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Sample records for suppress fugitive dust

  1. Wind barriers suppress fugitive dust and soil-derived airborne particles in arid regions

    Energy Technology Data Exchange (ETDEWEB)

    Grantz, D.A.; Vaughn, D.L. [Univ. of California, Parlier, CA (United States). Kearney Agricultural Center; Farber, R.J. [SoCal Edison, Rosemead, CA (United States). Environmental Research Div.; Kim, B. [South Coast Air Quality Management District, Diamond Bar, CA (United States); Ashbaugh, L. [Univ. of California, Davis, CA (United States). Crocker Nuclear Lab.; Van Curen, T. [California Air Resources Board, Sacramento, CA (United States); Campbell, R. [Antelope Valley Resources Conservation District, Lancaster, CA (United States)

    1998-07-01

    Areas of abandoned agricultural land in the Antelope Valley, western Mojave (high) desert of California have proven in the previous studies to be recalcitrant to conventional tillage and revegetation strategies designed to suppress wind erosion of soil and transport of sediment and fugitive dust. These areas represented a continuing source of drifting sand and of coarse and respirable suspended particulate matter. The traditional techniques failed because furrows collapsed and the water holding capacity of the overburden was too low to support seed germination and transplant survival. In this study a variety of wind barriers were evaluated for suppression of sediment transport. Airborne particles were measured with an array of coarse particle samplers at heights of 0.2, 1.0, and 2.0 m above the soil surface. Discrete artificial wind barriers, consisting of widely spaced roughness elements were effective in suppressing fugitive emissions. Wind fences established along the leeward edge of an area of blowing sand, perpendicular to the prevailing wind, significantly decreased fugitive emissions. Control was greatest and precision of the measurements was highest under high wind conditions. These techniques provide rapid and effective suppression of fugitive emissions of soil-derived particles under conditions that resist conventional tillage and revegetation techniques. A simple, indirect procedure for determining local wind velocity erosion thresholds requiring only sampling of wind run and suspended particulate mass compared favorably with direct measurement of saltation as a function of wind velocity.

  2. Study on reinforcement of soil for suppressing fugitive dust by bio-cementitious material

    Science.gov (United States)

    Zhan, Qiwei; Qian, Chunxiang

    2017-06-01

    Microbial-induced reinforcement of soil, as a new green and environmental-friendly method, is being paid extensive attention to in that it has low cost, simple operation and rapid effects. In this research, reinforcement of soil for suppressing fugitive dust by bio-cementitious material was investigated. Soil cemented by bio-cementitious material had superior mechanical properties, such as hardness, compressive strength, microstructure, wind-erosion resistance, rainfall-erosion resistance and freeze-thaw resistance. The average hardness of sandy soil, floury soil and clay soil is 18.9 º, 25.2 º and 26.1 º, while average compressive strength of samples is 0.43 MPa, 0.54 MPa and 0.69 MPa, respectively; meanwhile, the average calcite content of samples is 6.85 %, 6.09 %, and 5.96 %, respectively. Compared with the original sandy soil, floury soil and clay soil, the porosity decreases by 38.5 %, 33.7 % and 29.2 %. When wind speed is 12 m/s, the mass loss of sandy soil, floury soil and clay soil cemented by bio-cementitious material are all less than 30 g/(m2·h). After three cycles of rainfall erosion of 2.5 mm/h, the mass loss are less than 25 g/(m2·h) and the compressive strength residual ratio are more than 98.0 %. Under 25 cycles of freeze-thaw, the mass loss ratio are less than 3.0 %.

  3. Wind tunnel tests of biodegradable fugitive dust suppressants being considered to reduce soil erosion by wind at radioactive waste construction sites

    International Nuclear Information System (INIS)

    Ligotke, M.W.; Dennis, G.W.; Bushaw, L.L.

    1993-10-01

    Wind tunnel tests were performed of three fugitive dust control agents derived from potato and sugar beet products. These materials are being considered for use as dust suppressants to reduce the potential for transport of radioactive materials by wind from radioactive waste construction and remediation sites. Soil and dust control agent type, solution concentrations, application quantities, aging (or drying) conditions, surface disturbance, and wind and saltating sand eolian erosive stresses were selected and controlled to simulate application and exposure of excavated soil surfaces in the field. A description of the tests, results, conclusions, and recommendations are presented in this report. The results of this study indicate that all three dust control agents can protect exposed soil surfaces from extreme eolian stresses. It is also clear that the interaction and performance of each agent with various soil types may differ dramatically. Thus, soils similar to that received from ML should be best protected by high concentration (∼2.5%) solutions of potato starch at low water application levels (∼1 to 2 L/m 2 ). Because the effectiveness of PS on this soil type is degraded after a moderate amount of simulated rainfall, other options or additives should be considered if surfaces are to be protected for long intervals or during periods of intermittent rainfall and hot, windy conditions. On the other hand, XDCA should be considered when excavating sandy soils. It should be noted, however, that because the Hanford soil test results are based on a small number of tests, it would be prudent to perform additional tests prior to selecting a fugitive dust control agent for use at the Hanford Site. While fermented potato waste was not the best fixative used on either soil, it did perform reasonably well on both soil types (better than XDCA on Idaho soil and better than PS on Hanford soil)

  4. Wind tunnel tests of biodegradable fugitive dust suppressants being considered to reduce soil erosion by wind at radioactive waste construction sites

    Energy Technology Data Exchange (ETDEWEB)

    Ligotke, M.W.; Dennis, G.W.; Bushaw, L.L.

    1993-10-01

    Wind tunnel tests were performed of three fugitive dust control agents derived from potato and sugar beet products. These materials are being considered for use as dust suppressants to reduce the potential for transport of radioactive materials by wind from radioactive waste construction and remediation sites. Soil and dust control agent type, solution concentrations, application quantities, aging (or drying) conditions, surface disturbance, and wind and saltating sand eolian erosive stresses were selected and controlled to simulate application and exposure of excavated soil surfaces in the field. A description of the tests, results, conclusions, and recommendations are presented in this report. The results of this study indicate that all three dust control agents can protect exposed soil surfaces from extreme eolian stresses. It is also clear that the interaction and performance of each agent with various soil types may differ dramatically. Thus, soils similar to that received from ML should be best protected by high concentration ({approximately}2.5%) solutions of potato starch at low water application levels ({approximately}1 to 2 L/m{sup 2}). Because the effectiveness of PS on this soil type is degraded after a moderate amount of simulated rainfall, other options or additives should be considered if surfaces are to be protected for long intervals or during periods of intermittent rainfall and hot, windy conditions. On the other hand, XDCA should be considered when excavating sandy soils. It should be noted, however, that because the Hanford soil test results are based on a small number of tests, it would be prudent to perform additional tests prior to selecting a fugitive dust control agent for use at the Hanford Site. While fermented potato waste was not the best fixative used on either soil, it did perform reasonably well on both soil types (better than XDCA on Idaho soil and better than PS on Hanford soil).

  5. Characterizing and Quantifying Emissions and Transport of Fugitive Dust Emissions Due to Department of Defense Activities

    Science.gov (United States)

    2015-09-19

    hematite. They suggest that this veneer of fine particles are removed, and thus enhance the dust concentration, through abrasion processes between the...FINAL REPORT Characterizing and Quantifying Emissions and Transport of Fugitive Dust Emissions Due to Department of Defense Activities SERDP...Fugitive Dust Emissions Due 5a. CONTRACT NUMBER Fugitive Dust Emissions Due to Department of Defense Activities 5b

  6. Review of fugitive dust control for uranium mill tailings

    International Nuclear Information System (INIS)

    Li, C.T.; Elmore, M.R.; Hartley, J.N.

    1983-01-01

    An immediate concern associated with the disposal of uranium mill tailings is that wind erosion of the tailings from an impoundment area will subsequently deposit tailings on surrounding areas. Pacific Northwest Laboratory (PNL), under contract to the U.S. Nuclear Regulatory Commission, is investigating the current technology for fugitive dust control. Different methods of fugitive dust control, including chemical, physical, and vegetative, have been used or tested on mill tailings piles. This report presents the results of a literature review and discussions with manufacturers and users of available stabilization materials and techniques

  7. Review of fugitive dust control for uranium mill tailings

    Energy Technology Data Exchange (ETDEWEB)

    Li, C.T.; Elmore, M.R.; Hartley, J.N.

    1983-01-01

    An immediate concern associated with the disposal of uranium mill tailings is that wind erosion of the tailings from an impoundment area will subsequently deposit tailings on surrounding areas. Pacific Northwest Laboratory (PNL), under contract to the U.S. Nuclear Regulatory Commission, is investigating the current technology for fugitive dust control. Different methods of fugitive dust control, including chemical, physical, and vegetative, have been used or tested on mill tailings piles. This report presents the results of a literature review and discussions with manufacturers and users of available stabilization materials and techniques.

  8. Fugitive dust control experiments using directed airflow in dumping operations

    International Nuclear Information System (INIS)

    Winberg, M.R.; Menkhaus, D.E.; Thompson, D.N.; Wixom, V.E.

    1992-07-01

    Experiments were conducted to evaluate the degree of dust control for using directed airflow in a funnel during dumping operations. Retrieved buried transuranic waste or overburden soils are expected to require focusing the retrieved material into a transporter box with a funnel and control of transuranic-contaminated dust at the funnel is mandatory. In these experiments, the Idaho National Engineering Laboratory soil was dumped into a full-scale funnel (capable of focusing waste into a 4 x 4 x 8 ft box) that was specially equipped with a directed airflow into the funnel. The degree of dust control was determined by comparing collected dust on filters in high volume samplers (strategically located) for a baseline case with no airflow to cases with airflow. Tests involving airflow into the funnel spanned a range of airflows at the opening between 15--100 linear feet per minute. The basic result is that the directed airflow concept is adequate to control dust spread during dumping

  9. Fugitive Dust Emissions: Development of a Real-time Monitor

    Science.gov (United States)

    2011-10-01

    pulverization and abrasion of surface materials by application of mechanical force through implements ( wheels , blades, tracks, etc.) and entrainment of dust...speed, mean vehicle weight, mean number of wheels , and number of days with detectable precipitation, to determine annual FD emissions for each vehicle... omnidirectional sampling, while an elliptical funnel section shape is used to ensure that the sampled air is transported with minimal recirculation

  10. Fugitive dust mitigation for PM{sub 10} attainment in the western Mojave Desert: Recommendations on revegetation

    Energy Technology Data Exchange (ETDEWEB)

    Grantz, D.A.; Vaughn, D.L. [Univ. of California, Riverside, CA (United States)]|[Kearney Agricultural Center, Parlier, CA (United States); Roberts, E. [RES Environmental Inc., Colton, CA (United States)] [and others

    1997-12-31

    Methods to suppress fugitive dust and associated violations of federal PM{sub 10} standards in the western Mojave Desert, following removal of native vegetation by tillage or overgrazing, have been under investigation by a multi-agency task force for several years. Interim recommendations are now possible for this area of high winds, low rainfall, and mostly arable soil with patchy blowing sand. There can be no guarantee of success in any revegetation program in the desert, but the greatest probability of success in this area can be attained by using the native shrub Atriplex canescens, whether direct seeded or transplanted. No additional nitrogen should be added, and excess nitrogen should be removed if possible, perhaps by a preliminary cropping of barley. This will itself stabilize the soil surface in the short term. Young plants should be protected from herbivory and the harsh elements by using plastic cones. Irrigation is helpful if available. In areas located near native populations of rabbitbrush annual plant cover should be burned but no tillage or other soil disturbance should be imposed, as this facilitates invasion of annual species, including russian thistle, and prevents establishment of rabbitbrush. In sandy areas, seeding with Indian ricegrass may be more effective than with A. canescens. For immediate, short-term, mitigation of blowing dust, furrowing alone and installation of windfences may be effective. Rainfall exhibits high annual variability in arid regions. Absence of fugitive dust emissions in rainy periods, associated with ground cover by annual vegetation, is unlikely to survive several years of low, but normal, rainfall. It is precisely during those periods when rainfall is adequate that long-term revegetation with shrubs has the best chance of success.

  11. Fugitive dust control experiments using soil fixatives on vehicle traffic surfaces

    International Nuclear Information System (INIS)

    Winberg, M.R.; Wixom, V.E.

    1992-08-01

    This report presents the results of engineering scale dust control experiments using soil fixative for contamination control during handling of transuranic waste. These experiments focused on controlling dust during retrieval operations of buried waste where waste and soil are intimately mixed. Sources of dust generation during retrieval operations include digging, dumping, and vehicle traffic. Because contaminants are expected to attach to soil particles and move with the generated dust, control of the dust spread may be the key to contamination control. Dust control techniques examined in these experiments include the use of soil fixatives to control generation of fugitive dusts during vehicle traffic operations. Previous experiments conducted in FY 1990 included testing of the soil fixative, ENTAC. These experiments showed that ENTAC was effective in controlling dust generation but had several undesirable properties such as slow cure times and clogged the pumps and application nozzles. Therefore, other products would have to be evaluated to find a suitable candidate. As a result, two soil fixatives were tested in these present experiments, COHEREX-PM, an asphalt emulsion product manufactured by Witco Corporation and FLAMBINDER, a calcium lignosulfonate product manufactured by Flambeau Corporation. The results of the experiments include product performance and recommended application methods for application in a field deployable contamination control unit to be built in FY 1993

  12. Soil sample collection and analysis for the Fugitive Dust Characterization Study

    Science.gov (United States)

    Ashbaugh, Lowell L.; Carvacho, Omar F.; Brown, Michael S.; Chow, Judith C.; Watson, John G.; Magliano, Karen C.

    A unique set of soil samples was collected as part of the Fugitive Dust Characterization Study. The study was carried out to establish whether or not source profiles could be constructed using novel analytical methods that could distinguish soil dust sources from each other. The soil sources sampled included fields planted in cotton, almond, tomato, grape, and safflower, dairy and feedlot facilities, paved and unpaved roads (both urban and rural), an agricultural staging area, disturbed land with salt buildup, and construction areas where the topsoil had been removed. The samples were collected using a systematic procedure designed to reduce sampling bias, and were stored frozen to preserve possible organic signatures. For this paper the samples were characterized by particle size (percent sand, silt, and clay), dry silt content (used in EPA-recommended fugitive dust emission factors), carbon and nitrogen content, and potential to emit both PM 10 and PM 2.5. These are not the "novel analytical methods" referred to above; rather, it was the basic characterization of the samples to use in comparing analytical methods by other scientists contracted to the California Air Resources Board. The purpose of this paper is to document the methods used to collect the samples, the collection locations, the analysis of soil type and potential to emit PM 10, and the sample variability, both within field and between fields of the same crop type.

  13. Center for Corporate Climate Leadership: Direct Fugitive Emissions from Refrigeration, Air Conditioning, Fire Suppression, and Industrial Gases

    Science.gov (United States)

    This guidance document focuses on several fugitive emissions sources that are common for organizations in many sectors: refrigeration and air conditioningsystems, fire suppression systems, and the purchase and release of industrial gases.

  14. Isotopically constrained lead sources in fugitive dust from unsurfaced roads in the southeast Missouri mining district

    Science.gov (United States)

    Witt, Emitt C.; Pribil, Michael; Hogan, John P; Wronkiewicz, David

    2016-01-01

    The isotopic composition of lead (Pb) in fugitive dust suspended by a vehicle from 13 unsurfaced roads in Missouri was measured to identify the source of Pb within an established long-term mining area. A three end-member model using 207Pb/206Pb and concentration as tracers resulted in fugitive dust samples plotting in the mixing field of well characterized heterogeneous end members. End members selected for this investigation include the 207Pb/206Pb for 1) a Pb-mixture representing mine tailings, 2) aerosol Pb-impacted soils within close proximity to the Buick secondary recycling smelter, and 3) an average of soils, rock cores and drill cuttings representing the background conditions. Aqua regia total concentrations and 207Pb/206Pb of mining area dust suggest that 35.4–84.3% of the source Pb in dust is associated with the mine tailings mixture, 9.1–52.7% is associated with the smelter mixture, and 0–21.6% is associated with background materials. Isotope ratios varied minimally within the operational phases of sequential extraction suggesting that mixing of all three Pb mixtures occurs throughout. Labile forms of Pb were attributed to all three end members. The extractable carbonate phase had as much as 96.6% of the total concentration associated with mine tailings, 51.8% associated with smelter deposition, and 34.2% with background. The next most labile geochemical phase (Fe + Mn Oxides) showed similar results with as much as 85.3% associated with mine tailings, 56.8% associated with smelter deposition, and 4.2% associated with the background soil.

  15. Anthropogenic fugitive, combustion and industrial dust is a significant, underrepresented fine particulate matter source in global atmospheric models

    Science.gov (United States)

    Philip, Sajeev; Martin, Randall V.; Snider, Graydon; Weagle, Crystal L.; van Donkelaar, Aaron; Brauer, Michael; Henze, Daven K.; Klimont, Zbigniew; Venkataraman, Chandra; Guttikunda, Sarath K.; Zhang, Qiang

    2017-04-01

    Global measurements of the elemental composition of fine particulate matter across several urban locations by the Surface Particulate Matter Network reveal an enhanced fraction of anthropogenic dust compared to natural dust sources, especially over Asia. We develop a global simulation of anthropogenic fugitive, combustion, and industrial dust which, to our knowledge, is partially missing or strongly underrepresented in global models. We estimate 2-16 μg m-3 increase in fine particulate mass concentration across East and South Asia by including anthropogenic fugitive, combustion, and industrial dust emissions. A simulation including anthropogenic fugitive, combustion, and industrial dust emissions increases the correlation from 0.06 to 0.66 of simulated fine dust in comparison with Surface Particulate Matter Network measurements at 13 globally dispersed locations, and reduces the low bias by 10% in total fine particulate mass in comparison with global in situ observations. Global population-weighted PM2.5 increases by 2.9 μg m-3 (10%). Our assessment ascertains the urgent need of including this underrepresented fine anthropogenic dust source into global bottom-up emission inventories and global models.

  16. 40 CFR 63.1445 - What work practice standards must I meet for my fugitive dust sources?

    Science.gov (United States)

    2010-07-01

    ...) Each transfer point in conveying systems used to transport fugitive dust materials. These points include, but are not limited to, transfer of material from one conveyor belt to another and transfer of... other enclosure, installing and operating a local hood capture system over the source and venting the...

  17. 40 CFR 63.9891 - What work practice standards must I meet for my fugitive dust sources?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 14 2010-07-01 2010-07-01 false What work practice standards must I meet for my fugitive dust sources? 63.9891 Section 63.9891 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES (CONTINUED)...

  18. Characterization of PM 10 source profiles for fugitive dust in Fushun-a city famous for coal

    Science.gov (United States)

    Kong, Shaofei; Ji, Yaqin; Lu, Bing; Chen, Li; Han, Bin; Li, Zhiyong; Bai, Zhipeng

    2011-09-01

    A total of 120 fugitive dust samples were collected to acquire chemical source profiles of PM 10 in Fushun including 27 soil dust samples, 32 road dust samples, 19 construction dust samples, 13 coal storage pile samples, 2 cement production samples, 13 coal-fired power plant fly ash samples, 5 fly ash samples from iron smelt plant and 9 samples from industrial raw material and production piles. The samples were classified as 20 subtypes. The dust samples were dried, sieved, resuspended and sampled through a PM 10 inlet onto filters, and then chemically analyzed. Inductively coupled plasma-atomic emission spectrometry, ion chromatograph and thermal/optical reflectance methods were adopted for analyzing twenty elements including Na, Mg, Al, Si, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Pb and Hg and nine ions including Na +, NH 4+, K +, Mg 2+, Ca 2+, F -, Cl -, NO 3- and SO 42- as well as OC and EC, respectively. The chemical compositions were compared for 20 subtypes. Si and Ca were the most abundant elements in all the fugitive dust profiles. Enrichment factors of elements in fly ashes compared to raw coal were calculated with Fe as reference element. The highest enriched elements were Ni, Cu, Zn and Pb. Significant difference existed among PM 10 profiles with the coefficient of divergence values ranging from 0.28 to 0.78. Profiles were compared with others. Si exhibited lower content in this study for soil and road dust while EC and Cr showed much higher content compared to others indicating the influence of coal mining and industries activities in Fushun. This was validated by source signatures analysis which indicated almost all the fugitive dust were relative to coal and may also be influenced by metallurgy. The ratios of Mn/V, V/Ni, Zn/Pb and Zn/Cd were calculated for source identification. Elemental ratios may vary widely even for the same source types with different processing courses. Chemical profiles of fugitive dust should be established based

  19. Deposition and removal of fugitive dust in the arid southwestern United States: measurements and model results.

    Science.gov (United States)

    Etyemezian, Vic; Ahonen, Sean; Nikolic, Djordje; Gillies, John; Kuhns, Hampden; Gillette, Dale; Veranth, John

    2004-09-01

    This work was motivated by the need to better reconcile emission factors for fugitive dust with the amount of geologic material found on ambient filter samples. The deposition of particulate matter with aerodynamic diameter less than or equal to 10 microm (PM10), generated by travel over an unpaved road, over the first 100 m of transport downwind of the road was examined at Ft. Bliss, near El Paso, TX. The field conditions, typical for warm days in the arid southwestern United States, represented sparsely vegetated terrain under neutral to unstable atmospheric conditions. Emission fluxes of PM10 dust were obtained from towers downwind of the unpaved road at 7, 50, and 100 m. The horizontal flux measurements at the 7 m and 100 m towers indicated that PM10 deposition to the vegetation and ground was too small to measure. The data indicated, with 95% confidence, that the loss of PM10 between the source of emission at the unpaved road, represented by the 7 m tower, and a point 100 m downwind was less than 9.5%. A Gaussian model was used to simulate the plume. Values of the vertical standard deviation sigma(z) and the deposition velocity Vd were similar to the U.S. Environmental Protection Agency (EPA) ISC3 model. For the field conditions, the model predicted that removal of PM10 unpaved road dust by deposition over the distance between the point of emission and 100 m downwind would be less than 5%. However, the model results also indicated that particles larger than 10 microm (aerodynamic diameter) would deposit more appreciably. The model was consistent with changes observed in size distributions between 7 m and 100 m downwind, which were measured with optical particle counters. The Gaussian model predictions were also compared with another study conducted over rough terrain and stable atmospheric conditions. Under such conditions, measured PM10 removal rates over 95 m of downwind transport were reported to be between 86% and 89%, whereas the Gaussian model predicted

  20. Fugitive Felons

    Data.gov (United States)

    Social Security Administration — The Fugitive Felon Reporting and Tracking System (FRATS) houses fugitive data submitted by reporters (RIDs) and warrant agencies (WAIDs). It also controls and tracks...

  1. Road fugitive dust emission characteristics in Beijing during Olympics Game 2008 in Beijing, China

    Science.gov (United States)

    Shou-bin, Fan; Gang, Tian; Gang, Li; Yu-hu, Huang; Jian-ping, Qin; Shui-yuan, Cheng

    2009-12-01

    Eighty road dust-fall (DF) monitoring sites and 14 background monitoring sites were established in the Beijing metropolitan area, and monitoring was conducted from January 2006 to December 2008. The dust-fall attributable to roads (ΔDF) showed a clear decline from 2006 to 2008. Dust-fall levels decreased across different road types from freeway > major arterial roads > minor arterial roads > collector roads > background sites. The ΔDF showed declines of 65%, 55%, 65% and 84% respectively for freeways, major arterial, minor arterial and collector roads from August 2007 to August 2008, and declines of 77%, 76%, 82% and 82% between August 2006 and August 2008. The ΔDF declined by 80%, 79%, 82% and 69% for freeways, major arterial, minor arterial and collector roads respectively between September 2007 and September 2008, and declined by 84%, 88%, 80% and 81% between September 2006 and September 2008. Eighty samples were collected in August 2007 and August 2008 and analyzed for silt loading. PM 10 emission factors and emission strengths were calculated using the AP-42 model. The silt loading reduced by 77%, 35%, 61%, 59% and 75% for freeways, major arterial, minor arterial, collector and local roads respectively. The PM 10 emission factors were reduced by 57%, 15%, 36%, 51% and 61% and the PM 10 emission strength declined by 70%, 40%, 55%, 65% and 72% for freeways, major arterial, minor arterial, collector and local roads respectively between August 2007 and August 2008. The decline is consistent with the reduction in road dust-fall.

  2. Impairment of soil health due to fly ash-fugitive dust deposition from coal-fired thermal power plants.

    Science.gov (United States)

    Raja, R; Nayak, A K; Shukla, A K; Rao, K S; Gautam, Priyanka; Lal, B; Tripathi, R; Shahid, M; Panda, B B; Kumar, A; Bhattacharyya, P; Bardhan, G; Gupta, S; Patra, D K

    2015-11-01

    Thermal power stations apart from being source of energy supply are causing soil pollution leading to its degradation in fertility and contamination. Fine particle and trace element emissions from energy production in coal-fired thermal power plants are associated with significant adverse effects on human, animal, and soil health. Contamination of soil with cadmium, nickel, copper, lead, arsenic, chromium, and zinc can be a primary route of human exposure to these potentially toxic elements. The environmental evaluation of surrounding soil of thermal power plants in Odisha may serve a model study to get the insight into hazards they are causing. The study investigates the impact of fly ash-fugitive dust (FAFD) deposition from coal-fired thermal power plant emissions on soil properties including trace element concentration, pH, and soil enzymatic activities. Higher FAFD deposition was found in the close proximity of power plants, which led to high pH and greater accumulation of heavy metals. Among the three power plants, in the vicinity of NALCO, higher concentrations of soil organic carbon and nitrogen was observed whereas, higher phosphorus content was recorded in the proximity of NTPC. Multivariate statistical analysis of different variables and their association indicated that FAFD deposition and soil properties were influenced by the source of emissions and distance from source of emission. Pollution in soil profiles and high risk areas were detected and visualized using surface maps based on Kriging interpolation. The concentrations of chromium and arsenic were higher in the soil where FAFD deposition was more. Observance of relatively high concentration of heavy metals like cadmium, lead, nickel, and arsenic and a low concentration of enzymatic activity in proximity to the emission source indicated a possible link with anthropogenic emissions.

  3. Environmentally Friendly Binders from Wood for Dust Suppression

    OpenAIRE

    Brovkina, J; Šuļga, G; Ozoliņš, J

    2008-01-01

    Dust suppression is an important widespread problem for people and animals, who live close to unsealed roads, mining, thermal power plants, eroded soil areas, etc. The dust produced by these objects has a lot of the negative effects on environment, including contamination of air and water, which causing health problems for earth inhabitants. When a surface of a dust-laden object dries out, the adhesiveness between its particles is reduced. The fine particles blows away and give rise to dust. ...

  4. Organization and effectivity of works on dust suppressing in the special zone of the Chernobyl' NPP

    International Nuclear Information System (INIS)

    Shimin, S.A.; Krapchatov, V.P.; Nad''yarnykh, G.V.; Komarov, V.I.; Andreev, Yu.B.; Samojlenko, Yu.N.

    1989-01-01

    In 1988 three methods of dust suppressing were used: regular watering of roads, chemical treatment of roadsides and dusting sections of area, long-time biologochemical fixation of open sections of area, including sowing with grass and simultaneous treatment by dust-suppressing compositions. Preliminary treatment of objects by polymeric compositions was an effective action to reduce dust-raising. 3 refs.; 3 figs

  5. A new approach to developing a fugitive road dust emission inventory and emission trend from 2006 to 2010 in the beijing metropolitan area, china.

    Science.gov (United States)

    Fan, Shoubin; Tian, Gang; Cheng, Shuiyuan; Qin, Jianping

    2013-07-01

    The USEPA emission factor (AP-42) of fugitive road dust (FRD) is widely used in establishing emission inventories. However, road silt loading sampling for AP-42 is expensive, time consuming, and dangerous. Therefore, a new method for establishing emission inventories based on road dust-fall (DF) monitors is described. Between January 2006 and December 2010, DF was monitored at 40 sites (80 samples), and background dust fall (DF) was monitored at 14 sites in the Beijing metropolitan area. Also during this period, 58 samples of road silt loadings were taken and used in the AP-42 emission factor equation to calculate FRD with particulate matter ≤10 μm in diameter [FRD(PM)] emission from the roads. Simultaneous measurement of FRD(PM) emissions calculated by AP-42 and ΔDF (i.e., the difference between the DF and DF) measured using gauges showed that the FRD(PM) emission for road dust was proportional to the ΔDF ( = 0.92). The FRD(PM) emission (kg km × 30 d) was calculated using the monitored ΔDF (t km × 30 d) by the formulation FRD(PM) = 278.3 × ΔDF - 1151.2. The ΔDF showed a general decline from 2006 to 2010. In particular, there was a sharp decline in August, September, and October 2008 due to strict dust controls enforced during the 2008 Olympic Games. Although there was a small increase in ΔDF after the Games, by the end of 2010 values were still lower than those before the Games. Using the 2006 ΔDF value as a benchmark, ΔDF values declined by 24.7, 33.0, 38.3, and 31.4% in 2007, 2008, 2009, and 2010, respectively. Based on using AP-42 calculations from silt loading and traffic information in 2007, the FRD(PM) emission distribution in the Beijing metropolitan area was mapped, and there were 2.05 × 10 tons of FRD(PM) emitted in 2007. The FRD(PM) from 2006 to 2010 was calculated by the ΔDF values. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  6. Suppression of dust explosions and ignition spots in biomass- fired power plants

    Energy Technology Data Exchange (ETDEWEB)

    Wilen, C.; Rautalin, A. [VTT Energy, Espoo (Finland)

    1997-12-01

    Dust explosion characteristics of forest residue dust both at normal pressure and at elevated initial pressure have been determined in previous studies. These indices give a good base for evaluating the usability of suppression systems to obtain a sufficient level of operational safety in biomass fuel handling equipment. The objectives of this project were to evaluate the usability of suppression systems and to demonstrate dust explosion suppression at elevated initial pressure. Suppression tests at 1 - 20 bar pressure will be carried out in co-operation with CTDD of British Coal, Kiddy Fire Protection and Health and Safety Executive. The tests with coal and biomass dust are scheduled to be started in March 1996 in Great Britain. In the second task of the project, self-ignition properties of forest residue dust and straw dust have been measured in a flow-through system simulating slow drying of the fuel

  7. Suppression of dust explosions and ignition spots in biomass-fired power plants

    Energy Technology Data Exchange (ETDEWEB)

    Wilen, C.; Rautalin, A.

    1995-12-31

    Dust explosion characteristics of forest residue dust both at normal pressure and at elevated initial pressure have been determined in previous studies. These indices give a good base for evaluating the usability of suppression systems to obtain a sufficient level of peritoneal safety in biomass fuel handling equipment. The objectives of this project were to evaluate the usability of suppression systems and to demonstrate dust explosion suppression at elevated initial pressure. Suppression tests at 1 - 20 bar pressure will be carried out in co-operation with CTDD of British Coal, Kiddy Fire Protection and Health and Safety Executive. The tests with coal and biomass dust are scheduled to be started in March 1996 in Great Britain. In the second task of the project, self-ignition properties of forest residue dust and straw dust have been measured in a flow-through system simulating slow drying of the fuel

  8. Comparison of conventional and bio-treated methods as dust suppressants.

    Science.gov (United States)

    Naeimi, Maryam; Chu, Jian

    2017-10-01

    Dust is an environmental, geotechnical, health, and economical hazard. Fugitive dust emanating along transportation systems such as roads, railways, and airports especially can have significant impacts on health, safety, material loss, cost of maintenance, and interfere with the facilities. Quantitative studies on the effectiveness of the proper dust palliatives and their environmental impact have been studied with a number of biological and chemical methods. The objective of this study was to establish a method for using the microbial Induced calcium carbonate precipitation (MICP) approach to reduce the percent of mass loss against erosive force of wind regarding to the concentration and characteristics of aggregate used, climate, and traffic amounts. The results of this study showed that the required precipitation for dust control of sand by 70% is less than 15 g CaCO 3 /m 2 between sand grains in bio-treated sand. The wind tunnel test results of this study also indicate that the effectiveness of the bio-treatment method for dust control depends on many variables, such as the percent of precipitated calcium carbonate and tensile strength.

  9. Activated Charcoal Suppresses Breeding of the House Dust Mite, Dermatophagoides Pteronyssinus, in Culture

    Science.gov (United States)

    Nam, Hae-Seon; Lee, Sun-Hwa; Kim, Sung-Ho; Lee, Sang-Han; Crane, Julian

    2007-01-01

    House dust mite sensitized asthmatics are advised to practice allergen avoidance. Charcoal pillows are used in Korea with unsubstantiated claims regarding their efficacy in alleviating asthma symptoms. We tested the effects of activated charcoal on breeding of house dust mites in culture. Twenty live adult house dust mites (Dermatophagoides pteronyssinus) were inoculated, 10 replicates, on culture media containing 0%, 1%, 3%, 5%, 10%, and 20% activated charcoal and incubated at 25℃ and a relative humidity of 75%. After four weeks, the mean numbers of live house dust mites were 286, 176, 46, 16, 7, and 0 for the 0%, 1%, 3%, 5%, 10%, and 20% charcoal-containing culture media, respectively. Thus, activated charcoal suppresses breeding of house dust mites and offers a new promising method for house dust mite control. PMID:17449957

  10. Suppression of polymethyl methacrylate dust explosion by ultrafine water mist/additives.

    Science.gov (United States)

    Gan, Bo; Li, Bei; Jiang, Haipeng; Bi, Mingshu; Gao, Wei

    2018-06-05

    The suppressions of ultrafine water mists containing additives (NaCl and NaHCO 3 ) on 100 nm, 5 μm, and 30 μm polymethyl methacrylate (PMMA) dust explosions were experimentally studied in a dust-explosion apparatus. High-speed photography showed that maximum vertical positions and flame propagation velocities were significantly decreased by suppression with ultrafine water mist/additives. Flame propagation velocities in 100 nm, 5 μm, and 30 μm dust explosions suppressed by the ultrafine pure water mist were reduced by 48.2%, 27.7%, and 15.3%, respectively. Maximum temperatures and temperature rising rates measured by a fine thermocouple in nano- and micro-PMMA dust explosions were also significantly decreased. It was proved that the addition of NaCl and NaHCO 3 improved the suppression effects of the ultrafine pure water mist. The improvement of explosion suppression by an 8% NaHCO 3 mist was superior to that of a 16% NaCl mist. The suppression mechanisms of ultrafine water mist/additives are further discussed by analyzing the physical and chemical effects. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Assessment of efficiency of windbreak and dust suppression walls for coal terminals

    Science.gov (United States)

    Moskovaya, I. V.; Olishevskiy, A. T.; Lazareva, L. P.

    2017-10-01

    This paper analyzes the methods for measuring atmospheric concentrations of coal dust and assesses the impact of operating activities of the coal terminal at the port of Vanino on the atmospheric air. The authors suggest an installation diagram of windbreak and dust suppression walls for the coal terminal at the port of Vanino; analyze the efficiency of such walls with regard to coal storage conditions, coal characteristics, and storage area; and put forward measures to further reduce the environmental impact of the terminal.

  12. Technology Assessment of Dust Suppression Techniques Applied During Structural Demolition. Topical Report August1, 1995 - October 30, 1996

    International Nuclear Information System (INIS)

    Boudreaux, J.F.; Ebadian, M.A.; Williams, P.T.; Dua, S.K.

    1998-01-01

    Hanford, Fernald, Savannah River, and other sites are currently reviewing technologies that can be implemented to demolish buildings in a cost-effective manner. In order to demolish a structure properly and, at the same time, minimize the amount of dust generated from a given technology, an evaluation must be conducted to choose the most appropriate dust suppression technology given site-specific conditions. Thus, the purpose of this research, which was carried out at the Hemispheric Center for Environmental Technology (HCET) at Florida International University, was to conduct an experimental study of dust aerosol abatement (dust suppression) methods as applied to nuclear D and D. This experimental study targeted the problem of dust suppression during the demolition of nuclear facilities. The resulting data were employed to assist in the development of mathematical correlations that can be applied to predict dust generation during structural demolition

  13. Dustiness of chopped straw as affected by lignosulfonate as a dust suppressant.

    Science.gov (United States)

    Breum, N O; Nielsen, B H; Lyngbye, M; Midtgård, U

    1999-01-01

    Many sources add to the concentration of bioaerosols in livestock buildings, and source control is the number one priority for keeping a low concentration. Straw is a common but dusty bedding material in livestock buildings and the present study is focused on the dustiness of chopped straw (barley) as affected by lignosulfonate (LS) as a dust suppressant. A LS-solution was aerosolized in a spray chamber fitted to an existing bedding chopper to allow the chopped straw to adsorb the LS-solution. The dustiness of straw treated with LS was compared to non-treated straw. As storage conditions may affect dustiness, the study included treated straw kept for 4 weeks in sealed plastic bags. Dustiness of the chopped straw was measured in terms of the potential of the straw to emit bioaerosols in a rotating drum. The LS-treated straw proved low in dustiness compared to the non-treated straw. The dustiness with respect to the mass of dust was reduced by at least a factor of 6, and for fungi and endotoxin the factors of reduction were 4 and 3, respectively. Dustiness of LS-treated straw kept in plastic bags was reduced by a factor of 2 for mass of dust and by a factor of 4 for endotoxin, but dustiness for fungi was increased by a factor of 3. It is concluded that lignosulfonate has potential as a dust suppressant for chopped straw.

  14. A water soluble additive to suppress respirable dust from concrete-cutting chainsaws: a case study.

    Science.gov (United States)

    Summers, Michael P; Parmigiani, John P

    2015-01-01

    Respirable dust is of particular concern in the construction industry because it contains crystalline silica. Respirable forms of silica are a severe health threat because they heighten the risk of numerous respirable diseases. Concrete cutting, a common work practice in the construction industry, is a major contributor to dust generation. No studies have been found that focus on the dust suppression of concrete-cutting chainsaws, presumably because, during normal operation water is supplied continuously and copiously to the dust generation points. However, there is a desire to better understand dust creation at low water flow rates. In this case study, a water-soluble surfactant additive was used in the chainsaw's water supply. Cutting was performed on a free-standing concrete wall in a covered outdoor lab with a hand-held, gas-powered, concrete-cutting chainsaw. Air was sampled at the operator's lapel, and around the concrete wall to simulate nearby personnel. Two additive concentrations were tested (2.0% and 0.2%), across a range of fluid flow rates (0.38-3.8 Lpm [0.1-1.0 gpm] at 0.38 Lpm [0.1 gpm] increments). Results indicate that when a lower concentration of additive is used exposure levels increase. However, all exposure levels, once adjusted for 3 hours of continuous cutting in an 8-hour work shift, are below the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) of 5 mg/m(3). Estimates were made using trend lines to predict the fluid flow rates that would cause respirable dust exposure to exceed both the OSHA PEL and the American Conference of Governmental Industrial Hygienists (ACGIH®) threshold limit value (TLV).

  15. Emission Inventory for Fugitive Emissions in Denmark

    DEFF Research Database (Denmark)

    Plejdrup, Marlene Schmidt; Nielsen, Ole-Kenneth; Nielsen, Malene

    This report presents the methodology and data used in the Danish inventory of fugitive emissions from fuels for the years until 2007. The inventory of fugitive emissions includes CO2, CH4, N2O, NOx, CO, NMVOC, SO2, dioxin, PAH and particulate matter. In 2007 the total Danish emission of greenhouse...... gasses was 66 641 Gg CO2-eqvivalents. Fugitive emissions from fuels account for 496 Gg CO2-eqvivalents or approximately 1 %. The major part of the fugitive emissions are emitted as CO2 (74 %) due to flaring of oil and gas. The major source of fugitive CH4 emission is extraction of oil and gas...... in the North Sea, refining of oil and loading of oil onto ships both offshore and onshore. The fugitive emissions of NMVOC originate for the major part from extraction, loading of ships, transmission and distribution of oil and to a much lesser degree from natural gas and fugitive emissions from gas stations...

  16. Controlling fugitive emissions from mechanical seals

    International Nuclear Information System (INIS)

    Adams, W.V.

    1992-01-01

    This paper reports that enactment of the 1990 Federal Clean Air Amendments will sharply focus efforts in the process industries to reduce fugitive emissions. Moreover, state and local governments may be imposing stricter laws and regulations which will affect allowable fugitive emissions from U.S. refineries and process plants. Plants outside the U.S. have similar concerns. Clearly, mechanical seals for process pumps represent an enormous population and is one category of equipment destined for careful evaluation as a means to control fugitive emissions. Fugitive are unintentional emissions from valves, pumps, flanges, compressors, etc., as opposed to point-source emissions from stacks, vents and flares. Fugitive emissions do not occur as a part of normal plant operations, but result from the effects of: Malfunctions, Age, Lack of proper maintenance, Operator error, Improper equipment specification, Use of inferior technology, and externally caused damage

  17. Fugitive emissions from nanopowder manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Trompetter, W. J., E-mail: b.trompetter@gns.cri.nz; Ancelet, T.; Davy, P. K.; Kennedy, J. [GNS Science (New Zealand)

    2016-07-15

    In response to health and safety questions and concerns regarding particulate matter emissions from equipment used for synthesizing NiFe and TiO{sub 2} nanopowders, a study was undertaken to assess their impact on the air quality inside and outside a laboratory where the manufacturing equipment is operated. Elemental concentrations determined by ion beam analysis (IBA) of air particulate matter (PM) samples collected hourly with a Streaker{sup TM} sampler were used to identify possible sources and estimate contributions from nanopowder production and other sources. The fugitive nanopowder emissions were the highest at the indoor sampling location when powders were being manufactured. Average fugitive emissions of 210 ng m{sup −3} (1-h average) (maximum 2163 ng m{sup −3} 1-h average) represented 2 % (maximum 20 %) of the average PM collected (9359 ng m{sup −3} 1-h average). The measured NiFe alloy or TiO{sub 2} PM concentrations were much smaller than the 8-h time-weighted average (TWA) workplace exposure standards (WES) for these materials (≥1,000,000 ng m{sup −3}). Most PM was found to be from infiltrated outdoor ambient sources. This suggests that nanopowder production in the laboratory is not likely to have adverse health effects on individuals using the equipment, although further improvements can be made to further limit exposure.Graphical abstract.

  18. Technology and Policy for Suppressing Grain Dust Explosions in Storage Facilities

    National Research Council Canada - National Science Library

    1995-01-01

    To ensure workplace safety, grain handling facilities engage in a variety of activities to control the accumulation of grain dust, such as good housekeeping practices, pneumatic systems, and liquid additives...

  19. Fugitive methane emissions from an agricultural biodigester

    International Nuclear Information System (INIS)

    Flesch, Thomas K.; Desjardins, Raymond L.; Worth, Devon

    2011-01-01

    The use of agricultural biodigesters provides a strategy for reducing greenhouse gas (GHG) emissions while generating energy. The GHG reduction associated with a biodigester will be affected by fugitive emissions from the facility. The objective of this study was to measure fugitive methane (CH 4 ) emissions from a Canadian biodigester. The facility uses anaerobic digestion to produce biogas from cattle manure and other organic feedstock, which is burnt to generate electricity (1 MW capacity) and heat. An inverse dispersion technique was used to calculate emissions. Fugitive emissions were related to the operating state of the biodigester, and over four seasonal campaigns the emission rate averaged 3.2, 0.8, and 26.6 kg CH 4 hr -1 for normal operations, maintenance, and flaring periods, respectively. During normal operations the average fugitive emission rate corresponded to 3.1% of the CH 4 gas production rate. -- Highlights: → Biodigesters reduce greenhouse gas emissions. → Net emission reduction affected by fugitive emissions. → Fugitive CH 4 measured at agricultural biodigester (1 MW generating capacity). → Emissions were 3.1% of gas production. → Emissions lower than assumed in carbon credit protocols.

  20. USE OF BIOLOGICAL ADHESIVE FOR EFFECTIVE DUST SUPPRESSION IN MINING OPERATIONS

    Directory of Open Access Journals (Sweden)

    Aleksandr Sergeevich Danilov

    2015-11-01

    Full Text Available This article explores modern methods of reclamation of lands disturbed processes of mining, based on monitoring disturbed lands using unmanned aircraft and dusty surfaces coated biologically active adhesive, biological foam. In the article new highly efficint methods of remote monitoring of environment components are considered on based of unmanned aircrafts. For monitoring, it is suggested to draw complexes based of small unmanned aircraft vehicle, equipped with special equipment (a digital camera, a thermal imaging camera, dust meter. Land reclamation on the biological stage is encouraged by using new bio-adhesives, developed on the basis of polysaccharides and various microorganisms. This composition helps reduce the consumption of fertilizers, pesticides and other components, pioneer in growing crops on dusty surfaces in the disturbed lands. As a result of such an event, dust discharge from the surface technogenic structures is reduced up to 10 times.

  1. DA-9601 suppresses 2, 4-dinitrochlorobenzene and dust mite extract-induced atopic dermatitis-like skin lesions.

    Science.gov (United States)

    Choi, Eun-Ju; Lee, Soyoung; Hwang, Ji-Sun; Im, Sin-Hyeog; Jun, Chang-Duk; Lee, Hyun-Shik; Kim, Sang-Hyun

    2011-09-01

    DA-9601 (Stillen™) is a novel anti-peptic formulation prepared from the ethanol extracts of Artemisia asiatica possessing anti-oxidative, anti-allergic and anti-inflammatory activities. However, their effect on atopic dermatitis (AD) has not been studied yet. In this study, we report that topical application of DA-9601 suppressed house dust mite extract (Dermatophagoides farinae extract, DFE) and 2, 4-dinitrochlorobenzene (DNCB)-induced AD-like skin lesions in BALB/c mice model. We established atopic dermatitis model in BALB/c mice by repeated local exposure of DFE/DNCB to the ears. Repeated alternative treatment of DFE/DNCB caused AD-like lesions. DA-9601 reduced AD-like skin lesions based on ear thickness and histopathological analysis, and serum IgE levels. DA-9601 inhibited mast cell infiltration into the ear and elevation of serum histamine in AD model. In addition, DA-9601 suppressed DFE/DNCB-induced expression of IL-4, IL-13, IL-31, and TNF-α in the ears. Taken together, our results showed that topical application of DA-9601 exerts beneficial effects in animal model of AD, suggesting that DA-9601 might be a candidate for the treatment of AD. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Monitoring of fugitive emissions in petrochemical plant

    Energy Technology Data Exchange (ETDEWEB)

    Brandao, Rozilda F. [Companhia Petroquimica do Nordeste (COPENE), Camacari, BA (Brazil). Div. de Engenharia Ambiental

    1993-12-31

    COPENE (Petroquimica do Nordeste S/A) has been implanting a program of fugitive emissions adapted to its reality, trying to promote a continuous improvement in its employees` working conditions and in environmental protection. This paper presents the methodology for the elaboration of this program and the conclusions of some surveys which were already completed (author). 4 refs., 7 figs., 3 tabs.

  3. Fate of Magnesium Chloride Brine Applied to Suppress Dust from Unpaved Roads at the INEEL Subsurface Disposal Area

    Energy Technology Data Exchange (ETDEWEB)

    Larry Hull; Carolyn Bishop

    2004-02-01

    Between 1984 and 1993, MgCl2 brine was used to suppress dust on unpaved roads at a radioactive waste subsurface disposal area. Because Cl– might enhance corrosion of buried metals in the waste, we investigated the distribution and fate of Cl– in the vadose zone using pore water samples collected from suction lysimeters and soluble salt concentrations extracted from sediment samples. The Cl/Br mass ratio and the total dissolved Cl– concentration of pore water show that brine contamination occurs primarily within 13 m of treated roads, but can extend as much as 30 m laterally in near-surface sedimentary deposits. Within the deep vadose zone, which consists of interlayered basalt lava flows and sedimentary interbeds, brine has moved up to 110 m laterally. This lateral migration suggests formation of perched water and horizontal transport during periods of high recharge. In a few locations, brine migrated to depths of 67 m within 3 to 5 yr. Elevated Cl– concentrations were found to depths of 2 m in roadbed material. In drainage ditches along roads, where runoff accumulates and recharge of surface water is high, Cl– was flushed from the sediments in 3 to 4 yr. In areas of lower recharge, Cl– remained in the sediments after 5 yr. Vertical brine movement is directly related to surface recharge through sediments. The distribution of Cl– in pore water and sediments is consistent with estimates of vadose zone residence times and spatial distribution of surface water recharge from other investigations at the subsurface

  4. Emission inventory for fugitive emissions from fuel in Denmark

    DEFF Research Database (Denmark)

    Plejdrup, Marlene Schmidt; Nielsen, Ole-Kenneth; Nielsen, Malene

    This report presents the methodology and data used in the Danish inventory of fugitive emissions from fuels for the years until 2013. The inventory of fugitive emissions includes CO2, CH4, N2O, SO2, NOx, NMVOC, CO, particulate matter, Black carbon, heavy metals, dioxin and PAHs. In 2013 the total...... Danish emission of greenhouse gasses was 54 584 Gg CO2 equivalents. Fugitive emissions from fuels account for 387 Gg CO2 equivalents or approximately 1 %. The major part of the fugitive emissions are emitted as CO2 (61 %) mainly from flaring in upstream oil and gas production. The major source...... of fugitive CH4 emission is production of oil and gas in the North Sea, refining of oil and loading of oil onto ships both offshore and onshore. The fugitive emissions of NMVOC originate for the major part from oil and gas production, loading of ships, transmission and distribution of oil, and to a less...

  5. Fort Carson Fugitive Dust Generation and Transport Study: Lessons Learned.

    Science.gov (United States)

    1981-11-01

    collection, and the data 7 *11 analysis routines. A discussion of how the research results could be applied and a detailed breakdown of labor and equipment...stations at the Community Services Building No. 1526 and on Tank Table VII employed the Electronic Weather Station built by Clima - tronics Corporation of

  6. A review on the effectiveness of street sweeping, washing and dust suppressants as urban PM control methods.

    Science.gov (United States)

    Amato, F; Querol, X; Johansson, C; Nagl, C; Alastuey, A

    2010-07-15

    Given the absence of a definitive threshold for atmospheric particulate matter (PM)-induced adverse health effects and the evidence of road traffic as a main contributor to PM-urban levels, there is a general agreement in reducing PM-associated health risks by firstly focusing on vehicle traffic sector. Beside the reduction of primary exhaust emissions, recent potential measures are challenging to reduce emissions of particulate matter from abrasion and resuspension processes given the high potential health burden of heavy metals and metalloids sourced by vehicle-wear particles (brakes, tires, rotor, discs and catalysts) and of coarse particles (PM(2.5-10)). Some mitigating measures can be adopted in order to reduce road dust emissions from paved roads by removing or binding those particles already deposited and easy to be resuspended by traffic-generated turbulence. Sweeping, water flushing and use of chemical suppressants are usually more commonly employed to try to diminish emissions, but evaluating the effectiveness of preventive measures on improving air quality is a difficult task, consequently there is a general dearth of information about their effectiveness in reducing ambient PM concentrations. In particular, the scientific bibliography seems to be particularly scarce, whilst most of the information comes from local authorities committees. Consequently the existing reports are often aimed only to the municipalities and in the native language, with an objective difficulty for the international scientific community to access to them. For this review we have gathered contributions from some of major experts in this field, with the purpose of taking advantage of their background and personal awareness about any kind of related reports even not in English. Furthermore, the results we have gathered are often dissimilar, probably due to the different local conditions (weather, road pavement conditions etc.), therefore another objective of the review is to make a

  7. Morus alba L. suppresses the development of atopic dermatitis induced by the house dust mite in NC/Nga mice.

    Science.gov (United States)

    Lim, Hye-Sun; Ha, Hyekyung; Lee, Hoyoung; Lee, Jun Kyung; Lee, Mee-Young; Shin, Hyeun-Kyoo

    2014-04-23

    Morus alba, a medicinal plant in Asia, has been used traditionally to treat diabetes mellitus and hypoglycemia. However, the effects of M. alba extract (MAE) on atopic dermatitis have not been verified scientifically. We investigated the effects of MAE on atopic dermatitis through in vitro and in vivo experiments. We evaluated the effects of MAE on the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in RAW 264.7, as well as thymus and activation-regulated chemokine (TARC/CCL17) in HaCaT cells. In an in vivo experiment, atopic dermatitis was induced by topical application of house dust mites for four weeks, and the protective effects of MAE were investigated by measuring the severity of the skin reaction on the back and ears, the plasma levels of immunoglobulin E (IgE) and histamine, and histopathological changes in the skin on the back and ears. MAE suppressed the production of NO and PGE2 in RAW 264.7 cells, as well as TARC in HaCaT cells, in a dose-dependent manner. MAE treatment of NC/Nga mice reduced the severity of dermatitis and the plasma levels of IgE and histamine. MAE also reduced the histological manifestations of atopic dermatitis-like skin lesions such as erosion, hyperplasia of the epidermis and dermis, and inflammatory cell infiltration in the skin on the back and ears. Our results suggest that MAE has potent inhibitory effects on atopic dermatitis-like lesion and may be a beneficial natural resource for the treatment of atopic dermatitis.

  8. Fugitive Emission Control for the APE 1236 Deactivation Furnace

    Science.gov (United States)

    2007-03-01

    at Tooele Army Depot ( TEAD ) to contain fugitive emissions. A monitoring system was designed and installed to measure and record the effects of...door brought the average pressure to negative and the TEAD furnace into compliance with fugitive emissions requirements. DISCLAIMER: The contents...Pollutants NI National Instruments Corporation RCRA Resource Conservation and Recovery Act TEAD Tooele Army Depot UPS uninterrupted power supply

  9. Evaluation of Uncertainties in Measuring Particulate Matter Emission Factors from Atmospheric Fugitive Sources Using Optical Remote Sensing

    Science.gov (United States)

    Yuen, W.; Ma, Q.; Du, K.; Koloutsou-Vakakis, S.; Rood, M. J.

    2015-12-01

    Measurements of particulate matter (PM) emissions generated from fugitive sources are of interest in air pollution studies, since such emissions vary widely both spatially and temporally. This research focuses on determining the uncertainties in quantifying fugitive PM emission factors (EFs) generated from mobile vehicles using a vertical scanning micro-pulse lidar (MPL). The goal of this research is to identify the greatest sources of uncertainty of the applied lidar technique in determining fugitive PM EFs, and to recommend methods to reduce the uncertainties in this measurement. The MPL detects the PM plume generated by mobile fugitive sources that are carried downwind to the MPL's vertical scanning plane. Range-resolved MPL signals are measured, corrected, and converted to light extinction coefficients, through inversion of the lidar equation and calculation of the lidar ratio. In this research, both the near-end and far-end lidar equation inversion methods are considered. Range-resolved PM mass concentrations are then determined from the extinction coefficient measurements using the measured mass extinction efficiency (MEE) value, which is an intensive PM property. MEE is determined by collocated PM mass concentration and light extinction measurements, provided respectively by a DustTrak and an open-path laser transmissometer. These PM mass concentrations are then integrated with wind information, duration of plume event, and vehicle distance travelled to obtain fugitive PM EFs. To obtain the uncertainty of PM EFs, uncertainties in MPL signals, lidar ratio, MEE, and wind variation are considered. Error propagation method is applied to each of the above intermediate steps to aggregate uncertainty sources. Results include determination of uncertainties in each intermediate step, and comparison of uncertainties between the use of near-end and far-end lidar equation inversion methods.

  10. Toxoplasma gondii Infection Suppresses House Dust Mite Extract-Induced Atopic Dermatitis in NC/Nga Mice.

    Science.gov (United States)

    Jeong, Young Il; Hong, Sung Hee; Cho, Shin Hyeong; Lee, Won Ja; Lee, Sang Eun

    2015-11-01

    Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan parasite that infects humans and animals via congenital or postnatal routes, and it is found worldwide. Modulation of the immune system by parasite infection is proposed to suppress allergic inflammation. Growing evidences have shown that interleukin (IL)-10-producing regulatory B cells (B(regs)) and CD4+CD25+FoxP3+ regulatory T cells (T(regs)) induced by parasite infection play a critical role in allergic or autoimmune diseases because these cells regulate negatively cellular immune responses and inflammation. Currently, the role of IL-10-producing regulatory B cells in host immune response during T. gondii infection is unknown. In this study, we investigate whether T. gondii infection can suppress the development of unrelated atopic dermatitis (AD)-like lesions. AD is a chronically relapsing inflammatory skin disease accompanied by severe itching; for this, we used NC/Nga mice, a well-known experimental model of systemic AD. Repeated exposure to Dermatophagoides farinae crude extract (DfE), known as a major environmental allergen, evokes AD-like skin lesions in NC/Nga mice under specific pathogen-free conditions. NC/Nga mice were intraperitoneally infected with 10 cysts of T. gondii. T. gondii infection significantly ameliorated AD-like skin lesions in NC/Nga mice. The subpopulation of B(regs) and T(regs) in the AD mice was expanded in the course of T. gondii infection. In addition, T. gondii infection inhibited Th2 and enhanced Th1 immune response in the DfE-treated AD mice. We have experimentally demonstrated for the first time that T. gondii infection ameliorated AD-like skin lesions in a mouse model of AD. Our study could in part explain the mechanisms of how parasite infection prevents the development of allergic disorder. Therefore, these immunemechanisms induced by T. gondii infection may be beneficial for the host in terms of reduced risk of allergic immune reactions.

  11. Suppression of dust mite extract and 2,4-dinitrochlorobenzene-induced atopic dermatitis by the water extract of Lindera obtusiloba.

    Science.gov (United States)

    Choi, Eun-Ju; Lee, Soyoung; Kim, Hui-Hun; Singh, Thoudam S K; Choi, Jin Kyeong; Choi, Hyun Gyu; Suh, Won Mo; Lee, Seung-Ho; Kim, Sang-Hyun

    2011-09-01

    The Lindera obtusiloba has been used in traditional medicine for the treatment of inflammation and dermatitis. In this study, we investigated the effect of topical application of Lindera obtusiloba water extract (LOWE) on the house dust mite extract (Dermatophagoides farinae extract, DFE) and 2,4-dinitrochlorobenzene (DNCB)-induced atopic dermatitis (AD). We established AD model in BALB/c mice by repeated local exposure of DFE/DNCB to the ears. After a topical application of LOWE on the skin lesions, the epidermal thickness, mast cell infiltration, and serum immunoglobulin E (IgE) and histamine were measured. In addition, the gene expression of interleukin (IL)-4, IL-13, IL-31, and tumor necrosis factor (TNF)-α in the ears was assayed. LOWE reduced AD symptoms based on ear thickness, histopathological analysis, and serum IgE levels. LOWE inhibited mast cell infiltration into the ear and elevation of serum histamine in AD model. Moreover, LOWE suppressed DFE/DNCB-induced expression of IL-4, IL-13, IL-31, and TNF-α in the ears. Our results showed that topical application of LOWE exerts beneficial effects in AD symptoms, suggesting that LOWE might be a candidate for the treatment of AD. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  12. The Hot-Water Extract of Smilacis Chinae Rhizome Suppresses 2,4-Dinitrochlorobenzene and House Dust Mite-Induced Atopic Dermatitis-Like Skin Lesions in Mice.

    Science.gov (United States)

    Ki, Nam Yong; Park, Eun-Ji; Sung, In sung; Ju, Seul A; Kim, Kyoung Un; Kim, Mi Rae; Song, Do Yeon; Lee, Min-Ju; Kim, Hak-Soo; Kang, Boo-Hyon; Chung, Hun-Jong; Choi, Eun-Ju; Yoon, Ki-Hun; Lee, Min Won; Yun, Seongho; Min, Bokkee; Kwon, Suk Hyung; Shin, Hwa-Sup

    2016-04-01

    Smilacis Chinae Rhizome (SCR) has been used as an oriental folk medicine for various biological activities. However, its effect on atopic dermatitis (AD) remains undetermined to date. We assessed the effect of orally administered hot-water extract of SCR on AD-like skin lesions in mice and its underlying mechanisms. AD-like murine model was prepared by repeated alternate application of house dust mite (Dermatophagoides farinae) extract (DFE) and 2,4-dinitrochlorobenzene (DNCB) for 4 weeks, topically to the ears. Daily oral administration of SCR for 3 and 4 weeks significantly reduced inflammatory ear thickening, with the effect being enhanced at the earlier start and longer period of administration. This effect was accompanied by a significant decrease in both Th2 and Th1 serum antibodies (total IgE, DFE-specific IgE, and IgG2a). Histological analysis showed that SCR markedly decreased the epidermal/dermal ear thickening and the dermal infiltration of inflammatory cells. Furthermore, SCR suppressed DFE/DNCB-induced expression of IL-4, IL-13, IL-17, IL-18, TSLP, and IFN-γ genes in the ear tissue. Taken together, our observations demonstrate that chronic oral administration of SCR exerts beneficial effect in mouse AD model, suggesting that SCR has the therapeutic potential as an orally active treatment of AD by modulating both Th1 and Th2 responses. Copyright © 2016 John Wiley & Sons, Ltd.

  13. Effective mitigation efforts to reduce road dust near industrial sites: assessment by mobile pollution surveys.

    Science.gov (United States)

    DeLuca, Patrick F; Corr, Denis; Wallace, Julie; Kanaroglou, Pavlos

    2012-05-15

    Assessment of spatial variation of fugitive dust sources, particularly road dust track-out from industrial sites and its subsequent re-suspension is difficult with fixed air quality monitoring stations given their sparse distribution and the highly localized nature of road dust. Mobile monitoring was employed to measure levels of road dust in the industrial area of the City of Hamilton, Ontario, Canada. Results of this monitoring were used in a Fugitive Dust Control workshop held for local stakeholders, where fugitive dust control solutions were presented. After the workshop, the City of Hamilton and cooperative industrial groups executed enhanced street cleaning and individual industries and facilities performed on-site control activities. Post-workshop mobile air monitoring was performed for comparison to the initial values to determine effectiveness of these approaches. A regression model testing the difference pre- and post-workshop yielded a statistically significant difference in PM(10) measurements demonstrating improvement. The average value of PM(10) prior to the workshop was 114 μg/m(3). Post-workshop the average value dropped to 73 μg/m(3). Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Puff models for simulation of fugitive radioactive emissions in atmosphere

    International Nuclear Information System (INIS)

    Costa, Camila P. da; Vilhena, Marco T.

    2009-01-01

    A puff model for the dispersion of material from fugitive radioactive emissions is presented. For vertical diffusion the model is based on general techniques for solving time dependent advection-diffusion equation: the ADMM (Advection Diffusion Multilayer Method) and GILTT (Generalized Integral Laplace Transform Technique) techniques. The first one is an analytical solution based on a discretization of the Atmospheric Boundary Layer (ABL) in sub-layers where the advection-diffusion equation is solved by the Laplace transform technique. The solution is given in integral form. The second one is a well-known hybrid method that had solved a wide class of direct and inverse problems mainly in the area of Heat Transfer and Fluid Mechanics and the solution is given in series form. Comparisons between values predicted by the models against experimental ground-level concentrations are shown. (author)

  15. Measurement and Modeling of Fugitive Dust from Off Road DoD Activities

    Science.gov (United States)

    2017-12-08

    D, Suite 200 Ft. Collins, CO 80526 Principle Investigators: Drs. John Tatarko, Michael Wojcik, and Ronaldo Maghirang John.Tatarko...ars.usda.gov Report Authors: Larry Wagner, Michael Wojcik, Fred Fox, John Tatarko, and Ronaldo Maghirang ii Table of Contents Table of Contents...which essentially left previously buried soil on the trafficked surface. The displaced soil created significant (measurable) ridges outside the

  16. Ensemble classification for identifying neighbourhood sources of fugitive dust and associations with observed PM10

    CSIR Research Space (South Africa)

    Khuluse-Makhanya, Sibusisiwe A

    2017-10-01

    Full Text Available residential, townships NE of station Newtown JHB CBD, mining south of station, 73 534 0.12 313 (Traf, JHB) suburbs N of station Tembisa Township, sport fields with bare areas, 42 188 0.07 180 (Dom, Ekurhuleni) unpaved sidewalks and roads Total 634 628 1 2 701... expressed as a percentage are Newton (64%), Pretoria West (65.1%) and Tembisa (66.3%). Therefore these neighbour- hoods are considered to be continuous urban areas in this study. The others are considered to be areas with discontinuous urban fabric. In all...

  17. Baselining Fugitive and Vented Emissions Across Canadian Energy Developments

    Science.gov (United States)

    O'Connell, L.; Risk, D. A.; Fougère, C. R.; Atherton, E.; Baillie, J.; Marshall, A. D.

