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Literatura académica sobre el tema "Atmospheric deposits"

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Publicado: 25 de mayo de 2024

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Artículos de revistas sobre el tema "Atmospheric deposits"

Skarżyńska, K., Ż. Polkowska y J. Namieśnik. "Sampling of Atmospheric Precipitation and Deposits for Analysis of Atmospheric Pollution". Journal of Automated Methods and Management in Chemistry 2006 (2006): 1–19. http://dx.doi.org/10.1155/jammc/2006/26908.

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This paper reviews techniques and equipment for collecting precipitation samples from the atmosphere (fog and cloud water) and from atmospheric deposits (dew, hoarfrost, and rime) that are suitable for the evaluation of atmospheric pollution. It discusses the storage and preparation of samples for analysis and also presents bibliographic information on the concentration ranges of inorganic and organic compounds in the precipitation and atmospheric deposit samples.

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Kim, Jiyoung, Chan Hee Lee, Ran Hee Kim y Eun Jeong Shin. "Characterization of White and Black Deposits on the Surface of Korean Stone Cultural Heritages". Microscopy and Microanalysis 19, S5 (agosto de 2013): 167–71. http://dx.doi.org/10.1017/s1431927613012580.

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AbstractWhite and black deposits have been frequently observed on the surface of Korean stone cultural heritages, and they are considered as damage factors in both conservation and esthetic points of view. In order to set up the appropriate conservation remedy, it is important to know their origins, characteristics, and compositions. In this study, optical and scanning electron microscopes (SEMs) equipped with an energy-dispersive spectrometer (EDS) and X-ray diffractometer were employed to determine the white and black deposits. It was found that both deposits consisted mainly of calcium carbonate (calcite) and calcium sulfate (gypsum). The calcite and gypsum were characterized by bladed, rhombohedral, tabular, and amorphous morphologies under a SEM. The black deposit was not only composed of calcite or gypsum, but also accompanied amorphous and irregular matrix. SEM-EDS analysis revealed an abundance of silicon, aluminum, iron, phosphorus, and carbon on the matrix, which were major elements of soil, atmospheric deposits, and organisms. The white deposit, on the other hand, barely contained those coloring substances. These salts and deposited substances were caused by chemical reaction and physical adhesion between rock-forming minerals, lime mortar, sulfur in polluted air environment, soil dust, and microorganisms.

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Tripathi, B. D., Anamika Tripathi y Kiran Misra. "Atmospheric dustfall deposits in Varanasi City". Atmospheric Environment. Part B. Urban Atmosphere 25, n.º 1 (enero de 1991): 109–12. http://dx.doi.org/10.1016/0957-1272(91)90044-f.

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Dong, Ke, Cheolwoon Woo y Naomichi Yamamoto. "Plant assemblages in atmospheric deposition". Atmospheric Chemistry and Physics 19, n.º 18 (25 de septiembre de 2019): 11969–83. http://dx.doi.org/10.5194/acp-19-11969-2019.

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Abstract. Plants disperse spores, pollen, and fragments into the atmosphere. The emitted plant particles return to the pedosphere by sedimentation (dry deposition) and/or by precipitation (wet deposition) and constitute part of the global cycle of substances. However, little is known regarding the taxonomic diversities and flux densities of plant particles deposited from the atmosphere. Here, plant assemblages were examined in atmospheric deposits collected in Seoul in South Korea. A custom-made automatic sampler was used to collect dry and wet deposition samples for which plant assemblages and quantities were determined using high-throughput sequencing and quantitative polymerase chain reaction (PCR) with universal plant-specific primers targeting the internal transcribed spacer 2 (ITS2) region. Dry deposition was dominant for atmospheric deposition of plant particles (87 %). The remaining 13 % was deposited by precipitation, i.e., wet deposition, via rainout (in-cloud scavenging) and/or washout (below-cloud scavenging). Plant assemblage structures did not differ significantly between dry and wet deposition, indicating a possibility that washout, which is possibly taxon-independent, predominated rainout, which is possibly taxon-dependent, for wet deposition of atmospheric plant particles. A small number of plant genera were detected only in wet deposition, indicating that they might be specifically involved in precipitation through acting as nucleation sites in the atmosphere. Future interannual monitoring will control for the seasonality of atmospheric plant assemblages observed at our sampling site. Future global monitoring is also proposed to investigate geographical differences and investigate whether endemic species are involved in plant-mediated bioprecipitation in regional ecological systems.

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Mohamed, Benahmed, Dellal Abdelkader y Hellal Benchaben. "Mobilite Du Plomb Et Du Zinc Issus De Retombees Atmospheriques Dans Le Sol : Cas De La Zone Industrielle De Tiaret, Algerie". European Scientific Journal, ESJ 12, n.º 18 (29 de junio de 2016): 131. http://dx.doi.org/10.19044/esj.2016.v12n18p131.

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Study of heavy metals mobility in soil is a necessary step for making an accurate appraisal and quantitative evaluation of the extent of contamination, indeed, wet and dry atmospheric deposits, plays an important role in the cycle of semi-volatile contaminants (Vinogradova, 2000). Metallurgical industries release heavy metals into the atmosphere, these last, clump together to form fines particles suspended in the air, these metals can be transported by wind via aerosol or aqueous pathway and deposited in the soil. The main aim of this work was to study the mobility and fate of lead and zinc from atmospheric deposits in a contaminated soil from the foundry (ALFET) in the industrial zone of Tiaret (Western Algeria) and to determine the effect of physicochemical parameters of the soil on their mobility in the topsoil. The physicochemical analysis of soil samples have shown that zinc and lead levels contents in the surface layer soil (0-30cm) vary depending on the pH, total limestone (CaCO3). The obtained results clearly show the major effect of soil texture, the fine fraction (clay and sand).

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Mason, R. H., C. Chou, C. S. McCluskey, E. J. T. Levin, C. L. Schiller, T. C. J. Hill, J. A. Huffman, P. J. DeMott y A. K. Bertram. "The micro-orifice uniform deposit impactor–droplet freezing technique (MOUDI-DFT) for measuring concentrations of ice nucleating particles as a function of size: improvements and initial validation". Atmospheric Measurement Techniques 8, n.º 6 (15 de junio de 2015): 2449–62. http://dx.doi.org/10.5194/amt-8-2449-2015.

