000 (Table Z-1), coal tar pitch volatiles include the fused polycyclic hydrocarbons which volatilize from the...

  9. 29 CFR 1910.1002 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 6 2010-07-01 2010-07-01 false Coal tar pitch volatiles; interpretation of term. 1910.1002... Hazardous Substances § 1910.1002 Coal tar pitch volatiles; interpretation of term. As used in § 1910.1000 (Table Z-1), coal tar pitch volatiles include the fused polycyclic hydrocarbons which volatilize from the...

  10. 29 CFR 1910.1002 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 6 2011-07-01 2011-07-01 false Coal tar pitch volatiles; interpretation of term. 1910.1002... Hazardous Substances § 1910.1002 Coal tar pitch volatiles; interpretation of term. As used in § 1910.1000 (Table Z-1), coal tar pitch volatiles include the fused polycyclic hydrocarbons which volatilize from the...

  11. 29 CFR 1910.1002 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 6 2012-07-01 2012-07-01 false Coal tar pitch volatiles; interpretation of term. 1910.1002... Hazardous Substances § 1910.1002 Coal tar pitch volatiles; interpretation of term. As used in § 1910.1000 (Table Z-1), coal tar pitch volatiles include the fused polycyclic hydrocarbons which volatilize from the...

  12. 29 CFR 1910.1002 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 6 2014-07-01 2013-07-01 true Coal tar pitch volatiles; interpretation of term. 1910.1002... Hazardous Substances § 1910.1002 Coal tar pitch volatiles; interpretation of term. As used in § 1910.1000 (Table Z-1), coal tar pitch volatiles include the fused polycyclic hydrocarbons which volatilize from the...

  13. Coal tar-containing asphalt - resource or hazardous waste?

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

    Andersson-Skold, Y.; Andersson, K.; Lind, B.

    2007-09-30

    Coal tar was used in Sweden for the production of asphalt and for the drenching of stabilization gravel until 1973. The tar has high concentrations of polycyclic aromatic hydrocarbons (PAH), some of which may be strongly carcinogenic. Approximately 20 million tonnes of tar-containing asphalt is present in the public roads in Sweden. Used asphalt from rebuilding can be classified as hazardous waste according to the Swedish Waste Act. The cost of treating the material removed as hazardous waste can be very high due to the large amount that has to be treated, and the total environmental benefit is unclear. Themore » transport of used asphalt to landfill or combustion will affect other environmental targets. The present project, based on three case studies of road projects in Sweden, evaluates the consequences of four scenarios for handling the material: reuse, landfill, biological treatment, and incineration. The results show that reuse of the coal tar-containing materials in new road construction is the most favorable alternative in terms of cost, material use, land use, energy consumption, and air emissions.« less

  14. The effects of sorting by aeolian processes on the geochemical characteristics of surface materials: a wind tunnel experiment

    NASA Astrophysics Data System (ADS)

    Wang, Xunming; Lang, Lili; Hua, Ting; Zhang, Caixia; Li, Hui

    2018-03-01

    The geochemical characteristics of aeolian and surface materials in potential source areas of dust are frequently employed in environmental reconstructions as proxies of past climate and as source tracers of aeolian sediments deposited in downwind areas. However, variations in the geochemical characteristics of these aeolian deposits that result from near-surface winds are currently poorly understood. In this study, we collected surface samples from the Ala Shan Plateau (a major potential dust source area in Central Asia) to determine the influence of aeolian processes on the geochemical characteristics of aeolian transported materials. Correlation analyses show that compared with surface materials, the elements in transported materials (e.g., Cu, As, Pb, Mn, Zn, Al, Ca, Fe, Ga, K, Mg, P, Rb, Co, Cr, Na, Nb, Si, and Zr) were subjected to significant sorting by aeolian processes, and the sorting also varied among different particle size fractions and elements. Variations in wind velocity were significantly correlated with the contents of Cr, Ga, Sr, Ca, Y, Nd, Zr, Nb, Ba, and Al, and with the Zr/Al, Zr/Rb, K/Ca, Sr/Ca, Rb/Sr, and Ca/Al ratios. Given the great variation in the geochemical characteristics of materials transported under different aeolian processes relative to those of the source materials, these results indicate that considerable uncertainty may be introduced to analyses by using surface materials to trace the potential source areas of aeolian deposits that accumulate in downwind areas.

  15. McLaughlin and Mars. [volcanic-aeolian hypotheses for Martian surface features

    NASA Technical Reports Server (NTRS)

    Veverka, J.; Sagan, C.

    1974-01-01

    McLaughlin formulated a novel explanation for the Martian albedo markings and their variations. This explanation, the volcanic-aeolian hypothesis, is one of the very few prespacecraft views of planet-wide phenomena on Mars which have stood the test of time. The distribution of albedo markings is considered along with secular changes on Mars and seasonal changes in region Syrtis Major. Mariner 9 has demonstrated that aeolian transport is the dominant factor in determining the distribution of albedo markings on Mars.

  16. Effects of aeolian erosion on microbial release from solids.

    NASA Technical Reports Server (NTRS)

    Gustan, E. A.; Olson, R. L.; Taylor, D. M.; Green, R. H.

    1972-01-01

    This study was initiated to determine the percentage of spores that would be expected to be released from the interior of solid materials by aeolian erosion on a planetary surface. Methyl methacrylate and Eccobond disks were fabricated so that each disk contained approximately 40,000 Bacillus subtilis var. niger spores. The disks were placed in a specially designed sandblasting device and eroded. Exposure periods of 0.5, 2 and 24 hours were investigated using filtered air to accelerate the sand. A series of tests was also conducted for a 0.5 hour period using carbon dioxide. Examination of the erosion products showed that less than 1% of the spores originally contained in the solids was released by aeolian erosion.

  17. Roughness configuration matters for aeolian sediment flux

    USDA-ARS?s Scientific Manuscript database

    The parameterisation of surface roughness effects on aeolian sediment transport is a key source of uncertainty in wind erosion models. Roughness effects are typically represented by bulk drag-partitioning schemes that scale the threshold friction velocity (u*t) for soil entrainment by the ratio of s...

  18. Observations of an aeolian landscape: From surface to orbit in Gale Crater

    NASA Astrophysics Data System (ADS)

    Day, Mackenzie; Kocurek, Gary

    2016-12-01

    Landscapes derived solely from aeolian processes are rare on Earth because of the dominance of subaqueous processes. In contrast, aeolian-derived landscapes should typify Mars because of the absence of liquid water, the long exposure times of surfaces, and the presence of wind as the default geomorphic agent. Using the full range of available orbital and Mars Science Laboratory rover Curiosity images, wind-formed features in Gale Crater were cataloged and analyzed in order to characterize the aeolian landscape and to derive the evolution of the crater wind regime over time. Inferred wind directions show a dominance of regional northerly winds over geologic time-scales, but a dominance of topography-driven katabatic winds in modern times. Landscapes in Gale Crater show a preponderance of aeolian features at all spatial scales. Interpreted processes forming these features include first-cycle aeolian abrasion of bedrock, pervasive deflation, organization of available sand into bedforms, abundant cratering, and gravity-driven wasting, all of which occur over a background of slow physical weathering. The observed landscapes are proposed to represent a spectrum of progressive surface denudation from fractured bedrock, to retreating bedrock-capped mesas, to remnant hills capped by bedrock rubble, to desert pavement plains. This model of landscape evolution provides the mechanism by which northerly winds acting over ∼3 Ga excavated tens of thousands of cubic kilometers of material from the once sediment-filled crater, thus carving the intra-crater moat and exhuming Mount Sharp (Aeolis Mons). The current crater surface is relatively sand-starved, indicating that potential sediment deflation from the crater is greater than sediment production, and that most exhumation of Mount Sharp occurred in the ancient geologic past.

  19. Transformation-associated recombination (TAR) cloning for genomics studies and synthetic biology

    PubMed Central

    Kouprina, Natalay; Larionov, Vladimir

    2016-01-01

    Transformation-associated recombination (TAR) cloning represents a unique tool for isolation and manipulation of large DNA molecules. The technique exploits a high level of homologous recombination in the yeast Sacharomyces cerevisiae. So far, TAR cloning is the only method available to selectively recover chromosomal segments up to 300 kb in length from complex and simple genomes. In addition, TAR cloning allows the assembly and cloning of entire microbe genomes up to several Mb as well as engineering of large metabolic pathways. In this review, we summarize applications of TAR cloning for functional/structural genomics and synthetic biology. PMID:27116033

  20. Aeolian processes over gravel beds: Field wind tunnel simulation and its application atop the Mogao Grottoes, China

    NASA Astrophysics Data System (ADS)

    Zhang, Weimin; Tan, Lihai; Zhang, Guobin; Qiu, Fei; Zhan, Hongtao

    2014-12-01

    The aeolian processes of erosion, transport and deposition are threatening the Mogao Grottoes, a world culture heritage site. A field wind tunnel experiment was conducted atop the Mogao Grottoes using weighing sensors to quantify aeolian processes over protective gravel beds. Results reveal that aeolian erosion and deposition over gravel beds are basically influenced by gravel coverage and wind speed. Erosion is a main aeolian process over gravel beds and its strength level is mainly determined by gravel coverage: strong (<30%), medium (30-50%) and slight (>50%). Aeolian deposition only occurs when gravel coverage is equal to or greater than 30% and wind speeds are between 8 and 12 m s-1, and this process continues until the occurrence of the equilibrium coverage. In addition, the change in conditions of external sand supply affects the transition between aeolian deposition and erosion over gravel beds, and the quantity of sand transport at the height of 0-24 mm is an important indicator of aeolian deposition and erosion over gravel beds. Our results also demonstrate that making the best use of wind regime atop the Mogao Grottoes and constructing an artificial gobi surface in staggered arrays, with 30% coverage and 30-mm-high gravels and in 40 mm spacing can trap westerly invading sand flow and enable the stronger easterly wind to return the deposited sand on the gravel surface back to the Mingsha Mountain so as to minimize the damage of the blown sand flux to the Mogao Grottoes.

  1. Coal tar induces AHR-dependent skin barrier repair in atopic dermatitis

    PubMed Central

    van den Bogaard, Ellen H.; Bergboer, Judith G.M.; Vonk-Bergers, Mieke; van Vlijmen-Willems, Ivonne M.J.J.; Hato, Stanleyson V.; van der Valk, Pieter G.M.; Schröder, Jens Michael; Joosten, Irma; Zeeuwen, Patrick L.J.M.; Schalkwijk, Joost

    2013-01-01

    Topical application of coal tar is one of the oldest therapies for atopic dermatitis (AD), a T helper 2 (Th2) lymphocyte–mediated skin disease associated with loss-of-function mutations in the skin barrier gene, filaggrin (FLG). Despite its longstanding clinical use and efficacy, the molecular mechanism of coal tar therapy is unknown. Using organotypic skin models with primary keratinocytes from AD patients and controls, we found that coal tar activated the aryl hydrocarbon receptor (AHR), resulting in induction of epidermal differentiation. AHR knockdown by siRNA completely abrogated this effect. Coal tar restored filaggrin expression in FLG-haploinsufficient keratinocytes to wild-type levels, and counteracted Th2 cytokine–mediated downregulation of skin barrier proteins. In AD patients, coal tar completely restored expression of major skin barrier proteins, including filaggrin. Using organotypic skin models stimulated with Th2 cytokines IL-4 and IL-13, we found coal tar to diminish spongiosis, apoptosis, and CCL26 expression, all AD hallmarks. Coal tar interfered with Th2 cytokine signaling via dephosphorylation of STAT6, most likely due to AHR-regulated activation of the NRF2 antioxidative stress pathway. The therapeutic effect of AHR activation herein described opens a new avenue to reconsider AHR as a pharmacological target and could lead to the development of mechanism-based drugs for AD. PMID:23348739

  2. Coal tar induces AHR-dependent skin barrier repair in atopic dermatitis.

    PubMed

    van den Bogaard, Ellen H; Bergboer, Judith G M; Vonk-Bergers, Mieke; van Vlijmen-Willems, Ivonne M J J; Hato, Stanleyson V; van der Valk, Pieter G M; Schröder, Jens Michael; Joosten, Irma; Zeeuwen, Patrick L J M; Schalkwijk, Joost

    2013-02-01

    Topical application of coal tar is one of the oldest therapies for atopic dermatitis (AD), a T helper 2 (Th2) lymphocyte-mediated skin disease associated with loss-of-function mutations in the skin barrier gene, filaggrin (FLG). Despite its longstanding clinical use and efficacy, the molecular mechanism of coal tar therapy is unknown. Using organotypic skin models with primary keratinocytes from AD patients and controls, we found that coal tar activated the aryl hydrocarbon receptor (AHR), resulting in induction of epidermal differentiation. AHR knockdown by siRNA completely abrogated this effect. Coal tar restored filaggrin expression in FLG-haploinsufficient keratinocytes to wild-type levels, and counteracted Th2 cytokine-mediated downregulation of skin barrier proteins. In AD patients, coal tar completely restored expression of major skin barrier proteins, including filaggrin. Using organotypic skin models stimulated with Th2 cytokines IL-4 and IL-13, we found coal tar to diminish spongiosis, apoptosis, and CCL26 expression, all AD hallmarks. Coal tar interfered with Th2 cytokine signaling via dephosphorylation of STAT6, most likely due to AHR-regulated activation of the NRF2 antioxidative stress pathway. The therapeutic effect of AHR activation herein described opens a new avenue to reconsider AHR as a pharmacological target and could lead to the development of mechanism-based drugs for AD.

  3. Sampling of tar from sewage sludge gasification using solid phase adsorption.

    PubMed

    Ortiz González, Isabel; Pérez Pastor, Rosa Ma; Sánchez Hervás, José Ma

    2012-06-01

    Sewage sludge is a residue from wastewater treatment plants which is considered to be harmful to the environment and all living organisms. Gasification technology is a potential source of renewable energy that converts the sewage sludge into gases that can be used to generate energy or as raw material in chemical synthesis processes. But tar produced during gasification is one of the problems for the implementation of the gasification technology. Tar can condense on pipes and filters and may cause blockage and corrosion in the engines and turbines. Consequently, to minimize tar content in syngas, the ability to quantify tar levels in process streams is essential. The aim of this work was to develop an accurate tar sampling and analysis methodology using solid phase adsorption (SPA) in order to apply it to tar sampling from sewage sludge gasification gases. Four types of commercial SPA cartridges have been tested to determine the most suitable one for the sampling of individual tar compounds in such streams. Afterwards, the capacity, breakthrough volume and sample stability of the Supelclean™ ENVI-Carb/NH(2), which is identified as the most suitable, have been determined. Basically, no significant influences from water, H(2)S or NH(3) were detected. The cartridge was used in sampling real samples, and comparable results were obtained with the present and traditional methods.

  4. Probing interaction of a fluorescent ligand with HIV TAR RNA

    NASA Astrophysics Data System (ADS)

    Qi, Liang; Zhang, Jing; He, Tian; Huo, Yuan; Zhang, Zhi-Qi

    2017-02-01

    Trans-activator of Transcription (Tat) antagonists could block the interaction between Tat protein and its target, trans-activation responsive region (TAR) RNA, to inhibit Tat function and prevent human immunodeficiency virus type 1 (HIV-1) replication. For the first time, a small fluorescence ligand, ICR 191, was found to interact with TAR RNA at the Tat binding site and compete with Tat. It was also observed that the fluorescence of ICR 191 could be quenched when binding to TAR RNA and recovered when discharged via competition with Tat peptide or a well-known Tat inhibitor, neomycin B. The binding parameters of ICR 191 to TAR RNA were determined through theoretical calculations. Mass spectrometry, circular dichroism and molecular docking were used to further confirm the interaction of ICR 191 with TAR RNA. Inspired by these discoveries, a primary fluorescence model for the discovery of Tat antagonists was built using ICR 191 as a fluorescence indicator and the feasibility of this model was evaluated. This ligand-RNA interaction could provide a new strategy for research aimed at discovering Tat antagonists.

  5. Thermocatalytic treatment of biomass tar model compounds via radio frequency.

    PubMed

    Anis, Samsudin; Zainal, Z A; Bakar, M Z A

    2013-05-01

    A new effective RF tar thermocatalytic treatment process with low energy intensive has been proposed to remove tar from biomass gasification. Toluene and naphthalene as biomass tar model compounds were removed via both thermal and catalytic treatment over a wide temperature range from 850 °C to 1200 °C and 450 °C to 900 °C, respectively at residence time of 0-0.7 s. Thermal characteristics of the new technique are also described in this paper. This study clearly clarified that toluene was much easier to be removed than naphthalene. Soot was found as the final product of thermal treatment of the tar model and completely removed during catalytic treatment. Radical reactions generated by RF non-thermal effect improve the tar removal. The study showed that Y-zeolite has better catalytic activity compared to dolomite on toluene and naphthalene removal due to its acidic nature and large surface area, even at lower reaction temperature of about 550 °C. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Assessment of tar pollution on the United Arab emirates beaches

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

    Abu-Hilal, A.H.; Khordagui, H.K.

    1993-01-01

    In light of the inadequate information concerning stranded tar on the southwest beaches of the Arabian Gulf and the Gulf of Oman, particularly following the massive oil releases during the Gulf War, the present investigation was designed to provide reference-integrated information on the nature, location, and levels of stranded tar balls on the beaches of the United Arab Emirates (UAE). The recorded levels appeared to be higher than expected or previously reported. The tar distribution pattern, in addition to the degree of weathering, indicates that the massive oil release during the Gulf War did not reach the UAE shorelines. Themore » highest reported levels of stranded tar ever recorded in the Arabian Gulf at Jabal Dhannah apparently originated from oil spills and tankers' ballast water at the main oil terminal at the Al-Ruwaiss oil refinery some 10 km to the east. The surprising, relatively high levels of stranded tar on the beaches of the Gulf of Oman were solely attributed to the heavy navigation traffic close to the shorelines. 19 refs., 2 figs., 3 tabs.« less

  7. Evaluation of a new model of aeolian transport in the presence of vegetation

    USGS Publications Warehouse

    Li, Junran; Okin, Gregory S.; Herrick, Jeffrey E.; Belnap, Jayne; Miller, Mark E.; Vest, Kimberly; Draut, Amy E.

    2013-01-01

    Aeolian transport is an important characteristic of many arid and semiarid regions worldwide that affects dust emission and ecosystem processes. The purpose of this paper is to evaluate a recent model of aeolian transport in the presence of vegetation. This approach differs from previous models by accounting for how vegetation affects the distribution of shear velocity on the surface rather than merely calculating the average effect of vegetation on surface shear velocity or simply using empirical relationships. Vegetation, soil, and meteorological data at 65 field sites with measurements of horizontal aeolian flux were collected from the Western United States. Measured fluxes were tested against modeled values to evaluate model performance, to obtain a set of optimum model parameters, and to estimate the uncertainty in these parameters. The same field data were used to model horizontal aeolian flux using three other schemes. Our results show that the model can predict horizontal aeolian flux with an approximate relative error of 2.1 and that further empirical corrections can reduce the approximate relative error to 1.0. The level of error is within what would be expected given uncertainties in threshold shear velocity and wind speed at our sites. The model outperforms the alternative schemes both in terms of approximate relative error and the number of sites at which threshold shear velocity was exceeded. These results lend support to an understanding of the physics of aeolian transport in which (1) vegetation's impact on transport is dependent upon the distribution of vegetation rather than merely its average lateral cover and (2) vegetation impacts surface shear stress locally by depressing it in the immediate lee of plants rather than by changing the bulk surface's threshold shear velocity. Our results also suggest that threshold shear velocity is exceeded more than might be estimated by single measurements of threshold shear stress and roughness length

  8. Cenozoic record of aeolian sediment accumulation and aridification from Lanzhou, China, driven by Tibetan Plateau uplift and global climate

    NASA Astrophysics Data System (ADS)

    Zhang, Yuebao; Sun, Donghuai; Li, Zaijun; Wang, Fei; Wang, Xin; Li, Baofeng; Guo, Feng; Wu, Sheng

    2014-09-01

    Previous work has shown that aeolian Red Clay first appears at around 8 Ma in the main Chinese Loess Plateau and at 25-22 Ma in the western Loess Plateau; however, records of aeolian deposition in the North Pacific suggest that aeolian accumulation occurred throughout the Cenozoic, and that changes in aeolian flux occurred in distinct stages. Tracing the Cenozoic aeolian history of the interior of the Asian continent may help us to understand the history of Asian aridification and its driving forces. In the Lanzhou area on the western margin of the Loess Plateau and the northeastern edge of the Tibetan Plateau, the Cenozoic stratigraphic sequence consists of fluvial-lacustrine sediments in the lower part, aeolian Red Clay with intercalated fluvial layers in the middle part, and predominantly aeolian loess in the upper part. We use high resolution paleomagnetic measurements of this sequence to construct a time scale, and measurements of sediment rock magnetic properties, grain-size, and color reflectance and sedimentary facies analysis to reconstruct the paleoenvironment. The results show that prior to 33 Ma the area was dominantly a fluvial-lacustrine environment, and that subsequently an aridification trend commenced, as indicated by the appearance of aeolian sediment. This change coincided with, and is thus explained as the environmental response to global cooling. A significant increase in aeolian sediments occurred at ~ 26 Ma, suggesting that a large scale arid environment had formed in the Asian interior since the late Oligocene. Stepwise increases of aeolian sediment, and decreases in sediments of hydraulic origin, occurred at ~ 22, ~ 14, ~ 8 and 2.6 Ma and represent important stages in the aridification process. This long-term trend was interrupted by intervals dominated by fluvial sedimentation at 23.6-22 Ma and 17.1-14.1 Ma and which were probably associated with warming of the global climate and the tectonic uplift of the northeastern Tibetan Plateau

  9. High-frequency measurements of aeolian saltation flux: Field-based methodology and applications

    NASA Astrophysics Data System (ADS)

    Martin, Raleigh L.; Kok, Jasper F.; Hugenholtz, Chris H.; Barchyn, Thomas E.; Chamecki, Marcelo; Ellis, Jean T.

    2018-02-01

    Aeolian transport of sand and dust is driven by turbulent winds that fluctuate over a broad range of temporal and spatial scales. However, commonly used aeolian transport models do not explicitly account for such fluctuations, likely contributing to substantial discrepancies between models and measurements. Underlying this problem is the absence of accurate sand flux measurements at the short time scales at which wind speed fluctuates. Here, we draw on extensive field measurements of aeolian saltation to develop a methodology for generating high-frequency (up to 25 Hz) time series of total (vertically-integrated) saltation flux, namely by calibrating high-frequency (HF) particle counts to low-frequency (LF) flux measurements. The methodology follows four steps: (1) fit exponential curves to vertical profiles of saltation flux from LF saltation traps, (2) determine empirical calibration factors through comparison of LF exponential fits to HF number counts over concurrent time intervals, (3) apply these calibration factors to subsamples of the saltation count time series to obtain HF height-specific saltation fluxes, and (4) aggregate the calibrated HF height-specific saltation fluxes into estimates of total saltation fluxes. When coupled to high-frequency measurements of wind velocity, this methodology offers new opportunities for understanding how aeolian saltation dynamics respond to variability in driving winds over time scales from tens of milliseconds to days.

  10. Aeolian sands and buried soils in the Mecklenburg Lake District, NE Germany: Holocene land-use history and pedo-geomorphic response

    NASA Astrophysics Data System (ADS)

    Küster, Mathias; Fülling, Alexander; Kaiser, Knut; Ulrich, Jens

    2014-04-01

    The present study is a pedo-geomorphic approach to reconstructing Holocene aeolian sand dynamics in the Mecklenburg Lake District (NE Germany). Stratigraphical, sedimentological and soil research supplemented by morphogenetic interpretations of the genesis of dunes and aeolian sands are discussed. A complex Late Holocene aeolian stratigraphy within a drift sand area was developed at the shore of Lake Müritz. The results were confirmed using palynological records, archaeological data and regional history. Accelerated aeolian activity was triggered by the intensification of settlement and land-use activities during the 13th and in the 15th to 16th century AD. After a period of stability beginning with population decline during the ‘Thirty Years War' and continuing through the 18th century, a final aeolian phase due to the establishment of glassworks was identified during the 19th century AD. We assume a direct link between Holocene aeolian dynamics and human activities. Prehistoric Holocene drift sands on terrestrial sites have not been documented in the Mecklenburg Lake District so far. This might be explained either by erosion and incorporation of older aeolian sediments during younger aeolian phases and/or a lower regional land-use intensity in older periods of the Holocene. The investigated drift sands are stratigraphically and sedimentologically characterised by a high degree of heterogeneity, reflecting the spatial and temporal variability of Holocene human impact.

  11. Thermodynamic analysis of tar reforming through auto-thermal reforming process

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

    Nurhadi, N., E-mail: nurhadi@tekmira.esdm.go.id; Diniyati, Dahlia; Efendi, M. Ade Andriansyah

    2015-12-29

    Fixed bed gasification is a simple and suitable technology for small scale power generation. One of the disadvantages of this technology is producing tar. So far, tar is not utilized yet and being waste that should be treated into a more useful product. This paper presents a thermodynamic analysis of tar conversion into gas producer through non-catalytic auto-thermal reforming technology. Tar was converted into components, C, H, O, N and S, and then reacted with oxidant such as mixture of air or pure oxygen. Thus, this reaction occurred auto-thermally and reached chemical equilibrium. The sensitivity analysis resulted that the mostmore » promising process performance occurred at flow rate of air was reached 43% of stoichiometry while temperature of process is 1100°C, the addition of pure oxygen is 40% and preheating of oxidant flow is 250°C. The yield of the most promising process performance between 11.15-11.17 kmol/h and cold gas efficiency was between 73.8-73.9%.The results of this study indicated that thermodynamically the conversion of tar into producer gas through non-catalytic auto-thermal reformingis more promising.« less

  12. Groundwater contamination by organic bases derived from coal-tar wastes

    USGS Publications Warehouse

    Pereira, W.E.; Rostad, C.E.; Garbarino, J.R.; Hult, M.F.

    1983-01-01

    A fluid sample from a shallow aquifer contaminated by coal-tar wastes was analyzed for organic bases. The sample consisted of a mixture of aqueous and oily-tar phases. The phases were separated by centrifugation and filtration. Organic bases were isolated from each phase by pH adjustment and solvent extraction. Organic bases in the oily-tar phase were further purified by neutral-alumina, micro-column adsorption chromatography. Separation and identification of the organic bases in each phase were achieved by using capillary gas chromatography-mass spectrometry-computer (GC-MS-COM) and probe distillation-high resolution mass spectrometry (PD-HRMS) techniques. Organic bases present in the aqueous phase included primary aromatic amines (such as aniline, alkylated anilines, and naphthylamines) as well as azaarenes (such as alkylated pyridines, quinolines, acridine, and benzoquinolines). The oily-tar phase contained acridine, benzacridines, dibenzacridines, and numerous other azaarenes, the elemental compositions of which were determined by PD-HRMS. Azaarenes in the oily-tar phase, varying in size from 6 to 12 rings, are reported for the first time. The origin and environmental significance of these compounds are discussed. ?? 1983.

  13. Aeolian processes at the Mars Exploration Rover Meridiani Planum landing site.

    PubMed

    Sullivan, R; Banfield, D; Bell, J F; Calvin, W; Fike, D; Golombek, M; Greeley, R; Grotzinger, J; Herkenhoff, K; Jerolmack, D; Malin, M; Ming, D; Soderblom, L A; Squyres, S W; Thompson, S; Watters, W A; Weitz, C M; Yen, A

    2005-07-07

    The martian surface is a natural laboratory for testing our understanding of the physics of aeolian (wind-related) processes in an environment different from that of Earth. Martian surface markings and atmospheric opacity are time-variable, indicating that fine particles at the surface are mobilized regularly by wind. Regolith (unconsolidated surface material) at the Mars Exploration Rover Opportunity's landing site has been affected greatly by wind, which has created and reoriented bedforms, sorted grains, and eroded bedrock. Aeolian features here preserve a unique record of changing wind direction and wind strength. Here we present an in situ examination of a martian bright wind streak, which provides evidence consistent with a previously proposed formational model for such features. We also show that a widely used criterion for distinguishing between aeolian saltation- and suspension-dominated grain behaviour is different on Mars, and that estimated wind friction speeds between 2 and 3 m s(-1), most recently from the northwest, are associated with recent global dust storms, providing ground truth for climate model predictions.

  14. Aeolian processes at the Mars Exploration Rover Meridiani Planum landing site

    USGS Publications Warehouse

    Sullivan, R.; Banfield, D.; Bell, J.F.; Calvin, W.; Fike, D.; Golombek, M.; Greeley, R.; Grotzinger, J.; Herkenhoff, K.; Jerolmack, D.; Malin, M.; Ming, D.; Soderblom, L.A.; Squyres, S. W.; Thompson, S.; Watters, W.A.; Weitz, C.M.; Yen, A.

    2005-01-01

    The martian surface is a natural laboratory for testing our understanding of the physics of aeolian (wind-related) processes in an environment different from that of Earth. Martian surface markings and atmospheric opacity are time-variable, indicating that fine particles at the surface are mobilized regularly by wind. Regolith (unconsolidated surface material) at the Mars Exploration Rover Opportunity's landing site has been affected greatly by wind, which has created and reoriented bedforms, sorted grains, and eroded bedrock. Aeolian features here preserve a unique record of changing wind direction and wind strength. Here we present an in situ examination of a martian bright wind streak, which provides evidence consistent with a previously proposed formational model for such features. We also show that a widely used criterion for distinguishing between aeolian saltation- and suspension-dominated grain behaviour is different on Mars, and that estimated wind friction speeds between 2 and 3 m s-1, most recently from the northwest, are associated with recent global dust storms, providing ground truth for climate model predictions.

  15. Monitoring of aeolian desertification on the Qinghai-Tibet Plateau from the 1970s to 2015 using Landsat images.

    PubMed

    Zhang, Chun-Lai; Li, Qing; Shen, Ya-Ping; Zhou, Na; Wang, Xue-Song; Li, Jiao; Jia, Wen-Ru

    2018-04-01

    Aeolian desertification, one of the most serious environmental issues, has hampered socioeconomic development on the Qinghai-Tibet Plateau (QTP). However, research on aeolian desertification in this region has been limited. To develop a set of science-based preventive measures to mitigate desertification in this region, it is first necessary to clarify the status, evolution, and driving factors of aeolian desertification. In this study, based on extensive field investigations and a current classification system for aeolian desertification, we established a new system for interpreting aeolian desertified land (ADL) on the plateau using Landsat images from 1977, 1990, 2000, 2010, and 2015 and obtained the distribution of ADL through visual interpretation of the images. The results showed that ADL covered 392,914km 2 (15.1% of the study area) in 2015, including gravel ADL, sandy ADL, and aeolian monadnocks. Controlled by climate, landforms, the type of Quaternary deposit, and human activities, ADL is scattered throughout the plateau but is concentrated mostly in the western and northern parts. Aeolian desertification on the plateau expanded from 1977 to 2000 and then began to reverse. The evolution during the study period is the result of the combined effects of natural and human factors. Irrational human activities were the dominant factor responsible for the expansion of ADL prior to 2000, whereas the subsequent reversal was mainly caused by climate change combined with large ecological restoration projects. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Deciphering structure-activity relationships in a series of Tat/TAR inhibitors.

    PubMed

    Pascale, Lise; González, Alejandro López; Di Giorgio, Audrey; Gaysinski, Marc; Teixido Closa, Jordi; Tejedor, Roger Estrada; Azoulay, Stéphane; Patino, Nadia

    2016-11-01

    A series of pentameric "Polyamide Amino Acids" (PAAs) compounds derived from the same trimeric precursor have been synthesized and investigated as HIV TAR RNA ligands, in the absence and in the presence of a Tat fragment. All PAAs bind TAR with similar sub-micromolar affinities but their ability to compete efficiently with the Tat fragment strongly differs, IC50 ranging from 35 nM to >2 μM. While NMR and CD studies reveal that all PAA interact with TAR at the same site and induce globally the same RNA conformational change upon binding, a comparative thermodynamic study of PAA/TAR equilibria highlights distinct TAR binding modes for Tat competitor and non-competitor PAAs. This led us to suggest two distinct interaction modes that have been further validated by molecular modeling studies. While the binding of Tat competitor PAAs induces a contraction at the TAR bulge region, the binding of non-competitor ones widens it. This could account for the distinct PAA ability to compete with Tat fragment. Our work illustrates how comparative thermodynamic studies of a series of RNA ligands of same chemical family are of value for understanding their binding modes and for rationalizing structure-activity relationships.

  17. Aeolian cliff-top deposits and buried soils in the White River Badlands, South Dakota, USA

    USGS Publications Warehouse

    Rawling, J. E.; Fredlund, G.G.; Mahan, S.

    2003-01-01

    Aeolian deposits in the North American Great Plains are important sources of Holocene palaeo-environmental records. Although there are extensive studies on loess and dune records in the region, little is known about records in aeolian cliff-top deposits. These are common on table (mesa) edges in the White River Badlands. These sediments typically have loam and sandy-loam textures with dominantly very fine sand, 0.5-1% organic carbon and 0.5-5% CaCO3. Some of these aeolian deposits are atypically coarse and contain granules and fine pebbles. Buried soils within these deposits are weakly developed with A-C and A-AC-C profiles. Beneath these are buried soils with varying degrees of pedogenic development formed in fluvial, aeolian or colluvial deposits. Thickness and number of buried soils vary. However, late-Holocene soils from several localities have ages of approximately 1300, 2500 and 3700 14C yrs BP. The 1300 14C yr BP soil is cumulic, with a thicker and lighter A horizon. Soils beneath the cliff-top deposits are early-Holocene (typically 7900 but as old as 10000 14C yrs BP) at higher elevation (???950 m) tables, and late-Holocene (2900 14C yrs BP) at lower (???830 m) tables. These age estimates are based on total organic matter 14C ages from the top 5 cm of buried soils, and agreement is good between an infrared stimulated luminescence age and bracketing 14C ages. Our studies show that cliff-top aeolian deposits have a history similar to that of other aeolian deposits on the Great Plains, and they are another source of palaeoenvironmental data.

  18. Ridge suction drives plume-ridge interactions

    NASA Astrophysics Data System (ADS)

    Niu, Y.; Hékinian, R.

    2003-04-01

    Deep-sourced mantle plumes, if existing, are genetically independent of plate tectonics. When the ascending plumes approach lithospheric plates, interactions between the two occur. Such interactions are most prominent near ocean ridges where the lithosphere is thin and the effect of plumes is best revealed. While ocean ridges are mostly passive features in terms of plate tectonics, they play an active role in the context of plume-ridge interactions. This active role is a ridge suction force that drives asthenospheric mantle flow towards ridges because of material needs to form the ocean crust at ridges and lithospheric mantle in the vicinity of ridges. This ridge suction force increases with increasing plate separation rate because of increased material demand per unit time. As the seismic low-velocity zone atop the asthenosphere has the lowest viscosity that increases rapidly with depth, the ridge-ward asthenospheric flow is largely horizontal beneath the lithosphere. Recognizing that plume materials have two components with easily-melted dikes/veins enriched in volatiles and incompatible elements dispersed in the more refractory and depleted peridotitic matrix, geochemistry of some seafloor volcanics well illustrates that plume-ridge interactions are consequences of ridge-suction-driven flow of plume materials, which melt by decompression because of lithospheric thinning towards ridges. There are excellent examples: 1. The decreasing La/Sm and increasing MgO and CaO/Al_2O_3 in Easter Seamount lavas from Salas-y-Gomez Islands to the Easter Microplate East rift zone result from progressive decompression melting of ridge-ward flowing plume materials. 2. The similar geochemical observations in lavas along the Foundation hotline towards the Pacific-Antarctic Ridge result from the same process. 3. The increasing ridge suction force with increasing spreading rate explains why the Iceland plume has asymmetric effects on its neighboring ridges: both topographic and

  19. The developmental trend and influencing factors of aeolian desertification in the Zoige Basin, eastern Qinghai-Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Hu, Guangyin; Dong, Zhibao; Lu, Junfeng; Yan, Changzhen

    2015-12-01

    The Zoige Basin is located in the northeastern region of the Qinghai-Tibet Plateau and covers an area of 19,400 km2. At a mean altitude of 3500 m, the basin is highly sensitive to global environmental change and human disturbance due to its high elevation and fragile cold environment. The process of aeolian desertification in the basin can be clearly recognized in Landsat images that show the development of sand sheets and dunes over time. To monitor the spatial and temporal changes of aeolian desertification in the Zoige Basin, we analyzed Landsat images recorded in 1975, 1990, 2000, 2005, and 2010. Results showed that aeolian desertification increased rapidly from 1975 to 1990, was stable from 1990 to 2000, decreased slightly from 2000 to 2005, and decreased sharply from 2005 to 2010. Increasing temperature, overgrazing, rodent damage, and drainage of wetlands were considered the key driving factors of the expansion of aeolian desertification. A number of political measures were initiated in the 1990s to slow desertification, but the countermeasures of grazing prohibition, enclosures, and paving straw checkerboard barriers were not implemented until around 2005. These measures resulted in a dramatic recovery of aeolian desertified land between 2005 and 2010. Based on the cause analysis, anthropogenic factors were identified as the dominant driving force for both development and recovery of aeolian desertified land.

  20. Sedimentology and preservation of aeolian sediments on steep terrains: Incipient sand ramps on the Atacama coast (northern Chile)

    NASA Astrophysics Data System (ADS)

    Ventra, Dario; Rodríguez-López, Juan Pedro; de Boer, Poppe L.

    2017-05-01

    The origin of topographically controlled aeolian landforms in high-relief settings is difficult to synthesize under general models, given the dependence of such accumulations on local morphology. Quaternary sand ramps have been linked to palaeoclimate, regional geomorphology and wind patterns; however, controls on the early development and preservation of such landforms are poorly known. This study describes the morphology and sedimentology of complex sedimentary aprons along steep coastal slopes in the Atacama Desert (Chile). Direct slope accessibility and continuous stratigraphic exposures enable comparisons between active processes and stratigraphic signatures. Stratigraphic facies distribution and its links with patterns of aeolian deposition show that the preservation of wind-laid sediments depends on the morphology and processes of specific slope sectors. The spatial organization of runoff depends on bedrock configuration and directly controls the permanence or erosion of aeolian sediment. The occurrence of either water or mass flows depends on the role of aeolian fines in the rheology of flash floods. In turn, the establishment of a rugged surface topography controlled by patterns of mass-flow deposition creates local accommodation for aeolian fines, sustaining the initial aggradation of a colluvial-aeolian system. By contrast, slopes subject to runoff develop a thin, extensive aeolian mantle whose featureless surface is subject mostly to sediment bypass down- and across-slope; the corresponding stratigraphic record comprises almost exclusively thin debris-flow and sheetflood deposits. Slope morphology and processes are fundamental in promoting or inhibiting aeolian aggradation in mountain settings. Long-term sand-ramp construction depends on climate and regional topography, but the initial development is probably controlled by local geomorphic factors. The observed interactions between wind and topography in the study area may also represent a process

  1. Effect of water addition in a microwave assisted thermal cracking of biomass tar gasification

    NASA Astrophysics Data System (ADS)

    Warsita, A.; Surya, I.

    2018-02-01

    Producer gas from biomass gasification is plagued by the presence of tar which causes pipe blockages. Thermal and catalytic treatments in a microwave reactor have been shown to be effective methods for removing tar from producer gas. A question arises as to the possibility of enhancing the removal mechanism by adding water into the reactor. Thermal treatment with a various amount of water was added at temperatures in the range of 800-1200°C. The tar removal efficiency obtained 96.32% at the optimum temperature of 1200°C at the water to tar ratio (W/T) of 0.3. This study shows that the removal of tar by microwave irradiation with water addition is a significant and effective method in tar cracking.

  2. Facies architecture and stratigraphic evolution of aeolian dune and interdune deposits, Permian Caldeirão Member (Santa Brígida Formation), Brazil

    NASA Astrophysics Data System (ADS)

    Jones, Fábio Herbert; Scherer, Claiton Marlon dos Santos; Kuchle, Juliano

    2016-05-01

    The Permian Caldeirão Member (Santa Brígida Formation), located in the Tucano Central Basin, northeast region of Brazil, is characterized by a sandstone succession of aeolian origin that comprises the preserved deposits of dunes and interdunes. Grainflow and translatent wind-ripple strata, and frequent presence of reactivation surface, compose the cross-bedding of crescent aeolian dune deposits. The aeolian cross-strata show a mean dip toward the ENE. In places, interlayered with dune cross-beds, occur interdune units composed of facies indicative of dry, damp and wet condition of the substrate, suggesting spatial and/or temporal variations in the moisture content of the interdune accumulation surface. The presence of NNW current ripple cross-lamination in wet interdune areas indicates streamflows confined to interdune corridors and oriented perpendicular to aeolian transport direction. Lenses of damp and wet interdune strata exhibit mainly interdigitated and transitional relationships with the toe-sets of overlying aeolian dune units in sections parallel to aeolian transport, indicating that dune migration was contemporaneous with accumulation in adjacent interdunes. Lateral variations in the preserved thickness of the interdune units and the associated rare occurrence of abrupt and erosive contacts between interdune and overlying dune sets, suggest temporal variations in the angle of dune and interdune climb that may be related to high-frequency changes in water table position. Four stratigraphic intervals in the Caldeirão Member can be identified, two intervals showing cross-bedding of aeolian dunes without wet interdune areas and two intervals exhibiting aeolian dunes separated by wet interdune areas, marking the transition between dry aeolian systems (Intervals I and III) and wet aeolian systems (Intervals II and IV). The temporal alternations between dry and wet aeolian systems reflect changes in the availability of dry sand and/or the rate in the water

  3. The TAR effect: when the ones who dislike become the ones who are disliked.

    PubMed

    Gawronski, Bertram; Walther, Eva

    2008-09-01

    Four studies tested whether a source's evaluations of other individuals can recursively transfer to the source, such that people who like others acquire a positive valence, whereas people who dislike others acquire a negative valence (Transfer of Attitudes Recursively; TAR). Experiment 1 provides first evidence for TAR effects, showing recursive transfers of evaluations regardless of whether participants did or did not have prior knowledge about the (dis)liking source. Experiment 2 shows that previously but not subsequently acquired knowledge about targets that were (dis)liked by a source overrode TAR effects in a manner consistent with cognitive balance. Finally, Experiments 3 and 4 demonstrate that TAR effects are mediated by higher order propositional inferences (in contrast to lower order associative processes), in that TAR effects on implicit attitude measures were fully mediated by TAR effects on explicit attitude measures. Commonalities and differences between the TAR effect and previously established phenomena are discussed.

  4. Coal-tar based pavement sealant toxicity to freshwater macroinvertebrates.

    PubMed

    Bryer, Pamela J; Scoggins, Mateo; McClintock, Nancy L

    2010-05-01

    Non-point-source pollution is a major source of ecological impairment in urban stream systems. Recent work suggests that coal-tar pavement sealants, used extensively to protect parking areas, may be contributing a large portion of the polycyclic aromatic hydrocarbon (PAH) loading seen in urban stream sediments. The hypothesis that dried coal-tar pavement sealant flake could alter the macroinvertebrate communities native to streams in Austin, TX was tested using a controlled outdoor laboratory type approach. The treatment groups were: control, low, medium, and high with total PAH concentrations (TPAH = sum of 16 EPA priority pollutant PAHs) of 0.1, 7.5, 18.4, & 300 mg/kg respectively. The low, medium, and high treatments were created via the addition of dried coal-tar pavement sealant to a sterile soil. At the start of the 24-day exposure, sediment from a minimally impacted local reference site containing a community of live sediment-dwelling benthic macroinvertebrates was added to each replicate. An exposure-dependent response was found for several stream health measures and for several individual taxa. There were community differences in abundance (P = 0.0004) and richness (P < 0.0001) between treatments in addition to specific taxa responses, displaying a clear negative relationship with the amount of coal-tar sealant flake. These results support the hypothesis that coal-tar pavement sealants contain bioavailable PAHs that may harm aquatic environments. Copyright 2009 Elsevier Ltd. All rights reserved.

  5. Ground-water contamination by organic bases derived from coal-tar wastes

    USGS Publications Warehouse

    Pereira, Wilfred E.; Rostad, Colleen E.; Garbarino, John R.; Hult, Marc F.

    1983-01-01

    A fluid sample from a shallow aquifer contaminated by coal-tar wastes was analyzed for organic bases. The sample consisted of a mixture of aqueous and oily-tar phases. The phases were separated by centrifugation and filtration. Organic bases were isolated from each phase by pH adjustment and solvent extraction. Organic bases in the oily-tar phase were further purified by neutral-alumina, micro-column adsorption chromatography. Separation and identification of the organic bases in each phase were achieved by using capillary gas chromatography-mass spectrometry-computer (GC-MS-COM) and probe distillation-high resolution mass spectrometry (PD-HRMS) techniques. Organic bases present in the aqueous phase included primary aromatic amines (such as aniline, alkylated anilines, and naphthylamines) as well as azaarenes (such as alkylated pyridines, quinolines, acridine, and benzoquinolines). The oily-tar phase contained acridine, benzacridines, dibenzacridines, and numerous other azaarenes, the elemental compositions of which were determined by PD-HRMS. Azaarenes in the oily-tar phase, varying in size from 6 to 12 rings, are reported for the first time. The origin and environmental significance of these compounds are discussed.

  6. Giant calcite concretions in aeolian dune sandstones; sedimentological and architectural controls on diagenetic heterogeneity, mid-Cretaceous Iberian Desert System, Spain

    NASA Astrophysics Data System (ADS)

    Arribas, Maria Eugenia; Rodríguez-López, Juan Pedro; Meléndez, Nieves; Soria, Ana Rosa; de Boer, Poppe L.

    2012-01-01

    Aeolian dune sandstones of the Iberian erg system (Cretaceous, Spain) host giant calcite concretions that constitute heterogeneities of diagenetic origin within a potential aeolian reservoir. The giant calcite concretions developed in large-scale aeolian dune foresets, at the transition between aeolian dune toeset and damp interdune elements, and in medium-scale superimposed aeolian dune sets. The chemical composition of the giant concretions is very homogeneous. They formed during early burial by low Mg-calcite precipitation from meteoric pore waters. Carbonate components with yellow/orange luminescence form the nuclei of the poikilotopic calcite cement. These cements postdate earlier diagenetic features, characterized by early mechanical compaction, Fe-oxide cements and clay rims around windblown quartz grains resulting from the redistribution of aeolian dust over the grain surfaces. The intergranular volume (IGV) in friable aeolian sandstone ranges from 7.3 to 15.3%, whereas in cemented aeolian sandstone it is 18.6 to 25.3%. The giant-calcite concretions developed during early diagenesis under the influence of meteoric waters associated with the groundwater flow of the desert basin, although local (e.g. activity of fluid flow through extensional faults) and/or other regional controls (e.g. variations of the phreatic level associated with a variable water influx to the erg system and varying sea level) could have favoured the local development of giant-calcite concretions. The spatial distribution pattern of carbonate grains and the main bounding surfaces determined the spatial distribution of the concretions. In particular, the geometry of the giant calcite concretions is closely associated with main bounding aeolian surfaces. Thus, interdune, superimposition and reactivation surfaces exerted a control on the concretion geometries ranging from flat and tabular ones (e.g. bounded by interdunes) to wedge-shaped concretions at the dune foresets (e.g. bounded by

  7. Where on Earth can we find Mars? Characterization of an Aeolian Analogue in Northwestern Argentina

    NASA Astrophysics Data System (ADS)

    Favaro, E. A.; Hugenholtz, C.; Barchyn, T.

    2017-12-01

    The Puna Plateau of northwestern Argentina is as a promising analogue for Martian aeolian processes owing to its altitude, low atmospheric pressure, aridity, and widespread granular and bedrock aeolian features. The study was conducted in and surrounding the area known as the Campo de Piedra Pómez - a prominent expanse of wind-carved ignimbrite in Argentina's Catamarca Province. To interpret the evolution of this unique laboratory, which is limited by its isolated location and dearth of in situ measurements, we investigated contemporary aeolian sediment transport through a combination of modeled meteorological data, satellite imagery, field measurements, and sediment traps. Our objective is to utilize modeled meteorological data, satellite imagery, and field measurements and samples to characterize the aeolian environment here to base analogue studies. Satellite imagery from Terra MODIS, GeoEye, and Ikonos indicate recent large-scale aeolian sediment transport events and migration of gravel in the region. A prominent, region-wide sediment transport event on 14 August 2015 coincided with synoptic-scale pressure patterns indicating a strong Zonda (Foehn) winds. Sediment traps and marbles provide additional evidence of wind-driven transport of sand and gravel. Yet, despite the body of evidence for sediment transport on the Puna Plateau, modeled wind data from the European Center for Midrange Weather Forecasting suggest wind rarely attains the speeds necessary to initiate sediment transport. This disconnect is reminiscent of the Martian Saltation Paradox which suggested winds on Mars were incapable of mobilizing sediment, despite widespread evidence from rover, lander, and satellite observations. This raises questions about: (i) the suitability of modeled wind data for characterizing aeolian processes on both planets, and (ii) the possibility that most geomorphic work is conducted in extreme, but infrequent events in this region (possibly analogous to Mars). We

  8. Dynamics of aeolian desertification and its driving forces in the Horqin Sandy Land, Northern China.

    PubMed

    Duan, Han-chen; Wang, Tao; Xue, Xian; Liu, Shu-lin; Guo, Jian

    2014-10-01

    Aeolian desertification is one of the most serious environmental and socioeconomic problems in arid, semi-arid, and dry subhumid zones. Understanding desertification processes and causes is important to provide reasonable and effective control measures for preventing desertification. With satellite remote sensing images as data source to assess the temporal and spatial dynamics of desertification from 1975 to 2010 in the Horqin Sandy Land, dynamic changes of aeolian desertification were detected using the human-machine interactive interpretation method. The driving factors of local desertification were analyzed based on natural and socioeconomic data. The results show that aeolian desertified land in the study area covered 30,199 km(2) in 2010, accounting for 24.1% of the study area. The total area of aeolian desertified land obviously expanded from 30,884 km(2) in 1975 to 32,071 km(2) in 1990, and gradually decreased to 30,199 km(2) in 2010; aeolian desertified land represented an increasing trend firstly and then decreased. During the past 35 years, the gravity centers of desertified lands that are classified as extremely severe and severe generally migrated to the northeast, whereas those that are moderate and slight migrated to the northwest. The migration distance of severely desertified land was the largest, which indicated the southern desertified lands were improved during the last few decades. In addition, the climatic variation in the past 35 years has been favorable to desertification in the Horqin Sandy Land. Aeolian desertified land rapidly expanded from 1975 to 1990 under the combined effects of climate changes and unreasonable human activities. After the 1990s, the main driving factors responsible for the decrease in desertification were positive human activities, such as the series of antidesertification and ecological restoration projects.

  9. Role of TAR RNA splicing in translational regulation of simian immunodeficiency virus from rhesus macaques.

    PubMed Central

    Viglianti, G A; Rubinstein, E P; Graves, K L

    1992-01-01

    The untranslated leader sequences of rhesus macaque simian immunodeficiency virus mRNAs form a stable secondary structure, TAR. This structure can be modified by RNA splicing. In this study, the role of TAR splicing in virus replication was investigated. The proportion of viral RNAs containing a spliced TAR structure is high early after infection and decreases at later times. Moreover, proviruses containing mutations which prevent TAR splicing are significantly delayed in replication. These mutant viruses require approximately 20 days to achieve half-maximal virus production, in contrast to wild-type viruses, which require approximately 8 days. We attribute this delay to the inefficient translation of unspliced-TAR-containing mRNAs. The molecular basis for this translational effect was examined in in vitro assays. We found that spliced-TAR-containing mRNAs were translated up to 8.5 times more efficiently than were similar mRNAs containing an unspliced TAR leader. Furthermore, these spliced-TAR-containing mRNAs were more efficiently associated with ribosomes. We postulate that the level of TAR splicing provides a balance for the optimal expression of both viral proteins and genomic RNA and therefore ultimately controls the production of infectious virions. Images PMID:1629957

  10. Selected constituents in the smoke of domestic low tar cigarettes

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

    Griest, W. H.; Quincy, R. B.; Guerin, M. R.

    Thirty-two brands of domestic commercial low tar and nicotine cigarettes were analyzed for their production of tar, nicotine, nitrogen oxides (as nitric oxide), hydrogen cyanide, acrolein, carbon monoxide and carbon dioxide under standard analytical smoking conditions. Results are compared with published data for certain brands.

  11. The contribution of low tar cigarettes to environmental tobacco smoke

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

    Chortyk, O.T.; Schlotzhauer, W.S.

    A series of low tar cigarettes (LTC) were smoked and the quantities of condensable mainstream (inhaled) and sidestream (between puffs) smoke compounds were determined and compared to those produced by a high tar, nonfilter cigarette. It was found that the LTC produced large quantities of sidestream smoke condensates, about equal to the high tar cigarette, and contained very high levels of toxic or cocarcinogenic phenols. On an equal weight basis, the LTC emitted more of these hazardous compounds into sidestream and environmental tobacco smoke. Higher smoke yields of a flavor additive and a sugar degradation product indicated addition of suchmore » compounds during the manufacture of LTC. It was concluded that, compared to a high tar cigarette, smoking LTC may be better for the smoker, but not for the nearby nonsmoker. Information should be developed to allow smokers to choose LTC that produce lower levels of hazardous compounds in their environmentally emitted sidestream smoke.« less

  12. Creating fluid injectivity in tar sands formations

    DOEpatents

    Stegemeier, George Leo; Beer, Gary Lee; Zhang, Etuan

    2012-06-05

    Methods for treating a tar sands formation are described herein. Methods for treating a tar sands may include heating a portion of a hydrocarbon layer in the formation from one or more heaters located in the portion. The heat may be controlled to increase the permeability of at least part of the portion to create an injection zone in the portion with an average permeability sufficient to allow injection of a fluid through the injection zone. A drive fluid and/or an oxidizing fluid may be provided into the injection zone. At least some hydrocarbons including mobilized hydrocarbons are produced from the portion.

  13. Creating fluid injectivity in tar sands formations

    DOEpatents

    Stegemeier, George Leo; Beer, Gary Lee; Zhang, Etuan

    2010-06-08

    Methods for treating a tar sands formation are described herein. Methods for treating a tar sands may include heating a portion of a hydrocarbon layer in the formation from one or more heaters located in the portion. The heat may be controlled to increase the permeability of at least part of the portion to create an injection zone in the portion with an average permeability sufficient to allow injection of a fluid through the injection zone. A drive fluid and/or an oxidizing fluid may be provided into the injection zone. At least some hydrocarbons are produced from the portion.

  14. Influence of aeolian activities on the distribution of microbial abundance in glacier ice

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Li, X.-K.; Si, J.; Wu, G.-J.; Tian, L.-D.; Xiang, S.-R.

    2014-10-01

    Microorganisms are continuously blown onto the glacier snow, and thus the glacial depth profiles provide excellent archives of microbial communities and climatic and environmental changes. However, it is uncertain about how aeolian processes that cause climatic changes control the distribution of microorganisms in the glacier ice. In the present study, microbial density, stable isotopic ratios, 18O / 16O in the precipitation, and mineral particle concentrations along the glacial depth profiles were collected from ice cores from the Muztag Ata glacier and the Dunde ice cap. The ice core data showed that microbial abundance was often, but not always associated with high concentrations of particles. Results also revealed clear seasonal patterning with high microbial abundance occurring in both the cooling autumn and warming spring-summer seasons. Microbial comparisons among the neighbouring glaciers display a heterogeneous spatial pattern, with the highest microbial cell density in the glaciers lying adjacent to the central Asian deserts and lowest microbial density in the southwestern margin of the Tibetan Plateau. In conclusion, microbial data of the glaciers indicates the aeolian deposits of microorganisms in the glacier ice and that the spatial patterns of microorgansisms are related to differences in sources of microbial flux and intensity of aeolian activities in the current regions. The results strongly support our hypothesis of aeolian activities being the main agents controlling microbial load in the glacier ice.

  15. A conceptual framework for dryland aeolian sediment transport along the grassland–forest continuum: Effects of woody plant canopy cover and disturbance

    USGS Publications Warehouse

    Breshears, D.D.; Whicker, J.J.; Zou, C.B.; Field, J.P.; Allen, Craig D.

    2009-01-01

    Aeolian processes are of particular importance in dryland ecosystems where ground cover is inherently sparse because of limited precipitation. Dryland ecosystems include grassland, shrubland, savanna, woodland, and forest, and can be viewed collectively as a continuum of woody plant cover spanning from grasslands with no woody plant cover up to forests with nearly complete woody plant cover. Along this continuum, the spacing and shape of woody plants determine the spatial density of roughness elements, which directly affects aeolian sediment transport. Despite the extensiveness of dryland ecosystems, studies of aeolian sediment transport have generally focused on agricultural fields, deserts, or highly disturbed sites where rates of transport are likely to be greatest. Until recently, few measurements have been made of aeolian sediment transport over multiple wind events and across a variety of types of dryland ecosystems. To evaluate potential trends in aeolian sediment transport as a function of woody plant cover, estimates of aeolian sediment transport from recently published studies, in concert with rates from four additional locations (two grassland and two woodland sites), are reported here. The synthesis of these reports leads to the development of a new conceptual framework for aeolian sediment transport in dryland ecosystems along the grassland–forest continuum.The findings suggest that: (1) for relatively undisturbed ecosystems, shrublands have inherently greater aeolian sediment transport because of wake interference flow associated with intermediate levels of density and spacing of woody plants; and (2) for disturbed ecosystems, the upper bound for aeolian sediment transport decreases as a function of increasing amounts of woody plant cover because of the effects of the height and density of the canopy on airflow patterns and ground cover associated with woody plant cover. Consequently, aeolian sediment transport following disturbance spans the

  16. A conceptual framework for dryland aeolian sediment transport along the grassland-forest continuum: Effects of woody plant canopy cover and disturbance

    NASA Astrophysics Data System (ADS)

    Breshears, David D.; Whicker, Jeffrey J.; Zou, Chris B.; Field, Jason P.; Allen, Craig D.

    2009-04-01

    Aeolian processes are of particular importance in dryland ecosystems where ground cover is inherently sparse because of limited precipitation. Dryland ecosystems include grassland, shrubland, savanna, woodland, and forest, and can be viewed collectively as a continuum of woody plant cover spanning from grasslands with no woody plant cover up to forests with nearly complete woody plant cover. Along this continuum, the spacing and shape of woody plants determine the spatial density of roughness elements, which directly affects aeolian sediment transport. Despite the extensiveness of dryland ecosystems, studies of aeolian sediment transport have generally focused on agricultural fields, deserts, or highly disturbed sites where rates of transport are likely to be greatest. Until recently, few measurements have been made of aeolian sediment transport over multiple wind events and across a variety of types of dryland ecosystems. To evaluate potential trends in aeolian sediment transport as a function of woody plant cover, estimates of aeolian sediment transport from recently published studies, in concert with rates from four additional locations (two grassland and two woodland sites), are reported here. The synthesis of these reports leads to the development of a new conceptual framework for aeolian sediment transport in dryland ecosystems along the grassland-forest continuum. The findings suggest that: (1) for relatively undisturbed ecosystems, shrublands have inherently greater aeolian sediment transport because of wake interference flow associated with intermediate levels of density and spacing of woody plants; and (2) for disturbed ecosystems, the upper bound for aeolian sediment transport decreases as a function of increasing amounts of woody plant cover because of the effects of the height and density of the canopy on airflow patterns and ground cover associated with woody plant cover. Consequently, aeolian sediment transport following disturbance spans the largest

  17. 21 CFR 740.18 - Coal tar hair dyes posing a risk of cancer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 7 2012-04-01 2012-04-01 false Coal tar hair dyes posing a risk of cancer. 740.18... (CONTINUED) COSMETICS COSMETIC PRODUCT WARNING STATEMENTS Warning Statements § 740.18 Coal tar hair dyes... coal tar hair dye containing any ingredient listed in paragraph (b) of this section shall bear, in...