    2017-12-01

    Nearly half of Alberta's oil and gas related methane emissions are due to fugitives and leaks, which pose significant potential for mitigation. Accurate and spatially-extensive emissions data can help operators and regulators meet reduction targets, and highlight which infrastructure requires immediate attention. This study used a vehicle-based gas monitoring system to detect and quantify methane emissions across large geographic areas in real-time. Our objectives were to quantify methane mixing ratios, determine the drivers of emission variation across several developments, and to evaluate emissions frequency and severity from several thousand wells and facilities. We measured fugitive, un-combusted flaring, and vented emissions within Lloydminster (heavy oil), Peace River (heavy oil), and Medicine Hat (conventional gas), Alberta during fall 2016. During this time, CO2, CH4, H2S, C2H6, and δ13CH4 (Picarro 2210 and Teledyne T101) were recorded from public roads at 1 Hz intervals, collecting over 6.7 million unique measurements in total. Methane anomalies were generally mild (0.2-0.5 ppm) in Peace River and Medicine Hat, but in Lloydminster, CH4 mixing ratios were elevated, and at their worst exceeded 6 ppm over 60 km of driving. We classified oil and gas related plumes based on geochemical emission signatures, and attributed the plumes based on wind direction and proximity to one of the >3200 infrastructural sources we surveyed during the triplicated campaign routes. The relative gas ratios (C1:C2, CO2:CH4) and isotopic signatures of plumes were within expected ranges for each development. Emission frequencies differed amongst developments, but were highest in Lloydminster, where 56% of wells were emitting methane-rich gas above our minimum detection limits. In Medicine Hat and Peace River, 28% and 29% of active wells were tagged as potential emission sources, respectively. Although active wells were the predominant source of emissions, other classes of

  18. Wood Dust

    Science.gov (United States)

    Learn about wood dust, which can raise the risk of cancers of the paranasal sinuses and nasal cavity. High amounts of wood dust are produced in sawmills, and in the furniture-making, cabinet-making, and carpentry industries.

  19. Fugitive carbon dioxide: It's not hiding in the ocean

    International Nuclear Information System (INIS)

    Kerr, R.A.

    1992-01-01

    The fugitive carbon is the difference between the 7 billion or so tons that spew as carbon dioxide from smokestacks and burning tropical forests and the 3.4 billion tons known to stay in the atmosphere. Finding the other 3 billion or 4 billion tons has frustrated researchers for the past 15 years. The oceans certainly take up some of it. Any forecast of global warming has to be based on how much of the carbon dioxide released by human activity will remain in the atmosphere, and predictions vary by 30% depending on the mix of oceanic and terrestrial processes assumed to be removing the gas. What's more, those predictions assume that the processes at work today will go on operating. But not knowing where all the carbon is going raises the unnerving possibility that whatever processes are removing it may soon fall down on the job without warning, accelerating any warming. Such concerns add urgency to the question of whether the ocean harbors the missing carbon. But there's no simple way to find out. The obvious strategy might seem to be to measure the carbon content of the ocean repeatedly to see how much it increases year by year. The trouble is that several billion tons of added carbon, though impressive on a human scale, are undetectable against the huge swings in ocean carbon that occur from season to season, year to year, and place to place

  20. Highly Stretchable, Biocompatible, Striated Substrate Made from Fugitive Glue

    Directory of Open Access Journals (Sweden)

    Wei Li

    2015-06-01

    Full Text Available We developed a novel substrate made from fugitive glue (styrenic block copolymer that can be used to analyze the effects of large strains on biological samples. The substrate has the following attributes: (1 It is easy to make from inexpensive components; (2 It is transparent and can be used in optical microscopy; (3 It is extremely stretchable as it can be stretched up to 700% strain; (4 It can be micro-molded, for example we created micro-ridges that are 6 μm high and 13 μm wide; (5 It is adhesive to biological fibers (we tested fibrin fibers, and can be used to uniformly stretch those fibers; (6 It is non-toxic to cells (we tested human mammary epithelial cells; (7 It can tolerate various salt concentrations up to 5 M NaCl and low (pH 0 and high (pH 14 pH values. Stretching of this extraordinary stretchable substrate is relatively uniform and thus, can be used to test multiple cells or fibers in parallel under the same conditions.

  1. Raising Dust

    Science.gov (United States)

    2004-01-01

    21 December 2003Dust storms are a common occurrence on the extremely arid planet, Mars. However, very rarely do we get to see the actual process of dust being lifted off the martian surface to feed these dust storms. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image captures some of the dust-raising process in action. The picture shows a shallow trough with large, ripple-like dunes on its floor. Sunlight illuminates the scene from the upper left. Puffy, billowy clouds of dust obscure some of the surface from view. Closer inspection shows streamers of dust, streaking from left/upper left toward right/lower right, down near the surface of the planet. It is in these streamers that dust is being lifted from the ground. This image is located near 29.6oS, 73.1oW, and covers an area 3 km (1.9 mi) wide.

  2. Austrian emission inventory for dust

    International Nuclear Information System (INIS)

    Winiwarter, W.; Trenker, C.; Hoeflinger, W.

    2001-09-01

    For the first time, Austrian emissions of anthropogenic particulate matter emissions to the atmosphere have been estimated. Results have been reported as total suspended particles (TSP) as well as for the fractions of particles smaller than 10 μm or 2.5 μm aerodynamic diameter (PM 10 , PM 2.5 ), respectively. Base years for the inventory were 1990, 1995 and 1999. Excluded from this assessment is wind blown dust, which has been considered a natural source here. National statistics have been applied, specifically those also used previously in the Austrian air pollution inventory (OLI). Emission factors have been taken from literature compilations, only for exceptional cases specific Austrian assessments were performed or original literature on emission measurements was consulted. Resuspension of dust by road traffic emerged as the most important source. For the size fraction of PM 10 this source contributed about half of the emissions, when applying the calculation scheme by the U.S. EPA. While this scheme is widely used and well documented, its validity is currently subject of intense scientific debate. As these results do not seem to coincide with ambient air measurements, resuspension of road dust is considered separately and not now included in the national total. The sum of all other sources increases from 75,000 t of TSP in 1990 and 1995 to 77,000 t in 1999, while both PM 10 and PM 2.5 exhibit decreasing tendency (at 45,000 t and 26,000 t in 1999, respectively). The increase in TSP derives from increasing traffic and friction related emissions (tire wear, break wear), decrease of the finer particulate matter is due to reductions in firewood consumption for domestic heating. Most important source sectors are fugitive emissions from material transfer in industry as well as the building industry and the tilling of agricultural land. Common to these sources is the high uncertainty of available data. Wood combustion is the most important of the non-fugitive

  3. Cometary Dust

    Science.gov (United States)

    Levasseur-Regourd, Anny-Chantal; Agarwal, Jessica; Cottin, Hervé; Engrand, Cécile; Flynn, George; Fulle, Marco; Gombosi, Tamas; Langevin, Yves; Lasue, Jérémie; Mannel, Thurid; Merouane, Sihane; Poch, Olivier; Thomas, Nicolas; Westphal, Andrew

    2018-04-01

    This review presents our understanding of cometary dust at the end of 2017. For decades, insight about the dust ejected by nuclei of comets had stemmed from remote observations from Earth or Earth's orbit, and from flybys, including the samples of dust returned to Earth for laboratory studies by the Stardust return capsule. The long-duration Rosetta mission has recently provided a huge and unique amount of data, obtained using numerous instruments, including innovative dust instruments, over a wide range of distances from the Sun and from the nucleus. The diverse approaches available to study dust in comets, together with the related theoretical and experimental studies, provide evidence of the composition and physical properties of dust particles, e.g., the presence of a large fraction of carbon in macromolecules, and of aggregates on a wide range of scales. The results have opened vivid discussions on the variety of dust-release processes and on the diversity of dust properties in comets, as well as on the formation of cometary dust, and on its presence in the near-Earth interplanetary medium. These discussions stress the significance of future explorations as a way to decipher the formation and evolution of our Solar System.

  4. Suppressive effect of an aqueous extract of Diospyros kaki calyx on dust mite extract/2,4-dinitrochlorobenzene-induced atopic dermatitis-like skin lesions.

    Science.gov (United States)

    Yu, Ju-Hee; Jin, Meiling; Choi, Young-Ae; Jeong, Na-Hee; Park, Jeong-Sook; Shin, Tae-Yong; Kim, Sang-Hyun

    2017-08-01

    Atopic dermatitis (AD) is a common chronic inflammatory skin disease, affecting 10-20% of individuals worldwide. Therefore, the discovery of drugs for treating AD is an attractive subject and important to human health. Diospyros kaki and Diospyros kaki (D. kaki) folium exert beneficial effects on allergic inflammation. However, the effect of D. kaki calyx on AD remains elusive. The present study evaluated the effects of an aqueous extract of D. kaki calyx (AEDKC) on AD-like skin lesions using mouse and keratinocyte models. We used a mouse AD model by the repeated skin exposure of house dust mite extract [Dermatophagoides farinae extract (DFE)] and 2,4-dinitrochlorobenzene (DNCB) to the ears. In addition, to determine the underlying mechanism of its operation, tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ)-activated keratinocytes (HaCaT) were used. Oral administration of AEDKC decreased AD-like skin lesions, as demonstrated by the reduced ear thickness, serum immunoglobulin E (IgE), DFE-specific IgE, IgG2a, histamine level and inflammatory cell infiltration. AEDKC inhibited the expression of pro-inflammatory cytokines and a chemokine via downregulation of nuclear factor-κB and signal transducer and activator of transcription 1 in HaCaT cells. On examination of the AD-related factors in vivo and in vitro, it was confirmed that AEDKC decreased AD-like skin lesions. Taken together, the results suggest that AEDKC is a potential drug candidate for the treatment of AD.

  5. OPEN PATH TUNABLE DIODE LASER ABSORPTION SPECTROSCOPY FOR ACQUISITION OF FUGITIVE EMISSION FLUX DATA

    Science.gov (United States)

    Air pollutant emission from unconfined sources is an increasingly important environmental issue. The U.S. EPA has developed a gorund-based optical remote sensing method that enables direct measurement of fugitive emission flux from large area sources. Open-path Fourier transfor...

  6. 77 FR 19153 - Nonpayment of Benefits to Fugitive Felons and Probation or Parole Violators

    Science.gov (United States)

    2012-03-30

    ... Nonpayment of Benefits to Fugitive Felons and Probation or Parole Violators AGENCY: Social Security... 21235-6401, (410) 965-7102. For information on eligibility or filing for benefits, call our national toll-free number, 1-800-772-1213 or TTY 1-800-325-0778, or visit our Internet site, Social Security...

  7. CHARACTERIZATION OF THE FUGITIVE MERCURY EMISSIONS AT A CHLOR-ALKALI PLANT. OVERALL STUDY DESIGN

    Science.gov (United States)

    The paper discusses a detailed emissions measurement campaign that was conducted over a 9-day period within a mercury (Hg) cell chlor-alkali plant in the southeastern United States (U.S.). The principal focus of this study was to measure fugitive (non-ducted) airborne Hg emission...

  8. PROBLEMS WITH DETERMINATION OF FUGITIVE EMISSION OF POLYCYCLIC AROMATIC HYDROCARBONS FROM COKE OVEN BATTERY

    Directory of Open Access Journals (Sweden)

    Rafał Bigda

    2017-03-01

    Full Text Available Coke oven battery is complex and multifaceted facility in terms of air pollutant emissions. As far as stack or quenching tower does not cause major difficulties of emission measurement, the fugitive emission measurement from sources such as battery top elements (charging holes, ascension pipes or oven doors is still complicated and not fully solved problem. This article presents the discussion concerning main problems and errors likely to be made in particular stages of procedure of fugitive emissions characterization from coke oven battery (selection of sampling points, sampling itself, measurement of air velocity over battery top and laboratory analyses. In addition, results of concentrations measurements of selected substances characteristic for the coking process (naphthalene, anthracene, 4 PAHs and TSP originating from fugitive sources of coke oven battery and subjected to reporting under the E-PRTR are presented. The measurements were carried out on coke oven battery top in points selected on the basis of the preceding detailed air convection velocity measurements over battery top. Results of the velocity measurements were compared with results of numerical modelling using CFD software. The presented material is an attempt to cross-sectional presentation of issues related to the quantitative evaluation of fugitive emission from coke oven battery, discussed on the example of PAHs emission as a group of substances characteristic for coking of coal.

  9. Monitoring fugitive methane and natural gas emissions, validation of measurement techniques.

    Science.gov (United States)

    Robinson, Rod; Innocenti, Fabrizio; Gardiner, Tom; Helmore, Jon; Finlayson, Andrew; Connor, Andy

    2017-04-01

    The detection and quantification of fugitive and diffuse methane emissions has become an increasing priority in recent years. As the requirements for routine measurement to support industry initiatives increase there is a growing requirement to assess and validate the performance of fugitive emission measurement technologies. For reported emissions traceability and comparability of measurements is important. This talk will present recent work addressing these needs. Differential Absorption Lidar (DIAL) is a laser based remote sensing technology, able to map the concentration of gases in the atmosphere and determine emission fluxes for fugitive emissions. A description of the technique and its application for determining fugitive emissions of methane from oil and gas operations and waste management sites will be given. As DIAL has gained acceptance as a powerful tool for the measurement and quantification of fugitive emissions, and given the rich data it produces, it is being increasingly used to assess and validate other measurement approaches. In addition, to support the validation of technologies, we have developed a portable controlled release facility able to simulate the emissions from area sources. This has been used to assess and validate techniques which are used to monitor emissions. The development and capabilities of the controlled release facility will be described. This talk will report on recent studies using DIAL and the controlled release facility to validate fugitive emission measurement techniques. This includes side by side comparisons of two DIAL systems, the application of both the DIAL technique and the controlled release facility in a major study carried out in 2015 by South Coast Air Quality Management District (SCAQMD) in which a number of optical techniques were assessed and the development of a prototype method validation approach for techniques used to measure methane emissions from shale gas sites. In conclusion the talk will provide an

  10. Evidence of mineral dust altering cloud microphysics and precipitation

    Directory of Open Access Journals (Sweden)

    Q.-L. Min

    2009-05-01

    Full Text Available Multi-platform and multi-sensor observations are employed to investigate the impact of mineral dust on cloud microphysical and precipitation processes in mesoscale convective systems. For a given convective strength, small hydrometeors were more prevalent in the stratiform rain regions with dust than in those regions that were dust free. Evidence of abundant cloud ice particles in the dust sector, particularly at altitudes where heterogeneous nucleation of mineral dust prevails, further supports the observed changes of precipitation. The consequences of the microphysical effects of the dust aerosols were to shift the precipitation size spectrum from heavy precipitation to light precipitation and ultimately suppressing precipitation.

  11. Impact of fugitive bitumen on polymer-based flocculation of mature fine tailings

    OpenAIRE

    Klein, C; Harbottle, D; Alagha, L; Xu, Z

    2013-01-01

    In bitumen recovery from oil sands, a percentage of the bitumen is lost to tailings. The effect of fugitive bitumen on fines settling and consolidation in tailings ponds remains controversial. In the current study, the settling performance of mature fine tailings (MFT) in response to flocculant addition was considered by studying MFT of varying bitumen content. Bitumen content in the MFT was adjusted by controlled removal of bitumen using a Denver flotation cell. The initial settling rate of ...

  12. On the source inversion of fugitive surface layer releases. Part II. Complex sources

    Science.gov (United States)

    Sanfélix, V.; Escrig, A.; López-Lilao, A.; Celades, I.; Monfort, E.

    2017-06-01

    The experimental measurement of fugitive emissions of particulate matter entails inherent complexity because they are usually discontinuous, of short duration, may be mobile, and are affected by weather conditions. Owing to this complexity, instead of experimental measurements, emission factors are used to inventory such emissions. Unfortunately, emission factor datasets are still very limited at present and are insufficient to identify problematic operations and appropriately select control measures. To extend these datasets, a source inversion methodology (described in Part I of this work) was applied to field campaigns in which operation-specific fugitive particulate matter emission factors were determined for several complex fugitive sources, some of which were mobile. Mobile sources were treated as a superposition of instantaneous sources. The experimental campaigns were conducted at ports (bulk solids terminals), aggregate quarries, and cement factories, encompassing powder handling operations and vehicle circulation on paved and unpaved roads. Emission factors were derived for the operations and materials involved in these scenarios and compared with those available in the emission factor compilations. Significant differences were observed between the emission factors obtained in the studied handling operations. These differences call into question the use of generic emission factors and highlight the need for more detailed studies in this field.

  13. Determination of road dust loadings and chemical characteristics using resuspension.

    Science.gov (United States)

    Chen, Jianhua; Wang, Wei; Liu, Hongjie; Ren, Lihong

    2012-03-01

    The contribution of fugitive dust from traffic to air pollution can no longer be ignored in China. In order to obtain the road dust loadings and to understand the chemical characteristics of PM(10) and PM(2.5) from typical road dust, different paved roads in eight districts of Beijing were selected for dust collection during the four seasons of 2005. Ninety-eight samples from 28 roads were obtained. The samples were resuspended using equipment assembled to simulate the rising process of road dust caused by the wind or wheels in order to obtain the PM(10) and PM(2.5) filter samples. The average road dust loading was 3.82 g m(-2), with the highest of 24.22 g m(-2) being in Hutongs in the rural-urban continuum during winter. The road dust loadings on higher-grade roads were lower than those on lower-grade roads. Attention should be paid to the pollution in the rural-urban continuum areas. The sums of element abundances measured were 16.17% and 18.50% for PM(10) and PM(2.5) in road dust. The average abundances of OC and EC in PM(10) and PM(2.5) in road dust were 11.52%, 2.01% and 12.50%, 2.06%, respectively. The abundance of elements, water-soluble ions, and OC, EC in PM(10) and PM(2.5) resuspended from road dust did not change greatly with seasons and road types. The soil dust, construction dust, dust emitted from burning coal, vehicle exhaust, and deposition of particles in the air were the main sources of road dust in Beijing. Affected by the application of snow-melting agents in Beijing during winter, the amount of Cl( - ) and Na( + ) was much higher during that time than in the other seasons. This will have a certain influence on roads, bridges, vegetations, and groundwater.

  14. Dust emissions from unpaved roads on the Colorado Plateau

    Science.gov (United States)

    Duniway, M.; Flagg, C.; Belnap, J.

    2013-12-01

    On the Colorado Plateau, elevated levels of aeolian dust have become a major land management and policy concern due to its influence on climate, weather, terrestrial ecosystem dynamics, landscape development and fertility, melting of snow and ice, air quality, and human health. Most desert soil surfaces are stabilized by plants, rocks, and/or physical or biological soil crusts, but once disturbed, sediment production from these surfaces can increase dramatically. Road development and use is a common surface disturbing activity in the region. The extent and density of roads and road networks is rapidly increasing due to continued energy exploration, infrastructure development, and off-highway recreation activities. Though it is well known that unpaved roads produce dust, the relative contribution of dust from existing roads or the implications of future road development to regional dust loading is unknown. To address this need, we have initiated a multifaceted research effort to evaluating dust emissions from unpaved roads regionally. At 34 sites arranged across various road surfaces and soil textures in southeastern Utah, we are: 1) monitoring dust emissions, local wind conditions, and vehicle traffic and 2) evaluating fugitive dust potential using a portable wind tunnel and measuring road characteristics that affect dust production. We will then 3) develop a GIS-based model that integrates results from 1 & 2 to estimate potential dust contributions from current and future scenarios of regional road development. Passive, horizontal sediment traps were installed at three distances downwind from the road edge. One control trap was placed upwind of the samplers to account for local, non-road dust emissions. An electronic vehicle counter and anemometer were also installed at monitoring sites. Dust samples were collected every three months at fixed heights, 15 cm up to 100 cm above the soil surface, from March 2010 to the present. Threshold friction velocities (TFV

  15. Surface renewal as a significant mechanism for dust emission

    Directory of Open Access Journals (Sweden)

    J. Zhang

    2016-12-01

    Full Text Available Wind tunnel experiments of dust emissions from different soil surfaces are carried out to better understand dust emission mechanisms. The effects of surface renewal on aerodynamic entrainment and saltation bombardment are analyzed in detail. It is found that flow conditions, surface particle motions (saltation and creep, soil dust content and ground obstacles all strongly affect dust emission, causing its rate to vary over orders of magnitude. Aerodynamic entrainment is highly effective, if dust supply is unlimited, as in the first 2–3 min of our wind tunnel runs. While aerodynamic entrainment is suppressed by dust supply limits, surface renewal through the motion of surface particles appears to be an effective pathway to remove the supply limit. Surface renewal is also found to be important to the efficiency of saltation bombardment. We demonstrate that surface renewal is a significant mechanism affecting dust emission and recommend that this mechanism be included in future dust models.

  16. Salt Efflorescence Effects on Soil Surface Erodibility and Dust Emissions

    Science.gov (United States)

    Van Pelt, R. S.; Zhang, G.

    2017-12-01

    Soluble salts resulting from weathering of geological materials often form surface crusts or efflorescences in areas with shallow saline groundwater. In many cases, the affected areas are susceptible to wind erosion due to their lack of protective vegetation and their flat topography. Fugitive dusts containing soluble salts affect the biogeochemistry of deposition regions and may result in respiratory irritation during transport. We created efflorescent crusts on soil trays by surface evaporation of single salt solutions and bombarded the resultant efflorescences with quartz abrader sand in a laboratory wind tunnel. Four replicate trays containing a Torrifluvent soil affected by one of nine salts commonly found in arid and semiarid streams were tested and the emissions were captured by an aspirated multi-stage deposition and filtering system. We found that in most cases the efflorescent crust reduced the soil surface erodibility but also resulted in the emission of salt rich dust. Two of the salts, sodium thiosulfate and calcium chloride, resulted in increased soil volume and erodibility. However, one of the calcium chloride replicates was tested after an outbreak of humid air caused hygroscopic wetting of the soil and it became indurated upon drying greatly decreasing the erodibility. Although saline affected soils are not used for agricultural production and degradation is not a great concern, the release of salt rich dust is an area of environmental concern and steps to control the dust emissions from affected soils should be developed. Future testing will utilize suites of salts found in streams of arid and semiarid regions.

  17. Connecting the Plots: The Extension of Return and Korean Ethnic Nationalism in Jane Jeong Trenka’s 'Fugitive Visions'

    OpenAIRE

    Waddell, Ethan

    2017-01-01

    Thousands of overseas Korean adoptees return to Korea temporarily each year in search of their true origin, but few choose to stay permanently. A prominent member of this small community is Jane Jeong Trenka, author of two memoirs: The Language of Blood (2003) and Fugitive Visions: An Adoptee’s Return to Korea (2009). This article analyses Trenka’s literary struggle for permanence in Fugitive Visions through theories on Korean ethnic national identity. Using Marshall McLuhan’s idea of media a...

  18. Fugitive emissions control on dry copper tailing with crushed rock armor

    International Nuclear Information System (INIS)

    Haase, E.F.

    1992-01-01

    Four inactive copper tailing impoundments totalling 1,900 acres near Ajo in southwestern Arizona were covered on horizontal surfaces with a 2 in. nominal thickness of crushed rock to control particulate emissions. The tailings are typically dominated by sand-sized particles but may also include significant PM 10 fractions towards the centers of the impoundments. The technology was selected by Phelps Dodge Corporation, after investigation of several alternatives, as a permanent and practical cover that essentially eliminates fugitive emissions. It simulates the natural desert pavement that characterizes this arid area of the Sonoran Desert. Rocky overburden was crushed to minus 3 in. diameter and broadcast on dry surfaces of tailing impoundments with all-terrain, balloon-tired spreaders. Stony residues in the rock armor tend to cement together following rainfall, forming a crust that enhances surface stability and erosion control. Slopes with windblown tailing deposition were covered to a nominal 6 in. thickness by conventional dozer pushing and blading of minus 10 in. rock over the sides. Athel trees, planted extensively since 1970 on two of the four inactive impoundments, provided partial control of fugitives, but were subjected to harsh environmental conditions, including abrasion from saltating particles. The rock armor functions as a mulch which is expected to improve water relations for existing vegetation and areas seeded with native species. New surface microenvironments, and the virtual elimination of surface creep and saltation, are expected to support native plant growth under favorable climatic conditions

  19. Metaphors of pain: the use of metaphors in trauma narrative with reference to Fugitive pieces

    Directory of Open Access Journals (Sweden)

    J. Anker

    2009-07-01

    Full Text Available This article is a contribution to the recent interdisciplinary discourse between psychoanalysis, trauma theory and narrative by discussing the traumatic experiences of characters in the novel “Fugitive pieces” by Anne Michaels, with a specific focus on the metaphorical style of this novel. The article addresses the role of metaphor in the memory of trauma while comparing the relation between trauma, narrative and memory with reference to the work of Cathy Caruth, Van der Kolk and Margaret Wilkinson. Recent neurobiological research in the working of the brain during trauma and the insights of Borbelly in the role of metaphor during therapy are discussed. Insights of Lacan, Modell and Laplanche are integrated with those of psychologists like Knox, Borbelly and Van der Hart to counter arguments against the criticism brought against some of the metaphorical themes in “Fugitive pieces”. Metaphor is seen as one possible way of saying the inexpressible and the progression in the use of metaphor by patient and character alike is seen as one of the signs of healing from trauma.

  20. [Effect of lunar dust on humans: -lunar dust: regolith-].

    Science.gov (United States)

    Morimoto, Yasuo; Miki, Takeo; Higashi, Toshiaki; Horie, Seichi; Tanaka, Kazunari; Mukai, Chiaki

    2010-09-01

    We reviewed the effect of lunar dust (regolith) on humans by the combination of the hazard/exposure of regolith and microgravity of the moon. With regard to the physicochemical properties of lunar dust, the hazard-related factors are its components, fibrous materials and nanoparticles. Animal exposure studies have been performed using a simulant of lunar dust, and it was speculated that the harmful effects of the simulant lies between those of crystalline silica and titanium dioxide. Fibrous materials may not have a low solubility judging from their components. The nanoparticles in lunar dust may have harmful potentials from the view of the components. As for exposure to regolith, there is a possibility that particles larger than ones in earth (1 gravity) are respirable. In microgravity, 1) the deposition of particles of less than 1 µm in diameter in the human lung did not decrease, 2) the functions of macrophages including phagocytosis were suppressed, 3) pulmonary inflammation was changed. These data on hazard/exposure and microgravity suggest that fine and ultrafine particles in regolith may have potential hazards and risks for humans.

  1. Fugitive emission rates assessment of PM2.5 and PM10 from open storage piles in China

    Science.gov (United States)

    Cao, Yiqi; Liu, Tao; He, Jiao

    2018-03-01

    An assessment of the fugitive emission rates of PM2.5 and PM10 from an open static coal and mine storage piles. The experiment was conducted at a large union steel enterprises in the East China region to effectively control the fugitive particulate emissions pollution on daily work and extreme weather conditions. Wind tunnel experiments conducted on the surface of static storage piles, and it generated specific fugitive emission rates (SERs) at ground level of between ca.10-1 and ca.102 (mg/m2·s) for PM2.5 and between ca.101 and ca.103 (mg/m2·s) for PM10 under the u*(wind velocity) between ca.3.0 (m/s) and 10.0 (m/s). Research results show that SERs of different materials differ a lot. Material particulate that has lower surface moisture content generate higher SER and coal material generate higher SER than mine material. For material storage piles with good water infiltrating properties, aspersion is a very effective measure for control fugitive particulate emission.

  2. CHARACTERIZATION OF FUGITIVE MERCURY EMISSIONS FROM THE CELL BUILDING AT A U.S. CHLOR-ALKALI PLANT

    Science.gov (United States)

    The paper discusses an extensive measurement campaign that was conducted of the fugitive (non-ducted) airborne elemental mercury [Hg(0)] emissions from the cell building of a chlor-alkali plant (CAP) located in the southeastern United States. The objectives of this study were to ...

  3. The impact of dust on sulfate aerosol, CN and CCN during an East Asian dust storm

    Directory of Open Access Journals (Sweden)

    P. T. Manktelow

    2010-01-01

    Full Text Available A global model of aerosol microphysics is used to simulate a large East Asian dust storm during the ACE-Asia experiment. We use the model together with size resolved measurements of aerosol number concentration and composition to examine how dust modified the production of sulfate aerosol and the particle size distribution in East Asian outflow. Simulated size distributions and mass concentrations of dust, sub- and super-micron sulfate agree well with observations from the C-130 aircraft. Modeled mass concentrations of fine sulfate (Dp<1.3 μm decrease by ~10% due to uptake of sulfur species onto super-micron dust. We estimate that dust enhanced the mass concentration of coarse sulfate (Dp>1.0 μm by more than an order of magnitude, but total sulfate concentrations increase by less than 2% because decreases in fine sulfate have a compensating effect. Our analysis shows that the sulfate associated with dust can be explained largely by the uptake of H2SO4 rather than reaction of SO2 on the dust surface, which we assume is suppressed once the particles are coated in sulfate. We suggest that many previous model investigations significantly overestimated SO2 oxidation on East Asian dust, possibly due to the neglect of surface saturation effects. We extend previous model experiments by examining how dust modified existing particle concentrations in Asian outflow. Total particle concentrations (condensation nuclei, CN modeled in the dust-pollution plume are reduced by up to 20%, but we predict that dust led to less than 10% depletion in particles large enough to act as cloud condensation nuclei (CCN. Our analysis suggests that E. Asian dust storms have only a minor impact on sulfate particles present at climate-relevant sizes.

  4. Past, present and future of dust research at the Elliot Lake Laboratory

    International Nuclear Information System (INIS)

    Grenier, M.; Bigu, J.

    1985-12-01

    A brief history of the dust research work at the Elliot Lake Laboratory is given. Two decades of dust research work are studied and reviewed. This review clearly shows where, when, and with what intensity various components of dust research were performed. From the data presented here, it is suggested that a major portion of the future efforts be aimed at research directed towards the control and suppression of dust in underground mines

  5. Independent quality assurance of refinery fugitives testing by western states petroleum association. Final audit report

    Energy Technology Data Exchange (ETDEWEB)

    1993-09-01

    Research Triangle Institute (RTI) undertook this task for the U.S. Environmental Protection Agency's (EPA's) Office of Air Quality Planning and Standards to provide third-party Quality Assurance (QA) support to a Western States' Petroleum Association (WSPA) program to measure fugitive emissions at petroleum refineries. The primary objectives of the WSPA study were to determine the correlation between screening values and true mass emission rates and to develop a relationship between liquid and gas composition. EPA's QA effort, however, focused only on the correlation objective because the number of leaking components in the California refineries cannot be expected to be representative of refineries in general. The number of components leaking at a given screening value is used in conjunction with the mass correlations to derive the average emission factors.

  6. Measurements of industrial fugitive emissions by the FTIR Tracer Method (FTM)

    International Nuclear Information System (INIS)

    Mellqvist, J.; Arlander, B.; Galle, B.; Bergqvist, B.

    1996-01-01

    A new method called the FTIR Tracer Method (FTM), has been developed for measuring and quantifying fugitive (diffuse) emissions of hydrocarbons. The method has been evaluated in field experiments which were conducted in the vicinity of several petrochemical plants and an oil refinery during 1993-1995. The technique is based on concentration measurements with infrared remote sensing by Long Path Fourier Transform InfraRed (LPFTIR), combined with tracer releases. The field experiments show the FTM to be very useful for mass flux measurements of both alkanes and alkenes and that the measurements are consistent with the conventional SF 6 method. However, the technique needs to be further validated and a more thorough understanding of the measurement uncertainties have to be achieved

  7. Fugitive halocarbon emissions from working face of municipal solid waste landfills in China.

    Science.gov (United States)

    Liu, Yanjun; Lu, Wenjing; Dastyar, Wafa; Liu, Yanting; Guo, Hanwen; Fu, Xindi; Li, Hao; Meng, Ruihong; Zhao, Ming; Wang, Hongtao

    2017-12-01

    Halocarbons are important anthropogenic greenhouse gases (GHGs) due to their long lifetime and large characteristic factors. The present study for the first time assessed the global warming potential (GWP) of fugitive halocarbon emissions from the working face of landfills in China. The national emissions of five major halocarbons (CFC-11, CFC-113, CH 2 Cl 2 , CHCl 3 and CCl 4 ) from the working face of municipal solid waste landfills in China were provided through observation-based estimations. The fluxes of halocarbons from working face of landfills were observed much higher than covered cells in landfills hence representing the hot spots of landfill emissions. The annual emissions of the halocarbons from landfills in China were 0.02-15.6kt·y -1 , and their GWPs were 128-60,948kt-CO 2 -eq·y -1 based on their characteristic factors on a 100-year horizon. CFC-113 was the dominant species owing to its highest releasing rate (i.e. 15.4±19.1g·t -1 ) and largest characteristic factor, resulting in a GWP up to 4036±4855kt-CO 2 -eq·y -1 . The annual emissions of CFC-113 from landfills (i.e. 0.61kt·y -1 ) made up ∼76% of the total national CFC-113 emissions. The GWPs of halocarbons were estimated ∼14.4% of landfill methane emissions. Therefore, fugitive halocarbons emissions from working face are significant sources of GHGs in landfill sites in China, although they comprise a small fraction of total landfill gases. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. A new approach to estimate fugitive methane emissions from coal mining in China.

    Science.gov (United States)

    Ju, Yiwen; Sun, Yue; Sa, Zhanyou; Pan, Jienan; Wang, Jilin; Hou, Quanlin; Li, Qingguang; Yan, Zhifeng; Liu, Jie

    2016-02-01

    Developing a more accurate greenhouse gas (GHG) emissions inventory draws too much attention. Because of its resource endowment and technical status, China has made coal-related GHG emissions a big part of its inventory. Lacking a stoichiometric carbon conversion coefficient and influenced by geological conditions and mining technologies, previous efforts to estimate fugitive methane emissions from coal mining in China has led to disagreeing results. This paper proposes a new calculation methodology to determine fugitive methane emissions from coal mining based on the domestic analysis of gas geology, gas emission features, and the merits and demerits of existing estimation methods. This new approach involves four main parameters: in-situ original gas content, gas remaining post-desorption, raw coal production, and mining influence coefficient. The case studies in Huaibei-Huainan Coalfield and Jincheng Coalfield show that the new method obtains the smallest error, +9.59% and 7.01% respectively compared with other methods, Tier 1 and Tier 2 (with two samples) in this study, which resulted in +140.34%, +138.90%, and -18.67%, in Huaibei-Huainan Coalfield, while +64.36%, +47.07%, and -14.91% in Jincheng Coalfield. Compared with the predominantly used methods, this new one possesses the characteristics of not only being a comparably more simple process and lower uncertainty than the "emission factor method" (IPCC recommended Tier 1 and Tier 2), but also having easier data accessibility, similar uncertainty, and additional post-mining emissions compared to the "absolute gas emission method" (IPCC recommended Tier 3). Therefore, methane emissions dissipated from most of the producing coal mines worldwide could be more accurately and more easily estimated. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Assessing fugitive emissions of CH4 from high-pressure gas pipelines in the UK.

    Science.gov (United States)

    Boothroyd, Ian M; Almond, Sam; Worrall, Fred; Davies, Rosemary K; Davies, Richard J

    2018-03-16

    Natural gas pipelines are an important source of fugitive methane emissions in lifecycle greenhouse gas assessments but limited monitoring has taken place of UK pipelines to quantify fugitive emissions. This study investigated methane emissions from the UK high-pressure pipeline system (National Transmission System - NTS) for natural gas pipelines. Mobile surveys of CH 4 emissions were conducted across four areas in the UK, with routes bisecting high-pressure pipelines (with a maximum operating pressure of 85bar) and separate control routes away from the pipelines. A manual survey of soil gas measurements was also conducted along one of the high-pressure pipelines using a tunable diode laser. For the pipeline routes, there were 26 peaks above 2.1ppmv CH 4 at 0.23peaks/km, compared with 12 peaks at 0.11peaks/km on control routes. Three distinct thermogenic emissions were identified on the basis of the isotopic signal from these elevated concentrations with a peak rate of 0.03peaks/km. A further three thermogenic emissions on pipeline routes were associated with pipeline infrastructure. Methane fluxes from control routes were statistically significantly lower than the fluxes measured on pipeline routes, with an overall pipeline flux of 627 (241-1123 interquartile range) tonnes CH 4 /km/yr. Soil gas CH 4 measurements indicated a total flux of 62.6ktCH 4 /yr, which equates to 2.9% of total annual CH4 emissions in the UK. We recommend further monitoring of the UK natural gas pipeline network, with assessments of transmission and distribution stations, and distribution pipelines necessary. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  10. Investigation of Natural Gas Fugitive Leak Detection Using an Unmanned Aerial Vehicle

    Science.gov (United States)

    Yang, S.; Talbot, R. W.; Frish, M. B.; Golston, L.; Aubut, N. F.; Zondlo, M. A.

    2017-12-01

    The U.S is now the world's largest natural gas producer, of which methane (CH4) is the main component. About 2% of the CH4 is lost through fugitive leaks. This research is under the DOE Methane Observation Networks with Innovative Technology to Obtain Reductions (MONITOR) program of ARPA-E. Our sentry measurement system is composed of four state-of-the-art technologies centered around the RMLDTM (Remote Methane Leak Detector). An open path RMLDTM measures column-integrated CH4 concentration that incorporates fluctuations in the vertical CH4 distribution. Based on Backscatter Tunable Diode Laser Absorption Spectroscopy and Small Unmanned Aerial Vehicles, the sentry system can autonomously, consistently and cost-effectively monitor and quantify CH4 leakage from sites associated with natural gas production. This system provides an advanced capability in detecting leaks at hard-to-access sites (e.g., wellheads) compared to traditional manual methods. Automated leak detecting and reporting algorithms combined with wireless data link implement real-time leak information reporting. Early data were gathered to set up and test the prototype system, and to optimize the leak localization and calculation strategies. The flight pattern is based on a raster scan which can generate interpolated CH4 concentration maps. The localization and quantification algorithms can be derived from the plume images combined with wind vectors. Currently, the accuracy of localization algorithm can reach 2 m and the calculation algorithm has a factor of 2 accuracy. This study places particular emphasis on flux quantification. The data collected at Colorado and Houston test fields were processed, and the correlation between flux and other parameters analyzed. Higher wind speeds and lower wind variation are preferred to optimize flux estimation. Eventually, this system will supply an enhanced detection capability to significantly reduce fugitive CH4 emissions in the natural gas industry.

  11. Suppressed Belief

    Directory of Open Access Journals (Sweden)

    Komarine Romdenh-Romluc

    2009-12-01

    Full Text Available Moran’s revised conception of conscious belief requires us to reconceptualise suppressed belief. The work of Merleau-Ponty offers a way to do this. His account of motor-skills allows us to understand suppressed beliefs as pre-reflective ways of dealing with the world.

  12. Dusts and Molds

    Science.gov (United States)

    ... limit your exposure by taking these general measures. Think about how they apply in your setting. • Prevent dusts and molds from forming, e.g. drying feeds and cleaning animal areas regularly. • Prevent dusts and molds from becoming ...

  13. LADEE LUNAR DUST EXPERIMENT

    Data.gov (United States)

    National Aeronautics and Space Administration — This archive bundle includes data taken by the Lunar Dust Experiment (LDEX) instrument aboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft....

  14. Construction dust amelioration techniques.

    Science.gov (United States)

    2012-04-01

    Dust produced on seasonal road construction sites in Alaska is both a traffic safety and environmental concern. Dust emanating from : unpaved road surfaces during construction severely reduces visibility and impacts stopping sight distance, and contr...

  15. Physics of interstellar dust

    CERN Document Server

    Krugel, Endrik

    2002-01-01

    The dielectric permeability; How to evaluate grain cross sections; Very small and very big particles; Case studies of Mie calculus; Particle statistics; The radiative transition probability; Structure and composition of dust; Dust radiation; Dust and its environment; Polarization; Grain alignment; PAHs and spectral features of dust; Radiative transport; Diffuse matter in the Milky Way; Stars and their formation; Emission from young stars. Appendices Mathematical formulae; List of symbols.

  16. Connecting the Plots: The Extension of Return and Korean Ethnic Nationalism in Jane Jeong Trenka’s 'Fugitive Visions'

    Directory of Open Access Journals (Sweden)

    Ethan Waddell

    2017-05-01

    Full Text Available Thousands of overseas Korean adoptees return to Korea temporarily each year in search of their true origin, but few choose to stay permanently. A prominent member of this small community is Jane Jeong Trenka, author of two memoirs: The Language of Blood (2003 and Fugitive Visions: An Adoptee’s Return to Korea (2009. This article analyses Trenka’s literary struggle for permanence in Fugitive Visions through theories on Korean ethnic national identity. Using Marshall McLuhan’s idea of media as the ‘extension of man’, it explores the symbiotic relationship between literary media and identity, connecting colonial-era writings on Korean ethnic nationalism to Trenka’s portrayal of transnational return.

  17. Is Optical Gas Imaging Effective for Detecting Fugitive Methane Emissions? - A Technological and Policy Perspective

    Science.gov (United States)

    Ravikumar, A. P.; Wang, J.; Brandt, A. R.

    2016-12-01

    Mitigating fugitive methane emissions from the oil and gas industry has become an important concern for both businesses and regulators. While recent studies have improved our understanding of emissions from all sectors of the natural gas supply chain, cost-effectively identifying leaks over expansive natural gas infrastructure remains a significant challenge. Recently, the Environmental Protection Agency (EPA) has recommended the use of optical gas imaging (OGI) technologies to be used in industry-wide leak detection and repair (LDAR) programs. However, there has been little to no systematic study of the effectiveness of infrared-camera-based OGI technology for leak detection applications. Here, we develop a physics-based model that simulates a passive infrared camera imaging a methane leak against varying background and ambient conditions. We verify the simulation tool through a series of large-volume controlled release field experiments wherein known quantities of methane were released and imaged from a range of distances. After simulator verification, we analyze the effects of environmental conditions like temperature, wind, and imaging background on the amount of methane detected from a statistically representative survey program. We also examine the effects of LDAR design parameters like imaging distance, leak size distribution, and gas composition. We show that imaging distance strongly affects leak detection - EPA's expectation of a 60% reduction in fugitive emissions based on a semi-annual LDAR survey will be realized only if leaks are imaged at a distance less than 10 m from the source under ideal environmental conditions. Local wind speed is also shown to be important. We show that minimum detection limits are 3 to 4 times higher for wet-gas compositions that contain a significant fraction of ethane and propane, resulting a significantly large leakage rate. We also explore the importance of `super-emitters' on the performance of an OGI-based leak

  18. Monitoring fugitive CH4 and CO2 emissions from a closed landfill at Tenerife, Canary Islands

    Science.gov (United States)

    Asensio-Ramos, María; Tompkins, Mitchell R. K.; Turtle, Lara A. K.; García-Merino, Marta; Amonte, Cecilia; Rodrígez, Fátima; Padrón, Eleazar; Melián, Gladys V.; Padilla, Germán; Barrancos, José; Pérez, Nemesio M.

    2017-04-01

    Solid waste must be managed systematically to ensure environmental best practices. One of the ways to manage this huge problem is to systematic dispose waste materials in locations such as landfills. However, landfills could face possible threats to the environment such as groundwater pollution and the release of landfill gases (CH4, volatile organic compounds, etc.) to the atmosphere. These structures should be carefully filled, monitored and maintained while they are active and for up to 30 years after they are closed. Even after years of being closed, a systematically amount of landfill gas could be released to the atmosphere through its surface in a diffuse and fugitive form. During the period 1999-2016, we have studied the spatial-temporal distribution of the surface fugitive emission of CO2 and CH4 into the atmosphere in a cell in the Arico's municipal landfill (0.3 km2) at Tenerife, Canary Islands, Spain. This cell was operative until 2004, when it was filled and closed. Monitoring these diffuse landfill emissions provides information of how the closed landfill is degassing. To do so, we have performed 9 gas emission surveys during the period 1999-2016. Surface landfill CO2 efflux measurements were carried out at around 450 sampling site by means of a portable non-dispersive infrared spectrophotometer (NDIR) model LICOR Li800 following the accumulation chamber method. Landfill gases taken in the chamber were analyzed using a double channel VARIAN 4900 micro-GC. CH4 efflux measurements were computed combining CO2 efflux measurements and CH4/CO2 ratio in the landfill's surface gas. To quantify the total CH4 emission, CH4 efflux contour map was constructed using sequential Gaussian simulation (sGs) as interpolation method. In general, a decrease in the CO2 emission is observed since the cell was closed (2004) to the present. The total CO2 and CH4 diffuse emissions estimated in the 2016 survey were 4.54 ± 0.14 t d-1 and 268.65 ± 17.99 t d-1, respectively

  19. Interstellar Dust - A Review

    Science.gov (United States)

    Salama, Farid

    2012-01-01

    The study of the formation and the destruction processes of cosmic dust is essential to understand and to quantify the budget of extraterrestrial organic materials. Although dust with all its components plays an important role in the evolution of interstellar physics and chemistry and in the formation of organic materials, little is known on the formation and destruction processes of carbonaceous dust. Laboratory experiments that are performed under conditions that simulate interstellar and circumstellar environments to provide information on the nature, the size and the structure of interstellar dust particles, the growth and the destruction processes of interstellar dust and the resulting budget of extraterrestrial organic molecules. A review of the properties of dust and of the laboratory experiments that are conducted to study the formation processes of dust grains from molecular precursors will be given.

  20. Coagulation of charged particles in dust plasma

    International Nuclear Information System (INIS)

    Belov, I.A.; Ivanov, A.S.; Ivanov, D.A.; Pal', A.F.; Starostin, A.N.; Filippov, A.V.; Dem'yanov, A.V.; Petrushevich, Yu.V.

    2000-01-01

    One studied peculiarities of behaviour of small particles in dust plasma resulted on the one hand, from suppression of coagulation due to monopolar charging within the range of particle dimensions under the Debye radius of shielding and, on the other hand, from leveling of this case for particles of large dimensions. On the basis of similarity ratios one determined the range of parameters making linear approximation of particle charge dependence on their dimension true. In terms of the modified classical theory of coagulation in diffusion approximation one studied certain anomalies of behavior of dimension distribution of particles. It is determined that in contrast to the ordinary aerosol in dust plasma as time passes one may reduce dispersion of distribution and average dimensions of particles. For the first time one demonstrates the possibility to realize long-lived quasiliquid state of dust plasma associated with the anomalous behaviour of distribution function of coagulating charged particles according to dimensions [ru

  1. Fugitive methane emissions from leak-prone natural gas distribution infrastructure in urban environments.

    Science.gov (United States)

    Hendrick, Margaret F; Ackley, Robert; Sanaie-Movahed, Bahare; Tang, Xiaojing; Phillips, Nathan G

    2016-06-01

    Fugitive emissions from natural gas systems are the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S. and contribute to the risk of explosions in urban environments. Here, we report on a survey of CH4 emissions from 100 natural gas leaks in cast iron distribution mains in Metro Boston, MA. Direct measures of CH4 flux from individual leaks ranged from 4.0 - 2.3 × 10(4) g CH4•day(-1). The distribution of leak size is positively skewed, with 7% of leaks contributing 50% of total CH4 emissions measured. We identify parallels in the skewed distribution of leak size found in downstream systems with midstream and upstream stages of the gas process chain. Fixing 'superemitter' leaks will disproportionately stem greenhouse gas emissions. Fifteen percent of leaks surveyed qualified as potentially explosive (Grade 1), and we found no difference in CH4 flux between Grade 1 leaks and all remaining leaks surveyed (p = 0.24). All leaks must be addressed, as even small leaks cannot be disregarded as 'safely leaking.' Key methodological impediments to quantifying and addressing the impacts of leaking natural gas distribution infrastructure involve inconsistencies in the manner in which gas leaks are defined, detected, and classified. To address this need, we propose a two-part leak classification system that reflects both the safety and climatic impacts of natural gas leaks. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Practical Design Guidelines for Fugitive Gas Detection from Unmanned Aerial Vehicles

    Science.gov (United States)

    Tandy, William D., Jr.

    Simulation, design, and analysis are combined in this effort to realize a UAV-scale instrument for fugitive gas detection. The contributing material to the industry begins by extending and correlating an integrated Gaussian plume model useful for instrument predictions and trade studies, regardless of the instrument type or molecule of interest. A variety of generally applicable plots are produced from this foundation, including receiver operator curves for leak rate detectability vs. wind speed, beam diameter vs. leak rate detectability, and plots for required scan densities. The atmospheric and instrument parameter trade studies are followed by hardware-specific analyses applicable to differential absorption lidar (DIAL) instruments. A synopsis of the lessons learned from hands-on experiences in the lab further define the design space for DIAL sensors. The dissertation culminates in the detailed design and analysis of two DIAL instrument concepts. The conclusion is that a DIAL instrument capable of reliably detecting a 50 SCFH plume in winds speeds up to 7 mph is on the threshold of being achievable on a quadcopter platform. Of special note is that the effort was funded by a Pipeline and Hazardous Materials Safety Administration grant and performed in collaboration with Ball Aerospace & Technologies.

  3. Assessment for potential radionuclide emissions from stacks and diffuse and fugitive sources on the Hanford Site

    International Nuclear Information System (INIS)

    Davis, W.E.; Schmidt, J.W.; Gleckler, B.P.; Rhoads, K.

    1995-06-01

    By using the six EPA-approved methods, instead of only the original back calculation method for assessing the 84 WHC registered stacks, the number of stacks requiring continuous monitoring was reduced from 32 to 19 stacks. The intercomparison between results showed that no correlation existed between back calculations and release fractions. Also the NDA, upstream air samples, and powder release fraction method results were at least three orders of magnitude lower then the back calculations results. The most surprising results of the assessment came from NDA. NDA was found to be an easy method for assessing potential emissions. For the nine stacks assessed by NDA, all nine of the stacks would have required continuous monitoring when assessed by back calculations. However, when NDA was applied all stacks had potential emissions that would cause an EDE below the > 0.1 mrem/y standard. Apparent DFs for the HEPA filter systems were calculated for eight nondesignated stacks with emissions above the detection limit. These apparent DFs ranged from 0.5 to 250. The EDE dose to the MEI was calculated to be 0.028 mrem/y for diffuse and fugitive emissions from the Hanford Sited. This is well below the > 0.1 mrem/y standard

  4. Star formation suppression in compact group galaxies

    DEFF Research Database (Denmark)

    Alatalo, K.; Appleton, P. N.; Lisenfeld, U.

    2015-01-01

    We present CO(1-0) maps of 12 warm H-2-selected Hickson Compact Groups (HCGs), covering 14 individually imaged warm H2 bright galaxies, with the Combined Array for Research in Millimeter Astronomy. We found a variety of molecular gas distributions within the HCGs, including regularly rotating disks......, bars, rings, tidal tails, and possibly nuclear outflows, though the molecular gas morphologies are more consistent with spirals and earlytype galaxies than mergers and interacting systems. Our CO-imaged HCG galaxies, when plotted on the Kennicutt-Schmidt relation, shows star formation (SF) suppression......-to-dust ratios of these galaxies to determine if an incorrect LCO-M(H2) conversion caused the apparent suppression and find that HCGs have normal gas-to-dust ratios. It is likely that the cause of the apparent suppression in these objects is associated with shocks injecting turbulence into the molecular gas...

  5. Dust in Libraries

    OpenAIRE

    Mašková, Ludmila

    2013-01-01

    Indoor air pollution in libraries and archives can be harmful for materials stored there. Adverse effects of most of gaseous pollutants are well described, but less is known about dust. Dust particles cover a wide range of sizes and have a variable composition. These characteristics determine their transport to the surfaces and also possible harmful effects. Dust particles not only cause soiling, but coarse particles can damage surfaces by abrasion. Fine particles of acidic or alkaline charac...

  6. Whither Cometary Dust?

    Science.gov (United States)

    Lisse, Carey M.

    2010-10-01

    In this paper I will discuss recent findings that have important implications for our understanding of the formation and evolution of primitive solar system dust, including: - Nesvorny et al. (2010), following up on their dynamical analyses of the zodiacal dust bands as sourced by the breakup of the Karin (5Mya) and Veritas (8Mya) asteroid families, argue that over 90% of the interplanetary dust cloud at 1 AU comes from JFC comets with near-circularized, low inclination orbits. This implies that the noted IPD collections of anhydrous and hydrous dust particles are likely to be from Oort cloud and JFC comets, respectively, not from asteroids and comets as thought in the past. Hydrous dust particles from comets like 85P/Wild2 and 9P/Tempel 1 would be consistent with results from the STARDUST and Deep Impact experiments. - Estimates of the dust particle size distributions (PSDs) in the comae of 85P/Wild2 (Green et al. 2004, 2007) and 73P/SW-3 (Sitko et al. 2010, Vaubaillon & Reach 2010) and in the trails of comets (Reach et al. 2007) have broken power law structure, with a plateau enhancement of particles of 1 mm - 1 cm in size. This size is also the size of most chondritic inclusions, and the predicted size range of the "aggregational barrier", where collisions between dust particles become destructive. - Studies of the albedo and polarization properties of cometary dust (Kolokolova et al. 2007) suggest there are 2 major groupings, one with low scattering capability and one with high. While these families could possibly have been explained by systematics in the PSDs of the emitted dust, independent work by Lisse et al. (2008) on the mineralogy of a number of highly dusty comets has shown evidence for one family of comets with highly crystalline dust and another with highly amorphous dust.

  7. Fugitive emissions of methane from abandoned, decommissioned oil and gas wells.

    Science.gov (United States)

    Boothroyd, I M; Almond, S; Qassim, S M; Worrall, F; Davies, R J

    2016-03-15

    This study considered the fugitive emissions of methane (CH4) from former oil and gas exploration and production wells drilled to exploit conventional hydrocarbon reservoirs onshore in the UK. This study selected from the 66% of all onshore wells in the UK which appeared to be properly decommissioned (abandoned) that came from 4 different basins and were between 8 and 79 years old. The soil gas above each well was analysed and assessed relative to a nearby control site of similar land use and soil type. The results showed that of the 102 wells considered 30% had soil gas CH4 at the soil surface that was significantly greater than their respective control. Conversely, 39% of well sites had significant lower surface soil gas CH4 concentrations than their respective control. We interpret elevated soil gas CH4 concentrations to be the result of well integrity failure, but do not know the source of the gas nor the route to the surface. Where elevated CH4 was detected it appears to have occurred within a decade of it being drilled. The flux of CH4 from wells was 364 ± 677 kg CO2eq/well/year with a 27% chance that the well would have a negative flux to the atmosphere independent of well age. This flux is low relative to the activity commonly used on decommissioned well sites (e.g. sheep grazing), however, fluxes from wells that have not been appropriately decommissioned would be expected to be higher. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  8. Communication plan for windblown dust.

    Science.gov (United States)

    2015-05-01

    Windblown dust events occur in Arizona, and blowing dust has been considered a contributing factor to serious crashes on the : segment of Interstate 10 (I10) between Phoenix and Tucson, as well as on other Arizona roadways. Arizonas dust events...

  9. Suppression chamber

    International Nuclear Information System (INIS)

    Goto, Hiroshi; Tsuji, Akio.

    1976-01-01

    Purpose: To miniaturize the storage tank of condensated water in BWR reactor. Constitution: A diaphragm is provided in a suppression chamber thereby to partition the same into an inner compartment and an outer compartment. In one of said compartments there is stored clean water to be used for feeding at the time of separating the reactor and for the core spray system, and in another compartment there is stored water necessary for accomplishing the depressurization effect at the time of coolant loss accident. To the compartment in which clean water is stored there is connected a water cleaning device for constantly maintaining water in clean state. As this cleaning device an already used fuel pool cleaning device can be utilized. Further, downcomers for accomplishing the depressurization function are provided in both inner compartment and outer compartment. The capacity of the storage tank can be reduced by the capacity of clean water within the suppression chamber. (Ikeda, J.)

  10. Spatial Variability and Structure of Hydrothermal Ecosystems at the Tempus Fugit Vent on the Galápagos Spreading Center

    Science.gov (United States)

    Raineault, N.; Smart, C.; Marsh, L.; Shank, T.; Fisher, C. R.; Ballard, R. D.

    2016-02-01

    Our early understanding of hydrothermal vent ecology originated from the historic vent sites along the Galápagos Spreading Center (GSC). In 1977, images of these newly discovered chemosynthetic environments changed the way scientists viewed life at depths beyond which sunlight could penetrate. Since the initial discovery, large-scale disturbances as a result of eruptive and tectonic activity have both destroyed and created vent habitats along the GSC. Four years ago, visual observations during the discovery of the active Tempus Fugit vent site at 86°W revealed a large peripheral field of dead vesicomyid clams, indicative of the persistence of hydrothermal activity at this field, likely for more than 20 years. From our knowledge of succession at these vent communities, the occurrence of juvenile clams amongst mature live clams, bathymodiolus mussels and siboglinid tubeworms indicates that there have been multiple colonization events. Riftia tubeworms only observed in nascent stages of growth in 2011 now have have tubes almost 4 m in length in some cases. In 2015 the E/V Nautilus mapped an area of diffuse flow in the Tempus Fugit field (100 m x 150 m) at centimeter level resolution using the standard ROV Hercules imaging suite, comprised of stereo cameras and a structured light laser sensor. This system, along with ROV HD video, samples, and environmental sensors, documented hydrothermal activity and biological community structure (e.g., Riftia tubeworms only observed in nascent stages of growth in 2011 now, in 2015, have tubes almost 4 m in length). Analysis of the resulting high-resolution photo mosaic and samples will address questions regarding distribution of species surrounding hydrothermal activity. This large-scale cohesive imagery provides us with information about the community structure associated with these ecosystems at a moment in time, while the assessment of fluid flow and associated faunal assemblages will provide a proxy for the temporal and

  11. Inventory assessment and determination of properties of dust contamination in the Shelter under-roof space

    International Nuclear Information System (INIS)

    Bogatov, S.A.

    2000-01-01

    Experimental results on study of radionuclide contamination of surfaces under the roof of Shelter have been analyzed. Values of 'loose' and fixed fuel contamination densities and aerodynamic diameters of dust particles capable of resuspension are obtained. Long term efficiency of dust suppression system under the Shelter roof has been estimated. On the base of retrospective analysis of the results, fuel dust inventory on the surfaces under the Shelter roof was evaluated. 14 refs., 5 tab., 3 figs

  12. Determination of releaes from a fugitive or diffuse source using downwind air-monitoring and site-specific meteorological data

    Energy Technology Data Exchange (ETDEWEB)

    Culp, T.; Kovacic, J.; Deola, R. [Sandia National Lab., Albuquerque, NM (United States)

    1996-12-31

    In order to demonstrate compliance with annual radiological dose limits, air-dispersion modeling is often performed. Many air-dispersion models calculate the effects of radionuclide releases. These models do not determine the actual release; they rely on either measured release data from the source or an estimate of the source release based on process knowledge. The EPA provides clear guidance for the determination of annual radionuclide releases from point sources (i.e. facility stacks and vents). However, clear guidance for the determination of radionuclide releases from diffuse or fugitive sources is not available.

  13. Development of a life-cycle fugitive methane emissions model utilizing device level emissions and activity factors

    Science.gov (United States)

    Englander, J.; Brandt, A. R.

    2017-12-01

    There has been numerous studies in quantifying the scale of fugitive emissions from across the natural gas value chain. These studies have typically focused on either specific types of equipment (such as valves) or on a single part of the life-cycle of natural gas production (such as gathering stations).1,2 However it has been demonstrated that average emissions factors are not sufficient for representing leaks in the natural gas system.3 In this work, we develop a robust estimate of fugitive emissions rates by incorporating all publicly available studies done at the component up to the process level. From these known studies, we create a database of leaks with normalized nomenclature from which leak estimates can be drawn from actual leak observations. From this database, and parameterized by meta-data such as location, scale of study, or placement in the life-cycle, we construct stochastic emissions factors specific for each process unit. This will be an integrated tool as part of the Oil production greenhouse gas estimator (OPGEE) as well as the Fugitive Emissions Abatement Simulation Toolkit (FEAST) models to enhances their treatment of venting and fugitive emissions, and will be flexible to include user provided data and input parameters.4,51. Thoma, ED et al. Assessment of Uinta Basin Oil and Natural Gas Well Pad Pneumatic Controller Emissions. J. Environ. Prot. 2017. 2. Marchese, AJ et al. Methane Emissions from United States Natural Gas Gathering and Processing. ES&T 2015. doi:10.1021/acs.est.5b02275 3. Brandt, AR et al. Methane Leaks from Natural Gas Systems Follow Extreme Distributions. ES&T 2016. doi:10.1021/acs.est.6b04303 4. El-Houjeiri, HM et al. An open-source LCA tool estimating greenhouse gas emissions from crude oil production using field characteristics. ES&T 2013. doi: 10.1021/es304570m 5. Kemp, CE et al. Comparing Natural Gas Leakage Detection Technologies Using an Open-Source `Virtual Gas Field' Simulator. ES&T 2016. doi:10.1021/acs.est.5b

  14. Dust in Space

    Indian Academy of Sciences (India)

    "They cannot look out far·IThey cannot look in deep. I. But when was that ever a bar ITo any watch they keep?" - Robert Frost, (Neither Out Far Nor In Deep'. Dust grains in space, which absorb and redden starlight, were once considered to be a nuisance for astronomers, but the study of dust has be- come important in ...

  15. Dust in Space

    Indian Academy of Sciences (India)

    Figure B. The concept of photon nlust travel such that the probability of its interacting is interaction length is ex- almost unity. Putting the above probability equal to unity, and plained. writing ~x = 1, the interaction length, 1, is given by 1 = (/n'. How much Dust is there? One can estimate the amount of dust in interstellar space ...

  16. Dust in planetary nebulae

    International Nuclear Information System (INIS)

    Mathis, J.S.

    1978-01-01

    The author's review concentrates on theoretical aspects of dust in planetary nebulae (PN). He considers the questions: how much dust is there is PN; what is its composition; what effects does it have on the ionization structure, on the dynamics of the nebula. (Auth.)

  17. Respirable dust measured downwind during rock dust application.

    Science.gov (United States)

    Harris, M L; Organiscak, J; Klima, S; Perera, I E

    2017-05-01

    The Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health (NIOSH) conducted underground evaluations in an attempt to quantify respirable rock dust generation when using untreated rock dust and rock dust treated with an anticaking additive. Using personal dust monitors, these evaluations measured respirable rock dust levels arising from a flinger-type application of rock dust on rib and roof surfaces. Rock dust with a majority of the respirable component removed was also applied in NIOSH's Bruceton Experimental Mine using a bantam duster. The respirable dust measurements obtained downwind from both of these tests are presented and discussed. This testing did not measure miners' exposure to respirable coal mine dust under acceptable mining practices, but indicates the need for effective continuous administrative controls to be exercised when rock dusting to minimize the measured amount of rock dust in the sampling device.