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Abstract. The micro-orifice uniform deposit impactor–droplet freezing technique (MOUDI-DFT) combines particle collection by inertial impaction (via the MOUDI) and a microscope-based immersion freezing apparatus (the DFT) to measure atmospheric concentrations of ice nucleating particles (INPs) as a function of size and temperature. In the first part of this study we improved upon this recently introduced technique. Using optical microscopy, we investigated the non-uniformity of MOUDI aerosol deposits at spatial resolutions of 1, 0.25 mm, and for some stages when necessary 0.10 mm. The results from these measurements show that at a spatial resolution of 1 mm and less, the concentration of particles along the MOUDI aerosol deposits can vary by an order of magnitude or more. Since the total area of a MOUDI aerosol deposit ranges from 425 to 605 mm2 and the area analyzed by the DFT is approximately 1.2 mm2, this non-uniformity needs to be taken into account when using the MOUDI-DFT to determine atmospheric concentrations of INPs. Measurements of the non-uniformity of the MOUDI aerosol deposits were used to select positions on the deposits that had relatively small variations in particle concentration and to build substrate holders for the different MOUDI stages. These substrate holders improve reproducibility by holding the substrate in the same location for each measurement and ensure that DFT analysis is only performed on substrate regions with relatively small variations in particle concentration. In addition, the deposit non-uniformity was used to determine correction factors that take the non-uniformity into account when determining atmospheric concentrations of INPs. In the second part of this study, the MOUDI-DFT utilizing the new substrate holders was compared to the continuous flow diffusion chamber (CFDC) technique of Colorado State University. The intercomparison was done using INP concentrations found by the two instruments during ambient measurements of continental aerosols. Results from two sampling periods were compared, and the INP concentrations determined by the two techniques agreed within experimental uncertainty. The agreement observed here is commensurate with the level of agreement found in other studies where CFDC results were compared to INP concentrations measured with other methods.

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Mason, R. H., C. Chou, C. S. McCluskey, E. J. T. Levin, C. L. Schiller, T. C. J. Hill, J. A. Huffman, P. J. DeMott y A. K. Bertram. "The micro-orifice uniform deposit impactor-droplet freezing technique (MOUDI-DFT) for measuring concentrations of ice nucleating particles as a function of size: improvements and initial validation". Atmospheric Measurement Techniques Discussions 8, n.º 2 (27 de febrero de 2015): 2223–61. http://dx.doi.org/10.5194/amtd-8-2223-2015.

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Abstract. The micro-orifice uniform deposit impactor-droplet freezing technique (MOUDI-DFT) combines particle collection by inertial impaction (via the MOUDI) and a microscope-based immersion freezing apparatus (the DFT) to measure atmospheric concentrations of ice nucleating particles (INPs) as a function of size and temperature. In the first part of this study we improved upon this recently introduced technique. Using optical microscopy, we investigated the non-uniformity of MOUDI aerosol deposits at spatial resolutions of 1, 0.25 mm, and for some stages when necessary 0.10 mm. The results from these measurements show that at a spatial resolution of 1 mm and less, the concentration of particles along the MOUDI aerosol deposit can vary by an order of magnitude or more. Since the total area of a MOUDI aerosol deposit ranges from 425 to 605 mm2 and the area analyzed by the DFT is approximately 1.2 mm2, this non-uniformity needs to be taken into account when using the MOUDI-DFT to determine atmospheric concentrations of INPs. Measurements of the non-uniformity of the MOUDI aerosol deposits were used to select positions on the deposits that had relatively small variations in particle concentration and to build substrate holders for the different MOUDI stages. These substrate holders improve reproducibility by holding the substrate in the same location for each measurement and ensure that DFT analysis is only performed on substrate regions with relatively small variations in particle concentration. In addition, the deposit non-uniformity was used to determine correction factors that take the non-uniformity into account when determining atmospheric concentrations of INPs. In the second part of this study, the MOUDI-DFT utilizing the new substrate holders was compared to the continuous flow diffusion chamber (CFDC) technique of Colorado State University. The intercomparison was done using INP concentrations found by the two instruments during ambient measurements of continental aerosols. Results from two sampling periods were compared and the INP concentrations determined by the two techniques agreed within experimental uncertainty. The agreement observed here is commensurate with the level of agreement found in other studies where CFDC results were compared to INP concentrations measured with other methods.

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Barnouin-Jha, Olivier S. y Peter H. Schultz. "Lobateness of impact ejecta deposits from atmospheric interactions". Journal of Geophysical Research: Planets 103, E11 (1 de octubre de 1998): 25739–56. http://dx.doi.org/10.1029/98je02025.

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Bekker, A., M. E. Barley, M. L. Fiorentini, O. J. Rouxel, D. Rumble y S. W. Beresford. "Atmospheric Sulfur in Archean Komatiite-Hosted Nickel Deposits". Science 326, n.º 5956 (19 de noviembre de 2009): 1086–89. http://dx.doi.org/10.1126/science.1177742.

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Lamare, M. L., J. Lee-Taylor y M. D. King. "The impact of atmospheric mineral aerosol deposition on the albedo of snow and sea ice: are snow and sea ice optical properties more important than mineral aerosol optical properties?" Atmospheric Chemistry and Physics Discussions 15, n.º 16 (27 de agosto de 2015): 23131–72. http://dx.doi.org/10.5194/acpd-15-23131-2015.

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Abstract. Knowledge of the albedo of polar regions is crucial for understanding a range of climatic processes that have an impact on a global scale. Light absorbing impurities in atmospheric aerosols deposited on snow and sea ice by aeolian transport absorb solar radiation, reducing albedo. Here, the effects of five mineral aerosol deposits reducing the albedo of polar snow and sea ice are considered. Calculations employing a coupled atmospheric and snow/sea ice radiative-transfer model (TUV-snow) show that the effects of mineral aerosol deposits is strongly dependent on the snow or sea ice type rather than the differences between the aerosol optical characteristics. The change in albedo between five different mineral aerosol deposits with refractive indices varying by a factor of 2 reaches a maximum of 0.0788, whereas the difference between cold polar snow and melting sea ice is 0.8893 for the same mineral loading. Surprisingly, the thickness of a surface layer of snow or sea ice loaded with the same mass-ratio of mineral dust has little effect on albedo. On the contrary, multiple layers of mineral aerosols deposited during episodic events evenly distributed play a similar role in the surface albedo of snow as a loading distributed throughout, even when the layers are further apart. The impact of mineral aerosol deposits is much larger on melting sea ice than on other types of snow and sea ice. Therefore, the higher input of shortwave radiation during the summer melt cycle associated with melting sea ice accelerates the melt process.

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Tesis sobre el tema "Atmospheric deposits"

Westbrook, Owen William. "Crater ice deposits near the south pole of Mars". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53113.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2009.
Includes bibliographical references (p. 55-60).
Layered deposits atop both Martian poles are thought to preserve a record of past climatic conditions in up to three km of water ice and dust. Just beyond the extent of these south polar layered deposits (SPLD), dozens of impact craters contain large mounds of fill material with distinct similarities to the main layered deposits. Previously identified as outliers of the main SPLD, these deposits could offer clues to the climatic history of the Martian south polar region. We extend previous studies of these features by cataloging all crater deposits found near the south pole and quantifying the physical parameters of both the deposits and their host craters. Using MOLA topography data, MOC and THEMIS imagery, and SHARAD radar sounding data, we characterize the distribution, morphology, and structure of the deposits. In addition, we examine the effect of the crater microenvironment on the formation and persistence of these deposits, exploring the relative importance of solar and eolian processes in shaping their present-day distribution and appearance. We consider the possibility that crater sand dunes may have promoted ice accumulation over time and weigh various explanations for the origins and larger climatic significance of these features.
by Own William Westbrook.
S.M.