  18. Aeolian Sand Transport with Collisional Suspension

    NASA Technical Reports Server (NTRS)

    Jenkins, James T.; Pasini, Jose Miguel; Valance, Alexandre

    2004-01-01

    Aeolian transport is an important mechanism for the transport of sand on Earth and on Mars. Dust and sand storms are common occurrences on Mars and windblown sand is responsible for many of the observed surface features, such as dune fields. A better understanding of Aeolian transport could also lead to improvements in pneumatic conveying of materials to be mined for life support on the surface of the Moon and Mars. The usual view of aeolian sand transport is that for mild winds, saltation is the dominant mechanism, with particles in the bed being dislodged by the impact of other saltating particles, but without in-flight collisions. As the wind becomes stronger, turbulent suspension keeps the particles in the air, allowing much longer trajectories, with the corresponding increase in transport rate. We show here that an important regime exists between these two extremes: for strong winds, but before turbulent suspension becomes dominant, there is a regime in which in-flight collisions dominate over turbulence as a suspension mechanism, yielding transport rates much higher than those for saltation. The theory presented is based on granular kinetic theory, and includes both turbulent suspension and particle-particle collisions. The wind strengths for which the calculated transport rates are relevant are beyond the published strengths of current wind tunnel experiments, so these theoretical results are an invitation to do experiments in the strong-wind regime. In order to make a connection between the regime of saltation and the regime of collisional suspension, it is necessary to better understand the interaction between the bed and the particles that collide with it. This interaction depends on the agitation of the particles of the bed. In mild winds, collisions with the bed are relatively infrequent and the local disturbance associated with a collision can relax before the next nearby collision. However, as the wind speed increases, collision become more frequent

  19. Surprises from the field: Novel aspects of aeolian saltation observed under natural turbulence

    NASA Astrophysics Data System (ADS)

    Martin, R. L.; Kok, J. F.; Chamecki, M.

    2015-12-01

    The mass flux of aeolian (wind-blown) sediment transport - critical for understanding earth and planetary geomorphology, dust generation, and soil stability - is difficult to predict. Recent work suggests that competing models for saltation (the characteristic hopping of aeolian sediment) fail because they do not adequately account for wind turbulence. To address this issue, we performed field deployments measuring high-frequency co-variations of aeolian saltation and near-surface winds at multiple sites under a range of conditions. Our observations yield several novel findings not currently captured by saltation models: (1) Saltation flux displays no significant lag relative to horizontal wind velocity; (2) Characteristic height of the saltation layer remains constant with changes in shear velocity; and (3) During saltation, the vertical profile of mean horizontal wind velocity is steeper than expected from the Reynolds stress. We examine how the interactions between saltation and turbulence in field settings could explain some of these surprising observations.

  20. Understanding the stability of pyrolysis tars from biomass in a view point of free radicals.

    PubMed

    He, Wenjing; Liu, Qingya; Shi, Lei; Liu, Zhenyu; Ci, Donghui; Lievens, Caroline; Guo, Xiaofen; Liu, Muxin

    2014-03-01

    Fast pyrolysis of biomass has attracted increasing attention worldwide to produce bio-tars that can be upgraded into liquid fuels and chemicals. However, the bio-tars are usually poor in quality and stability and are difficult to be upgraded. To better understand the nature of the bio-tars, this work reveals radical concentration of tars derived from pyrolysis of two kinds of biomass. The tars were obtained by condensing the pyrolysis volatiles in 3s. It shows that the tars contain large amounts of radicals, at a level of 10(16)spins/g, and are able to generate more radicals at temperatures of 573K or higher, reaching a level of 10(19)spins/g at 673K in less than 30min. The radical generation in the tar samples is attributed to the formation of THF insoluble matters (coke), which also contain radicals. The radical concentrations of the aqueous liquids obtained in pyrolysis are also studied. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Catalytic Tar Reduction for Assistance in Thermal Conversion of Space Waste for Energy Production

    NASA Technical Reports Server (NTRS)

    Caraccio, Anne Joan; Devor, Robert William; Hintze, Paul E.; Muscatello, Anthony C.; Nur, Mononita

    2014-01-01

    The Trash to Gas (TtG) project investigates technologies for converting waste generated during spaceflight into various resources. One of these technologies was gasification, which employed a downdraft reactor designed and manufactured at NASA's Kennedy Space Center (KSC) for the conversion of simulated space trash to carbon dioxide. The carbon dioxide would then be converted to methane for propulsion and water for life support systems. A minor byproduct of gasification includes large hydrocarbons, also known as tars. Tars are unwanted byproducts that add contamination to the product stream, clog the reactor and cause complications in analysis instrumentation. The objective of this research was to perform reduction studies of a mock tar using select catalysts and choose the most effective for primary treatment within the KSC downdraft gasification reactor. Because the KSC reactor is operated at temperatures below typical gasification reactors, this study evaluates catalyst performance below recommended catalytic operating temperatures. The tar reduction experimentation was observed by passing a model tar vapor stream over the catalysts at similar conditions to that of the KSC reactor. Reduction in tar was determined using gas chromatography. Tar reduction efficiency and catalyst performances were evaluated at different temperatures.

  2. Coal-tar-based pavement sealants—a potent source of PAHs

    USGS Publications Warehouse

    Mahler, Barbara J.; Van Metre, Peter C.

    2017-01-01

    P avement sealants are applied to the asphalt pavement of many parking lots, driveways, and even playgrounds in North America (Figure 1), where, when first applied, they render the pavement glossy black and looking like new. Sealant products used commercially in the central, eastern, and northern United States typically are coal-tarbased, whereas those used in the western United States typically are asphalt-based. Although the products look similar, they are chemically different. Coal-tarbased pavement sealants typically are 25-35 percent (by weight) coal tar or coal-tar pitch, materials that are known human carcinogens and that contain high concentrations of polycyclic aromatic hydrocarbons (PAHs) and related chemicals (unless otherwise noted, all Figure 1. Pavement sealant is commonly used to seal parking lots, playgrounds, and driveways throughout the United States. Sealants used in the central, northern, eastern, and southern United States typically contain coal tar or coal-tar pitch, both of which are known human carcinogens. Photos by the U.S. Geological Survey. data in this article are from Mahler et al. 2012 and references therein).

  3. Metal catalysts for steam reforming of tar derived from the gasification of lignocellulosic biomass.

    PubMed

    Li, Dalin; Tamura, Masazumi; Nakagawa, Yoshinao; Tomishige, Keiichi

    2015-02-01

    Biomass gasification is one of the most important technologies for the conversion of biomass to electricity, fuels, and chemicals. The main obstacle preventing the commercial application of this technology is the presence of tar in the product gas. Catalytic reforming of tar appears a promising approach to remove tar and supported metal catalysts are among the most effective catalysts. Nevertheless, improvement of catalytic performances including activity, stability, resistance to coke deposition and aggregation of metal particles, as well as catalyst regenerability is greatly needed. This review focuses on the design and catalysis of supported metal catalysts for the removal of tar in the gasification of biomass. The recent development of metal catalysts including Rh, Ni, Co, and their alloys for steam reforming of biomass tar and tar model compounds is introduced. The role of metal species, support materials, promoters, and their interfaces is described. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. 2008 Weather and Aeolian Sand-Transport Data from the Colorado River Corridor, Grand Canyon, Arizona

    USGS Publications Warehouse

    Draut, Amy E.; Sondossi, Hoda A.; Hazel, Joseph E.; Andrews, Timothy; Fairley, Helen C.; Brown, Christopher R.; Vanaman, Karen M.

    2009-01-01

    This report presents measurements of weather parameters and aeolian (windblown) sand transport made in 2008 near selected archaeological sites in the Colorado River corridor through Grand Canyon, Ariz. The quantitative methods and data discussed here form a basis for monitoring ecosystem processes that affect archeological-site stability. Combined with forthcoming work to evaluate landscape evolution at nearby archaeological sites, these data can be used to document the relationship between physical processes, including weather and aeolian sand transport, and their effects on the physical integrity of archaeological sites. Data collected in 2008 reveal event- and seasonal-scale variations in rainfall, wind, temperature, humidity, and barometric pressure. Broad seasonal changes in aeolian sediment flux are also apparent at most study sites. The continuation of monitoring that began in 2007, and installation of equipment at several new sites in early 2008, allowed evaluation of the effects of the March 2008 high-flow experiment (HFE) on aeolian sand transport. At two of the nine sites studied, spring and summer winds reworked 2008 HFE sandbars to form new aeolian dunes, at which sand moved inland toward larger, well-established dune fields. At the other seven study sites, neither dune formation nor enhanced sand transport after the HFE were observed. At several of those sites, dominant wind directions in spring 2008 were not oriented such that much HFE sand would have moved inland; at other sites, lack of increased inland sand flux is attributable to lack of sandbar enlargement near the study sites or to inhibition of sand movement by vegetation or local topography.

  5. Heterogeneity and loss of soil nutrient elements under aeolian processes in the Otindag Desert, China

    NASA Astrophysics Data System (ADS)

    Li, Danfeng; Wang, Xunming; Lou, Junpeng; Liu, Wenbin; Li, Hui; Ma, Wenyong; Jiao, Linlin

    2018-02-01

    The heterogeneity of the composition of surface soils that are affected by aeolian processes plays important roles in ecological evolution and the occurrence of aeolian desertification in fragile ecological zones, but the associated mechanisms are poorly understood. Using field investigation, wind tunnel experiments, and particle size and element analyses, we discuss the variation in the nutrient elements of surface soils that forms in the presence of aeolian processes of four vegetation species (Caragana microphylla Lam, Artemisia frigida Willd. Sp. Pl., Leymus chinensis (Trin.) Tzvel. and Stipa grandis P. Smirn) growing in the Otindag Desert, China. These four vegetation communities correspond to increasing degrees of degradation. A total of 40 macro elements, trace elements, and oxides were measured in the surface soil and in wind-transported samples. The results showed that under the different degradation stages, the compositions and concentrations of nutrients in surface soils differed for the four vegetation species. Aeolian processes may cause higher heterogeneity and higher loss of soil nutrient elements for the communities of Artemisia frigida Willd. Sp. Pl., Leymus chinensis (Trin.) Tzvel, and Stipa grandis P. Smirn than for the Caragana microphylla Lam community. There was remarkable variation in the loss of nutrients under different aeolian transportation processes. Over the past several decades, the highest loss of soil elements occurred in the 1970s, whereas the loss from 2011 to the present was generally 4.0% of that in the 1970s. These results indicate that the evident decrease in nutrient loss has played an important role in the rehabilitation that has occurred in the region recently.

  6. Continued monitoring of aeolian activity within Herschel Crater, Mars

    NASA Astrophysics Data System (ADS)

    Cardinale, Marco; Pozzobon, Riccardo; Michaels, Timothy; Bourke, Mary C.; Okubo, Chris H.; Chiara Tangari, Anna; Marinangeli, Lucia

    2017-04-01

    In this work, we study a dark dune field on the western side of Herschel crater, a 300 km diameter impact basin located near the Martian equator (14.4°S, 130°E), where the ripple and dune motion reflects the actual atmospheric wind conditions. We develop an integrated analysis using (1) automated ripple mapping that yields ripple orientations and evaluates the spatial variation of actual atmospheric wind conditions within the dunes, (2) an optical cross-correlation that allows us to quantify an average ripple migration rate of 0.42 m per Mars year, and (3) mesoscale climate modeling with which we compare the observed aeolian changes with modeled wind stresses and directions. Our observations are consistent with previous work [1] [2] that detected aeolian activity in the western part of the crater. It also demonstrates that not only are the westerly Herschel dunes movable, but that predominant winds from the north are able to keep the ripples and dunes active within most (if not all) of Herschel crater in the current atmospheric conditions. References: [1] Cardinale, M., Silvestro, S., Vaz, D.A., Michaels, T., Bourke, M.C., Komatsu, G., Marinangeli, L., 2016. Present-day aeolian activity in Herschel Crater, Mars. Icarus 265, 139-148. doi:10.1016/j.icarus.2015.10.022. [2] Runyon, K.D., Bridges, N.T., Ayoub, F., Newman, C.E. and Quade, J.J., 2017. An integrated model for dune morphology and sand fluxes on Mars. Earth and Planetary Science Letters, 457, pp.204-212.

  7. Wet scrubbing of biomass producer gas tars using vegetable oil

    NASA Astrophysics Data System (ADS)

    Bhoi, Prakashbhai Ramabhai

    The overall aims of this research study were to generate novel design data and to develop an equilibrium stage-based thermodynamic model of a vegetable oil based wet scrubbing system for the removal of model tar compounds (benzene, toluene and ethylbenzene) found in biomass producer gas. The specific objectives were to design, fabricate and evaluate a vegetable oil based wet scrubbing system and to optimize the design and operating variables; i.e., packed bed height, vegetable oil type, solvent temperature, and solvent flow rate. The experimental wet packed bed scrubbing system includes a liquid distributor specifically designed to distribute a high viscous vegetable oil uniformly and a mixing section, which was designed to generate a desired concentration of tar compounds in a simulated air stream. A method and calibration protocol of gas chromatography/mass spectroscopy was developed to quantify tar compounds. Experimental data were analyzed statistically using analysis of variance (ANOVA) procedure. Statistical analysis showed that both soybean and canola oils are potential solvents, providing comparable removal efficiency of tar compounds. The experimental height equivalent to a theoretical plate (HETP) was determined as 0.11 m for vegetable oil based scrubbing system. Packed bed height and solvent temperature had highly significant effect (p0.05) effect on the removal of model tar compounds. The packing specific constants, Ch and CP,0, for the Billet and Schultes pressure drop correlation were determined as 2.52 and 2.93, respectively. The equilibrium stage based thermodynamic model predicted the removal efficiency of model tar compounds in the range of 1-6%, 1-4% and 1-2% of experimental data for benzene, toluene and ethylbenzene, respectively, for the solvent temperature of 30° C. The NRTL-PR property model and UNIFAC for estimating binary interaction parameters are recommended for modeling absorption of tar compounds in vegetable oils. Bench scale

  8. Acid Tar Lagoons: Management and Recovery

    NASA Astrophysics Data System (ADS)

    Bohers, Anna; Hroncová, Emília; Ladomerský, Juraj

    2017-04-01

    This contribution presents the issue with possibility of definitive removal of dangerous environmental burden in Slovakia - serious historical problem of two acid tar lagoons. In relation to their removal, no technology has been found so far - technologically and economically suitable, what caused problems with its management. Locality Predajná is well known in Slovakia by its character of contrasts: it is situated in the picturesque landscape of National Park buffer zone of Nízke Tatry, on the other site it is contaminated by 229 211m3 of acid tar with its characteristics of toxicity, carcinogenicity, teratogenicity, mutagenicity and toxicity especially for animals and plants. Acid tar in two landfills with depth of 1m in case of the first lagoon and 9,5m in case of the second lagoon is a waste product derived from operation of Petrochema Dubová - refinery and petrochemical plant whose activity was to process the crude oil through processes of sulfonation and adsorption technology for producing lubricating and special oils, synthetic detergents and special white oils for cosmetic and medical purposes. A part of acid tar was incinerated in two incineration plats. Concentration of SO2 in combustion gases was too high and it was not possible to decrease it under the value of 2000 mg.mn-3 [LADOMERSKÝ, J. - SAMEŠOVÁ, D.: Reduction in sulfur dioxide emissions waste gases of incineration plant. Acta facultatis ecologiae. 1999, p. 217-223]. That is why it was necessary to put them out of operation. Later, because of public opposition it was not possible to build a new incineration plat corresponding to the state of the art. Even though actual Slovak and European legislative for protection of environment against such impacts, neither of tried methods - bio or non-biologic treatment methods - was proved as suitable for processing or for recovery in the reason of different factors admission: i.e. strong aggressivity, difficulty with handling because of its sludgy and

  9. 2009 weather and aeolian sand-transport data from the Colorado River corridor, Grand Canyon, Arizona

    USGS Publications Warehouse

    Draut, Amy E.; Sondossi, Hoda A.; Dealy, Timothy P.; Hazel, Joseph E.; Fairley, Helen C.; Brown, Christopher R.

    2010-01-01

    This report presents measurements of weather parameters and aeolian sand transport made in 2009 near selected archeological sites in the Colorado River corridor through Grand Canyon, Ariz. The quantitative methods and data discussed here form a basis for monitoring ecosystem processes that affect archeological-site stability. Combined with forthcoming work to evaluate landscape evolution at nearby archeological sites, these data can be used to document the relation between physical processes, including weather and aeolian sand transport, and their effects on the physical integrity of archeological sites. Data collected in 2009 reveal event- and seasonal-scale variations in rainfall, wind, temperature, humidity, and barometric pressure. Broad seasonal changes in aeolian sediment flux are also apparent at most study sites. Differences in weather patterns between 2008 and 2009 included an earlier spring windy season, greater spring precipitation even though 2009 annual rainfall totals were in general substantially lower than in 2008, and earlier onset of the reduced diurnal barometric-pressure fluctuations commonly associated with summer monsoon conditions. Weather patterns in middle to late 2009 were apparently affected by a transition of the ENSO cycle from a neutral phase to the El Ni?o phase. The continuation of monitoring that began in 2007, and installation of additional equipment at several new sites in early 2008, allowed evaluation of the effects of the March 2008 high-flow experiment (HFE) on aeolian sand transport. As reported earlier, at 2 of the 9 sites studied, spring and summer winds in 2008 reworked the HFE sandbars to form new aeolian dunes, where sand moved inland toward larger, well-established dune fields. Observations in 2009 showed that farther inland migration of the dune at one of those two sites is likely inhibited by vegetation. At the other location, the new aeolian dune form was found to have moved 10 m inland toward older, well

  10. Laboratory Simulations of Martian and Venusian Aeolian Processes

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    1999-01-01

    The objective of this work was to conduct research in the Planetary Aeolian Facility (PAF) at NASA-Ames Research Center as a laboratory for the planetary science community and to carry-out experiments on the physics and geology of particles moved by winds, and for the development of instruments and spacecraft components for planetary missions.

  11. Porous Carbon Nanofibers from Electrospun Biomass Tar/Polyacrylonitrile/Silver Hybrids as Antimicrobial Materials.

    PubMed

    Song, Kunlin; Wu, Qinglin; Zhang, Zhen; Ren, Suxia; Lei, Tingzhou; Negulescu, Ioan I; Zhang, Quanguo

    2015-07-15

    A novel route to fabricate low-cost porous carbon nanofibers (CNFs) using biomass tar, polyacrylonitrile (PAN), and silver nanoparticles has been demonstrated through electrospinning and subsequent stabilization and carbonization processes. The continuous electrospun nanofibers had average diameters ranging from 392 to 903 nm. The addition of biomass tar resulted in increased fiber diameters, reduced thermal stabilities, and slowed cyclization reactions of PAN in the as-spun nanofibers. After stabilization and carbonization, the resultant CNFs showed more uniformly sized and reduced average diameters (226-507 nm) compared to as-spun nanofibers. The CNFs exhibited high specific surface area (>400 m(2)/g) and microporosity, attributed to the combined effects of phase separations of the tar and PAN and thermal decompositions of tar components. These pore characteristics increased the exposures and contacts of silver nanoparticles to the bacteria including Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, leading to excellent antimicrobial performances of as-spun nanofibers and CNFs. A new strategy is thus provided for utilizing biomass tar as a low-cost precursor to prepare functional CNFs and reduce environmental pollutions associated with direct disposal of tar as an industrial waste.

  12. Optical Properties of Aeolian Dusts Common to West Texas

    USDA-ARS?s Scientific Manuscript database

    Both recent models and historical events such as the Dust Bowl and volcanic eruptions have illustrated aerosols can play a significant role in climate change through direct and indirect optical effects. Soil dust aerosols generated by Aeolian processes represent a significant fraction of the total ...

  13. Estimating tar and nicotine exposure: human smoking versus machine generated smoke yields.

    PubMed

    St Charles, F K; Kabbani, A A; Borgerding, M F

    2010-02-01

    Determine human smoked (HS) cigarette yields of tar and nicotine for smokers using their own brand in their everyday environment. A robust, filter analysis method was used to estimate the tar and nicotine yields for 784 subjects. Seventeen brands were chosen to represent a wide range of styles: 85 and 100 mm lengths; menthol and non-menthol; 17, 23, and 25 mm circumference; with tar yields [Federal Trade Commission (FTC) method] ranging from 1 to 18 mg. Tar bands chosen corresponded to yields of 1-3 mg, 4-6 mg, 7-12 mg, and 13+ mg. A significant difference (p<0.0001) in HS yields of tar and nicotine between tar bands was found. Machine-smoked yields were reasonable predictors of the HS yields for groups of subjects, but the relationship was neither exact nor linear. Neither the FTC, the Massachusetts (MA) nor the Canadian Intensive (CI) machine-smoking methods accurately reflect the HS yields across all brands. The FTC method was closest for the 7-12 mg and 13+ mg products and the MA method was closest for the 1-3mg products. The HS yields for the 4-6 mg products were approximately midway between the FTC and the MA yields. HS nicotine yields corresponded well with published urinary and plasma nicotine biomarker studies. 2009 Elsevier Inc. All rights reserved.

  14. New Insights on Coastal Foredune Growth: The Relative Contributions of Marine and Aeolian Processes

    NASA Astrophysics Data System (ADS)

    Cohn, Nicholas; Ruggiero, Peter; de Vries, Sierd; Kaminsky, George M.

    2018-05-01

    Coastal foredune growth is typically associated with aeolian sediment transport processes, while foredune erosion is associated with destructive marine processes. New data sets collected at a high energy, dissipative beach suggest that total water levels in the collision regime can cause dunes to accrete—requiring a paradigm shift away from considering collisional wave impacts as unconditionally erosional. From morphologic change data sets, it is estimated that marine processes explain between 9% and 38% of annual dune growth with aeolian processes accounting for the remaining 62% to 91%. The largest wind-driven dune growth occurs during the winter, in response to high wind velocities, but out of phase with summertime beach growth via intertidal sandbar welding. The lack of synchronization between maximum beach sediment supply and wind-driven dune growth indicates that aeolian transport at this site is primarily transport, rather than supply, limited, likely due to a lack of fetch limitations.

  15. Sediment grain-size characteristics and relevant correlations to the aeolian environment in China's eastern desert region.

    PubMed

    Zhang, Chunlai; Shen, Yaping; Li, Qing; Jia, Wenru; Li, Jiao; Wang, Xuesong

    2018-06-15

    To identify characteristics of aeolian activity and the aeolian environment in China's eastern desert region, this study collected surface sediment samples from the main desert and sandy lands in this region: the Hobq Desert and the Mu Us, Otindag, Horqin, and Hulunbuir sandy lands. We analyzed the grain-size characteristics and their relationships to three key environmental indicators: drift potential, the dune mobility index, and vegetation cover. The main sediment components are fine to medium sands, with poor (Hulunbuir) to moderate (all other areas) sorting, of unimodal to bimodal distribution. This suggests that improved sorting is accomplished by the loss of both relatively coarser and finer grains. Since 2000, China's eastern desert region has generally experienced low wind energy environmental conditions, resulting in decreased dune activity. In the Hobq Desert, however, the dry climate and sparse vegetation, in conjunction with the most widely distributed mobile dune area in the eastern desert region, have led to frequent and intense aeolian activity, including wind erosion, sand transport, and deposition, resulting in conditions for good sediment sorting. In the Mu Us, Otindag, and Horqin sandy lands, mosaic distribution has resulted from wind erosion-dominated and deposition-dominated aeolian environments. In the Hulunbuir Sandy Land, high precipitation, low temperatures, and steppe vegetation have resulted in well-developed soils; however, strong winds and flat terrain have created an aeolian environment dominated by wind erosion. Copyright © 2018. Published by Elsevier B.V.

  16. 29 CFR 1926.1102 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 8 2014-07-01 2014-07-01 false Coal tar pitch volatiles; interpretation of term. 1926.1102 Section 1926.1102 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH... Hazardous Substances § 1926.1102 Coal tar pitch volatiles; interpretation of term. Note: The requirements...

  17. 29 CFR 1926.1102 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 8 2011-07-01 2011-07-01 false Coal tar pitch volatiles; interpretation of term. 1926.1102 Section 1926.1102 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH... Hazardous Substances § 1926.1102 Coal tar pitch volatiles; interpretation of term. Note: The requirements...

  18. 29 CFR 1926.1102 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 8 2012-07-01 2012-07-01 false Coal tar pitch volatiles; interpretation of term. 1926.1102 Section 1926.1102 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH... Hazardous Substances § 1926.1102 Coal tar pitch volatiles; interpretation of term. Note: The requirements...

  19. 29 CFR 1926.1102 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Coal tar pitch volatiles; interpretation of term. 1926.1102 Section 1926.1102 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH... Hazardous Substances § 1926.1102 Coal tar pitch volatiles; interpretation of term. Note: The requirements...

  20. Aeolian deposition change in the Peruvian central continental shelf during the last millennium and its relationship with atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Briceño, F. J., Sr.; Sifeddine, A.

    2015-12-01

    We present a record of laminated sediment cores retrieved in the Pisco region (14 °S) characterized by local aeolian inputs. This record covers the Medieval Climate Anomaly (MCA) to Little Ice Age (LIA) and the Current Warm Period (CWP) at centennial to sub-decadal resolution. The aim of the study is to reconstruct the patterns of aeolian sedimentation as well as the most important processes that control the input of this material to understand how these components reflect atmospheric climate variability during the last millennium. Assuming that the mineral fraction of the sediment is composed of several lognormally distributed particle populations, we applied an iterative least-square fitting routine to determine the number and the characteristics of the individual particles populations. This allows inferring the spatial and temporal variation of particles populations and thus transport mechanisms involved. Two components with grain size modes at 54±11 μm and 90±11 μm related with local aeolian erosion over the Pisco region were found. Our results showed active aeolian erosion during the second half of the MCA and rapid decrease from the MCA to the LIA. During the LIA the aeolian deposition exhibited a decreasing activity. During the CWP the aeolian deposition increased progressively. Comparison with others South American records indicates that those changes are linked to change in the meridional position of the Intertropical convergence zone (ITCZ) and South Pacific Subtropical High (SPSH) at the centennial time resolution. Finally the CWP period showed an increase in the aeolian deposition and thus in the wind intensity over the past two centuries. This likely represents the result of the modern position of the ITCZ-SPSH system and the associated intensification of the local and regional winds. Nevertheless, the aeolian deposition and in consequence the wind intensity and variability of the last 100 yr are stronger than during the second sequence of the MCA

  1. Repeat ridge jumps associated with plume-ridge interaction, melt transport, and ridge migration

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, Eric; Ito, Garrett; van Hunen, Jeroen

    2011-01-01

    Repeated shifts, or jumps, of mid-ocean ridge segments toward nearby hot spots can produce large, long-term changes to the geometry and location of the tectonic plate boundaries. Ridge jumps associated with hot spot-ridge interaction are likely caused by several processes including shear on the base of the plate due to expanding plume material as well as reheating of lithosphere as magma passes through it to feed off-axis volcanism. To study how these processes influence ridge jumps, we use numerical models to simulate 2-D (in cross section) viscous flow of the mantle, viscoplastic deformation of the lithosphere, and melt migration upward from the asthenospheric melting zone, laterally along the base of the lithosphere, and vertically through the lithosphere. The locations and rates that magma penetrates and heats the lithosphere are controlled by the time-varying accumulation of melt beneath the plate and the depth-averaged lithospheric porosity. We examine the effect of four key parameters: magmatic heating rate of the lithosphere, plate spreading rate, age of the seafloor overlying the plume, and the plume-ridge migration rate. Results indicate that the minimum value of the magmatic heating rate needed to initiate a ridge jump increases with plate age and spreading rate. The time required to complete a ridge jump decreases with larger values of magmatic heating rate, younger plate age, and faster spreading rate. For cases with migrating ridges, models predict a range of behaviors including repeating ridge jumps, much like those exhibited on Earth. Repeating ridge jumps occur at moderate magmatic heating rates and are the result of changes in the hot spot magma flux in response to magma migration along the base of an evolving lithosphere. The tendency of slow spreading to promote ridge jumps could help explain the observed clustering of hot spots near the Mid-Atlantic Ridge. Model results also suggest that magmatic heating may significantly thin the lithosphere

  2. Task 3.9 -- Catalytic tar cracking. Semi-annual report, January 1--June 30, 1995

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

    Young, B.C.; Timpe, R.C.

    1995-12-31

    Tar produced in the gasification of coal is deleterious to the operation of downstream equipment including fuel cells, gas turbines, hot-gas stream cleanup filters, and pressure swing adsorption systems. Catalytic cracking of tars to smaller hydrocarbons can be an effective means to remove these tars from gas streams and, in the process, generate useful products, e.g., methane gas, which is crucial to the operation of molten carbonate fuel cells. The objectives of this project are to investigate whether gasification tars can be cracked by synthetic nickel-substituted micamontmorillonite, zeolite, or dolomite material; and whether the tars can be cracked selectively bymore » these catalysts to produce a desired liquid and/or gas stream. Results to date are presented in the cited papers.« less

  3. Microwave-induced cracking of pyrolytic tars coupled to microwave pyrolysis for syngas production.

    PubMed

    Beneroso, D; Bermúdez, J M; Montes-Morán, M A; Arenillas, A; Menéndez, J A

    2016-10-01

    Herein a new process is proposed to produce a syngas-rich gas fraction (>80vol% H2+CO) from biowaste based on microwave heating within two differentiated steps in order to avoid tars production. The first step consists of the microwave pyrolysis of biowaste induced by a char-based susceptor at 400-800°C; tars, char and syngas-rich gas fractions being produced. The tars are then fed into the second step where a portion of the char from the first step is used as a bed material in a 0.3:1wt% ratio. This bed is heated up by microwaves up to 800°C, allowing thermal cracking of tars and additional syngas (>90vol% H2+CO) being then produced. This new concept arises as an alternative technology to the gasification of biowastes for producing syngas with no need for catalysts or gasifying reagents to minimise tars production. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Investigation of Reversing Sand Dunes at the Bruneau Dunes, Idaho, as Analogs for Features on Mars

    NASA Astrophysics Data System (ADS)

    Zimbelman, J. R.; Scheidt, S. P.

    2012-12-01

    The Bruneau Dunes in south-central Idaho include several large reversing sand dunes located within a cut-off meander of the Snake River. These dunes include the largest single-structured sand dune present in North America. Wind records from the Remote Automated Weather Station (RAWS) installation at the Mountain Home Air Force Base, which is ~21 km NW of the Bruneau Dunes, have proved to be very helpful in assessing the regional wind patterns at this section of the western Snake River Plains province; a bimodal wind regime is present, with seasonal changes of strong (sand-moving) winds blowing from either the northwest or the southeast. During April of 2011, we obtained ten precision topographic surveys across the southernmost reversing dune using a Differential Global Positioning System (DGPS). The DGPS data document the shape of the dune going from a low, broad sand ridge at the southern distal end of the dune to the symmetrically shaped 112-m-high central portion of the dune, where both flanks of the dune consist of active slopes near the angle of repose. These data will be useful in evaluating the reversing dune hypothesis proposed for enigmatic features on Mars called Transverse Aeolian Ridges (TARs), which could have formed either as large mega-ripples or small sand dunes. The symmetric profiles across TARs with heights greater than 1 m are more consistent with measured profiles of reversing sand dunes than with measured profiles of mega-ripples (whose surfaces are coated by large particles ranging from coarse sand to gravel, moved by saltation-induced creep). Using DGPS to monitor changes in the three-dimensional location of the crests of the reversing dunes at the Bruneau Dunes should provide a means for estimating the likely timescale for changes of TAR crests if the Martian features are indeed formed in the same manner as reversing sand dunes on Earth.

  5. Relation Between PAHs and Coal-Tar-Based Pavement Sealant in Urban Environments (Invited)

    NASA Astrophysics Data System (ADS)

    Mahler, B. J.; van Metre, P. C.

    2010-12-01

    Since 2003, coal-tar-based sealant products have come under increased scrutiny as a source of PAHs in urban environments. Sealant (or sealcoat) is the black, shiny substance often applied to asphalt pavement, in particular parking lots and driveways, for esthetic and maintenance purposes. Coal-tar-based sealant, one of the two primary pavement sealant types on the market, typically is 20-35 percent coal-tar pitch, a known carcinogen that is more than 50 percent polycyclic aromatic hydrocarbons (PAHs). The PAH content of the coal-tar-based sealant product is about 1,000 times that of a similar, asphalt-based product, on average. This difference is reflected in regional differences in sealant use and PAH concentrations in pavement dust. In the central and eastern U.S., where the coal-tar-based formulation is prevalent, ΣPAH in mobile particles from sealed pavement have been shown to be about 1,000 times higher than in the western U.S., where the asphalt-based formulation is prevalent (the median ΣPAH concentrations are 2,200 mg/kg in the central and eastern U.S. and 2.1 mg/kg in the western U.S.). Source apportionment modeling indicates that, in the central and eastern U.S., particles from sealed pavement are contributing the majority of the PAHs in recently deposited (post-1990) lake sediment, with implications for ecological health, and that coal-tar-based sealant is the primary cause of upward trends in PAHs in U.S. urban lakes. From the standpoint of human health, research indicates that mobile particles from parking lots with coal-tar-based sealant are tracked indoors, resulting in elevated PAH concentrations in house dust. Coal-tar-based sealcoat being applied to an asphalt parking lot at the University of Texas Pickle Research Center.

  6. 29 CFR 1915.1002 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Coal tar pitch volatiles; interpretation of term. 1915.1002 Section 1915.1002 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH... Toxic and Hazardous Substances § 1915.1002 Coal tar pitch volatiles; interpretation of term. Note: The...

  7. 29 CFR 1915.1002 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Coal tar pitch volatiles; interpretation of term. 1915.1002 Section 1915.1002 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH... Toxic and Hazardous Substances § 1915.1002 Coal tar pitch volatiles; interpretation of term. Note: The...

  8. 29 CFR 1915.1002 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false Coal tar pitch volatiles; interpretation of term. 1915.1002 Section 1915.1002 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH... Toxic and Hazardous Substances § 1915.1002 Coal tar pitch volatiles; interpretation of term. Note: The...

  9. 29 CFR 1915.1002 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Coal tar pitch volatiles; interpretation of term. 1915.1002 Section 1915.1002 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH... Toxic and Hazardous Substances § 1915.1002 Coal tar pitch volatiles; interpretation of term. Note: The...

  10. 29 CFR 1915.1002 - Coal tar pitch volatiles; interpretation of term.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Coal tar pitch volatiles; interpretation of term. 1915.1002 Section 1915.1002 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH... Toxic and Hazardous Substances § 1915.1002 Coal tar pitch volatiles; interpretation of term. Note: The...

  11. Compositional trends in aeolian dust along a transect across the southwestern United States

    USGS Publications Warehouse

    Goldstein, H.L.; Reynolds, R.L.; Reheis, M.C.; Yount, J.C.; Neff, J.C.

    2008-01-01

    Aeolian dust strongly influences ecology and landscape geochemistry over large areas that span several desert ecosystems of the southwestern United States. This study evaluates spatial and temporal variations and trends of the physical and chemical properties of dust in the southwestern United States by examining dust deposited in natural depressions on high isolated surfaces along a transect from the Mojave Desert to the central Colorado Plateau. Aeolian dust is recognized in these depressions on the basis of textural, chemical, isotopic, and mineralogical characteristics and comparisons of those characteristics to the underlying bedrock units. Spatial and temporal trends suggest that although local dust sources are important to the accumulated material in these depressions, Mojave Desert dust sources may also contribute. Depth trends in the depressions suggest that Mojave sources may have contributed more dust to the Colorado Plateau recently than in the past. These interpretations point to the important roles of far-traveled aeolian dust for landscape geochemistry and imply future changes to soil geochemistry under changing conditions in far-distant dust source areas. Copyright 2008 by the American Geophysical Union.

  12. Aeolian nutrient fluxes following wildfire in sagebrush steppe: Implications for soil carbon storage

    USGS Publications Warehouse

    Hasselquist, N.J.; Germino, M.J.; Sankey, J.B.; Ingram, L.J.; Glenn, N.F.

    2011-01-01

    Pulses of aeolian transport following fire can profoundly affect the biogeochemical cycling of nutrients in semi-arid and arid ecosystems. Our objective was to determine horizontal nutrient fluxes occurring in the saltation zone during an episodic pulse of aeolian transport that occurred following a wildfire in a semi-arid sagebrush steppe ecosystem in southern Idaho, USA. We also examined how temporal trends in nutrient fluxes were affected by changes in particle sizes of eroded mass as well as nutrient concentrations associated with different particle size classes. In the burned area, total carbon (C) and nitrogen (N) fluxes were as high as 235 g C m????'1 d????'1 and 19 g N m????'1 d????'1 during the first few months following fire, whereas C and N fluxes were negligible in an adjacent unburned area throughout the study. Temporal variation in C and N fluxes following fire was largely attributable to the redistribution of saltation-sized particles. Total N and organic C concentrations in the soil surface were significantly lower in the burned relative to the unburned area one year after fire. Our results show how an episodic pulse of aeolian transport following fire can affect the spatial distribution of soil C and N, which, in turn, can have important implications for soil C storage. These findings demonstrate how an ecological disturbance can exacerbate a geomorphic process and highlight the need for further research to better understand the role aeolian transport plays in the biogeochemical cycling of C and N in recently burned landscapes. ?? Author(s) 2011. CC Attribution 3.0 License.

  13. Aeolian nutrient fluxes following wildfire in sagebrush steppe: Implications for soil carbon storage

    USGS Publications Warehouse

    Hasselquist, N.J.; Germino, M.J.; Sankey, J.B.; Ingram, L.J.; Glenn, N.F.

    2011-01-01

    Pulses of aeolian transport following fire can profoundly affect the biogeochemical cycling of nutrients in semi-arid and arid ecosystems. Our objective was to determine horizontal nutrient fluxes during an episodic pulse of aeolian transport that occurred following a wildfire in a semi-arid sagebrush steppe ecosystem in southern Idaho, USA. We also examined how temporal trends in nutrient fluxes were affected by changes in particle sizes of eroded mass as well as nutrient concentrations associated with different particle size classes. In the burned area, total carbon (C) and nitrogen (N) fluxes were as high as 235 g C m????'1 d????'1 and 19 g N m????'1 d????'1 during the first few months following fire, whereas C and N fluxes were negligible in an adjacent unburned area throughout the study. Temporal variation in C and N fluxes following fire was largely attributable to the redistribution of saltation-sized particles. Total N and organic C concentrations in the soil surface were significantly lower in the burned relative to the unburned area one year after fire. Our results show how an episodic pulse of aeolian transport following fire can affect the spatial distribution of soil C and N, which, in turn, can have important implications for soil C storage. These findings demonstrate how an ecological disturbance can exacerbate a geomorphic process and highlight the need for further research to better understand the role aeolian transport plays in the biogeochemical cycling of C and N in recently burned landscapes. ?? 2011 Author(s).

  14. Identification of sources of tar balls deposited along the Southwest Caspian Coast, Iran using fingerprinting techniques.

    PubMed

    Shirneshan, Golshan; Bakhtiari, Alireza Riyahi; Memariani, Mahmoud

    2016-10-15

    In 2012, a significant number of tar balls occurred along the Southwest coasts of the Caspian Sea (Iran). Several oil fields of Turkmenistan, Azerbaijan and Iran might be sources of oil spills and lead to the formation of these tar balls. For source identification, 6 tar ball samples were collected from the Southwest beaches of the Caspian Sea and subjected to fingerprint analysis based on the distribution of the source-specific biomarkers of pentacyclic tri-terpanes and steranes. Comparing the diagenic ratios revealed that the tar balls were chemically similar and originated from the same source. Results of double ratio plots (e.g., C29/C30 versus ∑C31-C35/C30 and C28 αββ/(C27 αββ+C29 αββ) versus C29 αββ/(C27 αββ+C28 αββ)) in the tar balls and oils from Iran, Turkmenistan and Azerbaijan indicated that the tar balls might be the result of spills from Turkmenistan oil. Moreover, principle component analysis (PCA) using biomarker ratios on the tar balls and 20 crude oil samples from different wells of Azerbaijan, Iran and Turkmenistan oils showed that the tar balls collected at the Southwest beaches are highly similar to the Turkmenistan oil but one of the Azerbaijan oils (from Bahar field oils) was found to be also slightly close to the tar balls. The weathering characterizations based on the presence of UCM (unresolved complex mixture) and low/high molecular weight ratios (L/H) of alkanes and PAHs indicated the tar ball samples have been significantly influenced by natural weathering processes such as evaporation, photo-degradation and biodegradation. This is the first study of its kind in Iran to use fingerprinting for source identification of tar balls. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. A preliminary source-to-sink sediment budget for aeolian sands

    NASA Astrophysics Data System (ADS)

    Sebe, Krisztina; Csillag, Gábor; Timár, Gábor; Jámbor, Áron

    2015-04-01

    Source-to-sink sediment budgets are being intensively studied in fluvial systems. In contrast, sediment budget calculations are very rare for wind-transported material. This may be attributed to the fact that the exact delineation of both source and sink areas in aeolian systems can pose difficulties. In the Pannonian Basin, aeolian action by northwesterly to northerly winds exerted a thorough impact on landscape evolution during the Quaternary, testified among others by yardangs, wind corridors and numerous ventifacts as well as extensive blown sand fields. Wind erosion has been dated to be important since at least 1.5 Ma ago. Considering the sand fraction, the Pleistocene Pannonian Basin seems to be a nearly complete aeolian sedimentary system from source to sink, thus it provides a good opportunity to carry out sediment budget calculations. The largest blown sand accumulation occupies ~10 000 km2 in the central part of the Pannonian Basin, in the area called Kiskunság, and contains considerable volumes of aeolian sands extending down to the Lower Pleistocene. Its material is traditionally considered to originate from fluvial sediments of the Danube floodplain. However, recent studies on wind erosion and wind direction reconstructions have indicated that a considerable portion of the sand can have had a provenance in the extensive unconsolidated sediments of the Late Miocene Lake Pannon, which cover the uplifting Transdanubian Range and its surroundings. To gain data on this question, we carried out sediment budget calculations to assess if material volumes of the supposed source and sink areas are comparable. In the source area we reconstructed a paleotopography, practically a bounding envelope surface for the Pliocene/Pleistocene boundary using existing knowledge e.g. on the typical succession of Lake Pannon sediments and the evolution history of the area. The missing volume down to the present-day surface was then calculated, where the removed material was

  16. Active aeolian processes on Mars: A regional study in Arabia and Meridiani Terrae

    USGS Publications Warehouse

    Silvestro, S.; Vaz, D.A.; Fenton, L.K.; Geissler, P.E.

    2011-01-01

    We present evidence of widespread aeolian activity in the Arabia Terra/Meridiani region (Mars), where different kinds of aeolian modifications have been detected and classified. Passing from the regional to the local scale, we describe one particular dune field in Meridiani Planum, where two ripple populations are distinguished by means of different migration rates. Moreover, a consistent change in the ripple pattern is accompanied by significant dune advancement (between 0.4-1 meter in one Martian year) that is locally triggered by large avalanche features. This suggests that dune advancement may be common throughout the Martian tropics. ?? 2011 by the American Geophysical Union.

  17. Coal-tar-based pavement sealcoat—Potential concerns for human health and aquatic life

    USGS Publications Warehouse

    Mahler, Barbara J.; Woodside, Michael D.; Van Metre, Peter C.

    2016-04-20

    Aquatic Life Concerns—Runoff from coal-tar-sealcoated pavement, even runoff collected more than 3 months after sealcoat application, is acutely toxic to fathead minnows and water fleas, two species commonly used to assess toxicity to aquatic life. Exposure to even highly diluted runoff from coal-tar-sealcoated pavement can cause DNA damage and impair DNA repair. These findings demonstrate that coal-tar-sealcoat runoff can remain a risk to aquatic life for months after application.

  18. Plume-ridge interaction: Shaping the geometry of mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, Eric L.

    Manifestations of plume-ridge interaction are found across the ocean basins. Currently there are interactions between at least 21 hot spots and nearby ridges along 15--20% of the global mid-ocean ridge network. These interactions produce a number of anomalies including the presence of elevated topography, negative gravity anomalies, and anomalous crustal production. One form of anomalous crustal production is the formation of volcanic lineaments between hotspots and nearby mid-ocean ridges. In addition, observations indicate that mantle plumes tend to "capture" nearby mid-ocean ridges through asymmetric spreading, increased ridge propagation, and discrete shifts of the ridge axis, or ridge jumps. The initiation of ridge jumps and the formation of off-axis volcanic lineaments likely involve similar processes and may be closely related. In the following work, I use theoretical and numerical models to quantify the processes that control the formation of volcanic lineaments (Chapter 2), the initiation of mid-ocean ridge jumps associated with lithospheric heating due to magma passing through the plate (Chapter 3), and the initiation of jumps due to an upwelling mantle plume and magmatic heating governed by melt migration (Chapter 4). Results indicate that lineaments and ridge jumps associated with plume-ridge interaction are most likely to occur on young lithosphere. The shape of lineaments on the seafloor is predicted to be controlled by the pattern of lithospheric stresses associated with a laterally spreading, near-ridge mantle plume. Ridge jumps are likely to occur due to magmatic heating alone only in lithosphere ˜1Myr old, because the heating rate required to jump increases with spreading rate and plate age. The added effect of an upwelling plume introduces competing effects that both promote and inhibit ridge jumps. For models where magmatic heating is controlled by melt migration, repeat ridge jumps are predicted to occur as the plume and ridge separate, but

  19. Catalytic decomposition of tar derived from wood waste pyrolysis using Indonesian low grade iron ore as catalyst

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

    Wicakso, Doni Rahmat; Chemical Engineering Department, Faculty of Engineering, Gadjah Mada University, Jalan Grafika No. 2 Bulaksumur, Yogyakarta, 55281; Sutijan

    Low grade iron ore can be used as an alternative catalyst for bio-tar decomposition. Compared to other catalysts, such as Ni, Rd, Ru, Pd and Pt, iron ore is cheaper. The objective of this research was to investigate the effect of using low grade iron ore as catalyst for tar catalytic decomposition in fixed bed reactor. Tar used in this experiment was pyrolysis product of wood waste while the catalyst was Indonesian low grade iron ore. The variables studied were temperatures between 500 – 600 °C and catalyst weight between 0 – 40 gram. The first step, tar was evaporatedmore » at 450 °C to produce tar vapor. Then, tar vapor was flowed to fixed bed reactor filled low grade iron ore. Gas and tar vapor from reactor was cooled, then the liquid and uncondensable gas were analyzed by GC/MS. The catalyst, after experiment, was weighed to calculate total carbon deposited into catalyst pores. The results showed that the tar components that were heavy and light hydrocarbon were decomposed and cracked within the iron ore pores to from gases, light hydrocarbon (bio-oil) and carbon, thus decreasing content tar in bio-oil and increasing the total gas product. In conclusion, the more low grade iron ore used as catalyst, the tar content in the liquid decrease, the H{sup 2} productivity increased and calorimetric value of bio-oil increased.« less

  20. Anthropogenic initiation and acceleration of aeolian dune activity within the northern European Sand Belt and societal feedbacks over the last 2500 yrs

    NASA Astrophysics Data System (ADS)

    Lungershausen, Uta; Larsen, Annegret; Bork, Hans-Rudolf; Duttmann, Rainer

    2017-04-01

    In North-Western Europe, Pleistocene sand sheets have been re-activated during phases of Holocene deforestation and agricultural land-use. Although there are temporal overlaps between anthropogenic activity and sand sheet re-activation, the root cause and subsequent feedbacks between aeolian activity and societal response remain largely unknown. Here, we seek to establish cause and effect by examining the detailed co-variation in both the timing and magnitude of aeolian and anthropogenic activity through the quantification of Holocene dune sediments in combination with archaeological and pollen records. These records indicate a series of complex phases of aeolian activity followed by landscape stabilization, which we attribute primarily to changing patterns of human impact. We find that a steady increase in dune deposition rates in the Medieval Period corresponds to an increase in settlement activity and deforestation ( 1000-1500 AD). At their peak, Medieval deposition rates were 3.4-times larger than during the late Pleistocene, which was the period experiencing the most favourable natural conditions for aeolian sediment transport in the past 11600 years. Prior to the Medieval Period, relative land-surface stability (depositional hiatus) persisted from the late Pleistocene until the Roman Iron Age Period (0-400 AD), in which deforestation to fuel iron production had a minor impact on aeolian activity, as indicated by the lowest recorded deposition rate (0.12 t/ha/a ± 0.02 t/ha/a). Following the Medieval Period peak in aeolian deposition rates, aeolian activity diminishes rapidly, and coincides with the abandonment of nearby human settlement. This can be interpreted as a direct positive feedback in which Medieval agricultural overexploitation crossed sufficient aeolian activity thresholds to render the landscape practically unworkable for cropping agriculture. Based on our findings and a comprehensive review of Northern European sand belt activity, we interpret a

  1. Measurements of wind, aeolian sand transport, and precipitation in the Colorado River corridor, Grand Canyon, Arizona; January 2005 to January 2006

    USGS Publications Warehouse

    Draut, Amy E.; Rubin, David M.

    2006-01-01

    This report presents measurements of aeolian sediment-transport rates, wind speed and direction, and precipitation records from six locations that contain aeolian deposits in the Colorado River corridor through Grand Canyon, Grand Canyon National Park, Arizona. Aeolian deposits, many of which contain and preserve archaeological material, are an important part of the Grand Canyon ecosystem. This report contains data collected between January 2005 and January 2006, and is the second in a series; the first contained data that were collected between November 2003 and December 2004 (Draut and Rubin, 2005; http://pubs.usgs.gov/of/2005/1309/). Analysis of data collected in 2005 shows great spatial and seasonal variation in wind and precipitation patterns. Total annual rainfall can vary by more than a factor of two over distances ~ 10 km. Western Grand Canyon received substantially more precipitation than the eastern canyon during the abnormally wet winter of 2005. Great spatial variability in precipitation indicates that future sedimentary and geomorphic studies would benefit substantially from continued or expanded data collection at multiple locations along the river corridor, because rainfall records collected by NPS at Phantom Ranch (near river-mile 88) cannot be assumed to apply to other areas of the canyon. Wind velocities and sand transport in 2005 were greatest during May and June, with maximum winds locally as high as ~25 m s-1, and transport rates locally >100 g cm-1 d-1. This represents a later peak in seasonal aeolian sand transport compared to the previous year, in which transport rates were greatest in April and May 2004. Dominant wind direction varies with location, but during the spring windy season the greatest transport potential was directed upstream in Marble Canyon (eastern Grand Canyon). At all locations, rates of sand transport during the spring windy season were 5–15 times higher than at other times of year. This information has been used to

  2. Quantifying postfire aeolian sediment transport using rare earth element tracers

    USGS Publications Warehouse

    Dukes, David; Gonzales, Howell B.; Ravi, Sujith; Grandstaff, David E.; Van Pelt, R. Scott; Li, Junran; Wang, Guan; Sankey, Joel B.

    2018-01-01

    Grasslands, which provide fundamental ecosystem services in many arid and semiarid regions of the world, are undergoing rapid increases in fire activity and are highly susceptible to postfire-accelerated soil erosion by wind. A quantitative assessment of physical processes that integrates fire-wind erosion feedbacks is therefore needed relative to vegetation change, soil biogeochemical cycling, air quality, and landscape evolution. We investigated the applicability of a novel tracer technique—the use of multiple rare earth elements (REE)—to quantify soil transport by wind and to identify sources and sinks of wind-blown sediments in both burned and unburned shrub-grass transition zone in the Chihuahuan Desert, NM, USA. Results indicate that the horizontal mass flux of wind-borne sediment increased approximately threefold following the fire. The REE tracer analysis of wind-borne sediments shows that the source of the horizontal mass flux in the unburned site was derived from bare microsites (88.5%), while in the burned site it was primarily sourced from shrub (42.3%) and bare (39.1%) microsites. Vegetated microsites which were predominantly sinks of aeolian sediments in the unburned areas became sediment sources following the fire. The burned areas showed a spatial homogenization of sediment tracers, highlighting a potential negative feedback on landscape heterogeneity induced by shrub encroachment into grasslands. Though fires are known to increase aeolian sediment transport, accompanying changes in the sources and sinks of wind-borne sediments may influence biogeochemical cycling and land degradation dynamics. Furthermore, our experiment demonstrated that REEs can be used as reliable tracers for field-scale aeolian studies.

  3. Quantifying the provenance of aeolian sediments using multiple composite fingerprints

    NASA Astrophysics Data System (ADS)

    Liu, Benli; Niu, Qinghe; Qu, Jianjun; Zu, Ruiping

    2016-09-01

    We introduce a new fingerprinting method that uses multiple composite fingerprints for studies of aeolian sediment provenance. We used this method to quantify the provenance of sediments on both sides of the Qinghai-Tibetan Railway (QTR) in the Cuona Lake section of the Tibetan Plateau (TP), in an environment characterized by aeolian and fluvial interactions. The method involves repeatedly solving a linear mixing model based on mass conservation; the model is not limited to spatial scale or transport types and uses all the tracer groups that passed the range check, Kruskal-Wallis H-test, and a strict analytical solution screening. The proportional estimates that result from using different composite fingerprints are highly variable; however, the average of these fingerprints has a greater accuracy and certainty than any single fingerprint. The results show that sand from the lake beach, hilly surface, and gullies contribute, respectively, 48%, 31% and 21% to the western railway sediments and 43%, 33% and 24% to the eastern railway sediments. The difference between contributions from various sources on either side of the railway, which may increase in the future, was clearly related to variations in local transport characteristics, a conclusion that is supported by grain size analysis. The construction of the QTR changed the local cycling of materials, and the difference in provenance between the sediments that are separated by the railway reflects the changed sedimentary conditions on either side of the railway. The effectiveness of this method suggests that it will be useful in other studies of aeolian sediments.

  4. Phytotoxicity and Plant Productivity Analysis of Tar-Enriched Biochars

    NASA Astrophysics Data System (ADS)

    Keller, M. L.; Masiello, C. A.; Dugan, B.; Rudgers, J. A.; Capareda, S. C.

    2008-12-01

    Biochar is one of the three by-products obtained by the pyrolysis of organic material, the other two being syngas and bio-oil. The pyrolysis of biomass has generated a great amount of interest in recent years as all three by-products can be put toward beneficial uses. As part of a larger project designed to evaluate the hydrologic impact of biochar soil amendment, we generated a biochar through fast pyrolysis (less than 2 minutes) of sorghum stock at 600°C. In the initial biochar production run, the char bin was not purged with nitrogen. This inadvertent change in pyrolysis conditions produced a fast-pyrolysis biochar enriched with tars. We chose not to discard this batch, however, and instead used it to test the impact of tar-enriched biochars on plants. A suite of phytotoxicity tests were run to assess the effects of tar-rich biochar on plant germination and plant productivity. We designed the experiment to test for negative effects, using an organic carbon and nutrient-rich, greenhouse- optimized potting medium instead of soil. We used Black Seeded Simpson lettuce (Lactuca sativa) as the test organism. We found that even when tars are present within biochar, biochar amendment up to 10% by weight caused increased lettuce germination rates and increased biomass productivity. In this presentation, we will report the statistical significance of our germination and biomass data, as well as present preliminary data on how biochar amendment affects soil hydrologic properties.

  5. Cross-bedding set thickness and stratigraphic architecture of aeolian systems: An example from the Upper Permian Pirambóia Formation (Paraná Basin), southern Brazil

    NASA Astrophysics Data System (ADS)

    Dias, Kayo Delorenzo Nardi; Scherer, Claiton M. S.

    2008-05-01

    The Pirambóia Formation comprises an unconformity-bounded aeolian succession essentially composed of three facies associations: aeolian sand sheet, aeolian dune and interdune facies associations. The lower portion of the Pirambóia Formation is characterised by aeolian sand sheet deposits, which are overlain by aeolian dune and interdune strata, hence pointing to an overall increase in sand availability within the paleoerg. The dune and interdune successions can be further subdivided into two distinct stratigraphic intervals in terms of their mean set thickness. Intervals 1 and 2 display mean set thicknesses of 2.9 and 6.19 m, respectively. This increase in the mean set thickness reflects an increase of the angle of climb and/or dune size. In addition to improve the stratigraphic subdivision, the recognition and correlation of intervals with distinct mean set thicknesses provides a tool for reconstructing aeolian erg architecture from drill cores.

  6. Carbazole is a naturally occurring inhibitor of angiogenesis and inflammation isolated from antipsoriatic coal tar

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

    Jack L. Arbiser; Baskaran Govindarajan; Traci E. Battle

    2006-06-15

    Coal tar is one of the oldest and an effective treatment for psoriasis. Coal tar has been directly applied to the skin, or used in combination with UV light as part of the Goeckerman treatment. The use of coal tar has caused long-term remissions in psoriasis, but has fallen out of favor because the treatment requires hospitalization and coal tar is poorly acceptable aesthetically to patients. Thus, determining the active antipsoriatic component of coal tar is of considerable therapeutic interest. We fractionated coal tar into its components, and tested them using the SVR angiogenesis inhibitor assay. Treatment of SVR endothelialmore » cells with coal tar fractions resulted in the isolation of a single fraction with antiangiogenic activity. The active antiangiogenic compound in coal tar is carbazole. In addition to antiangiogenic activity, carbazole inhibited the production of inflammatory IL-15 by human mononuclear cells. IL-15 is elevated in psoriasis and is thought to contribute to psoriatic inflammation. Carbazole treatment also reduced activity of inducible nitric oxide synthase (iNOS), which is proinflammatory and elevated in psoriasis. The effect of carbazole on upstream pathways in human psoriasis was determined, and carbazole was shown to inhibit signal transducer and activator of transcription (stat)3-mediated transcription, which has been shown to be relevant in human psoriasis. IL-15, iNOS, and stat3 activation require the activation of the small GTPase rac for optimal activity. Carbazole was found to inhibit rac activation as a mechanism for its inhibition of downstream inflammatory and angiogenic pathways. Given its antiangiogenic and anti-inflammatory activities, carbazole is likely a major component of the antipsoriatic activity of coal tar. Carbazole and derivatives may be useful in the therapy of human psoriasis.« less

  7. Reduced tar, nicotine, and carbon monoxide exposure while smoking ultralow- but not low-yield cigarettes

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

    Benowitz, N.L.; Jacob, P. III; Yu, L.

    An unresolved public health issue is whether some modern cigarettes are less hazardous than other and whether patients who cannot stop smoking should be advised to switch to lower-yield cigarettes. The authors studied tar (estimated by urine mutagenicity), nicotine, and carbon monoxide exposure in habitual smokers switched from their usual brand to high- (15 mg of tar), low- (5 mg of tar), or ultralow-yield (1 mg of tar) cigarettes. There were no differences in exposure comparing high- or low-yield cigarettes, but tar and nicotine exposures were reduced by 49% and 56%, respectively, and carbon monoxide exposure by 36% while smokingmore » ultralow-yield cigarettes. Similarly, in 248 subjects smoking their self-selected brand, nicotine intake, estimated by blood concentrations of its metabolite continine, was 40% lower in those who smoked ultralow but no different in those smoking higher yields of cigarettes. The data indicate that ultralow-yield cigarettes do deliver substantial doses of tar, nicotine, and carbon monoxide, but that exposure are considerably less than for other cigarettes.« less

  8. Pollutant sensitivity of the endangered Tar River Spinymussel as assessed by single chemical and effluent toxicity tests

    USGS Publications Warehouse

    Augspurger, Thomas P.; Wang, Ning; Kunz, James L.; Ingersoll, Christopher G.