  18. Lunar Dust Mitigation Screens

    Science.gov (United States)

    Knutson, Shawn; Holloway, Nancy

    With plans for the United States to return to the moon, and establish a sustainable human presence on the lunar surface many issues must be successfully overcome. Lunar dust is one of a number of issues with the potential to create a myriad of problems if not adequately addressed. Samples of dust brought back from Apollo missions show it to be soft, yet sharp and abrasive. The dust consists of a variety of morphologies including spherical, angular blocks, shards, and a number of irregular shapes. One of the main issues with lunar dust is its attraction to stick to anything it comes in contact with (i.e. astronauts, equipment, habitats, etc.). Ionized radiation from the sun strikes the moon's surface and creates an electrostatic charge on the dust. Further, the dust harbors van der Waals forces making it especially difficult to separate once it sticks to a surface. During the Apollo missions, it was discovered that trying to brush the lunar dust from spacesuits was not effective, and rubbing it caused degradation of the suit material. Further, when entering the lunar module after moonwalks, the astronauts noted that the dust was so prolific inside the cabin that they inhaled and ingested it, causing at least one of them, Harrison "Jack" Schmidt, to report irritation of the throat and lungs. It is speculated that the dust could also harm an astronaut's nervous and cardiovascular systems, especially during an extended stay. In addition to health issues, the dust can also cause problems by scouring reflective coatings off of thermal blankets, and roughening surfaces of windows and optics. Further, panels on solar cells and photovoltaics can also be compromised due to dust sticking on the surfaces. Lunar dust has the capacity to penetrate seals, interfere with connectors, as well as mechanisms on digging machines, all of which can lead to problems and failure. To address lunar dust issues, development of electrostatic screens to mitigate dust on sur-faces is currently

  19. Pathways of high-latitude dust in the North Atlantic

    Science.gov (United States)

    Baddock, Matthew C.; Mockford, Tom; Bullard, Joanna E.; Thorsteinsson, Throstur

    2017-02-01

    The contribution of mineral dust from high-latitude sources has remained an under-examined feature of the global dust cycle. Dust events originating at high latitudes can provide inputs of aeolian sediment to regions lying well outside the subtropical dust belt. Constraining the seasonal variability and preferential pathways of dust from high-latitude sources is important for understanding the potential impacts that the dust may have on wider environmental systems, such as nearby marine or cryospheric domains. This study quantifies dust pathways from two areas exhibiting different emission dynamics in the north and south of Iceland, which is a prominent Northern Hemisphere dust source. The analysis uses air parcel trajectory modelling, and for the first time for high-latitude sources, explicitly links all trajectory simulations to time-specific (meteorological) observations of suspended dust. This approach maximises the potential for trajectories to represent dust, and illustrates that trajectory climatologies not limited to dust can grossly overestimate the potential for dust transport. Preferential pathways emerge that demonstrate the role of Iceland in supplying dust to the Northern Atlantic and sub-Arctic oceans. For dust emitted from northern sources, a dominant route exists to the northeast, into the Norwegian, Greenland and Barents Seas, although there is also potential for delivery to the North Atlantic in summer months. From the southern sources, the primary pathway extends into the North Atlantic, with a high density of trajectories extending as far south as 50°N, particularly in spring and summer. Common to both southern and northern sources is a pathway to the west-southwest of Iceland into the Denmark Strait and towards Greenland. For trajectories simulated at ≤500 m, the vertical development of dust plumes from Iceland is limited, likely due to the stable air masses of the region suppressing the potential for vertical motion. Trajectories rarely

  20. Characterization of airborne float coal dust emitted during continuous mining, longwall mining and belt transport.

    Science.gov (United States)

    Shahan, M R; Seaman, C E; Beck, T W; Colinet, J F; Mischler, S E

    2017-09-01

    Float coal dust is produced by various mining methods, carried by ventilating air and deposited on the floor, roof and ribs of mine airways. If deposited, float dust is re-entrained during a methane explosion. Without sufficient inert rock dust quantities, this float coal dust can propagate an explosion throughout mining entries. Consequently, controlling float coal dust is of critical interest to mining operations. Rock dusting, which is the adding of inert material to airway surfaces, is the main control technique currently used by the coal mining industry to reduce the float coal dust explosion hazard. To assist the industry in reducing this hazard, the Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health initiated a project to investigate methods and technologies to reduce float coal dust in underground coal mines through prevention, capture and suppression prior to deposition. Field characterization studies were performed to determine quantitatively the sources, types and amounts of dust produced during various coal mining processes. The operations chosen for study were a continuous miner section, a longwall section and a coal-handling facility. For each of these operations, the primary dust sources were confirmed to be the continuous mining machine, longwall shearer and conveyor belt transfer points, respectively. Respirable and total airborne float dust samples were collected and analyzed for each operation, and the ratio of total airborne float coal dust to respirable dust was calculated. During the continuous mining process, the ratio of total airborne float coal dust to respirable dust ranged from 10.3 to 13.8. The ratios measured on the longwall face were between 18.5 and 21.5. The total airborne float coal dust to respirable dust ratio observed during belt transport ranged between 7.5 and 21.8.

  1. Quantifying Anthropogenic Dust Emissions

    Science.gov (United States)

    Webb, Nicholas P.; Pierre, Caroline

    2018-02-01

    Anthropogenic land use and land cover change, including local environmental disturbances, moderate rates of wind-driven soil erosion and dust emission. These human-dust cycle interactions impact ecosystems and agricultural production, air quality, human health, biogeochemical cycles, and climate. While the impacts of land use activities and land management on aeolian processes can be profound, the interactions are often complex and assessments of anthropogenic dust loads at all scales remain highly uncertain. Here, we critically review the drivers of anthropogenic dust emission and current evaluation approaches. We then identify and describe opportunities to: (1) develop new conceptual frameworks and interdisciplinary approaches that draw on ecological state-and-transition models to improve the accuracy and relevance of assessments of anthropogenic dust emissions; (2) improve model fidelity and capacity for change detection to quantify anthropogenic impacts on aeolian processes; and (3) enhance field research and monitoring networks to support dust model applications to evaluate the impacts of disturbance processes on local to global-scale wind erosion and dust emissions.

  2. Fugitive emission inventory from Brazilian oil and gas industry (2000-2005) and discussion of mitigation measures

    Energy Technology Data Exchange (ETDEWEB)

    Carloni, Flavia A.; D' Avignon, Alexandre; La Rovere, Emilio L. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Centro Clima

    2008-07-01

    The objective of this work is to evaluate current emissions of GHGs within the Brazilian oil and gas industry, specifically the fugitive emissions arising from exploration and production. Besides, projects for mitigating these emissions and opportunities for the national industry are investigated. Results show that N{sub 2}O contributes little to fugitive emissions from the oil and gas industry, principally from gas sector. NMVOC emissions are significant, principally from the oil sector. In relation to CO{sub 2} and CH{sub 4} emissions, the oil sector emits more CO{sub 2} while the gas sector contributes more to CH{sub 4} emissions. In both sectors flaring is the activity that emits most CO{sub 2}. In relation to CH{sub 4} the principal contribution to emissions are from exploration and production onshore, although offshore activities as a whole play a greater part in the national industry. The results make it clear that the use of gas from flaring activity is a great opportunity for emission mitigation projects. From a business point of view, methane emissions could mean lost opportunities in selling natural gas. The Kyoto Protocol mechanisms, as the Clean Development Mechanism and Joint Implementation actions, provide the opportunity to stimulate investments in projects for reducing flaring and venting of associated gas. (author)

  3. Remote sensing of fugitive methane emissions from oil and gas production in North American tight geologic formations

    Science.gov (United States)

    Schneising, Oliver; Burrows, John P.; Dickerson, Russell R.; Buchwitz, Michael; Reuter, Maximilian; Bovensmann, Heinrich

    2014-10-01

    In the past decade, there has been a massive growth in the horizontal drilling and hydraulic fracturing of shale gas and tight oil reservoirs to exploit formerly inaccessible or unprofitable energy resources in rock formations with low permeability. In North America, these unconventional domestic sources of natural gas and oil provide an opportunity to achieve energy self-sufficiency and to reduce greenhouse gas emissions when displacing coal as a source of energy in power plants. However, fugitive methane emissions in the production process may counter the benefit over coal with respect to climate change and therefore need to be well quantified. Here we demonstrate that positive methane anomalies associated with the oil and gas industries can be detected from space and that corresponding regional emissions can be constrained using satellite observations. On the basis of a mass-balance approach, we estimate that methane emissions for two of the fastest growing production regions in the United States, the Bakken and Eagle Ford formations, have increased by 990 ± 650 ktCH4 yr-1 and 530 ± 330 ktCH4 yr-1 between the periods 2006-2008 and 2009-2011. Relative to the respective increases in oil and gas production, these emission estimates correspond to leakages of 10.1% ± 7.3% and 9.1% ± 6.2% in terms of energy content, calling immediate climate benefit into question and indicating that current inventories likely underestimate the fugitive emissions from Bakken and Eagle Ford.

  4. Chemical characterization of sanding dust and methylene chloride usage in automotive refinishing: implications for occupational and environmental health.

    Science.gov (United States)

    Enander, Richard T; Gute, David M; Cohen, Howard J; Brown, Linfield C; Desmaris, Anne Marie C; Missaghian, Richard

    2002-01-01

    Surface preparation activities conducted during automotive refinishing present several potential human health and environmental risks. This study examines the chemical composition of vehicle sanding dust and the prevalence of methylene chloride use as a basis for evaluating potential chemical exposures in the work environment, fugitive environmental releases, and take-home toxics. This article reports on the findings of (1) a statewide technology and work practices survey of 353 licensed auto body shops and (2) laboratory analyses of sanding dust representing more than 200 vehicles, 10 commercial body filler compounds, and work shirts worn during vehicle sanding while using nonventilated equipment. Survey data revealed that the majority of shops (78%) do not use ventilated sanding equipment, that most workers (55%) take their work clothes and shoes home at the end of the workday, and that 17% of the respondents used a methylene chloride-based paint stripper as an adjunct to mechanical sanding. Laboratory results showed that Pb, As, Cr, Mn, and Ni were present in the sanding dust at every facility tested. Lead concentrations in sanding dust were found to be highest at facilities that performed complete vehicle refinishing (range 770 to 7300 ppm) and at a collision repair shop that used a high-lead content body filler compound (1800 ppm). Hexavalent chromium also was found in two vocational high school paint dust samples at concentrations of 54 and 710 ppm. When total lead and chromium concentrations reached 7300 and 2300 ppm, respectively, facility sanding dust samples failed the U.S. Environmental Protection Agency's Toxicity Characteristic Leaching Procedure for hazardous waste. Metals found in the sanding dust also were present on the work shirts of technicians-ranging from 0.06 (Cd) to 81 (Mg) microg/inch2 of cloth-who sanded on paint without ventilated equipment. Results suggest that sanding dust and methylene chloride paint strippers used in vehicle

  5. Economics of wood dust

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, J.A.

    1980-11-01

    This article reviews the economic effects of wood dust. The most important use of wood today is a fuel, and wood chips and shavings are sources of feedstock for boilers. Other uses include wood chips in the manufacture of particleboard, wood dust as bedding in riding stables and race tracks, as mulch for florists, and as an absorbent in the meat packing industry. The installation of dust collection systems is strongly urged as the consequences of inadequate collection include rapid machine wear, poor environmental conditions for workers, general interference with work, and its combustibility makes it a constant fire hazard.

  6. The aeolian dust accumulation curve

    NARCIS (Netherlands)

    Goossens, D.

    2001-01-01

    This article presents a simple physical concept of aeolian dust accumulation, based on the behaviour of the subprocesses of dust deposition and dust erosion. The concept is tested in an aeolian dust wind tunnel. The agreement between the accumulation curve predicted by the model and the accumulation

  7. A Methodology to Monitor Airborne PM10Dust Particles Using a Small Unmanned Aerial Vehicle.

    Science.gov (United States)

    Alvarado, Miguel; Gonzalez, Felipe; Erskine, Peter; Cliff, David; Heuff, Darlene

    2017-02-14

    Throughout the process of coal extraction from surface mines, gases and particles are emitted in the form of fugitive emissions by activities such as hauling, blasting and transportation. As these emissions are diffuse in nature, estimations based upon emission factors and dispersion/advection equations need to be measured directly from the atmosphere. This paper expands upon previous research undertaken to develop a relative methodology to monitor PM 10 dust particles produced by mining activities making use of small unmanned aerial vehicles (UAVs). A module sensor using a laser particle counter (OPC-N2 from Alphasense, Great Notley, Essex, UK) was tested. An aerodynamic flow experiment was undertaken to determine the position and length of a sampling probe of the sensing module. Flight tests were conducted in order to demonstrate that the sensor provided data which could be used to calculate the emission rate of a source. Emission rates are a critical variable for further predictive dispersion estimates. First, data collected by the airborne module was verified using a 5.0 m tower in which a TSI DRX 8533 (reference dust monitoring device, TSI, Shoreview, MN, USA) and a duplicate of the module sensor were installed. Second, concentration values collected by the monitoring module attached to the UAV (airborne module) obtaining a percentage error of 1.1%. Finally, emission rates from the source were calculated, with airborne data, obtaining errors as low as 1.2%. These errors are low and indicate that the readings collected with the airborne module are comparable to the TSI DRX and could be used to obtain specific emission factors from fugitive emissions for industrial activities.

  8. A Methodology to Monitor Airborne PM10 Dust Particles Using a Small Unmanned Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Miguel Alvarado

    2017-02-01

    Full Text Available Throughout the process of coal extraction from surface mines, gases and particles are emitted in the form of fugitive emissions by activities such as hauling, blasting and transportation. As these emissions are diffuse in nature, estimations based upon emission factors and dispersion/advection equations need to be measured directly from the atmosphere. This paper expands upon previous research undertaken to develop a relative methodology to monitor PM10 dust particles produced by mining activities making use of small unmanned aerial vehicles (UAVs. A module sensor using a laser particle counter (OPC-N2 from Alphasense, Great Notley, Essex, UK was tested. An aerodynamic flow experiment was undertaken to determine the position and length of a sampling probe of the sensing module. Flight tests were conducted in order to demonstrate that the sensor provided data which could be used to calculate the emission rate of a source. Emission rates are a critical variable for further predictive dispersion estimates. First, data collected by the airborne module was verified using a 5.0 m tower in which a TSI DRX 8533 (reference dust monitoring device, TSI, Shoreview, MN, USA and a duplicate of the module sensor were installed. Second, concentration values collected by the monitoring module attached to the UAV (airborne module obtaining a percentage error of 1.1%. Finally, emission rates from the source were calculated, with airborne data, obtaining errors as low as 1.2%. These errors are low and indicate that the readings collected with the airborne module are comparable to the TSI DRX and could be used to obtain specific emission factors from fugitive emissions for industrial activities.

  9. 3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies

    Science.gov (United States)

    Shu, Anthony; Collette, Andrew; Drake, Keith; Grün, Eberhard; Horányi, Mihály; Kempf, Sascha; Mocker, Anna; Munsat, Tobin; Northway, Paige; Srama, Ralf; Sternovsky, Zoltán; Thomas, Evan

    2012-07-01

    A hypervelocity dust accelerator for studying micrometeorite impacts has been constructed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) at the University of Colorado. Based on the Max-Planck-Institüt für Kernphysik (MPI-K) accelerator, this accelerator is capable of emitting single particles of a specific mass and velocity selected by the user. The accelerator consists of a 3 MV Pelletron generator with a dust source, four image charge pickup detectors, and two interchangeable target chambers: a large high-vacuum test bed and an ultra-high vacuum impact study chamber. The large test bed is a 1.2 m diameter, 1.5 m long cylindrical vacuum chamber capable of pressures as low as 10-7 torr while the ultra-high vacuum chamber is a 0.75 m diameter, 1.1 m long chamber capable of pressures as low as 10-10 torr. Using iron dust of up to 2 microns in diameter, final velocities have been measured up to 52 km/s. The spread of the dust particles and the effect of electrostatic focusing have been measured using a long exposure CCD and a quartz target. Furthermore, a new technique of particle selection is being developed using real time digital filtering techniques. Signals are digitized and then cross-correlated with a shaped filter, resulting in a suppressed noise floor. Improvements over the MPI-K design, which include a higher operating voltage and digital filtering for detection, increase the available parameter space of dust emitted by the accelerator. The CCLDAS dust facility is a user facility open to the scientific community to assist with instrument calibrations and experiments.

  10. 3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Anthony; Horanyi, Mihaly; Kempf, Sascha; Thomas, Evan [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States); Laboratory for Atmospheric and Space Physics, 1234 Innovation Drive, Boulder, Colorado 80303 (United States); Collette, Andrew; Drake, Keith; Northway, Paige [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); Laboratory for Atmospheric and Space Physics, 1234 Innovation Drive, Boulder, Colorado 80303 (United States); Gruen, Eberhard [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); MPI fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Mocker, Anna [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); MPI fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); IRS, Universitaet Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart (Germany); Munsat, Tobin [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States); Srama, Ralf [MPI fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); IRS, Universitaet Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart (Germany); and others

    2012-07-15

    A hypervelocity dust accelerator for studying micrometeorite impacts has been constructed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) at the University of Colorado. Based on the Max-Planck-Instituet fuer Kernphysik (MPI-K) accelerator, this accelerator is capable of emitting single particles of a specific mass and velocity selected by the user. The accelerator consists of a 3 MV Pelletron generator with a dust source, four image charge pickup detectors, and two interchangeable target chambers: a large high-vacuum test bed and an ultra-high vacuum impact study chamber. The large test bed is a 1.2 m diameter, 1.5 m long cylindrical vacuum chamber capable of pressures as low as 10{sup -7} torr while the ultra-high vacuum chamber is a 0.75 m diameter, 1.1 m long chamber capable of pressures as low as 10{sup -10} torr. Using iron dust of up to 2 microns in diameter, final velocities have been measured up to 52 km/s. The spread of the dust particles and the effect of electrostatic focusing have been measured using a long exposure CCD and a quartz target. Furthermore, a new technique of particle selection is being developed using real time digital filtering techniques. Signals are digitized and then cross-correlated with a shaped filter, resulting in a suppressed noise floor. Improvements over the MPI-K design, which include a higher operating voltage and digital filtering for detection, increase the available parameter space of dust emitted by the accelerator. The CCLDAS dust facility is a user facility open to the scientific community to assist with instrument calibrations and experiments.

  11. 3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies.

    Science.gov (United States)

    Shu, Anthony; Collette, Andrew; Drake, Keith; Grün, Eberhard; Horányi, Mihály; Kempf, Sascha; Mocker, Anna; Munsat, Tobin; Northway, Paige; Srama, Ralf; Sternovsky, Zoltán; Thomas, Evan

    2012-07-01

    A hypervelocity dust accelerator for studying micrometeorite impacts has been constructed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) at the University of Colorado. Based on the Max-Planck-Institüt für Kernphysik (MPI-K) accelerator, this accelerator is capable of emitting single particles of a specific mass and velocity selected by the user. The accelerator consists of a 3 MV Pelletron generator with a dust source, four image charge pickup detectors, and two interchangeable target chambers: a large high-vacuum test bed and an ultra-high vacuum impact study chamber. The large test bed is a 1.2 m diameter, 1.5 m long cylindrical vacuum chamber capable of pressures as low as 10(-7) torr while the ultra-high vacuum chamber is a 0.75 m diameter, 1.1 m long chamber capable of pressures as low as 10(-10) torr. Using iron dust of up to 2 microns in diameter, final velocities have been measured up to 52 km/s. The spread of the dust particles and the effect of electrostatic focusing have been measured using a long exposure CCD and a quartz target. Furthermore, a new technique of particle selection is being developed using real time digital filtering techniques. Signals are digitized and then cross-correlated with a shaped filter, resulting in a suppressed noise floor. Improvements over the MPI-K design, which include a higher operating voltage and digital filtering for detection, increase the available parameter space of dust emitted by the accelerator. The CCLDAS dust facility is a user facility open to the scientific community to assist with instrument calibrations and experiments.

  12. Impact of mineral dust on nitrate, sulfate, and ozone in transpacific Asian pollution plumes

    Directory of Open Access Journals (Sweden)

    T. D. Fairlie

    2010-04-01

    Full Text Available We use a 3-D global chemical transport model (GEOS-Chem to interpret aircraft observations of nitrate and sulfate partitioning in transpacific dust plumes during the INTEX-B campaign of April–May 2006. The model includes explicit transport of size-resolved mineral dust and its alkalinity, nitrate, and sulfate content. The observations show that particulate nitrate is primarily associated with dust, sulfate is primarily associated with ammonium, and Asian dust remains alkaline across the Pacific. This can be reproduced in the model by using a reactive uptake coefficient for HNO3 on dust (γ(HNO3 ~10−3 much lower than commonly assumed in models and possibly reflecting limitation of uptake by dust dissolution. The model overestimates gas-phase HNO3 by a factor of 2–3, typical of previous model studies; we show that this cannot be corrected by uptake on dust. We find that the fraction of aerosol nitrate on dust in the model increases from ~30% in fresh Asian outflow to 80–90% over the Northeast Pacific, reflecting in part the volatilization of ammonium nitrate and the resulting transfer of nitrate to the dust. Consumption of dust alkalinity by uptake of acid gases in the model is slow relative to the lifetime of dust against deposition, so that dust does not acidify (at least not in the bulk. This limits the potential for dust iron released by acidification to become bio-available upon dust deposition. Observations in INTEX-B show no detectable ozone depletion in Asian dust plumes, consistent with the model. Uptake of HNO3 by dust, suppressing its recycling to NOx, reduces Asian pollution influence on US surface ozone in the model by 10–15% or up to 1 ppb.

  13. Dust filter testing

    International Nuclear Information System (INIS)

    Dupoux, J.

    1975-01-01

    The composition of dust filters used in cleanup systems for radioactive gaseous effluents is described as well as the technical controls, especially efficiency measured by a soda fluorescein aerosol [fr

  14. Dust mite (image)

    Science.gov (United States)

    This is a magnified photograph of a dust mite. Mites are carriers (vectors) of many important diseases including typhus (scrub and murine) and rickettsialpox. (Image courtesy of the Centers for Disease Control ...

  15. Cosmic Dust Catalog

    Data.gov (United States)

    National Aeronautics and Space Administration — Since May 1981, the National Aeronautics and Space Administration (NASA) has used aircraft to collect cosmic dust (CD) particles from Earth's stratosphere. Specially...

  16. Nano Dust Analyzer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a new highly sensitive instrument to confirm the existence of the so-called nano-dust particles, characterize their impact parameters, and...

  17. Multiregional environmental comparison of fossil fuel power generation-Assessment of the contribution of fugitive emissions from conventional and unconventional fossil resources

    NARCIS (Netherlands)

    Bouman, Evert A.; Ramirez, Andrea; Hertwich, Edgar G.

    2015-01-01

    In this paper we investigate the influence of fugitive methane emissions from coal, natural gas, and shale gas extraction on the greenhouse gas (GHG) impacts of fossil fuel power generation through its life cycle. A multiregional hybridized life cycle assessment (LCA) model is used to evaluate

  18. 40 CFR 63.7293 - What work practice standards must I meet for fugitive pushing emissions if I have a non-recovery...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 13 2010-07-01 2010-07-01 false What work practice standards must I meet for fugitive pushing emissions if I have a non-recovery coke oven battery? 63.7293 Section 63.7293 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR...

  19. 40 CFR 63.7292 - What work practice standards must I meet for fugitive pushing emissions if I have a by-product...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 13 2010-07-01 2010-07-01 false What work practice standards must I meet for fugitive pushing emissions if I have a by-product coke oven battery with horizontal flues? 63.7292 Section 63.7292 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR...

  20. Effect of dust size distribution and dust charge fluctuation on dust ion ...

    Indian Academy of Sciences (India)

    2016-06-17

    Jun 17, 2016 ... Dusty plasma; dust-acoustic shock wave; dust size distribution; adiabatic dust charge variation; negative ions. PACS Nos 52.27.Lw; 52.35.Tc; 52.35.Mw. 1. Introduction. The low-frequency dust ion-acoustic waves are typi- cal acoustic modes in unmagnetized and collisionless dusty plasma with a weak ...

  1. Effect of dust size distribution and dust charge fluctuation on dust ion ...

    Indian Academy of Sciences (India)

    The effects of dust size distribution and dust charge fluctuation of dust grains on the small but finite amplitude nonlinear dust ion-acoustic shock waves, in an unmagnetized multi-ion dusty plasma which contains negative ions, positive ions and electrons, are studied in this paper. A Burgers equation and its stationary ...

  2. Quantifying dust plume formation and aerosol size distribution during the Saharan Mineral Dust Experiment in North Africa

    KAUST Repository

    Khan, Basit Ali

    2015-01-01

    Dust particles mixed in the free troposphere have longer lifetimes than airborne particles near the surface. Their cumulative radiative impact on earth’s meteorological processes and climate might be significant despite their relatively small contribution to total dust abundance. One example is the elevated dust--laden Saharan Air Layer (SAL) over the equatorial North Atlantic, which cools the sea surface and likely suppresses hurricane activity. To understand the formation mechanisms of SAL, we combine model simulations and dust observations collected during the first stage of the Saharan Mineral Dust Experiment (SAMUM--I), which sampled dust events that extended from Morocco to Portugal, and investigated the spatial distribution and the microphysical, optical, chemical, and radiative properties of Saharan mineral dust. We employed the Weather Research Forecast model coupled with the Chemistry/Aerosol module (WRF--Chem) to reproduce the meteorological environment and spatial and size distributions of dust. The experimental domain covers northwest Africa including the southern Sahara, Morocco and part of the Atlantic Ocean with 5 km horizontal grid spacing and 51 vertical layers. The experiments were run from 20 May to 9 June 2006, covering the period of most intensive dust outbreaks. Comparisons of model results with available airborne and ground--based observations show that WRF--Chem reproduces observed meteorological fields as well as aerosol distribution across the entire region and along the airplane’s tracks. We evaluated several aerosol uplift processes and found that orographic lifting, aerosol transport through the land/sea interface with steep gradients of meteorological characteristics, and interaction of sea breezes with the continental outflow are key mechanisms that form a surface--detached aerosol plume over the ocean. Comparisons of simulated dust size distributions with airplane and ground--based observations are generally good, but suggest

  3. Effects of Adding Corn Dried Distiller Grains with Solubles (DDGS) to the Dairy Cow Diet and Effects of Bedding in Dairy Cow Slurry on Fugitive Methane Emissions

    Science.gov (United States)

    Massé, Daniel I.; Jarret, Guillaume; Benchaar, Chaouki; Hassanat, Fadi

    2014-01-01

    Simple Summary The objectives of this experiment were to investigate the effects of adding corn DDGS to the dairy cow diet as well as the bedding types (wood shavings, straw or peat moss) on manure fugitive CH4 emissions. The incorporation of DDGS in the diet has increased manure methane emission by 15% and the use of peat moss as bedding has increased manure methane emission by 27%. Abstract The specific objectives of this experiment were to investigate the effects of adding 10% or 30% corn dried distillers grains with solubles (DDGS) to the dairy cow diet and the effects of bedding type (wood shavings, straw or peat moss) in dairy slurry on fugitive CH4 emissions. The addition of DDGS10 to the dairy cow diet significantly increased (29%) the daily amount of fat excreted in slurry compared to the control diet. The inclusion of DDGS30 in the diet increased the daily amounts of excreted DM, volatile solids (VS), fat, neutral detergent fiber (NDF), acid detergent fiber (ADF) and hemicellulose by 18%, 18%, 70%, 30%, 15% and 53%, respectively, compared to the control diet. During the storage experiment, daily fugitive CH4 emissions showed a significant increase of 15% (p < 0.05) for the slurry resulting from the corn DDGS30 diet. The addition of wood shavings and straw did not have a significant effect on daily fugitive CH4 emissions relative to the control diet, whereas the addition of peat moss caused a significant increase of 27% (p < 0.05) in fugitive CH4 emissions. PMID:26479012

  4. Fractal dust grains in plasma

    International Nuclear Information System (INIS)

    Huang, F.; Peng, R. D.; Liu, Y. H.; Chen, Z. Y.; Ye, M. F.; Wang, L.

    2012-01-01

    Fractal dust grains of different shapes are observed in a radially confined magnetized radio frequency plasma. The fractal dimensions of the dust structures in two-dimensional (2D) horizontal dust layers are calculated, and their evolution in the dust growth process is investigated. It is found that as the dust grains grow the fractal dimension of the dust structure decreases. In addition, the fractal dimension of the center region is larger than that of the entire region in the 2D dust layer. In the initial growth stage, the small dust particulates at a high number density in a 2D layer tend to fill space as a normal surface with fractal dimension D = 2. The mechanism of the formation of fractal dust grains is discussed.

  5. Sahara Dust Cloud

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Dust Particles Click on the image for Quicktime movie from 7/15-7/24 A continent-sized cloud of hot air and dust originating from the Sahara Desert crossed the Atlantic Ocean and headed towards Florida and the Caribbean. A Saharan Air Layer, or SAL, forms when dry air and dust rise from Africa's west coast and ride the trade winds above the Atlantic Ocean. These dust clouds are not uncommon, especially during the months of July and August. They start when weather patterns called tropical waves pick up dust from the desert in North Africa, carry it a couple of miles into the atmosphere and drift westward. In a sequence of images created by data acquired by the Earth-orbiting Atmospheric Infrared Sounder ranging from July 15 through July 24, we see the distribution of the cloud in the atmosphere as it swirls off of Africa and heads across the ocean to the west. Using the unique silicate spectral signatures of dust in the thermal infrared, AIRS can detect the presence of dust in the atmosphere day or night. This detection works best if there are no clouds present on top of the dust; when clouds are present, they can interfere with the signal, making it much harder to detect dust as in the case of July 24, 2005. In the Quicktime movie, the scale at the bottom of the images shows +1 for dust definitely detected, and ranges down to -1 for no dust detected. The plots are averaged over a number of AIRS observations falling within grid boxes, and so it is possible to obtain fractional numbers. [figure removed for brevity, see original site] Total Water Vapor in the Atmosphere Around the Dust Cloud Click on the image for Quicktime movie The dust cloud is contained within a dry adiabatic layer which originates over the Sahara Desert. This Saharan Air Layer (SAL) advances Westward over the Atlantic Ocean, overriding the cool, moist air nearer the surface. This burst of very dry air is visible in the AIRS retrieved total water

  6. Tracing Sources and Contamination Assessments of Heavy Metals in Road and Foliar Dusts in a Typical Mining City, China.

    Science.gov (United States)

    Yang, Jie; Teng, Yanguo; Song, Liuting; Zuo, Rui

    2016-01-01

    Road and foliar dust samples from four land-use districts of Panzhihua City, a famous V-Ti magnetite production area of China, were collected to investigate the sources and distribution characteristics of 9 heavy metals (V, Pb, Cd, Cu, Zn, Ni, Cr, Fe, and Mn). The results suggest that foliar samples had smaller particle size and higher heavy metal contents than road dusts. The contamination assessments of heavy metals were as follows: Pb and V (significant enrichment) > Zn, Ni, Cr, Fe, and Mn (moderate enrichment) > Cd and Ni (minimal enrichment). Statistical analyses showed Pb, as the primary pollution element, originated from waste incineration and lead-fuel combustion. The sources of Zn, Ni, Cr, Fe, V, and Mn were fugitive dust and traffic activities. Potential origins of Cu were corrosion of alloys used in vehicle components, vehicle covers, or other metallic surfaces and materials. The sources of Cd were different from any other heavy metals. Traffic and industrial activities were the main anthropogenic origins of heavy metals in dusts of Panzhihua, and more attention should be paid to heavy metal pollution in agricultural area.

  7. Analytical Study of Nonlinear Dust Acoustic Waves in Two-Dimensional Dust Plasma with Dust Charge Variation

    International Nuclear Information System (INIS)

    Lin Chang; Zhang Xiulian

    2005-01-01

    The nonlinear dust acoustic waves in two-dimensional dust plasma with dust charge variation is analytically investigated by using the formally variable separation approach. New analytical solutions for the governing equation of this system have been obtained for dust acoustic waves in a dust plasma for the first time. We derive exact analytical expressions for the general case of the nonlinear dust acoustic waves in two-dimensional dust plasma with dust charge variation.

  8. Dust in planetary nebulae

    International Nuclear Information System (INIS)

    Kwok, S.

    1980-01-01

    A two-component dust model is suggested to explain the infrared emission from planetary nebulae. A cold dust component located in the extensive remnant of the red-giant envelope exterior to the visible nebula is responsible for the far-infrared emission. A ward dust component, which is condensed after the formation of the planetary nebula and confined within the ionized gas shell, emits most of the near- and mid-infrared radiation. The observations of NGC 7027 are shown to be consisten with such a model. The correlation of silicate emission in several planetary nebulae with an approximately +1 spectral index at low radio frequencies suggests that both the silicate and radio emissions originate from the remnant of the circumstellar envelope of th precursor star and are observable only while the planetary nebula is young. It is argued that oxygen-rich stars as well as carbon-rich stars can be progenitors of planetary nebulae

  9. Dust-Plasma Interactions

    International Nuclear Information System (INIS)

    Rosenberg, M.

    2010-01-01

    The objective of our theoretical research under this grant over the past 3 years was to develop new understanding in a range of topics in the physics of dust-plasma interactions, with application to space and the laboratory. We conducted studies related to the physical properties of dust, waves and instabilities in both weakly coupled and strongly coupled dusty plasmas, and innovative possible applications. A major consideration in our choice of topics was to compare theory with experiments or observations, and to motivate new experiments, which we believe is important for developing this relatively new field. Our research is summarized, with reference to our list of journal publications.

  10. Paleo-dust insights onto dust-climate interactions

    Science.gov (United States)

    Albani, S.; Mahowald, N. M.

    2017-12-01

    Mineral dust emissions are affected by changing climate conditions, and in turn dust impacts the atmospheric radiation budget, clouds and biogeochemical cycles. Climate and public health dust-related issues call for attention on the fate of the dust cycle in the future, and the representation of the dust cycle is now part of the strategy of the Paleoclimate Modelling Intercomparison Project phase 4 and the Coupled Model Intercomparison Project phase 6 (PMIP4-CMIP6). Since mineral aerosols are one of the most important natural aerosols, understanding past dust responses to climate in the paleoclimate will allow us to better understand mineral aerosol feedbacks with climate and biogeochemistry in the Anthropocene. Modern observations and paleoclimate records offer the possibility of multiple, complementary views on the global dust cycle, and allow to validate and/or constrain the numerical representation of dust in climate and Earth system models. We present our results from a set of simulations with the Community Earth System Model for different climate states, including present and past climates such as the pre-industrial, the mid-Holocene and the Last Glacial Maximum. A set of simulations including a prognostic dust cycle was thoroughly compared with a wide set of present day observations from different platforms and regions, in order to realistically constrain the magnitude of dust load, surface concentration, deposition, optical properties, and particle size distributions. The magnitude of emissions for past climate regimes was constrained based on compilations of paleodust mass accumulation rates and size distributions, as well as based on information on dust provenance. The comparison with a parallel set of simulations without dust allows estimating the impacts of dust on surface climate. We analyze impacts of dust on the mean and variability of surface temperature and precipitation in each climate state, as well as the impacts that changing dust emissions had

  11. The impact of Saharan Dust on the genesis and evolution of Hurricane Earl (2010)

    Science.gov (United States)

    Pan, B.; Wang, Y.; Hsieh, J. S.; Lin, Y.; Hu, J.; Zhang, R.

    2017-12-01

    Dust, one of the most abundant natural aerosols, can exert substantial radiative and microphysical effects on the regional climate and has potential impacts on the genesis and intensification of tropical cyclones (TCs). A Weather Research and Forecasting Model and the Regional Oceanic Modeling System coupled model (WRF-ROMS) is used to simulate the evolution of Hurricane Earl (2010), of which Earl was interfered by Saharan dust at the TC genesis stage. A new dust module has been implemented to the TAMU two-moment microphysics scheme in the WRF model. It accounts for both dust as Cloud Condensation Nuclei (CCN) and Ice Nuclei (IN). The hurricane track, intensity and precipitation have been compared to the best track data and TRMM precipitation, respectively. The influences of Saharan dust on Hurricane Earl are investigated with dust-CCN, dust-IN, and dust-free scenarios. The analysis shows that Saharan dust changes the latent heat and moisture distribution, invigorates the convections in the hurricane's eyewall, and suppresses the development of Earl. This finding addresses the importance of accounting dust microphysics effect on hurricane predictions.

  12. 75 FR 32142 - Combustible Dust

    Science.gov (United States)

    2010-06-07

    ... Combustible Dust AGENCY: Occupational Safety and Health Administration (OSHA), Labor. ACTION: Notice of combustible dust Web Chat. SUMMARY: OSHA invites interested parties to participate in a Web Chat on the workplace hazards of combustible dust. OSHA plans to use the information gathered in response to this Web...

  13. The dust that lights up the Zodiac

    International Nuclear Information System (INIS)

    Dixon, D.; McDonnell, T.; Carey, B.

    1985-01-01

    The article concerns cosmic dust particles, which vary in size from fine dust to large dust particles which burn-up in the atmosphere as meteors. The composition and properties of cosmic dust; zodiacal light; brownlee particles; capture cell for collecting dust samples in space and hypervelocity impacts of cosmic dust on the cell; are all discussed. (U.K.)

  14. Identification of the exploatation dust in road dust

    Directory of Open Access Journals (Sweden)

    B. Gajdzik

    2012-01-01

    Full Text Available The aim of this publication is to determine models of explore dust from vehicle brake systems and the presentationof measurement results of the exploitation dust, which is separate from road dust. The following methods and measuring devices were used: T-01M device, screen analysis, analysis of chemical composition with the use of a scanning microscope with Energy Dispersive x-ray Spectroscopy (EDS analyser. The measurements for identifying this type of dust were conducted on marked sections of roads: motorway, city road and mountain road. The explored dust was distinguished in the following car systems: brakes, clutch plates, tyres and catalytic converters.

  15. Metal dusting of low alloy steels

    Energy Technology Data Exchange (ETDEWEB)

    Grabke, H.J. (Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)); Bracho-Troconis, C.B. (Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)); Mueller-Lorenz, E.M. (Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany))

    1994-04-01

    The metal dusting of two low alloy steels was investigated at 475 C in flowing CO-H[sub 2]-H[sub 2]O mixtures at atmospheric pressure with a[sub C] > 1. The reaction sequence comprises: (1) oversaturation with C, formation of cementite and its decomposition to metal particles and carbon, and (2) additional carbon deposition on the metal particles from the atmosphere. The metal wastage rate r[sub 1] was determined by analysis of the corrosion product after exposures, this rate is constant with time and virtually independent of the environment. The carbon deposition from the atmosphere was determined by thermogravimetry, its rate r[sub 2] increases linearly with time, which can be explained by the catalytic action of the metal particles - periodic changes are superposed. The rate of carbon deposition r[sub 2] is proportional to the carbon activity in the atmosphere. The metal dusting could not be suppressed by increasing the oxygen activity or preoxidation, even if magnetite should be stable. Addition of H[sub 2]S, however, effectively suppresses the attack. (orig.)

  16. Dust pollution from agriculture

    Science.gov (United States)

    Fine dust particles emitted from agricultural facilities, lands and operations are considered pollutants when they affect public health and welfare. These particles, with a diameter of less than or equal to 2.5 µm (PM2.5) and less than or equal to 10 µm (PM10), are regulated by government agencies. ...

  17. Allergies, asthma, and dust

    Science.gov (United States)

    ... and box springs. House dust may also contain tiny particles of pollen, mold, fibers from clothing and fabrics, and detergents. All of these can also trigger allergies and asthma. Choose the Right Home Furnishings You can do many things to limit ...

  18. Characterization of ice nucleation on different natural dust samples

    Science.gov (United States)

    Kaufmann, Lukas; Hofer, Julian; Marcolli, Claudia; Pinti, Valeria; Hoyle, Christopher; Peter, Thomas

    2014-05-01

    The impact of aerosols on Earth's climate is still uncertain. Therefore a better understanding of direct and indirect effects of aerosols is essential to improve models and the ability to predict future climate change. A natural source of aerosols is desert dust. Laboratory measurements investigating the influence of dust on heterogeneous freezing of water droplets are presented. We performed measurements with seven dust samples collected in the Etosha pan in Namibia, in the Makgadikgadi pan in Botswana (from three different locations), on the Altiplano in Bolivia, in Qatar and in the Hoggar mountains in Algeria. After sieving, the particle diameters of these dusts were < 32 μm. The mineralogical composition of the dusts was determined by X-ray diffraction. For the investigation of the ice nucleation ability of these dusts, emulsion as well as bulk freezing measurements were performed with a differential scanning calorimeter (DSC). For the emulsion measurements a suspension of a dust was mixed with water. Mixed with a mineral oil/lanolin mixture, the water droplets in the emulsion had mean diameters of around 2 μm. Heterogeneous freezing of dusts was characterized by three temperatures for frozen fractions of 0.1, 0.25, and 0.5, respectively. Heterogeneous freezing temperatures for all 7 samples were quite similar, namely 245 - 246.5 K (for frozen fractions of 0.1), 243 - 244.5 K (for 0.25) and 240 - 241.5 K (for 0.5). Emulsions consisting of pure water suspensions froze with onset temperatures of around 237 K. Emulsion measurements with Hoggar mountain dust were also performed with an additional solute such as ammonium sulfate, malonic acid, glucose or PEG 300. Immersion freezing was found to be suppressed in the presence of solutes. For the bulk measurements dusts were suspended in pure water and droplets with radii of about 1 mm were subjected to repeated freezing cycles. Freezing temperatures in the range of 253 - 265 K were found for cooling rates of 10 K

  19. Mechanisms of metal dusting corrosion

    DEFF Research Database (Denmark)

    Hummelshøj, Thomas Strabo

    In this thesis the early stages of metal dusting corrosion is addressed; the development of carbon expanded austenite, C, and the decomposition hereof into carbides. Later stages of metal dusting corrosion are explored by a systematic study of stainless steel foils exposed to metal dusting...... the supersaturated alloy, into a diverse carbide network. Finally, the foils turn into metal dust accompanied by a thinning and disappearance of the foils. Investigations of TEM samples, prepared by means of FIB, on the carbide network revealed a lamellar structure with carbides and austenite. Finally, the mutual...... influence of oxygen and carbon on the metal dusting corrosion is explored. The results indicate that exposure to metal dusting conditions have a detrimental effect on the resistance against oxidation and, conversely, that exposure to oxidation has a detrimental effect on the resistance towards metal dusting...

  20. Lithium Wall Conditioning And Surface Dust Detection On NSTX

    International Nuclear Information System (INIS)

    Skinner, C.H.; Allain, J.P.; Bell, M.G.; Friesen, F.Q.L.; Heim, B.; Jaworski, M.A.; Kugel, H.; Maingi, R.; Rais, B.; Taylor, C.N.

    2011-01-01

    Lithium evaporation onto NSTX plasma facing components (PFC) has resulted in improved energy confinement, and reductions in the number and amplitude of edge-localized modes (ELMs) up to the point of complete ELM suppression. The associated PFC surface chemistry has been investigated with a novel plasma material interface probe connected to an in-vacuo surface analysis station. Analysis has demonstrated that binding of D atoms to the polycrystalline graphite material of the PFCs is fundamentally changed by lithium - in particular deuterium atoms become weakly bonded near lithium atoms themselves bound to either oxygen or the carbon from the underlying material. Surface dust inside NSTX has been detected in real-time using a highly sensitive electrostatic dust detector. In a separate experiment, electrostatic removal of dust via three concentric spiral-shaped electrodes covered by a dielectric and driven by a high voltage 3-phase waveform was evaluated for potential application to fusion reactors

  1. Dust Growth in Astrophysical Plasmas

    Science.gov (United States)

    Bingham, R.; Tsytovich, V. N.

    2002-12-01

    Dust formation in space is important in diverse environments such as dust molecular clouds, proto-planetary nebulae, stellar outbursts, and supernova explosions. The formation of dust proceeds the formation of stellar objects and planets. In all these environments the dust particles interact with both neutral and plasma particles as well as with (ultraviolet) radiation and cosmic rays. The conventional view of grain growth is one based on accretion by the Van der Waals and chemical forces [Watson and Salpeter [14] considered in detail both theoretically and numerically (Kempf at all [6],Meaking [7]( and confirmed recently by micro-gravity experiments Blum et all [2]). The usual point of view is that the dust grow is occurring in dust molecular clouds at very low temperatures ~ (10 - 30)° K and is a slow process - dust grows to a size of about 0.1 μm in 106 - 109 years. This contradicts recent observations of dust growing in winds of C-stars in about 10 years and behind the supernova SN1987A shock in about 500 days. Also recent observation of star formation at the edge of irradiated dust clouds suggests that new plasma mechanism operates in star formation. Dusty plasma mechanisms of agglomeration are analyzed as an explanation of the new astrophysical observation. New micro-gravity experiments are proposed for observing the plasma mechanisms of dust agglomeration at gas pressures substantially higher than used in ([2]. Calculations for the growth rates of dust agglomeration due to plasma mechanisms are presented. It is shown that at large neutral gas densities the dust plasma attraction provides an explanation of dust grow in about 10 days observed in H-star winds. Ionization by cosmic rays and by radioactive dust can provide the dust attraction necessary for forming dust clumping observed in molecular clouds and the fractal plasma clumping can enhance the time to reach the gravitational contraction phase operating at the final stage of star formation. A new

  2. Distribution of dust during two dust storms in Iceland

    Science.gov (United States)

    Ösp Magnúsdóttir, Agnes; Dagsson-Waldhauserova, Pavla; Arnalds, Ólafur; Ólafsson, Haraldur

    2017-04-01

    Particulate matter mass concentrations and size fractions of PM1, PM2.5, PM4, PM10, and PM15 measured in transversal horizontal profile of two dust storms in southwestern Iceland are presented. Images from a camera network were used to estimate the visibility and spatial extent of measured dust events. Numerical simulations were used to calculate the total dust flux from the sources as 180,000 and 280,000 tons for each storm. The mean PM15 concentrations inside of the dust plumes varied from 10 to 1600 ?g?m?3 (PM10 = 7 to 583 ?g?m?3). The mean PM1 concentrations were 97-241 ?g?m?3 with a maximum of 261 ?g?m?3 for the first storm. The PM1/PM2.5 ratios of >0.9 and PM1/PM10 ratios of 0.34-0.63 show that suspension of volcanic materials in Iceland causes air pollution with extremely high PM1 concentrations, similar to polluted urban areas in Europe or Asia. Icelandic volcanic dust consists of a higher proportion of submicron particles compared to crustal dust. Both dust storms occurred in relatively densely inhabited areas of Iceland. First results on size partitioning of Icelandic dust presented here should challenge health authorities to enhance research in relation to dust and shows the need for public dust warning systems.

  3. Composition of interstellar dust

    International Nuclear Information System (INIS)

    Field, G.B.

    1975-01-01

    Direct evidence that interstellar dust is composed partly of silicates, graphite, and water ice is reviewed. Indirect evidence, from recent studies of the chemical composition of interstellar gas, is assessed in terms of two possible models for the formation of the dust: condensation under thermal-equilibrium conditions and accretion under nonequilibrium conditions. It is concluded that probably the more refractory elements condense under equilibrium conditions and that probably the more volatile ones condense under nonequilibrium conditions. Equilibrium condensation may occur either in stellar atmospheres or in circumstellar nebulae, but arguments from stellar evolution favor the latter. If this is correct, all but a tiny fraction of the present interstellar medium has at least once been involved in circumstellar nebulae. This is consistent with the hypothesis that planetary systems are commonplace

  4. PW Vulpeculae - a dust-poor DG Herculis?

    International Nuclear Information System (INIS)

    Gehrz, R.D.; Harrison, T.E.; Ney, E.P.; Matthews, K.; Neugebauer, G.

    1988-01-01

    The paper reports 2.3-19.5 micron infrared photometry of the very slow nova PW Vul during August 12, 1984 to October 19, 1986. Some aspects of the eruptions of PW Vul and DQ Her were similar in detail, but differing physical conditions in the ejecta caused dust formation to proceed at vastly different efficiencies in the two novae. It is argued that, although an optically thin dust shell eventually condensed in the ejecta of PW Vul, the dust formation process was severely suppressed compared to classical DQ Her novae. Expansion of the pseudophotosphere implies a very slow ejection speed which is consistent with the long dust formation time. Several effects which could have suppressed the grain growth process are discussed. The nova remnant emitted between 500 and 40,000 solar luminosities 812 days after the eruption. Comparison of the photometric data for PW Vul with recent measurements of its sister nova, QU Vul, implies that the presence of silicate emission and strong fine structure line emission during the late stages of PW Vul's development cannot be completely ruled out. 43 references

  5. Dust acoustic shock wave at high dust density

    International Nuclear Information System (INIS)

    Ghosh, Samiran; Sarkar, Susmita; Khan, Manoranjan; Avinash, K.; Gupta, M. R.

    2003-01-01

    Dust acoustic (DA) shock wave at high dust density, i.e., the dust electroacoustic (DEA) or dust Coulomb (DC) shock wave has been investigated incorporating the nonadiabatic dust charge variation. The nonlinear DEA (DC) shock wave is seen to be governed by the Korteweg-de Vries Burger equation, in which the Burger term is proportional to the nonadiabaticity generated dissipation. It is seen that the shock strength decreases but after reaching minimum, it increases as the dust space charge density |q d n d | increases and the shock strength of DA wave is greater than that of DEA (DC) wave. Moreover the DEA (DC) shock width increases appreciably with increase mass m i of the ion component of the dusty plasma but for DA shock wave the effect is weak

  6. Dust, Climate, and Human Health

    Science.gov (United States)

    Maynard, Nancy G.

    2003-01-01

    Air pollution from both natural and anthropogenic causes is considered to be one of the most serious world-wide environment-related health problems, and is expected to become worse with changes in the global climate. Dust storms from the atmospheric transport of desert soil dust that has been lifted and carried by the winds - often over significant distances - have become an increasingly important emerging air quality issue for many populations. Recent studies have shown that the dust storms can cause significant health impacts from the dust itself as well as the accompanying pollutants, pesticides, metals, salt, plant debris, and other inorganic and organic materials, including viable microorganisms (bacteria, viruses and fungi). For example, thousands of tons of Asian desert sediments, some containing pesticides and herbicides from farming regions, are commonly transported into the Arctic during dust storm events. These chemicals have been identified in animal and human tissues among Arctic indigenous populations. Millions of tons of airborne desert dust are being tracked by satellite imagery, which clearly shows the magnitude as well as the temporal and spatial variability of dust storms across the "dust belt" regions of North Africa, the Middle East, and China. This paper summarizes the most recent findings on the effects of airborne desert dust on human health as well as potential climate influences on dust and health.

  7. Parameterizing the interstellar dust temperature

    Science.gov (United States)

    Hocuk, S.; Szűcs, L.; Caselli, P.; Cazaux, S.; Spaans, M.; Esplugues, G. B.

    2017-08-01

    The temperature of interstellar dust particles is of great importance to astronomers. It plays a crucial role in the thermodynamics of interstellar clouds, because of the gas-dust collisional coupling. It is also a key parameter in astrochemical studies that governs the rate at which molecules form on dust. In 3D (magneto)hydrodynamic simulations often a simple expression for the dust temperature is adopted, because of computational constraints, while astrochemical modelers tend to keep the dust temperature constant over a large range of parameter space. Our aim is to provide an easy-to-use parametric expression for the dust temperature as a function of visual extinction (AV) and to shed light on the critical dependencies of the dust temperature on the grain composition. We obtain an expression for the dust temperature by semi-analytically solving the dust thermal balance for different types of grains and compare to a collection of recent observational measurements. We also explore the effect of ices on the dust temperature. Our results show that a mixed carbonaceous-silicate type dust with a high carbon volume fraction matches the observations best. We find that ice formation allows the dust to be warmer by up to 15% at high optical depths (AV> 20 mag) in the interstellar medium. Our parametric expression for the dust temperature is presented as Td = [ 11 + 5.7 × tanh(0.61 - log 10(AV) ]χuv1/5.9, where χuv is in units of the Draine (1978, ApJS, 36, 595) UV field.

  8. Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Colorado and Utah using mobile stable isotope (13CH4) analysis

    Science.gov (United States)

    Rella, Chris; Jacobson, Gloria; Crosson, Eric; Karion, Anna; Petron, Gabrielle; Sweeney, Colm

    2013-04-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Because methane is more energy-rich than coal per kg of CO2 emitted into the atmosphere, it represents an attractive alternative to coal for electricity generation. However, given that the global warming potential of methane is many times greater than that of carbon dioxide (Solomon et al. 2007), the importance of quantifying the fugitive emissions of methane throughout the natural gas production and distribution process becomes clear (Howarth et al. 2011). A key step in the process of assessing the emissions arising from natural gas production activities is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One effective method for assessing the contribution of these different sources is stable isotope analysis. In particular, the 13CH4 signature of natural gas (-35 to -40 permil) is significantly different that the signature of other significant sources of methane, such as landfills or ruminants (-45 to -70 permil). In this paper we present measurements of mobile field 13CH4 using a spectroscopic stable isotope analyzer based on cavity ringdown spectroscopy, in two intense natural gas producing regions of the United States: the Denver-Julesburg basin in Colorado, and the Uintah basin in Utah. Mobile isotope measurements in the nocturnal boundary layer have been made, over a total path of 100s of km throughout the regions, allowing spatially resolved measurements of the regional isotope signature. Secondly, this analyzer was used to quantify the isotopic signature of those individual sources (natural gas fugitive emissions, concentrated animal feeding operations, and landfills) that constitute the majority of methane emissions in these regions, by making measurements of the isotope ratio directly in the downwind plume from each source. These

  9. Large aperture electrostatic dust detector

    International Nuclear Information System (INIS)

    Skinner, C.H.; Hensley, R.; Roquemore, A.L.

    2008-01-01

    Diagnosis and management of dust inventories generated in next-step magnetic fusion devices is necessary for their safe operation. A novel electrostatic dust detector, based on a fine grid of interlocking circuit traces biased to 30 or 50 V has been developed for the detection of dust particles on remote surfaces in air and vacuum environments. Impinging dust particles create a temporary short circuit and the resulting current pulse is recorded by counting electronics. Up to 90% of the particles are ejected from the grid or vaporized suggesting the device may be useful for controlling dust inventories. We report measurements of the sensitivity of a large area (5 x 5 cm) detector to microgram quantities of dust particles

  10. Large Aperture Electrostatic Dust Detector

    International Nuclear Information System (INIS)

    Skinner, C.H.; Hensley, R.; Roquemore, A.L.

    2007-01-01

    Diagnosis and management of dust inventories generated in next-step magnetic fusion devices is necessary for their safe operation. A novel electrostatic dust detector, based on a fine grid of interlocking circuit traces biased to 30 or 50 v has been developed for the detection of dust particles on remote surfaces in air and vacuum environments. Impinging dust particles create a temporary short circuit and the resulting current pulse is recorded by counting electronics. Up to 90% of the particles are ejected from the grid or vaporized suggesting the device may be useful for controlling dust inventories. We report measurements of the sensitivity of a large area (5x5 cm) detector to microgram quantities of dust particles and review its applications to contemporary tokamaks and ITER.

  11. Deuterium enrichment of interstellar dusts

    Science.gov (United States)

    Das, Ankan; Chakrabarti, Sandip Kumar; Majumdar, Liton; Sahu, Dipen

    2016-07-01

    High abundance of some abundant and simple interstellar species could be explained by considering the chemistry that occurs on interstellar dusts. Because of its simplicity, the rate equation method is widely used to study the surface chemistry. However, because the recombination efficiency for the formation of any surface species is highly dependent on various physical and chemical parameters, the Monte Carlo method is best suited for addressing the randomness of the processes. We carry out Monte-Carlo simulation to study deuterium enrichment of interstellar grain mantle under various physical conditions. Based on the physical properties, various types of clouds are considered. We find that in diffuse cloud regions, very strong radiation fields persists and hardly a few layers of surface species are formed. In translucent cloud regions with a moderate radiation field, significant number of layers would be produced and surface coverage is mainly dominated by photo-dissociation products such as, C, CH_3, CH_2D, OH and OD. In the intermediate dense cloud regions (having number density of total hydrogen nuclei in all forms ˜2 × 10^4 cm^{-3}), water and methanol along with their deuterated derivatives are efficiently formed. For much higher density regions (˜10^6 cm^{-3}), water and methanol productions are suppressed but surface coverage of CO, CO_2, O_2, O_3 are dramatically increased. We find a very high degree of fractionation of water and methanol. Observational results support a high fractionation of methanol but surprisingly water fractionation is found to be low. This is in contradiction with our model results indicating alternative routes for de-fractionation of water.

  12. Bakers' exposure to flour dust.

    Science.gov (United States)

    Kirkeleit, Jorunn; Hollund, Bjørg Eli; Riise, Trond; Eduard, Wijnand; Bråtveit, Magne; Storaas, Torgeir

    2017-02-01

    We aimed to characterize bakers' personal exposure to airborne flour dust with respect to the health-related aerosol fractions inhalable, extrathoracic, and thoracic dust, and to examine possible production-related determinants of dust exposure. Sixty-eight bakers from 7 bakeries in Bergen, Norway (2009-2012) participated in the exposure assessment, comprising full-shift personal samples of inhalable dust (n = 107) and thoracic dust (n = 61). The relation between possible determinants and exposure was estimated using mixed effects models, while associations between the various aerosol fractions across task groups and type of bakeries were described by Pearson's correlation coefficients. Bakers' overall geometric mean personal exposure to inhalable, extrathoracic, and thoracic dust were 2.6 mg/m 3 (95% CI: 2.0, 3.2), 2.2 mg/m 3 (95% CI: 1.9, 2.7), and 0.33 mg/m 3 (95% CI 0.3, 0.4), respectively. A total of 29% of the measurements of inhalable dust were above the Norwegian Occupational Exposure Limit of 3 mg/m 3 . The exposure variability of inhalable dust could not be explained by any of the examined production-related determinants, while the daily production volume explained 18% of the variance in thoracic dust exposure. Overall, the thoracic dust represented 15% of the inhalable dust, being rather stable across the production-related determinants. The overall correlation between inhalable and thoracic dust was nevertheless moderate (r = 0.52, p bakers (r = 0.62) and no correlation during dough forming (r = 0.01). Bakers are exposed to flour dust at a level that most likely represents an excess risk of developing chronic diseases of the respiratory system, and a decrease of present exposure level is imperative. Extrathoracic dust-likely the most relevant sub-fraction in respect to flour-induced sensitization and occupational rhinitis-represented the main proportion of the measured inhalable dust. The variation in correlation coefficients between the dust fractions

  13. Dust in cosmic plasma environments

    International Nuclear Information System (INIS)

    Mendis, D.A.

    1979-01-01

    Cosmic dust is invariably immersed in a plasma and a radiative environment. Consequently, it is charged to some electrostatic potential which depends on the properties of the environment as well as the nature of the dust. This charging affects the physical and dynamical properties of the dust. In this paper the basic aspects of this dust-plasma interaction in several cosmic environments - including planetary magnetospheres, the heliosphere and the interstellar medium - are discussed. The physical and dynamical consequences of the interaction, as well as the pertinent observational evidence, are reviewed. Finally, the importance of the surface charge during the condensation process in plasma environments is stressed. (Auth.)

  14. Growth hormone suppression test

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003376.htm Growth hormone suppression test To use the sharing features on this page, please enable JavaScript. The growth hormone suppression test determines whether growth hormone production is ...

  15. Dust coagulation in ISM

    Science.gov (United States)

    Chokshi, Arati; Tielens, Alexander G. G. M.; Hollenbach, David

    1989-01-01

    Coagulation is an important mechanism in the growth of interstellar and interplanetary dust particles. The microphysics of the coagulation process was theoretically analyzed as a function of the physical properties of the coagulating grains, i.e., their size, relative velocities, temperature, elastic properties, and the van der Waal interaction. Numerical calculations of collisions between linear chains provide the wave energy in individual particles and the spectrum of the mechanical vibrations set up in colliding particles. Sticking probabilities are then calculated using simple estimates for elastic deformation energies and for the attenuation of the wave energy due to absorption and scattering processes.

  16. Gravitational radiation from dust

    International Nuclear Information System (INIS)

    Isaacson, R.A.; Welling, J.S.; Winicour, J.

    1985-01-01

    A dust cloud is examined within the framework of the general relativistic characteristic initial value problem. Unique gravitational initial data are obtained by requiring that the space-time be quasi-Newtonian. Explicit calculations of metric and matter fields are presented, which include all post-Newtonian corrections necessary to discuss the major physical properties of null infinity. These results establish a curved space version of the Einstein quadrupole formula, in the form ''news function equals third time derivative of transverse quadrupole moment,'' for this system. However, these results imply that some weakened notion of asymptotic flatness is necessary for the description of quasi-Newtonian systems

  17. Dust confinement and dust acoustic waves in a magnetized plasma

    Science.gov (United States)

    Piel, A.

    2005-10-01

    Systematic laboratory experiments on dust acoustic waves require the confinement of dust particles. Here we report on new experiments in a magnetized plasma region in front of an additional positively biased disk electrode in a background plasma which is generated in argon at 27MHz between a disk and grid electrode. The plasma diffuses through the grid along the magnetic field. The three-dimensional dust distribution is measured with a horizontal sheet of laser light and a CCD camera, which are mounted on a vertical translation stage. Depending on magnetic field and discharge current, cigar or donut-shaped dust clouds are generated, which tend to rotate about the magnetic field direction. Measurements with emissive probes show that the axial confinement of dust particles with diameters between 0.7-2 μm is achieved by a balance of ion-drag force and electric field force. Dust levitation and radial confinement is due to a strong radial electric field. Dust acoustic waves are destabilized by the ion flow or can be stimulated by a periodic bias on the disk electrode. The observed wave dispersion is compared with fluid and kinetic models of the dust acoustic wave.

  18. Gravimetric dust sampling for control purposes and occupational dust sampling.

    CSIR Research Space (South Africa)

    Unsted, AD

    1997-02-01

    Full Text Available Prior to the introduction of gravimetric dust sampling, konimeters had been used for dust sampling, which was largely for control purposes. Whether or not absolute results were achievable was not an issue since relative results were used to evaluate...

  19. Of data and dust

    CERN Multimedia

    Stephanie Hills

    2016-01-01

    The traditional image of an archive is one of dusty old boxes, books and papers. When your archive is digital, dust spells disaster. An innovative environmental sensor designed and built by a CERN IT specialist has become an essential element in the Laboratory’s data-preservation strategy.   The novel air particle monitoring sensor designed by CERN's Julien Leduc. CERN’s archive holds more than 130 petabytes of data from past and present high-energy physics experiments. Some of it is 40 years old, most of it needs to be kept forever, and all of it is held on tape cartridges (over 20,000 of them). The cartridges are held inside tape libraries with robotic arms that load them into tape drives where they can be read and written. Tape cartridges have many advantages over other data storage media, notably cost and long-term reliability, but topping the list of drawbacks is their vulnerability to contamination from airborne dust particles; a tiny piece of g...

  20. Dust forecasting system in JMA

    International Nuclear Information System (INIS)

    Mikami, M; Tanaka, T Y; Maki, T

    2009-01-01

    JMAs dust forecasting information, which is based on a GCM dust model, is presented through the JMA website coupled with nowcast information. The website was updated recently and JMA and MOE joint 'KOSA' website was open from April 2008. Data assimilation technique will be introduced for improvement of the 'KOSA' information.

  1. Health hazards of cement dust

    International Nuclear Information System (INIS)

    Meo, Sultan A.

    2004-01-01

    ven in the 21st century, millions of people are working daily in a dusty environment. They are exposed to different types of health hazards such as fume, gases and dust, which are risk factors in developing occupational disease. Cement industry is involved in the development of structure of this advanced and modern world but generates dust during its production. Cement dust causes lung function impairment, chronic obstructive lung disease, restrictive lung disease, pneumoconiosis and carcinoma of the lungs, stomach and colon. Other studies have shown that cement dust may enter into the systemic circulation and thereby reach the essentially all the organs of body and affects the different tissues including heart, liver, spleen, bone, muscles and hairs and ultimately affecting their micro-structure and physiological performance. Most of the studies have been previously attempted to evaluate the effects of cement dust exposure on the basis of spirometry or radiology, or both. However, collective effort describing the general effects of cement dust on different organ and systems in humans or animals, or both has not been published. Therefore, the aim of this review is to gather the potential toxic effects of cement dust and to minimize the health risks in cement mill workers by providing them with information regarding the hazards of cement dust. (author)

  2. Parameterizing the interstellar dust temperature

    NARCIS (Netherlands)

    Hocuk, S.; Szűcs, L.; Caselli, P.; Cazaux, S.; Spaans, M.; Esplugues, G. B.

    2017-01-01

    The temperature of interstellar dust particles is of great importance to astronomers. It plays a crucial role in the thermodynamics of interstellar clouds, because of the gas-dust collisional coupling. It is also a key parameter in astrochemical studies that governs the rate at which molecules form

  3. 75 FR 3881 - Combustible Dust

    Science.gov (United States)

    2010-01-25

    ... Combustible Dust AGENCY: Occupational Safety and Health Administration (OSHA), Labor. ACTION: Notice of stakeholder meetings. SUMMARY: OSHA invites interested parties to participate in informal stakeholder meetings on the workplace hazards of combustible dust. OSHA plans to use the information gathered at these...

  4. 75 FR 10739 - Combustible Dust

    Science.gov (United States)

    2010-03-09

    ... Combustible Dust AGENCY: Occupational Safety and Health Administration (OSHA), Labor. ACTION: Notice of stakeholder meetings. SUMMARY: OSHA invites interested parties to participate in informal stakeholder meetings on the workplace hazards of combustible dust. OSHA plans to use the information gathered at these...