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Tong, Lege. "Material selection for a dry atmospheric mercury deposits sampler, an integrated chemical and statistical approach". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ35859.pdf.

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Lin, Zhi-Qing. "Trace metal contamination in forests of southern Quebec and pathway studies of airborne metal deposits". Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40177.

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Trace metal contamination of the air-soil-tree system was examined in southern Quebec, where acid deposition and tree dieback have been recorded in high elevation forests. Mn pollution was emphasized due to its large emission from gasoline combustion in Canada. Airborne Cu, Mn, V, and Zn showed higher concentrations than those reported for other remote locations. Significant fluctuation in Mn concentrations during the winter-spring season was explored by air mass back trajectory analysis. The study suggested that high Mn concentrations resulted from the atmospheric long-range transport from Canadian industrialized and metropolitan regions. Metal concentrations in podzolic topsoils were generally higher than their world-wide average values. Concentrations of trace metals in balsam fir (Abies balsamea (L.) Mill) needles were below their suggested potential phytotoxic levels, except for Mn, which also increased with elevation. The scanning of needles with micro-PIXE showed no significant correlation between metal accumulation and epistomatal distribution on foliar surfaces.
Pathways of trace metals deposited in the soil-tree system were elucidated through application of $ sp{54}$Mn and $ sp{65}$Zn on shoot, bark, and soil surfaces in growth-chamber experiments with balsam fir seedlings. Uptake and accumulation by seedlings 70 days after application on the shoot surface was about 25-30% of the remaining activities for $ sp{54}$Mn and $ sp{65}$Zn. Less than 1% of absorbed isotopes was translocated from the bark surface to other plant organs, whereas more than 50% of the radioisotopes absorbed at the shoot moved to the rest of the seedling. Acidic wetness facilitated the metal absorption through tree surfaces. Downward movement of the radioisotopes in podzolic soils was documented, and accumulation in seedlings by root uptake was 5% of the remaining activity for $ sp{54}$Mn and 3% for $ sp{65}$Zn 70 days after application. No appreciable elemental migration from internal tissues to epicuticular wax layers was found, and the leaching ratio was below 0.5 and 1.0% for $ sp{54}$Mn and $ sp{65}$Zn, respectively. This study helps to understand the links between atmospheric deposition and the elevated levels of Mn in trees, and potential effects of acid deposition on the bioaccumulation of toxic metal pollutants in high elevation forests in southern Quebec.

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Craddock, Paul R. "Geochemical tracers of processes affecting the formation of seafloor hydrothermal fluids and deposits in the Manus back-arc basin". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/55328.

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Thesis (Ph. D.)--Joint Program in Chemical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2009.
Includes bibliographical references.
Systematic differences in trace element compositions (rare earth element (REE), heavy metal, metalloid concentrations) of seafloor vent fluids and related deposits from hydrothermal systems in the Manus back-arc basin (Eastern Manus Basin, EMB and Manus Spreading Center, MSC) are used to investigate processes that affect their formation. Processes responsible for observed differences in fluids and deposits from distinct geologic settings include (a) fluid-rock interaction (with temperature, pressure and crustal composition as variables), (b) magmatic acid volatile input and, (c) local seawater entrainment and mixing with hydrothermal fluids, coupled with sulfide precipitation and metal remobilization. REE distributions in vent fluids in the Manus Basin exhibit a wide range of chondrite-normalized patterns that contrast with the relatively uniform distributions observed in mid-ocean ridge vent fluids. This heterogeneity is attributed to marked differences in fluid pH and fluoride and sulfate concentrations that significantly affect REE solubility. The data indicate that REEs can be used as indicators of the styles of magmatic acid volatile input in back-arc hydrothermal systems. Anhydrite in deposits record the same range of REE patterns, suggesting that REE distributions preserved in anhydrite can be used as indicators of past magmatic acid volatile input. Vent fluid heavy metal and metalloid concentrations also exhibit considerable differences. High metal concentrations in EMB versus MSC vent fluids reflect low pH, largely from input of magmatic acid volatiles (indicated by fluoride concentrations greater than seawater). In EMB, metal concentrations are locally affected by dissolution of previously deposited sulfide owing to low pH conditions affected by magmatic acid volatile input or seawater entrainment and mixing with hydrothermal fluid that leads to sulfide precipitation and secondary acidity generation.
(cont.) Massive sulfide deposits in the Manus Basin exhibit a wide range of mineral compositions and heavy metal enrichments. The formation of Zn-rich (sphalerite/wurtzite) deposits in the MSC and of Cu-Fe and Cu-As-rich (chalcopyrite, tennantite) deposits in the EMB reflects differences in the conditions of sulfide precipitation (temperature, pH) and in metal concentrations. The data suggest that heavy metal and metalloid distributions in massive sulfide deposits can be used as indicators of the conditions of vent deposit formation.
by Paul R. Craddock.
Ph.D.

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Delaine, Maxence. "La composition des thèques d'amibes xénosomiques : utilisation potentielle comme bio-indicateur des dépôts de particules d’origine atmosphérique". Thesis, Besançon, 2016. http://www.theses.fr/2016BESA2017/document.

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Les amibes à thèque, également appelés thécamoebiens, sont des micro-organismes unicellulaires, qui construisent une enveloppe rigide, appelée thèque (Adl et al., 2012). Ces thèques ont des tailles, formes et natures très variées (Ogden & Hedley, 1980). Les récentes études sur la composition des thèques ont conduit à émettre l’hypothèse que les amibes xénosomiques (constituées de particules exogènes), peuvent constituer des bio-indicateurs pertinents de la diversité particulaire de l’environnement minéral, organique et biologique dans lequel elles évoluent.L’objectif principal des recherches menées au cours de cette thèse vise donc à caractériser la composition des thèques d’amibes xénosomiques et à en évaluer leur utilisation potentielle en tant que bio-indicateurs des dépôts de particules d'origine atmosphérique. Pour cela, des thèques d’amibes ont été analysées in situ en conditions naturelles et après dépôts artificiels de particules minérales allochtones.Ces travaux permettent de dégager plusieurs conclusions majeures :(1) La taille des particules minérales intégrées dans la thèque xénosomique de Bullinularia indica est similaire à celle des particules minérales transportées dans l'atmosphère; (2) les particules minérales intégrées dans les thèques sont des silicates stables dans les conditions physico-chimiques régnant dans les tourbières, les bryophytes et les sols étudiés; (3) certains minéraux comme la phlogopite, même lorsqu’ils sont présents en de fortes concentrations, ne sont jamais intégrés par les amibes; (4) la combinaison des observations portant sur la taille, la forme et la nature des particules utilisées par des amibes xénosomiques permet de poser les bases de l'utilisation des amibes à thèques pour la bio-indication de la diversité particulaire atmosphérique récente ou ancienne
Theca-like amoebae, also called thecaamoebius, are unicellular microorganisms, which construct a rigid envelope called theca (Adl et al., 2012). These themes have very varied sizes, shapes and natures (Ogden & Hedley, 1980). Recent studies on the composition of the themes have led to the hypothesis that xenosomal amoebae (constituted by exogenous particles) can constitute relevant bio-indicators of the particulate diversity of the mineral, organic and biological environment in which they evolve . The main objective of the research carried out during this thesis is therefore to characterize the composition of the xenosomal amoebae and to evaluate their potential use as bioindicators of deposits of atmospheric particles. For this purpose, amoeba theae were analyzed in situ under natural conditions and after artificial deposits of allochtonous mineral particles. Several major conclusions can be drawn from this work: (1) The size of the mineral particles integrated in the xenosomal theca of Bullinularia indica Is similar to that of mineral particles transported into the atmosphere; (2) the mineral particles integrated into the thecs are stable silicates under the physico-chemical conditions prevailing in the peatlands, bryophytes and soils studied; (3) some minerals such as phlogopite, even when present in high concentrations, are never integrated by amoebae; (4) the combination of observations on the size, shape and nature of the particles used by xenosomic amoebae forms the basis for the use of tea amoeba for bioindication of recent or former atmospheric particulate diversity