    2014-01-01

    The federally endangered Tar River spinymussel (Elliptio steinstansana) is endemic to the Tar River and Neuse River systems in North Carolina. The extent to which water quality limits Tar River spinymussels’ recovery is important to establish, and one aspect of that is understanding the species’ pollutant sensitivity. The primary objectives of this study were to 1) develop captive propagation and culture methods for Tar River spinymussels; 2) determine the pollutant sensitivity of captively propagated Tar River spinymussels; 3) examine the utility of the non-endangered yellow lance (Elliptio lanceolata), yellow lampmussel (Lampsilis cariosa) and notched rainbow (Villosa constricta) as surrogates for the Tar River spinymussels’ chemical sensitivity; 4) develop a 7-d method for conducting effluent toxicity tests starting with newly transformed mussels; 5) assess the toxicity of municipal wastewater effluents discharged into the Tar River spinymussels’ current and historic habitat; and, 6) evaluate the protection afforded by existing effluent toxicity test requirements.

  9. Robotic Measurement of Aeolian Processes

    NASA Astrophysics Data System (ADS)

    Roberts, S.; Duperret, J. M.; Jerolmack, D. J.; Lancaster, N.; Nikolich, G.; Shipley, T. F.; Van Pelt, R. S.; Zobeck, T. M.; Koditschek, D. E.

    2015-12-01

    Local and regional measurements of sand transport and dust emission in complex natural settings presently lack spatiotemporal resolution adequate to inform models relevant for land management, climate policy, and the basic science of geomorphology. Deployments of wind, sand and dust sensors sophisticated enough to begin unpacking the complex relations among wind turbulence, surface roughness, sand flux and dust emission remain largely stationary. Aerial observations from satellites, planes and even UAVs help fill in, but none of these modalities offer the hope of "capturing the action" by being at the right place at the right time relative to the highly localized nature of sediment transport during wind storms. We have been developing a legged robot capable of rapidly traversing desert terrain, and are now adapting it to serve as a platform for scientific instrumentation. We aim to field a semi-autonomous, reactive mobile sensory package suited to the needs of aeolian science that can address the limitations of existing alternatives. This presentation reports on early trials in the Jornada LTER and White Sands National Monument aimed at gathering measurements of airflow and rates of sand transport on a dune face, assessing the role of roughness elements such as vegetation in modifying the wind shear stresses incident on the surface, and estimating erosion susceptibility in a natural arid soil. We will solicit ideas from the audience about other potentially interesting and viable measurement targets. Future close collaboration between aeolian, cognitive and robotics scientists such as we hope to promote through this presentation may yield machines with scientifically relevant sensory suites possessing sufficient autonomy to operate in-situ at the most intense episodes of wind and sediment movement under conditions far too uncomfortable and hazardous for human presence.

  10. Effects of human chromosome 12 on interactions between Tat and TAR of human immunodeficiency virus type 1.

    PubMed Central

    Alonso, A; Cujec, T P; Peterlin, B M

    1994-01-01

    Rates of transcriptions of the human immunodeficiency virus are greatly increased by the viral trans activator Tat. In vitro, Tat binds to the 5' bulge of the trans-activation response (TAR) RNA stem-loop, which is present in all viral transcripts. In human cells, the central loop in TAR and its cellular RNA-binding proteins are also critical for the function of Tat. Previously, we demonstrated that in rodent cells (CHO cells), but not in those which contain the human chromosome 12 (CHO12 cells), Tat-TAR interactions are compromised. In this study, we examined the roles of the bulge and loop in TAR in Tat trans activation in these cells. Whereas low levels of trans activation depended solely on interactions between Tat and the bulge in CHO cells, high levels of trans activation depended also on interactions between Tat and the loop in CHO12 cells. Since the TAR loop binding proteins in these two cell lines were identical and different from their human counterpart, the human chromosome 12 does not encode TAR loop binding proteins. In vivo binding competition studies with TAR decoys confirmed that the binding of Tat to TAR is more efficient in CHO12 cells. Thus, the protein(s) encoded on human chromosome 12 helps to tether Tat to TAR via its loop, which results in high levels of trans activation. Images PMID:8083988

  11. Seismicity Pattern Changes before the M = 4.8 Aeolian Archipelago (Italy) Earthquake of August 16, 2010

    PubMed Central

    2014-01-01

    We investigated the seismicity patterns associated with an M = 4.8 earthquake recorded in the Aeolian Archipelago on 16, August, 2010, by means of the region-time-length (RTL) algorithm. This earthquake triggered landslides at Lipari; a rock fall on the flanks of the Vulcano, Lipari, and Salina islands, and some damages to the village of Lipari. The RTL algorithm is widely used for investigating precursory seismicity changes before large and moderate earthquakes. We examined both the spatial and temporal characteristics of seismicity changes in the Aeolian Archipelago region before the M = 4.8 earthquake. The results obtained reveal 6-7 months of seismic quiescence which started about 15 months before the earthquake. The spatial distribution shows an extensive area characterized by seismic quiescence that suggests a relationship between quiescence and the Aeolian Archipelago regional tectonics. PMID:24511288

  12. Influence of cigarette filter ventilation on smokers' mouth level exposure to tar and nicotine.

    PubMed

    Caraway, John W; Ashley, Madeleine; Bowman, Sheri A; Chen, Peter; Errington, Graham; Prasad, Krishna; Nelson, Paul R; Shepperd, Christopher J; Fearon, Ian M

    2017-12-01

    Cigarette filter ventilation allows air to be drawn into the filter, diluting the cigarette smoke. Although machine smoking reveals that toxicant yields are reduced, it does not predict human yields. The objective of this study was to investigate the relationship between cigarette filter ventilation and mouth level exposure (MLE) to tar and nicotine in cigarette smokers. We collated and reviewed data from 11 studies across 9 countries, in studies performed between 2005 and 2013 which contained data on MLE from 156 products with filter ventilation between 0% and 87%. MLE among 7534 participants to tar and nicotine was estimated using the part-filter analysis method from spent filter tips. For each of the countries, MLE to tar and nicotine tended to decrease as filter ventilation increased. Across countries, per-cigarette MLE to tar and nicotine decreased as filter ventilation increased from 0% to 87%. Daily MLE to tar and nicotine also decreased across the range of increasing filter ventilation. These data suggest that on average smokers of highly ventilated cigarettes are exposed to lower amounts of nicotine and tar per cigarette and per day than smokers of cigarettes with lower levels of ventilation. Copyright © 2017 British American Tobacco. Published by Elsevier Inc. All rights reserved.

  13. Impact of genetic variants on haematopoiesis in patients with thrombocytopenia absent radii (TAR) syndrome.

    PubMed

    Manukjan, Georgi; Bösing, Hendrik; Schmugge, Markus; Strauß, Gabriele; Schulze, Harald

    2017-11-01

    Thrombocytopenia absent radii (TAR) syndrome is clearly defined by the combination of radial aplasia and reduced platelet counts. The genetics of TAR syndrome has recently been resolved and comprises a microdeletion on Chromosome 1 including the RBM8A gene and a single nucleotide polymorphism (SNP) either at the 5' untranslated region (5'UTR) or within the first intron of RBM8A. Although phenotypically readily diagnosed after birth, the genetic determination of particular SNPs in TAR syndrome harbours valuable information to evaluate disease severity and treatment decisions. Here, we present clinical data in a cohort of 38 patients and observed that platelet counts in individuals with 5'UTR SNP are significantly lower compared to patients bearing the SNP in intron 1. Moreover, elevated haemoglobin values could only be assessed in patients with 5'UTR SNP whereas white blood cell count is unaffected, indicating that frequently observed anaemia in TAR patients could also be SNP-dependent whereas leucocytosis does not correlate with genetic background. However, this report on a large cohort provides an overview of important haematological characteristics in TAR patients, facilitating evaluation of the various traits in this disease and indicating the importance of genetic validation for TAR syndrome. © 2017 John Wiley & Sons Ltd.

  14. Technology for the production of Zero Q.I pitch from coal tar

    NASA Astrophysics Data System (ADS)

    Karthik, K.; Kumar, K. Rajesh; Rao, C. V. Nageswara; Kumar, B. Vinod; Murty, J. V. S.

    2013-06-01

    Zero Quinoline Insolubles (Q.I) pitch is a special type of pitch obtained from pre-treatment of coal tar, which is converted into pitch. This is used for impregnation of electrodes for improving the strength, electrical properties and also used as a pre-cursor for Mesophase pitch for producing Mesophase pitch based carbon fibers, carbon foam, and Meso carbon micro beads. This paper discusses the technology of Q.I separation from Coal Tar by using decantation of Coal Tar mixed with Heavy Creosote Oil (HC Oil) at different temperatures. By this method we were able to produce the Zero Q.I pitch with a Q.I value of 0.1%.

  15. Creating and maintaining a gas cap in tar sands formations

    DOEpatents

    Vinegar, Harold J.; Karanikas, John Michael; Dinkoruk, Deniz Sumnu; Wellington, Scott Lee

    2010-03-16

    Methods for treating a tar sands formation are disclosed herein. Methods for treating a tar sands formation may include providing heat to at least part of a hydrocarbon layer in the formation from one or more heaters located in the formation. Pressure may be allowed to increase in an upper portion of the formation to provide a gas cap in the upper portion. At least some hydrocarbons are produced from a lower portion of the formation.

  16. Aeolian transport in the field: A comparison of the effects of different surface treatments

    NASA Astrophysics Data System (ADS)

    Dong, Zhibao; Lv, Ping; Zhang, Zhengcai; Qian, Guangqiang; Luo, Wanyin

    2012-05-01

    Aeolian transport represents the result of wind-surface interactions, and therefore depends strongly on variations in the characteristics of the sediment surface. We conducted field observations of aeolian transport of typical dune sand in three 80 m × 80 m plots with different surface treatments: gravel-covered sand, enclosed shifting sand, and open (unprotected) shifting sand. The study was performed at the Shapotou Aeolian Experiment Site in the southeastern part of China's Tengger Desert to compare the effects of these different surface treatments on aeolian transport. To do so, we analyzed the flux density profiles and transport rates above each surface. The flux density profiles for all three treatments followed the exponential decay law that was proposed by most previous researchers to describe the saltation flux density profiles. Coefficients of the exponential decay function were defined as a function of the surface and the wind velocity. The enclosed and open plots with shifting sand had similar flux density profiles, but the flux density above gravel-covered plots showed that transport decayed more slowly with increasing height, producing flux density profiles with a higher average saltation height. The transport rate above the three treatment plots tended to increase proportionally with the cube of the mean wind velocity and with the maximum wind velocity during the observation period, but was more strongly correlated with the square of drift potential. Transport rates above the plot with open shifting sand were greater than those above the plots with enclosed shifting sand and the gravel-covered plot.

  17. Adhesion and abrasion of surface materials in the Venusian aeolian environment

    NASA Technical Reports Server (NTRS)

    Marshall, John R.; Greeley, Ronald; Tucker, David; Fogleman, Guy; Hixon, Raymond

    1991-01-01

    In laboratory simulations of the Venusian environment, rock and mineral 'target' surfaces struck by aeolian particles develop a thin layer of accretionary material derived from the particles' attrition debris. Accretion may be (in part) a manifestation of 'cold welding', a process well known in engineering, where bonding occurs between metals at a tribological interface. Accretion on geological materials was found to occur at all Venusian surface temperatures and for all types of materials tested. First-order variations in the amount deposited by particles are related to relative attrition susceptibilities. Second-order variations relate to properties of the particle-target interface. Variations in accretion volume are apparently independent of mineral chemistry and are only weakly dependent on crystallography. The results suggest that accretion should be a fairly universal phenomenon in areas of Venus subject to aeolian activity.

  18. Exosomes from HIV-1-infected Cells Stimulate Production of Pro-inflammatory Cytokines through Trans-activating Response (TAR) RNA*

    PubMed Central

    Sampey, Gavin C.; Saifuddin, Mohammed; Schwab, Angela; Barclay, Robert; Punya, Shreya; Chung, Myung-Chul; Hakami, Ramin M.; Asad Zadeh, Mohammad; Lepene, Benjamin; Klase, Zachary A.; El-Hage, Nazira; Young, Mary; Iordanskiy, Sergey; Kashanchi, Fatah

    2016-01-01

    HIV-1 infection results in a chronic illness because long-term highly active antiretroviral therapy can lower viral titers to an undetectable level. However, discontinuation of therapy rapidly increases virus burden. Moreover, patients under highly active antiretroviral therapy frequently develop various metabolic disorders, neurocognitive abnormalities, and cardiovascular diseases. We have previously shown that exosomes containing trans-activating response (TAR) element RNA enhance susceptibility of undifferentiated naive cells to HIV-1 infection. This study indicates that exosomes from HIV-1-infected primary cells are highly abundant with TAR RNA as detected by RT-real time PCR. Interestingly, up to a million copies of TAR RNA/μl were also detected in the serum from HIV-1-infected humanized mice suggesting that TAR RNA may be stable in vivo. Incubation of exosomes from HIV-1-infected cells with primary macrophages resulted in a dramatic increase of proinflammatory cytokines, IL-6 and TNF-β, indicating that exosomes containing TAR RNA could play a direct role in control of cytokine gene expression. The intact TAR molecule was able to bind to PKR and TLR3 effectively, whereas the 5′ and 3′ stems (TAR microRNAs) bound best to TLR7 and -8 and none to PKR. Binding of TAR to PKR did not result in its phosphorylation, and therefore, TAR may be a dominant negative decoy molecule in cells. The TLR binding through either TAR RNA or TAR microRNA potentially can activate the NF-κB pathway and regulate cytokine expression. Collectively, these results imply that exosomes containing TAR RNA could directly affect the proinflammatory cytokine gene expression and may explain a possible mechanism of inflammation observed in HIV-1-infected patients under cART. PMID:26553869

  19. Physicochemical Approaches for the Remediation of Former Manufactured Gas Plant Tars

    NASA Astrophysics Data System (ADS)

    Hauswirth, S.; Miller, C. T.

    2014-12-01

    Former manufactured gas plant (FMGP) tars are one of the most challenging non-aqueous phase liquid (NAPL) contaminants to remediate due to their complex chemical composition, high viscosities, and ability to alter wettability. In this work, we investigate several in situ remediation techniques for the removal of tar from porous media. Batch and column experiments were conducted to test the effectiveness of mobilization, solubilization, and chemical oxidation remediation approaches. Alkaline (NaOH), surfactant (Triton X-100), and polymer (xanthan gum) agents were used in various combinations to reduce tar-water interfacial tension, increase flushing solution viscosity, and increase the solubilities of tar components. Base-activated sodium persulfate was used alone and in combination with surfactant to chemically oxidized tar components. The effectiveness of each method was assessed in terms of both removal of PAHs from the system and reduction of dissolved-phase effluent polycyclic aromatic hydrocarbon (PAH) concentrations. In column studies, alkaline-polymer (AP) and alkaline-surfactant-polymer (ASP) solutions efficiently mobilized 81-93% and 95-96% of residual PAHs, respectively, within two pore volumes. The impact of AP flushing on dissolved-phase PAH concentrations was relatively low; however, the concentrations of several low molar mass PAHs were significantly reduced after ASP flushing. Surfactant-polymer (SP) solutions removed over 99% of residual PAHs through a combination of mobilization and solubilization, and reduced the post-remediation, dissolved-phase total PAH concentration by 98.4-99.1%. Degradation of residual PAHs by base-activated sodium persulfate was relatively low (30-50%), and had little impact on dissolved-phase PAH concentrations.

  20. Thermal Cracking of Tars in a Continuously Fed Reactor with Steam

    DTIC Science & Technology

    2011-05-01

    Fluidized Bed using biomass 8 Tars  Mixture of organic components present in gasification product gas with high molecular weight hydrocarbons [MW...Disable sulfur removal systems FoulingPlugging [Ref. 3: Biomass Gasification – Tar and Particles in Product Gases Sampling and Analysis”, European...P., and Nussbaumer T., “Gas Cleaning Requirements for Internal Combustion Engine Applications of Fixed Bed Biomass Gasification ”, Biomass and

  1. Cold Preparation of Heroin in a Black Tar Market.

    PubMed

    Roth, Alexis M; Armenta, Richard F; Wagner, Karla D; Strathdee, Steffanie A; Goldshear, Jesse L; Cuevas-Mota, Jazmine; Garfein, Richard S

    2017-07-29

    Black tar heroin is typically prepared for injection with heat which decreases the risk of HIV transmission by inactivating the virus. We received reports that persons who inject drugs (PWID) in Tijuana, Baja California, Mexico, a black tar heroin market, were using only water to dissolve heroin. Because Tijuana abuts San Diego County, CA, United States, we undertook the present analyses to determine the prevalence of this practice among PWID in San Diego, California. PWID completed quarterly behavioral assessments and serological testing for blood-borne viruses. Bivariate and multivariable logistic regression models were constructed to assess for individual, social, and structural correlates of preparing heroin without heat within the preceding 6 months. Nearly half of black tar heroin users (149/305) reported they had prepared heroin without heat within 6 months. In multivariable analysis, cold preparation was independently associated with younger age (10 year decrease; AOR = 1.25; 95% CI 1.03, 1.53), more drug injecting acquaintances (per 5 acquaintance increase; AOR = 1.05; 95% CI 1.01, 1.09) and prefilled syringe use (injecting drugs from syringes that are already filled with drugs before purchase; AOR = 1.86; 95% CI 1.14, 3.02). Conclusions/Importance: To our knowledge, this is the first paper to report that PWID living in a black tar heroin market are preparing heroin without heat. Additional research is needed to determine whether this is an endemic practice or PWID are engaging in new forms of drug preparation in response to changes in the environment.

  2. The Auxin Biosynthetic TRYPTOPHAN AMINOTRANSFERASE RELATED TaTAR2.1-3A Increases Grain Yield of Wheat.

    PubMed

    Shao, An; Ma, Wenying; Zhao, Xueqiang; Hu, Mengyun; He, Xue; Teng, Wan; Li, Hui; Tong, Yiping

    2017-08-01

    Controlling the major auxin biosynthetic pathway to manipulate auxin content could be a target for genetic engineering of crops with desired traits, but little progress had been made because low or high auxin contents often cause developmental inhibition. Here, we performed a genome-wide analysis of bread wheat ( Triticum aestivum ) to identify the Tryptophan Aminotransferase of Arabidopsis1/Tryptophan Aminotransferase-Related (TAA1/TAR) genes that function in the tryptophan-dependent pathway of auxin biosynthesis. Sequence mining together with gene cloning identified 15 TaTAR genes, among which 12 and three genes were phylogenetically close to Arabidopsis ( Arabidopsis thaliana ) AtTAR2 and AtTAR3, respectively. TaTAR2.1 had the most abundant transcripts in the TaTAR2 genes and was expressed mainly in roots and up-regulated by low nitrogen (N) availability. Knockdown of TaTAR2.1 caused vegetative and reproductive deficiencies and impaired lateral root (LR) growth under both high- and low-N conditions. Overexpressing TaTAR2.1-3A in wheat enhanced LR branching, plant height, spike number, grain yield, and aerial N accumulation under different N supply levels. In addition, overexpressing TaTAR2.1-3A in Arabidopsis elevated auxin accumulation in the primary root tip, LR tip, LR primordia, and cotyledon and hypocotyl and increased primary root length, visible LR number, and shoot fresh weight under high- and low-N conditions. Our results indicate that TaTAR2.1 is critical for wheat growth and also shows potential for genetic engineering to reach the aim of improving the grain yield of wheat. © 2017 American Society of Plant Biologists. All Rights Reserved.

  3. Use of mineral oil Fleet enema for the removal of a large tar burn: a case report.

    PubMed

    Carta, Tricia; Gawaziuk, Justin; Liu, Song; Logsetty, Sarvesh

    2015-03-01

    Extensive hot tar burns are relatively uncommon. Management of these burns provides a significant clinical challenge especially with respect to tar removal involving a large total body surface area (TBSA), without causing further tissue injury. We report a case of an over 40-year old male construction worker who was removing a malfunctioning cap from broken valve. This resulted in tar spraying over the anterior surface of his body including legs, feet, chest, abdomen, arms, face and oral cavity (80% TBSA covered in tar resulting in a 50% TBSA burn injury). Initially, petrolatum-based, double antibiotic ointment was used to remove the tar, based on our previous experience with small tar burns. However, this was time-consuming and ineffective. The tar was easily removed with mineral oil without irritation. In order to meet the demand for quantity of mineral oil, the pharmacy suggested using mineral oil Fleet enema (C.B. Fleet Company, Inc., Lynchburg, Virginia, USA). The squeezable bottle and catheter tip facilitated administration of oil into the patient's construction boots and under clothing that was adhered to the patient's skin. Tar removal requires an effective, non-toxic and non-irritating agent. Mineral oil is such an agent. For patients that may present with a large surface area tar burn, using mineral oil Fleet enema is a viable option that facilitates application into difficult areas. Grant Support: The Firefighters' Burn Fund (Manitoba) supported this project. Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.

  4. Aeolian sand transport over complex intertidal bar-trough beach topography

    NASA Astrophysics Data System (ADS)

    Anthony, Edward J.; Ruz, Marie-Hélène; Vanhée, Stéphane

    2009-04-01

    Aeolian sand transport on macrotidal beaches with complex intertidal bar-trough topography (ridge-and-runnel beaches) was assessed from experiments in northern France that involved measurements of wind speed, saltation, surface moisture contents, and rates of sand trapping across surveyed portions of the upper beach profile. Beaches exhibiting intertidal bars and troughs are much more complex, topographically, than simple reflective or dissipative beaches. Furthermore, the intertidal bar-trough morphology commonly exhibits strong cross-shore variations in the moisture contents of the beach surface and in patterns of bedform development. The results of four 30-minute experiments, conducted along topographically surveyed portions of the upper beach-dune toe profile, show that troughs act as extremely efficient sand interceptors, because of their permanently saturated state, which also inhibits sand mobilisation. Troughs, thus, limit or segment the dry fetch during conditions of intermittent saltation. Flow lines, inferred from the wind profiles, suggest that complex interactions at the boundary layer are generated by the bar-trough topography. Troughs systematically appear to be characterised by air expansion, while bar faces generate ramp wind acceleration for onshore winds, and sometimes immediate downwind deceleration for offshore winds. These effects may also contribute to cross-shore variations in the rates of sand trapping. Finally, a simple conceptual model of effective fetch development, integrating the effects of the spring-neap tidal range and of gross bar-trough morphological variability over time, is proposed for bar-trough beaches. The model highlights the key theme of fetch segmentation induced by cross-shore differentiation in the moisture contents of the beach surface hinged on the complex topography of multiple bars and troughs.

  5. Partitioning studies of coal-tar constituents in a two-phase contaminated ground-water system

    USGS Publications Warehouse

    Rostad, C.E.; Pereira, W.E.; Hult, M.F.

    1985-01-01

    Organic compounds derived from coal-tar wastes in a contaminated aquifer in St. Louis Park, Minnesota, were identified, and their partition coefficients between the tar phase and aqueous phase were determined and compared with the corresponding n-octanol/water partition coefficients. Coal tar contains numerous polycyclic aromatic compounds, many of which are suspected carcinogens or mutagens. Groundwater contamination by these toxic compounds may pose an environmental health hazard in nearby public water-supply wells. Fluid samples from this aquifer developed two phases upon settling: an upper aqueous phase, and a lower oily-tar phase. After separating the phases, polycyclic aromatic compounds in each phase were isolated using complexation with N-methyl-2-pyrrolidone and identified by fused-silica capillary gas chromatography/mass spectrometry. Thirty-one of the polycyclic aromatic compounds were chosen for further study from four different classes: 12 polycyclic aromatic hydrocarbons, 10 nitrogen heterocycles, 5 sulfur heterocycles, and 4 oxygen heterocycles. Within each compound class, the tar/water partition coefficients of these compounds were reasonably comparable with the respective n-octanol/water partition coefficient.

  6. Aeolian stratigraphy describes ice-age paleoenvironments in unglaciated Arctic Alaska

    NASA Astrophysics Data System (ADS)

    Gaglioti, Benjamin V.; Mann, Daniel H.; Groves, Pamela; Kunz, Michael L.; Farquharson, Louise M.; Reanier, Richard E.; Jones, Benjamin M.; Wooller, Matthew J.

    2018-02-01

    Terrestrial paleoenvironmental records with high dating resolution extending into the last ice age are rare from the western Arctic. Such records can test the synchronicity and extent of ice-age climatic events and define how Arctic landscapes respond to rapid climate changes. Here we describe the stratigraphy and sedimentology of a yedoma deposit in Arctic Alaska (the Carter Section) dating to between 37,000 and 9000 calibrated radiocarbon years BP (37-9 ka) and containing detailed records of loess and sand-sheet sedimentation, soil development, carbon storage, and permafrost dynamics. Alternation between sand-sheet and loess deposition provides a proxy for the extent and activity of the Ikpikpuk Sand Sea (ISS), a large dune field located immediately upwind. Warm, moist interstadial times (ca. 37, 36.3-32.5, and 15-13 ka) triggered floodplain aggradation, permafrost thaw, reduced loess deposition, increased vegetation cover, and rapid soil development accompanied by enhanced carbon storage. During the Last Glacial Maximum (LGM, ca. 28-18 ka), rapid loess deposition took place on a landscape where vegetation was sparse and non-woody. The most intense aeolian activity occurred after the LGM between ca. 18 and 15 ka when sand sheets fringing the ISS expanded over the site, possibly in response to increasingly droughty conditions as summers warmed and active layers deepened. With the exception of this lagged LGM response, the record of aeolian activity at the Carter Section correlates with other paleoenvironmental records from unglaciated Siberia and Alaska. Overall, rapid shifts in geomorphology, soils, vegetation, and permafrost portray an ice-age landscape where, in contrast to the Holocene, environmental change was chronic and dominated by aeolian processes.

  7. Applicability of Unmanned Aerial Vehicles in Research on Aeolian Processes

    NASA Astrophysics Data System (ADS)

    Algimantas, Česnulevičius; Artūras, Bautrėnas; Linas, Bevainis; Donatas, Ovodas; Kęstutis, Papšys

    2018-02-01

    Surface dynamics and instabilities are characteristic of aeolian formation. The method of surface comparison is regarded as the most appropriate one for evaluation of the intensity of aeolian processes and the amount of transported sand. The data for surface comparison can be collected by topographic survey measurements and using unmanned aerial vehicles. Time cost for relief microform fixation and measurement executing topographic survey are very high. The method of unmanned aircraft aerial photographs fixation also encounters difficulties because there are no stable clear objects and contours that enable to link aerial photographs, to determine the boundaries of captured territory and to ensure the accuracy of surface measurements. Creation of stationary anchor points is irrational due to intense sand accumulation and deflation in different climate seasons. In September 2015 and in April 2016 the combined methodology was applied for evaluation of intensity of aeolian processes in the Curonian Spit. Temporary signs (marks) were installed on the surface, coordinates of the marks were fixed using GPS and then flight of unmanned aircraft was conducted. The fixed coordinates of marks ensure the accuracy of measuring aerial imagery and the ability to calculate the possible corrections. This method was used to track and measure very small (micro-rank) relief forms (5-10 cm height and 10-20 cm length). Using this method morphometric indicators of micro-terraces caused by sand dunes pressure to gytia layer were measured in a non-contact way. An additional advantage of the method is the ability to accurately link the repeated measurements. The comparison of 3D terrain models showed sand deflation and accumulation areas and quantitative changes in the terrain very clearly.

  8. Vegetation in drylands: Effects on wind flow and aeolian sediment transport

    USDA-ARS?s Scientific Manuscript database

    Drylands are characterised by patchy vegetation, erodible surfaces and erosive aeolian processes. Empirical and modelling studies have shown that vegetation elements provide drag on the overlying airflow, thus affecting wind velocity profiles and altering erosive dynamics on desert surfaces. However...

  9. Vegetation and substrate properties of aeolian dune fields in the Colorado River corridor, Grand Canyon, Arizona

    USGS Publications Warehouse

    Draut, Amy E.

    2011-01-01

    This report summarizes vegetation and substrate properties of aeolian landscapes in the Colorado River corridor through Grand Canyon, Arizona, in Grand Canyon National Park. Characterizing these parameters provides a basis from which to assess future changes in this ecosystem, including the spread of nonnative plant species. Differences are apparent between aeolian dune fields that are downwind of where modern controlled flooding deposits new sandbars (modern-fluvial-sourced dune fields) and those that have received little or no new windblown sand since river regulation began in the 1960s (relict-fluvial-sourced dune fields). The most substantial difference between modern- and relict-fluvial-sourced aeolian dune fields is the greater abundance of biologic soil crust in relict dune fields. These findings can be used with similar investigations in other geomorphic settings in Grand Canyon and elsewhere in the Colorado River corridor to evaluate the health of the Colorado River ecosystem over time.

  10. Hotspot-Ridge Interaction: Shaping the Geometry of Mid-Ocean Ridges

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, E.; Ito, G.

    2004-12-01

    Surface manifestations of hotspot-ridge interaction include geochemical anomalies, elevated ridge topography, negative gravity anomalies, off-axis volcanic lineaments, and ridge reorganization events. The last of these is expressed as either "captured" ridge segments due to asymmetric spreading, such as at the Galapagos, or as discrete jumps of the ridge axis toward the hotspot, such as at the Iceland, Tristan de Cuhna, Discovery, Shona, Louisville, Kerguelen, and Reunion hotspots. Mid-ocean ridge axis reorganizations through discrete jumps will cause variations in local volcanic patterns, lead to changes in overall plate shape and ridge axis morphology, and alter local mantle flow patterns. It has been proposed that discrete ridge jumps are a product of interaction between the lithosphere and a mantle plume. We examine this hypothesis using thin plate theory coupled with continuum damage mechanics to calculate the two-dimensional (plan-view) pattern of depth-integrated stresses in a plate of varying thickness with weakening due to volcanism at the ridge and above the plume center. Forces on the plate include plume shear, plate parallel gravitational forces due to buoyant uplift, and a prescribed velocity of plate motion along the edges of the model. We explore these forces and the effect of damage as mechanisms that may be required to predict ridge jumps.

  11. The composition of Martian aeolian sands: Thermal emissivity from Viking IRTM observations

    NASA Technical Reports Server (NTRS)

    Edgett, Kenneth S.; Christensen, Philip R.

    1992-01-01

    Aeolian sands provide excellent surfaces for the remote determination of the mineralogic composition of Martian materials, because such deposits consist of relatively well-sorted, uniform particle sizes and might consist of chemically unaltered, primary mineral grains derived from bedrock. Dark features on the floors of Martian craters are controlled by aeolian processes and many consist largely of unconsolidated, windblown sand. Measurement of the thermal emissivity of geologic materials provides a way to identify mid-infrared absorption bands, the strength and positions of which vary with mineral structure and composition. The Viking Infrared Thermal Mapper (IRTM) had four surface-sensing mid-IR bands, three of which, the 7, 9, and 11 micron channels, correspond to absorption features characteristic of carbonates, sialic, and mafic minerals, respectively. In this study, the highest quality IRTM data were constrained so as to avoid the effects of atmospheric dust, clouds, surface frosts, and particle size variations (the latter using data obtained between 7 and 9 H, and they were selected for dark intracrater features such that only data taken directly from the dark feature were used, so as to avoid thermal contributions from adjacent but unrelated materials. Three-point emissivity spectra of Martian dart intracrater features were compared with laboratory emission spectra of minerals and terrestrial aeolian sands convolved using the IRTM response function to the four IRTM spectral channels.

  12. A photographic method for estimating wear of coal tar sealcoat from parking lots

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

    Mateo Scoggins; Tom Ennis; Nathan Parker

    2009-07-01

    Coal-tar-based sealcoat has been recognized as an important source of PAHs to the environment through wear and transport via stormwater runoff. Sealcoat removal rates have not been measured or even estimated in the literature due to the complex array of physical and chemical process involved. A photographic study was conducted that incorporates all sources of wear using 10 coal tar-sealed parking lots in Austin, Texas, with sealcoat age ranging from 0 to 5 years. Randomly located photographs from each parking lot were analyzed digitally to quantify black sealed areas versus lighter colored unsealed areas at the pixel level. The resultsmore » indicate that coal tar sealcoat wears off of the driving areas of parking lots at a rate of approximately 4.7% per year, and from the parking areas of the lots at a rate of approximately 1.4% per year. The overall annual loss of sealcoat was calculated at 2.4%. This results in an annual delivery to the environment of 0.51 g of PAHs per m{sup 2} of coal tar-sealed parking lot. These values provide a more robust and much higher estimate of loading of PAHs from coal tar sealcoated parking lots when compared to other available measures. 20 refs., 6 figs.« less

  13. TarPmiR: a new approach for microRNA target site prediction.

    PubMed

    Ding, Jun; Li, Xiaoman; Hu, Haiyan

    2016-09-15

    The identification of microRNA (miRNA) target sites is fundamentally important for studying gene regulation. There are dozens of computational methods available for miRNA target site prediction. Despite their existence, we still cannot reliably identify miRNA target sites, partially due to our limited understanding of the characteristics of miRNA target sites. The recently published CLASH (crosslinking ligation and sequencing of hybrids) data provide an unprecedented opportunity to study the characteristics of miRNA target sites and improve miRNA target site prediction methods. Applying four different machine learning approaches to the CLASH data, we identified seven new features of miRNA target sites. Combining these new features with those commonly used by existing miRNA target prediction algorithms, we developed an approach called TarPmiR for miRNA target site prediction. Testing on two human and one mouse non-CLASH datasets, we showed that TarPmiR predicted more than 74.2% of true miRNA target sites in each dataset. Compared with three existing approaches, we demonstrated that TarPmiR is superior to these existing approaches in terms of better recall and better precision. The TarPmiR software is freely available at http://hulab.ucf.edu/research/projects/miRNA/TarPmiR/ CONTACTS: haihu@cs.ucf.edu or xiaoman@mail.ucf.edu Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press.

  14. Tar analysis from biomass gasification by means of online fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Baumhakl, Christoph; Karellas, Sotirios

    2011-07-01

    Optical methods in gas analysis are very valuable mainly due to their non-intrusive character. That gives the possibility to use them for in-situ or online measurements with only optical intervention in the measurement volume. In processes like the gasification of biomass, it is of high importance to monitor the gas quality in order to use the product gas in proper machines for energy production following the restrictions in the gas composition but also improving its quality, which leads to high efficient systems. One of the main problems in the biomass gasification process is the formation of tars. These higher hydrocarbons can lead to problems in the operation of the energy system. Up to date, the state of the art method used widely for the determination of tars is a standardized offline measurement system, the so-called "Tar Protocol". The aim of this work is to describe an innovative, online, optical method for determining the tar content of the product gas by means of fluorescence spectroscopy. This method uses optical sources and detectors that can be found in the market at low cost and therefore it is very attractive, especially for industrial applications where cost efficiency followed by medium to high precision are of high importance.

  15. Modeling the impact of bubbling bed hydrodynamics on tar yield and its fluctuations during biomass fast pyrolysis

    DOE PAGES

    Xiong, Qingang; Ramirez, Emilio; Pannala, Sreekanth; ...

    2015-10-09

    The impact of bubbling bed hydrodynamics on temporal variations in the exit tar yield for biomass fast pyrolysis was investigated using computational simulations of an experimental laboratory-scale reactor. A multi-fluid computational fluid dynamics model was employed to simulate the differential conservation equations in the reactor, and this was combined with a multi-component, multi-step pyrolysis kinetics scheme for biomass to account for chemical reactions. The predicted mean tar yields at the reactor exit appear to match corresponding experimental observations. Parametric studies predicted that increasing the fluidization velocity should improve the mean tar yield but increase its temporal variations. Increases in themore » mean tar yield coincide with reducing the diameter of sand particles or increasing the initial sand bed height. However, trends in tar yield variability are more complex than the trends in mean yield. The standard deviation in tar yield reaches a maximum with changes in sand particle size. As a result, the standard deviation in tar yield increases with the increases in initial bed height in freely bubbling state, while reaches a maximum in slugging state.« less

  16. Skin cancer in patients with psoriasis treated with coal tar. A 25-year follow-up study

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

    Pittelkow, M.R.; Perry, H.O.; Muller, S.A.

    1981-08-01

    For many years, crude coal tar has been used for the treatment of psoriasis. The possible carcinogenic effect of crude coal tar and ultraviolet (UV) radiation (Goeckerman regimen), considered individually or in combination, has been of some concern to physicians. A 25-year follow-up study was completed on 280 patients with psoriasis who were hospitalized and treated with crude coal tar and UV radiation at the Mayo Clinic, Rochester, Minn, during the years 1950 through 1954. The results of this study suggest that the incidence of skin cancer is not appreciably increased above the expected incidence for the general population whenmore » patients are treated with coal tar ointments. It seems that the Goeckerman regimen (topical crude coal tar combined with UV radiation) can be used with minimal risk for skin cancer in the treatment of psoriasis.« less

  17. Volatilization of polycyclic aromatic hydrocarbons from coal-tar-sealed pavement

    USGS Publications Warehouse

    Van Metre, Peter C.; Majewski, Michael S.; Mahler, Barbara J.; Foreman, William T.; Braun, Christopher L.; Wilson, Jennifer T.; Burbank, Teresa L.

    2012-01-01

    Coal-tar-based pavement sealants, a major source of PAHs to urban water bodies, are a potential source of volatile PAHs to the atmosphere. An initial assessment of volatilization of PAHs from coal-tar-sealed pavement is presented here in which we measured summertime gas-phase PAH concentrations 0.03 m and 1.28 m above the pavement surface of seven sealed (six with coal-tar-based sealant and one with asphalt-based sealant) and three unsealed (two asphalt and one concrete) parking lots in central Texas. PAHs also were measured in parking lot dust. The geometric mean concentration of the sum of eight frequently detected PAHs (ΣPAH8) in the 0.03-m samples above sealed lots (1320 ng m-3) during the hottest part of the day was 20 times greater than that above unsealed lots (66.5 ng m-3). The geometric mean concentration in the 1.28-m samples above sealed lots (138 ng m-3) was five times greater than above unsealed lots (26.0 ng m-3). Estimated PAH flux from the sealed lots was 60 times greater than that from unsealed lots (geometric means of 88 and 1.4 μg m-2 h-1, respectively). Although the data set presented here is small, the much higher estimated fluxes from sealed pavement than from unsealed pavement indicate that coal-tar-based sealants are emitting PAHs to urban air at high rates compared to other paved surfaces.

  18. Alluvial Fans on Dunes in Kaiser Crater Suggest Niveo-Aeolian and Denivation Processes on Mars

    NASA Technical Reports Server (NTRS)

    Bourke, M. C.

    2005-01-01

    On Earth, cold region sand dunes often contain inter-bedded sand, snow, and ice. These mixed deposits of wind-driven snow, sand, silt, vegetal debris, or other detritus have been termed Niveo-aeolian deposits. These deposits are often coupled with features that are due to melting or sublimation of snow, called denivation features. Snow and ice may be incorporated into dunes on Mars in three ways. Diffusion of water vapour into pore spaces is the widely accepted mechanism for the accretion of premafrost ice. Additional mechanisms may include the burial by sand of snow that has fallen on the dune surface or the synchronous transportation and deposition of snow, sand and ice. Both of these mechanisms have been reported for polar dunes on Earth. Niveo-aeolian deposits in polar deserts on Earth have unique morphologies and sedimentary structures that are generally not found in warm desert dunes. Recent analysis of MOC-scale data have found evidence for potential niveo-aeolian and denivation deposits in sand dunes on Mars.

  19. Recent Aeolian Dune Change on Mars

    NASA Technical Reports Server (NTRS)

    Bourke, M. C.; Edgett, K. S.; Cantor, B. A.

    2007-01-01

    Previous comparisons of Martian aeolian dunes in satellite images have not detected any change in dune form or position. Here, we show dome dunes in the north polar region that shrank and then disappeared over a period of 3.04 Mars years (5.7 Earth years), while larger, neighboring dunes showed no erosion or movement. The removal of sand from these dunes indicates that not only is the threshold wind speed for saltation exceeded under present conditions on Mars, but that any sand that is available for transport is likely to be moved. Dunes that show no evidence of change could be crusted, indurated. or subject to infrequent episodes of movement.

  20. Iron(II) supramolecular helicates interfere with the HIV-1 Tat–TAR RNA interaction critical for viral replication

    PubMed Central

    Malina, Jaroslav; Hannon, Michael J.; Brabec, Viktor

    2016-01-01

    The interaction between the HIV-1 transactivator protein Tat and TAR (transactivation responsive region) RNA, plays a critical role in HIV-1 transcription. Iron(II) supramolecular helicates were evaluated for their in vitro activity to inhibit Tat–TAR RNA interaction using UV melting studies, electrophoretic mobility shift assay, and RNase A footprinting. The results demonstrate that iron(II) supramolecular helicates inhibit Tat-TAR interaction at nanomolar concentrations by binding to TAR RNA. These studies provide a new insight into the biological potential of metallosupramolecular helicates. PMID:27405089

  1. Iron(II) supramolecular helicates interfere with the HIV-1 Tat-TAR RNA interaction critical for viral replication.

    PubMed

    Malina, Jaroslav; Hannon, Michael J; Brabec, Viktor

    2016-07-12

    The interaction between the HIV-1 transactivator protein Tat and TAR (transactivation responsive region) RNA, plays a critical role in HIV-1 transcription. Iron(II) supramolecular helicates were evaluated for their in vitro activity to inhibit Tat-TAR RNA interaction using UV melting studies, electrophoretic mobility shift assay, and RNase A footprinting. The results demonstrate that iron(II) supramolecular helicates inhibit Tat-TAR interaction at nanomolar concentrations by binding to TAR RNA. These studies provide a new insight into the biological potential of metallosupramolecular helicates.

  2. Inland aeolian deposits of the Iberian Peninsula: Sand dunes and clay dunes of the Duero Basin and the Manchega Plain. Palaeoclimatic considerations

    NASA Astrophysics Data System (ADS)

    Bernat Rebollal, M.; Pérez-González, A.

    2008-12-01

    This paper describes the latest research on the geomorphological characteristics, formation environment and chronology of the main inland aeolian deposits from the south-eastern Duero Basin (DB) and the Manchega Plain (MP) of the Iberian Peninsula. Similarities and differences between the aeolian deposits of these two locations are summarised. Wind deflation from the Guadiana and Júcar alluvial systems created the aeolian deposits of the MP. These deposits are mainly composed of quartz sands. However, in the San Juan alluvial plain (MP) there is a large extent of clay dunes formed by exposure to prevalent winds of seasonal playa-lakes with salt and clay sediments. In the DB, wind remobilisation of the small particles from Quaternary terraces and Tertiary arkosic sediments left aeolian deposits of quartz-feldspar sands. Textural parameters of the aeolian deposits show large variations depending on the location and the original deposit. Thus, in the DB the aeolian sands derived from the deflation of fluvial sediments are better sorted and smaller in grain size than those created by the deflation of arkosic sediments. Morphologically, simple and compound parabolic dunes (U-V forms, hemicyclic, lobate and elongate), crescentic and linear dunes, climbing dunes and blowout dunes have been recognized at both sites. Barchan and dome dunes are present only in the DB while "lunette lunette-clay dunes" are found only in the MP. In both locations, the large extent of aeolian sand sheets and the predominance of simple and compound parabolic dunes indicates the active role of sparse vegetation cover in the formation of this aeolian system. In the DB, dunes were formed by southwest and west winds, while in the MP the aeolian morphologies indicate that the prevalent winds were west and northwest. The chronology of the dune deposits is being determined with luminescence (TL-OSL) dating and Mass Spectrometry Analysis ( 14C-AMS). In this way, the aeolian activity and stabilisation

  3. Ridge: a computer program for calculating ridge regression estimates

    Treesearch

    Donald E. Hilt; Donald W. Seegrist

    1977-01-01

    Least-squares coefficients for multiple-regression models may be unstable when the independent variables are highly correlated. Ridge regression is a biased estimation procedure that produces stable estimates of the coefficients. Ridge regression is discussed, and a computer program for calculating the ridge coefficients is presented.

  4. Crystallization and preliminary X-ray diffraction analysis of the periplasmic domain of the Escherichia coli aspartate receptor Tar and its complex with aspartate

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

    Mise, Takeshi; Matsunami, Hideyuki; Samatey, Fadel A.

    The periplasmic domain of the E. coli aspartate receptor Tar was cloned, expressed, purified and crystallized with and without bound ligand. The crystals obtained diffracted to resolutions of 1.58 and 1.95 Å, respectively. The cell-surface receptor Tar mediates bacterial chemotaxis toward an attractant, aspartate (Asp), and away from a repellent, Ni{sup 2+}. To understand the molecular mechanisms underlying the induction of Tar activity by its ligands, the Escherichia coli Tar periplasmic domain with and without bound aspartate (Asp-Tar and apo-Tar, respectively) were each crystallized in two different forms. Using ammonium sulfate as a precipitant, crystals of apo-Tar1 and Asp-Tar1 weremore » grown and diffracted to resolutions of 2.10 and 2.40 Å, respectively. Alternatively, using sodium chloride as a precipitant, crystals of apo-Tar2 and Asp-Tar2 were grown and diffracted to resolutions of 1.95 and 1.58 Å, respectively. Crystals of apo-Tar1 and Asp-Tar1 adopted space group P4{sub 1}2{sub 1}2, while those of apo-Tar2 and Asp-Tar2 adopted space groups P2{sub 1}2{sub 1}2{sub 1} and C2, respectively.« less

  5. A review of the chronologies and geomorphology of the aeolian landforms in the northwestern Negev dunefield (Israel)

    NASA Astrophysics Data System (ADS)

    Roskin, Joel

    2015-04-01

    The northwestern (NW) Negev Desert dunefield covering an area of only 1,300 km2, comprises the eastern end of the northern Sinai Peninsula - NW Negev erg and is probably the most densely dated dune body in the INQUA Dunes Atlas chronologic database. Over 230 luminescence ages (TL, IRSL, and mainly OSL) and radiocarbon dates have been retrieved over the past course of 20 years from calcic and sandy palaeosols serving as dune substrates, sand sheets, vegetated linear dunes (VLDs), fluvial deposits, and archaeological sites. Despite being from different deposit types and aeolian morphologies, and based on different methodologies, the chronologies usually show good compatibility. By reviewing and reassessing the significance of the Eastern Mediterranean INQUA Dunes Atlas chronologies, along with detailed stratigraphic, structural and geomorphologic data and understandings, the major, and possibly extreme, episodes of aeolian activity and stability are outlined. Repetitive chronostratigraphic sequences in VLDs indicate that this dune type, at least in the Negev, comprises a reliable recorder of main dune mobilization periods. This presentation demonstrates that certain combinations of research finds, using different OSL dating strategies and other regional and local late Quaternary records and in particular aeolian ones, are required assets for providing for acceptable local and regional palaeoclimatic interpretations. The distribution of the VLD chronologies points to rapid mobilization during the Heinrich 1 and Younger Dryas, characterized by powerful winds, though VLDs also form in late Holocene palaeoenvironments. Time slices illustrate the different sensitivities of the studied aeolian landforms to the source, availability, and supply of sediment; long- and short-term climate change, local human-induced environmental changes and also their joint effects, that enable evaluation of aeolian responses to future environmental and climate changes.

  6. Potential contributions of asphalt and coal tar to black carbon quantification in urban dust, soils, and sediments

    USGS Publications Warehouse

    Yang, Y.; Mahler, B.J.; Van Metre, P.C.; Ligouis, B.; Werth, C.J.

    2010-01-01

    Measurements of black carbon (BC) using either chemical or thermal oxidation methods are generally thought to indicate the amount of char and/or soot present in a sample. In urban environments, however, asphalt and coal-tar particles worn from pavement are ubiquitous and, because of their pyrogenic origin, could contribute to measurements of BC. Here we explored the effect of the presence of asphalt and coal-tar particles on the quantification of BC in a range of urban environmental sample types, and evaluated biases in the different methods used for quantifying BC. Samples evaluated were pavement dust, residential and commercial area soils, lake sediments from a small urban watershed, and reference materials of asphalt and coal tar. Total BC was quantified using chemical treatment through acid dichromate (Cr2O7) oxidation and chemo-thermal oxidation at 375??C (CTO-375). BC species, including soot and char/charcoal, asphalt, and coal tar, were quantified with organic petrographic analysis. Comparison of results by the two oxidation methods and organic petrography indicates that both coal tar and asphalt contribute to BC quantified by Cr2O7 oxidation, and that coal tar contributes to BC quantified by CTO-375. These results are supported by treatment of asphalt and coal-tar reference samples with Cr2O7 oxidation and CTO-375. The reference asphalt is resistant to Cr2O7 oxidation but not to CTO-375, and the reference coal tar is resistant to both Cr2O7 oxidation and CTO-375. These results indicate that coal tar and/or asphalt can contribute to BC measurements in samples from urban areas using Cr2O7 oxidation or CTO-375, and caution is advised when interpreting BC measurements made with these methods. ?? 2010 Elsevier Ltd.

  7. A comparison of physicochemical methods for the remediation of porous medium systems contaminated with tar

    NASA Astrophysics Data System (ADS)

    Hauswirth, Scott C.; Miller, Cass T.

    2014-10-01

    The remediation of former manufactured gas plant (FMGP) sites contaminated with tar DNAPLs (dense non-aqueous phase liquids) presents a significant challenge. The tars are viscous mixtures of thousands of individual compounds, including known and suspected carcinogens. This work investigates the use of combinations of mobilization, solubilization, and chemical oxidation approaches to remove and degrade tars and tar components in porous medium systems. Column experiments were conducted using several flushing solutions, including an alkaline-polymer (AP) solution containing NaOH and xanthan gum (XG), a surfactant-polymer (SP) solution containing Triton X-100 surfactant (TX100) and XG, an alkaline-surfactant-polymer (ASP) solution containing NaOH, TX100, and XG, and base-activated sodium persulfate both with and without added TX100. The effectiveness of the flushing solutions was assessed based on both removal of polycyclic aromatic hydrocarbon (PAH) mass and on the reduction of dissolved-phase PAH concentrations. SP flushes of 6.6 to 20.9 PV removed over 99% of residual PAH mass and reduced dissolved-phase concentrations by up to two orders of magnitude. ASP flushing efficiently removed 95-96% of residual PAH mass within about 2 PV, and significantly reduced dissolved-phase concentrations of several low molar mass compounds, including naphthalene, acenaphthene, fluorene, and phenanthrene. AP flushing removed a large portion of the residual tar (77%), but was considerably less effective than SP and ASP in terms of the effect on dissolved PAH concentrations. Persulfate was shown to oxidize tar components, primarily those with low molar mass, however, the overall degradation was relatively low (30-50% in columns with low initial tar saturations), and the impact on dissolved-phase concentrations was minimal.

  8. Aeolian Abrasion at the Curiosity Landing Site: Clues to the Role of Wind in Landscape Modification

    NASA Astrophysics Data System (ADS)

    Bridges, N. T.; Le Mouélic, S.; Hallet, B.; Newman, C. E.; Rice, M. S.; Blaney, D. L.; Calef, F. J.; Herkenhoff, K. E.; Langevin, Y.; Lewis, K. W.; Maurice, S.; Pinet, P. C.; Wiens, R. C.; de Pablo, M.; Renno, N. O.

    2013-12-01

    The broad scale geomorphology of Gale Crater reflects diverse aeolian processes, from airfall settling that likely deposited much of the upper and some of the lower units of Mt. Sharp, to evidence of extensive wind exhumation and removal of material exterior to the mound, to active dunes on the crater floor. The integrated effect of aeolian sand transport can also be examined on a much smaller scale by the study of ventifacts, rocks that have been abraded by windborne particles. A diversity of ventifacts are found along Curiosity's traverse through the upper 'hummocky' (HY) geomorphic unit and the lower Yellowknife Bay (YKB) sedimentary rocks. The textures are analogous to abrasion features found on Earth and include cm-scale facets, keels, elongated pits, grooves, flutes, and basal sills. High-resolution images from ChemCam's Remote Micro-Imager also show mm-scale lineations. Evidence of differential erosion is common, with HY conglomerates (e.g., Hottah, Link) and the YKB Sheepbed mudstone unit containing distinct wind tails in the lee of resistant pebbles, and bedding features within Rocknest 3, the YKB Shaler sandstone unit, and other layered rocks displaying prominent ridge-groove topography. ChemCam LIBS depth profile data so far show no strong evidence for chemical differences in the elemental composition between abraded and non-abraded surfaces (as determined from qualitative assessment), as might be expected if there were rock coatings or weathering rinds undergoing active abrasion. Preliminary measurements of ventifact texture and wind tail orientations indicate sandblasting in HY and YKB from predominantly southwesterly and northerly directions, respectively. Based on meso-scale models of current winds and REMS results, SW flow is uncommon whereas N winds are frequent. Compositional and textural information from the suite of MSL instruments indicate that HY rocks are dominated by various types of basalt (either as whole rocks or the resistant clasts in

  9. Volatilization of polycyclic aromatic hydrocarbons from coal-tar-sealed pavement.

    PubMed

    Van Metre, Peter C; Majewski, Michael S; Mahler, Barbara J; Foreman, William T; Braun, Christopher L; Wilson, Jennifer T; Burbank, Teresa L

    2012-06-01

    Coal-tar-based pavement sealants, a major source of PAHs to urban water bodies, are a potential source of volatile PAHs to the atmosphere. An initial assessment of volatilization of PAHs from coal-tar-sealed pavement is presented here in which we measured summertime gas-phase PAH concentrations 0.03 m and 1.28 m above the pavement surface of seven sealed (six with coal-tar-based sealant and one with asphalt-based sealant) and three unsealed (two asphalt and one concrete) parking lots in central Texas. PAHs also were measured in parking lot dust. The geometric mean concentration of the sum of eight frequently detected PAHs (ΣPAH(8)) in the 0.03-m samples above sealed lots (1320 ng m(-3)) during the hottest part of the day was 20 times greater than that above unsealed lots (66.5 ng m(-3)). The geometric mean concentration in the 1.28-m samples above sealed lots (138 ng m(-3)) was five times greater than above unsealed lots (26.0 ng m(-3)). Estimated PAH flux from the sealed lots was 60 times greater than that from unsealed lots (geometric means of 88 and 1.4 μg m(-2) h(-1), respectively). Although the data set presented here is small, the much higher estimated fluxes from sealed pavement than from unsealed pavement indicate that coal-tar-based sealants are emitting PAHs to urban air at high rates compared to other paved surfaces. Published by Elsevier Ltd.

  10. Development of secondary chamber for tar cracking-improvement of wood pyrolysis performance in pre-vacuum chamber

    NASA Astrophysics Data System (ADS)

    Siahaan, S.; Homma, H.; Homma, H.

    2018-02-01

    Energy crisis and global warming, in other words, climate change are critical topics discussed in various parts of the world. Global warming primarily result from too much emission of carbon dioxide (CO2) in the atmosphere. To mitigate global warming, or climate change and improve electrification in rural areas, wood pyrolysis technology is developed in a laboratory scale, of which gases are directly applicable to the gas engine generator. Our laboratory has developed a prototype of wood pyrolysis plant with a pre-vacuum chamber. However, tar yield was around 40 wt% of feedstock. This research aims to reduce tar yield by secondary tar cracking. For the secondary tar cracking, a secondary pre-vacuum chamber is installed after primary pre-vacuum chamber. Gases generated in the primary pre-vacuum chamber are lead into the secondary chamber that is heated up to 1000 K. This paper reports performance of the secondary chamber for secondary tar cracking in homogeneous mode and heterogeneous mode with char.

  11. Aeolian snow transport from wind tunnel experiments

    NASA Astrophysics Data System (ADS)

    Paterna, E.; Crivelli, P.; Lehning, M.

    2016-12-01

    Aeolian snow transport has a significant impact on snow redistribution in mountains, prairies as well as on glaciers, ice shelves, and sea ice. In all these environments, the local mass balance is highly influenced by Aeolian snow transport. The dynamics of snow saltation has a high impact on the land surface processes shaping these regions. More specifically, the observed high intermittency of saltation fluxes poses a problem for saltation models and needs to be better understood. We therefore aimed at unveiling the mechanisms underlying snow saltation at different saltation strengths and its coupling with the turbulent fluctuations of the wind. We conducted wind tunnel measurements of the momentum and mass-fluxes during snow saltation. For the mass-flux measurements we employed a shadowgraphy system which acquires images of the snow particle's shadows at high spatial and temporal resolution. The size and displacement of the particles are then determined by means of image analysis and Particle Tracking Velocimetry (PTV), allowing to estimate both snow mass-flux and flow velocity. Our controlled wind tunnel experiments revealed the existence of two regimes of saltation. In a turbulence-dependent regime occurring during weak saltation activity, we observed a strong coupling between snow transport and turbulent flow. Conversely during stronger saltation activity a turbulence-independent regime emerges, where the saltation develops its own length scale and it efficiently decouples from the wind fluctuations. We argue that different entrainment mechanisms could explain the existence of the two different saltation regimes as well as the observed high level of mass-flux intermittency.

  12. Spatial and temporal variations of aeolian sediment input to the tributaries (the Ten Kongduis) of the upper Yellow River

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Shi, Changxing

    2018-02-01

    The Ten Kongduis of the upper Yellow River, located in Inner Mongolia, northern China, is an area with active wind-water coupled erosion and hence one of the main sediment sources of the Yellow River. In this study, we analyzed the characteristics of spatial and temporal variations of aeolian sediment input to the river channel. For this purpose, three segments of sand dune-covered banks of the Maobula and the Xiliugou kongduis were investigated three times from November 2014 to November 2015 using a 3-D laser scanner, and the displacement of banks of desert reaches of three kongduis was derived from interpreting remote sensing images taking in the years from 2005 to 2015. The data of the surveyed sand dunes reveal that the middle kongduis were fed by aeolian sand through the sand dunes moving towards the river channels. The amount of aeolian sediment input was estimated to be about 14.94 × 104 t/yr in the Maobula Kongdui and about 5.76 × 104 t/yr in the Xiliugou Kongdui during the period from November 2014 to November 2015. According to the interpretation results of remote sensing images, the amount of aeolian sediment input to the Maobula Kongdui was about 15.74 × 104 t in 2011 and 18.2 × 104 t in 2012. In the Xiliugou Kongdui, it was in the range of 9.52 × 104 - 9.99 × 104 t in 2012 and in the springs of 2013 and 2015. In the Hantaichuan Kongdui, it was 7.04 × 104 t in 2012, 7.53 × 104 t in the spring of 2013, and 8.52 × 104 t in the spring of 2015. Owing to the changes in wind and rainfall, both interseasonal and interannual sediment storage and release mechanisms exist in the processes of aeolian sand being delivered into the kongduis. However, all of the aeolian sediment input to the Ten Kongduis should be delivered downstream by the river flows during a long term.

  13. Turbulent Flow and Sand Dune Dynamics: Identifying Controls on Aeolian Sediment Transport

    NASA Astrophysics Data System (ADS)

    Weaver, C. M.; Wiggs, G.