  5. Andromeda's dust

    Energy Technology Data Exchange (ETDEWEB)

    Draine, B. T.; Aniano, G. [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544-1001 (United States); Krause, Oliver; Groves, Brent; Sandstrom, Karin; Klaas, Ulrich; Linz, Hendrik; Rix, Hans-Walter; Schinnerer, Eva; Schmiedeke, Anika; Walter, Fabian [Max-Planck-Institut fur Astronomie, Konigstuhl 17, D-69117 Heidelberg (Germany); Braun, Robert [CSIRO—Astronomy and Space Science, P.O. Box 76, Epping, NWS 1710 (Australia); Leroy, Adam, E-mail: draine@astro.princeton.edu, E-mail: ganiano@ias.u-psud.fr [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)

    2014-01-10

    Spitzer Space Telescope and Herschel Space Observatory imaging of M31 is used, with a physical dust model, to construct maps of dust surface density, dust-to-gas ratio, starlight heating intensity, and polycyclic aromatic hydrocarbon (PAH) abundance, out to R ≈ 25 kpc. The global dust mass is M {sub d} = 5.4 × 10{sup 7} M {sub ☉}, the global dust/H mass ratio is M {sub d}/M {sub H} = 0.0081, and the global PAH abundance is (q {sub PAH}) = 0.039. The dust surface density has an inner ring at R = 5.6 kpc, a maximum at R = 11.2 kpc, and an outer ring at R ≈ 15.1 kpc. The dust/gas ratio varies from M {sub d}/M {sub H} ≈ 0.026 at the center to ∼0.0027 at R ≈ 25 kpc. From the dust/gas ratio, we estimate the interstellar medium metallicity to vary by a factor ∼10, from Z/Z {sub ☉} ≈ 3 at R = 0 to ∼0.3 at R = 25 kpc. The dust heating rate parameter (U) peaks at the center, with (U) ≈ 35, declining to (U) ≈ 0.25 at R = 20 kpc. Within the central kiloparsec, the starlight heating intensity inferred from the dust modeling is close to what is estimated from the stars in the bulge. The PAH abundance reaches a peak q {sub PAH} ≈ 0.045 at R ≈ 11.2 kpc. When allowance is made for the different spectrum of the bulge stars, q {sub PAH} for the dust in the central kiloparsec is similar to the overall value of q {sub PAH} in the disk. The silicate-graphite-PAH dust model used here is generally able to reproduce the observed dust spectral energy distribution across M31, but overpredicts 500 μm emission at R ≈ 2-6 kpc, suggesting that at R = 2-6 kpc, the dust opacity varies more steeply with frequency (with β ≈ 2.3 between 200 and 600 μm) than in the model.

  6. Dust in flowing magnetized plasma

    International Nuclear Information System (INIS)

    Pandey, Birendra P.; Samarian, Alex A.; Vladimirov, Sergey V.

    2009-01-01

    Plasma flows occur in almost every laboratory device and interactions of flowing plasmas with near-wall impurities and/or dust significantly affects the efficiency and lifetime of such devices. The charged dust inside the magnetized flowing plasma moves primarily under the influence of the plasma drag and electric forces. Here, the charge on the dust, plasma potential, and plasma density are calculated self-consistently. The electrons are assumed non-Boltzmannian and the effect of electron magnetization and electron-atom collisions on the dust charge is calculated in a self-consistent fashion. For various plasma magnetization parameters viz. the ratio of the electron and ion cyclotron frequencies to their respective collision frequencies, plasma-atom and ionization frequencies, the evolution of the plasma potential and density in the flow region is investigated. The variation of the dust charge profile is shown to be a sensitive function of plasma parameters. (author)

  7. Dust characterization in FTU tokamak

    Science.gov (United States)

    De Angeli, M.; Maddaluno, G.; Laguardia, L.; Ripamonti, D.; Perelli Cippo, E.; Apicella, M. L.; Conti, C.; Giacomi, G.; Grosso, G.

    2015-08-01

    Dust present in the vessel of FTU has been collected and analysed. Being FTU a device with full metal plasma facing components for the whole life and equipped with a liquid lithium limiter (LLL) make FTU of special interest from a point of view of dust studies. Analyses were conducted by standard dust analysis methods and by dedicated analysis, as X-rays and neutron diffraction, to investigate the presence of lithium compounds due the presence of the LLL in FTU. Dust collected near the LLL presents a different elemental composition, namely Li compounds, compared to the dust collected in the rest of the vessel; in particular LiO2, LiOH, and Li2CO3. On the basis of these results, the formation of Li2CO3 is proposed via a two steps process. Results of fuel retention measured by thermal desorption spectroscopy (TDS) method show that fuel retention should not be an issue for FTU.

  8. Fugitive coke oven gas emission profile by continuous line averaged open-path Fourier transform infrared monitoring.

    Science.gov (United States)

    Lin, Chitsan; Liou, Naiwei; Chang, Pao-Erh; Yang, Jen-Chin; Sun, Endy

    2007-04-01

    Although most coke oven research is focused on the emission of polycyclic aromatic hydrocarbons, well-known carcinogens, little has been done on the emission of volatile organic compounds, some of which are also thought to be hazardous to workers and the environment. To profile coke oven gas (COG) emissions, we set up an open-path Fourier transform infrared (OP-FTIR) system on top of a battery of coke ovens at a steel mill located in Southern Taiwan and monitored average emissions in a coke processing area for 16.5 hr. Nine COGs were identified, including ammonia, CO, methane, ethane, ethylene, acetylene, propylene, cyclohexane, and O-xylene. Time series plots indicated that the type of pollutants differed over time, suggesting that different emission sources (e.g., coke pushing, quench tower, etc.) were involved at different times over the study period. This observation was confirmed by the low cross-correlation coefficients of the COGs. It was also found that, with the help of meteorological analysis, the data collected by the OP-FTIR system could be analyzed effectively to characterize differences in the location of sources. Although the traditional single-point samplings of emissions involves sampling various sources in a coke processing area at several different times and is a credible profiling of emissions, our findings strongly suggest that they are not nearly as efficient or as cost-effective as the continuous line average method used in this study. This method would make it easier and cheaper for engineers and health risk assessors to identify and to control fugitive volatile organic compound emissions and to improve environmental health.

  9. THE ROLE OF DUST IN THE EARLY UNIVERSE. I. PROTOGALAXY EVOLUTION

    International Nuclear Information System (INIS)

    Yamasawa, Daisuke; Habe, Asao; Kozasa, Takashi; Nozawa, Takaya; Nomoto, Ken'ichi; Hirashita, Hiroyuki; Umeda, Hideyuki

    2011-01-01

    We develop one-zone galaxy formation models in the early universe, taking into account dust formation and evolution by supernova (SN) explosions. We focus on the time evolution of dust size distribution, because H 2 formation on the dust surface plays a critical role in the star formation process in the early universe. In the model, we assume that star formation rate (SFR) is proportional to the total amount of H 2 . We consistently treat (1) the formation and size evolution of dust, (2) the chemical reaction networks including H 2 formation both on the surface of dust and in gas phase, and (3) the SFR in the model. First, we find that, because of dust destruction due to both reverse and forward shocks driven by SNe, H 2 formation is more suppressed than in situations without such dust destruction. At the galaxy age of ∼0.8 Gyr, for galaxy models with virial mass M vir = 10 9 M sun and formation redshift z vir = 10, the molecular fraction is 2.5 orders of magnitude less in the model with dust destruction by both shocks than that in the model without dust destruction. Second, we show that the H 2 formation rate strongly depends on the interstellar medium (ISM) density around SN progenitors. The SFR in higher ISM density is lower, since dust destruction by reverse shocks is more effective in higher ISM density. We conclude that not only the amount but also the size distribution of dust related to star formation activity strongly affects the evolution of galaxies in the early universe.

  10. Dust in protoplanetary disks: observations*

    Directory of Open Access Journals (Sweden)

    Waters L.B.F.M.

    2015-01-01

    Full Text Available Solid particles, usually referred to as dust, are a crucial component of interstellar matter and of planet forming disks surrounding young stars. Despite the relatively small mass fraction of ≈1% (in the solar neighborhood of our galaxy; this number may differ substantially in other galaxies that interstellar grains represent of the total mass budget of interstellar matter, dust grains play an important role in the physics and chemistry of interstellar matter. This is because of the opacity dust grains at short (optical, UV wavelengths, and the surface they provide for chemical reactions. In addition, dust grains play a pivotal role in the planet formation process: in the core accretion model of planet formation, the growth of dust grains from the microscopic size range to large, cm-sized or larger grains is the first step in planet formation. Not only the grain size distribution is affected by planet formation. Chemical and physical processes alter the structure and chemical composition of dust grains as they enter the protoplanetary disk and move closer to the forming star. Therefore, a lot can be learned about the way stars and planets are formed by observations of dust in protoplanetary disks. Ideally, one would like to measure the dust mass, the grain size distribution, grain structure (porosity, fluffiness, the chemical composition, and all of these as a function of position in the disk. Fortunately, several observational diagnostics are available to derive constrains on these quantities. In combination with rapidly increasing quality of the data (spatial and spectral resolution, a lot of progress has been made in our understanding of dust evolution in protoplanetary disks. An excellent review of dust evolution in protoplanetary disks can be found in Testi et al. (2014.

  11. Graphic products used in the evaluation of traditional and emerging remote sensing technologies for the detection of fugitive contamination at selected superfund hazardous waste sites

    Science.gov (United States)

    Slonecker, E. Terrence; Fisher, Gary B.

    2011-01-01

    This report presents the overhead imagery and field sampling results used to prepare U.S. Geological Survey Open-File Report 2011-1050, 'Evaluation of Traditional and Emerging Remote Sensing Technologies for the Detection of Fugitive Contamination at Selected Superfund Hazardous Waste Sites'. These graphic products were used in the evaluation of remote sensing technology in postclosure monitoring of hazardous waste sites and represent an ongoing research effort. Soil sampling results presented here were accomplished with field portable x-ray fluoresence (XRF) technology and are used as screening tools only representing the current conditions of metals and other contaminants at selected Superfund hazardous waste sites.

  12. Nonlinear screening of dust grains and structurization of dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Tsytovich, V. N., E-mail: tsytov@lpi.ru; Gusein-zade, N. G. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2013-07-15

    equilibrium between plasma components when analyzing equilibrium structures. The effect of plasma screening nonlinearity on both the diffusion processes and the forces of dust drag by plasma fluxes is analyzed. It is shown how self-organized dust structures form in these processes. In the limit of very small dust grain charges, the forces acting on the dusty plasma components and the set of basic equations for stationary dust structures (with allowance for nonlinear screening) take a standard form. New qualitative effects, such as the suppression of diffusion due to ion scattering from dust grains and the formation of structures of different configurations, are described. A detailed comparison with previous results is performed. It is shown that the solution of basic nonlinear equations for dust structures yields new qualitative effects. A number of new effects to be studied in future dusty plasma experiments with the formation of structures in spherical chambers are predicted (it is assumed that diffusion will play a significant role under microgravity conditions). Recent ground-based experiments, as well as experiments carried out onboard the International Space Station, directly confirm the nonlinear character of screening and the significant role played by this nonlinearity in the structurization of dusty plasma. Experiments on the formation of structures consisting of smaller dust grains within structures formed of larger grains are discussed. It is shown that those experiments can be interpreted only using the concept of nonlinear screening.

  13. COLLIDING DECIMETER DUST

    Energy Technology Data Exchange (ETDEWEB)

    Deckers, J.; Teiser, J., E-mail: johannes.deckers@uni-due.de [Fakultaet fuer Physik, Universitaet Duisburg-Essen, D-47057 Duisburg (Germany)

    2013-06-01

    Collisional evolution is a key process in planetesimal formation and decimeter bodies play a key role in the different models. However, the outcome of collisions between two dusty decimeter bodies has never been studied experimentally. Therefore, we carried out microgravity collision experiments in the Bremen drop tower. The agglomerates consist of quartz with irregularly shaped micrometer-sized grains and the mean volume filling factor is 0.437 {+-} 0.004. The aggregates are cylindrical with 12 cm in height and 12 cm in diameter, and typical masses are 1.5 kg. These are the largest and most massive dust aggregates studied in collisions to date. We observed rebound and fragmentation but no sticking in the velocity range between 0.8 and 25.7 cm s{sup -1}. The critical fragmentation velocity for split up of an aggregate is 16.2 {+-} 0.4 cm s{sup -1}. At lower velocities the aggregates bounce off each other. In this velocity range, the coefficient of restitution decreases with increasing collision velocity from 0.8 to 0.3. While the aggregates are very weak, the critical specific kinetic energy for fragmentation Q{sub {mu}=1} is a factor of six larger than expected. Collisions of large bodies in protoplanetary disks are supposed to be much faster and the generation of smaller fragments is likely. In planetary rings, collision velocities are of the order of a few cm s{sup -1} and are thereby in the same range investigated in these experiments. The coefficient of restitution of dust agglomerates and regolith-covered ice particles, which are common in planetary rings, are similar.

  14. Ulysses dust measurements near Jupiter.

    Science.gov (United States)

    Grün, E; Zook, H A; Baguhl, M; Fechtig, H; Hanner, M S; Kissel, J; Lindblad, B A; Linkert, D; Linkert, G; Mann, I B

    1992-09-11

    Submicrometer- to micrometer-sized particles were recorded by the Ulysses dust detector within 40 days of the Jupiter flyby. Nine impacts were recorded within 50 Jupiter radii with most of them recorded after closest approach. Three of these impacts are consistent with particles on prograde orbits around Jupiter and the rest are believed to have resulted from gravitationally focused interplanetary dust. From the ratio of the impact rate before the Jupiter flyby to the impact rate after the Jupiter flyby it is concluded that interplanetary dust particles at the distance of Jupiter move on mostly retrograde orbits. On 10 March 1992, Ulysses passed through an intense dust stream. The dust detector recorded 126 impacts within 26 hours. The stream particles were moving on highly inclined and apparently hyperbolic orbits with perihelion distances of >5 astronomical units. Interplanetary dust is lost rather quickly from the solar system through collisions and other mechanisms and must be almost continuously replenished to maintain observed abundances. Dust flux measurements, therefore, give evidence of the recent rates of production from sources such as comets, asteroids, and moons, as well as the possible presence of interstellar grains.

  15. Dust Around T Tauri Stars

    Directory of Open Access Journals (Sweden)

    Kyung-Won Suh

    2011-12-01

    Full Text Available To reproduce the multiple broad peaks and the fine spectral features in the spectral energy distributions (SEDs of T Tauri stars, we model dust around T Tauri stars using a radiative transfer model for multiple isothermal circumstellar dust shells. We calculate the radiative transfer model SEDs for multiple dust shells using the opacity functions for various dust grains at different temperatures. For six sample stars, we compare the model results with the observed SEDs including the Spitzer spectral data. We present model parameters for the best fit model SEDs that would be helpful to understand the overall structure of dust envelopes around classical T Tauri stars. We find that at least three separate dust components are required to reproduce the observed SEDs. For all the sample stars, an innermost hot (250-550 K dust component of amorphous (silicate and carbon and crystalline (corundum for all objects and forsterite for some objects grains is needed. Crystalline forsterite grains can reproduce many fine spectral features of the sample stars. We find that crystalline forsterite grains exist in cold regions (80-100 K as well as in hot inner shells.

  16. Triton's streaks as windblown dust

    Science.gov (United States)

    Sagan, Carl; Chyba, Christopher

    1990-01-01

    Explanations for the surface streaks observed by Voyager 2 on Triton's southern hemisphere are discussed. It is shown that, despite Triton's tenuous atmosphere, low-cohesion dust trains with diameters of about 5 micron or less may be carried into suspension by aeolian surface shear stress, given expected geostrophic wind speeds of about 10 m/s. For geyser-like erupting dust plumes, it is shown that dust-settling time scales and expected wind velocities can produce streaks with length scales in good agreement with those of the streaks. Thus, both geyserlike eruptions or direct lifting by surface winds appear to be viable mechanisms for the origin of the streaks.

  17. Dust Dynamics Near Planetary Surfaces

    Science.gov (United States)

    Colwell, Joshua; Hughes, Anna; Grund, Chris

    Observations of a lunar "horizon glow" by several Surveyor spacecraft in the 1960s opened the study of the dynamics of charged dust particles near planetary surfaces. The surfaces of the Moon and other airless planetary bodies in the solar system (asteroids, and other moons) are directly exposed to the solar wind and ionizing solar ultraviolet radiation, resulting in a time-dependent electric surface potential. Because these same objects are also exposed to bombardment by micrometeoroids, the surfaces are usually characterized by a power-law size distribution of dust that extends to sub-micron-sized particles. Individual particles can acquire a charge different from their surroundings leading to electrostatic levitation. Once levitated, particles may simply return to the surface on nearly ballistic trajectories, escape entirely from the moon or asteroid if the initial velocity is large, or in some cases be stably levitated for extended periods of time. All three outcomes have observable consequences. Furthermore, the behavior of charged dust near the surface has practical implications for planned future manned and unmanned activities on the lunar surface. Charged dust particles also act as sensitive probes of the near-surface plasma environment. Recent numerical modeling of dust levitation and transport show that charged micron-sized dust is likely to accumulate in topographic lows such as craters, providing a mechanism for the creation of dust "ponds" observed on the asteroid 433 Eros. Such deposition can occur when particles are supported by the photoelectron sheath above the dayside and drift over shadowed regions of craters where the surface potential is much smaller. Earlier studies of the lunar horizon glow are consistent with those particles being on simple ballistic trajectories following electrostatic launching from the surface. Smaller particles may be accelerated from the lunar surface to high altitudes consistent with observations of high altitude

  18. 30 CFR 75.402 - Rock dusting.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Rock dusting. 75.402 Section 75.402 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Combustible Materials and Rock Dusting § 75.402 Rock dusting... or too high in incombustible content to propagate an explosion, shall be rock dusted to within 40...

  19. PERSPECTIVE: Dust, fertilization and sources

    Science.gov (United States)

    Remer, Lorraine A.

    2006-11-01

    Aerosols, tiny suspended particles in the atmosphere, play an important role in modifying the Earth's energy balance and are essential for the formation of cloud droplets. Suspended dust particles lifted from the world's arid regions by strong winds contain essential minerals that can be transported great distances and deposited into the ocean or on other continents where productivity is limited by lack of usable minerals [1]. Dust can transport pathogens as well as minerals great distance, contributing to the spread of human and agricultural diseases, and a portion of dust can be attributed to human activity suggesting that dust radiative effects should be included in estimates of anthropogenic climate forcing. The greenish and brownish tints in figure 1 show the wide extent of monthly mean mineral dust transport, as viewed by the MODerate resolution Imaging Spectroradiometer (MODIS) satellite sensor. The monthly mean global aerosol system for February 2006 from the MODIS aboard the Terra satellite Figure 1. The monthly mean global aerosol system for February 2006 from the MODIS aboard the Terra satellite. The brighter the color, the greater the aerosol loading. Red and reddish tints indicate aerosol dominated by small particles created primarily from combustion processes. Green and brownish tints indicate larger particles created from wind-driven processes, usually transported desert dust. Note the bright green band at the southern edge of the Saharan desert, the reddish band it must cross if transported to the southwest and the long brownish transport path as it crosses the Atlantic to South America. Image courtesy of the NASA Earth Observatory (http://earthobservatory.nasa.gov). Even though qualitatively we recognize the extent and importance of dust transport and the role that it plays in fertilizing nutrient-limited regions, there is much that is still unknown. We are just now beginning to quantify the amount of dust that exits one continental region and the

  20. [Protecting Safety During Dust Fires and Dust Explosions - The Example of the Formosa Fun Coast Water Park Accident].

    Science.gov (United States)

    Hsieh, Ming-Hong; Wu, Jia-Wun; Li, Ya-Cing; Tang, Jia-Suei; Hsieh, Chun-Chien

    2016-02-01

    This paper will explore the fire and explosion characteristics of cornstarch powder as well as strategies for protecting the safety of people who are involved a dust fire or dust explosion. We discuss the 5 elements of dust explosions and conduct tests to analyze the fire and explosion characteristics of differently colored powders (yellow, golden yellow, pink, purple, orange and green). The results show that, while all of the tested powders were difficult to ignite, low moisture content was associated with significantly greater risks of ignition and flame spread. We found the auto-ignition temperature (AIT) of air-borne cornstarch powder to be between 385°C and 405°C, with yellow-colored cornstarch powder showing the highest AIT and pink-colored cornstarch powder showing the lowest AIT. The volume resistivity of all powder samples was approximately 108 Ω.m, indicating that they were nonconductive. Lighters and cigarettes are effective ignition sources, as their lit temperatures are higher than the AIT of cornstarch powder. In order to better protect the safety of individuals at venues where cornstarch powder is released, explosion control measures such as explosion containment facilities, vents, and explosion suppression and isolation devices should be installed. Furthermore, employees that work at these venues should be better trained in explosion prevention and control measures. We hope this article is a reminder to the public to recognize the fire and explosion characteristics of flammable powders as well as the preventive and control measures for dust explosions.

  1. First Real-Time Detection of Surface Dust in a Tokamak

    International Nuclear Information System (INIS)

    Skinner, C.; Rais, B.; Roquemore, A.L.; Kugel, H.W.; Marsala, R.; Provost, T.

    2010-01-01

    The first real-time detection of surface dust inside a tokamak was made using an electrostatic dust detector. A fine grid of interlocking circuit traces was installed in the NSTX vessel and biased to 50 v. Impinging dust particles created a temporary short circuit and the resulting current pulse was recorded by counting electronics. The techniques used to increase the detector sensitivity by a factor of x10,000 to match NSTX dust levels while suppressing electrical pickup are presented. The results were validated by comparison to lab measurements, by the null signal from a covered detector that was only sensitive to pickup, and by the dramatic increase in signal when Li particles were introduced for wall conditioning purposes.

  2. First Real-Time Detection of Surface Dust in a Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, C.; Rais, B.; Roquemore, A. L.; Kugel, H. W.; Marsala, R.; Provost, T.

    2010-05-20

    The first real-time detection of surface dust inside a tokamak was made using an electrostatic dust detector. A fine grid of interlocking circuit traces was installed in the NSTX vessel and biased to 50 v. Impinging dust particles created a temporary short circuit and the resulting current pulse was recorded by counting electronics. The techniques used to increase the detector sensitivity by a factor of x10,000 to match NSTX dust levels while suppressing electrical pickup are presented. The results were validated by comparison to lab measurements, by the null signal from a covered detector that was only sensitive to pickup, and by the dramatic increase in signal when Li particles were introduced for wall conditioning purposes.

  3. Regarding Electrified Martian Dust Storms

    Science.gov (United States)

    Farrell, W. M.

    2017-06-01

    We examine the dynamic competition between dust devil/storm charging currents and dissipating atmospheric currents. A question: Can high-current lightning be a dissipation product of this competition? Most likely not but there are exceptions.

  4. Loess and Eolian Dust Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past environment derived from Loess and Eolian dust (silt-sized material deposited on the Earth surface by the surface winds. Parameter keywords describe...

  5. The impact of the Pacific Decadal Oscillation on springtime dust activity in Syria

    Directory of Open Access Journals (Sweden)

    B. Pu

    2016-10-01

    Full Text Available The increasing trend of aerosol optical depth in the Middle East and a recent severe dust storm in Syria have raised questions as to whether dust storms will increase and promoted investigations on the dust activities driven by the natural climate variability underlying the ongoing human perturbations such as the Syrian civil war. This study examined the influences of the Pacific Decadal Oscillation (PDO on dust activities in Syria using an innovative dust optical depth (DOD dataset derived from Moderate Resolution Imaging Spectroradiometer (MODIS Deep Blue aerosol products. A significantly negative correlation is found between the Syrian DOD and the PDO in spring from 2003 to 2015. High DOD in spring is associated with lower geopotential height over the Middle East, Europe, and North Africa, accompanied by near-surface anomalous westerly winds over the Mediterranean basin and southerly winds over the eastern Arabian Peninsula. These large-scale patterns promote the formation of the cyclones over the Middle East to trigger dust storms and also facilitate the transport of dust from North Africa, Iraq, and Saudi Arabia to Syria, where the transported dust dominates the seasonal mean DOD in spring. A negative PDO not only creates circulation anomalies favorable to high DOD in Syria but also suppresses precipitation in dust source regions over the eastern and southern Arabian Peninsula and northeastern Africa.On the daily scale, in addition to the favorable large-scale condition associated with a negative PDO, enhanced atmospheric instability in Syria (associated with increased precipitation in Turkey and northern Syria is also critical for the development of strong springtime dust storms in Syria.

  6. The impact of Pacific Decadal Oscillation on springtime dust activity in Syria

    Science.gov (United States)

    Pu, B.; Ginoux, P. A.

    2016-12-01

    The increasing trend of aerosol optical depth in the Middle East and a recent severe dust storm in Syria have raised questions as whether dust storms will increase and promoted investigations on the dust activities driven by the natural climate variability underlying the ongoing human perturbations such as the Syrian civil war. This study examined the influences of the Pacific decadal oscillation (PDO) on dust activities in Syria using an innovative dust optical depth (DOD) dataset derived from Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue aerosol products. A significantly negative correlation is found between the Syrian DOD and the PDO in spring from 2003-2015. High DOD in spring is associated with lower geopotential height over the Middle East, Europe, and North Africa, accompanied by near surface anomalous westerly winds over the Mediterranean basin and southerly winds over the eastern Arabian Peninsula. These large-scale patterns promote the formation of the cyclones over the Middle East to trigger dust storms and also facilitate the transport of dust from North Africa, Iraq, and Saudi Arabian to Syria, where the transported dust dominates the seasonal mean DOD in spring. A negative PDO not only creates circulation anomalies favorable to high DOD in Syria but also suppresses precipitation in dust source regions over the eastern and southern Arabian Peninsula and northeastern Africa. On the daily scale, in addition to the favorable large-scale condition associated with a negative PDO, enhanced atmospheric instability in Syria associated with increased precipitation in Turkey and northern Syria is also critical for the development of strong springtime dust storms in Syria.

  7. The impact of the Pacific Decadal Oscillation on springtime dust activity in Syria

    Science.gov (United States)

    Pu, Bing; Ginoux, Paul

    2016-10-01

    The increasing trend of aerosol optical depth in the Middle East and a recent severe dust storm in Syria have raised questions as to whether dust storms will increase and promoted investigations on the dust activities driven by the natural climate variability underlying the ongoing human perturbations such as the Syrian civil war. This study examined the influences of the Pacific Decadal Oscillation (PDO) on dust activities in Syria using an innovative dust optical depth (DOD) dataset derived from Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue aerosol products. A significantly negative correlation is found between the Syrian DOD and the PDO in spring from 2003 to 2015. High DOD in spring is associated with lower geopotential height over the Middle East, Europe, and North Africa, accompanied by near-surface anomalous westerly winds over the Mediterranean basin and southerly winds over the eastern Arabian Peninsula. These large-scale patterns promote the formation of the cyclones over the Middle East to trigger dust storms and also facilitate the transport of dust from North Africa, Iraq, and Saudi Arabia to Syria, where the transported dust dominates the seasonal mean DOD in spring. A negative PDO not only creates circulation anomalies favorable to high DOD in Syria but also suppresses precipitation in dust source regions over the eastern and southern Arabian Peninsula and northeastern Africa.On the daily scale, in addition to the favorable large-scale condition associated with a negative PDO, enhanced atmospheric instability in Syria (associated with increased precipitation in Turkey and northern Syria) is also critical for the development of strong springtime dust storms in Syria.

  8. Preliminary analysis of hydrogen risk caused by dust in ITER

    International Nuclear Information System (INIS)

    Cheng Kun; Tong Lili; Cao Xuewu

    2012-01-01

    A lot of dust will be generated during ITER operation,and hydrogen will be produced by the interaction of hot dust with water in the case of coolant ingress accident. The accumulated hydrogen will bring risk of combustion and explosion,which will damage the device. CFD method has been used to analyze the produced hydrogen in 'wet bypass' scenario, and come to the results that hydrogen will burn and explode at the beginning of the accident, different hydrogen risk will be brought by different coolant leakage, and hydrogen risk will be inert if the leakage is massive.Injecting CO 2 to inert the vacuum vessel has also been discussed, the risk of hydrogen will be suppressed by injecting CO 2 with a large rate at the beginning of accident. (authors)

  9. Dust Availability in Desert Terrains

    Science.gov (United States)

    1985-01-01

    RAVIKOVIrCIl, 1953: KAPLAN , 19119. Si ATKINE. 1960). From Yaalon & Ginzhourg (1988). B.8 AMOUNTS AND CONCENTRATIONS OFl DUST IN THE ATMOSPHERE (see also...deposits of comparable origin and age further north along the Dead Sea Rift. Another exampie is the lava flows of latest Pleisto- cene age in the Cima ...the Cima Volcanic Field in the southern Mojave Desert, located downwind of extensive dust-producing playa surfaces. More than 1 m of a gravel-free B

  10. Pressure suppression device

    International Nuclear Information System (INIS)

    Ichiki, Tadaharu; Funahashi, Toshihiro.

    1976-01-01

    Purpose: To provide a structure which permits the absorption of shocks and vibratory load produced on the floor of a pressure suppression chamber due to nitrogen gas or the like discharged into pool water in the pressure suppression chamber at the time of a loss-of-coolant accident. Constitution: A pressure suppression chamber accommodating pool water is comprised of a bottom wall and side walls constructed of concrete on the inner side of a liner. By providing concrete on the bottom surface and side wall surfaces of a pressure suppression chamber, it is possible to prevent non-condensing gas and steam exhausted from the vent duct and exhaust duct of a main vapor escapement safety valve exhaust duct from exerting impact forces and vibratory forces upon the bottom and side surfaces of the pressure suppression chamber. (Horiuchi, T.)

  11. Suspended dust in Norwegian cities

    International Nuclear Information System (INIS)

    2001-01-01

    According to calculations, at least 80 000 people in Oslo and 8 000 in Trondheim were annoyed by too much suspended dust in 2000. The dust concentration is greatest in the spring, presumably because dust is swirling up from melting snow and ice on the streets. Car traffic is the main source of the dust, except for some of the most highly exposed regions where wood-firing from old stoves contributes up to 70 percent of the dust. National targets for air quality include suspended dust, nitrogen dioxide, sulphur dioxide and benzene. Calculations show that nitrogen dioxide emissions exceeding the limit affected 4 000 people in Oslo and 1 000 people in Trondheim. The sulphur dioxide emissions in the major cities did non exceed the national quality limit; they did exceed the limit in some of the smaller industrial centres. In Trondheim, measurements show that the national limit for benzene was exceeded. Most of the emission of nitrogen dioxide comes from the road traffic. Local air pollution at times causes considerable health- and well-being problems in the larger cities and industrial centres, where a great part of the population may be at risk of early death, infection of the respiratory passage, heart- and lung diseases and cancer

  12. Numerical Simulation of the Direct Radiative Effects of Dust Aerosol on the East Asian Winter Monsoon

    Directory of Open Access Journals (Sweden)

    Hui Sun

    2015-01-01

    Full Text Available Variations of the East Asian winter monsoon (EAWM induced by dust aerosol are studied by using a regional climate model (RegCM4/Dust. Dust coupled and uncoupled experiments are carried out for the past decade (2000–2009. The coupled RegCM4 captures three centers of dust mixing ratio (DMR located in the Taklamakan Desert, western Inner Mongolia, and northern Xinjiang, respectively, with maximum values greater than 500 µg kg−1 in winter. The surface total radiation change induced by dust is negative, and its central value of −8 W m−2 results in surface temperature cooling by 1.5°C in winter. Dust induced radiation change at the top of the atmosphere (TOA is also negative in Northern China, except over the Tibetan Plateau (TP, and up to −5 W m−2 in Central China. Dust cooling effects increase the sea level pressure (SLP gradient between land and ocean, the cold surge frequency, and the East Asian jet stream (EAJ intensity and then enhance the EAWM. The dry and cold wind pervade most areas of East Asia, suppressing large-scale precipitation and eventually leading to a rainfall decrease of about 10–30% in Northern China and the middle Yangtze River Valley.

  13. Dust Particle Size Distributions during Spring in Yinchuan, China

    OpenAIRE

    Jiangfeng Shao; Jiandong Mao

    2016-01-01

    Dust particle size distributions in Yinchuan, China, were measured during March and April 2014, using APS-3321 sampler. The distributions were measured under different dust conditions (background, floating dust, blowing dust, and dust storm) and statistical analyses were performed. The results showed that, under different dust conditions, the instantaneous number concentrations of dust particles differed widely. For example, during blowing sand and dust storm conditions, instantaneous dust pa...

  14. Identifying Biases in Dust Source Functions

    Science.gov (United States)

    Evan, A. T.; Wang, W.; Zhao, C.

    2017-12-01

    The Sahara is the largest desert in the world and accounts for more than 50% of global dust emission. However, it is difficult to identify dust source regions as the Sahara is vastly uninhabited. In order to model North African dust, previous works have used satellite data to construct so-called dust source functions. Here we examine such dust source function using output from multi-year runs with the Weather Research and Forecasting with Chemistry (WRF-Chem) model. We find that dust source functions based on satellite data overestimate DOD in the Sahel and the western Sahara region. To eliminate the biases of the dust source function due to advection, we develop a new source function using DOD in the lowest 1 km from the model. This work suggests that dust source functions constructed with satellite retrievlas of optical depth may overestimate dust emission in the downwind regions and DOD may not be a good proxy for the source function.

  15. Interplanetary Dust Particles

    Science.gov (United States)

    Bradley, J. P.

    2003-12-01

    One of the fundamental goals of the study of meteorites is to understand how the solar system and planetary systems around other stars formed. It is known that the solar system formed from pre-existing (presolar) interstellar dust grains and gas. The grains originally formed in the circumstellar outflows of other stars. They were modified to various degrees, ranging from negligible modification to complete destruction and reformation during their ˜108 yr lifetimes in the interstellar medium (ISM) (Seab, 1987; Mathis, 1993). Finally, they were incorporated into the solar system. Submicrometer-sized silicates and carbonaceous material are believed to be the most common grains in the ISM ( Mathis, 1993; Sandford, 1996), but it is not known how much of this presolar particulate matter was incorporated into the solar system, to what extent it has survived, and how it might be distinguished from solar system grains. In order to better understand the process of solar system formation, it is important to identify and analyze these solid grains. Since all of the alteration processes that modified solids in the solar nebula presumably had strong radial gradients, the logical place to find presolar grains is in small primitive bodies like comets and asteroids that have undergone little, if any, parent-body alteration.Trace quantities of refractory presolar grains (e.g., SiC and Al2O3) survive in the matrices of the most primitive carbon-rich chondritic meteorites (Anders and Zinner, 1993; Bernatowicz and Zinner, 1996; Bernatowicz and Walker, 1997; Hoppe and Zinner, 2000; see Chapter 1.02). Chondritic meteorites are believed to be from the asteroid belt, a narrow region between 2.5 and 3.5 astronomical units (AU) that marks the transition from the terrestrial planets to the giant gas-rich planets. The spectral properties of the asteroids suggest a gradation in properties with some inner and main belt C and S asteroids (the source region of most meteorites and polar

  16. Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Weld County Colorado using δ13CH4 analysis

    Science.gov (United States)

    Rella, C.; Jacobson, G. A.; Crosson, E.; Sweeney, C.; Karion, A.; Petron, G.

    2012-12-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Given that the global warming potential of methane is many times greater than that of carbon dioxide (Forster et al. 2007), the importance of quantifying methane emissions becomes clear. Companion presentations at this meeting describe efforts to quantify the overall methane emissions in two separate gas producing areas in Colorado and Utah during intensive field campaigns undertaken in 2012. A key step in the process of assessing the emissions arising from natural gas production activities is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One method for assessing the contribution of these different sources is stable isotope analysis. In particular, the δ13CH4 signature of natural gas (-37 permil) is significantly different that the signature of other significant sources of methane, such as landfills or ruminants (-50 to -70 permil). In this paper we present measurements of δ13CH4 in Colorado in Weld County, a region of intense natural gas production, using a mobile δ13CH4¬ analyzer capable of high-precision measurements of the stable isotope ratio of methane at ambient levels. This analyzer was used to make stable isotope measurements at a fixed location near the center of the gas producing region, from which an overall isotope ratio for the regional emissions is determined. In addition, mobile measurements in the nocturnal boundary layer have been made, over a total distance of 150 km throughout Weld County, allowing spatially resolved measurements of this isotope signature. Finally, this analyzer was used to quantify the isotopic signature of those individual sources (natural gas fugitive emissions, concentrated animal feeding operations, and landfills) that constitute the majority of methane emissions in this region, by making

  17. Spring Dust Storm Smothers Beijing

    Science.gov (United States)

    2002-01-01

    A few days earlier than usual, a large, dense plume of dust blew southward and eastward from the desert plains of Mongolia-quite smothering to the residents of Beijing. Citizens of northeastern China call this annual event the 'shachenbao,' or 'dust cloud tempest.' However, the tempest normally occurs during the spring time. The dust storm hit Beijing on Friday night, March 15, and began coating everything with a fine, pale brown layer of grit. The region is quite dry; a problem some believe has been exacerbated by decades of deforestation. According to Chinese government estimates, roughly 1 million tons of desert dust and sand blow into Beijing each year. This true-color image was made using two adjacent swaths (click to see the full image) of data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), flying aboard the OrbView-2 satellite, on March 17, 2002. The massive dust storm (brownish pixels) can easily be distinguished from clouds (bright white pixels) as it blows across northern Japan and eastward toward the open Pacific Ocean. The black regions are gaps between SeaWiFS' viewing swaths and represent areas where no data were collected. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  18. Charged dust in saturn's magnetosphere

    International Nuclear Information System (INIS)

    Mendis, D.A.; Hill, J.R.; Houpis, H.L.F.

    1983-01-01

    Gravito-electrodynamic theory of charged dust grains is used to explain a variety of phenomena in those portions of the Saturnian ring system that are known to be dominated by fine (micron- and submicron-sized) dust, and in which collisional forces and Coulomb drag can be neglected. Among the phenomena discussed are the formation and evolution of the rotating near-radial spokes in the B-ring, the formation of waves in the F-ring, the cause of eccentricities of certain isolated ringlets, and the origin and morphology of the broad diffuse E-ring. Several novel processes predicted by the gravitoelectrodynamic theory, including 'magneto-gravitational capture' of exogenic dust by the magnetosphere, '1:1 magneto-gravitational orbital resonances' of charged dust with nearby satellites, and 'gyro-orbital resonances,' are used to explain individual observations. The effect of a ring current associated with this charged dust is also evaluated. Finally, the cosmogonic implications of the magneto-gravitational theory are briefly discussed. While several (although not all) of these processes have been discussed by one or more of the present authors elsewhere, the purpose of this paper is to synthesize all these processes within the framework of gravito-electrodynamics, and also to show its range of applicability within Saturn's ring system

  19. Constraints on astronomical silicate dust

    International Nuclear Information System (INIS)

    Sorrell, W.H.

    1990-01-01

    Numerical radiative-transfer models are used to discuss the properties of circumstellar dust grains around the premain-sequence star AB Aur (HD 31293). It is assumed that the dust consists of a silicate-graphite mixture with Draine and Lee (1984) optical properties. The modeling technique is to match the observed FUV through FIR energy distribution with the spectral energy distribution predicted for a spherical dust shell around a luminous hot star. Special attention is given to matching the observed 10-micron silicate emission feature and the observed circumstellar absorption curve at UV wavelengths, making it possible to strengthen constraints on dust-grain opacity and chemical composition. It is concluded that, although silicate grains can explain the observed 10-micron emission feature, the Draine and Lee silicate-graphite mixture cannot explain the observed FUV circumstellar absorption at the same time. The dust shell around AB Aur contains an additional population of small particles, the most likely candidate being amorphous carbon grains in a nonhydrogenated form. 18 refs

  20. Constraints on astronomical silicate dust

    Science.gov (United States)

    Sorrell, Wilfred H.

    1990-01-01

    Numerical radiative-transfer models are used to discuss the properties of circumstellar dust grains around the premain-sequence star AB Aur (HD 31293). It is assumed that the dust consists of a silicate-graphite mixture with Draine and Lee (1984) optical properties. The modeling technique is to match the observed FUV through FIR energy distribution with the spectral energy distribution predicted for a spherical dust shell around a luminous hot star. Special attention is given to matching the observed 10-micron silicate emission feature and the observed circumstellar absorption curve at UV wavelengths, making it possible to strengthen constraints on dust-grain opacity and chemical composition. It is concluded that, although silicate grains can explain the observed 10-micron emission feature, the Draine and Lee silicate-graphite mixture cannot explain the observed FUV circumstellar absorption at the same time. The dust shell around AB Aur contains an additional population of small particles, the most likely candidate being amorphous carbon grains in a nonhydrogenated form.

  1. Menstrual suppression for adolescents.

    Science.gov (United States)

    Altshuler, Anna Lea; Hillard, Paula J Adams

    2014-10-01

    The purpose of this review is to highlight the recent literature and emerging data describing clinical situations in which menstrual suppression may improve symptoms and quality of life for adolescents. A variety of conditions occurring frequently in adolescents and young adults, including heavy menstrual bleeding, and dysmenorrhea as well as gynecologic conditions such as endometriosis and pelvic pain, can safely be improved or alleviated with appropriate menstrual management. Recent publications have highlighted the efficacy and benefit of extended cycle or continuous combined oral contraceptives, the levonorgestrel intrauterine device, and progestin therapies for a variety of medical conditions. This review places menstrual suppression in an historical context, summarizes methods of hormonal therapy that can suppress menses, and reviews clinical conditions for which menstrual suppression may be helpful.

  2. Cryogenic Acoustic Suppression Testing

    Data.gov (United States)

    National Aeronautics and Space Administration — A proof-of-concept method utilizing a cryogenic fluid for acoustic suppression in rocket engine testing environments will be demonstrated. It is hypothesized that...

  3. Sodium fire suppression

    International Nuclear Information System (INIS)

    Malet, J.C.

    1979-01-01

    Ignition and combustion studies have provided valuable data and guidelines for sodium fire suppression research. The primary necessity is to isolate the oxidant from the fuel, rather than to attempt to cool the sodium below its ignition temperature. Work along these lines has led to the development of smothering tank systems and a dry extinguishing powder. Based on the results obtained, the implementation of these techniques is discussed with regard to sodium fire suppression in the Super-Phenix reactor. (author)

  4. How important are atmospheric depressions and nocturnal low-level jets for North African dust emission?

    Science.gov (United States)

    Fiedler, Stephanie; Schepanski, Kerstin; Knippertz, Peter; Heinold, Bernd; Tegen, Ina

    2014-05-01

    Nocturnal low-level jets (NLLJs) and atmospheric depressions are known to generate wind speeds sufficient for dust emission in North Africa, but their relative importance is not well quantified. This work presents the first climatology of dust emission associated with theses phenomenon based on ERA-Interim data from the European Centre for Medium-Range Weather Forecasts. Depressions are detected as minima in the geopotential height at 925 hPa with a tracking algorithm. NLLJs are identified with a new automated detection algorithm. The results of the identification are connected with dust emissions from a dust model driven by 10m-winds from ERA-Interim. The findings highlight that atmospheric depressions are associated with 55 % of the dust emission in the annual and spatial mean. Regions south of the Atlas Mountains in spring and wide areas of North Africa during summer have contributions of up to 90 %. Lee cyclogenesis causes favourable conditions predominantly in spring while the heat low over West Africa dominates the climatology in summer. Migrating cyclones that live for more than two days are rare and associated with 4 % of the dust emission annually and spatially averaged. Maximum contributions of cyclones to dust emission are 25 % over eastern North Africa in spring. This result suggests that few depressions forming near the Atlas Mountains undergo the development to a long-lived and moving cyclone. Even though their total contribution to dust emission is small, the emission intensity is large. The climatological mean of the emission flux is exceeded by a factor of four to eight during cyclones. The presence of soil moisture during cyclones suppresses 10 % of the dust emission. The daytime fluxes are three to five times larger than at night. NLLJs are wind speed maxima at night that build at a few 100 m above the surface. Annually and spatially averaged, NLLJs form in 29 % of nights. Single regions and seasons, e.g. the Bodélé Depression in winter and the

  5. Glass Frit Clumping And Dusting

    International Nuclear Information System (INIS)

    Steimke, J. L.

    2013-01-01

    DWPF mixes a slurry of glass frit (Frit 418) and dilute (1.5 wt%) formic acid solution with high level waste in the Slurry Mix Evaporator (SME). There would be advantages to introducing the frit in a non-slurry form to minimize water addition to the SME, however, adding completely dry frit has the potential to generate dust which could clog filters or condensers. Prior testing with another type of frit, Frit 320, and using a minimal amount of water reduced dust generation, however, the formation of hard clumps was observed. To examine options and behavior, a TTQAP [McCabe and Stone, 2013] was written to initiate tests that would address these concerns. Tests were conducted with four types of glass frit; Frit 320, DWPF Frit 418, Bekeson Frit 418 and Multi-Aspirator Frit 418. The last two frits are chemically identical to DWPF Frit 418 but smaller particles were removed by the respective vendors. Test results on Frit Clumping and Dusting are provided in this report. This report addresses the following seven questions. Short answers are provided below with more detailed answers to follow. 1. Will the addition of a small amount of water, 1.5 wt%, to dry DWPF Frit 418 greatly reduce the dust generation during handling at DWPF? a. Yes, a small scale test showed that adding a little water to the frit greatly reduced dust generation during handling. 2. Will the addition of small amounts of water to the frit cause clumping that will impair frit handling at DWPF? a. No, not with Frit 418. Although clumps were observed to form when 1.5 wt% water was mixed with DWPF Frit 418, then compressed and air-dried overnight, the clumps were easily crushed and did not form the hardened material noted when Frit 320 was tested. 3. What is the measured size distribution of dust generated when dry frit is handled? (This affects the feasibility and choice of processing equipment for removing the dust generating fraction of the frit before it is added to the SME.) a. The size distribution for

  6. Dust-mites: effect on lipid peroxidation.

    Science.gov (United States)

    Atambay, Metin; Karabulut, Aysun Bay; Aycan, Ozlem Makbule; Kilic, Eser; Yazar, Suleyman; Saraymen, Recep; Karaman, Ulku; Daldal, Nilgun

    2006-01-01

    Dust-mites are present in our homes, feed on dead exfoliated skin and other organic material. It is also known that oxidative stress may lead to cellular damage that can be confirmed by markers of cellular disruption. Oxidative stress in various infective processes has been documented. We investigated whether house dust-mites cause oxidative stress in patients. Products of lipid peroxidation in erythrocytes and lymphocytes were assessed by measuring malondialdehyde concentration. Our results showed that patients who had a positive skin test for dust-mite antigens and had dust-mites present in their houses (dust-mite positive) had increased erythrocyte malondialdehyde levels (62.39 [18.56] nmol/g-Hb) compared with those who were skin test positive, dust-mite negative (45.45 [10.82]) or skin test negative, dust-mite negative (42.20 [5.68]). They also had significantly higher levels of lymphocyte malondialdehyde (4.22 [0.55] nmol/g-protein) compared with those who were skin test positive, dust-mite negative (3.46 [0.29]) or skin test negative, dust-mite negative (1.25 [0.31]; p dust-mite negative/skin test positive and dust-mite negative/skin test negative patients. Increased malondialdehyde activity in lymphocytes and erythrocytes in the dust-mite positive/skin test positive group shows the presence of the oxidative stress in patients with dust-mite infestation.

  7. Desert Dust and Monsoon Rain

    Science.gov (United States)

    Lau, William K. M.; Kim, Kyu-Myong

    2014-01-01

    For centuries, inhabitants of the Indian subcontinent have know that heavy dust events brought on by strong winds occur frequently in the pre-monsoon season, before the onset of heavy rain. Yet scientists have never seriously considered the possibility that natural dust can affect monsoon rainfall. Up to now, most studies of the impacts of aerosols on Indian monsoon rainfall have focused on anthropogenic aerosols in the context of climate change. However, a few recent studies have show that aerosols from antropogenic and natural sources over the Indian subcontinent may affect the transition from break to active monsoon phases on short timescales of days to weeks. Writing in Nature Geoscience, Vinoj and colleagues describe how they have shown that desert dust aerosols over the Arabian Sea and West Asia can strenghten the summer monsoon over the Indial subcontinent in a matter of days.

  8. An evaluation of traditional and emerging remote sensing technologies for the detection of fugitive contamination at selected Superfund hazardous waste sites

    Science.gov (United States)

    Slonecker, E. Terrence; Fisher, Gary B.

    2011-01-01

    This report represents a remote sensing research effort conducted by the U.S. Geological Survey in cooperation with the U.S. Environmental Protection Agency (EPA) for the EPA Office of Inspector General. The objective of this investigation was to explore the efficacy of remote sensing as a technology for postclosure monitoring of hazardous waste sites as defined under the Comprehensive Environmental Response Compensation and Liability Act of 1980 (Public Law 96-510, 42 U.S.C. §9601 et seq.), also known as \\"Superfund.\\" Five delisted Superfund sites in Maryland and Virginia were imaged with a hyperspectral sensor and visited for collection of soil, water, and spectral samples and inspection of general site conditions. This report evaluates traditional and hyperspectral imagery and field spectroscopic measurement techniques in the characterization and analysis of fugitive (anthropogenic, uncontrolled) contamination at previously remediated hazardous waste disposal sites.

  9. Laboratory evaluation to reduce respirable crystalline silica dust when cutting concrete roofing tiles using a masonry saw.

    Science.gov (United States)

    Carlo, Rebecca V; Sheehy, John; Feng, H Amy; Sieber, William K

    2010-04-01

    Respirable crystalline silica dust exposure in residential roofers is a recognized hazard resulting from cutting concrete roofing tiles. Roofers cutting tiles using masonry saws can be exposed to high concentrations of respirable dust. Silica exposures remain a serious threat for nearly two million U.S. construction workers. Although it is well established that respiratory diseases associated with exposure to silica dust are preventable, they continue to occur and cause disability or death. The effectiveness of both a commercially available local exhaust ventilation (LEV) system and a water suppression system in reducing silica dust was evaluated separately. The LEV system exhausted 0.24, 0.13, or 0.12 m(3)/sec of dust laden air, while the water suppression system supplied 0.13, 0.06, 0.03, or 0.02 L/sec of water to the saw blade. Using a randomized block design, implemented under laboratory conditions, the aforementioned conditions were evaluated independently on two types of concrete roofing tiles (s-shape and flat) using the same saw and blade. Each engineering control (LEV or water suppression) was replicated eight times, or four times for each type of tile. Analysis of variance was performed by comparing the mean airborne respirable dust concentrations generated during each run and engineering control treatment. The use of water controls and ventilation controls compared with the "no control" treatment resulted in a statistically significant (p tile cut. The percent reduction for respirable dust concentrations was 99% for the water control and 91% for the LEV. Results suggest that water is an effective method for reducing crystalline silica exposures. However, water damage potential, surface discolorations, cleanup, slip hazards, and other requirements may make the use of water problematic in many situations. Concerns with implementing an LEV system to control silica dust exposures include sufficient capture velocity, additional weight of the saw with the LEV

  10. The double-dust solution

    CERN Document Server

    Krämer, Dietrich

    2002-01-01

    An exact solution describing the static gravitational field produced by the superposition of two dust beams of equal mass density but opposite propagation direction is given in a closed form. In particular, the cylindrically symmetric situation is considered in which the two dust components move on trajectories screwing around the axis. In this case, the solution can be matched to the Levi-Civita external vacuum solution at any value of the radial coordinate. The axis is regular and the mass density is positive everywhere in the interior region of the global solution. The dominant energy condition is satisfied.

  11. Intergalactic dust and quasar distribution

    International Nuclear Information System (INIS)

    Soltan, A.

    1979-01-01

    Non-homogeneous intergalactic extinction may considerably affect the quasar distribution. Especially samples of quasars isolated on the basis of B-V colours are subject to this phenomenon. Apparent grouping and close pairs of quasars reported in the literature may be a result of intergalactic dust. Using surface distribution of faint blue objects selected by Hawkins and Reddish it is estimated that intergalactic extinction in B should reach approximately 1 mag out to the redshift of approximately 1. This is slightly larger than predicted by theory and comparable to the mean dust density derived from observations. (Author)

  12. Dust Storms: Why Are Dust Storms a Concern?

    Science.gov (United States)

    ... or coccidioidomycosis. These spores live in the desert soil of semi-arid areas and are native to the ... this topic. Web Links from MedlinePlus (National Library of Medicine) Air Pollution Asthma Valley Fever More Links Dust Control On ...

  13. The global distribution of mineral dust

    International Nuclear Information System (INIS)

    Tegen, I; Schepanski, K

    2009-01-01

    Dust aerosol particles produced by wind erosion in arid and semi arid regions affect climate and air quality, but the magnitude of these effects is largely unquantified. The major dust source regions include the Sahara, the Arabian and Asian deserts; global annual dust emissions are currently estimated to range between 1000 and 3000 Mt/yr. Dust aerosol can be transported over long distances of thousands of kilometers, e.g. from source regions in the Saharan desert over the North Atlantic, or from the Asian deserts towards the Pacific Ocean. The atmospheric dust load varies considerably on different timescales. While dust aerosol distribution and dust effects are important on global scales, they strongly depend on dust emissions that are controlled on small spatial and temporal scales.

  14. The global distribution of mineral dust

    Energy Technology Data Exchange (ETDEWEB)

    Tegen, I; Schepanski, K [Leibniz Institute for Tropospheric Research, Leipzig (Germany)], E-mail: itegen@mail.tropos.de

    2009-03-01

    Dust aerosol particles produced by wind erosion in arid and semi arid regions affect climate and air quality, but the magnitude of these effects is largely unquantified. The major dust source regions include the Sahara, the Arabian and Asian deserts; global annual dust emissions are currently estimated to range between 1000 and 3000 Mt/yr. Dust aerosol can be transported over long distances of thousands of kilometers, e.g. from source regions in the Saharan desert over the North Atlantic, or from the Asian deserts towards the Pacific Ocean. The atmospheric dust load varies considerably on different timescales. While dust aerosol distribution and dust effects are important on global scales, they strongly depend on dust emissions that are controlled on small spatial and temporal scales.

  15. Infrared Observations of Cometary Dust and Nuclei

    Science.gov (United States)

    Lisse, Carey

    2004-01-01

    This bibliography lists citations for publications published under the grant. Subjects of the publications include cometary dust, instellar and interplanetary dust, comet nuclei and comae, Comet Hale-Bopp, infrared observations of comets, mass loss, and comet break-up.

  16. Electrostatic Dust Detector with Improved Sensitivity

    International Nuclear Information System (INIS)

    Boyle, D.P.; Skinner, C.H.; Roquemore, A.L.

    2008-01-01

    Methods to measure the inventory of dust particles and to remove dust if it approaches safety limits will be required in next-step tokamaks such as ITER. An electrostatic dust detector, based on a fine grid of interlocking circuit traces, biased to 30 or 50 V, has been developed for the detection of dust on remote surfaces in air and vacuum environments. Gaining operational experience of dust detection on surfaces in tokamaks is important, however the level of dust generated in contemporary short-pulse tokamaks is comparatively low and high sensitivity is necessary to measure dust on a shot-by-shot basis. We report on modifications in the detection electronics that have increased the sensitivity of the electrostatic dust detector by a factor of up to 120, - a level suitable for measurements on contemporary tokamaks.

  17. Dust emission at Franklin Lake Playa, Mojave Desert (USA): Response to meteorological and hydrologic changes 2005-2008

    Science.gov (United States)

    Reynolds, Richard L.; Bogle, Rian; Vogel, John; Goldstein, Harland L.; Yount, James

    2009-01-01

    Playa type, size, and setting; playa hydrology; and surface-sediment characteristics are important controls on the type and amount of atmospheric dust emitted from playas. Soft, evaporite-rich sediment develops on the surfaces of some Mojave Desert (USA) playas (wet playas), where the water table is shallow (areas are sources of atmospheric dust because of continuous or episodic replenishment of wind-erodible salts and disruption of the ground surface during salt formation by evaporation of ground water. Dust emission at Franklin Lake playa was monitored between March 2005 and April 2008. The dust record, based on day-time remote digital camera images captured during high wind, and compared with a nearby precipitation record, shows that aridity suppresses dust emission. High frequency of dust generation appears to be associated with relatively wet periods, identified as either heavy precipitation events or sustained regional precipitation over a few months. Several factors may act separately or in combination to account for this relation. Dust emission may respond rapidly to heavy precipitation when the dissolution of hard, wind-resistant evaporite mineral crusts is followed by the development of soft surfaces with thin, newly formed crusts that are vulnerable to wind erosion and (or) the production of loose aggregates of evaporite minerals that are quickly removed by even moderate winds. Dust loading may also increase when relatively high regional precipitation leads to decreasing depth to the water table, thereby increasing rates of vapor discharge, development of evaporite minerals, and temporary softening of playa surfaces. The seasonality of wind strength was not a major factor in dust-storm frequency at the playa. The lack of major dust emissions related to flood-derived sediment at Franklin Lake playa contrasts with some dry-lake systems elsewhere that may produce large amounts of dust from flood sediments. Flood sediments do not commonly accumulate on the

  18. Dust Measurements Onboard the Deep Space Gateway

    Science.gov (United States)

    Horanyi, M.; Kempf, S.; Malaspina, D.; Poppe, A.; Srama, R.; Sternovsky, Z.; Szalay, J.

    2018-02-01

    A dust instrument onboard the Deep Space Gateway will revolutionize our understanding of the dust environment at 1 AU, help our understanding of the evolution of the solar system, and improve dust hazard models for the safety of crewed and robotic missions.

  19. Molecules and dust in Cassiopeia A

    DEFF Research Database (Denmark)

    Biscaro, Chiara; Cherchneff, Isabelle

    2016-01-01

    We study the dust evolution in the supernova remnant Cassiopeia A. We follow the processing of dust grains that formed in the Type II-b supernova ejecta by modelling the sputtering of grains. The dust is located in dense ejecta clumps that are crossed by the reverse shock. We also investigate fur...

  20. Properties of interstellar dust in reflection nebulae

    International Nuclear Information System (INIS)

    Sellgren, K.

    1988-01-01

    Observations of interstellar dust in reflection nebulae are the closest analog in the interstellar medium to studies of cometary dust in our solar system. The presence of a bright star near the reflection nebula dust provides the opportunity to study both the reflection and emission characteristics of interstellar dust. At 0.1 to 1 micrometer, the reflection nebula emission is due to starlight scattered by dust. The albedo and scattering phase function of the dust is determined from observations of the scattered light. At 50 to 200 micrometers, thermal emission from the dust in equilibrium with the stellar radiation field is observed. The derived dust temperature determines the relative values of the absorption coefficient of the dust at wavelengths where the stellar energy is absorbed and at far infrared wavelengths where the absorbed energy is reradiated. These emission mechanisms directly relate to those seen in the near and mid infrared spectra of comets. In a reflection nebula the dust is observed at much larger distances from the star than in our solar system, so that the equilibrium dust temperature is 50 K rather than 300 K. Thus, in reflection nebulae, thermal emission from dust is emitted at 50 to 200 micrometer

  1. House dust extracts contain potent immunological adjuvants

    NARCIS (Netherlands)

    Beukelman, C.J.; Dijk, H. van; Aerts, P.C.; Rademaker, P.M.; Berrens, L.; Willers, J.M.N.

    1987-01-01

    A crude aqueous extract of house dust and two house dust subfractions were tested for adjuvant activity in a sensitivity assay performed in mice. Evidence is presented that house dust contains at least two potent immunological adjuvants. One of these, present in both subfractions, was probably

  2. Dust in the interplanetary medium

    Energy Technology Data Exchange (ETDEWEB)

    Mann, Ingrid; Lamy, Herve [Belgian Institute for Space Aeronomy, Brussels (Belgium); Czechowski, Andrzej [Space Research Center, Polish Academy of Sciences, Warsaw (Poland); Meyer-Vernet, Nicole; Zaslavsky, Arnaud, E-mail: ingrid.mann@aeronomie.b [LESIA, Observatoire de Paris, Meudon (France)

    2010-12-15

    The mass density of dust particles that form from asteroids and comets in the interplanetary medium of the solar system is, near 1 AU, comparable to the mass density of the solar wind. It is mainly contained in particles of micrometer size and larger. Dust and larger objects are destroyed by collisions and sublimation and hence feed heavy ions into the solar wind and the solar corona. Small dust particles are present in large number and as a result of their large charge to mass ratio deflected by electromagnetic forces in the solar wind. For nanodust particles of sizes {approx_equal}1-10 nm, recent calculations show trapping near the Sun and outside from about 0.15 AU ejection with velocities close to solar wind velocity. The fluxes of ejected nanodust are detected near 1 AU with the plasma wave instrument onboard the STEREO spacecraft. Although such electric signals have been observed during dust impacts before, the interpretation depends on several different parameters and data analysis is still in progress.

  3. Dust tori in radio galaxies

    NARCIS (Netherlands)

    van der Wolk, G.; Barthel, P. D.; Peletier, R. F.; Pel, J. W.

    Aims. We investigate the quasar - radio galaxy unification scenario and detect dust tori within radio galaxies of various types. Methods. Using VISIR on the VLT, we acquired sub-arcsecond (similar to 0.40 '') resolution N-band images, at a wavelength of 11.85 mu m, of the nuclei of a sample of 27

  4. Meteors, meteorites and cosmic dust

    International Nuclear Information System (INIS)

    Lebedinets, V.N.

    1987-01-01

    The problem of meteorite origin and meteorite composition is discussed. Nowadays, most scientists suppose that the giant Oort cloud consisting of ice comet nuclei is the sourse of the meteor matter. A principle unity of the matter of meteorites falling to the Earth and cosmic dust is noted as well as that of meteorite bodies evaporating in the atmosphere and bearing meteors and bodies

  5. The global transport of dust

    Science.gov (United States)

    Griffin, Dale W.; Kellogg, C.A.; Garrison, V.H.; Shinn, E.A.

    2002-01-01

    By some estimates as much as two billion metric tons of dust are lifted into the Earth's atmosphere every year. Most of this dust is stirred up by storms, the more dramatic of which are aptly named dust storms. But more than mere dirt is carried aloft. Drifting with the suspended dust particles are soil pollutants such as herbicides and pesticides and a significant number of microorganisms-bacteria, viruses and fungi. We can gain some appreciation of how much microbial life is actually floating in our atmosphere by performing a quick calculation. There are typically about one million bacteria per gram of soil, but let's be conservative and suppose there are only 10,000 bacteria per gram of airborne sediment. Assuming a modest one billion metric tons of sediment in the atmosphere, these numbers translate into a quintillion (1018) sediment-borne bacteria moving around the planet each year-enough to form a microbial bridge between Earth and Jupiter. Here we consider what we've learned about the airborne transport of sediment across the globe, and review some of the remarkable studies in this reemerging field that had it origins more than 100 years ago.

  6. Pressure suppression device

    International Nuclear Information System (INIS)

    Mizumachi, Wataru; Fukuda, Akira; Kitaguchi, Hidemi; Shimizu, Toshiaki.

    1976-01-01

    Object: To relieve and absorb impact wave vibrations caused by steam and non-condensed gases releasing into the pressure suppression chamber at the time of an accident. Structure: The reactor container is filled with inert gases. A safety valve attached main steam pipe is provided to permit the excessive steam to escape, the valve being communicated with the pressure suppression chamber through an exhaust pipe. In the pressure suppression chamber, a doughnut-like cylindrical outer wall is filled at its bottom with pool water to condense the high temperature vapor released through the exhaust pipe. A head portion of a vent tube which leads the exhaust pipe is positioned at the top, and a down comer and an exhaust vent tube are locked by means of steady rests. At the bottom is mounted a pressure adsorber device which adsorbs a pressure from the pool water. (Kamimura, M.)

  7. Models for the water-ice librational band in cool dust: possible observational test

    Science.gov (United States)

    Robinson, G.