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Danna, James G. "Experimental study of clast orientation in gravels deposited by unidirectional flow". Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/57919.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1985.
Microfiche copy available in Archives and Science.
Bibliography: leaves 83-84.
by James G. Danna.
M.S.

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Dunlop, Luke Arthur. "Investigation and comparison of oxide thin films deposited via two low temperature atmospheric pressure routes". Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609263.

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Durrieu, Gael. "Apports fluviaux et atmosphériques d'éléments traces métalliques et métalloïdes en zone côtière méditerranéenne : cas de la rade de Toulon". Electronic Thesis or Diss., Toulon, 2022. http://www.theses.fr/2022TOUL0015.

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Les zones côtières représentent un enjeu majeur en termes d’activités économiques et de préservation d’un bon état chimique et écologique du milieu naturel. Si à l’échelle globale (mer ou océan) les flux de contaminants notamment les éléments traces métalliques et métalloïdes (ETMM) sont relativement bien étudiés et décrits, ce n’est pas le cas des zones plus enclavées à une échelle plus locale. La rade de Toulon qui possède une morphologie semi-fermée est entourée d’une métropole importante (450 000 habitants) avec une forte activité anthropique (premier port militaire en France, ports civils, transport de passagers, aquaculture, …). Ces activités présentes et passées comme la deuxième guerre mondiale, ont conduit à une forte contamination sédimentaire ainsi qu’un fort gradient de concentrations en ETMM entre le Sud de la grande rade, connecté à la mer Méditerranée, et les parties les plus enclavées de la petite rade. Dans ce contexte de zone côtière contaminée, l’objectif de ce travail est d’évaluer la contribution des apports fluviaux et atmosphériques en ETMM à la rade de Toulon. Le mode d’échantillonnage proposé associant des capteurs de terrain, des pièges à particules et des prélèvements ponctuels différenciés entre l’étiage et la crue ont permis d’obtenir une chronique d’apports en ETMM prenant en compte la variabilité météorologique. Les résultats montrent que les apports en ETMM par les rivières (Las et Eygoutier) sont prépondérants durant les crues et dans la fraction particulaire et, sont plus particulièrement préoccupant pour le cuivre et le zinc qui dépassent les seuils réglementaires. Dans le Las, l’apport prépondérant reste cependant le cuivre dissous durant les crues. Dans l’Eygoutier, les valeurs obtenues sont inférieures aux mesures précédemment réalisées en 2004. Les apports en étiage sont largement minoritaires et des teneurs élevées en cadmium et mercure dans les particules ont été mesurées sans pouvoir identifier leur source. Les apports atmosphériques en ETMM sont dominés par la fraction particulaire avec des teneurs dépassant les seuils réglementaires d’un facteur 2 à 4 en cuivre, plomb et zinc. A l’échelle de la rade, les apports fluviaux restent supérieurs aux apports atmosphériques pour tous les ETMM. En faisant un bilan sur l’ensemble de la rade et en prenant en compte les autres sources existantes (ports, ruissellement, stations d’épuration, diffusion sédimentaire), la contribution des apports fluviaux et atmosphériques est estimée à 4 % pour le mercure, autour de 30 % pour le cuivre et le cadmium et près de 70 % pour le plomb et le chrome. Le bilan des flux d’ETMM dans la rade conduit à décrire la rade comme une source de contamination pour la mer Méditerranée. Ceci est confirmé par l’export net calculé pour le plomb, le mercure ou le cadmium tandis que pour le cuivre et le nickel des sources manquantes restent à être déterminées pour confirmer l’hypothèse. Pour le zinc et l’arsenic, la trop grande variabilité empêche de conclure car, ces estimations nécessitent d’être affinées
Coastal areas represent a major issue in terms of economic activities and preservation of a good chemical and ecological status of the natural environment. If on a global scale (sea or ocean) the flow of contaminants, especially trace metals and metalloids (TMM) are relatively well studied and described, this is not the case for more enclosed areas on a more local scale. The Toulon Bay, which has a semi-closed morphology, is surrounded by a large urban area (450 000 inhabitants) with a strong anthropic activity (first military port in France, civil ports, passenger transport, aquaculture, ...). These present and past activities, such as the Second World War, have led to a strong sedimentary contamination as well as a strong gradient of concentrations in TMM between the South of the large bay, connected to the Mediterranean Sea, and the most enclosed parts of the small bay. In this context of contaminated coastal zone, the objective of this work is to evaluate the contribution of the fluvial and atmospheric contributions in TMM to the Toulon Bay. The proposed sampling method associating field sensors, particle traps and punctual sampling differentiated between base flow and flood allowed to obtain a chronicle of TMM inputs considering the meteorological variability. The results show that the inputs of TMM by the rivers (Las and Eygoutier) are preponderant during floods and in the particulate fraction and are more particularly worrying for copper and zinc which exceed the regulatory thresholds. In the Las, the preponderant contribution remains however the dissolved copper during the flood. In the Eygoutier, the values obtained are lower than the measurements previously carried out in 2004. Base flow inputs are largely in the minority and high levels of cadmium and mercury in the particles were measured without being able to identify their source. Atmospheric inputs of TMM are dominated by the particulate fraction with levels exceeding the regulatory thresholds by a factor of 2 to 4 for copper, lead and zinc. At the bay scale, river inputs remain higher than atmospheric inputs for all the TMM. By making a balance on the whole of the bay and by considering the other existing sources (ports, runoff, wastewater treatment plant, sedimentary diffusion), the contribution of river and atmospheric inputs is estimated at 4% for mercury, around 30% for copper and cadmium and nearly 70% for lead and chromium. The balance of TMM inputs in the bay leads to describe the bay as a source of contamination for the Mediterranean Sea. This is confirmed by the net export calculated for lead, mercury, and cadmium, while for copper and nickel missing sources remain to be determined to confirm the hypothesis. For zinc and arsenic, too much variability prevents conclusions being drawn, and these estimates need to be refined

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Fahrni, Jason K. "Assessment of the Severity, Sources, and Meteorological Transport of Ambient and Wet Deposited Mercury in the Ohio River Valley Airshed". Ohio University / OhioLINK, 2005. http://www.ohiolink.edu/etd/view.cgi?ohiou1125427320.