    2007-12-01

    Sediment transport models are founded on cubic power relationships between the transport rate and time averaged flow parameters. These models have achieved limited success and recent aeolian and fluvial research has focused on the modelling and measurement of sediment transport by temporally varying flow conditions. Studies have recognised turbulence as a driving force in sediment transport and have highlighted the importance of coherent flow structures in sediment transport systems. However, the exact mechanisms are still unclear. Furthermore, research in the fluvial environment has identified the significance of turbulent structures for bedform morphology and spacing. However, equivalent research in the aeolian domain is absent. This paper reports the findings of research carried out to characterise the importance of turbulent flow parameters in aeolian sediment transport and determine how turbulent energy and turbulent structures change in response to dune morphology. The relative importance of mean and turbulent wind parameters on aeolian sediment flux was examined in the Skeleton Coast, Namibia. Measurements of wind velocity (using sonic anemometers) and sand transport (using grain impact sensors) at a sampling frequency of 10 Hz were made across a flat surface and along transects on a 9 m high barchan dune. Mean wind parameters and mass sand flux were measured using cup anemometers and wedge-shaped sand traps respectively. Vertical profile data from the sonic anemometers were used to compute turbulence and turbulent stress (Reynolds stress; instantaneous horizontal and vertical fluctuations; coherent flow structures) and their relationship with respect to sand transport and evolving dune morphology. On the flat surface time-averaged parameters generally fail to characterise sand transport dynamics, particularly as the averaging interval is reduced. However, horizontal wind speed correlates well with sand transport even with short averaging times. Quadrant

  14. Optical, Physical and Chemical Properties of Tar Balls Observed During the Yosemite Aerosol Characterization Study

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

    Hand, Jenny L.; Malm, W. C.; Laskin, Alexander

    2005-11-09

    The Yosemite Aerosol Characterization Study of summer 2002 (YACS) occurred during an active fire season in the western U. S., and provided an opportunity to investigate many unresolved issues related to the radiative effects of biomass burning aerosols. Single particle analysis was performed on field collected aerosol samples using an array of electron microscopy techniques. Amorphous carbon spheres, or “tar balls”, were present in samples collected during episodes of high particle light scattering coefficients that occurred during the peak of a smoke/haze event. The highest concentrations of light-absorbing carbon from a dual-wavelength aethalometer (λ = 370 and 880 nm) occurredmore » during periods when the particles were predominantly tar balls, indicating they do absorb light in the UV and near-IR range of the solar spectrum. Closure experiments of mass concentrations and light scattering coefficients during periods dominated by tar balls did not require any distinct assumptions of organic carbon molecular weight correction factors, density, or refractive index compared to periods dominated by other types of organic carbon aerosols. Measurements of the hygroscopic behavior of tar balls using an environmental SEM indicate that tar balls do not exhibit deliquescence, but do uptake some water at high (~83 %) relative humidity. The ability of tar balls to efficiently scatter and absorb light, and to absorb water has important implications for their role in regional haze and climate fence.« less

  15. The contribution of micrometeorites to the iron stocks of buried podzols, developed in Late-glacial aeolian sand deposits (Brabant, The Netherlands)

    NASA Astrophysics Data System (ADS)

    van Mourik, Jan; de Vet, Sebastiaan

    2015-04-01

    The surface geology of an extensive part of NW-Europe is dominated by coversands (Late-glacial chemical poor aeolian sand deposits). The geomorphology of coversand landscapes is dominated by ridges and planes. Podzolation is the dominant soil forming process in coversands under moderate humid climatic conditions. Umbric Podzols developed on the ridges under Quercetum-mixtum, Gleyic and Histic Podzols developed in the planes under Alnetum. Even in chemical poor coversands, iron will be released by hydrolysis from iron containing silicate minerals (such as feldspars). It is well known that the vertical iron distribution in Podzols is effected by translocation of active iron from eluvial to illuvial horizons and that iron is leaching to the aquifer. Iron stocks of Podzols, in contrasts, have not been widely studied for comparison purposes of individual soil horizons or between soils. We determined the stocks of active and immobile iron in the horizons of buried xeromorphic Podzols (soils that developed without any contact with groundwater). The results show that the total amount of iron exceeds the potential amount which can be released by hydrolysis from the parent material. Furthermore, to amount of iron that leached to the groundwater is unknown. It is evident that we must find an additional source to explain the total iron stocks in buried Podzols. It is known from analysis of ice cores that the earth atmosphere is subjected to a continuous influx of (iron rich) micrometeorites. The precipitation of micrometeorites (and other aerosols) on the earth surface is concentrated in humid climatic zones with (intensive) rain fall. We analyzed minerals, extracted from the ectorganic horizon of the Initial Podzols, developed in driftsand that stabilized around 1900 AD, overlying Palaeopodzols, buried around 1200 AD. Among blown in quartz grains, we could determine also micrometeorites, embedded in the organic skeleton of the fermentation horizon of the Initial Podzol

  16. Comparative evaluation of topical calcipotriol versus coal tar and salicylic acid ointment in chronic plaque psoriasis.

    PubMed

    Singh, Preeti; Gupta, Surabhi; Abidi, Afroz; Krishna, Arvind

    2013-08-01

    Calcipotriol is a newer topical treatment option available for plaque psoriasis and coal tar being one of the oldest treatment and still in use. To evaluate and compare the differences in terms of efficacy, safety and relapse with Calcipotriol 0.005% (50 mcg/gm) and 6% coal tar and 3% salicylic ointment in patients with Plaque psoriasis. SETTING and Study conducted on 60 patients of plaque psoriasis, who attended the skin OPD in our hospital. The patients with mild to moderate plaque psoriasis were selected. 60 patients were enrolled for the study after obtaining informed consent. Subjects were asked to apply Calcipotriol 0.005% (50 mcg/gm) (Heximar Win care) twice a day on the right side plaques and on left side plaques, Petroleum jelly (Vaseline) in the morning and 6% coal tar and 3% salicylic ointment (Protar® Percos) at nighttime. PASI score was used to assess the reponse to therapy at 2nd, 4th, 6th and 8th week. After treatment subjects were observed for 6 weeks for any relapse. It was done by paired t-test and independent sample t-test. The results showed that statistically significant difference was seen in the mean percentage reduction of PASI score between both the groups, at all the assessment visits, 2, 4, 6, and 8 weeks, the mean percentage reduction at 2 weeks for calcipotriol being 21±12.06 and for coal tar being 13.44±11.19 (P=0.000), at 4 weeks for calcipotriol was 40±16.71 and for coal tar 25±99 (P=0.000), at 6 weeks for calcipotriol was 53.99+-22.43 and for coal tar 41±21.23 (P=0.002), at 8 weeks for calcipotriol was 62.73±24.04 and for coal tar was 51.53±23.27 (P=0.11). Relapse was seen in 5/60 (8.3%) of patients on calcipotriol treated side and 9/60 (15%) of patients with coal tar treated side. Thus it can be concluded that calcipotriol cream is more efficacious when compared with coal tar and does have a quick response. It is well tolerated and acceptable cosmetically.

  17. Selected constituents in the smokes of U. S. commercial cigaretts: tar, nicotine, carbon monoxide and carbon dioxide

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

    Jenkins, R.A.; Quincy, R.B.; Guerin, M.R.

    One hundred twenty-one brands of United States commercial cigarettes were analyzed for their deliveries of tar, nicotine, carbon monoxide, and carbon dioxide under standard analytical smoking conditions. The sample included both filter and nonfilter cigarettes. Comparisons of carbon monoxide deliveries over the range of observed tar deliveries indicated a very high correlation between CO and tar for filter cigarettes, but nonfilter cigarettes tended to produce much less CO than would have been predicted from their tar deliveries. Comparison of ORNL nicotine values for specific brands with those determined by the Federal Trade Commission yield no statistically significant differences between laboratories.more » 4 figures, 6 tables.« less

  18. Atmospheric stability and diurnal patterns of aeolian saltation on the Llano Estacado

    USDA-ARS?s Scientific Manuscript database

    Aeolian transport is driven by aerodynamic surface stress imposed by turbulent winds in the Earth’s atmospheric boundary layer (ABL). ABL regime is influenced by stratification, which can either enhance or suppress production of turbulence by shear associated with the vertical gradient of streamwise...

  19. Ligand-induced changes in 2-aminopurine fluorescence as a probe for small molecule binding to HIV-1 TAR RNA

    PubMed Central

    BRADRICK, THOMAS D.; MARINO, JOHN P.

    2004-01-01

    Replication of human immunodeficiency virus type 1 (HIV-1) is regulated in part through an interaction between the virally encoded trans-activator protein Tat and the trans-activator responsive region (TAR) of the viral RNA genome. Because TAR is highly conserved and its interaction with Tat is required for efficient viral replication, it has received much attention as an antiviral drug target. Here, we report a 2-aminopurine (2-AP) fluorescence-based assay for evaluating potential TAR inhibitors. Through selective incorporation of 2-AP within the bulge (C23 or U24) of a truncated form of the TAR sequence (Δ TAR-ap23 and Δ TAR-ap24), binding of argininamide, a 24-residue arginine-rich peptide derived from Tat, and Neomycin has been characterized using steady-state fluorescence. Binding of argininamide to the 2-AP ΔTAR constructs results in a four- to 11-fold increase in fluorescence intensity, thus providing a sensitive reporter of that interaction (KD ~ 1 mM). Similarly, binding of the Tat peptide results in an initial 14-fold increase in fluorescence (KD ~ 25 nM), but is then followed by a slight decrease that is attributed to an additional, lower-affinity association(s). Using the ΔTAR-ap23 and TAR-ap24 constructs, two classes of Neomycin binding sites are detected; the first molecule of antibiotic binds as a noncompetitive inhibitor of Tat/argininamide (KD ~ 200 nM), whereas the second, more weakly bound molecule(s) becomes associated in a presumably nonspecific manner (KD ~ 4 μM). Taken together, the results demonstrate that the 2-AP fluorescence-detected binding assays provide accurate and general methods for quantitatively assessing TAR interactions. PMID:15273324

  20. Pyrolysis of aseptic packages (tetrapak) in a laboratory screw type reactor and secondary thermal/catalytic tar decomposition.

    PubMed

    Haydary, J; Susa, D; Dudáš, J

    2013-05-01

    Pyrolysis of aseptic packages (tetrapak cartons) in a laboratory apparatus using a flow screw type reactor and a secondary catalytic reactor for tar cracking was studied. The pyrolysis experiments were realized at temperatures ranging from 650 °C to 850 °C aimed at maximizing of the amount of the gas product and reducing its tar content. Distribution of tetrapak into the product yields at different conditions was obtained. The presence of H2, CO, CH4, CO2 and light hydrocarbons, HCx, in the gas product was observed. The Aluminum foil was easily separated from the solid product. The rest part of char was characterized by proximate and elemental analysis and calorimetric measurements. The total organic carbon in the tar product was estimated by elemental analysis of tars. Two types of catalysts (dolomite and red clay marked AFRC) were used for catalytic thermal tar decomposition. Three series of experiments (without catalyst in a secondary cracking reactor, with dolomite and with AFRC) at temperatures of 650, 700, 750, 800 and 850 °C were carried out. Both types of catalysts have significantly affected the content of tars and other components in pyrolytic gases. The effect of catalyst on the tetrapack distribution into the product yield on the composition of gas and on the total organic carbon in the tar product is presented in this work. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. A study of the management strategies for river aeolian dust inhibition at the estuary of Zhuo-shui River

    NASA Astrophysics Data System (ADS)

    Tsai, S. F.; Lin, C. Y.

    2014-12-01

    With the characteristics of humidity in summer and drought in winter, there existing lots of bare lands due to the decline of water level cause large amounts of aeolian dust and environmental deterioration during the monsoon seasons in central Taiwan. How to adopt effective measures to inhibit the damage of dust is an essential issue. This study selected the serious dust-affected section of Zhuo-shui river (bridge Zi-qiang to Xi-bin) to delineate the areas of potential aeolian dust occurrence, explore the relationship between elevation and water level determined from return period analysis, submit the countermeasures for dust inhibition at the bare lands and/or cultivated areas, and address the responsibilities of related authority offices for dust prevention by means of literature review. The return period of inundation for the areas of potential aeolian dust occurrence is 1.1 years. Engineering of dust prevention with highly unit price are not recommended due to could be destroyed annually. The deposition sites of a river are usually located at the convex bank, which with silt texture and high salinity are not suitable for cultivation, are delineated as the areas of potential aeolian dust occurrence. Besides technology consideration in dust prevention, this study also examined the related articles of river management to integrate a comprehensive vision for better riverside environment and air quality.

  2. Aeolian processes during the Holocene in Gannan Region, Eastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Yang, S.; Cheng, T.; Li, S.; Liang, M.

    2016-12-01

    Aeolian desertification occurring in the Tibetan Plateau has received attention recently for it has become a severe environmental problem by accelerating the grassland degradation and eco-environment damage. The Gannan Region is located in the northeastern Tibetan Plateau with a mean altitude of 3500m. It is highly sensitive to global environmental change and human disturbance. Serious soil erosion and desertification and extensive land degradation have caused heavy eco-environmental impacts. To investigate the evolution of the desertification in Holocene in the Plateau is of great importance for understanding the desertification trend under the global changes in the Tibetan Plateau. Loess and aeolian sands is a key geological archive related to desertification processes and the past environment changes. In this study a typical 8.5m-thick loess-sands profile named MQQ, was selected at the Maqu city. It is situated on the first terrace (T1) of the Yellow River. Detailed accelerator mass spectrometry (AMS) 14C dating of bulk organic matter content has shown the Aeolian sediments of the MQQ section occurring since the early Holocene. the mass-specific frequency-dependent magnetic susceptibility (χfd) and grainsize records show a clear upward increase in the contents of superparamagnetic grains and fine fractions in grain size, which indicates a gradual wetting trend during the Holocene.The sediment rates change from very high in the early Holocene to low values after 8.2 ka. The wetting process can be divided into three steps: 10.0-8.2 ka, 8.2-3.0 ka and 3.0-present. It indicates that the climate in the eastern Tibetan Plateau was dry during the early Holocene. After that the climate was getting wet gradually. The variations of the westerlies and the Asian monsoon may cause the environmental change in this region.

  3. Identification of amino acids that promote specific and rigid TAR RNA-tat protein complex formation.

    PubMed

    Edwards, Thomas E; Robinson, Bruce H; Sigurdsson, Snorri Th

    2005-03-01

    The Tat protein and the transactivation responsive (TAR) RNA form an essential complex in the HIV lifecycle, and mutations in the basic region of the Tat protein alter this RNA-protein molecular recognition. Here, EPR spectroscopy was used to identify amino acids, flanking an essential arginine of the Tat protein, which contribute to specific and rigid TAR-Tat complex formation by monitoring changes in the mobility of nitroxide spin-labeled TAR RNA nucleotides upon binding. Arginine to lysine N-terminal mutations did not affect TAR RNA interfacial dynamics. In contrast, C-terminal point mutations, R56 in particular, affected the mobility of nucleotides U23 and U38, which are involved in a base-triple interaction in the complex. This report highlights the role of dynamics in specific molecular complex formation and demonstrates the ability of EPR spectroscopy to study interfacial dynamics of macromolecular complexes.

  4. Geomorphology and drift potential of major aeolian sand deposits in Egypt

    NASA Astrophysics Data System (ADS)

    Hereher, Mohamed E.

    2018-03-01

    Aeolian sand deposits cover a significant area of the Egyptian deserts. They are mostly found in the Western Desert and Northern Sinai. In order to understand the distribution, pattern and forms of sand dunes in these dune fields it is crucial to analyze the wind regimes throughout the sandy deserts of the country. Therefore, a set of wind data acquired from twelve meteorological stations were processed in order to determine the drift potential (DP), the resultant drift potential (RDP) and the resultant drift direction (RDD) of sand in each dune field. The study showed that the significant aeolian sand deposits occur in low-energy wind environments with the dominance of linear and transverse dunes. Regions of high-energy wind environments occur in the south of the country and exhibit evidence of deflation rather than accumulation with the occurrence of migratory crescentic dunes. Analysis of the sand drift potentials and their directions help us to interpret the formation of major sand seas in Egypt. The pattern of sand drift potential/direction suggests that the sands in these seas might be inherited from exogenous sources.

  5. Threshold wind velocity dynamics as a driver of aeolian sediment mas flux

    USDA-ARS?s Scientific Manuscript database

    Horizontal (saltation) mass flux is a key driver of aeolian dust emission. Estimates of the horizontal mass flux underpin assessments of the global dust budget and influence our understanding of the dust cycle and its interactions. Current equations for predicting horizontal mass flux are based on l...

  6. Machine-smoking studies of cigarette filter color to estimate tar yield by visual assessment and through the use of a colorimeter.

    PubMed

    Morton, Michael J; Williams, David L; Hjorth, Heather B; Smith, Jennifer H

    2010-04-01

    This paper explores using the intensity of the stain on the end of the filter ("filter color") as a vehicle for estimating cigarette tar yield, both by instrument reading of the filter color and by visual comparison to a template. The correlation of machine-measured tar yield to filter color measured with a colorimeter was reasonably strong and was relatively unaffected by different puff volumes or different tobacco moistures. However, the correlation of filter color to machine-measured nicotine yield was affected by the moisture content of the cigarette. Filter color, as measured by a colorimeter, was generally comparable to filter extraction of either nicotine or solanesol in its correlation to machine-smoked tar yields. It was found that the color of the tar stain changes over time. Panelists could generally correctly order the filters from machine-smoked cigarettes by tar yield using the intensity of the tar stain. However, there was considerable variation in the panelist-to-panelist tar yield estimates. The wide person-to-person variation in tar yield estimates, and other factors discussed in the text could severely limit the usefulness and practicality of this approach for visually estimating the tar yield of machine-smoked cigarettes. Copyright 2009 Elsevier Inc. All rights reserved.

  7. Ridge Tectonics, Magma Supply, and Ridge-Hotpot Interaction at the Eastern End of the Australian-Antarctic Ridge

    NASA Astrophysics Data System (ADS)

    Kim, S.; Lin, J.; Park, S.; Choi, H.; Lee, S.

    2013-12-01

    During 2011-2013 the Korea Polar Research Institute (KOPRI) conducted three successive expeditions to the eastern end of the Australian-Antarctic Ridge (AAR) to investigate the tectonics, geochemistry, and hydrothermal activity of this intermediate fast spreading system. On board the Korean icebreaker R/V Araon, the science party collected multiple types of data including multibeam bathymetry, gravity, magnetics, as well as rock and water column samples. In addition, Miniature Autonomous Plume Recorders (MAPRs) were deployed at each of the wax-core rock sampling sites to detect the presence of active hydrothermal vents. In this study, we present a detailed analysis of a 360-km-long super-segment at the eastern end of the AAR to quantify the spatial variations in ridge morphology and investigate its respond to changes in melt supply. The study region contains several intriguing bathymetric features including (1) abrupt changes in the axial topography, alternating between rift valleys and axial highs within relatively short ridge segments; (2) overshooting ridge tips at the ridge-transform intersections; (3) systematic migration patterns of hooked ridges; (4) a 350-km-long mega-transform fault; and (5) robust axial and off-axis volcanisms. To obtain a proxy for regional variations in magma supply, we calculated residual mantle Bouguer gravity anomalies (RMBA), gravity-derived crustal thickness, and residual topography for seven sub-segments. The results of the analyses revealed that the southern flank of the AAR is associated with a shallower seafloor, more negative RMBA, thicker crust, and/or less dense mantle than the conjugate northern flank. Furthermore, this N-S asymmetry becomes more prominent toward the super-segment of the AAR. Such regional variations in seafloor topography and RMBA are consistent with the hypothesis that ridge segments in the study area have interacted with the Balleny hotspot, currently lies southwest of the AAR. However, the influence of

  8. Abrasion by aeolian particles: Earth and Mars

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Marshall, J. R.; White, B. R.; Pollack, J. B.; Marshall, J.; Krinsley, D.

    1984-01-01

    Estimation of the rate of aeolian abrasion of rocks on Mars requires knowledge of: (1) particle flux, (2) susceptibilities to abrasion of various rocks, and (3) wind frequencies on Mars. Fluxes and susceptibilities for a wide range of conditions were obtained in the laboratory and combined with wind data from the Viking meteorology experiment. Assuming an abundant supply of sand-sized particles, estimated rates range up to 2.1 x 10 to the minus 2 power cm of abrasion per year in the vicinity of Viking Lander 1. This rate is orders of magnitude too great to be in agreement with the inferred age of the surface based on models of impact crater flux. The discrepancy in the estimated rate of abrasion and the presumed old age of the surface cannot be explained easily by changes in climate or exhumation of ancient surfaces. The primary reason is thought to be related to the agents of abrasion. At least some sand-sized (approx. 100 micrometers) grains appear to be present, as inferred from both lander and orbiter observations. High rates of abrasion occur for all experimental cases involving sands of quartz, basalt, or ash. However, previous studies have shown that sand is quickly comminuted to silt- and clay-sized grains in the martian aeolian regime. Experiments also show that these fine grains are electrostatically charged and bond together as sand-sized aggregates. Laboratory simulations of wind abrasion involving aggregates show that at impact velocities capable of destroying sand, aggregates from a protective veneer on the target surface and can give rise to extremely low abrasion rates.

  9. A case-control study of asphalt and tar exposure and lung cancer in minorities.

    PubMed

    McClean, Michael D; Kelsey, Karl T; Sison, Jennette D; Quesenberry, Charles P; Wrensch, Margaret R; Wiencke, John K

    2011-11-01

    Considerable controversy surrounds the carcinogenic potential of asphalt and tar. Since minority individuals may have had relatively high historical exposures, we investigated asphalt and tar exposure and lung cancer risk among African Americans and Latino Americans. We conducted a case-control study of lung cancer among African Americans and Latino Americans in the San Francisco Bay area (422 cases, 894 controls). A questionnaire was used to obtain detailed work histories and exposure information. Self-reported exposure to asphalt and tar as well as other factors (e.g., smoking, automobile exhaust, and asbestos) were evaluated as predictors of lung cancer risk. Potential effect modification by cytochrome P450 (CYP) 1A1 was also explored. Self-reported duration of exposure to asphalt and tar was associated with a statistically significant excess risk of lung cancer in the overall population (OR: 1.11, 95% CI: 1.01-1.22), evaluating risk per year of exposure. Years of exposure to automobile exhaust (OR: 1.02, 95% CI: 1.00-1.05) and asbestos (OR: 1.04, 95% CI: 1.02-1.06) were also associated with statistically significant elevations in risk. In Latino Americans, the lung cancer risks associated with polycyclic aromatic hydrocarbon-related exposures were consistently higher in the CYP1A1 wild-type subjects as compared to the variant genotype subjects, and the interaction was statistically significant for smoking and the CYP1A1 M2 polymorphism (P-value(interaction) = 0.02). These data are consistent with the literature suggesting that exposure to asphalt and tar may increase risk of lung cancer. However, it was not possible to separate the effects and asphalt and tar in this study. Copyright © 2011 Wiley Periodicals, Inc.

  10. A Case-Control Study of Asphalt and Tar Exposure and Lung Cancer in Minorities

    PubMed Central

    McClean, Michael D.; Kelsey, Karl T.; Sison, Jennette D; Quesenberry, Charles P; Wrensch, Margaret R; Wiencke, John K.

    2011-01-01

    Objectives Considerable controversy surrounds the carcinogenic potential of asphalt and tar. Since minority individuals may have had relatively high historical exposures, we investigated asphalt and tar exposure and lung cancer risk among African Americans and Latino Americans. Methods We conducted a case-control study of lung cancer among African Americans and Latino Americans in the San Francisco Bay area (422 cases, 894 controls). A questionnaire was used to obtain detailed work histories and exposure information. Self-reported exposure to asphalt and tar as well as other factors (eg. smoking, automobile exhaust, and asbestos) were evaluated as predictors of lung cancer risk. Potential effect modification by cytochrome P450 (CYP) 1A1 was also explored. Results Self-reported duration of exposure to asphalt and tar was associated with a statistically significant excess risk of lung cancer in the overall population (OR: 1.11, 95%CI: 1.01–1.22), evaluating risk per year of exposure. Years of exposure to automobile exhaust (OR: 1.02, 95%CI: 1.00–1.05) and asbestos (OR: 1.04, 95%CI: 1.02–1.06) were also associated with statistically significant elevations in risk. In Latino Americans, the lung cancer risks associated with polycyclic aromatic hydrocarbon-related exposures were consistently higher in the CYP1A1 wildtype subjects as compared to the variant genotype subjects, and the interaction was statistically significant for smoking and the CYP1A1 M2 polymorphism (p-valueinteraction=0.02). Conclusions These data are consistent with the literature suggesting that exposure to asphalt and tar may increase risk of lung cancer. However, it was not possible to separate the effects and asphalt and tar in this study. PMID:21882217

  11. Aeolian Research: Reflections on progress after five years

    NASA Astrophysics Data System (ADS)

    Chappell, Adrian; Lee, Jeffrey A.

    2015-03-01

    Aeolian Research was launched in 2009 by the co-Editors in Chief, Ted Zobeck and Jeff Lee and since then more than 200 papers have been published under their guidance. The journal's first Thompson Scientific Impact Factor (IF), in 2011, was 2.179 and the IF has increased to 2.841 in 2013, which is comparable to its well-established peer journals. These achievements have been accomplished with the exceptional support of the associate editors and the broader research community in reviewing more than 400 papers. Of the papers received, more than half are published.

  12. The linear relationship between cigarette tar and nicotine yields: regulatory implications for smoke constituent ratios.

    PubMed

    St Charles, F K; Cook, C J; Clayton, P M

    2011-02-01

    Cigarette smoke analyte yields are often expressed as ratios relative to tar or nicotine yields, usually to compare different products or to estimate human uptake of smoke in relation to nicotine uptake measurements. The method, however, can lead to distorted interpretations, especially in the case of ratios from ultra-low tar yield cigarettes. In brief, as tar yields decrease below the 5–6 mg per cigarette range, the tar-to-nicotine ratio (TNR) decreases rapidly in a non-linear fashion. If, however, the nicotine yield, rather than the ratio, is plotted versus the tar yield, the non-linearity disappears and a straight line is obtained, with a slight positive intercept for nicotine on the ordinate. Unlike the ratio, the slope appears to depend only on the concentration of the nicotine in the blend and does not appear to vary with smoking parameters such as puff volume, puff interval or length smoked or with cigarette design parameters such as length, circumference or the amount of filtration or filter ventilation. Therefore, such a slope is analogous to the TNR although, unlike that ratio, it is invariant. Even more simply, the concentration of the nicotine in the blend, at least for American blend-style cigarettes, provides a similar index.

  13. Design-Based Peptidomimetic Ligand Discovery to Target HIV TAR RNA Using Comparative Analysis of Different Docking Methods.

    PubMed

    Fu, Junjie; Xia, Amy; Dai, Yao; Qi, Xin

    2016-01-01

    Discovering molecules capable of binding to HIV trans-activation responsive region (TAR) RNA thereby disrupting its interaction with Tat protein is an attractive strategy for developing novel antiviral drugs. Computational docking is considered as a useful tool for predicting binding affinity and conducting virtual screening. Although great progress in predicting protein-ligand interactions has been achieved in the past few decades, modeling RNA-ligand interactions is still largely unexplored due to the highly flexible nature of RNA. In this work, we performed molecular docking study with HIV TAR RNA using previously identified cyclic peptide L22 and its analogues with varying affinities toward HIV-1 TAR RNA. Furthermore, sarcosine scan was conducted to generate derivatives of CGP64222, a peptide-peptoid hybrid with inhibitory activity on Tat/TAR RNA interaction. Each compound was docked using CDOCKER, Surflex-Dock and FlexiDock to compare the effectiveness of each method. It was found that FlexiDock energy values correlated well with the experimental Kd values and could be used to predict the affinity of the ligands toward HIV-1 TAR RNA with a superior accuracy. Our results based on comparative analysis of different docking methods in RNA-ligand modeling will facilitate the structure-based discovery of HIV TAR RNA ligands for antiviral therapy.

  14. Facies architecture and high resolution sequence stratigraphy of an aeolian, fluvial and shallow marine system in the Pennsylvanian Piauí Formation, Parnaíba Basin, Brazil

    NASA Astrophysics Data System (ADS)

    Vieira, Lucas Valadares; Scherer, Claiton Marlon dos Santos

    2017-07-01

    The Pennsylvanian Piauí Formation records the deposition of aeolian, fluvial and shallow marine systems accumulated in the cratonic sag Parnaíba basin. Characterization of the facies associations and sequence stratigraphic framework was done by detailed description and logging of outcrops. Six facies associations were recognized: aeolian dunes and interdunes, aeolian sandsheets, fluvial channels, tidally-influenced fluvial channels, shoreface and shoreface-shelf transition. Through correlation of stratigraphic surfaces, the facies associations were organized in system tracts, which formed eight high frequency depositional sequences, bounded by subaerial unconformities. These sequences are composed of a lowstand system tract (LST), that is aeolian-dominated or fluvial-dominated, a transgressive system tract (TST) that is formed by tidally-influenced fluvial channels and/or shoreface and shoreface-shelf transition deposits with retrogradational stacking, and a highstand system tract (HST), which is formed by shoreface-shelf transition and shoreface deposits with progradational stacking. Two low frequency cycles were determined by observing the stacking of the high frequency cycles. The Lower Sequence is characterized by aeolian deposits of the LST and an aggradational base followed by a progressive transgression, defining a general TST. The Upper Sequence is characterized by fluvial deposits and interfluve pedogenesis concurring with the aeolian deposits of the LST and records a subtle regression followed by transgression. The main control on sedimentation in the Piauí Formation was glacioeustasy, which was responsible for the changes in relative sea level. Even though, climate changes were associated with glacioeustatic phases and influenced the aeolian and fluvial deposition.

  15. Implications of (reworked) aeolian sediments and paleosols for Holocene environmental change in Western Mongolia

    NASA Astrophysics Data System (ADS)

    Klinge, Michael; Lehmkuhl, Frank; Schulte, Philipp; Hülle, Daniela; Nottebaum, Veit

    2017-09-01

    In the semi-arid to semi-humid regions of western Mongolia four different geomorphological aeolian and fluvial archives were investigated in order to gain environmental information of landscape evolution during the late glacial and the Holocene. These archives, which contain aeolian deposits, fluvial sediments, and paleosols, are situated upon glacial moraines, fluvial terraces, floodplains, or mountain slopes. While radiometric dating provides information about the age of the sediment and paleosols, grain size and element distribution provide information about the sediment source and soil development. Extensive aeolian sediment transport occurred from 17 to 10 ka during the late glacial when climate was cold and dry. Since that period the developing steppe and alpine meadow vegetation served as a dust trap. During the warm and wet early to mid-Holocene sediment transport was reduced under a dense vegetation cover. All paleosols of the investigated archives show late Holocene ages which point to an environmental turning point around 3 ka. Since then, the Neoglacial period started with cooler climate conditions and periglacial processes intensified again. Recognizable glacier advances occurred during the Little Ice Age several centuries ago. Since then, global climate change leads to warmer and more arid conditions. During the late Holocene, a new period of strong geomorphological activity started and huge quantities of aeolian, colluvial and fluvial sediment accumulated. These intensified soil relocation processes cannot be explained exclusively by climate change because there are no explicit indications found in the palynological and lacustrine records of Mongolia. This discrepancy suggests that the additional factor of human impact has to be considered, which amplified the climate signal on the landscape. Simultaneously, when the enhanced geomorphological processes occurred, the prehistoric people changed from hunting and gathering to livestock husbandry. A first

  16. Identification of sources of tar balls deposited along the Goa coast, India, using fingerprinting techniques.

    PubMed

    Suneel, V; Vethamony, P; Zakaria, M P; Naik, B G; Prasad, K V S R

    2013-05-15

    Deposition of tar balls along the coast of Goa, India is a common phenomenon during the southwest monsoon. Representative tar ball samples collected from various beaches of Goa and one Bombay High (BH) crude oil sample were subjected to fingerprint analysis based on diagnostic ratios of n-alkane, biomarkers of pentacyclic tri-terpanes and compound specific stable carbon isotope (δ¹³C) analysis to confirm the source. The results were compared with the published data of Middle East Crude Oil (MECO) and South East Asian Crude Oil (SEACO). The results revealed that the tar balls were from tanker-wash derived spills. The study also confirmed that the source is not the BH, but SEACO. The present study suggests that the biomarkers of alkanes and hopanes coupled with stable carbon isotope analysis act as a powerful tool for tracing the source of tar balls, particularly when the source specific biomarkers fail to distinguish the source. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Ubiquitous tar balls with a California-source signature on the shorelines of Prince William Sound, Alaska

    USGS Publications Warehouse

    Kvenvolden, K.A.; Hostettler, F.D.; Carlson, P.R.; Rapp, J.B.; Threlkeld, C.N.; Warden, A.

    1995-01-01

    Although the shorelines of Prince William Sound still bear traces of the 1989 Exxon Valdez oil spill, most of the flattened tar balls that can be found today on these shorelines are not residues of Exxon Valdez oil. Instead, the carbon-isotopic and hydrocarbon-biomarker signatures of 61 tar ball samples, collected from shorelines throughout the northern and western parts of the sound, are all remarkably similar and have characteristics consistent with those of oil products that originated from the Monterey Formation source rocks of California. The carbon-isotopic compositions of the tar balls are all closely grouped (??13CPDB = -23.7 ?? 0.2???), within the range found in crude oils from those rocks, but are distinct from isotopic compositions of 28 samples of residues from the Exxon Valdez oil spill (??13CPDB = -29.4 ?? 0.1???). Likewise, values for selected biomarker ratios in the tar balls are all similar but distinct from values of residues from the 1989 oil spill. Carbon-isotopic and biomarker signatures generally relate the tar balls to oil products used in Alaska before ???1970 for construction and pavements. How these tar balls with such similar geochemical characteristics became so widely dispersed throughout the northern and western parts of the sound is not known with certainty, but the great 1964 Alaska earthquake was undoubtedly an important trigger, causing spills from ruptured storage facilities of California-sourced asphalt and fuel oil into Prince William Sound.

  18. Microplastic and tar pollution on three Canary Islands beaches: An annual study.

    PubMed

    Herrera, A; Asensio, M; Martínez, I; Santana, A; Packard, T; Gómez, M

    2018-04-01

    Marine debris accumulation was analyzed from three exposed beaches of the Canary Islands (Lambra, Famara and Las Canteras). Large microplastics (1-5mm), mesoplastics (5-25mm) and tar pollution were assessed twice a month for a year. There was great spatial and temporal variability in the Canary Island coastal pollution. Seasonal patterns differed at each location, marine debris concentration depended mainly of local-scale wind and wave conditions. The most polluted beach was Lambra, a remote beach infrequently visited. The types of debris found were mainly preproduction resin pellets, plastic fragments and tar, evidencing that pollution was not of local origin, but it cames from the open sea. The levels of pollution were similar to those of highly industrialized and contaminated regions. This study corroborates that the Canary Islands are an area of accumulation of microplastics and tar rafted from the North Atlantic Ocean by the southward flowing Canary Current. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Numerical simulation of vortex pyrolysis reactors for condensable tar production from biomass

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

    Miller, R.S.; Bellan, J.

    1998-08-01

    A numerical study is performed in order to evaluate the performance and optimal operating conditions of vortex pyrolysis reactors used for condensable tar production from biomass. A detailed mathematical model of porous biomass particle pyrolysis is coupled with a compressible Reynolds stress transport model for the turbulent reactor swirling flow. An initial evaluation of particle dimensionality effects is made through comparisons of single- (1D) and multi-dimensional particle simulations and reveals that the 1D particle model results in conservative estimates for total pyrolysis conversion times and tar collection. The observed deviations are due predominantly to geometry effects while directional effects frommore » thermal conductivity and permeability variations are relatively small. Rapid ablative particle heating rates are attributed to a mechanical fragmentation of the biomass particles that is modeled using a critical porosity for matrix breakup. Optimal thermal conditions for tar production are observed for 900 K. Effects of biomass identity, particle size distribution, and reactor geometry and scale are discussed.« less

  20. How High is that Dune? A Comparison of Methods Used to Constrain the Morphometry of Aeolian Bedforms on Mars

    NASA Technical Reports Server (NTRS)

    Bourke, M.; Balme, M.; Beyer, R. A.; Williams, K. K.

    2004-01-01

    Methods traditionally used to estimate the relative height of surface features on Mars include: photoclinometry, shadow length and stereography. The MOLA data set enables a more accurate assessment of the surface topography of Mars. However, many small-scale aeolian bedforms remain below the sample resolution of the MOLA data set. In response to this a number of research teams have adopted and refined existing methods and applied them to high resolution (2-6 m/pixel) narrow angle MOC satellite images. Collectively, the methods provide data on a range of morphometric parameters (many not previously available for dunes on Mars). These include dune height, width, length, surface area, volume, longitudinal and cross profiles). This data will facilitate a more accurate analysis of aeolian bedforms on Mars. In this paper we undertake a comparative analysis of methods used to determine the height of aeolian dunes and ripples.

  1. Understanding the fate and transport of petroleum hydrocarbons from coal tar within gasholders.

    PubMed

    Coulon, Frédéric; Orsi, Roberto; Turner, Claire; Walton, Chris; Daly, Paddy; Pollard, Simon J T

    2009-02-01

    Coal tars have been identified as posing a threat to human health due to their toxic, mutagenic and carcinogenic characteristics. Workers involved in former gasholders decommissioning are potentially exposed to relevant concentrations of volatile and semi-volatile hydrocarbons upon opening up derelict tanks and during tar excavation/removal. While information on contaminated sites air-quality and its implications on medium-long term exposure is available, acute exposure issues associated with the execution of critical tasks are less understood. Calculations indicated that the concentration of a given contaminant in the gasholder vapour phase only depends on the coal tar composition, being only barely affected by the presence of water in the gasholder and the tar volume/void space ratio. Fugacity modelling suggested that risk-critical compounds such as benzene, naphthalene and other monocyclic and polycyclic aromatic hydrocarbons may gather in the gasholder air phase at significant concentrations. Gasholder emissions were measured on-site and compared with the workplace exposure limits (WELs) currently in use in UK. While levels for most of the toxic compounds were far lower than WELs, benzene air-concentrations where found to be above the accepted threshold. In addition due to the long exposure periods involved in gasholder decommissioning and the significant contribution given by naphthalene to the total coal tar vapour concentration, the adoption of a WEL for naphthalene may need to be considered to support operators in preventing human health risk at the workplace. The Level I fugacity approach used in this study demonstrated its suitability for applications to sealed environments such as gasholders and its further refining could provide a useful tool for land remediation risk assessors.

  2. DeepMirTar: a deep-learning approach for predicting human miRNA targets.

    PubMed

    Wen, Ming; Cong, Peisheng; Zhang, Zhimin; Lu, Hongmei; Li, Tonghua

    2018-06-01

    MicroRNAs (miRNAs) are small noncoding RNAs that function in RNA silencing and post-transcriptional regulation of gene expression by targeting messenger RNAs (mRNAs). Because the underlying mechanisms associated with miRNA binding to mRNA are not fully understood, a major challenge of miRNA studies involves the identification of miRNA-target sites on mRNA. In silico prediction of miRNA-target sites can expedite costly and time-consuming experimental work by providing the most promising miRNA-target-site candidates. In this study, we reported the design and implementation of DeepMirTar, a deep-learning-based approach for accurately predicting human miRNA targets at the site level. The predicted miRNA-target sites are those having canonical or non-canonical seed, and features, including high-level expert-designed, low-level expert-designed, and raw-data-level, were used to represent the miRNA-target site. Comparison with other state-of-the-art machine-learning methods and existing miRNA-target-prediction tools indicated that DeepMirTar improved overall predictive performance. DeepMirTar is freely available at https://github.com/Bjoux2/DeepMirTar_SdA. lith@tongji.edu.cn, hongmeilu@csu.edu.cn. Supplementary data are available at Bioinformatics online.

  3. Human immunodeficiency virus type 1 LTR TATA and TAR region sequences required for transcriptional regulation.

    PubMed Central

    Garcia, J A; Harrich, D; Soultanakis, E; Wu, F; Mitsuyasu, R; Gaynor, R B

    1989-01-01

    The human immunodeficiency virus (HIV) type 1 LTR is regulated at the transcriptional level by both cellular and viral proteins. Using HeLa cell extracts, multiple regions of the HIV LTR were found to serve as binding sites for cellular proteins. An untranslated region binding protein UBP-1 has been purified and fractions containing this protein bind to both the TAR and TATA regions. To investigate the role of cellular proteins binding to both the TATA and TAR regions and their potential interaction with other HIV DNA binding proteins, oligonucleotide-directed mutagenesis of both these regions was performed followed by DNase I footprinting and transient expression assays. In the TATA region, two direct repeats TC/AAGC/AT/AGCTGC surround the TATA sequence. Mutagenesis of both of these direct repeats or of the TATA sequence interrupted binding over the TATA region on the coding strand, but only a mutation of the TATA sequence affected in vivo assays for tat-activation. In addition to TAR serving as the site of binding of cellular proteins, RNA transcribed from TAR is capable of forming a stable stem-loop structure. To determine the relative importance of DNA binding proteins as compared to secondary structure, oligonucleotide-directed mutations in the TAR region were studied. Local mutations that disrupted either the stem or loop structure were defective in gene expression. However, compensatory mutations which restored base pairing in the stem resulted in complete tat-activation. This indicated a significant role for the stem-loop structure in HIV gene expression. To determine the role of TAR binding proteins, mutations were constructed which extensively changed the primary structure of the TAR region, yet left stem base pairing, stem energy and the loop sequence intact. These mutations resulted in decreased protein binding to TAR DNA and defects in tat-activation, and revealed factor binding specifically to the loop DNA sequence. Further mutagenesis which inverted

  4. The geomorphology and evolution of aeolian landforms within a river valley in a semi-humid environment: A case study from Mainling Valley, Qinghai-Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Zhou, Na; Zhang, Chun-Lai; Wu, Xiao-Xu; Wang, Xun-ming; Kang, Li-qiang

    2014-11-01

    This paper systematically analyzes a valley's aeolian landforms in a semi-humid region and presents a model of its contemporary evolution. Mainling Valley of the Yarlung Zangbo River on the Qinghai-Tibet Plateau was chosen as the case study for the analysis of morphometric characteristics and the evolution sequence of aeolian landforms via field data and remote sensing images. The aeolian landforms were primarily composed of aeolian sand belts on river terraces and dunes (sheets) on hillside slopes. Three types of aeolian sand belts were identified based on their dune types. In type I belts, an erosive air stream combined with relatively high vegetation cover (10%) produced sparsely distributed parabolic dunes with a high variability of dune heights; in type II belts, the continual reworking by the erosive air stream in combination with low vegetation cover (3%) formed more densely distributed barchans and transitional dunes with a moderate variability of dune heights; and in type III belts, the gradual evolution from an erosive sand-laden air stream to a saturated sand-laden air stream in combination with low vegetation cover (2%) produced the densest crescentic dunefields but with the least variability in dune heights. Dune sizes increase, dune shapes become uniform, and dune distribution becomes close from type I to III belts. Lateral linking and merging of the dunes were also observed within the belts. Together this evidence indicates that an evolution sequence may exist. Aeolian dunefields in the belt appear to evolve from embryonic parabolic dunefields to adolescent barchan dunefields and, subsequently, to mature compound crescentic dunefields. As the aeolian sand belt evolves into the mature stage, sand accumulations at the foot of the mountain valley can be steps for sand accumulation on valley-side slopes.

  5. A new record of late Pliocene-early Pleistocene aeolian loess-red clay deposits from the western Chinese Loess Plateau and its palaeoenvironmental implications

    NASA Astrophysics Data System (ADS)

    Zan, Jinbo; Fang, Xiaomin; Zhang, Weilin; Yan, Maodu; Zhang, Dawen

    2018-04-01

    The loess-red clay sequences in northern China provide high-resolution terrestrial records of Asian monsoon evolution and aridification of the Asian interior. To date, however, aeolian deposits of late Pliocene-early Pleistocene age (3.5-2.4 Ma) have only rarely been reported from the western Chinese Loess Plateau (CLP), which significantly hinders our understanding of the distribution of aeolian deposits and the palaeoenvironmental evolution of the region. Here, we present magnetostratigraphic, lithologic and magnetic susceptibility results for two recently-drilled boreholes from the north bank of Baxie River, central Linxia Basin, which are highly correlative with those of the loess-red clay deposits spanning the interval from 3.6 to 2.4 Ma in the eastern CLP. Our results provide the first direct evidence for the occurrence of late Pliocene-early Pleistocene aeolian deposits in the western CLP and provide new insights into the distribution of aeolian deposits in northern China. The spatial coherence of the magnetic susceptibility fluctuations further indicates that magnetic susceptibility is a powerful tool for stratigraphic correlation of late Pliocene aeolian deposits in the western CLP. In addition, our results demonstrate that erosional events may have occurred in the early or middle Pleistocene, and they may provide new insights into the reasons for the absence of loess-red clay deposits from 3.5 to 2.4 Ma in most parts of the western CLP.

  6. Aeolian Grain Evolution on Mars: Implications for Regolith Origins

    NASA Astrophysics Data System (ADS)

    Sullivan, R. J.; Cabrol, N. A.; Golombek, M.; Herkenhoff, K. E.; Landis, G.; Mer Athena Science Team

    2010-12-01

    Early wind tunnel experiments and the Viking Lander experience led to concepts of grain evolution and regolith development on Mars. Wind tunnel experiments showed that 100-150 μm grains are easiest to entrain on Mars, but at 10 times higher wind speeds than on Earth. Even if trajectory speeds of martian saltating grains achieve smaller fractions of entraining wind speeds than on Earth, kinetic energies of these grains would be much higher, with greater potential for damage to the grains during return collisions with the particle bed. On this basis Sagan et al. [1977] JGR 82, 28, 4430 proposed that aeolian grain evolution on Mars followed a “kamikaze” pattern in which an initially coarse grain, entrained only relatively rarely by the strongest winds, would be abraded by high kinetic energy impacts and migrate through successively smaller size-frequencies at an ever-increasing rate (as entrainment became easier and thus more likely) until the grain was essentially turned to dust. On this basis it was proposed that sand-sized grains might be relatively short-lived and perhaps rare on Mars. MER observations motivate adjustments to these concepts, with implications for origins of martian regolith reworked by wind. Along both MER traverses, on opposite sides of the planet, regolith is volumetrically dominated by very fine sand mixed with unresolved finer grains. Sorting probably is poor, based on weakly cohesive remolding by rover wheel cleats. The size-frequency of this material, even if not precisely known, is consistent with grains that have evolved by attrition to sizes smaller than the most easily-moved 100-150 μm interval, to where entrainment becomes more difficult due to the increasing relative importance of inter-particle surface forces. At these smaller sizes also, kinetic energies have been reduced proportionally by the cube of the particle radius, so grain-to-grain attrition is less effective for further evolution to even smaller grain sizes

  7. Upgrading producer gas quality from rubber wood gasification in a radio frequency tar thermocatalytic treatment reactor.

    PubMed

    Anis, Samsudin; Zainal, Z A

    2013-12-01

    This study focused on improving the producer gas quality using radio frequency (RF) tar thermocatalytic treatment reactor. The producer gas containing tar, particles and water was directly passed at a particular flow rate into the RF reactor at various temperatures for catalytic and thermal treatments. Thermal treatment generates higher heating value of 5.76 MJ Nm(-3) at 1200°C. Catalytic treatments using both dolomite and Y-zeolite provide high tar and particles conversion efficiencies of about 97% on average. The result also showed that light poly-aromatic hydrocarbons especially naphthalene and aromatic compounds particularly benzene and toluene were still found even at higher reaction temperatures. Low energy intensive RF tar thermocatalytic treatment was found to be effective for upgrading the producer gas quality to meet the end user requirements and increasing its energy content. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Determination of the conformational ensemble of the TAR RNA by X-ray scattering interferometry

    PubMed Central

    Walker, Peter

    2017-01-01

    Abstract The conformational ensembles of structured RNA's are crucial for biological function, but they remain difficult to elucidate experimentally. We demonstrate with HIV-1 TAR RNA that X-ray scattering interferometry (XSI) can be used to determine RNA conformational ensembles. X-ray scattering interferometry (XSI) is based on site-specifically labeling RNA with pairs of heavy atom probes, and precisely measuring the distribution of inter-probe distances that arise from a heterogeneous mixture of RNA solution structures. We show that the XSI-based model of the TAR RNA ensemble closely resembles an independent model derived from NMR-RDC data. Further, we show how the TAR RNA ensemble changes shape at different salt concentrations. Finally, we demonstrate that a single hybrid model of the TAR RNA ensemble simultaneously fits both the XSI and NMR-RDC data set and show that XSI can be combined with NMR-RDC to further improve the quality of the determined ensemble. The results suggest that XSI-RNA will be a powerful approach for characterizing the solution conformational ensembles of RNAs and RNA-protein complexes under diverse solution conditions. PMID:28108663

  9. Determination of the conformational ensemble of the TAR RNA by X-ray scattering interferometry.

    PubMed

    Shi, Xuesong; Walker, Peter; Harbury, Pehr B; Herschlag, Daniel

    2017-05-05

    The conformational ensembles of structured RNA's are crucial for biological function, but they remain difficult to elucidate experimentally. We demonstrate with HIV-1 TAR RNA that X-ray scattering interferometry (XSI) can be used to determine RNA conformational ensembles. X-ray scattering interferometry (XSI) is based on site-specifically labeling RNA with pairs of heavy atom probes, and precisely measuring the distribution of inter-probe distances that arise from a heterogeneous mixture of RNA solution structures. We show that the XSI-based model of the TAR RNA ensemble closely resembles an independent model derived from NMR-RDC data. Further, we show how the TAR RNA ensemble changes shape at different salt concentrations. Finally, we demonstrate that a single hybrid model of the TAR RNA ensemble simultaneously fits both the XSI and NMR-RDC data set and show that XSI can be combined with NMR-RDC to further improve the quality of the determined ensemble. The results suggest that XSI-RNA will be a powerful approach for characterizing the solution conformational ensembles of RNAs and RNA-protein complexes under diverse solution conditions. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  10. Remedial Investigation Work Plan for Chestnut Ridge Operable Unit 1 (Chestnut Ridge Security Pits) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

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

    Not Available

    1994-03-01

    This document outlines the activities necessary to conduct a Remedial Investigation (RI) of the Chestnut Ridge Security Pits (CRSP) at the Oak Ridge Y-12 Plant. The CRSP, also designated Chestnut Ridge Operable Unit (OU) 1, is one of four OUs along Chestnut Ridge on the Oak Ridge Reservation (ORR). The purpose of the RI is to collect data to (1) evaluate the nature and extent of known and suspected contaminants, (2) support an Ecological Risk Assessment (ERA) and a Human Health Risk Assessment (HHRA), (3) support the feasibility study in the development and analysis of remedial alternatives, and (4) ultimately,more » develop a Record of Decision (ROD) for the site. This chapter summarizes the regulatory background of environmental investigation on the ORR and the approach currently being followed and provides an overview of the RI to be conducted at the CRSP. Subsequent chapters provide details on site history, sampling activities, procedures and methods, quality assurance (QA), health and safety, and waste management related to the RI.« less

  11. SULFUR TOLERANT CATALYSTS FOR BIOMASS TAR REMOVAL - PHASE I

    EPA Science Inventory

    In this Small Business Innovation Research (SBIR) project, NexTech Materials proposes a catalytic reforming approach to remove waste tar from gasified biomass on nickel-based catalysts. Biomass gasification is a potential renewable route to producing electricity, liquid fue...

  12. A tribute to Michael R. Raupach for contributions to aeolian fluid dynamics

    USDA-ARS?s Scientific Manuscript database

    Since the early work of Bagnold in the 1940s, aeolian research has grown to become a major integral part of earth-system studies. Many individuals have contributed to this development, and Dr. Michael R. Raupach (MR2, 1950 – 2015) was one of the most outstanding. MR2 worked for about a decade (1985 ...

  13. [Nutrient contents and microbial populations of aeolian sandy soil in Sanjiangyuan region of Qinghai Province].

    PubMed

    Lin, Chao-feng; Chen, Zhan-quan; Xue, Quan-hong; Lai, Hang-xian; Chen, Lai-sheng; Zhang, Deng-shan

    2007-01-01

    Sanjiangyuan region (the headstream of three rivers) in Qinghai Province of China is the highest and largest inland alpine wetland in the world. The study on the nutrient contents and microbial populations of aeolian sandy soils in this region showed that soil organic matter content increased with the evolution of aeolian sand dunes from un-stabilized to stabilized state, being 5.9 and 3.8 times higher in stabilized sand dune than in mobile and semi-stabilized sand dunes, respectively. Soil nitrogen and phosphorus contents increased in line with the amount of organic matter, while potassium content and pH value varied slightly. The microbial populations changed markedly with the development of vegetation, fixing of mobile sand, and increase of soil nutrients. The quantities of soil bacteria, fungi and actinomycetes were 4.0 and 2.8 times, 19.6 and 6.3 times, and 12.4 and 2.6 times higher in stabilized and semi-stabilized sand dunes than in mobile sand dune, respectively, indicating that soil microbial bio-diversity was increased with the evolution of aeolian sand dunes from mobile to stabilized state. In addition, the quantities of soil microbes were closely correlated with the contents of soil organic matter, total nitrogen, and available nitrogen and phosphorus, but not correlated with soil total phosphorus, total and available potassium, or pH value.

  14. 2007 Weather and Aeolian Sand-Transport Data from the Colorado River Corridor, Grand Canyon, Arizona

    USGS Publications Warehouse

    Draut, Amy E.; Andrews, Timothy; Fairley, Helen C.; Brown, Christopher R.

    2009-01-01

    Weather data constitute an integral part of ecosystem monitoring in the Colorado River corridor and are particularly valuable for understanding processes of landscape change that contribute to the stability of archeological sites. Data collected in 2007 are reported from nine weather stations in the Colorado River corridor through Grand Canyon, Ariz. The stations were deployed in February and March 2007 to measure wind speed and direction, rainfall, air temperature, relative humidity, and barometric pressure. Sand traps near each weather station collect windblown sand, from which daily aeolian sand-transport rates are calculated. The data reported here were collected as part of an ongoing study to test and evaluate methods for quantifying processes that affect the physical integrity of archeological sites along the river corridor; as such, these data can be used to identify rainfall events capable of causing gully incision and to predict likely transport pathways for aeolian sand, two landscape processes integral to the preservation of archeological sites. Weather data also have widespread applications to other studies of physical, cultural, and biological resources in Grand Canyon. Aeolian sand-transport data reported here, collected in the year before the March 2008 High-Flow Experiment (HFE) at Glen Canyon Dam, represent baseline data against which the effects of the 2008 HFE on windblown sand will be compared in future reports.

  15. Influence of the presence of PAHs and coal tar on naphthalene sorption in soils

    NASA Astrophysics Data System (ADS)

    Bayard, Rémy; Barna, Ligia; Mahjoub, Borhane; Gourdon, Rémy

    2000-11-01

    The mobility of the most water-soluble polynuclear aromatic hydrocarbons (PAHs) such as naphthalene in contaminated soils from manufactured gas plant (MGP) sites or other similar sites is influenced not only by the naturally occurring soil organic matter (SOM) but also, and in many cases mostly, by the nature and concentration of coal tar xenobiotic organic matter (XOM) and other PAH molecules present in the medium under various physical states. The objective of the present study was to quantify the effects of these factors using batch experiments, in order to simulate naphthalene transport in soil-tar-water systems using column experiments. Naphthalene sorption was studied in the presence of (i) solid coal tar particles, (ii) phenanthrene supplied as pure crystals, in the aqueous solution or already sorbed onto the soil, (iii) fluoranthene as pure crystals, and (iv) an aqueous solution of organic molecules extracted from a liquid tar. All experiments were conducted under abiotic conditions using short naphthalene/sorbent contact times of 24-60 h. Although these tests do not reflect true equilibrium conditions which usually take more time to establish, they were used to segregate relatively rapid sorption phenomena ("pseudo equilibrium") from slow sorption and other aging phenomena. For longer contact times, published data have shown that experimental biases due to progressive changes in the characteristics of the soil and the solution may drastically modify the affinity of the solutes for the soil. Slow diffusion in the microporosity and in dense organic phases may also become significant over the long term, along with some irreversible aging phenomena which have not been addressed in this work. Results showed that PAHs had no effect on naphthalene sorption when present in the aqueous solution or as pure crystals, due to their low solubility in water. Adsorbed phenanthrene was found to reduce naphthalene adsorption only when present at relatively high

  16. Aeolian dust nutrient contributions increase with substrate age in semi-arid ecosystems

    NASA Astrophysics Data System (ADS)

    Coble, A. A.; Hart, S. C.; Ketterer, M. E.; Newman, G. S.

    2013-12-01

    Rock-derived nutrients supplied by mineral weathering become depleted over time, and without an additional nutrient source the ecosystem may eventually regress or reach a terminal steady state. Previous studies have demonstrated that aeolian dust act as parent materials of soils and important nutrients to plants in arid regions, but the relative importance of these exogenous nutrients to the function of dry ecosystems during soil development is uncertain. Here, using strontium isotopes as a tracer and a well-constrained, three million year old substrate age gradient, we show that aeolian-derived nutrients become increasingly important to plant-available soil pools and tree (Pinus edulis) growth during the latter stages of soil development in a semi-arid climate. Furthermore, the depth of nutrient uptake increased on older substrates, suggesting that trees in arid regions acquire nutrients from greater depths as ecosystem development progresses presumably in response to nutrient depletion in the more weathered surface soils. Our results contribute to the unification of biogeochemical theory by demonstrating the similarity in roles of atmospheric nutrient inputs during ecosystem development across contrasting climates.

  17. 33 CFR 165.927 - Safety Zone; St. Louis River, Duluth/Interlake Tar Remediation Site, Duluth, MN.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Safety Zone; St. Louis River, Duluth/Interlake Tar Remediation Site, Duluth, MN. 165.927 Section 165.927 Navigation and Navigable... Coast Guard District § 165.927 Safety Zone; St. Louis River, Duluth/Interlake Tar Remediation Site...

  18. PAH volatilization following application of coal-tar-based pavement sealant

    USGS Publications Warehouse

    Van Metre, Peter C.; Majewski, Michael S.; Mahler, Barbara J.; Foreman, William T.; Braun, Christopher L.; Wilson, Jennifer T.; Burbank, Teresa L.

    2012-01-01

    Coal-tar-based pavement sealants, a major source of PAHs to urban water bodies, have recently been identified as a source of volatile PAHs to the atmosphere. We tracked the volatilization of PAHs for 1 year after application of a coal-tar-based pavement sealant by measuring gas-phase PAH concentrations above the pavement surface and solid-phase PAH concentrations in sealant scraped from the surface. Gas-phase concentrations at two heights (0.03 and 1.28 m) and wind speed were used to estimate volatilization flux. The sum of the concentrations of eight frequently detected PAHs (ΣPAH8) in the 0.03-m sample 1.6 h after application (297,000 ng m-3) was about 5000 times greater than that previously reported for the same height above unsealed parking lots (66 ng m-3). Flux at 1.6 h after application was estimated at 45,000 μg m-2 h-1 and decreased rapidly during the 45 days after application to 160 μg m-2 h-1. Loss of PAHs from the adhered sealant also was rapid, with about a 50% decrease in solid-phase ΣPAH8 concentration over the 45 days after application. There was general agreement, given the uncertainties, in the estimated mass of ΣPAH8 lost to the atmosphere on the basis of air sampling (2–3 g m-2) and adhered sealant sampling (6 g m-2) during the first 16 days after application, translating to a loss to the atmosphere of one-quarter to one-half of the PAHs in the sealcoat product. Combining the estimated mass of ΣPAH8 released to the atmosphere with a national-use estimate of coal-tar-based sealant suggests that PAH emissions from new coal-tar-based sealcoat applications each year (~1000 Mg) are larger than annual vehicle emissions of PAHs for the United States.