    2014-01-01

    Of all the water-ice (H2O-ice) bands the librational band, occurring at a wavelength of about 12 μm, has proved to be the most difficult to detect observationally and also to reproduce in radiative transfer models. In fact, the case for the positive identification of the feature is strong in only a few astronomical objects. A previously suggested explanation for this is that so-called radiative transfer effects may mask the feature. In this paper, radiative transfer models are produced which unambiguously reveal the presence of the librational band as a separate resolved feature provided that there is no dust present which radiates significantly in the 10-μm region, specifically silicate-type dust. This means that the maximum dust temperature must be ≲50 K. In this case, the models indicate that the librational band may clearly be observed as an absorption feature against the stellar continuum. This suggests that the feature may be best observed by obtaining the 10-μm spectrum of stars either with very cool circumstellar dust shells, with Tmax ≲ 50 K, or those without circumstellar dust shells at all but with interstellar extinction. The first option might, however, require unrealistically large amounts of dust in the circumstellar shell in order to produce measurable absorption. Thus, the best place to look for the water-ice librational band may not be protostars with the remnants of their dust cloud still present, or evolved objects with ejected dust shells, as one might first think, because of the warm dust (Tmax ≫ 50 K) usually present in the shells of these objects. If objects associated with very cool dust exclusively do show the 3.1-μm water-ice band in deep absorption, but the librational band still does not appear, this may imply that it is not radiative transfer effects which suppress the librational band, and that some other mechanism for its suppression is in play. One possibility is that a low water-ice to silicate abundance may mask the

  8. Trapping Dust to Form Planets

    Science.gov (United States)

    Kohler, Susanna

    2017-10-01

    Growing a planet from a dust grain is hard work! A new study explores how vortices in protoplanetary disks can assist this process.When Dust Growth FailsTop: ALMA image of the protoplanetary disk of V1247 Orionis, with different emission components labeled. Bottom: Synthetic image constructed from the best-fit model. [Kraus et al. 2017]Gradual accretion onto a seed particle seems like a reasonable way to grow a planet from a grain of dust; after all, planetary embryos orbit within dusty protoplanetary disks, which provides them with plenty of fuel to accrete so they can grow. Theres a challenge to this picture, though: the radial drift problem.The radial drift problem acknowledges that, as growing dust grains orbit within the disk, the drag force on them continues to grow as well. For large enough dust grains perhaps around 1 millimeter the drag force will cause the grains orbits to decay, and the particles drift into the star before they are able to grow into planetesimals and planets.A Close-Up Look with ALMASo how do we overcome the radial drift problem in order to form planets? A commonly proposed mechanism is dust trapping, in which long-lived vortices in the disk trap the dust particles, preventing them from falling inwards. This allows the particles to persist for millions of years long enough to grow beyond the radial drift barrier.Observationally, these dust-trapping vortices should have signatures: we would expect to see, at millimeter wavelengths, specific bright, asymmetric structures where the trapping occurs in protoplanetary disks. Such disk structures have been difficult to spot with past instrumentation, but the Atacama Large Millimeter/submillimeter Array (ALMA) has made some new observations of the disk V1247 Orionis that might be just what were looking for.Schematic of the authors model for the disk of V1247 Orionis. [Kraus et al. 2017]Trapped in a Vortex?ALMAs observations of V1247 Orionis are reported by a team of scientists led by Stefan

  9. Thyroxin hormone suppression treatment

    International Nuclear Information System (INIS)

    Samuel, A.M.

    1999-01-01

    One of the important modalities of treatment of thyroid cancer (TC) after surgery is the administration of thyroxin as an adjuvant treatment. The analysis supports the theory that thyroid suppression plays an important role in patient management. 300 μg of thyroxin, as this is an adequate dose for suppression is given. Ideally the dose should be tailored by testing s-TSH levels. However, since a large number of the patients come from out station cities and villages this is impractical. We therefore depend on clinical criteria of hyperthyroid symptoms and adjust the dose. Very few patients need such adjustment

  10. Long-term EARLINET dust observations

    Science.gov (United States)

    Mona, Lucia; Amiridis, Vassilis; Amodeo, Aldo; Binietoglou, Ioannis; D'Amico, Giuseppe; Schwarz, Anja; Papagiannopoulos, Nikolaos; Papayannis, Alexandros; Sicard, Michael; Comeron, Adolfo; Pappalardo, Gelsomina

    2015-04-01

    Systematic observations of Saharan dust events over Europe are performed from May 2000 by EARLINET, the European Aerosol Research LIdar NETwork. EARLINET is a coordinated network of stations that make use of advanced lidar methods for the vertical profiling of aerosols. The backbone of EARLINET network is a common schedule for performing the measurements and the quality assurance of instruments/data. Particular attention is paid to monitoring the Saharan dust intrusions over the European continent. The geographical distribution of the EARLINET stations is particularly appealing for the dust observation, with stations located all around the Mediterranean and in the center of the Mediterranean (Italian stations) where dust intrusions are frequent, and with several stations in the central Europe where dust penetrates occasionally. All aerosol backscatter and extinction profiles related to observations collected during these alerts are grouped in the devoted "Saharan dust" category of the EARLINET database. This category consists of about 4700 files (as of December 2013). Case studies involving several stations around Europe selected from this long-term database have been provided the opportunity to investigate dust modification processes during transport over the continent. More important, the long term EARLINET dust monitoring allows the investigation of the horizontal and vertical extent of dust outbreaks over Europe and the climatological analysis of dust optical intensive and extensive properties at continental scale. This long-term database is also a unique tool for a systematic comparison with dust model outputs and satellite-derived dust products. Because of the relevance for both dust modeling and satellite retrievals improvement, results about desert dust layers extensive properties as a function of season and source regions are investigated and will be presented at the conference. First comparisons with models outputs and CALIPSO dust products will be

  11. Respiratory Toxicity of Lunar Highland Dust

    Science.gov (United States)

    James, John T.; Lam, Chiu-wing; Wallace, William T.

    2009-01-01

    Lunar dust exposures occurred during the Apollo missions while the crew was on the lunar surface and especially when microgravity conditions were attained during rendezvous in lunar orbit. Crews reported that the dust was irritating to the eyes and in some cases respiratory symptoms were elicited. NASA s vision for lunar exploration includes stays of 6 months on the lunar surface hence the health effects of periodic exposure to lunar dust need to be assessed. NASA has performed this assessment with a series of in vitro and in vivo tests on authentic lunar dust. Our approach is to "calibrate" the intrinsic toxicity of lunar dust by comparison to a nontoxic dust (TiO2) and a highly toxic dust (quartz) using intratrachael instillation of the dusts in mice. A battery of indices of toxicity is assessed at various time points after the instillations. Cultures of selected cells are exposed to test dusts to assess the adverse effects on the cells. Finally, chemical systems are used to assess the nature of the reactivity of various dusts and to determine the persistence of reactivity under various environmental conditions that are relevant to a space habitat. Similar systems are used to assess the dissolution of the dust. From these studies we will be able to set a defensible inhalation exposure standard for aged dust and predict whether we need a separate standard for reactive dust. Presently-available data suggest that aged lunar highland dust is slightly toxic, that it can adversely affect cultured cells, and that the surface reactivity induced by grinding the dust persists for a few hours after activation.

  12. Design and development of a dust dispersion chamber to quantify the dispersibility of rock dust.

    Science.gov (United States)

    Perera, Inoka E; Sapko, Michael J; Harris, Marcia L; Zlochower, Isaac A; Weiss, Eric S

    2016-01-01

    Dispersible rock dust must be applied to the surfaces of entries in underground coal mines in order to inert the coal dust entrained or made airborne during an explosion and prevent propagating explosions. 30 CFR. 75.2 states that "… [rock dust particles] when wetted and dried will not cohere to form a cake which will not be dispersed into separate particles by a light blast of air …" However, a proper definition or quantification of "light blast of air" is not provided. The National Institute for Occupational Safety and Health (NIOSH) has, consequently, designed a dust dispersion chamber to conduct quantitative laboratory-scale dispersibility experiments as a screening tool for candidate rock dusts. A reproducible pulse of air is injected into the chamber and across a shallow tray of rock dust. The dust dispersed and carried downwind is monitored. The mass loss of the dust tray and the airborne dust measurements determine the relative dispersibility of the dust with respect to a Reference rock dust. This report describes the design and the methodology to evaluate the relative dispersibility of rock dusts with and without anti-caking agents. Further, the results of this study indicate that the dispersibility of rock dusts varies with particle size, type of anti-caking agent used, and with the untapped bulk density. Untreated rock dusts, when wetted and dried forming a cake that was much less dispersible than the reference rock dust used in supporting the 80% total incombustible content rule.

  13. Lunar dust - Implications for astronomical observatories

    Science.gov (United States)

    Johnson, Stewart W.; Chua, Koon M.; Burns, Jack O.; Slane, Frederic A.

    1991-01-01

    The properties, origins, and previous operational experiences with lunar dust are discussed, with emphasis on the implications for world-class astronomy on the moon. The mechanisms that may govern the behavior of the fine particles are suggested, and working hypotheses for mitigating the dust hazard are advanced. Future experiments, both on the moon and in terrestrial simulations, that will assist in establishing effective and suitable means of limiting deleterious effects of dust on observatory operations are outlined. Dust studies of components returned by Surveyor 3 are presented. The performance of laser retroreflectors under conditions of moon dust is discussed.

  14. [Allergenic mites (Acariformes, Pyroglyphidae) in house dust].

    Science.gov (United States)

    Zhëltikova, T M; Petrova-Nikitina, A D; Kanchurin, A Kh; Berzhets, V M; Muzylëva, I L

    1987-01-01

    Paper is the second part of the literature review on house dust mites (including 1985). It deals with the diagnosis of the dust mite allergy, the nature of the mite allergens, distribution and population density of the mites in various premises, seasonal population dynamics and population age structure of the dermatophagoid mites, life cycle and breeding of Dermatophagoides pteronyssinus and D. farinae on different food substrates. The methods of the house dust mite control are discussed. The original data on the house dust mite distribution in Moscow is shown. A comparative estimation of the results of mite antigens in the house dust discovering by the acarological and three immunological methods are given.

  15. Dust bands in the asteroid belt

    International Nuclear Information System (INIS)

    Sykes, M.V.; Greenberg, R.; Dermott, S.F.; Nicholson, P.D.; Burns, J.A.

    1989-01-01

    This paper describes the original IRAS observations leading to the discovery of the three dust bands in the asteroid belt and the analysis of data. Special attention is given to an analytical model of the dust band torus and to theories concerning the origin of the dust bands, with special attention given to the collisional equilibrium (asteroid family), the nonequilibrium (random collision), and the comet hypotheses of dust-band origin. It is noted that neither the equilibrium nor nonequilibrium models, as currently formulated, present a complete picture of the IRAS dust-band observations. 32 refs

  16. Numerical Prediction of Dust. Chapter 10

    Science.gov (United States)

    Benedetti, Angela; Baldasano, J. M.; Basart, S.; Benincasa, F.; Boucher, O.; Brooks, M.; Chen, J. P.; Colarco, P. R.; Gong, S.; Huneeus, N.; hide

    2013-01-01

    Covers the whole breadth of mineral dust research, from a scientific perspective Presents interdisciplinary work including results from field campaigns, satellite observations, laboratory studies, computer modelling and theoretical studies Explores the role of dust as a player and recorder of environmental change This volume presents state-of-the-art research about mineral dust, including results from field campaigns, satellite observations, laboratory studies, computer modelling and theoretical studies. Dust research is a new, dynamic and fast-growing area of science and due to its multiple roles in the Earth system, dust has become a fascinating topic for many scientific disciplines. Aspects of dust research covered in this book reach from timescales of minutes (as with dust devils, cloud processes, and radiation) to millennia (as with loess formation and oceanic sediments), making dust both a player and recorder of environmental change. The book is structured in four main parts that explore characteristics of dust, the global dust cycle, impacts of dust on the Earth system, and dust as a climate indicator. The chapters in these parts provide a comprehensive, detailed overview of this highly interdisciplinary subject. The contributions presented here cover dust from source to sink and describe all the processes dust particles undergo while travelling through the atmosphere. Chapters explore how dust is lifted and transported, how it affects radiation, clouds, regional circulations, precipitation and chemical processes in the atmosphere, and how it deteriorates air quality. The book explores how dust is removed from the atmosphere by gravitational settling, turbulence or precipitation, how iron contained in dust fertilizes terrestrial and marine ecosystems, and about the role that dust plays in human health. We learn how dust is observed, simulated using computer models and forecast. The book also details the role of dust deposits for climate reconstructions

  17. Model Dust Envelopes Around Silicate Carbon Stars

    Directory of Open Access Journals (Sweden)

    Kyung-Won Suh

    2006-03-01

    Full Text Available We have modeled dust envelopes around silicate carbon stars using optical properties for a mixture of amorphous carbon and silicate dust grains paying close attention to the infrared observations of the stars. The 4 stars show various properties in chemistry and location of the dust shell. We expect that the objects that fit a simple detached silicate dust shell model could be in the transition phase of the stellar chemistry. For binary system objects, we find that a mixed dust chemistry model would be necessary.

  18. Response of the Water Cycle of West Africa and Atlantic to Radiative Forcing by Saharan Dust

    Science.gov (United States)

    Lau, K. M.; Kim, Kyu-Myong; Sud, Yogesh C.; Walker, Gregory L.

    2010-01-01

    The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence in support of the "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summer, as a result of large-scale atmospheric feed back triggered by absorbing dust aerosols, rainfall and cloudiness are enhanced over the West Africa/Easter Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean. region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while long wave has the opposite response. The elevated dust layer warms the air over Nest Africa and the eastern Atlantic. The condensation heating associated with the induced deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in northward shift of the West Africa precipitation over land, increased low-level westerlies flow over West Africa at the southern edge of the dust layer, and a near surface energy fluxes, resulting in cooling of the Nest African land and the eastern Atlantic, and a warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at 0.95 or higher.

  19. No evidence for dust B -mode decorrelation in Planck data

    Science.gov (United States)

    Sheehy, Christopher; Slosar, Anže

    2018-02-01

    Constraints on inflationary B modes using cosmic microwave background polarization data commonly rely on either template cleaning or cross-spectra between maps at different frequencies to disentangle Galactic foregrounds from the cosmological signal. Assumptions about how the foregrounds scale with frequency are therefore crucial to interpreting the data. Recent results from the Planck satellite collaboration claim significant evidence for a decorrelation in the polarization signal of the spatial pattern of Galactic dust between 217 and 353 GHz. Such a decorrelation would suppress power in the cross-spectrum between high-frequency maps, where the dust is strong, and lower-frequency maps, where the sensitivity to cosmological B modes is strongest. Alternatively, it would leave residuals in lower-frequency maps cleaned with a template derived from the higher-frequency maps. If not accounted for, both situations would result in an underestimate of the dust contribution and thus an upward bias on measurements of the tensor-to-scalar ratio, r . In this paper, we revisit this measurement and find that the no-decorrelation hypothesis cannot be excluded with the Planck data. There are three main reasons for this: (i) There is significant noise bias in cross-spectra between Planck data splits that needs to be accounted for. (ii) There is strong evidence for unknown instrumental systematics, the amplitude of which we estimate using alternative Planck data splits. (iii) There are significant correlations between measurements in different sky patches that need to be taken into account when assessing the statistical significance. Between ℓ=55 - 90 and over 72% of the sky, the dust B B correlation between 217 and 353 GHz is 1.001-.004/.000 +.004 /.021 (68 % stat /syst .) and shows no significant trend with the sky fraction.

  20. Enhanced Saharan dust input to the Levant during Heinrich stadials

    Science.gov (United States)

    Torfstein, Adi; Goldstein, Steven L.; Stein, Mordechai

    2018-04-01

    The history of dust transport to the Levant during the last glacial period is reconstructed using the isotope ratios of Pb, Sr, Nd, and Hf in sediments of Lake Lisan, the last glacial Dead Sea. Exposed marginal sections of the Lisan Formation were sampled near Masada, the Perazim Valley and from a core drilled at the deep floor of the modern lake. Bulk samples and size fractions display unique isotopic fingerprints: the finest detritus fraction (<5 μm) displays higher 87Sr/86Sr and lower εNd values (0.710-0.713 and -7.0 to -9.8, respectively) relative to the coarser fractions (5-20 μm and <20 μm; 0.708-0.710 and -3.4 to -8.3) and the bulk detritus samples (0.709-0.711 and -6 to -7.5). Similarly, the 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios (18.26-19.02, 15.634-15.68, and 38.25-38.82, respectively) are systematically higher in the finest detritus fraction relative to corresponding coarser fractions and bulk samples. The 87Sr/86Sr and εNd values of the finest fraction correspond with those of atmospheric dust originating from the Sahara Desert, while those of the coarse fractions are similar to loess deposits exposed in the Sinai and Negev Deserts. Pronounced excursions in the Sr-Nd-Pb isotope ratios toward more Sahara-like values coincide with the Heinrich (H) stadials 6, 5 and 1, reflecting significant increases in Saharan dust fluxes during regionally arid intervals, reflected by sharp lake level drops. Moreover, during H6 the dust came from different Saharan sources than during H1 and H5. While the relatively wet glacial climate in the Levant suppressed the transport of dust to the lake watershed, short-term hyper-arid spells during H-stadial intervals were accompanied by enhanced supply of fine Sahara dust to this region.

  1. Plasma suppression of beamstrahlung

    International Nuclear Information System (INIS)

    Whittum, D.H.; Sessler, A.M.; Stewart, J.J.; Yu, S.S.

    1988-06-01

    We investigate the use of a plasma at the interaction point of two colliding beams to suppress beamsstrahlung and related phenomena. We derive conditions for good current cancellation via plasma return currents and report on numerical simulations conducted to confirm our analytic results. 10 refs., 5 figs., 4 tabs

  2. Industrial robot having dust-proof structure

    Energy Technology Data Exchange (ETDEWEB)

    Torii, N.; Ito, S.; Wakio, H.; Iwasaki, K

    1989-06-06

    This patent describes an industrial robot having a dust-proof structure comprising: at least one dust cover having an opening; a linearly moving unit extending through the opening of the dust cover and moved back and forth in the longitudinal direction thereof; a suction unit for exerting suction on an interior of the dust cover to cause an air stream to flow from outside the dust cover into the dust cover through the opening; and a ring member disposed at the opening of the dust cover in such a manner as to encompass the outer periphery of the linearly moving unit through a gap, the ring member being formed at the inner peripheral surface thereof with at least one annular groove for reserving air, encompassing the outer periphery of the linearly moving unit.

  3. [Determination of house dust mites in Eskisehir].

    Science.gov (United States)

    Doğan, Nihal; Aycan, Ozlem Makbule; Miman, Ozlem; Atambay, Metin; Daldal, Nilgün

    2008-01-01

    House dust contains various organic and inorganic materials. The most important parts of the house dust are dust mites causing allergic diseases such as allergic rhinitis, asthma, atopic dermatitis and seasonal keratoconjunctivitis. In this study, a total of 72 random house dust samples collected from various regions of Eskisehir were examined. The dust samples were examined by the lactic acid precipitation method which was modified from the Spieksma-Boezaman's method. The mite positive house dust rate was 16.67% including Dermatophagoides pteronyssinus, Chortoglyphus arcuatus and Tyrophagus sp. It was concluded that investigation of a greater number of samples would lead to more precise rate of detection of mite positive dust and also that more mite species would be found.

  4. Contribution of dust transport and resuspension to particulate matter levels in the Mediterranean atmosphere

    Science.gov (United States)

    Đorđević, Dragana; Vukmirović, Zorka; Tošić, Ivana; Unkašević, Miroslava

    A sampling site at Herceg-Novi (Montenegro) is included in the network for the monitoring of airborne pollutants along the Mediterranean coast. The 24-h concentrations of total suspended particles (TSP) were measured by a standardized gravimetric method in a 1-in-6 day schedule program. The available data set from the period 1995-2000 was chosen for statistical analysis. The 3-parameter Weibull probability model successfully described the distributions of TSP concentrations as the total population and the part of them transported from the continental side. However, in the concentration set from the southern segment, outliers were found indicating the appearance of the highest concentrations from the open Adriatic Sea. The collected particles mostly constituted of PM10 and the ratio PM10/TSP reached value of 0.9. An analysis of the filter samples by scanning electron microscopy (SEM) confirmed the presence of marine aerosol, crustal and amorphous material. The Fe content of >2% in the TSP samples was accepted for the identification of genuine Saharan dust transport. The frequency of these events of 7% a year contributed to an increase of the annual TSP concentrations of 10%-15%. The amorphous material was found in the sample of 31 May/1 June 1999 after the bombing of Cape Arza on the Luštica Peninsula, which is situated 5 km away from the sampling site. The attack occurred on 30 May and depleted uranium ammunition was used. The 238U radioactivity was at the background level, but the pulverous material found in that sample most likely originated from dust and soil transported from Cape Arza to Herceg-Novi on 31 May as the backward trajectory analysis by the Eta model showed. Resuspension was the dominant process affecting the TSP concentration, but this episode did not reflect significantly on the annual TSP levels, as is the case with the Saharan dust storms. The methodology applied in this work allowed a fugitive source of PM from destroyed objects and bombed

  5. Coupling Mars' Dust and Water Cycles: Effects on Dust Lifting Vigor, Spatial Extent and Seasonality

    Science.gov (United States)

    Kahre, M. A.; Hollingsworth, J. L.; Haberle, R. M.; Montmessin, F.

    2012-01-01

    The dust cycle is an important component of Mars' current climate system. Airborne dust affects the radiative balance of the atmosphere, thus greatly influencing the thermal and dynamical state of the atmosphere. Dust raising events on Mars occur at spatial scales ranging from meters to planet-wide. Although the occurrence and season of large regional and global dust storms are highly variable from one year to the next, there are many features of the dust cycle that occur year after year. Generally, a low-level dust haze is maintained during northern spring and summer, while elevated levels of atmospheric dust occur during northern autumn and winter. During years without global-scale dust storms, two peaks in total dust loading were observed by MGS/TES: one peak occurred before northern winter solstice at Ls 200-240, and one peak occurred after northern winter solstice at L(sub s) 305-340. These maxima in dust loading are thought to be associated with transient eddy activity in the northern hemisphere, which has been observed to maximize pre- and post-solstice. Interactive dust cycle studies with Mars General Circulation Models (MGCMs) have included the lifting, transport, and sedimentation of radiatively active dust. Although the predicted global dust loadings from these simulations capture some aspects of the observed dust cycle, there are marked differences between the simulated and observed dust cycles. Most notably, the maximum dust loading is robustly predicted by models to occur near northern winter solstice and is due to dust lifting associated with down slope flows on the flanks of the Hellas basin. Thus far, models have had difficulty simulating the observed pre- and post- solstice peaks in dust loading. Interactive dust cycle studies typically have not included the formation of water ice clouds or their radiative effects. Water ice clouds can influence the dust cycle by scavenging dust from atmosphere and by interacting with solar and infrared radiation

  6. Dunes and Dust Devil Tracks

    Science.gov (United States)

    2004-01-01

    22 August 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of dark sand dunes that formed in winds blowing from east (right) to west (left), along with smaller, lighter-toned ripples and many dark dust devil tracks. The dust devil tracks indicate movement from a variety of directions, while the dunes only indicate winds from the east. In the lower left quarter of the image, dune sand has flowed around a layered rock obstacle. This scene is located near 19.9oN, 280.5oW. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the lower left.

  7. Polyfluoroalkyl chemicals in house dust

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Kayoko [Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Hwy., Mailstop F53, Atlanta, GA 30341 (United States); Calafat, Antonia M., E-mail: acalafat@cdc.gov [Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Hwy., Mailstop F53, Atlanta, GA 30341 (United States); Needham, Larry L. [Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Hwy., Mailstop F53, Atlanta, GA 30341 (United States)

    2009-07-15

    We developed a high throughput analytical method using on-line solid phase extraction coupled with isotope dilution high-performance liquid chromatography-tandem mass spectrometry (on-line SPE-HPLC-MS/MS) to simultaneously determine the concentrations of 17 polyfluoroalkyl chemicals (PFCs) in house dust. The sample preparation includes dispersion of the dust samples in 0.1 M formic acid:MeOH (1:1), followed by agitation and filtration, addition of the isotope-labeled internal standard solution to the filtrate, and analysis by on-line SPE-HPLC-MS/MS. The limits of quantitation were <4.0 ng/g. The method accuracies ranged between 73.2% and 100.2% for the different analytes at two spike levels. We confirmed the validity of the method by analyzing 39 household dust samples collected in 2004. Of the 17 PFCs measured, 6 of them-perfluorobutane sulfonate (PFBuS), N-ethyl-perfluorooctane sulfonamide, 2-(N-ethyl-perfluorooctane sulfonamido) acetic acid (Et-PFOSA-AcOH), 2-(N-methyl-perfluorooctane sulfonamido) ethanol (Me-PFOSA-EtOH), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS)-had detection frequencies >70%. We detected PFOS, PFBuS, and PFHxS at the highest median concentration, followed by Et-PFOSA-AcOH and Me-PFOSA-EtOH.

  8. Respiratory effects of borax dust.

    Science.gov (United States)

    Garabrant, D H; Bernstein, L; Peters, J M; Smith, T J; Wright, W E

    1985-12-01

    The relation of respiratory symptoms, pulmonary function, and abnormalities of chest radiographs to estimated exposures of borax dust has been investigated in a cross sectional study of 629 actively employed borax workers. Ninety three per cent of the eligible workers participated in the study and exposures ranged from 1.1 mg/m3 to 14.6 mg/m3. Symptoms of acute respiratory irritation such as dryness of the mouth, nose, or throat, dry cough, nose bleeds, sore throat, productive cough, shortness of breath, and chest tightness were related to exposures of 4.0 mg/m3 or more, and were infrequent at exposures of 1.1 mg/m3. Symptoms of persistent respiratory irritation meeting the definition of chronic simple bronchitis were related to exposure among non-smokers. Decrements in the FEV1 as a percentage of predicted were seen among smokers who had heavy cumulative borax exposures (greater than or equal to 80 mg/m3 years) but were not seen among less exposed smokers or among non-smokers. Radiographic abnormalities were uncommon and were not related to dust exposure. Borax dust appears to act as a simple respiratory irritant and perhaps causes small changes in the FEV1 among smokers who are heavily exposed.

  9. Dust-Tolerant Intelligent Electrical Connection System

    Science.gov (United States)

    Lewis, Mark; Dokos, Adam; Perotti, Jose; Calle, Carlos; Mueller, Robert; Bastin, Gary; Carlson, Jeffrey; Townsend, Ivan, III; Immer, Chirstopher; Medelius, Pedro

    2012-01-01

    Faults in wiring systems are a serious concern for the aerospace and aeronautic (commercial, military, and civilian) industries. Circuit failures and vehicle accidents have occurred and have been attributed to faulty wiring created by open and/or short circuits. Often, such circuit failures occur due to vibration during vehicle launch or operation. Therefore, developing non-intrusive fault-tolerant techniques is necessary to detect circuit faults and automatically route signals through alternate recovery paths while the vehicle or lunar surface systems equipment is in operation. Electrical connector concepts combining dust mitigation strategies and cable diagnostic technologies have significant application for lunar and Martian surface systems, as well as for dusty terrestrial applications. The dust-tolerant intelligent electrical connection system has several novel concepts and unique features. It combines intelligent cable diagnostics (health monitoring) and automatic circuit routing capabilities into a dust-tolerant electrical umbilical. It retrofits a clamshell protective dust cover to an existing connector for reduced gravity operation, and features a universal connector housing with three styles of dust protection: inverted cap, rotating cap, and clamshell. It uses a self-healing membrane as a dust barrier for electrical connectors where required, while also combining lotus leaf technology for applications where a dust-resistant coating providing low surface tension is needed to mitigate Van der Waals forces, thereby disallowing dust particle adhesion to connector surfaces. It also permits using a ruggedized iris mechanism with an embedded electrodynamic dust shield as a dust barrier for electrical connectors where required.

  10. House dust mites, our intimate associates.

    Science.gov (United States)

    Nadchatram, M

    2005-06-01

    House dust mites have lived in human contact from time immemorial. Human dander or dead skin constitutes the major organic component of the house dust ecosystem. Because the mites feed on dander, dust mites and human association will continue to co-exist as part of our environment. Efficient house-keeping practice is the best form of control to reduce infestation. However, special precautions are important when individuals are susceptible or sensitive to dust mites. House dust mites are responsible for causing asthma, rhinitis and contact dermatitis. The respiratory allergies are caused by the inhalation of dead or live mites, their faecal matter or other byproducts. Immune factors are of paramount importance in the development of dust related or mite induced respiratory diseases. House dust mites were found in some 1,000 samples of dust taken from approximately 330 dwellings in Peninsular Malaysia and Singapore. Mattresses, carpets, corners of a bedroom, and floor beneath the bed are favourable dust mite habitats. The incriminating species based on studies here and elsewhere, as well as many other species of dust mites of unknown etiological importance are widely distributed in Malaysian homes. Density of dust mites in Malaysia and Singapore is greater than in temperate countries. Prevention and control measures with reference to subjects sensitive to dust mite allergies, including chemical control described in studies conducted in Europe and America are discussed. However, a cost free and most practical way to remove mites, their faecal matter and other products is to resort to sunning the bedding and carpets to kill the living mites, and then beaten and brushed to remove the dust and other components.

  11. J/Ψ suppression

    International Nuclear Information System (INIS)

    Giubellino, P.; Abreu, M.C.; Alessandro, B.; Alexa, C.; Arnaldi, R.; Astruc, J.; Atayan, M.; Baglin, C.; Baldit, A.; Bedjidian, M.; Bellaiche, F.; Beole, S.; Boldea, V.; Bordalo, P.; Bussiere, A.; Capony, V.; Casagrande, L.; Castor, J.; Chambon, T.; Chaurand, B.; Chevrot, I.; Cheynis, B.; Chiavassa, E.; Cicalo, C.; Comets, M.P.; Constantinescu, S.; Cruz, J.; De Falco, A.; De Marco, N.; Dellacasa, G.; Devaux, A.; Dita, S.; Drapier, O.; Espagnon, B.; Fargeix, J.; Filippov, S.N.; Fleuret, F.; Force, P.; Gallio, M.; Gavrilov, Y.K.; Gerschel, C.; Giubellino, P.; Golubeva, M.B.; Gonin, M.; Grigorian, A.A.; Grossiord, J.Y.; Guber, F.F.; Guichard, A.; Gulkaninan, H.; Hakobyan, R.; Haroutunian, R.; Idzik, M.; Jouan, D.; Karavitcheva, T.L.; Kluberg, L.; Kurepin, A.B.; Le Bornec, Y.; Lourenco, C.; Mac Cormick, M.; Macciotta, P.; Marzari-Chiesa, A.; Masera, M.; Masoni, A.; Mehrabyan, S.; Mourgues, S.; Musso, A.; Ohlsson-Malek, F.; Petiau, P.; Piccotti, A.; Pizzi, J.R.; Prado da Silva, W.L.; Puddu, G.; Quintans, C.; Racca, C.; Ramello, L.; Ramos, S.; Rato-Mendes, P.; Riccati, L.; Romana, A.; Sartori, S.; Saturnini, P.; Scomparin, E.; Serci, S.; Shahoyan, R.; Silva, S.; Soave, C.; Sonderegger, P.; Tarrago, X.; Temnikov, P.; Topilskaya, N.S.; Usai, G.; Vale, C.; Vercellin, E.; Willis, N.

    1999-01-01

    The cross section for J/Ψ production in Pb-Pb interactions at 158 GeV per nucleon is measured at the CERN SPS by the NA50 experiment. The final results from the 1995 run are presented here together with preliminary ones from the high-statistics 1996 run. An anomalous J/Ψ suppression is observed in Pb-Pb collisions as compared to extrapolations of the previous results obtained by the NA38 experiment with proton and lighter ion beams. The results of the two runs are in good agreement. The results from the 1996 run allow the study of the onset of the anomalous suppression within the same set of data, showing evidence of a sharp change of behaviour around a value of neutral transverse energy, as measured by our electromagnetic calorimeter, of about 50 GeV

  12. A Fractal Model for the Capacitance of Lunar Dust and Lunar Dust Aggregates

    Science.gov (United States)

    Collier, Michael R.; Stubbs, Timothy J.; Keller, John W.; Farrell, William M.; Marshall, John; Richard, Denis Thomas

    2011-01-01

    Lunar dust grains and dust aggregates exhibit clumping, with an uneven mass distribution, as well as features that span many spatial scales. It has been observed that these aggregates display an almost fractal repetition of geometry with scale. Furthermore, lunar dust grains typically have sharp protrusions and jagged features that result from the lack of aeolian weathering (as opposed to space weathering) on the Moon. A perfectly spherical geometry, frequently used as a model for lunar dust grains, has none of these characteristics (although a sphere may be a reasonable proxy for the very smallest grains and some glasses). We present a fractal model for a lunar dust grain or aggregate of grains that reproduces (1) the irregular clumpy nature of lunar dust, (2) the presence of sharp points, and (3) dust features that span multiple scale lengths. We calculate the capacitance of the fractal lunar dust analytically assuming fixed dust mass (i.e. volume) for an arbitrary number of fractal levels and compare the capacitance to that of a non-fractal object with the same volume, surface area, and characteristic width. The fractal capacitance is larger than that of the equivalent non-fractal object suggesting that for a given potential, electrostatic forces on lunar dust grains and aggregates are greater than one might infer from assuming dust grains are sphericaL Consequently, electrostatic transport of lunar dust grains, for example lofting, appears more plausible than might be inferred by calculations based on less realistic assumptions about dust shape and associated capacitance.

  13. House dust in seven Danish offices

    Science.gov (United States)

    Mølhave, L.; Schneider, T.; Kjærgaard, S. K.; Larsen, L.; Norn, S.; Jørgensen, O.

    Floor dust from Danish offices was collected and analyzed. The dust was to be used in an exposure experiment. The dust was analyzed to show the composition of the dust which can be a source of airborne dust indoors. About 11 kg of dust from vacuum cleaner bags from seven Danish office buildings with about 1047 occupants (12 751 m 2) was processed according to a standardized procedure yielding 5.5 kg of processed bulk dust. The bulk dust contained 130.000-160.000 CFU g -1 microorganisms and 71.000-90.000 CFU g -1 microfungi. The content of culturable microfungi was 65-123 CFU 30 g -1 dust. The content of endotoxins ranged from 5.06-7.24 EU g -1 (1.45 ng g -1 to 1.01 ng g -1). Allergens (ng g -1) were from 147-159 (Mite), 395-746 (dog) and 103-330 (cat). The macro molecular organic compounds (the MOD-content) varied from 7.8-9.8 mg g -1. The threshold of release of histamine from basophil leukocytes provoked by the bulk dust was between 0.3 and 1.0 mg ml -1. The water content was 2% (WGT) and the organic fraction 33%. 6.5-5.9% (dry) was water soluble. The fiber content was less than 0.2-1.5% (WGT) and the desorbable VOCs was 176-319 μg g -1. Most of the VOC were aldehydes. However, softeners for plastic (DBP and DEHP) were present. The chemical composition includes human and animal skin fragments, paper fibers, glass wool, wood and textilefibers and inorganic and metal particles. The sizes ranged from 0.001-1 mm and the average specific density was 1.0 g m -3. The bulk dust was resuspended and injected into an exposure chamber. The airborne dust was sampled and analyzed to illustrate the exposures that can result from sedimented dirt and dust. The airborne dust resulting from the bulk dust reached concentrations ranging from 0.26-0.75 mg m -3 in average contained 300-170 CFU m -3. The organic fraction was from 55-70% and the water content about 2.5% (WGT). The content of the dust was compared to the similar results reported in the literature and its toxic potency is

  14. Analysis of influence factors on dust removal efficiency for novel photovoltaic lunar dust removal technology

    Science.gov (United States)

    Jiang, Jing; Zhao, Hongyue; Wang, Lei; Yue, Honghao; Hou, Xuyan

    2017-12-01

    The deposition of lunar dust on the surface of a lunar probe has an adverse effect on the performance of the equipment. This paper proposes novel lunar dust removal technology, which is triggered by UV light isolated from sunlight, to clean the adhered dust using the high voltage produced by the anomalous photovoltaic effect of lanthanum modified lead zirconate titanate. Based on the equivalent electrical model, the mathematical model of electrostatic field force used for removing lunar dust particles is established. Based on the mathematical model the influencing factors of dust removal efficiency are proposed and analyzed by experiments. To improve the dust removal efficiency, a conductive dust removal electrode is designed, coated with a layer of insulating film to avoid the reciprocating motion of dust particles, and the feasibility of the configuration is proved by experiments.

  15. Trace metals in urban road dust

    International Nuclear Information System (INIS)

    Randazzo, Loredana Antonella; Dongarra, Gaetano; Manno, Emanuela; Varrica, Daniela

    2006-01-01

    Heavy metals associated with urban road dust is a matter for concern as they may have serious effects on biological systems. The bioavailability and potential toxicity of metals bound to urban dust is related to the specific chemical form of the element. In the present article are reported the determinations and chemical speciation of As, Ba, Cr, Cu, Mo, Ni, Pb and Zn in six samples of road dust collected within the urban centre and the outskirts of Palermo [it

  16. Electrostatic Dust Control on Planetary Surfaces

    Science.gov (United States)

    Clark, P. E.; Calle, C. I.; Curtis, S. A.; Keller, J. F.; Minetto, F.; Mantovani, J. G.

    2007-01-01

    Successful operation for exploration of planetary regoliths will depend on the capability to keep surfaces free of dust which could compromise performance and to collect dust for characterization. Such study is essential in order to resolve issues in dealing with regolith fines identified during the Apollo missions where dust behaved like abrasive Velcro before returning to the Moon. During Moon landings, locally-induced stirring of the regolith caused dust to be suspended long enough to come into contact with conducting surfaces. Lunar fines, because of their electrostatic charging, were difficult to collect and sparsely sampled: bag seals were broken, samples contaminated and lost. Our objectives here are to describe a multi-faceted electrostatically-based approach and methodology for addressing this issue, as well as to present our preliminary results which confirm the view that the successful strategy will deal with dust dynamics resulting from interaction between mechanical and electrostatic forces. Our device concept combines electron or ion beams, acting as a plasma dust sweeper to control the flow of dust by systematic scanning of the surface with an electrostatically controlled potential. A plate of the opposite potential used to induce dust migration in the presence of an electrical field. Our goal is a compact device of dust for sampling as part of the extended exploration process on extensive areas of exposed impact-generated regolith, on Mercury, Mars, asteroids or outer solar system satellites, as well as the Moon.

  17. Dust control at Yucca Mountain project

    International Nuclear Information System (INIS)

    Kissell, F.; Jurani, R.; Dresel, R.; Reaux, C.

    1999-01-01

    This report describes actions taken to control silica dust at the Yucca Mountain Exploratory Studies Facility, a tunnel located in Southern Nevada that is part of a scientific program to determine site suitability for a potential nuclear waste repository. The rock is a volcanic tuff containing significant percentages of both quartz and cristobalite. Water use for dust control was limited because of scientific test requirements, and this limitation made dust control a difficult task. Results are reported for two drifts, called the Main Loop Drift and the Cross Drift. In the Main Loop Drift, dust surveys and tracer gas tests indicated that air leakage from the TBM head, the primary ventilation duct, and movement of the conveyor belt were all significant sources of dust. Conventional dust control approaches yielded no significant reductions in dust levels. A novel alternative was to install an air cleaning station on a rear deck of the TBM trailing gear. It filtered dust from the contaminated intake air and discharged clean air towards the front of the TBM. The practical effect was to produce dust levels below the exposure limit for all TBM locations except close to the head. In the Cross Drift, better ventilation and an extra set of dust seals on the TBM served to cut down the leakage of dust from the TBM cutter head. However, the conveyor belt was much dustier than the belt in the main loop drift. The problem originated with dirt on the bottom of the belt return side and much spillage from the belt top side. Achieving lower dust levels in hard rock tunneling operations will require new approaches as well as a more meticulous application of existing technology. Planning for dust control will require specific means to deal with dust that leaks from the TBM head, dust that originates with leaky ventilation systems, and dust that comes from conveyor belts. Also, the application of water could be more efficient if automatic controls were used to adjust the water flow

  18. Migration, Masculinity and the Fugitive State of Mind in the Irish Emigrant Footballer Autobiography: the Case of Paul McGrath

    Directory of Open Access Journals (Sweden)

    Marcus Free

    2010-03-01

    Full Text Available The ‘confessional’ autobiography has become a popular variant of professional football autobiography in Britain. Co-written ‘autobiographies’ by prominent former emigrant Irish or Irish descended international footballers have featured prominently in this sub-genre.  Their ‘confessions’ of alcoholism, gambling, infidelity, irresponsibility towards partners or dependents, or underlying ontological insecurity might be seen as an insightful engagement with their lives as male footballers in Britain.  However, focusing on two autobiographies of Paul McGrath, and reading these ‘troubled’ accounts using psychoanalytic perspectives on sport, migration and masculinity, it is argued that they are contradictory texts which embody a peculiar variation on the emigrant “fugitive state of mind” (Davar, 1996, both approximating and deferring mature, reflexive engagement with the social and cultural construction of identity, allowing them to occupy a liminal but discontent imaginary space in which adolescent masculinity can be indefinitely extended.   The homosocial world of men’s professional football is a key factor in this.

  19. Dust explosion hazard in ITER: Explosion indices of fine graphite and tungsten dusts and their mixtures

    International Nuclear Information System (INIS)

    Denkevits, A.; Dorofeev, S.

    2005-01-01

    Addressing the dust explosion hazard in ITER, a standard method with a 20-l-spherical combustion chamber was used to measure the explosion indices of fine graphite and tungsten dusts and their mixtures. The indices include maximum overpressure, maximum rate of pressure rise, and lower explosion concentration limit. The effect of dust particle size was studied on the explosion behaviour of graphite dusts in the range 4-45 μm. The explosion indices of 1 μm tungsten dust and its mixtures with 4 μm graphite dust were measured. The graphite dust particle size is shown to have a profound effect on the explosion characteristics. The finest dust features the highest maximum overpressure and rate of pressure rise, and the lowest explosible concentration. Four tungsten/graphite dust mixtures with molar ratios of W/C = 1/30, 1/4, 1/1, and 3/1 were tested at the concentrations at which the dust combustion consumed all the oxygen in air producing maximum overpressures and rates of pressure rise. The maximum overpressure decreases slightly with increasing tungsten content, while the maximum rate of pressure rise has a pronounced peak at W/C=1/1, i.e. this mixture burns faster than both pure graphite and pure tungsten dusts alone. All the tested dusts belong to the mildest explosion class

  20. Dust acoustic shock wave generation due to dust charge variation in ...

    Indian Academy of Sciences (India)

    Burger equation. Results of the numerical investigation of the propagation of large-amplitude dust acoustic stationary shock wave are presented here using the complete set of non-linear dust fluid equations coupled with the dust charging equation and Poisson equation. The DA waves are of compressional type showing ...

  1. THE MAIN CULPRIT IN ALLERGIC RHINITIS - HOUSE DUST OR HOUSE DUST MITE

    Directory of Open Access Journals (Sweden)

    Abhey

    2015-10-01

    Full Text Available Allergic rhinitis especially perennial type makes life miserable for the patient. House dust mite is one of the major players causing it. This study is to compare the allergen i n city of house dust mite versus house dust and evaluate any cross - allergenicity between them. STUDY DESIGN: Prospective study in a tertiary referral hospital. MATERIALS & METHODS: Forty patients of allergic rhinitis and well matched controls were subjected to intradermal skin tests to house dust and house dust mite allergen. The skin tests were graded as per standard norms and the responses matched after correlating with different parameters. Statistical analysis was done and the results evaluated. RESULTS: House dust mite was the main allergen, as compared to house dust, responsible for causing allergic rhinitis. The allergen reactivity potential of house dust mite was significantly more as compared to house dust. And, as such there was no statistically significant cross - allergenicity between the two groups. CONCLUSION: House dust mite rather than house dust is the main culprit in causing allergic rhinitis. Hence, precautionary and preventive measures to control the exposure to house dust mite can be undertaken

  2. Technical Note: High-resolution mineralogical database of dust-productive soils for atmospheric dust modeling

    Directory of Open Access Journals (Sweden)

    S. Nickovic

    2012-01-01

    Full Text Available Dust storms and associated mineral aerosol transport are driven primarily by meso- and synoptic-scale atmospheric processes. It is therefore essential that the dust aerosol process and background atmospheric conditions that drive dust emissions and atmospheric transport are represented with sufficiently well-resolved spatial and temporal features. The effects of airborne dust interactions with the environment determine the mineral composition of dust particles. The fractions of various minerals in aerosol are determined by the mineral composition of arid soils; therefore, a high-resolution specification of the mineral and physical properties of dust sources is needed.

    Several current dust atmospheric models simulate and predict the evolution of dust concentrations; however, in most cases, these models do not consider the fractions of minerals in the dust. The accumulated knowledge about the impacts of the mineral composition in dust on weather and climate processes emphasizes the importance of including minerals in modeling systems. Accordingly, in this study, we developed a global dataset consisting of the mineral composition of the current potentially dust-producing soils. In our study, we (a mapped mineral data to a high-resolution 30 s grid, (b included several mineral-carrying soil types in dust-productive regions that were not considered in previous studies, and (c included phosphorus.

  3. Documenting DNA in the dust.

    Science.gov (United States)

    Gilbert, M T P

    2017-02-01

    I bought a robotic vacuum cleaner this summer and set it to work. Although my initial expectations were not high, my robot (christened Buddy) finished its cleaning cycle, and then insistently demanded that I empty its dust collection box. As I took the box out, my jaw dropped. I live in a modern house, we don't have pets, and I like to think that I keep it reasonably dust free. But, there was much dust in that box. And when I ran it again 2 days later, the same thing happened. And indeed, every 2 days, Buddy dutifully goes to work, and sucks up a similarly impressive quantity. It's remarkable, and naturally begs the question of where it all comes from? Some is externally derived, entering the house with us or through open windows. Some is clearly fibres shed from clothes, furniture etc. Then there's the skin cells and hair we shed. But at least part is derived from the host of smaller organisms that live in and around our homes, many of which are arthropods (Butte & Heinzow ). I suspect almost all readers are aware that some smaller animals live in our houses - even those who live in the modern urban houses will have occasionally encountered the odd drosophila, silverfish or spider. But I suspect that prior to reading Madden et al.'s article in this issue of Molecular Ecology (Madden et al. ), few of you will have appreciated the true diversity, which, it turns out, is huge. © 2017 John Wiley & Sons Ltd.

  4. How to suppress obsessive thoughts.

    Science.gov (United States)

    Rassin, Eric; Diepstraten, Philip

    2003-01-01

    Thought suppression (i.e. consciously trying to avoid certain thoughts from entering consciousness) has been argued to be an inadequate strategy in case of unwanted intrusions. That is, thought suppression seems to result in more rather than less intrusions. Although this experimental finding has been explained in terms of failing attempts to distract oneself from the target thought, the White Bear Suppression Inventory (WBSI; a scale that measures chronic thought suppression tendencies) does not address the means by which respondents try to suppress unwanted thoughts. To examine which strategies of mental control people use to suppress unwanted thoughts, obsessive-compulsive disorder patients (N=47) completed the WBSI, the Thought Control Questionnaire, and two measures of psychopathology. Results suggest that the crucial mechanism in thought suppression may not be distraction, but self-punishment.

  5. Supernova olivine from cometary dust.

    Science.gov (United States)

    Messenger, Scott; Keller, Lindsay P; Lauretta, Dante S

    2005-07-29

    An interplanetary dust particle contains a submicrometer crystalline silicate aggregate of probable supernova origin. The grain has a pronounced enrichment in 18O/16O (13 times the solar value) and depletions in 17O/16O (one-third solar) and 29Si/28Si (supernova. The aggregate contains olivine (forsterite 83) grains supernova ejecta if several different nucleosynthetic zones mixed in the proper proportions. The supernova grain is also partially encased in nitrogen-15-rich organic matter that likely formed in a presolar cold molecular cloud.

  6. Dust coagulation and fragmentation in molecular clouds I. How collisions between dust aggregates alter the dust size distribution

    NARCIS (Netherlands)

    Ormel, C. W.; Paszun, D.; Dominik, C.; Tielens, A. G. G. M.

    The cores in molecular clouds are the densest and coldest regions of the interstellar medium (ISM). In these regions ISM-dust grains have the potential to coagulate. This study investigates the collisional evolution of the dust population by combining two models: a binary model that simulates the

  7. Interstellar dust in and around the heliosphere

    Science.gov (United States)

    Mann, I.; Czechowski, A.

    The motion of the sun relative to the local interstellar medium causes a stream of interstellar medium dust toward the heliosphere. Small dust particles gain a high charge to mass ratio and are deflected from their original flow direction with the interstellar gas. The majority of interstellar dust particles of sizes below 0.1 micrometer are deflected from entering the heliosphere. A pile-up of interstellar dust similar to that of the hydrogen wall appears around the heliosphere, but is restricted to small grains. We use a simple model of the heliospheric transition region to calculate the velocity distributions of these interstellar grains in the neighborhood of the heliosphere. Different assumptions about the interstellar magnetic field and the structure of the plasma flow are considered. We find that the distributions are sensitive to the structure of the heliospheric transition region, in particular to the presence of a sharp bow shock. Larger interstellar dust particles enter the heliosphere where several deflection mechanisms selectively act on dust particles of certain sizes and properties. When considering the dynamics of small grains that have entered the heliosphere the effects of the heliospheric current sheet (downstream and upstream from the termination shock) and the solar cycle can facilitate the entry of charged grains into the inner solar system, although the unipolar field regions approaching the ecliptic act as an obstacle to it. The dust fluxes in the inner heliosphere also depend on the influence of radiation pressure and solar gravity. The influence of these forces can be seen in the mass distributions of interstellar dust measured in-situ from spacecraft at different locations. The conditions of dust dynamics depend on the initial velocity distribution of grains in the interstellar medium. Small dust particles are coupled to the gas of the interstellar medium while larger dust particles may not be coupled to the local interstellar cloud and

  8. Optical dust sensor for the mining industry

    Science.gov (United States)

    Sierakowski, Marek W.; Wolinski, Tomasz R.; Domanski, Andrzej W.; Osinska, Katarzyna

    2003-04-01

    One of many hazards in mining industry is presence of airborne dust on underground boards. Hazards caused by dust generated and spread in mines are of the two types: (1) health risk for miners from airborne dust produced from rocks, coal, soluble minerals (pneumoconiosis, toxicity), (2) danger of explosion of carbon dust. Dust particles produced in mines underground range from 0 to about 400 micrometers, have irregular shapes and prevailingly are strongly light absorbing. It is assumed that the most health-risky are particles between 1 μm and 5 μm in size. They are not visible with naked eyes, so their control and measurement need technical equipment. As a standard in polish mines, gravimetric measurement method is used at present. This method works well in post-event evaluation of total health-risk factor, but is not much useful for instantaneous risk warning. In order to recognize and possibly prevent the dust risk as it appears, other methods have to be used, like optical method. Looking towards this demand, an experimental optical dust sensor is demonstrated. The sensor is based on light scattering effect by dust particles, as usual do devices of this type. Originality of this solution lies in construction details of the sensor. Scattering is a complex function of dust kind, size, shape and concentration. Moreover, operating conditions of such a device are cruel -- humidity, elevated temperature, vibrations, and over-all contact with dust -- are harmful for optics. Thus, to achieve reliable indications of the sensor is really a challenge. This paper describes optical construction attempting to overcome difficulties in obtaining dust concentration sensor intended for mining industry and similar applications. First laboratory and operational tests are also reported.

  9. Unihemispheric burst suppression

    Directory of Open Access Journals (Sweden)

    Edward C. Mader Jr.

    2014-08-01

    Full Text Available Burst suppression (BS consists of bursts of high-voltage slow and sharp wave activity alternating with periods of background suppression in the electroencephalogram (EEG. When induced by deep anesthesia or encephalopathy, BS is bihemispheric and is often viewed as a non-epileptic phenomenon. In contrast, unihemispheric BS is rare and its clinical significance is poorly understood. We describe here two cases of unihemispheric BS. The first patient is a 56-year-old woman with a left temporoparietal tumor who presented in convulsive status epilepticus. EEG showed left hemispheric BS after clinical seizure termination with lorazepam and propofol. The second patient is a 39-year-old woman with multiple medical problems and a vague history of seizures. After abdominal surgery, she experienced a convulsive seizure prompting treatment with propofol. Her EEG also showed left hemispheric BS. In both cases, increasing the propofol infusion rate resulted in disappearance of unihemispheric BS and clinical improvement. The prevailing view that typical bihemispheric BS is non-epileptic should not be extrapolated automatically to unihemispheric BS. The fact that unihemispheric BS was associated with clinical seizure and resolved with propofol suggests that, in both cases, an epileptic mechanism was responsible for unihemispheric BS.

  10. eblur/dust: a modular python approach for dust extinction and scattering

    Science.gov (United States)

    Corrales, Lia

    2016-03-01

    I will present a library of python codes -- github.com/eblur/dust -- which calculate dust scattering and extinction properties from the IR to the X-ray. The modular interface allows for custom defined dust grain size distributions, optical constants, and scattering physics. These codes are currently undergoing a major overhaul to include multiple scattering effects, parallel processing, parameterized grain size distributions beyond power law, and optical constants for different grain compositions. I use eblur/dust primarily to study dust scattering images in the X-ray, but they may be extended to applications at other wavelengths.

  11. Uniform Dust Distributor for Testing Radiative Emittance of Dust-Coated Surfaces

    Science.gov (United States)

    Hurlbert, Kathryn Miller; Witte, Larry C.; Hollingsworth, D. Keith

    2012-01-01

    This apparatus distributes dust (typical of the Martian surface) in a uniform fashion on the surface of multiple samples simultaneously. The primary innovation is that the amount of dust deposited on the multiple surfaces can be controlled by the time that the apparatus operates, and each sample will be subject to the same amount of dust deposition. The exact weight of dust that is added per unit of sample area is determined by the use of slides that can be removed sequentially after each dusting.

  12. House Dust Mite Respiratory Allergy

    DEFF Research Database (Denmark)

    Calderón, Moisés A; Kleine-Tebbe, Jörg; Linneberg, Allan

    2015-01-01

    Although house dust mite (HDM) allergy is a major cause of respiratory allergic disease, specific diagnosis and effective treatment both present unresolved challenges. Guidelines for the treatment of allergic rhinitis and asthma are well supported in the literature, but specific evidence on the e......Although house dust mite (HDM) allergy is a major cause of respiratory allergic disease, specific diagnosis and effective treatment both present unresolved challenges. Guidelines for the treatment of allergic rhinitis and asthma are well supported in the literature, but specific evidence...... of specific IgE testing, but availability is limited. Treatment options for HDM allergy are limited and include HDM avoidance, which is widely recommended as a strategy, although evidence for its efficacy is variable. Clinical efficacy of pharmacotherapy is well documented; however, symptom relief does...... not extend beyond the end of treatment. Finally, allergen immunotherapy has a poor but improving evidence base (notably on sublingual tablets) and its benefits last after treatment ends. This review identifies needs for deeper physician knowledge on the extent and impact of HDM allergy in respiratory disease...

  13. Comet Dust After Deep Impact

    Science.gov (United States)

    Wooden, Diane H.; Harker, David E.; Woodward, Charles E.

    2006-01-01

    When the Deep Impact Mission hit Jupiter Family comet 9P/Tempel 1, an ejecta crater was formed and an pocket of volatile gases and ices from 10-30 m below the surface was exposed (A Hearn et aI. 2005). This resulted in a gas geyser that persisted for a few hours (Sugita et al, 2005). The gas geyser pushed dust grains into the coma (Sugita et a1. 2005), as well as ice grains (Schulz et al. 2006). The smaller of the dust grains were submicron in radii (0-25.3 micron), and were primarily composed of highly refractory minerals including amorphous (non-graphitic) carbon, and silicate minerals including amorphous (disordered) olivine (Fe,Mg)2SiO4 and pyroxene (Fe,Mg)SiO3 and crystalline Mg-rich olivine. The smaller grains moved faster, as expected from the size-dependent velocity law produced by gas-drag on grains. The mineralogy evolved with time: progressively larger grains persisted in the near nuclear region, having been imparted with slower velocities, and the mineralogies of these larger grains appeared simpler and without crystals. The smaller 0.2-0.3 micron grains reached the coma in about 1.5 hours (1 arc sec = 740 km), were more diverse in mineralogy than the larger grains and contained crystals, and appeared to travel through the coma together. No smaller grains appeared at larger coma distances later (with slower velocities), implying that if grain fragmentation occurred, it happened within the gas acceleration zone. These results of the high spatial resolution spectroscopy (GEMINI+Michelle: Harker et 4. 2005, 2006; Subaru+COMICS: Sugita et al. 2005) revealed that the grains released from the interior were different from the nominally active areas of this comet by their: (a) crystalline content, (b) smaller size, (c) more diverse mineralogy. The temporal changes in the spectra, recorded by GEMIM+Michelle every 7 minutes, indicated that the dust mineralogy is inhomogeneous and, unexpectedly, the portion of the size distribution dominated by smaller grains has

  14. Airborne microorganisms and dust from livestock houses

    NARCIS (Netherlands)

    Zhao, Y.; Aarnink, A.J.A.; Jong, de M.C.M.; Groot Koerkamp, P.W.G.

    2011-01-01

    The objective of this study was to evaluate the efficiencies and suitability of samplers for airborne microorganisms and dust, which could be used in practical livestock houses. Two studies were performed: 1) Testing impaction and cyclone pre-separators for dust sampling in livestock houses; 2)

  15. Measurement of nicotine in household dust

    International Nuclear Information System (INIS)

    Kim, Sungroul; Aung, Ther; Berkeley, Emily; Diette, Gregory B.; Breysse, Patrick N.

    2008-01-01

    An analytical method of measuring nicotine in house dust was optimized and associations among three secondhand smoking exposure markers were evaluated, i.e., nicotine concentrations of both house dust and indoor air, and the self-reported number of cigarettes smoked daily in a household. We obtained seven house dust samples from self-reported nonsmoking homes and 30 samples from smoking homes along with the information on indoor air nicotine concentrations and the number of cigarettes smoked daily from an asthma cohort study conducted by the Johns Hopkins Center for Childhood Asthma in the Urban Environment. House dust nicotine was analyzed by isotope dilution gas chromatography-mass spectrometry (GC/MS). Using our optimized method, the median concentration of nicotine in the dust of self-reported nonsmoking homes was 11.7 ng/mg while that of smoking homes was 43.4 ng/mg. We found a substantially positive association (r=0.67, P<0.0001) between house dust nicotine concentrations and the numbers of cigarettes smoked daily. Optimized analytical methods showed a feasibility to detect nicotine in house dust. Our results indicated that the measurement of nicotine in house dust can be used potentially as a marker of longer term SHS exposure

  16. Dust control effectiveness of drywall sanding tools.

    Science.gov (United States)

    Young-Corbett, Deborah E; Nussbaum, Maury A

    2009-07-01

    In this laboratory study, four drywall sanding tools were evaluated in terms of dust generation rates in the respirable and thoracic size classes. In a repeated measures study design, 16 participants performed simulated drywall finishing tasks with each of four tools: (1) ventilated sander, (2) pole sander, (3) block sander, and (4) wet sponge. Dependent variables of interest were thoracic and respirable breathing zone dust concentrations. Analysis by Friedman's Test revealed that the ventilated drywall sanding tool produced significantly less dust, of both size classes, than did the other three tools. The pole and wet sanders produced significantly less dust of both size classes than did the block sander. The block sander, the most commonly used tool in drywall finishing operations, produced significantly more dust of both size classes than did the other three tools. When compared with the block sander, the other tools offer substantial dust reduction. The ventilated tool reduced respirable concentrations by 88% and thoracic concentrations by 85%. The pole sander reduced respirable concentrations by 58% and thoracic by 50%. The wet sander produced reductions of 60% and 47% in the respirable and thoracic classes, respectively. Wet sponge sanders and pole sanders are effective at reducing breathing-zone dust concentrations; however, based on its superior dust control effectiveness, the ventilated sander is the recommended tool for drywall finishing operations.

  17. Dust Dynamics in Kelvin-Helmholtz Instabilities

    Directory of Open Access Journals (Sweden)

    Keppens Rony

    2013-04-01

    Full Text Available The Kelvin-Helmholtz instability (KHI is a fluid instability which arises when two contacting flows have different tangential velocities. As shearing flows are very common in all sorts of (astrophysical fluid setups, the KHI is frequently encountered. In many astrophysical fluids the gas fluid in loaded with additional dust particles. Here we study the influence of these dust particles on the initiation of the KHI, as well as the effect the KHI has on the density distribution of dust species in a range of different particle sizes. This redistribution by the instability is of importance in the formation of dust structures in astrophysical fluids. To study the effect of dust on the linear and nonlinear phase of the KHI, we use the multi-fluid dust + gas module of the MPI-AMRVAC [1] code to perform 2D and 3D simulations of KHI in setups with physical quantities relevant to astrophysical fluids. A clear dependency on dust sizes is seen, with larger dust particles displaying significantly more clumping than smaller ones.

  18. Role of dust in H II regions

    International Nuclear Information System (INIS)

    Sarazin, C.L.

    1975-01-01

    The purpose of this dissertation is to determine quantitatively the effects of U.V. absorbing dust on H II regions, and compare these effects with observations. Many observations indicate that dust grains are present within H II regions. An analytic theory is presented which describes all three of the effects of dust in H II regions. Although this model is relatively crude, it is useful in determining the approximate size of the modifications due to dust. In order to explore this problem more carefully, detailed numerical models of H II regions with dust were constructed. The ionization and thermal structure of these model H II regions is discussed. The observational consequences of the presence of dust are explored; the optical line intensities, radio continuum and line fluxes, and infrared emission of model H II regions with dust are given. These numerical models are compared with observations of diffuse nebulae. The optical line ratios are compared to several nearby bright H II regions, and it is found that the dust models may explain several anomalies in their spectrum

  19. Where does galactic dust come from?

    Science.gov (United States)

    Ginolfi, M.; Graziani, L.; Schneider, R.; Marassi, S.; Valiante, R.; Dell'Agli, F.; Ventura, P.; Hunt, L. K.

    2018-02-01

    Here we investigate the origin of the dust mass (Mdust) observed in the Milky Way (MW) and of dust scaling relations found in a sample of local galaxies from the DGS and KINGFISH surveys. To this aim, we model dust production from Asymptotic Giant Branch (AGB) stars and supernovae (SNe) in simulated galaxies forming along the assembly of a MW-like halo in a well-resolved cosmic volume of 4 cMpc using the GAMESH pipeline. We explore the impact of different sets of metallicity and mass-dependent AGB and SN dust yields on the predicted Mdust. Our results show that models accounting for grain destruction by the SN reverse shock predict a total dust mass in the MW, that is a factor of ∼4 less than observed, and cannot reproduce the observed galaxy-scale relations between dust and stellar masses, and dust-to-gas ratios and metallicity, with a smaller discrepancy in galaxies with low metallicity (12 + log(O/H) < 7.5) and low stellar masses (Mstar < 107 M⊙). In agreement with previous studies, we suggest that competing processes in the interstellar medium must be at play to explain the observed trends. Our result reinforces this conclusion by showing that it holds independently of the adopted AGB and SN dust yields.

  20. The Fate of Saharan Dust Across the Atlantic and Implications for a Central American Dust Barrier

    Science.gov (United States)

    Nowottnick, E.; Colarco, P.; da Silva, A.; Hlavka, D.; McGill, M.

    2011-01-01

    Saharan dust was observed over the Caribbean basin during the summer 2007 NASA Tropical Composition, Cloud, and Climate Coupling (TC4) field experiment. Airborne Cloud Physics Lidar (CPL) and satellite observations from MODIS suggest a barrier to dust transport across Central America into the eastern Pacific. We use the NASA GEOS-5 atmospheric transport model with online aerosol tracers to perform simulations of the TC4 time period in order to understand the nature of this barrier. Our simulations are driven by the Modem Era Retrospective-Analysis for Research and Applications (MERRA) meteorological analyses. We evaluate our baseline simulated dust distributions using MODIS and CALIOP satellite and ground-based AERONET sun photometer observations. GEOS-5 reproduces the observed location, magnitude, and timing of major dust events, but our baseline simulation does not develop as strong a barrier to dust transport across Central America as observations suggest. Analysis of the dust transport dynamics and lost processes suggest that while both mechanisms play a role in defining the dust transport barrier, loss processes by wet removal of dust are about twice as important as transport. Sensitivity analyses with our model showed that the dust barrier would not exist without convective scavenging over the Caribbean. The best agreement between our model and the observations was obtained when dust wet removal was parameterized to be more aggressive, treating the dust as we do hydrophilic aerosols.

  1. Extracting lunar dust parameters from image charge signals produced by the Lunar Dust Experiment

    Science.gov (United States)

    Stanley, J.; Kempf, S.; Horanyi, M.; Szalay, J.