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Elwin, Gareth Steven. "Atmospheric pressure chemical vapour deposition of the nitrides and oxynitrides of vanadium, titanium and chromium". Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322369.

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Libros sobre el tema "Atmospheric deposits"

G, Rault Didier F. y Langley Research Center, eds. Direct simulation Monte Carlo prediction of on-orbit contaminant deposit levels for HALOE. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1994.

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Court, D. G. The deposition and characterisation of atmospheric pressure chemical vapour deposited silicate glass films: A dissertation in partial fulfilment of the requirement for the degree of Master of Science of the Council for National Academic Awards. London: Middlesex Polytechnic, 1988.

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Canada. External Affairs and International Trade Canada. Environment : agreement establishing the Inter-American Institute for Global Change Research Montevideo, May 13, 1992 signed by Canada March 25, 1993, Canadian Notification deposited June 15, 1993 in force for Canada March 12, 1994 =: Environnement : accord relatif à la création d'un institut interaméricain de recherches sur les changements à l'échelle du globe, Montevideao, le 13 mai 1992 signé par le Canada le 25 mars 1993 notification du Canada déposée le 15 juin 1993 en vigueur pour le Canada le 12 mars 1994. Ottawa, Ont: Queen's Printer for Canada = Imprimeur de la Reine pour le Canada, 1995.

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Canfield, Donald Eugene. The Early History of Atmospheric Oxygen: Geological Evidence. Princeton University Press, 2017. http://dx.doi.org/10.23943/princeton/9780691145020.003.0007.

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This chapter explores geological and chemical evidence for the history of atmospheric oxygen on early Earth, with a focus on the Archean Eon. It starts by investigating some of the evidence in the gold mines of South Africa. Some of these mines, located in the Witwatersrand Basin near Johannesburg, have been dug to depths of over 3.9 km (2.4 miles). A closer look at the rocks shows that they represent an ancient river deposit dated to some 2.8 to 3.1 billion years ago. The gold in these deposits was transported by strong river currents and was occasionally trapped among the cobbles and sands forming the riverbed. The presence of oxygen-sensitive minerals in ancient river deposits is pretty compelling evidence for low oxygen concentrations in the early Earth atmosphere.

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Barendregt, R. W., J. V. Matthews, V. Behan-Pelletier, J. Brigham-Grette, J. G. Fyles, L. E. Ovenden, D. H. McNeil et al., eds. Biostratigraphy, Age, and Paleoenvironment of the Pliocene Beaufort Formation on Meighen Island, Canadian Arctic Archipelago. Geological Society of America, 2021. http://dx.doi.org/10.1130/spe551.

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The Beaufort Formation records extraordinary details of Arctic environments and amplified temperatures at approximately modern levels of atmospheric CO2. It was deposited during the Neogene on the western side of what is now the Canadian Arctic Archipelago. Meighen Island is a key locality for studying this formation because marine sediments there are interbedded with terrestrial fossiliferous sands. The biostratigraphic succession, fossils from the marine beds, and paleomagnetic data from the Bjaere Bay region of the island suggest two potential ages for the studied exposures: either continuous deposition at ca. 3.0 Ma, or a sequence of deposits at ca. 4.5 Ma and 3.4 Ma. The sediments appear to encompass at least two eustatic highstands of sea level and a particularly warm climate interval of the Pliocene Arctic.

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Canfield, Donald Eugene. Phanerozoic Oxygen. Princeton University Press, 2017. http://dx.doi.org/10.23943/princeton/9780691145020.003.0011.

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This chapter discusses the modeling of the history of atmospheric oxygen. The most recently deposited sediments will also be the most prone to weathering through processes like sea-level change or uplift of the land. Thus, through rapid recycling, high rates of oxygen production through the burial of organic-rich sediments will quickly lead to high rates of oxygen consumption through the exposure of these organic-rich sediments to weathering. From a modeling perspective, rapid recycling helps to dampen oxygen changes. This is important because the fluxes of oxygen through the atmosphere during organic carbon and pyrite burial, and by weathering, are huge compared to the relatively small amounts of oxygen in the atmosphere. Thus, all of the oxygen in the present atmosphere is cycled through geologic processes of oxygen liberation (organic carbon and pyrite burial) and consumption (weathering) on a time scale of about 2 to 3 million years.

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Kesler, Stephen E. y Hiroshi Ohmoto. Evolution of Early Earth's Atmosphere, Hydrosphere, and Biosphere - Constraints from Ore Deposits. Geological Society of America, 2006. http://dx.doi.org/10.1130/mem198.

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(Editor), Stephen E. Kesler y Hiroshi Ohmoto (Editor), eds. Evolution of Early Earth's Atmosphere, Hydrosphere, And Biosphere: Constraints from Ore Deposits (Memoir (Geological Society of America)). Geological Society of America, 2006.

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Memoir 198: Evolution of Early Earth's Atmosphere, Hydrosphere, and Biosphere - Constraints from Ore Deposits. Geological Society of America, 2006. http://dx.doi.org/10.1130/978-0-8137-1198-0.

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Vaughan, David. 4. Earth’s surface and the cycling of minerals. Oxford University Press, 2014. http://dx.doi.org/10.1093/actrade/9780199682843.003.0004.

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‘Earth’s surface and the cycling of minerals’ considers the rock cycle, which has two parts. The first is driven by the heat coming from the Earth’s interior and involves interactions between the mantle and crust. The second is driven primarily by heat from the Sun and involves interactions between exposed crust and the waters of the hydrosphere or gases of the atmosphere. Minerals in these exposed rocks may be dissolved during weathering, or be transported in the flowing water of streams and rivers, by glaciers, or as fine mineral dusts in the atmosphere, eventually being deposited elsewhere as sediments. The rock cycle also impacts on pollution and global warming.

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Capítulos de libros sobre el tema "Atmospheric deposits"

Birks, N., G. H. Meier y F. S. Pettit. "Degradation of coatings by high temperature atmospheric corrosion and molten salt deposits". En Metallurgical and Ceramic Protective Coatings, 290–305. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-1501-5_11.