  19. Late Pleistocene and Holocene aeolian sedimentation in Gonghe Basin, northeastern Qinghai-Tibetan Plateau: Variability, processes, and climatic implications

    NASA Astrophysics Data System (ADS)

    Qiang, Mingrui; Jin, Yanxiang; Liu, Xingxing; Song, Lei; Li, Hao; Li, Fengshan; Chen, Fahu

    2016-01-01

    Although stratigraphic sequences of aeolian deposits in dryland areas have long been recognized as providing information about past environments, the exact nature of the environmental processes they reflect remains unclear. Here, we report the results of a detailed investigation of eight outcrop sections in the Gonghe Basin, northeastern Qinghai-Tibetan Plateau. Measurements of sediment grain-size and chemical composition indicate that the deposits are primarily of aeolian origin, consisting of interbedded, well-sorted sand, silty sand, loess and/or palaeosol; however, their occurrence varies from site to site. Fossil dune sands mainly occur in or close to the currently stabilized or semi-stabilized dune fields, whereas loess is distributed along the downwind marginal areas. This pattern of basin-scale differentiation was controlled mainly by spatial variability of sediment supply due to the antecedent sedimentary patterns within the basin. Together with previously-published optically stimulated luminescence (OSL) ages, 24 new OSL dates are used to elucidate the history of aeolian activity and its relationship to climatic changes. There is no apparent relationship between past dune activity and downwind loess deposits. Deposition of silty sand probably occurred during past phases of windy, dry and cold climate in the Late Pleistocene. However, climatic factors alone cannot explain the occurrence of silty sand deposition. This is because the deposition of silty sand was always preceded by episodes of fluvial deposition prior to river incision, thereby indicating the importance of an 'activated' sediment supply associated with fluvial processes. Deposition of well-sorted sand occurred episodically, not only during the Late Pleistocene, but also during the early- to mid-Holocene. Vegetation conditions, controlled either by the occurrence of intervals of moisture deficit during the Late Pleistocene or by changes in the balance between precipitation and

  20. Supercritical-Fluid Extraction of Oil From Tar Sands

    NASA Technical Reports Server (NTRS)

    Compton, L. E.

    1982-01-01

    New supercritical solvent mixtures have been laboratory-tested for extraction of oil from tar sands. Mixture is circulated through sand at high pressure and at a temperature above critical point, dissolving organic matter into the compressed gas. Extract is recovered from sand residues. Low-temperature super-critical solvents reduce energy consumption and waste-disposal problems.

  1. The search for a source rock for the giant Tar Sand triangle accumulation, southeastern Utah

    USGS Publications Warehouse

    Huntoon, J.E.; Hansley, P.L.; Naeser, N.D.

    1999-01-01

    A large proportion (about 36%) of the world's oil resource is contained in accumulations of heavy oil or tar. In these large deposits of degraded oil, the oil in place represents only a fraction of what was present at the time of accumulation. In many of these deposits, the source of the oil is unknown, and the oil is thought to have migrated over long distances to the reservoirs. The Tar Sand triangle in southeastern Utah contains the largest tar sand accumulation in the United States, with 6.3 billion bbl of heavy oil estimated to be in place. The deposit is thought to have originally contained 13-16 billion bbl prior to the biodegradation, water washing, and erosion that have taken place since the middle - late Tertiary. The source of the oil is unknown. The tar is primarily contained within the Lower Permian White Rim Sandstone, but extends into permeable parts of overlying and underlying beds. Oil is interpreted to have migrated into the White Rim sometime during the Tertiary when the formation was at a depth of approximately 3500 m. This conclusion is based on integration of fluid inclusion analysis, time-temperature reconstruction, and apatite fission-track modeling for the White Rim Sandstone. Homogenization temperatures cluster around 85-90??C for primary fluid inclusions in authigenic, nonferroan dolomite in the White Rim. The fluid inclusions are associated with fluorescent oil-bearing inclusions, indicating that dolomite precipitation was coeval with oil migration. Burial reconstruction suggests that the White Rim Sandstone reached its maximum burial depth from 60 to 24 Ma, and that maximum burial was followed by unroofing from 24 to 0 Ma. Time-temperature modeling indicates that the formation experienced temperatures of 85-90??C from about 35 to 40 Ma during maximum burial. Maximum formation temperatures of about 105-110??C were reached at about 24 Ma, just prior to unroofing. Thermal modeling is used to examine the history of potential source rocks

  2. Aeolian saltation on Mars at low wind speeds

    NASA Astrophysics Data System (ADS)

    Sullivan, R.; Kok, J. F.

    2017-10-01

    Laboratory experiments indicate that the fluid threshold friction speed, u*tf, required to initiate fully developed aeolian saltation is much higher on Mars than on Earth. A discrepancy exists between Mars climate models that do not predict winds this strong and observations that sand-sized particles are indeed moving. This paper describes how wind friction speeds well below u*tf, but above the impact threshold, u*ti, required to sustain saltation, can initiate sustained saltation on Mars, but at relatively low flux. Numerical experiments indicate that a sand grain on Mars mobilized sporadically between u*ti and u*tf will develop, over fetch lengths longer than generally available within low-pressure wind tunnels, trajectories capable of splashing grains that propagate saltation and collectively form a cluster of saltating grains that migrate downwind together. The passage of a saltation cluster should leave behind a narrow zone of affected surface grains. The cumulative effect of many clusters represents a low-flux phenomenon that should produce slow changes to aeolian bedforms over periods in which winds remain close to u*ti and never or rarely reach u*tf. Field evidence from small impact ripples along rover traverses is consistent with effects of saltation at these low friction speeds, without obvious evidence for events ≥u*tf. The potential utility of this grain mobility process is that it can operate entirely at more common winds well below u*tf and so help explain widespread sand movements observed on Mars wherever evidence might be mostly absent for u*tf being exceeded.

  3. Impact of Genetic Variations in HIV-1 Tat on LTR-Mediated Transcription via TAR RNA Interaction.

    PubMed

    Ronsard, Larance; Ganguli, Nilanjana; Singh, Vivek K; Mohankumar, Kumaravel; Rai, Tripti; Sridharan, Subhashree; Pajaniradje, Sankar; Kumar, Binod; Rai, Devesh; Chaudhuri, Suhnrita; Coumar, Mohane S; Ramachandran, Vishnampettai G; Banerjea, Akhil C

    2017-01-01

    HIV-1 evades host defense through mutations and recombination events, generating numerous variants in an infected patient. These variants with an undiminished virulence can multiply rapidly in order to progress to AIDS. One of the targets to intervene in HIV-1 replication is the trans -activator of transcription (Tat), a major regulatory protein that transactivates the long terminal repeat promoter through its interaction with trans -activation response (TAR) RNA. In this study, HIV-1 infected patients ( n = 120) from North India revealed Ser46Phe (20%) and Ser61Arg (2%) mutations in the Tat variants with a strong interaction toward TAR leading to enhanced transactivation activities. Molecular dynamics simulation data verified that the variants with this mutation had a higher binding affinity for TAR than both the wild-type Tat and other variants that lacked Ser46Phe and Ser61Arg. Other mutations in Tat conferred varying affinities for TAR interaction leading to differential transactivation abilities. This is the first report from North India with a clinical validation of CD4 counts to demonstrate the influence of Tat genetic variations affecting the stability of Tat and its interaction with TAR. This study highlights the co-evolution pattern of Tat and predominant nucleotides for Tat activity, facilitating the identification of genetic determinants for the attenuation of viral gene expression.

  4. Method of producing drive fluid in situ in tar sands formations

    DOEpatents

    Mudunuri, Ramesh Raju; Jaiswal, Namit; Vinegar, Harold J.; Karanikas, John Michael

    2010-03-23

    Methods of treating a tar sands formation are described herein. Methods for treating a tar sands may include providing heat to at least part of a hydrocarbon layer in the formation from one or more heaters located in the formation. The heat may be allowed to transfer from the heaters to at least a portion of the formation such that a drive fluid is produced in situ in the formation. The drive fluid may move at least some mobilized, visbroken, and/or pyrolyzed hydrocarbons from a first portion of the formation to a second portion of the formation. At least some of the mobilized, visbroken, and/or pyrolyzed hydrocarbons may be produced from the formation.

  5. Marketing 'less harmful, low-tar' cigarettes is a key strategy of the industry to counter tobacco control in China.

    PubMed

    Yang, Gonghuan

    2014-03-01

    While the 'low-tar' scheme has been widely recognised as a misleading tactic used by the tobacco industry to deceive the public about the true risks of cigarette smoking, a similar campaign using the slogan of 'less harmful, low tar' was launched by the Chinese tobacco industry, that is, State Tobacco Monopoly Administration/China National Tobacco Corporation and began to gain traction during the last decade. Despite the fact that no sufficient research evidence supports the claims made by the industry that these cigarettes are safer, the Chinese tobacco industry has continued to promote them using various health claims. As a result, the production and sales of 'less harmful, low-tar' cigarettes have increased dramatically since 2000. Recently, a tobacco industry senior researcher, whose main research area is 'less harmful, low-tar' cigarettes, was elected as an Academician to the prestigious Chinese Academy of Engineering for his contribution to developing 'less harmful, low-tar' cigarettes. The tobacco researcher's election caused an outcry from the tobacco control community and the general public in China. This paper discusses the Chinese tobacco industry's 'less harmful, low-tar' initiatives and calls for the Chinese government to stop the execution of this deceptive strategy for tobacco marketing.

  6. Relationship between cigarette format and mouth-level exposure to tar and nicotine in smokers of Russian king-size cigarettes.

    PubMed

    Ashley, Madeleine; Dixon, Mike; Prasad, Krishna

    2014-10-01

    Differences in length and circumference of cigarettes may influence smoker behaviour and exposure to smoke constituents. Superslim king-size (KSSS) cigarettes (17mm circumference versus 25mm circumference of conventional king-size [KS] cigarettes), have gained popularity in several countries, including Russia. Some smoke constituents are lower in machine-smoked KSSS versus KS cigarettes, but few data exist on actual exposure in smokers. We investigated mouth-level exposure (MLE) to tar and nicotine in Russian smokers of KSSS versus KS cigarettes and measured smoke constituents under machine-smoking conditions. MLE to tar was similar for smokers of 1mg ISO tar yield products, but lower for smokers of 4mg and 7mg KSSS versus KS cigarettes. MLE to nicotine was lower in smokers of 4mg KSSS versus KS cigarettes, but not for other tar bands. No gender differences were observed for nicotine or tar MLE. Under International Organization for Standardization, Health Canada Intense and Massachusetts regimes, KSSS cigarettes tended to yield less carbon monoxide, acetaldehyde, nitric oxide, acrylonitrile, benzene, 1,3-butadiene and tobacco-specific nitrosamines, but more formaldehyde, than KS cigarettes. In summary, differences in MLE were observed between cigarette formats, but not systematically across pack tar bands. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  7. Atmospheric dust in modern soil on aeolian sandstone, Colorado Plateau (USA): Variation with landscape position and contribution to potential plant nutrients

    USGS Publications Warehouse

    Reynolds, R.; Neff, J.; Reheis, M.; Lamothe, P.

    2006-01-01

    Rock-derived nutrients in soils originate from both local bedrock and atmospheric dust, including dust from far-distant sources. Distinction between fine particles derived from local bedrock and from dust provides better understanding of the landscape-scale distribution and abundance of soil nutrients. Sandy surficial deposits over dominantly sandstone substrates, covering vast upland areas of the central Colorado Plateau, typically contain 5-40% silt plus clay, depending on geomorphic setting and slope (excluding drainages and depressions). Aeolian dust in these deposits is indicated by the presence of titanium-bearing magnetite grains that are absent in the sedimentary rocks of the region. Thus, contents of far-traveled aeolian dust can be estimated from magnetic properties that primarily reflect magnetite content, such as isothermal remanent magnetization (IRM). Isothermal remanent magnetization was measured on bulk sediment samples taken along two transects in surficial sediment down gentle slopes away from sandstone headwalls. One transect was in undisturbed surficial sediment, the other in a setting that was grazed by domestic livestock until 1974. Calculation of far-traveled dust contents of the surficial deposits is based on measurements of the magnetic properties of rock, surficial deposits, and modern dust using a binary mixing model. At the undisturbed site, IRM-based calculations show a systematic down-slope increase in aeolian dust (ranging from 2% to 18% of the surface soil mass), similar to the down-slope increase in total fines (18-39% of surface soil mass). A combination of winnowing by wind during the past and down-slope movement of sediment likely accounts for the modern distribution of aeolian dust and associated nutrients. At the previously grazed site, dust also increases down slope (5-11%) in sediment with corresponding abundances of 13-25% fines. Estimates of the contributions of aeolian dust to the total soil nutrients range widely

  8. Identification and characterization of a HeLa nuclear protein that specifically binds to the trans-activation-response (TAR) element of human immunodeficiency virus.

    PubMed Central

    Marciniak, R A; Garcia-Blanco, M A; Sharp, P A

    1990-01-01

    Human immunodeficiency virus type 1 RNAs contain a sequence, trans-activation-response (TAR) element, which is required for tat protein-mediated trans-activation of viral gene expression. We have identified a nuclear protein from extracts of HeLa cells that binds to the TAR element RNA in a sequence-specific manner. The binding of this 68-kDa polypeptide was detected by UV cross-linking proteins to TAR element RNA transcribed in vitro. Competition experiments were performed by using a partially purified preparation of the protein to quantify the relative binding affinities of TAR element RNA mutants. The binding affinity of the TAR mutants paralleled the reported ability of those mutants to support tat trans-activation in vivo. We propose that this cellular protein moderates TAR activity in vivo. Images PMID:2333305

  9. Pyrolysis characteristics and kinetics of acid tar waste from crude benzol refining: A thermogravimetry-mass spectrometry analysis.

    PubMed

    Chihobo, Chido H; Chowdhury, Arindrajit; Kuipa, Pardon K; Simbi, David J

    2016-12-01

    Pyrolysis is an attractive thermochemical conversion technology that may be utilised as a safe disposal option for acid tar waste. The kinetics of acid tar pyrolysis were investigated using thermogravimetry coupled with mass spectrometry under a nitrogen atmosphere at different heating rates of 10, 15 and 20 K min -1 The thermogravimetric analysis shows three major reaction peaks centred around 178 °C, 258 °C, and 336 °C corresponding to the successive degradation of water soluble lower molecular mass sulphonic acids, sulphonated high molecular mass hydrocarbons, and high molecular mass hydrocarbons. The kinetic parameters were evaluated using the iso-conversional Kissinger-Akahira-Sunose method. A variation in the activation energy with conversion revealed that the pyrolysis of the acid tar waste progresses through complex multi-step kinetics. Mass spectrometry results revealed a predominance of gases such as hydrogen, methane and carbon monoxide, implying that the pyrolysis of acid tar waste is potentially an energy source. Thus the pyrolysis of acid tar waste may present a viable option for its environmental treatment. There are however, some limitations imposed by the co-evolution of corrosive gaseous components for which appropriate considerations must be provided in both pyrolysis reactor design and selection of construction materials. © The Author(s) 2016.

  10. Social-cognitive remediation in schizophrenia: generalization of effects of the Training of Affect Recognition (TAR).

    PubMed

    Wölwer, Wolfgang; Frommann, Nicole

    2011-09-01

    In the last decade, several social cognitive remediation programs have been developed for use in schizophrenia. Though existing evidence indicates that such programs can improve social cognition, which is essential for successful social functioning, it remains unclear whether the improvements generalize to social cognitive domains not primarily addressed by the intervention and whether the improved test performance transfers into everyday social functioning. The present study investigated whether, beyond its known effects on facial affect recognition, the Training of Affect Recognition (TAR) has effects on prosodic affect recognition, theory of mind (ToM) performance, social competence in a role-play task, and more general social and occupational functioning. Thirty-eight inpatients with a diagnosis of schizophrenia or schizoaffective disorder were randomly assigned to 6 weeks of treatment with the TAR--primarily targeted at facial affect recognition-or Cognitive Remediation Training (CRT)--primarily targeted at neurocognition. Intention-to-treat analyses found significantly larger pre-post improvements with TAR than with CRT in prosodic affect recognition, ToM, and social competence and a trend effect in global social functioning. However, the effects on ToM and social competence were no longer significant in the smaller group of patients who completed treatment according to protocol. Results suggest that TAR effects generalize to other social cognitive domains not primarily addressed. TAR may also enhance social skills and social functioning, although this has to be confirmed. Results are discussed with regard to the need to improve functional outcome in schizophrenia against the background of current evidence from other social cognitive remediation approaches.

  11. Controls on melting at spreading ridges from correlated abyssal peridotite - mid-ocean ridge basalt compositions

    NASA Astrophysics Data System (ADS)

    Regelous, Marcel; Weinzierl, Christoph G.; Haase, Karsten M.

    2016-09-01

    Variations in the volume and major element composition of basalt erupted along the global mid-ocean ridge system have been attributed to differences in mantle potential temperature, mantle composition, or plate spreading rate and lithosphere thickness. Abyssal peridotites, the residues of mantle melting beneath mid-ocean ridges, provide additional information on the melting process, which could be used to test these hypotheses. We compiled a global database of abyssal peridotite compositions averaged over the same ridge segments defined by Gale et al. (2013). In addition, we calculated the distance of each ridge segment to the nearest hotspots. We show that Cr# in spinel in abyssal peridotites is negatively correlated with Na90 in basalts from the same ridge segments on a global scale. Ridge segments that erupt basalts apparently produced by larger degrees of mantle melting are thus underlain by peridotites from which large amounts of melt have been extracted. We find that near-ridge hotspots have a more widespread influence on mid-ocean ridge basalt (MORB) composition and ridge depth than previously thought. However, when these hotspot-influenced ridge segments are excluded, the remaining segments show clear relationships between MORB composition, peridotite composition, and ridge depth with spreading rate. Very slow-spreading ridges (<20 mm/yr) are deeper, erupt basalts with higher Na90, Al90, K90/Ti90, and lower Fe90, Ca90/Al90, and expose peridotites with lower Cr# than intermediate and fast-spreading ridges. We show that away from hotspots, the spreading-rate dependence of the maximum degree of mantle melting inferred from Cr# in peridotites (FM) and the bulk degree of melting inferred from Na90 in basalts (FB) from the same ridge segments is unlikely to be due to variations in mantle composition. Nor can the effects of dynamic mantle upwelling or incomplete melt extraction at low spreading rates satisfactorily explain the observed compositions of abyssal

  12. In situ heat treatment of a tar sands formation after drive process treatment

    DOEpatents

    Vinegar, Harold J.; Stanecki, John

    2010-09-21

    A method for treating a tar sands formation includes providing a drive fluid to a hydrocarbon containing layer of the tar sands formation to mobilize at least some hydrocarbons in the layer. At least some first hydrocarbons from the layer are produced. Heat is provided to the layer from one or more heaters located in the formation. At least some second hydrocarbons are produced from the layer of the formation. The second hydrocarbons include at least some hydrocarbons that are upgraded compared to the first hydrocarbons produced by using the drive fluid.

  13. Cigarettes, lung cancer, and coronary heart disease: the effects of inhalation and tar yield.

    PubMed

    Higenbottam, T; Shipley, M J; Rose, G

    1982-06-01

    Ten-year mortality rates for lung cancer and coronary heart disease have been related to cigarette smoking habits in 17 475 male civil servants aged 40-64 and in sample of 8089 male British residents aged 35-69. Both diseases were more frequent in smokers. Lung cancer rates were higher overall for "non-inhalers", particularly in heavy smokers. Tar yield correlated with the risk of lung cancer in non-inhalers but less so in inhalers. Conversely, coronary deaths were more common among inhalers, and the effect of tar/nicotine yield (such as it was) was confined to inhalers. It appears that there are subtle interactions between the amount smoked, the tar/nicotine yield of the cigarette, and the style of smoking. Thus the effects of a change in cigarette characteristics are hard to predict, and they may be different for respiratory and cardiovascular disease.

  14. Properties of gasification-derived char and its utilization for catalytic tar reforming

    NASA Astrophysics Data System (ADS)

    Qian, Kezhen

    Char is a low-value byproduct of biomass gasification and pyrolysis with many potential applications, such as soil amendment and the synthesis of activated carbon. The overall goal of the proposed research was to develop novel methods to use char derived from gasification for high-value applications in syngas conditioning. The first objective was to investigate effects of gasification condition and feedstock on properties of char derived from fluidized bed gasification. Results show that the surface areas of most of the char were 1--10 m 2/g and increased as the equivalence ratio increased. Char moisture and fixed carbon contents decreased while ash content increased as equivalence ratio increased. The next objective was to study the properties of sorghum and red cedar char derived from downdraft gasifier. Red cedar char contained more aliphatic carbon and o-alkyl carbon than sorghum char. Char derived from downdraft gasification had higher heating values and lower ash contents than char derived from fluidized bed gasification. The gasification reactivity of red cedar char was higher than that of sorghum char. Then, red cedar char based catalysts were developed with different preparation method to reform toluene and naphthalene as model tars. The catalyst prepared with nickel nitrate was found to be better than that with nickel acetate. The nickel particle size of catalyst impregnated with nickel nitrate was smaller than that of catalyst impregnated with nickel acetate. The particle size of catalyst impregnated with nickel acetate decreased by hydrazine reduction. The catalyst impregnated with nickel nitrate had the highest toluene removal efficiency, which was 70%--100% at 600--800 °C. The presence of naphthalene in tar reduced the catalyst efficiency. The toluene conversion was 36--99% and the naphthalene conversion was 37%--93% at 700--900 °C. Finally, effects of atmosphere and pressure on catalytic reforming of lignin-derived tars over the developed catalyst

  15. Recent seasonal variations in arid landscape cover and aeolian sand mobility, Navajo Nation, southwestern U.S.

    USGS Publications Warehouse

    Draut, Amy E.; Redsteer, Margaret Hiza; Amoroso, Lee; Giosan, Liviu; Fuller, Dorian Q.; Nicoll, Kathleen; Flad, Rowan K.; Clift, Peter D.

    2013-01-01

    The socioeconomic impacts of climate change pose problems not only in devel- oping countries but also to residents of arid lands in the United States among marginalized societies with limited economic means. In the Navajo Nation, warming temperatures and recent drought have increased aeolian sediment mobility such that large, migrating sand dunes affect grazing lands, housing, and road access. Dust derived from this region also affects albedo and longevity of the Rocky Mountains snowpack, located downwind. We present initial results from a study that monitors sand transport and vegetation within a 0.2 km2 site in the Navajo lands, measuring the effects of drought on landscape stability since 2009. Sand mobility decreased substantially as 1 year with near-normal monsoon rainfall (2010) somewhat abated a decade-long drought, temporarily doubling vegetation cover. Vegetation that grew during 2010, with adequate rain, died off rapidly during dry conditions in 2011. Short-term increases in rainfall that promote annual, but not perennial, plant growth will not improve landscape stability in the long term. Climate projections suggest that a warmer, drier climate and potentially enhanced sediment supply from ephem- eral washes will further increase aeolian sand transport and dune activity, worsening the present challenges to people living in this region. Connections among climate, vegetation, and aeolian sediment erodibility in this region are highly relevant to other areas of the world with similar environmental problems.

  16. [Spatial change of the grain-size of aeolian sediments in Qira oasis-desert ecotone, Northwest China].

    PubMed

    Lin, Yong Chong; Xu, Li Shuai

    2017-04-18

    In order to understand the environmental influence of oasis-desert ecotone to oasis ecological system, we comparatively analyzed the grain size characteristics of various aeolian sediments, including the sediments in oasis-desert ecotone, shelterbelt and the inside oasis and in Qira River valley. The results showed that the grain size characteristics (including grain-size distribution curve, grain size parameters, and content of different size classes) of sediments in the oasis-desert ecotone were consistent along the prevailing wind direction with a grain-size range of 0.3-200 μm and modal size of 67 μm. All of the sediments were good sorting and mainly composed of suspension components and saltation components, but not denatured saltation and creeping components (>200 μm). They were typically aeolian deposits being short-range transported. The grain sizes of sediments in oasis-desert ecotone were smaller than that in the material sources of Qira River valley and desert (0.3-800 μm), but very similar to those of the modern aeolian deposits in oasis-desert ecotone, shelterbelt and the inside oasis. The denatured saltation and creep components (>200 μm) were suppressed to transport into oasis-desert ecotone because of the high vegetation cover in oasis-desert ecotone. Therefore, like the shelterbelts, the oasis-desert ecotone could also block the invasion of desert. They safeguarded the oasis ecological environment together.

  17. Characterization of alkanes, hopanes, and polycyclic aromatic hydrocarbons (PAHs) in tar-balls collected from the East Coast of Peninsular Malaysia.

    PubMed

    Chandru, Kuhan; Zakaria, Mohamad Pauzi; Anita, Sofia; Shahbazi, Azadeh; Sakari, Mahyar; Bahry, Pourya Shahpoury; Mohamed, Che Abd Rahim

    2008-05-01

    The East Coast of Peninsular Malaysia faces the South China Sea and is vulnerable to oil pollution because of intense petroleum production activities in the area. The South China Sea is also a favored route for supertankers carrying crude oil to the Far East. Consequently, oil spills can occur, causing pollution and contamination in the surrounding areas. Residual oil spills stranded on coastal beaches usually end up as tar-balls. Elucidating the sources of tar-balls using a molecular marker approach is essential in assessing environmental impacts and perhaps settling legal liabilities for affected parties. This study utilizes a multimodal molecular marker approach through the use of diagnostic ratios of alkanes, hopanes, and polycyclic aromatic hydrocarbons (PAHs) to determine the source, distribution and weathering of tar-balls. Hopane ratios (e.g., C29/C30, and summation C31-C35/C30 ratios) were used to identify the sources of tar-balls. The weathering effects were distinguished by using alkanes, namely the unresolved complex mixture (UCM) and low molecular weight/high molecular weight (L/H) ratios. Similarly, PAHs were also used for the determination of weathering processes undergone by the tar-balls. This multimodal molecular marker gave a very strong indication of the sources of tar-balls in this study. For example, 16 out of 17 samples originated from South East Asian Crude Oil (SEACO) with one sample from Merang, Terengganu originating from North Sea Oil (Troll). The TRME-2 sample may have come from a supertanker's ballast water discharge. The second possibility is that the tar-ball may have been transported via oceanographic currents. All 'weathered' sample characterizations were based on the presence of UCM and other ratios. The multimodal molecular marker approach applied in this study has enabled us to partially understand the transport behavior of tar-balls in the marine environment and has revealed insights into the weathering process of tar-balls.

  18. The response of source-bordering aeolian dunefields to sediment-supply changes 2: Controlled floods of the Colorado River in Grand Canyon, Arizona, USA

    USGS Publications Warehouse

    Sankey, Joel B.; Caster, Joshua; Kasprak, Alan; East, Amy

    2018-01-01

    In the Colorado River downstream of Glen Canyon Dam in the Grand Canyon, USA, controlled floods are used to resupply sediment to, and rebuild, river sandbars that have eroded severely over the past five decades owing to dam-induced changes in river flow and sediment supply. In this study, we examine whether controlled floods, can in turn resupply aeolian sediment to some of the large source-bordering aeolian dunefields (SBDs) along the margins of the river. Using a legacy of high-resolution lidar remote-sensing and meteorological data, we characterize the response of four SBDs (a subset of 117 SBDs and other aeolian-sand-dominated areas in the canyon) during four sediment-laden controlled floods of the Colorado River in 2012, 2013, 2014, and 2016. We find that aeolian sediment resupply unambiguously occurred in 8 of the 16 instances of controlled flooding adjacent to SBDs. Resupply attributed to individual floods varied substantially among sites, and occurred with four, three, one, and zero floods at the four sites, respectively. We infer that the relative success of controlled floods as a regulated-river management tool for resupplying sediment to SBDs is analogous to the frequency of resupply observed for fluvial sandbars in this setting, in that sediment resupply was estimated to have occurred for roughly half of the instances of recent controlled flooding at sandbars monitored separately from this study. We find the methods developed in this, and a companion study, are effective tools to quantify geomorphic changes in sediment storage, along linked fluvial and aeolian pathways of sedimentary systems.

  19. The response of source-bordering aeolian dunefields to sediment-supply changes 2: Controlled floods of the Colorado River in Grand Canyon, Arizona, USA

    NASA Astrophysics Data System (ADS)

    Sankey, Joel B.; Caster, Joshua; Kasprak, Alan; East, Amy E.

    2018-06-01

    In the Colorado River downstream of Glen Canyon Dam in the Grand Canyon, USA, controlled floods are used to resupply sediment to, and rebuild, river sandbars that have eroded severely over the past five decades owing to dam-induced changes in river flow and sediment supply. In this study, we examine whether controlled floods, can in turn resupply aeolian sediment to some of the large source-bordering aeolian dunefields (SBDs) along the margins of the river. Using a legacy of high-resolution lidar remote-sensing and meteorological data, we characterize the response of four SBDs (a subset of 117 SBDs and other aeolian-sand-dominated areas in the canyon) during four sediment-laden controlled floods of the Colorado River in 2012, 2013, 2014, and 2016. We find that aeolian sediment resupply unambiguously occurred in 8 of the 16 instances of controlled flooding adjacent to SBDs. Resupply attributed to individual floods varied substantially among sites, and occurred with four, three, one, and zero floods at the four sites, respectively. We infer that the relative success of controlled floods as a regulated-river management tool for resupplying sediment to SBDs is analogous to the frequency of resupply observed for fluvial sandbars in this setting, in that sediment resupply was estimated to have occurred for roughly half of the instances of recent controlled flooding at sandbars monitored separately from this study. We find the methods developed in this, and a companion study, are effective tools to quantify geomorphic changes in sediment storage, along linked fluvial and aeolian pathways of sedimentary systems.

  20. Palaeoclimatic implications of aeolian sediments on the Miaodao Islands, Bohai Sea, East China, based on OSL dating and proxies

    NASA Astrophysics Data System (ADS)

    Xu, Shujian; Ding, Xinchao; Yu, Lupeng; Ni, Zhichao

    2015-12-01

    The loess-paleosol sequences in Shandong Province, East China, is an important aeolian archive, which can provide information for aeolian activity, palaeoclimatic change and sea level change in eastern coast of China since the last interglacial period. However, for so long, most of the studies about loess have been focused on the Chinese Loess Plateau, remaining many questions and disputes about the loess in East China. The Xianjingyuan (XJY) section on the TIA, Bohai Sea, is a representative aeolian section for islands off the eastern coast of China. In this study, optically stimulated luminescence (OSL) dating, particle size and magnetic susceptibility were applied to date and analysis the loess-paleosol sequences in this section. The results show that: (1) The OSL ages at the depths of 0.8 m, 2.5 m, and 3.9 m are 12.6 ± 1.0 ka, 19.2 ± 1.1 ka and 56.9 ± 2.6 ka, respectively, and the loess started to accumulate at ca. 86.5 ka according to the depositional rates (2) The loess accumulated mainly during the Marine Isotope Stage (MIS) 2, i.e., Last glacial maximum and deglaciation, MIS4 and MIS3b with higher depositional rate, coarser grain size, and higher magnetic susceptibility; while paleosol mainly developed during MIS3a, MIS3c and MIS5 with lower depositional rate, finer grain size and lower magnetic susceptibility. (3) The palaeoclimatic changes and aeolian sediments evolution were mainly controlled by the changes of East Asian summer monsoon and sea levels.

  1. Exploring the chemical composition of pelagic tar collected in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Green, H. S.; Reddy, C. M.; Valentine, D. L.; Aeppli, C.; Swarthout, B.; Sharpless, C.; Joyce, P.; Meyer, A. W.; Fuller, S. A.; Gosselin, K.

    2016-12-01

    Pelagic tarballs have been linked to multiple sources and their abundances follow notable historical and geographic trends. An overwhelming number of studies point to operational discharges (cargo washing) as the main source of pelagic tar. In a recent review article, Warnock et al. (2015) summarized that the abundance of tar balls has decreased over the last 30 years. The decreasing trend of tarballs has been attributed to the MARPOL 73/78 Annex I legislation, which was created from conventions held in 1973 and again in 1978 to respond to several tanker accidents and other pollution-related inputs. Two of the studies supporting the "MARPOL 73/78 effect" were based on the historical record of tarballs collected in the North Atlantic Ocean by the Sea Education Association (SEA; Woods Hole, MA). To supplement the SEA record, we performed a series of geochemical analyses on 100 of the SEA samples collected from 1988 to 2014. Bulk and gas chromatographic (GC) analyses revealed that the samples were highly variable. For example, the amount of material that could be dissolved in organic solvent but not measured by gas chromatography (referred to as the % GC amenable, a proxy on the distribution of compound classes that compose the tar) ranged from 10 to 80%, although skewed to values less than 40%. Another parameter, based on the GC data, was the perecentage of the resolved relative to the unresolved signal spanned from 0.1 to 1.8. Nine of the sampes would not dissolve in organic solvents and appear to be soot or coal. This study has an operation limitation as we choose to only examine samples > 1 cm (relative to samples smaller than 1mm). Our approach was based on the assumption that these samples were the most unlikely to be weathered and hence retain the genetic features of the initially released tar. While this study does not have the capacity to test confidently the MARPOL 73/78 effect, it does show that pelagic tars are highly variable, which in turn, have

  2. Membrane curvature and the Tol-Pal complex determine polar localization of the chemoreceptor Tar in E. coli.

    PubMed

    Saaki, Terrens N V; Strahl, Henrik; Hamoen, Leendert W

    2018-02-20

    Chemoreceptors are localized at the cell poles of Escherichia coli and other rod-shaped bacteria. Over the years different mechanisms have been put forward to explain this polar localization; from stochastic clustering, membrane curvature driven localization, interactions with the Tol-Pal complex, to nucleoid exclusion. To evaluate these mechanisms, we monitored the cellular localization of the aspartate chemoreceptor Tar in different deletion mutants. We did not find any indication for either stochastic cluster formation or nucleoid exclusion. However, the presence of a functional Tol-Pal complex appeared to be essential to retain Tar at cell poles. Interestingly, Tar still accumulated at midcell in tol and in pal deletion mutants. In these mutants, the protein appears to gather at the base of division septa, a region characterised by strong membrane curvature. Chemoreceptors, like Tar, form trimer-of-dimers that bend the cell membrane due to a rigid tripod structure. The curvature approaches the curvature of the cell membrane generated during cell division, and localization of chemoreceptor tripods at curved membrane areas is therefore energetically favourable as it lowers membrane tension. Indeed, when we introduced mutations in Tar that abolish the rigid tripod structure, the protein was no longer able to accumulate at midcell or cell poles. These findings favour a model where chemoreceptor localization in E. coli is driven by strong membrane curvature and association with the Tol-Pal complex. Importance Bacteria have exquisite mechanisms to sense and to adapt to the environment they live in. One such mechanism involves the chemotaxis signal transduction pathway, in which chemoreceptors specifically bind certain attracting or repelling molecules and transduce the signals to the cell. In different rod-shaped bacteria, these chemoreceptors localize specifically to cell poles. Here, we examined the polar localization of the aspartate chemoreceptor Tar in E. coli

  3. Class I cultural resource overview for oil shale and tar sands areas in Colorado, Utah and Wyoming.

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

    O'Rourke, D.; Kullen, D.; Gierek, L.

    2007-11-01

    In August 2005, the U.S. Congress enacted the Energy Policy Act of 2005, Public Law 109-58. In Section 369 of this Act, also known as the 'Oil Shale, Tar Sands, and Other Strategic Unconventional Fuels Act of 2005', Congress declared that oil shale and tar sands (and other unconventional fuels) are strategically important domestic energy resources that should be developed to reduce the nation's growing dependence on oil from politically and economically unstable foreign sources. The Bureau of Land Management (BLM) is developing a Programmatic Environmental Impact Statement (PEIS) to evaluate alternatives for establishing commercial oil shale and tar sandsmore » leasing programs in Colorado, Wyoming, and Utah. This PEIS evaluates the potential impacts of alternatives identifying BLM-administered lands as available for application for commercial leasing of oil shale resources within the three states and of tar sands resources within Utah. The scope of the analysis of the PEIS also includes an assessment of the potential effects of future commercial leasing. This Class I cultural resources study is in support of the Draft Oil Shale and Tar Sands Resource Management Plan Amendments to Address Land Use Allocations in Colorado, Utah, and Wyoming and Programmatic Environmental Impact Statement and is an attempt to synthesize archaeological data covering the most geologically prospective lands for oil shale and tar sands in Colorado, Utah, and Wyoming. This report is based solely on geographic information system (GIS) data held by the Colorado, Utah, and Wyoming State Historic Preservation Offices (SHPOs). The GIS data include the information that the BLM has provided to the SHPOs. The primary purpose of the Class I cultural resources overview is to provide information on the affected environment for the PEIS. Furthermore, this report provides recommendations to support planning decisions and the management of cultural resources that could be impacted by future oil shale

  4. Tar-free fuel gas production from high temperature pyrolysis of sewage sludge

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

    Zhang, Leguan; Xiao, Bo; Hu, Zhiquan

    2014-01-15

    Highlights: • High temperature pyrolysis of sewage sludge was efficient for producing tar-free fuel gas. • Complete tar removal and volatile matter release were at elevated temperature of 1300 °C. • Sewage sludge was converted to residual solid with high ash content. • 72.60% of energy conversion efficiency for gas production in high temperature pyrolysis. • Investment and costing for tar cleaning were reduced. - Abstract: Pyrolysis of sewage sludge was studied in a free-fall reactor at 1000–1400 °C. The results showed that the volatile matter in the sludge could be completely released to gaseous product at 1300 °C. Themore » high temperature was in favor of H{sub 2} and CO in the produced gas. However, the low heating value (LHV) of the gas decreased from 15.68 MJ/N m{sup 3} to 9.10 MJ/N m{sup 3} with temperature increasing from 1000 °C to 1400 °C. The obtained residual solid was characterized by high ash content. The energy balance indicated that the most heating value in the sludge was in the gaseous product.« less

  5. Brown carbon in tar balls from smoldering biomass combustion

    Treesearch

    R. K. Chakrabarty; H. Moosmuller; L.-W. A. Chen; K. Lewis; W. P. Arnott; C. Mazzoleni; M. K. Dubey; C. E. Wold; W. M. Hao; S. M. Kreidenweis

    2010-01-01

    We report the direct observation of laboratory production of spherical, carbonaceous particles - "tar balls" - from smoldering combustion of two commonly occurring dry mid-latitude fuels. Real-time measurements of spectrally varying absorption Angstrom coefficients (AAC) indicate that a class of light absorbing organic carbon (OC) with wavelength dependent...

  6. Biomechanical comparison of a novel engine-driven ridge spreader and conventional ridge splitting techniques.

    PubMed

    Jung, Gyu-Un; Kim, Jun Hwan; Lim, Nam Hun; Yoon, Gil Ho; Han, Ji-Young

    2017-06-01

    Ridge splitting techniques are used for horizontal ridge augmentation in implant dentistry. Recently, a novel engine-driven ridge splitting technique was introduced. This study compared the mechanical forces produced by conventional and engine-driven ridge splitting techniques in porcine mandibles. In 33 pigs, mandibular premolar areas were selected for the ridge splitting procedures, designed as a randomized split-mouth study. The conventional group underwent a chisel-and-mallet procedure (control group, n = 20), and percussive impulse (Newton second, Ns) was measured using a sensor attached to the mallet. In the engine-driven ridge spreader group (test group, n = 23), a load cell was used to measure torque values (Newton centimeter, Ncm). Horizontal acceleration generated during procedures (control group, n = 10 and test group, n = 10) was compared between the groups. After ridge splitting, the alveolar crest width was significantly increased both in the control (1.23 ± 0.45 mm) and test (0.98 ± 0.41 mm) groups with no significant differences between the groups. The average impulse of the control group was 4.74 ± 1.05 Ns. Torque generated by rotation in the test group was 9.07 ± 2.15 Ncm. Horizontal acceleration was significantly less in the test group (0.82 ± 1.05 g) than the control group (64.07 ± 42.62 g) (P < 0.001). Narrow edentulous ridges can be expanded by novel engine-driven ridge spreaders. Within the limits of this study, the results suggested that an engine-driven ridge splitting technique may be less traumatic and less invasive than a conventional ridge splitting technique. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. Radiocarbon dating of extinct fauna in the Americas recovered from tar pits

    NASA Astrophysics Data System (ADS)

    Jull, A. J. T.; Iturralde-Vinent, M.; O'Malley, J. M.; MacPhee, R. D. E.; McDonald, H. G.; Martin, P. S.; Moody, J.; Rincón, A.

    2004-08-01

    We have obtained radiocarbon dates by accelerator mass spectrometry on bones of extinct large mammals from tar pits. Results on some samples of Glyptodon and Holmesina (extinct large mammals similar to armadillos) yielded ages of >25 and >21 ka, respectively. We also studied the radiocarbon ages of three different samples of bones from the extinct Cuban ground sloth, Parocnus bownii, which yielded dates ranging from 4960 ± 280 to 11 880 ± 420 yr BP. In order to remove the tar component pretreat the samples sufficiently to obtain reliable dates, we cleaned the samples by Soxhlet extraction in benzene. Resulting samples of collagenous material were often small.

  8. Downslope coarsening in aeolian grainflows of the Navajo Sandstone

    NASA Astrophysics Data System (ADS)

    Loope, David B.; Elder, James F.; Sweeney, Mark R.

    2012-07-01

    Downslope coarsening in grainflows has been observed on present-day dunes and generated in labs, but few previous studies have examined vertical sorting in ancient aeolian grainflows. We studied the grainflow strata of the Jurassic Navajo Sandstone in the southern Utah portion of its outcrop belt from Zion National Park (west) to Coyote Buttes and The Dive (east). At each study site, thick sets of grainflow-dominated cross-strata that were deposited by large transverse dunes comprise the bulk of the Navajo Sandstone. We studied three stratigraphic columns, one per site, composed almost exclusively of aeolian cross-strata. For each column, samples were obtained from one grainflow stratum in each consecutive set of the column, for a total of 139 samples from thirty-two sets of cross-strata. To investigate grading perpendicular to bedding within individual grainflows, we collected fourteen samples from four superimposed grainflow strata at The Dive. Samples were analyzed with a Malvern Mastersizer 2000 laser diffraction particle analyser. The median grain size of grainflow samples ranges from fine sand (164 μm) to coarse sand (617 μm). Using Folk and Ward criteria, samples are well-sorted to moderately-well-sorted. All but one of the twenty-eight sets showed at least slight downslope coarsening, but in general, downslope coarsening was not as well-developed or as consistent as that reported in laboratory subaqueous grainflows. Because coarse sand should be quickly sequestered within preserved cross-strata when bedforms climb, grain-size studies may help to test hypotheses for the stacking of sets of cross-strata.

  9. Controlling and assessing pressure conditions during treatment of tar sands formations

    DOEpatents

    Zhang, Etuan; Beer, Gary Lee

    2015-11-10

    A method for treating a tar sands formation includes providing heat to at least part of a hydrocarbon layer in the tar sands formation from a plurality of heaters located in the formation. Heat is allowed to transfer from the heaters to at least a portion of the formation. A pressure in the portion of the formation is controlled such that the pressure remains below a fracture pressure of the formation overburden while allowing the portion of the formation to heat to a selected average temperature of at least about 280.degree. C. and at most about 300.degree. C. The pressure in the portion of the formation is reduced to a selected pressure after the portion of the formation reaches the selected average temperature.

  10. Polygonal Ridge Networks on Mars

    NASA Astrophysics Data System (ADS)

    Kerber, Laura; Dickson, James; Grosfils, Eric; Head, James W.

    2016-10-01

    Polygonal ridge networks, also known as boxwork or reticulate ridges, are found in numerous locations and geological contexts across Mars. While networks formed from mineralized fractures hint at hot, possibly life-sustaining circulating ground waters, networks formed by impact-driven clasting diking, magmatic dikes, gas escape, or lava flows do not have the same astrobiological implications. Distinguishing the morphologies and geological context of the ridge networks sheds light on their potential as astrobiological and mineral resource sites of interest. The most widespread type of ridge morphology is characteristic of the Nili Fossae and Nilosyrtis region and consists of thin, criss-crossing ridges with a variety of heights, widths, and intersection angles. They are found in ancient Noachian terrains at a variety of altitudes and geographic locations and may be a mixture of clastic dikes, brecciated dikes, and mineral veins. They occur in the same general areas as valley networks and ancient lake basins, but they are not more numerous where these features are concentrated, and can appear in places where they morphologies are absent. Similarly, some of the ridge networks are associated with hydrated mineral detections, but some occur in locations without detections. Smaller, light-toned ridges of variable widths have been found in Gale Crater and other rover sites and are interpreted to be smaller version of the Nili-like ridges, in this case formed by the mineralization of fractures. This type of ridge is likely to be found in many other places on Mars as more high-resolution data becomes available. Hellas Basin is host to a third type of ridge morphology consisting of large, thick, light-toned ridges forming regular polygons at several superimposed scales. While still enigmatic, these are most likely to be the result of sediment-filled fractures. The Eastern Medusae Fossae Formation contains large swaths of a fourth, previously undocumented, ridge network type

  11. Deformation of Forearcs during Aseismic Ridge Subduction

    NASA Astrophysics Data System (ADS)

    Zeumann, S.; Hampel, A.

    2014-12-01

    Subduction of aseismic oceanic ridges causes considerable deformation of the forearc region. To identify the crucial parameters for forearc deformation we created 3D finite-element models representing both erosive and accretive forearcs as well as migrating and non-migrating ridges. As natural examples we choose the Cocos ridge subducting stationary beneath the erosive margin of Costa Rica and the Nazca and Gagua Ridges that migrate along the erosive Peruvian margin and the accretive accretive Ryukyu margin, respectively. A series of models show that the deformation of the forearc depends on the ridge shape (height, width), on the frictional coupling along the plate interface and the mechanical strength of the forearc. The forearc is uplifted and moved sideward during ridge subduction. Strain components show domains of both, shortening and extension. Along the ridge axis, extension occurs except at the ridge tip, where shortening prevails. The strain component normal to the ridge axis reveals extension at the ridge tip and contraction above the ridge flanks. Shortening and extension increase with increasing ridge height. Higher friction coefficients lead to less extension and more shortening. Accretive wedges show larger indentation at the model trench. For stationary ridges (Cocos Ridge) the deformation pattern of the forearc is symmetric with respect to the ridge axis whereas for migrating ridges (Nazca Ridge, Gagua Ridge) the oblique convergence direction leads to asymmetric deformation of the forearc. In case of ridge migration, uplift occurs at the leading flank of the ridge and subsidence at the trailing flank, in agreement with field observations and analogue models. For a model with a 200-km-wide and 1500-m-high ridge (i.e. similar to the dimensions of the Nazca Ridge), the modelled uplift rate at the southern ridge flank of the ridge is ~1 mm/a, which agrees well with uplift rates of ~0.7 mm/a derived from the elevation of marine terraces in southern Peru.

  12. Characteristics of PAH tar oil contaminated soils-Black particles, resins and implications for treatment strategies.

    PubMed

    Trellu, Clément; Miltner, Anja; Gallo, Rosita; Huguenot, David; van Hullebusch, Eric D; Esposito, Giovanni; Oturan, Mehmet A; Kästner, Matthias

    2017-04-05

    Tar oil contamination is a major environmental concern due to health impacts of polycyclic aromatic hydrocarbons (PAH) and the difficulty of reaching acceptable remediation end-points. Six tar oil-contaminated soils with different industrial histories were compared to investigate contamination characteristics by black particles. Here we provide a simple method tested on 6 soils to visualize and identify large amounts of black particles (BP) as either solid aggregates of resinified and weathered tar oil or various wood/coke/coal-like materials derived from the contamination history. These materials contain 2-10 times higher PAH concentrations than the average soil and were dominantly found in the sand fraction containing 42-86% of the total PAH. The PAH contamination in the different granulometric fractions was directly proportional to the respective total organic carbon content, since the PAH were associated to the carbonaceous particulate materials. Significantly lower (bio)availability of PAH associated to these carbonaceous phases is widely recognized, thus limiting the efficiency of remediation techniques. We provide a conceptual model of the limited mass transfer of PAH from resinated tar oil phases to the water phase and emphasize the options to physically separate BP based on their lower bulk density and slower settling velocity. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Aspects of tar sands development in Nigeria

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

    Adewusi, V.A.

    1992-07-01

    Development of Nigerian massive reserves of crude bitumen and associated heavy oil is imminent in view of the impacts that the huge importation of these materials and their products have on the nation's economy, coupled with the depleting reserves of Nigeria and highlights the appropriate production technology options and their environmental implications. The utilization potentials of these resources are also enumerated, as well as the government's role in achieving accelerated, long-term tar sands development in the country.

  14. PROPAGATION AND LINKAGE OF OCEANIC RIDGE SEGMENTS.

    USGS Publications Warehouse

    Pollard, David D.; Aydin, Atilla

    1984-01-01

    An investigation was made of spreading ridges and the development of structures that link ridge segments using an analogy between ridges and cracks in elastic plates. The ridge-propagation force and a path factor that controls propagation direction were calculated for echelon ridge segments propagating toward each other. The ridge-propagation force increases as ridge ends approach but then declines sharply as the ends pass, so ridge segments may overlap somewhat. The sign of the path factor changes as ridge ends approach and pass, so the overlapping ridge ends may diverge and then converge following a hook-shaped path. The magnitudes of shear stresses in the plane of the plate and orientations of maximum shear planes between adjacent ridge segments were calculated to study transform faulting. For different loading conditions simulating ridge push, plate pull, and ridge suction, a zone of intense mechanical interaction between adjacent ridge ends in which stresses are concentrated was identified. The magnitudes of mean stresses in the plane of the plate and orientations of principal stress planes were also calculated.

  15. Remediation of Coal Tar by STAR: Self-Sustaining Propagation Across Clean Gaps

    NASA Astrophysics Data System (ADS)

    Gerhard, J.; Brown, J.; Torero, J. L.; Grant, G.

    2016-12-01

    Self-sustaining Treatment for Active Remediation (STAR) is an emerging remediation technique which utilizes a subsurface smouldering reaction to destroy non-aqueous phase liquids (NAPL) in situ. The reaction is self-sustaining in that, once ignited, the destructive smouldering front will propagate outwards using only the energy embedded in the contaminant. However, it is known that coal tar can occur as both a continuous pool as well as in distinct seams separated by clean intervals. This study evaluated the hypothesis that the smouldering reaction can cross or `jump' clean gaps by transferring enough heat through the gap to re-ignite the reaction in the contaminated region beyond. Column and 2D box experiments were performed at two scales to determine the maximum clean gap which could be jumped vertically and horizontally. Once the maximum gap had been determined, sensitivity to various in situ and engineering control parameters were explored including: coal tar layer thickness, soil permeability, moisture content, NAPL saturation, and air injection flowrate. High resolution thermocouples informed the progress of the reaction, continuous gas emissions analysis revealed when the reaction was active and dormant, and detailed excavation mapped the extent of remediation and whether gaps were successfully jumped. The work demonstrated that substantial clean gaps, approaching the limit of the laboratory scale, can be jumped by the smouldering reaction using convective heat transfer. Also observed in some cases was the mobilization of pre-heated coal tar into the clean gaps and the reaction's ability to propagate through and destroy coal tar both adjacent to and within the gaps. This work is providing new insights into the robust nature of the technology for in situ applications, and indicating how extreme the heterogeneity has to be before the reaction is interrupted and a new ignition location would be required.

  16. Coal-Tar-Based Pavement Sealcoat and PAHs: Implications for the Environment, Human Health, and Stormwater Management

    PubMed Central

    2012-01-01

    Coal-tar-based sealcoat products, widely used in the central and eastern U.S. on parking lots, driveways, and even playgrounds, are typically 20−35% coal-tar pitch, a known human carcinogen that contains about 200 polycyclic aromatic hydrocarbon (PAH) compounds. Research continues to identify environmental compartments—including stormwater runoff, lake sediment, soil, house dust, and most recently, air—contaminated by PAHs from coal-tar-based sealcoat and to demonstrate potential risks to biological communities and human health. In many cases, the levels of contamination associated with sealed pavement are striking relative to levels near unsealed pavement: PAH concentrations in air over pavement with freshly applied coal-tar-based sealcoat, for example, were hundreds to thousands of times higher than those in air over unsealed pavement. Even a small amount of sealcoated pavement can be the dominant source of PAHs to sediment in stormwater-retention ponds; proper disposal of such PAH-contaminated sediment can be extremely costly. Several local governments, the District of Columbia, and the State of Washington have banned use of these products, and several national and regional hardware and home-improvement retailers have voluntarily ceased selling them. PMID:22296333

  17. Coal-tar-based pavement sealcoat and PAHs: implications for the environment, human health, and stormwater management

    USGS Publications Warehouse

    Mahler, Barbara J.; Van Metre, Peter C.; Crane, Judy L.; Watts, Alison W.; Scoggins, Mateo; Williams, E. Spencer

    2012-01-01

    Coal-tar-based sealcoat products, widely used in the central and eastern U.S. on parking lots, driveways, and even playgrounds, are typically 20-35% coal-tar pitch, a known human carcinogen that contains about 200 polycyclic aromatic hydrocarbon (PAH) compounds. Research continues to identify environmental compartments—including stormwater runoff, lake sediment, soil, house dust, and most recently, air—contaminated by PAHs from coal-tar-based sealcoat and to demonstrate potential risks to biological communities and human health. In many cases, the levels of contamination associated with sealed pavement are striking relative to levels near unsealed pavement: PAH concentrations in air over pavement with freshly applied coal-tar-based sealcoat, for example, were hundreds to thousands of times higher than those in air over unsealed pavement. Even a small amount of sealcoated pavement can be the dominant source of PAHs to sediment in stormwater-retention ponds; proper disposal of such PAH-contaminated sediment can be extremely costly. Several local governments, the District of Columbia, and the State of Washington have banned use of these products, and several national and regional hardware and home-improvement retailers have voluntarily ceased selling them.

  18. Coal-tar-based pavement sealcoat and PAHs: implications for the environment, human health, and stormwater management.

    PubMed

    Mahler, Barbara J; Metre, Peter C Van; Crane, Judy L; Watts, Alison W; Scoggins, Mateo; Williams, E Spencer

    2012-03-20

    Coal-tar-based sealcoat products, widely used in the central and eastern U.S. on parking lots, driveways, and even playgrounds, are typically 20-35% coal-tar pitch, a known human carcinogen that contains about 200 polycyclic aromatic hydrocarbon (PAH) compounds. Research continues to identify environmental compartments-including stormwater runoff, lake sediment, soil, house dust, and most recently, air-contaminated by PAHs from coal-tar-based sealcoat and to demonstrate potential risks to biological communities and human health. In many cases, the levels of contamination associated with sealed pavement are striking relative to levels near unsealed pavement: PAH concentrations in air over pavement with freshly applied coal-tar-based sealcoat, for example, were hundreds to thousands of times higher than those in air over unsealed pavement. Even a small amount of sealcoated pavement can be the dominant source of PAHs to sediment in stormwater-retention ponds; proper disposal of such PAH-contaminated sediment can be extremely costly. Several local governments, the District of Columbia, and the State of Washington have banned use of these products, and several national and regional hardware and home-improvement retailers have voluntarily ceased selling them.

  19. Tar Creek study, Sargent oil field, Santa Clara County, California

    USGS Publications Warehouse

    Wagner, David L.; Fedasko, Bill; Carnahan, J.R.; Brunetti, Ross; Magoon, Leslie B.; Lillis, Paul G.; Lorenson, T.D.; Stanley, Richard G.

    2002-01-01

    Field work in the Tar Creek area of Sargent oil field was performed June 26 to 28, 2000. The Santa Clara County study area is located in Sections, 30, 31, and 32, Township 11 South, Range 4 East, M.D.B&M; and in Sections 25 and 36, Township 11 South, Range 3 East, M.D.B.&M., north and south of Tar Creek, west of Highway 101. The work was a cooperative effort of the California Department of Conservation's Division of Oil, Gas, and Geothermal Resources (DOGGR), California Geological Survey (CGS), and the United States Geological Survey (USGS). The purpose of the project was to map the stratigraphy and geologic structure (David Wagner, CGS); sample oil for age dating (Les Magoon, USGS); and search for undocumented wells plus conduct a GPS survey of the area (Bill Fedasko, J.P. Carnahan, and Ross Brunetti, DOGGR)

  20. Coal-tar pavement sealants might substantially increase children's PAH exposures

    USGS Publications Warehouse

    Williams, E. Spencer; Mahler, Barbara J.; Van Metre, Peter C.

    2012-01-01

    Dietary ingestion has been identified repeatedly as the primary route of human exposure to polycyclic aromatic hydrocarbons (PAHs), seven of which are classified as probable human carcinogens (B2 PAHs) by the U.S. EPA. Humans are exposed to PAHs through ingestion of cooked and uncooked foods, incidental ingestion of soil and dust, inhalation of ambient air, and absorption through skin. Although PAH sources are ubiquitous in the environment, one recently identified PAH source stands out: Coal-tar-based pavement sealant—a product applied to many parking lots, driveways, and even playgrounds primarily in the central, southern, and eastern U.S.—has PAH concentrations 100–1000 times greater than most other PAH sources. It was reported recently that PAH concentrations in house dust in residences adjacent to parking lots with coal-tar-based sealant were 25 times higher than in residences adjacent to unsealed asphalt parking lots.

  1. Citizen science identifies the effects of nitrogen dioxide and other environmental drivers on tar spot of sycamore.

    PubMed

    Gosling, Laura; Ashmore, Mike; Sparks, Tim; Bell, Nigel

    2016-07-01

    Elevated sulphur dioxide (SO2) concentrations were the major cause of the absence of symptoms of tar spot (Rhytisma acerinum) of sycamore (Acer pseudoplatanus), in urban areas in the 1970s. The subsequent large decline in SO2 concentrations has not always been accompanied by increased tar spot symptoms, for reasons that have remained unresolved. We used a large citizen science survey, providing over 1000 records across England, to test two competing hypotheses proposed in earlier studies. We were able to demonstrate the validity of both hypotheses; tar spot symptoms were reduced where there were fewer fallen leaves as a source of inoculum, and elevated nitrogen dioxide concentrations reduced tar spot symptoms above a threshold concentration of about 20 μg m(-3). Symptom severity was also lower at sites with higher temperature and lower rainfall. Our findings demonstrate the power of citizen science to resolve competing hypotheses about the impacts of air pollution and other environmental drivers. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  2. Effect of cavitation on the properties of coal-tar pitch as studied by gas-liquid chromatography

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

    M.I. Baikenov; T.B. Omarbekov; S.K. Amerkhanova

    2008-02-15

    The applicability of the cavitation-wave effect to coal-tar pitch processing is considered. The results of the GLC analysis of the test material before and after rotor-pulsation cavitation treatment are given. The organic matter of coal-tar pitch was found to degrade upon cavitation; as a result of this, the yields of light and medium fractions considerably increased. 5 refs., 2 figs., 4 tabs.

  3. The National Wind Erosion Research Network: Building a standardized long-term data resource for aeolian research, modeling and land management

    USGS Publications Warehouse

    Webb, Nicholas P.; Herrick, Jeffrey E.; Van Zee, Justin W; Courtright, Ericha M; Hugenholtz, Ted M; Zobeck, Ted M; Okin, Gregory S.; Barchyn, Thomas E; Billings, Benjamin J; Boyd, Robert A.; Clingan, Scott D; Cooper, Brad F; Duniway, Michael C.; Derner, Justin D.; Fox, Fred A; Havstad, Kris M.; Heilman, Philip; LaPlante, Valerie; Ludwig, Noel A; Metz, Loretta J; Nearing, Mark A; Norfleet, M Lee; Pierson, Frederick B; Sanderson, Matt A; Sharrat, Brenton S; Steiner, Jean L; Tatarko, John; Tedela, Negussie H; Todelo, David; Unnasch, Robert S; Van Pelt, R Scott; Wagner, Larry

    2016-01-01

    The National Wind Erosion Research Network was established in 2014 as a collaborative effort led by the United States Department of Agriculture’s Agricultural Research Service and Natural Resources Conservation Service, and the United States Department of the Interior’s Bureau of Land Management, to address the need for a long-term research program to meet critical challenges in wind erosion research and management in the United States. The Network has three aims: (1) provide data to support understanding of basic aeolian processes across land use types, land cover types, and management practices, (2) support development and application of models to assess wind erosion and dust emission and their impacts on human and environmental systems, and (3) encourage collaboration among the aeolian research community and resource managers for the transfer of wind erosion technologies. The Network currently consists of thirteen intensively instrumented sites providing measurements of aeolian sediment transport rates, meteorological conditions, and soil and vegetation properties that influence wind erosion. Network sites are located across rangelands, croplands, and deserts of the western US. In support of Network activities, http://winderosionnetwork.org was developed as a portal for information about the Network, providing site descriptions, measurement protocols, and data visualization tools to facilitate collaboration with scientists and managers interested in the Network and accessing Network products. The Network provides a mechanism for engaging national and international partners in a wind erosion research program that addresses the need for improved understanding and prediction of aeolian processes across complex and diverse land use types and management practices.