    2015-12-01

    The Lunar Dust Experiment (LDEX) onboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) is an impact ionization dust detector used to characterize the lunar dust exosphere generated by the impacts of large interplanetary particles and meteor streams (Horanyi et al., 2015). In addition to the mass and speed of these lofted particles, LDEX is sensitive to their charge. The resulting signatures of impact events therefore provide valuable information about not only the ambient plasma environment, but also the speed vectors of these dust grains. Here, impact events produced from LDEX's calibration at the Dust Accelerator Laboratory are analyzed using an image charge model derived from the electrostatic simulation program, Coulomb. We show that parameters such as dust grain speed, size, charge, and position of entry into LDEX can be recovered and applied to data collected during LADEE's seven-month mission.

  2. ULYSSES DUST DETECTION SYSTEM V2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Dataset Overview ================ This data set contains information on dust the dust environment in interplanetary space within the inner solar system, between...

  3. Dust radiative effects on atmospheric thermodynamics and tropical cyclogenesis over the Atlantic Ocean using WRF-Chem coupled with an AOD data assimilation system

    Science.gov (United States)

    Chen, Dan; Liu, Zhiquan; Davis, Chris; Gu, Yu

    2017-06-01

    This study investigated the dust radiative effects on atmospheric thermodynamics and tropical cyclogenesis over the Atlantic Ocean using the Weather Research and Forecasting Model with Chemistry (WRF-Chem) coupled with an aerosol data assimilation (DA) system. MODIS AOD (aerosol optical depth) data were assimilated with the Gridpoint Statistical Interpolation (GSI) three-dimensional variational (3DVAR) DA scheme to depict the Saharan dust outbreak events in the 2006 summer. Comparisons with Ozone Monitoring Instrument (OMI), AErosol RObotic NETwork (AERONET), and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) observations showed that the system was capable of reproducing the dust distribution. Two sets of 180 h forecasts were conducted with the dust radiative effects activated (RE_ON) and inactivated (RE_OFF) respectively. Differences between the RE_ON and RE_OFF forecasts showed that low-altitude (high-altitude) dust inhibits (favors) convection owing to changes in convective inhibition (CIN). Heating in dust layers immediately above the boundary layer increases inhibition, whereas sufficiently elevated heating allows cooling above the boundary layer that reduces convective inhibition. Semi-direct effects in which clouds are altered by thermodynamic changes are also noted, which then alter cloud-radiative temperature (T) changes. The analysis of a tropical cyclone (TC) suppression case on 5 September shows evidence of enhanced convective inhibition by direct heating in dust, but it also suggests that the low-predictability dynamics of moist convection reduces the determinism of the effects of dust on timescales of TC development (days).

  4. Dust Evolution in Intermediate Velocity Clouds

    Science.gov (United States)

    Pinheiro Gonçalves, D.; Martin, P. G.; Blagrave, K.; Miville-Deschenes, M. A.

    We search for evidence of dust evolution in high Galactic latitude regions by looking at variations in the emissivities of dust associated with different velocity clouds. In order to do so, we spatially correlate infrared IRAS/IRIS dust maps with HI column density maps derived from 21-cm radio observations with the GBT. Our findings show that intermediate velocity clouds (IVCs or halo clouds) have a higher 60µm/100µm and lower 12µm/100µm color ratio when compared to dust in local low-velocity gas. This suggests that large thermal dust grains are shattered into smaller ones (VSGs) and that there is a low relative abundance of PAHs in IVCs.

  5. Recycling of steelmaking dusts: The Radust concept

    Directory of Open Access Journals (Sweden)

    Jalkanen H.

    2005-01-01

    Full Text Available Recycling of dusts and other wastes of steelmaking is becoming to a necessity of two reasons: due to high contents of iron oxides dusts are valuable raw material for steelmaking and tightening environmental legislation makes the landfill disposal of wastes more expensive. Fine dust fractions from various stages of steelmaking route contain besides iron and carbon heavy metals especially zinc and lead and heavy hydrocarbons that are acceptable neither for landfill disposal nor for recycling back to processes without any spe4cial treatments. Some theoretical and practical aspects concerning high temperature treatments of steelmaking dusts for removal of hazardous components and production of clean high iron raw material for recycling is discussed in this paper. The Radust technology developed at Koverhar steelwork in Finland for treatment of the most problematic fine fractions of blast furnace and oxygen converter dusts is shortly presented and discussed.

  6. House dust mite control measures for asthma

    DEFF Research Database (Denmark)

    Gøtzsche, Peter C.; Johansen, Helle Krogh

    2008-01-01

    BACKGROUND: The major allergen in house dust comes from mites. Chemical, physical and combined methods of reducing mite allergen levels are intended to reduce asthma symptoms in people who are sensitive to house dust mites. OBJECTIVES: To assess the effects of reducing exposure to house dust mite...... antigens in the homes of people with mite-sensitive asthma. SEARCH STRATEGY: PubMed and The Cochrane Library (last searches Nov 2007), reference lists. SELECTION CRITERIA: Randomised trials of mite control measures vs placebo or no treatment in people with asthma known to be sensitive to house dust mites.......07), or in medication usage (standardised mean difference -0.06, 95% CI -0.18 to 0.07). AUTHORS' CONCLUSIONS: Chemical and physical methods aimed at reducing exposure to house dust mite allergens cannot be recommended. It is doubtful whether further studies, similar to the ones in our review, are worthwhile. If other...

  7. Mesospheric dust observations during the MAXIDUSTY campaign

    Science.gov (United States)

    Antonsen, Tarjei; Havnes, Ove; Fredriksen, Åshild; Friedrich, Martin; Sternovsky, Zoltan; Plane, John; Hartquist, Tom; Olsen, Sveinung; Eilertsen, Yngve; Trondsen, Espen; Mann, Ingrid; Hedin, Jonas; Gumbel, Jörg; Moen, Jøran; Latteck, Ralph; Baumgarten, Gerd; Höffner, Josef; Williams, Bifford; Hoppe, Ulf-Peter; Karlberg, Jan-Ove

    2017-04-01

    The MAXIDUSTY rocket payloads, launched from Andøya June 30 and July 8 2016, were equipped with dust impact detectors aiming to characterize mesospheric dust charge state, mass distribution of impact fragments and NLC/PMSE structure. One of the main scientific objectives for the campaign was to confirm that material of meteoric origin is abundant inside the icy mesospheric dust particles. The rockets were launched simultaneously with PMSE and NLC (MAXIDUSTY-1) and PMSE (MAXIDUSTY-1B) respectively, and radar measurements were made coincident with the rocket flight path. We report here on the initial results from the rocket probes and remote soundings, with emphasis on the dust impact detector results. Results from the Multiple Dust Detector (MUDD) confirm that NLC ice particles probably have a relatively high content of meteoric smoke particles with a filling factor of up to several percent. Comparisons of the DUSTY faraday bucket and PMSE show that there is no simple correlation between the two.

  8. Heating of Porous Icy Dust Aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Sirono, Sin-iti [Earth and Environmental Sciences, Nagoya University, Tikusa-ku, Furo-cho, Nagoya 464-8601 (Japan)

    2017-06-10

    At the beginning of planetary formation, highly porous dust aggregates are formed through coagulation of dust grains. Outside the snowline, the main component of an aggregate is H{sub 2}O ice. Because H{sub 2}O ice is formed in amorphous form, its thermal conductivity is extremely small. Therefore, the thermal conductivity of an icy dust aggregate is low. There is a possibility of heating inside an aggregate owing to the decay of radionuclides. It is shown that the temperature increases substantially inside an aggregate, leading to crystallization of amorphous ice. During the crystallization, the temperature further increases sufficiently to continue sintering. The mechanical properties of icy dust aggregates change, and the collisional evolution of dust aggregates is affected by the sintering.

  9. Metal content in street dust as a reflection of atmospheric dust emissions from coal power plants, metal smelters, and traffic

    OpenAIRE

    Žibret, Gorazd; Van Tonder, Danel; Žibret, Lea

    2012-01-01

    Resuspended street dust is a source of inhalable particles in urban environments. Despite contaminated street dust being a possible health risk factor for local population, little is known about the contribution of atmospheric dust emissions and other factors to the content of toxic metals in street dust. The impact of smelting, traffic, and power plants on metal contaminates in street dust is the focus of street dust sampling at 46 locations in the Witbank area (Republic...

  10. High Latitude Dust in the Earth System

    Science.gov (United States)

    Bullard, Joanna E.; Baddock, Matthew; Bradwell, Tom; Crusius, John; Darlington, Eleanor; Gaiero, Diego; Gasso, Santiago; Gisladottir, Gudrun; Hodgkins, Richard; McCulloch, Robert; hide

    2016-01-01

    Natural dust is often associated with hot, subtropical deserts, but significant dust events have been reported from cold, high latitudes. This review synthesizes current understanding of high-latitude (> or = 50degN and > or = 40degS) dust source geography and dynamics and provides a prospectus for future research on the topic. Although the fundamental processes controlling aeolian dust emissions in high latitudes are essentially the same as in temperate regions, there are additional processes specific to or enhanced in cold regions. These include low temperatures, humidity, strong winds, permafrost and niveo-aeolian processes all of which can affect the efficiency of dust emission and distribution of sediments. Dust deposition at high latitudes can provide nutrients to the marine system, specifically by contributing iron to high-nutrient, low-chlorophyll oceans; it also affects ice albedo and melt rates. There have been no attempts to quantify systematically the expanse, characteristics, or dynamics of high-latitude dust sources. To address this, we identify and compare the main sources and drivers of dust emissions in the Northern (Alaska, Canada, Greenland, and Iceland) and Southern (Antarctica, New Zealand, and Patagonia) Hemispheres. The scarcity of year-round observations and limitations of satellite remote sensing data at high latitudes are discussed. It is estimated that under contemporary conditions high-latitude sources cover >500,000 sq km and contribute at least 80-100 Tg/yr1 of dust to the Earth system (approx. 5% of the global dust budget); both are projected to increase under future climate change scenarios.

  11. Ocular toxicity of authentic lunar dust

    Science.gov (United States)

    2012-01-01

    Background Dust exposure is a well-known occupational hazard for terrestrial workers and astronauts alike and will continue to be a concern as humankind pursues exploration and habitation of objects beyond Earth. Humankind’s limited exploration experience with the Apollo Program indicates that exposure to dust will be unavoidable. Therefore, NASA must assess potential toxicity and recommend appropriate mitigation measures to ensure that explorers are adequately protected. Visual acuity is critical during exploration activities and operations aboard spacecraft. Therefore, the present research was performed to ascertain the ocular toxicity of authentic lunar dust. Methods Small (mean particle diameter = 2.9 ± 1.0 μm), reactive lunar dust particles were produced by grinding bulk dust under ultrapure nitrogen conditions. Chemical reactivity and cytotoxicity testing were performed using the commercially available EpiOcularTM assay. Subsequent in vivo Draize testing utilized a larger size fraction of unground lunar dust that is more relevant to ocular exposures (particles testing indicated minimal irritancy potential based on the time required to reduce cell viability by 50% (ET50). Follow-up testing using the Draize standard protocol confirmed that the lunar dust was minimally irritating. Minor irritation of the upper eyelids was noted at the 1-hour observation point, but these effects resolved within 24 hours. In addition, no corneal scratching was observed using fluorescein stain. Conclusions Low-titanium mare lunar dust is minimally irritating to the eyes and is considered a nuisance dust for ocular exposure. No special precautions are recommended to protect against ocular exposures, but fully shielded goggles may be used if dust becomes a nuisance. PMID:22817808

  12. Suppression of sympathetic detonation

    Science.gov (United States)

    Foster, J. C., Jr.; Gunger, M. E.; Craig, B. G.; Parsons, G. H.

    1984-08-01

    There are two basic approaches to suppression of sympathetic detonation. Minimizing the shock sensitivity of the explosive to long duration pressure will obviously reduce interround separation distances. However, given that the explosive sensitivity is fixed, then much can be gained through the use of simple barriers placed between the rounds. Researchers devised calculational methods for predicting shock transmission; experimental methods have been developed to characterize explosive shock sensitivity and observe the response of acceptors to barriers. It was shown that both EAK and tritonal can be initiated to detonation with relatively low pressure shocks of long durations. It was also shown that to be an effective barrier between the donor and acceptor, the material must attenuate shock and defect fragments. Future actions will concentrate on refining the design of barriers to minimize weight, volume, and cost.

  13. Numerical Modeling of Topography-Modulated Dust Aerosol Distribution and Its Influence on the Onset of East Asian Summer Monsoon

    Directory of Open Access Journals (Sweden)

    Hui Sun

    2016-01-01

    Full Text Available A regional climate model coupled with a dust module was used to simulate dust aerosol distribution and its effects on the atmospheric heat source over the TP, East Asian summer monsoon onset, and precipitation in East Asia modulated by the uplift of the northern TP. We carried out four experiments, including a modern (i.e., high-mountain experiment with (HMD and without (HM the major deserts in Northwest China and a low-mountain experiment with (LMD and without (LM the deserts. The results show that dust greatly increases in the Taklamakan Desert accompanied with the uplift of the northern TP, and the increase exceeds 150 µg kg−1 in spring. A strong cyclone in the Tarim Basin produced by the uplifted northern TP enhances dust emissions in the Taklamakan Desert in summer. Meanwhile, the dust loading over the TP also increases induced by the uplift of the northern TP, causing the heat source over the TP decreased. Under the condition of the northern TP uplift to present altitude, dust delays the East Asia summer monsoon onset by two pentads and one pentad, respectively, in the southern and northern monsoon regions and greatly suppresses precipitation in East Asia compared with results in the low terrain experiments.

  14. Asian dust events of April 1998

    Science.gov (United States)

    Husar, R.B.; Tratt, D.M.; Schichtel, B.A.; Falke, S.R.; Li, F.; Jaffe, D.; Gasso, S.; Gill, T.; Laulainen, N.S.; Lu, F.; Reheis, M.C.; Chun, Y.; Westphal, D.; Holben, B.N.; Gueymard, C.; McKendry, I.; Kuring, N.; Feldman, G.C.; McClain, C.; Frouin, R.J.; Merrill, J.; DuBois, D.; Vignola, F.; Murayama, T.; Nickovic, S.; Wilson, W.E.; Sassen, K.; Sugimoto, N.; Malm, W.C.

    2001-01-01

    On April 15 and 19, 1998, two intense dust storms were generated over the Gobi desert by springtime low-pressure systems descending from the northwest. The windblown dust was detected and its evolution followed by its yellow color on SeaWiFS satellite images, routine surface-based monitoring, and through serendipitous observations. The April 15 dust cloud was recirculating, and it was removed by a precipitating weather system over east Asia. The April 19 dust cloud crossed the Pacific Ocean in 5 days, subsided to the surface along the mountain ranges between British Columbia and California, and impacted severely the optical and the concentration environments of the region. In east Asia the dust clouds increased the albedo over the cloudless ocean and land by up to 10-20%, but it reduced the near-UV cloud reflectance, causing a yellow coloration of all surfaces. The yellow colored backscattering by the dust eludes a plausible explanation using simple Mie theory with constant refractive index. Over the West Coast the dust layer has increased the spectrally uniform optical depth to about 0.4, reduced the direct solar radiation by 30-40%, doubled the diffuse radiation, and caused a whitish discoloration of the blue sky. On April 29 the average excess surface-level dust aerosol concentration over the valleys of the West Coast was about 20-50 ??g/m3 with local peaks >100 ??g/m3. The dust mass mean diameter was 2-3 ??m, and the dust chemical fingerprints were evident throughout the West Coast and extended to Minnesota. The April 1998 dust event has impacted the surface aerosol concentration 2-4 times more than any other dust event since 1988. The dust events were observed and interpreted by an ad hoc international web-based virtual community. It would be useful to set up a community-supported web-based infrastructure to monitor the global aerosol pattern for such extreme aerosol events, to alert and to inform the interested communities, and to facilitate collaborative

  15. Health effects from exposure to atmospheric mineral dust near Las Vegas, NV, USA

    Directory of Open Access Journals (Sweden)

    Deborah E. Keil

    Full Text Available Desert areas are usually characterized by a continuous deposition of fine airborne particles. Over time, this process results in the accumulation of silt and clay on desert surfaces. We evaluated health effects associated with regional atmospheric dust, or geogenic dust, deposited on surfaces in the Nellis Dunes Recreation Area (NDRA in Clark County, Nevada, a popular off-road vehicle (ORV recreational site frequented daily by riders, families, and day campers. Because of atmospheric mixing and the mostly regional origin of the accumulated particles, the re-suspended airborne dust is composed of a complex mixture of minerals and metals including aluminum, vanadium, chromium, manganese, iron, cobalt, copper, zinc, arsenic, strontium, cesium, lead, uranium, and others. Geogenic dust with a median diameter of 4.1 μm was administered via oropharyngeal aspiration to female B6C3F1 mice at doses of 0.01 to 100 mg dust/kg body weight, four times, a week apart, for 28-days. Immuno- and neurotoxicological outcomes 24 h following the last exposure were evaluated. Antigen-specific IgM responses were dose-responsively suppressed at 0.1, 1.0, 10 and 100 mg/kg/day. Splenic and thymic lymphocytic subpopulations and natural killer cell activity also were significantly reduced. Antibodies against MBP, NF-68, and GFAP were not affected, while brain CD3+ T cells were decreased in number. A lowest observed adverse effect level (LOAEL of 0.1 mg/kg/day and a no observed adverse effect level (NOAEL of 0.01 mg/kg/day were derived based on the antigen-specific IgM responses. Keywords: Geogenic dust, Heavy metals, Minerals, Lung exposure, Immunotoxicity, Neurotoxicity

  16. Strongly coupled dust coulomb clusters

    International Nuclear Information System (INIS)

    Juan Wentau; Lai Yingju; Chen Mingheng; I Lin

    1999-01-01

    The structures and motions of quasi-2-dimensional strongly coupled dust Coulomb clusters with particle number N from few to hundreds in a cylindrical rf plasma trap are studied and compared with the results from the molecular dynamic simulation using more ideal models. Shell structures with periodic packing in different shells and intershell rotational motion dominated excitations are observed at small N. As N increases, the boundary has less effect, the system recovers to the triangular lattice with isotropic vortex type cooperative excitations similar to an infinite N system except the outer shell region. The above generic behaviors are mainly determined by the system symmetry and agree with the simulation results. The detailed interaction form causes minor effect such as the fine structure of packing

  17. The fate of saharan dust across the atlantic and implications for a central american dust barrier

    Directory of Open Access Journals (Sweden)

    E. Nowottnick

    2011-08-01

    Full Text Available Saharan dust was observed over the Caribbean basin during the summer 2007 NASA Tropical Composition, Cloud, and Climate Coupling (TC4 field experiment. Airborne Cloud Physics Lidar (CPL and satellite observations from MODIS suggest a barrier to dust transport across Central America into the eastern Pacific. We use the NASA GEOS-5 atmospheric transport model with online aerosol tracers to perform simulations of the TC4 time period in order to understand the nature of this barrier. Our simulations are driven by the Modern Era Retrospective-Analysis for Research and Applications (MERRA meteorological analyses. Compared to observations from MODIS and CALIOP, GEOS-5 reproduces the observed location and magnitude of observed dust events, but our baseline simulation does not develop as strong a barrier to dust transport across Central America as observations suggest. Analysis of the dust transport dynamics and loss processes suggest that while both mechanisms play a role in defining the dust transport barrier, loss processes by wet removal of dust are about twice as important as transport. Sensitivity analyses with our model showed that the dust barrier would not exist without convective scavenging over the Caribbean. The best agreement between our model and the observations was obtained when dust wet removal was parameterized to be more aggressive, treating the dust as we do hydrophilic aerosols.

  18. Inactivation of dust mites, dust mite allergen, and mold from carpet.

    Science.gov (United States)

    Ong, Kee-Hean; Lewis, Roger D; Dixit, Anupma; MacDonald, Maureen; Yang, Mingan; Qian, Zhengmin

    2014-01-01

    Carpet is known to be a reservoir for biological contaminants, such as dust mites, dust mite allergen, and mold, if it is not kept clean. The accumulation of these contaminants in carpet might trigger allergies or asthma symptoms in both children and adults. The purpose of this study is to compare methods for removal of dust mites, dust mite allergens, and mold from carpet. Carpets were artificially worn to simulate 1 to 2 years of wear in a four-person household. The worn carpets were inoculated together with a common indoor mold (Cladosporium species) and house dust mites and incubated for 6 weeks to allow time for dust mite growth on the carpet. The carpets were randomly assigned to one of the four treatment groups. Available treatment regimens for controlling carpet contaminants were evaluated through a literature review and experimentation. Four moderately low-hazard, nondestructive methods were selected as treatments: vacuuming, steam-vapor, Neem oil (a natural tree extract), and benzalkonium chloride (a quaternary ammonium compound). Steam vapor treatment demonstrated the greatest dust mite population reduction (p mite allergens (p = 0.084), but have higher efficacy when compared to the chemical method on dust mite allergens (p = 0.002). There is no statistically significant difference in the efficacy for reducing mold in carpet (p > 0.05) for both physical and chemical methods. The steam-vapor treatment effectively killed dust mites and denatured dust mite allergen in the laboratory environment.

  19. An Assessment of the Efficiency of Dust Regional Modelling to Predict Saharan Dust Transport Episodes

    Directory of Open Access Journals (Sweden)

    D. K. Papanastasiou

    2010-01-01

    Full Text Available Aerosol levels at Mediterranean Basin are significantly affected by desert dust that is eroded in North Africa and is transported northwards. This study aims to assess the performance of the Dust REgional Atmospheric Model (BSC-DREAM8b in the prediction of dust outbreaks near the surface in Eastern Mediterranean. For this purpose, model PM10 predictions covering a 7-year period and PM10 observations at five surface monitoring sites in Greece are used. A quantitative criterion is set to select the significant dust outbreaks defined as those when the predicted PM10 surface concentration exceeds 12 μg/m3. The analysis reveals that significant dust transport is usually observed for 1–3 consecutive days. Dust outbreak seasons are spring and summer, while some events are also forecasted in autumn. The seasonal variability of dust transport events is different at Finokalia, where the majority of events are observed in spring and winter. Dust contributes by 19–25% to the near surface observed PM10 levels, which can be increased to more than 50 μg/m3 during dust outbreaks, inducing violations of the air quality standards. Dust regional modeling can be regarded as a useful tool for air quality managers when assessing compliance with air quality limit values.

  20. Dust in the planetary system: Dust interactions in space plasmas of the solar system

    Science.gov (United States)

    Mann, Ingrid; Meyer-Vernet, Nicole; Czechowski, Andrzej

    2014-03-01

    Cosmic dust particles are small solid objects observed in the solar planetary system and in many astronomical objects like the surrounding of stars, the interstellar and even the intergalactic medium. In the solar system the dust is best observed and most often found within the region of the orbits of terrestrial planets where the dust interactions and dynamics are observed directly from spacecraft. Dust is observed in space near Earth and also enters the atmosphere of the Earth where it takes part in physical and chemical processes. Hence space offers a laboratory to study dust-plasma interactions and dust dynamics. A recent example is the observation of nanodust of sizes smaller than 10 nm. We outline the theoretical considerations on which our knowledge of dust electric charges in space plasmas are founded. We discuss the dynamics of the dust particles and show how the small charged particles are accelerated by the solar wind that carries a magnetic field. Finally, as examples for the space observation of cosmic dust interactions, we describe the first detection of fast nanodust in the solar wind near Earth orbit and the first bi-static observations of PMSE, the radar echoes that are observed in the Earth ionosphere in the presence of charged dust.

  1. The Spatial Variation of Dust Particulate Matter Concentrations during Two Icelandic Dust Storms in 2015

    Directory of Open Access Journals (Sweden)

    Pavla Dagsson-Waldhauserova

    2016-06-01

    Full Text Available Particulate matter mass concentrations and size fractions of PM1, PM2.5, PM4, PM10, and PM15 measured in transversal horizontal profile of two dust storms in southwestern Iceland are presented. Images from a camera network were used to estimate the visibility and spatial extent of measured dust events. Numerical simulations were used to calculate the total dust flux from the sources as 180,000 and 280,000 tons for each storm. The mean PM15 concentrations inside of the dust plumes varied from 10 to 1600 µg·m−3 (PM10 = 7 to 583 µg·m−3. The mean PM1 concentrations were 97–241 µg·m−3 with a maximum of 261 µg·m−3 for the first storm. The PM1/PM2.5 ratios of >0.9 and PM1/PM10 ratios of 0.34–0.63 show that suspension of volcanic materials in Iceland causes air pollution with extremely high PM1 concentrations, similar to polluted urban areas in Europe or Asia. Icelandic volcanic dust consists of a higher proportion of submicron particles compared to crustal dust. Both dust storms occurred in relatively densely inhabited areas of Iceland. First results on size partitioning of Icelandic dust presented here should challenge health authorities to enhance research in relation to dust and shows the need for public dust warning systems.

  2. On the reflectance of dust in comets

    Science.gov (United States)

    Zubko, Evgenij; Videen, Gorden; Shkuratov, Yuriy; Hines, Dean C.

    2017-11-01

    Reflectance of cometary dust is a key parameter used in the characterization of comets. In the literature, the reflectance of single-scattering cometary dust particles is widely assumed to be the same as that of the cometary nucleus. We discuss this assumption and demonstrate its inconsistency with photometric observations of comets, laboratory optical measurements, and numerical simulation of light scattering from single-scattering dust particles and particulate surfaces composed of the same particles. We estimate the reflectance of cometary dust particles using a comprehensive physical model of polarization measured in comets over wide range of phase angle and at different wavelengths in the visible. The model predicts that the reflectance of dust in comets inversely correlates with their maximum of positive polarization Pmax. We find that even the darkest dust particles appearing in comets with the highest Pmax, reflect considerably more incident solar-radiation energy, up to 200%, compared to what is thought for cometary nuclei. We also find that the reflectance retrieved from polarimetry in the visible appears in good quantitative accordance with previous estimations from infrared observations of comets. Our findings suggest that the dust production of comets is currently overestimated and may require revision.

  3. Electric Field Generation in Martian Dust Devils

    Science.gov (United States)

    Barth, Erika L.; Farrell, William M.; Rafkin, Scot C. R.

    2015-01-01

    Terrestrial dust devils are known to generate electric fields from the vertical separation of charged dust particles. The particles present within the dust devils on Mars may also be subject to similar charging processes and so likely contribute to electric field generation there as well. However, to date, no Marsin situ instrumentation has been deployed to measure electric field strength. In order to explore the electric environment of dust devils on Mars, the triboelectric dust charging physics from the MacroscopicTriboelectric Simulation (MTS) code has been coupled to the Mars Regional Atmospheric ModelingSystem (MRAMS). Using this model, we examine how macroscopic electric fields are generated within martian dust disturbances and attempt to quantify the time evolution of the electrodynamical system.Electric fields peak for several minutes within the dust devil simulations. The magnitude of the electric field is a strong function of the size of the particles present, the average charge on the particles and the number of particles lifted. Varying these parameters results in peak electric fields between tens of millivolts per meter and tens of kilovolts per meter.

  4. House Dust Mites in Erzincan Province.

    Science.gov (United States)

    Zeytun, Erhan; Doğan, Salih; Aykut, Medeni; Özçiçek, Fatih; Ünver, Edhem; Özçiçek, Adalet

    2015-06-01

    We aimed to determine the species of the house dust mites seen in Erzincan, the number of mites per gram of dust in the houses, and the relationship between temperature and the number of mite specimens. For this purpose, 54 dust samples collected from 18 houses located in different districts of Erzincan province between November 2013 and January 2014. These samples were examined by a lactic acid precipitation method. Of the houses in which the dust samples were collected, 94.44% were found to be positive in terms of mites. A total of 844 mite specimens were isolated from the dust samples, and the mean number of mites per gram of dust was found to be 18.34. The most common species was found to be Acarus siro (55.55%) and was followed by Dermatophagoides pteronyssinus (50.00%), Tyrophagus putrescentiae (22.22%), Histiostoma sp. (22.22%), Lepidoglyphus destructor (16.66%), T. perniciosus(11.11%), Euroglyphus maynei (11.11%), Glycyphagus privatus (11.11%), Cheyletus sp. (11.11%), Tarsonemus sp. (11.11%), and Tetranychus sp. (11.11%). Mite-holding rate of the houses in Erzincan province was found to be 94.44%. The mean number of mites per gram of dust was found to be 18.34. The most common mite species was A. siro, which was followed by D. pteronyssinus.

  5. Featured Image: Making Dust in the Lab

    Science.gov (United States)

    Kohler, Susanna

    2017-12-01

    This remarkable photograph (which spans only 10 m across; click for a full view) reveals what happens when you form dust grains in a laboratory under conditions similar to those of interstellar space. The cosmic life cycle of dust grains is not well understood we know that in the interstellar medium (ISM), dust is destroyed at a higher rate than it is produced by stellar sources. Since the amount of dust in the ISM stays constant, however, there must be additional sources of dust production besides stars. A team of scientists led by Daniele Fulvio (Pontifical Catholic University of Rio de Janeiro and the Max Planck Institute for Astronomy at the Friedrich Schiller University Jena) have now studied formation mechanisms of dust grains in the lab by mimicking low-temperature ISM conditions and exploring how, under these conditions, carbonaceous materials condense from gas phase to form dust grains. To read more about their results and see additional images, check out the paper below.CitationDaniele Fulvio et al 2017 ApJS 233 14. doi:10.3847/1538-4365/aa9224

  6. Subtropical Dust Storms and Downslope Wind Events

    Science.gov (United States)

    Pokharel, Ashok Kumar; Kaplan, Michael L.; Fiedler, Stephanie

    2017-10-01

    We performed detailed mesoscale observational analyses and Weather Research and Forecasting (WRF) model simulations to study the terrain-induced downslope winds that generated dust-emitting winds at the beginning of three strong subtropical dust storms in three distinctly different regions of North Africa and the Arabian Peninsula. We revisit the Harmattan dust storm of 2 March 2004, the Saudi dust storm of 9 March 2009, and the Bodélé Depression dust storm of 8 December 2011 and use high-resolution WRF modeling to assess the dynamical processes during the onset of the storms in more depth. Our results highlight the generation of terrain-induced downslope winds in response to the transition of the atmospheric flow from a subcritical to supercritical state in all three cases. These events precede the unbalanced adjustment processes in the lee of the mountain ranges that produced larger-scale dust aerosol mobilization and transport. We see that only the higher-resolution data sets can resolve the mesoscale processes, which are mainly responsible for creating strong low-level terrain-induced downslope winds leading to the initial dust storms.

  7. Pebble Bed Reactor Dust Production Model

    Energy Technology Data Exchange (ETDEWEB)

    Abderrafi M. Ougouag; Joshua J. Cogliati

    2008-09-01

    The operation of pebble bed reactors, including fuel circulation, can generate graphite dust, which in turn could be a concern for internal components; and to the near field in the remote event of a break in the coolant circuits. The design of the reactor system must, therefore, take the dust into account and the operation must include contingencies for dust removal and for mitigation of potential releases. Such planning requires a proper assessment of the dust inventory. This paper presents a predictive model of dust generation in an operating pebble bed with recirculating fuel. In this preliminary work the production model is based on the use of the assumption of proportionality between the dust production and the normal force and distance traveled. The model developed in this work uses the slip distances and the inter-pebble forces computed by the authors’ PEBBLES. The code, based on the discrete element method, simulates the relevant static and kinetic friction interactions between the pebbles as well as the recirculation of the pebbles through the reactor vessel. The interaction between pebbles and walls of the reactor vat is treated using the same approach. The amount of dust produced is proportional to the wear coefficient for adhesive wear (taken from literature) and to the slip volume, the product of the contact area and the slip distance. The paper will compare the predicted volume with the measured production rates. The simulation tallies the dust production based on the location of creation. Two peak production zones from intra pebble forces are predicted within the bed. The first zone is located near the pebble inlet chute due to the speed of the dropping pebbles. The second peak zone occurs lower in the reactor with increased pebble contact force due to the weight of supported pebbles. This paper presents the first use of a Discrete Element Method simulation of pebble bed dust production.

  8. SPARCLE: Electrostatic Tool for Lunar Dust Control

    International Nuclear Information System (INIS)

    Clark, P. E.; Curtis, S. A.; Minetto, F.; Cheung, C. Y.; Keller, J. F.; Moore, M.; Calle, C. I.

    2009-01-01

    Successful exploration of most planetary surfaces, with their impact-generated dusty regoliths, will depend on the capabilities to keep surfaces free of the dust which could compromise performance and to collect dust for characterization. Solving the dust problem is essential before we return to the Moon. During the Apollo missions, the discovery was made that regolith fines, or dust, behaved like abrasive velcro, coating surfaces, clogging mechanisms, and making movement progressively more difficult as it was mechanically stirred up during surface operations, and abrading surfaces, including spacesuits, when attempts were made to remove it manually. In addition, some of the astronauts experienced breathing difficulties when exposed to dust that got into the crew compartment. The successful strategy will deal with dust dynamics resulting from interaction between mechanical and electrostatic forces. Here we will describe the surface properties of dust particles, the basis for their behavior, and an electrostatically-based approach and methodology for addressing this issue confirmed by our preliminary results. Our device concept utilizes a focused electron beam to control the electrostatic potential of the surface. A plate of the opposite potential is then used to induce dust migration in the presence of an electrical field. Our goal is a compact device of <5 kg mass and using <5 watts of power to be operational in <5 years with heritage from ionic sweepers for active spacecraft potential control (e.g., on POLAR). Rovers could be fitted with devices that could harness the removal of dust for sampling as part of the extended exploration process on Mercury, Mars, asteroids or outer solar system satellites, as well as the Moon.

  9. An Alternative to Thought Suppression?

    Science.gov (United States)

    Boice, Robert

    2012-01-01

    Comments on the original article, "Setting free the bears: Escape from thought suppression," by D. M. Wegner (see record 2011-25622-008). While Wegner supposed that we might have to learn to live with bad thoughts, the present author discusses the use of imagination and guided imagery as an alternative to forced thought suppression.

  10. Backscattering Moessbauer spectroscopy of Martian dust

    International Nuclear Information System (INIS)

    Bertelsen, P.; Madsen, M. B.; Binau, C. S.; Goetz, W.; Gunnlaugsson, H. P.; Hviid, S. F.; Kinch, K. M.; Klingelhoefer, G.; Leer, K.; Madsen, D. E.; Merrison, J.; Olsen, M.; Squyres, S. W.

    2005-01-01

    We report on the determination of the mineralogy of the atmospherically suspended Martian dust particles using backscattering 57 Fe Moessbauer spectroscopy on dust accumulated onto the magnets onboard the Mars Exploration Rovers. The spectra can be interpreted in terms of minerals of igneous origin, and shows only limited, if any, amounts of secondary minerals that may have formed in the presence of liquid water. These findings suggest that the dust has formed in a dry environment over long time in the history of the planet.

  11. Dust and radon: the legal implications

    International Nuclear Information System (INIS)

    Van Sittert, J.M.O.

    1990-01-01

    It is known that radon gas is not generally considered to be a major problem when encountered in the working environment. However, in its process of decay, a series of four short lived daughter products are formed. In a dust-laden atmosphere these daughter products, which are ionized readily, attach to the particulate material and when inhaled are deposited in the alveoli of the lungs. Therefore, if respirable dust is controlled, the effects of radon daughters will also be minimized. The legal requirements for dust control in South Africa and their implications are discussed. 1 ill

  12. 30 CFR 33.33 - Allowable limits of dust concentration.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Allowable limits of dust concentration. 33.33... MINES Test Requirements § 33.33 Allowable limits of dust concentration. (a) The concentration of dust determined by the control sample shall be subtracted from the average concentration of dust determined by the...

  13. 30 CFR 33.32 - Determination of dust concentration.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Determination of dust concentration. 33.32... MINES Test Requirements § 33.32 Determination of dust concentration. (a) Concentrations of airborne dust... microscopic technique shall be employed in determining concentrations of dust in terms of millions of...

  14. Dust storm detection using random forests and physical-based ...

    Indian Academy of Sciences (India)

    arid areas of the Middle. East. Due to the influences of dust aerosols on climate and human daily activities, dust detection plays a crucial role in environmental and climatic studies. Detection of dust storms is critical to accurately under- stand dust ...

  15. Dust analysis on board the Destiny+ mission to 3200 Phaethon

    Science.gov (United States)

    Krüger, H.; Kobayashi, M.; Arai, T.; Srama, R.; Sarli, B. V.; Kimura, H.; Moragas-Klostermeyer, G.; Soja, R.; Altobelli, N.; Grün, E.

    2017-09-01

    The Japanese Destiny+ spacecraft will be launched to the active asteroid 3200 Phaethon in 2022. Among the proposed core payload is an in-situ dust instrument based on the Cassini Cosmic Dust Analyzer. We use the ESA Interplanetary Meteoroid Engineering Model (IMEM), to study detection conditions and fluences of interplanetary and interstellar dust with a dust analyzer on board Destiny+.

  16. Nonplanar electrostatic shock waves in an opposite polarity dust ...

    Indian Academy of Sciences (India)

    M Amina

    2017-05-30

    May 30, 2017 ... clouds, interstellar media, and nebula [1–3], dusty plasma has become a very interesting field of study. Sev- eral processes are responsible for charging of dust grains. [4,5]. The charge of the dust grains highly depends on the size of the dust surface; larger dust grains are found to be negatively charged ...

  17. Effect of nonthermal ion distribution and dust temperature on ...

    Indian Academy of Sciences (India)

    the investigation of nonlinear dust acoustic waves in an unmagnetized dusty plasma. Sagdeev pseu- dopotential ... Keywords. Solitons; dust acoustic wave; Sagdeev potential; dusty plasma; nonthermal ion. PACS No. 52.25. 1. .... present analysis is that the dust charge is assumed to be constant. However if variable dust.

  18. Respirable quartz hazard associated with coal mine roof bolter dust

    International Nuclear Information System (INIS)

    Joy, G.J.; Beck, T.W.; Listak, J.M.

    2010-01-01

    Pneumoconiosis has been reported to be increasing among underground coal miners in the Southern Appalachian Region. The National Institute for Occupational Safety and Health conducted a study to examine the particle size distribution and quartz content of dust generated by the installation of roof bolts in mines. Forty-six bulk samples of roof bolting machine pre-cleaner cyclone dump dust and collector box dust were collected from 26 underground coal mines. Real-time and integrated airborne respirable dust concentrations were measured on 3 mining sections in 2 mines. The real-time airborne dust concentrations profiles were examined to identify any concentration changes that might be associated with pre-cleaner cyclone dust discharge events. The study showed that bolter dust is a potential inhalation hazard due to the fraction of dust less than 10 μm in size, and the quartz content of the dust. The pre-cleaner cyclone dust was significantly larger than the collector box dust, indicating that the pre-cleaner functioned properly in removing the larger dust size fraction from the airstream. However, the pre-cleaner dust still contained a substantial amount of respirable dust. It was concluded that in order to maintain the effectiveness of a roof bolter dust collector, periodic removal of dust is required. Appropriate work procedures and equipment are necessary to minimize exposure during this cleaning task. 13 refs., 3 tabs., 2 figs.

  19. Dust acoustic shock wave generation due to dust charge variation in ...

    Indian Academy of Sciences (India)

    pp. 1197–1201. Dust acoustic shock wave generation due to dust charge ... to generation of shock wave in the dusty plasma described as collisionless shock wave. ... Φ -(δ -1)(1+∆Qd)(1+∆Nd). ] (7) while the dust charging equation in the wave frame is d∆Qd dζ. =(1+∆Nd). µ. [ exp(Φ-z∆Qd)-exp. (-Φ σ. )( 1+ z σ +z. ∆Qd. )] σd =.

  20. The physics of wind-blown sand and dust.

    Science.gov (United States)

    Kok, Jasper F; Parteli, Eric J R; Michaels, Timothy I; Karam, Diana Bou

    2012-10-01

    The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This paper presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices. We also discuss the physics of wind-blown sand and dune formation on Venus and Titan.

  1. The physics of wind-blown sand and dust

    OpenAIRE

    Kok, Jasper F.; Parteli, Eric J. R.; Michaels, Timothy I.; Karam, Diana Bou

    2012-01-01

    The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This article presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devil...

  2. Lunar Dust Analysis Package - LDAP

    Science.gov (United States)

    Chalkley, S. A.; Richter, L.; Goepel, M.; Sovago, M.; Pike, W. T.; Yang, S.; Rodenburg, J.; Claus, D.

    2012-09-01

    The Lunar Dust Analysis package (L-DAP) is a suite of payloads which have been designed to operate in synergy with each other at the Lunar Surface. The benefits of combining these payloads in a single package allow very precise measurements of a particular regolith sample. At the same time the integration allows mass savings since common resources are shared and this also means that interfaces with the Lander are simplified significantly leading to benefits of integration and development of the overall mission. Lunar Dust represents a real hazard for lunar exploration due to its invasive, fine microscopic structure and toxic properties. However it is also valuable resource which could be exploited for future exploration if the characteristics and chemical composition is well known. Scientifically, the regolith provides an insight into the moon formation process and there are areas on the Moon which have never been ex-plored before. For example the Lunar South Pole Aitken Basin is the oldest and largest on the moon, providing excavated deep crust which has not been found on the previous lunar landing missions. The SEA-led team has been designing a compact package, known as LDAP, which will provide key data on the lunar dust properties. The intention is for this package to be part of the payload suite deployed on the ESA Lunar Lander Mission in 2018. The LDAP has a centralised power and data electronics, including front end electronics for the detectors as well as sample handling subsystem for the following set of internal instruments : • Optical Microscope - with a 1μm resolution to provide context of the regolith samples • Raman and LIBS spectrographic instrumentation providing quantification of mineral and elemental composition information of the soil at close to grain scale. This includes the capability to detect (and measure abundance of) crystalline and adsorbed volatile phases, from their Raman signature. The LIBS equipment will also allow chemical

  3. Automatic detection of typical dust devils from Mars landscape images

    Science.gov (United States)

    Ogohara, Kazunori; Watanabe, Takeru; Okumura, Susumu; Hatanaka, Yuji

    2018-02-01

    This paper presents an improved algorithm for automatic detection of Martian dust devils that successfully extracts tiny bright dust devils and obscured large dust devils from two subtracted landscape images. These dust devils are frequently observed using visible cameras onboard landers or rovers. Nevertheless, previous research on automated detection of dust devils has not focused on these common types of dust devils, but on dust devils that appear on images to be irregularly bright and large. In this study, we detect these common dust devils automatically using two kinds of parameter sets for thresholding when binarizing subtracted images. We automatically extract dust devils from 266 images taken by the Spirit rover to evaluate our algorithm. Taking dust devils detected by visual inspection to be ground truth, the precision, recall and F-measure values are 0.77, 0.86, and 0.81, respectively.

  4. Mechanical intervention for reducing dust concentration in traditional rice mills.

    Science.gov (United States)

    Pranav, Prabhanjan K; Biswas, Mrinmoy

    2016-08-05

    A huge number of workers are employed in traditional rice mills where they are potentially exposed to dust. In this study a dust collection system was developed to capture the airborne dust in the rice mill. The feeding and sieving section of the mill was identified as major dust creating zone. The dust was captured by creating suitable air stream at feeding and sieving sections of the mill and collected in cyclone dust collector. The air stream was created by blower which was selected on the basis to get minimum air speed of 0.5 m/s in the working zones of workers. It was observed that the developed system is successfully collects the significant amount of dust and able to reduce the dust concentration up to 58%. Further, the respirable dust concentration reduced to below 5 mg/m(3) throughout the mill which is within the recommended limit of dust exposure.

  5. Mineralogy of Interplanetary Dust Particles from the Comet Giacobini-Zinner Dust Stream Collections

    Science.gov (United States)

    Nakamura-Messenger, K.; Messenger, S.; Westphal, A. J.; Palma, R. L.

    2015-01-01

    The Draconoid meteor shower, originating from comet 21P/Giacobini-Zinner, is a low-velocity Earth-crossing dust stream that had a peak anticipated flux on Oct. 8, 2012. In response to this prediction, NASA performed dedicated stratospheric dust collections to target interplanetary dust particles (IDPs) from this comet stream on Oct 15-17, 2012 [3]. Twelve dust particles from this targeted collection were allocated to our coordinated analysis team for studies of noble gas (Univ. Minnesota, Minnesota State Univ.), SXRF and Fe-XANES (SSL Berkeley) and mineralogy/isotopes (JSC). Here we report a mineralogical study of 3 IDPs from the Draconoid collection..

  6. Applications of Electrified Dust and Dust Devil Electrodynamics to Martian Atmospheric Electricity

    Science.gov (United States)

    Harrison, R. G.; Barth, E.; Esposito, F.; Merrison, J.; Montmessin, F.; Aplin, K. L.; Borlina, C.; Berthelier, J J.; Deprez, G.; Farrell, William M.; hide

    2016-01-01

    Atmospheric transport and suspension of dust frequently brings electrification, which may be substantial. Electric fields of 10 kV m(exp. -1) to 100 kV m(exp. -1) have been observed at the surface beneath suspended dust in the terrestrial atmosphere, and some electrification has been observed to persist in dust at levels to 5 km, as well as in volcanic plumes. The interaction between individual particles which causes the electrification is incompletely understood, and multiple processes are thought to be acting. A variation in particle charge with particle size, and the effect of gravitational separation explains to, some extent, the charge structures observed in terrestrial dust storms. More extensive flow-based modelling demonstrates that bulk electric fields in excess of 10 kV m(exp. -1) can be obtained rapidly (in less than 10 s) from rotating dust systems (dust devils) and that terrestrial breakdown fields can be obtained. Modelled profiles of electrical conductivity in the Martian atmosphere suggest the possibility of dust electrification, and dust devils have been suggested as a mechanism of charge separation able to maintain current flow between one region of the atmosphere and another, through a global circuit. Fundamental new understanding of Martian atmospheric electricity will result from the ExoMars mission, which carries the DREAMS (Dust characterization, Risk Assessment, and Environment Analyser on the Martian Surface) MicroARES (Atmospheric Radiation and Electricity Sensor) Instrumentation to Mars in 2016 for the first in situ electrical measurements.

  7. Study on the alternative mitigation of cement dust spread by capturing the dust with fogging method

    Science.gov (United States)

    Purwanta, Jaka; Marnoto, Tjukup; Setyono, Prabang; Handono Ramelan, Ari

    2017-12-01

    The existence of a cement plant impact the lives of people around the factory site. For example the air quality, which is polluted by dust. Cement plant has made various efforts to mitigate the generated dust, but there are still alot of dust fly inground either from the cement factory chimneys or transportation. The purpose of this study was to conduct a review of alternative mitigation of the spread of dust around the cement plant. This study uses research methods such as collecting secondary data which includes data of rain density, the average rains duration, wind speed and direction as well as data of dust intensity quality around PT. Semen Gresik (Persero) Tbk.Tuban plant. A soft Wind rose file is used To determine the wind direction propensity models. The impact on the spread of dust into the environment is determined using secondary data monitoring air quality. Results of the study is that the mitigation of dust around the cement plant is influenced by natural factors, such as the tendency of wind direction, rain fall and rainy days, and the rate of dust emission from the chimney. The alternative means proposed is an environmental friendly fogging dust catcher.

  8. Stochastic Models of Molecule Formation on Dust

    Science.gov (United States)

    Charnley, Steven; Wirstroem, Eva

    2011-01-01

    We will present new theoretical models for the formation of molecules on dust. The growth of ice mantles and their layered structure is accounted for and compared directly to observations through simulation of the expected ice absorption spectra

  9. Nanotube Electrodes for Dust Mitigation, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Dust mitigation is critical to the survivability of vehicle and infrastructure components and systems and to the safety of astronauts during EVAs and planetary...

  10. Spherically symmetric inhomogeneous dust collapse in higher ...

    Indian Academy of Sciences (India)

    We consider a collapsing spherically symmetric inhomogeneous dust cloud in higher dimensional space-time. We show that the central singularity of collapse can be a strong curvature or a weak curvature naked singularity depending on the initial density distribution.

  11. Surface System Dust Mitigation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed effort will perform a detailed examination of dust mitigation and tolerance strategies for connections and mechanisms to be employed on the lunar...

  12. He Puff System For Dust Detector Upgrade

    International Nuclear Information System (INIS)

    Rais, B.; Skinner, C.H.; Roquemore, A.L.

    2010-01-01

    Local detection of surface dust is needed for the safe operation of next-step magnetic fusion devices such as ITER. An electrostatic dust detector, based on a 5 cm x 5 cm grid of interlocking circuit traces biased to 50 V, has been developed to detect dust on remote surfaces and was successfully tested for the first time on the National Spherical Torus Experiment (NSTX). We report on a helium puff system that clears residual dust from this detector and any incident debris or fibers that might cause a permanent short circuit. The entire surface of the detector was cleared of carbon particles by two consecutive helium puffs delivered by three nozzles of 0.45 mm inside diameter. The optimal configuration was found to be with the nozzles at an angle of 30o with respect to the surface of the detector and a helium backing pressure of 6 bar.

  13. Solar-Panel Dust Accumulation and Cleanings

    Science.gov (United States)

    2005-01-01

    Air-fall dust accumulates on the solar panels of NASA's Mars Exploration Rovers, reducing the amount of sunlight reaching the solar arrays. Pre-launch models predicted steady dust accumulation. However, the rovers have been blessed with occasional wind events that clear significant amounts of dust from the solar panels. This graph shows the effects of those panel-cleaning events on the amount of electricity generated by Spirit's solar panels. The horizontal scale is the number of Martian days (sols) after Spirit's Jan. 4, 2005, (Universal Time) landing on Mars. The vertical scale indicates output from the rover's solar panels as a fraction of the amount produced when the clean panels first opened. Note that the gradual declines are interrupted by occasional sharp increases, such as a dust-cleaning event on sol 420.

  14. Coir dust reinforced recycled polypropylene composites

    International Nuclear Information System (INIS)

    Santos, Bianca B. dos; Costa, Marysilvia F. da; Thire, Rossana M. da S.M.

    2015-01-01

    The environmental impacts caused by disposed plastics encourage the search for new alternatives. Recycling polymers leads to the degradation of their mechanical properties, which can be modified by the addition of fillers. In this paper, recycled polypropylene from plastic cups with 2%, 5% and 10% of coir dust were produced with and without the addition of additives. These composites were characterized by tensile tests, X-ray diffraction, differential scanning calorimetry and scanning electron microscopy on the fracture surface. It was verified the effectiveness of the addition of coir dust in improving the elasticity modulus of recycled polypropylene besides the effectiveness of additives used in promoting the adhesion of the powder to the matrix. However, higher levels of coir dust caused the appearance of air bubbles inside the material, which contributed to its embrittlement. The addition of coir dust promoted a decrease in the degree of polypropylene crystallinity. (author)

  15. The composition of circumstellar and interstellar dust

    NARCIS (Netherlands)

    Tielens, AGGM; Woodward, CE; Biscay, MD; Shull, JM

    2001-01-01

    A large number of solid dust components have been identified through analysis of stardust recovered from meteorites, and analysis of IR observations of circumstellar shells and the interstellar medium. These include graphite, hydrogenated amorphous carbon, diamond, PAHs, silicon-, iron-, and

  16. Blowing Dust Away With Electrostatic Wind

    Science.gov (United States)

    Utter, M. G.

    1984-01-01

    Ionized air molecules drive away contaminants. Electrostatic wind prevents dust buildup and subsequent electrical breakdown in powerlines, transformers, switchgears, Van de Graaff generators, electrostatic precipitators, and other high-voltage equipment. Makes periodic cleaning or airblasting unnecessary.

  17. High-Fidelity Lunar Dust Simulant Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The severity of the lunar dust problems encountered during the Apollo missions were consistently underestimated by ground tests, illustrating the need to develop...

  18. Regenerable Lunar Airborne Dust Filter, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Effective methods are needed to control pervasive Lunar Dust within spacecraft and surface habitations. Once inside, airborne transmission is the primary mode of...

  19. Ephemeral lakes and desert dust sources

    Science.gov (United States)

    Mahowald, Natalie M.; Bryant, Robert G.; del Corral, John; Steinberger, Linda

    2003-01-01

    The processes that determine which areas are strong sources of mineral aerosols are not well known. In this study we consider the role of ephemeral lakes in modulating emissions of atmospheric mineral aerosols. We focus on two ephemeral lake regions that have been identified as source regions: the zone of Chotts in Tunisia and Algeria, and Etosha Pan in Namibia. Comparisons of satellite retrieved inundation data and the TOMS absorbing aerosol index suggest that during some periods of inundation, desert dust loadings are reduced. There is some indication that after flooded areas have dried there is increased dust loading. However, the role of the inundated ephemeral lake compared with nearby regions in modulating desert dust sources is unclear, in addition, problems with interpreting the TOMS AI make conclusions difficult. More research is required to understand the small-scale sources of atmospheric desert dust in dry, unvegetated, topographic lows.

  20. Nanotube Electrodes for Dust Mitigation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Dust mitigation is critical to the survivability of vehicle and infrastructure components and systems and to the safety of astronauts during EVAs and planetary...

  1. The Marriage of Gas and Dust

    Science.gov (United States)

    Price, D. J.; Laibe, G.

    2015-10-01

    Dust-gas mixtures are the simplest example of a two fluid mixture. We show that when simulating such mixtures with particles or with particles coupled to grids a problem arises due to the need to resolve a very small length scale when the coupling is strong. Since this is occurs in the limit when the fluids are well coupled, we show how the dust-gas equations can be reformulated to describe a single fluid mixture. The equations are similar to the usual fluid equations supplemented by a diffusion equation for the dust-to-gas ratio or alternatively the dust fraction. This solves a number of numerical problems as well as making the physics clear.

  2. A GCM study of the response of the atmospheric water cycle of West Africa and the Atlantic to Saharan dust radiative forcing

    Directory of Open Access Journals (Sweden)

    K. M. Lau

    2009-10-01

    Full Text Available The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM, coupled to a mixed layer ocean. We find evidence of an "elevated heat pump" (EHP mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summer, as a result of large-scale atmospheric feedback triggered by absorbing dust aerosols, rainfall and cloudiness are enhanced over the West Africa/Eastern Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while longwave has the opposite response. The elevated dust layer warms the air over West Africa and the eastern Atlantic. As the warm air rises, it spawns a large-scale onshore flow carrying the moist air from the eastern Atlantic and the Gulf of Guinea. The onshore flow in turn enhances the deep convection over West Africa land, and the eastern Atlantic. The condensation heating associated with the ensuing deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in a northward shift of the West Africa precipitation over land, increased low-level westerly flow over West Africa at the southern edge of the dust layer, and a near surface westerly jet underneath the dust layer over the Sahara. The dust radiative forcing also leads to significant changes in surface energy fluxes, resulting in cooling of the West African land and the eastern Atlantic, and warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single

  3. A GCM Study of Responses of the Atmospheric Water Cycle of West Africa and the Atlantic to Saharan Dust Radiative Forcing

    Science.gov (United States)

    Lau, K. M.; Kim, K. M.; Sud, Y. C.; Walker, G. K.

    2009-01-01

    The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence of an "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summerr, as a result of large-scale atmospheric feedback triggered by absorbing dust aerosols, rainfall and cloudiness are ehanIed over the West Africa/Eastern Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while longwave has the opposite response. The elevated dust layer warms the air over West Africa and the eastern Atlantic. As the warm air rises, it spawns a large-scale onshore flow carrying the moist air from the eastern Atlantic and the Gulf of Guinea. The onshore flow in turn enhances the deep convection over West Africa land, and the eastern Atlantic. The condensation heating associated with the ensuing deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in a northward shift of the West Africa precipitation over land, increased low-level westerlies flow over West Africa at the southern edge of the dust layer, and a near surface westerly jet underneath the dust layer overr the Sahara. The dust radiative forcing also leads to significant changes in surface energy fluxes, resulting in cooling of the West African land and the eastern Atlantic, and warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at0

  4. Investigations of Wind/WAVES Dust Impacts

    Science.gov (United States)

    St Cyr, O. C.; Wilson, L. B., III; Rockcliffe, K.; Mills, A.; Nieves-Chinchilla, T.; Adrian, M. L.; Malaspina, D.

    2017-12-01

    The Wind spacecraft launched in November 1994 with a primary goal to observe and understand the interaction between the solar wind and Earth's magnetosphere. The waveform capture detector, TDS, of the radio and plasma wave investigation, WAVES [Bougeret et al., 1995], onboard Wind incidentally detected micron-sized dust as electric field pulses from the recollection of the impact plasma clouds (an unintended objective). TDS has detected over 100,000 dust impacts spanning almost two solar cycles; a dataset of these impacts has been created and was described in Malaspina & Wilson [2016]. The spacecraft continues to collect data about plasma, energetic particles, and interplanetary dust impacts. Here we report on two investigations recently conducted on the Wind/WAVES TDS database of dust impacts. One possible source of dust particles is the annually-recurring meteor showers. Using the nine major showers defined by the American Meteor Society, we compared dust count rates before, during, and after the peak of the showers using averaging windows of varying duration. However, we found no statistically significant change in the dust count rates due to major meteor showers. This appears to be an expected result since smaller grains, like the micron particles that Wind is sensitive to, are affected by electromagnetic interactions and Poynting-Robertson drag, and so are scattered away from their initial orbits. Larger grains tend to be more gravitationally dominated and stay on the initial trajectory of the parent body so that only the largest dust grains (those that create streaks as they burn up in the atmosphere) are left in the orbit of the parent body. Ragot and Kahler [2003] predicted that coronal mass ejections (CMEs) near the Sun could effectively scatter dust grains of comparable size to those observed by Wind. Thus, we examined the dust count rates immediately before, during, and after the passage of the 350 interplanetary CMEs observed by Wind over its 20+ year

  5. Migration of Interplanetary Dust and Comets

    Science.gov (United States)

    Ipatov, S. I.; Mather, J. C.

    Our studies of migration of interplanetary dust and comets were based on the results of integration of the orbital evolution of 15,000 dust particles and 30,000 Jupiter-family comets (JFCs) [1-3]. For asteroidal and cometary particles, the values of the ratio β between the radiation pressure force and the gravitational force varied from 1000 and 1 microns. The probability of a collision of a dust particle started from an asteroid or JFC with the Earth during a lifetime of the particle was maximum at diameter d ˜100 microns. For particles started from asteroids and comet 10P, this maximum probability was ˜0.01. Different studies of migration of dust particles and small bodies testify that the fraction of cometary dust particles of the overall dust population inside Saturn's orbit is considerable and can be dominant: (1) Cometary dust particles produced both inside and outside Jupiter's orbit are needed to explain the observed constant number density of dust particles at 3-18 AU. The number density of migrating trans-Neptunian particles near Jupiter's orbit is smaller by a factor of several than that beyond Saturn's orbit. Only a small fraction of asteroidal particles can get outside Jupiter's orbit. (2) Some (less than 0.1%) JFCs can reach typical near-Earth object orbits and remain there for millions of years. Dynamical lifetimes of most of the former JFCs that have typical near-Earth object orbits are about 106 -109 yr, so during most of these times they were extinct comets. Such former comets could disintegrate and produce a lot of mini-comets and dust. (3) Comparison of the velocities of zodiacal dust particles (velocities of MgI line) based on the distributions of particles over their orbital elements obtained in our runs [3-4] with the velocities obtained at the WHAM observations shows that only asteroidal dust particles cannot explain these observations, and particles produced by comets, including high-eccentricity comets, are needed for such explanation

  6. The Dust Accelerator Facility at CCLDAS

    Science.gov (United States)

    Shu, A. J.; Collette, A.; Drake, K.; Gruen, E.; Horanyi, M.; Leblanc, S.; Munsat, T.; Northway, P.; Robertson, S. H.; Srama, R.; Sternovsky, Z.; Thomas, E.; Wagner, M.; Colorado CenterLunar Dust; Atmospheric Studies

    2010-12-01

    At the Colorado Center for Lunar Dust and Atmospheric Science (CCLDAS) we are in the process of assembling a 3MV macroscopic (~1um) dust particle accelerator. The acceleration unit is being made by the National Electrostatics Corporation (NEC). The accelerator consists of a pelletron generator and potential rings encased in an enclosure held at 6 atm of SF6. A pulsed dust source is used to inject particles into the accelerator. Here we describe advancements in dust accelerator technology at CCLDAS to allow more functionality and ease of use, focusing primarily on dust source control, and the capability to select a precise range in dust mass and velocity. Previously, the dust source was controlled by long plastic rods turning potentiometers inside the SF6 environment providing little to no feedback and repeatability. We describe a fiber optic control system that allows full control of the pulse characteristics being sent to the dust source using a LabVIEW control program to increase usability. An electrostatic Einzel lens is being designed using the ion-optics code SIMION to determine the properties of the electrodes needed for the optimum focusing of the dust beam. Our simulations studies indicate that the dust beam can be directed into a 0.5mm diameter spot. Our planned experiments require a high degree of control over particles size, speed, charge and other characteristics. In order to ensure that only particles of the desired characteristics are allowed to pass into the target chamber, two deflection plates are used to eliminate unwanted particles from the beam. Further simulations are being done to determine the possibility of bending the beamline to allow active selection of particles. The current design of the selection unit uses nuclear accelerator techniques to determine the velocity and charge of each particle and digital timing and logic to choose particles that will be allowed to pass. This requires a high signal to noise ratio due to the need for a well

  7. Ecological relationships between xerophilic fungi and house-dust mites (Acarida: Pyroglyphidae).

    Science.gov (United States)

    Lustgraaf, B V D

    1978-01-01

    At. 75 and 80% relative humidity (RH), on a wheat germ flake medium, Aspergillus penicilloides grew abundantly and suppressed the population growth of Dermatophagoides pteronyssiunus. At 71% RH, A. penicilloides grew moderately and was only antagonistic to D. pteronyssinus when the fungus was previously incubated on the medium.On a human dander medium and on mattress dust, A. penicilloides grew moderately at 71% and 75% RH and stimulated the development of D. pteronyssinus populations. Also a moderate growth of Eurotium repens on human dander positively influenced D. pteronyssinus. Wallemia sebi and Penicillium brevicompactum grew slightly or did not grow at all at 75% RH. No effect was observed on D. pteronyssinus.It appears that xerophilic fungi may stimulate, and occasionally may reduce, the growth of house-dust mite populations in the natural environment.

  8. Allergy to house dust mites and asthma.

    Science.gov (United States)

    Milián, Evelyn; Díaz, Ana María

    2004-03-01

    House dust mites have been shown to be important sources of indoor allergens associated with asthma and other allergic conditions. Asthma is a chronic respiratory disease that affects millions of people worldwide, and numerous scientific studies have shown that the prevalence of asthma is increasing. The most common dust mite species around the world include Dermatophagoides pteronyssinus (Dp), Dermatophagoides farinae (Df), Euroglyphus maynei (Em) and Blomia tropicalis (Bt). Over the past three decades, many important allergens from these species have been identified and characterized at the molecular level. The biological function of several house dust mite allergens has been elucidated, with many of them showing enzymatic activity. However, Bt allergens remain the least studied, even though this mite is very common in tropical and subtropical regions of the world, including Puerto Rico. Therefore, it is very important to include Bt in diagnostic and therapeutic strategies for house dust mite induced allergy and asthma, particularly in areas where Bt exposure and sensitization is high. Recombinant DNA technology, as well as other molecular biology and immunological techniques, have played a fundamental role in advances towards a better understanding of the biology of house dust mites and their role in allergic diseases. This kind of study also contributes to the understanding of the complex immunologic mechanisms involved in allergic reactions. The development of effective diagnostic and therapeutic approaches depends on the continuity of research of house dust mite allergens. The objectives of this review are to describe the most important aspects of house dust mite allergy and to acquaint the scientific community with the latest findings pertaining to house dust mite allergens, particularly those derived from Bt.

  9. 2015 Dust Risk Standing Review Panel

    Science.gov (United States)

    Steinberg, Susan

    2015-01-01

    The 2015 Dust Risk Standing Review Panel (SRP) participated in a WebEx/teleconference with members of the Space Human Factors and Habitability (SHFH) Element, representatives from the Human Research Program (HRP), NASA Headquarters, and the NASA Research Education and Support Services on November 12, 2015. The SRP reviewed the updated Evidence Report for The Risk of Adverse Health and Performance Effects of Celestial Dust Exposure, as well as the Research Plan for this Risk.