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Sirocko, Frank y Michael Sarnthein. "Wind-Borne Deposits in the Northwestern Indian Ocean: Record of Holocene Sediments Versus Modern Satellite Data". En Paleoclimatology and Paleometeorology: Modern and Past Patterns of Global Atmospheric Transport, 401–33. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-0995-3_17.

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Rokosz, M. J., B. E. Artz y R. K. Belitz. "An XRF Method for the Analysis of Atmospheric Aerosol and Vehicular Particulate Deposits on Filters". En Advances in X-Ray Analysis, 177–84. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2471-3_26.

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Conrad, Klaus. "Optimal Intertemporal Pricing of Resource Stocks: The Case of Fossil Fuel Extraction and Atmospheric CO2 Deposits". En ZEW Economic Studies, 291–314. Heidelberg: Physica-Verlag HD, 2003. http://dx.doi.org/10.1007/978-3-642-57415-3_13.

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Kawamura, Hidehisa, Nobuaki Matsuoka, Shinji Tawaki y Noriyuki Momoshima. "Sulfur Isotope Variations in Atmospheric Sulfur Oxides, Particulate Matter and Deposits Collected at Kyushu Island, Japan". En Acid rain 2000, 1775–80. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-007-0810-5_143.

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Cernusak, Lucas A. y Nerea Ubierna. "Carbon Isotope Effects in Relation to CO2 Assimilation by Tree Canopies". En Stable Isotopes in Tree Rings, 291–310. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92698-4_9.

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AbstractThe carbon atoms deposited in tree rings originate from the CO2 in the atmosphere to which the tree’s canopy is exposed. Thus, the first control on the stable carbon-isotope composition of tree rings is by δ13C of atmospheric CO2. There has been an inter-annual trend of decreasing δ13C of atmospheric CO2 over the past two centuries as a result of combustion of fossil fuels and land-use change. Atmospheric CO2 is, for the most part, well mixed, but the sub-canopy air space can become depleted in 13C due to inputs from soil and plant respiration when turbulent exchange with the troposphere is hindered, for example by a high leaf area index at night. This is less likely to occur during daytime when turbulence is higher and photosynthesis takes place. Discrimination against 13C (∆13C) occurs upon assimilation of atmospheric CO2 by C3 photosynthesis. Trees using the C3 photosynthetic pathway comprise the overwhelming majority of all trees. The primary control on the extent of discrimination during C3 photosynthesis is the drawdown in CO2 concentration from the air outside the leaf to the site of carboxylation in the chloroplast. Part of this drawdown is captured by ci/ca, that is, the ratio of intercellular to ambient CO2 concentrations. The ci/ca represents the balance between the CO2 supply by stomata and its demand by photosynthesis. It can be related to water-use efficiency, the amount of CO2 taken up by photosynthesis for a given amount of water loss to the atmosphere, assuming a given evaporative demand. To predict time-averaged ci/ca from wood ∆13C, a simplified, linear model can be employed. In this linear model, the slope is determined by $$\overline{b }$$ b ¯ , the effective enzymatic discrimination. The value of $$\overline{b }$$ b ¯ can be estimated by comparing wood ∆13C to representative measurements of ci/ca. The $$\overline{b }$$ b ¯ was originally estimated from observations of leaf tissue to have a value of 27‰. We compiled data for woody stem tissue here, and our analysis suggests that a lower $$\overline{b }$$ b ¯ should be used in the simplified model for wood ($$\overline{b }$$ b ¯ = 25.5‰) than for leaves ($$\overline{b }$$ b ¯ = 27‰). This is also consistent with widespread observations that woody tissues are enriched in 13C compared to leaves.

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Frimmel, Hartwig E. "The world’s largest gold province: Implications on Archaean atmospheric evolution". En Mineral Deposit Research: Meeting the Global Challenge, 949–52. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/3-540-27946-6_242.

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Burkhardt, Jürgen, Kerstin Koch y Hartmut Kaiser. "Deliquescence of Deposited Atmospheric Particles on Leaf Surfaces". En Air-Surface Exchange of Gases and Particles (2000), 313–21. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-9026-1_31.

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Schmitt, J. M. "Weathering, Rainwater and Atmosphere Chemistry: Example and Modelling of Granite Weathering in Present Conditions in a CO2-Rich, and in an Anoxic Palaeoatmosphere". En Palaeoweathering, Palaeosurfaces and Related Continental Deposits, 19–41. Oxford, UK: Blackwell Publishing Ltd., 2009. http://dx.doi.org/10.1002/9781444304190.ch1.

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Spiegel, M. y H. J. Grabke. "Corrosion of 2.25CR-1MO Steel Under Fly Ash Deposits in Simulated Waste Incineration Atmospheres". En The Impact of Ash Deposition on Coal Fired Plants, 779–84. Boca Raton: Routledge, 2022. http://dx.doi.org/10.1201/9780203736616-70.

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Actas de conferencias sobre el tema "Atmospheric deposits"

Kolotkov, Gennady A. "Remote detection of rare-earth metal deposits by secondary microwave radiation". En 27th International Symposium on Atmospheric and Ocean Optics, Atmospheric Physics, editado por Oleg A. Romanovskii y Gennadii G. Matvienko. SPIE, 2021. http://dx.doi.org/10.1117/12.2603381.

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Dong, Xin-Yuan, Xiao-Tao Luo, Shan-Lin Zhang y Chang-Jiu Li. "A Novel Strategy for Applying Oxide-Free Self-Fluxing Alloy Coatings by Self-Fusing Atmospheric Plasma Spraying". En ITSC2019, editado por F. Azarmi, K. Balani, H. Koivuluoto, Y. Lau, H. Li, K. Shinoda, F. Toma, J. Veilleux y C. Widener. ASM International, 2019. http://dx.doi.org/10.31399/asm.cp.itsc2019p0682.

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Abstract In this study, NiCrBSi powders with a size range of 30-50 μm were deposited on mild steel substrates by self-fusing atmospheric plasma spraying. Particle temperatures exceeded 2400 °C and the deposits were remarkably dense with low oxygen content. Based on the results, a novel strategy is proposed to directly deposit dense, oxide-free coatings by plasma spraying without the need of post-spray fusing processes.

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Zhang, C., H. Liao, W. Y. Li, C. Coddel, C. J. Li, C. X. Li y X. J. Ning. "Characterization of YSZ SOFC Electrolyte Deposited by Atmospheric Plasma Spraying and Low Pressure Plasma Spraying". En ITSC2006, editado por B. R. Marple, M. M. Hyland, Y. C. Lau, R. S. Lima y J. Voyer. ASM International, 2006. http://dx.doi.org/10.31399/asm.cp.itsc2006p0415.