  4. Microbial Diversity in Natural Asphalts of the Rancho La Brea Tar Pits▿

    PubMed Central

    Kim, Jong-Shik; Crowley, David E.

    2007-01-01

    Bacteria commonly inhabit subsurface oil reservoirs, but almost nothing is known yet about microorganisms that live in naturally occurring terrestrial oil seeps and natural asphalts that are comprised of highly recalcitrant petroleum hydrocarbons. Here we report the first survey of microbial diversity in ca. 28,000-year-old samples of natural asphalts from the Rancho La Brea Tar Pits in Los Angeles, CA. Microbiological studies included analyses of 16S rRNA gene sequences and DNA encoding aromatic ring-hydroxylating dioxygenases from two tar pits differing in chemical composition. Our results revealed a wide range of phylogenetic groups within the Archaea and Bacteria domains, in which individual taxonomic clusters were comprised of sets of closely related species within novel genera and families. Fluorescent staining of asphalt-soil particles using phylogenetic probes for Archaea, Bacteria, and Pseudomonas showed coexistence of mixed microbial communities at high cell densities. Genes encoding dioxygenases included three novel clusters of enzymes. The discovery of life in the tar pits provides an avenue for further studies of the evolution of enzymes and catabolic pathways for bacteria that have been exposed to complex hydrocarbons for millennia. These bacteria also should have application for industrial microbiology and bioremediation. PMID:17416692

  5. Fine-Branched Ridges

    NASA Image and Video Library

    2015-10-14

    This image from NASA Mars Reconnaissance Orbiter spacecraft shows numerous branching ridges with various degrees of sinuosity. These branching forms resemble tributaries funneling and draining into larger channel trunks towards the upper portion of the scene. The raised relief of these branching ridges suggests that these are ancient channels are inverted due to lithification and cementation of the riverbed sediment, which made it more resistant to erosion than the surrounding material. Wind-blown bedforms are abundant and resemble small ridges that are aligned in an approximately north-south direction. http://photojournal.jpl.nasa.gov/catalog/PIA20006

  6. Fingermark ridge drift.

    PubMed

    De Alcaraz-Fossoul, Josep; Roberts, Katherine A; Feixat, Carme Barrot; Hogrebe, Gregory G; Badia, Manel Gené

    2016-01-01

    Distortions of the fingermark topography are usually considered when comparing latent and exemplar fingerprints. These alterations are characterized as caused by an extrinsic action, which affects entire areas of the deposition and alters the overall flow of a series of contiguous ridges. Here we introduce a novel visual phenomenon that does not follow these principles, named fingermark ridge drift. An experiment was designed that included variables such as type of secretion (eccrine and sebaceous), substrate (glass and polystyrene), and degrees of exposure to natural light (darkness, shade, and direct light) indoors. Fingermarks were sequentially visualized with titanium dioxide powder, photographed and analyzed. The comparison between fresh and aged depositions revealed that under certain environmental conditions an individual ridge could randomly change its original position regardless of its unaltered adjacent ridges. The causes of the drift phenomenon are not well understood. We believe it is exclusively associated with intrinsic natural aging processes of latent fingermarks. This discovery will help explain the detection of certain dissimilarities at the minutiae/ridge level; determine more accurate "hits"; identify potentially erroneous corresponding points; and rethink identification protocols, especially the criteria of "no single minutiae discrepancy" for a positive identification. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  7. Contextual view of Point Bonita Ridge, showing Bonita Ridge access ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Contextual view of Point Bonita Ridge, showing Bonita Ridge access road retaining wall and location of Signal Corps Radar (S.C.R.) 296 Station 5 Transmitter Building foundation (see stake at center left), camera facing north - Fort Barry, Signal Corps Radar 296, Station 5, Transmitter Building Foundation, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

  8. Effects of varying marijuana potency on deposition of tar and delta9-THC in the lung during smoking.

    PubMed

    Matthias, P; Tashkin, D P; Marques-Magallanes, J A; Wilkins, J N; Simmons, M S

    1997-12-01

    To determine whether smoking more, compared to less, potent marijuana (MJ) cigarettes to a desired level of intoxication ("high") reduces pulmonary exposure to noxious smoke components, in 10 habitual smokers of MJ, we measured respiratory delivery and deposition of tar and delta9-tetrahydrocannabinol (THC), carboxyhemoglobin (COHb) boost, smoking topography, including cumulative puff volume (CPV) and breathholding time, change in heart rate (deltaHR) and "high" during ad lib smoking of 0, 1.77, and 3.95% MJ cigarettes on 3 separate days. At each session, subjects had access to only a single MJ cigarette. On average, smoking topography and COHb boost did not differ across the different strengths of MJ, while THC delivery, as well as HR, were significantly greater (p < 0.01) and tar deposition significantly less (p < 0.03) for 3.95% than 1.77% MJ. Although individual adaptations in smoking topography for 3.95% compared to 1.77% MJ were highly variable, three subjects with the lowest 3.95% MJ:1.77% MJ ratios for CPV also displayed the lowest 3.95% MJ:1.77% MJ ratios for tar deposition. In vitro studies using a standardized smoking technique revealed a mean 25% lower tar yield from 3.95% than 1.77% MJ (p < 0.05), but no difference between 1.77% and 0% marijuana. Under the conditions of this study, we conclude that tar delivery is reduced relative to THC content in a minority of subjects, and this reduction appears to be due to a reduced intake of smoke (decreased CPV) and/or a reduced tar yield from the stronger MJ preparation.

  9. Ancient Martian aeolian processes and palaeomorphology reconstructed from the Stimson formation on the lower slope of Aeolis Mons, Gale crater, Mars

    USGS Publications Warehouse

    Banham, Steve G.; Gupta, Sanjeev; Rubin, David M.; Watkins, Jessica A.; Sumner, Dawn Y.; Edgett, Kenneth S.; Grotzinger, John P.; Lewis, Kevin W.; Edgar, Lauren; Stack, Kathryn M.; Barnes, Robert; Bell, Jame F. III; Day, Mackenzie D.; Ewing, Ryan C.; Lapotre, Mathieu G.A.; Stein, Nathan T.; Rivera-Hernandez, Frances; Vasavada, Ashwin R.

    2018-01-01

    Reconstruction of the palaeoenvironmental context of Martian sedimentary rocks is central to studies of ancient Martian habitability and regional palaeoclimate history. This paper reports the analysis of a distinct aeolian deposit preserved in Gale crater, Mars, and evaluates its palaeomorphology, the processes responsible for its deposition, and its implications for Gale crater geological history and regional palaeoclimate. Whilst exploring the sedimentary succession cropping out on the northern flank of Aeolis Mons, Gale crater, the Mars Science Laboratory rover Curiosity encountered a decametre‐thick sandstone succession, named the Stimson formation, unconformably overlying lacustrine deposits of the Murray formation. The sandstone contains sand grains characterized by high roundness and sphericity, and cross‐bedding on the order of 1 m in thickness, separated by sub‐horizontal bounding surfaces traceable for tens of metres across outcrops. The cross‐beds are composed of uniform thickness cross‐laminations interpreted as wind‐ripple strata. Cross‐sets are separated by sub‐horizontal bounding surfaces traceable for tens of metres across outcrops that are interpreted as dune migration surfaces. Grain characteristics and presence of wind‐ripple strata indicate deposition of the Stimson formation by aeolian processes. The absence of features characteristic of damp or wet aeolian sediment accumulation indicate deposition in a dry aeolian system. Reconstruction of the palaeogeomorphology suggests that the Stimson dune field was composed largely of simple sinuous crescentic dunes with a height of ca10 m, and wavelengths of ca 150 m, with local development of complex dunes. Analysis of cross‐strata dip‐azimuths indicates that the general dune migration direction and hence net sediment transport was towards the north‐east. The juxtaposition of a dry aeolian system unconformably above the lacustrine Murray formation represents starkly

  10. PAHs underfoot: Contaminated dust from coal-tar sealcoated pavement is widespread in the United States

    USGS Publications Warehouse

    Van Metre, P.C.; Mahler, B.J.; Wilson, J.T.

    2009-01-01

    We reported in 2005 that runoff from parking lots treated with coal-tar-based sealcoat was a major source of polycyclic aromatic hydrocarbons (PAHs) to streams in Austin, Texas. Here we present new data from nine U. S. cities that show nationwide patterns in concentrations of PAHs associated with sealcoat Dust was swept from parking lots in six cities in the central and eastern U. S., where coal-tar-based sealcoat dominates use, and three cities in the western U. S., where asphalt-based sealcoat dominates use. For six central and eastern cities, median ?? PAH concentrations in dust from sealcoated and unsealcoated pavement are 2200 and 27 mg/kg, respectively. For three western cities, median ?? PAH concentrations in dust from sealcoated and unsealcoated pavement are similar and very low (2. 1 and 0. 8 mg/kg, respectively). Lakes in the central and eastern cities where pavement was sampled have bottom sediments with higher PAH concentrations than do those in the western cities relative to degree of urbanization. Bottom-sediment PAH assemblages are similar to those of sealcoated pavement dust regionally, implicating coal-tar-based sealcoat as a PAH source to the central and eastern lakes. Concentrations of benzo[a]pyrene in dust from coal-tar sealcoated pavement and adjacent soils greatly exceed generic soil screening levels, suggesting that research on human-health risk is warranted.

  11. Uptake of pyrene in a breast-fed child of a mother treated with coal tar.

    PubMed

    Scheepers, Paul T J; van Houtum, Jeanette L M; Anzion, Rob B M; Harder, Rianne; Bos, Rob P; van der Valk, Pieter G M

    2009-01-01

    A woman was treated for atopic dermatitis with coal tar containing ointments. Coal tar containing ointments contain genotoxic polycyclic aromatic hydrocarbons. Over a period of 50 days the accumulated dose of different coal tar containing ointments treatments corresponded to 993 mg of pyrene and 464 mg of benz[a]pyrene. During this treatment she gave breast milk to her 3-month-old daughter. Analysis of urine samples from the breast-fed child showed elevated levels of urinary excretion of a metabolite of pyrene (1-hydroxypyrene, 1-OHP). These levels were in the same range as urinary excretion levels of this metabolite observed in the mother's urine. As no pyrene was observed in breast milk at a limit of determination of 0.0035 micromol/L, transfer of pyrene from mother to child via breast milk is not likely. Also, a low level of 1-hydroxypyrene observed in the mother's milk did not account for the observed urinary excretion levels in the child. It must therefore be assumed that pyrene was transferred from mother to child via another route, presumably direct skin-to-skin or skin-to-mouth contact. Dermatologists should inform their patients who receive treatment with coal tar containing ointments of the risk of transfer of polycyclic aromatic hydrocarbons by skin-to-skin or skin-to-mouth contact.

  12. Changing characteristics of arctic pressure ridges

    NASA Astrophysics Data System (ADS)

    Wadhams, Peter; Toberg, Nick

    2012-04-01

    The advent of multibeam sonar permits us to obtain full three-dimensional maps of the underside of sea ice. In particular this enables us to distinguish the morphological characteristics of first-year (FY) and multi-year (MY) pressure ridges in a statistically valid way, whereas in the past only a small number of ridges could be mapped laboriously by drilling. In this study pressure ridge distributions from two parts of the Arctic Ocean are compared, in both the cases using mainly data collected by the submarine “Tireless” in March 2007 during two specific grid surveys, in the Beaufort Sea at about 75° N, 140° W (N of Prudhoe Bay), and north of Ellesmere Island at about 83° 20‧ N, 64° W. In the Beaufort Sea the ice was mainly FY, and later melted or broke up as this area became ice-free during the subsequent summer. N of Ellesmere Island the ice was mainly MY. Ridge depth and spacing distributions were derived for each region using the boat's upward looking sonar, combined with distributions of shapes of the ridges encountered, using the Kongsberg EM3002 multibeam sonar. The differing shapes of FY and MY ridges are consistent with two later high-resolution multibeam studies of specific ridges by AUV. FY ridges are found to fit the normal triangular shape template in cross-section (with a range of slope angles averaging 27°) with a relatively constant along-crest depth, and often a structure of small ice blocks can be distinguished. MY ridges, however, are often split into a number of independent solid, smooth blocks of large size, giving an irregular ridge profile which may be seemingly without linearity. Our hypothesis for this difference is that during its long lifetime an MY ridge is subjected to several episodes of crack opening; new cracks in the Arctic pack often run in straight lines across the ridges and undeformed ice alike. Such a crack will open somewhat before refreezing, interpolating a stretch of thin ice into the structure, and breaking up

  13. Tar removal during the fluidized bed gasification of plastic waste.

    PubMed

    Arena, Umberto; Zaccariello, Lucio; Mastellone, Maria Laura

    2009-02-01

    A recycled polyethylene was fed in a pilot plant bubbling fluidized bed gasifier, having an internal diameter of 0.381 m and a maximum feeding capacity of 90 kg/h. The experimental runs were carried out under various operating conditions: the bed temperature was kept at about 850 degrees C, the equivalence ratio varied between 0.2 and 0.35, the amount of bed material was between 131 and 215 kg, the fluidizing velocity was between 0.5 and 0.7 m/s, quartz sand and olivine were used as bed material, and air and steam were used as fluidizing reactants. The results confirm that the tar removal treatments applied inside the gasifier (primary methods) can eliminate or strongly reduce the need for a further downstream cleanup of the syngas. In particular, the utilization of a natural olivine as an in situ tar reduction agent remarkably improves the quality of the product gas, in terms of both high hydrogen volumetric fraction and larger syngas yield.

  14. Variational Ridging in Sea Ice Models

    NASA Astrophysics Data System (ADS)

    Roberts, A.; Hunke, E. C.; Lipscomb, W. H.; Maslowski, W.; Kamal, S.

    2017-12-01

    This work presents the results of a new development to make basin-scale sea ice models aware of the shape, porosity and extent of individual ridges within the pack. We have derived an analytic solution for the Euler-Lagrange equation of individual ridges that accounts for non-conservative forces, and therefore the compressive strength of individual ridges. Because a region of the pack is simply a collection of paths of individual ridges, we are able to solve the Euler-Lagrange equation for a large-scale sea ice field also, and therefore the compressive strength of a region of the pack that explicitly accounts for the macro-porosity of ridged debris. We make a number of assumptions that have simplified the problem, such as treating sea ice as a granular material in ridges, and assuming that bending moments associated with ridging are perturbations around an isostatic state. Regardless of these simplifications, the ridge model is remarkably predictive of macro-porosity and ridge shape, and, because our equations are analytic, they do not require costly computations to solve the Euler-Lagrange equation of ridges on the large scale. The new ridge model is therefore applicable to large-scale sea ice models. We present results from this theoretical development, as well as plans to apply it to the Regional Arctic System Model and a community sea ice code. Most importantly, the new ridging model is particularly useful for pinpointing gaps in our observational record of sea ice ridges, and points to the need for improved measurements of the evolution of porosity of deformed ice in the Arctic and Antarctic. Such knowledge is not only useful for improving models, but also for improving estimates of sea ice volume derived from altimetric measurements of sea ice freeboard.

  15. Beach-dune dynamics: Spatio-temporal patterns of aeolian sediment transport under complex offshore airflow

    NASA Astrophysics Data System (ADS)

    Lynch, K.; Jackson, D.; Delgado-Fernandez, I.; Cooper, J. A.; Baas, A. C.; Beyers, M.

    2010-12-01

    This study examines sand transport and wind speed across a beach at Magilligan Strand, Northern Ireland, under offshore wind conditions. Traditionally the offshore component of local wind regimes has been ignored when quantifying beach-dune sediment budgets, with the sheltering effect of the foredune assumed to prohibit grain entrainment on the adjoining beach. Recent investigations of secondary airflow patterns over coastal dunes have suggested this may not be the case, that the turbulent nature of the airflow in these zones enhances sediment transport potential. Beach sediment may be delivered to the dune toe by re-circulating eddies under offshore winds in coastal areas, which may explain much of the dynamics of aeolian dunes on coasts where the dominant wind direction is offshore. The present study investigated aeolian sediment transport patterns under an offshore wind event. Empirical data were collected using load cell traps, for aeolian sediment transport, co-located with 3-D ultrasonic anemometers. The instrument positioning on the sub-aerial beach was informed by prior analysis of the airflow patterns using computational fluid dynamics. The array covered a total beach area of 90 m alongshore by 65 m cross-shore from the dune crest. Results confirm that sediment transport occurred in the ‘sheltered’ area under offshore winds. Over short time and space scales the nature of the transport is highly complex; however, preferential zones for sand entrainment may be identified. Alongshore spatial heterogeneity of sediment transport seems to show a relationship to undulations in the dune crest, while temporal and spatial variations may also be related to the position of the airflow reattachment zone. These results highlight the important feedbacks between flow characteristics and transport in a complex three dimensional surface.

  16. PeaTAR1B: Characterization of a Second Type 1 Tyramine Receptor of the American Cockroach, Periplaneta americana

    PubMed Central

    Balfanz, Sabine

    2017-01-01

    The catecholamines norepinephrine and epinephrine regulate important physiological functions in vertebrates. In insects; these neuroactive substances are functionally replaced by the phenolamines octopamine and tyramine. Phenolamines activate specific guanine nucleotide-binding (G) protein-coupled receptors (GPCRs). Type 1 tyramine receptors are better activated by tyramine than by octopamine. In contrast; type 2 tyramine receptors are almost exclusively activated by tyramine. Functionally; activation of type 1 tyramine receptors leads to a decrease in the intracellular concentration of cAMP ([cAMP]i) whereas type 2 tyramine receptors can mediate Ca2+ signals or both Ca2+ signals and effects on [cAMP]i. Here; we report that the American cockroach (Periplaneta americana) expresses a second type 1 tyramine receptor (PeaTAR1B) in addition to PeaTAR1A (previously called PeaTYR1). When heterologously expressed in flpTM cells; activation of PeaTAR1B by tyramine leads to a concentration-dependent decrease in [cAMP]i. Its activity can be blocked by a series of established antagonists. The functional characterization of two type 1 tyramine receptors from P. americana; PeaTAR1A and PeaTAR1B; which respond to tyramine by changing cAMP levels; is a major step towards understanding the actions of tyramine in cockroach physiology and behavior; particularly in comparison to the effects of octopamine. PMID:29084141

  17. PeaTAR1B: Characterization of a Second Type 1 Tyramine Receptor of the American Cockroach, Periplaneta americana.

    PubMed

    Blenau, Wolfgang; Balfanz, Sabine; Baumann, Arnd

    2017-10-30

    The catecholamines norepinephrine and epinephrine regulate important physiological functions in vertebrates. In insects; these neuroactive substances are functionally replaced by the phenolamines octopamine and tyramine. Phenolamines activate specific guanine nucleotide-binding (G) protein-coupled receptors (GPCRs). Type 1 tyramine receptors are better activated by tyramine than by octopamine. In contrast; type 2 tyramine receptors are almost exclusively activated by tyramine. Functionally; activation of type 1 tyramine receptors leads to a decrease in the intracellular concentration of cAMP ([cAMP] i ) whereas type 2 tyramine receptors can mediate Ca 2+ signals or both Ca 2+ signals and effects on [cAMP] i . Here; we report that the American cockroach ( Periplaneta americana ) expresses a second type 1 tyramine receptor (PeaTAR1B) in addition to PeaTAR1A (previously called PeaTYR1). When heterologously expressed in flpTM cells; activation of PeaTAR1B by tyramine leads to a concentration-dependent decrease in [cAMP] i . Its activity can be blocked by a series of established antagonists. The functional characterization of two type 1 tyramine receptors from P. americana ; PeaTAR1A and PeaTAR1B; which respond to tyramine by changing cAMP levels; is a major step towards understanding the actions of tyramine in cockroach physiology and behavior; particularly in comparison to the effects of octopamine.

  18. Fluvial channel-belts, floodbasins, and aeolian ergs in the Precambrian Meall Dearg Formation (Torridonian of Scotland): Inferring climate regimes from pre-vegetation clastic rock records

    NASA Astrophysics Data System (ADS)

    Lebeau, Lorraine E.; Ielpi, Alessandro

    2017-07-01

    The interpretation of climate regimes from facies analysis of Precambrian clastic rocks has been challenging thus far, hindering full reconstructions of landscape dynamics in pre-vegetation environments. Yet, comparisons between different and co-active sedimentary realms, including fluvial-channelised, floodplain, and aeolian hold the potential to shed further light on this thematic. This research discusses a fluvial-aeolian record from the 1.2 Ga Meall Dearg Formation, part of the classic Torridonian succession of Scotland. Tentatively considered to date as a braided-fluvial deposit, this unit is here reappraised as the record of fluvial channel-belts, floodbasins, and aeolian ergs. Fluvial deposits with abundant transitional- to upper-flow regime structures (mostly cross-beds with tangential sets and plane/antidunal beds) and simple, low-relief sediment bars indicate a low-sinuosity, ephemeral style. Floodbasin deposits consist of plane and cross-beds ubiquitously bounded by symmetrical ripples, and rare sediment bars related to the progradation of splay complexes in temporary flooded depressions. Aeolian deposits occur nearby basement topography, and are dominated by large-scale, pin-stripe laminated cross-beds, indicative of intermountain ergs. Neither ephemeral-fluvial nor intermountain aeolian systems can be considered as reliable indicators of local climate, since their sedimentary style is respectively controlled by catchment size and shape, and basin topography relative to groundwater tables. Contrarily, the occurrence of purely clastic - rather than carbonate or evaporitic - floodplain strata can be more confidently related to humid regimes. In brief, this study provides new insight into an overlooked portion of the Torridonian succession of Scotland, and discusses climate inferences for Precambrian clastic terrestrial rocks.

  19. Aviation Turbine Fuels from Tar Sands Bitumen and Heavy Oils. Part 2. Laboratory Sample Production.

    DTIC Science & Technology

    1987-07-01

    tar sand bitumen from West Central Kentucky; and Sunnyside tar sand bitumen from the Uinta Basin , Utah. Each of the feedstocks had unique...fuel and about 50 volume percent heavy gas oil (600-1000°F). The Westken bitumen was overall the heaviest of the four feedstocks evaluated. K factors...was 40 weight percent and about 20 weight percent in the total crude. 3. San Ardo Heavy oil The San Ardo field is located in the Coastal basin of the

  20. Wind-invariant saltation heights imply linear scaling of aeolian saltation flux with shear stress.

    PubMed

    Martin, Raleigh L; Kok, Jasper F

    2017-06-01

    Wind-driven sand transport generates atmospheric dust, forms dunes, and sculpts landscapes. However, it remains unclear how the flux of particles in aeolian saltation-the wind-driven transport of sand in hopping trajectories-scales with wind speed, largely because models do not agree on how particle speeds and trajectories change with wind shear velocity. We present comprehensive measurements, from three new field sites and three published studies, showing that characteristic saltation layer heights remain approximately constant with shear velocity, in agreement with recent wind tunnel studies. These results support the assumption of constant particle speeds in recent models predicting linear scaling of saltation flux with shear stress. In contrast, our results refute widely used older models that assume that particle speed increases with shear velocity, thereby predicting nonlinear 3/2 stress-flux scaling. This conclusion is further supported by direct field measurements of saltation flux versus shear stress. Our results thus argue for adoption of linear saltation flux laws and constant saltation trajectories for modeling saltation-driven aeolian processes on Earth, Mars, and other planetary surfaces.

  1. Wind-invariant saltation heights imply linear scaling of aeolian saltation flux with shear stress

    PubMed Central

    Martin, Raleigh L.; Kok, Jasper F.

    2017-01-01

    Wind-driven sand transport generates atmospheric dust, forms dunes, and sculpts landscapes. However, it remains unclear how the flux of particles in aeolian saltation—the wind-driven transport of sand in hopping trajectories—scales with wind speed, largely because models do not agree on how particle speeds and trajectories change with wind shear velocity. We present comprehensive measurements, from three new field sites and three published studies, showing that characteristic saltation layer heights remain approximately constant with shear velocity, in agreement with recent wind tunnel studies. These results support the assumption of constant particle speeds in recent models predicting linear scaling of saltation flux with shear stress. In contrast, our results refute widely used older models that assume that particle speed increases with shear velocity, thereby predicting nonlinear 3/2 stress-flux scaling. This conclusion is further supported by direct field measurements of saltation flux versus shear stress. Our results thus argue for adoption of linear saltation flux laws and constant saltation trajectories for modeling saltation-driven aeolian processes on Earth, Mars, and other planetary surfaces. PMID:28630907

  2. Heating tar sands formations to visbreaking temperatures

    DOEpatents

    Karanikas, John Michael [Houston, TX; Colmenares, Tulio Rafael [Houston, TX; Zhang, Etuan [Houston, TX; Marino, Marian [Houston, TX; Roes, Augustinus Wilhelmus Maria [Houston, TX; Ryan, Robert Charles [Houston, TX; Beer, Gary Lee [Houston, TX; Dombrowski, Robert James [Houston, TX; Jaiswal, Namit [Houston, TX

    2009-12-22

    Methods for treating a tar sands formation are described herein. Methods may include heating at least a section of a hydrocarbon layer in the formation from a plurality of heaters located in the formation. The heat may be controlled so that at least a majority of the section reaches an average temperature of between 200.degree. C. and 240.degree. C., which results in visbreaking of at least some hydrocarbons in the section. At least some visbroken hydrocarbon fluids may be produced from the formation.

  3. Evidence that a sequence similar to TAR is important for induction of the JC virus late promoter by human immunodeficiency virus type 1 Tat.

    PubMed Central

    Chowdhury, M; Taylor, J P; Chang, C F; Rappaport, J; Khalili, K

    1992-01-01

    A specific RNA sequence located in the leader of all human immunodeficiency virus type 1 (HIV-1) mRNAs termed the transactivation response element, or TAR, is a primary target for induction of HIV-1 long terminal repeat activity by the HIV-1-derived trans-regulatory protein, Tat. Human neurotropic virus, JC virus (JCV), a causative agent of the degenerative demyelinating disease progressive multifocal leukoencephalopathy, contains sequences in the 5' end of the late RNA species with an extensive homology to HIV-1 TAR. In this study, we examined the possible role of the JCV-derived TAR-homologous sequence in Tat-mediated activation of the JCV late promoter (Tada et al., Proc. Natl. Acad. Sci. USA 87:3479-3483, 1990). Results from site-directed mutagenesis revealed that critical G residues required for the function of HIV-1 TAR that are conserved in the JCV TAR homolog play an important role in Tat activation of the JCV promoter. In addition, in vivo competition studies suggest that shared regulatory components mediate Tat activation of the JCV late and HIV-1 long terminal repeat promoters. Furthermore, we showed that the JCV-derived TAR sequence behaves in the same way as HIV-1 TAR in response to two distinct Tat mutants, one of which that has no ability to bind to HIV-1 TAR and another that lacks transcriptional activity on a responsive promoter. These results suggest that the TAR homolog of the JCV late promoter is responsive to HIV-1 Tat induction and thus may participate in the overall activation of the JCV late promoter mediated by this transactivation. Images PMID:1331525

  4. Seasonal variation of air kerma in the "Vulcano Porto" area (Aeolian Islands, Italy).

    PubMed

    Bellia, S; Basile, S; Brai, M; Hauser, S; Puccio, P; Rizzo, S

    2001-04-01

    Air kerma was measured in the "Vulcano Porto" area of the Vulcano Island, belonging to the Aeolian Islands, in the Mediterranean Sea. Measurements were carried out using thermoluminescence dosimeters. The relationship between observed dose values and source lithology has been assessed. Data show a seasonal variation due to weather conditions but also probably related to features of the soils, making the variation more evident.

  5. Cross-system nutrient transport: effects of locally-derived aeolian dust on oligotrophic lakes in West Greenland

    NASA Astrophysics Data System (ADS)

    Bullard, J. E.; Anderson, N. J.; McGowan, S.; Prater, C.; Watts, M.; Whitford, E.

    2017-12-01

    Terrestrially-derived nutrients can strongly affect production in aquatic environments. However, while some research has focused on nutrient delivery via hydrological inputs, the effects of atmospheric dry deposition are comparatively understudied. This paper examines the influence of aeolian-derived elements on water chemistry and microbial nutrient-limitation in oligotrophic lakes in West Greenland. Estimates of seasonal dust deposition and elemental leaching rates are combined with lake nutrient concentration measurements to establish the role of glacio-fluvial dust deposition in shaping nutrient stoichiometry of downwind lakes. The bioavailability of dust-associated elements is also explored using enzyme assays designed to indicate nutrient-limitation in microbial communities sampled across a dust deposition gradient. Together, these analyses demonstrate the importance of atmospheric dust inputs on hydrologically-isolated lakes found in arid high-latitude environments and demonstrate the need to better understand the role of aeolian deposition in cross-system nutrient transport.

  6. Spatial and temporal patterns of airflow across a foredune and beach surface under offshore winds: implications for aeolian sediment transport

    NASA Astrophysics Data System (ADS)

    Jackson, D.; Delgado-Fernandez, I.; Lynch, K.; Baas, A. C.; Cooper, J. A.; Beyers, M.

    2010-12-01

    The input of aeolian sediment into foredune systems from beaches represents a key component of sediment budget analysis along many soft sedimentary coastlines. Where there are significant offshore wind components in local wind regimes this is normally excluded from analysis. However, recent work has shown that if the topography of the foredune is favourable then this offshore component is steered or undergoes flow reversal through leeside eddying to give onshore transport events at the back beach under offshore flow conditions. At particular distances from the foredune crest flow reattaches to the surface to continue its incident offshore direction. The location of this reattachment point has important implications for aeolian transport of sand on the back beach and foredune toe locations. This study reports initial results where the positioning of the reattachment point is mobile and is driven by incident wind velocity (at the foredune crest) and the actual undulations of the foredune crest’s topography, dictating heterogeneous flow behaviour at the beach. Using detailed field measurements (25 Hz, three-dimensional sonic anemometry) and computational fluid dynamic modelling, a temporal and spatial pattern of reattachment positions are described. Implications for aeolian transport and dune evolution are also examined.

  7. Ridge Jumps Associated with Plume-Ridge Interaction 1: Off-axis Heating due to Lithospheric Magma Penetration

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, E.; Ito, G.

    2005-12-01

    In many hot spot-ridge systems, changes in the ridge axis geometry occur between the hot spot centers and nearby mid-ocean ridges in the form of ridge jumps. Such ridge jumps likely occur as a result of anomalous lithospheric stresses associated with mantle plume-lithosphere interaction, as well as weakening of the hot spot lithosphere due to physical and thermal thinning caused by rising buoyant asthenosphere and magma transport through the lithosphere. In this study, we use numerical models to quantify the effects of excess magmatism through the near-ridge lithosphere. Hot spot magmatism can weaken the lithosphere both mechanically through fracturing and thermally through conduction and advection of heat into the plate. Here we focus on the effects of thermal weakening. Using a plane-strain approximation, we examine deformation in a 2-D cross section of a visco-elastic-plastic lithosphere with the finite element code FLAC. The model has isothermal top and bottom boundaries and a prescribed velocity equal to the half spreading rate is imposed on the sides to drive seafloor spreading. The initial condition, as predicted for normal mid-ocean ridges, is a square root of lithospheric age cooling curve with a corner flow velocity field symmetric about the ridge axis. A range of heat inputs are introduced at various plate ages and spreading rates to simulate off-axis magma transport. To reveal the physical conditions that allow for a ridge jump and control its timing, we vary 4 parameters: spreading rate, lithospheric age, crustal thickness and heat input. Results indicate that the heating rate required to produce a ridge jump increases as a function of lithospheric age at the location of magma intrusion. The time necessary for a ridge jump to develop in lithosphere of a particular age decreases with increasing crustal thicknesses. For magma fluxes comparable to those estimated for Galapagos and Iceland, lithospheric heating by the penetrating magma alone is sufficient

  8. 27 CFR 9.182 - Ribbon Ridge.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Ribbon Ridge. (a) Name. The name of the viticultural area described in this section is “Ribbon Ridge.” (b) Approved Maps. The appropriate maps used to determine the boundaries of the Ribbon Ridge viticultural area... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Ribbon Ridge. 9.182...

  9. 27 CFR 9.182 - Ribbon Ridge.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Ribbon Ridge. (a) Name. The name of the viticultural area described in this section is “Ribbon Ridge.” (b) Approved Maps. The appropriate maps used to determine the boundaries of the Ribbon Ridge viticultural area... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Ribbon Ridge. 9.182...

  10. Comparative carcinogenic potencies of particulates from diesel engine exhausts, coke oven emissions, roofing tar aerosols and cigarette smoke.

    PubMed Central

    Albert, R E

    1983-01-01

    Mammalian cell mutagenesis, transformation and skin tumorigenesis assays show similar results in comparing the potencies of diesel, coke oven, roofing tar and cigarette smoke particulates. These assay results are reasonably consistent with the comparative carcinogenic potencies of coke oven and roofing tar emissions as determined by epidemiological studies. The bacterial mutagenesis assay tends to show disproportionately high potencies, particularly with diesel particulates. Results to date encourage the approach to the assessment for carcinogenic risks from diesel emissions based on the use of epidemiological data on cancer induced by coke oven emissions, roofing tar particulates and cigarette smoke with the comparative potencies of these materials determined by in vivo and in vitro bioassays. PMID:6186481

  11. A clarion call for aeolian research to engage with global land degradation and climate change

    NASA Astrophysics Data System (ADS)

    Chappell, Adrian; Lee, Jeffrey A.; Baddock, Matthew; Gill, Thomas E.; Herrick, Jeffrey E.; Leys, John F.; Marticorena, Beatrice; Petherick, Lynda; Schepanski, Kerstin; Tatarko, John; Telfer, Matt; Webb, Nicholas P.

    2018-06-01

    This editorial represents a clarion call for the aeolian research community to provide increased scientific input to the Intergovernmental Panel on Climate Change (IPCC) and the United Nations Convention to Combat Desertification (UNCCD) and an invitation to apply for ISAR funding to organize a working group to support this engagement.

  12. PAHs underfoot: contaminated dust from coal-tar sealcoated pavement is widespread in the United States

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

    Peter C. Van Metre; Barbara J. Mahler; Jennifer T. Wilson

    We reported in 2005 that runoff from parking lots treated with coal-tar-based sealcoat was a major source of polycyclic aromatic hydrocarbons (PAHs) to streams in Austin, Texas. Here we present new data from nine U.S. cities that show nationwide patterns in concentrations of {Sigma}PAHs associated with sealcoat. Dust was swept from parking lots in six cities in the central and eastern U.S., where coal-tar-based sealcoat dominates use, and three cities in the western U.S., where asphalt-based sealcoat dominates use. For six central and eastern cities, median SPAH concentrations in dust from sealcoated and unsealcoated pavement are 2200 and 27 mg/kg,more » respectively. For three western cities, median SPAH concentrations in dust from sealcoated and unsealcoated pavement are similar and very low (2.1 and 0.8 mg/kg, respectively). Lakes in the central and eastern cities where pavement was sampled have bottom sediments with higher PAH concentrations than do those in the western cities relative to degree of urbanization. Bottom-sediment PAH assemblages are similar to those of sealcoated pavement dust regionally, implicating coal-tar-based sealcoat as a PAH source to the central and eastern lakes. Concentrations of benzo(a)pyrene in dust from coal-tar sealcoated pavement and adjacent soils greatly exceed generic soil screening levels, suggesting that research on human-health risk is warranted. 30 refs., 4 figs., 2 tabs.« less

  13. Environmental baseline survey report for West Black Oak Ridge, East Black Oak Ridge, McKinney Ridge, West Pine Ridge and parcel 21D in the vicinity of the East Technology Park, Oak Ridge, Tennessee

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

    King, David A.

    2012-11-29

    This environmental baseline survey (EBS) report documents the baseline environmental conditions of five land parcels located near the U.S. Department of Energy?s (DOE?s) East Tennessee Technology Park (ETTP), including West Black Oak Ridge, East Black Oak Ridge, McKinney Ridge, West Pine Ridge, and Parcel 21d. Preparation of this report included the detailed search of federal government records, title documents, aerial photos that may reflect prior uses, and visual inspections of the property and adjacent properties. Interviews with current employees involved in, or familiar with, operations on the real property were also conducted to identify any areas on the property wheremore » hazardous substances and petroleum products, or their derivatives, and acutely hazardous wastes may have been released or disposed. In addition, a search was made of reasonably obtainable federal, state, and local government records of each adjacent facility where there has been a release of any hazardous substance or any petroleum product or their derivatives, including aviation fuel and motor oil, and which is likely to cause or contribute to a release of any hazardous substance or any petroleum product or its derivatives, including aviation fuel or motor oil, on the real property. A radiological survey and soil/sediment sampling was conducted to assess baseline conditions of Parcel 21d that were not addressed by the soils-only no-further-investigation (NFI) reports. Groundwater sampling was also conducted to support a Parcel 21d decision. Based on available data West Black Oak Ridge, East Black Oak Ridge, McKinney Ridge, and West Pine Ridge are not impacted by site operations and are not subject to actions per the Federal Facility Agreement (FFA). This determination is supported by visual inspections, records searches and interviews, groundwater conceptual modeling, approved NFI reports, analytical data, and risk analysis results. Parcel 21d data, however, demonstrate impacts from

  14. 27 CFR 9.129 - Arroyo Grande Valley.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Grande Valley.” (b) Approved maps. The appropriate maps for determining the boundary of Arroyo Grande..., NE, California,” edition of 1965, photorevised 1978. (2) “Tar Spring Ridge, California,” edition of... of Lopez Dam in section 32, T. 31 S., R. 14 E. (see “Tar Spring Ridge” map); (12) Then, in a...

  15. 27 CFR 9.129 - Arroyo Grande Valley.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Grande Valley.” (b) Approved maps. The appropriate maps for determining the boundary of Arroyo Grande..., NE, California,” edition of 1965, photorevised 1978. (2) “Tar Spring Ridge, California,” edition of... of Lopez Dam in section 32, T. 31 S., R. 14 E. (see “Tar Spring Ridge” map); (12) Then, in a...

  16. Increasing aeolian dust deposition to snowpacks in the Rocky Mountains inferred from snowpack, wet deposition, and aerosol chemistry

    USGS Publications Warehouse

    Clow, David W.; Williams, Mark W.; Schuster, Paul F.

    2016-01-01

    Mountain snowpacks are a vital natural resource for ∼1.5 billion people in the northern Hemisphere, helping to meet human and ecological demand for water in excess of that provided by summer rain. Springtime warming and aeolian dust deposition accelerate snowmelt, increasing the risk of water shortages during late summer, when demand is greatest. While climate networks provide data that can be used to evaluate the effect of warming on snowpack resources, there are no established regional networks for monitoring aeolian dust deposition to snow. In this study, we test the hypothesis that chemistry of snow, wet deposition, and aerosols can be used as a surrogate for dust deposition to snow. We then analyze spatial patterns and temporal trends in inferred springtime dust deposition to snow across the Rocky Mountains, USA, for 1993–2014. Geochemical evidence, including strong correlations (r2 ≥ 0.94) between Ca2+, alkalinity, and dust concentrations in snow deposited during dust events, indicate that carbonate minerals in dust impart a strong chemical signature that can be used to track dust deposition to snow. Spatial patterns in chemistry of snow, wet deposition, and aerosols indicate that dust deposition increases from north to south in the Rocky Mountains, and temporal trends indicate that winter/spring dust deposition increased by 81% in the southern Rockies during 1993–2014. Using a multivariate modeling approach, we determined that increases in dust deposition and decreases in springtime snowfall combined to accelerate snowmelt timing in the southern Rockies by approximately 7–18 days between 1993 and 2014. Previous studies have shown that aeolian dust emissions may have doubled globally during the 20th century, possibly due to drought and land-use change. Climate projections for increased aridity in the southwestern U.S., northern Africa, and other mid-latitude regions of the northern Hemisphere suggest that aeolian dust emissions may continue to

  17. Ridges and tidal stress on Io

    USGS Publications Warehouse

    Bart, G.D.; Turtle, E.P.; Jaeger, W.L.; Keszthelyi, L.P.; Greenberg, R.

    2004-01-01

    Sets of ridges of uncertain origin are seen in twenty-nine high-resolution Galileo images, which sample seven locales on Io. These ridges are on the order of a few kilometers in length with a spacing of about a kilometer. Within each locale, the ridges have a consistent orientation, but the orientations vary from place to place. We investigate whether these ridges could be a result of tidal flexing of Io by comparing their orientations with the peak tidal stress orientations at the same locations. We find that ridges grouped near the equator are aligned either north-south or east-west, as are the predicted principal stress orientations there. It is not clear why particular groups run north-south and others east-west. The one set of ridges observed far from the equator (52?? S) has an oblique azimuth, as do the tidal stresses at those latitudes. Therefore, all observed ridges have similar orientations to the tidal stress in their region. This correlation is consistent with the hypothesis that tidal flexing of Io plays an important role in ridge formation. ?? 2004 Elsevier Inc. All rights reserved.

  18. Aeolian bedforms, yardangs, and indurated surfaces in the Tharsis Montes as seen by the HiRISE Camera: Evidence for dust aggregates

    USGS Publications Warehouse

    Bridges, N.T.; Banks, M.E.; Beyer, R.A.; Chuang, F.C.; Noe Dobrea, E.Z.; Herkenhoff, K. E.; Keszthelyi, L.P.; Fishbaugh, K.E.; McEwen, A.S.; Michaels, T.I.; Thomson, B.J.; Wray, J.J.

    2010-01-01

    HiRISE images of Mars with ground sampling down to 25 cm/pixel show that the dust-rich mantle covering the surfaces of the Tharsis Montes is organized into ridges whose form and distribution are consistent with formation by aeolian saltation. Other dusty areas near the volcanoes and elsewhere on the planet exhibit a similar morphology. The material composing these "reticulate" bedforms is constrained by their remote sensing properties and the threshold curve combined with the saltation/suspension boundary, both of which vary as a function of elevation (atmospheric pressure), particle size, and particle composition. Considering all of these factors, dust aggregates are the most likely material composing these bedforms. We propose that airfall dust on and near the volcanoes aggregates in situ over time, maybe due to electrostatic charging followed by cementation by salts. The aggregates eventually reach a particle size at which saltation is possible. Aggregates on the flanks are transported downslope by katabatic winds and form linear and "accordion" morphologies. Materials within the calderas and other depressions remain trapped and are subjected to multidirectional winds, forming an interlinked "honeycomb" texture. In many places on and near the volcanoes, light-toned, low thermal inertia yardangs and indurated surfaces are present. These may represent "duststone" formed when aggregates reach a particle size below the threshold curve, such that they become stabilized and subsequently undergo cementation. ?? 2009 Elsevier Inc.

  19. Ridge 2000 Data Management System

    NASA Astrophysics Data System (ADS)

    Goodwillie, A. M.; Carbotte, S. M.; Arko, R. A.; Haxby, W. F.; Ryan, W. B.; Chayes, D. N.; Lehnert, K. A.; Shank, T. M.

    2005-12-01

    Hosted at Lamont by the marine geoscience Data Management group, mgDMS, the NSF-funded Ridge 2000 electronic database, http://www.marine-geo.org/ridge2000/, is a key component of the Ridge 2000 multi-disciplinary program. The database covers each of the three Ridge 2000 Integrated Study Sites: Endeavour Segment, Lau Basin, and 8-11N Segment. It promotes the sharing of information to the broader community, facilitates integration of the suite of information collected at each study site, and enables comparisons between sites. The Ridge 2000 data system provides easy web access to a relational database that is built around a catalogue of cruise metadata. Any web browser can be used to perform a versatile text-based search which returns basic cruise and submersible dive information, sample and data inventories, navigation, and other relevant metadata such as shipboard personnel and links to NSF program awards. In addition, non-proprietary data files, images, and derived products which are hosted locally or in national repositories, as well as science and technical reports, can be freely downloaded. On the Ridge 2000 database page, our Data Link allows users to search the database using a broad range of parameters including data type, cruise ID, chief scientist, geographical location. The first Ridge 2000 field programs sailed in 2004 and, in addition to numerous data sets collected prior to the Ridge 2000 program, the database currently contains information on fifteen Ridge 2000-funded cruises and almost sixty Alvin dives. Track lines can be viewed using a recently- implemented Web Map Service button labelled Map View. The Ridge 2000 database is fully integrated with databases hosted by the mgDMS group for MARGINS and the Antarctic multibeam and seismic reflection data initiatives. Links are provided to partner databases including PetDB, SIOExplorer, and the ODP Janus system. Improved inter-operability with existing and new partner repositories continues to be

  20. Mid-ocean ridge jumps associated with hotspot magmatism

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, Eric; Ito, Garrett; Behn, Mark D.

    2008-02-01

    Hotspot-ridge interaction produces a wide range of phenomena including excess crustal thickness, geochemical anomalies, off-axis volcanic ridges and ridge relocations or jumps. Ridges are recorded to have jumped toward many hotspots including, Iceland, Discovery, Galápagos, Kerguelen and Tristan de Cuhna. The causes of ridge jumps likely involve a number of interacting processes related to hotspots. One such process is reheating of the lithosphere as magma penetrates it to feed near-axis volcanism. We study this effect by using the hybrid, finite-element code, FLAC, to simulate two-dimensional (2-D, cross-section) viscous mantle flow, elasto-plastic deformation of the lithosphere and heat transport in a ridge setting near an off-axis hotspot. Heating due to magma transport through the lithosphere is implemented within a hotspot region of fixed width. To determine the conditions necessary to initiate a ridge jump, we vary four parameters: hotspot magmatic heating rate, spreading rate, seafloor age at the location of the hotspot and ridge migration rate. Our results indicate that the hotspot magmatic heating rate required to initiate a ridge jump increases non-linearly with increasing spreading rate and seafloor age. Models predict that magmatic heating, itself, is most likely to cause jumps at slow spreading rates such as at the Mid-Atlantic Ridge on Iceland. In contrast, despite the higher magma flux at the Galápagos hotspot, magmatic heating alone is probably insufficient to induce a ridge jump at the present-day due to the intermediate ridge spreading rate of the Galápagos Spreading Center. The time required to achieve a ridge jump, for fixed or migrating ridges, is found to be on the order of 10 5-10 6 years. Simulations that incorporate ridge migration predict that after a ridge jump occurs the hotspot and ridge migrate together for time periods that increase with magma flux. Model results also suggest a mechanism for ridge reorganizations not related to

  1. MultiMiTar: a novel multi objective optimization based miRNA-target prediction method.

    PubMed

    Mitra, Ramkrishna; Bandyopadhyay, Sanghamitra

    2011-01-01

    Machine learning based miRNA-target prediction algorithms often fail to obtain a balanced prediction accuracy in terms of both sensitivity and specificity due to lack of the gold standard of negative examples, miRNA-targeting site context specific relevant features and efficient feature selection process. Moreover, all the sequence, structure and machine learning based algorithms are unable to distribute the true positive predictions preferentially at the top of the ranked list; hence the algorithms become unreliable to the biologists. In addition, these algorithms fail to obtain considerable combination of precision and recall for the target transcripts that are translationally repressed at protein level. In the proposed article, we introduce an efficient miRNA-target prediction system MultiMiTar, a Support Vector Machine (SVM) based classifier integrated with a multiobjective metaheuristic based feature selection technique. The robust performance of the proposed method is mainly the result of using high quality negative examples and selection of biologically relevant miRNA-targeting site context specific features. The features are selected by using a novel feature selection technique AMOSA-SVM, that integrates the multi objective optimization technique Archived Multi-Objective Simulated Annealing (AMOSA) and SVM. MultiMiTar is found to achieve much higher Matthew's correlation coefficient (MCC) of 0.583 and average class-wise accuracy (ACA) of 0.8 compared to the others target prediction methods for a completely independent test data set. The obtained MCC and ACA values of these algorithms range from -0.269 to 0.155 and 0.321 to 0.582, respectively. Moreover, it shows a more balanced result in terms of precision and sensitivity (recall) for the translationally repressed data set as compared to all the other existing methods. An important aspect is that the true positive predictions are distributed preferentially at the top of the ranked list that makes MultiMiTar

  2. Analytical Determination of Nicotine and Tar Levels in Various Dokha and Shisha Tobacco Products.

    PubMed

    Mahboub, Bassam; Mohammad, Ayesha Begum; Nahlé, Ayssar; Vats, Mayank; Al Assaf, Omar; Al-Zarooni, Hamdan

    2018-05-10

    In the Middle East, there is no precise data and literature on tobacco-based products, such as dokha and shisha. The proposed study aims to quantify the levels of nicotine and tar in different kinds of dokha and shisha products that are sold in the local marketplace. The amount of nicotine in dokha and shisha products can be quantitatively determined using a combination of the "kissling" and "silicotungstic acid" method proposed by Robert M. Chapin. The tar residue from the smoke sample was collected on a glass wool placed before the stopcock (tap) of a separatory funnel as the smoke passes through the inlet of an electronically controlled vacuum pump. The nicotine levels in dokha and shisha samples ranged from 23.83 to 52.80 mg/g and 0.80 to 20.52 mg/g, respectively. The nicotine level varies between different tobacco products. It varies from 0.5 to 19.5 mg/g in cigarettes, from 10.3 to 23.1 mg/g in snuff tobacco, from 11 to 18 mg/g in electronic cigarettes and from 2.9 to 16.6 mg/g in chewing tobacco. The tar levels in the dokha and shisha samples ranged from 21.6 to 45.02 mg/g and 1.68 to 11.87 mg/g, respectively. Smokers are at a high risk of getting lung cancer, chronic obstructive pulmonary disease, emphysema and coronary artery disease owing to the high levels of nicotine and tar present in dokha and shisha tobacco products. These findings contradict the widespread belief among teenagers that dokha and shisha tobacco products are safer alternatives to cigarettes.

  3. A wind tunnel study of aeolian sediment transport response to unsteady winds

    NASA Astrophysics Data System (ADS)

    Li, Bailiang; McKenna Neuman, Cheryl

    2014-06-01

    Although moderate attention has been paid to the response of the aeolian mass transport rate to wind gusts, it is still unclear how the particle size and volumetric concentration affect this relation. Very little is known about the response time of the particle speed, and specifically, how the sensor scale and elevation affect measurements of this variable. The present study addresses this knowledge gap through a series of wind tunnel experiments in which a gusty wind was generated by programming the fan motor to adjust to a randomly selected rpm every 10 s. Beds consisting of either medium or coarse sand were investigated through synchronous, co-located measurements of the local wind speed and particle speed/count rate obtained via a customized laser Doppler anemometry (LDA) system. The vertically integrated sand transport rate (Q) and the wind speed in the freestream were quantified using a passive sand trap and pitot tube, respectively. The results of the experiments indicate that the response of the aeolian transport system to wind gusts is generally faster in terms of the particle speed than the mass transport rate, while the degree of correlation is found to vary with the sensor elevation, as well as with the particle size and volumetric concentration. In essence, the coupling within the transport system is demonstrated to be strongly scale dependent.

  4. Selected constituents in the smokes of foreign commercial cigaretts: tar, nicotine, carbon monoxide, and carbon dioxide

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

    Jenkins, R.A.; Quincy, R.B.; Guerin, M.R.

    The tar, nicotine, carbon monoxide, and carbon dioxide contents of the smokes of 220 brands of foreign commercial cigarettes are reported. In some instances, filter cigarettes of certain brands were found to deliver as much or more smoke constituents than their nonfilter counterparts. Also, data indicated that there can be a great variation in the tar, nicotine, or carbon monoxide content of the smoke of samples of a given brand of cigarettes, depending on the nation in which they are purchased. 24 tables.

  5. Downwind changes in grain size of aeolian dust; examples from marine and terrestrial archives

    NASA Astrophysics Data System (ADS)

    Stuut, Jan-Berend; Prins, Maarten

    2013-04-01

    Aeolian dust in the atmosphere may have a cooling effect when small particles in the high atmosphere block incoming solar energy (e.g., Claquin et al., 2003) but it may also act as a 'greenhouse gas' when larger particles in the lower atmosphere trap energy that was reflected from the Earth's surface (e.g., Otto et al., 2007). Therefore, it is of vital importance to have a good understanding of the particle-size distribution of aeolian dust in space and time. As wind is a very size-selective transport mechanism, the sediments it carries typically have a very-well sorted grain-size distribution, which gradually fines from proximal to distal deposition sites. This fact has been used in numerous paleo-environmental studies to both determine source-to-sink changes in the particle size of aeolian dust (e.g., Weltje and Prins, 2003; Holz et al., 2004; Prins and Vriend, 2007) and to quantify mass-accumulation rates of aeolian dust (e.g., Prins and Weltje 1999; Stuut et al., 2002; Prins et al., 2007; Prins and Vriend, 2007; Stuut et al., 2007; Tjallingii et al., 2008; Prins et al., 2009). Studies on modern wind-blown particles have demonstrated that particle size of dust not only is a function of lateral but also vertical transport distance (e.g., Torres-Padron et al., 2002; Stuut et al., 2005). Nonetheless, there are still many unresolved questions related to the physical properties of wind-blown particles like e.g., the case of "giant" quartz particles found on Hawaii (Betzer et al., 1988) that can only originate from Asia but have a too large size for the distance they travelled through the atmosphere. Here, we present examples of dust particle-size distributions from terrestrial (loess) as well as marine (deep-sea sediments) sedimentary archives and their spatial and temporal changes. With this contribution we hope to provide quantitative data for the modelling community in order to get a better grip on the role of wind-blown particles in the climate system. Cited

  6. Braidplain, floodplain and playa lake, alluvial-fan, aeolian and palaeosol facies composing a diversified lithogenetical sequence in the permian and triassic of South Devon (England)

    NASA Astrophysics Data System (ADS)

    Mader, Detlef

    flat seaming the toes of the fan chain. Sedimentation is characterized by flashy discharge with many episodic flood pulses of short periodicity and mainly rapid waning of high-water phases with quick underrunning of the threshold velocity for keeping the large clasts rolling. Pronounced slack water episodes allow occasionally the draping of gravel sheets with thin veneers of waning-flow and stagnant-water fines. Spectacular invertebrate burrows in finer breccias underline the flashy nature of most of the flood and flow events, allowing the colonization of the sediments with ground-living invertebrates during interruptions of transport and accumulation. Some peculiar dewatering structures being infilling of crack systems in breccias with wash-load sand are probably induced by earthquake shocks thus pointing to the active tectonic setting of the depositional area. Aeolian sands originate as transverse dune ridges in restricted dune fields and extensive sand seas and as sheet sands in interdune playa depressions. Associated mudstones and ventifact gravel form in wet interdunes or in playa lakes and in deflationary interdunes, respectively. Accumulation of aeolian dunes and interdune sheet sands takes place by both spreading out of drapes on flats and infilling of abandoned fluvial channels which enhance the trapping of sand by topographical effects. The dunes and wind ripple trains migrate across dry interdune floors under predominantly unidirectional winds. Sedimentary processes are grainfall and grainflow on the lee slope of dunes and subcritical climbing of wind ripples. Episodical wetting and dampening of dry interdune flats by intermittent rainfall, periodical dew and even ephemeral fluvial or alluvial-fan incursions allow formation of adhesion-rippled sands on damp surfaces and origin of sandy and silty-clayey lacustrine sediments in shallow water veneers of the flooded playa. Aquatic modification of aeolian sands by invading flood surges of atmospheric or alluvial

  7. Occurrence of Somma-Vesuvio fine ashes in the tephrostratigraphic record of Panarea, Aeolian Islands

    NASA Astrophysics Data System (ADS)

    Donatella, De Rita; Daniela, Dolfi; Corrado, Cimarelli

    2008-10-01

    Ash-rich tephra layers interbedded in the pyroclastic successions of Panarea island (Aeolian archipelago, Southern Italy) have been analyzed and related to their original volcanic sources. One of these tephra layers is particularly important as it can be correlated by its chemical and morphoscopic characteristics to the explosive activity of Somma-Vesuvio. Correlation with the Pomici di Base eruption, that is considered one of the largest explosive events causing the demolition of the Somma stratovolcano, seems the most probable. The occurrence on Panarea island of fine ashes related to this eruption is of great importance for several reasons: 1) it allows to better constrain the time stratigraphy of the Panarea volcano; 2) it provides a useful tool for tephrochronological studies in southern Italy and finally 3) it allows to improve our knowledge on the distribution of the products of the Pomici di Base eruption giving new insights on the dispersion trajectories of fine ashes from plinian plumes. Other exotic tephra layers interbedded in the Panarea pyroclastic successions have also been found. Chemical and sedimentological characteristics of these layers allow their correlation with local vents from the Aeolian Islands thus constraining the late explosive activity of Panarea dome.

  8. Cross-bedding Related Anisotropy and its Role in the Orientation of Joints in an Aeolian Sandstone

    NASA Astrophysics Data System (ADS)

    Deng, S.; Cilona, A.; Mapeli, C.; Panfilau, A.; Aydin, A.; Prasad, M.

    2014-12-01

    Previous research revealed that the cross-bedding related anisotropy in aeolian sandstones affects the orientation of compaction bands, also known as anticracks. We hypothesize that cross-bedding should a have similar influence on the orientation of the joints within the same rock at the same location. To test this hypothesis, we investigated the relationship between the cross-beds and the cross-bed package confined joints in the Jurassic aeolian Aztec Sandstone cropping out in the Valley of Fire State Park, Nevada. The field data demonstrates that the cross-bed package confined joints occur at high-angle to bedding and trend roughly parallel to the dip direction of the cross-beds. This shows that the cross-bed orientation and the associated anisotropy also exert a strong control on the formation and orientation of the joints. In order to characterize the anisotropy due to cross-bedding in the Aztec Sandstone, we measured the P-wave velocities parallel and perpendicular to bedding from 11 samples in the laboratory using a bench-top ultrasonic assembly. The measured P-wave anisotropy is about 13% on average. Based on these results, a numerical model based on the generalized Hooke's law for anisotropic materials is analyzed assuming the cross-bedded sandstone to be transversely isotropic. Using this model, we tested various cross-bed orientations as well as different strain boundary conditions (uniaxial, axisymmetric and triaxial). It is possible to define a boundary condition under which the modeled results roughly match with the observed relationship between cross-bed package confined joints and cross-beds. These results have important implications for fluid flow through aeolian sandstones in reservoirs and aquifers.

  9. Ridge Regression Signal Processing

    NASA Technical Reports Server (NTRS)

    Kuhl, Mark R.

    1990-01-01

    The introduction of the Global Positioning System (GPS) into the National Airspace System (NAS) necessitates the development of Receiver Autonomous Integrity Monitoring (RAIM) techniques. In order to guarantee a certain level of integrity, a thorough understanding of modern estimation techniques applied to navigational problems is required. The extended Kalman filter (EKF) is derived and analyzed under poor geometry conditions. It was found that the performance of the EKF is difficult to predict, since the EKF is designed for a Gaussian environment. A novel approach is implemented which incorporates ridge regression to explain the behavior of an EKF in the presence of dynamics under poor geometry conditions. The basic principles of ridge regression theory are presented, followed by the derivation of a linearized recursive ridge estimator. Computer simulations are performed to confirm the underlying theory and to provide a comparative analysis of the EKF and the recursive ridge estimator.