  10. Dust trajectory sensor: accuracy and data analysis.

    Science.gov (United States)

    Xie, J; Sternovsky, Z; Grün, E; Auer, S; Duncan, N; Drake, K; Le, H; Horanyi, M; Srama, R

    2011-10-01

    The Dust Trajectory Sensor (DTS) instrument is developed for the measurement of the velocity vector of cosmic dust particles. The trajectory information is imperative in determining the particles' origin and distinguishing dust particles from different sources. The velocity vector also reveals information on the history of interaction between the charged dust particle and the magnetospheric or interplanetary space environment. The DTS operational principle is based on measuring the induced charge from the dust on an array of wire electrodes. In recent work, the DTS geometry has been optimized [S. Auer, E. Grün, S. Kempf, R. Srama, A. Srowig, Z. Sternovsky, and V Tschernjawski, Rev. Sci. Instrum. 79, 084501 (2008)] and a method of triggering was developed [S. Auer, G. Lawrence, E. Grün, H. Henkel, S. Kempf, R. Srama, and Z. Sternovsky, Nucl. Instrum. Methods Phys. Res. A 622, 74 (2010)]. This article presents the method of analyzing the DTS data and results from a parametric study on the accuracy of the measurements. A laboratory version of the DTS has been constructed and tested with particles in the velocity range of 2-5 km/s using the Heidelberg dust accelerator facility. Both the numerical study and the analyzed experimental data show that the accuracy of the DTS instrument is better than about 1% in velocity and 1° in direction.

  11. Modeling Respiratory Toxicity of Authentic Lunar Dust

    Science.gov (United States)

    Santana, Patricia A.; James, John T.; Lam, Chiu-Wing

    2010-01-01

    The lunar expeditions of the Apollo operations from the 60 s and early 70 s have generated awareness about lunar dust exposures and their implication towards future lunar explorations. Critical analyses on the reports from the Apollo crew members suggest that lunar dust is a mild respiratory and ocular irritant. Currently, NASA s space toxicology group is functioning with the Lunar Airborne Dust Toxicity Assessment Group (LADTAG) and the National Institute for Occupational Safety and Health (NIOSH) to investigate and examine toxic effects to the respiratory system of rats in order to establish permissible exposure levels (PELs) for human exposure to lunar dust. In collaboration with the space toxicology group, LADTAG and NIOSH the goal of the present research is to analyze dose-response curves from rat exposures seven and twenty-eight days after intrapharyngeal instillations, and model the response using BenchMark Dose Software (BMDS) from the Environmental Protection Agency (EPA). Via this analysis, the relative toxicities of three types of Apollo 14 lunar dust samples and two control dust samples, titanium dioxide (TiO2) and quartz will be determined. This will be executed for several toxicity endpoints such as cell counts and biochemical markers in bronchoaveolar lavage fluid (BALF) harvested from the rats.

  12. The Dust Management Project: Final Report

    Science.gov (United States)

    Hyatt, Mark J.; Straka, Sharon

    2011-01-01

    A return to the Moon to extend human presence, pursue scientific activities, use the Moon to prepare for future human missions to Mars, and expand Earth s economic sphere, will require investment in developing new technologies and capabilities to achieve affordable and sustainable human exploration. From the operational experience gained and lessons learned during the Apollo missions, conducting longterm operations in the lunar environment will be a particular challenge, given the difficulties presented by the unique physical properties and other characteristics of lunar regolith, including dust. The Apollo missions and other lunar explorations have identified significant lunar dust-related problems that will challenge future mission success. Comprised of regolith particles ranging in size from tens of nanometers to microns, lunar dust is a manifestation of the complex interaction of the lunar soil with multiple mechanical, electrical, and gravitational effects. The environmental and anthropogenic factors effecting the perturbation, transport, and deposition of lunar dust must be studied in order to mitigate it s potentially harmful effects on exploration systems and human explorers. The Dust Management Project (DMP) is tasked with the evaluation of lunar dust effects, assessment of the resulting risks, and development of mitigation and management strategies and technologies related to Exploration Systems architectures. To this end, the DMP supports the overall goal of the Exploration Technology Development Program (ETDP) of addressing the relevant high priority technology needs of multiple elements within the Constellation Program (CxP) and sister ETDP projects. Project scope, approach, accomplishments, summary of deliverables, and lessons learned are presented.

  13. Inhalation of road dust by human subjects.

    Science.gov (United States)

    Takishima, T; Nakamura, M; Sasaki, M; Miyano, M; Yamaya, M; Sasaki, H

    1987-11-01

    We measured pneumomagnetic field strength (PMFS) in 42 healthy control subjects living in districts of Northern Japan with low levels of road dust pollution and in 39 healthy subjects living in areas with high levels of road dust pollution. Suspended road dust produced by studded tires increases from 30 micrograms/m3 during the summer season to levels as high as 400 micrograms/m3 during the snow season in the downtown areas of Sendai, Japan. Road dust retained in the lungs, containing 3% iron, was magnetized from the surface of the chest wall, and PMFS was measured. Three to 5 sequential PMFS measurements were made in each subject in March and October of 1984 and 1985, and in March 1986. The PMFS in control subjects in March 1984 was 37 +/- 14 pico-Tesla (mean +/- SD) and did not significantly differ from the PMFS in October 1984 or that in March 1985. In March 1984, the PMFS of the subjects in highly polluted areas was 95 +/- 100 pico-Tesla (mean +/- SD) and was significantly higher than that of control subjects (p less than 0.01) and subsequently decreased in March 1985 and in March 1986, corresponding to a decrease in suspended road dust brought about by a campaign to eliminate the use of studded tires. Our findings suggest that some road dust caused by studded tires is retained in the lungs.

  14. Volcanic loading: The dust veil index

    Energy Technology Data Exchange (ETDEWEB)

    Lamb, H.H. [Univ. of East Anglia, Norwich (United Kingdom). Climatic Research Unit

    1985-09-01

    Dust ejected into the high atmosphere during explosive volcanic eruptions has been considered as a possible cause for climatic change. Dust veils created by volcanic eruptions can reduce the amount of light reaching the Earth`s surface and can cause reductions in surface temperatures. These climatic effects can be seen for several years following some eruptions and the magnitude and duration of the effects depend largely on the density or amount of tephra (i.e. dust) ejected, the latitude of injection, and atmospheric circulation patterns. Lamb (1970) formulated the Dust Veil Index (DVI) in an attempt to quantify the impact on the Earth`s energy balance of changes in atmospheric composition due to explosive volcanic eruptions. The DVI is a numerical index that quantifies the impact on the Earth`s energy balance of changes in atmospheric composition due to explosive volcanic eruptions. The DVI is a numerical index that quantifies the impact of a particular volcanic eruptions release of dust and aerosols over the years following the event. The DVI for any volcanic eruptions are available and have been used in estimating Lamb`s dust veil indices.

  15. Looking for Dust-Scattering Light Echoes

    Science.gov (United States)

    Mills, Brianna; Heinz, Sebastian; Corrales, Lia

    2018-01-01

    Galactic X-ray transient sources such as neutron stars or black holes sometimes undergo an outburst in X-rays. Ring structures have been observed around three such sources, produced by the X-ray photons being scattered by interstellar dust grains along our line of sight. These dust-scattering light echoes have proven to be a useful tool for measuring and constraining Galactic distances, mapping the dust structure of the Milky Way, and determining the dust composition in the clouds producing the echo. Detectable light echoes require a sufficient quantity of dust along our line of sight, as well as bright, short-lived Galactic X-ray flares. Using data from the Monitor of All-Sky X-ray Image (MAXI) on-board the International Space Station, we ran a peak finding algorithm in Python to look for characteristic flare events. Each flare was characterized by its fluence, the integrated flux of the flare over time. We measured the distribution of flare fluences to show how many observably bright flares were recorded by MAXI. This work provides a parent set for dust echo searches in archival X-ray data and will inform observing strategies with current and future X-ray missions such as Athena and Lynx.

  16. Electronic design of air dust concentration gauge

    International Nuclear Information System (INIS)

    Machaj, B.; Strzalkowski, J.; Krawczynska, B.

    1993-01-01

    A new version of isotope dust concentration gauge for monitoring airborne dust pollution of air employs a ready made personal computer as the control and processing unit in the gauge instead of specialized electronics. That solution of the gauge reduces the needed specialized electronics to a simple computer interface coupling the computer to the measuring head. This also reduced electronics of the measuring head itself, i.e. GM detector circuit, power supplies and electronic circuits to switch on/off driving motors. The functioning and operation of the gauge is controlled by the computer program that can be easily modified if needed. The computer program for the gauge enables automatic measurements of dust concentration. Up to fifty measuring cycles can be easily programmed for a day. The results of measurements are presented in the form of data collection, diagram of dust concentration distribution during one day, diagram of dust distribution during 30 successive days or diagram of average dust concentration distribution during a day which may be computed by combining data of the selected number of measurements. Recalibration of the gauge and checking up of the gauge are also carried out under the program control. (author). 6 refs, 9 figs

  17. DIFFUSE EXTRAPLANAR DUST IN NGC 891

    Energy Technology Data Exchange (ETDEWEB)

    Seon, Kwang-il; Shinn, Jong-ho; Kim, Il-joong [Korea Astronomy and Space Science Institute, Daejeon, 305-348 (Korea, Republic of); Witt, Adolf N., E-mail: kiseon@kasi.re.kr [Ritter Astrophysical Research Center, University of Toledo, Toledo, OH 43606 (United States)

    2014-04-10

    We report the detection of vertically extended far-ultraviolet and near-UV emissions in an edge-on spiral galaxy NGC 891, which we interpret as being due to dust-scattered starlight. Three-dimensional radiative transfer models are used to investigate the content of the extraplanar dust that is required to explain the UV emission. The UV halos are well reproduced by a radiative transfer model with two exponential dust disks, one with a scale height of ≈0.2-0.25 kpc and the other with a scale height of ≈1.2-2.0 kpc. The central face-on optical depth of the geometrically thick disk is found to be τ{sub B}{sup thick}≈0.3--0.5 at the B band. The results indicate that the dust mass at |z| > 2 kpc is ≈3%-5% of the total dust mass, which is in good accordance with the recent Herschel submillimeter observation. Our results, together with the recent discovery of the UV halos in other edge-on galaxies, suggest the widespread existence of a geometrically thick dust layer above the galactic plane in spirals.

  18. Dust Particle Size Distributions during Spring in Yinchuan, China

    Directory of Open Access Journals (Sweden)

    Jiangfeng Shao

    2016-01-01

    Full Text Available Dust particle size distributions in Yinchuan, China, were measured during March and April 2014, using APS-3321 sampler. The distributions were measured under different dust conditions (background, floating dust, blowing dust, and dust storm and statistical analyses were performed. The results showed that, under different dust conditions, the instantaneous number concentrations of dust particles differed widely. For example, during blowing sand and dust storm conditions, instantaneous dust particles concentrations varied substantially, while, under floating dust conditions, concentration differences were relatively small. The average dust particles size distributions were unimodal under all dust conditions, but the average surface area and mass size distributions were all bimodal. These distributions had peaks in different locations under different dust conditions. Under different dust conditions, wind speed and humidity were very important factors for particles size distributions. With increasing wind speed and decreasing humidity, fine particles were dominant in the atmosphere and the number and mass distributions of the coarse particles were indicative of long-range transport from surrounding deserts. Different dust conditions had different influences on PM1, PM2.5, and PM10 concentrations.

  19. Radiative transfer in dust clouds

    International Nuclear Information System (INIS)

    Rowan-Robinson, M.; Harris, S.

    1983-01-01

    The infrared emission has been modelled from 85 late-type M stars, essentially all such stars in the AFGL catalogue with substantial circumstellar dust shells and for which adequate observational data are currently available. The dependence of the emergent spectrum on the temperature of the stars, the condensation temperature of the grains, and the density distribution, optical depth and extent of the shell have been investigated. Consistent models for most stars have been found using dirty silicate grains, with an n(r) proportional to r - 2 density distribution and a grain melting temperature of 1000 K. Allowance has been made for the effect of molecular bands. Although these bands have a dramatic effect on the spectrum of late-type stars at visual wavelengths, there is little effect on the infrared emission from the circumstellar shell. All stars in the study except GL 915, VY CMa and NML Cyg are consistent with having spherically symmetric shells. Except for VY CMa and NML Cyg, for which other evidence suggests a disc geometry, the intensity distributions predicted by the models are consistent with interferometric measurements at infrared wavelengths. (author)

  20. Airborne dust particle counting techniques.

    Science.gov (United States)

    Sharma, S G; Prasad, B D

    2006-03-01

    The paper briefly describes an electro-optical system for counting of dust particles, which is based on the scattering phenomena. Utilizing the scattering of light by various size particles present in the environment, various particle counting techniques have been developed in order to measure the scattered intensity of light. Light scatters in all directions but much more in the so-called near forward direction 17( composite function) off axis, at 163( composite function) from the light source in the visible range. On the basis of two techniques, the right angle and forward angle scattering, opto-mechanical systems have been developed which measure scattered intensity and particulate matter. The forward scattering Nephelometer is more sensitive and therefore is more suitable for pollution monitoring than the right angle scattering Nephelometer. Whereas the right angle scattering Nephelometer has the utility in extremely low concentration in ppb level owing to the excellent light trap efficiency in comparison to forward scattering Nephelometer. In this paper measurement techniques and measurement results associated with design and development of a real time particle analyser are also discussed.

  1. Electrospray Collection of Lunar Dust

    Science.gov (United States)

    Dziekan, Michael

    2012-01-01

    A report describes ElectroSpray Ionization based Electrostatic Precipitation (ESIEP) for collecting lunar dust particles. While some HEPA filtration processes may remove a higher fraction (>99.9 percent) of the particles, the high efficiency may not be appropriate from an overall system standpoint, especially in light of the relatively large power requirement that such systems demand. The new electrospray particle capture technology is described as a variant of electrostatic precipitation that eliminates the current drawbacks of electrostatic precipitation. The new approach replaces corona prone field with a mist of highly charged micro-droplets generated by electrospray ionization (ESI) as the mechanism by which incoming particles are attracted and captured. In electrospray, a miniscule flow rate (microliters/minute) of liquid (typically water and a small amount of salt to enhance conductivity) is fed from the tip of a needle held at a high voltage potential relative to an opposite counter electrode. At sufficient field strength, a sharp liquid meniscus forms , which emits a jet of highly charged droplets that drift through the surrounding gas and are collected on the walls of a conductive tube. Particles in the gas have a high probability of contact with the droplets either by adhering to the droplets or otherwise acquiring a high level of charge, causing them to be captured on the collecting electrode as well. The spray acts as a filtration material that is continuously introduced and removed from the gas flow, and thus can never become clogged.

  2. Analysis of nickel refinery dusts.

    Science.gov (United States)

    Draper, M H; Duffus, J H; John, P; Metcalfe, L; Morgan, L; Park, M V; Weitzner, M I

    1994-06-06

    After characterization of bulk samples by inductively coupled plasma emission spectroscopic (ICP-ES) quantitative analysis and X-ray powder diffraction studies, single particle techniques using quantitative image analysis, scanning electron microscopy--energy dispersive analysis by X-ray, and finally laser beam ionization mass spectrometry analysis (LIMA) for surface analysis have been applied to historical nickel refinery dust samples from the nickel refining plant at Clydach in Wales. There were two historical samples of processed material from 1920 and 1929. These samples had a remarkably small particle size range, mean 3 microns and range, 0.75-24 microns. The most significant difference in elemental composition was the presence of 10% arsenic in the 1920 sample compared with 1% in the 1929 sample. The X-ray spectra revealed the presence of NiO in both. However, surprisingly, CuO was identified only in the 1929 sample. Of particular interest was the presence of a component, in the 1920 sample only, identified as the mineral orcelite, a copper-iron-nickel-arsenide-sulphide mineral, predominantly, Ni5-XAs2. Using the LIMA technique, it was found that in both samples, arsenic and arsenic derivative peaks are prominent, indicating the surface availability of arsenic compounds.

  3. Menstrual suppression in the adolescent.

    Science.gov (United States)

    Kantartzis, Kelly L; Sucato, Gina S

    2013-06-01

    Menstrual suppression, the use of contraceptive methods to eliminate or decrease the frequency of menses, is often prescribed for adolescents to treat menstrual disorders or to accommodate patient preference. For young women using hormonal contraceptives, there is no medical indication for menstruation to occur monthly, and various hormonal contraceptives can be used to decrease the frequency of menstruation with different side effect profiles and rates of amenorrhea. This article reviews the different modalities for menstrual suppression, common conditions in adolescents which may improve with menstrual suppression, and strategies for managing common side effects. Copyright © 2013 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

  4. 'Nuisance Dust' - a Case for Recalibration?

    Science.gov (United States)

    Datson, Hugh; Marker, Brian

    2013-04-01

    This paper considers the case for a review and recalibration of limit values and acceptability criteria for 'nuisance dust', a widely encountered but poorly defined and regulated aspect of particulate matter pollution. Specific dust fractions such as PM10 and asbestiforms are well characterised and have limit values enshrined in legislation. National, and international, limit values for acceptable concentrations of PM10 and other fractions of particulate matter have been defined and agreed. In the United Kingdom (UK), these apply to both public and workplace exposures. By contrast, there is no standard definition or universal criteria against which acceptable levels for 'nuisance dust' can be assessed. This has implications for land-use planning and resource utilisation. Without meaningful limit values, inappropriate development might take place too near to residential dwellings or land containing economically important mineral resources may be effectively sterilised. Furthermore, the expression 'nuisance dust' is unhelpful in that 'nuisance' has a specific meaning in environmental law whilst 'nuisance dust' is often taken to mean 'generally visible particulate matter'. As such, it is associated with the social and broader environmental impacts of particulate matter. PM10 concentrations are usually expressed as a mass concentration over time. These can be determined using a range of techniques. While results from different instruments are generally comparable, data obtained from alternative methods for measuring 'nuisance dust' are rarely interchangeable. In the UK, many of the methods typically used are derived from approaches developed under the HMIP (Her Majesty's Inspectorate of Pollution) regime in the 1960s onwards. Typical methods for 'nuisance dust' sampling focus on measurement of dust mass (from the weight of dust collected in an open container over time) or dust soiling (from loss of reflectance and or obscuration of a surface discoloured by dust over

  5. Environmentally dependent dust chemistry of a super Asian dust storm in March 2010: observation and simulation

    Science.gov (United States)

    Wang, Qiongzhen; Dong, Xinyi; Fu, Joshua S.; Xu, Jian; Deng, Congrui; Jiang, Yilun; Fu, Qingyan; Lin, Yanfen; Huang, Kan; Zhuang, Guoshun

    2018-03-01

    Near-surface and vertical in situ measurements of atmospheric particles were conducted in Shanghai during 19-23 March 2010 to explore the transport and chemical evolution of dust particles in a super dust storm. An air quality model with optimized physical dust emission scheme and newly implemented dust chemistry was utilized to study the impact of dust chemistry on regional air quality. Two discontinuous dust periods were observed with one traveling over northern China (DS1) and the other passing over the coastal regions of eastern China (DS2). Stronger mixing extents between dust and anthropogenic emissions were found in DS2, reflected by the higher SO2 / PM10 and NO2 / PM10 ratios as well as typical pollution elemental species such as As, Cd, Pb, and Zn. As a result, the concentrations of SO42- and NO3- and the ratio of Ca2+ / Ca were more elevated in DS2 than in DS1 but opposite for the [NH4+] / [SO42-+NO3-] ratio, suggesting the heterogeneous reactions between calcites and acid gases were significantly promoted in DS2 due to the higher level of relative humidity and gaseous pollution precursors. Lidar observation showed a columnar effect on the vertical structure of particle optical properties in DS1 that dust dominantly accounted for ˜ 80-90 % of the total particle extinction from near the ground to ˜ 700 m. In contrast, the dust plumes in DS2 were restrained within lower altitudes while the extinction from spherical particles exhibited a maximum at a high altitude of ˜ 800 m. The model simulation reproduced relatively consistent results with observations that strong impacts of dust heterogeneous reactions on secondary aerosol formation occurred in areas where the anthropogenic emissions were intensive. Compared to the sulfate simulation, the nitrate formation on dust is suggested to be improved in the future modeling efforts.

  6. Size-resolved dust and aerosol contaminants associated with copper and lead smelting emissions: Implications for emission management and human health

    International Nuclear Information System (INIS)

    Csavina, Janae; Taylor, Mark P.; Félix, Omar; Rine, Kyle P.; Eduardo Sáez, A.; Betterton, Eric A.

    2014-01-01

    Mining operations, including crushing, grinding, smelting, refining, and tailings management, are a significant source of airborne metal and metalloid contaminants such as As, Pb and other potentially toxic elements. In this work, we show that size-resolved concentrations of As and Pb generally follow a bimodal distribution with the majority of contaminants in the fine size fraction (< 1 μm) around mining activities that include smelting operations at various sites in Australia and Arizona. This evidence suggests that contaminated fine particles (< 1 μm) are the result of vapor condensation and coagulation from smelting operations while coarse particles are most likely the result of windblown dust from contaminated mine tailings and fugitive emissions from crushing and grinding activities. These results on the size distribution of contaminants around mining operations are reported to demonstrate the ubiquitous nature of this phenomenon so that more effective emission management and practices that minimize health risks associated with metal extraction and processing can be developed. - Highlights: • Lead and copper smelting produce significant atmospheric concentrations of lead and arsenic. • Atmospheric lead and arsenic concentrations depend on particle size. • Lead isotopic analysis can be used to assess source of atmospheric contamination from smelters

  7. Size-resolved dust and aerosol contaminants associated with copper and lead smelting emissions: Implications for emission management and human health

    Energy Technology Data Exchange (ETDEWEB)

    Csavina, Janae [Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721 (United States); Taylor, Mark P. [Environmental Science, Faculty of Science, Macquarie University, North Ryde, Sydney, NSW 2109 (Australia); Félix, Omar [Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721 (United States); Rine, Kyle P. [Department of Atmospheric Sciences, The University of Arizona, Tucson, AZ 85721 (United States); Eduardo Sáez, A., E-mail: esaez@email.arizona.edu [Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721 (United States); Betterton, Eric A., E-mail: betterton@atmo.arizona.edu [Department of Atmospheric Sciences, The University of Arizona, Tucson, AZ 85721 (United States)

    2014-09-15

    Mining operations, including crushing, grinding, smelting, refining, and tailings management, are a significant source of airborne metal and metalloid contaminants such as As, Pb and other potentially toxic elements. In this work, we show that size-resolved concentrations of As and Pb generally follow a bimodal distribution with the majority of contaminants in the fine size fraction (< 1 μm) around mining activities that include smelting operations at various sites in Australia and Arizona. This evidence suggests that contaminated fine particles (< 1 μm) are the result of vapor condensation and coagulation from smelting operations while coarse particles are most likely the result of windblown dust from contaminated mine tailings and fugitive emissions from crushing and grinding activities. These results on the size distribution of contaminants around mining operations are reported to demonstrate the ubiquitous nature of this phenomenon so that more effective emission management and practices that minimize health risks associated with metal extraction and processing can be developed. - Highlights: • Lead and copper smelting produce significant atmospheric concentrations of lead and arsenic. • Atmospheric lead and arsenic concentrations depend on particle size. • Lead isotopic analysis can be used to assess source of atmospheric contamination from smelters.

  8. Forsythia suspensa Suppresses House Dust Mite Extract-Induced Atopic Dermatitis in NC/Nga Mice.

    Science.gov (United States)

    Sung, Yoon-Young; Yoon, Taesook; Jang, Seol; Kim, Ho Kyoung

    2016-01-01

    Forsythia suspensa (F. suspensa) is a traditional medicine for treatment of inflammation. In this study, we evaluated the therapeutic effects of an ethanol extract from F. suspensa fruits on atopic dermatitis both in vivo and in vitro. We investigated the inhibitory effects of F. suspensa extract on the development of atopic dermatitis-like skin lesions in an NC/Nga mouse model exposed to Dermatophagoides farinae crude extract. Topical application of F. suspensa extract to the mice attenuated the atopic dermatitis symptoms, including increased dermatitis severity score, ear thickness, infiltration of inflammatory cells in the skin lesions, serum levels of IgE, TNF-α, and histamine, and expression of chemokines, cytokines, and adhesion molecules in ear tissue. In addition, F. suspensa extract inhibited the production of chemokines in TNF-α/IFN-γ-activated human keratinocytes. High-performance liquid chromatography analysis of FSE revealed the presence of four chemical constituents (forsythiaside, phillyrin, pinoresinol, and phylligenin). These compounds inhibited the production of chemokines in TNF-α/IFN-γ-activated human keratinocytes. These results suggest that the F. suspensa might be a useful candidate for treating allergic skin inflammatory disorders.

  9. Forsythia suspensa Suppresses House Dust Mite Extract-Induced Atopic Dermatitis in NC/Nga Mice

    OpenAIRE

    Sung, Yoon-Young; Yoon, Taesook; Jang, Seol; Kim, Ho Kyoung

    2016-01-01

    Forsythia suspensa (F. suspensa) is a traditional medicine for treatment of inflammation. In this study, we evaluated the therapeutic effects of an ethanol extract from F. suspensa fruits on atopic dermatitis both in vivo and in vitro. We investigated the inhibitory effects of F. suspensa extract on the development of atopic dermatitis-like skin lesions in an NC/Nga mouse model exposed to Dermatophagoides farinae crude extract. Topical application of F. suspensa extract to the mice attenuated...

  10. Forsythia suspensa Suppresses House Dust Mite Extract-Induced Atopic Dermatitis in NC/Nga Mice.

    Directory of Open Access Journals (Sweden)

    Yoon-Young Sung

    Full Text Available Forsythia suspensa (F. suspensa is a traditional medicine for treatment of inflammation. In this study, we evaluated the therapeutic effects of an ethanol extract from F. suspensa fruits on atopic dermatitis both in vivo and in vitro. We investigated the inhibitory effects of F. suspensa extract on the development of atopic dermatitis-like skin lesions in an NC/Nga mouse model exposed to Dermatophagoides farinae crude extract. Topical application of F. suspensa extract to the mice attenuated the atopic dermatitis symptoms, including increased dermatitis severity score, ear thickness, infiltration of inflammatory cells in the skin lesions, serum levels of IgE, TNF-α, and histamine, and expression of chemokines, cytokines, and adhesion molecules in ear tissue. In addition, F. suspensa extract inhibited the production of chemokines in TNF-α/IFN-γ-activated human keratinocytes. High-performance liquid chromatography analysis of FSE revealed the presence of four chemical constituents (forsythiaside, phillyrin, pinoresinol, and phylligenin. These compounds inhibited the production of chemokines in TNF-α/IFN-γ-activated human keratinocytes. These results suggest that the F. suspensa might be a useful candidate for treating allergic skin inflammatory disorders.

  11. Compton suppression gamma ray spectrometry

    International Nuclear Information System (INIS)

    Landsberger, S.; Iskander, F.Y.; Niset, M.; Heydorn, K.

    2002-01-01

    In the past decade there have been many studies to use Compton suppression methods in routine neutron activation analysis as well as in the traditional role of low level gamma ray counting of environmental samples. On a separate path there have been many new PC based software packages that have been developed to enhance photopeak fitting. Although the newer PC based algorithms have had significant improvements, they still suffer from being effectively used in weak gamma ray lines in natural samples or in neutron activated samples that have very high Compton backgrounds. We have completed a series of experiments to show the usefulness of Compton suppression. As well we have shown the pitfalls when using Compton suppression methods for high counting deadtimes as in the case of neutron activated samples. We have also investigated if counting statistics are the same both suppressed and normal modes. Results are presented in four separate experiments. (author)

  12. Thyroid suppression test with dextrothyroxine

    International Nuclear Information System (INIS)

    Rosenthal, D.; Fridman, J.; Ribeiro, H.B.

    1978-01-01

    The classic thyroid suppression test with triiodothyronine (l-T 3 ) has been shown to be efficient as an auxiliary method in the diagnosis of thyroid diseases, but should not be performed on elderly patients or on those with heart disease or a tendency to tachycardia. Since these subjects seem able to support a short period of dextro-thyronine (d-T 4 ) feeding, we compared the effect of d-T 4 and l-T 3 on the 24 hours thyroid uptake in euthyroid and hyperthyroid subjects. After basal radio-iodine uptake determination, 99 patients without hyperthyroidism and 27 with Graves' disease were randomly divided in 2 groups; one received 100μg of l-T 3 per day and the other 4 mg of d-T 4 per day, both groups being treated for a period of 10 days. At the end of this suppression period the 24 hours radio-iodine uptake was measured again and the percentual suppression index (S.I.) calculated. Since the comparison of the two groups showed no difference between the suppressive effect of l-T 3 and d-T 4 in euthyroid subjects, while dextro-thyronine, as levo-triiodothyronine, did not suppress the 24 hours uptake of hyperthyroid patients, l-T 3 or d-T 4 can be used interchangeably to test thyroid suppressibility. In the euthyroid subjects the normal range for the post-suppression uptake was 0-17.1% and for the suppression index 54,7.100% [pt

  13. In vivo Treg suppression assays.

    Science.gov (United States)

    Workman, Creg J; Collison, Lauren W; Bettini, Maria; Pillai, Meenu R; Rehg, Jerold E; Vignali, Dario A A

    2011-01-01

    To fully examine the functionality of a regulatory T cell (T(reg)) population, one needs to assess their ability to suppress in a variety of in vivo models. We describe five in vivo models that examine the suppressive capacity of T(regs) upon different target cell types. The advantages and disadvantages of each model including resources, time, and technical expertise required to execute each model are also described.

  14. In Vivo Treg Suppression Assays

    OpenAIRE

    Workman, Creg J.; Collison, Lauren W.; Bettini, Maria; Pillai, Meenu R.; Rehg, Jerold E.; Vignali, Dario A.A.

    2011-01-01

    To fully examine the functionality of a regulatory T cell (Treg) population, one needs to assess their ability to suppress in a variety of in vivo models. We describe five in vivo models that examine the suppressive capacity of Tregs upon different target cell types. The advantages and disadvantages of each model includ ing resources, time, and technical expertise required to execute each model are also described.

  15. Dust Destruction in the ISM: A Re-Evaluation of Dust Lifetimes

    Science.gov (United States)

    Jones, A. P.; Nuth, J. A., III

    2011-01-01

    There is a long-standing conundrum in interstellar dust studies relating to the discrepancy between the time-scales for dust formation from evolved stars and the apparently more rapid destruction in supernova-generated shock waves. Aims. We re-examine some of the key issues relating to dust evolution and processing in the interstellar medium. Methods. We use recent and new constraints from observations, experiments, modelling and theory to re-evaluate dust formation in the interstellar medium (ISM). Results. We find that the discrepancy between the dust formation and destruction time-scales may not be as significant as has previously been assumed because of the very large uncertainties involved. Conclusions. The derived silicate dust lifetime could be compatible with its injection time-scale, given the inherent uncertainties in the dust lifetime calculation. The apparent need to re-form significant quantities of silicate dust in the tenuous interstellar medium may therefore not be a strong requirement. Carbonaceous matter, on the other hand, appears to be rapidly recycled in the ISM and, in contrast to silicates, there are viable mechanisms for its re-formation in the ISM.

  16. Head-on collision of dust-ion-acoustic solitons in electron-dust-ion ...

    Indian Academy of Sciences (India)

    March 2013 physics pp. 519–531. Head-on collision of dust-ion-acoustic solitons in electron-dust-ion quantum plasmas. PRASANTA CHATTERJEE1, MALAY KUMAR GHORUI1,2,∗ and RAJKUMAR ROYCHOUDHURY3. 1Department of Mathematics, Siksha Bhavana, Visva Bharati University,. Santiniketan 731 235, India.

  17. Dust-cyclotron and dust-lower-hybrid modes in self-gravitating ...

    Indian Academy of Sciences (India)

    cantly modifies the dispersion properties of these two electrostatic modes. The implications of these results to some space and astrophysical dusty plasma systems, especially to planetary ring-systems and cometary tails, are briefly mentioned. Keywords. Dusty plasmas; dust-cyclotron waves; dust-lower-hybrid waves.

  18. CHARACTERIZATION OF THE DUST GENERATED IN THE RECYCLING PROCESS OF THE ELECTRIC ARC FURNACE DUST

    Directory of Open Access Journals (Sweden)

    Fábio Gonçalves Rizz

    2013-10-01

    Full Text Available Electric Arc Furnace Dust (EAFD is a solid waste generated by the production of steel through the Electric Arc Furnace. This waste is labeled dangerous, which motivates studies aiming its recycling. Experiments were made to study a pyrometallurgical process for the recycling of the dust, using the insertion of dust briquettes in molten pig iron in three temperatures. In the briquettes, there were made additions of calcium fluoride in four different concentrations. This paper has the objective to characterize the dust that results from this process, verifying the influence of the temperature and the concentration of calcium fluoride in the briquette in the morphology and chemical composition of the new dust, determining the optimal conditions for the recovery of the zinc content of the dust. This newly generated dust was analyzed in an Scanning Electronic Microscope, used to capture micrographs and chemical composition by EDS. The micrographs show that the temperature and the calcium fluoride concentration interfere in the way the dust particles agglomerate. Chemical analysis points that the higher zinc recuperation occurrs in the experiments at 1500°C with 7% addition of calcium fluoride.

  19. The flow of interstellar dust through the solar system: the role of dust charging

    International Nuclear Information System (INIS)

    Sterken, V. J.; Altobelli, N.; Schwehm, G.; Kempf, S.; Srama, R.; Strub, P.; Gruen, E.

    2011-01-01

    Interstellar dust can enter the solar system through the relative motion of the Sun with respect to the Local Interstellar Cloud. The trajectories of the dust through the solar system are not only influenced by gravitation and solar radiation pressure forces, but also by the Lorentz forces due to the interaction of the interplanetary magnetic field with the charged dust particles. The interplanetary magnetic field changes on two major time scales: 25 days (solar rotation frequency) and 22 years (solar cycle). The short-term variability averages out for regions that are not too close (>∼2 AU) to the Sun. This interplanetary magnetic field variability causes a time-variability in the interstellar dust densities, that is correlated to the solar cycle.In this work we characterize the flow of interstellar dust through the solar system using simulations of the dust trajectories. We start from the simple case without Lorentz forces, and expand to the full simulation. We pay attention to the different ways of modeling the interplanetary magnetic field, and discuss the influence of the dust parameters on the resulting flow patterns. We also discuss the possibilities of using this modeling for prediction of dust fluxes for different space missions or planets, and we pay attention to where simplified models are justified, and where or when a full simulation, including all forces is necessary. One of the aims of this work is to understand measurements of spacecraft like Ulysses, Cassini and Stardust.

  20. Planar dust-acoustic waves in electron–positron–ion–dust plasmas ...

    Indian Academy of Sciences (India)

    2014-09-19

    Sep 19, 2014 ... Abstract. Propagation of small but finite nonlinear dust-acoustic solitary waves are investigated in a planar unmagnetized dusty plasma, which consists of electrons, positrons, ions and negatively charged dust particles with different sizes and masses. A Kadomtsev–Petviashvili (KP) equation is obtained by ...

  1. Dust acoustic shock wave generation due to dust charge variation in ...

    Indian Academy of Sciences (India)

    Keywords. Non-adiabatic charge variation; shock wave. Abstract. In a dusty plasma, the non-adiabaticity of the charge variation on a dust grain surface results in an anomalous dissipation. Analytical investigation shows that this results in a small but finite amplitude dust acoustic (DA) wave propagation which is described by ...

  2. A Dynamic Enhancement With Background Reduction Algorithm: Overview and Application to Satellite-Based Dust Storm Detection

    Science.gov (United States)

    Miller, Steven D.; Bankert, Richard L.; Solbrig, Jeremy E.; Forsythe, John M.; Noh, Yoo-Jeong; Grasso, Lewis D.

    2017-12-01

    This paper describes a Dynamic Enhancement Background Reduction Algorithm (DEBRA) applicable to multispectral satellite imaging radiometers. DEBRA uses ancillary information about the clear-sky background to reduce false detections of atmospheric parameters in complex scenes. Applied here to the detection of lofted dust, DEBRA enlists a surface emissivity database coupled with a climatological database of surface temperature to approximate the clear-sky equivalent signal for selected infrared-based multispectral dust detection tests. This background allows for suppression of false alarms caused by land surface features while retaining some ability to detect dust above those problematic surfaces. The algorithm is applicable to both day and nighttime observations and enables weighted combinations of dust detection tests. The results are provided quantitatively, as a detection confidence factor [0, 1], but are also readily visualized as enhanced imagery. Utilizing the DEBRA confidence factor as a scaling factor in false color red/green/blue imagery enables depiction of the targeted parameter in the context of the local meteorology and topography. In this way, the method holds utility to both automated clients and human analysts alike. Examples of DEBRA performance from notable dust storms and comparisons against other detection methods and independent observations are presented.

  3. Burst Suppression for ICP Control.

    Science.gov (United States)

    Zeiler, Frederick A; Akoth, Eva; Gillman, Lawrence M; West, Michael

    2017-02-01

    The goal of our study was to perform a systematic review of the literature to determine the effect that burst suppression has on intracranial pressure (ICP) control. All articles from MEDLINE, BIOSIS, EMBASE, Global Health, Scopus, Cochrane Library, the International Clinical Trials Registry Platform (inception to January 2015), reference lists of relevant articles, and gray literature were searched. The strength of evidence was adjudicated using both the Oxford and the Grading of Recommendation Assessment Development and Education (GRADE) methodology. Seven articles were considered for review. A total of 108 patients were studied, all receiving burst suppression therapy. Two studies failed to document a decrease in ICP with burst suppression therapy. There were reports of severe hypotension and increased infection rates with barbiturate-based therapy. Etomidate-based suppressive therapy was linked to severe renal dysfunction. There currently exists both Oxford level 2b and GRADE C evidence to support that achieving burst suppression reduces ICP, and also has no effect on ICP, in severe traumatic brain injury. The literature suggests burst suppression therapy may be useful for ICP reduction in certain cases, although these situations are currently unclear. In addition, the impact on patient functional outcome is unclear. Further prospective study is warranted.

  4. Dust Combustion Safety Issues for Fusion Applications

    Energy Technology Data Exchange (ETDEWEB)

    L. C. Cadwallader

    2003-05-01

    This report summarizes the results of a safety research task to identify the safety issues and phenomenology of metallic dust fires and explosions that are postulated for fusion experiments. There are a variety of metal dusts that are created by plasma erosion and disruptions within the plasma chamber, as well as normal industrial dusts generated in the more conventional equipment in the balance of plant. For fusion, in-vessel dusts are generally mixtures of several elements; that is, the constituent elements in alloys and the variety of elements used for in-vessel materials. For example, in-vessel dust could be composed of beryllium from a first wall coating, tungsten from a divertor plate, copper from a plasma heating antenna or diagnostic, and perhaps some iron and chromium from the steel vessel wall or titanium and vanadium from the vessel wall. Each of these elements has its own unique combustion characteristics, and mixtures of elements must be evaluated for the mixture’s combustion properties. Issues of particle size, dust temperature, and presence of other combustible materials (i.e., deuterium and tritium) also affect combustion in air. Combustion in other gases has also been investigated to determine if there are safety concerns with “inert” atmospheres, such as nitrogen. Several coolants have also been reviewed to determine if coolant breach into the plasma chamber would enhance the combustion threat; for example, in-vessel steam from a water coolant breach will react with metal dust. The results of this review are presented here.

  5. Electrostatic Dust Detection and Removal for ITER

    International Nuclear Information System (INIS)

    C.H. Skinner; A. Campos; H. Kugel; J. Leisure; A.L. Roquemore; S. Wagner

    2008-01-01

    We present some recent results on two innovative applications of microelectronics technology to dust inventory measurement and dust removal in ITER. A novel device to detect the settling of dust particles on a remote surface has been developed in the laboratory. A circuit board with a grid of two interlocking conductive traces with 25 (micro)m spacing is biased to 30-50 V. Carbon particles landing on the energized grid create a transient short circuit. The current flowing through the short circuit creates a voltage pulse that is recorded by standard nuclear counting electronics and the total number of counts is related to the mass of dust impinging on the grid. The particles typically vaporize in a few seconds restoring the previous voltage standoff. Experience on NSTX however, showed that in a tokamak environment it was still possible for large particles or fibers to remain on the grid causing a long term short circuit. We report on the development of a gas puff system that uses helium to clear such particles. Experiments with varying nozzle designs, backing pressures, puff durations, and exit flow orientations have given an optimal configuration that effectively removes particles from an area up to 25 cm 2 with a single nozzle. In a separate experiment we are developing an advanced circuit grid of three interlocking traces that can generate a miniature electrostatic traveling wave for transporting dust to a suitable exit port. We have fabricated such a 3-pole circuit board with 25 micron insulated traces that operates with voltages up to 200 V. Recent results showed motion of dust particles with the application of only 50 V bias voltage. Such a device could potentially remove dust continuously without dedicated interventions and without loss of machine availability for plasma operations

  6. Diagnostics of mobile dust in scrape-off layer plasmas

    International Nuclear Information System (INIS)

    Ratynskaia, S; Castaldo, C; Bergsaaker, H; Rudakov, D

    2011-01-01

    Dust production and accumulation pose serious safety and operational implications for the next generation fusion devices. Mobile dust particles can result in core plasma contamination with impurities, and those with high velocities can significantly contribute to the wall erosion. Diagnostics for monitoring dust in tokamaks during plasma discharges are hence important as they can provide information on dust velocity and size, and-in some cases-on dust composition. Such measurements are also valuable as an input for theoretical models of dust dynamics in scrape-off layer plasmas. Existing in situ dust diagnostics, focusing on the range of dust parameters they can detect, are reviewed. Particular attention is paid to the diagnostics which allow us to detect tails of the dust velocity and size distributions, e.g. small and very fast particles. Some of the techniques discussed have been adopted from space-related research and have been shown to be feasible and useful for tokamak applications as well.

  7. Suppressed Charmed B Decay

    Energy Technology Data Exchange (ETDEWEB)

    Snoek, Hella Leonie [Vrije Univ., Amsterdam (Netherlands)

    2009-06-02

    This thesis describes the measurement of the branching fractions of the suppressed charmed B0 → D*- a0+ decays and the non-resonant B0 → D*- ηπ+ decays in approximately 230 million Υ(4S) → B$\\bar{B}$ events. The data have been collected with the BABAR detector at the PEP-II B factory at the Stanford Linear Accelerator Center in California. Theoretical predictions of the branching fraction of the B0 → D*- a{sub 0}+ decays show large QCD model dependent uncertainties. Non-factorizing terms, in the naive factorization model, that can be calculated by QCD factorizing models have a large impact on the branching fraction of these decay modes. The predictions of the branching fractions are of the order of 10-6. The measurement of the branching fraction gives more insight into the theoretical models. In general a better understanding of QCD models will be necessary to conduct weak interaction physics at the next level. The presence of CP violation in electroweak interactions allows the differentiation between matter and antimatter in the laws of physics. In the Standard Model, CP violation is incorporated in the CKM matrix that describes the weak interaction between quarks. Relations amongst the CKM matrix elements are used to present the two relevant parameters as the apex of a triangle (Unitarity Triangle) in a complex plane. The over-constraining of the CKM triangle by experimental measurements is an important test of the Standard Model. At this moment no stringent direct measurements of the CKM angle γ, one of the interior angles of the Unitarity Triangle, are available. The measurement of the angle γ can be performed using the decays of neutral B mesons. The B0 → D*- a0+ decay is sensitive to the angle γ and, in comparison to the current decays that are being employed, could significantly

  8. A simplified Suomi NPP VIIRS dust detection algorithm

    Science.gov (United States)

    Yang, Yikun; Sun, Lin; Zhu, Jinshan; Wei, Jing; Su, Qinghua; Sun, Wenxiao; Liu, Fangwei; Shu, Meiyan

    2017-11-01

    Due to the complex characteristics of dust and sparse ground-based monitoring stations, dust monitoring is facing severe challenges, especially in dust storm-prone areas. Aim at constructing a high-precision dust storm detection model, a pixel database, consisted of dusts over a variety of typical feature types such as cloud, vegetation, Gobi and ice/snow, was constructed, and their distributions of reflectance and Brightness Temperatures (BT) were analysed, based on which, a new Simplified Dust Detection Algorithm (SDDA) for the Suomi National Polar-Orbiting Partnership Visible infrared Imaging Radiometer (NPP VIIRS) is proposed. NPP VIIRS images covering the northern China and Mongolian regions, where features serious dust storms, were selected to perform the dust detection experiments. The monitoring results were compared with the true colour composite images, and results showed that most of the dust areas can be accurately detected, except for fragmented thin dusts over bright surfaces. The dust ground-based measurements obtained from the Meteorological Information Comprehensive Analysis and Process System (MICAPS) and the Ozone Monitoring Instrument Aerosol Index (OMI AI) products were selected for comparison purposes. Results showed that the dust monitoring results agreed well in the spatial distribution with OMI AI dust products and the MICAPS ground-measured data with an average high accuracy of 83.10%. The SDDA is relatively robust and can realize automatic monitoring for dust storms.

  9. Sr-Nd-Hf Isotopic Analysis of Dust Samples: Implications for Ice Core Dust Source Fingerprinting

    Science.gov (United States)

    Újvári, Gábor; Wegner, Wencke; Klötzli, Urs; Horschinegg, Monika; Hippler, Dorothee

    2018-01-01

    Combined Sr-Nd-Hf isotopic data of two reference materials (AGV-1/BCR2) and 50, 10, and 5 mg aliquots of carbonate-free fine grain (China/BEI, USA/JUD) are presented. Good agreement between measured and reference Sr-Nd-Hf isotopic compositions (ICs) demonstrate that robust isotopic ratios can be obtained from 5 to 10 mg size rock samples using the ion exchange/mass spectrometry techniques applied. While 87Sr/86Sr ratios of dust aluminosilicate fractions are affected by even small changes in pretreatments, Nd isotopic ratios are found to be insensitive to acid leaching, grain-size or weathering effects. However, the Nd isotopic tracer is sometimes inconclusive in dust source fingerprinting (BEI and NUS both close to ɛNd(0) -10). Hafnium isotopic values (dust dust from potential source areas to gain more insight into the origin of last glacial dust in Greenland ice cores.

  10. Dust storms and their impact on ocean and human health: dust in Earth's atmosphere

    Science.gov (United States)

    Griffin, Dale W.; Kellog, Christina A.

    2004-01-01

    Satellite imagery has greatly influenced our understanding of dust activity on a global scale. A number of different satellites such as NASA's Earth-Probe Total Ozone Mapping Spectrometer (TOMS) and Se-viewing Field-of-view Sensor (SeaWiFS) acquire daily global-scale data used to produce imagery for monitoring dust storm formation and movement. This global-scale imagery has documented the frequent transmission of dust storm-derived soils through Earth's atmosphere and the magnitude of many of these events. While various research projects have been undertaken to understand this normal planetary process, little has been done to address its impact on ocean and human health. This review will address the ability of dust storms to influence marine microbial population densities and transport of soil-associated toxins and pathogenic microorganisms to marine environments. The implications of dust on ocean and human health in this emerging scientific field will be discussed.

  11. Mixing of Dust and NH3 Observed Globally over Anthropogenic Dust Sources

    Science.gov (United States)

    Ginoux, P.; Clarisse, L.; Clerbaux, C.; Coheur, P.-F.; Dubovik, O.; Hsu, N. C.; Van Damme, M.

    2012-01-01

    The global distribution of dust column burden derived from MODIS Deep Blue aerosol products is compared to NH3 column burden retrieved from IASI infrared spectra. We found similarities in their spatial distributions, in particular their hot spots are often collocated over croplands and to a lesser extent pastures. Globally, we found 22% of dust burden collocated with NH3, with only 1% difference between land-use databases. This confirms the importance of anthropogenic dust from agriculture. Regionally, the Indian subcontinent has the highest amount of dust mixed with NH3 (26 %), mostly over cropland and during the pre-monsoon season. North Africa represents 50% of total dust burden but accounts for only 4% of mixed dust, which is found over croplands and pastures in Sahel and the coastal region of the Mediterranean. In order to evaluate the radiative effect of this mixing on dust optical properties, we derive the mass extinction efficiency for various mixtures of dust and NH3, using AERONET sunphotometers data. We found that for dusty days the coarse mode mass extinction efficiency decreases from 0.62 to 0.48 square meters per gram as NH3 burden increases from 0 to 40 milligrams per square meter. The fine mode extinction efficiency, ranging from 4 to 16 square mters per gram, does not appear to depend on NH3 concentration or relative humidity but rather on mineralogical composition and mixing with other aerosols. Our results imply that a significant amount of dust is already mixed with ammonium salt before its long range transport. This in turn will affect dust lifetime, and its interactions with radiation and cloud properties

  12. Pantoea agglomerans: a marvelous bacterium of evil and good.Part I. Deleterious effects: Dust-borne endotoxins and allergens - focus on cotton dust.

    Science.gov (United States)

    Dutkiewicz, Jacek; Mackiewicz, Barbara; Lemieszek, Marta Kinga; Golec, Marcin; Milanowski, Janusz

    2015-01-01

    The ubiquitous Gram-negative bacterium Pantoea agglomerans (synonyms: Enterobacter agglomerans, Erwinia herbicola) is known both as an epiphytic microbe developing on the surface of plants and as an endophytic organism living inside the plants. The bacterium occurs also abundantly in plant and animal products, in the body of arthropods and other animals, in water, soil, dust and air, and occasionally in humans. From the human viewpoint, the role of this organism is ambiguous, both deleterious and beneficial: on one side it causes disorders in people exposed to inhalation of organic dusts and diseases of crops, and on the other side it produces substances effective in the treatment of cancer and other diseases of humans and animals, suppresses the development of various plant pathogens, promotes plant growth, and appears as a potentially efficient biofertilizer and bioremediator. P. agglomerans was identified as a predominant bacterium on cotton plant grown all over the world, usually as an epiphyte, rarely as pathogen. It is particularly numerous on cotton bract after senescence. During processing of cotton in mills, bacteria and their products are released with cotton dust into air and are inhaled by workers, causing respiratory and general disorders, usually defined as byssinosis. The most adverse substance is endotoxin, a heteropolymer macromolecule present in the outermost part of the cell wall, consisting of lipopolysaccharide (LPS) as a major constituent, phospholipids and protein. The numerous experiments carried out in last quarter of XXth century on laboratory animals and human volunteers supported a convincing evidence that the inhaled endotoxin produced by P. agglomerans causes numerous pathologic effects similar to those elicited by cotton dust, such as influx of free lung cells into airways and activation of alveolar macrophages which secrete mediators (prostaglandins, platelet-activating factor, interleukin-1, tumor necrosis factor) that cause

  13. Pantoea agglomerans: a marvelous bacterium of evil and good.Part I. Deleterious effects: Dust-borne endotoxins and allergens – focus on cotton dust

    Directory of Open Access Journals (Sweden)

    Jacek Dutkiewicz

    2015-12-01

    Full Text Available The ubiquitous Gram-negative bacterium Pantoea agglomerans (synonyms: Enterobacter agglomerans, Erwinia herbicola is known both as an epiphytic microbe developing on the surface of plants and as an endophytic organism living inside the plants. The bacterium occurs also abundantly in plant and animal products, in the body of arthropods and other animals, in water, soil, dust and air, and occasionally in humans. From the human viewpoint, the role of this organism is ambiguous, both deleterious and beneficial: on one side it causes disorders in people exposed to inhalation of organic dusts and diseases of crops, and on the other side it produces substances effective in the treatment of cancer and other diseases of humans and animals, suppresses the development of various plant pathogens, promotes plant growth, and appears as a potentially efficient biofertilizer and bioremediator. P. agglomerans was identified as a predominant bacterium on cotton plant grown all over the world, usually as an epiphyte, rarely as pathogen. It is particularly numerous on cotton bract after senescence. During processing of cotton in mills, bacteria and their products are released with cotton dust into air and are inhaled by workers, causing respiratory and general disorders, usually defined as byssinosis. The most adverse substance is endotoxin, a heteropolymer macromolecule present in the outermost part of the cell wall, consisting of lipopolysaccharide (LPS as a major constituent, phospholipids and protein. The numerous experiments carried out in last quarter of XXth century on laboratory animals and human volunteers supported a convincing evidence that the inhaled endotoxin produced by P. agglomerans causes numerous pathologic effects similar to those elicited by cotton dust, such as influx of free lung cells into airways and activation of alveolar macrophages which secrete mediators (prostaglandins, platelet-activating factor, interleukin-1, tumor necrosis factor

  14. Pantoea agglomerans : a marvelous bacterium of evil and good. Part I. Deleterious effects: Dust-borne endotoxins and allergens – focus on cotton dust

    Directory of Open Access Journals (Sweden)

    Jacek Dutkiewicz

    2015-12-01

    Full Text Available The ubiquitous Gram-negative bacterium Pantoea agglomerans (synonyms: Enterobacter agglomerans , Erwinia herbicola is known both as an epiphytic microbe developing on the surface of plants and as an endophytic organism living inside the plants. The bacterium occurs also abundantly in plant and animal products, in the body of arthropods and other animals, in water, soil, dust and air, and occasionally in humans. From the human viewpoint, the role of this organism is ambiguous, both deleterious and beneficial: on one side it causes disorders in people exposed to inhalation of organic dusts and diseases of crops, and on the other side it produces substances effective in the treatment of cancer and other diseases of humans and animals, suppresses the development of various plant pathogens, promotes plant growth, and appears as a potentially efficient biofertilizer and bioremediator. P. agglomerans was identified as a predominant bacterium on cotton plant grown all over the world, usually as an epiphyte, rarely as pathogen. It is particularly numerous on cotton bract after senescence. During processing of cotton in mills, bacteria and their products are released with cotton dust into air and are inhaled by workers, causing respiratory and general disorders, usually defined as byssinosis. The most adverse substance is endotoxin, a heteropolymer macromolecule present in the outermost part of the cell wall, consisting of lipopolysaccharide (LPS as a major constituent, phospholipids and protein. The numerous experiments carried out in last quarter of XXth century on laboratory animals and human volunteers supported a convincing evidence that the inhaled endotoxin produced by P. agglomerans causes numerous pathologic effects similar to those elicited by cotton dust, such as influx of free lung cells into airways and activation of alveolar macrophages which secrete mediators (prostaglandins, platelet-activating factor, interleukin-1, tumor necrosis factor

  15. On the health effects of transported and resuspended dusts

    Science.gov (United States)

    Rudich, Yinon

    2017-04-01

    In the Mediterranean area people are often exposed to high levels of both transported mineral dust and to resuspended urban dust. High exposure to particulate matter is a known risk factor to exposed population, but the detailed understanding of how these dusts affect health remain elusive. In this talk I will describe two aspects of how dust may impact health. First, transport of bacteria by desert dust and its effects on the local microbiome will be described. Then, we will describe the biological effects due to exposing water soluble extracts of fresh and aged dust particles from the Israeli Negev Desert to alveolar macrophages.

  16. Experimental Method for Measuring Dust Load on Surfaces in Rooms

    DEFF Research Database (Denmark)

    Lengweiler, Philip; Nielsen, Peter V.; Moser, Alfred

    , there is a need for better understanding of the mechanism of dust deposition and resuspension. With the presented experimental setup, the dust load on surfaces in a channel can be measured as a function of the environmental and surface conditions and the type of particles under controlled laboratory conditions.......A new experimental setup to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airborne dust concentration considerably. As a basis for developing methods to eliminate dust-related problems in rooms...

  17. Mechanical intervention for reducing dust concentration in traditional rice mills

    OpenAIRE

    PRANAV, Prabhanjan K.; BISWAS, Mrinmoy

    2016-01-01

    A huge number of workers are employed in traditional rice mills where they are potentially exposed to dust. In this study a dust collection system was developed to capture the airborne dust in the rice mill. The feeding and sieving section of the mill was identified as major dust creating zone. The dust was captured by creating suitable air stream at feeding and sieving sections of the mill and collected in cyclone dust collector. The air stream was created by blower which was selected on the...

  18. [Dust and occupational diseases in brickyards].

    Science.gov (United States)

    Wiecek, E; Gościcki, J; Indulski, J; Stroszejn-Mrowca, G

    1983-01-01

    Air dustiness and mineralogical composition of dust in 9 building ceramics plants producing red brick were tested. Also analysed were occupational diseases diagnosed in Poland during 1979-1980 in workers of this industry. Concentrations of total dust and respirable fraction at all workstations exceeded the present mandatory allowable values for dusts containing free crystalline silica. By X-ray diffraction, alpha-quartz and illite were found in raw materials (clays) and intermediate products (green brick). In burnt brick alpha-quartz and mullite were found. The content of free crystalline silica was: in clay--over 30%, in total dust--5.8-18.4%, in respirable fraction 3.7-6.1%. Analysis of occupational diseases diagnosed in Poland during 1979-1980 revealed not a single case of pneumoconiosis or any dust--induced respiratory tract disease in those producing red brick. Instead, two pneumoconiosis cases were found among workers of the plant producing thermallite firebrick of biologically aggressive siliceous earth from Piotrowice--as one of its component. Most frequently, workers of the building ceramics plant were afflicted with occupational dermatoses, mostly this relates to bricklayers exposed to cement mortar. Two cases of occupational dermatosis were those of workers exposed to ash.

  19. Dust Disks Around Young Stellar Objects

    Directory of Open Access Journals (Sweden)

    Kyung-Won Suh

    2016-06-01

    Full Text Available To reproduce the spectral energy distributions (SEDs of young stellar objects (YSOs, we perform radiative transfer model calculations for the circumstellar dust disks with various shapes and many dust species. For eight sample objects of T Tauri and Herbig Ae/Be stars, we compare the theoretical model SEDs with the observed SEDs described by the infrared space observatory and Spitzer space telescope spectral data. We use the model, CGPLUS, for a passive irradiated circumstellar dust disk with an inner hole and an inner rim for the eight sample YSOs. We present model parameters for the dust disk, which reproduce the observed SEDs. We find that the model requires a higher mass, luminosity, and temperature for the central star for the Herbig Ae/Be stars than those for the T Tauri stars. Generally, the outer radius, total mass, thickness, and rim height of the theoretical dust disk for the Herbig Ae/Be stars are larger than those for the T Tauri stars.

  20. Maintaining the Background Dust Opacity During Northern Hemisphere Summer Mars Using Wind Stress Based Dust Lifting

    Science.gov (United States)

    Jha, V.; Kahre, M. A.

    2017-12-01

    The Mars atmosphere has low levels of dust during Northern Hemisphere (NH) spring and summer (the non-dusty season) and increased levels during NH autumn and winter (the dusty season). In the absence of regional or global storms, dust devils and local storms maintain a background minimum dust loading during the non-dusty season. While observational surveys and Global Climate Model (GCM) studies suggest that dust devils are likely to be major contributors to the background haze during NH spring and summer, a complete understanding of the relative contribution of dust devils and local dust storms has not yet been achieved. We present preliminary results from an investigation that focuses on the effects of radiatively active water ice clouds on dust lifting processes during these seasons. Water ice clouds are known to affect atmospheric temperatures directly by absorption and emission of thermal infrared radiation and indirectly through dynamical feedbacks. Our goal is to understand how clouds affect the contribution by local (wind stress) dust storms to the background dust haze during NH spring and summer. The primary tool for this work is the NASA Ames Mars GCM, which contains physical parameterizations for a fully interactive dust cycle. Three simulations that included wind stress dust lifting were executed for a period of 5 Martian years: a case that included no cloud formation, a case that included radiatively inert cloud formation and a case that included radiatively active cloud (RAC) formation. Results show that when radiatively active clouds are included, the clouds in the aphelion cloud belt radiatively heat the atmosphere aloft in the tropics (Figure 1). This heating produces a stronger overturning circulation, which in turn produces an enhanced low-level flow in the Hadley cell return branch. The stronger low-level flow drives higher surface stresses and increased dust lifting in those locations. We examine how realistic these simulated results are by

  1. A SUBMILLIMETER CONTINUUM SURVEY OF LOCAL DUST-OBSCURED GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Chul [Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of); Hwang, Ho Seong [School of Physics, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 02455 (Korea, Republic of); Lee, Gwang-Ho, E-mail: jclee@kasi.re.kr [Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of)

    2016-12-20

    We conduct a 350 μ m dust continuum emission survey of 17 dust-obscured galaxies (DOGs) at z = 0.05–0.08 with the Caltech Submillimeter Observatory (CSO). We detect 14 DOGs with S{sub 350μm} = 114–650 mJy and signal-to-noise > 3. By including two additional DOGs with submillimeter data in the literature, we are able to study dust content for a sample of 16 local DOGs, which consist of 12 bump and four power-law types. We determine their physical parameters with a two-component modified blackbody function model. The derived dust temperatures are in the range 57–122 K and 22–35 K for the warm and cold dust components, respectively. The total dust mass and the mass fraction of the warm dust component are 3–34 × 10{sup 7} M {sub ⊙} and 0.03%–2.52%, respectively. We compare these results with those of other submillimeter-detected infrared luminous galaxies. The bump DOGs, the majority of the DOG sample, show similar distributions of dust temperatures and total dust mass to the comparison sample. The power-law DOGs show a hint of smaller dust masses than other samples, but need to be tested with a larger sample. These findings support that the reason DOGs show heavy dust obscuration is not an overall amount of dust content, but probably the spatial distribution of dust therein.

  2. Energetics study of West African dust haze

    International Nuclear Information System (INIS)

    Omotosho, J.B.

    1988-10-01

    The causes of the large and often persistent negative anomalies of equivalent potential temperature observed in the 900-700 hpa layer and which occurs in association with dust haze outbreaks over Kano in winter is investigated. Energetics results indicate that the primary mechanism for such anomalies is the horizontal transport of drier and, to a lesser extent, colder air at the upper levels by eddy motions, with consequent destabilization of the atmospheric boundary layer over the station. This is suggested as the mobilization mechanism responsible for raising dust from the surface over the Bilma/Faya-Largeau source region much further poleward. Temperature inversions were also found to be more pronounced during dust spells than in clear periods. (author). 18 refs, 6 figs, 2 tabs

  3. Absorption and emission characteristics of interstellar dust

    International Nuclear Information System (INIS)

    Allamandola, L.J.

    1984-01-01

    Molecular transitions which occur in the middle infrared region of the spectrum correspond with the characteristic frequencies of molecular vibrations. Thus, moderate resolution spectroscopy of the interstellar medium offers unique evidence about the molecules in the condensed and gaseous phases and their distribution. The author discusses the spectral properties of the condensed phase. However, in the astrophysical literature, it is difficult to find a qualitative description of the effects the solid state has on molecular vibrations, and since it is these which largely determine the spectroscopic properties of the interstellar dust, this discussion begins with a general description of these effects and then is directed toward describing the optical characteristics of the molecular ice component of the dust. The properties of this component of the dust are stressed, rather than those expected from more homogeneous components such as silicates, graphite, or amorphous carbon since these have been discussed in considerable detail elsewhere. (Auth.)

  4. Dust Evolution and the Formation of Planetesimals

    Science.gov (United States)

    Birnstiel, T.; Fang, M.; Johansen, A.

    2016-12-01

    The solid content of circumstellar disks is inherited from the interstellar medium: dust particles of at most a micrometer in size. Protoplanetary disks are the environment where these dust grains need to grow at least 13 orders of magnitude in size. Our understanding of this growth process is far from complete, with different physics seemingly posing obstacles to this growth at various stages. Yet, the ubiquity of planets in our galaxy suggests that planet formation is a robust mechanism. This chapter focuses on the earliest stages of planet formation, the growth of small dust grains towards the gravitationally bound "planetesimals", the building blocks of planets. We will introduce some of the key physics involved in the growth processes and discuss how they are expected to shape the global behavior of the solid content of disks. We will consider possible pathways towards the formation of larger bodies and conclude by reviewing some of the recent observational advances in the field.

  5. New methods and standards for fine dust

    International Nuclear Information System (INIS)

    Spielvogel, Juergen; Hartstock, Stefan; Grimm, Hans

    2009-01-01

    There seems to be common agreement that PM10 is a suboptimal quantity for the quantification of potential dangers from fine dust due to a number of reasons, notably because the chemical composition of the particles is not considered, because the size distribution is disregarded, and because of sampling artefacts. In a first step for improving the particle measurements, the European Community has published new directives for ambient air in June 2008 (EU 2008), which as a main part included new regulations for PM2.5 measurements, in addition to the further on valid regulations for PM10. The comparison of PM2.5 and PM10 may allow a source apportionment and a better assessment of the influence of fine dust on human health. The source apportionment may allow more effective fine dust reduction strategies.