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Abstract Yttria doped zirconia has been widely employed as electrolyte materials for solid oxide fuel cells (SOFCs). Plasma spraying is a cost-effective process to deposit YSZ electrolyte. In this study, the 8 mol % Y2O3 stabilized ZrO2 (YSZ) layer was deposited by low pressure plasma spraying (LPPS) and atmospheric plasma spraying (APS) with fused-crushed and agglomerated powders to examine the effect of spray method and particle size on the electrical conductivity and gas permeability of YSZ coating. The microstructure of YSZ coating was characterized by scanning electron microscopy and X-ray diffraction analysis. The results showed that the gas permeability was significantly influenced by powder structure. The gas permeability of YSZ coating deposited by fused-crushed powder is one order lower in magnitude than that by agglomerated powder. Moreover, the gas permeability of YSZ deposited by LPPS is lower than that of APS YSZ. The electrical conductivity of the deposits through thickness direction was measured by potentiostat/galvanostat based on three-electrode assembly approach. The electrical conductivity of YSZ coating deposited by LPPS with fused-crushed powder of small particle size was 0.043 S × cm-1 at 1000°C, which is about 20% higher than that of APS YSZ with the same powder.

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Saunders-Shultz, Che Pablo y Anna M. Martini. "ATMOSPHERIC MIXING MODELS OF FUGITIVE METHANE EMISSIONS FROM SHALE GAS DEPOSITS". En 54th Annual GSA Northeastern Section Meeting - 2019. Geological Society of America, 2019. http://dx.doi.org/10.1130/abs/2019ne-328106.

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Dean, Anthony J., Jean E. Bradt y John F. Ackerman. "Deposit Formation From No. 2 Distillate at Gas Turbine Conditions". En ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-046.

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Carbon deposit tests using No. 2 distillate fuel were performed in a flowing fuel/flowing atmosphere chamber utilizing a heated vertical test plate which simulates the interactions of fuel spray with combustor surfaces in a gas turbine downstream of the fuel nozzle. This type of interaction can occur in the premixing region of a low-NOx combustor operating on No. 2 fuel and can impact performance and reliability. Deposit formation was studied as a function of surface temperature, surface composition, duration of exposure, atmospheric composition, and fuel type. Surface temperature and oxygen content in the atmosphere appear to have the greatest effect upon deposition: whereas the surface composition and exposure duration have a negligible effect. Conversion of fuel to deposits decreases somewhat as fuel flaw rate increases. A peak conversion to deposits of 0.1 grams per kg of fuel (0.01% conversion) occurred at a surface temperature of 345 C (653 F). The conversion fraction dropped to less than 1% of [he peak conversion below 225 C (437 F) and above 410 C (777 F). A comparison with published data from horizontal plate tests show different rates at specific temperatures which can be attributed to the test geometry, flow rate and residence time.

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Chen, Xu, Shan-Lin Zhang, Cheng-Xin Li y Chang-Jiu Li. "Characterization of Atmospheric Plasma-Sprayed Strontium Doped Lanthanum Chromite Interconnector for Tubular Solid Oxide Fuel Cells". En ITSC2019, editado por F. Azarmi, K. Balani, H. Koivuluoto, Y. Lau, H. Li, K. Shinoda, F. Toma, J. Veilleux y C. Widener. ASM International, 2019. http://dx.doi.org/10.31399/asm.cp.itsc2019p0376.

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Abstract This study investigates the effect of deposition temperature and particle size on lanthanum strontium chromite (LSC) deposits produced by atmospheric plasma spraying. The results show that dense deposits with lamellar interface bonding can be achieved at temperatures above the critical bonding temperature and that particle size has a significant effect on chromium vaporization losses. The loss of chromium may be responsible for the low electrical conductivity of LSC deposits produced from small powders, which suggests that conductivity can be controlled with appropriate process adjustments.

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Normand, B., F. Renaud, C. Coddet y F. Tourenne. "The Effect of Spraying Conditions on the Corrosion Resistance of Titanium Coatings for Surgical Implants". En ITSC 1996, editado por C. C. Berndt. ASM International, 1996. http://dx.doi.org/10.31399/asm.cp.itsc1996p0073.

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Abstract One cause of aseptic loosening of total hip replacement (THR) results from the hard polymetylmethacrylate (PMMA) bone cement debris embedded within some of acetabular cups [1]. To prevent this failure, PMMA can be replaced by a titanium coating with a specific roughness to promote the bone bonding. In this work, inert and atmospheric plasma spraying was used to coat Ti.6A1.4V implants with titanium.] In order to evaluate the effect of the deposition process on the coating corrosion resistance, different electrochemical techniques were implemented in physiological (i. e., Ringer) and in acidic solutions. Results show that the spraying parameters and the coating morphology affect the corrosion behaviour. Thus, if the reactivity is not affected by the pH evolution, the pitting sensitivity depends on the process. It was found that coatings deposited under inert gas are free of oxides and dense, even when the atmosphere contains some hydrogen. In that case a significant improvement of the intrinsic localized corrosion resistance is observed versus deposits obtained using atmospheric plasma spraying.

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Yanhua Wang. "Notice of Retraction: Contamination of magnesium alloy with chloride deposits under marine atmospheric conditions". En 2010 Second IITA International Conference on Geoscience and Remote Sensing (IITA-GRS 2010). IEEE, 2010. http://dx.doi.org/10.1109/iita-grs.2010.5602721.

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Fervel, V., B. Normand, C. Coddet y M. Delaet. "Tribological Properties of Mo/NiCrBSi Thermal Spray Deposits". En ITSC 1998, editado por Christian Coddet. ASM International, 1998. http://dx.doi.org/10.31399/asm.cp.itsc1998p0237.

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Abstract The tribological behavior of Mo/NiCrBSi coatings obtained by atmospheric plasma spray was studied under dry conditions using an Amsler machine. Discussion is made on the effects of the plasma gas mixture and of the preheating of the substrate. The wear process of Mo/NiCrBSi in situation of dry rolling-sliding contact versus cast iron was observed using a profilometer, an optical microscope, and a scanning electron microscope. It was found that the wear mechanism could be divided into two steps : the first one corresponds to an abrasive wear; it results from the difference in hardness between the counter-specimen and the Mo/NiCrBSi coating. The second one corresponds to an adhesive wear resulting from the transfer of cast iron from the counter-specimen to the coating.

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Hao, S., C. J. Li, G. J. Yang y Y. Z. Xing. "Influence of Substrate Surface Temperature on the Microstructure and Properties of Plasma-Sprayed Al2O3 Coatings". En ITSC2010, editado por B. R. Marple, A. Agarwal, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima y G. Montavon. DVS Media GmbH, 2010. http://dx.doi.org/10.31399/asm.cp.itsc2010p0259.