  10. Sea ice ridging in the eastern Weddell Sea

    NASA Astrophysics Data System (ADS)

    Lytle, V. I.; Ackley, S. F.

    1991-10-01

    In August 1986, sea ice ridge heights and spatial frequency in the eastern Weddell Sea were measured using a ship-based acoustical sounder. Using a minimum ridge sail height of 0.75 m, a total of 933 ridges were measured along a track length of 415 km. The ridge frequency varied from 0.4 to 10.5 ridges km-1. The mean height of the ridges was found to be about 1.1 m regardless of the ridge frequency. These results are compared to other ridging statistics from the Ross Sea and found to be similar. Comparison with Arctic data, however, indicates that the height and frequency of the ridges are considerably less in the Weddell Sea than in the Arctic. Whereas in the Arctic the mean ridge height tends to increase with the ridge frequency, we found that this was not the case in the Weddell Sea, where the mean ridge height remained constant irrespective of the ridge frequency. Estimates of the contribution of deformed ice to the total ice thickness are generally low except for a single 53-km section where the ridge frequency increased by an order of magnitude. This resulted in an increase in the equivalent mean ice thickness due to ridging from 0.04 m in the less deformed areas to 0.45 m in the highly deformed section. These values were found to be consistent with values obtained from drilled profile lines during the same cruise.

  11. [Comparative study of N, P output and eutrophication risk in runoff water in cross ridge and longitudinal ridge].

    PubMed

    Yu, Xing-Xiu; Ma, Qian; Liu, Qian-Jin; Lü, Guo-An

    2011-02-01

    Field in-situ rainfall simulation tests with two rainfall intensities (40 mm x h(-1) and 70 mm x h(-1)), which were conducted at typical sloping cropland in Yimeng mountainous area, were designed to analyze the output characteristics of dissolved inorganic nitrogen, Inorganic-N (NO3(-)-N, NH4(+) -N) and dissolved phosphorus (DP) in runoff water, as well as to compare the eutrophication risk in this water by calculating three ratios of Inorganic-N/DP, NO3(-) -N/DP, and NH4(+)-N/DP, respectively, in cross ridge and longitudinal ridge tillage methods. Results showed that, under the same rainfall intensity, the DP level in runoff water was higher in cross ridge than longitudinal ridge, while the change of different Inorganic-N level between the two tillage methods were not consistent. Cross ridge could effectively reduce runoff and the output rate of Inorganic-N and DP when compared to the longitudinal ridge tillage, which would be more outstanding with the increases of rainfall intensities. The losses of Inorganic-N and DP in runoff water were 43% and 5% less, respectively, in cross ridge than longitudinal ridge at the 40 mm x h(-1) rainfall intensity, and were 68% and 55%, respectively, at 70 mm x h(-1). The higher Inorganic-N/DP and NO3(-) -N/DP ratios suggest that runoff water from either cross ridge or longitudinal ridge tillage have a certain eutrophication risk, which present an increasing trend during the precipitation-runoff process. Compared with longitudinal ridge, cross ridge can not only hinder the increasing trend of eutrophication risk, but also can significantly lower it, and thus effectively reduce the effect of sloping cropland runoff on the eutrophication processes of receiving waters.

  12. Comparison of buried sand ridges and regressive sand ridges on the outer shelf of the East China Sea

    NASA Astrophysics Data System (ADS)

    Wu, Ziyin; Jin, Xianglong; Zhou, Jieqiong; Zhao, Dineng; Shang, Jihong; Li, Shoujun; Cao, Zhenyi; Liang, Yuyang

    2017-06-01

    Based on multi-beam echo soundings and high-resolution single-channel seismic profiles, linear sand ridges in U14 and U2 on the East China Sea (ECS) shelf are identified and compared in detail. Linear sand ridges in U14 are buried sand ridges, which are 90 m below the seafloor. It is presumed that these buried sand ridges belong to the transgressive systems tract (TST) formed 320-200 ka ago and that their top interface is the maximal flooding surface (MFS). Linear sand ridges in U2 are regressive sand ridges. It is presumed that these buried sand ridges belong to the TST of the last glacial maximum (LGM) and that their top interface is the MFS of the LGM. Four sub-stage sand ridges of U2 are discerned from the high-resolution single-channel seismic profile and four strikes of regressive sand ridges are distinguished from the submarine topographic map based on the multi-beam echo soundings. These multi-stage and multi-strike linear sand ridges are the response of, and evidence for, the evolution of submarine topography with respect to sea-level fluctuations since the LGM. Although the difference in the age of formation between U14 and U2 is 200 ka and their sequences are 90 m apart, the general strikes of the sand ridges are similar. This indicates that the basic configuration of tidal waves on the ECS shelf has been stable for the last 200 ka. A basic evolutionary model of the strata of the ECS shelf is proposed, in which sea-level change is the controlling factor. During the sea-level change of about 100 ka, five to six strata are developed and the sand ridges develop in the TST. A similar story of the evolution of paleo-topography on the ECS shelf has been repeated during the last 300 ka.

  13. Polycyclic aromatic hydrocarbon (PAHs) and hopanes in stranded tar-balls on the coasts of Peninsular Malaysia: applications of biomarkers for identifying sources of oil pollution.

    PubMed

    Zakaria, M P; Okuda, T; Takada, H

    2001-12-01

    Malaysian coasts are subjected to various threats of petroleum pollution including routine and accidental oil spill from tankers, spillage of crude oils from inland and off-shore oil fields, and run-off from land-based human activities. Due to its strategic location, the Straits of Malacca serves as a major shipping lane. This paper expands the utility of biomarker compounds, hopanes, in identifying the source of tar-balls stranded on Malaysian coasts. 20 tar-ball samples collected from the east and west coast were analyzed for hopanes and polycyclic aromatic hydrocarbons (PAHs). Four of the 13 tar-ball samples collected from the west coast of Peninsular Malaysia were identified as the Middle East crude oil (MECO) based on their biomarker signatures, suggesting tanker-derived sources significantly contributing the petroleum pollution in the Straits of Malacca. The tar-balls found on the east coast seem to originate from the offshore oil platforms in the South China Sea. The presence of South East Asian crude oil (SEACO) tar-balls on the west coast carry several plausible explanations. Some of the tar-balls could have been transported via sea currents from the east coast. The tankers carrying SEACO to other countries could have accidentally spilt the oil as well. Furthermore, discharge of tank washings and ballast water from the tankers were suggested based on the abundance in higher molecular weight n-alkanes and the absence of unresolved complex mixture (UCM) in the tar-ball samples. The other possibilities are that the tar-balls may have been originated from the Sumatran oil fields and spillage of domestic oil from oil refineries in Port Dickson and Malacca. The results of PAHs analysis suggest that all the tar-ball samples have undergone various extent of weathering through evaporation, dissolution and photooxidation.

  14. Heating tar sands formations while controlling pressure

    DOEpatents

    Stegemeier, George Leo [Houston, TX; Beer, Gary Lee [Houston, TX; Zhang, Etuan [Houston, TX

    2010-01-12

    Methods for treating a tar sands formation are described herein. Methods may include heating at least a section of a hydrocarbon layer in the formation from a plurality of heaters located in the formation. A pressure in the majority of the section may be maintained below a fracture pressure of the formation. The pressure in the majority of the section may be reduced to a selected pressure after the average temperature reaches a temperature that is above 240.degree. C. and is at or below pyrolysis temperatures of hydrocarbons in the section. At least some hydrocarbon fluids may be produced from the formation.

  15. Wrinkle ridges of Arcadia Planitia, Mars

    NASA Technical Reports Server (NTRS)

    Plescia, J. B.

    1993-01-01

    Wrinkle ridges of Arcadia Planitia were examined to determine their morphology, spatial distribution, and the amount of crustal shortening and strain they accommodate. Ridges trend generally northward, but their orientation and distribution are strongly controlled by the relief of the underlying hobby material. Ridges begin or end at inselbergs of older terrain and are associated with buried craters. Arcadia Planitia ridges have an average width of 3425 m and accommodate an average folding shortening of 3 m and a faulting shortening of 55 m; mean total shortening is 57 m. Three east-west transects were constructed at 20 deg 25 deg and 28 deg N to estimate regional shortening and strain. Average total shortening across the transects is about 900 m, corresponding to a regional compressive strain of 0.06 percent. The total shortening and compression across Arcadia Planitia are less than in Lungae Planum. Faults associated with the Arcadia ridges are inferred to have a westward dip compared with an eastward dip for Lungae Planum ridges. The general levels of compression and symmetric orientation of the ridges suggest a regionally organized stress system.

  16. Trace elements in ocean ridge basalts

    NASA Technical Reports Server (NTRS)

    Kay, R. W.; Hubbard, N. J.

    1978-01-01

    A study is made of the trace elements found in ocean ridge basalts. General assumptions regarding melting behavior, trace element fractionation, and alteration effects are presented. Data on the trace elements are grouped according to refractory lithophile elements, refractory siderophile elements, and volatile metals. Variations in ocean ridge basalt chemistry are noted both for regional and temporal characteristics. Ocean ridge basalts are compared to other terrestrial basalts, such as those having La/Yb ratios greater than those of chondrites, and those having La/Yb ratios less than those of chondrites. It is found that (1) as compared to solar or chondrite ratios, ocean ridge basalts have low ratios of large, highly-charged elements to smaller less highly-charged elements, (2) ocean ridge basalts exhibit low ratios of volatile to nonvolatile elements, and (3) the transition metals Cr through Zn in ocean ridge basalts are not fractionated more than a factor of 2 or 3 from the chondritic abundance ratios.

  17. Global survey of lunar wrinkle ridge formation times

    NASA Astrophysics Data System (ADS)

    Yue, Z.; Michael, G. G.; Di, K.; Liu, J.

    2017-11-01

    Wrinkle ridges are a common feature of the lunar maria and record subsequent contraction of mare infill. Constraining the timing of wrinkle ridge formation from crater counts is challenging because they have limited areal extent and it is difficult to determine whether superposed craters post-date ridge formation or have alternatively been uplifted by the deformation. Some wrinkle ridges do allow determination to be made. This is possible where a ridge shows a sufficiently steep boundary or scarp that can be identified as deforming an intersecting crater or the crater obliterates the relief of the ridge. Such boundaries constitute only a small fraction of lunar wrinkle ridge structures yet they are sufficiently numerous to enable us to obtain statistically significant crater counts over systems of structurally related wrinkle ridges. We carried out a global mapping of mare wrinkle ridges, identifying appropriate boundaries for crater identification, and mapping superposed craters. Selected groups of ridges were analyzed using the buffered crater counting method. We found that, except for the ridges in mare Tranquilitatis, the ridge groups formed with average ages between 3.5 and 3.1 Ga ago, or 100-650 Ma after the oldest observable erupted basalts where they are located. We interpret these results to suggest that local stresses from loading by basalt fill are the principal agent responsible for the formation of lunar wrinkle ridges, as others have proposed. We find a markedly longer interval before wrinkle ridge formation in Tranquilitatis which likely indicates a different mechanism of stress accumulation at this site.

  18. Cancer risk from incidental ingestion exposures to PAHs associated with coal-tar-sealed pavement

    USGS Publications Warehouse

    Williams, E. Spencer; Mahler, Barbara J.; Van Metre, Peter C.

    2012-01-01

    Recent (2009-10) studies documented significantly higher concentrations of polycyclic aromatic hydrocarbons (PAHs) in settled house dust in living spaces and soil adjacent to parking lots sealed with coal-tar-based products. To date, no studies have examined the potential human health effects of PAHs from these products in dust and soil. Here we present the results of an analysis of potential cancer risk associated with incidental ingestion exposures to PAHs in settings near coal-tar-sealed pavement. Exposures to benzo[a]pyrene equivalents were characterized across five scenarios. The central tendency estimate of excess cancer risk resulting from lifetime exposures to soil and dust from nondietary ingestion in these settings exceeded 1 × 10–4, as determined using deterministic and probabilistic methods. Soil was the primary driver of risk, but according to probabilistic calculations, reasonable maximum exposure to affected house dust in the first 6 years of life was sufficient to generate an estimated excess lifetime cancer risk of 6 × 10–5. Our results indicate that the presence of coal-tar-based pavement sealants is associated with significant increases in estimated excess lifetime cancer risk for nearby residents. Much of this calculated excess risk arises from exposures to PAHs in early childhood (i.e., 0–6 years of age).

  19. Comprehensive GC²/MS for the monitoring of aromatic tar oil constituents during biodegradation in a historically contaminated soil.

    PubMed

    Vasilieva, Viktoriya; Scherr, Kerstin E; Edelmann, Eva; Hasinger, Marion; Loibner, Andreas P

    2012-02-20

    The constituents of tar oil comprise a wide range of physico-chemically heterogeneous pollutants of environmental concern. Besides the sixteen polycyclic aromatic hydrocarbons defined as priority pollutants by the US-EPA (EPA-PAHs), a wide range of substituted (NSO-PAC) and alkylated (alkyl-PAC) aromatic tar oil compounds are gaining increased attention for their toxic, carcinogenic, mutagenic and/or teratogenic properties. Investigations on tar oil biodegradation in soil are in part hampered by the absence of an efficient analytical tool for the simultaneous analysis of this wide range of compounds with dissimilar analytical properties. Therefore, the present study sets out to explore the applicability of comprehensive two-dimensional gas chromatography (GC²/MS) for the simultaneous measurement of compounds with differing polarity or that are co-eluting in one-dimensional systems. Aerobic tar oil biodegradation in a historically contaminated soil was analyzed over 56 days in lab-scale bioslurry tests. Forty-three aromatic compounds were identified with GC²/MS in one single analysis. The number of alkyl chains on a molecule was found to prime over alkyl chain length in hampering compound biodegradation. In most cases, substitution of carbon with nitrogen and oxygen was related to increased compound degradation in comparison to unalkylated and sulphur- or unsubstituted PAH with a similar ring number.The obtained results indicate that GC²/MS can be employed for the rapid assessment of a large variety of structurally heterogeneous environmental contaminants. Its application can contribute to facilitate site assessment, development and control of microbial cleanup technologies for tar oil contaminated sites. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Ridge interaction features of the Line Islands

    NASA Astrophysics Data System (ADS)

    Konter, J. G.; Koppers, A. A. P.; Storm, L. P.

    2016-12-01

    The sections of Pacific absolute plate motion history that precede the Hawaii-Emperor and Louisville chains are based on three chains: the Line Islands-Mid-Pacific Mountains, the Hess Rise-Shatsky Rise, and the Marshall Islands-Wake Islands (Rurutu hotspot). Although it has been clear that the Line Islands do not define a simple age progression (e.g. Schlanger et al., 1984), the apparent similarity to the Emperor Seamount geographic trend has been used to extend the overall Hawaii-Emperor track further into the past. However, we show here that plate tectonic reconstructions suggest that the Mid-Pacific Mountains (MPMs) and Line Islands (LIs) were erupted near a mid-ocean ridge, and thus these structures do not reflect absolute plate motion. Moverover, the morphology and geochemistry of the volcanoes show similarities with Pukapuka Ridge (e.g. Davis et al., 2002) and the Rano Rahi seamounts, presumed to have a shallow origin. Modern 40Ar/39Ar ages show that the LIs erupted at various times along the entire volcanic chain. The oldest structures formed within 10 Ma of plate formation. Given the short distance to the ridge system, large aseismic volcanic ridges, such as Necker Ridge and Horizon Guyot may simply reflect a connection between MPMs and the ridge, similar to the Pukapuka Ridge. The Line Islands to the south (including Karin Ridge) define short subchains of elongated seamounts that are widespread, resembling the Rano Rahi seamount field. During this time, the plate moved nearly parallel to the ridge system. The change from few large ridges to many subchains may reflect a change in absolute plate motion, similar to the Rano Rahi field. Here, significant MPMs volcanism is no longer connected to the ridge along plate motion. Similar to Pukapuka vs. Rano Rahi, the difference in direction between plate motion and the closest ridge determines whether larger ridges or smaller seamount subchains are formed. The difference between the largest structures (MPMs and LIs

  1. Surface radiological investigations at White Wing Scrap Yard, Oak Ridge Reservation, Oak Ridge, Tennessee

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

    Williams, J.K.; Rodriguez, R.E.; Uziel, M.S.

    1991-09-01

    A surface radiological scoping survey of accessible areas at the White Wing Scrap Yard (Waste Area Grouping 11 (WAG 11)) was conducted intermittently from December 1989 through July 1991 by members of the Measurement Applications and Development Group, Health and Safety Research Division, Oak Ridge National Laboratory (ORNL) at the request of Environmental Restoration Program personnel at ORNL. The White Wing Scrap Yard is an estimated 30-acre, predominately wooded area located on the western edge of East Fork Ridge in the McNew Hollow area on the US Department of Energy's Oak Ridge Reservation. The scrap yard was formerly used formore » aboveground storage of contaminated material (e.g., steel tanks, metal, glass, concrete, and miscellaneous industrial trash) from the Oak Ridge K-25 Site, Oak Ridge Y-12 Plant, and ORNL. The purposes of this cursory investigation were (1) to provide an updated contamination status of the site by locating and interpreting the presence, nature, and extent of surface radiological contamination and (2) to provide a basis for the formulation of interim corrective action to limit human exposures to radioactivity and minimize the potential for contaminant dispersion. 13 refs., 17 figs., 5 tabs.« less

  2. Changes in tar yields and cigarette design in samples of Chinese cigarettes, 2009 and 2012

    PubMed Central

    Schneller, Liane M.; Zwierzchowski, Benjamin A.; Caruso, Rosalie V.; Li, Qiang; Yuan, Jiang; Fong, Geoffrey T.; O'Connor, Richard J.

    2015-01-01

    BACKGROUND China is home to both the greatest number of smokers and the greatest number of smoking-related deaths. An active and growing market of cigarettes marketed as “light” or “low tar” may keep health-concerned smokers from quitting, wrongly believing that such brands are less harmful. OBJECTIVE This study sought to observe changes in cigarette design characteristics and reported tar, nicotine and carbon monoxide (TNCO) levels in a sample of cigarette brands obtained in seven Chinese cities from 2009 and 2012. METHODS Cigarettes were purchased and shipped to Roswell Park Cancer Institute, where 91 pairs of packs were selected for physical cigarette design characteristic testing and recording of TNCO values. Data analysis was conducted using SPSS, and was initially characterized using descriptive statistics, correlations and generalized estimating equations to observe changes in brand varieties over time. FINDINGS Reported TNCO values on packs saw mean tar, nicotine and CO levels decrease from 2009 to 2012 by 7.9%, 4.5% and 6.0%, respectively. Ventilation was the only cigarette design feature that significantly changed over time (p < 0.001), with an increase of 31.7%. Significant predictors of tar and CO yields overall were ventilation and per-cigarette tobacco weight, while for nicotine tobacco moisture was also an independent predictor of yield. CONCLUSION The use of ventilation to decrease TNCO emissions is misleading smokers to believe that they are smoking a “light/low” tar cigarette that is healthier, and is potentially forestalling the quitting behaviors that would begin to reduce the health burden of tobacco in China, and so should be prohibited. PMID:25352560

  3. Association of daily tar and nicotine intake with incident myocardial infarction: Results from the population-based MONICA/KORA Augsburg Cohort Study 1984 - 2002

    PubMed Central

    2011-01-01

    Background Cigarette smoking has been shown to be one of the most important risk factors for cardiovascular diseases. However, little is known about cumulative effects of daily tar and nicotine intake on the risk of incident myocardial infarction (MI) so far. To bridge this gap, we conducted an analysis in a large prospective study from Southern Germany investigating associations of daily tar and nicotine intake with an incident MI event. Methods The study was based on 4,099 men and 4,197 women participating in two population-based MONICA Augsburg surveys between 1984 and 1990 and followed up within the KORA framework until 2002. During a mean follow-up of 13.3 years, a number of 307 men and 80 women developed an incident MI event. Relative risks were calculated as hazard ratios (HRs) estimated by Cox proportional hazards models adjusted for cardiovascular risk factors. Results In the present study, male regular smokers consumed on average more cigarettes per day than female regular smokers (20 versus 15) and had a higher tar and nicotine intake per day. In men, the MI risk compared to never-smokers increased with higher tar intake: HRs were 2.24 (95% CI 1.40-3.56) for 1-129 mg/day, 2.12 (95% CI 1.37-3.29) for 130-259 mg/day and 3.01 (95% CI 2.08-4.36) for ≥ 260 mg/day. In women, the corresponding associations were comparable but more pronounced for high tar intake (HR 4.67, 95% CI 1.76-12.40). Similar associations were observed for nicotine intake. Conclusions The present study based on a large population-based sample adds important evidence of cumulative effects of tar and nicotine intake on the risk of incident MI. Even low or medium tar and nicotine intake revealed substantial risk increases as compared to never-smokers. Therefore, reduction of tar and nicotine contents in cigarettes cannot be seen as a suitable public health policy in preventing myocardial infarction. PMID:21542909

  4. Analysis of pure tar substances (polycyclic aromatic hydrocarbons) in the gas stream using ultraviolet visible (UV-Vis) spectroscopy and multivariate curve resolution (MCR).

    PubMed

    Weide, Tobias; Guschin, Viktor; Becker, Wolfgang; Koelle, Sabine; Maier, Simon; Seidelt, Stephan

    2015-01-01

    The analysis of tar, mostly characterized as polycyclic aromatic hydrocarbons (PAHs), describes a topic that has been researched for years. An online analysis of tar in the gas stream in particular is needed to characterize the tar conversion or formation in the biomass gasification process. The online analysis in the gas is carried out with ultraviolet-visible (UV-Vis) spectroscopy (190-720 nm). This online analysis is performed with a measuring cell developed by the Fraunhofer Institute for Chemical Technology (ICT). To this day, online tar measurements using UV-Vis spectroscopy have not been carried out in detail. Therefore, PAHs are analyzed as follows. The measurements are split into different steps. The first step to prove the online method is to vaporize single tar substances. These experiments show that a qualitative analysis of PAHs in the gas stream with the used measurement setup is possible. Furthermore, it is shown that the method provides very exact results, so that a differentiation of various PAHs is possible. The next step is to vaporize a PAH mixture. This step consists of vaporizing five pure substances almost simultaneously. The interpretation of the resulting data is made using a chemometric interpretation method, the multivariate curve resolution (MCR). The verification of the calculated results is the main aim of this experiment. It has been shown that the tar mixture can be analyzed qualitatively and quantitatively (in arbitrary units) in detail using the MCR. Finally it is the main goal of this paper to show the first steps in the applicability of the UV-Vis spectroscopy and the measurement setup on online tar analysis in view of characterizing the biomass gasification process. Due to that, the gasification plant (at the laboratory scale), developed and constructed by the Fraunhofer ICT, has been used to vaporize these substances. Using this gasification plant for the experiments enables the usage of the measurement setup also for the

  5. Temporal and spatial variability of aeolian sand transport: Implications for field measurements

    NASA Astrophysics Data System (ADS)

    Ellis, Jean T.; Sherman, Douglas J.; Farrell, Eugene J.; Li, Bailiang

    2012-01-01

    Horizontal variability is often cited as one source of disparity between observed and predicted rates of aeolian mass flux, but few studies have quantified the magnitude of this variability. Two field projects were conducted to evaluate meter-scale spatial and temporal in the saltation field. In Shoalhaven Heads, NSW, Australia a horizontal array of passive-style sand traps were deployed on a beach for 600 or 1200 s across a horizontal span of 0.80 m. In Jericoacoara, Brazil, traps spanning 4 m were deployed for 180 and 240 s. Five saltation sensors (miniphones) spaced 1 m apart were also deployed at Jericoacoara. Spatial variation in aeolian transport rates over small spatial and short temporal scales was substantial. The measured transport rates ( Q) obtained from the passive traps ranged from 0.70 to 32.63 g/m/s. When considering all traps, the coefficient of variation ( CoV) values ranged from 16.6% to 67.8%, and minimum and maximum range of variation coefficient ( RVC) values were 106.1% to 152.5% and 75.1% to 90.8%, respectively. The miniphone Q and CoV averaged 47.1% and 4.1% for the 1260 s data series, which was subsequently sub-sampled at 60-630 s intervals to simulate shorter deployment times. A statistically significant ( p < 0.002), inverselinear relationship was found between sample duration and CoV and between Q and CoV, the latter relationship also considering data from previous studies.

  6. Periodontal considerations for esthetics: edentulous ridge augmentation.

    PubMed

    Rosenberg, E S; Cutler, S A

    1993-01-01

    Edentulous ridge augmentation is a plastic surgical technique that is performed to improve patient esthetics when unsightly, deformed ridges exist. This article describes the etiology of ridge deformities and the many procedures that can be executed to achieve an esthetic, functional result. Historically, soft-tissue mucogingival techniques were described to augment collapsed ridges. Pedicle grafts, free soft-tissue grafts, and subepithelial connective tissue grafts are predictable forms of therapy. More recently, ridge augmentation techniques were developed that regenerate the lost periodontium. These include allografts, bioglasses, guided tissue regenerative procedures, and tissue expansion.

  7. Methotrexate iontophoresis versus coal tar ointment in palmoplantar psoriasis: A pilot study.

    PubMed

    Haseena, K; George, Sandhya; Riyaz, Najeeba; Sasidharanpillai, Sarita; Puthussery, Paul V

    2017-01-01

    Palmoplantar psoriasis is often disabling and refractory to conventional therapy. Systemic drugs are indicated in its severe form, but side effects are a concern with their use. Methotrexate is one such systemic drug which is effective and cheap. To reduce systemic toxicity, methotrexate has been tried topically but results have been inconsistent due to poor drug penetration into the skin by passive diffusion. Iontophoresis may enhance its absorption and efficacy. To evaluate the efficacy and safety of topical methotrexate iontophoresis in comparison with coal tar ointment in the treatment of palmoplantar psoriasis. Thirty-one patients with palmar and/or plantar psoriasis were selected for the study and 28 patients completed it. The side having more severe involvement was treated while the other palm/sole served as a control. Iontophoresis using methotrexate solution was carried out on the study palm/sole with the injectable preparation of methotrexate (50 mg/2 ml) once a week for the first 4 weeks and subsequently every two weeks, for a total of six sittings. The control palm/sole was treated with coal tar ointment on other days. Erythema, scaling, induration and fissuring scores were noted in both groups before and after treatment. Both study and control groups showed decreases in scores but the reduction was more in the study group, the difference being statistically significant. Drawbacks of our study include the small sample size and the lack of follow-up. The study and control arms were not exactly matched and the study was not blinded. Methotrexate iontophoresis was safe and more effective than coal tar ointmentin palmoplantarpsoriasis.

  8. Clear cutting (10-13th century) and deep stable economy (18-19th century) as responsible interventions for sand drifting and plaggic deposition in cultural landscapes on aeolian sands (SE-Netherlands).

    NASA Astrophysics Data System (ADS)

    van Mourik, Jan; Vera, Hein; Wallinga, Jakob

    2013-04-01

    The landscape in extensive areas in SE-Netherlands is underlain by coversand, deposited during the Late Glacial of the Weichselian. In the Preboreal, aeolian processes reduced soil formation. From the Preboreal to the Atlantic a deciduous climax forest developed. The geomorphology was a coversand landscape, composed of ridges (umbric podzols), coversand plains (gleyic podzols), coversand depressions (histic podzols) and small valleys (gleysols). The area was used by hunting people during the Late Paleolithic and Mesolithic. During the Bronze and Iron Ages the area was populated by people, living from forest grazing, shifting cultivation and trade. The natural deciduous forest gradually degraded into Calluna heath. The deforestation accelerated the soil acidification and affected the hydrology, which is reflected in drying out of ridges and wetting of depressions, promoting the development of histic podzols and even histosols. Aeolian erosion was during this period restricted to local, small scale sand drifting, related to natural hazards as forest fires and hurricanes and shifting cultivation. Sustainable crop productivity on chemically poor sandy substrates required application of organic fertilizers, composed of a mixture of organic litter and animal manure with a very low mineral compound, produced in shallow stables. At least since 1000 AD, heath management was regulated by a series of rules that aimed to protect the valuable heat lands against degradation. During the 11th, 12th and 13th centuries there was an increasing demand for wood and clear cutting transformed the majority of the forests in driftsand landscapes. The most important market was formed by the very wealthy Flemish cities. The exposed soil surface was subjected to wind erosion and sand drifting which endangered the Calluna heath, arable land and even farmhouses. As a consequence, umbric podzols, the natural climax soil under deciduous forests on coversand, degraded into larger scale driftsand

  9. Boundary Conditions for Aeolian Activity in North American Dune Fields

    NASA Astrophysics Data System (ADS)

    Halfen, A. F.; Lancaster, N.; Wolfe, S.

    2014-12-01

    Geomorphic and chronological data for dune fields are evaluated for three contrasting areas of North America: 1) the Prairie-Parkland-Boreal ecozones of the northern Great Plains in Canada; 2) the Central Great Plains of the USA; and 3) the deserts of southwestern USA and northern Mexico. Luminescence and radiocarbon ages for periods of dune accumulation and stability are compared with palaeoenvironment proxies to provide an assessment of the boundary conditions of dune system response to changes in sediment supply, availability, and mobility. Dune fields in the northern Great Plains were formed from sediment originating from glaciofluvial or glaciolacustrine sediments deposited during deglaciation 16-11 ka. Subsequent aeolian deposition occurred in Parkland and Prairie dune fields as a result of mid-Holocene (8-5 ka) and late-Holocene (< 3.5 ka) activity related to drought conditions that reworked pre-existing aeolian sands. In the Central Great Plains, dune fields are closely linked to fluvial sediment sources. Sediment supply was high during deglaciation of the Rocky Mountains and resulted in widespread dune construction 16-10 ka. Multiple periods of Holocene reactivation are recorded and reflect increased sediment availability during drought episodes. Dune fields in the southwestern deserts experienced periods of construction as a result of enhanced supply of sediment from fluvial and lacustrine sources during the period 11.8-8 ka and at multiple intervals during the late Holocene. Despite spatial and temporal gaps in chronometric data as a result of sampling biases, the record from North American dune fields indicates the strong influence of sediment supply on dune construction, with changes in sediment availability as a result of drought episodes resulting in dune field reactivation and reworking of pre-existing sediment.

  10. Relationship of respiratory symptoms and pulmonary function to tar, nicotine, and carbon monoxide yield of cigarettes

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

    Krzyzanowski, M.; Sherrill, D.L.; Paoletti, P.

    The data from consecutive surveys of the Tucson Epidemiologic Study (1981-1988) were used to evaluate the relationship in cigarette smokers of respiratory symptoms and pulmonary function to tar, nicotine, and carbon monoxide (CO) yields of the cigarette. There were 690 subjects who reported smoking regularly in at least one survey, over age 15. After adjustment for intensity and duration of smoking and for depth of inhalation, the risk of chronic phlegm, cough, and dyspnea were not related to the tar and nicotine yields. In 414 subjects with pulmonary function tested in at least one of the three surveys the spirometricmore » indices used were significantly related to the daily dose of tar, nicotine, and CO (product of the cigarette yield and daily number of cigarettes smoked). The effects were more pronounced for past than for current doses. However, the differentiation of pulmonary function due to various yields of cigarettes was small in comparison to the difference in pulmonary function between smokers and nonsmokers.« less

  11. Adsorption of nicotine and tar from the mainstream smoke of cigarettes by oxidized carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chen, Zhigang; Zhang, Lisha; Tang, Yiwen; Jia, Zhijie

    2006-02-01

    The adsorption of nicotine and tar from the mainstream smoke (MS) by the filter tips filled respectively with oxidized carbon nanotubes (O-CNTs), activated carbon and zeolite (NaY) has been investigated. O-CNTs show exceptional removal efficiency and their adsorption mechanism is investigated. Capillary condensation of some ingredients from MS in the inner hole of O-CNTs is observed and may be the primary reason for their superior removal efficiency. The effect of O-CNTs mass on the removal efficiencies is also studied and the results show that about 20-30 mg O-CNTs per cigarette can effectively remove most of nicotine and tar.

  12. MULTI-SCALE CONTROLS ON AND CONSEQUENCES OF AEOLIAN PROCESSES IN LANDSCAPE CHANGE IN ARID AND SEMI-ARID ENVIRONMENTS

    EPA Science Inventory

    This paper reviews the controls on aeolian processes and their consequences at plant-interspace, patch-landscape, and regional-global scales. Based on this review, we define the requirements for a cross-scale model of wind erosion in structurally complex arid and semiarid ecosyst...

  13. Meta-analysis of lung cancer in asphalt roofing and paving workers with external adjustment for confounding by coal tar

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

    Fayerweather, W.E.

    2007-07-01

    The study's objectives were to update Partanen's and Boffetta's 1994 meta-analysis of lung cancer among roofing and paving asphalt workers and explore the role of coal tar in explaining the statistical heterogeneity among these studies. Information retrieval strategies and eligibility criteria were defined for identifying the epidemiologic studies to be included in the analysis. The relative risk ratio (RR) for lung cancer was selected as the effect measure of interest. Coal tar bias factors were developed and used to externally adjust each eligible study's published RR for confounding by coal tar. The meta-Relative Risk (meta-RR) and its variance were estimatedmore » by general variance-based methods. Heterogeneity of the RRs was assessed by heterogeneity chi-square and I{sup 2} tests. The results from this update were similar to those in Partanen's and Boffetta's original meta-analysis. Although the meta-RRs for the roofers and the pavers were no longer statistically significantly different from one another, significant heterogeneity remained within each of the coal tar-adjusted sectors. Meta-analysis of non-experimental epidemiologic studies is subject to significant uncertainties as is externally correcting studies for confounding. Given these uncertainties, the specific quantitative estimates in this (or any similar) analysis must be viewed with caution. Nevertheless, this analysis provides support for the hypothesis proposed by several major reviewers that confounding by coal tar-related PAH exposures may explain most or all of the lung cancer risks found in the epidemiologic literature on asphalt roofing and paving workers.« less

  14. Effects on Ridge Segmentation, Magmatic Plumbing and Eruption Style Caused by Weak Hot-spot to Ridge Interaction: the Central Indian Ridge and Rodrigues Hot-spot Couplet.

    NASA Astrophysics Data System (ADS)

    Murton, B. J.; Parson, L. M.; Sauter, D.

    2001-12-01

    The intermediate spreading, Central Indian Ridge (CIR) forms a couplet with a weak hot-spot of which the Rodrigues archipelago is an expression. Recently collected bathymetry shows that despite having little in the way of a significant topographic swell, the hot-spot is associated with a change in offset sense across adjacent transforms of the CIR causing the ridge to draw nearer to the Rodrigues island system. The most proximal ridge segment of the CIR is over 20km long and comprises three non-transform bounded sub-segments. The most northerly sub-segment has a shallow (<3000m), narrow (<5km) and featureless flat rift valley. TOBI sidescan sonar imagery shows that the segment is host to a 15km-long, 5km-wide single sheet flow. Elsewhere in the segment the valley floor is characterised by long (>5km), narrow (<1km) ridges that often terminate in conical seamounts. These ridges are the loci of some of the acoustically freshest volcanic facies in the rift valley. Samples recovered from these ridges have similar petrology along strike. With increasing distance south along the CIR, the ridge segments are typically 500m deeper than to the north. Here they are about 75km long and bounded by transform offsets that are 50 km long. However, even in the deepest parts of these segments, where the axial floor is over 4000m deep at the ridge-transform-intersections, there is fresh lava and other evidence for abundant volcanic activity. Within these segments, the rift valley comprises mainly seamounts and hummocky volcanic features. We believe the westward stepping trend of the CIR towards the Rodrigues islands is a function of the hot spot. The elevated temperature and volatile content to the west reduces mantle viscosity which, combined with thinner and hence weaker lithosphere, influencec the loci of initial oceanic rifting and the relative position of the ridge axis. The unusually great length of the northern segment has a similar origin with the presence of thin and weak

  15. 48 CFR 1201.301-70 - Amendment of (TAR) 48 CFR chapter 12.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Amendment of (TAR) 48 CFR chapter 12. 1201.301-70 Section 1201.301-70 Federal Acquisition Regulations System DEPARTMENT OF TRANSPORTATION GENERAL FEDERAL ACQUISITION REGULATIONS SYSTEM Agency Acquisition Regulations 1201.301-70...

  16. 48 CFR 1201.301-70 - Amendment of (TAR) 48 CFR chapter 12.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 5 2012-10-01 2012-10-01 false Amendment of (TAR) 48 CFR chapter 12. 1201.301-70 Section 1201.301-70 Federal Acquisition Regulations System DEPARTMENT OF TRANSPORTATION GENERAL FEDERAL ACQUISITION REGULATIONS SYSTEM Agency Acquisition Regulations 1201.301-70...

  17. 48 CFR 1201.301-70 - Amendment of (TAR) 48 CFR chapter 12.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 5 2013-10-01 2013-10-01 false Amendment of (TAR) 48 CFR chapter 12. 1201.301-70 Section 1201.301-70 Federal Acquisition Regulations System DEPARTMENT OF TRANSPORTATION GENERAL FEDERAL ACQUISITION REGULATIONS SYSTEM Agency Acquisition Regulations 1201.301-70...

  18. 48 CFR 1201.301-70 - Amendment of (TAR) 48 CFR chapter 12.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Amendment of (TAR) 48 CFR chapter 12. 1201.301-70 Section 1201.301-70 Federal Acquisition Regulations System DEPARTMENT OF TRANSPORTATION GENERAL FEDERAL ACQUISITION REGULATIONS SYSTEM Agency Acquisition Regulations 1201.301-70...

  19. Carslberg Ridge and Mid-Atlantic Ridge: Slow-spreading Apparent Analogs

    NASA Astrophysics Data System (ADS)

    Rona, P. A.; Murton, B. J.; Bostrom, K.; Widenfalk, L.; Melson, W. G.; O'Hearn, T.; Cronan, D. S.; Jenkins, W. J.

    2005-12-01

    We compare morphology, tectonics, petrology, and hydrothermal activity of a known section of the Mid-Atlantic Ridge (MAR) between the Kane and Atlantis fracture zones (full multi-beam coverage 21N to 31N) to the lesser known Carlsberg Ridge (CR; limited multi-beam coverage plus satellite altimetry). The CR extends from the Owen Fracture Zone (10N) to the Vityaz Fracture Zone (5S) and spreads at half-rates (~1.2-1.8 cm/yr) similar to the MAR: 1) Morphology: Both ridges exhibit distinct segmentation (primarily sinistral) and axial valleys with high floor to crest relief (range 1122-1771 m). Average lengths of segments (CR: 70 km; MAR: 50 km) and crest-to crest width of the axial valley are greater on the CR (40 km) than MAR (23 km). Axial volcanic ridges form the neovolcanic zone on both ridges, typically 2.6 km wide and 213 m high on the CR. Average water depth near segment centers is greater on the MAR (3933 m) than the CR (3564 m). V-shaped patterns oblique to the spreading axis are present on both ridges. 2) Tectonics: Segments on each ridge are predominantly separated by short-offset (<30 km) non-transform discontinuities with longer transform faults generally spaced hundreds of kilometers apart. Bulls-eye Mantle Bouguer Lows (-30 to -50 mgal) are present at centers of spreading segments on both ridges. Metamorphic core complexes of lower crust and upper mantle are present on the MAR section (at fracture zones) and at least at one locality at 58.33E on the CR. 3) Petrology: MORB composition from our 20 stations along the CR fall into the MORB family, with no evidence of hotspot inputs (no excess K or Nb), or extreme fractionation, similar to the MAR section. REE and trace element patterns between 57E and 61E on the CR indicate increasing melt depletion to the northwest, while glasses exhibit a striking systematic increase in MgO (decrease in fractionation) to the northwest and attain among the most primitive composition of any ocean ridge adjacent to the Owen

  20. Ridge jumps associated with plume-ridge interaction: Mantle plume-lithosphere interaction and hotspot magmatism

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, E.; Ito, G.

    2007-12-01

    Interaction of mantle plumes and young lithosphere near mid-ocean ridges can lead to changes in spreading geometry by shifts of the ridge-axis toward the plume as seen at various hotspots, notably Iceland and the Galapagos. Previous work has shown that, with a sufficient magma flux, heating of the lithosphere by magmatism can significantly weaken the plate and, in some cases, could cause ridge jumps. Upwelling hot asthenosphere can also weaken the plate through thermal and mechanical thinning of the lithosphere. Using the finite element code CITCOM, we solve the equations of continuity, momentum and energy to examine deformation in near-ridge lithosphere associated with relatively hot upwelling asthenosphere and seafloor spreading. The mantle and lithosphere obey a non-Newtonian viscous rheology with plastic failure in the cold part of the lithosphere simulated by imposing an effective yield stress. Temperatures of the lithospheric thermal boundary region are initially given a square-root of age thermal profile while a hot patch is placed at the bottom to initiate a mantle-plume like upwelling. The effect of upwelling asthenosphere on ridge jumps is evaluated by varying three parameters: the plume excess temperature, the spreading rate and the distance of the plume from the ridge axis. Preliminary results show plume related thinning and weakening of the lithosphere over a wide area (100's of km's) with the rate of thinning increasing with the excess temperature of the plume. Initially, thinning occurs as the plume approaches the lithosphere and asthenospheric material is forced out of the way. As the plume material comes into contact with the lithosphere, thinning occurs through heating and mechanical removal of the thermal boundary layer. Thinning of the lithosphere is one of the primary factors in achieving a ridge jump. Another is large tensile stresses which can facilitate the initiation of rifting at this weakened location. Model stresses induced by the

  1. Discovery of a landscape-wide drape of late-glacial aeolian silt in the western Northern Calcareous Alps (Austria): First results and implications

    NASA Astrophysics Data System (ADS)

    Gild, Charlotte; Geitner, Clemens; Sanders, Diethard

    2018-01-01

    Aeolian deposits record palaeoenvironmental conditions and may coin soil properties. Whereas periglacial loess is extensively investigated for 200 years, the study of the intramontane wind-blown deposits of the Alps has just stuttered along. Herein, we describe a drape of polymictic siliciclastic silt interpreted as an aeolian deposit that veneers extensive areas in the western Northern Calcareous Alps (NCA), from kames terraces near valley floors up to last-glacial nunataks. The NCA - part of the Eastern Alps mountain range - consist mainly of Triassic carbonate rocks; these are overlain by deposits of the Last Glacial Maximum (LGM) and its deglacial-paraglacial aftermath (e.g., glacial tills, fluvio-lacustrine successions, alluvial fans, scree slopes) - and a regional drape of polymictic silt newly described herein. The drape is typically a few decimeters in thickness and slightly modified by soil formation; it consists mainly of well-sorted silt of quartz, feldspars, phyllosilicates (muscovite, chlorite, biotite), amphiboles and, rarely, calcite or dolomite. The drape is unrelated to the substrate: it overlies carbonate bedrock and - in lateral continuity - abandoned deposystems such as colluvial slopes of redeposited till, kames, alluvial fans, scree slopes, and rock avalanche deposits. The drape was spotted from near the present valley floors up to LGM nunataks, over a vertical range of some 2000 m; it is also present in catchments of the NCA that were not overridden by far-travelled ice streams and that lack metamorphic rock fragments. Two OSL quartz ages of the drape from two distinct locations (18.77 ± 1.55 ka; 17.81 ± 1.68 ka) fall into the early Alpine late-glacial interval shortly after the collapse of pleniglacial ice streams; this fits with geological and geomorphological evidence, respectively, that the drape should be of early late-glacial age, and that it accumulated during a specific interval of time. In the NCA, localized minor deposition of

  2. Oxygenated Interface on Biomass Burn Tar Balls Determined bySingle Particle Scanning Transmission X-ray Microscopy

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

    Tivanski, A.V.; Hopkins, R.J.; Tyliszczak, T.

    2007-06-21

    Carbonaceous particles originating from biomass burning canaccount for a large fraction of organic aerosols in a local environment.Presently, their composition, physical and chemical properties, as wellas their environmental effects are largely unknown. Tar balls, a distincttype of highly spherical carbonaceous biomass burn particles, have beenobserved in a number of field campaigns. The Yosemite AerosolCharacterization Study that took place in summer 2002 occurred during anactive fire season in the western United States; tar balls collectedduring this field campaign are described in this article. Scanningtransmission X-ray microscopy and near-edge X-ray absorption finestructure spectroscopy are used to determine the shape, structure, andsize-dependent chemicalmore » composition of ~;150 individual sphericalparticles ranging in size from 0.15 to 1.2mu m.The elemental compositionof tar balls is ~;55 percent atomic carbon and ~;45 percent atomicoxygen. Oxygen is present primarily as carboxylic carbonyls andoxygen-substituted alkyl (O-alkyl-C) functional groups, followed bymoderate amounts of ketonic carbonyls. The observed chemical composition,density, and carbon functional groups are distinctly different from sootor black carbon and more closely resemble high molecular weight polymerichumic-like substances, which could account for their reported opticalproperties. A detailed examination of the carboxylic carbonyl andO-alkyl-C functional groups as a function of particle size reveals a thinoxygenated interface layer. The high oxygen content, as well as thepresence of water-soluble carboxylic carbonyl groups, could account forthe reported hygroscopic properties of tar balls. The presence of theoxygenated layer is attributed to atmospheric processing of biomass burnparticles.« less

  3. Large-scale deformation associated with ridge subduction

    USGS Publications Warehouse

    Geist, E.L.; Fisher, M.A.; Scholl, D. W.

    1993-01-01

    Continuum models are used to investigate the large-scale deformation associated with the subduction of aseismic ridges. Formulated in the horizontal plane using thin viscous sheet theory, these models measure the horizontal transmission of stress through the arc lithosphere accompanying ridge subduction. Modelling was used to compare the Tonga arc and Louisville ridge collision with the New Hebrides arc and d'Entrecasteaux ridge collision, which have disparate arc-ridge intersection speeds but otherwise similar characteristics. Models of both systems indicate that diffuse deformation (low values of the effective stress-strain exponent n) are required to explain the observed deformation. -from Authors

  4. Streamflow, Water Quality, and Metal Loads from Chat Leachate and Mine Outflow into Tar Creek, Ottawa County, Oklahoma, 2005

    USGS Publications Warehouse

    Cope, Caleb C.; Becker, Mark F.; Andrews, William J.; DeHay, Kelli

    2008-01-01

    Picher mining district is an abandoned lead and zinc mining area located in Ottawa County, northeastern Oklahoma. During the first half of the 20th century, the area was a primary producer of lead and zinc in the United States. Large accumulations of mine tailings, locally referred to as chat, produce leachate containing cadmium, iron, lead, and zinc that enter drainages within the mining area. Metals also seep to local ground water and streams from unplugged shafts, vent holes, seeps, and abandoned mine dewatering wells. Streamflow measurements were made and water-quality samples were collected and analyzed from two locations in Picher mining district from August 16 to August 29 following a rain event beginning on August 14, 2005, to determine likely concentrations and loads of metals from tailings and mine outflows in the part of Picher mining district near Tar Creek. Locations selected for sampling included a tailings pile with an adjacent mill pond, referred to as the Western location, and a segment of Tar Creek from above the confluence with Lytle Creek to below Douthat bridge, referred to as Tar Creek Study Segment. Measured streamflow was less than 0.01 cubic foot per second at the Western location, with streamflow only being measurable at that site on August 16, 2005. Measured streamflows ranged from <0.01 to 2.62 cubic feet per second at Tar Creek Study Segment. One water-quality sample was collected from runoff at the Western location. Total metals concentrations in that sample were 95.3 micrograms per liter cadmium, 182 micrograms per liter iron, 170 micrograms per liter lead, 1,760 micrograms per liter zinc. Total mean metals concentrations in 29 water-quality samples collected from Tar Creek Study Segment from August 16-29, 2005, were 21.8 micrograms per liter cadmium, 7,924 micrograms per liter iron, 7.68 micrograms per liter lead, and 14,548 micrograms per liter zinc. No metals loading values were calculated for the Western location. Metals loading

  5. Non-Natural Linker Configuration in 2,6-Dipeptidyl-Anthraquinones Enhances the Inhibition of TAR RNA Binding/Annealing Activities by HIV-1 NC and Tat Proteins.

    PubMed

    Sosic, Alice; Saccone, Irene; Carraro, Caterina; Kenderdine, Thomas; Gamba, Elia; Caliendo, Giuseppe; Corvino, Angela; Di Vaio, Paola; Fiorino, Ferdinando; Magli, Elisa; Perissutti, Elisa; Santagada, Vincenzo; Severino, Beatrice; Spada, Valentina; Fabris, Dan; Frecentese, Francesco; Gatto, Barbara

    2018-06-12

    The HIV-1 nucleocapsid (NC) protein represents an excellent molecular target for the development of anti-retrovirals by virtue of its well-characterized chaperone activities, which play pivotal roles in essential steps of the viral life cycle. Our ongoing search for candidates able to impair NC binding/annealing activities led to the identification of peptidyl-anthraquinones as a promising class of nucleic acid ligands. Seeking to elucidate the inhibition determinants and increase the potency of this class of compounds, we have now explored the effects of chirality in the linker connecting the planar nucleus to the basic side chains. We show here that the non-natural linker configuration imparted unexpected TAR RNA targeting properties to the 2,6-peptidyl-anthraquinones and significantly enhanced their potency. Even if the new compounds were able to interact directly with the NC protein, they manifested a consistently higher affinity for the TAR RNA substrate and their TAR-binding properties mirrored their ability to interfere with NC-TAR interactions. Based on these findings, we propose that the viral Tat protein, sharing the same RNA substrate but acting in distinct phases of the viral life cycle, constitutes an additional druggable target for this class of peptidyl-anthraquinones. The inhibition of Tat-TAR interaction for the test compounds correlated again with their TAR-binding properties, while simultaneously failing to demonstrate any direct Tat-binding capabilities. These considerations highlighted the importance of TAR RNA in the elucidation of their inhibition mechanism, rather than direct protein inhibition. We have therefore identified anti-TAR compounds with dual in vitro inhibitory activity on different viral proteins, demonstrating that it is possible to develop multitarget compounds capable of interfering with processes mediated by the interactions of this essential RNA domain of HIV-1 genome with NC and Tat proteins.

  6. Relating sedimentary processes in the Bagnold Dunes to the development of crater basin aeolian stratification

    NASA Astrophysics Data System (ADS)

    Ewing, R. C.; Lapotre, M. G. A.; Lewis, K. W.; Day, M. D.; Stein, N.; Rubin, D. M.; Sullivan, R. J., Jr.; Banham, S.; Thomas, N. M.; Lamb, M. P.; Gupta, S.; Fischer, W. W.

    2017-12-01

    Wind-blown sand dunes are ubiquitous on the surface of Mars and are a recognized component of the martian stratigraphic record. Our current knowledge of the aeolian sedimentary processes that determine dune morphology, drive dune dynamics, and create aeolian cross-stratification are based upon orbital studies of ripple and dune morphodynamics, rover observations of stratification on Mars, Earth analogs, and experimental and theoretical studies of sand movement under martian conditions. Exploration of the Bagnold Dunes by the Curiosity Rover in Gale Crater, Mars provided the first opportunity to make in situ observations of martian dunes from the grain-to-dune scale. We used the suite of cameras on Curiosity, including Navigation Camera, Mast Camera, and Mars Hand Lens Imager. We measured grainsize and identified sedimentary processes similar to processes on terrestrial dunes, such as grainfall, grainflow, and impact ripples. Impact ripple grainsize had a median of 0.103 mm. Measurements of grainflow slopes indicate a relaxation angle of 29° and grainfall slopes indicate critical angles of at least 32°. Dissimilar to terrestrial dunes, large, meter-scale ripples form on all slopes of the dunes. The ripples form both sinuous and linear crestlines, have symmetric and asymmetric profiles, range in height between 12cm and 28cm, and host grainfall, grainflow, and impact ripples. The largest ripples are interpreted to integrate the annual wind cycle within the crater, whereas smaller large ripples and impact ripples form or reorient to shorter term wind cycling. Assessment of sedimentary processes in combination with dune type across the Bagnold Dunes shows that dune-field pattern development in response to a complex crater-basin wind regime dictates the distribution of geomorphic processes. From a stratigraphic perspective, zones of highest potential accumulation correlate with zones of wind convergence, which produce complex winds and dune field patterns thereby

  7. Volcanoclastics of the Walvis Ridge

    NASA Astrophysics Data System (ADS)

    Eroshenko, D. V.; Kharin, G. S.

    2018-03-01

    The paper generalizes the distribution of volcanoclastic material in the Cenozoic sedimentary cover of the Walvis Ridge, made on the basis of the DSDP (Deep Sea Drilling Projects) and ODP (Ocean Drilling Program). The cycles of volcanoclastic accumulation have been distinguished. It has been proved that the distribution of the material in the Paleogene primary reflects the dynamics of volcanism of the ridge itself. The sources of volcanoclastics have been determined. The possibility of the existence of Early Eocene submarine volcanoes in the central part of the ridge has been shown. The dynamics of volcanism of the ridge has been compared with the variability of major climatic markers in sediments, indicating the unity of volcanic processes in the region and processes that led to an increase in the index of 13C content in sediments and CO2 content in the atmosphere.

  8. Yields of tar, nicotine, and carbon monoxide in the sidestream smoke from 15 brands of Canadian cigarettes

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

    Rickert, W.S.; Robinson, J.C.; Collishaw, N.

    Sidestream smoke yields for 15 brands of cigarettes were determined under conditions where mainstream yields were approximately equal to those used for determining the values which appear on packages of Canadian cigarettes. Sidestream yields of tar, nicotine, and carbon monoxide were much higher than mainstream yields for all brands tested. The average sidestream-to-mainstream ratios for the 15 brands were 3.5, 6.6, and 6.8 for tar, nicotine, and carbon monoxide, respectively. The highest yields of sidestream were obtained from the brands with the lowest mainstream yields.

  9. The impact of steam and current density on carbon formation from biomass gasification tar on Ni/YSZ, and Ni/CGO solid oxide fuel cell anodes

    NASA Astrophysics Data System (ADS)

    Mermelstein, Joshua; Millan, Marcos; Brandon, Nigel

    The combination of solid oxide fuel cells (SOFCs) and biomass gasification has the potential to become an attractive technology for the production of clean renewable energy. However the impact of tars, formed during biomass gasification, on the performance and durability of SOFC anodes has not been well established experimentally. This paper reports an experimental study on the mitigation of carbon formation arising from the exposure of the commonly used Ni/YSZ (yttria stabilized zirconia) and Ni/CGO (gadolinium-doped ceria) SOFC anodes to biomass gasification tars. Carbon formation and cell degradation was reduced through means of steam reforming of the tar over the nickel anode, and partial oxidation of benzene model tar via the transport of oxygen ions to the anode while operating the fuel cell under load. Thermodynamic calculations suggest that a threshold current density of 365 mA cm -2 was required to suppress carbon formation in dry conditions, which was consistent with the results of experiments conducted in this study. The importance of both anode microstructure and composition towards carbon deposition was seen in the comparison of Ni/YSZ and Ni/CGO anodes exposed to the biomass gasification tar. Under steam concentrations greater than the thermodynamic threshold for carbon deposition, Ni/YSZ anodes still exhibited cell degradation, as shown by increased polarization resistances, and carbon formation was seen using SEM imaging. Ni/CGO anodes were found to be more resilient to carbon formation than Ni/YSZ anodes, and displayed increased performance after each subsequent exposure to tar, likely due to continued reforming of condensed tar on the anode.

  10. Base-flow characteristics of streams in the Valley and Ridge, Blue Ridge, and Piedmont physiographic provinces of Virginia

    USGS Publications Warehouse

    Nelms, D.L.; Harlow, G.E.; Hayes, Donald C.

    1995-01-01

    Growth within the Valley and Ridge, Blue Ridge, and Piedmont Physiographic Provinces of Virginia has focussed concern about allocation of surface-water flow and increased demands on the ground-water resources. The purpose of this report is to (1) describe the base-flow characteristics of streams, (2) identify regional differences in these flow characteristics, and (3) describe, if possible, the potential surface-water and ground-water yields of basins on the basis of the base-flow character- istics. Base-flow characteristics are presented for streams in the Valley and Ridge, Blue Ridge, and Piedmont Physiographic Provinces of Virginia. The provinces are separated into five regions: (1) Valley and Ridge, (2) Blue Ridge, (3) Piedmont/Blue Ridge transition, (4) Piedmont northern, and (5) Piedmont southern. Different flow statistics, which represent streamflows predominantly comprised of base flow, were determined for 217 continuous-record streamflow-gaging stations from historical mean daily discharge and for 192 partial-record streamflow-gaging stations by means of correlation of discharge measurements. Variability of base flow is represented by a duration ratio developed during this investigation. Effective recharge rates were also calculated. Median values for the different flow statistics range from 0.05 cubic foot per second per square mile for the 90-percent discharge on the streamflow-duration curve to 0.61 cubic foot per second per square mile for mean base flow. An excellent estimator of mean base flow for the Piedmont/Blue Ridge transition region and Piedmont southern region is the 50-percent discharge on the streamflow-duration curve, but tends to under- estimate mean base flow for the remaining regions. The base-flow variability index ranges from 0.07 to 2.27, with a median value of 0.55. Effective recharge rates range from 0.07 to 33.07 inches per year, with a median value of 8.32 inches per year. Differences in the base-flow characteristics exist between

  11. Integrated Results from Analysis of the Rocknest Aeolian Deposit by the Curiosity Rover

    NASA Technical Reports Server (NTRS)

    Leshin, L. A.; Grotzinger, J. P.; Blake, D. F.; Edgett, K. S.; Gellert, R.; Mahaffy, P. R.; Malin, M. C.; Wiens, R. C.; Treiman, A. H.; Ming, D. W.; hide

    2013-01-01

    The Mars Science Laboratory Curiosity rover spent 45 sols (from sol 56-101) at an area called Rocknest (Fig. 1), characterizing local geology and ingesting its aeolian fines into the analytical instruments CheMin and SAM for mineralogical and chemical analysis. Many abstracts at this meeting present the contextual information and detailed data on these first solid samples analyzed in detail by Curiosity at Rocknest. Here, we present an integrated view of the results from Rocknest - the general agreement from discussions among the entire MSL Science Team.

  12. Emergence and petrology of the Mendocino Ridge

    NASA Astrophysics Data System (ADS)

    Fisk, Martin R.; Duncan, Robert A.; Fox, Christopher G.; Witter, Jeffrey B.

    1993-11-01

    The Mendocino Fracture Zone, a 3,000-km-long transform fault, extends from the San Andreas Fault at Cape Mendocino, California due west into the central Pacific basin. The shallow crest of this fracture zone, known as the Mendocino Ridge, rises to within 1,100 m of the sea surface at 270 km west of the California Coast. Rounded basalt pebbles and cobbles, indicative of a beach environment, are the dominant lithology at two locations on the crest of Mendocino Ridge and a40Ar/39 Ar incremental heating age of 11.0 ± 1.0 million years was determined for one of the these cobbles. This basalt must have been erupted on the Gorda Ridge because the crust immediately to the south of the fracture zone is older than 27 Ma. This age also implies that the crest of Mendocino Ridge was at sea level and would have blocked Pacific Ocean eastern boundary currents and affected the climate of the North American continent at some time since the late Miocene. Basalts from the Mendocino Fracture Zone (MFZ) are FeTi basalts similar to those commonly found at intersections of mid-ocean ridges and fracture zones. These basalts are chemically distinct from the nearby Gorda Ridge but they could have been derived from the same mantle source as the Gorda Ridge basalts. The location of the 11 Ma basalt suggests that Mendocino Ridge was transferred from the Gorda Plate to the Pacific Plate and the southern end of Gorda Ridge was truncated by a northward jump in the transform fault of MFZ.