  6. Toward a quantization of null dust collapse

    Science.gov (United States)

    Vaz, Cenalo; Witten, Louis; Singh, T. P.

    2002-05-01

    Spherically symmetric, null dust clouds, like their timelike counterparts, may collapse classically into black holes or naked singularities depending on their initial conditions. We consider the Hamiltonian dynamics of the collapse of an arbitrary distribution of null dust, expressed in terms of the physical radius R, the null coordinates, V for a collapsing cloud or U for an expanding cloud, the mass function m of the null matter, and their conjugate momenta. This description is obtained from the Arnowitt-Deser-Misner description by a Kuchař-type canonical transformation. The constraints are linear in the canonical momenta and Dirac's constraint quantization program is implemented. Explicit solutions to the constraints are obtained for both expanding and contracting null dust clouds with arbitrary mass functions.

  7. Waste and dust utilisation in shaft furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Senk, D.; Babich, A.; Gudenau, H.W. [Rhein Westfal TH Aachen, Aachen (Germany)

    2005-07-01

    Wastes and dusts from steel industry, non-ferrous metallurgy and other branches can be utilised e.g. in agglomeration processes (sintering, pelletising or briquetting) and by injection into shaft furnaces. This paper deals with the second way. Combustion and reduction behaviour of iron- and carbon-rich metallurgical dusts and sludges containing lead, zinc and alkali as well as other wastes with and without pulverised coal (PC) has been studied when injecting into shaft furnaces. Following shaft furnaces have been examined: blast furnace, cupola furnace, OxiCup furnace and imperial-smelting furnace. Investigations have been done at laboratory and industrial scale. Some dusts and wastes under certain conditions can be not only reused but can also improve combustion efficiency at the tuyeres as well as furnace performance and productivity.

  8. Ocular Toxicity Testing of Lunar Dust

    Science.gov (United States)

    Meyers, Valerie E.

    2010-01-01

    This slide presentation reviews the use of ocular testing to determine the toxicity of lunar dust. The OECD recommendations are reviewed. With these recommendations in mind the test methodology was to use EpiOcular, tissues derived from normal human epidermal keratinocytes, the cells of which have been differentiated on cell culture inserts to form a multi-layered structure, which closely parallels the corneal epithelium and to dose the tissue with 100 mg dust from various sources. The in-vitro study provides evidence that lunar dust is not severely corrosive or irritating, however, in vitro tests have limitations, and in vivo tests provides a more complete scenario, and information, it is recommended that in vivo tests be performed.

  9. On rotating charged dust in general relativity

    International Nuclear Information System (INIS)

    Islam, N.J.; Chittagong Univ.

    1983-01-01

    In this paper four main results are derived. Firstly, an exact and explicit non-cylindrically symmetric (but axially symmetric) solution is found for charged dust rotating with constant angular velocity in Newton-Maxwell theory for particles with equal mass and charge. Secondly, a general solution of the main equation is found describing differential rotation in Newton-Maxwell theory for particles of equal mass and charge. Thirdly, a new exact and explicit solution of the cylindrically symmetric Einstein-Maxwell interior equations is derived for charged dust rotating with constant angular velocity. An interesting property of the solution is that it is regular and well behaved for certain values of the parameters occurring in it. Fourthly, it is shown that for cylindrically symmetric, differentially rotating charged dust in general relativity there exists a solution in which the Lorentz force on a typical particle vanishes. (author)

  10. Problems in monitoring dust levels within mines.

    Science.gov (United States)

    Hearl, F J; Hewett, P

    1993-01-01

    The collection of dust samples in mines is a multifaceted problem. Initially, one must define the situation being sampled and the purpose of the sampling in order to establish an appropriate sampling plan, including specification of the type of mining process (surface vs. underground, metal vs. nonmetal vs. coal) as well as the mining system employed (equipment). The next step is to decide the nature of the hazard being monitored (i.e., dust depositing in alveolar air spaces entails use of respirable dust sampling, upper airways entails thoracic-fraction sampler, and systemic effects call for an inhalable-fraction sampler) in order to select the appropriate sampler. Deciding on a particular sampling strategy is a complex issue involving federal regulations as well as compliance.

  11. Identifying sources of aeolian mineral dust: Present and past

    Science.gov (United States)

    Muhs, Daniel R; Prospero, Joseph M; Baddock, Matthew C; Gill, Thomas E

    2014-01-01

    Aeolian mineral dust is an important component of the Earth’s environmental systems, playing roles in the planetary radiation balance, as a source of fertilizer for biota in both terrestrial and marine realms and as an archive for understanding atmospheric circulation and paleoclimate in the geologic past. Crucial to understanding all of these roles of dust is the identification of dust sources. Here we review the methods used to identify dust sources active at present and in the past. Contemporary dust sources, produced by both glaciogenic and non-glaciogenic processes, can be readily identified by the use of Earth-orbiting satellites. These data show that present dust sources are concentrated in a global dust belt that encompasses large topographic basins in low-latitude arid and semiarid regions. Geomorphic studies indicate that specific point sources for dust in this zone include dry or ephemeral lakes, intermittent stream courses, dune fields, and some bedrock surfaces. Back-trajectory analyses are also used to identify dust sources, through modeling of wind fields and the movement of air parcels over periods of several days. Identification of dust sources from the past requires novel approaches that are part of the geologic toolbox of provenance studies. Identification of most dust sources of the past requires the use of physical, mineralogical, geochemical, and isotopic analyses of dust deposits. Physical properties include systematic spatial changes in dust deposit thickness and particle size away from a source. Mineralogy and geochemistry can pinpoint dust sources by clay mineral ratios and Sc-Th-La abundances, respectively. The most commonly used isotopic methods utilize isotopes of Nd, Sr, and Pb and have been applied extensively in dust archives of deep-sea cores, ice cores, and loess. All these methods have shown that dust sources have changed over time, with far more abundant dust supplies existing during glacial periods. Greater dust supplies in

  12. Mineral dust transport toward Hurricane Helene (2006)

    Science.gov (United States)

    Schwendike, Juliane; Jones, Sarah C.; Vogel, Bernhard; Vogel, Heike

    2016-05-01

    This study investigates the transport of mineral dust from its source regions in West Africa toward the developing tropical cyclone Helene (2006) and diagnoses the resulting properties of the air influencing the tropical cyclonegenesis. The model system COSMO-ART (Consortium for Small-Scale Modelling-Aerosols and Reactive Trace gases) in which the emission and transport of mineral dust as well as the radiation feedback are taken into account, was used. The emission of mineral dust between 9 and 14 September 2006 occurred in association with the relatively strong monsoon flow and northeasterly trade winds, with gust fronts of convective systems over land, and with the Atlantic inflow. Additionally, increased surface wind speed was linked to orographical effects at the Algerian Mountains, Atlas Mountains, and the Hoggar. The dust, as part of the Saharan air layer, is transported at low levels by the monsoon flow, the Harmattan, the northeasterly trade winds, and the monsoon trough, and is transported upward in the convergence zone between Harmattan and monsoon flow, in the baroclinic zone along the West African coastline, and by convection. At around 700 hPa the dust is transported by the African easterly jet. Dry and dust-free air is found to the north-northwest of the developing tropical depression due to descent in an anticyclone. Based on the model data, it was possible to distinguish between dry (from the anticyclone), dry and dusty (from the Harmattan and northeasterly trade winds), and dusty and moist air (from the monsoon flow and in the tropical depression due to convection).

  13. Risk of dust explosions of combustible nanomaterials

    International Nuclear Information System (INIS)

    Dobashi, Ritsu

    2009-01-01

    Nanomaterials have several valuable properties and are widely used for various practical applications. However, safety matters are suspected such as the influence on health and environment, and fire and explosion hazards. To minimize the risk of nanomaterials, appropriate understanding of these hazards is indispensable. Nanoparticles of combustible materials have potential hazard of dust explosion accidents. However, the explosion risk of nanomaterials has not yet been understood adequately because of the lack of data for nanomaterials. In this presentation, the risk of dust explosions of nanomaterials is discussed.

  14. PELLETIZING TESTS OF WASTE ANTHRACITE DUST

    Directory of Open Access Journals (Sweden)

    Michał Rejdak

    2016-09-01

    Full Text Available The results of pelletization tests of waste anthracite dust with three types of starch binder, which were performed at the Institute for Chemical Processing of Coal have been presented. The raw material used in pelletization tests was fine-grained anthracite fraction derived from one of the industrial plants processing anthracite. The aim of the research was to determine the possibilities of waste anthracite dust use in terms of its pelletization and determination of the influence of the binder amount on the physico-chemical properties of the obtained pellets. It was stated out that the application of 2,5% starch binder allows obtaining pellets with adequate mechanical strength.

  15. [House dust mite allergy: myths and realities].

    Science.gov (United States)

    Bouton, Christine; Ducommun, Julien

    2009-04-15

    Since 1967, house dust mites have been shown to be the main allergens to be blamed in household dust allergy. In our countries, Dermatophagoides pteronyssinus and Dermatophagoides farinae are predominant. We find them by millions in our bedding. They are responsible of allergic reactions like asthma, rhinitis and atopic dermatitis. Different treatments are available of which some have proved there effectiveness, like subcutaneous immunotherapy and standard symptomatic treatments. On the other hand, the control measures remain controversial and led recently to a lively debate in the medical literature. We felt therefore that it was necessary to set the record straight.

  16. Beyond viral suppression of HIV

    DEFF Research Database (Denmark)

    Lazarus, Jeffrey V.; Safreed-Harmon, Kelly; Barton, Simon E

    2016-01-01

    BACKGROUND: In 2016, the World Health Organization (WHO) adopted a new Global Health Sector Strategy on HIV for 2016-2021. It establishes 15 ambitious targets, including the '90-90-90' target calling on health systems to reduce under-diagnosis of HIV, treat a greater number of those diagnosed......, and ensure that those being treated achieve viral suppression. DISCUSSION: The WHO strategy calls for person-centered chronic care for people living with HIV (PLHIV), implicitly acknowledging that viral suppression is not the ultimate goal of treatment. However, it stops short of providing an explicit target...... for health-related quality of life. It thus fails to take into account the needs of PLHIV who have achieved viral suppression but still must contend with other intense challenges such as serious non-communicable diseases, depression, anxiety, financial stress, and experiences of or apprehension about HIV...

  17. Resonance suppression from color reconnection

    Science.gov (United States)

    Acconcia, R.; Chinellato, D. D.; de Souza, R. Derradi; Takahashi, J.; Torrieri, G.; Markert, C.

    2018-02-01

    We present studies that show how multi-parton interaction and color reconnection affect the hadro-chemistry in proton-proton (pp) collisions with special focus on the production of resonances using the pythia8 event generator. We find that color reconnection suppresses the relative production of meson resonances such as ρ0 and K* , providing an alternative explanation for the K*/K decrease observed in proton-proton collisions as a function of multiplicity by the ALICE collaboration. Detailed studies of the underlying mechanism causing meson resonance suppression indicate that color reconnection leads to shorter, less energetic strings whose fragmentation is less likely to produce more massive hadrons for a given quark content, therefore reducing ratios such as K*/K and ρ0/π in high-multiplicity pp collisions. In addition, we have also studied the effects of allowing string junctions to form and found that these may also contribute to resonance suppression.

  18. INFRARED LUMINOSITIES AND DUST PROPERTIES OF z ∼ 2 DUST-OBSCURED GALAXIES

    International Nuclear Information System (INIS)

    Bussmann, R. S.; Dey, Arjun; Jannuzi, B. T.; Borys, C.; Desai, V.; Sheth, K.; Soifer, B. T.; Le Floc'h, E.; Melbourne, J.

    2009-01-01

    We present SHARC-II 350 μm imaging of twelve 24 μm bright (F 24μm > 0.8 mJy) Dust-Obscured Galaxies (DOGs) and Combined Array for Research in Millimeter-wave Astronomy (CARMA) 1 mm imaging of a subset of two DOGs. These objects are selected from the Booetes field of the NOAO Deep Wide-Field Survey. Detections of four DOGs at 350 μm imply infrared (IR) luminosities which are consistent to within a factor of 2 of expectations based on a warm-dust spectral energy distribution (SED) scaled to the observed 24 μm flux density. The 350 μm upper limits for the 8 non-detected DOGs are consistent with both Mrk 231 and M82 (warm-dust SEDs), but exclude cold dust (Arp 220) SEDs. The two DOGs targeted at 1 mm were not detected in our CARMA observations, placing strong constraints on the dust temperature: T dust > 35-60 K. Assuming these dust properties apply to the entire sample, we find dust masses of ∼3 x 10 8 M sun . In comparison to other dusty z ∼ 2 galaxy populations such as submillimeter galaxies (SMGs) and other Spitzer-selected high-redshift sources, this sample of DOGs has higher IR luminosities (2 x 10 13 L sun versus 6 x 10 12 L sun for the other galaxy populations) that are driven by warmer dust temperatures (>35-60 K versus ∼30 K) and lower inferred dust masses (3 x 10 8 M sun versus 3 x 10 9 M sun ). Wide-field Herschel and Submillimeter Common-User Bolometer Array-2 surveys should be able to detect hundreds of these power-law-dominated DOGs. We use the existing Hubble Space Telescope and Spitzer/InfraRed Array Camera data to estimate stellar masses of these sources and find that the stellar to gas mass ratio may be higher in our 24 μm bright sample of DOGs than in SMGs and other Spitzer-selected sources. Although much larger sample sizes are needed to provide a definitive conclusion, the data are consistent with an evolutionary trend in which the formation of massive galaxies at z ∼ 2 involves a submillimeter bright, cold-dust, and star

  19. Dust-wall and dust-plasma interaction in the MIGRAINe code

    Science.gov (United States)

    Vignitchouk, L.; Tolias, P.; Ratynskaia, S.

    2014-09-01

    The physical models implemented in the recently developed dust dynamics code MIGRAINe are described. A major update of the treatment of secondary electron emission, stemming from models adapted to typical scrape-off layer temperatures, is reported. Sputtering and plasma species backscattering are introduced from fits of available experimental data and their relative importance to dust charging and heating is assessed in fusion-relevant scenarios. Moreover, the description of collisions between dust particles and plasma-facing components, based on the approximation of elastic-perfectly plastic adhesive spheres, has been upgraded to take into account the effects of particle size and temperature.

  20. Acute Lung Function Response to Dust in Street Sweepers

    OpenAIRE

    Johncy S., Smilee; G., Dhanyakumar; Samuel T., Vivian; K.T., Ajay; Bondade, Suresh Y.

    2013-01-01

    Background: Sweepers are chronically exposed to dust raised during sweeping. Dust is regarded as the most influential agent and it is perceived as a frequent cause of respiratory system illness and may cause acute and chronic lung function impairment.

  1. Dust cyclone technology for gins – A literature review

    Science.gov (United States)

    Dust cyclone research leading to more efficient designs has helped the cotton ginning industry to comply with increasingly stringent air quality regulations governing fine particulate emissions. Future changes in regulations may require additional improvements in dust cyclone efficacy. This inter-...

  2. Dust-gas interaction deduced from Halley multicolour camera observations

    International Nuclear Information System (INIS)

    Huebner, W.F.; Delamere, W.A.; Keller, H.U.; Reitsema, H.J.; Schmidt, H.U.; Whipple, F.L.; Wilhelm, K.

    1986-01-01

    The dust and gas productions of Comet Halley were measured by the dust counter and the mass spectrometers on the Giotto spacecraft. These instruments give only little information about the spatial asymmetry of the activity. The asymmetry in the dust production is clearly evident from the dust jets seen in the Halley Multicolour Camera images. Since the dust is entrained by the gas, production must be similarly asymmetric. The intensity profiles along and across several dust jets are related to their source regions on the nucleus. Properties of the dust jets are investigated. A few compact, but highly active source regions on the nucleus produce most of the visible dust and can account for most of the gas produced by the comet. 2 refs

  3. Dust removal from waste gas arising from fluidized beds

    International Nuclear Information System (INIS)

    Soltys, L.

    1992-01-01

    Two types dust removal equipment mostly useful for dust removal from waste gas from fluidized beds, i.e. electrofilters and pulsatory bag filters were presented. Their features and functional properties were compared. (author). 7 refs, 4 figs

  4. ULYSSES DUST DETECTION SYSTEM V3.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains the data from the Ulysses dust detector system (UDDS) from start of mission through the end of mission, 1990-2007. (As the dust detector was...

  5. Electrostatic dust detector for fusion devices with improved sensitivity

    International Nuclear Information System (INIS)

    Boyle, D.P.; Skinner, C.H.; Roquemore, A.L.

    2009-01-01

    Methods to measure the inventory of dust particles and to remove dust if it approaches safety limits will be required in next-step tokamaks such as ITER. An electrostatic dust detector, based on a fine grid of interlocking circuit traces, biased to 30 or 50 V, has been developed for the detection of dust on remote surfaces in air and vacuum environments. Gaining operational experience of dust detection on surfaces in tokamaks is important, however the level of dust generated in contemporary short-pulse tokamaks is comparatively low and high sensitivity is necessary to measure dust on a shot-by-shot basis. We report on modifications in the detection electronics that have increased the sensitivity of the electrostatic dust detector by a factor of up to 120, - a level suitable for measurements on contemporary tokamaks.

  6. Novel advanced methods of clearing air from fine dust

    OpenAIRE

    Batluk, V.; Proskurina, I.; Nadorshyn, Ye; Sheluh, Yu

    2007-01-01

    A completely new design of centrifugal inertial dust collector is proposed here its research allow to affirm that the efficiency of dust collecting increases for 10-12 % and powerand steel intensity decreases.

  7. Presentations at 2013 Pollinator Summit --Dust Focus Group

    Science.gov (United States)

    These presentations covered pesticide exposure risks posed to honey bees by the dust from planting treated corn seed, and research on reducing dust by means such as talc replacement and standards for planter technology.

  8. Durable Dust Repellent Coating for Metals, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The Durable Dust Repellent Coating (DDRC) consists of nano-phase silica, titania, or other oxide coatings to repel dust in a vacuum environment over a wide range of...

  9. Dust Mitigation for the Lunar Surface, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The lunar surface is to a large extent covered with a dust layer several meters thick. Known as lunar regolith, it poses a hazard in the form of dust clouds being...

  10. ULYSSES DUST DETECTION SYSTEM V3.1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains the data from the Ulysses dust detector system (UDDS) from start of mission through the end of mission, 1990-2007. (As the dust detector was...

  11. Dust in Snow in the Colorado River Basin: Spatial Variability in Dust Concentrations, Radiative Forcing, and Snowmelt Rates

    Science.gov (United States)

    Skiles, M.; Painter, T.; Deems, J. S.; Landry, C.; Bryant, A.

    2012-12-01

    Since the disturbance of the western US that began with the Anglo settlement in the mid 19th century, the mountain snow cover of the Colorado River Basin (CRB) has been subject to five-fold greater dust loading. This dust deposition accelerates snowmelt through its direct reduction of albedo and its further reduction of albedo by accelerating the growth of snow effective grain size. We have previously quantified the impacts of dust in snow using a 6-year record of dust concentration and energy balance fluxes at the alpine and subalpine towers in the Senator Beck Basin Study Area (SBBSA), San Juan Mountains in southwestern Colorado, USA. Dust loading exhibited interannual variability, and end of year dust concentrations were not necessarily related to the number of dust deposition events. Radiative forcing enhanced springtime melt by 21 to 51 days with the magnitude of advanced loss being linearly related to total dust concentration at the end of snow cover. To expand our understanding of dust on snow deposition patterns we utilize collections of dust concentration at the Colorado Dust on Snow (CODOS) study sites, established in 2009 along the western side of the CRB, to assess spatial variability in dust loading. In situ sampling of dust stratigraphy and concentration occurs twice each season, once over peak snow water equivalent (15 April), and again during melt (15 May). Dust loading occurs at all sites; dust concentrations are always higher in May, vary between sites, and the highest and lowest dust years were 2009 and 2012, respectively. In the absence of regular sampling and energy balance instrumentation these sites do not allow us to quantify the advanced melt due to dust. To facilitate this a new energy balance site, Grand Mesa Study plot (GMSP), was established for water year 2010 in west central Colorado, 150 km north of SBBSA. Back trajectories indicate similar Colorado Plateau dust sources at both SBBSA and GMSP, yet GMSP exhibits slightly lower dust

  12. Teaching to suppress Polglish processes

    OpenAIRE

    Dziubalska-Kołaczyk, Katarzyna; Balas, Anna; Schwartz, Geoffrey; Rojczyk, Arkadiusz; Wrembel, Magdalena

    2015-01-01

    Advanced second language (henceforth L2) learners in a formal setting can suppress many first language (henceforth L1) processes in L2 pronunciation when provided with sufficient exposure to L2 and meta competence (see Sect. 4 for a definition of this term). This paper shows how imitation in L2 teaching can be enhanced on the basis of current phonetic research and how complex allophonic processes such as nasal vocalization and glottal stop insertion can be suppressed using “repair”—a method o...

  13. Optical and microphysical properties of natural mineral dust and anthropogenic soil dust near dust source regions over northwestern China

    Science.gov (United States)

    Wang, Xin; Wen, Hui; Shi, Jinsen; Bi, Jianrong; Huang, Zhongwei; Zhang, Beidou; Zhou, Tian; Fu, Kaiqi; Chen, Quanliang; Xin, Jinyuan

    2018-02-01

    Mineral dust aerosols (MDs) not only influence the climate by scattering and absorbing solar radiation but also modify cloud properties and change the ecosystem. From 3 April to 16 May 2014, a ground-based mobile laboratory was deployed to measure the optical and microphysical properties of MDs near dust source regions in Wuwei, Zhangye, and Dunhuang (in chronological order) along the Hexi Corridor over northwestern China. Throughout this dust campaign, the hourly averaged (±standard deviation) aerosol scattering coefficients (σsp, 550 nm) of the particulates with aerodynamic diameters less than 2.5 µm (PM2.5) at these three sites were sequentially 101.5 ± 36.8, 182.2 ± 433.1, and 54.0 ± 32.0 Mm-1. Correspondingly, the absorption coefficients (σap, 637 nm) were 9.7 ± 6.1, 6.0 ± 4.6, and 2.3 ± 0.9 Mm-1; single-scattering albedos (ω, 637 nm) were 0.902 ± 0.025, 0.931 ± 0.037, and 0.949 ± 0.020; and scattering Ångström exponents (Åsp, 450-700 nm) of PM2.5 were 1.28 ± 0.27, 0.77 ± 0.51, and 0.52 ± 0.31. During a severe dust storm in Zhangye (i.e., from 23 to 25 April), the highest values of σsp2.5 ( ˜ 5074 Mm-1), backscattering coefficient (σbsp2.5, ˜ 522 Mm-1), and ω637 ( ˜ 0.993) and the lowest values of backscattering fraction (b2.5, ˜ 0.101) at 550 nm and Åsp2.5 ( ˜ -0.046) at 450-700 nm, with peak values of aerosol number size distribution (appearing at the particle diameter range of 1-3 µm), exhibited that the atmospheric aerosols were dominated by coarse-mode dust aerosols. It is hypothesized that the relatively higher values of mass scattering efficiency during floating dust episodes in Wuwei and Zhangye are attributed to the anthropogenic soil dust produced by agricultural cultivations.

  14. Pulmonary Toxicity Studies of Lunar Dusts in Rodents

    Science.gov (United States)

    Lam, Chiu-wing; James, John T.

    2009-01-01

    NASA will build an outpost on the lunar surface for long-duration human habitation and research. The surface of the Moon is covered by a layer of fine, reactive dust, and the living quarters in the lunar outpost are expected to be contaminated by lunar dust. Because the toxicity of lunar dust is not known, NASA has tasked its toxicology laboratory to evaluate the risk of exposure to the dust and to establish safe exposure limits for astronauts working in the lunar habitat. Studies of the pulmonary toxicity of a dust are generally done first in rodents by intratracheal/intrapharyngeal instillation. This toxicity screening test is then followed by an inhalation study, which requires much more of the test dust and is labor intensive. Preliminary results obtained by examining lung lavage fluid from dust-treated mice show that lunar dust was somewhat toxic (more toxic than TiO2, but less than quartz dust). More extensive studies are in progress to further examine lung lavage fluid for biomarkers of toxicity and lung tissues for histopathological lesions in rodents exposed to aged and activated (ground) lunar dust samples. In these studies, reference dusts (TiO2 and quartz) of known toxicities and have industrial exposure limits will be studied in parallel so the relative toxicity of lunar dust can be determined. The results from the instillation studies will be useful for choosing exposure concentrations for the animal inhalation study. The animal inhalation exposure will be conducted with lunar dust simulant prior to the study with the lunar dust. The experiment with the simulate will ensure that the study techniques used with actual lunar dust will be successful. The results of instillation and inhalation studies will reveal the toxicological risk of exposures and are essential for setting exposure limits on lunar dust for astronauts living in the lunar habitat.

  15. Immune Alterations in Rats Exposed to Airborne Lunar Dust

    Science.gov (United States)

    Crucian, Brian; Quiriarte, Heather; Nelman, Mayra; Lam, Chiu-wing; James, John T.; Sams, Clarence

    2014-01-01

    The lunar surface is covered by a layer of fine, reactive dust. Very little is known regarding the toxicity of lunar dust on human physiology. This study assessed the toxicity of airborne lunar dust exposure in rats on pulmonary and systemic immune parameters.

  16. Fine dust emissions in sandy and silty agricultural soils

    Science.gov (United States)

    Dust emissions from strong winds are common in arid and semi-arid regions and occur under both natural and managed land systems. A portable field wind tunnel has been developed to allow measurements of dust emissions from soil surfaces to test the premise that dust concentrations are highly correlat...

  17. Quantification of dust generating sources in gold and platinum mines.

    CSIR Research Space (South Africa)

    Biffi, M

    2003-03-01

    Full Text Available dust generation rates linked to activities presumed to be hazardous in this respect. The aim of this study was to identify prominent dust sources that occur in hard rock mines and to characterise these by means of on-site measurement of dust generations...

  18. Mineralogy of dust deposited during the Harmattan season in Ghana

    DEFF Research Database (Denmark)

    He, Changling; Breuning-Madsen, Henrik; Awadzi, Theodore W.

    2007-01-01

    In Ghana, a dust-laden Harmattan wind blows from the Sahara in the period November to March. Some of the dust is trapped in the vegetation, in lakes and other inland waters, and a little on the bare land, whereas the rest of the dust is blown further away to the Ivory Coast or out into the Atlant...

  19. Effect of nonthermal ion distribution and dust temperature on ...

    Indian Academy of Sciences (India)

    of coexistence of compressive as well as rarefactive solitary waves [4,5]. But, the dust tem- perature (which may not be negligible) was ignored [6–8]. Motivated by all the previous works, in this paper, we investigate dust-acoustic solitary waves, taking into account dust temperature as well as nonthermal ions and study their ...

  20. Nonplanar electrostatic shock waves in an opposite polarity dust ...

    Indian Academy of Sciences (India)

    M Amina

    2017-05-30

    May 30, 2017 ... The coexistence of positively and negatively charged dust grains has been observed in the Earth's mesosphere [11,12] as well as in cometary tails and comae [6]. The propagation of various types of nonlinear waves in dusty plasmas, viz., dust-acoustic (DA) waves [13], dust-ion-acoustic (DIA) waves [14,15] ...

  1. THREE-DIMENSIONAL DUST MAPPING REVEALS THAT ORION FORMS PART OF A LARGE RING OF DUST

    International Nuclear Information System (INIS)

    Schlafly, E. F.; Rix, H.-W.; Martin, N. F.; Green, G.; Finkbeiner, D. P.; Burgett, W. S.; Chambers, K. C.; Kaiser, N.; Morgan, J. S.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.; Draper, P. W.; Metcalfe, N.; Price, P. A.

    2015-01-01

    The Orion Molecular Complex is the nearest site of ongoing high-mass star formation, making it one of the most extensively studied molecular complexes in the Galaxy. We have developed a new technique for mapping the three-dimensional distribution of dust in the Galaxy using Pan-STARRS1 photometry. We isolate the dust at the distance to Orion using this technique, revealing a large (100 pc, 14° diameter), previously unrecognized ring of dust, which we term the ''Orion dust ring''. The ring includes Orion A and B, and is not coincident with current Hα features. The circular morphology suggests formation as an ancient bubble in the interstellar medium, though we have not been able to conclusively identify the source of the bubble. This hint at the history of Orion may have important consequences for models of high-mass star formation and triggered star formation

  2. Mold populations and dust mite allergen concentrations in house dust samples from across Puerto Rico.

    Science.gov (United States)

    Vesper, Stephen; Choi, Hyunok; Perzanowski, Matthew S; Acosta, Luis M; Divjan, Adnan; Bolaños-Rosero, Benjamin; Rivera-Mariani, Felix; Chew, Ginger L

    2016-01-01

    Lifetime childhood asthma prevalence (LCAP) percentages in Puerto Rico Health Regions (HR) are substantially higher in northeastern vs. southwestern HR. Higher average relative humidity in the northeast might promote mold and mite exposures and possibly asthma prevalence. To test this hypothesis, mold contamination, Environmental Relative Moldiness Index (ERMI) values were measured in floor dust (n = 26) and dust mite allergen concentrations in bed dust (n = 14). For this analysis, the eight HR were divided into those with LCAP > 30% (n = 3) and dust mite antigens Der p 1, Der f 1, and Blo t 5 were detected in 90% of bed samples, but the concentrations were not significantly different in high vs. low LCAP HR. Mold exposures might partially explain the differences in LCAP HR in Puerto Rico.

  3. THREE-DIMENSIONAL DUST MAPPING REVEALS THAT ORION FORMS PART OF A LARGE RING OF DUST

    Energy Technology Data Exchange (ETDEWEB)

    Schlafly, E. F.; Rix, H.-W.; Martin, N. F. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Green, G.; Finkbeiner, D. P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Burgett, W. S.; Chambers, K. C.; Kaiser, N.; Morgan, J. S.; Tonry, J. L.; Wainscoat, R. J.; Waters, C. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu HI 96822 (United States); Draper, P. W.; Metcalfe, N. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Price, P. A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2015-02-01

    The Orion Molecular Complex is the nearest site of ongoing high-mass star formation, making it one of the most extensively studied molecular complexes in the Galaxy. We have developed a new technique for mapping the three-dimensional distribution of dust in the Galaxy using Pan-STARRS1 photometry. We isolate the dust at the distance to Orion using this technique, revealing a large (100 pc, 14° diameter), previously unrecognized ring of dust, which we term the ''Orion dust ring''. The ring includes Orion A and B, and is not coincident with current Hα features. The circular morphology suggests formation as an ancient bubble in the interstellar medium, though we have not been able to conclusively identify the source of the bubble. This hint at the history of Orion may have important consequences for models of high-mass star formation and triggered star formation.

  4. 3D Dust Mapping Reveals that Orion Forms Part of a Large Ring of Dust

    Science.gov (United States)

    Ford Schlafly, Edward; Green, Gregory; Finkbeiner, Douglas P.; Rix, Hans-Walter

    2015-01-01

    The Orion Molecular Complex is the nearest site of ongoing high-mass star formation, making it one of the most extensively studied molecular complexes in the Galaxy. We have developed a new technique for mapping the 3D distribution of dust in the Galaxy using Pan-STARRS1 photometry. We isolate the dust at the distance to Orion using this technique, revealing a large (100 pc, 14° diameter), previously unrecognized ring of dust, which we term the "Orion dust ring." The ring includes Orion A and B, and is not coincident with current Hα features. The circular morphology suggests formation as an ancient bubble in the interstellar medium, though we have not been able to conclusively identify the source of the bubble. This hint at the history of Orion may have important consequences for models of high-mass star formation and triggered star formation.

  5. Interstellar dust. Evidence for interstellar origin of seven dust particles collected by the Stardust spacecraft.

    Science.gov (United States)

    Westphal, Andrew J; Stroud, Rhonda M; Bechtel, Hans A; Brenker, Frank E; Butterworth, Anna L; Flynn, George J; Frank, David R; Gainsforth, Zack; Hillier, Jon K; Postberg, Frank; Simionovici, Alexandre S; Sterken, Veerle J; Nittler, Larry R; Allen, Carlton; Anderson, David; Ansari, Asna; Bajt, Saša; Bastien, Ron K; Bassim, Nabil; Bridges, John; Brownlee, Donald E; Burchell, Mark; Burghammer, Manfred; Changela, Hitesh; Cloetens, Peter; Davis, Andrew M; Doll, Ryan; Floss, Christine; Grün, Eberhard; Heck, Philipp R; Hoppe, Peter; Hudson, Bruce; Huth, Joachim; Kearsley, Anton; King, Ashley J; Lai, Barry; Leitner, Jan; Lemelle, Laurence; Leonard, Ariel; Leroux, Hugues; Lettieri, Robert; Marchant, William; Ogliore, Ryan; Ong, Wei Jia; Price, Mark C; Sandford, Scott A; Sans Tresseras, Juan-Angel; Schmitz, Sylvia; Schoonjans, Tom; Schreiber, Kate; Silversmit, Geert; Solé, Vicente A; Srama, Ralf; Stadermann, Frank; Stephan, Thomas; Stodolna, Julien; Sutton, Stephen; Trieloff, Mario; Tsou, Peter; Tyliszczak, Tolek; Vekemans, Bart; Vincze, Laszlo; Von Korff, Joshua; Wordsworth, Naomi; Zevin, Daniel; Zolensky, Michael E

    2014-08-15

    Seven particles captured by the Stardust Interstellar Dust Collector and returned to Earth for laboratory analysis have features consistent with an origin in the contemporary interstellar dust stream. More than 50 spacecraft debris particles were also identified. The interstellar dust candidates are readily distinguished from debris impacts on the basis of elemental composition and/or impact trajectory. The seven candidate interstellar particles are diverse in elemental composition, crystal structure, and size. The presence of crystalline grains and multiple iron-bearing phases, including sulfide, in some particles indicates that individual interstellar particles diverge from any one representative model of interstellar dust inferred from astronomical observations and theory. Copyright © 2014, American Association for the Advancement of Science.

  6. "Kicking Up Some Dust": An Experimental Investigation Relating Lunar Dust Erosive Wear to Solar Power Loss

    Science.gov (United States)

    Mpagazehe, Jeremiah N.; Street, Kenneth W., Jr.; Delgado, Irebert R.; Higgs, C. Fred, III

    2013-01-01

    The exhaust from retrograde rockets fired by spacecraft landing on the Moon can accelerate lunar dust particles to high velocities. Information obtained from NASA's Apollo 12 mission confirmed that these high-speed dust particles can erode nearby structures. This erosive wear damage can affect the performance of optical components such as solar concentrators. Solar concentrators are objects which collect sunlight over large areas and focus the light into smaller areas for purposes such as heating and energy production. In this work, laboratory-scale solar concentrators were constructed and subjected to erosive wear by the JSC-1AF lunar dust simulant. The concentrators were focused on a photovoltaic cell and the degradation in electrical power due to the erosive wear was measured. It was observed that even moderate exposure to erosive wear from lunar dust simulant resulted in a 40 percent reduction in power production from the solar concentrators.

  7. Computer simulation of dust grain evolution

    Science.gov (United States)

    Liffman, K.

    1989-01-01

    The latest results are reported from a Monte Carlo code that is being developed at NASA Ames. The goal of this program, is to derive from the observed and presumed properties of the interstellar medium (ISM) the following information: (1) the size spectrum of interstellar dust; (2) the chemical structure of interstellar dust; (3) interstellar abundances; and (4) the lifetime of a dust grain in the ISM. Presently this study is restricted to refractory interstellar material, i.e., the formation and destruction of ices are not included in the program. The program is embedded in an analytic solution for the bulk chemical evolution of a two-phase interstellar medium in which stars are born in molecular clouds, but new nucleosynthesis products and stellar return are entered into a complementary intercloud medium. The well-mixed matter of each interstellar phase is repeatedly cycled stochastically through the complementary phase and back. Refractory dust is created by thermal condensation as stellar matter flows away from sites of nucleosynthesis such as novae and supernovae and/or from the matter returned from evolved intermediate stars. The history of each particle is traced by standard Monte Carlo techniques as it is sputtered and fragmented by supernova shock waves in the intercloud medium. It also accretes an amorphous mantle of gaseous refractory atoms when its local medium joins with the molecular cloud medium. Finally it encounters the possibility of astration (destruction by star formation) within the molecular clouds.

  8. Electrostatic dust detection on remote surfaces

    International Nuclear Information System (INIS)

    Voinier, C.; Skinner, C.H.; Roquemore, A.L.

    2005-01-01

    The inventory of dust in next-step magnetic fusion devices will be regulated for safety reasons, however diagnostics to measure in-vessel dust are still in their infancy. Advances in dust particle detection on remote surfaces are reported. Grids of interlocking circuit traces with spacing in the range 125-25 μm were biased to 30 V. Impinging dust creates a short circuit and the resulting current pulse was recorded. The detector response was measured with particles scraped from a carbon fiber composite tile and sorted by size category. The finest 25 μm grid showed a sensitivity more than an order of magnitude higher than the 125 μm grid. The response to the finest particle categories (5-30 μm) was two orders of magnitude higher than the largest (125-250 μm) category. Longer duration current pulses were observed from the coarser particles. The results indicate a detection threshold for fine particles below 1 μg/cm 2

  9. Dust-Firing of Straw and Additives

    DEFF Research Database (Denmark)

    Wu, Hao; Glarborg, Peter; Frandsen, Flemming

    2011-01-01

    In the present work, the ash chemistry and deposition behavior during straw dust-firing were studied by performing experiments in an entrained flow reactor. The effect of using spent bleaching earth (SBE) as an additive in straw combustion was also investigated by comparing with kaolinite. During...

  10. Cyclo nic separation of uranate dust

    International Nuclear Information System (INIS)

    Nadal, P.

    1976-01-01

    Size of particles of uranate dust which can be entrained by hot gases leaving a multiple-hearth furnace is determined. The convenience of the installation of a cyclone is discussed considering power of the fume-extractor and pressure-drop permissible in the system. (Author)

  11. The carbohydrate moiety of house dust allergen

    NARCIS (Netherlands)

    Morris, J.H.; Berrens, L.; Young, E.

    1965-01-01

    Purified house dust allergen has been found to contain monosaccharides of plant and animal origin, and has been partially fractionated by DEAE-Sephadex column chromatography. The carbohydrate is highly branched, suffering little attack during periodate oxidation. Furanose configuration for a

  12. House dust mite control measures for asthma

    DEFF Research Database (Denmark)

    Gøtzsche, Peter C.; Johansen, Helle Krogh

    2008-01-01

    antigens in the homes of people with mite-sensitive asthma. SEARCH STRATEGY: PubMed and The Cochrane Library (last searches Nov 2007), reference lists. SELECTION CRITERIA: Randomised trials of mite control measures vs placebo or no treatment in people with asthma known to be sensitive to house dust mites...

  13. Bioleaching of metals from WEEE shredding dust.

    Science.gov (United States)

    Marra, Alessandra; Cesaro, Alessandra; Rene, Eldon R; Belgiorno, Vincenzo; Lens, Piet N L

    2018-03-15

    A bioleaching process developed in two separate steps was investigated for the recovery of base metals, precious metals and rare earth elements from dusts generated by Waste Electrical and Electronic Equipment (WEEE) shredding. In the first step, base metals were almost completely leached from the dust in 8 days by Acidithiobacillus thiooxidans (DSM 9463) that lowered the pH of the leaching solution from 3.5 to 1.0. During this step, cerium, europium and neodymium were mobilized at high percentages (>99%), whereas lanthanum and yttrium reached an extraction yield of 80%. In the second step, the cyanide producing Pseudomonas putida WSC361 mobilized 48% of gold within 3 h from the A. thiooxidans leached shredding dust. This work demonstrated the potential application of biohydrometallurgy for resource recovery from WEEE shredding dust, destined to landfill disposal, and its effectiveness in the extraction of valuable substances, including elements at high supply risk as rare earths. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Dust properties in the Galactic bulge

    NARCIS (Netherlands)

    Pottasch, S. R.; Bernard-Salas, J.

    Context. It has been suggested that the ratio of total-to-selective extinction R-V in dust in the interstellar medium differs in the Galactic bulge from its value in the local neighborhood. Aims. We attempt to test this suggestion. Methods. The mid-infrared hydrogen lines in 16 Galactic bulge PNe

  15. [Petrological Analysis of Astrophysical Dust Analog Evolution

    Science.gov (United States)

    Rietmeijer, Frans J. M.

    1997-01-01

    This project "Petrological analysis of astrophysical dust analog evolution" was initiated to try to understand the vapor phase condensation, and the nature of the reaction products, in circumstellar environments, such as the solar nebula 4,500 Myrs ago, and in the interstellar medium. Telescope-based infrared [IR] spectroscopy offers a broad-scale inventory of the various types of dust in these environments but no details on small-scale variations in terms of chemistry and morphology and petrological phase relationships. Vapor phase condensation in these environments is almost certainly a non-equilibrium process. The main challenge to this research was to document the nature of this process that, based on astrophysical observations, seems to yield compositionally consistent materials. This observation may suggest a predictable character during non-equilibrium condensation. These astrophysical environments include two chemically distinct, that is, oxygen-rich and carbon-rich environments. The former is characterized by silicates the latter by carbon-bearing solids. According to cosmological models of stellar evolution circumstellar dust accreted into protoplanets wherein thermal and/or aqueous processes will alter the dust under initially, non-equilibrium conditions.

  16. IONIZATION AND DUST CHARGING IN PROTOPLANETARY DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Ivlev, A. V.; Caselli, P. [Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstr. 1, D-85748 Garching (Germany); Akimkin, V. V., E-mail: ivlev@mpe.mpg.de [Institute of Astronomy of the Russian Academy of Sciences, Pyatnitskaya Street 48, 119017 Moscow (Russian Federation)

    2016-12-10

    Ionization–recombination balance in dense interstellar and circumstellar environments is a key factor for a variety of important physical processes, such as chemical reactions, dust charging and coagulation, coupling of the gas with magnetic field, and development of instabilities in protoplanetary disks. We determine a critical gas density above which the recombination of electrons and ions on the grain surface dominates over the gas-phase recombination. For this regime, we present a self-consistent analytical model, which allows us to calculate exactly the abundances of charged species in dusty gas, without making assumptions on the grain charge distribution. To demonstrate the importance of the proposed approach, we check whether the conventional approximation of low grain charges is valid for typical protoplanetary disks, and discuss the implications for dust coagulation and development of the “dead zone” in the disk. The presented model is applicable for arbitrary grain-size distributions and, for given dust properties and conditions of the disk, has only one free parameter—the effective mass of the ions, shown to have a small effect on the results. The model can be easily included in numerical simulations following the dust evolution in dense molecular clouds and protoplanetary disks.

  17. Computer simulation of dust grain evolution

    International Nuclear Information System (INIS)

    Liffman, K.

    1989-01-01

    The latest results are reported from a Monte Carlo code that is being developed at NASA Ames. The goal of this program, is to derive from the observed and presumed properties of the interstellar medium (ISM) the following information: (1) the size spectrum of interstellar dust; (2) the chemical structure of interstellar dust; (3) interstellar abundances; and (4) the lifetime of a dust grain in the ISM. Presently this study is restricted to refractory interstellar material, i.e., the formation and destruction of ices are not included in the program. The program is embedded in an analytic solution for the bulk chemical evolution of a two-phase interstellar medium in which stars are born in molecular clouds, but new nucleosynthesis products and stellar return are entered into a complementary intercloud medium. The well-mixed matter of each interstellar phase is repeatedly cycled stochastically through the complementary phase and back. Refractory dust is created by thermal condensation as stellar matter flows away from sites of nucleosynthesis such as novae and supernovae and/or from the matter returned from evolved intermediate stars. The history of each particle is traced by standard Monte Carlo techniques as it is sputtered and fragmented by supernova shock waves in the intercloud medium. It also accretes an amorphous mantle of gaseous refractory atoms when its local medium joins with the molecular cloud medium. Finally it encounters the possibility of astration (destruction by star formation) within the molecular clouds

  18. Composition, structure and chemistry of interstellar dust

    International Nuclear Information System (INIS)

    Tielens, A.G.G.M.; Allamandola, L.J.

    1986-09-01

    The observational constraints on the composition of the interstellar dust are analyzed. The dust in the diffuse interstellar medium consists of a mixture of stardust (amorphous silicates, amorphous carbon, polycyclic aromatic hydrocarbons, and graphite) and interstellar medium dust (organic refractory material). Stardust seems to dominate in the local diffuse interstellar medium. Inside molecular clouds, however, icy grain mantles are also important. The structural differences between crystalline and amorphous materials, which lead to differences in the optical properties, are discussed. The astrophysical consequences are briefly examined. The physical principles of grain surface chemistry are discussed and applied to the formation of molecular hydrogen and icy grain mantles inside dense molecular clouds. Transformation of these icy grain mantles into the organic refractory dust component observed in the diffuse interstellar medium requires ultraviolet sources inside molecular clouds as well as radical diffusion promoted by transient heating of the mantle. The latter process also returns a considerable fraction of the molecules in the grain mantle to the gas phase

  19. Dust in Protoplanetary Disks: Properties and Evolution

    NARCIS (Netherlands)

    Natta, A.; Testi, L.; Calvet, N.; Henning, T.; Waters, R.; Wilner, D.

    2007-01-01

    We review the properties of dust in protoplanetary disks around optically visible pre-main-sequence stars obtained with a variety of observational techniques, from measurements of scattered light at visual and infrared wavelengths to mid-infrared spectroscopy and millimeter interferometry. A general

  20. Metal dusting: kinetically or thermodynamically controlled?

    NARCIS (Netherlands)

    Hermse, C.G.M.

    2011-01-01

    The current paper determines whether the rate of the metal dusting reaction is kinetically or thermodynamically controlled at 600 degrees Celsius. This is done by varying the gas composition, specifically the CO partial pressure and the carbon activity, and comparing the degradation rates of alloy

  1. Physical properties of suspended dust in Iceland

    Czech Academy of Sciences Publication Activity Database

    Dagsson-Waldhauserova, P.; Olafsson, H.; Arnalds, O.; Škrabalová, L.; Sigurdardottir, G.; Braniš, M.; Hladil, Jindřich; Chadimová, Leona; Navrátil, Tomáš; von Lowis of Menar, S.; Thorsteinsson, T.

    2014-01-01

    Roč. 16, - (2014), s. 8565-8565 ISSN 1607-7962. [European Geosciences Union General Assembly. 27.04.2014-02.05.2014, Vienna] Institutional support: RVO:67985831 Keywords : dust * volcanology * Iceland http://meetingorganizer.copernicus.org/EGU2014/EGU2014-8565.pdf

  2. Chemical desorption and diffusive dust chemistry

    NARCIS (Netherlands)

    Dulieu, Francois; Pirronello, Valerio; Minissale, Marco; Congiu, Emanuele; Baouche, Saoud; Chaabouni, Henda; Moudens, Audrey; Accolla, Mario; Cazaux, Stephanie; Manicò, Giulio

    2014-01-01

    In molecular clouds, gaseous species can accrete efficiently on the cold surfaces of dust grains. As for radical-radical reactions, the surface of the grains acts as a third body, and changes dramatically the efficiency of the reactions (i.e., H2 formation), or lowers considerably the barrier to

  3. Linear Alkylbenzenesulfonates in indoor Floor Dust

    DEFF Research Database (Denmark)

    Madsen, Jørgen Øgaard; Wolkoff, Peder; Madsen, Jørgen Øgaard

    1999-01-01

    LAS/g. The analysis of the office dust samples indicated that LAS (and probably other tensides) might be of importance for the indoor environment. However, more knowledge is required about how low concentrations of surface-active agents in combination with other compounds may affect the eye tear film...

  4. Dust Load on Surfaces in Animal Buildings

    DEFF Research Database (Denmark)

    Lengweiler, P.; Strøm, J. S.; Takai, H.

    To investigate the physical process of particle deposition on and resuspension from surfaces in animal buildings, a test facility and a sampling method is established. The influences of surface orientation and air turbulence and velocity just as other parameters on the dust load on a surface...

  5. Spherically symmetric inhomogeneous dust collapse in higher ...

    Indian Academy of Sciences (India)

    We consider a collapsing spherically symmetric inhomogeneous dust cloud in higher dimensional space-time. ... The existence of strong curvature naked singularities in gravitational collapse of spherically symmetric space-times ... where an over dot denotes partial derivative with respect to t. The functions F(r) and f(r).

  6. Interstellar Chemistry : Radiation, Dust and Metals

    NARCIS (Netherlands)

    Spaans, Marco; Hunt, LK; Madden, S; Schneider, R

    2008-01-01

    An overview is given of the chemical processes that; occur in primordial systems under the influence of radiation. metal abundances and dust, surface reactions. It is found that radiative feedback effects differ for UV and X-ray photons at any metallicity, with molecules surviving quite well under

  7. Conditioned suppression, punishment, and aversion

    Science.gov (United States)

    Orme-Johnson, D. W.; Yarczower, M.

    1974-01-01

    The aversive action of visual stimuli was studied in two groups of pigeons which received response-contingent or noncontingent electric shocks in cages with translucent response keys. Presentation of grain for 3 sec, contingent on key pecking, was the visual stimulus associated with conditioned punishment or suppression. The responses of the pigeons in three different experiments are compared.

  8. Plasma suppression of beamstrahlung: Revision

    International Nuclear Information System (INIS)

    Whittum, D.H.; Sessler, A.M.; Stewart, J.J.; Yu, S.S.

    1988-06-01

    We investigate the use of a plasma at the interaction point of two colliding beams to suppress beamstrahlung and related phenomena. We derive conditions for good current cancellation via plasma return currents and report on numerical simulations conducted to confirm our analytic results. 17 refs., 5 figs., 5 tabs

  9. Effect of dust size distribution on ion-acoustic solitons in dusty plasmas with different dust grains

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Dong-Ning; Yang, Yang; Yan, Qiang [Northwest Normal University, College of Physics and Electronic Engineering (China); Wang, Xiao-Yun [Lanzhou Jiao Tong University, Department of Mathematics and Physics (China); Duan, Wen-Shan, E-mail: duanws@126.com [Northwest Normal University, College of Physics and Electronic Engineering (China)

    2017-02-15

    Theoretical studies are carried out for ion acoustic solitons in multicomponent nonuniform plasma considering the dust size distribution. The Korteweg−de Vries equation for ion acoustic solitons is given by using the reductive perturbation technique. Two special dust size distributions are considered. The dependences of the width and amplitude of solitons on dust size parameters are shown. It is found that the properties of a solitary wave depend on the shape of the size distribution function of dust grains.

  10. Rutin suppresses atopic dermatitis and allergic contact dermatitis.

    Science.gov (United States)

    Choi, Jin Kyeong; Kim, Sang-Hyun

    2013-04-01

    Atopic dermatitis (AD) and allergic contact dermatitis (ACD) is a common allergic inflammatory skin disease caused by a combination of eczematous, scratching, pruritus and cutaneous sensitization with allergens. The aim of our study was to examine whether rutin, a predominant flavonoid having anti-inflammatory and antioxidative potential, modulates AD and ACD symptoms. We established an atopic dermatitis model in BALB/c mice by repeated local exposure of house dust mite (Dermatophagoides farinae) extract (DFE) and 2,4-dinitrochlorobenzene (DNCB) to the ears. In addition, 2,4-dinitroflourobenzene-sensitized a local lymph node assay was used for the ACD model. Repeated alternative treatment of DFE/DNCB caused AD symptoms. Topical application of rutin reduced AD based on ear thickness and histopathological analysis, in addition to serum IgE levels. Rutin inhibited mast cell infiltration into the ear and serum histamine level. Rutin suppressed DFE/DNCB-induced expression of interleukin (IL)-4, IL-5, IL-13, IL-31, IL-32 and interferon (INF)-γ in the tissue. In addition, rutin suppressed ACD based on ear thickness and lymphocyte proliferation, serum IgG2a levels, and expression of INF-γ, IL-4, IL-5, IL-10, IL-17 and tumour necrosis factor-α in ACD ears. This study demonstrates that rutin inhibits AD and ACD, suggesting that rutin might be a candidate for the treatment of allergic skin diseases.

  11. Salvia plebeia suppresses atopic dermatitis-like skin lesions.

    Science.gov (United States)

    Choi, Jin Kyeong; Oh, Hyun-Mee; Lee, Soyoung; Kwon, Taeg Kyu; Shin, Tae-Yong; Rho, Mun-Chual; Kim, Sang-Hyun

    2014-01-01

    Salvia plebeia R. Br. (Lamiaceae) has been used for folk medicines in Asian countries, including Korea and China, to treat skin inflammatory diseases and asthma. In this study, we investigated the effects of S. plebeia extract (SPE) on atopic dermatitis (AD)-like skin lesions and defined underlying mechanisms of action. We established an AD model in BALB/c mice by repeated local exposure of house dust mite extract (Dermatophagoides farinae extract, DFE) and 2,4-dinitrochlorobenzene (DNCB) to the ears. Repeated alternative treatment of DFE/DNCB caused AD-like skin lesions. The oral administration of SPE decreased AD symptoms based on ear thickness and histopathological analysis, in addition to serum IgE and IgG2a levels. SPE suppressed mast cell infiltration into the ear and serum histamine level. SPE inhibited Th1/Th2/Th17 phenotype CD4(+) T lymphocytes expansion in the lymph node and the expression of Th1/Th2/Th17 cytokines in the ear tissue. To define the underlying mechanisms of action, the tumor necrosis factor (TNF)-α and interferon (IFN)-γ activated human keratinocytes (HaCaT) model was used. SPE significantly suppressed the expression of cytokines and chemokines through the down-regulation of mitogen-activated protein kinases, nuclear factor-κB, and STAT1 in HaCaT cells. Taken together, our results suggest that SPE might be a candidate for the treatment of AD.

  12. Planar dust-acoustic waves in electron–positron–ion–dust plasmas ...

    Indian Academy of Sciences (India)

    2014-09-19

    Sep 19, 2014 ... ever, Xue [19] and Tarsem et al [20] proved that the observed wave phenomena in the low-altitude and .... tot. ∫ amax amin a−β da, β is the power-law index. n(a) = 0 when aamax. If the dust grain size a<λDd, the mass of the dust grain can be given as mdj = kma3 j. , where km ≈ 4. 3 πρd (ρd is ...

  13. Quantitation of house dust mites and house dust mite allergens in the microenvironment of dogs.

    Science.gov (United States)

    Randall, Amy; Hillier, Andrew; Cole, Lynette K; Kwochka, Kenneth W; Needham, Glen; Wassom, Donald L

    2003-10-01

    To quantitate the density of Dermatophagoides farinae and D pteronyssinus and concentrations of house dust mite (HDM) allergens (Der f 1, Der p 1, and Group 2 allergens) in the indoor microenvironment of dogs. Sample Population-50 homes in Columbus, Ohio. n each home, samples of dust were collected from 3 locations in which dogs spent most time. Whenever possible, the species of mites collected was identified. Mite density (mites/g of dust) was assessed, and allergen concentrations were assayed by standardized ELISAs. Relative humidity and temperature in each home were monitored during a 5-day period. Characteristics of homes and sample sources were evaluated. Dust samples from all 50 homes contained > or = 1 HDM allergen; Der f 1 and Der p 1 were detected in 100 and 74% of homes, respectively. Fifteen homes had HDMs; compared with D pteronyssinus, D farinae was found more commonly (14/15 homes) and at a higher density. Basements, homes without central air-conditioning, and dog beds that were > or = 1 year old had high HDM allergen concentrations. Homes with > or = 2 microg of Der f 1 or Group 2 allergens/g of dust or > or = 100 mites/g of dust were significantly more likely to have a maximum relative humidity > or = 75%. Results indicate the presence of HDMs and HDM allergens in the specific microenvironment of dogs in homes. Factors associated with high levels of exposure were identified, which may be associated with increased risk for sensitization and development of atopic diseases.

  14. Universal instability of dust ion-sound waves and dust-acoustic waves

    International Nuclear Information System (INIS)

    Tsytovich, V.N.; Watanabe, K.

    2002-01-01

    It is shown that the dust ion-sound waves (DISW) and the dust-acoustic waves (DAW) are universally unstable for wave numbers less than some critical wave number. The basic dusty plasma state is assumed to be quasi-neutral with balance of the plasma particle absorption on the dust particles and the ionization with the rate proportional to the electron density. An analytical expression for the critical wave numbers, for the frequencies and for the growth rates of DISW and DAW are found using the hydrodynamic description of dusty plasma components with self-consistent treatment of the dust charge variations and by taking into account the change of the ion and electron distributions in the dust charging process. Most of the previous treatment do not take into account the latter process and do not treat the basic state self-consistently. The critical lengths corresponding to these critical wave numbers can be easily achieved in the existing experiments. It is shown that at the wave numbers larger than the critical ones DISW and DAW have a large damping which was not treated previously and which can be also measured. The instabilities found in the present work on their non linear stage can lead to formation of different types of dust self-organized structures. (author)

  15. The Dust Management Project: Characterizing Lunar Environments and Dust, Developing Regolith Mitigation Technology and Simulants

    Science.gov (United States)

    Hyatt, Mark J.; Straka, Sharon A.

    2010-01-01

    A return to the Moon to extend human presence, pursue scientific activities, use the Moon to prepare for future human missions to Mars, and expand Earth?s economic sphere, will require investment in developing new technologies and capabilities to achieve affordable and sustainable human exploration. From the operational experience gained and lessons learned during the Apollo missions, conducting long-term operations in the lunar environment will be a particular challenge, given the difficulties presented by the unique physical properties and other characteristics of lunar regolith, including dust. The Apollo missions and other lunar explorations have identified significant lunar dust-related problems that will challenge future mission success. Comprised of regolith particles ranging in size from tens of nanometers to microns, lunar dust is a manifestation of the complex interaction of the lunar soil with multiple mechanical, electrical, and gravitational effects. The environmental and anthropogenic factors effecting the perturbation, transport, and deposition of lunar dust must be studied in order to mitigate it?s potentially harmful effects on exploration systems and human explorers. The Dust Management Project (DMP) is tasked with the evaluation of lunar dust effects, assessment of the resulting risks, and development of mitigation and management strategies and technologies related to Exploration Systems architectures. To this end, the DMP supports the overall goal of the Exploration Technology Development Program (ETDP) of addressing the relevant high priority technology needs of multiple elements within the Constellation Program (CxP) and sister ETDP projects. Project scope, plans, and accomplishments will be presented.

  16. THE DUST BUDGET OF THE SMALL MAGELLANIC CLOUD: ARE ASYMPTOTIC GIANT BRANCH STARS THE PRIMARY DUST SOURCE AT LOW METALLICITY?

    International Nuclear Information System (INIS)

    Boyer, M. L.; Gordon, K. D.; Meixner, M.; Sargent, B. A.; Srinivasan, S.; Riebel, D.; McDonald, I.; Van Loon, J. Th.; Clayton, G. C.; Sloan, G. C.

    2012-01-01

    We estimate the total dust input from the cool evolved stars in the Small Magellanic Cloud, using the 8 μm excess emission as a proxy for the dust-production rate (DPR). We find that asymptotic giant branch (AGB) and red supergiant (RSG) stars produce (8.6-9.5) × 10 –7 M ☉ yr –1 of dust, depending on the fraction of far-infrared sources that belong to the evolved star population (with 10%-50% uncertainty in individual DPRs). RSGs contribute the least ( –3 M ☉ of dust each, then the total SN dust input and AGB input are roughly equivalent. We consider several scenarios of SN dust production and destruction and find that the interstellar medium (ISM) dust can be accounted for solely by stellar sources if all SNe produce dust in the quantities seen around the dustiest examples and if most SNe explode in dense regions where much of the ISM dust is shielded from the shocks. We find that AGB stars contribute only 2.1% of the ISM dust. Without a net positive contribution from SNe to the dust budget, this suggests that dust must grow in the ISM or be formed by another unknown mechanism.

  17. Model Study on the Transport and Mixing of Dust Aerosols and Pollutants during an Asian Dust Storm in March 2002

    Directory of Open Access Journals (Sweden)

    Xiujuan Zhao

    2007-01-01

    Full Text Available The transport and mixing of dust aerosols and pollutants in East Asia during March 18 to 22, 2002 was studied using the nested air quality prediction model system (NAQPMS. Dust was primarily generated in the Gobi desert on 19 March and then swept across several areas of East Asia. The model results were verified with observations of surface weather, TSP/PM10, SO2 and lidar data. The model simulated the right timing and strength of dust events, capturing most of the variation features in dust and SO2. Numerical results showed that the dust aerosols were mainly transported in two layers and mixed with pollutants in different ways. Some of the dust kicked up in the source region was uplifted to a higher layer (200 - 2000 m layer and transported downwind faster than dust of the lower level. This lower-level dust was of greater concentration. The dust arriving at the upper layer began to drop and mixed well with pollutants in the atmosphere during ¡§the first period¡¨. During ¡§the second period¡¨, pollutants were diluted by the dust air mass that was transported along the lower layer. The remaining pollutants mixed well with dust aerosols during this period. The mixed air mass of the higher layer (1500 m eventually reached the Northwestern Pacific. A large amount of clouds in the upper layers potentially led to an increase in sulfate mass on the surface of dust particles.

  18. Model Study on the Transport and Mixing of Dust Aerosols and Pollutants during an Asian Dust Storm in March 2002

    Directory of Open Access Journals (Sweden)

    Xiujuan Zhao

    2007-01-01

    Full Text Available The transport and mixing of dust aerosols and pollutants in East Asia during March 18 to 22, 2002 was studied using the nested air quality prediction model system (NAQPMS. Dust was primarily generated in the Gobi desert on 19 March and then swept across several areas of East Asia. The model results were verified with observations of surface weather, TSP/PM10, SO2 and lidar data. The model simulated the right timing and strength of dust events, capturing most of the variation features in dust and SO2. Numerical results showed that the dust aerosols were mainly transported in two layers and mixed with pollutants in different ways. Some of the dust kicked up in the source region was uplifted to a higher layer (200 - 2000 m layer and transported downwind faster than dust of the lower level. This lower-level dust was of greater concentration. The dust arriving at the upper layer began to drop and mixed well with pollutants in the atmosphere during _ first _ During _ second _ pollutants were diluted by the dust air mass that was transported along the lower layer. The remaining pollutants mixed well with dust aerosols during this period. The mixed air mass of the higher layer (1500 m eventually reached the Northwestern Pacific. A large amount of clouds in the upper layers potentially led to an increase in sulfate mass on the surface of dust particles.

  19. 42 CFR 84.1145 - Silica dust test; non-powered single-use dust respirators; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... RESPIRATORY PROTECTIVE DEVICES Dust, Fume, and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1145 Silica dust test; non-powered single-use dust... shall be used. (c) Air exhaled through the respirator will be 35° ±2 °C. with 94 ±3 percent relative...

  20. Cosmic dust in the earth's atmosphere

    Science.gov (United States)

    Plane, John M. C.

    2012-04-01

    This review discusses the magnitude of the cosmic dust input into the earth's atmosphere, and the resulting impacts from around 100 km to the earth's surface. Zodiacal cloud observations and measurements made with a spaceborne dust detector indicate a daily mass input of interplanetary dust particles ranging from 100 to 300 tonnes, which is in agreement with the accumulation rates of cosmic-enriched elements (Ir, Pt, Os and super-paramagnetic Fe) in polar ice cores and deep-sea sediments. In contrast, measurements in the middle atmosphere - by radar, lidar, high-flying aircraft and satellite remote sensing - indicate that the input is between 5 and 50 tonnes per day. There are two reasons why this huge discrepancy matters. First, if the upper range of estimates is correct, then vertical transport in the middle atmosphere must be considerably faster than generally believed; whereas if the lower range is correct, then our understanding of dust evolution in the solar system, and transport from the middle atmosphere to the surface, will need substantial revision. Second, cosmic dust particles enter the atmosphere at high speeds and undergo significant ablation. The resulting metals injected into the atmosphere are involved in a diverse range of phenomena, including: the formation of layers of metal atoms and ions; the nucleation of noctilucent clouds, which are a sensitive marker of climate change; impacts on stratospheric aerosols and O3 chemistry, which need to be considered against the background of a cooling stratosphere and geo-engineering plans to increase sulphate aerosol; and fertilization of the ocean with bio-available Fe, which has potential climate feedbacks.