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Abstract Thermally sprayed ceramic coatings have a layered structure with a limited interface bonding. Substrate surface temperature prior to droplets impact during deposition significantly influences the microstructure and properties of the coatings. Through the controlling of substrate surface temperature, the lamellar interface bonding of the deposits could be possibly improved. Al2O3 coatings were deposited by atmospheric plasma spraying at the surface temperatures of 100, 275, 375, 480, 530 and 660°C. The fractured cross-section morphology was characterized by scanning electron microscopy. X-ray diffraction was used to analyse the phase contents. Micro-hardness, Young’s modulus and thermal conductivity of the deposits were measured. It was observed that the interface area with columnar grain growth across splat-splat interfaces was increased with increasing deposition temperature. Consequently, micro-hardness, Young’s modulus and thermal conductivity were increased with the increase of deposition temperature. The improvement of properties suggest that the lamellar interface bonding in the deposits was improved as the substrate surface temperature is increased.

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Informes sobre el tema "Atmospheric deposits"

Douglas, Thomas y Joel Blum. Mercury isotopes reveal atmospheric gaseous mercury deposition directly to the Arctic coastal snowpack. Engineer Research and Development Center (U.S.), junio de 2021. http://dx.doi.org/10.21079/11681/41046.

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Springtime atmospheric mercury depletion events (AMDEs) lead to snow with elevated mercury concentrations (>200 ng Hg/L) in the Arctic and Antarctic. During AMDEs gaseous elemental mercury (GEM) is photochemically oxidized by halogens to reactive gaseous mercury which is deposited to the snowpack. This reactive mercury is either photochemically reduced back to GEM and reemitted to the atmosphere or remains in the snowpack until spring snowmelt. GEM is also deposited to the snowpack and tundra vegetation by reactive surface uptake (dry deposition) from the atmosphere. There is little consensus on the proportion of AMDE-sourced Hg versus Hg from dry deposition that is released in spring runoff. We used mercury stable isotope measurements of GEM, snowfall, snowpack, snowmelt, surface water, vegetation, and peat from a northern Alaska coastal watershed to quantify Hg sources. Although high Hg concentrations are deposited to the snowpack during AMDEs, we estimate that ∼76 to 91% is released back to the atmosphere prior to snowmelt. Mercury deposited to the snowpack as GEM comprises the majority of snowmelt Hg and has a Hg stable isotope composition similar to Hg deposited by reactive surface uptake of GEM into the leaves of trees in temperate forests. This GEM-sourced Hg is the dominant Hg we measured in the spring snowpack and in tundra peat permafrost deposits.

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Douglas, Thomas, Matthew Sturm, Joel Blum, Christopher Polashenski, Svetlana Stuefer, Christopher Hiemstra, Alexandra Steffen, Simon Filhol y Romain Prevost. A pulse of mercury and major ions in snowmelt runoff from a small Arctic Alaska watershed. Engineer Research and Development Center (U.S.), julio de 2021. http://dx.doi.org/10.21079/11681/41203.

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Atmospheric mercury (Hg) is deposited to Polar Regions during springtime atmospheric mercury depletion events (AMDEs) that require halogens and snow or ice surfaces. The fate of this Hg during and following snowmelt is largely unknown. We measured Hg, major ions, and stable water isotopes from the snowpack through the entire spring melt runoff period for two years. Our small (2.5 ha) watershed is near Barrow (now Utqiaġvik), Alaska. We measured discharge, made 10 000 snow depths, and collected over 100 samples of snow and meltwater for chemical analysis in 2008 and 2009 from the watershed snowpack and ephemeral stream channel. Our results suggest AMDE Hg complexed with Cl⁻ or Br⁻ may be less likely to be photochemically reduced and re-emitted to the atmosphere prior to snowmelt, and we estimate that roughly 25% of the Hg in snowmelt is attributable to AMDEs. Projected Arctic warming, with more open sea ice leads providing halogen sources that promote AMDEs, may provide enhanced Hg deposition, reduced Hg emission and, ultimately, an increase in snowpack and snowmelt runoff Hg concentrations.

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Langlois, E., S. D. Murthy, I. Bhat, R. Gutmann, E. Brown, R. Dziendziel, M. Freeman y N. Choudhury. Characteristics of indium oxide plasma filters deposited by atmospheric pressure CVD. Office of Scientific and Technical Information (OSTI), julio de 1995. http://dx.doi.org/10.2172/350942.

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Branch, Brittany, Chad McCoy y Andrew Vackel. Impact Response of Control Atmosphere Plasma Spray Deposited Materials. Office of Scientific and Technical Information (OSTI), mayo de 2022. http://dx.doi.org/10.2172/1868139.

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Lin, Hongwei, Yanjun Gao, Kang Sun y Faguang Jin. Association between PM2.5 pollution and outpatient visits for respiratory diseases in China: a systematic review and meta-analysis. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, mayo de 2022. http://dx.doi.org/10.37766/inplasy2022.5.0144.

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Review question / Objective: Previous epidemiological studies on the association between PM2.5 pollution and outpatient visits for respiratory diseases in China were mostly limited to one region， and the different papers have no coherent results. Our objective is to perform a systematic review and meta-analysis of the relevant literature in order to summarize the association between PM2.5 pollution and outpatient visits for respiratory diseases in multiple cities in China. Condition being studied: As an important component of air pollutants, particulate matter 2.5 (PM2.5) can float in the atmosphere for a long time with a small aerodynamic size (≤2.5μm) and large specific surface area which is attached to a variety of toxic and harmful substances . PM2.5 can deposite under the trachea of the respiratory tract, reaching deep into the alveolar area, damaging alveolar macrophages and type Ⅱ alveolar epithelial cells, inducing alveolar inflammation, resulting in decreased immunity of the respiratory tract and interfering with normal physiological functions of the lungs.

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EGR Cooler Fouling Reduction: A New Method for Assessment in Early Engine Development Phase. SAE International, marzo de 2022. http://dx.doi.org/10.4271/022-01-0589.

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High pressure EGR provides NOx emission reduction even at low exhaust temperatures. To maintain a safe EGR system operation over a required lifetime, the EGR cooler fouling must not exceed an allowable level, even if the engine is operated under worst-case conditions. A reliable fouling simulation model represents a valuable tool in the engine development process, which validates operating and calibration strategies regarding fouling tendency, helping to avoid fouling issues in a late development phase close to series production. Long-chained hydrocarbons in the exhaust gas essentially impact the fouling layer formation. Therefore, a simulation model requires reliable input data especially regarding mass flow of long-chained hydrocarbons transported into the cooler. There is a huge number of different hydrocarbon species in the exhaust gas, but their individual concentration typically is very low, close to the detection limit of standard in-situ measurement equipment like GC-MS. Therefore, a new measurement and analysis approach has been developed, where the exhaust gas is guided to a metal foam collector, in which HC`s are deposited. The probe is then analyzed in a suited thermogravimetrical system (TGA) in nitrogen atmosphere, temperature range 25°C to 650°C. Analyzing the TGA curve, HC concentration data for 6 different boiling temperature ranges are obtained, provided to an adapted 1-d fouling simulation model. Using these data along with further input parameters like cooler geometry, gas temperature, pressure, flow, particle size distribution and coolant temperature, the simulation model has proven as a suitable tool to predict the fouling and identify engine settings for fouling reduction.

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