  13. Hydrothermal Activity Along the Central Indian Ridge: Ridges, Hotspots and Philately.

    NASA Astrophysics Data System (ADS)

    German, C. R.; Connelly, D. P.; Evans, A. J.; Murton, B. J.; Curewitz, D.; Okino, K.; Statham, P. J.; Parson, L. M.

    2001-12-01

    The global mid-ocean ridge crest extends 50-60,000km and the majority remains unexplored for hydrothermal activity. Even those areas which are reasonably familiar continue to spring surprises (e.g. the "Lost City" site found in late 2000). Within the confines of conceivable research budgets, therefore, choosing new areas for investigation and exploration demands an intelligent approach, beyond flicking through holiday brochures or identifying missing entries for the John Edmond Memorial Stamp Collection. With that caveat, the Southampton Oceanography Centre led a 10-week expedition to the Central Indian Ridge, earlier this year, based in and around Mauritius. During cruise CD127 (23 April-23 May) we conducted a systematic investigation of the ridge crest (seafloor and overlying water column) between 18 deg 16 min and 20 deg 49 min South. We chose this area to investigate the distribution of hydrothermal activity both close to, and away from, that section of the ridge crest which continues to reflect past influence of the migrating Rodrigues hot-spot. Our hypothesis was that the high incidence of hydrothermal activity we had located previously, near the Azores Triple Junction, may result from waning influence of the Azores Hot-Spot nearby and that similar effects might be found resulting from interaction of the CIR with the Rodrigues hot-spot. The primary scientific package we employed was the SOC's TOBI deep-tow sidescan vehicle, now up-graded with an extra Light Scattering Sensor string. In concert, this instrumentation allowed us to prospect for particle-laden hydrothermal plumes in the water column overlying the ridge-crest, in real-time, whilst simultaneously acquiring high-resolution sidescan images of the underlying seafloor. Using this approach, particle-rich anomalies were observed at 5 locations along ca. 300km of surveyed ridge-crest, including 4 sites all within the extended (hot-spot influenced) segment 15, which stretches from 18 deg 45 to 20 deg 14

  14. Dark and Bright Ridges on Europa

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This high-resolution image of Jupiter's moon Europa, taken by NASA's Galileo spacecraft camera, shows dark, relatively smooth region at the lower right hand corner of the image which may be a place where warm ice has welled up from below. The region is approximately 30 square kilometers in area. An isolated bright hill stands within it. The image also shows two prominent ridges which have different characteristics; youngest ridge runs from left to top right and is about 5 kilometers in width (about 3.1 miles). The ridge has two bright, raised rims and a central valley. The rims of the ridge are rough in texture. The inner and outer walls show bright and dark debris streaming downslope, some of it forming broad fans. This ridge overlies and therefore must be younger than a second ridge running from top to bottom on the left side of the image. This dark 2 km wide ridge is relatively flat, and has smaller-scale ridges and troughs along its length.

    North is to the top of the picture, and the sun illuminates the surface from the upper left. This image, centered at approximately 14 degrees south latitude and 194 degrees west longitude, covers an area approximately 15 kilometers by 20 kilometers (9 miles by 12 miles). The resolution is 26 meters (85 feet) per picture element. This image was taken on December 16, 1997 at a range of 1300 kilometers (800 miles) by Galileo's solid state imaging system.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

  15. Impacts of Vegetation and Development on the Morphology of Coastal Sand Dunes Using Modern Geospatial Techniques: Jockey's Ridge Case Study

    NASA Astrophysics Data System (ADS)

    Weaver, K.; Mitasova, H.; Overton, M.

    2011-12-01

    area of sand that once fed the dunes, limiting aeolian sand transport and migration of the dune system. Not only are vegetation and development increasing around the Jockey's Ridge State Park, but vegetation is increasing inside the park boundaries with the majority of growth along the windward side of the dune system, blocking sand from feeding the dunes. Vegetation growth is also found to increase in front of the dune field, recently causing the migration of the dune to slow down.

  16. Remedial Investigation Report on Chestnut Ridge Operable Unit 2 (Filled Coal Ash Pond/Upper McCoy Branch) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. Volume 1. Main Text

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

    Not Available

    1994-08-01

    This document is a report on the remedial investigation (RI) of Chestnut Ridge Operable Unit (OU) 2 at the Oak Ridge Y-12 Plant. Chestnut Ridge OU 2 consists of Upper McCoy Branch (UMB), the Filled Coal Ash Pond (FCAP), and the area surrounding the Sluice Channel formerly associated with coal ash disposal in the FCAP. Chestnut Ridge OU 2 is located within the U.S. Department of Energy`s (DOE`s) Oak Ridge Reservation in Anderson County, Tennessee, approximately 24 miles west of Knoxville. The pond is an 8.5-acre area on the southern slope of Chestnut Ridge, 0.5 mile south of the mainmore » Y-12 Plant and geographically separated from the Y-12 Plant by Chestnut Ridge. The elevation of the FCAP is {approximately} 950 ft above mean sea level (msl), and it is relatively flat and largely vegetated. Two small ponds are usually present at the northeast and northwest comers of the FCAP. The Sluice Channel Area extends {approximately}1000 ft from the northern margin of the FCAP to the crest of Chestnut Ridge, which has an elevation of {approximately}1100 ft above msl. The Sluice Channel Area is largely vegetated also. McCoy Branch runs from the top of Chestnut Ridge across the FCAP into Rogers Quarry and out of the quarry where it runs a short distance into Milton Hill Lake at McCoy Embayment, termed UMB. The portion south of Rogers Quarry, within Chestnut Ridge OU 4, is termed Lower McCoy Branch. The DOE Oak Ridge Y-12 Plant disposed of coal ash from its steam plant operations as a slurry that was discharged into an ash retention impoundment; this impoundment is the FCAP. The FCAP was built in 1955 to serve as a settling basin after coal ash slurried over Chestnut Ridge from the Y-12 Plant. The FCAP was constructed by building an earthen dam across the northern tributary of McCoy Branch. The dam was designed to hold 20 years of Y-12 steam plant ash. By July 1967, ash had filled up the impoundment storage behind the dam to within 4 ft of the top.« less

  17. Comprehensive integrated planning: A process for the Oak Ridge Reservation, Oak Ridge, Tennessee

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

    NONE

    1998-05-01

    The Oak Ridge Comprehensive Integrated Plan is intended to assist the US Department of Energy (DOE) and contractor personnel in implementing a comprehensive integrated planning process consistent with DOE Order 430.1, Life Cycle Asset Management and Oak Ridge Operations Order 430. DOE contractors are charged with developing and producing the Comprehensive Integrated Plan, which serves as a summary document, providing information from other planning efforts regarding vision statements, missions, contextual conditions, resources and facilities, decision processes, and stakeholder involvement. The Comprehensive Integrated Plan is a planning reference that identifies primary issues regarding major changes in land and facility use andmore » serves all programs and functions on-site as well as the Oak Ridge Operations Office and DOE Headquarters. The Oak Ridge Reservation is a valuable national resource and is managed on the basis of the principles of ecosystem management and sustainable development and how mission, economic, ecological, social, and cultural factors are used to guide land- and facility-use decisions. The long-term goals of the comprehensive integrated planning process, in priority order, are to support DOE critical missions and to stimulate the economy while maintaining a quality environment.« less

  18. Bilaterally cleft lip, limb defects, and haematological manifestations: Roberts syndrome versus TAR syndrome.

    PubMed

    Urban, M; Opitz, C; Bommer, C; Enders, H; Tinschert, S; Witkowski, R

    1998-09-23

    We report on a 13-year-old patient followed since birth. He is the only offspring of young, non-consanguineous German parents. His mother has an isolated left cleft of lip and a cleft palate. At birth, our patient presented with bilaterally cleft lip/cleft palate, phocomelia of upper limbs with normal hands, and mild symmetrical deficiencies of the long bones of the lower limbs. Haematological evaluation demonstrated a leukaemoid reaction during a urinary tract infection as well as intermittent thrombocytopenia and episodes of marked eosinophilia during the first two years of life. Intellectual development has been normal. Comparison with two similar cases from the literature suggests a non-random phenotypic overlap of Roberts syndrome (MIM 268300) and TAR syndrome (MIM 274000). Such clinical constellations may be key observations to understand the genetic relationship of Roberts syndrome and TAR syndrome in future phenotype-genotype correlations.

  19. Holocene climatic change, aeolian sedimentation and the nomadic Anthropocene in Eastern Tibet

    NASA Astrophysics Data System (ADS)

    Lehmkuhl, F.; Schlütz, F.

    2009-04-01

    Geomorphological and palynological studies from the Nianbaoyeze Shan in Eastern Tibet provides detailed information on the Holocene landscape and vegetation development of a mountain system located on the westernmost boundary of the modern forest belt. In addition, detailed sedimentological work was done on a section south of the Anyemachin Shan further west. Our study provides detailed information on the late glacial landscape and vegetation development of eastern Tibet. Based on a suite of geomorphological and palynological proxy data from the Nianbaoyeze Shan on the eastern margin of the Tibetan Plateau (33°N/101°E, 3300-4500 m asl) we reconstruct recent landscape dynamics as a function of climate change and the longevity of human influence. Study results constrain several major phases of aeolian sedimentation between 50 - 15 ka and various glacier advances during the Late Pleistocene, the Holocene and the Little Ice Age (LIA). Increased aeolian deposition was primarily associated with periods of more extensive glacial ice extent. Fluvial and alluvial sediment pulses also document an increase of erosion starting at about 4000 cal yr B.P. coinciding with cooling (Neoglacial) and a growing anthropo-zoogenic influence. Evidence for periglacial mass movements indicate that the late Holocene cooling started at around 2000 cal yr B.P. demonstrating increased surface activity under the combined effects of human influence and climate deterioration (LIA). In a section south of the Anyemachin about 150 km further west Holocene silt and paleosols development match to these results but showing higher Holocene aeolian activity. The Holocene vegetation history started with an open landscape dominated by pioneer shrubs along braided rivers (<10,600 - 9800 cal yr B.P.), followed by the spreading of conifers (Picea, Juniperus, Abies) and Betula-trees accompanied by a successive closing of the vegetation cover by Poaceae, Cyperaceae and herbs (9800 - 8300 cal yr B.P.). First

  20. Magmatic control along a strike-slip volcanic arc: The central Aeolian arc (Italy)

    NASA Astrophysics Data System (ADS)

    Ruch, J.; Vezzoli, L.; De Rosa, R.; Di Lorenzo, R.; Acocella, V.

    2016-02-01

    The regional stress field in volcanic areas may be overprinted by that produced by magmatic activity, promoting volcanism and faulting. In particular, in strike-slip settings, the definition of the relationships between the regional stress field and magmatic activity remains elusive. To better understand these relationships, we collected stratigraphic, volcanic, and structural field data along the strike-slip central Aeolian arc (Italy): here the islands of Lipari and Vulcano separate the extensional portion of the arc (to the east) from the contractional one (to the west). We collected >500 measurements of faults, extension fractures, and dikes at 40 sites. Most structures are NNE-SSW to NNW-SSE oriented, eastward dipping, and show almost pure dip-slip motion, consistent with an E-W extension direction, with minor dextral and sinistral shear. Our data highlight six eruptive periods during the last 55 ka, which allow considering both islands as a single magmatic system, in which tectonic and magmatic activities steadily migrated eastward and currently focus on a 10 km long × 2 km wide active segment. Faulting appears to mostly occur in temporal and spatial relation with magmatic events, supporting that most of the observable deformation derives from transient magmatic activity (shorter term, days to months), rather than from steady longer-term regional tectonics (102-104 years). More in general, the central Aeolian case shows how magmatic activity may affect the structure and evolution of volcanic arcs, overprinting any strike-slip motion with magma-induced extension at the surface.

  1. Does Graft Particle Type and Size Affect Ridge Dimensional Changes After Alveolar Ridge Split Procedure?

    PubMed

    Kheur, Mohit G; Kheur, Supriya; Lakha, Tabrez; Jambhekar, Shantanu; Le, Bach; Jain, Vinay

    2018-04-01

    The absence of an adequate volume of bone at implant sites requires augmentation procedures before the placement of implants. The aim of the present study was to assess the ridge width gain with the use of allografts and biphasic β-tricalcium phosphate with hydroxyapatite (alloplast) in ridge split procedures, when each were used in small (0.25 to 1 mm) and large (1 to 2 mm) particle sizes. A randomized controlled trial of 23 subjects with severe atrophy of the mandible in the horizontal dimension was conducted in a private institute. The patients underwent placement of 49 dental implants after a staged ridge split procedure. The patients were randomly allocated to alloplast and allograft groups (predictor variable). In each group, the patients were randomly assigned to either small graft particle or large graft particle size (predictor variable). The gain in ridge width (outcome variable) was assessed before implant placement. A 2-way analysis of variance test and the Student unpaired t test were used for evaluation of the ridge width gain between the allograft and alloplast groups (predictor variable). Differences were considered significant if P values were < .05. The sample included 23 patients (14 men and 9 women). The patients were randomly allocated to the alloplast (n = 11) or allograft (n = 12) group before the ridge split procedure. In each group, they were assigned to a small graft particle or large graft particle size (alloplast group, small particle in 5 and large particle size in 6 patients; allograft group, small particle in 6 and large particle size in 6). A statistically significant difference was observed between the 2 graft types. The average ridge width gain was significantly greater in the alloplast group (large, 4.40 ± 0.24 mm; small, 3.52 ± 0.59 mm) than in the allograft group (large, 3.82 ± 0.19 mm; small, 2.57 ± 0.16 mm). For both graft types (alloplast and allograft), the large particle size graft resulted in a

  2. Epoxy-borax-coal tar composition for a radiation protective, burn resistant drum liner and centrifugal casting method

    DOEpatents

    Taylor, Robert S.; Boyer, Norman W.

    1980-01-01

    A boron containing burn resistant, low level radiation protection material useful, for example, as a liner for radioactive waste disposal and storage, a component for neutron absorber, and a shield for a neutron source. The material is basically composed of Borax in the range of 25-50%, coal tar in the range of 25-37.5%, with the remainder being an epoxy resin mix. A preferred composition is 50% Borax, 25% coal tar and 25% epoxy resin. The material is not susceptible to burning and is about 1/5 the cost of existing radiation protection material utilized in similar applications.

  3. Epoxy-borax-coal tar composition for a radiation protective, burn resistant drum liner and centrifugal casting method

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

    Boyer, N.W.; Taylor, R.S.

    1980-10-28

    A boron containing burn resistant, low level radiation protection material useful, for example, as a liner for radioactive waste disposal and storage, a component for neutron absorber, and a shield for a neutron source. The material is basically composed of borax in the range of 25-50%, coal tar in the range of 25-37.5%, with the remainder being an epoxy resin mix. A preferred composition is 50% borax, 25% coal tar and 25% epoxy resin. The material is not susceptible to burning and is about 1/5 the cost of existing radiation protection material utilized in similar applications.

  4. Geographical Detector-Based Identification of the Impact of Major Determinants on Aeolian Desertification Risk

    PubMed Central

    Du, Ziqiang; Xu, Xiaoming; Zhang, Hong; Wu, Zhitao; Liu, Yong

    2016-01-01

    Arid and semi-arid areas in North China are facing the challenge of a rising aeolian desertification risk (ADR) due to the intertwined effects of complex natural processes and intensified anthropogenic activities. An accurate quantitative assessment of the relationship between ADR and its determinants is beneficial for understanding the driving mechanisms of aeolian desertification and for controlling future desertification. Previous studies have failed to quantify the relative role of determinants driving ADR and have been limited in assessing their interactive impacts. In this study, a spatial variance analysis-based geographical detector methodology is used to quantify the effects of geological, physical, and human factors on the occurrence of ADR in an area characterized by mountains and hills in northern China. It is found that soil type, precipitation, and wind velocity are the major determinants of ADR, which implies that geological and physical elements (e.g., soil attribute) and climatic factors (e.g., precipitation and wind velocity) rather than human activities have played a greater role in the incidence of ADR. Particularly, the results show that the interaction of various determinants causes significant non-linearly enhanced impacts on the ADR. The findings of our study will assist local inhabitants and policy makers in developing measures for wind prevention and sand control to mitigate the effects of desertification in the region. PMID:26987114

  5. Geographical Detector-Based Identification of the Impact of Major Determinants on Aeolian Desertification Risk.

    PubMed

    Du, Ziqiang; Xu, Xiaoming; Zhang, Hong; Wu, Zhitao; Liu, Yong

    2016-01-01

    Arid and semi-arid areas in North China are facing the challenge of a rising aeolian desertification risk (ADR) due to the intertwined effects of complex natural processes and intensified anthropogenic activities. An accurate quantitative assessment of the relationship between ADR and its determinants is beneficial for understanding the driving mechanisms of aeolian desertification and for controlling future desertification. Previous studies have failed to quantify the relative role of determinants driving ADR and have been limited in assessing their interactive impacts. In this study, a spatial variance analysis-based geographical detector methodology is used to quantify the effects of geological, physical, and human factors on the occurrence of ADR in an area characterized by mountains and hills in northern China. It is found that soil type, precipitation, and wind velocity are the major determinants of ADR, which implies that geological and physical elements (e.g., soil attribute) and climatic factors (e.g., precipitation and wind velocity) rather than human activities have played a greater role in the incidence of ADR. Particularly, the results show that the interaction of various determinants causes significant non-linearly enhanced impacts on the ADR. The findings of our study will assist local inhabitants and policy makers in developing measures for wind prevention and sand control to mitigate the effects of desertification in the region.

  6. Compressive strain in Lunae Planum-shortening across wrinkle ridges

    NASA Technical Reports Server (NTRS)

    Plescia, J. B.

    1991-01-01

    Wrinkle ridges have long been considered to be structural or structurally controlled features. Most, but not all, recent studies have converged on a model in which wrinkle ridges are structural features formed under compressive stress; the deformation being accommodated by faulting and folding. Given that wrinkle ridges are compressive tectonic features, an analysis of the associated shortening and strain provides important quantitative information about local and regional deformation. Lunae Planum is dominated by north-south trending ridges extending from Kasei Valles in the north to Valles Marineris in the south. To quantify the morphometric character, a photoclinometric study was undertaken for ridges on Lunae Planum using the Davis and Soderblom. More than 25 ridges were examined between long. 57 and 80 deg, lat. 5 to 25 deg N. For each ridge, several profiles were obtained along its length. Ridge width, total relief, and elevation offset were measured for each ridge. Analyses are given.

  7. Ridges and scarps in the equatorial belt of Mars

    USGS Publications Warehouse

    Lucchitta, B.K.; Klockenbrink, J.L.

    1981-01-01

    The morphology and distribution of ridges and scarps on Mars in the ?? 30?? latitude belt were investigated. Two distinct types of ridges were recognized. The first is long and linear, resembling mare ridges on the Moon; it occurs mostly in plains areas. The other is composed of short, anastomosing segments and occurs mostly in ancient cratered terrain and intervening plateaus. Where ridges are eroded, landscape configurations suggest that they are located along regional structures. The age of ridges is uncertain, but some are as young as the latest documented volcanic activity on Mars. The origins of ridges are probably diverse-they may result from wrinkling due to compression or from buckling due to settling over subsurface structures. The similar morphologic expressions of ridge types of various origins may be related to a similar deformation mechanism caused by two main factors: (1) most ridges are developed in thick layers of competent material and (2) ridges formed under stresses near a free surface. ?? 1981 D. Reidel Publishing Co.

  8. The role of aeolian sediment in the preservation of archaeological sites in the Colorado River corridor, Grand Canyon, Arizona: final report on research activities, 2003-2006

    USGS Publications Warehouse

    Draut, Amy E.; Rubin, David M.

    2007-01-01

    This report summarizes a three-year study of aeolian sedimentary processes in the Colorado River corridor, Grand Canyon, Arizona, and discusses the relevance of those processes to the preservation of archaeological sites. Findings are based upon detailed sedimentary and geomorphic investigations conducted in three areas of the river corridor, continuous measurements of wind, precipitation, and aeolian sediment transport at six locations for up to 26 months, short-term field study at 35 other sites, examination of historical aerial photographs, and review of data collected and analyzed by previous studies. Detailed results of this study, which involved collaboration with scientists at the Grand Canyon Monitoring and Research Center, National Park Service, Northern Arizona University, the Hopi Tribe, and GeoArch, Inc., have been published previously in topical USGS Open-File Reports (Draut and Rubin, 2005, 2006), a USGS Scientific Investigations Report (Draut and others, 2005), and will be discussed in two forthcoming journal articles. This report serves as an overview of the results and contains new conclusions regarding aeolian sedimentary processes in the Colorado River Ecosystem and their relevance to many archaeological sites.

  9. Structural determinants of HIV-1 nucleocapsid protein for cTAR DNA binding and destabilization, and correlation with inhibition of self-primed DNA synthesis.

    PubMed

    Beltz, Hervé; Clauss, Céline; Piémont, Etienne; Ficheux, Damien; Gorelick, Robert J; Roques, Bernard; Gabus, Caroline; Darlix, Jean-Luc; de Rocquigny, Hugues; Mély, Yves

    2005-05-20

    The nucleocapsid protein (NC) of human immunodeficiency virus type 1 (HIV-1) is formed of two highly conserved CCHC zinc fingers flanked by small basic domains. NC is required for the two obligatory strand transfers in viral DNA synthesis through its nucleic acid chaperoning properties. The first DNA strand transfer relies on NC's ability to bind and destabilize the secondary structure of complementary transactivation response region (cTAR) DNA, to inhibit self-priming, and to promote the annealing of cTAR to TAR RNA. To further investigate NC chaperone properties, our aim was to identify by fluorescence spectroscopy and gel electrophoresis, the NC structural determinants for cTAR binding and destabilization, and for the inhibition of self-primed DNA synthesis on a model system using a series of NC mutants and HIV-1 reverse transcriptase. NC destabilization and self-priming inhibition properties were found to be supported by the two fingers in their proper context and the basic (29)RAPRKKG(35) linker. The strict requirement of the native proximal finger suggests that its hydrophobic platform (Val13, Phe16, Thr24 and Ala25) is crucial for binding, destabilization and inhibition of self-priming. In contrast, only partial folding of the distal finger is required, probably for presenting the Trp37 residue in an appropriate orientation. Also, Trp37 and the hydrophobic residues of the proximal finger appear to be essential for the propagation of the melting from the cTAR ends up to the middle of the stem. Finally, both N-terminal and C-terminal basic domains contribute to cTAR binding but not to its destabilization.

  10. Geophysical Characteristics of the Australian-Antarctic Ridge

    NASA Astrophysics Data System (ADS)

    Kim, S. S.; Lin, J.; Park, S. H.; Choi, H.; Lee, S. M.

    2014-12-01

    Between 2011 and 2013, the Korea Polar Research Institute (KOPRI) conducted three consecutive geologic surveys at the little explored eastern ends of the Australian-Antarctic Ridge (AAR) to characterize the tectonics, geochemistry, and hydrothermal activity of this intermediate spreading system. Using the Korean icebreaker R/V Araon, the multi-disciplinary research team collected bathymetry, gravity, magnetics, and rock and water column samples. In addition, Miniature Autonomous Plume Recorders (MAPRs) were deployed at wax-core rock sampling sites to detect the presence of active hydrothermal vents. Here we present a detailed analysis of a 300-km-long supersegment of the AAR to quantify the spatial variations in ridge morphology and robust axial and off-axis volcanisms. The ridge axis morphology alternates between rift valleys and axial highs within relatively short ridge segments. To obtain a geological proxy for regional variations in magma supply, we calculated residual mantle Bouguer gravity anomalies (RMBA), gravity-derived crustal thickness, and residual topography for seven sub-segments. The results of the analyses revealed that the southern flank of the AAR is associated with shallower seafloor, more negative RMBA, thicker crust, and/or less dense mantle than the conjugate northern flank. Furthermore, this north-south asymmetry becomes more prominent toward the KR1 supersegment of the AAR. The axial topography of the KR1 supersegment exhibits a sharp transition from axial highs at the western end to rift valleys at the eastern end, with regions of axial highs being associated with more magma supply as indicated by more negative RMBA. We also compare and contrast the characteristics of the AAR supersegment with that of other ridges of intermediate spreading rates, including the Juan de Fuca Ridge, Galápagos Spreading Center, and Southeast Indian Ridge west of the Australian-Antarctic Discordance, to investigate the influence of ridge-hotspot interaction on

  11. 36 CFR 7.34 - Blue Ridge Parkway.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Blue Ridge Parkway. 7.34... REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.34 Blue Ridge Parkway. (a) Snowmobiles. After consideration... waters of the Blue Ridge Parkway is prohibited except on the waters of Price Lake. (2) Vessels using...

  12. 36 CFR 7.34 - Blue Ridge Parkway.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Blue Ridge Parkway. 7.34... REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.34 Blue Ridge Parkway. (a) Snowmobiles. After consideration... waters of the Blue Ridge Parkway is prohibited except on the waters of Price Lake. (2) Vessels using...

  13. 36 CFR 7.34 - Blue Ridge Parkway.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Blue Ridge Parkway. 7.34... REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.34 Blue Ridge Parkway. (a) Snowmobiles. After consideration... waters of the Blue Ridge Parkway is prohibited except on the waters of Price Lake. (2) Vessels using...

  14. The region preceding the C-terminal NWETF pentapeptide modulates baseline activity and aspartate inhibition of Escherichia coli Tar.

    PubMed

    Lai, Run-Zhi; Bormans, Arjan F; Draheim, Roger R; Wright, Gus A; Manson, Michael D

    2008-12-16

    The Tar chemoreceptor-CheA-CheW ternary complex of Escherichia coli is a transmembrane allosteric enzyme in which binding of ligands to the periplasmic domain modulates the activity of CheA kinase. Kinase activity is also affected by reversible methylation of four glutamyl residues in the cytoplasmic domain of the receptor. E. coli Tar contains 553 residues. Residues 549-553 comprise the NWETF pentapeptide that binds the CheR methyltransferase and CheB methylesterase. The crystal structure of the similar Tsr chemoreceptor predicts that residues 263-289 and 490-515 of Tar form the most membrane-proximal portion of the extended CD1-CD2 four-helix bundle of the cytoplasmic domain. The last methylation site, Glu-491, is in the C19 heptad, and the N22-19 and C22-19 heptads are present in all classes of bacterial transmembrane chemoreceptors. Residues 516-548 probably serve as a flexible tether for the NWETF pentapeptide. Here, we present a mutational analysis of residues 505-548. The more of this region that is deleted, the less sensitive Tar is to inhibition by aspartate. Tar deleted from residue 505 through the NWETF sequence stimulates CheA in vitro but is not inhibited by aspartate. Thus, interaction of the last two heptads (C21 and C22) of CD2 with the first two heptads (N22 and N21) of CD1 must be important for transmitting an inhibitory signal from the HAMP domain to the four-helix bundle. The R514A, K523A, R529A, R540A, and R542A substitutions, singly or together, increase the level of activation of CheA in vitro, whereas the R505A substitution decreases the level of CheA stimulation by 40% and lowers the aspartate K(i) 7-fold. The R505E substitution completely abolishes stimulation of CheA in vitro. Glu-505 may interact electrostatically with Asp-273 to destabilize the "on" signaling state by loosening the four-helix bundle.

  15. Downwind effects on an arid dunefield from an evolving urbanised area

    NASA Astrophysics Data System (ADS)

    Hernández-Calvento, L.; Jackson, D. W. T.; Medina, R.; Hernández-Cordero, A. I.; Cruz, N.; Requejo, S.

    2014-12-01

    The impacts of urbanised zones on aeolian dynamics are little understood, particularly within arid areas. This study examines the large-scale influence of a growing tourist resort in Gran Canaria Island, Spain, on the sedimentary dynamics of an arid dunefield. Direct downwind effects from the urban area on the dune field surface are modelled for pre-growth and post-growth phases of the urban development. The geomorphological changes observed in the area stretching from the shoreline to the inland transgressive dune field were documented through aerial photographic and LiDAR evidence. Impacts of the urban growth on airflow, as well as those induced by tourists in the upper beach zone (de-vegetation), are examined through analysis of topographic changes. These impacts on the system are shown to have been synergistic in driving the development of a composite dune ridge, formed by the coalescence of smaller dunes into a distinctive aeolian accumulation ridge.

  16. Coal-tar-based sealcoated pavement: a major PAH source to urban stream sediments.

    PubMed

    Witter, Amy E; Nguyen, Minh H; Baidar, Sunil; Sak, Peter B

    2014-02-01

    We used land-use analysis, PAH concentrations and assemblages, and multivariate statistics to identify sediment PAH sources in a small (~1303 km(2)) urbanizing watershed located in South-Central, Pennsylvania, USA. A geographic information system (GIS) was employed to quantify land-use features that may serve as PAH sources. Urban PAH concentrations were three times higher than rural levels, and were significantly and highly correlated with combined residential/commercial/industrial land use. Principal components analysis (PCA) was used to group sediments with similar PAH assemblages, and correlation analysis compared PAH sediment assemblages to common PAH sources. The strongest correlations were observed between rural sediments (n = 7) and coke-oven emissions sources (r = 0.69-0.78, n = 5), and between urban sediments (n = 22) and coal-tar-based sealcoat dust (r = 0.94, n = 47) suggesting that coal-tar-based sealcoat is an important urban PAH source in this watershed linked to residential and commercial/industrial land use. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Volcanism and hydrothermalism on a hotspot-influenced ridge: Comparing Reykjanes Peninsula and Reykjanes Ridge, Iceland

    NASA Astrophysics Data System (ADS)

    Pałgan, Dominik; Devey, Colin W.; Yeo, Isobel A.

    2017-12-01

    Current estimates indicate that the number of high-temperature vents (one of the primary pathways for the heat extraction from the Earth's mantle) - at least 1 per 100 km of axial length - scales with spreading rate and should scale with crustal thickness. But up to present, shallow ridge axes underlain by thick crust show anomalously low incidences of high-temperature activity. Here we compare the Reykjanes Ridge, an abnormally shallow ridge with thick crust and only one high-temperature vent known over 900 km axial length, to the adjacent subaerial Reykjanes Peninsula (RP), which is characterized by high-temperature geothermal sites confined to four volcanic systems transected by fissure swarms with young (Holocene) volcanic activity, multiple faults, cracks and fissures, and continuous seismic activity. New high-resolution bathymetry (gridded at 60 m) of the Reykjanes Ridge between 62°30‧N and 63°30‧N shows seven Axial Volcanic Ridges (AVR) that, based on their morphology, geometry and tectonic regime, are analogues for the volcanic systems and fissure swarms on land. We investigate in detail the volcano-tectonic features of all mapped AVRs and show that they do not fit with the previously suggested 4-stage evolution model for AVR construction. Instead, we suggest that AVR morphology reflects the robust or weak melt supply to the system and two (or more) eruption mechanisms may co-exist on one AVR (in contrast to 4-stage evolution model). Our interpretations indicate that, unlike on the Reykjanes Peninsula, faults on and around AVRs do not cluster in orientation domains but all are subparallel to the overall strike of AVRs (orthogonal to spreading direction). High abundance of seamounts shows that the region centered at 62°47‧N and 25°04‧W (between AVR-5 and -6) is volcanically robust while the highest fault density implies that AVR-1 and southern part of AVR-6 rather undergo period of melt starvation. Based on our observations and interpretations we

  18. PAHs underfoot: contaminated dust from coal-tar sealcoated pavement is widespread in the United States.

    PubMed

    Van Metre, Peter C; Mahler, Barbara J; Wilson, Jennifer T

    2009-01-01

    We reported in 2005 that runoff from parking lots treated with coal-tar-based sealcoat was a major source of polycyclic aromatic hydrocarbons (PAHs) to streams in Austin, Texas. Here we present new data from nine U.S. cities that show nationwide patterns in concentrations of PAHs associated with sealcoat. Dust was swept from parking lots in six cities in the central and eastern U.S., where coal-tar-based sealcoat dominates use, and three cities in the western U.S., where asphalt-based sealcoat dominates use. For six central and eastern cities, median SigmaPAH concentrations in dust from sealcoated and unsealcoated pavement are 2200 and 27 mg/kg, respectively. For three western cities, median SigmaPAH concentrations in dust from sealcoated and unsealcoated pavement are similar and very low (2.1 and 0.8 mg/kg, respectively). Lakes in the central and eastern cities where pavement was sampled have bottom sediments with higher PAH concentrations than do those in the western cities relative to degree of urbanization. Bottom-sediment PAH assemblages are similar to those of sealcoated pavement dust regionally, implicating coal-tar-based sealcoat as a PAH source to the central and eastern lakes. Concentrations of benzo[a]pyrene in dustfrom coal-tarsealcoated pavement and adjacent soils greatly exceed generic soil screening levels, suggesting that research on human-health risk is warranted.

  19. Coal-tar-based pavement sealcoat, polycyclic aromatic Hydrocarbons (PAHs), and environmental health

    USGS Publications Warehouse

    Mahler, B.J.; Van Metre, P.C.

    2011-01-01

    Studies by the U.S. Geological Survey (USGS) have identified coal-tar-based sealcoat-the black, viscous liquid sprayed or painted on asphalt pavement such as parking lots-as a major source of polycyclic aromatic hydrocarbon (PAH) contamination in urban areas for large parts of the Nation. Several PAHs are suspected human carcinogens and are toxic to aquatic life.

  20. Inhibition of HIV Replication by Cyclic and Hairpin PNAs Targeting the HIV-1 TAR RNA Loop

    PubMed Central

    Upert, Gregory; Di Giorgio, Audrey; Upadhyay, Alok; Manvar, Dinesh; Pandey, Nootan; Pandey, Virendra N.; Patino, Nadia

    2012-01-01

    Human immunodeficiency virus-1 (HIV-1) replication and gene expression entails specific interaction of the viral protein Tat with its transactivation responsive element (TAR), to form a highly stable stem-bulge-loop structure. Previously, we described triphenylphosphonium (TPP) cation-based vectors that efficiently deliver nucleotide analogs (PNAs) into the cytoplasm of cells. In particular, we showed that the TPP conjugate of a linear 16-mer PNA targeting the apical stem-loop region of TAR impedes Tat-mediated transactivation of the HIV-1 LTR in vitro and also in cell culture systems. In this communication, we conjugated TPP to cyclic and hairpin PNAs targeting the loop region of HIV-1 TAR and evaluated their antiviral efficacy in a cell culture system. We found that TPP-cyclic PNAs containing only 8 residues, showed higher antiviral potency compared to hairpin PNAs of 12 or 16 residues. We further noted that the TPP-conjugates of the 8-mer cyclic PNA as well as the 16-mer linear PNA displayed similar antiviral efficacy. However, cyclic PNAs were shown to be highly specific to their target sequences. This communication emphasizes on the importance of small constrained cyclic PNAs over both linear and hairpin structures for targeting biologically relevant RNA hairpins. PMID:23029603

  1. Ridges on Europa

    NASA Image and Video Library

    1997-12-18

    This view of Jupiter's moon Europa shows a portion of the surface that has been highly disrupted by fractures and ridges. This picture covers an area about 238 kilometers (150 miles) wide by 225 kilometers (140 miles), or about the distance between Los Angeles and San Diego. Symmetric ridges in the dark bands suggest that the surface crust was separated and filled with darker material, somewhat analogous to spreading centers in the ocean basins of Earth. Although some impact craters are visible, their general absence indicates a youthful surface. The youngest ridges, such as the two features that cross the center of the picture, have central fractures, aligned knobs, and irregular dark patches. These and other features could indicate cryovolcanism, or processes related to eruption of ice and gases. This picture, centered at 16 degrees south latitude, 196 degrees west longitude, was taken at a distance of 40,973 kilometers (25,290 mi) on November 6, 1996 by the Galileo spacecraft solid state imaging television camera onboard the Galileo spacecraft during its third orbit around Jupiter. http://photojournal.jpl.nasa.gov/catalog/PIA00518

  2. Declines in a ground-dwelling arthropod community during an invasion by Sahara mustard (Brassica tournefortii) in aeolian sand habitats

    Treesearch

    Heather L. Hulton VanTassel; Anne M. Hansen; Cameron W. Barrows; Quresh Latif; Margaret W. Simon; Kurt E. Anderson

    2014-01-01

    Sahara Mustard (Brassica tournefortii; hereafter mustard), an exotic plant species, has invaded habitats throughout the arid southwestern United States. Mustard has reached high densities across aeolian sand habitats of southwestern deserts, including five distinct sand habitats in the eastern Coachella Valley, California. We examined trends in ground-dwelling...

  3. Petrological systematics of mid-ocean ridge basalts: Constraints on melt generation beneath ocean ridges

    NASA Astrophysics Data System (ADS)

    Langmuir, Charles H.; Klein, Emily M.; Plank, Terry

    Mid-ocean ridge basalts (MORB) are a consequence of pressure-release melting beneath ocean ridges, and contain much information concerning melt formation, melt migration and heterogeneity within the upper mantle. MORB major element chemical systematics can be divided into global and local aspects, once they have been corrected for low pressure fractionation and interlaboratory biases. Regional average compositions for ridges unaffected by hot spots ("normal" ridges) can be used to define the global correlations among normalized Na2O, FeO, TiO2 and SiO2 contents, CaO/Al2O3 ratios, axial depth and crustal thickness. Back-arc basins show similar correlations, but are offset to lower FeO and TiO2 contents. Some hot spots, such as the Azores and Galapagos, disrupt the systematics of nearby ridges and have the opposite relationships between FeO, Na2O and depth over distances of 1000 km. Local variations in basalt chemistry from slow- and fast-spreading ridges are distinct from one another. On slow-spreading ridges, correlations among the elements cross the global vector of variability at a high angle. On the fast-spreading East Pacific Rise (EPR), correlations among the elements are distinct from both global and slow-spreading compositional vectors, and involve two components of variation. Spreading rate does not control the global correlations, but influences the standard deviations of axial depth, crustal thickness, and MgO contents of basalts. Global correlations are not found in very incompatible trace elements, even for samples far from hot spots. Moderately compatible trace elements for normal ridges, however, correlate with the major elements. Trace element systematics are significantly different for the EPR and the mid-Atlantic Ridge (MAR). Normal portions of the MAR are very depleted in REE, with little variability; hot spots cause large long wavelength variations in REE abundances. Normal EPR basalts are significantly more enriched than MAR basalts from normal

  4. The response of source-bordering aeolian dunefields to sediment-supply changes 1: Effects of wind variability and river-valley morphodynamics

    USGS Publications Warehouse

    Sankey, Joel B.; Kasprak, Alan; Caster, Joshua; East, Amy; Fairley, Helen C.

    2018-01-01

    Source-bordering dunefields (SBDs), which are primarily built and maintained with river-derived sediment, are found in many large river valleys and are currently impacted by changes in sediment supply due to climate change, land use changes, and river regulation. Despite their importance, a physically based, applied approach for quantifying the response of SBDs to changes in sediment supply does not exist. To address this knowledge gap, here we develop an approach for quantifying the geomorphic responses to sediment-supply alteration based on the interpretation of dunefield morphodynamics from geomorphic change detection and wind characteristics. We use the approach to test hypotheses about the response of individual dunefields to variability in sediment supply at three SBDs along the Colorado River in Grand Canyon, Arizona, USA during the 11 years between 2002 and 2013 when several river floods rebuilt some river sandbars and channel margin deposits that serve as sediment source areas for the SBDs. We demonstrate that resupply of fluvially sourced aeolian sediment occurred at one of the SBDs, but not at the other two, and attribute this differential response to site-specific variability in geomorphology, wind, and sediment source areas. The approach we present is applied in a companion study to shorter time periods with high-resolution topographic data that bracket individual floods in order to infer the resupply of fluvially sourced aeolian sediment to SBDs by managed river flows. Such an applied methodology could also be useful for measuring sediment connectivity and anthropogenic alterations of connectivity in other coupled fluvial-aeolian environments.

  5. The response of source-bordering aeolian dunefields to sediment-supply changes 1: Effects of wind variability and river-valley morphodynamics

    NASA Astrophysics Data System (ADS)

    Sankey, Joel B.; Kasprak, Alan; Caster, Joshua; East, Amy E.; Fairley, Helen C.

    2018-06-01

    Source-bordering dunefields (SBDs), which are primarily built and maintained with river-derived sediment, are found in many large river valleys and are currently impacted by changes in sediment supply due to climate change, land use changes, and river regulation. Despite their importance, a physically based, applied approach for quantifying the response of SBDs to changes in sediment supply does not exist. To address this knowledge gap, here we develop an approach for quantifying the geomorphic responses to sediment-supply alteration based on the interpretation of dunefield morphodynamics from geomorphic change detection and wind characteristics. We use the approach to test hypotheses about the response of individual dunefields to variability in sediment supply at three SBDs along the Colorado River in Grand Canyon, Arizona, USA during the 11 years between 2002 and 2013 when several river floods rebuilt some river sandbars and channel margin deposits that serve as sediment source areas for the SBDs. We demonstrate that resupply of fluvially sourced aeolian sediment occurred at one of the SBDs, but not at the other two, and attribute this differential response to site-specific variability in geomorphology, wind, and sediment source areas. The approach we present is applied in a companion study to shorter time periods with high-resolution topographic data that bracket individual floods in order to infer the resupply of fluvially sourced aeolian sediment to SBDs by managed river flows. Such an applied methodology could also be useful for measuring sediment connectivity and anthropogenic alterations of connectivity in other coupled fluvial-aeolian environments.

  6. How Fast Do Europa's Ridges Grow?

    NASA Astrophysics Data System (ADS)

    Melosh, H. J.; Turtle, E. P.; Freed, A. M.

    2017-11-01

    We demonstrate with our incremental wedging model of ridge formation that ridges must grow in 5000 years or less to prevent their material flowing down an underlying warm ice channel. This conclusion holds for other models as well.

  7. Mantle plume capture, anchoring and outflow during ridge interaction

    NASA Astrophysics Data System (ADS)

    Gibson, S. A.; Richards, M. A.; Geist, D.

    2015-12-01

    Geochemical and geophysical studies have shown that >40% of the world's mantle plumes are currently interacting with the global ridge system and such interactions may continue for up to 180 Myr[1]. At sites of plume-ridge interaction up to 1400 km of the spreading centre is influenced by dispersed plume material but there are few constraints on how and where the ridge-ward transfer of deep-sourced material occurs, and also how it is sustained over long time intervals. Galápagos is an archetypal example of an off-axis plume and sheds important light on these mechanisms. The Galápagos plume stem is located ~200 km south of the spreading axis and its head influences 1000 km of the ridge. Nevertheless, the site of enriched basalts, greatest crustal thickness and elevated topography on the ridge, together with active volcanism in the archipelago, correlate with a narrow zone (~150 km) of low-velocity, high-temperature mantle that connects the plume stem and ridge at depths of ~100 km[2]. The enriched ridge basalts contain a greater amount of partially-dehydrated, recycled oceanic crust than basalts elsewhere on the spreading axis, or indeed basalts erupted in the region between the plume stem and ridge. The presence of these relatively volatile-rich ridge basalts requires flow of plume material below the peridotite solidus (i.e.>80 km). We propose a 2-stage model for the development and sustainment of a confined zone of deep ridge-ward plume flow. This involves initial on-axis capture and establishment of a sub-ridge channel of plume flow. Subsequent anchoring of the plume stem to a contact point on the ridge during axis migration results in confined ridge-ward flow of plume material via a deep network of melt channels embedded in the normal spreading and advection of the plume head[2]. Importantly, sub-ridge flow is maintained. The physical parameters and styles of mantle flow we have defined for Galápagos are less-well known at other sites of plume-ridge

  8. Aeolian Sediment Trapping Efficiencies of Sparse Vegetation and its Ecohydrological Consequences in Drylands

    NASA Astrophysics Data System (ADS)

    Gonzales, H. B.; Ravi, S.; Li, J. J.; Sankey, J. B.

    2016-12-01

    Hydrological and aeolian processes control the redistribution of soil and nutrients in arid and semi arid environments thereby contributing to the formation of heterogeneous patchy landscapes with nutrient-rich resource islands surrounded by nutrient depleted bare soil patches. The differential trapping of soil particles by vegetation canopies may result in textural changes beneath the vegetation, which, in turn, can alter the hydrological processes such as infiltration and runoff. We conducted infiltration experiments and soil grain size analysis of several shrub (Larrea tridentate) and grass (Bouteloua eriopoda) microsites and in a heterogeneous landscape in the Chihuahuan desert (New Mexico, USA). Our results indicate heterogeneity in soil texture and infiltration patterns under grass and shrub microsites. We assessed the trapping effectiveness of vegetation canopies using a novel computational fluid dynamics (CFD) approach. An open-source software (OpenFOAM) was used to validate the data gathered from particle size distribution (PSD) analysis of soil within the shrub and grass microsites and their porosities (91% for shrub and 68% for grass) determined using terrestrial LiDAR surveys. Three-dimensional architectures of the shrub and grass were created using an open-source computer-aided design (CAD) software (Blender). The readily available solvers within the OpenFOAM architecture were modified to test the validity and optimize input parameters in assessing trapping efficiencies of sparse vegetation against aeolian sediment flux. The results from the numerical simulations explained the observed textual changes under grass and shrub canopies and highlighted the role of sediment trapping by canopies in structuring patch-scale hydrological processes.

  9. DIANA-TarBase v7.0: indexing more than half a million experimentally supported miRNA:mRNA interactions.

    PubMed

    Vlachos, Ioannis S; Paraskevopoulou, Maria D; Karagkouni, Dimitra; Georgakilas, Georgios; Vergoulis, Thanasis; Kanellos, Ilias; Anastasopoulos, Ioannis-Laertis; Maniou, Sofia; Karathanou, Konstantina; Kalfakakou, Despina; Fevgas, Athanasios; Dalamagas, Theodore; Hatzigeorgiou, Artemis G

    2015-01-01

    microRNAs (miRNAs) are short non-coding RNA species, which act as potent gene expression regulators. Accurate identification of miRNA targets is crucial to understanding their function. Currently, hundreds of thousands of miRNA:gene interactions have been experimentally identified. However, this wealth of information is fragmented and hidden in thousands of manuscripts and raw next-generation sequencing data sets. DIANA-TarBase was initially released in 2006 and it was the first database aiming to catalog published experimentally validated miRNA:gene interactions. DIANA-TarBase v7.0 (http://www.microrna.gr/tarbase) aims to provide for the first time hundreds of thousands of high-quality manually curated experimentally validated miRNA:gene interactions, enhanced with detailed meta-data. DIANA-TarBase v7.0 enables users to easily identify positive or negative experimental results, the utilized experimental methodology, experimental conditions including cell/tissue type and treatment. The new interface provides also advanced information ranging from the binding site location, as identified experimentally as well as in silico, to the primer sequences used for cloning experiments. More than half a million miRNA:gene interactions have been curated from published experiments on 356 different cell types from 24 species, corresponding to 9- to 250-fold more entries than any other relevant database. DIANA-TarBase v7.0 is freely available. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

  10. First X-Ray Diffraction Results from Mars Science Laboratory: Mineralogy of Rocknest Aeolian Bedform at Gale Crater

    NASA Technical Reports Server (NTRS)

    Bish, D. L.; Blake, D. F.; Vaniman, D. T.; Chipera, S. J.; Sarrazin, P.; Morris, R. V.; Ming, D. W.; Treiman, A. H.; Downs, R. T.; Morrison, S. M.; hide

    2013-01-01

    Numerous orbital and landed observations of the martian surface suggest a reasonably uniform martian soil composition, likely as a result of global aeolian mixing [1, 2]. Chemical data for martian soils are abundant [e.g., 2, 3], and phase information has been provided by lander thermal emission and Moessbauer spectroscopic measurements [3, 4, 5, 6]. However, until now no X-ray diffraction (XRD) data were available for martian soil nor has XRD ever been used on another body apart from Earth. XRD is generally considered the most definitive method for determining the crystalline phases in solid samples, and it is the method of choice for determining mineralogy. CheMin s first XRD analysis on Mars coincided with the 100th anniversary of the discovery of X-ray diffraction by von Laue. Curiosity delivered scooped samples of loose, unconsolidated material ("soil") acquired from an aeolian bedform at the Rocknest locality to instruments in the body of the rover (the laboratory). Imaging shows that the soil has a range of particle sizes, of 1-2 mm and smaller, presumably representing contributions from global, regional, and local sources.

  11. Natural gamma-radiation in the Aeolian volcanic arc.

    PubMed

    Chiozzi, P; Pasquale, V; Verdoya, M; Minato, S

    2001-11-01

    Pulse-height distributions of gamma-rays, obtained with a field NaI(Tl) scintillation spectrometer in numerous sites of the Lipari and Vulcano islands (Aeolian volcanic arc, Italy), were measured to determine the U, Th and K concentrations of the bedrock and the relative values of the air absorbed dose rate. U is spatially related to both Th and K and the Th/U ratio is on average 3.1-3.5. The magmatic evolution is reflected by the concentration of the three radioelements, as they are more abundant within the more felsic units of the volcanic series. The higher values of U (15.7-20.0 ppm) coincide with higher Th (48.3-65.9 ppm) and K (4.9-6.1%) concentrations associated with rhyolitic rocks of the third cycle (< 50 ky). The air absorbed dose rate varies from 20 to 470 nGy h(-1). The highest values (> 350 nGy h(-1)) are observed on outcrops of rhyolitic obsidian lava flows. The cosmic-ray contribution is also evaluated to estimate the total background radiation dose rate.

  12. Stress history and geotechnical properties of sediment from the Cape Fear Diapir, Blake Ridge Diapir, and Blake Ridge

    USGS Publications Warehouse

    Winters, W.J.

    2000-01-01

    Geotechnical properties of sediment from Ocean Drilling Program Leg 164 are presented as: (1) normalized shipboard strength ratios from the Cape Fear Diapir, the Blake Ridge Diapir, and the Blake Ridge; and (2) Atterberg limit, vane shear strength, pocket-penetrometer strength, and constant-rate-of-strain consolidation results from Hole 995A, located on the Blake Ridge. This study was conducted to understand the stress history in a region characterized by high sedimentation rates and the presence of gas hydrates. Collectively, the results indicate that sediment from the Blake Ridge exhibits significant underconsolidated behavior, except near the seafloor. At least 10 m of additional overburden was removed by erosion or mass wasting at Hole 993A on the Cape Fear Diapir, compared to nearby sites.

  13. On the frequency response of a Wenglor particle-counting system for aeolian transport measurements

    NASA Astrophysics Data System (ADS)

    Bauer, Bernard O.; Davidson-Arnott, Robin G. D.; Hilton, Michael J.; Fraser, Douglas

    2018-06-01

    A commonly deployed particle-counting system for aeolian saltation flux, consisting of a Wenglor fork sensor and an Onset Hobo Pulse Input Adapter linked to an Onset Hobo Energy Logger Pro data logger, was tested for frequency response. The Wenglor fork sensor is an optical gate device that has very fast switching capacity that can accommodate the time of flight of saltating sand particles through the sensing volume with the exception of very fine sand or silt and very quickly moving particles. The Pulse Input Adapter, in contrast, imposes limitations on the frequency response of the system. The manufacturer of the pulse adapter specifies an upper limit of 120 Hz, although bench tests with an electronic pulse generator indicate that the frequency response of the Pulse Input Adapter, in isolation, is excellent up to 3000 Hz, with only small error (less than 1.6%) due to under-counting during data transfer intervals. A mechanical test of the integrated system (fork sensor, pulse input adapter, and data logger) demonstrates excellent performance up to about 700 Hz (less than 2% error), but significant under-counting above 1000 Hz for unknown reasons. This specific particle-counting system therefore has a frequency response that is well suited for investigation of the dynamics of aeolian saltation as typically encountered in most field conditions on coastal beaches with the exception of extreme wind events and very small particle sizes.

  14. Sedimentology and palaeontology of upper Karoo aeolian strata (Early Jurassic) in the Tuli Basin, South Africa

    NASA Astrophysics Data System (ADS)

    Bordy, Emese M.; Catuneanu, Octavian

    2002-08-01

    The Karoo Supergroup in the Tuli Basin (South Africa) consists of a sedimentary sequence composed of four stratigraphic units, namely the Basal, Middle and Upper units, and Clarens Formation. The units were deposited in continental settings from approximately Late Carboniferous to Middle Jurassic. This paper focuses on the Clarens Formation, which was examined in terms of sedimentary facies and palaeo-environments based on evidence provided by primary sedimentary structures, palaeo-flow measurements and palaeontological findings. Two main facies associations have been identified: (i) massive and large-scale planar cross-bedded sandstones of aeolian origin; and (ii) horizontally and cross-stratified sandstones of fluvial origin. Most of the sandstone lithofacies of the Clarens Formation were generated as transverse aeolian dunes produced by northwesterly winds in a relatively wet erg milieu. Direct evidence of aquatic subenvironments comes from local small ephemeral stream deposits, whereas palaeontological data provide indirect evidence. Fossils of the Clarens Formation include petrified logs of Agathoxylon sp. wood type and several trace fossils which were produced by insects and vertebrates. The upper part of the Clarens Formation lacks both direct and indirect evidence of aquatic conditions, and this suggests aridification that led to the dominance of dry sand sea conditions.

  15. Wrinkle Ridges and Young Fresh Crater

    NASA Image and Video Library

    2002-06-04

    This NASA Mars Odyssey image is of the ridged plains of Lunae Planum in the northern hemisphere of Mars. Wrinkle ridges, a very common landform on Mars, Mercury, Venus, and the Moon, are found mostly along the eastern side of the image.

  16. Lack of effect of menthol level and type on smokers' estimated mouth level exposures to tar and nicotine and perceived sensory characteristics of cigarette smoke.

    PubMed

    Ashley, Madeleine; Dixon, Mike; Sisodiya, Ajit; Prasad, Krishna

    2012-08-01

    Menthol can reduce sensory irritation and it has been hypothesised that this could result in smokers of mentholated cigarettes taking larger puffs and deeper post-puff inhalations thereby obtaining higher exposures to smoke constituents than smokers of non-mentholated cigarettes. The aim of our study was to use part-filter analysis methodology to assess the effects of cigarette menthol loading on regular and occasional smokers of mentholated cigarettes. We measured mouth level exposure to tar and nicotine and investigated the effects of mentholation on smokers' sensory perceptions such as cooling and irritation. Test cigarettes were produced containing no menthol and different loadings of synthetic and natural l-menthol at 1 and 4mg ISO tar yields. A target of 100 smokers of menthol cigarettes and 100 smokers who predominantly smoked non-menthol cigarettes from both 1 and 4mg ISO tar yield categories were recruited in Poland and Japan. Each subject was required to smoke the test cigarette types of their usual ISO tar yield. There were positive relationships between menthol loading and the perceived 'strength of menthol taste' and 'cooling' effect. However, we did not see marked menthol-induced reductions in perceived irritation or menthol-induced increases in mouth level exposure to tar and nicotine. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Observations of sea ice ridging in the Weddell Sea

    NASA Astrophysics Data System (ADS)

    Granberg, Hardy B.; Leppaäranta, Matti

    1999-11-01

    Sea ice surface topography data were obtained by helicopter-borne laser profiling during the First Finnish Antarctic Expedition (FINNARP-89). The measurements were made near the ice margin at about 73°S, 27°W in the eastern Weddell Sea on December 31, 1989, and January 1, 1990. Five transects, ranging in length from 127 to 163 km and covering a total length of 724 km, are analyzed. With a lower cutoff of 0.91 m the overall ridge frequency was 8.4 ridges/km and the average ridge height was 1.32 m. The spatial variations in ridging were large; for 36 individual 20-km segments the frequencies were 2-16 ridges/km and the mean heights were 1.16-1.56 m. The frequencies and mean heights were weakly correlated. The distributions of the ridge heights followed the exponential distribution; the spacings did not pass tests for either the exponential or the lognormal distribution, but the latter was much closer. In the 20-km segments the areally averaged thickness of ridged ice was 0.51±0.28 m, ranging from 0.10 to 1.15 m. The observed ridge size and frequency are greater than those known for the Ross Sea. Compared with the central Arctic, the Weddell Sea ridging frequencies are similar but the ridge heights are smaller, possibly as a result of differences in snow accumulation.

  18. Aeolian vibration control of overhead electrical transmission line conductors

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

    Sireteanu, T.; Migdalovici, M.; Videa, E.

    The paper presents a mathematical model and an analytical procedure to control the wind induced vibration of a single conductor such that the dynamic strain about the suspension clamp is kept within the imposed safety limits. The method is based on the energy balance principle which takes into account the wind energy input, the energy dissipated by the conductor self-damping properties and by the Stockbridge dampers which are frequently used for the aeolian vibration control. The damping characteristics of the Stockbridge dampers are expressed in terms of their mechanical impedance determined experimentally on a vibration exciter. The method can bemore » used to establish whether or not it is necessary to equip the conductor by Stockbridge dampers, which type of damper is more suitable for a given conductor, span length and EDS (every day stress), the necessary number of dampers as well as their optimum spacing on the conductor.« less

  19. Aeolian abrasion on Venus: Preliminary results from the Venus simulator

    NASA Technical Reports Server (NTRS)

    Marshall, J. R.; Greeley, Ronald; Tucker, D. W.; Pollack, J. B.

    1987-01-01

    The role of atmospheric pressure on aeolian abrasion was examined in the Venus Simulator with a constant temperature of 737 K. Both the rock target and the impactor were fine-grained basalt. The impactor was a 3 mm diameter angular particle chosen to represent a size of material that is entrainable by the dense Venusian atmosphere and potentially abrasive by virtue of its mass. It was projected at the target 10 to the 5 power times at a velocity of 0.7 m/s. The impactor showed a weight loss of approximately 1.2 x 10 to the -9 power gm per impact with the attrition occurring only at the edges. Results from scanning electron microscope analysis, profilometry, and weight measurement are summarized. It is concluded that particles can incur abrasion at Venusian temperatures even with low impact velocities expected for Venus.

  20. Improved Digitization of Lunar Mare Ridges with LROC Derived Products

    NASA Astrophysics Data System (ADS)

    Crowell, J. M.; Robinson, M. S.; Watters, T. R.; Bowman-Cisneros, E.; Enns, A. C.; Lawrence, S.

    2011-12-01

    Lunar wrinkle ridges (mare ridges) are positive-relief structures formed from compressional stress in basin-filling flood basalt deposits [1]. Previous workers have measured wrinkle ridge orientations and lengths to investigate their spatial distribution and infer basin-localized stress fields [2,3]. Although these plots include the most prominent mare ridges and their general trends, they may not have fully captured all of the ridges, particularly the smaller-scale ridges. Using Lunar Reconnaissance Orbiter Wide Angle Camera (WAC) global mosaics and derived topography (100m pixel scale) [4], we systematically remapped wrinkle ridges in Mare Serenitatis. By comparing two WAC mosaics with different lighting geometry, and shaded relief maps made from a WAC digital elevation model (DEM) [5], we observed that some ridge segments and some smaller ridges are not visible in previous structure maps [2,3]. In the past, mapping efforts were limited by a fixed Sun direction [6,7]. For systematic mapping we created three shaded relief maps from the WAC DEM with solar azimuth angles of 0°, 45°, and 90°, and a fourth map was created by combining the three shaded reliefs into one, using a simple averaging scheme. Along with the original WAC mosaic and the WAC DEM, these four datasets were imported into ArcGIS, and the mare ridges of Imbrium, Serenitatis, and Tranquillitatis were digitized from each of the six maps. Since the mare ridges are often divided into many ridge segments [8], each major component was digitized separately, as opposed to the ridge as a whole. This strategy enhanced our ability to analyze the lengths, orientations, and abundances of these ridges. After the initial mapping was completed, the six products were viewed together to identify and resolve discrepancies in order to produce a final wrinkle ridge map. Comparing this new mare ridge map with past lunar tectonic maps, we found that many mare ridges were not recorded in the previous works. It was noted